Keshavarzian A, Banan A, Farhadi A, Komanduri S, Mutlu E, Zhang Y, Fields J Z
Department of Internal Medicine (Division of Digestive Diseases), Pharmacology, and Molecular Physiology, Rush University Medical Center, Chicago, IL 60612, USA.
Gut. 2003 May;52(5):720-8. doi: 10.1136/gut.52.5.720.
Overproduction of colonic oxidants contributes to mucosal injury in inflammatory bowel disease (IBD) but the mechanisms are unclear. Our recent findings using monolayers of intestinal cells suggest that the mechanism could be oxidant induced damage to cytoskeletal proteins. However, oxidants and oxidative damage have not been well characterised in IBD mucosa.
To determine whether there are increases in oxidants and in tissue and cytoskeletal protein oxidation in IBD mucosa.
We measured nitric oxide (NO) and markers of oxidative injury (carbonylation and nitrotyrosination) to tissue and cytoskeletal proteins in colonic mucosa from IBD patients (ulcerative colitis, Crohn's disease, specific colitis) and controls. Outcomes were correlated with IBD severity score.
Inflamed mucosa showed the greatest increases in oxidants and oxidative damage. Smaller but still significant increases were seen in normal appearing mucosa of patients with active and inactive IBD. Tissue NO levels correlated with oxidative damage. Actin was markedly (>50%) carbonylated and nitrated in inflamed tissues of active IBD, less so in normal appearing tissues. Tubulin carbonylation occurred in parallel; tubulin nitration was not observed. NO and all measures of oxidative damage in tissue and cytoskeletal proteins in the mucosa correlated with IBD severity. Disruption of the actin cytoarchitecture was primarily within the epithelial cells and paracellular area.
Oxidant levels increase in IBD along with oxidation of tissue and cytoskeletal proteins. Oxidative injury correlated with disease severity but is also present in substantial amounts in normal appearing mucosa of IBD patients, suggesting that oxidative injury does not necessarily lead to tissue injury and is not entirely a consequence of tissue injury. Marked actin oxidation (>50%)-which appears to result from cumulative oxidative damage-was only seen in inflamed mucosa, suggesting that oxidant induced cytoskeletal disruption is required for tissue injury, mucosal disruption, and IBD flare up.
结肠氧化剂的过度产生会导致炎症性肠病(IBD)的黏膜损伤,但具体机制尚不清楚。我们最近利用肠道细胞单层进行的研究结果表明,其机制可能是氧化剂诱导的细胞骨架蛋白损伤。然而,IBD黏膜中的氧化剂和氧化损伤尚未得到充分表征。
确定IBD黏膜中氧化剂、组织及细胞骨架蛋白氧化是否增加。
我们测量了IBD患者(溃疡性结肠炎、克罗恩病、特异性结肠炎)和对照组结肠黏膜中一氧化氮(NO)以及组织和细胞骨架蛋白氧化损伤标志物(羰基化和硝基化)。结果与IBD严重程度评分相关。
发炎的黏膜中氧化剂和氧化损伤增加最为显著。在活动期和非活动期IBD患者外观正常的黏膜中也有较小但仍显著的增加。组织NO水平与氧化损伤相关。在活动期IBD的发炎组织中,肌动蛋白明显(>50%)发生羰基化和硝基化,在外观正常的组织中则较少。微管蛋白羰基化与之平行发生;未观察到微管蛋白硝基化。黏膜中组织和细胞骨架蛋白的NO及所有氧化损伤指标与IBD严重程度相关。肌动蛋白细胞结构的破坏主要发生在上皮细胞和细胞旁区域。
IBD中氧化剂水平升高,同时伴有组织和细胞骨架蛋白的氧化。氧化损伤与疾病严重程度相关,但在IBD患者外观正常的黏膜中也大量存在,这表明氧化损伤不一定会导致组织损伤,也不完全是组织损伤的结果。明显的肌动蛋白氧化(>50%)——似乎是累积氧化损伤的结果——仅在发炎的黏膜中可见,这表明氧化剂诱导的细胞骨架破坏是组织损伤、黏膜破坏和IBD发作所必需的。