Identification of Periostin as a Critical Marker of Progression/Reversal of Hypertensive Nephropathy

Progression of chronic kidney disease (CKD) is a major health issue due to persistent accumulation of extracellular matrix in the injured kidney. However, our current understanding of fibrosis is limited, therapeutic options are lacking, and progressive degradation of renal function prevails in CKD patients. Uncovering novel therapeutic targets is therefore necessary

A Novel Role of Semaphorin 3C in Modulating Systemic and Renal Hemodynamics

International audienceBackground: Alterations of renal hemodynamics play an essential role in renal homeostasis and kidney diseases. Recent data indicated that semaphorin 3C (SEMA3C), a secreted glycoprotein involved in vessel development, can modulate renal vascular permeability in acute kidney injury, but whether and how it might impact systemic and renal hemodynamics is unknown. Objectives: The objective of the study was to explore the effect of SEMA3C on systemic and renal hemodynamics. Methods: SEMA3C recombinant protein was administered intravenously in two-month-old wild-type mice, and the variations of mean arterial pressure, heart rate, renal blood flow, and renal vascular resistance were measured and analyzed. Results: Acute administration of SEMA3C induced (i) systemic hemodynamic changes, including mean arterial pressure decrease and heart rate augmentation; (ii) renal hemodynamic changes, including reduced vascular resistance and elevated renal blood flow. Continuous perfusion of SEMA3C had no significant effect on systemic or renal hemodynamics. Conclusion: SEMA3C is a potent vasodilator affecting both systemic and renal hemodynamics in mice

Angiotensin II Activates Collagen Type I Gene in the Renal Vasculature of Transgenic Mice During Inhibition of Nitric Oxide Synthesis

International audienceBackground —Hypertension is frequently associated with renal vascular fibrosis. The purpose of this study was to investigate whether angiotensin II (Ang II) is involved in this fibrogenic process. Methods and Results —Experiments were performed on transgenic mice harboring the luciferase gene under the control of the collagen I-α 2 chain promoter [procolα 2 (I)]. Hypertension was induced by chronic inhibition of NO synthesis ( N G -nitro- l -arginine methyl ester, L-NAME). Procolα 2 (I) activity started to increase in the renal vasculature after 4 weeks of L-NAME treatment ( P <0.01) and at 14 weeks reached 3- and 8-fold increases over control in afferent arterioles and glomeruli, respectively ( P <0.001). Losartan, an AT 1 receptor antagonist, given simultaneously with L-NAME prevented the increase of procolα 2 (I) levels and attenuated the development of renal vascular fibrosis without normalizing systolic pressure increase. Because we found previously that endothelin mediated renal vascular fibrosis in the L-NAME model, the interaction between Ang II, endothelin, and procolα 2 (I) was investigated in ex vivo and short-term in vivo experiments. In both conditions, the Ang II–induced activation of procolα 2 (I) in renal cortex was blocked by an endothelin receptor antagonist. Conclusions —During chronic inhibition of NO, the collagen I gene becomes activated, leading to the development of renal vascular fibrosis. Ang II is a major player in this fibrogenic process, and its effect on collagen I gene is independent of systemic hemodynamics and is at least partly mediated by the profibrogenic action of endothelin

Angiotensin II Activates Collagen Type I Gene in the Renal Vasculature of Transgenic Mice During Inhibition of Nitric Oxide Synthesis

International audienceBackground —Hypertension is frequently associated with renal vascular fibrosis. The purpose of this study was to investigate whether angiotensin II (Ang II) is involved in this fibrogenic process. Methods and Results —Experiments were performed on transgenic mice harboring the luciferase gene under the control of the collagen I-α 2 chain promoter [procolα 2 (I)]. Hypertension was induced by chronic inhibition of NO synthesis ( N G -nitro- l -arginine methyl ester, L-NAME). Procolα 2 (I) activity started to increase in the renal vasculature after 4 weeks of L-NAME treatment ( P <0.01) and at 14 weeks reached 3- and 8-fold increases over control in afferent arterioles and glomeruli, respectively ( P <0.001). Losartan, an AT 1 receptor antagonist, given simultaneously with L-NAME prevented the increase of procolα 2 (I) levels and attenuated the development of renal vascular fibrosis without normalizing systolic pressure increase. Because we found previously that endothelin mediated renal vascular fibrosis in the L-NAME model, the interaction between Ang II, endothelin, and procolα 2 (I) was investigated in ex vivo and short-term in vivo experiments. In both conditions, the Ang II–induced activation of procolα 2 (I) in renal cortex was blocked by an endothelin receptor antagonist. Conclusions —During chronic inhibition of NO, the collagen I gene becomes activated, leading to the development of renal vascular fibrosis. Ang II is a major player in this fibrogenic process, and its effect on collagen I gene is independent of systemic hemodynamics and is at least partly mediated by the profibrogenic action of endothelin

Anaesthesia-Induced Transcriptomic Changes in the Context of Renal Ischemia Uncovered by the Use of a Novel Clamping Device

International audienceIschemia is a common cause of acute kidney injury worldwide, frequently occurring in patients undergoing cardiac surgery or admitted to the intensive care unit (ICU). Thus, ischemia-reperfusion injury (IRI) remains one of the main experimental models for the study of kidney diseases. However, the classical technique, based on non-traumatic surgical clamps, suffers from several limitations. It does not allow the induction of multiple episodes of acute kidney injury (AKI) in the same animal, which would be relevant from a human perspective. It also requires a deep and long sedation, raising the question of potential anaesthesia-related biases. We designed a vascular occluding device that can be activated remotely in conscious mice. We first assessed the intensity and the reproducibility of the acute kidney injury induced by this new device. We finally investigated the role played by the anaesthesia in the IRI models at the histological, functional and transcriptomic levels. We showed that this technique allows the rapid induction of renal ischemia in a repeatable and reproducible manner, breaking several classical limitations. In addition, we used its unique specificities to highlight the renal protective effect conferred by the anaesthesia, related to the mitigation of the IRI transcriptomic program

Notch3 orchestrates epithelial and inflammatory responses to promote acute kidney injury

International audienceAcute kidney injury is a major risk factor for subsequent chronic renal and/or cardiovascular complications. Previous studies have shown that Notch3 was de novo expressed in the injured renal epithelium in the early phases of chronic kidney disease. Here we examined whether Notch3 is involved in the inflammatory response and the epithelial cell damage that typifies ischemic kidneys using Notch3 knockout mice and mice with short-term activated Notch3 signaling (N3ICD) in renal epithelial cells. After ischemia/reperfusion, N3ICD mice showed exacerbated infiltration of inflammatory cells and severe tubular damage compared to control mice. Inversely, Notch3 knockout mice were protected against ischemia/reperfusion injury. Renal macrophages derived from Notch3 knockout mice failed to activate proinflammatory cytokines. Chromatin immunoprecipitation analysis of the Notch3 promoter identified NF-κB as the principal inducer of Notch3 in ischemia/reperfusion. Thus, Notch3 induced by NF-κB in the injured epithelium sustains a proinflammatory environment attracting activated macrophages to the site of injury leading to a rapid deterioration of renal function and structure. Hence, targeting Notch3 may provide a novel therapeutic strategy against ischemia/reperfusion and acute kidney injury by preservation of epithelial structure and disruption of proinflammatory signaling

Role of renal urothelium proliferation in the onset of calcium oxalate stones

International audienceBackgroundMost mice kidney stone models induce nephrocalcinosis rather than urolithiasis.Materials and methodsC57B6 mice under vitamin D and water containing 4% hydroxyl-L-proline, ammonium chloride (0.28M) and calcium (0.25%) were follow up until day 42. A group receiving Fibroblast Growth Factor 7 (FGF7 i.p. once a week), a urothelial cell mitogen was compared to control group. Localization and identification of crystal deposits were performed with polarizing microscopy, infrared imager and Scanning Electron Microscopy. Urothelial and tubular phenotypes were studied by immunohistochemistry, immunofluorescence and RT PCR.ResultsCalcium oxalate monhydrate (COM) deposits in fornices were detected in all kidneys as soon as day 14 with very few crystals in tubules. On day 21, crystal number was increased in FGF7 compared to control group. Though osteopontin (OPN) was unregulated and detected in urothelial cells, de novo expression of CD44 (osteopontin receptor) receptor was induced only in proliferating urothelial cells either induced by FGF7 or by long standing urine crystal exposure altogether with a loss of apical uroplakines III expression. ConclusionOur model seems interesting to study in KO mice, in order to investigate the critical events leading to urolithiasis. Our data show that urothelial cells proliferation promotes renal crystal retention especially within fornices, probably through different processes involving specific and non-specific crystal adhesion, and thus appears per se as a relevant risk factor for stone formation

Administration of Recombinant Soluble Urokinase Receptor <em>Per Se</em> Is Not Sufficient to Induce Podocyte Alterations and Proteinuria in Mice

Circulating levels of soluble forms of urokinase-type plasminogen activator receptor (suPAR) are generally elevated in sera from children and adults with FSGS compared with levels in healthy persons or those with other types of kidney disease. In mice lacking the gene encoding uPAR, forced increases in suPAR concentration result in FSGS-like glomerular lesions and proteinuria. However, whether overexpression of suPAR, per se, contributes to the pathogenesis of FSGS in humans remains controversial. We conducted an independent set of animal experiments in which two different and well characterized forms of recombinant suPAR produced by eukaryotic cells were administered over the short or long term to wild-type (WT) mice. In accordance with the previous study, the delivered suPARs are deposited in the glomeruli. However, such deposition of either form of suPAR in the kidney did not result in increased glomerular proteinuria or altered podocyte architecture. Our findings suggest that glomerular deposits of suPAR caused by elevated plasma levels are not sufficient to engender albuminuria