Aberrant Expression of MicroRNAs in CD4+ Cells May Contribute to the Imbalance of Th17/Treg Cells in Primary Immune Thrombocytopenia

Backgrounds :Primary immune thrombocytopenia (ITP) is an acquired autoimmune disease characterized by reduced platelet count and an increased risk of bleeding. The imbalance of Treg/Th17 cells has been demonstrated in ITP, but the mechanism of Th17/Treg cells imbalance is still not clear. In this study, we aimed to investigate whether the expression of helper T (Th) or Treg cell-related microRNAs, such as miR-183-96-182 cluster, miR-17-5p, miR-99a, miR-146-5p, miR-155-5p, miR-181-5p, and miR-326, regulates the ratio of Th17/Treg in CD4 + T cells and could be used to evaluate the clinical implications of ITP patients. Methods : Peripheral blood was obtained from 54 patients with active ITP and 34 healthy controls. Peripheral blood mononuclear cells (PBMCs) were isolated using Ficoll density-gradient centrifugation and the CD4 + cells were separated by immuno-magnetic microbeads selection. Amplification technique of RT-PCR using stem-loop primers was applied to detect the relative expression of microRNAs (miR-17-5p, miR-99a, miR-96-5p, miR-146a-5p, miR-155-5p, miR-181a-5p, miR-182-5p, miR-183-5, miR-326) and U6 was normalized as control for miRNA quantification. The frequencies of Th17 and Treg cells in peripheral blood were analyzed by flow cytometry. The mRNA expression levels of Il-6, Il-10, Il-17, Rorγ-t and Foxp-3 in CD4 + cells were determined by RT-PCR. Platelet autoantibodies specific for GPIIb/IIIaor GPIb/IX were measured using MAIPA method. CD4+ cells were transfected with miRNAs (miR-99a, miR-182-5p, miR-183-5), mimics or inhibitors, which were used to detect the function of miRNAs. Cytokines in culture medium were determined by ELISA. Results : Our results showed that the relative expression of miR-182-5p and miR-183-5p in CD4 + cells was significantly increased in active ITP patients, compared to healthy controls (miR-182-5p, median 9.2678 vs 5.2723, p Il-10, Il-17, Rorγ-t and Foxp-3 ) and microRNAs (miR-99a, miRNA-182-5p or miR-183-5p). No significant correlation was found between the microRNAs expression and platelets counts or different autoantibody subsets in ITP patients. The relative expression of other microRNAs (miR-17-5p, miR-96-5p, miR-146a-5p, miR-155-5p, miR-181-5p, miR-326) revealed no difference in CD4 + cells between ITP patients and health controls. Furthermore, the down-regulated expression of miR-183-5p with inhibitors promoted to the differentiation of Th17 cells(Fig. 3a), while up-regulated expression of miR-99a with mimics contributed to Treg cells in CD4 + cells from ITP patients (Fig. 3b). Meanwhile, the IL-17A in culture medium decreased in inhibitor group of miR-183-5p or miR-183-5p. However, miR-182-5p inhibitor had no effect on the differentiation of Th17 cells. Conclusions : Our results show the abnormal expression of microRNAs (miR-99a, miRNA-182-5p and miR-183-5p) in CD4 + cells and the miR-99a was closely correlated with the Treg cells. The aberrant expression of microRNAs may contribute to the imbalance of Th17/Treg cells in the development of ITP patients and potentially constitute a novel therapeutic target. Disclosures No relevant conflicts of interest to declare.