Interethnic Differences in Drug Response: The Contribution of Genetic Variability in β Adrenergic Receptor and Cytochrome P4502C9

Drug-microbiota interactions: an emerging priority for precision medicine

Individual variability in drug response (IVDR) can be a major cause of adverse drug reactions (ADRs) and prolonged therapy, resulting in a substantial health and economic burden. Despite extensive research in pharmacogenomics regarding the impact of individual genetic background on pharmacokinetics (PK) and pharmacodynamics (PD), genetic diversity explains only a limited proportion of IVDR. The role of gut microbiota, also known as the second genome, and its metabolites in modulating therapeutic outcomes in human diseases have been highlighted by recent studies. Consequently, the burgeoning field of pharmacomicrobiomics aims to explore the correlation between microbiota variation and IVDR or ADRs. This review presents an up-to-date overview of the intricate interactions between gut microbiota and classical therapeutic agents for human systemic diseases, including cancer, cardiovascular diseases (CVDs), endocrine diseases, and others. We summarise how microbiota, directly and indirectly, modify the absorption, distribution, metabolism, and excretion (ADME) of drugs. Conversely, drugs can also modulate the composition and function of gut microbiota, leading to changes in microbial metabolism and immune response. We also discuss the practical challenges, strategies, and opportunities in this field, emphasizing the critical need to develop an innovative approach to multi-omics, integrate various data types, including human and microbiota genomic data, as well as translate lab data into clinical practice. To sum up, pharmacomicrobiomics represents a promising avenue to address IVDR and improve patient outcomes, and further research in this field is imperative to unlock its full potential for precision medicine.

Practical recommendations for the use of beta-blockers in chronic obstructive pulmonary disease

INTRODUCTION

Controversies regarding the use of beta-blocker in chronic obstructive pulmonary disease (COPD) have been longstanding and based on inconsistent data. COPD and cardiovascular disease have many shared risk factors and potentially overlapping pathophysiologic mechanisms. Beta-blockers, a mainstay of treatment in ischemic heart disease, congestive heart failure, and cardiac arrhythmia, remain underutilized in COPD patients despite considerable evidence of safety. Furthermore, observational studies indicated the potential benefits of beta-blockers in COPD via a variety of possible mechanisms. Recently, a randomized controlled trial of metoprolol versus placebo failed to show a reduction in COPD exacerbation risk in subjects with moderate to severe COPD and no absolute indication for beta-blocker use.

AREAS COVERED

Physiology of beta-adrenergic receptors, links between COPD and cardiovascular disease, and the role of beta-blockers in COPD management are discussed.

EXPERT COMMENTARY

Beta-blockers should not be used to treat COPD patients who do not have conditions with clear guideline-directed recommendations for their use. Vigilance is recommended in prescribing these medications for indications where another drug class could be utilized.

Predictors of plasma polychlorinated biphenyl concentrations among reproductive-aged black women

Polychlorinated biphenyls (PCBs) are a class of lipophilic endocrine-disrupting chemicals with wide industrial use in the U.S. from the 1930s through 1977. Due to their environmental and biological persistence, low levels of PCBs remain detected in wildlife and humans. Although U.S. studies have shown higher serum PCB concentrations among Black women compared with White women, studies of correlates of PCB exposure among Black women are scarce. We examined predictors of plasma PCB concentrations in a cross-sectional analysis of baseline data from a prospective cohort study of 1693 premenopausal Black women aged 23-35 years from Detroit, Michigan (2010-2012). We collected demographic, behavioral, dietary, and medical data via self-administered questionnaires, telephone interviews, and in-person clinic visits, as well as non-fasting blood samples. We measured concentrations of 24 PCB congeners in baseline plasma from a subset of 762 participants. We used linear regression for log-transformed lipid-adjusted PCB concentrations to calculate percentage differences across levels of selected predictors. We did this separately for individual PCBs, sum of total PCBs, and sum of PCBs by degree of chlorination and hormonal activity. PCB concentrations were positively associated with age, duration of urban residence, cigarette smoking, heavy alcohol intake, and being breastfed in infancy, and inversely associated with body mass index (BMI) and lactation duration. The strength of some associations varied by degree of chlorination. For example, a 5-kg/m² higher BMI corresponded to a 2.9% lower summed concentration of tri- and tetra-substituted PCBs (95% CI -4.6%, -1.2%), an 8.3% lower summed concentration of penta- and hexa-substituted PCBs (95% CI -10.0%, -6.5%), and a 12.1% lower summed concentration of hepta-, octa-, nona-, and deca-substituted PCBs (95% CI -13.7%, -10.4%). Likewise, associations for age and being breastfed in infancy were stronger for higher-chlorinated PCBs. Results agree with studies on predictors of PCB body burdens, few of which include large numbers of Black women.

Cardiovascular Pharmacogenomics: Does It Matter If You're Black or White?

Race and ancestry have long been associated with differential risk and outcomes to disease as well as responses to medications. These differences in drug response are multifactorial with some portion associated with genomic variation. The field of pharmacogenomics aims to predict drug response in patients prior to medication administration and to uncover the biological underpinnings of drug response. The field of human genetics has long recognized that genetic variation differs in frequency between ancestral populations, with some single nucleotide polymorphisms found solely in one population. Thus far, most pharmacogenomic studies have focused on individuals of European and East Asian ancestry, resulting in a substantial disparity in the clinical utility of genetic prediction for drug response in US minority populations. In this review, we discuss the genetic factors that underlie variability to drug response and known pharmacogenomic associations and how these differ between populations, with an emphasis on the current knowledge in cardiovascular pharmacogenomics.

Impact of the β-1 adrenergic receptor polymorphism on tolerability and efficacy of bisoprolol therapy in Korean heart failure patients: association between β adrenergic receptor polymorphism and bisoprolol therapy in heart failure (ABBA) study

BACKGROUND/AIMS

We evaluated the association between coding region variants of adrenergic receptor genes and therapeutic effect in patients with congestive heart failure (CHF).

METHODS

One hundred patients with stable CHF (left ventricular ejection fraction [LVEF] < 45%) were enrolled. Enrolled patients started 1.25 mg bisoprolol treatment once daily, then up-titrated to the maximally tolerable dose, at which they were treated for 1 year.

RESULTS

Genotypic analysis was carried out, but the results were blinded to the investigators throughout the study period. At position 389 of the β-1 adrenergic receptor gene (ADRB1), the observed minor Gly allele frequency (Gly389Arg + Gly389Gly) was 0.21, and no deviation from Hardy-Weinberg equilibrium was observed in the genotypic distribution of Arg389Gly (p = 0.75). Heart rate was reduced from 80.8 ± 14.3 to 70.0 ± 15.0 beats per minute (p < 0.0001). There was no significant difference in final heart rate across genotypes. However, the Arg389Arg genotype group required significantly more bisoprolol compared to the Gly389X (Gly389Arg + Gly389Gly) group (5.26 ± 2.62 mg vs. 3.96 ± 2.05 mg, p = 0.022). There were no significant differences in LVEF changes or remodeling between two groups. Also, changes in exercise capacity and brain natriuretic peptide level were not significant. However, interestingly, there was a two-fold higher rate of readmission (21.2% vs. 10.0%, p = 0.162) and one CHF-related death in the Arg389Arg group.

CONCLUSIONS

The ADRB1 Gly389X genotype showed greater response to bisoprolol than the Arg389Arg genotype, suggesting the potential of individually tailoring β-blocker therapy according to genotype.

Pharmacogenetics of nicotine addiction: role of dopamine

The neurotransmitter dopamine (DA) plays a central role in addictive disorders, including nicotine addiction. Specific DA-related gene variants have been studied to identify responsiveness to treatment for nicotine addiction. Genetic variants in DRD2, DRD4, ANKK1, DAT1, COMT and DBH genes show some promise in informing personalized prescribing of smoking cessation pharmacotherapies. However, many trials studying these variants had small samples, used retrospective design or were composed of mainly self-identified Caucasian individuals. Furthermore, many of these studies lacked a comprehensive measurement of nicotine metabolism rate, did not assess the roles of sex or the menstrual cycle, and did not investigate the role of rare variants and/or epigenetic factors. Future work should be conducted addressing these limitations to more effectively utilize DA genetic information to unlock the potential of smoking cessation pharmacogenetics.

Race, ethnicity, ancestry, and pharmacogenetics

Pharmacogenetics is the study of how genetic variation influences the response to drugs. The concepts of race, ethnicity, and ancestry have long had a strong influence on pharmacogenetic discovery and on our understanding of population-level differences in drug response. The primary goal of pharmacogenetics, however, is to identify the individual genetic determinants of drug activity so that therapy can be tailored to the individual patient. This article describes the relationship between the concepts of race, ethnicity, and ancestry and how these concepts have been applied to pharmacogenetics, and it provides examples of the benefits and pitfalls associated with the use of racial or ethnic labels in genetic studies. The future of pharmacogenetics, including the study of rare genetic variation and what this means for racial or ethnic disparities in pharmacogenetic discovery, is also discussed.

Fish ingestion and congener specific polychlorinated biphenyl and p,p'-dichlorodiphenyldichloroethylene serum concentrations in a great lakes cohort of pregnant African American women

A cohort of low income, city dwelling, pregnant African American Women (delivered from 1994-1999) was assembled to identify factors related to organochlorine exposure through consumption of Great Lakes resources. The cohort is known as the Great Lakes Cohort of Pregnant African American Women (GLCPAAW). Pregnant women from metropolitan Chicago, IL area clinics were administered a questionnaire on diet, demographics, and health history. Weight, height, and serum lipids were measured at delivery along with serum organochlorines such as PCBs and DDE. Congener specific concentrations of PCBs and p,p'-DDE found in the maternal serum are reported. Dominant PCB congeners found in the serum of the pregnant women at delivery included PCB 101, 118, 138, 153, and 180. The high prevalence and magnitude of PCB 101 (greater than the limit of detection in >80% of the women in the cohort) are unique characteristics of this cohort. Great Lakes fish has been identified as a source of exposure to organochlorines in several studies. Spearman correlations and robust regression models were utilized to identify the impact of Great Lakes fish ingestion on cohort serum organochlorine concentrations. Several potential confounders of the relationship between serum organochlorines and Great Lakes fish consumption were identified. Covariates related to organochlorines in correlations as well as regression models included age, body surface area, fish ingestion, lipids, parity, race and smoking. Lower chlorinated PCB congeners do not follow the same trends as the higher chlorinated congeners and DDE. The higher chlorinated PCB congeners (PCB 138, 153, and 180) and DDE were correlated with age while the lower chlorinated congeners were not. PCB 153 and 180 regression models included age as a significant covariate. None of the higher chlorinated congeners correlated to race, while both lower chlorinated congeners were correlated to race. Race was also significant in both lower chlorinated congeners' regression models. PCB 101, a lower chlorinated congener seldom found in human serum, is readily found in the cohort. Airborne PCB exposure as well as diminished metabolism of PCB 101 in African Americans may explain the increased presence of PCB 101 and it's correlation with race. High end sport fish consumers (> or =1 meal per week) carried elevated levels of DDE and higher chlorinated PCB congeners (138, 153, and 180) compared to non-sport fish eaters. Unexpectedly, DDE was correlated more consistently with fish ingestion and age (a marker of bioaccumulation) in comparison to PCBs. Small correlations were found between serum PCBs and fish ingestion (Spearman correlation=0.19 for total PCBs and fish meals per year). Additionally, Serum PCBs in low end Great Lakes sport fish consumers were not higher than non-consumers. These findings suggest the women of the cohort are being exposed to PCBs through other routes in addition to Great lakes sport fish. One major route of exposure may be Chicago air. The observed trends amongst individual PCB congeners has important ramifications because lower chlorinated congeners or their metabolites may be mediators of toxicity. Organochlorine exposure through Great Lakes fish ingestion was clearly identified in high end fish consumers while associations with race, metabolism, and possible airborne exposures pose new questions.

Pharmacogenetics and obstetric anesthesia

The ultimate goal of pharmacogenetics research is to help doctors tailor doses of medicines to a person's unique genetic make-up, making medicines safer and more effective for everyone. Although there still are no guidelines and immediate clinical implications for practitioners providing analgesia or anesthesia, it is essential to realize that trial-and-error pharmacotherapy and one-size-fits-all dogmas are bound to die. This review briefly outlines the genetic variability of pharmacokinetics and pharmacodynamics and discusses selected fields relevant to obstetric anesthesiologists for whom the challenges of translating pharmacogenetics to clinical practice hopefully are on their way.