Secretory activity of the coronary artery endothelial cells in conditions of the peritoneal dialysis

Introduction

Endothelial dysfunction is frequent in patients treated with peritoneal dialysis and may lead to cardiac complications. We evaluated the effect of effluent dialysates and serum on the function of coronary artery endothelial cells (CAEC).

Methods

Human CAEC in in vitro culture were exposed to serum and dialysates from 24 patients treated with continuous ambulatory peritoneal dialysis (CAPD) and secretion of interleukin-6 (IL6), von Willebrand factor (vWF), tissue plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) were measured. Modulation of the secretory activity of CAEC by Sulodexide, mixture of glycosaminoglycans: heparin sulfate and dermatan sulfate, was studied.

Results

Serum from CAPD patients stimulated synthesis of IL6 (+93%), vWF (+18%), and PAI-1 (+20%) and did not change t-PA secretion in CAEC. Dialysates stimulated secretion of IL6 (+89%), vWF (+29%), and PAI-1 (+31%) and did not change t-PA synthesis. Dialysates collected in 12 patients after 6 months more strongly stimulated synthesis of IL6 (+37%) and PAI-1 (+7%). Sulodexide suppressed the secretory activity of CAEC stimulated by the studied sera: IL6 (–38%), vWF (–19%), t-PA (–13%), and PAI-1 (–12%).

Conclusions

Serum and the dialysate from CAPD patients induce inflammatory and prothrombotic reaction in coronary arterial endothelial cells. The general pattern of the observed effects for serum and dialysates was similar but the intensity of the effects was not identical. Sulodexide reduced these effects.

Role of Hypoalbuminemia in the Genesis of Cardiovascular Disease in Dialysis Patients

Our objective was to review the articles about the association between hypoalbuminemia and atherosclerotic or thrombotic cardiovascular disease (CVD) and to look for possible explanations for the role of hypoalbuminemia.

Increased incidences of CVD were reported in patients with hypoalbuminemia owing to renal or other diseases. Hypoalbuminemia increases plasma levels of lipoprotein(a), fibrinogen, and arachidonic acid metabolites; it also increases platelet aggregability and blood viscosity, all of which may contribute to the development of CVD. This cause-effect association is thought to be “dependent.” Changes in atherogenic lipoproteins or lipids, such as LDL cholesterol, triglycerides, and apolipoprotein B, are controversial in hypoalbuminemic dialysis patients, possibly because coexistent malnutrition and volume status can affect both albumin and lipids. In our recent study, there was a negative correlation between serum albumin and C-reactive protein, D-dimer (an index of intravascular thrombogenesis), and von Willebrand factor (a marker for endothelial cell injury), but infusion of albumin did not affect the level of these parameters, which suggests that the correlations may be an effect-effect association by a confounding variable, such as inflammation.

In conclusion, hypoalbuminemia is associated with cardiovascular disease via two pathways: one, a “dependent” cause-effect association; the other, an effect-effect association.

Major and Minor Risk Factors for Cardiovascular Disease in Continuous Ambulatory Peritoneal Dialysis Patients

Uremia in general and peritoneal dialysis in particular bring with them risk factors for the development of cardiovascular disease. These factors include multiple lipid abnormalities, hyperhomocysteinemia, abdominal obesity, chronic inflammation, hypoalbuminemia, oxidative stress, and AGE formation. When these are combined with conventional risk factors, one can appreciate why the incidence of cardiovascular disease is so high in peritoneal dialysis patients. Treatment strategies should address each of these risks appropriately.

Biocompatibility of New Peritoneal Dialysis Solutions: What Can We Hope to Achieve?

Despite the bioincompatibility of the “old”, standard, high glucose, lactate-buffered peritoneal dialysis (PD) solutions, PD is itself a highly successful dialysis modality with patient survival equivalent to that of hemodialysis (HD) during the initial 3 – 5 years of dialysis therapy. Nevertheless, PD technique survival is often limited by infectious complications and alterations in the structure and function of the peritoneal membrane. These local changes also have a negative impact on patient survival owing to systemic effects such as those often seen in patients with high peritoneal transport rate and loss of ultrafiltration (UF) capacity.

Patient mortality remains unacceptably high in both HD and PD patients, with most premature deaths being associated with signs of malnutrition, inflammation, and atherosclerotic cardiovascular disease (MIA syndrome). These systemic signs are likely to be influenced by PD solutions both directly and indirectly (via changes in the peritoneal membrane). New, biocompatible PD solutions may have favorable local effects (viability and function of the peritoneal membrane) and systemic effects (for example, on MIA syndrome). Amino acid–based solution [Nutrineal (N): Baxter Healthcare Corporation, Deerfield, IL, U.S.A.] may improve nutritional status as well as peritoneal membrane viability. Bicarbonate/lactate–buffered solution [Physioneal (P): Baxter Healthcare Corporation] may ameliorate local and systemic effects of low pH, high lactate, and high glucose degradation products. Icodextrin-based solution [Extraneal (E): Baxter Healthcare SA, Castlebar, Ireland] may improve hypertension and cardiovascular problems associated with fluid overload and may extend time on therapy in patients with loss of UF capacity.

The positive effects of each of these new, biocompatible solutions have been demonstrated in several studies. It is likely that the combined use of N, P, and E solutions will produce favorable synergies in regard to both local effects (peritoneal viability) and systemic effects (less malnutrition, inflammation, and fluid overload). Solution combination is an exciting area for clinical study in the coming years. Furthermore, dialysis fluid additives such as hyaluronan, which protects and improves the function of the peritoneal membrane, may further improve PD solutions. The new, biocompatible PD solutions represent an entirely new era in the evolution of the PD therapy; they are likely to have markedly positive effects on both PD technique and PD patient survival in coming years.

Prognostic value of fibrinogen-to-albumin ratio in predicting 1-year clinical progression in patients with non-ST elevation acute coronary syndrome undergoing percutaneous coronary intervention

Previous studies have indicated that fibrinogen and low serum albumin levels are associated with poor cardiovascular outcomes. The objective of the present study was to examine whether the fibrinogen-to-albumin ratio (FAR) was able to predict the 1-year prognosis of patients with non-ST elevation acute coronary syndrome (NSTE-ACS) following percutaneous coronary intervention (PCI). A total of 1,352 patients with NSTE-ACS undergoing PCI were included in this prospective study and were divided into a low-FAR group (FAR ≤8.713, n=901) and a high-FAR group (FAR>8.713, n=451). FAR was defined as the concentration ratio of fibrinogen (mg/dl) to albumin (mg/dl) multiplied by 100. The endpoint was the incidence of major adverse cardiovascular events (MACEs), including all-cause mortality, cardiac mortality, non-fatal myocardial reinfarction and unscheduled repeat revascularisation. The predictive performance was validated by receiver-operator characteristic (ROC) curve analysis. A total of 127 MACEs were noted during the 1-year follow-up period. Multivariate Cox analysis suggested that a high FAR was an independent predictor of all-cause mortality (hazard ratio=2.223, 95% confidence interval: 1.002-4.931, P=0.049). Regarding the predictor of MACEs, the FAR exhibited an area under the ROC curve of 0.676 with a sensitivity of 0.630 and a specificity of 0.726. The cut-off value was 9.114. The FAR was an independent prognostic factor in NSTE-ACS. The present results suggest that the FAR may serve as a potential prognostic indicator for patients with NSTE-ACS undergoing PCI (approval no. NCT02667548; January 29, 2016; Shengjing Hospital of China Medical University).

Plasminogen activator inhibitor-1 in kidney pathology (Review)

Plasminogen activator inhibitor type-1 (PAI-1) inhibits tissue plasminogen activator (tPA) and urokinase plasminogen activator (uPA), which convert plasminogen to plasmin, a strong proteolytic enzyme. Thus, PAI-1 is a primary and negative regulator of plasmin-driven proteolysis. In addition to its main role as an inhibitor of fibrinolysis, PAI‑1 has been implicated as a mediator in other processes, including fibrosis, rheumatoid arthritis, atherosclerosis, tumor angiogenesis and bacterial infections. It also significantly modulates cellular adhesion or migration, wound healing, angiogenesis and tumor cell metastasis. However, in the present study, we have reviewed the literature in relation to different kidney diseases where PAI-1 regulates fibrinolysis and acts independently of proteolysis. PAI-1 is normally produced in trace amounts in healthy kidneys but is synthesized in a wide variety of both acute and chronic diseased kidneys. We reviewed the role of PAI-1 in diabetic kidney nephropathy, chronic kidney disease, hemodialysis, peritoneal dialysis and in kidney transplantation. Increased PAI-1 expression results in accumulation of extracellular matrix (ECM) leading to numerous kidney diseases. Predisposition to some diseases is due to the genetic role of PAI-1 in their development. A number of studies demonstrated that the inhibition of PAI-1 activity or therapy with a mutant PAI-1 increases matrix turnover and reduces glomerulosclerosis by competing with endogenous PAI-1. This strongly suggests that PAI-1 is a valid target in the treatment of fibrotic renal disease. However, net proteolytic activity depends on the delicate balance between its negative regulation by PAI-1 and activation by uPA and tPA. Also, plasmin activated by its inhibitors upregulates activity of other enzymes. Thus, assessment of prognosis for the diseased kidney should include a variety of proteolysis regulators and enzymes.

Molecular pathways and crosstalk characterizing the cardiorenal syndrome

The risk of developing cardiovascular diseases (CVD) is dramatically increased in patients with chronic kidney diseases (CKD). Mechanisms leading to this cardiorenal syndrome (CRS) are multifactorial, and combined analyses of both failing organs may provide routes toward developing strategies for early risk assessment, prognosis, and consequently effective therapy. In order to identify molecular mechanisms involved in the crosstalk between the diseased cardiovascular system and kidney, we analyzed tissue specific transcriptomics profiles on atherosclerosis and diabetic nephropathy together with gene sets associated with cardiovascular and chronic kidney diseases that derived from a literature mining approach. We focused on enriched molecular pathways and highlight molecular interactions found within as well as between affected pathways identified for the two organs. Analysis on the level of molecular pathways pointed out the role of PPAR signaling, coagulation, inflammation, and focal adhesion pathways in formation and progression of the CRS. The proteins apolipoprotein A1 (APOA1) and albumin (ALB) turned out to be of particular importance in the context of dyslipidemia, one of the major risk factors for the development of CVD. In summary, our analyses highlight mechanisms associated with dyslipidemia, hemodynamic regulation, and inflammation on the interface between the cardiovascular and the renal system.

Acute phase reactants as novel predictors of cardiovascular disease

Acute phase reaction is a systemic response which usually follows a physiological condition that takes place in the beginning of an inflammatory process. This physiological change usually lasts 1-2 days. However, the systemic acute phase response usually lasts longer. The aim of this systemic response is to restore homeostasis. These events are accompanied by upregulation of some proteins (positive acute phase reactants) and downregulation of others (negative acute phase reactants) during inflammatory reactions. Cardiovascular diseases are accompanied by the elevation of several positive acute phase reactants such as C-reactive protein (CRP), serum amyloid A (SAA), fibrinogen, white blood cell count, secretory nonpancreatic phospholipase 2-II (sPLA2-II), ferritin, and ceruloplasmin. Cardiovascular disease is also accompanied by the reduction of negative acute phase reactants such as albumin, transferrin, transthyretin, retinol-binding protein, antithrombin, and transcortin. In this paper, we will be discussing the biological activity and diagnostic and prognostic values of acute phase reactants with cardiovascular importance. The potential therapeutic targets of these reactants will be also discussed.

Bioactivity of beer and its influence on human metabolism

Extracted total phenols, flavanols and flavonoids were measured in beer samples and their quality as antioxidants was measured by two modified antioxidant methods: the 2,2'-azinobis (3-ethylbenzothiazoline-6-sulfonate) radical cation (ABTS * +) and the beta-carotene-linoleate model system (beta-carotene). It was found that the antioxidant potential of beer was well correlated with flavanols and flavonoids and was slightly lower with total polyphenols (R2 values from 0.8203 to 0.9393). Forty-two male non drinkers, hypercholesterolaemic volunteers ages 43-71 after coronary bypass surgery, were randomly divided into experimental (EG) and control (CG) groups, each of 21 participants. The antiatherosclerotic diet of the EG group was supplemented for 30 consecutive days with 330 ml beer per day. Could short-term beer consumption affect not only the risk factors of coronary atherosclerosis, but also the markers of this process: plasma albumin and its antioxidant activity? For this goal, total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, triglycerides, plasma albumin and fibrinogen, and the antioxidant activity were determined. After the trial a significant improvement in the plasma lipid levels, and an increase in the plasma antioxidant and anticoagulant activities in patients of the EG group was registered. A parallel increase in the plasma albumin concentration and its antioxidant activity was observed. In conclusion, short-term beer consumption on the basis of the bioactivity of the beverage positively affects plasma lipid levels, plasma antioxidant and anticoagulant activities. The increase in the plasma albumin concentration and its antioxidant activity could be the markers of atherosclerosis status.

Global fibrinolytic capacity in children on dialysis

Disturbances of coagulation and fibrinolysis have been reported in patients with chronic uremia. Studies of different coagulation and fibrinolysis parameters in regularly dialyzed patients have yielded conflicting results. Global fibrinolytic capacity (GFC) examines the function of the entire fibrinolytic system. This assay is a sensitive and reliable method for evaluating the fibrinolytic function of plasma in vitro. In this study, GFC was used as a screening test to investigate the effects of two different dialysis modalities on the fibrinolytic system on children on long-term dialysis.

MATERIALS AND METHODS

The study included 12 children (age range, 11-20 years; mean age, 15.9+/-3.3 years) who were undergoing regular hemodialysis (HD) and 12 children (age range, 10-15 years; mean age, 13.1+/-1.7 years) who were undergoing continuous ambulatory peritoneal dialysis (CAPD). Thirteen healthy age- and sex-matched subjects served as controls. Each sample was investigated for complete blood count and serum levels of C-reactive protein, serum electrolytes, total cholesterol, triglyceride, fibrinogen, total protein and albumin. A GFC assay was also done in each case.

RESULTS

The mean GFC in the CAPD group was lower than that in the HD and control groups (p<0.05). There was no significant difference between the mean GFC values of HD patients and controls. The mean serum albumin level was lower in CAPD patients than in HD patients (p<0.05), and there was also a positive correlation between serum albumin level and GFC in patient groups(r=0.52, p<0.05). Global fibrinolytic capacity was positively correlated with hemoglobin level and negatively correlated with weekly erythropoietin dose per kg body weight (r=0.56 and r=-0.49, respectively; p<0.05).

CONCLUSION

The results suggest that CAPD patients have decreased fibrinolytic capacity compared to HD patients. Hypoalbuminemia and erythropoietin treatment may contribute to suppression of fibrinolytic function CAPD patients.

Prevalence of coronary artery disease using thallium-201 single photon emission computed tomography among patients newly undergoing chronic peritoneal dialysis and its association with mortality

BACKGROUND

Previous data about the prevalence of coronary artery disease in dialysis patients were mainly based on history or electrocardiogram.

METHODS

We evaluated the prevalence of coronary artery disease using routine thallium-201 single photon emission computed tomography (SPECT) in 227 patients at the start of chronic peritoneal dialysis between January 1996 and October 2003. We also analyzed its association with mortality.

RESULTS

Fifty-one patients (22.5%) were positive on thallium SPECT. There were significant differences in age, underlying diabetic nephropathy, and C-reactive protein (CRP), serum albumin, total cholesterol, and prealbumin levels among patients positive and negative on thallium SPECT. Multivariate logistic regression analysis showed that age (> or =60 years), underlying diabetic nephropathy, and CRP (> or =0.5 mg/dl) were independent predictors of positive thallium SPECT, with the patients positive for all three factors having a probability for positive thallium SPECT of 43%, whereas patients negative for all three factors had a probability of only 4%. Ninety patients died, and 137 survived during the median follow-up period of 34 (range 3-99) months. Kaplan-Meier survival analysis revealed that age, underlying diabetic nephropathy, serum albumin, prealbumin, and CRP levels, positive thallium SPECT, and smoking affected survival. Survival was not different according to gender, presence of hypertension, body mass index, total cholesterol, or lipoprotein(a). Cox regression analysis showed that only underlying diabetic nephropathy and age (> or =60 years) were independent predictors of mortality.

CONCLUSIONS

We found that 22.5% of the patients who started chronic peritoneal dialysis had a positive thallium SPECT. Age, underlying diabetic nephropathy, and CRP were independent predictors of a positive thallium SPECT. Underlying diabetic nephropathy and age, but not positive thallium SPECT, were independent predictors of mortality.

Pathogenic effects of a high peritoneal transport rate

Recent studies have shown that patients with high peritoneal transport characteristics have substantially increased morbidity and mortality. This finding is counter-intuitive, since HTs will a priori achieve higher clearances. There are many possible causes: increased protein losses with consequent hypoalbuminemia; poor ultrafiltration capacity causing fluid retention, ventricular hypertrophy and hypertension; increased glucose absorption leading to anorexia, hyperinsulinism, and local AGE formation; and the development of an atherogenic lipid profile. While common pathogenic causes of high peritoneal transport and atherosclerosis have been hypothesized, it is more likely that CAPD as currently practiced is unsuitable for HTs, who should be switched to HD or NIPD. Renal and peritoneal clearances have different clinical effects and should be assessed separately. Current measures of dialysis adequacy, such as total Kt/V, do not therefore describe the patient's clinical situation accurately and are insufficient.

Homocysteine, lipoprotein(a) and fibrinogen: metabolic risk factors for cardiovascular complications of chronic renal disease

High plasma concentrations of homocysteine, lipoprotein(a) and fibrinogen are accompanied by an increased risk for cardiovascular complications in the general population. All three parameters are markedly elevated in patients with renal disease, a group with a high prevalence and incidence of cardiovascular complications. This review discusses these parameters in such patients in relation to the occurrence of atherosclerotic complications.