Peripheral Treg Levels and Transforming Growth Factor-β (TGFβ) in Patients with Psoriatic Arthritis: A Systematic Review Meta-Analysis.

INTRODUCTION

Studies on the level of regulatory T (Treg) cells in psoriatic arthritis (PsA) have been controversial, leading to disagreement regarding the role Treg cells play in the pathogenesis of the disease. To clarify the status of Treg cells in patients with PsA, we performed a meta-analysis to determine the levels of Treg cells and serum Treg-associated cytokines in PsA patients.

METHODS

According to published data from PubMed, Web of Science, Embase, Clinical Trials.gov, MEDLINE, Web of Knowledge, Cochrane Library, and FDA.gov, we determined the Treg and Treg cytokine levels in patients with PsA. The effect estimates were pooled using a random-effects model.

RESULTS

This meta-analysis included 12 studies. Compared to healthy controls (HCs), the proportions of Treg cells had no significant difference in patients with PsA (based on standardized means[SMD] = - 1.038, 95% confidence intervals[CI] =  - 2.165 to 0.089, p = 0.071). On the basis of subgroup analysis, patients with PsA had a lower percentage of CD4+ Treg cells (SMD = - 1.501, 95% CI - 2.799 to - 0.202, p = 0.023) than OKT8+ Treg (SMD = 0.568, 95% CI - 2.127 to 3.263, p = 0.679). Besides, CD4+CD25+FoxP3+ Treg cells and CD4+CD25highCD127low Treg cells were both significantly decreased on the levels of PBMCs in patients with PsA (SMD = - 0.764, 95% CI - 1.404 to - 0.125, p = 0.019; SMD = - 5.184, 95% CI - 6.955 to - 3.412, p < 0.001). CD4+CD25+FoxP3+ Treg cells were particularly more abundant in the synovial fluid thanin peripheral blood (SMD = 3.288, 95% CI 2.127 to 4.449, p < 0.001). No significant difference was observed in the proportion of CD4+CD25+ Treg cells in peripheral blood and CD4+CD25+FoxP3+ Treg cells in CD4+ T cells (SMD = - 2.498, 95% CI - 7.720 to 2.725, p = 0.349; SMD = - 0.719, 95% CI - 2.525 to 1.086, p = 0.435). PsA patients had decreased cytokines such as transforming growth factor-β (TGFβ) (SMD = - 2.199, 95% CI - 3.650 to - 0.749, p = 0.003).

CONCLUSIONS

Treg definition markers influence the scale of Treg cells in patients with PsA. Pathogenesis of PsA may be attributed to an insufficient or malfunctioning Treg population.