Interleukin-1β and Tumor Necrosis Factor-α Induce Chemokine and Matrix Metalloproteinase Gene Expression in Human Colonic Subepithelial Myofibroblasts

Abstract

Background: Colonic subepithelial myofibroblasts may play a role in the inflammatory responses and in extracellular matrix (ECM) metabolism. In this study, we investigated the effects of interleukin (IL)-1 β and tumor necrosis factor (TNF)- α on chemokine (IL-8 and monocyte chemoattractant protein (MCP)-1) and ECM turnover (proliferation of subepithelial myofibroblasts, and secretion of ECM and matrix metalloproteinases (MMPs) in colonic subepithelial myofibroblasts. Methods: Human colonic sub-epithelial myofibroblasts were isolated using the method described by Mahida et al. (4). Chemokine and MMP expressions were determined by ELISA and Northern blotting. Nuclear factor (NF)- s B and NF-IL6 DNA binding activities were evaluated by electrophoretic gel mobility shift assays (EMSA). Results: IL-1 β and TNF- α did not affect the proliferation of subepithelial myofibroblasts, but stimulated the secretion of types I and IV collagens weakly. Unstimulated subepithelial myofibroblasts secreted a large amount of MMP-2, but a small amount of IL-8, MCP-1 and MMP-1. IL-1 β and TNF- α both induced a dose- and time-dependent increase in IL-8, MCP-1 and MMP-1 secretion, and weakly stimulated MMP-2 secretion. IL-1 β and TNF- α both rapidly evoked NF- s B DNA-binding activity. The inhibition of NF- s B activation markedly blocked both IL-1 β - and TNF- α -induced IL-8 and MCP-1 mRNA expression, but did not affect MMP-1 mRNA expression. Conclusions: These observations indicate that chemokine secretion and ECM metabolism are collectively regulated by the proinflammatory cytokines, IL-1 β and TNF- α , in colonic subepithelial myofibroblasts. Thus, colonic subepithelial myofibroblasts may play an important role in the pathophysiology of inflammation in the colon.