Tissue Phosphoproteome Directed Proteomics Revealed IL-1? Can Mediate TNF-dependent Secretome Of Human Synoviocytes

Synovitis is a key contributor to the inflammatory environment in osteoarthritis(OA)joints.Currently,the biological therapy of OA is not satisfactory in multiple single-target trials on anti-TNF agents,and IL-1 antagonists.Systems biological understanding of the phosphorylation state in OA synovium is of urgent needs to direct further therapeutic strategies.Therefore,in this study,we compared the synovial phosphoproteome of the OA with the acute joint fracture subjects.We found that OA synovium had significantly more phosphoproteins,and 82 phosphoproteins could only be specifically found in all the OA samples.The differentially expressed proteins(DEPs)of the OA synovium were focused on ER/Golgi-associated secretion and cell proliferation.With an in vitro cell model and data-independent acquisition(DIA)based mass spectrometry,we found that IL-1? could mediate human synoviocytes(HS)to secret proteins,regulating endosomal/vacuolar pathway,ER/Golgi secretion,compliment activation and collagen degradation.Especially,we found that while specifically suppressing HS endocytosis,IL-1? could activate the secretion of 19 TNF down-stream proteins.In conclusion,our results suggest that OA synovium has a polarized phosphoproteome to maintain active secretion of HS,while IL-1? alone can transform HS to produce a synovitis-associated secretome,containing numerous TNF-dependent secretory proteins.