Increase In Glomerular Volume Research Articles

PS-B12-10: CLASSIC CARDIOVASCULAR PROTECTIVE SIGNALING IN ANGIOTENSIN II-INDUCED NOVEL PREECLAMPSIA RAT MODEL

Angiotensin II (Ang II)-induces vasoconstriction, in vivo perfusion has been shown to induce preeclampsia (PE) in pregnant rats. In this study, we aimed to examine the protein and mRNA expressions of endothelial and neuronal NOS (eNOS, nNOS) as well as angiotensin II type 2 receptor (AT2R) in normal pregnant and Ang II-induced PE rats. Pregnant (8 weeks) and non-pregnant SD rats (8 weeks, GD-8) were infused with Ang II via an osmotic minipump (1 ug/kg/min), and the rats (GD-21) were sacrificed 13 days later. Pregnant and non-pregnant rats without Ang II were taken as sham controls. The fetal weight, crown-rump length and placental weight of PE rats were significantly lower compared to those without Ang II infusion. Immunohistochemistry results showed an approximately 30% increase in glomerular volume, suggesting morphological changes in the kidney and Ang II infusion exhibits a PE phenotype. Ang II infusion did not affect AT2R, AT1R and nNOS protein or mRNA expression in the uterus of non-pregnant or pregnant rats. However, eNOS mRNA expression was reduced in PE rats (p < 0.0001) although protein expression was not affected by Ang II infusion. However, in the placenta, AT1R and AT2R protein expression were not different in PE, but AT2R mRNA was decreased (p < 0.0001). eNOS protein was only expressed in fetal vascular endothelial cells, and eNOS protein expression was higher in PE rats (P = 0.001) but eNOS mRNA was decreased (p = 0.0096). Notably, strong nNOS expression was observed in placental trophoblast cell groups of sham and PE rats, and both mRNA and protein expression of nNOS was decreased in placental lysates of Ang II rats (respectively p = 0.0287 and p < 0.0001). These results demonstrate that we have recapitulated the PE model of Ang II infusion in rats. The expression of nNOS was reduced, and the localization of nNOS in the trophoblast suggested a new functional remodeling in the fetal vasculature. In the placenta, decreased expression of AT2R and nNOS may be a novel mechanism of impaired fetal development.

CLASSIC CARDIOVASCULAR PROTECTIVE SIGNALING IN ANGIOTENSIN II-INDUCED NOVEL PREECLAMPSIA RAT MODEL

Objective: Angiotensin II (Ang II)-induces vasoconstriction, in vivo perfusion has been shown to induce preeclampsia (PE) in pregnant rats. In this study, we aimed to examine the protein and mRNA expressions of endothelial and neuronal NOS (eNOS, nNOS) as well as angiotensin II type 2 receptor (AT2R) in normal pregnant and Ang II-induced PE rats. Design and method: Pregnant (8 weeks) and non-pregnant SD rats (8 weeks, GD-8) were infused with Ang II via an osmotic minipump (1 ug/kg/min), and the rats (GD-21) were sacrificed 13 days later. Pregnant and non-pregnant rats without Ang II were taken as sham controls. The fetal weight, crown-rump length and placental weight of PE rats were significantly lower compared to those without Ang II infusion. Immunohistochemistry results showed an approximately 30% increase in glomerular volume, suggesting morphological changes in the kidney and Ang II infusion exhibits a PE phenotype. Results: Ang II infusion did not affect AT2R, AT1R and nNOS protein or mRNA expression in the uterus of non-pregnant or pregnant rats. However, eNOS mRNA expression was reduced in PE rats (p < 0.0001) although protein expression was not affected by Ang II infusion. However, in the placenta, AT1R and AT2R protein expression were not different in PE, but AT2R mRNA was decreased (p < 0.0001). eNOS protein was only expressed in fetal vascular endothelial cells, and eNOS protein expression was higher in PE rats (P = 0.001) but eNOS mRNA was decreased (p = 0.0096). Notably, strong nNOS expression was observed in placental trophoblast cell groups of sham and PE rats, and both mRNA and protein expression of nNOS was decreased in placental lysates of Ang II rats (respectively p = 0.0287 and p < 0.0001). Conclusions: These results demonstrate that we have recapitulated the PE model of Ang II infusion in rats. The expression of nNOS was reduced, and the localization of nNOS in the trophoblast suggested a new functional remodeling in the fetal vasculature. In the placenta, decreased expression of AT2R and nNOS may be a novel mechanism of impaired fetal development.

Critical timing of ACEi initiation prevents compensatory glomerular hypertrophy in the remaining single kidney

Increasing evidence suggests that single in kidney states (e.g., kidney transplantation and living donation) progressive glomerulosclerosis limits kidney lifespan. Modeling shows that post-nephrectomy compensatory glomerular volume (GV) increase drives podocyte depletion and hypertrophic stress resulting in proteinuria and glomerulosclerosis, implying that GV increase could serve as a therapeutic target to prevent progression. In this report we examine how Angiotensin Converting Enzyme inhibition (ACEi), started before uninephrectomy can reduce compensatory GV increase in wild-type Fischer344 rats. An unbiased computer-assisted method was used for morphometric analysis. Urine Insulin-like growth factor-1 (IGF-1), the major diver of body and kidney growth, was used as a readout. In long-term (40-week) studies of uni-nephrectomized versus sham-nephrectomized rats a 2.2-fold increase in GV was associated with reduced podocyte density, increased proteinuria and glomerulosclerosis. Compensatory GV increase was largely prevented by ACEi started a week before but not after uni-nephrectomy with no measurable impact on long-term eGFR. Similarly, in short-term (14-day) studies, ACEi started a week before uni-nephrectomy reduced both GV increase and urine IGF-1 excretion. Thus, timing of ACEi in relation to uni-nephrectomy had significant impact on post-nephrectomy “compensatory” glomerular growth and outcomes that could potentially be used to improve kidney transplantation and live kidney donation outcomes.

Human kidney graft survival correlates with structural parameters in baseline biopsies: a quantitative observational cohort study with more than 14 years' follow-up.

This prospective cohort study evaluates associations between structural and ultrastructural parameters in baseline biopsies from human kidney transplants and long-term graft survival after more than 14 years' follow-up. Baseline kidney graft biopsies were obtained prospectively from 54 consecutive patients receiving a kidney transplant at a single institution. Quantitative measurements were performed on the baseline biopsies by computer-assisted light microscopy and electron microscopy. Stereology-based techniques estimated the fraction of interstitial tissue, the volume of glomeruli, mesangial fraction, and basement membrane thickness of glomerular capillaries. The fraction of occluded glomeruli and scores according to the Banff classification were achieved. Kidney graft survival was analyzed by Kaplan-Meier estimates and Cox regression. Association to long-term kidney function was also analyzed. The long-term surviving kidney transplants were characterized at implantation by less arteriolar hyaline thickening (P < 0.001) and less interstitial fibrosis (P = 0.001), as well as a lower fraction of occluded glomeruli (P = 0.004) and lower glomerular volume (P = 0.03). At the latest follow-up, eGFR was decreased by 12 ml/min/1.73 m2 per unit increase in the score for arteriolar hyalinosis at implantation (P = 0.02), and eGFR was decreased by 19 ml/min/1.73 m2 per 106 μm3 increase in glomerular volume at baseline (P = 0.03). The unbiased Cavalieri estimate of glomerular volume and the ultrastructural parameters are the first to be evaluated in a cohort study with prospective follow-up for more than 14 years. The study shows that baseline biopsies from human kidney grafts contain extraordinary long-term prognostic information, and it highlights the importance of these intrinsic graft factors.

Establishment of a rat model of nonalcoholic steatohepatitis and histopathological changes of the pancreas and the kidney

Objective To establish a rat model of nonalcoholic steatohepatitis,and to investigate the histopathological changes of the extrahepatic organs of the pancreas and the kidney. Methods A total of 20 Sprague-Dawley rats were selected,among which 6 were randomly selected as the observation group(group B). The remaining 14 rats were paired into seven groups according to body weight,then a random number table was used to select 1 rat from each group and assign them into the experimental group(group C),and the remaining 7 rats were assigned to the control group(group A). The rats in groups B and C were given high-fat diet,while those in group A were given a normal diet. In group B,two rats each were killed at weeks 4,8,and 12 of the experiment,liver tissue was extracted for HE staining,and liver pathological sections were observed under a microscope to see whether steatohepatitis was achieved. The model was successfully established at the end of week 12. All rats in groups A and C were sacrificed,and the serological markers alanine aminotransferase(ALT),aspartate aminotransferase(AST),gamma-glutamyl transpeptidase(GGT),triglyceride(TG),total cholesterol(TC),low-density lipoprotein(LDL),glucose(GLU),insulin(INS),and homeostasis model assessment of insulin resistance(HOMA-IR) were measured. HE staining was performed for liver tissue and pancreatic tissue to observe the changes in pancreatic acini and pancreatic islets. PAS staining was performed for kidney tissue,and immunohistochemical desmin-staining was performed to observe the expression of desmin in glomerular podocytes. The t-test was used for comparison of continuous data between two groups. Results Compared with group A,group C had significantly higher pathological score and serum levels of ALT,GGT,LDL,TG,TC,GLU,INS,and HOMA-IR(t = 4. 67,2. 83,2. 34,4. 58,4. 78,3. 00,2. 97,3. 80 and 4. 10,all P < 0. 05). Liver pathological changes were observed in the high-fat group from week 4 to week 12,i. e.,the lobular structure was gradually destroyed,the small fat vacuoles in the cytoplasm of the hepatocytes gradually developed into large fat vacuoles,and inflammatory cell infiltration gradually appeared in the portal area. Pancreatic pathological changes were observed in the high-fat group at the end of week 12,i. e.,apoptosis and atrophy of pancreatic acinar cells were observed,and no significant abnormalities were observed in pancreatic islet cells. Renal pathological changes were observed in the high-fat group at the end of week 12,i. e.,therewere significant increases in the substances with positive PAS staining results,the glomerular volume,and the thickness of the glomerular capillary basement membrane,with disordered arrangement of capillary loops,hyperplasia of the mesangial area,swelling of renal tubular epithelial cells,and stenosis of some lumens. Immunohistochemical staining showed an increase in the expression of desmin in glomerular podocytes in the high-fat group. Conclusion A rat model of nonalcoholic steatohepatitis is successfully established by high-fat diet.Nonalcoholic steatohepatitis in rats may lead to apoptosis and atrophy of pancreatic acinar cells,increase in glomerular volume,thickening of the capillary basement membrane,mesangial hyperplasia,and podocyte injury.

Deletion of pro-angiogenic factor vasohibin-2 ameliorates glomerular alterations in a mouse diabetic nephropathy model

Angiogenesis has been implicated in glomerular alterations in the early stage of diabetic nephropathy. We previously reported the renoprotective effects of vasohibin-1 (VASH1), which is a novel angiogenesis inhibitor derived from endothelial cells, on diabetic nephropathy progression. Vasohibin-2 (VASH2) was originally identified as a VASH1 homolog and possesses pro-angiogenic activity in contrast to VASH1. In addition, VASH2 was recently shown to promote epithelial-to-mesenchymal transition via enhanced transforming growth factor (TGF)-β signaling in cancer cells. Herein, we investigated the pathogenic roles of VASH2 in diabetic nephropathy using VAHS2-deficient mice. The type 1 diabetes model was induced by intraperitoneal injections of streptozotocin in VASH2 homozygous knockout (VASH2LacZ/LacZ) or wild-type mice. These mice were euthanized 16 weeks after inducing hyperglycemia. Increased urine albumin excretion and creatinine clearance observed in diabetic wild-type mice were significantly prevented in diabetic VASH2-deficient mice. Accordingly, diabetes-induced increase in glomerular volume and reduction in glomerular slit-diaphragm density were significantly improved in VASH2 knockout mice. Increased glomerular endothelial area was also suppressed in VASH2-deficient mice, in association with inhibition of enhanced vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2), but not VEGF level. Furthermore, glomerular accumulation of mesangial matrix, including type IV collagen, and increased expression of TGF-β were improved in diabetic VASH2 knockout mice compared with diabetic wild-type mice. Based on the immunofluorescence findings, endogenous VASH2 localization in glomeruli was consistent with mesangial cells. Human mesangial cells (HMCs) were cultured under high glucose condition in in vitro experiments. Transfection of VASH2 small interfering RNA (siRNA) into the HMCs resulted in the suppression of type IV collagen production induced by high glucose compared with control siRNA. These results indicate that VASH2 may be involved in diabetes-induced glomerular alterations, particularly impaired filtration barrier and mesangial expansion. Therefore, VASH2 is likely to represent a promising therapeutic target for diabetic nephropathy.

Effect of Euterpe oleracea Mart. Seeds Extract on Chronic Ischemic Renal Injury in Renovascular Hypertensive Rats.

Previously, we have demonstrated that the seeds of Euterpe oleracia Mart. (açaí) are rich in polyphenols with antihypertensive and antioxidant properties. This study evaluated the renal protective effects of the hydroalcoholic extract obtained from the seeds of açaí (ASE) fruits in two-kidney, one-clip (2K1C) renovascular hypertension. Young male Wistar rats were used to obtain 2K1C and sham groups. Animals received ASE (200 mg/(kg·day) in drinking water) or vehicle for 40 days. We evaluated serum and urinary parameters, renal structural changes, and oxidative status. The increase in systolic blood pressure of the 2K1C group was accompanied by a decrease in left kidney volume and number of glomeruli, as well as an increase in glomerular volume and collagen deposition. ASE prevented the alterations of these parameters, except the reduced kidney volume. Serum levels of urea and creatinine and urinary protein excretion were increased in the 2K1C group and treatment with ASE improved all these functional parameters. The increased oxidative damage in the 2K1C group, assessed by lipid and protein oxidation, was prevented by ASE. The nitrite content and both expression and activity of antioxidant enzymes (superoxide dismutase-1, catalase, and glutathione peroxidase) were lower in the 2K1C group and restored by ASE. ASE substantially reduced renal injury and prevented renal dysfunction in 2K1C rats probably through its antihypertensive and antioxidant effects, providing a natural resource for treatment and prevention of renovascular hypertension-related abnormalities.

Neonatal high protein intake enhances neonatal growth without significant adverse renal effects in spontaneous IUGR piglets.

In humans, early high protein (HP) intake has been recommended to prevent postnatal growth restriction and complications of intrauterine growth restriction (IUGR). However, the impact of such a strategy on the kidneys remains unknown, while significant renal hypertrophy, proteinuria, and glomerular sclerosis have been demonstrated in few experimental studies. The objective of this study was to evaluate the effects of a neonatal HP formula on renal structure in IUGR piglets. Spontaneous IUGR piglets were randomly allocated to normal protein (NP, n = 10) formula or to HP formula (+50% protein content, n = 10) up to day 28 after birth. Body weight, body composition, renal functions, and structure were assessed at the end of the neonatal period. While birth weights were similar, 28‐day‐old HP piglets were 18% heavier than NP piglets (P < 0.01). Carcass protein content was 22% higher in HP than in NP offspring (P < 0.01). Despite a HP intake, kidney weight and glomerular fibrosis were unaltered in HP piglets. Only a 20% increase in glomerular volume was noted in HP piglets (P < 0.05) and restricted to the inner cortical area nephrons (P = 0.03). Plasma urea/creatinine ratio and proteinuria were unchanged in HP piglets. In conclusion, neonatal HP feeding in IUGR piglets significantly enhanced neonatal growth and tissue protein deposition but mildly affected glomerular volume. It can be speculated that a sustained tissue protein anabolism in response to HP intake have limited single nephron glomerular hyperfiltration.

Mechanism of Notch Pathway Activation and Its Role in the Regulation of Olfactory Plasticity in Drosophila melanogaster.

The neural plasticity of sensory systems is being increasingly recognized as playing a role in learning and memory. We have previously shown that Notch, part of an evolutionarily conserved intercellular signaling pathway, is required in adult Drosophila melanogaster olfactory receptor neurons (ORNs) for the structural and functional plasticity of olfactory glomeruli that is induced by chronic odor exposure. In this paper we address how long-term exposure to odor activates Notch and how Notch in conjunction with chronic odor mediates olfactory plasticity. We show that upon chronic odor exposure a non-canonical Notch pathway mediates an increase in the volume of glomeruli by a mechanism that is autonomous to ORNs. In addition to activating a pathway that is autonomous to ORNs, chronic odor exposure also activates the Notch ligand Delta in second order projection neurons (PNs), but this does not appear to require acetylcholine receptor activation in PNs. Delta on PNs then feeds back to activate canonical Notch signaling in ORNs, which restricts the extent of the odor induced increase in glomerular volume. Surprisingly, even though the pathway that mediates the increase in glomerular volume is autonomous to ORNs, nonproductive transsynaptic Delta/Notch interactions that do not activate the canonical pathway can block the increase in volume. In conjunction with chronic odor, the canonical Notch pathway also enhances cholinergic activation of PNs. We present evidence suggesting that this is due to increased acetylcholine release from ORNs. In regulating physiological plasticity, Notch functions solely by the canonical pathway, suggesting that there is no direct connection between morphological and physiological plasticity.

Abstract MP11: Striatin Heterozygous Knockout Mice Have Increased Aldosterone Sensitivity

Background: We recently demonstrated that mice lacking one copy of the striatin gene (Strn+/-) have salt sensitivity of blood pressure (BP) as compared with WT mice. To determine whether Strn+/- mice have increased sensitivity to aldosterone (ALDO), we assessed the effect on blood pressure of an ALDO infusion in WT and Strn+/- mice fed a liberal sodium diet. Methods: In this study we used 12 week old WT and Strn+/- littermate male mice. For each genotype, mice were placed on HS diet and randomized to either: 1) placebo 2) ALDO (200 μg/Kg/day) or 3) ALDO plus 100 mg/kg/day eplerenone. BP was measured by tail cuff plethysmography at baseline and after treatment. After 21 days of treatment, animals were placed in metabolic cages for 24 hours. Finally, animals were sacrificed and organs excised. Primary endpoints were BP, renal immunohistochemistry, protein analysis by western blot and mRNA expression by RT-PCR. Results: BP increased significantly in Strn+/- mice treated with ALDO (ΔBP: 12 ± 4 mmHg, p=0.03) but not placebo (ΔBP 6± 6 mmHg); the BP effect of ALDO was blunted by eplerenone (Δ 6 ± 3 mmHg). In contrast, none of the treatments had a significant effect on BP in WT mice. Kidney weight was significantly increased after 3 weeks of ALDO treatment in both WT and Strn+/- mice and this increase in kidney weight was prevented by treatment with eplerenone, with no difference between genotypes. WT mice had an increase in glomerular volume (GV) in HS/ALDO treated that was blunted by eplerenone. Interestingly, Strn+/- mice had increased GV across all 3 treatment groups compared with WT mice. pAkt/Akt ratios were reduced in Strn+/- mice versus WT mice across all treatments. Classic genomic MR targets (ENaC and SGK1) and non-genomic targets (pAkt/Akt) were significantly modulated in kidney tissue of Strn+/- mice compared to WT mice with chronic ALDO. Conclusion: Strn+/- mice have an increased sensitivity to infused ALDO (increased BP response and increased rise in renal ENaC and SGK1 protein) as compared to WT mice. Since loss of striatin directly reduces nongenomic not genomic action of ALDO, this study demonstrates for the first time that modifying the nongenomic pathway may under chronic, in vivo conditions led to increased sensitivity to the genomic actions of ALDO.

Αlpha-Tocopherol Supplementation Diminishes the Renal Damage Caused by Experimental Diabetes

Background: Previous studies have shown alpha- tocopherol favorable effects on biochemical markers of kidney function and tissue damage in experimental models of diabetes. However, few reports highlight its effect in organ morphology and even less its impact during pregnancy. The main goal of this study was to evaluate the effect of alpha- tocopherol supplementation on the renal tissue morphology of diabetic pregnant rats. Methods: Diabetes was induced in female Wistar rats after intraperitoneal administration of streptozotocin. Healthy rats without any preparation were used as control subjects. Diabetic and control rats were grouped by receiving oral alpha-tocopherol 150 mg/kg/day or the vehicle during pregnancy. Euthanasia was practiced by bleeding under anesthesia at 20 days of gestation. Metabolic markers in plasma were analyzed and the kidney cortex morphology was studied by optical and electron microscopy. Statistic studies were performed using Kruskal Wallis, U Mann-Withney, Dunn and Fisher tests; significant differences were considered with p<0.05. Results: Diabetic rats presented a lower weight gain than the control group, hyperglycemia, hypercholesterolemia and morphological alterations on renal cortex, with increase in glomerular volume and 70% of tubular damage. A lower incidence of kidney lesions was observed in diabetic rats that received alpha- tocopherol, with similar glomerular volumes to the control and improved of tubular cells with only 36% of damage. Conclusions: The administration of alpha- tocopherol to diabetic rats during gestation showed a protective effect on the morphology kidney. This result would be related to the antioxidant action of alpha- tocopherol, but further studies are needed to confirm this.

Early chronic low-level lead exposure produces glomerular hypertrophy in young C57BL/6J mice

Early chronic lead exposure continues to pose serious health risks for children, particularly those living in lower socioeconomic environments. This study examined effects on developing glomeruli in young C57BL/6J mice exposed to low (30ppm), higher (330ppm) or no lead via dams’ drinking water from birth to sacrifice on post-natal day 28. Low-level lead exposed mice [BLL mean (SD); 3.19 (0.70)μg/dL] had an increase in glomerular volume but no change in podocyte number compared to control mice [0.03 (0.01)μg/dL]. Higher-level lead exposed mice [14.68 (2.74)μg/dL] had no change in either glomerular volume or podocyte number. The increase in glomerular volume was explained by increases in glomerular capillary and mesangial volumes with no change in podocyte volume. Early chronic lead exposure yielding very low blood lead levels alters glomerular development in pre-adolescent animals.

Fluorescent Microangiography Is a Novel and Widely Applicable Technique for Delineating the Renal Microvasculature

Rarefaction of the renal microvasculature correlates with declining kidney function. However, current technologies commonly used for its evaluation are limited by their reliance on endothelial cell antigen expression and assessment in two dimensions. We set out to establish a widely applicable and unbiased optical sectioning method to enable three dimensional imaging and reconstruction of the renal microvessels based on their luminal filling. The kidneys of subtotally nephrectomized (SNx) rats and their sham-operated counterparts were subjected to either routine two-dimensional immunohistochemistry or the novel technique of fluorescent microangiography (FMA). The latter was achieved by perfusion of the kidney with an agarose suspension of fluorescent polystyrene microspheres followed by optical sectioning of 200 µm thick cross-sections using a confocal microscope. The fluorescent microangiography method enabled the three-dimensional reconstruction of virtual microvascular casts and confirmed a reduction in both glomerular and peritubular capillary density in the kidneys of SNx rats, despite an overall increase in glomerular volume. FMA is an uncomplicated technique for evaluating the renal microvasculature that circumvents many of the limitations imposed by conventional analysis of two-dimensional tissue sections.

Role of 12-lipoxygenase in decreasing P-cadherin and increasing angiotensin II type 1 receptor expression according to glomerular size in type 2 diabetic rats

12-lipoxygenase (12-LO) was implicated in the development of diabetic nephropathy (DN), in which the proteinuria was thought to be associated with a decreased expression of glomerular P-cadherin. Therefore, we investigated the role of 12-LO in the glomerular P-cadherin expression in type 2 diabetic rats according to the glomerular sizes. Rats fed with high-fat diet for 6 wk were treated with low-dose streptozotocin. Once diabetes onset, diabetic rats were treated with 12-LO inhibitor cinnamyl-3,4-dihydroxy-cyanocinnamate (CDC) for 8 wk. Then glomeruli were isolated from diabetic and control rats with a sieving method. RT-PCR, Western blotting, and immunofluorescent staining were used for mRNA and protein expressions of P-cadherin and angiotensin II (Ang II) type 1 receptor (AT1). We found that CDC did not affect the glucose levels but completely attenuated diabetic increases in glomerular volume and proteinuria. Diabetes significantly decreased the P-cadherin mRNA and protein expressions and increased the AT1 mRNA and protein expressions in the glomeruli. These changes were significantly prevented by CDC and recaptured by direct infusion of 12-LO product [12(S)-HETE] to normal rats for 7 days. The decreased P-cadherin expression was similar between large and small glomeruli, but the increased AT1 expression was significantly higher in the large than in the small glomeruli from diabetic and 12(S)-HETE-treated rats. Direct infusion of normal rats with Ang II for 14 days also significantly decreased the glomerular P-cadherin expression. These results suggest that diabetic proteinuria is mediated by the activation of 12-LO pathway that is partially attributed to the decreased glomerular P-cadherin expression.

Renal phenotype in heterozygous Lmx1b knockout mice (Lmx1b +/−) after unilateral nephrectomy

The nail-patella syndrome (NPS) is a rare autosomal-dominant disorder which is caused by loss-of-function mutations in the transcription factor LMX1B. NPS is characterized by dysplastic nails, absent or hypoplastic patellae, minor skeletal abnormalities and nephropathy (in 20-40% of the cases), which is the most severe aspect of the disorder. The current data suggest that genetic modifiers in the outbred human genetic background are responsible for this variable phenotype. Preliminary work on the function of Lmx1b in the kidney has been performed using Lmx1b knockout mice (Lmx1b (-/-)). Although Lmx1b (-/-) mice die within 24 h after birth, they exhibit the characteristic NPS features including the renal abnormalities. But in contrast to the situation in human, no phenotype could so far be detected in heterozygous Lmx1b (+/-) mice. This indicates that our understanding of the pathomechanism underlying the nephropathy is still very limited. In an attempt to further evaluate these mechanisms, we tried to induce a renal phenotype in Lmx1b (+/-) mice, and thus model the human (NPS) situation. We applied unilateral nephrectomy as a model to induce nephron loss and detected a significant (p = 0.02) reduction in compensatory renal growth in heterozygous knockout animals (Lmx1b (+/-)) compared to Lmx1b (+/+) animals, which was correlated with a significantly lower increase in glomerular volume (V(G)) (p = 0.0034) and an increase in glomerulosclerosis (p = 0.085). Thus, Lmx1b deficiency in heterozygous Lmx1b (Lmx1b (+/-)) knockout mice profoundly affects the compensatory response to nephron loss. Moreover, this is the first report of a phenotype in heterozygous Lmx1b (Lmx1b ( +/-)) knockout animals.

Renoprotective effects of fenofibrate in diabetic rats are achieved by suppressing kidney plasminogen activator inhibitor-1

To investigate mechanisms of protective effects of fenofibrate on the diabetic kidney, male Wistar rats were divided into control, untreated diabetes, and fenofibrate-treated (32 mg kg − 1 d − 1 , 8 weeks) diabetes groups. Diabetes induced by streptozotocin (25 mg/kg) and a high-fat diet was characterized by the disorders of plasma glucose and lipids. In untreated diabetic rats, there were increases in glomerular volume, matrix content, expressions of laminin and urinary albumin excretion. These nephropathies were associated with the upregulations of plasminogen activator inhibitor 1 (PAI-1) mRNA expression and its protein activity in the renal cortex, and a significant increase in transforming growth factor β1 (TGF-β1) expression. Treatment with fenofibrate suppressed the expression of PAI-I mRNA and its protein activity, and inhibited TGF-β1 overexpression. It also partially reversed metabolic disorders and pathophysiologic changes associated with diabetic nephropathy. Our results indicate that fenofibrate delays the progression of diabetic nephropathy in rats to some extent. These renoprotective effects are likely to be achieved through suppression of PAI-1 and TGF-β1 in the renal cortex, and consequently less extracellular matrix deposition.

Angiotensin II receptor blocker inhibits p27Kip1 expression in glucose-stimulated podocytes and in diabetic glomeruli

Diabetic nephropathy is characterized by glomerular and tubular hypertrophy, and angiotensin II receptor blockers (ARBs) are known to prevent renal hypertrophy in diabetic patients. To determine the effect of ARB on podocyte p27(Kip1) mRNA and protein expression, podocytes were exposed to 5.6 mmol/L normal glucose or 25 mmol/L high glucose with or without ARB, 10(-7) mol/L L-158,809. For animal studies, streptozotocin-induced diabetic rats were left untreated or were treated with 1 mg/kg/day L-158,809 for 3 months (diabetes mellitus + ARB). Competitive reverse transcription-polymerase chain reaction (RT-PCR), Western blot, immunohistochemistry, and morphometric analyses were performed. p27(Kip1) mRNA and protein expression in podocytes exposed to high glucose and in 3-month diabetic glomeruli were significantly increased (P < 0.01). High glucose significantly increased angiotensin II levels both in cell lysates and in media compared with normal glucose (P < 0.05) and exogenous angiotensin II also increased p27(Kip1) mRNA and protein expression in podocytes. L-158,809 treatment in podocytes inhibited the increase in p27(Kip1) mRNA expression by 84%, and protein expression by 89% (P < 0.05). p27(Kip1) mRNA and protein expression in diabetic + ARB glomeruli were also significantly reduced by 78% and 85%, respectively, compared with diabetic glomeruli (P < 0.01). ARB treatment also significantly ameliorated increased glomerular p27(Kip1) expression in diabetes mellitus as assessed by immunohistochemistry (P < 0.01). The increase in glomerular volume in diabetes mellitus was also inhibited by 81% with ARB treatment (P < 0.05). p27(Kip1) mRNA and protein expression were increased in diabetic glomeruli as well as in high glucose-stimulated podocytes, and this increment in p27(Kip1) expression was ameliorated by ARB treatment. These findings indicate that ARB treatment has an additional effect on preventing renal hypertrophy in diabetes mellitus.

Inhibition of Vascular Endothelial Growth Factor (VEGF) Does Not Affect Early Renal Changes in a Rat Model of Lean Type 2 Diabetes

Type 2 diabetes is the most frequent cause of end-stage renal failure in many Western countries. Approximately 10-15 % of all type 2 diabetics are lean. Various growth factors and cytokines have been implicated in the pathophysiology of diabetic kidney disease, including vascular endothelial growth factor (VEGF). To elucidate a role for VEGF in the renal changes associated with type 2 diabetes, we examined the effect of a VEGF-antibody (ab) on early renal changes in the Goto-Kakizaki (GK) rat, a lean type 2 diabetes model. GK-rats were treated for 6 weeks with the VEGF-ab or with an isotype-matched irrelevant IgG. Wistar rats were used as non-diabetic controls. Placebo-treated GK-rats showed a pronounced increase in glomerular volume and urinary albumin excretion (UAE) and no change in the renal expression of endothelial nitric oxide synthase (eNOS) compared to placebo-treated non-diabetic controls. Kidney weight and creatinine clearance were no different between the groups. VEGF-ab treatment had no effect on glomerular volume, UAE, eNOS expression, body weight, blood glucose levels or food intake, but lowered serum insulin levels in non-diabetic and diabetic animals. We conclude that VEGF inhibition has minimal effects on early renal changes in GK-rats.

Serum cystatin C reflects glomerular endotheliosis in normal, hypertensive and pre-eclamptic pregnancies

Objective To study the correlation between serum cystatin C levels and renal structural changes in normal, hypertensive and pre-eclamptic pregnancy to evaluate it as a marker of the degree of renal involvement in pre-eclampsia. Design An observational prospective study. Setting University Hospital of Lund, Sweden. Sample Thirty-six women with hypertensive disease in pregnancy and 12 healthy pregnant women in the third trimester recruited from maternal health care centres in the catchment area of the hospital. Methods Renal biopsy samples were obtained from all participants and the degree of endotheliosis as well as the mean glomerular volume was evaluated by light microscopy in silver methenamin-stained sections. Serum cystatin C levels were measured and correlated to the structural changes. Main outcome measures Correlation among degree of glomerular endotheliosis, glomerular volume andserum cystatin C. Results Serum cystatin C levels differed between the different degrees of endotheliosis, showing a highly significant increasing linear trend. They also correlated significantly with glomerular volume ( r = 0.60, P < 0.001). Mean serum urate and creatinine levels also increased with the degree of endotheliosis, but not above the reference interval for normal term pregnancy, even in pre-eclamptic women. Conclusion Serum cystatin C may be used as a marker, not only for impaired renal function, but also for the degree of glomerular endotheliosis and increase in glomerular volume in pregnancy. It may be of value in the monitoring of pregnancies complicated by pre-eclampsia.

Serum cystatin C reflects glomerular endotheliosis in normal, hypertensive and pre‐eclamptic pregnancies

To study the correlation between serum cystatin C levels and renal structural changes in normal, hypertensive and pre-eclamptic pregnancy to evaluate it as a marker of the degree of renal involvement in pre-eclampsia. An observational prospective study. University Hospital of Lund, Sweden. Thirty-six women with hypertensive disease in pregnancy and 12 healthy pregnant women in the third trimester recruited from maternal health care centres in the catchment area of the hospital. Renal biopsy samples were obtained from all participants and the degree of endotheliosis as well as the mean glomerular volume was evaluated by light microscopy in silver methenamin-stained sections. Serum cystatin C levels were measured and correlated to the structural changes. Correlation among degree of glomerular endotheliosis, glomerular volume and serum cystatin C. Serum cystatin C levels differed between the different degrees of endotheliosis, showing a highly significant increasing linear trend. They also correlated significantly with glomerular volume (r = 0.60, P < 0.001). Mean serum urate and creatinine levels also increased with the degree of endotheliosis, but not above the reference interval for normal term pregnancy, even in pre-eclamptic women. Serum cystatin C may be used as a marker, not only for impaired renal function, but also for the degree of glomerular endotheliosis and increase in glomerular volume in pregnancy. It may be of value in the monitoring of pregnancies complicated by pre-eclampsia.