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relevant items from most recent CHAVI update -
(focus on innate immune response to acute HIV infection, and passive antibody therapy taking front seat as a way to see if and what antibodies may be important to elicit...)
- also Haynes most recent conf. poster, from Seattle, Sept 07
--------
Note Haynes colleague David Pisetsky on the most recent PS work above, since apoptotic debris (PS-exposing microparticles) are now seen as the hurdle to deal with, as explained in the protocol of the most recently initiated CHAVI study, CHAVI 012.
More Pisetsky -
Duke's David Pisetsky, & microparticles....
(Pisetsky is the Director of the dept of rheumatology at Duke, a position formerly held by Barton Haynes)
The release of microparticles by apoptotic cells and their effects on macrophages
Apoptosis: Volume 10, Number 4 / August, 2005
J. H. W. Distler3, L. C. Huber1, A. J. Hueber2, C. F. Reich III3, S. Gay1, O. Distler1 and D. S. Pisetsky3
(1) Center of Experimental Rheumatology, Department of Rheumatology, University Hospital Zurich, Zurich, CH-8091, Switzerland
(2) Department of Rheumatology and Internal Medicine, University of Erlangen-Nuremberg, Erlangen, D-91054, Germany
(3) Division of Rheumatology, Durham VA Hospital and Duke University Medical Center, Durham, NC, USA
Microparticles are small membrane vesicles released from the cell membrane by exogenous budding. To elucidate the interactions of microparticles with macrophages, the effect of microparticles released from Jurkat T cells on RAW 264.7 cells was determined. Microparticles were isolated by differential centrifugation, using FACS analysis with annexin V and cell surface markers for identification. Various inducers of apoptosis increased the release of microparticles from Jurkat cells up to 5-fold. The released microparticles were then cultured with RAW 264.7 cells. As shown by confocal microscopy and FACS analysis, RAW 264.7 macrophages cleared microparticles by phagocytosis. In addition, microparticles induced apoptosis in RAW 264.7 cells in a dose-dependent manner with up to a 5-fold increase of annexin V positive cells and 9-fold increase in caspase 3 activity. Cell proliferation as determined by the MTT test was also reduced. Furthermore, microparticles stimulated the release of microparticles from macrophages. These effects were specific for macrophages, since no apoptosis was observed in NIH 3T3 and L929 cells. These findings indicate that microparticles can induce macrophages to undergo apoptosis, in turn resulting in a further increase of microparticles. The release of microparticles from apoptotic cells may therefore represent a novel amplification loop of cell death.
Pisetsky Dec 06
Autoimmunity. 2006 Dec
Microparticles as mediators of cellular cross-talk in inflammatory disease.
Distler JH, Huber LC, Gay S, Distler O, Pisetsky DS.
Microparticles are a heterogeneous population of membrane-coated vesicles which can be released from virtually all cell types during activation or apoptosis. Release occurs from the cell surface in an exogenous budding process involving local rearrangement of the cytoskeleton. Given their origin, these particles can be identified by staining for cell surface markers and annexin V. As shown in in vitro studies, microparticles may represent a novel subcellular element for intercellular communication in inflammation. Thus, microparticles can transfer chemokine receptors and arachidonic acid between cells, activate complement, promote leukocyte rolling and stimulate the release of pro-inflammatory mediators. Under certain conditions, however, microparticles may also exert anti-inflammatory properties by inducing immune cell apoptosis and the production of anti-inflammatory mediators. Microparticles may play an important role in the pathogenesis of rheumatologic diseases as evidenced by their elevation in diseases such as systemic sclerosis (SSc), systemic vasculitis and antiphospholipid antibody syndrome and correlation with clinical events. A role in inflammatory arthritis is suggested by the finding that leukocyte-derived microparticles induce the production of matrix metalloproteinases and cytokines by synovial fibroblasts. Together, these findings point to novel signaling pathways of cellular cross-talk that may operate along the spectrum of soluble cytokines and mediators of direct cell-cell contact.
---------------------
Pisetsky's latest - microparticles, Aug/Sept 2007
Duke's Pisetsky Aug/Sept 2007
Scand J Immunol. 2007 Aug-Sep
The role of microparticles in inflammation and thrombosis.
Ardoin SP, Shanahan JC, Pisetsky DS.
Division of Rheumatology and Immunology, Duke University Medical Center, Medical Research Service, Durham VA Hospital, Durham, NC, USA.
Microparticles (MP) are small membrane-bound vesicles that circulate in the peripheral blood and play active roles in thrombosis, inflammation and vascular reactivity. While MP can be released from nearly every cell type, most investigation has focused on MP of platelet, leucocyte and endothelial cell origin. Cells can release MP during activation or death. Flow cytometry is the usual method to quantify MP; the small size of these structures and lack of standardization in methodology complicate measurement. As MP contain surface and cytoplasmic contents of the parent cells and bear phosphatidylserine, antibodies to specific cell surface markers and annexin V can be used for identification. Through various mechanisms, MP participate in haemostasis and have procoagulant potential in disease. MP contribute to inflammation via their influence on cell-cell interactions and cytokine release, and MP also function in mediating vascular tone. In several disease states characterized by inflammation and vascular dysfunction, MP subpopulations are elevated, correlate with clinical events, and may have important roles in pathogenesis. In the rheumatic conditions such as rheumatoid arthritis and systemic lupus erythematosus, MP are potentially important markers of disease activity and have an increasingly recognized role in immunopathogenesis. It is clear that MP play an important role in atherosclerosis, and study of these structures may provide insight into the link between chronic inflammatory conditions and accelerated atherosclerosis. As biomarkers, MP allow access to usually inaccessible tissues such as the endothelium. Further research will hopefully lead to interventions targeting MP release and function.
-----------------------------------
Duke's Bart Haynes, & microparticles....
(Haynes: CHAVI director, Gates CAVD leader, Duke Human Vaccine Institute Director, former director of Duke rheumatology, replaced by ...)
January 07 CHAVI Administrators meeting-
January 07 CHAVI Administrators meeting-
Bart Haynes Gates CAVD webpage- March 07 -
--------------------------------------
new from the Pasteur Institute -
TGF-beta in intestinal lymphoid organs contributes to the death of armed effector CD8 T cells
and is associated with the absence of virus containment in rhesus macaques infected with the simian immunodeficiency virus
http://www.nature.com/cdd/journal/v14/n10/abs/4402192a.html
SIV-infected macaques exhibit distinct rates of progression to AIDS and despite significant increases in CD8+ T cells, immune cells fail to control and eradicate SIV in vivo. Here, we investigated the interplay between viral reservoir sites, CD8+ T-cell activation/death and outcome. Our data provide strong evidence that mesenteric (Mes) lymph nodes represent major reservoirs not only for SIV-infected macaques progressing more rapidly toward AIDS but also in controllers. We demonstrate that macaques progressing faster display greater expression of TGF-beta and Indoleamine 2,3 dioxygenase in particular in intestinal tissues associated with a phosphorylation of the p53 protein on serine 15 in CD8+ T cells from Mes lymph nodes. These factors may act as a negative regulator of CD8+ T-cell function by inducing a Bax/Bak/Puma-dependent death pathway of effector/memory CD8+ T cells. Greater T-cell death and viral dissemination was associated with a low level of TIA-1+ expressing cells. Finally, we provide evidence that abrogation of TGF-beta in vitro enhances T-cell proliferation and reduces CD8+ T-cell death.Our data identify a mechanism of T-cell exhaustion in intestinal lymphoid organs and define a potentially effective immunological strategy for the modulation of progression to AIDS.
Keywords:AIDS, reservoir, IDO, apoptosis, PD-1, p53
-----------------------------------------
Bavituximab Immune-Modulating MOA:
Bavituximab Immune-Modulating MOA Investigative Collaborators:
j
a bit of detail on the MRK / NIH failed vaccine -
Perplexing Results of Failed HIV Vaccine Grow More Puzzling
http://www.medpagetoday.com/HIVAIDS/HIVAIDS/tb/7305
SEATTLE, Nov. 8 -- HIV vaccine researchers remain puzzled by the results of the ill-starred STEP trial, halted in September because of a lack of efficacy.
New results just released also hint that the vaccine might have slightly increased the risk of HIV infection.
Volunteers who had a high level of pre-existing immunity to the adenovirus vector used in the vaccine seemed to be more vulnerable to HIV infection, the researchers revealed in a special forum here.
But the researchers also said the data are complex and will require more in-depth analysis before it's clear what happened.
"It will take some time before we understand why the vaccine did not work and why there was a trend toward more cases of infection in volunteers who received the vaccine," said Keith Gottesdiener, M.D., of Merck Research Laboratories, which was developing the vaccine.
The vaccine includes three viral genes delivered by an adenovirus-5 vector, and in earlier clinical trials appeared to generate a significant HIV-specific cell-mediated immune response.
It was being tested in two large phase IIb trials, STEP in North and South America, the Caribbean, and Australia and Phambili in South Africa. Both trials stopped vaccinating volunteers after the STEP data safety monitoring committee found the vaccine wasn't efficacious. (See: Hopes Dashed Again for HIV Preventive Vaccine)
But in a special open scientific meeting of the HIV Vaccine Trials Network, researchers revealed more details of the ill-fated trial.
The key finding that led to halting the trial was that among volunteers with low pre-existing immunity to the adenovirus vector who were HIV-negative at the start of the trial, 24 of the 741 who got the vaccine developed an HIV infection, compared with 21 in the 762 who got placebo.
When the researchers restricted the analysis to those who got at least two of three planned vaccinations and who remained HIV-negative for at least the first 12 weeks of the trial, they found 19 HIV infections in the 672 volunteers who got the vaccine and 11 in the 691 who got placebo.
In the whole study population, including cases recorded after the trial was stopped, there were 49 cases of HIV infection among the 914 men in the vaccine group compared with 33 cases among the 922 in the placebo group.
The vaccine also failed to achieve its secondary endpoint -- reducing the HIV viral levels among volunteers who got infected despite the vaccine.
When the trial was stopped, researchers said that the HIV RNA levels approximately eight to 12 weeks after diagnosis of infection were generally similar in the two groups -- but with a trend toward higher levels in those who got the vaccine.
HIV RNA levels in the blood were about 40,000 copies per milliliter among volunteers in the vaccine group who developed HIV infection and approximately 26,000 copies per milliliter in infected volunteers in the placebo group.
When the entire study population was taken into account, including male volunteers with both low and high levels of immunity to Ad5, the geometric means of HIV RNA levels were approximately 29,000 copies/mL for the vaccine group (based on 46 infections) and approximately 38,000 copies/mL in the placebo group (based on 30 infections).
The study wasn’t designed to look at the effect of immunity to adenovirus on HIV acquisition, but a post hoc analysis showed that HIV infection among volunteers with high Ad5 immunity was more pronounced among those that received the vaccine compared to those who received placebo.
Among the 778 male volunteers who had high levels of pre-existing immunity, there were 21 cases of HIV infection in the vaccine group and nine in the placebo group.
The researchers also said that among volunteers who had no or limited pre-existing immunity to adenovirus, there was little difference in the HIV infection rate.
Researchers outside the trial emphasized that there remain large knowledge gaps.
"We know the Merck vaccine didn't work," said Seth Berkley, M.D., president of the New York-based International AIDS Vaccine Initiative. "We don't know why."
"We know that more people who got the Merck [vaccine] candidate than got the placebo wound up becoming HIV infected," he said in a statement. "We don't know if that had anything to do with the candidate or not."
He added that the trend was not statistically significant, so "it could have been chance. And if the vaccine was a factor, we don't know why."
Dr. Berkley said many in the vaccine community were not surprised by the result.
"The failure of the Merck product to prevent HIV infection is not unexpected," he said, because the vaccine -- like nearly all of those in the pipeline -- aimed at producing cell-mediated immunity.
But T cells only attack infected cells, so that "many scientists, including those at IAVI, think T-cell vaccines are unlikely to protect individuals from becoming infected."
Likely to be more effective, Dr. Berkley said, would be vaccines aimed at producing an antibody response and thus preventing HIV particles from entering the body.
--------
Meanwhile, CHAVI/Gates are running passive antibody therapy experiments to see what antibodies might be worth trying to elicit...
I wonder what they've found.
j
interesting to see two 500,000 share trades go off above the ask.
j
oh - jake -
Please provide me with a list, no, not a list,..... kindly provide me with a SINGLE company that is "on their heels", developing antibodies to anionic phospholipids as therapeutics.
You will not find a SINGLE one.
There is nobody "on their heels", - (yet)...
Peregrine is entering phase 2 with an anti-anionic-phopholipid mab.
j
jake,
PPHM has exclusive license to Thorpe's work for as long as PPHM makes the monthly sponsored research payments.
For UTSW to take the tech back, they would have to prove that PPHM has not tried to advance the tech, that PPHM had shelved or abandoned the tech, (and obviously they are advancing the tech). There are no deadlines. There are no grey area 'speed of advancing the tech' issues, nothing. PPHM is spending money researching and advancing bavi, which means that the tech is exclusively Peregrine's for as long as they want it, period.
BTW - UTSW, just a couple months ago, outlicensed a "next gen." anti-PS to guess who... - Peregrine.
(Schroit's "double" Beta-2-glycoprotein-I )
If you are disappointed in the rate of Bavi advance, (I'm not), you should look into the FDA's original inclusion/exclusion criteria for the first (1A) cancer trial, even after Peregrine's abundance of safety/tox data provided... Realize that targeting PS was seriously thought to be taboo, (and still is seen that way by many in the immunological science community who aren't up on the recent discoveries that have differentiated pathogenic from non-pathogenic autoantibodies, - especially those with plasma protein cofactors like bavi...)
j
sunstar,
Actually that graph with the impressive log reductions, including the 1.5 log reduction in the 3 mg patient was from the earlier, single-dose study.
Godofsky's whole AASLD '06 presentation is here -
http://209.63.37.57/courses/2006/PAR/18/Godofsky/player.html
It was amazing in that single dose study that patients' viral load was still lower 12 weeks after that single dose!
(Due to Bavi's immune modulating MOA)
I'm looking forward to Lawitz's '07 presentation showing up online.
j
slipperypete,
in a nut-shell, the answer is yes.
j
slipperypete,
Today is the first mention of proof in humans that Bavituximab alters cytokines, - (less TGF-B, and more TNF-A), and that's a very important thing.
(It's exactly what I was hoping they'd mention.)
Maybe folks will get a little more out of these now that there is proof- in humans- that PS-blocking (with Bavituximab) alters immune response -
------------------------------------
Interaction between Phosphatidylserine and the Phosphatidylserine Receptor Inhibits Immune Responses In Vivo
http://www.jimmunol.org/cgi/content/full/174/3/1393
Peter R. Hoffmann2,*, Jennifer A. Kench*, Andrea Vondracek{dagger}, Ellen Kruk*, David L. Daleke{ddagger}, Michael Jordan{dagger}, Philippa Marrack{dagger}, Peter M. Henson* and Valerie A. Fadok*,{dagger}
The Journal of Immunology, 2005
.
Interaction between Phosphatidylserine and the Phosphatidylserine Receptor Inhibits Immune Responses In Vivo
Introduction
The rapid engulfment of apoptotic cells by professional and nonprofessional phagocytes prevents the release of potentially toxic or immunogenic intracellular contents from the dying cells (1, 2, 3, 4). Much attention has recently focused on the effects of apoptotic cells on phagocytes engulfing them. Interactions between macrophages and apoptotic cells result in the secretion of anti-inflammatory mediators such as TGF-{beta}, IL-10, and PGE2, as well as inhibition of the production of proinflammatory mediators (5, 6, 7, 8, 9, 10, 11). Similar results have been found with nonleukocytic phagocytes including fibroblasts and epithelial cells (Ref.12 ; J. Monks and V. A. Fadok, unpublished observations). In addition, apoptotic cells have been shown in some cases to inhibit dendritic cell maturation and Ag presentation (13, 14, 15).
Apoptotic cells have also been shown to affect inflammation and adaptive immune responses in vivo, although the results are conflicting. For example, apoptotic cells have been shown to be poor adjuvants compared with their necrotic counterparts in the generation of delayed-type hypersensitivity (15). Other evidence suggests that the uptake of apoptotic cells is not an immunologically null event, but is capable of modulating immune responses to self-Ags through induction of T cell-tolerance (16). The tolerizing effects of apoptotic cells have been further demonstrated in studies in which injection of apoptotic cells inhibited rejection of bone marrow allografts (17). By contrast, it has been suggested that apoptotic tumor cells can stimulate antitumor responses in vitro and possibly in vivo (18, 19, 20, 21).
Surprisingly, little is known regarding the mechanisms by which apoptotic cells inhibit inflammation and adaptive immune responses. Exposure of the anionic phospholipid phosphatidylserine (PS)3 in the outer leaflet of the plasma membrane is one of the most striking and consistent changes on the surface of apoptotic cells (22, 23, 24, 25, 26, 27, 28, 29). It has been known for some time that PS can inhibit macrophage production of proinflammatory cytokines and NO, and that it can block macrophage killing of intracellular parasites (30, 31, 32, 33, 34, 35, 36). Data derived from experiments in vitro and in vivo suggest that PS exposure is crucial for the release of TGF-{beta} by phagocytes that accompanies apoptotic cell recognition and uptake (11, 37, 38). Furthermore, PS-containing liposomes can mimic the response to apoptotic cells by generating TGF-{beta} release (11, 38). Blocking PS on apoptotic cells with annexin V (a Ca2+-dependent, PS-binding protein) has been shown to eliminate the inhibitory effects of the apoptotic cells on the humoral responses (39).
We hypothesized that PS exposed on apoptotic cells was a key factor in inhibiting the inflammatory response required for survival of Ag-specific T lymphocytes and subsequent activation of the adaptive immune response (40, 41). If this is true, PS should inhibit immune responses in vivo. Using three different immunogens and several different assays to measure immune responses, we determined that PS stereo-specifically inhibited responses of Ag-specific CD4+ T and B cells in vivo, and that these effects could be mimicked using an activating Ab directed against the PS receptor. Furthermore, these inhibitory effects could be reversed, at least in part, with anti-TGF-{beta} Ab, implicating TGF-{beta} as an important mediator of the inhibitory response to PS. PS-containing liposomes did not appear to block maturation of bone marrow-derived dendritic cells in response to bacterial endotoxin, TNF-{alpha}, or other stimuli as determined by alternation in expression of surface markers or by ability to present Ag to CD4+ lymphocytes. PS-containing liposomes also failed to block the Ag-induced migration of dendritic cells into regional lymph nodes in vivo. Taken together, these findings suggest that PS inhibits the immune response by inhibiting inflammation in tissue.
-------------------------------------------------------------------------
REQUIRED READING #2 of 5 (abridged) ------
Phosphatidylserine Regulates the Maturation of Human Dendritic Cells
http://www.jimmunol.org/cgi/content/full/173/5/2985
The Journal of Immunology, 2004
Xiao Chen*, Kara Doffek*, Sonia L. Sugg{dagger} and Joel Shilyansky2,*
* Division of Pediatric Surgery and {dagger} Division of Endocrine Surgery, Department of Surgery, Medical College of Wisconsin, Milwaukee, WI 53226
Phosphatidylserine Regulates the Maturation of Human Dendritic Cells
Phosphatidylserine (PS), which is exposed on the surface of apoptotic cells, has been implicated in immune regulation. However, the effects of PS on the maturation and function of dendritic cells (DCs), which play a central role in both immune activation and regulation, have not been described. Large unilamellar liposomes containing PS or phosphatidylcholine were used to model the plasma membrane phospholipid composition of apoptotic and live cells, respectively. PS liposomes inhibited the up-regulation of HLA-ABC, HLA-DR, CD80, CD86, CD40, and CD83, as well as the production of IL-12p70 by human DCs in response to LPS. PS did not affect DC viability directly but predisposed DCs to apoptosis in response to LPS. DCs exposed to PS had diminished capacity to stimulate allogeneic T cell proliferation and to activate IFN-{gamma}-producing CD4+ T cells. Exogenous IL-12 restored IFN-{gamma} production by CD4+ T cells. Furthermore, activated CTLs proliferated poorly to cognate Ag presented by DCs exposed to PS. Our findings suggest that PS exposure provides a sufficient signal to inhibit DC maturation and to modulate adaptive immune responses.
INTRODUCTION
Dendritic cells (DCs),3 which are the most potent professional APCs of the immune system, play an important role in the initiation of adaptive immunity (1). DCs acquire, process, and present Ags derived from pathogenic organisms to activate naive T cells, which mount a specific anti-pathogen immune response. DCs also continuously acquire self-Ags from cells that undergo apoptosis as part of normal cell turnover. However, pathological autoimmune conditions occur rarely, suggesting that the ability of DCs to stimulate self-reactive T cells is tightly controlled. The mechanisms permitting DCs to activate vigorous immune responses to most pathogens and to maintain tolerance to tissue-derived "self" Ags are not fully understood (1, 2). There has been a growing body of evidence suggesting that phagocytosis of apoptotic cells under steady state conditions leads to impaired DC maturation and may induce tolerance (3, 4).
snip
.......Recent studies demonstrate that PS-dependent recognition and ingestion of apoptotic cells by macrophages triggers the release of anti-inflammatory cytokines and inhibits the production of proinflammatory cytokines (20, 21, 22). These studies offer a link between the recognition of apoptotic cells and the physiological consequences of their phagocytosis. Whereas the role of PS in the interaction of apoptotic cells with macrophages and the immunological consequence of PS ligation have been broadly delineated, the role of PS in regulating the phagocytosis of apoptotic cells by DCs and the immunological implication of such interactions are not known. Because of the close lineage relationship between macrophages and myeloid DCs, we hypothesized that PS might play a role in the inhibition of myeloid DC maturation. To test this hypothesis, we prepared large unilamellar liposomes containing PS as a simplified model of cell membrane alterations associated with apoptosis. We examined the effect of PS containing liposomes on DC maturation and immunostimulatory capacity. Our results suggest that PS inhibits the ability of DCs to undergo maturation, secrete IL-12, activate T cells, and stimulate IFN-{gamma}-producing CD4+ T cells.....
snip
DISCUSSION
An emerging paradigm suggests that under steady state conditions, apoptotic cells modulate DC function, inducing immune tolerance to self-Ags and preventing autoimmunity (3, 4, 9). Early apoptosis is characterized by loss of membrane asymmetry and exposure of PS on the cell surface (13). PS recently has been shown to play a central role in the recognition of apoptotic cells by macrophages and may be a signal to secrete anti-inflammatory cytokines (17, 20). However, the effects of PS on the maturation and function of human monocyte-derived DCs, whose lineage is closely related to macrophages, have not been well described. We found that PS, which is recognized specifically by DCs, triggers phagocytosis and plays a key role in modulating DC maturation and function....
....Our findings, for the first time, demonstrate that PS is specifically recognized via PSR expressed on the surface of DCs and triggers phagocytosis....
...Previous reports have suggested that iDCs can induce immune unresponsiveness in vitro and in vivo, possibly due to reduced Ag presentation and T cell costimulation (38, 39, 40, 41). Inhibition of DC maturation by exposure to PS is a potential mechanism for inducing immune unresponsiveness or tolerance. We found that DCs exposed to PS had impaired ability to activate allogeneic T cells (Fig. 5, A and B) and to stimulate IFN-{gamma} production (Fig. 6, A and C). Increasing the ratio of DCs to responders restored the proliferation of allogeneic T cells; however, IFN-{gamma} production by allogeneic CD4+ T cells was still impaired. Increased susceptibility to apoptosis by DCs exposed to PS after LPS treatment could not explain the inability to stimulate IFN-{gamma}-producing T cells in vitro, because IL-4-producing T cells were still induced. Furthermore, exogenous IL-12, which does not affect DC viability, restored IFN-{gamma} production by T cells. The findings suggest that PS did not simply inhibit the ability to activate T cells, but selectively modulated the ability to induce IFN-{gamma}-producing T cells.
....Taken together, these findings suggest that DCs exposed to PS would fail to initiate and may extinguish cellular immune responses.....
...Our findings suggest that PS exposure directly inhibits DC maturation and modulates their ability to activate T cell responses. PS is specifically recognized by DCs and triggers phagocytosis via the PSR. Our findings suggest that PS modulates the adaptive immune response at three different levels: 1) PS inhibits survival, Ag presentation, and costimulation by DCs, leading to ineffective T cell proliferation; 2) PS inhibits IL-12p70 secretion by DCs, diminishing the ability to stimulate IFN-{gamma}-producing T cells characteristic of Th1 responses; and 3) DCs exposed to PS have reduced ability to stimulate the proliferation of activated CD8+ T cells, even in the presence of abundant Ags. PS may synergize with additional signals, such as CD200, IL-10, and TGF-{beta}, expressed by apoptotic, inflammatory, or stromal cells (20, 22, 50, 51, 56, 65, 66). Further understanding of the mechanisms by which PS modulates DC function may lead to the development of effective immunotherapies for autoimmune diseases and for cancer.
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REQUIRED READING #3 of 5 (abridged) ------
Apoptotic cells, through transforming growth factor-beta, coordinately induce
anti-inflammatory and suppress pro-inflammatory eicosanoid and NO
synthesis in murine macrophages.
Celio G. Freire-de-Lima∗†‡2, Yi Qun Xiao†‡, Shyra J. Gardai†, Donna L. Bratton†, William P.
Schiemann† and Peter M. Henson†
*Instituto de Biofísica Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro,
RJ 21944-970, Brazil
†Program in Cell Biology, Department of Pediatrics, National Jewish Medical and Research
Center, 1400 Jackson Street, Denver, Colorado 80206
Running title: TGF-beta modulates inflammatory eicosanoids
http://www.jbc.org/cgi/reprint/M605146200v1
--------------
In the studies reported here, we showed that the
TGF-beta induction by apoptotic cells was
dependent on exposed PS
...............
These results strongly
suggest that the apoptotic cell inhibition of
pro-inflammatory mediator production is
pleiotropic and significantly dependent on the
stimulation of TGF-beta production.
...............
The
implication is that recognition of PS drives the
production of TGF-beta and the downstream antiinflammatory
responses reported herein.
..............
The induction of TGF-beta itself
could be attributed to exposed
phosphatidylserine on the apoptotic cells,
which therefore, appears to drive the
balanced inflammatory mediator responses.
..............
Apoptotic cells are rapidly engulfed by
adjacent tissue cells or macrophages before
they can release pro-inflammatory/proimmunogenic
intracellular contents. In
addition, recognition of the apoptotic cells is
actively anti-inflammatory and antiimmunogenic
with generation of antiinflammatory
mediators such as
transforming growth factor-beta (TGF-beta) and
anti-inflammatory eicosanoids. Here, we have
investigated the role played by the induction
of TGF-beta in the coordinate expression of antiinflammatory
eicosanoids or PPARγ and in
the suppression of pro-inflammatory lipid
mediators and nitric oxide (NO).
................
As a
cell becomes apoptotic, it is generally removed
in situ by near-neighbor cells or macrophages in
a quiet, almost invisible fashion; that is, the
process does not induce a local tissue reaction.
In fact, recognition and removal of apoptotic
cells is normally both anti-inflammatory and
anti-immunogenic (6-9).
...............
The interaction and recognition are triggered by
surface changes on the apoptotic cells.
.................
there is considerable evidence to implicate PS as
the main stimulus for the anti-inflammatory or
anti-immunogenic effects (6-8,14-16).
...............
A major anti-inflammatory mediator induced in
response to apoptotic cells, mAb217 or PS
liposomes is TGF-beta (6,8,16). Blockade of TGF-
beta has been shown to reverse the suppressive
effects of apoptotic cells or PS in vivo on either
inflammation or adaptive immunity (7,8).
................
A key issue, therefore, is whether apoptotic cellinduced
TGF-beta, acting in an autocrine/paracrine
fashion, mediates the alterations in eicosanoid
generation. By use of a dominant negative TGF-
beta receptor construct we have been able to show
that apoptotic cells stimulate via their induction
of active TGF-beta, a co-ordinate production of
generally anti-inflammatory, and simultaneous
inhibition of generally pro-inflammatory,
eicosanoids.
................
Results
Apoptotic cells or antibody to PSRS on murine
macrophages stimulate production of TGF- beta
and concomitant blockade of LPS-induced
TNF alpha, NO and iNOS.
.................
Discussion
Apoptotic cells are known to induce an antiinflammatory
and anti-immunogenic response,
in part mediated by their induction of active
TGF-beta in responding cells. Here we show that
the effect of the apoptotic cells is to drive a
complex coordinated inhibition of potentially
inflammatory mediators along with induction of
potentially anti-inflammatory molecules in
macrophages that are orchestrated by the TGF-beta
production.
.................
The observations required the demonstration of
TGF-beta production in response to the apoptotic
cells – shown earlier by numerous investigators
and confirmed herein. A number of ligands have
been demonstrated on apoptotic cells that can
interact with a number of “receptors” on
responding cells, in this case macrophages.
Additionally there are a large group of “bridge”
molecules (see ref. 39) that can link the
apoptotic cell ligands to the receptors. We have
suggested that two important ligands are
phosphatidylserine (PS) and calreticulin. The
latter, as well as the collectin family of bridge
molecules (40) has been suggested to interact
with LRP as a receptor and, in isolation, seems
to induce a more pro-inflammatory response
(5,13). On the other hand, PS and its receptors
and possibly some or all of its bridge molecules
appear to induce the anti-inflammatory effects
and, in most cases, to act in a dominant fashion
in the normal response to apoptotic cells.
Necrotic cells are usually thought to be proinflammatory
(see for example 9,15) and may
have reversed this PS-driven dominance. Other
studies that have suggested that apoptotic cells
can in some circumstances act in a proinflammatory
fashion may also reflect variations
in balance between pro-inflammatory (e.g. LRP)
versus anti-inflammatory (e.g. PS driven)
responses.
................
The results indicate a complex effect of
apoptotic cells acting through release of TGF-beta
to upregulate generally anti-inflammatory
mediators and inhibit the production of proinflammatory
molecules.
--------------------------------------------------------------
REQUIRED READING #4 of 5 (abridged) ------
The influence on the immunomodulatory effects of dying and
dead cells of Annexin V
The Journal of Leukocyte Biology, Jan, 2007
http://www.jleukbio.org/cgi/rapidpdf/jlb.0306166v1
-----------
Abstract: Apoptotic and necrotic cells expose
phosphatidylserine (PS). This membrane modifi-
cation ensures a swift recognition and uptake by
phagocytes of the dying and dead cells. Annexin
V (AxV) preferentially binds to anionic phospholipids
and thereby, modulates the clearance process.
First, we analyzed the influence of AxV on
the immunogenicity of apoptotic cells. The addition
to apoptotic cells of AxV prior to their injection
into mice increased their immunogenicity
significantly. Next, we studied the influence of
endogenous AxV on the allogeneic reaction
against apoptotic and necrotic cells. To preserve
heat-labile, short-lived “danger signals,” we induced
necrosis by mechanical stress. Wild-type
mice showed a strong, allogeneic delayed-type
hypersensitivity (DTH) reaction. In contrast,
AxV-deficient animals showed almost no allogeneic
DTH reaction, indicating that endogenous
AxV increases the immune response against dead
cells. Furthermore, AxV-deficient macrophages
had a higher immunosuppressive potential in
vitro. Next, we analyzed the influence of AxV on
chronic macrophage infection with HIV-1,
known to expose PS on its surface. The infectivity
in human macrophages of HIV-1 was reduced
significantly in the presence of AxV. Finally, we
show that AxV also blocked the in vitro uptake by
macrophages of primary necrotic cells. Similar
to apoptotic cells, necrotic cells generated by
heat treatment displayed an anti-inflammatory
activity. In contrast, mechanical stress-induced
necrotic cells led to a decreased secretion of
IL-10, indicating a more inflammatory potential.
From the experiments presented above, we
conclude that AxV influences the clearance of
several PS-exposing particles such as viruses,
dying, and dead cells. J. Leukoc. Biol. 81:
000–000; 2007.
In healthy situations, cells dying by apoptosis maintain their
membrane integrity until they get cleared. Cell shrinkage leads
to formation of apoptotic bodies containing organelles. Nevertheless,
the dead corpse still has an important message: “No
inflammation, please!”
We were asking the question of whether an interference with
the anti-inflammatory clearance by macrophages of apoptotic
cells, mainly mediated by PS recognition, consecutively restores
the immunogenicity of apoptotic cells in vivo. For this
purpose, mice were immunized with apoptotic cells in the
presence or absence of the PS-binding protein AxV. Using
AxV-deficient mice [21], we further analyzed the physiological
function of AxV in the induction of an immune response
against apoptotic and necrotic cells. PS is also expressed on
monocytes as part of their differentiation program [22]. Many
viruses including HIV cause extensive apoptosis, and infected
monocytes/macrophages therefore express elevated levels of
PS, which consecutively, can also be found in the outer membrane
of the enveloped retrovirus [23]. Using an in vitro culture
system, we examined whether, like the swift uptake of apoptotic
cells, the AxV can also block the silent entry of HIV-1 into
human macrophages. To better understand the mechanism how
PS exposing AxV-binding particles modulates the immune
response, we examined the cytokine secretion of activated
human macrophages and peritoneal macrophages from AxVdeficient
mice after contact with dying and dead cells.
DISCUSSION
Apoptosis is defined as programmed cell death or cellular
suicide, whereas necrosis arises as a result of a violent external
stimulus. A hallmark of apoptotic cells, in contrast to necrotic
ones, is that they maintain their membrane integrity over time.
Thus, the release of intracellular components, which could
damage the surrounding tissue, induce inflammation, or elicit
immune responses, is avoided [26]. To ensure immediate recognition
and uptake by phagocytes, apoptotic cells undergo
early membrane modifications. One such event is the exposure
of PS in the outer leaflet of the plasma membrane associated
with a loss of phospholipid asymmetry. Phagocytes interact
with PS on apoptotic cells mainly through secreted bridging
adaptor proteins, also called opsonins. The latter are important
for a high-capacity clearance of apoptotic cells [27].
The recognition of exposed PS triggers the release of immunosuppressive
cytokines [14, 15, 28], which quench inflammation
and prevent the maturation of antigen-presenting dendritic
cells (DC). Apoptotic cells per se do influence the production
of soluble pattern recognition receptors such as pertussis toxin
3 by maturing DC [29]. Furthermore, the opsonization of apoptotic
cells by soluble factors influences their antigen presentation
by DC and thereby, modulates their immunogenicity
[30]. Recently, it was discussed that alterations of the plasma
membrane phospholipid distribution have important influences,
not only for cell clearance but also for the execution of
apoptosis [31].
AxV is a natural-occurring, specific ligand for PS and may
consequently interfere in vivo with the immunosuppressive
effects of apoptotic cells. We showed that the immunogenicity
of apoptotic cells could be restored by the addition of AxV.
During apoptotic as well as necrotic cell death, autoantigens
are cleaved or otherwise modified, and these modifications may
render cryptic epitopes immune-dominant (reviewed in ref.
[32]). When interfering with the clearance of dying cells, DC
may acquire modified autoantigens such as apoptotic nuclei
and chromatin, and consequently, autoreactive T cells can be
activated. This may also lead to chronic autoimmunity, as is the
case in SLE [24]. It was also shown that an impaired clearance
of dying tumor cells can lead to tumor rejection. AxV decreased
apoptotic cell uptake by peritoneal macrophages and
concomitantly increased their uptake by CD8/11c DC [33].
When AxV binds to apoptotic cells, it “crystallizes” as an
extended two-dimensional network. It has an autocrine function
and activates away from cell entry. This results in the
internalization of the PS-expressing membrane patches from
the surfaces of apoptotic macrophages [35]. We have shown
previously that AxV shows positive cooperativity for PS binding
on membranes of apoptotic and necrotic but not of viable
cells. We suggested that phagocytes can differentiate between
dying and viable cells by means of PS clustering and consecutively,
by the lateral mobility of the cellular membranes [36].
PS-mediated phagocytosis of apoptotic cells suppresses inflammatory
signals such as TNF-, IFN- , and NO and also triggers
the production of TGF-, an anti-inflammatory cytokine
[15]. We have previously shown that necrotic cells, like apoptotic
ones, can also engage CD36 and a surface receptor
recognized by mAb 217G8E9. They thereby mediate antiinflammatory
signals [12]. Here, we show that necrotic cells
induced by heat treatment promote the release of anti-inflammatory
cytokines by LPS-activated macrophages, as is the case
for apoptotic cells. Heat-induced necrosis destroys heat-labile
and short-lived danger signals. The uptake of the necrotic cells
then becomes anti-inflammatory. In contrast, mechanical
stress-induced necrotic cells led to a decreased secretion of the
anti-inflammatory cytokine IL-10 and consecutively, displayed
a more immunostimulatory phenotype. We conclude that the
proinflammatory properties of necrotic cells depend on the
inductor of necrosis. Furthermore, we added AxV to this experimental
setting and found a significant, further up-regulation
of IL-10 secretion in the case of heat-necrotized cells but
not in the case of stress-induced necrotic cells (not shown),
further confirming the higher proinflammatory potency of mechanical
stress-induced necrotic cells when compared with
heat-induced necrosis.
The primary force of the immune system is the need to detect
and protect against danger [37]. One mode of action of danger
signals is to stimulate the maturation and activation of DC
necessary for the initiation of primary and secondary immune
responses. Endogenous danger signals, released by tissues
undergoing stress, damage, or abnormal death, and also exogenous
danger signals, elaborated by pathogens, can contribute
to this stimulation. Some endogenous danger signals, which
have been discovered recently are heat-shock proteins, nucleotides,
reactive oxygen intermediates, extracellular matrix
breakdown products, neuromediators, cytokines such as the
IFNs [38], as well as uric acid [39], ATP [40, 41], and HMGB1
[16, 42], which as well as its best-characterized receptor for
advanced glycation end products, is important for the maturation
of human plasmacytoid DC [43] and also controls T cell
activation [44]. Furthermore, the release of intracellular factors
from necrotic tumor cells can promote reactive angiogenesis,
stromal proliferation, and local immune suppression [45]. Future
work has to be focused strongly on all such “alarmins”
[46], which signal the body: “Attention, tissue damage has
occurred!”
Many viral infections (such as HIV) lead to the release of
several proinflammatory cytokines and to extensive apoptosis.
The latter may contribute to the impaired immune response
accompanying such infections [50, 51]. Recently, it has been
shown that PS can be detected at the surface of HIV-1 and that
AxV can be used to enrich these virus particles. Furthermore,
the infection by HIV-1 strains of monocytes can be compromised
upon the addition of AxV during the infection process
[23]. Here, we demonstrated that clinically relevant, chronic
infections of HMDM with HIV-1 isolates can be inhibited by a
single application of AxV. In addition, Ma et al. [52] showed
that Annexin II is necessary for HIV-1 uptake into human
macrophages. This HIV-1 PS interaction with Annexin II could
be disrupted by a secretory leukocyte protease inhibitor [52].
Taken together, AxV efficiently blocks the silent entry of
HIV into macrophages as well as the swift clearance of apoptotic
and necrotic cells. The disturbed, PS-dependent clearance
by macrophages of apoptotic cells leads to the accumulation
of the latter and to the occurrence of late apoptotic cells,
which have lost their membrane integrities. The proinflammatory
cytokine profile of the late clearance and endogenous
danger signals released from cells, which have lost their membrane
integrity, build a proinflammatory microenvironment. DC
may then pick up antigens derived from the dying cells in a
proinflammatory milieu and present the cell-derived antigens
together with costimulation (Fig. 5). We showed that AxV
increased the immunogenicity of apoptotic cells significantly.
In addition, immunization with mechanical stress-induced necrotic
cells was used to mimic the above-mentioned scenario.
Only in the presence of endogenous AxV (WT animals) was a
specific immune response against the dead cells to be observed.
Furthermore, endogenous AxV led to a decreased
secretion of IL-10 in peritoneal macrophages in response to
mechanical stress-induced necrotic cells. Examinations of the
in vitro mechanisms underlying the observed effects revealed
that mechanical stress-induced necrotic cells led to an inflammatory
modulation of macrophages in contrast to apoptotic
cells and heat-induced necrotic ones. In conclusion, apoptotic
and necrotic cells strongly influence the immune response.
AxV is an important modulator of this interaction. It inhibits
certain viral infections and increases the immune response
against tumor cells and more general, that against dying and
dead cells.
-----------------------------------------------------------------
REQUIRED READING #5 of 5 (abridged) ------
Cancer Cell Immune Escape and Tumor Progression by Exploitation
of Anti-Inflammatory and Pro-Inflammatory Responses
Cancer Biology & Therapy 4:9, 924-933, September 2005
http://www.landesbioscience.com/journals/cbt/article/kim4-9.pdf
-----------
Apoptotic cells can be eliminated by phagocytosis, which is mediated by antigen-
presenting cells (APCs), such as macrophages and dendritic cells (DCs), through
phosphatidylserine (PS) on apoptotic cells and phosphatidylserine receptor (PSR) on
APCs. The phagocytosis of apoptotic cells by macrophages is strictly regulated by not
only the inflammatory reaction, but also by an increase in anti-inflammatory factors such
as IL-10, TGF-b, and prostaglandin E2 (PGE2), leading to an anti-inflammatory situation,
whereby apoptosis contributes to a noninflammatory response. However, because PS and
PSR are expressed in cancer cells, shed soluble phosphatidylserine (sPS) can interact with
the PS receptor on macrophages, which promotes an anti-inflammatory response to
macrophages that may lead to immune escape. The sPS derived from cancer cells also
reacts with the PSR on the cancer cells to produce IL-10, TGF-b, and PGE2, which can
cause suppression of anti-tumor immunity through the anti-inflammatory response to
macrophages, which produces tumor-associated macrophages. Furthermore, sPS and
TGF-b inhibit the maturation of immature DCs, resulting in a functional inhibition of DCs.
The potential roles of PS and PSR in cancer cells and macrophages in immune escape
mediated by sPS and anti-inflammatory factors are discussed, which may explain their
dual regulation of anti- and pro-inflammatory responses during tumor progression.
-----------------
the PS/PSR-mediated
anti-inflammatory response can be induced by soluble phosphatidylserine (sPS) derived
from cancer cells. The sPS can interact with either APCs or PSR on cancer cells, resulting
in the production of IL-10, TGF-b and PGE2, whereby the function of APCs is inhibited.16,17
Thus, the production of anti-inflammatory cytokines mediated by sPS/PSR on APCs and
cancer cells may promote immunosuppression, which impairs macrophage cytotoxicity
and DC function. The impairment
prevents an immune response in the
tumor microenvironment and facilitates
tumor progression and metastasis.18,19
-------------
The shift
to an anti-inflammatory response to immune cells mediated by
TAM in response to sPS from cancer cells may result in the inhibition
of maturation of DCs and their migration to a primary lymphoid organ
for activation of T-cells.
----------------
The
production of soluble factors such as IL-10 and TGF-b helps cancer
cells to avoid immune recognition through inhibition of development
and activity of immune cells.
-----------------
Given that the immunosuppressive mediators such as IL-10,
TGF-b, and PGE2 play an important role in promoting immune
escape in the microenvironment of cancer cells, the release of these
cytokines take place from TAMs as well as from cancer cells.42
-----------------
vascular endothelial cells in tumors
externalize PS to their luminal surface, whereas PS is absent from the
external surface of vascular endothelial cells in normal tissues.19 (Thorpe/Ran, j.)
-------------
the sequential immune response by TAM
and DCs can be abrogated by sPS derived from cancer cells. The
enforced anti-inflammatory response by sPS-not only by interaction
with the PSR on TAM but also with the PSR on immature DCs to
inhibit their maturation-may cause immune escape and tumor
proliferation. Furthermore, the sPS derived from cancer cells binds
to these cells’ own PSR, resulting in the production of IL-10,
TGF-b, and PGE2 in the tumor microenvironment and facilitation
of tumor proliferation.
---------------
During the anti-inflammatory response, the TGF-b derived from
TAM prevents the maturation of antigen-presenting DCs, thereby
inhibiting the activation of natural killer cells and CTLs.86 In addition,
the TGF-b promotes the proliferation of stromal cells such as fibroblasts
and macrophages and induces them to secrete angiogenic and
cell survival factors that stimulate tumor proliferation through
NF-kB, which is activated by Akt.52 These stromal cells also produce
Th2 cytokines, such as IL-4 and IL-10, as well as PGE2 as a
result of TGF-b secretion.
-----------------
Thus, the production of
IL-10, TGF-b, and PGE2 from TAM mediated by sPS or hydroxide
plays a critical role in immune escape.
-----------
j
Upstream Interference of TGF-beta:
what was that again?
---------------------------------------------
* "interference with immunosuppressive mechanisms could be attempted upstream"
* "interfering with the pathway utilized by tumor cells to promote MSC in vivo generation"
* "As we reported that exosomes released by melanoma cells are likely responsible for the induction of CD14+HLA-DR–/lo cells secreting TGF-ß"
* "thwarting the process of exosome production could represent a tool for interrupting the immunosuppressive circuits established by tumor cells and for retrieval of cancer immunity"
http://jco.ascopubs.org/cgi/content/full/25/29/4696
--------
Evolution has favored pathogenesis that resembles apoptosis,
j
TGF-beta, T regs, Bavituximab........
As you know, Bavituximab therapy is proven to shift the cytokine environment away from TGF-beta.
first this: It's recent...
-----------------
Tregs and rethinking cancer immunotherapy
http://www.jci.org/cgi/content/abstract/117/5/1167
Tyler J. Curiel
San Antonio Cancer Institute, University of Texas Health Sciences Center, and Cancer Therapy & Research Center, San Antonio, Texas, USA.
Address correspondence to: Tyler J. Curiel, San Antonio Cancer Institute, University of Texas Health Sciences Center
Tumors express antigens that should induce immune-mediated rejection, but spontaneous rejection of established tumors is rare. Recent work demonstrates that one reason for the lack of tumor rejection is that tumors actively defeat host immunity. This concept forces us to rethink current approaches to harnessing potent, specific host immunity to battle cancer, most of which are based on the paradigm that inducing more antitumor immune cells alone is therapeutic. However, as I discuss in this Personal Perspective, a newer paradigm predicts that reducing tumor-driven immune suppression will be clinically beneficial. CD4+CD25+ Tregs are one mechanism of tumor-driven immune evasion that provide prototypical targets for testing novel anticancer treatment strategies within the newer paradigm.
---------
Then this Must-Read "reply", on October 10th, 2007 ...................
excerpts below -
Journal of Clinical Oncology, Vol 25, No 29 (October 10), 2007
CORRESPONDENCE
In Reply
http://jco.ascopubs.org/cgi/content/full/25/29/4696
Paola Filipazzi, Chiara Castelli, Valenti Roberta, Veronica Huber, Manuela Iero, Lorenzo Pilla, Licia Rivoltini
Unit of Immunotherapy of Human Tumors, Fondazione IRCCS Istituto Nazionale Tumori, Milan, Italy
Giorgio Parmiani
Unit of Immunobiotherapy of Solid Tumors S. Raffaele Scientific Institute, Milan, Italy
A growing body of evidence currently supports the role of myeloid suppressor cells (MSC) as key mediators of immunosuppression in tumor-bearing animals.1 Nevertheless, the analysis of the actual relevance of this mechanism in cancer patients has so far been penalized by the variability of phenotypic and functional hallmarks that these cells appear to display in a human setting. In our study, we identify a monocyte subset (CD14+ human leukocyte antigen-DR [HLA-DR]–/lo transforming growth factor-ß [TGF-ß]–secreting cells) that may indeed represent an MSC population in patients with advanced melanoma. The finding acquires more relevance considering that melanoma is one of the human tumor histotypes mostly involved in immunotherapy studies because of its unique immunogenic properties.2 Having defined features for the identification of MSC in patients with melanoma should allow us in the near future to understand the relevance that this cell subset plays in restraining antitumor immune responses.
.......
As correctly pointed out by Ferretti, TGF-ß is a pathway shared by different regulatory immune mechanisms. Indeed, regulatory T cells (Treg) exert their immunosuppressive activity through mechanisms including cell-cell contact and/or the production of soluble factors such as interleukin-10 or TGF-ß,3 as we are presently observing in advanced melanoma patients (Castelli et al, unpublished observation, 2007). Recent studies in experimental models have linked MSC to Treg, showing that the conversion by tumor cells of dendritic cells into MSC induces bioactive TGF-ß secretion, which in turn stimulates Treg expansion and subsequent suppression of T cell–mediated immune responses.4
........
from our study as well as from several other works,7,8 TGF-ß is emerging as a cytokine playing a pivotal role in immunosuppression of cancer patients. Indeed, both MSC and Treg seem to use this pathway to shut down antitumor T cell responses; therefore, interfering with the activity of this cytokine could represent a key strategy to cancer therapy.
.......
New molecules such as antisense oligonucleotides for TGF-ß, small drug-molecules that inhibit TGF-ß receptor I kinase, and anti–TGF-ß antibodies have shown promising results in preclinical studies and are presently entering the clinical phase of evaluation.9
......
Alternatively, the interference with immunosuppressive mechanisms could be attempted upstream, interfering with the pathway utilized by tumor cells to promote MSC in vivo generation. As we reported that exosomes released by melanoma cells are likely responsible for the induction of CD14+HLA-DR–/lo cells secreting TGF-ß, thwarting the process of exosome production could represent a tool for interrupting the immunosuppressive circuits established by tumor cells and for retrieval of cancer immunity.
----------
j
Oh, re: HIV, & CMV, & RSV
One important thing that some might not have noticed, and has not yet been discussed on this board -
As Dr. Wahl from NIH points out, all three of those virus families use PS on the viral envelope to enter cells via annexin II, (SLPI).
http://www.jem.org/cgi/content/full/200/10/1337
Recall - (also from Thorpe's UTSW page) -
* Bavituximab treatment of mice with lethal murine cytomegalovirus infections gives 100% survival.
(and that was in an 80/20 experiment, where ~ 80% of control animals die.)
* Thorpe: "No observable toxicities are associated with bavituximab therapy. "
--------
j
steve -
I'm not sure what the first dose amount is. Without knowing that, it's hard to make any 'educated guesses'. I'm assuming it's at least 0.3, but have note heard yet.
I do expect impressive results against HIV based on bavi's multiple MOA's-
(this is from Phil Thorpe's UTSW page) -
* We have found that PS becomes exposed on the external surface of virally infected cells,
* Bavituximab achieves its protective effects by directing host cells to kill the virally-infected cells
* and by causing opsonization and clearance of virions from the bloodstream.
* In addition, the antibody appears to negate PS-mediated immunosuppressive signals
(which is the fascinating MOA that I post all the corroborative papers about)...
------------
j
nice to see in print - "Analysis of Cytokine Profile Following Treatment Supports Proposed Immunomodulatory Mechanism of Action"
http://biz.yahoo.com/prnews/071105/lam124.html?.v=16
free,
Yes, Kornbluth put it together pretty early. But look at all the (previous) work he cites which inspired his review.
Peter Henson, Valerie Fadok, Martin Herrmann, Joel Shilyansky, Udo Gaipl, Alan Schroit, Andrew Henderson, Robert Schlegel, and many, many others have made many further discoveries since then that further defined (in greater detail) the role of PS and various PS receptors in altering immune functions.
Now Haynes comes out with this in Sept, along with the most recent CHAVI clinical study (#12) that looks directly at this area. (Meanwhile Haynes is isolating antiphospholipid antibodies from lupus patients that are successful in neutralizing HIV, (CHAVI study #5), as discussed in his most recent CHAVI update.
-------
j
Kornbluth / Haynes -
With Haynes' September presentation in Seattle on the immunomodulatory effects of PS-exposing apoptotic debris accumulating fast in early HIV infection, and dampening the immune system's fight against the virus, this review by Richard Kornbluth becomes very relevant.
This was written back when it was still thought that apoptotic cells and their microparticles were immunologically neutral. They're not. Kornbluth was right.
It's only recently we've been able to actually safely target PS, (Thorpe/Ran).
It's only recently that the safety details have become clear, (Schroit/Luster).
-------------------
--------
j
good article on the anti-CTLA-4 mabs -
http://members.forbes.com/global/2007/1112/128.html?partner=yahoomag
Targeting Melanoma
Robert Langreth 11.12.07
A new arsenal of therapies is aimed at a widespread and lethal skin cancer.
When Edward Watson found a black spot on his left forearm in May 2004, the physician, then 39 years old, realized that it was the return of the melanoma that he had previously been treated for. This time it was beyond a skin cancer. Tumors had spread to his back, spine, adrenal gland, lung, ribs, pelvis and both hips. He took a positron emission scan, and, he says, "I lit up like a Christmas tree." His surgeon told him he had eight months to live.
Watson quit his job for Pfizer (nyse: PFE - news - people ) in Australia, moved back to his native New Zealand and prepared to die. Then former Pfizer colleagues told him about a new drug, tremelimumab, in early trials. It was an antibody that primes the immune system to attack and kill tumors.
A few weeks later Watson was on a plane to the U.S. to start treatment at UCLA. The antibody produced a rash on his chest and made him lethargic. By fall he noticed that the tumor on his back was shrinking; doctors removed it and found dead cancer cells. He continued flying back quarterly to see UCLA oncologist Antoni Ribas for infusions. By June 2006 the tumors were gone. Watson remains in remission and continues to take the drug every six months. He recently started a business. "This drug has saved my life; there are no two ways about it," he says.
Watson is one of the first to benefit from a new generation of melanoma drugs working their way through human trials. The drugs, in testing at Pfizer, Bristol-Myers Squibb (nyse: BMY - news - people ) and elsewhere, may improve upon medicine's dismal track record of treating the most deadly form of skin cancer. One blocks the mutant proteins inside melanoma that cause their rampant growth. Another prods the immune system into attacking and destroying the cancer. Neither approach is likely to be a cure on its own; a combination of therapies may be needed.
Melanoma, a cancer of the skin's melanocytes, or pigment cells, hits 60,000 Americans each year and kills 8,000 of them. It can strike in the prime of life and is one of the few cancers whose incidence is exploding, for unclear reasons. Risk factors include sunburn, fair skin and having lots of moles. Most cases are localized and can be cured with surgery. But when melanoma metastasizes, watch out. It "tends to spread to many, many parts of the body at an alarming rate," says Memorial Sloan-Kettering Cancer Center melanoma expert Jedd D. Wolchok. Chemotherapy helps only 10% of metastatic melanoma patients, usually for just a few months.
Until recently researchers had little clue what molecular changes drive melanoma's rapid growth. But that has changed in a flurry of basic biology findings. "In terms of understanding what makes melanoma tick, in the past five years there has been an utter revolution," says Keith Flaherty, a physician at the University of Pennsylvania.
In 2002 gene researchers in the U.K. discovered that two-thirds of melanomas have a mutation in a growth-promoting gene inside skin cells called BRAF. The mutation causes the BRAF protein to become stuck in the "on" position, so it constantly sends a signal to the nucleus that it is time to proliferate. BRAF blockers are now in early-stage human trials at Novartis (nyse: NVS - news - people ) and separately at Roche, which works with partner Plexxikon. AstraZeneca (nyse: AZN - news - people ) is in midstage trials with 180 melanoma patients for a drug that hits a related target called mitogen-activated protein kinase kinase. "Every company I know of is interested in this," says Plexxikon Chief Executive Peter Hirth.
Therapies that trick the immune system into attacking melanoma are further along. Such immune system boosters have the potential to treat many types of cancer, but melanoma is one of the prime initial targets because it is one of the few cancers known to go into spontaneous remission on its own, indicating a possible immune response at work. The immune system activator interleukin-2 helps 15% of advanced melanoma cases and cures a few, but it produces such devastating side effects that patients must be hospitalized.
Pfizer's drug tremelimumab and Bristol-Myers Squibb's ipilimumab are antibodies to a protein called CTLA-4 (cytotoxic T-lymphocyte antigen-4) that acts as an emergency brake to prevent killer T cells from attacking healthy tissue. The antibodies bind to the CTLA-4, found on a cell's surface, and shut off the brake. Killer T cells then attack the cancer cells. Both drugs are in final-stage trials on hundreds of melanoma patients.
Much credit for the concept goes to immunologist James Allison, now at Sloan-Kettering in New York. In the mid-1990s he theorized that CTLA-4 might prevent the immune system from mounting an effective response against tumors. Others were skeptical. But Allison showed in 1996 that he could shrink tumors in mice by injecting them with antibodies to CTLA-4.
Both Pfizer and Medarex (nasdaq: MEDX - news - people ), a biotech firm in Princeton, New Jersey, subsequently produced human antibodies to CTLA-4 and began testing them in patients a few years later. In 2005 Bristol-Myers Squibb paid Medarex $50 million in cash plus up to $480 in payments contingent on the success of Medarex's antibody.
At a meeting of cancer specialists last June Bristol-Myers and Medarex reported their drug shrank tumors in 46, or 13%, of 356 melanoma patients. The Pfizer antibody shrank melanomas in 7 of 84 patients in a midstage trial. The success rates were modest, but cancer doctors say that some patients may have had delayed responses. In some people tumors started to regress months after they had been declared treatment failures, says Bristol-Myers Vice President Renzo Canetta.
UCLA's Ribas calls the response rates "very low" and cautions that the anti-CTLA-4 drugs are just a first step. But even if the drugs improve survival only minimally, they are likely to be approved, he says. Bristol-Myers and Medarex are expected to finish key trials this fall. RBC Capital Markets analyst Jason Kantor pegged the odds of disappointing results "relatively high" in a recent report and rated Medarex an underperform; if the response rate is under 10%, it would make near-term approval "iffy," he says. Side effects of the drugs can include inflammation of the colon, thyroid or pancreas, or other autoimmune problems.
One reason for the limited response rate may be that some patients' T cells do a poor job of recognizing melanoma. To improve this situation, researchers are combining new antimelanoma vaccines with anti-CTLA-4 drugs. The idea is that the vaccines will train T cells to spot cancer, while the antibody will make sure the T cells remain activated long enough to do their dirty work.
Sharon Belvin was one of the first to try such a combination therapy. In May 2004, just a week before her wedding, she had developed a melanoma metastasis in her left lung. Belvin was only 22. The tumor grew through her chest cavity underneath her collarbone. Various chemo drugs and interleukin-2 produced nerve damage and other nasty side effects and didn't solve the problem. By June 2005 she had tumors in both lungs and could barely breathe or walk. Then Wolchok put her in a trial testing ipilimumab with an experimental Medarex vaccine. After only four treatments the tumors started to melt away. They were gone by mid-2006. The Jamesville, North Carolina resident has been off therapy for a year and is pregnant with her first child, a girl due Feb. 10.
--------
j
Sharon Wahl of NIH: PS & HIV...
http://www.jem.org/cgi/content/full/200/10/1337
Secretory Leukocyte Protease Inhibitor Binds to Annexin II, a Cofactor for Macrophage HIV-1 Infection
snips from this NIH work -
"PS is not encoded by HIV-1, but rather is acquired from its host cell membrane as it exits the cells (26). During viral assembly at the cell surface or within cytoplasmic vesicles, cell membrane components become incorporated into the new viral coat along with virally encoded gp120/gp41. The resulting mosaic HIV-1 envelope represents a lipid bilayer with a unique cholesterol/phospholipid composition, embracing viral and host molecules, including PS."
......
"Our data favor a model in which PS in the viral coat interacts with annexin II on the surface of macrophages subsequent to recognition-specific gp120 interactions with CD4 and the chemokine coreceptors that instigate coiled coil exposure of gp41 fusion domains to interact with the lipid bilayer of the target cell (10, 30), and then engage an annexin II–dependent fusion/entry pathway leading to productive infection"
......
"Annexin II on macrophages may preferentially facilitate entry of virions expressing PS acquired during exit from prior macrophage hosts or from T cells undergoing apoptosis.."
......
" It is conceivable that PS–annexin II interactions in the cytoplasmic vesicles and late endosomes of macrophages, where structural assembly of virions occurs (12, 43) and annexin II is found (28), not only serve as a construction scaffolding, but also as a tether to retain virions intracellularly in a covert maneuver to avoid detection at the cell surface. Because the S100A10 component of the annexin II complex has been shown to facilitate arbovirus exocytosis (44), such a role in HIV-1 egress might also be considered. Annexin II/PS may also contribute to the host cell–derived cloak of the hypothetical Trojan exosomes that subversively deliver retroviral particles to nearby cells (45), thus a co-conspirator with HIV-1 both going in and coming out."
.......
"The persistence of HIV-1 infection, coupled with its incredible mutation rate and insular reservoirs, focuses attention on host cell constituents usurped by the virus as potential intervention targets"
......
"Clearly, viral pathogens other than HIV-1, including CMV and respiratory syncytial virus (19, 20), also take advantage of target cell annexin II to enhance their infectivity and/or dissemination, and furthermore, bacteria trigger annexin II recruitment to their attachment sites (27), all suggesting its broader involvement in microbial entrance and pathogenesis"
longer excerpts:
Abstract
The distribution of secretory leukocyte protease inhibitor (SLPI) at entry portals indicates its involvement in defending the host from pathogens, consistent with the ability of SLPI to inhibit human immunodeficiency virus (HIV)-1 infection by an unknown mechanism. We now demonstrate that SLPI binds to the membrane of human macrophages through the phospholipid-binding protein, annexin II. Based on the recent identification of human cell membrane phosphatidylserine (PS) in the outer coat of HIV-1, we define a novel role for annexin II, a PS-binding moiety, as a cellular cofactor supporting macrophage HIV-1 infection. Moreover, this HIV-1 PS interaction with annexin II can be disrupted by SLPI or other annexin II–specific inhibitors. The PS–annexin II connection may represent a new target to prevent HIV-1 infection.
...................
Annexin II Interacts with PS.
How annexin II might support HIV-1 infection of macrophages was a mystery, but a recent study reporting that HIV-1 membranes contain PS (14) provided a potential clue. Although no binding partner for HIV-PS had been identified, we surmised that annexin II, a phospholipid-binding protein, might be a candidate. In this regard, direct binding of HIV-1 to plate-bound annexin II, but not irrelevant proteins, was demonstrated (Fig. 5 A). Moreover, to verify an HIV-PS–macrophage annexin II connection, we exposed HIV-1 to excess soluble annexin II to bind/coat viral PS before addition to macrophages, and this markedly suppressed subsequent infection (Fig. 5 B), compatible with inhibition of infection by soluble annexin V and/or PS vesicles.
....................
Annexin II Is Associated with Entry/Fusion of HIV-1 in Macrophages.
Next, we focused on when in the virus life cycle annexin II cooperates with HIV-1 to promote infection. Consistent with SLPI (2, 3), blockade of annexin II on macrophages did not significantly interrupt HIV-1 binding to the cells (Fig. 5 C), likely dissociating it from a direct interaction with CD4 and/or CCR5. In confirmatory studies, anti–annexin II was incorporated into a fusion assay in which effector cells expressing recombinant Env, but lacking viral PS, were cocultured with target cells expressing recombinant CD4 and coreceptors (23). In the absence of PS, anti–annexin II was ineffective in interrupting this fusion process (not depicted), ruling out a specific interaction with Env, CD4, and/or coreceptors. These data emphasize the potential unique constraints of macrophage–HIV-1 entry events that might be optimized through an annexin II–PS cofactor linkage. Although the role of annexin II in viral entry may involve participation in internalization or structural/functional facilitation of fusion events, it was unclear whether membrane annexin II had intracellular access. Because apoptotic cells also bind through PS to annexin II on macrophages (24, 25), we exposed macrophages to apoptotic Jurkat cells (PS+) as a model of annexin II–dependent internalization. By immunofluorescence, annexin II could be found within the early phagosome membrane, consistent with surface membrane internalization (Fig. 5 D). Whether internalization is essential to viral entry is under investigation, but by multiple criteria, the role of annexin II appears instrumental early in the infection process. To confirm that disconnecting the HIV–annexin II bond inhibits the virus life cycle after HIV-1 binding but before reverse transcription, as shown for SLPI (3), macrophages were infected with or without annexin II inhibitors and the formation of nascent viral DNA was assessed using a nested PCR-based assay. The presence of anti–annexin II during the initial virus inoculation period dramatically inhibited subsequent viral DNA synthesis, as demonstrated by the HIV-1–specific 730-bp PCR product (Fig. 5 E), even though annexin II blockade did not disengage the viral-binding step (Fig. 5 C). Collectively, these data indicate that interference with macrophage membrane annexin II inhibits infectivity after binding, but pre-reverse transcription, consistent with a stranglehold on the viral entry/fusion step.
......................
DISCUSSION
In this study, we identify annexin II as a novel macrophage membrane–binding protein for the innate host defense protein, SLPI, by multiple parameters including immunoprecipitation, mass spectrometry, peptide sequencing, and binding specificity. Striking was the ability of inhibitors of annexin II to mimic the kinetics and apparent mechanism of HIV-1 suppression by SLPI, denoting a shared site of action. Although not ruling out additional binding targets for SLPI, annexin II appears to be significant in mediating its anti–HIV-1 activity. Subsequent to binding of HIV-1 to the canonical receptors, CD4 and CCR5, HIV-1 fuses with the host cell membrane that might be facilitated by viral envelope PS (14). PS is not encoded by HIV-1, but rather is acquired from its host cell membrane as it exits the cells (26). During viral assembly at the cell surface or within cytoplasmic vesicles, cell membrane components become incorporated into the new viral coat along with virally encoded gp120/gp41. The resulting mosaic HIV-1 envelope represents a lipid bilayer with a unique cholesterol/phospholipid composition, embracing viral and host molecules, including PS. Although PS enhances infection, it does not mediate initial binding of the virus to the target cells (14), consistent with our observations that neither soluble annexin II, RNAi, anti–annexin II, nor the annexin II ligand, SLPI, blocks HIV-1 binding, but rather inhibit postbinding and pre-reverse transcription, a point in the viral life cycle consistent with a proposed role for annexin II as a cellular fusogenic cofactor.
Annexin II reportedly is found in caveolae and lipid rafts in association with cholesterol (27) and mediates interactions between cholesterol-rich membrane domains and the actin cytoskeleton (28, 29), which may navigate HIV-1 through the labyrinth of the cell membrane. Our data favor a model in which PS in the viral coat interacts with annexin II on the surface of macrophages subsequent to recognition-specific gp120 interactions with CD4 and the chemokine coreceptors that instigate coiled coil exposure of gp41 fusion domains to interact with the lipid bilayer of the target cell (10, 30), and then engage an annexin II–dependent fusion/entry pathway leading to productive infection.
Annexin II may represent a molecular pathway exploited by HIV-1 unique to macrophage hosts and thus, a potential target to block their virus susceptibility. Both laboratory-adapted and clinical M tropic isolates appear to coopt this host cell bridge into the cell's interior. Whether annexin II selectively boosts the viral entry/fusion process or possibly also influences pathways involved in HIV-1–mediated macrophage signaling, viral DNA transport, or subsequent virion construction, budding and release remains to be deciphered. Annexin II has the potential to traverse into intracellular compartments and interaction of annexin II with the actin cytoskeleton may not only facilitate internalization, but also the trafficking of HIV-1 within the cell and/or represent the scaffolding for viral transcription (30). Nonetheless, our data support a dominant role of annexin II to be in the early steps of the infection process, preceding reverse transcription. Annexin II may represent one of multiple potential cofactors, such as syndecan and human neutrophil elastase (31, 32), which independently or collaboratively might be usurped by HIV-1 to facilitate the infectious process. Because annexin II is a membrane-associated protein, best known as a docking station for tissue plasminogen activator/plasminogen (16), it is unclear if it transduces a signal because it lacks a hydrophobic signal sequence, but conceivably, may serve as an adaptor in a signaling cascade. Annexin II can be phosphorylated at key residues by several kinases, including the src oncogene (17) and Pyk-2 (15), a tyrosine kinase activated by HIV-1 (33, 34), but such a pathway awaits delineation. Although less persuasive due to the temporal association of SLPI/anti–annexin II inhibition with preintegration events, SLPI may also influence NF-{kappa}B activation and/or proteasome inhibition (6, 8), both of which are requisite in an optimal infection process (35–37).
Whether the relative lack of abundance of annexin II on the perimeter of immature blood monocytes compared with mature macrophages influences their differential permissiveness to HIV-1 infection is of interest. A related, intriguing question is whether the viral tropism characteristic of T cell and macrophage targets bears any association with their divergent annexin II expression. Annexin II on macrophages may preferentially facilitate entry of virions expressing PS acquired during exit from prior macrophage hosts or from T cells undergoing apoptosis that only then express PS on their outer membrane leaflet (38, 39), as compared with virions budded from PS-less viable T cells. R5 viruses mediate both mucosal and blood-borne transmission of HIV-1 infection, whereas the X4 (T tropic) viruses typically abound in the later stages of disease during clinical progression to AIDS (11, 40, 41). Moreover, when infected T cells succumb to apoptosis, recognition of their newly exposed PS will promote clearance by annexin II–bearing macrophages with the potential for HIV-1 transfer (42). It is conceivable that PS–annexin II interactions in the cytoplasmic vesicles and late endosomes of macrophages, where structural assembly of virions occurs (12, 43) and annexin II is found (28), not only serve as a construction scaffolding, but also as a tether to retain virions intracellularly in a covert maneuver to avoid detection at the cell surface. Because the S100A10 component of the annexin II complex has been shown to facilitate arbovirus exocytosis (44), such a role in HIV-1 egress might also be considered. Annexin II/PS may also contribute to the host cell–derived cloak of the hypothetical Trojan exosomes that subversively deliver retroviral particles to nearby cells (45), thus a co-conspirator with HIV-1 both going in and coming out.
The identification of a novel role for annexin II as a cellular cofactor in HIV-1 entry/fusion has implications for specific antiviral strategies, albeit primarily targeting macrophage infection. Nonetheless, as macrophages may contribute to initial viral selection, dissemination, and transmission of virus to CD4+ T cells, and serve as long-term covert reservoirs of HIV-1 (11, 40, 46), this would be an enviable goal. Particularly evident is the enormous viral burden in macrophages in later stage HIV-1/AIDS during opportunistic infections (12, 21, 22). Further unraveling of the complex interplay between viral envelope and macrophage membrane constituents remains crucial to the development of antiviral agents active before permanent viral integration into the host cell genome when the virus is most vulnerable. The persistence of HIV-1 infection, coupled with its incredible mutation rate and insular reservoirs, focuses attention on host cell constituents usurped by the virus as potential intervention targets. In this regard, annexin II, a host cell molecule that the virus has appropriated for easing its entrance into the host cell, represents a likely candidate, and SLPI, an endogenous ligand for annexin II, or other annexin II–specific blockades, may represent a therapeutic impediment to the infection process. Clearly, viral pathogens other than HIV-1, including CMV and respiratory syncytial virus (19, 20), also take advantage of target cell annexin II to enhance their infectivity and/or dissemination, and furthermore, bacteria trigger annexin II recruitment to their attachment sites (27), all suggesting its broader involvement in microbial entrance and pathogenesis.
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j
jake,
VX950 is a HCV protease inhibitor, for a specific HCV protease.
VX950 therapy exhibited scary runaway mutations, (strains with a protease that were resistant to VX950), when it was used as monotherapy in early trials.
VX950 will NEVER be used as monotherapy.
VX950 will need an immune modulator's help.
(or a cocktail of antivirals like today's current HIV therapy, which is a long way off if ever).
Right now that immune modulator is interferon.
Bavituximab is an ab that targets a host-cell-derived molecule that is externalized on all enveloped viruses.
A second mechanism of Bavi involves the fact that the exact target of bavi just so happens to be the molecule that provides the "fork in the road" which diverts your immune system from dealing appropriately with a virus.
Another fascinating (and cutting edge/recent insight) is that Bavituximab also may clean up the debris that came about because the virus wasn't noticed correctly in the first place, - debris that circulates through the body and dampens the immune response further.
Interferon is Bavi's potential competition.
Bavi in early trials has already been shown to meet or beat interferon's effect in similar patient pools with similar regimens.
(with no toxicity)
IMO, the more good antivirals like VX950 the better. I hope there are several that eventually make it.
Schering, Vertex, VRUS, etc...
Bavi needs to keep performing as it has been.
I also expect, obviously, that eight weeks of bavi will show better results than two weeks...
I wonder how much of an "adaptive immune" response we'll see in the 8 wk study...
(It's my opinion that parameters of the 8 wk HCV/HIV trial were influenced/guided by insights gained from research at Duke.)
j
goat, OT, re: "Big 3" vaccine
Bart Haynes, Director of Duke's Human Vaccine Institute, (among other things), is working on a vaccine for the "big 3", along with Norm Letvin and others, via govt funds.
I wonder how it's going.
http://humanvaccine.duke.edu/modules/develop/index.php?id=3
"Over the past two years, DHVI investigators have expanded their expertise in Mycobacterium tuberculosis (MTB) and Plasmodium falciparium (malaria) research. Working with the support of a grant from the National Institutes of Health, our investigators have teamed with Dr. William Jacobs at Albert Einstein College of Medicine, Dr. Louis Miller of the NIH, and Dr. Norman Letvin of Harvard, to form an inter-institutional, interdisciplinary effort to develop an HIV, TB and malaria trivalent vaccine for children.
A major hurdle in the development of a successful TB vaccine for adults is being addressed through this DHVI program. Adults have pre-existing immune responses to environmental mycobacteria, which interfere with the immune responses and the protection generated by the current TB vaccine, BCG. These pre-existing responses may interfere with novel TB vaccine candidates. Dr. Richard Frothingham and coworkers have developed a murine model of latent M. avium infection that mimics many aspects of latent human infection with environmental mycobacteria. His lab is using this model to characterize the CD4 and CD8 components of immune responses to environmental mycobacteria that interfere with protective responses to TB vaccines, and to evaluate several proposed mechanisms for this interference. The ultimate goal is the development of TB vaccines which are effective in adults. This work is relevant to the development of vaccines against other bacteria, including Bacillus anthracis and Yersinia pestis."
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j
Must Read - brand new -
http://www.nature.com/bjc/journal/vaop/ncurrent/abs/6604059a.html
blocking PS in autologous tumor vaccines confers tumor-specific immunity
j
--------------
British Journal of Cancer advance online publication 30 October 2007; doi:10.1038/sj.bjc.6604059 www.bjcancer.com
Photodynamic therapy-generated vaccines: relevance of tumour cell death expression
M Korbelik1, B Stott1 and J Sun1
1Department of Cancer Imaging, British Columbia Cancer Agency, Vancouver, British Columbia, Canada
Correspondence to: Dr M Korbelik, Department of Cancer Imaging, British Columbia Cancer Research Centre, 675 West 10th Avenue, Vancouver, British Columbia V5Z 1L3,
Received 30 May 2007; revised 27 September 2007; accepted 27 September 2007; published online 30 October 2007
Recent investigations have established that tumour cells treated in vitro by photodynamic therapy (PDT) can be used for generating potent vaccines against cancers of the same origin. In the present study, cancer vaccines were prepared by treating mouse SCCVII squamous cell carcinoma cells with photosensitiser chlorin e6-based PDT and used against poorly immunogenic SCCVII tumours growing in syngeneic immunocompetent mice. The vaccine potency increased when cells were post-incubated in culture after PDT treatment for 16 h before they were injected into tumour-bearing mice. Interfering with surface expression of phosphatidylserine (annexin V treatment) and apoptosis (caspase inhibitor treatment) demonstrated that this post-incubation effect is affiliated with the expression of changes associated with vaccine cell death. The cured mice acquired resistance to re-challenge with the same tumour, while the engagement of cytotoxic T lymphocytes was demonstrated by detection of high numbers of degranulating CD8+ cells in vaccinated tumours. The vaccines prepared from ex vivo PDT-treated SCCVII tumour tissue were also highly effective, implying that surgically removed tumour tissue can be directly used for PDT vaccines. This opens attractive prospects for employing PDT vaccines tailored for individual patients targeting specific antigens of the patient's tumour.
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j
GNBT
GNBT has a mkt cap. under 200M,
110M shares outstanding,
Revenue of 180K
total debt 3M
35M in cash.
% held by institutions 2%
Only a couple analysts covering GNBT,
One of them happens to be Navdeep Jaikaria of Rodman & Renshaw....
j
Nina Bhardwaj, Persephone Borrow -
Keep an eye on their work.
Bhardwaj wrote the informative PS / PS receptor "Tethering and Tickling" review,
http://www.jcb.org/cgi/content/full/155/4/501
- She recently joined Haynes' CHAVI "Innate Discovery Team"
http://www.chavi.org/wysiwyg/downloads/CHAVI_Newsletter_1_4.pdf
- She's now with CHAVI studying changes in dendritic cells during Acute HIV Infection.
(I wonder what she'll find).
and Borrow-
Persephone Borrow
Program Leader of Discovery Team in Innate Immunity
Dr Persephone Borrow, PhD is a Senior Fellow at the University of Oxford and heads a research group within the Edward Jenner Institute for Vaccine Research. Dr Borrow received her PhD degree from the University of Cambridge in 1989. Her research career has focused primarily on innate and T cell responses in virus infections, which she has studied both in murine models and in humans. In the HIV field, her work has concentrated on the immune response in acute and early infection. She showed in 1994 that induction of virus-specific CD8+ CTL responses was associated with containment of primary viraemia. She subsequently demonstrated the impact that the early CD8+ T cell response has on control of virus replication and documented the ability of the virus to undergo rapid escape from epitope-specific CD8+ T cells. Dr Borrow’s current research interests include the definition of immune correlates of good control of early HIV replication, and analysis of the interplay between innate and adaptive responses in primary HIV infection.
I'm looking forward to Bhardwaj's and Borrow's paper due out soon titled
"Innate immune responses in primary HIV-1 infection."
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j
"OT": "Cationic Chemo"... Very interesting...
J Antimicrob Chemother. 2007 Oct 26
Stearylamine-bearing cationic liposomes kill Leishmania parasites through surface exposed negatively charged phosphatidylserine.
Banerjee A, Roychoudhury J, Ali N.
Infectious Diseases and Immunology Division, Indian Institute of Chemical Biology, 4, Raja S. C. Mullick Road, Kolkata 700032, India.
Objectives Lipid-associated formulations of antileishmanial agents have proved to be more effective therapies with reduced toxicities. Previous studies from our group and others revealed that liposomes bearing phosphatidylcholine and stearylamine (SA) themselves kill Leishmania and other protozoan parasites in vitro and in vivo, without causing any adverse effect on host. In the present study, we offer detailed insights into the mechanism of action of these liposomes. Methods Mechanism study was carried out using fluorometric, confocal and electron microscopic methods. Results Herein, we provide evidence for induction of membrane disruption by specific interaction with surface phosphatidylserine (PS) of Leishmania promastigotes and amastigotes, phospholipids normally not found on mammalian cell surface, with SA-containing liposomes. Cell surface PS on different forms of Leishmania facilitated liposome-induced parasite killing. The target selectivity of the liposomes was further proved through inhibition of antileishmanial activity with annexinV, and strong affinity with anionic PS rather than phosphatidic acid-containing liposomes for leishmanicidal activity. Conclusions SA-bearing liposomes specifically kill Leishmania, but are non-toxic to murine peritoneal macrophages and human erythrocytes.
http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=17965031&ordinalpos=1&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum
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j
then again....
* In the SINGLE DOSE study, (in former non responders to immunotherapy), half the patients in the 1 mg/kg cohort, and also half the patients in the 3 mg/kg cohort, achieved a half log decrease.
and that was just one single dose of bavi, in former non responders to immunotherapy...
* There was also a patient who got 3 mg and did a 1.5 log decrease.
and again- that was just one single dose of bavi, in former non responders to immunotherapy...
* then, 5 out of 6 patients at the 6 mg dose did a half log, or better
and again- that was just one single dose of bavi, in former non responders to immunotherapy...
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In the multi-dose study, (and it was only four doses over 2 weeks), half the patients at 3 mg did 1 log.
Maybe less bavi, more doses, over a longer period, will achieve good viral reduction.
PPHM seems to think that once a week for a longer time period is promising.
and I can only assume that they feel this way based on Duke research INTO THE IMMUNE MODULATING MOA.
Maybe a 0.3 mg/kg dose will have impressive results after 8 weekly infusions.
Maybe the optimal dose will still be around 3.0
j
steve,
By the Dec. CC they will be through the 1st cohort, and I assume will be well into the 2nd, (possibly starting the 3rd) - depends on how long they have to progress through a dose level/cohort before starting the next one...
Perhaps we'll simply hear something general saying it was safe in patients treated to date, (it is a safety trial after all), and they've added a new site, etc.
Perhaps they'll mention in general that it's showing signs of efficacy.
Perhaps they'll mention some specific numbers, but remember this is a dose escalation trial, and we don't know the dose levels per cohort. Hopefully (probably) they'll be starting at 0.3 and what do you expect from that dose? - safe.
Who knows. We'll see.
j
steve,
SK, during the Sept CC,
"we have been working with add’l sites who would like to participate in the [HCV/HIV] trial, and expect to bring those sites online in the near future. We also intend to conduct add’l HCV studies to evaluate new Bavi treatment schedules and to explore its use in combination with existing therapies. Data, even partial data, we will gather from the HCV-HIV study, with its extended treatment duration s/b invaluable in designing these next HCV studies. Both we and our advisors are very pleased with the results generated to-date from the HCV pgm. The potential importance of this pgm was highlighted by the distinction of being selected for an oral presentation at the AASLD Meeting in Nov., one of the most prestigious liver disease meetings in the world.
Our collab. with HIV researchers at Duke remains strong and is making good progress. The collab. is providing exciting, new insights into the potential of Bavi, and other Anti-PS antibodies, in HIV – data which otherwise would be extremely difficult, if not impossible, to generate. We look fwd to reporting on these results at a time our collab’s feel appropriate.
In addition, we recently reported that we are negotiating with the DTRA for a contract which could total over $44mm over the next 5 yrs., to study the potential of Bavi and and other Anti-PS antibodies for the treatment of hemorrhagic fever virus infections [ex: Lassa, Marburg, Ebola]. Negotiations are active, and we remain excited about this unique opportunity to study new uses for the Anti-PS technology, while at the same time helping support our current dev. pgms.
So, what dev’s do we anticipate for the Bavi AV pgm between now and the next CC in Dec.?
• Adding New Clinical Sites to the HCV-HIC Co-Infection Trial
• Significant Progress in the HCV-HIV Trial, Allowing Periodic Updates
• Presenting Final Data from Ph.1 Repeat-Dose HCV Study at AASDL in Nov.
• Completing Contract Negotiations with the DTRA"
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j
Steve King: HCV statements from Bio Investors presentation -
"Our Bavituximab HCV program addresses a large market, with over 3 billion in worldwide sales associated with HCV infection in 2006. Immunotherapeutics represent approximately 70% of the market, and Bavituximab falls generally under the immunotherapy class of drugs for HCV infection."
"Binds to PS in this case exposed on virus and virally infected cells. It binds to all enveloped viruses we've tested to date, including HCV, HIV, influenza, and CMV. It has a unique mechanism of action, again - the ability to directly destroy the infected cells, and also to again- switch on the immune system to recognize the virus infection and to have the immune system fight the virus itself.
Potentially a nonmutatable target, the target is not made by the virus, but rather is a host component.
For the HCV program we've completed two clinical studies in HCV infected patients, a single dose monotherapy study, and a repeat dose monotherapy study. In both cases the drug appeared safe and well-tolerated. In addition we did see some encouraging signs of antiviral activity, highlighted in the repeat-dose study by the fact that half of the patients at the 3mg/kg dose level had about an average of a one log or a 90% peak reduction in viral load which is pretty consistent with immunostimulatory molecules in this patient population."
Based on these results we've now initiated a new phase 1 study. This is another HCV study in which the HCV patients are also coinfected with HIV. There are a few primary goals and reasons for this patient population. The primary goal of the study is to study a now more extended dosing regimen. So in the prior repeat dose study, we treated four times over two weeks, now we're giving eight weekly doses, again, with the idea being that - if you're stimulating an immune response to the virus, you want to boost that, and if you're going to boost the response you want to do that over a more extended period of time.
In addition we know that both the HCV and HIV viruses and virally infected cells have our target on them, so we have the potential to impact both of those viral loads. It's something we do want to understand because HIV infected patients are a significant portion of the HCV patient population.
So this gives us the ability to look at a patient population that's typically not involved in HCV trials, and determine - should we be eliminating those patients from our trials, or is it a patient population we can potentially treat."
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j
correct steve,
Bavi's competition in the HCV space is the common/fundamental ingredient of HCV SOC therapy- interferon, and if bavi remains successful/safe it would be paired with ribavirin, and hopefully the newer antivirals if they remain successful/safe.
(and that's been the plan all along).
Steve King even, for the first time, recently compared Bavi's HCV efficacy to interferon, at the Bio Investors Conf. presentation.
Did any of you catch the comment??.....
SK: "For the HCV program we've completed two clinical studies in HCV infected patients, a single dose monotherapy study, and a repeat dose monotherapy study. In both cases the drug appeared safe and well-tolerated. In addition we did see some encouraging signs of antiviral activity, highlighted in the repeat-dose study by the fact that half of the patients at the 3mg/kg dose level had about an average of a one log or a 90% peak reduction in viral load which is pretty consistent with immunostimulatory molecules in this patient population."
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It's looking to me as if they're liking the 'once a week' Bavi regimen, since it was used in the very impressive Indian cancer 1B trial, and will be used in the phase 2 cancer trials, and the same 'once a week' is also the bavi schedule for the HCV/HIV trial.
I'm looking forward to seeing what 8 weeks of Bavi monotherapy once a week can do in the HCV/HIV patients, some of which are naive to immunotherapy.
I agree with Brandon that if we see greater than one log it's goooood news, as we'll clearly have a contender for replacing interferon, with equal or better efficacy, with huge advantages in the safety/tolerability profile.
j
terry,
Bavi is a protein.
C6446 H9946 N1702 O2042 S42
j
serene,
'government has interest in viral bavituximab, thus its monetary potential is not so barren as all that.'
I think that qualifies as the understatement of the week :)
So far the DoD has funded:
bavi against prostate cancer,
bavi against breast cancer,
and bavi as a tumor imaging agent.
I expect the DoD (via DTRA's TMTI program) to fund bavi against HFV's, with the largest grant yet.
When Duke's / CHAVI's / Gates CAVD's Barton Haynes' research into how exposed PS is the reason that the immune system fails early against HIV,
- and that poster info (from the recent Gates HIV vaccine conf.) is first out of over two hundred posters, but has yet to show up in any of Haynes published papers,
-and Haynes' other poster from the conf., (listed fifth) has already been published as a paper recently, (which also had to do with phospholipid binding of nabs),
I'd expect him to publish a paper on their work into exposed PS from apoptotic cells and the microparticles shed from those cells as the critically important link responsible for the success of the virus during acute HIV infection.
They're already on record several times mentioning this topic -
from January in the CHAVI admin meeting,
from March on Haynes CAVD Mision and Goals page,
from April's CHAVI 012 clinical study,
and now from Sept at the Gates Seattle event.
There is a growing consensus in the research community that shed membrane micro-particles play a much larger immunosuppressive role than previously thought in both cancer and HIV pathogenesis, and it's looking like an important mechanism of action of Bavituximab is in binding those PS-exposing micro-particles, thus clearing out the literally overwhelming apoptotic debris that has been down-regulating the immune response to HIV and cancer.
j
atherosclerotic plaque -
Must read the discussion section of this paper -
Shed Membrane Microparticles With Procoagulant Potential in Human Atherosclerotic Plaques
A Role for Apoptosis in Plaque Thrombogenicity
http://circ.ahajournals.org/cgi/content/full/99/3/348
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Discussion
Apoptosis is a common event that occurs in atherosclerosis.1 2 3 4 5 6 7 However, no direct evidence has been provided for a beneficial or a harmful role for this process in plaque development and progression. In this study, we examined the role of in situ apoptotic cell death in the promotion of plaque thrombogenicity.
TF is a key element in the initiation of the coagulation cascade. In the normal vessel, TF expression is restricted to the adventitia17 and contributes to vessel repair after vessel injury. Enhanced TF expression and activity have been reported in human atherosclerotic plaques,16 17 18 19 20 21 22 and it is now believed that the increase of TF activity is a major determinant of plaque thrombogenicity. However, TF activity is highly dependent on the presence of phosphatidylserine,24 25 26 27 and it has recently been shown that apoptotic cell death results in phosphatidylserine exposure on the cell surface conferring a potent procoagulant activity to the cell.9 10 11 12 13 14 Therefore, we hypothesized that plaque thrombogenicity may be greatly influenced by the occurrence of apoptotic cell death.
We detected substantial expression of TF in TUNEL-positive areas of plaques. Although the TUNEL method, in some instances, may reveal processes other than apoptosis,30 we have adapted the technique to enhance its specificity for the detection of apoptosis. In addition, we have previously shown6 that in the human atherosclerotic plaque, TUNEL-positive cells colocalize with caspase 3, which is characteristic of apoptosis.33
Extracellular expression of TF in the apoptotic areas suggested to us that it was probably released in microparticles during cell death. The finding of a close association between TF expression and apoptosis in acellular and cellular regions of atherosclerotic plaques suggested the possibility of synergy between TF and apoptotic cell membranes, rendering them highly thrombogenic.
To confirm this hypothesis, we searched for the presence of shed membrane particles with procoagulant potential in atherosclerotic plaques. In this study, we show that a large proportion of phosphatidylserine-bearing microparticles is produced in the atherosclerotic plaque. A number of arguments indicate that these microparticles most likely originated from apoptotic cells: (1) Several groups have shown that apoptosis occurs in the atherosclerotic plaque and may contribute to the development of the acellular lipid core.1 2 3 4 5 6 7 30 (2) Stimuli, like pro-inflammatory cytokines, that lead to cell death in the atherosclerotic plaque are potent inducers of apoptosis,34 and TUNEL-positive labeling in the plaque is highly associated with caspase expression,3 6 leading to the suggestion that necrosis in the plaque is a late secondary process due, in part, to the accumulation of unremoved apoptotic bodies. (3) We have previously shown29 that phosphatidylserine-bearing microparticles stem from surface blebs of apoptotic cells and their amount is correlated to the extent of apoptosis. (4) Phosphatidylserine exposure on the external layer of the cell membrane and shedding of membrane microparticles are early events of apoptosis and are produced even when secondary necrosis does not occur.
Interestingly, we found that these plaque-derived apoptotic microparticles account for almost all the TF activity of the plaque extracts, indicating a direct causal relationship between their presence and TF activity. This suggests that shed membrane apoptotic microparticles may play a major role in the initiation of the coagulation cascade. On the other hand, most of these microparticles originated from macrophages and lymphocytes that are known to be abundant at sites of plaque rupture.35 36 37 We therefore propose that apoptotic death of a proportion of these cells may greatly enhance the thrombus formation accelerating vessel occlusion and could lead to acute infarction.
In addition to their direct effect in promotion and amplification of the coagulation cascade, the apoptotic particles bearing CD11a may also act in a variety of intercellular adhesion processes and may be responsible for dissemination of the procoagulant potential to sites remote from the microenvironment of their formation.14 They may also provide the substrate for secretory phospholipase A2, leading to the generation of lysophosphatidic acid, a potent mediator of the inflammatory reaction and a potent platelet agonist.38 Furthermore, such microparticles may play an important role in transcellular lipid metabolism by their concentrated delivery of bioactive lipids.39
Once plaque material is exposed to circulating blood after plaque rupture or erosion, vascular thrombosis may ensue and may culminate in vascular occlusion, precipitating acute ischemic syndromes.40 Procoagulant potential of the exposed material is therefore a key determinant of plaque thrombogenicity and hence of the extent of vascular thrombosis and luminal narrowing. Our results provide strong evidence that apoptotic cell death in the atherosclerotic plaque is a major determinant of plaque thrombogenicity and could offer novel therapeutic strategies for preventing thrombus formation on plaque rupture.
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j
more beautiful Bavi / Cisplatin synergy -
Bavi not only seems to add no toxicity to chemo as stated by PPHM,
Bavi also could/should make chemo safer / improve Cisplatin's safety profile
J Thromb Haemost. 2007 Oct 8
Chemotherapy-induced thrombin generation via procoagulant endothelial microparticles is independent of tissue factor activity.
Lechner D, Kollars M, Gleiss A, Kyrle PA, Weltermann A.
Department of Medicine I, Medical University of Vienna, Vienna, Austria.
Background: Cisplatin-based chemotherapy predisposes cancer patients to thromboembolic events.
Objectives: In this study, we investigated whether endothelial damage, via formation of procoagulant endothelial microparticles (EMP), contributes to cisplatin-related hypercoagulability. Methods: Cell viability and caspase-3/7 activities were assessed in two EC lines (HUVEC, HMVEC-L) after exposure to cisplatin (1, 2.5, 5, 10, and 20 muM) for up to 120 h. Counts and procoagulant activity of EMP were measured by flow cytometry and a thrombin generation assay, respectively. Tissue factor (TF) antigen and TF-dependent procoagulant activity of EMP were determined by ELISA and a novel functional assay. Results: By inducing apoptosis, cisplatin dose-and time-dependently decreased viability of confluent HUVEC and HMVEC-L endothelial cells. Progression of endothelial cell death was accompanied by an increased release of EMP (relative increase at 20 muM cisplatin for 48 h versus control: HUVEC 6.5-fold, p < 0.001; HMVEC-L 18.4-fold, p < 0.001). EMP were highly procoagulant (relative increase at 20 muM cisplatin for 48 h versus control: HUVEC 2.5-fold, p < 0.001; HMVEC-L 5.9-fold, p < 0.001). EMP-driven thrombin generation, however, was not dependent on TF: TF expression and TF procoagulant activity levels on microparticles were only marginal and EMP-associated thrombin generation remained unchanged when the extrinsic pathway was blocked by omission of factor VIIa and/or incubation with an anti-human TF-antibody. In contrast, blocking of phospholipids by annexin V markedly diminished EMP-associated procoagulant activity. Conclusions:In vitro, cisplatin induced the release of EMP which showed TF-independent procoagulant activity.
http://www.ncbi.nlm.nih.gov/sites/entrez?Db=pubmed&Cmd=ShowDetailView&TermToSearch=17922809&ordinalpos=2&itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum
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j
PPHM short % of float is 2%.
j
continue to enter?
Actually shorts are basically unchanged since last month, and have declined the previous 4 months.
October Mid Month 2007 4,458,667 0.66
September End Month 2007 4,429,317 (2.06)
September Mid Month 2007 4,522,468 (6.14)
August Mid Month 2007 4,818,099 (1.68)
July Mid Month 2007 4,900,510 (71.17)
j
shorts-
October Mid Month 2007 4,458,667 up 0.66%
j
TB infected cells: exposed PS -
Survival of Mycobacterium tuberculosis in Host Macrophages Involves Resistance to Apoptosis Dependent upon Induction of Antiapoptotic Bcl-2 Family Member Mcl-11
The Journal of Immunology
http://www.jimmunol.org/cgi/content/full/170/1/430
Introduction
Mycobacterium tuberculosis, the causative agent of pulmonary tuberculosis, infects one-third of the world’s population (1). It accounts for more deaths each year than any other single infectious bacteria (2). Its ability to survive and replicate in the host macrophage is critical to its pathogenesis, emphasizing a need for a clearer understanding of its interactions with the host macrophage. In vitro experimental models have demonstrated that M. tuberculosis infection causes apoptosis of host macrophages. This has been demonstrated by the detection of annexin V binding to surface-exposed phosphatidylserine early after infection with M. tuberculosis (3). In vitro infection of human macrophages with M. tuberculosis strain H37Ra or strain H37Rv caused TNF-{alpha}-dependent apoptosis demonstrated by a genomic DNA ladder, nuclear fragmentation, and condensation as well as by TUNEL labeling (4). Keane et al. (5) demonstrated further that avirulent M. tuberculosis strains and Mycobacterium bovis bacillus Calmette-Guérin (BCG)4 cause more apoptosis than virulent strains, implicating a role for apoptosis in host defense against M. tuberculosis.
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Evolution has favored pathogenesis that resembles apoptosis.
j
Tuberculosis: exposed PI & PE
Identification of the surface-exposed lipids on the cell envelopes of Mycobacterium tuberculosis and other mycobacterial species.
http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=177678&blobtype=pdf
A Ortalo-Magné, A Lemassu, M A Lanéelle, F Bardou, G Silve, P Gounon, G Marchal, and M Daffé
Laboratoire de Pharmacologie et Toxicologie Fondamentales du Centre National de la Recherche Scientifique, Toulouse, France.
Abstract
The surface-exposed lipids of Mycobacterium tuberculosis, Mycobacterium avium, Mycobacterium kansasii, Mycobacterium gastri, Mycobacterium smegmatis, and Mycobacterium aurum were isolated by gentle mechanical treatment of cells with glass beads. Analysis of the exposed lipids demonstrated a selective location of classes of ubiquitous lipids on the surfaces of mycobacteria. While phosphatidylethanolamine and phosphatidylinositol mannosides were exposed in all the species examined, dimycoloyl trehalose ("cord factor") was identified in the surface components of M. aurum only. Furthermore, monomycoloyl trehaloses and triacylglycerides were identified in the surface-exposed lipids of M. avium and M. smegmatis but not in those of the other mycobacterial species examined. The species- and type-species specific lipids were present on the mycobacterial cell surface: phenolic glycolipids, dimycocerosates of phthiocerols, and lipooligosaccharides were identified in the surface-exposed materials of M. tuberculosis (Canetti), M. kansasii, and M. gastri, whereas glycopeptidolipids were identified in the outermost lipid constituents of M. avium and M. smegmatis. This difference in the surface exposure of lipids of various mycobacterial species may reflect differences in their cell envelope organizations. Brief treatments of M. tuberculosis with Tween 80 prior to the use of glass beads led to erosion of regions of the capsule to expose gradually both cord factor and other lipids on the cell surface of the tubercle bacillus, demonstrating that the latter lipids are buried more deeply in the cell envelope and leading to the proposal of a scheme for the location of the capsular lipids of the tubercle bacillus.
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Evolution has favored pathogenesis that resembles apoptosis.
j
jake,
re: mabs -
mabs are antibodies. One of the important differentiators is the region of the ab that sticks to it's target, called the 'variable' region. Think of typical antibodies as having two feet that stick. Peregrine is the only company working with therapeutic abs that deliberately target phospholpids. PS and other phospholipids have traditionally been considered "off limits" targets, but recently the folks at MD Anderson, (Alan Schroit etc.), have made discoveries into important differences into what look to be safe abs to phospholipids, (and why). If Peregrine's anti-PS works, ( actually I suppose I should say 'if it keeps working'), PS will be a very important target, as PS is the reason that so many diseases and critters get the better of us. (That wasn't really known at the time Thorpe was designing his anti-PS. His work came about for a different reason - because of his discovery of PS becoming exposed on tumor vasculature, but the understanding that PS itself is immunosuppressive - that it alters our immune response in a very fundamental way, was/is new, and it carries implications for treating "disease" itself, in the broadest sense imaginable). Until recently, apoptotic cells were thought to be immunologically inert/neutral, but they're not, they're actively anti-inflammatory. Our immune system recognizes PS as a universal symptom of dying native cells, and reacts accordingly - by clearing it up, but with a 'kinder/gentler' pro-growth response, and diseases- cancer, viruses, malaria, tuberculosis, etc, etc,..., exploit this aspect of our immune response.
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Evolution has favored pathogenesis that resembles apoptosis.
j
bavi antibacterial -
"MRSA is a bacteria, not a virus."
Bacteria wear exposed PA, an anionic phospholipid.
Bavi binds PA.
Thorpe/Ran:
[0820] Most bacteria express the anionic phospholipid, PA. Antibodies that bind to PA, optionally with binding to other anionic phospholipids, can therefore be used as anti-bacterial agents. Although the antibodies of the invention can be prepared in E. Coli, and are thus not bacteriocidal in all circumstances, an anti-bacterial role in vivo is believed to result from the ability to fix complement. An intact antibody rather than an antibody fragment should therefore be used as an anti-bacterial agent. The 3G4 (ATCC 4545) and like antibodies are preferred for use in such embodiments, although any antibody that fixes complement and binds to PA may be employed, such as other PA-binding antibodies from Table 4.
http://appft1.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetahtml%2FPTO%2Fsearch-adv.html&r=5&p=1&f=G&l=50&d=PG01&S1=%28%22thorpe+philip%22.IN.%29&OS=in/%22thorpe+philip%22&RS=IN/%22thorpe+philip%22
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j
Also, the newset CHAVI clinical study, # 012, is slated to study
"immune cell activity after massive apoptosis during AHI"
they, (Haynes etc.), state that
"The nature of the innate response in AHI and its interaction with the adaptive response
may be among the factors involved in determining the set point of plasma viremia"
and
"A key implication of this hypothesis is the suggestion that innate responses may be harnessed to form an
important component of vaccine-elicited protective immunity, a setting in which
rapid triggering of effector functions following exposure to HIV or HIV-infected
cells is likely to be critical."
so in CHAVI 012,
"It is proposed to characterize the
innate effector mechanisms activated in primary HIV infection and explore their
role in control of early virus replication; and to address whether HIV impairs
aspects of innate immunity in AHI to promote its persistence. This will facilitate
the design of vaccination strategies to target key effector pathways and/or
circumvent infection-associated impairments in innate functions."
what are those ' key effector pathways' / 'infection-associated impairments in innate functions' ?
"Acutely expressed cytokines and apoptotic microparticles
hypothesized to play a key role in AHI pathogenesis will be
assayed.
The CHAVI panel of cytokines including alpha IFN, TNF alpha, IL10,
TGF-beta, as well as a Luminex panel of T and B regulatory cytokines, and
plasma microparticles will be quantitated."
http://72.14.209.104/search?q=cache:BCKueWKqWTIJ:www.chavi.org/wysiwyg/downloads/CHAVI_012_protocol_v1.pdf+%22CHAVI+012%22&hl=en&ct=clnk&cd=1&gl=us&client=firefox-a
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j