The proportion and phenotypic changes of CD4+CD25-Foxp3+ T cells in patients with untreated rheumatoid arthritis

Abstract

Objective: CD4⁺CD25⁺Foxp3⁺ regulatory T (Treg) cell-mediated immunosuppression is an essential mechanism of rheumatoid arthritis (RA). However, little is known regarding the specific role of CD4⁺CD25^-Foxp3⁺ Treg cells in RA. This study aimed to investigate the frequency of circulating CD4⁺CD25^-Foxp3⁺ Treg cells and their role in RA.

Methods: Sixty-one untreated RA patients and 40 healthy controls (HCs) were enrolled in this study. The proportion of CD4⁺CD25^-Foxp3⁺ T cells and CD4⁺CD25⁺Foxp3⁺ Tregs; the levels of CTLA4, GITR, Helios, and ICOS; and the production of IL-17A, IFN-γ, and IL-10 were assessed by flow cytometry. The correlation of CD4⁺CD25^-Foxp3⁺ T cells and CD4⁺CD25⁺Foxp3⁺ Tregs with the clinical indicators was conducted by Spearman correlation analysis.

Results: The proportion of CD4⁺CD25^-Foxp3⁺ T cells was elevated in RA and positively correlated with disease activity. CD4⁺CD25^-Foxp3⁺ T cells expressed less Helios and produced more IFN-γ than conventional Tregs in RA. Additionally, the proportion of CD4⁺CD25^-Foxp3⁺ T cells was positively correlated with DAS28 score, IgG titer, and anti-CCP titer.

Conclusions: These data indicate that CD4⁺CD25^-Foxp3⁺ T cells in RA exhibit several different functional properties from conventional Tregs and are correlated with RA disease activity.

Keywords: CD4+CD25+Foxp3+ T cells; CD4+CD25−Foxp3+ T cells; Disease activity; Phenotypic; Rheumatoid arthritis.

Fig. 1

Elevated proportions of CD4+CD25-Foxp3+ T cells and CD4⁺CD25⁺Foxp3⁺ Treg cells in RA: a representative flow cytometry plots. b The proportion of CD4⁺CD25⁻Foxp3⁺ T cells in the PB of HCs, total untreated RA patients, inactive RA patients, and active RA patients. c The proportion of CD4⁺CD25⁺Foxp3⁺ Treg cells in the PB of HCs, total untreated RA patients, inactive RA patients and active RA patients. *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001. HCs, healthy controls; RA, rheumatoid arthritis.

Fig. 2

The correlation between the proportions of CD4⁺CD25⁻Foxp3⁺ T cells and CD4⁺CD25⁺Foxp3⁺ Treg cells and clinical variables. a, b The Spearman rank test was used to analyse the correlation between the CD4⁺CD25⁻Foxp3⁺ T cells or CD4⁺CD25⁺Foxp3⁺ Treg cells and DAS28-ESR, IgG titer, IgM titer, and anti-CCP titer.