Abstract Body (Do not enter title and authors here): Phagocytic clearance of dying cells by efferocytosis is pivotal for the inflammation resolution and cardiac repair after myocardial infarction (MI). Macrophages are considered to be key phagocytes involved in efferocytosis. Here, we aimed to identify the role of mechanosensor Piezo1 in macrophage efferocytosis and ventricular remodeling during MI.
Double immunofluorescent staining of heart sections showed that Piezo1 was increased and the colocalization of Piezo1 and F4/80 was also increased in the infarcted area from 3 days to 4 weeks after MI. The mRNA and protein expression levels of Piezo1 were also increased in BMDMs isolated from mice 3 days and 7 days after MI compared to mice in sham groups. Piezo1^ΔLyz2 mice exhibited a significant amelioration in left ventricular function and remodeling after MI, accompanied with less accumulation of apoptotic cardiomyocytes and an increased index of in vivo efferocytosis in the border area. In the in vitro study, we found significantly enhanced uptake of apoptotic cells by Piezo1^ΔLyz2 macrophages compared with Piezo1^fl/fl macrophages. Furthermore, Piezo1 activation by Yoda1 induces defective efferocytosis in both BMDMs and PMs. RNA-seq analysis revealed that Yoda1 significantly increased the phagocytosis related genes, in which SLC7A11 has the most significant difference. Yoda1 significantly increased mRNA and protein expression levels of SLC7A11, while Piezo1^ΔLyz2 macrophages showed significantly reduced SLC7A11 mRNA expression. The small interfering RNA (siRNA) mediated SLC7A11 knockdown or erastin-mediated SLC7A11 inhibition effectively reversed Piezo1 induced defective efferocytosis in BMDMs. From four reported transcription factors, we found ATF4 is the upstream regulator of SLC7A11 expression in BMDMs after Piezo1 activation. The calcium chelator BAPTAN also significantly blocked the upregulated ATF4 and SLC7A11 in Yoda1-treated BMDMs. Finally, macrophage specific knockdown of SLC7a11 by intramedullary injection of AAV2-SLC7A11-shRNA significantly increased efferocytosis, reduced apoptotic cardiomyocytes, and ameliorated left ventricular remodeling and function after MI.
Conclusions: We reveal a novel role of Piezo1 in the insufficient macrophage efferocytosis during MI and identified the Ca²⁺/ATF4/SLC7A11 mediates the Piezo1 induced impaired macrophage efferocytosis.