Antigen‐specific Helios, Neuropilin‐1 Tregs induce apoptosis of autoreactive B cells via PD‐L1

J Gotot, E Dhana, H Yagita, R Kaiser… - … and Cell Biology, 2018 - Wiley Online Library
J Gotot, E Dhana, H Yagita, R Kaiser, I Ludwig‐Portugall, C Kurts
Immunology and Cell Biology, 2018Wiley Online Library
Regulatory T cells (Tregs) maintain self‐tolerance and prevent autoimmunity by controlling
autoreactive T cells. We recently demonstrated in vivo that Tregs can directly suppress auto‐
reactive B cells via programmed death ligand 1 (PD‐L1) that ligated PD‐1 on B cells and
caused them to undergo apoptosis. Here, we asked whether this mechanism is utilized by
thymus‐derived natural Tregs and/or by peripheral lymphoid tissue‐induced Tregs. We first
demonstrated that antigen‐specific PD‐L1‐expressing Tregs were induced in the draining …
Abstract
Regulatory T cells (Tregs) maintain self‐tolerance and prevent autoimmunity by controlling autoreactive T cells. We recently demonstrated in vivo that Tregs can directly suppress auto‐reactive B cells via programmed death ligand 1 (PD‐L1) that ligated PD‐1 on B cells and caused them to undergo apoptosis. Here, we asked whether this mechanism is utilized by thymus‐derived natural Tregs and/or by peripheral lymphoid tissue‐induced Tregs. We first demonstrated that antigen‐specific PD‐L1‐expressing Tregs were induced in the draining lymph node of autoantigen‐expressing tissue and characterized them by their lack of the transcription factor Helios and of the surface marker Neuropilin‐1 (Nrp‐1). Next, we established an in vitro co‐culture system to study the interaction between B cells and Treg subsets under controlled conditions. We found that Nrp Treg, but not Nrp+ Treg suppressed autoreactive B cells, whereas both were able to suppress T‐helper cells. Such suppression was antigen‐specific and was facilitated by PD‐L1/PD‐1‐induced apoptosis. Furthermore, it required physical cell contact and was MHC II‐restricted, providing an explanation for the antigen‐specificity of peripherally‐induced Tregs. These findings identify a role for peripherally induced Helios Nrp‐1 inducible Treg in controlling peripheral B‐cell tolerance against tissue auto‐antigens.
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