CHI3L1 and brain ischemia: Elevated serum YKL-40 levels have been shown in the carotid artery wall in patients with symptomatic (cerebral infarction, transitory cerebral ischemia or infarction of the optical artery) versus asymptomatic atherosclerotic plaques and the highest YKL-40 levels were localized to the lipid-rich core of the atherosclerotic plaque [34].