The effects of lovastatin in hyperlipidemic patients with the nephrotic syndrome

Current state and future perspective of cardiovascular medicines derived from natural products

The contribution of natural products (NPs) to cardiovascular medicine has been extensively documented, and many have been used for centuries. Cardiovascular disease (CVD) is the leading cause of morbidity and mortality worldwide. Over the past 40 years, approximately 50% of newly developed cardiovascular drugs were based on NPs, suggesting that NPs provide essential skeletal structures for the discovery of novel medicines. After a period of lower productivity since the 1990s, NPs have recently regained scientific and commercial attention, leveraging the wealth of knowledge provided by multi-omics, combinatorial biosynthesis, synthetic biology, integrative pharmacology, analytical and computational technologies. In addition, as a crucial part of complementary and alternative medicine, Traditional Chinese Medicine has increasingly drawn attention as an important source of NPs for cardiovascular drug discovery. Given their structural diversity and biological activity NPs are one of the most valuable sources of drugs and drug leads. In this review, we briefly described the characteristics and classification of NPs in CVDs. Then, we provide an up to date summary on the therapeutic potential and the underlying mechanisms of action of NPs in CVDs, and the current view and future prospect of developing safer and more effective cardiovascular drugs based on NPs.

Protective role of γ-aminobutyric acid against chronic renal failure in rats

The protective effect of γ-aminobutyric acid (GABA) against chronic renal failure (CRF) was investigated using a remnant kidney model with 5/6 nephrectomized rats. Nephrectomy led to renal dysfunction, which was evaluated via several parameters including serum urea nitrogen, creatinine (Cr) and Cr clearance. However, the administration of GABA ameliorated renal dysfunction, and a longer administration period of GABA increased its protective effect. In addition, nephrectomized control rats showed an elevation in the fractional excretion of sodium (FENa) with an increase in urinary sodium, while GABA led to a significant decline in FENa. Moreover, nephrectomy resulted in a decrease of serum albumin and an increase of urinary protein with a change in the urinary protein pattern, whereas the rats administered GABA showed improvement in these changes associated with CRF caused by nephrectomy. This suggests that GABA would inhibit the disease progression and have a protective role against CRF. As one of the risk factors for CRF progression, hypertension was also regulated by GABA. The results also indicate that GABA may play a protective role against CRF through improvement of the serum lipid profile, with reductions in triglyceride and total cholesterol. Furthermore, nephrectomy led to renal oxidative stress with a decrease in the activity of antioxidative enzymes and elevation of lipid peroxidation. The administration of GABA attenuated oxidative stress induced by nephrectomy through an increase in superoxide dismutase and catalase, and decrease in lipid peroxidation. The histopathological lesions, including glomerular, tubular and interstitial lesions, under nephrectomy were also improved by GABA with the inhibition of fibronectin expression. This study demonstrated that GABA attenuated renal dysfunction via regulation of blood pressure and lipid profile, and it also ameliorated the oxidative stress induced by nephrectomy, suggesting the promising potential of GABA in protecting against renal failure progression.

Membranous nephropathy in the older adult: epidemiology, diagnosis and management

Membranous nephropathy is the most important cause of the nephrotic syndrome in elderly patients (aged >65 years). The clinical presentation is similar in older and younger patients, although elderly patients more often present with renal failure. Notably, glomerular filtration rate (GFR) is usually lower in the elderly due to the physiological decline in GFR after the age of 30 years. Secondary causes, especially malignancies, are more common in older patients with membranous nephropathy. Therefore, elderly patients should undergo a thorough examination to exclude a secondary cause. The prognosis of elderly patients with idiopathic membranous nephropathy is not very different from that of younger patients. All elderly patients should receive symptomatic treatment aimed at reducing hypertension, oedema, proteinuria and hyperlipidaemia. It is recommended that elderly patients with a low serum albumin (<2 g/dL) receive prophylactic anticoagulation because of a high risk for thrombosis. Immunosuppressive therapy should be reserved for elderly patients at high risk of progression to end-stage renal disease because the elderly are particularly prone to the adverse effects and infectious complications of immunosuppressive therapy. High-risk elderly patients are characterised by renal insufficiency (GFR <45 mL/min/1.73m(2)), an increase in serum creatinine of >25% or a severe persistent nephrotic syndrome not responding to symptomatic treatment. In addition, elderly patients with a relatively normal GFR (>or=45 mL/min/1.73m(2)) and high urinary excretion of beta(2)-microglobulin and IgG are also at increased risk of developing end-stage renal disease; however, the deterioration in renal function is usually a slow process. Therefore, such patients benefit from immunosuppressive therapy only if their life expectancy is good. If immunosuppressive therapy is started, first-line treatment consists of prednisone and cyclophosphamide. If cyclophosphamide is contraindicated or fails to induce a remission, ciclosporin could be used. Treatment with ciclosporin should be limited to patients with a relatively normal renal function (GFR >60 mL/min/1.73m(2)) in view of its nephrotoxicity in patients with renal dysfunction.

Long-term efficacy of low-density lipoprotein apheresis for focal and segmental glomerulosclerosis

Recently, there have been reports on the efficacy of low-density lipoprotein (LDL) apheresis (LDL-A) for focal and segmental glomerulosclerosis (FSGS) in pediatric patients. However, there have been few reports on the long-term efficacy of LDL-A for FSGS in such patients. We report here a case of long-term efficacy of LDL-A for FSGS. The patient was a 13-year-old boy with FSGS who presented with steroid-resistant and cyclosporine-resistant nephrotic syndrome and hyperlipidemia. LDL-A was performed 24 times on one year. Following LDL-A, serum concentrations of LDL, very low-density lipoprotein (VLDL), apoprotein B, and vascular endothelial growth factor significantly decreased, and urinary excretion of protein also decreased. In addition, 3 years after LDL-A, the pathology findings on a second renal biopsy had improved. The patient has been in remission from FSGS for 12 years since LDL-A. These findings suggest that LDL-A may be useful in maintaining long-term remission from pediatric FSGS.

Membranous lupus nephritis

Membranous lupus nephritis (MLN) represents about 20% of clinically significant renal disease in lupus. Few studies have addressed directly the pathogenesis of MLN. Our assumptions about the underlying mechanisms are based on the combination of extrapolations from idiopathic membranous nephritis (mainly from animal models) and proliferative lupus nephritis. Natural history studies of MLN suggest a relatively low rate of progression to end-stage renal disease but a high rate of significant comorbidities. Historical changes in the criteria for pathologic diagnosis and classification of membranous lupus nephropathy have precluded definitive descriptions of the natural history, prognosis and treatment of this disorder. Patients with membranous lupus nephropathy should be treated early with angiotensin antagonists to minimize proteinuria, as well as lifestyle changes and appropriate drugs to reduce attendant cardiovascular risk factors. In patients with protracted nephrotic syndrome, consideration should be given to immunosuppressive therapies, including corticosteroids, cyclosporine, mycophenolate and cyclophosphamide. Prospective controlled trials are clearly needed in order to establish solid clinical practice guidelines for use of these drugs and other experimental therapies currently under study in membranous lupus nephropathy.

The Potential Role of HMG-CoA Reductase Inhibitors in Pediatric Nephrotic Syndrome

OBJECTIVE

To evaluate the safety and efficacy of the hydroxymethylglutaryl coenzyme A (HMG-CoA) reductase inhibitors (statins) as a potential treatment option for the dyslipidemia associated with childhood nephrotic syndrome.

DATA SOURCES

Searches of MEDLINE (1966–April 2004), Cochrane Library, International Pharmaceutical Abstracts (1977–April 2004), and an extensive manual review of journals were performed using the key search terms nephrotic syndrome, familial hypercholesterolemia, dyslipidemia, and HMG-CoA reductase inhibitor.

STUDY SELECTION AND DATA EXTRACTION

Two prospective uncontrolled studies evaluating the safety and efficacy of statin therapy in pediatric nephrotic syndrome were included.

DATA SYNTHESIS

While an extensive amount of data is available in adult nephrotic syndrome in which statin therapy decreases total plasma cholesterol 22–39%, low-density lipoprotein cholesterol (LDL-C) 27–47%, and total plasma triglycerides 13–38%, only 2 small uncontrolled studies have been conducted evaluating the utility of these agents in pediatric nephrotic syndrome. These studies indicate that statins are capable of safely reducing total cholesterol up to 42%, LDL-C up to 46%, and triglyceride levels up to 44%.

CONCLUSIONS

Lowering cholesterol levels during childhood may reduce the risk for atherosclerotic changes and may thus be of benefit in certain patients with nephrotic syndrome. Statins have demonstrated short-term safety and efficacy in the pediatric nephrotic syndrome population. Implementing pharmacologic therapy with statins in children with nephrotic syndrome must be done with care until controlled studies are conducted in this population.

Other immunosuppressive agents for focal segmental glomerulosclerosis

A prolonged course with corticosteroids represents the first therapeutic approach for nephrotic patients with focal segmental glomerulosclerosis (FSGS). In patients with contraindications to steroids or in those who do not respond to steroids or cyclosporine, cytotoxic agents, mycophenolate mofetil (MMF), plasmapheresis, and low-density lipoprotein (LDL) apheresis have been tried as alternative treatments. A short-term treatment with cytotoxic agents often is ineffective in steroid-resistant patients However, an aggressive and prolonged treatment with cytotoxic agents combined with corticosteroids proved to be effective in more than half of steroid-resistant children. In adults, the response to cytotoxic agents was good in steroid-responsive patients, but was poor in steroid-resistant patients. Better results were observed when cytotoxic therapy was prolonged for several months. The problem with these drugs is that long-term immunosuppression may be complicated by severe side effects including a major risk for cancer. Uncontrolled studies reported that MMF can induce some reduction of proteinuria, but complete remission of proteinuria was rare and no data on long-term follow-up evaluation with this drug are available. Good results have been reported with plasmapheresis, immunoadsorption, and lipopheresis. However, all the reports were uncontrolled, small sized, and with short-term follow-up evaluation. In conclusion, there are several therapeutic options for patients who respond to steroids and have further relapses of nephrotic syndrome, but how to treat steroid-resistant patients is still a matter of debate. Nevertheless, a 6-month trial with cytotoxic agents or MMF can be offered to steroid-resistant patients to identify the few patients who respond to these agents. The preliminary results with plasmapheresis or lipopheresis are promising but further studies are needed to assess the role of these treatments.

The effect of pravastatin on renal function and lipid metabolism in patients with renal dysfunction with hypertension and hyperlipidemia. Pravastatin and Renal Function Research Group

The effect of pravastatin on renal function in hypertensive patients with mild renal dysfunction and hyperlipidemia was examined. A total of 57 subjects given dihydropyridine calcium blockers were randomly assigned to placebo (n = 25) and pravastatin groups (n = 32). The period of study was 6 months. In the placebo group, lipid metabolism did not change throughout the study period, but the serum creatinine concentration (Scr) increased from a baseline of 1.6+/-0.07 mg/dl to 2.1+/-0.2 mg/dl in the 6th month of study and blood urea nitrogen (BUN) increased from 26.2+/-1.1 mg/dl to 32.4+/-30.1 mg/dl. In the pravastatin group, the serum total cholesterol decreased from a baseline of 251.4+/-7.3 mg/dl to 218.2+/-6.5 mg/dl in the 6th month of study, while Scr (1.3+/-0.07 mg/dl vs. 1.3 +/-0.09 mg/dl) and BNU (20.5+/-1.2 mg/dl vs. 21.0+/-1.4 mg/dl) did not change. The change in Scr in the placebo group was significantly different from that in the pravastatin group (F = 3.75, p = 0.05). The slope of the change in 1/Scr was 0.02+/-0.07 dl x mg(-1) x month(-1) in placebo group and -0.01+/-0.03 dl x mg(-1) month(-1) in pravastatin group (P<0.05). The results indicate that pravastatin attenuates the deterioration of renal function in patients with mild renal dysfunction, together with an improvement of lipid metabolism.

Low density lipoprotein apheresis therapy for steroid-resistant nephrotic syndrome. Kansai-FGS-Apheresis Treatment (K-FLAT) Study Group

BACKGROUND

The pathogenic role of hyperlipidemia in long-standing nephrotic syndrome (NS) is known to be responsible for both the progression of glomerulosclerosis and tubulointerstitial injury, especially in focal segmental glomerulosclerosis (FGS).

METHODS

Aggressive lipid lowering treatment by low density lipoprotein (LDL) apheresis (LDL-A) using a dextran sulfate cellulose column to treat patients with steroid-resistant or frequently recurrent severe NS was performed first without fixing the protocol in eight patients with FGS and one with minimal change nephrotic syndrome (MCNS). The period of NS before LDL-A, number and average intervals of LDL-A until the end of the therapy, and the prognosis were investigated. Next, a multicenter study with a fixed protocol of LDL-A treatment was designed in combination with steroid therapy for treatment twice a week for three weeks and weekly for six weeks, and was performed in 17 patients with FGS. The effects on the state of NS in addition to the change of urinary eicosanoid metabolites and remission rates were evaluated.

RESULTS

In the preliminary study, along with a rapid improvement of hyperlipidemia, a high incidence of remission was achieved by LDL-A performed at relatively short intervals. In the multicenter study with a fixed protocol, there was a significant decrease of urinary protein (P < 0.001) and increase of serum albumin (P < 0.02) as well as a decrease of thromboxane B2 (TXB2) excretion (P < 0.05) after the treatment. Urinary excretion of TXB2 was significantly reduced after LDL-A (P < 0.05). The rate of entering into complete or incomplete remission was 71% with a relatively short duration of nephrotic-range proteinuria using the LDL-A therapy in comparison with steroid therapy alone.

CONCLUSION

The rapid improvement of hypercholesterolemia with LDL-A treatment may provide a new approach for a high rate of improvement in the degree of NS in steroid-resistant NS of FGS and MCNS.

Lipid-lowering therapy in patients with renal disease

A growing number of clinical trials have examined the effects of different lipid lowering strategies in patients with renal disease. We carried out a meta-analysis to compare and contrast the relative efficacy of various antilipemic therapies in different renal disease settings. Studies that investigated one or more therapies designed to lower serum lipids were combined using weighted multiple linear regression. The analysis adjusted treatment effects for differences in baseline lipid levels and possible placebo effects. The results showed that antilipemic therapies generally had similar effects on lipids in different renal disease settings. In nephrotic syndrome the greatest and most consistent reductions in low density lipoprotein cholesterol (LDL) were seen with 3-hydroxy-3-methylglutaryl co-enzyme A (HMG-CoA) reductase inhibitors (regression coefficient with 95% confidence interval in mg/dl = -63, -79 to -46). Similar results were seen for LDL in renal transplant (-51, -57 to -45), renal insufficiency (-62, -82 to -42), hemodialysis (-65, -80 to -50) and continuous ambulatory peritoneal dialysis (CAPD) patients (-84, -104 to -64). Fibric acid analogues had less effect on LDL, but caused greater reductions in triglycerides: -132, -178 to -87, in nephrotic syndrome; -69, -93 to -45 in transplant: -107, -169 to -45 in renal insufficiency; -72, -120 to -24 in hemodialysis; and -96, -162 to -30 in CAPD. In general, the effects of diet and other therapies were less consistent. Despite possible limitations of this meta-analysis, the results provide a useful framework for choosing antilipemic therapy, and point to areas for future long-term studies examining the safety and efficacy of lipid lowering strategies in patients with renal disease.

Reduction of lipoprotein(a) following treatment with lovastatin in patients with unremitting nephrotic syndrome

Pharmocologic treatment of the hyperlipidemia associated with the nephrotic syndrome with lovastatin has been previously shown to be safe and effective. However, there is no information on the effect of lovastatin treatment on plasma lipoprotein(a) [Lp(a)] levels in patients with the nephrotic syndrome. We administered lovastatin (40 to 80 mg/day) to 20 adult patients with unremitting nephrotic syndrome for 8 weeks to assess its effect on plasma Lp(a) and other plasma lipid concentrations. Apoprotein(a) (apo(a)) phenotype was determined in all patients. Patients were grouped according to their plasma Lp(a) levels. Those with elevated plasma Lp(a) (> or = 30 mg/dL) were placed in group I and those with normal Lp(a) levels (< 30 mg/dL) were placed in group II. Mean total cholesterol and LDL cholesterol were similarly and significantly reduced in groups I and II (-35.9% and -43.3%, P < 0.0005, P < 0.0005 group I, and -31.0% and -42.0%, P < 0.02, P < 0.03 group II, respectively). The median reduction in plasma Lp(a) was -32% (P < 0.003) in nephrotic patients in group I, whereas the median decline in plasma Lp(a) levels in nephrotic patients in group II was only -8.0% (P = 0.052). The overall frequency of the high molecular weight (M(r)) apo(a) phenotype S4 was 70% in nephrotic patients. There was no correlation between plasma Lp(a) and apo(a) phenotype. Treatment with lovastatin results in a favorable response in terms of total and low-density lipoprotein cholesterol lowering in patients with the nephrotic syndrome; however, plasma Lp(a) levels are uniformly and significantly reduced only in nephrotic patients with elevated baseline plasma Lp(a) concentrations. There was no correlation between plasma Lp(a) concentration and other lipid and biochemical parameters.

Fundamental concepts and immunosuppressive treatment in the various forms of glomerulonephritis

Immunosuppressive treatment in glomerulonephritis (GN) is still controversial. Most of the secondary forms of glomerulonephritis have the histologic features of one of the primary types of glomerulonephritis. Eight histologic expressions of primary glomerulonephritis can be distinguished and ordered in terms of severity of symptoms and prognosis: endocapillary GN, minimal change GN, mesangioproliferative GN, membranous GN, focal-sclerosing GN, membranoproliferative GN, focal-necrotizing GN, and rapidly progressive GN. Agreement exists only to the extent that immunosuppression is not required in endocapillary glomerulonephritis, although it is recommended in the other extreme of rapidly progressive GN. Primarily, an indication for immunosuppression is given by the severity of symptoms with a urinary protein excretion > 3.5 g per day and/or serum creatinine > 150 mumol per liter. As for anti-GBM, the type of glomerulonephritis is more important than the severity of symptoms in guiding therapy, whereas for IgA nephropathy it is controversial whether the prospective prognosis of even inexorably deteriorating renal function justifies immunosuppression. Renal biopsy is required to identify the type of glomerulonephritis so as to establish the specific immunosuppressive concept with different intensity and duration of treatment. Immunosuppression can reduce urinary protein excretion and improve deterioration of renal function; however, the proportion of patients responding varies with and depends on the different forms of GN.

The role of lipids in nephrosclerosis and glomerulosclerosis

Hyperlipidemia and lipoprotein abnormalities are often encountered in patients with nephrotic syndrome or chronic renal disease and also in those undergoing haemodialysis and with renal transplant. Even though the significance of lipid deposition in renal tissue and the role of lipoproteins in the pathogenesis of renal disease in man is unclear, experimental and clinical data indicate a possible damaging effect of a disturbed lipid metabolism on the kidney. In humans, glomerular lipid deposition is observed in genetic diseases such as Fabry's disease, lecithin:cholesterol acyltransferase activity (LCAT) deficiency and arteriohepatic dysplasia, and in diseases with acquired disturbance of lipid metabolism such as nephrotic syndrome and cholestatic liver disease. Studies on animals with lupus nephritis, aminonucleoside nephrosis, reduced renal mass, diabetes mellitus or systemic hypertension have shown that cholesterol can increase the incidence of glomerulosclerosis. As most of these studies have been performed in the rat, which has a different lipoprotein profile to that of man, these results should be carefully interpreted with regard to their relevance for humans. In vitro cell culture studies on human glomerular cells have given some preliminary insights into the cellular mechanisms of lipid induced glomerular damage. Apo E-containing lipoproteins, which are pathologically elevated in many renal diseases, are avidly taken up by human mesangial cells. These cells seem to play a central role in the initiation of glomerulosclerosis by inducing proliferation and production of excess extracellular matrix. Lipoproteins are able to stimulate DNA synthesis in these cells, and increase the synthesis of mitogens and extracellular matrix protein. The pathogenic role of oxidized lipoproteins has not yet been defined. Human mesangial cells do not seem to take up these modified lipoproteins. However, macrophages infiltrate glomeruli and may constitute the stimulus for the generation of minimally modified lipoproteins and their cellular uptake. The data from animal experiments suggest that treatment that corrects hyperlipidemia may have an ameliorative effect on renal function. Thus, there are strong indications that lipoproteins may play a critical role in mediating the development of glomerulosclerosis.

Lipid abnormalities in the nephrotic syndrome: causes, consequences, and treatment

Hyperlipidemia so commonly complicates heavy proteinuria that it has come to be regarded as an integral feature of the nephrotic syndrome (NS). Characteristically, total plasma cholesterol and triglyceride levels are elevated, as are very-low-density lipoprotein (VLDL) and low-density lipoprotein (LDL) cholesterol. Although high-density lipoprotein (HDL) concentrations may be normal, HDL subtypes are abnormally distributed, with a reduction of HDL2 and an increase in HDL3. In addition, lipoprotein (a) [Lp (a)] levels may be elevated. The mechanisms underlying these abnormalities are multifactorial, involving both increased rates of lipoprotein synthesis and defective clearance and catabolism of circulating particles. Although recent dietary and therapeutic studies have demonstrated that nephrotic hyperlipidemia can be effectively treated, the need for such intervention has not been clearly established. This pattern of lipoprotein abnormality is associated with an increased risk of cardiovascular disease in the general population, and several studies have suggested that nephrotic individuals are more likely to develop atherosclerosis. However, no prospective trials have evaluated the relationship between deranged lipid metabolism and coronary or cerebral artery disease in patients with NS. In addition, although recent experimental studies suggest that lipid abnormalities may accelerate renal injury and that lipid-lowering agents may protect renal function, there is little current evidence to suggest that such intervention is of value in preserving residual renal function in humans. Further studies are clearly required to assess the potential long-term benefits of lipid-lowering intervention in individuals with NS. In the meantime, based on data generated from other population groups, a rational approach to the clinical management of hyperlipidemia in these patients is presented.

Metabolic effects of converting enzyme inhibitors: focus on the reduction of cholesterol and lipoprotein(a) by fosinopril

It is generally believed that the use of angiotensin-converting enzyme (ACE) inhibitors has no effect on the lipid profile. Our recent data show that in patients with proteinuric renal disease, serum levels of total cholesterol and lipoprotein(a) [Lp(a)] may be lowered during treatment with an ACE inhibitor, fosinopril sodium. During a 12-week randomized, placebo-controlled, double-blind study involving 26 patients with mild-to-moderate renal impairment, fosinopril administration was associated with significant decreases in both urinary protein excretion and serum total cholesterol levels, whereas placebo was not. During a 6-week washout phase, both parameters returned to baseline in fosinopril-treated patients and remained unchanged in placebo recipients. In addition, fosinopril-treated patients had a decrease in plasma levels of Lp(a), whereas this was not seen in placebo-treated patients. When data from a subset of 13 patients with proteinuric renal disease and hypertension were examined, a significant decrease in serum total cholesterol levels was observed; this decrease reversed after discontinuation of fosinopril. Analysis of the effect of fosinopril on plasma Lp(a) levels in a subset of patients who had type II diabetes mellitus and overt proteinuria revealed a significant decrease in plasma Lp(a) after administration of fosinopril. Moreover, fosinopril lowered plasma Lp(a) levels in blacks, whose pretreatment levels were higher than those of whites with comparable degrees of proteinuria and levels of serum total cholesterol. Thus, the reduction in serum Lp(a) levels may be related not only to amelioration of proteinuria, but also to another direct action of fosinopril on the metabolism of Lp(a).

Simvastatin therapy for hypercholesterolemic patients with nephrotic syndrome or significant proteinuria

Experimental evidence suggests that lipid lowering therapy could slow the progression of renal disease in humans. We have conducted a double-blind, placebo controlled trial of the HMG CoA reductase inhibitor simvastatin in patients with the nephrotic syndrome or significant proteinuria (> 1 g/day) and hypercholesterolemia (> or = 6.5 mmol/liter). Patients were placed on a lipid lowering diet for at least 10 weeks before randomization. After a four-week placebo run-in, 30 adults were randomized to simvastatin or placebo therapy (10 mg/day, increasing to 20 to 40 mg/day as required) for 24 weeks. There were seven dropouts, none of whom were "definitely" related to drug therapy. Total and LDL cholesterol levels fell by a mean of 33 and 31%, respectively, in simvastatin treated patients, compared with only 5 and 1% in patients on placebo (P < 0.001, P = 0.002, respectively). Apolipoprotein B100 levels fell by a mean of 31% in the simvastatin group but rose 0.3% in the placebo group (P = 0.014). There were no significant changes in HDL levels. There were no significant differences between the groups in their urine protein levels, their rise in plasma creatinine, or decline in plasma inulin clearance. Simvastatin is a safe, effective therapy for hypercholesterolemia in proteinuric states. A much larger trial is needed to show if potent lipid-lowering therapy slows progression of hypercholesterolemic proteinuric diseases.

Hyperlipidemia in childhood nephrotic syndrome

Hyperlipidemia is an important characteristic of nephrotic syndrome (NS). Elevation of plasma total cholesterol, or more specifically low-density lipoprotein cholesterol, is the major lipid abnormality in NS, although hypertriglyceridemia may develop as the disorder progresses. The pathophysiology of nephrotic hyperlipidemia is complex. The prevailing view is that both hepatic synthesis of lipids and of apolipoproteins is increased, and that the clearance of chylomicrons and very low-density lipoproteins is reduced. The precise contribution of increased lipogenesis and decreased lipid catabolism to hyperlipidemia, and their relationship to urinary protein loss, hypoalbuminemia and reduced serum oncotic pressure remain controversial. There are two potential risks of elevated plasma lipids: atherosclerosis and progression of glomerular injury. Although neither of these complications has been proved with certainty, there is growing evidence that both may be long-term consequences of NS. Therefore, the diagnosis and treatment of lipid abnormalities, important aspects of the management of nephrotic children, is summarized here to provide pediatric nephrologists with an informed choice.

Influence of diet on lipid abnormalities in human renal disease

The scarce literature on dietary manipulation of dyslipidemia in patients with nephrotic syndrome and in patients with chronic renal insufficiency is reviewed. Our favorable personal experience in both clinical conditions is illustrated as well. A special low-protein soy diet given for 2 or 4 months partially corrected hypercholesterolemia in nephrotic patients, and a low-protein diet also low in cholesterol and rich in polyunsaturated fatty acids corrected hypertriglyceridemia and hypercholesterolemia in patients with progressive renal damage. The soy diet had an additional favorable effect on proteinuria of nephrotic patients that might have been a direct consequence of the partial correction of the hypercholesterolemia. The addition of 5 g/d of fish oil to the soy diet did not modify the effects of the soy diet on proteinuria nor was it able to correct the hypertriglyceridemia of nephrotic patients. Dietary intervention should be the first-line treatment for the dyslipidemia of these renal diseases, since it can be used for long periods of time and is devoid of side effects so long as good nutritional status is maintained.

Treatment of hyperlipidemia in the nephrotic syndrome: the effects of pravastatin therapy

The hyperlipidemia of the nephrotic syndrome is characterized by an elevation of total cholesterol (TC) and low-density lipoprotein cholesterol (LDLC), with a normal or low high-density lipoprotein cholesterol (HDLC), and an increase in triglycerides (TGs) later in the course of the disease. If sustained, this lipid profile probably places these patients at increased risk for cardiovascular disease. Despite extensive trials of diet and drug therapy in patients with primary hyperlipidemias, few such trials exist in patients with the nephrotic syndrome. We conducted a randomized, prospective, double-blind, placebo-controlled trial to investigate the efficacy and safety of pravastatin, the newest cholesterol synthesis inhibitor, in the treatment of the hyperlipidemia of the nephrotic syndrome. After dietary modification was implemented, 13 patients received pravastatin and eight received placebo. All patients were maintained on a low-fat, low-cholesterol diet for the duration of the trial (24 weeks). The dose of pravastatin was increased from the initial 20 mg/d to 40 mg/d at week 10 or 18 if TC remained elevated (> 50th percentile). A bile acid sequestrant was added at week 18 if TC remained elevated and if the patient was already receiving the maximal pravastatin dosage. Dietary modification did not significantly change the lipid profile. Pravastatin (20 mg/d) reduced TC by 22% from a baseline of 301 +/- 28 mg/dL (P < 0.05) and LDLC by 28% from a baseline of 222 +/- 28 mg/dL (P < 0.05). When used at 40 mg/d (in six patients) no further change in the lipid profile was observed.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of vegetarian soy diet on hyperlipidaemia in nephrotic syndrome

Nephrotic patients with persistent proteinuria also have various lipid abnormalities that may promote atherosclerosis and more rapid progression of renal disease. We aimed to find out whether dietary manipulation can correct the hyperlipidaemia found in these patients. After a baseline control period of 8 weeks on their usual diets, 20 untreated patients with chronic glomerular diseases, stable long-lasting severe proteinuria (5.9 [SD 3.4] g/24 h) and hyperlipidaemia (mean serum cholesterol 8.69 [3.34] mmol/l) ate a vegetarian soy diet for 8 weeks. The diet was low in fat (28% of total calories) and protein (0.71 [0.36] g/kg ideal body weight daily), cholesterol free, and rich in monounsaturated and polyunsaturated fatty acids (polyunsaturated/saturated ratio 2.5) and in fibre (40 g/day). After the diet period the patients resumed their usual diets for 8 weeks (washout period). During the soy-diet period there were significant falls in serum cholesterol (total, low-density lipoprotein, and high-density lipoprotein) and apolipoproteins A and B, but serum triglyceride concentrations did not change. Urinary protein excretion fell significantly. The concentrations of all lipid fractions and the amount of proteinuria tended to return towards baseline values during the washout period. We do not know whether the favourable effect of this dietary manipulation on proteinuria was due to the qualitative or quantitative modifications of dietary protein intake or was a direct consequence of the manipulation of dietary lipid intake.

Interactions of LDL and modified LDL with mesangial cells and matrix

Hyperlipidemia may play a role in the progression of diabetic and other renal diseases. Low density lipoprotein (LDL) and other proteins including extracellular matrix components undergo nonenzymatic glycation in vivo. We examined the effects of glycation of LDL as occurs in diabetes (4 to 8%) on binding and uptake by mesangial cells and their proliferation. The glycation of LDL (g-LDL) significantly decreased its binding and uptake by mesangial cells by 15 to 20%, indicating that glycated LDL binds to the LDL receptor, but with lower affinity than LDL. Both LDL and g-LDL modestly stimulated [3H] thymidine incorporation into mesangial cells at 5 to 10 micrograms/ml. Native, oxidized (Ox-LDL) and glycated LDL all bound to the extracellular matrix generated by rat mesangial cells in culture. The binding of LDL, Ox-LDL and g-LDL to mesangial matrix was two to four times higher than to mesangial cells. Binding of LDL and g-LDL was significantly higher to glycolaldehyde modified matrix, which serves as an in vitro model for nonenzymatic glycation end-product cross-linking of matrix which occurs in long-standing diabetes. Based on these findings, we propose that glycation of LDL decreases its binding and uptake by the LDL receptor of mesangial cells and may slow its catabolism. Furthermore, LDL bound to extracellular mesangial matrix can undergo oxidation and generate cytotoxic LDL components. This process may be further enhanced by advanced glycation of the mesangial matrix in diabetes, contributing to glomerular pathology.

Lipid changes in the nephrotic syndrome: new insights into pathomechanisms and treatment

The abnormalities of lipid metabolism in nephrotic syndrome consist in an increase in total and low-density lipoprotein (LDL) cholesterol, apolipoproteins B (ApoB), C-II and C-III, associated in patients with heavier or marked hypoalbuminemia with an increase in triglycerides and very low-density lipoprotein (VLDL) cholesterol, while the high-density lipoproteins (HDL) are distributed abnormally (increased HDL3 fraction and decreased HDL2 fraction) and the Apo A-I to Apo B ratio is reduced. Both increased hepatic lipoprotein synthesis and reduced removal capacity contribute to this hyperlipidemia. Proteinuria may lead to the lipoprotein abnormalities through stimulation of VLDL synthesis by the liver induced by hypoalbuminemia, although it has been more recently suggested that urinary protein loss is associated with the urinary loss of some important cofactor for the regulation of lipid synthesis or catabolism. Treatment of lipid abnormalities in patients with long-lasting heavy proteinuria is mandatory, because they may cause or contribute to accelerated atherosclerosis, but also because they appear to accelerate progression of renal disease by favouring mesangial sclerosis. Four groups of lipid-lowering drugs have been tested: 1) bile acid-binding resins; 2) fibric acid; 3) probucol; 4) inhibitors of HMG CoA reductase. The drugs of the last group appear to be effective and safe in short-term experiments, but long-term studies are necessary to confirm their validity. A dietary approach, consisting in a strictly vegetarian soy diet, very rich in poly- and monounsaturates fatty acids, has been recently tested by the author, with very promising results.

[Pathophysiology and therapy of lipid metabolism disorders in kidney diseases]

Nephrotic syndrome, uremia, hemodialysis, peritoneal dialysis, and renal transplantation are accompanied by alterations in lipoprotein metabolism In nephrotic patients, total cholesterol, LDL, VLDL and triglycerides are elevated, while HDL may be increased, normal, or decreased. The pathophysiology includes increased hepatic synthesis of VLDL and cholesterol, decreased activity of lipoprotein lipase, and increased urinary excretion of HDL. The risk of coronary heart disease (CHD) is increased in nephrotic patients and elevated LDL-cholesterol may contribute to this risk. Cholesterol lowering diet and drugs are indicated. Presently, Lovastatin and Simvastatin are the most potent cholesterol lowering drugs in nephrotic patients with good evidence of long-term safety. Most patients with impaired renal function or on hemodialysis have moderate hypertriglyceridemia due to decreased lipoprotein lipase activity. HDL may be slightly decreased. Although the risk of CHD is increased in these patients, triglyceride lowering drugs are not indicated, since no benefit can be expected. Peritoneal dialysis is accompanied by elevated VLDL in addition to hypertriglyceridemia. Reabsorption of large amounts of glucose from peritoneal dialysis fluid increases the carbohydrate load and stimulates hepatic VLDL synthesis. Cholesterol lowering therapy may be advantageous, but the experience is very limited. Side effects of lipid lowering drugs may be aggravated in renal failure. Total cholesterol, LDL, VLDL, and triglycerides are elevated in 50% of patients following renal transplantation. Corticosteroids and cyclosporin are major causes of hyperlipidemia. Cholesterol lowering therapy is indicated since the incidence of CHD is increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of HMG-CoA reductase inhibitors in hypercholesterolemic patients on hemodialysis

The efficacy of lovastatin and simvastatin, competitive inhibitors of 3-hydroxy-3-methyl glutaryl coenzyme A reductase, was investigated in 40 hemodialysis (HD) patients displaying hypercholesterolemia and moderate hypertriglyceridemia (selection of 40 patients required screening of 700 hemodialysis patients). After a four-week placebo period, lovastatin or simvastatin was administered to two groups of 20 patients in increasing doses over a period of three months. Thirty-six patients completed the study. Lovastatin (1st month 20 mg; 2nd and 3rd months 40 mg day-1) and simvastatin (1st month 10 mg, 2nd month 20 mg and 3rd month 40 mg day-1) reduced total serum cholesterol from 280.3 +/- 9.4 to 213.0 +/- 6.7 (-24%) and 295.0 +/- 12.2 to 202.3 +/- 8.9 mg/dl (-31.4%), LDL cholesterol from 161.9 +/- 10.7 to 112.1 +/- 7.9 (-30.8%) and 181.8 +/- 14.7 to 107.4 +/- 8.1 mg/dl (-40.9%), as well as apolipoprotein B (apo B) from 116.0 +/- 6.6 to 83.3 +/- 3.7 (-28.2%) and 134.4 +/- 8.2 to 84.1 +/- 5.3 mg/dl (-37.4%), respectively. Furthermore, the ratio of LDL apo B/LDL cholesterol increased significantly (0.63 +/- 0.02 vs. 0.71 +/- 0.05 and 0.63 +/- 0.02 vs. 0.66 +/- 0.02, respectively). Another remarkable effect was the reduction of cholesterol concentration in VLDL (72.4 +/- 8.9 vs. 47.3 +/- 6.8 [lovastatin] and 78.3 +/- 11.1 vs. 50.7 +/- 8.8 mg/dl [simvastatin], respectively). Therefore, the ratio of triglycerides/cholesterol in VLDL increased (3.2 +/- 0.2 vs. 3.8 +/- 0.3 and 3.2 +/- 0.2 vs. 4.0 +/- 0.2, respectively), indicating VLDL formation poor in cholesterol and rich in triglycerides.(ABSTRACT TRUNCATED AT 250 WORDS)