骨关节炎（OA）是最常见的与年龄相关的关节疾病，其特征为慢性炎症、进行性关节软骨破坏和亚软骨下骨硬化。越来越多的证据表明，微小RNA（miRNA）在各种疾病中发挥关键作用，但miRNA在骨关节炎中的具体机制尚不清楚。本研究旨在调查miR-181a-5p在OA中的表达水平及其相关机制的作用。本文通过生物信息学分析在OA数据集中鉴定了关键基因DEAD-box RNA helicase 3X (DDX3X)。同时，筛选miRNAs靶向DDX3X，并选择miR-181a-5p作为下一步研究对象。然后，我们使用不同浓度的白细胞介素-1β（IL-1β）诱导的体外关节炎模型，并发现IL-1β能够刺激细胞释放一氧化氮。通过逆转录-定量聚合酶链反应（RT-qPCR）检测了IL-1β诱导的浓度为10ug/mL的小鼠软骨细胞系ATDC5中miR-181a-5p和DDX3X的表达水平。IL-1β诱导ATDC5细胞中miR-181a-5p的表达下降，并增加DDX3X的表达。转染mimic miR-181a-5p或inhibitor miR-181a-5p至ATDC5细胞，并通过酶联免疫吸附试验检测细胞中炎症介质的水平，结果显示miR-181a-5p能够减少细胞模型中肿瘤坏死因子-α、IL-1β、IL-6和诱导型一氧化氮合酶的释放。荧光素酶报告基因试验确认miR-181a-5p结合位点位于DDX3X基因3'-非翻译区（3'-UTR）内，并且DDX3X受miR-181a-5p的负调控。救助实验证实miR-181a-5p通过靶向DDX3X的3'-UTR区域减少DDX3X的表达，从而减少炎症因子的释放。最后，本文使用西方印迹检测miR-181a-5p调控OA的机制。结果显示干扰miR-181a-5p的表达能够上调DDX3X蛋白的表达，增加核因子- kappaB（NF-κB）相关蛋白的表达，并降低OA的炎症反应，从而增加基质金属蛋白酶MMP-3和MMP-13的分泌。综上所述，研究结果表明miR-181a-5p可能是治疗人类OA的有希望的治疗靶点。©2023年。BioMed Central Ltd.，Springer Nature的一部分。

Osteoarthritis (OA) is the most common age-related joint disease, characterized by chronic inflammation, progressive articular cartilage destruction and subchondral osteosclerosis. More and more evidence showed that microRNAs (miRNAs) play a key role in various diseases, but the specific mechanism of miRNAs in OA is not clear. The purpose of this study was to investigate the expression level and role of miR-181a-5p in OA and its related mechanism. Here we identified the key gene DEAD-box RNA helicase 3X (DDX3X) in the OA dataset by bioinformatics analysis. At the same time, miRNAs targeting DDX3X were screened, and miR-181a-5p was selected as the next research object. Then we used different concentrations of interleukin-1 beta (IL-1β)-induced in vitro model of arthritis, and found that IL-1β can stimulate cells to release nitric oxide. The expression levels of miR-181a-5p and DDX3X in mouse chondrocyte cell line ATDC5 induced by IL-1β at a concentration of 10ug/mL were detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). IL-1β induced a decrease in the expression of miR-181a-5p and an increase in the expression of DDX3X in ATDC5 cells. mimic miR-181a-5p or inhibitor miR-181a-5p were transfected into ATDC5 cells, and the levels of inflammatory mediators in the cells were detected by enzyme-linked immunosorbent assay, and the results showed that miR-181a-5p could reduce the release of tumor necrosis factor-α, IL-1β, IL-6 and inducible nitric oxide nitric oxide synthase in a cellular model of arthritis. Luciferase reporter assays confirmed that the miR-181a-5p binding site was in the DDX3X gene 3'-untranslated region (3'-UTR), and DDX3X was negatively regulated by miR-181a-5p. Rescue assays confirmed that miR-181a-5p reduced the expression of DDX3X by targeting the 3'-UTR region of DDX3X, thereby reducing the release of inflammatory factors. Finally, in this paper, western blot was used to detect the mechanism of miR-181a-5p regulating OA. The results showed that interfering with the expression of miR-181a-5p could up-regulate the expression of DDX3X protein, increase the expression of nuclear factor- kappaB (NF-κB) related proteins, and reduce the inflammatory response of OA, thereby increasing the secretion of the matrix proteinases MMP-3 and MMP-13. Taken together, the results of the study suggested that miR-181a-5p may be a promising therapeutic target for the treatment of human OA.© 2023. BioMed Central Ltd., part of Springer Nature.