Abstract

Role of microRNAs in regulating TGF-β and IL-10 expression in Human CD8+CD25+CD127 low Regulatory T cells

Author(s): Redouane Rouas, Mohammad Fayyad-Kazan, Makram Merimi, Mehdi Najar, Arsene Burny, Walid Rachidi, Bassam Badran, Philippe Lewalle and Hussein Fayyad-Kazan

Regulatory T cells (Tregs), a population of T cells, are essential for maintaining immune balance and their dysfunction could lead to critical immunological disorders. Tregs are classified as either thymus-derived natural Tregs (nTregs) or adaptive Tregs that are triggered in the periphery in the presence of certain cytokines such as IL-10, and transforming growth factor-β (TGF- β). Treg cells are recognized by expression of FOXP3, a forkhead/winged helix transcription factor 3, and high expression levels of CD25 (the α-chain of the IL-2 receptor). CD8+ T cells represent a major constituent of adaptive immunity. Although CD8+ Tregs with a suppressive function have been identified, the regulatory properties of these cells are still not fully characterized. CD8+CD25+ Treg cells can suppress CD4+CD25− T cells in a manner dependent on their membrane-bound TGFβ and CTLA-4. Moreover, they can secrete certain immunosuppressive cytokines such as TGF-β and IL-10. MicroRNAs (miRNAs), short noncoding single-stranded RNA molecules, that can regulate gene expression post-transcriptionally upon binding to their potential target sites in the 3’ untranslated region (3’UTRs) of specific target mRNA, where they can trigger mRNA degradation and/or repression of protein translation. Nowadays, miRNAs are known to be involved in nearly all biological processes including regulating many aspects of immune responses such as phenotype and function of immune cells. In this study, we aimed at characterizing the miRNA signature of human peripheral blood (PB) CD8+CD25+CD127^low Tregs that has not been described yet. We next addressed the effect of miRNA signature on behavior of those cells.