期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2009
卷号：106
期号：31
页码：12885-12890
DOI：10.1073/pnas.0812530106
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The development of T helper (TH)17 and regulatory T (Treg) cells is reciprocally regulated by cytokines. Transforming growth factor (TGF)-{beta} alone induces FoxP3+ Treg cells, but together with IL-6 or IL-21 induces TH17 cells. Here we demonstrate that IL-9 is a key molecule that affects differentiation of TH17 cells and Treg function. IL-9 predominantly produced by TH17 cells, synergizes with TGF-{beta}1 to differentiate naive CD4+ T cells into TH17 cells, while IL-9 secretion by TH17 cells is regulated by IL-23. Interestingly, IL-9 enhances the suppressive functions of FoxP3+ CD4+ Treg cells in vitro, and absence of IL-9 signaling weakens the suppressive activity of nTregs in vivo, leading to an increase in effector cells and worsening of experimental autoimmune encephalomyelitis. The mechanism of IL-9 effects on TH17 and Tregs is through activation of STAT3 and STAT5 signaling. Our findings highlight a role of IL-9 as a regulator of pathogenic versus protective mechanisms of immune responses.
