Sinomenine hydrochloride alleviates autoimmune myocarditis via suppressing Th1 cell induced-M1 macrophage pyroptosis

Background CD4 + T cells are crucial to the cardiac autoimmunity of myocarditis, with the underlying pathogenesis remaining unclear. Sinomenine hydrochloride, a natural compound from Sinomenium acutum , is reported to protect against some autoimmune diseases. This study aimed to elucidate the role of CD4 + T-helper 1 (Th1) cells in regulating inflammatory cell death and investigate the effect of sinomenine hydrochloride on Th1 cells and myocarditis. Methods: Male Balb/c mice were immunized with myosin heavy chain-α peptides to establish the experimental autoimmune myocarditis (EAM) model. RNA sequencing was used to investigate the functions of T cell subsets in the EAM and explore the effect of sinomenine hydrochloride. Flow cytometry was used to analyze the inhibitory effect of sinomenine hydrochloride on Th1 cells. Results: We observed a novel function of Th1 cells in promoting macrophage pyroptosis, thereby amplifying the immune response in the EAM. Further investigation revealed that the downstream molecule interferon regulatory factor 1 (IRF1) directly bound to the Casp1 gene and initiated its transcription for pyroptosis induction. To address Th1-induced pyroptosis, we found that sinomenine hydrochloride suppressed Th1 cell activation and differentiation in vitro, as well as Th1-induced pyroptosis, heart injury, and cardiac dysfunction in vivo. Further study indicated that sinomenine hydrochloride targeted at Gatm gene to disturb the arginine metabolism of T cells. Conclusions: Th1 cell-induced M1 macrophage pyroptosis is an essential pathogenic mechanism of EAM. Sinomenine hydrochloride suppresses Th1 cell arginine metabolism, potentially making it a practical approach to treating myocarditis.