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Diet-induced gut dysbiosis and inflammation: Key drivers of obesity-driven NASH. iScience 2022; 26:105905. [PMID: 36691622 PMCID: PMC9860397 DOI: 10.1016/j.isci.2022.105905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Sucrose, the primary circulating sugar in plants, contains equal amounts of fructose and glucose. The latter is the predominant circulating sugar in animals and thus the primary fuel source for various tissue and cell types in the body. Chronic excessive energy intake has, however, emerged as a major driver of obesity and associated pathologies including nonalcoholic fatty liver diseases (NAFLD) and the more severe nonalcoholic steatohepatitis (NASH). Consumption of a high-caloric, western-style diet induces gut dysbiosis and inflammation resulting in leaky gut. Translocation of gut-derived bacterial content promotes hepatic inflammation and ER stress, and when either or both of these are combined with steatosis, it can cause NASH. Here, we review the metabolic links between diet-induced changes in the gut and NASH. Furthermore, therapeutic interventions for the treatment of obesity and liver metabolic diseases are also discussed with a focus on restoring the gut-liver axis.
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Steiner CA, Cartwright IM, Taylor CT, Colgan SP. Hypoxia-inducible factor as a bridge between healthy barrier function, wound healing, and fibrosis. Am J Physiol Cell Physiol 2022; 323:C866-C878. [PMID: 35912990 PMCID: PMC9467472 DOI: 10.1152/ajpcell.00227.2022] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 07/07/2022] [Accepted: 07/23/2022] [Indexed: 11/22/2022]
Abstract
The healthy mammalian intestine is lined by a single layer of epithelial cells. These cells provide a selectively permeable barrier to luminal contents and normally do so in an efficient and effective manner. Barrier function in the healthy mucosa is provided via several mechanisms including epithelial junctional complexes, mucus production, as well as mucosal-derived antimicrobial proteins. As tissue metabolism is central to the maintenance of homeostasis in the mucosa, intestinal [Formula: see text] levels are uniquely low due to counter-current blood flow and the presence of the microbiota, resulting in the stabilization of the transcription factor hypoxia-inducible factor (HIF). Ongoing studies have revealed that HIF molds normal intestinal metabolism and is central to the coordination of barrier regulation during both homeostasis and active disease. During acute inflammation, HIF is central to controlling the rapid restitution of the epithelium consistent with normal wound healing responses. In contrast, HIF may also contribute to the fibrostenotic response associated with chronic, nonresolving inflammation. As such, HIF may function as a double-edged sword in the overall course of the inflammatory response. Here, we review recent literature on the contribution of HIF to mucosal barrier function, wound healing, and fibrosis.
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Affiliation(s)
- Calen A Steiner
- Division of Gastroenterology and Hepatology, University of Colorado Anschutz Medical Campus, Aurora, Colorado
- Department of Medicine and the Mucosal Inflammation Program, University of Colorado School of Medicine, Aurora, Colorado
| | - Ian M Cartwright
- Division of Gastroenterology and Hepatology, University of Colorado Anschutz Medical Campus, Aurora, Colorado
- Department of Medicine and the Mucosal Inflammation Program, University of Colorado School of Medicine, Aurora, Colorado
- Rocky Mountain Regional Veterans Affairs Medical Center, Aurora, Colorado
| | - Cormac T Taylor
- School of Medicine, Conway Institute and Systems Biology Ireland, University College Dublin, Dublin, Ireland
| | - Sean P Colgan
- Division of Gastroenterology and Hepatology, University of Colorado Anschutz Medical Campus, Aurora, Colorado
- Department of Medicine and the Mucosal Inflammation Program, University of Colorado School of Medicine, Aurora, Colorado
- Rocky Mountain Regional Veterans Affairs Medical Center, Aurora, Colorado
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Wen J, Lyu P, Stolzer I, Xu J, Gießl A, Lin Z, Andreev D, Kachler K, Song R, Meng X, Cao S, Guggino G, Ciccia F, Günther C, Schett G, Bozec A. Epithelial HIF2α expression induces intestinal barrier dysfunction and exacerbation of arthritis. Ann Rheum Dis 2022; 81:annrheumdis-2021-222035. [PMID: 35710307 DOI: 10.1136/annrheumdis-2021-222035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Accepted: 05/14/2022] [Indexed: 11/04/2022]
Abstract
OBJECTIVE To investigate how the mucosal barrier in the intestine influences the development of arthritis, considering that metabolic changes in the intestinal epithelium influence its barrier function. METHODS Intestinal hypoxia inducible factor (HIF)-2α expression was assessed before, at onset and during experimental arthritis and human rheumatoid arthritis (RA). Intestinal epithelial cell-specific HIF2α conditional knock-out mice were generated (HIF2α∆IEC) and subjected to collagen-induced arthritis. Clinical and histological courses of arthritis were recorded; T-cell and B-cell subsets were analysed in the gut and secondary lymphatic organs; and intestinal epithelial cells were subjected to molecular mRNA sequencing in HIF2α∆IEC and littermate control mice. The gut intestinal HIF2α target genes were delineated by chromatin immunoprecipitation and luciferase experiments. Furthermore, pharmacological HIF2α inhibitor PT2977 was used for inhibition of arthritis. RESULTS Intestinal HIF2α expression peaked at onset of experimental arthritis and RA. Conditionally, deletion of HIF2α in gut epithelial cells inhibited arthritis and was associated with improved intestinal barrier function and less intestinal and lymphatic Th1 and Th17 activation. Mechanistically, HIF2α induced the transcription of the pore-forming claudin (CLDN)-15, which inhibits intestinal barrier integrity. Furthermore, treatment with HIF2α inhibitor decreased claudin-15 expression in epithelial cells and inhibited arthritis. CONCLUSION These findings show that the HIF2α-CLDN15 axis is critical for the breakdown of intestinal barrier function at onset of arthritis, highlighting the functional link between intestinal homeostasis and arthritis.
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Affiliation(s)
- Jinming Wen
- Department of Internal Medicine 3, Rheumatology and Immunology, Friedrich-Alexander-University Erlangen-Nürnberg (FAU) and Universitätsklinikum Erlangen, Erlangen, Germany
| | - Pang Lyu
- Department of Internal Medicine 3, Rheumatology and Immunology, Friedrich-Alexander-University Erlangen-Nürnberg (FAU) and Universitätsklinikum Erlangen, Erlangen, Germany
| | - Iris Stolzer
- Department of Internal Medicine 1, Friedrich-Alexander-University Erlangen-Nürnberg (FAU) and Universitätsklinikum Erlangen, Erlangen, Germany
| | - Jin Xu
- Department of Orthopaedic Surgery, Sun Yat-Sen University, Guangzhou, China
| | - Andreas Gießl
- Department of Animal Physiology, Friedrich-Alexander-University Erlangen-Nürnberg (FAU) and Universitätsklinikum Erlangen, Erlangen, Germany
| | - Zhen Lin
- Department of Internal Medicine 3, Rheumatology and Immunology, Friedrich-Alexander-University Erlangen-Nürnberg (FAU) and Universitätsklinikum Erlangen, Erlangen, Germany
| | - Darja Andreev
- Department of Internal Medicine 3, Rheumatology and Immunology, Friedrich-Alexander-University Erlangen-Nürnberg (FAU) and Universitätsklinikum Erlangen, Erlangen, Germany
| | - Katerina Kachler
- Department of Internal Medicine 3, Rheumatology and Immunology, Friedrich-Alexander-University Erlangen-Nürnberg (FAU) and Universitätsklinikum Erlangen, Erlangen, Germany
| | - Rui Song
- Department of Internal Medicine 3, Rheumatology and Immunology, Friedrich-Alexander-University Erlangen-Nürnberg (FAU) and Universitätsklinikum Erlangen, Erlangen, Germany
| | - Xianyi Meng
- Department of Internal Medicine 3, Rheumatology and Immunology, Friedrich-Alexander-University Erlangen-Nürnberg (FAU) and Universitätsklinikum Erlangen, Erlangen, Germany
| | - Shan Cao
- Department of Internal Medicine 3, Rheumatology and Immunology, Friedrich-Alexander-University Erlangen-Nürnberg (FAU) and Universitätsklinikum Erlangen, Erlangen, Germany
| | - Giuliana Guggino
- Rheumatology Section, Department of Health Promotion, Mother and Child Care, Internal Medicine and Medical Specialties, University Hospital P. Giaccone, Palermo, Italy
| | - Francesco Ciccia
- Precision Medicine, Università degli Studi della Campania Luigi Vanvitelli, Napoli, Italy
| | - Claudia Günther
- Department of Internal Medicine 1, Friedrich-Alexander-University Erlangen-Nürnberg (FAU) and Universitätsklinikum Erlangen, Erlangen, Germany
| | - Georg Schett
- Department of Internal Medicine 3, Rheumatology and Immunology, Friedrich-Alexander-University Erlangen-Nürnberg (FAU) and Universitätsklinikum Erlangen, Erlangen, Germany
| | - Aline Bozec
- Department of Internal Medicine 3, Rheumatology and Immunology, Friedrich-Alexander-University Erlangen-Nürnberg (FAU) and Universitätsklinikum Erlangen, Erlangen, Germany
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Dey P, Chaudhuri SR, Efferth T, Pal S. The intestinal 3M (microbiota, metabolism, metabolome) zeitgeist - from fundamentals to future challenges. Free Radic Biol Med 2021; 176:265-285. [PMID: 34610364 DOI: 10.1016/j.freeradbiomed.2021.09.026] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Revised: 09/18/2021] [Accepted: 09/30/2021] [Indexed: 12/12/2022]
Abstract
The role of the intestine in human health and disease has historically been neglected and was mostly attributed to digestive and absorptive functions. In the past two decades, however, discoveries related to human nutrition and intestinal host-microbe reciprocal interaction have established the essential role of intestinal health in the pathogenesis of chronic diseases and the overall wellbeing. That transfer of gut microbiota could be a means of disease phenotype transfer has revolutionized our understanding of chronic disease pathogenesis. This narrative review highlights the major concepts related to intestinal microbiota, metabolism, and metabolome (3M) that have facilitated our fundamental understanding of the association between the intestine, and human health and disease. In line with increased interest of microbiota-dependent modulation of human health by dietary phytochemicals, we have also discussed the emerging concepts beyond the phytochemical bioactivities which emphasizes the integral role of microbial metabolites of parent phytochemicals at extraintestinal tissues. Finally, this review concludes with challenges and future prospects in defining the 3M interactions and has emphasized the fact that, it takes 'guts' to stay healthy.
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Affiliation(s)
- Priyankar Dey
- Department of Biotechnology, Thapar Institute of Engineering and Technology, Patiala, Punjab, India.
| | - Saumya Ray Chaudhuri
- Council of Scientific and Industrial Research (CSIR), Institute of Microbial Technology, Chandigarh, India
| | - Thomas Efferth
- Department of Pharmaceutical Biology, Institute of Pharmaceutical and Biomedical Sciences, Johannes Gutenberg University, Mainz, Germany
| | - Sirshendu Pal
- Mukherjee Hospital, Mitra's Clinic and Nursing Home, Siliguri, West Bengal, India
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Zheng L, Kelly CJ, Colgan SP. Physiologic hypoxia and oxygen homeostasis in the healthy intestine. A Review in the Theme: Cellular Responses to Hypoxia. Am J Physiol Cell Physiol 2015; 309:C350-60. [PMID: 26179603 DOI: 10.1152/ajpcell.00191.2015] [Citation(s) in RCA: 314] [Impact Index Per Article: 34.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
In recent years, the intestinal mucosa has proven to be an intriguing organ to study tissue oxygenation. The highly vascularized lamina propria juxtaposed to an anaerobic lumen containing trillions of metabolically active microbes results in one of the most austere tissue microenvironments in the body. Studies to date have determined that a healthy mucosa contains a steep oxygen gradient along the length of the intestine and from the lumen to the serosa. Advances in technology have allowed multiple independent measures and indicate that, in the healthy mucosa of the small and large intestine, the lumen-apposed epithelia experience Po2 conditions of <10 mmHg, so-called physiologic hypoxia. This unique physiology results from a combination of factors, including countercurrent exchange blood flow, fluctuating oxygen demands, epithelial metabolism, and oxygen diffusion into the lumen. Such conditions result in the activation of a number of hypoxia-related signaling processes, including stabilization of the transcription factor hypoxia-inducible factor. Here, we review the principles of mucosal oxygen delivery, metabolism, and end-point functional responses that result from this unique oxygenation profile.
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Affiliation(s)
- Leon Zheng
- Department of Medicine and Mucosal Inflammation Program, University of Colorado School of Medicine, Aurora, Colorado
| | - Caleb J Kelly
- Department of Medicine and Mucosal Inflammation Program, University of Colorado School of Medicine, Aurora, Colorado
| | - Sean P Colgan
- Department of Medicine and Mucosal Inflammation Program, University of Colorado School of Medicine, Aurora, Colorado
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Role of TLR4/NF-κB in damage to intestinal mucosa barrier function and bacterial translocation in rats exposed to hypoxia. PLoS One 2012; 7:e46291. [PMID: 23082119 PMCID: PMC3474812 DOI: 10.1371/journal.pone.0046291] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2012] [Accepted: 08/29/2012] [Indexed: 12/14/2022] Open
Abstract
The role of Toll-like receptor 4 (TLR4)/nuclear factor-kappa-B (NF-κB) in intestinal mucosal barrier damage and bacterial translocation under hypoxic exposure is unclear. Here, we investigated their role using an acute hypobaric hypoxia model. Adult Sprague-Dawley rats were divided into control (C), hypoxia (H), hypoxia+NF-κB inhibitor pyrrolidinedithiocarbamic acid (PDTC) (100 mg. kg) (HP), hypoxia+0.5 mg/kg lipopolysaccharide (HPL), and hypoxia+PDTC+LPS (HPL) group. Except control group, other four groups were placed in a hypobaric chamber set at 7000 m. Samples were collected at 72 h after pressure reduction. Damage in ultrastructure of the intestinal tract was examined by transmission electron microscopy and bacterial translocation was detected by cultivation. Kinetic turbidimetric assay was used to measure the serum LPS. ELISA was performed to detect TNF-α and IL-6 serum concentrations. Fluorescent quantitative RT-PCR was used to measure TLR4 mRNA levels was measured using quantitative RT-PCR and protein of NF-κB p65 was measured by western blotting. Different degrees of intestinal mucosa damage were observed in groups H and HL. The damage was significantly alleviated after blockage of the TLR4/NF-κB signaling pathway. PDTC- treatment also reversed hyoxia- and LPS-induced bacterial translocation rate and increased serum levels of LPS, TNF-α, and IL-6. TLR4 mRNA levels and NF-κB p65 expression were consistent with the serum factor results. This study suggested that TLR4 and NF-κB expression increased in rat intestinal tissues after acute hypoxia exposure. PDTC-treatment reversed TLR4 and NF-κB upregulation and alleviated damage to the intestinal tract and bacterial translocation. Thus, the TLR4/NF-κB signaling pathway may be critical to the mechanism underlying hypoxia-induced damage to intestinal barrier function and bacterial translocation.
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