Renal replacement therapy for autosomal dominant polycystic kidney disease (ADPKD) in Europe: prevalence and survival--an analysis of data from the ERA-EDTA Registry

Chronic endothelial dopamine receptor stimulation improves endothelial function and hemodynamics in autosomal dominant polycystic kidney disease

Altered polycystin-mediated endothelial flow mechanosensitivity contributes to the development of hypertension and cardiovascular complications in patients with autosomal dominant polycystic kidney disease (ADPKD). Stimulation of endothelial type 5 dopamine receptors (DR5) can acutely compensate for the endothelial consequences of polycystin deficiency, but the chronic impact of this approach must be evaluated in ADPKD. Nineteen patients with ADPKD on standard of care therapy were randomized to receive a 2-month treatment with the DR agonist rotigotine using transdermal patches, nine at 2 mg/24hours and ten at 4 mg/24hours or while ten were untreated. Rotigotine at the dose of 4 mg/24hours significantly increased nitric oxide release (nitrite levels from 10±30 to 46±34 nmol/L) and radial artery endothelium-dependent flow-mediated dilatation (from 16.4±6.3 to 22.5±7.3%) in response to hand skin heating. Systemic hemodynamics were not significantly modified but aplanation tonometry showed that rotigotine at 4 mg/24hours reduced aortic augmentation index and pulse pressure without affecting carotid-to femoral pulse wave velocity. Plasma creatinine and urea, urinary cyclic AMP, which contributes to cyst growth in ADPKD and copeptin, a surrogate marker of vasopressin, were not affected by rotigotine. In mice with a specific deletion of polycystin-1 in endothelial cells, chronic infusion of the peripheral DR5 agonist fenoldopam also improved mesenteric artery flow-mediated dilatation and reduced blood pressure. Thus, our study demonstrates that in patients with ADPKD, chronic administration of rotigotine improves conduit artery endothelial function through the restoration of flow-induced nitric oxide release as well as hemodynamics suggesting that endothelial DR5 activation may represent a promising pharmacological approach to prevent cardiovascular complications of ADPKD.

Kidney transplantation in patients with polycystic kidney disease: increased risk of infection does not compromise graft and patient survival

Background

Patients with autosomal dominant polycystic kidney disease (ADPKD) represent >10% of patients awaiting kidney transplantation. These patients are prone to potentially severe urinary tract (UTI) and liver cyst infections after transplantation. Whether such infections compromise outcome is unclear.

Methods

Between 2000 and 2017 we performed 193 kidney transplantations in patients with ADPKD. In 189 patients, we assessed the occurrence, frequency, and severity of infection episodes requiring inpatient treatment and their impact on graft and patient outcomes compared with 189 matched controls. Risk factors were analyzed by uni- and multivariable analyses.

Results

During a mean observation period of 77 months UTIs occurred more frequently in ADPKD patients (39.1% vs. 26.7%, P = .022; 0.8 ± 1.4 vs. 0.5 ± 1.1 episodes, P < .001). Eight ADPKD patients suffered from 19 episodes of liver cyst infection. Steroid medication (RR 3.04; P < .001) and recipient age (RR 1.05; P = .003) increased the risk for UTI/urosepsis, while nephrectomy reduced it (unilateral, RR 0.60; P = .088; bilateral, RR 0.45; P = .020). Patient survival was similar in both groups. The risk of graft failure was lower in ADPKD patients [hazard ratio (HR) 0.67; P = .047] due to a lower risk of death-censored graft loss (HR 0.47; P = .014). Donor age (HR 1.34; P = .002) and rejection (HR 8.47; P < .001) were risk factors for death-censored graft loss.

Conclusions

ADPKD patients are at increased risk of UTI and liver cyst infection after transplantation. Steroid medication and recipient age seem to increase the risk of UTI/urosepsis, while nephrectomy seems to reduce it. Nevertheless, patient survival was similar compared to non-ADPKD patients and death-censored graft survival even better.

Perspectives of Patients and Clinicians on Reproductive Health Care and ADPKD

Introduction

Family planning and reproductive care are essential but complex aspects of lifecycle management for individuals with autosomal dominant polycystic kidney disease (ADPKD), given the potential genetic transmission and pregnancy-related complications. In this qualitative study, we studied the experiences and perspectives of patients with ADPKD and clinicians to identify areas for potential improvement in reproductive lifecycle care.

Methods

Focus group discussions (FGDs) were conducted in the Netherlands with patients with ADPKD, both men and women, who had children through varied reproductive choices; and clinicians, including (pediatric) nephrologists, obstetric gynecologists and geneticists. Thematic analysis, utilizing a grounded theory approach, was performed on verbatim transcriptions of recordings, followed by consensus discussions to finalize themes.

Results

Nine focus groups involving 31 participants (16 patients and 15 physicians) identified 6 key themes. These included the need for timely and comprehensive information dissemination from puberty on, understanding patient-specific decision-making factors, improving tailored psychosocial guidance and communication, the need for systematic efforts to take care of missed (minor) at-risk patients, addressing inequities in access to care, and improving multidisciplinary collaboration.

Conclusions

This study represents the first qualitative study of patient and physician perspectives on reproductive lifecycle care for ADPKD. We present valuable insights into factors influencing patients' reproductive decision-making, a comprehensive comparison between the perspectives of patients and clinicians on family planning and follow-up care of minors at risk for ADPKD, and recommendations for enhancing overall care quality. Incorporating these insights into clinical care could enhance patient-centered care and foster interdisciplinary collaborations to further improve the quality of reproductive health care services for individuals with ADPKD.

Quantitative susceptibility mapping for detection of kidney stones, hemorrhage differentiation, and cyst classification in ADPKD

BACKGROUND AND PURPOSE

The objective is to demonstrate feasibility of quantitative susceptibility mapping (QSM) in autosomal dominant polycystic kidney disease (ADPKD) patients and to compare imaging findings with traditional T1/T2w magnetic resonance imaging (MRI).

METHODS

Thirty-three consecutive patients (11 male, 22 female) diagnosed with ADPKD were initially selected. QSM images were reconstructed from the multiecho gradient echo data and compared to co-registered T2w, T1w, and CT images. Complex cysts were identified and classified into distinct subclasses based on their imaging features. Prevalence of each subclass was estimated.

RESULTS

QSM visualized two renal calcifications measuring 9 and 10 mm and three pelvic phleboliths measuring 2 mm but missed 24 calcifications measuring 1 mm or less and 1 larger calcification at the edge of the field of view. A total of 121 complex T1 hyperintense/T2 hypointense renal cysts were detected. 52 (43%) Cysts appeared hyperintense on QSM consistent with hemorrhage; 60 (49%) cysts were isointense with respect to simple cysts and normal kidney parenchyma, while the remaining 9 (7%) were hypointense. The presentation of the latter two complex cyst subtypes is likely indicative of proteinaceous composition without hemorrhage.

CONCLUSION

Our results indicate that QSM of ADPKD kidneys is possible and uniquely suited to detect large renal calculi without ionizing radiation and able to identify properties of complex cysts unattainable with traditional approaches.

Native nephrectomy in polycystic kidney disease patients on transplant lists: how and when?

Autosomal dominant polycystic kidney disease (ADPKD), the most common hereditary kidney disease, accounts for approximately 10% of the patients on kidney transplantation waitlists. High rates of complications including hemorrhage, infections, nephrolithiasis and kidney size-related compressive complaints have been reported among ADPKD patients. Therefore, the need for routine native nephrectomy and timing of such procedure in ADPKD patients being prepared for transplantation are debated. Even though pre-transplant nephrectomy has the potential to provide fewer infectious complications due to lack of immunosuppressive medication use, such procedure has been associated with longer hospital stay, loss of residual kidney function and need for dialysis. Although simultaneous nephrectomy and transplantation could potentially lead to longer perioperative duration, perioperative complications and need for blood transfusions, this was not confirmed in cohort studies. Therefore, some institutions routinely perform simultaneous unilateral nephrectomy and kidney transplantation. In this narrative review, our aim is to evaluate the current evidence regarding the need and timing of nephrectomy in ADPKD patients in relation to kidney transplantation.

Peritoneal dialysis versus haemodialysis for people commencing dialysis

BACKGROUND

Peritoneal dialysis (PD) and haemodialysis (HD) are two possible modalities for people with kidney failure commencing dialysis. Only a few randomised controlled trials (RCTs) have evaluated PD versus HD. The benefits and harms of the two modalities remain uncertain. This review includes both RCTs and non-randomised studies of interventions (NRSIs).

OBJECTIVES

To evaluate the benefits and harms of PD, compared to HD, in people with kidney failure initiating dialysis.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies from 2000 to June 2024 using search terms relevant to this review. Studies in the Register were identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Registry Platform (ICTRP) Search Portal, and ClinicalTrials.gov. MEDLINE and EMBASE were searched for NRSIs from 2000 until 28 March 2023.

SELECTION CRITERIA

RCTs and NRSIs evaluating PD compared to HD in people initiating dialysis were eligible.

DATA COLLECTION AND ANALYSIS

Two investigators independently assessed if the studies were eligible and then extracted data. Risk of bias was assessed using standard Cochrane methods, and relevant outcomes were extracted for each report. The primary outcome was residual kidney function (RKF). Secondary outcomes included all-cause, cardiovascular and infection-related death, infection, cardiovascular disease, hospitalisation, technique survival, life participation and fatigue.

MAIN RESULTS

A total of 153 reports of 84 studies (2 RCTs, 82 NRSIs) were included. Studies varied widely in design (small single-centre studies to international registry analyses) and in the included populations (broad inclusion criteria versus restricted to more specific participants). Additionally, treatment delivery (e.g. automated versus continuous ambulatory PD, HD with catheter versus arteriovenous fistula or graft, in-centre versus home HD) and duration of follow-up varied widely. The two included RCTs were deemed to be at high risk of bias in terms of blinding participants and personnel and blinding outcome assessment for outcomes pertaining to quality of life. However, most other criteria were assessed as low risk of bias for both studies. Although the risk of bias (Newcastle-Ottawa Scale) was generally low for most NRSIs, studies were at risk of selection bias and residual confounding due to the constraints of the observational study design. In children, there may be little or no difference between HD and PD on all-cause death (6 studies, 5752 participants: RR 0.81, 95% CI 0.62 to 1.07; I2 = 28%; low certainty) and cardiovascular death (3 studies, 7073 participants: RR 1.23, 95% CI 0.58 to 2.59; I2 = 29%; low certainty), and was unclear for infection-related death (4 studies, 7451 participants: RR 0.98, 95% CI 0.39 to 2.46; I2 = 56%; very low certainty). In adults, compared with HD, PD had an uncertain effect on RKF (mL/min/1.73 m2) at six months (2 studies, 146 participants: MD 0.90, 95% CI 0.23 to 3.60; I2 = 82%; very low certainty), 12 months (3 studies, 606 participants: MD 1.21, 95% CI -0.01 to 2.43; I2 = 81%; very low certainty) and 24 months (3 studies, 334 participants: MD 0.71, 95% CI -0.02 to 1.48; I2 = 72%; very low certainty). PD had uncertain effects on residual urine volume at 12 months (3 studies, 253 participants: MD 344.10 mL/day, 95% CI 168.70 to 519.49; I2 = 69%; very low certainty). PD may reduce the risk of RKF loss (3 studies, 2834 participants: RR 0.55, 95% CI 0.44 to 0.68; I2 = 17%; low certainty). Compared with HD, PD had uncertain effects on all-cause death (42 studies, 700,093 participants: RR 0.87, 95% CI 0.77 to 0.98; I2 = 99%; very low certainty). In an analysis restricted to RCTs, PD may reduce the risk of all-cause death (2 studies, 1120 participants: RR 0.53, 95% CI 0.32 to 0.86; I2 = 0%; moderate certainty). PD had uncertain effects on both cardiovascular (21 studies, 68,492 participants: RR 0.96, 95% CI 0.78 to 1.19; I2 = 92%) and infection-related death (17 studies, 116,333 participants: RR 0.90, 95% CI 0.57 to 1.42; I2 = 98%) (both very low certainty). Compared with HD, PD had uncertain effects on the number of patients experiencing bacteraemia/bloodstream infection (2 studies, 2582 participants: RR 0.34, 95% CI 0.10 to 1.18; I2 = 68%) and the number of patients experiencing infection episodes (3 studies, 277 participants: RR 1.23, 95% CI 0.93 to 1.62; I2 = 20%) (both very low certainty). PD may reduce the number of bacteraemia/bloodstream infection episodes (2 studies, 2637 participants: RR 0.44, 95% CI 0.27 to 0.71; I2 = 24%; low certainty). Compared with HD; It is uncertain whether PD reduces the risk of acute myocardial infarction (4 studies, 110,850 participants: RR 0.90, 95% CI 0.74 to 1.10; I2 = 55%), coronary artery disease (3 studies, 5826 participants: RR 0.95, 95% CI 0.46 to 1.97; I2 = 62%); ischaemic heart disease (2 studies, 58,374 participants: RR 0.86, 95% CI 0.57 to 1.28; I2 = 95%), congestive heart failure (3 studies, 49,511 participants: RR 1.10, 95% CI 0.54 to 2.21; I2 = 89%) and stroke (4 studies, 102,542 participants: RR 0.94, 95% CI 0.90 to 0.99; I2 = 0%) because of low to very low certainty evidence. Compared with HD, PD had uncertain effects on the number of patients experiencing hospitalisation (4 studies, 3282 participants: RR 0.90, 95% CI 0.62 to 1.30; I2 = 97%) and all-cause hospitalisation events (4 studies, 42,582 participants: RR 1.02, 95% CI 0.81 to 1.29; I2 = 91%) (very low certainty). None of the included studies reported specifically on life participation or fatigue. However, two studies evaluated employment. Compared with HD, PD had uncertain effects on employment at one year (2 studies, 593 participants: RR 0.83, 95% CI 0.20 to 3.43; I2 = 97%; very low certainty).

AUTHORS' CONCLUSIONS

The comparative effectiveness of PD and HD on the preservation of RKF, all-cause and cause-specific death risk, the incidence of bacteraemia, other vascular complications (e.g. stroke, cardiovascular events) and patient-reported outcomes (e.g. life participation and fatigue) are uncertain, based on data obtained mostly from NRSIs, as only two RCTs were included.

Vascular Access Outcomes in Patients with Autosomal Dominant Polycystic Kidney Disease

Key Points

More patients with autosomal dominant polycystic kidney disease received their first intervention to re-establish vascular access patency. Patients with autosomal dominant polycystic kidney disease do not require differential monitoring and treatment of hemodialysis vascular access.

Background

Autosomal dominant polycystic kidney disease (ADPKD) is a leading hereditary cause of ESKD, often using hemodialysis as a form of RRT. Patients with ADPKD may also present with extrarenal manifestations, including arterial aneurysms. The gold standard for hemodialysis access is an arteriovenous vascular access (VA), such as arteriovenous fistulas (AVFs) or arteriovenous grafts (AVGs). However, limitations, such as low VA flow and inadequate AVF outward remodeling, affect VA utilization. This study aimed to explore whether ADPKD affects patency rates of AVFs/AVGs in comparison with other underlying ESKD causes.

Methods

We conducted a retrospective cohort study using data from the Swedish Renal Registry from 2011 to 2020, with follow-up until 2022. We included 496 patients with ADPKD and 4321 propensity score–matched controls. VA patency rates of patients with ADPKD were compared with those of non-ADPKD patients using Kaplan–Meier survival curves and Mantel–Cox log-rank test. Interventions to maintain or restore patency were also analyzed.

Results

Patients with ADPKD constituted 8.0% of all patients, with a higher proportion in the pre-ESKD phase during VA creation (51.6% versus 40.6%). No significant differences were observed in primary, postcannulation primary, secondary, or functional patency between patients with ADPKD and non-ADPKD patients. However, more VAs were ligated in patients with ADPKD (10.5% versus 7.7%, P = 0.03), and they underwent more first interventions to re-establish flow (49.4% versus 41.9%, P = 0.02).

Conclusions

These findings suggest that AVF/AVG patency remains comparable in patients with ESKD with or without ADPKD, and VA monitoring and treatment strategies for patients with ADPKD should align with those for individuals with other ESKD causes.

Computational drug discovery approaches identify mebendazole as a candidate treatment for autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is a rare genetic disorder characterised by numerous renal cysts, the progressive expansion of which can impact kidney function and lead eventually to renal failure. Tolvaptan is the only disease-modifying drug approved for the treatment of ADPKD, however its poor side effect and safety profile necessitates the need for the development of new therapeutics in this area. Using a combination of transcriptomic and machine learning computational drug discovery tools, we predicted that a number of existing drugs could have utility in the treatment of ADPKD, and subsequently validated several of these drug predictions in established models of disease. We determined that the anthelmintic mebendazole was a potent anti-cystic agent in human cellular and in vivo models of ADPKD, and is likely acting through the inhibition of microtubule polymerisation and protein kinase activity. These findings demonstrate the utility of combining computational approaches to identify and understand potential new treatments for traditionally underserved rare diseases.

How Does ADPKD Severity Differ Between Family Members?

Thousands of pathogenic variants in more than 100 genes can cause kidney cysts with substantial variability in phenotype and risk of subsequent kidney failure. Despite an established genotype-phenotype correlation in cystic kidney diseases, incomplete penetrance and variable disease expressivity are present as is the case in all monogenic diseases. In family members with autosomal dominant polycystic kidney disease (ADPKD), the same causal variant is responsible in all affected family members; however, there can still be striking discordance in phenotype severity. This narrative review explores contributors to within-family discordance in ADPKD severity. Cases of biallelic and digenic inheritance, where 2 rare pathogenic variants in cystogenic genes are coexistent in one family, account for a small proportion of within-family discordance. Genetic background, including cis and trans factors and the polygenic propensity for comorbid disease, also plays a role but has not yet been exhaustively quantified. Environmental exposures, including diet; smoking; alcohol, salt, and protein intake, and comorbid diseases, including obesity, diabetes, hypertension, kidney stones, dyslipidemia, and additional coexistent kidney diseases all contribute to ADPKD phenotypic variability among family members. Given that many of the factors contributing to phenotype variability are preventable, modifiable, or treatable, health care providers and patients need to be aware of these factors and address them in the treatment of ADPKD.

The screening, diagnosis, and management of patients with autosomal dominant polycystic kidney disease: A national consensus statement from Taiwan

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited cause of end-stage kidney disease (ESKD) worldwide. Guidelines for the diagnosis and management of ADPKD in Taiwan remains unavailable. In this consensus statement, we summarize updated information on clinical features of international and domestic patients with ADPKD, followed by suggestions for optimal diagnosis and care in Taiwan. Specifically, counselling for at-risk minors and reproductive issues can be important, including ethical dilemmas surrounding prenatal diagnosis and pre-implantation genetic diagnosis. Studies reveal that ADPKD typically remains asymptomatic until the fourth decade of life, with symptoms resulting from cystic expansion with visceral compression, or rupture. The diagnosis can be made based on a detailed family history, followed by imaging studies (ultrasound, computed tomography, or magnetic resonance imaging). Genetic testing is reserved for atypical cases mostly. Common tools for prognosis prediction include total kidney volume, Mayo classification and PROPKD/genetic score. Screening and management of complications such as hypertension, proteinuria, urological infections, intracranial aneurysms, are also crucial for improving outcome. We suggest that the optimal management strategies of patients with ADPKD include general medical care, dietary recommendations and ADPKD-specific treatments. Key points include rigorous blood pressure control, dietary sodium restriction and Tolvaptan use, whereas the evidence for somatostatin analogues and mammalian target of rapamycin (mTOR) inhibitors remains limited. In summary, we outline an individualized care plan emphasizing careful monitoring of disease progression and highlight the need for shared decision-making among these patients.

Initial eGFR Changes Predict Response to Tolvaptan in ADPKD

Key Points

This post hoc analysis of the Tolvaptan Efficacy and Safety in Management of Autosomal Dominant Polycystic Kidney Disease and Its Outcomes 3:4 study investigated the long-term predictive potential of initial changes in eGFR. Initial eGFR change from baseline to week 3 proved to be a significant and independent indicator of the long-term effects of tolvaptan. No correlation was found between the initial change in eGFR and the annual rate of percent growth in total kidney volume.

Background

Tolvaptan, the only pharmaceutical treatment available for autosomal dominant polycystic kidney disease (ADPKD), reduced the rates of total kidney volume (TKV) increase and kidney function decline in patients with ADPKD in the global phase 3 Tolvaptan Efficacy and Safety in Management of Autosomal Dominant Polycystic Kidney Disease and Its Outcomes (TEMPO) 3:4 study. Since tolvaptan initiation is associated with an initial decline in the eGFR, this post hoc analysis of the TEMPO 3:4 study investigated whether initial changes in eGFR from baseline to week 3 after tolvaptan administration can predict its longer-term effects on eGFR and TKV in patients with ADPKD.

Methods

eGFR was estimated using the CKD Epidemiology Collaboration equation at baseline and up to month 36. TKV was estimated using standardized kidney magnetic resonance imaging at baseline and after 12, 24, and 36 months of tolvaptan treatment. The effect of tolvaptan on kidney function and kidney volume was evaluated by measuring changes in eGFR from week 3 and TKV from baseline up to 36 months. All 961 patients randomized to receive tolvaptan in TEMPO 3:4 were included in this analysis.

Results

Initial change in eGFR from baseline to week 3 was a significant and independent predictor of the mean rate of change in eGFR per year. By contrast, there was no association between initial change in eGFR and the rate of percent growth in TKV per year.

Conclusions

Changes in eGFR after 3 weeks of treatment are likely due to the pharmacologic effect of tolvaptan, and these initial changes are predictive of the long-term effects of tolvaptan treatment.

Effects of salt and protein intake on polyuria in V2RA-treated ADPKD patients

BACKGROUND

The only treatment proven to be renoprotective in autosomal dominant polycystic kidney disease (ADPKD) is a vasopressin V2-receptor antagonist (V2RA). However, aquaresis-associated side effects limit tolerability. We investigated whether salt and/or protein intake influences urine volume and related endpoints in V2RA-treated ADPKD patients.

METHODS

In this randomized, controlled, double-blind, crossover trial, ADPKD patients treated with maximally tolerated dose of a V2RA were included. While on a low salt and low protein diet, patients were given additional salt and protein to mimic regular intake, which was subsequently replaced by placebo in random order during four 2-week periods. Primary endpoint was change in 24-h urine volume. Secondary endpoints were change in quality of life, measured glomerular filtration rate (mGFR), blood pressure and copeptin level.

RESULTS

Twelve patients (49 ± 8 years, 25.0% male) were included. Baseline salt and protein intake were 10.8 ± 1.3 g/24-h and 1.2 ± 0.2 g/kg/24-h, respectively. During the low salt and low protein treatment periods, intake decreased to 5.8 ± 1.6 g/24-h and 0.8 ± 0.1 g/kg/24-h, respectively. Baseline 24-h urine volume (5.9 ± 1.2 L) decreased to 5.2 ± 1.1 L (-11%, P = .004) on low salt and low protein, and to 5.4 ± 0.9 L (-8%, P = .04) on low salt. Reduction in 24-h urine volume was two times greater in patients with lower urine osmolality (-16% vs -7%). Polyuria quality of life scores improved in concordance with changes in urine volume. mGFR decreased during the low salt and low protein, while mean arterial pressure did not change during study periods. Plasma copeptin decreased significantly during low salt and low protein periods.

CONCLUSION

Lowering dietary salt and protein intake has a minor effect on urine volume in V2RA-treated ADPKD patients. Reduced intake of osmoles decreased copeptin concentrations and might thus increase the renoprotective effect of a V2RA in ADPKD patients.

Exploring the impact and utility of genomic sequencing in established CKD

Clinical genetics is increasingly recognized as an important area within nephrology care. Clinicians require awareness of genetic kidney disease to recognize clinical phenotypes, consider use of genomics to aid diagnosis, and inform treatment decisions. Understanding the broad spectrum of clinical phenotypes and principles of genomic sequencing is becoming increasingly required in clinical nephrology, with nephrologists requiring education and support to achieve meaningful patient outcomes. Establishment of effective clinical resources, multi-disciplinary teams and education is important to increase application of genomics in clinical care, for the benefit of patients and their families. Novel applications of genomics in chronic kidney disease include pharmacogenomics and clinical translation of polygenic risk scores. This review explores established and emerging impacts and utility of genomics in kidney disease.

The Han:SPRD Rat: A Preclinical Model of Polycystic Kidney Disease

Autosomal Dominant Polycystic Kidney Disease (ADPKD) stands as the most prevalent hereditary renal disorder in humans, ultimately culminating in end-stage kidney disease. Animal models carrying mutations associated with polycystic kidney disease have played an important role in the advancement of ADPKD research. The Han:SPRD rat model, carrying an R823W mutation in the Anks6 gene, is characterized by cyst formation and kidney enlargement. The mutated protein, named Samcystin, is localized in cilia of tubular epithelial cells and seems to be involved in cystogenesis. The homozygous Anks6 mutation leads to end-stage renal disease and death, making it a critical factor in kidney development and function. This review explores the utility of the Han:SPRD rat model, highlighting its phenotypic similarity to human ADPKD. Specifically, we discuss its role in preclinical trials and its importance for investigating the pathogenesis of the disease and developing new therapeutic approaches.

State of the Science and Ethical Considerations for Preimplantation Genetic Testing for Monogenic Cystic Kidney Diseases and Ciliopathies

There is a broad phenotypic spectrum of monogenic polycystic kidney diseases (PKDs). These disorders often involve cilia-related genes and lead to the development of fluid-filled cysts and eventual kidney function decline and failure. Preimplantation genetic testing for monogenic (PGT-M) disorders has moved into the clinical realm. It allows prospective parents to avoid passing on heritable diseases to their children, including monogenic PKD. The PGT-M process involves embryo generation through in vitro fertilization, with subsequent testing of embryos and selective transfer of those that do not harbor the specific disease-causing variant(s). There is a growing body of literature supporting the success of PGT-M for autosomal-dominant and autosomal-recessive PKD, although with important technical limitations in some cases. This technology can be applied to many other types of monogenic PKD and ciliopathies despite the lack of existing reports in the literature. PGT-M for monogenic PKD, like other forms of assisted reproductive technology, raises important ethical questions. When considering PGT-M for kidney diseases, as well as the potential to avoid disease in future generations, there are regulatory and ethical considerations. These include limited government regulation and unstandardized consent processes, potential technical errors, high cost and equity concerns, risks associated with pregnancy for mothers with kidney disease, and the impact on all involved in the process, including the children who were made possible with this technology.

Cardiometabolic comorbidities in autosomal dominant polycystic kidney disease: a 16-year retrospective cohort study

BACKGROUND

Autosomal-dominant polycystic kidney disease (ADPKD) is the most prevalent hereditary kidney disease and the fourth leading cause of end-stage renal disease (ESRD) requiring renal replacement therapy (RRT). Nevertheless, there is a paucity of epidemiological research examining the risk factors and survival on RRT for ADPKD. Thus, we aimed to investigate the cumulative effects of cardiometabolic comorbidities, including hypertension (HTN), type 2 diabetes mellitus (DM), and dyslipidemia (DLP) to clinical outcomes in ADPKD.

METHODS

We identified 6,142 patients with ADPKD aged ≥ 20 years from 2000 to 2015 using a nationwide population-based database. HTN, DM, and DLP diagnoses before or at the time of ADPKD diagnosis and different combinations of the three diagnoses were used as the predictors for the outcomes. Survival analyses were used to estimate the adjusted mortality risk from cardiometabolic comorbidities and the risk for renal survival.

RESULTS

Patients with ADPKD who developed ESRD had the higher all-cause mortality (HR, 5.14; [95% CI: 3.88-6.80]). Patients with all three of the diseases had a significantly higher risk of entering ESRD (HR:4.15, [95% CI:3.27-5.27]), followed by those with HTN and DM (HR:3.62, [95% CI:2.82-4.65]), HTN and DLP (HR:3.54, [95% CI:2.91-4.31]), and HTN alone (HR:3.10, [95% CI:2.62-3.66]) compared with those without any three cardiometabolic comorbidities.

CONCLUSIONS

Our study discovered the cumulative effect of HTN, DM, and DLP on the risk of developing ESRD, which reinforces the urgency of proactive prevention of cardiometabolic comorbidities to improve renal outcomes and overall survival in ADPKD patients.

Case report: Genotype-phenotype characteristics of nine novel PKD1 mutations in eight Chinese patients with autosomal dominant polycystic kidney disease

Introduction

Autosomal dominant polycystic kidney disease (ADPKD) is a common genetic disorder. The PKD1 gene is responsible for the majority of ADPKD cases, and the mutations in this gene exhibit high genetic diversity. This study aimed to investigate the association between genotype and phenotype in ADPKD patients with PKD1 gene mutations through pedigree analysis.

Methods

Eight Chinese pedigrees affected by ADPKD were analyzed using whole-exome sequencing (WES) on peripheral blood DNA. The identified variants were validated using Sanger sequencing, and clinical data from the patients and their families were collected and analyzed.

Results

Nine novel mutation sites in PKD1 were discovered across the pedigrees, including c.4247T > G, c.3298_3301delGAGT, c.4798A > G, c.7567G > A, c.11717G > C, c.7703 + 5G > C, c.3296G > A, c.8515_8516insG, and c.5524C > A. These mutations were found to be associated with a range of clinical phenotypes, including chronic kidney disease, hypertension, and polycystic liver. The age of onset and disease progression displayed significant heterogeneity among the pedigrees, with some individuals exhibiting early onset and rapid disease progression, while others remained asymptomatic or had milder disease symptoms. Inheritance patterns supported autosomal dominant inheritance, as affected individuals inherited the mutations from affected parents. However, there were instances of individuals carrying the mutations who remained asymptomatic or exhibited milder disease phenotypes.

Conclusion

This study highlights the importance of comprehensive genotype analysis in understanding the progression and prognosis of ADPKD. The identification of novel mutation sites expands our knowledge of PKD1 gene mutations. These findings contribute to a better understanding of the disease and may have implications for personalized therapeutic strategies.

Evaluation of advanced imaging biomarkers at kidney failure in patients with ADPKD: a pilot study

Background

Autosomal dominant polycystic kidney disease (ADPKD) presents with variable disease severity and progression. Advanced imaging biomarkers may provide insights into cystic and non-cystic processes leading to kidney failure in different age groups.

Methods

This pilot study included 39 ADPKD patients with kidney failure, stratified into three age groups (<46, 46-56, >56 years old). Advanced imaging biomarkers were assessed using an automated instance cyst segmentation tool. The biomarkers were compared with an age- and sex-matched ADPKD cohort in early chronic kidney disease (CKD).

Results

Ht-total parenchymal volume correlated negatively with age at kidney failure. The median Ht-total parenchymal volume was significantly lower in patients older than 56 years. Cystic burden was significantly higher at time of kidney failure, especially in patients who reached it before age 46 years. The cyst index at kidney failure was comparable across age groups and Mayo Imaging Classes. Advanced imaging biomarkers showed higher correlation with Ht-total kidney volume in early CKD than at kidney failure. Cyst index and parenchymal index were relatively stable over 5 years prior to kidney failure, whereas Ht-total cyst volume and cyst parenchymal surface area increased significantly.

Conclusion

Age-related differences in advanced imaging biomarkers suggest variable pathophysiological mechanisms in ADPKD patients with kidney failure. Further studies are needed to validate the utility of these biomarkers in predicting disease progression and guiding treatment strategies.

An update on absolute and relative indications for dialysis treatment modalities

Background

Choosing a dialysis modality is an important decision for people to make as their kidney failure progresses. In doing so, their options should be informed by any absolute or relative indications that may favour one modality over another.

Methods

In creating this update, we reviewed literature using a framework that considered first, high-level outcomes (survival and modality transition) from large registry data and cohort studies when considering optimal patient pathways; second, factors at a dialysis provider level that might affect relative indications; and third, specific patient-level factors. Both main types of dialysis modality, peritoneal (PD) and haemodialysis (HD), and their subtypes were considered.

Results

For most people starting dialysis, survival is independent of modality, including those with diabetes. Better survival is seen in those with less comorbidity starting with PD or home HD, reflecting continued improvements over recent decades that have been greater than improvements seen for centre HD. There are provider-level differences in the perceived relative indications for home dialysis that appear to reflect variability in experience, prejudice, enthusiasm, and support for patients and carers. Absolute contraindications are uncommon and, in most cases, where modality prejudice exists, e.g. obesity, Adult Polycystic Kidney Disease, and social factors, this is not supported by reported outcomes.

Conclusion

Absolute contraindications to a particular dialysis modality are rare. Relative indications for or against particular modalities should be considered but are rarely more important than patient preferences.

Dialysis and Transplant Considerations in Autosomal Dominant Polycystic Kidney Disease

Autosomal dominant polycystic kidney disease (ADPKD) is the fourth leading cause of kidney replacement therapy. Unfortunately, the need for dialysis or kidney transplantation is a foreseeable outcome for many patients affected by ADPKD. We review some of the unique issues that should be considered in the management of patients with ADPKD who require dialysis or kidney transplantation. The choice of dialysis modality may be influenced by the enlarged kidneys and liver, but peritoneal dialysis should not be excluded as an option, as studies do not consistently show that there is an increased risk for technique failure or peritonitis. The optimal kidney replacement therapy option remains kidney transplantation; however, nephrectomy may be needed if there is insufficient space for the allograft. Living donor candidates from at-risk families need to be excluded from carrying the disease either by diagnostic imaging criteria or genetic testing. Other potential transplant issues, such as malignancy and cardiovascular and metabolic risks, should also be recognized. Despite these issues, patients with ADPKD requiring dialysis or kidney transplantation generally have more favorable outcomes as compared to those with other causes of chronic kidney disease. Further studies are still needed to personalize the therapeutic approach for those receiving kidney replacement therapy and eventually improve clinical outcomes.

Dehydration Accelerates Cytogenesis and Cyst Growth in Pkd1-/- Mice by Regulating Macrophage M2 Polarization

Adult autosomal dominant polycystic kidney disease (ADPKD) has been shown to be related as a "third hit" to the occurrence of acute or chronic kidney injury. Here, we examined whether dehydration, as a common kidney risk factor, could cause cystogenesis in chronic-onset Pkd1-/- mice by regulating macrophage activation. First, we confirmed that dehydration accelerated cytogenesis in Pkd1-/- mice and that macrophages infiltrated the kidney tissues even earlier than macroscopic cyst formation. Then, microarray analysis suggested that glycolysis pathway may be involved in macrophage activation in Pkd1-/- kidneys under conditions of dehydration. Further, we confirmed glycolysis pathway was activated and lactic acid (L-LA) was overproduced in the Pkd1-/- kidney under conditions of dehydration. We have already proved that L-LA strongly stimulated M2 macrophage polarization and overproduction of polyamine in macrophage in vitro, and in the present study, we further discovered that M2 polarization-induced polyamine production shortened the primary cilia length by disrupting the PC1/PC2 complex. Finally, the activation of L-LA-arginase 1-polyamine pathway contributed to cystogenesis and progressive cyst growth in Pkd1-/- mice recurrently exposed to dehydration.

Interaction Between Determinants Governing Urine Volume in Patients With ADPKD on Tolvaptan and its Impact on Quality of Life

Introduction

Autosomal dominant polycystic kidney disease (ADPKD) is the most prevalent genetic cause of kidney failure. Tolvaptan, a vasopressin 2 receptor antagonist, is the first drug with proven disease-modifying activity. Long-term treatment adherence is crucial, but a considerable fraction of patients discontinue treatment, because of aquaretic side effects.

Methods

Twenty-four-hour urine was collected in 75 patients with ADPKD during up-titration of tolvaptan and, in combination with clinical characteristics, examined to identify factors influencing urine volume. Patient-reported outcomes were analyzed using the Short Form-12 (SF-12) and patient-reported outcomes questionnaires reporting micturition frequency and burden of urine volume.

Results

Initiation of therapy led to a large increase in urine volume followed by only minor further increase during up-dosing. Younger patients and patients with better kidney function experienced a larger relative rise. Twenty-four-hour urine osmolality dropped by about 50% after therapy initiation independently of dose, with a considerable proportion of patients achieving adequate suppression. Sodium and potassium intake turned out to be the only significant modifiable factors for urine volume after multivariate linear regression models, whereas age and weight could be identified as non-modifiable factors. No change in quality of life (QoL) was detected in relation to treatment or urine volume using SF-12 questionnaires, a finding that was further supported by the results of the patient-reported outcomes assessment.

Conclusion

This study provides an in-detail analysis of factors associated with the degree of polyuria on tolvaptan and puts them into the context of QoL. These findings will contribute to optimized patient counseling regarding this treatment option in ADPKD.

Autosomal dominant polycystic kidney disease in Colombia

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic cause of chronic kidney disease (CKD) that requires dialysis. Knowing geographical clusters can be critical for early diagnosis, progression control, and genetic counseling. The objective was to establish the prevalence, geographic location, and ethnic groups of patients with ADPKD who underwent dialysis or kidney transplant in Colombia between 2015 and 2019.

METHODS

We did a cross-sectional study with data from the National Registry of Chronic Kidney Disease (NRCKD) managed by the High-Cost Diseases Fund (Cuenta de Alto Costo [CAC] in Spanish) between July 1, 2015, and June 30, 2019. We included Colombian population with CKD with or without renal replacement therapy (RRT) due to ADPKD. Crude and adjusted prevalence rates were estimated by state and city.

RESULTS

3,339 patients with ADPKD were included, period prevalence was 9.81 per 100,000 population; there were 4.35 cases of RRT per 100,000 population, mean age of 52.58 years (± 13.21), and 52.78% women. Seventy-six patients were Afro-Colombians, six were indigenous, and one Roma people. A total of 46.07% began scheduled dialysis. The highest adjusted prevalence rate was in Valle del Cauca (6.55 cases per 100,000 population), followed by Risaralda, and La Guajira. Regarding cities, Cali had the highest prevalence rate (9.38 cases per 100,000 population), followed by Pasto, Medellin, and Bucaramanga.

CONCLUSIONS

ADPKD prevalence is lower compared to Europe and US; some states with higher prevalence could be objective to genetic prevalence study.

Drug Development in Autosomal Dominant Polycystic Kidney Disease: Opportunities and Challenges

Autosomal dominant polycystic kidney disease (ADPKD) is a hereditary disorder characterized by relentless growth of innumerable renal cysts bilaterally, associated with decline in glomerular filtration rate over the course of decades. The burden of ADPKD and its treatment is associated with a significant economic and societal cost. Despite several clinical studies conducted over the past decade, only one treatment has been approved by regulatory agencies to slow disease progression in ADPKD. Elucidating feasible endpoints and clear regulatory pathway may stimulate interest in developing and translating novel therapeutics. This review summarizes the recent progress, challenges, and opportunities in drug development for ADPKD. We discuss the traditional and accelerated regulatory approval pathways, the various clinical trials endpoints, and biomarkers in ADPKD. Furthermore, we propose strategies that could optimize the clinical trial design in ADPKD. Finally, we owe it to our ADPKD patient community to strive for international collaborative studies geared toward discovery and validation of surrogate endpoints and to rally for funded infrastructure that would allow phase 3 master protocols in ADPKD. These advances will serve to derisk and potentially accelerate the development of therapies and eventually bring hope to patients and families who endure through this devastating disease.

The impact of pre-transplantation nephrectomy on quality of life in patients with autosomal dominant polycystic kidney disease

PURPOSE

In selected ADPKD patients, a nephrectomy is required in the work-up for a kidney transplantation. Because the impact of this procedure is unknown, we investigated the effect of pre-transplantation nephrectomy on quality of life in this group.

METHODS

In this retrospective cohort study all ADPKD patients, ≥ 18 years, who received a kidney transplantation in 2 ADPKD expertise centers between January 2000 and January 2016, were asked to participate. Quality of life was assessed using three validated questionnaires on three time points. Nephrectomy was performed in preparation for transplantation.

RESULTS

Two hundred seventy-six ADPKD patients (53 ± 9 years, 56.2% male) were included. 98 patients (35.5%) underwent native nephrectomy in preparation for transplantation, of which 43 underwent bilateral nephrectomy. Pre-transplantation, ADPKD-IS scores were worse in the nephrectomy group vs. no-nephrectomy group (physical: 2.9 vs. 2.3, p < 0.001; emotional: 2.0 vs. 1.8, p = 0.03; fatigue: 3.0 vs. 2.3, p = 0.01). Post-transplantation and post-nephrectomy, ADPKD-IS scores improved significantly in both groups, with a significantly higher improvement in the nephrectomy group. During follow-up, all scores were still better compared to pre-transplantation. Observed physical QoL (ADPKD-IS physical 1.3 vs. 1.7, p = 0.04; SF-36 physical 50.0 vs. 41.3, p = 0.03) was better post-transplantation after bilateral nephrectomy compared to unilateral nephrectomy. In retrospect, 19.7% of patients would have liked to undergo a nephrectomy, while the decision not to perform nephrectomy was made by the treating physician.

CONCLUSION

This study shows that pre-transplantation nephrectomy improves quality of life in selected ADPKD patients. Bilateral nephrectomy may be preferred, although the risk of additional complications should be weighted.

A Low-Cost Sequencing Platform for Rapid Genotyping in ADPKD and its Impact on Clinical Care

Introduction

Autosomal-dominant polycystic kidney disease (ADPKD) is the most common genetic cause of kidney failure. Because of the heterogeneity in disease progression in ADPKD, parameters predicting future outcome are important. The disease-causing genetic variant is one of these parameters.

Methods

A multiplex polymerase chain reaction (PCR)-based panel (MPP) was established for analysis of 6 polycystic kidney disease (PKD) genes (PKD1, PKD2, HNF1B, GANAB, DZIP1L, and PKHD1) in 441 patients with ADPKD. Selected patients were additionally sequenced using Sanger sequencing or a custom enrichment-based gene panel. Results were combined with clinical characteristics to assess the impact of genetic data on clinical decision-making. Variants of unclear significance (VUS) were considered diagnostic based on a classic ADPKD clinical phenotype.

Results

Using the MPP, disease-causing variants were detected in 65.3% of patients. Sanger sequencing and the custom gene panel in 32 patients who were MPP-negative revealed 20 variants missed by MPP, (estimated overall false negative rate 24.6%, false-positive rate 9.4%). Combining clinical and genetic data revealed that knowledge of the genotype could have impacted the treatment decision in 8.2% of patients with a molecular genetic diagnosis. Sequencing only the PKD1 pseudogene homologous region in MPP-negative patients resulted in an acceptable false-negative rate of 3.28%.

Conclusion

The MPP yields rapid genotype information at lower costs and allows for simple extension of the panel for new disease genes. Additional sequencing of the PKD1 pseudogene homologous region is required in negative cases. Access to genotype information even in settings with limited resources is important to allow for optimal patient counseling in ADPKD.

Chronic Kidney Disease: Challenges in Translational Medicine

Chronic kidney disease (CKD) has long been recognized as a state of progressive decline in renal function. Morbidity and mortality are well correlated to the stage of renal function decline. Approximately one million deaths are estimated to be related to CKD worldwide. They are mostly associated with cardiovascular disease as a result of concurrent hypertension, accelerated atherosclerosis, and volume overload. Even with the best current treatment, disease progression is the general rule with a small fraction who reach CKD stage 5 requiring kidney transplantation or dialysis. Transplant patients show substantial reductions in mortality and cardiovascular events, as well as improvements in quality of life. However, the capacity of health systems to deliver kidney transplantation varies worldwide with worse indicators in low-income countries. Consequently, exploring novel and better therapeutic options for CKD is mandatory. Cell-based therapy is a promising strategy for treating CKD in preclinical models, and several clinical trials involving kidney disease exhibit a favorable safety profile. This chapter aims to provide an overview of CKD and the recent results of clinical trials of cell therapy in kidney diseases.

Utility of ultrasonography for predicting indications for tolvaptan in patients with autosomal dominant polycystic kidney disease

PURPOSE

Tolvaptan is the first approved treatment for autosomal dominant polycystic kidney disease (ADPKD) that targets a mechanism directly contributing to the development and growth of renal cysts. We investigated the ability of ultrasonography to predict total kidney volume (TKV) of 750 mL or more, which is an indication for tolvaptan therapy in patients with ADPKD.

METHODS

A total of 46 patients with ADPKD were evaluated. The most statistically appropriate measurement based on ultrasonography for predicting TKV determined by computed tomography (CT) was assessed.

RESULTS

TKV determined by CT was 796.8 (508.8-1,560.3) mL. The median length, anteroposterior distance, and mediolateral distance determined using ultrasonography were 15.7 cm, 7.6 cm, and 7.6 cm in the left kidney, and 13.4 cm, 6.9 cm, and 7.2 cm in the right kidney, respectively. Multivariate regression analysis showed that total kidney length (left and right) [variance inflation factor (VIF), 9.349] and total mediolateral distance (left and right) (VIF, 3.988) were independently associated with TKV. The correlation (r) between the logarithm of TKV determined by CT and total mediolateral distance determined using ultrasonography was 0.915 (p < 0.001). The linear regression equation was log (total kidney volume) = 1.833 + 0.075 × total mediolateral distance (left and right) based on ultrasonography. The area under the receiver operating characteristic curve for total mediolateral distance determined using ultrasonography to predict TKV of 750 mL or more was 0.989. Using the total mediolateral distance cut-off value of 14.2 cm, the sensitivity and specificity were 96.0% and 100.0%, respectively.

CONCLUSION

Total mediolateral distance determined using ultrasonography can predict TKV in patients with ADPKD.

Caspase-1 and the inflammasome promote polycystic kidney disease progression

We and others have previously shown that the presence of renal innate immune cells can promote polycystic kidney disease (PKD) progression. In this study, we examined the influence of the inflammasome, a key part of the innate immune system, on PKD. The inflammasome is a system of molecular sensors, receptors, and scaffolds that responds to stimuli like cellular damage or microbes by activating Caspase-1, and generating critical mediators of the inflammatory milieu, including IL-1β and IL-18. We provide evidence that the inflammasome is primed in PKD, as multiple inflammasome sensors were upregulated in cystic kidneys from human ADPKD patients, as well as in kidneys from both orthologous (PKD1 RC/RC or RC/RC) and non-orthologous (jck) mouse models of PKD. Further, we demonstrate that the inflammasome is activated in female RC/RC mice kidneys, and this activation occurs in renal leukocytes, primarily in CD11c+ cells. Knock-out of Casp1, the gene encoding Caspase-1, in the RC/RC mice significantly restrained cystic disease progression in female mice, implying sex-specific differences in the renal immune environment. RNAseq analysis implicated the promotion of MYC/YAP pathways as a mechanism underlying the pro-cystic effects of the Caspase-1/inflammasome in females. Finally, treatment of RC/RC mice with hydroxychloroquine, a widely used immunomodulatory drug that has been shown to inhibit the inflammasome, protected renal function specifically in females and restrained cyst enlargement in both male and female RC/RC mice. Collectively, these results provide evidence for the first time that the activated Caspase-1/inflammasome promotes cyst expansion and disease progression in PKD, particularly in females. Moreover, the data suggest that this innate immune pathway may be a relevant target for therapy in PKD.

Endothelium-Specific Deficiency of Polycystin-1 Promotes Hypertension and Cardiovascular Disorders

Background:

Autosomal dominant polycystic kidney disease is the most frequent hereditary kidney disease and is generally due to mutations in PKD1 and PKD2 , encoding polycystins 1 and 2. In autosomal dominant polycystic kidney disease, hypertension and cardiovascular disorders are highly prevalent, but their mechanisms are partially understood.

Methods:

Since endothelial cells express the polycystin complex, where it plays a central role in the mechanotransduction of blood flow, we generated a murine model with inducible deletion of Pkd1 in endothelial cells ( Cdh5-Cre ERT2 ; Pkd1 fl/fl ) to specifically determine the role of endothelial polycystin-1 in autosomal dominant polycystic kidney disease.

Results:

Endothelial deletion of Pkd1 induced endothelial dysfunction, as demonstrated by impaired flow-mediated dilatation of resistance arteries and impaired relaxation to acetylcholine, increased blood pressure and prevented the normal development of arteriovenous fistula. In experimental chronic kidney disease induced by subtotal nephrectomy, endothelial deletion of Pkd1 further aggravated endothelial dysfunction, vascular remodeling, and heart hypertrophy.

Conclusions:

Altogether, this study provides the first in vivo demonstration that specific deletion of Pkd1 in endothelial cells promotes endothelial dysfunction and hypertension, impairs arteriovenous fistula development, and potentiates the cardiovascular alterations associated with chronic kidney disease.

Outcomes from the Northeast England cohort of autosomal dominant polycystic kidney disease (ADPKD) patients on tolvaptan

Autosomal dominant polycystic kidney disease (ADPKD) is a cause of end-stage kidney disease (ESKD). The vasopressin V2-receptor antagonist tolvaptan has been shown within randomized clinical trials to slow down decline of kidney function in patients with ADPKD at risk of rapid progression. We performed a retrospective review of a Northeast England cohort of adult ADPKD patients who had been established on tolvaptan therapy to determine its efficacy in a real-world clinic setting. Other inclusion criteria involved a pre-treatment decline in greater than 2.5 ml/min/1.73m2/year based on readings for a 3 year period, and ability to tolerate and maintain tolvaptan treatment for at least 12 months. We calculated based on eGFR slopes, predicted time to reach ESKD with and without tolvaptan therapy. The cohort of patients included 21 from the Northeast of England. The mean rate of eGFR decline prior to treatment was -6.02 ml/min/1.73m2/year for the cohort. Following tolvaptan treatment, the average decline in eGFR was reduced to -2.47 ml/min/1.73m2/year, gaining a mean 8 years and 4 months delay to reach ESKD. The majority of patients (n=19) received and tolerated full dose tolvaptan (90 mg/30 mg). The real-life use of tolvaptan gave a dramatic improvement in eGFR slopes, much more than previously reported in clinical studies. These effects may be in part due to careful patient identification, selection and inclusion of patients who were able to tolerate tolvaptan therapy, excellent compliance with medication and a "tolvaptan clinic" effect where great personal care was given to these patients.

Utilizing the same incision for staged renal transplant in patients with polycystic kidney disease requiring hand-assisted laparoscopic nephrectomy

BACKGROUNDS

Many autosomal dominant polycystic kidney disease (ADPKD) patients undergo nephrectomy and subsequent renal transplantation. We report our outcomes after hand-assisted laparoscopic nephrectomy (HALN) where a Rutherford-Morrison incision is used as a hand-port site and kidney extraction site, as well the future incision site for staged transplantation.

METHODS

A retrospective review was performed on all adult nephrectomies for ADPKD by the Transplant Surgery department at Westmead Hospital between June 2011 and June 2021. Outcomes were compared between HALN, laparoscopic nephrectomy (LN) and open nephrectomy (ON) including operation time, hospital length of stay (LOS), post-operative complications, subsequent transplantation and post-transplantation wound complications.

RESULTS

Twenty-two HALN, 8 LN and 5 ON were performed during the study period. Median kidney weights for HALN, LN and ON were significantly different (1575, 403, 3420 g respectively, P = 0.001). There was a significant difference in LOS between the HALN and ON (5.8 versus 9.8 days, P = 0.04), but not between HALN and LN (5.8 versus 5.1, P = 0.06). There was no significant difference for operation time (P = 0.34) and major complication rates (P = 0.58). There were 8 HALN, 5 LN and 2 ON who have had subsequent renal transplantation with one wound complication, an incisional hernia in the HALN group.

CONCLUSION

Our HALN is associated with a shorter LOS and similar complication rate to ON and can be efficiently performed for significantly larger kidneys than LN without a significant difference in operation time or LOS. The same Rutherford-Morrison incision site can be used for transplantation.

Accuracy, Reproducibility and User Experience With Standardized Instructions for Measurement of Total Kidney Volume in Autosomal Dominant Polycystic Kidney Disease

PURPOSE

Total kidney volume (TKV) measurement is integral in clinical management of autosomal dominant polycystic kidney disease (ADPKD) but the gold standard of measurement via stereology/manual planimetry is time-consuming and not readily available to clinicians. This study assessed whether standardized measurement instructions based on an ellipsoid equation enhanced TKV assessment on computed tomographic (CT) images of the kidneys as determined by accuracy, reproducibility, efficiency and/or user acceptability.

METHODS

Participating radiologists were randomized to perform TKV measurements with or without standardized instructions. All participants measured the same 3 non-contrast, low-dose CT scans. Accuracy was assessed as variation from TKV measurements obtained by planimetry. Intraclass correlation coefficients and time to complete the measurements were assessed. Surveys assessed prior experience with TKV measurement and user acceptability of the instructions.

RESULTS

49 radiologists participated. There was no difference in accuracy or measurement time between instructed and non-instructed participants. There was a trend towards greater reproducibility with standardized instructions (ICC .8 vs .6). 92% of respondents indicated the instructions were easy to use, 86% agreed the instructions would enhance their comfort with TKV measurement and 75% agreed they would recommend these instructions to colleagues.

CONCLUSIONS

Instructed and non-instructed participants demonstrated similar accuracy and time required for TKV measurement, but instructed participants had a trend towards greater reproducibility. There was high acceptability including enhanced user confidence with the instructions. Standardized instructions may be of value for radiologists seeking to improve their confidence in providing clinicians with TKV measurements necessary to appropriately manage this patient population.

A Systematic Review of Reported Outcomes in ADPKD Studies

Introduction

Methods

Results

Conclusion

Drugs in Clinical Development to Treat Autosomal Dominant Polycystic Kidney Disease

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by progressive cyst formation that ultimately leads to kidney failure in most patients. Approximately 10% of patients who receive kidney replacement therapy suffer from ADPKD. To date, a vasopressin V2 receptor antagonist (V2RA) is the only drug that has been proven to attenuate disease progression. However, aquaresis-related adverse events limit its widespread use. Data on the renoprotective effects of somatostatin analogues differ largely between studies and medications. This review discusses new drugs that are investigated in clinical trials to treat ADPKD, such as cystic fibrosis transmembrane conductance regulator (CFTR) modulators and micro RNA inhibitors, and drugs already marketed for other indications that are being investigated for off-label use in ADPKD, such as metformin. In addition, potential methods to improve the tolerability of V2RAs are discussed, as well as methods to select patients with (likely) rapid disease progression and issues regarding the translation of preclinical data into clinical practice. Since ADPKD is a complex disease with a high degree of interindividual heterogeneity, and the mechanisms involved in cyst growth also have important functions in various physiological processes, it may prove difficult to develop drugs that target cyst growth without causing major adverse events. This is especially important since long-standing treatment is necessary in this chronic disease. This review therefore also discusses approaches to targeted therapy to minimize systemic side effects. Hopefully, these developments will advance the treatment of ADPKD.

A Case Report of Tolvaptan Therapy for ADPKD Patients With COVID-19. The Need for Appropriate Counselling for Temporary Drug Discontinuation

BACKGROUND

Patients with autosomal dominant polycystic kidney disease (ADPKD) may require specific therapy with vasopressin receptor antagonists to slow the progression of renal disease. Because of its mechanism of action, the most common side effects are polyuria, nocturia, and polydipsia. Elevations of liver enzyme levels can also occur during treatment with Tolvaptan. Temporary drug withdrawal may be indicated if the patient is unable to hydrate adequately or if there are concomitant causes of dehydration, including major infectious events. During the Coronavirus Disease 2019 (COVID-19) pandemic, this should be considered in the management of patients on Tolvaptan therapy.

CASE REPORT

We present the clinical case of a 51-year-old male with severe acute respiratory syndrome Coronavirus-2 (SARS-CoV-2) infection and ADPKD receiving Tolvaptan therapy with particular reference to the medical management of the patient during the infectious event. The patient was instructed to discontinue promptly Tolvaptan as soon as symptoms appeared. He was treated with forced hydration and symptomatic therapy. Nevertheless, a transient elevation of liver enzyme levels was detected. The timely discontinuation of Tolvaptan therapy avoided the risk of potential hepatotoxicity in a condition of known susceptibility.

CONCLUSION

Tolvaptan therapy of patients with ADPKD is safe even during SARS-CoV-2 infection. There is need for appropriate and prompt patient counseling to avoid potentially adverse side effects.

The Effect of Dietary Intervention on Autosomal-Dominant Polycystic Kidney Disease (ADPKD) Patients on Tolvaptan and Their Quality of Life

Background and objective

Autosomal-dominant polycystic kidney disease (ADPKD) is the most common inherited renal disorder; it affects people of all ethnic groups and is found in up to 10% of patients with end-stage renal disease (ESRD). Dietary intervention is important in people with renal disease, and it has been linked to greater estimated glomerular filtration rate (eGFR) preservation. Tolvaptan, an orally-active nonpeptide, selective arginine vasopressin (AVP) V2R antagonist, was recently licensed in numerous countries for the treatment of ADPKD. The aim of this study was to assess the role of dietary intervention in decreasing the osmotic load on the urine volume and its impact on the quality of life (QOL) of patients with ADPKD on tolvaptan.

Methods

This prospective cohort study was carried out at a Hamilton nephrology genetics clinic. ADPKD patients on well-tolerated doses of tolvaptan for three months were included in the study. Gitelman and Bartter Symptom Health-related QOL questionnaire was used among the study participants.

Results

Our study consisted of nine adult patients with ADPKD who were on a stable dose of tolvaptan therapy. Patients had laboratory values for urine volume, sodium (Na), and urea. No significant difference was found between pre- and post-diet intervention values in 24-hour urine volume (5.9 vs. 5.49 L/d; p=0.423), urine Na (p=0.174), and 24-hour urine urea (p=0.404).

Conclusion

Dietary intervention in ADPKD patients on tolvaptan therapy can play a vital role in improving their QOL. Further research including interventional studies and clinical trials with larger sample sizes is needed to gain deeper insight into the subject.

Potential Therapeutic Effects of Long-Term Stem Cell Administration: Impact on the Gene Profile and Kidney Function of PKD/Mhm (Cy/+) Rats

Cystic kidney disease (CKD) is a heterogeneous group of genetic disorders and one of the most common causes of end-stage renal disease. Here, we investigate the potential effects of long-term human stem cell treatment on kidney function and the gene expression profile of PKD/Mhm (Cy/+) rats. Human adipose-derived stromal cells (ASC) and human skin-derived ABCB5⁺ stromal cells (2 × 10⁶) were infused intravenously or intraperitoneally monthly, over 6 months. Additionally, ASC and ABCB5⁺-derived conditioned media were administrated intraperitoneally. The gene expression profile results showed a significant reprogramming of metabolism-related pathways along with downregulation of the cAMP, NF-kB and apoptosis pathways. During the experimental period, we measured the principal renal parameters as well as renal function using an innovative non-invasive transcutaneous device. All together, these analyses show a moderate amelioration of renal function in the ABCB5⁺ and ASC-treated groups. Additionally, ABCB5⁺ and ASC-derived conditioned media treatments lead to milder but still promising improvements. Even though further analyses have to be performed, the preliminary results obtained in this study can lay the foundations for a novel therapeutic approach with the application of cell-based therapy in CKD.

Autosomal Dominant Polycystic Kidney Disease: From Pathophysiology of Cystogenesis to Advances in the Treatment

Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic renal disease, with an estimated prevalence between 1:1000 and 1:2500. It is mostly caused by mutations of the PKD1 and PKD2 genes encoding polycystin 1 (PC1) and polycystin 2 (PC2) that regulate cellular processes such as fluid transport, differentiation, proliferation, apoptosis and cell adhesion. Reduction of calcium ions and induction of cyclic adenosine monophosphate (sAMP) promote cyst enlargement by transepithelial fluid secretion and cell proliferation. Abnormal activation of MAPK/ERK pathway, dysregulated signaling of heterotrimeric G proteins, mTOR, phosphoinositide 3-kinase, AMPK, JAK/STAT activator of transcription and nuclear factor kB (NF-kB) are involved in cystogenesis. Another feature of cystic tissue is increased extracellular production and recruitment of inflammatory cells and abnormal connections among cells. Moreover, metabolic alterations in cystic cells including defective glucose metabolism, impaired beta-oxidation and abnormal mitochondrial activity were shown to be associated with cyst expansion. Although tolvaptan has been recently approved as a drug that slows ADPKD progression, some patients do not tolerate tolvaptan because of frequent aquaretic. The advances in the knowledge of multiple molecular pathways involved in cystogenesis led to the development of animal and cellular studies, followed by the development of several ongoing randomized controlled trials with promising drugs. Our review is aimed at pathophysiological mechanisms in cystogenesis in connection with the most promising drugs in animal and clinical studies.

Dietary Interventions in Autosomal Dominant Polycystic Kidney Disease

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the progressive growth of renal cysts, leading to the loss of functional nephrons. Recommendations for individuals with ADPKD to maintain a healthy diet and lifestyle are largely similar to those for the general population. However, recent evidence from preclinical models suggests that more tightly specified dietary regimens, including caloric restriction, intermittent fasting, and ketogenic diets, hold promise to slow disease progression, and the results of ongoing human clinical trials are eagerly awaited. These dietary interventions directly influence nutrient signaling and substrate availability in the cystic kidney, while also conferring systemic metabolic benefits. The present review focuses on the importance of local and systemic metabolism in ADPKD and summarizes current evidence for dietary interventions to slow disease progression and improve quality of life.

Association of autosomal dominant polycystic kidney disease with cardiovascular disease: a US-National Inpatient Perspective

PURPOSE

Data on the epidemiology of cardiovascular diseases (CVD) in patients with autosomal dominant polycystic kidney disease (ADPKD) are limited. In this study, we assess the prevalence of CVD in patients with ADPKD and evaluate associations between these two entities.

METHODS

Using the National Inpatient Sample database, we identified 71,531 hospitalizations among adults aged ≥ 18 years with ADPKD, from 2006 to 2014 and collected relevant clinical data.

RESULTS

The prevalence of CVD in the study population was 42.6%. The most common CVD were ischemic heart diseases (19.3%), arrhythmias (14.2%), and heart failure (13.1%). The prevalence of CVD increased with the severity of renal dysfunction (RD). We found an increase in hospitalizations of patients with ADPKD and CVD over the years (p_trend < 0.01), irrespective of the degree of RD. CVD was the greatest independent predictor of mortality in these patients (OR: 3.23; 95% CI 2.38-4.38 [p < 0.001]). In a propensity matched model of hospitalizations of patients with CKD with and without ADPKD, there was a significant increase in the prevalence of atrial fibrillation/flutter (AF), pulmonary hypertension (PHN), non-ischemic cardiomyopathy (NICM), and hemorrhagic stroke among patients with ADPKD when compared to patients with similar degree of RD without ADPKD.

CONCLUSIONS

The prevalence of CVD is high among patients with ADPKD, and the most important risk factor associated with CVD is severity of RD. We found an increase in the trend of hospitalizations of patients with ADPKD associated with increased risk of AF, PHN, NICM, and hemorrhagic stroke. History of CVD is the strongest predictor of mortality among patients with ADPKD.

Incidence, risk factors and outcomes of kidney and liver cyst infection in kidney transplant recipient with autosomal dominant polycystic kidney disease

Introduction

Methods

Results

Conclusion

An update on the use of tolvaptan for ADPKD: Consensus statement on behalf of the ERA Working Group on Inherited Kidney Disorders (WGIKD), the European Rare Kidney Disease Reference Network (ERKNet) and Polycystic Kidney Disease International (PKD-International)

Approval of the vasopressin V2 receptor antagonist tolvaptan—based on the landmark TEMPO 3:4 trial—marked a transformation in the management of autosomal dominant polycystic kidney disease (ADPKD). This development has advanced patient care in ADPKD from general measures to prevent progression of chronic kidney disease to targeting disease-specific mechanisms. However, considering the long-term nature of this treatment, as well as potential side effects, evidence-based approaches to initiate treatment only in patients with rapidly progressing disease are crucial. In 2016, the position statement issued by the European Renal Association (ERA) was the first society-based recommendation on the use of tolvaptan and has served as a widely used decision-making tool for nephrologists. Since then, considerable practical experience regarding the use of tolvaptan in ADPKD has accumulated. More importantly, additional data from REPRISE, a second randomized clinical trial (RCT) examining the use of tolvaptan in later-stage disease, have added important evidence to the field, as have post hoc studies of these RCTs. To incorporate this new knowledge, we provide an updated algorithm to guide patient selection for treatment with tolvaptan and add practical advice for its use.

Metformin induces lactate accumulation and accelerates renal cyst progression in Pkd1-deficient mice

Metabolic reprogramming is a potential treatment strategy for autosomal dominant polycystic kidney disease (ADPKD). Metformin has been shown to inhibit the early stages of cyst formation in animal models. However, metformin can lead to lactic acidosis in diabetic patients with advanced chronic kidney disease, and its efficacy in ADPKD is still not fully understood. Here, we investigated the effect of metformin in an established hypomorphic mouse model of PKD that presents stable and heritable knockdown of Pkd1. The Pkd1 miRNA transgenic mice of both genders were randomized to receive metformin or saline injections. Metformin was administrated through daily intraperitoneal injection from postnatal day 35 for 4 weeks. Unexpectedly, metformin treatment at a concentration of 150 mg/kg increased disease severity, including kidney-to-body weight ratio, cystic index and plasma BUN levels, and was associated with increased renal tubular cell proliferation and plasma lactate levels. Functional enrichment analysis for cDNA microarrays from kidney samples revealed significant enrichment of several pro-proliferative pathways including β-catenin, hypoxia-inducible factor-1α, protein kinase Cα and Notch signaling pathways in the metformin-treated mutant mice. The plasma metformin concentrations were still within the recommended therapeutic range for type 2 diabetic patients. Short-term metformin treatment in a second Pkd1 hypomorphic model (Pkd1RC/RC) was however neutral. These results demonstrate that metformin may exacerbate late-stage cyst growth associated with the activation of lactate-related signaling pathways in Pkd1 deficiency. Our findings indicate that using metformin in the later stage of ADPKD might accelerate disease progression and call for the cautious use of metformin in these patients.

[What is evidence-based in the treatment of autosomal dominant polycystic kidney disease?]

The cystic transformation of the kidneys and liver are the most common symptoms of autosomal dominant polycystic kidney disease (prevalence 1:400-1:1000). A set of other manifestations can be observed less frequently, such as intracranial aneurysms. End-stage renal disease affects 50% of patients by the age of 70 years. To date, a targeted treatment is only available for patients at risk of rapidly progressive kidney failure. In 2015, the vasopressin receptor antagonist tolvaptan was approved in Germany for slowing down the decline of renal function in autosomal dominant polycystic kidney disease. Selecting the patients that benefit from tolvaptan treatment remains a major challenge. In recent years numerous clinical trials were carried out showing unspecific approaches to slow down the decline in renal function: strictly controlling blood pressure is one of the most important factors. Furthermore, unspecific approaches comprise suppression of vasopressin by sufficient fluid intake and restricted intake of salt. Weight reduction is recommended for obese patients. Lacking more causal approaches, these unspecific measures should be exploited in all patients. Currently, preclinical and clinical trials are testing numerous agents for the establishment of targeted treatment against the cystic degeneration of the kidneys and liver. This also includes dietary approaches. So far, in contrast to other genetic diseases, there are currently no gene therapy approaches for autosomal dominant polycystic kidney disease.

Pre-clinical evaluation of dual targeting of the GPCRs CaSR and V2R as therapeutic strategy for autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD), caused by mutations of PKD1 or PKD2 genes, is characterized by development and growth of cysts causing progressive kidney enlargement. Reduced resting cytosolic calcium and increased cAMP levels associated with the tonic action of vasopressin are two central biochemical defects in ADPKD. Here we show that co‐targeting two GPCRs, the vasopressin V2 receptor (V2R) and the calcium sensing receptor, using the novel V2R antagonist lixivaptan in combination with the calcimimetic R‐568, reduced cyst progression in two animal models of human PKD. Lixivaptan is expected to have a safer liver profile compared to tolvaptan, the only drug approved to delay PKD progression, based on computational model results and initial clinical evidence. PCK rat and Pkd1^RC/RC mouse littermates were fed without or with lixivaptan (0.5%) and R‐568 (0.025% for rats and 0.04% for mice), alone or in combination, for 7 (rats) or 13 (mice) weeks. In PCK rats, the combined treatment strongly decreased kidney weight, cyst and fibrosis volumes by 20%, 49%, and 73%, respectively, compared to untreated animals. In Pkd1^RC/RC mice, the same parameters were reduced by 20%, 56%, and 69%, respectively. In both cases the combined treatment appeared nominally more effective than the individual drugs used alone. These data point to an intriguing new application for two existing drugs in PKD treatment. The potential for synergy between these two compounds suggested in these animal studies, if confirmed in appropriate clinical investigations, would represent a welcome advancement in the treatment of ADPKD.

Autosomal Dominant Polycystic Kidney Disease

Autosomal Dominant Polycystic Kidney Disease is an inherited multisystemic disorder of the renal tubules with subsequent formation of multiple cysts and enlargement of the kidney, affecting various organs. Diagnosis is initially suspected in those with family history and/or individuals who develop hypertension early on (secondary hypertension) or certain symptoms. Renal function is initially preserved for years secondary to compensatory mechanisms. Associated conditions include: liver cysts, berry aneurysms, kidney stones, etc. The disease course is variable, but patients often progress to end-stage renal failure by age 60. There is no known cure, however, risk factor modification at early stages is critical. Renal transplant is the optimal treatment in ESRD.

Clinical and genetic characteristics of Korean autosomal dominant polycystic kidney disease patients

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disease. It is characterized by cyst growth in the kidneys, resulting in kidney enlargement and end-stage kidney disease. The polycystic kidney disease 1 (PKD1) and PKD2 have been identified as genes related to ADPKD and their significance in the molecular pathology of the disease has been studied. A disease-modifying drug has been approved; therefore, it has become important to identify patients at a high risk of kidney disease progression. Genetic tests, image analysis methods, and clinical factors for kidney disease progression prediction have been established. This review describes genetic and clinical characteristics, and discusses ongoing studies in Korean ADPKD patients.

Cardiovascular risk factors and the impact on prognosis in patients with chronic kidney disease secondary to autosomal dominant polycystic kidney disease

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is the most frequent hereditary renal disease. There is an increased rate of cardiovascular disease (CVD) in ADPKD. In this study, we evaluate the prevalence of cardiovascular risk factors, the achievement rates for treatment goals and cardiovascular events (CVE) in ADPKD and their relations with asymptomatic CVD in CKD from other etiologies (CKDoe) and controls.

METHODS

We evaluated 2445 CKD patients (2010-2012). The information collected was: clinical, anthropometric and analytical parameters, treatments and CVD evaluation (intima-media thickness (IMT), atheromatous plaque presence and ankle-brachial index (ABI)). Laboratory, vital status, CVE and hospitalizations were collected for 4 years.

RESULTS

ADPKD patients had a worse renal function and worst achievement of blood pressure, higher parathormone levels but lower proteinuria compared to CKDoe. ADPKD patients presented lower IMT values than other groups, however, an intermediate rate of pathologic ABI and atheromatous plaque was present. More than half of the patients received statins, achieving LDL-c levels < 100 only in 50 and 39.8% of them (ADPKD and CKDoe respectively). The number of CVE during the follow-up period was low. In adjusted Cox regression model, ADPDK had the lowest occurrence of CVE of all three groups (HR:0.422, 95%CI 0.221-0.808, p = 0.009).

CONCLUSION

ADPKD patients show intermediate control rates of CVD. A better control of CVD risk seems to be related with a lower load of CVD compared to other groups, which may lead in the long term to a better prognosis. Further investigation is necessary to determine cardiovascular prognosis in ADPKD.