Study On The Role Of Tim-1and Tim-3in The Immune Imbalance Of Patients With Immune Thrombocytopenia

Background and Objective:Immune thrombocytopenia (ITP) is an acquired autoimmune bleeding disorder. The clinical manifestations include skin mucosa bleeding, internal bleeding, and even intracranial hemorrhage, seriously affecting human health. Increasing evidence suggests it is a multifactorial mechanism resulting from immune-mediated platelet destruction and/or suppression of platelet production. Historically, the etiology was attributed solely to the autoantibodies produced by autoreactive B cells against self-antigens. T-cell abnormalities, particularly those related to pro-inflammatory cytokines are considered central in the pathogenesis of ITP. The complex dysregulation of the cellular immunity includes a significant shift toward a T helper (Th)1and Th17pro-inflammatory immune responses of T-cell and cytokine profiles and the decreased number and defected function in CD4+CD25+Regulatory T cells (Tregs). Now studies on T-cell immunoglobulin-and mucin-domain-containing molecule-1(Tim-1) and Tim-3catch more attention regarding its role in the regulation of autoimmune diseases. Tim-1, the first member of the family, as a novel allergy and asthma susceptibility gene, is preferentially expressed on Th2cells but not Thl cells. Tim-1functions as a potent costimulatory molecule for T-cell activation and hyperproliferation. Tim-3is expressed at high levels on polarized Thl cells and at lower levels on Th17cells, functioning as a negative regulator of human T cells and regulates Thl and Th17cytokines secretion. In several human autoimmune diseases, such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA), analysis of Tim-1and Tim-3expression and related cytokines production showed a significant imbalance compared with those from healthy controls, however, the expression of Tim-1and Tim-3in ITP has not been explored. This study aims to explore the role of Tim-1and Tim-3in the pathogenesis of ITP.Methods:(1) Forty-five patients with active disease, thirty-four patients in remission, thirty-one healthy controls were involved in this study. Venous peripheral blood were collected from each patient and control.(2) Seventeen ITP patients spleens and ten controls spleens were enrolled in this study.(3) Mononuclear cells were isolated from venous peripheral blood and spleen. Extract mRNA.(4) Using real-time quantitative polymerase chain reaction, the mRNA expression levels of Tim-1and Tim-3were examined in the peripheral blood mononuclear cells (PBMCs) and spleen mononuclear cells. At the same time, we measured the the mRNA expression levels of the T-box transcription factor (T-bet) and GATA binding protein3(GATA-3).(5) Tim-3on CD4+T cell was assayed by flow cytometry.Results:(1) Tim-1and Tim-3and transcription factor T-bet、GATA3expression in the peripheral blood mononuclear cells (PBMCs) in patients and controls The relative levels of mRNA expression of Tim-1were increased (2.2±1.31) fold in active patients compared with healthy controls (P>0.05) and(1.8±0.97)fold compared with remission patients (P>0.05); The decrease observed in Tim-3expression was (0.27±0.13) fold (P<0.05) and (0.24±0.11) fold (P<0.05) respectively in active patients compared with controls and ITP patients in remission. The ratio of Tim-3/Tim-1in patients with active disease was decreased significantly. The relative levels of mRNA gene expression of T-bet were increased (2.9±1.34) fold in active patients compared with healthy controls (P<0.05) and(2.70±1.14)fold compared with remission patients(P<0.05); GATA-3was down-regulated in active ITP patients and the decrease observed was (0.5±0.22) fold compared with controls(P<0.05) and (0.53±0.16) fold compared with remission patients (P<.05). The ratio of T-bet/GATA3in patients with active disease was increased significantly.(2) Tim-1and Tim-3and transcription factor T-bet、GATA3expression in spleen mononuclear cells in patients and controls The relative levels of mRNA gene expression of Tim-1were increased (3.20±2.18) fold in active patients compared with healthy controls (P>0.05); The decrease observed in Tim-3expression was (0.29±0.16) fold (P<0.05) in active patients compared with controls; The ratio of Tim-3/Tim-1in patients with active disease was decreased significantly. The relative levels of mRNA gene expression of T-bet were increased (2.82±1.57) fold in active patients compared with healthy controls (P<0.05); GATA-3was down-regulated in active ITP patients (0.14±0.10) fold (P<0.05) compared with controls. The ratio of T-bet/GATA3in patients with active disease was increased25-fold compared with healthy controls (.P<0.05).(3)Tim-3expression in CD4+T cells from ITP patients and its correlation with Thl cellsCompared with the healthy controls(mean±SD1.34%±0.13%), the percentage of Tim-3was significantly decreased in the newly diagnosed patients (mean±SD0.77%±0.11%)(P<0.05). A negative correlation was found between the percentage of Tim-3positive cells and the Thl population in ITP patients ’peripheral blood (r=-0.5331, P<.05).Conclusions:(1) Tim-3mRNA expression in PBMCs in newly diagnosed patients was significantly decreased. Meanwhile Tim-1mRNA a trend of elevation.(2) Tim-3mRNA expression in spleen mononuclear cells in newly diagnosed patients was significantly decreased. Meanwhile Tim-1mRNA a trend of elevation.(3) The ratio of T-bet/GATA3in patients with active disease was increased significantly.(4) The reduced levels of Tim-3/Tim-1in PBMCs and spleen mononuclear cells during active stages of the disease suggest a possible role in the pathogenesis and course of ITP.