Abstract
Background and Aims Recent evidences reveal that epithelial to mesenchymal transition (EMT) exacerbates the process of intestinal fibrosis. Tumor necrosis factor-like ligand 1A (TL1A) is a member of the tumor necrosis family (TNF), which can take part in the development of colonic inflammation and fibrosis by regulating immune response or inflammatory factors. The purpose of this study was to elucidate the possible contribution of TL1A in onset and progression of intestinal inflammation and fibrosis through EMT. Methods Colonic specimens were obtained from patients with inflammatory bowel disease (IBD) and control individuals. The expression levels of TL1A and EMT-related markers in intestinal tissues were evaluated. Furthermore, the human colorectal adenocarcinoma cell line, HT-29, was stimulated with TL1A, anti-TL1A antibody, or BMP-7 to assess EMT process. In addition, transgenic mice expressing high levels of TL1A in lymphoid cells were used to further investigate the mechanism of TL1A in intestinal fibrosis. Results High levels of TL1A expression were detected in the intestinal specimens of patients with ulcerative colitis and Crohn's disease and were negatively associated with the expression of an epithelial marker (E-cadherin), while it was positively associated with the expression of interstitial markers (FSP1 and α-SMA). Transgenic mice with high expression of TL1A were more sensitive to dextran sodium sulfate and exhibited severe intestinal inflammation and fibrosis. Additionally, the TGF-β1/Smad3 pathway may be involved in TL1A-induced EMT, and the expression of IL-13 and EMT-related transcriptional molecules (e.g., ZEB1 and Snail1) was increased in the intestinal specimens of the transgenic mice. Furthermore, TL1A-induced EMT can be influenced by anti-TL1A antibody or BMP-7 in vitro. Conclusions TL1A participates in the formation and process of EMT in intestinal fibrosis. This new knowledge enables us to better understand the pathogenesis of intestinal fibrosis and identify new therapeutic targets for its treatment.
Highlights
In patients with inflammatory bowel disease (IBD), recurrent intestinal inflammation triggers mucosal healing reactions, leading to extracellular matrix (ECM) deposition in the intestine to form intestinal fibrosis [1]
Serum inflammation marker high-sensitivity C-reactive protein, erythrocyte sedimentation rate (ESR), and white blood cell (WBC) were increased in IBD patients compared with the control group (Table 2)
hematoxylin and eosin (H&E) staining revealed that the colonic mucosa was intact in the control group, while erosions and ulcers appeared in the IBD group (Figure 1(a))
Summary
In patients with inflammatory bowel disease (IBD), recurrent intestinal inflammation triggers mucosal healing reactions, leading to extracellular matrix (ECM) deposition in the intestine to form intestinal fibrosis [1]. Ulcerative colitis (UC) has long been believed to be a nonfibrotic disease; recent studies have found a certain degree of submucosal fibrosis in almost all colon resection specimens from patients with UC [5,6,7]. Transgenic mice expressing high levels of TL1A in lymphoid cells were used to further investigate the mechanism of TL1A in intestinal fibrosis. High levels of TL1A expression were detected in the intestinal specimens of patients with ulcerative colitis and Crohn’s disease and were negatively associated with the expression of an epithelial marker (E-cadherin), while it was positively associated with the expression of interstitial markers (FSP1 and α-SMA). This new knowledge enables us to better understand the pathogenesis of intestinal fibrosis and identify new therapeutic targets for its treatment
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