Research On The Correlation Between The Expression Of IL-15 In Articular Cartilage Of Knee Osteoarthritis And The Severity Of The Disease

Objective:In the occurrence and development of knee osteoarthritis(KOA),pro-inflammatory factors play a pivotal role,but the specific target factors involved in its pathogenesis are still unclear.The aim of this study was to observe the expression of interleukin-15(IL-15)at both gene and protein levels in articular cartilage of KOA with different lesions,and to analyze the correlation between its expression and the degree of articular cartilage degeneration and Kellgren-Lawrence(K-L)grade.Methods:Knee cartilage specimens were from KOA patients who underwent total knee arthroplasty or unicompartmental knee arthroplasty.A total of 30 patients met the inclusion criteria.All patients have undergone X-ray examination before surgery.According to the K-L grading standard,30 patients were divided into three groups:mild group(K-L grade II)8 cases;moderate group(K-L grade III)10 cases;severe group(K-L grade IV)12 cases.First,the collected knee articular cartilage specimens were sectioned and stained with hematoxylin-eosin(HE).Then the degree of degeneration of KOA articular cartilage were observed under microscope,and Mankin pathological score was performed on the degree of articular cartilage degeneration of each group of specimens.The expression of IL-15 m RNA in articular cartilage was detected by Quantitative Real-Time Polymerase Chain Reaction(qRT-PCR),and the immunohistochemical(IHC)method was used to detect the expression of IL-15protein in knee joint cartilage specimens.Finally,the correlation between the expression of IL-15 and the degree of cartilage degeneration and K-L grade was analyzed by statistical method.Results:1.HE stain:(1)Mild group:the cartilage matrix was evenly stained,The cartilage layer is slightly thin and the surface is not flat,occasionally cracks were formed,the difference of cells was not obvious,the cell arrangement was not regular,a small number of clustered chondrocytes were visible,occasionally vacuolar cells,and the tidal line was complete.(2)Moderate group:uneven staining of cartilage matrix,the surface of cartilage is rough,even defect,surface cracks and fibrosis,irregular cell morphology,disordered arrangement,chondrocytes gather in large numbers,incomplete tidal line.(3)Severe group:the staining of cartilage matrix was severely reduced,fibrosis is seen in the deep layers of cartilage,part of the cartilage layer structure was completely destroyed,the number of cells decreased and arranged disorderly.2.Mankin score:mild group:2.00±1.07 points,moderate group:5.50±0.85points,severe group:8.75±1.71 points.The Mankin scores of the three groups were different,and the Mankin scores of mild group,moderate group and severe group showed a gradually increasing trend,with statistical significance(χ2=24.933,P<0.001).3.qRT-PCR:mild group:0.43±0.08,moderate group:0.94±0.38,severe group:2.92±0.75.The expression level of IL-15 m RNA in the mild group,the moderate group and the severe group showed a gradually increasing trend,with statistical significance(χ2=25.554,P<0.001).4.IHC:mild group:2.00±1.07,moderate group:5.20±1.03,severe group:10.00±1.48.The expression of IL-15 protein in the mild,moderate,and severe groups showed a gradual upward trend,with statistical significance(χ2=26.004,P<0.001).5.Spearman analysis results:IL-15 protein expression was significantly positively correlated with K-L grade(r_s=0.947,P<0.001),and IL-15 m RNA expression was significantly positively correlated with K-L grade(r_s=0.939,P<0.001).The results showed that the expression level of IL-15 increased with the increase of K-L grade.There was a positive correlation between the expression of IL-15 protein and Mankin score(r_s=0.871,P<0.001);IL-15 gene expression is positively correlated with Mankin score(r_s=0.882,P<0.001),which indicated that the higher the Mankin score,the higher the expression of IL-15 in articular cartilage.Conclusion:The expression of IL-15 in articular cartilage was correlated with the pathological degree in patients with KOA,and the expression of IL-15was positively correlated with the degree of articular cartilage degeneration.