Kidney disease and cardiovascular disease: implications of dyslipidemia

HDL and Kidney Diseases

Serum lipid profiles, as well as HDL can be altered in patients with kidney diseases. There are various types of kidney diseases, including nephrotic syndrome and chronic kidney disease. In patients with nephrotic syndrome, plasma levels of HDL cholesterol and ApoA-I were within or below the normal limits. The HDL cholesterol: total cholesterol ratio decreased compared to healthy individuals. In patients with chronic kidney disease (CKD), reverse cholesterol transport function of HDL is impaired, and CKD also affects the composition and function of HDL. Cardiovascular disease (CVD) is the severe complication of CKD. Furthermore, HDL might also be a potential target for the prevention of cardiovascular complications associated with CKD.

Paraoxonase 1 (PON1) L55M and Q192R polymorphisms are not associated with chronic kidney disease in Thai individuals with type 2 diabetes

BACKGROUND

Decreased paraoxonase 1 (PON1) activity and PON1 polymorphisms have been found to be associated with chronic kidney disease (CKD) in type 2 diabetes mellitus (T2DM).

OBJECTIVE

This study aimed to investigate the association of the PON1 L55M and Q192R polymorphisms with CKD in T2DM, as well as their relationship with PON1 activity.

METHODS

A total of 166 T2DM patients, including 83 CKD patients and 83 non-CKD patients, were recruited. Biochemical parameters and paraoxonase (PONase) and arylesterase (AREase) activities were measured. The PON1 L55M and Q192R polymorphisms were analysed by a polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) method. Data were analysed using the chi-square test, Student's t-test and logistic regression analysis.

RESULTS

Total cholesterol, TGs, LDL-C and Cr were significantly higher in CKD patients than in non-CKD patients. In contrast, the estimated glomerular filtration rate (eGFR) and AREase activity were significantly lower in CKD patients than in non-CKD patients (P < .05). The genotype and allele frequencies of the PON1 L55M and Q192R polymorphisms were not significantly different between CKD and non-CKD patients. Multivariate logistic regression analysis showed no association between the PON1 L55M and Q192R polymorphisms and CKD in T2DM. In addition, among all patients, patients with the PON1 LM genotype had significantly lower PONase activity than those with the LL genotype (P < .05). Among all patients, CKD patients and non-CKD patients, those with the PON1 RR genotype had significantly higher PONase activity but lower AREase activity than patients with the QR and QQ genotypes (P < .05).

CONCLUSIONS

PON1 activity was influenced by the PON1 L55M and Q192R polymorphisms. However, the PON1 L55M and Q192R polymorphisms may not be considered genetic biomarkers for CKD in T2DM.

What's the Optimal Lipids Level for Dialysis Patients? A Cohort Study from a Chinese Dialysis Center in a University Hospital

BACKGROUND

With lipid level being a major contributing factor for cardiovascular health, the high cardiovascular mortality among dialysis patients has raised substantial concerns in regard to the optimal lipid level in these patient population.

OBJECTIVE

To explore the optimal lipid level for the survival of dialysis patients.

METHODS

The lipid profile was measured for each patient. All participants were followed throughout the course of the study. Cox proportional hazards analysis was performed to analyze the prognostic value of lipid level on the survival of these patients.

RESULTS

In our study that included 311 stable maintenance dialysis patients, 54.98% of the participants had LDL-C level ≥100 mg/dl and 82.91% of the patients with triglycerides ≥200 mg/dl had non-HDL level ≥130 mg/dl. During the follow-up period of 48.0 (18.0, 55.5) months, 149 (47.91%) participants died. Among those who died, 59 patients died of cardiovascular disease (CVD) and 33 patients died of ischemic CVD (12.0, 4.7, and 2.7 events per 100 patient-years, respectively). Patients with LDL-C 100-130 mg/dl or non-HDL 130-160 mg/dl had a lower all-cause mortality rate than those who did not meet these criteria. After adjusting for the traditional and ESRD-related risk factors, non-HDL was found to be the independent risk factor for the all-cause mortality. Compared to those patients with non-HDL 130-160 mg/dl, patients with non-HDL <100 mg/dl, 100-130 mg/dl, 160-190 mg/dl, or ≥190 mg/dl all had higher all-cause mortality: HR (95% CI) 3.207 (1.801, 5.713), 2.493 (1.485, 4.184), 2.476 (1.423, 4.307), and 1.917 (1.099, 3.345), respectively. There were no differences in nutrition, comorbidity, and inflammation indices among the patients with different non-HDL groups. However, patients with non-HDL of 130-160 mg/dl had the lowest corrected calcium and calcium phosphate product values as compared with other non-HDL groups.

CONCLUSION

Our study demonstrated that non-HDL 130-160 mg/dl might be the most appropriate lipid level in our dialysis patients. Our follow-up data also showed that patients with higher lipid level had poorer prognosis, just as in the general population.

Kidney aging--inevitable or preventable?

The aging process affects all organs, including the kidneys. As part of this process, progressive scarring and a measurable decline in renal function occur in most people over time. The improved understanding of the processes that can lead to and/or hasten scarring and loss of renal function over time parallels advances in our understanding of the aging process. Clinical factors, including hypertension, diabetes mellitus, obesity, abnormal lipid levels and vitamin D deficiency, have been associated with increasing renal sclerosis with age. In addition, tissue factors such as angiotensin II, advanced glycation end products, oxidative stress and Klotho are associated with renal aging. These associations and possible interventions, including the control of blood pressure, blood sugar, weight, diet and calorie restriction might make renal aging more preventable than inevitable.

Application of GC/MS-based metabonomic profiling in studying the lipid-regulating effects of Ginkgo biloba extract on diet-induced hyperlipidemia in rats

AIM

To evaluate the lipid-regulating effects of extract from Ginkgo biloba leaves (EGB) using pharmacological methods and metabonomic profiling in a rat model of diet-induced hyperlipidemia.

METHODS

EGB was orally administered at a dose level of 40 mg/kg in both the EGB-prevention and -treatment groups. All rat samples obtained were examined for known and potential biomarkers and enzyme activity using commercial assay kits and GC/MS-based metabonomic profiling coupled with principal component analysis (PCA).

RESULTS

The data obtained from the assay kits indicated that EGB reduced total cholesterol and low density lipoprotein cholesterol levels and increased high density lipoprotein cholesterol levels in rat plasma obtained from both the EGB-prevention and -treatment groups compared with those of the diet-induced hyperlipidemia group. EGB also increased the activities of lipoprotein lipase and hepatic lipase and excretion of fecal bile acid in rats from the EGB-prevention and-treatment groups. Using GC/MS-based metabonomic analysis, more than 40 endogenous metabolites were identified in rat plasma. PCA of rat plasma samples obtained using GC/MS produced a distinctive separation of the four treatment groups and sampling points within each group. Metabolic changes during hyperlipidemia formation and improvement resulting from EGB treatment were definitively monitored with PCA score plots. Furthermore, elevated levels of sorbitol, tyrosine, glutamine and glucose, and decreased levels of citric acid, galactose, palmitic acid, arachidonic acid, acetic acid, cholesterol, butyrate, creatinine, linoleate, ornithine and proline, were observed in the plasma of rats treated with EGB.

CONCLUSION

EGB exerts multi-directional lipid-lowering effects on the rat metabonome, including limitation of the absorption of cholesterol, inactivation of HMGCoA and favorable regulation of profiles of essential polyunsaturated fatty acid (EFA). Further experiments are warranted to explore the mechanisms of action underlying the lipid-regulating effects of EGB against hyperlipidemia.

Effect of LDL cholesterol and treatment with losartan on end-stage renal disease in the RENAAL study

Renal pathology and dyslipidemia commonly coexist. Treatments that lower albuminuria/proteinuria may lower lipids, but it is not known whether lipid lowering independent of lessening albuminuria/proteinuria slows progression of kidney disease. We examined the association between LDL cholesterol levels and treatment with losartan on end-stage renal disease (ESRD). Lipid levels and albuminuria measurements were obtained at baseline and at year 1 in a post hoc analysis from the Reduction of Endpoints in NIDDM with the Angiotensin II Antagonist Losartan (RENAAL) study, which compared the effects of losartan- versus placebo-based antihypertensive therapy in patients with type 2 diabetes and nephropathy. LDL cholesterol lowering was associated with a lower risk of ESRD; however, this seemed to be largely an association with the reduction in albuminuria.

D-4F reduces EO6 immunoreactivity, SREBP-1c mRNA levels, and renal inflammation in LDL receptor-null mice fed a Western diet

LDL receptor-null (LDLR(-/-)) mice on a Western diet (WD) develop endothelial dysfunction and atherosclerosis, which are improved by the apolipoprotein A-I (apoA-I) mimetic peptide D-4F. Focusing on the kidney, LDLR(-/-)mice were fed a WD with D-4F or the inactive control peptide scrambled D-4F (ScD-4F) added to their drinking water. The control mice (ScD-4F) developed glomerular changes, increased immunostaining for MCP-1/CCL2 chemokine, increased macrophage CD68 and F4/80 antigens, and increased oxidized phospholipids recognized by the EO6 monoclonal antibody in both glomerular and tublo-interstitial areas. All of these parameters were significantly reduced by D-4F treatment, approaching levels found in wild-type C57BL/6J or LDLR(-/-) mice fed a chow diet. Sterol-regulatory element binding protein-1c (SREBP-1c) mRNA levels and triglyceride levels were elevated in the kidneys of the control mice (ScD-4F) fed the WD compared with C57BL/6J and LDLR(-/-) mice on chow (P < 0.001 and P < 0.001, respectively) and compared with D-4F-treated mice on the WD (P < 0.01). There was no significant difference in plasma lipids, lipoproteins, glucose, blood pressure, or renal apoB levels between D-4F- and ScD-4F-treated mice. We conclude that D-4F reduced renal oxidized phospholipids, resulting in lower expression of SREBP-1c, which, in turn, resulted in lower triglyceride content and reduced renal inflammation.