The relationships of ABCB1 3435C>T and CYP2B6 516G>T with high-density lipoprotein cholesterol in HIV-infected patients receiving Efavirenz

Effects of rifampicin, CYP2B6 and ABCB1 polymorphisms on efavirenz plasma concentration in Chinese patients living with HIV and tuberculosis

BACKGROUND

Tuberculosis (TB) is the leading opportunistic infection of people living with human immunodeficiency virus (HIV; PLWH). Cytochrome P450 (CYP) 2B6 and ATP-binding cassette sub-family B member 1 (ABCB1) are involved in the metabolism and transportation of efavirenz. The study was aimed to investigate the effects of rifampicin, CYP2B6 and ABCB1 polymorphisms on efavirenz exposure in Chinese PLWH co-infected with TB.

METHOD

PLWH were screened according to inclusion and exclusion criteria and divided into HIV group and HIV/TB group. Efavirenz plasma concentration (C₀) was determined, dose-adjusted concentration (C₀/D) was calculated, and genotypes of CYP2B6 516G>T, 785A>G, and ABCB1 2677G>T, 3435C>T were analyzed.

RESULTS

252 PLWH were enrolled, including 75 co-infected with TB and concomitant with rifampicin. Efavirenz C₀ and C₀/D were both higher in HIV group (1.94 μg/mL, 0.2007 (μg/ml)/(mg/kg/d)) compared with HIV/TB group (1.52 μg/mL, 0.1557 (μg/ml)/(mg/kg/d)) (p = .001). Efavirenz C₀/D was significantly higher in patients with variant genotypes of CYP2B6 516G>T and 785A>G (p<.001), and was significantly lower in HIV/TB group compared with HIV group among patients with CYP2B6 516 GG, TT, and 785 AA, AG genotypes (p < .05).

CONCLUSION

Efavirenz exposure is reduced by co-administration with rifampicin, and related to genetic polymorphisms of CYP2B6.

Dyslipidemia and Associated Factors in Tenofovir Disoproxil Fumarate-Based Regimen Among Human Immunodeficiency Virus-Infected Ethiopian Patients: A Hospital-Based Observational Prospective Cohort Study

Background

Studies showed conflicting results regarding the effect of broadly used tenofovir disoproxil fumarate (TDF)-based regimen on lipid profiles, and in Ethiopia, there is no data regarding the magnitude of dyslipidemia and its associated factors.

Objective

The aim of this study was to determine the magnitude of dyslipidemia and its associated factors among adult human immunodeficiency virus (HIV)-infected patients in TDF-based regimen in Tikur Anbessa Specialized Hospital (TASH) in Ethiopia.

Methods

A hospital-based observational prospective cohort study was conducted on conveniently selected 63 patients in TASH from January to September, 2019. The data was analyzed by using SPSS version 21.0, and multivariate logistic regression was used to determine associated factors with dyslipidemia.

Results

The overall dyslipidemia was 73% and 77.8% at baseline and six months, respectively. The prevalence of total cholesterol (TC) ≥200 mg/d, triglyceride (TG) ≥150 mg/dL, low density lipoprotein cholesterol (LDL-c) ≥130 mg/dL, and high density lipoprotein cholesterol (HDL-c) <40 mg/dL was 38.1% vs 42.9%, 23.8% vs 31.7%, 17.5% vs 22.2%, and 41.3% vs 41.3% at baseline and six month follow-up, respectively. Age ≥50 years old (AOR = 0.6, 95% CI: 0.004-0.71, p = 0.026) and body mass index (BMI) ≥25 kg/m² (AOR = 6.44, 95% CI: 1.34-30.9, p = 0.02) were significantly associated with TC ≥200 mg/dL. Having cancer (AOR = 0.04, 95% CI: 0.01-0.6, p = 0.019) and education level below diploma (AOR = 9.47, 95% CI: 1.15-77.96, p = 0.037) were significantly associated with overall dyslipidemia.

Conclusion

In this study, the proportion of patients with dyslipidemia was higher at six month follow-up but there was no significant difference when compared to baseline. The mean LDL-c was significantly higher at six months compared to its baseline mean. The associated factors with dyslipidemia were age, BMI, having cancer and low level of education. Lipid profile monitoring is recommended in patients with a younger age and higher BMI.

Quantile-specific heritability of high-density lipoproteins with implications for precision medicine

BACKGROUND

We have previously shown that the effect of a high-density lipoprotein (HDL) genetic risk score depends on whether the phenotype (HDL cholesterol) is high or low relative to its distribution (quantile-dependent expressivity).

OBJECTIVE

Evidence for quantile-dependent expressivity was sought using a more inclusive genetic measure (quantile-specific heritability, h²) in a larger population (Framingham cohort).

METHODS

Quantile regression was used to test whether the offspring-parent (β_OP) and full-sib (β_FS) regression slopes increased with the percentiles of the offspring's HDL distribution in 10,650 parent-offspring pairs and 2130 sibships. Quantile-specific heritability was estimated by 2β_OP/(1 + r_spouse) and [(8β_FSr_spouse + 1)^0.5-1]/(2r_spouse), where r_spouse is the spouse correlation.

RESULTS

HDL cholesterol heritability estimated from β_OP increased significantly (P = 4.2 × 10^-5) from the 10^th (h² ± SE: 0.44 ± 0.03), 25^th (0.45 ± 0.03), 50^th (0.47 ± 0.03), and 75^th (0.56 ± 0.04) to the 90^th percentiles (0.65 ± 0.06) of the offspring's age- and sex-adjusted HDL cholesterol distribution. Heritability estimated from β_FS also increased significantly with the percentiles of the offspring's HDL cholesterol (P = .002), apo A1 (P = .006), HDL2 cholesterol (P = .003), and HDL3 cholesterol distribution (P = .02). Consistent with quantile-dependent expressivity, published pharmacologic and nutritional interventions that raised (eg, statin, fibrates, estrogen replacement therapy, efavirenz, and dietary fat) or lowered HDL cholesterol concentrations (tamoxifen, dietary carbohydrate) correspondingly increased and decreased genetic effects.

CONCLUSION

HDL cholesterol heritability increased with increasing percentile of the offspring's HDL distribution. Whereas precision medicine is based on the premise that genetic markers identify patients most likely to benefit from drugs and diet, quantile-dependent expressivity postulates that the strong signals from these genetic markers simply trace the heritability increase with increasing plasma HDL concentrations. Thus, quantile-dependent expressivity provides an alternative interpretation to these genotype-specific effects.

A pharmacist’s role in the individualization of treatment of HIV patients

The pharmacological treatment of HIV is complex and varies considerably among patients, as does the response of patients to therapy, requiring treatment plans that are closely tailored to individual needs. Pharmacists can take an active role in individualizing care by employing their knowledge of pharmacokinetics and pharmacogenetics and by interacting directly with patients in counseling sessions. These strategies promote the following: maintenance of plasma concentrations of antiretroviral agents within therapeutic ranges, prediction of pharmacological response of patients with certain genetic characteristics, and clinical control of HIV through the correct use of antiretroviral treatments. Together, these strategies can be used to tailor antiretroviral therapy to individual patients, thus improving treatment efficacy and safety.

A Population Pharmacokinetic/Pharmacodynamic Model Predicts Favorable HDL Cholesterol Changes Over the First 5 Years in Children Treated With Current Efavirenz-Based Regimens

Efavirenz use is associated with changes in cholesterol concentrations, but it is unclear whether this effect is related to drug concentrations. Using efavirenz and cholesterol plasma concentrations measured in 87 antiretroviral-naive children in Thailand, we assessed indirect response models to describe the evolution of high- and low-density lipoprotein (HDL, LDL) cholesterol concentrations in relation to efavirenz plasma concentrations over time where efavirenz was assumed to either stimulate cholesterol production or inhibit its elimination. Simulations of cholesterol evolution for children with different average efavirenz concentrations (Cav ) according to their assumed status of "fast" or "slow" metabolizers of efavirenz were performed. At treatment initiation, children's median (interquartile range, IQR) age was 8 years (5 to 10), body mass index z-score 0.01 (-1.05 to 1.44), HDL 31 mg/dL (24 to 44), and LDL 83 mg/dL (69 to 100). Median (IQR) efavirenz Cav was 1.7 mg/L (1.3 to 2.1) during the period of observation. The best model describing the evolution of HDL and LDL cholesterol concentrations over time assumed that efavirenz inhibited their elimination. HDL concentrations increase over 5 years, whereas LDL concentrations increased only during the first 4 months and then returned to baseline levels afterward. Simulations predicted that, after 3 years, HDL would increase to 63 mg/dL in "fast" metabolizers and 97 mg/dL in "slow" metabolizers of efavirenz. The population pharmacokinetic-pharmacodynamic (PK-PD) model shows that favorable HDL cholesterol changes can be expected in children with current efavirenz dosing guidelines over 5 years of treatment.

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

BACKGROUND

The relation between the ABCB1 and CYP7A1 genes and serum lipid levels and lipid-lowering efficacy of statin treatment is inconsistent.

OBJECTIVE

The purpose of this meta-analysis was to explore the associations between the ABCB1 and CYP7A1 genes and serum lipid levels and lipid-lowering efficacy of statin treatment.

METHODS

MEDLINE, EMBASE, and the Cochrane Library databases were searched systematically for studies of associations between relevant single nucleotide polymorphisms C3435 T (ABCB1), G2677 A/T (ABCB1), and A-204C (CYP7A1) and serum lipid levels or statin treatment. Associations were assessed in pooled data by calculating mean difference with 95% confidence intervals.

RESULTS

Seventeen studies with 4890 patients were included in this meta-analysis. The "AA" group at A-204C (CYP7A1) had lower serum total cholesterol (TC) levels than "AC + CC" group. The "AA" group at A-204C (CYP7A1) had greater reduction in low-density lipoprotein cholesterol (LDL-C) with statin treatment than "AC + CC" group. The "GG" group at G2677 A/T (ABCB1) had less reduction in TC and LDL-C with statin treatment than "non-GG" group.

CONCLUSIONS

The A-204C (CYP7A1) polymorphism was associated with the level of TC and the lipid-lowering efficacy of statin treatment in the level of LDL-C. The G2677 A/T (ABCB1) polymorphism was associated with the lipid-lowering efficacy of statin treatment in the levels of LDL-C and TC.

Atenolol induced HDL-C change in the pharmacogenomic evaluation of antihypertensive responses (PEAR) study

We sought to identify novel pharmacogenomic markers for HDL-C response to atenolol in participants with mild to moderate hypertension. We genotyped 768 hypertensive participants from the Pharmacogenomic Evaluation of Antihypertensive Responses (PEAR) study on the Illumina HumanCVD Beadchip. During PEAR, participants were randomized to receive atenolol or hydrochlorothiazide. Blood pressure and cholesterol levels were evaluated at baseline and after treatment. This study focused on participants treated with atenolol monotherapy. Association with atenolol induced HDL-C change was evaluated in 232 whites and 152 African Americans using linear regression. No SNPs achieved a Bonferroni corrected P-value. However, we identified 13 regions with consistent association across whites and African Americans. The most interesting of these regions were seven with prior associations with HDL-C, other metabolic traits, or functional implications in the lipid pathway: GALNT2, FTO, ABCB1, LRP5, STARD3NL, ESR1, and LIPC. Examples are rs2144300 in GALNT2 in whites (P=2.29x10(-4), β=-1.85 mg/dL) and rs12595985 in FTO in African Americans (P=2.90x10(-4), β=4.52 mg/dL), both with consistent regional association (P<0.05) in the other race group. Additionally, baseline GALNT2 expression differed by rs2144300 genotype in whites (P=0.0279). In conclusion, we identified multiple gene regions associated with atenolol induced HDL-C change that were consistent across race groups, several with functional implications or prior associations with HDL-C.

Pharmacogenetic and pharmacokinetic aspects of CYP3A induction by efavirenz in HIV patients

We investigated the effects of pharmacogenetic variations and efavirenz pharmacokinetics on inter-individual differences in the extent of CYP3A induction by efavirenz using 4β-hydroxycholesterol/cholesterol (4β-OHC/Chol) as a marker for CYP3A induction. Plasma 4β-hydroxycholesterol and cholesterol concentrations were determined at baseline, and at the 4th, 16th and 48th week of efavirenz-based highly active antiretroviral therapy in antiretroviral therapy-naive HIV patients (n=77). Efavirenz plasma concentrations were quantified at weeks 4 and 16. CYP2B6, CYP3A5, ABCB1, UGT2B7 genotyping were done. Compared with baseline, the median plasma 4β-OHC/Chol ratio increased at the 4th (257%), 16th (291%) and 48th (165%) week (P<0.0001). CYP2B6*6 genotype significantly influenced 4β-OHC/Chol ratio at weeks 16 (P=0.02) and 48 (P=0.04) being highest in CYP2B6*6/*6>*1/*6>*1/*1. There were positive correlations between plasma efavirenz and 4β-OHC/Chol ratios (week 4: P=0.02, week 16: P=0.001). CYP3A enzyme induction by efavirenz is pronounced in CYP2B6 slow metabolizers who have high efavirenz plasma exposure.

Management of dyslipidemia in HIV-infected patients

Antiretroviral therapy has dramatically increased survival for HIV-infected individuals. As this population lives longer, coronary heart disease has become an important comorbid condition. Dyslipidemia in HIV-infected individuals is a complex condition, with multiple contributing factors including the HIV virus itself, individual genetic characteristics and antiretroviral therapy-induced metabolic changes. Effective management of dyslipidemia in this population is essential to reduce cardiovascular risk but presents multiple challenges due to interactions between antiretroviral therapy agents and lipid-lowering medications.

CYP2B6 polymorphism and nonnucleoside reverse transcriptase inhibitor plasma concentrations in Chinese HIV-infected patients

The purpose of this study was to investigate the frequency of CYP2B6 polymorphisms and their influence on plasma concentrations of efavirenz and nevirapine in HIV-infected Chinese patients. After written informed consent, 159 patients were enrolled at Shanghai Public Health Clinical Center. Genotyping for 516 G>T, 785 A>G, 983 T>C, and 1459 T>C polymorphisms in CYP2B6, together with CYP3A4 -392 A>G, CYP3A5 6986 A>G, and ABCB1 (2677 G>T/A, 3435 C>T), were performed. Plasma efavirenz and nevirapine concentrations of 120 patients at steady state were assessed by high-performance liquid chromatography-mass spectrometry. The minor allele frequency for CYP2B6 516 G>T, 785 A>G, 983 T>C, and 1459 T>C was 0.16, 0.24, 0, and 0, respectively; and 0.07, 0.32, 0.15, and 0.35 for CYP3A4 -392 A>G, CYP3A5 6986 A>G, ABCB1 2677 G>T/A, and ABCB1 3435 C>T, respectively. Univariate analysis indicated associations between 516 G>T (P < 0.01) with efavirenz but not nevirapine plasma concentrations. None of other genetic variants was associated with plasma efavirenz or nevirapine concentrations. Although CYP2B6 516 G>T was associated with high plasma efavirenz concentrations, such an association was not evident with nevirapine in this Chinese patient population. CYP3A4 -392 A>G, CYP3A5 6986 A>G, and ABCB1 (2677 G>T/A, 3435 C>T) had no significant impact on plasma efavirenz or nevirapine concentrations.