Melatonin Attenuates Sepsis-Induced Small-Intestine Injury by Upregulating SIRT3-Mediated Oxidative-Stress Inhibition, Mitochondrial Protection, and Autophagy Induction

• DOI: 10.3389/fimmu.2021.625627
• Publication Date: 2021-03-12T05:14:22Z
• Authors: Siqi Xu; Lulan Li; Jie Wu; Sheng An; Haihong Fang; Yunyang Han; Qiaobing Huang; Zhongqing Chen; Zhenhua Zeng
• Keywords: 0301 basic medicine; autophagy; Immunology; melatonin; Antioxidants; sepsis; SIRT3; 03 medical and health sciences; Sirtuin 1; Sepsis; Sirtuin 3; Intestine, Small; Autophagy; Animals; Intestinal Mucosa; Melatonin; Mice, Knockout; RC581-607; Mitochondria; 3. Good health; mitochondria; Mice, Inbred C57BL; Disease Models, Animal; Oxidative Stress; Immunologic diseases. Allergy; Inflammation Mediators; small intestine

Melatonin reportedly alleviates sepsis-induced multi-organ injury by inducing autophagy and activating class III deacetylase Sirtuin family members (SIRT1–7). However, whether melatonin attenuates small-intestine injury along with the precise underlying mechanism remain to be elucidated. To investigate this, we employed cecal ligation and puncture (CLP)- or endotoxemia-induced sepsis mouse models and confirmed that melatonin treatment significantly prolonged the survival time of mice and ameliorated multiple-organ injury (lung/liver/kidney/small intestine) following sepsis. Melatonin partially protected the intestinal barrier function and restored SIRT1 and SIRT3 activity/protein expression in the small intestine. Mechanistically, melatonin treatment enhanced NF-κB deacetylation and subsequently reduced the inflammatory response and decreased the TNF-α, IL-6, and IL-10 serum levels; these effects were abolished by SIRT1 inhibition with the selective blocker, Ex527. Correspondingly, melatonin treatment triggered SOD2 deacetylation and increased SOD2 activity and subsequently reduced oxidative stress; this amelioration of oxidative stress by melatonin was blocked by the SIRT3-selective inhibitor, 3-TYP, and was independent of SIRT1. We confirmed this mechanistic effect in a CLP-induced sepsis model of intestinal SIRT3 conditional-knockout mice, and found that melatonin preserved mitochondrial function and induced autophagy of small-intestine epithelial cells; these effects were dependent on SIRT3 activation. This study has shown, to the best of our knowledge, for the first time that melatonin alleviates sepsis-induced small-intestine injury, at least partially, by upregulating SIRT3-mediated oxidative-stress inhibition, mitochondrial-function protection, and autophagy induction.