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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: BACKGROUND, METHODS, RESULTS. Meshes: Antibodies, Antinuclear, Arthritis, Rheumatoid, Autoantibodies, Humans, Interleukin-17, Mast Cells, Osteoarthritis, Synovial Membrane.
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Are mast cells the main interleukin 17-positive cells in anticitrullinated protein antibody-positive and -negative rheumatoid arthritis and osteoarthritis synovium? Context: Mast cells have been implicated to play a functional role in arthritis, especially in autoantibody-positive disease. Among the cytokines involved in rheumatoid arthritis (RA), IL-17 is an important inflammatory mediator. Recent data suggest that the synovial mast cell is a main producer of IL-17, although T cells have also been implicated as prominent IL-17 producers as well. We aimed to identify IL-17 expression by mast cells and T cells in synovium of arthritis patients. Synovial samples of anticitrullinated protein antibody-positive (ACPA+) and ACPA-negative (ACPA-) RA and osteoarthritis (OA) patients were stained for IL-17 in combination with CD117 (mast cells), CD3 (T cells) and CD68 (macrophages). Concentrations of IL-17 in synovial fluid were determined by ELISA. The number of IL-17+ cells in synovium was comparable in all groups. Although the vast majority of IL-17+ cells are mast cells, no difference in the percentage of IL-17+ mast cells was observed. Nonetheless, levels of IL-17 in synovial fluid were increased in ACPA+ RA patients compared to ACPA- RA and OA patients.
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The synovial mast cell is the main IL-17+ cell in all three arthritis groups analyzed. These data are relevant for studies aimed at blocking IL-17 in the treatment of arthritis. Final Decision: yes