Studies Of Atherosclerosis Research Articles

Profiling the L-arginine/arginase 1 metabolism in early and advanced atherosclerosis

Abstract Background Atherosclerosis is a chronic inflammatory disease and the primary underlying cause of cardiovascular disease (CVD). Recently, intracellular metabolic pathways have been identified as master switches of immune cell function and thus seem promising targets for therapeutic interventions aimed at lowering inflammation and thereby atherogenesis. Decades of research have demonstrated the importance of the amino acid (AA) L-arginine (Arg) in CVD. Although most research has focused on endothelium-dependent effects of Arg by the nitric oxide synthase (NOS), Arg metabolism - mainly through its metabolizing enzyme arginase 1 (Arg1) - has also been shown to regulate immune cell responses independent of its endothelial functions. Despite these findings, the cell-specific contribution of Arg/Arg1 metabolism on atherogenesis is still largely unknown. Purpose Profiling the Arg metabolism in endothelial and immune cells to identify cell-specific changes during athero-progression. Methods To investigate Arg metabolism in atherogenesis, we fed apolipoprotein E deficient (Apoe-­/­-) mice a Western diet (WD) for 6 and 12 weeks. Chow diet-fed aged-matched Apoe-­/-­ mice were used as littermate controls and C57BL/6 mice as steady-state controls. Systemic and local Arg concentrations were measured by mass-spectrometry. Arg metabolism in organs was studied by qPCR. Arg1 expression in atherosclerotic lesions was examined by immunohistochemistry (IHC). To assess cell-specific expression of Arg-related enzymes, aortic leukocytes from WD-fed Apoe-­/-­ mice were subjected to CITE-seq analysis. The role of T cell Arg1 was determined by nor-NOHA inhibition in Jurkat cells. Results AA measurements showed that systemic Arg was reduced in early and advanced atherogenesis (p<0.02), and splenic Arg was reduced in advanced atherogenesis (p=0.006) compared with steady state. In advanced atherosclerosis, Arg1 was decreased in the liver but increased in the spleen and aorta, whereas Nos2 was increased in the liver and aorta compared with steady state. To identify the cell types driving these local changes, we performed IHC on atherosclerotic lesions. Arg1+ lesional macrophages accumulated in advanced compared to early lesions (p=0.03), whereas Arg1+ endothelial cells tended to decrease (p=0.2). Surprisingly, we also found an accumulation of Arg1+ CD4+ T cells in lesions and a further upward trend with athero-progression. CITE-seq confirmed a constitutive expression of Arg1 in lymphoid clusters. In vitro experiments with Jurkat cells showed that arginase inhibition suppressed T cell proliferation and promoted apoptosis and migration (all p<0.0001). Conclusion Our data indicate that Arg metabolism is strongly regulated during athero-progression and suggest a so far unknown role of T cell-intrinsic Arg/Arg1 metabolism in the disease. Murine atherosclerosis studies are now being performed to decipher the cell-specific contribution of Arg/Arg1 metabolism in atherosclerosis.

Nutritional and potential health benefits of chufa oil, olive oil, and anhydrous milk fat against gallstone disease in a C57BL/6N mouse model.

Dietary lipids play a major role in many diseases, particularly cardiovascular diseases. Recently, the health value of plant oils, particularly heart health, has been recognized. Despite these facts, limited information is available on the potential nutritional and anti-arteriolosclerosis effects of chufa oil, olive oil, and anhydrous milk fat in C57BL/6N mice. In the present study, the effects of olive oil (OO), chufa oil (CO), and anhydrous milk fat (AMF) on 4-week-old C57BL/6N male mice, a model for studies of diet-induced atherosclerosis, were investigated. The AIN-93G-based diet was supplemented with 15% of either OO, CO, or AMF. The final mixture of the diets contained 15% fat, approximately 1.25% cholesterol, and 0.5% sodium cholate. The data obtained showed that most mice had gallstone disease. The highest percentage of the gallstones formed were found in AMF groups (approximately 85.7% of the mice). However, the lowest one was found in the chufa oil group (42.9%), followed by the olive oil group (57.1%). Although the mice's food intake significantly differed, their body weights did not change during the feeding period. The diet supplemented with CO resulted in a significant reduction in serum cholesterol compared with the other groups. Livers from the CO-fed group showed higher triglyceride levels than those from the AMF group. No significant differences were found in atherosclerotic lesions in the aortic valve between the groups. Collectively, our results show no deleterious nutritional effects of the fats used on C57BL/6N mice fed cholesterol-rich diets. Chufa oil improved cholesterol metabolism and atherogenic index in mice. However, the major issue is the formation of gallstones in all mice, which is most prominent in AMF, followed by olive oil and chufa oil diets.

Enhancement of high-density lipoprotein-associated protease inhibitor activity prevents atherosclerosis progression

Background and aimsInflammatory cells within atherosclerotic lesions secrete proteolytic enzymes that contribute to lesion progression and destabilization, increasing the risk for an acute cardiovascular event. Elastase is a serine protease, secreted by macrophages and neutrophils, that may contribute to the development of unstable plaque. We previously reported interaction of endogenous protease-inhibitor proteins with high-density lipoprotein (HDL), including alpha-1-antitrypsin, an inhibitor of elastase. These findings support a potential role for HDL as a modulator of protease activity. In this study, we test the hypothesis that enhancement of HDL-associated elastase inhibitor activity is protective against atherosclerotic lesion progression. MethodsWe designed an HDL-targeting protease inhibitor (HTPI) that binds to HDL and confers elastase inhibitor activity. Lipoprotein binding and the impact of HTPI on atherosclerosis were examined using mouse models. Histology and immunofluorescence staining of aortic root sections were used to examine the impact of HTPI on lesion morphology and inflammatory features. ResultsHTPI is a small (1.6 kDa) peptide with an elastase inhibitor domain, a soluble linker, and an HDL-targeting domain. When incubated with human plasma ex vivo, HTPI predominantly binds to HDL. Intravenous administration of HTPI to mice resulted in its binding to plasma HDL and increased elastase inhibitor activity on isolated HDL. Accumulation of HTPI within plaque was observed after administration to Apoe−/− mice. To examine the effect of HTPI treatment on atherosclerosis, prevention and progression studies were performed using Ldlr−/− mice fed Western diet. In both study designs, HTPI-treated mice had reduced lipid deposition in plaque. ConclusionsThese data support the hypothesis that HDL-associated anti-elastase activity can improve the atheroprotective potential of HDL and highlight the potential utility of HDL enrichment with anti-protease activity as an approach for stabilization of atherosclerotic lesions.

Unlocking the Potential of Pig Models in Atherosclerosis Research: Insights, Applications, and Future Directions

Background: Choosing an adequate model for studying human diseases, such as atherosclerosis, poses significant challenges. While small animals like mice and rats have been widely employed, the suitability of these models for specific research goals and objectives may vary. Furthermore, differences in lipid physiology and platelet quantities between rodents and humans can impact the translational relevance of findings. Large animal models, particularly swine, offer physiological similarities to humans and present a more accurate representation of clinical complications such as acute myocardial infarction and stroke. Objectives: This review aims to comprehensively evaluate the utility of the swine model in atherosclerosis research by examining the physiological and cardiovascular similarities between swine and humans. It also seeks to explore the significance of hyperlipidemia and atherosclerosis in pigs, considering both natural and genetically engineered mutant pig models. Additionally, the review aims to provide an overview of the potential applications of swine models in atherosclerosis regression research, thereby highlighting the advantages and limitations of employing swine in atherosclerosis studies. Conclusion: This review offers insights into the potential of the swine model as a valuable and versatile tool for expanding the horizons of atherosclerosis research, emphasizing the need for further exploration and utilization of large animal models in cardiovascular research.

Impact of immune system humanization on atherosclerosis in dyslipidemic immunocompromised mice

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Cariplo Foundation. PRIN (Italian Ministry of University and Research) Background and aim Given the key role of immune response during atherosclerosis and the therapeutic interest on biologics targeting human immune cells, the need of experimental models to translate molecular mechanisms and test therapeutic approaches for atherosclerosis is continuously increasing. Here we provide an immune and metabolic characterization of an innovative immunodeficient mouse humanized with human hematopoietic cells on an atheroprone background. Methods LDLR-KO mice were crossed with the immunodeficient C57BL/6J strain Rag2-KO/IL2rg-KO/CD47-KO (TKO, IMSR_JAX:025730) to generate an immunocompromised dyslipidemic mouse (TKO-LDLR KO mice) recipient of human hematopoietic stem cells (hCD34+). Results TKO-LDLR KO were first characterized for their immune and metabolic profile. TKO mice are deficient in mature lymphocytes and NK cells and this profile was conserved in TKO-LDLR KO mice. Under high cholesterol diet, TKO-LDLR KO present monocytosis with increased levels of Ly6Chi monocytes compared to TKO-LDLR KO at standard diet, develop marked dyslipidemia, steatosis and atherosclerosis. This profile confirms the suitability of TKO-LDLR KO mice for atherosclerosis studies. Next we tested the impact of immune system humanization on atherosclerosis. TKO-LDLR KO pups received a low-dose irradiation (200 cGy) and thereafter 2 x 10^5 hCD34+ were injected in the liver. Engraftment of human leukocytes (hCD45+) was evaluated after two months by flow cytometry analysis from tail blood. This approach allows to reconstitute between 10-30% of hCD45+, mainly B and T cells. The humanization with hCD34+ cells worsens atherosclerosis development as compared to non-humanized TKO-LDLR KO mice. Conclusion We have generated and characterized the humanized dyslipidemic TKO-LDLR KO mouse. This mouse model presents human B and T cells and represents and important toll to investigate the impact of human adaptive immune cell pharmacological modulation in the context of atherosclerosis.

Eliminate LDL cholesterol after heart attack … but only for a while.

There is a clear demonstration of the inverse linear correlation between LDL cholesterol levels and clinical benefit. However, the timing of the action of lipid-lowering drugs is not clear. According to animal studies with recombinant lipoprotein A-1, the composition of atherosclerosis changes within 40 h (with variations in lipid and inflammatory contents). Progression-regression studies of atherosclerosis in humans confirm the data, highlighting a rapid change in the plaque over 5 weeks. The data are also in line with what emerges from the survival curves of the old study comparing atorvastatin 80 mg vs. placebo (Myocardial Ischaemia Reduction with Aggressive Cholesterol Lowering). The spacing of the curves occurs after only 4 weeks, indicating the precociousness of the favourable effects of powerful statins. Finally, a recent Odyssey post hoc analysis compared the risk of cardiac death and coronary revascularization between a group in which alirocumab lowered LDL cholesterol to below 15 mg (Group 1 and in which the drug was therefore stopped) against the subjects in the placebo group (Group 2), applying a propensity score matching. The primary endpoint occurred in a lower percentage of patients in Group 1 (6.4 vs. 8.4%). Furthermore, patients in Group 1 had a significantly lower hazard ratio (HR) for major adverse cardiovascular events [0.72; 95% confidence interval (CI) 0.51-0.997; P = 0.047] compared with the entire alirocumab group vs. placebo (HR 0.85; 95% CI 0.78-0.93; P < 0.001). According to these preliminary observations, aggressive and early treatment of hypercholesterolaemia in subjects with acute coronary syndrome translates into improved clinical results compared with a strategy that provides for more gradual control. These data will need to be confirmed through further prospective clinical studies and ideally with early conducted atherosclerosis regression studies.

Cytokine Profiling of Plasma and Atherosclerotic Plaques in Patients Undergoing Carotid Endarterectomy.

Atherosclerotic plaques are sites of chronic inflammation with diverse cell contents and complex immune signaling. Plaque progression and destabilization are driven by the infiltration of immune cells and the cytokines that mediate their interactions. Here, we attempted to compare the systemic cytokine profiles in the blood plasma of patients with atherosclerosis and the local cytokine production, using ex vivo plaque explants from the same patients. The developed method of 41-plex xMAP data normalization allowed us to differentiate twenty-two cytokines produced by the plaque that were not readily detectable in free circulation and six cytokines elevated in blood plasma that may have other sources than atherosclerotic plaque. To verify the xMAP data on the putative atherogenesis-driving chemokines MCP-1 (CCL2), MIP-1α (CCL3), MIP-1β (CCL4), RANTES (CCL5), and fractalkine (CX3CL1), qPCR was performed. The MIP1A (CCL3), MIP1B (CCL4), FKN (CX3CL1), and MCP1 (CCL2) genes were expressed at high levels in the plaques, whereas RANTES (CCL5) was almost absent. The expression patterns of the chemokines were restricted to the plaque cell types: the MCP1 (CCL2) gene was predominantly expressed in endothelial cells and monocytes/macrophages, MIP1A (CCL3) in monocytes/macrophages, and MIP1B (CCL4) in monocytes/macrophages and T cells. RANTES (CCL5) was restricted to T cells, while FKN (CX3CL1) was not differentially expressed. Taken together, our data indicate a plaque-specific cytokine production profile that may be a useful tool in atherosclerosis studies.

Assessment of Subclinical Atherosclerosis in Asymptomatic People In Vivo: Measurements Suitable for Biomarker and Mendelian Randomization Studies.

One strategy to reduce the burden of cardiovascular disease is the early detection and treatment of atherosclerosis. This has led to significant interest in studies of subclinical atherosclerosis, using different phenotypes, not all of which are accurate reflections of the presence of asymptomatic atherosclerotic plaques. The aim of part 2 of this series is to provide a review of the existing literature on purported measures of subclinical disease and recommendations concerning which tests may be appropriate in the prevention of incident cardiovascular disease. We conducted a critical review of measurements used to infer the presence of subclinical atherosclerosis in the major conduit arteries and focused on the predictive value of these tests for future cardiovascular events, independent of conventional cardiovascular risk factors, in asymptomatic people. The emphasis was on studies with >10 000 person-years of follow-up, with meta-analysis of results reporting adjusted hazard ratios (HRs) with 95% CIs. The arterial territories were limited to carotid, coronary, aorta, and lower limb arteries. In the carotid arteries, the presence of plaque (8 studies) was independently associated with future stroke (pooled HR, 1.89 [1.04-3.44]) and cardiac events (7 studies), with a pooled HR, 1.77 (1.19-2.62). Increased coronary artery calcium (5 studies) was associated with the risk of coronary heart disease events, pooled HR, 1.54 (1.07-2.07) and increasing severity of calcification (by Agaston score) was associated with escalation of risk (13 studies). An ankle/brachial index (ABI) of <0.9, the pooled HR for cardiovascular death from 7 studies was 2.01 (1.43-2.81). There were insufficient studies of either, thoracic or aortic calcium, aortic diameter, or femoral plaque to synthesize the data based on consistent reporting of these measures. The presence of carotid plaque, coronary artery calcium, or abnormal ankle pressures seems to be a valid indicator of the presence of subclinical atherosclerosis and may be considered for use in biomarker, Mendelian randomization and similar studies.

Immune system humanization in dyslipidemic Rag2-KO/IL2rg-KO/CD47-KO/LDL-R KO mice controls atherosclerosis

Abstract Background and aim Given the key role of the immune response during atherosclerosis and the therapeutic interest of biologics targeting human immune cells, the need of experimental models to translate molecular mechanisms and to test therapeutic approaches for atherosclerosis is continuously increasing. Here we describe the characteristics of an innovative immunodeficient mouse humanized with hCD34+ cells on an atheroprone background. Methods LDLR-KO mice were crossed with the immunodeficient C57BL/6J strain Rag2-KO/IL2rg-KO/CD47-KO (TKO, IMSR_JAX:025730) to generate an immunocompromised dyslipidemic mouse recipient TKO-LDLR KO of human hematopoietic stem cells (hCD34+). Results TKO-LDLR KO were first characterized for their immune and metabolic profile. TKO mice are deficient in mature lymphocytes and NK cells and this profile was conserved in TKO-LDLR KO mice. Under high cholesterol diet for 8 weeks, both male and females TKO-LDLR KO present monocytosis with increased levels of Ly6Chi monocytes compared to TKO-LDLR KO at standard diet, develop marked dyslipidemia (total cholesterol 870.9 and 890.1 mg/dL male and females respectively), steatosis and atherosclerosis. This profile confirms the suitability of TKO-LDLR KO mice for atherosclerosis studies. Next we tested the impact of immune system humanization on atherosclerosis. TKO-LDLR KO pups received a low-dose irradiation (150-200 cGy) and thereafter 1,5-2 x 10^5 hCD34+ were injected with in the liver. Engraftment of human leukocytes (hCD45+) was evaluated after two months by flow cytometry analysis from tail blood. This approach allows to reconstitute between 10-30% of hCD45+, mainly B and T cells. The humanization with hCD34+ cells affected atherosclerosis development as compared to non-humanized TKO-LDLR KO mice. Conclusion We have generated and characterized for the first time a humanized dyslipidemic TKO-LDLR KO mice. This mouse model presents human B and T cells and represent and important toll to investigate the impact of biologics targeted toward human targets in the context of atherosclerosis.

Abstract 14843: Unveiling the Phenotype of Smooth Muscle Foam Cells in Human Atherosclerotic Lesions: Insights From Bulk and Single Cell RNA Sequencing

Background and Aims: Our previous studies of human coronary atherosclerosis and ApoE-/- mice indicated that at least 50% and ~70% of foam cells are of smooth muscle cell (SMC) origin, respectively. We also found that SMCs generate a distinct class of foam cells, due to several gene expression and regulatory differences compared to macrophage foam cells. In the current investigation we utilized transcriptomic approaches to identify and characterize the phenotype of SMC foam cells of human coronary plaques and in SMCs treated with aggregated LDL (ag-LDL). Methods: Sections of fresh human coronary artery were subjected to gentle digestion and the isolated cells used for single-cell RNA Sequencing (scRNA-Seq) (n=3) using 10X Genomics Chromium Single Cell 3’ Reagent Kits v3 Technology. Human vascular SMCs were treated with 100 μg/mL ag-LDL for 24 h (n=3) and stained with the fluorescent lipid probe BODIPY493/503. BODIPY high SMCs were collected and subjected to bulk RNA sequencing along with non-treated SMCs as control. Results: Single cell RNA sequencing of cells isolated from human coronary arteries followed by unsupervised Seurat-based clustering (R version 4.2.0) identified 15 distinct clusters including 8 SMC clusters with varying degrees of differentiation and macrophage foam and non-foam cells. The top 70 upregulated genes in ag-LDL treated SMCs were used to identify clusters corresponding to SMC foam cells in the scRNA-seq dataset. We found that these genes are mostly enriched in 2 clusters of less differentiated SMCs. SMC and macrophage foam cell clusters display distinct characteristics. SMC foam cell clusters exhibit upregulation of complement and coagulation cascades, as well as ECM-receptor interaction genes. In contrast, the macrophage foam cell cluster shows enrichment of proinflammatory genes, genes involved in the response to unfolded protein, and both pro- and anti-apoptotic genes. Conclusion: Our studies provide novel tools to investigate the nature of SMC foam cells in human atherosclerosis and may provide unique markers for SMC foam cells. Gaining a comprehensive insight of the significance and characteristics of SMC foam cells is crucial in elucidating their ultimate role and potential as a therapeutic target in atherosclerosis.

Abstract 12706: The Impact of Social Determinants of Health and Lifestyle Factors on the Association of Lipoprotein(a) With Cardiovascular Outcomes in Two US Cohorts

Introduction: In European cohorts, a higher Mediterranean diet or Life’s Simple 7 (LS7) score abolished or attenuated the risk associated with increasing Lipoprotein(a) [Lp(a)] on cardiovascular (CV) outcomes. This is unstudied in US cohorts. Further, the impact of social determinants of health (SDOH) on the association of Lp(a) with CV outcomes is unstudied. Hypothesis: We hypothesized that SDOH and LS7 scores would attenuate the association of Lp(a) with CV outcomes in US cohorts. Methods: We used data from the Atherosclerosis Risk in Communities (ARIC) and the Multi-Ethnic Study of Atherosclerosis (MESA) studies. Outcomes were time until first fatal or nonfatal myocardial infarction (MI) or stroke. We performed multivariable cox proportional hazard analyses with covariates of age, gender, race and ethnicity, SDOH score, and LS7 score. We identified five SDOH in ARIC and 11 in MESA. The Lp(a) protein-mass from ARIC was tripled to be similar to the Lp(a) total-mass measurement in MESA. Results: ARIC included 15,072 individuals (median Lp(a) = 17.3 mg/dL (IQR 7.5, 40.6)) with 16.2 years average follow up. MESA included 6,822 individuals (Median Lp(a) = 18.3 (IQR 6.9, 43.8)) with 12.3 year average follow up. In age, gender, and race and ethnicity adjusted analyses Lp(a) was associated with MI in ARIC (HR 1.10, p&lt;0.001) and MESA (HR 1.09, p&lt;0.001). Lp(a) was also associated with stroke in ARIC (HR 1.08, p&lt;0.001) but not MESA (HR 0.97, p=0.50). With SDOH and LS7 added to the model, association of Lp(a) with CV outcomes remained similar in ARIC and MESA. SDOH correlated positively and LS7 correlated negatively with MI and stroke. In MESA there was an interaction between LS7 score and Lp(a) for MI. Conclusions: Lp(a) remained similarly associated with CV outcomes in US cohorts after accounting for social and lifestyle factors, although LS7 score may have a small modifying effect on the association between Lp(a) and MI. SDOH and LS7 are strong predictors for CV outcomes.

Abstract 17384: Unraveling the Impact of VAMP-8 Deficiency on Atherogenesis: A Fresh Perspective on Platelet Involvement

Introduction and Objective: Recognized for their intricate role in atherogenesis, platelets interact with oxidized low-density lipoprotein (oxLDL), immune cells, and endothelial cells and release granule proteins and microparticles, contributing to the onset and advancement of atherosclerosis. Despite the challenges of antiplatelet treatment in primary prevention, exploring alternative platelet targets could provide key insights into their role in atherogenesis. This study pivots on the soluble N-ethylmaleimide-sensitive factor activating protein receptor (SNARE) proteins, notably vesicle associated membrane protein 8 (VAMP-8) - the primary vesicle membrane (v-SNARE) and vital facilitator of platelet secretion. Approach and Results: The profound impairment in α-granule, dense granule, and lysosome release due to VAMP-8 deficiency directed our investigation towards its potential role in atherogenesis. Using RNA-seq data from washed platelets of VAMP-8-/- mice versus wildtypes, we first analyzed the molecular signature of VAMP-8 deficiency. Gene ontology analysis revealed that the major differences in enriched genes between the two groups involved triglyceride biosynthetic process and platelet calcium homeostasis. We initiated atherosclerosis studies using ApoE -/- mice crossed with VAMP-8 -/- mice (n=11) alongside littermate controls (n=9), all fed a high cholesterol diet for 15 weeks. Remarkably, the deletion of VAMP-8 led to a substantial reduction in atherosclerotic lesion development when compared to the control group. Notably, this phenotype manifested irrespective of total cholesterol levels, as plasma cholesterol remained consistent across all groups. Conclusion: Our findings reveal that VAMP8 deficiency markedly mitigates atherogenesis, thereby proposing a novel perspective to explore the influence of platelet cargo secretion on the inception of atherosclerosis. We are currently conducting additional studies to uncover the underlying mechanisms responsible for these observations

The Role of the Circadian Rhythm in Dyslipidaemia and Vascular Inflammation Leading to Atherosclerosis.

Cardiovascular diseases (CVD) are among the leading causes of death worldwide. Many lines of evidence suggest that the disturbances in circadian rhythm are responsible for the development of CVDs; however, circadian misalignment is not yet a treatable trait in clinical practice. The circadian rhythm is controlled by the central clock located in the suprachiasmatic nucleus and clock genes (molecular clock) located in all cells. Dyslipidaemia and vascular inflammation are two hallmarks of atherosclerosis and numerous experimental studies conclude that they are under direct influence by both central and molecular clocks. This review will summarise the results of experimental studies on lipid metabolism, vascular inflammation and circadian rhythm, and translate them into the pathophysiology of atherosclerosis and cardiovascular disease. We discuss the effect of time-respected administration of medications in cardiovascular medicine. We review the evidence on the effect of bright light and melatonin on cardiovascular health, lipid metabolism and vascular inflammation. Finally, we suggest an agenda for future research and recommend on clinical practice.

Abstract 023: Prior Sflt1 Induced Preeclampsia Exacerbates Post-partum Hypertension-mediated Aortic Stiffness And Hypercholesterolemia-induced Atherosclerotic Inflammation

Preeclampsia (PE) is new high blood pressure (BP) and organ damage occurring late in pregnancy in association with increased soluble VEGF receptor (sFlt1). PE survivors have increased risk of future hypertension and myocardial infarction/stroke. We hypothesized that exposure to high sFlt1 during pregnancy exacerbates hypertension and atherosclerosis post-partum. PE was induced by transient adenoviral expression of sFlt1 compared to control virus in pregnant mice. PE mice had elevated sFlt1, BP and kidney damage during pregnancy which resolve post partum. Two months post-partum, prior PE mice had significantly increased BP response to high salt diet. After high BP stimuli, we studied large and small artery function. Prior PE mice had diminished nitric oxide-mediated vasodilation and stiffer aortas with more fibrosis as measured by pulse wave velocity (Con:3.7 vs sFlt:5.9 mm/ms, p&lt;0.0001) and trichrome staining (Con:13.7% vs sFlt:33.9%, p=0.0009). Atherosclerosis studies exposed LDLR knockout mice to PE followed by high fat diet feeding for 8 weeks. Body weight, fasting glucose and cholesterol were not altered by prior PE. Aortic roots were histologically analyzed for plaque size and composition. Aortic root plaque size (Con:73.3 vs sFlt:78.0 AU, p=0.60) and necrotic core were not different between groups. Aortic arch plaque inflammation was quantified via flow cytometry showing significantly increased plaque CD45+ leukocytes (sFlt:1.6 fold, p=0.036) and T cells (sFlt:1.8 fold, p=0.031) from mice with prior PE. Atheroprone mice with prior PE had significantly increased aortic expression of CCL22 (sFlt:1.5 fold, p=0.047), providing a potential mechanism for increased T cell infiltration into atherosclerotic plaques. Experimental PE produces a state of enhanced sensitivity to hypertensive stimuli and increased vascular inflammation in atherosclerotic plaques supporting the concept that PE directly exacerbates hypertension, vascular stiffness, and atherosclerotic inflammation independent of pre-existing risk factors.

Association of Intima-Media Thickness Measured at the Common Carotid Artery With Incident Carotid Plaque: Individual Participant Data Meta-Analysis of 20 Prospective Studies.

Background The association between common carotid artery intima-media thickness (CCA-IMT) and incident carotid plaque has not been characterized fully. We therefore aimed to precisely quantify the relationship between CCA-IMT and carotid plaque development. Methods and Results We undertook an individual participant data meta-analysis of 20 prospective studies from the Proof-ATHERO (Prospective Studies of Atherosclerosis) consortium that recorded baseline CCA-IMT and incident carotid plaque involving 21 494 individuals without a history of cardiovascular disease and without preexisting carotid plaque at baseline. Mean baseline age was 56 years (SD, 9 years), 55% were women, and mean baseline CCA-IMT was 0.71 mm (SD, 0.17 mm). Over a median follow-up of 5.9 years (5th-95th percentile, 1.9-19.0 years), 8278 individuals developed first-ever carotid plaque. We combined study-specific odds ratios (ORs) for incident carotid plaque using random-effects meta-analysis. Baseline CCA-IMT was approximately log-linearly associated with the odds of developing carotid plaque. The age-, sex-, and trial arm-adjusted OR for carotid plaque per SD higher baseline CCA-IMT was 1.40 (95% CI, 1.31-1.50; I2=63.9%). The corresponding OR that was further adjusted for ethnicity, smoking, diabetes, body mass index, systolic blood pressure, low- and high-density lipoprotein cholesterol, and lipid-lowering and antihypertensive medication was 1.34 (95% CI, 1.24-1.45; I2=59.4%; 14 studies; 16 297 participants; 6381 incident plaques). We observed no significant effect modification across clinically relevant subgroups. Sensitivity analysis restricted to studies defining plaque as focal thickening yielded a comparable OR (1.38 [95% CI, 1.29-1.47]; I2=57.1%; 14 studies; 17 352 participants; 6991 incident plaques). Conclusions Our large-scale individual participant data meta-analysis demonstrated that CCA-IMT is associated with the long-term risk of developing first-ever carotid plaque, independent of traditional cardiovascular risk factors.

Abstract 166: Memory Cd8 T Cells Contribute To Atherosclerosis In Aged Mice

Aging is a strong risk factor for atherosclerosis and aging significantly impacts immune cell populations and function. Immune cells are a major contributor to development of atherosclerosis; however, most preclinical atherosclerosis studies are performed in young mice. The role of aging on CD8 + T cells during atherogenesis remains unclear. Here we determined that depletion of CD8 + T cells attenuated atherogenesis in aged, but not young, mice. Furthermore, adoptive transfer of splenic CD8 + T cells from aged mice which contain a high proportion of memory T cells significantly enhanced atherosclerosis in young Cd8 -/- recipient mice compared with transfer of CD8 + T cells from young donor mice. Finally, we characterized T cells in healthy and atherosclerotic young and aged mice by single-cell RNA-sequencing (scRNAseq) and T cell receptor sequencing (TCR-seq). We found that with aging effector memory, central memory, and granzyme K + effector memory CD8 + T cells accumulate within atherosclerotic plaques, and aging induces transcriptomic changes related to CD8 + T cell activation, migration, cytotoxicity, and exhaustion. Overall, our study identifies memory CD8 + T cells as potential therapeutic targets for reducing atherosclerosis in older adults.

Abstract 708: Murine Atherosclerosis Data Integration: The Sum Is Greater Than The Parts

Translation of murine atherosclerosis studies to human disease has limited reproducibility. Our prior work showed that aggregated data from one mouse atherosclerosis model identified etiologic pathways and networks associated with human atherosclerotic cardiovascular disease (ASCVD). Therefore, we extracted data from 991 ApoE knockout (KO) manuscripts and 544 LDLR KO manuscripts to identify 405 unique genes associated with significant changes in plaque size in mice. The impact of each gene on plaque size was analyzed using Ingenuity Pathway Analysis to contextualize the gene data. The most significantly activated pathways for genes that increased plaque size were neuroinflammation (p=3.02 E-55) and hepatic fibrosis signaling (p=2.25 E-52), while the LXR/RXR pathway was the most significantly downregulated (p=1.32 E-37). We then performed association analyses from Vanderbilt University Medical Center’s BioVU using genetically predicted gene expression of the individual genes from these datasets. Neither the aggregated genes identified in each individual mouse model nor the genes directly studied in the murine models that mapped to the top pathways were significantly enriched for association with ASCVD in humans. However, when homologous human gene sets derived from the top identified murine pathways were considered as a whole, they were highly significantly enriched for association with ASCVD (Fig 1). Further, this method identified human genes significantly associated with ASCVD that were not directly studied in mice. For example, in the neuroinflammation pathway, the genes studied in mice were not enriched for ASCVD, yet 61/117 genes (52%) in the global pathway were associated with ASCVD (p=0.00017), 43 of which were not directly studied in mice. Thus, integration of murine data identifies novel pathways significantly associated with human ASCVD thereby providing mechanistic insight into human disease only possible through contextualization.

Impact of immune system humanization on atherosclerosis in dyslipidemic Rag2-KO/IL2rg-KO/CD47-KO/LDL-R KO mice

Aim: Given the key role of the immune response during atherosclerosis and the therapeutic interest of biologics targeting human immune cells, the need of experimental models to translate molecular mechanisms and to test therapeutic approaches for atherosclerosis is continuously increasing. Here we describe the characteristics of an innovative immunodeficient mouse humanized with hCD34+ cells on an atheroprone background. Methods: LDLR-KO mice were crossed with the immunodeficient C57BL/6J strain Rag2-KO/IL2rg-KO/CD47-KO (TKO, IMSR_JAX:025730) to generate an immunocompromised dyslipidemic mouse TKO-LDLR KO recipient of human hematopoietic stem cells (hCD34+). Results: TKO-LDLR KO were first characterized for their immune and metabolic profile. TKO mice are deficient in mature lymphocytes and NK cells and this profile was conserved in TKO-LDLR KO mice. Under high cholesterol diet for 8 weeks, both males and females TKO-LDLR KO present monocytosis with increased levels of Ly6Chi monocytes compared to TKO-LDLR KO at standard diet, develop marked dyslipidemia (total cholesterol 870.9 and 890.1 mg/dL male and females respectively), steatosis and atherosclerosis. This profile confirms the suitability of TKO-LDLR KO mice for atherosclerosis studies. Next, we tested the impact of immune system humanization. TKO-LDLR KO pups received a low-dose irradiation (150-200 cGy) and thereafter 1,5-2 x 10^5 hCD34+ were injected with in the liver. Engraftment of human leukocytes (hCD45+) was evaluated after two months by flow cytometry analysis from tail blood. This approach allows to reconstitute between 10-30% of hCD45+, mainly B and T cells. Conclusions: We have generated and characterized for the first time a humanized dyslipidemic TKO-LDLR KO mouse. This mouse model presents human B and T cells and could represent an important tool to investigate the impact of biologics targeted toward human targets in the context of atherosclerosis.

MicroRNA detection in carotid atherosclerosis: prospects for clinical use

Carotid atherosclerosis is a significant cause of cerebrovascular disease. However, with many candidate markers, precise assessment of its development and progression risks is still limited. This paper reviews state-of-the-art concepts of microRNA as an atherogenesis biomarker throughout various stages including endothelial dysfunction, cholesterol/lipid metabolism, inflammation, oxidative stress, angiogenesis regulation, and proliferation and migration of vascular smooth muscle cells. Based on the available literature, we have described most significant microRNAs for each stage characterized in brief. We have visualized interactions between microRNAs and validated target genes with MIENTURNET and suggest and justify a set of microRNAs for further pilot studies of carotid atherosclerosis.

A Transcriptional Regulation Bioinformatics Pipeline to Predict Co‐Regulated Genes in Vascular Smooth Muscle Cell Phenotypic Transitions During Atherosclerosis

The rupture of vulnerable or advanced atherosclerotic lesions contributes to myocardial infarctions and strokes, the leading causes of death globally. During all stages of atherosclerosis, vascular smooth muscle cells (VSMCs) are recruited as a major source of plaque cells within lesions, where they undergo phenotypic modulation and give rise to both plaque‐stabilizing and destabilizing phenotypes. Because most atherosclerosis studies test the functional role of single transcription factors, genes, and proteins in VSMCs, many aspects of how VSMC plasticity can be clinically exploited to prevent the rupture of vulnerable atherosclerotic lesions remain unclear. Systems biology approaches have emerged as a promising avenue for characterizing cellular dynamics at the organismal level, but they remain under‐utilized in the field of cardiovascular medicine. This study proposes a novel systems biology pipeline that integrates experimental and computational tools with large datasets measuring the transcriptomes and epigenomes of phenotypically transitioning VSMCs. Our pipeline allows users to identify candidate transcription factors that co‐regulate mouse or human gene sets controlling specific VSMC phenotypic transitions during atherosclerosis. The computational algorithms developed in this workflow integrate an array of publicly available databases, such as the Ensembl genome database and the JASPAR transcription factor database. To demonstrate the translational potential of our pipeline, we used it to test the hypothesis that the murine mesenchymal marker stem cell antigen‐1 Sca1(Ly6a) has a human ortholog, which has not been previously validated as a target in clinical therapies. To test the hypothesis that there are sets of genes co‐regulated with Ly6ain human VSMCs which, when expressed in concert, promote a distinct phenotypic state marked by Ly6ain mice, we integrated genomic and ATAC‐seq analyses of VSMCs to identify murine genes with human orthologs that bind Ly6a‐specific transcription factors. Specifically, we predict that the transcription factors ETS1, KLF5, GATA6, and SOX10 co‐regulate sets of human genes with Ly6a. While prior studies have associated these transcription factors with VSMC proliferation and phenotypic modulation, we specifically predict these Ly6a‐specific transcription factor co‐regulate the following human gene sets: PHACTR1, EFHC1, LAMC2(ETS1); TTC33, RUNX1, KIAA1217(KLF5); TMEM50A(GATA6); and ZBTB20, MYLK2(SOX10). To validate these predictions, we will determine if these transcription factors and their co‐regulated genes are expressed in single cell RNA‐sequencing analyses of human carotid arteries and can be detected with immunofluorescence staining of human coronary artery sections. We will also use siRNA to target these candidate transcription factors and genes in cultured VSMCs. The results of our pipeline will help identify novel transcriptional regulatory networks in VSMCs that can be therapeutically targeted for the treatment of advanced atherosclerosis.