Effects of polymethoxyflavonoids on T helper 17 cell differentiation in vitro and in vivo

We examined the effects of polymethoxyflavonoids (PMFs) on T helper (Th) 17 cell differentiation in vitro and in vivo. Five different PMFs including nobiletin (NOB), sudachitin (SUD), demethoxysudachitin, heptamethoxyflavone and natsudaidain were used for the in vitro study, and effects of those flavonoids on Th17 responses were investigated. NOB and heptamethoxyflavone significantly suppressed the proliferation response, but SUD, demethoxysudachitin and natsudaidain did not suppress the proliferation response. All of the five flavonoids decreased IL-17A production. Mice with experimentally induced autoimmune encephalomyelitis were used as an in vivo Th17 differentiation model. We focused on two flavonoids, NOB and SUD, and examined the effects of those flavonoids. NOB significantly suppressed Th17 cell proliferation and cytokine responses, but SUD only decreased proliferation responses. The results suggest that the suppressive effect of NOB on Th17 response in vivo is stronger than that of SUD.