c-Jun N-Terminal Kinase-2 (JNK2) Plays a Crucial Role in Alcohol and Corticosterone-Induced Dysbiosis of Gut Microbiota and Tissue Injury at the Gut-Liver Axis
Authors: Basa Lohitha , Shukla Pradeep , Meena Avtar , Shashikanth Nitesh , Shekhar Chandra , Raju Preeti , Swarna Samhitha 
Published: May 2024

Introduction: About 15% of heavy drinkers develop liver disease, suggesting the “Multiple hit hypothesis” of Alcohol-Associated Liver Diseases (AALD). Chronic stress is a potential second hit in AALD pathogenesis. Our recent study showed that alcohol-induced gut and liver injury is exacerbated by chronic restraint stress or corticosterone. JNK2 plays an essential role in stress-induced cell injury. In this study, we investigated the role of JNK2 in ethanol (EtOH) and corticosterone-induced gut and liver injury and microbiota dysbiosis in mice. Methods: Wildtype (WT) and JNK2 knockout (JNK2-KO) mice (male and female; 8-10 wks) were fed a Lieber-DiCarli liquid diet with or without EtOH (0% 2d, 1% 2d, 2% 2d, 4% 1wk, 5% 1wk, & 6% 1wk). Control groups were pair-fed isocaloric EtOH-free diet. One group of pair-fed and EtOH-fed WT and JNK2-KO mice were administered corticosterone (CORT, 25 mg/kg/day; s.c.). Intestinal permeability was measured by vascular-to-luminal flux of FITC-inulin in vivo, tight junction (TJ) and adherens junction (AJ) integrity was assessed by confocal microscopy for occludin, ZO-1, E-cadherin, and β-catenin, and mucosal inflammation by RT-PCR for cytokines/chemokines. Plasma lipopolysaccharide (LPS) and cytokines were measured to evaluate endotoxemia and systemic inflammation. Liver damage was assessed by measuring plasma AST/ALT, liver triglyceride, and cytokine/chemokine mRNA. Gut microbiota was analyzed by 16S rRNA sequencing of colonic flushing followed by bioinformatics analyses. Results and conclusion: In WT mice, EtOH feeding increased intestinal permeability, disrupted epithelial TJ and AJ, and elevated mucosal cytokine expression, indicating epithelial barrier dysfunction and mucosal inflammation. EtOH increased plasma LPS and cytokine/chemokine levels, indicating endotoxemia and systemic inflammation. Plasma AST/ALT and liver triglyceride levels were increased, indicating EtOH-induced liver damage. CORT significantly elevated EtOH-induced intestinal permeability, TJ/AJ disruption, endotoxemia, systemic inflammation, and liver damage in WT mice. These effects of EtOH and CORT were absent in JNK2-KO mice. Microbiota α-diversity was higher in JNK2-KO mice than in WT mice, and β-diversity analysis showed that the microbiota composition in WT mice differed from that of KO mice. Microbiota α- and β-diversities were altered by EtOH and CORT in WT mice but not in JNK2-KO mice. The relative abundance of Nocardiaceae and Verrucomicrobiaceae was high, and Ruminococcaceae and Bacillaceae were low in KO mice. CORT decreased the abundance of Caulobacteriaceae and Ruminococcaceae and increased Verrucomicrobiaceae and Lactobacillaceae in WT but not KO mice. EtOH increased Ruminococcaceae and Bacillaceae and decreased Lactobacillaceae in WT mice but not KO mice. CORT-induced modulation of EtOH-induced microbiota dysbiosis was observed in WT mice but not KO mice. In conclusion, these data demonstrate that JNK2 regulates gut microbiota in mice, and JNK2 deficiency confers resistance to alcohol and corticosterone-induced tissue injury and microbiota dysbiosis.

Acknowledgements: NIH/NIAAA - R01AA012307, AA029270; VA - IO1BX003014.

This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.