探讨膜联蛋白A1（ANXA1）在骨关节炎（OA）发生、发展过程中的表达情况及其致病机制。

以不同浓度白细胞介素-1β（IL-1β）诱导原代人软骨细胞构建类OA细胞模型，分为对照组（0 ng/L）、轻度OA组（5 ng/L）、重度OA组（10 ng/L）。免疫组化和免疫荧光验证ANXA1在软骨细胞内的定位情况。通过实时荧光定量聚合酶链反应（RT-qPCR）、Western blot分别从mRNA水平和蛋白水平检测ANXA1的表达情况。检测类OA软骨细胞中Ⅱ型胶原蛋白α1链（COL2A1）和基质金属蛋白酶13（MMP13）的表达情况，验证类OA细胞模型建立是否成功。在类OA细胞模型中进一步设立ANXA1基因沉默组、过表达组、空载对照组及单纯OA模型组。通过CCK-8法及流式细胞技术检测沉默或过表达ANXA1基因后类OA软骨细胞的增殖活力及凋亡情况，并通过Western blot检测沉默ANXA1基因后COL2A1的表达情况。应用Western blot、免疫共沉淀（Co-IP）技术检测分析ANXA1对丝裂原活化蛋白激酶（MAPK）通路的影响。多组间计量资料的比较采用方差分析，两组间计量资料的比较采用t检验。

在类OA软骨细胞模型中，ANXA1、MMP13的mRNA和蛋白表达水平随IL-1β浓度增加而升高，差异均有统计学意义（P<0.05）。CCK-8结果表明，IL-1β抑制软骨细胞增殖活力，沉默ANXA1基因可逆转该抑制效应，而过表达ANXA1基因后可进一步降低软骨细胞增殖活力。流式细胞检测结果表明，与对照组相比，过表达ANXA1基因后轻度OA组及重度OA组总凋亡率分别由（20.3±1.80）%和（29.7±1.62）%增加至（32.1±1.96）%和（54.0±1.81）%，而沉默ANXA1基因后总凋亡率则下降至（15.4±1.33）%及（23.0±2.14）%，差异均有统计学意义（P<0.05）；且过表达ANXA1基因后，COL2A1蛋白表达量与对照组相比显著下降（P<0.05），沉默ANXA1基因后则相反。Western blot、Co-IP结果表明，ANXA1表达与ERK1/2、JNK表达呈正相关。

ANXA1基因可抑制软骨细胞的增殖，沉默ANXA1基因可抑制OA软骨细胞凋亡；ANXA1基因可能通过MAPK信号通路促进软骨细胞凋亡，是OA发生及发展的重要因素。

To investigate the expression profile of Annexin A1 (ANXA1) during the onset and progression of osteoarthritis (OA), and explore its pathogenic mechanism.

Primary human chondrocytes were induced with different concentrations of IL-1β to establish an osteoarthritis-like cell model. Cells were divided into control group (0 ng/mL), mild OA group (5 ng/mL) and severe OA group (10 ng/mL). Immunohistochemistry and immunofluorescence were used to verify the subcellular localization of ANXA1 in chondrocytes. Real-time quantitative polymerase chain reaction and Western blot were applied to detect the expression differences of ANXA1 at mRNA and protein levels, respectively. The changes of collagen typeⅡα1 chain (COL2A1) and matrix metalloproteinase 13 (MMP13) in OA-like chondrocytes were detected to confirm the successful establishment of the OA cell model.Furthermore, ANXA1 silencing group, ANXA1 overexpression group, empty vector control group and simple OA model group were set up in the OA-like cell model. CCK-8 assay and flow cytometry were performed to detect cell proliferation activity and apoptosis of OA-like chondrocytes after ANXA1 silencing or overexpression. Western blot was used to determine the expression of COL2A1 after ANXA1 knockdown. Western blot and co-immunoprecipitation (Co-IP) were utilized to explore the regulatory effect of ANXA1 on the MAPK signaling pathway. Analysis of variance was used to compare the measurement data among multiple groups, while t test was used to compare the measurement data between two groups.

In the OA-like chondrocyte model, the mRNA and protein expression levels of ANXA1 and MMP13 showed an upward trend with the increase of IL-1β concentration, with statistically significant differences (P < 0.05). The CCK-8 results showed that IL-1β inhibited chondrocyte proliferation activity, silencing the ANXA1 gene reversed this inhibitory effect, while overexpression of the ANXA1 gene further reduced chondrocyte proliferation activity. The flow cytometry results showed that compared with the control group, the total apoptosis rates in mild and severe OA groups were elevated from (20.3±1.80)% and (29.7±1.62)% to (32.1±1.96)% and (54.0±1.81)% after ANXA1 overexpression, with statistically significant differences (P < 0.05). In contrast, ANXA1 silencing decreased the total apoptosis rates to (15.4±1.33)% and (23.0±2.14)%. Moreover, ANXA1 overexpression markedly downregulated COL2A1 protein expression relative to the control group (P < 0.05), while ANXA1 knockdown exerted the opposite effect. Western blot and co-immunoprecipitation (Co-IP) assays confirmed that the expression of ANXA1 was positively correlated with the expressions of ERK1/2 and JNK.

The ANXA1 gene inhibits chondrocyte proliferation, and silencing the ANXA1 gene inhibits OA chondrocyte apoptosis. ANXA1 gene may promote chondrocyte apoptosis via the potential MAPK signaling pathway and is an important factor in the occurrence and development of OA.