Department of Medicine 1, University of Erlangen-Nuremberg, Kussmaul Campus for Medical Research, Erlangen, Germany.
Institute of Pathology, Klinikum Bayreuth, University of Erlangen-Nuremberg, Erlangen Germany.
Gastroenterology. 2021 Oct;161(4):1270-1287.e19. doi: 10.1053/j.gastro.2021.06.072. Epub 2021 Jul 3.
BACKGROUND & AIMS: The molecular checkpoints driving T cell activation and cytokine responses in ulcerative colitis (UC) are incompletely understood. Here, we studied the Tec kinase ITK in UC.
We analyzed patients with inflammatory bowel disease (n = 223) and evaluated ITK activity as well as the functional effects of cyclosporine-A (CsA). In addition, 3 independent murine colitis models were used to investigate the functional role of ITK. Finally, the activity of ITK was blocked via pharmacological inhibitors and genetically engineered mice. Readout parameters were mini-endoscopy, histopathology, mucosal T cell apoptosis, and cytokine production.
We found an expansion of pITK-expressing mucosal CD4 T cells in UC rather than Crohn's disease that correlated with disease severity. CsA suppressed activation of ITK in cultured CD4 T cells and calcineurin-containing microclusters adjacent to the T cell receptor signaling complex. Functionally, the capacity of CsA to suppress activity of experimental colitis was critically dependent on ITK. Genetic inactivation of Itk via gene targeting or induction of allele-sensitive Itk mutants prevented experimental colitis in 3 colitis models, and treatment with pharmacological ITK blockers suppressed established colitis. In addition, ITK controlled apoptosis and activation of mucosal Th2 and Th17 lymphocytes via NFATc2 signaling pathways.
ITK activation was detected in UC and could be down-regulated in cultured T cells by CsA administration. Selective targeting of ITK emerges as an attractive approach for treatment of chronic intestinal inflammation and potentially UC by driving resolution of mucosal inflammation.
溃疡性结肠炎（UC）中驱动 T 细胞激活和细胞因子反应的分子检查点尚未完全阐明。在此，我们研究了溃疡性结肠炎中的 Tec 激酶 ITK。
我们分析了炎症性肠病患者（n=223），并评估了 ITK 活性以及环孢素 A（CsA）的功能作用。此外，还使用了 3 种独立的鼠结肠炎模型来研究 ITK 的功能作用。最后，通过药理学抑制剂和基因工程小鼠来阻断 ITK 的活性。检测参数包括微型内镜、组织病理学、黏膜 T 细胞凋亡和细胞因子产生。
我们发现 UC 中存在表达 pITK 的黏膜 CD4 T 细胞扩增，而不是克罗恩病，且与疾病严重程度相关。CsA 抑制了培养的 CD4 T 细胞中 ITK 的激活以及钙调神经磷酸酶包含的微簇与 TCR 信号复合物相邻的位置。从功能上讲，CsA 抑制实验性结肠炎活性的能力严重依赖于 ITK。通过基因靶向或诱导等位基因敏感的 Itk 突变体使 Itk 基因失活，可预防 3 种结肠炎模型中的实验性结肠炎，并且使用药理学 ITK 阻滞剂可抑制已建立的结肠炎。此外，ITK 通过 NFATc2 信号通路控制黏膜 Th2 和 Th17 淋巴细胞的凋亡和激活。
在 UC 中检测到 ITK 激活，CsA 给药可在培养的 T 细胞中下调其活性。选择性靶向 ITK 通过促进黏膜炎症的消退，为慢性肠道炎症和潜在的 UC 治疗提供了一种有吸引力的方法。
