Myeloid Piezo1 Drives Cardiac Repair Through Orai1-Rac1-Dependent Efferocytosis

Monocytes/macrophages orchestrate myocardial remodeling through efferocytosis, the calcium-dependent clearance of apoptotic cells. While the mechanosensitive channel Piezo1 is known to modulate calcium influx in cardiac and immune contexts, its myeloid-specific role in postinfarction healing remains elusive.

Myeloid Piezo1-specific knockout mice (Piezo1^∆LysM) were established, and left anterior descending coronary artery ligation was used to induce myocardial infarction. Cardiac function was detected by echocardiography and magnetic resonance imaging, and infarct size was measured by 2,3,5-triphenyl-tetrazolium chloride staining and hematoxylin and eosin staining. Inflammatory mediators were measured by flow cytometry, immunofluorescence, and real-time polymerase chain reaction. Intracellular Ca²⁺ measurements and patch-clamp were conducted to detect calcium influx and current. Through single-cell RNA sequencing, the underlying mechanisms of efferocytosis were subsequently validated via Western blot, targeted cell transfection, and macrophage-cardiomyocyte coculture assays.

Myeloid-specific Piezo1 deficiency improved cardiac function and alleviated myocardial fibrosis at 3, 14, and 28 days post-myocardial infarction. Moreover, Piezo1 deletion increased production of antiinflammatory cytokines 3 days post-myocardial infarction. Single-cell RNA sequencing revealed that the efferocytosis-associated genes were upregulated in the Piezo1^∆LysM group. Mechanistically, myeloid Piezo1 deletion enhanced Orai1 expression and calcium influx, which facilitated macrophage efferocytosis. In vitro, these changes were recapitulated by Orai1 knockdown and Orai1 overexpression in bone marrow-derived macrophages. In vivo, Orai1 knockdown impaired efferocytosis and attenuated cardiac protection, whereas Orai1 overexpression enhanced it. Furthermore, Piezo1 deletion promoted Rac1 activation and cytoskeletal remodeling, thereby enhancing apoptotic cell clearance. In addition, myeloid Piezo1 deletion augmented lysosomal acidification and phagosome maturation, contributing to efficient apoptotic cell degradation.

Our study uncovered a previously unrecognized Piezo1-Orai1-Rac1 signaling axis that regulates macrophage efferocytosis and lysosomal maturation following myocardial infarction.