Mechanisms Of IL-1? On Post-traumatic Osteoarthritis In Mice

Osteoarthritis(OA),also known as aseptic arthritis and osteoarthropathy,is a common skeletal degenerative disease in the population.Cartilage injury,proliferation of osteophyte and subchondral bone changes can be seen in patients with OA.Age,sex,bad working posture,and weight-bearing etc are main factors for OA.Recently,the role of cytokines,especially inflammatory factors,in the occurrence and development of OA has attracted more and more attention,especially the role of interleukin(IL)-1?.The purpose of this study was to investigate the role of IL-1? and its upstream and downstream factors in traumatic osteoarthritis in mice,and to explore the role of interruption of IL-1 beta in post-traumatic osteoarthritis in mice.This study is divided into two parts In the first part,we established a mouse posttraumatic osteoarthritis model by medial meniscus collateral ligament dismemberment,observing the histological changes on the knee joint of mice.In the second part,based on the model of osteoarthritis,we explore the possible therapeutic effect of IL-1? by blocking the function of IL-1?.Part ?: Establishment of a mouse posttraumatic osteoarthritis modelObjectives: To observe the histological changes of the osteoarthritis model in mice induced by medial meniscus collateral ligament dismemberment.Methods: Male C57BL/6 mice aged 6-8 weeks were randomly divided into three groups: operation group,sham operation group and blank control group.In the operation group,the right knee joint capsule was incised and the medial meniscus collateral ligament was dismembered.In the sham operation group,only the knee joint capsule was incised,while in the blank control group,no treatment was given.At 8weeks after operation,mice were executed and joint specimens were taken for H&E staining and safranine and fast green double staining.Results: At 8 weeks after operation,a large range of inflammatory cell aggregation and fibrosis were observed in the knee joint space in the operation group.The method of safranine and fast green double staining is one of the important methods to observe bone and cartilage injury.In safranine and fast green double staining sections,the knee joint tissues of the operation group showed obvious cartilage damage and rupture,local damage extending to the subchondral bone;There was also seen other pathological changes such as articular surface disappeared or blurred,chondrocyte abnormal proliferated and disordered arrangement etc.;Safranine staining was abnormal,local tissue lost staining.In the sham operation group,there were smaller inflammatory cell aggregation and fibrosis in the knee joint space,and chondrocyte destruction and light safranine staining in the local articular cartilage tissue than operation group.the result of inflammatory score showed that the inflammatory score of the operation group(2.50±0.20)and the sham operation group(1.67±0.21)were slightly higher than that of the blank control group(0.17±0.17),and the inflammatory degree of the operation group was significantly higher than that of the sham operation group(P<0.05).Mankin's score is one of the important criteria for evaluating osteoarthritis.Compared with the blank control group(1.83±0.17),the Mankin's score of the operation group(9.33±0.49)and the sham operation group(3.83±0.40)increased in varying degrees,and the score of the operation group was higher than that of the sham operation group(P<0.01).Conclusions: In this study,we successfully established a model of traumatic osteoarthritis in mice with medial meniscus collateral ligament dismemberment,which is an ideal model for the study of osteoarthritis.Part ?: Mechanisms of IL-1? on post-traumatic osteoarthritis in miceObjectives: To explore the mechanisms of IL-1? on mouse posttraumatic osteoarthritis modelMethods: Male C57BL/6 mice aged 6-8 weeks were randomly divided into three groups: operation group,operation + anti-IL-1? group and PBS control group.The model of osteoarthritis in mice is the same as Part ?.The operation + anti-IL-1? group received intraperitoneal injection of 100 ?l 0.4 ug/ml IL-1? antibody solution every 10 days,while the operation group and PBS control group received intraperitoneal injection of 100 ?l PBS solution.The mice in each group were killed at 1,4 and 8weeks after operation.The expression of IL-1? in serum was determined by ELISA,and the expression level of IL-1? and its upstream and downstream factors in knee joint tissue was determined by RT-qPCR and Western Blot assay.The knee joint tissues were taken for H&E staining,safranine and fast green double staining and immunohistochemical staining to evaluate the difference of results at different time points in different treatments.Results: 8 weeks after operation,severe bone and cartilage injuries were observed in safranine and fast green double staining sections of knee joints of mice in the operation group,while the bone and cartilage injuries in the operation + anti-IL-1?group were milder than those in the operation group.Mankin's score showed that compared with PBS control group(1.5±0.22),the score of operation group(10.00±0.58)and operation + anti-IL-1? group(6.67±0.49)increased in varying degrees(P<0.01),and the score of operation group was higher than that of operation + anti-IL-1? group(P<0.01).RT-qPCR results showed that compared with PBS control group,the expression levels of Nalp3 and caspase-1 in operation group were increased in varying degrees(P<0.05 or P<0.01).The expression of Nalp3 and caspase-1 protein in the operation group was significantly high than that in the operation + anti-IL-1? group(P<0.05).Conclusions: Blocking IL-1? receptor significantly delayed the development of osteoarthritis in mice,suggesting that osteoarthritis can be treated by blocking the effect of inflammation on articular cartilage.Nalp3 may play a positive regulatory role in the development of osteoarthritis in mice.