The Expression Of Synovial OPN And Polarization Of Macrophages And Its Correlation With Osteoarthritis

Objective:To explore the expression of synovial OPN and macrophages(SMs)polarization markers in the synovium of patients with osteoarthritis(OA)and the control group,and analyze the correlation between them and the severity of OA.Methods:This study collected 45 samples of knee synovium and cartilage from patients with OA and controls.According to the Kellgren-Lawrence grading standard,all samples were divided into control group,KL2 group,KL3 group,and KL4 group,and all cartilage samples were stained with safranin solid green and Mankin pathological score.The expressions of OPN,CD68,Arg1 and iNOS in synovium were detected by immunohistochemistry,RT-qPCR,and Western blot.The quantitative distribution of CD68~+iNOS~+SMs and CD68~+Arg1~+SMs in synovium was detected by immunofluorescence.The correlation between synovial macrophage polarization markers,OPN expression,and KL grade or cartilage Mankin pathological score was analyzed.Results:1.Immunohistochemical results showed that CD68,iNOS,Arg1,and OPN were expressed in the control group and each KL grade OA synovial group(KL2 group,KL3 group,and KL4 group).There were significant differences in the expression of CD68,iNOS,Arg1,and OPN between KL grade OA synovial groups(P<0.05).The expressions of CD68,iNOS,and OPN in the OA synovium group were higher than those in the control group,and the expressions of CD68,iNOS,and OPN in synovium increased gradually with the increase of KL grade;The expression of Arg1 in synovium was opposite.2.Immunofluorescence results showed that the number of CD68~+iNOS~+SMs in the OA synovium group was higher than that in the control group.There were significant differences in the number of CD68~+iNOS~+SMs between OA synovial groups with KL grade(P<0.05),and the number of synovial CD68~+iNOS~+SMs gradually increased with the increase of KL grade;The number of synovial CD68~+Arg1~+SMs was opposite.3.The results of RT-qPCR and Western blot showed that compared with the control group,the mRNA and protein expressions of CD68,OPN,and iNOS in OA synovium were up-regulated,and the mRNA and protein expressions of Arg1 were downregulated.4.The average optical density of iNOS in synovium was positively correlated with the average optical density of synovium OPN(r=0.852,P<0.05),and the average optical density of Arg1 was negatively correlated with the average optical density of synovium OPN(r=-0.910,P<0.05).5.The number of CD68~+iNOS~+SMs in OA synovium was positively correlated with the expression of OPN mRNA in the synovium(ρ=0.923,P<0.05).The number of CD68~+Arg1~+SMs was negatively correlated with the expression of synovial OPN mRNA(ρ=-0.800,P<0.05).6.The mean optical density of OPN in synovium was positively correlated with Mankin pathological score(ρ=0.820,P<0.05),OPN mRNA was positively correlated with Mankin pathological score(ρ=0.859,P<0.05).The average optical density of iNOS in synovium was positively correlated with Mankin pathological score(ρ=0.857,P<0.05).The mean optical density of arg1 was negatively correlated with Mankin pathological score(ρ=-0.890,P<0.05).7.The number of CD68~+iNOS~+SMs in OA synovium was positively correlated with Mankin pathological score(ρ=0.822,P<0.05).The number of CD68~+Arg1~+SMs was negatively correlated with Mankin pathological score(ρ=-0.898,P<0.05).Conclusions:1.OPN was highly expressed in the synovium of OA patients,with the accumulation of M1 macrophages and decreased numbers of M2macrophages.2.The expression of synovial OPN was positively correlated with M1 polarization of macrophages.3.The expression of synovial OPN and M1 polarization of macrophages were positively correlated with the severity of OA.