Expression Of Interleukin-37 In Infrapatellar Fat Pad Of Knee Osteoarthritis

Background:Knee osteoarthritis is a chronic disease involving mechanical changes,cartilage wearing,osteophyte proliferation,inflammatory factors and inflammatory cells.Inflammatory mediators,pro-inflammatory cytokines and anti-inflammatory factors also play an important role in the development of knee osteoarthritis and participate in the regulating the progress of the disease.Infrapatellar fat pad of knee joint is the place where many pro-inflammatory cytokines and anti-inflammatory factors are secreted and stored.These inflammatory factors or anti-inflammatory factors can regulate articular cartilage.As a newly discovered cytokine,IL-37 has been extensively reviewed in other diseases with anti-inflammatory effect.Recent literatures had shown that IL-37 might be associated with osteoarthritis.It can inhibit the release of inflammatory mediators IL-1?,TNF-? and IL-6,inhibit osteoclasts and the expression of MMP3 in chondrocytes.IL-37 also can slow down the degeneration of cartilage.However,no studies have demonstrated that IL-37 is expressed in the Infrapatellar fat pad.The expression of IL-37 in the infrapatellar fat pad and the role of IL-37 in the infrapatellar fat pad in knee osteoarthr:itis is one of the key questions to study the anti-inflammatory factors in the development of osteoarthritis.Our research are trying to elucidate the difference of the expression of IL-37 in patients with osteoarthritis and normal people,and to reveal the possible mechanism of IL-37 in infrapatellar fat pad,to further explore the development and regulation mechanism of osteoarthritis,and to explore the new direction of OA treatment.Objective:The aim of this study is to investigate the possible effect of anti-inflammatory therapy of IL-37 on the development of osteoarthritis.What more,our research is going to explore the expression of IL-37 in the infrapatellar fat pad of patients with OA,and to analyze the relationship between IL-37 and the severity of osteoarthritis.Method:To explore the expression of IL-37 in the infrapatellar fat pad of patients with osteoarthritis,we detected the expression of IL-37 in the infrapatellar fat pad of OA patients who are undergoing total knee arthroplasty.After that,we compared IL-37 in the infrapatellar fat pad of OA patients with that of patients undergoing anterior cruciate ligament reconstruction.Meanwhile,the expressions of IL-1,IL-6,IL-18 and TNF-? in the infrapatellar fat pads of two groups were measured.The expressions of IL-37,IL-1,IL-6,IL-18 and TNF-? in the infrapatellar fat pads were analyzed and the correlation between the expressions and inflammatory or imaging indexes was analyzed.Result:IL-1,IL-6,IL-18 and TNF-a in infrapatellar fat pad might be associated with the progression of osteoarthritis.The expression is positively correlated with the radiological severity of osteoarthritis.The expression of IL-37 in infrapatellar fat pad was negatively correlated with the radiological severity of osteoarthritis.No significantly correlation were shown between expressions of IL-1,IL-6,IL-18,IL-37,TNF-? in infrapatellar fat pad and CRP or ESR in peripheral blood.No significantly correlation were shown between expressions of IL-1,IL-6,IL-18,IL-37,TNF-? in infrapatellar fat pad and WOMAC pain score.Conclusion:IL-37 is expressed in the infrapatellar fat pad of patients with osteoarthritis,and its expression level is negatively correlated with the radiological grade of osteoarthritis.IL-1,IL-6,IL-18,TNF-? and other pro-inflammatory cytokines in the infrapatellar fat pad participate in the inflammatory microenvironment of osteoarthritis.IL-37 in infrapatellar fat pad may have anti-inflammatory effect in patients with osteoarthritis.