Being Born Large for Gestational Age is Associated with Increased Global Placental DNA Methylation.

Being born small (SGA) or large for gestational age (LGA) is associated with adverse birth outcomes and metabolic diseases in later life of the offspring. It is known that aberrations in growth during gestation are related to altered placental function. Placental function is regulated by epigenetic mechanisms such as DNA methylation. Several studies in recent years have demonstrated associations between altered patterns of DNA methylation and adverse birth outcomes. However, larger studies that reliably investigated global DNA methylation are lacking. The aim of this study was to characterize global placental DNA methylation in relationship to size for gestational age. Global DNA methylation was assessed in 1023 placental samples by LC-MS/MS. LGA offspring displayed significantly higher global placental DNA methylation compared to appropriate for gestational age (AGA; p < 0.001). ANCOVA analyses adjusted for known factors impacting on DNA methylation demonstrated an independent association between placental global DNA methylation and LGA births (p < 0.001). Tertile stratification according to global placental DNA methylation levels revealed a significantly higher frequency of LGA births in the third tertile. Furthermore, a multiple logistic regression analysis corrected for known factors influencing birth weight highlighted an independent positive association between global placental DNA methylation and the frequency of LGA births (p = 0.001).

Increased global placental DNA methylation levels are associated with gestational diabetes.

BACKGROUND: Gestational diabetes mellitus (GDM) is associated with adverse pregnancy outcomes. It is known that GDM is associated with an altered placental function and changes in placental gene regulation. More recent studies demonstrated an involvement of epigenetic mechanisms. So far, the focus regarding placental epigenetic changes in GDM was set on gene-specific DNA methylation analyses. Studies that robustly investigated placental global DNA methylation are lacking. However, several studies showed that tissue-specific alterations in global DNA methylation are independently associated with type 2 diabetes. Thus, the aim of this study was to characterize global placental DNA methylation by robustly measuring placental DNA 5-methylcytosine (5mC) content and to examine whether differences in placental global DNA methylation are associated with GDM. METHODS: Global DNA methylation was quantified by the current gold standard method, LC-MS/MS. In total, 1030 placental samples were analyzed in this single-center birth cohort study. RESULTS: Mothers with GDM displayed a significantly increased global placental DNA methylation (3.22 ± 0.63 vs. 3.00 ± 0.46 %; p = 0.013; ±SD). Bivariate logistic regression showed a highly significant positive correlation between global placental DNA methylation and the presence of GDM (p = 0.0009). Quintile stratification according to placental DNA 5mC levels revealed that the frequency of GDM was evenly distributed in quintiles 1-4 (2.9-5.3 %), whereas the frequency in the fifth quintile was significantly higher (10.7 %; p = 0.003). Bivariate logistic models adjusted for maternal age, BMI, ethnicity, recurrent miscarriages, and familiar diabetes predisposition clearly demonstrated an independent association between global placental DNA hypermethylation and GDM. Furthermore, an ANCOVA model considering known predictors of DNA methylation substantiated an independent association between GDM and placental DNA methylation. CONCLUSIONS: This is the first study that employed a robust quantitative assessment of placental global DNA methylation in over a thousand placental samples. The study provides large scale evidence that placental global DNA hypermethylation is associated with GDM, independent of established risk factors.

Renal outcome in equipotent antihypertensive treatment with telmisartan, ramipril and in combination in SHR-SP rats.

BACKGROUND: The ONTARGET trial revealed an association of ACEI/ARB combination treatment (telmisartan and ramipril) with adverse renal outcome versus respective monotherapy; preclinical evidence regarding renal outcome in ACEI/ARB combination treatment is scarce. METHODS: Spontaneously hypertensive stroke prone rats (SHR-SP) rats on a salt-rich diet were randomly allocated to 4 groups: SHR (untreated, n = 24), SHR + telmisartan (SHR-T, 2.39 +/- 0.69 mg/kg bw; n = 27), SHR + ramipril (SHR-R, 6.28 +/- 3.48 mg/kg bw; n = 27) and combination treatment (SHR-TR, 0.51 +/- 0.14 mg/kg bw; same dose for telmisartan and ramipril; n = 26). Study duration was 12 weeks, blood pressure was assessed weekly and doses were adjusted to maintain equal blood pressure. Finally, blood and urine samples were obtained and kidneys were harvested for histological studies. RESULTS: Blood pressure in untreated rats rose to a maximum of 239 mmHg, whereas in all treatment groups it remained stable between 140 and 150 mmHg. Mortality was 50% in the untreated group, whereas all treatment groups survived completely. Renal function--as indicated by plasma urea and cystatin c--was significantly worse in SHR-TR animals compared to all other groups. With plasma creatinine a similar trend was observed. All treatment options significantly decreased albuminuria. Renal glomerulosclerosis was decreased by monotherapy, whereas combination therapy failed to have a significant effect. Interstitial fibrosis was decreased to a similar extent by all treatment options. CONCLUSIONS: ACEI/ARB combination treatment failed to render significant additional benefits on renal outcome in hypertensive rats when compared to monotherapy. Instead our data indicate that dual RAAS blockade might have an adverse effect on kidney function and histology when compared to monotherapy in salt-loaded SHR-SP.

Impact of maternal body mass index on neonatal outcome.

INTRODUCTION: Maternal body mass index has an impact on maternal and fetal pregnancy outcome. An increased maternal BMI is known to be associated with admission of the newborn to a neonatal care unit. The reasons and impact of this admission on fetal outcome, however, are unknown so far. OBJECTIVE: The aim of our study was to investigate the impact of maternal BMI on maternal and fetal pregnancy outcome with special focus on the children admitted to a neonatal care unit. METHODS: A cohort of 2049 non-diabetic mothers giving birth in the Charite university hospital was prospectively studied. The impact of maternal BMI on maternal and fetal outcome parameters was tested using multivariate regression analysis. Outcome of children admitted to a neonatal ward (n = 505) was analysed. RESULTS: Increased maternal BMI was associated with an increased risk for hypertensive complications, peripheral edema, caesarean section, fetal macrosomia and admission of the newborn to a neonatal care unit, whereas decreased BMI was associated with preterm birth and lower birthweight. In the neonatal ward children from obese mothers are characterized by hypoglycaemia. They need less oxygen, and exhibit a shorter stay on the neonatal ward compared to children from normal weight mothers, whereas children from underweight mothers are characterized by lower umbilical blood pH and increased incidence of death corresponding to increased prevalence of preterm birth. CONCLUSION: Pregnancy outcome is worst in babies from mothers with low body mass index as compared to healthy weight mothers with respect to increased incidence of preterm birth, lower birth weight and increased neonate mortality on the neonatal ward. We demonstrate that the increased risk for neonatal admission in children from obese mothers does not necessarily indicate severe fetal impairment.

Novel renal replacement strategies for the elimination of serum free light chains in patients with kappa light chain nephropathy.

Multiple myeloma (MM) is a malignancy with excessive production of monoclonal proteins. At disease presentation 30% of MM patients have significant renal impairment which may progress to renal failure requiring dialysis. Besides chemotherapy extracorporeal elimination procedures such as plasma exchange have been applied as adjuvant strategies to eliminate free light chains from circulating blood, however the efficacy was poor with older techniques. We report about a highly efficient method to eliminate serum free light chain (sFLC) using a newly designed protein leaking membrane in patients suffering from sFLC induced acute renal failure. The protein leaking membrane (HCO 1100) is characterized by increased pore size facilitating elimination of middle molecules such as sFLC kappa (22.5 kD). The HCO 1100 membrane was applied in a hemodialysis and hemodiafiltration mode and compared to standard procedures (high flux hemodialysis, hemodiafiltration and plasma exchange). Hemodiafiltration with the protein leaking membrane HCO 1100 was superior to all other extracorporeal replacement strategies in eliminating sFLC-kappa from circulating blood. A median blood reduction rate of 40.8% (range 13.9%-66.4%) was achieved during hemodiafiltration. The corresponding peak clearance rate was 25 ml/min. Importantly, the poorest elimination rate was achieved by plasma exchange followed by standard high flux hemodialysis. Extracorporeal elimination strategies with the protein leaking membrane HCO 1100 may be a promising adjuvant treatment strategy for patients with sFLC nephropathy requiring dialysis. Hemodiafiltration and to lesser extend also hemodialysis with the HCO 1100 hemofilter are able to eliminate substantial amounts of sFLC kappa in MM patients.

Renal phenotype of ET-1 transgenic mice is modulated by androgens.

INTRODUCTION: Activation of the endothelin (ET) system promotes inflammation and fibrosis in various tissues including the kidney. Male ET-1 transgenic mice are characterized by chronic kidney inflammation and renal scarring. We hypothesized that this renal phenotype might be modulated by androgens. Thus the aim of our study was to elucidate the impact of gonadectomy in ET-1 transgenic mice on kidney function and morphology. - METHODS: Male ET-1 transgenic mice at the age of 10 weeks were randomly allocated to the following groups: normal ET transgenic mice (ET; n = 17) and ET transgenic mice that underwent castration (ET + cas; n = 12). Study duration was 9 months. Creatinine clearance and protein excretion was monitored. At study end animals were sacrificed and kidneys were harvested for histology/immunhistochemistry. RESULTS: Castration significantly ameliorated glomerulosclerosis in ET-1 transgenic mice (ET glomerulosclerosis-score: 3.0 +/- 0.17 vs ET+cas: 2.4 +/- 0.17; p < 0.05) as well as renal perivascular fibrosis (ET fibrosis-score: 3.0 +/- 0.14 vs ET + cas: 2.2 +/- 0.14; p < 0.05). However, interstitial fibrosis and media/lumen-ratio of renal arteries remained unaffected by castration. Regarding inflammation, castration significantly reduced the number of CD4-positive cells in renal tissue of ET-1 transgenic mice (ET CD4-positive cells/10000 cells: 355 +/- 72 vs ET + cas: 147 +/- 28; p < 0.05). Renal tissue contents of CD8 positive cells as well as of macrophages were not affected by castration. Regarding kidney function castration significantly reduced proteinuria in ET-1 transgenic mice whereas creatinine clearance did not differ between study groups. CONCLUSION: Our study demonstrates that the renal histopathological phenotype in male ET-1 transgenic mice with regard to glomerulosclerosis, proteinuria, perivascular fibrosis and immune cell immigration is ameliorated by castration. We thus conclude that the effects of ET-1 overexpression on renal tissue injury are modulated by androgens.

Impact of maternal endothelial nitric oxide synthase gene polymorphisms on blood pressure, protein excretion and fetal outcome in pregnancy.

A genetic association study was conducted to assess whether genetically determined alterations of the nitric oxide system are associated with clinical markers of pre-eclampsia. A large number of Caucasian women were consecutively included after delivery and genotyped for the endothelial nitric oxide synthase gene (NOS3) polymorphisms G894T, T789C (n=1502) and intron 4a/b (n=2186). There are no significant differences in mean blood pressure (BP), protein excretion or new-onset peripheral oedema between any of the genotypes over the course of pregnancy. Neither particular haplotypes nor the combined presence of any two alleles is associated with those markers of pre-eclampsia. The maternal polymorphisms do not seem to influence fetal growth, birth weight or the incidence of congenital malformations. We demonstrate in a large Caucasian population that maternal polymorphisms of the NOS3 gene are not related to clinical markers of pre-eclampsia. The functional relevance of the NOS3 variants alone does not seem to be strong enough to affect BP regulation during pregnancy.

The adenosine A1 receptor antagonist SLV320 reduces myocardial fibrosis in rats with 5/6 nephrectomy without affecting blood pressure.

BACKGROUND AND PURPOSE: Myocardial fibrosis is an unwanted effect associated with chronic renal failure. The adenosine system is involved in cardiac and renal function. Therefore, we investigated the novel selective adenosine A(1) receptor antagonist SLV320 focusing on its potential in preventing cardiomyopathy in rats with 5/6 nephrectomy. EXPERIMENTAL APPROACH: Male Sprague-Dawley rats were allocated to 4 groups of 12 rats each: 5/6 nephrectomy (5/6 NX), 5/6 NX plus SLV320 (10 mg kg(-1) d(-1) mixed with food), sham and sham plus SLV320. Study duration was 12 weeks, blood pressure was assessed repeatedly. At study end kidney function was assessed, blood samples and hearts were taken for histology/immunohistochemistry. Pharmacological properties of SLV320 were assessed using receptor binding and enzyme assays and in vivo. KEY RESULTS: SLV320 is a selective and potent adenosine A(1) antagonist in vitro (Ki=1 nM) with a selectivity factor of at least 200 versus other adenosine receptor subtypes. Functional A(1) antagonism was demonstrated in vivo. In rats with 5/6 NX SLV320 significantly decreased albuminuria by about 50%, but did not alter glomerular filtration rate (GFR). SLV320 normalized cardiac collagen I+III contents in 5/6 NX rats. SLV320 prevented nephrectomy-dependent rise in plasma levels of creatinine kinase (CK), ALT and AST. Blood pressure did not differ between study groups. CONCLUSION: SLV320 suppresses cardiac fibrosis and attenuates albuminuria without affecting blood pressure in rats with 5/6 nephrectomy, indicating that selective A(1) receptor antagonists may be beneficial in uraemic cardiomyopathy.

High-protein nutrition during pregnancy and lactation programs blood pressure, food efficiency, and body weight of the offspring in a sex-dependent manner.

Maternal low-protein diet during pregnancy is a risk factor for cardiovascular disease of the offspring in later life. The impact of high-protein diet during pregnancy on the cardiovascular phenotype of the offspring, however, is still unknown. We examined the influence of a high-protein diet during pregnancy and lactation on the renal, hemodynamic, and metabolic phenotype of the F1 generation. Female Wistar rats were either fed a normal protein diet (20% protein: NP) or an isocaloric high-protein diet (40% protein: HP) throughout pregnancy and lactation. At weaning, the offspring were fed with standard diet, and they were allocated according to sex and maternal diet to four groups: normal-protein male (NPm, n = 25), normal-protein female (NPf, n = 19), high-protein male (HPm, n = 24), high-protein female (HPf, n = 29). During the experiment (22 wk), the animals were characterized by repeated measurement of body weight, food intake, blood pressure, glucose tolerance, energy expenditure, and kidney function. At the end of the study period histomorphological analyses of the kidneys and weight measurement of reproductive fat pads were conducted. There were no differences in birth weight between the study groups. No influence of maternal diet on energy expenditure, glucose tolerance, and plasma lipid levels was detected. Blood pressure and glomerulosclerosis were elevated in male offspring only, whereas female offspring were characterized by an increased food efficiency, higher body weight, and increased fat pads. Our study demonstrates that a high-protein diet during pregnancy and lactation in rats programs blood pressure, food efficiency, and body weight of the offspring in a sex-dependent manner.

Rapid immunochromatographic strip test for the detection of albuminuria and brief literature review on albuminuria screening.

Albuminuria is a powerful predictor of cardiovascular events in diabetic and hypertensive patients as well as in the general population. In the present study we evaluated the diagnostic performance of the new PreventID Albumin test, a semi-quantitative immunochromatographic dipstick device for the rapid detection of low concentrations of urinary albumin (microalbuminuria). 88 randomly selected fresh urine samples from the central clinical laboratory of the Charité, Berlin/Germany were analysed. The diagnostic accuracy of the PreventID Albumin test for the detection of urinary albumin excretion >18 mg/l was assessed by comparing the results with urinary albumin excretion determined by immunoturbidimetry as golden standard. In comparison with immunoturbidimetry the PreventID Albumin test had a sensitivity of 96.2% and specificity of 97.1%. False negative results were found in 2.3% and false positive results were obtained in 1.1% of specimens. These findings suggest that the PreventID Albumin test may be a useful and valid method for the screening of albuminuria. However, it should not be regarded as a diagnostic test. Positive results should be followed by quantification of urinary albumin or albumin/creatinine ratio by a laboratory based method.

Strong acceleration of murine lupus by injection of the SmD1(83-119) peptide.

OBJECTIVE: The mechanisms of IgG anti-double-stranded DNA (anti-dsDNA) antibody induction are incompletely understood. We recently demonstrated a high prevalence of autoantibodies to the C-terminus of SmD1 in patients with systemic lupus erythematosus (SLE) that was closely associated with anti-dsDNA reactivity. The aim of the present study was to analyze the influence of the SmD1 C-terminus on the generation of pathogenic anti-dsDNA antibodies in a murine model of SLE. METHODS: Female lupus-prone prenephritic (NZB x NZW)F1 mice (NZB/NZW mice) as well as female control BALB/c, NZW, and (BALB/c x NZW)F, mice (CWF1 mice) were subcutaneously injected with keyhole limpet hemocyanin (KLH)-coupled SmD1(83-119). Controls received injections of recombinant SmD1 (rSmD1), KLH-rSmD1, KLH-coupled randomized peptide of SmD1(83-119), ovalbumin, or saline. Animals were monitored for survival and proteinuria and for levels of plasma creatinine, urea, and autoantibodies. In addition, histologic examinations were performed and T cell responses against SmD1(83-119) peptide and rSmD1 protein were determined in SmD1(83-119)-treated and -untreated NZB/NZW mice. RESULTS: Immunization with KLH-SmD1(83-119), but not with control peptide, significantly accelerated the natural course of lupus in NZB/NZW mice, with premature renal failure and increased development of anti-dsDNA antibodies. Control strains of mice remained healthy, with no relevant anti-SmD1(83-119) antibodies detectable even after immunization. In contrast to findings in control mice, a T cell response against SmD1(83-119) was already present in unmanipulated NZB/NZW mice, and this response was further amplified after immunization. CONCLUSION: The SmD1(83-119) peptide can influence the pathogenic anti-dsDNA response in the NZB/NZW murine lupus model. The data suggest that an SmD1(83-119)-specific T cell response is critical. Therefore, modulation of these autoantigen-specific T cells by tolerance induction may provide a therapeutic approach to specific immunosuppression in lupus.

Hypokalemic nephropathy after pelvic pouch procedure and protective loop ileostomy.

Proctocolectomy with ileal pouch-anal anastomosis and temporary ileostomy has been established as a curative operation in severe ulcerative colitis during the last 2 decades. Electrolyte imbalances during the first postoperative weeks until ileostomy closure have been reported previously. Here we report about a 70-year-old male patient with a 38 year-history of severe ulcerative colitis who developed slowly progressive renal failure after proctocolectomy with ileal pouch-anal anastomosis and temporary ileostomy. He was referred to our centre with a serum creatinine of 818 micromol/L, hypokalemia of 2.83 mmol/L and metabolic alkalosis as a patient with suspected end-stage renal disease in order to perform shunt surgery and start chronic hemodialysis. However, hypokalemia and metabolic alkalosis are not typical for end-stage renal disease, and renal biopsy showed typical signs of hypokalemic nephropathy. Our patient almost completely recovered after ileostomy closure. This case clearly shows that temporary ileostomy in patients who underwent proctocolectomy, e. g. for ulcerative colitis, is associated with a risk of hypokalemic nephropathy. The appropriate and definite therapy is a surgical one, i. e. ileostomy closure. Monitoring metabolic changes after proctocolectomy and ileostomy, especially during the defunctionalized stage when temporary ileostomy is still present, is essential.

Renin angiotensin system gene polymorphisms in pediatric renal transplant recipients.

Genetic variability in the renin angiotensin system may modify renal responses to injury and disease progression. We therefore examined whether the insertion/deletion polymorphism of the angiotensin-converting enzyme (ACE) gene, the Met235-->Thr polymorphism of the angiotensinogen (AGT) gene, and the A1166-->C polymorphism of the angiotensin II type 1 receptor gene (ATR1) were associated with disease progression and outcome after renal transplantation (Tx) in 100 Caucasian pediatric renal transplant recipients. The observed allele frequencies were: DD 31%, DI 41% and II 28%, for ACE; MM 42%, MT 37% and TT 21%, for the methionine (Met)235-->threonine (Thr) polymorphism of AGT; and AA 51%, AC 38% and CC 11%, for the adenine (A)1166-->cytosine (C) gene polymorphism. The slope of 1/creatinine was determined by linear regression analysis of a median of 12 points before and after renal Tx, and the population was divided in two equal groups, according to the slope, both before and after Tx. There were no statistically significant differences for AGT, ACE, and ATR1 polymorphisms with regard to the slope of 1/creatinine before renal Tx. After renal Tx, the ACE II genotype (p = 0.024, chi-square test) and the presence of the I allele (p=0.033, chi-square test) were associated with a favorable slope of 1/creatinine. There was no association of the AGT or the ATR1 polymorphism with outcome after renal Tx, and none of the genotypes were associated with hypertension before or after renal Tx. We suggest that the beneficial association of disease progression after renal Tx with the II genotype and/or the presence of the I allele in our pediatric cohort might be explained by a lower activity of the circulating ACE enzyme associated with the I allele.

CC chemokine receptor 5 and renal-transplant survival.

BACKGROUND: About 1% of white populations are homozygous carriers of an allele of the gene for the CC chemokine receptor 5 (CCR5) with a 32 bp deletion (CCR5Delta32), which leads to an inactive receptor. During acute and chronic transplant rejection, ligands for CCR5 are upregulated, and the graft is infiltrated by CCR5-positive mononuclear cells. We therefore investigated the influence of CCR5Delta32 on renal-transplant survival. METHODS: Genomic DNA from peripheral-blood leucocytes of 1227 renal-transplant recipients was screened by PCR for the presence of CCR5Delta32. Demographic and clinical data were extracted from hospital records. Complete follow-up data were available for 576 recipients of first renal transplants. Graft survival was analysed by Fisher's exact test and Kaplan-Meier plots compared with a log-rank test. FINDINGS: PCR identified 21 patients homozygous for CCR5Delta32 (frequency 1.7%). One patient died with a functioning graft. Only one of the remaining patients lost transplant function during follow-up (median 7.2 years) compared with 78 of the 555 patients with a homozygous wild-type or heterozygous CCR5Delta32 genotype. Graft survival was significantly longer in the homozygous CCR5Delta32 group than in the control group (log-rank p=0.033; hazard ratio 0.367 [95% CI 0.157-0.859]). INTERPRETATION: Patients homozygous for CCR5Delta32 show longer survival of renal transplants than those with other genotypes, suggesting a pathophysiological role for CCR5 in transplant loss. This receptor may be a useful target for the prevention of transplant loss.

Hemodynamic, renal, and endocrine responses to acute ET(A) blockade at different ANG II plasma levels.

Angiotensin (ANG) II effects may be partly mediated by endothelin (ET)-1. This study analyses the hemodynamic, renal, and hormonal responses of acute ET(A) receptor antagonism (LU-135252) at two ANG II plasma levels in eight conscious dogs. Protocol 1 involved a 60-min baseline, followed by two doses of ANG II for 60 min each (4 and 20 ng. kg(-1). min(-1)), termed ANG II 4 (slightly increased) and ANG II 20 (pathophysiologically increased ANG II plasma concentration). Protocol 2 was the same as protocol 1 but included 15 mg/kg iv LU-135252 after the baseline period. Protocol 3 was a 3-h time control. ANG II without LU-135252 did not increase plasma big ET-1 and ET-1, whereas LU-135252 increased ET-1 transiently after injection. This transient ET-1 increase was not reflected in urinary ET-1 excretion. The ANG II induced decreases in sodium, water, and potassium excretion, glomerular filtration rate, and fractional sodium excretion were not different with and without LU-135252. Mean arterial pressure increased during ANG II and was not lower with LU-135252 (-6 mmHg, not significant). Most importantly, during ANG II 20 LU-135252 prevented the decrease in cardiac output. Simultaneously, systemic vascular resistance increased 40% less, pulmonary vascular resistance was maintained at baseline levels, and central venous and wedge pressure were lower. Because ANG II stimulated endothelin de novo synthesis should just have started after 2 h of ANG II infusion, there must be mechanisms other than blocking the coupling of de novo synthesized endothelins to the ET(A) receptors to explain the effects of acute ET(A) receptor inhibition in our setting.

Impaired sodium excretion, decreased glomerular filtration rate and elevated blood pressure in endothelin receptor type B deficient rats.

The renal endothelin (ET) system, particularly the ET type B receptor, has been implicated in the regulation of sodium excretion and glomerular filtration rate (GFR). We analyzed kidney morphology and function in a rat strain characterized by complete absence of a functional ETB receptor. Due to Hirschsprung's disease limiting lifetime in these rats, studies were performed in 23-day-old rats. Kidney size and morphology (glomerular and interstitial matrix content, glomerular size and cell density and intrarenal vascular morphology) were normal in ETB-deficient rats. There were also no evidence of altered kidney cell cycle regulation in these rats. GFR was significantly lower, by 72% (P<0.001), in homozygous ETB-deficient rats than in wild-type rats. Fractional sodium excretion was likewise markedly reduced by 84% in homozygous ETB-deficient rats (P<0.001 versus wild-type rats). Treatment with the specific epithelial sodium channel blocker amiloride led to a much higher increase in fractional sodium excretion in ETB-deficient rats (934.2+/-73% in ETB-deficient rats versus 297+/-20% in wild-type rats, expressed as percentage of corresponding placebo treated control; P<0.001). Mean arterial blood pressure was elevated by 7.9 mmHg in homozygous ETB-deficient rats (P<0.05 versus wild-type rats). Our study demonstrates that ETB-deficiency causes early onset kidney dysfunction characterized by a markedly reduced sodium excretion, decreased GFR, and slightly elevated blood pressure. The complete absence of the ETB receptor causes in the kidney--in contrast to the colon--a functional rather than a developmental, neural crest cell dependent disease, since kidney morphology was normal in ETB-deficient rats. The much higher increase in the fractional sodium excretion in ETB-deficient rats after pharmacological blockade of the epithelial sodium channel indicates that the decreased fractional sodium excretion in ETB-deficient rats is most probably due to a lack of the inhibitory property of the ETB receptor on the epithelial sodium channel activity.

Effects of endothelin receptor antagonists on the progression of diabetic nephropathy.

BACKGROUND: Diabetic nephropathy is the leading cause of end-stage renal disease in European countries and is associated with an enhanced renal synthesis of endothelin (ET)-1. ETs are - beside their potent vasoconstrictor properties - very potent profibrotic acting paracrine hormones especially in the kidney. METHODS: We analyzed in rats with streptozotocin-induced diabetes the effects of an ETA-type (ETA) receptor antagonist (LU 135252) in comparison to a combined ETA/ETB receptor antagonist (LU 224332) on the expression of interstitial and glomerular collagen type I, III and IV as well as on fibronectin and laminin by quantitative immunohistochemistry using a computer-aided image analysis system. Global glomerular matrix deposition was analyzed after PAS staining. In addition to the morphometric examination of the kidneys, we also investigated GFR, urinary albumin and total protein excretion. The diabetic rats were treated for 36 weeks. RESULTS: Treatment with either LU 135252 or LU 224332 normalized the amount of PAS-positive material within the glomeruli. The expression of glomerular fibronectin and type IV collagen was increased 36 weeks after induction of diabetes. The overexpression of these two matrix proteins within the glomeruli of diabetic rats was completely abolished by both ET receptor antagonists, whereas protein excretion was only reduced by about 50% as compared to diabetic rats without treatment. CONCLUSION: The present study indicates that ETA receptor antagonists as well as combined ETA/ETB receptor antagonists reduce proteinuria and completely normalize the renal matrix protein expression in hyperglycemic rats with streptozotocin-induced diabetes. The antifibrotic effect seems to be mediated via the ETA receptor. ET receptor antagonists might be a new approach in the treatment of diabetic nephropathy.

Reduction in left ventricular messenger RNA for transforming growth factor beta(1) attenuates left ventricular fibrosis and improves survival without lowering blood pressure in the hypertensive TGR(mRen2)27 Rat.

Angiotensin II recruits transforming growth factor beta(1) (TGFbeta(1)) and is related to left ventricular fibrosis. However, it is unclear whether chronic in vivo reduction in left ventricular TGFbeta(1) expression blunts fibrosis and improves outcome in angiotensin II-dependent hypertension. Four-week-old male hypertensive TGR(mRen2)27 (Ren2) rats received either normal food, low-dose losartan (0.5 mg. kg(-1). d(-1)), or tranilast (a nonspecific TGFbeta inhibitor; 400 mg. kg(-1). d(-1)) (n=10 for each group) for 12 weeks and were compared with Sprague-Dawley control rats. The effect of tranilast on survival was evaluated in 34 additional untreated homozygous Ren2 rats. Tranilast or low-dose losartan did not lower blood pressure. However, the increase in left ventricular weight (Ren2 versus SD 3.1+/-0.16 versus 2.1+/- 0.06 mg/g body wt; P<0.05) was significantly (P<0.05) blunted by both tranilast (2.7+/-0.05) and losartan (2.7+/-0.07). Both drugs prevented the increase in left ventricular TGFbeta(1) mRNA and fibronectin mRNA and blunted the increase in hydroxyproline content and the increase in perivascular fibrosis. The perivascular fibrosis score correlated significantly with the level of expression of TGFbeta(1) (r=0.62; P=0.019). In situ hybridization demonstrated increases in TGFbeta(1) mRNA, predominantly in perivascular and nonmyocyte areas. Both drugs did not prevent the decrease in systolic or diastolic dP/dt, but tranilast significantly improved the survival of untreated Ren2 rats (P=0.029). In conclusion, TGFbeta(1) mRNA expression is increased predominantly in nonmyocyte regions in the hypertrophied left ventricle in this angiotensin II-dependent model of hypertension. This increase is probably due to high angiotensin II levels rather than to hypertension. This is the first study to suggest that chronic inhibition of TGFbeta(1) expression attenuates left ventricular hypertrophy and fibrosis, even without lowering blood pressure.