CXCR5-targeted chimeric antigen receptor T regulatory cells for the selective inhibition of follicular helper T cell and B cell interaction.

Abstract

The dysregulation of follicular helper T (Tfh) cell function, followed by the proliferation of self-reactive B cells, can lead to the development of autoimmune diseases. Recently, adaptive T regulatory cell (Treg) transfer therapy has attracted considerable attention for inducing effective immune tolerance owing to Tregs' diverse immune-inhibitory activities. However, preclinical studies and recent clinical trials of polyclonal Treg therapy have suggested further improving the efficacy of Treg therapy through targeted tissue specificity and local persistence by gene engineering. In this study, we reported a novel approach to specifically inhibit Tfh cells by CXC motif chemokine receptor 5-targeted chimeric antigen receptor (CXCR5-CAR) Tregs. Tregs expressing CAR against CXCR5 were generated from human peripheral blood mononuclear cells-derived Tregs. The phenotype and suppressive capacity of the engineered Tregs were evaluated using coculture assays with naïve T cells, circulating Tfh (cTfh) cells, or a combination of cTfh cells and naïve B cells through flow cytometry analysis. CXCR5-CAR Tregs induced more potent inhibition of circulating cTfh cell proliferation while maintaining similar suppressive properties on CXCR5-negative responder cells compared with non-selective polyclonal Tregs. The antigen-dependent activation of CXCR5-CAR Tregs was confirmed by latency-associated peptide (LAP) expression in the coculture with cTfh cells. In the coculture condition with both cTfh and naïve B cells, the activation of naïve B cells induced by cTfh cells was more effectively inhibited by CXCR5-CAR Tregs than by polyclonal Tregs. The results demonstrate the potential of CXCR5-CAR Tregs to effectively inhibit the Tfh-B cell response in autoimmune diseases, paving the way for further research to confirm their functional superiority in vivo. This novel approach offers promise for achieving local, long-term immune tolerance compared with existing approaches such as nonspecific immunosuppression and polyclonal Treg therapy.