Genomics of cardiovascular disease

Prospects of personalized medicine in cardiovascular diseases

Cardiovascular diseases remain the dominant cause of death worldwide. In the last decades, the remarkable advances in human genetic and genomic research, plus the now common use of genome-wide association studies, have led to the identification of numerous genetic variants associated with specific cardiovascular traits and diseases. Although the clinical applications are limited because the genetic risk of common cardiovascular disease is still unexplained, and the mechanisms of action of the genetic factor(s) are not known, these research advances have, in turn, widely opened the concept of personalized medicine. In this paper, the status and prospects of personalized medicine for cardiovascular disease will be presented. This will be followed by a discussion of issues regarding the implementation of personalized medicine.

Translocator protein (18 kDa): a promising therapeutic target and diagnostic tool for cardiovascular diseases

The translocator protein (18 kDa) (TSPO) is a five transmembrane domain protein in mitochondria, abundantly expressed in a variety of organs and tissues. TSPO contributes to a wide range of biological processes, including cholesterol transportation, mitochondrial membrane potential and respiratory chain regulation, apoptosis, and oxidative stress. Recent studies have demonstrated that TSPO might also be involved in the physiological regulation of cardiac chronotropy and inotropy. Accordingly, TSPO ligands play significant roles in protecting the cardiovascular systems under pathological conditions through cardiac electrical activity retention, intracellular calcium maintenance, mitochondrial energy provision, mitochondrial membrane potential equilibrium, and reactive oxygen species inhibition. This paper focuses on the physiological and pathological characteristics of TSPO in the cardiovascular systems and also summarizes the properties of TSPO ligands. TSPO represents a potential therapeutic target and diagnostic tool for cardiovascular diseases including arrhythmia, myocardial infarction, cardiac hypertrophy, atherosclerosis, myocarditis, and large vessel vasculitis.

High fat diets and pathology in the guinea pig. Atherosclerosis or liver damage?

Animal models have been widely used to investigate the relationship between diet and atherosclerosis and also to study disease etiology and possible interventions. Guinea pigs have been suggested to be a more "realistic" model for atherosclerosis due to their many similarities to humans. However, few published studies actually reported observations of characteristic atherosclerotic lesions and even fewer of advanced lesions. Studies, by our group, of guinea pigs fed on a high-fat diet revealed similar observations, with indications primarily of fatty streaks but little evidence of atherosclerotic plaques. This review discusses the feasibility of the guinea pig as a model for dietary-induced atherosclerosis. As it stands, current evidence raises doubt as to whether guinea pigs could serve as a realistic model for atherosclerosis. However, our own data and the literature suggest that they could be useful models for studying lipoprotein metabolism, non-alcoholic fatty liver disease, and dietary interventions which may help regulate these conditions.

Gazing through the Crystal Ball of Science—Cardiovascular Disease in 2100

Recently, we had the opportunity to review the progress that has been made in the field of cardiovascular disease over the past century in The FASEB Journal and, based on those thoughts, in this article we predict what may transpire in this ‘century of biology’. Although it is true that ‘the best way to predict the future is to invent it’, we gaze through the prism of modern biomolecular science for a vision of a possible future and see cardiology practice that is transformed. In the second half of the 20th century, we developed a more fundamental understanding of atherosclerotic vascular disorders and invented life-saving therapeutics. We saw a similar development of mechanism-based pharmacotherapy to address heart failure, primarily through agents that antagonize the excessive concentration of circulating neurohumoral agents. Now we are in the midst of the device era, from stents to cardiac resynchronization therapy to transcatheter valves. The next wave of treatments will build on an increasingly sophisticated understanding of the molecular determinants of cardiovascular disorders and engineering feats that are barely perceptible now. Genomic profiling, molecular prescriptions for prevention and personalized therapeutics, regenerative medicine and the new field of cardiovascular tissue bioengineering will transform cardiovascular medicine. If the human species can survive threats of our own doing, such as the related epidemics of obesity and diabetes, by the turn of the next century, treatment of cardiovascular disease will not resemble the present in almost any way.

My road to Damascus: how I converted to the prohormone theory and the proprotein convertases

My desire as a young endocrinologist to improve my clinical skills through a better knowledge of hormone chemistry led me to serendipitous discoveries and unexpected horizons. The first discovery, published in 1967, revealed that peptide hormones are derived from endoproteolytic cleavages of larger precursor polypeptides. It was the foundation of the prohormone theory. Initially thought to apply to a few hormones, the theory rapidly extended to many proteins, including neuropeptides, neurotrophins, growth and transcription factors, receptors, extracellular matrix proteins, bacterial toxins, and viral glycoproteins. Its endoproteolytic activation mechanism has become a fundamental cellular process, affecting many biological functions. It implied the existence of specific endoproteolytic enzymes. These proprotein convertases were discovered in 1990. They have been shown to play a wide range of important roles in health and disease. They have opened up novel therapeutic avenues. Inactivation of PCSK9 to reduce plasma cholesterol is currently the most promising. To make this good thing even better, I recently discovered in a French Canadian family a potent PCSK9 (Gln152His) mutation that significantly lowers plasma cholesterol and should confer cardiovascular longevity. The discovery helped me to complete the loop: "From the bedside to the bench and back to the bedside."

Association of malnutrition-inflammation complex and responsiveness to erythropoiesis-stimulating agents in long-term hemodialysis patients

BACKGROUND

Protein-energy wasting, inflammation and refractory anemia are common in long-term hemodialysis patients. A decreased responsiveness to erythropoiesis-stimulating agents (ESA) is often the cause of the refractory anemia. We hypothesized that the malnutrition-inflammation complex is an independent predictor of decreased responsiveness to ESAs in hemodialysis patients.

METHODS

This cohort study of 754 hemodialysis patients was examined for an association between inflammatory and nutritional markers, including the malnutrition-inflammation score (MIS) and responsiveness to ESA. Cubic spline models were fitted to verify found associations.

RESULTS

The mean (±SD) age of patients was 54 ± 15 years, 53% were diabetic and 32% blacks. MIS was worse in the highest quartile of ESAs responsiveness index (ERI, ESA dose divided by hemoglobin) when compared with 1st quartile (6.5 ± 4.5 versus 4.4 ± 3.4; P < 0.001). Both C-reactive protein (log CRP) (β = 0.19) and interleukin-6 (log IL-6) (β = 0.32) were strong and independent predictors of ERI using multivariate linear regression. Serum albumin (β = -0.30) and prealbumin levels (β = -0.14) were inversely associated with ERI. Each 1 SD higher MIS, higher CRP and lower albumin were associated with 86, 44 and 97% higher likelihood of having highest versus three lowest ERI quartiles in fully adjusted models [odds ratio (and 95% confidence interval) of 1.86 (1.31-2.85), 1.44 (1.08-1.92) and 1.97 (1.41-2.78)], respectively. Cubic splines confirmed the continuous and incremental nature of these associations.

CONCLUSIONS

Malnutrition-inflammation complex is an incremental predictor of poor responsiveness to ESAs in hemodialysis patients. Further studies are needed to assess whether modulating inflammatory or nutritional processes can improve anemia management.

Exploring predisposition and treatment response--the promise of genomics

Spurred by large-scale public and private efforts as well as technological developments, the last few years have seen a major leap forward in our understanding of the genetic basis of cardiovascular disease. This revolution is in its infancy and will continue to alter the medical landscape for years to come. There is a need within the general cardiology community to develop a better understanding about how these developments may alter routine clinical care. In this review, we will provide an overview of the current state of genetics as pertains to rare cardiovascular diseases and then review advances in the discovery of the genetic basis of common disease with the potential for improved risk assessment and drug development. We will also outline a few recent examples of pharmacogenetic advances that are already starting to become a part of clinical management and finally discuss the promise as well as the challenges in using next-generation sequencing technologies to provide personalized cardiovascular care.

Gene-Diet Interactions in Complex Disease: Current Findings and Relevance for Public Health

Rates of obesity and related complex diseases such as type 2 diabetes and cardiovascular disease have climbed sharply over the past decades, in parallel with shift from principally more active lifestyle and nutritionally dense tradition diet to sedentary lifestyle and more energy-dense, Western-pattern diet. In the past few years, advances in genotyping technology and in particular a number of large-scale genome-wide association studies have made great strides in unraveling the genetic basis of complex diseases; and the growing inventory of genetic variation is facilitating efforts to investigate gene-diet interactions. Understanding gene-diet interaction has the potential to promote diet modifications on the basis of genetic makeup. Several recent large-scale studies found reproducible evidence showing consumption of sugar sweetened beverages or dietary patterns might modulate genetic predisposition to obesity or cardiovascular disease. Analyses in randomized trials also showed that genetic markers for obesity, diabetes, or cardiovascular disease might modify the metabolic response to weight-loss diets. However, little of the knowledge about gene-diet interaction has been applied in public health practice; and opinion on how genetic testing services are offered and interpreted is still divided. This review will summarize recent findings regarding obesogenic diet, genetic susceptibility, and gene-diet interactions for obesity and related complex disorders and will discuss the potential impact of these findings on public health practice.

Perspectives for metabolomics in testosterone replacement therapy

Testosterone is the major circulating androgen in men but exhibits an age-related decline in the ageing male. Late-onset hypogonadism or androgen deficiency syndrome (ADS) is a 'syndromic' disorder including both a persistent low testosterone serum concentration and major clinical symptoms, including erectile dysfunction, low libido, decreased muscle mass and strength, increased body fat, decreased vitality or depressed mood. Given its unspecific symptoms, treatment goals and monitoring parameters, this review will outline the various uncertainties concerning the diagnosis, therapy and monitoring of ADS to date. Literature was identified primarily through searches for specific investigators in the PubMed database. No date or language limits were applied in the literature search for the present review. The current state of research, showing that metabolomics is starting to have an impact not only on disease diagnosis and prognosis but also on drug treatment efficacy and safety monitoring, will be presented, and the application of metabolomics to improve the clinical management of ADS will be discussed. Finally, the scientific opportunities presented by metabolomics and other -omics as novel and promising tools for biomarker discovery and individualised testosterone replacement therapy in men will be explored.

Systematic testing of literature reported genetic variation associated with coronary restenosis: results of the GENDER Study

Background

Coronary restenosis after percutaneous coronary intervention still remains a significant problem, despite all medical advances. Unraveling the mechanisms leading to restenosis development remains challenging. Many studies have identified genetic markers associated with restenosis, but consistent replication of the reported markers is scarce. The aim of the current study was to analyze the joined effect of previously in literature reported candidate genes for restenosis in the GENetic DEterminants of Restenosis (GENDER) databank.

Methodology/Principal Findings

Candidate genes were selected using a MEDLINE search including the terms ‘genetic polymorphism’ and ‘coronary restenosis’. The final set included 36 genes. Subsequently, all single nucleotide polymorphisms (SNPs) in the genomic region of these genes were analyzed in GENDER using set-based analysis in PLINK. The GENDER databank contains genotypic data of 2,571,586 SNPs of 295 cases with restenosis and 571 matched controls. The set, including all 36 literature reported genes, was, indeed, significantly associated with restenosis, p = 0.024 in the GENDER study. Subsequent analyses of the individual genes demonstrated that the observed association of the complete set was determined by 6 of the 36 genes.

Conclusion

Despite overt inconsistencies in literature, with regard to individual candidate gene studies, this is the first study demonstrating that the joint effect of all these genes together, indeed, is associated with restenosis.

Gene regulatory networks in cardiac conduction system development

The cardiac conduction system is a specialized tract of myocardial cells responsible for maintaining normal cardiac rhythm. Given its critical role in coordinating cardiac performance, a detailed analysis of the molecular mechanisms underlying conduction system formation should inform our understanding of arrhythmia pathophysiology and affect the development of novel therapeutic strategies. Historically, the ability to distinguish cells of the conduction system from neighboring working myocytes presented a major technical challenge for performing comprehensive mechanistic studies. Early lineage tracing experiments suggested that conduction cells derive from cardiomyocyte precursors, and these claims have been substantiated by using more contemporary approaches. However, regional specialization of conduction cells adds an additional layer of complexity to this system, and it appears that different components of the conduction system utilize unique modes of developmental formation. The identification of numerous transcription factors and their downstream target genes involved in regional differentiation of the conduction system has provided insight into how lineage commitment is achieved. Furthermore, by adopting cutting-edge genetic techniques in combination with sophisticated phenotyping capabilities, investigators have made substantial progress in delineating the regulatory networks that orchestrate conduction system formation and their role in cardiac rhythm and physiology. This review describes the connectivity of these gene regulatory networks in cardiac conduction system development and discusses how they provide a foundation for understanding normal and pathological human cardiac rhythms.

Understanding cardiovascular disease: a journey through the genome (and what we found there)

Cardiovascular disease (CVD) is a major cause of mortality and hospitalization worldwide. Several risk factors have been identified that are strongly associated with the development of CVD. However, these explain only a fraction of cases, and the focus of research into the causes underlying the unexplained risk has shifted first to genetics and more recently to genomics. A genetic contribution to CVD has long been recognized; however, with the exception of certain conditions that show Mendelian inheritance, it has proved more challenging than anticipated to identify the precise genomic components responsible for the development of CVD. Genome-wide association studies (GWAS) have provided information about specific genetic variations associated with disease, but these are only now beginning to reveal the underlying molecular mechanisms. To fully understand the biological implications of these associations, we need to relate them to the exquisite, multilayered regulation of protein expression, which includes chromatin remodeling, regulatory elements, microRNAs and alternative splicing. Understanding how the information contained in the DNA relates to the operation of these regulatory layers will allow us not only to better predict the development of CVD but also to develop more effective therapies.

Impact of Next-Generation Sequencing (NGS) technology on cardiovascular disease research

In recent years, hundreds of gene loci associated with multiple cardiovascular pathologies and traits have been identified through high-throughput Next-Generation Sequencing (NGS) technology. Due to the increasing efficiency and decreasing cost of NGS, rapid progresses anticipated in the field of CVD research. This review summarizes the main strategies of CV research with NGS at the level of genomics, transcriptomics, epigenetics, and proteomics.

Genetics of human cardiovascular disease

Cardiovascular disease encompasses a range of conditions extending from myocardial infarction to congenital heart disease, most of which are heritable. Enormous effort has been invested in understanding the genes and specific DNA sequence variants that are responsible for this heritability. Here, we review the lessons learned for monogenic and common, complex forms of cardiovascular disease. We also discuss key challenges that remain for gene discovery and for moving from genomic localization to mechanistic insights, with an emphasis on the impact of next-generation sequencing and the use of pluripotent human cells to understand the mechanism by which genetic variation contributes to disease.

Darwinian natural selection: its enduring explanatory power

Evolutionary theory has never had a stronger scientific foundation than it does today. In a short review I hope to portray the deep commitment of today's biologists to Darwinian natural selection and to discoveries made since Darwin's time. In spite of the scientific advances in the century and a half since the publication of On the Origin of Species, Darwin still remains the principal author of modern evolutionary theory. He is one of the greatest contributors of all time to our understanding of nature.

Cell biology of ischemia/reperfusion injury

Disorders characterized by ischemia/reperfusion (I/R), such as myocardial infarction, stroke, and peripheral vascular disease, continue to be among the most frequent causes of debilitating disease and death. Tissue injury and/or death occur as a result of the initial ischemic insult, which is determined primarily by the magnitude and duration of the interruption in the blood supply, and then subsequent damage induced by reperfusion. During prolonged ischemia, ATP levels and intracellular pH decrease as a result of anaerobic metabolism and lactate accumulation. As a consequence, ATPase-dependent ion transport mechanisms become dysfunctional, contributing to increased intracellular and mitochondrial calcium levels (calcium overload), cell swelling and rupture, and cell death by necrotic, necroptotic, apoptotic, and autophagic mechanisms. Although oxygen levels are restored upon reperfusion, a surge in the generation of reactive oxygen species occurs and proinflammatory neutrophils infiltrate ischemic tissues to exacerbate ischemic injury. The pathologic events induced by I/R orchestrate the opening of the mitochondrial permeability transition pore, which appears to represent a common end-effector of the pathologic events initiated by I/R. The aim of this treatise is to provide a comprehensive review of the mechanisms underlying the development of I/R injury, from which it should be apparent that a combination of molecular and cellular approaches targeting multiple pathologic processes to limit the extent of I/R injury must be adopted to enhance resistance to cell death and increase regenerative capacity in order to effect long-lasting repair of ischemic tissues.

Calcineurin inhibitor nephrotoxicity

The use of the calcineurin inhibitors cyclosporine and tacrolimus led to major advances in the field of transplantation, with excellent short-term outcome. However, the chronic nephrotoxicity of these drugs is the Achilles' heel of current immunosuppressive regimens. In this review, the authors summarize the clinical features and histologic appearance of both acute and chronic calcineurin inhibitor nephrotoxicity in renal and nonrenal transplantation, together with the pitfalls in its diagnosis. The authors also review the available literature on the physiologic and molecular mechanisms underlying acute and chronic calcineurin inhibitor nephrotoxicity, and demonstrate that its development is related to both reversible alterations and irreversible damage to all compartments of the kidneys, including glomeruli, arterioles, and tubulo-interstitium. The main question--whether nephrotoxicity is secondary to the actions of cyclosporine and tacrolimus on the calcineurin-NFAT pathway--remains largely unanswered. The authors critically review the current evidence relating systemic blood levels of cyclosporine and tacrolimus to calcineurin inhibitor nephrotoxicity, and summarize the data suggesting that local exposure to cyclosporine or tacrolimus could be more important than systemic exposure. Finally, other local susceptibility factors for calcineurin inhibitor nephrotoxicity are reviewed, including variability in P-glycoprotein and CYP3A4/5 expression or activity, older kidney age, salt depletion, the use of nonsteroidal anti-inflammatory drugs, and genetic polymorphisms in genes like TGF-beta and ACE. Better insight into the mechanisms underlying calcineurin inhibitor nephrotoxicity might pave the way toward more targeted therapy or prevention of calcineurin inhibitor nephrotoxicity.