Dihydroartemisinin Alleviates Chronic Allograft Rejection by Inhibiting Tfh and B Cells While Promoting Treg Cells in Murine Cardiac Transplantation

Follicular helper T (Tfh), B and regulatory T (Treg) cells are involved in the pathogenesis of chronic rejection (CR) after transplantation. Dihydroartemisinin (DHA) is an antimalarial drug with anti-inflammatory activity; however, the effects and mechanisms of DHA on Tfh, B and Treg cells have not been comprehensively elucidated. The aim of this study was to investigate the effect of DHA on Tfh, B and Treg cells and its preventive effect on CR. In vitro assays demonstrated that DHA not only blocks the induction of Tfh cells and alleviates their supportive effect on B cell differentiation but also directly suppresses B cell activation, differentiation and antibody production. Additionally, DHA promotes the induction of Treg cells and enhances their stability in an inflammatory environment. In vivo studies showed that DHA effectively alleviated CR by suppressing neointimal hyperplasia, myocardial injury and interstitial fibrosis and reducing inflammatory cell infiltration and C4d deposition in allografts. Moreover, DHA decreased the levels of Tfh, germinal centre Tfh, B, germinal centre B, IgG-producing and plasma cells in recipients but increased Treg cell levels in recipients and allografts. Mechanistically, we confirmed that DHA inhibits Tfh cells by blocking IL-2-inducible T cell kinase signalling, suppresses B cells by blocking Bruton's tyrosine kinase signalling, and enhances Treg cells by blocking mTOR signalling while promoting STAT5 signalling. In conclusion, our results verified that DHA inhibits Tfh and B cells and enhances Treg cells to attenuate CR in mice, highlighting its potential applicability in the development of robust treatment options.