Peritoneal Dialysis Aggravates and Accelerates Atherosclerosis in Uremic ApoE-/- Mice.

BACKGROUND: Atherosclerosis is highly prevalent in people with chronic kidney disease (CKD), including those receiving peritoneal dialysis (PD). Although it is lifesaving, PD induces profound systemic inflammation, which may aggravate atherosclerosis. Therefore, the hypothesis is that this PD-induced inflammation aggravates atherosclerosis via immune cell activation. METHODS AND RESULTS: ApoE-/- mice were subjected to a 5/6 nephrectomy to induce CKD. Three weeks later, mice were fed a high-cholesterol diet. Half of the nephrectomized mice then received daily peritoneal infusions of 3.86% Physioneal for 67 further days (CKD+PD) until the end of the experiment, and were compared with mice without CKD. Sham operated and PD-only mice were additional controls. CKD+PD mice displayed more severe atherosclerotic disease than control mice. Plaque area increased, and plaques were more advanced with a vulnerable phenotype typified by decreased collagen content and decreased fibrous cap thickness. Increased CD3+ T-cell numbers were present in plaques and perivascular adipose tissue of CKD and CKD+PD mice. Plaques of CKD+PD mice contained more iNOS+ immune cells. Spleens of CKD+PD mice showed more CD4+ central memory, terminally differentiated type 1 T-helper (Th1), Th17, and CX3C motif chemokine receptor 1+ (CX3CR1) CD4+ T-cells with less regulatory and effector T-cells. CONCLUSIONS: PD-fluid exposure in uremic mice potentiates systemic and vascular T-cell-driven inflammation and aggravates atherosclerosis. PD polarized CD4+ T-cells toward an inflammatory Th1/Th17 phenotype, and increased CX3CR1+ CD4+ T-cells, which are associated with vascular homing in CKD-associated atherosclerosis. Targeting CD4+ T-cell activation and CX3CR1+ polarization has the potential to attenuate atherosclerosis in PD patients.

[Estimating glomerular filtration rate]. / Het schatten van de glomerulaire filtratiesnelheid.

Almost all laboratories in The Netherlands report an estimated glomerular filtration rate (eGFR) whenever a value for plasma creatinine is requested. This formula is based on gender and age, besides the plasma creatinine concentration, and sometimes also a correction for race is applied. While this GFR reporting improved the recognition of chronic kidney disease, the formulas used have intrinsic limitations. Moreover, recently a novel formula that obviates the need for a correction factor for race has been proposed. In this article the strengths and weaknesses of plasma creatinine and formulas based on that are discussed, following ten frequently asked questions.

Prevalence of chronic kidney disease in the Netherlands and its cardiovascular and renal complications.

BACKGROUND: Knowledge on prevalence, comorbidities and consequences of chronic kidney disease (CKD) is mandatory to estimate the potential of cardiovascular risk management on a population level. We studied the prevalence of CKD with or without type 2 diabetes mellitus (T2D) and/or heart failure and its cardiorenal complications in The Netherlands. METHODS: A descriptive cross-sectional and longitudinal cohort study was performed, using data from the Dutch PHARMO Data Network. Prevalence of CKD at a single time point was determined by a recorded diagnosis or by ≥ 2 estimated glomerular filtration rate (eGFR) measurements and urine albumin/creatinine ratio (UACR) that define CKD. A representative group of adults with CKD was included in a longitudinal analysis to study cardiorenal complications. Those were followed until first complication, end of study or death, whichever occurred first. RESULTS: The prevalence of CKD was 8.9% in a representative population of 2,187,962 adult Dutch individuals. The average age of persons with CKD was 72 years, 57% were female, 19.9% had T2D, 7.7% heart failure, and 3.0% both T2D and heart failure. In the longitudinal analysis, cerebrovascular events (11/1,000 person-years), hospitalizations for heart failure (10/1,000 person-years), myocardial infarction (5.5/1,000 person-years), and hospitalization for CKD (6.2/1,000 person-years) were the most common first cardiorenal complications. People with CKD with T2D and/or heart failure generally had higher rates of cardiovascular or renal complications or mortality than people with CKD without these comorbidities. CONCLUSION: The prevalence of CKD in The Netherlands is 8.9%. People with T2D or heart failure, or both, in addition to CKD, had numerically higher mortality and cardiorenal complication rates than people without these comorbidities. Optimizing up-to-date cardiovascular risk management in these high-risk individuals may provide health benefits.

Can we reverse arterial stiffness by intervening on CKD-MBD biomarkers?

The increased cardiovascular risk of chronic kidney disease may in part be the consequence of arterial stiffness, a typical feature of kidney failure. Deranged homeostasis of minerals and hormones involved (CKD-MBD), are also strongly associated with this increased risk. It is well established that CKD-MBD is a main driver of vascular calcification, which in turn worsens arterial stiffness. However, there are other contributors to arterial stiffness in CKD than calcification. An overlooked possibility is that CKD-MBD may have detrimental effects on this potentially better modifiable component of arterial stiffness. In this review, the individual contributions of short-term changes in calcium, phosphate, PTH, vitamin D, magnesium, and FGF23 to arterial stiffness, in most studies assessed as pulse wave velocity, is summarized. Indeed, there is evidence from both observational studies and interventional trials that higher calcium concentrations can worsen arterial stiffness. This, however, has not been shown for phosphate, and it seems unlikely that, apart from being a contributor to vascular calcification and having effects on the microcirculation, phosphate has no acute effect on large artery stiffness. Several interventional studies, both by infusing PTH and by abrupt lowering PTH by calcimimetics or surgery, virtually ruled out direct effects on large artery stiffness. A well-designed trial using both active and nutritional vitamin D as intervention found a beneficial effect for the latter. Unfortunately, the study had a baseline imbalance and other studies did not support its finding. Both magnesium and FGF23 do not seem do modify central arterial stiffness.

Vitamin D supplementation in people with chronic kidney disease.

Vitamin D supplements have long been advocated for people with chronic kidney disease based on data from observational studies among the general population and people with chronic kidney disease. These data consistently suggested that higher circulating concentrations of 25-hydroxyvitamin D are associated with improved fracture, cardiovascular, cancer, and mortality outcomes. In the past few years, large clinical trials have been conducted to assess the effects of vitamin D supplements on a range of clinically relevant outcomes. Most of these studies were performed in the general population, but they also enrolled people with chronic kidney disease. Virtually all of these trials were negative and contradicted the observational data. In this review, the key observational data and clinical trials are summarized, and potential explanations for the discrepancies between these studies are discussed.

Lower accuracy of testosterone, cortisol, and free T4 measurements using automated immunoassays in people undergoing hemodialysis.

OBJECTIVES: Hormone measurements using automated immunoassays (IAs) can be affected by the sample matrix. Liquid chromatography tandem-mass spectrometry (LC-MS/MS) is less affected by these matrix effects. In clinical laboratories, testosterone, cortisol and, free thyroxine (FT4) are often measured using IAs. Renal failure alters serum composition in blood samples from people undergoing hemodialysis (HDp) and have, therefore, a complex serum constitution compared to healthy controls (HC). The goal of this study was to investigate the accuracy of testosterone, cortisol, and FT4 measurements in samples of HDp and to get more insight in the interfering factors. METHODS: Thirty serum samples from HDp and HC were collected to measure testosterone, cortisol, and FT4 using a well standardized isotope dilution (ID)-LC-MS/MS method and 5 commercially available automated IAs (Alinity, Atellica, Cobas, Lumipulse, UniCel DXI). Method comparisons between LC-MS/MS and IAs were performed using both HDp and HC samples. RESULTS: Average bias from the LC-MS/MS was for testosterone, cortisol, and FT4 immunoassays respectively up to 92, 7-47 and 16-27% more in HDp than in HC samples and was IA dependent. FT4 IA results were falsely decreased in HDp samples, whereas cortisol and testosterone concentrations in females were predominantly falsely increased. Correlation coefficients between LC-MS/MS and IA results were lower in HDp compared to HC samples. CONCLUSIONS: Several IAs for testosterone (in women), cortisol, and FT4 are less reliable in the altered serum matrix of samples of HDp than in HC. Medical and laboratory specialists should be aware of these pitfalls in this specific population.

Magnesium Administration in Chronic Kidney Disease.

Awareness of the clinical relevance of magnesium in medicine has increased over the last years, especially for people with chronic kidney disease (CKD), due to magnesium's role in vascular calcification and mineral metabolism. The inverse association between serum magnesium and clinically relevant, adverse outcomes is well-established in people with CKD. Subsequent intervention studies have focused on the effect of magnesium administration, mainly in relation to cardiovascular diseases, mineral bone metabolism, and other metabolic parameters. The most commonly used routes of magnesium administration are orally and by increasing dialysate magnesium. Several oral magnesium formulations are available and the daily dosage of elemental magnesium varies highly between studies, causing considerable heterogeneity. Although data are still limited, several clinical studies demonstrated that magnesium administration could improve parameters of vascular function and calcification and mineral metabolism in people with CKD. Current clinical research has shown that magnesium administration in people with CKD is safe, without concerns for severe hypermagnesemia or negative interference with bone metabolism. It should be noted that there are several ongoing magnesium intervention studies that will contribute to the increasing knowledge on the potential of magnesium administration in people with CKD.

Magnesium in chronic haemodialysis (MAGIC-HD): a study protocol for a randomised controlled trial to determine feasibility and safety of using increased dialysate magnesium concentrations to increase plasma magnesium concentrations in people treated with haemodialysis.

INTRODUCTION: People treated with haemodialysis are at increased risk for all-cause and cardiovascular mortality. Plasma magnesium concentration has been inversely associated with these risks. Therefore, plasma magnesium may be a new modifiable risk factor and an increase of dialysate magnesium concentration may be an easy, safe and effective way to increase plasma magnesium concentrations. Detailed information on modulating dialysate magnesium concentrations is limited in literature. Primary objective of this study is to determine the safety and feasibility to increase plasma magnesium concentrations in people treated with haemodialysis by means of sequentially increasing concentration of magnesium in the dialysate. METHODS AND ANALYSIS: In this randomised double-blinded standard of care controlled trial, 53 persons treated with haemodialysis will be randomly allocated 2:1 to either a stepwise individually titrated increase of dialysate magnesium concentration from 0.50 to 0.75 to 1.00 mmol/L during 8 weeks, or a standard dialysate magnesium concentration of 0.50 mmol/L. Other study measurements include dietary records, questionnaires, ECG, Holter registration and pulse wave velocity. The primary endpoint is predialysis plasma magnesium after the long interdialytic interval at the end of week 8. In addition, the predictive effect of dialysate magnesium concentration and other baseline parameters and dialysis characteristics on plasma magnesium concentration will be explored using linear mixed models. Safety endpoint is defined by the occurrence of hypermagnesemia above 1.25 mmol/L, or bradycardia or prolonged QTc interval detected on the ECG. ETHICS AND DISSEMINATION: The study is conducted in accordance with the declaration of Helsinki as revised in 2013 and was approved by the Ethical Committee of the VU University Medical Centre. The results of the study will be disseminated by publication in peer-reviewed scientific journals and presentation at national or international conferences in the field of interest. TRIAL REGISTRATION NUMBER: NTR6568/NL6393.

Safety and Effectiveness of Difelikefalin in Patients With Moderate-to-Severe Pruritus Undergoing Hemodialysis: An Open-Label, Multicenter Study.

Rationale & Objective: Individuals with chronic kidney disease frequently suffer from chronic kidney disease-associated pruritus (CKD-aP), impacting sleep quality and quality of life (QoL) and increasing the likelihood of depression. Difelikefalin is a kappa-opioid receptor agonist recently approved in the United States for the treatment of moderate-to-severe CKD-aP in hemodialysis patients. Study 3105 was conducted to further assess the safety of difelikefalin and the effects on pruritus and QoL. Study Design: Open-label, multicenter, single-arm intervention trial. Setting & Participants: Maintenance hemodialysis patients with moderate-to-severe CKD-aP at enrollment. Intervention: Intravenous difelikefalin 0.5 µg/kg after each hemodialysis session for 12 weeks. Outcomes: The primary outcome was safety of difelikefalin. Secondary outcomes included: effectiveness of reducing itch intensity, assessed by the Worst Itching Intensity Numerical Rating Scale (WI-NRS); improving itch-related QoL, assessed with 5-D itch and Skindex-10 scales; and improvement of sleep, assessed with the Sleep Quality Numerial Rating Scale. Clinically meaningful thresholds for improvement in itch and QoL were previously established in this population. Results: Among 222 participants with baseline WI-NRS ≥5, mean [standard deviation] WI-NRS was 7.6 [1.3], mean age 58 years, 55% were male, and mean dialysis duration was 5.9 years; 197 participants (89%) completed treatment. Treatment-related treatment-emergent adverse events were reported in 16 participants (7.2%); those most commonly reported were somnolence (1.8%), hypoesthesia (1.4%), nausea (0.9%), and dizziness (0.9%). No deaths or serious treatment-emergent adverse events were considered treatment-related. Clinically meaningful reduction in itch intensity (≥3-point improvement) was reported by 74% of participants, with 70% and 63% also reporting a clinically relevant improvement in QoL as measured by 5-D itch and Skindex-10. Sleep quality improvement (≥3-point reduction on the Numerical Rating Scale) was reported in 66% of participants. Limitations: No placebo control group. Conclusions: Difelikefalin was well tolerated, and treatment was associated with clinically meaningful improvements in itch intensity and itch-related QoL measures as well as improvements in sleep quality among individuals receiving hemodialysis who had moderate-to-severe CKD-aP, providing important insights into expected real-world effectiveness. Funding: Cara Therapeutics. Trial Registration: NCT03998163.

Reversal Of Arterial Disease by modulating Magnesium and Phosphate (ROADMAP-study): rationale and design of a randomized controlled trial assessing the effects of magnesium citrate supplementation and phosphate-binding therapy on arterial stiffness in moderate chronic kidney disease.

BACKGROUND: Arterial stiffness and calcification propensity are associated with high cardiovascular risk and increased mortality in chronic kidney disease (CKD). Both magnesium and phosphate are recognized as modulators of vascular calcification and chronic inflammation, both features of CKD that contribute to arterial stiffness. In this paper, we outline the rationale and design of a randomized controlled trial (RCT) investigating whether 24 weeks of oral magnesium supplementation with or without additional phosphate-binding therapy can improve arterial stiffness and calcification propensity in patients with stage 3-4 CKD. METHODS: In this multi-center, placebo-controlled RCT, a total of 180 participants with an estimated glomerular filtration rate of 15 to 50 ml/min/1.73 m2 without phosphate binder therapy will be recruited. During the 24 weeks intervention, participants will be randomized to one of four intervention groups to receive either magnesium citrate (350 mg elemental magnesium/day) or placebo, with or without the addition of the phosphate binder sucroferric oxyhydroxide (1000 mg/day). Primary outcome of the study is the change of arterial stiffness measured by the carotid-femoral pulse wave velocity over 24 weeks. Secondary outcomes include markers of calcification and inflammation, among others calcification propensity (T50) and high-sensitivity C-reactive protein. As explorative endpoints, repeated 18F-FDG and 18F-NaF PET-scans will be performed in a subset of participants (n = 40). Measurements of primary and secondary endpoints are performed at baseline, 12 and 24 weeks. DISCUSSION: The combined intervention of magnesium citrate supplementation and phosphate-lowering therapy with sucroferric oxyhydroxide, in stage 3-4 CKD patients without overt hyperphosphatemia, aims to modulate the complex and deregulated mineral metabolism leading to vascular calcification and arterial stiffness and to establish to what extent this is mediated by T50 changes. The results of this combined intervention may contribute to future early interventions for CKD patients to reduce the risk of CVD and mortality. TRIAL REGISTRATION: Netherlands Trial Register, NL8252 (registered December 2019), EU clinical Trial Register 2019-001306-23 (registered November 2019).

Prevalence, outcomes, and cost of chronic kidney disease in a contemporary population of 2·4 million patients from 11 countries: The CaReMe CKD study.

Background: Digital healthcare systems data could provide insights into the global prevalence of chronic kidney disease (CKD). We designed the CaReMe CKD study to estimate the prevalence, key clinical adverse outcomes and costs of CKD across 11 countries. Methods: Individual-level data of a cohort of 2·4 million contemporaneous CKD patients was obtained from digital healthcare systems in participating countries using a pre-specified common protocol; summarized using random effects meta-analysis. CKD and its stages were defined in accordance with current Kidney Disease: Improving Global Outcomes (KDIGO) criteria. CKD was defined by laboratory values or by a diagnosis code. Findings: The pooled prevalence of possible CKD was 10·0% (95% confidence interval 8.5‒11.4; mean pooled age 75, 53% women, 38% diabetes, 60% using renin-angiotensin-aldosterone system inhibitors). Two out of three CKD patients identified by laboratory criteria did not have a corresponding CKD-specific diagnostic code. Among CKD patients identified by laboratory values, the majority (42%) were in KDIGO stage 3A; and this fraction was fairly consistent across countries. The share with CKD based on urine albumin-creatinine ratio (UACR) alone (KDIGO stages one and two) was 29%, with a substantial heterogeneity between countries. Adverse events were common; 6·5% were hospitalized for CKD or heart failure, and 6·2% died, annually. Costs for renal events and heart failure were consistently higher than costs for atherosclerotic events in CKD patients across all countries. Interpretation: We estimate that CKD is present in one out of ten adults. These individuals experience significant adverse outcomes with associated costs. The prevalence of CKD is underestimated when using diagnostic codes alone. There is considerable public health potential in diagnosing CKD and providing treatments to those currently undiagnosed. Funding: The study was sponsored by AstraZeneca.

Shedding Light on the Complex Regulation of FGF23.

Early research has suggested a rather straightforward relation between phosphate exposure, increased serum FGF23 (Fibroblast Growth Factor 23) concentrations and clinical endpoints. Unsurprisingly, however, subsequent studies have revealed a much more complex interplay between autocrine and paracrine factors locally in bone like PHEX and DMP1, concentrations of minerals in particular calcium and phosphate, calciprotein particles, and endocrine systems like parathyroid hormone PTH and the vitamin D system. In addition to these physiological regulators, an expanding list of disease states are shown to influence FGF23 levels, usually increasing it, and as such increase the burden of disease. While some of these physiological or pathological factors, like inflammatory cytokines, may partially confound the association of FGF23 and clinical endpoints, others are in the same causal path, are targetable and hence hold the promise of future treatment options to alleviate FGF23-driven toxicity, for instance in chronic kidney disease, the FGF23-associated disease with the highest prevalence by far. These factors will be reviewed here and their relative importance described, thereby possibly opening potential means for future therapeutic strategies.

Dietary magnesium supplementation inhibits abdominal vascular calcification in an experimental animal model of chronic kidney disease.

BACKGROUND: Vascular calcification is a key process involved in cardiovascular morbidity and mortality in patients with chronic kidney disease (CKD). Magnesium supplementation may counteract vascular calcification. In this study we aimed to determine whether increased dietary magnesium intake inhibits vascular calcification in CKD in vivo and explore the mechanisms underlying these effects. METHODS: Sprague Dawley rats were partially nephrectomized and fed a diet with high phosphate and either high or normal magnesium content for 16 weeks. The primary outcome was the tissue calcium content of the aorta in the high versus normal dietary magnesium group. In addition, we analysed plasma mineral concentrations, aortic vascular calcification identified with von Kossa staining, calcium apposition time and aortic expression of genes related to vascular calcification. RESULTS: The number of animals in the highest tissue calcium content tertile was significantly lower in the abdominal aorta [1 (10%) versus 6 (55%); P = .03] in the high versus normal dietary magnesium group, but did not differ in the aortic arch and thoracic aorta. Von Kossa staining and calcium apposition time corresponded to these results. The median tissue calcium content was not significantly different between the groups. Serum phosphate concentrations and expression of osteogenic markers in the aorta did not differ between the groups. CONCLUSIONS: This study demonstrates that increased dietary magnesium inhibits abdominal vascular calcification in an experimental animal model of CKD in vivo. These are promising results for CKD patients and further study is needed to identify the mechanisms involved and to determine the clinical relevance in patients.

Magnesium to prevent kidney disease-associated vascular calcification: crystal clear?

Vascular calcification is a prognostic marker for cardiovascular mortality in chronic kidney disease (CKD) patients. In these patients, magnesium balance is disturbed, mainly due to limited ultrafiltration of this mineral, changes in dietary intake and the use of diuretics. Observational studies in dialysis patients report that a higher blood magnesium concentration is associated with reduced risk to develop vascular calcification. Magnesium prevents osteogenic vascular smooth muscle cell transdifferentiation in in vitro and in vivo models. In addition, recent studies show that magnesium prevents calciprotein particle maturation, which may be the mechanism underlying the anti-calcification properties of magnesium. Magnesium is an essential protective factor in the calcification milieu, which helps to restore the mineral-buffering system that is overwhelmed by phosphate in CKD patients. The recognition that magnesium is a modifier of calciprotein particle maturation and mineralization of the extracellular matrix renders it a promising novel clinical tool to treat vascular calcification in CKD. Consequently, the optimal serum magnesium concentration for patients with CKD may be higher than in the general population.

Magnesium intake and vascular structure and function: the Hoorn Study.

PURPOSE: Circulating and dietary magnesium have been shown to be inversely associated with the prevalence of cardiovascular disease (CVD) and mortality in both high and low-risk populations. We aimed to examine the association between dietary magnesium intake and several measures of vascular structure and function in a prospective cohort. METHODS: We included 789 participants who participated in the vascular screening sub-cohort of the Hoorn Study, a population-based, prospective cohort study. Baseline dietary magnesium intake was estimated with a validated food frequency questionnaire and categorised in energy-adjusted magnesium intake tertiles. Several measurements of vascular structure and function were performed at baseline and most measurements were repeated after 8 years of follow-up (n = 432). Multivariable linear and logistic regression was performed to study the cross-sectional and longitudinal associations of magnesium intake and intima-media thickness (IMT), augmentation index (Aix), pulse wave velocity (PWV), flow-mediated dilatation (FMD), and peripheral arterial disease (PAD). RESULTS: Mean absolute magnesium intake was 328 ± 83 mg/day and prior CVD and DM2 was present in 55 and 41% of the participants, respectively. Multivariable regression analyses did not demonstrate associations between magnesium intake and any of the vascular outcomes. Participants in the highest compared to the lowest magnesium intake tertile demonstrated in fully adjusted cross-sectional analyses a PWV of -0.21 m/s (95% confidence interval -1.95, 1.52), a FMD of -0.03% (-0.89, 0.83) and in longitudinal analyses an IMT of 0.01 mm (-0.03, 0.06), an Aix of 0.70% (-1.69, 3.07) and an odds ratio of 0.84 (0.23, 3.11) for PAD CONCLUSION: We did not find associations between dietary magnesium intake and multiple markers of vascular structure and function, in either cross-sectional or longitudinal analyses.

Combining phosphate binder therapy with vitamin K2 inhibits vascular calcification in an experimental animal model of kidney failure.

BACKGROUND: Hyperphosphataemia is strongly associated with cardiovascular disease and mortality. Recently, phosphate binders (PBs), which are used to bind intestinal phosphate, have been shown to bind vitamin K, thereby potentially aggravating vitamin K deficiency. This vitamin K binding by PBs may offset the beneficial effects of phosphate reduction in reducing vascular calcification (VC). Here we assessed whether combining PBs with vitamin K2 supplementation inhibits VC. METHODS: We performed 3/4 nephrectomy in rats, after which warfarin was given for 3 weeks to induce vitamin K deficiency. Next, animals were fed a high phosphate diet in the presence of low or high vitamin K2 and were randomized to either control or one of four different PBs for 8 weeks. The primary outcome was the amount of thoracic and abdominal aorta VC measured by high-resolution micro-computed tomography (µCT). Vitamin K status was measured by plasma MK7 levels and immunohistochemically analysed in vasculature using uncarboxylated matrix Gla protein (ucMGP) specific antibodies. RESULTS: The combination of a high vitamin K2 diet and PB treatment significantly reduced VC as measured by µCT for both the thoracic (P = 0.026) and abdominal aorta (P = 0.023), compared with MK7 or PB treatment alone. UcMGP stain was significantly more present in the low vitamin K2-treated groups in both the thoracic (P < 0.01) and abdominal aorta (P < 0.01) as compared with high vitamin K2-treated groups. Moreover, a high vitamin K diet and PBs led to reduced vascular oxidative stress. CONCLUSION: In an animal model of kidney failure with vitamin K deficiency, neither PB therapy nor vitamin K2 supplementation alone prevented VC. However, the combination of high vitamin K2 with PB treatment significantly attenuated VC.

Real-world safety and effectiveness of sucroferric oxyhydroxide for treatment of hyperphosphataemia in dialysis patients: a prospective observational study.

BACKGROUND: The iron-based phosphate binder (PB), sucroferric oxyhydroxide (SFOH), is indicated to control serum phosphorus levels in patients with chronic kidney disease on dialysis. METHODS: This non-interventional, prospective, multicentre, cohort study conducted in seven European countries evaluated the safety and effectiveness of SFOH in dialysis patients with hyperphosphataemia in routine practice. Safety outcomes included adverse drug reactions (ADRs) and changes in iron-related parameters. SFOH effectiveness was evaluated by changes-from-baseline (BL) in serum phosphorus and percentage of patients achieving in-target phosphorus levels. RESULTS: The safety analysis set included 1365 patients (mean observation: 420.3 ± 239.3 days). Overall, 682 (50.0%) patients discontinued the study. Mean SFOH dose during the observation period was 1172.7 ± 539.9 mg (2.3 pills/day). Overall, 617 (45.2%) patients received concomitant PB(s) during SFOH treatment. ADRs and serious ADRs were observed for 531 (38.9%) and 26 (1.9%) patients. Most frequent ADRs were diarrhoea (194 patients, 14.2%) and discoloured faeces (128 patients, 9.4%). Diarrhoea generally occurred early during SFOH treatment and was mostly mild and transient. Small increases from BL in serum ferritin were observed (ranging from +12 to +75 µg/L). SFOH treatment was associated with serum phosphorus reductions (6.3 ± 1.6 mg/dL at BL versus 5.3 ± 1.8 mg/dL at Month 30; ΔBL: -1.0 mg/dL, P < 0.01). Percentage of patients achieving serum phosphorus ≤4.5 mg/dL increased from 12.0% at BL to 34.8% at Month 30, while the percentage achieving serum phosphorus ≤5.5 mg/dL increased from 29.9% to 63.0%. CONCLUSIONS: SFOH has a favourable safety and tolerability profile in a real-world setting, consistent with results of the Phase 3 study. Moreover, SFOH improved serum phosphorus control with a low daily pill burden.

Preservation of renal endothelial integrity and reduction of renal edema by aprotinin does not preserve renal perfusion and function following experimental cardiopulmonary bypass.

BACKGROUND: Acute kidney injury is a severe complication following cardiopulmonary bypass (CPB) and is associated with capillary leakage and microcirculatory perfusion disturbances. CPB-induced thrombin release results in capillary hyperpermeability via activation of protease-activated receptor 1 (PAR1). We investigated whether aprotinin, which is thought to prevent thrombin from activating PAR1, preserves renal endothelial structure, reduces renal edema and preserves renal perfusion and reduces renal injury following CPB. METHODS: Rats were subjected to CPB after treatment with 33.000 KIU/kg aprotinin (n = 15) or PBS (n = 15) as control. A secondary dose of 33.000 KIU/kg aprotinin was given 60 min after initiation of CPB. Cremaster and renal microcirculatory perfusion were assessed using intravital microscopy and contrast echography before CPB and 10 and 60 min after weaning from CPB. Renal edema was determined by wet/dry weight ratio and renal endothelial structure by electron microscopy. Renal PAR1 gene and protein expression and markers of renal injury were determined. RESULTS: CPB reduced cremaster microcirculatory perfusion by 2.5-fold (15 (10-16) to 6 (2-10) perfused microvessels, p < 0.0001) and renal perfusion by 1.6-fold (202 (67-599) to 129 (31-292) au/sec, p = 0.03) in control animals. Both did not restore 60 min post-CPB. This was paralleled by increased plasma creatinine (p < 0.01), neutrophil gelatinase-associated lipocalin (NGAL; p = 0.003) and kidney injury molecule-1 (KIM-1; p < 0.01). Aprotinin treatment preserved cremaster microcirculatory perfusion following CPB (12 (7-15) vs. 6 (2-10) perfused microvessels, p = 0.002), but not renal perfusion (96 (35-313) vs. 129 (31-292) au/s, p > 0.9) compared to untreated rats. Aprotinin treatment reduced endothelial gap formation (0.5 ± 0.5 vs. 3.1 ± 1.4 gaps, p < 0.0001), kidney wet/dry weight ratio (4.6 ± 0.2 vs. 4.4 ± 0.2, p = 0.046), and fluid requirements (3.9 ± 3.3 vs. 7.5 ± 3.0 ml, p = 0.006) compared to untreated rats. In addition, aprotinin treatment reduced tubulointerstitial neutrophil influx by 1.7-fold compared to untreated rats (30.7 ± 22.1 vs. 53.2 ± 17.2 neutrophil influx/section, p = 0.009). No differences were observed in renal PAR1 expression and plasma creatinine, NGAL or KIM-1 between groups. CONCLUSIONS: Aprotinin did not improve renal perfusion nor reduce renal injury during the first hour following experimental CPB despite preservation of renal endothelial integrity and reduction of renal edema.

The effect of targeting Tie2 on hemorrhagic shock-induced renal perfusion disturbances in rats.

BACKGROUND: Hemorrhagic shock is associated with acute kidney injury and increased mortality. Targeting the endothelial angiopoietin/Tie2 system, which regulates endothelial permeability, previously reduced hemorrhagic shock-induced vascular leakage. We hypothesized that as a consequence of vascular leakage, renal perfusion and function is impaired and that activating Tie2 restores renal perfusion and function. METHODS: Rats underwent 1 h of hemorrhagic shock and were treated with either vasculotide or PBS as control, followed by fluid resuscitation for 4 h. Microcirculatory perfusion was measured in the renal cortex and cremaster muscle using contrast echography and intravital microscopy, respectively. Changes in the angiopoietin/Tie2 system and renal injury markers were measured in plasma and on protein and mRNA level in renal tissue. Renal edema formation was determined by wet/dry weight ratios and renal structure by histological analysis. RESULTS: Hemorrhagic shock significantly decreased renal perfusion (240 ± 138 to 51 ± 40, p < 0.0001) and cremaster perfusion (12 ± 2 to 5 ± 2 perfused vessels, p < 0.0001) compared to baseline values. Fluid resuscitation partially restored both perfusion parameters, but both remained below baseline values (renal perfusion 120 ± 58, p = 0.08, cremaster perfusion 7 ± 2 perfused vessels, p < 0.0001 compared to baseline). Hemorrhagic shock increased circulating angiopoietin-1 (p < 0.0001), angiopoietin-2 (p < 0.0001) and soluble Tie2 (p = 0.05), of which angiopoietin-2 elevation was associated with renal edema formation (r = 0.81, p < 0.0001). Hemorrhagic shock induced renal injury, as assessed by increased levels of plasma neutrophil gelatinase-associated lipocalin (NGAL: p < 0.05), kidney injury marker-1 (KIM-1; p < 0.01) and creatinine (p < 0.05). Vasculotide did not improve renal perfusion (p > 0.9 at all time points) or reduce renal injury (NGAL p = 0.26, KIM-1 p = 0.78, creatinine p > 0.9, renal edema p = 0.08), but temporarily improved cremaster perfusion at 3 h following start of fluid resuscitation compared to untreated rats (resuscitation + 3 h: 11 ± 3 vs 8 ± 3 perfused vessels, p < 0.05). CONCLUSION: Hemorrhagic shock-induced renal impairment cannot be restored by standard fluid resuscitation, nor by activation of Tie2. Future treatment strategies should focus on reducing angiopoietin-2 levels or on activating Tie2 via an alternative strategy.