Buoso Erica, Masi Mirco, Limosani Roberta Valeria, Fagiani Francesca, Oliviero Chiara, Colombo Giorgia, Cari Luigi, Gentili Marco, Lusenti Eleonora, Rosati Lucrezia, Pisati Federica, Pasini Alessandra, Lenti Marco Vincenzo, Di Sabatino Antonio, Mobbs Claire Louise, Przyborski Stefan, Ronchetti Simona, Travelli Cristina, Racchi Marco
Department of Drug Sciences, University of Pavia, viale Taramelli 12/14, 27100 Pavia, Italy.
Department of Pharmacology, Physiology & Biophysics, Boston University Chobanian & Avedisian School of Medicine, 700 Albany St W302 Boston, MA 02215, USA.
J Crohns Colitis. 2025 Jan 11;19(1). doi: 10.1093/ecco-jcc/jjae191.
Given the role of Receptor for Activated C Kinase 1 (RACK1) in both immune cell activation and in the maintenance of the intestinal epithelial barrier integrity, we investigated whether it was involved in inflammatory bowel disease (IBD).
RACK1 expression was analyzed in intestinal mucosal samples of healthy and IBD patients, in mice with chemically induced colitis, and in diseased in vitro 2D and 3D coculture models by luciferase assay, reverse transcription-quantitative PCR, Western blotting, immunofluorescence, and immunohistochemistry. Based on our finding that glucocorticoid-induced leucine zipper (GILZ or tsc22d3) positively correlates with RACK1 expression in IBD patients, GILZ knockout mice and cell silencing experiments were performed.
RACK1 was significantly decreased in IBD, especially in ulcerative colitis. This was associated with an NF-κB/c-Rel-related mechanism, correlating with decreased GILZ protein expression. GILZ depletion confirmed a decrease in RACK1 expression, which favored SRC activation and led to a significant reduction in E-cadherin, resulting in impaired epithelial barrier integrity. Finally, our data highlighted that this novel mechanism could be considered to develop new therapies since dexamethasone, the first line of treatment in IBD, restored RACK1 expression through the glucocorticoid receptor in a c-Rel/GILZ-independent manner.
We provide the first evidence that an alteration of RACK1/SRC/E-cadherin regulatory mechanism, correlating with decreased GILZ protein expression, is involved in epithelial barrier disruption. The clinical relevance is based on the fact that this mechanism involving GILZ/c-Rel-related RACK1 expression could be considered to improve IBD therapies, particularly in patients with low or no response to glucocorticoid treatment.
鉴于活化C激酶1受体（RACK1）在免疫细胞激活和维持肠道上皮屏障完整性方面的作用，我们研究了它是否参与炎症性肠病（IBD）。
通过荧光素酶测定、逆转录定量PCR、蛋白质免疫印迹、免疫荧光和免疫组织化学，分析健康人和IBD患者的肠道黏膜样本、化学诱导性结肠炎小鼠以及患病的体外二维和三维共培养模型中RACK1的表达。基于我们发现糖皮质激素诱导亮氨酸拉链（GILZ或tsc22d3）与IBD患者中RACK1表达呈正相关，进行了GILZ基因敲除小鼠和细胞沉默实验。
RACK1在IBD中显著降低，尤其是在溃疡性结肠炎中。这与一种NF-κB/c-Rel相关机制有关，与GILZ蛋白表达降低相关。GILZ缺失证实了RACK1表达的降低，这有利于SRC激活并导致E-钙黏蛋白显著减少，从而导致上皮屏障完整性受损。最后，我们的数据强调，这种新机制可被视为开发新疗法的依据，因为IBD的一线治疗药物地塞米松通过糖皮质激素受体以一种不依赖c-Rel/GILZ的方式恢复了RACK1的表达。
我们首次提供证据表明，RACK1/SRC/E-钙黏蛋白调节机制的改变与GILZ蛋白表达降低相关，参与了上皮屏障破坏。其临床意义在于，涉及GILZ/c-Rel相关RACK1表达的这一机制可被视为改善IBD治疗的依据，特别是对于对糖皮质激素治疗反应低或无反应的患者。
