| Objective:Rheumatoid arthritis(RA)is a chronic autoimmune disease characterized by synovitis,symmetrical and destructive joint disease.Although its pathogenesis is not well known,it was found that the incidence of RA related to immune,genetic,infectious,nutritional,environmental and other factors by the long-term research.However,previous studies have reported that serum amyloid A(SAA)may be related to the pathogenesis of RA.In this study,a variety of immunological techniques were used to analyze the expression of SAA in serum,synovial fluid and synovium in patients with RA.And the potential role of SAA in RA pathogenesis was further investigated.Besides,a three-dimension in vitro model of angiogenesis was constructed to explore the role of SAA receptor class B type 1 scavenger receptor(SR-B1)in angiogenesis mechanisms of RA This study was designed to lay the foundation for SAA in the pathogenesis of RA and the role of angiogenesis.Methods:1.SAA levels in serum and synovial fluid in each group were detected.The correlations between SAA levels in serum and synovial fluid in RA and OA were analyzed,respectively.Sera SAA content was determined by Western blot.2.The expression of SAA in RA and OA synovium was detected by immunohistochemistry.3.The expression of SR-B1 in RA synovium and Human umbilical vein endothelial cells(HUVECs)was analyzed by immunohistochemistry and immunofluorescent staining.4.The role of SAA in HUVECs proliferation and migration were detected by MTT assay and cell migration assay.5.The role of SAA receptor class B type 1 scavenger receptor(SR-B1)in RA angiogenesis mechanisms were detected by constructing a three-dimension in vitro model of angiogenesis.Results:1.The serum levels of SAA were significantly higher in RA[(318.11±132.37)?g/L]than that in OA[(126.62±47.43)?g/L]and healthy control[(126.69±41.36)?g/L](P=0.00).In RA,SAA levels in synovial fluid were significantly higher[(570.56±473.48)?g/L]compared to that in OA[(129.47±33.07)?g/L](P=0.04).And SAA levels in serum and synovial fluid were positively correlated(r=0.80,P=0.03).Western blot results showed that SAA bands were found in serum samples of each group,and higher expression of SAA were seen in RA.2.Pathology showed that SAA was observed in endothelial cells,synovial fibroblasts,macrophages and perivascular areas in RA synovium.In OA.SAA was observed in perivascular areas and synovial fibroblasts.3.Immunohistochemistry results showed that SR-B1 was observed in the synovial lining and sublining layers of RA synovium.Minimal staining was seen in endothelial cells in OA synovium.Immunofluorescence results showed that SR-B1 was expressed in the cytoplasm in HUVECs.4.MTT assay and cell migration assay demonstrated that SAA can stimulate the proliferation and migration of HUVECs.Then this effect was significantly reduced by adding the SR-B1 receptor antagonist.5.In the three-dimension in vitro model of angiogenesis,SAA and vascular endothelial growth factor(VEGF)had the same effect in stimulating angiogenesis.Then the SAA stimulating effect was significantly reduced by adding the SR-B1 receptor antagonist.Conclusions:1.In RA,SAA levels in both serum and synovial fluid were significantly higher than that in control.And SAA levels in serum and synovial fluid were positively correlated.Higher expression of SAA in RA was observed.Our results suggest that SAA may play a role in inflammation reaction and joint destruction of RA.2.SR-B1 receptor expressed in HUVECs in RA synovial tissue.SAA can be combined with SR-B1 receptor to mediate HUVECs proliferation,migration and angiogenesis,which indicate that SAA may be directly involved in RA pannus formation by inducing endothelial cell proliferation,migration and angiogenesis,and play a role in bone and cartilage damage in RA patients. |
PDF Full Text Request