Th17 cells were recruited and accumulated in the cerebrospinal fluid and correlated with the poor prognosis of anti-NMDAR encephalitis.

Anti-N-methyl-D-aspartate-receptor (NMDAR) encephalitis is an autoimmune disorder characterized by memory deficits, psychiatric symptoms, and autonomic instability. The lack of suitable biomarkers targeting anti-NMDAR encephalitis makes the immunotherapy and prognosis challenging. In this study, we found that the Th17 cells were significantly accumulated in the cerebrospinal fluid (CSF) of anti-NMDAR encephalitis patients than that of control individuals. The concentration of the cytokines and chemokines including interleukin (IL)-1β, IL-17, IL-6, and CXCL-13 were significantly increased in the CSF of anti-NMDAR encephalitis patients. IL-6 and IL-17 were found to promote the differentiation of CD4+ T cells into Th17 lineage. The chemotaxis assay showed that CCL20 and CCL22 play essential roles in the migration of Th17 cells. Notably, the correlation between the expression of IL-17 and the outcome of anti-NMDAR encephalitis patients was analyzed. The data showed that high level of IL-17 was significantly correlated with the limited response to the treatment and relapse of anti-NMDAR encephalitis patients. Our results suggested the potential important involvement of IL-17 in anti-NMDAR encephalitis.