Elevated cerebrospinal fluid YKL-40 levels in patients with anti-gamma-aminobutyric- acid-B receptor encephalitis

Objective: Anti-gamma-aminobutyric-acid-B receptor (GABAbR) encephalitis is a rare form of autoimmune encephalitis. Until now, there are few biomarkers that can indicate the severity and prognosis of patients with anti-GABAbR encephalitis. The objective of this study was to exam the changes of chitinase-3-like protein 1 (YKL-40) in patients with anti-GABAbR encephalitis. In addition, whether YKL-40 could indicate the disease severity was also evaluated.

Methods: The clinical features of 14 patients with anti-GABAbR encephalitis and 21 patients with anti-N-methyl-d-aspartate receptor (NMDAR) encephalitis were retrospectively studied. YKL-40 levels in serum and cerebral fluid (CSF) of patients were detected by enzyme-linked immunosorbent assay. The correlation of modified Rankin Scale (mRS) score of encephalitis patients and YKL40 levels were analyzed.

Results: YKL-40 levels in CSF were significantly higher in patients with anti-GABAbR encephalitis or anti-NMDAR encephalitis than those in controls. YKL-40 levels between these two encephalitis groups were not different. Moreover, YKL-40 levels in CSF from patients with anti-GABAbR encephalitis were positively correlated with the mRS score at admission and at 6-month follow-up.

Conclusion: YKL-40 level is elevated in CSF from patients with anti-GABAbR encephalitis at early disease stage. YKL-40 may be a potential biomarker indicating the prognosis of patients with anti-GABAbR encephalitis.