血管紧张素II(Ang II)在慢性肾脏病中起重要的致病作用，尽管体外研究证实TGF-β/Smad3起正调控，Smad7起负调控作用，但Smad3在Ang II 诱导的肾脏损害中的作用仍不清楚。因此，本论文在Smad3基因敲除的小鼠中通过Ang II诱导的高血压肾损伤模型研究TGF-β/Smad3通路的作用及机制。如第三章所述，敲除Smad3的小鼠不发生Ang II诱导的高血压肾损伤如尿白蛋白，血肌酐升高，肾脏炎症（如IL-1, TNFα上调，F4/80+ 巨噬细胞浸润）及肾脏纤维化（包括α-SMA+肌成纤维细胞聚集，和胶原基质沉积）。敲除Smad3对高血压肾病起保护作用是因为抑制了肾脏TGF-β1表达及Smurf2 依赖的Smad7泛素化降解，从而抑制TGF-β/Smad3介导的肾脏纤维化和NF-B介导的炎症。 / 越来越多的证据显示Ang II产生和降解的平衡在高血压肾病的发展中起重要作用。在这篇论文中，我们假设ACE2的降解可能会引起Ang II代谢通路的失衡，从而加重其介导的高血压肾病。这一假设在第四章得到验证，在单侧输尿管梗阻小鼠模型敲除ACE2加重肾内Ang II介导的肾脏纤维化和炎症。这一变化与肾内高水平的Ang II和降低的血管紧张素1-7，上调的血管紧张素受体1，及激活的TGF-β/Smad3 和 NF-κB 信号通路有关。另外，升高的Smurf2介导的Smad7泛素化降解加重了敲除ACE2 基因后Ang II介导的肾脏纤维化和炎症。 / 因为Smad7 是TGF-β/Smad和NF-κB通路的负调控因子，因此论文进一步提出假设过表达Smad7能够阻止Ang II介导的肾脏纤维化炎症。如第五章所述，ACE2基因敲除的小鼠肾内升高的Smurf2介导了肾脏Smad7 的泛素化降解， 加重了Ang II 介导的肾脏损伤如白蛋白尿，血肌酐的升高，及肾脏纤维化和炎症，这与激活的Ang II/TGF-β/Smad3/NF-κB信号有关。相反，过表达Smad7能够阻断TGF-β/Smad3 介导的肾脏纤维化和 NF-κB介导的肾脏炎症以缓解ACE2敲除小鼠中Ang II诱导的肾脏损伤。 / 总之，Smad3在Ang II诱导的高血压肾脏病中起关键作用，Smad7具有肾脏保护作用。 ACE2敲除引起Ang II产生和降解的失衡从而增加肾内Ang II的产生，加重TGF-β/Smad3介导的肾脏纤维化和NF-κB介导的肾脏炎症，而这可以被Smad7缓解。 本论文得出结论针对TGF-β/Smad3 和NF-κB通路，通过过表达Smad7可能为高血压肾脏病和慢性肾脏病提供新的治疗策略。 / Angiotensin II (Ang II) plays a pathogenic role in chronic kidney disease (CKD). Although in vitro studies find that Ang II mediates renal fibrosis via the Smad3-dependent mechanism, the functional role of Smad3 in Ang II-mediated kidney disease remains unclear. Therefore, this thesis examined the pathogenesis role and mechanisms of TGF-β/Smad3 in Ang II-mediated hypertensive nephropathy in Smad3 Knockout (KO) mice. As described in Chapter III, Smad3 deficiency protected against Ang II-induced hypertensive nephropathy as demonstrated by lowering levels of albuminuria, serum creatinine, renal inflammation such as up-regulation of pro-inflammatory cytokines (IL-1β, TNFα) and infiltration of CD3+ T cells and F4/80+ macrophages, and renal fibrosis including α-SMA+ myofibroblast accumulation and collagen matrix deposition (all p<0.01). Inhibition of hypertensive nephropathy in Smad3 KO mice was associated with reduction of renal TGF-β1 expression and Smurf2-associated ubiquitin degradation of renal Smad7, thereby blocking TGF-β/Smad3-mediated renal fibrosis and NF-κB-driven renal inflammation. / Increasing evidence shows that the balance between the generation and degradation of Ang II is also important in the development of hypertensive nephropathy. In this thesis, we also tested a hypothesis that enhanced degradation of ACE2 may result in the imbalance between the Ang II generation and degradation pathways, therefore enhancing Ang II-mediated hypertensive nephropathy and CKD. This hypothesis was examined in a mouse model of unilateral ureteral obstructive nephropathy (UUO) induced in ACE2 KO mice. As described in Chapter IV, loss of ACE2 increased intrarenal Ang II-mediated renal fibrosis and inflammation in the UUO kidney. These changes were associated with higher levels of intrarenal Ang II, reduced Ang 1-7, up-regulated AT1R, and activation of TGF-β/Smad3 and NF-κB signalling. In addition, enhanced Smurf2-associated ubiquitin degradation of Smad7 was another mechanism by which loss of ACE2 promoted Ang II-mediated renal fibrosis and inflammation. / Because Smad7 is a negative regulator for TGF-β/Smad and NF-κB signalling, this thesis also examined a hypothesis that overexpression of renal Smad7 may be able to prevent Ang II-induced, TGF-β/Smad3-mediated renal fibrosis and NF-κB-driven renal inflammation in ACE2 KO mice. As described in Chapter V, mice null for ACE2 resulted in degradation of renal Smad7 via the Smurf2 -- dependent mechanism (all p<0.01). Enhanced Ang II-mediated renal injury in ACE2 KO mice such as albuminuria, serum creatinine, and renal fibrosis and inflammation was associated with enhanced activation of Ang II/TGF-β/Smad3/NF-κB signalling. In contrast, overexpression of Smad7 was able to rescue AngII-induced progressive renal injury in ACE2 KO mice by blocking TGF-β/Smad3 and NF-κB-dependent renal fibrosis and inflammation. In conclusion, Smad3 plays an essential role in Ang II-induced hypertensive nephropathy, while Smad7 is reno-protective. Loss of ACE2 results in the imbalance between the Ang II generation and degradation pathways and thus enhances intrarenal Ang II-induced, TGF-β/Smad3-mediated renal fibrosis and NF-κB-driven renal inflammation, which can be rescued by Smad7. Results from this thesis indicate that targeting TGF-β/Smad3 and NF-κB pathways by overexpressing Smad7 may represent a novel therapy for hypertensive nephropathy and CKD. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Liu, Zhen. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 189-209). / Abstracts also in Chinese. / ABSTRACT --- p.i / DECLARATION --- p.v / ACKNOWLEDGEMENTS --- p.vi / LIST OF PUBLICATION --- p.viii / TABLE OF CONTENTS --- p.ix / LIST OF ABBREVIATIONS --- p.xiv / LIST OF FIGURES AND TABLES --- p.xvii / CHAPTER I --- p.1 / INTRODUCTION --- p.1 / Chapter 1.1 --- RAS (Renin-Angiotensin system) --- p.2 / Chapter 1.1.1 --- Circulating RAS --- p.2 / Chapter 1.1.2 --- Tissue RAS --- p.5 / Chapter 1.1.2.1 --- Angiotensinogen --- p.6 / Chapter 1.1.2.2 --- Renin Receptors --- p.7 / Chapter 1.1.2.3 --- ACE and ACE2 --- p.9 / Chapter 1.1.2.4 --- Angiontensin II and Its Receptors --- p.10 / Chapter 1.1.2.5 --- AT2 Receptors --- p.11 / Chapter 1.1.2.6 --- Chymase-Alternative Pathways of Ang II Generation --- p.13 / Chapter 1.1.2.7 --- Ang (1-7) Receptor (MAS) --- p.13 / Chapter 1.2 --- Ang II and Renal Injury --- p.15 / Chapter 1.2.1 --- Pressure Dependent Renal Injury Induced by Ang II --- p.15 / Chapter 1.2.2 --- Ang II induces production of cytokines and growth factors --- p.16 / Chapter 1.2.3 --- Ang II and Renal Fibrosis --- p.17 / Chapter 1.2.4 --- Signalling Mechanisms Involved in Ang II-Induced Renal Fibrosis --- p.18 / Chapter 1.2.5 --- Ang II in Renal Inflammation --- p.22 / Chapter 1.3 --- TGF-β/Smad Signalling Pathway in Renal Disease --- p.24 / Chapter 1.3.1 --- Mechanisms of TGF-β/Smad Activation --- p.24 / Chapter 1.3.1.1 --- Cross-talk Between Smads and Other Signalling Pathways in Renal Fibrosis --- p.26 / Chapter 1.3.1.2 --- Activation of R-Smads (Smad2 and Smad3) --- p.28 / Chapter 1.3.2 --- Inhibitory Role of Smad7 in Renal Fibrosis and Inflammation --- p.30 / Chapter CHAPTER II --- p.32 / MATERIALS AND METHODS --- p.32 / Chapter 2.1 --- MATERIALS --- p.33 / Chapter 2.1.1 --- Regents and Equipments --- p.33 / Chapter 2.1.1.1 --- Regents and Equipments for Cell Culture --- p.33 / Chapter 2.1.1.2 --- General Reagents and Equipments for Real-time PCR --- p.34 / Chapter 2.1.1.3 --- General Reagents and Equipments for Masson Trichrome Staining --- p.34 / Chapter 2.1.1.4 --- General Reagents and Equipments for Immunohistochemistry --- p.35 / Chapter 2.1.1.5 --- General Reagents and Equipments for Western Blot --- p.35 / Chapter 2.1.1.6 --- General Reagents and Equipments for ELISA --- p.37 / Chapter 2.1.1.7 --- Measurement of Blood Pressure in Mice --- p.37 / Chapter 2.1.1.8 --- Reagents and Equipment for Genotyping --- p.37 / Chapter 2.1.2 --- Buffers --- p.38 / Chapter 2.1.2.1 --- Immunohistochemistry Buffers --- p.38 / Chapter 2.1.2.2 --- Buffers for Western Blotting --- p.40 / Chapter 2.1.2.3 --- ELISA Buffers --- p.44 / Chapter 2.1.2.4 --- Primer Sequences --- p.46 / Chapter 2.1.2.5 --- Primary Antibodies --- p.47 / Chapter 2.1.2.6 --- Secondary Antibodies --- p.48 / Chapter 2.2 --- METHODS --- p.49 / Chapter 2.2.1 --- Animal --- p.49 / Chapter 2.2.1.1 --- Genotypes of Gene KO Mice --- p.49 / Chapter 2.2.1.2 --- Animal Model of Unilateral Ureteral Obstruction (UUO) --- p.50 / Chapter 2.2.1.3 --- Animal Model of Angiotensin II (Ang II)-Induced Hypertensive Nephropathy --- p.50 / Chapter 2.2.1.4 --- Measurement of Ang II and Ang 1-7 --- p.51 / Chapter 2.2.2 --- Cell Culture --- p.51 / Chapter 2.2.3 --- Microalbuminuria and Renal Function --- p.51 / Chapter 2.2.3.1 --- Urine Collection --- p.51 / Chapter 2.2.3.2 --- Plasma Collection --- p.52 / Chapter 2.2.3.3 --- Microalbuminuria --- p.52 / Chapter 2.2.3.4 --- Creatinine Measurement --- p.52 / Chapter 2.2.4 --- Real-time PCR --- p.53 / Chapter 2.2.4.1 --- Total RNA Extraction --- p.53 / Chapter 2.2.4.2 --- Reverse Transcription --- p.53 / Chapter 2.2.4.3 --- Real-time PCR --- p.54 / Chapter 2.2.4.4 --- Analysis of Real-time PCR --- p.54 / Chapter 2.2.5 --- Western Blot --- p.55 / Chapter 2.2.5.1 --- Protein Preparation --- p.55 / Chapter 2.2.5.2 --- Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE) --- p.56 / Chapter 2.2.5.3 --- Protein Transfer (Wet Transfer) --- p.56 / Chapter 2.2.5.4 --- Incubation of Antibodies --- p.56 / Chapter 2.2.5.5 --- Scanning and Analysis --- p.57 / Chapter 2.2.5.6 --- Stripping --- p.57 / Chapter 2.2.6 --- Histochemistry --- p.57 / Chapter 2.2.6.1 --- Tissue Fixation --- p.57 / Chapter 2.2.6.2 --- Tissue Embedding and Sectioning --- p.58 / Chapter 2.2.6.3 --- Preparation of Paraffin Tissue Sections for PAS Staining --- p.58 / Chapter 2.2.6.4 --- PAS Staining --- p.58 / Chapter 2.2.7 --- Immunohistochemistry --- p.59 / Chapter 2.2.7.1 --- Tissue Embedding and Sectioning --- p.59 / Chapter 2.2.7.2 --- Antigen-Antibody Reaction and Immunostaining --- p.59 / Chapter 2.2.7.3 --- Semi-quantification of Immunohistochemistry --- p.60 / Chapter 2.2.8 --- Statistical Analysis --- p.60 / Chapter CHAPTER III --- p.62 / ROLE OF SMAD3 IN ANGIOTENSIN II-INDUCED RENAL FIBROSIS AND INFLAMMATION --- p.62 / Chapter 3.1 --- INTRODUCTION --- p.63 / Chapter 3.2 --- MATERIALS AND METHODS --- p.64 / Chapter 3.2.1 --- Generation of Smad3 KO Mice --- p.64 / Chapter 3.2.2 --- Mouse Model of Ang II-Induced Hypertension --- p.64 / Chapter 3.2.3 --- Histology and Immunohistochemistry --- p.65 / Chapter 3.2.4 --- Renal Function and Proteinuria --- p.65 / Chapter 3.2.5 --- Western Blot Analysis --- p.65 / Chapter 3.2.6 --- Real-time RT-PCR --- p.65 / Chapter 3.2.7 --- In Vitro Study of Mesangial Cells from Smad3 WT and KO Mice --- p.66 / Chapter 3.2.8 --- Statistical Analysis --- p.66 / Chapter 3.3 --- RESULTS --- p.66 / Chapter 3.3.1 --- Smad3 KO Mice Prevents Ang II-induced Renal Injury Independent of Blood Pressure --- p.66 / Chapter 3.3.2 --- Smad3 KO Mice Are Resistant to Renal Fibrosis in a Mouse Model of Ang II -Induced Hypertension --- p.70 / Chapter 3.3.3 --- Smad3 KO Mice Are Resistant to Renal Inflammation in a Mouse Model of Ang II-Induced Hypertension --- p.76 / Chapter 3.3.4 --- Smad3 Deficiency Inhibits Ang II-induced Renal Fibrosis and Inflammation In Vitro --- p.82 / Chapter 3.3.5 --- Smad3 Mediates Ang II-Induced Renal Fibrosis by the Positive Feedback Mechanism of TGF-β/Smad Signalling --- p.87 / Chapter 3.3.6 --- Enhancing NF-κB Signalling via the Smurf2-associated Ubiquitin Degradation of Smad7 In Vivo and In Vitro --- p.92 / Chapter 3.4 --- DISCUSSION --- p.101 / Chapter 3.5 --- CONCLUSION --- p.106 / Chapter CHAPTER IV --- p.107 / LOSS OF ANGIOTENSIN-CONVERTING ENZYME 2 ENHANCES TGF-β/SMAD-MEDIATED RENAL FIBROSIS AND NF-κB-DRIVEN RENAL INFLAMMATION IN A MOUSE MODEL OF OBSTRUCTIVE NEPHROPATHY --- p.107 / Chapter 4.1 --- INTRODUCTION --- p.108 / Chapter 4.2 --- MATERIALS AND METHODS --- p.109 / Chapter 4.2.1 --- Generation of ACE2 KO Mice --- p.109 / Chapter 4.2.2 --- Mouse Model of Unilateral Ureteral Obstruction (UUO) --- p.109 / Chapter 4.2.3 --- Histology and Immunohistochemistry --- p.110 / Chapter 4.2.4 --- Western Blot Analysis --- p.110 / Chapter 4.2.5 --- Real-time RT-PCR --- p.110 / Chapter 4.2.6 --- Measurement of Ang II and Ang 1-7 --- p.110 / Chapter 4.2.7 --- Statistical Analysis --- p.111 / Chapter 4.3 --- RESULTS --- p.111 / Chapter 4.3.1 --- ACE2 KO Mice Accelerate Renal Fibrosis and Inflammation Independent of Blood Pressure in the UUO Nephropathy --- p.111 / Chapter 4.3.2 --- Loss of ACE2 Enhances Ang II, Activation of TGF-β/Smad and NF-κB Signalling Pathways --- p.128 / Chapter 4.3.3 --- Loss of Renal Smad7 Is an Underlying Mechanism Accounted for the Progression of TGF-β/Smad-mediated Renal Fibrosis and NF-κB-Driven Renal Inflammation in the UUO Nephropathy in ACE2 KO Mice --- p.140 / Chapter 4.4 --- DISCUSSION --- p.143 / Chapter 4.5 --- CONCLUSION --- p.147 / CHAPTER V --- p.148 / PROTECTIVE ROLE OF SMAD7 IN HYPERTENSIVE NEPHROPATHY IN ACE2 DEFICIENT MICE --- p.148 / Chapter 5.1 --- INTRODUCTION --- p.149 / Chapter 5.2 --- MATERIALS AND METHODS --- p.151 / Chapter 5.2.1 --- Generation of ACE2 KO Mice --- p.151 / Chapter 5.2.2 --- Mouse Model of Ang II-Induced Hypertension --- p.151 / Chapter 5.2.3 --- Smad7 Gene Therapy --- p.151 / Chapter 5.2.4 --- Histology and Immunohistochemistry --- p.152 / Chapter 5.2.5 --- Western Blot Analysis --- p.153 / Chapter 5.2.6 --- Real-time RT-PCR --- p.153 / Chapter 5.2.7 --- Measurement of Ang II and Ang 1-7 --- p.153 / Chapter 5.2.8 --- Statistical Analysis --- p.153 / Chapter 5.3 --- RESULTS --- p.154 / Chapter 5.3.1 --- Deletion of ACE2 Accelerates Ang II-Induced Renal Injury --- p.154 / Chapter 5.3.2 --- Renal Fibrosis and Inflammation are Enhanced in ACE2 KO Mice with Ang II-Induced Renal Injury --- p.156 / Chapter 5.3.3 --- Enhanced Activation of TGF-β/Smad3 and NF-κB Signalling Pathways are Key Mechanism by Which Deletion of ACE2 Promotes Ang II-Induced Renal Injury --- p.163 / Chapter 5.3.4 --- Loss of Renal Smad7 Mediated by Smurf2-ubiquintin Degradation Pathway Contributes to Ang II-Induced Hypertensive Nephropathy in ACE2 KO Mice --- p.166 / Chapter 5.3.5 --- Overexpression of Smad7 is able to Rescue Ang II-induced Renal Injury in ACE2 KO Mice by Blocking Both TGF-β/Smad3 and NF-κB-dependent Renal Fibrosis and Inflammation --- p.168 / Chapter 5.4 --- DISCUSSION --- p.180 / Chapter 5.5 --- CONCLUSION --- p.182 / Chapter CHAPTER VI --- p.183 / SUMMARY AND DISCUSSION --- p.183 / Chapter 6.1 --- Smad3 Plays a Key Role in Ang II-Induced Hypertensive Nephropathy --- p.185 / Chapter 6.2 --- The Intrarenal Ang II Plays a Key Role in the Progress of Ang II-Mediated Renal Injury --- p.185 / Chapter 6.3 --- A Novel Finding of Ang II-Smad3-TGF-β-Smad3 amplification loop in Ang II-mediated Renal Fibrosis --- p.186 / Chapter 6.4 --- Smurf2-associated Ubiquitin-Proteasome Degradation of Smad7 Contributes to the Progression of Ang II-mediated Renal Injury in ACE2 KO Mice --- p.187 / Chapter 6.5 --- Smad7 Protects against Ang II-Mediated Hypertensive Kidney Disease by Negatively Regulating TGF-β/Samd and NF-κB Signalling --- p.187 / REFERENCE --- p.189

Sub-Saharan Africa bears 70% of the global HIV burden with KwaZulu-Natal (KZN) identified as the epicenter of this pandemic. HIV related nephropathy (HIVRN) exceeds any other causes of kidney diseases responsible for end stage renal disease, and has been increasingly recognized as a significant cause of morbidity and mortality. There is nonetheless a general lack of surveillance and reporting for HIVRN exists in this geographical region. Consequentially, the aim of this study was to outline the histopathogical spectrum of HIVRN within KZN. Moreover, from a pathology standpoint, it is important to address whether HIVRN was a direct consequence of viral infection of the renal parenchyma or is it a secondary consequence of systemic infection. Additionally, an evaluation of the efficacy of Highly Active Anti-Retroviral Therapy (HAART) in combination with angiotensin converting enzyme inhibitors (ACE-I) was performed via a genetic appraisal of localized replication of HIV-1 in the kidney, ultrastructural review and immunocytochemical expression of a podocyte maturity and proliferation marker pre and post-HAART. Blood and renal biopsies were obtained from 30 children with HIV related nephropathy pre- HAART, followed-up clinically for a period of 1 year. This cohort formed the post-HAART group. Clinical and demographic data were collated and histopathology, RT-PCR, sequencing, immunocytochemistry and transmission electron microscopy was performed. The commonest histopathological form of HIVRN in children (n = 30) in KZN was classical focal segmental glomerular sclerosis (FSGS) presented in 13(43.33%); mesangial hypercellularity 10(30%); mesangial, HIV associated nephropathy 3(11%) and minimal change disease 2(6.67%). Post-HAART (n = 9) the predominant pathology was mesangial hypercellularity 5(55.56%); FSGS 3(33.33%) and sclerosing glomerulopathy 1(11.11%). This study also provides data on the efficacy of HAART combined with ACE-I. The immunostaining pattern of synaptopodin, Ki67 and p24 within the glomerulus expressed as a mean field area percentage was significantly downregulated in the pre-HAART compared to the post-HAART group respectively (1.14 vs. 4.47%, p = 0.0068; 1.01 vs.4.68, p < 0.001; 4.5% vs 1.4%, p = 0.0035). The ultrastructural assessment of all biopsies conformed to their pathological appraisal however, features consistent with viral insult were observed. Latent HIV reservoirs were observed within the podocyte cytoplasm but was absent in mesangial or endothelial cells. Real-Time polymerase chain reaction assays provided evidence of HIV-1 within the kidney. Sequence analysis of the C2-C5 region of HIV-1 env revealed viral diversity between renal tissue to blood. In contrast to a collapsing type of FSGS that occurs in adults, the spectrum of paediatric nephropathy in treatment-naive children within KwaZulu-Natal was FSGS with mesangial hypercellularity. Additionally, our study demonstrates podocyte phenotype dysregulation pre- HAART and reconstitution post therapy. Evidence of ultrastructural viral reservoirs within epithelial cells is supported by a genetic appraisal confirming the ubiquitous presence of HIV DNA in renal tissue. Moreover, sequence analysis showed viral evolution and compartmentalization between renal viral reservoirs to blood. Finally, the interplay of viral genes and host response, influenced by genetic background, may contribute to the variable manifestations of HIV-1 infection in the kidney in our paediatric population. / Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2012.