LACTOBACILLUS MURINUS ACTIVATES THE ARYL HYDROCARBON RECEPTOR TO ATTENUATE TNF-ALPHA-INDUCED PRO-INFLAMMATORY RESPONSES IN HUMAN INTESTINAL EPITHELIAL CELLS. (22nd January 2022)

• Record Type: Journal Article
• Authors: Ahmed, Husnain; Bell, Julia; Mansfield, Linda
• Is Part Of: Inflammatory bowel diseases. Volume 28(2022)Supplement 1
• Page Start: S65
• Page End: S65
• Publication Date: 2022-01-22
• Subjects: Inflammatory bowel diseases -- Periodicals; Colitis, Ulcerative -- Periodicals; Crohn Disease -- Periodicals; Inflammatory Bowel Diseases -- Periodicals; 616.344
• DOI: 10.1093/ibd/izac015.105
• Languages: English
• ISSNs: 1078-0998

Abstract

Abstract: BACKGROUND: Anti-TNF-alpha therapy is an established treatment modality for inflammatory bowel disease (IBD). Yet up to 30% of patients do not respond to anti-TNF-alpha therapy (primary non-responders), and almost 50% of responders lose clinical efficacy over time (secondary non-responders). Furthermore, numerous safety concerns are associated with the long-term use of anti-TNF-alpha agents. Anti-TNF-alpha therapy safety concerns and the increased incidence of non-responders have driven the need to develop innovative strategies to treat IBD. OBJECTIVE: A potential alternative to anti-TNF-alpha therapy is the use of novel probiotics capable of attenuating the damaging effects of TNF-alpha on the intestinal epithelium. We hypothesized that Lactobacillus murinus attenuates TNF-alpha induced pro-inflammatory responses and decreases barrier disruption in human intestinal epithelial cells (Caco-2) by activating the aryl hydrocarbon receptor (AhR). METHODS: We used Caco-2 cells grown on Transwell inserts to model the human intestinal epithelial barrier. Transepithelial Electrical Resistance (TEER) was measured to evaluate the formation of tight junctions. Once TEER reached 500 ohms per cm 2, the cells were considered to have formed tight junctions. To induce pro-inflammatory responses, Caco-2 cell monolayers were treated with increasing doses of TNF-alpha (0.1, 1 and 10 ng/ml). Caco-2 cell monolayers were also treated with L. murinus to test its ability to activate AhR. Two defined ligands for AhR were used as controls i.e., 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD) and 6-formylindolo[3, 2-b] carbazole (FICZ). Next, we pre-treated the Caco-2 cells with either L. murinus or defined AhR ligands for 12 hours. After pre-treatment, monolayers were stimulated with TNF-alpha for 24 hours. IL-8 and TEER were quantified as endpoints to determine treatment efficacy. RESULTS: TNF-alpha stimulation decreased the TEER and induced the secretion of IL-8 in a dose-dependent manner thus, providing a model of intestinal inflammation. AhR was significantly activated in monolayers treated with L. murinus as well as with defined AhR ligands. Furthermore, pre-treating the cells with L. murinus or with endogenous AhR ligand attenuated the TNF-alpha induced pro-inflammatory response and decreased epithelial barrier disruption in Caco-2 cells. CONCLUSIONS: These results indicate that TNF-alpha induced damage to the gut wall can be attenuated using novel probiotics such L. murinus or endogenous AhR ligand. These data suggest that AhR could be a novel drug target for treating IBD. These results also indicate that L. murinus may be a potential therapeutic to mitigate or treat IBD without the use of anti-TNF-alpha agents.