Blair Stephanie A, Kane Sunanda V, Clayburgh Daniel R, Turner Jerrold R
Department of Pathology, The University of Chicago, Chicago, IL 60637, USA.
Lab Invest. 2006 Feb;86(2):191-201. doi: 10.1038/labinvest.3700373.
The intestinal epithelial barrier is frequently disrupted in inflammatory bowel disease (IBD) and this has been proposed to play a role in disease pathogenesis and reactivation. In vitro studies show that cytokine-induced epithelial barrier dysfunction can be mediated by increased myosin light chain kinase (MLCK) expression and subsequent myosin II regulatory light chain (MLC) phosphorylation. However, this has never been examined in human disease. The aim of these studies, therefore, was to determine whether MLCK is upregulated in the intestinal epithelium of IBD patients. MLCK expression and MLC phosphorylation in human intestinal resection and biopsy specimens were determined by quantitative immunofluorescence microscopy and correlated with clinical and histopathological data. The data show that ileal epithelial MLCK expression was mildly upregulated in inactive IBD. Expression increased further in active disease, with progressive increases in MLCK expression correlating positively with histological disease activity. This correlation between activity and MLCK expression was also seen in individual patients where areas of differing disease activity were analyzed. Colonic epithelial MLCK expression was similarly increased in active IBD and these increases also correlated positively with disease activity, both in individual patients and the overall study group. To evaluate MLCK enzymatic activity, MLC phosphorylation was assessed in snap-frozen colon biopsies. MLC phosphorylation was significantly increased in biopsies with active, but not inactive, IBD. Therefore, these data show that MLCK expression and enzymatic activity are increased in IBD. Moreover, the correlation with disease activity suggests that MLCK upregulation may contribute to barrier dysfunction and IBD pathogenesis.
肠道上皮屏障在炎症性肠病（IBD）中常被破坏，这被认为在疾病发病机制和复发中起作用。体外研究表明，细胞因子诱导的上皮屏障功能障碍可由肌球蛋白轻链激酶（MLCK）表达增加及随后的肌球蛋白II调节轻链（MLC）磷酸化介导。然而，这从未在人类疾病中得到验证。因此，这些研究的目的是确定IBD患者肠道上皮中MLCK是否上调。通过定量免疫荧光显微镜测定人肠道切除和活检标本中的MLCK表达及MLC磷酸化，并将其与临床和组织病理学数据相关联。数据显示，在非活动性IBD中，回肠上皮MLCK表达轻度上调。在活动性疾病中表达进一步增加，MLCK表达的逐渐增加与组织学疾病活动呈正相关。在分析了不同疾病活动区域的个体患者中也观察到了活动与MLCK表达之间的这种相关性。在活动性IBD中，结肠上皮MLCK表达同样增加，并且在个体患者和整个研究组中，这些增加也与疾病活动呈正相关。为了评估MLCK酶活性，在速冻结肠活检中评估MLC磷酸化。在活动性而非非活动性IBD的活检中，MLC磷酸化显著增加。因此，这些数据表明IBD中MLCK表达和酶活性增加。此外，与疾病活动的相关性表明MLCK上调可能导致屏障功能障碍和IBD发病机制。
