Effect of tolvaptan on renal handling of water and sodium, GFR and central hemodynamics in autosomal dominant polycystic kidney disease during inhibition of the nitric oxide system: a randomized, placebo-controlled, double blind, crossover study

Notch3 as a novel therapeutic target for the treatment of ADPKD by regulating cell proliferation and renal cyst development

Autosomal dominant polycystic kidney disease (ADPKD) is a common monogenic kidney disease. Emerging research indicates that the Notch signaling pathway plays an indispensable role in the pathogenesis of numerous kidney diseases, including ADPKD. Herein, we identified that Notch3 but not other Notch receptors was overexpressed in renal tissues from mice with ADPKD and ADPKD patients. Inhibiting Notch3 with γ-secretase inhibitors, which block a proteolytic cleavage required for Notch3 activation, or shRNA knockdown of Notch3 significantly delayed renal cyst growth in vitro and in vivo. Subsequent mechanistic study elucidated that the cleaved intracellular domain of Notch3 (N3ICD) and Hes1 could bind to the PTEN promoter, leading to transcriptional inhibition of PTEN. This further activated the downstream PI3K-AKT-mTOR pathway and promoted renal epithelial cell proliferation. Overall, Notch3 was identified as a novel contributor to renal epithelial cell proliferation and cystogenesis in ADPKD. We envision that Notch3 represents a promising target for ADPKD treatment.

Identifying the main predictors of urine output in autosomal-dominant polycystic kidney disease (ADPKD) patients taking tolvaptan

BACKGROUND

Few works have analyzed factors associated with urine output in ADPKD patients taking tolvaptan (TVP).

METHODS

We selected 24-h urine samples from ADPKD patients treated with TVP. Urine osmolality/creatinine ratio was used as estimator of urinary osmolar load.

RESULTS

We included 127 urine samples from 61 patients. After TVP, urine output doubled with a parallel reduction in urine solute concentration. However, when expressed as urine solute/creatinine ratios, no significant changes were observed. Daily osmolar load and osmolality/creatinine ratio did not change significantly. Before TVP, urine output was positively correlated with body weight and urine osmolality/creatinine ratio and negatively with eGFR, urine morning osmolality, and 24-h urine-calculated osmolality. After TVP, urine output was positively correlated with body weight, eGFR and negatively with age. There was a poor correlation with urine-calculated osmolality. We constructed a predictor model using mixed-effects modeling and we found that urine output was related to lower age, higher body weight, higher eGFR, and greater doses of TVP. When body weight was removed, urine output was also related to male sex and a higher daily osmolar excretion. Equation of prediction was: Urine output (mL/day) = 2771-52.9 × Age (years) + 58.4 × Weight (kg) + 18.7 × eGFR (mL/min) + 870 (if TVP = 90/30 mg) + 517 (if TVP = 60/30 mg).

CONCLUSION

Patients taking TVP will undergo an increase about twice in urine production from baseline. Greater doses of TVP cause a progressive increase in urine production. GFR, age, and body weight are the main predictors of future urine output in patients taking TVP.

The efficacy of tolvaptan for heart failure in chronic kidney disease: A protocol for systematic review and meta-analysis

BACKGROUND

Approximately half of people with heart failure have chronic kidney disease (CKD). Tolvaptan is reported to be effective in treating heart failure. However, the safety and efficacy of its use in patients with CKD is uncertain. In this study, we conducted a protocol for systematic review and meta-analysis to investigate the efficacy and safety of tolvaptan on patients with heart failure and CKD.

METHODS

This study protocol has been registered in the PROSPERO and the registration number is CRD42022368148. The consent of this protocol report is based on the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) 2015 statement guidelines. We will include randomized controlled trials related to tolvaptan in patients with heart failure and CKD. Two research members will electronically and independently search 4 English databases (EMBASE, PubMed, National Guideline Clearinghouse, and Cochrane Central Register of Controlled Trials) and 4 Chinese databases (Chinese Biomedical Literature Database, Chinese National Knowledge Infrastructure, Wanfang Database, and VIP Database) from their inception to November 2022. The risk of bias in each included study will be assessed utilizing the Cochrane Collaboration's risk of bias tool. All statistical analyses will be conducted using the software program Review Manager version 5.3.

RESULTS

The results of this systematic review will be published in a peer-reviewed journal.

CONCLUSION

This review can provide convincing evidence to help clinicians make decisions when dealing with heart failure and CKD.

A Systematic Review of Reported Outcomes in ADPKD Studies

Introduction

Methods

Results

Conclusion

Beneficial effects of procyanidin B2 on adriamycin-induced nephrotic syndrome mice: the multi-action mechanism for ameliorating glomerular permselectivity injury

Despite considerable advances in prevention, diagnosis, and therapy, nephrotic syndrome (NS) remains a significant cause of high morbidity and mortality globally. As a result, there is an urgent need to identify novel effective preventative and therapeutic agents for NS. NS is implicated in glomerular permselectivity injury, which can be attributed to oxidative distress, inflammation, lipid nephrotoxicity, podocyte apoptosis, autophagy dysfunction, and slit diaphragm (SLD) dysfunction. In addition to its well-documented antioxidant potency, procyanidin B2 (PB2) may exhibit pleiotropic effects by targeting various canonical signaling events, such as NF-κB, PPARs, PI3K/Akt, mTOR, and the caspase family. As a result, PB2 may be a promising therapeutic target against NS. To test this hypothesis, we established an Adriamycin (ADR)-induced NS mouse model to evaluate the pleiotropic renoprotective effects of PB2 on NS. Here, we demonstrated that PB2 improves podocyte injury via inhibition of NOX4/ROS and Hsp90/NF-κB to exhibit antioxidant and anti-inflammatory potency, respectively. We also show that PB2 indirectly activates the PI3K/Akt axis by regulating SLD protein levels, resulting in normalized podocyte apoptosis and autophagy function. Further, loss of albumin (ALB) induces lipid nephrotoxicity, which we found to be alleviated by PB2 via activation of PPARα/β-mediated lipid homeostasis and the cholesterol efflux axis. Interestingly, our results also suggested that PB2 reduces electrolyte abnormalities and edema. In addition, PB2 may contribute protective effects against trace element dys-homeostasis, which, through alleviating serum ALB loss, leads to a protective effect on glomerular permselectivity injury. Taken together, our results reveal that the identified mechanisms of PB2 on NS are multifactorial and involve inhibition of oxidative distress and inflammatory responses, as well as improvements in podocyte apoptosis and autophagy dysfunction, amelioration of lipid nephrotoxicity, and modulation of electrolyte abnormalities and edema. Thus, we provide a theoretical basis for the clinical application of PB2 against NS.

The Effect of Tolvaptan on BP in Polycystic Kidney Disease: A Post Hoc Analysis of the TEMPO 3:4 Trial

BACKGROUND

The V2 receptor antagonist tolvaptan is prescribed to patients with autosomal dominant polycystic kidney disease to slow disease progression. Tolvaptan may alter BP via various acute and chronic effects.

METHODS

To investigate the magnitude and time course of the effect of tolvaptan use on BP, we conducted a post hoc study of the TEMPO 3:4 trial, which included 1445 patients with autosomal dominant polycystic kidney disease randomized 2:1 to tolvaptan or placebo for 3 years. We evaluated systolic and diastolic BP, mean arterial pressure, hypertension status, and use and dosing of antihypertensive drugs over the course of the trial.

RESULTS

At baseline, BP did not differ between study arms. After 3 weeks of tolvaptan use, mean body weight had decreased from 79.7 to 78.8 kg, and mean plasma sodium increased from 140.4 to 142.6 mmol/L (both P<0.001), suggesting a decrease in circulating volume. We observed none of these changes in the placebo arm. Nonetheless, BP remained similar in the study arms. After 3 years of treatment, however, mean systolic BP was significantly lower in participants receiving tolvaptan versus placebo (126 versus 129 mm Hg, respectively; P=0.002), as was mean diastolic BP (81.2 versus 82.6 mm Hg, respectively; P=0.01). These differences leveled off at follow-up 3 weeks after discontinuation of the study medication. Use of antihypertensive drugs remained similar in both study arms during the entire study.

CONCLUSIONS

Long-term treatment with tolvaptan gradually lowered BP compared with placebo, which may be attributed to a beneficial effect on disease progression, a continued natriuretic effect, or both.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

TEMPO 3:4, NCT00428948.

Effectiveness of Tolvaptan in the Treatment for Patients with Autosomal Dominant Polycystic Kidney Disease: A Meta-analysis

AIMS AND OBJECTIVE

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is a common chronic kidney disease that leads to End-Stage Renal Disease (ESRD). The key target of this therapy is to prevent the progression of kidney failure. Tolvaptan could slow kidney cyst growth and are proven highly effective. The aims of this analysis are to perform a systematic review, estimate and evaluate the efficacy and safety of tolvaptan in ADPKD patients.

MATERIALS AND METHODS

Randomized controlled trials of tolvaptan in ADPKD were identified in PubMed, Ovid, Web of Science and the Cochrane Library electronic database. The changes observed in kidney function, treatment efficiency and the incidence of adverse events between the tolvaptan and placebo groups were compared. Data were analyzed by the RevMan software.

RESULTS

Eight trials, including 7 double-blinded randomised controlled trials and 1 quasi RCT involving 1,536 patients were extracted. Significant differences in the annual rate of change in the total kidney volume TKV at any stages of CKD (MD = -3.32, 95%CI =-4.57,-2.07, I2 =70%) and the glomerular filtration rate (MD = 1.4, 95%CI = 0.83,1.97, I2 =0%) were observed between the tolvaptan group and the placebo group. Subgroup analysis of patients in different CKD stages also showed the same conclusion. There was an increase in the urine osmolality, and 24-hour urine volume in patients receiving tolvaptan. Tolvaptan reduced the rate of serious hypertension and kidney pain events in ADPKD patients. At higher doses, it increased the rate of adverse events (liver injuries, thirst, pollakiuria, and nocturia). There was no significant risk of bias in the included studies.

CONCLUSION

Tolvaptan has a beneficial effect on ADPKD, but is associated with an increase in adverse events at high doses when compared with the placebo. Further RCTs on tolvaptan may be required to support this conclusion.

Effect of furosemide on body composition and urinary proteins that mediate tubular sodium and sodium transport-A randomized controlled trial

Background

Furosemide inhibits the sodium potassium chloride cotransporter (NKCC2) in the thick ascending limb of the loop of Henle and increases urinary water and sodium excretion. This study investigates the effect of furosemide on body composition estimated with multifrequency bioimpedance spectroscopy (BIS) technique and urinary proteins from NKCC2.

Methods

This study is a randomized, placebo‐controlled, crossover study where healthy subjects received either placebo or 40 mg furosemide on two separate occasions, where body composition with BIS, renal function, proteins from tubular proteins that mediate sodium and water transport, and plasma concentrations of vasoactive hormones were measured before and after intervention.

Results

We observed an expected increased diuresis with a subsequent reduction in bodyweight of (−1.51 ± 0.36 kg, p < .001) and extracellular water (ECW; −1.14 ± 0.23 L, p < .001) after furosemide. We found a positive correlation between the decrease in ECW and a decrease in bodyweight and a negative correlation between the decrease in ECW and the increase in urinary output. Intracellular water (ICW) increased (0.47 ± 0.28 L, p < .001). Urinary excretion of NKCC2 increased after furosemide and the increase in NKCC2 correlated with an increase in urine output and a decrease in ECW.

Conclusion

We found BIS can detect acute changes in body water content but the method may be limited to estimation of ECW. BIS demonstrated that furosemide increases ICW which might be explained by an extracellular sodium loss. Finally, urinary proteins from NKCC2 increases after furosemide with a good correlation with diuresis end the decrease in ECW.

A Comparison of Urine Dilution Ability between Adult Dominant Polycystic Kidney Disease, Other Chronic Kidney Diseases, and Healthy Control Subjects: A Case-Control Study

The final dilution of urine is regulated via aquaporin-2 water channels in the distal part of the nephron. It is unclear whether urine dilution ability in autosomal dominant polycystic kidney disease patients (ADPKD patients) differs from other patients with similar degree of impaired renal function (non-ADPKD patients). The purpose of this case control study was to measure urine dilution ability in ADPKD patients compared to non-ADPKD patients and healthy controls. Methods. Eighteen ADPKD, 16 non-ADPKD patients (both with chronic kidney disease, stage I-IV), and 18 healthy controls received an oral water load of 20 ml/kg body weight. Urine was collected in 7 consecutive periods. We measured free water clearance (C_H2O), urine osmolality, urine output, fractional excretion of sodium, urine aquaporin2 (u-AQP2), and urine epithelial sodium channel (u-ENaC). Blood samples were drawn four times (at baseline, 2 h, 4 h, and 6 hours after the water load) for analyses of plasma osmolality, vasopressin, renin, angiotensin II, and aldosterone. Brachial and central blood pressure was measured regularly during the test. Results. The three groups were age and gender matched, and the patient groups had similar renal function. One hour after water load, the ADPKD patients had an increased C_H2O compared to non-ADPKD patients (2.97 ± 2.42 ml/min in ADPKD patients vs. 1.31 ± 1.50 ml/min in non-ADPKD patients, p0.029). The reduction in u-AQP2 and u-ENaC occurred earlier in ADPKD than in non-ADPKD patients. Plasma concentrations of vasopressin, renin, angiotensin II, and aldosterone and blood pressure measurements did not show any differences that could explain the deviation in urine dilution capacity between the patient groups. Conclusions. ADPKD patients had a higher C_H2O than non-ADPKD patients after an oral water load, and u-AQP2 and u-ENaC were more rapidly reduced than in non-ADPKD patients. Thus, urine-diluting capacity may be better preserved in ADPKD patients than in non-ADPKD patients.

Urine concentration ability is reduced to the same degree in adult dominant polycystic kidney disease compared with other chronic kidney diseases in the same CKD-stage and lower THAN in healthy control subjects - a CASE control study

Background

Concentration of the urine is primarily regulated via vasopressin dependent aquaporin-2 water channels in the apical membrane of kidney principal cells. It is unclear whether urine concentration ability in ADPKD differs from other patients with similar degree of impaired renal function (non-ADPKD patients). The purpose of this case control study was to measure urine concentration ability in ADPKD patients compared to non-ADPKD patients and healthy controls.

Methods

A seventeen hour long water deprivation test was carried out in 17 ADPKD patients (CKD I-IV), 16 non-ADPKD patients (CKD I-IV), and 18 healthy controls. Urine was collected in 4 consecutive periods during water deprivation (12 h, 1 h, 2 h and 2 h, respectively) and analyzed for osmolality (u-Osm), output (UO), fractional excretion of sodium (FE_Na), aquaporin2 (u-AQP2) and ENaC (u-ENaC). Blood samples were drawn trice (after 13-, 15-, and 17 h after water deprivation) for analyses of osmolality (p-Osm), vasopressin (p-AVP), and aldosterone (p-Aldo).

Results

U-Osm was significantly lower and FE_Na significantly higher in both ADPKD patients and non-ADPKD patients compared to healthy controls during the last three periods of water deprivation. During the same periods, UO was higher and secretion rates of u-AQP2 and u-ENaC were lower and at the same level in the two groups of patients compared to controls. P-AVP and p-Osm did not differ significantly between the three groups. P-Aldo was higher in both groups of patients than in controls.

Conclusions

Urine concentration ability was reduced to the same extent in patients with ADPKD and other chronic kidney diseases with the same level of renal function compared to healthy controls. The lower urine excretion of AQP2 and ENaC suggests that the underlying mechanism may be a reduced tubular response to vasopressin and aldosterone.

Trial registration

Current Controlled Trial NCT04363554, date of registration: 20.08.2017.

Nocturnal blood pressure decrease in patients with chronic kidney disease and in healthy controls - significance of obstructive sleep apnea and renal function

Background

Chronic kidney disease (CKD) is often associated with a blunted nocturnal BP decrease and OSA. However, it is not fully clear whether a relationship exists between reduction in renal function and obstructive sleep apnea (OSA) on the one hand and relative nocturnal BP decrease in CKD patients on the other. The aim of this study was to investigate the association between nocturnal BP decrease and renal function, the degree of OSA, vasoactive hormones, and renal sodium handling in CKD3-4 patients and healthy age-matched controls.

Methods

We performed brachial and central 24-hour ambulatory BP measurement and CRM in 70 CKD3-4 patients and 56 controls. In plasma, we measured renin, AngII, aldosterone, and vasopressin. In urine, 24-hour excretion of sodium, protein fractions from the epithelial sodium channel (u-ENaCγ), and the AQP2 water channels (u-AQP2) were measured.

Results

CKD patients had lower relative nocturnal BP decrease than controls: brachial (10% vs 17%, P=0.001) and central (6% vs 10%, P=0.001). Moderate-to-severe OSA was more frequent in patients (15 vs 1%, P<0.0001). Neither the presence of OSA nor eGFR were predictors of either brachial or central nocturnal BP decrease. CKD3-4 nondippers were more obese, had higher HbA1c level, and more often a history of acute myocardial infarction than CKD3-4 dippers (P<0.05).

Conclusion

CKD3-4 patients had lower brachial and central nocturnal BP decrease than healthy controls. OSA and eGFR were not associated with nondipping in CKD patients or healthy controls. Nondipping in CKD3-4 was associated with obesity, diabetes, and cardiovascular disease.

ClinicalTrials.gov ID

NCT01951196.

The effect of sodium nitrite infusion on renal function, brachial and central blood pressure during enzyme inhibition by allopurinol, enalapril or acetazolamide in healthy subjects: a randomized, double-blinded, placebo-controlled, crossover study

Background

Sodium nitrite (NaNO₂) causes vasodilation, presumably by enzymatic conversion to nitric oxide (NO). Several enzymes with nitrite reducing capabilities have been discovered in vitro, but their relative importance in vivo has not been investigated. We aimed to examine the effects of NaNO₂ on blood pressure, fractional sodium excretion (FE_Na), free water clearance (C_H2O) and GFR, after pre-inhibition of xanthine oxidase, carbonic anhydrase, and angiotensin-converting enzyme. The latter as an approach to upregulate endothelial NO synthase activity.

Methods

In a double-blinded, placebo-controlled, crossover study, 16 healthy subjects were treated, in a randomized order, with placebo, allopurinol 150 mg twice daily (TD), enalapril 5 mg TD, or acetazolamide 250 mg TD. After 4 days of treatment and standardized diet, the subjects were examined at our lab. During intravenous infusion of 240 μg NaNO₂/kg/hour for 2 h, we measured changes in brachial and central blood pressure (BP), plasma cyclic guanosine monophosphate (P-cGMP), plasma and urine osmolality, GFR by ⁵¹Cr-EDTA clearance, FE_Na and urinary excretion rate of cGMP (U-cGMP) and nitrite and nitrate (U-NO_x). Subjects were supine and orally water-loaded throughout the examination day.

Results

Irrespective of pretreatment, we observed an increase in FE_Na, heart rate, U-NO_x, and a decrease in C_H2O and brachial systolic BP during NaNO₂ infusion. P-cGMP and U-cGMP did not change during infusion. We observed a consistent trend towards a reduction in central systolic BP, which was only significant after allopurinol.

Conclusion

This study showed a robust BP lowering, natriuretic and anti-aquaretic effect of intravenous NaNO₂ regardless of preceding enzyme inhibition. None of the three enzyme inhibitors used convincingly modified the pharmacological effects of NaNO₂. The steady cGMP indicates little or no conversion of nitrite to NO. Thus the effect of NaNO₂ may not be mediated by NO generation.

Trial registration

EU Clinical Trials Register, 2013-003404-39. Registered December 3 2013.