TSLP/dendritic cell axis promotes CD4⁺ T cell tolerance to the gut microbiome

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Abstract

Thymic stromal lymphopoietin (TSLP) overexpression is widely associated with atopy. However, TSLP is expressed in normal barrier organs, suggesting a homeostatic function. To determine the function of TSLP in barrier sites, we investigated the impact of endogenous TSLP signaling on the homeostatic expansion of CD4+ T cells in adult mice. Surprisingly, incoming CD4+ T cells induced lethal colitis in adult Rag1-knockout animals that lacked the TSLP receptor (Rag1KOTslprKO). Endogenous TSLP signaling was required for reduced CD4+ T cell proliferation, Treg differentiation, and homeostatic cytokine production. CD4+ T cell expansion in Rag1KOTslprKO mice was dependent on the gut microbiome. The lethal colitis was rescued by parabiosis between Rag1KOTslprKO and Rag1KO animals and wild-type dendritic cells (DCs) suppressed CD4+ T cell–induced colitis in Rag1KOTslprKO mice. A compromised T cell tolerance was noted in TslprKO adult colon, which was exacerbated by anti–PD-1 and anti–CTLA-4 therapy. These results reveal a critical peripheral tolerance axis between TSLP and DCs in the colon that blocks CD4+ T cell activation against the commensal gut microbiome.

Authors

Jonathan L. Messerschmidt, Marjan Azin, Kaitlin E. Dempsey, Shadmehr Demehri