Atorvastatin effects on SREBF1a and SCAP gene expression in mononuclear cells and its relation with lowering-lipids response

Cholesterol-Related lncRNAs as Response Predictors of Atorvastatin Treatment in Chilean Hypercholesterolemic Patients: A Pilot Study

Statins are currently the treatment of choice for hypercholesterolemia. However, wide interindividual variability has been observed in the response to treatment. Recent studies have reported the role of lncRNAs in the metabolism of lipids; nevertheless, there are few studies to date that show their role in the response to treatment with statins. Thus, the aim of this study was to assess the levels of expression of three lncRNAs (RP1-13D10.2; MANTIS; lncHR1) associated with genes involved in cholesterol homeostasis in leukocyte cells of hypercholesterolemic patients after treatment with atorvastatin and compare them with levels in subjects with normal cholesterol levels. A secondary aim was to assess the levels of expression in monocytic THP-1 cells differentiated to macrophages. The study included 20 subjects with normal cholesterol (NC) levels and 20 individuals with hypercholesterolemia (HC). The HC patients were treated with atorvastatin (20 mg/day/4 weeks). THP-1 cells were differentiated to macrophages with PMA and treated with different doses of atorvastatin for 24 h. Expression of lncRNAs was determined by RT-qPCR. The lncRNAs RP1-13D10.2 (p < 0.0001), MANTIS (p = 0.0013) and lncHR1 (p < 0.0001) presented increased expression in HC subjects compared with NC subjects. Furthermore, atorvastatin had a negative regulatory effect on the expression of lncHR1 (p < 0.0001) in HC subjects after treatment. In vitro, all the lncRNAs showed significant differences in expression after atorvastatin treatment. Our findings show that the lncRNAs tested present differential expression in HC patients and play a role in the variability reported in the response to atorvastatin treatment. Further research is needed to clarify the biological impact of these lncRNAs on cholesterol homeostasis and treatment with statins.

Pharmacogenomics of statins: lipid response and other outcomes in Brazilian cohorts

Statins are inhibitors of 3-hydroxy-3-methylglutaryl-CoA reductase, a key enzyme in cholesterol biosynthesis, that are highly effective in reducing plasma low-density lipoprotein (LDL) cholesterol and decreasing the risk of cardiovascular events. In recent years, a multitude of variants in genes involved in pharmacokinetics (PK) and pharmacodynamics (PD) have been suggested to influence the cholesterol-lowering response. However, the vast majority of studies have analyzed the pharmacogenetic associations in populations in Europe and the USA, whereas data in other populations, including Brazil, are mostly lacking. This narrative review provides an update of clinical studies on statin pharmacogenomics in Brazilian cohorts exploring lipid-lowering response, adverse events and pleiotropic effects. We find that variants in drug transporter genes (SLCO1B1 and ABCB1) positively impacted atorvastatin and simvastatin response, whereas variants in genes of drug metabolizing enzymes (CYP3A5) decreased response. Furthermore, multiple associations of variants in PD genes (HMGCR, LDLR and APOB) with statin response were identified. Few studies have explored statin-related adverse events, and only ABCB1 but not SLCO1B1 variants were robustly associated with increased risk in Brazil. Statin-related pleiotropic effects were shown to be influenced by variants in PD (LDLR, NR1H2) and antioxidant enzyme (NOS3, SOD2, MTHFR, SELENOP) genes. The findings of these studies indicate that statin pharmacogenomic associations are distinctly different in Brazil compared to other populations. This review also discusses the clinical implications of pharmacogenetic studies and the rising importance of investigating rare variants to explore their association with statin response.

High-Efficacy α,β-Dehydromonacolin S Improves Hepatic Steatosis and Suppresses Gluconeogenesis Pathway in High-Fat Diet-Induced Obese Rats

Isolated α,β-dehydromonacolin S (C5) from soil-derived fungus Aspergillus sclerotiorum PSU-RSPG178 was recently shown to exhibit an inhibitory effect against 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) activity in vitro. In this study, we investigated the effects of C5 on lipid-lowering, hepatic steatosis, and hepatic gluconeogenesis in vivo. The control rats received a daily dose of either vehicle or C5 at 10 mg/kg, while the high-fat diet-induced obese (HFD) rats were administered vehicle; 1, 3, or 10 mg/kg C5; or 10 mg/kg lovastatin (LO) for 6 weeks. C5 significantly improved dyslipidemia and diminished liver enzymes, HMGR activity, insulin resistance, and hepatic steatosis, comparable to LO without any hepatotoxicity and nephrotoxicity in HFD rats. A higher efficacy of C5 in lipid-lowering activity and anti-hepatic steatosis was associated with a significant decrease in genes involved in lipid metabolism including sterol regulatory element binding protein (SREBP) 1c, SREBP2, liver X receptor alpha (LXRα), and peroxisome proliferator-activated receptor (PPAR) gamma (PPARγ) together with an increase in the PPAR alpha (PPARα). Correspondingly, C5 was able to down-regulate the lipid transporters cluster of differentiation 36 (CD36) and Niemann-Pick C1 Like 1 (NPC1L1), increase the antioxidant superoxide dismutase gene expression, and decrease the proinflammatory cytokines, tumor necrosis factor alpha (TNFα) and interleukin 1 beta (IL-1β). Impairment of hepatic gluconeogenesis and insulin resistance in HFD rats was restored by C5 through down-regulation of the gluconeogenic genes phosphoenolpyruvate carboxykinase (PEPCK) and glucose-6-phosphatase (G6Pase), and the activation of AMP-dependent kinase serine (AMPK) and serine/threonine protein kinase B (Akt). Collectively, this novel C5 may be a therapeutic option for treating dyslipidemia, hepatic steatosis, and reducing potential risk for diabetes mellitus.

Effect of genetic polymorphisms in SREBF-SCAP pathway on therapeutic response to rosuvastatin in Saudi metabolic syndrome patients

AIM

Genetic variants contribute to statins' therapeutic variability. SREBF-SCAP pathway is a key player in lipid homeostasis. Hence, effect of SREBF-SCAP polymorphisms on therapeutic response was studied.

PATIENTS & METHODS

Metabolic syndrome patients of either sex were prescribed rosuvastatin 10 mg for 24 weeks. Clinical, anthropometric and lipid measurements were done before and after treatment. Genotyping was done by pyrosequencing.

RESULTS & CONCLUSION

No associations of SCAP and SREBF-1a genotypes with baseline lipids but significant associations with lipid reductions were observed. Significant effect of SCAP (GG; B = -8.16, p = 0.001); SREBF-1a (GG; B = -7.47, p = 0.001) and SREBF-1a (-delG; B = -7.42, p = 0.001) was observed on total cholesterol reduction. Additive trend was found between SCAP genotypes and lipid reductions. A total of 88% responders have SCAP 'G' allele (p = 0.001). Patients carrying SCAP (GG) and SREBF-1a (GG and -delG) have 9.5-, 8.6- and 14.6-times more likelihood of being responders (p < 0.05). 'G' allele in SCAP and SREBF-1a is significant predictor of rosuvastatin response.

Effect of an SNP in SCAP gene on lipid-lowering response to rosuvastatin in Indian patients with metabolic syndrome

AIM

Statins treat dyslipidemia associated with metabolic syndrome. Genetic factors contribute to variable response. Sterol regulatory element-binding factors cleavage-activating protein (SCAP) pathway regulates lipid homeostasis, so effect of SNP in SCAP gene on rosuvastatin response was studied.

MATERIALS & METHODS

Metabolic syndrome patients with low-density lipoprotein-cholesterol ≥130 mg/dl, were prescribed rosuvastatin 5 mg for 3 months. Lipids were measured initially and finally, and genotyping done.

RESULTS & CONCLUSION

Sixty-three patients completed the study. Twenty-three were homozygous for AA while 40 were heterozygous. Significant association was found between post-treatment lipid values and SCAP genotypes but not with baseline values. Cholesterol (p = 0.002) and low-density lipoprotein-cholesterol (p = 0.008) were significantly reduced in patients carrying G allele as compared with AA. There was a significant effect of G allele on cholesterol reduction (p = 0.043). Out of total responders (achieving >23.58% total cholesterol reduction), 80.5% were 2386G carriers (GG+GA) and only 19.5% were homozygous for A allele (p = 0.0048). SCAP 2386A>G gene polymorphism is a significant predictor of hypolipidemic response.

Lipid-lowering efficacy of atorvastatin

BACKGROUND

This represents the first update of this review, which was published in 2012. Atorvastatin is one of the most widely prescribed drugs and the most widely prescribed statin in the world. It is therefore important to know the dose-related magnitude of effect of atorvastatin on blood lipids.

OBJECTIVES

Primary objective To quantify the effects of various doses of atorvastatin on serum total cholesterol, low-density lipoprotein (LDL)-cholesterol, high-density lipoprotein (HDL)-cholesterol and triglycerides in individuals with and without evidence of cardiovascular disease. The primary focus of this review was determination of the mean per cent change from baseline of LDL-cholesterol. Secondary objectives • To quantify the variability of effects of various doses of atorvastatin.• To quantify withdrawals due to adverse effects (WDAEs) in placebo-controlled randomised controlled trials (RCTs).

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (Issue 11, 2013), MEDLINE (1966 to December Week 2 2013), EMBASE (1980 to December Week 2 2013), Web of Science (1899 to December Week 2 2013) and BIOSIS Previews (1969 to December Week 2 2013). We applied no language restrictions.

SELECTION CRITERIA

Randomised controlled and uncontrolled before-and-after trials evaluating the dose response of different fixed doses of atorvastatin on blood lipids over a duration of three to 12 weeks.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed eligibility criteria for studies to be included and extracted data. We collected information on withdrawals due to adverse effects from placebo-controlled trials.

MAIN RESULTS

In this update, we found an additional 42 trials and added them to the original 254 studies. The update consists of 296 trials that evaluated dose-related efficacy of atorvastatin in 38,817 participants. Included are 242 before-and-after trials and 54 placebo-controlled RCTs. Log dose-response data from both trial designs revealed linear dose-related effects on blood total cholesterol, LDL-cholesterol, HDL-cholesterol and triglycerides. The Summary of findings table 1 documents the effect of atorvastatin on LDL-cholesterol over the dose range of 10 to 80 mg/d, which is the range for which this systematic review acquired the greatest quantity of data. Over this range, blood LDL-cholesterol is decreased by 37.1% to 51.7% (Summary of findings table 1). The slope of dose-related effects on cholesterol and LDL-cholesterol was similar for atorvastatin and rosuvastatin, but rosuvastatin is about three-fold more potent. Subgroup analyses suggested that the atorvastatin effect was greater in females than in males and was greater in non-familial than in familial hypercholesterolaemia. Risk of bias for the outcome of withdrawals due to adverse effects (WDAEs) was high, but the mostly unclear risk of bias was judged unlikely to affect lipid measurements. Withdrawals due to adverse effects were not statistically significantly different between atorvastatin and placebo groups in these short-term trials (risk ratio 0.98, 95% confidence interval 0.68 to 1.40).

AUTHORS' CONCLUSIONS

This update resulted in no change to the main conclusions of the review but significantly increases the strength of the evidence. Studies show that atorvastatin decreases blood total cholesterol and LDL-cholesterol in a linear dose-related manner over the commonly prescribed dose range. New findings include that atorvastatin is more than three-fold less potent than rosuvastatin, and that the cholesterol-lowering effects of atorvastatin are greater in females than in males and greater in non-familial than in familial hypercholesterolaemia. This review update does not provide a good estimate of the incidence of harms associated with atorvastatin because included trials were of short duration and adverse effects were not reported in 37% of placebo-controlled trials.

Simvastatin induced neurite outgrowth unveils role of cell surface cholesterol and acetyl CoA carboxylase in SH-SY5Y cells

Statins are known to modulate cell surface cholesterol (CSC) and AMP-activated protein kinase (AMPK) in non-neural cells; however no study demonstrates whether CSC and AMPK may regulate simvastatin induced neuritogenesis (SIN). We found that simvastatin (SIM) maintains CSC as shown by Fillipin III staining, Flotillin-2 protein expression / localization and phosphorylation of various receptor tyrosine kinases (RTKs) in the plasma membrane. Modulation of CSC revealed that SIN is critically dependent on this CSC. Simultaneously, phospho array for mitogen activated protein kinases (MAPKs) revealed PI3K / Akt as intracellular pathway which modulates lipid pathway by inhibiting AMPK activation. Though, SIM led to a transient increase in AMPK phosphorylation followed by a sudden decline; the effect was independent of PI3K. Strikingly, AMPK phosphorylation was regulated by protein phosphatase 2A (PP2A) activity which was enhanced upon SIM treatment as evidenced by increase in threonine phosphorylation. Moreover, it was observed that addition of AMP analogue and PP2A inhibitor inhibited SIN. Bio-composition of neurites shows that lipids form a major part of neurites and AMPK is known to regulate lipid metabolism majorly through acetyl CoA carboxylase (ACC). AMPK activity is negative regulator of ACC activity and we found that phosphorylation of ACC started to decrease after 6 hrs which becomes more pronounced at 12 hrs. Addition of ACC inhibitor showed that SIN is dependent on ACC activity. Simultaneously, addition of Fatty acid synthase (FAS) inhibitor confirmed that endogenous lipid pathway is important for SIN. We further investigated SREBP-1 pathway activation which controls ACC and FAS at transcriptional level. However, SIM did not affect SREBP-1 processing and transcription of its target genes likes ACC1 and FAS. In conclusion, this study highlights a distinct role of CSC and ACC in SIN which might have implication in process of neuronal differentiation induced by other agents.

Lipid lowering efficacy of atorvastatin

BACKGROUND

Atorvastatin is one of the most widely prescribed drugs and the most widely prescribed statin in the world. It is therefore important to know the dose-related magnitude of effect of atorvastatin on blood lipids.

OBJECTIVES

To quantify the dose-related effects of atorvastatin on blood lipids and withdrawals due to adverse effects (WDAE).

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) on The Cochrane Library Issue 4, 2011, MEDLINE (1966 to November 2011), EMBASE (1980 to November 2011), ISI Web of Science (1899 to November 2011) and BIOSIS Previews (1969 to November 2011). No language restrictions were applied.

SELECTION CRITERIA

Randomised controlled and uncontrolled before-and-after trials evaluating the dose response of different fixed doses of atorvastatin on blood lipids over a duration of 3 to 12 weeks.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trial quality and extracted data. WDAE information was collected from the placebo-controlled trials.

MAIN RESULTS

Two hundred fifty-four trials evaluated the dose-related efficacy of atorvastatin in 33,505 participants. Log dose-response data revealed linear dose-related effects on blood total cholesterol, low-density lipoprotein (LDL)-cholesterol and triglycerides. Combining all the trials using the generic inverse variance fixed-effect model for doses of 10 to 80 mg/day resulted in decreases of 36% to 53% for LDL-cholesterol. There was no significant dose-related effects of atorvastatin on blood high-density lipoprotein (HDL)-cholesterol. WDAE were not statistically different between atorvastatin and placebo for these short-term trials (risk ratio 0.99; 95% confidence interval 0.68 to 1.45).

AUTHORS' CONCLUSIONS

Blood total cholesterol, LDL-cholesterol and triglyceride lowering effect of atorvastatin was dependent on dose. Log dose-response data was linear over the commonly prescribed dose range. Manufacturer-recommended atorvastatin doses of 10 to 80 mg/day resulted in 36% to 53% decreases of LDL-cholesterol. The review did not provide a good estimate of the incidence of harms associated with atorvastatin because of the short duration of the trials and the lack of reporting of adverse effects in 37% of the placebo-controlled trials.

Atorvastatin modulates the DDAH1/ADMA system in high-fat diet-induced insulin-resistant rats with endothelial dysfunction

Dimethylarginine dimethyl-aminohydrolase 1 (DDAH1) is a metabolic enzyme for asymmetric dimethylarginine (ADMA), both of which are closely related to endothelial function. Endothelial dysfunction, a main risk factor of cardiovascular diseases, can be attributed to insulin resistance. We aimed to determine the effects of atorvastatin, an endothelium-protective drug, on DDAH1/ADMA in insulin-resistant rats. Insulin resistance in male Sprague-Dawley rats was induced with a high-fat diet for 8 weeks. Some rats received atorvastatin (30 mg/kg/day) for an additional 8 weeks. Insulin-resistant rats exhibited not only decreases in the DDAH activity and aortic expression of DDAH1 and sterol regulatory element-binding protein 1 (SREBP1) but also increases in plasma ADMA levels, all of which were inhibited by atorvastatin. Insulin sensitivity and DDAH activity showed a significant positive correlation. In conclusion, our results suggest that atorvastatin may modulate DDAH1/ADMA to improve endothelial function in insulin-resistant rats; SREBP1 may also play a role in this.

Differentially expressed genes in human peripheral blood as potential markers for statin response

There is a considerable inter-individual variation in response to statin therapy and one third of patients do not meet their treatment goals. We aimed to identify differentially expressed genes that might be involved in the effects of statin treatment and to suggest potential markers to guide statin therapy. Forty-six healthy Korean subjects received atorvastatin; their whole-genome expression profiles in peripheral blood were analyzed before and after atorvastatin administration in relation with changes in lipid profiles. The expression patterns of the differentially expressed genes were also compared with the data of familial hypercholesterolemia (FH) patients and controls. Pairwise comparison analyses revealed differentially expressed genes involved in diverse biological processes and molecular functions related with immune responses. Atorvastain mainly affected antigen binding, immune or inflammatory response including interleukin pathways. Similar expression patterns of the genes were observed in patients with FH and controls. The Charcol-Leyden crystal (CLC), CCR2, CX3CR1, LRRN3, FOS, LDLR, HLA-DRB1, ERMN, and TCN1 genes were significantly associated with cholesterol levels or statin response. Interestingly, the CLC gene, which was significantly altered by atorvastatin administration and differentially expressed between FH patients and controls, showed much bigger change in high-responsive group than in low-responsive group. We identified differentially expressed genes that might be involved in mechanisms underlying the known pleiotropic effects of atorvastatin, baseline cholesterol levels, and drug response. Our findings suggest CLC as a new candidate marker for statin response, and further validation is needed.

Membrane lipid defects are responsible for the generation of reactive oxygen species in peripheral blood mononuclear cells from vitiligo patients

The pathogenesis of vitiligo, an acquired depigmenting disease of the skin, involves oxidative stress. Based on that, the generation of reactive oxygen species (ROS) by the mitochondria may be relevant in the pathogenesis of vitiligo. Here, we evaluate the biochemical and functional alterations involved in the defective activity that has been previously described both in melanocytes and peripheral blood mononuclear cells (PBMC) from vitiligo patients. Moreover, we used a freeze-thaw test as a mild stress stimulus to disclose any latent defects in the assembly of membrane lipids that may compromise the functionality of the membrane itself. We show that the lipid constitution of the membrane is altered in vitiligo. Specifically, the cardiolipin (CL) level in the mitochondrial inner membrane is reduced and the level of cholesterol is increased. Furthermore, an increase in the expression level of 3-hydroxy-3methyl-glutaryl-CoenzymeA-reductase (HMG-CoA reductase), the rate-limiting enzyme for cholesterol biosynthesis, was also seen. Associated with that, the expression of electron transport chain (ETC) lipid-dependent subunits was also modified, and their expression was further affected by the freeze-thaw stress. The expression of CL-independent mitochondrial proteins, such as porin and Bcl2, were unaffected in vitiligo PBMC. These data confirm that ETC protein expression mainly correlates with lipid arrangement and that loss of their expression is not due to generalized or random oxidative-mediated damage. We suggest that the modification of membrane lipid components in vitiligo cells may be the biochemical basis for the mitochondrial impairment and the subsequent production of intracellular ROS following the exposure to a mild stress.

Statin regulation of CYP3A4 and CYP3A5 expression

CYP3A4 and CYP3A5 are cytochrome P450 enzymes that are highly expressed in the liver and gut and metabolize endogenous compounds and xenobiotics. Statins are cholesterol-lowering drugs that are extensively metabolized by CYP3A4 and CYP3A5. The bioavailability of statins is affected by CYP3A4 and CYP3A5 and glucuronidases metabolism as well as uptake and efflux transporters that affect drug disposition. CYP3A4 and CYP3A5 variants have been demonstrated to influence the pharmacokinetics, efficacy and safety of statins. Inducers and inhibitors of CYP3A4 and CYP3A5 play an important role in reducing statin efficacy and increase the risk of adverse effects, respectively. Statins have been demonstrated to increase CYP3A expression in vitro, most likely because they are ligands to nuclear receptors (pregnane X receptor and constitutive androsterone receptor) that form heterodimers with retinoid X receptors and bind to responsive elements in the CYP3A4 and CYP3A5 promoter regions. This special report outlines the earlier studies on variability of response to statins owing to CYP3A variants and highlights findings on the induction of CYP3A4 and CYP3A5 expression by statins.

ABCA1 expression and statins: inhibitory effect in peripheral blood mononuclear cells

The ATP-binding cassette transporter A1 (ABCA1) has an essential role in the formation of nascent high-density lipoprotein particles and also participates in the cholesterol efflux from macrophages in the artery wall. Several substances, such as statins, or even gene variants are able to modulate ABCA1 expression. There is strong evidence that statin treatment downregulates the ABCA1 expression in nonloaded macrophages. Interestingly, in cholesterol-loaded macrophages, which are more relevant to atherogenesis, this effect is lost. We observed an inhibitory effect of atorvastatin in peripheral blood mononuclear cells of hypercholesterolemic individuals. Moreover, in these individuals, the ABCA1 -14C>T polymorphism was associated with high baseline gene-expression levels. Other studies are needed to evaluate how relevant these findings are to the formation of arterial foam cells in vivo.