Regulatory T cell levels and cytokine production in active non-infectious uveitis: in-vitro effects of pharmacological treatment

The aim of this study was to quantify the proportion of regulatory T cells (T-reg) and cytokine expression by peripheral blood mononuclear cells (PBMCs) in patients with active non-infectious uveitis, and to evaluate the effect of in-vitro treatment with infliximab, dexamethasone and cyclosporin A on T-reg levels and cytokine production in PBMCs from uveitis patients and healthy subjects. We included a group of 21 patients with active non-infectious uveitis and 18 age-matched healthy subjects. The proportion of forkhead box protein 3 (FoxP3)(+) T-reg cells and intracellular tumour necrosis factor (TNF)- expression in CD4(+) T cells was determined by flow cytometry. PBMCs were also either rested or activated with anti-CD3/anti-CD28 and cultured in the presence or absence of dexamethasone, cyclosporin A and infliximab. Supernatants of cultured PBMCs were collected and TNF-, interleukin (IL)-10, IL-17 and interferon (IFN)- levels were measured by enzyme-linked immunosorbent assay (ELISA). No significant differences were observed in nT(reg) levels between uveitis patients and healthy subjects. However, PBMCs from uveitis patients produced significantly higher amounts of TNF- and lower amounts of IL-10. Dexamethasone treatment in vitro significantly reduced FoxP3(+) T-reg levels in PBMCs from both healthy subjects and uveitis patients, and all tested drugs significantly reduced TNF- production in PBMCs. Dexamethasone and cyclosporin A significantly reduced IL-17 and IFN- production in PBMCs and dexamethasone up-regulated IL-10 production in activated PBMCs from healthy subjects. Our results suggest that PBMCs from patients with uveitis express more TNF- and less IL-10 than healthy subjects, and this is independent of FoxP3(+) T-reg levels. Treatment with infliximab, dexamethasone and cyclosporin Ain vitro modulates cytokine production, but does not increase the proportion of FoxP3(+) T-reg cells.