Age-specific sex differences in intravascular ultrasound based coronary atherosclerotic plaque characteristics.

Insights in age- and sex-specific coronary atherosclerotic plaque characteristics may contribute to a better understanding of coronary artery disease and, ultimately, to its prevention and treatment. In 307 women and 406 men aged 20 to 90 years undergoing intravascular ultrasound imaging, sex-based differences in coronary atherosclerotic plaque characteristics were mainly present in younger patients, while these differences were less pronounced at advanced age.

Burden of risk factors in women and men with unrecognised myocardial infarction: a systematic review and meta-analysis.

AIMS: Unrecognised myocardial infarction (MI) is a MI that remains undetected in the acute phase and is associated with an unfavourable prognosis. With this systematic review and meta-analysis, we evaluated the burden of cardiovascular risk factors in individuals with unrecognised MI. METHODS AND RESULTS: We searched general population-based cohort studies diagnosing unrecognised MI by electrocardiogram or myocardial imaging up to 24 November 2023. Pooled mean differences (MD) or risk ratios (RR) with 95% confidence intervals (CI) were determined, and random-effects meta-analyses were performed. Fourteen cohort studies were included involving 200,450 individuals (mean age 62.8±9.9 years, 56.0% women), among which 4,322 (2.2%) experienced unrecognised MI (mean age 66.3±8.2 years, 47.8% women) and 4,653 (2.1%) recognised MI (mean age 68.5±7.3 years, 33.8% women). Compared to individuals without MI, those with unrecognised MI had higher body mass index (MD 0.27, 95% CI 0.16-0.39) and systolic blood pressure (MD 4.48, 95% CI 2.81-6.15), and higher prevalence of hypertension (RR 1.27, 95% CI 1.06-1.51) and diabetes mellitus (RR 1.67, 95% CI 1.36-2.06). Furthermore, individuals with unrecognised MI had lower prevalence of hypertension (RR 0.92, 95% CI 0.88-0.97) and diabetes mellitus (RR 0.80, 95% CI 0.70-0.92). CONCLUSION: Individuals with unrecognised MI are characterised by a substantial burden of metabolic risk factors. Our findings suggest insufficient recognition and management of cardiovascular risk factors among individuals with unrecognised MI.

Tobacco smoking is associated with sex- and plaque-type specific upregulation of CRLF1 in atherosclerotic lesions.

BACKGROUND AND AIMS: Tobacco smoking is a known risk factor for atherosclerotic disease, with more elevated risks in women compared to men. We hypothesized that atherosclerotic plaques from smokers show different gene expression patterns compared to non-smokers, in a sex-specific manner. METHODS: Gene expression data of 625 carotid plaques (151 females and 474 males) were analyzed for differential gene expression between current smokers (n = 226) and non-smokers (n = 399). All analyses were stratified by sex and by molecular plaque characteristics. Finally, we projected the activity of gene regulatory networks and utilized single-cell transcriptomics from 38 plaques (26 males and 12 females) to interpret the sex- and plaque-type specific signals. RESULTS: We observed higher expression levels of CRLF1 gene in atherosclerotic plaques from smokers compared to non-smokers (log2FC = 0.48, FDR = 0.012). CRLF1 upregulation was interacting with sex (p = 0.01) and was more pronounced in females (log2FC = 0.93, p = 1.53E-05) compared to males (log2FC = 0.35, p = 0.0018). Through single-cell RNA-seq analysis, we identified the highest CRLF1 expression within the transitioning and synthetic smooth muscle cell populations. CRLF1 expression was increased in fibro-inflammatory and fibro-cellular plaque types. Gene annotations pointed to increased expression of CRLF1 in networks with extracellular matrix related genes. CONCLUSIONS: Atherosclerotic plaques from current smokers show sex-dependent upregulation of smooth muscle cell gene CRLF1. This may explain the different contributions of smoking to cardiovascular risk in females.

The Diagnostic Value of ECG Characteristics for Vasospastic and Microvascular Angina: A Systematic Review.

BACKGROUND: Coronary vascular dysfunction comprises VSA and/or MVA and is more common in women than in men with angina without obstructive coronary artery disease (ANOCA). Invasive coronary function testing is considered the reference test for diagnosis, but its burden on patients is large. We aimed to investigate the potential of electrocardiography (ECG) as noninvasive marker for vasospastic angina (VSA) and microvascular angina (MVA) diagnosis. METHODS: We systematically screened Pubmed and EMBASE databases for studies reporting on ECG characteristics in ANOCA patients with (a suspicion of) coronary vascular dysfunction. We assessed study quality using QUADAS-2. We extracted data on diagnostic values of different ECG characteristics and analyzed whether the studies were sex-stratified. RESULTS: Thirty publications met our criteria, 13 reported on VSA and 17 on MVA. The majority addressed repolarization-related ECG parameters. Only 1 of the 13 VSA papers and 4 of the 17 MVA papers showed diagnostic accuracy measures of the ECG characteristics. The presence of early repolarization, T-wave alternans, and inverted U waves showed of predictive value for VSA diagnosis. The QTc interval was predictive for MVA diagnosis in all six studies reporting on QTc interval. Sex-stratified results were reported in only 5 of the 30 studies and 3 of those observed sex-based differences. CONCLUSIONS: ECG features are not widely evaluated in diagnostic studies for VSA and MVA. Those features predictive for VSA and MVA diagnosis mostly point to repolarization abnormalities and may contribute to noninvasive risk stratification.

Identifying plasma proteomic signatures from health to heart failure, across the ejection fraction spectrum.

Circulating proteins may provide insights into the varying biological mechanisms involved in heart failure (HF) with preserved ejection fraction (HFpEF) and reduced ejection fraction (HFrEF). We aimed to identify specific proteomic patterns for HF, by comparing proteomic profiles across the ejection fraction spectrum. We investigated 4210 circulating proteins in 739 patients with normal (Stage A/Healthy) or elevated (Stage B) filling pressures, HFpEF, or ischemic HFrEF (iHFrEF). We found 2122 differentially expressed proteins between iHFrEF-Stage A/Healthy, 1462 between iHFrEF-HFpEF and 52 between HFpEF-Stage A/Healthy. Of these 52 proteins, 50 were also found in iHFrEF vs. Stage A/Healthy, leaving SLITRK6 and NELL2 expressed in lower levels only in HFpEF. Moreover, 108 proteins, linked to regulation of cell fate commitment, differed only between iHFrEF-HFpEF. Proteomics across the HF spectrum reveals overlap in differentially expressed proteins compared to stage A/Healthy. Multiple proteins are unique for distinguishing iHFrEF from HFpEF, supporting the capacity of proteomics to discern between these conditions.

IL-1ß Inhibition Partially Negates the Beneficial Effects of Diet-Induced Atherosclerosis Regression in Mice.

BACKGROUND: Thromboembolic events secondary to rupture or erosion of advanced atherosclerotic lesions is the global leading cause of death. The most common and effective means to reduce these major adverse cardiovascular events, including myocardial infarction and stroke, is aggressive lipid lowering via a combination of drugs and dietary modifications. However, we know little regarding the effects of reducing dietary lipids on the composition and stability of advanced atherosclerotic lesions, the mechanisms that regulate these processes, and what therapeutic approaches might augment the benefits of lipid lowering. METHODS: Smooth muscle cell lineage-tracing Apoe-/- mice were fed a high-cholesterol Western diet for 18 weeks and then a zero-cholesterol standard laboratory diet for 12 weeks before treating them with an IL (interleukin)-1ß or control antibody for 8 weeks. We assessed lesion size and remodeling indices, as well as the cellular composition of aortic and brachiocephalic artery lesions, indices of plaque stability, overall plaque burden, and phenotypic transitions of smooth muscle cell and other lesion cells by smooth muscle cell lineage tracing combined with single-cell RNA sequencing, cytometry by time-of-flight, and immunostaining plus high-resolution confocal microscopic z-stack analysis. RESULTS: Lipid lowering by switching Apoe-/- mice from a Western diet to a standard laboratory diet reduced LDL cholesterol levels by 70% and resulted in multiple beneficial effects including reduced overall aortic plaque burden, as well as reduced intraplaque hemorrhage and necrotic core area. However, contrary to expectations, IL-1ß antibody treatment after diet-induced reductions in lipids resulted in multiple detrimental changes including increased plaque burden and brachiocephalic artery lesion size, as well as increasedintraplaque hemorrhage, necrotic core area, and senescence as compared with IgG control antibody-treated mice. Furthermore, IL-1ß antibody treatment upregulated neutrophil degranulation pathways but downregulated smooth muscle cell extracellular matrix pathways likely important for the protective fibrous cap. CONCLUSIONS: Taken together, IL-1ß appears to be required for the maintenance of standard laboratory diet-induced reductions in plaque burden and increases in multiple indices of plaque stability.

Diabetes and risk of acute coronary syndrome in callers with chest discomfort: Cross-sectional study in out-of-hours primary care.

AIMS: We investigated the differences in prevalence of acute coronary syndrome (ACS) by presence versus absence of diabetes in males and females with chest discomfort who called out-of-hours primary care (OHS-PC). METHODS: A cross-sectional study performed in the Netherlands. Patients who called the OHS-PC in the Utrecht region, the Netherlands between 2014 and 2017 with acute chest discomfort were included. We compared those with diabetes with those without diabetes. Multivariable logistic regression was used to determine the relation between diabetes and (i) high urgency allocation and (ii) ACS. RESULTS: Of the 2,195 callers with acute chest discomfort, 180 (8.2%) reported having diabetes. ACS was present in 15.3% of males (22.0% in those with diabetes) and 8.4% of females (18.8% in those with diabetes). Callers with diabetes did not receive a high urgency more frequently (74.4% vs. 67.8% (OR: 1.38; 95% CI 0.98-1.96). However, such callers had a higher odds for ACS (OR: 2.17; 95% CI 1.47-3.19). These differences were similar for females and males. CONCLUSIONS: Diabetes holds promise as diagnostic factor in callers to OHS-PC with chest discomfort. It might help triage in this setting given the increased risk of ACS in those with diabetes.

Atherosclerotic Plaque Epigenetic Age Acceleration Predicts a Poor Prognosis and Is Associated With Endothelial-to-Mesenchymal Transition in Humans.

BACKGROUND: Epigenetic age estimators (clocks) are predictive of human mortality risk. However, it is not yet known whether the epigenetic age of atherosclerotic plaques is predictive for the risk of cardiovascular events. METHODS: Whole-genome DNA methylation of human carotid atherosclerotic plaques (n=485) and of blood (n=93) from the Athero-Express endarterectomy cohort was used to calculate epigenetic age acceleration (EAA). EAA was linked to clinical characteristics, plaque histology, and future cardiovascular events (n=136). We studied whole-genome DNA methylation and bulk and single-cell transcriptomics to uncover molecular mechanisms of plaque EAA. We experimentally confirmed our in silico findings using in vitro experiments in primary human coronary endothelial cells. RESULTS: Male and female patients with severe atherosclerosis had a median chronological age of 69 years. The median epigenetic age was 65 years in females (median EAA, -2.2 [interquartile range, -4.3 to 2.2] years) and 68 years in males (median EAA, -0.3 [interquartile range, -2.9 to 3.8] years). Patients with diabetes and a high body mass index had higher plaque EAA. Increased EAA of plaque predicted future events in a 3-year follow-up in a Cox regression model (univariate hazard ratio, 1.7; P=0.0034) and adjusted multivariate model (hazard ratio, 1.56; P=0.02). Plaque EAA predicted outcome independent of blood EAA (hazard ratio, 1.3; P=0.018) and of plaque hemorrhage (hazard ratio, 1.7; P=0.02). Single-cell RNA sequencing in plaque samples from 46 patients in the same cohort revealed smooth muscle and endothelial cells as important cell types in plaque EAA. Endothelial-to-mesenchymal transition was associated with EAA, which was experimentally confirmed by TGFß-triggered endothelial-to-mesenchymal transition inducing rapid epigenetic aging in coronary endothelial cells. CONCLUSIONS: Plaque EAA is a strong and independent marker of poor outcome in patients with severe atherosclerosis. Plaque EAA was linked to mesenchymal endothelial and smooth muscle cells. Endothelial-to-mesenchymal transition was associated with EAA, which was experimentally validated. Epigenetic aging mechanisms may provide new targets for treatments that reduce atherosclerosis complications.

Non-invasive vascular measures as prognostic predictors for older patients with non-ST elevation acute coronary syndrome.

BACKGROUND: Adverse cardiac events are common in older patients with non-ST elevation acute coronary syndrome (NSTEACS), yet prognostic predictors are still lacking. This study investigated the long-term prognostic significance of non-invasive measures including endothelial function, carotid intima-media thickness (CIMT), and vascular stiffness in older NSTEACS patients referred for invasive treatment. METHODS: NSTEACS patients aged 75 years and older recruited to a multicentre cohort study (NCT01933581) were assessed for baseline endothelial function using endoPAT logarithm of reactive hyperemia index (LnRHI), CIMT using B-mode ultrasound, and vascular stiffness using carotid-femoral pulse wave velocity (cfPWV). Long-term outcomes included major adverse cardiovascular events (MACE), a composite of death, reinfarction, urgent revascularization, stroke/transient ischemic attack, and significant bleeding. RESULTS: Recruitment resulted in 214 patients assessed for LnRHI, 190 patients assessed for CIMT and 245 patients assessed for cfPWV. For LnRHI group (median follow-up 4.73 years [IQR: 1.41-5.00]), Cox regression analysis revealed a trend towards increased risk of MACE (HR: 1.24 [95% CI: 0.80-1.93]; P  = 0.328) and mortality (HR: 1.49 [95% CI: 0.86-2.59]; P  = 0.157), but no significance was reached. No difference for other components of MACE was found. For CIMT group (median follow up 4.74 years [IQR: 1.55-5.00]), no statistically significant difference in MACE was found (HR: 0.92 [95% CI: 0.53-1.59]; P  = 0.754). Similarly, for cfPWV group (median follow-up 4.96 years [IQR: 1.55-5.00]), results did not support prognostic significance (for MACE, HR: 0.95 [95% CI: 0.65-1.39]; P  = 0.794). CONCLUSION: Endothelial function, CIMT and vascular stiffness were proven unsuitable as strong prognostic predictors in older patients with NSTEACS. CLINICAL TRIAL REGISTRATION: NCT01933581.

ANOCA patients with and without coronary vasomotor dysfunction present with limited electrocardiographic remodeling.

Background: Coronary vasomotor dysfunction (CVDys) comprises coronary vasospasm (CVS) and/or coronary microvascular dysfunction (CMD) and is highly prevalent in patients with angina and non-obstructive coronary artery disease (ANOCA). Invasive coronary function testing (CFT) to diagnose CVDys is becoming more common, enabling pathophysiologic research of CVDys. This study aims to explore the electrophysiological characteristics of ANOCA patients with CVDys. Methods: We collected pre-procedural 12-lead electrocardiograms of ANOCA patients with CVS (n = 35), CMD (n = 24), CVS/CMD (n = 26) and patients without CVDys (CFT-, n = 23) who participated in the NL-CFT registry and underwent CFT. Heart axis and conduction times were compared between patients with CVS, CMD or CVS/CMD and patients without CVDys. Results: Heart axis, heart rate, PQ interval and QRS duration were comparable between the groups. A small prolongation of the QT-interval corrected with Bazett (QTcB) and Fridericia (QTcF) was observed in patients with CVDys compared to patients without CVDys (CVS vs CFT-: QTcB = 422 ± 18 vs 414 ± 18 ms (p = 0.14), QTcF = 410 ± 14 vs 406 ± 12 ms (p = 0.21); CMD vs CFT-: QTcB = 426 ± 17 vs 414 ± 18 ms (p = 0.03), QTcF = 413 ± 11 vs 406 ± 12 ms (p = 0.04); CVS/CMD vs CFT-: QTcB = 424 ± 17 vs 414 ± 18 ms (p = 0.05), QTcF = 414 ± 14 vs 406 ± 12 ms (p = 0.04)). Conclusions: Pre-procedural 12-lead electrocardiograms were comparable between patients with and without CVDys undergoing CFT except for a slightly longer QTc interval in patients with CVDys compared to patients without CVDys, suggesting limited cardiac remodeling in patients with CVDys.

Shortness of breath as a diagnostic factor for acute coronary syndrome in male and female callers to out-of-hours primary care.

OBJECTIVE: Chest discomfort and shortness of breath (SOB) are key symptoms in patients with acute coronary syndrome (ACS). It is, however, unknown whether SOB is valuable for recognising ACS during telephone triage in the out-of-hours primary care (OHS-PC) setting. METHODS: A cross-sectional study performed in the Netherlands. Telephone triage conversations were analysed of callers with chest discomfort who contacted the OHS-PC between 2014 and 2017, comparing patients with SOB with those who did not report SOB. We determine the relation between SOB and (1) High urgency allocation, (2) ACS and (3) ACS or other life-threatening diseases. RESULTS: Of the 2195 callers with chest discomfort, 1096 (49.9%) reported SOB (43.7% men, 56.3% women). In total, 15.3% men (13.2% in those with SOB) and 8.4% women (9.2% in those with SOB) appeared to have ACS. SOB compared with no SOB was associated with high urgency allocation (75.9% vs 60.8%, OR: 2.03; 95% CI 1.69 to 2.44, multivariable OR (mOR): 2.03; 95% CI 1.69 to 2.44), but not with ACS (10.9% vs 12.0%; OR: 0.90; 95% CI 0.69 to 1.17, mOR: 0.91; 95% CI 0.70 to 1.19) or 'ACS or other life-threatening diseases' (15.0% vs 14.1%; OR: 1.07; 95% CI 0.85 to 1.36, mOR: 1.09; 95% CI 0.86 to 1.38). For women the relation with ACS was 9.2% vs 7.5%, OR: 1.25; 95% CI 0.83 to 1.88, and for men 13.2% vs 17.4%, OR: 0.72; 95% CI 0.51 to 1.02. For 'ACS or other life-threatening diseases', this was 13.0% vs 8.5%, OR: 1.60; 95% CI 1.10 to 2.32 for women, and 7.5% vs 20.8%, OR: 0.81; 95% CI 0.59 to 1.12 for men. CONCLUSIONS: Men and women with chest discomfort and SOB who contact the OHS-PC more often receive high urgency than those without SOB. This seems to be adequate in women, but not in men when considering the risk of ACS or other life-threatening diseases.

Association of mild kidney dysfunction with diastolic dysfunction and heart failure with preserved ejection fraction.

AIMS: We aim to investigate the association between kidney dysfunction and left ventricular diastolic dysfunction parameters and heart failure with preserved ejection fraction (HFpEF) and whether this is sex-specific. METHODS AND RESULTS: We included participants from the HELPFul observational study. Outpatient clinical care data, including echocardiography, and an expert panel judgement on HFpEF was collected. Estimated glomerular filtration rate (eGFR) was calculated by creatinine and cystatin C without race. The association between eGFR with E/e', left ventricular mass index, relative wall thickness, and stage C/D heart failure was tested by multivariable adjusted regression models, stratified by sex, reporting odds ratios and 95% confidence intervals (95% confidence interval). We analysed 880 participants, mean age 62.9 (standard deviation: 9.3) years, 69% female. Four hundred six participants had mild (37.6%) kidney dysfunction (eGFR: 60-89 mL/min/1.73 m2 ) or moderate (8.5%) kidney dysfunction (eGFR: 30-59 mL/min/1.73 m2 ). HFpEF was significantly more prevalent in participants with mild and moderate kidney dysfunction (10.3% and 16.0%, respectively) than participants with normal kidney function (3.4%). A lower kidney function was associated with higher E/e' and higher relative wall thickness values. Participants with moderate kidney dysfunction had a higher likelihood of American College of Cardiology/American Heart Association stage C/D HF (odds ratio: 2.07, 95% confidence interval: 1.23, 3.49) than participants with normal kidney functions. CONCLUSIONS: Both mild and moderate kidney dysfunction are independently associated with left ventricular diastolic dysfunction parameters and HFpEF. This association is independent of sex and strongest for moderate kidney dysfunction. Considering mild-to-moderate kidney dysfunction as risk factor for HFpEF may help identify high-risk groups benefiting most from early intervention.

Human Plaque Myofibroblasts to Study Mechanisms of Atherosclerosis.

Background Plaque myofibroblasts are critical players in the initiation and advancement of atherosclerotic disease. They are involved in the production of extracellular matrix, the formation of the fibrous cap, and the underlying lipidic core via modulation processes in response to different environmental cues. Despite clear phenotypic differences between myofibroblast cells and healthy vascular smooth muscle cells, smooth muscle cells are still widely used as a cellular model in atherosclerotic research. Methods and Results Here, we present a conditioned outgrowth method to isolate and culture myofibroblast cells from plaques. We obtained these cells from 27 donors (24 carotid and 3 femoral endarterectomies). We show that they keep their proliferative capacity for 8 passages, are transcriptionally stable, retain donor-specific gene expression programs, and express extracellular matrix proteins (FN1, COL1A1, and DCN) and smooth muscle cell markers (ACTA2, MYH11, and CNN1). Single-cell transcriptomics reveals that the cells in culture closely resemble the plaque myofibroblasts. Chromatin immunoprecipitation sequencing shows the presence of histone H3 lysine 4 dimethylation at the MYH11 promoter, pointing to their smooth muscle cell origin. Finally, we demonstrated that plaque myofibroblasts can be efficiently transduced (>97%) and are capable of taking up oxidized low-density lipoprotein and undergoing calcification. Conclusions In conclusion, we present a method to isolate and culture cells that retain plaque myofibroblast phenotypical and functional capabilities, making them a suitable in vitro model for studying selected mechanisms of atherosclerosis.

The accumulation of erythrocytes quantified and visualized by Glycophorin C in carotid atherosclerotic plaque reflects intraplaque hemorrhage and pre-procedural neurological symptoms.

The accumulation of erythrocyte membranes within an atherosclerotic plaque may contribute to the deposition of free cholesterol and thereby the enlargement of the necrotic core. Erythrocyte membranes can be visualized and quantified in the plaque by immunostaining for the erythrocyte marker glycophorin C. Hence, we theorized that the accumulation of erythrocytes quantified by glycophorin C could function as a marker for plaque vulnerability, possibly reflecting intraplaque hemorrhage (IPH), and offering predictive value for pre-procedural neurological symptoms. We employed the CellProfiler-integrated slideToolKit workflow to visualize and quantify glycophorin C, defined as the total plaque area that is positive for glycophorin C, in single slides of culprit lesions obtained from the Athero-Express Biobank of 1819 consecutive asymptomatic and symptomatic patients who underwent carotid endarterectomy. Our assessment included the evaluation of various parameters such as lipid core, calcifications, collagen content, SMC content, and macrophage burden. These parameters were evaluated using a semi-quantitative scoring method, and the resulting data was dichotomized as predefined criteria into categories of no/minor or moderate/heavy staining. In addition, the presence or absence of IPH was also scored. The prevalence of IPH and pre-procedural neurological symptoms were 62.4% and 87.1%, respectively. The amount of glycophorin staining was significantly higher in samples from men compared to samples of women (median 7.15 (IQR:3.37, 13.41) versus median 4.06 (IQR:1.98, 8.32), p < 0.001). Glycophorin C was associated with IPH adjusted for clinical confounders (OR 1.90; 95% CI 1.63, 2.21; p = < 0.001). Glycophorin C was significantly associated with ipsilateral pre-procedural neurological symptoms (OR:1.27, 95%CI:1.06-1.41, p = 0.005). Sex-stratified analysis, showed that this was also the case for men (OR 1.37; 95%CI 1.12, 1.69; p = 0.003), but not for women (OR 1.15; 95%CI 0.77, 1.73; p = 0.27). Glycophorin C was associated with classical features of a vulnerable plaque, such as a larger lipid core, a higher macrophage burden, less calcifications, a lower collagen and SMC content. There were marked sex differences, in men, glycophorin C was associated with calcifications and collagen while these associations were not found in women. To conclude, the accumulation of erythrocytes in atherosclerotic plaque quantified and visualized by glycophorin C was independently associated with the presence of IPH, preprocedural symptoms in men, and with a more vulnerable plaque composition in both men and women. These results strengthen the notion that the accumulation of erythrocytes quantified by glycophorin C can be used as a marker for plaque vulnerability.

IL-1ß inhibition partially negates the beneficial effects of diet-induced lipid lowering.

Background: Thromboembolic events secondary to rupture or erosion of advanced atherosclerotic lesions are the leading cause of death in the world. The most common and effective means to reduce these major adverse cardiovascular events (MACE), including myocardial infarction (MI) and stroke, is aggressive lipid lowering via a combination of drugs and dietary modifications. However, little is known regarding the effects of reducing dietary lipids on the composition and stability of advanced atherosclerotic lesions, the mechanisms that regulate these processes, and what therapeutic approaches might augment the benefits of lipid lowering. Methods: Smooth muscle cell (SMC)-lineage tracing Apoe-/- mice were fed a Western diet (WD) for 18 weeks and then switched to a low-fat chow diet for 12 weeks. We assessed lesion size and remodeling indices, as well as the cellular composition of aortic and brachiocephalic artery (BCA) lesions, indices of plaque stability, overall plaque burden, and phenotypic transitions of SMC, and other lesion cells by SMC-lineage tracing combined with scRNA-seq, CyTOF, and immunostaining plus high resolution confocal microscopic z-stack analysis. In addition, to determine if treatment with a potent inhibitor of inflammation could augment the benefits of chow diet-induced reductions in LDL-cholesterol, SMC-lineage tracing Apoe-/- mice were fed a WD for 18 weeks and then chow diet for 12 weeks prior to treating them with an IL-1ß or control antibody (Ab) for 8-weeks. Results: Lipid-lowering by switching Apoe-/- mice from a WD to a chow diet reduced LDL-cholesterol levels by 70% and resulted in multiple beneficial effects including reduced overall aortic plaque burden as well as reduced intraplaque hemorrhage and necrotic core area. However, contrary to expectations, IL-1ß Ab treatment resulted in multiple detrimental changes including increased plaque burden, BCA lesion size, as well as increased cholesterol crystal accumulation, intra-plaque hemorrhage, necrotic core area, and senescence as compared to IgG control Ab treated mice. Furthermore, IL-1ß Ab treatment upregulated neutrophil degranulation pathways but down-regulated SMC extracellular matrix pathways likely important for the protective fibrous cap. Conclusions: Taken together, IL-1ß appears to be required for chow diet-induced reductions in plaque burden and increases in multiple indices of plaque stability.

Sex differences in the genetic and molecular mechanisms of coronary artery disease.

Sex differences in coronary artery disease (CAD) presentation, risk factors and prognosis have been widely studied. Similarly, studies on atherosclerosis have shown prominent sex differences in plaque biology. Our understanding of the underlying genetic and molecular mechanisms that drive these differences remains fragmented and largely understudied. Through reviewing genetic and epigenetic studies, we identified more than 40 sex-differential candidate genes (13 within known CAD loci) that may explain, at least in part, sex differences in vascular remodeling, lipid metabolism and endothelial dysfunction. Studies with transcriptomic and single-cell RNA sequencing data from atherosclerotic plaques highlight potential sex differences in smooth muscle cell and endothelial cell biology. Especially, phenotypic switching of smooth muscle cells seems to play a crucial role in female atherosclerosis. This matches the known sex differences in atherosclerotic phenotypes, with men being more prone to lipid-rich plaques, while women are more likely to develop fibrous plaques with endothelial dysfunction. To unravel the complex mechanisms that drive sex differences in CAD, increased statistical power and adjustments to study designs and analysis strategies are required. This entails increasing inclusion rates of women, performing well-defined sex-stratified analyses and the integration of multi-omics data.

Female Gene Networks Are Expressed in Myofibroblast-Like Smooth Muscle Cells in Vulnerable Atherosclerotic Plaques.

BACKGROUND: Women presenting with coronary artery disease more often present with fibrous atherosclerotic plaques, which are currently understudied. Phenotypically modulated smooth muscle cells (SMCs) contribute to atherosclerosis in women. How these phenotypically modulated SMCs shape female versus male plaques is unknown. METHODS: Gene regulatory networks were created using RNAseq gene expression data from human carotid atherosclerotic plaques. The networks were prioritized based on sex bias, relevance for smooth muscle biology, and coronary artery disease genetic enrichment. Network expression was linked to histologically determined plaque phenotypes. In addition, their expression in plaque cell types was studied at single-cell resolution using single-cell RNAseq. Finally, their relevance for disease progression was studied in female and male Apoe-/- mice fed a Western diet for 18 and 30 weeks. RESULTS: Here, we identify multiple sex-stratified gene regulatory networks from human carotid atherosclerotic plaques. Prioritization of the female networks identified 2 main SMC gene regulatory networks in late-stage atherosclerosis. Single-cell RNA sequencing mapped these female networks to 2 SMC phenotypes: a phenotypically modulated myofibroblast-like SMC network and a contractile SMC network. The myofibroblast-like network was mostly expressed in plaques that were vulnerable in women. Finally, the mice ortholog of key driver gene MFGE8 (milk fat globule EGF and factor V/VIII domain containing) showed retained expression in advanced plaques from female mice but was downregulated in male mice during atherosclerosis progression. CONCLUSIONS: Female atherosclerosis is characterized by gene regulatory networks that are active in fibrous vulnerable plaques rich in myofibroblast-like SMCs.

X chromosome inactivation skewing is common in advanced carotid atherosclerotic lesions in females and predicts secondary peripheral artery events.

BACKGROUND AND AIM: Sex differences in atherosclerosis have been described with female plaques being mostly perceived as stable and fibrous. Sex-specific mechanisms such as mosaic loss of the Y chromosome in men have been linked to cardiovascular health. In women, X-linked mechanisms such as X chromosome inactivation (XCI) skewing is common in several tissues. Yet, information on the role of XCI in female atherosclerotic plaques is lacking. Here, we investigated the presence of XCI skewing in advanced atherosclerotic lesions and its association with cardiovascular risk factors, histological plaque data, and clinical data. METHODS: XCI skewing was quantified in 154 atherosclerotic plaque and 55 blood DNA samples of women included in the Athero-Express study. The skewing status was determined performing the HUMARA assay. Then, we studied the relationship of XCI skewing in female plaque and cardiovascular risk factors using regression models. In addition, we studied if plaque XCI predicted plaque composition, and adverse events during 3-years follow-up using Cox proportional hazard models. RESULTS: XCI skewing was detected in 76 of 154 (49.4%) plaques and in 27 of 55 (67%) blood samples. None of the clinical risk factors were associated with plaque skewing. Plaque skewing was more often detected in plaques with a plaque hemorrhage (OR [95% CI]: 1.44 [1.06-1.98], P = 0.02). Moreover, skewed plaques were not associated with a higher incidence of composite and major events but were specifically associated with peripheral artery events during a 3-year follow-up period in a multivariate model (HR [95%CI]: 1.46 [1.09-1.97]; P = 0.007). CONCLUSIONS: XCI skewing is common in carotid plaques of females and is predictive for the occurrence of peripheral artery events within 3 years after carotid endarterectomy.

Sex-differences have been observed in the development of atherosclerosis between men and women. Women tend to have more stable and fibrous plaques compared to men. Sex-specific mechanisms such as mosaic loss of the Y chromosome in men, were associated with cardiovascular health. In women, despite X-linked mechanisms like X chromosome inactivation (XCI) skewing was identified in various tissues. However, its relationship with atherosclerosis has not yet been investigated. In our study, we explored if prevalence of XCI skewing in advanced atherosclerotic lesions related to cardiovascular risk factors, histological plaque data, and clinical information. We found that XCI skewing was present in approximately 50% of human plaques, particularly those with plaque hemorrhage. Interestingly, we did not find any notable relationship between plaque skewing and clinical risk factors. However, we found that XCI was more present in women with peripheral artery events during the 3 years period following carotid endarterectomy. In summary, our findings indicate that XCI skewing is commonly observed in carotid plaques among females and may serve as a predictive factor for the occurrence of peripheral artery events within 3 years after carotid endarterectomy.