The neuroinflammatory biomarker YKL-40 for neurodegenerative diseases: advances in development. Baldacci F1,2,3,4, Lista S2,3,4, Palermo G1, Giorgi FS1, Vergallo A2,3,4, Hampel H2. Author information 1 a Department of Clinical and Experimental Medicine , University of Pisa , Pisa , Italy. 2 b Sorbonne University, GRC n° 21, Alzheimer Precision Medicine (APM), AP-HP, Pitié-Salpêtrière Hospital, Boulevard de l'hôpital , F-75013, Paris , France. 3 c Brain & Spine Institute (ICM), INSERM U 1127, CNRS UMR 7225, Boulevard de l'hôpital , F-75013, Paris , France. 4 d Institute of Memory and Alzheimer's Disease (IM2A), Department of Neurology, Pitié-Salpêtrière Hospital, AP-HP , Boulevard de l'hôpital , F-75013, Paris , France. Abstract Introduction: Neuroinflammation is a common pathophysiological mechanism in neurodegenerative diseases (ND). Cerebrospinal fluid (CSF) YKL-40 has recently been candidated as a neuroinflammatory biomarker of ND. Areas covered: We provide an update on the role of CSF YKL-40 as a pathophysiological biomarker of ND. YKL-40 may discriminate Alzheimer's disease (AD) from controls and may predict the progression from the early preclinical to the late dementia stage. In genetic AD, YKL-40 increases decades before the clinical onset. It does not seem a specific biomarker of a certain ND although sporadic Creutzfeldt-Jacob disease shows the highest YKL-40 concentrations. YKL-40 may discriminate between amyotrophic lateral sclerosis (ALS) and ALS-mimics. YKL-40 is potentially associated with the rate of ALS progression. YKL-40 correlates with biomarkers of neuronal injury, large axonal damage and synaptic disruption in various ND. It is not associated with the presence of the APOE-e4 allele whereas possibly linked to aging, female sex, Hispanic ethnicity and some genetic variants of the chitinase-3-like 1 locus. Expert opinion: There is growing evidence expanding the relevance of CSF YKL-40 as a pathophysiological biomarker for ND. Patients showing high YKL-40 levels might benefit from targeted clinical trials that use compounds acting against neuroinflammatory mechanisms, independently of the initial clinical diagnosis of ND.
