Downregulation of CPI-17 contributes to dysfunctional motility in chronic intestinal inflammation model mice and ulcerative colitis patients
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Chronic intestinal inflammation is frequently accompanied by motility disorders. We previously reported that proinflammatory cytokines, such as tumor necrosis factor α and interleukin (IL)-1β downregulate CPI-17, an endogenous inhibitor of serine/threonine protein phosphatase in smooth-muscle cells, which results in the inhibition of myosin light chain phosphorylation and contractility. However, its clinical relevance has not been clarified.
The present study examined the changes in CPI-17 expression in chronic intestinal inflammation using smooth-muscle tissues from IL-10 knockout mice and from patients with ulcerative colitis (UC).
The IL-10 knockout mice developed spontaneous and chronic colitis accompanied by immune cell infiltration, submucosal fibrosis, and thickening of the muscularis externa. The expression of α-smooth muscle actin protein in the smooth-muscle layer did not change, whereas that of CPI-17 protein was decreased by about 40% compared with healthy wild-type controls. Consistent with this observation, smooth-muscle contractile force and myosin light chain phosphorylation induced by a muscarinic agonist were reduced in the knockout mice. Moreover, we observed that CPI-17 protein expression was decreased in smooth-muscle tissues from patients with UC compared with controls.
CPI-17 downregulation might contribute to the decreased motor function in chronic inflammatory bowel diseases.
Key wordsCPI-17 IL-10 colitis ulcerative colitis contraction
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