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Journal of Diabetes Research
Volume 2016 (2016), Article ID 3694957, 19 pages
http://dx.doi.org/10.1155/2016/3694957
Research Article

Changes of Regulatory T Cells and of Proinflammatory and Immunosuppressive Cytokines in Patients with Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis

1Diabetic Systems Medicine, Guangxi Key Laboratory of Excellence, Guilin Medical University, Guilin 541004, China
2Department of Immunology, School of Basic Medical Sciences, Central South University, Changsha, Hunan 410078, China
3Department of Microbiology, The Chinese University of Hong Kong, Shatin, Hong Kong
4Department of Immunology, Faculty of Basic Medicine, Guilin Medical University, Guilin 541004, China

Received 21 March 2016; Revised 9 August 2016; Accepted 30 August 2016

Academic Editor: Bernard Portha

Copyright © 2016 Yong-chao Qiao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Objective. The aim of this study was to investigate the changes of regulatory T cells (Treg), interleukin-6 (IL-6), IL-10, transforming growth factor-β (TGF-β), and tumor necrosis factor-alpha (TNF-α) in patients with type 2 diabetes mellitus (T2DM). Methods. We performed a comprehensive search up to July 2016 for all clinical studies about the changes of Treg, IL-6, IL-10, IL-17, TGF-β, and TNF-α in T2DM patients versus healthy controls. Results. A total of 91 articles (5642 cases and 7378 controls) were included for this meta-analysis. Compared with the controls (all ), the patients had increased serum levels of IL-6, TGF-β, and TNF-α but decreased the percentage of peripheral CD4+CD25+Foxp3+Treg and serum IL-10 level. Furthermore, the percentage of peripheral CD4+CD25+Foxp3+Treg () and serum IL-10 level () were significantly lower in the patients with complication and in the patients without complication, respectively. No significant changes about the percentage of CD4+CD25+Treg () and serum IL-17 level () were found in T2DM patients. Conclusions. T2DM patients have decreased the percentage of peripheral CD4+CD25+Foxp3+Treg and levels of serum IL-10 but elevated serum levels of IL-6, TGF-β, and TNF-α. Presence of diabetic complications further lowers the peripheral CD4+CD25+Foxp3+Treg number.