SGLT2 inhibition effect on salt-induced hypertension, RAAS, and Na+ transport in Dahl SS rats.

Na+-glucose cotransporter-2 (SGLT2) inhibitors are the new mainstay of treatment for diabetes mellitus and cardiovascular diseases. Despite the remarkable benefits, the molecular mechanisms mediating the effects of SGLT2 inhibitors on water and electrolyte balance are incompletely understood. The goal of this study was to determine whether SGLT2 inhibition alters blood pressure and kidney function via affecting the renin-angiotensin-aldosterone system (RAAS) and Na+ channels/transporters along the nephron in Dahl salt-sensitive rats, a model of salt-induced hypertension. Administration of dapagliflozin (Dapa) at 2 mg/kg/day via drinking water for 3 wk blunted the development of salt-induced hypertension as evidenced by lower blood pressure and a left shift of the pressure natriuresis curve. Urinary flow rate, glucose excretion, and Na+- and Cl--to-creatinine ratios increased in Dapa-treated compared with vehicle-treated rats. To define the contribution of the RAAS, we measured various hormones. Despite apparent effects on Na+- and Cl--to-creatinine ratios, Dapa treatment did not affect RAAS metabolites. Subsequently, we assessed the effects of Dapa on renal Na+ channels and transporters using RT-PCR, Western blot analysis, and patch clamp. Neither mRNA nor protein expression levels of renal transporters (SGLT2, Na+/H+ exchanger isoform 3, Na+-K+-2Cl- cotransporter 2, Na+-Cl- cotransporter, and α-, ß-, and γ-epithelial Na+ channel subunits) changed significantly between groups. Furthermore, electrophysiological experiments did not reveal any difference in Dapa treatment on the conductance and activity of epithelial Na+ channels. Our data suggest that SGLT2 inhibition in a nondiabetic model of salt-sensitive hypertension blunts the development of salt-induced hypertension by causing glucosuria and natriuresis without changes in the RAAS or the expression or activity of the main Na+ channels and transporters.NEW & NOTEWORTHY The present study indicates that Na+-glucose cotransporter-2 (SGLT2) inhibition in a nondiabetic model of salt-sensitive hypertension blunts the development and magnitude of salt-induced hypertension. Chronic inhibition of SGLT2 increases glucose and Na+ excretion without secondary effects on the expression and function of other Na+ transporters and channels along the nephron and hormone levels in the renin-angiotensin-aldosterone system. These data provide novel insights into the effects of SGLT2 inhibitors and their potential use in hypertension.

Nephrotoxic Effects of Paraoxon in Three Rat Models of Acute Intoxication.

The delayed effects of acute intoxication by organophosphates (OPs) are poorly understood, and the various experimental animal models often do not take into account species characteristics. The principal biochemical feature of rodents is the presence of carboxylesterase in blood plasma, which is a target for OPs and can greatly distort their specific effects. The present study was designed to investigate the nephrotoxic effects of paraoxon (O,O-diethyl O-(4-nitrophenyl) phosphate, POX) using three models of acute poisoning in outbred Wistar rats. In the first model (M1, POX2x group), POX was administered twice at doses 110 µg/kg and 130 µg/kg subcutaneously, with an interval of 1 h. In the second model (M2, CBPOX group), 1 h prior to POX poisoning at a dose of 130 µg/kg subcutaneously, carboxylesterase activity was pre-inhibited by administration of specific inhibitor cresylbenzodioxaphosphorin oxide (CBDP, 3.3 mg/kg intraperitoneally). In the third model (M3), POX was administered subcutaneously just once at doses of LD16 (241 µg/kg), LD50 (250 µg/kg), and LD84 (259 µg/kg). Animal observation and sampling were performed 1, 3, and 7 days after the exposure. Endogenous creatinine clearance (ECC) decreased in 24 h in the POX2x group (p = 0.011). Glucosuria was observed in rats 24 h after exposure to POX in both M1 and M2 models. After 3 days, an increase in urinary excretion of chondroitin sulfate (CS, p = 0.024) and calbindin (p = 0.006) was observed in rats of the CBPOX group. Morphometric analysis revealed a number of differences most significant for rats in the CBPOX group. Furthermore, there was an increase in the area of the renal corpuscles (p = 0.0006), an increase in the diameter of the lumen of the proximal convoluted tubules (PCT, p = 0.0006), and narrowing of the diameter of the distal tubules (p = 0.001). After 7 days, the diameter of the PCT lumen was still increased in the nephrons of the CBPOX group (p = 0.0009). In the M3 model, histopathological and ultrastructural changes in the kidneys were revealed after the exposure to POX at doses of LD50 and LD84. Over a period from 24 h to 3 days, a significant (p = 0.018) expansion of Bowman's capsule was observed in the kidneys of rats of both the LD50 and LD84 groups. In the epithelium of the proximal tubules, stretching of the basal labyrinth, pycnotic nuclei, and desquamation of microvilli on the apical surface were revealed. In the epithelium of the distal tubules, partial swelling and destruction of mitochondria and pycnotic nuclei was observed, and nuclei were displaced towards the apical surface of cells. After 7 days of the exposure to POX, an increase in the thickness of the glomerular basement membrane (GBM) was observed in the LD50 and LD84 groups (p = 0.019 and 0.026, respectively). Moreover, signs of damage to tubular epithelial cells persisted with blockage of the tubule lumen by cellular detritus and local destruction of the surface of apical cells. Comparison of results from the three models demonstrates that the nephrotoxic effects of POX, evaluated at 1 and 3 days, appear regardless of prior inhibition of carboxylesterase activity.

Sex difference in kidney electrolyte transport III: Impact of low K intake on thiazide-sensitive cation excretion in male and female mice.

We compared the regulation of the NaCl cotransporter (NCC) in adaptation to a low-K (LK) diet in male and female mice. We measured hydrochlorothiazide (HCTZ)-induced changes in urine volume (UV), glomerular filtration rate (GFR), absolute (ENa, EK), and fractional (FENa, FEK) excretion in male and female mice on control-K (CK, 1% KCl) and LK (0.1% KCl) diets for 7 days. With CK, NCC-dependent ENa and FENa were larger in females than males as observed previously. However, with LK, HCTZ-induced ENa and FENa increased in males but not in females, abolishing the sex differences in NCC function as observed in CK group. Despite large diuretic and natriuretic responses to HCTZ, EK was only slightly increased in response to the drug when animals were on LK. This suggests that the K-secretory apparatus in the distal nephron is strongly suppressed under these conditions. We also examined LK-induced changes in Na transport protein expression by Western blotting. Under CK conditions females expressed more NCC protein, as previously reported. LK doubled both total (tNCC) and phosphorylated NCC (pNCC) abundance in males but had more modest effects in females. The larger effect in males abolished the sex-dependence of NCC expression, consistent with the measurements of function by renal clearance. LK intake did not change NHE3, NHE2, or NKCC2 expression, but reduced the amount of the cleaved (presumably active) form of γENaC. LK reduced plasma K to lower levels in females than males. These results indicated that males had a stronger NCC-mediated adaptation to LK intake than females.

p66Shc-mediated hydrogen peroxide production impairs nephrogenesis causing reduction of number of glomeruli.

AIMS: Adaptor protein p66Shc, encoded by Shc1 gene, contributes to the pathogenesis of oxidative stress-related diseases. p66Shc ability to promote oxidative stress-related diseases requires phosphorylation of serine 36 residue (Ser36) and depends on translocation of p66Shc to the mitochondria. We tested the hypothesis that abnormal p66Shc-mediated reactive oxygen species (ROS) production could be critically involved in nephrons development during nephrogenesis. MAIN METHODS: We have generated unique mutant rats (termed p66Shc-Del), which express endogenous p66Shc with a 9-amino acid deletion, and lack regulatory Ser36. H2O2 renal production was measured by enzymatic microelectrode biosensors. Nephron numbers in 3-5 weeks old p66Shc-Del rats were quantified using the acid maceration method. KEY FINDINGS: p66Shc-Del rats, as wild type salt sensitive rats, display increased mean arterial blood pressure following chronic exposure to a high salt diet. In contrast to wild type rats, p66Shc-Del rats display increased H2O2 renal production and are characterized by a reduction in renal function. The number of glomeruli is significantly reduced in adult p66Shc-Del rats. SIGNIFICANCE: Since low nephron number is an established risk factor for kidney disease and hypertension in humans and rodents, our data suggest that H2O2 renal production, caused by irregular signaling of p66Shc, could be critical in regulating nephrogenesis and that abnormal p66Shc signaling negatively impacts kidney development and renal function by increasing susceptibility to diabetic nephropathy and hypertension-induced nephropathy.

Association between diuretic administration before diagnosis and incidence of acute kidney injury in patients with minimal change disease: A single-center observational study.

ABSTRACT: We examined the association between diuretic administration before the diagnosis of minimal change disease and the incidence of acute kidney injury. Moreover, we examined whether the use of diuretics affected the time to complete remission in adults with such disease.The present study was a single-center, retrospective, observational cohort study. We included 107 patients with biopsy-proven minimal change disease who were treated at a tertiary referral center in Japan between January 1, 2000 and March 31, 2019. All biopsy specimens were examined by a board-certified renal pathologist. The patients were considered to have minimal change disease when the kidney biopsy specimen had no glomerular lesions or only mild focal mesangial prominence (not exceeding 3 or 4 cells per segment) by light microscopy and/or foot process effacement by electron microscopy. Logistic regression and Kaplan-Meier curve analyses were performed, comparing the data of patients who received diuretics or not.The median age was 47 (28-66) years, 52% of patients were women, and the median proteinuria dosage was 8.3 (5.3-11.2) g/d. When minimal change disease was diagnosed, 27% of patients were taking diuretics. Within 30 days after the diagnosis, acute kidney injury occurred in 27% of patients. On multivariable logistic regression analysis, the use of diuretics was significantly associated with a higher risk of acute kidney injury. The use of diuretics was also associated with a longer time to complete remission.Diuretic administration can be associated with an elevated acute kidney injury risk and longer remission time in adult patients with newly diagnosed minimal change disease.

Activation of autosomal recessive Pseudohypoaldosteronism1 ENaC with aldosterone.

The mineralocorticoid hormone aldosterone stimulates sodium reabsorption in the collecting ducts by increasing the activity of the epithelial sodium channel (ENaC). Being a rate-liming channel the loss of function mutations caused Pseudohypoaldosteronism 1 (PHA1). Despite elevated plasma aldosterone in PHA 1 patients the modulation of PHA 1 causing ENaC mutants with hormone has never been studied. After recording control ENaC current in PHA1 causing ENaC stop codon mutants we demonstrated the activation of aldosterone in the whole cell as well as single channel patch clamp assays. Single channel recoding experiments demonstrated that aldosterone can increase the open probability of all analyzed PHA 1 stop codon mutants and WT. Additionally, we demonstrated by western blot experiments that aldosterone can increase the expression of WT and PHA 1 stop codon mutants. Extensive whole cell patch clamp experiments demonstrated that C-terminal γ ENaC domain is necessary for aldosterone to activate whole cell current in HEK-293 cells. This novel finding of γ ENaC C-terminus dependent activation of whole cell current by aldosterone could alter our understanding of ENaC-mediated sodium reabsorption in the aldosterone-sensitive distal nephron (ASDN).

Inhibition of hepatocyte nuclear factor 1ß contributes to cisplatin nephrotoxicity via regulation of nf-κb pathway.

Cisplatin nephrotoxicity has been considered as serious side effect caused by cisplatin-based chemotherapy. Recent evidence indicates that renal tubular cell apoptosis and inflammation contribute to the progression of cisplatin-induced acute kidney injury (AKI). Hepatocyte nuclear factor 1ß (HNF1ß) has been reported to regulate the development of kidney cystogenesis, diabetic nephrotoxicity, etc However, the regulatory mechanism of HNF1ß in cisplatin nephrotoxicity is largely unknown. In the present study, we examined the effects of HNF1ß deficiency on the development of cisplatin-induced AKI in vitro and in vivo. HNF1ß down-regulation exacerbated cisplatin-induced RPTC apoptosis by indirectly inducing NF-κB p65 phosphorylation and nuclear translocation. HNF1ß knockdown C57BL/6 mice were constructed by injecting intravenously with HNF1ß-interfering shRNA and PEI. The HNF1ß scramble and knockdown mice were treated with 30 mg/kg cisplatin for 3 days to induce acute kidney injury. Cisplatin treatment caused increased caspase 3 cleavage and p65 phosphorylation, elevated serum urea nitrogen and creatinine, and obvious histological damage of kidney such as fractured tubules in control mice, which were enhanced in HNF1ß knockdown mice. These results suggest that HNF1ß may ameliorate cisplatin nephrotoxicity in vitro and in vivo, probably through regulating NF-κB signalling pathway.

Small molecule TCS21311 can replace BMP7 and facilitate cell proliferation in in vitro expansion culture of nephron progenitor cells.

Several groups have developed in vitro expansion cultures for mouse metanephric nephron progenitor cells (NPCs) using cocktails of small molecules and growth factors including BMP7. However, the detailed mechanisms by which BMP7 acts in the NPC expansion remain to be elucidated. Here, by performing chemical screening for BMP substitutes, we identified a small molecule, TCS21311, that can replace BMP7 and revealed a novel inhibitory role of BMP7 in JAK3-STAT3 signaling in NPC expansion culture. Further, we found that TCS21311 facilitates the proliferation of mouse embryonic NPCs and human induced pluripotent stem cell-derived NPCs when added to the expansion culture. These results will contribute to understanding the mechanisms of action of BMP7 in NPC proliferation in vitro and in vivo and to the stable supply of NPCs for regenerative therapy, disease modeling and drug discovery for kidney diseases.

Ouabain Protects Nephrogenesis in Rats Experiencing Intrauterine Growth Restriction and Partially Restores Renal Function in Adulthood.

Intrauterine growth restriction (IUGR) is, in general, accompanied by a reduction of the nephron number, which increases the risk of hypertension and renal dysfunction. Studies have revealed that ouabain can partially restore the number of nephrons during IUGR. However, there is limited information regarding the melioration of nephric structure and function. We used maternal malnutrition to induce an IUGR model in rats. Subsequently, we used a mini-pump to administer ouabain to IUGR rats during pregnancy. Male offspring were divided randomly into two groups. One group was fed a normal diet, whereas the other was fed an isocaloric 8% high-salt diet. Maternal malnutrition led to a reduction in the birth weight and number of nephrons in offspring. At the end of a 40-week follow-up period, offspring from the IUGR group had high blood pressure and abnormal excretion of urinary protein; these parameters were exacerbated in offspring fed a high-salt diet. However, ouabain administration during pregnancy could partially restore the number of nephrons in IUGR offspring, normalize blood pressure, and reduce urinary protein excretion, even when challenged with a high-salt diet. Pathology findings revealed that IUGR, particularly following feeding of a high-salt diet, damaged the ultrastructure of glomeruli, but these harmful effects were ameliorated in offspring treated with ouabain. Collectively, our data suggest that ouabain could rescue nephrogenesis in IUGR newborns and protect (at least in part) the structure and function of the kidney during adulthood even when encountering unfavorable environmental challenges in subsequent life.

NMR and LCMS analytical platforms exhibited the nephroprotective effect of Clinacanthus nutans in cisplatin-induced nephrotoxicity in the in vitro condition.

BACKGROUND: Clinacanthus nutans (C. nutans) Lind. locally known as Belalai Gajah or Sabah snake grass is a medicinal plant belonging to Acanthaceae family. In Asia, this plant is traditionally used for treating skin rashes, insects and snake bites, diabetes mellitus, fever and for diuretic effect. C. nutans has been reported to possess biological activities including anti-oxidant, anti-inflammation, anti-cancer, anti-diabetic and anti-viral activities. METHODS: Proton Nuclear Magnetic Resonance (1H NMR) and Liquid Chromatography Mass Spectroscopy (LCMS) coupled with multivariate data analysis were employed to characterize the metabolic variations of intracellular metabolites and the compositional changes of the corresponding culture media in rat renal proximal tubular cells (NRK-52E). RESULTS: NMR and LCMS analysis highlighted choline, creatine, phosphocholine, valine, acetic acid, phenylalanine, leucine, glutamic acid, threonine, uridine and proline as the main metabolites which differentiated the cisplatin-induced group of NRK-52E from control cells extract. The corresponding media exhibited lactic acid, glutamine, glutamic acid and glucose-1-phosphate as the varied metabolites. The altered pathways perturbed by cisplatin nephrotoxic on NRK-52E cells included changes in amino acid metabolism, lipid metabolism and glycolysis. CONCLUSION: The C. nutans aqueous extract (1000 µg/mL) exhibited the most potential nephroprotective effect against cisplatin toxicity on NRK-52E cell lines at 89% of viability. The protective effect could be seen through the changes of the metabolites such as choline, alanine and valine in the C. nutans pre-treated samples with those of the cisplatin-induced group.

Generation of Human Renal Vesicles in Mouse Organ Niche Using Nephron Progenitor Cell Replacement System.

Animal fetuses may be used for the regeneration of human organs. We have previously generated a transgenic mouse model that allows diphtheria toxin (DT)-induced ablation of Six2-positive nephron progenitor cells (NPCs). Elimination of existing native host NPCs enables their replacement with donor NPCs, which can generate neo-nephrons. However, this system cannot be applied to human NPCs, because DT induces apoptosis in human cells. Therefore, the present study presents a transgenic mouse model for the ablation of NPCs using tamoxifen, which does not affect human cells. Using this system, we successfully regenerate interspecies neo-nephrons, which exhibit urine-producing abilities, from transplanted rat NPCs in a mouse host. Transplantation of human induced pluripotent stem cell (iPSC)-derived NPCs results in differentiation into renal vesicles, which connect to the ureteric bud of the host. Thus, we demonstrate the possibility of the regeneration of human kidneys derived from human iPSC-derived NPCs via NPC replacement.

High Salt Intake-Increased (Pro)renin Receptor Expression Is Exaggerated in the Kidney of Dahl Salt-Sensitive Rats.

The (P)RR ([pro]renin receptor) was identified as a new component of the renin-angiotensin system. We previously reported that high salt (HS) intake increased the (P)RR expression in several nephron segments of Sprague-Dawley rats. Other studies reported HS intake increased the XO (xanthine oxidase) activity and an MR (mineralocorticoid receptor) antagonist inhibited HS intake-increased (P)RR expression in the kidneys of Dahl salt-sensitive (DS) rats. The present study examined the effects of HS intake on (P)RR expression in the kidney of DS rats. Male DS rats were fed a normal salt diet or an HS diet for 4 weeks. Some of the rats fed on the HS diet were treated with the XO inhibitor, febuxostat, and the MR antagonist, spironolactone. Immunoblot and immunohistochemical analyses showed that HS intake increased (P)RR expression in the renal cortex by 22.6-fold, the proximal tubules by 4.9-fold and the distal tubules, respectively. Both febuxostat and spironolactone inhibited HS intake-increased (P)RR expression in the renal cortex. Febuxostat inhibited HS intake-increased (P)RR expression in the proximal tubules, whereas spironolactone inhibited HS intake-increased (P)RR expression in the distal tubules. Additionally, deoxycorticosterone acetate increased (P)RR expression in the renal cortex and distal tubules but not in the proximal tubules of DS rats fed the normal salt diet. These results indicate that HS intake greatly increases (P)RR expression in the renal cortex of DS rats. The mechanisms of HS intake-increased (P)RR expression may work in an XO-dependent manner in the proximal tubules and an MR-dependent manner in the distal tubules.

Moderate prenatal ethanol exposure in the rat promotes kidney cell apoptosis, nephron deficits, and sex-specific kidney dysfunction in adult offspring.

Alcohol during pregnancy can impair fetal development and result in offspring with neurodevelopmental deficits. Less is known about how low to moderate alcohol exposure can affect other organs, such as the kidney. Here, the effects of moderate ethanol exposure throughout pregnancy on kidney development were examined using a rat model. Rats were fed a liquid diet containing 6% ethanol (vol/vol) or control (0% ethanol) throughout pregnancy. Kidneys were collected at embryonic day (E) 20 or postnatal day (PN) 30 and total glomerular (nephron) number determined using unbiased stereology. Kidney function was examined in offspring at 8 and 19 months. At E20, fetuses exposed to ethanol had fewer nephrons with increased apoptosis. Alcohol exposure caused kidney dysregulation of pro- (Bax) and anti- (Bcl-2) apoptotic factors, and reduced expression of the cell proliferation marker, Ki67. Prenatal alcohol decreased expression of Gdnf and Tgfb1, important regulators of branching morphogenesis, in male fetuses. At PN30, kidney volume and nephron number were lower in offspring exposed to prenatal alcohol. Urine flow and osmolality were normal in offspring exposed to alcohol however sodium excretion tended to be lower in females prenatally exposed to alcohol. Findings suggest exposure to moderate levels of alcohol during pregnancy results in impaired kidney development and leads to a permanent nephron deficit. Although the impact on adult kidney function was relatively minor, these data highlight that even at moderate levels, alcohol consumption during pregnancy can have deleterious long-term outcomes and should be avoided.

Multivariate patterning of human pluripotent cells under perfusion reveals critical roles of induced paracrine factors in kidney organoid development.

Creating complex multicellular kidney organoids from pluripotent stem cells shows great promise. Further improvements in differentiation outcomes, patterning, and maturation of specific cell types are, however, intrinsically limited by standard tissue culture approaches. We describe a novel full factorial microbioreactor array-based methodology to achieve rapid interrogation and optimization of this complex multicellular differentiation process in a facile manner. We successfully recapitulate early kidney tissue patterning events, exploring more than 1000 unique conditions in an unbiased and quantitative manner, and define new media combinations that achieve near-pure renal cell type specification. Single-cell resolution identification of distinct renal cell types within multilayered kidney organoids, coupled with multivariate analysis, defined the definitive roles of Wnt, fibroblast growth factor, and bone morphogenetic protein signaling in their specification, exposed retinoic acid as a minimal effector of nephron patterning, and highlighted critical contributions of induced paracrine factors on cell specification and patterning.

Aldosterone controls primary cilium length and cell size in renal collecting duct principal cells.

Primary cilia are nonmotile sensory organelles found on the surface of almost all kidney tubule epithelial cells. Being exposed to the tubular lumen, primary cilia are thought to be chemo- and mechanosensors of luminal composition and flux, respectively. We hypothesized that, Na+ transport and primary cilia exist in a sensory functional connection in mature renal tubule epithelial cells. Our results demonstrate that primary cilium length is reduced in mineralocorticoid receptor (MR) knockout (KO) mice in a cell autonomous manner along the aldosterone-sensitive distal nephron (ADSN) compared with wild type (as µm ± SEM; 3.1 ± 0.2 vs 4.0 ± 0.1). In mouse cortical collecting duct (mCCD)cl1 cells, which are a model of collecting duct (CD) principal cells, changes in Na+ transport intensity were found to mediate primary cilium length in response to aldosterone (as µm ± SEM: control: 2.7 ± 0.9 vs aldosterone treated: 3.8 ± 0.8). Cilium length was positively correlated with the availability of IFT88, a major intraflagellar anterograde transport complex B component, which is stabilized in response to exposure to aldosterone treatment. This suggests that the abundance of IFT88 is a regulated, rate limiting factor in the elongation of primary cilia. As previously observed in vivo, aldosterone treatment increased cell volume of cultured CD principal cells. Knockdown of IFT88 prevents ciliogenesis and inhibits the adaptive increase in cell size that was observed in response to aldosterone treatment. In conclusion, our results reveal a functional connection between Na+ transport, primary cilia, and cell size, which may play a key role in the morphological and functional adaptation of the CD to sustained changes in active Na+ reabsorption due to variations in aldosterone secretion.

Turning Foes to Friends: Knocking Down Diabetes Associated SGLT2 Transporters and Sustaining Life.

BACKGROUND: The discovery of Sodium-Glucose co-transporter-2 (SGLT2) inhibitors had rewritten the treatment of diabetes mellitus with an impressive fall in the incidence of death and associated complications. INTRODUCTION: The SGLT2 inhibitors by inhibiting the SGLT2 in the proximal nephron, helps in reducing the reabsorption of approximately 90% of the filtered glucose and increased urinary glucose excretion (UGE). METHODS: The literature related to SGLT2 inhibitors has been thoroughly explored from various available public domains and reviewed extensively for this article. Detailed and updated information related to SGLT2 inhibitors with a major focus on the recently approved Ertuglifolzin is structured in this review. RESULT: The present review is an effort to understand the management of diabetes mellitus over the past few decades with a special focus on the role of SGLT2 receptor in the causes of therapeutic and preventive strategies for diabetes mellitus. Pragmatic placement of the currently available Canagliflozin, Dapagliflozin, and Empagliflozin as oral antidiabetic agents has been done. Well accommodated stereochemistry and a high docking score of Ertugliflozin in ligand-receptor simulation studies attribute to its high potency. CONCLUSION: This review highlights the unique mechanism of SGLT2 Inhibitors coupled with pleiotropic benefits on weight and blood pressure, which make it an attractive choice of therapy to diabetic patients, not controlled by other medications.

Angiotensin II-induced superoxide and decreased glutathione in proximal tubules: effect of dietary fructose.

Angiotensin II exacerbates oxidative stress in part by increasing superoxide (O2-) production by many renal tissues. However, whether it does so in proximal tubules and the source of O2- in this segment are unknown. Dietary fructose enhances the stimulatory effect of angiotensin II on proximal tubule Na+ reabsorption, but whether this is true for oxidative stress is unknown. We hypothesized that angiotensin II causes proximal nephron oxidative stress in part by stimulating NADPH oxidase (NOX)4-dependent O2- production and decreasing the amount of the antioxidant glutathione, and this is exacerbated by dietary fructose. We measured basal and angiotensin II-stimulated O2- production with and without inhibitors, NOX1 and NOX4 expression, and total and reduced glutathione (GSH) in proximal tubules from rats drinking either tap water (control) or 20% fructose. Angiotensin II (10 nM) increased O2- production by 113 ± 42 relative light units·mg protein-1·s-1 in controls and 401 ± 74 relative light units·mg protein-1·s-1 with 20% fructose (n = 11 for each group, P < 0.05 vs. control). Apocynin and the Nox1/4 inhibitor GKT136901 prevented angiotensin II-induced increases in both groups. NOX4 expression was not different between groups. NOX1 expression was undetectable. Angiotensin II decreased GSH by 1.8 ± 0.8 nmol/mg protein in controls and by 4.2 ± 0.9 nmol/mg protein with 20% fructose (n = 18 for each group, P < 0.047 vs. control). We conclude that 1) angiotensin II causes oxidative stress in proximal tubules by increasing O2- production by NOX4 and decreasing GSH and 2) dietary fructose enhances the ability of angiotensin II to stimulate O2- and diminish GSH, thereby exacerbating oxidative stress in this segment.

Resveratrol reverts Streptozotocin-induced diabetic nephropathy.

Diabetes causes diabetic nephropathy (DN) which is associated with increased morbidity and mortality in diabetic patients. We tested whether Resveratrol (Res) reverses the systemic effect of Streptozotocin (STZ) induced diabetes and DN. Res treatment opposed the effect of STZ on kidney weight, 24 h urinary albumin excretion, blood urea nitrogen (BUN) and serum creatinine (Scr). Res also decreased DN induced mTOR/ULK1-mediated autophagy and apoptosis and significantly reduced STZ mediated lipid deposition in nephrons, likely by decreasing the levels of lipogenic related proteins (SREBP-1c, ACS) and increased lipidolysis related proteins (PPARα, CPT-1). Together, these findings show the potential of Res in prevention of diabetic nephropathy.

Periconceptional ethanol exposure induces a sex specific diuresis and increase in AQP2 and AVPR2 in the kidneys of aged rat offspring.

Maternal alcohol consumption can impair renal development and program kidney dysfunction in offspring. Given that most women who drink alcohol cease consumption upon pregnancy recognition, we aimed to investigate the effect of alcohol around the time of conception (PC:EtOH) on offspring renal development and function. Rats received a liquid diet ±12.5% v/v ethanol from 4 days before to 4 days after mating. At postnatal day 30, nephron number was assessed. Urine flow and electrolyte (Na, K, Cl) excretion was measured at 6 and 19 months and blood pressure at 12 months. At 19 months, kidneys were collected for gene and protein analysis and assessment of collecting duct length. At postnatal day 30, PC:EtOH offspring had fewer nephrons. At 6 months, PC:EtOH exposure did not alter urine flow nor affect blood pressure at 12 months. At 19 months, female but not male offspring exposed to PC:EtOH drank more water and had a higher urine flow despite no differences in plasma arginine vasopressin (AVP) concentrations. Aqp2 mRNA and Avpr2 mRNA and protein expression was increased in kidneys from female PC:EtOH offspring but collecting duct lengths were similar. Immunofluorescent staining revealed diffuse cytoplasmic distribution of AQP2 protein in kidneys from PC:EtOH females, compared with controls with apical AQP2 localization. PC:EtOH resulted in a low nephron endowment and in female offspring, associated with age-related diuresis. Changes in expression and cellular localization of AQP2 likely underpin this disturbance in water homeostasis and highlight the need for alcohol to be avoided in early pregnancy.