Sevelamer revisited: pleiotropic effects on endothelial and cardiovascular risk factors in chronic kidney disease and end-stage renal disease

Association between advanced glycation end products and uveitis/scleritis activity in patients with active immune-mediated ocular inflammatory diseases

PURPOSE

To investigate for association between skin autofluorescence (SAF) advanced glycation end products (AGEs) and uveitis/scleritis activity in systemic inflammatory disease-related active non-infectious uveitis/scleritis patients.

METHODS

This cross-sectional study was conducted at Siriraj Hospital during October 2019 to March 2020. AGEs were measured by SAF method in systemic immune-related disease patients with active uveitis/scleritis, and those results were compared with those of healthy age-matched controls.

RESULTS

Thirty-one active non-infectious uveitis/scleritis patients and 31 age-matched controls were enrolled. The mean age of patients was 40.0 ± 12.8 years, and most were female (55.0%). The most common associated systemic immune-related disease was Vogt-Koyanagi-Harada disease (n = 14). Mean SAF AGE level in the study group compared to the control group was 2.38 ± 0.66 arbitrary units (AU) versus 2.58 ± 0.56 AU, respectively (p = 0.20). Multivariate analysis showed decreased SAF AGE level to be significantly associated with active ocular inflammation, (odds ratio: 0.01, 95% confidence interval: 0.00004-0.81; p = 0.04).

CONCLUSIONS

SAF AGE level was not so far found to be a reliable biomarker for indicating uveitis/scleritis activity in systemic immune-related disease patients with active ocular inflammation.

CLINICAL TRIAL REGISTRATION

Thai Clinical Trials Registry, https://www.thaiclinicaltrials.org/ . (Reg. No. TCTR20200114004, registered date 01/01/2020, beginning date of the trial 10/01/2019).

Role of endothelial cells in vascular calcification

Vascular calcification (VC) is active and regulates extraosseous ossification progress, which is an independent predictor of cardiovascular disease (CVD) morbidity and mortality. Endothelial cells (ECs) line the innermost layer of blood vessels and directly respond to changes in flow shear stress and blood composition. Together with vascular smooth muscle cells, ECs maintain vascular homeostasis. Increased evidence shows that ECs have irreplaceable roles in VC due to their high plasticity. Endothelial progenitor cells, oxidative stress, inflammation, autocrine and paracrine functions, mechanotransduction, endothelial-to-mesenchymal transition (EndMT), and other factors prompt ECs to participate in VC. EndMT is a dedifferentiation process by which ECs lose their cell lineage and acquire other cell lineages; this progress coexists in both embryonic development and CVD. EndMT is regulated by several signaling molecules and transcription factors and ultimately mediates VC via osteogenic differentiation. The specific molecular mechanism of EndMT remains unclear. Can EndMT be reversed to treat VC? To address this and other questions, this study reviews the pathogenesis and research progress of VC, expounds the role of ECs in VC, and focuses on the regulatory factors underlying EndMT, with a view to providing new concepts for VC prevention and treatment.

Coagulation and Endothelial Dysfunction Associated with NAFLD: Current Status and Therapeutic Implications

Non-alcoholic fatty liver disease (NAFLD) is closely related to insulin resistance, type 2 diabetes mellitus and obesity. It is considered a multisystem disease and there is a strong association with cardiovascular disease and arterial hypertension, which interfere with changes in the coagulation system. Coagulation disorders are common in patients with hepatic impairment and are dependent on the degree of liver damage. Through a review of the literature, we consider and discuss possible disorders in the coagulation cascade and fibrinolysis, endothelial dysfunction and platelet abnormalities in patients with NAFLD.

Gut microbiome in hemodialysis patients treated with calcium acetate or treated with sucroferric oxyhydroxide: a pilot study

PURPOSE

It has been proved that the gut microbiome is altered in patients with chronic kidney disease. This contributes to chronic inflammation and increases cardiovascular risk and mortality, especially in those undergoing hemodialysis. Phosphate binders may potentially induce changes in their microbiome. This trial aimed to compare the changes in the gut microbiome of hemodialysis patients treated with calcium acetate to those treated with sucroferric oxyhydroxide.

METHODS

Twelve hemodialysis patients were distributed to receive calcium acetate or sucroferric oxyhydroxide for 5 months. Blood samples (for biochemical analysis) and stool samples (for microbiome analysis) were collected at baseline, 4, 12, and 20 weeks after treatment initiation. Fecal DNA was extracted and a 16S rRNA sequencing library was constructed targeting the V3 and V4 hypervariable regions.

RESULTS

Regarding clinical variables and laboratory parameters, no statistically significant differences were observed between calcium acetate or sucroferric oxyhydroxide groups. When analyzing stool samples, we found that all patients were different (p = 0.001) among themselves and these differences were kept along the 20 weeks of treatment. The clustering analysis in microbial profiles grouped the samples of the same patient independently of the treatment followed and the stage of the treatment.

CONCLUSION

These results suggest that a 5-month treatment with either calcium acetate or sucroferric oxyhydroxide did not modify baseline diversity or baseline bacterial composition in hemodialysis patients, also about the high-variability profiles of the gut microbiome found among these patients.

The Influence of Sevelamer Hydrochloride and Calcium Carbonate on Markers of Inflammation and Oxidative Stress in Hemodialysis at Six Months of Follow-Up

Patients with end-stage renal disease (ESRD) present alterations in mineral and bone metabolism. Hyperphosphatemia in ESRD is considered an independent risk factor for cardiovascular disease (CVD), increasing morbidity, and mortality. Sevelamer hydrochloride is a calcium-free, non-absorbable phosphate-chelating polymer. Calcium carbonate chelator is helpful in controlling serum phosphate levels. There is insufficient information on the influence of sevelamer hydrochloride and calcium carbonate on the behavior of oxidative stress (OS) markers and inflammation in patients on hemodialysis (HD). A randomized open clinical trial was carried out on patients to evaluate sevelamer hydrochloride and calcium carbonate influence at 6 months of study follow-up. Levels of oxidants (LPO, NO, and 8-isoprostanes), antioxidants (SOD and TAC), oxidative DNA damage (8-OHdG and hOGG1), pro-inflammatory cytokines (IL-6 and TNF-α), and inflammation markers (ferritin and C-reactive protein) were measured with colorimetric and ELISA methods. We found a significant increase in oxidants LPO and NO, and antioxidants SOD and TAC, and downregulation of IL-6 and TNF-α. Ferritin decrease at 6 months follow-up in the sevelamer hydrochloride group. Increase in C-reactive protein was found in the group of patients treated with calcium carbonate. In conclusion, we found an oxidative state imbalance with increase in LPO and NO oxidants. The activity of the antioxidant enzymes (SOD and TAC) was also found to increase, suggesting a compensatory effect in the face of increase in oxidants. The same phenomenon was observed with increase in the oxidative damage marker to DNA and the increase in the DNA repair enzyme, suggesting a compensatory effect. Pro-inflammatory cytokines were predominantly downregulated by TNF-α in the group that ingested sevelamer hydrochloride in the final determination at 6 months of follow-up. Serum ferritin levels decreased significantly at the end of follow-up in patients on HD in the sevelamer hydrochloride group. The management of hyperphosphatemia with sevelamer hydrochloride appears to have obvious anti-inflammatory and antioxidant benefits.

Systematic review and meta-analysis of potential pleiotropic effects of sevelamer in chronic kidney disease: Beyond phosphate control

Sevelamer, has been shown to have many pleiotropic actions on lipid panel, various inflammatory markers, and blood glucose levels in chronic kidney disease patients. We conducted a systematic review and meta-analysis to compare these pleiotropic effects of sevelamer to other phosphate binders used in chronic kidney disease patients. The relevant randomized controlled trials published from 1 January 2001 to 31 November 2019 on the following databases: Cochrane Central Register of Controlled Trials published in The Cochrane Library, PubMed, Scopus and Google Scholar were identified. All the included studies were independently assessed for eligibility and risk of bias. The modified data extraction form of Cochrane was used. This review included 44 studies for qualitative analysis and 28 reports for quantitative analysis. A meta-analysis of three studies (n = 180) showed that glycated haemoglobin had significantly decreased in sevelamer-treated patients (MD: 0.5%; p = <.001). Compared with calcium-based phosphate binders, sevelamer showed a significant reduction in low-density lipoprotein (MD: -19.43 mg/dL; p = <.001) and total cholesterol (MD: -19.98 mg/dL; p < .001). A significant increase in high-density lipoprotein (MD: 1.29 mg/dL; p = .05) was also prominent in sevelamer treated patients. However, we were not able to observe a significant change in other biochemical parameters such as TG, CRP, hs-CRP, FGF-23, IL-6 and albumin as, no statistically significant difference was observed.

Efficacy and safety of sucroferric oxyhydroxide in the treatment of hyperphosphataemia in chronic kidney disease in Asturias. FOSFASTUR study

Alterations in bone and mineral metabolism are very common in chronic kidney disease (CKD). The increase in phosphate levels leads to bone disease, risk of calcification and greater mortality, so any strategy aimed at reducing them should be welcomed. The latest drug incorporated into the therapeutic arsenal to treat hyperphosphataemia in CKD is Sucroferric Oxyhydroxide (SFO).

OBJECTIVE

To analyse the efficacy and safety of OSF in three cohorts of patients, one with advanced chronic kidney disease not on dialysis (CKD-NoD), another on peritoneal dialysis (PD) and the last on haemodialysis (HD), followed for six months.

METHODS

A prospective, observational, multicentre study in clinical practice. Clinical and epidemiological variables were analysed. The evolution of parameters relating to alterations in bone and mineral metabolism and anaemia was analysed.

RESULTS

Eighty-five patients were included in the study (62 ± 12 years, 64% male, 34% diabetic), 25 with CKD-NoD, 25 on PD and lastly, 35 on HD. In 66 patients (78%), SFO was the first phosphate binder; in the other 19, SFO replaced a previous phosphate binder due to poor tolerance or efficacy. The initial dose of SFO was 964 ± 323 mg/day. Overall, serum phosphate levels saw a significant reduction at three months of treatment (19.6%, P < 0.001). There were no differences in the efficacy of the drug when the different populations analysed were compared. Over the course of the study, there were no changes to levels of calcium, PTHi, ferritin, or the transferrin and haemoglobin saturation indices, although there was a tendency for the last two to increase. Twelve patients (14%) withdrew from follow-up, ten due to gastrointestinal adverse effects (primarily diarrhoea) and two were lost to follow-up (kidney transplant). The mean dose of the drug that the patients received increased over time, up to 1147 ± 371 mg/day.

CONCLUSIONS

SFO is an effective option for the treatment of hyperphosphataemia in patients with CKD both in the advanced phases of the disease and on dialysis. We found similar efficacy across the three groups analysed. The higher their baseline phosphate level, the greater the reduction in the serum levels. A notable reduction in phosphate levels can be achieved with doses of around 1000 mg/day. Diarrhoea was the most common side effect, although it generally was not significant.

Efficacy and safety of sucroferric oxyhydroxide in the treatment of hyperphosphataemia in chronic kidney disease. FOSFASTUR study

INTRODUCTION

Alterations in bone and mineral metabolism are very common in chronic kidney disease (CKD). The increase in phosphate levels leads to bone disease, risk of calcification and greater mortality, so any strategy aimed at reducing them should be welcomed. The latest drug incorporated into the therapeutic arsenal to treat hyperphosphataemia in CKD is sucroferric oxyhydroxide (SFO).

OBJECTIVE

To analyse the efficacy and safety of SFO in 3 cohorts of patients, one with advanced CKD not on dialysis, another on peritoneal dialysis and the last on haemodialysis, followed for 6 months.

METHODS

A prospective, observational, multicentre study in clinical practice. Clinical and epidemiological variables were analysed. The evolution of parameters relating to alterations in bone and mineral metabolism and anaemia was analysed.

RESULTS

Eighty-five patients were included in the study (62±12 years, 64% male, 34% diabetic), 25 with advanced CKD not on dialysis, 25 on peritoneal dialysis and lastly, 35 on haemodialysis. In 66 patients (78%), SFO was the first phosphate binder; in the other 19, SFO replaced a previous phosphate binder due to poor tolerance or efficacy. The initial dose of SFO was 964±323mg/day. Overall, serum phosphate levels saw a significant reduction at 3 months of treatment (19.6%; P<.001). There were no differences in the efficacy of the drug when the different populations analysed were compared. Over the course of the study, there were no changes to levels of calcium, PTHi, ferritin, transferrin saturation index or haemoglobin, although there was a tendency for the last 2 to increase. Twelve patients (14%) withdrew from follow-up, 10 due to gastrointestinal adverse effects (primarily diarrhoea) and 2 were lost to follow-up (kidney transplant). The mean dose of the drug that the patients received increased over time, up to 1,147±371mg/day.

CONCLUSIONS

SFO is an effective option for the treatment of hyperphosphataemia in patients with CKD both in the advanced phases of the disease and on dialysis. We found similar efficacy across the 3 groups analysed. The higher their baseline phosphate level, the greater the reduction in the serum levels. A notable reduction in phosphate levels can be achieved with doses of around 1,000mg/day. Diarrhoea was the most common side effect, although it generally was not significant.

The Novel Phosphate and Bile Acid Sequestrant Polymer SAR442357 Delays Disease Progression in a Rat Model of Diabetic Nephropathy

As a gut-restricted, nonabsorbed therapy, polymeric bile acid sequestrants (BAS) play an important role in managing hyperlipidemia and hyperglycemia. Similarly, nonabsorbable sequestrants of dietary phosphate have been used for the management of hyperphosphatemia in end-stage renal disease. To evaluate the potential utility of such polymer sequestrants to treat type 2 diabetes (T2D) and its associated renal and cardiovascular complications, we synthesized a novel polymeric sequestrant, SAR442357, possessing optimized bile acid (BA) and phosphate sequestration characteristics. Long-term treatment of T2D obese ^cZucker fatty/Spontaneously hypertensive heart failure F1 hybrid (ZSF1) with SAR442357 resulted in enhanced sequestration of BAs and phosphate in the gut, improved glycemic control, lowering of serum cholesterol, and attenuation of diabetic kidney disease (DKD) progression. In comparison, colesevelam, a BAS with poor phosphate binding properties, did not prevent DKD progression, whereas losartan, an angiotensin II receptor blocker that is widely used to treat DKD, showed no effect on hyperglycemia. Analysis of hepatic gene expression levels of the animals treated with SAR442357 revealed upregulation of genes responsible for the biosynthesis of cholesterol and BAs, providing clear evidence of target engagement and mode of action of the new sequestrant. Additional hepatic gene expression pathway changes were indicative of an interruption of the enterohepatic BA cycle. Histopathological analysis of ZSF1 rat kidneys treated with SAR442357 further supported its nephroprotective properties. Collectively, these findings reveal the pharmacological benefit of simultaneous sequestration of BAs and phosphate in treating T2D and its associated comorbidities and cardiovascular complications. SIGNIFICANCE STATEMENT: A new nonabsorbed polymeric sequestrant with optimum phosphate and bile salt sequestration properties was developed as a treatment option for DKD. The new polymeric sequestrant offered combined pharmacological benefits including glucose regulation, lipid lowering, and attenuation of DKD progression in a single therapeutic agent.

Management of Hyperphosphatemia in End-Stage Renal Disease: A New Paradigm

Bone and mineral metabolism becomes dysregulated with progression of chronic kidney disease (CKD), and increasing levels of parathyroid hormone serve as an adaptive response to maintain normal phosphorus and calcium levels. In end-stage renal disease, this response becomes maladaptive and high levels of phosphorus may occur. We summarize strategies to control hyperphosphatemia based on a systematic literature review of clinical trial and real-world observational data on phosphorus control in hemodialysis patients with CKD-mineral bone disorder (CKD-MBD). These studies suggest that current management options (diet and lifestyle changes; regular dialysis treatment; and use of phosphate binders, vitamin D, calcimimetics) have their own benefits and limitations with variable clinical outcomes. A more integrated approach to phosphorus control in dialysis patients may be necessary, incorporating measurement of multiple biomarkers of CKD-MBD pathophysiology (calcium, phosphorus, and parathyroid hormone) and correlation between diet adjustments and CKD-MBD drugs, which may facilitate improved patient management.

Effects of Sevelamer Carbonate in Patients With CKD and Proteinuria: The ANSWER Randomized Trial

RATIONALE & OBJECTIVE

Hyperphosphatemia is associated with increased risk for chronic kidney disease (CKD) progression and reduced antiproteinuric effects of renin-angiotensin system (RAS) blockers. We investigated whether the phosphate binder sevelamer carbonate may enhance the antiproteinuric effect of RAS inhibitors in patients with CKD.

STUDY DESIGN

Phase 2, randomized, controlled, open-label, crossover trial.

SETTING & PARTICIPANTS

Between November 2013 and December 2014, we enrolled 53 patients with CKD with estimated glomerular filtration rates (eGFRs)>15mL/min/1.73m² and residual proteinuria with protein excretion≥0.5g/24h despite maximal tolerated ramipril and/or irbesartan therapy from 2 nephrology units in Italy.

INTERVENTION

After stratification by serum phosphate level, ≤4 or>4mg/dL, patients were randomly assigned to 3 months of sevelamer (1,600mg thrice daily) treatment followed by 3 months without sevelamer separated by a 1-month washout period or 3 months without sevelamer followed by 3 months with sevelamer, also separated by a 1-month washout period.

OUTCOMES

The primary outcome was 24-hour proteinuria (n=49patients). Secondary outcomes included measured GFR (using iohexol plasma clearance), office blood pressure (BP), serum lipid levels, levels of inflammation and bone metabolism biomarkers, urinary electrolyte levels, and arterial stiffness.

RESULTS

Changes in proteinuria during the 3-month treatment with (from 1.36 [IQR, 0.77-2.51] to 1.36 [IQR, 0.77-2.60] g/24h) or without (from 1.36 [IQR, 0.99-2.38] to 1.48 [IQR, 0.81-2.77] g/24h) sevelamer were similar (P=0.1). Sevelamer reduced urinary phosphate excretion without affecting serum phosphate levels. Sevelamer reduced C-reactive protein (CRP), glycated hemoglobin, and total and low-density lipoprotein cholesterol levels and increased high-density lipoprotein cholesterol levels without affecting levels of office BP, measured GFR, fibroblast growth factor 23, klotho, intact parathyroid hormone, serum vitamin D, or other urinary electrolytes. Results were similar in the low- and high-phosphate groups. Sevelamer was well tolerated. Adverse events were comparable between treatment periods. One case of transient hypophosphatemia was observed during treatment with sevelamer.

LIMITATIONS

Short treatment duration, lower pretreatment proteinuria than expected.

CONCLUSIONS

3-month sevelamer treatment did not reduce proteinuria in patients with CKD on maximal RAS blockade. Amelioration of inflammation and dyslipidemia with sevelamer treatment raises the possibility that it may confer benefit in patients with CKD beyond reduction of proteinuria.

FUNDING

Sanofi (Milan, Italy).

TRIAL REGISTRATION

Registered at ClinicalTrials.gov with study number NCT01968759.

Comparison of Solute Clearance, Hospitalization Rate, and Aortic Arch Calcification between Online Hemodiafiltration and High-Flux Hemodialysis: A 6-Year Observational Study

BACKGROUND/AIMS

Studies on the long-term clinical benefits of hemodiafiltration (HDF) and high-flux hemodialysis (HFHD) are very limited. This study aimed to investigate the hospitalization rate and aortic arch calcification (AAC) of these two dialysis modalities over 6 years.

METHODS

Participants who received regular HDF and HFHD in one hospital-facilitated hemodialysis center were prospectively enrolled after matching for age, sex, and diabetes between January 2009 and December 2014. Medical records were reviewed retrospectively on demographics, laboratory variables, calcified scores in aortic arch measured by chest radiography, and rates of hospital admission. Cox proportional hazard regression and linear regression were used to obtain the outcome results.

RESULTS

The HDF and HFHD groups consisted of 108 and 102 participants, respectively. Levels of laboratory variables including small soluble solutes and Kt/V were not statistically different over the 6-year period between the HDF and HFHD groups. Calcified scores of the aortic arch increased over 6 years in both groups. The changes in the mean calcified scores were significant when compared between the two groups (0.44-1.82 in HFHD, 0.79-1.8 in HDF, respectively, p = 0.008). Hospitalization rates were 735 per 1,000 patients in the HDF group and 852 per 1,000 patients in the HFHD group, respectively. No significant difference was observed in frequency and days of hospitalization between HDF and HFHD.

CONCLUSION

Hospitalization rates and AAC were observed to be equal for HDF and HFHD.

Malnutrition and cardiovascular risk in haemodialysis patients with chronic kidney disease

ABSTRACT Objective To verify the association between nutritional status and traditional and non-traditional cardiovascular risk factors in haemodialysis patients. Methods A cross-sectional study with 132 patients over 18 years of age on haemodialysis to evaluate nutritional status through Subjective Global Assessment. Information on traditional and non-traditional cardiovascular disease risk factors were obtained using a structured questionnaire; the Framingham score was also used to assess cardiovascular risk. Data analysis was performed using the Chi-square Test or Fischer Exact Test and a Log-binomial Regression Model. Results Malnutrition affected 31.1% of patients. Among them, a higher percentage of smokers (p=0.016), former smokers (p=0.034) and diabetes Mellitus patients (p=0.001) were detected. Malnutrition was found to be 4.53 times more prevalent in diabetic individuals (95%CI: 1.99-10.27) and 2.26 times more prevalent among former smokers (95%CI: 1.04-4.95). Malnourished individuals exhibited a 4.03 times prevalence of moderate to severe cardiovascular risk. Conclusion A high prevalence of malnutrition and of other risk factors for cardiovascular disease were observed. Such factors included diabetes Mellitus, smoking and former smoker conditions and were associated with malnutrition. Inaddition, it was found that malnourished individuals were more likely to develop cardiovascular disease within 10 years.

Gut microbiota, hypertension and chronic kidney disease: Recent advances

A large number of different microbial species populates intestine. Extensive research has studied the entire microbial population and their genes (microbiome) by using metagenomics, metatranscriptomics and metabolomic analysis. Studies suggest that the imbalances of the microbial community causes alterations in the intestinal homeostasis, leading to repercussions on other systems: metabolic, nervous, cardiovascular, immune. These studies have also shown that alterations in the structure and function of the gut microbiota play a key role in the pathogenesis and complications of Hypertension (HTN) and Chronic Kidney Disease (CKD). Increased blood pressure (BP) and CKD are two leading risk factors for cardiovascular disease and their treatment represents a challenge for the clinicians. In this Review, we discuss mechanisms whereby gut microbiota (GM) and its metabolites act on downstream cellular targets to contribute to the pathogenesis of HTN and CKD, and potential therapeutic implications.

Hyperphosphatemia induces senescence in human endothelial cells by increasing endothelin-1 production

Hyperphosphatemia is related to some pathologies, affecting vascular cell behavior. This work analyzes whether high concentration of extracellular phosphate induces endothelial senescence through up‐regulation of endothelin‐1 (ET‐1), exploring the mechanisms involved. The phosphate donor β‐glycerophosphate (BGP) in human endothelial cells increased ET‐1 production, endothelin‐converting enzyme‐1 (ECE‐1) protein, and mRNA expression, which depend on the AP‐1 activation through ROS production. In parallel, BGP also induced endothelial senescence by increasing p16 expression and the senescence‐associated β‐galactosidase (SA‐ß‐GAL) activity. ET‐1 itself was able to induce endothelial senescence, increasing p16 expression and SA‐ß‐GAL activity. In addition, senescence induced by BGP was blocked when different ET‐1 system antagonists were used. BGP increased ROS production at short times, and the presence of antioxidants prevented the effect of BGP on AP1 activation, ECE‐1 expression, and endothelial senescence. These findings were confirmed in vivo with two animal models in which phosphate serum levels were increased: seven/eight nephrectomized rats as chronic kidney disease models fed on a high phosphate diet and aged mice. Both models showed hyperphosphatemia, higher levels of ET‐1, and up‐regulation in aortic ECE‐1, suggesting a direct relationship between hyperphosphatemia and ET‐1. Present results point to a new and relevant role of hyperphosphatemia on the regulation of ET‐1 system and senescence induction at endothelial level, both in endothelial cells and aorta from two animal models. The mechanism involved showed a higher ROS production, which probably activates AP‐1 transcription factor and, as a result, ECE‐1 expression, increasing ET‐1 synthesis, which in consequence induces endothelial senescence.

Activation of the Nrf2-ARE Signaling Pathway Prevents Hyperphosphatemia-Induced Vascular Calcification by Inducing Autophagy in Renal Vascular Smooth Muscle Cells

This study investigates the effect of nuclear factor erythroid 2-related factor 2-antioxidant response element (Nrf2-ARE) signaling pathway in vascular calcification (VC) via inducing Autophagy in renal vascular smooth muscle cells (VSMCs). VSMCs were assigned into six experimental groups: the normal control, high phosphorus, si-negative control (si-NC), Nrf2-siRNA, over-expressed Nrf2, and negative control (NC) groups. RT-PCR was applied to detect the mRNA expressions of the desired Nrf2-ARE signaling pathway-related genes (Nrf2, NQO-1, HO-1, γ-GCS). The protein products of these genes: apoptosis-related genes (LC3I and LC3II), osteogenic marker proetins (Runt-related transcription factor 2) Runx2 and BMP2 were all detected by Western blotting. Autophagosomes in VSMCs were observed under a transmission electron microscope. We discovered an increased calcium ion concentration and upregulated Runx2, BMP2, Nrf2, HO-1, γ-GCS, NQO-1, and LC3II/LC3I expressions in the high phosphorous, si-NC and Nrf2-siRNA, and NC groups, compared with the normal control group. Compared to the high phosphorus and si-NC groups, higher levels of Runx2 and BMP2 but decreased Nrf2, HO-1, γ-GCS, NQO-1, and LC3II/LC3I expressions were detected in the Nrf2-siRNA group. The high phosphorus, si-NC and over-expressed Nrf2 experimental groups all had increased Nrf2, NQO-1, HO-1, γ-GCS, and LC3II/LC3I expressions as well as high numbers of autophagosomes compared with the normal control group. Finally, we detected a lower amount of autophagosomes presence and Nrf2, NQO-1, HO-1 γ-GCS, and LC3II/LC3 protein expression of Nrf2-siRNA group than that of the high phosphorus and si-NC groups. Activation of Nrf2-ARE signaling pathway may prevent hyperphosphatemia-induced VC by inducing autophagy in VSMCs. J. Cell. Biochem. 118: 4708-4715, 2017. © 2017 Wiley Periodicals, Inc.

Predictive Factors of One-Year Mortality in a Cohort of Patients Undergoing Urgent-Start Hemodialysis

Background

Chronic kidney disease (CKD) affects 10–15% of adult population worldwide. Incident patients on hemodialysis, mainly those on urgent-start dialysis at the emergency room, have a high mortality risk, which may reflect the absence of nephrology care. A lack of data exists regarding the influence of baseline factors on the mortality of these patients. The aim of this study was to evaluate the clinical and laboratory characteristics of this population and identify risk factors that contribute to their mortality.

Patients and methods

We studied 424 patients who were admitted to our service between 01/2006 and 12/2012 and were followed for 1 year. We analyzed vascular access, risk factors linked to cardiovascular disease (CVD) and mineral and bone disease associated with CKD (CKD-MBD), and clinical events that occurred during the follow-up period. Factors that influenced patient survival were evaluated by Cox regression analysis.

Results

The patient mean age was 50 ± 18 years, and 58.7% of them were male. Hypertension was the main cause of primary CKD (31.8%). Major risk factors were smoking (19.6%), dyslipidemia (48.8%), and CVD (41%). Upon admission, most patients had no vascular access for hemodialysis (89.4%). Biochemical results showed that most patients were anemic with high C-reactive protein levels, hypocalcemia, hyperphosphatemia, elevated parathyroid hormone and decreased 25-hydroxy vitamin D. At the end of one year, 60 patients died (14.1%). These patients were significantly older, had a lower percentage of arteriovenous fistula in one year, and low levels of 25-hydroxy vitamin D.

Conclusions

The combined evaluation of clinical and biochemical parameters and risk factors revealed that the mortality in urgent-start dialysis is associated with older age and low levels of vitamin D deficiency. A lack of a permanent hemodialysis access after one year was also a risk factor for mortality in this population.

Sevelamer Improves Steatohepatitis, Inhibits Liver and Intestinal Farnesoid X Receptor (FXR), and Reverses Innate Immune Dysregulation in a Mouse Model of Non-alcoholic Fatty Liver Disease

Bile acid sequestrants are synthetic polymers that bind bile acids in the gut and are used to treat dyslipidemia and hyperphosphatemia. Recently, these agents have been reported to lower blood glucose and increase insulin sensitivity by altering bile acid signaling pathways. In this study, we assessed the efficacy of sevelamer in treating mice with non-alcoholic fatty liver disease (NAFLD). We also analyzed how sevelamer alters inflammation and bile acid signaling in NAFLD livers. Mice were fed a low-fat or Western diet for 12 weeks followed by a diet-plus-sevelamer regimen for 2 or 12 weeks. At the end of treatment, disease severity was assessed, hepatic leukocyte populations were examined, and expression of genes involved in farnesoid X receptor (FXR) signaling in the liver and intestine was analyzed. Sevelamer treatment significantly reduced liver steatosis and lobular inflammation. Sevelamer-treated NAFLD livers had notably fewer pro-inflammatory infiltrating macrophages and a significantly greater fraction of alternatively activated Kupffer cells compared with controls. Expression of genes involved in FXR signaling in the liver and intestine was significantly altered in mice with NAFLD as well as in those treated with sevelamer. In a mouse model of NAFLD, sevelamer improved disease and counteracted innate immune cell dysregulation in the liver. This study also revealed a dysregulation of FXR signaling in the liver and intestine of NAFLD mice that was counteracted by sevelamer treatment.

Vascular calcification: When should we interfere in chronic kidney disease patients and how?

Chronic kidney disease (CKD) patients are endangered with the highest mortality rate compared to other chronic diseases. Cardiovascular events account for up to 60% of the fatalities. Cardiovascular calcifications affect most of the CKD patients. Most of this calcification is related to disturbed renal phosphate handling. Fibroblast growth factor 23 and klotho deficiency were incriminated in the pathogenesis of vascular calcification through different mechanisms including their effects on endothelium and arterial wall smooth muscle cells. In addition, deficient klotho gene expression, a constant feature of CKD, promotes vascular pathology and shares in progression of the CKD. The role of gut in the etio-pathogenesis of systemic inflammation and vascular calcification is a newly discovered mechanism. This review will cover the medical history, prevalence, pathogenesis, clinical relevance, different tools used to diagnose, the ideal timing to prevent or to withhold the progression of vascular calcification and the different medications and medical procedures that can help to prolong the survival of CKD patients.

Stop chronic kidney disease progression: Time is approaching

Progression of chronic kidney disease (CKD) is inevitable. However, the last decade has witnessed tremendous achievements in this field. Today we are optimistic; the dream of withholding this progression is about to be realistic. The recent discoveries in the field of CKD management involved most of the individual diseases leading the patients to end-stage renal disease. Most of these advances involved patients suffering diabetic kidney disease, chronic glomerulonephritis, polycystic kidney disease, renal amyloidosis and chronic tubulointerstitial disease. The chronic systemic inflammatory status and increased oxidative stress were also investigated. This inflammatory status influences the anti-senescence Klotho gene expression. The role of Klotho in CKD progression together with its therapeutic value are explored. The role of gut as a major source of inflammation, the pathogenesis of intestinal mucosal barrier damage, the role of intestinal alkaline phosphatase and the dietary and therapeutic implications add a novel therapeutic tool to delay CKD progression.

Sevelamer carbonate reduces the risk of hypomagnesemia in hemodialysis-requiring end-stage renal disease patients

BACKGROUND

Sevelamer has been associated with less progression of vascular calcifications. This effect could be due to a reduction in serum phosphate levels but also to other additive effects. Magnesium has been also shown to prevent vascular calcification but the effect of sevelamer on serum magnesium levels has not been thoroughly evaluated. Our aim was to analyze whether the use of sevelamer reduces the risk of hypomagnesemia in hemodialysis (HD)-requiring end-stage renal disease patients.

METHODS

All prevalent patients from the dialysis unit of the Hospital Italiano de Buenos Aires as of 1 June 2015 were evaluated. They were on three times per week bicarbonate/citrate-buffered HD. They were not receiving phosphate binders or magnesium-containing drugs. The average of three successive monthly magnesium serum levels was considered as the baseline magnesium concentration. Sevelamer carbonate use was retrieved from the patient's clinical records.

RESULTS

One hundred and fifty-one patients were included. A large proportion of individuals were on proton pump inhibitors (PPIs) (66%) and more than 50% were using sevelamer carbonate. Serum magnesium levels were significantly higher in those receiving sevelamer compared with those who did not (2.05 ± 0.3 versus 1.8 ± 0.4 mg/dL; P < 0.05). A larger proportion of individuals receiving sevelamer were among those with normal serum magnesium (P = 0.02), while among those with hypomagnesemia, a larger proportion were on PPIs. In the multivariate model including the use of PPIs, sevelamer carbonate resulted in an independent protective factor for hypomagnesemia (odds ratio: 0.44; 95% confidence interval: 0.21-0.87).

CONCLUSIONS

Hemodialysis patients receiving sevelamer show higher serum magnesium levels and a reduced risk of hypomagnesemia. This effect remains even after adjustment for PPI use. This effect could contribute to the still controversial superiority of sevelamer in preventing vascular calcifications.

Factors associated with serum fetuin-A concentrations after long-term use of different phosphate binders in hemodialysis patients

Background

Fetuin-A is known as a circulating inhibitor of vascular calcification. Factors associated with serum fetuin-A concentrations after long-term use of different phosphate binders in hemodialysis patients is still uncertain.

Methods

In the post-hoc study, we analyzed serum fetuin-A and biochemical factors (Ca, P, i-PTH, hsCRP, TG, LDL-C) in 50 hemodialysis patients, who completed a 48-week, open-Label, controlled randomized parallel-group study. 23 patients received sevelamer and 27 patients received calcium carbonate.

Results

After the 48-week treatment, the sevelamer group had less serum calcium increment, less iPTH decrement, more ALK-P increment, more hsCRP decrement and more LDL-C decrement. There was no significant difference in the serum fetuin-A decrement between two groups. Decreased serum fetuin-A levels were found after 48-week treatment in both groups: from 210.61 (104.73) to 153.85 (38.64) ug/dl, P = 0.003 in sevelamer group, from 203.95 (107.87) to 170.90 (58.02) ug/mL, P =0.002 in calcium group. The decrement in serum fetuin-A (Δfetuin-A) levels was associated with ΔCa (ρ = - 0.230, P = 0.040), ΔiPTH (ρ = 0.306, P = 0.031) and Δalbumin (ρ = 0.408, P = 0.003), not associated with sevelamer use, ΔP and ΔhsCRP.

Conclusion

After long-term sevelamer or calcium carbonate treatment, both groups of maintenance HD patients had lower serum fetuin-A levels. Serum levels of increased calcium, decreased iPTH and decreased albumin were associated with the serum fetuin-A decrement.

Sevelamer crystals in the mucosa of the gastrointestinal tract in a teenager with end-stage renal disease

BACKGROUND

Non-calcium-containing phosphate binders, such as sevelamer preparations, are being increasingly used in patients on dialysis due to their lower association with hypercalcemia and cardiovascular morbidity and mortality. While minor gastrointestinal side effects are quite common with the use of sevelamer, more serious gastrointestinal toxicities have only rarely been reported.

CASE-DIAGNOSIS/TREATMENT

We report a pediatric patient on maintenance dialysis receiving sevelamer hydrochloride who developed severe abdominal pain and a high-grade stricture of the sigmoid colon. The patient underwent exploratory laparotomy, resulting in a partial colectomy and colostomy. Histopathologic examination showed colonic mucosal injury and characteristic "fish-scale"-like sevelamer hydrochloride crystals within the mucosa.

CONCLUSIONS

Whether the sevelamer crystals were causal, contributory or purely incidental remains to be clearly elucidated. However, our case raises sufficient concern to warrant additional investigation into whether there is a causal relationship between sevelamer use and intestinal mucosal injury.

Cost Effectiveness of Sucroferric Oxyhydroxide Compared with Sevelamer Carbonate in the Treatment of Hyperphosphataemia in Patients Receiving Dialysis, from the Perspective of the National Health Service in Scotland

BACKGROUND

Hyperphosphataemia is common and harmful in patients receiving dialysis. Treatment options include noncalcium-based phosphate binders such as sevelamer carbonate (SC) and sucroferric oxyhydroxide (PA21).

OBJECTIVE

The aim of this study was to determine the health economic impact of PA21-based strategies compared with SC-based strategies, from the perspective of the Scottish National Health Service (NHS).

METHODS

A Markov model was constructed based on data from a randomised clinical trial comparing PA21 and SC. Model input parameters were derived from published literature, national statistics and unpublished sources. Costs (price year 2012) and effects were discounted at 3.5 %. Analysis with a lifelong time horizon yielded the incremental cost-effectiveness ratio (ICER), expressed as cost or savings per quality-adjusted life-year (QALY) gained or forgone. Deterministic and probabilistic sensitivity analysis was performed to explore uncertainties around assumptions and model input parameters.

RESULTS

In the base-case analysis, phosphorus reductions for PA21 and SC were 1.93 and 1.95 mg/dL. Average undiscounted survival was estimated to be 7.61 years per patient in both strategies. PA21 patients accrued less QALYs (2.826) than SC patients (2.835), partially due to differential occurrence of side effects. Total costs were ₤ 13,119 and ₤ 14,728 for PA21 and SC, respectively (difference per patient of ₤ 1609). By using PA21 versus SC, one would save ₤ 174,999 (or ₤ 123,463 when including dialysis and transplantation costs) for one QALY forgone. A scenario modelling the nonsignificant reduction in mortality (relative risk 0.714) observed in the trial yielded an ICER for PA21 of ₤ 22,621 per QALY gained. In probabilistic sensitivity analysis of the base-case, PA21 was dominant in 11 %, and at least cost-effective in 53 %, of iterations, using a threshold of ₤ 20,000 per QALY gained.

CONCLUSIONS

The use of PA21 versus SC in hyperphosphataemic patients being intolerant of calcium-based phosphate binders may be cost saving and yields only very limited disadvantages in terms of quality-adjusted survival. PA21 appears to be cost-effective from the perspective of the Scottish NHS.

Iron-based phosphate binders--a new element in management of hyperphosphatemia

INTRODUCTION

Management of serum phosphorus in patients with chronic kidney disease remains a significant clinical challenge. A pivotal component of the clinical approach to maintaining serum phosphorus concentrations towards the normal range is the use of phosphate binding agents in addition to comprehensive dietary counseling. The available agents work similarly by capitalizing on a cation within the agent to bind negatively charged phosphorus, forming an insoluble complex and reducing ingested phosphorus absorption. Despite several effective options for phosphate binder therapies, patient adherence remains an issue, mainly due to adverse effect profiles and large daily pill burdens.

AREAS COVERED

Two new iron-based phosphate binder therapies have recently become available in the United States, sucroferric oxyhydroxide and ferric citrate. These agents have both been shown to effectively reduce serum phosphorus comparably to widely used calcium-based binders and sevelamer salts.

EXPERT OPINION

The two new iron-based binders differ substantially with regard to phosphate binding chemistry and iron absorption profiles. Their place in therapy is still evolving and the impact of pill burden, gastrointestinal adverse effect profiles, potential cost reduction of anemia therapies and physiologic effects of long-term iron exposure need to be further evaluated.

Effect of diet-derived advanced glycation end products on inflammation

Advanced glycation end products (AGEs) formed via the Maillard reaction during the thermal processing of food contributes to the flavor, color, and aroma of food. A proportion of food-derived AGEs and their precursors is intestinally absorbed and accumulates within cells and tissues. AGEs have been implicated in the pathogenesis of diabetes-related complications and several chronic diseases via interaction with the receptor for AGEs, which promotes the transcription of genes that control inflammation. The dicarbonyls, highly reactive intermediates of AGE formation, are also generated during food processing and may incite inflammatory responses through 1) the suppression of protective pathways, 2) the incretin axis, 3) the modulation of immune-mediated signaling, and 4) changes in gut microbiota profile and metabolite sensors. In animal models, restriction of dietary AGEs attenuates chronic low-grade inflammation, but current evidence from human studies is less clear. Here, the emerging relationship between excess dietary AGE consumption and inflammation is explored, the utility of dietary AGE restriction as a therapeutic strategy for the attenuation of chronic diseases is discussed, and possible avenues for future investigation are suggested.

A Study to Inform the Design of a National Multicentre Randomised Controlled Trial to Evaluate If Reducing Serum Phosphate to Normal Levels Improves Clinical Outcomes including Mortality, Cardiovascular Events, Bone Pain, or Fracture in Patients on Dialysis

Background. Retrospective, observational studies link high phosphate with mortality in dialysis patients. This generates research hypotheses but does not establish “cause-and-effect.” A large randomised controlled trial (RCT) of about 3000 patients randomised 50 : 50 to lower or higher phosphate ranges is required to answer the key question: does reducing phosphate levels improve clinical outcomes? Whether such a trial is technically possible is unknown; therefore, a study is necessary to inform the design and conduct of a future, definitive trial. Methodology. Dual centre prospective parallel group study: 100 dialysis patients randomized to lower (phosphate target 0.8 to 1.4 mmol/L) or higher range group (1.8 to 2.4 mmol/L). Non-calcium-containing phosphate binders and questionnaires will be used to achieve target phosphate. Primary endpoint: percentage successfully titrated to required range and percentage maintained in these groups over the maintenance period. Secondary endpoints: consent rate, drop-out rates, and cardiovascular events. Discussion. This study will inform design of a large definitive trial of the effect of phosphate on mortality and cardiovascular events in dialysis patients. If phosphate lowering improves outcomes, we would be reassured of the validity of this clinical practice. If, on the other hand, there is no improvement, a reassessment of resource allocation to therapies proven to improve outcomes will result. Trial Registration Number. This trial is registered with ISRCTN registration number ISRCTN24741445.

Novel Therapeutic Options for the Treatment of Mineral Metabolism Abnormalities in End Stage Renal Disease

Abnormalities in mineral metabolism are a universal complication in dialysis patients and are associated with an increased risk of cardiovascular disease and mortality. Hyperphosphatemia, increased fibroblast growth factor 23 levels and secondary hyperparathyroidism are all strongly associated with adverse outcomes in end stage renal disease (ESRD) and most treatment strategies target these parameters. Over the past few years, new therapies have emerged for the treatment of abnormalities of mineral metabolism in ESRD and many are promising. This article will review these new therapeutic options including the potential advantages and disadvantages compared to existing therapies.

Use of sevelamer in chronic kidney disease: beyond phosphorus control

Sevelamer is a non-calcium phosphate binder used in advanced chronic kidney disease (CKD) and in dialysis for hyperphosphataemia control. Several experimental, observational studies and clinical trials have shown that sevelamer has pleiotropic effects, beyond hyperphosphataemia control, including actions on inflammation, oxidative stress, lipid profile and atherogenesis, vascular calcification, endothelial dysfunction and the reduction of several uremic toxins. This is the biological basis for its global effect on cardiovascular morbidity and mortality in patients with chronic kidney disease. This review focuses on these pleiotropic actions of sevelamer and their impact on cardiovascular health, with the experience published after more than ten years of clinical expertise.

Sevelamer carbonate: a review in hyperphosphataemia in adults with chronic kidney disease

Sevelamer carbonate (Renvela(®)), a buffered form of sevelamer hydrochloride (Renagel(®)), is an orally administered non-absorbed phosphate-binding anion exchange resin used in the treatment of hyperphosphataemia in chronic kidney disease (CKD). In the EU, sevelamer carbonate is approved in adult CKD patients who require dialysis and in those who do not require dialysis with serum phosphate levels ≥ 1.78 mmol/L, whereas in the USA sevelamer carbonate is approved in adult CKD patients who require dialysis. Sevelamer carbonate and sevelamer hydrochloride achieved similar reductions in serum phosphate levels in randomized comparative trials in patients with CKD receiving haemodialysis; sevelamer carbonate also reduced serum phosphate levels in noncomparative studies in CKD patients not requiring dialysis. The most common adverse events with sevelamer carbonate are gastrointestinal in nature. Sevelamer has pleiotropic effects, such as improving the serum lipid profile and attenuating endothelial and cardiovascular risk factors in CKD. All formulations of sevelamer have markedly higher acquisition costs than calcium-based phosphate binders. Cost-effectiveness analyses focusing specifically on sevelamer carbonate have not been conducted, and those based on clinical trial data with sevelamer hydrochloride have provided both favourable and unfavourable results compared with calcium-based phosphate binders, reflecting heterogeneity between modelled analyses in terms of data sources, assumptions, comparators, geographical regions, type of costs included and other factors. Although well-designed studies evaluating the impact of phosphate binders on hard clinical endpoints appear to be warranted, sevelamer carbonate may be particularly useful for the treatment of patients at risk of metabolic acidosis (offering advantages over sevelamer hydrochloride in this regard) and for individuals requiring treatment with a phosphate binding agent that does not contain aluminium or calcium.

Cardiovascular mortality in chronic kidney disease patients: potential mechanisms and possibilities of inhibition by resin-based phosphate binders

Cardiovascular mortality has been considered as the most important risk associated with chronic kidney disease. The mechanisms underlying this include inflammation, poor control of serum phosphate, high serum calcium, increased calcification of the arteries and cardiac valves, hyperlipidemia, diabetes, severe anemia, uric acid accumulation and others. Elevated phosphate levels have been strongly associated with increased mortality, thus phosphate-binding drugs have long been used to control the increase serum phosphate levels. However, phosphate-binding drugs differ considerably and recently numerous publications suggest differences between agents in the effects on overall mortality. The resin-based phosphate binders, comprising sevelamer and colestilan, not only reduce serum phosphate but also do not raise serum calcium. In addition, they reduce serum LDL-C, inflammation, uric acid and high Hba1c values. These differences suggest that not all phosphate binders may be equal in the context of cardiovascular mortality in this patient population.

Sevelamer in a diabetologist's perspective: a phosphate-binding resin with glucose-lowering potential

Sevelamer is a calcium-free and metal-free phosphate-binding oral drug used in the management of hyperphosphataemia in chronic kidney disease. Preclinical and clinical trials have shown glucose and lipid-lowering effects of sevelamer, thereby giving rise to a potential role of the drug in the treatment of patients with type 2 diabetes. These 'novel' effects are most probably derived from the bile acid-binding properties of sevelamer. The proposed potential is supported by the approval of the bile acid sequestrant colesevelam in the United States for the treatment of type 2 diabetes and hypercholesterolaemia. This article offers a brief review on the effects of sevelamer and a perspective on the potential mechanisms behind the glucose-lowering effect of the drug.

Phosphate balance in ESRD: diet, dialysis and binders against the low evident masked pool

Phosphate metabolism is crucial in the pathophysiology of secondary hyperparathyroidism and vascular calcification. High phosphate levels have been consistently associated with unfavorable outcomes in dialysis patients, but several limitations are still hampering a resolutive definition of the optimal targets of phosphate serum levels to be achieved in this cohort. Nonetheless, hyperphosphatemia is a late marker of phosphate overload in humans. Clinical nephrologists routinely counteract the positive phosphate balance in dialysis patients through nutritional counseling, stronger phosphate removal by dialysis and prescription of phosphate binders. However, the superiority against placebo of phosphate control by diet, dialysis or binders in terms of survival has never been tested in dedicated randomized controlled trials. The present review discusses this conundrum with particular emphasis on the rationale supporting the value of a simultaneous intervention against phosphate overload in dialysis patients via the improvement of dietary intakes, dialysis efficiency and an individualized choice of phosphate binders.