A study on the function of CD4+CD25+ regulatory T cells in peripheral blood of patients with psoriasis vulgaris.

Abstract

Objective To analyse the function of CD4~+CD25~+ regulatory T cells in patients with psoriasis vulgaris(PV), and try to explore their role in the pathogenesis of PV.Methods Twelve patients with chronic plaque PV, who had a psoriasis area and severity score(PASI)of 15 to 34.5, were included in this study together with 6 healthy human controls.By using immunomagnetic beads, CD4~+CD25~+ regulatory T (Treg)cells and CD4~+CD25~- responder T(Tresp)cells were isolated from peripheral blood of these subjects.Then, these Treg and Tresp cells were subjected to monoculture or coculture under the stimulation with CD3 and CD28.IL-2 was also used to stimulate the proliferation of the Treg cells.[~3H]-thymidine incorporation assay was performed to analyze the proliferation of cells, enzyme linked immunosorbent assay(ELISA)to detect the levels of interferon-gamma(IFN-γ), interleukin-10(IL-10)and transforming growth factor-beta(TGF-β)in the supernatant of monoculture or cocuhure system, and RT-PCR to measure the expression of Foxp3 mRNA.Results After stimulation with CD3 and CD28, neither normal nor psoriatic Treg cells showed obvious proliferation, while this condition was reversed by the addition of IL-2.Cocultured with Tresp cells at a ratio of 1:1,Treg cells inhibited the proliferation of Tresp cells by 60% in the control group and 19.5% in the psoriasis group(P ＜ 0.01).The level of supernatant IFN-γ was 179.66 ± 48.97 ng/L and 109.55± 48.0 ng/L in the monoculture and coculture system of psoriatic Tresp cells, respectively, significantly different from that of control Tresp cells(87.36 ± 33.36 ng/L, 32.55 ± 15.69 ng/L, both P＜ 0.05); the secretion of IFN-γ by Tresp cells was suppressed by 40% in psoriatic group and 63% in control group, by Treg cells(P ＜ 0.05).Treg cells secreted more TGF-β than Tresp cells in the normal control group(3025 ± 769 ng/L vs 2450 ± 431 ng/L, P ＜0.05).Between the patient and control group, there was no statistical difference in the secretion of IL-10 or TGF-β by Treg cells or Tresp cells in monoculture or coculture system(all P ＞ 0.05).In the case of mRNA expression of Foxp3, Treg cells was significantly higher than Tresp cells, whereas no significant difference was observed between psoriatic and control Treg or Tresp cells.Conclusions The impairment of inhibitory function of CD4~+CD25~+ Treg cells leads to an incontrollable proliferation of CD4~+CD25~- Tresp cells in psoriatic patients, which may take part in the pathogenesis of psoriasis. Key words: Psoriasis; CD4~+CD25~+Treg; Cd4~+CD25~-Tresp; Foxp3