published_or_final_version / Paediatrics and Adolescent Medicine / Master / Master of Research in Medicine

SLE is a complicated autoimmune disease with a strong genetic basis. Owing to the successful application of genome-wide association study (GWAS) on complex traits, significant progresses have been made in identifying susceptible loci for SLE. So far, more than 30 loci have been shown to have robust association with the disease, significantly improving our understanding of this disease. On the other hand, these loci only confer relatively small increments in disease risk, leaving a large amount of disease heritability unexplained. Several limitations may lead to the issue of “missing heritability”, such as the insufficient statistical power of standard GWAS, the failure to explore independent signals with marginal effects, and other forms of genetic variations or interactions that can hardly be detected by the current GWAS approach. In the current study, efforts have been made on solving the issue of missing heritability. Firstly, in order to increase the statistical power of GWAS, we performed meta-analysis of two existing SLE GWASs on Chinese populations, and replicated the findings in additional samples from Hong Kong, Anhui, and Thailand. We identified ARID5B and CDKN1B as novel SLE susceptibility genes through this approach. Secondly, considering the limitation of previous GWASs that only focus on the most significant signal in an individual region, we revisited the established loci by in-depth analysis on the basis of meta-analysis and followed up the findings with large-scale replication efforts. We found three additional independent signals in 11q23.3 as being associated with SLE. Thirdly, given the importance of independent effects in predisposing disease susceptibility, we performed gene-based analysis to combine the marginal independent signals within a gene to identify novel susceptibility genes. Our results demonstrated the widespread existence of independent effects within known SLE susceptibility genes, and we also identified ANXA6 as a novel SLE susceptibility gene. Lastly, we also made some efforts in the characterization of the related genes, and we identified several regulatory SNPs (rSNPs) predisposing individuals to SLE via affecting expression of the corresponding genes. In addition, we also found that epistatic interaction of variants in a previously established susceptibility gene, ETS1,correlates with cytokine (e.g.IL-17) abnormality in SLE cases. The current work represents several practical approaches to improve the power of GWAS. The findings might enrich the list of SLE susceptibility genes as well as advance our knowledge on the etiology of this complicated disease. Importantly, the current study highlights the importance of independent effects and rSNPs in conferring disease susceptibility, which may shed light on further exploration on the genetic architecture of SLE. / published_or_final_version / Paediatrics and Adolescent Medicine / Doctoral / Doctor of Philosophy

Systemic Lupus Erythematosus (SLE) is an autoimmune disease which is characterized by high level of autoantibody detected in the body. This disease is female predominant with a male to female ratio 1: 9. SLE could cause damage to different organ systems and central nervous system is one of them. Patients diagnosed with SLE could suffer from psychiatric problems like cognitive dysfunction, depression and anxiety. Neurogenesis refers to the process by which new neurons are generated. Although it has been widely reported that neurogenesis could be enhanced under pathological conditions such as stroke, Huntington’s disease and epilepsy, study focusing on the relationship between neurogenesis and SLE remains limited. In the present study, by using NZB/W F1 mice as the animal model of SLE, we could demonstrate that there was dramatic increase of neuronal precursor cells at the corpus callosum after the onset of SLE symptoms. Meanwhile, as IBA-1 positive cells and GFAP positive cells also increased significantly there, this suggested inflammation has taken place. I hypothesized there were upregulation of immunological factors after the onset of SLE symptoms and those factors were responsible for the neurogenesis. In my in vitro study, cytokine- interferon gamma (IFN gamma) has been shown to promote neuronal progenitor cells (NPCs) to differentiate into neuronal linage but it did not obviously affect the cell proliferation and migration. For the other cytokine and chemokines, including interleukin-10 (IL-10), interleukin-8 (IL-8), macrophage-derived chemokine (MDC), stromal cell-derived factor 1 alpha (SDF-1alpha) and thymus and activation regulated chemokine (TARC), all of them had no effect on NPC proliferation and differentiation. As far as we know, this is the first study to report SLE could enhance neurogenesis. Concerning the role of inflammation and IFN gamma on the neurogenesis in our case, it should be worth for further investigation, which will benefit future development of novel treatment targeting psychiatric symptoms in SLE. / published_or_final_version / Anatomy / Master / Master of Philosophy

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the production of autoantibodies against self-antigens. SLE has a complex multifactorial genetic basis. Genome wide association studies (GWAS) have implicated polymorphisms causing decreased expression in many genes in SLE etiology and will likely continue to implicate new genes. Therefore, the aim of my project was to create a modular system where the effect of knocking down a gene of interest can be studied in cell culture in a timely manner. This was accomplished by inserting shRNAmirs targeting our validation gene, A20, into a retroviral vector, creating viral particles using a packaging cell line, and infecting cultured cells. Two shRNAmirs were determined to be effective by qRT-PCR and Western blots on infected cells. Vectors carrying these shRNAmirs were used to infect ex vivo B cells and BMDCs, and results suggested that A20 knockdown may mediate functional changes in both cell types.

Systemic lupus erythematosus (SLE) is an autoimmune disease characterized by the production of autoantibodies against self-antigens. SLE has a complex multifactorial genetic basis. Genome wide association studies (GWAS) have implicated polymorphisms causing decreased expression in many genes in SLE etiology and will likely continue to implicate new genes. Therefore, the aim of my project was to create a modular system where the effect of knocking down a gene of interest can be studied in cell culture in a timely manner. This was accomplished by inserting shRNAmirs targeting our validation gene, A20, into a retroviral vector, creating viral particles using a packaging cell line, and infecting cultured cells. Two shRNAmirs were determined to be effective by qRT-PCR and Western blots on infected cells. Vectors carrying these shRNAmirs were used to infect ex vivo B cells and BMDCs, and results suggested that A20 knockdown may mediate functional changes in both cell types.

Thesis (Ph. D.)--University of Hong Kong, 2008. / Also available in print.

Thesis (Ph. D.)--University of Hong Kong, 2008. / Also available online.

Thesis (Ph.D.) in Biochemistry and Molecular Biology--University of Maine, 2007. / Includes vita. Includes bibliographical references (leaves 121-158).

Thesis (M. Phil.)--University of Hong Kong, 1999. / Includes bibliographical references (leaves 108-130).

Thesis (M.D.)--University of Hong Kong, 1995. / Includes bibliographical references (leaf 172-203).