16^th European Nephrology Conference October 02-03, 2017 Barcelona, Spain

Biography:

Jia L Zhuo is a Full Professor and the Director of Receptor and Signal Transduction Laboratory in the Department of Pharmacology and Toxicology at the University of Mississippi Medical Center, Jackson, USA. He has over 30 years of sponsored research experience on the roles of Endocrine, Paracrine, and Intracrine Angiotensin II in the kidney and hypertension, supported by National Health and Medical Research Council of Australia (NHMRC) and National Institute of Health (NIH). He has authored >110 peer-reviewed articles and book chapters with many recognized by editorials, cover highlights, and the Faculty of 1000. He is a Fellow of The American Association for The Advancement of Science (AAAS), American Heart Association (AHA), and American Society of Nephrology (ASN), a permanent member for NIH/Center for Scientific Review Hypertension and Microcirculation Study Section. His research is currently supported by grants from National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institute of General Medical Sciences (NIGMS), and National Heart, Lung, and Blood Institute (NHLBI) respectively. 

Abstract:

It is well established that a physiological pressure natriuretic response plays a key role in maintaining normal blood pressure and body salt and fluid balance, but the mechanisms underlying the pressure natriuresis response and its resetting to higher pressures in hypertension remain incompletely understood. Here we used wild-type (WT), global (Nhe3^-/-), kidney- (tgNhe3^-/-) or proximal tubule-specific knockout (PT-Nhe3^-/-) of the Na⁺/H⁺ exchanger 3 (NHE3) to test the hypothesis that NHE3 in the proximal tubule of the kidney plays a critical role in the pressure natriuretic response and the development of angiotensin II (ANG II)-induced hypertension. 3 groups (n=8-12 per group) of adult male WT, Nhe3^-/-, tgNhe3^-/-_, and PT-Nhe3^-/- mice (n=8-12 per group) were prepared for the standard pressure natriuretic experiment and ANG II-induced hypertension, respectively. The pressure natriuresis response was studied using the mesenteric and celiac occlusion technique to elevate renal perfusion pressure equally by 25 mmHg in all strains of mice. Under basal conditions, Nhe3^-/-, tgNhe3^-/-, and PT-Nhe3^-/- mice had significantly lower systolic blood pressure (p<0.01) and mean intra-arterial blood pressure than WT mice (p<0.01). 24 h fecal Na⁺ excretion was significantly increased (p<0.01), whereas 24 h urinary Na⁺ excretion was significantly reduced in both Nhe3^-/- and tgNhe3^-/- mice (p<0.01). However, no difference was found in fecal Na⁺ excretion between WT and PT-Nhe3^-/- mice, whereas 24 h urinary Na⁺ excretion was significantly increased in PT-Nhe3^-/- mice (p<0.01). In response to increased renal perfusion pressure, the pressure natriuresis response increased 4-folds in WT mice (p<0.01), and only 2-fold in Nhe3^-/- and tgNhe3^-/- mice (p<0.01). By comparison, the pressure natriuresis response increased 7-folds in PT-Nhe3^-/- mice (p<0.01). To determine the role of NHE3 in ANG II-induced hypertension, ANG II was infused in WT, Nhe3^-/-, tgNhe3^-/-_, and PT-Nhe3^-/- mice for 2 weeks (1.5 mg/kg/day, i.p.). ANG II induced robust hypertension in WT mice (p<0.01), as expected, but the hypertensive response to ANG II was significantly attenuated in global Nhe3^-/-, kidney-selective tgNhe3^-/-, and PT-Nhe3^-/- mice. Our results support the hypothesis that NHE3 in the proximal tubule of the kidney plays a key role in the regulation of physiological pressure natriuretic responses and the development of ANG II-induced hypertension.

Biography:

Nicolas Gilles has completed his PhD at Paris Descartes University. He is pioneering the investigation of animal toxins acting on GPCRs, the largest therapeutic target class. His strongest expertise lies in Receptor Pharmacology, Synthetic Production of Disulfide-Linked Animal Toxins and in vivo experiments. He has published more than 70 papers and three patents. His strongest interest is now to stimulate the therapeutic development of animal toxins for the benefit of human health. 

Abstract:

Autosomal dominant polykystose kidney disease affect 1 over 1,000 peoples, leading to end-stage renal disease. The blockage of the Vasopressin type 2 receptor (V2R) is a validated therapeutic line in human by preventing the vasopressin-induced elevation in intracellular cAMP concentration. Currently, only tolvaptan (jirnac) succeed to reach the market but with many concerns. Scorpions, spiders, snakes, conus, insects, miriapodes are often seen as dangerous, frightening and ugly animals. Their venoms are extremely rich in toxins historically identified for their toxicities. We believe that animal toxins are highly valuable in the context of human use and drug development. We developed a specific strategy in order to identified toxins with the purpose of discover novel drug candidates. Mambaquaretin was discovered in the green mamba venom by a bioguidage strategy directed against the V2R. This toxin belongs to the Kunitz fold peptide family, and its displays a nanomolar affinity for the V2R. Molecular pharmacological essays demonstrated that mambaquaretin is the most selective V2R antagonist. Daily injection of 13 µg of mambaquaretin to pcy mice, a model of juvenile recessive kidney polykystose, over a period of 99 days, allowed the drug candidate to inhibit cyst growth area by almost 30%. No apparent toxicity was observed in treated animals. Mambaquaretin is a promising drug candidate with an original mode of action. Molecular modelling and structure function analysis allowed us to propose a model of interaction of the mambaquaretin/V2R complex.

Biography:

Stefanie Steiger has studied Bioengineering at the Martin-Luther University Halle, Germany from 2000 until 2006 followed by a working contract at Boehringer Ingelheim for two years. In 2008, she completed her PhD in Medical Science at Malaghan Institute of Medical Research, Victoria University Wellington, New Zealand, and two years of Post-doctoral fellowship. She moved to University of Munich, Germany in 2014, where she established her own group. Her research focus is the bidirectional impact of uric acid and chronic kidney disease.

Abstract:

Uric acid (UA) and chronic kidney disease (CKD) have a bidirectional relationship. The development of CKD has been associated with increased UA levels due to decreased urinary excretion of UA and resultant hyperuricemia, a major risk factor for gouty arthritis. Mild CKD often leads to an increased prevalence of gouty arthritis, as prospective observational studies have demonstrated, whereas advanced CKD and end-stage renal disease (ESRD) leads to a drop in the prevalence despite massive hyperuricemia. Conversely, there is evidence that gout and associated hyperuricemia may independently impair kidney function. Hyperuricemia in the presence or absence of gout, the use of gout medications, and the deposition of UA microcrystals in the medullary interstitium can potentially be harmful to the kidney, increase the risk for developing CKD, and are progressive factors for worsening CKD. However, these clinical data are conflicting and currently, there is no ideal animal model available to investigate the molecular effects of UA and gout in CKD in more detail, which raises the following unanswered questions: What is chicken-and-egg, CKD causes hyperuricemia but does hyperuricemia also lead to the progression of CKD? and by what mechanism? Which further raises the question: do CKD patients profit from uricostatic pharmacotherapy? What are the molecular mechanisms behind an increased prevalence of gouty arhtritis in mild CKD and a drop-in prevalence in advanced CKD? Does hyperuricemia affect UA crystal-induced inflammation by priming inflammatory cells, and is therefore responsible for the lower risk of acute gouty arthritis with advanced CKD and ESRD? These questions will be addressed in the oral presentation with supportive clinical data and an in vivo animal model.

Biography:

Mesothelial-to-mesenchymal transition (MMT) is an auto-regulated physiological process of tissue repair that in uncontrolled conditions such as peritoneal dialysis (PD) can lead to peritoneal fibrosis. The maximum expression of peritoneal fibrosis induced by PD fluids and other peritoneal processes is the encapsulating peritoneal sclerosis (EPS) for which no specific treatment exists. Tamoxifen a synthetic estrogen has successfully been used to treat retroperitoneal fibrosis and EPS associated with PD. Hence, we used in vitro and animal model approaches to evaluate the efficacy of Tamoxifen to inhibit the MMT as a trigger of peritoneal fibrosis. In vitro studies were carried out using omentum-derived mesothelial cells (MCs) and effluent-derived MCs. Tamoxifen blocked the MMT induced by transforming growth factor (TGF)-β1, as it preserved the expression of E-cadherin and reduced the expression of mesenchymal-associated molecules such as Snail, fibronectin, collagen-I, α-smooth muscle actin, and matrix metalloproteinse-2. Tamoxifen-treatment preserved the fibrinolytic capacity of MCs treated with TGF-β1 and decreased their migration capacity. Tamoxifen did not reverse the MMT of non-epitheliod MCs from effluents, but it reduced the expression of some mesenchymal molecules. In mice PD model, Tamoxifen significantly reduced peritoneal thickness, angiogenesis, invasion of the compact zone by mesenchymal MCs and improved peritoneal function. Tamoxifen also decreased the accumulation advanced glycation end-products and reduced the effluent levels of VEGF and leptin. These results demonstrate that Tamoxifen is a therapeutic option to treat peritoneal fibrosis, and that its protective effect is mediated via modulation of MMT process.

Abstract:

Mesothelial-to-mesenchymal transition (MMT) is an auto-regulated physiological process of tissue repair that in uncontrolled conditions such as peritoneal dialysis (PD) can lead to peritoneal fibrosis. The maximum expression of peritoneal fibrosis induced by PD fluids and other peritoneal processes is the encapsulating peritoneal sclerosis (EPS) for which no specific treatment exists. Tamoxifen a synthetic estrogen has successfully been used to treat retroperitoneal fibrosis and EPS associated with PD. Hence, we used in vitro and animal model approaches to evaluate the efficacy of Tamoxifen to inhibit the MMT as a trigger of peritoneal fibrosis. In vitro studies were carried out using omentum-derived mesothelial cells (MCs) and effluent-derived MCs. Tamoxifen blocked the MMT induced by transforming growth factor (TGF)-β1, as it preserved the expression of E-cadherin and reduced the expression of mesenchymal-associated molecules such as Snail, fibronectin, collagen-I, α-smooth muscle actin, and matrix metalloproteinse-2. Tamoxifen-treatment preserved the fibrinolytic capacity of MCs treated with TGF-β1 and decreased their migration capacity. Tamoxifen did not reverse the MMT of non-epitheliod MCs from effluents, but it reduced the expression of some mesenchymal molecules. In mice PD model, Tamoxifen significantly reduced peritoneal thickness, angiogenesis, invasion of the compact zone by mesenchymal MCs and improved peritoneal function. Tamoxifen also decreased the accumulation advanced glycation end-products and reduced the effluent levels of VEGF and leptin. These results demonstrate that Tamoxifen is a therapeutic option to treat peritoneal fibrosis, and that its protective effect is mediated via modulation of MMT process.

Biography:

Xiao C Li is a Senior Research Scientist in the Receptor and Signal Transduction Laboratory in the Department of Pharmacology and Toxicology at University of Mississippi Medical Center, Jackson, Mississippi, USA. She has received Postdoctoral research training in Cardiovascular Pharmacology at Monash University, Melbourne, Australia, and in Molecular Pharmacology at University of Michigan, USA respectively. She has more than 20 years of research experience in G Protein-Coupled Receptor Pharmacology and angiotensin II-dependent hypertension, and authored more than 40 peer-reviewed articles in high impact journals such as Hypertension, Kidney International, Clinical Science, Biochemical Pharmacology, American Journal of Physiology, and Pharmacological Research etc., and a book in the renin-angiotensin system research field, and many were recognized by editorial commentaries, color cover highlights, and the faculty of 1000. Currently, she is working as a Co-Investigator in several research grants from National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), National Institute of General Medical Sciences (NIGMS), and National Heart, Lung, and Blood Institute (NHLBI). 

Abstract:

We have recently shown that angiotensin (ANG II)-induced hypertension was attenuated in mice with global (Nhe3^-/-) and Nhe3^-/- mice with transgenic rescue of the NHE3 gene selectively in small intestines (tgNhe3^-/-), suggesting a significant role of NHE3 in the development of ANG II-dependent hypertension. The present study tested whether the pharmacological inhibition of NHE3 mainly in the proximal tubule of the kidney attenuates ANG II-dependent hypertension induced by a slow pressor dose of ANG II supplemented with 2% high salt diet. 9 groups (n=6-12) of adult male C57BL/6J mice were infused with or without ANG II (500 μg/kg/day, i.p. via mini pump) and supplemented with or without a 2% NaCl diet to slowly and moderately increase blood pressure (SBP) in 2 weeks. ANG II alone increased SBP from 116±2 mmHg to 140±2 mmHg (p<0.01), and supplement of ANG II with a 2% NaCl diet further increased SBP to 147±4 mmHg (p<0.05). Concurrent treatment with an orally active, absorbable NHE3 inhibitor AVE0657 (Sanofi-Aventis; 20 mg/kg/day, p.o.) significantly decreased SBP to 125±4 mmHg in ANG II-infused mice (p<0.01), and to 134±6 mmHg in ANG II-infused mice supplemented with 2% NaCl (p<0.01), respectively. Further treatment with AVE0657 and losartan, an AT₁ receptor blocker (20 mg/kg/day, p.o.), completely normalize SBP in mice treated with ANG II and 2% NaCl to control (115±5 mmHg, p<0.01). AVE0657 significantly increased 24 h urinary Na⁺ excretion (p<0.01) but had no effect on 24 h fecal Na⁺ excretion in control or ANG II-infused mice. These results provide preclinical evidence that orally absorbable NHE3 inhibitors may be pharmacologically beneficial to treat ANG II-dependent hypertension by inhibiting NHE3 and Na⁺ reabsorption in the proximal tubule of the kidney.

Biography:

Nariaki Asada graduated from Kyoto University. He researched a new testing on a diaper for urinary tract infection at pediatrics department of Ota Memorial Hospital. He is currently persuing PhD at pediatrics department of Keio University School of Medicine. Current research interests are anemia of prematurity and polycythemia in patients born preterm with low birth weight. 

Abstract:

Patient 1 and 2, born at 25 weeks of gestation with birth weight of 466 g and 728 g, showed mild proteinuria at age 6 and 8 years, respectively. In association with increasing proteinuria and blood pressure (BP), polycythemia developed in adolescence. Patient 1 and 2 underwent renal biopsy at age 15 and 18 years, when their BP was 143/59 and 137/82 mmHg, eGFR 90 and 114 ml/min/m², hemoglobin 18.7 and 19.0 g/ dL, erythropoietin (EPO) 24.5 and 17.8 U/L, respectively. Polycythemia was considered to be due to increased EPO. Light microscopy showed glomerular hypertrophy, and focal segmental glomerulosclerosis without significant fibrosis. Immunohistochemical staining with CD31 or CD34 antibody revealed PTC rarefaction.

Clinical study: Thirty-six patients with a history of extremely LBW were retrospectively analyzed (male 17, female 19; age at analysis 4-19 years; birth weight 316-998 g; gestational age 22-32 weeks). Twelve patients showed hemoglobin levels more than 2 SD above the mean (polycythemia group, male 7, female 5; age at finding 2-16 years). Polycythemia was associated with lower eGFR (73 ml/min/1.73m² vs 106 ml/min/1.73m²) and smaller birth weight (619 g vs 802 g).

Conclusions: Polycythemia can be observed in patients born preterm with extremely low birth weight, and associated with low eGFR.