Increased interleukin-17 in the cerebrospinal fluid in sporadic Creutzfeldt-Jakob disease: a case-control study of rapidly progressive dementia

Background: Inflammatory responses in the cerebrospinal fluid (CSF) of patients with sporadic Creutzfeldt-Jakob disease (sCJD) remain elusive. Methods: We conducted a case-control study, in which 14 patients with sCJD, 14 with noninflammatory neurological disorders, and 14 with autoimmune encephalitis were enrolled. We used the suspension array system to measure the concentrations of 27 cytokines in CSF. The cytokine titers of the three groups were compared, and the correlation between the relevant cytokine titers and clinical parameters was investigated in the patients with sCJD. Results: Levels of the two cytokines interleukin (IL)-1 receptor antagonist and IL-17 were significantly elevated in the patients with sCJD compared with those in the patients with noninflammatory neurological disorders: IL-17 levels in sCJD were approximately ten times higher than in the noninflammatory neurological disorders (mean, 35.46 vs. 3.45 pg/ml; P < 0.001) but comparable to that in encephalitis (mean, 32.16 pg/ml). In contrast, levels of classical proinflammatory cytokines such as IL-12(p70) and tumor necrosis factor-a were increased only in encephalitis. Although not significant, IL-17 titers tended to be higher in the patients with shorter disease duration before CSF sampling (r = -0.452; P = 0.104) and in those with lower CSF total protein concentrations (r = -0.473; P = 0.086). Conclusions: IL-17 is significantly increased in CSF in sCJD, which can be an early event in the pathogenesis of sCJD.