Clinical Studies Of Inflammatory Cytokines In Osteonecrosis Of The Femoral Head

Backgrounds:The role of inflammatory cytokines has been widely acknowledged in many diseases,thus numerous study had focused on them to investigate the pathophysiological features of diseases,especially those with elevated inflammatory cytokines in peripheral circulation and localized tissue,for example,rheumatoid arthritis and osteoarthritis.However,in the research field of osteonecrosis of the femoral head(ONFH),there were only a few reports about inflammatory cytokines.After reviewing the related literatures,the following issues have been found,which can be investigated by clinical studies:The first issue is about the correlations between expression of interleukin(IL)-33 in necrotic femoral head and disease staging in pre-collapsed ONFH,and additionally the correlation between local and peripheral expressions.Previous clinical studies revealed IL-33 level in peripheral blood were different between pre-collapsed and collapsed ONFH,indicating it was a potential biomarker for ONFH.However,correlation between IL-33 and disease staging has not yet been confirmed in peripheral or local expression in pre-collapsed ONFH,and the correlation between local and peripheral expression is not clear.The second issue is about the correlation between inflammatory cytokines and cartilage metabolism in ONFH.Previous researches showed that there was a very high level of cartilage metabolism in ONFH,even in the pre-collapsed stage.Besides that,it has been confirmed that synovitis existed in hip joint of ONFH,and also many inflammatory cytokines presented in synovial fluid of collapsed stage,but the level of inflammatory cytokines and the presence of cartilage metabolism are unclear.The third issue concerned about the effects of adipokines on inflammatory cytokines and cartilage metabolism in ONFH.The distinct level of inflammatory cytokines and cartilage metabolism markers varied in patients with the same stage of ONFH.Taking into account that the metabolism disorders are common in patients with ONFH,and the influence of adipokines,which were highly related to metabolism disorders,on inflammatory cytokines and cartilage metabolism in osteoarthritis was clear.Therefore it is worthy to analysis adipokines in ONFH compared with those in osteoarthritis,and evaluated whether adipokines effect inflammatory cytokines and cartilage metabolism in the joint of ONFH.Clinical studies were designed for the three issues above:Part I: Expression of IL-33 in pre-collapsed ONFH and its correlation with radiological staging;Part II: Inflammatory cytokines in pre-collapsed ONFH and its correlation with cartilage metabolism;Part III: Adipokines in ONFH and its correlation with inflammatory cytokines and cartilage metabolism.Materials and methodsPart I:Pre-collapsed ONFH were enrolled.Peripheral blood and bone marrow fluid were obtained.The levels of IL-33 in peripheral blood and bone marrow fluid were determined by enzyme linked immunosorbent assay(ELISA).The levels of IL-33 in different kinds of samples were compared.In different stages,the necrotical bone and the number of osteoclasts were observed,and the levels of IL-33 in peripheral blood,synovial fluid and bone marrow fluid were compared.Part II:Cases of Ficat II stage and cases of III stage as controls were enrolled,patients' peripheral blood and synovial fluid and femoral head specimens were obtained.the levels of IL-6,IL-1?,IL-17 and tumor necrosis factor alpha(TNF-?),and matrix metalloproteinase(MMP)-3,MMP-13,inhibitor of metalloproteinase(TIMP)-1 and type II collagen crosslinked C terminal peptide(CTX-II)levels were determined in peripheral blood and synovial fluid by using ELISA method.Articular cartilage was evaluated,and levels of these cytokines were compared between pre-collapsed and collapsed stages,and the Collagen II and MMP-13 were analyzed by immunohistochemistry between necrotic and intact regions of the articular cartilage as evaluations of cartilage metabolism.Part III:The levels of adiponectin,leptin and soluble leptin receptor(sOB-R)were determined in the remaining peripheral blood and synovial fluid in the second part by ELISA method.The distributions of adiponectin,leptin and sOB-R in peripheral blood and synovial fluid as well as the level of bioactive leptin(ratio of leptin and sOB-R)in synovial fluid were compared with those in osteoarthritis.The correlations between levels of these adipokines and levels of IL-6,MMP-13 and CTX-II measured in the second part was analyzed.ResultsPart I:In paried peripheral blood and bone marrow fluid samples obtained from the same cases,IL-33 expressions in bone marrow fluid were higher than in the peripheral blood,the difference tended to be significant;the levels of paired samples had moderate correlation which was tended to be significant.Compared to I stage,intramedullary tissue of II stage had more empty bone lacuna?infiltration of inflammatory cells and more osteoclasts.In peripheral blood,the IL-33 levels of IIB stage was significantly higher than that in IIA stage;in bone marrow fluid,the median levels of IL-33 in each stage showed a tendency to increase with staging.Part II:IL-6 in synovial fluid were higher than the levels of peripheral blood;IL-1?,IL-17,TNF-? in peripheral blood and synovial fluid were not measurable in most of samples;the expression of MMP-3,TIMP-1 and CTX-II in the joint fluid is higher than the level of peripheral blood,whereas the level of MMP-13 between peripheral blood and synovial fluid had no obvious difference.In the synovial fluids,all were similar between II and III stage.Articular cartilage of II stage showed degenerative magnifications,as decreased Collagen II expressions around chdrocytes and positive expression of MMP-13 in chdrocytes.Part III:The levels of adiponectin and sOB-R in peripheral blood were higher than those in synovial fluid,while the levels of leptin had no significant difference.As to adiponectin and leptin,the ratios of synovial fluid and peripheral blood in ONFH was similar to those in osteoarthritis,the sOB-R were higher in ONFH,but the bioactive leptin were simialr.There was a positive correlation between adiponectin and IL-6 in joint fluid of ONFH.ConclusionsPart I:The levels of IL-33 in necrotic femoral head were correlated with disease staging in pre-collapsed ONFH;IL-33 in the peripheral circulation of patients with pre-collpased ONFH may derived from the necrotic femoral head,indicating its potential role of biomarker for ONFH.Part II:Levels of IL-6 and cartilage metabolism in pre-collapsed ONFH were comparable with those in collapsed stage;increased Collagen II metabolism exsited in necrotic region of articular cartilage that may due to positive expression of MMP-13.Part III:The distributions of adiponectin and leptin in ONFH were similar with that of osteoarthritis,the level of adiponectin may affect the level of IL-6 in the joint of ONFH.