Interleukin-17 in transverse myelitis and multiple sclerosis

CSF IL-6 is elevated in transverse myelitis (TM) and predicts disability. Since IL-17 regulates cytokines (TNFα, IL-1β and IL-6) known to stimulate IL-6 production by astrocytes, we sought to determine whether IL-17 was increased in TM and MS compared to healthy controls (HC) and other neurologic diseases (OND). IL-17 and IL-6 levels were measured in stimulated peripheral blood mononuclear cell (PBMC) supernatants from HC, MS, TM and OND. IL-17 was increased in TM compared to HC, MS, and OND (mean pg/ml ± standard error; HC: 36.1 ± 11.7, MS: 89.4 ± 23.3, TM: 302.6 ± 152.5, OND: 41.2 ± 13.0, p = 0.01). IL-6 was increased in TM relative to MS and HC (HC: 2624 pg/ml ± 641, MS: 6129 ± 982, TM: 12,536 ± 2657, OND: 6920 ± 1801, p < 0.002). MS patients with early disease (< 2 years) also had increased levels of IL-17 (p < 0.04) and IL-6 (p < 0.05). Cytokine neutralization experiments demonstrated that IL-6 was the main inducer of astrocyte IL-6 production. We conclude that IL-17 and IL-6 production from PBMC in TM and early MS are increased and induce astrocyte IL-6 production through IL-6.