Correlation of interleukin 6 and transforming growth factor β1 with peripheral blood regulatory T cells in rheumatoid arthritis patients: A potential biomarker

Abstract

Introduction: Proinflammatory cytokines and regulatory t cells (TREGS) are considered as important factors involved in autoimmunity development especially in rheumatoid arthritis (RA). Aim of the study: to investigate the frequency of peripheral blood tregs and related cytokines in ra patients and to determine the possible correlation between treg percentage and interleukin 6 (il-6) and transforming growth factor β1 (tgf-β1) as indicators in assessment of treg function and mechanisms preceding autoimmunity in ra. Material and methods: thirty-seven iranian ra patients with a moderate (3.2-5.1) disease activity score (DAS) and the same number of healthy age- and sex-matched individuals were enrolled. frequency of peripheral blood tregs (Cd4+foxP3+Cd25high) was determined by flow cytometry. serum levels of il-6 and tgf-β1 and their expression levels in peripheral blood mononuclear cells (PBMCs) were evaluated by elisa and Q-PCR, respectively. Results: rheumatoid arthritis patients showed significantly lower peripheral blood treg frequencies compared to healthy individuals. additionally, treg (%) showed a significant inverse correlation between serum concentrations of il-6 and mRNA expression of PBMCs, whereas there was no significant correlation between treg (%) and tgf-β1 levels. Conclusions: the current study revealed that treg numbers were reduced in peripheral blood of ra patients. this reduction inversely correlated with il-6 levels, which may lead to persistent autoimmune and inflammatory conditions in ra patients.