Low-intensity pulsed ultrasound protects from inflammatory dilated cardiomyopathy through inciting extracellular vesicles.

Aims CD4⁺ T cells are activated during inflammatory dilated cardiomyopathy (iDCM) development to induce immunogenic responses that damage the myocardium. Low-intensity pulsed ultrasound (LIPUS), a novel physiotherapy for cardiovascular diseases, has recently been shown to modulate inflammatory responses. However, its efficacy in iDCM remains unknown. Here, we investigated whether LIPUS could improve the severity of iDCM by orchestrating immune responses and explored its therapeutic mechanisms. Methods and results In iDCM mice, LIPUS treatment reduced cardiac remodelling and dysfunction. Additionally, CD4⁺ T-cell inflammatory responses were suppressed. LIPUS increased Treg cells while decreasing Th17 cells. LIPUS mechanically stimulates endothelial cells, resulting in increased secretion of extracellular vesicles (EVs), which are taken up by CD4⁺ T cells and alter their differentiation and metabolic patterns. Moreover, EVs selectively loaded with microRNA (miR)-99a are responsible for the therapeutic effects of LIPUS. The hnRNPA2B1 translocation from the nucleus to the cytoplasm and binding to caveolin-1 and miR-99a confirmed the upstream mechanism of miR-99a transport. This complex is loaded into EVs and taken up by CD4⁺ T cells, which further suppress mTOR and TRIB2 expression to modulate cellular differentiation. Conclusion Our findings revealed that LIPUS uses an EVs-dependent molecular mechanism to protect against iDCM progression. Therefore, LIPUS is a promising new treatment option for iDCM. [ABSTRACT FROM AUTHOR]