Green tea epigallocatechin-3-gallate modulates differentiation of naïve CD4⁺ T cells into specific lineage effector cells.

CD4(+) T helper (Th) subsets Th1, Th9, and Th17 cells are implicated in inducing autoimmunity whereas regulatory T cells (Treg) have a protective effect. We and others have previously shown that epigallocatechin-3-gallate (EGCG) attenuates experimental autoimmune encephalomyelitis (EAE) and alters CD4(+) T cell subpopulations. In this study, we investigated how EGCG impacts differentiation of naïve CD4(+) T cells into different effector lineages and report that EGCG impeded Th1, Th9, and Th17 differentiation and prevented IL-6-induced suppression of Treg development. We further showed that EGCG inhibited T-bet, PU.1, and RORγt, the specific transcription factors for Th1, Th9, and Th17 differentiation, respectively. These effects, in turn, may be mediated by EGCG-induced downregulation of transducers p-STAT1 and p-STAT4 for Th1, and p-STAT3 for Th17. EGCG-induced change in Th17/Treg balance may be mediated by its inhibition of IL-6 signaling because EGCG inhibited soluble IL-6R, membrane gp130, and IL-6-induced phosphorylation of STAT3. This notion was further supported by the in vivo results showing inhibited IL-6 and soluble IL-6R but increased soluble gp130 levels in plasma from EAE mice fed EGCG. Together, our results suggest that EGCG modulates development of CD4(+) T cell lineages through impacting their respective and interactive regulatory networks ultimately leading to an attenuated autoimmune response.