ADAR1 Inhibits Macrophage Apoptosis and Alleviates Sepsis-induced Liver Injury Through miR-122/BCL2A1 Signaling.

Background and Aims: As sepsis progresses, immune cell apoptosis plays regulatory roles in the pathogenesis of immunosuppression and organ failure. We previously reported that adenosine deaminases acting on RNA-1 (ADAR1) reduced intestinal and splenic inflammatory damage during sepsis. However, the roles and mechanism of ADAR1 in sepsis-induced liver injury remain unclear. Methods: We performed transcriptome and single-cell RNA sequencing of peripheral blood mononuclear cells (PBMCs) from patients with sepsis to investigate the effects of ADAR1 on immune cell activities. We also employed a cecal ligation and puncture (CLP) sepsis mouse model to evaluate the roles of ADAR1 in sepsis-induced liver injury. Finally, we treated murine RAW 264.7 macrophages with lipopolysaccharide to explore the underlying ADAR1-mediated mechanisms in sepsis. Results: PBMCs from patients with sepsis had obvious apoptotic morphological features. Single-cell RNA sequencing indicated that apoptosis-related pathways were enriched in monocytes, with significantly elevated ADAR1 and BCL2A1 expression in severe sepsis. CLP-induced septic mice had aggravated liver injury and Kupffer cell apoptosis that were largely alleviated by ADAR1 overexpression. ADAR1 directly bound to pre-miR-122 to modulate miR-122 biosynthesis. miR-122 was an upstream regulator of BCL2A1. Furthermore, ADAR1 also reduced macrophage apoptosis in mice with CLP-induced sepsis through the miR-122/BCL2A1 signaling pathway and protected against sepsis-induced liver injury. Conclusions: The findings show that ADAR1 alleviates macrophage apoptosis and sepsis-induced liver damage through the miR-122/BCL2A1 signaling pathway. The study provides novel insights into the development of therapeutic interventions in sepsis.