Lower serum interleukin‐22 and interleukin‐35 levels are associated with disease status in neuromyelitis optica spectrum disorders

AIMS: The exact pathogenesis of neuromyelitis optica spectrum disorder (NMOSD) remains unclear. A variety of cytokines are involved, but few studies have been performed to explore the novel roles of interleukin‐22 (IL‐22) and interleukin‐35 (IL‐35) in NMOSD. Therefore, this study was designed to investigate serum levels of IL‐22 and IL‐35, and their correlations with clinical and laboratory characteristics in NMOSD. METHODS: We performed a cross‐section study, 18 patients with acute NMOSD, 23 patients with remission NMOSD, and 36 healthy controls were consecutively enrolled. Serum levels of IL‐22 and IL‐35 were measured by enzyme‐linked immunosorbent assay (ELISA). The correlations between serum IL‐22 and IL‐35 levels and clinical and laboratory characteristics were evaluated by Spearman's rank or Pearson's correlation coefficient. RESULTS: The serum levels of IL‐22 and IL‐35 were significantly lower in patients with acute NMOSD and remission NMOSD than in healthy controls (IL‐22: 76.96 ± 13.62 pg/mL, 87.30 ± 12.79 pg/mL, and 94.02 ± 8.52 pg/mL, respectively, P < .0001; IL‐35: 45.52 ± 7.04 pg/mL, 57.07 ± 7.68 pg/mL, and 60.05 ± 20.181 pg/mL, respectively, P < .0001). Serum levels of IL‐35 were negatively correlated with EDSS scores and cerebrospinal fluid protein levels (r = −.5438, P = .0002 and r = −.3523, P = .0258, respectively) in all patients. CONCLUSIONS: Lower serum levels of IL‐22 and IL‐35 are associated with disease status in NMOSD. Additionally, lower serum levels of IL‐35 are associated with disease severity in NMOSD.