Chronic renal failure: a cardiovascular risk factor

Ticagrelor or Clopidogrel as Antiplatelet Agents in Patients with Chronic Kidney Disease and Cardiovascular Disease: A Meta-analysis

INTRODUCTION

The worldwide prevalence of chronic kidney disease (CKD) has significantly increased in the past decades. Scientific reports have shown CKD to be an enhancing risk factor for the development of cardiovascular disease (CVD), which is the leading cause of premature death in patients with CKD. Clinical practice guidelines are ambiguous in view of the use of antiplatelet drugs in patients with CKD because patients with moderate-to-severe CKD were often excluded from clinical trials evaluating the efficacy and safety of anticoagulants and antiplatelet agents. In this analysis, we aimed to systematically assess the adverse cardiovascular and bleeding outcomes that were observed with ticagrelor versus clopidogrel use in patients with CKD and cardiovascular disease.

METHODS

Electronic databases including Web of Science, Google Scholar, http://www.

CLINICALTRIALS

gov , Cochrane database, EMBASE, and MEDLINE were carefully searched for English-based articles comparing ticagrelor with clopidogrel in patients with CKD. Adverse cardiovascular outcomes and bleeding events were the endpoints in this study. The latest version of the RevMan software (version 5.4) was used to analyze the data. Risk ratios (RR) with 95% confidence intervals (CI) were used to represent the data post analysis.

RESULTS

A total of 15,664 participants were included in this analysis, whereby 2456 CKD participants were assigned to ticagrelor and 13,208 CKD participants were assigned to clopidogrel. Our current analysis showed that major adverse cardiac events (MACEs) (RR: 0.85, 95% CI: 0.71-1.03; P = 0.09), all-cause mortality (RR: 0.82, 95% CI: 0.57- 1.18; P = 0.29), cardiovascular death (RR: 0.83, 95% CI: 0.56-1.23; P = 0.35), myocardial infarction (RR: 0.87, 95% CI: 0.70-1.07; P = 0.19), ischemic stroke (RR: 0.80, 95% CI: 0.58-1.11; P = 0.18), and hemorrhagic stroke (RR: 1.06, 95% CI: 0.38-2.99; P = 0.91) were not significantly different in CKD patients who were treated with ticagrelor versus clopidogrel. Thrombolysis in myocardial infarction (TIMI)-defined minor (RR: 0.89, 95% CI: 0.52-1.53; P = 0.68) and TIMI major bleeding (RR: 1.10, 95% CI: 0.69-1.76; P = 0.67) were also not significantly different. However, bleeding defined according to the academic research consortium (BARC) bleeding type 1 or 2 (RR: 1.95, 95% CI: 1.13-3.37; P = 0.02) and BARC bleeding type 3 or 5 (RR: 1.70, 95% CI: 1.17-2.48; P = 0.006) were significantly higher with ticagrelor.

CONCLUSIONS

When compared with clopidogrel, even though ticagrelor was not associated with higher risk of adverse cardiovascular outcomes in these patients with CKD, it was associated with significantly higher BARC bleeding. Therefore, the safety outcomes of ticagrelor still require further evaluation in patients with CKD. Nevertheless, this hypothesis should only be confirmed with more powerful results that could usually only be achieved using large-scale randomized trials.

Antiplatelet agents for chronic kidney disease

BACKGROUND

Antiplatelet agents are widely used to prevent cardiovascular events. The risks and benefits of antiplatelet agents may be different in people with chronic kidney disease (CKD) for whom occlusive atherosclerotic events are less prevalent, and bleeding hazards might be increased. This is an update of a review first published in 2013.

OBJECTIVES

To evaluate the benefits and harms of antiplatelet agents in people with any form of CKD, including those with CKD not receiving renal replacement therapy, patients receiving any form of dialysis, and kidney transplant recipients.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies up to 13 July 2021 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

We selected randomised controlled trials of any antiplatelet agents versus placebo or no treatment, or direct head-to-head antiplatelet agent studies in people with CKD. Studies were included if they enrolled participants with CKD, or included people in broader at-risk populations in which data for subgroups with CKD could be disaggregated.

DATA COLLECTION AND ANALYSIS

Four authors independently extracted data from primary study reports and any available supplementary information for study population, interventions, outcomes, and risks of bias. Risk ratios (RR) and 95% confidence intervals (CI) were calculated from numbers of events and numbers of participants at risk which were extracted from each included study. The reported RRs were extracted where crude event rates were not provided. Data were pooled using the random-effects model. Confidence in the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

MAIN RESULTS

We included 113 studies, enrolling 51,959 participants; 90 studies (40,597 CKD participants) compared an antiplatelet agent with placebo or no treatment, and 29 studies (11,805 CKD participants) directly compared one antiplatelet agent with another. Fifty-six new studies were added to this 2021 update. Seven studies originally excluded from the 2013 review were included, although they had a follow-up lower than two months. Random sequence generation and allocation concealment were at low risk of bias in 16 and 22 studies, respectively. Sixty-four studies reported low-risk methods for blinding of participants and investigators; outcome assessment was blinded in 41 studies. Forty-one studies were at low risk of attrition bias, 50 studies were at low risk of selective reporting bias, and 57 studies were at low risk of other potential sources of bias. Compared to placebo or no treatment, antiplatelet agents probably reduces myocardial infarction (18 studies, 15,289 participants: RR 0.88, 95% CI 0.79 to 0.99, I² = 0%; moderate certainty). Antiplatelet agents has uncertain effects on fatal or nonfatal stroke (12 studies, 10.382 participants: RR 1.01, 95% CI 0.64 to 1.59, I² = 37%; very low certainty) and may have little or no effect on death from any cause (35 studies, 18,241 participants: RR 0.94, 95 % CI 0.84 to 1.06, I² = 14%; low certainty). Antiplatelet therapy probably increases major bleeding in people with CKD and those treated with haemodialysis (HD) (29 studies, 16,194 participants: RR 1.35, 95% CI 1.10 to 1.65, I² = 12%; moderate certainty). In addition, antiplatelet therapy may increase minor bleeding in people with CKD and those treated with HD (21 studies, 13,218 participants: RR 1.55, 95% CI 1.27 to 1.90, I² = 58%; low certainty). Antiplatelet treatment may reduce early dialysis vascular access thrombosis (8 studies, 1525 participants) RR 0.52, 95% CI 0.38 to 0.70; low certainty). Antiplatelet agents may reduce doubling of serum creatinine in CKD (3 studies, 217 participants: RR 0.39, 95% CI 0.17 to 0.86, I² = 8%; low certainty). The treatment effects of antiplatelet agents on stroke, cardiovascular death, kidney failure, kidney transplant graft loss, transplant rejection, creatinine clearance, proteinuria, dialysis access failure, loss of primary unassisted patency, failure to attain suitability for dialysis, need of intervention and cardiovascular hospitalisation were uncertain. Limited data were available for direct head-to-head comparisons of antiplatelet drugs, including prasugrel, ticagrelor, different doses of clopidogrel, abciximab, defibrotide, sarpogrelate and beraprost.

AUTHORS' CONCLUSIONS

Antiplatelet agents probably reduced myocardial infarction and increased major bleeding, but do not appear to reduce all-cause and cardiovascular death among people with CKD and those treated with dialysis. The treatment effects of antiplatelet agents compared with each other are uncertain.

Relationship Between Dietary Phosphate Intake and Biomarkers of Bone and Mineral Metabolism in Australian Adults With Chronic Kidney Disease

OBJECTIVE

Higher serum phosphate is associated with increased adverse outcomes including cardiovascular disease. Abnormalities of bone and mineral metabolism in chronic kidney disease (CKD), including higher serum phosphate, are important risk factors for increased cardiovascular disease. Associations between dietary phosphate intake and biochemical and cardiovascular parameters in non-dialysis CKD patients, however, have not been adequately studied. This study aimed to explore associations between phosphate intake and biomarkers of bone and mineral metabolism and intermediate cardiovascular markers in adults with stage 3-4 CKD.

DESIGN AND METHODS

One hundred thirty-two participants enrolled in the IMpact of Phosphate Reduction On Vascular End-points in Chronic Kidney Disease trial were invited to participate in this sub-study. At baseline, dietary phosphate intake and its source (animal, plant, or a mixture of animal and plant) were determined using a 7-day self-administered diet food record, and measurements were made of serum and urinary phosphate, serum calcium, parathyroid hormone, fibroblast growth factor-23, and the intermediate cardiovascular markers pulse wave velocity (PWV) and abdominal aortic calcification. The relationships between dietary phosphate intake and these bone metabolism and cardiovascular markers were explored using Pearson's correlation and linear regression. The effect of source of phosphate intake was analyzed using compositional data analysis.

RESULTS

Ninety participants (age 64 ± 12 years, 68% male, estimated glomerular filtration rate 26.6 ± 7.6 mL/min/1.73 m², daily phosphate intake 1,544 ± 347 mg) completed the study. Correlations among dietary phosphate intake and biochemical measures, PWV, and abdominal aortic calcification ranged from r = -0.13 to r = +0.13. Linear regression showed no association between dietary phosphate measurements and biochemical or cardiovascular parameters. Source of phosphate intake was associated with PWV (P = .01), but not with other biomarkers of bone and mineral metabolism. Higher PWV values were associated with higher intake of plant-based relative to animal-based phosphate (1.058 [1.020-1.098], P = .003).

CONCLUSION

Levels of total dietary phosphate intake measured by dietary food record show no statistically significant relationship with biochemical markers of bone and mineral metabolism or intermediate cardiovascular markers. Higher PWV levels associated with higher intake of plant-based relative to animal-based phosphate intake were an unexpected finding and further research is needed in this area.

Copolymer-Based Fluorescence Nanosensor for In Situ Imaging of Homocysteine in the Liver and Kidney of Diabetic Mice

Homocysteine (Hcy) is one of the important biomarkers of clinical diagnosis, which is closely related to the occurrence and development of many diseases. Current analysis methods have difficulties in detecting Hcy in cells and living organisms. As a powerful technique, fluorescence methods combined the laser confocal imaging technology can achieve real-time visual tracking in cells and in vivo. Herein, we establish a conjugated copolymer-based fluorescence nanosensor (DPA-PFNP-Cu(II)) using the connected 2,7-dibromofluorene and 4,7-bis (2-bromothiophen-5-yl)-2-1-3-benzothiadiazole as the main chain. The competitive coordination between Hcy and Cu(II) allows the fluorescence of the polymer off to on. Finally, the nanosensor is applied for in situ imaging of Hcy levels in the kidney and liver of diabetic mice and is found that Hcy levels were positively correlated with the degree of diabetes. Notably, the depth of tissue penetration of the nanosensor enables Hcy detection of the liver and kidney through in vivo imaging without damage. Two-photon imaging and in vivo imaging achieve consistent results, which correct each other, improving the accuracy of the test result. The present works provide a new imaging technique for studying the occurrence and development of diabetes and screening of new drugs for treatment at the living level.

Receptor for Advanced Glycation End Products is Involved in Platelet Hyperactivation and Arterial Thrombosis during Chronic Kidney Disease

BACKGROUND

 Chronic kidney disease (CKD) is associated with a high cardiovascular mortality due to increased rates of vascular lesions and thrombotic events, as well as serum accumulation of uremic toxins. A subgroup of these toxins (advanced glycation end products [AGEs] and S100 proteins) can interact with the receptor for AGEs (RAGE). In this study, we analyzed the impact of CKD on platelet function and arterial thrombosis, and the potential role of RAGE in this process.

METHODS

 Twelve weeks after induction of CKD in mice, platelet function and time to complete carotid artery occlusion were analyzed in four groups of animals (sham-operated, CKD, apolipoprotein E [Apoe]^-/-, and Apoe^-/-/Ager^-/- mice).

RESULTS

 Analysis of platelet function from whole blood and platelet-rich plasma showed hyperactivation of platelets only in CKD Apoe^-/- mice. There was no difference when experiments were done on washed platelets. However, preincubation of such platelets with AGEs or S100 proteins induced RAGE-mediated platelet hyperactivation. In vivo, CKD significantly reduced carotid occlusion times of Apoe^-/- mice (9.2 ± 1.1 vs. 11.1 ± 0.6 minutes for sham, p < 0.01). In contrast, CKD had no effect on occlusion times in Apoe^-/-/Ager^-/- mice. Moreover, carotid occlusion in Apoe^-/- CKD mice occurred significantly faster than in Apoe^-/-/Ager^-/- CKD mice (p < 0.0001).

CONCLUSION

 Our results show that CKD induces platelet hyperactivation, accelerates thrombus formation in a murine model of arterial thrombosis, and that RAGE deletion has a protective role. We propose that RAGE ligands binding to RAGE is involved in CKD-induced arterial thrombosis.

Cardiovascular Protection of Nephropathic Male Patients by Oral Food Supplements

Nephropathic patients show elevated cardiovascular morbidity and mortality compared to the general population. In order to delve deeper into the understanding of this phenomenon, it is necessary to recognize risk factors that are distinctive to the uremic state, such as oxidative stress and chronic low-grade inflammation. Moreover, gender differences have been reported in nephrology, as it has been observed that chronic kidney disease has higher prevalence in males than in females. The use of an oral food supplement (OFS) containing natural active compounds from Capsicum annuum L., Garcinia cambogia, Centella asiatica L., artichoke, and Aesculus hippocastanum L. which are virtually devoid from side effects, but rich in antioxidant and antiradical properties, could represent a valid therapeutic adjunct in the clinical management of nephropathic patients. Moreover, quantitative analysis performed in vitro on such compounds showed that they expressed good total antioxidant (7.28 gallic acid equivalents) and antiradical activity (above 80%). In this study, 23 male nephropathic patients and 10 age and body composition parameter matched healthy males (control group) were enrolled and took 3 cps/day of OFS for 5 weeks. At the end of the study, the nephropathic patient group showed a statistically significant reduction in the following laboratory parameters: total cholesterol (TC) (p = 0.044), atherogenic index TC/high-density lipoprotein cholesterol (p = 0.010), inflammatory parameters (C-reactive protein, p = 0.048, and erythrocyte sedimentation rate, p = 0.019), systolic (p = 0.044), and diastolic arterial blood pressure (p = 0.003). Regarding body composition, there was an increase in total body water % (p = 0.035) with redistribution of extracellular water % (p = 0.030) and intracellular water % (p = 0.049). In the control group, there was a reduction in fat mass % (p = 0.017) and extracellular water % (p = 0.047). Therefore, this OFS may represent a valid adjunct therapy to counteract comorbidities related to uremia.

Dietary Phosphate Consumption in Australians With Stages 3b and 4 Chronic Kidney Disease

OBJECTIVE

Dietary phosphate modification is a common therapy to treat hyperphosphatemia in individuals with chronic kidney disease (CKD). However, current dietary intake and common food sources of phosphate typically consumed by individuals with CKD are not well characterized. This study examined a cohort of CKD patients to determine total dietary intake and common food sources of phosphate, including phosphate additives.

DESIGN AND METHODS

Participants with CKD stages 3b and 4 recruited to a substudy of the "IMPROVE-CKD (IMpact of Phosphate Reduction On Vascular End-points in Chronic Kidney Disease) Study" completed a 7-day self-administered diet record at baseline. Diet histories were analyzed and daily phosphate intakes determined using FoodWorks V.9 (Xyris). The proportion of phosphate contributed by each food group was determined using the AUSNUT 2011-2013 Food Classification System. Ingredient lists of packaged food items consumed were reviewed to determine frequency of phosphate-based additives.

RESULTS

Ninety participants (mean eGFR 26.5 mL/min/1.73 m²) completed this substudy. Mean phosphate intake of participants was 1544 ± 347 mg/day, with 96% of individuals exceeding the recommended daily intake of phosphate (1000 mg/day). The highest sources of dietary phosphate were milk-based products (25%) and meat and poultry products/dishes (25%). Phosphate-based food additives were identified in 39% (n = 331/845) of packaged foods consumed by participants.

CONCLUSION

Dietary phosphate intakes of Australians with CKD are high and come from a variety of sources. Managing dietary phosphate intake requires a patient-centered, tailored approach with an emphasis on maintaining nutritional adequacy and awareness of phosphate additives.

Obstructive uropathy and unexpected death

A 66-year-old man was found dead at his home address. He had a history of poor nutrition with recent episodes of vomiting. At autopsy the decedent was cachexic with a body mass index (BMI) of 16.1. The major findings were of marked prostatomegaly (165 g) with obstruction to urine outflow resulting in dilatation and trabeculation of the bladder and bilateral hydroureteronephrosis. The bladder contained 1.5 l of yellow urine and the kidneys weighed only 109 g on the left and 125 g on the right (N = 140-160 g). Histological examination of the prostate revealed benign nodular hyperplasia. Biochemical analysis of vitreous humor demonstrated a creatinine of 1579 μmol/L (normal 45-90) and a urea of 133.4 mmol/L (normal 2.5-7.1). Despite genitourinary causes of sudden and/or unexpected death being rare in routine forensic practice, this case demonstrates significant underlying obstructive renal disease that resulted in sudden death and that had remained undiagnosed until the time of autopsy.

Can we IMPROVE cardiovascular outcomes through phosphate lowering in CKD? Rationale and protocol for the IMpact of Phosphate Reduction On Vascular End-points in Chronic Kidney Disease (IMPROVE-CKD) study

INTRODUCTION

Patients with chronic kidney disease (CKD) are at heightened cardiovascular risk, which has been associated with abnormalities of bone and mineral metabolism. A deeper understanding of these abnormalities should facilitate improved treatment strategies and patient-level outcomes, but at present there are few large, randomised controlled clinical trials to guide management. Positive associations between serum phosphate and fibroblast growth factor 23 (FGF-23) and cardiovascular morbidity and mortality in both the general and CKD populations have resulted in clinical guidelines suggesting that serum phosphate be targeted towards the normal range, although few randomised and placebo-controlled studies have addressed clinical outcomes using interventions to improve phosphate control. Early preventive measures to reduce the development and progression of vascular calcification, left ventricular hypertrophy and arterial stiffness are crucial in patients with CKD.

METHODS AND ANALYSIS

We outline the rationale and protocol for an international, multicentre, randomised parallel-group trial assessing the impact of the non-calcium-based phosphate binder, lanthanum carbonate, compared with placebo on surrogate markers of cardiovascular disease in a predialysis CKD population-the IM pact of P hosphate R eduction O n V ascular E nd-points (IMPROVE)-CKD study. The primary objective of the IMPROVE-CKD study is to determine if the use of lanthanum carbonate reduces the burden of cardiovascular disease in patients with CKD stages 3b and 4 when compared with placebo. The primary end-point of the study is change in arterial compliance measured by pulse wave velocity over a 96-week period. Secondary outcomes include change in aortic calcification and biochemical parameters of serum phosphate, parathyroid hormone and FGF-23 levels.

ETHICS AND DISSEMINATION

Ethical approval for the IMPROVE-CKD trial was obtained by each local Institutional Ethics Committee for all 17 participating sites in Australia, New Zealand and Malaysia prior to study commencement. Results of this clinical trial will be published in peer-reviewed journals and presented at conferences.

TRIAL REGISTRATION NUMBER

ACTRN12610000650099.

Mechanisms and Modulation of Oxidative/Nitrative Stress in Type 4 Cardio-Renal Syndrome and Renal Sarcopenia

Chronic kidney disease (CKD) is a public health problem and a recognized risk factor for cardiovascular diseases (CVD). CKD could amplify the progression of chronic heart failure leading to the development of type 4 cardio-renal syndrome (T4CRS). The severity and persistence of heart failure are strongly associated with mortality risk in T4CRS. CKD is also a catabolic state leading to renal sarcopenia which is characterized by the loss of skeletal muscle strength and physical function. Renal sarcopenia also promotes the development of CVD and increases the mortality in CKD patients. In turn, heart failure developed in T4CRS could result in chronic muscle hypoperfusion and metabolic disturbances leading to or aggravating the renal sarcopenia. The interplay of multiple factors (e.g., comorbidities, over-activated renin-angiotensin-aldosterone system [RAAS], sympathetic nervous system [SNS], oxidative/nitrative stress, inflammation, etc.) may result in the progression of T4CRS and renal sarcopenia. Among these factors, oxidative/nitrative stress plays a crucial role in the complex pathomechanism and interrelationship between T4CRS and renal sarcopenia. In the heart and skeletal muscle, mitochondria, nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, uncoupled nitric oxide synthase (NOS) and xanthine oxidase are major ROS sources producing superoxide anion (O2^·−) and/or hydrogen peroxide (H₂O₂). O2^·− reacts with nitric oxide (NO) forming peroxynitrite (ONOO⁻) which is a highly reactive nitrogen species (RNS). High levels of ROS/RNS cause lipid peroxidation, DNA damage, interacts with both DNA repair enzymes and transcription factors, leads to the oxidation/nitration of key proteins involved in contractility, calcium handling, metabolism, antioxidant defense mechanisms, etc. It also activates the inflammatory response, stress signals inducing cardiac hypertrophy, fibrosis, or cell death via different mechanisms (e.g., apoptosis, necrosis) and dysregulates autophagy. Therefore, the thorough understanding of the mechanisms which lead to perturbations in oxidative/nitrative metabolism and its relationship with pro-inflammatory, hypertrophic, fibrotic, cell death and other pathways would help to develop strategies to counteract systemic and tissue oxidative/nitrative stress in T4CRS and renal sarcopenia. In this review, we also focus on the effects of some well-known and novel pharmaceuticals, nutraceuticals, and physical exercise on cardiac and skeletal muscle oxidative/nitrative stress in T4CRS and renal sarcopenia.

Albuminuria, Reduced Kidney Function, and the Risk of ST - and non-ST-segment-elevation myocardial infarction

Background Chronic kidney disease is a recognized independent risk factor for cardiovascular disease, but whether the risks of ST-segment-elevation myocardial infarction ( STEMI ) and non-ST-segment-elevation myocardial infarction ( NSTEMI ) differ in the chronic kidney disease population is unknown. Methods and Results Using administrative data from Ontario, Canada, we examined patients ≥66 years of age with an outpatient estimated glomerular filtration rate ( eGFR ) and albuminuria measure for incident myocardial infarction from 2002 to 2015. Adjusted Fine and Gray subdistribution hazard models accounting for the competing risk of death were used. In 248 438 patients with 1.2 million person-years of follow-up, STEMI , NSTEMI , and death occurred in 1436 (0.58%), 4431 (1.78%), and 30 015 (12.08%) patients, respectively. The highest level of albumin-to-creatinine ratio (>30 mg/mmol) was associated with a 2-fold higher adjusted risk of both STEMI and NSTEMI among patients with eGFR ≥60 mL/(min·1.73 m2) compared to albumin-to-creatinine ratio <3 mg/mmol. The lowest level of eGFR (<30 mL/[min·1.73 m2]) was not associated with higher STEMI risk but with a 4-fold higher risk of NSTEMI compared to those with eGFR ≥60 mL/(min·1.73 m2). The lowest eGFR (<30 mL/[min·1.73 m2]) and highest albumin-to-creatinine ratio (>30 mg/mmol) were associated with a greater than 4-fold higher risk of both STEMI and NSTEMI (subdistribution hazard models [95% confidence interval] 4.53 [3.30-6.21] and 4.42 [3.67-5.32], respectively) compared to albumin-to-creatinine ratio <3 mg/mmol and eGFR ≥60 mL/(min·1.73 m2). Conclusions Elevations in albuminuria are associated with a higher risk of both NSTEMI and STEMI , regardless of kidney function, whereas reduced kidney function alone is associated with a higher NSTEMI risk.

Resistant hypertension: Renal denervation or intensified medical treatment?

Resistant hypertension (RH) can be diagnosed if blood pressure (BP) is not controlled with the combination of three antihypertensive drugs, including a diuretic, all at effective doses. Patients affected by this condition exhibit a marked increase in the risk of cardiovascular and renal morbid and fatal events. They also exhibit an increased activity of the sympathetic nervous system which is likely to importantly contribute at the renal and other vascular levels to the hypertensive state. Almost 10years ago renal denervation (RDN) by radiofrequency thermal energy delivery to the walls of the renal arteries was proposed for the treatment of RH. Several uncontrolled studies initially reported that this procedure substantially reduced the elevated BP values but this conclusion has not been supported by a recent randomized control trial, which has almost marginalized this therapeutic approach. A revival, however, is under way because of recent positive findings and technical improvement that hold promise to make renal denervation more complete. The antihypertensive efficacy and overall validity of RDN will have to be tested against drug treatment of RH. Several studies indicate that an excess of aldosterone production contributes to RH and recent evidence documents indisputably that anti-aldosterone agents such as spironolactone can effectively control BP in many RH patients, although with some side effects that require close patients' monitoring. At present, it is advisable to treat RH with the addition of an anti-aldosterone agent. If BP control is not achieved or serious side effects become manifest RDN may then be considered.

Cardiovascular Risk in Hemodialysis Patients: A Mechanistic Approach

A new formula is proposed to express the excess burden of cardiovascular risk faced by hemodialysis patients as a function of various inherent, acquired and potentially modifiable factors. The proposed equation CVRHD = CVRB X f(([CKD+HD]/[HDtech+Dr])+X) includes the terms: CVRHD (cardiovascular risk in hemodialysis patients); CVRB (baseline cardiovascular risk); CKD (risk associated with chronic kidney disease); HD (risks associated with the process of hemodialysis); HDtech (benefits of new hemodialysis technologies); Dr (benefits of drug therapies) and X (unknown or putative factors influencing cardiovascular morbidity).

We review the various factors included in this proposed formula, touching upon the epidemiology, pathophysiology and therapeutic implications, including possible strategies to modify risk. As is apparent from the formula, CKD and HD in particular act as risk multipliers in augmenting or amplifying the baseline cardiovascular risk, while new hemodialysis technologies may provide an opportunity for “cardioprotective dialysis.” Drug treatment may serve to mitigate some of the risk unique to this population.

Ultrasmall polymeric nanocarriers for drug delivery to podocytes in kidney glomerulus

We explored the use of new drug-loaded nanocarriers and their targeted delivery to the kidney glomerulus and in particular to podocytes, in order to overcome the failure of current therapeutic regimens in patients with proteinuric (i.e. abnormal amount of proteins in the urine) diseases. Podocytes are glomerular cells which are mainly responsible for glomerular filtration and are primarily or secondarily involved in chronic kidney diseases. Therefore, the possibility to utilise a podocyte-targeted drug delivery could represent a major breakthrough in kidney disease research, particularly in terms of dosage reduction and elimination of systemic side effects of current therapies. Four-arm star-shaped polymers, with/without a hydrophobic poly-ε-caprolactone core and a brush-like polyethylene glycol (PEG) hydrophilic shell, were synthesised by controlled/living polymerisation (ROP and ATRP) to allow the formation of stable ultrasmall colloidal nanomaterials of tuneable size (5-30nm), which are able to cross the glomerular filtration barrier (GFB). The effects of these nanomaterials on glomerular cells were evaluated in vitro. Nanomaterial accumulation and permeability in the kidney glomerulus were also assessed in mice under physiological and pathological conditions. Drug (dexamethasone) encapsulation was performed in order to test loading capacity, release kinetics, and podocyte repairing effects. The marked efficacy of these drug-loaded nanocarriers in repairing damaged podocytes may pave the way for developing a cell-targeted administration of new and traditional drugs, increasing efficacy and limiting side effects.

Pathophysiology of the cardio-renal syndromes types 1-5: An uptodate

According to the recent definition proposed by the Consensus conference on Acute Dialysis Quality Initiative Group, the term cardio-renal syndrome (CRS) has been used to define different clinical conditions in which heart and kidney dysfunction overlap. Type 1 CRS (acute cardio- renal syndrome) is characterized by acute worsening of cardiac function leading to AKI (5, 6) in the setting of active cardiac disease such as ADHF, while type - 2 CRS occurs in a setting of chronic heart disease. Type 3 CRS is closely link to acute kidney injury (AKI), while type 4 represent cardiovascular involvement in chronic kidney disese (CKD) patients. Type 5 CRS represent cardiac and renal involvement in several diseases such as sepsis, hepato - renal syndrome and immune - mediated diseases.

Methionine sulfoxides in serum proteins as potential clinical biomarkers of oxidative stress

Oxidative stress contributes to the pathophysiology of a variety of diseases, and circulating biomarkers of its severity remains a topic of great interest for researchers. Our peptidomic strategy enables accurate and reproducible analysis of circulating proteins/peptides with or without post-translational modifications. Conventional wisdom holds that hydrophobic methionines exposed to an aqueous environment or experimental handling procedures are vulnerable to oxidation. However, we show that the mass spectra intensity ratio of oxidized to non-oxidized methionine residues in serum tryptic proteins can be accurately quantified using a single drop of human serum and give stable and reproducible results. Our data demonstrate that two methionine residues in serum albumin (Met-111 and Met-147) are highly oxidized to methionine sulfoxide in patients with diabetes and renal failure and in healthy smokers versus non-smoker controls. This label-free mass spectrometry approach to quantify redox changes in methionine residues should facilitate the identification of additional circulating biomarkers suitable for predicting the development or progression of human diseases.

Adiponectin, leptin, nitric oxide, and C-reactive protein levels in kidney transplant recipients: comparison with the hemodialysis and chronic renal failure

BACKGROUND

Cardiovascular disease (CVD) is the leading cause of mortality and morbidity in patients with chronic kidney disease (CKD) including kidney transplant recipients (KTR). Secondary lipid metabolism disorders, endothelial dysfunction, and inflammation enhance the risk of CVD development in these patients. The aim of the present study was to investigate the lipid profile, adiponectin, leptin, nitric oxide (NO), and high sensitivity C-reactive protein (hs-CRP) levels in KTR and to compare these parameters with those of the patients with chronic renal failure (CRF), hemodialysis (HD) patients, and healthy controls.

METHODS

Serum adiponectin and leptin levels were measured by radioimmunoassay; hs-CRP was determined immunoturbidimetrically. Determination of NO was based on the Griess reaction.

RESULTS

Compared with the control group, serum NO and adiponectin levels were significantly higher in the KTR, CRF, and HD groups; hs-CRP levels were significantly higher in the KTR and HD groups; leptin levels were significantly higher in the KTR. In addition, serum NO level was significantly higher in the KTR compared to CRF cases. Adiponectin correlated positively with high density lipoprotein-cholesterol in the control and patient groups. A positive correlation was observed between hs-CRP and NO in the KTR and the patients with CRF. Serum adiponectin levels were inversely correlated with hs-CRP and leptin in the HD group.

CONCLUSION

KTR suffer from inflammation and accompanying changes in levels of adipocytokines and NO which contribute to the increased risk of CVD in these patients.

Cystatin C Predicts Incident Cardiovascular Disease in Twins

BACKGROUND

Cystatin C is associated with both renal function and atherosclerotic cardiovascular disease (ASCVD). We have previously shown a genetic correlation between cystatin C and prevalent ASCVD. The objective of this article is to study whether variation in cystatin C or creatinine predicts incident ASCVD when controlled for genetic factors.

METHODS AND RESULTS

The predictive value of cystatin C and creatinine for incident ASCVD was studied in 11 402 Swedish twins, free of CVD at baseline, in an adjusted Cox-regression model during a median follow-up of 71 months. Twin pairs discordant for incident stroke, myocardial infarction and ASCVD during follow-up were identified and within-pair comparisons regarding cystatin C and creatinine levels were performed. We also investigated whether contact frequency and degree of shared environment influences were associated with similarity in cystatin C levels. In univariate analysis, cystatin C predicted incident ASCVD hazard ratio 1.57, 95% CI 1.47-1.67. When adjusted for traditional Framingham risk factors as covariates, cystatin C remained a predictor of incident stroke hazard ratio 1.45, 95% CI (1.25-1.70), ASCVD hazard ratio 1.26, 95% CI (1.13-1.41), and myocardial infarction hazard ratio 1.16, 95% CI (1.01-1.33). In twins discordant for incident stroke, cystatin C at baseline was higher in the twin who experienced a stroke compared to the healthy co-twin (1.11±0.3 mg/L versus 1.06±0.3 mg/L), whereas creatinine was lower in the twin who developed CVD compared to their healthy co-twins (76.1±16.9 μmol/L versus 79.4±20.3 μmol/L).

CONCLUSIONS

Variation in cystatin C relates to incident ASCVD and to stroke when adjusted for genetic confounding. In identical twins, cystatin C may be a sensitive marker of early hypertensive end-organ damage and small-vessel disease, whereas creatinine level may reflect nutritional status. The findings in disease-discordant monozygotic twins indicate that unique, possibly preventable, environmental factors are important.

Signaling of Serum Amyloid A Through Receptor for Advanced Glycation End Products as a Possible Mechanism for Uremia-Related Atherosclerosis

OBJECTIVE

Cardiovascular disease is the leading cause of death in patients with end-stage renal disease. Serum amyloid A (SAA) is an acute phase protein and a binding partner for the multiligand receptor for advanced glycation end products (RAGE). We investigated the role of the interaction between SAA and RAGE in uremia-related atherogenesis.

APPROACH AND RESULTS

We used a mouse model of uremic vasculopathy, induced by 5 of 6 nephrectomy in the Apoe(-/-) background. Sham-operated mice were used as controls. Primary cultures of Ager(+/+) and Ager(-/-) vascular smooth muscle cells (VSMCs) were stimulated with recombinant SAA, S100B, or vehicle alone. Relevance to human disease was assessed with human VSMCs. The surface area of atherosclerotic lesions at the aortic roots was larger in uremic Apoe(-/-) than in sham-operated Apoe(-/-) mice (P<0.001). Furthermore, atherosclerotic lesions displayed intense immunostaining for RAGE and SAA, with a pattern similar to that of α-SMA. Ager transcript levels in the aorta were 6× higher in uremic animals than in controls (P<0.0001). Serum SAA concentrations were higher in uremic mice, not only after 4 weeks of uremia but also at 8 and 12 weeks of uremia, than in sham-operated animals. We investigated the functional role of RAGE in uremia-induced atherosclerosis further, in animals lacking RAGE. We found that the induction of uremia in Apoe(-/-) Ager(-/-) mice did not accelerate atherosclerosis. In vitro, the stimulation of Ager(+/+) but not of Ager(-/-) VSMCs with SAA or S100B significantly induced the production of reactive oxygen species, the phosphorylation of AKT and mitogen-activated protein kinase-extracellular signal-regulated kinases and cell migration. Reactive oxygen species inhibition with N-acetyl cysteine significantly inhibited both the phosphorylation of AKT and the migration of VSMCs. Similar results were obtained for human VSMCs, except that the phosphorylation of mitogen-activated protein kinase-extracellular signal-regulated kinases, rather than of AKT, was subject to specific redox-regulation by SAA and S100B. Furthermore, human aortic atherosclerotic sections were positively stained for RAGE and SAA.

CONCLUSIONS

Uremia upregulates SAA and RAGE expression in the aortic wall and in atherosclerotic lesions in mice. Ager(-/-) animals are protected against the uremia-induced acceleration of atherosclerosis. SAA modulates the functions of murine and human VSMCs in vitro in a RAGE-dependent manner. This study, therefore, identifies SAA as a potential new uremic toxin involved in uremia-related atherosclerosis through interaction with RAGE.

Animal Models to Study Links between Cardiovascular Disease and Renal Failure and Their Relevance to Human Pathology

The close association between cardiovascular pathology and renal dysfunction is well documented and significant. Patients with conventional risk factors for cardiovascular disease like diabetes and hypertension also suffer renal dysfunction. This is unsurprising if the kidney is simply regarded as a “modified blood vessel” and thus, traditional risk factors will affect both systems. Consistent with this, it is relatively easy to comprehend how patients with either sudden or gradual cardiac and or vascular compromise have changes in both renal hemodynamic and regulatory systems. However, patients with pure or primary renal dysfunction also have metabolic changes (e.g., oxidant stress, inflammation, nitric oxide, or endocrine changes) that affect the cardiovascular system. Thus, cardiovascular and renal systems are intimately, bidirectionally and inextricably linked. Whilst we understand several of these links, some of the mechanisms for these connections remain incompletely explained. Animal models of cardiovascular and renal disease allow us to explore such mechanisms, and more importantly, potential therapeutic strategies. In this article, we review various experimental models used, and examine critically how representative they are of the human condition.

Why do young people with chronic kidney disease die early?

Cardiovascular disease poses the greatest risk of premature death seen among patients with chronic kidney disease (CKD). Up to 50% of mortality risk in the dialysis population is attributable to cardiovascular disease and the largest relative excess mortality is observed in younger patients. In early CKD, occlusive thrombotic coronary disease is common, but those who survive to reach end-stage renal failure requiring dialysis are more prone to sudden death attributable mostly to sudden arrhythmic events and heart failure related to left ventricular hypertrophy, coronary vascular calcification and electrolyte disturbances. In this review, we discuss the basis of the interaction of traditional risk factors for cardiovascular disease with various pathological processes such as endothelial dysfunction, oxidative stress, low grade chronic inflammation, neurohormonal changes and vascular calcification and stiffness which account for the structural and functional cardiac changes that predispose to excess morbidity and mortality in young people with CKD.

Cross-talk between endothelin-1 and mineral metabolism in hemodialysis patients: a cross-sectional study

Background:

Endotheline-1 (ET-1), an endothelial mediator, influences on mineral metabolism; especially vascular calcification in uremic patients.

Objectives:

The aim of the present study was to evaluate of ET-1, high-sensitivity C-reactive protein (hs-CRP) and mineral metabolites as the main factors for vascular calcification and inflammation in hemodialysis (HD) patients.

Patients and Methods:

In this cross-sectional study, 46 chronic stable HD patients were selected from nephrology departments of Tabriz University of Medical Sciences affiliated hospitals and classified based on phosphorus (P), Ca-P product (Ca × P) and intact Parathyroid Hormone (iPTH) levels. We evaluated fasting serum ET-1and hs-CRP levels by the standard methods and compared with 46 healthy control subjects.

Results:

The levels of serum hs-CRP and ET-1 were significantly higher in the patient’s group compared with controls (4.40 ± 1.26 vs. 1.38 ± 1.61, P < 0.0001, and 2.31 ± 0.87 vs. 0.75 ± 0.48, P < 0.0001, respectively) and with regard to Ca × P product cut-off point (3.99 ± 0.78 vs. 5.33 ± 1.64, P < 0.0001, and 2 ± 0.73 vs. 3.04 ± 0.73, P < 0.0001 respectively). ET-1 was correlated significantly with hs-CRP level (r = 0.776, P < 0.0001). Serum P, Ca × P and iPTH levels directly and Ca indirectly were correlated with serum ET-1 in HD patients (r = 0.932, P < 0.0001, r = 0.766, P < 0.0001, r = 0.514, P < 0.0001, r = -0.538, P < 0.0001 respectively). Multiple regression analysis demonstrated that serum P were independently associated with ET-1 levels (β = 0.932, P < 0.0001).

Conclusions:

Serum P and iPTH levels were independently associated with ET-1 and those may play a role in development of endothelial dysfunction in chronic kidney disease.

Effect of different hemodialyzers on serum levels of interleukin-6, interleukin-10 and interleukin-18

BACKGROUND

The blood and membrane contact during dialysis may elicit an immune reaction. The current study looked at the impact of different dialyzers on blood levels of cytokines.

METHODS

During the first month, randomly selected patients were treated with one dialyzer (PF-170H) and then crossed over to another dialyzer (FLX-18GW) during the next month. Pre- and postdialysis blood samples were assayed for interleukin (IL)-6, IL-10 and IL-18.

RESULTS

A significant drop of postdialysis systolic blood pressure (pre vs. post 156.4 ± 31.8 vs. 143.1 ± 24.8 mm Hg, p = 0.014) and diastolic pressure (80.7 ± 12.7 vs. 73.4 ± 10.9 mm Hg, p = 0.002) were found when patients were dialyzed with PF-170H. A significant increase of postdialysis IL-18 levels was found in both groups (pre vs. post 605.5 ± 278.6 vs. 690.6 ± 315.3 pg/ml, p = 0.016, for PF-170H and 556.4 ± 231.0 vs. 647.3 ± 282.6 pg/ml, p = 0.067, for FLX-18GW). There was a positive correlation between IL-6 and IL-10 levels (p < 0.0001).

CONCLUSION

We demonstrated a significant increase of postdialysis serum IL-18 level when either dialyzer was used. There is a strong correlation between serum levels of IL-6 and IL-10.

Proteinuria and its relation to cardiovascular disease

Chronic kidney disease (CKD) and its associated morbidity pose a worldwide health problem. As well as risk of endstage renal disease requiring renal replacement therapy, cardiovascular disease is the leading cause of premature death among the CKD population. Proteinuria is a marker of renal injury that can often be detected earlier than any tangible decline in glomerular filtration rate. As well as being a risk marker for decline in renal function, proteinuria is now widely accepted as an independent risk factor for cardiovascular morbidity and mortality. This review will address the prognostic implications of proteinuria in the general population as well as other specific disease states including diabetes, hypertension and heart failure. A variety of pathophysiological mechanisms that may underlie the relationship between renal and cardiovascular disease have been proposed, including insulin resistance, inflammation, and endothelial dysfunction. As proteinuria has evolved into a therapeutic target for cardiovascular risk reduction in the clinical setting we will also review therapeutic strategies that should be considered for patients with persistent proteinuria.

Association of cholesterol levels with mortality and cardiovascular events among patients with CKD and different amounts of proteinuria

BACKGROUND AND OBJECTIVES

Malnutrition and/or inflammation may modify the risk relationship of total cholesterol with cardiovascular disease in CKD patients. However, it is unclear whether the relationship of total cholesterol with cardiovascular events and mortality varies by proteinuria.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

This study enrolled 3303 patients with CKD stages 3-5 from a medical center and a regional hospital between November of 2002 and May of 2009 and followed the patients until July of 2010.

RESULTS

During a median 2.8-year follow-up, there were 471 (14.3%) deaths and 545 (16.5%) cardiovascular events. In an adjusted Cox model, the two highest quartiles of total cholesterol (hazard ratio, 1.90; 95% confidence interval, 1.16 to 3.13 and hazard ratio, 2.00; 95% confidence interval, 1.18 to 3.39 versus quartile 1, respectively) were associated with a significant higher risk of all-cause mortality in patients with urine protein-to-creatinine ratio<1 g/g (n=1535), but this higher risk was not seen in those patients with urine protein-to-creatinine ratio ≥ 1 g/g (n=1768; hazard ratio, 0.75; 95% confidence interval, 0.53 to 1.07 and hazard ratio, 0.70; 95% confidence interval, 0.49 to 1.02 versus quartile 1, respectively). The interaction between total cholesterol and proteinuria with all-cause mortality was significant (interaction, P=0.05). However, the relationship between total cholesterol and cardiovascular events did not significantly differ by proteinuria (interaction, P=0.91).

CONCLUSIONS

The association between cholesterol and mortality is different among patients with different levels of proteinuria. Large-scale clinical trials to evaluate the mortality benefit should specifically target lowering hypercholesterolemia in CKD patients with different levels of proteinuria.

Sex differences in cardiovascular outcomes in patients with incident hypertension

BACKGROUND

The time of initial hypertension diagnosis represents an opportunity to assess subsequent risk of adverse cardiovascular outcomes. The extent to which women and men with newly identified hypertension are at a similar risk for adverse cardiovascular events, including chronic kidney disease (CKD), is not well known.

METHODS

Among women and men with incident hypertension from 2001 to 2006 enrolled in the Cardiovascular Research Network (CVRN) Hypertension Registry, we compared incident events including all-cause death; hospitalization for myocardial infarction (MI), heart failure or stroke; and the development of CKD. Multivariable models were adjusted for patient demographic and clinical characteristics.

RESULTS

Among 177,521 patients with incident hypertension, 55% were women. Compared with men, women were older, more likely white and had more kidney disease at baseline. Over median 3.2 years (interquartile range 1.6-4.8) of follow-up, after adjustment, women were equally likely to be hospitalized for heart failure [hazard ratio 0.90, 95% confidence interval (CI) 0.76-1.07] and were significantly less likely to die of any cause (hazard ratio 0.85, 95% CI 0.80-0.90) or be hospitalized for MI (hazard ratio 0.44, 95% CI 0.39-0.50) or stroke (hazard ratio 0.68, 95% CI 0.60-0.77) compared with men. Women were significantly more likely to develop CKD (9.60 vs. 7.15%; adjusted hazard ratio 1.17, 95% CI 1.12-1.22) than men.

CONCLUSION

In this cohort with incident hypertension, women were more likely to develop CKD and less likely to develop other cardiovascular outcomes compared with men. Future studies should investigate the potential reasons for these sex differences.

Antiplatelet agents for chronic kidney disease

BACKGROUND

Antiplatelet agents are widely used to prevent cardiovascular events. The risks and benefits of antiplatelet treatment may be different in people with chronic kidney disease (CKD) for whom occlusive atherosclerotic events are less prevalent, and bleeding hazards might be increased.

OBJECTIVES

To summarise the effects of antiplatelet treatment (antiplatelet agent versus control or other antiplatelet agent) for the prevention of cardiovascular and adverse kidney outcomes in individuals with CKD.

SEARCH METHODS

In January 2011 we searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and the Cochrane Renal Group's Specialised Register without language restriction.

SELECTION CRITERIA

We selected randomised controlled trials of any antiplatelet treatment versus placebo or no treatment, or direct head-to-head antiplatelet agent studies in people with CKD. Studies were included if they enrolled participants with CKD, or included people in broader at-risk populations in which data for subgroups with CKD could be disaggregated.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data from primary study reports and any available supplementary information for study population, interventions, outcomes, and risks of bias. Risk ratios (RR) and 95% confidence intervals (CI) were calculated from numbers of events and numbers of participants at risk which were extracted from each included study. The reported RRs were extracted where crude event rates were not provided. Data was pooled using the random-effects model.

MAIN RESULTS

We included 50 studies, enrolling 27,139 participants; 44 studies (21,460 participants) compared an antiplatelet agent with placebo or no treatment, and six studies (5679 participants) directly compared one antiplatelet agent with another. Compared to placebo or no treatment, antiplatelet agents reduced the risk of myocardial infarction (17 studies; RR 0.87, 95% CI 0.76 to 0.99), but not all-cause mortality (30 studies; RR 0.93, 95% CI 0.81 to 1.06), cardiovascular mortality (19 studies; RR 0.89, 95% CI 0.70 to 1.12) or stroke (11 studies; RR 1.00, 95% CI 0.58 to 1.72). Antiplatelet agents increased the risk of major (27 studies; RR 1.33, 95% CI 1.10 to 1.65) and minor bleeding (18 studies; RR 1.49, 95% CI 1.12 to 1.97). In terms of dialysis access outcomes, antiplatelet agents reduced access thrombosis or patency failure but had no effect on suitability for dialysis. Meta-regression analysis indicated no differences in the relative benefit or harms of treatment (risk of all-cause mortality, myocardial infarction, or major bleeding) by type of antiplatelet agent or stage of CKD. Limited data were available for direct head-to-head comparisons of antiplatelet drugs, treatment in kidney transplant recipients, primary prevention, or risk of ESKD.

AUTHORS' CONCLUSIONS

Antiplatelet agents reduce myocardial infarction but increase major bleeding. Risks may outweigh harms among people with low annual risks of cardiovascular events, including those with early stages of CKD who do not have clinically-evident occlusive cardiovascular disease.

Uremic serum and solutes increase post-vascular interventional thrombotic risk through altered stability of smooth muscle cell tissue factor

BACKGROUND

Stent thrombosis (ST), a postinterventional complication with a mortality rate of 50%, has an incidence that rises precipitously in patients at risk. Chronic renal failure and end-stage renal disease have emerged as particularly strong ST risk factors, yet the mechanism remains elusive. Tissue factor (TF) is a crucial mediator of injury-related thrombosis and has been implicated for ST. We posit that uremia modulates TF in the local vessel wall to induce postinterventional thrombosis in patients with end-stage renal disease.

METHODS AND RESULTS

As a model of the de-endothelialized, postinterventional state, we exposed primary human vascular smooth muscle cells (vSMCs) pretreated with uremic serum (obtained from ESRD patients on hemodialysis) to coronary-like blood flow. vSMC TF expression, activity, stability, and posttranslational modification were examined after vSMCs were treated with uremic serum or solutes. We found significantly greater clot formation after uremic serum exposure, which was substantially reduced with the prior treatment with anti-TF neutralizing antibody. Uremic sera induced 2- to 3-fold higher TF expression and activity in vSMCs independent of diabetes mellitus. Relevant concentrations of isolated uremic solutes such as indole-3-acetic acid (3.5 μg/mL), indoxyl sulfate (25 μg/mL), and uric acid (80 μg/mL) recapitulated these effects in cell culture and the flow loop model. We show further that TF undergoes ubiquitination at baseline and that uremic serum, indole-3-acetic acid, and indoxyl sulfate significantly prolong TF half-life by inhibiting its ubiquitination.

CONCLUSIONS

The uremic milieu is profoundly thrombogenic and upregulates vSMC TF levels by increasing TF stability and decreasing its ubiquitination. Together, these data demonstrate for the first time that the posttranslational regulation of TF in uremia may have a causative role in the increased ST risk observed in uremic patients. These data suggest that interventions that reduce vSMC TF may help to prevent ST and that uremic solutes should be considered as novel risk factors for ST in patients with chronic renal failure.

Coronary artery calcification in kidney transplant recipients with long-term follow-up

OBJECTIVES

Kidney transplantation (KT) is associated with increased incidence of hypertension, hyperlipidemia, metabolic syndrome, and posttransplant diabetes mellitus that promote the development of coronary artery calcification (CAC). The aim of the current study was to elucidate the extent of CAC and its risk factors among KT patients.

METHODS

A cross-sectional study was performed to evaluate the severity of CAC in our KT patients. Multidetector computed tomography was performed to assess the coronary artery calcium score (CACS). Patients were further stratified according to the CACS as: group 1: 0-10, group 2: 11-100, group 3: 101-300, group 4: 301-1000, and group 5: >1000. Clinical as well as demographic data were compared among groups. Linear regression analysis was performed to determine factors that were associated with CAC.

RESULTS

A total of 99 patients were enrolled in the study. The mean age was 53.5 ± 11.8 years and duration of follow-up post-KT was 11.2 ± 5.9 years. The distribution of CACS in groups 1 through 5 was: 41.4%, 20.2%, 11.1%, 15.2%, and 12.1%, respectively. A significantly higher CACS was found in males, patients with pretransplant diabetes mellitus, older current age, older age at KT, hypertension, higher body weight, higher fasting plasma sugar level and lower high-density lipoprotein (HDL) cholesterol. Twenty-nine (29.3%) patients fulfilled criteria for metabolic syndrome (MS). The CACS was significantly higher in patients with MS than in those without MS. An incremental CACS was found to be correlated with increasing number of MS components (P = .003). Multivariate linear regression revealed that female gender, current age, hypertension, and HDL cholesterol were associated with CAC.

CONCLUSION

KT was associated with high CACS in a significant proportion of patients with long-term follow-up. Several risk factors were identified. Some of them were potentially treatable and should be taken into consideration in the management of KT recipients.

Cardio-renal syndrome type 4: epidemiology, pathophysiology and treatment

Cardiovascular diseases such as coronary artery disease, congestive heart failure, arrhythmia, and sudden cardiac death represent the leading causes of morbidity and mortality in patients with CKD, increasing sharply as patients approach end-stage renal disease. The pathogenesis includes a complex, bidirectional interaction between the heart and kidneys that encompasses traditional and nontraditional risk factors, and has been termed cardio-renal syndrome type 4. In this review, an overview of the epidemiology and scope of this problem is provided, some suggested mechanisms for the pathophysiology of this disorder are discussed, and some of the key treatment strategies are described, with particular focus on recent clinical trials, both negative and positive.

Antioxidant and renoprotective activity of chitosan in nephrectomized rats

The effect of chitosan on oxidative stress and chronic renal failure was investigated using 5/6 nephrectomized rats. The ingestion of chitosan over a 4-week period resulted in a significant decrease in total body weight, glucose, serum creatinine and indoxyl sulfate levels (P=0.0011, P=0.0006, P=0.0012, and P=0.0005, respectively), compared with the non-treated nephrectomized group. The ingestion of chitosan also resulted in a lowered ratio of oxidized to reduced albumin (P=0.003) and an increase in biological antioxidant potential (P=0.023). Interestingly, the oxidized albumin ratio was correlated with serum indoxyl sulfate levels in vivo. These results suggest that the ingestion of chitosan results in a significant reduction in the levels of pro-oxidants, such as uremic toxins, in the gastrointestinal tract, thereby inhibiting the subsequent development of oxidative stress in the systemic circulation.

Incidence and prognosis of resistant hypertension in hypertensive patients

BACKGROUND

Despite a recent American Heart Association (AHA) consensus statement emphasizing the importance of resistant hypertension, the incidence and prognosis of this condition are largely unknown.

METHODS AND RESULTS

This retrospective cohort study in 2 integrated health plans included patients with incident hypertension in whom treatment was begun between 2002 and 2006. Patients were followed up for the development of resistant hypertension based on AHA criteria of uncontrolled blood pressure despite use of ≥3 antihypertensive medications, with data collected on prescription filling information and blood pressure measurement. We determined incident cardiovascular events (death or incident myocardial infarction, heart failure, stroke, or chronic kidney disease) in patients with and without resistant hypertension with adjustment for patient and clinical characteristics. Among 205 750 patients with incident hypertension, 1.9% developed resistant hypertension within a median of 1.5 years from initial treatment (0.7 cases per 100 person-years of follow-up). These patients were more often men, were older, and had higher rates of diabetes mellitus than nonresistant patients. Over 3.8 years of median follow-up, cardiovascular event rates were significantly higher in those with resistant hypertension (unadjusted 18.0% versus 13.5%, P<0.001). After adjustment for patient and clinical characteristics, resistant hypertension was associated with a higher risk of cardiovascular events (hazard ratio, 1.47; 95% confidence interval, 1.33-1.62).

CONCLUSIONS

Among patients with incident hypertension in whom treatment was begun, 1 in 50 patients developed resistant hypertension. Patients with resistant hypertension had an increased risk of cardiovascular events, which supports the need for greater efforts toward improving hypertension outcomes in this population.

Lack of modulatory effect of simvastatin on indoxyl sulfate-induced activation of cultured endothelial cells

AIMS

Endothelial dysfunction is a common manifestation of chronic kidney disease (CKD). The protein-bound uremic toxins have emerged as important factors associated with cardiovascular disease and the outcome of CKD. The effect of indoxyl sulfate (IS) on endothelial cells remains unclear.

MAIN METHODS

Human umbilical endothelial cells (HUVEC) were incubated using IS at two concentrations: 100 μM and 1000 μM over two periods of time: 16 and 48 h. HUVEC were also pre-treated with simvastatin to examine its effect. RT-PCR was used to assess changes in the gene expression of intracellular cell adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), Monocyte chemotactic protein-1 (MCP-1), E-selectin, and angiotensin receptor type 1 (AT1R). Protein abundance of the investigated molecules was assessed by immunoblotting.

KEY FINDINGS

Treatment with 100 μM IS for 16 h induced a 2-fold increase in the expression of ICAM-1, VCAM-1, and MCP-1. At a concentration of 1000 μM, there was a 2-3-fold increase. An extended treatment period at low concentrations was associated with a 2-3 fold increase and the increase of ICAM-1 and VCAM-1 was more prominent under high concentration. Results of immunoblotting confirmed an increase in the abundance of ICAM-1, VCAM-1 and MCP-1. No significant change was noted in E-selectin and AT1R according to concentration or treatment duration. Pre-treatment with simvastatin did not alter IS-induced changes.

SIGNIFICANCE

IS increased the expression of adhesion molecules of endothelial cells exhibiting a concentration and duration dependent pattern. Simvastatin did not demonstrate any effect on IS-associated endothelial activation.

A renal transplant patient with abdominal discomfort, vomiting and diarrhoea for 1 week

The patient is a 61-year-old diabetic male with history of renal transplant who presented to the emergency department with complaints of intermittent abdominal discomfort accompanied by multiple episodes of vomiting and diarrhoea. He had delayed seeking medical attention until his friends insisted that he come to the emergency department, since the abdominal discomfort was worsening. The patient's ECG revealed an ST-segment elevation myocardial infarction.

Nitric oxide counters the inhibitory effects of uremic toxin indoxyl sulfate on endothelial cells by governing ERK MAP kinase and myosin light chain activation

Uremic toxins such as indoxyl sulfate (IS) accumulate at a high level in end stage renal disease (ESRD) and can exhibit significant systemic endothelial toxicity leading to accelerated cardiovascular events. The precise molecular mechanisms by which IS causes endothelial dysfunction are unknown. We tested the hypothesis that IS negatively influences properties of endothelial cells, such as migration and tube formation, by depleting nitric oxide (NO) bioavailability, and that an NO donor can reverse these inhibitory effects. IS inhibited human umbilical vein endothelial cell (HUVEC) migration and formation of tubes on matrigel. Mechanistically, IS inhibited VEGF-induced NO release from HUVECs. An NO donor, SNAP, reversed IS-mediated inhibition of HUVEC migration as well as tube-formation. IS inhibited ERK 1/2 MAP kinase activity in a dose-dependent manner, but this was preserved by SNAP. Inhibition of ERK 1/2 with a pharmacological inhibitor (U0126) decreased HUVEC migration and tube formation; these effects too were prevented by SNAP. Further, IS stimulated activation of myosin light chain (MLC), potentially stimulating endothelial contractility, while SNAP decreased MLC activation. Thus, we conclude that the negative effects of IS on endothelial cells are prevented, to a major extent, by NO, via its divergent actions on ERK MAP kinase and MLC.

Metabolic syndrome, chronic kidney disease, and cardiovascular disease: a dynamic and life-threatening triad

The metabolic syndrome (MS) and chronic kidney disease (CKD) have both become global public health problems, with increasing social and economic impact due to their high prevalence and remarkable impact on morbidity and mortality. The causality between MS and CKD, and its clinical implications, still does remain not completely understood. Moreover, prophylactic and therapeutic interventions do need to be properly investigated in this field. Herein, we critically review the existing clinical evidence that associates MS with renal disease and cardiovascular disease, as well as the associated pathophysiologic mechanisms and actual treatment options.

Cardiorenal risk factors

The chronic renocardiac syndrome, in which chronic kidney disease (CKD) contributes to impairment of cardiac function or structure, is associated with an increased risk of adverse cardiovascular events. The prevalence of CKD in the U.S. population is approximately 11% and has been increasing over time. Numerous studies have demonstrated an association of CKD, defined by the presence of reduced glomerular filtration rate and/or albuminuria with adverse cardiovascular and renal outcomes. These data suggest that both albuminuria and glomerular filtration rate, which can be performed with minimally increased costs, should be included in the assessment of risk stratification for individual patients, in addition to traditional cardiovascular risk factors.

Mechanisms of the cardiorenal syndromes

The kidney and heart have essential roles in maintaining blood volume homeostasis and in the regulation of systemic blood pressure. Acute or chronic dysfunction in either the heart or kidneys can induce dysfunction in the other organ, resulting in the so-called cardiorenal syndromes, which are classified into five different types. Abrupt worsening of cardiac function predisposes an individual to acute kidney injury from renal hypoperfusion or renal congestion. Progressive, sometimes permanent, chronic kidney impairment can result from chronic renal hypoperfusion or congestion. Heart failure is common in patients with acute kidney injury. Chronic kidney disease predisposes individuals to atherosclerotic, arteriosclerotic and cardiomyopathic disease. Finally, both cardiac and renal disease can also occur secondary to systemic conditions, such as diabetes or autoimmune disease. This Review examines the mechanisms presiding over the first four types of cardiorenal syndromes. These mechanisms provide a template that accounts for the heart-kidney interactions that occur in patients whose concomitant cardiac and renal conditions result from a third cause.

Cardiovascular implications of proteinuria: an indicator of chronic kidney disease

Proteinuria, defined as urine protein excretion greater than 300 mg over 24 h, is a strong and independent predictor of increased risk for all-cause and cardiovascular mortality in patients with and without diabetes. Proteinuria is a sign of persistent dysfunction of the glomerular barrier and often precedes any detectable decline in renal filtration function. Measurement of proteinuria is important in stratifying the risk for cardiovascular disease and chronic kidney disease progression. A variety of basic pathophysiologic mechanisms that can partially explain simultaneous renal and cardiac disease will be discussed in this Review. In addition to being a prognostic marker, proteinuria is being considered as a therapeutic target in cardiovascular medicine. Therapeutic strategies for amelioration of proteinuria by achieving blood pressure targets, glycemic control in diabetes, treatment of hyperlipidemia, and reducing dietary salt and protein intake are also reviewed in this paper. Future clinical studies are needed to assess if proteinuria reduction should be a target of treatment to reduce the burden of end-stage renal disease, cardiovascular disease, and improve survival in this high-risk population.