In cells and mice, the deletion of CHI3L1 alters the responses of glial inflammation, promotes microglial Aβ and astrocyte phagocytosis, and decreases amyloid plaque deposition, but glial activation and neuroinflammation may be dependent on context because the deletion of CHI3L1 could be neuro-protective in AD, but destructive in acute inflammation. Here, CHI3L1 is linked to Alzheimer disease.