Thèse d'exercice : Médecine. Médecine interne : Université de Nantes : 2003. / Bibliogr. f. 44-54 [143 réf.].

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 228-261). Also available in print.

Inaug.-Diss.--Amsterdam. / "Litteratuurlijst": p. 168-171.

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (p. 202-219). Also available in print.

published_or_final_version / Medicine / Doctoral / Doctor of Philosophy

Systemic lupus erythematosus (SLE) is an autoimmune disease with diverse manifestations affecting multiple organs. Current understanding of its pathogenesis remains largely inadequate despite recent progress in SLE research on the characterization of immune system dysfunction and its link with heritable and environmental factors. Dendritic cells (DCs) are immune cells that express pattern recognition receptors (PRRs) for the recognition of pathogen associated molecular patterns (PAMPs). Aberrant functions of DCs have been reported in SLE including recognition of self-nucleic acids, presentation of self-antigens and strong induction of interferon response, depending on their expression of PRRs. Dectin-1 is a non-toll like receptor PRR that is highly expressed in DCs for the recognition of pathogenic carbohydrates found mostly in fungi. Recognition of fungal carbohydrates by dectin-1 promotes DC maturation and production of pro-inflammatory cytokines that preferentially skew towards a T helper-17 (Th17) response which has been found to be engaged in the pathogenesis of SLE and other autoimmune diseases. Therefore, the current investigation aimed to study the expression of dectin-1 and the effect of dectin-1 activation in DCs from SLE patients. Dectin-1 expression on CD14+ monocytes from peripheral blood of SLE patients and healthy controls was measured by flow cytometry. SLE patients (mean+/-SD = 92.05+/-3.471%) were found to have higher dectin-1 expression on CD14+ monocytes compared to controls (mean+/-SD = 83.7+/-14.64%) (p=0.02). Monocyte derived DCs (MoDCs) were then derived from CD14+ monocytes in the presence of granulocyte macrophage-colony stimulating factor (GM-CSF) and interleukin (IL)-4. Pre-treated moDCs with curdlan, a dectin-1 specific ligand, showed increased expression of costimulatory molecules including CD83 and CD86 and enhanced production of IL-1β compared with healthy controls (all p<0.05). Curdlan treated moDCs were further co-cultured with CD4+ na?ve T cells and polarization into Th17 cells was subsequently evaluated by measuring the percentage of Th17 per moDCs-na?ve T cells and expression of intracellular IL-17. Curdlan treated moDCs from SLE patients were found to have enhanced Th17 polarization capacity (mean+/-SEM = 28.33+/-5.64%) compared with controls (mean+/-SEM = 12.77+/-2.56%) (p<0.05). To address the mechanism of Th17 polarization, expression of caspase-1 which promotes the production of IL-1β was measured. Curdlan treated moDCs in SLE patients expressed higher levels of caspase-1 detected in the cell lysate as measured using Western Blot compared with healthy controls (p<0.05). In conclusion, compared with healthy individuals, SLE moDCs were more matured and activated in response to β-glucan as shown by their higher expression of co-stimulatory molecules, enhanced production of IL-1β and stronger Th17 polarizing effect. These findings suggest functional dysregulation of dectin-1 expressing DCs in patients with SLE which may be involved in the pathogenesis of this condition. / published_or_final_version / Medicine / Master / Master of Philosophy

Subsets of systemic lupus erythematosus (SLE) patients with distinct patterns of disease manifestations and autoantibody production have been reported, but seldom have these two phenomena been analysed together. Cluster analysis was performed on 1928 Chinese SLE patients based on autoantibody profile and the frequencies of various clinical manifestations were compared between each cluster. Separate association analyses between individual autoantibodies and clinical manifestations, as well as between clinical manifestations, were also performed. This study identifies three separate autoantibody clusters each with different clinical manifestations, and proposes that the phenomena of autoantibody clustering and clinical subsets may be inter-related. Patient clusters could also be stratified into a bipolar spectrum. On one end are patients with over-representation of anti-dsDNA and renal disorder; whilst on the other end are two distinct autoantibody clusters (anti-Sm/anti-RNP/aPL and aPL/anti-Ro/anti-La) with overlapping of other non-renal manifestations. Patient stratification could aid disease prediction and subsequent management. These findings may also elucidate disease pathogenesis and guide future study on potential common pathological processes within autoantibody clusters. / published_or_final_version / Paediatrics and Adolescent Medicine / Master / Master of Research in Medicine

Systemic lupus erythematosus (SLE) is a chronic autoimmune disorder that brings physical and psychological turmoil to patients. Neuropsychiatric (NP) involvement in SLE also complicates disease management compared with non-NP SLE. The joint pain caused by the dysfunctional inflammatory response, as well as the negative mood induced by the disease have been found to predict the patients’ quality of life. The primary goal of this study is to examine the mediation effect of negative mood on the relationship between pain and quality of life in patients with SLE based on a biopsychosocial approach. Results revealed that negative mood partially mediated the relationship between pain and the physical aspect of quality of life. On the other hand, negative mood completely mediated the relationship between pain and psychological health. The mediation relationship lends support to the biopsychosocial perspective that physical distress, psychological state, and one’s adaptive functioning are closely related. The secondary goal of this study is to explore the effect of NP involvement in patients with SLE on self-report variables, including perceived pain intensity, negative mood, fatigue, sleep quality, perceived cognitive difficulties, and quality of life in comparison with patients with non-NP SLE as well as with healthy controls. / published_or_final_version / Clinical Psychology / Master / Master of Social Sciences

Systemic lupus erythematosus (SLE) is a chronic multi-organ autoimmune disease that is characterised by diverse clinical manifestations. Immunologically, SLE features a prominent “interferon (IFN) signature” which is marked by an elevated expression of type I IFN-regulated genes in blood and tissue cells of patients with this condition. Plasmacytoid dendritic cells (pDCs), also known as the most potent type I IFN-producing cells, are therefore considered the major culprit in SLE pathogenesis. Previous studies from our group have demonstrated abnormalities in circulating and bone marrow (BM)-derived pDCs from SLE patients. In the light of this, the present study was undertaken to further evaluate the role of pDCs in SLE development and to seek for key mediator(s) that might lead to functional aberrations of pDCs in this condition. Recently, a growing attention has been drawn to microRNAs (miRNAs) for their critical role in regulating immune cell function and strong association with autoimmune diseases. Therefore, the current study hypothesised that microRNAs played an important role in modulating pDC response(s) to toll-like receptor (TLR) stimulation, and that dysregulated microRNA expression induction was responsible for pDC abnormalities in SLE pathogenesis. The spontaneous lupus mouse model, F1 hybrid of New Zealand Black and White strains (NZB/W F1), was used in this study. The disease profile of NZB/W F1 was characterised based on the development of serum antinuclear antibodies and proteinuria. Specifically, the development of lupus in these mice (symptomatic mice) was illustrated by high titres of serum antinuclear antibodies, persistent proteinuria, glomerular immune complex deposition and elevated expression of pro-inflammatory cytokine genes in the kidney. Young NZB/W F1 (pre-symptomatic) as well as age- and sex-matched non-lupus maternal NZW mice were used as controls. While the development of pDCs appeared to be unaffected by lupus, elevated upregulation of MHC class II and co-stimulatory molecules, and induction of IFN-stimulated gene Ifitm3 in TLR7-stimulated lupus pDCs suggested phenotypic and functional hypersensitivity of these cells. Furthermore, analysis of the expression profile of miRNAs in pDCs upon TLR7 activation identified six differentially regulated targets. Among these, miR-155 was the most highly induced and its induction was consistently higher in pDCs from symptomatic NZB/W F1 mice. Nevertheless, transfection of miR-155 mimics into pre-symptomatic pDCs resulted in a reduced expression of Ifitm3, suggesting that miR-155 has a negative regulatory role in IFN production in pDCs. The finding of upregulated induction of miR-155 in lupus pDCs reported in this thesis is in line with previous studies, which showed increased expression of miR-155 in splenic lymphocytes of lupus NZB/W F1 mice. Results obtained from the transfection experiments are also in accordance with other previous studies, which showed miR-155 functioned as a negative feedback regulator of IFN production in pDCs. However, the mechanism of the association between miR-155 expression and increased IFN response in SLE requires further investigations. It is hoped that findings from this study contribute to a better understanding of SLE pathogenesis and ignite future interests in evaluating the molecular layer of regulation in autoimmunity. / published_or_final_version / Medicine / Doctoral / Doctor of Philosophy

Lupus nephritis is characterized by the production of anti-dsDNA antibodies, deposition of immune complexes within the kidney parenchyma, proliferation of resident renal cells and induction of inflammatory and fibrotic processes. Approximately 70% of patients with lupus nephritis show immune aggregates along the tubular basement membrane, which is accompanied by an influx of infiltrating cells and increased intra-renal expression of IL-6. Much attention has focused on the inflammatory processes in the kidney during pathogenesis of lupus nephritis whereas mechanisms of fibrogenesis are less well characterized. Tubulo-interstitial injury is a key indicator of poor prognosis of renal function. Given that the tubulo-interstitium occupies over 80% of the kidney volume, injury to this compartment will have a major impact on renal function. There is evidence to show that proximal tubular epithelial cells (PTEC) undergo epithelial-to-mesenchymal transition (EMT) during pathological disorders and adopt a fibroblastic morphology with increased fibrogenic potential. We have previously demonstrated that anti-dsDNA antibodies bound directly to the surface of PTEC through cross-reactive proteins, which were subsequently internalized and translocated to the nucleus where they induced functional changes. Using a proteomic approach, this study identified the cross-reactive antigens that mediated anti-dsDNA antibody binding and intracellular localization in PTEC and the functional consequences thereafter, focusing on EMT and fibrogenic events. Human polyclonal anti-dsDNA antibodies isolated from patients with lupus nephritis bound to Ku70 in plasma membrane extracts isolated from PTEC, and to Ku70, Ku80 and major vault protein in cytosolic and nuclear fractions. Anti-dsDNA antibodies increased synthesis of Ku70, Ku80 and major vault protein in PTEC in a time-dependent manner. Expression of these proteins was localized to proximal tubules especially those undergoing atrophy, and staining was more prominent in renal biopsies from patients with lupus nephritis compared to non-lupus renal disease or control specimens. Binding of anti-dsDNA antibodies to PTEC increased phosphorylation of MAPK and PKC signaling pathways that was accompanied by a concomitant increase in IL-6, IL-8 and TGF-1 secretion and synthesis of β-catenin, fibroblast specific protein-1, fibronectin and laminin. Inhibition of MAPK and PKC signaling pathways with specific inhibitors revealed differential regulation of inflammatory and fibrotic processes by these signaling pathways. In this respect, increased ERK, p38 MAPK, JNK and PKC phosphorylation in PTEC following anti-dsDNA antibody stimulation enhanced IL-6, IL-8 and fibronectin synthesis, whereas increased ERK and JNK phosphorylation upregulated TGF-β1 secretion. Increased β-catenin synthesis was mediated through JNK and PKC phosphorylation. Taken together, our data suggest that PTEC contribute to the pathogenesis of renal inflammation and fibrosis in lupus nephritis. We hypothesize that anti-dsDNA antibodies bind to Ku70 on the plasma membrane of PTEC to mediate inflammation, cell activation and increased fibrogenesis. Although synthesis of EMT markers was increased in PTEC after anti-dsDNA antibody stimulation, transition to a fibroblastic morphology was not observed under our experimental setting suggesting that induction of the EMT cascade is an early event before phenotypic alterations. / published_or_final_version / Medicine / Master / Master of Philosophy