The role of common variants of ABCB1 and CYP7A1 genes in serum lipid levels and lipid-lowering efficacy of statin treatment: a meta-analysis

Identification of clinical and pharmacogenetic factors influencing metformin response in Type 2 diabetes mellitus

Metformin, a hypoglycemic drug for Type 2 diabetes mellitus, shows variability in pharmacokinetics and response due to membrane transporters. This study followed 34 Type 2 diabetes mellitus patients on metformin treatment. Genetic variants in 11 metformin transport-related genes were analyzed, revealing associations. Specifically, SLC47A1 rs2289669 A/A and SLC22A4 rs1050152 T/T genotypes correlated with glycated hemoglobin values at 6 months. SLC47A1 rs2289669 G/A genotype influenced glucose levels at 6 months, while SLC29A4 rs3889348 A/A, SLC47A1 rs2289669 A/A, SLC22A4 rs1050152 C/T and SLC47A2 rs12943590 A/A genotypes were linked to glucose levels at 12 months. Additionally, ABCB1 rs2032582 C/A and ABCG2 rs2231137 C/T genotypes impacted cholesterol levels at 12 months. These findings shed light on metformin response determinants, offering insights for further research.

A meta-analysis of the pooled impact of CYP7A1 single nucleotide polymorphisms on serum lipid responses to statins

Background and Aims: Various publications suggested that there is an association between CYP7A1 single nucleotide polymorphisms (SNP) and a reduced response to statin therapy, but the results were inconsistent. This study aimed to collectively review these publications to appraise the effect of statins on cholesterol control in carriers of CYP7A1 variant alleles. Methods: PUBMED, Cochrane and EMBASE were searched systematically to identify reported studies on the lipid responses to statin treatment between carriers of the variant allele versus the non-variant allele of CYP7A1 SNPs. The change from baseline in lipid responses for all included studies were calculated using weighted mean differences (WMD) (with 95% confidence interval (CI)). A meta-analysis was conducted to pool results using either the random-effects model or the fixed effects model. Results: A total of 6 publications comprising of 1,686 subjects for the assessment of total cholesterol, LDL-C and HDL-C and 1,156 subjects for the assessment of triglycerides were included in the meta-analyses. Subjects who were non-carriers of a CYP7A1 SNP (-204 A/C (rs3808607), -278 A/C (rs3808607) and rs8192875) had a greater reduction in total cholesterol (overall WMD -0.17, 95% CI -0.29, -0.06) and LDL-C levels (overall WMD -0.16, 95% CI -0.26, -0.05) as compared with subjects who borne the variant allele of CYP7A1 SNPs when administered a statin. Conclusion: The presence of variant allele of CYP7A1 SNPs may result in suboptimal control of total cholesterol and LDL-C levels as compared with individuals who do not carry the variant allele, when administered an equivalent dose of statin.

Pharmacogenomics of lipid-lowering agents: the impact on efficacy and safety

Hyperlipidemia is a significant risk factor for cardiovascular disease morbidity and mortality. The lipid-lowering drugs are considered the cornerstone of primary and secondary prevention of atherosclerotic cardiovascular disease. Unfortunately, the lack of efficacy and associated adverse effects, ranging from mild-to-moderate to potentially life-threatening, lead to therapy discontinuation. Numerous reports support the role of gene polymorphisms in drugs' pharmacokinetic parameters and their associated adverse reactions. Therefore, this study aims to understand the pharmacogenomics of lipid-lowering drugs and the impact of genetic variants of key genes on the drugs' efficacy and toxicity. Indeed, genetically guided lipid-lowering therapy enhances overall safety, improves drug adherence and achieves long-term therapy.

Type 2 Diabetes Risk and Lipid Metabolism Related to the Pleiotropic Effects of an ABCB1 Variant: A Chinese Family-Based Cohort Study

The single nucleotide polymorphism (SNP) rs4148727 in ABCB1 (encoding p-glycoprotein) is associated with lipid levels; however, its association with type 2 diabetes (T2DM) and its the genetic correlation with lipid profiles and T2DM are unclear. We included 2300 participants from 593 families. A generalized estimating equations (GEE) model and Cox regression models were used to estimate the SNP’s effects on T2DM and lipid profiles. The participation of the SNP in T2DM pathogenesis through lipid-associated pathways was tested using mediation analysis. The G allele of the SNP was related to a 32% (6–64%, p = 0.015) increase in T2DM risk. It was also associated with a 10% (1–20%, p = 0.029), 17% (3–32%, p = 0.015), and 4% (1–7%, p = 0.015) increment in total cholesterol (TC), triglyceride (TG), and apolipoprotein A (Apo-A) concentrations, respectively. According to the mediation analysis, only TG (6.9%) and Apo-B (4.0%) had slight but significant mediation effects on the total impact of the SNP on T2DM. The pleiotropic effects of the ABCB1 variant on T2DM and lipids likely act via different pathways. The biological mechanisms should be verified in a future study.

Association of Drug-Metabolizing Enzyme and Transporter Gene Polymorphisms and Lipid-Lowering Response to Statins in Thai Patients with Dyslipidemia

Purpose

Statins are increasingly widely used in the primary and secondary prevention of cardiovascular disease. However, there is an inter-individual variation in statin response among patients. The study aims to determine the association between genetic variations in drug-metabolizing enzyme and transporter (DMET) genes and lipid-lowering response to a statin in Thai patients with hyperlipidemia.

Patients and Methods

Seventy-nine patients who received statin at steady-state concentrations were recruited. Serum lipid profile was measured at baseline and repeated after 4-month on a statin regimen. The genotype profile of 1936 DMET markers was obtained using Affymetrix DMET Plus genotyping microarrays.

Results

In this DMET microarray platform, five variants; SLCO1B3 (rs4149117, rs7311358, and rs2053098), QPRT (rs13331798), and SLC10A2 (rs188096) showed a suggestive association with LDL-cholesterol-lowering response. HDL-cholesterol-lowering responses were found to be related to CYP7A1 gene variant (rs12542233). Seven variants, SLCO1B3 (rs4149117, rs7311358, and rs2053098); SULT1E1 (rs3736599 and rs3822172); and ABCB11 (rs4148768 and rs3770603), were associated with the total cholesterol-lowering response. One variant of the ABCB4 gene (rs2109505) was significantly associated with triglyceride-lowering response.

Conclusion

This pharmacogenomic study identifies new genetic variants of DMET genes that are associated with the lipid-lowering response to statins. Genetic polymorphisms in DMET genes may impact the pharmacokinetics and lipid-lowering response to statin. The validation studies confirmations are needed in future pharmacogenomic studies.

TMT-based proteomics analysis reveals the efficacy of jiangzhuo formula in improving the lipid profiles of dyslipidemia rats

ETHNOPHARMACOLOGICAL RELEVANCE

Jiangzhuo Formula (JZF) is a traditional Chinese herbal prescription that is clinically applied to treat dyslipidemia. However, the mechanism underlying its efficacy remains unexplored.

AIM OF THE STUDY

This study aims to elucidate the underlying mechanisms, explore potential pathways, and identify the key proteins of JZF for the treatment of dyslipidemia.

METHODS

In this work, Q-Orbitrap high-resolution liquid chromatography mass spectrometry was used to identify the natural ingredients in JZF, rats with dyslipidemia were established via a high-fat diet for four weeks, then the dyslipidemia rats were treated with high-dose JZF (9 g/d) and low-dose JZF (4.5 g/d) for four weeks. After treatment, serum lipid detection and Oil-red-O staining were conducted to assess the efficacy of JZF in ameliorating dyslipidemia. Tandem mass tag (TMT) -based quantitative proteomics technology was then used to evaluate the roles and importance of proteins from the extracted hepatic tissue. The differentially expressed proteins were assessed by Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, Gene Ontology (GO), and protein-protein interaction (PPI) networks. Western blot and PCR analysis were used to validate the potential targets regulated by JZF.

RESULTS

JZF could significantly improve the blood lipid profiles of serum and fat deposits of the liver. A total of 123 differentially expressed proteins were detected after JZF intervention, comprising 65 up-regulated proteins and 58 down-regulated proteins. The KEGG pathway analysis revealed that cholesterol metabolism, the PPAR signaling pathway, and bile secretion were the principal pathways involved in the disordered lipid metabolism, while GO analysis suggested that proteins that are located in the cell, regulate cellular processes, and show binding activity contribute to reductions in lipids. The combination of proteomics, Western blot, and PCR suggested that Apolipoprotein B (APOB), Apolipoprotein E (APOE), cholesterol 7 alpha-hydroxylase A1 (CYP7A1), and Hydroxymethylglutaryl-CoA synthase 1 (HMGCS1) might play critical roles in JZF's lipid-lowering network.

CONCLUSION

JZF can effectively improve lipid profiles via multiple pathways involved in cholesterol metabolism, the PPAR signaling pathway, and bile secretion. Generally, the proteomics techniques used in this research show that JZF could be a promising drug for the treatment of dyslipidemia.

Palmatine regulates bile acid cycle metabolism and maintains intestinal flora balance to maintain stable intestinal barrier

OBJECTIVE

Palmatine (PAL) is a natural isoquinoline alkaloid that has been widely used in the pharmaceutical field. The current study aimed to investigate the function of PAL in improving hyperlipidemia induced by high-fat diet (HFD) in rats.

METHODS

Biochemical analysis of triglyceride (TG), total cholesterol (TC), low-density lipoprotein-cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDLC) was performed on rats. Total bile acid (TBA) and stool TC and TBA were also measured to assess the changes in total bile acid excretion. RT-qPCR was employed to detect the expression of genes related to bile acid metabolism, and the Western blot assay was used to detect the levels of CYP7A1, ZO-1, ZO-2, and Claudin-1. The siRNA experiment was employed to further investigate whether PAL regulated CYP7A1 through PPARα. Lipopolysaccharide (LPS) and FITC-dextran (FD-4) were also tested to assess the intestinal permeability.

RESULTS

AL-treated rats had lower TC, TG, LDL-C levels, lower serum TBA levels, and increased fecal TBA and TC levels. Furthermore, CYP7A1 protein expression was up-regulated in PAL-treated rats. Additionally, PAL regulated bile acid metabolism by up-regulating the expression of CYP7A1 and PPARα and down-regulating the expression of FXR. Besides, the area of plasma FD-4 and LPS content in the PAL group were reduced, and the expression of proteins ZO-1, ZO-2 and Claudin-1 related to intestinal permeability was increased.

CONCLUSION

All in all, PAL could mediate the PPARα-CYP7A1 pathway to maintain the balance of intestinal flora, regulate the bile acid metabolism, and reduce the blood lipids of rats, thereby protecting against hyperlipidemia.

Effects of different fatty acids on BRL3A rat liver cell damage

To evaluate the effects of fatty acids on endoplasmic reticulum (ER) stress, oxidative stress, and lipid damage. We treated BRL3A rat liver cells with, linoleic (LA), linolenic, oleic (OA), palmitic (PA), palmitoleic (POA), or stearic (SA) acid for 12 hr. The characteristics of cell lipid deposition, oxidative stress indexes, ER stress markers, nuclear factor κB p65 (NF-κB p65), lipid synthesis and transport regulators, and cholesterol metabolism regulators were analyzed. Endoplasmic chaperones like glucose-regulated protein 78, CCAAT-enhancer-binding protein, NF-κB p65, hydrogen peroxide, and malonaldehyde in PA- and SA-treated cells were significantly higher than in other treated cells. Deposition of fatty acids especially LA and POA were significantly increased than in other treated cells. De novo lipogenesis regulators sterol regulatory element-binding protein 1c, fatty acid synthase, and acetyl-coenzyme A carboxylase 1 (ACC1) expression were significantly increased in all fatty acid stimulation groups, and PA- and SA-treated cells showed lower p-ACC1 expression and higher scd1 expression than other fatty acid groups. Very low-density lipoprotein synthesis and apolipoprotein B100 expression in free fatty acids treated cells were significantly lower than control. PA, SA, OA, and POA had shown significantly increased cholesterol synthesis than other treated cells. PA and SA showed the lower synthesis of cytochrome P7A1 and total bile acids than other fatty acids treated cells. Excess of saturated fatty acids led to severe ER and oxidative stress. Excess unsaturated fatty acids led to increased lipid deposition in cultured hepatocytes. A balanced fatty acid intake is needed to maintain lipid homeostasis.

Effect of Cytochrome P450 7A1 (CYP7A1) Polymorphism on Lipid Responses to Simvastatin Treatment

BACKGROUND

Identifying patients with high risk of low response to statin therapy is important for optimization of lipid-lowering therapy. Cholesterol 7α-hydroxylase, a rate-limiting enzyme encoded by cytochrome P450 7A1 (CYP7A1) gene, is considered to be associated with statin efficacy. This study aimed to investigate the association between a novel CYP7A1 single nucleotide polymorphism rs3824260 and statin treatment response for hypercholesteremic patients in Chinese Han population.

METHODS

A total of 336 subjects were prescribed with simvastatin for 12 weeks after enrollment. Plasma lipid parameters were measured at enrollment and after 12-week simvastatin treatment separately. Subjects were classified into high- and low-response groups depending on their total cholesterol, low-density lipoprotein cholesterol (LDL-C) and TG changes and increase or reduction groups according to their high-density lipoprotein cholesterol (HDL-C) levels changing after simvastatin treatment. The CYP7A1 rs3824260 was genotyped from blood samples with a SNaPshot assay.

RESULTS

At baseline, the LDL-C level and TG level were significantly higher in the AA genotype, while the HDL-C level was significantly higher in the GG genotype of CYP7A1 rs3824260. Patients carrying AA genotype are at an increased risk of low response for LDL-C reduction (odds ratio = 2.295, 95% confidence interval = 1.164-4.524, P = 0.016). Furthermore, the GG genotype of rs3824260 was significantly associated with a high risk of HDL-C reduction response after simvastatin therapy (odds ratio = 2.240, 95% confidence interval = 1.137-4.413, P = 0.025).

CONCLUSIONS

The CYP7A1 gene polymorphism rs3824260 is related to inappropriate response of simvastatin treatment for hypercholesterolemia patients in Chinese Han population.

Interactions Between ABCB1 Genotype and Preoperative Statin Use Impact Clinical Outcomes Among Breast Cancer Patients

Multiple clinical trials investigate statins' effects in breast cancer. The ABCB1 genotype appears to influence statin response and toxicity in the cardiovascular setting. This exploratory study aimed to investigate the interplay between preoperative statin use, ABCB1 genotype, and tumor-specific expression of the statin target 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) in breast cancer. Preoperative statin use, ABCB1 C3435T genotype, and HMGCR expression in relation to outcome were analyzed in 985 primary breast cancer patients from a population-based prospective cohort in Sweden from 2002 to 2012. Preoperative statin use (n = 80) was not associated with ABCB1 C3435T genotype (n = 576), HMGCR expression (n = 848), or clinical outcomes. ABCB1 C3435T TT-carriers had lower risk of breast cancer events than any C-carriers (adjusted hazard ratio (HR_adj) 0.74; 95%CI 0.49, 1.12), but only in non-statin users (P_interaction = 0.042). Statin users with TT genotype had higher risk of distant metastasis (HR_adj 4.37; 95%CI 1.20, 15.91; P_interaction = 0.009) and shorter overall survival than other patients (HR_adj 3.77; 95%CI 1.37, 10.39; P_interaction = 0.019). In conclusion, there were nominally significant interactions between ABCB1 genotype and preoperative statin use on clinical outcomes, while preoperative statin use was not associated with outcomes. Since this is an exploratory study of the impact of the ABCB1 genotype in relation to statin use and clinical outcomes in the breast cancer setting, the results should be interpreted with caution and warrant replication in an independent cohort, preferably in a randomized setting. Since statin use is common in breast cancer patients, it would be of interest to further elucidate the clinical impact of the ABCB1 genotype in breast cancer.

Interactions Between Regulatory Variants in CYP7A1 (Cholesterol 7α-Hydroxylase) Promoter and Enhancer Regions Regulate CYP7A1 Expression

BACKGROUND

CYP7A1 (cholesterol 7α-hydroxylase) catalyzes the rate-limiting step in bile acid biosynthesis from cholesterol-a main pathway for cholesterol removal from the body. CYP7A1 single-nucleotide polymorphisms (SNPs) are associated with total cholesterol and LDL (low-density lipoprotein) levels, risk of cardiovascular diseases, and other phenotypes; however, results are inconsistent, and causative variants remain uncertain, except for a frequent promoter SNP (rs3808607).

METHODS

We used chromatin conformation capture (4C assay), chromatin immunoprecipitation qPCR assay in hepatocytes, and CRISPR (clustered regularly interspaced short palindromic repeats)-mediated genome editing in hepatocellular carcinoma cell line cells to identify regulatory regions for CYP7A1. We then screened for SNPs located in regulatory regions, testing effects on reporter gene assays and on hepatic CYP7A1 expression by measuring allelic mRNA expression imbalance.

RESULTS

4C assays showed several regions interacting with CYP7A1 promoter. CRISPR-mediated genome editing in hepatocellular carcinoma cell line cells revealed a novel CYP7A1 enhancer and a repressor region, located >10 kb downstream of the CYP7A1 promoter. SNP screening with an allelic mRNA expression imbalance in human livers and reporter gene assays identified a frequent functional SNP (rs9297994) located in the downstream CYP7A1 enhancer region. SNP rs9297994 is in high linkage disequilibrium with promoter SNP rs3808607 but has opposite effects on CYP7A1 mRNA expression. Their combined effects using a 2-SNP model robustly associate with hepatic CYP7A1 mRNA expression, ranging >2 orders of magnitude. Moreover, only the 2-SNP model, but not each SNP alone, is significantly associated with LDL levels, risk of coronary artery disease, statin response, and diabetes mellitus in several clinical cohorts, including CATHGEN (Catheterization Genetics) and Framingham.

CONCLUSIONS

Two interacting regulatory SNPs modulate CYP7A1 expression and are associated with risk of coronary artery disease and diabetes mellitus.

Statins impact primary embryonic mouse neural stem cell survival, cell death, and fate through distinct mechanisms

Statins inhibit HMG-CoA reductase, the rate-limiting enzyme in the cholesterol biosynthesis pathway (CBP), and are used for the prevention of cardiovascular disease. The anti-inflammatory effects of statins may also provide therapeutic benefits and have led to their use in clinical trials for preeclampsia, a pregnancy-associated inflammatory condition, despite their current classification as category X (i.e. contraindicated during pregnancy). In the developing neocortex, products of the CBP play essential roles in proliferation and differentiation of neural stem-progenitor cells (NSPCs). To understand how statins could impact the developing brain, we studied effects of pravastatin and simvastatin on primary embryonic NSPC survival, proliferation, global transcription, and cell fate in vitro. We found that statins dose dependently decrease NSPC expansion by promoting cell death and autophagy of NSPCs progressing through the G1 phase of the cell cycle. Genome-wide transcriptome analysis demonstrates an increase in expression of CBP genes following pravastatin treatment, through activation of the SREBP2 transcription factor. Co-treatment with farnesyl pyrophosphate (FPP), a CBP metabolite downstream of HMG-CoA reductase, reduces SREBP2 activation and pravastatin-induced PARP cleavage. Finally, pravastatin and simvastatin differentially alter NSPC cell fate and mRNA expression during differentiation, through a non-CBP dependent pathway.

Genetic Variations Associated with Anti-Tuberculosis Drug-Induced Liver Injury

Purpose of this Review

In order to combat the development of drug resistance, the clinical treatment of tuberculosis requires the combined use of several anti-tuberculosis (anti-TB) drugs, including isoniazid and rifampicin. Combinational treatment approaches are suggested by the World Health Organization (WHO) and are widely accepted throughout the world. Unfortunately, a major side effect of the treatment is the development of anti-tuberculosis drug-induced liver injury (AT-DILI). Many factors contribute to isoniazid- and rifampicin-mediated AT-DILI and genetic variations are among the most common factors. The purpose of this review is to provide information on genetic variations associated with isoniazid- and rifampicin-mediated AT-DILI.

Recent Findings

The genetic variations associated with AT-DILI have been identified in the genomic regions within or near genes encoding proteins in the following pathways: drug metabolizing enzymes (NAT2, CYP2E1, and GSTs), accumulation of bile acids, lipids, and heme metabolites (CYP7A1, BSEP, UGTs, and PXR), immune adaptation (HLAs and TNF-α), and oxidant challenge (TXNRD1, SOD1, BACH1, and MAFK).

Summary

The information summarized in this review considers the genetic bases of risk factors contributing to AT-DILI and provides information that may help for future studies. Some of the implicated genetic variations can be used in the design of genetic tests and serve as biomarkers for the prediction of isoniazid- and rifampicin-mediated AT-DILI risk in personalized medicine.

Genetic determinants of inherited susceptibility to hypercholesterolemia - a comprehensive literature review

Hypercholesterolemia is a strong determinant of mortality and morbidity associated with cardiovascular diseases and a major contributor to the global disease burden. Mutations in four genes (LDLR, APOB, PCSK9 and LDLRAP1) account for the majority of cases with familial hypercholesterolemia. However, a substantial proportion of adults with hypercholesterolemia do not have a mutation in any of these four genes. This indicates the probability of having other genes with a causative or contributory role in the pathogenesis of hypercholesterolemia and suggests a polygenic inheritance of this condition. Here in, we review the recent evidence of association of the genetic variants with hypercholesterolemia and the three lipid traits; total cholesterol (TC), HDL-cholesterol (HDL-C) and LDL-cholesterol (LDL-C), their biological pathways and the associated pathogenetic mechanisms. Nearly 80 genes involved in lipid metabolism (encoding structural components of lipoproteins, lipoprotein receptors and related proteins, enzymes, lipid transporters, lipid transfer proteins, and activators or inhibitors of protein function and gene transcription) with single nucleotide variants (SNVs) that are recognized to be associated with hypercholesterolemia and serum lipid traits in genome-wide association studies and candidate gene studies were identified. In addition, genome-wide association studies in different populations have identified SNVs associated with TC, HDL-C and LDL-C in nearly 120 genes within or in the vicinity of the genes that are not known to be involved in lipid metabolism. Over 90% of the SNVs in both these groups are located outside the coding regions of the genes. These findings indicates that there might be a considerable number of unrecognized processes and mechanisms of lipid homeostasis, which when disrupted, would lead to hypercholesterolemia. Knowledge of these molecular pathways will enable the discovery of novel treatment and preventive methods as well as identify the biochemical and molecular markers for the risk prediction and early detection of this common, yet potentially debilitating condition.

ABCB1 C3435T polymorphism and the lipid-lowering response in hypercholesterolemic patients on statins: a meta-analysis

BACKGROUND

A number of researches have evaluated the association between the ABCB1 polymorphism and the lipid-lowering response of statins, but the results have been inconclusive. To examine the lipid-lowering efficacy and safety associated with the ABCB1 C3435T polymorphism in hypercholesterolemic patients receiving statin, all available studies were included in this meta-analysis.

METHODS

A systematic search for eligible studies in the Cochrane library database, Scopus and PubMed was performed. Articles meeting the inclusion criteria were comprehensively reviewed, and the available data were accumulated by the meta-analysis.

RESULTS

The results indicated that the comparisons of CC+CT vs. TT were associated with a significant elevation of the serum HDL-C levels after statin treatment (CC+CT vs. TT: MD, 2.46; 95 % CI, 0.36 to 4.55; P = 0.02), and the ABCB1 C3435T variant in homozygotes was correlated with decreases in LDL-C (CC vs. TT: MD, 2.29; 95 % CI, 0.37 to 4.20; P = 0.02) as well as TC (CC vs. TT: MD, 3.05; 95 % CI, 0.58 to 5.53; P = 0.02) in patients treated with statin. However, we did not observe a significant association in the TG group or an association between other genetic models serum lipid parameters. In addition, statin treatment more than 5 months led to a higher risk of muscle toxicity.

CONCLUSIONS

The evidence from the meta-analysis demonstrated that the ABCB1 C3435T polymorphism may represent a pharmacogenomic biomarker for predicting treatment outcomes in patients on statins and that statin treatment for more than 5 months can increase the risk of myopathy.