A methoxyflavanone from the medicinal herb Perilla frutescens down-modulates Th17 response and ameliorates...

IL-17-producing T-helper 17 (Th17) cells are involved in the pathogenesis of autoimmune disorders such as rheumatoid arthritis (RA). Here, we show that a methoxyflavanone from the Asian medicinal herb Perilla frutescens (termed Perilla-derived methoxyflavanone, PDMF) suppresses Th17 response and collagen-induced arthritis (CIA), an animal model of RA. We found that co-stimulation with PDMF suppressed Th17 cell differentiation and inhibited IL-17A secretion by differentiated Th17 cells. In vivo administration of PDMF to a CIA mouse model significantly ameliorated the development of RA-like joint symptoms, accompanied by decreased IL-17A production. Mechanistically, PDMF neither suppresses Th17-inducing IL-6 signaling nor reciprocally expands regulatory T (Treg) cells, but rather negatively regulates T-cell receptor (TCR) signaling-driven activation of Akt, which is another positive regulator of Th17 cell differentiation. These results suggest that PDMF is useful in preventing RA and the pro-inflammatory Th17 response.