Citations

We provide the first longitudinal and most comprehensive analysis of the intrarenal microvasculature in a slowly progressive model of autosomal dominant polycystic kidney disease (ADPKD) and integrate the findings with studies in a young cohort of individuals with ADPKD. We identified vasculature-related pathways that could be targeted for therapeutic interventions and contribute promising, noninvasive biomarkers in patients with ADPKD. Alterations of the intrarenal microcirculation may affect drug delivery; a better understanding of its longitudinal changes may aid in treatment management.

Key Points Experimental autosomal dominant polycystic kidney disease is associated with longitudinal changes in the kidney micro-RNA and mRNA profiles. Alterations in cellular transport, a feature of CKD, and a common biological process within polycystic kidney disease models and human autosomal dominant polycystic kidney disease, is present from early stages. Early versus late micro-RNA expression changes in autosomal dominant polycystic kidney disease could be targeted for a more tailored therapeutic intervention in the disease. Background Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the progressive development and enlargement of bilateral kidney cysts, which often leads to kidney failure. This study comprehensively characterized the expression profile of micro-RNAs (miRNAs) and their target genes in Pkd1 RC/RC mice and further compared them with other murine models of polycystic kidney disease (PKD) and a model of CKD and individuals with ADPKD. Methods Pkd1 RC/RC and wild-type (WT) mice ( n =10 each, five males and five females) were studied at 1, 6, and 12 months. At each time point, kidney volume was determined in vivo (magnetic resonance imaging), followed by ex vivo histomorphometric analyses. In randomly selected Pkd1 RC/RC and WT mouse kidneys ( n =5/genotype, at 1 and 12 months), miRNA-sequencing (seq) was performed, followed by mRNA-seq, integrated (miRNA-seq/mRNA-seq analysis), and functional analysis of miRNA target genes. Venn diagrams were constructed to identify overlapping and novel differentially expressed (DE) miRNAs in Pkd1 RC/RC and other commonly used murine models of PKD, diabetic kidney disease, and individuals with ADPKD. Results miRNA-seq analysis identified 41 and 181 miRNAs DE in Pkd1 RC/RC versus WT kidneys at 1 and 12 months, respectively, which were confirmed by quantitative PCR. Target genes of miRNAs DE in Pkd1 RC/RC at early stages encoded for proteins mainly implicated in cell proliferation and α -ketoglutarate ( α -KG) transport, whereas those DE at late stages encoded for transport proteins involved in proinflammatory and metabolic processes. Urine α -KG concentration ( 1 H nuclear magnetic resonance spectroscopy), its fractional excretion, and tissue levels were higher in Pkd1 RC/RC during the entire course of the disease and associated with decreased protein expression of α -KG transporters sodium-coupled dicarboxylate transporter 3 and organic anion transporter 1. We further identified common DE miRNAs among murine models of PKD, diabetic kidney disease, and previous reports in individuals with ADPKD, as well as several novel miRNAs DE in early and late Pkd1 RC/RC kidneys, which have not been previously reported in either other murine models of PKD or patients with ADPKD. Conclusions Our study demonstrates that the renal miRNA expression profile changes longitudinally with the progression of the disease and might suggest that the post-transcriptional regulation of α -KG transport could represent a novel early feature of the disease.

Key Points The kidney microvasculature was quantified reliably in human autosomal dominant polycystic kidney disease early on, using super-resolution ultrasound localization microscopy. Microvascular parameters correlated with structural and functional indices, constituting promising biomarkers to evaluate noncystic parenchyma. Microvascular parameters may serve to assess disease severity and monitor progression from the early stages of the disease. Background In vitro studies in individuals with autosomal dominant polycystic kidney disease (ADPKD) have shown extensive intrarenal microvascular remodeling. However, analyses have been limited to the time of kidney failure because of the invasive nature of current methodologies to assess the intrarenal microvasculature. We hypothesized that super-resolution ultrasound microvascular imaging, known as ultrasound localization microscopy, enabled by high-framerate ultrasound imaging and microbubble localization and tracking postprocessing techniques, would safely, reliably, and reproducibly assess the intrarenal microvasculature in individuals with ADPKD at an early stage of the disease. Methods We prospectively enrolled young (<40 years of age), well-characterized, early-stage (eGFR >90 ml/min per 1.73 m 2 ) individuals with ADPKD, and sex–age 1:1 matched controls ( n =17 each) and assessed the intrarenal microvasculature using ultrasound localization microscopy. We determined the intersonographer reliability, intraobserver repeatability, and interobserver reproducibility of microvascular parameters in both groups, and the day-to-day variability in the control group. Microvascular parameters were correlated with structural (total kidney volume) and functional (eGFR) markers in individuals with ADPKD. Results Ultrasound localization microscopy provided a super-resolved map of the intrarenal microvasculature in ADPKD and matched controls. Intrarenal microvascular parameters ( e.g ., vessel density) were quantified in a safe, reliable (intraclass correlation coefficients, 0.96; 95% confidence interval, 0.91 to 0.98), reproducible (intraclass correlation coefficient, 0.96; 95% confidence interval, 0.93 to 0.98), and repeatable (coefficient of variations, 3.6%) manner. In control individuals, the day-to-day variability of most parameters was low, with coefficient of variation ranging from 1.8% to 10.7%. Microvascular parameters differed in individuals with ADPKD compared with controls, despite preserved eGFR. Interestingly, cortical vessel density and its derived perfusion correlated directly with eGFR, whereas tortuosity indices presented an inverse correlation. Conclusions Ultrasound localization microscopy provided a safe and reliable in vivo assessment of the human intrarenal microvasculature.

Key Points Automated cyst segmentation in autosomal dominant polycystic kidney disease could transform care by enabling precise monitoring of cyst progression with minimal manual effort. This technology can facilitate more consistent assessments of cyst burden across patients. Translating these segmentation models from magnetic resonance imaging to computed tomography is crucial for providing comprehensive, modality-independent evaluations. Background Total kidney and liver volumes are key image-based biomarkers to predict the severity of kidney and liver phenotype in autosomal dominant polycystic kidney disease (ADPKD). However, magnetic resonance (MR) imaging-based advanced biomarkers like total cyst number and cyst parenchyma surface area have been shown to more accurately assess cyst burden and improve the prediction of disease progression. The main aim of this study was to extend the calculation of advanced biomarkers to other imaging modalities; thus, we propose a fully automated model to segment kidney and liver cysts in computed tomography (CT) images. Methods Abdominal CTs of patients with ADPKD were gathered retrospectively between 2001 and 2018. A three-dimensional deep learning method using the nnU-Net architecture was trained to learn cyst edges-cores and the noncystic kidney/liver parenchyma. Separate segmentation models were trained for kidney cysts in contrast-enhanced CTs and liver cysts in noncontrast CTs using an active learning approach. Two experienced research fellows manually generated the reference standard segmentation, which were reviewed by an expert radiologist for accuracy. Results Two-hundred CT scans from 148 patients (mean age, 51.2±14.1 years; 48% male) were used for model training (80%) and testing (20%). In the test set, both models showed good agreement with the reference standard segmentations, similar to the agreement between two independent human readers (model versus reader: TCN kidney/liver r =0.96/0.97 and CPSA kidney r =0.98, inter-reader: TCN kidney/liver r =0.96/0.98 and CPSA kidney r =0.99). Conclusions Our study demonstrates that automated models can segment kidney and liver cysts accurately in CT scans of patients with ADPKD.

Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic kidney disorder. It is primarily caused by pathogenic variants in the PKD1 or PKD2 genes. This leads to the development of numerous kidney cysts, which can result in kidney enlargement and progression to kidney failure. Pain is a common symptom in ADPKD and can negatively affect quality of life (QOL). This pain is often due to the continuous growth of kidney and liver cysts or associated cystic complications. We present a case of a 29-year-old woman with ADPKD who experienced chronic, refractory right-sided flank pain that significantly affected her QOL. Her pain persisted despite taking daily multimodal analgesics and undergoing multiple invasive interventions. She had an unusual asymmetric disease with the right kidney accounting for only 24% of her kidney function. After exhausting all other pain control strategies, she underwent right nephrectomy and partial hepatectomy, which led to substantial improvement in pain and QOL. This review describes the causes, manifestations, and management strategies for abdominal and/or flank pain in ADPKD, including a practical stepwise algorithm to guide clinicians in managing pain and improve QOL of patients with ADPKD. Pain in ADPKD can either be acute or chronic and can lead to significant physical and psychologic distress. Effective pain management in ADPKD requires a multidisciplinary approach, incorporating both nonpharmacologic and pharmacologic interventions such as gabapentin or tolvaptan in select cases. Interventions considered in ADPKD pain control include cyst aspiration with sclerotherapy, celiac plexus blockade, spinal cord stimulation, renal denervation, or nephrectomy.

ABSTRACT Background This medical center migrated from alcohol to sotradecol foam sclerotherapy (SFS) because of perceived improved efficacy in managing symptomatic kidney and liver cysts. We report technical aspects, change in short- and long-term cyst volumes, patient-reported outcomes, safety and applications of the technique. Methods In this retrospective observational study, cases from January 2017 to December 2021 had TKCV/TLCV (per Targeted Kidney or Liver or Cyst analysis) segmented using a deep-learning algorithm and cyst segmentation software (pre-, post-procedure and longitudinally). TKCV/TLCV % change were evaluated using the one-sample Wilcoxon signed rank test. For analyses involving changes in cyst volumes, the median % change in cyst volume per patient was assessed. Longitudinal changes in cyst volumes were assessed using linear mixed models. Changes in quality of life (QOL) [Linear Analog Self-Assessment (LASA), Polycystic Liver Disease Quality of life Questionnaire (PLD-Q) and 12-item short-form (SF12)] were also assessed. Results There were 102 SFS sessions (38 kidney, 58 liver, 6 combined liver/kidney cysts) performed on 77 unique individuals included for analysis. Median [interquartile range (IQR)] % reductions in TKCV were –92.0% (IQR –98.2%, –82.7%, P &lt; .001) and for TLCV were –83.1% (IQR –93.5%, –52.9%, P &lt; .001). Among patients with multiple kidney procedures (n = 7), median % reduction in TKCV was –94.3% (IQR –96.6%, –92.4%, P = .023). For patients with multiple liver procedures (n = 11), median % reduction in TLCV was –63.3% (IQR –85.2%, –28.3%, P = .004). Results were similar among the four patients undergoing multi-stage procedures (n = 1 kidney, n = 3 liver). When measured longitudinally, both liver and kidney cyst volumes declined to levels near 0 mL by 1 year follow-up and remained stable several years later. LASA physical domain and PLD-Q QOL scores improved post-SFS procedure. Conclusion SFS led to substantial long-term reductions in TKCV/TLCV and improved QOL. SFS can augment cyst volume reduction in addition to tolvaptan (kidney cysts) and octreotide (liver cysts). In some individuals with large symptomatic cysts, multiple SFS procedures were safe and effective in reducing TLCV/TKCV and improving symptoms.

ABSTRACT Background and hypothesis Podocytopathy associated with likely pathogenic/pathogenic variants of Transient receptor potential cation channel subfamily C member 6 (TRPC6) (TRPC6-AP) has been recognized for about 20 years. As a result of its rarity however, the spectrum of clinical phenotypes and genotype–phenotype correlation of TRPC6-AP remains poorly understood. Here, we characterized clinical, histological and genetic correlates of familial and sporadic patients with TRPC6-AP. Methods In this multicentre observational study, an online questionnaire followed by a systematic literature review was performed to create a cohort with comprehensive data on genetic and clinical outcomes [age of onset, clinical presentation, treatment response, kidney biopsy findings and progression to kidney failure (KF)]. Logistic regression, Cox proportional hazards model and Kaplan–Meier analyses investigated the associations between genetic variants and disease progression. Results Among 87 families (96 familial and 45 sporadic cases), 31 distinct missense TRPC6 variants (including 2 novel) were identified, with c.2683C&gt;T p.(Arg895Cys) and c.523C&gt;T p.(Arg175Trp) the commonest variants. Proteinuric kidney disease/nephrotic syndrome was the most common clinical presentation (83.7%), while focal segmental glomerulosclerosis was the most common histological finding (89.4%). By 33 (interquartile range 17–40) years, 48.9% (69/141) of patients had progressed to KF. Sporadic TRPC6-AP demonstrated an earlier progression to KF than familial cases (P = .001) and were more likely to present with nephrotic syndrome [odds ratio 4.34 (1.85–10.15); P = .001]. Gain-of-function TRPC6 variants were more frequent in familial than sporadic TRPC6-AP (70.8% vs 44.4%; P = .004). Compared with patients with other TRPC6 variants, patients with TRPC6 p.R175W and p.R895C variants progressed to KF earlier [median kidney survival of 21 years, hazard ratio 2.985 (95% confidence interval 1.40–5.79); and 38 years, hazard ratio 1.65 (95% confidence interval 1.01–2.81), respectively, log-rank P = .005]. Conclusion Our study shows unique clinical and genetic correlations of TRPC6-AP, which may enable personalized care and promising novel therapies.

Key Points Loss-of-function ALG8 and ALG9 variants were enriched in polycystic kidney/liver groups and International Classification of Diseases–coded cystic individuals in population cohorts. The ALG8 and ALG9 kidney phenotypes were usually mild to moderate, and lower eGFR or kidney failure was rare. ALG8 pathogenic variants sometimes resulted in severe polycystic liver disease. Background Autosomal dominant polycystic kidney disease (ADPKD) is a common, inherited nephropathy often resulting in kidney failure. It is genetically heterogeneous; along with the major genes, PKD1 and PKD2 , at least eight others have been suggested. ALG8 pathogenic variants have been associated with autosomal dominant polycystic liver disease and implicated in ADPKD, while ALG9 has been suggested as an ADPKD gene, but details of the phenotypes and penetrance are unclear. Methods We screened >3900 families with cystic kidneys and/or livers using global approaches to detect ALG8 or ALG9 pathogenic variants. In addition, population cohorts with sequence data (Genomics England 100K Genomics Project, UK Biobank, and Mayo Clinic Biobank [MCBB]) were screened for ALG8 / ALG9 pathogenic variants. Results Multicenter screening of individuals with polycystic kidney and/or liver disease identified 51 (1.3%) ALG8 (7 multiplex) and 23 (0.6%) ALG9 (5 multiplex) families—frequencies that were approximately 10× and approximately 24× greater than nonpolycystic kidney disease controls. Analysis of individuals with polycystic kidney disease phenotypes in 100K Genomics Project, UK Biobank, and MCBB identified nine ALG8 (0.39%) and nine ALG9 (0.39%) families, an enriched frequency over controls. Two individuals had PKD1 and ALG8 pathogenic changes. Eighty-nine percent of individuals with ALG8 mutations with imaging in the entire MCBB had kidney cysts (50%, >10 cysts), with greater median kidney and liver cyst numbers than controls. For ALG9, 78% had kidney cysts (27%, >10 cysts). Individuals with ALG8 mutations typically had mild cystic kidneys with limited enlargement. Liver cysts were common (71%), with enlarged livers (>2L) found in 11 of 62 patients, although surgical intervention was rare. The ALG9 kidney phenotype was also of mild cystic kidneys, but enlarged livers were rare; for both genes, CKD or kidney failure were rare. Conclusions ALG8 and ALG9 are defined as cystic kidney/liver genes but with limited penetrance for lower eGFR.