Management of ESRD in patients with autosomal dominant polycystic kidney disease

Ciliopathy organoid models: a comprehensive review

Cilia are membrane-bound organelles found on the surface of most mammalian cell types and play numerous roles in human physiology and development, including osmo- and mechanosensation, as well as signal transduction. Ciliopathies are a large group of, usually rare, genetic disorders resulting from abnormal ciliary structure or ciliary dysfunction that have a high collective prevalence. Autosomal dominant or recessive polycystic kidney disease (ADPKD/ARPKD), Bardet-Biedl-Syndrome, and primary ciliary dyskinesia (PCD) are the most frequent etiologies. Rodent and zebrafish models have improved the understanding of ciliopathy pathophysiology. Yet, the limitations of these genetically modified animal strains include the inability to fully replicate the phenotypic heterogeneity found in humans, including variable multiorgan involvement. Organoids, self-assembled three-dimensional cell-based models derived from human induced pluripotent stem cells (iPSCs) or primary tissues, can recapitulate certain aspects of the development, architecture, and function of the target organ "in the dish." The potential of organoids to model patient-specific genotype-phenotype correlations has increased their popularity in ciliopathy research and led to the first preclinical organoid-based ciliopathy drug screens. This review comprehensively summarizes and evaluates current ciliopathy organoid models, focusing on kidney, airway, liver, and retinal organoids, as well as the specific methodologies used for their cultivation and for interrogating ciliary dysfunction.

Long-Term Outcomes of Nephrectomy Before Kidney Transplantation in Patients With Polycystic Kidney Disease

BACKGROUND

Polycystic kidney disease (PKD) is the most common hereditary kidney disorder. In most patients, the disease progresses to end stage kidney disease, which is treated preferably by kidney transplantation. In certain clinical circumstances, a pretransplant nephrectomy is indicated. Data regarding long-term outcomes of pretransplant nephrectomy are limited. In this study, we aimed to compare patient and graft survival, as well as other long-term outcomes of kidney transplantation, between patients with PKD who had a pretransplant nephrectomy and those who have not.

METHODS

A retrospective analysis of 112 adult kidney transplant recipients with PKD, 36 (32.14%) of which underwent a pretransplant nephrectomy.

RESULTS

In a mean follow-up period of 79 and 129 months (for patients who underwent nephrectomy and patients who did not, respectively), no significant differences were found in patient and graft survival, after adjustment to age and donor type. In addition, rate of hospitalizations, urinary tract infections requiring hospitalization, diabetes mellitus, and erythrocytosis post-transplant were similar in both cohorts.

CONCLUSIONS

Pretransplant nephrectomy in patients with PKD is not associated with increased risk of mortality and other long-term complications following kidney transplantation.

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.

Genetic Susceptibility to Chronic Kidney Disease: Links, Risks and Management

Chronic kidney disease (CKD) is associated with significant morbidity and mortality worldwide. In recent years, our understanding of genetic causes of CKD has expanded significantly with several renal conditions having been identified. This review discusses the current landscape of genetic kidney disease and their potential treatment options. This review will focus on cystic kidney disease, glomerular disease with genetic associations, congenital anomalies of kidneys and urinary tract (CAKUT), autosomal dominant-tubulointerstitial kidney disease (ADTKD), inherited nephrolithiasis and nephrocalcinosis.

Health Disparities in Kidney Failure Among Patients With Autosomal Dominant Polycystic Kidney Disease: A Cross-Sectional Study

Rationale & Objective

Understanding potential differences in patterns of kidney failure among patients with autosomal dominant polycystic kidney disease (ADPKD) may provide insights into improving disease management. We sought to characterize patients with ADPKD and kidney failure across different race/ethnicities.

Study Design

Cross-sectional study.

Setting & Participants

Kaiser Permanente Southern California members diagnosed with ADPKD between January1, 2002, and December 31, 2018.

Exposure

ADPKD.

Outcome

Kidney failure, dialysis, or receipt of kidney transplant.

Analytical Approach

Differences in characteristics by race/ethnicity were assessed using analysis of variance F test and χ² test. To compare the range and distribution of the average age at onset of kidney failure by race/ethnicity and sex, we used box plots and confidence intervals. Multivariable logistic regression was used to estimate OR for kidney transplant.

Results

Among 3,677 ADPKD patients, 1,027 (27.3%) had kidney failure. The kidney failure cohort was comprised of Black (n=138; 30.7%), White (n=496; 30.6%), Hispanic (n=306; 24.7%), and Asian (n=87; 23.6%) patients. Hispanic patients had the youngest mean age of kidney failure onset (50 years) compared to Black (56 years) and White (57 years) patients. Black (44.2%; OR, 0.72) and Hispanic (49.7%; OR, 0.65) patients had lower rates of kidney transplantation compared to White (53.8%) patients. Preemptive kidney transplantations occurred in 15.0% of patients.

Limitations

Retrospective study design and possible misclassification of ADPKD cases. Kidney function calculations were based on equations incorporating race, potentially overestimating kidney function in African Americans. The study was conducted within a single, integrated health care system in 1 geographic region and may not be generalizable to all ADPKD patients.

Conclusions

Among a large diverse ADPKD population, we observed racial/ethnic differences in rates of kidney failure, age of kidney failure onset, and rates of kidney transplantation. Our real-world ADPKD cohort provides insight into racial/ethnic variation in clinical features of disease and potential disparities in care, which may affect ADPKD outcomes.

Molecular Mechanisms of Epigenetic Regulation, Inflammation, and Cell Death in ADPKD

Autosomal dominant polycystic kidney disease (ADPKD) is a genetic disorder, which is caused by mutations in the PKD1 and PKD2 genes, characterizing by progressive growth of multiple cysts in the kidneys, eventually leading to end-stage kidney disease (ESKD) and requiring renal replacement therapy. In addition, studies indicate that disease progression is as a result of a combination of factors. Understanding the molecular mechanisms, therefore, should facilitate the development of precise therapeutic strategies for ADPKD treatment. The roles of epigenetic modulation, interstitial inflammation, and regulated cell death have recently become the focuses in ADPKD. Different epigenetic regulators, and the presence of inflammatory markers detectable even before cyst growth, have been linked to cyst progression. Moreover, the infiltration of inflammatory cells, such as macrophages and T cells, have been associated with cyst growth and deteriorating renal function in humans and PKD animal models. There is evidence supporting a direct role of the PKD gene mutations to the regulation of epigenetic mechanisms and inflammatory response in ADPKD. In addition, the role of regulated cell death, including apoptosis, autophagy and ferroptosis, have been investigated in ADPKD. However, there is no consensus whether cell death promotes or delays cyst growth in ADPKD. It is therefore necessary to develop an interactive picture between PKD gene mutations, the epigenome, inflammation, and cell death to understand why inherited PKD gene mutations in patients may result in the dysregulation of these processes that increase the progression of renal cyst formation.

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

Different Effects of Iron Indices on Mortality in Patients With Autosomal Dominant Polycystic Kidney Disease After Long-Term Hemodialysis: A Nationwide Population-Based Study

OBJECTIVE

Iron supplementation and erythropoietin stimulating agents (ESAs) are essential for maintaining hemoglobin levels in hemodialysis patients. However, patients with autosomal-dominant polycystic kidney disease (PKD) have higher endogenous erythropoietin levels, so their recommended iron indices for hemodialysis patients may differ. This study evaluated iron profiles, including ferritin levels and transferrin saturation (TSAT) to identify factors affecting mortality in patients on dialysis, and those associated with mortality in patients with and without PKD.

DESIGN

This cohort study from the Taiwan Renal Registry Data System stratified mortality risk by the presence of PKD recorded as the underlying disease.

SUBJECTS

We enrolled 1346 hemodialysis patients with PKD and 82,873 hemodialysis patients without PKD.

MAIN OUTCOME MEASURE

The primary outcome was 3-year all-cause mortality. Predictors included time-averaged and baseline serum ferritin levels and TSAT. Multivariate Cox regression analysis adjusting for age, comorbidities, and relevant laboratory parameters was used to estimate the all-cause hazard ratios (HRs) for mortality.

RESULTS

The mean ages of patients with and without PKD were 56.2±13.2 and 61.7±13.5 years and the median follow-up time was 37 (15-76) months. The adjusted mortality risks for time-averaged ferritin levels >800 ng/mL (HR=1.52; 95% confidence interval: 1.40-1.65) or TSAT levels >50% (HR=1.46; 95% confidence interval: 1.30-1.65) were significantly higher among patients without PKD than those for patients with normal iron indices. However, a U-shaped curve of mortality against ferritin/TSAT levels was not observed in patients with PKD. In the sensitivity test, there was no difference among PKD patients who underwent regular ESA therapy and those who did not.

CONCLUSION

Iron indices have different effects on mortality among patients with and without PKD. Iron supplementation, recommended serum ferritin levels, or TSAT should be monitored in hemodialysis patients, especially those without PKD. Clinicians should consider treating anemia in hemodialysis patients individually, especially in PKD.

Should kidney volume be used as an indicator of surgical occasion for patients with autosomal dominant polycystic kidney disease?

To investigate the best surgical occasion of laparoscopic cyst decortications (LCDs) in patients with autosomal dominant polycystic kidney disease (ADPKD), in accordance with the renal volume (RV). We retrospectively analyzed 135 (65 male and 70 female) patients with ADPKD who underwent LCD between June 2011 and October 2015. Patients were divided into 4 groups according to the volume of the operated kidney measured from computed tomography scans: group A (28 patients, RV < 500 mL), group B (63 patients, RV = 500-1000 mL), group C (30 patients, RV = 1000-1500 mL), and group D (14 patients, RV > 1500 mL). We studied postoperative indicators at least 1-year follow-up. For each RV group, therapeutic responses of LCD in these patients with ADPKD were assessed by improvement of clinical parameters and manifestations. A significant glomerular filtration rate (GFR) improvement was found in RV group B (31.8 ± 11.1 mL/min; final GFR 36.9 ± 12.7 mL/min; P < 0.01), and RV group C (21.1 ± 8.7 mL/min; final GFR 27.4 ± 9.2 mL/min; P < 0.01). RV group C had much higher GFR improvements than did RV group B (P < 0.01). In addition, refractory pain in patients of RV groups B, C, and D was much relieved by LCD treatment. Compared with other RV groups, blood pressures in patients with ADPKD of RV group D were also improved (P < 0.01). Our study indicates that RV could be used to evaluate LCD clinical outcomes in patients with ADPKD. The results of LCD for patients with ADPKD with RV between 500 and 1500 mL were encouraging, especially with regards to renal function improvement and pain relief. Therefore, RV may become a useful marker to predict the timing of LCD surgery in patients with ADPKD.

Healthcare resource consumption and cost of care among patients with polycystic kidney disease in Italy

Objective

The aim of this study was to assess healthcare resource consumption and its associated costs among patients with polycystic kidney disease (PKD) in a real-world setting.

Methods

An observational retrospective cohort analysis was conducted using data from the administrative databases of four Italian local health units. Data for patients who were diagnosed with PKD during the inclusion period (January 1, 2010 to December 31, 2012) were extracted. The date on which a patient’s first PKD hospitalization occurred during the inclusion period was defined as the index date (ID), and the ID was defined as the date of the first dialysis treatment recorded during the inclusion period for patients undergoing dialysis. Data regarding the clinical characteristics of patients included in the study during the 12 months prior to the ID (pre-ID; characterization period) were collected. All patients were then followed up for the 12 months following the ID (post-ID; follow-up period). Healthcare consumption and its associated costs were analyzed during the follow-up period. All costs are reported in euros (€).

Results

A total of 1,123 patients with PKD were included in this study, 61.9% of whom were male; the mean age of the patients was 57.7±24.5 years. At diagnosis, 11.2% and 1.1% of patients were affected by the dominant and recessive forms of PKD, respectively. Approximately 8% of the included patients were undergoing dialysis at ID (baseline). The incidence of dialysis was fourfold greater among patients with autosomal-dominant PKD (ADPKD) than among the total cohort (33.3% compared with an overall 8.3%). During the follow-up period, the average annual rates of healthcare resource consumption were greater among dialyzed than non-dialyzed patients. The average healthcare expenditures were €45,059.62 and €3,913.89 (p<0.001) per year for dialyzed and non-dialyzed PDK patients, respectively. Our findings suggest that in the real-world Italian context, consumption of healthcare among patients with PKD has increased at dialysis initiation due to the cost of outpatient specialist healthcare services as well as other costs. Research on the prevention of PKD-related complications and disease progression may help to facilitate a decrease in the costs associated with this condition.

Incidence and survival of end-stage kidney disease due to polycystic kidney disease in Australia and New Zealand (1963-2014)

BACKGROUND

The aim of this study was to determine whether the incidence and survival of patients with end-stage kidney disease (ESKD) due to polycystic kidney disease (PKD) has changed in Australia and New Zealand.

METHODS

Data for all PKD patients who developed ESKD and commenced renal replacement therapy (RRT) was assessed using the Australia and New Zealand Dialysis and Transplant Registry from 1963 to 2014.

RESULTS

A total 4678 patients with ESKD due to PKD received RRT during the study period. The incidence rate of ESKD (per million population per year) due to PKD rose by 3.2-fold (1970-2010), but the percentage increase between each decade decreased (54.4, 43.8, 25.6 and 6.57%). The median age of onset of new patients developing ESKD has been stable since 1990. Haemodialysis was the most common initial mode of RRT (between 62 and 76% of patients) whereas 24-29% received peritoneal dialysis. The 5-year survival rate of PKD patients on RRT (censored for transplantation and adjusted for age) improved from 26 to 84%, with the percentage increase between each successive time period being 123, 7, 21, 19 and 7.4%. The percentage of deaths on RRT due to cerebrovascular disease declined from 15 to 6%.

CONCLUSIONS

The incidence and age of onset of ESKD due to PKD has remained unchanged in the modern era though patient survival on RRT has continued to improve. These data suggest that the development and implementation of disease-specific treatments prior to RRT is needed to effectively diminish the incidence of ESKD due to PKD.

End-Stage Kidney Failure in Oman: An Analysis of Registry Data with an Emphasis on Congenital and Inherited Renal Diseases

Globally, end-stage kidney disease (ESKD) is a huge burden on health care systems. The aims of this study were to perform a comprehensive epidemiological and etiological report of ESKD patients commencing RRT in Oman with an emphasis on genetic causes and inherited kidney disease. All newly registered Omani patients with ESKD commencing RRT from 2001 until 2015 (n = 2,922) were analysed using the RRT register in Oman. All potentially genetic or inherited causes of ESKD were reviewed. In Oman, ESKD is more prevalent in males (57.1%) than females (42.9%) with a median age of incident ESKD of 53 years. Diabetic nephropathy was the most prevalent cause of ESKD (46%), followed by hypertensive nephropathy (19%), glomerulonephritis (15%), and inherited kidney disease (5%). For patients less than 20 years of age inherited kidney disease accounted for 32.5% of cases. Of this cohort with inherited renal disease, 40.3% had autosomal dominant polycystic kidney disease, 11.5% had congenital anomalies of the kidney and urinary tract, 9.4% had Alport syndrome, and 7.2% had autosomal recessive polycystic kidney disease. This study represents a comprehensive population-based epidemiological and etiological report of ESKD patients in Oman commencing RRT. Inherited kidney disease was the leading cause of paediatric ESKD.

[Polycystic kidney disease and kidney transplantation]

OBJECTIVES

To perform a state of the art about autosomal dominant polykystic kidney disease (ADPKD), management of its urological complications and end stage renal disease treatment modalities.

MATERIAL AND METHODS

An exhaustive systematic review of the scientific literature was performed in the Medline database (http://www.ncbi.nlm.nih.gov) and Embase (http://www.embase.com) using different associations of the following keywords (MESH): "autosomal dominant polykystic kidney disease", "complications", "native nephrectomy", "kidney transplantation". Publications obtained were selected based on methodology, language, date of publication (last 10 years) and relevance. Prospective and retrospective studies, in English or French, review articles; meta-analysis and guidelines were selected and analyzed. This search found 3779 articles. After reading titles and abstracts, 52 were included in the text, based on their relevance.

RESULTS

ADPKD is the most inherited renal disease, leading to end stage renal disease requiring dialysis or renal transplantation in about 50% of the patients. Many urological complications (gross hematuria, cysts infection, renal pain, lithiasis) of ADPKD required urological management. The pretransplant evaluation will ask the challenging question of native nephrectomy only in case of recurrent kidney complications or large kidney not allowing graft implantation. The optimum timing for native nephrectomy will depend on many factors (dialysis or preemptive transplantation, complication severity, anuria, easy access to transplantation, potential living donor).

CONCLUSION

Pretransplant management of ADPKD is challenging. A conservative strategy should be promoted to avoid anuria (and its metabolic complications) and to preserve a functioning low urinary tract and quality of life. When native nephrectomy should be performed, surgery remains the gold standard but renal arterial embolization may be a safe option due to its low morbidity.

Pre-transplant treatment of large polycystic kidney

AIM: To evaluate the indications, optimal timing and outcomes of native nephrectomy and other techniques in pretransplant treatment of autosomal dominant polycystic kidney disease (PKD).

METHODS: A literature review was conducted using the PubMed and Epistemonikos databases. Keywords for pre-transplant surgical management of polycystic kidneys were: Transplant, treatment and PKD. Keywords for pre-treatment embolization of PKD were: Embolization, transplant and polycystic kidney disease. The inclusion criterions were all articles found using this search method. The exclusion criterions were articles found to include bias and not attending pre-transplant treatment options. Fifteen articles were included in our final analysis. Ten articles were found regarding embolization of PKD of which three reviews were selected for final analysis. The reviews were divided into pre transplant and intra transplant treatment for the surgical treatment of PKD. All articles meeting inclusion criteria were thoroughly analyzed by two independent reviewers. A third independent reviewer was consulted if the reviewers did not agree upon the inclusion or exclusion of a specific article. No statistical analysis was performed.

RESULTS: Studies vary regarding the technique used (open or laparoscopic), laterality (single or bilateral) and temporality of nephrectomy with respect to renal transplant (pre-transplant or simultaneous to transplant). Several groups argue in favor of simultaneous nephrectomy and kidney transplant since it avoids the deleterious effects of being anefric. Long-term results and patient satisfaction are acceptable. However, it is associated with increased operative time, transfusion rate, morbidity and length of hospital stay. Based on small sample studies, bilateral nephrectomy prior to transplant has been associated with a higher risk of morbidity and mortality. Studies on laparoscopic approach report it as a feasible and safe alternative to the open surgery approach, highlighting its lower complication rate, transfusions and shorter hospital stay. Arterial embolization of the kidney appears as an effective and low morbid alternative for the management of large native kidneys. The reduction in renal size allow transplant in a significant number of patients, which makes it an appealing alternative to surgery.

CONCLUSION: There is limited evidence regarding best pretrasnplant treatment of large PKD but to date embolization seems an appealing alternative to augment space for renal graft allocation.

Ouabain Enhances ADPKD Cell Apoptosis via the Intrinsic Pathway

Progression of autosomal dominant polycystic kidney disease (ADPKD) is highly influenced by factors circulating in blood. We have shown that the hormone ouabain enhances several characteristics of the ADPKD cystic phenotype, including the rate of cell proliferation, fluid secretion and the capacity of the cells to form cysts. In this work, we found that physiological levels of ouabain (3 nM) also promote programmed cell death of renal epithelial cells obtained from kidney cysts of patients with ADPKD (ADPKD cells). This was determined by Alexa Fluor 488 labeled-Annexin-V staining and TUNEL assay, both biochemical markers of apoptosis. Ouabain-induced apoptosis also takes place when ADPKD cell growth is blocked; suggesting that the effect is not secondary to the stimulatory actions of ouabain on cell proliferation. Ouabain alters the expression of BCL family of proteins, reducing BCL-2 and increasing BAX expression levels, anti- and pro-apoptotic mediators respectively. In addition, ouabain caused the release of cytochrome c from mitochondria. Moreover, ouabain activates caspase-3, a key “executioner” caspase in the cell apoptotic pathway, but did not affect caspase-8. This suggests that ouabain triggers ADPKD cell apoptosis by stimulating the intrinsic, but not the extrinsic pathway of programmed cell death. The apoptotic effects of ouabain are specific for ADPKD cells and do not occur in normal human kidney cells (NHK cells). Taken together with our previous observations, these results show that ouabain causes an imbalance in cell growth/death, to favor growth of the cystic cells. This event, characteristic of ADPKD, further suggests the importance of ouabain as a circulating factor that promotes ADPKD progression.

Vascular complications in autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary kidney disease. Relentless cyst growth substantially enlarges both kidneys and culminates in renal failure. Patients with ADPKD also have vascular abnormalities; intracranial aneurysms (IAs) are found in ∼10% of asymptomatic patients during screening and in up to 25% of those with a family history of IA or subarachnoid haemorrhage. As the genes responsible for ADPKD—PKD1 and PKD2—have complex integrative roles in mechanotransduction and intracellular calcium signalling, the molecular basis of IA formation might involve focal haemodynamic conditions exacerbated by hypertension and altered flow sensing. IA rupture results in substantial mortality, morbidity and poor long-term outcomes. In this Review, we focus mainly on strategies for screening, diagnosis and treatment of IAs in patients with ADPKD. Other vascular aneurysms and anomalies—including aneurysms of the aorta and coronary arteries, cervicocephalic and thoracic aortic dissections, aortic root dilatation and cerebral dolichoectasia—are less common in this population, and the available data are insufficient to recommend screening strategies. Treatment decisions should be made with expert consultation and be based on a risk-benefit analysis that takes into account aneurysm location and morphology as well as patient age and comorbidities.

Current management of autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD), the most frequent cause of genetic renal disease affecting approximately 4 to 7 million individuals worldwide and accounting for 7%-15% of patients on renal replacement therapy, is a systemic disorder mainly involving the kidney but cysts can also occur in other organs such as the liver, pancreas, arachnoid membrane and seminal vesicles. Though computed tomography and magnetic resonance imaging (MRI) were similar in evaluating 81% of cystic lesions of the kidney, MRI may depict septa, wall thickening or enhancement leading to upgrade in cyst classification that can affect management. A screening strategy for intracranial aneurysms would provide 1.0 additional year of life without neurological disability to a 20-year-old patient with ADPKD and reduce the financial impact on society of the disease. Current treatment strategies include reducing: cyclic adenosine monophosphate levels, cell proliferation and fluid secretion. Several randomised clinical trials (RCT) including mammalian target of rapamycin inhibitors, somatostatin analogues and a vasopressin V2 receptor antagonist have been performed to study the effect of diverse drugs on growth of renal and hepatic cysts, and on deterioration of renal function. Prophylactic native nephrectomy is indicated in patients with a history of cyst infection or recurrent haemorrhage or to those in whom space must be made to implant the graft. The absence of large RCT on various aspects of the disease and its treatment leaves considerable uncertainty and ambiguity in many aspects of ADPKD patient care as it relates to end stage renal disease (ESRD). The outlook of patients with ADPKD is improving and is in fact much better than that for patients in ESRD due to other causes. This review highlights the need for well-structured RCTs as a first step towards trying newer interventions so as to develop updated clinical management guidelines.

[Pathophysiology, epidemiology, clinical presentation, diagnosis and treatment options for autosomal dominant polycystic kidney disease]

Autosomal dominant polycystic kidney disease (ADPKD) is the leading genetic cause of end-stage renal disease (ESRD) worldwide. Its prevalence is evaluated according to studies and population between 1/1000 and 1/4000 live births and it accounts for 6 to 8% of incident ESRD patients in developed countries. ADPKD is characterized by numerous cysts in both kidneys and various extrarenal manifestations that are detailed in this review. Clinico-radiological and genetic diagnosis are also discussed. Mutations in the PKD1 and PKD2 codifying for polycystin-1 (PC-1) and polycystin-2 (PC-2) are responsible for the 85 and 15% of ADPKD cases, respectively. In primary cilia of normal kidney epithelial cells, PC-1 and PC-2 interact forming a complex involved in flow- and cilia-dependant signalling pathways where intracellular calcium and cAMP play a central role. Alteration of these multiple signal transduction pathways leads to cystogenesis accompanied by dysregulated planar cell polarity, excessive cell proliferation and fluid secretion, and pathogenic interactions of epithelial cells with an abnormal extracellular matrix. The mass effect of expanding cyst is responsible for the decline in glomerular filtration rate that occurs late in the course of the disease. For many decades, the treatment for ADPKD aims to lessen the condition's symptoms, limit kidney damage, and prevent complications. Recently, the development of promising specific treatment raises the hope to slow the growth of cysts and delay the disease. Treatment strategies targeting cAMP signalling such as vasopressin receptor antagonists or somatostatin analogs have been tested successfully in clinical trials with relative safety. Newer treatments supported by preclinical trials will become available in the next future. Recognizing early markers of renal progression (clinical, imaging, and genetic markers) to identify high-risk patients and multidrug approaches with synergistic effects may provide new opportunities for the treatment of ADPKD.

Embolization of renal arteries before transplantation in patients with polycystic kidney disease: a single institution long-term experience

PURPOSE

We aimed to retrospectively assess the long-term safety and efficacy of embolization of renal arteries (ERA) in patients with polycystic kidney disease (PKD) before renal transplantation.

MATERIAL AND METHODS

Between January 2008 and November 2013, 82 ERA procedures were performed on 76 kidneys in 73 patients (mean age 53 years, range: 34-72). All patients had terminal-stage PKD and were under dialysis and on the renal transplant waiting list with a temporary contraindication due to excessive renal volume.

RESULTS

ERA was considered successful in 89.5% (68/76) of embolized kidneys, meaning that the temporary contraindication for transplantation could be withdrawn for 65 patients (on average 5.6 months, range: 2.8-24.3, after ERA). Mean volume reduction was 40 (range: 2-69) at 3 months and 59% (35-86) thereafter (both p < 0.001). Post-embolization syndrome occurred after 15 of 82 procedures (18.3%). The severe complication rate was 4.9%. Forty-three (67.7%) transplantations were successfully conducted after ERA, with a mean follow-up of 26.2 months (range: 1.8-59.5), and the estimated 5-year graft survival rate was 95.3% [95% CI: 82.7-98.8].

CONCLUSIONS

ERA is a safe and effective alternative to nephrectomy before renal transplantation in patients with PKD.

KEY POINTS

• Embolization of non-functioning polycystic kidneys allowed transplantation in 89.5% of cases. • Technical failure rate was 7.9% after embolization, irrespective of the technique used. • Post-embolization syndrome occurred after 18.3% of the procedures. • A low rate of severe complications (4.9%) was observed after renal embolization.

A painful inheritance-patient perspectives on living with polycystic kidney disease: thematic synthesis of qualitative research

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is a life-threatening genetic disorder and has multiple complications including, infection, pain, intracranial aneurysm and kidney failure leading to significantly impaired quality of life and reduced survival. These outcomes are well described, but patient perspectives and experiences of living with ADPKD are under-recognized.

METHODS

MEDLINE, Embase, PsycINFO and CINAHL were searched to August 2014. Studies were analyzed using thematic synthesis.

RESULTS

From 21 studies (n = 247), we derived five themes: unvalidated pain (medical trivialization, inadequacy of pain management); persisting uncertainties and ambiguities (lacking diagnostic clarity, disempowerment in self-care, unpredictable daily disruptions, inability to plan ahead, financial discrimination); genetic guilt and resentment (blaming parents, self-blame, constant burden of guilt); precariousness in pursuing parenthood (prognostic uncertainty, owning the decision, needing directive counselling); and defining parental responsibility for genetic testing and disclosure (preserving normality, doubting necessity of genetic testing, respecting the child's autonomy and hope in future technologies, facilitating preparedness).

CONCLUSIONS

The erratic onset of pain contributes to the substantial unpredictability of daily living and prevents patients from establishing long-term life goals. Decisions about family planning, genetic testing of children and disclosure involves making profoundly difficult judgments about ethical parental responsibility. Patient engagement in pain management, strategies for self-care, counselling to reduce the burden of 'genetic guilt' and specific family planning decision support tools may be priorities for care to improve patient-centred outcomes in ADPKD.

Spanish guidelines for the management of autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is the most frequent cause of genetic renal disease and accounts for 6-10% of patients on renal replacement therapy (RRT). Very few prospective, randomized trials or clinical studies address the diagnosis and management of this relatively frequent disorder. No clinical guidelines are available to date. This is a consensus statement presenting the recommendations of the Spanish Working Group on Inherited Kidney Diseases, which were agreed to following a literature search and discussions. Levels of evidence found were C and D according to the Centre for Evidence-Based Medicine (University of Oxford). The recommendations relate to, among other topics, the use of imaging and genetic diagnosis, management of hypertension, pain, cyst infections and bleeding, extra-renal involvement including polycystic liver disease and cranial aneurysms, management of chronic kidney disease (CKD) and RRT and management of children with ADPKD. Recommendations on specific ADPKD therapies are not provided since no drug has regulatory approval for this indication.

Maximal kidney length predicts need for native nephrectomy in ADPKD patients undergoing renal transplantation

INTRODUCTION

Native nephrectomy in patients with autosomal dominant polycystic kidney disease (ADPKD) is performed on a case-by-case basis. We determine if pre-transplant maximal kidney length (MKL) can be used to predict ultimate nephrectomy status.

METHODS

We performed a retrospective review of ADPKD patients who underwent renal transplantation at our centre between January 2000 and December 2012. Pre-transplant measurements of MKL alone, MKL adjusted for height (HtMKL), weight (WtMKL) and body mass index (BMI-MKL) were each assessed for their predictive ability via a receiver operating characteristic (ROC) curve analysis.

RESULTS

In total, 84 patients met our inclusion criteria, of which 17 (20.2%) underwent native nephrectomy. An MKL ROC curve analysis revealed an area under the curve (AUC) of 0.867 (95% confidence interval [CI] 0.775-0.931; p < 0.001). An optimal cutoff criterion of >21.5 cm revealed a sensitivity of 94.1% (95% CI 71.3-99.9) and specificity of 70.1% (95% CI 57.7-80.7) for eventual nephrectomy. The AUC of HtMKL, WtMKL and BMI-MKL ROC curves did not differ significantly from MKL alone. HtMKL improved specificity, but not overall test performance. The determination of the cut-off MKL may be influenced by the single-centre retrospective nature of this analysis, as well as the fact that renal size was determined by ultrasound and not computerized tomography or magnetic resonance imaging.

CONCLUSION

MKL in patients with ADPKD is associated with the eventual need for nephrectomy and may be a useful clinical tool to risk stratify these patients and therefore guide patient conversations to a decision to leave the native kidneys in situ.

Renal transplantation in autosomal dominant polycystic kidney disease

In patients with autosomal dominant polycystic kidney disease (ADPKD) evaluated for kidney transplantation, issues related to native nephrectomy, cystic liver involvement, screening for intracranial aneurysms and living-related kidney donation deserve special consideration. Prophylactic native nephrectomy is restricted to patients with a history of cyst infection or recurrent haemorrhage or to those in whom space must be made to implant the graft. Patients with liver involvement require pretransplant imaging. Selection of patients for pretransplant screening of intracranial aneurysms should follow the general recommendations for patients with ADPKD. In living related-donor candidates aged <30 years and at-risk of ADPKD, molecular genetic testing should be carried out when ultrasonography and MRI findings are normal or equivocal. After kidney transplantation, patient and graft survival rates are excellent and the volume of native kidneys decreases. However, liver cysts continue to grow and treatment with a somatostatin analogue should be considered in patients with massive cyst involvement. Cerebrovascular events have a marginal effect on post-transplant morbidity and mortality. An increased risk of new-onset diabetes mellitus and nonmelanoma skin cancers has been reported, but several studies have challenged these findings. Finally, no data currently support the preferential use of mammalian target of rapamycin inhibitors as immunosuppressive agents in transplant recipients with ADPKD.

Renal replacement therapy in ADPKD patients: a 25-year survey based on the Catalan registry

Background

Some 7-10% of patients on replacement renal therapy (RRT) are receiving it because of autosomal dominant polycystic kidney disease (ADPKD). The age at initiation of RRT is expected to increase over time.

Methods

Clinical data of 1,586 patients (7.9%) with ADPKD and 18,447 (92.1%) patients with other nephropathies were analysed from 1984 through 2009 (1984–1991, 1992–1999 and 2000–2009).

Results

The age at initiation of RRT remained stable over the three periods in the ADPKD group (56.7 ± 10.9 (mean ± SD) vs 57.5 ± 12.1 vs 57.8 ± 13.3 years), whereas it increased significantly in the non-ADPKD group (from 54.8 ± 16.8 to 63.9 ± 16.3 years, p < 0.001). The ratio of males to females was higher for non-ADPKD than for ADPKD patients (1.6–1.8 vs 1.1–1.2). The prevalence of diabetes was significantly lower in the ADPKD group (6.76% vs 11.89%, p < 0.001), as were most of the co-morbidities studied, with the exception of hypertension. The survival rate of the ADPKD patients on RRT was higher than that of the non-ADPKD patients (p < 0.001).

Conclusions

Over time neither changes in age nor alterations in male to female ratio have occurred among ADPKD patients who have started RRT, probably because of the impact of unmodifiable genetic factors in the absence of a specific treatment.

Novel role of ouabain as a cystogenic factor in autosomal dominant polycystic kidney disease

The classic role of the Na-K-ATPase is that of a primary active transporter that utilizes cell energy to establish and maintain transmembrane Na(+) and K(+) gradients to preserve cell osmotic stability, support cell excitability, and drive secondary active transport. Recent studies have revealed that Na-K-ATPase located within cholesterol-containing lipid rafts serves as a receptor for cardiotonic steroids, including ouabain. Traditionally, ouabain was viewed as a toxin produced only in plants, and it was used in relatively high concentrations to experimentally block the pumping action of the Na-K-ATPase. However, the new and unexpected role of the Na-K-ATPase as a signal transducer revealed a novel facet for ouabain in the regulation of a myriad of cell functions, including cell proliferation, hypertrophy, apoptosis, mobility, and metabolism. The seminal discovery that ouabain is endogenously produced in mammals and circulates in plasma has fueled the interest in this endogenous molecule as a potentially important hormone in normal physiology and disease. In this article, we review the role of the Na-K-ATPase as an ion transporter in the kidney, the experimental evidence for ouabain as a circulating hormone, the function of the Na-K-ATPase as a signal transducer that mediates ouabain's effects, and novel results for ouabain-induced Na-K-ATPase signaling in cystogenesis of autosomal dominant polycystic kidney disease.

Simultaneous kidney transplantation and bilateral native nephrectomy for polycystic kidney disease

PURPOSE

Bilateral native nephrectomy with simultaneous kidney transplantation is becoming more common for patients with polycystic kidney disease in the living donor nephrectomy era. Single center reports evaluating the short-term and long-term outcomes of simultaneous kidney transplantation have been published but are generally limited by small sample sizes. We examined population level data to broadly define the complications of simultaneous kidney transplantation.

MATERIALS AND METHODS

The Nationwide Inpatient Sample (NIS) was used to acquire data on 2,368 patients with polycystic kidney disease treated with bilateral native nephrectomy between 1998 and 2010. We performed unadjusted, multivariable and propensity score adjusted analyses of postoperative outcomes.

RESULTS

A total of 2,368 patients were included in this study. The 271 patients (11.4%) who underwent simultaneous kidney transplantation had higher rates of intraoperative hemorrhage, blood transfusion and urological complications (propensity score adjusted OR 3.3, p=0.01, OR 4.2, p<0.0001 and OR 5.5, p<0.0001, respectively) but a lower in-hospital mortality rate (15.8% vs 1.1%, propensity score adjusted OR 0.10, p<0.0001). Median hospitalization was also significantly higher in patients who underwent simultaneous kidney transplantation (6 vs 9 days, p<0.0001). For the top quartile of high volume hospitals the rates of intraoperative hemorrhage, blood transfusion and urological complications remained statistically higher in patients treated with simultaneous kidney transplantation but in-hospital mortality was similar on multivariable logistic regression (OR 0.2, p=0.17).

CONCLUSIONS

Except for increased rates of intraoperative hemorrhage, blood transfusion and urological complications there were no significant differences in postoperative adverse outcomes in this large, population based study of patients who underwent simultaneous kidney transplantation compared to bilateral native nephrectomy alone.

Autosomal dominant polycystic kidney disease with ectopic unilateral multicystic dysplastic kidney

Background

Autosomal dominant polycystic kidney disease (ADPKD) is the most common hereditary renal disorder. In most cases, ADPKD similarly affects bilateral kidneys.

Case presentation

Among the 605 ADPKD patients that were followed up by our center, we identified two male patients with unilateral ADPKD. The cases were remarkable because the patients also had ectopia and multicystic dysplasia in the contralateral kidney, which are generally sporadic disease conditions. Both patients tested positive for polycystic kidney disease 1 mutation, but negative for hepatocyte nuclear factor 1 beta mutation. Moreover, the deterioration of their kidney function seemed to be quicker than their age- and sex-matched controls and siblings. Both patients had started a long-term hemodialysis in their 40s.

Conclusion

Anatomical and genetic abnormality in patients with ADPKD may be more frequent and complex than previously believed. The compensatory capacity in patients with ADPKD is fragile, and missing one kidney could accelerate the deterioration of renal function.

Kidney transplantation with and without simultaneous bilateral native nephrectomy in patients with polycystic kidney disease: a comparative retrospective study

BACKGROUND

Patients with autosomal dominant polycystic kidney disease (ADPKD) often need to undergo native nephrectomy and are candidates for kidney transplantation. The necessity and timing of nephrectomy are controversial. Some authors recommend simultaneous bilateral native nephrectomy (SBN) as the preferred option in living-donor kidney transplantation (LDKT). These recommendations are based on small study populations. We therefore set out to study outcomes of LDKT with SBN, compared with LDKT alone in a larger single-center cohort.

METHODS

A consecutive series of 159 patients with ADPKD undergoing LDKT were included in the study. Of the 159 patients, 2 were excluded because of missing data, 79 underwent LDKT alone (group A), and 78 underwent LDKT with SBN (group B). Demographic data and intraoperative and postoperative data were collected from patient charts and the national kidney registry.

RESULTS

There were no differences regarding background data. Group B experienced significantly longer operating times (183.7 vs. 319.3 min, P<0.001), a greater need for blood transfusions (0.1 vs. 1.6 units, P<0.001) and plasma products (35.1 vs. 438.3 mL, P<0.001), and longer hospital stays (11.8 vs. 15.4 days, P<0.001). It also experienced more intraoperative events and postoperative complications but fewer reoperations/reinterventions. There were no differences in patient and graft survival rates.

CONCLUSIONS

SBN in patients undergoing LDKT for ADPKD does not have a significant negative impact on patient and graft survival rates. It obviates a separate surgical procedure but requires longer hospital stay. It may be associated with more postoperative complications and risk of graft loss. These considerations should be communicated to the recipient and the donor.

Mineral and bone disorders and survival in hemodialysis patients with and without polycystic kidney disease

BACKGROUND

Maintenance hemodialysis (MHD) patients with polycystic kidney disease (PKD) have better survival than non-PKD patients. Mineral and bone disorders (MBD) are associated with accelerated atherosclerosis and cardiovascular death in MHD patients. It is unknown whether the different MBD mortality association between MHD populations with and without PKD can explain the survival differential.

METHODS

Survival models were examined to assess the association between different laboratory markers of MBD [such as serum phosphorous, parathyroid hormone (PTH), calcium and alkaline phosphatase] and mortality in a 6-year cohort of 60,089 non-PKD and 1501 PKD MHD patients.

RESULTS

PKD and non-PKD patients were 57±13 and 62±15 years old and included 46 and 45% women and 14 and 32% Blacks, respectively. Whereas PKD individuals with PTH 150 to <300 pg/mL (reference) had the lowest risk for mortality, the death risk was higher in patients with PTH<150 [hazard ratio (HR): 2.16 (95% confidence interval 1.53-3.06)], 300 to <600 [HR: 1.30 (0.97-1.74)] and ≥600 pg/mL [HR: 1.46 (1.02-2.08)], respectively. Similar patterns were found in non-PKD patients. Fully adjusted death HRs of time-averaged serum phosphorous increments<3.5, 5.5 to <7.5 and ≥7.5 mg/dL (reference: 3.5 to <5.5 mg/dL) for PKD patients were 2.82 (1.50-5.29), 1.40 (1.12-1.75) and 2.25 (1.57-3.22). The associations of alkaline phosphatase and calcium with mortality were similar in PKD and non-PKD patients.

CONCLUSION

Bone-mineral disorder markers exhibit similar mortality trends between PKD and non-PKD MHD patients, although some differences are observed in particular in low PTH and phosphorus ranges.

Metabolomics in the study of kidney diseases

Metabolomics--the nontargeted measurement of all metabolites produced by the body--is beginning to show promise in both biomarker discovery and, in the form of pharmacometabolomics, in aiding the choice of therapy for patients with specific diseases. In its two basic forms (pattern recognition and metabolite identification), this developing field has been used to discover potential biomarkers in several renal diseases, including acute kidney injury (attributable to a variety of causes), autosomal dominant polycystic kidney disease and kidney cancer. NMR and gas chromatography or liquid chromatography, together with mass spectrometry, are generally used to separate and identify metabolites. Many hurdles need to be overcome in this field, such as achieving consistency in collection of biofluid samples, controlling for batch effects during the analysis and applying the most appropriate statistical analysis to extract the maximum amount of biological information from the data obtained. Pathway and network analyses have both been applied to metabolomic analysis, which vastly extends its clinical relevance and effects. In addition, pharmacometabolomics analyses, in which a metabolomic signature can be associated with a given therapeutic effect, are beginning to appear in the literature, which will lead to personalized therapies. Thus, metabolomics holds promise for early diagnosis, increased choice of therapy and the identification of new metabolic pathways that could potentially be targeted in kidney disease.

Metabolomics in the study of kidney diseases

Metabolomics--the nontargeted measurement of all metabolites produced by the body--is beginning to show promise in both biomarker discovery and, in the form of pharmacometabolomics, in aiding the choice of therapy for patients with specific diseases. In its two basic forms (pattern recognition and metabolite identification), this developing field has been used to discover potential biomarkers in several renal diseases, including acute kidney injury (attributable to a variety of causes), autosomal dominant polycystic kidney disease and kidney cancer. NMR and gas chromatography or liquid chromatography, together with mass spectrometry, are generally used to separate and identify metabolites. Many hurdles need to be overcome in this field, such as achieving consistency in collection of biofluid samples, controlling for batch effects during the analysis and applying the most appropriate statistical analysis to extract the maximum amount of biological information from the data obtained. Pathway and network analyses have both been applied to metabolomic analysis, which vastly extends its clinical relevance and effects. In addition, pharmacometabolomics analyses, in which a metabolomic signature can be associated with a given therapeutic effect, are beginning to appear in the literature, which will lead to personalized therapies. Thus, metabolomics holds promise for early diagnosis, increased choice of therapy and the identification of new metabolic pathways that could potentially be targeted in kidney disease.

Blood pressure and survival in long-term hemodialysis patients with and without polycystic kidney disease

BACKGROUND

In maintenance dialysis patients, low blood pressure (BP) values are associated with higher death rates when compared with normal to moderately high values. This 'hypertension paradox' may be related to comorbid conditions. Dialysis patients with polycystic kidney disease (PKD) usually have a lower comorbidity burden and greater survival. We hypothesized that in PKD dialysis patients, a representative of a healthier dialysis patient population, high BP is associated with higher mortality.

METHODS

Time-dependent survival models including after multivariate adjustment were examined to assess the association between prehemodialysis and posthemodialysis BP and all-cause mortality in a 5-year cohort of 67 085 non-PKD and 1579 PKD hemodialysis patients.

RESULTS

In PKD patients, low prehemodialysis and posthemodialysis SBPs were associated with increased mortality, whereas high prehemodialysis DBP was associated with greater survival. Fully adjusted death hazard ratios (and 95% confidence levels) for prehemodialysis and posthemodialysis BP of less than 120 mmHg (reference 140 to <160 mmHg) were 1.30 (1.06-1.92) and 1.45 (1.04-2.02), respectively, and for prehemodialysis DBP of 80 mmHg or more (reference 70 to <80 mmHg) was 0.68 (0.49-0.93, all P values <0.05). Similar associations were observed in non-PKD patients. In pooled analyses, within each commensurate BP stratum, PKD patients exhibited superior survival to non-PKD patients.

CONCLUSION

Among hemodialysis patients, those with PKD display a similar BP paradox as those without PKD, even though within each BP category PKD patients maintain superior survival. Randomized clinical trials are needed to define optimal blood pressure targets in the hemodialysis population.