The effect of high-dose simvastatin on free fatty acid metabolism in patients with type 2 diabetes mellitus

Effects of simvastatin on the mevalonate pathway and cell wall integrity of Staphylococcus aureus

AIMS

To investigate the effects of simvastatin as an antimicrobial, considering its influence on the mevalonate pathway and the bacterial cell wall of S. aureus.

METHODS AND RESULTS

S. aureus ATCC 29213 and 33591 were exposed to simvastatin in the presence of exogenous mevalonate to determine whether mevalonate could reverse the inhibition. S. aureus was also treated with simvastatin and gene expression analysis assays were performed to evaluate genes associated with the mevalonate pathway (mvaA, mvaS, mvaK1, and mvaK2), peptidoglycan synthesis (uppS, uppP, and murG), and cell wall stress (vraX, sgtB, and tcaA). Transmission electron microscopy was used to identify the presence of morphological changes. The data were compared using two-way ANOVA and Bonferroni post-test, or the Mann-Whitney test. Addition of exogenous mevalonate was able to partially or completely reverse the inhibition caused by simvastatin. A significant increase of the vraX gene and a reduction of the mvaA gene were observed, together with changes in bacterial morphology.

CONCLUSION

Simvastatin can exert its antimicrobial effect by means of changes in the cell wall associated with the mevalonate pathway.

Lipoprotein lipase as a target for obesity/diabetes related cardiovascular disease

Worldwide, the prevalence of obesity and diabetes have increased, with heart disease being their leading cause of death. Traditionally, the management of obesity and diabetes has focused mainly on weight reduction and controlling high blood glucose. Unfortunately, despite these efforts, poor medication management predisposes these patients to heart failure. One instigator for the development of heart failure is how cardiac tissue utilizes different sources of fuel for energy. In this regard, the heart switches from using various substrates, to predominantly using fatty acids (FA). This transformation to using FA as an exclusive source of energy is helpful in the initial stages of the disease. However, over the progression of diabetes this has grave end results. This is because toxic by-products are produced by overuse of FA, which weaken heart function (heart disease). Lipoprotein lipase (LPL) is responsible for regulating FA delivery to the heart, and its function during diabetes has not been completely revealed. In this review, the mechanisms by which LPL regulates fuel utilization by the heart in control conditions and following diabetes will be discussed in an attempt to identify new targets for therapeutic intervention. Currently, as treatment options to directly target diabetic heart disease are scarce, research on LPL may assist in drug development that exclusively targets fuel utilization by the heart and lipid accumulation in macrophages to help delay, prevent, or treat cardiac failure, and provide long-term management of this condition during diabetes.

Correlations between genetically predicted lipid-lowering drug targets and inflammatory bowel disease

BACKGROUND

Millions of individuals globally suffer from Inflammatory bowel diseases (IBDs). There is a dearth of large population-based investigations on lipid metabolism and IBDs, and it is unclear whether lipid-lowering drugs target IBDs causally. Consequently, the aim of this study was to investigate the effects of lipid-lowering medication targets on the occurrence and progression of IBDs.

METHODS

Among the more than 400,000 participants in the UK Biobank cohort and the more than 170,000 participants in the Global Lipids Genetics Consortium, a total of nine genes linked to lipid-lowering drug targets were obtained (ABCG5/ABCG8, APOB, APOC3, LDLR, LPL, HMGCR, NPC1L1, PCSK9, and PPARA). IBD data were acquired from de Lange et al. (patients/sample size of IBDs: 25042/59957; ulcerative colitis (UC): 12366/45,975; Crohn's disease (CD): 12194/40,266) and the FinnGen cohort (patients/total sample size of IBDs: 4420/176,899; CD: 1520/171,906; UC: 3325/173,711). All four datasets were cross-combined for validation via Mendelian randomization analysis, and potential mediating factors were explored via mediation analysis.

RESULTS

Genetically proxied APOC3 inhibition was related to increased IBD risk (odds ratio (95% confidence interval): 0.87 (0.80-0.95); P < 0.01) and UC risk (0.83 (0.73-0.94); P < 0.01). IBD and CD risk were reduced by genetic mimicry of LDLR and LPL enhancements, respectively (odds ratioLDLR: 1.18 (1.03-1.36); P = 0.018; odds ratioCD: 1.26 (1.11-1.43); P = 2.60E-04). Genetically proxied HMGCR inhibition was associated with increased CD risk (0.68 (0.50-0.94); P = 0.018). These findings were confirmed through Mendelian analysis of the cross-combination of four separate datasets. APOC3-mediated triglyceride levels may contribute to IBDs partly through mediated triglycerides, Clostridium sensu stricto 1, Clostridiaceae 1, or the Lachnospiraceae FCS020 group. LDLR enhancement may contribute to IBDs partly through increasing Lactobacillaceae.

CONCLUSION

Vigilance is required to prevent adverse effects on IBDs (UC) for patients receiving volanesorsen (an antisense oligonucleotide targeting ApoC3 mRNA) and adverse effects on CD for statin users. LPL and LDLR show promise as candidate drug targets for CD and IBD, respectively, with mechanisms that are potentially independent of their lipid-lowering effects.

Different Effects of Pravastatin on Preeclampsia-like Symptoms in Different Mouse Models

Background

Pravastatin (Pra) exerts protective effects on preeclampsia. Preeclampsia is a multifactorial and pathogenic pathway syndrome. The present study compared the effects of Pra on clinical manifestations of preeclampsia in different pathogenic pathways.

Methods

Two different preeclampsia-like mouse models used in this study were generated with Nω-nitro-L-arginine methyl ester (L-NAME) and used lipopolysaccharide (LPS) from day 7 of gestation, respectively. Pra treatment was administered on day 2 after the models were established in each group (L-NAME + Pra, LPS + Pra, and Control + Pra, n = 8) or normal saline (NS) for the control group (L-NAME + NS, LPS + NS, and Control + NS, n = 8). Maternal weight, serum lipids, the histopathological changes, and lipid deposition in the liver and placenta were observed. The pregnancy outcomes were compared. The blood pressure analysis was carried out on repeated measurements of variance. Student's t-test was used for comparing the two groups. The enumeration data were compared by Chi-square test.

Results

The mean arterial pressure (MAP) and 24-h urinary protein in the L-NAME + NS and LPS + NS groups were significantly higher than the Control + NS group (F = 211.05 and 309.92 for MAP, t = 6.63 and 8.63 for 24-h urinary protein; all P < 0.05) and reduced in the L-NAME + Pra group as compared to the L-NAME + NS group (F = 208.60 for MAP, t = 6.77 for urinary protein; both P < 0.05). Urinary protein was decreased in the LPS + Pra group as compared to the LPS + NS group (t = 5.33; P < 0.05), whereas MAP had no statistical significance (F = 3.37; P > 0.05). Compared to the Control + NS group, the placental efficiency in the L-NAME + NS and LPS + NS groups decreased significantly (t = 3.09 and 2.89, respectively; both P < 0.05); however, no significant difference was observed in L-NAME + Pra and LPS + Pra groups (t = 1.37 and 0.58, respectively; both P > 0.05). Free fatty acid was elevated in the L-NAME + NS group as compared to the Control + NS group (t = 3.99; P < 0.05) at day 18 of pregnancy and decreased in the L-NAME + Pra group as compared to the L-NAME + NS group (t = 3.28; P < 0.05); however, no significant change was observed in the LPS model (F = 0.32; P > 0.05).

Conclusion

This study suggested that Pra affected the clinical manifestations differently in preeclampsia-like mouse models generated in various pathogenic pathways.

Emerging strategies of targeting lipoprotein lipase for metabolic and cardiovascular diseases

Although statins and other pharmacological approaches have improved the management of lipid abnormalities, there exists a need for newer treatment modalities especially for the management of hypertriglyceridemia. Lipoprotein lipase (LPL), by promoting hydrolytic cleavage of the triglyceride core of lipoproteins, is a crucial node in the management of plasma lipid levels. Although LPL expression and activity modulation is observed as a pleiotropic action of some the commonly used lipid lowering drugs, the deliberate development of drugs targeting LPL has not occurred yet. In this review, we present the biology of LPL, highlight the LPL modulation property of currently used drugs and review the novel emerging approaches to target LPL.

Statin therapy and plasma free fatty acids: a systematic review and meta-analysis of controlled clinical trials

AIM

The aim of this meta-analysis was to evaluate the effect of statin therapy on plasma FFA concentrations in a systematic review and meta-analysis of controlled clinical trials.

METHODS

PubMed-Medline, SCOPUS, Web of Science and Google Scholar databases were searched (from inception to February 16 2015) to identify controlled trials evaluating the impact of statins on plasma FFA concentrations. A systematic assessment of bias in the included studies was performed using the Cochrane criteria. A random effects model and generic inverse variance method were used for quantitative data synthesis. Sensitivity analysis was conducted using the leave-one-out method. Random effects meta-regression was performed using unrestricted maximum likelihood method to evaluate the impact of potential moderators.

RESULTS

Meta-analysis of data from 14 treatment arms indicated a significant reduction in plasma FFA concentrations following treatment with statins (weighted mean difference (WMD) -19.42%, 95% CI -23.19, --15.64, P < 0.001). Subgroup analysis confirmed the significance of the effect with both atorvastatin (WMD -20.56%, 95% CI -24.51, -16.61, P < 0.01) and simvastatin (WMD -18.05%, 95% CI -28.12, -7.99, P < 0.001). Changes in plasma FFA concentrations were independent of treatment duration (slope -0.10, 95% CI -0.30, 0.11, P = 0.354) and magnitude of reduction in plasma low density lipoprotein cholesterol concentrations (slope 0.55, 95% CI -0.17, 1.27, P = 0.133) by statins.

CONCLUSIONS

The results of the present study suggest that statin therapy may lower plasma FFA concentrations. The cardiovascular and metabolic significance of this finding requires further investigation.

Possible Involvement of Palmitate in Pathogenesis of Periodontitis

Type 2 diabetes (T2D) is characterized by decreased insulin sensitivity and higher concentrations of free fatty acids (FFAs) in plasma. Among FFAs, saturated fatty acids (SFAs), such as palmitate, have been suggested to promote inflammatory responses. Although many epidemiological studies have shown a link between periodontitis and T2D, little is known about the clinical significance of SFAs in periodontitis. In this study, we showed that gingival fibroblasts have cell-surface expression of CD36, which is also known as FAT/fatty acid translocase. Moreover, CD36 expression was increased in gingival fibroblasts of high-fat diet-induced T2D model mice, compared with gingival fibroblasts of mice fed a normal diet. DNA microarray analysis revealed that palmitate increased mRNA expression of pro-inflammatory cytokines and chemokines in human gingival fibroblasts (HGF). Consistent with these results, we confirmed that palmitate-induced interleukin (IL)-6, IL-8, and CXCL1 secretion in HGF, using a cytokine array and ELISA. SFAs, but not an unsaturated fatty acid, oleate, induced IL-8 production. Docosahexaenoic acid (DHA), which is one of the omega-3 polyunsaturated fatty acids, significantly suppressed palmitate-induced IL-6 and IL-8 production. Treatment of HGF with a CD36 inhibitor also inhibited palmitate-induced pro-inflammatory responses. Finally, we demonstrated that Porphyromonas gingivalis (P.g.) lipopolysaccharide and heat-killed P.g. augmented palmitate-induced chemokine secretion in HGF. These results suggest a potential link between SFAs in plasma and the pathogenesis of periodontitis.

Effects of acute glucocorticoid blockade on metabolic dysfunction in patients with Type 2 diabetes with and without fatty liver

To investigate the potential of therapies which reduce glucocorticoid action in patients with Type 2 diabetes we performed a randomized, double-blinded, placebo-controlled crossover study of acute glucocorticoid blockade, using the glucocorticoid receptor antagonist RU38486 (mifepristone) and cortisol biosynthesis inhibitor (metyrapone), in 14 men with Type 2 diabetes. Stable isotope dilution methodologies were used to measure the rates of appearance of glucose, glycerol, and free fatty acids (FFAs), including during a low-dose (10 mU·m⁻² ·min⁻¹) hyperinsulinemic clamp, and subgroup analysis was conducted in patients with high or low liver fat content measured by magnetic resonance spectroscopy (n = 7/group). Glucocorticoid blockade lowered fasting glucose and insulin levels and improved insulin sensitivity of FFA and glycerol turnover and hepatic glucose production. Among this population with Type 2 diabetes high liver fat was associated with hyperinsulinemia, higher fasting glucose levels, peripheral and hepatic insulin resistance, and impaired suppression of FFA oxidation and FFA and glycerol turnover during hyperinsulinemia. Glucocorticoid blockade had similar effects in those with and without high liver fat. Longer term treatments targeting glucocorticoid action may be useful in Type 2 diabetes with and without fatty liver.

Correlation between serum free fatty acids levels and Gensini score in elderly patients with coronary heart disease

Objectives

To investigate the relationship between serum free fatty acids (FFAs) levels and the severity of coronary artery lesions in elderly patients with coronary heart disease (CAD).

Methods

A total of 172 elderly patients who underwent coronary angiography were divided into CAD group (n = 128) and non-CAD group (n = 44) according to the results of coronary angiography. Serum FFAs and lipid levels were measured and the Gensini score were calculated.

Results

No matter the differences between age, gender and the usage of statins or not, there was no statistical significance in FFAs levels (P > 0.05). In terms of the Gensini score, it was higher in patients aged 70–79 years than in patients 60–69 years old [15.00 (5.00, 34.00) vs. 10.00 (2.00, 24.00), P < 0.05], higher in men than women [14.00 (4.00, 34.00) vs. 7.00 (2.50, 19.75), P < 0.05], and higher in patients on statins [13.50 (4.25, 33.50) vs. 6.50 (2.00, 18.00), P < 0.05]. The serum FFAs levels [449.50 (299.00, 624.75) mEq/L vs. 388.00 (258.50, 495.25) mEq/L, P < 0.05] and Gensini score [17.50 (8.00, 41.75) vs. 1.00 (0, 5.00), P < 0.05] were higher in the CAD group than in the non-CAD group. In the CAD group, there was no statistical significance in FFAs levels among patients with different numbers of diseased coronary vessels (P > 0.05). Furthermore, the FFAs levels were positively correlated with the Gensini score (r = 0.394, P = 0.005). Regression analysis showed that the FFAs levels were related to the Gensini score independently after adjusting for the other risk factors.

Conclusions

The serum FFAs levels were associated with the Gensini score in elderly patients with CAD. It might indicate FFAs as a biomarker predicting the severity of coronary artery lesions.

Atherogenic dyslipidemia and combination pharmacotherapy in diabetes: recent clinical trials

Patients with type 2 diabetes (T2D) are at a markedly increased risk of cardiovascular disease (CVD). Dyslipidemia is a common risk factor and a strong predictor of CVD in T2D patients. Although statins decrease the incidence of CVD in T2D, residual cardiovascular risk remains high despite the achievement of optimal or near-optimal plasma low-density lipoprotein (LDL) cholesterol concentrations. This may, in part, be due to uncorrected atherogenic dyslipidemia. Hypertriglyceridemia, the driving force behind diabetic dyslipidemia, results from hepatic overproduction and/or delayed clearance of triglyceride-rich lipoproteins. In patients treated with a statin to LDL-cholesterol goals, the addition of ezetimibe, fenofibrate, niacin, or n-3 fatty acid ethyl esters may be required to correct the persistent atherogenic dyslipidemia. Clinical trial evidence describing best practice is limited, but recent data supports the strategy of adding fenofibrate to a statin, and suggests specific benefits in dyslipidemic patients and in the improvement of diabetic retinopathy. However, based on results from a recent clinical trial, niacin should not be added to a statin in individuals with low high-density lipoprotein cholesterol and very well controlled LDL-cholesterol. Further evidence is required to support the role of ezetimibe and n-3 fatty acids in treating residual CVD risk in statin-treated T2D patients.

Atherogenic dyslipidemia and combination pharmacotherapy in diabetes: recent clinical trials

Patients with type 2 diabetes (T2D) are at a markedly increased risk of cardiovascular disease (CVD). Dyslipidemia is a common risk factor and a strong predictor of CVD in T2D patients. Although statins decrease the incidence of CVD in T2D, residual cardiovascular risk remains high despite the achievement of optimal or near-optimal plasma low-density lipoprotein (LDL) cholesterol concentrations. This may, in part, be due to uncorrected atherogenic dyslipidemia. Hypertriglyceridemia, the driving force behind diabetic dyslipidemia, results from hepatic overproduction and/or delayed clearance of triglyceride-rich lipoproteins. In patients treated with a statin to LDL-cholesterol goals, the addition of ezetimibe, fenofibrate, niacin, or n-3 fatty acid ethyl esters may be required to correct the persistent atherogenic dyslipidemia. Clinical trial evidence describing best practice is limited, but recent data supports the strategy of adding fenofibrate to a statin, and suggests specific benefits in dyslipidemic patients and in the improvement of diabetic retinopathy. However, based on results from a recent clinical trial, niacin should not be added to a statin in individuals with low high-density lipoprotein cholesterol and very well controlled LDL-cholesterol. Further evidence is required to support the role of ezetimibe and n-3 fatty acids in treating residual CVD risk in statin-treated T2D patients.

Monacolin K affects lipid metabolism through SIRT1/AMPK pathway in HepG2 cells

Monacolin K is the secondary metabolite isolated from Monascus spp. It is the natural form of lovastatin, which is clinically used to reduce the synthesis of cholesterol by inhibiting 3-hydroxy-3-methylglutaryl coenzyme A reductase. In the present study, monacolin K increased protein expression of SIRT1 and phosphorylation level of AMP-activated protein kinase (AMPK) in HepG2 cells. Through activation of SIRT1/AMPK pathway, monacolin K increased phosphorylation of acetyl CoA carboxylase and caused nuclear translocation of forkhead box O1. The western blotting results showed that monacolin K increased expression of adipose triglyceride lipase but decreased abundances of fatty acid synthase (FAS) and sterol regulatory element-binding protein 1 (SREBP1). Monacolin K also decreased the intracellular accumulation of lipids as demonstrated by Oil Red O staining. In addition, the immunostaining showed that monacolin K prevented the nuclear translocation of SREBP1, indicating the association with down-regulation of FAS. All the demonstrated effects of monacolin K were counteracted by nicotinamide or compound C, the inhibitors of SIRT1 or AMPK. In summary, monacolin K reduces the lipid content through SIRT1/AMPK pathway in HepG2 cells, which promotes catabolism and inhibits anabolism of lipid.

Effects of free fatty acids on human salivary gland epithelial cells

Obesity and type 2 diabetes (T2D) are characterized by decreased insulin sensitivity and higher concentrations of free fatty acids (FFAs) in plasma. Among FFAs, saturated fatty acids (SFAs), such as palmitate, have been proposed to promote inflammatory responses. Primary Sjögren's syndrome (SS) is an autoimmune disease characterized by inflammatory mononuclear cell infiltration and destruction of epithelial cells in the salivary and lacrimal glands. IL-6 production and α-fodrin degradation are increased in salivary gland epithelial cells of patients with primary SS. Although previous studies have shown a link between SS and either dyslipidemia or T2D, little is known about the clinical significance of FFAs in primary SS. Here we report that SFAs, but not unsaturated fatty acids, induced IL-6 production via NF-κB and p38 MAPK activation in human salivary gland epithelial cells. Moreover, palmitate induced apoptosis and α-fodrin degradation by caspase-3 activation. Unlike salivary gland epithelial cells, induction of IL-6 production and the degradation of α-fodrin in response to palmitate were undetectable in squamous carcinoma cells and keratinocytes. Taken together, SFAs induced IL-6 production and α-fodrin degradation in salivary gland epithelial cells, implicating a potential link between the pathogenesis of primary SS and SFAs level in plasma.

Palmitate induces apoptosis in Schwann cells via both ceramide-dependent and independent pathways

Peripheral neuropathy has been reported to prevail in obese or pre-diabetic individuals, yet its etiology remains unknown. Palmitate, a saturated fatty acid increased in obesity and diabetes, is known to induce apoptosis in multiple types of cells and this effect may be mediated by ceramide, a member of the sphingolipid family. To clarify whether de novo ceramide synthesis from palmitate contributes to apoptosis of Schwann cells, we cultured immortalized mouse Schwann cells (IMS) and rat primary Schwann cells with palmitate, a ceramide analogue C2-ceramide as well as inhibitors of the de novo ceramide synthesis (myriocin and fumonisin B1). Apoptosis of IMS detected by nuclear staining and cell membrane inversion was significantly increased by incubation with palmitate for 48 h in a dose-dependent fashion. This enhanced apoptosis was partially but significantly suppressed by myriocin and fumonisin B1. Western blot analysis and immunostaining revealed that palmitate clearly activated caspase-3 in IMS. Unexpectedly, the ceramide synthesis inhibitors failed to suppress the palmitate-induced caspase-3 activation in spite of complete restoration in ceramide accumulation. The results seemed relevant to the observations that C2-ceramide did not activate caspase-3 while provoking apoptosis with a clear dose-dependency. In agreement, the pro-apoptotic action of C2-ceramide was not attenuated by caspase inhibitors that partially suppressed palmitate-induced apoptosis. These results in IMS were well reproducible in rat primary Schwann cells, indicating that the observed phenomena are not specific to the cell line. Collectively, we have reached a conclusion that palmitate induces apoptosis in Schwann cells via both a ceramide-mediated, caspase-3-independent pathway and ceramide-independent, caspase-3-dependent pathways. Given the fact that palmitate and ceramide are increased in obese or pre-diabetic subjects, these lipids may be implicated in the pathogenesis of peripheral neuropathy observed in these disorders.

The use of statins potentiates the insulin-sensitizing effect of exercise training in obese males with and without Type 2 diabetes

Exercise training is advocated in insulin resistance and statins are used to treat hyperlipidaemia, two cardiometabolic risk factors often presenting concurrently. Statin intake may blunt mitochondrial function and the adaptive response to exercise training. Thus combining exercise training with statin administration may have adverse effects. We examined whether improvements in cardiometabolic risk factors, insulin sensitivity and mitochondrial function mediated by progressive exercise training are affected by statin use. A group of 14 obese elderly males on statins (ST) and 22 matched control subjects (C) were examined. Results on in vivo mitochondrial function [MRS (magnetic resonance spectroscopy)], mitochondrial density (Western blotting), insulin sensitivity (clamp) and metabolic flexibility (indirect calorimetry) were compared before and after a 12-week combined progressive exercise training programme (3 x per week; 45 min per session). Except for LDL (low-density lipoprotein) cholesterol, all pre-training values were comparable between statin users and control subjects. In vivo mitochondrial function and mitochondrial density improved by training in both groups. Interestingly, blood-lipid profile, insulin sensitivity (+72%), non-oxidative and oxidative glucose disposal (+38% and +112%) and insulin-mediated suppression of fat oxidation (-62%) improved only in the ST group. We conclude that statin treatment did not impede exercise performance or tolerance, mitochondrial function or mass. In addition, training-induced improvements in glucose homoeostasis were preserved in the ST group. Strikingly, the insulin-sensitizing effect of training was more prominent in the ST group than in the C group. The combined prescription of statins along with exercise training is safe and should be considered for subjects prone to develop insulin resistance.

Rediscovering bile acid sequestrants

AIM

In the recently published The Justification for the Use of statins in Primary prevention: an Intervention Trial Evaluating Rosuvastatin (JUPITER) mega-trial, rosuvastatin significantly reduced cardiovascular events at the expense of a small but significant increase in the risk of developing type 2 diabetes. The increased risk of new-onset diabetes was in keeping with a recent meta-analysis which suggested that statins, with the possible exception of pravastatin, marginally increase the risk of developing type 2 diabetes.

METHODS

Although the net effect of rosuvastatin was obviously very positive, we hypothesized that the addition of a bile aid sequestrant to a statin would not only further decrease lipid levels and potentially further decrease cardiovascular events but also protect against the development of diabetes. This is particularly relevant because the bile acid sequestrant, colesevelam, has recently been approved for therapy of diabetes.

RESULTS

Colesevelam like other bile acid sequestrants lowers low-density lipoprotein levels by 16% and C-reactive protein by 22% beyond the reductions that occur with statin therapy alone. Bile acid sequestrants confer lipid-lowering, glucose-lowering, and anti-inflammatory benefits, and have been shown to reduce risk of cardiovascular events.

CONCLUSIONS

Therefore, colesevelam should be the most effective and logical agent to add to a statin in the diabetic and insulin-resistant patient, because in addition to lowering cardiac risk it may prevent the development of diabetes, as well as improving glycaemic control in the established diabetic patient.

Myotoxic reactions to lipid-lowering therapy are associated with altered oxidation of fatty acids

Despite exceptional efficacy and safety, fear of muscle toxicity remains a major reason statins are underutilized. Evidence suggests that statin muscle toxicity may be mediated by abnormalities in lipid metabolism. To test the hypothesis that myotubes from patients intolerant of lipid-lowering therapies have abnormal fatty acid oxidation (FAO) responses we compared muscle from 11 subjects with statin intolerance (Intolerant) with muscle from seven statin-naive volunteers undergoing knee arthroplasty (Comparator). Gross muscle pathology was graded and skeletal muscle cell cultures were produced from each subject. FAO was assessed following treatment with increasing statin concentrations. There was no difference in muscle biopsy myopathy scores between the groups. Basal octanoate oxidation was greater in Intolerant than in Comparator subjects (P = 0.03). Lovastatin-stimulated palmitate oxidation tended to be greater for Intolerant compared to Control subjects' myotubes (P = 0.07 for 5 microM and P = 0.06 for 20 microM lovastatin). In conclusion abnormalities in FAO of Intolerant subjects appear to be an intrinsic characteristic of these subjects that can be measured in their cultured myotubes.

Effects of high-dose simvastatin therapy on glucose metabolism and ectopic lipid deposition in nonobese type 2 diabetic patients

OBJECTIVE

Statins may exert pleiotropic effects on insulin action that are still controversial. We assessed effects of high-dose simvastatin therapy on peripheral and hepatic insulin sensitivity, as well as on ectopic lipid deposition in patients with hypercholesterolemia and type 2 diabetes.

RESEARCH DESIGN AND METHODS

We performed a randomized, double-blind, placebo-controlled, single-center study. Twenty patients with type 2 diabetes received 80 mg simvastatin (BMI 29 +/- 4 kg/m2, age 55 +/- 6 years) or placebo (BMI 27 +/- 4 kg/m2, age 58 +/- 8 years) daily for 8 weeks and were compared with 10 healthy humans (control subjects; BMI 27 +/- 4 kg/m2, age 55 +/- 7 years). Euglycemic-hyperinsulinemic clamp tests combined with D-[6,6-d2]glucose infusion were used to assess insulin sensitivity (M) and endogenous glucose production (EGP). 1H magnetic resonance spectroscopy was used to quantify intramyocellular and hepatocellular lipids.

RESULTS

High-dose simvastatin treatment lowered plasma total and LDL cholesterol levels by approximately 33 and approximately 48% (P < 0.005) but did not affect M, intracellular lipid deposition in soleus and tibialis anterior muscles and liver, or basal and insulin-suppressed EGP. In simvastatin-treated patients, changes in LDL cholesterol related negatively to changes in M (r = -0.796, P < 0.01). Changes in fasting free fatty acids (FFAs) related negatively to changes in M (r = -0.840, P < 0.01) and positively to plasma retinol-binding protein-4 (r = 0.782, P = 0.008).

CONCLUSIONS

High-dose simvastatin treatment has no direct effects on whole-body or tissue-specific insulin action and ectopic lipid deposition. A reduction in plasma FFAs probably mediates alterations in insulin sensitivity in vivo.

The effect of statin alone or in combination with ezetimibe on postprandial lipoprotein composition in obese metabolic syndrome patients

INTRODUCTION

Fasting and postprandial hypertriglyceridemia are essential features of metabolic syndrome. Statins decrease fasting lipid levels but fail to reduce fat load induced hypertriglyceridemia. We established whether ezetimibe combined with simvastatin differently influences post fat load lipid levels and lipoprotein composition as compared to simvastatin 80mg monotherapy in obese male metabolic syndrome patients.

METHODS

Prospective, randomized, double blind, crossover trial. Male obese metabolic syndrome (ATPIII) patients (n=19) were treated with simvastatin 80mg and simvastatin/ezetimibe 10mg/10mg for 6 weeks. At the start of the study and after each treatment period oral fat loading tests were performed. Lipoprotein fractions (triglyceride-rich lipoproteins (TRL), IDL, LDL, and HDL) were isolated by density gradient ultracentrifugation. Postprandial changes in lipid levels were integrated as areas under the curve (AUCs).

RESULTS

Fasting LDL-C, RLP-C and triglycerides were lowered equally by both simvastatin 80mg and simvastatin/ezetimibe 10mg/10mg. Also postprandial plasma triglyceride levels (net AUC-TG) were equally lowered after both treatments (5.16+/-0.50mmolh/l after simvastatin/ezetimibe 10mg/10mg and 6.09+/-0.71mmolh/l after simvastatin 80mg) compared to fat loading without treatment (6.64+/-0.86mmolh/l). In addition, triglyceride-content in lipoprotein fractions after fat load (net AUCs) were also equally reduced after both treatments. Similarly, TRL. IDL and LDL cholesterol and apoB concentrations were equally affected by both treatment regimens, leading to a reduced number of circulating particles, in both conditions. However the composition of these particles remained the same.

CONCLUSION

Simvastatin 80mg and simvastatin/ezetimibe 10mg/10mg were equally effective in reducing fasting and post fat load plasma lipid, and lipoprotein concentrations and lipoprotein composition in obese metabolic syndrome patients.

Mutation of Tyr375 to Lys375 allows medium-chain acyl-CoA dehydrogenase to acquire acyl-CoA oxidase activity

Medium-chain acyl-CoA dehydrogenase (MCAD) and acyl-CoA oxidase (ACO) are key enzymes catalyzing the rate-determining step for the beta-oxidation of fatty acids. Tyr375 of MCAD is conserved in all acyl-CoA dehydrogenases and is an important residue for substrate binding. Four Tyr375 variant enzymes of rat liver MCAD were obtained through site-directed mutagenesis. Y375K was found to have intrinsic acyl-CoA oxidase activity, which was confirmed using HPLC analysis, while the wild-type and other Tyr375 variant enzymes did not show detectable oxidase activity. The kinetic parameters for the oxidase activity of Y375K variant enzyme were determined to be k(cat) of 320+/-80 h(-1) and K(M) of 30+/-15 microM using hexanoyl-CoA as the substrate. The oxidase activity of Y375K increased more than 200 times compared with that reported for the MCAD wild-type enzyme from mammalian sources. Molecular modeling study shows that the solvent accessible area for Y375K variant enzyme is wider than that of the wild-type enzyme, which indicates that Tyr375 may function as a switch against solvent accession. The mutation of this residue to Lys375 allows molecular oxygen to enter into the catalytic site serving as the electron acceptor for the reduced FAD cofactor.