| Objective: Henoch-Schonlein purpura (HSP) is a common systemic allergic vasculitis in childhood. The clinical manifestations are mainly as non-thrombocytopenic purpura, arthritis or joint pain, gastrointestinal involvement and glomerulonephritis. This disease is more common in children of school age, and the onset of it is more in winter and spring. At present, its pathogenesis is not very clear, many believe that it is not due to a single factor, may be the combined results of individual genetic, environmental factors (such as infection, etc.) and immune abnormalities.Th17 cells, newly discovered T helper cell subsets, can secrete IL-17, IL-22 and other inflammatory cytokines, play an important role in aspects of involved in host defense in bacterial infections, mediated by chronic inflammation, autoimmune diseases and in tumor pathogenesis. Regulatory T cells (Treg), a group of immune suppression and immune regulation cells, have an important role in the body to maintain immune tolerance, immune homeostasis and prevent autoimmune diseases. Retinoic acid-related orphan receptor (ROR)γt is the Th17 cell specific transcription factor, its human homologue is called RORC. RORγt plays an important role in the development of Th17 cell. Their expressions of IL-17 with RORγt deficient CD4+T cells are significantly decreased, while over-expression of RORγt is sufficient to induce the initial CD4+T cells to express IL-17. Forkhead / winged helix transcription factor Foxp3 is specific and over-expression in the regulatory T cell, it plays an important role in the Treg cell differentiation and biological function. Th17 cells and Treg cells are both derived from the initial T cells, and they are interrelated in the differentiation. Changes of the local micro-environment affect initial T cell differentiation, in the presence of transforming growth factor-β(TGF-β), the initial T cells are induced to differentiate into Treg cells, while in the co-presence of TGF-βand IL-6, the initial T cells are induced to differentiate into Th17 cells. At the transcriptional level, transcription factor Foxp3 can bind to the RORγt and inhibit the function of the latter. In addition, the equilibrium state of RORγt and Foxp3 regulated by cytokines determines the cells differentiations to the Treg cells or to the Th17 cells after stimulation by antigen. Under normal circumstances, Th17 cells and Treg cells maintain the balance; it is beneficial to the maintenance of immune homeostasis. Breaking of the balance is a key factor in many autoimmune diseases and inflammation.We applied the real time fluorescence quantitative reverse transcription-polymerase chain reaction (RT-PCR) to detect the expression of RORC mRNA and Foxp3 mRNA in the HSP patient's peripheral blood, to explore the relationship between the key transcription factors controlling of Th17 cells and Treg cell differentiation, to know the HSP patients existing Th17/Treg cells balance or not, and to learn Th17/Treg cells in the pathogenesis of HSP at the transcriptional level.Method: Thirty outpatients of HSP were involved in department of dermatology in the second hospital of Hebei Medical University, males and females were 17 and 13 cases, the average age was (22.60±8.26)years old, course of disease was 2 days to 3 months. 14 cases had a clear history of infection before the onset, 16 cases without a history of infection. Inclusion criteria of the patient group: (1) all the patients with the typical skin purpura, with abdominal pain, joint pain, hematuria or not; the platelet count, function and blood coagulation were normal. (2)Not accompanied with autoimmune diseases, allergic diseases, cancer or other serious systemic diseases. (3)Not used glucocorticoid or other drugs that affect the immune function of the body within 1 month before the test. The control group was involved 15 healthy persons without allergic diseases, autoimmune diseases and family history. The gender and age were not statistically different between the control group and the patient group.Peripheral venous blood was obtained from the patient group and the control group. The expressions of RORC mRNA and Foxp3 mRNA in peripheral blood mononuclear cells (PBMC) were detected by the real time fluorescence quantitative reverse transcription-polymerase chain reaction (RT-PCR). All of the data was analyzed by the statistical package of the SPSS13.0. Student's t test was chosen between the two groups, ANOVA or Kruskal-Wallis H test was chosen among the groups. P <0.05 was statistically significant.Results:1 Gene RORCΔCt value in the HSP group and the control group were 2.00±0.46 and 3.29±1.57,the expression level of RORC mRNA in the HSP group was higher than that in the control group, with a statistical significance (P<0.05).2 Gene Foxp3ΔCt value in the HSP group and the control group were 4.08±1.05 and 4.85±1.52, the expression level of Foxp3 mRNA between the HSP group and the control group was not statistical significance (P>0.05).3 The expression level of RORC mRNA in the HSP with infection history group was higher than that in the HSP with non-infection history group, also higher than that in the control group, with a statistical significance (P<0.05).The expression level of RORC mRNA in the HSP with non-infection history group was higher than that in the control group, with a statistical significance (P<0.05).4 The expression level of Foxp3 mRNA in the HSP with infection history group was higher than that in the control group, with a statistical significance (P<0.05).5 In the HSP patients, the expression level of RORC mRNA and Foxp3 mRNA was not statistical correlation (P>0.05).Conclusion:The expression of RORC mRNA is obviously higher in the HSP patients than the controls, which suggests that the number of Th17 cells may increase, so followed the increasing immune damage factors, the ratio of RORC and Foxp3 mRNA is obviously higher in the HSP patients than the controls, the imbalance of Th17 and Treg cells exists in the HSP, the balance of the inflammation mediated by Th17 and the immune tolerance mediated by Treg is broken, and it may play an important role in the pathogenesis of HSP. The infection factor before the premorbid of HSP significantly affects the expression level of RORC mRNA and Foxp3 mRNA,and it may directly or indirectly contribute to the occurrence of HSP.
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