Lipids and the kidney

Association of Renal Function and Statin Therapy with Lipoprotein(a) in Patients with Type 2 Diabetes

AIM

A high level of serum lipoprotein(a) [Lp(a)] is associated with kidney disease development in patients with type 2 diabetes (T2DM). Recent studies have suggested that statins may affect serum levels of Lp(a). However, the statin effect is not well-defined in patients with T2DM with kidney dysfunction. This retrospective study aimed to investigate the relevance of kidney dysfunction and statin therapy to Lp(a) in patients with T2DM.

METHODS

Japanese patients with T2DM (n=149, 96 men and 53 women) were divided into two groups: statin users (n=79) and non-statin users (n=70). Multiple logistic regression analyses were performed with Lp(a) as the objective variable and estimated glomerular filtration rate (eGFR), hemoglobin A1c, age, gender, and body mass index as the explanatory variables.

RESULTS

Lp(a) serum levels were higher in statin users than in non-statin users (P=0.022). Multivariate regression analysis results showed an inverse correlation of eGFR to log Lp(a) in all patients (P=0.009) and in non-statin users (P=0.025), but not in statin users. In a multiple logistic regression analysis for median Lp(a), there was an inverse association between eGFR and Lp(a) level (odds ratio, 0.965; 95% confidence interval, 0.935-0.997; P=0.030) in non-statin users as well as in all participants, but not in statin users.

CONCLUSIONS

The present study suggests that a high Lp(a) level in patients with T2DM, except in statin users, is significantly associated with decreased eGFR, indicating that the increased Lp(a) levels under statin therapy might diminish the relationship between Lp(a) and eGFR.

Autosomal Recessive Hypercholesterolemia Caused by a Novel LDLRAP1 Variant and Membranous Nephropathy in a Chinese Girl: A Case Report

Background

Autosomal recessive familial hypercholesterolemia (ARH) is a very rare lipid metabolic monogenic disorder caused by homozygosity or compound heterozygosity for mutations in the low-density lipoprotein receptor adapter protein 1 (LDLRAP1) gene. It is a life-threatening disease characterized by markedly elevated low-density lipoprotein cholesterol (LDL-C), xanthomas, and premature coronary artery disease. Membranous nephropathy (MN) is less commonly observed in children. Here, the co-existence of ARH and MN was diagnosed in a Chinese girl.

Case Presentation

We present the case of a 13-year-old girl who was admitted with the typical symptom of nephrotic syndrome with an abnormally high serum LDL-C level. Gene sequencing revealed a novel homozygous LDLRAP1 variant (NM_015627: c.383 T>G, p.V128G), and the patient was diagnosed with ARH. A renal biopsy suggested that the nephrotic syndrome in the girl was induced by MN, but no evidence of secondary MN was found. A thorough examination was performed to explore the association between MN and ARH. Medical management with angiotensin receptor blockers and aggressive lipid-lowering treatment led to remission of proteinuria and clinical condition stabilization during 2-year follow-up.

Conclusions

This is the first case of co-existence of MN and ARH in a teenager carrying a novel pathogenic mutation of the LDLRAP1 gene (NM_015627: c.383 T>G, p.V128G).

Serum lipoprotein (a) associates with the risk of renal function damage in the CHCN-BTH Study: Cross-sectional and Mendelian randomization analyses

BACKGROUND

Evidence regarding the effects of lipoprotein (a) [lp(a)] and renal function remains unclear. The present study aimed to explore the causal association of serum lp(a) with renal function damage in Chinese general adults.

METHODS

A total of 25343 individuals with available lp(a) data were selected from the baseline survey of the Cohort Study on Chronic Disease of Communities Natural Population in Beijing, Tianjin, and Hebei (CHCN-BTH). Five renal function indexes [estimated glomerular filtration rate (eGFR), serum creatinine (Scr), blood urea nitrogen (BUN), uric acid (UA), high-sensitivity C-reactive protein(CRPHS)] were analyzed. The restricted cubic spline (RCS) method, logistic regression, and linear regression were used to test the dose-response association between lp(a) and renal function. Stratified analyses related to demographic characteristics and disease status were performed. Two-sample Mendelian randomization (MR) analysis was used to obtain the causal association of lp(a) and renal function indexes. Genotyping was accomplished by MassARRAY System.

RESULTS

Lp(a) levels were independently associated with four renal function indexes (eGFR, Scr, BUN, CRPHS). Individuals with a higher lp(a) level had a lower eGFR level, and the association with Scr estimated GFR was stronger in individuals with a lower lp(a) level (under 14 mg/dL). . The association was similar in individuals regardless of diabetes or hypertension. MR analysis confirmed the causal association of two renal function indexes (Scr and BUN). For MR analysis, each one unit higher lp(a) was associated with 7.4% higher Scr (P=0.031) in the inverse-variance weighted method. But a causal effect of genetically increased lp(a) level with increased eGFR level which contrasted with our observational results was observed.

CONCLUSION

The observational and causal effect of lp(a) on Scr and BUN were founded, suggesting the role of lp(a) on the risk of renal function damage in general Chinese adults.

Dyslipidemia and cardiovascular health in childhood nephrotic syndrome

Children with steroid-resistant nephrotic syndrome (SRNS) are exposed to multiple cardiovascular risk factors predisposing them to accelerated atherosclerosis. This risk is negligible in steroid-sensitive nephrotic syndrome, but a substantial proportion of children with SRNS progress to chronic kidney disease, exacerbating the already existing cardiovascular risk. While dyslipidemia is an established modifiable risk factor for cardiovascular disease in adults with NS, it is uncertain to what extent analogous risks exist for children. There is increasing evidence of accelerated atherosclerosis in children with persistently high lipid levels, especially in refractory NS. Abnormalities of lipid metabolism in NS include hypertriglyceridemia and hypercholesterolemia due to elevated apolipoprotein B-containing lipoproteins, decreased lipoprotein lipase and hepatic lipase activity, increased hepatic PCSK9 levels, and reduced hepatic uptake of high-density lipoprotein. Existing guidelines for the management of dyslipidemia in children may be adapted to target lower lipid levels in children with NS, but they will most likely require both lifestyle modifications and pharmacological therapy. While there is a lack of data from randomized controlled trials in children with NS demonstrating the benefit of lipid-lowering drugs, therapies including statins, bile acid sequestrants, fibrates, ezetimibe, and LDL apheresis have all been suggested and/or utilized. However, concerns with the use of lipid-lowering drugs in children include unclear side effect profiles and unknown long-term impacts on neurological development and puberty. The recent introduction of anti-PCSK9 monoclonal antibodies and other therapies targeted to the molecular mechanisms of lipid transport disrupted in NS holds promise for the future treatment of dyslipidemia in NS.

Serum lipoprotein (a) associates with a higher risk of reduced renal function: a prospective investigation

Lipoprotein (a) [Lp(a)] is a well-known risk factor for cardiovascular disease, but analysis on Lp(a) and renal dysfunction is scarce. We aimed to investigate prospectively the association of serum Lp(a) with the risk of reduced renal function, and further investigated whether diabetic or hypertensive status modified such association. Six thousand two hundred and fifty-seven Chinese adults aged ≤40 years and free of reduced renal function at baseline were included in the study. Reduced renal function was defined as estimated glomerular filtration rate <60 ml/min/1.73 m². During a mean follow-up of 4.4 years, 158 participants developed reduced renal function. Each one-unit increase in log₁₀-Lp(a) (milligrams per deciliter) was associated with a 1.99-fold (95% CI 1.15–3.43) increased risk of incident reduced renal function; the multivariable-adjusted odds ratio (OR) for the highest tertile of Lp(a) was 1.61 (95% CI 1.03–2.52) compared with the lowest tertile (P for trend = 0.03). The stratified analysis showed the association of serum Lp(a) and incident reduced renal function was more prominent in participants with prevalent diabetes [OR 4.04, 95% CI (1.42–11.54)] or hypertension [OR 2.18, 95% CI (1.22–3.89)]. A stronger association was observed in the group with diabetes and high Lp(a) (>25 mg/dl), indicating a combined effect of diabetes and high Lp(a) on the reduced renal function risk. An elevated Lp(a) level was independently associated with risk of incident reduced renal function, especially in diabetic or hypertensive patients.

[Lipid spectrum and function of kidneys before and after liver transplantation]

BACKGROUND

In patients after liver transplantation cardiovascular complications is the third main reason of death afer allograf failure and infections. The most important factors in the development of cardiovascular diseases are dyslipidemia and impaired renal function. The aim of the study was to investigate the lipid spectrum and renal function in liver recipients in real clinical practice and the correspondence of their correction to current clinical recommendations for the diagnosis and treatment of dyslipidemia and chronic kidney disease (CKD).

METHODS

A retrospective analysis of lipid spectrum and renal function in patients who underwent OLT in Research Institute - Regional Clinical Hospital №1, Krasnodar was performed. The level of creatinine, GFR and lipid spectrum was studied before and 36 months after liver transplantation. The GFR was calculated using the formula CKD‑EPI (Chronic Kidney Disease Epidemiology Collaboration). Statistical analysis of the study results was made using the program Statistica 10.

RESULTS

Liver recipients have a significantly higher total cholesterol by 31.0% (p&lt;0.01) in comparison with the baseline before surgery. Total cholesterol was increased in 13.7% (p&lt;0.01), triglycerides in 12.3% (p&lt;0.01) before transplantation. Tree years after transplantation, the increasion in cholesterol was registered in 42.6% (p&lt;0.01) and triglycerides in 37.9% (p &lt;0.01), respectively. 3 years after transplantation reduction of GFR was observed in comparison with the baseline by 22.6% (p=0.00006). Verification of chronic kidney disease and statin administration in patients were carried out in some cases. The levels of total cholesterol and triglycerides had a reliable inverse correlation with GFR (r = ‑0.42; p&lt;0.01 and r = ‑0.36; p&lt;0.05).

CONCLUSIONS

In the long‑term postoperative period there was an impaired lipid metabolism and decreased level of GFR. Dyslipidemia was closely related to the progression of renal dysfunction in liver recipients, an inverse correlation was established between the glomerular filtration rate and the increasion in cholesterol and triglyceride levels. It is necessary to increase the attention of physicians with regard to timely correction of lipid metabolism disorders and detection of initial manifestations of renal dysfunction.

Effect of atorvastatin on dyslipidemia and carotid intima-media thickness in children with refractory nephrotic syndrome: a randomized controlled trial

BACKGROUND

Dyslipidemia is an important cardiovascular risk factor in steroid-resistant nephrotic syndrome (SRNS). Efficacy of statins for treatment of hyperlipidemia in children with SRNS is unclear.

METHODS

This prospective, randomized, double-blind, placebo-controlled, parallel-group clinical trial enrolled 30 patients with SRNS, aged 5-18 years, with serum low-density lipoprotein cholesterol (LDL-C) levels between 130 and 300 mg/dl, to receive a fixed dose of atorvastatin (n = 15, 10 mg/d) or placebo (n = 15) by block randomization in a 1:1 ratio. Primary outcome was change in serum LDL-C at 12 months. Change in levels of other lipid fractions, carotid intima-media thickness (cIMT), flow-mediated dilation (FMD) of the brachial artery, and adverse events were also evaluated.

RESULTS

At the end of 12 months, atorvastatin was not superior to placebo in reducing plasma LDL-C levels, median percentage reduction 15.8% and 9.5% respectively, in atorvastatin and placebo arms (n = 14 in each; P = 0.40). Apolipoprotein B levels significantly declined with atorvastatin in modified intention-to-treat analysis (P = 0.01) but not in the per-protocol analysis. There was no significant effect on other lipid fractions, cIMT and FMD. Adverse events were similar between groups. Change in serum albumin was negatively associated with change in serum LDL-C, very low-density lipoprotein cholesterol, total cholesterol, triglyceride, and apolipoprotein B (P < 0.001), irrespective of receiving atorvastatin, age, gender, body mass index, and serum creatinine.

CONCLUSIONS

Atorvastatin, administered at a fixed daily dose of 10 mg, was not beneficial in lowering lipid levels in children with SRNS; rise in serum albumin was associated with improvement in dyslipidemia.

The effect of cholesterol overload on mouse kidney and kidney-derived cells

Introduction: Dyslipidemia is one of the onset and risk factors of chronic kidney disease and renal function drop is seen in lipoprotein abnormal animal models. However, the detailed molecular mechanism of renal lipotoxicity has not been clarified. Therefore, the present study aimed to investigate the influence of cholesterol overload using mouse kidney tissue and kidney-derived cultured cells.

Methods: C57BL/6 mice were fed normal diet (ND) or 1.25% cholesterol-containing high-cholesterol diet (HCD) for 11 weeks, and we used megalin as a proximal tubule marker for immunohistology. We added beta-very low density lipoprotein (βVLDL) to kidney-derived cells and examined the effect of cholesterol overload on megalin protein and mRNA expression level, cell proliferation and cholesterol content in cells.

Results: In the kidney of HCD mice, the gap between glomerulus and the surrounding Bowman’s capsule decreased and the expression level of megalin decreased. After βVLDL treatment to the cells, the protein expression and mRNA expression level of megalin decreased and cell proliferation was restrained. We also observed an increase in cholesterol accumulation in the cell and free cholesterol/phospholipid ratios increased.

Conclusions: These findings suggest that the increased cholesterol load on kidney contribute to the decrease of megalin and the overloaded cholesterol is taken into the renal tubule epithelial cells, causing suppression on cell proliferation, which may be the cause of kidney damage.

Dyslipidaemia in nephrotic syndrome: mechanisms and treatment

Nephrotic syndrome is a highly prevalent disease that is associated with high morbidity despite notable advances in its treatment. Many of the complications of nephrotic syndrome, including the increased risk of atherosclerosis and thromboembolism, can be linked to dysregulated lipid metabolism and dyslipidaemia. These abnormalities include elevated plasma levels of cholesterol, triglycerides and the apolipoprotein B-containing lipoproteins VLDL and IDL; decreased lipoprotein lipase activity in the endothelium, muscle and adipose tissues; decreased hepatic lipase activity; and increased levels of the enzyme PCSK9. In addition, there is an increase in the plasma levels of immature HDL particles and reduced cholesterol efflux. Studies from the past few years have markedly improved our understanding of the molecular pathogenesis of nephrotic syndrome-associated dyslipidaemia, and also heightened our awareness of the associated exacerbated risks of cardiovascular complications, progressive kidney disease and thromboembolism. Despite the absence of clear guidelines regarding treatment, various strategies are being increasingly utilized, including statins, bile acid sequestrants, fibrates, nicotinic acid and ezetimibe, as well as lipid apheresis, which seem to also induce partial or complete clinical remission of nephrotic syndrome in a substantial percentage of patients. Future potential treatments will likely also include inhibition of PCSK9 using recently-developed anti-PCSK9 monoclonal antibodies and small inhibitory RNAs, as well as targeting newly identified molecular regulators of lipid metabolism that are dysregulated in nephrotic syndrome.

Statins and Renin Angiotensin System Inhibitors Dose-Dependently Protect Hypertensive Patients against Dialysis Risk

Background

Taiwan has the highest renal disease incidence and prevalence in the world. We evaluated the association of statin and renin–angiotensin system inhibitor (RASI) use with dialysis risk in hypertensive patients.

Methods

Of 248,797 patients who received a hypertension diagnosis in Taiwan during 2001–2012, our cohort contained 110,829 hypertensive patients: 44,764 who used RASIs alone; 7,606 who used statins alone; 27,836 who used both RASIs and statins; and 33,716 who used neither RASIs or statins. We adjusted for the following factors to reduce selection bias by using propensity scores (PSs): age; sex; comorbidities; urbanization level; monthly income; and use of nonstatin lipid-lowering drugs, metformin, aspirin, antihypertensives, diuretics, and beta and calcium channel blockers. The statin and RASI use index dates were considered the hypertension confirmation dates. To examine the dose–response relationship, we categorized only statin or RASI use into four groups in each cohort: <28 (nonusers), 28–90, 91–365, and >365 cumulative defined daily doses (cDDDs).

Results

In the main model, PS-adjusted hazard ratios (aHRs; 95% confidence intervals [CIs]) for dialysis risk were 0.57 (0.50–0.65), 0.72 (0.53–0.98), and 0.47 (0.41–0.54) in the only RASI, only statin, and RASI + statin users, respectively. RASIs dose-dependently reduced dialysis risk in most subgroups and in the main model. RASI use significantly reduced dialysis risk in most subgroups, regardless of comorbidities or other drug use (P < 0.001). Statins at >365 cDDDs protected hypertensive patients against dialysis risk in the main model (aHR = 0.62, 95% CI: 0.54–0.71), regardless of whether a high cDDD of RASIs, metformin, or aspirin was used.

Conclusion

Statins and RASIs independently have a significant dose-dependent protective effect against dialysis risk in hypertensive patients. The combination of statins and RASIs can additively protect hypertensive patients against dialysis risk.

Lipoprotein(a) predicts a new onset of chronic kidney disease in people with Type 2 diabetes mellitus

AIMS

We investigated the association between lipoprotein(a) [Lp(a)] level and new-onset chronic kidney disease (CKD) in patients with Type 2 diabetes.

METHODS

We conducted a prospective cohort study from March 2003 to December 2004 with a median follow-up time of 10.1 years. Patients aged 25-75 years with Type 2 diabetes and without CKD [estimated glomerular filtration rate (eGFR) ≥ 90 ml/min/1.73 m(2) ) were consecutively enrolled. The eGFR was measured at least twice every year , and new-onset CKD was defined as a decreased eGFR status of < 60 ml/min/1.73 m(2) using a Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation.

RESULTS

Of the 862 patients who were enrolled, 560 (65.0%) completed the follow-up and 125 (22.3%) progressed to CKD. The mean age and duration of diabetes were 53.3 ± 9.6 and 7.5 ± 6.0 years, respectively. The baseline eGFR was 101.8 ± 11.3 ml/min/1.73 m(2) . After adjusting for multiple confounding factors, a Cox hazard regression analysis revealed that the third tertile of Lp(a) was significantly associated with the development of CKD during the observation period when compared with the first tertile [hazard ratio 2.12 (95% confidence interval 1.33-3.36); P = 0.001).

CONCLUSIONS

In this prospective, longitudinal, observational cohort study, we demonstrated that the Lp(a) level was an independent prognostic factor for the future development of CKD in patients with Type 2 diabetes.

Renal Lipotoxicity-Associated Inflammation and Insulin Resistance Affects Actin Cytoskeleton Organization in Podocytes

In the last few decades a change in lifestyle has led to an alarming increase in the prevalence of obesity and obesity-associated complications. Obese patients are at increased risk of developing hypertension, heart disease, insulin resistance (IR), dyslipidemia, type 2 diabetes and renal disease. The excess calories are stored as triglycerides in adipose tissue, but also may accumulate ectopically in other organs, including the kidney, which contributes to the damage through a toxic process named lipotoxicity. Recently, the evidence suggests that renal lipid accumulation leads to glomerular damage and, more specifically, produces dysfunction in podocytes, key cells that compose and maintain the glomerular filtration barrier. Our aim was to analyze the early mechanisms underlying the development of renal disease associated with the process of lipotoxicity in podocytes. Our results show that treatment of podocytes with palmitic acid produced intracellular accumulation of lipid droplets and abnormal glucose and lipid metabolism. This was accompanied by the development of inflammation, oxidative stress and endoplasmic reticulum stress and insulin resistance. We found specific rearrangements of the actin cytoskeleton and slit diaphragm proteins (Nephrin, P-Cadherin, Vimentin) associated with this insulin resistance in palmitic-treated podocytes. We conclude that lipotoxicity accelerates glomerular disease through lipid accumulation and inflammation. Moreover, saturated fatty acids specifically promote insulin resistance by disturbing the cytoarchitecture of podocytes. These data suggest that renal lipid metabolism and cytoskeleton rearrangements may serve as a target for specific therapies aimed at slowing the progression of podocyte failure during metabolic syndrome.

[Is paraoxonase 1 a marker of cardiovascular risk in youth with type 1 diabetes? (Study about 109 cases)]

OBJECTIVES

We purpose to verify if paraoxonase 1 (PON1) activity may be a marker of cardiovascular risk in a young Tunisian population with type 1 diabetes (T1D).

METHODS

PON1 activity was measured by a kinetic method using paraoxon as substrate. The other parameters were determined by automated methods.

RESULTS

One hundred and nine children and adolescents with T1D and 97 healthy subjects were involved in this study. PON1 activity and PON1/HDL-cholesterol ratio were significantly decreased in diabetics (303 ± 174 vs. 372 ± 180 U/L and 221 ± 139 vs. 298 ± 20 1U/mmol, P=0.006, P=0.002, respectively) compared to controls. A significant increase in total cholesterol, LDL-c and microalbuminuria was observed in diabetics compared to controls. PON1 activity was decreased by 9.5% in patients with diabetes duration ≥ 6 years, by 28.4% for those with fasting glycemia ≥ 7 mmol/L (P<0.001), by 14% in those with HbA1c ≥ 8% and by 12.3% for diabetics with dyslipidemia. PON1 activity is reduced when the number of cardiovascular risk factors increases (P<0.001).

CONCLUSION

PON1 seems to be associated to cardiovascular risk markers in T1D. This result remains to be seen. Nevertheless, improving PON1 activity could be a significant target for reducing cardiovascular risk.

Lipid-lowering agents for nephrotic syndrome

BACKGROUND

Nephrotic syndrome is the collective name given to a group of symptoms that include proteinuria, lipiduria, hypoalbuminaemia, oedema, hypercholesterolaemia, elevated triglycerides, and hyperlipidaemia. Hyperlipidaemia is thought to aggravate glomerulosclerosis (hardening of blood vessels in the kidneys) and enhance progression of glomerular disease. Studies have established that reduction in total cholesterol and low density lipoprotein (LDL) cholesterol is associated with reduction in risk of cardiovascular diseases. In 2011, the European Society of Cardiology and European Atherosclerosis Society guidelines for the management of dyslipidaemia recommended use of statins as first-line agents in the management of nephrotic dyslipidaemia. However, the effectiveness and safety of statins for people with nephrotic syndrome remains uncertain. Furthermore, the efficacy of second-line lipid-lowering drugs, such as ezetimibe and nicotinic acid, has not been proven in patients with nephrotic syndrome who are unable to tolerate statin therapy.

OBJECTIVES

This review aimed to evaluate the benefits and harms of lipid-lowering agents in adults and children with nephrotic syndrome.

SEARCH METHODS

We searched the Cochrane Renal Group's Specialised Register (to 18 March 2013) through contact with the Trials Search Co-ordinator using search terms relevant to this review.

SELECTION CRITERIA

All randomised controlled trials (RCTs) and quasi-RCTs (RCTs in which allocation to treatment was obtained by alternation, use of alternate medical records, date of birth or other predictable methods) looking at participants with nephrotic syndrome that compared any lipid-lowering agent to placebo, no treatment or other lipid-lowering agents, given for not less than four weeks, were included.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study eligibility and risk of bias, and extracted data. Statistical analyses were performed using a random effects model. Dichotomous results were expressed as risk ratios (RR) with 95% confidence intervals (CI). For continuous measures mean difference (MD) was used, or the standardised mean difference (SMD) where different scales had been used.

MAIN RESULTS

We included five RCTs enrolling a total of 203 participants. Of these, four studies compared statins with no treatment or placebo, and one compared fibrates with placebo. We found no published studies comparing second-line agents such as ezetimibe, bile acid sequestrants, and nicotinic acid with placebo or no treatment. Our assessment of the risk of bias found that one study was judged overall to be at low risk of bias and the remaining four were judged to be at high risk of bias.Most outcomes were supported by single study data. One study reported significantly increased high density lipoprotein (HDL) cholesterol among participants in the statin arm compared with the no treatment group (MD 5.40 mg/dL, 95% CI 2.31 to 8.49). Another study reported higher serum albumin in the statin group compared to those who received no treatment (MD 0.60 g/dL, 95% CI 0.14 to 1.06). No serious adverse events, such as rhabdomyolysis, were reported, however some minor events occurred. One study reported no significant difference in the number of participants with elevated liver enzymes (RR 3.00, 95% CI 0.13 to 69.52); three studies reported liver enzymes remained within the normal range (no data provided). Four studies reported creatinine phosphokinase (CPK). One study indicated that CPK values fluctuated in both the simvastatin and placebo groups (no data provided); the remaining three studies reported CPK either stayed within the normal range (one study) or there was no significant difference between the lipid lowering agents and placebo.

AUTHORS' CONCLUSIONS

None of the included studies reported patient-centred outcomes including all-cause mortality, cardiovascular mortality, or non-fatal myocardial infarction; only single studies reported cholesterol (HDL, LDL and total cholesterol), triglycerides, serum creatinine, blood urea nitrogen, liver enzymes, and protein (serum, urine). High quality RCTs need to be conducted to assess the safety and efficacy of lipid-lowering drugs for people with nephrotic syndrome.

Vitamin E and regression of hypercholesterolemia-induced oxidative stress in kidney

Hypercholesterolemia (HC) is an independent risk factor for the onset and progression of renal disease. HC induces oxidative stress (OS) in the kidney; Vitamin E (Vit.E), an antioxidant, slows the progression of OS in the kidney. This study was to investigate if Vit.E regresses the HC-induced OS, and the regression is associated with an increase in the antioxidant reserve (AR). The studies were carried out in four groups of rabbits. The kidneys were removed under anesthesia. OS and AR in the renal tissue were assessed by measuring malondialdetyde (MDA) and chemiluminescent (CL) activity, respectively. High-cholesterol diet elevated the serum total cholesterol (TC), and the regular diet with or without Vit.E following a high-cholesterol diet reduced the serum TC to control levels. HC increased the MDA levels of kidney by 5.54-fold compared to control. The MDA contents of the kidneys in groups on regular diet with or without Vit.E were, respectively, 56 and 53 % lower than the control group. The CL activity in the control group was 12.15 ± 0.73 × 10(6) RLU/mg protein. The CL activity in HC group was 45.26 % lower than that in control, indicating an increase in AR. The regular diet with or without Vit.E following high-cholesterol diet normalized the CL activity/AR. In conclusion, HC increases OS in the kidney; reduction of serum cholesterol by regular diet regresses the renal OS but Vit.E does not regress HC-induced OS in kidney.

Therapeutic approaches to slowing the progression of diabetic nephropathy - is less best?

OBJECTIVE

Angiotensin II receptor blockers (ARBs) and angiotensin-converting enzyme (ACE) inhibitors are known to reduce proteinuria and have been the first-line agents in the management of diabetic nephropathy for the past 20 years. This review covers recent studies that compare the benefit of additional blockage of the renin-angiotensin-aldosterone system through combination therapy with an ACE inhibitor and ARB, or a direct renin inhibitor (DRI), to monotherapy.

DESIGN

Primary and review articles that addressed the pathophysiology, diagnosis, and therapeutic options for attenuating the progression of diabetic nephropathy were retrieved through a MEDLINE search (January 1990 to December 2012) and the bibliographies of identified articles were reviewed. English language sources were searched using the following search terms: diabetes mellitus, nephropathy, proteinuria, ACE inhibitors, ARBs, and DRIs.

SETTING

Randomized, placebo-controlled, short- and long-term studies published in peer-reviewed journals that were determined to be methodologically sound, with appropriate statistical analysis of the results, were selected for inclusion in this review.

PARTICIPANTS

Adult (≥18 years) patients with diabetic nephropathy.

MEASUREMENTS

Serum creatinine level was used to estimate glomerular filtration rate (GFR). GFR was calculated using the four-variable Modification of Diet in Renal Disease formula. The urine albumin-to-creatinine ratio was measured at baseline and at the conclusion of each study. A value between 3.4 mg/mmol and below 33.9 mg/mmol was defined as microalbuminuria. A value of 33.9 mg/mmol or more (approximately 300 mg/g creatinine) was defined as macroalbuminuria.

RESULTS

ACE inhibitors and ARBs are now the mainstay of treatment for diabetic nephropathy. However, combination therapy with an ACE inhibitor and an ARB, or DRI, has not been found to be more effective than monotherapy with an ACE inhibitor or ARB, and may increase the risk of hyperkalemia or acute kidney injury.

CONCLUSION

Both ACE inhibitors and ARBs remain the first-line agents in attenuating the progression of diabetic nephropathy; however, recent studies suggest that combining an ACE inhibitor with an ARB, or combining a DRI with an ACE inhibitor or ARB, may increase adverse events without clinical benefits to offset them.

Effects of statins on cardiorenal syndrome

Cardiovascular disease and renal disease have a close relationship that forms a vicious cycle as a cardiorenal syndrome (CRS). Oxidative stress, endothelial dysfunction, and vascular inflammation could be therapeutic targets when the renin-angiotensin-aldosterone system is activated by accumulation of conventional cardiovascular risk factors; however, a strategy for management of CRS has not been established yet. Statins, HMG-CoA reductase inhibitors, have not only cholesterol-lowering effects but also pleiotropic effects on cardiovascular systems, including anti-inflammatory and antioxidant effects and improvement of nitric oxide bioavailability. Since recent studies have indicated that statins have beneficial effects on chronic kidney disease and heart failure as well as coronary artery disease in cholesterol-lowering-dependent/independent manners, treatment with statins might be a successful strategy for preventing deterioration of CRS.

Interleukin-10 expression induced by adeno-associated virus vector suppresses proteinuria in Zucker obese rats

Varying degrees of metabolic abnormalities mediated by chronic inflammation are implicated in the chronic glomerular injuries associated with obesity. Interleukin (IL)-10, a pleiotropic cytokine, exerts anti-inflammatory effects in numerous biological settings. In the present study, we explored the biological benefits of adeno-associated virus (AAV) vector-mediated sustained IL-10 expression against the pathological renal characteristics observed in Zucker fatty rats (ZFRs). We injected an AAV vector, encoding rat IL-10 or enhanced green fluorescent protein (GFP) into male ZFRs at 5 weeks of age. Subsequently, the renal pathophysiological changes were analyzed. Persistent IL-10 expression significantly reduced the urinary protein excretion of ZFRs compared with GFP expression (47.1±11.6 mg per mg·creatinine versus 88.8±30.0 mg per mg·creatinine, P<0.01). The serum levels of IL-10 negatively correlated with the urinary protein in AAV-treated rats (r=-0.78, P<0.01). Renal hypertrophy, increased widths in the glomerular basement membrane, and the lack of uniformity and regularity of the foot process of the visceral glomerular epithelial cells of ZFRs were significantly blunted by IL-10 expression. IL-10 also abrogated the downregulation of glomerular nephrin observed in ZFRs treated with the GFP vector. Our findings provide insights into the potential benefit of the anti-inflammatory effects of IL-10 on the overall management of glomerulopathy induced by the metabolic disorders associated with obesity.

Lipoprotein Metabolism Abnormalities in Patients with Chronic Renal Insufficiency

Patients with chronic renal insufficiency (CRI) on hemodialysis develop lipoprotein abnormalities that may contribute to increased risk for atherosclerosis. The objective of this study was to assess the atherogenic risk of chronic renal insufficiency patients and dialysis treated patients (DTP) by measuring total cholesterol (TC), triglycerides (TG), HDL-cholesterol (HDL-C), LDL-cholesterol (LDL-C) and calculating the risk factor ratio: TC/HDL-C and LDL-C/HDL-C. The examined group consisted of 18 chronic renal insufficiency patients and 60 patients on hemodialysis. The results were compared to a control group of 85 voluntary blood donors. Serum lipid parameters were examined by standard methods. All lipid parameters in hemodialysis patients were statistically different as compared to the control group (p<0.05) while chronic renal insufficiency patients showed significant difference only in triglycerides and HDL-cholesterol. Hypertriglyceridemia was present in both examined groups of patients and HDL-cholesterol was lower within both groups. All calculated atherogenic ratios were higher for patients than the control group. Lipid parameters were compared between chronic renal insufficiency and hemodialysis patients, but statistically significant difference was obtained only for HDL-cholesterol (p<0.05). The increased values of triglycerides and lower HDL-cholesterol in chronic renal insufficiency patients contribute to high incidence of cardiovascular disease. Chronic renal insufficiency patients have impaired reverse cholesterol transport from peripheral cells to lipoproteins, decreased levels of HDL-cholesterol, hypertriglyceridemia prevalence of small, dense LDL and increased levels of potentially atherogenic remnant particles.

Effect of interleukin-6 receptor blockage on renal injury in apolipoprotein E-deficient mice

Hyperlipidemia has been demonstrated to be associated with renal disease, yet the mechanism of renal injury is still poorly understood. Inflammation that occurs with the hyperlipidemia has been considered to play an important role in development of glomerular injury. In the present study, we investigated the role of interleukin-6 (IL-6), a key inflammatory molecule, on renal injury in apolipoprotein E-deficient (ApoE(-/-)) mice with severe hypercholesterolemia. The 6-wk-old mice were fed a high-fat diet and administered weekly rat anti-IL-6 receptor monoclonal antibody (MR16-1), control rat IgG, or saline for a total of 4 wk. We examined histopathological changes in the kidney and urinary excretion of protein and albumin. Saline- and IgG-treated mice showed remarkable proteinuria at 10 wk of age, whereas MR16-1-treated mice exhibited significantly lower levels. Renal histopathology of saline- and IgG-treated mice revealed striking lipid deposits and foam cells in the glomerular tuft, juxtaglomerular area, and arteriolar wall along with range of mesangial cell proliferation and matrix expansion. Notably, the severity of lipid deposits and mesangial cell proliferation were significantly reduced in MR16-1-treated mice. Immunohistochemistry demonstrated that mesangial IL-6 expression was dramatically reduced in MR16-1-treated mice compared with IgG-treated mice. Blocking the IL-6 receptor prevented progression of proteinuria and renal lipid deposit, as well as the mesangial cell proliferation associated with severe hyperlipoproteinemia. These results clearly demonstrate that IL-6 plays an essential role in the pathogenesis of hyperlipidemia-induced glomerular injury in ApoE(-/-) mice and suggests the usefulness of anti-IL-6 receptor antibody in treatments for hyperlipidemia-induced organ damage.

Accumulation of cholesterol in the lesions of focal segmental glomerulosclerosis

Intraglomerular deposition of low-density lipoprotein (LDL) and oxidized LDL has been described in various human glomerular diseases. Yet it is not clear whether esterified cholesterol (EC) and unesterified cholesterol (UC) carried in LDL are mobilized from deposited LDL particles or accumulate in the diseased human glomeruli, particularly in the segmentally sclerotic lesions. To address this issue, frozen sections of renal biopsies were first immunostained to localize apolipoprotein B (apo B) and then oil red O (ORO) stained to colocalize neutral lipids. By using 124 ORO-positive biopsies and nine ORO-negative ones, UC was visualized directly with filipin staining, and EC was visualized after its enzymatic hydrolysis and staining with filipin. Seventy-seven biopsies (58%) showed filipin staining of accumulated EC and/or UC in the glomeruli. Of these, 11 showed heavy filipin staining for both EC and UC in the segmentally sclerotic lesions. In a group with UC deposits in the sclerotic segments, the percentage of the glomeruli affected by sclerosis and the intensity of filipin fluorescence for UC were significantly higher than biopsies with only mesangial UC deposits. Most filipin-positive biopsies showed apo B staining mainly in the mesangium. Yet in the sclerotic segments, apo B staining was rarely noted. Accumulated apo B-stained lipoprotein was not coincident with ORO-stained lipid in the diseased glomeruli. These results suggest that both EC and UC accumulate in the sclerotic glomerular segments as the glomerular lesions are advanced, and that these EC and UC appear to be derived from altered LDL with progressive loss of apo B.

Protein restriction for children with chronic renal failure

BACKGROUND

Protein restriction has been prescribed for some time for patients with chronic kidney disease (CKD). The effect of a low protein diet on delaying the progression to end-stage kidney disease (ESKD) in children and its impact on growth and nutrition remains unresolved.

OBJECTIVES

To determine the efficacy of protein restricted diet in delaying the start of maintenance dialysis and maintaining nutrition in children.

SEARCH STRATEGY

Cochrane Renal group trials register, the Cochrane Central register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, reference lists of nephrology textbooks, review articles and relevant trials.

SELECTION CRITERIA

Randomised control trials (RCTs) comparing un-restricted protein diet versus a protein restricted diet (to safe amounts recommended by WHO), with follow-up period of at least six months were included.

DATA COLLECTION AND ANALYSIS

Two authors independently selected studies. Statistical analysis were performed using the random effects model. For dichotomous outcome results are expressed as relative risk (RR) with 95% confidence intervals (CI). Where continuous scales of measurement are used to assess the effects of treatment, the mean difference (WMD) was used.

MAIN RESULTS

Two studies (250 children) were identified, 124 received a protein restricted diet and 126 a control diet. No significant differences was found in the number of renal deaths (RR 1.12, 95% CI 0.54 to 2.33), progression of kidney disease (creatinine clearance at two years: WMD 1.47, 95% CI -1.19 to 4.14) or growth (weight - WMD -0.13, 95% CI -1.10 to 0.84; height - WMD -1.99, 95% CI -4.84 to 0.86).

AUTHORS' CONCLUSIONS

Reducing protein intake does not appear to have significant impact in delaying the progression to ESKD in children.

A case of homozygous familial hypercholesterolemia with focal segmental glomerulosclerosis

Familial hypercholesterolemia (FH) is a common autosomal dominant inherited disorder characterized by increased levels of circulating plasma low-density lipoprotein cholesterol (LDL-C), tendon xanthomas, and premature atherosclerotic cardiovascular disease. Homozygous FH occurs in only one in a million people. Focal segmental glomerulosclerosis (FSGS) is clinically characterized by proteinuria, which is marked in the majority of cases and accompanied by nephrotic syndrome, high incidence of hypertension, and progression to renal failure. To our knowledge, we herein report for the first time a case of homozygous FH associated with FSGS. A seven-and-a-half-year-old boy was referred to our hospital due to cutaneous xanthomata and growth retardation. He had multiple nodular yellowish cutaneous xanthomatous lesions each 1 cm in size over his knees and sacral region. Laboratory data included cholesterol level of 1,050 mg/dl, low density lipoprotein cholesterol (LDL-C) 951 mg/dl, high-density lipoprotein cholesterol (HDL-C) 29 mg/dl, triglycerides 168 mg/dl, total protein 6.3 g/dl, and albumin 3.2 g/dl. Urinary protein excretion was 78 mg/m(2) per hour. A percutaneous renal biopsy was performed, and histological findings showed FSGS. Treatment with cholestyramine and atorvastatin was unsuccessful in terms of lowering lipids, and he was placed on weekly sessions of plasmapheresis. Total cholesterol was reduced from 1,050 mg/dl to 223 mg/dl, LDL-C from 951 mg/dl to 171 mg/dl, and urinary protein excretion from 78 mg/m(2) per hour to 42 mg/m(2) per hour after eight sessions of plasmapheresis. It is our belief that plasmapheresis is a treatment of choice in patients with FSGS associated with FH.

Clinical spectrum of chronic renal failure in the elderly: a hospital based study from eastern India

The aim of this study was to describe the clinical spectrum of chronic renal failure (CRF) in the elderly. The diagnosis of CRF was made using standard clinical criteria. The elderly was defined as person with over 60 years of age. In total, 200 elderly patients with CRF were evaluated between July 2002 and February 2004. Their age (male: 146; female: 54) ranged between 60 and 90 (mean 64.31+/-4.18) years. Diabetic nephropathy was the most common (46%) cause of CRF. Hypertensive nephrosclerosis, chronic interstitial nephritis and obstructive uropathy were responsible for CRF in 18%, 14% and 13% of patients, respectively. We observed chronic glomerulonephritis in 7% of elderly CRF. Urinary tract infection (55.5%), hypovolemia (22.2%), accelerated hypertension (11.1%) and sepsis (11.1%) were responsible for acute exacerbation of renal failure in 36 (18%) patients. Associated co-morbid conditions were noted in 93 (46.5%) patients. They included; coronary artery disease 46 (49.46%), cerebrovascular disease 20 (21.50%), osteoarthritis 13 (13.97%), chronic obstructive pulmonary disease 6 (6.45%), dilated cardiomyopathy 5 (5.37%), and malignancy in 3 (3.22%) patients. Acute dialytic support was required in 164 (82%) cases and remaining 36 (18%) patients received conservative management. Mortality was noted in 25 (12.5%) cases. The coronary artery disease (48%), acute pulmonary edema (20%) and hyperkalemia (12%) were the main causes of death. Subsequent evaluation revealed that 102 (51%) patients had ESRD of which only 3 (2.94%) patients could afford CAPD. A total of 11 (10.7%) patients underwent chronic maintenance hemodialysis for 3-4 months and then discontinue dialysis mainly because of financial constraints. Remaining 88 (86.27 %) patients with ESRD were discharged from hospital after symptomatic improvement with acute dialysis. Thus, diabetic nephropathy related to type-2 diabetes was the commonest cause of CRF in our elderly patients. Chronic renal failure in elderly was associated with a number of co-morbid conditions, which contributed significantly to morbidity and mortality. Acute on chronic renal failure with severe uremic complications were an important cause of hospitalization. The financial constraint was the major limiting factor for the management of elderly ESRD patients.

Bariatric surgery for morbid obesity: risks and benefits in chronic kidney disease patients

Obesity is one of the most preventable causes of morbidity and mortality of the 21st century. Chronic kidney disease (CKD) has been a largely overlooked consequence of obesity; however, accumulating evidence elucidates the association. Obesity is at the core, promoting a cascade of secondary pathologies including diabetes, dyslipidemia, inflammation, hypertension, and the metabolic syndrome; these comorbidities constitute great risk for CKD. With the diagnosis of CKD, there is an increased threat of cardiovascular disease and the attendant increase in morbidity and mortality rates. Substantial weight loss in the obese population can be effectively achieved and maintained through bariatric surgery, which confers major health benefits by producing resolution or improvement of obesity-related comorbidities. This surgical procedure presents an early hazard of acute on chronic kidney failure, which is offset by a potential improvement in the risk of CKD progression with anticipated improvement in hypertension, diabetes, and CKD risk factors. Future research is needed to describe the clinical course and risks and benefits of bariatric surgery in the CKD population.

Short-term administration of ACTH improves plasma lipid profile and renal function in kidney transplant patients

The present study investigated effects of short-term administration of adrenocorticotrophic hormone (ACTH) on blood lipid profile and renal function in kidney transplant patients. Six patients who had kidney transplantations 2 to 10 years earlier received ACTH intramuscularly (1 mg/d) for 4 days. We analyzed serum levels of lipids, lipoproteins, apolipoproteins, blood creatinine, and other parameters. Short-term ACTH treatment significantly decreased serum apolipoprotein B and apolipoprotein AI, whereas it significantly increased plasma high-density lipoproteins (HDL). Interestingly, creatinine level moderately decreased and creatinine clearances moderately increased among five of six patients. Hepatic function and serum concentration of cyclosporine did not change. There were no serious side effects during ACTH treatment. It was concluded that ACTH treatment had beneficial effects on serum lipoprotein profile, potentially improving renal function in kidney transplant patients. Further observations are needed to confirm these effects.

Evaluation of GFR Estimating Equations in the General Community: Implications for Screening

The Kidney Disease Outcomes Quality Initiative has recommended the use of GFR estimating equations to detect silent chronic kidney disease (CKD) in the community. The benefit of general reporting of CKD must be balanced with the harm of mislabeling people who do not have CKD. The popular Cockcroft-Gault (CG) and Modification of Diet in Renal Disease (MDRD) GFR estimating equations were compared with the recently devised Rule equation in a representative community population sample (2166) divided into subsamples with (385) and without (1781) previous renal impairment. The prevalence of CKD was CG > MDRD >> Rule estimates. The magnitude of difference in prevalence of CKD as detected by the MDRD and CG versus the Rule equation increases markedly when the subsamples with (30.8 and 29.7 versus 17.5%) and without (12 and 11.3 versus 3.0%) previous kidney impairment are compared. General demographic and potential or known risk factors were used in a logistic regression model to assess the association with CKD. The MDRD estimates note female gender (odds ratio 2.19; 95% confidence interval 1.63 to 2.95) and both MDRD and the Rule equations identify hypertension and diabetes as significant CKD risk factors. All estimating equations identify age to be associated with CKD. The annualized serial decline in GFR was CG > MDRD > Rule estimates. Only the Rule GFR estimates detected a greater decline in renal impaired versus unimpaired populations. The calibrated Rule equation seems to perform better than CG and MDRD (CKD 3 versus 11.3 to 12%) but lacks validation against gold standards for community-based screening.

Statins in nephrotic syndrome: a new weapon against tissue injury

The nephrotic syndrome is characterized by metabolic disorders leading to an increase in circulating lipoproteins levels. Hypertriglyceridemia and hypercholesterolemia in this case may depend on a reduction in triglyceride-rich lipoproteins catabolism and on an increase in hepatic synthesis of Apo B-containing lipoproteins. These alterations are the starting point of a self-maintaining mechanism, which can accelerate the progression of chronic renal failure. Indeed, hyperlipidemia can affect renal function, increase proteinuria and speed glomerulosclerosis, thus determining a higher risk of progression to dialysis. 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase is the rate-limiting enzyme in cholesterol synthesis from mevalonate and its inhibitors, or statins, can therefore interfere with the above-mentioned consequences of hyperlipidemia. Statins are already well known for their effectiveness on primary cardiovascular prevention, which cannot be explained only through their hypolipemic effect. As far as kidney diseases are concerned, statin therapy has been shown to prevent creatinine clearance decline and to slow renal function loss, particularly in case of proteinuria, and its favorable effect may depend only partially on the attenuation of hyperlipidemia. Statins may therefore confer tissue protection through lipid-independent mechanisms, which can be triggered by other mediators, such as angiotensin receptor blockers. Possible pathways for the protective action of statins, other than any hypocholesterolemic effect, are: cellular apoptosis/proliferation balance, inflammatory cytokines production, and signal transduction regulation. Statins also play a role in the regulation of the inflammatory and immune response, coagulation process, bone turnover, neovascularization, vascular tone, and arterial pressure. In this study, we would like to provide scientific evidences for the pleiotropic effects of statins, which could be the starting point for the development of new therapeutical strategies in different clinical areas.

Obesity and outcome following renal transplantation

Single institution series have demonstrated that obese patients have higher rates of wound infection and delayed graft function (DGF), but similar rates of graft survival. We used UNOS data to determine whether obesity affects outcome following renal transplantation. From the UNOS database, we identified patients who underwent primary kidney-only transplantation between 1997 and 1999. Recipient and donor body mass index (BMI) was categorized as underweight (BMI < 18.5), normal (BMI 18.5-24.9), overweight (BMI 25-29.9), obese (BMI 30-34.9) or morbidly obese (BMI > or = 35). We correlated BMI with intermediate measures of graft outcome and overall graft survival, and created multivariate models to evaluate the independent effect of BMI on graft outcome, adjusting for factors known to affect graft success. The study sample comprised 27,377 recipients. Older age, female sex, African American race and increased comorbidity were associated with obesity (p < 0.001). Compared with normal weight patients, morbid obesity was independently associated with an increased risk of DGF (p < 0.001), prolonged hospitalization (p < 0.001), acute rejection (p = 0.006) and decreased overall graft survival (p = 0.001). Donor BMI did not affect overall graft survival (p > or = 0.07). Recipient obesity is associated with an increased risk of DGF and decreased graft survival following renal transplantation.

Apolipoprotein A-IV predicts progression of chronic kidney disease: the mild to moderate kidney disease study

It has not been established firmly whether dyslipidemia contributes independently to the progression of kidney disease. Lipid and lipoprotein parameters, including levels of total, HDL, and LDL cholesterol; triglycerides; lipoprotein(a); apolipoprotein A-IV; and the apolipoprotein E and A-IV polymorphisms, were assessed in 177 patients who had mostly mild to moderate renal insufficiency and were followed prospectively for up to 7 yr. Progression of kidney disease was defined as doubling of baseline serum creatinine and/or terminal renal failure necessitating renal replacement therapy. In univariate analysis, patients who reached a progression end point (n = 65) were significantly older and had higher serum creatinine and proteinuria as well as lower GFR and hemoglobin levels. In addition, baseline apolipoprotein A-IV and triglyceride concentrations were higher and HDL cholesterol levels were lower. Multivariate Cox regression analysis revealed that baseline GFR (hazard ratio 0.714; 95% confidence interval [CI] 0.627 to 0.814 for an increment of 10 ml/min per 1.73 m(2); P < 0.0001) and serum apolipoprotein A-IV concentrations (hazard ratio 1.062; 95% CI 1.018 to 1.108 for an increment of 1 mg/dl; P = 0.006) were significant predictors of disease progression. Patients with apolipoprotein A-IV levels above the median had a significantly faster progression (P < 0.0001), and their mean follow-up time to a progression end point was 53.7 mo (95% CI 47.6 to 59.8) as compared with 70.0 mo (95% CI 64.6 to 75.4) in patients with apolipoprotein A-IV levels below the median. For the apolipoprotein E polymorphism, only the genotype epsilon2/epsilon4 was associated with an increased risk for progression. In summary, this prospective study in patients with nondiabetic primary kidney disease demonstrated that apolipoprotein A-IV concentration is a novel independent predictor of progression.

Acute inhibition of the endogenous xanthine oxidase improves renal hemodynamics in hypercholesterolemic pigs

Hypercholesterolemia (HC), a major risk factor for onset and progression of renal disease, is associated with increased oxidative stress, potentially causing endothelial dysfunction. One of the sources of superoxide anion is xanthine oxidase (XO), but its contribution to renal endothelial function in HC remains unclear. We tested the hypothesis that XO modulates renal hemodynamics and endothelial function in HC pigs. Four groups (n = 23) of female domestic pigs were studied 12 wk after either normal (n = 11) or HC diet (n = 12). Oxidative stress was assessed by plasma isoprostanes and oxidized LDL, and the XO system by plasma uric acid, urinary xanthine, and renal XO expression (by immunoblotting and immunohistochemistry). Renal hemodynamics and function were studied with electron beam-computed tomography before and after endothelium-dependent (ACh) and -independent (sodium nitroprusside) challenge, during a concurrent intrarenal infusion of either oxypurinol or saline (n = 5-6 in each group). HC showed elevated oxidative stress, higher plasma uric acid (23.8 +/- 3.8 vs. 6.2 +/- 0.8 microM/mM creatinine, P = 0.001), lower urinary xanthine, and greater renal XO expression compared with normal. Inhibition of XO in HC significantly improved the blunted responses to ACh of cortical perfusion (13.5 +/- 12.1 and 37.2 +/- 10.6%, P = 0.01 and P = not significant vs. baseline, respectively), renal blood flow, and glomerular filtration rate; restored medullary perfusion; and improved the blunted cortical perfusion response to sodium nitroprusside. This study demonstrates that the endogenous XO system is activated in swine HC. Furthermore, it suggests an important role for XO in regulation of renal hemodynamics, function, and endothelial function in experimental HC.

Oxidized LDL activates PAI-1 transcription through autocrine activation of TGF-beta signaling in mesangial cells

BACKGROUND

Lipid abnormalities and oxidative stress may be involved in the development of glomerulosclerosis. Plasminogen activator inhibitor-1 (PAI-1) is a component of extracellular matrix (ECM) and target gene of transforming growth factor-beta (TGF-beta). Smad proteins play a key role in TGF-beta signaling, and Smad binding CAGA boxes are present in the PAI-1 promoter. This study examined whether oxidized low-density lipoprotein (Ox-LDL) activates PAI-1 transcription in human mesangial cells, mediated by increased Smad/DNA interactions.

METHODS

Quiescent HMC were incubated with 50 microg/mL of Cu(++)-catalyzed Ox-LDL for 15 minutes to 4 hours, and the effects of Ox-LDL on TGF-beta1 and PAI-1 mRNA expression, PAI-1 promoter activity, and DNA binding activity of Smad proteins were examined.

RESULTS

Ox-LDL induced TGF-beta1 and PAI-1 mRNA expression. Ox-LDL increased the transiently transfected PAI-1 promoter activity as compared with controls to 3.9-fold. Ox-LDL-treated cells increased Smad3 protein levels two times the control levels in the nuclei. Electrophoretic mobility shift assay (EMSA) performed using a CAGA sequence probe and nuclear extracts showed that Ox-LDL increased DNA/protein complexes. When nuclear extracts were preincubated with 100 molar excess of unlabeled CAGA oligonucleotide or SB-431542, an inhibitor of the TGF-beta type I receptor, the formation of complex was prevented. The DNA binding protein was shown to be Smad3 by antibody supershift. Transfection of phosphorothioate CAGA oligonucleotides, which compete with the CAGA-containing PAI-1 promoter for Smad3 binding, inhibited the Ox-LDL-induced PAI-1 mRNA expression. Cotransfection of phosphorothioate CAGA oligonucleotides with PAI-1 reporter vector also blocked the Ox-LDL-induced PAI-1 promoter activity.

CONCLUSION

These results suggest that Ox-LDL activates TGF-beta/Smad signaling to stimulate PAI-1 transcription in human mesangial cells. Thus, progression of glomerular disease may be promoted by PAI-1 up-regulation in human mesangial cells mediated by the Ox-LDL-induced TGF-beta/Smad signaling pathways.

Dyslipidemias in patients who have chronic kidney disease

Patients with CKD are at high risk for developing CVD. In fact, most CKD patients have a 10-year risk of coronary heart disease events greater than or equal to 20%, placing them in the highest risk category according to the National Cholesterol Education Program Adult Treatment Panel III guidelines. For this reason, the National Kidney Foundation K/DOQI guidelines for managing dyslipidemia suggest that CKD patients with LDL greater than or equal to 100 mg/dL (2.59 mmol/L) should be treated with diet and a statin. The K/DOQI guidelines also make it clear that the evidence supporting treatment in CKD populations is lacking however, and that additional placebo-controlled trials are needed. In the mean time, the high incidence of CVD makes intensive monitoring and treatment of dyslipidemias in patients with CKD a reasonable clinical approach.

Effects of statin therapy on the progression of chronic kidney disease

Statins are lipid-lowering agents that specifically, competitively, and reversibly inhibit 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the enzyme that catalyzes the conversion of HMG-CoA to mevalonic acid, the rate-limiting step in the formation of cholesterol. A large body of evidence from numerous, well-controlled, randomized trials demonstrates that statins significantly reduce fatal and nonfatal cardiovascular events in the general population. Cardiovascular benefits of statins have been conventionally attributed to reduction in levels of low-density lipoprotein cholesterol. More recently, subanalyses of large clinical trials suggest that statins may also prove beneficial in ameliorating the progression of kidney disease through their cholesterol-dependent and/or cholesterol-independent (pleiotropic) effects. This review focuses on the role of statin therapy in the progression of chronic kidney disease, the published trials that study the effect of antilipidemic agents on nephropathy, and the emerging pleiotropic effects of statins on the kidneys.

Salubrious effect of low molecular weight heparin on atherogenic diet-induced cardiac, hepatic and renal lipid peroxidation and collapse of antioxidant defences

The present work showcases the distressing picture of oxidative stress in the cardiac, hepatic and renal tissues, in an experimental model based on early phase atherogenesis. The protection rendered by LMWH intervention forms part of the same study. Male Wistar rats of 140 +/- 10 g were categorized as four groups. One group served as untreated control and another as LMWH drug control group. Two groups were fed a hypercholesterolemic atherogenic diet (rat chow supplemented with 4% cholesterol, 1% cholic acid and 0.5% thiouracil; CCT diet) for 2 weeks; one of these groups received LMWH treatment of 300 microg/day/rat for 7 days. The biochemical index of tissue lipid peroxidation (LPO) was assessed in terms of MDA formation. Heart, liver and kidney tissues of CCT-diet fed rats showed significantly elevated levels of LPO. In the early phase atherosclerotic group, we observed abnormal changes in the activities/levels of tissue enzymic (superoxide dismutase, catalase and glutathione peroxidase) and non-enzymic (reduced glutathione, ascorbate and alpha-tocopherol) antioxidants. We report normalized LPO levels and antioxidant defences in the atherogenic rats treated with LMWH. Thus the present study highlights the hepatic, cardiac and renal oxidative changes induced by experimental atherogenesis, and the protection rendered by LMWH treatment in atherosclerotic cardiovascular conditions.

Oral supplement of six selective amino acids arrest progression renal failure in uremic patients

Certain amino acids such as glycine, L-aspartic acid, L-glutamic acid, L-glutamine, L-histidine and L-arginine taken orally by normal adults or patients with renal failure increase glomerular filtration rate (GFR). Twelve nondiabetic patients suffering from glomerulonephritis confirmed by renal biopsy previously, with creatinine clearances ranging from 15 to 24 ml minute/1.73, and on low protein diet 0.6 g/ kg/day, received an amino acid supplement daily in 2 or 3 doses for 1 year. At 4, 8 and 12 months creatinine clearance increased slightly (NS, NS, NS), 24 hour urine volume increased (P < or = 0.001, 001, 0.001), 24 hour albuminuria decreased (P < 0.001, 0.001, 0.001), serum urea increased (NS, NS, NS) serum albumin increased (NS, 0.05, 0.05), total cholesterol decreased slightly (NS, NS, 0.01), HDL increased slightly (0.05, 0.05, 0.05), LDL decreased (NS, 0.001, 0.001) triglycerides decreased (0.001, 0.001, 0.001), Apo B remained unchanged (NS, NS, NS), ROS/H2O2 decreased (0.001, 0,001, 0.001), Hct increased (NS, 0.01, 0.01) Hb increased (0.05, 0.05, 0.05), and serum phosphate decreased (0.01, 0.01, 0.01). After removal of supplements at the end of the year all parameters remained unchanged. We believe that a large controlled study should be undertaken to confirm these most encouraging findings.

Proteinuria and its consequences in renal disease

Chronic renal diseases that involve proteinuria are typically characterized by an inexorable progression to end-stage renal failure. Many studies suggest that this progression may be the result of factors, such as intraglomerular hypertension and glomerular hypertrophy, that are unrelated to the initial disease. This paper reviews the mechanisms of progression of chronic renal diseases and discusses therapeutic strategies that should prevent or minimize further renal damage and the applicability of these strategies to patients with the rare X-linked lysosomal storage disorder Fabry disease. Renal involvement is a major feature of Fabry disease, which is characterized by vacuolated epithelial cells in the glomerulus and distal tubules, resulting from lipid inclusions within these cells. Although enzyme replacement therapy is the key strategy to halt the progression of Fabry disease, additional therapeutic options include blood pressure control, reduction of proteinuria, lipid control and inhibition of the renin-angiotensin system.

CONCLUSION

A range of therapeutic options, used in conjunction with enzyme replacement therapy, may have beneficial effects on the renal manifestations of Fabry disease.

Oxidized LDL induces transcription factor activator protein-1 in rat mesangial cells

It has been shown that oxidized low-density lipoprotein (ox-LDL), through the activation of glomerular cells, stimulates pathobiological processes involved in monocyte infiltration into the mesangium. The underlying molecular mechanisms are not fully understood. The present study showed that ox-LDL strongly induced AP-1 binding activity in rat mesangial cells (RMCs) in a dose- and time-dependent manner, reaching the maximal activation at 250 microg ml(-1) within 24 h. The results from mobility shift assays and Western blotting analysis revealed that this AP-1 binding increase involved c-Jun, but not c-Fos. Moreover, this ox-LDL-increased AP-1 binding was inhibited by several protein kinase (PK) inhibitors: the protein kinase C (PKC) inhibitor Bisindolylmaleimide I, the cAMP-dependent PK (PKA) inhibitor H89, and the tyrosine PK (PTK) inhibitor genistein. Protein phosphorylation represents mitogen-activated protein kinase (MAPK) activity. Therefore, we examined the role of ox-LDL on the activation of mesangial cell JNK/SAPK, the only recognized protein kinase that catalyses phosphorylation of c-Jun. The incubation of mesangial cells with ox-LDL induced phosphorylation of JNK1/SAPK dose dependently, with the maximal response at 150 microg ml(-1). This study demonstrates that multiple kinase activities are involved in the mechanism of ox-LDL-induced AP-1 activation in mesangial cells, and ox-LDL stimulates AP-1 through JNK-c-Jun other than MEK-c-Fos signalling pathway.

Cholesterol and the risk of renal dysfunction in apparently healthy men

Despite extensive knowledge about abnormal lipid patterns in patients with end-stage renal disease, the association between cholesterol and the development of renal dysfunction is unclear. We evaluated this association in a prospective cohort study among 4,483 initially healthy men participating in the Physicians' Health Study who provided blood samples in 1982 and 1996. Main outcome measures were elevated creatinine, defined as >/= 1.5 mg/dl (133 micromol/L), and reduced estimated creatinine clearance, defined as </=55 ml/min. Cholesterol parameters included total cholesterol (<200, 200 to 239, and >/= 240 mg/dl), HDL (<40 or >/= 40 mg/dl), total non-HDL cholesterol, and the ratio of total cholesterol to HDL. We used logistic regression to calculate age- and multivariable adjusted odds ratios as a measure for the relative risk. After 14 yr, 134 men (3.0%) had elevated creatinine and 244 (5.4%) had reduced creatinine clearance. The multivariable relative risk for elevated creatinine was 1.77 (95% confidence interval [CI], 1.10 to 2.86) for total cholesterol >/= 240 mg/dl, 2.16 (95% CI, 1.42 to 3.27) for HDL <40 mg/dl, 2.34 (95% CI, 1.34 to 4.07) for the highest quartile of total cholesterol/HDL ratio (>/= >6.8), and 2.16 (95% CI, 1.22 to 3.80) for the highest quartile of non-HDL cholesterol (>/= 196.1). Similar although smaller associations were observed between cholesterol parameters and reduced creatinine clearance. Elevated total cholesterol, high non-HDL cholesterol, a high ratio of total cholesterol/HDL, and low HDL in particular were significantly associated with an increased risk of developing renal dysfunction in men with an initial creatinine <1.5 mg/dl.