Mouse Model Of Intestinal Fibrosis Research Articles

Caveolin-1 Alleviates Crohn's Disease-induced Intestinal Fibrosis by Inhibiting Fibroblasts Autophagy Through Modulating Sequestosome 1.

Intestinal fibrosis is a common complication of Crohn's disease (CD) and is characterized by the excessive accumulation of extracellular matrix produced by activated myofibroblasts. Caveolin-1 (CAV1) inhibits fibrosis. However, limited data show that CAV1 affects intestinal fibrosis. Human CD tissue samples were gained from patients with CD who underwent surgical resection of the intestine and were defined as stenotic or nonstenotic areas. A dextran sodium sulfate-induced mouse model of intestinal fibrosis was established. For in vitro experiments, we purchased CCD-18Co intestinal fibrosis cells and isolated and cultured human primary colonic fibroblasts. These fibroblasts were activated by transforming growth factor β administration for 48 hours. In the functional experiments, a specific small interfering RNA or overexpression plasmid was transfected into fibroblasts. The messenger RNA levels of fibrosis markers, such as α-smooth muscle actin, fibronectin, connective tissue growth factor, and collagen I1α, were determined using quantitative polymerase chain reaction. Western blot analysis was applied to detect the expression of CAV1, SQSTM1/p62 (sequestosome 1), and other fibrosis markers. In human CD samples and the dextran sodium sulfate-induced mouse model of intestinal fibrosis, we observed a downregulation of CAV1 in fibrosis-activated areas. Mechanistically, CAV1 knockdown in both human primary colonic fibroblasts and CCD-18Co cells promoted fibroblast activation, while CAV1 overexpression inhibited fibroblast activation in vitro. We found that SQSTM1/p62 positively correlated with CAV1 expression levels in patients with CD and that it was indirectly modulated by CAV1 expression. Rescue experiments showed that CAV1 decreased primary human intestinal fibroblast activation by inhibiting fibroblast autophagy through the modulation of SQSTM1/p62. Our data demonstrate that CAV1 deficiency induces fibroblast activation by indirectly regulating SQSTM1/p62 to promote fibroblast autophagy. CAV1 or SQSTM1/p62 may be potential therapeutic targets for intestinal fibrosis.

P013 Decreased fibrogenesis in CH25H knockout mice in a mouse model of intestinal fibrosis

P013 Decreased fibrogenesis in CH25H knockout mice in a mouse model of intestinal fibrosis

Su1871 Decreased Fibrogenesis in CH25H−/− Mice in a Newly Developed Mouse Model of Intestinal Fibrosis

Su1871 Decreased Fibrogenesis in CH25H−/− Mice in a Newly Developed Mouse Model of Intestinal Fibrosis

Decreased Fibrogenesis After Treatment with Pirfenidone in a Newly Developed Mouse Model of Intestinal Fibrosis

Fibrosis as a common problem in patients with Crohn's disease is a result of an imbalance toward excessive tissue repair. At present, there is no specific treatment option. Pirfenidone is approved for the treatment of idiopathic pulmonary fibrosis with both antifibrotic and anti-inflammatory effects. We subsequently investigated the impact of pirfenidone treatment on development of fibrosis in a new mouse model of intestinal fibrosis. Small bowel resections from donor mice were transplanted subcutaneously into the neck of recipients. Animals received either pirfenidone (100 mg/kg, three times daily, orally) or vehicle. After administration of pirfenidone, a significantly decreased collagen layer thickness was revealed as compared to vehicle (9.7 ± 1.0 versus 13.5 ± 1.5 µm, respectively, **P < 0.001). Transforming growth factor-β and matrix metalloproteinase-9 were significantly decreased after treatment with pirfenidone as confirmed by real-time PCR (0.42 ± 0.13 versus 1.00 ± 0.21 and 0.46 ± 0.24 versus 1.00 ± 0.62 mRNA expression level relative to GAPDH, respectively, *P < 0.05). Significantly decreased transforming growth factor-β after administration of pirfenidone was confirmed by Western blotting. In our mouse model, intestinal fibrosis can be reliably induced and is developed within 7 days. Pirfenidone partially prevented the development of fibrosis, making it a potential treatment option against Crohn's disease-associated fibrosis.

Epithelial-to-Mesenchimal Transition (EMT) in experimental intestinal fibrosis

Inflammatory Bowel Diseases (IBD) are chronic and progressive inflammatory disorders that may result in intestinal fibrosis, characterized by excessive and uncon- trolled deposition of extracellular matrix components (ECM). Other than Smad- dependent the profibrotic effects of TGFβ signaling that leads to a phenotype switch of intestinal mesenchymal cells, resulting in proliferation and collagene deposition (1), source of fibrotic tissue comes from the process called Epithelial-to-Mesenchymal Transition (EMT), in which also epithelial cells acquire fibroblastic phenotype and related function (2). The purpose of our study was to evaluate the expression of pro- tein markers of EMT in a mouse model of intestinal fibrosis and their changes after the administration of the experimental drug GED- 0507-34 Levo, that is able to inhibit and revert the fibrotic phenotypic switch. Immunohistochemistry (IHC) and immunofluorescence (IF) evalutations for E-cadherin and β-catenin were performed in three groups of C57BL/6 mice: Dextran Sulphate Sodium (DSS) colitis group, DSS+GED group and controls. In the same groups E-cadherin, β-catenin, p-GSK3-beta and GSK3-beta were evaluated by immunoblotting. In IHC and IF analysis, was observed a significant decrease of E-cadherin and β-catenin expression in DSS group compared to control. GED administration was able to revert the DSS effect by increasing the expression of both proteins to levels similar to the control. Comparable results were obtained by immunoblotting. Furthermore the immunoblotting assay showed that the known EMT inhibitor GSK3-beta is activated in the DSS+GED group suggesting that GSK3-beta activity is required for the restoration of the epithelial phenotype exerted by GED. Taken together, our results indicates that the EMT is another cause of colla- gen deposition in our mouse model and thus it could be a valid target for the devel- opment of a treatment for intestinal fibrosis.

Mo1822 Regional Differences in the Early Onset of Fibrosis in an Ex Vivo Mouse Model of Intestinal Fibrosis

Mo1822 Regional Differences in the Early Onset of Fibrosis in an Ex Vivo Mouse Model of Intestinal Fibrosis

Irsogladine maleate ameliorates inflammation and fibrosis in mice with chronic colitis induced by dextran sulfate sodium

Intestinal fibrosis is a common and severe complication of inflammatory bowel disease (IBD), especially Crohn's disease (CD). To investigate the therapeutic approach to intestinal fibrosis, we have developed a mouse model of intestinal fibrosis by administering dextran sulfate sodium (DSS) and examining the effects of irsogladine maleate (IM) [2,4-diamino-6-(2,5-dichlorophenyl)-s-triazine maleate], which has been widely used as an antiulcer drug for gastric mucosa in Japan, on DDS-induced chronic colitis. In this experimental colitis lesion, several pathognomonic changes were found: increased deposition of collagen, increased number of profibrogenic mesenchymal cells such as fibroblasts (vimentin(+), α-SMA(-)) and myofibroblasts (vimentin(+), α-SMA(+)) in both mucosa and submucosa of the colon with infiltrating inflammatory cells, and increased mRNA expressions of collagen type I, transforming growth factor (TGF)-β, matrix metalloproteinase (MMP)-2, and tissue inhibitor of matrix metalloproteinase (TIMP)-1. When IM was administered intrarectally to this colitis, all these pathological changes were significantly decreased or suppressed, suggesting a potential adjunctive therapy for intestinal fibrosis. IM could consequently reduce fibrosis in DSS colitis by direct or indirect effect on profibrogenic factors or fibroblasts. Therefore, the precise effect of IM on intestinal fibrosis should be investigated further.

Intestinal fibrosis is reduced by early elimination of inflammation in a mouse model of IBD: Impact of a “Top-Down” approach to intestinal fibrosis in mice

The natural history of Crohn's disease follows a path of progression from an inflammatory to a fibrostenosing disease, with most patients requiring surgical resection of fibrotic strictures. Potent antiinflammatory therapies reduce inflammation but do not appear to alter the natural history of intestinal fibrosis. The aim of this study was to determine the relationship between intestinal inflammation and fibrogenesis and the impact of a very early "top-down" interventional approach on fibrosis in vivo. In this study we removed the inflammatory stimulus from the Salmonella typhimurium mouse model of intestinal fibrosis by eradicating the S. typhimurium infection with levofloxacin at sequential timepoints during the infection. We evaluated the effect of this elimination of the inflammatory stimulus on the natural history of inflammation and fibrosis as determined by gross pathology, histopathology, mRNA expression, and protein expression. Fibrogenesis is preceded by inflammation. Delayed eradication of the inflammatory stimulus by antibiotic treatment represses inflammation without preventing fibrosis. Early intervention significantly ameliorates but does not completely prevent subsequent fibrosis. This study demonstrates that intestinal fibrosis develops despite removal of an inflammatory stimulus and elimination of inflammation. Early intervention ameliorates but does not abolish subsequent fibrosis, suggesting that fibrosis, once initiated, is self-propagating, suggesting that a very early top-down interventional approach may have the most impact on fibrostenosing disease.

TGF-β1 gene transfer to the mouse colon leads to intestinal fibrosis

Crohn's disease (CD) is a chronic, relapsing inflammatory bowel disease, characterized by transmural inflammation. In CD, the recurrent inflammatory injury and tissue repair that occurs in the intestine can progress uncontrollably, leading to the proliferation of mesenchymal cells as well as fibrosis, characterized by excessive extracellular matrix deposition. These processes thicken the bowel wall, reducing flexibility, and often culminate in obstructive strictures. Because no effective measures are currently available to specifically treat or prevent intestinal stricturing, we sought to gain a better understanding of its pathogenesis by developing a mouse model of intestinal fibrosis. Because transforming growth factor (TGF)-beta1 can mediate both fibrosis and mesenchymal cell proliferation; we studied the effects of delivering adenoviral vectors encoding spontaneously active TGF-beta1 into the colons of mice. We first demonstrated that enema delivery of marker adenoviral vectors led to the transfection of the colonic epithelium and transient transgene expression. Histologically, control vectors caused an acute inflammatory response, involving the recruitment of neutrophils and mononuclear cells into the colonic lamina propria; however, infection caused little if any fibrosis. In contrast, the TGF-beta1 vector caused a more severe and prolonged inflammatory response as well as localized collagen deposition, leading to severe and progressive fibrosis. This was accompanied by the emergence of cells with a myofibroblast phenotype. Ultimately the fibrosis resulted in many of the TGF-beta1-transfected mice developing profound colonic obstruction. Through adenoviral gene transfer technology, we describe a novel mouse model of colitis and implicate TGF-beta1 in the pathogenesis of obstructive intestinal fibrosis.