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

Background: Repeat renal biopsies in patients with lupus nephritis (LN) are usually done to guide treatment or to establish disease chronicity. Their value is not clear from available literature. There is also no available data in Africa to guide clinicians. Methods: This was a retrospective study of patients undergoing a repeat renal biopsy between January 2003 and December 2014 from a single centre in Cape Town, South Africa. Relevant demographic, clinical and histological records of patients with repeat renal biopsies were documented. Comparison of data from 1st and 2nd renal biopsy was performed. Results: 44 patients had at least 2 biopsies done during the study period. Most patients were females (81.8%). The mean biopsy interval was 2.8± 1.8 (range 0.38 – 9.4) years. Proteinuria was the main indication for the repeat biopsy (36.1%). The glomerular filtration rate and proteinuria worsened between the two biopsies (p=0.001 and 0.019) respectively suggesting disease progression. Most patients (65.4%) with a non-proliferative class of LN at first biopsy progressed into a proliferative class whereas patients with initial proliferative LN at first biopsy (77.8%) remained as proliferative at repeat biopsy. Treatment was changed in 85% of patients at second biopsy. Conclusion: Repeat renal biopsies in patients with LN presents a useful means of assessing disease progression and provides guidance regarding modification of treatment. More studies are however required to evaluate the value of repeat biopsies and perhaps the need for protocol renal biopsies in patients with LN.

No description available.

No description available.

A farmacocinética dos enantiômeros da ciclofosfamida (CPA) foi avaliada em pacientes portadores de nefrite lúpica distribuídos em dois grupos de acordo com o clearance da creatinina: Grupo 1 90,6-144,6mL/min/1,73m2 e Grupo 2 42,8-76,4mL/min/1,73m2. Os pacientes foram tratados com doses de 0,75 a 1,3g de ciclofosfamida racêmica sob forma de infusão com duração de 2h e com 1mg de midazolam (MDZ) administrado via endovenosa para a avaliação da atividade in vivo do CYP3A. As concentrações plasmáticas dos enantiômeros da CPA e do MDZ foram avaliadas por LC-MS/MS. Os enantiômeros da CPA foram resolvidos na coluna Chiralcel OD-R, com fase móvel constituída por mistura de acetonitrila e água (75:25, v/v) adicionada de 0,2% de ácido fórmico. Os enantiômeros da CPA foram extraídos do plasma com recuperações maiores que 95% e o limite de quantificação obtido foi de 2,5ng de cada enantiômero da CPA/mL plasma. As seguintes diferenças (teste de Wilcoxon, p<0,05) foram observadas nos parâmetros farmacocinéticos entre os enantiômeros (S)-(-)-CPA e (R)-(+)-CPA para os pacientes do Grupo 1: AUC do tempo 0 ao infinito 152,41 vs 129,25g.h/mL; Cl 3,28 vs 3,89L/h; Vd 31,38 vs 29,74L e t1/2 6,79 vs 5,56h e para os pacientes do Grupo 2: AUC do tempo 0 ao infinito 167,20 vs 139,08g.h/mL; Cl 2,99 vs 3,59L/h e t1/2 6,15 vs 4,99h. Não foi observada diferença (teste de Mann-Whitney, p<0,05) nos parâmetros farmacocinéticos de ambos os enantiômeros entre os grupos 1 e 2. Não foi observada corrrelação entre o clearance do MDZ (2,92-16,40ml/min.kg) e o clearance de cada enantiômero da CPA. Concluindo, a farmacocinética da CPA é enantiosseletiva em pacientes portadores de nefrite lúpica com acúmulo plasmático do enantiômero (S)-(-)-CPA e a farmacocinética de ambos os enantiômeros da CPA não é alterada pela agravamento da função renal. / The pharmacokinetics of cyclophosphamide (CYC) enantiomers was evaluated in patients with lupus nephritis distributed in two groups according to creatinine clearance; Group 1 - 90.6-144.6mL/min/1.73m2 and Group 2 - 42.8- 76.4mL/min/1.73m2. All patients were treated with 0.75 to 1.3g of racemic CYC as a 2-hour infusion and with 1mg intravenous midazolam as a drug marker. CYC enantiomers and midazolam concentrations in plasma were measured by LC-MS/MS. CYC enantiomers were separated on a Chiralcel OD-R column, with the mobile phase consisting of a mixture of acetonitrile and water (75:25, v/v) plus 0.2% formic acid. Recovery rates were higher than 95% and the quantification limit was 2.5ng/ml plasma for both enantiomers. The coefficients of variation and the relative errors obtained for the validation of intra- and interassay precision and accuracy were less than 10%. The following differences in the pharmacokinetic parameters (Wilcoxon test, p<0.05) were observed between the (S)-(-) and (R)-(+) enantiomers for Group 1 AUC from time 0 to infinity 152.41 vs 129.25g.h/mL, Cl 3.28 vs 3.89L/h, Vd 31.38 vs 29.74L and t1/2 6.79 vs 5.56h and for Group 2 AUC from time 0 to infinity 167.20 vs 139.08g.h/mL, Cl 2.99 vs 3.59 L/h and t1/2 6.15 vs 4.99 h. No differences (Mann-Whitney test, p<0.05) were observed between Groups 1 and 2 in the pharmacokinetics parameters of both enantiomers. No significant relationship was observed between midazolam clearance (2.92-16.40 ml/min.kg) and clearance of each CYC enantiomer. In conclusion, CYC kinetic disposition is enantioselective resulting in higher exposure of (S)-(-)-CYC in lupus nephritis patients and the pharmacokinetic parameters of both enantiomers are not altered by the worsening of renal condition.

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 188-245). Also available online.

Thesis (Ph. D.)--University of Hong Kong, 2009. / Includes bibliographical references (leaves 188-245). Also available in print.

published_or_final_version / Medicine / Doctoral / Doctor of Philosophy

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

Access to abstract permanently restricted to Ball State community only. / Access to thesis permanently restricted to Ball State community only. / Department of Physiology and Health Science