Characterization of the Interleukin-17 Effect on Articular Cartilage in a Translational Model. An Explorative Study

Abstract

Background Osteoarthritis (OA) is a progressive, chronic disease characterized by articular cartilage destruction. The pro-inflammatory cytokine IL-17 levels have been reported elevated in serum and synovial fluid of OA patients and correlated with increased cartilage defects and bone remodeling. The aim of this study was to characterize an IL-17-mediated articular cartilage degradation ex-vivo model and to investigate IL-17 effect on cartilage extracellular matrix protein turnover. Methods Full-depth bovine femoral condyle articular cartilage explants were cultured in serum-free medium for three weeks in the absence, or presence of cytokines: IL-17A (100 ng/ml or 25 ng/ml), or 10 ng OSM combined with 20 ng/ml TNFα (O+T). RNA isolation and PCR analysis were performed on tissue lysates to confirm IL-17 receptor expression. GAG and ECM-turnover biomarker release into conditioned media was assessed with dimethyl methylene blue and ELISA assays, respectively. Gelatin zymography was used for matrix metalloproteinase (MMP) 2 and MMP9 activity assessment in conditioned media, and shotgun LC-MS/MS for identification and label-free quantification of proteins and protein fragments in conditioned media. Western blotting was used to validate MS results. Results IL-17RA mRNA was expressed in bovine articular cartilage and the treatment with IL-17A did not interfere with metabolic activity of the model. IL-17A induced cartilage breakdown; conditioned media GAG levels were 3.6-fold-elevated compared to untreated. IL-17A [100 ng/ml] induced ADAMTS-mediated aggrecan degradation fragment release (14-fold increase compared to untreated) and MMP-mediated type II collagen fragment release (6-fold-change compared to untreated). MS data analysis revealed 16 differentially expressed proteins in IL-17A conditioned media compared to untreated. CHI3L1 upregulation in conditioned media in response to IL-17A was confirmed by Western blotting. Conclusions We showed that IL-17A has cartilage modulating potential. It induces collagen and aggrecan degradation indicating an upregulation of MMPs. This was confirmed by zymography and mass spectrometry data. We also showed that the expression of other cytokines is induced by IL-17A, which provide further insight to the pathways that are active in response to IL-17A. This exploratory study confirms that IL-17A may play a role in cartilage pathology and that the applied model may be a good tool to further investigate it.

Extracorporeal Shockwave Therapy Modulates the Expressions of Proinflammatory Cytokines IL33 and IL17A, and Their Receptors ST2 and IL17RA, within the Articular Cartilage in Early Avascular Necrosis of the Femoral Head in a Rat Model

“…Recently, IL33 has been reported to be linked with IL17 in terms of contributing to immunological dysfunction in inflammatory diseases [ 41 , 42 ]. The IL17 receptor is a complex that consists of IL17RA, IL17RB, IL17RC, IL17RD, and IL17RE [ 43 ]. IL17RA is a key component required for IL17A activity, and blocking of IL17 binding by IL17RA could inhibit the expression of IL-6 to prevent synovial inflammation in arthritis [ 44 ].…”

“…IL17RA is a key component required for IL17A activity, and blocking of IL17 binding by IL17RA could inhibit the expression of IL-6 to prevent synovial inflammation in arthritis [ 44 ]. A high expression of IL17A contributes to cartilage degradation by inducing disintegrin-like and metalloproteinase with thrombospondin motifs (ADAMTS) protease and matrix metalloprotease in the articular cartilage in arthritis [ 43 ]. A high expression of IL17A was observed in the hyaline cartilage, and receptor IL17RA was evaluated with regards to hypertrophy chondrocyte ( Figure 6 ).…”