BACKGROUND & AIMS It is not clear how regulation of T-cell function is altered during development of inflammatory bowel diseases (IBD). We studied the mechanisms by which geranylgeranyltransferase-mediated prenylation controls T-cell localization to the intestine and chronic inflammation. METHODS We generated mice with T-cell-specific disruption of the geranylgeranyltransferase type I, beta subunit gene (Pggt1b), called Pggt1bΔCD4 mice, or the ras homolog family member A gene (Rhoa), called RhoaΔCD4 mice. We also studied mice with knockout of CDC42 or RAC1 and wild-type mice (controls). Intestinal tissues were analyzed by histology, multiphoton and confocal microscopy, and real-time polymerase chain reaction. Activation of CDC42, RAC1, and RHOA were measured with G-LISA, cell fractionation, and immunoblots. T cells and lamina propria mononuclear cells from mice were analyzed by flow cytometry or transferred to Rag1-/- mice. Mice were given injections of antibodies against integrin alpha4beta7 or gavaged with the RORC antagonist GSK805. We obtained peripheral blood and intestinal tissue samples from patients with and without IBD and analyzed them by flow cytometry. RESULTS Pggt1bΔCD4 mice developed spontaneous colitis, characterized by thickening of the intestinal wall, edema, fibrosis, accumulation of T cells in the colon, and increased expression of inflammatory cytokines. Compared with control CD4+ T cells, PGGT1B-deficient CD4+ T cells expressed significantly higher levels of integrin alpha4beta7, which regulates their localization to the intestine. Inflammation induced by transfer of PGGT1B-deficient CD4+ T cells to Rag1-/- mice was blocked by injection of an antibody against integrin alpha4beta7. Lamina propria of Pggt1bΔCD4 mice had increased numbers of CD4+ T cells that expressed RORC and higher levels of cytokines produced by T-helper 17 cells (granulocyte-macrophage colony-stimulating factor, interleukin [IL]17A, IL17F, IL22, and tumor necrosis factor [TNF]). The RORC inverse agonist GSK805, but not antibodies against IL17A or IL17F, prevented colitis in Pggt1bΔCD4 mice. PGGT1B-deficient CD4+ T cells had decreased activation of RHOA. RhoAΔCD4 mice had a similar phenotype to Pggt1bΔCD4 mice, including development of colitis, increased numbers of CD4+ T cells in colon, increased expression of integrin alpha4beta7 by CD4+ T cells, and increased levels of IL17A and other inflammatory cytokines in lamina propria. T cells isolated from intestinal tissues from patients with IBD had significantly lower levels of PGGT1B than tissues from individuals without IBD. CONCLUSION Loss of PGGT1B from T cells in mice impairs RHOA function, increasing CD4+ T-cell expression of integrin alpha4beta7 and localization to colon, resulting in increased expression of inflammatory cytokines and colitis. T cells isolated from gut tissues from patients with IBD have lower levels of PGGT1B than tissues from patients without IBD.

中文翻译：

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抑制PGGT1B破坏RHOA的功能，导致整联蛋白α4β7的T细胞表达和小鼠结肠炎的发展。

背景与目的目前尚不清楚在炎症性肠病（IBD）发生过程中如何改变T细胞功能的调节。我们研究了香叶基香叶基转移酶介导的烯丙基化作用控制小肠和慢性炎症T细胞定位的机制。方法我们生成了具有T细胞特异性I型香叶基香叶基转移酶，β亚基基因（Pggt1b），称为Pggt1bΔCD4小鼠或ras同源家族成员A基因（Rhoa），称为RhoaΔCD4小鼠的小鼠。我们还研究了敲除CDC42或RAC1的小鼠和野生型小鼠（对照）。通过组织学，多光子和共聚焦显微镜以及实时聚合酶链反应分析肠道组织。CDC42，RAC1和RHOA的激活用G-LISA，细胞分级分离和免疫印迹进行了测量。通过流式细胞术分析来自小鼠的T细胞和固有层单核细胞，或将其转移至Rag1-/-小鼠。给小鼠注射针对整联蛋白α4β7的抗体或用RORC拮抗剂GSK805管控。我们从有和没有IBD的患者那里获取了外周血和肠组织样本，并通过流式细胞仪对其进行了分析。结果Pggt1bΔCD4小鼠发展为自发性结肠炎，其特征是肠壁增厚，水肿，纤维化，结肠中T细胞积聚和炎性细胞因子的表达增加。与对照CD4 + T细胞相比，PGGT1B缺陷型CD4 + T细胞表达的整合素alpha4beta7水平明显更高，这调节了它们在肠道中的定位。PGGT1B缺陷型CD4 + T细胞转移至Rag1-/-小鼠引起的炎症通过注射针对整联蛋白alpha4beta7的抗体来阻断。Pggt1bΔCD4小鼠的固有层具有表达RORC的CD4 + T细胞数量增加，以及由T辅助17细胞（粒细胞-巨噬细胞集落刺激因子，白介素[IL] 17A，IL17F，IL22和肿瘤坏死因子）产生的细胞因子水平更高[TNF]）。RORC反向激动剂GSK805预防了Pggt1bΔCD4小鼠的结肠炎，但没有针对IL17A或IL17F的抗体。PGGT1B缺陷型CD4 + T细胞的RHOA激活降低。RhoAΔCD4小鼠的表型与Pggt1bΔCD4小鼠相似，包括结肠炎的发展，结肠中CD4 + T细胞数量的增加，CD4 + T细胞中整联蛋白alpha4beta7的表达增加，固有层中IL17A和其他炎性细胞因子的水平升高。从IBD患者的肠组织中分离的T细胞的PGGT1B水平显着低于无IBD患者的组织。结论小鼠T细胞中PGGT1B的缺失损害了RHOA功能，增加了整联蛋白alpha4beta7的CD4 + T细胞表达并定位于结肠，导致炎症性细胞因子和结肠炎的表达增加。从IBD患者的肠组织中分离出的T细胞的PGGT1B含量低于未IBD患者的组织。整合素alpha4beta7的CD4 + T细胞表达增加，并定位到结肠，导致炎症性细胞因子和结肠炎的表达增加。从IBD患者的肠组织中分离出的T细胞的PGGT1B含量低于未IBD患者的组织。整合素alpha4beta7的CD4 + T细胞表达增加，并定位到结肠，导致炎症性细胞因子和结肠炎的表达增加。从IBD患者的肠组织中分离出的T细胞的PGGT1B含量低于未IBD患者的组织。