Vivek Krishna Pulakazhi Venu1,2, Laurie Alston1,2, Mircea C Iftinca1,2, Yi-Cheng Tsai1,2, Matthew Stephens1,2, Vineetha Warriyar3, Sonia Rehal4, Grace Marie Hudson1,2, Holly Szczepanski1,2, Pierre-Yves von der Weid1,2, Christophe Altier1,2,5, Simon A Hirota1,6,2,5. 1. Department of Physiology and Pharmacology, University of Calgary, Calgary, AB, Canada. 2. Snyder Institute for Chronic Disease, University of Calgary, Calgary, AB, Canada. 3. SIPRC, Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada. 4. University Health Network, Department of Advanced Diagnostics, Toronto, Ontario, Canada. 5. Alberta Children's Hospital Research Institute, University of Calgary, Calgary, AB, Canada. 6. Department of Immunology, Microbiology and Infectious Diseases, University of Calgary, Calgary, AB, Canada.
Abstract
BACKGROUND: Intestinal fibrosis is a common complication of the inflammatory bowel diseases(IBD), contributing to tissue stiffening and luminal narrowing. NR4A1 was previously reported to regulate mesenchymal cell function and dampen fibrogenic signaling. NR4A1 gene variants are associated with IBD risk, and it has been shown to regulate intestinal inflammation. Here, we tested the hypothesis that NR4A1 acts as a negative regulator of intestinal fibrosis through regulating myofibroblast function. METHODS: Using the SAMP1/YitFc mouse, we tested whether two pharmacological agents known to enhance NR4A1 signaling: cytosporone B(Csn-B) or 6-mercaptopurine(6-MP); could reduce fibrosis. We also employed the dextran sulphate sodium(DSS) model of colitis and assessed the magnitude of colonic fibrosis in Nr4a1-/- and their wild-type littermates(Nr4a1+/+). Lastly, intestinal myofibroblasts isolated from Nr4a1-/- and Nr4a1+/+ mice or primary human intestinal myofibroblasts were stimulated with transforming growth factor-beta-1(TGF-β1), in the presence or absence of Csn-B or 6-MP, and proliferation and ECM gene expression assessed. RESULTS: Csn-B or 6-MP treatment significantly reduced ileal thickness, collagen and overall ECM content in SAMP1/YitFc mice. This was associated with a reduction in proliferative markers within the mesenchymal compartment. Nr4a1-/- mice exposed to DSS exhibited increased colonic thickening and ECM content. Nr4a1-/- myofibroblasts displayed enhanced TGF-β1-induced proliferation. Furthermore, Csn-B or 6-MP treatment was anti-proliferative in Nr4a1+/+, but not Nr4a1-/- cells. Lastly, activating NR4A1 in human myofibroblasts reduced TGF-β1-induced collagen deposition and fibrosis-related gene expression. CONCLUSIONS: Our data suggest that NR4A1 can attenuate fibrotic processes in intestinal myofibroblasts and could provide a valuable clinical target to treat inflammation-associated intestinal fibrosis.
BACKGROUND: Intestinal fibrosis is a common complication of the inflammatory bowel diseases(IBD), contributing to tissue stiffening and luminal narrowing. NR4A1 was previously reported to regulate mesenchymal cell function and dampen fibrogenic signaling. NR4A1 gene variants are associated with IBD risk, and it has been shown to regulate intestinal inflammation. Here, we tested the hypothesis that NR4A1 acts as a negative regulator of intestinal fibrosis through regulating myofibroblast function. METHODS: Using the SAMP1/YitFc mouse, we tested whether two pharmacological agents known to enhance NR4A1 signaling: cytosporone B(Csn-B) or 6-mercaptopurine(6-MP); could reduce fibrosis. We also employed the dextran sulphate sodium(DSS) model of colitis and assessed the magnitude of colonic fibrosis in Nr4a1-/- and their wild-type littermates(Nr4a1+/+). Lastly, intestinal myofibroblasts isolated from Nr4a1-/- and Nr4a1+/+ mice or primary human intestinal myofibroblasts were stimulated with transforming growth factor-beta-1(TGF-β1), in the presence or absence of Csn-B or 6-MP, and proliferation and ECM gene expression assessed. RESULTS:Csn-B or 6-MP treatment significantly reduced ileal thickness, collagen and overall ECM content in SAMP1/YitFc mice. This was associated with a reduction in proliferative markers within the mesenchymal compartment. Nr4a1-/- mice exposed to DSS exhibited increased colonic thickening and ECM content. Nr4a1-/- myofibroblasts displayed enhanced TGF-β1-induced proliferation. Furthermore, Csn-B or 6-MP treatment was anti-proliferative in Nr4a1+/+, but not Nr4a1-/- cells. Lastly, activating NR4A1 in human myofibroblasts reduced TGF-β1-induced collagen deposition and fibrosis-related gene expression. CONCLUSIONS: Our data suggest that NR4A1 can attenuate fibrotic processes in intestinal myofibroblasts and could provide a valuable clinical target to treat inflammation-associated intestinal fibrosis.
Authors: Shijie He; Dara A Azar; Farid Nasr Esfahani; Golara A Azar; Tarek Shazly; Nima Saeidi Journal: Inflamm Bowel Dis Date: 2022-08-01 Impact factor: 7.290