Protective effect of low-intensity pulsed ultrasound on immune checkpoint inhibitor-related myocarditis via fine-tuning CD4+ T-cell differentiation

Purpose Immune checkpoint inhibitors (ICIs) have transformed traditional cancer treatments. Specifically, ICI-related myocarditis is an immune-related adverse event (irAE) with high mortality. ICIs activate CD4(+) T-lymphocyte reprogramming, causing an imbalance between Th17 and Treg cell differentiation, ultimately leading to myocardial inflammatory damage. Low-intensity pulsed ultrasound (LIPUS) can limit inflammatory responses, with positive therapeutic effects across various cardiovascular inflammatory diseases; however, its role in the pathogenesis of ICI-related myocarditis and CD4+ T-cell dysfunction remains unclear. Accordingly, this study investigated whether LIPUS can alleviate ICI-related myocarditis inflammatory damage and, if so, aimed to elucidate the beneficial effects of LIPUS and its underlying molecular mechanisms.Methods An in vivo model of ICI-related myocarditis was obtained by intraperitonially injecting male A/J mice with an InVivoPlus anti-mouse PD-1 inhibitor. LIPUS treatment was performed via an ultrasound-guided application to the heart via the chest wall. The echocardiographic parameters were observed and cardiac function was assessed using an in vivo imaging system. The expression of core components of the HIPPO pathway was analyzed via western blotting.Results LIPUS treatment reduced cardiac immune responses and inflammatory cardiac injury. Further, LIPUS treatment alleviated the inflammatory response in mice with ICI-related myocarditis. Mechanistically, in the HIPPO pathway, the activation of Mst1-TAZ axis improved autoimmune inflammation by altering the interaction between the transcription factors FOXP3 and ROR gamma t and regulating the differentiation of Treg and Th17 cells.Conclusion LIPUS therapy was shown to reduce ICI-related myocarditis inflammatory damage and improve cardiac function, representing an exciting finding for irAEs treatment.