Pharmacogenomics of oral antidiabetic medications: current data and pharmacoepigenomic perspective

Genetic diversity of cytochrome P450 in patients receiving psychiatric care in Greece: a step towards clinical implementation

Aim: We herein inferred the genetic diversity of CYP450 isoenzymes to predict the percentage of patients who need dose adjustment in drugs used in psychiatry.Materials & methods: Data of 784 Greek patients receiving psychiatric care who were genotyped for CYP2D6, CYP2C19, CYP1A2, CYP3A5 and CYP2C9 isoenzymes were inferred to gene-drug pairs according to the US FDA, Clinical Pharmacogenetics Implementation Consortium and Dutch Pharmacogenetics Working Group annotations and published literature.Results: Atypical metabolism was found for 36.8% of patients in CYP2D6, 49.2% in CYP2C19, 45% in CYP1A2, 16.7% in CYP3A5 and 41.8% in CYP2C9. Dosage adjustment need was estimated for 10.2% of venlafaxine, 10.0% of paroxetine, 6.4% of sertraline, 30.8% of citalopram, 52.1% of escitalopram, 18.2% of fluvoxamine, 54.1% of tricyclic antidepressants, 16.7% of zuclopenthixol, 10.6% of haloperidol and 13.3% of risperidone treated patients.Conclusion: Clinical psychiatric pharmacogenomic implementation holds promise to improve drug effectiveness and safety.

Insulin resistance and Metabolic dysfunction-associated steatotic liver disease (MASLD): Pathways of action of hypoglycemic agents

Metabolic dysfunction-associated steatotic liver disease (MASLD) is characterized by overweight/obesity, and the presence of type 2 diabetes mellitus is the most important criterion. We propose an independent disease perspective without exclusion criteria and with less heterogeneity and greater impact because, according to the National Health and Nutrition Survey (ENSANUT), in Mexico, 25 % of adults over 60 years of age suffer from diabetes, and 96 % of those over 50 years of age have abdominal obesity. Due to the impact of insulin resistance in the pathophysiology of MASLD, which results in damage to hepatocytes, this work aims to provide an overview of the action pathways of hypoglycemic agents such as glucagon-like-1 receptor agonist and peroxisome proliferator-activated receptor-gamma agonists, whose importance lies in the fact that they are currently undergoing phase 2 studies, as well as dipeptidyl peptidase 4 inhibitors and sodium-glucose co-transporter type 2 inhibitors, which are undergoing phase 1 study trials.

Demethylation of miR-299-5p by aerobic exercise relieves insulin resistance in the vascular endothelium by repressing resistin

AIMS

Insulin resistance (IR) is a critical marker underlying type 2 diabetes mellitus (T2DM). Exercise is reported to prevent IR, yet the mechanism of which is complicated and largely unknown. Here, the study aimed to ascertain whether and how aerobic exercise mediates IR in T2DM.

METHODS

An in vivo model of high-fat diet (HFD)-induced IR and an in vitro model of high-glucose-induced IR were constructed.

RESULTS

Aerobic exercise training in mice led to attenuation of IR in the vascular endothelium. microRNA-299-5p (miR-299-5p) expression was deficient in T2MD, which could be restored by aerobic exercise through modulating the DNA methylation modification enzymes. The expression of miR-299-5p enhanced by aerobic exercise consequently resulted in ameliorating the IR in vivo. Furthermore, increased levels of nitric oxide (NO), reduced levels of Angiotensin II (Ang II), vascular endothelial growth factor (VEGF), tumor necrosis factor alpha (TNF-α), and interleukin-6 (IL-6) in response to miR-299-5p elevation suggested the anti-IR role of miR-299-5p in IR-cell model. Dual-luciferase reporter and ChIP assays identified that miR-299-5p could bind to resistin and hence repressed the resistin level.

CONCLUSION

The key observation of the study is that aerobic exercise stimulates miR-299-5p-targeted resistin inhibition through demethylation, which underlies the mechanism of reducing IR.

SLCO1B1 c.521T>C gene polymorphism decreases hypoglycemia risk in sulfonylurea-treated type 2 diabetic patients

OBJECTIVES

Pharmacogenomics can explain some of the heterogeneity of sulfonylurea (SU)-related hypoglycemia risk. Recently, a role of OATP1B1, encoded by SLCO1B1 gene, on SU liver transport prior of metabolism has been uncovered. The aim of the present study was to explore the potential association of SLCO1B1 c.521T>C polymorphism, leading to reduced OATP1B1 function, with SU-related hypoglycemia risk.

METHODS

Study cohort consists of 176 type 2 diabetes patients treated with the SUs glimepiride or gliclazide. 92 patients reported SU-related hypoglycemia, while 84 patients had never experienced a hypoglycemic event. Patients were previously genotyped for CYP2C9 *2 and *3 variant alleles that lead to decreased enzyme activity of the SU metabolizing enzyme CYP2C9 and have been associated with increased SU-related hypoglycemia risk. SLCO1B1 c.521T>C polymorphism was genotyped by use of PCR-RFLP analysis.

RESULTS

SLCO1B1 c.521TC genotype frequency was significantly lower in hypoglycemic cases than non-hypoglycemic controls (15.2% vs. 32.1%, p=0.008). In an adjusted model, c.521TC genotype significantly reduced the risk of hypoglycemia (OR 0.371; 95% C.I. 0.167-0.822; p=0.015). In CYP2C9 intermediate metabolizers (n=54) c.521TC genotype frequency was significantly decreased in cases compared to controls (3 out of 36 cases, 8.3% vs. 7 out of 18 controls, 38.9%, p=0.012). A similar albeit not significant difference of SLCO1B1 c.521TC genotype was present in CYP2C9 extensive metabolizers (n=120) (18.2% in cases vs. 30.8% in controls, p=0.113).

CONCLUSIONS

We have found a protective effect of SLCO1B1 c.521C variant on SU-related hypoglycemia risk both independently and in interaction with CYP2C9 phenotypes. Our results suggest a possible linkage of SLCO1B1 c.521T>C polymorphism with variants in other genes impairing OATPs expressed in pancreatic islets that could interfere with SU tissue distribution.

The revolution of pharmaco-omics: ready to open new avenues in materializing precision medicine?

Tweetable abstract

The pharmaco-omics revolution has started and, as a wild stream, sooner or later, will expand and dramatically improve drug discovery and individual response to pharmacotherapy. Hopefully, we will all be ready to follow the stream.

Pharmacogenomics of sulfonylureas in type 2 diabetes mellitus; a systematic review

Purpose

Genetic factors have a role in response to a target medication (personalized medicine). This study aimed to review available evidence about the relationship between gene variants and therapeutic response to sulfonylureas in type 2 diabetes, systematically.

Methods

An extensive search was done in Scopus, PubMed, and Web of Science with specific search strategy in the field from the beginning until the 1st of Jan. 2021. After sending records to endnote software and removing duplicate records remained documents were screened by title and abstract. Full texts of remained documents were assessed after removing un-related records. Required data was extracted from remained documents and records were categorized according to gene/SNP studied.

Results

Finally, 26 studies with 9170 T2DM patients with a mean age of 59.47 ± 6.67 (49.7-75.2 years) remained. The most contribution was from China, Slovakia and Greece, respectively and the most genes studied were CYP2C9, KCNJ11, and both KCNQ1 and ABCC8 with 10, 7, and 4 articles, respectively. Also, rs1799853 and rs1057910 (each with seven studies), rs5219 with six studies and CYP2C9*1(with four articles), respectively were the most common variants investigated. Studies about each gene obtained different positive or negative results and were not consistent.

Conclusion

Considering heterogeneity between SFUs pharmacogenomic studies regarding the method, sample size, population, gene/variant studied, and outcome and findings, these studies are not conclusive and need further studies.

Epigenetic Modifications and Non-Coding RNA in Diabetes-Mellitus-Induced Coronary Artery Disease: Pathophysiological Link and New Therapeutic Frontiers

Diabetes mellitus (DM) is a glucose metabolism disorder characterized by chronic hyperglycemia resulting from a deficit of insulin production and/or action. DM affects more than 1 in 10 adults, and it is associated with an increased risk of cardiovascular morbidity and mortality. Cardiovascular disease (CVD) accounts for two thirds of the overall deaths in diabetic patients, with coronary artery disease (CAD) and ischemic cardiomyopathy as the main contributors. Hyperglycemic damage on vascular endothelial cells leading to endothelial dysfunction represents the main initiating factor in the pathogenesis of diabetic vascular complications; however, the underlying pathophysiological mechanisms are still not entirely understood. This review addresses the current knowledge on the pathophysiological links between DM and CAD with a focus on the role of epigenetic modifications, including DNA methylation, histone modifications and noncoding RNA control. Increased knowledge of epigenetic mechanisms has contributed to the development of new pharmacological treatments ("epidrugs") with epigenetic targets, although these approaches present several challenges. Specific epigenetic biomarkers may also be used to predict or detect the development and progression of diabetes complications. Further studies on diabetes and CAD epigenetics are needed in order to identify possible new therapeutic targets and advance personalized medicine with the prediction of individual drug responses and minimization of adverse effects.

TCF7L2 rs7903146 C>T gene polymorphism is not associated with hypoglycemia in sulfonylurea-treated type 2 diabetic patients

Objectives

Hypoglycemia is the most common adverse effect of sulfonylureas (SUs) and a major concern when using these drugs. Transcription factor 7-like 2 (TCF7L2) rs7903146 C>T polymorphism is an established and well characterized genetic marker of type 2 diabetes (T2DM) risk. The aim of the present study was to analyze the potential association of TCF7L2 rs7903146 C>T polymorphism with SU-induced hypoglycemia in a well characterized cohort of SU-treated patients previously genotyped for cytochrome P450 2C9 (CYP2C9) and P450 oxidoreductase (POR).

Methods

The study group consisted of 176 SU-treated T2DM patients of whom 92 had experienced at least one drug-associated hypoglycemic event. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used for TCF7L2 rs7903146 genotyping.

Results

TCF7L2 rs7903146 C>T genotype and allele frequency did not differ between cases and controls (p=0.745 and 0.671, respectively). In logistic regression analysis adjusted for other factors affecting hypoglycemia, including CYP2C9 and POR genotypes, TCF7L2 rs7903146 C>T polymorphism did not increase the risk of hypoglycemia (OR=1.238, 95% C.I.=0.750–2.044, p=0.405).

Conclusions

TCF7L2 rs7903146 C>T polymorphism is not associated with SU-induced hypoglycemia. Identifying additional gene polymorphisms associated with SU-induced hypoglycemia is crucial for improving T2DM patient therapy with SUs.

TCF7L2 rs7903146 C>T gene polymorphism is not associated with hypoglycemia in sulfonylurea-treated type 2 diabetic patients

OBJECTIVES

Hypoglycemia is the most common adverse effect of sulfonylureas (SUs) and a major concern when using these drugs. Transcription factor 7-like 2 (TCF7L2) rs7903146 C>T polymorphism is an established and well characterized genetic marker of type 2 diabetes (T2DM) risk. The aim of the present study was to analyze the potential association of TCF7L2 rs7903146 C>T polymorphism with SU-induced hypoglycemia in a well characterized cohort of SU-treated patients previously genotyped for cytochrome P450 2C9 (CYP2C9) and P450 oxidoreductase (POR).

METHODS

The study group consisted of 176 SU-treated T2DM patients of whom 92 had experienced at least one drug-associated hypoglycemic event. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) was used for TCF7L2 rs7903146 genotyping.

RESULTS

TCF7L2 rs7903146 C>T genotype and allele frequency did not differ between cases and controls (p=0.745 and 0.671, respectively). In logistic regression analysis adjusted for other factors affecting hypoglycemia, including CYP2C9 and POR genotypes, TCF7L2 rs7903146 C>T polymorphism did not increase the risk of hypoglycemia (OR=1.238, 95% C.I.=0.750-2.044, p=0.405).

CONCLUSIONS

TCF7L2 rs7903146 C>T polymorphism is not associated with SU-induced hypoglycemia. Identifying additional gene polymorphisms associated with SU-induced hypoglycemia is crucial for improving T2DM patient therapy with SUs.

A Pilot Study towards the Impact of Type 2 Diabetes on the Expression and Activities of Drug Metabolizing Enzymes and Transporters in Human Duodenum

To characterize effects of type 2 diabetes (T2D) on mRNA expression levels for 10 Cytochromes P450 (CYP450s), two carboxylesterases, and three drug transporters (ABCB1, ABCG2, SLCO2B1) in human duodenal biopsies. To compare drug metabolizing enzyme activities of four CYP450 isoenzymes in duodenal biopsies from patients with or without T2D. mRNA levels were quantified (RT-qPCR) in human duodenal biopsies obtained from patients with (n = 20) or without (n = 16) T2D undergoing a scheduled gastro-intestinal endoscopy. CYP450 activities were determined following incubation of biopsy homogenates with probe substrates for CYP2B6 (bupropion), CYP2C9 (tolbutamide), CYP2J2 (ebastine), and CYP3A4/5 (midazolam). Covariables related to inflammation, T2D, demographic, and genetics were investigated. T2D had no major effects on mRNA levels of all enzymes and transporters assessed. Formation rates of metabolites (pmoles mg protein⁻¹ min⁻¹) determined by LC-MS/MS for CYP2C9 (0.48 ± 0.26 vs. 0.41 ± 0.12), CYP2J2 (2.16 ± 1.70 vs. 1.69 ± 0.93), and CYP3A (5.25 ± 3.72 vs. 5.02 ± 4.76) were not different between biopsies obtained from individuals with or without T2D (p > 0.05). No CYP2B6 specific activity was measured. TNF-α levels were higher in T2D patients but did not correlate with any changes in mRNA expression levels for drug metabolizing enzymes or transporters in the duodenum. T2D did not modulate expression or activity of tested drug metabolizing enzymes and transporters in the human duodenum. Previously reported changes in drug oral clearances in patients with T2D could be due to a tissue-specific disease modulation occurring in the liver and/or in other parts of the intestines.

Use of 4β-Hydroxycholesterol Plasma Concentrations as an Endogenous Biomarker of CYP3A Activity: Clinical Validation in Individuals With Type 2 Diabetes

The relevance of endogenous 4β-hydroxycholesterol (4β-OHC) plasma concentrations or of the 4β-OHC/total cholesterol concentration ratio (4β-OHC ratio) as surrogate markers of cytochrome P450 3A (CYP3A) activity was evaluated in individuals with (n = 38) or without (n = 35) type 2 diabetes (T2D). Midazolam was used as a comparator to validate exploratory measures of phenotypic CYP3A activity. Metabolic ratios of orally administered midazolam in nondiabetic and diabetic populations correlated significantly with 4β-OHC (r_s  = 0.64 and 0.48; P ≤ 0.003) and 4β-OHC ratio (r_s  = 0.69 and 0.46; P ≤ 0.003), respectively. Activity of CYP3A was lower in the T2D population compared with nondiabetic subjects; this decrease was reflected in 4β-OHC concentrations (24.33 vs. 12.58 ng/mL; P < 0.0001) and 4β-OHC ratio (0.13 vs. 0.09 (× 10⁴ ); P < 0.0002). These results suggest that 4β-OHC should be considered as a valid, convenient, and easy to use endogenous biomarker of CYP3A activity in patients.

Early life adversity blunts responses to pioglitazone in depressed, overweight adults

PURPOSE

Early life adversity is associated with both metabolic impairment and depression in adulthood, as well as with poorer responses to antidepressant medications. It is not yet known whether individual differences in sensitivity to antidiabetic medications could also be related to early life adversity. We examined whether a history of early life adversity affected the observed changes in metabolic function and depressive symptoms in a randomized trial of pioglitazone for augmentation of standard treatments for depression.

PURPOSE

Early life adversity is associated with both metabolic impairment and depression in adulthood, as well as with poorer responses to antidepressant medications. It is not yet known whether individual differences in sensitivity to antidiabetic medications could also be related to early life adversity. We examined whether a history of early life adversity affected the observed changes in metabolic function and depressive symptoms in a randomized trial of pioglitazone for augmentation of standard treatments for depression.

FINDINGS

We found that early life adversity significantly impaired the metabolic response to pioglitazone. Effects on depressive symptoms did not reach significance, but nonetheless suggested that pioglitazone could mitigate the depressant effects of childhood adversity, only among those insulin resistant at baseline.

CONCLUSIONS

We conclude that a history of early life adversity may impair the body's ability to respond to insulin sensitizing pharmacotherapy, and furthermore that its contribution to resistant depression may function in part via the generation of an insulin resistant phenotype.

Implication of critical pharmacokinetic gene variants on therapeutic response to metformin in Type 2 diabetes

Aim: Metformin, an oral hypoglycemic drug is the first line of treatment for Type 2 diabetes individuals. We studied the effect of critical gene single nucleotide polymorphisms  on the glucose lowering effect of metformin. Method: We performed a prospective study on 221 newly diagnosed, treatment-naive Type 2 diabetes subjects. Individuals were started with metformin monotherapy and followed up for 12 weeks. Results: Our association analysis revealed that SLC22A2 rs316019 and SLC47A2 rs12943590 were significantly associated with metformin drug response across co-dominant and dominant models, respectively. SLC22A2 rs316019 GG and SLC47A2 rs12943590 GA combined genotypes showed maximum average change in HbA1c level. Conclusion: The present study proposes a role of SLC22A2 rs316019 and SLC47A2 rs12943590 in the pharmacokinetic action of metformin.

From Homer and Hippocrates to modern personalized medicine: is there a role for pharmacoepigenomics in the treatment of alcohol addiction?

From the earliest times to the present, alcohol has evolved as part of life and culture. For most adults, moderate alcohol use is harmless, however, it lies at one end of a range that moves through alcohol abuse to alcohol addiction. Alcohol addiction is a serious and chronic psychiatric disorder that, on top of its heavy consequences on health, also brings significant social and economic losses to individuals and society at large. Pharmacotherapy of alcohol addiction exists, but its effectiveness varies significantly among individuals. Genomic and nongenomic factors are significant contributors to interindividual variation in the clinical presentation of alcohol problems and the response to a given treatment. In addition, emerging evidence suggests pharmacoepigenomics of alcohol addiction as a novel promising area for improvement of alcohol addiction management.

Pharmacogenomics in IVF: A New Era in the Concept of Personalized Medicine

Pharmacogenomics is a promising approach in the field of individualized medicine in in vitro fertilization (IVF) treatment that aims to develop optimized pharmacotherapy depending on the genetic background of each infertile woman, thus to ensure maximum effectiveness of the medication used, with minimal side effects. The unique genetic information of each infertile woman, in combination with already known, as well as new predictors of ovarian response and the progress of pharmacoepigenomics, is anticipated to greatly benefit the process of controlled ovarian stimulation. This review analyses current data on IVF pharmacogenomics, a new approach that is gradually moving to the frontline of modern IVF treatment.

Meta-analysis of association between TCF7L2 polymorphism rs7903146 and type 2 diabetes mellitus

BACKGROUND

Large scale association studies have found a significant association between type 2 diabetes mellitus (T2DM) and transcription factor 7-like 2 (TCF7L2) polymorphism rs7903146. However, the quality of data varies greatly, as the studies report inconsistent results in different populations. Hence, we perform this meta-analysis to give a more convincing result.

METHODS

The articles, published from January 1st, 2000 to April 1st, 2017, were identified by searching in PubMed and Google Scholar. A total of 56628 participants (34232 cases and 22396 controls) were included in the meta-analysis. A total of 28 studies were divided into 4 subgroups: Caucasian (10 studies), East Asian (5 studies), South Asian (5 studies) and Others (8 studies). All the data analyses were analyzed by the R package meta.

RESULTS

The significant association was observed by using the dominant model (OR = 1.41, CI = 1.36 - 1.47, p < 0.0001), recessive model (OR = 1.58, CI = 1.48 - 1.69, p < 0.0001), additive model(CT vs CC) (OR = 1.34, CI = 1.28-1.39, p < 0.0001), additive model(TT vs CC) (OR = 1.81, CI = 1.69-1.94, p < 0.0001)and allele model (OR = 1.35, CI = 1.31-1.39, p < 0.0001).

CONCLUSION

The meta-analysis suggested that rs7903146 was significantly associated with T2DM in Caucasian, East Asian, South Asian and other ethnicities.

Evaluating the impact of type 2 diabetes mellitus on CYP450 metabolic activities: protocol for a case-control pharmacokinetic study

INTRODUCTION

Diabetes affects more than 9% of the adult population worldwide. Patients with type 2 diabetes mellitus (T2DM) show variable responses to some drugs which may be due, in part, to variability in the functional activity of drug-metabolising enzymes including cytochromes P450 (CYP450s). CYP450 is a superfamily of enzymes responsible for xenobiotic metabolism. Knowledge must be gained on the impact of T2DM and related inflammatory processes on drug metabolism and its consequences on drug response. The aim of this study is to characterise the activity of CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4/5 in T2DM versus non-T2DM subjects following the administration of a cocktail of probe drug substrates.

METHODS AND ANALYSIS

This single-centre clinical study proposes the first detailed characterisation of T2DM impacts on major CYP450 drug-metabolising enzyme activities. We intend to recruit 42 patients with controlled T2DM (A1C≤7%), 42 patients with uncontrolled T2DM (A1C>7%) and 42 non-diabetic control subjects. The primary objective is to determine and compare major CYP450 activities in patients with T2DM versus non-diabetic subjects by dosing in plasma and urine probe drug substrates and metabolites following the oral administration of a drug cocktail: caffeine (CYP1A2), bupropion (CYP2B6), tolbutamide (CYP2C9), omeprazole (CYP2C19), dextromethorphan (CYP2D6), chlorzoxazone (CYP2E1) and midazolam (CYP3A4/5). Secondary objectives will evaluate the influence of variables such as glycaemia, insulinaemia, genetic polymorphisms and inflammation. The value of an endogenous biomarker of CYP3A activity is also evaluated. The first patient was recruited in May 2015 and patients will be enrolled up to completion of study groups.

ETHICS AND DISSEMINATION

Approval was obtained from the ethic review board of the CHUM research centre (Montreal, Canada).

TRIAL REGISTRATION NUMBER

NCT02291666.

Pharmacogenomics of CYP2C9: Functional and Clinical Considerations

CYP2C9 is the most abundant CYP2C subfamily enzyme in human liver and the most important contributor from this subfamily to drug metabolism. Polymorphisms resulting in decreased enzyme activity are common in the CYP2C9 gene and this, combined with narrow therapeutic indices for several key drug substrates, results in some important issues relating to drug safety and efficacy. CYP2C9 substrate selectivity is detailed and, based on crystal structures for the enzyme, we describe how CYP2C9 catalyzes these reactions. Factors relevant to clinical response to CYP2C9 substrates including inhibition, induction and genetic polymorphism are discussed in detail. In particular, we consider the issue of ethnic variation in pattern and frequency of genetic polymorphisms and clinical implications. Warfarin is the most well studied CYP2C9 substrate; recent work on use of dosing algorithms that include CYP2C9 genotype to improve patient safety during initiation of warfarin dosing are reviewed and prospects for their clinical implementation considered. Finally, we discuss a novel approach to cataloging the functional capabilities of rare 'variants of uncertain significance', which are increasingly detected as more exome and genome sequencing of diverse populations is conducted.

Effects of functional CYP2C8,CYP2C9,CYP3A5,and ABCB1 genetic variants on the pharmacokinetics of insulin sensitizer pioglitazone in Chinese Han individuals

BACKGROUND AND OBJECTIVES

Pioglitazone is a thiazolidinedione antihyperglycemic drug with insulin-sensitizing properties. We investigated whether the variant genotypes of cytochrome P450 2C8 (CYP2C8), CYP2C9, CYP3A5 and transporter ABCB1 influence the pharmacokinetic phenotype of the substrate pioglitazone in Chinese individuals.

PARTICIPANTS AND METHODS

Single-nucleotide polymorphisms were determined by the PCR-restriction fragment length polymorphism method in 244 (CYP2C8 and CYP2C9) healthy Chinese Han individuals. After a single oral dose of 30 mg pioglitazone, the plasma concentrations of the parent drug and of two major active metabolites M-III and M-IV were measured using a validated LC-MS/MS in 21 (genotyping CYP3A5 and ABCB1) of these 244 volunteers.

RESULTS

The results confirmed that the unique frequencies of CYP2C8*2 (0.0%), CYP2C8*3 (0.0%), and CYP2C9*2 (0.0%) alleles were significantly different from those reported in Whites and Africans, and there were only 10 variant CYP2C9*1/*3 heterozygous (CYP2C9*3 carriers) among 244 Chinese individuals. These results were similar to those reported in Asian ethnic populations, including the Chinese. Unexpectedly, the pioglitazone AUC0-48 in CYP2C9*3 carriers was lower (50.8%), whereas the AUC0-48 ratios of metabolites M-III/pioglitazone and M-IV/pioglitazone increased to 134.3 and 155.8%, respectively, compared with the wild-type CYP2C9*1/*1 homozygous. Moreover, this phenomenon was not observed in individuals with genetic variants of CYP3A5*3 and ABCB1 (C1236T).

CONCLUSION

The present research suggests that the CYP2C8, CYP3A5, and ABCB1 genes play no significant role in the interindividual variation of pioglitazone pharmacokinetics, whereas CYP2C9*3 carriers are likely to accelerate the metabolism of this antidiabetic drug in the Chinese Han ethnic population.

Tissue Specific Modulation of cyp2c and cyp3a mRNA Levels and Activities by Diet-Induced Obesity in Mice: The Impact of Type 2 Diabetes on Drug Metabolizing Enzymes in Liver and Extra-Hepatic Tissues

Various diseases such as type 2 diabetes (T2D) may alter drug clearance. The objective of this study was to evaluate the effects of T2D on CYP450 expressions and activities using high-fat diet (HFD) as a model of obesity-dependent diabetes in C57BL6 mice. The cyp450 mRNA expression levels for 15 different isoforms were determined in the liver and extra-hepatic tissues (kidneys, lungs and heart) of HFD-treated animals (n = 45). Modulation of cyp450 metabolic activities by HFD was assessed using eight known substrates for specific human ortholog CYP450 isoforms: in vitro incubations were conducted with liver and extra-hepatic microsomes. Expression levels of cyp3a11 and cyp3a25 mRNA were decreased in the liver (>2-14-fold) and kidneys (>2-fold) of HFD groups which correlated with a significant reduction in midazolam metabolism (by 21- and 5-fold in hepatic and kidney microsomes, respectively, p < 0.001). HFD was associated with decreased activities of cyp2b and cyp2c subfamilies in all organs tested except in the kidneys (for tolbutamide). Other cyp450 hepatic activities were minimally or not affected by HFD. Taken together, our data suggest that substrate-dependent and tissue-dependent modulation of cyp450 metabolic capacities by early phases of T2D are observed, which could modulate drug disposition and pharmacological effects in various tissues.

Targeting endothelial metaflammation to counteract diabesity cardiovascular risk: Current and perspective therapeutic options

The association of obesity and diabetes, termed "diabesity", defines a combination of primarily metabolic disorders with insulin resistance as the underlying common pathophysiology. Cardiovascular disorders associated with diabesity represent the leading cause of morbidity and mortality in the Western world. This makes diabesity, with its rising impacts on both health and economics, one of the most challenging biomedical and social threats of present century. The emerging comprehension of the genes whose alteration confers inter-individual differences on risk factors for diabetes or obesity, together with the potential role of genetically determined variants on mechanisms controlling responsiveness, effectiveness and safety of anti-diabetic therapy underlines the need of additional knowledge on molecular mechanisms involved in the pathophysiology of diabesity. Endothelial cell dysfunction, resulting from the unbalanced production of endothelial-derived vascular mediators, is known to be present at the earliest stages of insulin resistance and obesity, and may precede the clinical diagnosis of diabetes by several years. Once considered as a mere consequence of metabolic abnormalities, it is now clear that endothelial dysfunctional activity may play a pivotal role in the progression of diabesity. In the vicious circle where vascular defects and metabolic disturbances worsen and reinforce each other, a low-grade, chronic, and 'cold' inflammation (metaflammation) has been suggested to serve as the pathophysiological link that binds endothelial and metabolic dysfunctions. In this paradigm, it is important to consider how traditional antidiabetic treatments (specifically addressing metabolic dysregulation) may directly impact on inflammatory processes or cardiovascular function. Indeed, not all drugs currently available to treat diabetes possess the same anti-inflammatory potential, or target endothelial cell function equally. Perspective strategies pointing at reducing metaflammation or directly addressing endothelial dysfunction may disclose beneficial consequences on metabolic regulation. This review focuses on existing and potential new approaches ameliorating endothelial dysfunction and vascular inflammation in the context of diabesity.

Possible approaches to CYP2C9-guided prescription of sulfonylureas in Russia

AIM

To evaluate a possible role of CYP2C9 genotyping for sulfonylureas (SUs) prescription in Russia.

MATERIALS & METHODS

We have collected the current data on correlation between SUs pharmacodynamics and CYP2C9 polymorphisms. We have evaluated the frequency of CYP2C9 polymorphisms in Russia by reviewing the literature published from 2004 to 2015 on Russian CYP2C9.

RESULTS

The genotype *1/*1, which confers risk for treatment failure, has a higher frequency (81.92%) in the non-Caucasians than that (64.92%) in the Caucasians. The Caucasians have a frequency (3.58%) of the poor metabolizers (*2/*2, *2/*3 and *3/*3) eight-times higher than that (0.44%) in the non-Caucasians, predisposing an increased risk of hypoglycemia.

CONCLUSION

Considering the received data and the existed knowledge on CYP2C9 influence on SUs pharmacokinetics and pharmacodynamics, we propose a possible approach to CYP2C9-guided SUs prescription for Russians.

The Application of Genomics in Diabetes: Barriers to Discovery and Implementation

The emerging availability of genomic and electronic health data in large populations is a powerful tool for research that has drawn interest in bringing precision medicine to diabetes. In this article, we discuss the potential application of genomics to the prediction, prevention, and treatment of diabetes, and we use examples from other areas of medicine to illustrate some of the challenges involved in conducting genomics research in human populations and implementing findings in practice. At this time, a major barrier to the application of genomics in diabetes care is the lack of actionable genomic findings. Whether genomic information should be used in clinical practice requires a framework for evaluating the validity and clinical utility of this approach, an improved integration of genomic data into electronic health records, and the clinical decision support and educational resources for clinicians to use these data. Efforts to identify optimal approaches in all of these domains are in progress and may help to bring diabetes into the era of genomic medicine.

Glucose Tolerance, MTHFR C677T and NOS3 G894T Polymorphisms, and Global DNA Methylation in Mixed Ancestry African Individuals

The aim of this study is to quantify global DNA methylation and investigate the relationship with diabetes status and polymorphisms in MTHFR C677T and NOS3 G894T genes in mixed ancestry subjects from South Africa. Global DNA methylation was measured, and MTHFR rs1801133 and NOS3 rs1799983 polymorphisms were genotyped using high throughput real-time polymerase chain reaction and direct DNA sequencing. Of the 564 participants, 158 (28%) individuals had T2DM of which 97 (17.2%) were screen-detected cases. Another 119 (21.1%) had prediabetes, that is, impaired fasting glucose, impaired glucose tolerance, or the combination of both, and the remainder 287 (50.9%) had normal glucose tolerance. Global DNA methylation was significantly higher in prediabetes and screen-detected diabetes than in normal glucose tolerance (both p ≤ 0.033) and in screen-detected diabetes compared to known diabetes on treatment (p = 0.019). There was no difference in global DNA methylation between known diabetes on treatment and normal glucose tolerance (p > 0.999). In multivariable linear regression analysis, only NOS3 was associated with increasing global DNA methylation (β = 0.943; 95% CI: 0.286 to 1.560). The association of global DNA methylation with screen-detected diabetes but not treated diabetes suggests that glucose control agents to some extent may be reversing DNA methylation. The association between NOS3 rs1799983 polymorphisms and DNA methylation suggests gene-epigenetic mechanisms through which vascular diabetes complications develop despite adequate metabolic control.

Towards a genotype-based approach for a patient-centered pharmacologic therapy of type 2 diabetes

The recent data reported by Tang and colleagues in Science Translational Medicine suggest that alpha-2 adrenoceptors (α2AAR) genetic heterogeneity may explain diverging results regarding the effects of α2AAR antagonists on insulin secretion and glucose control in patients with type 2 diabetes. They first confirmed that the risk variant for rs553668 (the A allele for a single-nucleotide polymorphism in ADRA2A) is likely to cause defective insulin secretion in human pancreatic islets. Second they showed that blocking α2AAR with yohimbine dose-dependently improves the reduced insulin secretion during an oral glucose tolerance test in patients with the risk variant. The successful translation of genomic information into clinical intervention in patients with type 2 diabetes provides proof of concept for the feasibility of individualized treatment based on genotype.

Personalized medicine and type 2 diabetes: lesson from epigenetics

Similarly to genetic polymorphisms, epigenetic modifications may alter transcriptional activity and contribute to different traits of the Type 2 diabetes phenotype. The establishment of these epigenetic marks may precede diabetes onset and predict the disease. Current evidence now indicates that epigenetic differences represent markers of diabetes risk. Studies on epigenome plasticity revealed that cytokines and other metabolites, by affecting DNA methylation, may acutely reprogram gene expression and contribute to the Type 2 diabetes phenotype even in the adult life. The available evidence further indicates that epigenetic marks across the genome are subject to dynamic variations in response to environmental cues. Finally, different genes responsible for the interindividual variability in antidiabetic drug response are subjected to epigenetic regulation. Determining how specific epigenetic profiles determine diabetes is a challenging task. In the near future, the identification of epigenetic marks predictive of diabetes risk or response to treatment may offer unanticipated opportunities to personalize Type 2 diabetes management.

Allele and genotype frequency of a genetic variant in ataxia telangiectasia mutated gene affecting glycemic response to metformin in South Indian population

Allele and genotype frequency of a genetic variant in ATM gene affecting glycemic response to metformin in South Indian population.

CONTEXT

The novel polymorphism in ATM gene (rs11212617), which is implicated to have association with metformin response, exhibits inter-ethnic variability in the allele and genotype frequency distribution.

AIMS AND DESIGN

The objective of the present study is to establish the allele and genotype frequency of rs11212617 single nucleotide polymorphism in ATM gene, in South Indian population and to find if this variant has any role in the etiology of type 2 diabetes mellitus.

MATERIALS AND METHODS

The study was performed in 2 cohorts of populations, 112 healthy volunteers and 118 type 2 diabetes mellitus patients. Genomic deoxyribonucleic acid (DNA) was extracted from peripheral blood leucocytes by phenol-chloroform method and genotyping was performed by real-time polymerase chain reaction using TaqMan assay.

RESULTS

In South Indian population, the frequency of major A allele was 0.65 and the minor C allele was 0.35. AA and CC are the homozygous genotypes with frequency of 0.39 and 0.09 respectively. The frequency of heterozygous genotype AC (0.52) was found to be higher than the homozygotes. There was no significant difference in the frequency distribution in the diabetic population, which implies that this variant does not have any causative role in the disease etiology. The frequency distributions were found to be significantly different from the distributions in other ethnic populations such as Caucasians, Chinese, Japanese and Africans. But there was no significant difference when compared with the Gujarati Indians of Houston.

CONCLUSION

The frequency distribution of this novel variant in South Indian population forms a framework for further gene disease association studies to establish the association of this variant with metformin response. Our study could not find any association of this variant with respect to the disease etiology.

Genetics of type 2 diabetes: insights into the pathogenesis and its clinical application

With rapidly increasing prevalence, diabetes has become one of the major causes of mortality worldwide. According to the latest studies, genetic information makes substantial contributions towards the prediction of diabetes risk and individualized antidiabetic treatment. To date, approximately 70 susceptibility genes have been identified as being associated with type 2 diabetes (T2D) at a genome-wide significant level (P < 5 × 10⁻⁸). However, all the genetic loci identified so far account for only about 10% of the overall heritability of T2D. In addition, how these novel susceptibility loci correlate with the pathophysiology of the disease remains largely unknown. This review covers the major genetic studies on the risk of T2D based on ethnicity and briefly discusses the potential mechanisms and clinical utility of the genetic information underlying T2D.

Expression quantitative trait analyses to identify causal genetic variants for type 2 diabetes susceptibility

Type 2 diabetes (T2D) is a common metabolic disorder which is caused by multiple genetic perturbations affecting different biological pathways. Identifying genetic factors modulating the susceptibility of this complex heterogeneous metabolic phenotype in different ethnic and racial groups remains challenging. Despite recent success, the functional role of the T2D susceptibility variants implicated by genome-wide association studies (GWAS) remains largely unknown. Genetic dissection of transcript abundance or expression quantitative trait (eQTL) analysis unravels the genomic architecture of regulatory variants. Availability of eQTL information from tissues relevant for glucose homeostasis in humans opens a new avenue to prioritize GWAS-implicated variants that may be involved in triggering a causal chain of events leading to T2D. In this article, we review the progress made in the field of eQTL research and knowledge gained from those studies in understanding transcription regulatory mechanisms in human subjects. We highlight several novel approaches that can integrate eQTL analysis with multiple layers of biological information to identify ethnic-specific causal variants and gene-environment interactions relevant to T2D pathogenesis. Finally, we discuss how the eQTL analysis mediated search for “missing heritability” may lead us to novel biological and molecular mechanisms involved in susceptibility to T2D.

The pharmacogenetics of type 2 diabetes: a systematic review

OBJECTIVE

We performed a systematic review to identify which genetic variants predict response to diabetes medications.

RESEARCH DESIGN AND METHODS

We performed a search of electronic databases (PubMed, EMBASE, and Cochrane Database) and a manual search to identify original, longitudinal studies of the effect of diabetes medications on incident diabetes, HbA1c, fasting glucose, and postprandial glucose in prediabetes or type 2 diabetes by genetic variation. Two investigators reviewed titles, abstracts, and articles independently. Two investigators abstracted data sequentially and evaluated study quality independently. Quality evaluations were based on the Strengthening the Reporting of Genetic Association Studies guidelines and Human Genome Epidemiology Network guidance.

RESULTS

Of 7,279 citations, we included 34 articles (N = 10,407) evaluating metformin (n = 14), sulfonylureas (n = 4), repaglinide (n = 8), pioglitazone (n = 3), rosiglitazone (n = 4), and acarbose (n = 4). Studies were not standalone randomized controlled trials, and most evaluated patients with diabetes. Significant medication-gene interactions for glycemic outcomes included 1) metformin and the SLC22A1, SLC22A2, SLC47A1, PRKAB2, PRKAA2, PRKAA1, and STK11 loci; 2) sulfonylureas and the CYP2C9 and TCF7L2 loci; 3) repaglinide and the KCNJ11, SLC30A8, NEUROD1/BETA2, UCP2, and PAX4 loci; 4) pioglitazone and the PPARG2 and PTPRD loci; 5) rosiglitazone and the KCNQ1 and RBP4 loci; and 5) acarbose and the PPARA, HNF4A, LIPC, and PPARGC1A loci. Data were insufficient for meta-analysis.

CONCLUSIONS

We found evidence of pharmacogenetic interactions for metformin, sulfonylureas, repaglinide, thiazolidinediones, and acarbose consistent with their pharmacokinetics and pharmacodynamics. While high-quality controlled studies with prespecified analyses are still lacking, our results bring the promise of personalized medicine in diabetes one step closer to fruition.

Introduction to personalized medicine in diabetes mellitus

The world is facing an epidemic rise in diabetes mellitus (DM) incidence, which is challenging health funders, health systems, clinicians, and patients to understand and respond to a flood of research and knowledge. Evidence-based guidelines provide uniform management recommendations for "average" patients that rarely take into account individual variation in susceptibility to DM, to its complications, and responses to pharmacological and lifestyle interventions. Personalized medicine combines bioinformatics with genomic, proteomic, metabolomic, pharmacogenomic ("omics") and other new technologies to explore pathophysiology and to characterize more precisely an individual's risk for disease, as well as response to interventions. In this review we will introduce readers to personalized medicine as applied to DM, in particular the use of clinical, genetic, metabolic, and other markers of risk for DM and its chronic microvascular and macrovascular complications, as well as insights into variations in response to and tolerance of commonly used medications, dietary changes, and exercise. These advances in "omic" information and techniques also provide clues to potential pathophysiological mechanisms underlying DM and its complications.

CYP2C metabolism of oral antidiabetic drugs--impact on pharmacokinetics, drug interactions and pharmacogenetic aspects

INTRODUCTION

The cytochrome P4502C enzymes account for the metabolism of approximately 20% of therapeutic drugs including certain oral antidiabetic drugs (OADs).

AREAS COVERED

This review focuses on the effect of CYP2C enzymes on metabolism of sulphonylureas (SUs), meglitinides, and thiazolidinediones (TZDs) discussing their impact on pharmacokinetics, drug interactions and toxicological profiles. Pharmacogenetic aspects reflecting individual gene variants and variable drug effects are also considered.

EXPERT OPINION

Genetic polymorphisms of CYP2C9 enzymes (*2/*2, *2/*3, *3/*3) influence the glycaemic response to SUs and impair their substrate metabolism. Restricted data from small-sized studies with heterogenous definitions of hypoglycaemia revealed no clear association between CYP2C9 genotypes and the risk of hypoglycaemia. Functional polymorphisms of CYP2C8- and CYP2C9 drug metabolizing genes affect markedly pharmacokinetics of meglitinides. Compared to wild-type carriers, patients treated with TZDs and carrying the common CYP2C8*3 and *4 variants showed a reduced glycaemic control. The strong CYP2C8 and OATP1B1 inhibitor gemfibrozil increases substantially the plasma concentrations of repaglinide and TZDs. Numerous metabolic drug interactions exist between SUs and commonly prescribed drugs, especially anti-infectives. The complex pharmacokinetic and pharmacogenetic properties and the unfavourable short and long term risk profile of glibenclamide and glimepiride raise the question whether their use can be justified any longer.

Genotyping of CYP2C9 and VKORC1 in the Arabic population of Al-Ahsa, Saudi Arabia

Polymorphisms in the genes encoding CYP2C9 enzyme and VKORC1 reductase significantly influence the dose variability of coumarinic oral anticoagulants (COAs). Substantial inter- and intraethnic variability exists in the frequencies of CYP2C9*2 and *3 and VKORC1 -1639A alleles. However, the prevalence of CYP2C9 and VKORC1 genetic variants is less characterized in Arab populations. A total of 131 healthy adult subjects from the Al-Ahsa region of Saudi Arabia were genotyped for the CYP2C9 *2 and *3 and VKORC1 -1639G>A polymorphisms by PCR-RFLP method. The frequencies of the CYP2C9 *2 and *3 and VKORC1 -1639A alleles were 13.3%, 2.3%, and 42.4%, respectively, with no subjects carrying 2 defective alleles. The frequencies of the CYP2C9 *3 and VKORC1 -1639A alleles were significantly lower than those reported in different Arabian populations. None of the subjects with the VKORC1 -1639AA genotype were carriers of CYP2C9 *1/*3 genotypes that lead to sensitivity to COAs therapy. The low frequency of the CYP2C9 *3 allele combined with the absence of subjects carrying 2 defective CYP2C9 alleles suggests that, in this specific population, pharmacogenetic COAs dosing may mostly rely upon VKORC1 genotyping.

Cytochrome P450 enzymes in drug metabolism: regulation of gene expression, enzyme activities, and impact of genetic variation

Cytochromes P450 (CYP) are a major source of variability in drug pharmacokinetics and response. Of 57 putatively functional human CYPs only about a dozen enzymes, belonging to the CYP1, 2, and 3 families, are responsible for the biotransformation of most foreign substances including 70-80% of all drugs in clinical use. The highest expressed forms in liver are CYPs 3A4, 2C9, 2C8, 2E1, and 1A2, while 2A6, 2D6, 2B6, 2C19 and 3A5 are less abundant and CYPs 2J2, 1A1, and 1B1 are mainly expressed extrahepatically. Expression of each CYP is influenced by a unique combination of mechanisms and factors including genetic polymorphisms, induction by xenobiotics, regulation by cytokines, hormones and during disease states, as well as sex, age, and others. Multiallelic genetic polymorphisms, which strongly depend on ethnicity, play a major role for the function of CYPs 2D6, 2C19, 2C9, 2B6, 3A5 and 2A6, and lead to distinct pharmacogenetic phenotypes termed as poor, intermediate, extensive, and ultrarapid metabolizers. For these CYPs, the evidence for clinical significance regarding adverse drug reactions (ADRs), drug efficacy and dose requirement is rapidly growing. Polymorphisms in CYPs 1A1, 1A2, 2C8, 2E1, 2J2, and 3A4 are generally less predictive, but new data on CYP3A4 show that predictive variants exist and that additional variants in regulatory genes or in NADPH:cytochrome P450 oxidoreductase (POR) can have an influence. Here we review the recent progress on drug metabolism activity profiles, interindividual variability and regulation of expression, and the functional and clinical impact of genetic variation in drug metabolizing P450s.

Potential of pluripotent stem cells for diabetes therapy

Diabetes mellitus type 1 (T1DM) and type 2 (T2DM) are common diseases. To date, it is widely accepted that all forms of DM lead to the loss of beta cells. Therefore, to avoid the debilitating comorbidities when glycemic control cannot be fully achieved, some would argue that beta cell replacement is the only way to cure the disease. Due to organ donor shortage, other cell sources for beta cell replacement strategies have to be employed. Pluripotent stem cells, including embryonic stem (ES) and induced pluripotent stem (iPS) cells offer a valuable alternative to provide the necessary cells to substitute organ transplants but also to serve as a model to study the onset and progression of the disease, resulting in better treatment regimens. This review will summarize recent progress in the establishment of pluripotent stem cells, their differentiation into the pancreatic lineage with a focus on two-dimensional (2D) and three-dimensional (3D) differentiation settings, the special role of iPS cells in the analysis of genetic predispositions to diabetes, and techniques that help to move current approaches to clinical applications. Particular attention, however, is also given to the long-term challenges that have to be addressed before ES or iPS cell-based therapies will become a broadly accepted treatment option.

Association of KCNJ11 E23K gene polymorphism with hypoglycemia in sulfonylurea-treated type 2 diabetic patients

AIMS

In addition to sulfonylurea-induced severe hypoglycemia, which however is not common in T2DM patients treated solely with oral hypoglycemic drugs, mild hypoglycemia is a frequent adverse event affecting many patients treated with oral hypoglycemic drugs and has a serious impact in patient adherence to therapy and everyday clinical practice. The aim of the present study was to investigate the possible association of KCNJ11 E23K polymorphism with incidence of sulfonylurea-induced mild hypoglycemic events.

METHODS

176 T2DM patients receiving sulfonylurea were included in the study, including 92 that had experienced drug-associated hypoglycemia and 84 that had never experienced hypoglycemia while on sulfonylurea treatment. KCNJ11 E23K polymorphism was detected by use of PCR-RFLP method.

RESULTS

Frequencies of KCNJ11 E23K genotypes and alleles were not different between hypoglycemic and non-hypoglycemic T2DM patients (p=0.35 and p=0.47, respectively). In logistic regression analysis before and after adjustment for other factors known to affect this condition (age, body mass index, sulfonylurea mean daily dose, duration of T2DM, renal function and CYP2C9 genotype) KCNJ11 E23K polymorphism did not affect hypoglycemia risk.

CONCLUSIONS

KCNJ11 E23K polymorphism is not associated with increased risk of mild hypoglycemia in sulfonylurea-treated T2DM patients.

Epigenetics advancing personalized nanomedicine in cancer therapy

Personalized medicine aims to deliver the right drug to a right patient at the right time. It offers unique opportunities to integrate new technologies and concepts to disease prognosis, diagnosis and therapeutics. While selective personalized therapies are conceptually impressive, the majority of cancer therapies have dismal outcome. Such therapeutic failure could result from no response, drug resistance, disease relapse or severe side effect from improper drug delivery. Nanomedicine, the application of nanotechnology in medicine, has a potential to advance the identification of diagnostic and prognostic biomarkers and the delivery of right drug to disease sites. Epigenetic aberrations dynamically contribute to cancer pathogenesis. Given the individualized traits of epigenetic biomarkers, epigenetic considerations would significantly refine personalized nanomedicine. This review aims to dissect the interface of personalized medicine with nanomedicine and epigenetics. I will outline the progress and highlight challenges and areas that can be further explored perfecting the personalized health care.

The success of pharmacogenomics in moving genetic association studies from bench to bedside: study design and implementation of precision medicine in the post-GWAS era

Pharmacogenomics is emerging as a popular type of study for human genetics in recent years. This is primarily due to the many success stories and high potential for translation to clinical practice. In this review, the strengths and limitations of pharmacogenomics are discussed as well as the primary epidemiologic, clinical trial, and in vitro study designs implemented. A brief discussion of molecular and analytic approaches will be reviewed. Finally, several examples of bench-to-bedside clinical implementations of pharmacogenetic traits will be described. Pharmacogenomics continues to grow in popularity because of the important genetic associations identified that drive the possibility of precision medicine.