In der vorliegenden Untersuchung wurde der Einfluss des AT1-R -Antagonisten Valsartan auf die Nierenfunktion bei nierentransplantierten Ratten mit der Fragestellung analysiert, ob eine Langzeittherapie mit diesem Wirkstoff einen positiven Effekt auf die Nierenfunktion entfaltet und sich somit sein Einsatz gegen die Entwicklung einer chronischen Transplantatnephropathie empfiehlt. Die über den gesamten Versuchszeitraum gegenüber der allogenen Kontrollgruppe signifikant erhöhten Urinvolumina stellen allein kein Indiz für eine bessere Nierenfunktion unter Therapie mit Valsartan dar. Dieses Ergebnis ist am ehesten durch Veränderungen der glomerulären Hämodynamik post transplantationem zu erklären. Wie nunmehr in mehreren tierexperimentellen Untersuchungen und klinischen Patientenstudien nachgewiesen worden ist, zeigt sich auch in der Synopsis der eigenen Befunde ein signifikant günstigerer Verlauf des Serumkreatinins, des Serum-BUN, der Kreatinin-Clearance sowie der Proteinurie unter Blutdrucksenkung mit dem AT1-R-Antagonisten Valsartan. An einigen Zeitpunkten der Studie waren die Ergebnisse allerdings statistisch nicht signifikant. Eine positive Wirkung auf die Transplantatfunktion und auf das Langzeitüberleben der Versuchstiere ist anzunehmen, ist aber in dieser Studie nicht weiter verfolgt worden. Eine Untersuchung mit einer größeren Anzahl von Versuchstieren und über einem längeren Versuchzeitraum hin scheint sinnvoll, um signifikante Unterschiede zwischen den Kontrollgruppen und der Versuchgruppe unter Valsartan zu belegen. Die im Vergleich zu den Kontrollgruppen geringere Entwicklung des Körpergewichts hatte bei der o.g. Fragestellung keine Relevanz. Wie in zahlreichen klinischen Studien für die Progredienz des chronischen Nierenversagens seit längerem eindrucksvoll belegt ist, scheint eine pharmakologische Blockade des RAAS auch einen protektiven Effekt auf die Entstehung einer chronischen Transplantatnephropathie zu entfalten. Die eigene Untersuchung liefert hinreichend Belege für diese Vermutung. Auch wenn in einzelnen Studien über negative Auswirkungen einer Blockade des RAAS auf die Transplantatfunktion berichtet worden ist, gibt es genügend Anhaltspunkte für einen günstigeren Verlauf nach Transplantation sowohl in Tierversuchen als auch für den transplantierten Patienten. Das allmähliche Fortschreiten der chronischen Transplantatnephropathie kann damit allerdings nicht ganz aufgehalten werden. Somit bleibt trotz dieser erfolgversprechenden experimentellen Ergebnisse nach Organtransplantation durch diese neuen Therapieansätze (Immunsuppressiva, RAAS-Blockade, Plasmapherese u.a.) die chronische Transplantat-Abstoßung immer noch ein therapeutisch fortbestehendes Problem. Weitere Untersuchungen über die Zusammenhänge immunologischer sowie nicht-immunologischer Ursachen einer chronischen Transplantatnephropathie und eine Optimierung der Immunsuppression sind deshalb auch weiterhin dringend erforderlich. / In spite of the new immunosuppressive drug therapies used in renal transplants, chronic rejection continues to be a major cause of graft dysfunction after the first posttransplant year. This so called chronic allograft nephropathy is characterized by a slow but variable decrease in renal function appearing months or years after transplantation, is often accompanied or proceded by proteinuria ans hypertension and does not respond to immunosuppressive therapy. In our study we could show that posttransplant therapy with the angiotensin-II-receptor antagonist Valsartan improves chronic renal allograft nephropathy in Lewis rats. A similar effect on long-term survival of human kidney transplants can be supposed. Nevertheless further investigations have to be done in oder to understand all immunologigal and non immunological mechanisms of renal chronic rejection and to improve therapies.

Conclusion. These data provide a clue that AT1 receptor blocker could effectively attenuate severe form of pancreatitis and its-associated systemic inflammation in experimental models of AP. The underlying mechanisms may be involved in Ang II-induced NADPH oxidase derived oxidative stress, particularly NFkappaB and ERK1/2-dependent CREB activation. The pro-inflammatory pathways would commonly converge to transcribe an array of genes such as IL-6, thus regulating the severity of pancreatitis and the onset of its complications. All these in vivo and in vitro data provide substantial evidence that Ang II is involved in AT1 receptor-mediated signaling cascade in regulating the pathogenesis of AP. The findings provide a new insight on potential application of AT 1 receptor blockade for a therapeutic approach in the management of AP. (Abstract shortened by UMI.) / Recent advance in basic research has revealed that the renin-angiotensin system (RAS) plays an important role in the pathogenesis of AP. In this regard, the present study aimed at investigating the effectiveness of RAS blockade in clinically relevant AP animal model and AP-associated systemic inflammation. More importantly, the underlying mechanistic pathways involved in angiotensin II (Ang II)-induced pro-inflammatory actions were elucidated using both in vivo and in vitro systems. / Results. Major components of RAS were up-regulated in obstructive pancreatitis model. Blockade of AT1 receptor attenuated pancreatic injury induced by the two models. Moreover, losartan could significantly ameliorate AP-associated systemic inflammation. Analysis of protein expression levels revealed that losartan treatment improved AP-associated elevation of NADPH oxidase p67 and p22 subunits. Double-immunostaining confirmed that expression of NADPH oxidase was localized to pancreatic acinar cells. AT1 receptor antagonism not only reduced oxidative stress but also suppressed nuclear factor kappaB (NFkappaB) activation, as evidenced by reversal effects on IkappaBbeta depletion, augmentation of phosphor NFkappaB p65, and enhanced nuclear kappaB binding activity. Blockade of AT1 receptor could also suppress the levels of kappaB-related protein expression, including intercellular adhesion molecule-1, cyclooxygenase-2, and IL-1. On the other hand, pancreatic mRNA and protein levels of IL-6 were enhanced by obstructive AP, which were antagonized by AT1 receptor blocker. Losartan treatment could reverse extracellular-regulated kinase (ERK) 1/2 and cAMP-responsive element binding protein (CREB) phosphorylation brought by obstructive AP. In vitro studies, exogenous application of Ang II induced ERK1/2 and CREB activation in AR42J cells. Concomitantly, IL-6 expression was augmented dose- and time-dependently in response to Ang II, which was reversed by treatment of AT1 receptor blocker (losartan) and ERK1/2 inhibitor (PD98059). Ang II induced NFkappaB activation was reversed by pre-treatment of AT1 receptor blocker and NADPH oxidase inhibitor but not ERK1/2 inhibitor in vitro. Moreover, Ang II-induced superoxide generation was detected. Treatment of antioxidant prevented Ang II-induced ERK1/2 activation. On top of these, in vitro experiments revealed that Ang II could sustain the activation of caerulein-induced NFkappaB and ERK1/2 in an AT1 receptor-mediated manner, but not secretagogue-induced hypersecretion. / Chan, Yuk Cheung. / Adviser: Po Siny Lzung. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3246. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 228-262). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Na+ sensitive hypertension in Dahl salt sensitive rats (Dahl S) or spontaneously hypertensive rats (SHR) is linked to intrinsic changes in the brain that favour increased Na+ entry into the cerebrospinal fluid (CSF) followed by increases in sympathetic hyperactivity and hypertension (Huang et al 2004). Similar responses are observed in salt resistant and Wistar rats that receive an intracerebroventricular (icv) infusion of Na+ rich artificial cerebrospinal fluid (aCSF) (Huang et al 2001, 2006). Downstream to increased CSF[Na+], a pathway has been described involving mineralocorticoid receptors (MRs), benzamil sensitive Na+ channels, “ouabain”, and angiotensin II type 1 receptors (AT1-R) (Huang et al 1998, Zhao et al 2001, Wang and Leenen 2003, Huang et al 2008). Blood pressure (BP) responses to increased CSF[Na+] may involve activation of AT1-R in the subfornical organ (SFO) as the BP response to injection of NaCl into a lateral ventricle can be blocked by AT1-R blockade in the SFO (Rohmeiss et al 1995a). The role of aldosterone and AT1-R in the SFO was investigated in mediating the BP and heart rate (HR) response to increases in CSF[Na+] and local [Na+]. Results show that infusion of 0.45M and 0.6M Na+ rich aCSF into the SFO increases BP but not HR. The BP is unchanged by infusion of a mannitol solution osmotically equivalent to 0.6M Na+ rich aCSF indicating that the SFO is Na+ sensitive. The BP response to a lower concentration of Na+ (0.45M) is enhanced by prior infusion of aldosterone while BP response to 0.6M is not further enhanced suggesting that the SFO may have maximal responsiveness to acute increases in [Na+] at 0.6M. The BP responses to Na+ rich aCSF in the SFO and the enhancement of those responses by aldosterone can be blocked by infusion of the AT1-R blocker Candesartan in the SFO. This response appears therefore to be mediated in the SFO through AT1-R activation, likely through Ang II release in the SFO. ICV infusion of Na+ rich aCSF increases BP but not HR and this response is partially blocked by infusion of the AT1-R blocker Candesartan in the SFO. This indicates that nearly half the BP responses to icv infusion of Na+ rich aCSF is mediated through AT1-R activation in the SFO. Lastly, contrary to icv, PVN and MnPO studies (Huang and Leenen 1996, Budzikowski and Leenen 2001, Gabor and Leenen 2009) ouabain in the SFO does not increase BP or HR. In conclusion, these results show that the SFO is Na+ sensitive and mediates half the BP responses to changes in CSF[Na+] through a mechanism that involves AT1-R activation. The SFO is further sensitized to Na+ by aldosterone presumably through its genomic effects. Lastly, ouabain in the SFO does not increase BP or HR suggesting that endogenous ouabain in the SFO is not involved in modulating BP or HR responses.

Angiotensin II inhibitors or Angiotensin Receptor Blockers (ARB s) are the most recent addition to the suite of antihypertensives. They are also one of the most expensive of the drug classes. Since the introduction of the first ARB on the market, the merits of ARB s have been investigated. The mechanism of action and indications are similar to ACE inhibitors thus comparisons have been done between the two classes to ascertain if there are any added benefits in using ARB s. This study was an analysis of out of hospital chronic medication claims from a managed care organisation in South Africa to view the utilisation pattern of ARB s and to establish if there were any indications for the choice of this specific drug class for the conditions hypertension and heart failure.. A managed care organisation aims to provide clinically appropriate and cost effective medication to its members. It is therefore important to investigate if there are any reasons for a more expensive drug to be used if there is a more cost effective alternative available. The medication claims for ARB s were investigated, in relation to ACE inhibitors to try and establish if there were any specific reasons for the use of ARB s. From the results obtained, it was evident that ACE inhibitors and ARB s were widely used within the managed care organisation and made up a high percentage of the amount spent on antihypertensive drugs. The gender utilisation patterns showed that more males used ACE inhibitors and ARB s for both hypertension and heart failure, although there were more females registered for these conditions within the organisation. The incidence of hypertension and heart failure was more prevalent in the over 45 year old age group and the use of these antihypertensive medications mirrored this. ARB s were the most expensive class of drugs used for hypertension and heart failure, and there was no reason found to support the specific use of these agents.

As espécies reativas de oxigênio (EROs) são intermediários de vias de sinalização que regulam eventos celulares relevantes na função de células musculares lisas vasculares como migração, proliferação e contração. A NADPH oxidase é a principal fonte enzimática de EROs com finalidade sinalizadora no sistema cardiovascular. Estudos do nosso grupo demonstraram que a proteína dissulfeto isomerase (PDI), uma chaperona redox do retículo endoplasmåtico é capaz de modular a geração de EROs e a ativação de vias de sinalização redox dependentes pela Ang II. Apesar dos recentes avanços na compreensão dos mecanismos que regulam a interação entre a PDI e NADPH oxidase, o papel desta chaperona nos efeitos biológicos relacionados a EROs, como a contração vascular, não estão esclarecidos. A inibição da resposta contrátil pelo DTNB, um oxidante de tióis sugere o envolvimento de proteínas contendo tióis como a PDI e a NADPH oxidase na contração de aortas isoladas estimuladas com Ang II. Estes resultados foram confirmados por experimentos que demonstraram a expressão de PDI em todas as camadas vasculares da aorta de ratos Wistar e uma co-localização desta proteína com a isoforma NOX-1. A inibição da PDI diminuiu a geração de EROs e a reatividade vascular induzida por Ang II e NOR independente da presença do endotélio. A investigação dos mecanismos envolvidos sugere um papel da PDI na mobilização de cálcio dos estoques intracelulares via NADPH oxidase. A ativação de MAP quinases contribuiu para aumentar a mobilização de cálcio intracelular em aortas estimuladas com Ang II e NOR. No entanto, a inibição da PDI reduziu a fosforilação da ERK 1/2 em aortas estimuladas com Ang II, mas não com NOR. A análise conjunta dos nossos resultados sugere que mecanismos redox dependentes e independentes estariam envolvidos na regulação da resposta contrátil à Ang II e NOR pela PDI. / The reactive oxygen species (ROS) are intermediates of signaling pathways which regulates cellular events relevant for the vascular smooth cells function as migration, proliferation and contraction.The NADPH oxidase is the main enzimatic source of ROS with the signaling purpose on the cardiovascular system. We previously demonstrated that the protein disulfide isomerase (PDI), a redox chaperone of endoplasmic reticulum, is able to modulate the ROS generation and the activation of signaling redox ways dependent of Ang II. Although the recent advances in the understanding of mechanisms that regulate the interaction of PDI and NADPH oxidase, the role of this chaperone in the biological effects related to ROS, as vascular contraction, are not well clarified. The inhibition of the contractile response by DTNB, an oxidant thiol, suggest the involvement of proteins containing thiols as the PDI and NADPH oxidase in the contraction of isolated aortas stimulated with Ang II. These results were confirmed by experiments that demonstrated the PDI expression in Wistar rats vascular layers and a co-localization of this protein with the NOX-1 isoform. The PDI inhibition decreased ROS generation and the Ang II and NOR induced vascular reactivity endothelium independent. The investigation of involved mechanisms suggest that one PDI role is the calcium mobilization from the intracellular storage by NADPH oxidase way. The MAPkinases activation contributed to increase de intracellualar calcium in stimulated aortas with AngII and NOR. However, the PDI inhibition reduced the ERK ½ fosforilation in AngII- stimulated aorta, but not with NOR. The analyses of all of our results suggests that dependent and independent redox mechanims were involved in the regulation of contractile response to Ang II and NOR by PDI.

Em roedores, a administração de Losartan (LO) durante a nefrogênese (primeiras duas semanas de vida) leva à insuficiência renal progressiva e, mais tardiamente, à hipertensão, indicando que a Angiotensina II (AII) é indispensável a uma nefrogênese adequada. Os mediadores intracelulares desse efeito são desconhecidos. Nós investigamos se o sistema NF-kB, que tem influência na embriogênese de outros tecidos, poderia ser um desses mediadores. Trinta e duas ratas Munich Wistar, cada uma amamentando 6 filhotes, foram divididas em dois grupos: C, sem tratamento, e PDTC, que receberam o inibidor do NF-kB Pirrolidina Ditiocarbamato (PDTC), 280 mg/kg/dia na água de beber durante 21 dias. A prole (C e PDTC), constituída de ratos machos, foi acompanhada até 10 meses de vida sem qualquer tratamento. Diferentemente do observado anteriormente com o LO, o PDTC não promoveu redução do número de néfrons nem albuminúria, indicando que o sistema NF-kB não participa crucialmente da nefrogênese. No entanto, os ratos que receberam o PDTC durante a lactação apresentaram hipertensão persistente, associada a hipertrofia de miócitos e a fibrose miocárdica. Para investigar a patogênese da hipertensão (que não se pode explicar por uma redução no número de néfrons), as expressões renais dos componentes do sistema renina-angiotensina (SRA) e dos transportadores tubulares foram determinadas por PCR em tempo real (qRT-PCR) aos 3 e 10 meses de vida. Aos 3 meses, a expressão de angiotensinogênio (AGT) e renina foram significativamente aumentadas no grupo PDTC vs C, indicando que uma ativação local do SRA pode explicar o desenvolvimento da hipertensão no grupo PDTC. No entanto, a expressão de todos os componentes do SRA examinados nos animais que receberam o PDTC durante a nefrogênese estava diminuída aos 10 meses, possivelmente devido a um mecanismo compensatório, sugerindo que a hipertensão foi mantida por outros mecanismos. No túbulo proximal, observou-se um aumento da expressão do transportador sódio/glicose isoforma 1 (SGLT1) (luminal) e sódio/bicarbonato (NBC) (basolateral), bem como um aumento numérico na expressão do trocador luminal sódio/hidrogênio isoforma 3 (NHE3), sugerindo que essas anormalidades podem estar envolvidas na patogênese da hipertensão nesses animais. Aos 10 meses, a expressão de todas as moléculas estava diminuída, sugerindo a participação de outros mecanismos na manutenção da hipertensão em longo prazo. A administração de PDTC pode representar um novo modelo de hipertensão essencial, possivelmente iniciada pela ativação local do SRA e por anormalidades no transporte de sódio no túbulo proximal e mantida em longo prazo por outros mecanismos. / Losartan treatment during late murine nephrogenesis (first 2 weeks of extrauterine life) causes progressive renal injury in adult life and, at more advanced stages, hypertension, indicating a physiologic action of angiotensin II on nephrogenesis. The possible intracellular pathways that might mediate this effect are unknown. We investigated the possibility that the NF-kB system, known to participate in the embryogenesis of other tissues, could be one of these mediators. Soon after delivery, thirty-two Munich-Wistar dams, each nursing 6 male pups, were divided in 2 groups: C, untreated, and PDTC, receiving the NF-kB inhibitor pyrrolidine dithiocarbamate (PDTC), 280 mg/kg/day in drinking water during 21 days. After weaning (at 25 days), the offspring (C and PDTC) were followed until 10 months of age with no further treatment. Unlike Losartan, neonatal PDTC treatment promoted no reduction in the number of nephrons and no abnormal albuminuria, indicating that the NF-kB system does not participate decisively in nephrogenesis. Nevertheless, rats that received PDTC during lactation exhibited stable hypertension associated with myocardial hypertrophy and fibrosis. To investigate the pathogenesis of hypertension, which cannot be ascribed to number of nephrons reduction, the renal expressions of the renin-angiotensin system (RAS) components and of several molecules involved in sodium transport were determined by qRT-PCR at 3 and 10 months of life. The renal expression of renin and angiotensinogen in PDTC-treated rats at 3 months of age was significantly higher in comparison with control, but lower than age-matched controls at 10 months of age, suggesting that, although hypertension may be initiated by a derangement in the RAS, it was maintained by other mechanisms in the long run. At 3 months of age, there was upregulation of the luminal sodium/glucose transporter and the basolateral sodium/bicarbonate transporter at the proximal tubule, as well as a numerically higher expression of the luminal sodium/hydrogen exchanger, suggesting that these abnormalities might also be related to the pathogenesis of hypertension in these rats. At 10 months of age, however, the expression of all these transporters was reduced, suggesting that none of them was responsible for the long-term maintenance of high blood pressure. Neonatal PDTC administration represents a new model of essential hypertension, possibly related to local renal activation of the RAS and to deranged sodium transport at the proximal tubule. In the long run, hypertension must be maintained by other mechanisms.

by Pui-fan Wong. / "December 2001." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2001. / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

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

1 / Sarah Elizabeth Galvez

Das Renin-Angiotensin-Aldosteron-System (RAAS) reguliert den Blutdruck und den Wasser- und Elektrolythaushalt des Körpers. Angiotensin II (Ang II), das aktive Peptid des RAAS, bewirkt eine Vasokonstriktion und in höheren Konzentrationen Bluthochdruck. Epidemiologische Studien haben gezeigt, dass eine Verbindung zwischen Hypertonie und dem gehäuften Auftreten von Krebs besteht. Eine Metaanalyse von 13 Fall-Kontroll-Studien konnte einen Zusammenhang zwischen Hypertonie und einem erhöhten Risiko, an einem Nierenzellkarzinom zu erkranken nachweisen. In vitro-Studien und Studien an der isolierten Niere konnten bereits genotoxische Effekte des blutdruckregulierenden Hormons Ang II zeigen. Zielsetzung dieser Arbeit war es, zunächst in vivo zu prüfen, ob steigende Ang II-Konzentrationen einen Einfluss auf die genomische Stabilität von Nieren- und Herzzellen besitzen. Hierzu wurden im Dosisversuch männliche C57BL/6-Mäuse mit osmotischen Minipumpen ausgestattet, die Ang II in vier verschiedenen Konzentrationen zwischen 60 ng/kg min und 1 µg/kg min über einen Zeitraum von 28 Tagen abgeben sollten. Während des Versuchszeitraums fanden regelmäßige, nicht-invasive Blutdruckmessungen an der Maus statt. Die Behandlung mit Ang II führte zu einem signifikanten Anstieg des Blutdrucks und zu histopathologischen Veränderungen der Glomeruli und des Tubulussystems, was sich in einer verschlechterten Albumin-Ausscheidung wiederspiegelte. Außerdem induzierte die Behandlung mit Ang II die dosisabhängige Bildung von reaktiven Sauerstoffspezies, DNA-Doppelstrangbrüchen und oxidativer DNA-Schäden. Diese Parameter waren bereits in Tieren erhöht, die keinen Bluthochdruck entwickelten und stiegen mit der höchsten Ang II-Konzentration noch an, obwohl hier im Vergleich zur Vorgängergruppe, die eine geringere Ang II-Konzentration erhielt, kein höherer Blutdruck vorlag. Diese Beobachtung deutet auf eine mögliche Unabhängigkeit des entstandenen Schadens vom Bluthochdruck hin und lenkt die Aufmerksamkeit auf Ang II als genomschädigenden Faktor. Der folgende Interventionsversuch sollte Aufschluss über die mögliche blutdruckunabhängige genomschädigende Wirkung von Ang II geben. Dazu wurden C57BL/6-Mäuse neben der Ang II-Behandlung in einer Konzentration von 600 ng/kg min zusätzlich über einen Zeitraum von 28 Tagen mit 5 verschiedenen Substanzen behandelt: Candesartan, Ramipril, Hydralazin, Eplerenon und Tempol. Candesartan ist ein Ang II-Rezeptor-Antagonist, der selektiv den AT1-Rezeptor blockiert. Ramipril wirkt als Hemmer des Angiotensin-Konversions-Enzyms und verhindert die Bildung von endogenem Ang II aus Ang I. Hydralazin, als Vasodilatator, greift nicht in das Renin-Angiotensin-Aldosteron-System ein. Eplerenon blockiert als selektiver Aldosteronantagonist den Mineralkortikoidrezeptor. Tempol wirkt als Antioxidans. Die Behandlung mit Ang II in einer Konzentration von 600 ng/kg min im Interventionsversuch führte zur Hochregulierung der NADPH-Oxidase 4 und zur Produktion reaktiver Sauerstoffspezies in der Niere und im kardiovaskulären Gewebe. Der entstandene oxidative Stress führte wiederum zu DNA-Schäden und einer Aktivierung der Transkriptionsfaktoren Nrf2 und NF-B. Nrf2-vermittelt wurde die Induktion antioxidativer Gene ausgelöst, was allerdings nicht ausreichend war, um vor Ang II-induzierten ROS und DNA-Schäden zu schützen. Eine längerfristige NF-B-Aktivierung durch hohe Ang II-Spiegel kann das Überleben und die Proliferation von Zellen, die DNA-Schäden in Form von Doppelstrangbrüchen tragen, fördern, was eine Tumor-initiierende Wirkung haben könnte. Die beschriebenen Effekte erhöhter Ang II-Spiegel konnten durch die Intervention mit dem AT1-Rezeptorblocker Candesartan verhindert werden, was die Beteiligung des Rezeptors nachweist. Eine blutdruckunabhängige, genomschädigende Wirkung von Ang II konnte leider durch die Intervention mit Hydralazin nicht verdeutlicht werden, da die erwünschte langfristige Blutdrucksenkung ausblieb. Allerdings zeigte die Intervention mit Tempol eine Abnahme an oxidativem Stress und DNA-Schäden trotz ausbleibender Blutdrucksenkung. Die Bedeutung von ROS in der Bildung von DNA-Schäden und die Unabhängigkeit dieser Schäden vom Blutdruck konnten somit hervorgehoben werden. Die Tatsache, dass die Intervention mit Ramipril den Blutdruck nicht senken konnte, der oxidative Stress und die DNA-Schäden durch mögliche antioxidative Eigenschaften aber vermindert wurden, unterstützt diese Beobachtung. Die Intervention mit Eplerenon führte zum Teil zu einer Verminderung an ROS und DNA-Schäden, brachte diese Parameter aber nicht auf Kontrollniveau zurück. Somit ist eine Beteiligung von Aldosteron nicht auszuschließen. / The renin-angiotensin-aldosterone system (RAAS) regulates blood pressure, water balance and electrolyte metabolism. Angiotensin II (Ang II), the reactive peptide of RAAS, causes vasoconstriction and, in higher concentrations, increased blood pressure. Epidemiological studies found an increased cancer incidence in hypertensive patients. A meta-analysis of 13 longitudinal studies revealed a connection between hypertension and a higher risk to develop kidney cancer. In vitro studies and studies of the isolated mouse kidney already showed genotoxic effects of Ang II. First, the aim of the study was to investigate in vivo the effect of increasing concentrations of Ang II on the genomic stability of kidney and heart cells. Therefore, male C57/BL6 mice were equipped with osmotic mini pumps, delivering Ang II in four different concentrations between 60 ng/kg min and 1 µg/kg min during 28 days. During the 4 weeks blood pressure was measured non-invasively. Treatment with Ang II raised the blood pressure significantly and led to histopathological changes of glomeruli and tubuli, reflecting an impaired albumin-excretion. Furthermore, the formation of reactive oxygen species (ROS), DNA double strand breaks and oxidative DNA damage was induced dose-dependently by Ang II. These parameters were already increased in animals with normal blood pressure and were further increased by the highest Ang II concentration, although blood pressure was not higher than in the precursor group, which received less Ang II. These observations might hint to a possible independency of the Ang II-induced damage from the blood pressure, focusing on Ang II as the genotoxic substance. The following intervention experiment was conducted to investigate the possible blood pressure independent genotoxic effects of Ang II. Besides the treatment with Ang II in a concentration of 600 ng/kg min, C57BL/6 mice were additionally treated with 5 different interventions: candesartan, an AT1 receptor antagonist, ramipril, a angiotensin-converting-enzyme blocker, hydralazine, a vasodilator, eplerenone, a mineralocorticoid receptor blocker and tempol, an antioxidant. In the intervention experiment, Ang II treatment in a concentration of 600 ng/kg min caused an up-regulation of NOX 4 resulting in the production of ROS in the kidney and heart. The oxidative stress led to the formation of DNA damage and to an activation of the transcription factors Nrf2 and NF-B. The induction of Nrf2 was accompanied by up-regulation of antioxidative enzymes, which, however, were not able to defend against ROS-production and DNA damage. A long-term activation of NF-B by high Ang II levels can promote the survival and proliferation of cells with DNA damage in form of DNA double strand breaks, probably initiating carcinogenesis. The AT1 receptor blocker candesartan could prevent the Ang II-induced damage, demonstrating the involvement of the Ang II receptor. The intervention with hydralazine failed to show a genotoxic effect of Ang II independent of the blood pressure, since a long-term decrease of blood pressure was missing. However, despite of the high blood pressure, the intervention with tempol was able to prevent oxidative stress and DNA-damage. The importance of ROS in the formation of DNA damage and an independency of this damage from the increased blood pressure was shown. The fact that, although not lowering blood pressure, ramipril was able to reduce oxidative stress and DNA damage by possible antioxidative properties, supported this observation. Eplerenone led to slight decrease in ROS and DNA damage showing the possible involvement of aldosterone. Ang II contributes to damage detected in the kidney and in the heart during high blood pressure, probably initiating cancer. The involvement of ROS for the formation of DNA damage and the independency of this damage from the increased blood pressure was shown by the effects of the antioxidant tempol. We could demonstrate that the importance of an AT1 receptor antagonist in the treatment of high blood pressure plays a leading role. Compared to other antihypertensive therapies, treatment with a sartan is the best option. Starting at an early stage with this therapy, a long-term damage, induced by Ang II, could be avoided.