engleski

Macrophages mediate synovial tissue lymphocyte infiltration in patients with mature osteoarthritis

Introduction: Accumulating evidence indicates that chronic, low-grade inflammation plays an important role in the pathogenesis of osteoarthritis (OA), which encompasses all joint structures, including inflammationofthe synovial tissue. The aim o f this study was to investigate the phenotype o f fresh synovial tissue macrophages in terms o f antigen recognition, presentation, polarization, and chemotactic properties. Material and Methods: Paraffin-embedded synovial tissue, freshly sampled during the knee alloarthroplasty, was labelled for CD3, CD56, iNOS, arginase-1 and CCL2 using immunohistology. Double immunofluorescence labelling was performed for CD68 and arginase-1, iNOS, CD3 or CD56. Fresh suspension o f synovial mononuclear cells was obtained by enzymatic digestion and used for flow cytometry analysis of intracellular expression o f arginase-1, iNOS, perforin, granulysin, CCL2, CCL3, CCL17, CCL22 and IL15in CD68+ cells. Surface expression o f pattern recognition receptors (CD206 and CD91), HLA-DR, co-stimulatory molecules and CD16 on CD68+ cells was performed. Results: Freshly isolated synovial tissue macrophages were 90% CD16 negative, barely expressed cytotoxic mediators granulysin and perforin, and produced CCL2 (70%), CCL22 (40%) and CCL3 (20%), whereas CCL17 was negligible. They were surrounded by CD56+ and CD3+ cells in tissue accumulations. In the suspeasion, approximately 15% CD56+ cells expressed IH5 . Average expression o f CD206 and CD91 were approximately 50%, HLA - DR 90%, CD80 30% and CD86 60%. The frequency o f iNOS+ or arginase-l+ CD68+ cells in the suspension was 20%. CD68+ cells on the surface of synovial shoots dominantly expressed arginase-1, while CD68+iNOS+ macrophages were settled in synovial lymphocyte accumulation. Conclusion: The phenotype of synovial tissue macrophages indicates that they may have chemotactic properties towards monocytes and type 2 polarized N K and T cells, according to their tissue distribution and moreover chemokine production. They seem to be able for antigen binding and presentation to T cells and to modulate N K cell activity in terms of their specific phenotype.

osteoarthritis ; macrophages ; synovial tissue

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