Department of Gastroenterology, Longhua Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
Department of Rheumatology, Yueyang Hospital of Integrated Traditional Chinese and Western Medicine, Shanghai University of Traditional Chinese Medicine, Shanghai, China.
Front Immunol. 2024 Sep 12;15:1425363. doi: 10.3389/fimmu.2024.1425363. eCollection 2024.
There is already substantial evidence indicating that neutrophil extracellular trap (NET) formation contributes to the inflammatory cascade in ulcerative colitis (UC). However, the precise regulatory mechanisms governing this process remain elusive. This study aimed to determine the role of NET-related genes in UC and reveal possible mechanisms.
Employing a two-sample MR methodology, we investigated the correlations between NET-associated genes (NRGs) and UC with summary data derived from a genome-wide association study (12,366 cases vs. 33,609 controls) and FinnGen (8,279 cases vs. 261,098 controls). The main analysis employed the inverse variance weighted method, supplemented by the MR-Egger method and weighted median method. Sensitivity analysis was conducted to rule out the interference of heterogeneity and pleiotropy among utilized instrument variables. The colocalization analysis was used to determine whether the identified NRGs and UC shared casual variants. Cross-tissue expression analysis was performed to characterize the expression patterns of target NRGs, while multi-gene correlation analysis and GSEA analysis were conducted to explore the mechanisms by which target NRGs promote UC and NET formation. Immunohistochemistry was used to validate the protein expression of target NRGs in the colon tissue of UC patients.
After the validation of two datasets, seven NRGs were associated with the risk of UC. The higher expression of ITGB2 was associated with increased UC risk, while the expression of CXCR1, CXCR2, IRAK4, MAPK3, SIGLEC14, and SLC22A4 were inversely associated with UC risk. Colocalization analysis supported the correlation between CXCR1/2 and UC risk. Expression analysis indicated that CXCR1/2 were down-regulated in peripheral blood, but up-regulated in colon tissue. GSEA analysis and correlation analysis indicated that CXCR1/2 promoted UC and NET formation through neutrophil chemotaxis and PAD4-mediated pathways, separately. Immunohistochemical results confirmed the high expression of CXCR1/2 in colon tissues of UC patients.
Our study identified CXCR1/2 as candidate targets in UC among all NRGs through multi-method argumentation, providing new insights of the regulation mechanisms of NET formation in the pathogenesis of UC.
大量证据表明中性粒细胞胞外诱捕网（NET）的形成参与了溃疡性结肠炎（UC）的炎症级联反应。然而，调控这一过程的确切机制仍不清楚。本研究旨在确定 NET 相关基因在 UC 中的作用，并揭示可能的机制。
采用两样本 MR 方法，我们利用全基因组关联研究（12366 例病例与 33609 例对照）和 FinnGen（8279 例病例与 261098 例对照）的汇总数据，研究了 NET 相关基因（NRG）与 UC 之间的相关性。主要分析采用逆方差加权法，辅之以 MR-Egger 法和加权中位数法。敏感性分析用于排除所使用的工具变量之间的异质性和多效性干扰。共定位分析用于确定鉴定的 NRG 和 UC 是否具有共同的因果变异。进行跨组织表达分析以描述靶 NRG 的表达模式，同时进行多基因相关性分析和 GSEA 分析以探讨靶 NRG 促进 UC 和 NET 形成的机制。免疫组织化学用于验证 UC 患者结肠组织中靶 NRG 的蛋白表达。
在验证了两个数据集后，有 7 个 NRG 与 UC 的发病风险相关。ITGB2 的高表达与 UC 发病风险增加相关，而 CXCR1、CXCR2、IRAK4、MAPK3、SIGLEC14 和 SLC22A4 的表达则与 UC 发病风险呈负相关。共定位分析支持 CXCR1/2 与 UC 发病风险之间的相关性。表达分析表明，CXCR1/2 在外周血中下调，但在结肠组织中上调。GSEA 分析和相关性分析表明，CXCR1/2 通过中性粒细胞趋化和 PAD4 介导的途径分别促进 UC 和 NET 的形成。免疫组织化学结果证实了 CXCR1/2 在 UC 患者结肠组织中的高表达。
通过多方法论证，本研究确定了所有 NRG 中 CXCR1/2 是 UC 的候选靶点，为 NET 形成在 UC 发病机制中的调控机制提供了新的见解。
