Macrophage-derived exosome piR-50971 exacerbates sepsis-induced myocardial injury by inhibiting autophagy through the upregulation of N6-Methyladenosine modification of mTOR

Sepsis-induced myocardial injury (SIMI) is recognized as a severe complication of sepsis which characterized by a high mortality rate. Notably, the pathophysiology of SIMI involves complex mechanisms, including dysregulation of autophagy. Exosomes contribute to crucial biological processes during sepsis, modulating autophagy processes and facilitating communication between cells. PIWI-interacting RNAs (piRNAs) are highly expressed in myocardial tissue and exert cardiovascular regulation properties. Therefore, we investigated the role of macrophage-derived exosome piRNAs, specifically piR-50971, in SIMI and their impact on autophagy through N6-Methyladenosine (m⁶A) modification of mTOR.

A cecal ligation and puncture model was established to mimic the pathophysiological features of SIMI. Plasma exosomes were isolated and sequenced to characterize the expression of sepsis-related piRNAs. Bioinformatics analysis was employed to predict the potential regulatory mechanisms involving piR-50971. To investigate the direct interaction between piR-50971 and mTOR, a dual-luciferase reporter assay was conducted. Moreover, a methylated RNA immunoprecipitation assay was conducted to verify the involvement of piR-50971 in the m⁶A methylation modification of mTOR transcripts. Additionally, the m⁶A methylation level was assessed using dot blotting. Left ventricular ejection fraction and left ventricular fractional shortening of rats were detected by animal echocardiography. Transmission electron microscopy was used to detect autophagy flux in the myocardial tissue of rats in vivo. Cardiac enzymes were detected using a biochemical analyzer.

piR-50971 was identified as a key piRNA upregulated in plasma exosomes during SIMI, which was correlated with the inhibition of autophagy. Increased macrophage infiltration was observed in the myocardium of rats with SIMI. Additionally, cardiomyocytes treated with macrophage-derived exosomes exhibited impaired autophagy. RNA binding protein immunoprecipitation assay demonstrated an interaction between Wilms’ tumor 1-associated protein (WTAP) protein and mTOR mRNA. piR-50971 interacted with mTOR, leading to increased m⁶A modification through the regulation of WTAP and subsequent suppression of autophagy. Notably, this regulation upregulated mTOR translation, thereby inhibiting autophagy and exacerbating myocardial injury under septic conditions. In vivo experiments demonstrated that piR-50971 inhibition ameliorated myocardial injury and improved autophagy in rats with SIMI.

Our findings reveal a novel mechanism by which macrophage-derived exosome piR-50971 contributes to SIMI by suppressing autophagy via m⁶A modification of mTOR. Overall, our results implicate piR-50971 as a potential target for therapeutic intervention in sepsis-related myocardial dysfunction.