[Significance of phosphate in internal medicine]

Phosphate is essential for bone metabolism and for energy provision. Phosphate homeostasis is achieved by hormonal feedback mechanisms, predominantly parathyroid hormone, fibroblast growth factor 23 and calcitriol, with renal phosphate absorption taking on a special role. Although even large deviations from the serum normal range are rarely symptomatic, the health consequences can be significant. Essentially, the clinically relevant disturbances in phosphate balance can be attributed to three mechanisms: 1. shifts of phosphate between the extracellular space and the cytosol; 2. inadequate phosphate reabsorption in the kidney; 3. decreased intestinal phosphate absorption. Knowledge of physiology enables diagnosis and therapy of phosphate disorders.

Extracorporeal membrane oxygenation during pregnancy and peripartal. An international retrospective multicenter study

INTRODUCTION

Extracorporeal Membrane Oxygenation (ECMO) may be used in the setting of pregnancy or the peripartal period, however its utility has not been well-characterized. This study aims to give an overview on the prevalence of peripartel ECMO cases and further assess the indications and outcomes of ECMO in this setting across multiple centers and countries.

METHODS

A retrospective, multicenter, international cohort study of pregnant and peripartum ECMO cases was performed. Data were collected from six ECMO centers across three continents over a 10-year period.

RESULTS

A total of 60 pregnany/peripartal ECMO cases have been identified. Most frequent indications are acute respiratory distress syndrome (n = 30) and pulmonary embolism (n = 5). Veno-venous ECMO mode was applied more often (77%). ECMO treatment during pregnancy was performed in 17 cases. Maternal and fetal survival was high with 87% (n = 52), respectively 73% (n = 44).

CONCLUSIONS

Various emergency scenarios during pregnancy and at time of delivery may require ECMO treatment. Peripartal mortality in a well-resourced setting is rare, however emergencies in the labor room occur and knowledge of available rescue therapy is essential to improve outcome. Obstetricians and obstetric anesthesiologists should be aware of the availability of ECMO resource at their hospital or region to ensure immediate contact when needed.

EFSUMB 2020 Proposal for a Contrast-Enhanced Ultrasound-Adapted Bosniak Cyst Categorization - Position Statement

The well-established Bosniak renal cyst classification is based on contrast-enhanced computed tomography determining the malignant potential of cystic renal lesions. Ultrasound has not been incorporated into this pathway. However, the development of ultrasound contrast agents coupled with the superior resolution of ultrasound makes it possible to redefine the imaging of cystic renal lesions. In this position statement, an EFSUMB Expert Task Force reviews, analyzes, and describes the accumulated knowledge and limitations and presents the current position on the use of ultrasound contrast agents in the evaluation of cystic renal lesions.

Autosomal dominant polycystic kidney disease: Disrupted pathways and potential therapeutic interventions

Autosomal dominant polycystic kidney disease (ADPKD) is a monogenic inherited renal cystic disease that occurs in different races worldwide. It is characterized by the development of a multitude of renal cysts, which leads to massive enlargement of the kidney and often to renal failure in adulthood. ADPKD is caused by a mutation in PKD1 or PKD2 genes encoding the proteins polycystin-1 and polycystin-2, respectively. Recent studies showed that cyst formation and growth result from deregulation of multiple cellular pathways like proliferation, apoptosis, metabolic processes, cell polarity, and immune defense. In ADPKD, intracellular cyclic adenosine monophosphate (cAMP) promotes cyst enlargement by stimulating cell proliferation and transepithelial fluid secretion. Several interventions affecting many of these defective signaling pathways have been effective in animal models and some are currently being tested in clinical trials. Moreover, the stem cell therapy can improve nephropathies and according to studies were done in this field, can be considered as a hopeful therapeutic approach in future for PKD. This study provides an in-depth review of the relevant molecular pathways associated with the pathogenesis of ADPKD and their implications in development of potential therapeutic strategies.

European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) Policy Document Development Strategy - Clinical Practice Guidelines, Position Statements and Technological Reviews

This document summarizes principles and methodology to guide the creation of Clinical Practice Guidelines, Position Statements und Technological Reviews of the European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB). The purpose of EFSUMB Clinical Practice Guidelines is to provide physicians and sonographers performing or requesting diagnostic and interventional ultrasound examinations with evidence-based recommendations. Position Statements summarize EFSUMB opinions on important current issues in clinical applications, education and training of ultrasound techniques or health care policy related to ultrasound-based imaging and ultrasound-guided interventions. The third type of EFSUMB policy document is the Technological Review, which describes ultrasound techniques and technologies for physicians, medical technicians, engineers and physicists developing ultrasound technology. The whole process of development of EFSUMB policy documents is explained beginning with the decision regarding topics, selection of authors, funding, and planning of the developmental process. Further steps described in this document are the review of the evidence, creation of recommendations, statements and comments, grading of level of evidence and strength of recommendations, and consensus process. Finally, rules for the creation, review, approval, publication and update of EFSUMB policy documents are described.

[Point-of-Care Ultrasound: Teaching and Learning in Ifakara, Tanzania]

Point-of-Care Ultrasound: Teaching and Learning in Ifakara, Tanzania Abstract. Presentation of two practical cases from the point-of-care ultrasound class in Ifakara, Tanzania. The first case shows the sonographic findings of tuberculosis with findings in the lungs, heart, abdominal lymph nodes and spleen. In the second case, detection of an enterobiliary fistula by sonographic live imaging of air passing from the intestine into the gall bladder and causing non-iatrogenic pneumobilia.

Two in One: Epithelioid angiomyolipoma within a classic kidney angiomyolipoma - a case report

Background

Epithelioid angiomyolipoma is defined as potentially malignant mesenchymal neoplasm, characterized by proliferating epithelioid cells, whereas classic angiomyolipoma, composed of fat, smooth muscle cells and dysmorphic vessels, is defined as a potentially benign. The usual or classic angiomyolipoma is often found incidentally on imaging studies, relatively easily identified due to the presence of fat, in contrast to the epithelioid angiomyolipoma that can pose diagnostic challenges.

Case presentation

We report a 51-year-old female patient in which an ultrasonography examination showed a solid mass close to the right renal pelvis with hypoechoic and hyperechoic areas. A differential diagnosis of atypical sinus lipomatosis, lipoma and a transitional cell carcinoma was postulated whereas in a subsequent computed tomography a classic angiomyolipoma was postulated. A re-examination by contrast enhanced ultrasound revealed a striking perfusion difference of the hypoechoic and hyperechoic areas. The hypoechoic area showed homogenous and prolonged enhancement whereas the hypoechoic area displayed a marked slower contrast material flooding and a relatively rapid wash out. The histological analysis from the biopsy of the hyperechoic area showed a classic angiomyolipoma, whereas the sample of the hypoechoic central portion revealed an epithelioid angiomyolipoma. A nephrectomy was performed because of the malignant potential of the epithelioid variant of the angiomyolipoma.

Conclusions

A solid kidney mass with two sharply defined parts, one-part compatible with a classical angiomyolipoma and the other being suspected of carcinoma, is rare, but also illustrative and instructive. The combination of different imaging modalities in the work up of a solid renal mass facilitated to discriminate benign from malignant areas.

Dual mTOR/PI3K inhibition limits PI3K-dependent pathways activated upon mTOR inhibition in autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the development of kidney cysts leading to kidney failure in adulthood. Inhibition of mammalian target of rapamycin (mTOR) slows polycystic kidney disease (PKD) progression in animal models, but randomized controlled trials failed to prove efficacy of mTOR inhibitor treatment. Here, we demonstrate that treatment with mTOR inhibitors result in the removal of negative feedback loops and up-regulates pro-proliferative phosphatidylinositol 3-kinase (PI3K)-Akt and PI3K-extracellular signal-regulated kinase (ERK) signaling in rat and mouse PKD models. Dual mTOR/PI3K inhibition with NVP-BEZ235 abrogated these pro-proliferative signals and normalized kidney morphology and function by blocking proliferation and fibrosis. Our findings suggest that multi-target PI3K/mTOR inhibition may represent a potential treatment for ADPKD.

A Clinical Patient Reporting Tool: Giving ADPKD Patients Back Their Data

Klinischer Patientenbericht: ADPKD-Patienten erhalten Zugriff auf ihre Daten

Zusammenfassung. Studien zur Patientenbeteiligung in der medizinischen Versorgung deuten darauf hin, dass eine intensive Patientenbeteiligung die Gesundheit verbessert und die Vorsorgungszufriedenheit erhöht. Insbesondere bei Behandlungsentscheidungen, die sowohl Schaden als auch Nutzen verursachen, sind gemeinsame Entscheidungen von Patienten und Ärzten entscheidend um den Patienten auf den Behandlungsplan vorbereitet und ihn dafür zu motivieren. Allerdings sind Instrumente, die den Patienten in den klinischen Versorgungsprozess und gemeinsamen Entscheidungsfindung einbeziehen, nicht weit verbreitet. Wir entwickelten ein klinisches Patientendokument für Patienten mit autosomal-dominanter polyzystischer Nierenerkrankung (ADPKD), für die kürzlich eine neue Therapie – Tolvaptan, das die Progression verlangsamt, aber bemerkenswerte Nebenwirkungen hat – zur Verfügung steht. Untersuchungen vor und nach der Entwicklung zeigten, dass ADPKD-Patienten eine Anzeige individueller Schweregradindikatoren mit Benchmarks für vergleichbare Patienten wünschen. Die Kommunikation wird erleichtert und das Vertrauen der Patienten in die gemeinsam gefällten Behandlungsentscheidungen verbessert. Ein solcher Patientenbericht ist leicht auf andere Krankheitsbilder übertragbar und könnte als ein Aspekt eines Patienteninterventionsmodells in klinischen Zentren dienen.

Temporal and geographical external validation study and extension of the Mayo Clinic prediction model to predict eGFR in the younger population of Swiss ADPKD patients

Background

Prediction models in autosomal dominant polycystic kidney disease (ADPKD) are useful in clinical settings to identify patients with greater risk of a rapid disease progression in whom a treatment may have more benefits than harms. Mayo Clinic investigators developed a risk prediction tool for ADPKD patients using a single kidney value. Our aim was to perform an independent geographical and temporal external validation as well as evaluate the potential for improving the predictive performance by including additional information on total kidney volume.

Methods

We used data from the on-going Swiss ADPKD study from 2006 to 2016. The main analysis included a sample size of 214 patients with Typical ADPKD (Class 1). We evaluated the Mayo Clinic model performance calibration and discrimination in our external sample and assessed whether predictive performance could be improved through the addition of subsequent kidney volume measurements beyond the baseline assessment.

Results

The calibration of both versions of the Mayo Clinic prediction model using continuous Height adjusted total kidney volume (HtTKV) and using risk subclasses was good, with R² of 78% and 70%, respectively. Accuracy was also good with 91.5% and 88.7% of the predicted within 30% of the observed, respectively. Additional information regarding kidney volume did not substantially improve the model performance.

Conclusion

The Mayo Clinic prediction models are generalizable to other clinical settings and provide an accurate tool based on available predictors to identify patients at high risk for rapid disease progression.

Kidney volume measurement methods for clinical studies on autosomal dominant polycystic kidney disease

Background

In autosomal dominant polycystic kidney disease (ADPKD), total kidney volume (TKV) is regarded as an important biomarker of disease progression and different methods are available to assess kidney volume. The purpose of this study was to identify the most efficient kidney volume computation method to be used in clinical studies evaluating the effectiveness of treatments on ADPKD progression.

Methods and findings

We measured single kidney volume (SKV) on two series of MR and CT images from clinical studies on ADPKD (experimental dataset) by two independent operators (expert and beginner), twice, using all of the available methods: polyline manual tracing (reference method), free-hand manual tracing, semi-automatic tracing, Stereology, Mid-slice and Ellipsoid method. Additionally, the expert operator also measured the kidney length. We compared different methods for reproducibility, accuracy, precision, and time required. In addition, we performed a validation study to evaluate the sensitivity of these methods to detect the between-treatment group difference in TKV change over one year, using MR images from a previous clinical study. Reproducibility was higher on CT than MR for all methods, being highest for manual and semiautomatic contouring methods (planimetry). On MR, planimetry showed highest accuracy and precision, while on CT accuracy and precision of both planimetry and Stereology methods were comparable. Mid-slice and Ellipsoid method, as well as kidney length were fast but provided only a rough estimate of kidney volume. The results of the validation study indicated that planimetry and Stereology allow using an importantly lower number of patients to detect changes in kidney volume induced by drug treatment as compared to other methods.

Conclusions

Planimetry should be preferred over fast and simplified methods for accurately monitoring ADPKD progression and assessing drug treatment effects. Expert operators, especially on MR images, are required for performing reliable estimation of kidney volume. The use of efficient TKV quantification methods considerably reduces the number of patients to enrol in clinical investigations, making them more feasible and significant.

25-Hydroxyvitamin-D3 serum modulation after use of sunbeds compliant with European Union standards: A randomized open observational controlled trial

BACKGROUND

Regular use of sunbed exposure has been reported to increase 25-hydroxyvitamin-D3 [25(OH)D] serum levels. However, the influence of sunbeds compliant with the recent European Union standard EN-60335-2-27 on 25(OH)D serum levels is unknown.

OBJECTIVE

We investigated the impact of standard sunbed use compliant with the European Union standard on 25(OH)D serum modulation and well-being.

METHODS

In a randomized controlled study, 25(OH)D serum levels were measured at enrollment, after 1 week, and after completion of the 12-week period of sunbed use with twice weekly exposure and compared with the control group without any sunbed exposure.

RESULTS

In the sunbed intervention group (N = 31), a 27% increase of mean 25(OH)D levels was noted 1 week after starting sunbed use (P < .01). However, after 12 weeks, mean 25(OH)D levels had declined and were no longer different from baseline (P = .06). After 12 weeks, 25(OH)D levels did not differ between the intervention and control group (P = .36). Also the 5-item World Health Organization Well-Being Index score did not differ between the sunbed and control groups (P = .19).

LIMITATIONS

For ethical reasons recruitment was limited to persons actively seeking sunbed exposure.

CONCLUSIONS

Standard use of sunbeds compliant with the European Union standard induced a transient increase of 25(OH)D levels, whereas no change in well-being was observed.

Long-term effect of coffee consumption on autosomal dominant polycystic kidneys disease progression: results from the Suisse ADPKD, a Prospective Longitudinal Cohort Study

Background

Previous in vitro experiments of human polycystic kidney disease (PKD) cells reported that caffeine is a risk factor for the promotion of cyst enlargement in patients with autosomal dominant PKD (ADPKD). The relentless progression of ADPKD inclines the majority of physicians to advocate minimization of caffeine consumption despite the absence of clinical data supporting such a recommendation so far. This is the first clinical study to assess prospectively the association between coffee consumption and disease progression in a longitudinal ADPKD cohort.

Methods

Information on coffee consumption and disease progression was collected at each follow-up visit using standardized measurement methods. The main model for the outcomes, kidney size (height-adjusted total kidney volume, htTKV) and kidney function (estimated glomerular filtration rate, eGFR), was a linear mixed model. Patients entered the on-going Swiss ADPKD study between 2006 and June 2014 and had at least 1 visit every year. The sample size of the study population was 151 with a median follow-up of 4 visits per patient and a median follow-up time of 4.38 years.

Results

After multivariate adjustment for age, smoking, hypertension, sex, body mass index and an interaction term (coffee*visit), coffee drinkers did not have a statistically significantly different kidney size compared to non-coffee drinkers (difference of −33.03 cm³ height adjusted TKV, 95% confidence interval (CI) from −72.41 to 6.34, p = 0.10). After the same adjustment, there was no statistically significant difference in eGFR between coffee and non-coffee drinkers (2.03 ml/min/1.73 m², 95% CI from −0.31 to 4.31, p = 0.089).

Conclusion

Data derived from our prospective longitudinal study do not confirm that drinking coffee is a risk factor for ADPKD progression.

Electronic supplementary material

The online version of this article (doi:10.1007/s40620-017-0396-8) contains supplementary material, which is available to authorized users.

Allogeneic islet cells implant on poly-l-lactide matrix to reduce hyperglycaemia in streptozotocin-induced diabetic rat

OBJECTIVE

To demonstrate the effects of allogeneic islet cell matrix implants for glycaemic control in rats with induced diabetes.

METHOD

Sprague-Dawley rats were used as allogeneic donors of islet cells. Cells were seeded on three-dimensional proprietary poly-(l-lactide) matrices. Animals were rendered diabetic and a week later a matrix seeded with islet cells (IMI group) or a control matrix (placebo group) was implanted in the small bowel mesentery. Blood glucose levels were measured weekly for 12 weeks. After sacrifice, implant sections were Gomori stained for beta-cells and immuno-stained for insulin 3, 4, 5, and 6 months post implantation.

RESULTS

82% of seeded islet cells attached to the matrices. In the IMI group blood glucose levels were significantly reduced after implantation compared with before implantation across several time points. In the IMI group beta-cells and insulin-positive cells were identified at the implant site.

CONCLUSION

The islet cell matrix implant reduced the blood glucose levels although complete normo-glycaemia was not established. The islet cell matrix implant may serve as an additional option for islet cell transplantation using 3D scaffold platforms for better survival and function of the islet cells.

EFSUMB Statement on Medical Student Education in Ultrasound [long version]

The European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) recommends that ultrasound should be used systematically as an easy accessible and instructive educational tool in the curriculum of modern medical schools. Medical students should acquire theoretical knowledge of the modality and hands-on training should be implemented and adhere to evidence-based principles. In this paper we report EFSUMB policy statements on medical student education in ultrasound that in a short version is already published in Ultraschall in der Medizin 1.

EFSUMB statement on medical student education in ultrasound [short version]

The European Federation of Societies for Ultrasound in Medicine and Biology (EFSUMB) recommends that ultrasound should be used systematically as an easy accessible and instructive educational tool in the curriculum of modern medical schools. Medical students should acquire theoretical knowledge of the modality and hands-on training should be implemented and adhere to evidence-based principles. In this paper we summarise EFSUMB policy statements on medical student education in ultrasound.

Growth of arachnoid cysts in patients with autosomal dominant polycystic kidney disease: serial imaging and clinical relevance

Background

Autosomal dominant polycystic kidney disease (ADPKD) is an inherited disorder that results in the growth of cysts in the kidneys and other organs. Multisystemic involvement is common including affection of the central nervous system with cerebral aneurysms and arachnoid cysts.

Methods

This is a prospective cohort study to investigate the prevalence and growth rate of arachnoid cysts in ADPKD patients. Participants enrolled in the SUISSE ADPKD cohort were offered cranial imaging for the detection of intracranial alterations. In the case of identified arachnoid cysts, patients were suggested to undergo follow-up imaging to assess the growth rate of the cysts. Volume of arachnoid cysts at the baseline and at follow-up visits was assessed by manual segmentation on a dedicated workstation.

Results

A total of 109 ADPKD patients agreed to undergo cranial imaging. In 14 (12.8%) patients (9 males and 5 females), 18 singular arachnoid cysts were identified. The baseline volumes of individual cysts ranged from 1.8 to 337.6 cm³. During a mean follow-up period of 24 months, the volume changes of 12 individual arachnoid cysts of nine patients ranged from −3.1 to 3.7 cm³. Cystic lesions were mostly localized in the middle fossa. All affected patients were clinically asymptomatic.

Conclusions

We found a higher prevalence of arachnoid cysts in ADPKD patients with more advanced disease. There was a large variability in size and growth. These arachnoid cysts were clinically silent and their growth pattern was subtle and unpredictable, in contrast to the much more foreseeable growth of the renal cysts.

Urinary biomarkers at early ADPKD disease stage

Background

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by a decline in renal function at late disease stage when the majority of functional renal parenchyma is replaced by cystic tissue. Thus, kidney function, assessed by estimated glomerular filtration rate (eGFR) does not well represent disease burden in early disease. Here, we investigated various urinary markers for tubular injury and their association with disease burden in ADPKD patients at early disease course.

Methods

ADPKD patients between 18 and 40 years with an eGFR greater or equal to 70 ml per min per 1.73m² were eligible for this cross-sectional study. Urinary Neutrophil Gelatinase-Associated Lipocalin (NGAL), Kidney Injury Molecule-1 (KIM-1), and Uromodulin (UMOD) were investigated by Enzyme-Linked Immunosorbent Assay. Clara Cell Protein 16 (CC16) was investigated by Latex Immuno Assay. Cryoscopy was performed to assess urine osmolality and Urinary Albumin-to-Creatinine Ratio (UACR) was calculated. The association and the predictive properties of the markers on eGFR and height adjusted total kidney volume (htTKV) was evaluated using multiple regression analysis, incorporating different control variables for adjustment. Internal bootstrapping validated the obtained results.

Results

In 139 ADPKD patients (age 31 ±7 years, mean eGFR of 93 ± 19 ml per min per 1.73 m²) the total kidney volume was negatively correlated with eGFR and UMOD and positive associated with age, UACR, KIM-1 and urine osmolality after adjustment for possible confounders. Urine osmolality and htTKV were also associated with eGFR, whereas no association of CC16, NGAL and UMOD with eGFR or htTKV was found.

Conclusion

UACR and urinary KIM-1 are independently associated with kidney size but not with renal function in our study population. Urine osmolality was associated with eGFR and kidney volume following adjustment for multiple confounders. Despite statistical significance, the clinical value of our results is not yet conceivable. Further studies are needed to evaluate the property of the aforementioned biomarkers to assess disease state at early ADPKD stage.

Diagnosis and Prediction of CKD Progression by Assessment of Urinary Peptides

Progressive CKD is generally detected at a late stage by a sustained decline in eGFR and/or the presence of significant albuminuria. With the aim of early and improved risk stratification of patients with CKD, we studied urinary peptides in a large cross-sectional multicenter cohort of 1990 individuals, including 522 with follow-up data, using proteome analysis. We validated that a previously established multipeptide urinary biomarker classifier performed significantly better in detecting and predicting progression of CKD than the current clinical standard, urinary albumin. The classifier was also more sensitive for identifying patients with rapidly progressing CKD. Compared with the combination of baseline eGFR and albuminuria (area under the curve [AUC]=0.758), the addition of the multipeptide biomarker classifier significantly improved CKD risk prediction (AUC=0.831) as assessed by the net reclassification index (0.303±-0.065; P<0.001) and integrated discrimination improvement (0.058±0.014; P<0.001). Correlation of individual urinary peptides with CKD stage and progression showed that the peptides that associated with CKD, irrespective of CKD stage or CKD progression, were either fragments of the major circulating proteins, suggesting failure of the glomerular filtration barrier sieving properties, or different collagen fragments, suggesting accumulation of intrarenal extracellular matrix. Furthermore, protein fragments associated with progression of CKD originated mostly from proteins related to inflammation and tissue repair. Results of this study suggest that urinary proteome analysis might significantly improve the current state of the art of CKD detection and outcome prediction and that identification of the urinary peptides allows insight into various ongoing pathophysiologic processes in CKD.

Impaired expression of key molecules of ammoniagenesis underlies renal acidosis in a rat model of chronic kidney disease

BACKGROUND

Advanced chronic kidney disease (CKD) is associated with the development of renal metabolic acidosis. Metabolic acidosis per se may represent a trigger for progression of CKD. Renal acidosis of CKD is characterized by low urinary ammonium excretion with preserved urinary acidification indicating a defect in renal ammoniagenesis, ammonia excretion or both. The underlying molecular mechanisms, however, have not been addressed to date.

METHODS

We examined the Han:SPRD rat model and used a combination of metabolic studies, mRNA and protein analysis of renal molecules involved in acid-base handling.

RESULTS

We demonstrate that rats with reduced kidney function as evident from lower creatinine clearance, lower haematocrit, higher plasma blood urea nitrogen, creatinine, phosphate and potassium had metabolic acidosis that could be aggravated by HCl acid loading. Urinary ammonium excretion was highly reduced whereas urinary pH was more acidic in CKD compared with control animals. The abundance of key enzymes and transporters of proximal tubular ammoniagenesis (phosphate-dependent glutaminase, PEPCK and SNAT3) and bicarbonate transport (NBCe1) was reduced in CKD compared with control animals. In the collecting duct, normal expression of the B1 H(+)-ATPase subunit is in agreement with low urinary pH. In contrast, the RhCG ammonia transporter, critical for the final secretion of ammonia into urine was strongly down-regulated in CKD animals.

CONCLUSION

In the Han:SPRD rat model for CKD, key molecules required for renal ammoniagenesis and ammonia excretion are highly down-regulated providing a possible molecular explanation for the development and maintenance of renal acidosis in CKD patients.

Building a network of ADPKD reference centres across Europe: the EuroCYST initiative

BACKGROUND

Autosomal dominant polycystic kidney disease (ADPKD) is the most common monogenic inherited kidney disease, affecting an estimated 600 000 individuals in Europe. The disease is characterized by age-dependent development of a multiple cysts in the kidneys, ultimately leading to end-stage renal failure and the need of renal replacement therapy in the majority of patients, typically by the fifth or sixth decade of life. The variable disease course, even within the same family, remains largely unexplained. Similarly, assessing disease severity and prognosis in an individual with ADPKD remains difficult. Epidemiological studies are limited due to the fragmentation of ADPKD research in Europe.

METHODS

The EuroCYST initiative aims: (i) to harmonize and develop common standards for ADPKD research by starting a collaborative effort to build a network of ADPKD reference centres across Europe and (ii) to establish a multicentric observational cohort of ADPKD patients. This cohort will be used to study factors influencing the rate of disease progression, disease modifiers, disease stage-specific morbidity and mortality, health economic issues and to identify predictive disease progression markers. Overall, 1100 patients will be enrolled in 14 study sites across Europe. Patients will be prospectively followed for at least 3 years. Eligible patients will not have participated in a pharmaceutical clinical trial 1 year before enrollment, have clinically proven ADPKD, an estimated glomerular filtration rate (eGFR) of 30 mL/min/1.73 m(2) and above, and be able to provide written informed consent. The baseline visit will include a physical examination and collection of blood, urine and DNA for biomarker and genetic studies. In addition, all participants will be asked to complete questionnaires detailing self-reported health status, quality of life, socioeconomic status, health-care use and reproductive planning. All subjects will undergo annual follow-up. A magnetic resonance imaging (MRI) scan will be carried out at baseline, and patients are encouraged to undergo a second MRI at 3-year follow-up for qualitative and quantitative kidney and liver assessments.

CONCLUSIONS

The ADPKD reference centre network across Europe and the observational cohort study will enable European ADPKD researchers to gain insights into the natural history, heterogeneity and associated complications of the disease as well as how it affects the lives of patients across Europe.

Excessive activation of the alternative complement pathway in autosomal dominant polycystic kidney disease

OBJECTIVES

The complement system is involved in many immune complex-mediated kidney diseases, yet its role in the pathogenesis of autosomal dominant polycystic kidney disease (ADPKD) has not been examined in detail.

METHODS AND RESULTS

Screening of the glycoproteome of urine samples from ADPKD patients revealed that levels of complement factor B (CFB), serpin peptidase inhibitor, complement component 1 inhibitor (SERPING1) and complement component 9 (C9) increased, whereas complement component 1, r subcomponent-like (C1RL), CD55 and CD59 levels decreased with disease progression. Immunostaining and Western blot analysis confirmed the enhanced expression of CFB and C9 in cystic kidneys from ADPKD patients. Immunostaining also showed that the expressions of CFB and C9 in renal biopsy tissues from patients with other types of chronic kidney disease were lower than in tissues from ADPKD patients. The effect of the complement inhibitor rosmarinic acid (RMA) was evaluated in Pkd1(-/-) mice and Han:SPRD Cy/+ rats. Compared with vehicle-treated Pkd1(-/-) animals, RMA-treated mice had significantly lower serum creatinine (-50%) and blood urea nitrogen (-78%) levels, two kidneys/body weight ratio (-60%) and renal cystic index (-60%). Similar results were found in Cy/+ rats. Lower numbers of Ki67-positive nuclei and inflammatory cells and reduced fibrosis were observed in both animal models upon treatment with RMA.

CONCLUSIONS

These results suggest that excessive activation of the alternative complement pathway is associated with ADPKD progression, probably mediated by cyst-lining epithelial cell proliferation, tubulointerstitial inflammatory cell infiltration and fibrosis. Targeting the complement system might represent a new therapeutic strategy for ADPKD.

Prognostic value and link to atrial fibrillation of soluble Klotho and FGF23 in hemodialysis patients

Deranged calcium-phosphate metabolism contributes to the burden of morbidity and mortality in dialysis patients. This study aimed to assess the association of the phosphaturic hormone fibroblast growth factor 23 (FGF23) and soluble Klotho with all-cause mortality. We measured soluble Klotho and FGF23 levels at enrolment and two weeks later in 239 prevalent hemodialysis patients. The primary hypothesis was that low Klotho and high FGF23 are associated with increased mortality. The association between Klotho and atrial fibrillation (AF) at baseline was explored as secondary outcome. AF was defined as presence of paroxysmal, persistent or permanent AF. During a median follow-up of 924 days, 59 (25%) patients died from any cause. Lower Klotho levels were not associated with mortality in a multivariable adjusted analysis when examined either on a continuous scale (HR 1.25 per SD increase, 95% CI 0.84–1.86) or in tertiles, with tertile 1 as the reference category (HR for tertile two 0.65, 95% CI 0.26–1.64; HR for tertile three 2.18, 95% CI 0.91–2.23). Higher Klotho levels were associated with the absence of AF in a muItivariable logistic regression analysis (OR 0.66 per SD increase, 95% CI 0.41–1.00). Higher FGF23 levels were associated with mortality risk in a multivariable adjusted analysis when examined either on a continuous scale (HR 1.45 per SD increase, 95% CI 1.05–1.99) or in tertiles, with the tertile 1 as the reference category (HR for tertile two 1.63, 95% CI 0.64–4.14; HR for tertile three 3.91, 95% CI 1.28–12.20). FGF23 but not Klotho levels are associated with mortality in hemodialysis patients. Klotho may be protective against AF.

Multicentre prospective validation of a urinary peptidome-based classifier for the diagnosis of type 2 diabetic nephropathy

BACKGROUND

Diabetic nephropathy (DN) is one of the major late complications of diabetes. Treatment aimed at slowing down the progression of DN is available but methods for early and definitive detection of DN progression are currently lacking. The 'Proteomic prediction and Renin angiotensin aldosterone system Inhibition prevention Of early diabetic nephRopathy In TYpe 2 diabetic patients with normoalbuminuria trial' (PRIORITY) aims to evaluate the early detection of DN in patients with type 2 diabetes (T2D) using a urinary proteome-based classifier (CKD273).

METHODS

In this ancillary study of the recently initiated PRIORITY trial we aimed to validate for the first time the CKD273 classifier in a multicentre (9 different institutions providing samples from 165 T2D patients) prospective setting. In addition we also investigated the influence of sample containers, age and gender on the CKD273 classifier.

RESULTS

We observed a high consistency of the CKD273 classification scores across the different centres with areas under the curves ranging from 0.95 to 1.00. The classifier was independent of age (range tested 16-89 years) and gender. Furthermore, the use of different urine storage containers did not affect the classification scores. Analysis of the distribution of the individual peptides of the classifier over the nine different centres showed that fragments of blood-derived and extracellular matrix proteins were the most consistently found.

CONCLUSION

We provide for the first time validation of this urinary proteome-based classifier in a multicentre prospective setting and show the suitability of the CKD273 classifier to be used in the PRIORITY trial.

Pain identifies squamous cell carcinoma in organ transplant recipients: the SCOPE-ITSCC PAIN study

Organ transplant recipients (OTR) are at high risk for cutaneous squamous cell carcinomas (SCC). We aimed to define clinically meaningful patient-reported warning signals predicting the presence of invasive SCC.Patient-reported signs and symptoms of 812 consecutively biopsied skin lesions from 410 OTR were determined by questionnaire and physical examination and related to the subsequent biopsy-proven diagnoses. Receiver-operating characteristic (ROC) curve analyses were used as a measure of distinction between the predictive values of patient-reported warning signals and the occurrence of SCC. Pain was an independent predictive patient-reported warning signal for a biopsy-proven invasive SCC. The odds ratio from the fully adjusted model predicting SCC was 4.4(95% confidence interval: 2.4–8.2). Higher scores on the visual analog scale (VAS) for pain were associated witha greater likelihood for the presence of SCC compared to none or mild pain. The for scores on the VAS from 1to 3, 4 to 6 and 7 to 10 were 4.9 (2.2–10.5), 2.3 (0.96–5.5)and 16.5 (3.6–75.8), respectively. Pain is the most powerful patient-reported warning signal for invasive cutaneous SCC in OTR. Empowerment of patients by education could accelerate diagnosis and treatment of cutaneous SCC.

[The educational website Dermaguard to prevent the incidence of skin cancer after transplantation]

Solid organ transplant recipients are highly susceptible to skin cancer. The major driving factors are immunosuppressive medication and ultraviolet light. Appropriate sun protection markedly reduces the development of skin cancer. Skin cancer recognized at an early stage can reliably be cured, and fatal outcomes can be prevented. The aim of this work is to educate organ transplant recipients and health care professionals involved in their care, to increase awareness of skin cancer in this high-risk population and thus to optimize the long-term outcome of patients with skin cancer. Our newly developed website provides free access to various educational materials, including leaflets, presentations and interactive elements using edutainment.

The role of phospholipase D in modulating the MTOR signaling pathway in polycystic kidney disease

The mammalian target of rapamycin (mTOR) signaling pathway is aberrantly activated in polycystic kidney disease (PKD). Emerging evidence suggests that phospholipase D (PLD) and its product phosphatidic acid (PA) regulate mTOR activity. In this study, we assessed in vitro the regulatory function of PLD and PA on the mTOR signaling pathway in PKD. We found that the basal level of PLD activity was elevated in PKD cells. Targeting PLD by small molecule inhibitors reduced cell proliferation and blocked mTOR signaling, whereas exogenous PA stimulated mTOR signaling and abolished the inhibitory effect of PLD on PKD cell proliferation. We also show that blocking PLD activity enhanced the sensitivity of PKD cells to rapamycin and that combining PLD inhibitors and rapamycin synergistically inhibited PKD cell proliferation. Furthermore, we demonstrate that targeting mTOR did not induce autophagy, whereas targeting PLD induced autophagosome formation. Taken together, our findings suggest that deregulated mTOR pathway activation is mediated partly by increased PLD signaling in PKD cells. Targeting PLD isoforms with pharmacological inhibitors may represent a new therapeutic strategy in PKD.

[Assessment of proteinuria]

Proteinuria is frequently found by general practitioners and is a possible sign of kidney disease. The insidious nature of many kidney diseases that develop without overt symptoms emphasize the clinical importance of urine analysis, both in screening and in monitoring of kidney pathology. Early detection of kidney disease plays a key role in preventing and progression of kidney disease. Thus, general practitioner can greatly contribute to early recognition and assessment of renal disease. Proteinuria may be benign or suggestive of glomerular disease. Patients with persistent proteinuria should be referred to a nephrologist for decisions regarding further management including renal biopsy. The standard urine dipstick detects only albumin and is not sensitive enough to detect non-albumins. Estimation of daily protein excretion using the total protein-to-creatinine ratio widely replaced the 24-hour urine measurement.

Urinary proteomic biomarkers for diagnosis and risk stratification of autosomal dominant polycystic kidney disease: a multicentric study

Treatment options for autosomal dominant polycystic kidney disease (ADPKD) will likely become available in the near future, hence reliable diagnostic and prognostic biomarkers for the disease are strongly needed. Here, we aimed to define urinary proteomic patterns in ADPKD patients, which aid diagnosis and risk stratification. By capillary electrophoresis online coupled to mass spectrometry (CE-MS), we compared the urinary peptidome of 41 ADPKD patients to 189 healthy controls and identified 657 peptides with significantly altered excretion, of which 209 could be sequenced using tandem mass spectrometry. A support-vector-machine based diagnostic biomarker model based on the 142 most consistent peptide markers achieved a diagnostic sensitivity of 84.5% and specificity of 94.2% in an independent validation cohort, consisting of 251 ADPKD patients from five different centers and 86 healthy controls. The proteomic alterations in ADPKD included, but were not limited to markers previously associated with acute kidney injury (AKI). The diagnostic biomarker model was highly specific for ADPKD when tested in a cohort consisting of 481 patients with a variety of renal and extrarenal diseases, including AKI. Similar to ultrasound, sensitivity and specificity of the diagnostic score depended on patient age and genotype. We were furthermore able to identify biomarkers for disease severity and progression. A proteomic severity score was developed to predict height adjusted total kidney volume (htTKV) based on proteomic analysis of 134 ADPKD patients and showed a correlation of r = 0.415 (p<0.0001) with htTKV in an independent validation cohort consisting of 158 ADPKD patients. In conclusion, the performance of peptidomic biomarker scores is superior to any other biochemical markers of ADPKD and the proteomic biomarker patterns are a promising tool for prognostic evaluation of ADPKD.

Secreted Klotho and FGF23 in chronic kidney disease Stage 1 to 5: a sequence suggested from a cross-sectional study

BACKGROUND

Klotho and fibroblast growth factor 23 (FGF23) are key regulators of mineral metabolism in renal insufficiency. FGF23 levels have been shown to increase early in chronic kidney disease (CKD); however, the corresponding soluble Klotho levels at the different CKD stages are not known.

METHODS

Soluble Klotho, FGF23, parathyroid hormone (PTH), 1,25-dihydroxy vitamin D(3) (1,25D) and other parameters of mineral metabolism were measured in an observational cross-sectional study in 87 patients. Locally weighted scatter plot smoothing function of these parameters were plotted versus estimated glomerular filtration rate (eGFR) to illustrate the pattern of the relationship. Linear and non-linear regression analyses were performed to estimate changes in mineral metabolism parameters per 1mL/min/1.73 m(2) decline.

RESULTS

In CKD 1-5, Klotho and 1,25D linearly decreased, whereas both FGF23 and PTH showed a baseline at early CKD stages and then a curvilinear increase. Crude mean Klotho level declined by 4.8 pg/mL (95% CI 3.5-6.2 pg/mL, P < 0.0001) and 1,25D levels by 0.30 ng/L (95% CI 0.18-0.41 ng/L, P < 0.0001) as GFR declined by 1 mL/min/1.73 m(2). After adjustment for age, gender, serum 25-hydroxyvitamin D levels and concomitant medications (calcium, supplemental vitamin D and calcitriol), we estimated that the mean Klotho change was 3.2 pg/mL (95% CI 1.2-5.2 pg/mL, P = 0.0019) for each 1 mL/min/1.73 m(2) GFR change. FGF23 departed from the baseline at an eGFR of 47 mL/min/1.73 m(2) (95% CI 39-56 mL/min/1.73 m(2)), whereas PTH departed at an eGFR of 34 mL/min/1.73 m(2) (95% CI 19-50 mL/min/1.73 m(2)).

CONCLUSIONS

Soluble Klotho and 1,25D levels decrease and FGF23 levels increase at early CKD stages, whereas PTH levels increase at more advanced CKD stages.

Low-dose oral sirolimus and the risk of menstrual-cycle disturbances and ovarian cysts: analysis of the randomized controlled SUISSE ADPKD trial

Sirolimus has been approved for clinical use in non proliferative and proliferative disorders. It inhibits the mammalian target of rapamycin (mTOR) signaling pathway which is also known to regulate ovarian morphology and function. Preliminary observational data suggest the potential for ovarian toxicity but this issue has not been studied in randomized controlled trials. We reviewed the self-reported occurrence of menstrual cycle disturbances and the appearance of ovarian cysts post hoc in an open label randomized controlled phase II trial conducted at the University Hospital Zürich between March 2006 and March 2010. Adult females with autosomal dominant polycystic kidney disease, an inherited kidney disease not known to affect ovarian morphology and function, were treated with 1.3 to 1.5 mg sirolimus per day for a median of 19 months (N = 21) or standard care (N = 18). Sirolimus increased the risk of both oligoamenorrhea (hazard ratio [HR] 4.3, 95% confidence interval [CI] 1.1 to 29) and ovarian cysts (HR 4.4, CI 1.1 to 26); one patient was cystectomized five months after starting treatment with sirolimus. We also studied mechanisms of sirolimus-associated ovarian toxicity in rats. Sirolimus amplified signaling in rat ovarian follicles through the pro-proliferative phosphatidylinositol 3-kinase pathway. Low dose oral sirolimus increases the risk of menstrual cycle disturbances and ovarian cysts and monitoring of sirolimus-associated ovarian toxicity is warranted and might guide clinical practice with mammalian target of rapamycin inhibitors.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00346918.

Quantitative BOLD response of the renal medulla to hyperoxic challenge at 1.5 T and 3.0 T

The aim of this study was to gage the magnitude of changes of the apparent renal medullary transverse relaxation time (ΔT(2)) induced by inhalation of pure oxygen (O(2) ) or carbogen (95% O(2) , 5% CO(2) ) versus baseline breathing of room air. Eight healthy volunteers underwent 2D multi-gradient echo MR imaging at 1.5 T and 3.0 T. Parametrical T(2) relaxation time maps were computed and average T(2) was measured in regions of interest placed in the renal medulla and cortex. The largest T(2) changes were measured in the renal medulla, with a relative ∆T(2) of 33.8 ± 22.0% (right medulla) and 34.7 ± 17.6% (left medulla) as compared to room air for oxygen breathing (p > 0.01), and 53.8 ± 23.9% and 53.5 ± 33.9% (p < 0.01) for carbogen breathing, respectively at 3 T. At 1.5 T, the corresponding values were 13.7 ± 18.5% and 24.1 ± 17.1% (p < 0.01) for oxygen breathing and 23.9 ± 17.2% and 38.9 ± 37.6% (p < 0.01) for carbogen breathing. As a result, we showed that renal medullary T(2) times responded strongly to inhalation of hyperoxic gases, which may be attributed to the hypoxic condition of the medulla and subsequent reduction in deoxyhemoglobin.

Sirolimus and secondary skin-cancer prevention in kidney transplantation

BACKGROUND

Transplant recipients in whom cutaneous squamous-cell carcinomas develop are at high risk for multiple subsequent skin cancers. Whether sirolimus is useful in the prevention of secondary skin cancer has not been assessed.

METHODS

In this multicenter trial, we randomly assigned transplant recipients who were taking calcineurin inhibitors and had at least one cutaneous squamous-cell carcinoma either to receive sirolimus as a substitute for calcineurin inhibitors (in 64 patients) or to maintain their initial treatment (in 56). The primary end point was survival free of squamous-cell carcinoma at 2 years. Secondary end points included the time until the onset of new squamous-cell carcinomas, occurrence of other skin tumors, graft function, and problems with sirolimus.

RESULTS

Survival free of cutaneous squamous-cell carcinoma was significantly longer in the sirolimus group than in the calcineurin-inhibitor group. Overall, new squamous-cell carcinomas developed in 14 patients (22%) in the sirolimus group (6 after withdrawal of sirolimus) and in 22 (39%) in the calcineurin-inhibitor group (median time until onset, 15 vs. 7 months; P=0.02), with a relative risk in the sirolimus group of 0.56 (95% confidence interval, 0.32 to 0.98). There were 60 serious adverse events in the sirolimus group, as compared with 14 such events in the calcineurin-inhibitor group (average, 0.938 vs. 0.250). There were twice as many serious adverse events in patients who had been converted to sirolimus with rapid protocols as in those with progressive protocols. In the sirolimus group, 23% of patients discontinued the drug because of adverse events. Graft function remained stable in the two study groups.

CONCLUSIONS

Switching from calcineurin inhibitors to sirolimus had an antitumoral effect among kidney-transplant recipients with previous squamous-cell carcinoma. These observations may have implications concerning immunosuppressive treatment of patients with cutaneous squamous-cell carcinomas. (Funded by Hospices Civils de Lyon and others; TUMORAPA ClinicalTrials.gov number, NCT00133887.).

Soluble klotho and autosomal dominant polycystic kidney disease

BACKGROUND AND OBJECTIVES

Fibroblast growth factor 23 (FGF23) levels are elevated in patients with autosomal dominant polycystic kidney disease (ADPKD) and X-linked hypophosphatemia (XLH), but only the latter is characterized by a renal phosphate wasting phenotype. This study explored potential mechanisms underlying resistance to FGF23 in ADPKD.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

FGF23 and klotho levels were measured, and renal phosphate transport was evaluated by calculating the ratio of the maximum rate of tubular phosphate reabsorption to GFR (TmP/GFR) in 99 ADPKD patients, 32 CKD patients, 12 XLH patients, and 20 healthy volunteers. ADPKD and CKD patients were classified by estimated GFR (CKD stage 1, ≥90 ml/min per 1.73 m(2); CKD stage 2, 60-89 ml/min per 1.73 m(2)).

RESULTS

ADPKD patients had 50% higher FGF23 levels than did XLH patients; TmP/GFR was near normal in most ADPKD patients and very low in XLH patients. Serum klotho levels were lowest in the ADPKD group, whereas the CKD and XLH groups and volunteers had similar levels. ADPKD patients with an apparent renal phosphate leak had two-fold higher klotho levels than those without. Serum klotho values correlated inversely with cyst volume and kidney growth.

CONCLUSIONS

Loss of klotho might be a consequence of cyst growth and constrain the phosphaturic effect of FGF23 in most patients with ADPKD. Normal serum klotho levels were associated with normal FGF23 biologic activity in all XLH patients and a minority of ADPKD patients. Loss of klotho and FGF23 increase appear to exceed and precede the changes that can be explained by loss of GFR in patients with ADPKD.

Reversal of UVA skin photosensitivity and DNA damage in kidney transplant recipients by replacing azathioprine

Azathioprine is associated with enhanced skin photosensitivity to ultraviolet A (UVA) and leads to incorporation of 6-thioguanine (6-TG) into DNA of dividing cells. Unlike canonical DNA, 6-TG DNA is damaged by UVA, which comprises more than 90% of the ultraviolet reaching earth. Skin photosensitivity to UVA and UVB was measured in 48 kidney transplant patients immunosuppressed either by azathioprine (n = 32) or mycophenolate (n = 16). In 23 patients, azathioprine was subsequently replaced by mycophenolate and skin photosensitivity, DNA 6-TG content in peripheral blood mononuclear cells, and susceptibility to UVA-induced DNA damage were monitored for up to 2 years. The mean minimal erythema dose to UVA on azathioprine was twofold lower than on mycophenolate. Three months after replacing azathioprine by mycophenolate mofetil, the minimal erythema dose to UVA had increased from 15 to 25 J/cm(2) (p < 0.001) accompanied by reduced DNA 6-TG content. P53 protein expression in irradiated skin indicated reduced susceptibility to UVA-induced DNA damage. 6-TG DNA in peripheral blood mononuclear cells remained measurable for over 2 years. Replacing azathioprine selectively reduced the skin photosensitivity to UVA, attenuated UVA-induced skin DNA damage, and is likely based on incorporated 6-TG in DNA.

Renal outcomes of agalsidase beta treatment for Fabry disease: role of proteinuria and timing of treatment initiation

BACKGROUND

The purpose of this study was to identify determinants of renal disease progression in adults with Fabry disease during treatment with agalsidase beta.

METHODS

Renal function was evaluated in 151 men and 62 women from the Fabry Registry who received agalsidase beta at an average dose of 1 mg/kg/2 weeks for at least 2 years. Patients were categorized into quartiles based on slopes of estimated glomerular filtration rate (eGFR) during treatment. Multivariate logistic regression analyses were used to identify factors associated with renal disease progression.

RESULTS

Men within the first quartile had a mean eGFR slope of -0.1 mL/min/1.73m(2)/year, whereas men with the most rapid renal disease progression (Quartile 4) had a mean eGFR slope of -6.7 mL/min/1.73m(2)/year. The risk factor most strongly associated with renal disease progression was averaged urinary protein:creatinine ratio (UP/Cr) ≥1 g/g (odds ratio 112, 95% confidence interval (95% CI) 4-3109, P = 0.0054). Longer time from symptom onset to treatment was also associated with renal disease progression (odds ratio 19, 95% CI 2-184, P = 0.0098). Women in Quartile 4 had the highest averaged UP/Cr (mean 1.8 g/g) and the most rapid renal disease progression: (mean slope -4.4 mL/min/1.73m(2)/year).

CONCLUSIONS

Adults with Fabry disease are at risk for progressive loss of eGFR despite enzyme replacement therapy, particularly if proteinuria is ≥1 g/g. Men with little urinary protein excretion and those who began receiving agalsidase beta sooner after the onset of symptoms had stable renal function. These findings suggest that early intervention may lead to optimal renal outcomes.

Anti-VEGF antibody treatment accelerates polycystic kidney disease

Polycystic kidney growth implies expansion of the vasculature, suggesting that vascular endothelial growth factor (VEGF)-dependent processes play a critical role and that VEGF is a putative therapeutic target. Whether an anti-VEGF antibody improves renal cystic disease has not been determined. We administrated 5 mg/kg B20.4.1, an anti-VEGF-A antibody, or vehicle intraperitoneally twice weekly to 4-wk-old male normal (+/+) and cystic (Cy/+) Han:SPRD rats for 6 wk. Renal function, urinary protein excretion, organ/body weight ratios, cyst volume, tubular epithelial cell (TEC) proliferation, renal VEGF, hypoxia-inducible factor (HIF)-1α and -2α expression, renal histology, and kidney hypoxia visualized by [(18)F]fluoromisonidazole positron emission tomography were assessed. The treated compared with untreated +/+ rats had lower TEC proliferation rates, whereas Cy/+ rats receiving B20.4.1 displayed an increased proximal TEC proliferation rate, causing enhanced cyst and kidney growth. The +/+ and Cy/+ rats receiving B20.4.1 had severe renal failure and extensive glomerular damage. Proteinuria, which was highest in anti-VEGF-treated Cy/+ and lowest in untreated normal littermates, was positively correlated with renal HIF-1α and negatively correlated with VEGF expression. The untreated Cy/+ vs. +/+ rats had higher overall [(18)F]fluoromisonidazole uptake. The +/+ rats receiving B20.4.1 vs. untreated had increased [(18)F]fluoromisonidazole uptake, whereas the uptake was unchanged among treated vs. untreated Cy/+ animals. In conclusion, B20.4.1 caused an exaggerated cystic response of the proximal tubules in cystic rats and severe kidney injury that was associated with low renal VEGF and high HIF-1α levels. Anti-VEGF drug therapy may therefore not be a treatment option for polycystic kidney disease.

A distinct urinary biomarker pattern characteristic of female Fabry patients that mirrors response to enzyme replacement therapy

Female patients affected by Fabry disease, an X-linked lysosomal storage disorder, exhibit a wide spectrum of symptoms, which renders diagnosis, and treatment decisions challenging. No diagnostic test, other than sequencing of the alpha-galactosidase A gene, is available and no biomarker has been proven useful to screen for the disease, predict disease course and monitor response to enzyme replacement therapy. Here, we used urine proteomic analysis based on capillary electrophoresis coupled to mass spectrometry and identified a biomarker profile in adult female Fabry patients. Urine samples were taken from 35 treatment-naïve female Fabry patients and were compared to 89 age-matched healthy controls. We found a diagnostic biomarker pattern that exhibited 88.2% sensitivity and 97.8% specificity when tested in an independent validation cohort consisting of 17 treatment-naïve Fabry patients and 45 controls. The model remained highly specific when applied to additional control patients with a variety of other renal, metabolic and cardiovascular diseases. Several of the 64 identified diagnostic biomarkers showed correlations with measures of disease severity. Notably, most biomarkers responded to enzyme replacement therapy, and 8 of 11 treated patients scored negative for Fabry disease in the diagnostic model. In conclusion, we defined a urinary biomarker model that seems to be of diagnostic use for Fabry disease in female patients and may be used to monitor response to enzyme replacement therapy.

Prognostic indicators of renal disease progression in adults with Fabry disease: natural history data from the Fabry Registry

BACKGROUND AND OBJECTIVES

These analyses were designed to characterize renal disease progression in untreated adults with Fabry disease.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Data from the Fabry Registry for 462 untreated adults (121 men and 341 women) who had at least two estimated GFR (eGFR) values over a span of ≥12 months before starting enzyme replacement therapy were included.

RESULTS

Most men (86 of 121, 71%) had more rapid loss of kidney function than the normal adult population (loss of eGFR > -1 ml/min per 1.73 m(2) per year), whereas fewer women (133 of 341, 39%) had rapid loss of kidney function. Patients with rapid progression had significantly higher mean averaged urinary protein to urinary creatinine ratios (UP/Cr) than patients with slower progression (1.5 versus 0.2 for men; 1.4 versus 0.5 for women; P < 0.0001). Patients were grouped into quartiles based on averaged UP/Cr; renal function in men declined more rapidly with higher UP/Cr, with the steepest declines observed in men with UP/Cr > 1.5 (mean eGFR slope, -5.6 ml/min per 1.73 m(2) per year; n = 30). eGFR slope declined more slowly in women, with the steepest declines observed in women with UP/Cr > 1.2 (mean eGFR slope, -1.3 ml/min per 1.73 m(2) per year; n = 85). Regression models of eGFR slope indicated that UP/Cr is the most important indicator of renal disease progression in adult Fabry patients. In women, lower baseline eGFR and age were also associated with renal disease progression. Women who had clinical events had more rapid loss of kidney function.

CONCLUSIONS

Urinary protein excretion is strongly associated with renal disease progression in men and women with Fabry disease.

Sirolimus and kidney growth in autosomal dominant polycystic kidney disease

BACKGROUND

In autosomal dominant polycystic kidney disease (ADPKD), aberrant activation of the mammalian target of rapamycin (mTOR) pathway is associated with progressive kidney enlargement. The drug sirolimus suppresses mTOR signaling.

METHODS

In this 18-month, open-label, randomized, controlled trial, we sought to determine whether sirolimus halts the growth in kidney volume among patients with ADPKD. We randomly assigned 100 patients between the ages of 18 and 40 years to receive either sirolimus (target dose, 2 mg daily) or standard care. All patients had an estimated creatinine clearance of at least 70 ml per minute. Serial magnetic resonance imaging was performed to measure the volume of polycystic kidneys. The primary outcome was total kidney volume at 18 months on blinded assessment. Secondary outcomes were the glomerular filtration rate and urinary albumin excretion rate at 18 months.

RESULTS

At randomization, the median total kidney volume was 907 cm3 (interquartile range, 577 to 1330) in the sirolimus group and 1003 cm3 (interquartile range, 574 to 1422) in the control group. The median increase over the 18-month period was 99 cm3 (interquartile range, 43 to 173) in the sirolimus group and 97 cm3 (interquartile range, 37 to 181) in the control group. At 18 months, the median total kidney volume in the sirolimus group was 102% of that in the control group (95% confidence interval, 99 to 105; P=0.26). The glomerular filtration rate did not differ significantly between the two groups; however, the urinary albumin excretion rate was higher in the sirolimus group.

CONCLUSIONS

In adults with ADPKD and early chronic kidney disease, 18 months of treatment with sirolimus did not halt polycystic kidney growth. (Funded by Wyeth and others; ClinicalTrials.gov number, NCT00346918.)

[Autosomal dominant polycystic kidney disease (ADPKD): rapamycin as a new treatment option]

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by the massive enlargement of both kidneys caused by numerous cysts. The cyst formation begins in utero and the continuous growth of cysts leads to compression and destruction of non-cystic renal parenchyma, so that finally a kidney replacement in the 5th to 6th decade of life is necessary. So far there is no therapy that halts disease progression. Animal data show that pharmacological inhibition of a central regulator of cell proliferation, the so-called mammalian target of rapamycin (mTOR), slows disease progression. This overview provides an insight into the disease and the specific mTOR inhibitor sirolimus, which is currently tested in clinical trials.

Pulse mTOR inhibitor treatment effectively controls cyst growth but leads to severe parenchymal and glomerular hypertrophy in rat polycystic kidney disease

The efficacy of mammalian target of rapamycin (mTOR) inhibitors is currently tested in patients affected by autosomal dominant polycystic kidney disease. Treatment with mTOR inhibitors has been associated with numerous side effects. However, the renal-specific effect of mTOR inhibitor treatment cessation in polycystic kidney disease is currently unknown. Therefore, we compared pulse and continuous everolimus treatment in Han:SPRD rats. Four-week-old male heterozygous polycystic and wild-type rats were administered everolimus or vehicle by gavage feeding for 5 wk, followed by 7 wk without treatment, or continuously for 12 wk. Cessation of everolimus did not result in the appearance of renal cysts up to 7 wk postwithdrawal despite the reemergence of S6 kinase activity coupled with an overall increase in cell proliferation. Pulse everolimus treatment resulted in striking noncystic renal parenchymal enlargement and glomerular hypertrophy that was not associated with compromised kidney function. Both treatment regimens ameliorated kidney function, preserved the glomerular-tubular connection, and reduced proteinuria. Pulse treatment at an early age delays cyst development but leads to striking glomerular and parenchymal hypertrophy. Our data might have an impact when long-term treatment using mTOR inhibitors in patients with autosomal dominant polycystic kidney disease is being considered.