No description available.

published_or_final_version / Pathology / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / toc / Medicine / Master / Doctor of Medicine

published_or_final_version / abstract / Medicine / Doctoral / Doctor of Philosophy

Systemic lupus erythematosus (SLE) is characterized as an autoimmune disorder with unclear etiology. To identify the genetic effect of SLE, a genome wide association study (GWAS) and its further replication were conducted on SLE patients in Asian populations and ethnically matched controls. Before this study, most of the confirmed association loci were identified by GWAS studies in European populations. Apart from the established associations, we identified a SLE susceptible single nucleotide polymorphisms (SNP) located in ETS1 (rs1128334, P=2.3E-11, OR=1.29) in four different cohorts. This locus is probably an Asian-specific susceptibility locus since no Caucasian study has reported further validation in the last years. A new susceptibility variant in UHRF1BP1 (rs13205210, P=4.4E-09, OR=1.49) independent from the previously confirmed SNPs in Caucasian study was also confirmed to be associated with SLE in the Hong Kong Chinese population. Meta-analysis was performed by introducing another Chinese Han GWAS data set from Anhui province, China. Three loci, TET3-DGUOK, CD80, DRAM1, were confirmed to be associated with SLE. Two loci with suggestive signals in Hong Kong GWAS and further replication were also confirmed by the meta-analysis: PTTG1-MiRNA146a, YDJC. In order to identify the genetic effect for females who have predominant chance to suffer from SLE, X chromosome specific meta-analysis based on the Hong Kong and Anhui GWAS data and further replication study were performed by considering the difference between females and males. A signal in PRPS2, and three independent signals in the Xq28 were confirmed with the replication in three different cohorts by considering both females and males. Gene-gene interactions were also investigated genome-widely in a hypothesis free manner based on the meta-analysis results. The further validation processes were preceeded based on each independent GWAS data set. Four pairswise interacting loci were found and cross validated by three methods including logistic regression and Multifactor Dimensionality Reduction (MDR) and information gain theory based on the Anhui GWAS data set. Further studies are still needed to better explain the real features of genetic epistasis and the potential biological roles. By incorporating two GWAS from the same population, the population difference is efficiently avoided. Together with the putative gene-gene interactions, this study presents a comprehensive analysis based on the GWAS data conducted on SLE. It may shed new light on the disease mechanisms of SLE. / published_or_final_version / Paediatrics and Adolescent Medicine / Doctoral / Doctor of Philosophy

abstract / Medicine / Doctoral / Doctor of Philosophy

No description available.

No description available.

No description available.

O lúpus eritematoso sistêmico (LES) é uma doença inflamatória crônica autoimune que se caracteriza pela perturbação da homeostase imunológica. Envolve a indução e produção de autoanticorpos, bem como formação e deposição de complexos imunes, que conduzem a uma intensa resposta inflamatória e dano tecidual. Fatores imunológicos, ambientais, hormonais e genéticos podem estar implicados na patogênese da doença. A expressão alterada de genes e proteínas reguladores da apoptose em células T pode comprometer a tolerância imunológica e induzir autoantígenos responsáveis pelo desenvolvimento e perpetuação de condições autoimunes. Mas, pouco se sabe a respeito de como a expressão destas proteínas afeta o desenvolvimento e a função das células T. As células T regulatórias (Treg), uma subpopulação celular de importância para prevenir a autoimunidade, apresentam número e capacidade supressora alterados nos pacientes lúpicos. Buscando entender como anormalidades observadas nas vias apoptóticas contribuem para a autoimunidade, o presente estudo avaliou a frequência de apoptose inicial e morte celular de linfócitos nestes pacientes, a frequência de subtipos de células T expressando as proteínas envolvidas nas vias extrínseca e intrínseca da apoptose, como Fas, FasL, Bax, Bcl-2 e p53, além da expressão dos genes que as codificam. Analisou-se ainda a frequência de polimorfismos nos genes FAS, FASL, BCL-2 e BAX em pacientes, comparando estes dados com o de controles, buscando possíveis associações com a predisposição à doença e com os dados clínicos. Foram estudados 427 pacientes com LES do Hospital de Clínicas de Porto Alegre (HCPA) e 543 indivíduos saudáveis, como controles. Dados de 50 mulheres lúpicas mostraram maior frequência de células Treg, bem como maior densidade de expressão do fator de transcrição Foxp3 nestas células em relação a controles, embora não tenhamos observado diferenças estatísticas em relação à expressão de proteínas pró- e antiapoptóticas nesta subpopulação celular. Uma proporção aumentada de células T CD4+ expressando Fas e p53, e uma frequência reduzida expressando Bcl-2 foi encontrada nas pacientes, em relação aos controles. Esse último dado foi apoiado pela relação observada entre a menor frequência de T CD4+ expressando Bcl-2 e a atividade da doença, e pela expressão diminuída do gene BCL-2 em células mononucleares do sangue periférico (PBMCs) de mulheres lúpicas. Células T CD8+ expressando Bax e p53 também foram mais frequentes nas pacientes, ressaltando que células T CD8+p53+ foram mais numerosas nas pacientes com positividade para anticorpos anti-DNA. Maior frequência de morte de linfócitos foi observada em mulheres lúpicas. Com relação ao estudo dos polimorfimos, variantes alélicas dos genes FASL e BAX possivelmente se relacionam com o desenvolvimento e proteção da doença, respectivamente. Em conclusão, nossos achados apontam que a expressão modificada de genes e proteínas em células TCD4+ e TCD8+, relacionada a uma maior taxa de apoptose, podem conduzir à desregulação das vias apoptóticas e levar à perda da tolerância periférica, favoráveis ao desenvolvimento do LES. / Systemic lupus erythematosus (SLE) is a chronic inflammatory autoimmune disease that is characterized by disruption of the immune homeostasis. It involves the induction and production of autoantibodies, as well as formation and deposition of immune complexes, leading to a severe inflammatory response and tissue damage. Immunological, environmental, hormonal and genetic factors may be implicated in the pathogenesis of the disease. The altered expression of genes and proteins regulating apoptosis on T cells may lead to breakdown of the immune tolerance and induce autoantigen responsible for the development and perpetuation of autoimmune conditions. Little information is known of how these proteins affect the development and function of T cells. Regulatory T cells (Treg), a cell subpopulation of importance to prevent the autoimmunity, exhibit changed number and suppressive capacity in SLE patients. Trying to understand how abnormalities observed in apoptotic pathways contribute to autoimmunity, the present study evaluated the frequency of initial apoptosis and cell death of lymphocytes in these patients, the frequency of T cell subsets expressing the proteins involved in the extrinsic and intrinsic pathways of apoptosis, such as Fas, FasL, Bax, Bcl-2 and p53, besides the expression of genes that encode them. We also examined the polymorphisms frequencies of Fas, FasL, Bcl-2 and Bax genes in patients, comparing these data with controls, looking for possible associations with the predisposition to disease and the clinical data. 427 SLE patients from Hospital de Clínicas de Porto Alegre (HCPA) and 543 healthy subjects, as controls were studied. Results from 50 SLE women showed a higher frequency of Treg cells as well as a higher density of Foxp3 expression in these cells compared to controls, although we have not observed statistical differences in relation to the expression of pro- and antiapoptotic proteins in this cell subpopulation. An increased proportion of CD4+ T cells expressing Fas and p53, and a reduced frequency expressing Bcl-2 were found in patients. The latter finding was supported by the negative relation found between the frequency of CD4+Bcl-2+ cells and the disease activity index and by the decreased expression of BCL-2 gene in PBMCs of lupus women. CD8+ T cells expressing Bax and p53 were also more frequent in patients, noting that CD8+ T cells expressing p53 were more frequent in patients positive for anti-DNA antibodies. A higher frequency of death of lymphocytes was observed in SLE women. Regarding to polymorphisms analysis, allelic variants of FasL and Bax are possibly relate to the development and protection of the disease, respectively. In conclusion, our findings indicate that the modified expression of genes and proteins in CD4+ and CD8+ T cells, related to an increased apoptosis, may lead to dysregulation of the apoptosis pathways and the loss of peripheral tolerance, favorable for SLE development.