Objective: To analyse the distribution of FOXP3+CD25+CD4+ regulatory T cells (Treg) in peripheral blood, synovial fluid and tissue of patients with rheumatic disease during relapse and following local treatment.
Methods: FOXP3 expression was assessed by flow cytometry, immunohistochemistry, immunofluorescence and real-time polymerase chain reaction (RT-PCR). The functional suppressive capacity of Treg was analyzed following co-culture with effector CD4+CD25- T cells through assessment of proliferation and cytokine secretion.
Results: We demonstrate that FOXP3 protein and mRNA expression in synovial fluid T cells was not confined solely to CD25bright T cells as seen in blood, but included CD25intermediate and even CD25neg T cells. Indeed, synovial fluid CD25high T cells showed similar suppressive capacity as CD25bright T cells indicating presence of functional Treg in T cells with lower intensity of CD25. In synovial tissue, FOXP3+ cells were present in low numbers within T cell infiltrates and decreased further following intraarticular glucocorticosteroid administration in parallel with the general reduction in inflammation.
Conclusions: Identification of synovial fluid FOXP3+ Treg with varying intensities of CD25 opens up possibilities for thorough characterization of this important T cell subset in the inflammatory compartment. However, only scarce synovial membrane expression of FOXP3 was found even in the absence of overt inflammation, suggesting that the synovial membrane is a site that would benefit therapeutically from Treg expansion.
Statistics from Altmetric.com
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.