ALTERATIONS IN HISTIDINE METABOLISM IS A FEATURE OF EARLY AUTOSOMAL DOMINANT POLYCYSTIC KIDNEY DISEASE (ADPKD).

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by epithelial proliferation and progressive cyst enlargement. Using a non-targeted high-resolution metabolomics approach, we analyzed biofluids from 36 ADPKD and 18 healthy controls with estimated glomerular filtration rate (eGFR) > 60 ml/min to identify features specific to ADPKD or that associate with disease severity [eGFR or height-corrected total kidney volume (htTKV)]. Multiple pathways differed between ADPKD subjects and controls, with the histidine pathway being the most highly represented. Plasma histidine, urinary N-methylhistamine, methylimidazole-acetaldehyde, and imidazole-acetaldehyde, as well as 3-methylhistidine and anserine were increased, while plasma N-acetylhistamine and urinary imidazole-acetic acid were decreased in ADPKD compared to controls. In ADPKD, urinary histidine and a histidine derivative, urocanate (a precursor of glutamate), were significantly associated. HtTKV and eGFR were inversely associated with urinary glutamine and plasma 4-imidazolone-5-propionic acid, respectively. Supernatant from cultured human ADPKD renal cystic epithelia demonstrated increased aspartate and glutamate levels at 8 and 24 hours compared to primary tubular epithelia (p < 0.001). Following exposure over 48 hours to α-fluromethylhistidine, an inhibitor of histamine production, primary human PKD1 cyst epithelia proliferation increased significantly from baseline (p < 0.01) and greater than non-cystic epithelia (p < 0.05). The histidine ammonia lyase inhibitor nitromethane reversed α-fluromethylhistidine-induced cyst epithelia proliferation indicating a role for glutamate in cyst growth. In conclusion, histidine metabolism is altered preferentially leading to glutamate production and epithelial proliferation in ADPKD and associates with disease severity.

Compliance with a Healthful Plant-Based Diet Is Associated with Kidney Function in Patients with Autosomal Dominant Polycystic Kidney Disease.

Autosomal dominant polycystic kidney disease (ADPKD) is a genetic kidney disorder with multiple cyst formation that progresses to chronic kidney disease (CKD) and end-stage kidney disease. Plant-based diets have attracted considerable attention because they may prevent CKD development. This study investigated whether adherence to a plant-based diet is associated with kidney function in patients with ADPKD. The overall plant-based diet index (PDI), healthful PDI (hPDI), and unhealthful PDI (uPDI) were calculated using dietary intake data. Among 106 ADPKD patients, 37 (34.91%) were classified as having advanced CKD (eGFR < 60 mL/min/1.73 m2). The overall PDI and hPDI were lower, but the uPDI was higher in patients with advanced CKD than in those with early CKD. The hPDI was negatively correlated with the neutrophil-to-lymphocyte ratio and platelet-to-lymphocyte ratio. Moreover, the hPDI was inversely associated with advanced CKD [odds ratio (OR): 0.117 (95% confidence interval (CI): 0.039-0.351), p < 0.001], and the uPDI was positively associated with advanced CKD [OR: 8.450 (95% CI: 2.810-25.409), p < 0.001]. The findings of the current study demonstrate that greater adherence to a healthful plant-based diet is associated with improved kidney function in ADPKD patients.

Improved predictions of total kidney volume growth rate in ADPKD using two-parameter least squares fitting.

Mayo Imaging Classification (MIC) for predicting future kidney growth in autosomal dominant polycystic kidney disease (ADPKD) patients is calculated from a single MRI/CT scan assuming exponential kidney volume growth and height-adjusted total kidney volume at birth to be 150 mL/m. However, when multiple scans are available, how this information should be combined to improve prediction accuracy is unclear. Herein, we studied ADPKD subjects ( n = 36 ) with 8+ years imaging follow-up (mean = 11 years) to establish ground truth kidney growth trajectory. MIC annual kidney growth rate predictions were compared to ground truth as well as 1- and 2-parameter least squares fitting. The annualized mean absolute error in MIC for predicting total kidney volume growth rate was 2.1 % ± 2 % compared to 1.1 % ± 1 % ( p = 0.002 ) for a 2-parameter fit to the same exponential growth curve used for MIC when 4 measurements were available or 1.4 % ± 1 % ( p = 0.01 ) with 3 measurements averaging together with MIC. On univariate analysis, male sex ( p = 0.05 ) and PKD2 mutation ( p = 0.04 ) were associated with poorer MIC performance. In ADPKD patients with 3 or more CT/MRI scans, 2-parameter least squares fitting predicted kidney volume growth rate better than MIC, especially in males and with PKD2 mutations where MIC was less accurate.

Measured and Estimated Glomerular Filtration Rate to Evaluate Rapid Progression and Changes over Time in Autosomal Polycystic Kidney Disease: Potential Impact on Therapeutic Decision-Making.

Autosomal polycystic kidney disease (ADPKD) is the most common genetic form of kidney failure, reflecting unmet needs in management. Prescription of the only approved treatment (tolvaptan) is limited to persons with rapidly progressing ADPKD. Rapid progression may be diagnosed by assessing glomerular filtration rate (GFR) decline, usually estimated (eGFR) from equations based on serum creatinine (eGFRcr) or cystatin-C (eGFRcys). We have assessed the concordance between eGFR decline and identification of rapid progression (rapid eGFR loss), and measured GFR (mGFR) declines (rapid mGFR loss) using iohexol clearance in 140 adults with ADPKD with ≥3 mGFR and eGFRcr assessments, of which 97 also had eGFRcys assessments. The agreement between mGFR and eGFR decline was poor: mean concordance correlation coefficients (CCCs) between the method declines were low (0.661, range 0.628 to 0.713), and Bland and Altman limits of agreement between eGFR and mGFR declines were wide. CCC was lower for eGFRcys. From a practical point of view, creatinine-based formulas failed to detect rapid mGFR loss (-3 mL/min/y or faster) in around 37% of the cases. Moreover, formulas falsely indicated around 40% of the cases with moderate or stable decline as rapid progressors. The reliability of formulas in detecting real mGFR decline was lower in the non-rapid-progressors group with respect to that in rapid-progressor patients. The performance of eGFRcys and eGFRcr-cys equations was even worse. In conclusion, eGFR decline may misrepresent mGFR decline in ADPKD in a significant percentage of patients, potentially misclassifying them as progressors or non-progressors and impacting decisions of initiation of tolvaptan therapy.

Juxtaglomerular apparatus-mediated homeostatic mechanisms: therapeutic implication for chronic kidney disease.

INTRODUCTION: Juxtaglomerular apparatus (JGA)-mediated homeostatic mechanism links to how sodium-glucose cotransporter 2 inhibitors (SGLT2is) slow progression of chronic kidney disease (CKD) and may link to how tolvaptan slows renal function decline in autosomal dominant polycystic kidney disease (ADPKD). AREA COVERED: JGA-mediated homeostatic mechanism has been hypothesized based on investigations of tubuloglomerular feedback and renin-angiotensin system. We reviewed clinical trials of SGLT2is and tolvaptan to assess the relationship between this mechanism and these drugs. EXPERT OPINION: When sodium load to macula densa (MD) increases, MD increases adenosine production, constricting afferent arteriole (Af-art) and protecting glomeruli. Concurrently, MD signaling suppresses renin secretion, increases urinary sodium excretion, and counterbalances reduced sodium filtration. However, when there is marked increase in sodium load per-nephron, as in advanced CKD, MD adenosine production increases, relaxing Af-art and maintaining sodium homeostasis at the expense of glomeruli. The beneficial effects of tolvaptan on renal function in ADPKD may also depend on the JGA-mediated homeostatic mechanisms since tolvaptan inhibits sodium reabsorption in the thick ascending limb.The JGA-mediated homeostatic mechanism regulates Af-arts, constricting to relaxing according to homeostatic needs. Understanding this mechanism may contribute to the development of pharmacotherapeutic compounds and better care for patients with CKD.

The utility of serum neutrophil gelatinase-associated lipocalin level on predicting autosomal dominant polycystic kidney disease progression.

INTRODUCTION: We focused on neutrophil gelatinase-associated lipocalin (NGAL) and autosomal dominant polycystic kidney disease (ADPKD) progression. METHODS: ADPKD patients with an estimated glomerular filtration rate (eGFR) ≥ 30 mL/min/1.73 m2 were included. Serum NGAL level and NGAL to eGFR ratio (NGR), height-adjusted total kidney volume (hTKV) were assessed initially. Patients were followed-up for 5 years. RESULTS: Sixty one patients were enrolled and initial eGFR was 73.6 (48.9-101.5) ml/min/1.73m2. EGFR declined by 3.7 mL/min/1.73m2 per year. Thirty four patients (55.7%) exhibited rapid progression. Rapid progression group had lower serum NGAL levels (p < 0.001) and higher hTKV (p < 0.001). Lower serum NGAL level was a risk factor for rapid progression (p < 0.001). NGR was not associated with rapid progression. Serum NGAL level was predictive in for rapid progression ROC analysis (cut-off <10.62 ng/mL). CONCLUSION: Relatively lower serum NGAL levels can predict worse outcomes in ADPKD and can provide risk stratification in patients with ADPKD.

Investigational agents for autosomal dominant polycystic kidney disease: preclinical and early phase study insights.

INTRODUCTION: Autosomal Dominant Polycystic Kidney Disease (ADPKD) is the most common inherited kidney condition caused by a single-gene mutation. It leads patients to kidney failure in more than 50% of cases by the age of 60, and, given the dominant inheritance, this disease is present in the family history in more than 90% of cases. AREAS COVERED: This review aims to analyze the set of preclinical and early-phase studies to provide a general view of the current progress on ADPKD therapeutic options. Articles from PubMed and the current status of the trials listed in clinicaltrials.gov were examined for the review. EXPERT OPINION: Many potential therapeutic targets are currently under study for the treatment of ADPKD. A few drugs have reached the clinical phase, while many are currently still in the preclinical phase. Organoids could be a novel approach to the study of drugs in this phase. Other than pharmacological options, very important developing approaches are represented by gene therapy and the use of MiRNA inhibitors.

Validation of the Mayo Imaging Classification System for Predicting Kidney Outcomes in ADPKD.

BACKGROUND: The Mayo Imaging Classification was developed to predict the rate of disease progression in patients with autosomal dominant polycystic kidney disease. This study aimed to validate its ability to predict kidney outcomes in a large multicenter autosomal dominant polycystic kidney disease cohort. METHODS: Included were patients with ≥1 height-adjusted total kidney volume (HtTKV) measurement and ≥3 eGFR values during ≥1-year follow-up. Mayo HtTKV class stability, kidney growth rates, and eGFR decline rates were calculated. The observed eGFR decline was compared with predictions from the Mayo Clinic future eGFR equation. The future eGFR prediction equation was also tested for nonlinear eGFR decline. Kaplan-Meier survival analysis and Cox regression models were used to assess time to kidney failure using Mayo HtTKV class as a predictor variable. RESULTS: We analyzed 618 patients with a mean age of 47±11 years and mean eGFR of 64±25 ml/min per 1.73 m 2 at baseline. Most patients (82%) remained in their baseline Mayo HtTKV class. During a mean follow-up of 5.1±2.2 years, the mean total kidney volume growth rates and eGFR decline were 5.33%±3.90%/yr and -3.31±2.53 ml/min per 1.73 m 2 per year, respectively. Kidney growth and eGFR decline showed considerable overlap between the classes. The observed annual eGFR decline was not significantly different from the predicted values for classes 1A, 1B, 1C, and 1D but significantly slower for class 1E. This was also observed in patients aged younger than 40 years and older than 60 years and those with PKD2 mutations. A polynomial model allowing nonlinear eGFR decline provided more accurate slope predictions. Ninety-seven patients (16%) developed kidney failure during follow-up. The classification predicted the development of kidney failure, although the sensitivity and positive predictive values were limited. CONCLUSIONS: The Mayo Imaging Classification demonstrated acceptable stability and generally predicted kidney failure and eGFR decline rate. However, there was marked interindividual variability in the rate of disease progression within each class.

PKD1 Truncating Mutations Accelerate eGFR Decline in Autosomal Dominant Polycystic Kidney Disease Patients.

INTRODUCTION: Autosomal dominant polycystic kidney disease (ADPKD) is a monogenic disease characterized by the accumulation of fluid-filled cysts in the kidneys, leading to renal volume enlargement and progressive kidney function impairment. Disease severity, though, may vary due to allelic and genetic heterogeneity. This study aimed to determine genotype-phenotype correlations between PKD1 truncating and non-truncating mutations and kidney function decline in ADPKD patients. METHODS: We established a single-center retrospective cohort study in Kuwait where we followed every patient with a confirmed PKD1-ADPKD diagnosis clinically and genetically. Renal function tests were performed annually. We fitted generalized additive mixed effects models with random intercepts for each individual to analyze repeated measures of kidney function across mutation type. We then calculated survival time to kidney failure in a cox proportional hazards model. Models were adjusted for sex, age at visit, and birth year. RESULTS: The study included 22 truncating and 20 non-truncating (42 total) patients followed for an average of 6.6 years (range: 1-12 years). Those with PKD1 truncating mutations had a more rapid rate of eGFR decline (-4.7 mL/min/1.73 m2 per year; 95% CI: -5.0, -4.4) compared to patients with PKD1 non-truncating mutations (-3.5 mL/min/1.73 m2 per year; 95% CI: -4.0, -3.1) (p for interaction <0.001). Kaplan-Meier survival analysis of time to kidney failure showed that patients with PKD1 truncating mutations had a shorter renal survival time (median 51 years) compared to those with non-truncating mutations (median 56 years) (P for log-rank = 0.008). CONCLUSION: In longitudinal and survival analyses, patients with PKD1 truncating mutations showed a faster decline in kidney function compared to patients PKD1 non-truncating mutations. Early identification of patients with PKD1 truncating mutations can, at best, inform early clinical interventions or, at least, help suggest aggressive monitoring.

The effect of autosomal dominant polycystic kidney disease on mucociliary clearance.

PURPOSE: Autosomal dominant polycystic kidney disease (ADPKD) is a renal disease with genetic transmisson. Mutations in the PKD1 and PKD2 genes, which encode integral membrane proteins of the cilia of primary renal tubule epithelial cells, are seen in ADPKD. The aim of this study was to evaluate the sinonasal epithelium, which is epithelium with cilia, by measuring the nasal mucociliary clearance time, and to investigate the effect of ADPKD on nasal mucociliary clearance. METHODS: The study included 34 patients, selected from patients followed up in the Nephrology Clinic, and 34 age and gender-matched control group subjects. The nasal mucociliary clearance time (NMCT) was measured with the saccharin test. RESULTS: The mean age of the study subjects was 47.15 ± 14.16 years in the patient group and 47.65 ± 13.85 years in the control group. The eGFR rate was determined as mean 72.06 ± 34.26 mL/min in the patient group and 99.79 ± 17.22 mL/min in the control group (p < 0.001). The NMCT was determined to be statistically significantly longer in the patient group (903.6 ± 487.8 s) than in the control group (580 ± 259 s) (p = 0.006). CONCLUSIONS: The study results showed that the NMCT was statistically significantly longer in patients with ADPKD compared to the control group, but in the linear regression analysis results, no correlation was determined between eGFR and NMCT.

Metabolic reprogramming in a slowly developing orthologous model of polycystic kidney disease.

Autosomal dominant polycystic kidney disease (ADPKD) is the most common inherited kidney disease and affects 1 in 1,000 individuals. There is accumulating evidence suggesting that there are shared cellular mechanisms responsible for cystogenesis in human and murine PKD and that reprogramming of metabolism is a key disease feature. In this study, we used a targeted metabolomics approach in an orthologous mouse model of PKD (Pkd1RC/RC) to investigate the metabolic modifications a cystic kidney undergoes during disease progression. Using the Kyoto Encyclopedia of Genes and Genomes pathway database, we identified several biologically relevant metabolic pathways that were altered early in this disease (in 3-mo-old Pkd1RC/RC mice), the most highly represented being arginine biosynthesis and metabolism and tryptophan and phenylalanine metabolism. During the next 6 mo of disease progression, multiple uremic solutes accumulated in the kidney of cystic mice, including several established markers of oxidative stress and endothelial dysfunction (allantoin, asymmetric dimethylarginine, homocysteine, malondialdehyde, methionine sulfoxide, and S-adenosylhomocysteine). Levels of kynurenines and polyamines were also augmented in kidneys of Pkd1RC/RC versus wild-type mice, as were the levels of bacteria-produced indoles, whose increase within PKD kidneys suggests microbial dysbiosis. In summary, we confirmed previously published and identified novel metabolic markers and pathways of PKD progression that may prove helpful for diagnosis and monitoring of cystic kidney disease in patients. Furthermore, they provide targets for novel therapeutic approaches that deserve further study and hint toward currently understudied pathomechanisms.NEW & NOTEWORTHY This report delineates the evolution of metabolic changes occurring during autosomal dominant polycystic kidney disease (ADPKD) progression. Using an orthologous model, we performed kidney metabolomics and confirmed dysregulation of metabolic pathways previously found altered in nonorthologous or rapidly-progressive PKD models. Importantly, we identified novel alterations, including augmentation of kynurenines, polyamines, and indoles, suggesting increased inflammation and microbial dysbiosis that provide insights into PKD pathomechanisms and may prove helpful for diagnosing, monitoring, and treating ADPKD.

Curcumin Therapy to Treat Vascular Dysfunction in Children and Young Adults with ADPKD: A Randomized Controlled Trial.

BACKGROUND AND OBJECTIVES: Clinical manifestations of autosomal dominant polycystic kidney disease (ADPKD), including evidence of vascular dysfunction, can begin in childhood. Curcumin is a polyphenol found in turmeric that reduces vascular dysfunction in rodent models and humans without ADPKD. It also slows kidney cystic progression in a murine model of ADPKD. We hypothesized that oral curcumin therapy would reduce vascular endothelial dysfunction and arterial stiffness in children/young adults with ADPKD. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: In a randomized, placebo-controlled, double-blind trial, 68 children/young adults 6-25 years of age with ADPKD and eGFR>80 ml/min per 1.73 m2 were randomized to either curcumin supplementation (25 mg/kg body weight per day) or placebo administered in powder form for 12 months. The coprimary outcomes were brachial artery flow-mediated dilation and aortic pulse-wave velocity. We also assessed change in circulating/urine biomarkers of oxidative stress/inflammation and kidney growth (height-adjusted total kidney volume) by magnetic resonance imaging. In a subgroup of participants ≥18 years, vascular oxidative stress was measured as the change in brachial artery flow-mediated dilation following an acute infusion of ascorbic acid. RESULTS: Enrolled participants were 18±5 (mean ± SD) years, 54% were girls, baseline brachial artery flow-mediated dilation was 9.3±4.1% change, and baseline aortic pulse-wave velocity was 512±94 cm/s. Fifty-seven participants completed the trial. Neither coprimary end point changed with curcumin (estimated change [95% confidence interval] for brachial artery flow-mediated dilation [percentage change]: curcumin: 1.14; 95% confidence interval, -0.84 to 3.13; placebo: 0.33; 95% confidence interval, -1.34 to 2.00; estimated difference for change: 0.81; 95% confidence interval, -1.21 to 2.84; P=0.48; aortic pulse-wave velocity [centimeters per second]: curcumin: 0.6; 95% confidence interval, -25.7 to 26.9; placebo: 6.5; 95% confidence interval, -20.4 to 33.5; estimated difference for change: -5.9; 95% confidence interval, -35.8 to 24.0; P=0.67; intent to treat). There was no curcumin-specific reduction in vascular oxidative stress or changes in mechanistic biomarkers. Height-adjusted total kidney volume also did not change as compared with placebo. CONCLUSIONS: Curcumin supplementation does not improve vascular function or slow kidney growth in children/young adults with ADPKD. CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER: Curcumin Therapy to Treat Vascular Dysfunction in Children and Young Adults with ADPKD, NCT02494141. PODCAST: This article contains a podcast at https://www.asn-online.org/media/podcast/CJASN/2022_02_07_CJN08950621.mp3.

Metformin improves relevant disease parameters in an autosomal dominant polycystic kidney disease mouse model.

Autosomal dominant polycystic kidney disease (ADPKD), caused by mutations in the polycystin 1 (PKD1) or polycystin 2 genes, presents with progressive development of kidney cysts and eventual end-stage kidney disease with limited treatment options. Previous work has shown that metformin reduces cyst growth in rapid ADPKD mouse models via inhibition of cystic fibrosis transmembrane conductance regulator-mediated fluid secretion, mammalian target of rapamycin, and cAMP pathways. The present study importantly tested the effectiveness of metformin as a therapy for ADPKD in a more clinically relevant Pkd1RC/RC mouse model, homozygous for the R3277C knockin point mutation in the Pkd1 gene. This mutation causes ADPKD in humans. Pkd1RC/RC male and female mice, which have a slow progression to end-stage kidney disease, received metformin (300 mg/kg/day in drinking water vs. water alone) from 3 to 9 or 12 mo of age. As previously reported, Pkd1RC/RC females had a more severe disease phenotype as compared with males. Metformin treatment reduced the ratio of total kidney weight-to-body weight relative to age-matched and sex-matched untreated controls at both 9 and 12 mo and reduced the cystic index in females at 9 mo. Metformin also increased glomerular filtration rate, lowered systolic blood pressure, improved anemia, and lowered blood urea nitrogen levels relative to controls in both sexes. Moreover, metformin reduced gene expression of key inflammatory markers and both gene and protein expression of kidney injury marker-1 and cyclin-dependent kinase-1 versus untreated controls. Altogether, these findings suggest several beneficial effects of metformin in this highly relevant slowly progressive ADPKD mouse model, which may help inform new ADPKD therapies in patients.NEW & NOTEWORTHY Metformin treatment improved ADPKD disease severity in a relevant, slowly progressive ADPKD mouse model that recapitulates a PKD-associated PKD1 mutation. Relative to controls, metformin reduced kidney weight/body weight, cystic index and BUN levels, while improving GFR, blood pressure and anemia. Metformin also reduced key inflammatory and injury markers, along with cell proliferation markers. These findings suggest several beneficial effects of metformin in this ADPKD mouse model, which may help inform new ADPKD therapies in patients.

Recent advances in understanding ion transport mechanisms in polycystic kidney disease.

This review focuses on the most recent advances in the understanding of the electrolyte transport-related mechanisms important for the development of severe inherited renal disorders, autosomal dominant (AD) and recessive (AR) forms of polycystic kidney disease (PKD). We provide here a basic overview of the origins and clinical aspects of ARPKD and ADPKD and discuss the implications of electrolyte transport in cystogenesis. Special attention is devoted to intracellular calcium handling by the cystic cells, with a focus on polycystins and fibrocystin, as well as other calcium level regulators, such as transient receptor potential vanilloid type 4 (TRPV4) channels, ciliary machinery, and purinergic receptor remodeling. Sodium transport is reviewed with a focus on the epithelial sodium channel (ENaC), and the role of chloride-dependent fluid secretion in cystic fluid accumulation is discussed. In addition, we highlight the emerging promising concepts in the field, such as potassium transport, and suggest some new avenues for research related to electrolyte handling.

Screening of QTc interval and global autonomic activity in autosomal dominant polycystic kidney disease and atherosclerotic renal artery stenosis hypertensive patients.

OBJECTIVE: Arterial hypertension (AH) represents a major risk factor for cardiovascular disease and is associated to several complications, such as prolonged corrected QT (QTc) interval and impaired heart rate variability (HRV). Secondary causes of AH include autosomal dominant polycystic kidney disease (ADPKD) and atherosclerotic renal artery stenosis (ARAS), both known to be related to arrhythmic risk and autonomic imbalance. The aim of the study is to evaluate whether global autonomic activity and QTc interval differently affect ADPKD and ARAS hypertensive patients. PATIENTS AND METHODS: An observational study was performed on 59 patients: 16 ADPKD patients and 19 diagnosed with ARAS, compared to 24 healthy controls (HC). All patients underwent clinical evaluation, biochemical lab tests, 24-hour electrocardiogram (ECG) and renal Doppler ultrasound. HRV was assessed through the analysis of 24-hour ECG to detect standard deviation of normal-to-normal RR intervals (SDNN). QTc interval was defined as prolonged when > 440 msec. RESULTS: SDNN was significantly lower in ADPKD and ARAS patients than HC (p < 0.0001) and no significant differences were found between ADPKD and ARAS patients (p > 0.05). QTc was found significantly higher in ARAS patients than HC (p = 0.001) and in ARAS patients than ADPKD patients (p = 0.004). CONCLUSIONS: The pathogenesis of hypertension in ADPKD and ARAS patients is related to the activation of the renin angiotensin aldosterone system (RAAS). In ADPKD, cyst enlargement leads to kidney ischemia and renin release, associated to endothelial dysfunction, low nitric oxide and sympathetic tone activation. Differently, reduction in renal perfusion pressure activates RAAS and renal adrenergic nerves in ARAS patients. We can speculate that prolonged QTc interval is more present in ARAS vs. ADPKD hypertensive patients due to a greater activation of RAAS. We suggest adding 24-hour HRV evaluation in association with traditional risk factors in course of ADPKD and ARAS hypertension to better stratify cardiovascular risk in these groups of patients.

Metabolic derangement in polycystic kidney disease mouse models is ameliorated by mitochondrial-targeted antioxidants.

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by progressively enlarging cysts. Here we elucidate the interplay between oxidative stress, mitochondrial dysfunction, and metabolic derangement using two mouse models of PKD1 mutation, PKD1RC/null and PKD1RC/RC. Mouse kidneys with PKD1 mutation have decreased mitochondrial complexes activity. Targeted proteomics analysis shows a significant decrease in proteins involved in the TCA cycle, fatty acid oxidation (FAO), respiratory complexes, and endogenous antioxidants. Overexpressing mitochondrial-targeted catalase (mCAT) using adeno-associated virus reduces mitochondrial ROS, oxidative damage, ameliorates the progression of PKD and partially restores expression of proteins involved in FAO and the TCA cycle. In human ADPKD cells, inducing mitochondrial ROS increased ERK1/2 phosphorylation and decreased AMPK phosphorylation, whereas the converse was observed with increased scavenging of ROS in the mitochondria. Treatment with the mitochondrial protective peptide, SS31, recapitulates the beneficial effects of mCAT, supporting its potential application as a novel therapeutic for ADPKD.

A radiomics method based on MR FS-T2WI sequence for diagnosing of autosomal dominant polycystic kidney disease progression.

OBJECTIVE: We aimed to construct/validate a radiomics method based on MR FS-T2WI sequence for the evaluation of kidney function in patients with autosomal dominant polycystic kidney disease (ADPKD). PATIENTS AND METHODS: The clinical data and MRI images of 114 patients with ADPKD were retrospectively analyzed. With a glomerular filtration rate of 60 mL/min per 1.73 m2 as the cutoff value, patients were divided into two groups, where there were 59 patients with GFR ≥60 mL/min per 1.73 m2 (including CKD1 and CKD2 phase) and 55 patients with GFR <60 mL/min per 1.73 m2 (including CKD3 phase and higher). All patients underwent the 3.0T MR scan of the kidney. Then, the kidney were delineated layer by layer based on the FS-T2WI sequence to obtain the volume of interest (VOI) for radiomics features extraction. The optimal radiomics features were selected by least absolute shrinkage and selection operator (LASSO). Three kinds of data modality including the pure clinical data, the pure image data and the clinical-image fused data were utilized to establish three types of models (clinical, image and with their combination) separately by five machine learning classifiers: k-nearest-neighbors (KNN), support vector machine (SVM), logistic regression (LR), random forests (RF) and multi-layer perception (MLP). Receiver operating characteristic (ROC) curve, areas under the curve (AUC), sensitivity, specificity and precision were employed to evaluate the model's effectiveness to diagnosis the glomerular filtration rate of patients with ADPKD based on different models. Besides, Delong test was applied to compare ROCs between models. RESULTS: 960 radiomics features were extracted from each VOIs, and clinical information included the gender and age of each patient. After feature selection, 23 and 21 features based on pure image data and clinical-image fused data were independently used to construct models for the kidney function evaluation. The clinical-image fused model (AUC=0.89) has better performance than the pure image model (p=0.046) and pure clinical model (p<0.001). Clinical-image fused model based on LR classifier showed the best diagnostic efficiency, with AUC=0.89, sensitivity=0.8867 and specificity=0.7959. CONCLUSIONS: The MR FS-T2WI radiomics analysis based on clinical-image fused model is instrumental in evaluating and predicting the kidney function of patients with polycystic kidney disease.

The effect of trichlormethiazide in autosomal dominant polycystic kidney disease patients receiving tolvaptan: a randomized crossover controlled trial.

The vasopressin V2 receptor antagonist tolvaptan delays the progression of autosomal dominant polycystic kidney disease (ADPKD). However, some patients discontinue tolvaptan because of severe adverse aquaretic events. This open-label, randomized, controlled, counterbalanced, crossover trial investigated the effects of trichlormethiazide, a thiazide diuretic, in patients with ADPKD receiving tolvaptan (n = 10) who randomly received antihypertensive therapy with or without trichlormethiazide for 12 weeks. The primary and secondary outcomes included amount and osmolarity of 24-h urine and health-related quality-of-life (HRQOL) parameters assessed by the Kidney Disease Quality of Life-Short Form questionnaire, renal function slope, and plasma/urinary biomarkers associated with disease progression. There was a significant reduction in urine volume (3348 ± 584 vs. 4255 ± 739 mL; P < 0.001) and a significant increase in urinary osmolarity (182.5 ± 38.1 vs. 141.5 ± 38.1 mOsm; P = 0.001) in patients treated with trichlormethiazide. Moreover, trichlormethiazide improved the following HRQOL subscales: effects of kidney disease, sleep, emotional role functioning, social functioning, and role/social component summary. No significant differences were noted in renal function slope or plasma/urinary biomarkers between patients treated with and without trichlormethiazide. In patients with ADPKD treated with tolvaptan, trichlormethiazide may improve tolvaptan tolerability and HRQOL parameters.

Predicting Future Renal Function Decline in Patients with Autosomal Dominant Polycystic Kidney Disease Using Mayo Clinic Classification.

INTRODUCTION: Mayo clinic classification (MCC) has been proposed in patients with autosomal dominant polycystic kidney disease (ADPKD) to identify who may experience a rapid decline of renal function. Our aim was to validate this predictive model in a population from southern Spain. METHODS: ADPKD patients with measurements of height-adjusted total kidney volume (HtTKV) and baseline estimated glomerular filtration rate (eGFR) >30 mL/min/1.73 m2 were selected. Last eGFR was estimated with Mayo Clinic (MC) equation and bias and accuracy were studied. We also analyzed predictive capacity of MCC classes using survival analysis and Cox regression models. RESULTS: We included 134 patients with a mean follow-up of 82 months. While baseline eGFR was not different between classes, last eGFR decreased significantly with them. eGFR variation rate was different according to the MCC class with a more rapid decline in 1C, 1D, and 1E classes. Final eGFR predicted was not significantly different from the real one, with an absolute bias of 0.6 ± 17.0 mL/min/1.73 m2. P10 accuracy was low ranging from 37.5 to 59.5% in classes 1C, 1D, and 1E. Using MC equation, the rate of eGFR decline was underestimated in 1C, 1D, and 1E classes. Cox regression analysis showed that MCC class is a predictor of renal survival after adjusting with baseline eGFR, age, sex, and HtTKV, with 1D and 1E classes having the worst prognosis. CONCLUSION: MCC classification is able to identify patients who will undergo a more rapid decline of renal function in a Spanish population. Prediction of future eGFR with MC equation is acceptable as a group, although it shows a loss of accuracy considering individual values. The rate of eGFR decline calculated using MC equation can underestimate the real rate presented by patients of 1C, 1D, and 1E classes.