Direct inhibitory effects of simvastatin on matrix accumulation in cultured murine mesangial cells

Improved anti-fibrotic effects by combined treatments of simvastatin and NS-398 in experimental liver fibrosis models

BACKGROUND/AIMS

Efficient anti-fibrotic therapies are required for the treatment of liver cirrhosis. Hydroxymethylglutaryl-coenzyme A reductase inhibitors (statins) and cyclooxygenase-2 (COX-2) inhibitors have been reported to have anti-fibrotic effects. Here, we investigated whether combined treatment with a statin and a COX-2 inhibitor has synergistic anti-fibrotic effects.

METHODS

The effects of treatment strategies incorporating both simvastatin and a COX-2 inhibitor, NS-398, were investigated using an immortalized human hepatic stellate cell line (LX-2) and a hepatic fibrosis mouse model developed using thioacetamide (TAA) in drinking water. Cellular proliferation was investigated via 5-bromo-2-deoxyuridine uptake. Pro- and anti-apoptotic factors were investigated through Western blotting and real-time polymerase chain reaction analysis.

RESULTS

The evaluation of the anti-proliferative effects on LX-2 cells showed that the observed effects were more pronounced with combination therapy than with single-drug therapy. Moreover, hepatic fibrosis and collagen deposition decreased significantly in TAA-treated mice in response to the combined treatment strategy. The mechanisms underlying the anti-fibrotic effects of the combination therapy were investigated. The effects of the combination therapy were correlated with increased expression levels of extracellular signal-regulated kinase 1/2 signaling molecules, upregulation of the Bax/Bcl-2 signaling pathway, inhibition of the transforming growth factor-β signaling pathway, and inhibition of tissue inhibitor of matrix metalloproteinases 1 and 2.

CONCLUSION

The combination of simvastatin and NS-398 resulted in a synergistic anti-fibrotic effect through multiple pathways. These findings offer a theoretical insight into the possible clinical application of this strategy for the treatment of advanced liver diseases with hepatic fibrosis.

Atorvastatin Improves Peritoneal Sclerosis Induced by Hypertonic PD Solution in Rats

Background

Peritoneal sclerosis is a complication of peritoneal dialysis and results in ultrafiltration failure. It is related to chronic peritoneal injury due to dialysis solution content and recurrent peritonitis. Statins have anti-inflammatory properties which may be of value in modulating responses to injury. We evaluated the capacity of atorvastatin to modify peritoneal alterations secondary to hypertonic glucose.

Methods

Thirty-two non-uremic rats were divided into three groups: group I (Sham) rats received no treatment (n=11), group II received hypertonic (3.86%, 10 ml/day) PD solution (n=10) and group III received hypertonic PD solution (10 ml/day) plus 80 mg/L atorvastatin in drinking water (n=11). After four weeks, a one-hour peritoneal equilibration test (PET) was performed with 3.86% PD solution. Dialysate-to-plasma urea ratio (D/P urea), glucose reabsorption (D1/D0 glucose), ultrafiltration volume (UF), dialysate protein, TGF-ß1 and VEGF levels were determined.

Results

Administration of atorvastatin resulted in preserved UF (4.9±0.8 vs 7.5±0.6 mL, p <0.01), protein loss (2.2±0.2 vs 2.1±0.1 g/L, p >0.05), and peritoneal thickness (53±3 vs 26±4 μm, p <0.01). D1/D0 glucose was significantly reduced in the dextrose group (0.70±0.02 vs 0.56±0.04, p <0.01). Both higher levels of TGF-ß1 (206±40 vs 474±120 pg/mL, p<0.05), and VEGF in dialysate effluent (4±0.4 vs 7.9±3 pg/mL, p>0.05), was determined in the dextrose group.

Conclusion

Exposure to hypertonic glucose solution resulted in alterations in peritoneal transport manifested by a rapid dissipation of the glucose gradient and resultant impaired UF response. Administration of atorvastatin led to prevention of these alterations. We suggest that the anti-inflammatory properties of statins are useful in providing protection of the peritoneal membrane from the effects of hypertonic glucose.

Statin pretreatment inhibits the lipopolysaccharide-induced epithelial-mesenchymal transition via the downregulation of toll-like receptor 4 and nuclear factor-κB in human biliary epithelial cells

BACKGROUND AND AIM

Epithelial-mesenchymal transition (EMT) of biliary epithelial cells (BECs) plays an important role in biliary fibrosis. This study investigated the effects of simvastatin on the lipopolysaccharide (LPS)-induced EMT and related signal pathways in BECs.

METHODS

Biliary epithelial cells were exposed to LPS (2 µg/mL) or transforming growth factor β1 (TGF-β1) (5 ng/mL) for 5 days. The EMT was assessed by a gain of mesenchymal cell markers (vimentin, N-cadherin, slug, and Twist-1) and a loss of epithelial cell markers (E-cadherin). The effects of simvastatin on the EMT induced by LPS or TGF-β1 were determined by the changes in the levels of EMT markers and TLR4 and in the c-Jun N-terminal kinase (JNK), p38, and nuclear factor-κB (NF-κB) signaling pathways.

RESULTS

Compared with the BECs treated with LPS alone, co-treatment with simvastatin and LPS induced an increase in the expression of E-cadherin and decreases in the expression levels of mesenchymal cell markers. The LPS-induced TLR4 expression level was slightly decreased by co-treatment with simvastatin. LPS-induced BEC growth was markedly inhibited by co-treatment with simvastatin. Furthermore, pretreatment with simvastatin inhibited the LPS-induced EMT in BECs by downregulating NF-κB and JNK phosphorylation. The suppressive effects of simvastatin pretreatment on the induction of the EMT by TGF-β1 were also demonstrated in H69 cells.

CONCLUSIONS

Our results demonstrate that LPS or TGF-β1 promote the EMT in BECs that that pretreatment with simvastatin inhibited the induced EMT by downregulating toll-like receptor 4 and NF-κB phosphorylation. This finding suggests that simvastatin can be considered a new agent for preventing biliary fibrosis associated with the EMT of BECs.

Atorvastatin and rosuvastatin do not prevent thioacetamide induced liver cirrhosis in rats

AIM: To examine whether the administration of atorvastatin and rosuvastatin would prevent experimentally-induced hepatic cirrhosis in rats.

METHODS: Liver cirrhosis was induced by injections of thioacetamide (TAA). Rats were treated concurrently with TAA alone or TAA and either atorvastatin (1,10 and 20 mg/kg) or rosuvastatin (1, 2.5, 5, 10 and 20 mg/kg) given daily by nasogastric gavage.

RESULTS: Liver fibrosis and hepatic hydroxyproline content, in the TAA-treated group was significantly higher than those of the controls [11.5 ± 3.2 vs 2.6 ± 0.6 mg/g protein (P = 0.02)]. There were no differences in serum aminotransferase levels in the TAA controls compared to all the groups treated concomitantly by statins. Both statins used in our study did not prevent liver fibrosis or reduce portal hypertension, and had no effect on hepatic oxidative stress. Accordingly, the hepatic level of malondialdehyde was not lower in those groups treated by TAA + statins compared to TAA only. In vitro studies, using the BrdU method have shown that atorvastatin had no effect of hepatic stellate cells proliferation. Nevertheless, statin treatment was not associated with worsening of liver damage, portal hypertension or survival rate.

CONCLUSION: Atorvastatin or rosuvastatin did not inhibit TAA-induced liver cirrhosis or oxidative stress in rats. Whether statins may have therapeutic applications in hepatic fibrosis due to other etiologies deserve further investigation.

Fluvastatin inhibits angiotensin II-induced nuclear factor kappa B activation in renal tubular epithelial cells through the p38 MAPK pathway

3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitors has been shown to reduce the progression of renal disease independent of cholesterol-lowering effect, but the mechanism of potential protective effect remains unclear. Here, we investigate the effect of fluvastatin on activation of nuclear factor-κB (NF-κB) induced by angiotensin II (AngII) in rat kidney tubule epithelial cells (NRK-52E). Electrophoretic mobility shift assays (EMSA) was used to detect NF-κB activation. Phosphorylation of cellular p38 mitogen-activated protein kinase (p38MAPK) was determined by western blot analysis. AngII stimulated the DNA-binding activity of NF-κB and phosphorylation of p38MAPK in cultured NRK-52E cells in a dose-dependent (10(-9)-10(-6) mol/l) manner (P < 0.01). AngII (10(-6) mol/l) induced a rapid (5 min) increase of the p38MAPK phosphorylation. NF-κB DNA-binding activity was increased at as early as 30 min, peaked at 2 h after AngII treatment. This stimulatory effect of AngII on NF-κB was blocked by SB203580 (a specific inhibitor of p38MAPK). Incubation of cells with fluvastatin significantly inhibited the AngII-induced NF-κB activation in a dose-dependent (10(-7)-10(-5) mol/l) manner (P < 0.05). Exogenous mevalonate (10(-4)mol/l) prevented the effect of fluvastatin on NF-κB activation. These results suggest the fluvastatin reduced AngII-induced NF-κB activation via the p38MAPK pathway in NRK-52E cells. The effect is at least partly due to blocking the biosynthesis of mevalonate.

Simvastatin protects diabetic rats against kidney injury through the suppression of renal matrix metalloproteinase-9 expression

OBJECTIVE

To observe the effects of simvastatin on urinary excretion of matrix metalloproteinase-9 (MMP- 9), renal expression of MMP-9, and investigate its possible renoprotective mechanisms in streptozotocin (STZ)-induced diabetic rats.

METHOD

Twenty-four Wistar rats were divided into 3 groups: control healthy rats (group C, no.=8), untreated diabetic rats (group D, no.=8), and diabetic rats treated with simvastatin (20 mg/kg/d) (group S, no.=8). Peripheral blood glucose was tested weekly, glycosylated hemoglobin A1c (HbA1c), total cholesterol (TC), LDL cholesterol (LDL-C) levels, and urinary albumin (ALB) excretion rate as well as the urinary excretion rates of retinol-binding protein (RBP) and MMP-9 were tested at 8th week. The renal tissues of diabetic rats were obtained for evaluating kidney/ body weight ratio, observing renal pathological changes by electron microscope and examining the expression of renal MMP-9 mRNA by RT-PCR.

RESULTS

There was no statistical difference on the change of peripheral blood TC and LDL-C between group C and group D. Peripheral blood glucose, HbA1c levels kidney/body weight ratio urinary excretion rates of ALB, RBP, and MMP-9 concurrently with the expression of renal MMP-9 mRNA were significantly higher in groups D and S compared with group C (p<0.01). Treatment with simvastatin significantly lowered peripheral blood TC, LDL-C, kidney/body weight ratio, urinary excretion rates of ALB, RBP, and MMP-9 as well as the expression of renal MMP-9 mRNA (p<0.01); however, there was no evident effect on the change of blood glucose and HbA1c levels between group D and group S. In addition, urinary excretion rate of MMP-9 showed positive correlations with the urinary ALB excretion and urinary RBP excretion. Pathological lesions of the glomeruli and epithelial cells foot processes (FP) was lightened by simvastatin.

CONCLUSION

Simvastatin may has a potential therapeutic target in diabetic nephropathy, which may be partly attributed to down-regulating over-expression of MMP-9 in renal tissue.

Atorvastatin attenuates angiotensin II-induced inflammatory actions in the liver

Statins exert beneficial effects in chronically damaged tissues. Angiotensin II (ANG II) participates in liver fibrogenesis by inducing oxidative stress, inflammation, and transforming growth factor-beta1 (TGF-beta1) expression. We investigate whether atorvastatin modulates ANG II-induced pathogenic effects in the liver. Male Wistar rats were infused with saline or ANG II (100 ng kg(-1) min(-1)) for 4 wk through a subcutaneous osmotic pump. Rats received either vehicle or atorvastatin (5 mg kg(-1) day(-1)) by gavage. ANG II infusion resulted in infiltration of inflammatory cells (CD43 immunostaining), oxidative stress (4-hydroxynonenal), hepatic stellate cells (HSC) activation (smooth muscle alpha-actin), increased intercellular adhesion molecule (ICAM-1), and interleukin-6 hepatic gene expression (quantitative PCR). These effects were markedly blunted in rats receiving atorvastatin. The beneficial effects of atorvastatin were confirmed in an additional model of acute liver injury (carbon tetrachloride administration). We next explored whether the beneficial effects of atorvastatin on ANG II-induced actions are also reproduced at the cellular level. We studied HSC, a cell type with inflammatory and fibrogenic properties. ANG II (10(-8)M) stimulated cell proliferation, proinflammatory actions (NF-kappaB activation, ICAM-1 expression, interleukin-8 secretion) as well as expression of procollagen-alpha(1(I)) and TGF-beta1. All of these effects were reduced in the presence of atorvastatin (10(-7)M). These results indicate that atorvastatin attenuates the pathogenic events induced by ANG II in the liver both in vivo and in vitro. Therefore, statins could have beneficial effects in conditions characterized by hepatic inflammation.

Lovastatin inhibits oxidized low-density lipoprotein-induced plasminogen activator inhibitor and transforming growth factor-beta1 expression via a decrease in Ras/extracellular signal-regulated kinase activity in mesangial cells

Oxidized low-density lipoprotein (Ox-LDL) might be involved in the progression of renal disease. Ox-LDL stimulation of plasminogen activator inhibitor-1 (PAI-1) expression via transforming growth factor-beta (TGF-beta)/Smad signaling in mesangial cells required activation of extracellular signal-regulated kinase (ERK). Mevalonate depletion by 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase inhibitors, or statins, decreases the levels of farnesyl pyrophosphate (FPP) for isoprenylation of Ras. We postulate that statins may ameliorate the Ox-LDL-induced mesangial matrix accumulation by inhibiting Ras/ERK activation with subsequent downregulation of TGF-beta target genes. Quiescent mesangial cells were incubated for 18 h with and without the presence of lovastatin before 50 microg/mL of Ox-LDL treatment for 1 h. Lovastatin inhibited markedly the stimulatory effects of Ox-LDL on ERK1/2 activation, nuclear Smad3 expression, TGF-beta1 and PAI-1 mRNA and protein expression, and PAI-1 luciferase activity. These inhibitory effects of lovastatin were reversed almost completely by mevalonate or FPP. Similar to lovastatin, FTI-277, which is an inhibitor of Ras farnesylation, decreased the Ox-LDL-induced activation of ERK/Smad3 and induction of TGF-beta1/PAI-1. These results indicate that lovastatin prevents the Ox-LDL-induced Ras/ERK activation that results in inhibition of Smad3 activation in mesangial cells with subsequent downregulation of TGF-beta target genes. Thus, statins seem to have antifibrotic effects through their anti-TGF-beta response that are relevant in the treatment of chronic renal disease with dyslipidemia.

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.

Differential effects of simvastatin on mesangial cells

BACKGROUND

Statins are increasingly recognized as mediators of direct cellular effects independent of their lipid lowering capacity. Therefore, the time and concentration dependence of various statin-mediated cellular alterations was compared in renal mesangial cells.

METHODS

The effects of statins on cell proliferation, gene expression, cytoskeletal alterations, apoptosis, and cytotoxicity were analyzed in cultured mesangial cells using standard techniques.

RESULTS

Simvastatin and lovastatin decreased proliferation and cell number of rat mesangial cells concentration-dependently. Concurrently, the expression of the fibrogenic protein connective tissue growth factor (CTGF) was impaired and actin stress fibers, which are typical of mesangial cells in culture, became disassembled by simvastatin. A decrease of the posttranslational modification of RhoA by geranylgeranyl moieties was detected, supporting a role for RhoA as mediator of statin effects. Induction of apoptosis, determined by activation of caspase-3 and DNA fragmentation, and necrosis only occurred at later time points, when the morphology of the cells was strongly altered and the cells detached from the surface due to changes in the actin cytoskeleton. Basically, the same results were obtained with a human mesangial cell line. Furthermore, statin effects were mimicked by inhibition of the geranylgeranyltransferase.

CONCLUSION

Most of the cellular effects of the lipophilic statins occurred within the same time and concentration range, suggesting a common molecular mechanism. Only apoptosis and necrosis were observed at later time points or with higher concentrations of simvastatin and thus seem to be secondary to the changes in gene expression and alterations of the actin cytoskeleton.

Fluvastatin prevents nephropathy likely through suppression of connective tissue growth factor-mediated extracellular matrix accumulation

Diabetic nephropathy is related to glomerular extracellular matrix (ECM) accumulation that leads to glomerulosclerosis. Fluvastatin as a lipid-lowering medicine significantly prevents diabetic nephropathy, probably not only through its lipid-lowering action, but also mainly through its direct suppression of glomerular ECM accumulation. To test this hypothesis, in the present study, a five-sixths nephrectomized (5/6Nx) rat model to induce a renal ECM accumulation without coexistence of hyperlipidemia was used to investigate the effect of fluvastatin on renal function, glomerular ECM accumulation and expression of connective tissue growth factor (CTGF). 5/6Nx induced a significant nephropathy in rats at 13 weeks, indicated by renal dysfunction including increases in blood urine nitrogen, creatinine and urinary protein excretion, and renal histopathological changes. Administration of fluvastatin significantly prevented the renal dysfunction and histological abnormalities in the 5/6Nx rats. Furthermore, both significant suppression of matrix metalloproteinases (MMPs) activity such as MMP-2 and significant activation of tissue inhibitors of MMP (TIMPs) such as TIMP-2 observed in the 5/6Nx rats were almost completely prevented by fluvastatin, resulting in a significant prevention of glomerular ECM accumulation. For upstream mediator of ECM accumulation, 5/6Nx significantly up-regulated CTGF mRNA expression, but fluvastatin treatment prevented CTGF up-regulation. These results suggest that fluvastatin, as one of well-known lipid-lowering agents, plays an important role in the prevention of nephropathy, likely through suppression of CTGF-mediated ECM accumulation. Therefore, fluvastatin may be a potential candidate for developing a pharmaceutical approach to the prevention of diabetic nephropathy due to its both lipid-lowering and direct anti-renal ECM accumulation actions.

Cerivastatin inhibits proliferation of interleukin-1β-induced rat mesangial cells by enhanced formation of nitric oxide

The antiproliferative effect of statins on mesangial cells could represent a new therapeutic approach in glomerulonephritis. We studied in rat mesangial cells whether the antiproliferative action of cerivastatin on mesangial cells may be mediated by mesangial nitric oxide (NO) formation due to the inducible NO synthase (iNOS) or by induction of cyclooxygenase-2. Mesangial cells were stimulated with interleukin-1 beta and treated with cerivastatin for 24 h. Cell proliferation was examined by bromodeoxy-uridine (BrdU) incorporation, and nitrite and prostaglandin production was measured in supernatants as a means for iNOS or cyclooxygenase-2 activity. iNOS and cyclooxygenase-2 expression was quantified by Northern and Western blot analyses. Cerivastatin (0.0625 microM) significantly inhibited DNA synthesis in interleukin-1 beta-stimulated mesangial cells without altering cell viability. Interleukin-1 beta-induced nitrite production was twofold increased by 0.05 microM cerivastatin, and this effect could be reversed by addition of 100 microM mevalonate. iNOS mRNA levels increased sixfold (33% of maximum) in cerivastatin-treated mesangial cells as compared with vehicle-treated controls (3.5% of maximum). iNOS and cyclooxygenase-2 protein expression increased threefold (iNOS: 2.77+/-0.53/cyclooxygenase-2: 3.49+/-1.25). The NOS inhibitors N-methyl-L-arginine (L-NMMA) and L-N6-(1-iminoethyl)lysine (L-NIL) reversed the antiproliferative effect of cerivastatin. The cyclooxygenase-2 inhibitor celecoxib did not alter DNA synthesis and iNOS or cyclooxygenase-2 expression, but blocked prostacyclin production in interleukin-1 beta and cerivastatin-treated mesangial cells. In conclusion, cerivastatin increased cytokine-induced iNOS and cyclooxygenase-2 expression, thus constituting NO-regulated growth inhibition of mesangial cells.

Effect of HMG-CoA reductase inhibitors on proliferation and protein synthesis by rat hepatic stellate cells

BACKGROUND/AIMS

3-Hydroxy-3-methylglutaryl coenzyme A reductase inhibitors called statins, have besides their cholesterol-lowering function, therapeutic value in conditions such as neo-angiogenesis and atherosclerosis. We investigated the effect of two statins on the proliferation rate and protein steady state levels of hepatic stellate cells (HSC).

METHODS

Cellular DNA synthesis under the influence of statins and/or platelet derived growth factor (PDGF) and mevalonate was evaluated by measuring BrdU incorporation. Synthesis of collagens type I, III, IV and fibronectin was quantified by ELISA. Additionally, we examined the influence of simvastatin on isoprenylation of Ras and RhoA proteins.

RESULTS

Lovastatin and simvastatin induced a dose-dependent inhibition of the proliferation rate of HSC. Subsequent addition of PDGF and/or mevalonate, after long-term exposure of simvastatin to HSC, did not reverse simvastatins' antiproliferative effect. Lovastatin and simvastatin reduced the protein steady state level of collagens type I (-40%), III (-45%) and IV (-27%). Membrane bound Ras steady state levels decreased under the influence of simvastatin. Membrane bound RhoA remained unaltered, whereas, cytosolic RhoA protein level was strongly reduced.

CONCLUSIONS

Our data showed that lovastatin and simvastatin inhibited HSC proliferation and collagen steady state levels by mechanisms independent of their lipid reducing activities.

Effect of simvastatin on renal function in autosomal dominant polycystic kidney disease

BACKGROUND

In animal models, HMG-CoA reductase inhibitors were able to improve renal function and endothelium-dependent vascular reactivity. In various experimental renal diseases, including autosomal dominant polycystic kidney disease (ADPKD), HMG-CoA reductase inhibitors improved the rate of decline in renal function. We studied the effect of simvastatin on ADPKD patients.

METHODS

In a double-blind cross-over study, 10 normocholesterolaemic ADPKD patients were treated in random order for 4 weeks with 40 mg simvastatin or placebo daily. After each treatment period, we investigated the effect of simvastatin on renal blood flow and endothelium-dependent vascular reactivity. These periods were separated by a 4-week wash-out period.

RESULTS

After treatment with simvastatin, glomerular filtration rate (GFR) significantly increased from 124+/-4 ml/min to 132+/-6 ml/min (P<0.05). Simultaneously, effective renal plasma flow (ERPF) increased significantly from 494+/-30 ml/min to 619+/-67 ml/min after simvastatin treatment (P<0.05). These renal effects were accompanied by a significantly enhanced vasodilator response to acetylcholine in the forearm after simvastatin treatment. Total serum cholesterol levels were significantly reduced after treatment with simvastatin, from 4.24+/-0.32 to 3.17+/-0.22 mmol/l (P<0.001).

CONCLUSION

We concluded that simvastatin treatment can ameliorate renal function in ADPKD patients, by increasing renal plasma flow, possibly via improvement of endothelial function. Long-term clinical trials with HMG-CoA reductase inhibitors are needed to confirm these results and to establish a chronic inhibiting effect of HMG-CoA reductase inhibitors on the progression towards end-stage renal disease in ADPKD patients.