P2X7 and inflammatory fingerprinting of patients with carotid atherosclerosis and the risk of abdominal aortic aneurysm

Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ministero della Salute, Italia, Rete Cardiologica Nazionale Background Carotid atherosclerosis and abdominal aortic aneurysm (AAA) are co-morbidities [1]. P2X-purinoceptor-7 (P2X7) is expressed both in human AAA and atherosclerotic carotid plaque (CPL) and is instability-associated in CPL [2-4]. P2X7 is functionally related to miR-150 and miR-186 (two microRNA which modulate vascular cell proliferation) [5,6], and may be shed into the bloodstream in correlation with C-reactive protein increase [7]. Little is known about the possible association between AAA risk and circulating P2X7, miR-150 and miR-186 in patients with/without hemodinamically significant CPL. Purpose Our aim is exploring the possible relationship between circulating P2X7, target miRs clinical status and lesion dimensions in patients with CPL and/or AAA. Methods Male patients with AAA and/or CPL were characterized.CPL stenosis was assessed by Ecocolordoppler-TSA. Eligible cohort included 20 patients with AAA undergoing aneurysmectomy [10 with CPL stenosis ≤40% (group A), 10with CPL stenosis >40% (group B)], 10 patients with hemodinamically significant CPL and small or no AAA undergoing endarterectomy (group C) donating blood and vascular samples at surgery. Twelve healthy blood donors (group D) were enrolled as controls. P2X7 protein was evaluated by ELISA. P2X7 gene, miR-150 and miR-186 were determined by RT-qPCR. Results In group A, CPL appeared mainly localized at carotid bulb, in group B extended along branches. P2X7 gene was undetermined into serum and expressed without differences among groups in patient tissues. P2X7 protein was measurable in all serum samples and was lower in group B than in the others (p=0,0117, p=0,0009, p=0,0003 vs. group A, C, D, respectively) and in group C vs. D (p=0,0006). These data differentiated patients with hemodinamically significant CPLs with severe AAA from the other patients and all those with hemodinamically significant CPLs (irrespectively from AAA severity) from healthy individuals. In group B but not in the others, serum P2X7 was linearly associated to platelet concentration. In group C the amounts of P2X7 in CPL tissue and serum were negatively associated, whereas in group A and B the P2X7 levels in AAA tissue and serum were unrelated. The miRs were detected into both serum and tissue and not correlated among them nor with circulating P2X7 protein. The serum miR-186, but not miR-150, was differentially expressed in group A vs. B (p=0,0266) and linearly related to AAA diameter in group B (p=0.0351). P2X7 content and expressed gene (p=0,015, p= 0,023, respectively) and miR expressions (p=0,0418 for miR-186, p=0,0012 for miR-150) were more elevated in AAA vs. CPL tissues, highlighting the vascular heterogenicity. Conclusions Preliminary data suggest a role for P2X7 and miR-186 in profiling patients with hemodinamically significant CPL with/without high risk AAA, deserving further investigations.

Endovascular aneurysm repair at 5 years: does aneurysm diameter predict outcome?

Reduced number and impaired function of circulating endothelial progenitor cells in patients with abdominal aortic aneurysm

Identifying biomarkers for abdominal aortic aneurysms (AAA) is key to understanding their pathogenesis, developing novel targeted therapeutics, and possibly improving patients outcomes and risk of rupture. Here, we identified AAA biomarkers from public databases using single-cell RNA-sequencing, weighted co-expression network (WGCNA), and differential expression analyses. Additionally, we used the multiple machine learning methods to identify biomarkers that differentiated large AAA from small AAA. Biomarkers were validated using GEO datasets. CIBERSORT was used to assess immune cell infiltration into AAA tissues and investigate the relationship between biomarkers and infiltrating immune cells. Therefore, 288 differentially expressed genes (DEGs) were screened for AAA and normal samples. The identified DEGs were mostly related to inflammatory responses, lipids, and atherosclerosis. For the large and small AAA samples, 17 DEGs, mostly related to necroptosis, were screened. As biomarkers for AAA, G0/G1 switch 2 (G0S2) (Area under the curve [AUC] = 0.861, 0.875, and 0.911, in GSE57691, GSE47472, and GSE7284, respectively) and for large AAA, heparinase (HPSE) (AUC = 0.669 and 0.754, in GSE57691 and GSE98278, respectively) were identified and further verified by qRT-PCR. Immune cell infiltration analysis revealed that the AAA process may be mediated by T follicular helper (Tfh) cells and the large AAA process may also be mediated by Tfh cells, M1, and M2 macrophages. Additionally, G0S2 expression was associated with neutrophils, activated and resting mast cells, M0 and M1 macrophages, regulatory T cells (Tregs), resting dendritic cells, and resting CD4 memory T cells. Moreover, HPSE expression was associated with M0 and M1 macrophages, activated and resting mast cells, Tregs, and resting CD4 memory T cells. Additional, G0S2 may be an effective diagnostic biomarker for AAA, whereas HPSE may be used to confer risk of rupture in large AAAs. Immune cells play a role in the onset and progression of AAA, which may improve its diagnosis and treatment.

Introduction: Diameter is currently the only factor used to estimate rupture risk of abdominal aortic aneurysms (AAAs). Many large AAAs, however, do not rupture, and a significant portion of small AAAs do. Our aim was to investigate if simple two-dimensional geometric measurements can improve rupture risk prediction in AAAs, and relate these measurements to biomechanical determinants of AAAs. Methods: Thirty patients with ruptured AAAs (mean age was 77 ± 5 years and 23 were male) and 60 patients (mean age 60 ± 8 years, and 46 were male) with asymptomatic AAAs were included. At the location of the maximal diameter, the diameter, the luminal area and the vessel area were measured. Finite element analysis was used to compute 3D-geometric and biomechanical parameters of the asymptomatic AAAs, using A4 Clinics Software (VASCOPS, Austria). An automatic matching function was used to construct diameter-matched groups. Results: Analysis of all stable AAAs (n=60) and ruptured AAAs (n=30) showed that ruptured AAAs had a significantly larger diameter, 77 ± 15 mm vs. 62 ± 13 mm (p<0.01) and significantly larger luminal area 2281 ± 1964 mm 2 vs. 1059 ± 674 mm 2 (p<0.01). In order to control for diameter as a confounder, two diameter-matched groups, one with ruptured AAAs (n=28) and one with stable AAAs (n=15) were formed (74 ± 12 mm vs 73 ± 11, p = .67). Diameter-matched ruptured AAAs had a larger luminal area (1954 ± 1254 mm 2 vs. 1120 ± 623 mm 2 , p = .02) and a lower relative ILT area (55 ± 24 % vs 68 ± 24%, p= .03). In multivariate regression of 60 asymptomatic AAAs, including the maximal diameter, the luminal area explained the largest amount of variance in the biomechanical rupture risk parameters, followed by the ILT-area. Conclusions: We demonstrate that the luminal area is increased in ruptured AAAs compared to stable AAAs. Further, we show that this finding may in part be explained by a correlation between luminal area and biomechanical rupture risk parameters.

Association between serum testosterone and related hormones and risk of symptomatic abdominal aortic aneurysm in male participants from the UK Biobank.

While the coincident presentation of abdominal aortic aneurysm (AAA) and rectal cancer is relatively rare, it is being encountered with increasing frequency as our population ages. Despite this, a recent survey of 46 general and vascular surgeons revealed a glaring lack of consensus in dealing with this problem [1]. This commentary aims to elucidate the principles of management, address conflicting issues and recommend context-specific treatment guidelines [2]. There is a consensus that with concomitant AAA and rectal cancers, the symptomatic lesion should be treated first [3, 4], and the cancer should be treated first if the AAA is less than 5 cm [1, 5]. Our commentary accepts these two premises and scrutinizes the dilemma posed when both lesions are asymptomatic, and the AAA exceeds 5 cm. While there are ample, anecdotal reports of synchronous and staged treatments of AAA and rectal cancer, there is no evidence of the uniform superiority of one approach. Treating the AAA and cancer simultaneously raises the concern of either bacterial seeding of the graft or the risks associated with prolonged operative time. The arguments against this are that with appropriate bowel preparation, perioperative antibiotics and meticulous operative and anesthetic technique, these complications are avoidable. Those supporting a synchronous approach cite (1) avoiding the risks of a second, major operation and (2) obviating the risk of aneurysm rupture during recovery from colon surgery. Treating the cancer first with associated chemotherapy further raises the possibility of chemotherapyrelated AAA growth and rupture [6]. Fixing the AAA first poses a risk of graft infection during subsequent colon surgery and increases the time to eventual cancer treatment, with any delay in recovery potentially increasing the complications and risks associated with cancer growth. In the absence of evidence supporting a uniform approach to patients with coexistent AAA and rectal cancer, we acknowledge that decisions tend to be made based on surgeon experience and what seems most intuitive. Furthermore, we believe that the recommendations should be strictly individualized. Aneurysm size (an independent predictor of aneurysm rupture), cancer stage, patient co-morbidities and life expectancy based on either co-morbidities or cancer prognosis are all relevant in informing the management priorities The AAA should be treated first in a patient with a large AAA and a small, early-stage cancer. If, however, co-morbidities are prohibitive for the repair of a large juxtarenal AAA, we would suggest that the small cancer be treated first, and the AAA reassessed based on how the patient tolerates the colon surgery. Alternatively, in a healthy patient with few co-morbidities, the coexistence of a pre-obstructing cancer and a large AAA might merit concomitant treatment of both. With a large, non-metastatic cancer and a stable AAA less than 5.5 cm, we would recommend that the cancer be treated first. Both patients presented in this series had retroperitoneal aneurysm repairs first. We do not believe that there is a substantial advantage of the retroperitoneal over a transperitoneal approach in these cases. While the retroperitoneal approach might have a slight early morbidity advantage, this is not sufficient to justify fixing the AAA first in all cases. Finally, with advancing technology and the ever-widening applications of minimally invasive This comment refers to the article doi: 10.1007/s10151-009-0542-y.

Introduction: Abdominal aortic aneurysm (AAA) is an important cardiovascular disease in older adults and rupture of an AAA is associated with high mortality. Although traditional cardiovascular risk factors have been associated with the risk of AAA, their importance in the etiology of AAA is not well established, partly due to limited data for asymptomatic AAA from large prospective studies with a long follow up. The objective of this study was to prospectively assess the association between mid-life atherosclerotic disease risk factors and later-life asymptomatic AAA in the ARIC Study, a large, community-based cohort. Methods: Risk factors were measured at baseline, at 45-64 years of age, in 1987-1989. Abdominal aortic ultrasound was conducted in 2011-2013. Ultrasound images with maximal infrarenal abdominal aortic diameter (IAD) ≥ 28 mm were over-read by radiologists. Diagnosis of asymptomatic AAA was made in the over-reading based on IAD ≥ 30 mm. Participants who had a history of repair for abdominal aorta or were identified as clinical AAAs via previous hospital discharge diagnoses were excluded. Multivariable logistic regression models were used to estimate the association of baseline risk factors with AAA risk. Results: A total of 113 asymptomatic AAAs were ascertained in 5,904 participants (78% whites) who had an abdominal ultrasound exam (prevalence=1.9%). Age, male gender, white race, smoking, height, total, HDL, and LDL cholesterols, triglycerides, white blood cell count, and fibrinogen were risk factors for asymptomatic AAA (Table). BMI, diabetes, alcohol consumption, hypertension, and peripheral artery disease were not associated with AAA. In multivariable adjustment that included the significant risk factors, age, smoking, height, LDL or total cholesterol, white blood cell count, and fibrinogen remained independently associated with AAA risk (p<0.05). Conclusions: Several lifestyle and clinical variables measured in middle-age were associated with risk of asymptomatic AAA during a long follow up.

Background: Abdominal aortic aneurysm (AAA) is a potentially lethal vasculopathy that shares multiple risk factors with conventional atherosclerotic disease, including advanced age, male sex, hypertension, and smoking. However, it is still debated whether subclinical atherosclerosis is an independent risk factor for AAA. Hypothesis: Subclinical carotid atherosclerosis is positively associated with future risk of AAA, independent of shared cardiovascular risk factors. Methods: We included 15,363 ARIC participants (74% whites) who had measures of carotid ultrasound at baseline (1987-89) at 45-64 years of age. Carotid intima-media thickness (cIMT) was measured bilaterally in the common carotid artery, carotid bifurcation, and internal carotid artery. Mean cIMT was estimated by combining the averages of cIMT measures at the 6 carotid sites. The presence of atherosclerotic plaque at any of the 6 segments was defined based on wall thickness ≥1.5 mm, or the presence of luminal encroachment or irregular intimal surface, or characteristics of arterial wall structural heterogeneity. Clinical AAAs were ascertained through hospital discharge diagnoses and death certificates through 2010. We used Cox proportional hazard models to examine the association between baseline carotid ultrasound measures and subsequent occurrence of clinical AAA. Results: In the total study sample (age 54±6 years, 45% men), the median (25 th to 75 th percentiles) cIMT at baseline was 0.71 (0.62 to 0.82) mm. Over an average of 21 years of follow up, a total of 392 clinical AAAs (74% male and 85% Whites) were ascertained. After adjustment for age, sex and race, participants in the highest quartile of baseline cIMT had 2.25 times higher risk of AAA (95% CI: 1.81, 2.79) compared to those in the lower 75 percentile. The presence of carotid atherosclerotic plaque at baseline was associated with 1.77 times increased risk of AAA (95% CI: 1.44, 2.17) after adjustment for age, sex and race. The associations for cIMT and atherosclerotic plaque remained significant after additional adjustment for baseline height, pack-years of smoking, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, and hypertension: HR=1.66 (95% CI: 1.32, 2.08) for cIMT quartile 4 vs lower 75 percentile and 1.34 (95% CI: 1.08, 1.66) for presence of carotid atherosclerotic plaque. Further exclusion of participants with history of coronary heart disease or stroke at baseline slightly attenuated but did not abolish the associations of cIMT and atherosclerotic plaque with AAA (p<0.05 after the exclusions). Conclusion: Our study findings suggest that subclinical carotid atherosclerosis in middle-age is independently associated with future risk of clinical AAA.

The premise of the Vascular Services Quality Improvement Programme (VSQIP) in management of patients with asymptomatic large abdominal aortic aneurysms (AAA) is reducing mortality from ruptured AAA in a sustainable way without introducing excessive procedure related mortality. Inevitably a proportion of patients are deemed unfit for elective repair. The aim of this study was to report outcomes of patients who were referred with large asymptomatic AAAs including those turned down for elective repair and identify independent risk factors for being turned down for elective open or endovascular repair of AAA. Consecutive patients referred to a regional vascular center with a large AAA (greater than 55 mm) between 1st January 2008 and 31st March 2018 were included. All patients underwent the nationally agreed VSQIP pathway which included preoperative cardio-pulmonary exercise testing and contrast enhanced CT scan of aorta. The decision to repair and the modality of repair were made through a Multi-Disciplinary Team MDT process on each patient. Patients were classified into two groups; those managed non-operatively and those offered elective repair. Survival was assessed using Kaplan-Meier analysis. Factors associated with non-operative management were examined using multivariate analysis. A total of 876 patients of whom 768 were men and 108 were women with a mean age of 74 years (SD: 7.2) and a diagnosis of a large asymptomatic AAA were assessed. One hundred and seventy-four patients (19.9%) were turned down for elective repair and 702 (80.1%) underwent repair [Open: 244(34.8%), EVAR: 458 (65.2%] with perioperative and 30 day mortality of 1.13% (8 patients). Median duration of follow-up was 1530 days (51 months), (inter quartile range: 1714 days). Patients who underwent repair had significantly higher survival rates compared with those who were turned down (P<0.0001). Risk factors for being turned down for elective AAA included anaerobic threshold <8 mL kg-1 min-1 [OR: (95% CI): 2.27 (1.31-3.92)], (P=0.0005), Age>80 yrs. [OR (95% CI): 1.32 (1.012-1.52], (P=0.0203), complex aneurysm morphology [OR (95% CI): 3.70 (2.82-4.87], (P<0.0001), Female gender: [OR: (95% CI): 2.41 (1.32-3.92)], (P<0.0001) and being classed high or very high risk for open AAA repair OR: (95% CI): 6.48 (4.01-10.49)], (P<0.0001). A significant cohort of patients with large asymptomatic AAA is turned down for elective AAA repair. These patients appear to have significantly lower survival rates than those who are treated. Information on patients turned down for elective AAA repair should be routinely reported.

α-Tocopherol (vitamin E) and β-carotene supplementation does not affect the risk for large abdominal aortic aneurysm in a controlled trial

Introduction: Abdominal aortic aneurysm (AAA) is one of the leading causes of death in the United States. Observational epidemiological studies demonstrated that circulating level of LDL cholesterol is positively associated with AAA risk. However, a causal link between LDL and risk of AAA is still unclear. Hypothesis: There is a causal relationship between plasma LDL and risk of AAA, which can be demonstrated by a Mendelian randomization (MR) approach. Methods: Using a gene score for LDL as an instrumental variable (IV), we conducted a large MR study to investigate the association between plasma level of LDL and risk of AAA in 8,967 European Americans in the ARIC Study. Twelve SNPs that were reported in a published genome-wide association study for LDL and not associated with other lipids or total cholesterol (TC) were selected. A weighted LDL gene score was created as the sum of the number of risk alleles of the selected SNPs multiplied by the SNP-specific effect size on LDL obtained from the literature and then divided by the total number of SNPs. For participants who took antihyperlipidemic medication, a constant was added to their plasma LDL value to account for the effect of medication. A total of 262 clinical AAA cases were ascertained through hospital discharge diagnoses or death certificates during 23 years of follow-up. The IV-predicted risk for AAA per 1 SD increment of LDL was assessed using an IV probit model adjusted for age, sex, field center, and 10 principal components to account for population stratification. A probit regression model adjusted for known risk factors and other lipids was also performed to confirm the association between LDL and AAA risk at the phenotype level. Results: Using the LDL gene score as an IV for LDL, a positive association was observed between plasma LDL and the predicted risk of AAA. Each 1 SD increase in LDL (instrumented by the LDL gene score) was associated with an average increase of 10% (95% CI=0.1%- 20%) in the risk of AAA. The strength of the LDL gene score as an IV was adequate (F-statistic = 20), and this score was not related to other risk factors for AAA, including other lipids. Similar results were observed after we removed participants who took antihyperlipidemic medications. The positive association based on the LDL gene score was concordant in direction with the association between LDL level and AAA without gene score (average increase in the risk of AAA per 1 SD increment in LDL = 0.6%, 95%CI=0.3 %-1%). We conducted a sensitivity analysis by adding SNPs related to TC. This new score was marginally correlated with triglycerides and reduced the adequacy of MR model to below statistical significance. Conclusion: Our finding supports a causal relationship between plasma level of LDL and AAA risk, with higher LDL level leading to a higher AAA risk.

The increasing age of the population has led to the more common occurrence of multi-organ disease. Colorectal cancer (CRC) and abdominal aortic aneurysm (AAA) in the same patient is a difficult management problem. Over 10 years, 23 patients with CRC and AAA were treated at Concord Hospital. The management and outcome of these patients was reviewed to identify an optimum plan for patients with both conditions. The average age of patients was 71 years, ranging from 52 to 90 years. There was only one female patient in the series. In 19 of the patients, the AAA and CRC were synchronous, while in the other four patients the AAA and CRC were remote events. Within the group of patients with synchronous AAA and CRC. 12 had the diagnosis of both conditions made pre-operatively. However, in seven cases an unexpected AAA or CRC was found at operation for the other condition. Sixteen patients underwent resection of the CRC, while only eight underwent repair of the AAA. There were three deaths following CRC resection, two following AAA resection, and one following simultaneous CRC resection and AAA repair. Two of 10 patients with large (> 6 cm) AAA, who underwent CRC resection, ruptured the AAA in the postoperative period. A further patient ruptured 10 months following CRC resection. Colorectal cancer was given priority over AAA when these conditions were found simultaneously. The present study suggests that a large AAA (> 6 cm) should be either given preferential treatment, or resected simultaneously, in view of the high risk of rupture.

Exercise, Vascular Health, and Abdominal Aortic Aneurysms

Introduction: Abdominal aortic aneurysm (AAA) is an important manifestation of vascular disease in older age and rupture of an AAA is a life threatening condition. Traditional atherosclerotic disease risk factors, particularly male sex, smoking and hypertension, are known to contribute to the etiology of AAA. However, epidemiologic studies of AAA have often been cross-sectional, and few have employed a prospective cohort design, especially with long follow-up. The objective of this study was to prospectively assess the association between atherosclerotic disease risk factors and hospitalized AAA in 15,722 participants (68% whites) of the ARIC study, a large, community-based cohort. Methods: Risk factors were measured at baseline at 45-64 year of age. Clinical AAAs were ascertained through hospital discharge diagnoses or death certificates. Over 15 years of follow-up, a total of 265 AAAs (85.3% whites) were identified, including repair procedures, AAA rupture or dissection, and incidental detection. Multivariable Cox proportional hazard models were used to estimate the association of risk factors with the risk of future AAA. Results: Consistent with the literature from prospective studies, we identified age, male gender, white race, smoking, height, total and HDL cholesterols, triglycerides, white blood cell count, and hypertension as risk factors for AAA (Table). In addition, LDL-C, fibrinogen, and peripheral artery disease that were previously reported only in cross-sectional case-control studies were also strongly associated with AAA (Table). Body mass index, diabetes, and alcohol consumption were not associated with AAA occurrence. Conclusions: Several lifestyle and clinical variables measured in middle-age were strong risk factors for future AAA during a long follow-up.