Reduction of proteinuria with angiotensin receptor blockers

Losartan ameliorates renal fibrosis by inhibiting tumor necrosis factor signal pathway

Losartan is widely used in the treatment of chronic kidney disease (CKD) and has achieved good clinical efficacy, but its exact mechanism is not clear. We performed high-throughput sequencing (HTS) technology to screen the potential target of losartan in treating CKD. According to the HTS results, we found that the tumor necrosis factor (TNF) signal pathway was enriched. Therefore, we conducted in vivo and in vitro experiments to verify it. We found that TNF signal pathway was activated in both unilateral ureteral obstruction (UUO) rats and human proximal renal tubular epithelial cells (HK-2) treated with transforming growth factor-β1 (TGF-β1), while losartan can significantly inhibit TNF signal pathway as well as the expression of fibrosis related genes (such as COL-1, α-SMA and Vimentin). These data suggest that losartan may ameliorate renal fibrosis through modulating the TNF pathway.

Losartan metabolite EXP3179 is a unique blood pressure-lowering AT1R antagonist with direct, rapid endothelium-dependent vasoactive properties

BACKGROUND AND PURPOSE

Losartan is an anti-hypertensive angiotensin II (ANGII) type 1 receptor (AT1R) blocker (ARB) with many unexpected therapeutic properties, even in non-blood pressure (BP)-related diseases. Administered as a prodrug, losartan undergoes serial metabolism into EXP3179, a metabolite alleged to lack AT1R-blocking properties, and EXP3174, the dominant AT1R antagonist. Having observed that losartan can decrease vascular tone in mice with low AT1R expression and inhibit Marfan aortic widening at very high doses, we investigated whether EXP3179 may have unique, AT1R-independent effects on vascular tone and endothelial function.

EXPERIMENTAL APPROACH

We compared the AT1R blocking capabilities of EXP3179 and EXP3174 using AT1R-expressing cell lines. Their BP lowering and vasoactive properties were studied in normal, hypertensive and transgenic rodents, and ex vivo wire myography.

KEY RESULTS

We observed that both EXP3179 and EXP3174 can fully block (100%) AT1R signaling in vitro and significantly decrease BP in normotensive and spontaneously hypertensive rats. Only EXP3179 prevented PE-induced contraction by up to 65% (p < 0.01) in L-NAME and endothelium removal-sensitive fashion. Use of transgenic mice revealed that these effects involve the eNOS/caveolin-1 axis and the endothelium-dependent hyperpolarization factor (EDHF).

CONCLUSION AND IMPLICATIONS

We provide direct structure-activity evidence that EXP3179 is a BP-lowering AT1R blocker with unique endothelial function-enhancing properties not shared with losartan or EXP3174. The major pharmacological effects of losartan in patients are therefore likely more complex than simple blockade of AT1R by EXP3174, which helps rationalize its therapeutic and prophylactic properties, especially at very high doses. Reports relying on EXP3179 as an AT1R-independent losartan analogue may require careful re-evaluation.

Studying Telmisartan Plasma Exposure, Kidney Distribution, Receptor Occupancy, and Response in Patients With Type 2 Diabetes Using [11 C]Telmisartan

The angiotensin receptor blocker telmisartan slows progression of kidney disease in patients with type 2 diabetes (T2D), yet many patients remain at high risk for progressive kidney function loss. The underlying mechanisms for this response variation might be attributed to differences in angiotensin-1 receptor occupancy (RO), resulting from individual variation in plasma drug exposure, tissue drug exposure, and receptor availability. Therefore, we first assessed the relationship between plasma telmisartan exposure and urinary-albumin-to-creatinine-ratio (UACR) in 10 patients with T2D and albuminuria (mean age 66 years, median UACR 297 mg/g) after 4 weeks treatment with 80 mg telmisartan once daily. Increasing telmisartan exposure associated with a larger reduction in UACR (Pearson correlation coefficient (PCC) = -0.64, P = 0.046, median change UACR: -40.1%, 95% confidence interval (CI): -22.9 to -77.4%, mean telmisartan area under the curve (AUC) = 2927.1 ng·hour/mL, 95% CI: 723.0 to 6501.6 ng·hour/mL). Subsequently, we assessed the relation among plasma telmisartan exposure, kidney distribution, and angiotensin-1 RO in five patients with T2D (mean age 60 years, median UACR 72 mg/g) in a separate positron emission tomography imaging study with [¹¹ C]Telmisartan. Individual plasma telmisartan exposure correlated with telmisartan distribution to the kidneys (PCC = 0.976, P = 0.024). A meaningful RO could be calculated in three patients receiving 120 mg oral telmisartan, and although high exposure seems related to higher RO, with AUC_0-last of 31, 840, and 274 ng·hour/mL and corresponding RO values 5.5%, 44%, and 59%, this was not significant (P = 0.64). Together these results indicate, for the first time, a relationship among interindividual differences in plasma exposure, kidney tissue distribution, RO, and ultimately UACR response after telmisartan administration.

Genistein alleviates renin-angiotensin system mediated vascular and kidney alterations in renovascular hypertensive rats

Genistein is a bioflavonoid mainly found in soybean. This study evaluated the effect of genistein on vascular dysfunction and kidney damage in two-kidney, one-clipped (2K1C) hypertensive rats. Male Sprague-Dawley-2K1C hypertensive rats were treated with genistein (40 or 80 mg/kg) or losartan 10 mg/kg (n = 8/group). Genistein reduced blood pressure, attenuated the increase in sympathetic nerve-mediated contractile response and endothelial dysfunction in the mesenteric vascular beds and aorta of 2K1C rats. Increases in the intensity of tyrosine hydroxylase (TH) in the mesentery and plasma norepinephrine (NE) were alleviated in the genistein-treated group. Genistein also improved renal dysfunction, hypertrophy of the non-clipped kidney (NCK) and atrophy of the clipped kidney (CK) in 2K1C rats. Upregulation of angiotensin II receptor type I (AT₁R), nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunit 4 (Nox4) and Bcl2-associated X protein (BAX) and downregulation of B-cell lymphoma 2 (Bcl2) protein found in CK were restored by genistein. It also suppressed the overexpression of AT₁R, transforming growth factor beta I (TGF-β1), smad2/3 and p-smad3 in NCK. Genistein reduced serum angiotensin converting enzyme (ACE) activity and plasma angiotensin II (Ang II) in 2K1C rats. Low levels of catalase activity as well as high levels of superoxide generation and malondialdehyde (MDA) in 2K1C rats were restored by genistein treatment. In conclusion, genistein suppressed renin-angiotensin system-mediated sympathetic activation and oxidative stress in 2K1C rats. It alleviated renal atrophy in CK via modulation of AT₁R/NADPH oxidase/Bcl-2/BAX pathways and hypertrophy in NCK via AT₁R/TGF-β1/smad-dependent signalling pathways.

Prognostic significance of dipstick proteinuria in heart failure with preserved ejection fraction: insight from the PURSUIT-HFpEF registry

OBJECTIVE

The semiquantitative urine dipstick test is a simple and convenient method that is available in the smallest community-based healthcare clinics. We sought to clarify the prognostic significance of dipstick proteinuria in patients with heart failure (HF) with preserved ejection fraction (HFpEF).

DESIGN

A Prospective mUlticenteR obServational stUdy of patIenTs with Heart Failure with preserved Ejection Fraction (PURSUIT-HFpEF) registry.

PARTICIPANTS AND SETTING

We assessed 851 discharged-alive patients in the PURSUIT-HFpEF registry who were initially hospitalised due to an acute decompensated HFpEF (EF≥50%) and elevated N-terminal-pro-brain natriuretic peptide (≥400 ng/L) at Osaka University Hospital and other 30 affiliated hospitals in the Kansai region of Japan. Patients received a urine dipstick test, and were divided into two groups according to the absence or presence of proteinuria. A trace or more of dipstick proteinuria was defined as the presence of proteinuria.

MAIN OUTCOME MEASURES

A composite of cardiac death or HF rehospitalisation.

RESULTS

Median age was 83 years and 473 patients (55.6%) were female. Five hundred and two patients (59%) were proteinuria (-) and 349 patients (41%) were proteinuria (+). The composite endpoint and HF rehospitalisation occurred more often in proteinuria (+) individuals than proteinuria (-) individuals (log-rank p=0.006 and p=0.007, respectively); but cardiac death did not (log-rank p=0.139). Multivariable Cox regression analysis showed that the presence of proteinuria was associated with the composite endpoint (HR: 1.47, 95% CI 1.07 to 2.01, p=0.016), and HF rehospitalisation (HR: 1.48, 95% CI 1.07 to 2.05, p=0.020), but not with cardiac death (HR: 1.52, 95% CI 0.83 to 2.76, p=0.172).

CONCLUSIONS

Dipstick proteinuria may be a prognostic marker in patients with HFpEF. Evaluation of proteinuria by a urine dipstick test may be a simple but useful method for risk stratification in HFpEF.

UMIN-CTR ID

UMIN000021831.

Low-grade albuminuria is associated with high cardiovascular risk in CVD-free and normoalbuminuric Chinese adults: Results from the REACTION study

BACKGROUND

Data are limited with regard to the association between low-grade albuminuria (below the threshold of microalbuminuria) and high cardiovascular risk in normoalbuminuric Chinese adults free of cardiovascular disease (CVD).

METHODS

A total of 32 650 participants aged over 40 years from seven regional centers in China were included in this study. The single-void first morning urine sample was collected to measure the urinary albumin to creatinine ratio (UACR) and the data were divided into sex-specific quartiles. The Framingham Risk Score (FRS) was used to identify participants at high risk of developing coronary heart disease (CHD) over the next 10 years and the association between low-grade albuminuria and high 10-year Framingham risk for CHD (FRS ≥20%) was investigated.

RESULTS

Among males and females, the prevalence of cardiometabolic risk factors (diabetes, hypertension, and dyslipidemia) increased markedly with the elevation of UACR quartiles. Logistic regression analysis showed that the odds ratios (ORs) for high 10-year risk of CHD increased significantly from the second quartile in males (UACR: 4.78 ~ 7.53 mg/g, OR = 1.21, 95% confidence interval [CI]: 1.05-1.40) and the third quartile in females (UACR: 9.13 ~ 15.04 mg/g, OR = 3.07, 95% CI: 1.75-5.40). Stratified analysis showed that in males, the association was especially pronounced in elderly, overweight/obese participants and those without diabetes and hypertension whereas in females, the association was especially pronounced in elderly, overweight/obese participants and those without diabetes and with hypertension.

CONCLUSIONS

Low-grade albuminuria was significantly associated with high 10-year cardiovascular risk among CVD-free and normoalbuminuric Chinese adults.

Continuous hypergammaglobulinemia and proteinuria after the recovery of the visceral Leishmaniasis: a case report

BACKGROUND

Kidney involvement of visceral Leishmaniasis is previously reported, but knowledge is limited. Hypergammaglobulinemia is common in visceral leishmaniasis patients. Whether hypergammaglobulinemia after leishmaniasis depletion can cause kidney injury is not well reported yet.

CASE PRESENTATION

We reported a patient who recovered from visceral Leishmaniasis but showed persistent hypergammaglobulinemia and elevated urinary protein. Kidney biopsy showed glomerular hypertrophy with mild segmental mesangial proliferation without tubulointerstitial involvement in light microscopy. No immune complex deposit was found in the mesangial area by neither immunofluorescent staining nor electronic microscope. Increased lysosomes were observed in proximal tubules by electronic microscope. Valsartan was administered to decrease urinary protein, and no immune-suppressive therapy was added. The urinary protein and serum IgG level gradually dropped, and serum creatinine level remained stable during three- month follow up.

CONCLUSIONS

Hypergammaglobulinemia is unlikely to cause renal structural or functional damage in the short term. Angiotensin blockade significantly reduced urine protein, with a minor effect on IgG elimination.

Exercise-induced albuminuria increases over time in individuals with impaired glucose metabolism

Background

Exercise induced albuminuria (EiA) is elevated in patients with metabolic dysfunction and diabetes, and may serve as an early biomarker for endothelial dysfunction and “kidney reserve”. However, the change in EiA levels over time and its interaction with metabolic dysfunction and glucose metabolism has never been studied. Therefore, we sought to determine EiA levels over time in a cohort of individuals attending a routine annual health survey.

Methods

We prospectively enrolled 412 patients attending an annual healthy survey at our Medical Center. We collected urine samples for albumin and creatinine measurements before and immediately after completing an exercise stress test, along with multiple physiologic and metabolic parameters. Participants returned to a second follow up visit after a mean follow up period of 3 years (± 1.7 SD).

Results

Patients with diagnosed diabetes and subjects with HbA1c ≥ 6.5% significantly increased their EiA over time (median [IQR] change between visits = 19.5 [− 10.4–56.1] vs. − 1.1 [− 12.7–4.9] (p = 0.049) for diabetics vs non-diabetics respectively). Moreover, a diabetes diagnosis was significantly associated with a high increase in EiA over time (top 10th percentile) even after adjusting for age, BMI, eGFR, METs, self-reported history of heart disease, systolic and diastolic blood pressure; OR = 4.4 (1.01–19.3 95% CI) (p = 0.049). Finally, elevated fasting blood glucose (≥ 100 mg/dl) was the strongest and only significant predictor for a greater increase in EiA over time after adjusting for all five metabolic syndrome components; blood glucose, waist circumference, blood triglycerides, HDL cholesterol, and BP criteria; OR = 4.0 (1.6–9.8 95% CI) (p < 0.01).

Conclusions

Patients with diabetes and/or elevated fasting blood glucose increase their exercise-induced urinary albumin excretion over time. The ability of EiA to predict major clinical outcomes in patients with and without diabetes needs to be determined in future studies.

Two-Year Changes in Proteinuria and the Risk of Stroke in the Chinese Population: A Prospective Cohort Study

Background

Whether changes in proteinuria are associated with incident stroke in the general population is unclear. This study aimed to investigate the association between changes in proteinuria and incident stroke and its subtypes.

Methods and Results

The current study included 60 940 Chinese participants (mean age, 50.69 years) who were free of stroke at the time of surveys (2006–2007 and 2008–2009). Participants were divided into 4 categories according to 2‐year changes in proteinuria: no proteinuria, remittent proteinuria, incident proteinuria, and persistent proteinuria. Cox proportional hazards models were used to calculate hazard ratios and their 95% CIs for stroke. After a median follow‐up period of 6.92 years, 1769 individuals developed stroke. After adjustment for confounding factors, incident proteinuria and persistent proteinuria were associated with increased risk of stroke (hazard ratio, 1.46 [95% CI, 1.26–1.68] and hazard ratio, 1.71 [95% CI, 1.42–2.06], respectively) compared with no proteinuria, which were higher than proteinuria detected at one single point (hazard ratio, 1.25; 95% CI, 1.09–1.43). The effect size for risk of stroke subtypes including ischemic stroke and hemorrhagic stroke was similar.

Conclusions

Changes in proteinuria exposure, particularly persistent proteinuria, are more likely to reflect the risk of stroke, compared with proteinuria collected at a single time point in the general population.

Differential renal effects of candesartan at high and ultra-high doses in diabetic mice-potential role of the ACE2/AT2R/Mas axis

High doses of Ang II receptor (AT1R) blockers (ARBs) are renoprotective in diabetes. Underlying mechanisms remain unclear. We evaluated whether high/ultra-high doses of candesartan (ARB) up-regulate angiotensin-converting enzyme 2 (ACE2)/Ang II type 2 receptor (AT2R)/Mas receptor [protective axis of the of the renin–angiotensin system (RAS)] in diabetic mice. Systolic blood pressure (SBP), albuminuria and expression/activity of RAS components were assessed in diabetic db/db and control db/+ mice treated with increasing candesartan doses (intermediate, 1 mg/kg/d; high, 5 mg/kg/d; ultra-high, 25 and 75 mg/kg/d; 4 weeks). Lower doses candesartan did not influence SBP, but ultra-high doses reduced SBP in both groups. Plasma glucose and albuminuria were increased in db/db compared with db/+ mice. In diabetic mice treated with intermediate dose candesartan, renal tubular damage and albuminuria were ameliorated and expression of ACE2, AT2R and Mas and activity of ACE2 were increased, effects associated with reduced ERK1/2 phosphorylation, decreased fibrosis and renal protection. Ultra-high doses did not influence the ACE2/AT2R/Mas axis and promoted renal injury with increased renal ERK1/2 activation and exaggerated fibronectin expression in db/db mice. Our study demonstrates dose-related effects of candesartan in diabetic nephropathy: intermediate–high dose candesartan is renoprotective, whereas ultra-high dose candesartan induces renal damage. Molecular processes associated with these effects involve differential modulation of the ACE2/AT2R/Mas axis: intermediate–high dose candesartan up-regulating RAS protective components and attenuating pro-fibrotic processes, and ultra-high doses having opposite effects. These findings suggest novel mechanisms through the protective RAS axis, whereby candesartan may ameliorate diabetic nephropathy. Our findings also highlight potential injurious renal effects of ultra-high dose candesartan in diabetes.

Low-protein diet supplemented with ketoacids ameliorates proteinuria in 3/4 nephrectomised rats by directly inhibiting the intrarenal renin-angiotensin system

Low-protein diet plus ketoacids (LPD+KA) has been reported to decrease proteinuria in patients with chronic kidney diseases (CKD). However, the mechanisms have not been clarified. As over-activation of intrarenal renin-angiotensin system (RAS) has been shown to play a key role in the progression of CKD, the current study was performed to investigate the direct effects of LPD+KA on intrarenal RAS, independently of renal haemodynamics. In this study, 3/4 subtotal renal ablated rats were fed 18 % normal-protein diet (Nx-NPD), 6 % low-protein diet (Nx-LPD) or 5 % low-protein diet plus 1 % ketoacids (Nx-LPD+KA) for 12 weeks. Sham-operated rats fed NPD served as controls. The level of proteinuria and expression of renin, angiotensin II (AngII) and its type 1 receptors (AT1R) in the renal cortex were markedly higher in Nx-NPD group than in the sham group. LPD+KA significantly decreased the proteinuria and inhibited intrarenal RAS activation. To exclude renal haemodynamic impact on intrarenal RAS, the serum samples derived from the different groups were added to the culture medium of mesangial cells. It showed that the serum from Nx-NPD directly induced higher expression of AngII, AT1R, fibronectin and transforming growth factor-β1 in the mesangial cells than in the control group. Nx-LPD+KA serum significantly inhibited these abnormalities. Then, proteomics and biochemical detection suggested that the mechanisms underlying these beneficial effects of LPD+KA might be amelioration of the nutritional metabolic disorders and oxidative stress. In conclusion, LPD+KA could directly inhibit the intrarenal RAS activation, independently of renal haemodynamics, thus attenuating the proteinuria in CKD rats.

Ruboxistaurin attenuates diabetic nephropathy via modulation of TGF-β1/Smad and GRAP pathways

Objective

To investigate whether ruboxistaurin (a selective PKC-β inhibitor) mediates renoprotective effect via interference with TGF-β1/Smad-GRAP cross-signalling.

Method

Diabetes was induced in rats by a single intraperitoneal injection of streptozotocin (55 mg/kg). Then, the diabetic rats were treated with ruboxistaurin (10 mg/kg, p.o) for 6 weeks. Valsartan (15 mg/kg, p.o) was used as a positive control. After 6 weeks of treatment, diabetic nephropathy biomarkers were assessed. TGF-β1, Smad2, and Smad3 mRNA and protein levels were detected using qPCR and western blot analysis.

Key findings

Data showed that serum creatinine, kidney/body weight ratio and urinary albumin excretion significantly increased in diabetic rats. These changes were significantly attenuated by treatment with ruboxistaurin. A significant up-regulation of TGF-β1, Smad2 and Smad3 mRNA expression was observed in diabetic rats, which was alleviated by administration of ruboxistaurin. Furthermore, immunoblotting showed a significant improvement in protein levels of TGF-β1 (P &lt; 0.01), Smad2/3 (P &lt; 0.01) and p-Smad3 (P &lt; 0.001) in diabetic rats treated with ruboxistaurin compared to untreated. Importantly, the reduction in GRAP protein expression in diabetic kidney was prevented by treatment with ruboxistaurin.

Conclusion

These data suggest that the renoprotective effect of ruboxistaurin is possibly due to down-regulation of TGF-β1/Smad pathway and normalization of GRAP protein expression.

Angiotensin II induces reorganization of the actin cytoskeleton and myosin light-chain phosphorylation in podocytes through rho/ROCK-signaling pathway

AIMS

In the present study, we have evaluated the effect of angiotensin II (Ang II) on actin cytoskeleton reorganization and myosin light-chain (MLC) phosphorylation in podocytes to demonstrate whether the Rho/Rho-associated coiled kinase (ROCK) pathway is involved podocyte injury.

METHODS

Eighteen male Sprague-Dawley rats were divided into three groups and treated with Ang II, saline or telmisartan. Morphological changes were studied at 28 days after treatment. Immunohistochemistry and Western blotting were used to determine the renal expression of p-MLC and ROCK2. Cultured podocytes were treated with Ang II (10(-7 )M) with or without Rho-kinase inhibitor (Y27632, 10(-6 )M) for variable time periods. F-actin was visualized with fluorescein isothiocyanate (FITC)-conjugated phalloidin or tetraethyl rhodamine isothiocyanate (TRITC)-conjugated phalloidin. p-MLC expression was evaluated by immunofluorescence and Western blot. The activation of Rho/ROCK was evaluated by Western blot.

RESULTS

The expression of p-MLC in glomeruli increased significantly in rats treated with Ang II when compared to the control rats as shown by Western blot (p < 0.05). In cultured podocytes, Rho A and ROCK2 increased after incubation with Ang II. Ang II increased the expression of ROCK2, which was accompanied with altered morphology, redistribution of actin and increased phosphorylation of MLC. The distribution of actin changed to a large extent, although overall quantitative differences were not observed. Addition of Y-27632 to podocytes treated with Ang II could ameliorate F-actin cytoskeleton remodeling and the increment in p-MLC expression.

CONCLUSION

Ang II-induced podocyte cytoskeleton protein expression changing through the RhoA/ROCK2 p-MLC/F-actin pathway.

Proteinuria, but Not eGFR, Predicts Stroke Risk in Chronic Kidney Disease: Chronic Renal Insufficiency Cohort Study

BACKGROUND AND PURPOSE

Chronic kidney disease is associated with an increased risk of cardiovascular events. However, the impact of chronic kidney disease on cerebrovascular disease is less well understood. We hypothesized that renal function severity would be predictive of stroke risk, independent of other vascular risk factors.

METHODS

The study population included 3939 subjects enrolled in the Chronic Renal Insufficiency Cohort (CRIC) study, a prospective observational cohort. Stroke events were reported by participants and adjudicated by 2 vascular neurologists. Cox proportional hazard models were used to compare measures of baseline renal function with stroke events. Multivariable analysis was performed to adjust for key covariates.

RESULTS

In 3939 subjects, 143 new stroke events (0.62 events per 100 person-years) occurred over a mean follow-up of 6.4 years. Stroke risk was increased in subjects who had worse baseline measurements of renal function (estimated glomerular filtration rate and total proteinuria or albuminuria). When adjusted for variables known to influence stroke risk, total proteinuria or albuminuria, but not estimated glomerular filtration rate, were associated with an increased risk of stroke. Treatment with blockers of the renin-angiotensin system did not decrease stroke risk in individuals with albuminuria.

CONCLUSIONS

Proteinuria and albuminuria are better predictors of stroke risk in patients with chronic kidney disease than estimated glomerular filtration rate. The impact of therapies targeting proteinuria/albuminuria in individuals with chronic kidney disease on stroke prevention warrants further investigation.

Proteomic urinary biomarker approach in renal disease: from discovery to implementation

Biomarkers hold the promise of significantly improving health care by enabling prognosis and diagnosis with improved accuracy, and at earlier points in time. Previous results have indicated that single biomarkers are not suitable to describe complex diseases such as kidney disease. Here we provide an update on the progress of urinary proteomics-based studies and strategies to develop biomarker-based classifiers that tolerate instability and inconsistency of individual biomarkers. The examples focus on two major fields in nephrology: chronic kidney disease in the adult population and obstructive nephropathies in the pediatric population. When employed adequately, urinary proteomics demonstrates a clear value in kidney disease, indicating that the current status quo ruling for decades now could be changed by applying modern "omics" approaches. However, while research is able to deliver these useful tools for patient management, the issues associated with implementation are not yet solved. Active engagement of the relevant clinical professional societies, as well as patient's organizations, might help to implement these omics approaches that have shown a clear benefit for the patient.

Blood pressure goals and treatment in pregnant patients with chronic kidney disease

As the age of pregnant women and prevalence of obesity and diabetes are increasing, so is the prevalence of medical disorders during pregnancy, particularly hypertension and the associated CKD. Pregnancy can worsen kidney function in women with severe disease, and hypertension puts them at risk for pre-eclampsia and the associated complications. There are no specific guidelines for hypertension management in this population, and tight control will not prevent pre-eclampsia. Women with end-stage kidney disease should be placed on intense dialysis regimens to improve obstetric outcomes, and angiotensin-converting enzyme inhibitors and angiotensin receptor blockers are best avoided. This article will review the rationale for a management plan that includes a multidisciplinary team to discuss risks and develop a plan before conception, antepartum monitoring for maternal and fetal morbidity, individualization of medical management using medications with established records during pregnancy, and balancing the level of blood pressure control proved to protect kidney function against the potential effects that aggressive blood pressure control could have on the fetal-placental unit.

Basic fibroblast growth factor reduces functional and structural damage in chronic kidney disease

Chronic kidney disease (CKD) is characterized by loss of renal function. The pathological processes involved in the progression of this condition are already known, but the molecular mechanisms have not been completely explained. Recent reports have shown the intrinsic capacity of the kidney to undergo repair after acute injury through the reexpression of repairing proteins (Villanueva S, Cespedes C, Vio CP. Am J Physiol Regul Integr Comp Physiol 290: R861-R870, 2006). Stimulation with basic fibroblast growth factor (bFGF) could accelerate this process. However, it is not known whether bFGF can induce this phenomenon in kidney cells affected by CKD. Our aim was to study the evolution of renal damage in animals with CKD treated with bFGF and to relate the amount of repairing proteins with renal damage progression. Male Sprague-Dawley rats were subjected to 5/6 nephrectomy (NPX) and treated with bFGF (30 μg/kg, NPX+bFGF); a control NPX group was treated with saline (NPX+S). Animals were euthanized 35 days after bFGF administration. Functional effects were assessed based on serum creatinine levels; morphological damage was assessed by the presence of macrophages (ED-1), interstitial α-smooth muscle actin (α-SMA), and interstitial collagen through Sirius red staining. The angiogenic factors VEGF and Tie-2 and the epithelial/tubular factors Ncam, bFGF, Pax-2, bone morphogenic protein-7, Noggin, Lim-1, Wnt-4, and Smads were analyzed. Renal stem cells were evaluated by Oct-4. We observed a significant reduction in serum creatinine levels, ED-1, α-SMA, and Sirius red as well as an important induction of Oct-4, angiogenic factors, and repairing proteins in NPX+bFGF animals compared with NPX+S animals. These results open new perspectives toward reducing damage progression in CKD.

Impaired endocytosis in proximal tubule from subchronic exposure to cadmium involves angiotensin II type 1 and cubilin receptors

BACKGROUND

Chronic exposure to low cadmium (Cd) levels produces urinary excretion of low molecular weight proteins, which is considered the critical effect of Cd exposure. However, the mechanisms involved in Cd-induced proteinuria are not entirely clear. Therefore, the present study was designed to evaluate the possible role of megalin and cubilin (important endocytic receptors in proximal tubule cells) and angiotensin II type 1 (AT1) receptor on Cd-induced microalbuminuria.

METHODS

Four groups of female Wistar rats were studied. Control (CT) group, vehicle-treated rats; LOS group, rats treated with losartan (an AT1 antagonist) from weeks 5 to 8 (10 mg/kg/day by gavage); Cd group, rats subchronically exposed to Cd (3 mg/kg/day by gavage) during 8 weeks, and Cd + LOS group, rats treated with Cd for 8 weeks and LOS from weeks 5-8. Kidney Cd content, glomerular function (evaluated by creatinine clearance and plasma creatinine), kidney injury and tubular function (evaluated by Kim-1 expression, urinary excretion of N-acetyl-β-D-glucosaminidase (NAG) and glucose, and microalbuminuria), oxidative stress (measured by lipid peroxidation and NAD(P)H oxidase activity), mRNA levels of megalin, expressions of megalin and cubilin (by confocal microscopy) and AT1 receptor (by Western blot), were measured in the different experimental groups. Data were analyzed by one-way ANOVA or Kruskal-Wallis test using GraphPad Prism 5 software (Version 5.00). P < 0.05 was considered statistically significant.

RESULTS

Administration of Cd (Cd and Cd + LOS groups) increased renal Cd content. LOS-treatment decreased Cd-induced microalbuminuria without changes in: plasma creatinine, creatinine clearance, urinary NAG and glucose, oxidative stress, mRNA levels of megalin and cubilin, neither protein expression of megalin nor AT1 receptor, in the different experimental groups studied. However, Cd exposure did induce the expression of the tubular injury marker Kim-1 and decreased cubilin protein levels in proximal tubule cells whereas LOS-treatment restored cubilin levels and suppressed Kim-1 expression.

CONCLUSION

LOS treatment decreased microalbuminuria induced by Cd apparently through a cubilin receptor-dependent mechanism but independent of megalin.

Addition of aliskiren to Angiotensin receptor blocker improves ambulatory blood pressure profile and cardiorenal function better than addition of benazepril in chronic kidney disease

An altered ambulatory blood pressure (BP) and heart rate (HR) profile is related to chronic kidney disease (CKD) and cardiorenal syndrome. In this study, we examined the effects of aliskiren, when added to angiotensin II type 1 receptor blockers, on ambulatory BP and cardiorenal function in CKD. Thirty-six hypertensive CKD patients were randomly assigned to the aliskiren add-on group (n = 18) or the benazepril add-on group (n = 18). Ambulatory BP and cardiorenal function parameters were measured at baseline and 24 weeks after treatment. Compared with the benazepril group, nighttime systolic BP variability in the aliskiren group was lower after treatment. Albuminuria was decreased in the aliskiren group, but not in the benazepril group. In addition, left ventricular mass index (LVMI) was significantly lower in the aliskiren group than in the benazepril group after treatment. In the aliskiren group, multivariate linear regression analysis showed an association between changes in albuminuria and changes in nighttime systolic BP. Furthermore, there were associations between changes in LVMI and changes in daytime HR variability, as well as between changes in LVMI and changes in plasma aldosterone concentration. These results suggest that aliskiren add-on therapy may be beneficial for suppression of renal deterioration and pathological cardiac remodeling through an improvement that is effected in ambulatory BP and HR profiles.

Sirtuins and renal diseases: relationship with aging and diabetic nephropathy

Sirtuins are members of the Sir2 (silent information regulator 2) family, a group of class III deacetylases. Mammals have seven different sirtuins, SIRT1-SIRT7. Among them, SIRT1, SIRT3 and SIRT6 are induced by calorie restriction conditions and are considered anti-aging molecules. SIRT1 has been the most extensively studied. SIRT1 deacetylates target proteins using the coenzyme NAD+ and is therefore linked to cellular energy metabolism and the redox state through multiple signalling and survival pathways. SIRT1 deficiency under various stress conditions, such as metabolic or oxidative stress or hypoxia, is implicated in the pathophysiologies of age-related diseases including diabetes, cardiovascular diseases, neurodegenerative disorders and renal diseases. In the kidneys, SIRT1 may inhibit renal cell apoptosis, inflammation and fibrosis, and may regulate lipid metabolism, autophagy, blood pressure and sodium balance. Therefore the activation of SIRT1 in the kidney may be a new therapeutic target to increase resistance to many causal factors in the development of renal diseases, including diabetic nephropathy. In addition, SIRT3 and SIRT6 are implicated in age-related disorders or longevity. In the present review, we discuss the protective functions of sirtuins and the association of sirtuins with the pathophysiology of renal diseases, including diabetic nephropathy.

The angiotensin II type 1 receptor blocker olmesartan preferentially improves nocturnal hypertension and proteinuria in chronic kidney disease

Accumulated evidence suggests that an altered ambulatory blood pressure (BP) profile, particularly elevated nighttime BP, reflects target organ injury and is a better predictor of further cardiorenal risk than the clinic BP or daytime BP in hypertensive patients complicated by chronic kidney disease (CKD). In this study, we examined the beneficial effects of olmesartan, an angiotensin II type 1 receptor blocker (ARB), on ambulatory BP profiles and renal function in hypertensive CKD patients. Forty-six patients were randomly assigned to the olmesartan add-on group (n=23) or the non-ARB group (n=23). At baseline and after the 16-week treatment period, ambulatory BP monitoring was performed and renal function parameter measurements were collected. Although the baseline clinic BP levels and the after-treatment/baseline (A/B) ratios of clinic BP levels were similar in the olmesartan add-on and non-ARB groups, the A/B ratios of ambulatory 24-h and nighttime BP levels in the olmesartan add-on group were significantly lower. Furthermore, the A/B ratios of urinary protein, albumin and type IV collagen excretion in the olmesartan add-on group were significantly lower than those in the non-ARB group (urinary protein excretion, 0.72±0.41 vs. 1.45±1.48, P=0.030; urinary albumin excretion, 0.73±0.37 vs. 1.50±1.37, P=0.005; urinary type IV collagen excretion, 0.87±0.42 vs. 1.48±0.87, P=0.014) despite comparable A/B ratios for the estimated glomerular filtration rate in the two groups. These results indicate that in hypertensive patients with CKD, olmesartan add-on therapy improves the ambulatory BP profile via a preferential reduction in nighttime BP with concomitant renal injury inhibition.

Impact of AT2 receptor deficiency on postnatal cardiovascular development

BACKGROUND

The angiotensin II receptor subtype 2 (AT2 receptor) is ubiquitously and highly expressed in early postnatal life. However, its role in postnatal cardiac development remained unclear.

METHODOLOGY/PRINCIPAL FINDINGS

Hearts from 1, 7, 14 and 56 days old wild-type (WT) and AT2 receptor-deficient (KO) mice were extracted for histomorphometrical analysis as well as analysis of cardiac signaling and gene expression. Furthermore, heart and body weights of examined animals were recorded and echocardiographic analysis of cardiac function as well as telemetric blood pressure measurements were performed. Moreover, gene expression, sarcomere shortening and calcium transients were examined in ventricular cardiomyocytes isolated from both genotypes. KO mice exhibited an accelerated body weight gain and a reduced heart to body weight ratio as compared to WT mice in the postnatal period. However, in adult KO mice the heart to body weight ratio was significantly increased most likely due to elevated systemic blood pressure. At postnatal day 7 ventricular capillarization index and the density of α-smooth muscle cell actin-positive blood vessels were higher in KO mice as compared to WT mice but normalized during adolescence. Echocardiographic assessment of cardiac systolic function at postnatal day 7 revealed decreased contractility of KO hearts in response to beta-adrenergic stimulation. Moreover, cardiomyocytes from KO mice showed a decreased sarcomere shortening and an increased peak Ca(2+) transient in response to isoprenaline when stimulated concomitantly with angiotensin II.

CONCLUSION

The AT2 receptor affects postnatal cardiac growth possibly via reducing body weight gain and systemic blood pressure. Moreover, it moderately attenuates postnatal vascularization of the heart and modulates the beta adrenergic response of the neonatal heart. These AT2 receptor-mediated effects may be implicated in the physiological maturation process of the heart.

Peritoneovenous shunting for refractory ascites results in worsening of nephrotic syndrome

Peritoneovenous shunt (PVS) is accepted as a treatment for refractory ascites due to liver cirrhosis. Infection is a well-known complication of shunting. However, the effects of PVS in terms of complications for renal disease are unclear. We encountered a case involving a 52-year-old man with alcoholic liver cirrhosis and complications of nephrotic syndrome that were worsened by PVS. He received PVS for refractory ascites due to alcoholic liver cirrhosis before coming to our hospital for evaluation for liver transplantation. Nephrotic syndrome was then identified due to cirrhosis-related membranoproliferative glomerulonephritis (MPGN). Prednisolone was administrated at 60 mg/day for MPGN. On day 5, he showed grade IV hepatic encephalopathy (West Haven criteria). Tapering prednisolone and intestinal cleansing with lactulose treatment improved hepatic encephalopathy, but hyperammonemia persisted and the PVS was removed. After shunt removal, urinary protein levels decreased from 4-6 g/day to 0.3-0.5 g/day and ammonia levels decreased. PVS may increase the excretion of urinary protein and increase ammonia levels in patients with complications of glomerulonephritis.

Progress in pathogenesis of proteinuria

Aims. Proteinuria not only is a sign of kidney damage, but also is involved in the progression of renal diseases as an independent pathologic factor. Clinically, glomerular proteinuria is most commonly observed, which relates to structural and functional anomalies in the glomerular filtration barrier. The aim of this paper was to describe the pathogenesis of glomerular proteinuria. Data Sources. Articles on glomerular proteinuria retrieved from Pubmed and MEDLINE in the recent 5 years were reviewed. Results. The new understanding of the roles of glomerular endothelial cells and the glomerular basement membrane (GBM) in the pathogenesis of glomerular proteinuria was gained. The close relationships of slit diaphragm (SD) molecules such as nephrin, podocin, CD2-associated protein (CD2AP), a-actinin-4, transient receptor potential cation channel 6 (TRPC6), Densin and membrane-associated guanylate kinase inverted 1 (MAGI-1), α3β1 integrin, WT1, phospholipase C epsilon-1 (PLCE1), Lmx1b, and MYH9, and mitochondrial disorders and circulating factors in the pathogenesis of glomerular proteinuria were also gradually discovered. Conclusion. Renal proteinuria is a manifestation of glomerular filtration barrier dysfunction. Not only glomerular endothelial cells and GBM, but also the glomerular podocytes and their SDs play an important role in the pathogenesis of glomerular proteinuria.

Clinical features and outcomes of 98 children and adults with dense deposit disease

BACKGROUND

Dense deposit disease (DDD) is an ultra-rare renal disease.

METHODS

In the study reported here, 98 patients and their families participated in a descriptive patient-centered survey using an online research format. Reports were completed by patients (38%) or their parents (62%). Age at diagnosis ranged from 1.9 to 38.9 years (mean 14 years).

RESULTS

The majority of patients presented with proteinuria and hematuria; 50% had hypertension and edema. Steroids were commonly prescribed, although their use was not evidence-based. One-half of the patients with DDD for 10 years progressed to end-stage renal disease (ESRD), with young females having the greatest risk for renal failure. Of first allografts, 45% failed within 5 years, most frequently due to recurrent disease (70%). Type 1 diabetes (T1D) was present in over 16% of families, which represents a 116-fold increase in incidence compared with the general population (p < 0.001).

CONCLUSIONS

Based on these findings, we suggest that initiatives are needed to explore the high incidence of T1D in family members of DDD patients and the greater risk for progression to ESRD in young females with DDD. These efforts must be supported by sufficient numbers of patients to establish evidence-based practice guidelines for disease management. An international collaborative research survey should be implemented to encourage broad access and participation.

Losartan protects mesenteric arteries from ROS-associated decrease in myogenic constriction following 5/6 nephrectomy

BACKGROUND

Chronic renal failure (CRF) is associated with hypertension, proteinuria, loss of myogenic constriction (MC) of mesenteric arteries and increased production of reactive oxygen species (ROS) under experimental conditions. Previous results showed that ACE (angiotensin-converting enzyme activity) inhibitor therapy is effective in slowing down the progression of disease. Therefore, we wanted to study whether the inverse AT(1) (angiotensin II type 1) receptor agonist, losartan (LOS) was effective in preventing loss of MC in a rat model of CRF and whether acute ROS scavengers could improve MC.

METHODS

Rats underwent 5/6 nephrectomy (5/6 Nx) and were treated with vehicle or LOS (20 mg/kg/day; 5/6 Nx + LOS) for 12 weeks. Thereafter, the MC of the mesenteric arteries were measured in the presence and/or absence of tempol and catalase. Systolic blood pressure and proteinuria were measured weekly.

RESULTS

Systolic blood pressure and proteinuria in the 5/6 Nx + LOS group were significantly lower than in the 5/6 Nx group. Moreover, the MC of 5/6 Nx + LOS arteries was significantly increased compared with the untreated 5/6 Nx group (maximum MC, 32.3 ± 6.9 vs 8.9 ± 3.8% (p < 0.01)). Tempol + catalase significantly increased the MC in the 5/6 Nx group, but not in the 5/6 Nx + LOS group (increase in MC, 59.7 ± 13.0 (p < 0.05) vs. 17.0 ± 15.1%).

CONCLUSION

These results support the roles of the RAAS (renin-angiotensin-aldosterone system) and ROS in the vascular dysfunction of systemic vessels in CRF.

Is the reno-protective effect of valsartan dose dependent? A comparative study of 80 and 160 mg day(-1)

Whether the reno-protective effect of angiotensin receptor blockers is dose dependent is unknown for the Japanese population. We sought to elucidate the dose-dependent reno-protective effects of valsartan in Japanese hypertensive patients with albuminuria. This was a multi-center, open-label, parallel-group trial. A total of 181 patients were randomized to receive either 80 (n=89) or 160 mg day(-1) (n=92) of valsartan for 24 weeks. Then, the effects on blood pressure, urinary albumin excretion (UAE), type IV collagen and beta(2)-microglobulin (beta2MG) were determined. Systolic and diastolic blood pressures decreased substantially by almost the same extent in the low-dose and high-dose groups, showing no inter-group difference during the treatment. The UAE value decreased significantly by 35% in both groups. Urinary excretion of beta2MG was significantly decreased in the high-dose group (17%), but not in the low-dose group (13%), although the decrease was not significantly different between the two groups (P=0.74). Urinary excretion of type IV collagen decreased non-significantly by 10% in the low-dose group and by 8% in the high-dose group, showing no significant inter-group difference (P=0.78). Low (80 mg day(-1)) and high (160 mg day(-1)) doses of valsartan showed a similar effect of lowering blood pressure. The high dose of valsartan resulted in a slightly greater decrease in urinary beta2MG, but it was inconclusive whether the high dose was more reno-protective as compared with the low dose.

Effects of angiotensin II type 1 receptor blocker on ambulatory blood pressure variability in hypertensive patients with overt diabetic nephropathy

Previous studies have shown increases in ambulatory short-term blood pressure (BP) variability to be related to cardiovascular disease. In this study, we examined whether the angiotensin II type 1 receptor blocker (ARB) would improve ambulatory short-term BP variability in hypertensive patients with diabetic nephropathy. A total of 30 patients with type II diabetes, along with hypertension and overt nephropathy, were enrolled in this randomized, two-period, crossover trial of 12 weeks of treatment with losartan (50 mg daily) and telmisartan (40 mg daily). At baseline and at the end of each treatment period, 24-h ambulatory BP monitoring with power spectral analysis of heart rate and measurements of proteinuria, estimated glomerular filtration rate and brachial-ankle pulse wave velocity (baPWV) were performed. After 12 weeks of treatment, 24-h, daytime and nighttime short-term BP variability, assessed on the basis of the coefficient of variation of ambulatory BP, was significantly decreased by telmisartan. Both losartan and telmisartan reduced urinary protein excretion and baPWV. However, compared with losartan, telmisartan significantly decreased urinary protein excretion, baPWV and low-frequency (LF)-to-high-frequency (HF) ratio, an index of sympathovagal balance. Multiple regression analysis showed significant correlations between urinary protein excretion and baPWV, 24-h LF-to-HF ratio, nighttime systolic BP and 24-h short-term systolic BP variability. These results suggest that ARB, particularly telmisartan, is effective in reducing proteinuria in hypertensive patients with overt diabetic nephropathy, partly through inhibitory effects on ambulatory short-term BP variability and sympathetic nerve activity, in addition to its longer duration of action on nighttime BP reduction.

Dopamine D1 receptor (DRD1) genetic polymorphism: pleiotropic effects on heritable renal traits

Because dopamine D(1) receptors (DRD1) influence renal sodium transport and vascular hemodynamics, we examined whether genetic polymorphisms play a role in renal function. We conducted polymorphism discovery across the DRD1 open reading frame and its 5'-UTR and then performed association studies with estimated glomerular filtration rate (eGFR), plasma creatinine (pCr), and fractional excretion of uric acid (FeUA). We used a twin/family group of 428 subjects from 195 families and a replication cohort of 677 patients from the Kaiser health-care organization sampled from the lower percentiles of diastolic blood pressures. Although the coding region lacked common non-synonymous variants, we identified two polymorphisms in the DRD1 5'-UTR (G-94A, A-48G) that occurred with frequencies of 15 and 30%, respectively. In the twin/family study, renal traits were highly heritable, such that DRD1 G-94A significantly associated with eGFR, pCr, and FeUA. Homozygotes for the G-94A minor allele (A/A) exhibited lower eGFR, higher pCr, and lower FeUA. No effects were noted for DRD1 A-48G. Patients in the Kaiser group had similar effects of G-94A on eGFR and pCr. Kidney cells transfected with the -94A variant but not the wild type vectors had increased receptor density. Because the -94A allele is common and may reduce glomerular capillary hydrostatic pressure, G-94A profiling may aid in predicting survival of renal function in patients with progressive renal disease.

Losartan chemistry and its effects via AT1 mechanisms in the kidney

Besides the importance of the renin-angiotensin system (RAS) in the circulation and other organs, the local RAS in the kidney has attracted a great attention in research in last decades. The renal RAS plays an important role in the body fluid homeostasis and long-term cardiovascular regulation. All major components and key enzymes for the establishment of a local RAS as well as two important angiotensin II (Ang II) receptor subtypes, AT1 and AT2 receptors, have been confirmed in the kidney. In additional to renal contribution to the systemic RAS, the intrarenal RAS plays a critical role in the regulation of renal function as well as in the development of kidney disease. Notably, kidney AT1 receptors locating at different cells and compartments inside the kidney are important for normal renal physiological functions and abnormal pathophysiological processes. This mini-review focuses on: 1) the local renal RAS and its receptors, particularly the AT1 receptor and its mechanisms in physiological and pathophysiological processes; and 2) the chemistry of the selective AT1 receptor blocker, losartan, and the potential mechanisms for its actions in the renal RAS-mediated disease.