HYDROchlorothiazide versus placebo to PROTECT polycystic kidney disease patients and improve their quality of life: study protocol and rationale for the HYDRO-PROTECT randomized controlled trial

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) leads to progressive renal cyst formation and loss of kidney function in most patients. Vasopressin 2 receptor antagonists (V2RA) like tolvaptan are currently the only available renoprotective agents for rapidly progressive ADPKD. However, aquaretic side effects substantially limit their tolerability and therapeutic potential. In a preliminary clinical study, the addition of hydrochlorothiazide (HCT) to tolvaptan decreased 24-h urinary volume and appeared to increase renoprotective efficacy. The HYDRO-PROTECT study will investigate the long-term effect of co-treatment with HCT on tolvaptan efficacy (rate of kidney function decline) and tolerability (aquaresis and quality of life) in patients with ADPKD.

METHODS

The HYDRO-PROTECT study is an investigator-initiated, multicenter, double-blind, placebo-controlled, randomized clinical trial. The study is powered to enroll 300 rapidly progressive patients with ADPKD aged ≥ 18 years, with an eGFR of > 25 mL/min/1.73 m2, and on stable treatment with the highest tolerated dose of tolvaptan in routine clinical care. Patients will be randomly assigned (1:1) to daily oral HCT 25 mg or matching placebo treatment for 156 weeks, in addition to standard care.

OUTCOMES

The primary study outcome is the rate of kidney function decline (expressed as eGFR slope, in mL/min/1.73 m2 per year) in HCT versus placebo-treated patients, calculated by linear mixed model analysis using all available creatinine values from week 12 until the end of treatment. Secondary outcomes include changes in quality-of-life questionnaire scores (TIPS, ADPKD-UIS, EQ-5D-5L, SF-12) and changes in 24-h urine volume.

CONCLUSION

The HYDRO-PROTECT study will demonstrate whether co-treatment with HCT can improve the renoprotective efficacy and tolerability of tolvaptan in patients with ADPKD.

Standardized 4-point scoring scale of [18F]-FDG PET/CT imaging helps in the diagnosis of renal and hepatic cyst infections in patients with autosomal dominant polycystic kidney disease: a validation cohort

Background

Autosomal dominant polycystic kidney disease (ADPKD) is prone to multiple complications, including cyst infection (CyI). 2-Deoxy-2-[18F]fluoro-d-glucose positron emission tomography/computed tomography ([18F]-FDG PET/CT) imaging has proved useful in the diagnosis of renal and hepatic CyI. A 4-point scale comparing the uptake of [18F]-FDG in the suspected infected cyst versus the hepatic physiological background has been recently proposed. We performed an independent validation of this semi-quantitative scoring system.

Methods

All ADPKD patients hospitalized between January 2009 and November 2019 who underwent an [18F]-FDG PET/CT for suspected CyI were retrospectively identified using computer-based databases. Medical files were reviewed. CyI was conventionally defined by the combination of fever (≥38°C), abdominal pain, increased plasma C-reactive protein levels (≥70 mg/L), absence of any other cause of inflammation and favourable outcome after ≥21 days of antibiotics. [18F]-FDG uptake of the suspected CyI was evaluated using a 4-point scale comparing the uptake of [18F]-FDG around the infected cysts with the uptake in the hepatic parenchyma. Statistics were performed using SAS version 9.4.

Results

Fifty-one [18F]-FDG PET/CT scans in 51 patients were included, of which 11 were cases of CyI. The agreement between the 4-point scale and the gold-standard criteria of CyI was significant [odds ratio of 6.03 for CyI in case of a score ≥3 (P = .014)]. The corresponding sensitivity, specificity, and positive and negative predictive values of [18F]-FDG PET/CT using the 4-point scale were 64% [Clopper-Pearson 95% confidence interval (CI) 30%-89%], 78% (95% CI 62%-89%), 44% (95% CI 20%-70%) and 89% (95% CI 73%-97%), respectively.

Conclusions

Our independent validation cohort confirms the use of a semi-quantitative 4-point scoring system of [18F]-FDG PET/CT imaging in the diagnosis of CyI in patients with ADPKD. Considering its performance metrics with high specificity and negative predictive value, the scoring system is particularly useful to distinguish other causes of clinical inflammation than CyI and as such avoid unnecessarily long antibiotic treatment.

Leukopenia in autosomal dominant polycystic kidney disease: a single-center cohort of kidney transplant candidates with post-transplantation follow-up

Background

Autosomal dominant polycystic kidney disease (ADPKD) has occasionally been associated with lower peripheral white blood cell (WBC) counts. This study aimed to investigate the peripheral blood cell counts in a large cohort of kidney transplant recipients before and after kidney transplantation and its potential impact on post-transplant outcomes.

Methods

This was a retrospective study with long-term follow-up data of 2090 patients who underwent a first kidney transplantation in the Leuven University Hospitals, of whom 392 had ADPKD.

Results

In total, 2090 patients who underwent a first kidney transplantation in the Leuven University Hospitals were included, of whom 392 had ADPKD. Both pre- and post-transplantation, ADPKD patients had significantly lower total WBC counts, and more specifically lower neutrophil, lymphocyte and eosinophil counts compared with the non-ADPKD patients. This observation was independent of potential confounders such as level of inflammation, smoking habit, vitamins and pre-transplant medication. Overall survival and kidney transplant survival were significantly better in ADPKD vs non-ADPKD transplant recipients and a longer time to first infection was observed. However, no association between blood cell counts and outcome differences was found.

Conclusions

In conclusion, this large single-center study reports a strong and independent association between ADPKD and lower peripheral WBC counts both before and after kidney transplantation. Considering the role of inflammation in disease progression, further investigation into the role of WBC in ADPKD is needed.

Low agreement between various eGFR formulae in pediatric and young adult ADPKD patients

BACKGROUND

Young autosomal dominant polycystic kidney disease (ADPKD) patients are becoming the new target population for the development of new treatment options. Determination of a reliable equation for estimated glomerular filtration rate (eGFR) from early stages is needed with the promising potential interventional therapies.

METHODS

Prospective and longitudinal study on a cohort of 68 genotyped ADPKD patients (age range 0-23 years) with long-term follow-up. Commonly used equations for eGFR were compared for their relative performance.

RESULTS

The revised Schwartz formula (CKiD) showed a highly significant decline in eGFR with aging (- 3.31 mL/min/1.73 m2/year, P < 0.0001). The recently updated equation by the Schwartz group (CKiDU25) showed a smaller (- 0.90 mL/min/1.73 m2/year) but significant (P = 0.001) decline in eGFR with aging and also showed a significant sex difference (P < 0.0001), not observed by the other equations. In contrast, the full age spectrum (FAS) equations (FAS-SCr, FAS-CysC, and the combined) showed no age and sex dependency. The prevalence of hyperfiltration is highly dependent on the formula used, and the highest prevalence was observed with the CKiD Equation (35%).

CONCLUSIONS

The most widely used methods to calculate eGFR in ADPKD children (CKiD and CKiDU25 equations) were associated with unexpected age or sex differences. The FAS equations were age- and sex-independent in our cohort. Hence, the switch from the CKiD to CKD-EPI equation at the transition from pediatric to adult care causes implausible jumps in eGFR, which could be misinterpreted. Having reliable methods to calculate eGFR is indispensable for clinical follow-up and clinical trials. A higher resolution version of the Graphical abstract is available as Supplementary information.

Risk Severity Model for Pediatric Autosomal Dominant Polycystic Kidney Disease Using 3D Ultrasound Volumetry

BACKGROUND

Height-adjusted total kidney volume (htTKV) measured by imaging defined as Mayo Imaging Class (MIC) is a validated prognostic measure for autosomal dominant polycystic kidney disease (ADPKD) in adults to predict and stratify disease progression. However, no stratification tool is currently available in pediatric ADPKD. Because magnetic resonance imaging and computed tomography in children are difficult, we propose a novel 3D ultrasound-based pediatric Leuven Imaging Classification to complement the MIC.

METHODS

A prospective study cohort of 74 patients with genotyped ADPKD (37 female) was followed longitudinally with ultrasound, including 3D ultrasound, and they underwent in total 247 3D ultrasound assessments, with patients' median age (interquartile range [IQR]) at diagnosis of 3 (IQR, 0-9) years and at first 3D ultrasound evaluation of 10 (5-14) years. First, data matching was done to the published MIC classification, followed by subsequent optimization of parameters and model type.

RESULTS

PKD1 was confirmed in 70 patients (95%), PKD2 in three (4%), and glucosidase IIα unit only once (1%). Over these 247 evaluations, the median height was 143 (IQR, 122-166) cm and total kidney volume was 236 (IQR, 144-344) ml, leading to an htTKV of 161 (IQR, 117-208) ml/m. Applying the adult Mayo classification in children younger than 15 years strongly underestimated ADPKD severity, even with correction for height. We therefore optimized the model with our pediatric data and eventually validated it with data of young patients from Mayo Clinic and the Consortium for Radiologic Imaging Studies of Polycystic Kidney Disease used to establish the MIC.

CONCLUSIONS

We proposed a five-level Leuven Imaging Classification ADPKD pediatric model as a novel classification tool on the basis of patients' age and 3D ultrasound-htTKV for reliable discrimination of childhood ADPKD severity.

The emerging role of the apelinergic system in kidney physiology and disease

The apelinergic system (AS) is a novel pleiotropic system with an essential role in renal and cardiovascular physiology and disease, including water homeostasis and blood pressure regulation. It consists of two highly conserved peptide ligands, apelin and apela, and a G-protein-coupled apelin receptor. The two ligands have many isoforms and a short half-life and exert both similar and divergent effects. Vasopressin, apelin and their receptors colocalize in hypothalamic regions essential for body fluid homeostasis and interact at the central and renal levels to regulate water homeostasis and diuresis in inverse directions. In addition, the AS and renin-angiotensin system interact both systemically and in the kidney, with implications for the cardiovascular system. A role for the AS in diverse pathological states, including disorders of sodium and water balance, hypertension, heart failure, pre-eclampsia, acute kidney injury, sepsis and diabetic nephropathy, has recently been reported. Furthermore, several metabolically stable apelin analogues have been developed, with potential applications in diverse diseases. We review here what is currently known about the physiological functions of the AS, focusing on renal, cardiovascular and metabolic homeostasis, and the role of the AS in associated diseases. We also describe several hurdles and research opportunities worthy of the attention of the nephrology community.

Safety, Efficacy, and Predictors for Late Reintervention After Embolization of Renal Angiomyolipomas – Embolization renal angiomyolipoma

Purpose To retrospectively analyze the procedural and long-term clinical outcome of the selective embolization of renal angiomyolipoma. In addition, potential predictive factors for higher risk of late re-intervention were analyzed.

Methods Retrospective monocentric study, including 34 consecutive patients, analyzing the safety, efficiency, and long-term clinical outcome of catheter-directed embolization of renal AML. Additionally, the difference in postembolization renal function between patients embolized in the acute and in the elective setting was analyzed. Secondly, we also evaluated whether volume/diameter of the AML and presence of intralesional aneurysms are risk factors for late re-intervention.

Results Embolization of renal AML was performed to control volume (n = 21; 62 %) or to stop spontaneous hemorrhage (n = 13; 38 %) with angiographic success in all cases but was associated with renal abscess (n = 1) and pulmonary embolism (n = 1) without a significant difference in renal function before and after embolization (P = 0.513). Volume/diameter (P = 0.276/P = 0.21) and presence of aneurysms before embolization (P = 0.37) are not predictive for a higher risk of late re-intervention.

Conclusion Catheter-directed embolization is a safe and effective treatment modality for asymptomatic and bleeding renal AML, without a negative impact on renal function. Initial mass volume/diameter or presence/absence of intralesional aneurysms does not seem to be predictive for late re-intervention.

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Citation Format

MO011: The Use of a 4-Point Scoring Scale in 18F-FDG-PET/CT Imaging Helps for Diagnosis of Renal and Hepatic CYST Infections in Patients with Autosomal Dominant Polycystic Kidney Disease: A Validation Cohort

BACKGROUND AND AIMS

Autosomal dominant polycystic kidney disease (ADPKD) is prone to multiple complications, including cyst infection (CyI). 18F-FDG PET/CT imaging proved useful in the diagnosis of renal and hepatic CyI. A 4-point scale comparing the uptake of 18F-FDG in the suspected infected cyst versus the hepatic physiological background has been proposed. We performed an independent validation of this semi-quantitative score system.

METHOD

All ADPDK patients hospitalized between January 2007 and March 2019 who underwent an 18F-FDG PET/CT for suspected CyI were retrospectively identified using computer-based databases. Medical files were systematically reviewed. CyI was conventionally defined by: fever (&gt;38°C), abdominal pain, increased plasma CRP levels (≥70 mg/dL), absence of any other cause of inflammation and favorable outcomes after ≥21 days of antibiotics. The 18F-FDG uptake around the suspected CyI was evaluated using the 4-point scale. Stats were performed using SAS version 9.4.

RESULTS

Our cohort included 51 18F-FDG PET/CT in 51 patients, including 11 cases of CyI according to the above-detailed definition. The agreement between the 4-point scale and the gold-standard criteria of CyI was significant, with an odds ratio of 6.03 for CyI in case of a score ≥3 (P, 0.014). The corresponding sensitivity and specificity of PET/CT using the 4-point scale were 63.3% and 77.5%, respectively.

CONCLUSION

Our independent validation cohort confirms that the use of a semi-quantitative 4-point scoring system helps in the diagnosis of CyI by 18F-FDG PET/CT imaging in patients with ADPKD.

Natural History of Bone Disease following Kidney Transplantation

BACKGROUND

Knowledge of the effect of kidney transplantation on bone is limited and fragmentary. The aim of this study was to characterize the evolution of bone disease in the first post-transplant year.

METHODS

We performed a prospective, observational cohort study in patients referred for kidney transplantation under a steroid-sparing immunosuppressive protocol. Bone phenotyping was done before, or at the time of, kidney transplantation, and repeated at 12 months post-transplant. The phenotyping included bone histomorphometry, bone densitometry by dual-energy x-ray absorptiometry, and biochemical parameters of bone and mineral metabolism.

RESULTS

Paired data were obtained for 97 patients (median age 55 years; 72% male; 21% of patients had diabetes). Bone turnover remained normal or improved in the majority of patients (65%). Bone histomorphometry revealed decreases in bone resorption (eroded perimeter, mean 4.6% pre- to 2.3% post-transplant; P<0.001) and disordered bone formation (fibrosis, 27% pre- versus 2% post-transplant; P<0.001). Whereas bone mineralization was normal in all but one patient pretransplant, delayed mineralization was seen in 15% of patients at 1 year post-transplant. Hypophosphatemia was associated with deterioration in histomorphometric parameters of bone mineralization. Changes in bone mineral density were highly variable, ranging from -18% to +17% per year. Cumulative steroid dose was related to bone loss at the hip, whereas resolution of hyperparathyroidism was related to bone gain at both spine and hip.

CONCLUSIONS

Changes in bone turnover, mineralization, and volume post-transplant are related both to steroid exposure and ongoing disturbances of mineral metabolism. Optimal control of mineral metabolism may be key to improving bone quality in kidney transplant recipients.

CLINICAL TRIAL REGISTRY NAME AND REGISTRATION NUMBER

Evolution of Bone Histomorphometry and Vascular Calcification Before and After Renal Transplantation, NCT01886950.

Static histomorphometry allows for a diagnosis of bone turnover in renal osteodystrophy in the absence of tetracycline labels

A bone biopsy with prior tetracycline labeling is the gold standard to diagnose renal osteodystrophy. In cases of missing tetracycline labels, it is still paramount to gain clinically relevant information from the extracted bone sample, by evaluating the static histomorphometry. This study investigates the diagnostic performance of static histomorphometry for the evaluation of high and low bone turnover. Transiliac bone biopsies taken pre- or post- kidney transplantation, of sufficient quality for a full histomorphometric analysis were included (n = 205). The cohort was randomly split to provide separate exploration and validation subsets. Diagnostic performance was evaluated by area under the receiver operator characteristics curve (AUC). All histomorphometric parameters were significantly different across categories of low (24%), normal (60%), and high (16%) bone turnover, and all were significant predictors of both high and low bone turnover (AUC 0.71-0.84). Diagnostic performance was very good for high turnover, as a combination of static parameters resulted in negative and positive predictive values (NPV and PPV) of 80% and 96%, respectively. For low turnover, the combined model resulted in PPV of 71% and NPV of 82%. We conclude that in the absence of tetracycline labels, static histomorphometry provide an acceptable alternative for a diagnosis of bone turnover in renal osteodystrophy.

Diagnostic Accuracy of Noninvasive Bone Turnover Markers in Renal Osteodystrophy

RATIONALE & OBJECTIVE

Bone biopsy remains the gold standard for diagnosing renal osteodystrophy as comparable non-invasive alternatives have yet to be established. The aim of this study was to investigate the diagnostic accuracy of biochemical markers of skeletal remodeling to predict bone turnover.

STUDY DESIGN

Cross-sectional retrospective diagnostic test study.

SETTING & PARTICIPANTS

Patients with chronic kidney disease stages G4-G5D and kidney transplant recipients with successful transiliac bone biopsies.

TESTS COMPARED

Bone turnover as determined by bone histomorphometry was compared to the following biochemical markers: Full-length (1-84) parathyroid hormone (PTH), bone-specific alkaline phosphatase (BsAP), intact procollagen type I N-terminal propeptide (PINP), and tartrate-resistant acid phosphatase isoform 5b (TRAP5b).

OUTCOME

Diagnostic performance was evaluated by area under the receiver operator characteristics curve (AUC), sensitivity, specificity, and negative and positive predictive values. Optimal diagnostic cutoffs were determined in an exploration cohort (n=100) and validated in a separate cohort (n=99).

RESULTS

All biomarkers differed across categories of low 33 (17%), normal 109 (55%), and high 57 (29%) bone turnover. AUC values were in the range of 0.75 - 0.85. High negative predictive values (≥90%) were found for both high and low bone turnover, indicating the ability to rule out both conditions using the suggested biomarker cutoffs. The highest diagnostic performances were seen with combinations of biomarkers, with overall diagnostic accuracies of 90% for high turnover, and 78% for low turnover. Results were comparable for kidney transplant candidates and recipients in a sensitivity analysis.

LIMITATIONS

The single-center approach and heterogeneity of the study cohort are main limitations of this study.

CONCLUSIONS

We conclude that the diagnostic performance of biochemical markers of bone turnover is acceptable, with clinical utility in ruling out both high and low turnover bone disease.

AQP1 Promoter Variant, Water Transport, and Outcomes in Peritoneal Dialysis

BACKGROUND

Variability in ultrafiltration influences prescriptions and outcomes in patients with kidney failure who are treated with peritoneal dialysis. Variants in AQP1, the gene that encodes the archetypal water channel aquaporin-1, may contribute to that variability.

METHODS

We gathered clinical and genetic data from 1851 patients treated with peritoneal dialysis in seven cohorts to determine whether AQP1 variants were associated with peritoneal ultrafiltration and with a risk of the composite of death or technique failure (i.e., transfer to hemodialysis). We performed studies in cells, mouse models, and samples obtained from humans to characterize an AQP1 variant and investigate mitigation strategies.

RESULTS

The common AQP1 promoter variant rs2075574 was associated with peritoneal ultrafiltration. Carriers of the TT genotype at rs2075574 (10 to 16% of patients) had a lower mean (±SD) net ultrafiltration level than carriers of the CC genotype (35 to 47% of patients), both in the discovery phase (506±237 ml vs. 626±283 ml, P = 0.007) and in the validation phase (368±603 ml vs. 563±641 ml, P = 0.003). After a mean follow-up of 944 days, 139 of 898 patients (15%) had died and 280 (31%) had been transferred to hemodialysis. TT carriers had a higher risk of the composite of death or technique failure than CC carriers (adjusted hazard ratio, 1.70; 95% confidence interval [CI], 1.24 to 2.33; P = 0.001), as well as a higher risk of death from any cause (24% vs. 15%, P = 0.03). In mechanistic studies, the rs2075574 risk variant was associated with decreases in AQP1 promoter activity, aquaporin-1 expression, and glucose-driven osmotic water transport. The use of a colloid osmotic agent mitigated the effects of the risk variant.

CONCLUSIONS

A common variant in AQP1 was associated with decreased ultrafiltration and an increased risk of death or technique failure among patients treated with peritoneal dialysis. (Funded by the Swiss National Science Foundation and others.).

Patterns of renal osteodystrophy one year after kidney transplantation

BACKGROUND

Renal osteodystrophy is considered common, but is not well characterized, in contemporary kidney transplant recipients. This study reports extensively on bone phenotype by bone histomorphometry, bone densitometry, and novel bone biomarkers 1 year after kidney transplantation.

METHODS

A transiliac bone biopsy and dual energy x-ray absorptiometry were performed in 141 unselected kidney transplant recipients in this observational cohort study. Blood and 24 hr urine samples were collected simultaneously.

RESULTS

Median age was 57 ± 11 years, 71% were men, and all were of Caucasian ethnicity. Bone turnover was normal in 71% of patients, low in 26%, and high in just four cases (3%). Hyperparathyroidism with hypercalcemia was present in 13% of patients, of which one had high bone turnover. Delayed bone mineralization was detected in 16% of patients, who were characterized by hyperparathyroidism (137 vs. 53 ρg/mL), a higher fractional excretion of phosphate (40 vs. 32%), and lower levels of phosphate (2.68 vs 3.18 mg/dL) and calcidiol (29 vs. 37 ng/mL) compared to patients with normal bone mineralization. Osteoporosis was present in 15-46% of patients, with the highest prevalence at the distal skeleton. The proportion of osteoporotic patients was comparable across categories of bone turnover and mineralization.

CONCLUSION

The majority of kidney transplant recipients, including patients with osteoporosis, have a normal bone turnover at 1-year post-transplant. Low bone turnover is seen in a substantial subset, while high bone turnover is rare. Vitamin D deficiency and hypophosphatemia represent potential interventional targets to improve bone health post-transplant.

MO021ENHANCED MCP-1 RELEASE IN EARLY AUTOSOMAL DOMINANT POLYCYSTIC KIDNEY DISEASE

Background and Aims

Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations in either the PKD1 or PKD2 gene. While kidney failure typically occurs in adulthood, the disease starts in utero. The best change of preserving renal function long term might be the use of agents with few side effects as early as possible. For this approach, both better early prognostic stratification and novel treatment options are needed. The pediatric phase of ADPKD, while kidney function is still normal and before significant tissue destruction has occurred could be the best stage both to identify and study prognostic biomarkers as well as to identify novel targets for early treatment. Copeptin (a surrogate for vasopressin), epidermal growth factor (EGF) ( a measure for functional tubular mass) and monocyte chemoattractant protein-1 (MCP-1) ( a chemoattractant for macrophages) are associated with severity and hold prognostic value in adults but remain unstudied in the early disease stage. Kidneys from adults with ADPKD exhibit macrophage infiltration, and a prominent role of MCP-1 secretion by tubular epithelial cells is suggested from rodent models.

Method

A monocentric cross-sectional study in a tertiary referral center was performed. All consenting genotyped ADPKD patients attending the outpatient pediatric ADPKD clinic of the university hospital of Leuven and age, sex and BMI matched healthy controls were included between June and October 2017. Plasma copeptin, urinary EGF and urinary MCP-1 were evaluated. MCP-1 was studied in mouse collecting duct cells, human proximal tubular cells and fetal kidney tissue.

Results

53 genotyped ADPKD patients and 53 controls were included. Mean (SD) age was 10.4 (5.9) vs 10.5 (6.1) years (P=0.543), and eGFR 122.7 (39.8) vs 114.5 (23.1) ml/min/1.73 m2 (P= 0.177) in patients vs controls respectively. Outcome parameters in table. Plasma copeptin and EGF secretion were comparable between both groups. Median (IQR) urinary MCP-1 (pg/mg creatinine) was significantly higher in ADPKD patients (185.4 (213.8)) compared to controls (154.7 (98.0)) (P= 0.010). Human proximal tubular cells with a heterozygous PKD1 mutation and mouse collecting duct cells with a PKD1 knockout exhibited increased MCP-1 secretion triggered by fetal bovine serum. Human fetal ADPKD kidneys displayed prominent MCP-1 immunoreactivity and M2 macrophage infiltration.

Conclusion

An increase in tubular MCP-1 secretion is an early event in ADPKD, long before kidney function decline and in children with few kidney cysts. MCP-1 is a promising early disease severity marker and a potential treatment target.

MO020AUTOSOMAL DOMINANT POLYCYSTIC KIDNEY DISEASE, CYTOPENIA AND POSTTRANSPLANT OUTCOMES: A RETROSPECTIVE ANALYSIS

Background and Aims

Autosomal dominant polycystic kidney disease (ADPKD), the most common monogenetic inherited kidney disease, has been reported to be associated with distinct cytopenias. The pathophysiological mechanism behind this association and its clinical implications are unknown. Sparse and conflicting data have suggested a tendency to greater vulnerability for cancer and infections in ADPKD renal transplant recipients as compared to their non-ADPKD counterparts. Furthermore polycystin expression has been demonstrated in lymphocytes in vitro with impact on lymphocyte function. From this background, cytopenia could be hypothesized to be directly induced by the molecular PKD defects and to impact on outcome in affected patients. The main interest of the current study is to confirm the association between ADPKD and cytopenia in a well-defined clinical cohort of patients at the time of kidney transplantation. Furthermore, the impact of ADPKD and cytopenia on posttransplant outcomes is studied.

Method

Baseline (pre-transplantation) and follow-up data from all patients who underwent a first renal transplantation between 01/04/1964 and 01/09/2019 at the Leuven University Hospitals were retrieved from the renal transplantation database.

Results

4103 patients were included: 611 ADPKD and 3492 non-ADPKD. Immediately before transplantation, significant differences in total white blood cell (6.33 +/- 2.59 ADPKD versus 7.17 +/- 2.21 non-ADPKD; p&lt;0.0001), neutrophil (4.04 +/- 1.59 versus 4.54 +/- 1.88; p&lt;0.0001), lymphocyte (1.45 +/- 0.05 versus 1.57 +/- 0.68; p&lt;0.0001), basophil (0.041 +/- 0.084 versus 0.046 +/- 0.048; p&lt;0.0001), eosinophil (0.23 +/- 0.24 versus 0.29 +/- 0.33; p&lt;0.0001) and thrombocyte counts (203.00 +/- 67.21 versus 230.18 +/- 76.00; p&lt;0.0001) between ADPKD and non-ADPKD patients were observed. After multiple linear regression analysis, ADPKD remained significantly associated with total white blood cell, neutrophil, monocyte and thrombocyte counts.

In terms of post-transplant outcomes, significant univariate differences between ADPKD and non-ADPKD transplant recipients in favor of the ADPKD patients were observed for overall survival, time to first rejection and time to transplant failure. On the contrary, a significantly faster onset of the first posttransplant malignancy and infection was observed in ADPKD as compared to non-ADPKD. Furthermore, the numbers of posttransplant infections and malignancies tended to be higher in the ADPKD patient cohort, the number of transplant rejections was significantly lower. While pre-transplantation lymphopenia was univariately associated with lower overall survival, none of the other post-transplant outcomes was associated with lymphopenia, nor with any of the other blood cell counts. After multivariate Cox proportional hazard regression analysis, ADPKD remained significantly associated with time to first rejection (p=0.0310; HR 0.632) and overall survival (p&lt;0.0001; HR 0.512). None of the blood cell count variables retained significance in the multivariate outcome models.

Conclusion

This large retrospective single center study confirmed the association between cytopenia and ADPKD immediately before kidney transplantation. Furthermore, ADPKD was also associated with differences in posttransplant outcomes. In multivariate survival analysis, the impact of ADPKD on outcomes outweighed that of other variables, amongst others the blood cell counts. From this, it is tempting to speculate that ADPKD influences outcome through a disease-related impact on blood cells, however many more factors are most probably involved. The hypothesis that cytopenia could be an extra-renal manifestation of ADPKD, directly linked to its genetic basis, and its impact on outcome warrant further investigation.

Enhanced MCP-1 Release in Early Autosomal Dominant Polycystic Kidney Disease

Introduction

Autosomal dominant polycystic kidney disease (ADPKD) causes kidney failure typically in adulthood, but the disease starts in utero. Copeptin, epidermal growth factor (EGF), and monocyte chemoattractant protein-1 (MCP-1) are associated with severity and hold prognostic value in adults but remain unstudied in the early disease stage. Kidneys from adults with ADPKD exhibit macrophage infiltration, and a prominent role of MCP-1 secretion by tubular epithelial cells is suggested from rodent models.

Methods

In a cross-sectional study, plasma copeptin, urinary EGF, and urinary MCP-1 were evaluated in a pediatric ADPKD cohort and compared with age-, sex-, and body mass index (BMI)-matched healthy controls. MCP-1 was studied in mouse collecting duct cells, human proximal tubular cells, and fetal kidney tissue.

Results

Fifty-three genotyped ADPKD patients and 53 controls were included. The mean (SD) age was 10.4 (5.9) versus 10.5 (6.1) years (P = 0.543), and the estimated glomerular filtration rate (eGFR) was 122.7 (39.8) versus 114.5 (23.1) ml/min per 1.73 m² (P = 0.177) in patients versus controls, respectively. Plasma copeptin and EGF secretion were comparable between groups. The median (interquartile range) urinary MCP-1 (pg/mg creatinine) was significantly higher in ADPKD patients (185.4 [213.8]) compared with controls (154.7 [98.0], P = 0.010). Human proximal tubular cells with a heterozygous PKD1 mutation and mouse collecting duct cells with a PKD1 knockout exhibited increased MCP-1 secretion. Human fetal ADPKD kidneys displayed prominent MCP-1 immunoreactivity and M2 macrophage infiltration.

Conclusion

An increase in tubular MCP-1 secretion is an early event in ADPKD. MCP-1 is an early disease severity marker and a potential treatment target.

Strategies for asymmetrical triacetate dialyser heparin-free effective haemodialysis: the SAFE study

Background

In haemodialysis, maintaining patency of the extracorporeal circuit requires the use of anticoagulants. Although (low molecular weight) heparins are the mainstay, these are not well tolerated in all patients. Alternative approaches include saline infusion, citrate-containing dialysate, regional citrate anticoagulation or the use of heparin-coated membranes. Asymmetric cellulose triacetate (ATA) dialysers have a low degree of platelet contact activation and might be an alternative to heparin-coated dialysers. The aim of this study was to test the clotting propensity of ATA when used without systemic anticoagulation.

Methods

We performed a Phase II pilot study in maintenance dialysis patients. The ‘Strategies for Asymmetrical Triacetate dialyzer heparin-Free Effective hemodialysis’ (SAFE) study was a two-arm open-label crossover study. In Arm A, patients were dialysed using 1.9 m² ATA membranes in combination with a citrate-containing dialysate (1 mM). In Arm B, the ATA membrane was combined with high-volume predilution haemodiafiltration (HDF) without any other anticoagulation. The primary endpoint was the success rate to complete 4 h of haemodialysis without preterm clotting. Secondary endpoints included time to clotting and measures of dialysis adequacy.

Results

We scheduled 240 dialysis sessions (120/arm) in 20 patients. Patients were randomized 1:1 to start with Arm A or B. All patients crossed to the other arm halfway through the study. A total of 232 (96.7%) study treatments were delivered. Overall, 23 clotting events occurred, 7 in Arm A and 16 in Arm B. The success rate in Arm A (ATA + citrate-containing dialysate) was 90.8/94.0% [intention to treat (ITT)/as treated]. The success rate in Arm B (ATA + predilution HDF) was 83.3/86.2% (ITT/as treated). Time to clotting was borderline significantly better in Arm A (Mantel-Cox log rank P = 0.05).

Conclusion

ATA dialysers have a low clotting propensity and both predilution HDF and a citrate-containing dialysate resulted in high rates of completed dialysis sessions.

Measures of Loop Diuretic Efficiency and Prognosis in Chronic Kidney Disease

BACKGROUND

The evolution and prognostic impact of loop diuretic efficiency according to chronic kidney disease (CKD) severity is unclear.

METHODS

This retrospective cohort study includes 783 CKD patients on oral loop diuretic therapy with a 24-h urine collection available. Acute kidney injury and history of renal replacement therapy were exclusion criteria. Patients were stratified according to Kidney Disease Improving Global Outcomes (KDIGO) glomerular filtration rate class. Loop diuretic efficiency was calculated as urine output, natriuresis, and chloruresis, each adjusted for loop diuretic dose, and compared among strata. Risk for onset of dialysis and all-cause mortality was evaluated.

RESULTS

Loop diuretic efficiency metrics decreased from KDIGO class IIIB to IV in furosemide users and from KDIGO class IV to V with all loop diuretics (p value <0.05 for all comparisons). The correlation between loop diuretic efficiency and creatinine clearance was moderate at best (Spearman's ρ 0.298-0.436; p value <0.001 for all correlations). During median follow-up of 45 months, 457 patients died (58%) and 63 received kidney transplantation (8%), while dialysis was started before in 328 (42%). All loop diuretic efficiency metrics were significantly and independently associated with both the risk for dialysis and all-cause mortality. In KDIGO class IV/V patients, low loop diuretic efficiency (i.e., urine output adjusted for loop diuretic dose ≤1,000 mL) shortened median time to dialysis with 24 months and median time to all-cause mortality with 23 months.

CONCLUSION

Low loop diuretic efficiency is independently associated with a shorter time to dialysis initiation and a higher risk for all-cause mortality in CKD.

Natural history of mineral metabolism, bone turnover and bone mineral density in de novo renal transplant recipients treated with a steroid minimization immunosuppressive protocol

The skeletal effects of renal transplantation are not completely understood, especially in patients managed with a steroid minimization immunosuppressive protocol and long term. We enrolled 69 adult transplant recipients (39 males; ages 51.1 ± 12.2 years), free of antiresorptive therapy and managed with a steroid minimization immunosuppressive protocol, into a 5-year prospective observational study to evaluate changes in areal bone mineral density (aBMD), mineral metabolism and bone remodelling. Dual energy X-ray absorptiometry, laboratory parameters of mineral metabolism (including parathyroid hormone, sclerostin and fibroblast growth factor 23) and non-renal cleared bone turnover markers (BTMs) (bone-specific alkaline phosphatase, trimeric N-terminal propeptide and tartrate-resistant acid phosphatase 5b) were assessed at baseline and 1 and 5 years post-transplantation. The mean cumulative methylprednisolone exposure at 1 and 5 years amounted to 2.5 ± 0.8 and 5.8 ± 3.3 g, respectively. Overall, bone remodelling activity decreased after transplantation. Post-transplant aBMD changes were minimal and were significant only in the ultradistal radius during the first post-operative year {median -2.2% [interquartile range (IQR) -5.9-1.2] decline, P = 0.01} and in the lumbar spine between Years 1 and 5 [median 1.6% (IQR -3.2-7.0) increase, P = 0.009]. BTMs, as opposed to mineral metabolism parameters and cumulative corticosteroid exposure, associated with aBMD changes, both in the early and late post-transplant period. Most notably, aBMD changes inversely associated with bone remodelling changes. In summary, in de novo renal transplant recipients treated with a steroid minimization immunosuppressive protocol, BMD changes are limited, highly variable and related to remodelling activity rather than corticosteroid exposure.

P1799GENOTYPE-PHENOTYPE CORRELATION IN A PEDIATRIC ADPKD COHORT

Background and Aims

The correlation between genotype and phenotype is well described in ADPKD adults. PKD2 is milder than PKD1 disease, with end stage kidney disease (ESKD) occurring on average 20 years later, and patients with PKD1 truncating mutations having a more severe outcome than PKD1 non-truncating mutations. Still, large differences in outcome occur even within families carrying the same gene variation. Only a few cases series reported the genetic profile of severely affected ADPKD children and suggest an additional effect of hypomorphic genes. We therefore aim to analyse the geno-phenotype profile in a well characterized pediatric ADPKD cohort.

Method

Clinical, familial, biological and imaging data were collected longitudinally in children diagnosed with ADPKD. Genotypic analysis was done using a custom Agilent SureSelect gene panel containing 136 ciliopathy-associated genes, including PKD1 and PKD2. Mutations and/or variants identified were individually evaluated for pathogenicity.

Results

57 ADPKD children from 44 families were diagnosed at a mean (± SD) age of 4.1 (±4.8) years. ADPKD diagnosis was made in 32 children (56%) because of asymptomatic screening as requested by the family; 7 (12%) due to presenting symptoms (6 due to urinary tract infection and 1 due to post-traumatic macroscopic hematuria); 9 (16%) due to a coincidental finding of renal cysts on US performed for another reason and in 9 cases (16%) a prenatal diagnosis was performed. Twenty-nine children (51%) met the definition of very-early onset (VEO) disease.

We identified pathogenic mutations in 100% of our patients, in which the prevalence of PKD1 truncating, PKD1 non-truncating, PKD2 and GANAB mutations was 75%, 19%, 4%, and 2%, respectively. Four cases (7%) were due to a de novo mutation. Interestingly, in 29 patients (51%) the germline mutation was the only identified mutation. However, in the rest of the subjects additional variants were identified in other ciliopathy-associated genes. In 12 cases (21%) the additional identified variants found in either the PKD, PMM2, HNF1B, DNAJC1, CEP290, NEK1, MKKS, NPHP4 or PKHD1 genes were scored to have a potential phenotypic effect, which will be evaluated by continued follow-up of this cohort.

Conclusion

We report the first large cohort of genotyped ADPKD children, including an extensive panel of ciliopathy genes next to the PKD genes. Interestingly, we found a high prevalence of additional and potentially modifying variants in this young population.

P1064HEPARIN-FREE DIALYSIS: A PHASE II PILOT STUDY USING ASYMMETRIC TRIACETATE (ATA) CELLULOSE DIALYZERS

Background and Aims

Not all dialysis patients tolerate heparin anticoagulation. Heparin should be avoided in patients at high risk of bleeding. Strategies include saline infusion, citrate-containing dialysate, regional citrate anticoagulation and heparin-coated membranes. We recently studied the combination of a heparin-coated membrane and citrate-containing dialysate, with a success rate of 94% . Although this combination resulted in low rates of clotting, heparin-coated membranes are not ubiquitously available. The quest for easy to perform, safe and affordable heparin-free dialysis is on. Asymmetric cellulose triacetate (ATA) dialyzers have a low degree of platelet contact activation and might be an alternative to heparin-coated dialyzers.

Method

We performed a phase II pilot study in maintenance dialysis patients. The ‘Strategies for Asymmetrical Triacetate dialyzer heparin-Free Effective hemodialysis (SAFE study)’ was a two-arm open-label cross-over study. In Arm 1, patients were dialyzed using a 1.9 m2 ATA membrane (Solacea™-19H, Nipro Corp., Japan) in combination with citrate (1 mM) containing dialysate. In Arm 2, patients were dialyzed with the same 1.9 m2 ATA membrane, in combination with high volume predilution hemodiafiltration. The primary endpoint was the success rate to complete 4 hours of hemodialysis without preterm clotting.

Results

We scheduled 240 dialysis sessions (120 per arm) in twenty patients. Ten patients were randomized to start in Arm 1, the others to Arm 2. All patients crossed to the other arm halfway the study. 232 (96.7%) study treatments were delivered. Overall, 23 clotting events occurred, 7 in Arm 1 and 16 in Arm 2. Success rate in Arm 1 (ATA + citrate containing dialysate) was 90.8 / 94.0 % (intention to treat/ as treated). Success rate in Arm 2 (ATA + predilution HDF) was 83.3 / 86.2 % (intention to treat/ as treated). Therapy survival was borderline significantly better in Arm 1(Mantel-Cox log rank P = 0.05).

Conclusion

Asymmetric cellulose triacetate (ATA) dialyzers have a low clotting propensity. In combination with citrate-containing dialysate, asymmetric cellulose triacetate (ATA) may be a suitable alternative to heparin-coated membranes for systemic heparin-free hemodialysis.

Sevelamer Use in End-Stage Kidney Disease (ESKD) Patients Associates with Poor Vitamin K Status and High Levels of Gut-Derived Uremic Toxins: A Drug-Bug Interaction?

Gut microbial metabolism is not only an important source of uremic toxins but may also help to maintain the vitamin K stores of the host. We hypothesized that sevelamer therapy, a commonly used phosphate binder in patients with end-stage kidney disease (ESKD), associates with a disturbed gut microbial metabolism. Important representatives of gut-derived uremic toxins, including indoxyl sulfate (IndS), p-Cresyl sulfate (pCS), trimethylamine N-oxide (TMAO), phenylacetylglutamine (PAG) and non-phosphorylated, uncarboxylated matrix-Gla protein (dp-ucMGP; a marker of vitamin K status), were analyzed in blood samples from 423 patients (65% males, median age 54 years) with ESKD. Demographics and laboratory data were extracted from electronic files. Sevelamer users (n = 172, 41%) were characterized by higher phosphate, IndS, TMAO, PAG and dp-ucMGP levels compared to non-users. Sevelamer was significantly associated with increased IndS, PAG and dp-ucMGP levels, independent of age, sex, calcium-containing phosphate binder, cohort, phosphate, creatinine and dialysis vintage. High dp-ucMGP levels, reflecting vitamin K deficiency, were independently and positively associated with PAG and TMAO levels. Sevelamer therapy associates with an unfavorable gut microbial metabolism pattern. Although the observational design precludes causal inference, present findings implicate a disturbed microbial metabolism and vitamin K deficiency as potential trade-offs of sevelamer therapy.

Implications of early diagnosis of autosomal dominant polycystic kidney disease: A post hoc analysis of the TEMPO 3:4 trial

It is unknown whether early diagnosis of autosomal dominant polycystic kidney disease (ADPKD) can enable earlier management and improve outcomes. We conducted a post hoc analysis of data from the TEMPO 3:4 trial. Subjects were stratified by ADPKD diagnosis at age ≤18 (childhood diagnosis [CD]) or>18 (adulthood diagnosis [AD]). Groups were compared for baseline characteristics and total kidney volume (TKV) growth and estimated glomerular filtration rate (eGFR) decline over 3 years. 294 CD and 1148 AD subjects were analyzed. At inclusion, CD subjects were younger (mean age 34.2 versus 39.8 years; p < 0.0001) and had better eGFR (mean ± SD 87.4 ± 23.9 versus 80.1 ± 20.7 mL/min/1.73 m²; p < 0.0001), while CD had more severe Mayo risk classification (p < 0.0001) and more PKD1 mutations (p = 0.003). No statistical differences were found in TKV or eGFR change. At study end, placebo-treated CD subjects had better eGFR than projected by a prediction equation (mean difference ±SD for observed versus predicted eGFR: 2.18 ± 10.7 mL/min/1.73 m²; p = 0.0475). However, these results are not confirmed when excluding stage 1 CKD. Whether CD subjects, despite their risk profile, have a slower disease course than predicted remains inconclusive. Future studies are needed to confirm that early diagnosis and management can alter the disease course of ADPKD.

Non-invasive Quantification of Fat Deposits in Skeletal Muscle Predicts Cardiovascular Outcome in Kidney Failure

Fat accumulation in skeletal muscle was recently established as a major risk factor for cardiovascular disease (CVD) in the general population, but its relevance for patients with kidney failure is unknown. Here we examined the potential association between muscle radiation attenuation (MRA), a non-invasive indicator of fat deposits in muscle, and cardiovascular events in patients with kidney failure treated with peritoneal dialysis (PD) and investigated dynamic changes and determinants of MRA in this population. We retrospectively assessed MRA on computed tomography images collected yearly in 101 incident patients with kidney failure starting PD between January 2006 and December 2015. After a median of 21 months on dialysis, 34 patients had 58 non-fatal cardiovascular events, and 22 patients had died. Baseline MRA was associated with cardiovascular events during time on dialysis, and patients with higher MRA (reflecting lower amounts of fat in muscle) showed a reduced incidence of CVD, independently of traditional risk factors (adjusted HR, 0.91; 95% CI, 0.86-0.97, P = 0.006). Multivariate regression analysis identified old age, female gender, visceral fat area, and low residual urine volume as independent determinants of MRA. As compared with reference values from a healthy population, patients with kidney failure had lower MRA (i.e., increased fat accumulation), independently of age, gender, and body-mass index. The subset of patients who underwent kidney transplantation showed a significant increase in MRA after restoration of kidney function. These observations expand the association between ectopic fat accumulation and CVD to the population on dialysis, and suggest that kidney failure is reversibly associated with fatty muscle infiltration.

Persistent primary cytomegalovirus infection in a kidney transplant recipient: Multi-drug resistant and compartmentalized infection leading to graft loss

Cytomegalovirus (CMV) is one of the most common opportunistic infections after transplantation. To prevent CMV infections, universal prophylaxis and pre-emptive therapy with ganciclovir or its prodrug valganciclovir is applied. However, prolonged antiviral therapy may result in drug-resistance emergence. We describe a case of a 43-year-old CMV-seronegative patient who underwent kidney transplantation from a CMV-seropositive donor and developed CMV disease despite valganciclovir prophylaxis. CMV viral load increased even though valgangiclovir dose was augmented and immunosuppressive therapy reduced. CMV genotyping revealed mutations in the viral UL97 protein kinase, explaining ganciclovir-resistant CMV infection. The viral load failed to respond to foscavir, cidofovir and CMV-neutralizing immunoglobulins. Kidney allograft dysfunction developed 3 months post-transplantation with a histopathologic diagnosis of CMV nephropathy and potentially concomitant T-cell mediated rejection. A transplantectomy was performed on day 164 post-transplantation since the patient had uncontrollable CMV disease associated with a circulating multidrug-resistant DNA polymerase-mutant virus. Detailed monitoring in this patient demonstrated hallmarks of complicated CMV disease: (i) relatively rapid evolution of drug-resistant CMV mutants in the setting of persistent high blood viral loads, (ii) emergence of viral drug-resistance linked to acute graft rejection, (iii) transient and, thereafter, lack of response to various anti-CMV treatments, (iv) compartmentalization and heterogeneity of CMV viral populations, (v) possible differential ability of viral mutants to cause disease in the graft, and (vi) detection of minor viral variants by next generation sequencing. Translational research platforms that provide rapid molecular genotyping for detection of CMV drug-resistance are essential in guiding CMV disease management in high-risk transplant recipients.

Oxidative stress in chronic kidney disease

Oxidative stress (OS), defined as disturbances in the pro-/antioxidant balance, is harmful to cells due to the excessive generation of highly reactive oxygen (ROS) and nitrogen (RNS) species. When the balance is not disturbed, OS has a role in physiological adaptations and signal transduction. However, an excessive amount of ROS and RNS results in the oxidation of biological molecules such as lipids, proteins, and DNA. Oxidative stress has been reported in kidney disease, due to both antioxidant depletions as well as increased ROS production. The kidney is a highly metabolic organ, rich in oxidation reactions in mitochondria, which makes it vulnerable to damage caused by OS, and several studies have shown that OS can accelerate kidney disease progression. Also, in patients at advanced stages of chronic kidney disease (CKD), increased OS is associated with complications such as hypertension, atherosclerosis, inflammation, and anemia. In this review, we aim to describe OS and its influence on CKD progression and its complications. We also discuss the potential role of various antioxidants and pharmacological agents, which may represent potential therapeutic targets to reduce OS in both pediatric and adult CKD patients.

Oxidative stress in autosomal dominant polycystic kidney disease: player and/or early predictor for disease progression?

Autosomal dominant polycystic kidney disease (ADPKD), caused by mutations in PKD1 or PKD2 genes, is the most common hereditary renal disease. Renal manifestations of ADPKD are gradual cyst development and kidney enlargement ultimately leading to end-stage renal disease. ADPKD also causes extrarenal manifestations, including endothelial dysfunction and hypertension. Both of these complications are linked with reduced nitric oxide levels related to excessive oxidative stress (OS). OS, defined as disturbances in the prooxidant/antioxidant balance, is harmful to cells due to the excessive generation of highly reactive oxygen and nitrogen free radicals. Next to endothelial dysfunction and hypertension, there is cumulative evidence that OS occurs in the early stages of ADPKD. In the current review, we aim to summarize the cardiovascular complications and the relevance of OS in ADPKD and, more specifically, in the early stages of the disease. First, we will briefly introduce the link between ADPKD and the early cardiovascular complications including hypertension. Secondly, we will describe the potential role of OS in the early stages of ADPKD and its possible importance beyond the chronic kidney disease (CKD) effect. Finally, we will discuss some pharmacological agents capable of reducing reactive oxygen species and OS, which might represent potential treatment targets for ADPKD.

Poor Vitamin K Status Is Associated With Low Bone Mineral Density and Increased Fracture Risk in End-Stage Renal Disease

Chronic kidney disease and osteoporosis are major public health problems associated with an aging population. Vitamin K insufficiency is prevalent among patients with end-stage renal disease (ESRD). Preliminary data indicate that poor vitamin K status may compromise bone health and that increased inflammation may be in the causal pathway. We performed an ancillary analysis of data collected in the frame of prospective observational cohort studies exploring various aspects of bone health in de novo renal transplant recipients to investigate the association between vitamin K status, inflammation, bone mineral density, and incident clinical fractures. Parameters of mineral metabolism (including biointact PTH and FGF23, sclerostin, calcidiol, calcitriol) and inflammation (CRP and IL-6), osteoprotegerin, bone turnover markers (P1NP, BsAP, and TRAP5B), and dephosphorylated-uncarboxylated Matrix Gla Protein (dp-ucMGP) were assessed on blood samples collected immediately prior to kidney transplantation in 468 patients. Areal bone mineral density (aBMD) was measured at the lumbar spine and femoral neck by dual-energy X-ray absorptiometry within 14 days posttransplant. Poor vitamin K status, defined by dp-ucMGP >500 nmol/L, was highly prevalent (90%). High dp-ucMGP levels independently associated with elevated inflammatory markers and low aBMD. No associations were observed between vitamin K status and bone turnover markers. During a median follow-up of 5.1 years, 33 patients sustained a fragility fracture. In Cox-proportional hazards analysis, a dp-ucMGP above median associated with incident fractures, independent of classical determinants, including age, gender, history of fracture, and aBMD (HR 2.21; 95% CI, 1.00 to 4.91; p < 0.05). In conclusion, poor vitamin K status associates with inflammation and low aBMD in patients with ESRD and confers an increased risk of incident fractures in de novo renal transplant recipients. © 2018 American Society for Bone and Mineral Research.

Unmet needs and challenges for follow-up and treatment of autosomal dominant polycystic kidney disease: the paediatric perspective

Awareness is growing that the clinical course of autosomal dominant polycystic kidney disease (ADPKD) already begins in childhood, with a broad range of both symptomatic and asymptomatic features. Knowing that parenchymal destruction with cyst formation and growth starts early in life, it seems reasonable to assume that early intervention may yield the best chances for preserving renal outcome. Interventions may involve lifestyle modifications, hypertension control and the use of disease-modifying treatments once these become available for the paediatric population with an acceptable risk and side-effect profile. Until then, screening of at-risk children is controversial and not generally recommended since this might cause psychosocial and financial harm. Also, the clinical and research communities are facing important questions as to the nature of potential interventions and their optimal indications and timing. Indeed, challenges include the identification and validation of indicators, both measuring and predicting disease progression from childhood, and the discrimination of slow from rapid progressors in the paediatric population. This discrimination will improve both the cost-effectiveness and benefit-to-risk ratio of therapies. Furthermore, we will need to define outcome measures, and to evaluate the possibility of a potential therapeutic window of opportunity in childhood. The recently established international register ADPedKD will help in elucidating these questions. In this review, we provide an overview of the current knowledge on paediatric ADPKD as a future therapeutic target population and its unmet challenges.

Renal progression factors in young patients with tuberous sclerosis complex: a retrospective cohort study

BACKGROUND

Renal pathology in tuberous sclerosis complex (TSC) is characterized by the growth of angiomyolipoma and renal cysts, and in rare cases renal cell carcinoma. Other consequences of renal involvement in TSC, including hypertension, proteinuria, and hyperfiltration, are not well studied. We aimed to analyze the early manifestations of the renal TSC phenotype in a young TSC cohort and to explore common, modifiable risk factors.

METHODS

In this retrospective cohort study, TSC patients attending the TSC clinics of two tertiary hospitals were included. Data on demographics, history, genotype, kidney function, hematuria, proteinuria, blood pressure, and renal imaging were collected.

RESULTS

Eighty patients were included, with a median age of 0.8 years (0.0-63.0) at first presentation, and a median follow-up time of 10.2 (0.4-41.0) years. Mutation analysis was available in 64 patients (80%). Renal lesions (cysts or angiomyolipoma) were observed in 55/73 (75%). Thirty-two percent (19/60) were hypertensive, 8/51 (16%) had proteinuria, and 18/71 (25%) had hyperfiltration (median eGFR 154 ml/min/m²). Six (7.5%) patients had developed end stage renal disease at the last follow-up. No association was found between hyperfiltration, hypertension, or proteinuria and CKD ≥ 3. Cox regression showed a significant positive association between the presence of a renal intervention and CKD ≥ 3 (Hazard-Ratio 3.91, P < 0.05).

CONCLUSIONS

Besides renal cysts and angiomyolipoma, the modifiable progression factors hypertension, proteinuria, and hyperfiltration occur frequently and early in TSC patients. This represents a preventive treatment target.

Clinicians' attitude towards family planning and timing of diagnosis in autosomal dominant polycystic kidney disease

Several ethical aspects in the management of Autosomal Dominant Polycystic Kidney Disease (ADPKD) are still controversial, including family planning and testing for disease presence in at-risk individuals. We performed an online survey aiming to assess the opinion and current clinical practice of European pediatric and adult nephrologists, as well as geneticists. A total of 410 clinicians (53% male, mean (SD) age of 48 (10) years) responded, including 216 pediatric nephrologists, 151 adult nephrologists, and 43 clinical geneticists. While the 3 groups agreed to encourage clinical testing in asymptomatic ADPKD minors and adults, only geneticists would recommend genetic testing in asymptomatic at-risk adults (P<0.001). Statistically significant disagreement between disciplines was observed regarding the ethical justification of prenatal genetic diagnosis, termination of pregnancy and pre-implantation genetic diagnosis (PGD) for ADPKD. Particularly, PGD is ethically justified according to geneticists (4.48 (1.63)), whereas pediatric (3.08 (1.78); P<0.001) and adult nephrologists (3.66 (1.88); P<0.05) appeared to be less convinced. Our survey suggests that most clinicians support clinical testing of at-risk minors and adults in ADPKD families. However, there is no agreement for genetic testing in asymptomatic offspring and for family planning, including PGD. The present data highlight the need for a consensus among clinicians, to avoid that ADPKD families are being given conflicting information.

Cladophialophora bantiana osteomyelitis in a renal transplant patient

Cladophialophora bantiana is a neurotropic dematiaceous fungus which rarely causes disseminated disease. We report a case of proven C. bantiana osteomyelitis in a renal transplant recipient, complicated with probable cerebral disease. Stable disease was reached after combined antifungal therapies, immune enhancement and amputation of the infected lower limb.

The influence of renal transplantation on retained microbial-human co-metabolites

BACKGROUND

Colonic microbial metabolism contributes substantially to uraemic retention solutes accumulating in chronic kidney disease (CKD) and various microbial-human co-metabolites relate to adverse outcomes. The influence of renal transplantation on these solutes is largely unexplored.

METHODS

We prospectively followed 51 renal transplant recipients at the time of transplantation, Day 7 and Months 3 and 12 post-transplantation. Serum levels of p-cresyl sulphate (PCS), p-cresyl glucuronide (PCG), indoxyl sulphate (IS), trimethylamine N-oxide (TMAO) and phenylacetylglutamine (PAG) were determined with liquid chromatography-tandem mass spectrometry. At each time point, transplant recipients were compared with CKD control patients matched for age, gender, diabetes mellitus and renal function. Determinants of serum levels were also compared between an unrelated cohort of 65 transplant recipients at Month 3 post-transplantation and CKD patients with 24-h urinary collection.

RESULTS

Serum levels of the tested microbial-human co-metabolites significantly decreased following renal transplantation (P < 0.001). At each time point post-transplantation, serum levels of PCS, PCG, PAG and, to a lesser extent, IS, but not TMAO, were significantly lower in transplant recipients when compared with CKD control patients. Further analysis demonstrated significantly lower 24-h urinary excretion of these solutes in transplant recipients (P < 0.001). Also, renal clearances of PCG, IS, TMAO and PAG were significantly lower in transplant recipients without differences in estimated glomerular filtration rate.

CONCLUSIONS

Colonic microbiota-derived uraemic retention solutes substantially decrease following renal transplantation. The 24-h urinary excretion of these microbial-human co-metabolites is lower when compared with CKD patients, suggesting an independent influence of transplantation on intestinal uptake, a composite of colonic microbial metabolism and intestinal absorption. Renal solute handling may differ between transplant recipients and CKD patients.

Phosphorus metabolism in peritoneal dialysis- and haemodialysis-treated patients

BACKGROUND

Phosphorus control is generally considered to be better in peritoneal dialysis (PD) patients as compared with haemodialysis (HD) patients. Predialysis phosphorus concentrations are misleading as a measure of phosphorus exposure in HD, as these neglect significant dialysis-related fluctuations.

METHODS

Parameters of mineral metabolism, including parathyroid hormone (PTH) and fibroblast growth factor-23 (FGF-23), were determined in 79 HD and 61 PD patients. In PD, phosphorus levels were determined mid-morning. In HD, time-averaged phosphorus concentrations were modelled from measurements before and after the mid-week dialysis session. Weekly renal, dialytic and total phosphorus clearances as well as total mass removal were calculated from urine and dialysate collections.

RESULTS

Time-averaged serum phosphorus concentrations in HD (3.5 ± 1.0 mg/dL) were significantly lower than the mid-morning concentrations in PD (5.0 ± 1.4 mg/dL, P < 0.0001). In contrast, predialysis phosphorus concentrations (4.6 ± 1.4 mg/dL) were not different from PD. PTH and FGF-23 levels were significantly higher in PD. Despite higher residual renal function, total phosphorus clearance was significantly lower in PD (P < 0.0001). Total phosphorus mass removal, conversely, was significantly higher in PD (P < 0.05).

CONCLUSIONS

Our data suggest that the time-averaged phosphorus concentrations in patients treated with PD are higher as compared with patients treated with HD. Despite a better preserved renal function, total phosphorus clearance is lower in patients treated with PD. Additional studies are needed to confirm these findings in a population with a different demographic profile and dietary background and to define clinical implications.

Sclerostin Serum Levels and Vascular Calcification Progression in Prevalent Renal Transplant Recipients

CONTEXT

Vascular calcification (VC) is prevalent and progressive in renal transplant recipients (RTRs). Recent cross-sectional data suggest that activated Wnt signaling contributes to VC.

OBJECTIVE

The objective was to investigate whether circulating levels of the Wnt antagonist sclerostin associate with progression of VC.

DESIGN

This was a post hoc analysis of the longitudinal observational Brussels Renal Transplant Cohort study.

SETTING

The setting was a tertiary care academic hospital.

PATIENTS

Coronary artery calcification and aorta calcification were measured by multislice spiral computerized tomography in 268 prevalent RTRs (age, 53 ± 13 y; 61% male) at baseline and remeasured in 189 patients after a median follow-up of 4.4 years. Baseline serum sclerostin levels were assessed on stored blood samples. Regression analysis was performed to identify determinants of baseline VC and progression.

MAIN OUTCOME MEASURE

The main outcome measure was progression of VC.

RESULTS

VC was present in up to 84% of participants at baseline. Almost half of the patients showed progression of VC, according to Hokanson criteria. The cross-sectional analysis at baseline demonstrated a direct association between sclerostin levels and VC score in univariate analysis, which became inverse after adjustment for age, gender and PTH level. Remarkably, a lower sclerostin level was identified as an independent determinant of a higher baseline aorta calcification score in the final regression model. Moreover, baseline sclerostin levels showed an inverse association with VC progression, at least after adjustment for traditional risk factors.

CONCLUSIONS

Serum sclerostin levels inversely associated with VC burden and progression in prevalent RTRs after adjustment for traditional risk factors. Our data corroborate previous findings in nontransplanted chronic kidney disease patients and support the notion that sclerostin may be up-regulated in the vascular wall during the VC process as part of a local counterregulatory mechanism directed to suppress VC. Additional clinical and experimental data are required for confirmation.

Lanreotide Reduces Liver Volume, But Might Not Improve Muscle Wasting or Weight Loss, in Patients With Symptomatic Polycystic Liver Disease

BACKGROUND & AIMS

Polycystic liver disease (PCLD) can induce malnutrition owing to extensive hepatomegaly and patients might require liver transplantation. Six months of treatment with the somatostatin analogue lanreotide (120 mg) reduces liver volume. We investigated the efficacy of a lower dose of lanreotide and its effects on nutritional status.

METHODS

We performed an 18-month prospective study at 2 tertiary medical centers in Belgium from January 2011 through August 2012. Fifty-nine patients with symptomatic PCLD were given lanreotide (90 mg, every 4 weeks) for 6 months. Patients with reductions in liver volume of more than 100 mL (responders, primary end point) continued to receive lanreotide (90 mg) for an additional year (18 months total). Nonresponders were offered increased doses, up to 120 mg lanreotide, until 18 months. Liver volume and body composition were measured by computed tomography at baseline and at months 6 and 18. Patients also were assessed by the PCLD-specific complaint assessment at these time points.

RESULTS

Fifty-three patients completed the study; 21 patients (40%) were responders. Nineteen of the responders (90%) continued as responders until 18 months. At this time point, they had a mean reduction in absolute liver volume of 430 ± 92 mL. In nonresponders (n = 32), liver volume increased by a mean volume of 120 ± 42 mL at 6 months. However, no further increase was observed after dose escalation in the 24 patients who continued to the 18-month end point. All subjects had decreased scores on all subscales of the PCLD-specific complaint assessment, including better food intake (P = .04). Subjects did not have a mean change in subcutaneous or visceral fat mass, but did have decreases in mean body weight (2 kg) and total muscle mass (1.06 cm(2)/h(2)). Subjects also had a significant mean reduction in their level of insulin-like growth factor 1, from 19% below the age-adjusted normal range level at baseline to 50% at 18 months (P = .002).

CONCLUSIONS

In a prospective study, we observed that low doses of lanreotide (90 mg every 4 weeks) reduced liver volumes and symptoms in patients with PCLD. However, patients continued to lose weight and muscle mass. The effects of somatostatin analogues on sarcopenia require investigation. Clinicaltrials.gov: NCT01315795.

The effect of anastomosis time on outcome in recipients of kidneys donated after brain death: a cohort study

Whether warm ischemia during the time to complete the vascular anastomoses determines renal allograft function has not been investigated systematically. We investigated the effect of anastomosis time on allograft outcome in 669 first, single kidney transplantations from brain-dead donors. Anastomosis time independently increased the risk of delayed graft function (odds ratio per minute [OR] 1.05, 95% confidence interval [CI] 1.02-1.07, p < 0.001) and independently impaired allograft function after transplantation (p = 0.009, mixed-models repeated-measures analysis). In a subgroup of transplant recipients, protocol-specified biopsies at 3 months (n = 186), 1 year (n = 189), and 2 years (n = 153) were blindly reviewed. Prolonged anastomosis time independently increased the risk of interstitial fibrosis and tubular atrophy on these protocol-specified biopsies posttransplant (p < 0.001, generalized linear models). In conclusion, prolonged anastomosis time is not only detrimental for renal allograft outcome immediately after transplantation, also longer-term allograft function and histology are affected by the duration of this warm ischemia.

Proteinuria as a Noninvasive Marker for Renal Allograft Histology and Failure: An Observational Cohort Study

Proteinuria is routinely measured to assess renal allograft status, but the diagnostic and prognostic values of this measurement for renal transplant pathology and outcome remain unclear. We included 1518 renal allograft recipients in this prospective, observational cohort study. All renal allograft biopsy samples with concomitant data on 24-hour proteinuria were included in the analyses (n=2274). Patients were followed for ≥7 years post-transplantation. Compared with proteinuria <0.3 g/24 h, the hazard ratios for graft failure were 1.14 (95% confidence interval [95% CI], 0.81 to 1.60; P=0.50), for proteinuria 0.3-1.0 g/24 h, 2.17 (95% CI, 1.49 to 3.18; P<0.001), for proteinuria 1.0-3.0 g/24 h, and 3.01 (95% CI, 1.75 to 5.18; P<0.001), for proteinuria >3.0 g/24 h, independent of GFR and allograft histology. The predictive performance of proteinuria for graft failure was lower at 3 months after transplant (area under the receiver-operating characteristic curve [AUC] 0.64, P<0.001) than at 1, 2, and 5 years after transplant (AUC 0.73, 0.71, and 0.77, respectively, all P<0.001). Independent determinants of proteinuria were repeat transplantation, mean arterial pressure, transplant glomerulopathy, microcirculation inflammation, and de novo/recurrent glomerular disease. The discriminatory power of proteinuria for these intragraft injury processes was better in biopsy samples obtained >3 months after transplant (AUC 0.73, P<0.001) than in those obtained earlier (AUC 0.56, P<0.01), with 85% specificity but lower sensitivity (47.8%) for proteinuria >1.0 g/24 h. These data support current clinical guidelines to routinely measure proteinuria after transplant, but illustrate the need for more sensitive biomarkers of allograft injury and prognosis.

Association of HO-1 (GT)n Promoter Polymorphism and Cardiovascular Disease: A Reanalysis of the Literature

BACKGROUND

Heme-oxygenase 1 (HO-1), an inducible heme-degrading enzyme, has antiatherogenic effects through its enzymatic end products. HO-1 gene expression is modulated by a guanidine thymidine dinucleotide ([GT]n) repeat polymorphism in the promoter region. Shorter repeats with (GT)n < 25 are associated with higher inducibility and activity of HO-1.

METHODS

We performed a systematic review of all literature from 1997 to 2013 on the association of the HO-1 (GT)n and cardiovascular disease (CVD). On the basis of predefined criteria (patient characteristics, genotype data format, allelic distribution, repeat length cutoff) 41 articles were selected. Patients were redistributed into 4 homogeneous subpopulations: patients with CVD (CVD group), patients without CVD (nonCVD), 'controls' with unknown cardiovascular status (unspecified) and children younger than 20 years of age (unselected). Genotype distributions (homozygous short [SS] or long [LL], and heterozygous) of the 4 patient categories were compared and odds ratios (ORs) for CVD were calculated using logistic regression analysis.

RESULTS

Overall, the proportion of the SS genotype was lower in CVD compared with nonCVD and unspecified. The ORs for CVD was highest in patients carrying the LL genotype (OR LL vs SS, 1.769 [95% confidence interval, 1.594-1.963]). Furthermore, genotype distribution differed between Caucasian and Asian individuals, the latter having a much higher proportion of the SS genotype (22% vs 11%).

CONCLUSIONS

This review of the available literature on the epidemiological association between the HO-1 (GT)n repeat polymorphism and CVD supports the presumed protective effects of HO-1. The second but probably even more relevant finding of our review is that racial disparities in HO-1 (GT)n repeat length distribution exist and might influence the associations of the genotype with CVD status.