published_or_final_version / Paediatrics and Adolescent Medicine / Master / Master of Philosophy

published_or_final_version / abstract / Pathology / Doctoral / Doctor of Philosophy

published_or_final_version / Paediatrics and Adolescent Medicine / Doctoral / Doctor of Philosophy

No description available.

Tang, Xiaolin. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 132-144). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Lupus is a complex, poorly understood long-term disease in which the body's immune system mistakenly attacks healthy tissues of any part of the body. The disease mainly affects young women of childbearing age. Studies from developed countries show that the condition affects individuals physically, emotionally and socially. However, nothing is known about how having lupus has affected individuals living with the condition in the African continent. I explored how lupus had affected individuals living with the condition in Kenya from the time individuals began to feel unwell. I interviewed three groups of participants. 10 individuals who attended the public rheumatology clinic, 11 individuals who attended a private rheumatology clinic and 6 doctors who worked in the rheumatology clinics. The study found that some individuals delayed in getting medical help for their lupus. It appears to take a long time for individuals to get their lupus diagnosed due to organisation and staffing of the Kenyan health system. It was also perceived by individuals with lupus that treatment for the condition was difficult to access and it was also costly. Some individuals believed that their lupus had a supernatural cause. Often there appeared to be a lack of understanding of lupus by individuals who suffered from the condition; and also by others, some having experienced disapproval or negative feelings from others. Individuals with lupus reported lacking the financial resources and social support to manage their condition better. Lupus was affecting them physically, emotionally and had an impact on their social lives. There are a number of challenges in living with lupus in Kenya, including individuals' and others perception of the condition, but also how healthcare is provided to these individuals.

Systemic lupus erythematosus is an autoinflammatory disorder driven by the development of autoantibodies to self-nucleic acids, in particular to DNA and to chromatin. Loss-of-function mutations of the secreted deoxyribonuclease DNASE1L3 have been implicated in the development of aggressive familial lupus. In addition, recent genome-wide association studies have linked a hypomorphic variant of DNASE1L3 to sporadic lupus. Studies in the lab determined that Dnase1l3-deficient mice develop rapid autoantibody responses against dsDNA and chromatin, and at older ages this leads to a lupus-like inflammatory disease. These disease manifestations were completely independent of the intracellular DNA sensor STING, which has been implicated in other examples of self-DNA driven autoinflammatory diseases. My project focused on developing assays to track the activity of DNASE1L3, as well as identifying the endogenous source of self-DNA normally processed by DNASE1L3. Using mouse models that allow the depletion of specific cell populations, we found that circulating DNASE1L3 is produced by hematopoietic cells, in particular by CD11c+ dendritic cells and by tissue macrophages. Taking into account the unique properties of DNASE1L3, we discovered that this enzyme is uniquely able to digest chromatin contained within and on the surface of apoptotic microparticles. Loss of DNASE1L3 activity in circulation results in elevated levels of DNA in plasma, in particular within microparticles. Microparticles are extensively bound by anti-chromatin autoantibodies isolated from both murine models of lupus as well as prototypical human clones. In addition, Dnase1l3-deficient mice have high levels of circulating IgG that bind to microparticles from young ages, and these titers increased as disease progressed in aged animals. Pretreatment of microparticles with DNASE1L3 largely abrogated this binding, demonstrating that DNASE1L3 directly reduces the immunogenicity of microparticles. We also studied two human patients with null mutations in DNASE1L3, and observed increased DNA circulating in plasma and, in particular, in their microparticles, demonstrating a conserved role for DNASE1L3 in mice and humans. Finally, we obtained plasma samples from a cohort of patients with sporadic SLE, and found that roughly 80% had circulating IgG that avidly bound microparticles. Roughly half of this group failed to bind to microparticles that had been pretreated with DNASE1L3, and this DNASE1L3-sensitive group also presented with lower levels of DNASE1L3 activity. We conclude that extracellular chromatin associated with microparticles acts as a potential self-antigen capable of causing loss of tolerance to self-DNA and inflammatory disease in both mice and humans. The secretion of a DNA-processing enzyme thus represents a novel, conserved tolerogenic mechanism by which dendritic cells restrict autoimmunity.

Introdução: A prolactina (PRL) exerce efeitos imunoestimulatórios in vitro e in vivo, porém a literatura é controversa quanto ao papel deste hormônio na atividade do Lúpus Eritematoso Sistêmico (LES). A macroprolactina possui menor atividade biológica in vivo e poderia explicar os resultados díspares. Objetivos: avaliar a prevalência de hiperprolactinemia e macroprolactinemia em pacientes lúpicas; analisar a correlação entre a atividade do LES e PRL, e interferência da macroprolactina nesta associação. Casuística e Métodos: Em 73 mulheres com LES ativo foi dosada a PRL pelo Immulite 2000®, e a macroprolactina pelo método do Polietilenoglicol (momento 1); em 62 destas pacientes foi colhida uma segunda amostra com a menor atividade do LES ao longo do tratamento (momento 2). Os controles foram 29 mulheres hígidas no menacme (grupo C) e 34 gestantes no terceiro trimestre (grupo G). Resultados: Houve 15 casos (20,55%) de hiperprolactinemia nas lúpicas, e nenhum entre as mulheres hígidas (p = 0,005). Todas as gestantes apresentaram hiperprolactinemia. A concentração de PRL foi maior (Med = 11,70 ng/ml) (p = 0,01) no LES do que no grupo C (Med = 8,81ng/ml), e correlacionou-se com a atividade da doença pelo SLEDAI (r = 0,41; p = 0,0003) no momento 1. No LES muito ativo os níveis de PRL foram maiores do que na doença inativa (Med = 17,10 ng/ml vs. Med = 8,36 ng/ml) (p< 0,01), e moderadamente ativa (Med = 7,75 ng/ml) (p < 0,05). Dentre as lúpicas hiperprolactinêmicas, 04 casos (26,7%) foram devidos à macroprolactina, e nas gestantes, 02 casos (5,9%). O LES foi tão ativo na macroprolactinemia quanto nos casos pela forma monomérica, porém a correlação entre PRL e SLEDAI foi maior para a PRL livre (r = 0,44; p = 0,0001). O tratamento das pacientes lúpicas hiperprolactinêmicas resultou em diminuição da concentração de PRL (Me momento 1 = 56,71 ± 43,87 ng/ml vs. Me momento 2 = 18,68 ± 24,20 ng/ml) (p = 0,015). Conclusões: pacientes lúpicas apresentam hiperprolactinemia mais frequentemente do que mulheres hígidas, e a PRL correlaciona-se com a atividade do LES. A macroprolactinemia não é marcador de doença inativa/pouco ativa. / Introduction: Prolactin (PRL) is a hormone with widespread influences in the cells of the immune system, which have been demonstrated by several in vitro and in vivo studies. However, the role of this hormone in the pathogenesis of Systemic Lupus Erythematosus (SLE) is controversial within the medical literature. The potentially lower biological activity of macroprolactin could explain the disparity of the results. Methods: PRL levels were determined by chemo luminescence method (Immulite 2000®) in 73 women with active SLE (group L), while the screening for macroprolactinemia was determined by the polyethylene glycol precipitation method (first moment). Sixty two of these patients had their PRL levels determined in a second occasion, when the disease was inactive or with the lowest activity observed after treatment (second moment). The control groups were 29 healthy women (group C) and 34 third-trimester healthy pregnant (group P). The levels of PRL were correlated with the SLE Disease Activity Index (SLEDAI). Results: In the study group there were 15 (20.55%) cases of hyperprolactinemia, while in the group C there were none (p = 0,005). All pregnant women presented hyperprolactinemia. Prolactin levels were higher in group L (Med = 11,70 ng/ml) then in group C (Med = 8,81ng/ml) (p = 0,01) and correlated with the SLEDAI in the first moment (r = 0,41; p = 0,0003). We also detected that PRL levels were higher at highly active SLE (SLEDAI ¡Ý 11) than when the disease was inactive (SLEDAI = 0) (Med = 17,10 ng/ml vs. Med = 8,36 ng/ml) (p< 0,01) or moderately active SLE (6 ¡Ü SLEDAI ¡Ü 10) (Med = 7,75 ng/ml) (p<0,05). In the 15 patients of group L with hyperprolactinemia, there were 04 cases of macroprolactinemia (26.7%), while 02 subjects in group P presented it (5.9%). SLE was as active in the patients with hyperprolactinemia caused by the monomeric form of the hormone, as in the ones with macroprolactinemia. The correlation of the PRL levels and the SLEDAI was, nevertheless, stronger for free PRL (r = 0,44; p = 0,0001). The SLE treatment in the hyperprolactinemic patients reduced PRL levels from 56,71 ng/ml (sd = 43,87) to 18,68 ng/ml (± 24,20) (p = 0,015). Discussion: the frequency of hyperprolactinemia is higher in SLE than in the general population, and the levels of PRL correlate with the activity of the disease. Macroprolactin is also associated to active SLE.

Systemic lupus erythematosus (SLE) is a relatively rare autoimmune disease with no known aetiology or cure. In addition to numerous physical symptoms, those living with SLE have also been shown to experience significant emotional and psychosocial difficulties. There has been little psychological research into SLE despite the rapidly increasing interest in health psychology and quality of life issues over the last two decades. One such issue that has commanded particular attention is that of cognitive bias in individuals with chronic pain and/or chronic illness. Cognitive bias toward illness-related information is theorised to indicate the presence of an illness self-schema, and is a valuable tool of investigation as it permits access to a level of cognitive structure that is inaccessible via self-report instruments. The primary focus of the present study is to investigate recall bias for pain- and illness-related words in SLE patients. This bias is explored relative to the recall of neutral words and depression-related words, and also relative to the responses of rheumatoid arthritis (RA) patients and healthy controls. Two hypotheses are proposed: firstly, that bias is related to disease activity; and secondly, that bias is related to the combination of illness and depression. The findings provide support for the second hypothesis, with the additional caveat that the nature of the pain/illness stimuli used is important in determining the presence of cognitive bias. No recall bias for illness-related words as a whole was found in any of the groups, nor was there evidence of a recall bias in the SLE and RA patients when they were divided according to depression status. However, when the illness words were examined separately according to �sensory pain� and �disability-related� words, a clear bias for disability words was found in the depressed patient group. It is concluded that there is a relationship between depression in chronically ill individuals, and the way in which such individuals process disability-related words. In accordance with the schema-enmeshment model (Pincus & Morley, 2001), it is suggested that both a pain-schema and an illness-schema exist, and it is when these two schemas become enmeshed with the self-schema that depression occurs in chronic pain/chronically ill patients. The cognitive bias assessment paradigm adopted in this study-one that is typically used in similar investigations-is lengthy, requires sophisticated equipment and can be difficult to interpret on an individual level. The present study investigates the relationship between cognitive biases in SLE patients and a recently-developed task, PRISM, which appears to symbolise the enmeshment of illness-, pain- and self-schemas. Analyses confirmed that recall of negative illness words was the only independent predictor of PRISM scores. This suggests that PRISM, a quick and easy task to administer, may have considerable usefulness as a clinical tool to assess information relevant to the enmeshment of illness- and self-schema. A greater understanding of schema and the processing styles of chronically ill patients will allow for more effective psychological treatment such that quality of life can be improved.

Thesis (M. Phil.)--University of Hong Kong, 2005. / Title proper from title frame. Also available in printed format.