Influence of apolipoproteins on the anatomical distribution of arterial disease

Association of apolipoprotein levels with peripheral arterial disease: a meta-analysis of literature studies

AIMS

Lower limb peripheral artery disease (PAD) is a leading cause of atherosclerotic cardiovascular disease (ASCVD). Discordant data are available on the association between apolipoprotein and PAD. We performed a meta-analyses on the association between apolipoprotein (apo)B, apoA-I, and apoB/apoA-I ratio with PAD.

METHODS AND RESULTS

PubMed, Web of Science, Scopus databases were systematically searched. Studies providing data about apoB, apoA-I, apoB/apoA-I ratio in PAD subjects and non-PAD controls were included. Differences between PAD and non-PAD subjects were expressed as mean difference (MD) with pertinent 95% confidence intervals (95%CI). Twenty-two studies were included. Peripheral artery disease subjects showed higher apoB (MD: 12.5 mg/dL, 95%CI: 2.14, 22.87) and lower apoA-I levels (MD: -7.11 mg/dL, 95%CI: -11.94, -2.28) than non-PAD controls. Accordingly, ApoB/ApoA-I ratio resulted higher in PAD subjects than non-PAD controls (MD: 0.11, 95% CI: 0.00, 0.21). Non-HDL-C showed a direct association with the difference in apoB (z-value: 4.72, P < 0.001) and an inverse association with the difference of apoA-I (z-value: -2.43, P = 0.015) between PAD subjects and non-PAD controls. An increasing BMI was associated with an increasing difference in apoA-I values between PAD subjects and non-PAD controls (z-value: 1.98, P = 0.047).

CONCLUSIONS

Our meta-analysis suggests that PAD subjects exhibit increased apoB and reduced apoA-I levels, accompanied by an increased apoB/apoA-I ratio as compared with non-PAD controls.

The risk of cardiovascular events with increased apolipoprotein CIII: A systematic review and meta-analysis

BACKGROUND

Apolipoprotein CIII (apoC-III) is an atherogenic protein found on HDL, VLDL and LDL.

OBJECTIVE

The objective of this study is to review the literature on the association of blood apoC-III level with cardiovascular events and the dose-response relationship for this association.

METHODS AND RESULTS

MEDLINE, EMBASE, BIOSIS, CINAHL, Clinicaltrials.gov, grey-literature sources, contact with investigators, and reference lists of studies, without language restrictions, were reviewed. Twelve studies (5 retrospective and 7 prospective) with a total of 3163 cases of cardiovascular events met inclusion criteria for this systematic review. The pooled standardized mean difference showed significantly higher levels of apoC-III in the non-HDL fraction of plasma (representing apoC-III in VLDL and LDL) in those with cardiovascular disease compared with controls; no difference for apoC-III levels in HDL; and, a trend toward higher total plasma apoC-III in the cases. Pooled risk estimates from the meta-analysis were 2.48 (1.48-4.32; non-HDL apoC-III), 1.09 (0.65-1.82; HDL apoC-III), and 1.33 (1.07-1.66; total apoC-III) for a cardiovascular event with a 5-mg/dL increase in apoC-III.

CONCLUSIONS

The current body of literature includes several methodologically sound studies that together provide consistent evidence for an association of cardiovascular events with blood apoC-III level in total plasma or in VLDL and LDL. More data are needed to determine importance of levels of apoC-III in specific lipoproteins for cardiovascular risk assessment and management and to elucidate the interaction between triglycerides and apoC-III in relation to risk of cardiovascular disease.

The genetics of cerebrovascular atherosclerosis

Ischemic stroke attributable to atherosclerosis remains a major public health problem. Genetic factors are increasingly recognized as influencing risk for atherosclerosis directly and indirectly. Genetic makeup may influence the development of major vascular risk factors or alter susceptibility of the cerebral vasculature to these risk factors. More recently, newly identified risk factors for atherosclerosis, such as plasma homocysteine and infection, have also been reported to be influenced by important genetic determinants. This article reviews the current nature on genetics of cerebral and precerebral atherosclerosis and seeks to identify areas of promise for future clinical application.

Association of Cardiovascular Risk Factors with Pattern of Lower Limb Atherosclerosis in 2659 Patients Undergoing Angioplasty

OBJECTIVES

Aim of this study is to correlate distribution pattern of lower limb atherosclerosis with cardiovascular risk factor profile of patients with peripheral arterial occlusive disease (PAD).

PATIENTS AND METHODS

Analysis is based on a consecutive series of 2659 patients (1583 men, 1076 women, 70+/-11 years) with chronic PAD of atherosclerotic origin undergoing primary endovascular treatment of lower extremity arteries. Pattern of atherosclerosis was grouped into iliac (n=1166), femoropopliteal (n=2151) and infrageniculate (n=888) disease defined according to target lesions treated. A multivariable multinomial logistic regression analysis was performed to assess relation with age, gender and classical cardiovascular risk factors (diabetes mellitus, arterial hypertension, hypercholesterolemia, cigarette smoking) using femoropopliteal disease as reference.

RESULTS

Iliac disease was associated with younger age (RRR 0.95 per year of age, 95%-CI 0.94-0.96, p<0.001), male gender (RRR 1.32, 95%-CI 1.09-1.59, p=0.004) and cigarette smoking (RRR 2.02, 95%-CI 1.68-2.42, p<0.001). Infrageniculate disease was associated with higher age (RRR 1.02, 95%-CI 1.01-1.02, p<0.001), male gender (RRR 1.23, 95%-CI 1.06-1.41, p=0.005) and diabetes mellitus (RRR 1.68, 95%-CI 1.47-1.92, p<0.001). Hypercholesterolemia was less prevalent in patients with lesions below the knee (RRR 0.82, 95%-CI 0.71-0.94, p=0.006), whereas no distinct pattern was apparent related to arterial hypertension.

CONCLUSION

Clinical phenotype of peripheral atherosclerosis varies with prevalence of cardiovascular risk factors suggesting differences in mechanisms involved in iliac as compared with infrageniculate lesions. Identification of molecular mechanism might have influence on future therapeutic strategies in PAD patients.

Age-related effects of genetic variation on lipid levels: The Columbia University BioMarkers Study

OBJECTIVES

To examine the genotype:phenotype association in children compared with their parents.

METHODS

Variations at 4 key gene loci, namely lipoprotein lipase (LPL S447X), hepatic lipase (HL -480C>T), cholesteryl ester transfer protein (CETP TaqIB), and apolipoprotein CIII (APOC3 -455T>C and -482C>T), were examined in children (n = 495) and their parents (n = 353) in the Columbia University BioMarkers Study, 1994 to 1998.

RESULTS

The frequencies of the rare alleles of the HL -480C>T and APOC3 -455T>C and -482C>T (but not LPL S447X or CETP TaqIB) were significantly lower in non-Hispanic white participants compared with Hispanics. Overall, genotype effects seen in the adults were weaker in the children, although similar trends were seen. In an examination of the effect of body fat on the genotypic effects in the children, there was significant HL -480C>T:sum of skinfold interaction.

CONCLUSIONS

All genotypes were associated with clear relationships to plasma lipid levels in adults, but the effects were weaker in their children, unless stressed by body fat. atherosclerosis, cardiovascular disease, child, lipids, genetics.

Genetic association of five apolipoprotein polymorphisms with serum lipoprotein-lipid levels in African blacks

Genetic studies carried out mainly in European and European-derived populations have shown that common polymorphisms in genes coding for apolipoproteins are significant determinants of serum lipoprotein-lipid levels variation. However, except for a few sporadic studies, the distribution of apolipoprotein polymorphisms and their association with serum lipoprotein-lipid levels have not been evaluated systematically in African or African-derived populations. In this investigation we have studied five apolipoprotein polymorphisms, including APOA1/MspI-75 bp, APOA1/MspI+83 bp, APOC3/PvuII, APOE, and APOH in 786 Africans (493 men, 293 women) from Nigeria. The sample is comprised of Nigerian civil servants consisting of 462 junior staff (less affluent) and 324 senior staff (more affluent) where staff status is a correlate of their socioeconomic status. We first examined genetic associations in the total sample stratified by gender to determine the role of apolipoprotein polymorphisms in affecting serum lipid profile in the general population, and then by staff status to evaluate possible gene-environment interactions. In the total sample, the APOC3/PvuII polymorphism showed significant effect on HDL-cholesterol (P = 0.029) and HDL3-cholesterol (P = 0.009) in women, and the APOE polymorphism was significantly associated with total cholesterol (P = 0.031) and LDL-cholesterol (P = 0.0006) in women. Multiple regression analyses showed that the APOC3/PvuII polymorphism accounts for about 2 and 3% of the variation in HDL-cholesterol and HDL3-cholesterol, respectively, in women; while the APOE polymorphism accounted for about 5 and 6% of the variation in total- and LDL-cholesterol, respectively, in women. Whereas the association of the APOE polymorphism was independent of the staff status, the significant affect of the APOC3/PvuII polymorphism on HDL- and HDL3-cholesterol was confined to senior staff women where it explained about 7% of their variation. We also observed an interaction between staff and the APOH polymorphism in affecting cholesterol levels. The APOH polymorphism showed significant association with total cholesterol (P = 0.010) and LDL-cholesterol (P = 0.016) in senior staff women and explained about 7 and 5% of their phenotypic variations, respectively. These data indicate that gene-environment interaction may play an important role in affecting serum lipid profile in African populations.

Carotid atherosclerosis in patients operated for lower extremity ischemia before the age of 50: a case control study

The purpose of this study was to investigate the presence of, and to identify factors associated with carotid atherosclerosis in patients, previously operated on for lower extremity ischemia before the age of 50. Forty-eight patients were compared to sex- and age-matched controls. All subjects were examined with duplex ultrasonography of the neck arteries and analysis of serum lipoproteins. History including smoking habits, family history of cardiovascular disease, and medication was also obtained. The patients were examined clinically and their preoperative angiograms were reevaluated. Thirty-one patients (64%) and 13 controls (23%) had a carotid lesion (p < 0.0001). Patients with suprainguinal or multilevel disease had a higher proportion of carotid lesions than those with only infrainguinal disease in whom the proportion was similar to the controls. A multiple regression analysis among the patients revealed that age, level of lower extremity arterial disease, presence of family history, and the ratio apolipoproteinB/apolipoproteinA discriminated significantly between those with and without carotid disease. It is concluded that a high proportion of patients operated on for lower extremity suprainguinal arterial occlusive disease at an early age have carotid lesions at follow-up, while patients operated on due to isolated infrainguinal disease have a prevalence similar to controls.

Arterial Damage, Triglycerides, Apolipoprotein, and Lp-(a) Values in PVD Patients

The aim of the study was to provide a detailed apolipoproteic profile in stage II peripheral vascular disease (PVD) patients and to ascertain whether lower ankle/ arm pressure index (API) values were associated with a worse profile.

Apolipoproteins of 83 stage II PVD patients (average age 64.7 ± 9.3 years) were selected and compared with those of a group of 44 normal control subjects, similar in terms of age, sex, and smoking and eating habits. Neither PVD patients nor controls had ever received lipid-lowering agents or defined dietary treatment. A diagnosis of PVD was confirmed by an API of <0.85. Arteriopathic patients were also split into two groups, depending on their API values, similar in terms of age, sex and smoking habits: API values of one group (n = 38) were ≥0.6, those of the other group (n = 45) were <0.6. The following biohumoral parameters were considered: fasting glycemia, total cholesterol, triglycerides (TGs); high-density lipoprotein cholesterol (HDL-C); low density lipoprotein cholesterol (LDL-C), very low density lipoprotein cholesterol (VLDL-C), total cholesterol (TC)/HDL-C (TC/ HDL-C), Apoproteins (Apos) AI, AII, B, CII, CIII, and E; and lipoprotein a [Lp(a)].

HDL-C and Apo AI were lower ( p < 0.01), while TC/ HDL-C ratios, Apo B, and Apo CII were higher ( p < 0.01) in PVD patients compared with controls. The comparison between the two PVD groups with different API values showed higher blood TG and VLDL-C values for the patients with lower API values (p < 0.05), indicating a relationship between hypertriglyceridemia and greater arterial damage. Key Words: Peripheral arterial occlusive disease-Triglyceride-Lipoprotein a.

The influence of smoking cessation and hypertriglyceridaemia on the progression of peripheral arterial disease and the onset of critical ischaemia

OBJECTIVE

To investigate whether smoking and other cardiovascular risk factors were associated with deterioration of ankle/brachial pressure index or onset of critical ischaemia in patients with mild to moderate intermittent claudication.

DESIGN AND SETTING

Longitudinal study in a London teaching hospital.

SUBJECTS

415 consecutive smokers, with symptoms of intermittent claudication and an ankle/brachial pressure index of <0.9, referred for a surgical opinion between April 1985 and December 1990, who were not considered for an immediate surgical procedure.

MAIN OUTCOME RESULTS

Reduction in ankle/brachial pressure index of >0.14, onset of critical limb ischaemia.

RESULTS

After one year of follow up 183 patients (44%) had stopped smoking (as evaluated by biochemical markers). With longer follow up only 110 patients (27%) had maintained smoking cessation. There were no differences in age, sex, and previous tobacco exposure between stoppers and smokers, but the proportion of diabetics among stoppers (20%) was greater than among those who continued smoking (10%) [p=0.01]. The annual rate of deterioration of ABPI was 21, 16 and 17% respectively in the first, second and third year of follow-up and the onset of critical ischaemia was observed in 52 patients (12.5%) during the period of follow-up. In univariate analyses, continued smoking, diabetes and presence of ischaemic heart disease were not associated with an increased risk of deterioration of ABPI, but hypertriglyceridaemia (> or = 2.2 mmol/l) was, [relative risk 1.7(95% CI 1.21-2.37), p=0.003], and patients having systolic blood pressure in the middle tertile (153-170 mmHg had a reduced risk of deterioration of ABPI, p=0.026. Hypertriglyceridaemia (> or = 2.2mmol/l) was the only independent factor associated with deterioration of ABPI in multivariate analysis [relative risk 1.8(95% CI:1.23-2.59), p=0.003] and also was associated with a relative risk of onset of critical ischaemia of 1.9 [(95% CI: 1.08-2.87), p=0.035], compared with triglyceride levels of <2.2mmol/l.

CONCLUSION

For those with mild to moderate claudication, the lack of immediate benefit from cessation of smoking appears to be associated with a gradual return to smoking. Hypertriglyceridaemia was identified as the most important independent factor associated with the progression of peripheral arterial disease and onset of critical ischaemia.

Genetic basis of variation in carotid artery wall thickness

BACKGROUND AND PURPOSE

Other than the documented associations of risk factors and carotid artery wall thickness, the genetic basis of variation in carotid artery intimal-medial thickness (IMT) is unknown. The purpose of this study was to examine the extent to which variation in common carotid artery (CCA) IMT and internal carotid artery (ICA) IMT are under genetic control.

METHODS

The sibship data used for this analysis were part of an epidemiological survey in Mexico City. The CCA and ICA analyses were based on 46 and 44 sibships of various sizes, respectively. The CCA and ICA IMTs were measured with carotid ultrasonography. Using a robust variance decomposition method, we performed genetic analyses of CCA IMT and ICA IMT measurements with models incorporating several cardiovascular risk factors (eg, lipids, diabetes, blood pressure, and smoking) as covariates.

RESULTS

After accounting for the effects of covariates, we detected high heritabilities for CCA IMT (h2 = 0.92 +/- 0.05, P = .001) and ICA IMT (h2 = 0.86 +/- 0.13, P = .029). Genes accounted for 66.0% of the total variation in CCA IMT, whereas 27.7% of variation was attributable to covariates. For ICA IMT, genes explained a high proportion (74.9%) of total phenotypic variation. The covariates accounted for 11.5% of variation in ICA IMT.

CONCLUSIONS

Our results suggest that substantial proportions of phenotypic variance in CCA IMT and ICA IMT are attributable to shared genetic factors.

Variation in cardiovascular risk factors by angiographic site of lower limb atherosclerosis

OBJECTIVE

To determine differences in the levels of the cardiovascular risk factors, cigarette smoking, serum lipids and blood pressure, between three groups of patients with different sites of lower limb atherosclerosis.

DESIGN

Cross-sectional survey of a consecutive series of patients with symptoms of either intermittent claudication or rest pain.

METHODS AND MATERIALS

One hundred and ninety-two men and women who had undergone angiography were classified using the Bollinger scoring system into groups with predominantly aortoiliac, femoropopliteal or dual-site disease. History of cigarette smoking, serum cotinine, serum thiocyanate, total cholesterol and HDL cholesterol were estimated. Systolic and diastolic pressures were measured and the ankle brachial pressure index (ABPI) was calculated.

RESULTS

Eighty-five patients were classified as having femoropopliteal disease, 34 aortoiliac disease and 73 dual-site disease. After adjusting for age, sex and severity of disease, aortoiliac patients were significantly younger (p </- 0.001), more likely to be female and current smokers, and had the highest levels of diastolic blood pressure. Life time cigarette consumption (pack-years) and total cholesterol concentrations were highest in femoropopliteal disease. Patients with dual-site disease were more likely to have had a myocardial infarction and angina pectoris (p </- 0.05). Systolic blood pressure was also highest in this group.

CONCLUSION

different levels of cardiovascular risk factors may predispose individuals to atherosclerosis at different sites in the lower limb. Large population studies would be required to delineate the risks more precisely.

Association between genetic variation at the APO AI-CIII-AIV gene cluster and familial combined hyperlipidaemia

By using chemical cleavage mismatch analysis and the single strand conformation polymorphism technique, DNA fragments of the apo CIII gene, including the 5' flanking region and all the exons, were screened for sequence changes underlying the observed association between familial combined hyperlipidaemia (FCHL) and the apo AI-CIII-AIV gene cluster in affected individuals from eight FCHL families. A C1100-T transition in the wobble position of codon 14 in exon 3 and a T3206-G transversion in the non-translated region of exon 4 were identified, occurring in four and all probands, respectively. Using these variants and the G-75-A transition in the apo AI promoter, co-segregation of the gene cluster with hyperlipidaemia could be excluded in all eight families (lod score - infinity at theta = 0). No support for co-segregation was obtained using the affected pedigree member method of linkage analysis (overall T = -0.77 for f(p) = 1 [symbol: see text] p). The frequencies of T1100 and G3206 in a group of 55 patients with combined hyperlipidaemia were 0.35 and 0.52, respectively, which were significantly higher compared to 360 controls (0.21, p < 0.01 and 0.35, p < 0.005 respectively). In patients homozygous for the T1100 allele, levels of plasma triglyceride were 2.5-fold higher (868 mg/dl) than those homozygous for the C1100 allele (337 mg/dl), while patients heterozygous for the polymorphism had intermediate values (443 mg/dl) (p < 0.01). A similar association was seen in controls (p < 0.04). The three polymorphisms studied were in strong linkage disequilibrium in both the group of CHL patients and the unrelated individuals. This study confirms the association between common variation in the gene cluster and differences in plasma lipid levels in the general population and in patients with combined hyperlipidaemia, but fails to confirm co-segregation with FCHL, suggesting the role of other genetic or environmental factors in the aetiology of FCHL.

Associations of genotypes at the apolipoprotein AI-CIII-AIV, apolipoprotein B and lipoprotein lipase gene loci with coronary atherosclerosis and high density lipoprotein subclasses

Association studies were carried out in a sample of 86 patients from Sweden who had survived a myocardial infarction (MI) at a young age and 93 age-matched healthy individuals, to compare the impact of polymorphisms at the apolipoprotein (apo) AI-CIII-AIV gene cluster on among-individual differences in plasma lipid and lipoprotein traits, the five high density lipoprotein (HDL) subclasses (2b to 3c), lipoprotein lipase (LPL) activity and presence and progression of atherosclerosis. Individuals were genotyped for four polymorphisms; 5'apoAI (G/A-75), 3'apoAI (PstI; P +/-), apoCIII (C/T1100) and apoCIII (PvuII; V +/-), using PCR-based techniques. Allele frequencies were similar in healthy individuals and patients (frequencies of alleles in combined population: 5'apoAI-A-75 = 0.14, 3'apoAI-P- = 0.05, apoCIII-T1100 = 0.27 and apoCIII-V- = 0.18). In the healthy individuals, levels of low density lipoprotein (LDL) triglycerides were significantly associated with genotypes of the apoCIII-PvuII polymorphism (p = 0.02), but no other associations were found between lipids or HDL subclasses and single polymorphisms in the apoAI-CIII-AIV gene cluster. Levels of triglycerides and very low density lipoprotein (VLDL) triglycerides were significantly higher in the presence of the haplotype defined by the presence of apoCIII-T1100 and common alleles of the other three polymorphisms, explaining 5.8% and 7.8% (p = 0.03 and 0.01), respectively, of sample variance. In the patients, no associations were found between lipids or HDL subclasses and variation at the apoAI-CIII-AIV gene cluster. Associations were also examined between levels of HDL subclasses and variation at the apoE (common isoforms), apoB (signal peptide and XbaI polymorphisms) and lipoprotein lipase (PvuII, HindIII and Serine447/Stop polymorphisms) gene loci. In the patient group only, levels of protein in HDL2b, HDL2a and HDL3b subclasses were significantly associated with genotypes of the LPL-HindIII polymorphism (22.1, 19.3 and 11.4%, respectively, of sample variance; p < 0.05). Finally, associations were examined between genotypes at the apoAI-CIII-AIV gene cluster and the extent of coronary atherosclerosis. Global severity of atherosclerosis at the first angiography was weakly associated with genotypes of the apoCIII-C/T1100 polymorphism, presence of the T1100 allele being associated with 53% lower median score (1.6 vs 0.75; p = 0.09).(ABSTRACT TRUNCATED AT 400 WORDS)

Are cerebral aneurysms atherosclerotic?

BACKGROUND AND PURPOSE

The aim of our study was to investigate plasma and genetic risk factors for rupture of cerebral aneurysms.

METHODS

In London, a case-control study was made of 56 consecutive patients admitted to a regional neurosurgical service for treatment of ruptured cerebral aneurysm and of 93 control subjects. A further 40 consecutive patients admitted in Arhus with ruptured cerebral aneurysm also were studied.

RESULTS

The British case-control study showed that smoking was associated with an increased risk of ruptured cerebral aneurysm (odds ratio, 9.1; 95% confidence interval [CI], 3.4 to 23.8; P < .001 for a history of > 10 pack years). After age and sex adjustment, factors associated with ruptured cerebral aneurysm included a cholesterol concentration in the highest tertile (> or = 6.3 mmol/L; odds ratio, 10.2; 95% CI, 3.9 to 26.7; P < .001), an apolipoprotein B concentration in the highest tertile (> or = 0.84 g/L; odds ratio, 6.4; 95% CI, 2.5 to 16.3; P < .001), and concentrations of HDL cholesterol in the lowest tertile (< 1.1 mmol/L; odds ratio, 3.6; 95% CI, 1.4 to 8.2; P < .01). History of hypertension was of less importance (odds ratio, 4.0; 95% CI, 1.41 to 11.7; P < .01). Smoking history (P < .001) and increased concentrations of cholesterol (P < .0001) were the most important independent risk factors associated with ruptured cerebral aneurysm on multivariate analysis. The histories of hypertension and smoking, together with apolipoprotein B levels, in the Danish patients were similar to those in the British patients. In the entire patient group, the frequencies of two polymorphic variations in the type III collagen gene and polymorphisms at the apolipoprotein B, apolipoprotein C-III, and haptoglobin gene loci were not different from control subjects or the normal population; allele frequencies in British and Danish patients were similar.

CONCLUSIONS

An atherosclerotic profile including increased total cholesterol concentration and a long smoking history may contribute to the rupture of cerebral aneurysms. This study provides no support for the hypothesis that inherited abnormalities of type III collagen are a common cause of cerebral aneurysms.

Segmental arterial disease in the lower extremities: correlates of disease and relationship to mortality

The purpose of this study was to identify the correlates of disease and mortality risk associated with the presence of stenosis in the major arterial segments of the lower limb in men and women evaluated in a peripheral vascular laboratory. A total of 326 men and 249 women had unisegmental stenosis; 312 men and 275 women had multisegmental disease; 132 men and 111 women had no apparent disease. Multivariate analysis indicated that current smoking and elevated systolic blood pressure were the key risk factors associated with isolated aortoiliac and femoropopliteal arterial disease in both men and women. A history of diabetes was significantly associated with tibioperoneal disease in men while elevated systolic blood pressure was the major correlate of distal disease in women in this patient population. The relative risk of mortality was elevated 2- to 7-fold in men and women with multi- and unisegmental disease involving the aortoiliac and femoropopliteal segments; presence of tibioperoneal disease did not significantly increase mortality relative to those who were free of disease. These results suggest that the etiology and mortality risk associated with atherosclerosis in the lower extremity may vary with the anatomic site and/or severity of the lesion.