Melatonin Alleviates Chronic Intermittent Hypoxia-induced Microbiota Dysbiosis and Attenuates Intestinal Barrier Dysfunction via STAT3/Th17 signalling pathway

Abstract

AbstractBackground:Chronic intermittent hypoxia (CIH) triggers subclinical intestinal barrier disruption prior to systemic low-grade inflammation. Increasing evidence suggests therapeutic effects of melatonin on systemic inflammation and gut microbiota remodelling. However, whether and how melatonin alleviates CIH-induced intestinal barrier dysfunction remains unclear.Methods:C57BL/6J mice and Caco-2 cell line were treated. We evaluated gut barrier function spectrophotometrically using fluorescein isothiocyanate (FITC)-labelled dextran. Immunohistochemical and immunofluorescent staining were used to detect morphological changes in the mechanical barrier. Western blotting (WB) and quantitative real-time polymerase chain reaction (qRT-PCR) revealed the expression of tight junctions, signal transducer and activator of transcription 3 (STAT3) levels. 16S rRNA analysis of the colonic contents microflora. Flow cytometry was used to detect cytokines and Th17 cells with and without melatonin supplementation.Results: We found that CIH could induce colonic mucosal injury, including reduction in the number of goblet cells and over expression of intestinal tight junction proteins CIH could decrease the abundance of the beneficial generaClostridium,Akkermansia,andBacteroides, while increasing the abundance of the pathogenic generaDesulfovibrioandBifidobacterium. Finally, CIH facilitated Th17 differentiation via the phosphorylation of signal transducer and activator of transcription 3 (STAT3)in vitroand elevated the circulating pro-inflammatory cytokine including interleukin (IL)-1β, IL-6, tumor necrosis factor-α, tumor growth factor-β, IL-17A, IL-17F, IL-21, IL-22, IL-23, and C-C motif chemokine ligand 20 in vivo. Melatonin supplementation ameliorated CIH-induced intestinal mucosal injury, gut microbiota dysbiosis, enteric Th17 polarization, and systemic low-grade inflammation reactions mentioned-above.Conclusions:Melatonin attenuated CIH-induced intestinal barrier dysfunction by regulating gut flora dysbiosis, mucosal epithelium integrity, and Th17 polarization via STAT3 signalling.