Microenvironmental network of clonal CXCL13+CD4+ T cells and regulatory T cells in pemphigus chronic blisters

Pemphigus, a rare autoimmune bullous disease mediated by anti-desmoglein autoantibodies, can be controlled with systemic medication like rituximab and high-dose systemic corticosteroids combined with immunosuppressants. However, some patients continue to experience chronically recurrent blisters which require long-term maintenance systemic therapy.Skin with chronic blisters was obtained from patients with pemphigus. Immunologic properties of the skin were analyzed by immunofluorescence staining, bulk and single-cell RNA and TCR sequencing, and a highly multiplex imaging technique known as CO-Detection by indEXing (CODEX). Functional analyses were performed by flow cytometry and bulk RNA-sequencing using peripheral blood from healthy donors. Intralesional corticosteroid was injected into patient skin, and changes in chronically recurrent blisters were observed.We demonstrate the presence of skin tertiary lymphoid structures (TLSs) with desmoglein-specific B cells in chronic blisters from pemphigus patients. In the skin TLSs, CD4+ T cells predominantly produced CXCL13. These clonally expanded CXCL13+CD4+ T cells exhibited features of activated Th1-like cells and downregulated genes associated with T-cell receptor-mediated signaling. Regulatory T cells (Tregs) are in direct contact with CXCL13+CD4+ memory T cells and increased CXCL13 production of CD4+ T cells through IL-2 consumption and TGF-β stimulation. Lastly, Intralesional corticosteroid injection improved chronic blisters and reduce skin TLSs in patients with pemphigus.This study concludes that skin TLSs are associated with the persistence of chronically recurrent blisters in pemphigus patients, and the microenvironmental network involving CXCL13+CD4+ T cells and Tregs within these structures plays an important role in CXCL13 production.NCT04509570FUNDING. This work was supported by National Research Foundation of South Korea (grant NRF-2021R1C1C1007179) and Korea Drug Development Fund funded by Ministry of Science and ICT, Ministry of Trade, Industry, and Energy, and Ministry of Health and Welfare (grant RS-2022-00165917).