S100A8 alarmin supports IL-6 and metalloproteinase-9 production by fibroblasts in the synovial microenvironment of peripheral spondyloarthritis.

Introduction: Spondyloarthritis (SpA) is a common autoinflammatory disease. S100A8/ S100A9 alarmin is strongly expressed in the synovial sublining layers of psoriatic arthritis. S100A8/ S100A9 is the most abundant protein in rheumatoid arthritis synovial fluid (SF) and has a key role in promoting IL-6 expression in fibroblast-like synoviocytes (FLS).

Association between IL-17 and IgA in the joints of patients with inflammatory arthropathies.

Background: Hyperactive secretion and pathogenic effects of interleukin (IL)-17 and IgA have been detected in different arthropathies. Recent evidence has revealed that T17 cytokines regulate mucosal IgA secretion. However, it is unknown whether and how IL-17 mediates synovial IgA production.