The Expression And Pathogenic Mechanism Of Th17Cell In Idiopathic Thrombocytopenic Purpura

Objective: Idiopathic thrombocytopenic purpura (ITP) is a commonacquired hemorrhagic autoimmune disease. The main clinical manifestationsof ITP including the bleeding of skin, mucous membrane, and internalbleeding caused by excessive destruction of platelets. The traditional view isthat the main mechanism of ITP is the production of the autoantibody aimingat the glycoproteins in platelet membrane surface in patients caused byhumoral immune abnormalities. With the development of the pathogenesis ofITP, researchers found that cellular immune abnormalities also played animportant role in the pathogenesis of ITP. The present study confirms that thebalance disorder of Th1(T helper cell1,Th1) cells and Th2cells whichassumes as the dominant of Th1cell response in Th1/Th2cells is one of thepathogenesis of ITP.Th17cells are responsive CD4+T cell subsets discovered in recent yearswhich promote inflammation reactions mainly by specificly secrete IL-17A(interleukin17A，IL-17A). RORγt (orphan nuclear receptor, RORγt) is aspecific transcription receptor that affect the differentiation of Th17cells.RORγt induced the expression of the gene which codes IL-17cell factor.A lot of studies have shown that Th17cells closely related to thepathogenesis of many autoimmune diseases. But there still have controversiesover whether Th17is involved in the pathogenesis of ITP, whether there is arelation between Th17and the imbalance of the ratio of Th1/Th2, or whetherTh17can be used as a standard of assessing the treatment and prognosis of ITP.In this experiment, we tested the expression level of IL-17in serum andIL-17AmRNA, ROR γ t mRNA in mononuclear in peripheral blood in order toassess indirectly the expression level of Th17cells in peripheral blood and toanalyze the relationship and the possible mechanism between Th17cells and the development of ITP. In this study, we also tested the INF-γ（interferonγ，INF-γ）、IL-2、IL-4level in serum to evaluate the Th1/Th2ratio level withINF-γ/IL-4and IL-2/IL-4, in order to further evaluate the correlationbetween three kinds of T cell subsets in the pathogenesis of ITP.Methods: In this study, we collected46ITP patients’ and14relapsepatients’ blood specimens as the experimental group, and35cases of healthyvolunteers as normal control group. Enzyme linked immuno-sorbent assay(ELISA method) is used to detect the concentrations of IL-17A, INF-γ, IL-2,and IL-4in the patients’ plasma in each group, and real-time fluorescencequantitative PCR is used to detect the expression of IL-17A mRNA, ROR γt mRNA.Results:1The levels of plasma IL-17A, and IL-17AmRNA, RORγt mRNA inmononuclear cells of the ITP group and relapse group are higher than that ofthe normal control group before treatment,and with statistical significance(p<0.05). But there was no statistical significance between the ITP group andthe relapse group (P＞0.05).2For the41patients of new cases group and14patients of relapse grouphave achievement of CR after treatment, the levels of plasma IL-17A, andIL-17AmRNA, RORγt mRNA in mononuclear cells before treatment arehigher than that after treatment, and with statistical significance (P<0.05).Forthe5patients of NR cases in the new cases group, we found that there was nostatistical significance in the levels of IL-17A, and IL-17AmRNA, RORγtmRNA.（P>0.05）In accordance with different methods of treatment, we divided the treatedcase into combined treatment group(n=22) and hormones treatmentgroup(n=24). With statistic analysis we found that there was no statisticalsignificance in the levels of IL-17A, and IL-17AmRNA, RORγt mRNA withdifferent methods of treatment（P＞0.05）.3The IL-2, INF-γ levels of cases in new cases and relapse group weredecreased the normal control group before treatment while the IL-4level increased, and the difference was significant (P<0.05). There was no statisticalsignificance in the comparison of that of new cases and relapse group(P＞0.05).4Compare the41patients of new cases group and14patients of relapsegroup,who has achievement of CR after treatment before and aftertreatment,the levels of INF-γ, IL-2decreased after treatment, while level ofthe IL-4increased, were all with statistical significance (P<0.05). But in the5patients of NR cases in the new cases group before and after treatment, therewas no significant difference（P>0.05）.5In plasma of46patients in new cases group before treatment,correlation tests were made between IL-17A level and IL-2, INF-γ, IL-4levels.There was a positive correlation between IL-17A and IL-2, INF-γ and IL-2levels, with statistical significance (P＞0.05), while there was no statisticallysignificant correlation between other factors.6There was no significant difference between male and female patientsin the levels of plasma IL-17A, and IL-17AmRNA, RORγt mRNA inmononuclear cells （PIL-17A=0.409， PIL-17AmRNA=0.091， PROR γ tmRNA=0.193，>0.05）. Verify the correlation between the levels of plasmaIL-17A, and IL-17AmRNA, RORγt mRNA in mononuclear cells and patientage and the blood platelet count (BPC) respectively, there was no significantcorrelation.Conclusions:1Compare the new cases group and the relapse group patients beforetreatment with the normal control group patients, the expression of the levelsof plasma IL-17A, and IL-17AmRNA, RORγt mRNA in mononuclear cellsincreased. While there was no difference between the ITP group and therelapse group patients. It indicated that Th17cells may be involved in thepathogenesis of ITP.2For the therapeutically effective cases in the ITP patients, the levels ofplasma IL-17A, and IL-17AmRNA, RORγt mRNA in mononuclear cellsbefore treatment are higher than that after treatment. With statistic analysis we found that there was no statistical significance in the levels of plasma IL-17A,and IL-17AmRNA, RORγt mRNA in mononuclear cells between combinedtreatment group(n=22) and hormones treatment group(n=24). That indicatesTh17ratio can be used as one of criterions to evaluate the curative effect ofITP after treatment, but could not determine the differences of the effect ofdifferent treatments3The IL-2, INF-γ levels of cases in the ITP group were decreased thenormal control group before treatment while the IL-4level increased, andthere is some recovery of this trend after treatment. It indicated that Th17cellsmay be involved in the pathogenesis of ITP, it assumes as the imbalance ofTh17, Th1, Th2cells subsets, the increasing of Th17, Th1cell ratio, and thedecreasing of Th2cells ratio. The increasing of Th17and Th1exists a positivecorrelation.4This study shows that the expression of IL-17A mRNA, ROR γ tmRNA and plasma IL-17A level in new case ITP have no correlation withgender, age and platelet count.