Pravastatin suppress superoxide and fibronectin production of glomerular mesangial cells induced by oxidized-LDL and high glucose

Estimated small dense low-density lipoprotein-cholesterol and the risk of kidney and cardiovascular outcomes in diabetic kidney disease

AIMS

This study aimed to investigate the correlations between estimated small dense low-density lipoprotein-cholesterol (esd-LDL-c) and the development of end-stage kidney disease (ESKD), cardiovascular mortality, and all-cause mortality in individuals with diabetic kidney disease (DKD) or diabetes mellitus (DM) concomitant chronic kidney disease (CKD).

METHODS

We analyzed the data from a biopsy-proven DKD cohort conducted at West China Hospital of Sichuan University between 2009 and 2021 (the DKD cohort) and participants with DM and CKD in the National Health and Nutrition Examination Survey (NHANES) 2011-2014 (the NHANES DM-CKD cohort). Cox regression analysis was also used to estimate associations between esd-LDL-c and the incidence of ESKD, cardiovascular mortality, and all-cause mortality.

RESULTS

There were 175 ESKD events among 338 participants in the DKD cohort. Patients were divided into three groups based on esd-LDL-c tertiles (T1 < 33.7 mg/dL, T2 ≥ 33.7 mg/dL to <45.9 mg/dL, T3 ≥ 45.9 mg/dL). The highest tertile of esd-LDL-c was associated with ESKD (adjusted HR 2.016, 95% CI 1.144-3.554, p = .015). Furthermore, there were 99 deaths (39 cardiovascular) among 293 participants in the NHANES DM-CKD cohort. Participants were classified into three groups in line with the tertile values of esd-LDL-c in the DKD cohort. The highest tertile of esd-LDL-c was associated with cardiovascular mortality (adjusted HR 3.95, 95% CI 1.3-12, p = .016) and all-cause mortality (adjusted HR 2.37, 95% CI 1.06-5.32, p = .036).

CONCLUSIONS

Higher esd-LDL-c was associated with increased risk of ESKD in people with biopsy-proven DKD, and higher cardiovascular and all-cause mortality risk among those with DM-CKD.

Association of remnant cholesterol with renal function and its progression in patients with type 2 diabetes related chronic kidney disease

BACKGROUND

The association of Remnant cholesterol (RC) with renal function and its progression in patients with Type 2 diabetes (T2DM) related chronic kidney disease (CKD) remains unclear.

METHODS

8,678 patients with T2DM-related CKD were included in cross-sectional analysis, and 6,165 patients were enrolled in longitudinal analysis and followed up for a median of 36.0 months. The outcomes were renal composite endpoint event and rapid progression of renal function.

RESULTS

24.54% developed a renal composite endpoint event, and 27.64% rapid progression of renal function. RC levels above 0.56 mmol/L independently increased the risk of both renal composite endpoint (HR, 1.17; 95% CIs, 1.03-1.33) and rapid progression of renal function (OR, 1.17; 95% CIs, 1.01- 1.37). TG levels above 1.65 mmol/L only increased the risk of renal composite endpoint (HR, 1.16; 95% CIs, 1.02 -1.32). TC levels above 5.21 mmol/L increased the risk of renal composite endpoint (HR, 1.14; 95% CIs, 1.01-1.29) only in patients with proteinuria≥0.5g/d. Conversely, HDL-C levels below 1.20 mmol/L or above 1.84 mmol/L increased the risk of rapid progression of renal function (OR, 0.88; 95% CIs, 0.70 -0.99) in patients with proteinuria<0.5g/d (all P<0.05).

CONCLUSION

In patients with T2DM-related CKD, RC was an independent risk factor for progression of renal function, and maintaining it below 0.56 mmol/L could reduce the risk of renal function progression.

Celastrol attenuates ox-LDL-induced mesangial cell proliferation via suppressing NLRP3 inflammasome activation

Mesangial cell (MC) proliferation is one of the important pathological features of obesity-associated nephropathy with unknown etiology. Excessive MC proliferation can cause glomerulosclerosis and renal function loss. Thus, targeting MC proliferation may be a potential strategy for the treatment of obesity-associated kidney disease. The present study was undertaken to investigate the role of celastrol in MC proliferation induced by ox-LDL, as well as the potential mechanisms. Following ox-LDL treatment, MC proliferation was induced and the NLRP3 inflammasome was activated, as evidenced by increased NLRP3 levels, caspase 1 activity, and IL-18 and IL-1β release. Significantly, NLRP3 siRNAs inhibited MC proliferation and delayed cell cycle progression, as indicated by the cell cycle assay and the expression of cyclin A2 and cyclin D1. Given the anti-inflammatory effect of celastrol, we pretreated MCs with celastrol before ox-LDL treatment. As expected, celastrol pretreatment strikingly inhibited NLRP3 inflammasome activation and MC proliferation triggered by ox-LDL. In summary, celastrol potently blocked ox-LDL-induced MC proliferation, possibly by inhibiting NLRP3 inflammasome activation. These findings also suggest that celastrol may be a potential drug for treating proliferative glomerular diseases related to obesity and lipid disorders.

Relationships of arterial hypertension and reduced renal function in a population 25-45 years

AIM

To study relationships of reduced renal function with hypertension and other cardiometabolic risk factors in persons aged 25-45 years.

MATERIALS AND METHODS

A cross-sectional population study of one of the typical district of Novosibirsk (Russia) was performed during 2013-2016 years. The study included 468 men and 606 women aged 25-45 years. Blood pressure (BP), waist circumference (WC), blood lipids, glucose, creatinine were measured. Glomerular filtration rate (GFR) was calculated with the formula CKD-EPI. Hypertension was registered if blood pressure (BP) was ≥140/90 mm Hg, reduced kidney function - at GFR&lt;90 ml/min/1.73 cm2.

RESULTS

Prevalence of hypertension among men was 28%, among women - 9%. The proportion of people with GFR&lt;90 ml/min/1.73 cm2 among men was 9.8%, among women - 34%. Among all examined people GFRs &lt;60 ml/min/1.73 cm2 was revealed in 0.3% only. The association of hypertension with reduced renal function was determined only in men. Based on results of multivariate linear regression analysis, a significant negative association of GFR with age was determined, there was no association of GFR with systolic BP (SBP) in either men or women. In men, inverse relationships of GFR with low-density lipoprotein cholesterol (LDL-С), triglycerides (TG), direct - with WC were determined. Significant inverse association of GFR with diastolic BP (DBP) was revealed only after exception of TG from the regression model. In women, GFR's inverse relationship with LDL-С and DBP was observed, and the direct - with WC. In stepwise analysis the validity of all associations was confirmed after exception of the association of GFR with WC in men.

CONCLUSION

In a population of 25-45 years a reduced GFR was associated with increased DBP; levels of LDL-С, TG showed negative association with GFR; in men increased TG levels were more important in reducing GFR than elevated DBP.

Medical therapy of stricturing Crohn's disease: what the gut can learn from other organs - a systematic review

Crohn’s disease (CD) is a chronic remitting and relapsing disease. Fibrostenosing complications such as intestinal strictures, stenosis and ultimately obstruction are some of its most common long-term complications. Despite recent advances in the pathophysiological understanding of CD and a significant improvement of anti-inflammatory therapeutics, medical therapy for stricturing CD is still inadequate. No specific anti-fibrotic therapy exists and the incidence rate of strictures has essentially remained unchanged. Therefore, the current therapy of established fibrotic strictures comprises mainly endoscopic dilation as well as surgical approaches. However, these treatment options are associated with major complications as well as high recurrence rates. Thus, a specific anti-fibrotic therapy for CD is urgently needed. Importantly, there is now a growing body of evidence for prevention as well as effective medical treatment of fibrotic diseases of other organs such as the skin, lung, kidney and liver. In face of the similarity of molecular mechanisms of fibrogenesis across these organs, translation of therapeutic approaches from other fibrotic diseases to the intestine appears to be a promising treatment strategy. In particular transforming growth factor beta (TGF-β) neutralization, selective tyrosine kinase inhibitors, blockade of components of the renin-angiotensin system, IL-13 inhibitors and mammalian target of rapamycin (mTOR) inhibitors have emerged as potential drug candidates for anti-fibrotic therapy and may retard progression or even reverse established intestinal fibrosis. However, major challenges have to be overcome in the translation of novel anti-fibrotics into intestinal fibrosis therapy, such as the development of appropriate biomarkers that predict the development and accurately monitor therapeutic responses. Future clinical studies are a prerequisite to evaluate the optimal timing for anti-fibrotic treatment approaches, to elucidate the best routes of application, and to evaluate the potential of drug candidates to reach the ultimate goal: the prevention or reversal of established fibrosis and strictures in CD patients.

Downregulation of p38 MAPK involved in inhibition of LDL-induced proliferation of mesangial cells and matrix by curcumin

Curcumin, as a main pharmacological component in the traditional Chinese medicine-turmeric, has shown anti-inflammatory, anti-oxidation, anti-tumor and anti-fibrotic effects. This study aimed to investigate the possible underlying signaling pathway which was involved in the inhibition of LDL-induced proliferation of mesangial cells and matrix by curcumin. Rat mesangial cells in vitro were incubated with low-density lipoprotein (LDL) and different concentrations of curcumin (0, 6.25, 12.5, 25.0 μmol/L) or p38 MAPK inhibitor, SB203580 (10 μmol/L). Under LDL incubation, mesangial cells proliferated, the expression of MMP-2 mRNA and protein was decreased, the expression of COX-2 mRNA and protein was increased, reactive oxygen species (ROS) generation was increased and p38 MAPK was activated significantly (P<0.05). When LDL-induced cells were treated with curcumin in the concentration of 12.5 or 25.0 μmol/L, LDL-induced proliferation of mesangial cells was suppressed, the expression of MMP-2 mRNA and protein increased, the expression of COX-2 mRNA and protein downregulated, the production of ROS inhibited and p38 MAPK inactivated (P<0.05). In conclusion, curcumin can inhibit the LDL-induced proliferation of mesangial cells and up-regulate the expression of MMP-2, which may be related with the inhibitory effect of curcumin on COX-2 expression, ROS production and p38 MAPK.

Dyslipoproteinemia and impairment of renal function in diabetic kidney disease: an analysis of animal studies, observational studies, and clinical trials

Dyslipoproteinemia is highly prevalent in diabetes, chronic kidney disease, and diabetic kidney disease (DKD). Both diabetes and chronic kidney disease (CKD) are associated with hypertriglyceridemia, lower high-density lipoprotein, and higher small, dense low-density lipoprotein. A number of observational studies have reported that dyslipidemia may be associated with albuminuria, renal function impairment, and end-stage renal disease (ESRD) in the general population, and especially in CKD and DKD patients. Diabetic glomerulopathy and the related albuminuria are the main manifestations of DKD. Numerous animal studies support the finding that glomerular atherosclerosis is the main mechanism of glomerulosclerosis in CKD and DKD. Some randomized, controlled trials suggest the use of statins for the prevention of albuminuria and renal function impairment in CKD and DKD patients. However, a large clinical study, the Study of Heart and Renal Protection (SHARP), does not support that statins could reduce ESRD in CKD. In this article, we analyze the complex association of dyslipoproteinemia with DKD and deduce its relevance from animal studies, observational studies, and clinical trials. We show that special subgroups could benefit from the statin treatment.

Association of dyslipidemia with renal outcomes in chronic kidney disease

Dyslipidemia is highly prevalent in patients with chronic kidney disease (CKD) and the relationship between dyslipidemia with renal outcomes in patients with moderate to advanced CKD remains controversial. Hence, our objective is to determine whether dyslipidemia is independently associated with rapid renal progression and progression to renal replacement therapy (RRT) in CKD patients. The study analyzed the association between lipid profile, RRT, and rapid renal progression (estimated glomerular filtration rate [eGFR] slope <-6 ml/min/1.73 m(2)/yr) in 3303 patients with stages 3 to 5 CKD. During a median 2.8-year follow-up, 1080 (32.3%) participants commenced RRT and 841 (25.5%) had rapid renal progression. In the adjusted models, the lowest quintile (hazard ratios [HR], 1.23; 95% confidence interval [CI], 1.01 to 1.49) and the highest two quintiles of total cholesterol (HR, 1.25; 95% CI, 1.02 to 1.52 and HR, 1.35; 95% CI, 1.11 to 1.65 respectively) increased risks for RRT (vs. quintile 2). Besides, the highest quintile of total cholesterol was independently associated with rapid renal progression (odds ratio, 1.36; 95% CI, 1.01 to 1.83). Our study demonstrated that certain levels of dyslipidemia were independently associated with RRT and rapid renal progression in CKD stage 3-5. Assessment of lipid profile may help identify high risk groups with adverse renal outcomes.

Renal safety of intensive cholesterol-lowering treatment with rosuvastatin: a retrospective analysis of renal adverse events among 40,600 participants in the rosuvastatin clinical development program

OBJECTIVE

Intensive lowering of low-density lipoprotein cholesterol (LDL-C) with statins reduces cardiovascular risk but can cause liver-, muscle-, and possibly renal-related adverse events (AEs). We assessed the effects of rosuvastatin on the risk of developing renal impairment or renal failure among participants in the rosuvastatin clinical development program.

METHODS

The analysis was based on AE data reported by investigators from 36 studies that included 40,600 participants who did not have advanced, pre-existing renal disease. Rates of renal AEs were determined based on time to first occurrence of renal impairment or renal failure.

RESULTS

Renal impairment or renal failure was reported in 536 study participants during 72,488 patient-years of follow-up. Renal event rates were higher in patients with history of heart failure (n = 5011), hypertension (n = 21,864), diabetes (n = 5165), or estimated glomerular filtration rate (eGFR) <60 ml/min/1.73 m(2) (n = 9507) at baseline but did not differ with rosuvastatin compared with placebo or with rosuvastatin 40 mg compared with rosuvastatin 10mg. Relative risk (RR) estimates obtained from pooled analysis of placebo-controlled trials were RR: 1.03 (95% CI: 0.86-1.23, p = 0.777) for any reported renal impairment or renal failure event, RR: 1.02 (95% CI: 0.76-1.37, p = 0.894) for serious renal AEs, and RR: 0.70 (95% CI: 0.36-1.35, p = 0.282) for renal AEs leading to death.

CONCLUSION

These findings suggest that intensive LDL-C-lowering treatment with rosuvastatin does not affect the risk of developing renal insufficiency or renal failure in patients who do not have advanced, pre-existing renal disease.

Nephroprotective and clinical potential of statins in dialyzed patients

BACKGROUND

The combination of increased cardiovascular mortality and vascular complications due to dyslipidaemia in chronic kidney disease (CKD) has focused attention onto the potential beneficial effects of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMG-CoA) inhibitors (statins) on the course of CKD.

OBJECTIVE

To examine the use of statins in CKD.

METHODS

A review of relevant literature.

RESULTS/CONCLUSION

Current evidence from clinical trials in CKD patients on maintenance dialysis is limited. Therefore, the routine use of statins in this population remains the decision of individual physicians in discussion with their patients.

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

Dyslipidemia and the contributions of oxidized low-density lipoproteins (ox-LDL) are independent cardiovascular risk factors. There is growing evidence that dyslipidemia contributes not only to cardiovascular disease but also to the progressive decline of renal function in diabetic and non-diabetic kidney disease. Ox-LDL, by generating inflammation and oxidative stress, contributes to a pro-atherogenic mileu and leads to endothelial dysfunction, subsequent glomerular filtration barrier damage, and progressive renal injury. Chronic kidney disease (CKD), in turn, induces deleterious effects on lipid metabolism. Therefore, by inhibiting cholesterol synthesis and reducing ox-LDL, HMG CoA reductase inhibitors (statins) are attractive therapeutic options to preserve renal function. Current evidence demonstrates a reduction in cardiovascular risk and improved renal outcomes especially in patients with mild to moderate impairment of renal function. Evidence supports a beneficial role of statins thought to extend beyond their lipid-lowering effect, referred to as pleiotropic actions. These actions include modulatory effects on inflammation, oxidative stress and thrombosis, derived from their ability to prevent the formation of isoprenoid intermediates involved in cellular signaling, posttranslational modification of proteins and cellular function. This translates to potential reductions in the rate of decline in GFR in CKD and adverse effects of type 2 diabetes mellitus in the kidney. This review examines the role of statins for reno-protection as well as cardiovascular benefit in patients with CKD.

Chronic kidney disease as a cardiovascular risk state and considerations for the use of statins

Chronic kidney disease (CKD) creates one of the highest risk atherosclerotic states that can occur in human beings. The use of 3-hydroxy-3-methylglutaryl coenzyme reductase inhibitors (statins) has gained widespread acceptance in the general population for the purposes of lowering low-density lipoprotein cholesterol (LDL-C) and reducing the future risks of myocardial infarction, stroke, and cardiac death. In patients with CKD, the balance of benefits and risks of statins appears to be different than that in the general population. Reductions in LDL-C with statins may be associated with a reduced progression of CKD. Importantly, recent studies suggest statins are associated with a reduction in rates of acute kidney injury, mediated by ischemic insults and oxidative stress, after cardiac surgery and exposure to iodinated contrast. A reduction in cardiovascular events with LDL-C reduction in CKD and dialysis patients is yet to be proven. In addition, studies suggest that there are higher adverse drug effects with statins in CKD. This work will address the benefits and risks of this important treatment option for the growing population of patients with CKD, who have not undergone renal transplantation, and are at very high risk of cardiovascular events.

Multiorgan-protective actions of blockers of the renin-angiotensin system, statins and erythropoietin: common pleiotropic effects in reno-, cardio- and neuroprotection

Renal diseases induce nephroprotective measures that may affect the heart, brain and other organs. In addition, many cardiovascular and neurological diseases are accompanied by renal lesions. For these reasons, multiorgan-protective measures, including cardio-, reno- and neuro-protective measures, are necessary to treat these diseases. The drugs used in nephrology are often pleiotropic. Although they usually address a single organ or tissue, many of them have complex actions that may provide multiorgan-protection. The present paper aims to review 3 classes of drugs that are commonly prescribed in nephrological practice: statins, RAS blockers (such as ACEIs and ARBs) and erythropoietin (EPO). This paper highlights the renoprotective actions, as well as those that are protective of the heart, brain and other organs, of these drugs at the cellular and molecular level. Their protective actions are attributable to their main effects and pleiotropic effects. The protective pleiotropic actions of these drugs may be exerted on multiple organs, making them multiorgan-protective. Another objective is to analyse the shared multiorgan-protective pleiotropic effects of RAS blockers (ACEIs and ARBs), statins and erythropoietin. This will allow for the practical association of the main renoprotective drugs with multiorgan protection.

Targeting of RhoA/ROCK signaling ameliorates progression of diabetic nephropathy independent of glucose control

OBJECTIVE

RhoA, a small GTPase protein, and its immediate downstream target, Rho kinase (ROCK), control a wide variety of signal transduction pathways. Recent studies have shown that fasudil, a selective ROCK inhibitor, may play a pivotal role in a number of pathological conditions, ranging from cardiovascular diseases to pulmonary hypertension and erectile dysfunction. Considerable evidence suggests that some of the beneficial effects of statins may also stem from their modulatory effects on RhoA/ROCK signaling. In the current study, we hypothesized that pharmacological blockade of the RhoA/ROCK pathway with either fasudil or simvastatin would ameliorate progression of diabetic nephropathy.

RESEARCH DESIGN AND METHODS

In two separate experiments, diabetic db/db mice received fasudil (10 mg x kg(-) x day(-) i.p.) or simvastatin (40 mg x kg(-) x day(-) p.o.) for 16 weeks. Untreated db/db and db/m mice served as controls.

RESULTS

The kidney cortices of untreated db/db mice displayed increased ROCK activity compared with db/m mice. The fasudil-treated mice exhibited a significant reduction in ROCK activity, albuminuria, glomerular collagen IV accumulation, and urinary collagen IV excretion compared with untreated db/db mice. Interestingly, blood glucose was unaffected by fasudil administration. Treatment with simvastatin significantly attenuated RhoA activation in the kidney cortices of db/db mice and resulted in a significant reduction of albuminuria and mesangial matrix expansion.

CONCLUSIONS

Based on these results, we propose that RhoA/ROCK blockade constitutes a novel approach to the treatment of diabetic nephropathy. Our data also suggest a critical role for RhoA/ROCK activation in the pathogenesis of diabetic nephropathy.

Protective effects of atorvastatin on chronic allograft nephropathy in rats

OBJECTIVE

Chronic allograft nephropathy (CAN) is the leading cause of late kidney allograft loss. Recent studies have suggested that atorvastatin (ATO) may interact with the acute inflammatory process in the renal interstitium and suppress the proliferation of mesangial cells. We hypothesized that ATO could also inhibit the chronic inflammatory process and prevent the progression of CAN.

MATERIALS AND METHODS

Fisher (F344) kidneys were orthotopically transplanted into Lewis rat recipients. Lewis-to-Lewis rat kidney transplantation was served as the syngeneic control (Syn group). Allograft recipients were randomized and treated with cyclosporine A alone (Allo group) or in combination with ATO (15 or 30 mg/kg/d intrgastric, respectively, the low dose treatment group/high dose treatment group [LT/HT] groups). Renal function and the urine protein excretion were analyzed. Animals were sacrificed 20 weeks posttransplantation for histological and immunohistochemical studies, as well as analysis of mRNA levels of cytokines and chemokines.

RESULTS

Renal function progressively deteriorated and substantial proteinuria developed in the Allo group compared with the Syn group. ATO-treated rats had significantly higher creatinine clearance rate and less amount of proteinuria. Histological examination revealed obvious features of CAN in the Allo group, whereas LT/HT groups demonstrated minimal glomerulosclerosis, interstitial fibrosis, intimal thickening, and tubular atrophy. The numbers of infiltrating mononuclear cells (ED1+, CD8+, and CD68+) decreased markedly, and the intragraft expression of transforming growth factor beta1 (TGF-beta1) and collagen III were also significantly attenuated in the LT/HT groups, as compared with the Allo group. The mRNA levels of proinflammatory cytokines (interleukin-2, interferon-gamma, interleukin-10), chemokines (RANTES, MCP-1), and profibrotic genes (TGF-beta1, collagen III) were significantly down-regulated in ATO-treated rats.

CONCLUSION

Atorvastatin showed excellent favorable effects on blocking renal inflammation and fibrosis, and thus, efficiently inhibited the development and progression of CAN, which might improve the long-term survival rate of renal allografts.

HMG-CoA reductase inhibitors and the kidney

During the last two decades, numerous studies have demonstrated that 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) diminish the risk of cardiovascular morbidity and mortality. Although these studies have focused primarily on the ability of statins to lower circulating levels of low-density lipoprotein cholesterol, more recent research has shown that statins may protect the vasculature via pleiotropic effects not directly related to lipid lowering. These include adjustments in cell-signaling pathways that play a role in atherogenesis and that affect the expression of inflammatory elements, curtail oxidative stress, and enhance endothelial function. More recently, researchers have begun to explore whether these agents exert similar beneficial effects in renal parenchymal and renovascular disease. This review examines the available evidence that dyslipidemia may augment the inflammatory reaction of cytokines in patients with renal disease and that statins may improve renal dysfunction by altering the response of the kidney to dyslipidemia, even in persons with end-stage renal disease on dialysis or with renal transplantation. In this context, some data suggest that statin-mediated alterations in inflammatory responses and endothelial function may reduce proteinuria and the rate of progression of kidney disease.

Effects of endothelin-1 on thymidine uptake and fibronectin production of diabetic glomeruli

AIM

Endothelin-1 (ET-1) is a potent mitogenic and vasoconstricting agent. The effect of ET-1 upon the diabetic kidney may be important because diabetic glomeruli exhibit a poor contractile response and because diabetic kidneys do not contract even by end-stage renal failure.

METHODS

In the present study, we investigated the effect of ET-1 on diabetic glomeruli that were freshly isolated from Wistar rats after streptozotocin-induced diabetes for 1 week (DM1W), 1 month (DM1M) and 3 months (DM3M), respectively, and then observed the glomerular uptake of [(3)H]-labelled thymidine and the production of fibronectin.

RESULTS

We found that the basal [(3)H]-labelled thymidine uptake of isolated glomeruli was significantly higher in DM1M and DM3M than in the normal control (both P < 0.05). ET-1 enhanced the [(3)H]-labelled thymidine uptake in both normal and DM1W glomeruli (both P < 0.005), but not in DM1M and DM3M, and all were not suppressed by exogenous medications. The basal production of fibronectin in isolated glomeruli was also significantly higher in DM1M and DM3M than in the normal controls (P < 0.05 and P < 0.005, respectively). ET-1 enhanced the fibronectin production in both normal and all diabetic groups. Pretreatment with insulin and dexamethasone suppressed the ET-1-enhanced fibronectin production in diabetic but not in normal glomeruli, while indomethacin and heparin had no effect in all groups.

CONCLUSION

Our results indicated that basal glomerular thymidine uptake and fibronectin production were enhanced in diabetic rats, and that ET-1 further enhanced the cellular proliferation and fibronectin production of isolated diabetic glomeruli. The ET-1-enhanced fibronectin production can be partially attenuated by insulin and dexamethasone.

Glycoprotein Changes in Non-Insulin Dependent Diabetic Rats: Effect of N-Benzoyl-D-Phenylalanine and Metformin

The effect of N-benzoyl-D-phenylalanine (NBDP) and metformin on neonatal streptozotocin (nSTZ) induced diabetes has been studied on plasma and tissue glycoproteins. In some pathological conditions, such as cancer, rheumatoid arthritis and diabetes, there is an abnormal glycosylation of acute phase serum proteins. As most serum proteins are produced in the liver, we have examined glycoprotein metabolism in diabetic condition. To induce non-insulin-dependent diabetes mellitus (NIDDM) a single dose of streptozotocin (100 mg/kg body weight) was injected into two day old rats. After 10-12 weeks, rats weighing above 150 g were selected for NIDDM model. In these rat, blood glucose and plasma glycoproteins were significantly increased whereas plasma insulin was significantly decreased. There was a significant decrease in the level of sialic acid and elevated levels of hexose, hexosamine and fucose in tissues. Oral administration of NBDP and metformin to diabetic rats decreased blood glucose and plasma glycoproteins. Plasma insulin and tissue sialic acid were increased whereas tissue concentrations of hexose, hexosamine and fucose were near normal. Our study suggests that NBDP and metformin possess a significant beneficial effect on glycoproteins in addition to their antidiabetic effect.

Pleiotropic effects of 3-hydroxy-3-methylglutaryl coenzyme a reductase inhibitors on renal function

Pleiotropic, or non-lipid-dependent, effects mediated by 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins) have important clinical implications for the cardiovascular (CV) system. Atherosclerosis is an inflammatory process accompanied by increases in levels of plasma inflammatory markers and accumulation of immune cells within atherosclerotic plaques. Statins not only decrease serum lipid levels, but also inhibit signaling molecules at several points in inflammatory pathways. The anti-inflammatory effects and improved endothelial function associated with statin therapy are thought to be partly responsible for the reduction in CV morbidity and mortality. In analogy, patients with chronic kidney disease administered statins for CV risk reduction show evidence of improved renal function. However, whether statins confer similar protective benefits on the kidney has not been established. Several lines of evidence suggest that similar etiologic and pathological processes may be involved in CV and chronic kidney diseases. If inflammation and functional changes in the renovascular endothelium contribute to the progression of kidney disease, statins are likely to be effective in the treatment of renal disease. In this review, we critically consider emerging data indicating that statins may modulate renal function by altering the inflammatory response of the kidney and renal vasculature to dyslipidemia. Whether the amelioration of renal function by statins is separable from the lipid-lowering effects of these drugs still remains to be delineated. Other questions that remain to be addressed and issues that should be investigated also are presented.

HMG-CoA reductase inhibitors and the kidney

HMG-CoA (3-hydroxy-3-methylglutaryl-CoA) reductase inhibitors (statins) have been shown to reduce serum cholesterol and cardiovascular morbidity and mortality. The mechanisms of these beneficial effects are reviewed. Altered inflammatory responses and improved endothelial function mediated by statins are thought to be, in part, responsible for the reduction in cardiovascular events. It has not been well established whether statins confer similar benefits to the kidney. In this review, we critically consider the available data whereby dyslipidemia mediates renal dysfunction by modulating the inflammatory response to diverse cytokines. We also review the emerging database suggesting that statins may modulate renal dysfunction by altering the response of the kidney to dyslipidemia, particularly in patients with end-stage renal disease (ESRD) and post-kidney transplant.

Are 3-Hydroxy-3-Methylglutaryl-CoA Reductase Inhibitors Renoprotective?: Table 1

Statins reduce serum cholesterol and cardiovascular morbidity and mortality. The mechanisms for these beneficial effects are reviewed. Altered inflammatory responses and improved endothelial function mediated by statins are thought to be partly responsible for the reduction of morbidity and mortality as a result of cardiovascular events. In analogy, whether statins confer similar benefits on the kidney has not been established. This review critically considers the available data whereby dyslipidemia mediates renal dysfunction by modulating the inflammatory response to diverse cytokines. Also reviewed is the emerging database indicating that statins may modulate renal function by altering the response of the kidney to dyslipidemia.

Role of lipid control in diabetic nephropathy

Patients with diabetic nephropathy are known to be associated with many lipoprotein abnormalities, including higher plasma levels of very low-density lipoprotein, low-density lipoprotein and triglycerides, and lower levels of high-density lipoprotein. Many studies have reported that lipids may induce both glomerular and tubulointerstitial injury through mediators such as cytokines, reactive oxygen species, chemokines, and through hemodynamic changes. Clinical studies in patients with diabetic nephropathy showed that lipid control can be associated with an additional effect of reduction in proteinuria. Experimental studies demonstrated that lipid-lowering agents exerted a certain degree of renoprotection, through both indirect effects from lipid lowering and a direct effect on cell protection. Therefore, lipid control appears to be important in the prevention and treatment of diabetic nephropathy. Diabetic nephropathy has become the leading cause of end-stage renal failure in many countries, including Taiwan. One of the major risk factors for the development and progression of diabetic nephropathy is dyslipidemia. In this paper we will review the role of lipid in mediating renal injury and the beneficial effects of lipid control in diabetic nephropathy.

Chemopreventive effect of five drugs on renal interstitial fibrosis induced by an aristolochic acid-containing Chinese herb in rats

BACKGROUND/AIMS

This study focuses on the chemopreventive effect of five drugs on renal interstitial fibrosis induced by an aristolochic acid-containing Chinese herb Mu-Tong.

METHODS

Renal interstitial fibrosis was induced in rats by administration of the Mu-Tong solution intragastrically for 6 weeks, and 36 rats were randomly divided into six groups: (1) Mu-Tong, (2) Mu-Tong + captopril, (3) Mu-Tong + losartan, (4) Mu-Tong + simvastatin, (5) Mu-Tong + spironolactone, and (6) Mu-Tong + diammonium glycyrrhizinate. Blood biochemistry and extracellular matrix were detected at weeks 0, 2, 4, and 6. At the end of week 6, kidney tissue of all groups was evaluated with special Masson staining for the degree of renal fibrosis as well as regular histopathology.

RESULTS

Mu-Tong caused progressive elevation of blood urea nitrogen, creatinine, hyaluronic acid, procollagen type III, and laminin. All five drugs suppressed elevation of blood biochemistry and extracellular matrix to some degree, but only the simvastatin group showed a significantly reduced percentage of positive Masson staining area in renal section compared to the Mu-Tong group (p < 0.05).

CONCLUSIONS

Our study indicates that Mu-Tong induces a similar kidney injury with general characteristics in patients with renal interstitial fibrosis. All five different drugs have suppressive effects on Mu-Tong-induced renal function damage, and in particular, simvastatin shows a protective effect on development of Mu-Tong-induced renal interstitial fibrosis to a certain degree.

Effect of Pravastatin on Low-Density Lipoprotein Oxidation and Myocardial Perfusion in Young Adults With Type 1 Diabetes

OBJECTIVE

Diabetes has been associated with increased oxidative stress and impaired vascular function. Statins have been shown to reduce low-density lipoprotein (LDL) oxidizability and improve myocardial perfusion in hypercholesterolemic nondiabetic subjects. We studied whether pravastatin decreases LDL oxidation and improves myocardial perfusion in normocholesterolemic subjects with type 1 diabetes.

METHODS AND RESULTS

In this randomized, double-blind study, myocardial perfusion was measured at rest and during dipyridamole stimulation with positron emission tomography and [15O]H2O during hyperinsulinemic euglycemia in 42 patients (age 30+/-6 years; LDL cholesterol 2.48+/-0.57 mmol/L) before and after 4-month treatment with pravastatin 40 mg/d or placebo. In addition, 12 healthy nondiabetic subjects were studied. LDL oxidation was measured by determining the level of baseline diene conjugation in lipids extracted from LDL. The level of LDL oxidation was similar in the pravastatin and placebo groups before treatment (23.9+/-4.6 versus 25.6+/-9.5 micromol/L, respectively) and decreased significantly during pravastatin treatment to 19.5+/-5.0 micromol/L (P<0.005). Myocardial perfusion reserve was significantly lower in diabetic patients compared with controls (4.15+/-1.29 versus 5.31+/-1.86, P<0.05) and did not change after treatment. Glycemic control and insulin sensitivity remained unchanged during treatment.

CONCLUSIONS

Pravastatin treatment, resulting in decreased LDL oxidation, did not improve myocardial perfusion reserve in subjects with type 1 diabetes.

The leaf extract of Ginkgo Biloba L. suppresses oxidized LDL-stimulated fibronectin production through an antioxidant action in rat mesangial cells

1 The leaf extract of Ginkgo Biloba L. exhibits a variety of pharmacological effects through an antioxidant action. We examined the effects of the leaf extract (Ginkgolon-24) on the production of fibronectin induced by oxidized low-density lipoprotein (oxLDL) in rat mesangial cells. 2 Stimulation with oxLDL accelerated the production of fibronectin with the preceding generation of reactive oxygen species (ROS). Pretreatment with Ginkgolon-24 inhibited the oxLDL-induced fibronectin production as well as ROS generation. 3 oxLDL also elicited the activation of SP-1, nuclear factor-kappaB, and cAMP response element-binding protein, which are transcription factors involved in the fibronectin production. Among these activated transcription factors, Ginkgolon-24 inhibited the activation of SP-1 only. 4 Furthermore, 7-ketocholesterol, an oxidized lipid in oxLDL particles, induced the production of fibronectin and the activation of SP-1, which were also suppressed by Ginkgolon-24. 5 These results suggest that the leaf extract of Ginkgo Biloba L. inhibits the oxLDL-induced production of fibronectin probably through inhibitory effects on ROS generation and SP-1 activation in rat mesangial cells.

Pravastatin treatment attenuates interstitial inflammation and fibrosis in a rat model of chronic cyclosporine-induced nephropathy

We investigated the effects of pravastatin, a competitive inhibitor of 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, on interstitial inflammation and fibrosis, using an animal model of chronic cyclosporine A (CsA)-induced nephropathy. Sprague-Dawley rats were maintained on a low-salt diet (0.05% sodium) and treated daily for 1 or 4 wk with vehicle (olive oil; 1 ml/kg sc), CsA (15 mg/kg sc), or both CsA and pravastatin (5 or 20 mg/kg in the drinking water). Anti-inflammatory and antifibrotic effects of pravastatin were studied by evaluating the concentrations of the inflammatory mediators osteopontin (OPN) and C-reactive protein (CRP), of fibrotic cytokine-transforming growth factor (TGF)-β1, and the presence of ED-1-positive cells (macrophages). In addition, renal function, serum lipid levels, histopathology (arteriolopathy and tubulointerstitial fibrosis), and the expression of the vasoactive factors endothelial nitric oxide synthase (eNOS) and renin protein were also compared for different treatment groups. Pravastatin induced dose-dependent decreases in the expression of OPN, intrarenal CRP, and TGF-β1, and in the numbers of ED-1-positive cells at 1 and 4 wk. These were accompanied by a significant attenuation of tubulointerstitial fibrosis at 4 wk. The downregulation of eNOS protein expression in CsA-treated rat kidney was markedly upregulated by pravastatin treatment, although intrarenal renin expression was unaffected. Renal dysfunction induced by CsA significantly improved with administration of pravastatin at a dose of 20 mg/kg. Neither CsA nor pravastatin influenced serum lipid or high-sensitivity CRP levels in the treatment groups. Thus in chronic CsA nephropathy, pravastatin effectively abrogates the progression of tubulointerstitial inflammation and fibrosis. This may support the clinical use of pravastatin.

Involvement of reactive oxygen species and SP-1 in fibronectin production by oxidized LDL

We examined the mechanisms responsible for the production of fibronectin induced by oxidized low-density lipoprotein (oxLDL) in rat mesangial cells. oxLDL accelerated the production of fibronectin with the preceding generation of reactive oxygen species (ROS). Pretreatment with N-acetylcysteine suppressed the oxLDL-induced fibronectin production as well as ROS generation. oxLDL also elicited the activation of SP-1, nuclear factor-kappaB, and cAMP response element-binding protein, but not activator protein-1. Among these activated transcription factors, N-acetylcysteine inhibited the activation of SP-1 only. 7-Ketocholesterol, an oxidized lipid in oxLDL particles, induced the production of fibronectin and the activation of SP-1, those which were suppressed by N-acetylcysteine. Furthermore, mithramycin A, an inhibitor of SP-1, also suppressed the oxLDL- and 7-ketocholesterol-stimulated production of fibronectin. These results suggest that oxLDL stimulates fibronectin production, at least in part, through the ROS-dependent activation of SP-1 in rat mesangial cells, and further that the ROS-dependent cellular responses may be elicited by 7-ketocholesterol.