Lipids and progressive glomerulosclerosis. A model analogous to atherosclerosis

Association between remnant cholesterol level and severity of chronic kidney disease in patients with type 2 diabetes

BACKGROUND

Studies on whether remnant cholesterol (RC) affects the progression of chronic kidney disease (CKD) remain insufficient. This study aimed to determine whether RC level was associated with the severity of CKD in patients with type 2 diabetes mellitus (T2DM).

METHODS

In total, 3383 individuals diagnosed with T2DM were enrolled in this cross-sectional study from China. The severity of CKD was defined as no, moderate, severe, and very severe CKD based on the urinary albumin-to-creatinine ratio and estimated glomerular filtration rate. Because RC was non-normally distributed, it was log-transformed and categorized into quantiles. Multivariate logistic regression and multivariate ordinal logistic regression analysis were performed to investigate whether RC was independently associated with CKD and its severity.

RESULTS

The median RC level was 25.9 mg/dL. The number of patients with no, moderate, severe, and very severe CKD was 2587 (76.5 %), 520 (15.4 %), 189 (5.6 %), and 87 (2.5 %), respectively. After adjusting for confounding factors, the prevalence of CKD increased 1.67-fold when the log-transformed RC level was elevated by one unit (OR [95 % CI], 1.67 [1.43-1.95]). The likelihood of CKD severity increasing by one degree was 1.76-fold for each one-unit increase in log-transformed RC level (OR [95 % CI], 1.76 [1.52-2.05]). When RC was incorporated as a categorical variable, it still correlated with CKD severity compared with quantile 1 (Q1) (Q2, 1.30 [1.01-1.68]; Q3, 1.60 [1.23-2.07]; Q4, 2.39 [1.86-3.09]). The association remained regardless of whether the patient's traditional lipid profiles achieved the target range.

CONCLUSION

RC level was associated with CKD severity even when traditional lipid profiles were within the target range in patients with T2DM.

Association between changes in lipid indexes and early progression of kidney dysfunction in participants with normal estimated glomerular filtration rate: a prospective cohort study

PURPOSE

To investigate whether non-high-density lipoprotein cholesterol (Non-HDL-C), remnant cholesterol (RC), and the ratios of lipid indexes are more closely associated with early progression of kidney dysfunction than traditional lipid indexes; and to explore the association between changes in serum lipids during follow-up and annual decline rate in estimated glomerular filtration rate (eGFR).

METHODS

In this prospective cohort study, 3909 participants with normal eGFR and age≥40 years at baseline were followed for 3.3 years. Progression of kidney dysfunction was assessed as annual decline rate in eGFR. Spearman correlation analysis, linear correlation models, and multiple logistic regression were used to assess the associations between lipid indexes at baseline/both baseline and follow-up and the annual decline rate in eGFR.

RESULTS

Compared with ΔLDL-C (β = 0.412), other lipid indexes such as ΔLDL-C/HDL-C (β = 0.565), ΔTC/HDL-C (β = 0.448), and ΔNon-HDL-C/HDL-C (β = 0.448) were more closely associated with annual decline rate in eGFR. High TG/HDL-C (OR = 1.699(1.177-2.454)) and TC/HDL-C (OR = 1.567(1.095-2.243)) at baseline, as well as high TC/HDL-C (OR = 1.478 (1.003-2.177)) and TG/HDL-C (OR = 1.53(1.044-2.244)) at both baseline and follow-up were associated with the annual decline rate in eGFR <0.5. High Non-HDL-C (OR = 1.633(1.025-2.602)) and LCI (OR = 1.631(1.010-2.416)) at both baseline and follow-up resulted in a 63% increase in risk of annual decline rate in eGFR >1.

CONCLUSION

High Non-HDL-C, RC and the ratios of lipid indexes were more closely associated with early progression of kidney injury than the increase of traditional lipid indexes. These lipid indexes should be monitored, even in participants with normal traditional serum lipid levels.

The relationship between lipid risk score and new-onset hypertension in a prospective cohort study

BACKGROUND

Dyslipidemia and hypertension are both important risk factors for atherosclerotic cardiovascular diseases. However, the relationship between dyslipidemia and incident hypertension remains to be elucidated comprehensively. The main purpose of this study was to construct the lipid risk score to explore the risk prediction effect of integrated lipid indices on new-onset hypertension.

METHODS

This prospective cohort study with 2116 non-hypertensive subjects was conducted from 2009 to 2020. New hypertension events during the follow-up period were recorded and verified. The lipid risk score was calculated by summing coded total cholesterol, triglyceride, low-density lipoprotein cholesterol, and high-density lipoprotein cholesterol weighted with corresponding effect sizes. Cox regression analysis was used to estimate the association between the lipid risk score or lipid indices and incident hypertension in the subgroup of age (< 55 and≥ 55 years at baseline).

RESULTS

After a median of 10.75-year follow-up, 637 incident hypertension cases were identified. The restricted cubic spline showed that the lipid risk score had a positive linear correlation with hypertension (P< 0.001). Among people< 55 years, with every increase of 0.94 in lipid risk score, the risk of hypertension increased by 37% (adjusted HR [95%CI]: 1.369 [1.164-1.610]). This association was not modified by overweight or obesity.

CONCLUSIONS

The integrated lipid risk score, independent of traditional risk factors, has a significantly predictive effect on hypertension in people younger than 55 years. This finding may aid in identifying high-risk individuals for hypertension, as well as facilitating early intervention and management to reduce adverse cardiovascular events. Comprehensive lipid management should be attached importance in the prevention and control of hypertension.

Hypertriglyceridemia Is Associated with More Severe Histological Glomerulosclerosis in IgA Nephropathy

IgA nephropathy (IgAN) is a globally well-known primary glomerular nephropathy. Hypertriglyceridemia (HTG) is one factor contributing to atherosclerosis and is a common complication of renal failure. HTG is a significant risk factor for decreased renal function in patients with IgAN. We evaluated the association of HTG with the histopathological features of IgAN patients. A total of 480 patients diagnosed with IgAN via kidney biopsy from eight university hospitals affiliated with the College of Medicine of the Catholic University of Korea were included in the final cohort. Pathological features were evaluated by eight expert pathologists with hospital consensus. HTG was defined as a serum triglyceride (TG) level of ≥150 mg/dL. In the study population analysis, the HTG group was older, with more males; higher body mass index (BMI), low-density lipoprotein cholesterol (LDL-C) and spot urine protein ratio; and lower estimated glomerular filtration rate (eGFR). In the lipid profile analysis, eGFR was negatively correlated with TGs/ high-density lipoprotein cholesterol (HDL) and triglyceride-glucose index (TyG). Proteinuria positively correlated with TGs/HDL, non-HDL/HDL, LDL/HDL, TyG, TGs and LDL. The percentages of global sclerosis (GS), segmental sclerosis (SS) and capsular adhesion (CA), and the scores for mesangial matrix expansion (MME) and mesangial cell proliferation (MCP), were more elevated in the HTG group compared to the normal TG group. Multivariable linear regression analysis showed that the percentages of global sclerosis, segmental sclerosis and capsular adhesion, as well as the scores for mesangial matrix expansion and mesangial cell proliferation, were positively associated with TG level. In binary logistic regression, the HTG group showed a higher risk for global sclerosis and segmental sclerosis. In conclusion, HTG is a significant risk factor for glomerulosclerosis in IgAN.

Association of the long fluoroscopy time with factors in contemporary primary percutaneous coronary interventions

BACKGROUND

Since the long fluoroscopy time in primary PCI for ST-segment elevation myocardial infarction (STEMI) could be an indicator of delayed reperfusion, it should be important to recognize which types of lesions require longer fluoroscopy-time in primary PCI. The purpose of this study was to investigate the association of the long fluoroscopy-time with clinical factors in primary percutaneous coronary interventions (PCI).

METHODS

A total of 539 patients who underwent primary PCI were divided into the conventional fluoroscopy-time group (Q1-Q4: n = 434) and the long fluoroscopy-time group (Q5: n = 105) according to the quintile of the total fluoroscopy time in primary PCI. Univariate and multivariate logistic regression analyses were performed to find associations between clinical variables and the long fluoroscopy-time.

RESULTS

In univariate logistic regression analysis, prevalence of diabetes mellitus, hemodialysis, and previous CABG were significantly associated with the long fluoroscopy-time. In addition, complex lesion characteristics such as lesion length, lesion angle, tortuosity, and calcification were associated with the long fluoroscopy-time. In multivariable logistic regression analysis, lesion length [per 10 mm incremental: odds ratio (OR) 1.751, 95% confidence interval (CI) 1.397-2.195, P<0.001], moderate-excessive tortuosity (vs. mild tortuosity: OR 4.006, 95% CI 1.498-10.715, P = 0.006), and moderate to severe calcification (vs. none-mild calcification: OR 1.865, 95% CI 1.107-3.140, P = 0.019) were significantly associated with the long fluoroscopy-time.

CONCLUSIONS

In primary PCI for STEMI, diffuse long lesion, tortuosity, and moderate-severe calcification were associated with the long fluoroscopy-time. These complex features require special attention to reduce reperfusion time in primary PCI.

Ibrolipim attenuates early-stage nephropathy in diet-induced diabetic minipigs: Focus on oxidative stress and fibrogenesis

It is well-recognized that hyperlipidemia and lipid peroxidation contribute to the progression of diabetic nephropathy (DN), which is associated with oxidative stress (OS) and fibrotic lesions. Ibrolipim, a specific lipoprotein lipase activator, has been proved to reduce hyperglycemia and hyperlipidemia, suppress renal lipid deposition, and also protect renal damage. However, the underlying mechanisms of its renoprotective effect are not clearly elaborated. Herein, the present study was to identify whether the putative mechanism of Ibrolipim was related to OS and fibrogenesis in diabetic minipigs fed by high-sucrose and high-fat diet (HSFD) with or without Ibrolipim for 5 months. Compared with the normal control diet, nutrient stress induced by HSFD caused moderate glomerulosclerosis and tubulointerstitial fibrosis, and promoted renal ultrastructural and functional abnormalities. These abnormalities were correlated with renal OS and fibrogenesis characterized by the increased levels of reactive oxygen species (ROS), malondialdehyde, hydroxyproline, collagen type Ⅳ alpha 1 and fibronectin, and decreased contents of reduced glutathione and total antioxidant capacity in kidneys. Ibrolipim significantly ameliorated these abnormalities in HSFD-fed minipigs. In addition, Ibrolipim diminished HSFD-induced nicotinamide-adenine dinucleotide phosphate oxidase-4 activation to reduce ROS production, and enhanced the expression and activity of antioxidant enzymes (i.e. superoxide dismutase 1, catalase and glutathione peroxidase 1) to increase ROS elimination, resulting in obvious suppression of renal OS. Meanwhile, Ibrolipim not only inhibited the upregulation of transforming growth factor-β1 but also partially reversed the downregulation of matrix metalloproteinase 2, and then prevented extracellular matrix (ECM) accumulation. Taken together, Ibrolipim exhibits anti-oxidative and anti-fibrotic effects via modulating the rebalance of renal ROS and ECM metabolism, and ultimately attenuates the progression of nephropathy in diet-induced diabetic minipigs.

Apolipoprotein E and plasminogen activator inhibitor 1 gene polymorphism in children with chronic renal insufficiency associated with cardiovascular disease

Background

Cardiovascular disease (CVD) is considered a major cause of death in renal insufficiency (RI). Contributing genetic factors is a recent focus of research. This study aims to elucidate apolipoprotein E (APO-E) and plasminogen activator inhibitor 1 (PAI-1) gene polymorphisms in RI children associated with CVD.

Methods

We studied 50 cases with chronic kidney disease (CKD) associated with CVD, and 30 healthy controls. Study sample was grouped as one on conservative treatment, the second on hemodialysis and the third was posttransplant. PAI-1 and APO-E gene polymorphisms were investigated using allele-specific polymerase chain reaction (AS-PCR) and polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) respectively.

Results

4G4G and 4G5G were the most common PAI-1 polymorphism denoting high association of 4 G allele in renal insufficiency associated with CVD with absent link to dyslipidemia, echocardiography changes or thrombosis. E3E3 was the most common among APO-E polymorphism without relation to dyslipidemia or thrombosis. Dyslipidemia was significantly linked to thrombosis. The study confirmed the role of dyslipidemia and hemodialysis in promoting thrombosis.

Conclusion

Although PAI 4G Genotyping did not show significant association with echocardiography severity or thrombotic severity, yet genetic expression for high levels of PAI in plasma is expected in response to CRI factors known to trigger its release, in addition to those related to dialysis. APO-E3E3 genotyping showed a significant association with echocardiography severity as it enhances APO-A which contributes to CVD. The current study confirmed a significant association between dyslipidemia and CVD; however, the prevalent patterns 4G and E3E3 did not show a significant association with dyslipidemia. The genetic role for APO-A, B, O, or even other isomers for APO-E should be further studied as well.

Synergistic action of inflammation and lipid dysmetabolism on kidney damage in rats

In kidney disease, inflammation and lipid dysmetabolism are often associated together, however, the effect and mechanism of inflammatory mediators and lipid dysmetabolism on kidney damage is still unclear. In this study, Wistar rats were randomized into four groups: normal diet + saline (Group N), high-fat diet (HF)+ saline (Group HF), normal diet + adriamycin (Group ADR), HF + adriamycin (Group ADR + HF). After 10 weeks of feeding, rats in each group were randomly sacrificed. We found that the protein content of urine in ADR and ADR + HF groups were significantly higher than that of group N and HF while the serum levels of total protein and albumin in the ADR and ADR + HF groups decreased correspondingly. The serum levels of triglyceride, total cholesterol and low-density lipoprotein in the HF, ADR and ADR + HF groups increased. In the treatment groups, mesangial proliferation, matrix accumulation, tubular vacuolization, inflammatory cell infiltration and fat deposition were detected. These pathological changes were the most serious in the ADR + HF group. The expression of tumor necrosis factor-α (TNF-α) and transforming growth factor-β1 (TGF-β1) were increased in each treatment group, especially in the ADR + HF group. Our results suggested that the inflammatory factors and abnormal lipid levels can activate the inflammatory response in kidney of the Wistar rats, and lead to a series of pathological changes in renal tissue, and inflammatory factors and lipid dysmetabolism can aggravate damage in the kidney.

Effects of dietary therapy on post renal transplant hyperlipidemia. A prospective study

Hyperlipidemia often occurs after renal transplantation and may contribute to increased cardiovascular morbidity. The National cholesterol education program guidelines (NCEP) recommend dietary modification as the initial therapeutic intervention. We evaluated the effects of the AHA Step I and Step II diets on the serum total cholesterol (TC) and the triglyceride (TG) levels in nondiabetic renal transplant patients. Both the AHA Step I (TC 296 ± 7 vs 294 ± 9 mg/dL, p = ns) and Step II diets (TC 282 ± 8 vs 292 ± 16 mg/dL, p = ns) failed to significantly lower the serum total cholesterol and the triglycerides levels. During this dietary intervention, the patients' body weight and serum creatinine level remained stable. Our data suggest that neither the AHA Step 1 nor the Step II diet are effective in significantly lowering elevated serum lipids in nondiabetic renal transplant recipients.

Characteristics of the Lipid Profile in Patients with Diabetes Mellitus and Chronic Kidney Disease

Background and aims Diabetes mellitus (DM) is one of the leading causes of end-stage chronic kidney disease (CKD). Patients with DM and CKD have a 10 or even 20 times higher cardiovascular risk (CVR) than the general population. Lipid metabolism disorders are more frequent in these patients, dyslipidemia being aggravated by the presence of hyperglycemia and insulin resistance. The main purpose of our study was to identify possible correlations between lipid profile parameters and altered renal function in patients with DM. We have also analyzed the correlations between lipid parameters, CKD, quality of glycemic control and CVR.

Material and method: The study was performed on 2732 patients with DM which received medical treatment and care at the Center for Diabetes Timisoara, for a 6-month period from March to October 2016, 1508 women (55.2%) and 1224 men (44.8%), mean age 63.7 ± 9.1 (33-78) years and mean diabetes duration 12.4 ± 6.8 (6-33) years. The study group included 312 patients (11.4%) with T1DM and 2420 patients (88.6%) with T2DM.

Results: The prevalence of CKD (GFR< 60 ml/min) was 12.5%. The levels of total cholesterol (TC), triglycerides (TG) and LDLc were significantly higher in the case of patients with DM and CKD (p<0.0001). Patients with CKD had twice the prevalence of ischemic heart disease and cerebrovascular disease when compared to patients without CKD. Peripheral artery disease was present in 16.9% of those with CKD and in 11% of those without CKD. Hypertension (HTN) was present in 91.8% of patients with CKD and in 67.1% of patients without CKD (GFR > 60 ml/min).

Conclusion: Analyzed data showed a strong correlation between CKD, dyslipidemia and CVR in patients with DM. Impaired renal function was strongly correlated with age, duration of DM and weight status of these patients.

CD40-Dependent Activation of Phosphatidylinositol 3-Kinase/Akt Pathway Inhibits Apoptosis of Human Cultured Mesangial Cells Induced by Oxidized LDL

Deposition of atherogenic lipoproteins is associated with various glomerular diseases. In particular, oxidized LDL (oxLDL) may affect mesangial cells and favour the development of glomerulosclerosis. The aim of the present study was to investigate on cultured human mesangial cells (HMC) whether oxLDL induces apoptosis by a mechanism dependent on the inhibition of Akt survival pathway, and whether the engagement of mesangial CD40 by its ligand CD154 inhibits the apoptotic effect of oxLDL. Tunel assays demonstrated that incubation of HMC for 24h with oxLDL, but not with unmodified LDL, induced a dose-dependent increase in apoptosis of HMC associated with a decrease in Akt phosphorylation. Enzymatic kinase assay showed that also the Akt activity was reduced in a dose-dependent manner by treatment with oxLDL. Stimulation of mesangial CD40 with sCD154 rescued HMC from oxLDL-dependent apoptosis, while two unrelated pharmacological inhibitors of PI3K LY294002 and wortmannin abrogated this anti-apoptotic effect, suggesting an involvement of the PI3K/Akt pathway. Moreover CD40 stimulation maintained an elevated phosphorylation of Akt and preserved its enzymatic activity in the presence of oxLDL. Indeed, CD154 induced a rapid enhancement in Akt enzymatic activity, that was temporarily correlated with the association of CD40 with TRAF3, TRAF6, c-Cbl and the p85 subunit of PI3K. In conclusion, these results suggest that CD40 stimulation protects HMC from toxic effects of oxLDL by promoting PI3K/Akt-dependent cell survival.

Inflammatory Stress Exacerbated Mesangial Foam Cell Formation and Renal Injury via Disrupting Cellular Cholesterol Homeostasis

Inflammation and lipids play significant roles in the progression of chronic kidney disease. This study was designed to investigate whether inflammation disrupts cellular cholesterol homeostasis and causes the lipid nephrotoxicity in vitro and in vivo, and explored its underlying mechanisms. Inflammatory stress was induced by cytokines (interleukin-1β (IL-1β); tumor necrosis factor α (TNF-α)) to human mesangial cells (HMCs) in vitro and by subcutaneous casein injection in C57BL/6J mice in vivo. The data showed that inflammatory stress exacerbated renal cholesterol ester accumulation in vitro and in vivo. Inflammation increased cellular cholesterol uptake and synthesis via upregulating the expression of low-density lipoprotein receptor (LDLr) and 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCoA-R), while it decreased cholesterol efflux via downregulating the expression of liver X receptor alpha and ATP-binding cassette transporter A1. The increased lipid accumulation by inflammatory stress induced reactive oxygen species (ROS) and increased levels of endoplasmic reticulum (ER) stress markers (inositol-requiring protein 1 and activating transcription factor 6) in HMCs and kidneys of C57BL/6J mice. This study implied that inflammation promoted renal lipid accumulation and foam cell formation by disrupting cellular cholesterol homeostasis. Increased intracellular lipids under inflammatory stress caused oxidative stress and ER stress in vitro and in vivo which may contribute to renal injury and progression of chronic kidney disease.

Paraoxnase1 Gene Polymorphism in Childhood Idiopathic Nephrotic Syndrome

BACKGROUND

Paraoxonase1 (PON1) is a serum enzyme bound to high-density lipoproteins with antioxidant properties. Molecular studies of PON1 revealed 2 polymorphic sites at amino acids 55 and 192 resulting in 2 different allozymes, the L and M-genotype at residue 55 and A and B at site 192, respectively. We have studied the association between PON1 gene polymorphisms and the minimal change nephrotic syndrome/focal segmental glomerulosclerosis (MCNS/FSGS) types of idiopathic nephrotic syndrome (INS) in Kuwaiti Arab children.

METHODS

The PON1 gene, 55 and 192 polymorphisms were analyzed in 50 children with INS (32 MSCN, 18 FSGS) and compared to 50 controls. Serum creatinine, albumin and lipids were measured in all subjects.

RESULTS

The LL genotype was detected in 50% of the INS patients compared to 48% of controls (p = 0.84). The heterozygous LM genotype was detected in 42% of INS patients compared 36% of controls (p = 0.68). The MM-genotype was detected in 8% of INS patients and 16% of controls (p = 0.35). The L-allele frequency in its homozygous and heterozygous forms was found in 71% of INS patients compared to 66% controls (p = 0.54). The L-allele frequency (LM and LL) was significantly higher in FSGS compared to MCNS patients (p = 0.0001) and when compared to controls (p = 0.0007). All patients and controls had the AA form of the 192 PON1 gene polymorphism.

CONCLUSION

Our data demonstrate a strong association between the L-allele of PON1 gene 55 polymorphism with FSGS in Kuwaiti Arab children with INS. PON1 genotyping can help in the early prediction of FSGS, which might guide clinicians to a better therapeutic approach.

Association between Helicobacter pylori infection and the subsequent risk of end-stage renal disease: a nationwide population-based cohort study

BACKGROUND & AIMS

The association between Helicobacter pylori infection and end-stage renal disease (ESRD) events remains unknown. We assessed the relationship between H. pylori infection requiring hospital admission and the subsequent risks of ESRD.

METHODS

This was a retrospective cohort study in which data from the National Health Insurance system of Taiwan was used. The H. pylori-infected cohort comprised 20,068 patients. Each participant was frequency-matched by age and sex with 4 individuals from the general population without H. pylori-infected. Cox proportional hazards regression analysis was used to estimate the influence of H. pylori infection on the risk of ESRD.

RESULTS

The overall incidence of ESRD was 3.72 times greater in the H. pylori-infected cohort than in the non-infected cohort (11.1 vs. 2.96 per 1000 person-years), with an adjusted HR of 2.58 [95% confidence interval (CI)=2.33-2.86]. The risk of ESRD markedly increased in patients with H. pylori infection combined with at least one of the following concomitant comorbidities: hypertension, diabetes, hyperlipidaemia and coronary artery disease.

CONCLUSIONS

This is currently the largest nation-based study in which the risk of ESRD in H. pylori-infected patients was examined. H. pylori infection was associated with a subsequent risk of ESRD. H. pylori-infected patients with concomitant chronic kidney disease (CKD) or cardiovascular disease (CVD) risk factors were at higher risk of ESRD than were those who had a single CKD or CVD risk factor.

Genetic analysis of intracapillary glomerular lipoprotein deposits in aging mice

BACKGROUND

Renal aging is characterized by functional and structural changes like decreased glomerular filtration rate, and glomerular, tubular and interstitial damage. To gain insight in pathways involved in renal aging, we studied aged mouse strains and used genetic analysis to identify genes associated with aging phenotypes.

METHODS

Upon morphological screening in kidneys from 20-month-old mice from 26 inbred strains we noted intracapillary PAS-positive deposits. The severity of these deposits was quantified by scoring of a total of 50 glomeruli per section (grade 0-4). Electron microscopy and immunohistochemical staining for apoE, apoB, apoA-IV and perilipin-2 was performed to further characterize the lesions. To identify loci associated with these PAS-positive intracapillary glomerular deposits, we performed haplotype association mapping.

RESULTS

Six out of 26 mouse strains showed glomerular PAS-positive deposits. The severity of these deposits varied: NOD(0.97), NZW(0.41), NON(0.30), B10(0.21), C3 H(0.9) and C57BR(0.7). The intracapillary deposits were strongly positive for apoE and weakly positive for apoB and apoA-IV. Haplotype association mapping showed a strong association with a 30-Kb haplotype block on Chr 1 within the Esrrg gene. We investigated 1 Mb on each site of this region, which includes the genes Spata17, Gpatch2, Esrrg, Ush2a and Kctd3.

CONCLUSIONS

By analyzing 26 aged mouse strains we found that some strains developed an intracapillary PAS and apoE-positive lesion and identified a small haplotype block on Chr 1 within the Esrrg gene to be associated with these lipoprotein deposits. The region spanning this haplotype block contains the genes Spata17, Gpatch2, Esrrg, Ush2a and Kctd3, which are all highly expressed in the kidney. Esrrg might be involved in the evolvement of these glomerular deposits by influencing lipid metabolism and possibly immune reponses.

Liver X receptors preserve renal glomerular integrity under normoglycaemia and in diabetes in mice

AIMS/HYPOTHESIS

Liver X receptors (LXRs) α and β are nuclear hormone receptors that are widely expressed in the kidney. They promote cholesterol efflux from cells and inhibit inflammatory responses by regulating gene transcription. Here, we hypothesised (1) that LXR deficiency would promote renal decline in a mouse model of diabetes by accelerating intraglomerular cholesterol accumulation and, conversely, (2) that LXR agonism would attenuate renal decline in diabetes.

METHODS

Diabetes was induced with streptozotocin (STZ) and maintained for 14 weeks in Lxrα/β (+/+) (Lxrα, also known as Nr1h3; Lxrβ, also known as Nr1h2) and Lxrα/β (-/-) mice. In addition, STZ-injected DBA/2J mice were treated with vehicle or the LXR agonist N,N-dimethyl-hydroxycholenamide (DMHCA) (80 mg/kg daily) for 10 weeks. To determine the role of cholesterol in diabetic nephropathy (DN), mice were placed on a Western diet after hyperglycaemia developed.

RESULTS

Even in the absence of diabetes, Lxrα/β (-/-) mice exhibited a tenfold increase in the albumin:creatinine ratio and a 40-fold increase in glomerular lipid accumulation compared with Lxrα/β (+/+) mice. When challenged with diabetes, Lxrα/β (-/-) mice showed accelerated mesangial matrix expansion and glomerular lipid accumulation, with upregulation of inflammatory and oxidative stress markers. In the DN-sensitive STZ DBA/2J mouse model, DMHCA treatment significantly decreased albumin and nephrin excretion (by 50% each), glomerular lipids and plasma triacylglycerol (by 70%) and cholesterol (by 48%); it also decreased kidney inflammatory and oxidative stress markers compared with vehicle-treated mice.

CONCLUSIONS/INTERPRETATION

These data support the idea that LXR plays an important role in the normal and diabetic kidney, while showing that LXR, through its inhibitory effect on inflammation and cholesterol accumulation in glomeruli, could also be a novel therapeutic target for DN.

Antiretroviral therapy-induced changes in plasma lipids and the risk of kidney dysfunction in HIV-infected men

In the context of HIV, the initiation of effective antiretroviral therapy (ART) has been found to increase the risk of dyslipidemia in HIV-infected individuals, and dyslipidemia has been found to be a risk factor for kidney disease in the general population. Therefore, we examined changes in lipid profiles in HIV-infected men following ART initiation and the association with future kidney dysfunction. HIV-infected men from the Multicenter AIDS Cohort Study initiating ART between December 31, 1995 and September 30, 2011 with measured lipid and serum creatinine values pre-ART and post-ART were selected. The associations between changes in total cholesterol or high-density lipoprotein following ART initiation and the estimated change in glomerular filtration rate (eGFR) over time were assessed using piecewise linear mixed effects models. There were 365 HIV-infected men who contributed to the analysis. In the adjusted models, at 3 years post-ART, those with changes in total cholesterol >50 mg/dl had an average decrease in eGFR of 2.6 ml/min/1.73 m(2) per year (p<0.001) and at 5 years post-ART, the average decrease was 2.4 ml/min/1.73 m(2) per year (p=0.008). This decline contrasted with the estimates for those with changes in total cholesterol ≤ 50 mg/dl: 1.4 ml/min/1.73 m(2) decrease per year (p<0.001) and 0.1 ml/min/1.73 m(2) decrease per year (p=0.594) for the same time periods, respectively. Large decreases in high-density lipoprotein (a decline of greater than 5 mg/dl) were not associated with declines in eGFR. These results indicate that large ART-related increases in total cholesterol may be a risk factor for kidney function decline in HIV-infected men. Should these results be generalizable to the broader HIV population, monitoring cholesterol changes following the initiation of ART may be important in identifying HIV-infected persons at risk for kidney disease.

Interleukin-1β enhances the intracellular accumulation of cholesterol by up-regulating the expression of low-density lipoprotein receptor and 3-hydroxy-3-methylglutaryl coenzyme A reductase in podocytes

The aim of this article is to investigate whether interleukin-1β (IL-1β) could regulate the intracellular accumulation of cholesterol and the expression of lipid-metabolism-related regulators in podocytes in vitro and the potential mechanisms. Podocytes were treated with 200 μg/ml of low-density protein (LDL), 20 ng/ml of IL-1β, or 200 μg/ml of LDL plus 5-20 ng/ml of IL-1β for 24 h in vitro. The contents of intracellular cholesterol were determined by enzymatic assays and Oil Red O staining. The levels of LDL receptor (LDLr), 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, sterol regulatory element binding protein 2 (SREBP-2), SREBP cleavage activating protein (SCAP), and insulin-induced gene-1 (Insig-1) expression were characterized by real-time polymerase chain reaction (RT-PCR) and Western blot assays. Treatment with IL-1β or LDL alone increased the contents of intracellular cholesterol (P < 0.05 for both) and lipid droplets, and treatment with both IL-1β and LDL further increased the accumulation of intracellular cholesterol in podocytes (P < 0.05 vs. LDL alone). While loading with LDL significantly inhibited the expression of LDLr, HMG-CoA reductase, nuclear SREBP-2 (nSREBP-2), SCAP, and Insig-1 by 40-62% treatment with IL-1β enhanced the expression of LDLr, HMG-CoA reductase and nSREBP-2, but not Insig-1, in podocytes (P < 0.05 vs. control). Treatment with both LDL and IL-1β significantly increased the levels of LDLr and HMG-CoA reductase expression and the ratio of SCAP to Insig-1, as compared with that in the LDL-treated podocytes (P < 0.05 vs. LDL alone). Our data indicated that IL-1β mitigated the LDL-triggered SCAP-SREBP-2-mediated feedback inhibition on the expression of LDLr and HMG-CoA reductase, leading to the intracellular accumulation of LDL-cholesterol in podocytes in vitro.

Citrus bergamia Risso & Poiteau juice protects against renal injury of diet-induced hypercholesterolemia in rats

The present study was designed to evaluate the protective effect of treatment with Citrus bergamia juice (1 mL/day, for 30 days) against hypercholesterolemic diet-induced renal injury in rat.C. bergamia juice provoked a significant reduction in the plasma levels of cholesterol, triglycerides and LDL, and an increase in HDL levels, versus hyperlipidemic controls (p < 0.05). Plasma creatinine levels, measured to assess renal glomerular function, did not change compared with hyperlipidemic controls (0.37 +/- 0.11 mg/dL and 0.32 +/- 0.10 mg/dL, respectively). Moreover, in vivo lipid peroxidation was measured in kidney homogenate; C. bergamia juice administration significantly decreased MDA levels elevations compared with hyperlipidemic controls (4.10 +/- 0.10 nmol/mg protein and 4.78 +/- 0.15 nmol/mg protein, respectively).Histological observations of the kidney supported the biochemical data and indicated a protective effect of C. bergamia juice on the development of renal damage in hypercholesterolemic rats.The antioxidant potential of C. bergamia juice was examined in two in vitro systems: in the DPPH test the juice showed a noticeable effect on scavenging free radicals (IC(50) = 25.01 +/- 0.70 +/-L); in the reducing power assay it showed a strong activity, too (1.44 +/- 0.01 ASE/mL).These findings suggest that C. bergamia juice has a protective role in hypercholesterolemic diet-induced renal damage, which may be attributed to its antioxidant properties.

Disorders of lipid metabolism and chronic kidney disease in the elderly

The growing population of elderly with chronic kidney disease (CKD) is at greater risk for cardiovascular disease given an independent risk of CKD, as well as from added dyslipidemia of aging and renal dysfunction. Changes in lipid metabolism with more isodense and high-dense, triglyceride-rich particles, low high-density lipoprotein cholesterol, and increased triglyceride levels occur with CKD and aging, which are noted to have significant atherogenic potential. In addition, lipid abnormalities may lead to the progression of CKD. Cardiovascular mortality in the end-stage renal disease population is more than 10 times higher than the general population. Treatment of dyslipidemia in the general population suggests important benefits both in reducing cardiovascular risk and in the prevention of cardiovascular disease. Secondary analyses of elderly subgroups of various large prospective studies with statins suggest treatment benefit with statin use in the elderly. Similarly limited data from secondary analyses of CKD subgroups of larger prospective trials using statins also suggest a possible benefit in cardiovascular outcomes and the progression of kidney disease. However, randomized trials have yet to confirm similar benefits and targets of treatment for dyslipidemia in the elderly with CKD and end-stage renal disease. Treatment in the elderly with CKD should be individualized and outweigh risks of side effects and drug-drug interactions. There is a need for further specific investigation of dyslipidemia of CKD in the aging population in relation to renal disease progression and cardiovascular outcome.

Dyslipidemia in chronic kidney disease: managing a high-risk combination

Cardiovascular disease (CVD) is the single largest cause of mortality in patients with chronic kidney disease (CKD), with those patients having a 10-year CVD-related morbidity and mortality of > 20%. This has led to the inclusion of CKD as a CVD equivalent, and justifies the aggressive treatment of modifiable risk factors such as dyslipidemia. Primary care physicians (PCP) often manage patients with CKD in the early stages of the disease and have a pivotal role in affecting long-term outcomes in CKD patients related to cardiovascular and all-cause mortality. Therefore, treatment of dyslipidemia often becomes the responsibility of the PCP and comes with its own set of challenges because of CKD-related issues (eg, the dose adjustments required). Exacerbating this problem is the fact that current guidelines are lengthy and complex. This article discusses the current guidelines for treating dyslipidemia in patients with CKD. Few studies have examined the safety and efficacy of pharmacotherapy for treatment of dyslipidemia in the CKD population, and ongoing studies such as the Study of Heart and Renal Protection (SHARP) should help clarify the current treatment guidelines.

Mechanisms of tissue injury in renal artery stenosis: ischemia and beyond

Renal injury distal to an atherosclerotic renovascular obstruction reflects multiple intrinsic factors producing parenchymal tissue injury. Atherosclerotic disease pathways superimposed on renal arterial obstruction may aggravate damage to the kidney and other target organs, and some of the factors activated by renal artery stenosis may in turn accelerate the progression of atherosclerosis. This cross-talk is mediated through amplified activation of renin-angiotensin system, oxidative stress, inflammation, and fibrosis-pathways notoriously involved in renal disease progression. Oxidation of lipids also accelerates the development of fibrosis in the stenotic kidney by amplifying profibrotic mechanisms and disrupting tissue remodeling. The extent to which actual ischemia modulates injury in the stenotic kidney has been controversial, partly because the decrease in renal oxygen consumption usually parallels a decrease in renal blood flow, and because renal vein oxygen pressure in the affected kidney is not decreased. However, recent data using novel methodologies demonstrate that intra-renal oxygenation is heterogeneously affected in different regions of the kidney. Activation of such local injury within the kidney may lead to renal dysfunction and structural injury, and ultimately unfavorable and irreversible renal outcomes. Identification of specific pathways producing progressive renal injury may enable development of targeted interventions to block these pathways and preserve the stenotic kidney.

Dyslipidemia of kidney disease

PURPOSE OF REVIEW

Chronic kidney disease is associated with specific alterations of lipoprotein metabolism that may be linked to accelerated atherosclerosis and cardiovascular disease. This review summarizes current knowledge of the pathophysiology of renal dyslipidemia and the therapeutic options.

RECENT FINDINGS

The renal dyslipidemia is characterized by accumulation of intact and partially metabolized triglyceride-rich apoB-containing and apoC-containing lipoproteins. Increased concentrations of atherogenic apoC-III rich lipoproteins, the hallmark of renal dyslipidemia, may result from disturbances of insulin metabolism and action in chronic kidney disease. Novel findings strongly suggest that apoC-III triggers a cascade of pro-inflammatory events, which ultimately can result in endothelial dysfunction and vascular damage. Disappointingly, recently reported intervention trials with statins have failed to show any benefit on cardiovascular disease in patients with advanced renal failure.

SUMMARY

During recent years, our understanding of the character and biological significance of the dyslipidemia of chronic kidney disease, and its link to cardiovascular disease, has increased. However, our knowledge about its proper management is still very limited.

Association of candidate gene polymorphisms with chronic kidney disease in Japanese individuals with hypertension

Although hypertension has been recognized as a risk factor for chronic kidney disease (CKD), the genetic factors for predisposition to CKD in individuals with hypertension remain largely unknown. The purpose of this study was to identify the genetic variants that confer susceptibility to CKD among individuals with hypertension. The study population comprised 3696 Japanese individuals with hypertension (2265 men, 1431 women), including 1257 individuals (789 men, 468 women) with CKD (estimated glomerular filtration rate (eGFR) <60 ml min(-1) per 1.73 m(2)) and 2439 controls (1476 men, 963 women; eGFR >or=60 ml min(-1) per 1.73 m(2)). The genotypes for 30 polymorphisms of 26 candidate genes were determined. An initial screening of allele frequencies by the chi(2)-test revealed that eight polymorphisms were significantly (false discovery rate <0.05) associated with the prevalence of CKD in hypertensive individuals. Subsequent multivariable logistic regression analysis with adjustment for covariates as well as a stepwise forward selection procedure revealed that the T --> C (Val591Ala) polymorphism of APOB (rs679899), the -681C --> G polymorphism of PPARG (rs10865710), the T --> C (Cys1367Arg) polymorphism of WRN (rs1346044), the -850C --> T polymorphism of TNF (rs1799724), the -219G --> T polymorphism of APOE (rs405509), the C --> T polymorphism of PTGS1 (rs883484) and the 41A --> G (Glu14Gly) polymorphism of ACAT2 (rs9658625) were significantly (P<0.05) associated with the prevalence of CKD. Our results suggest that APOB, WRN, ACAT2, APOE, PPARG, TNF and PTGS1 are susceptibility loci for CKD among Japanese individuals with hypertension. Determination of the genotypes for these polymorphisms may prove informative for the assessment of genetic risk for CKD among such individuals.

Impact of Kidney Disease and Blood Pressure on the Development of Cardiovascular Disease

Background— Kidney disease is associated with an increased risk of cardiovascular disease (CVD); however, there have been few well-designed prospective studies of this issue in Asian populations. Recent epidemiological studies have suggested that a lower blood pressure level may be associated with an increased risk of CVD in individuals with kidney dysfunction.

Methods and Results— Using data from 10 community-based cohort studies in Japan, we conducted follow-up on a total of 30 657 individuals 40 to 89 years of age without preexisting CVD or kidney failure and examined the relationship between reduced glomerular filtration rate (GFR) and the risk of CVD. During an average 7.4-year follow-up, 727 individuals experienced CVD. The age- and sex-adjusted incidence of CVD increased significantly in subjects with GFR of 60 to 89 mL · min −1 · 1.73 m −2 (4.3 per 1000 person-years, P =0.002) and in those with a GFR <60 mL · min −1 · 1.73 m −2 (6.5, P <0.001) compared with those with a GFR ≥90 mL · min −1 · 1.73 m −2 (2.9). Even after adjustment for potential confounding factors, subjects with a GFR <60 mL · min −1 · 1.73 m −2 had a 57% (95% CI 14% to 115%) greater risk of CVD than those with a GFR ≥90 mL · min −1 · 1.73 m −2 . The multivariate-adjusted hazard ratios of CVD increased in a log-linear manner with elevations in blood pressure levels, regardless of GFR levels (all P for trend <0.01).

Conclusions— Our findings suggest that a reduced GFR is a significant risk factor for CVD in the general Japanese population. Additionally, a log-linear association of blood pressure level with CVD risk was observed, without evidence of a J-curve association, regardless of GFR levels.

Association of a polymorphism of the apolipoprotein E gene with chronic kidney disease in Japanese individuals with metabolic syndrome

The purpose of the present study was to identify genetic variants that confer susceptibility to chronic kidney disease (CKD) in Japanese individuals with metabolic syndrome. The study population comprised 2150 Japanese individuals with metabolic syndrome, including 411 subjects with CKD [estimated glomerular filtration rate (eGFR) <50 mL/min/1.73m(2)] and 1739 controls (eGFR >/=60 mL/min/1.73m(2)). The genotypes for 100 polymorphisms of 80 candidate genes were determined. The chi-square test, multivariable logistic regression analysis with adjustment for covariates, as well as a stepwise forward selection procedure revealed that nine polymorphisms of APOE, ABCA1, PTGS1, TNF, CPB2, AGTR1, OR13G1, and GNB3 were associated (P<0.05) with the prevalence of CKD. Among these polymorphisms, the -219G-->T polymorphism of APOE (rs405509) was most significantly associated with CKD in Japanese individuals with metabolic syndrome.

Low density lipoproteins transactivate EGF receptor: role in mesangial cell proliferation

Hyperlipidemia and the glomerular accumulation of atherogenic lipoproteins (low density lipoprotein, LDL; and its oxidatively-modified variants, ox-LDL) are commonly associated with the development of glomerular mesangial proliferative diseases. However, cellular signaling mechanisms by which atherogenic lipoproteins stimulate mesangial cell proliferation are poorly defined. In this study, we examined the effect of atherogenic lipoproteins on the activation of mesangial cell epidermal growth factor (EGF) receptor, mitogen activated protein kinase (MAP kinase), Ras, and mesangial cell proliferation. Stimulation of mesangial cells with LDL, and with greater activity, ox-LDL, markedly induced the transactivation of EGF receptor within 5 min of stimulation; the effect persisted up to at least 60 min LDL, and with a greater degree, ox-LDL, increased the activation of Ras, MAP kinase, and mesangial cell proliferation. Inhibition of EGF receptor kinase activity and/or MAP kinase activation blocked both LDL- and ox-LDL-induced mesangial cell proliferation. We suggest that the accumulation of LDL and more potently its oxidized forms within the glomerulus, through the transactivation of EGF receptor, stimulate down-stream Ras-MAP kinase signaling cascade leading to mesangial cell proliferation. Regulation of glomerular accumulation of atherogenic lipoproteins and/or EGF receptor signaling may provide protective environment against mesangial hypercellularity seen in glomerular diseases.

Positive association between plasma homocysteine level and chronic kidney disease

BACKGROUND

Increasing experimental evidence, including recently developed animal models, supports a role for homocysteine in the development of chronic kidney disease (CKD). However, relatively few clinical/epidemiological studies have examined this hypothesis in humans. We examined the relationship between plasma homocysteine level and CKD in a population-based study of older Australians.

METHODS

Community-based study (1992-1994) among 2,609 individuals (58.6% women), aged 49-98 years, free of clinical cardiovascular disease in the Blue Mountains region, west of Sydney, Australia. The main outcome-of-interest was CKD (n = 461), defined as estimated glomerular filtration rate of <60 ml/min/1.73 m(2).

RESULTS

Higher plasma homocysteine levels were positively associated with CKD, independent of smoking, body mass index, diabetes mellitus, hypertension, cholesterol levels, and other confounders. The multivariable odds ratio (OR; 95% confidence intervals, CI) comparing quartile 4 of plasma homocysteine (>14 micromol/l) to quartile 1 (< or =9 micromol/l) was 10.44 (6.99-15.60), p-trend <0.0001. This association persisted in both men and women separately. The results were also consistent in subgroup analyses by categories of diabetes mellitus and hypertension.

CONCLUSIONS

Higher plasma homocysteine levels are associated with CKD in a community-based sample of older Australians. This association appeared to be independent of diabetes mellitus and hypertension.

Hyperlipidemia is associated with accelerated chronic kidney disease progression after lung transplantation

Hyperlipidemia is associated with faster progression of chronic kidney disease (CKD) in the general public. We sought to investigate this association after lung transplantation. Data was retrospectively collected on 230 lung recipients transplanted between January 1997 and December 2003. Estimated glomerular filtration rates (eGFR) and lipid levels were recorded at regular intervals posttransplant. Independent associations between lipid levels early posttransplant and pertinent renal endpoints were investigated. Baseline LDL was 110 +/- 35 mg/dL and remained unchanged at 6 months. A faster decline in eGFR was seen in those with 6 month LDLs > versus < the mean level of 110 mg/dL (p = 0.05). By 6 months posttransplant eGFRs were lower in the 6 month LDL > versus < 110 mg/dL group (53 +/- 23 vs. 62 +/- 29 mL/min/1.73 m2, p = 0.01), a difference that persisted at 60 months (39 +/- 24 vs. 73 +/- 57 mL/min/1.73 m2, p = 0.05). On univariate analysis, a 6 month LDL in the highest quartile, i.e. >140 mg/dL, predicted faster progression to CKD, defined as declining to an eGFR < 30 mL/min/1.73 m2 (HR 1.5, p = 0.01). This finding persisted in the multivariate Cox-proportional model (HR 1.4, p = 0.02). Hyperlipidemia predicts faster decline in renal function after lung transplant. Prospective trials are needed to confirm this finding.

Lysophosphatidylcholine stimulates EGF receptor activation and mesangial cell proliferation: regulatory role of Src and PKC

Lysophosphatidylcholine (LPC), a major component of oxidized-low density lipoproteins (ox-LDL), modulates various pathobiological processes involved in vascular and glomerular diseases. Although several studies have shown increased plasma concentrations of ox-LDL as well as LPC in patients with renal disease, the role of LPC in mesangial cell proliferation and associated signaling mechanisms are not clearly understood. In this study, we have shown that LPC induced the phosphorylation of epidermal growth factor receptor (EGFR), as well as the p42/44 MAP kinases. LPC activated Src-kinase and protein kinase C (PKC), and both Src kinase inhibitor PP-2 and PKC inhibitor inhibited the activation of EGFR by LPC. LPC (5-25 microM) stimulated human mesangial cell proliferation by 4-5 fold. Preincubation of mesangial cells with the Src inhibitor (PP-2), or PKC inhibitor (bisindolylmaleimide GF109203-X), or EGF receptor kinase inhibitor (AG1478), or MEK inhibitor (PD98059) significantly inhibited LPC-mediated mesangial cell proliferation. The data suggest that LPC, by activating Src and PKC signaling pathways, stimulates EGF receptor transactivation and down-stream MAP kinase signaling resulting in mesangial hypercellularity, which is a characteristic feature of diverse renal diseases.

Association of cigarette smoking with albuminuria in the United States: the third National Health and Nutrition Examination Survey

BACKGROUND

The association of cigarette smoking with albuminuria has been reported but not examined in a representative U.S. population. No study has evaluated the association between serum cotinine (a biological marker for tobacco exposure) and kidney damage.

METHODS

A cross-sectional analysis was conducted among 15,719 adult participants of the third National Health and Nutrition Examination Survey to assess the association between smoking exposure and kidney damage. Smoking was assessed by self-reported lifetime cigarette use and serum cotinine. Kidney damage was assessed by urine albumin-to-creatinine ratio (ACR), with albuminuria defined as ACR of > or =17 microg/mg in males and > or =25 microg/mg in females.

RESULTS

The analysis included 13,121 with normal albumin (mean ACR 6.3 microg/mg) and 2,414 with albuminuria (mean ACR 143 microg/mg); hypertension was prevalent in 27% and 59%, respectively. Former smoking was similar between groups (21%), while current smoking was more common in persons with albuminuria (26%) compared to normal ACR (21%). Adjusted for other risk factors, among hypertensives, current smokers were 1.85 (95% CI: 1.29, 2.64) times more likely to have albuminuria than never smokers. Current smokers with a > or =40 pack-year history were at highest risk for albuminuria. Among non-smoking hypertensives, those exposed to passive smoke (highest versus lowest quartile of serum cotinine) were 1.41 (95% CI: 1.04, 1.90) times more likely to have albuminuria. Former smoking with cessation of > or =1 year among hypertensives was not associated with albuminuria. Among non-hypertensives, smoking and albuminuria were not consistently associated.

CONCLUSION

Current and passive smoking, but not former smoking, were associated with the presence of albuminuria in the general U.S. population with hypertension, indicating a benefit to the kidney from smoking cessation.

Apo E gene polymorphism on development of diabetic nephropathy

Type 2 diabetes causes premature morbidity and mortality due to the complications of atherosclerosis and diabetic nephropathy (DN). Polymorphism of Apo E gene is known to influence lipid metabolism. Apo E is polymorphic, consisting of three common isoforms (epsilon2, epsilon3 and epsilon4) encoded by three alleles (2, 3 and 4) in exon 4 on chromosome 19. The aim of this study was to investigate the effect of Apo E polymorphism as a prognostic risk factor for the development of DN. A total of 108 NIDDM patients were recruited from the Nephrology and Endocrinology Departments of our hospital. All subjects were divided into three groups: Group I: diabetes with nephropathy (n:37), group II: diabetes without nephropathy (n:71), group III: controls (n:46). Apo E genotypes were determined by real-time PCR. The epsilon4 allele frequency was significantly higher in-group I (10.8%) than in-group III (2.2%), (p < 0.05). In diabetics without nephropathy, the total cholesterol and LDL cholesterol levels were significantly lower in subjects with epsilon2 alleles than epsilon3 and epsilon4 alleles. In conclusion, the present prospective study indicates that the epsilon4 allele of the Apo E polymorphism is one of the prognostic risk factors involved in the development of DN with type 2 diabetes mellitus.

Group IVA phospholipase A2-mediated production of fibronectin by oxidized LDL in mesangial cells

The deposition of atherogenic lipoproteins such as oxidized low-density lipoprotein (oxLDL) within the mesangium is involved in the overproduction of extracellular matrix proteins, a key event in the progression of glomerular diseases including glomerulosclerosis. To clarify the mechanisms underlying the oxLDL-induced production of extracellular matrix proteins, we examined the possible involvement of group IVA phospholipase A(2) (PLA(2)) using human mesangial cells and group IVA PLA(2)-deficient mouse mesangial cells. oxLDL accelerated the production of fibronectin and collagen (type IV), components of extracellular matrix proteins, with the preceding release of arachidonic acid. Methyl arachidonyl fluorophosphonate (MAFP), known as an inhibitor of group IVA PLA(2), markedly suppressed the oxLDL-induced production of fibronectin as well as the release of arachidonic acid, whereas it did not inhibit the production of collagen. The inhibitory effect of MAFP on the production of fibronectin was reversed by adding arachidonic acid and 12-hydroxyeicosatetraenoic acid. Furthermore, we found that in group IVA PLA(2)-deficient mouse mesangial cells, the production of fibronectin in response to oxLDL was weak as compared with that in wild-type cells. However, the production by oxLDL of collagen was not suppressed in the group IVA PLA(2)-deficient cells. These findings suggest that group IVA PLA(2) is involved in the production of fibronectin in oxLDL-stimulated mesangial cells.

Platelet-activating factor (PAF) increase intracellular lipid accumulation by increasing both LDL and scavenger receptors in human mesangial cells

Intra- and extracellular lipid accumulation and the production of inflammatory mediators by renal and accessory cells may play an important role in the initiation and progression of these lesions. Platelet activating factor (PAF) is a biologically active phospholipid that is produced by various cells upon activation by different stimuli. It has been suggested that PAF plays a role in atherogenesis, and several studies indicated its participation in the pathogenesis of renal diseases. The aim of this study is to investigate the role of PAF on intracellular lipid accumulation and gene regulation of lipoprotein receptors in human mesangial cells (HMCs). A human mesangial cell line (HMC) was used to study the effects of PAF on foam cell formation by Oil red O staining and on the expression of LDLr, SR-AI, and PAF-R mRNA using RT-PCR. Native LDL caused foam cell formation in HMC in the presence of PAF. PAF enhanced LDLr expression and overrode LDL receptor suppression induced by a high concentration of LDL. Moreover, it enhanced SR-AI expression. PAF also caused increase in PAF-R expression. The above data suggest that PAF enhances its own receptor expression and then increases lipid accumulation by dysregulating LDL receptor regulation and inducing scavenger receptor expression in HMCs. These results suggest that PAF has a potential role in lipid mediated renal injury.

Activation of Nrf2/ARE pathway protects endothelial cells from oxidant injury and inhibits inflammatory gene expression

The antioxidant response element (ARE) is a transcriptional control element that mediates expression of a set of antioxidant proteins. NF-E2-related factor 2 (Nrf2) is a transcription factor that activates ARE-containing genes. In endothelial cells, the ARE-mediated genes are upregulated by atheroprotective laminar flow through a Nrf2-dependent mechanism. We tested the hypothesis that activation of ARE-regulated genes via adenovirus-mediated expression of Nrf2 may suppress redox-sensitive inflammatory gene expression. Expression of Nrf2 in human aortic endothelial cells (HAECs) resulted in a marked increase in ARE-driven transcriptional activity and protected HAECs from H2O2-mediated cytotoxicity. Nrf2 suppressed TNF-α-induced monocyte chemoattractant protein (MCP)-1 and VCAM-1 mRNA and protein expression in a dose-dependent manner and inhibited TNF-α-induced monocytic U937 cell adhesion to HAECs. Nrf2 also inhibited IL-1β-induced MCP-1 gene expression in human mesangial cells. Expression of Nrf2 inhibited TNF-α-induced activation of p38 MAP kinase. Furthermore, expression of a constitutively active form of MKK6 (an upstream kinase for p38 MAP kinase) partially reversed Nrf2-mediated inhibition of VCAM-1 expression, suggesting that p38 MAP kinase, at least in part, mediates Nrf2's anti-inflammatory action. In contrast, Nrf2 did not inhibit TNF-α-induced NF-κB activation. These data identify the Nrf2/ARE pathway as an endogenous atheroprotective system for antioxidant protection and suppression of redox-sensitive inflammatory genes, suggesting that targeting the Nrf2/ARE pathway may represent a novel therapeutic approach for the treatment of inflammatory diseases such as atherosclerosis.

Paraoxonase 1 192 and 55 polymorphisms in nephrotic children

Human paraoxonase 1 (PON1) is a serum enzyme related to high-density lipoprotein which has a major role in preventing oxidative modification of low-density lipoprotein. Due to its amino acid substitution PON1 has two genetic polymorphisms. These polymorphisms are characterized by the location of glutamine (A genotype) and arginine (B genotype) at position 192, and leucine (L genotype) and methionine (M genotype) at position 55. Hyperlipidemia and increased lipid oxidation in nephrotic syndrome may lead to glomerulosclerosis and progression of the glomerular disease. In this study we aimed to investigate PON1 192 and PON1 55 polymorphisms in children with focal segmental glomerulosclerosis (FSGS) and control subjects. The study included 25 children with biopsy-proven FSGS and 30 healthy controls. We demonstrated a statistically significant difference between FSGS patients and control subjects with respect to the distribution of the PON1 polymorphism. The AA genotype was less frequent and the AB+BB genotype was more frequent in FSGS patients than in controls (48 versus 73% for AA genotype and 52 versus 27% for AB+BB genotype, p<0.05). Distributions of PON1 55 genotypes of FSGS and control subjects were also statistically different (76 versus 43% for LL genotype and 24 versus 57% for LM+MM genotype, p<0.05) (case-control study, dominant model, Fisher's exact test). The distributions of both genotypes in subgroups of FSGS (stable renal function versus declining renal function) were not statistically different. We conclude in this preliminary study that presence of B allele and/or L allele may be risk factors for the development of FSGS in children.

Dyslipidemia and the progression of renal disease in chronic renal failure patients

Dyslipidemia is a common complication of progressive kidney disease and contributes to the high cardiovascular morbidity and mortality of chronic kidney disease (CKD) patients. Recent evidence also suggests a role for dyslipidemia in the development and progression of renal disease. Experimental studies have demonstrated that lipids may induce glomerular and tubulointerstitial injury, and that lipid-lowering treatments ameliorate renal injury. Various lipid abnormalities have been associated with the development and progression of renal disease in diabetic and nondiabetic patients. Population-based studies and studies of diabetic patients have reported associations of various lipid abnormalities with the development of renal disease. In patients with CKD, lipid abnormalities have also been associated with renal disease progression. Post hoc analyses of some large clinical trials on patients with vascular disease, diabetes, or dyslipidemia, and a meta-analysis of small, prospective, controlled studies on patients with CKD (diabetics and nondiabetics) suggest that statins may slow the progression of kidney disease. It is unclear whether the beneficial renal effects of statins are due to the reduction of serum cholesterol levels and/or their pleiotropic effects. There is also evidence for synergistic renoprotective effects between statins and renin-angiotensin system inhibitors. According to the results of post hoc analysis of several studies, treatment with fibrates does not seem to confer renoprotection, but evidence is scarce. In summary, there is growing evidence that lipid abnormalities may be a risk factor for renal disease, and that statins appear to confer a renoprotective effect.

Biomarkers of inflammation and progression of chronic kidney disease

BACKGROUND

Chronic kidney disease is associated with higher levels of inflammatory biomarkers. Statins have anti-inflammatory properties and may attenuate loss of kidney function. Although inflammation may mediate progressive renal injury, the relation between statin use, markers of inflammation, and the rate of kidney function loss has not been elucidated. We examined the association between pravastatin use, levels of C-reactive protein (CRP), soluble tumor necrosis factor receptor II (sTNFrii), and the rate of kidney function loss.

METHODS

We performed a post hoc analysis of data from a randomized placebo controlled trial of pravastatin 40 mg daily in people with previous myocardial infarction. Glomerular filtration rate (GFR) was estimated using the Modification of Diet in Renal Disease Study (MDRD) GFR equation. We studied 687 subjects with chronic kidney disease (GFR < 60 mL/min/1.73 m(2)) who did not experience a cardiovascular event during follow-up. Multivariate linear regression was used to study the relation between baseline CRP and sTNFrii and the rate of kidney function loss in mL/min/1.73 m(2)/year. Cross-product interaction terms were used to determine if these relations varied with pravastatin use.

RESULTS

Median baseline GFR was 54.5 mL/min/1.73 m(2) (interquartile range 49.7, 57.8) and median duration of follow-up was 58 months. Higher baseline CRP level was independently associated with more rapid kidney function loss (highest tertile 0.6 mL/min/1.73 m(2) per year faster than lowest tertile) (P= 0.001). A similar independent relation was observed between tertile of sTNFrii and rate of kidney function loss (highest tertile 0.5 mL/min/1.73 m(2) per year faster than lowest tertile) (P= 0.006). Subjects with both CRP and sTNFrii in the highest tertile ("inflamed" status) appeared to derive more renal benefit from pravastatin than those without (P for interaction 0.047). In these 108 subjects, renal function loss in pravastatin recipients was 0.8 mL/min/1.73 m(2)/year slower than placebo (95% CI 0 to 1.5 mL/min/1.73 m(2)/year slower) (P= 0.039).

CONCLUSION

Higher CRP and sTNFrii are independently associated with faster rates of kidney function loss in chronic kidney disease. Pravastatin appears to prevent loss of kidney function to a greater extent in individuals with greater evidence of inflammation, although this was of borderline significance. These data suggest that inflammation may mediate the loss of kidney function among subjects with chronic kidney disease and concomitant coronary disease.

Chronic kidney disease and cardiovascular disease in a general Japanese population: the Hisayama Study

BACKGROUND

Chronic kidney disease has been shown to be an independent risk factor for cardiovascular disease in high-risk populations. However, this relationship is inconclusive in community-based populations.

METHODS

To clarify this issue, we followed 2634 community-dwelling individuals without cardiovascular disease, aged 40 years or older, for 12 years and examined the relationship between chronic kidney disease and the incidence of cardiovascular disease.

RESULTS

During the follow-up period, 99 subjects (56 men and 43 women) experienced coronary heart disease, 137 subjects (60 men and 77 women) ischemic stroke, and 60 subjects (26 men and 34 women) hemorrhagic stroke. In men, the age-adjusted incidence of coronary heart disease was significantly higher in subjects with chronic kidney disease than in those without it (6.2 vs. 2.9 per 1000 person-years) (P < 0.05), but such a relationship was not observed with ischemic stroke. In contrast, in women, the age-adjusted incidence of ischemic stroke was significantly higher in subjects with chronic kidney disease than in those without it (3.4 vs. 2.5) (P < 0.05), while that of coronary heart disease was not. Chronic kidney disease was not found to be associated with the incidence of hemorrhagic stroke. In multivariate analysis, even after adjustments for traditional and nontraditional cardiovascular disease risk factors, chronic kidney disease was found to be an independent risk factor for the occurrence of coronary heart disease in men [hazard ratio (HR), 2.26; 95% CI, 1.06-4.79], and for the occurrence of ischemic stroke in women (HR, 1.91; 95% CI, 1.15-3.15).

CONCLUSION

Our findings suggest that chronic kidney disease is an independent risk factor for the occurrence of cardiovascular disease in the general Japanese population.

Fluvastatin in the treatment of dyslipidemia associated with chronic kidney failure and renal transplantation

Premature atherosclerotic coronary heart disease driven by multiple risk factors is a major cause of morbidity and mortality among the 6 million patients in the United States with chronic renal failure. Consensus is that kidney failure and renal transplantation patients should be treated aggressively for dyslipidemia. Major medical literature databases were searched for published information about fluvastatin, a HMG-CoA reductase inhibitor, used in patients with impaired renal function. This article characterizes the dyslipidemia observed in these clinical settings and reviews the clinical experience with fluvastatin.

Paraoxonase, total antioxidant response, and peroxide levels in children with steroid-sensitive nephrotic syndrome

Reactive oxygen species (ROS) are reported to play a role in inducing the proteinuria of nephrotic syndrome (NS). This study investigated paraoxonase (PON), total antioxidant response (TAR), and oxidant total peroxide together with serum proteins and lipoproteins in children with steroid-sensitive NS. The study included 40 children with steroid-sensitive NS (21 with acute-period NS in group I, 19 nonproteinuric while receiving steroids in group II) and 22 sex- and age-matched formerly nephrotic children in remission weaned from steroids (group III). The following parameters were determined: total peroxide, oxidative stress index (OSI), PON and TAR. Serum proteins and lipoproteins were also determined. Patients in the active phase of NS had significantly lower PON and TAR levels and higher OSI and total peroxide values than those in full remission; no differences were found in PON, TAR, or OSI values of groups I and II. Significant correlations were found between PON, TAR, and total peroxide. Serum total protein had a significantly positive correlation with PON and negative correlation with total peroxide in acute-period NS patients. Our results demonstrate greater oxidative stress and decreased antioxidants in the active phase of steroid-sensitive NS and while patients receive steroids than during full remission. Low-dose alternate-day steroids do not seem to decrease oxidative stress even while proteinuria ceases. Despite some conflicting data increased oxidation and/or decreased antioxidant response may be related to the pathogenesis of steroid-sensitive NS.

IGF-1 induces rat glomerular mesangial cells to accumulate triglyceride

Rat glomerular mesangial cells (MC) become lipid-laden foam cells when they are exposed to IGF-1. IGF-1 increased accumulation of triglyceride (TG) 2.5-fold in MC after 7 days. TG accumulation resulted from enhanced macropinocytosis and decreased efflux secondary to a 40-50% reduction in peroxisome proliferator-activated receptor (PPAR)-delta (PPARdelta). There was no evidence of primary or secondary changes in cholesterol or TG synthesis, increased uptake by LDL or scavenger receptors, or reduced efflux via ATP-binding cassette A-1. Although the lipid moiety taken up can be influenced by the concentration of cholesterol or TG in the medium, in standard medium MC preferentially accumulate TG. TG-rich MC foam cells fail to contract in response to angiotensin II (Berfield AK, Andress DL, and Abrass CK. Kidney Int 62: 1229-1237, 2002); however, their migratory response to IGF binding protein-5 is unaffected. This differs from cholesterol loading, which impairs both phagocytosis and migration. These findings have important implications for understanding the mechanisms that contribute to lipid accumulation in MC and the functional consequences of different forms of foam cells. These observations are relevant to understanding vascular disease and progressive renal diseases that are accelerated by abnormalities in lipid metabolism.

Beneficial cardio-renovascular effects of a low-molecular-weight heparin-derivative on adriamycin-induced glycosaminoglycanuria and tissue lipid abnormalities

The present work includes a study on the glycosaminoglycanuric condition induced by adriamycin (ADR, a chemotherapeutic agent) and the accompanying secondary hyperlipidemia, wherein the treatment with a low-molecular-weight heparin-derivative (LMWH), certoparin, is evaluated for its protective role (if any) on these parameters. Two groups of male albino rats of the Wistar strain (140+/-10 g) received a single intravenous injection of adriamycin (7.5 mg/kg), and one of these groups was treated with a low-molecular-weight heparin-derivative (Certoparin Sodium, Troparin; 300 microg/day/rat s.c.), commencing on day 8, for a week. Urinary total glycosaminoglycans excretion of the untreated ADR-induced group was found to increase on the 8th and the 15th days of observation, when compared with the controls. The LMWH treatment commencing on day 8 resulted in minimising the glycosaminoglycans (GAGs) excretion by day 15 (p<0.001). Plasma, cardiac, hepatic and renal lipids (cholesterol, triglycerides and phospholipids) showed a sharp increase in the pathologic group, along with a rise in plasma LDL and VLDL cholesterol and drop in HDL cholesterol levels, paralleled by abnormal activities of the enzymes involved in lipid metabolism. LMWH treated group showed a normalised lipid profile and the activities of the lipid-metabolising enzymes was close to that of controls. It is concluded herein that adriamycin administration resulted in severe nephropathy manifested by increased glycosaminoglycanuria and abnormal lipid metabolism, and that LMWH treatment afforded substantial protection by restoring glomerular structure and function, and normalised the plasma and tissue lipid levels, lipoprotein profile and the activities of lipid-metabolising enzymes.