engleski

Synovial tissue macrophages are dominantly alternatively activated in patients with mature osteoarthritis

Background: Macrophages are abundant inflammatory cell type in the synovial membrane of knee osteoarthritis (OA). Their quantity is associated with radiographic severity of knee OA and joint symptoms , while their functions are set in response to micro-environmental signals. Classically activated macrophages M1 support T helper 1 (Th1) driven pro- inflammatory reactions, while alternatively activated macrophages M2 strengthen Th2 inflammatory processes. Objectives: To investigate activation status of synovial tissue macrophages in patients with mature OA in terms of M1 / M2 polarization. Methods: Synovial tissue samples (6) with abundant lymphocyte infiltration were obtained during aloarthroplasty. Double immunofluorescence labeling was performed on paraffin-embedded synovial tissue sections using primary rabbit anti-macrophage CD68 mAb in combination with mouse anti-human antibodies directed toward CD3, arginase-1, TNF-alpha and IL-15. CD206 and CD163 were single labelled. Results: CD68+ macrophages mostly co-expressed arginase-1 (4/6 samples), indicating their M2 orientation. Macrophages were placed in lining synovial tissue and nearby tissue-resident CD3+ cells. M2 markers CD206 and CD163 were found in the area of macrophage interaction with T cells. CD68+ cells co-expressing TNF-alpha or IL-15 M1 markers were in minority in these synovial tissues. Lymphocyte infiltration was less abundant in remaining (2/6) synovial tissue samples. Conclusion: Mature synovial tissue macrophages, equipped dominantly with arginase- 1 are M2 oriented and might support Th2 immune response in surrounding T cells.

Macrophages ; Osteoarthritis ; Synovial membrane ; Arginase-1 ; TNF-alpha

nije evidentirano