Aryl hydrocarbon receptor activation by TCDD reduces inflammation associated with Crohn's disease.
Crohn's disease results from a combination of genetic and environmental factors that trigger an inappropriate immune response to commensal gut bacteria. The aryl hydrocarbon receptor (AhR) is well known for its involvement in the toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), an environmental contaminant that affects people primarily through the diet. Recently, TCDD was shown to suppress immune responses by generating regulatory T cells (Tregs). We hypothesized that AhR activation dampens inflammation associated with Crohn's disease. To test this hypothesis, we utilized the 2,4,6-trinitrobenzenesulfonic acid (TNBS) murine model of colitis. Mice were gavaged with TCDD prior to colitis induction with TNBS. Several parameters were examined including colonic inflammation via histological and flow cytometric analyses. TCDD-treated mice recovered body weight faster and experienced significantly less colonic damage. Reduced levels of interleukin (IL) 6, IL-12, interferon-gamma, and tumor necrosis factor-α demonstrated suppression of inflammation in the gut following TCDD exposure. Forkhead box P3 (Foxp3)(egfp) mice revealed that TCDD increased the Foxp3+ Treg population in gut immune tissue following TNBS exposure. Collectively, these results suggest that activation of the AhR by TCDD decreases colonic inflammation in a murine model of colitis in part by generating regulatory immune cells. Ultimately, this work may lead to the development of more effective therapeutics for the treatment of Crohn's disease.
Department of Biomedical and Pharmaceutical Sciences, Center for Environmental Health Sciences, University of Montana, Missoula, Montana 59812, USA.
Jenna M
JM
Benson
David M
DM
Shepherd
D000818:Animals; D003092:Colitis / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D003106:Colon / Q000187:drug effects / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D003424:Crohn Disease / Q000276:immunology / Q000378:metabolism* / Q000473:pathology; D016207:Cytokines / Q000276:immunology; D004195:Disease Models, Animal; D005260:Female; D005434:Flow Cytometry; D051858:Forkhead Transcription Factors / Q000235:genetics; D007150:Immunohistochemistry; D008198:Lymph Nodes / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D000072317:Polychlorinated Dibenzodioxins / Q000494:pharmacology*; D018336:Receptors, Aryl Hydrocarbon / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D050378:T-Lymphocytes, Regulatory / Q000187:drug effects / Q000276:immunology
D016207:Cytokines; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D000072317:Polychlorinated Dibenzodioxins; D018336:Receptors, Aryl Hydrocarbon