Lipoprotein(a) levels and risk of cardiovascular disease events in individuals with diabetes mellitus or prediabetes: The Atherosclerosis Risk in Communities study

BACKGROUND AND AIMS

Diabetes increases risk for atherosclerotic cardiovascular disease (ASCVD). Current guidelines do not recommend measuring lipoprotein(a), another ASCVD risk factor, in these individuals. We examined the association of lipoprotein(a) levels with incident ASCVD events in persons with and without diabetes or prediabetes.

METHODS

Lipoprotein(a) and other ASCVD risk factors were measured at baseline (1996-1998) in the biracial Atherosclerosis Risk in Communities study; participants without prevalent ASCVD (coronary heart disease or stroke) were monitored ∼15 years for incident ASCVD events.

RESULTS

Of 9871 eligible participants (mean age 63 years; 5816 women; 2155 African Americans), 1543 had diabetes and 3615 had prediabetes. Cumulative ASCVD incidence rates (event/1000-person years) were higher in participants with diabetes (26%) or prediabetes (13%) than in nondiabetic individuals (10%, p < 0.001). When comparing highest to lowest lipoprotein(a) categories (≥50 mg/dL vs. ≤10 mg/dL), increasing lipoprotein(a) levels were significantly associated with increasing incident ASCVD events in Caucasian participants with prediabetes (hazard ratio [HR] = 1.35; 95% confidence interval [CI] 1.07-1.69); p = 0.03) and diabetes (HR = 1.42; 95% CI 1.10-1.84; p < 0.01), but not those with normal fasting blood glucose. Adding lipoprotein(a) to Pooled Cohort Equation variables improved risk prediction in persons with diabetes (Δ in area under the receiver operating characteristic curve [AUC] 0.0087, net reclassification index [NRI] 0.1761) and prediabetes (ΔAUC 0.0025, NRI 0.0938).

CONCLUSIONS

In this biracial cohort, elevated lipoprotein(a) levels in Caucasian individuals with diabetes or prediabetes were associated with further increased ASCVD risk. Adding lipoprotein(a) to traditional risk factors improved ASCVD risk prediction.

Role of p90RSK in Kidney and Other Diseases

The 90 kDa ribosomal s6 kinases (RSKs) are a group of serine/threonine kinases consisting of 4 RSK isoforms (RSK1-4), of which RSK1 is also designated as p90RSK. p90RSK plays an important role in the Ras-mitogen-activated protein kinase (MAPK) signalling cascade and is the direct downstream effector of Ras-extracellular signal-regulated kinase (ERK1/2) signalling. ERK1/2 activation directly phosphorylates and activates p90RSK, which, in turn, activates various signalling events through selection of different phosphorylation substrates. Upregulation of p90RSK has been reported in numerous human diseases. p90RSK plays an important role in the regulation of diverse cellular processes. Thus, aberrant activation of p90RSK plays a critical role in the pathogenesis of organ dysfunction and damage. In this review, we focus on the current understanding of p90RSK functions and roles in the development and progression of kidney diseases. Roles of p90RSK, as well as other RSKs, in cardiovascular disorders and cancers are also discussed.

New Therapeutic Implications of Endothelial Nitric Oxide Synthase (eNOS) Function/Dysfunction in Cardiovascular Disease

The Global Burden of Disease Study identified cardiovascular risk factors as leading causes of global deaths and life years lost. Endothelial dysfunction represents a pathomechanism that is associated with most of these risk factors and stressors, and represents an early (subclinical) marker/predictor of atherosclerosis. Oxidative stress is a trigger of endothelial dysfunction and it is a hall-mark of cardiovascular diseases and of the risk factors/stressors that are responsible for their initiation. Endothelial function is largely based on endothelial nitric oxide synthase (eNOS) function and activity. Likewise, oxidative stress can lead to the loss of eNOS activity or even “uncoupling” of the enzyme by adverse regulation of well-defined “redox switches” in eNOS itself or up-/down-stream signaling molecules. Of note, not only eNOS function and activity in the endothelium are essential for vascular integrity and homeostasis, but also eNOS in perivascular adipose tissue plays an important role for these processes. Accordingly, eNOS protein represents an attractive therapeutic target that, so far, was not pharmacologically exploited. With our present work, we want to provide an overview on recent advances and future therapeutic strategies that could be used to target eNOS activity and function in cardiovascular (and other) diseases, including life style changes and epigenetic modulations. We highlight the redox-regulatory mechanisms in eNOS function and up- and down-stream signaling pathways (e.g., tetrahydrobiopterin metabolism and soluble guanylyl cyclase/cGMP pathway) and their potential pharmacological exploitation.

Prospective for cytochrome P450 epoxygenase cardiovascular and renal therapeutics

Therapeutics for arachidonic acid pathways began with the development of non-steroidal anti-inflammatory drugs that inhibit cyclooxygenase (COX). The enzymatic pathways and arachidonic acid metabolites and respective receptors have been successfully targeted and therapeutics developed for pain, inflammation, pulmonary and cardiovascular diseases. These drugs target the COX and lipoxygenase pathways but not the third branch for arachidonic acid metabolism, the cytochrome P450 (CYP) pathway. Small molecule compounds targeting enzymes and CYP epoxy-fatty acid metabolites have evolved rapidly over the last two decades. These therapeutics have primarily focused on inhibiting soluble epoxide hydrolase (sEH) or agonist mimetics for epoxyeicosatrienoic acids (EET). Based on preclinical animal model studies and human studies, major therapeutic indications for these sEH inhibitors and EET mimics/analogs are renal and cardiovascular diseases. Novel small molecules that inhibit sEH have advanced to human clinical trials and demonstrate promise for cardiovascular diseases. Challenges remain for sEH inhibitor and EET analog drug development; however, there is a high likelihood that a drug that acts on this third branch of arachidonic acid metabolism will be utilized to treat a cardiovascular or kidney disease in the next decade.

Chemical synthesis of 7-oxygenated 12α-hydroxy steroid derivatives to enable the biochemical characterization of cytochrome P450 8B1, the oxysterol 12α-hydroxylase enzyme implicated in cardiovascular health and obesity

Cholic acid is the endogenous 12α-hydroxylated bile acid, which possesses enhanced cholesterol absorption properties compared to its 12-desoxy counterpart, chenodeoxycholic acid. The oxysterol 12α-hydroxylase enzyme is cytochrome P450 8B1 (P450 8B1), which regioselectively and stereoselectively incorporates the 12α-hydroxy group in 7α-hydroxycholest-4-en-3-one, the biosynthetic precursor of cholic acid. Despite the vital role of P450 8B1 activity in cardiovascular health, research studies of other 12α-hydroxy steroid derivatives are rare. A synthetic route to incorporate a C12α-hydroxy group into the C12-methylene (-CH₂-) in dehydroepiandrosterone derivatives is disclosed. The incorporation of the C12-oxygen was accomplished through a copper mediated Schönecker oxidation of an imino-pyridine intermediate, introducing the 12β-hydroxy group. The resulting 12β-hydroxy steroid derivative was oxidized to the C12-ketone, which was stereoselectively reduced with lithium tri-sec-butylborohydride to afford the 12α-hydroxy stereochemistry. The C7-position was oxidized to yield the various 7-keto, 7β-hydroxy, and 7α-hydroxy derivatives. Furthermore, 7-ketodehydroepiandrosterone and 12 α-hydroxy-7-ketodehydroepiandrosterone both displayed NMDA receptor antagonistic activities at 10 μM concentrations. These C12α-hydroxy steroids will be used as tools to identify new biochemical properties of the enzymatic products of P450 8B1, the oxysterol 12α-hydroxylase.

Sialidase activity in human pathologies

Sialic acid residues are frequently located at the terminal positions of glycoconjugate chains of cellular glycocalyx. Sialidases, or neuraminidases, catalyse removal of these residues thereby modulating various normal and pathological cellular activities. Recent studies have revealed the involvement of sialidases in a wide range of human disorders, including neurodegenerative disorders, cancers, infectious diseases and cardiovascular diseases. The accumulating data make sialidases an interesting potential therapeutic target. Modulating the activity of these enzymes may have beneficial effects in several pathologies. Four types of mammalian sialidases have been described: NEU1, NEU2, NEU3 and NEU4. They are encoded by different genes and characterized by different subcellular localization. In this review, we will summarize the current knowledge on the roles of different sialidases in pathological conditions.

Impact of Cytochrome P450 2C19 Reduced-Function Polymorphism on Lesions and Clinical Outcome in Japanese Patients After Drug-eluting Stent Implantation

We previously reported that the cytochrome P450 (CYP) 2C19 reduced-function polymorphism was associated with decreased responsiveness to clopidogrel and intra-stent thrombus formation, as well as subsequent ischemic events after drug-eluting stent (DES) implantation. However, the relationship between the polymorphism and bleeding events remains unclear. Among 1427 consecutive patients who underwent DES implantation at Kobe University Hospital, 247 patients (341 lesions) were enrolled for this prospective observational study. All patients underwent follow-up optical coherence tomography (OCT) at 8 months and CYP2C19 genotyping. The patients were divided into three groups according to the phenotypic effect of the CYP2C19 polymorphism: extensive metabolizers (EM), intermediate metabolizers (IM), and poor metabolizers (PM). OCT findings, and ischemic and bleeding events were compared among the three groups. The frequency of intra-stent thrombi showed an increasing pattern among the patients with EM, IM, and PM (13.3%, 22.6%, and 33.3%, respectively; p = 0.04). The incidence of major adverse cardiovascular events (MACE) also showed an increase across the three groups from extensive to poor metabolizers (7.8%, 10.5%, and 33.3%, respectively; p < 0.01), whereas the frequency of bleeding showed no significant difference among the groups (15.6%, 19.4%, and 21.2%, respectively; p = 0.69). The CYP2C19 polymorphism is associated with the frequency of MACE, but is not related to the incidence of bleeding after percutaneous coronary intervention in Japanese patients receiving clopidogrel.

The Impact of Purinergic System Enzymes on Noncommunicable, Neurological, and Degenerative Diseases

Evidences show that purinergic signaling is involved in processes associated with health and disease, including noncommunicable, neurological, and degenerative diseases. These diseases strike from children to elderly and are generally characterized by progressive deterioration of cells, eventually leading to tissue or organ degeneration. These pathological conditions can be associated with disturbance in the signaling mediated by nucleotides and nucleosides of adenine, in expression or activity of extracellular ectonucleotidases and in activation of P2X and P2Y receptors. Among the best known of these diseases are atherosclerosis, hypertension, cancer, epilepsy, Alzheimer's disease (AD), Parkinson's disease (PD), and multiple sclerosis (MS). The currently available treatments present limited effectiveness and are mostly palliative. This review aims to present the role of purinergic signaling highlighting the ectonucleotidases E-NTPDase, E-NPP, E-5'-nucleotidase, and adenosine deaminase in noncommunicable, neurological, and degenerative diseases associated with the cardiovascular and central nervous systems and cancer. In conclusion, changes in the activity of ectonucleotidases were verified in all reviewed diseases. Although the role of ectonucleotidases still remains to be further investigated, evidences reviewed here can contribute to a better understanding of the molecular mechanisms of highly complex diseases, which majorly impact on patients' quality of life.

Paraoxonase (PON)-1: a brief overview on genetics, structure, polymorphisms and clinical relevance

Paraoxonase-1 (PON1) is a high-density lipoprotein-associated esterase and is speculated to play a role in several human diseases including diabetes mellitus and atherosclerosis. Low PON1 activity has been associated with increased risk of major cardiovascular events, therefore a variety of studies have been conducted to establish the cardioprotective properties and clinical relevance of PON1. The major aim of this review was to highlight the important studies and to subsequently assess if PON1 has clinical relevance. A review of the literature showed that there is currently insufficient data to suggest that PON1 has clinical relevance. It is our opinion that robust studies are required to clarify the clinical relevance of PON1.

PCSK9: From Basic Science Discoveries to Clinical Trials

Unknown 15 years ago, PCSK9 (proprotein convertase subtilisin/kexin type 9) is now common parlance among scientists and clinicians interested in prevention and treatment of atherosclerotic cardiovascular disease. What makes this story so special is not its recent discovery nor the fact that it uncovered previously unknown biology but rather that these important scientific insights have been translated into an effective medical therapy in record time. Indeed, the translation of this discovery to novel therapeutic serves as one of the best examples of how genetic insights can be leveraged into intelligent target drug discovery. The PCSK9 saga is unfolding quickly but is far from complete. Here, we review major scientific understandings as they relate to the role of PCSK9 in lipoprotein metabolism and atherosclerotic cardiovascular disease and the impact that therapies designed to inhibit its action are having in the clinical setting.

Association of endothelial dysfunction with cardiovascular risk factors and new-onset diabetes mellitus in patients with hypertension

Asymmetric dimethylarginine (ADMA), which is the main endogenous inhibitor of nitric oxide synthase, plays a critical role in the process of endothelial dysfunction. The authors evaluated the association between high plasma ADMA levels in patients with hypertension and the presence of cardiovascular risk factors and the development of type 2 diabetes mellitus (DM) and cardiovascular outcomes, including death. The authors evaluated 191 patients with hypertension who were stratified into two groups according to the median value of basal ADMA: those with high levels of plasma ADMA (>0.55 μmol/L) and low levels of plasma ADMA (≤0.55 μmol/L) who were prospectively evaluated over 5.8 years. High ADMA levels were seen in patients with higher weight, body mass index, waist circumference, triglycerides, uric acid, and high-sensitivity C-reactive protein, and lower levels of high-density lipoprotein cholesterol and in patients with type 2 DM. There was an association between high plasma ADMA levels and the occurrence of cardiovascular death. In a subgroup of patients with hypertension free from metabolic syndrome and DM at baseline, there was an association between high ADMA levels and the development of type 2 DM. This study confirms the association of high plasma ADMA levels and the presence of cardiovascular risk factors in patients with hypertension and suggests a positive predictive value of high plasma ADMA levels for cardiovascular death in patients with hypertension and also for the development of type 2 DM in a subgroup of patients with hypertension free from metabolic abnormalities.

Implication of liver enzymes on incident cardiovascular diseases and mortality: A nationwide population-based cohort study

Although liver enzymes, such as γ-glutamyltransferase (GGT), alanine aminotransferase (ALT), and aspartate aminotransferase (AST), have recently been suggested as risk factors for cardiovascular diseases (CVD), impact on mortality after myocardial infarction (MI) or ischemic stroke (IS) was not previously examined. Using a population-based, nationwide cohort database, we explored the implication of GGT and aminotransferases on the development of CVD and all-cause mortality during a median 9.1 years of follow-up. Among 16,624,006 Korean adults, both GGT and aminotransferases exhibited a positive relationship with MI, IS, and mortality in a multivariate adjusted model. ALT and AST showed U-shaped associations with mortality, whereas GGT showed a positive linear relationship with mortality. The risk of 1-year mortality after MI or IS was significantly higher in the highest quartile of GGT compared to the lowest quartile (HR, 1.46; 95% CI, 1.40-1.52). The implication of GGT on MI, IS, and mortality persisted regardless of traditional cardiovascular risk parameters. This study demonstrated the unique pattern of association of ALT, AST, and GGT with the development of CVD and all-cause mortality in the Korean population. In particular, GGT showed the most robust linear relationship with mortality before and after cardiovascular events independent of risk factors.

Role of Heme Oxygenases in Cardiovascular Syndromes and Co-morbidities

Cardiovascular Diseases (CVD), are the leading cause of human mortality worldwide and the focus of the intensive investigation is to characterize their pathogenesis. This review examines contribution to CVD of heme oxygenases (HOs), heat shock protein enzymes, comprising 3 isoforms: HO-1 (inducible), HO-2 (constitutively expressed) and HO-3 (function presently undefined), which constitute a primary endogenous countermeasure to oxidative tissue damage. Their role as CVD countermeasures is considered in the context of atherosclerosis, consequences of which are the leading cause of CVD deaths and from which 5 major syndromes may develop, namely: coronary artery disease and stroke, peripheral artery disease, kidney disease, cardiopulmonary disease and cerebrovascular disease. Over 75% of CVD deaths result from Coronary artery disease and stroke, with the severity of these conditions correlating with a systemic increase of the endogenous antioxidant bilirubin, produced by HO degradation of heme. Peripheral artery disease, (PAD) resulting from constricted arteries of the extremities is a painful and disabling condition, the severity of which correlates with elevated serum HO. Whether this represents an adaptive response or the enzyme is a contributor to PAD, remains to be determined. CVD symptoms, particularly hypertension, damage the vasculature and filtering structures of the kidneys and may be ameliorated by HO inducers. Interestingly, constitutive renal expression of HO-2 indicates that the enzyme is vital for healthy kidney function. Right ventricular hypertrophy and increased vascular resistance in blood vessels of the lungs exhibit mutually reinforcing positive feedback to result in cardiopulmonary heart disease, with morbidity and mortality resulting from associated inflammation and may be decreased with HO-1 inducers. Cerebrovascular disease, a major CVD complication affecting brain vasculature, with resulting susceptibility to stroke, maybe potently ameliorated by HO-1 inducers. Conclusion: Each of the six major categories of CVD exhibit features of pathogenesis that hold potential as future therapeutic targets, for modulated heme oxygenase activity.

[Epidemiology of hypercholesterolemia]

Hypercholesterolemia is one of the most important risk factors of cardiovascular (CV) disease. Epidemiology follows the prevalence, the incidence and the possibilities of risk factors or diseases intervention. A review of observation epidemiologic studies, pharmacotherapy and treatment perspectives is presented. The first epidemiologic studies, e.g. the Framingham Heart Study or MRFIT showed hyperlipidemia is associated with the incidence of CV disease. The North Karelia Project showed the intervention of CV risk factors is useful on population-based principles. Interventional studies with statins showed the usefulness of LDL cholesterol lowering to decrease CV morbidity and mortality and also total mortality. Anyway, the control of CV risk factors is unsatisfactory.Key words: epidemiology - hypercholesterolemia - intervention.

Pathological involvement of chymase-dependent angiotensin II formation in the development of cardiovascular disease

Chymase is a potent and specific angiotensin II (Ang II)-forming enzyme in vitro. There is also strong evidence to suggest its importance in vivo. Recent clinical studies have suggested that high serum cholesterol levels are associated with increased vascular chymase activity and this may assist in the development of atherosclerosis. This clinical finding has been reproduced in hamster models. Studies with transgenic mice overexpressing the human chymase gene suggest a direct association between vascular chymase upregulation and atherogenesis. There is also increased chymase activity following various cardiac diseases such as myocardial ischaemia, volume overload cardiac failure, cardiomyopathy and viral myocarditis, suggesting that increased cardiac chymase activity appears to be involved in cardiac remodelling.

Thymidine phosphorylase: A potential new target for treating cardiovascular disease

We recently found that thymidine phosphorylase (TYMP), also known as platelet-derived endothelial cell growth factor, plays an important role in platelet activation in vitro and thrombosis in vivo by participating in multiple signaling pathways. Platelets are a major source of TYMP. Since platelet-mediated clot formation is a key event in several fatal diseases, such as myocardial infarction, stroke and pulmonary embolism, understanding TYMP in depth may lead to uncovering novel mechanisms in the development of cardiovascular diseases. Targeting TYMP may become a novel therapeutic for cardiovascular disorders. In this review article, we summarize the discovery of TYMP and the potential molecular mechanisms of TYMP involved in the development of various diseases, especially cardiovascular diseases. We also offer insights regarding future studies exploring the role of TYMP in the development of cardiovascular disease as well as in therapy.

Chronicles of a reductase: Biochemistry, genetics and physio-pathological role of GSNOR

S-nitrosylation is a major redox posttranslational modification involved in cell signaling. The steady state concentration of S-nitrosylated proteins depends on the balance between the relative ability to generate nitric oxide (NO) via NO synthase and to reduce nitrosothiols by denitrosylases. Numerous works have been published in last decades regarding the role of NO and S-nitrosylation in the regulation of protein structure and function, and in driving cellular activities in vertebrates. Notwithstanding an increasing number of observations indicates that impairment of denitrosylation equally affects cellular homeostasis, there is still no report providing comprehensive knowledge on the impact that denitrosylation has on maintaining correct physiological processes and organ activities. Among denitrosylases, S-nitrosoglutathione reductase (GSNOR) represents the prototype enzyme to disclose how denitrosylation plays a crucial role in tuning NO-bioactivity and how much it deeply impacts on cell homeostasis and human patho-physiology. In this review we attempt to illustrate the history of GSNOR discovery and provide the evidence so far reported in support of GSNOR implications in development and human disease.

Alcohol Consumption, Aldehyde Dehydrogenase 2 Gene Polymorphisms, and Cardiovascular Health in Korea

Alcohol consumption is a serious health issue in Korea in terms of the amount consumed and the behavior related to its consumption. Aldehyde dehydrogenase 2 (ALDH2) is a key enzyme in alcohol metabolism that degrades acetaldehyde to nontoxic acetic acid. The enzyme is coded by the ALDH2 gene, which is commonly polymorphic in East Asian populations. A point mutation in the ALDH2 gene (the rs671 allele) yields an inactive form of ALDH2 that causes acetaldehyde accumulation in the body after alcohol consumption, thereby inhibiting normal alcohol metabolism. Individuals who are homozygous for polymorphism in ALDH2 tend to refrain from drinking alcohol, decreasing their chances of developing alcoholism and exposure to the associated risks. Mendelian randomization (MR) studies have demonstrated that alcohol consumption predicted by ALDH2 genotype is causally related to cardiovascular risks. Moreover, recent MR studies suggest that the ALDH2 variant has mechanistic effects on some disease outcomes or mortality through increased blood levels of acetaldehyde, showing differences therein between heterozygotes (ALDH2*2*2) and homozygotes (ALDH2*1*2) in those who consume alcohol. Accordingly, consideration of ALDH2 genotype in alcohol prevention programs is warranted. In conclusion, strategies that incorporate genetic information and provide an evidential basis from which to help people make informed decisions on alcohol consumption are urgently required.

AMP-Activated Protein Kinase: An Ubiquitous Signaling Pathway With Key Roles in the Cardiovascular System

The AMP-activated protein kinase (AMPK) is a key regulator of cellular and whole-body energy homeostasis, which acts to restore energy homoeostasis whenever cellular energy charge is depleted. Over the last 2 decades, it has become apparent that AMPK regulates several other cellular functions and has specific roles in cardiovascular tissues, acting to regulate cardiac metabolism and contractile function, as well as promoting anticontractile, anti-inflammatory, and antiatherogenic actions in blood vessels. In this review, we discuss the role of AMPK in the cardiovascular system, including the molecular basis of mutations in AMPK that alter cardiac physiology and the proposed mechanisms by which AMPK regulates vascular function under physiological and pathophysiological conditions.

Complexity of mechanisms among human proprotein convertase subtilisin-kexin type 9 variants

PURPOSE OF REVIEW

There are many reports of human variants in proprotein convertase subtilisin-kexin type 9 (PCSK9) that are either gain-of-function (GOF) or loss-of-function (LOF), with downstream effects on LDL cholesterol and cardiovascular disease (CVD) risk. However, data on particular mechanisms have only been minimally curated.

RECENT FINDINGS

GOF variants are individually ultrarare, affect all domains of the protein, act to reduce LDL receptor expression through several mechanisms, are a minor cause of familial hypercholesterolemia, have been reported mainly within families, have variable LDL cholesterol-raising effects, and are associated with increased CVD risk mainly through observational studies in families and small cohorts. In contrast, LOF variants can be either ultrarare mutations or relatively more common polymorphisms seen in populations, affect all domains of the protein, act to increase LDL receptor expression through several mechanisms, have variable LDL cholesterol-lowering effects, and have been associated with decreased CVD risk mainly through Mendelian randomization studies in epidemiologic populations.

SUMMARY

There is considerable complexity underlying the clinical concept of both LOF and GOF variants of PCSK9. But despite the underlying mechanistic heterogeneity, altered PCSK9 secretion or function is ultimately correlated with plasma LDL cholesterol level, which is also the driver of CVD outcomes.

[Klotho not only antiageing protein]

Klotho, the gene encoding the antiaging protein, was discovered in 1997 and named after a Greek Goddes who spun the thread of life. Numerous experiments on mice confirmed that destruction of the klotho gene or loss of klotho function leads to an accelerated aging and premature death. In addition to shortened life span, klotho-deficient mice demonstrated changes in functioning of multiple organs, ectopic calcification, enhanced development of arteriosclerosis, osteoporosis and atrophy of skin. In contrast, overexpression of a gene in mice inhibited aging and prolonged survival. The multisystemic phenotype induced by Klotho deficiency indicates that Klotho works on a variety of organs. Klotho is highly expressed in the kidney, brain, and to a lesser extent in other organs. Protein Klotho exists in two forms: membrane and secreted which play different functions. Membrane Klotho function as an obligate co-receptor required for signaling for the phosphaturic factor FGF23, regulates calcium-phosphate homeostasis through renal ion transport in addition to modulation of PTH and 1,25(OH)2D3. Soluble klotho functions as a humoral factor and regulates the activity of several ion channels and transporters. The secreted Klotho can also inhibit oxydative stres and the insulin and insulin-like growth factor 1 (IGF-1) pathways. The discovery of the protein klotho led to the identification of new axes connecting endocrine disturbances in the homeostasis of the calcium-phosphate to the aging of the organism. Klotho deficiency may not only be a trigger for accelerated aging but also in development of age- -associated diseases, including hypertension, osteoporosis, cardiovascular disease, and CKD. Conceivably, better understanding of Klotho protein might provide a novel treatment strategy for aging and age-associated diseases.

Identification and validation of seven new loci showing differential DNA methylation related to serum lipid profile: an epigenome-wide approach. The REGICOR study

Lipid traits (total, low-density and high-density lipoprotein cholesterol, and triglycerides) are risk factors for cardiovascular disease. DNA methylation is not only an inherited but also modifiable epigenetic mark that has been related to cardiovascular risk factors. Our aim was to identify loci showing differential DNA methylation related to serum lipid levels. Blood DNA methylation was assessed using the Illumina Human Methylation 450 BeadChip. A two-stage epigenome-wide association study was performed, with a discovery sample in the REGICOR study (n = 645) and validation in the Framingham Offspring Study (n = 2,542). Fourteen CpG sites located in nine genes (SREBF1, SREBF2, PHOSPHO1, SYNGAP1, ABCG1, CPT1A, MYLIP, TXNIP and SLC7A11) and 2 intergenic regions showed differential methylation in association with lipid traits. Six of these genes and 1 intergenic region were new discoveries showing differential methylation related to total cholesterol (SREBF2), HDL-cholesterol (PHOSPHO1, SYNGAP1 and an intergenic region in chromosome 2) and triglycerides (MYLIP, TXNIP and SLC7A11). These CpGs explained 0.7%, 9.5% and 18.9% of the variability of total cholesterol, HDL cholesterol and triglycerides in the Framingham Offspring Study, respectively. The expression of the genes SREBF2 and SREBF1 was inversely associated with methylation of their corresponding CpGs (P-value = 0.0042 and 0.0045, respectively) in participants of the GOLDN study (n = 98). In turn, SREBF1 expression was directly associated with HDL cholesterol (P-value = 0.0429). Genetic variants in SREBF1, PHOSPHO1, ABCG1 and CPT1A were also associated with lipid profile. Further research is warranted to functionally validate these new loci and assess the causality of new and established associations between these differentially methylated loci and lipid metabolism.

The aspartate aminotransferase-to-alanine aminotransferase ratio predicts all-cause and cardiovascular mortality in patients with type 2 diabetes

An increased aspartate aminotransferase-to-alanine aminotransferase ratio (AAR) has been widely used as a marker of advanced hepatic fibrosis. Increased AAR was also shown to be significantly associated with the risk of developing cardiovascular (CV) disease. The aim of this study was to assess the relationship between the AAR and mortality risk in a well-characterized cohort of patients with type 2 diabetes.A cohort of 2529 type 2 diabetic outpatients was followed-up for 6 years to collect cause-specific mortality. Cox regression analyses were modeled to estimate the independent association between AAR and the risk of all-cause and CV mortality.Over the 6-year follow-up period, 12.1% of patients died, 47.5% of whom from CV causes. An increased AAR, but not its individual components, was significantly associated with an increased risk of all-cause (adjusted-hazard risk 1.83, confidence interval [CI] 95% 1.14-2.93, P = 0.012) and CV (adjusted-hazard risk 2.60, CI 95% 1.38-4.90, P < 0.003) mortality after adjustment for multiple clinical risk factors and potential confounding variables.The AAR was independently associated with an increased risk of both all-cause and CV mortality in patients with type 2 diabetes. These findings suggest that an increased AAR may reflect more systemic derangements that are not simply limited to liver damage. Further studies are needed to elucidate the pathophysiological implications of an increased AAR.

Cardiovascular effects of cyclooxygenase-2 inhibitors: a mechanistic and clinical perspective

LINKED ARTICLES

This article is part of a joint Themed section with the British Journal of Pharmacology on Targeting Inflammation to Reduce Cardiovascular Disease Risk: a Realistic Clinical Prospect? The rest of the Themed section will appear in a future issue of BJP and will be available at http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1476-5381 Prostaglandin (PG) H synthase 2 [also referred to colloquially as cyclooxygenase (COX) 2] represents a key enzyme in arachidonic acid metabolism in health and disease. It is both constitutively expressed in several human tissues (e.g. kidney and brain) and induced in various cell types (including monocytes/macrophages, vascular endothelial cells and colorectal cancer cells) in response to inflammatory cytokines, laminar shear stress and growth factors. Products of COX-2 activity (e.g. PGE2 and prostacyclin) are involved in diverse physiological and pathophysiological processes, including renal haemodynamics and the control of blood pressure, endothelial thromboresistance, pain and inflammation, and colorectal tumorigenesis. Therefore, it is not surprising that COX-2 inhibitors display multifaceted clinical effects, ranging from reduced pain and inflammation to increased blood pressure, an increased risk of atherothrombotic events and a decreased risk of colorectal cancer. The aim of the present article was to review the cardiovascular effects of COX-2 inhibitors [traditional nonsteroidal anti-inflammatory drugs (tNSAIDs) and coxibs alike], with a focus on the mechanisms contributing to the clinical readouts of COX-2 inhibition.