Associations of genetic polymorphisms of arachidonate 5-lipoxygenase-activating protein with risk of coronary artery disease in a European–American population

Predictive capacity of a genetic risk score for coronary artery disease in assessing recurrences and cardiovascular mortality among patients with myocardial infarction

Aim

This study aimed to evaluate the capacity of a genetic risk score (GRS) for coronary artery disease (CAD) independent of classical cardiovascular risk factors to assess the risk of recurrence in patients with first myocardial infarction. The secondary aim was to determine the predictive value of this GRS.

Methods

We performed a meta-analysis of individual data from three studies, namely, a prospective study including 75 patients aged <55 years, a prospective study including 184 patients with a mean age of 60.5 years, and a case-control study (77 cases and 160 controls) nested in a cohort of patients with first myocardial infarction. A GRS including 12 CAD genetic variants independent of classical cardiovascular risk factors was developed. The outcome was a composite of cardiovascular mortality and recurrent acute coronary syndrome.

Results

The GRS was associated with a higher risk of recurrence [hazard ratio = 1.24; 95% confidence interval (CI): 1.04-1.47]. The inclusion of the GRS in the clinical model did not increase the model's discriminative capacity (change in C-statistic/area under the curve: 0.009; 95% CI: -0.007 to 0.025) but improved its reclassification (continuous net reclassification index: 0.29; 95% CI: 0.08-0.51).

Conclusion

The GRS for CAD, independent of classical cardiovascular risk factors, was associated with a higher risk of recurrence in patients with first myocardial infarction. The predictive capacity of this GRS identified a subgroup of high-risk patients who could benefit from intensive preventive strategies.

Relationship between Arachidonate 5-Lipoxygenase-Activating Protein Gene and Peripheral Arterial Disease in Elderly Patients Undergoing General Surgery: A Retrospective Observational Study

Patients with peripheral arterial disease (PAD) are at a higher risk of developing postoperative complications. Arachidonate 5-lipoxygenase-activating protein (ALOX5AP) plays an important role in atherosclerosis pathogenesis. In this study, the relationship between PAD and several single nucleotide polymorphisms (SNPs) of ALOX5AP (rs17216473, rs10507391, rs4769874, rs9551963, rs17222814, and rs7222842) was investigated in elderly patients undergoing general surgery. The medical records of 129 patients aged > 55 years who underwent elective general surgery between May 2018 and August 2019 were retrospectively reviewed. The A/A in rs17216473, A/A in rs10507391, G/G in rs4769874, and A/A in rs9551963 were calculated as 0 points and the rest as 1 point to define the genetic risk score. The prevalence of PAD tended to increase with higher genetic risk scores (patients had less ALOX5AP gene polymorphism of A/A in rs17216473, A/A in rs10507391, G/G in rs4769874, or A/A in rs9551963) (p = 0.005). Multivariate logistic regression analysis revealed that the genetic risk score (p = 0.009) and age (p = 0.007) were positively correlated with the prevalence of PAD. Genetic polymorphisms of ALOX5AP and age were associated with the prevalence of PAD in this study.

A genetic risk score predicts recurrent events after myocardial infarction in young adults

INTRODUCTION AND OBJECTIVES

To evaluate whether a genetic risk score (GRS) improves prediction of recurrent events in young nondiabetic patients presenting with an acute myocardial infarction (AMI) and identifies a more aggressive form of atherosclerosis.

METHODS

We conducted a prospective study with consecutive nondiabetic patients aged <55 years presenting with AMI. We performed a genetic test, cardiac computed tomography, and analyzed several biomarkers. We studied the association of a GRS composed of 11 genetic variants and a primary composite endpoint (cardiovascular mortality, a recurrent event, and cardiac hospitalization).

RESULTS

A total of 81 patients were studied and followed up for a median of 4.1 years. There were 24 recurrent cardiovascular events. Compared with the general population, study participants had a higher prevalence of 9 out of 11 risk alleles. The GRS was significantly associated with recurrent cardiovascular events, especially when baseline low-density lipoprotein cholesterol (LDL-C) levels were elevated. Compared with the low-risk GRS tertile, the multivariate-adjusted HR for recurrences was 10.2 (95%CI, 1.1-100.3; P=.04) for the intermediate-risk group and was 20.7 (2.4-181.0; P=.006) for the high-risk group when LDL-C was≥2.8mmol/L (≥ 110mg/dL). Inclusion of the GRS improved the C-statistic (ΔC-statistic=0.086), cNRI (continuous net reclassification improvement) (30%), and the IDI (integrated discrimination improvement) index (0.05). Cardiac computed tomography frequently detected coronary calcified atherosclerosis but had limited value for prediction of recurrences. No association was observed between metalloproteinases, GRS and recurrences.

CONCLUSIONS

A multilocus GRS may identify individuals at increased risk of long-term recurrences among young nondiabetic patients with AMI and improve clinical risk stratification models, particularly among patients with high baseline LDL-C levels.

Genetic variation in the leukotriene pathway is associated with myocardial infarction in the Chinese population

Background

Genetic variation in the genes ALOX5 (arachidonate 5-lipoxygenase), ALOX5AP (arachidonate 5-lipoxygenase-activating protein) and LTA4H (leukotriene A4 hydrolase) has previously been shown to contribute to the risk of MI (myocardial infarction) in Caucasian and African American populations. All genes encode proteins playing a role in the synthesis of the pro-inflammatory leukotriene B mediators, possibly providing a link between MI and inflammation. The aim of the present study was to investigate whether these associations could be confirmed in the study of China MI patients. The study included 401 Han Chinese MI patients and 409 controls. Six tag single nucleotide polymorphisms (SNPs)—ALOX5 rs12762303 and rs12264801, ALOX5AP rs10507391, LTA4H rs2072512, rs2540487 and rs2540477—were selected. SNP genotyping was performed by an improved multiplex ligation detection reaction assay.

Results

The rs2540487 genotype was associated with the risk of MI in overdominant model (P = 0.008). rs12762303 and rs10507391 SNPs were significantly associated with lipid levels in MI patients (P < 0.006–0.008). Several SNPs interacted with alcohol consumption, cigarette smoking, and hypertension to modify TC, TG, LDL-C and CRE levels, and the risk of MI (P < 0.0017 for all). No association between the SNPs of LT pathway and susceptibility to MI was found (P > 0.05 for all).

Conclusions

Taken together, this study provides additional evidence that functional genetic variation of the LT pathway can mediate atherogenic processes and the risk of MI in Chinese.

Weighted Multi-marker Genetic Risk Scores for Incident Coronary Heart Disease among Individuals of African, Latino and East-Asian Ancestry

We examined the clinical utility of two multi-locus genetic risk scores (GRSs) previously validated in Europeans among persons of African (AFR; n = 2,089), Latino (LAT; n = 4,349) and East-Asian (EA; n = 4,804) ancestry. We used data from the GERA cohort (30-79 years old, 68 to 73% female). We utilized two GRSs with 12 and 51 SNPs, respectively, and the Framingham Risk Score (FRS) to estimate 10-year CHD risk. After a median 8.7 years of follow-up, 450 incident CHD events were documented (95 in AFR, 316 in LAT and 39 EA, respectively). In a model adjusting for principal components and risk factors, tertile 3 vs. tertile 1 of GRS_12 was associated with 1.86 (95% CI, 1.15-3.01), 1.52 (95% CI, 1.02-2.25) and 1.19 (95% CI, 0.77-1.83) increased hazard of CHD in AFR, LAT and EA, respectively. Inclusion of the GRSs in models containing the FRS did not increase the C-statistic but resulted in net overall reclassification of 10% of AFR, 7% LAT and EA and in reclassification of 13% of AFR and EA as well as 10% LAT in the intermediate FRS risk subset. Our results support the usefulness of incorporating genetic information into risk assessment for primary prevention among minority subjects in the U.S.

Common Polymorphisms in the 5-Lipoxygenase Pathway and Risk of Incident Myocardial Infarction: A Danish Case-Cohort Study

BACKGROUND

The 5-lipoxygenase pathway (5-LOX) has been implicated in the development of cardiovascular disease and studies have suggested that genetic polymorphisms related to key enzymes in this pathway may confer risk of myocardial infarction (MI). This study investigated the association of pre-selected genetic polymorphisms in four candidate genes of 5-LOX (arachidonate 5-lipoxygenase and its activating protein (ALOX-5 and FLAP), leukotriene A4 hydroxylase (LTA4-H) and leukotriene C4 synthase (LTC4-S)) with incident MI.

METHODS

In a Danish cohort including 57,053 participants, aged 50-64 at enrolment and recruited from 1993-97, we conducted a case-cohort study including cases with incident MI and a randomly selected sub cohort of 3,000 participants. Cases were identified from national registries through July 2013. A total of 22 SNPs were selected and genotyped using the commercially available KASP™ assay. A tandem-repeat polymorphism, located in the ALOX-5 gene, was genotyped by multi-titre plate sequencing. Haplotypes were inferred using PHASE 2.1.

RESULTS

During a median follow-up of 17.0 years we identified 3,089 cases of incident MI. In FLAP, two SNPs were negatively associated with incident MI (rs9551963 & rs17222842) while one SNP (rs2247570) located in LTA4-H, was associated with higher risk of MI when comparing subjects with two copies of the variant allele to homozygotes for the wild type. However, only rs17222842 remained significantly associated with MI after correcting for multiple testing. Furthermore, the promoter polymorphism rs59439148 was associated with risk of MI in men. For male carriers of two variant alleles we found a hazard ratio of 1.63 (95% CI: 1.06;2.52) compared to homozygotes for the wild type. Previously described haplotypes (Hap-A -B, -E and -K) were not associated with MI in our population.

CONCLUSION

In conclusion, some common polymorphisms in the 5-lipoxygenase pathway were modestly associated with incident MI, suggesting a potential role for this pathway in the development of cardiovascular disease.

Clinical Utility of Multimarker Genetic Risk Scores for Prediction of Incident Coronary Heart Disease: A Cohort Study Among Over 51 000 Individuals of European Ancestry

BACKGROUND

We evaluated whether including multilocus genetic risk scores (GRSs) into the Framingham Risk Equation improves the predictive capacity, discrimination, and reclassification of asymptomatic individuals with respect to coronary heart disease (CHD) risk.

METHODS AND RESULTS

We performed a cohort study among 51 954 European-ancestry members of a Northern California integrated healthcare system (67% female; mean age 59) free of CHD at baseline (2007-2008). Four GRSs were constructed using between 8 and 51 previously identified genetic variants. After a mean (±SD) follow-up of 5.9 (±1.5) years, 1864 incident CHD events were documented. All GRSs were linearly associated with CHD in a model adjusted by individual risk factors: hazard ratio (95% confidence interval) per SD unit: 1.21 (1.15-1.26) for GRS_8, 1.20 (1.15-1.26) for GRS_12, 1.23 (1.17-1.28) for GRS_36, and 1.23 (1.17-1.28) for GRS_51. Inclusion of the GRSs improved the C statistic (ΔC statistic =0.008 for GRS_8 and GRS_36; 0.007 for GRS_12; and 0.009 for GRS_51; all P<0.001). The net reclassification improvement was 5% for GRS_8, GRS_12, and GRS_36 and 4% for GRS_51 in the entire cohort and was (after correcting for bias) 9% for GRS_8 and GRS_12 and 7% for GRS_36 and GRS_51 when analyzing those classified as intermediate Framingham risk (10%-20%). The number required to treat to prevent 1 CHD after selectively treating with statins up-reclassified subjects on the basis of genetic information was 36 for GRS_8 and GRS_12, 41 for GRS_36, and 43 for GRS_51.

CONCLUSIONS

Our results demonstrate significant and clinically relevant incremental discriminative/predictive capability of 4 multilocus GRSs for incident CHD among subjects of European ancestry.

Elevated levels of leukotriene B4 and thromboxane B2 distinguish chest pain of cardiac and non cardiac origin

OBJECTIVE

Myocardial infarction (MI) is often preceded by severe chest pain. The use of inflammatory markers to distinguish between chest pain of cardiac and non cardiac origin are not well reported. The aim of the study was to distinguish the chest pain of non cardiac and cardiac origin by using reliable inflammatory markers.

METHODS

The present study enrolled 80 subjects including chest pain which lead to myocardial infarction (n=40), non-cardiac chest pain (CP) patients (n=20) and healthy volunteers (N) (n=20). Leukotriene B4 (LTB4) and thromboxane B2 (TXB2) levels were analyzed along with hs-CRP.

RESULTS

Receiver operating characteristic (ROC) curve analysis showed LTB4 and TXB2 to be a good discriminator between patients with chest pain of cardiac and non cardiac in origin. The area under the curve was found to be 0.988 and 0.925 for LTB4 and TXB2, respectively when compared with hs-CRP. The sensitivity and specificity of LTB4 and TXB2 were found to be 90, 85% and 95, 90%, respectively.

CONCLUSION

The measurement of LTB4 and TXB2 levels may therefore be useful to distinguish the chest pain leading to MI from that of non cardiac in origin and for the management of the disease.

Leukotriene A4 hydrolase haplotype, diet and atherosclerosis: a twin study

OBJECTIVE

Atherosclerosis is an inflammatory process resulting from the interaction between genetic and environmental factors. Leukotrienes are inflammatory mediators generated from arachidonic acid, and genetic polymorphisms involved in leukotriene metabolism are implicated in atherosclerosis. The objectives of this study are to examine whether genetic variants in key leukotriene enzymes are associated with atherosclerosis, and whether dietary intake of competing leukotriene substrates modifies the effect of leukotriene variants on atherosclerosis.

METHODS

Atherosclerosis was assessed by common carotid intima-media thickness (IMT) using ultrasound. Sequence variants within arachidonate 5-lipoxygenase activating protein (ALOX5AP) and leukotriene A4 hydrolase (LTA4H) genes were analyzed with 32 single nucleotide polymorphisms (SNPs) in 169 Caucasian twin pairs from the Vietnam Era Twin Registry. The associations between genetic polymorphisms and carotid atherosclerosis, and gene × diet interactions were examined by generalized estimating equation controlling for potential confounders.

RESULTS

A six-SNP haplotype in LTA4H, designated HapE, was significantly associated with carotid IMT after adjusting for known coronary risk factors. Twins carrying HapE had a much lower IMT compared to twins not carrying (695 μm vs. 750 μm, p = 0.0007). Moreover, dietary intake of polyunsaturated fatty acids strongly augmented the cardioprotective effect of HapE among those with this haplotype but not those without, suggesting a haplotype × diet interaction (interaction P(HapE×n-3) = 0.03, P(HapE×n-6) = 0.015).

CONCLUSION

We identified a novel leukotriene haplotype that appears to be protective toward subclinical atherosclerosis. This association is modified by dietary intake of polyunsaturated fatty acids.

Variants of arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene and risk of coronary heart disease: A meta-analysis

BACKGROUND AND AIMS

Previous studies indicated that the arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene polymorphisms are associated with risk of coronary heart disease (CHD). However, other studies have yielded contradictory results. This meta-analysis investigated the relationship between variants of arachidonate 5-lipoxygenase-activating protein (ALOX5AP) gene and CHD.

METHODS

We identified all studies published before January 2010 through computer-based searches of PubMed, EMBASE, Google Scholar databases, and CNKI (Chinese National Knowledge Infrastructure). Data were extracted by two authors and pooled odds ratio (OR) and 95% confidence interval (CI) were calculated.

RESULTS

In this meta-analysis, HapA haplotype (rs17222814G-rs10507391T-rs4769874G-rs9551963A) was associated with myocardial infarction (MI) (OR = 1.37, 95% CI: 1.02-1.82). Regarding the HapB haplotype (rs17216473A-rs10507391A- rs9315050A- rs17222842G), there was a significant association with CHD (OR = 1.33, 95% CI: 1.10-1.62). For the rs17222814, rs10507391, rs4769874, rs9551963, rs17216473, rs9315050 and rs9579646 polymorphisms, there were no associations with CHD. For the rs17222842 polymorphism, there was a marginal association with the risk of CHD (OR = 1.17, 95% CI: 1.00-1.36).

CONCLUSIONS

In this meta-analysis, the HapB haplotype and rs1722842 polymorphism in ALOX5AP gene were associated with CHD, and the HapA haplotype was associated with risk of MI. The HapB haplotype may be a predictor to the risk of CHD.

Genetic contribution of the leukotriene pathway to coronary artery disease

We evaluated the genetic contribution of the leukotriene (LT) pathway to risk of coronary artery disease (CAD) in 4,512 Caucasian and African American subjects ascertained through elective cardiac evaluation. Of the three previously associated variants, the shorter “3” and “4” alleles of a promoter repeat polymorphism in ALOX5 increased risk of CAD in African Americans (OR = 1.4, 95% CI 1.0–1.9; p = 0.04), whereas a haplotype of LTA4H (HapK) was associated with CAD in Caucasians (OR = 1.2, 95% CI 1.01–1.4; p = 0.03). In Caucasians, first-stage analysis of 254 haplotype-tagging SNPs in 15 LT pathway genes with follow-up of 19 variants in stage 2 revealed an LTA4H SNP (rs2540477) that increased risk of CAD (OR = 1.2, 95% CI 1.1–1.5; p = 0.003) and a PLA2G4A SNP (rs12746200) that decreased risk of CAD (OR = 0.7, 95% CI 0.6–0.9; p = 0.0007). The PLA2G4A rs12746200 variant also decreased risk of experiencing a major adverse cardiac event (MACE = myocardial infarction, stroke, or death) over 3 years of follow-up (HR = 0.7, 95% CI 0.5–0.9; p = 0.01), consistent with its cardioprotective effect. Functional experiments demonstrated that stimulated monocytes from carriers of LTA4H variants HapK or rs2540477 had 50% (p = 0.002) and 33% (p = 0.03) higher LTB₄ production, respectively, compared to non-carriers. These ex vivo results are consistent with LTB₄ being the direct product of the reaction catalyzed by LTA4H and its role in promoting monocyte chemotaxis to sites of inflammation, including the artery wall of atherosclerotic lesions. Taken together, this study provides additional evidence that functional genetic variation of the LT pathway can mediate atherogenic processes and the risk of CAD in humans.

The 5-lipoxygenase/leukotriene pathway in preclinical models of cardiovascular disease

Leukotrienes (LTs) derived from 5-lipoxygenase (5-LO) activity are most widely known for their actions during acute inflammation and asthma. 5-LO/LT pathway involvement in cardiovascular disease (CVD) pathogenesis has come to the forefront based on provocative human genetic/population and animal studies leading to the hypothesis that this pathway promotes atherosclerosis, abdominal aortic aneurysm, and myocardial infarction/reperfusion injury via increased leucocyte chemotaxis, vascular inflammation and enhanced permeability, and subsequent tissue/matrix degeneration. A series of pre-clinical studies have tested this hypothesis by means of genetic or pharmacological inhibition of either the LT biosynthesis axis (5-LO, 5-LO-activating protein, LTA(4) hydrolase, LTC(4) synthase) or the cognate LT receptors. Here, we summarize, compare, and analyse these animal studies and relate their findings to human disease pathogenesis. We draw a complex picture of 5-LO/LT participation in cardiovascular disorders, which is further complicated by marked differences between species. Moreover, we discuss how the cytokine footprint of the respective pathological conditions determines the expression level and hence, the contribution of components of the pathway to the overall disease state. Current knowledge implies a role for 5-LO and LTs during the early/acute phase of CVD, but our understanding of a putative 5-LO/LT involvement in more advanced stages of CVD is limited, thereby preventing simple extrapolation of findings from animal studies to humans.