Effects Of Micrornas On Behcet's Disease, Vogt-koyanagi-Harada Syndrome And Fuchs Syndrome

BackgroundUveitis, a common cause of blindness in the world, can be due toinfectious or noninfectious mechanism. It has various clinical patterns andcharacteristics in different countries. Behcet's disease (BD) andVogt-Koyanagi-Harada (VKH) syndrome are the two most common uveitisentities in China. It is generally recognized that both diseases are inducedby a complicated interaction, such as environmental factors, autoimmuneresponse and other exogenous elements. Although the etiology of FUS hasnot yet been fully understood, several studies have revealed that both viralinfection and genetic risk factors may be involved in its pathogenesis.Mammalian microRNAs (miRNAs) are small (18-25nt long),endogenous, noncoding RNA oligonucleotides. They are highly conservedduring evolution and have recently emerged as potent regulators of geneexpression linked to most biological function. miRNAsposttranscriptionally regulate gene expression by binding with imperfectcomplementarity to the sequences in the3' untranslated region (3' UTR) of target mRNAs.Based on the background, the present study was designed to explainthe questions as follows:1. Whether these five known immunologicallyrelevant miRNAs (miR-155, miR-146a, miR-326, miR-181a, miR-17)involved in the development of Behcet's disease or VKH syndrome?2.Whether microRNA-146a and Ets-1gene polymorphisms are associatedwith ocular Behcet's disease, Vogt-Koyanagi-Harada syndrome and FuchUveitis syndrome?PartⅠ Effect of microRNA-155on cytokine production bydendritic cells is involved in the pathogenesis of Behcet'sdiseasePurposeMicroRNA (miRNAs) have emerged as a class of gene expressionregulators in the regulation of immunity and mammalian inflammatoryresponse. In the present study, we investigated the role of miRNA inBehcet' disease (BD), an autoinflammatory disease.MethodsMiRNAs expression in peripheral blood mononuclear cells (PBMCs),dendritic cells (DCs) and CD4+T cell were examined using TaqMan real-time PCR. MiR-155mimics and inhibitor were transfected to DCs toevaluate the effects of miR-155on the DC mature and cytokine productionby these cells, and the influence of miR-155-overexpressed DCs on thecytokine production of CD4+T cells. Luciferase reporter assays andWestern blotting were performed to identify the target gene of miR-155.ResultsBD patients with active uveitis showed a significantly decreasedexpression of miR-155in PBMCs and DCs, but not in CD4+T cells, ascompared with normal individuals. Overexpression of miR-155couldinhibit the production of IL-6and IL-1β and promote the expression ofIL-10in DCs. MiR-155transfected DC could significantly inhibitintracellular IL-17expression of allogeneic CD4+T cells when culturedtogether. However, it did not influence the phenotypic DC maturation.Luciferase reporter assays revealed that TAB2was the target gene ofmiR-155. Western blotting results also confirmed this result.ConclusionsThe present results suggest that miR-155expression is decreased inactive BD patients. Downregulated miR-155could be involved in thisdisease through modulating cytokine production of DC and CD4+T cellsby targeting TAB2. Part Ⅱ MicroRNA-146a and Ets-1gene polymorphisms inocular Behcet's disease, Vogt-Koyanagi-Harada syndromeand Fuch Uveitis syndromePurposeMicroRNA-146a (miR-146a) is involved in certainimmune-mediated diseases. Transcription factor Ets-1strongly affectsmiR-146a promoter activity and directly regulates miR-146a expression.This study was performed to investigate the association of miR-146a andEts-1gene polymorphisms with Behcet's disease (BD),Vogt-Koyanagi-Harada (VKH) disease and Fuch Uveitis syndrome (FUS)in a Chinese Han population.MethodsA total of669BD patients,613VKH patients,219FUS patients and1132normal controls were genotyped for miR-146a/rs2910164,ets-1/rs1128334and rs10893872using a PCR restriction fragment lengthpolymorphism assay. miR-146a expression was examined in PBMCs byreal-time PCR. Cytokine production by PBMCs were measured by ELISA.ResultsA significantly decreased frequency of the homozygous rs2910164CC genotype and C allele was observed in BD patients compared with controls(pc=2.19×10~-5, odds ratio (OR)0.61; pc=9.3×10~-5, OR0.75, respectively).MiR-146a expression in GG cases was2.45-fold and1.99-fold respectivelyhigher than that in CC cases and GC cases. There was no association ofrs1128334or rs10893872with BD. There was also no association of thesethree SNPs with its main clinical features. No associations were found withthe three SNPs tested and with its clinical manifestations in VKH disease.IL-17and IL-1β production from rs2910164CC cases was markedly lowerthan that in GG cases. No effect of genotype was observed on the IL-6andMCP-1production and IL-8expression was slightly higher in CC cases.There was no association of these three SNPs with FUS.ConclusionsOur study identified a strong association of rs2910164of miR-146awith BD in a Chinese population and an decreased expression of miR-146aand certain proinflammatory cytokines in individuals carrying the CCgenotype.