Expression of apolipoprotein B epitopes in low density lipoproteins of hemodialyzed patients

Lipoprotein metabolism in chronic renal insufficiency

Chronic renal insufficiency (CRI) is associated with a characteristic dyslipidemia. Findings in children with CRI largely parallel those in adults. Moderate hypertriglyceridemia, increased triglyceride-rich lipoproteins (TRL) and reduced high-density lipoproteins (HDL) are the most usual findings, whereas total and low-density lipoprotein cholesterol (LDL-C) remain normal or modestly increased. Qualitative abnormalities in lipoproteins are common, including small dense LDL, oxidized LDL, and cholesterol-enriched TRL. Measures of lipoprotein lipase and hepatic lipase activity are reduced, and concentrations of apolipoprotein C-III are markedly elevated. Still an active area of research, major pathophysiological mechanisms leading to the dyslipidemia of CRI include insulin resistance and nonnephrotic proteinuria. Sources of variability in the severity of this dyslipidemia include the degree of renal impairment and the modality of dialysis. The benefits of maintaining normal body weight and physical activity extend to those with CRI. In addition to multiple hypolipidemic pharmaceuticals, fish oils are also effective as a triglyceride-lowering agent, and the phosphorous binding agent sevelamer also lowers LDL-C. Emerging classes of hypolipidemic agents and drugs affecting sensitivity to insulin may impact future treatment. Unfortunately, cardiovascular benefit has not been convincingly demonstrated by any trial designed to study adults or children with renal disease. Therefore, it is not possible at this time to endorse general recommendations for the use of any agent to treat dyslipidemia in children with chronic kidney disease.

Effect of spironolactone on cisplatin-induced nephrotoxicity in rabbits

The effects of a single interaperitoneal dose of cisplatin (6.5 mg kg day(-1)), oral doses of spironolactone (20.0 mg kg day(-1)) for 5 days or the combined treatment (spironolactone+cisplatin) on the kidney function and liver function parameters, as well as the serum, liver and kidney cortical lipid contents were studied. The serum urea and creatinine concentrations (measured as kidney function parameters) were not altered by spironolactone treatment, but were significantly (P<0.001) elevated by cisplatin administration. However, animals exposed to both spironolactone+cisplatin revealed drastic increases in the serum creatinine and urea concentrations amounting to about four- and twofold those of cisplatin-alone treated animals, respectively. The histological examination of slides of kidneys from animals exposed to the combined drugs exhibited more extensive necrosis in the tubules compared to those from animals treated with cisplatin alone. Non of the drug treatments had any effects on the serum alanine transaminase (ALT) and aspartate transaminase (AST) levels (measured as liver function parameters) or liver protein content or hepatic alkaline phosphatase (ALP) activity. The histological examination also revealed apparently normal livers in all experimental groups. The cisplatin-induced nephrotoxicity was accompanied by hypercholesterolaemia and hyperphospholipidaemia, whereas spironolactone showed a hypocholesterolaemic effect. The concomitant treatment with both cisplatin and spironolactone significantly (P<0.05) raised the serum triacylglycerol (TAG) concentration compared to the cisplatin-alone-treated group. Both spironolactone and cisplatin administered separately or jointly caused accumulation of cholesterol and TAG in the kidney cortex with significant depletion of the liver cholesterol content. The present results indicated that spironolactone aggravates the cisplatin-induced nephrotoxicity in the rabbit.

Hyperlipidaemia in cisplatin-induced nephrotic rats

The serum and hepatic lipid concentrations were investigated in rats made nephrotic with a single intraperitoneal injection of cisplatin (6 mg kg(-1) b.wt.). The serum creatinine and urea concentrations were estimated as indices of nephrotoxicity, and the serum total bilirubin level as a liver function test. 3 The fasting serum total cholesterol, triglycerides (TG) and the cholesterol fractions associated with the various lipoproteins, as well as hepatic cholesterol and TG contents were also measured, following 5, 10 and 15 days from the cisplatin treatment. 4 The results revealed that on day 5 both serum creatinine and urea concentrations were significantly (P<0.01) increased, indicating the peak of nephrotoxicity, with no injurious effects on the liver as indicated by the unaltered serum bilirubin concentration. 5 The nephrotoxicity was accompanied by significant elevations in serum total cholesterol and TG concentrations by 49 and 42%, respectively, with significant (P < 0.05) correlations between the serum cholesterol and TG concentrations versus the serum urea (r=0.68 and r=0.60, respectively). Among the estimated lipoproteins, very low density lipoprotein (VLDL) cholesterol was severely increased to more than twofold with no severe changes in LDL- or HDL-cholesterol fractions. On day 5 the liver also showed significant accumulation of TG with no change in the cholesterol content. Animals killed 10 or 15 days post-cisplatin treatment had all the perturbed parameters returned to the normal levels. The present results indicated that rats exposed to a single cisplatin injection exhibit acute reversible nephrosis on day 5 which was accompanied by dyslipidaemia and accumulated liver TG.

Reduction of plasma apolipoprotein-B by effective removal of circulating glycation derivatives in uremia

Patients with diabetes and renal insufficiency (Db/ESRD), a group subject to accelerated atherosclerosis exhibit marked increases in the levels of circulating, glycation-derived reactive substances, termed advanced glycation endoproducts (AGEs). These products have been previously shown to react covalently with apoliprotein B (ApoB) to form AGE-ApoB, a modification that results in delayed low density lipoprotein (LDL) clearance and possibly to dyslipidemia. Because the effect of hemodialysis on AGE removal was shown to be unsatisfactory, based on single intradialytic studies, we examined the effect of long-term hemodialysis therapy on serum AGE-ApoB levels, as well as on total serum ApoB of 25 Db/ESRD patients treated by two types of hemodialysis filters, the Fresenius Inc. F8, as the low flux (LF), or high-flux polysulfone AN69 (HF) for two months using an AGE-specific ELISA. At the end of eight weeks, circulating AGE-ApoB levels were reduced significantly (by 35%) from baseline (P = 0.039) in patients treated by HF compared to a modest 16% reduction noted in patients treated by LF (P = 0.05) N = 12, P = 0.047). Of note, total plasma ApoB was reduced by 27% from baseline (P = 0.02) in patients treated by HF compared to a 6% reduction noted in those treated with LF (P = 0.8). In vitro comparison of AGE mass balance, and mass adsorption by the different filters revealed that the higher efficiency of HF filter was due to greater adsorption. The association of reduced AGE-ApoB levels with a decrease in total circulating ApoB by HF and not by LF dialysis suggests: (1) a causal link between AGE clearance and dyslipidemia in diabetic ESRD, and, (2) that more efficient modes of renal replacement treatment and AGE removal could significantly benefit clinical outcome.

Cardiac disease in chronic uremia: pathogenesis

Cardiomyopathy in chronic uremia results from pressure and volume overload. The former causes concentric left ventricular [LV] hypertrophy, results from hypertension and aortic stenosis, and is also associated with diabetes mellitus and anemia. Volume overload causes LV dilatation, results from arteriovenous shunting, salt and water overload, and anemia, and is also associated with ischemic heart disease, hypertension, and hypoalbuminemia. Decreased major arterial compliance and an early return of arterial wave reflections are also associated with the extent of LV hypertrophy. Cardiomyopathy predisposes to diastolic and systolic dysfunction. The latter results from myocyte death, and predisposing factors include ischemic heart disease and the uremic environment. Ischemic heart disease may be atherosclerotic or nonatherosclerotic in origin. Multiple factors contribute to the vascular pathology of chronic uremia, including injury to the vessel wall, dyslipidemia, prothrombotic factors, increased oxidant stress, and hyperhomocysteinemia. Ischemic risk factors include hypertension, LV hypertrophy, hypoalbuminemia, and perhaps hyperparathyroidism. The clinical consequences of cardiomyopathy include heart failure, ischemic heart disease, dialysis hypotension, and arrhythmias. The adverse impact of ischemic heart disease is probably mediated through the development of cardiac failure.

Cardiac disease in chronic uremia: clinical outcome and risk factors

Cardiac disease is common and is the major killer in end-stage renal disease (ESRD). Cardiac failure is a highly malignant condition in ESRD patients. Cardiac failure mediates most of the adverse prognostic impact of ischemic heart disease. Left ventricular (LV) abnormalities are already present at initiation of dialysis therapy in approximately 80% of patients. These abnormalities (ie, systolic dysfunction in approximately 15%, LV dilatation with preserved systolic function in 30%, concentric LV hypertrophy [LVH] in 40%) independently predict ischemic heart disease and cardiac failure, and are the largest baseline predictor of mortality after 2 years on dialysis therapy. The associations between classical risk factors (eg, hyperlipidemia, smoking, hypertension) and cardiac outcomes in ESRD are inconsistent. "Uremic" risk factors represent a nascent, but potentially important field. In our prospective 10-year study of 433 patients starting renal replacement therapy, we identified the following as major independent risk factors for cardiac disease: (1) hypertension (concentric LVH, LV dilatation, ischemic heart disease, cardiac failure, inverse relationship with mortality); (2) anemia (LV dilatation, cardiac failure, death); and (3) hypoalbuminemia (ischemic heart disease, cardiac failure, death). Transplantation dramatically improved LV abnormalities, suggesting that a uremic environment is cardiotoxic. Multiple risk factors act in concert to produce cardiac disease in ESRD; many of these are avoidable, suggesting that the enormous burden of disease can be reduced considerably.

Fluvastatin (Lescol) treatment of hyperlipidaemia in patients with renal transplants

Hyperlipidaemia of 18 male and 20 female patients following successful renal transplantation was treated with daily 20 mg fluvastatin (Lescol) for 12 weeks. The patients were several months after transplantation, and their total cholesterol levels exceeded 6.5 mmol/l following an 8-week diet. The effect of fluvastatin on the levels of total cholesterol, HDL, LDL, triglyceride, Apo A1 and Apo B, as well as of lipoprotein(a) was examined. Furthermore, changes of the renal function (GFR-urea, creatinine, uric acid) and hepatic function (bilirubin, GOT, GPT, CPK, ALP) were followed up, together with the body weight and blood pressure. The results of the examinations are summarized as follows: Fluvastatin may be administered effectively and without side effects in a daily dose of 20 mg in appropriately selected renal transplant patients. The average total cholesterol values, which were 7.91 mmol/l in men and 7.78 mmol/l in women following the diet, were reduced by 22-25% (p < 0.001) after 6 and 12 weeks, respectively, of fluvastatin treatment. The levels of LDL also decreased significantly (p < 0.001): in response to a 20 mg evening dosage, reduction of more than 25% was observed in 78% of men and 65% of women. Reductions of the Apo B levels were more pronounced in the females (18.3% men vs. 21.2% women). The ratio C/HDL-C decreased both in men (from 5.49 to 4.19) and in women (from 4.83 to 4.02). The ratio Apo B/Apo A1 also decreased (men: from 0.86 to 0.73, women: from 0.73 to 0.66). The concentrations of HDL and Apo A1 did not increase significantly, the reductions in the levels of triglyceride and lipoprotein(a) were not considerable either. An increase in the levels of hepatic enzymes and CPK was not encountered during the administration of fluvastatin. In two patients the levels of serum bilirubin increased by 2-4 micromol/l. Three patients complained about temporary myalgias of the sacroiliac or lumbar region which, however, were not accompanied by elevated CPK levels. The monitored levels of cyclosporine, urea and creatinine did not increase significantly during the 12 weeks of treatment. Two patients had temporary gastric complaints.

Outcome and risk factors of ischemic heart disease in chronic uremia

To determine the prognosis and risk factors for ischemic heart disease in chronic uremia, a cohort of 432 dialysis patients were followed prospectively from start of dialysis therapy until death or renal transplantation. Baseline demographic, clinical and echocardiographic data were obtained. After the initiation of dialysis laboratory data were collected at monthly intervals, and clinical and echocardiographic data at yearly intervals. Twenty-two percent of patients (N = 95) had either a history of angina pectoris or myocardial infarction on starting dialysis therapy. Median time to onset of heart failure was 24 months in those with ischemic heart disease on initiation of dialysis, compared to 55 months in those without (P < 0.0001). This effect was independent of age, diabetes and underlying cardiomyopathy. Median survival was 44 months in those with ischemic disease compared to 56 months in those without (P = 0.0001). This adverse impact was independent of age and diabetes mellitus but, when cardiac failure was added to the Cox's model, ischemic heart disease was no longer an independent predictor of survival. De novo ischemic heart disease, not evident on starting dialysis therapy, occurred in 41 (9%) patients. When compared to patients who never developed ischemic disease (N = 296; 69%), significant and independent predictors of de novo disease were older age (P = 0.0007), diabetes mellitus (P = 0.0001), high blood pressure during follow up on dialysis (P = 0.02) and hypoalbuminemia (P = 0.03), whereas anemia was not an independent predictor. LV mass index was 174 +/- 7 g/m2 in those who developed de novo ischemic disease compared to 155 +/- 3 g/m2 (P < 0.001) in those who did not. Concentric LV hypertrophy, LV dilation and systolic dysfunction were independent risk factors for de novo ischemic heart disease. We conclude that ischemic heart disease occurs frequently in dialysis patients, that its adverse impact is mediated through the development of heart failure, and that the most important, potentially reversible risk factors are hypertension, hypoalbuminemia, and underlying cardiomyopathy.