类风湿性关节炎（RA）和骨关节炎（OA）的遗传架构仍不明确。尽管RA和OA的病因相差很大，但它们共享滑膜炎症、风险因素和一些与疾病相关的基因，包括参与细胞外基质相互作用和免疫细胞信号转导的整合素子单位β2（ITGB2）/CD18基因。然而，ITGB2基因变异的功能作用、其循环表达模式以及它们在RA和OA中的临床可用性尚未被探索。我们的研究评估了ITGB2 rs2070946单核苷酸多态性与RA和OA易感性的关联，以及其对ITGB2 mRNA表达的影响，并探讨了血清ITGB2表达在RA和OA诊断中的潜力。本研究包括70名RA患者、70名原发性OA患者和60名健康志愿者。采用qPCR进行基因分型和基因表达分析，运用生物信息学分析构建了ITGB2的蛋白质相互作用（PPI）网络。与健康对照组相比，RA和OA患者的血清ITGB2 mRNA表达上调。ITGB2 rs2070946与两种疾病的风险逐渐增加相关。携带rs2070946 CC或TC + CC基因型的RA患者血清ITGB2表达较TT基因型携带者更高。相同地，携带次等位基因型CC的OA患者血清ITGB2表达较携带TT、TC或TT + TC基因型者更高。血清ITGB2表达在受试者工作特征分析中显示出显著的RA和OA诊断潜力。在RA中，血清ITGB2表达与类风湿因子和疾病活动评分28（DAS28）呈正相关。ITGB2-PPI网络富集了细胞间黏附、ICAM-3受体活性、T细胞激活、白细胞黏附、补体结合、NF-κB、肿瘤坏死因子和白细胞介素信号转导通路。这些发现表明，ITGB2 rs2070946对RA和OA均为新的基因生物标志物，可以改变ITGB2表达。血清ITGB2表达有助于及时诊断RA和OA。© 2023. 万维读者科技有限公司，Springer Nature的一部分。

The genetic architecture of rheumatoid arthritis (RA) and osteoarthritis (OA) are still unclear. Although RA and OA have quite different causes, they share synovial inflammation, risk factors, and some disease-associated genes, including the integrin subunit β2 (ITGB2)/CD18 gene involved in extracellular matrix interactions and immune cell signaling. However, the functional role of ITGB2 genetic variants, its circulating expression pattern, and their clinical usefulness in RA and OA remain unexplored. Our study appraised the association of ITGB2 rs2070946 single nucleotide polymorphism with the vulnerability to RA and OA and its influence on ITGB2 mRNA expression, along with the potential of serum ITGB2 expression in RA and OA diagnosis.This study included 70 RA patients, 70 primary OA patients, and 60 healthy volunteers. Genotyping and gene expression analysis were performed using qPCR. Bioinformatics analysis was employed to construct the protein-protein interaction (PPI) network of ITGB2.Serum ITGB2 mRNA expression was upregulated in both RA and OA compared to healthy controls. ITGB2 rs2070946 was associated with escalating risk of both diseases. RA patients harboring the rs2070946 CC or TC + CC genotypes had higher serum ITGB2 expression than the TT genotype carriers. Likewise, OA patients having the minor homozygote CC genotype had higher serum ITGB2 expression than those carrying the TT, TC or TT + TC genotypes. Serum ITGB2 expression showed profound diagnostic potential for RA and OA in receiver-operating characteristic analysis. In RA, serum ITGB2 expression positively correlated with rheumatoid factor and disease activity score 28 (DAS28). The ITGB2-PPI network enriched in cell-cell adhesion, ICAM-3 receptor activity, T-cell activation, leukocyte adhesion, complement binding, and NF-κB, tumor necrosis factor, and interleukin signaling pathways.These findings embrace the impact of ITGB2 rs2070946 as a novel genetic biomarker of both RA and OA, which could alter the ITGB2 expression. Serum ITGB2 expression could aid in timely diagnosis of RA and OA.© 2023. BioMed Central Ltd., part of Springer Nature.