Research Of The Relationship Between MicroRNA And Aberrant Profile Of T Cells Subsets In Peripheral Blood Of Immune Thrombocytopenia Patients

BackgroundImmune thrombocytopenia (ITP) is an acquired autoimmune disease characterized by accelerated platelet destruction and decreased peripheral platelet count. Although the antiplatelet antibody resulting in over destruction of the platelet may have a major place in the pathophysiology of ITP. the T-lymphocyte mediated immune disturbance and cytotoxicity may also play an important role in its pathogenesis and disease progression. T cells subsets mainly include helper T cells (Thl,Th2,Th17and Th22,etc),regulatory T cells (Treg) and T follicular helper (Tfh) cells and so on. Studies show that the ratios of Th1/Th2, Th17/Treg and Th22are elevated in ITP patients.MicroRNAs (miRNAs) are a novel class of short (21-25nucleotides), non-coding, evolutionary conserved RNAs that widely exist in plants, animals and other eukaryotes. They can regulate post-transcriptional gene expression through incomplete base pairing with the3’-untranslated region (3’-UTR) of target mRNAs to degrade the target mRNAs or inhibit its translation. Studies have confirmed miRNAs may play an important role in innate immunity and adaptive immunity by regulating immune cell differentiation and signal transduction. MiR-181a is a key molecule in modulating signal strength of T cell receptor (TCR). The expression of miR-150is increased during the process of T cell maturation, while it is decreased rapidly in Th1and Th2cells. There are few studies of the relationship between miRNAs and the occurrence or development of ITP.ObjectiveThe purpose of the study is to detect the level of seven immune-related miRNAs (miR-155, miR-146a, miR-326, miR-142-3p, miR-17-5p, miR-21and miR-181a), Th1,Th17,Th22,Treg and antiplatelet antibody in peripheral blood of ITP. Then, we will analyze the correlations of miRNAs expression with T cells subsets, antiplatelet antibody, peripheral platelet count,corticosteroid therapy and clinical indexes, and discuss their relationships in pathogenesis of ITP patients.Methods1. Peripheral blood samples were collected from46initial and recurrent ITP patients (ITP group,19males and27females; age range16-65years; median30). Thirty-nine healthy individuals were served as the control group (17males and22females; age range24-50years; median27).2. The relative expressions of seven miRNAs in peripheral blood mononuclear cell (PBMCs) and plasma were detected by real time polymerase chain reaction (PCR).3. The modified MAIPA assay was used to detect platelet GPⅡb/Ⅲa and GPIb/Ⅸ specific autoantibodies in26ITP patients.4. The percentage of Th1, Th17, Th22or Treg in peripheral was detected by flow cytometry.5. Thirty-one patients responded to corticosteroid therapy, and the relationship between effect and the expressions of miRNAs was evaluated.Results1. The expression levels of miR-146a. miR-326and miR-142-3p in the PBMCs of ITP group were decreased significantly compared to those in the control group (P<0.05).2. In the ITP group, the expression level of miR-146a was positively correlated with miR-326(r=0.605, P<0.001) and miR-181a (r=0.421,P=0.029). The expression level of miR-326was positively correlated with the expression of miR-181a (r=0.720,P<0.001)3. The expression level of miR-146a was positively correlated with the peripheral platelet counts (r=0.658,P=0.0096).4. Thirty-one patients responded to corticosteroid therapy, including23patients in response (R) and8ones in no response (NR). The response rates for therapy were74.19%. The expressions level of seven miRNAs were of no significant difference between the effective group and the ineffective group (P>0.05).5. The percentages of Th22in the ITP group increased significantly compared with the control group (P=0.042), while the percentages of Treg decreased (P=0.004).6. Twenty-six ITP patients were detected the antiplatelet autoantibodies, including13patients in positive autoantibodies,5patients in only one positive autoantibodies and8patients in negative autoantibodies. The expressions level of seven miRNAs were of no significant difference between the different autoantibody groups (P>0.05).7. There were no significant difference in the percentage of Th1, Th17, Th22and Treg cells between the different autoantibody groups (P>0.05).8. There were no significant difference in the peripheral platelet count among the different autoantibody groups (P>0.05).9. In the ITP group, the percentage of Thl was positively correlated with percentage of Th17(P<0.001).10. In ITP group, the expression level of miR-146a was positively correlated with the percentages of Thl, Thl7and Treg cells (P<0.05). Conclusion1. The expression levels of miR-146a, miR-326and miR-142-3p in the PBMCs of ITP patients were decreased significantly.2. The expression level of miR-146a was positively correlated with miR-326and miR-181. The expression level of miR-326was positively correlated with the expression of miR-181a.3. The percentages of Th22increased significantly, while the percentages of Treg decreased in ITP. The percentage of Thl was positively correlated with percentage of Th17.4. The expression level of miR-146a was positively correlated with the peripheral platelet counts.5. The expression level of miR-146a was positively correlated with the percentages of Th1, Th17and Treg cells.In summary, this study confirmed that there were aberrant expressions of miRNAs and T cells subsets in ITP patients. There were correlations between each other. It revealed that they may participate in the occurrence and development of ITP. The three miRNAs may be as the novel targets for ITP, and the relationship between miR-146a and T cells subsets may offer a new clue to recognize the role in pathogenesis and disease progression of ITP.