Regulation of the expression of GARP/latent TGF-?1 complexes on mouse T cells and their role in regulatory T cell and Th17 differentiation.

ABSTRACT: GARP/LRRC32 was defined as a marker of activated human regulatory T cells (Tregs) that is responsible for surface localization of latent TGF-?1. We find that GARP and latent TGF-?1 are also found on mouse Tregs activated via TCR stimulation; however, in contrast to human Tregs, GARP is also expressed at a low level on resting Tregs. The expression of GARP can be upregulated on mouse Tregs by IL-2 or IL-4 exposure in the absence of TCR signaling. GARP is expressed at a low level on Tregs within the thymus, and Treg precursors from the thymus concomitantly express GARP and Foxp3 upon exposure to IL-2. The expression of GARP is independent of TGF-?1 and TGF-?1 loading into GARP and is independent of furin-mediated processing of pro-TGF-?1 to latent TGF-?1. Specific deletion of GARP in CD4(+) T cells results in lack of expression of latent TGF-?1 on activated Tregs. GARP-deficient Tregs develop normally, are present in normal numbers in peripheral tissues, and are fully competent suppressors of the activation of conventional T cells in vitro. Activated Tregs expressing GARP/latent TGF-?1 complexes are potent inducers of Th17 differentiation in the presence of exogenous IL-6 and inducers of Treg in the presence of IL-2. Induction of both Th17-producing cells and Tregs is caused preferentially by Tregs expressing the latent TGF-?1/GARP complex on their cell surface rather than by secreted latent TGF-?1.

SUBMITTER: Edwards JP 

PROVIDER: S-EPMC3668701 | biostudies-literature | 2013 Jun

REPOSITORIES: biostudies-literature