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

Effects of Nostoc sphaeroids Kütz polysaccharide on renal fibrosis in high-fat mice

In this study, we investigated the effects of Nostoc sphaeroids Kütz polysaccharide (NSKP) on renal fibrosis in high‐fat mice. ApoE^−/− male mice were randomly divided into four groups: control (Cont) group, high‐fat diet (HFD) group, HFD+0.4 g/kg BW NSKP, and HFD+0.8 g/kg BW NSKP (NSKP groups). The Cont was fed a standard diet. The HFD group was fed HFD. Every day, NSKP groups were fed HFD, as well as given 0.4 g/kg BW or 0.8 g/kg BW NSKP. After 22 weeks, the serum biochemical indices (TC, TG, LDL‐C, HDL‐C, GLU, BUN, and SCR) were measured. For the kidney, the histopathological sections were observed and analyzed, and inflammatory factors and markers of renal fibrosis were measured. For the NSKP groups, the serum TC, TG, LDL‐C, BUN, and SCR were decreased, HDL‐C significantly increased compared with the HFD group. The protein expressions of TNF‐α, IL‐1β, and TGF‐β1 were significantly downregulated. The α‐SMA in renal cortex was decreased, and the mRNA expression of Col‐I and Col‐IV in renal collagen fibers was downregulated. To sum up, NSKP reduced the blood lipid of HFD mice, downregulated the inflammation of kidney, inhibited the expression of collagen fiber, and improved the renal fibrosis caused by long‐term lipid metabolism disorder.

Recent Progress on Lipid Intake and Chronic Kidney Disease

The incidence of chronic kidney disease (CKD) is associated with major abnormalities in circulating lipoproteins and renal lipid metabolism. This article elaborates on the mechanisms of CKD and lipid uptake abnormalities. The viewpoint we supported is that lipid abnormalities directly cause CKD, resulting in forming a vicious cycle. On the theoretical and experiment fronts, this inference has been verified by elaborately elucidating the role of lipid intake and accumulation as well as their influences on CKD. Taken together, these findings suggest that further understanding of lipid metabolism in CKD may lead to novel therapeutic approaches.

Cholesterol Disturbances and the Role of Proper Nutrition in CKD Patients

Chronic kidney disease (CKD) is a widespread disease with increasing prevalence in the modern society. Lipid disturbances are common in this group of patients. In most patients with CKD atherogenic dyslipidemia is observed. Dyslipidemia in patients with renal diseases increases the risk of cardiovascular diseases and it accelerates the progression of chronic kidney disease to its end stage. The amelioration of dyslipidemia and the lowering of oxidative stress, inflammatory processes, insulin sensitivity and remnant lipoproteins levels may lead to the reduction in cardiovascular burden. Nutritional interventions can strengthen the beneficial effect of treatment and they play an important role in the preservation of overall well-being of the patients with CKD since the aim of appropriate diet is to reduce the risk of cardiovascular events, prevent malnutrition, and hamper the progression of kidney disease. The management of dyslipidemia, regardless of the presence of chronic kidney disease, should be initiated by the introduction of therapeutic lifestyle changes. The introduction of diet change was shown to exert beneficial effect on the lipid level lowering that reaches beyond pharmacological therapy. Currently available evidence give the impression that data on dietary interventions in CKD patients is not sufficient to make any clinical practice guidelines and is of low quality.

Cyanate Induces Oxidative Stress Injury and Abnormal Lipid Metabolism in Liver through Nrf2/HO-1

Chronic kidney disease (CKD) is problem that has become one of the major issues affecting public health. Extensive clinical data suggests that the prevalence of hyperlipidemia in CKD patients is significantly higher than in the general population. Lipid metabolism disorders can damage the renal parenchyma and promote the occurrence of cardiovascular disease (CVD). Cyanate is a uremic toxin that has attracted widespread attention in recent years. Usually, 0.8% of the molar concentration of urea is converted into cyanate, while myeloperoxidase (MPO) catalyzes the oxidation of thiocyanate to produce cyanate at the site of inflammation during smoking, inflammation, or exposure to environmental pollution. One of the important physiological functions of cyanate is protein carbonylation, a non-enzymatic post-translational protein modification. Carbamylation reactions on proteins are capable of irreversibly changing protein structure and function, resulting in pathologic molecular and cellular responses. In addition, recent studies have shown that cyanate can directly damage vascular tissue by producing large amounts of reactive oxygen species (ROS). Oxidative stress leads to the disorder of liver lipid metabolism, which is also an important mechanism leading to cirrhosis and liver fibrosis. However, the influence of cyanate on liver has remained unclear. In this research, we explored the effects of cyanate on the oxidative stress injury and abnormal lipid metabolism in mice and HL-7702 cells. In results, cyanate induced hyperlipidemia and oxidative stress by influencing the content of total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL), superoxide dismutase (SOD), catalase (CAT) in liver. Cyanate inhibited NF-E2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), and the phosphorylation of adenosine 5'monophosphate-activated protein kinase (AMPK), activated the mTOR pathway. Oxidative stress on the cells reduced significantly by treating with TBHQ, an antioxidant, which is also an activator of Nrf2. The activity of Nrf2 was rehabilitated and phosphorylation of mTOR decreased. In conclusion, cyanate could induce oxidative stress damage and lipid deposition by inhibiting Nrf2/HO-1 pathway, which was rescued by inhibitor of Nrf2.

Bio-evaluation of functional date bars using rats as model organism against hypercholesterolemia

Background

The present research project was designed to evaluate the cholesterol lowering potential of different date varieties including one exotic (Ajwa) and three Pakistani varieties (Aseel, Khudravi, Hallawi).

Methods

The albino rats were divided into six groups on the basis of different diets which includes, control having basal diet, high cholesterol high sucrose diet, high cholesterol high sucrose diet plus Khudravi dates, high cholesterol high sucrose diet plus Hallawi dates, high cholesterol high sucrose diet plus Aseel dates, high cholesterol high sucrose diet plus Ajwa dates to evaluate maximum cholesterol lowering potential of each date variety.

Results

The results showed that Hallawi and Ajwa have lower crude fiber content as 2.02 ± 0.03% and 2.43 ± 0.04% however, lowest crude fat content (0.26 ± 0.01%) was also observed in ajwa. Mineral profile depicted that sodium (9.50–18.00 mg/100 g) was found to be in lesser amount among all varieties whereas, higher amount of potassium (465.00 to 887.20 mg/100 g) depicted that it is suitable for people having hypertension. Higher amount of reducing sugar was also observed in ajwa (79.45 ± 1.22%) followed by Hallawi (77.68 ± 1.42%). Total phenolic contents were found higher in Aseel (291.36 mg/100 g) whereas, minimum was observed in Khudravi (232.64 mg/100 g). Furthermore, date varieties were also examined rat modeling to evaluate their maximum cholesterol lowering efficiency. Ajwa and Hallawi were observed to suppress the cholesterol efficiently as 110 mg/dL and 103 mg/dL respectively. On the basis of chemical profiling and other parameters, two date varieties Ajwa and Hallawi showed almost similar results and found to have maximum serum cholesterol, LDL and triglyceride reduction potential with good kidney and liver functions. Functional date bar was also developed by using Hallawi variety andsubjected to sensory evaluation.

Conclusion

In nutshell, Hallawi date variety was considered as better cholesterol lowering potential among other indigenous varieties and very close to Ajwa variety. So that Hallawi can be used to suppress the deadly effects of obesity and allied discrepancies particularly hypercholesterolemia.

Mitochondrial dysfunction in diabetic kidney disease

Globally, diabetes is the leading cause of chronic kidney disease and end-stage renal disease, which are major risk factors for cardiovascular disease and death. Despite this burden, the factors that precipitate the development and progression of diabetic kidney disease (DKD) remain to be fully elucidated. Mitochondrial dysfunction is associated with kidney disease in nondiabetic contexts, and increasing evidence suggests that dysfunctional renal mitochondria are pathological mediators of DKD. These complex organelles have a broad range of functions, including the generation of ATP. The kidneys are mitochondrially rich, highly metabolic organs that require vast amounts of ATP for their normal function. The delivery of metabolic substrates for ATP production, such as fatty acids and oxygen, is altered by diabetes. Changes in metabolic fuel sources in diabetes to meet ATP demands result in increased oxygen consumption, which contributes to renal hypoxia. Inherited factors including mutations in genes that impact mitochondrial function and/or substrate delivery may also be important risk factors for DKD. Hence, we postulate that the diabetic milieu and inherited factors that underlie abnormalities in mitochondrial function synergistically drive the development and progression of DKD.

The evolving understanding of the contribution of lipid metabolism to diabetic kidney disease

Although diabetes is mainly diagnosed based on elevated glucose levels, dyslipidemia is also observed in these patients. Chronic kidney disease (CKD), a frequent occurrence in patients with diabetes, is associated with major abnormalities in circulating lipoproteins and renal lipid metabolism. At baseline, most renal epithelial cells rely on fatty acids as their energy source. CKD, including that which occurs in diabetes, is characterized by tubule epithelial lipid accumulation. Whether this is due to increased uptake or greater local fatty acid synthesis is unknown. We have recently shown that CKD also leads to decreased fatty acid oxidation, which might be an additional mechanism leading to lipid accumulation. Defective fatty acid utilization causes energy depletion resulting in increased apoptosis and dedifferentiation, which in turn contributes to fibrosis and CKD progression. Enhanced fatty acid oxidation in the kidney induced by fenofibrate, a peroxisomal proliferator-activated receptor (PPAR)-α agonist, showed benefit in mouse models of CKD. Fenofibrate treatment also reduced albuminuria in patients with diabetes in multiple clinical trials. Taken together, these findings suggest that further understanding of lipid metabolism in diabetic kidney disease may lead to novel therapeutic approaches.

Statins of high versus low cholesterol-lowering efficacy and the development of severe renal failure

BACKGROUND

The objective of this nationwide retrospective cohort study was to examine the renal outcomes of HMG-CoA reductase inhibitor (statin) initiators.

METHODS

The patients who started to take statins with high cholesterol-lowering efficacy (atorvastatin and rosuvastatin) and low efficacy (lovastatin, simvastatin, pravastatin, and fluvastatin) between 1 January 2001 and 31 December 2008 were identified from the Taiwan National Health Insurance claims database. The outcome of interest was severe renal failure, defined as the composite endpoint of hemodialysis, peritoneal dialysis, and kidney transplantation. A proportional hazard regression model was applied to estimate the incidence ratio between the two groups, adjusted for the propensity scores based upon baseline characteristics.

RESULTS

Among of the 26,007 and 42,249 statin initiators, the crude incidence rate for developing severe renal failure was 0.65 and 0.46 per 100 person-years for the high-efficacy and low-efficacy groups, respectively. Despite that these two groups had comparable risk for myocardial infarction (hazard ratio: 1.06, 95%CI: 0.92–1.21), there was a 13% increased hazard for developing severe renal failure in the rosuvastatin and atorvastatin initiators (hazard ratio: 1.13, 95%CI: 1.02–1.26). The increased risk associated with these two statins was consistent across different risk groups (diabetes, chronic kidney disease, and ischemic heart disease).

CONCLUSIONS

Statins with high cholesterol-lowering efficacy might increase the risk for developing severe renal failure. An alternative explanation is that the renal risk cannot be ameliorated as much as cardiovascular risk. Further follow-up studies or meta-analyses are needed to solve the controversy.

The effect of chronic kidney disease on total hip arthroplasty

Patients with chronic kidney disease (CKD) undergoing total hip arthroplasty (THA) were evaluated for risk of revision, surgical site infection (SSI), thromboembolic events, mortality and readmission. 20,720 primary TKA cases were included (smaller sample for readmission evaluation, N = 9322). The prevalence of CKD among THA patients was 6.1% (N = 1269). After adjustment for age, gender, race, general health, and diabetes, CKD patients were at 1.4 (95% confidence interval 1.1-1.8) increased risk of readmission within 90 days. The adjusted risks for revision (overall, aseptic, and septic), SSI (deep and superficial), deep vein thrombosis, pulmonary embolism, and mortality (30-day, 90-day, ever) were not significantly different between patients with CKD and those without CKD. However, increased risk for 90-day readmission underscores that CKD patients are a fundamentally different population of patients.

Degrees of kidney disease in nigerian adults with sickle-cell disease

OBJECTIVE

To study degrees of chronic kidney disease (CKD) using creatinine clearance in adult Nigerian patients with sickle-cell disease (SCD).

METHODS

One hundred SCD patients, made up of 79 HbSS (homozygous haemoglobin S) patients and 21 HbSC (heterozygous haemoglobins S and C) patients, were investigated prospectively, along with 50 normal controls. Their sociodemographic data, weight and drug history were documented. Each participant underwent dipstick urinalysis, and creatinine clearance was calculated following a 24-hour urine collection and serum creatinine measurement. They were categorized into stages of CKD based on the creatinine clearance.

RESULTS

Of the 79 HbSS patients, 14 (18%), 28 (35%), 33 (42%) and 4 (5%) had stage 1, 2, 3 and 4 CKD, respectively. In the HbSC group, 3 (14%), 9 (43%) and 9 (43%) patients had stage 1, 2 and 3 CKD, respectively. Proteinuria was noted in 16 (20%) HbSS patients but not in any of the HbSC patients. Of the subjects aged ≤24 years (n = 49), 9 (18%), 18 (37%), 21 (43%) and 1 (2%) had stage 1, 2, 3 and 4 CKD, respectively. Of those aged >24 years (n = 51), 8 (16%), 19 (37%), 21 (41%) and 3 (6%) had stage 1, 2, 3 and 4 CKD, respectively. None of the subjects had stage 5 CKD.

CONCLUSION

In this study, the adult subjects with SCD had various degrees of CKD. Adequate follow-up and active intervention are advocated to delay the onset of end-stage nephropathy.

Can total knee arthroplasty be safely performed in patients with chronic renal disease?

BACKGROUND AND PURPOSE

The prevalence of chronic renal disease (CRD) is rising worldwide. Patients with CRD are more likely to have associated medical problems and are at greater risk of postoperative morbidity and mortality. We evaluated patient characteristics and risk of early revision, surgical site infection (SSI), thromboembolic events, mortality, and re-admission of patients with CRD undergoing total knee arthroplasty (TKA). We hypothesized that this patient population would have higher rates of complications.

PATIENTS AND METHODS

We conducted a retrospective analysis of data that had been prospectively collected by a Total Joint Replacement Registry. All primary TKAs performed from 2005 through 2010 were included. 41,852 primary TKA cases were evaluated, of which 2,686 (6.4%) TKA procedures had been performed in CRD patients. Patient characteristics, comorbidities, and general health status were evaluated. Cox proportional hazard regressions and logistic regressions were used to evaluate the association of CRD with outcomes while adjusting for confounding variables. Results - The mean age of the CRD cohort was 67 years and approximately two-thirds of the patients were female. The median follow-up time was 2.1 years. Compared to TKA patients without CRD the CRD patients were older, had poorer general health, and had a higher prevalence of comorbidities. They had a higher incidence of deep SSI (0.9% vs. 0.7%), superficial SSI (0.5% vs. 0.3%), deep vein thrombosis (0.6% vs. 0.4%), any-time mortality (4.7% vs. 2.4%), 90-day mortality (0.4% vs. 0.2%), and 90-day re-admission (10% vs. 6.0%) than patients without CRD. However, after adjustment for confounding variables, CRD patients were at 1.9 times (95% CI: 1.1-3.5) increased risk of superficial SSI, 1.3 times (CI: 1.1-1.6) increased risk of re-admission within 90 days, and 1.5 times (CI: 1.2-1.8) increased risk of mortality at any point after the procedure. The risks of all other complications were not statistically significantly different in patients with CRD compared to patients without CRD.

CONCLUSIONS

CRD patients undergoing TKA have more comorbidities and a higher risk for superficial SSI, 90-day re-admission, and any-time mortality.

Activation of renin-angiotensin system is involved in dyslipidemia-mediated renal injuries in apolipoprotein E knockout mice and HK-2 cells

Background

Dyslipidemia and activation of renin-angiotensin system (RAS) contribute to the progression of chronic kidney disease (CKD). This study investigated possible synergistic effects of intrarenal RAS activation with hyperlipidemia in renal injuries.

Methods

Apolipoprotein knockout mice were fed with normal chow diet (control) or high fat diet (HF group) for eight weeks. Human proximal tubular epithelial cell line (HK-2) was treated without (control) or with cholesterol (30 μg/ml) plus 25-hydroxycholesterol (1 μg/ml) (lipid group) for 24 hours. The plasma lipid profile and RAS components were determined by clinical biochemistry assay and radiommunoassay, respectively. Collagen deposition in kidneys was evaluated by Masson-staining. The gene and protein expressions of molecules involved in RAS components and biomarkers of epithelial mesenchymal transition (EMT) were examined by real-time PCR, immunochemical staining, and Western blot.

Results

The mice fed with high-fat diet showed significant hyperlipidemia with collagen deposition in renal tubular interstitium compared to controls. The plasma levels of renin, angiotensin I, and angiotensin II were no difference in two groups. However, the kidneys of HF group showed up-regulated RAS components, which were positively associated with increased plasma levels of triglyceride, total cholesterol, and LDL. These effects were further confirmed by in vitro studies. Lipid loading induced HK-2 cells underwent EMT, which was closely associated with the increased expressions of intracellular RAS components.

Conclusions

Local RAS activation was involved in hyperlipidemia-mediated renal injuries, suggesting that there are synergistic effects resulting from RAS activation with hyperlipidemia that accelerates the progression of CKD.

Treatment of chronic hemodialysis patients with low-dose fenofibrate effectively reduces plasma lipids and affects plasma redox status

Dyslipidemia is common in chronic hemodialysis patients and its underlying mechanism is complex. Hemodialysis causes an imbalance between antioxidants and production of reactive oxygen species, which induces the oxidative stress and thereby may lead to accelerated atherosclerosis. Statins have been found to be little effective in end-stage kidney disease and other lipid-lowering therapies have been only scarcely studied. The study aimed to assess the effect of low-dose fenofibrate therapy on plasma lipids and redox status in long-term hemodialysis patients with mild hypertriglyceridemia.

Twenty seven chronic hemodialysis patients without any lipid-lowering therapy were included in a double-blind crossover, placebo-controlled study. The patients were randomized into two groups and were given a sequence of either 100 mg of fenofibrate per each hemodialysis day for 4 weeks or placebo with a week-long wash-out period between treatment periods. Plasma lipids, high sensitive C-reactive protein (CRP), urea, creatinine, electrolytes, phosphocreatine kinase (CK), GOT, GPT and plasma thiols (total and free glutathione, homocysteine, cysteine and cysteinylglycine) were measured at baseline and after each of the study periods. Plasma aminothiols were measured by reversed phase HPLC with thiol derivatization with 2-chloro-1-methylquinolinium tetrafluoroborate.

Fenofibrate therapy caused a significant decrease of total serum cholesterol, LDL cholesterol and triglycerides and an increase of HDL cholesterol. The treatment was well tolerated with no side-effects but there was a small but significant increase of CK not exceeding the upper limit of normal range. There were no changes of serum CRP, potassium, urea, and creatinine and liver enzymes during the treatment. Neither total nor total free cysteinylglycine and cysteine changed during the study but both total and free glutathione increased during the therapy with fenofibrate and the same was observed in case of plasma homocysteine.

The study shows that a treatment with reduced fenofibrate dose is safe and effective in reducing serum triglycerides and cholesterol in chronic dialysis patients and may shift plasma aminothiol balance towards a more antioxidative pattern.