Objective: The aim of this study was to investigate the turnover of Treg cells in the SF of RA patients.
Methods: Treg cells were enumerated in peripheral blood and SF of RA patients and analysed by flow cytometry for expression of the proliferation marker Ki-67 and binding of the apoptosis marker annexin V. Sorted Treg cells of RA patients were analysed for expression of anti-apoptotic regulators Bcl-2 and microRNA-21 (miR-21) by RT-PCR.
Results: Treg cells displaying a memory phenotype were abundant in the SF of RA patients. SF Treg cells more frequently expressed the proliferation marker Ki-67 than conventional T cells. Only few SF Treg cells were apoptotic, as indicated by limited annexin V staining of these cells. SF Treg cells displayed high transcription levels of Bcl-2 and miR-21 in comparison with SF conventional T cells and peripheral blood Treg cells.
Conclusion: Treg cells with a memory phenotype accumulate in the SF of RA patients. These Treg cells have a high proliferative activity and demonstrate little apoptosis. The latter finding could be explained by high transcription of Bcl-2 and miR-21 in SF Treg cells.
Keywords: Bcl-2; apoptosis; cell proliferation; miR-21; microRNA; regulatory T cell; rheumatoid arthritis.
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