A common promoter polymorphism in the hepatic lipase gene (LIPC-480C>T) is associated with an increase in coronary calcification in type 1 diabetes

The Association of Coronary Artery Calcification With Subsequent Incidence of Cardiovascular Disease in Type 1 Diabetes: The DCCT/EDIC Trials

OBJECTIVES

This study sought to determine the relationship between coronary artery calcium (CAC) scores and subsequent cardiovascular disease (CVD) events in DCCT (Diabetes Control and Complications Trial)/EDIC (Epidemiology of Diabetes Interventions and Complications) participants.

BACKGROUND

The CAC score has been validated for improved risk stratification in general populations; however, this association has not been well studied in type 1 diabetes (T1DM).

METHODS

Computed tomography (CT) to measure CAC was performed in 1,205 DCCT/EDIC participants at a mean of 42.8 years of age during EDIC years 7 to 9, after the end of DCCT. This study analyzed the association between CAC and time to the first subsequent CVD event or to the first major adverse cardiac event (MACE), a follow-up of 10 to 13 years. CAC was categorized as: 0, >0 to 100, >100 to 300, or >300 Agatston units.

RESULTS

Of 1,156 participants at risk for subsequent CVD, 105 had an initial CVD event (8.5 per 1,000 patient-years); and of 1,187 participants at risk for MACE, 51 had an initial MACE event (3.9 per 1,000 patient-years). Event rates among those with scores of zero (n = 817 [70.7%]) were very low for CVD (5.6 per 1,000 patient years). CAC scores >100 to 300 (hazard ratio [HR]: 4.17, 5.40) and >300 (HR: 6.06, 6.91) were associated with higher risks of CVD and MACE, respectively, compared to CAC of 0 (p < 0.0001). CAC scores >0 to 100 were nominally associated with CVD (HR: 1.71; p = 0.0415) but not with MACE (HR: 1.11; p = 0.8134). Similar results were observed when also adjusted for mean HbA1c and conventional CVD risk factors. The increment in the AUC due to CAC was modest.

CONCLUSIONS

CAC scores >100 Agatston units were significantly associated with an increased risk of the subsequent occurrence of CVD and MACE in DCCT/EDIC cohort. (Diabetes Control and Complications Trial [DCCT]; NCT00360815; Epidemiology of Diabetes Interventions and Complications [EDIC]; NCT00360893).

Novel risk genes identified in a genome-wide association study for coronary artery disease in patients with type 1 diabetes

Background

Patients with type 1 diabetes are more at risk of coronary artery disease than the general population. Although evidence points to a genetic risk there have been no study investigating genetic risk factors of coronary artery disease specific to individuals with type 1 diabetes. To identify low frequency and common genetic variations associated with coronary artery disease in populations of individuals with type 1 diabetes.

Methods

A two-stage genome wide association study was conducted. The discovery phase involved the meta-analysis of three genome-wide association cohorts totaling 434 patients with type 1 diabetes and coronary artery disease (cases) and 3123 T1D individuals with no evidence of coronary artery disease (controls). Replication of the top association signals (p < 10⁻⁵) was performed in five additional independent cohorts totaling 585 cases and 2612 controls.

Results

One locus (rs115829748, located upstream of the MAP1B gene) reached the statistical threshold of 5 × 10⁻⁸ for genome-wide significance but did not replicate. Nevertheless, three single nucleotide polymorphisms provided suggestive evidence for association with coronary artery disease in the combined studies: CDK18 rs138760780 (OR = 2.60 95% confidence interval [1.75–3.85], p = 2.02 × 10⁻⁶), FAM189A2 rs12344245 (OR = 1.85 [1.41–2.43], p = 8.52 × 10⁻⁶) and PKD1 rs116092985 (OR = 1.53 [1.27–1.85], p = 1.01 × 10⁻⁵). In addition, our analyses suggested that genetic variations at the ANKS1A, COL4A2 and APOE loci previously found associated with coronary artery disease in the general population could have stronger effects in patients with type 1 diabetes.

Conclusions

This study suggests three novel candidate genes for coronary artery disease in the subgroup of patients affected with type 1 diabetes. The detected associations deserve to be definitively validated in additional epidemiological studies.

Electronic supplementary material

The online version of this article (10.1186/s12933-018-0705-0) contains supplementary material, which is available to authorized users.

Noninvasive Cardiovascular Risk Assessment of the Asymptomatic Diabetic Patient: The Imaging Council of the American College of Cardiology

Increased cardiovascular morbidity and mortality in patients with type 2 diabetes is well established; diabetes is associated with at least a 2-fold increased risk of coronary heart disease. Approximately two-thirds of deaths among persons with diabetes are related to cardiovascular disease. Previously, diabetes was regarded as a "coronary risk equivalent," implying a high 10-year cardiovascular risk for every diabetes patient. Following the original study by Haffner et al., multiple studies from different cohorts provided varying conclusions on the validity of the concept of coronary risk equivalency in patients with diabetes. New guidelines have started to acknowledge the heterogeneity in risk and include different treatment recommendations for diabetic patients without other risk factors who are considered to be at lower risk. Furthermore, guidelines have suggested that further risk stratification in patients with diabetes is warranted before universal treatment. The Imaging Council of the American College of Cardiology systematically reviewed all modalities commonly used for risk stratification in persons with diabetes mellitus and summarized the data and recommendations. This document reviews the evidence regarding the use of noninvasive testing to stratify asymptomatic patients with diabetes with regard to coronary heart disease risk and develops an algorithm for screening based on available data.

Lipoprotein composition in patients with type 1 diabetes mellitus: Impact of lipases and adipokines

OBJECTIVE

High cardiovascular mortality in patients with type 1 diabetes (T1DM) is widely recognized. Paradoxically, these patients have been shown to have elevated HDL-C and reduced apoB-containing lipoproteins. The purpose of this investigation was to further characterize the lipoprotein composition in T1DM and to assess the role that lipases and adipokines may play in these differences.

METHODS

T1DM patients (89) attending the Diabetes Clinic at the University of Miami and 42 healthy controls were recruited. Clinical characteristics, lipoprotein composition (by ultracentrifugation and HPLC), leptin, and adiponectin were measured in the full cohort, while a subgroup had LPL and hepatic lipase measured.

RESULTS

Subjects were predominately Caucasian and Hispanic. HgbA1c's were above goal while their mean duration of diabetes was >20 years. LPL was 2-fold elevated in diabetic women versus controls (+107%{p=0.001}) with no difference in men. Hepatic lipase was reduced 50% {p<0.001} in women but increased 50% {p=0.079} in men. Leptin was similar to controls in women but reduced in men (-60%{p<0.001}). Adiponectin was elevated in both genders (men: +55%{p=0.018}; women: +46%{p=0.007}). LDL-C was reduced in both diabetic men (-33%{p<0.001}) and women (-24%{p<0.001}) while HDL-C trended higher only in men (+13%{p=0.064}). Both total apoB (men: -31%{p<0.001}; women: -17%{p=0.016}) and triglycerides (men: -49%{p<0.001}; women: -31%{p=0.011}) were reduced in both genders while total apoA-I was increased in both (men: +31%{p<0.001}; women: +19%{p=0.008}). Both men and women had increases in LpA-I (+66%{p<0.001}; +40%{p=0.001}) which accounted for essentially the entire increase in HDL mass. VLDL lipids (men: -53→70%; women: -31→57%) were lower as was apoB (particle number) in men (-51{p<0.001}) with a similar trend in women (-35%{p=0.066}). Cholesterol esters in the particle core were depleted in both genders relative to both apoB (men: -41%; women: -37%) and triglycerides (men: -38%; women: -34%) (all{p<0.009}). There were similar differences in IDL. HDL-L lipids (except triglycerides) (men: +45→74%; women: +49→77%{p<0.006}), apoA-1 (men: +162%; women: +117%{p<0.001}), and apoA-II (men: +64%{p=0.008}; women: +55%{p=0.014}) were higher in T1DM patients. These differences produced dramatic increases in LpA-I (men: +221%; women +139%{p<0.001}) and total HDL-L mass (men: +85%; women: +78%{p<0.001}). ApoM (men: +190%; women: +149%{p<0.001}) was also dramatically increased. Conversely, HDL-D lipids were lower in both genders (-20%→50%) while apoA-I was not different in either. ApoA-II was lower only in the diabetic women (-25%{p=0.015}). LPL activity correlated primarily with IDL(-), LDL(-), HDL-L(+), and HDL-D(-) only in the women. HL correlated weakly with VLDL(+), LDL(+), HDL-L(-), and HDL-D(+) in women but had much stronger correlations with VLDL(-), IDL(-), and HDL-L(+). Adiponectin correlated with VLDL(-), IDL(-), LDL(-), HDL-L(+), and HDL-D(-) in women but only HDL-L(+) and HDL-D(-) in men. Leptin correlated with very few parameters in women but did correlate weakly with several HDL-L(-) and HDL-M(-) parameters.

CONCLUSION

Lipoprotein composition and adipokine concentrations in both genders as well as lipase activities in the women would be expected to reduce the atherosclerotic risk in these patients with T1DM. These data suggest that there are functional lipoprotein abnormalities responsible for their CV risk that are not reflected in their plasma concentrations.

LCAT, HDL cholesterol and ischemic cardiovascular disease: a Mendelian randomization study of HDL cholesterol in 54,500 individuals

BACKGROUND

Epidemiologically, high-density lipoprotein (HDL) cholesterol levels associate inversely with risk of ischemic cardiovascular disease. Whether this is a causal relation is unclear.

METHODS

We studied 10,281 participants in the Copenhagen City Heart Study (CCHS) and 50,523 participants in the Copenhagen General Population Study (CGPS), of which 991 and 1,693 participants, respectively, had developed myocardial infarction (MI) by August 2010. Participants in the CCHS were genotyped for all six variants identified by resequencing lecithin-cholesterol acyltransferase in 380 individuals. One variant, S208T (rs4986970, allele frequency 4%), associated with HDL cholesterol levels in both the CCHS and the CGPS was used to study causality of HDL cholesterol using instrumental variable analysis.

RESULTS

Epidemiologically, in the CCHS, a 13% (0.21 mmol/liter) decrease in plasma HDL cholesterol levels was associated with an 18% increase in risk of MI. S208T associated with a 13% (0.21 mmol/liter) decrease in HDL cholesterol levels but not with increased risk of MI or other ischemic end points. The causal odds ratio for MI for a 50% reduction in plasma HDL cholesterol due to S208T genotype in both studies combined was 0.49 (0.11-2.16), whereas the hazard ratio for MI for a 50% reduction in plasma HDL cholesterol in the CCHS was 2.11 (1.70-2.62) (P(comparison) = 0.03).

CONCLUSION

Low plasma HDL cholesterol levels robustly associated with increased risk of MI but genetically decreased HDL cholesterol did not. This may suggest that low HDL cholesterol levels per se do not cause MI.

Hepatic lipase, genetically elevated high-density lipoprotein, and risk of ischemic cardiovascular disease

CONTEXT

Hepatic lipase influences metabolism of high-density lipoprotein (HDL), a risk factor for ischemic cardiovascular disease (ICD: ischemic heart disease and ischemic cerebrovascular disease).

OBJECTIVE

We tested the hypothesis that genetic variation in the hepatic lipase genetic variants V73M, N193S, S267F, L334F, T383M, and -480c>t influence levels of lipids, lipoproteins, and apolipoproteins and risk of ICD.

DESIGN

For the cross-sectional study, we genotyped 9003 individuals from the Copenhagen City Heart Study; hereof were 8971 individuals included in the prospective study, 1747 of whom had incident ICD during 28 yr of follow-up. For the case-control studies, 2110 ischemic heart disease patients vs. 4899 controls and 769 ischemic cerebrovascular disease patients vs. 2836 controls, respectively, were genotyped. Follow-up was 100% complete.

RESULTS

HDL cholesterol was higher by 0.21 mmol/liter in S267F heterozygotes, by 0.06 mmol/liter in -480c>t heterozygotes, and by 0.13 mmol/liter in -480c>t homozygotes, as compared with noncarriers. These HDL increases theoretically predicted hazard ratios for ICD of 0.87 [95% confidence interval (CI) 0.84-0.90], 0.96 (95% CI 0.95-0.97), and 0.91 (95% CI 0.89-0.94), respectively; this calculation assumes that genetically elevated HDL levels confer decreased risk similar to common HDL elevations. In contrast, when all cases and controls were combined, the observed odds ratios for ICD for these three genetic variants vs. noncarriers were 1.19 (0.76-1.88), 1.04 (0.96-1.13), and 1.08 (0.89-1.30), respectively. Hazard/odds ratios for ICD in carriers vs. noncarriers of the four remaining hepatic lipase genetic variants did not differ consistently from 1.0.

CONCLUSION

Hepatic lipase genetic variants with elevated levels of HDL cholesterol did not associate with risk of ICD.

Type 1 diabetes, hyperglycaemia, and the heart

Type 1 diabetes is associated with a substantially increased risk of cardiovascular disease that might not always be appreciated in view of the fairly young age of patients with this condition. In fact, in type 1 diabetes, the heart is subject to a variety of pathological insults, including accelerated atherosclerosis, cardiac autonomic neuropathy, and possibly intrinsic cardiomyopathy. Although the relation between hyperglycaemia and microvascular complications has been well established, a direct effect of hyperglycaemia on cardiovascular disease in type 1 diabetes has long been debated. More recently, several studies, most notably the Diabetes Control and Complications Trial/Epidemiology of Diabetes Interventions and Complications, have clarified this issue and provided conclusive evidence that hyperglycaemia is indeed a mediator of cardiovascular risk in type 1 diabetes and that intensive diabetes therapy can reduce cardiovascular disease outcomes. We review current concepts in type 1 diabetes and the heart, focusing on recent insights into the central role of hyperglycaemia.

Genetic Variation in ABCA1 Predicts Ischemic Heart Disease in the General Population

Objective— We tested the hypothesis that 6 nonsynonymous single nucleotide polymorphisms (SNPs) in ATP-Binding-Cassette transporter A1 (ABCA1 ) affect risk of ischemic heart disease (IHD) in the general population.

Methods and Results— We genotyped 9259 individuals from the Danish general population followed for 25 years. Two SNPs (V771M and V825I) were previously associated with increases in HDL-C, 1 (R1587K) with decreased HDL-C, whereas 3 (R219K, I883M and E1172D) did not affect HDL-C levels. Despite this, 5 out of 6 SNPs (V771M, V825I, I883M, E1172D, R1587K) predicted increased risk of IHD. Similar results were obtained in a verification sample with 932 IHD cases versus 7999 controls. A stepwise regression approach identified V771M, I883M, and E1172D as the most important predictors of IHD and additive effects on IHD risk were present for V771M/I883M and I883M/E1172D pairs.

Conclusions— We show that 3 of 6 nonsynonymous SNPs in ABCA1 predict risk of IHD in the general population.

Lower-extremity arterial calcification as a correlate of coronary artery calcification

Coronary artery calcification (CAC) has been used as a testing modality for coronary atherosclerosis burden. In diabetes, arterial calcification in the tunica media is common and predicts renal and cardiovascular mortality. It is unknown whether the 2 calcification processes are related. We identified risk factors associated with lower-extremity arterial calcification (LEAC) and determined its relationship to the presence of CAC 6 years later and the incidence of complications in type 1 diabetes mellitus. A random sample of 190 participants from the Pittsburgh Epidemiology of Diabetes Complications Study, a prospective cohort of childhood-onset type 1 diabetes mellitus, received radiographs of their ankles and feet at the 4-year follow-up examination (1990-1992) and was followed up for approximately 6 years. At the 10-year examination, 121 of these individuals received an electron beam tomography scan. Male sex (odds ratio [OR] = 12.72, P < .0001), diabetes duration (OR = 4.53, P < .0001), and autonomic neuropathy (AN; OR = 5.92, P = .007) independently increased the odds of LEAC. Controlling for other known risk factors (duration and high-density lipoprotein cholesterol), we found that LEAC correlated with the presence of CAC 6 years later (OR = 1.12, P = .03), although adjusting for neuropathy attenuated this relationship (P = .08). LEAC also independently predicted AN but not the onset of other diabetes complications. Although arterial calcification in the lower extremities and the heart share many of the same risk factors, LEAC is an independent correlate of the later presence of CAC and AN. Thus, factors related to the calcification process in addition to vascular risk factors may play a role in determining the extent of CAC.

Identifying genetic susceptibilities to diabetes-related complications among individuals at low risk of complications: An application of tree-structured survival analysis

The authors hypothesized that genetic predisposition to diabetes complications would be more evident among low-risk individuals and aimed to identify genes related to developing complications (confirmed distal symmetric polyneuropathy, overt nephropathy, or coronary artery disease) in low-risk groups. Participants in the Pittsburgh, Pennsylvania, Epidemiology of Diabetes Complications Study of childhood-onset type 1 diabetes, first seen in 1986-1988 (mean age, 28 years; diabetes duration, 19 years), were reexamined biennially for 10 years. For each complication, subgroups with the lowest disease risk were identified by using tree-structured survival analysis, and 15 candidate genes were compared between subjects with and without complications. In the group with the lowest incidence of confirmed distal symmetric polyneuropathy (n = 123), confirmed distal symmetric polyneuropathy risk increased fivefold for those with the eNOS GG genotype (p < 0.05). In the group with the lowest risk of overt nephropathy (n = 340), the ACE D polymorphism increased overt nephropathy risk twofold (p = 0.05), whereas a protective effect was observed for the LIPC CC genotype (p < 0.05). In the group with the lowest incidence of coronary artery disease (n = 331), the MTHFR CC genotype increased coronary artery disease risk threefold (p < 0.05). Tree-structured survival analysis may help identify genetic predispositions among individuals who, despite low risk, develop diabetes-related complications.

The influence of hepatic lipase C-480T polymorphism on coronary flow reserve in young men is independent of the plasma cholesterol level

BACKGROUND

The hepatic lipase (HL) gene C-480T promoter polymorphism affects gene transcription and enzyme activity and leads to CC, CT, and TT genotypes. Recently, HL expression was detected in macrophages. It has been postulated that HL might have a direct role in the pathogenesis of atherosclerosis without changes in the plasma profile. We hypothesized that the difference of plasma cholesterol level may not influence the effect of HL genotype on coronary reactivity.

METHODS

A total of 108 young men (aged 34+/-5 years) were genotyped and divided into three groups. These groups contained 45, 49 and 14 men having either normal (4.9+/-1.2 mmol/L), mildly (5.5+/-0.8 mmol/L) or severely (7.8+/-1.9 mmol/L, subjects with familial hypercholesterolemia) elevated mean plasma cholesterol level, respectively. Myocardial blood flow (MBF) was measured at rest and during adenosine or dipyridamole-induced hyperemia with positron emission tomography using [(15)O] H(2)O.

RESULTS

The effect of HL genotype on the indices of MBF was parallel within all cholesterol groups and therefore they were combined. In all subjects, basal flow did not differ between the genotypes. However, men with CC genotype had a significantly higher hyperemic blood flow (3.86+/-1.26 mLg(-1)min(-1) versus 3.20+/-1.38 mLg(-1)min(-1), p=0.007), higher coronary flow reserve (CFR, 4.80+/-1.77 versus 3.77+/-1.43, p=0.001) and lower coronary resistance during hyperemia (25.63+/-9.98 mmHg min g mL(-1) versus 35.00+/-23.95 mmHg min g mL(-1), p=0.003) than T allele carriers. In multivariate regression analysis, after adjustment for age, body mass index, serum lipids, blood pressure, adenosine or dipyridamole administration, and study group, HL polymorphism was an independent predictor of blood flow during hyperemia (p=0.016), coronary resistance (p=0.014), and CFR (p=0.005), respectively.

CONCLUSIONS

The HL C-480 T polymorphism is associated with CFR, which is an early indicator of atherosclerosis, independently of the level of plasma cholesterol in young men.

Thematic review series: Patient-Oriented Research. Imaging atherosclerosis: state of the art

The ability to image obstructive arterial disease brought about a revolution in clinical cardiovascular care; the development of newer technologies that image arterial wall thicknesses, areas, volumes, and composition allows valid imaging of atherosclerosis for the first time. Development of noninvasive imaging of atherosclerosis has further led to a quantum shift in research in the field by enabling the study of asymptomatic populations and thus allowing investigators to focus on preclinical disease without the many biases associated with the study of symptomatic patients. These noninvasive investigations have broad implications for clinical care as well. Coronary angiography, computed tomographic (CT) imaging of coronary calcium, intravascular ultrasound, multidetector CT angiography, B mode ultrasound of the carotid arteries, and MRI of the carotid arteries all have unique strengths and weaknesses for imaging atherosclerosis. Certain of these techniques are extremely useful as outcome variables for clinical trials, and others are uniquely useful as predictors of the risk of cardiovascular disease. All are informative in one way or another with regard to the role of plaque remodeling and composition in disease causation. CT and MRI technology are advancing very rapidly, and research and clinical uses of these imaging modalities promise to further advance our understanding of atherosclerosis and its prevention.

The apolipoprotein A-IV Gln360His polymorphism predicts progression of coronary artery calcification in patients with type 1 diabetes

AIMS/HYPOTHESIS

Individuals with type 1 diabetes have an increased incidence of coronary artery disease (CAD) and a higher risk of cardiovascular death compared with individuals of the same age in the general population. While chronic hyperglycaemia and insulin resistance partially explain excess CAD, little is known about the potential genetic determinants of accelerated coronary atherosclerosis in type 1 diabetes. The aim of the present study was to evaluate the association of apolipoprotein A-IV (APOA4) polymorphisms with coronary artery calcification (CAC) progression, a marker of subclinical atherosclerosis.

SUBJECTS AND METHODS

Two previously well-studied functional APOA4 polymorphisms resulting in the substitution of the amino acid Thr for Ser at codon 347 and Gln for His at codon 360 were genotyped in 634 subjects with type 1 diabetes and 739 non-diabetic control subjects, the participants of the prospective Coronary Artery Calcification in Type 1 Diabetes (CACTI) study.

RESULTS

The His360 allele was associated with a significantly higher risk of CAC progression among patients with type 1 diabetes (33.7 vs 21.2%, p=0.014), but not in the control subjects (14.1 vs 11.1%, p=0.42). Logistic regression analysis confirmed that the presence of the APOA4 His360 allele predicts an increased risk of progression of coronary atherosclerosis in adults with type 1 diabetes of long duration (odds ratio = 3.3, p=0.003 after adjustment for covariates associated with CAD risk). CONCLUSIONS /INTERPRETATION: This is the first report suggesting an association between the APOA4 Gln360His polymorphism and risk of CAC progression in subjects with type 1 diabetes. Additional studies are needed to explore potential interactions between APOA4 genotypes and metabolic/oxidative stress components of the diabetic milieu leading to rapid progression of atherosclerosis.

Genetic variation in the hepatic lipase gene and the risk of coronary heart disease among US diabetic men: potential interaction with obesity

AIMS/HYPOTHESIS

The -514 C to T polymorphism of the hepatic lipase gene (LIPC) has been associated with lowered LIPC activity and elevated HDL-cholesterol concentrations. Previous findings on the association of this polymorphism with the risk of CHD are inconsistent. Moreover, data on this association among diabetic patients are limited. We investigated the association of the LIPC polymorphism with CHD risk among US diabetic men and evaluated whether this association was modified by adiposity status.

SUBJECTS AND METHODS

The case group consisted of 220 diabetic men who were recruited from the Health Professionals Follow-up Study (years 1986-2000) and were free of cardiovascular disease at baseline, but subsequently developed CHD. A total of 641 diabetic men from the same study but without cardiovascular disease constituted the control group.

RESULTS

No overall association between the LIPC polymorphism and CHD risk was observed. However, we did observe a significant interaction between this polymorphism and BMI in association with CHD risk. Among obese men, after adjustment for age, duration of diabetes and major lifestyle factors, the CT or TT genotype was associated with an increased CHD risk compared with the CC genotype (odds ratio [OR] 2.52, 95% CI 1.08-5.90); the corresponding ORs (95% CI) were 0.99 (0.58, 1.69) for overweight men (25< or =BMI <30 kg/m(2)) and 0.37 (0.17, 0.79) for lean men (BMI <25 kg/m(2)) (p for interaction 0.001). Stratified analyses by waist circumference (tertiles) showed a similar pattern of interaction (adjusted p for interaction 0.023).

CONCLUSION/INTERPRETATION

These data suggest that obesity may modify the association between the LIPC C(-514)T polymorphism and CHD risk among diabetic men.

Age-dependent association between hepatic lipase gene C-480T polymorphism and the risk of pre-hospital sudden cardiac death: the Helsinki Sudden Death Study

OBJECTIVE

We investigated the association between hepatic lipase (HL) C-480T polymorphism and the risk of acute myocardial infarction (AMI) as well as pre-hospital sudden cardiac death (SCD).

METHODS

Seven hundred sudden or unnatural pre-hospital deaths of middle-aged (33-70 years, mean 53 years) Caucasian Finnish men were subjected to detailed autopsy (Helsinki Sudden Death Study). Genotype data were obtained for 682 men.

RESULTS

In logistic regression analysis with age, body mass index, hypertension, diabetes, smoking and alcohol consumption as covariates, men with the TT genotype had an increased risk for SCD and AMI compared to CC carriers (OR=3.0, P=0.011; and OR=3.7, P=0.003). There was a significant age-by-genotype interaction (P<0.05) on the risk of SCD. Compared to CC genotype carriers, the association between the TT genotype and SCD was particularly strong (P=0.001) among men <53 years of age, but this association was non-significant among older men. This was mainly due to a strong association between the TT genotype and AMI due to severe coronary disease in the absence of thrombosis. Carriers of the TT genotype were more likely to have severe coronary stenoses (> or =50%) than men with the CT or CC genotype (P=0.019).

CONCLUSIONS

The results suggest that HL C-480T polymorphism is a strong age-dependent risk factor of SCD in early middle-aged men.

Ischemia imaging and plaque imaging in diabetes: complementary tools to improve cardiovascular risk management

Cardiovascular disease is the most frequent cause of death and disability in diabetes, and the morbidity and mortality for coronary artery disease (CAD) in this population is two to four times higher than in nondiabetic subjects. Traditional risk factors do not fully explain the level of cardiovascular risk, and coronary disease events are often silent in diabetic patients. Thus, research has recently focused on improving the risk assessment of an individual patient with new tools in an effort to better identify subjects at highest risk and in need of aggressive management. Cardiovascular imaging has proven very helpful in this regard. Traditional methods to assess CAD are based on detection of obstructive luminal disease responsible for myocardial ischemia. However, acute coronary syndromes often occur in the absence of luminal stenoses. Hence, the utilization of imaging methodologies to visualize atherosclerosis in its presymptomatic stages has received mounting attention in recent years. In this article, we review the current literature on the utility of traditional imaging modalities for obstructive CAD (nuclear and echocardiographic stress testing) as well as atherosclerosis plaque imaging with carotid intima-media thickness and coronary artery calcium for risk stratification of diabetic patients.

Hepatic lipase polymorphism and increased risk of peripheral arterial disease

BACKGROUND

Hepatic lipase plays a key role in the metabolism of pro-atherogenic and anti-atherogenic lipoproteins affecting their plasma level as well as their physico-chemical properties. We hypothesized single nucleotide polymorphisms in the promoter region of the hepatic lipase gene to be associated with an increased risk for peripheral arterial disease (PAD).

METHODS

A total of 241 patients with PAD and 241 controls matched for sex and age (+/-2 years) were genotyped cross-sectionally for the --250 single nucleotide polymorphism in the hepatic lipase promoter. RESULTS. The frequency for the -250 A allele in patients with PAD was 0.203, whereas it was 0.147 in the controls (P=0.022). Hepatic lipase promoter polymorphism distribution remained significantly different between cases and controls after multivariate logistic regression analysis (P=0.021). The odds ratio of the -250 A hepatic lipase allele for the PAD was 1.69 (95% confidence interval of 1.08-2.64), when adjusted for current smoking, arterial hypertension, cholesterol, triglycerides, HbA(1C), total homocysteine and high sensitivity C-reactive protein.

CONCLUSION

Previous data in patients with ischaemic heart disease have suggested a pro-atherogenic role of low hepatic lipase levels. Our results extend these data to the vascular territory of the lower limbs, such that hepatic lipase promoter variation represents a genetic risk factor of PAD.

Genomic loci with pleiotropic effects on coronary artery calcification

We measured 381 genomewide markers and performed genetic linkage analyses in search of loci influencing coronary artery calcification (CAC), a measure of atherosclerosis determined by electron beam computed tomography, in 948 non-Hispanic white siblings (mean age [+/-standard deviation] = 59.6 +/- 9.9 years; 73.7% hypertensive). Measured risk factors for atherosclerosis included body mass index, pulse pressure, and high-density lipoprotein (HDL)-cholesterol. After adjustment for sex and age, the logarithm transformed measure of CAC was heritable (0.40 +/- 0.08, P < 0.0001) and genetically correlated with body mass index (0.28, P < 0.001), pulse pressure (0.36, P < 0.001), and HDL-cholesterol (-0.19, P < 0.001). Univariate linkage analysis demonstrated evidence of linkage for CAC, defined by maximum LOD scores (MLS) >or= 1.30, on chromosomes 1p, 4p, 5q, 7p, 13q, and 14q. Bivariate linkage analyses of CAC with each risk factor provided evidence of two regions with pleiotropic effects on CAC and HDL-cholesterol on chromosomes 4p16 (MLS=3.03, P = 0.00084) and 9q12 (MLS = 3.21, P = 0.00056), and of a region with pleiotropic effects on CAC and body mass index on chromosome 17p11 (MLS = 3.04, P = 0.00082). Inasmuch as the chromosome 9 and 17 regions were not detected in the univariate linkage analysis for CAC, multivariate linkage analyses of CAC and genetically correlated risk factors may help localize genes for coronary atherosclerosis.

Effect of hepatic lipase -514C->T polymorphism and its interactions with apolipoprotein C3 -482C->T and apolipoprotein E exon 4 polymorphisms on the risk of nephropathy in chinese type 2 diabetic patients

OBJECTIVE

Triglyceride-rich lipoprotein particles may promote the progression of diabetic nephropathy. Patients with diabetic nephropathy have increased plasma triglycerides and reduced activity of hepatic lipase (HL), which hydrolyzes triglycerides. We hypothesized that the HL -514C-->T polymorphism, which reduces HL expression, and its interactions with polymorphisms in apolipoprotein (apo) E and apoC3 increase the risk of diabetic nephropathy.

RESEARCH DESIGN AND METHODS

In a case-control study involving 374 Chinese type 2 diabetic patients with and 392 without diabetic nephropathy, we genotyped the HL -514C-->T, apoE exon 4, and apoC3 -482C-->T polymorphisms.

RESULTS

HL -514T-containing genotypes (T+) were associated with diabetic nephropathy (OR = 1.7, P = 0.0009). Adjustment by multiple logistic regression for hypertension, triglycerides, sex, non-HDL cholesterol, BMI, smoking, and alcohol intake did not diminish the association (OR = 1.8, P = 0.003). The association between HL T+ genotypes and diabetic nephropathy appeared stronger in diabetic patients with apoC3 -482 non-TT genotypes (OR = 1.9, P = 0.003) or apoE epsilon2 or epsilon4 alleles (OR = 2.2, P = 0.005). Subjects with HL TT exhibited trends toward increased triglyceride and non-HDL cholesterol levels compared with CC carriers.

CONCLUSIONS

HL T+ genotypes might increase the risk of developing diabetic nephropathy by slowing clearance of triglyceride-rich remnant lipoproteins. In concert with other risk factors (e.g., hyperglycemia), lipid abnormalities may damage the kidneys and endothelium, where reduced binding sites for lipases may precipitate a vicious cycle of dyslipidemia, proteinuria, and nephropathy.

Hepatic lipase: friend or foe and under what circumstances?

Hepatic lipase (HL) plays a role in the metabolism of chylomicron and very low-density lipoprotein remnants, low-density lipoproteins (LDL), and high-density lipoproteins (HDL), which are all implicated in atherosclerosis. Considering the effects of HL on these lipoproteins, it appears that HL has pro- as well as antiatherogenic potential. In line with clinical observations, most effects of HL on lipoprotein metabolism during hypertriglyceridemia may be interpreted as promoting atherosclerosis (formation of small, dense LDL, lowering of HDL levels), whereas most effects during hypercholesterolemia seem to be potentially antiatherogenic (stimulation of reverse cholesterol transport, clearing of intermediate-density lipoprotein). The potential modulation of pro- or antiatherogenics effect of HL by other factors, such as LDL receptor, cholesterol ester transfer protein, lipoprotein lipase, and ATP-binding cassette A-1 activity, is discussed.

The G-250A substitution in the promoter region of the hepatic lipase gene is associated with the conversion from impaired glucose tolerance to type 2 diabetes: the STOP-NIDDM trial

OBJECTIVES

Dyslipidaemia that includes high levels of triglycerides and low high-density lipoprotein cholesterol is a risk factor for type 2 diabetes. Hepatic lipase gene encoding a lipolytic enzyme participating in remodelling of plasma lipoproteins and formation of serum lipid profile is a promising candidate gene for type 2 diabetes. The purpose of the study was to investigate whether the G-250A promoter polymorphism of the LIPC gene predicts the conversion from impaired glucose tolerance (IGT) to type 2 diabetes.

SUBJECTS AND DESIGN

Study population comprised of subjects who participated in the STOP-NIDDM trial aiming to investigate the effect of acarbose compared with placebo on the prevention of type 2 diabetes in subjects with IGT.

RESULTS

Compared with subjects carrying the G-250G genotype, subjects with the A-250A genotype of the LIPC gene had a 2.35-fold [95% confidence interval (CI) 1.27-4.33, P = 0.006] higher risk of developing type 2 diabetes. Subjects in the placebo group and all women carrying the A-250A genotype had an especially high risk for the conversion to type 2 diabetes [odds ratio (OR) 2.74, 95% CI 1.14-6.61, P = 0.024 and OR 3.70, 95% CI 1.35-10.1, P = 0.011 respectively].

CONCLUSION

The G-250A promoter polymorphism of the LIPC gene is associated with an increased risk of development of type 2 diabetes in high-risk subjects with IGT. Therefore, genes regulating atherogenic dyslipidaemia are promising candidate genes for type 2 diabetes.

Dietary fat interacts with the -514C>T polymorphism in the hepatic lipase gene promoter on plasma lipid profiles in a multiethnic Asian population: the 1998 Singapore National Health Survey

We have previously reported an interaction between -514C>T polymorphism at the hepatic lipase (HL) gene and dietary fat on high-density lipoprotein-cholesterol (HDL-C) metabolism in a representative sample of white subjects participating in the Framingham Heart Study. Replication of these findings in other populations will provide proof for the relevance and consistency of this marker as a tool for risk assessment and more personalized cardiovascular disease prevention. Therefore, we examined this gene-nutrient interaction in a representative sample of Singaporeans (1324 Chinese, 471 Malays and 375 Asian Indians) whose dietary fat intake was recorded by a validated questionnaire. When no stratification by fat intake was considered, the T allele was associated with higher plasma HDL-C concentrations (P = 0.001), higher triglyceride (TG) concentrations (P = 0.001) and higher HDL-C/TG ratios (P = 0.041). We found a highly significant interaction (P = 0.001) between polymorphism and fat intake in determining TG concentration and the HDL-C/TG ratio (P = 0.001) in the overall sample even after adjustment for potential confounders. Thus, TT subjects showed higher TG concentrations only when fat intake supplied >30% of total energy. This interaction was also found when fat intake was considered as continuous (P = 0.035). Moreover, in the upper tertile of fat intake, TT subjects had 45% more TG than CC individuals (P < 0.01). For HDL-C concentration, the gene-diet interaction was significant (P = 0.015) only in subjects of Indian origin. In conclusion, our results indicate that there are differences in the association of -514C>T polymorphism with plasma lipids according to dietary intake and ethnic background. Specifically, the TT genotype is associated with a more atherogenic lipid profile when subjects consume diets with a fat content > 30%.

The -514 C->T hepatic lipase promoter region polymorphism and plasma lipids: a meta-analysis

Investigations of the -514 C-->T single nucleotide polymorphism (SNP) in the hepatic lipase (HL) gene promoter region (LIPC) have yielded contradictory results regarding its association with changes in plasma lipids. The current study is a meta-analysis of 25 publications on this SNP, comprising over 24,000 individuals, and its relationship with total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol (HDL), triglycerides, and HL activity. Significant decreases were observed in HL activity for both the CT and TT genotypes compared with the CC genotype [weighted mean difference (WMD), -5.83 mmol/liter.h (95% confidence interval, -8.48, -3.17) and -11.05 mmol/liter.h (95% confidence interval, -14.74, -7.36), respectively]. Moreover, significant increases in HDL were found; the CT to CC comparison showed an increase in WMD of 0.04 mmol/liter (95% confidence interval, 0.02, 0.05) mmol/liter, and the increase in the TT vs. CC difference was WMD of 0.09 mmol/liter (95% confidence interval, 0.07, 0.12). These changes appear to be stepwise, implying an allele dosage effect. All P values for these associations were less than 0.001. This meta-analysis demonstrates the importance of the -514C-->T SNP in determining HL activity and plasma HDL concentration and helps quantify the role that hepatic lipase plays in the metabolism of HDL.

Hepatic lipase, lipoprotein metabolism, and atherogenesis

The role of hepatic lipase as a multifunctional protein that modulates lipoprotein metabolism and atherosclerosis has been extensively documented over the last decade. Hepatic lipase functions as a lipolytic enzyme that hydrolyzes triglycerides and phospholipids present in circulating plasma lipoproteins. Hepatic lipase also serves as a ligand that facilitates lipoprotein uptake by cell surface receptors and proteoglycans, thereby directly affecting cellular lipid delivery. Recently, another process by which hepatic lipase modulates atherogenic risk has been identified. Bone marrow transplantation studies demonstrate that hepatic lipase present in aortic lesions markedly alters aortic lesion formation even in the absence of changes in plasma lipids. These multiple functions of hepatic lipase, which facilitate not only plasma lipid metabolism but also cellular lipid uptake, can be anticipated to have a major and complex impact on atherogenesis. Consistently, human and animal studies support proatherogenic and antiatherogenic roles for hepatic lipase. The concept of hepatic lipase as mainly a lipolytic enzyme that reduces atherogenic risk has evolved into that of a complex protein with multiple functions that, depending on genetic background and sites of expression, can have a variable effect on atherosclerosis.

Gender and Ethnic Differences in a Case-Control Study of Dyslipidemia: Using the Apolipoprotein A-V Gene as an Exemplar in Cardiovascular Genetics

Common, complex genetic disorders such as coronary heart disease (CHD) frequently show large population differences, contributing to health disparities. It is also well known that CHD risk factor profiles and the frequency of coronary events differ by gender. Study of premature CHD has revealed that apolipoproteins are important discriminating factors for distinguishing individuals with CHD. Recent findings indicated that apolipoprotein A-V (APOA-V) gene promoter polymorphisms are an important determinant of plasma triglycerides (TG) and lipoprotein cholesterol, and a risk factor for CHD. Variations in APOA-V may have varying impacts in different ethnic groups. The purpose of this interdisciplinary genetic research project was to determine (1) the association of the APOA-V polymorphisms with lipoprotein profiles, and (2) the gender and ethnic differences in the T-1131C promoter polymorphism of the APOA-V gene in individuals with dyslipidemia versus controls. Results indicate that the minor -1131C allele (CC homozygotes + CT heterozygotes) was associated with elevated plasma TG (p= 0.007), very low density lipoprotein (VLDL)–TG (p= 0.019), LDL-TG (p= 0.004), high-density-lipoprotein (HDL)-TG (p< 0.001), and VLDL-cholesterol (p= 0.008). We found a striking elevation in the frequency of the minor C allele in Asians (p< 0.001) compared to Europeans. We also found a significant difference in genotype frequency between men and women in Asians (p= 0.031) and Europeans (p< 0.01). Remarkably, Asian women with the C allele have a 36% increase in TG compared to Asian women homozygous for the T allele. In summary, we found significant ethnic-specific and gender-based differences in the frequency of the minor allele of the -1131 APOA-V gene promoter polymorphism. Identification of genetic variations among ethnic groups and between genders may have significant potential for a better understanding of the development of cardiovascular disease.

Genome-wide scan for quantitative trait loci influencing LDL size and plasma triglyceride in familial hypertriglyceridemia

Small, dense LDLs and hypertriglyceridemia, two highly correlated and genetically influenced risk factors, are known to predict for risk of coronary heart disease. The objective of this study was to perform a whole-genome scan for linkage to LDL size and triglyceride (TG) levels in 26 kindreds with familial hypertriglyceridemia (FHTG). LDL size was estimated using gradient gel electrophoresis, and genotyping was performed for 355 autosomal markers with an average heterozygosity of 76% and an average spacing of 10.2 centimorgans (cMs). Using variance components linkage analysis, one possible linkage was found for LDL size [logarithm of odds (LOD) = 2.1] on chromosome 6, peak at 140 cM distal to marker F13A1 (closest marker D6S2436). With adjustment for TG and/or HDL cholesterol, the LOD scores were reduced, but remained in exactly the same location. For TG, LOD scores of 2.56 and 2.44 were observed at two locations on chromosome 15, with peaks at 29 and 61 cM distal to marker D15S822 (closest markers D15S643 and D15S211, respectively). These peaks were retained with adjustment for LDL size and/or HDL cholesterol. These findings, if confirmed, suggest that LDL particle size and plasma TG levels could be caused by two different genetic loci in FHTG.

Hepatic lipase expression in macrophages contributes to atherosclerosis in apoE-deficient and LCAT-transgenic mice

Hepatic lipase (HL) has a well-established role in lipoprotein metabolism. However, its role in atherosclerosis is poorly understood. Here we demonstrate that HL deficiency raises the proatherogenic apoB-containing lipoprotein levels in plasma but reduces atherosclerosis in lecithin cholesterol acyltransferase (LCAT) transgenic (Tg) mice, similar to results previously observed with HL-deficient apoE-KO mice. These findings suggest that HL has functions that modify atherogenic risk that are separate from its role in lipoprotein metabolism. We used bone marrow transplantation (BMT) to generate apoE-KO and apoE-KO x HL-KO mice, as well as LCAT-Tg and LCAT-Tg x HL-KO mice, chimeric for macrophage HL gene expression. Using in situ RNA hybridization, we demonstrated localized production of HL by donor macrophages in the artery wall. We found that expression of HL by macrophages enhances early aortic lesion formation in both apoE-KO and LCAT-Tg mice, without changing the plasma lipid profile, lipoprotein lipid composition, or HL and lipoprotein lipase activities. HL does, however, enhance oxidized LDL uptake by peritoneal macrophages. These combined data demonstrate that macrophage-derived HL significantly contributes to early aortic lesion formation in two independent mouse models and identify a novel mechanism, separable from the role of HL in plasma lipoprotein metabolism, by which HL modulates atherogenic risk in vivo.

Hepatic lipase: a marker for cardiovascular disease risk and response to therapy

PURPOSE OF REVIEW

Hepatic lipase plays a key role in the metabolism of pro-atherogenic and anti-atherogenic lipoproteins affecting their plasma level as well as their physico-chemical properties. However, controversial evidence exists concerning whether hepatic lipase is pro or anti-atherogenic. The goal of this review is to summarize recent evidence that connects the enzyme to cardiovascular disease. The potential impact of genetic determinants of hepatic lipase activity in modulating both the development of coronary and carotid atherosclerosis will be discussed based on hepatic lipase proposed roles in lipoprotein metabolism.

RECENT FINDINGS

Twenty to 30% of individual variation of hepatic lipase activity is accounted for by the presence of a common polymorphism in the promoter region (-514 C to T) of the hepatic lipase gene (LIPC). This polymorphism, via its impact on hepatic lipase synthesis and activity, appears to contribute to (1) individual susceptibility to cardiovascular disease: the presence of the T allele (low hepatic lipase activity) may carry a marginally increased risk of atherosclerosis; (2) carotid plaque composition and individual susceptibility to cerebrovascular events: the presence of the C allele (high hepatic lipase activity) is associated with increased carotid intima-media thickness and abundance of macrophages in the carotid plaque (unstable plaque); and (3) response of cardiovascular disease patients to lipid-lowering therapy: patients with the CC genotype have the greatest clinical benefit from intensive lipid-lowering therapy.

SUMMARY

Convincing evidence shows that hepatic lipase plays a key role in remnant lipoprotein catabolism as well as in remodeling of LDL and HDL particles. The anti or pro-atherogenic role of hepatic lipase is likely to be modulated by the concurrent presence of other lipid abnormalities (i.e. increased LDL cholesterol levels) as well as by the genetic regulation of other enzymes involved in lipoprotein metabolism. Characterization of patients by their LIPC genotype will contribute to a better definition of individual risk of coronary and cerebrovascular events, specifically in patients with qualitative (small, atherogenic LDL and low HDL2 cholesterol) rather than quantitative lipid abnormalities for whom the routine lipid profile may underestimate the risk of coronary and cerebrovascular disease.

Acute regulation of hepatic lipase secretion by rat hepatocytes

Hepatic lipase is involved in cholesterol uptake by the liver. Although it is known that catecholamines are responsible for the daily variation of enzyme activity, the mechanisms involved are poorly understood. Rat hepatocytes incubated with adrenaline or other Ca(2+)-mobilizing hormones were used as an experimental model. Adrenaline reduced in a similar proportion the secretion of both hepatic lipase and albumin. The effect of adrenaline disappeared completely in cells exposed to cycloheximide. Adrenaline decreased incorporation of [35S]Met into cellular and secreted proteins, but it affected neither degradation of [35S]Met-prelabeled proteins nor the abundance of total and specific (albumin, hepatic lipase, beta-actin) mRNA. Other Ca(2+)-mobilizing agents had the opposite effect on hepatic lipase secretion: it was decreased by vasopressin but was increased by epidermal growth factor. Vasopressin and epidermal growth factor had the opposite effect on [35S]Met incorporation into cellular and secreted proteins, but neither affected hepatic lipase mRNA. The acute effect of adrenaline, vasopressin, and epidermal growth factor on hepatic lipase secretion is the consequence of the effect of these hormones on protein synthesis and is therefore nonspecific.

Cardiovascular disease genetics: a long and winding road

PURPOSE OF REVIEW

This review has two major goals. The first goal is to raise some of the methodological problems associated with studying the genetics of complex disorders, specifically cardiovascular diseases. The second is to update the reader with the most recent findings in the area of genotype-phenotype associations as well as the interaction between genetic factors and cardiovascular disease risk markers, with emphasis on those related to lipid metabolism.

RECENT FINDINGS

In terms of new information, three topics are presented: (1) new findings related to classical candidate genes, such as apolipoprotein E, cholesteryl ester transfer protein and hepatic lipase; (2) recent reports related to new loci that have joined the growing list of cardiovascular disease candidate genes (i.e. ATP-binding cassette transporters A1 and C6, peroxisome proliferator activated receptor alpha, interleukin-6); and (3) studies showing that multiple genes appear to be at the intersection of several age-related disorders such as cardiovascular disease, neurological disorders and osteoporosis (i.e. apolipoprotein E, vitamin D receptor, matrix Gla protein, peroxisome proliferator activated receptor gamma, angiotensin-converting enzyme, estrogen receptor, androgen receptor, methylenetetrahydrofolate reductase).

SUMMARY

The dramatic increase in our ability to carry out genotyping is creating a tremendous wealth of information in terms of associations between genetic markers and biochemical or clinical phenotypes. Increased attention, however, should be placed on study design and replication of findings. This should also be facilitated by the inclusion of multiple markers per loci in order to provide a more precise definition of the alleles associated with the phenotypes of interest. Moreover, given the fact that most of the phenotypes are equally affected by genetic and environmental factors, studies should emphasize the analyses of their interaction.

Hepatic lipase: a pro- or anti-atherogenic protein?

Hepatic lipase (HL) plays a role in the metabolism of pro- and anti-atherogenic lipoproteins affecting their plasma level and composition. However, there is controversy regarding whether HL accelerates or retards atherosclerosis. Its effects on different lipoprotein classes show that, potentially, HL may promote as well as decrease atherogenesis. Studies in animals with genetically modulated HL expression show that it depends on the model used whether HL acts pro- or anti-atherogenic. In humans, HL activity seems to correlate inversely with atherosclerosis in (familial) hypercholesterolemia, and positively in hypertriglyceridemia. In normolipidemia, HL activity is weakly associated with coronary artery disease (CAD). Genetically low or absent HL activity is usually associated with increased CAD risk, especially if plasma lipid transport is impaired due to other factors. Since HL promotes the uptake of lipoproteins and lipoprotein-associated lipids, HL may affect intracellular lipid content. We hypothesize that the prime role of HL is to maintain, in concert with other factors (e.g., lipoprotein receptors), intracellular lipid homeostasis. This, and the uncertainties about its impact on human atherosclerosis, makes it difficult to predict whether HL is a suitable target for intervention to lower CAD risk. First, the physiological meaning of changes in HL activity under different conditions should be clarified.