Genetic Association of Lipids and Lipid Drug Targets With Abdominal Aortic Aneurysm: A Meta-analysis

Proprotein convertase subtilisin/kexin type 9 as a drug target for abdominal aortic aneurysm

PURPOSE OF REVIEW

There are no current drug therapies to limit abdominal aortic aneurysm (AAA) growth. This review summarizes evidence suggesting that inhibiting proprotein convertase subtilisin/kexin type 9 (PCSK9) may be a drug target to limit AAA growth.

RECENT FINDINGS

Mendelian randomization studies suggest that raised LDL and non-HDL-cholesterol are causal in AAA formation. PCSK9 was reported to be upregulated in human AAA samples compared to aortic samples from organ donors. PCSK9 gain of function viral vectors promoted aortic expansion in C57BL/6 mice infused with angiotensin II. The effect of altering PCSK9 expression in the aortic perfusion elastase model was reported to be inconsistent. Mutations in the gene encoding PCSK9, which increase serum cholesterol, were associated with increased risk of human AAA. Patients with AAA also have a high risk of cardiovascular death, myocardial infarction and stroke. Recent research suggests that PCSK9 inhibition would substantially reduce the risk of these events.

SUMMARY

Past research suggests that drugs that inhibit PCSK9 have potential as a novel therapy for AAA to both limit aneurysm growth and reduce risk of cardiovascular events. A large multinational randomized controlled trial is needed to test if PCSK9 inhibition limits AAA growth and cardiovascular events.

Genetic evidence for lifestyle and cardiometabolic factors on the risk of aortic aneurysms: A comprehensive Mendelian randomization study

BACKGROUND AND AIMS

Aortic aneurysm (AAs) is a chronic and severe aortic disease, which is extremely life-threatening due to its delayed diagnosis and a high risk of rupture. In current studies, the association between lifestyle and metabolic factors remains controversial given the complexity of pathogenesis and progression in AAs. Consequently, more reliable and robust evidence should be provided.

METHODS

Genome-wide association studies summary statistics were obtained for 25 factors (6 lifestyle factors and 19 cardiometabolic factors) and AAs. Univariable Mendelian randomization (UVMR) and multivariable MR (MVMR) were used to estimate the causal effect of these factors on AAs. Meanwhile, mediation analysis was applied to assess the mediated effect of lifestyle on the association of cardiometabolic factors with AAs.

RESULTS

Several factors were associated with AA risk, among which triglyceride (TG) (OR = 1.32, 95 % CI = [1.18-1.47], p < 0.001) and high-density lipoprotein cholesterol (HDL-C) (OR = 0.70, 95 % CI = [0.61-0.82], p < 0.001) remain consistently associated with AA risk, with an idependent effect on AAs after adjusting for body mass index (BMI). In addition, TG mediated 15.6 % of BMI effects and 3.7 % of smoking effects on AAs, and HDL-C mediated 5.3 % of the effects of cigarette smoking on AAs.

CONCLUSIONS

TG and HDL-C may be the most reliable factors in the risk of AAs. More scientific management of lifestyle and regular monitoring for cardiometabolic traits may serve as a new and effective direction for the prevention and control of the occurrence of AAs.

The potential of a nomogram risk assessment model for the diagnosis of abdominal aortic aneurysm: a multicenter retrospective study

The incidence of abdominal aortic aneurysm (AAA) is very high, but there is no risk assessment model for early identification of AAA in clinic. The aim of this study was to develop a nomogram risk assessment model for predicting AAA. The data of 280 patients diagnosed as AAA and 385 controls in The Affiliated Suzhou Hospital of Nanjing Medical University were retrospectively reviewed. The LASSO regression method was applied to filter variables, and multivariate logistic regression was used to construct a nomogram. The discriminatory ability of the model was determined by calculating the area under the curve (AUC). The calibration capability of the model is evaluated by using bootstrap (resampling = 1000) internal validation and Hosmer-Lemeshow test. The clinical utility and clinical application value were evaluated by decision curve analysis (DCA) and clinical impact curve (CIC). In addition, a retrospective review of 133 AAA patients and 262 controls from The First Affiliated Hospital of Soochow University was performed as an external validation cohort. Eight variables are selected to construct the nomogram of AAA risk assessment model. The nomogram predicted AAA with AUC values of 0.928 (95%CI, 0.907-0.950) in the training cohort, and 0.902 (95%CI, 0.865-0.940) in the external validation cohort, the risk prediction model has excellent discriminative ability. The calibration curve and Hosmer-Lemeshow test proved that the nomogram predicted outcomes were close to the ideal curve, the predicted outcomes were consistent with the real outcomes, the DCA curve and CIC curve showed that patients could benefit. This finding was also confirmed in the external validation cohort. In this study, a nomogram was constructed that incorporated eight demographic and clinical characteristics of AAA patients, which can be used as a practical approach for the personalized early screening and auxiliary diagnosis of the potential risk factors.

Genetic Association of Lipids and Lipid-Lowering Drug Target Genes With Attention Deficit Hyperactivity Disorder

BACKGROUND

Lipid metabolism plays an essential role in nervous system development. Cholesterol deficiency leads to a variety of neurodevelopmental disorders, such as autism spectrum disorder and fragile X syndrome. There have been a lot of efforts to search for biological markers associated with and causal to ADHD, among which lipid is one possible etiological factor that is quite widely studied. We aimed to evaluate the causal relationship between lipids traits, lipid-lowering drugs, and attention deficit hyperactivity disorder (ADHD) outcomes using Mendelian randomization (MR) studies.

METHODS

We used summary data from genome-wide association studies to explore the causal relationships between circulating lipid-related traits and ADHD. Then, quantitative trait loci for the expression of lipid-lowering drug target genes and genetic variants associated with lipid traits were extracted. Summary-data-based MR and inverse-variance-weighted MR (IVW-MR) were used to investigate the correlation between the expression of these drug-target genes and ADHD.

RESULTS

After rigorous screening, 939 instrumental variables were finally included for univariable mendelian randomization analysis. However, there is no correlation between lipid profile and ADHD risk. Drug target analysis by IVW-MR method observed that APOB-mediated low-density lipoprotein cholesterol was associated with lower ADHD risk (odds ratio [OR] = 0.90, 95% confidence interval [CI] [0.84, 0.97]; p = .007), whereas LPL-mediated triglycerides levels were associated with a higher risk of ADHD (OR = 1.13, 95% CI [1.06, 1.21]; p < .001).

CONCLUSION

Our results suggest that APOB gene and LPL gene may be candidate drug target genes for the treatment of ADHD.

Medical treatments for abdominal aortic aneurysm: an overview of clinical trials

INTRODUCTION

Abdominal aortic aneurysm is a progressive, segmental, abdominal aortic dilation associated with a high mortality rate. Abdominal aortic aneurysms with diameters larger than 55 mm are associated with a high risk of rupture, and the most effective treatment options are surgical repair. Close observation and lifestyle adjustments are recommended for smaller abdominal aortic aneurysms with lower rupture risk. The development of medical therapies that limit or prevent the progression, expansion, and eventual rupture of abdominal aortic aneurysms remains an unmet clinical need.

AREAS COVERED

This review provides an overview of completed and ongoing clinical trials examining the efficacies of various drug classes, including antibiotics, antihypertensive drugs, hypolipidemic drugs, hypoglycemic drugs, and other potential therapies for abdominal aortic aneurysms. A search of PubMed, Web of Science, Clinical Trials, and another six clinical trial registries was conducted in January 2024.

EXPERT OPINION

None of the drugs have enough evidence to indicate that they can effectively inhibit the dilation of abdominal aortic aneurysm. More clinical trial data is required to support the efficacy of propranolol. Future research should also explore different drug delivery mechanisms, such as nanoparticles, to elevate drug concentration at the aneurysm wall.

Genetic association of lipid traits and lipid-related drug targets with normal tension glaucoma: a Mendelian randomization study for predictive preventive and personalized medicine

Background

Glaucoma is the leading cause of irreversible blindness worldwide. Normal tension glaucoma (NTG) is a distinct subtype characterized by intraocular pressures (IOP) within the normal range (< 21 mm Hg). Due to its insidious onset and optic nerve damage, patients often present with advanced conditions upon diagnosis. NTG poses an additional challenge as it is difficult to identify with normal IOP, complicating its prediction, prevention, and treatment. Observational studies suggest a potential association between NTG and abnormal lipid metabolism, yet conclusive evidence establishing a direct causal relationship is lacking. This study aims to explore the causal link between serum lipids and NTG, while identifying lipid-related therapeutic targets. From the perspective of predictive, preventive, and personalized medicine (PPPM), clarifying the role of dyslipidemia in the development of NTG could provide a new strategy for primary prediction, targeted prevention, and personalized treatment of the disease.

Working hypothesis and methods

In our study, we hypothesized that individuals with dyslipidemia may be more susceptible to NTG due to a dysregulation of microvasculature in optic nerve head. To verify the working hypothesis, univariable Mendelian randomization (UVMR) and multivariable Mendelian randomization (MVMR) were utilized to estimate the causal effects of lipid traits on NTG. Drug target MR was used to explore possible target genes for NTG treatment. Genetic variants associated with lipid traits and variants of genes encoding seven lipid-related drug targets were extracted from the Global Lipids Genetics Consortium genome-wide association study (GWAS). GWAS data for NTG, primary open angle glaucoma (POAG), and suspected glaucoma (GLAUSUSP) were obtained from FinnGen Consortium. For apolipoproteins, we used summary statistics from a GWAS study by Kettunen et al. in 2016. For metabolic syndrome, summary statistics were extracted from UK Biobank participants. In the end, these findings could help identify individuals at risk of NTG by screening for lipid dyslipidemia, potentially leading to new targeted prevention and personalized treatment approaches.

Results

Genetically assessed high-density cholesterol (HDL) was negatively associated with NTG risk (inverse-variance weighted [IVW] model: OR per SD change of HDL level = 0.64; 95% CI, 0.49-0.85; P = 1.84 × 10-3), and the causal effect was independent of apolipoproteins and metabolic syndrome (IVW model: OR = 0.29; 95% CI, 0.14-0.60; P = 0.001 adjusted by ApoB and ApoA1; OR = 0.70; 95% CI, 0.52-0.95; P = 0.023 adjusted by BMI, HTN, and T2DM). Triglyceride (TG) was positively associated with NTG risk (IVW model: OR = 1.62; 95% CI, 1.15-2.29; P = 6.31 × 10-3), and the causal effect was independent of metabolic syndrome (IVW model: OR = 1.66; 95% CI, 1.18-2.34; P = 0.003 adjusted by BMI, HTN, and T2DM), but not apolipoproteins (IVW model: OR = 1.71; 95% CI, 0.99-2.95; P = 0.050 adjusted by ApoB and ApoA1). Genetic mimicry of apolipoprotein B (APOB) enhancement was associated with lower NTG risks (IVW model: OR = 0.09; 95% CI, 0.03-0.26; P = 9.32 × 10-6).

Conclusions

Our findings supported dyslipidemia as a predictive causal factor for NTG, independent of other factors such as metabolic comorbidities. Among seven lipid-related drug targets, APOB is a potential candidate drug target for preventing NTG. Personalized health profiles can be developed by integrating lipid metabolism with life styles, visual quality of life such as reading, driving, and walking. This comprehensive approach will aid in shifting from reactive medical services to PPPM in the management of NTG.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-024-00373-5.

Exploration of small molecule compounds targeting abdominal aortic aneurysm based on CMap database and molecular dynamics simulation

OBJECTIVE

The mitigation of abdominal aortic aneurysm (AAA) growth through pharmaceutical intervention offers the potential to avert the perils associated with AAA rupture and the subsequent need for surgical intervention. Nevertheless, the existing effective drugs for AAA treatment are limited, necessitating a pressing exploration for novel therapeutic medications.

METHODS

AAA-related transcriptome data were downloaded from GEO, and differentially expressed genes (DEGs) in AAA tissue were screened for GO and KEGG enrichment analyses. Small molecule compounds and their target proteins with negative connectivity to the AAA expression profile were predicted in the Connectivity Map (CMap) database. Molecular docking and molecular dynamics simulation were performed to predict the binding of the target protein to the small molecule compound, and the MM/GBSA method was used to calculate the binding free energy. Cluster analysis was performed using the cluster tool in the GROMACS package. An AAA cell-free model was built, and CETSA experiments were used to demonstrate the binding ability of small molecules to the target protein in cells.

RESULTS

A total of 2244 DEGs in AAA were obtained through differential analysis, and the DEGs were mainly enriched in the tubulin binding biological function and cell cycle pathway. The CMap results showed that Apicidin had a potential therapeutic effect on AAA with a connectivity score of -97.74, and HDAC4 was the target protein of Apicidin. Based on literature, HDAC4-Apicidin was selected as the subsequent research object. The lowest affinity of Apicidin-HDAC4 molecular docking was -8.218 kcal/mol. Molecular dynamics simulation results indicated that Apicidin-HDAC4 could form a stable complex. MM/GBSA analysis showed a total binding free energy of -55.40 ± 0.79 kcal/mol, and cluster analysis showed that there were two main conformational clusters during the binding process, accounting for 22.4% and 57.8%, respectively. Apicidin could form hydrogen bonds with surrounding residues for stable binding. CETSA experiment proved the stable binding ability of Apicidin and HDAC4.

CONCLUSION

Apicidin inhibited HDAC4 in AAA and exhibited favorable protein-ligand interactions and stability, making it a potential candidate drug for treating AAA.

Hypertriglyceridemia as a Key Contributor to Abdominal Aortic Aneurysm Development and Rupture: Insights from Genetic and Experimental Models

Abdominal aortic aneurysm (AAA) is a life-threatening vascular disease without effective medications. This study integrated genetic, proteomic, and metabolomic data to identify causation between increased triglyceride (TG)-rich lipoproteins and AAA risk. Three hypertriglyceridemia mouse models were employed to test the hypothesis that increased plasma TG concentrations accelerate AAA development and rupture. In the angiotensin II-infusion AAA model, most Lpl -deficient mice with severely high plasma TG concentrations died of aortic rupture. Consistently, Apoa5 -deficient mice with moderately increased TG concentrations had accelerated AAA development, while human APOC3 transgenic mice with dramatically increased TG concentrations exhibited aortic dissection and rupture. Increased TG concentrations and palmitate inhibited lysyl oxidase maturation. Administration of antisense oligonucleotide targeting Angptl3 profoundly inhibited AAA progression in human APOC3 transgenic mice and Apoe -deficient mice. These results indicate that hypertriglyceridemia is a key contributor to AAA pathogenesis, highlighting the importance of triglyceride-rich lipoprotein management in treating AAA.

Genetic association of lipid and lipid-lowering drug target genes with atopic dermatitis: a drug target Mendelian randomization study

Observational studies suggest dyslipidemia as an atopic dermatitis (AD) risk factor and posit that lipid-lowering drugs may influence AD risk, but the causal link remains elusive. Mendelian randomization was applied to elucidate the causal role of serum lipids in AD and assess the therapeutic potential of lipid-lowering drug targets. Genetic variants related to serum lipid traits and lipid-lowering drug targets were sourced from the Global Lipid Genetics Consortium GWAS data. Comprehensive AD data were collated from the UK Biobank, FinnGen, and Biobank Japan. Colocalization, Summary-data-based Mendelian Randomization (SMR), and mediation analyses were utilized to validate the results and pinpoint potential mediators. Among assessed targets, only Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) was significantly linked to a reduced AD risk, corroborated across three separate AD cohorts. No association between serum lipid concentrations or other lipid-lowering drug targets and diminished AD risk was observed. Mediation analysis revealed that beta nerve growth factor (b-NGF) might mediate approximately 12.8% of PCSK9's influence on AD susceptibility. Our findings refute dyslipidemia's role in AD pathogenesis. Among explored lipid-lowering drug targets, PCSK9 stands out as a promising therapeutic agent for AD.

Causal Relationships between Lipid-Lowering Drug Target and Aortic Disease and Calcific Aortic Valve Stenosis: A Two-Sample Mendelian Randomization

Background

Proprotein convertase subtilisin/kexin type 9 (PCSK9), 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR), cholesteryl ester transfer protein (CETP) and apolipoprotein C3 (APOC3) are pivotal regulators of lipid metabolism, with licensed drugs targeting these genes. The use of lipid-lowering therapy via the inhibition of these genes has demonstrated a reduction in the risk of cardiovascular disease. However, concerns persist regarding their potential long-term impact on aortic diseases and calcific aortic valve disease (CAVS). This study aims to investigate causal relationships between genetic variants resembling these genes and aortic disease, as well as calcific aortic valve disease using Mendelian randomization (MR).

Methods

We conducted drug-target Mendelian randomization employing summary-level statistics of low-density lipoprotein cholesterol (LDL-C) to proxy the loss-of-function of PCSK9, HMGCR, CETP and APOC3. Subsequently, we investigated the association between drug-target genetic variants and calcific aortic valve stenosis and aortic diseases, including thoracic aortic aneurysm (TAA), abdominal aortic aneurysm (AAA), and aortic dissection (AD).

Results

The genetically constructed variants mimicking lower LDL-C levels were associated with a decreased risk of coronary artery disease, validating their reliability. Notably, HMGCR inhibition exhibited a robust protective effect against TAA (odds ratio (OR): 0.556, 95% CI: 0.372-0.831, p = 0.004), AAA (OR: 0.202, 95% CI: 0.107-0.315, p = 4.84 × 10-15), and AD (OR: 0.217, 95% CI: 0.098-0.480, p = 0.0002). Similarly, PCSK9, CETP and APOC3 inhibition proxies reduced the risk of AAA (OR: 0.595, 95% CI: 0.485-0.730, p = 6.75 × 10-7, OR: 0.127, 95% CI: 0.066-0.243, p = 4.42 × 10-10, and OR: 0.387, 95% CI: 0.182-0.824, p = 0.014, respectively) while showing a neutral impact on TAA and AD. Inhibition of HMGCR, PCSK9, and APOC3 showed promising potential in preventing CAVS with odds ratios of 0.554 (OR: 0.554, 95% CI: 0.433-0.707, p = 2.27 × 10-6), 0.717 (95% CI: 0.635-0.810, p = 9.28 × 10-8), and 0.540 (95% CI: 0.351-0.829, p = 0.005), respectively. However, CETP inhibition did not demonstrate any significant benefits in preventing CAVS (95% CI: 0.704-1.544, p = 0.836). The consistency of these findings across various Mendelian randomization methods, accounting for different assumptions concerning genetic pleiotropy, enhances the causal inference.

Conclusions

Our MR analysis reveals that genetic variants resembling statin administration are associated with a reduced risk of AAA, TAA, AD and CAVS. HMGCR, PCSK9 and APOC3 inhibitors but not CETP inhibitors have positive benefits of reduced CAVS. Notably, PCSK9, CETP and APOC3 inhibitors exhibit a protective impact, primarily against AAA, with no discernible benefits extending to TAA or AD.

Genetic association of lipid-lowering drugs with aortic aneurysms: a Mendelian randomization study

AIMS

The lack of effective pharmacotherapies for aortic aneurysms (AA) is a persistent clinical challenge. Lipid metabolism plays an essential role in AA. However, the impact of lipid-lowering drugs on AA remains controversial. The study aimed to investigate the genetic association between lipid-lowering drugs and AA.

METHODS AND RESULTS

Our research used publicly available data on genome-wide association studies (GWASs) and expression quantitative trait loci (eQTL) studies. Genetic instruments, specifically eQTLs related to drug-target genes and SNPs (single nucleotide polymorphisms) located near or within the drug-target loci associated with low-density lipoprotein cholesterol (LDL-C), have been served as proxies for lipid-lowering medications. Drug-Target Mendelian Randomization (MR) study is used to determine the causal association between lipid-lowering drugs and different types of AA. The MR analysis revealed that higher expression of HMGCR (3-hydroxy-3-methylglutaryl coenzyme A reductase) was associated with increased risk of AA (OR = 1.58, 95% CI = 1.20-2.09, P = 1.20 × 10-03) and larger lumen size (aortic maximum area: OR = 1.28, 95% CI = 1.13-1.46, P = 1.48 × 10-04; aortic minimum area: OR = 1.26, 95% CI = 1.21-1.42, P = 1.78 × 10-04). PCSK9 (proprotein convertase subtilisin/kexin type 9) and CETP (cholesteryl ester transfer protein) show a suggestive relationship with AA (PCSK9: OR = 1.34, 95% CI = 1.10-1.63, P = 3.07 × 10-03; CETP: OR = 1.38, 95% CI = 1.06-1.80, P = 1.47 × 10-02). No evidence to support genetically mediated NPC1L1 (Niemann-Pick C1-Like 1) and LDLR (low-density lipoprotein cholesterol receptor) are associated with AA.

CONCLUSION

This study provides causal evidence for the genetic association between lipid-lowering drugs and AA. Higher gene expression of HMGCR, PCSK9, and CETP increases AA risk. Furthermore, HMGCR inhibitors may link with smaller aortic lumen size.

Abdominal aortic aneurysm and cardiometabolic traits share strong genetic susceptibility to lipid metabolism and inflammation

Abdominal aortic aneurysm has a high heritability and often co-occurs with other cardiometabolic disorders, suggesting shared genetic susceptibility. We investigate this commonality leveraging recent GWAS studies of abdominal aortic aneurysm and 32 cardiometabolic traits. We find significant genetic correlations between abdominal aortic aneurysm and 21 of the cardiometabolic traits investigated, including causal relationships with coronary artery disease, hypertension, lipid traits, and blood pressure. For each trait pair, we identify shared causal variants, genes, and pathways, revealing that cholesterol metabolism and inflammation are shared most prominently. Additionally, we show the tissue and cell type specificity in the shared signals, with strong enrichment across traits in the liver, arteries, adipose tissues, macrophages, adipocytes, and fibroblasts. Finally, we leverage drug-gene databases to identify several lipid-lowering drugs and antioxidants with high potential to treat abdominal aortic aneurysm with comorbidities. Our study provides insight into the shared genetic mechanism between abdominal aortic aneurysm and cardiometabolic traits, and identifies potential targets for pharmacological intervention.

Causal relationship between immune cells and aortic aneurysms: a Mendelian randomization study

OBJECTIVES

The causal association between immune cell traits and aortic aneurysm remains unknown.

METHODS

We performed a bidirectional two-sample Mendelian randomization analysis to explore the causality between 731 immune cell characteristics and the risk of abdominal aortic aneurysm and thoracic aortic aneurysms through publicly available genetic data, respectively. To examine heterogeneity and horizontal pleiotropy, Cochran's Q test and MR-Egger intercept were utilized. Additionally, multivariable Mendelian randomization analysis and meta-analysis were performed in further analysis.

RESULTS

We found that 20 immune phenotypes had a suggestive causality on abdominal aortic aneurysm, and 15 immune phenotypes had a suggestive causal effect on thoracic aortic aneurysm. After further false discovery rate adjustment (q value <0.1), CD20 on IgD+ CD38- B cell (q = 0.053) and CD127 on CD28+ CD4+ T cell (q = 0.096) were associated with an increased risk of abdominal aortic aneurysm, respectively, indicating a significant causality between them. After adjusting for smoking, there is still statistical significance between CD127 on CD28+ CD4+ T cell and abdominal aortic aneurysm. However, after adjusting for lipids, no statistical significance can be observed between CD127 on CD28+ CD4+ T cells and abdominal aortic aneurysm. Furthermore, there is still statistical significance between CD20 on IgD+ CD38- B cells and abdominal aortic aneurysm after adjusting for lipids and smoking, which was further identified by meta-analysis.

CONCLUSIONS

We found a causal association between immune cell traits and aortic aneurysm by genetic methods, thus providing new avenues for future mechanism studies.

Exploring the Causal Effects of Mineral Metabolism Disorders on Telomere and Mitochondrial DNA: A Bidirectional Two-Sample Mendelian Randomization Analysis

The aim of this study was to assess the causal relationships between mineral metabolism disorders, representative of trace elements, and key aging biomarkers: telomere length (TL) and mitochondrial DNA copy number (mtDNA-CN). Utilizing bidirectional Mendelian randomization (MR) analysis in combination with the two-stage least squares (2SLS) method, we explored the causal relationships between mineral metabolism disorders and these aging indicators. Sensitivity analysis can be used to determine the reliability and robustness of the research results. The results confirmed that a positive causal relationship was observed between mineral metabolism disorders and TL (p < 0.05), while the causal relationship with mtDNA-CN was not significant (p > 0.05). Focusing on subgroup analyses of specific minerals, our findings indicated a distinct positive causal relationship between iron metabolism disorders and both TL and mtDNA-CN (p < 0.05). In contrast, disorders in magnesium and phosphorus metabolism did not exhibit significant causal effects on either aging biomarker (p > 0.05). Moreover, reverse MR analysis did not reveal any significant causal effects of TL and mtDNA-CN on mineral metabolism disorders (p > 0.05). The combination of 2SLS with MR analysis further reinforced the positive causal relationship between iron levels and both TL and mtDNA-CN (p < 0.05). Notably, the sensitivity analysis did not indicate significant pleiotropy or heterogeneity within these causal relationships (p > 0.05). These findings highlight the pivotal role of iron metabolism in cellular aging, particularly in regulating TL and sustaining mtDNA-CN, offering new insights into how mineral metabolism disorders influence aging biomarkers. Our research underscores the importance of trace element balance, especially regarding iron intake, in combating the aging process. This provides a potential strategy for slowing aging through the adjustment of trace element intake, laying the groundwork for future research into the relationship between trace elements and healthy aging.

Deciphering the role of CX3CL1-CX3CR1 in aortic aneurysm pathogenesis: insights from Mendelian randomization and transcriptomic analyses

Background

The crucial role of inflammation in aortic aneurysm (AA) is gaining prominence, while there is still a lack of key cytokines or targets for effective clinical translation.

Methods

Mendelian randomization (MR) analysis was performed to identify the causal relationship between 91 circulating inflammatory proteins and AA and between 731 immune traits and AA. Bulk RNA sequencing data was utilized to demonstrate the expression profile of the paired ligand-receptor. Gene enrichment analysis, Immune infiltration, and correlation analysis were employed to deduce the potential role of CX3CR1. We used single-cell RNA sequencing data to pinpoint the localization of CX3CL1 and CX3CR1, which was further validated by multiplex immunofluorescence staining. Cellchat analysis was utilized to infer the CX3C signaling pathway. Trajectory analysis and the Cytosig database were exploited to determine the downstream effect of CX3CL1-CX3CR1.

Results

We identified 4 candidates (FGF5, CX3CL1, IL20RA, and SCF) in multiple two-sample MR analyses. Subsequent analysis of the expression profile of the paired receptor revealed the significant upregulation of CX3CR1 in AA and its positive correlation with pro-inflammatory macrophages. Two sample MR between immune cell traits and AA demonstrated the potential causality between intermediate monocytes and AA. We finally deciphered in single-cell sequencing data that CX3CL1 sent by endothelial cells (ECs) acted on CX3CR1 of intermediated monocytes, leading to its recruitment and pro-inflammatory responses.

Conclusion

Our study presented a genetic insight into the pathogenetic role of CX3CL1-CX3CR1 in AA, and further deciphered the CX3C signaling pathway between ECs and intermediate monocytes.

Transcriptomic analysis identifies the shared diagnostic biomarkers and immune relationship between Atherosclerosis and abdominal aortic aneurysm based on fatty acid metabolism gene set

Background

Epidemiological research has demonstrated that there is a connection between lipid metabolism disorder and an increased risk of developing arteriosclerosis (AS) and abdominal aortic aneurysm (AAA). However, the precise relationship between lipid metabolism, AS, and AAA is still not fully understood. The objective of this study was to examine the pathways and potential fatty acid metabolism-related genes (FRGs) that are shared between AS and AAA.

Methods

AS- and AAA-associated datasets were retrieved from the Gene Expression Omnibus (GEO) database, and the limma package was utilized to identify differentially expressed FRGs (DFRGs) common to both AS and AAA patients. Functional enrichment analysis was conducted on the (DFRGs), and a protein-protein interaction (PPI) network was established. The selection of signature genes was performed through the utilization of least absolute shrinkage and selection operator (LASSO) regression and random forest (RF). Subsequently, a nomogram was developed using the results of the screening process, and the crucial genes were validated in two separate external datasets (GSE28829 and GSE17901) as well as clinical samples. In the end, single-sample gene set enrichment analysis (ssGSEA) was utilized to assess the immune cell patterns in both AS and AAA. Additionally, the correlation between key crosstalk genes and immune cell was evaluated.

Results

In comparison to control group, both AS and AAA patients exhibited a decrease in fatty acid metabolism score. We found 40 DFRGs overlapping in AS and AAA, with lipid and amino acid metabolism critical in their pathogenesis. PCBD1, ACADL, MGLL, BCKDHB, and IDH3G were identified as signature genes connecting AS and AAA. Their expression levels were confirmed in validation datasets and clinical samples. The analysis of immune infiltration showed that neutrophils, NK CD56dim cells, and Tem cells are important in AS and AAA development. Correlation analysis suggested that these signature genes may be involved in immune cell infiltration.

Conclusion

The fatty acid metabolism pathway appears to be linked to the development of both AS and AAA. Furthermore, PCBD1, ACADL, MGLL, BCKDHB, and IDH3G have the potential to serve as diagnostic markers for patients with AS complicated by AAA.

Elevated blood remnant cholesterol and triglycerides are causally related to the risks of cardiometabolic multimorbidity

The connection between triglyceride-rich lipoproteins and cardiometabolic multimorbidity, characterized by the concurrence of at least two of type 2 diabetes, ischemic heart disease, and stroke, has not been definitively established. We aim to examine the prospective associations between serum remnant cholesterol, triglycerides, and the risks of progression from first cardiometabolic disease to multimorbidity via multistate modeling in the UK Biobank. We also evaluate the causality of these associations via Mendelian randomization using 13 biologically relevant SNPs as the genetic instruments. Here we show that elevated remnant cholesterol and triglycerides are significantly associated with gradually higher risks of cardiometabolic multimorbidity, particularly the progression of ischemic heart disease to the multimorbidity of ischemic heart disease and type 2 diabetes. These results advocate for effective management of remnant cholesterol and triglycerides as a potential strategy in mitigating the risks of cardiometabolic multimorbidity.

Targeted proteomics and metabolomics for biomarker discovery in abdominal aortic aneurysm and post-EVAR sac volume

BACKGROUND AND AIMS

Abdominal aortic aneurysm (AAA) patients undergo uniform surveillance programs both leading up to, and following surgery. Circulating biomarkers could play a pivotal role in individualizing surveillance. We applied a multi-omics approach to identify relevant biomarkers and gain pathophysiological insights.

MATERIALS AND METHODS

In this cross-sectional study, 108 AAA patients and 200 post-endovascular aneurysm repair (post-EVAR) patients were separately investigated. We performed partial least squares regression and ingenuity pathway analysis on circulating concentrations of 96 proteins (92 Olink Cardiovascular-III panel, 4 ELISA-assays) and 199 metabolites (measured by LC-TQMS), and their associations with CT-based AAA/sac volume.

RESULTS

The median (25th-75th percentile) maximal diameter was 50.0 mm (46.0, 53.0) in the AAA group, and 55.4 mm (45.0, 64.2) in the post-EVAR group. Correcting for clinical characteristics in AAA patients, the aneurysm volume Z-score differed 0.068 (95 %CI: (0.042, 0.093)), 0.066 (0.047, 0.085) and -0.051 (-0.064, -0.038) per Z-score valine, leucine and uPA, respectively. After correcting for clinical characteristics and orthogonalization in the post-EVAR group, the sac volume Z-score differed 0.049 (0.034, 0.063) per Z-score TIMP-4, -0.050 (-0.064, -0.037) per Z-score LDL-receptor, -0.051 (-0.062, -0.040) per Z-score 1-OG/2-OG and -0.056 (-0.066, -0.045) per Z-score 1-LG/2-LG.

CONCLUSIONS

The branched-chain amino acids and uPA were related to AAA volume. For post-EVAR patients, LDL-receptor, monoacylglycerols and TIMP-4 are potential biomarkers for sac volume. Additionally, distinct markers for sac change were identified.

The landscape of the methodology in drug repurposing using human genomic data: a systematic review

The process of drug development is expensive and time-consuming. In contrast, drug repurposing can be introduced to clinical practice more quickly and at a reduced cost. Over the last decade, there has been a significant expansion of large biobanks that link genomic data to electronic health record data, public availability of various databases containing biological and clinical information and rapid development of novel methodologies and algorithms in integrating different sources of data. This review aims to provide a thorough summary of different strategies that utilize genomic data to seek drug-repositioning opportunities. We searched MEDLINE and EMBASE databases to identify eligible studies up until 1 May 2023, with a total of 102 studies finally included after two-step parallel screening. We summarized commonly used strategies for drug repurposing, including Mendelian randomization, multi-omic-based and network-based studies and illustrated each strategy with examples, as well as the data sources implemented. By leveraging existing knowledge and infrastructure to expedite the drug discovery process and reduce costs, drug repurposing potentially identifies new therapeutic uses for approved drugs in a more efficient and targeted manner. However, technical challenges when integrating different types of data and biased or incomplete understanding of drug interactions are important hindrances that cannot be disregarded in the pursuit of identifying novel therapeutic applications. This review offers an overview of drug repurposing methodologies, providing valuable insights and guiding future directions for advancing drug repurposing studies.

Mendelian randomization for cardiovascular diseases: principles and applications

Large-scale genome-wide association studies conducted over the last decade have uncovered numerous genetic variants associated with cardiometabolic traits and risk factors. These discoveries have enabled the Mendelian randomization (MR) design, which uses genetic variation as a natural experiment to improve causal inferences from observational data. By analogy with the random assignment of treatment in randomized controlled trials, the random segregation of genetic alleles when DNA is transmitted from parents to offspring at gamete formation is expected to reduce confounding in genetic associations. Mendelian randomization analyses make a set of assumptions that must hold for valid results. Provided that the assumptions are well justified for the genetic variants that are employed as instrumental variables, MR studies can inform on whether a putative risk factor likely has a causal effect on the disease or not. Mendelian randomization has been increasingly applied over recent years to predict the efficacy and safety of existing and novel drugs targeting cardiovascular risk factors and to explore the repurposing potential of available drugs. This review article describes the principles of the MR design and some applications in cardiovascular epidemiology.

Genetic association between coffee/caffeine consumption and the risk of obstructive sleep apnea in the European population: a two-sample Mendelian randomization study

BACKGROUND

The association between coffee/caffeine consumption and obstructive sleep apnea (OSA) risk remains unclear.

PURPOSE

To determine the relationship between coffee/caffeine consumption and the risk of OSA, using the Mendelian randomization (MR) method in the European population.

METHODS

Two sets of coffee consumption-associated genetic variants were, respectively, extracted from the recent genome-wide meta-analysis (GWMA) and genome-wide association study (GWAS) of coffee consumption. Taking other caffeine sources into account, genetic variants associated with caffeine consumption from tea and plasma caffeine (reflecting total caffeine intake) were also obtained. The inverse variance weighted (IVW) technique was utilized as the primary analysis, supplemented by the MR-Egger, weighted-median, and MR-Pleiotropy RESidual Sum and Outlier (PRESSO) techniques. Leave-one-out (LOO) analysis was performed to assess whether the overall casual estimates were driven by a single SNP. Additional sensitivity analyses were performed using similar methods, while the genetic variants associated with confounders, e.g., body mass index and hypertension, were excluded.

RESULTS

The IVW method demonstrated that coffee consumption GWMA (OR: 1.065, 95% CI 0.927-1.224, p = 0.376), coffee consumption GWAS (OR: 1.665, 95% CI 0.932-2.977, p = 0.086), caffeine from tea (OR: 1.198, 95% CI 0.936-1.534, p = 0.151), and blood caffeine levels (OR: 1.054, 95% CI 0.902-1.231, p = 0.508) were unlikely to be associated with the risk of OSA. The other three methods presented similar results, where no significant associations were found. No single genetic variant was driving the overall estimates by the LOO analysis. These findings were also supported by the sensitivity analyses with no confounding genetic variants.

CONCLUSION

Our study found no association between coffee/caffeine consumption and the risk of OSA.

Genome-wide association meta-analysis identifies risk loci for abdominal aortic aneurysm and highlights PCSK9 as a therapeutic target

Abdominal aortic aneurysm (AAA) is a common disease with substantial heritability. In this study, we performed a genome-wide association meta-analysis from 14 discovery cohorts and uncovered 141 independent associations, including 97 previously unreported loci. A polygenic risk score derived from meta-analysis explained AAA risk beyond clinical risk factors. Genes at AAA risk loci indicate involvement of lipid metabolism, vascular development and remodeling, extracellular matrix dysregulation and inflammation as key mechanisms in AAA pathogenesis. These genes also indicate overlap between the development of AAA and other monogenic aortopathies, particularly via transforming growth factor β signaling. Motivated by the strong evidence for the role of lipid metabolism in AAA, we used Mendelian randomization to establish the central role of nonhigh-density lipoprotein cholesterol in AAA and identified the opportunity for repurposing of proprotein convertase, subtilisin/kexin-type 9 (PCSK9) inhibitors. This was supported by a study demonstrating that PCSK9 loss of function prevented the development of AAA in a preclinical mouse model.

Prevalence of risk factors associated with rupture of abdominal aortic aneurysm (AAA): a single center retrospective study

BACKGROUND

Abdominal aortic aneurysm (AAA) is a severe cardiovascular disease. The mortality rate for an AAA rupture is very high. Understanding the risk factors for AAA rupture would help AAA management, but little is known about these risk factors in the Chinese population.

METHODS

This retrospective study included patients that were diagnosed with AAA during the last 5 years in a large national hospital in southern China. AAA patients were divided into a rupture and non-rupture group. Clinical data were extracted from the hospital medical record system. Clinical features were compared between the rupture and non-rupture groups. The associations between potential risk factors and rupture risk were evaluated using a multivariate logistic regression analysis.

RESULTS

A total of 337 AAA patients were included for analysis in the present study. AAA diameter was significantly larger, and high-sensitivity C-reactive protein (hs-CRP) and serum creatinine levels were both significantly higher in AAA rupture patients. High-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and total cholesterol (TC) levels were significantly lower in AAA rupture patients. After adjustment, the multivariate logistic analysis found that AAA diameter and hs-CRP were independently positively associated with AAA rupture, and HDL-C level was adversely associated with AAA rupture.

CONCLUSIONS

Our data suggests that larger AAA diameter and higher hs-CRP level are associated with a higher risk of AAA rupture, and higher HDL-C level is associated with a lower risk of AAA rupture. The results of this study may be helpful for the management of AAA patients in southern China.

Genome-wide association study of thoracic aortic aneurysm and dissection in the Million Veteran Program

The current understanding of the genetic determinants of thoracic aortic aneurysms and dissections (TAAD) has largely been informed through studies of rare, Mendelian forms of disease. Here, we conducted a genome-wide association study (GWAS) of TAAD, testing ~25 million DNA sequence variants in 8,626 participants with and 453,043 participants without TAAD in the Million Veteran Program, with replication in an independent sample of 4,459 individuals with and 512,463 without TAAD from six cohorts. We identified 21 TAAD risk loci, 17 of which have not been previously reported. We leverage multiple downstream analytic methods to identify causal TAAD risk genes and cell types and provide human genetic evidence that TAAD is a non-atherosclerotic aortic disorder distinct from other forms of vascular disease. Our results demonstrate that the genetic architecture of TAAD mirrors that of other complex traits and that it is not solely inherited through protein-altering variants of large effect size.

Plasma Lipidomics Analysis Reveals the Potential Role of Lysophosphatidylcholines in Abdominal Aortic Aneurysm Progression and Formation

Abdominal aortic aneurysm (AAA) is hallmarked by irreversible dilation of the infrarenal aorta. Lipid deposition in the aortic wall and the potential importance of a lipid disorder in AAA etiology highlight the need to explore lipid variation during AAA development. This study aimed to systematically characterize the lipidomics associated with AAA size and progression. Plasma lipids from 106 subjects (36 non-AAA controls and 70 AAA patients) were comprehensively analyzed using untargeted lipidomics. An AAA animal model was established by embedding angiotensin-II pump in ApoE^-/- mice for four weeks and blood was collected at 0, 2 and 4 weeks for lipidomic analysis. Using a false-discovery rate (FDR) < 0.05, a group of lysophosphatidylcholines (lysoPCs) were specifically decreased in AAA patients and mice. LysoPCs were principally lower in the AAA patients with larger diameter (diameter > 50 mm) than those with a smaller size (30 mm < diameter < 50 mm), and levels of lysoPCs were also found to be decreased with modelling time and aneurysm formation in AAA mice. Correlation matrices between lipids and clinical characteristics identified that the positive correlation between lysoPCs and HDL-c was reduced and negative correlations between lysoPCs and CAD rate, lysoPCs and hsCRP were converted to positive correlations in AAA compared to control. Weakened positive correlations between plasma lysoPCs and circulating HDL-c in AAA suggested that HDL-lysoPCs may elicit instinctive physiological effects in AAA. This study provides evidence that reduced lysoPCs essentially underlie the pathogenesis of AAA and that lysoPCs are promising biomarkers for AAA development.

Association of MLL3 and TGF-β signaling gene polymorphisms with the susceptibility and prognostic outcomes of Stanford type B aortic dissection : MLL3 with TGF-β signal pathway association with Stanford type B AD

OBJECTIVE

This study aims to investigate the association of lysine methyltransferase 2 C (MLL3) and transforming growth factor β (TGF-β) signaling-related gene polymorphisms with the susceptibility of Stanford type B aortic dissection (AD) and its clinical prognostic outcomes. The methods involved investigating the MLL3 (rs10244604, rs6963460, rs1137721), TGFβ1 (rs1800469), TGFβ2 (rs900), TGFR1 (rs1626340) and TGFR2 (rs4522809) gene polymorphisms. Logistic regression was performed to investigate the association between 7 single nucleotide gene polymorphisms (SNPs) and Stanford type B aortic dissection. The GMDR software was used to analyze gene-gene and gene-environment interactions. The odds ratio (OR) with a 95% confidence interval (CI) was employed to evaluate the association of genes and Stanford type B AD risk.

RESULTS

Genotypes and allele distributions in the case and control groups showed significant differences (P < 0.05). Logistic regression has shown that the Stanford Type B AD risk was highest in individuals with the rs1137721 CT genotype (OR = 4.33, 95% CI = 1.51-12.40). Additionally, WBC, drinking, hypertension, triglycerides (TG), and low-density lipoprotein (LDL-C) were independent risk factors for Stanford Type B AD. Logistic regression showed that the Stanford Type B AD risk was highest in individuals with the MLL3 (rs1137721)-TT + CT and TGFβ1 (rs4522809)-AA genotype (OR = 6.72, 95% CI = 1.56-29.84), and lowest in those with the MLL3 (rs1137721)-CC and TGFβ1 (rs4522809)-AA + GG genotype (OR = 4.38, 95% CI = 0.92-20.83). However, the 55-month median long-term follow-up did not show statistical significance.

CONCLUSION

Carriers of both TT + CT of MLL3 (rs1137721) and AA of TGFβ1 (rs4522809) polymorphisms may be closely related to the development of Stanford type B AD. MLL3 (rs1137721), WBC, and TG/TC were found to be associated with the morbidity of Stanford type B AD. MLL3 (KMT2C) is associated with the TGF-β signaling pathway protein. The risk of Stanford type B AD is related to the interactions of gene-gene and gene-environment.

Calcium promotes vascular smooth muscle cell phenotypic switching in Marfan syndrome

Fibrillin 1 (Fbn1) mutations cause Marfan syndrome (MFS), with aortic root dilatation, dissection, and rupture. Few studies reported the blood calcium and lipid profile of MFS, and the effect of vascular smooth muscle cell (VSMC) phenotypic switching on MFS aortic aneurysm is unclear. Here, we aimed to investigate the role of calcium-related VSMC phenotypic switching in MFS. We retrospectively collected MFS patients' clinical data, performed bioinformatics analysis to screen the enriched biological process in MFS patients and mice, and detected markers of VSMC phenotypic switching on Fbn1^C1039G/+ mice and primary aortic vascular smooth muscle cells. We found that patients with MFS have elevated blood calcium levels and dyslipidemia. Furthermore, the calcium concentration levels were increased with age in MFS mice, accompanied by the promoted VSMC phenotypic switching, and SERCA2 contributed to maintaining the contractile phenotype of VSMCs. This study provides the first evidence that the increased calcium is associated with the promoted VSMC phenotype switching in MFS. SERCA may become a novel therapeutic target for suppressing aneurysm progression in MFS.

Genetic association of lipids and lipid-lowering drug target genes with non-alcoholic fatty liver disease

BACKGROUND

Some observational studies found that dyslipidaemia is a risk factor for non-alcoholic fatty liver disease (NAFLD), and lipid-lowering drugs may lower NAFLD risk. However, it remains unclear whether dyslipidaemia is causative for NAFLD. This Mendelian randomisation (MR) study aimed to explore the causal role of lipid traits in NAFLD and evaluate the potential effect of lipid-lowering drug targets on NAFLD.

METHODS

Genetic variants associated with lipid traits and variants of genes encoding lipid-lowering drug targets were extracted from the Global Lipids Genetics Consortium genome-wide association study (GWAS). Summary statistics for NAFLD were obtained from two independent GWAS datasets. Lipid-lowering drug targets that reached significance were further tested using expression quantitative trait loci data in relevant tissues. Colocalisation and mediation analyses were performed to validate the robustness of the results and explore potential mediators.

FINDINGS

No significant effect of lipid traits and eight lipid-lowering drug targets on NAFLD risk was found. Genetic mimicry of lipoprotein lipase (LPL) enhancement was associated with lower NAFLD risks in two independent datasets (OR₁ = 0.60 [95% CI 0.50-0.72], p₁ = 2.07 × 10^-8; OR₂ = 0.57 [95% CI 0.39-0.82], p₂ = 3.00 × 10^-3). A significant MR association (OR = 0.71 [95% CI, 0.58-0.87], p = 1.20 × 10^-3) and strong colocalisation association (PP.H₄ = 0.85) with NAFLD were observed for LPL expression in subcutaneous adipose tissue. Fasting insulin and type 2 diabetes mediated 7.40% and 9.15%, respectively, of the total effect of LPL on NAFLD risk.

INTERPRETATION

Our findings do not support dyslipidaemia as a causal factor for NAFLD. Among nine lipid-lowering drug targets, LPL is a promising candidate drug target in NAFLD. The mechanism of action of LPL in NAFLD may be independent of its lipid-lowering effects.

FUNDING

Capital's Funds for Health Improvement and Research (2022-4-4037). CAMS Innovation Fund for Medical Sciences (CIFMS, grant number: 2021-I2M-C&T-A-010).

Phenome-wide Mendelian randomization study of plasma triglyceride levels and 2600 disease traits

Background

Causality between plasma triglyceride (TG) levels and atherosclerotic cardiovascular disease (ASCVD) risk remains controversial despite more than four decades of study and two recent landmark trials, STRENGTH, and REDUCE-IT. Further unclear is the association between TG levels and non-atherosclerotic diseases across organ systems.

Methods

Here, we conducted a phenome-wide, two-sample Mendelian randomization (MR) analysis using inverse-variance weighted (IVW) regression to systematically infer the causal effects of plasma TG levels on 2600 disease traits in the European ancestry population of UK Biobank. For replication, we externally tested 221 nominally significant associations (p<0.05) in an independent cohort from FinnGen. To account for potential horizontal pleiotropy and the influence of invalid instrumental variables, we performed sensitivity analyses using MR-Egger regression, weighted median estimator, and MR-PRESSO. Finally, we used multivariable MR (MVMR) controlling for correlated lipid fractions to distinguish the independent effect of plasma TG levels.

Results

Our results identified seven disease traits reaching Bonferroni-corrected significance in both the discovery (p<1.92 × 10-5) and replication analyses (p<2.26 × 10-4), suggesting a causal relationship between plasma TG levels and ASCVDs, including coronary artery disease (OR 1.33, 95% CI 1.24-1.43, p=2.47 × 10-13). We also identified 12 disease traits that were Bonferroni-significant in the discovery or replication analysis and at least nominally significant in the other analysis (p<0.05), identifying plasma TG levels as a novel potential risk factor for nine non-ASCVD diseases, including uterine leiomyoma (OR 1.19, 95% CI 1.10-1.29, p=1.17 × 10-5).

Conclusions

Taking a phenome-wide, two-sample MR approach, we identified causal associations between plasma TG levels and 19 disease traits across organ systems. Our findings suggest unrealized drug repurposing opportunities or adverse effects related to approved and emerging TG-lowering agents, as well as mechanistic insights for future studies.

Funding

RD is supported by the National Institute of General Medical Sciences of the National Institutes of Health (NIH) (R35-GM124836) and the National Heart, Lung, and Blood Institute of the NIH (R01-HL139865 and R01-HL155915).

Genetic Association between the Levels of Plasma Lipids and the Risk of Aortic Aneurysm and Aortic Dissection: A Two-Sample Mendelian Randomization Study

Although a growing number of studies have attempted to uncover the relationship between plasma lipids and the risk of aortic aneurysm (AA), it remains controversial. Meanwhile, the relationship between plasma lipids and the risk of aortic dissection (AD) has not been reported on. We conducted a two-sample Mendelian randomization (MR) analysis to evaluate the potential relationship between genetically predicted plasma levels of lipids and the risk of AA and AD. Summary data on the relationship between genetic variants and plasma lipids were obtained from the UK Biobank and Global Lipids Genetics Consortium studies, and data on the association between genetic variants and AA or AD were taken from the FinnGen consortium study. Inverse-variance weighted (IVW) and four other MR analysis methods were used to evaluate effect estimates. Results showed that genetically predicted plasma levels of low-density lipoprotein cholesterol, total cholesterol, or triglycerides were positively correlated with the risk of AA, and plasma levels of high-density lipoprotein cholesterol were negatively correlated with the risk of AA. However, no causal relationship was found between elevated lipid levels and the risk of AD. Our study revealed a causal relationship between plasma lipids and the risk of AA, while plasma lipids had no effect on the risk of AD.

Bioinformatics-based identification of lipid- and immune-related biomarkers in abdominal aortic aneurysms

Background

Abdominal aortic aneurysm (AAA) manifest as a natural inflammatory process with permanent dilation and terminal rupture. Nevertheless, the pathogenesis of AAA remains a mystery, and treatment is still controversial. Lipid metabolism and immune system are involved in AAA progression, which has been well documented. However, lipid- and immune-related (LIR) biomarkers need to be further elucidated.

Methods

The AAA-related datasets were retrieved from the GEO database, and the datasets were analyzed for differential gene expression by NetworkAnalyst. GO and KEGG pathway enrichment analysis of differentially expressed mRNA (DE-mRNA) was performed using Metscape, and LIR DE-mRNA was further screened. AAA rat model was constructed using porcine pancreatic elastase to verify the differential expression of LIR DE-mRNA.

Results

The GSE47472 and GSE57691 datasets respectively identified 614 (containing 381 down-regulated and 233 up-regulated DE-mRNAs) and 384 (containing 218 down-regulated and 164 up-regulated DE-mRNAs) DE-mRNAs. Intersection and union of DE-mRNAs were 13 and 983, respectively. The main terms involved in the union of DE-mRNAs included "immune system process", "metabolic process", "Chemokine signaling pathway", "hematopoietic cell lineage" and "Cholesterol metabolism". In vivo experiments revealed that LIR DE-mRNAs of PDIA3, TYROBP, and HSPA1A were significantly low expression in AAA abdominal aortic tissues, and HCK and SERPINE1 were significantly high expression, which is consistent with the bioinformatics analysis.

Conclusions

PDIA3, TYROBP, HSPA1A, HCK and SERPINE1 may serve as LIR biomarkers of AAA, which provides new insights and theoretical guidance for the future treatment, early prevention and progression of AAA.

Glycoprotein and Lipoprotein Profiles Assessed by 1H-NMR and Its Relation to Ascending Aortic Dilatation in Bicuspid Aortic Valve Disease

INTRODUCTION

The bicuspid aortic valve (BAV) confers a high risk of ascending aorta dilatation (AAoD), although its progression seems highly variable. Furthermore, the implication of lipoprotein metabolism and inflammation in the mechanisms that underlie AAoD is not fully established. The aim of this study consisted of evaluating the impact of the lipoprotein and glycoprotein profiles in AAOD as well as its progression in BAV aortopathy.

METHODS

Using 1H-nuclear magnetic resonance (1H-NMR), we analyzed and compared the lipoprotein and glycoprotein profiles of plasma samples from 152 BAV patients with dilated and nondilated ascending aorta. Additionally, these profiles were also compared for 119 of these patients who were prospectively followed-up clinically and by echocardiography in the long-term (5 years). Ascending aorta dilation velocity (mm/year) was calculated for this analysis.

RESULTS

Several parameters related to the lipoprotein profile including remnant cholesterol, small LDL and IDL-cholesterol were found to be significantly increased in the dilated group compared to those in the nondilated group. The glycoprotein A-nuclear magnetic resonance (NMR) signal, a novel inflammation biomarker, was also observed to be increased in the dilated group. After performing multivariate analysis, remnant cholesterol remained an independent variable related to AAoD. In the long-term follow-up, proatherogenic lipoprotein parameters were related to ascending aorta dilatation velocity ascending. After a lineal regression analysis, non-HDL particles remained as an independent predictor of ascending aorta dilation velocity.

CONCLUSIONS

Patients with BAV and AAoD presented a more pro-atherogenic profile assessed by 1H-NMR, especially related to triglyceride-rich lipoproteins. This pro-atherogenic profile seems to contribute to the higher growth rate of ascending aorta diameter.

Linking single nucleotide polymorphisms to signaling blueprints in abdominal aortic aneurysms

Abdominal aortic aneurysms (AAA) is a multifactorial complex disease with life-threatening consequences. While Genome-wide association studies (GWAS) have revealed several single nucleotide polymorphisms (SNPs) located in the genome of individuals with AAA, the link between SNPs with the associated pathological signals, the influence of risk factors on their distribution and their combined analysis is not fully understood. We integrated 86 AAA SNPs from GWAS and clinical cohorts from the literature to determine their phenotypical vulnerabilities and association with AAA risk factors. The SNPs were annotated using snpXplorer AnnotateMe tool to identify their chromosomal position, minor allele frequency, CADD (Combined Annotation Dependent Depletion), annotation-based pathogenicity score, variant consequence, and their associated gene. Gene enrichment analysis was performed using Gene Ontology and clustered using REVIGO. The plug-in GeneMANIA in Cytoscape was applied to identify network integration with associated genes and functions. 15 SNPs affecting 20 genes with a CADD score above ten were identified. AAA SNPs were predominantly located on chromosome 3 and 9. Stop-gained rs5516 SNP obtained high frequency in AAA and associated with proinflammatory and vascular remodeling phenotypes. SNPs presence positively correlated with hypertension, dyslipidemia and smoking history. GO showed that AAA SNPs and their associated genes could regulate lipid metabolism, extracellular matrix organization, smooth muscle cell proliferation, and oxidative stress, suggesting that part of these AAA traits could stem from genetic abnormalities. We show a library of inborn SNPs and associated genes that manifest in AAA. We uncover their pathological signaling trajectories that likely fuel AAA development.

Genetic and clinical determinants of abdominal aortic diameter: genome-wide association studies, exome array data and Mendelian randomization study

Progressive dilation of the infrarenal aortic diameter is a consequence of the ageing process and is considered the main determinant of abdominal aortic aneurysm (AAA). We aimed to investigate the genetic and clinical determinants of abdominal aortic diameter (AAD). We conducted a meta-analysis of genome-wide association studies in 10 cohorts (n = 13 542) imputed to the 1000 Genome Project reference panel including 12 815 subjects in the discovery phase and 727 subjects [Partners Biobank cohort 1 (PBIO)] as replication. Maximum anterior-posterior diameter of the infrarenal aorta was used as AAD. We also included exome array data (n = 14 480) from seven epidemiologic studies. Single-variant and gene-based associations were done using SeqMeta package. A Mendelian randomization analysis was applied to investigate the causal effect of a number of clinical risk factors on AAD. In genome-wide association study (GWAS) on AAD, rs74448815 in the intronic region of LDLRAD4 reached genome-wide significance (beta = -0.02, SE = 0.004, P-value = 2.10 × 10-8). The association replicated in the PBIO1 cohort (P-value = 8.19 × 10-4). In exome-array single-variant analysis (P-value threshold = 9 × 10-7), the lowest P-value was found for rs239259 located in SLC22A20 (beta = 0.007, P-value = 1.2 × 10-5). In the gene-based analysis (P-value threshold = 1.85 × 10-6), PCSK5 showed an association with AAD (P-value = 8.03 × 10-7). Furthermore, in Mendelian randomization analyses, we found evidence for genetic association of pulse pressure (beta = -0.003, P-value = 0.02), triglycerides (beta = -0.16, P-value = 0.008) and height (beta = 0.03, P-value < 0.0001), known risk factors for AAA, consistent with a causal association with AAD. Our findings point to new biology as well as highlighting gene regions in mechanisms that have previously been implicated in the genetics of other vascular diseases.

HDL metabolism and functions impacting on cell cholesterol homeostasis are specifically altered in patients with abdominal aortic aneurysm

Background

The etiopathogenesis of abdominal aortic aneurysm (AAA) is still unclarified, but vascular inflammation and matrix metalloproteases activation have a recognized role in AAA development and progression. Circulating lipoproteins are involved in tissue inflammation and repair, particularly through the regulation of intracellular cholesterol, whose excess is associated to cell damage and proinflammatory activation. We analyzed lipoprotein metabolism and function in AAA and in control vasculopathic patients, to highlight possible non-atherosclerosis-related, specific abnormalities.

Methods

We measured fluorometrically serum esterified/total cholesterol ratio, as an index of lecithin-cholesterol acyltransferase (LCAT) activity, and cholesteryl ester transfer protein (CETP) activity in patients referred to vascular surgery either for AAA (n=30) or stenotic aortic/peripheral atherosclerosis (n=21) having similar burden of cardiovascular risk factors and disease. We measured high-density lipoprotein (HDL)-cholesterol efflux capacity (CEC), through the ATP-binding cassette G1 (ABCG1) and A1 (ABCA1) pathways and serum cell cholesterol loading capacity (CLC), by radioisotopic and fluorimetric methods, respectively.

Results

We found higher LCAT (+23%; p &lt; 0.0001) and CETP (+49%; p &lt; 0.0001) activity in AAA sera. HDL ABCG1-CEC was lower (−16%; p &lt; 0.001) and ABCA1-CEC was higher (+31.7%; p &lt; 0.0001) in AAA. Stratification suggests that smoking may partly contribute to these modifications. CEC and CETP activity correlated with CLC only in AAA.

Conclusions

We demonstrated that compared to patients with stenotic atherosclerosis, patients with AAA had altered HDL metabolism and functions involved in their anti-inflammatory and tissue repair activity, particularly through the ABCG1-related intracellular signaling. Clarifying the relevance of this mechanism for AAA evolution might help in developing new diagnostic parameters and therapeutic targets for the early management of this condition.

Genetic insights into therapeutic targets for aortic aneurysms: A Mendelian randomization study

BACKGROUND

As aortic aneurysms (AAs) enlarge, they can become life-threatening if left undiagnosed or neglected. At present, there is a lack of radical treatments for preventing disease progression. Therefore, we aimed to identify effective drug targets that slow the progression of AAs.

METHODS

A Mendelian randomization (MR) analysis was conducted to identify therapeutic targets which are associated with AAs. Summary statistics for AAs were obtained from two datasets: the UK Biobank (2228 cases and 408,565 controls) and the FinnGen study (3658 cases and 244,907 controls). Cis-expression quantitative trait loci (cis-eQTL) for druggable genes were retrieved from the eQTLGen Consortium and used as genetic instrumental variables. Colocalization analysis was performed to determine the probability that single nucleotide polymorphisms (SNPs) associated with AAs and eQTL shared causal genetic variants.

FINDINGS

Four drug targets (BTN3A1, FASN, PLAU, and PSMA4) showed significant MR results in two independent datasets. Proteasome 20S subunit alpha 4 (PSMA4) and plasminogen activator, urokinase (PLAU) in particular, were found to have strong evidence for colocalization with AAs, and abdominal aortic aneurysm in particular. Additionally, except for the association between PSMA4 and intracranial aneurysms, no association between genetically proxied inhibition of PLAU and PSMA4 was detected in increasing the risk of other cardiometabolic risks and diseases.

INTERPRETATION

This study supports that drug-targeting PLAU and PSMA4 inhibition may reduce the risk of AAs.

FUNDING

This work was supported by National Key R&D Program of China (NO. 2017YFC0909400), Nature Science Foundation of China (No. 91839302, 81790624), Project supported by Shanghai Municipal Science and Technology Major Project (Grant No. 2017SHZDZX01), and Tongji Hospital Clinical Research Flagship Program (no. 2019CR207).

Clinical features and prognosis of patients with and without diabetes mellitus undergoing endovascular aortic aneurysm repair

BACKGROUND

This study aimed to compare the clinical features and prognoses of patients with and without diabetes mellitus (DM) who underwent endovascular repair for aortic aneurysm (AA).

METHODS

We analyzed the clinical database of a prospective multicenter study, registering 929 patients who underwent their first endovascular AA repair in Japan between January 2016 and June 2018. The baseline characteristics and prognoses (including all-cause mortality and cardiovascular events) after repair were compared between the DM and non-DM groups. Prognoses were also compared between the groups after propensity score matching.

RESULTS

In total, 226 patients (24.3%) had DM. Compared with non-DM patients, DM patients had higher pack-years of smoking (P = 0.011), higher body mass index (P = 0.009), lower high-density lipoprotein cholesterol levels (P = 0.038), higher triglyceride levels (P = 0.025), and lower left ventricular ejection fraction (P = 0.005). Meanwhile, the low-density lipoprotein cholesterol and blood pressure levels showed no significant intergroup difference (all P > 0.05). DM patients had a higher prevalence of myocardial infarction (P = 0.016), history of coronary revascularization (P = 0.015), and lower extremity artery disease (P = 0.019). Lesion characteristics and procedures were similar between the groups (all P > 0.05). DM patients had a higher risk of all-cause mortality and cardiovascular events than non-DM patients (both P < 0.001). Subsequent propensity score matching also demonstrated that DM patients had a significantly lower rate of overall survival (P = 0.001) and freedom from cardiovascular events (P = 0.010). The Kaplan-Meier estimates at 1 year for the overall survival were 85.6% (95% confidence interval [CI], 80.9% to 90.5%) and 94.3% (95% CI, 91.7% to 97.0%) for patients with and without DM, respectively. The corresponding estimates for freedom from cardiovascular events were 79.8% (95% CI, 74.5% to 85.5%) and 87.7% (95% CI, 84.2% to 91.3%), respectively.

CONCLUSIONS

Among patients undergoing endovascular AA repair, those with DM had more cardiovascular risk factors. DM patients had a higher incidence rate of all-cause mortality and cardiovascular events. Matching analysis indicated that DM per se would be a risk factor for poor prognoses after AA repair.

Genetic Predisposition to Diabetes and Abdominal Aortic Aneurysm: A Two Stage Mendelian Randomisation Study

OBJECTIVE

Observational studies demonstrate an inverse association between type II diabetes and abdominal aortic aneurysm (AAA) for reasons that are unclear. The aim of this study was to clarify the causal association between type II diabetes predisposition and AAA using Mendelian randomisation.

METHODS

Effect estimates for single nucleotide polymorphisms (SNPs) associated with diabetes were obtained from the DIAbetes Meta-ANalysis of Trans-Ethnic association studies (DIAMANTE) consortium to construct a genetic instrumental variable. Corresponding effect estimates for associations of these SNPs with AAA were obtained from the International Aneurysm Consortium comprising six separate AAA genomewide association studies (4 972 cases and 99 858 controls). Mendelian randomisation estimates were calculated using inverse variance, weighted median, and MR-Egger methods, and compared against recently published observational estimates.

RESULTS

A genetic risk score was constructed from 206 SNPs associated with diabetes. All three Mendelian randomisation models showed no effect of genetic liability to diabetes and risk of AAA (inverse variance: odds ratio 1.04 per unit higher log odds, 95% 0.98 - 1.11, p = .19; MR-Egger slope p = .33; weighted median p = .50). Results were similar after excluding the TCF7L2 locus (inverse variance p = .075). Findings from the Mendelian randomisation analysis differed from previous observational reports of an inverse association (pdif < .001).

CONCLUSION

Lifelong genetic predisposition to diabetes does not appear to protect against AAA. These findings differ from traditional epidemiological studies showing an inverse association between diabetes and AAA, for reasons that remain unclear.

Profiling of the full-length transcriptome in abdominal aortic aneurysm using nanopore-based direct RNA sequencing

Abdominal aortic aneurysm (AAA) is a common and serious disease with a high mortality rate, but its genetic determinants have not been fully identified. In this feasibility study, we aimed to elucidate the transcriptome profile of AAA and further reveal its molecular mechanisms through the Oxford Nanopore Technologies (ONT) MinION platform. Overall, 9574 novel transcripts and 781 genes were identified by comparing and analysing the redundant-removed transcripts of all samples with known reference genome annotations. We characterized the alternative splicing, alternative polyadenylation events and simple sequence repeat (SSR) loci information based on full-length transcriptome data, which would help us further understand the genome annotation and gene structure of AAA. Moreover, we proved that ONT methods were suitable for the identification of lncRNAs via identifying the comprehensive expression profile of lncRNAs in AAA. The results of differentially expressed transcript (DET) analysis showed that a total of 7044 transcripts were differentially expressed, of which 4278 were upregulated and 2766 were downregulated among two groups. In the KEGG analysis, 4071 annotated DETs were involved in human diseases, organismal systems and environmental information processing. These pilot findings might provide novel insights into the pathogenesis of AAA and provide new ideas for the optimization of personalized treatment of AAA, which is worthy of further study in subsequent studies.

Addressing dyslipidemic risk beyond LDL-cholesterol

Despite the success of LDL-lowering drugs in reducing cardiovascular disease (CVD), there remains a large burden of residual disease due in part to persistent dyslipidemia characterized by elevated levels of triglyceride-rich lipoproteins (TRLs) and reduced levels of HDL. This form of dyslipidemia is increasing globally as a result of the rising prevalence of obesity and metabolic syndrome. Accumulating evidence suggests that impaired hepatic clearance of cholesterol-rich TRL remnants leads to their accumulation in arteries, promoting foam cell formation and inflammation. Low levels of HDL may associate with reduced cholesterol efflux from foam cells, aggravating atherosclerosis. While fibrates and fish oils reduce TRL, they have not been uniformly successful in reducing CVD, and there is a large unmet need for new approaches to reduce remnants and CVD. Rare genetic variants that lower triglyceride levels via activation of lipolysis and associate with reduced CVD suggest new approaches to treating dyslipidemia. Apolipoprotein C3 (APOC3) and angiopoietin-like 3 (ANGPTL3) have emerged as targets for inhibition by antibody, antisense, or RNAi approaches. Inhibition of either molecule lowers TRL but respectively raises or lowers HDL levels. Large clinical trials of such agents in patients with high CVD risk and elevated levels of TRL will be required to demonstrate efficacy of these approaches.

Long-term Benefits and Harms Associated With Genetic Cholesteryl Ester Transfer Protein Deficiency in the General Population

Importance

The balance between the potential long-term clinical benefits and harms associated with genetic cholesteryl ester transfer protein (CETP) deficiency, mimicking pharmacologic CETP inhibition, is unknown.

Objective

To assess the relative benefits and harms associated with genetic CETP deficiency.

Design, Setting, and Participants

This study examined 2 similar prospective cohorts of the Danish general population, with data on a total of 102 607 participants collected from October 10, 1991, through December 7, 2018.

Exposures

Weighted CETP allele scores.

Main Outcomes and Measures

Incident cardiovascular mortality, ischemic heart disease, myocardial infarction, ischemic stroke, peripheral arterial disease, vascular dementia, Alzheimer disease, all-cause mortality, and age-related macular degeneration (AMD). The study first tested whether a CETP allele score was associated with morbidity and mortality, when scaled to genetically lower levels of non-high-density lipoprotein (HDL) cholesterol (ie, 17 mg/dL), corresponding to the reduction observed for anacetrapib vs placebo in the Randomized Evaluation of the Effects of Anacetrapib Through Lipid-Modification (REVEAL) trial. Second, the study assessed how much of the change in morbidity and mortality was associated with genetically lower levels of non-HDL cholesterol. Finally, the balance between the potential long-term clinical benefits and harms associated with genetic CETP deficiency was quantified. For AMD, the analyses also included higher levels of HDL cholesterol associated with genetic CETP deficiency.

Results

Of 102 607 individuals in the study, 56 559 (55%) were women (median age, 58 years [IQR, 47-67 years]). Multivariable adjusted hazard ratios showed that a genetically lower level of non-HDL cholesterol (ie, 17 mg/dL) was associated with a lower risk of cardiovascular mortality (hazard ratio [HR], 0.77 [95% CI, 0.62-0.95]), ischemic heart disease (HR, 0.80 [95% CI, 0.68-0.95]), myocardial infarction (HR, 0.72 [95% CI, 0.55-0.93]), peripheral arterial disease (HR, 0.80 [95% CI, 0.63-1.02]), and vascular dementia (HR, 0.38 [95% CI, 0.18-0.80]) and an increased risk of AMD (HR, 2.33 [95% CI, 1.63-3.30]) but was not associated with all-cause mortality (HR, 0.91 [95% CI, 0.81-1.02]), ischemic stroke (HR, 1.05 [95% CI, 0.81-1.36]), or Alzheimer disease (HR, 1.25 [95% CI, 0.89-1.76]). When scaled to a higher level of HDL cholesterol, the increased risk of AMD was even larger. A considerable fraction of the lower risk of cardiovascular end points was associated with genetically lower levels of non-HDL cholesterol, while the higher risk of AMD was associated with genetically higher levels of HDL cholesterol. Per 1 million person-years, the projected 1916 more AMD events associated with genetically higher levels of HDL cholesterol was similar to the 1962 fewer events of cardiovascular mortality and myocardial infarction combined associated with genetically lower levels of non-HDL cholesterol.

Conclusions and Relevance

This study suggests that genetic CETP deficiency, mimicking pharmacologic CETP inhibition, was associated with a lower risk of cardiovascular morbidity and mortality, but with a markedly higher risk of AMD.

Association between Lipid Levels and Risk for Different Types of Aneurysms: A Mendelian Randomization Study

BACKGROUND

Although the associations between serum lipid levels and aneurysms have been investigated in epidemiological studies, causality remains unknown. Thus, this study aimed to investigate the causal relationships of serum high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), and triglyceride (TG) levels on five types of aneurysms, using genetic variants associated with four lipid traits as instrumental variables in a Mendelian randomization (MR) analysis.

METHODS

We performed two-sample Mendelian randomization (MR) analyses to evaluate the associations of HDL-C, LDL-C, TC, and TG levels with risks for five types of aneurysms and those of LDL-C- (HMGCR, NPC1L1, PCSK9, CETP, and LDLR) and TG-lowering targets (ANGPTL3 and LPL) with aneurysms.

RESULTS

The sample sizes of the included studies ranged from nearly 80,000 to 410,000. We found inverse associations between genetically predicted HDL-C levels and aortic (OR = 0.74, 95% CI = 0.65-0.85) and abdominal aortic aneurysms (0.58, 0.45-0.75). A 1-SD increase in LDL-C and TC levels was associated with increased risks for aortic (1.41, 1.26-1.58 and 1.36, 1.18-1.56, respectively) and abdominal aortic aneurysms (1.82, 1.48-2.22 and 1.55, 1.25-1.93, respectively). TG levels were significantly associated with aortic (1.36, 1.18-1.56) and lower extremity artery aneurysms (2.76, 1.48-5.14), but limited to cerebral aneurysm (1.23, 1.06-1.42). Secondary analyses revealed a relationship between genetically proxied LDL-C-lowering targets and all types of aneurysms; however, the drug targets remained heterogeneous. We found a weak association between TG-lowering therapies and aortic (ANGPTL3, 0.51, 0.29-0.89) and abdominal aortic aneurysms (LPL, 0.64, 0.44-0.94).

CONCLUSION

According to genetic evidence, lipid dysfunction is a causal risk factor for aneurysms. Lipid-lowering drugs may be a potential effective strategy in preventing and managing aneurysms.

Malondialdehyde-modified HDL particles elicit a specific IgG response in abdominal aortic aneurysm

High Density Lipoprotein (HDL) plays a protective role in abdominal aortic aneurysm (AAA); however, recent findings suggest that oxidative modifications could lead to dysfunctional HDL in AAA. This study aimed at testing the effect of oxidized HDL on aortic lesions and humoral immune responses in a mouse model of AAA induced by elastase, and evaluating whether antibodies against modified HDL can be found in AAA patients. HDL particles were oxidized with malondialdehyde (HDL-MDA) and the changes were studied by biochemical and proteomics approaches. Experimental AAA was induced in mice by elastase perfusion and then mice were treated with HDL-MDA, HDL or vehicle for 14 days. Aortic lesions were studied by histomorphometric analysis. Levels of anti-HDL-MDA IgG antibodies were measured by an in-house immunoassay in the mouse model, in human tissue-supernatants and in plasma samples from the VIVA cohort. HDL oxidation with MDA was confirmed by enhanced susceptibility to diene formation. Proteomics demonstrated the presence of MDA adducts on Lysine residues of HDL proteins, mainly ApoA-I. MDA-modification of HDL abrogated the protective effect of HDL on cultured endothelial cells as well as on AAA dilation in mice. Exposure to HDL-MDA elicited an anti-HDL-MDA IgG response in mice. Anti-HDL-MDA were also detected in tissue-conditioned media from AAA patients, mainly in intraluminal thrombus. Higher plasma levels of anti-HDL-MDA IgG antibodies were found in AAA patients compared to controls. Anti-HDL-MDA levels were associated with smoking and were independent predictors of overall mortality in AAA patients. Overall, MDA-oxidized HDL trigger a specific humoral immune response in mice. Besides, antibodies against HDL-MDA can be detected in tissue and plasma of AAA patients, suggesting its potential use as surrogate stable biomarkers of oxidative stress in AAA.

The Potential Benefits and Costs of an Intensified Approach to Low Density Lipoprotein Cholesterol Lowering in People with Abdominal Aortic Aneurysm

OBJECTIVE

The aims of this study were to assess the incidence of major vascular events (MVE) and peripheral vascular events (PVE) in people with a small asymptomatic abdominal aortic aneurysm (AAA) and model the theoretical benefits and costs of an intensified low density lipoprotein cholesterol (LDL-C) lowering programme.

METHODS

A total of 583 participants with AAAs measuring 30 - 54 mm were included in this study. The control of LDL-C and prescription of lipid lowering drugs were assessed by dividing participants into approximately equal tertiles depending on their year of recruitment into the study. The occurrence of MVE (myocardial infarction, stroke, cardiovascular death, and coronary or non-coronary revascularisation) and PVE (non-coronary revascularisation, AAA repair, and major amputation) were recorded prospectively, and the incidence of these events was calculated using Kaplan-Meier analysis. The relative risk reduction reported for these events in a previous randomised control trial (RCT) was then applied to these figures to model the absolute risk reduction and numbers needed to treat (NTT) that could theoretically be achieved with a mean LDL-C lowering of 1 mmol/L. The maximum allowable expense for a cost effective intensive LDL-C lowering programme was estimated using a cost utility analysis.

RESULTS

At entry, only 28.5% of participants had an LDL-C of < 1.8 mmol/L and only 18.5% were prescribed a high potency statin (atorvastatin 80 mg or rosuvastatin 40 mg). The five year incidences of MVE and PVE were 38.1% and 44.7%, respectively. It was estimated that if the mean LDL-C of the cohort had been reduced by 1 mmol/L, this could have reduced the absolute risk of MVE and PVE by 6.5% (95% CI 4.4 - 8.7; NNT 15) and 5.3% (95% CI 1.4 - 7.5; NNT 19), respectively. It was estimated that the maximum allowable expense for a cost effective LDL-C lowering programme would be between $1 239 AUD (€768) and $1 582 AUD (€981) per person per annum over a five year period.

CONCLUSION

People with a small asymptomatic AAA are at high risk of MVE and PVE. This study provides evidence of the possible benefits and allowable expense for a cost effective intensive LDL-C lowering programme in this population.

Sex-specific normal values and determinants of infrarenal abdominal aortic diameter among non-aneurysmal elderly population

To establish age- and sex-specific distribution of the infrarenal abdominal aortic diameters (IAD) among non-aneurysmal elderly population and to investigate the associations between traditional cardiovascular risk factors and IAD in men and women. We included 4032 participants (mean age 67.2 years; 60.4% women) from the population-based Rotterdam Study, free of cardiovascular disease, who underwent IAD ultrasound assessment between 2009-2014. Linear regression analysis was used to identify determinants of IAD. The medians (inter-quartile range) of absolute IAD and body surface area (BSA)-adjusted IAD were 17.0 (15.0-18.0) mm and 9.3 (8.5-10.2) mm for women and 19.0 (18.0-21.0) mm and 9.4 (8.6-10.3) mm for men, respectively. There was a non-linear relationship between age and IAD. IAD increased steeply with advancing age and up to 70 years. After around 75 years of age, the diameter values reached a plateau. Waist circumference and diastolic blood pressure were associated with larger diameters in both sexes. Body mass index [Effect estimate (95% CI): 0.04 (0.00 to 0.08)], systolic blood pressure [- 0.01(- 0.02 to 0.00)], current smoking [0.35 (0.06 to 0.65)], total cholesterol levels [- 0.21 (- 0.31 to - 0.11)], and lipid-lowering medication [- 0.43 (- 0.67 to - 0.19)] were significantly associated with IAD in women. Sex differences in IAD values diminished after taking BSA into account. The increase in diameters was attenuated after 70 years. Differences were observed in the associations of several cardiovascular risk factors with IAD among men and women.

Systematic review and Meta-Analysis of Mendelian randomisation analyses of Abdominal aortic aneurysms

INTRODUCTION

Mendelian randomisation (MR) has been suggested to be able to overcome biases of observational studies, but no meta-analysis is available on MR studies on abdominal aortic aneurysm (AAA). This systematic review and Meta-analysis examined the evidence of causal risk factors for AAA identified in MR studies.

METHODS

Publicly available databases were systematically searched for MR studies that reported any causal risk factors for AAA diagnosis. Meta-analyses were performed using random effect models and reported as odds ratio (OR) and 95% confidence intervals (CI). Study quality was assessed using a modified version of Strengthening the Reporting of Mendelian Randomisation Studies (STROBE-MR) guidelines.

RESULTS

Sixteen MR studies involving 34,050 patients with AAA and 2,205,894 controls were included. Meta-analyses suggested that one standard deviation increase in high density lipoprotein (HDL) significantly reduced (OR: 0.66, 95% CI: 0.61, 0.72) and one standard deviation increase in low density lipoprotein (LDL) significantly increased the risk (OR: 1.68, 95%, CI: 1.55, 1.82) of AAA. One standard deviation increase in triglycerides did not significantly increase the risk of AAA (OR: 1.21, 95% CI: 0.86, 1.71). Quality assessment suggested that ten and five studies were of low and moderate risk of bias respectively, with one study considered as high risk of bias.

CONCLUSION

This meta-analysis suggests LDL and HDL are positive and negative casual risk factors for AAA.

Peripheral Artery Disease and Abdominal Aortic Aneurysm: The Forgotten Diseases in COVID-19 Pandemic. Results from an Observational Study on Real-World Management

Background and Objectives: It is well established that patients with peripheral artery disease (PAD) as well abdominal aortic aneurysm (AAA) have an increased cardiovascular (CV) mortality. Despite this higher risk, PAD and AAA patients are often suboptimality treated. This study assessed the CV profile of PAD and AAA patients, quantifying the survival benefits of target-based risk-factors modification even in light of the COVID-19 pandemic. Materials and Methods: PAD and AAA patients admitted for any reason to the Vascular Unit from January 2019 to February 2020 were retrospectively analyzed. Biochemical and CV profiles as well as ongoing medical therapies were recorded. Benefits of CV risk-factors control were estimated using the SMART-REACH model. A follow-up visit during the year 2020 was scheduled. Results: A total of 669 patients were included. Of these, 190 showed AAA and 479 PAD at any stage. Only 54% of PAD and 41% of AAA patients were on lipid-lowering drugs with non-optimal low-density lipoprotein (LDL) levels for most of them. A better control of all modifiable CV risk-factors based on the current guidelines would offer an absolute risk reduction of the mean 10-year CV risk by 9% in PAD and 14% in AAA. Unfortunately, the follow-up visit was lost because of COVID-19 limitations. Conclusions: Lipid profiles of PAD and AAA patients were far from guideline-based targets, and medical management was suboptimal. In our center, the COVID-19 pandemic impacted on the strict surveillance required in these very high-risk patients. The achievement of guideline-based therapeutic targets would definitively confer additional significant benefits in reducing the CV risk in these patients.