HMG CoA reductase inhibitors and renoprotection: the weight of the evidence

Elevated serum cholesterol levels are associated with proteinuria over 0.5 g/day in premenopausal women with systemic lupus erythematosus

Background: Systemic lupus erythematosus (SLE) commonly occurs in premenopausal women and is associated with elevated estrogen levels. Patients with SLE may have abnormal serum triglyceride (TG) levels, and lipid reportedly promotes kidney damage in patients with nephrosis. Since estrogen regulates lipid levels, we investigated the serum lipid levels of premenopausal women with SLE and their relationship with proteinuria. Methods: This cross-sectional study included 123 premenopausal women with SLE (SLE group), who were classified into 24-h urine protein exceeding 0.5 g (24 h-UPRO > 0.5 g, n = 22) and 24 h-UPRO ≤ 0.5 g (n = 101) subgroups, and 100 similarly aged healthy women (control group). Clinical characteristics and biomarker levels were compared between these groups. The associated factors of proteinuria over 0.5 g/day were evaluated using multivariate logistic regression. A receiver operating characteristic (ROC) curve was plotted to assess the cholesterol (CH) cut-off associated with increased development of proteinuria over 0.5 g/day. Results: The SLE group had significantly higher serum TG levels than that of control group. 24 h-UPRO were significantly correlated with serum creatinine, CH, TG, and uric acid levels. Serum CH level was the greatest associated factor for proteinuria over 0.5 g/day. The area under the ROC curve was 0.843, with a CH cut-off of 4.58 mmol/L. Patients with serum CH above 4.58 mmol/L had a higher proportion of type IV LN, but with no statistical difference. Conclusions: In premenopausal SLE patients, serum TG levels were higher than in healthy women, and serum CH levels were the primary associated factor for proteinuria over 0.5 g/day. Proteinura over 0.5 g/day may occur in women with SLE with serum CH levels >4.58 mmol/L. CH levels may be useful for predicting proteinuria.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Protective effects of probucol on Ox-LDL-induced epithelial-mesenchymal transition in human renal proximal tubular epithelial cells via LOX‑1/ROS/MAPK signaling

Oxidized low-density lipoprotein (Ox-LDL), as a strong oxidant, results in renal injury through multiple mechanisms. The aim of the present study was to determine the injury effects of Ox‑LDL and the potential protective effects of the antioxidant reagent probucol on epithelial‑mesenchymal transition (EMT) in human renal proximal tubular epithelial cells (HK‑2) and to further explore the role and interrelation of lectin‑like oxidized low‑density lipoprotein receptor‑1 (LOX‑1), reactive oxygen species (ROS) and mitogen‑activated protein kinase (MAPK) pathway. In the present study, concentrations of 0‑100 µg/ml Ox‑LDL were used to induce HK‑2 cell EMT. Then, probucol (20 µmol/l) and the LOX‑1 inhibitor, polyinosinic acid (250 µg/ml), were also used to pretreat HK‑2 cells. Intracellular ROS activity was evaluated using the specific probe 2',7'‑dichlorodihydrofluorescein diacetate (DCFH‑DA). Concentration of nitric oxide (NO) was determined using a biochemical colorimetric method. Expression of E‑cadherin, α‑smooth muscle actin (SMA), LOX‑1, NADPH oxidase 4 (NOX4), cytochrome b‑245 α chain (p22phox), extracellular signal‑regulated kinase (ERK), and p38 MAPK protein levels were examined by western blotting. The results revealed that Ox‑LDL induced the expression of LOX‑1 and α‑SMA and reduced the expression of E‑cadherin in a dose‑dependent manner, and these effects were inhibited by polyinosinic acid or probucol pretreatment. Stimulation with 50 µg/ml Ox‑LDL induced the expression of NOX4 and p22phox and increased intracellular ROS activity, but NO production in the cell supernatants was not affected. The Ox‑LDL‑mediated increases in Nox4 and p22phox expression and in ROS activity were inhibited by probucol pretreatment. Further investigations into the underlying molecular pathways demonstrated that ERK and p38 MAPK were activated by Ox‑LDL stimulation and then inhibited by probucol pretreatment. The findings of the present study therefore suggest that Ox‑LDL induced EMT in HK‑2 cells, the mechanism of which may be associated with LOX‑1‑related oxidative stress via the ERK and p38 MAPK pathways. Notably, pretreatment with probucol inhibited the Ox‑LDL‑induced oxidative stress by reducing the expression of LOX‑1, and blocked the progression of EMT.

Chronic kidney disease: a new look at pathogenetic mechanisms and treatment options

The concept of renoprotection has evolved significantly, driven by improved understanding of the pathophysiology of chronic kidney disease (CKD) and the advent of novel treatment options. Glomerular hyperfiltration, hypertension and proteinuria represent key mediators of CKD progression. It is increasingly recognized that proteinuria may actually be pathological and etiological in CKD progression and not just symptomatic. It initiates a sequence of events involving activation of proinflammatory and profibrotic signaling pathways in proximal tubular epithelial cells with transmission of the disease to the tubulointerstitium and progression to end-stage kidney disease (ESKD). Although the etiology and epidemiology of pediatric CKD differs to that in adults, studies in the various animal models of kidney disease, from obstructive uropathy to glomerulonephritis, have revealed that many common proinflammatory and profibrotic pathways are induced in progressive proteinuric CKD, irrespective of the primary disease. This pathomechanistic overlap therefore translates into the potential for common treatment targets for a wide spectrum of kidney diseases. In this review we therefore discuss the experimental and clinical evidence for an array of prospective future drug treatments of CKD progression. While conceptually promising, clear definitive evidence beyond preclinical data does not exist for many of these treatments, and others are limited by serious adverse effects. More studies are needed before general recommendations can be given.

Atorvastatin reduces proteinuria in non-diabetic chronic kidney disease patients partly via lowering serum levels of advanced glycation end products (AGEs)

There is accumulating evidence that advanced glycation end products (AGEs) play a role in the development and progression of chronic kidney disease (CKD). We have previously found that atorvastatin treatment significantly reduces serum levels of AGEs in type 2 diabetic patients and subjects with non-alcoholic steatohepatitis in a cholesterol loweringindependent manner. In this study, we examined whether atorvastatin could reduce proteinuria partly via reduction of serum levels of AGEs in non-diabetic CKD patients. Ten non-diabetic normotensive stage I or II CKD patients with dyslipidemia were enrolled. Patients were treated with atorvastatin (10 mg/day) for one year. All subjects underwent determination of blood chemistries, proteinuria and serum levels of AGEs at baseline and after one year. Atorvastatin treatment for one year significantly decreased circulating levels of total cholesterol, LDL cholesterol, triglycerides and AGEs, while it increased HDL cholesterol levels. Further, although atorvastatin treatment did not affect estimated glomerular filtration rate, it significantly reduced proteinuria. In univariate analyses, proteinuria levels were correlated with total cholesterol, LDL cholesterol, triglycerides, HDL cholesterol (inversely) and AGEs. Multiple stepwise regression analysis revealed that AGE level was a sole independent correlate of proteinuria. In this initial examination of the patients in this study, our present study suggests that atorvastatin could decrease proteinuria in non-diabetic CKD patients with dyslipidemia partly via reduction of serum levels of AGEs. Atorvastatin may have AGE-lowering effects in CKD patients as well that could contribute to renoprotective properties of this agent.