Curcumin ameliorates rat experimental autoimmune neuritis.

Experimental autoimmune neuritis (EAN) is a helper T cell-mediated autoimmune demyelinating inflammatory disease of the peripheral nervous system that serves as an animal model for human Guillain-Barre syndrome. Curcumin, a naturally occurring polyphenolic phytochemical isolated from the medicinal plant Curcuma longa, has anti-inflammatory activities. Here we investigated the therapeutic effects and potential mechanisms of curcumin in EAN rats. Exogenous curcumin treatment (100 mg/kg/day) significantly delayed the onset of EAN neurological signs, ameliorated EAN neurological severity, and reduced body weight loss of EAN rats. In EAN sciatic nerves, curcumin treatment suppressed the inflammatory cell accumulation and the expression of interferon (IFN)-γ, tumor necrosis factor-α, interleukin (IL)-1β, and IL-17. Furthermore, curcumin treatment significantly decreased the percentage of CD4(+) T helper cells in EAN spleen and suppressed concanavalin A-induced lymphocyte proliferation in vitro. In addition, curcumin altered helper T cell differentiation by decreasing IFN-γ(+) CD4(+) Th1 cells in EAN lymph node and spleen. In summary, our data demonstrate that curcumin could effectively suppress EAN by attenuating inflammation, indicating that curcumin might be a candidate for treatment of autoimmune neuropathies.