CORRELATION BETWEEN THE EXPRESSION OF S100A12 IN THE BLOOD AND SYNOVIUM AND THE SEVERITY OF HIP OSTEOARTHRITIS

Jiaxiang Yan¹, Kewei Tian¹, Kejie Fan¹, Wenjia Shi², Ke Chen^{1, *}

¹No.1 Department of Hip Injury and Disease, Orthopedic Hospital of Henan Province, Luoyang, PR China - ²No.2 Department of Comprehensive Orthopaedic,Orthopedic Hospital of Henan Province, Luoyang, PR China

Objective: To explore the relationship between the expression of the calcium-binding protein S100A12 in the blood and synovium and the severity of hip osteoarthritis (OA). 

Methods: In this study, 33 patients with hip OA who underwent hip replacement in our hospital between 2017 and 2018 were selected as the study object (OA group), and 41 patients with femoral neck fracture in our hospital at the same time were selected as the control group. X-ray films of the hip joints of subjects in the OA group were graded according to the Kellgren–Lawrence (KL) grading system. Synovial tissue and blood samples were collected from the two groups. S100A12 was detected via immunohistochemical analysis (SP method) and enzyme-linked immunosorbent assay (ELISA). The results for S100A12 expression were analysed via semi-quantitative analysis using IPP software.

Results: The serum S100A12 level of the OA group was higher than that of the control group, and the difference was statistically significant (P<0.01); the level of S100A12 in the synovial tissue of the OA group was higher than that of the control group, and the difference was statistically significant (P<0.01). Comparing patients with different KL grades, the serum S100A12 level of grade 4 patients was higher than that of grade 3 patients, and the difference was statistically significant (P < 0.01); the level of S100A12 in the synovial tissue of grade 4 patients was higher than that of grade 3 patients, and the difference was statistically significant (P<0.01); the mean optical density (MOD) of the synovial tissue of grade 4 patients was higher than that of grade 3 patients, but the difference was not statistically significant (P>0.05). Immunohistochemical analysis of S100A12 showed that some synovial cells had positive reactions in cytoplasm and microvascular neutrophils. S100A12 was expressed in both the OA group and the control group. The MOD of the synovial tissue of the OA group was significantly higher than that of the control group (0.12±0.07; P<0.01). Pearson correlation was used to analyse the relationship between serum S100A12 level, synovial tissue S100A12 level and immunohistochemical MOD. The results showed that there was no correlation between serum S100A12 level and immunohistochemical MOD (γ=0.315, P=0.074), there was a positive correlation between synovial tissue S100A12 level and immunohistochemical MOD (γ=0.411, P=0.017), and there was no significant correlation between serum S100A12 level and synovial tissue S100A12 level (γ=0.207, P=0.248).

Conclusion: The calcium-binding protein S100A12 is expressed in the blood and synovium in direct proportion to the severity of hip OA. Therefore, early detection of increased S100A12 levels is beneficial for OA patients; these levels can be used to monitor the degree of OA and provide guidance for clinical treatment.