Department of Radiobiology and Human Health, ENEA, Rome, Italy.
Pattern Recognition Receptor Discovery Performance Unit, GlaxoSmithKline, Collegeville, Pennsylvania, USA.
Am J Gastroenterol. 2014 Feb;109(2):279-87. doi: 10.1038/ajg.2013.403. Epub 2013 Dec 10.
A new caspase-independent mode of programmed cell death, termed necroptosis, has recently been identified. Altered expression of molecules involved in the necroptosis pathway has been shown to trigger intestinal inflammation. The initiation of necroptosis is principally mediated by the release of receptor interacting protein 3 (RIP3) from suppression by caspase-8. Furthermore, it has been suggested that the mixed lineage kinase domain-like (MLKL) factor is an interacting target of RIP3 in active necroptosis. This study aims at investigating the occurrence of necroptosis in children with inflammatory bowel disease (IBD) and its contribution to human intestinal inflammation.
Biopsy samples were collected from the ileum and colon of 33 children with Crohn's disease, 30 with ulcerative colitis, and 20 healthy controls. Ten children with allergic colitis (AC) were used as non-IBD comparators. RIP3, caspase-8, and MLKL protein expression levels were evaluated by western blotting. The adenocarcinoma cell line HT29 was used for in vitro experiments.
RIP3 and MLKL increased (P<0.01) in inflamed tissues of IBD and AC patients, whereas caspase-8 was reduced. No variations were observed in uninflamed tissues of patients. The relationship between RIP3 increase, active necroptosis, and intestinal inflammation was confirmed by in vitro analyses.
We show for the first time that necroptosis is strongly associated with intestinal inflammation in children with IBD and contributes to strengthen the inflammatory process. We believe that RIP3 and MLKL could represent attractive targets for the management of human IBD.
最近发现了一种新的细胞程序性死亡方式，称为坏死性凋亡。已证实参与坏死性凋亡途径的分子表达的改变会引发肠道炎症。坏死性凋亡的启动主要是通过受体相互作用蛋白 3（RIP3）从 caspase-8 的抑制中释放来介导的。此外，有人提出混合谱系激酶结构域样（MLKL）因子是活性坏死性凋亡中 RIP3 的相互作用靶标。本研究旨在研究坏死性凋亡在儿童炎症性肠病（IBD）中的发生及其对人类肠道炎症的贡献。
收集 33 例克罗恩病、30 例溃疡性结肠炎和 20 例健康对照儿童的回肠和结肠活检标本。10 例过敏性结肠炎（AC）患儿作为非 IBD 对照组。采用 Western blot 法检测 RIP3、caspase-8 和 MLKL 蛋白表达水平。采用人结肠癌细胞系 HT29 进行体外实验。
IBD 和 AC 患者炎症组织中 RIP3 和 MLKL 增加（P<0.01），而 caspase-8 减少。患者非炎症组织中未观察到变化。体外分析证实了 RIP3 增加、活性坏死性凋亡与肠道炎症之间的关系。
我们首次表明，坏死性凋亡与儿童 IBD 患者的肠道炎症密切相关，并有助于增强炎症过程。我们认为 RIP3 和 MLKL 可能成为人类 IBD 治疗的有吸引力的靶点。
