Flow Perturbation Mediates Neutrophil Recruitment and Potentiates Endothelial Injury via TLR2 in Mice: Implications for Superficial Erosion

The clonal hematopoiesis mutation Jak2V617F aggravates endothelial injury and thrombosis in arteries with erosion-like intimas

BACKGROUND

Superficial plaque erosion causes many acute coronary syndromes. However, mechanisms of plaque erosion remain poorly understood, and we lack directed therapeutics for thrombotic complication. Human eroded plaques can harbor neutrophil extracellular traps (NETs) that propagate endothelial damage at experimental arterial lesions that recapitulate superficial erosion. Clonal Hematopoiesis of Indeterminate Potential (CHIP) denotes age-related clonal expansion of bone marrow-derived cells harboring somatic mutations in the absence of overt hematological disease. CHIP heightens the risk of cardiovascular disease, with the greatest increase seen in individuals with JAK2V617F. Neutrophils from mice and humans with JAK2V617F undergo NETosis more readily than Jak2WT (wild-type) cells. We hypothesized that JAK2V617F, by increasing propensity to NETosis, exacerbates aspects of superficial erosion.

METHODS AND RESULTS

We generated Jak2V617F and Jak2WT mice with heterozygous Jak2V617F in myeloid cells. We induced areas of denuded endothelium that recapitulate features of superficial erosion and assessed endothelial integrity, cellular composition of the erosion, thrombosis rates, and response to ruxolitinib, a clinically available JAK1/2 inhibitor, in relation to genotype. Following experimental erosion, Jak2V617F mice have greater impairment of endothelial barrier function and increased rates of arterial thrombosis. Neointimas in Jak2V617F mice exhibit increased apoptosis, NETosis, and platelet recruitment. Jak2V617F mice treated with ruxolitinib show increased endothelial continuity and reduced apoptosis in the neointima comparable to levels in Jak2WT.

CONCLUSIONS

These observations provide new mechanistic insight into the pathophysiology of superficial erosion, the heightened risk for myocardial infarction in JAK2V617F CHIP, and point the way to personalized therapeutics based on CHIP status.

Autoimmune diseases and atherosclerotic cardiovascular disease

Autoimmune diseases are associated with a dramatically increased risk of atherosclerotic cardiovascular disease and its clinical manifestations. The increased risk is consistent with the notion that atherogenesis is modulated by both protective and disease-promoting immune mechanisms. Notably, traditional cardiovascular risk factors such as dyslipidaemia and hypertension alone do not explain the increased risk of cardiovascular disease associated with autoimmune diseases. Several mechanisms have been implicated in mediating the autoimmunity-associated cardiovascular risk, either directly or by modulating the effect of other risk factors in a complex interplay. Aberrant leukocyte function and pro-inflammatory cytokines are central to both disease entities, resulting in vascular dysfunction, impaired resolution of inflammation and promotion of chronic inflammation. Similarly, loss of tolerance to self-antigens and the generation of autoantibodies are key features of autoimmunity but are also implicated in the maladaptive inflammatory response during atherosclerotic cardiovascular disease. Therefore, immunomodulatory therapies are potential efficacious interventions to directly reduce the risk of cardiovascular disease, and biomarkers of autoimmune disease activity could be relevant tools to stratify patients with autoimmunity according to their cardiovascular risk. In this Review, we discuss the pathophysiological aspects of the increased cardiovascular risk associated with autoimmunity and highlight the many open questions that need to be answered to develop novel therapies that specifically address this unmet clinical need.

Atherosclerotic Autoantigen ALDH4A1 as a Novel Immunological Indicator for Plaque Erosion in Patients with ST Segment Elevated Myocardial Infarction

OBJECTIVE

 Aldehyde dehydrogenase 4A1 (ALDH4A1) was recently reported to be a novel autoantigen of atherosclerosis. However, its role in different phenotypes of acute coronary syndrome remains unclear. Herein, we planned to explore the circulating and regional expression of ALDH4A1 in patients with plaque rupture (PR) and plaque erosion (PE) determined by optical coherence tomography (OCT).

METHODS AND RESULTS

 After applying the inclusion and exclusion criteria, a prospective series of 312 patients with ST segment elevated myocardial infarction (STEMI), including 161 patients with PR and 151 patients with PE determined by OCT, were enrolled for plasma ALDH4A1 testing. In addition, ALDH4A1 was quantified using immunofluorescence in aspirated coronary thrombus samples obtained from 31 patients with PR and 25 patients with PE. In addition, we established an atherosclerosis mouse model and analyzed the distribution of ALDH4A1 expression in different mouse organs. Furthermore, we compared the level of ALDH4A1 in the spleen and carotid artery between Apoe-/- and C57 mice. The results showed that the plasma level of ALDH4A1 was significantly higher in STEMI patients with PE than in those with PR (4.6 ng/mL [2.2-8.7] vs. 3.5 ng/mL [1.6-5.6] p = 0.005). The expression of ALDH4A1 in aspirated coronary thrombi was also significantly higher in patients with PE than in those with PR (mean gray value: 32.0 [23.6-40.6] vs. 16.8 [14.0-24.5], p < 0.001). In animal models, the expression of ALDH4A1 is much higher in the spleen than in other organs, and the level of ALDH4A1 is significantly elevated in the spleen and carotid artery of Apoe-/- mice compared with C57 mice.

CONCLUSION

 The high levels of ALDH4A1 in the plasma and aspirated coronary thrombi independently correlated with PE in patients with STEMI. These results suggested that ALDH4A1 is involved in the mechanism of PE and serves as a promising biomarker and treatment target for patients with PE.

Elevated plasma levels of factor VIII enhance arterial thrombus formation on erosive smooth muscle cell-rich neointima but not normal intima in rabbits

BACKGROUND

Plaque erosion, a type of coronary atherothrombosis, involves superficial injury to smooth muscle cell (SMC)-rich plaques. Elevated levels of coagulation factor VIII (FVIII) correlate with an increased ischemic heart disease risk. FVIII may contribute to thrombus formation on eroded plaques.

AIMS

We aimed to elucidate the role of elevated FVIII in arterial thrombus formation within SMC-rich neointima in rabbits.

METHODS AND RESULTS

We assessed the effect of recombinant human FVIII (rFVIII) on blood coagulation in vitro and platelet aggregation ex vivo. An SMC-rich neointima was induced through balloon injury to the unilateral femoral artery. Three weeks after the first balloon injury, superficial erosive injury and thrombus formation were initiated with a second balloon injury of the bilateral femoral arteries 45 min after the administration of rFVIII (100 IU/kg) or saline. The thrombus area and contents were histologically measured 15 min after the second balloon injury. rFVIII administration reduced the activated partial thromboplastin time and augmented botrocetin-induced, but not collagen- or adenosine 5'-diphosphate-induced, platelet aggregation. While rFVIII did not influence platelet-thrombus formation in normal intima, it increased thrombus formation on SMC-rich neointima post-superficial erosive injury. Enhanced immunopositivity for glycoprotein IIb/IIIa and fibrin was observed in rFVIII-administered SMC-rich neointima. Neutrophil count in the arterial thrombus on the SMC-rich neointima correlated positively with thrombus size in the control group, unlike the rFVIII group.

CONCLUSIONS

Increased FVIII contributes to thrombus propagation within erosive SMC-rich neointima, highlighting FVIII's potential role in plaque erosion-related atherothrombosis.

Neutrophil Extracellular Traps in Cardiovascular and Aortic Disease: A Narrative Review on Molecular Mechanisms and Therapeutic Targeting

Neutrophil extracellular traps (NETs), composed of DNA, histones, and antimicrobial proteins, are released by neutrophils in response to pathogens but are also recognized for their involvement in a range of pathological processes, including autoimmune diseases, cancer, and cardiovascular diseases. This review explores the intricate roles of NETs in different cardiovascular conditions such as thrombosis, atherosclerosis, myocardial infarction, COVID-19, and particularly in the pathogenesis of abdominal aortic aneurysms. We elucidate the mechanisms underlying NET formation and function, provide a foundational understanding of their biological significance, and highlight the contribution of NETs to inflammation, thrombosis, and tissue remodeling in vascular disease. Therapeutic strategies for preventing NET release are compared with approaches targeting components of formed NETs in cardiovascular disease. Current limitations and potential avenues for clinical translation of anti-NET treatments are discussed.

Identification of important genes related to anoikis in acute myocardial infarction

Acute myocardial infarction (AMI) increasingly precipitates severe heart failure, with diagnoses now extending to progressively younger demographics. The focus of this study was to pinpoint critical genes linked to both AMI and anoikis, thereby unveiling potential novel biomarkers for AMI detection and intervention. Differential analysis was performed to identify significant differences in expression, and gene functionality was explored. Weighted gene coexpression network analysis (WGCNA) was used to construct gene coexpression networks. Immunoinfiltration analysis quantified immune cell abundance. Protein-protein interaction (PPI) analysis identified the proteins that interact with theanoikis. MCODE identified key functional modules. Drug enrichment analysis identified relevant compounds explored in the DsigDB. Through WGCNA, 13 key genes associated with anoikis and differentially expressed genes were identified. GO and KEGG pathway enrichment revealed the regulation of apoptotic signalling pathways and negative regulation of anoikis. PPI network analysis was also conducted, and 10 hub genes, such as IL1B, ZAP70, LCK, FASLG, CD4, LRP1, CDH2, MERTK, APOE and VTN were identified. IL1B were correlated with macrophages, mast cells, neutrophils and Tcells in MI, and the most common predicted medications were roxithromycin, NSC267099 and alsterpaullone. This study identified key genes associated with AMI and anoikis, highlighting their role in immune infiltration, diagnosis and medication prediction. These findings provide valuable insights into potential biomarkers and therapeutic targets for AMI.

"How to Release or Not Release, That Is the Question." A Review of Interleukin-1 Cellular Release Mechanisms in Vascular Inflammation

Cardiovascular disease remains the leading cause of death worldwide, characterized by atherosclerotic activity within large and medium-sized arteries. Inflammation has been shown to be a primary driver of atherosclerotic plaque formation, with interleukin-1 (IL-1) having a principal role. This review focuses on the current state of knowledge of molecular mechanisms of IL-1 release from cells in atherosclerotic plaques. A more in-depth understanding of the process of IL-1's release into the vascular environment is necessary for the treatment of inflammatory disease processes, as the current selection of medicines being used primarily target IL-1 after it has been released. IL-1 is secreted by several heterogenous mechanisms, some of which are cell type-specific and could provide further specialized targets for therapeutic intervention. A major unmet challenge is to understand the mechanism before and leading to IL-1 release, especially by cells in atherosclerotic plaques, including endothelial cells, vascular smooth muscle cells, and macrophages. Data so far indicate a heterogeneity of IL-1 release mechanisms that vary according to cell type and are stimulus-dependent. Unraveling this complexity may reveal new targets to block excess vascular inflammation.

Phenotypic alteration by dengue virus serotype 2 delays neutrophil apoptosis and stimulates the release of prosurvival secretome with immunomodulatory functions

Neutrophils are the most abundant granuloytes, are phenotypically heterogeneous, and exert detrimental or protective roles during antiviral response. Dengue virus has been reported to activate neutrophils. However, the effect of the dengue virus on the neutrophil phenotypes, survival, and release of inflammatory secretome is yet to be understood. Herein, we investigated the effect of dengue virus serotype 2 (DV-2) on effector functions of naïve neutrophils and studied the impact of its secretome on different immune cells. We found that DV-2 activates purified human neutrophils and causes a significant shift toward the CD16bright/CD62Ldim subtype in a multiplicity of infection and time-dependent manner. These phenotypically altered neutrophils show delayed apoptosis through nuclear factor κB and PI3K pathways and have decreased phagocytic capacity. Treatment of neutrophils with myeloperoxidase and PAD4 inhibitor before DV-2 incubation significantly reduced DV-2-induced double-stranded DNA release, suggesting that myeloperoxidase and PAD4 were involved at early stages for the neutrophil activation and double-stranded DNA release. We also report that DV-2-stimulated neutrophil secretome had a significant effect on viral infection, platelet activation, and naïve neutrophil survival via binding of tumor necrosis factor α to tumor necrosis factor receptor 1/2 receptors. Furthermore, incubation of endothelial cells with the DV-2-stimulated neutrophil secretome potentially inhibits proliferation and wound healing capacity and induces endothelial cell death, which can contribute to endothelial barrier dysfunction. In conclusion, the neutrophil-DV-2 interaction modulates the phenotype of neutrophils and the release of prosurvival and antiviral secretome that may act as a double-edged sword during dengue pathogenesis.

Lipid Content Distribution and its Clinical Implication in Patients with Acute Myocardial Infarction-Plaque Erosion: Results from the Prospective OCTAMI Study

AIMS

Plaque erosion (PE) is one of the main plaque phenotypes of acute coronary syndrome (ACS). However, the underlying plaque component and distribution have not been systematically analysed. This study aims to investigate the distribution of lipid and calcium content in culprit lesions assessed by optical coherence tomography (OCT) in patients with PE and explore its relationship with prognosis in a cohort of ST segment elevation myocardial infarction (STEMI) patients.

METHODS

A prospective cohort of 576 patients with STEMI was enrolled in our study. After exclusion, 152 PE patients with clear underlying plaque components were ultimately analysed. The culprit lesion was divided into the border zone, external erosion zone and erosion site in the longitudinal view. Each pullback of the culprit lesions was assessed by 3 independent investigators frame-by-frame, and the quantity and distribution of lipid and calcium components were recorded.

RESULTS

Of the 152 PE patients, lipid and calcium contents were more likely to exist in the external erosion zone than in the other regions. In particular, a high level of lipid content proximal to the erosion site was significantly associated with plaque vulnerability and a higher incidence of MACEs.

CONCLUSION

This study revealed that high level of lipid content in the proximal external erosion zone was related to high-risk plaque characteristics and poor prognosis, which provided a novel method for risk stratification and precise management in patients with plaque erosion.

Unraveling the Role of Sex in Endothelial Cell Dysfunction: Evidence From Lineage Tracing Mice and Cultured Cells

BACKGROUND

Biological sex differences play a vital role in cardiovascular diseases, including atherosclerosis. The endothelium is a critical contributor to cardiovascular pathologies since endothelial cells (ECs) regulate vascular tone, redox balance, and inflammatory reactions. Although EC activation and dysfunction play an essential role in the early and late stages of atherosclerosis development, little is known about sex-dependent differences in EC.

METHODS

We used human and mouse aortic EC as well as EC-lineage tracing (Cdh5-CreERT2 Rosa-YFP [yellow fluorescence protein]) atherosclerotic Apoe-/- mice to investigate the biological sexual dimorphism of the EC functions in vitro and in vivo. Bioinformatics analyses were performed on male and female mouse aortic EC and human lung and aortic EC.

RESULTS

In vitro, female human and mouse aortic ECs showed more apoptosis and higher cellular reactive oxygen species levels than male EC. In addition, female mouse aortic EC had lower mitochondrial membrane potential (ΔΨm), lower TFAM (mitochondrial transcription factor A) levels, and decreased angiogenic potential (tube formation, cell viability, and proliferation) compared with male mouse aortic EC. In vivo, female mice had significantly higher lipid accumulation within the aortas, impaired glucose tolerance, and lower endothelial-mediated vasorelaxation than males. Using the EC-lineage tracing approach, we found that female lesions had significantly lower rates of intraplaque neovascularization and endothelial-to-mesenchymal transition within advanced atherosclerotic lesions but higher incidents of missing EC lumen coverage and higher levels of oxidative products and apoptosis. RNA-seq analyses revealed that both mouse and human female EC had higher expression of genes associated with inflammation and apoptosis and lower expression of genes related to angiogenesis and oxidative phosphorylation than male EC.

CONCLUSIONS

Our study delineates critical sex-specific differences in EC relevant to proinflammatory, pro-oxidant, and angiogenic characteristics, which are entirely consistent with a vulnerable phenotype in females. Our results provide a biological basis for sex-specific proatherosclerotic mechanisms.

Coronary Plaque Characteristics and Underlying Mechanism of Acute Coronary Syndromes in Different Age Groups of Patients With Diabetes

BACKGROUND

High cardiovascular mortality has been reported in young patients with diabetes. However, the underlying pathology in different age groups of patients with diabetes has not been studied.

METHODS AND RESULTS

The aim of this study was to investigate the plaque characteristics and underlying pathology of acute coronary syndrome in different age groups of patients with or without diabetes in a large cohort. Patients who presented with acute coronary syndrome and underwent preintervention optical coherence tomography imaging were included. Culprit plaque was classified as plaque rupture, plaque erosion, or calcified plaque and stratified into 5 age groups. Plaque characteristics including features of vulnerability were examined by optical coherence tomography. Among 1394 patients, 482 (34.6%) had diabetes. Patients with diabetes, compared with patients without diabetes, had a higher prevalence of lipid-rich plaque (71.2% versus 64.8%, P=0.016), macrophage (72.0% versus 62.6%, P<0.001), and cholesterol crystal (27.6% versus 19.7%, P<0.001). Both diabetes and nondiabetes groups showed a decreasing trend in plaque erosion with age (patients with diabetes, P=0.020; patients without diabetes, P<0.001). Patients without diabetes showed an increasing trend with age in plaque rupture (P=0.004) and lipid-rich plaque (P=0.018), whereas patients with diabetes had a high prevalence of these vulnerable features at an early age that remained high across age groups.

CONCLUSIONS

Patients without diabetes showed an increasing trend with age in plaque rupture and lipid-rich plaque, whereas patients with diabetes had a high prevalence of these vulnerable features at an early age. These results suggest that atherosclerotic vascular changes with increased vulnerability start at a younger age in patients with diabetes.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifiers: NCT04523194, NCT03479723. URL: https://www.umin.ac.jp/ctr/. Unique identifier: UMIN000041692.

Residual risks and evolving atherosclerotic plaques

Atherosclerotic disease of the coronary and carotid arteries is the primary global cause of significant mortality and morbidity. The chronic occlusive diseases have changed the epidemiological landscape of health problems both in developed and the developing countries. Despite the enormous benefit of advanced revascularization techniques, use of statins, and successful attempts of targeting modifiable risk factors, like smoking and exercise in the last four decades, there is still a definite "residual risk" in the population, as evidenced by many prevalent and new cases every year. Here, we highlight the burden of the atherosclerotic diseases and provide substantial clinical evidence of the residual risks in these diseases despite advanced management settings, with emphasis on strokes and cardiovascular risks. We critically discussed the concepts and potential underlying mechanisms of the evolving atherosclerotic plaques in the coronary and carotid arteries. This has changed our understanding of the plaque biology, the progression of unstable vs stable plaques, and the evolution of plaque prior to the occurrence of a major adverse atherothrombotic event. This has been facilitated using intravascular ultrasound, optical coherence tomography, and near-infrared spectroscopy in the clinical settings to achieve surrogate end points. These techniques are now providing exquisite information on plaque size, composition, lipid volume, fibrous cap thickness and other features that were previously not possible with conventional angiography.

Integrin β Expression as a New Diagnostic Marker for Arteriovenous Thrombosis: A Single-Center Prospective Study

Integrin β plays an important role in the pathogenesis of thrombosis and inflammation, and it may be a shared pathogenic mechanism between arterial and venous thromboses. With the goal of identifying new treatment targets for thrombotic diseases and specific diagnostic markers for venous thromboembolism (VTE), this prospective clinical study was performed to clarify the relationship between integrin and thrombosis. The levels of integrin β1-3, interleukin-6 (IL-6), and C-reactive protein were significantly higher in patients with acute myocardial infarction (AMI; n = 44) and acute VTE (n = 43) compared to healthy controls (n = 33). The IL-6 and integrin β1-3 levels were also significantly higher in the AMI group compared to the VTE and control groups. Logistic regression analysis identified IL-6 and integrin β1-3 levels as independent risk factors for thrombotic disease. Based on the receiver-operating characteristic curve, Youden index, sensitivity, and specificity, the diagnostic accuracy value for VTE was greater than 0.8 when integrins β1, β2, and β3 were combined. Overall, these results suggest that integrin β levels can contribute to improving the diagnosis and treatment of arteriovenous thrombosis.

New Dawn for Atherosclerosis: Vascular Endothelial Cell Senescence and Death

Endothelial cells (ECs) form the inner linings of blood vessels, and are directly exposed to endogenous hazard signals and metabolites in the circulatory system. The senescence and death of ECs are not only adverse outcomes, but also causal contributors to endothelial dysfunction, an early risk marker of atherosclerosis. The pathophysiological process of EC senescence involves both structural and functional changes and has been linked to various factors, including oxidative stress, dysregulated cell cycle, hyperuricemia, vascular inflammation, and aberrant metabolite sensing and signaling. Multiple forms of EC death have been documented in atherosclerosis, including autophagic cell death, apoptosis, pyroptosis, NETosis, necroptosis, and ferroptosis. Despite this, the molecular mechanisms underlying EC senescence or death in atherogenesis are not fully understood. To provide a comprehensive update on the subject, this review examines the historic and latest findings on the molecular mechanisms and functional alterations associated with EC senescence and death in different stages of atherosclerosis.

Culprit plaque morphology determines inflammatory risk and clinical outcomes in acute coronary syndrome

AIMS

Rupture of the fibrous cap (RFC) and erosion of an intact fibrous cap (IFC) are the two predominant mechanisms causing acute coronary syndromes (ACS). It is uncertain whether clinical outcomes are different following RFC-ACS vs. IFC-ACS and whether this is affected by a specific inflammatory response. The prospective, translational OPTIcal-COherence Tomography in Acute Coronary Syndrome study programme investigates the impact of the culprit lesion phenotype on inflammatory profiles and prognosis in ACS patients.

METHODS AND RESULTS

This analysis included 398 consecutive ACS patients, of which 62% had RFC-ACS and 25% had IFC-ACS. The primary endpoint was a composite of cardiac death, recurrent ACS, hospitalization for unstable angina, and target vessel revascularization at 2 years [major adverse cardiovascular events (MACE+)]. Inflammatory profiling was performed at baseline and after 90 days. Patients with IFC-ACS had lower rates of MACE+ than those with RFC-ACS (14.3% vs. 26.7%, P = 0.02). In 368-plex proteomic analyses, patients with IFC-ACS showed lower inflammatory proteome expression compared with those with RFC-ACS, including interleukin-6 and proteins associated with the response to interleukin-1β. Circulating plasma levels of interleukin-1β decreased from baseline to 3 months following IFC-ACS (P < 0.001) but remained stable following RFC-ACS (P = 0.25). Interleukin-6 levels decreased in patients with RFC-ACS free of MACE+ (P = 0.01) but persisted high in those with MACE+.

CONCLUSION

This study demonstrates a distinct inflammatory response and a lower risk of MACE+ following IFC-ACS. These findings advance our understanding of inflammatory cascades associated with different mechanisms of plaque disruption and provide hypothesis generating data for personalized anti-inflammatory therapeutic allocation to ACS patients, a strategy that merits evaluation in future clinical trials.

A Nrf2-OSGIN1&2-HSP70 axis mediates cigarette smoke-induced endothelial detachment: implications for plaque erosion

AIMS

Endothelial erosion of plaques is responsible for ∼30% of acute coronary syndromes (ACS). Smoking is a risk factor for plaque erosion, which most frequently occurs on the upstream surface of plaques where the endothelium experiences elevated shear stress. We sought to recreate these conditions in vitro to identify potential pathological mechanisms that might be of relevance to plaque erosion.

METHODS AND RESULTS

Culturing human coronary artery endothelial cells (HCAECs) under elevated flow (shear stress of 7.5 Pa) and chronically exposing them to cigarette smoke extract (CSE) and tumour necrosis factor-alpha (TNFα) recapitulated a defect in HCAEC adhesion, which corresponded with augmented Nrf2-regulated gene expression. Pharmacological activation or adenoviral overexpression of Nrf2 triggered endothelial detachment, identifying Nrf2 as a mediator of endothelial detachment. Growth/Differentiation Factor-15 (GDF15) expression was elevated in this model, with protein expression elevated in the plasma of patients experiencing plaque erosion compared with plaque rupture. The expression of two Nrf2-regulated genes, OSGIN1 and OSGIN2, was increased by CSE and TNFα under elevated flow and was also elevated in the aortas of mice exposed to cigarette smoke in vivo. Knockdown of OSGIN1&2 inhibited Nrf2-induced cell detachment. Overexpression of OSGIN1&2 induced endothelial detachment and resulted in cell cycle arrest, induction of senescence, loss of focal adhesions and actin stress fibres, and disturbed proteostasis mediated in part by HSP70, restoration of which reduced HCAEC detachment. In ACS patients who smoked, blood concentrations of HSP70 were elevated in plaque erosion compared with plaque rupture.

CONCLUSION

We identified a novel Nrf2-OSGIN1&2-HSP70 axis that regulates endothelial adhesion, elevated GDF15 and HSP70 as biomarkers for plaque erosion in patients who smoke, and two therapeutic targets that offer the potential for reducing the risk of plaque erosion.

The role of endothelial shear stress, shear stress gradient, and plaque topography in plaque erosion

BACKGROUND AND AIMS

Plaque erosion is a common underlying cause of acute coronary syndromes. The role of endothelial shear stress (ESS) and endothelial shear stress gradient (ESSG) in plaque erosion remains unknown. We aimed to determine the role of ESS metrics and maximum plaque slope steepness in plaques with erosion versus stable plaques.

METHODS

This analysis included 46 patients/plaques from TOTAL and COMPLETE trials and Brigham and Women's Hospital's database who underwent angiography and OCT. Plaques were divided into those with erosion (n = 24) and matched stable coronary plaques (n = 22). Angiographic views were used to generate a 3-D arterial reconstruction, with centerlines merged from angiography and OCT pullback. Local ESS metrics were assessed by computational fluid dynamics. Among plaque erosions, the up- and down-slope (Δ lumen area/frame) was calculated for each culprit plaque.

RESULTS

Compared with stable plaque controls, plaques with an erosion were associated with higher max ESS (8.3 ± 4.8 vs. 5.0 ± 1.9 Pa, p = 0.02) and max ESSG any direction (9.2 ± 7.5 vs. 4.3 ± 3.11 Pa/mm, p = 0.005). Proximal erosion was associated with a steeper plaque upslope while distal erosion with a steeper plaque downslope. Max ESS and Max ESSG any direction were independent factors in the development of plaque erosion (OR 1.32, 95%CI 1.06-1.65, p = 0.014; OR 1.22, 95% CI 1.03-1.45, p = 0.009, respectively).

CONCLUSIONS

In plaques with similar luminal stenosis, plaque erosion was strongly associated with higher ESS, ESS gradients, and plaque slope as compared with stable plaques. These data support that ESS and slope metrics play a key role in the development of plaque erosion and may help prognosticate individual plaques at risk for future erosion.

Utility of optical coherence tomography in acute coronary syndromes

Studies utilizing intravascular imaging have replicated the findings of histopathological studies, identifying the most common substrates for acute coronary syndromes (ACS) as plaque rupture, erosion, and calcified nodule, with spontaneous coronary artery dissection, coronary artery spasm, and coronary embolism constituting the less common etiologies. The purpose of this review is to summarize the data from clinical studies that have used high-resolution intravascular optical coherence tomography (OCT) to assess culprit plaque morphology in ACS. In addition, we discuss the utility of intravascular OCT for effective treatment of patients presenting with ACS, including the possibility of culprit lesion-based treatment by percutaneous coronary intervention.

Coronary Computed Tomography Angiography Findings of Plaque Erosion

Compared with plaque rupture, plaque erosion has distinct features, which can be diagnosed only by intravascular optical coherence tomography. Computed tomography angiography (CTA) features of plaque erosion have not been reported. The aim of the present study was to identify the CTA features specific for plaque erosion in patients with non-ST-segment elevation acute coronary syndromes to enable a diagnosis of erosion without invasive procedures. Patients with non-ST-segment elevation acute coronary syndromes who underwent preintervention CTA and optical coherence tomography imaging of culprit lesions were enrolled. Plaque volume and high-risk plaque (HRP) features were assessed by CTA. Among 191 patients, plaque erosion was the underlying mechanism in 89 patients (46.6%) and plaque rupture in 102 patients (53.4%). The total plaque volume (TPV) was lower in plaque erosion than in plaque rupture (133.6 vs 168.8 mm³, p = 0.001). Plaque erosion had a lower prevalence of positive remodeling than plaque rupture (75.3% vs 87.3%, p = 0.033). As the number of HRP features decreased, plaque erosion became more prevalent (p = 0.014). In the multivariable logistic regression analysis, lower TPV and less prevalent HRP features were associated with a higher prevalence of plaque erosion. The addition of TPV ≤116 mm³ and HRP features ≤1 to the known predictors significantly increased the area under the curve of the plaque erosion prediction receiver operator characteristics. Plaque erosion, compared with plaque rupture, had a lower plaque volume and less prevalent HRP features. CTA may be helpful for identifying the underlying pathology of acute coronary syndromes.

New Insights into Pathophysiology and New Risk Factors for ACS

Cardiovascular disease still represents the main cause of mortality worldwide. Despite huge improvements, atherosclerosis persists as the principal pathological condition, both in stable and acute presentation. Specifically, acute coronary syndromes have received substantial research and clinical attention in recent years, contributing to improve overall patients' outcome. The identification of different evolution patterns of the atherosclerotic plaque and coronary artery disease has suggested the potential need of different treatment approaches, according to the mechanisms and molecular elements involved. In addition to traditional risk factors, the finer portrayal of other metabolic and lipid-related mediators has led to higher and deep knowledge of atherosclerosis, providing potential new targets for clinical management of the patients. Finally, the impressive advances in genetics and non-coding RNAs have opened a wide field of research both on pathophysiology and the therapeutic side that are extensively under investigation.

Underlying mechanisms of thrombus formation/growth in atherothrombosis and deep vein thrombosis

Thrombosis remains a leading cause of death worldwide despite technological advances in prevention, diagnosis, and treatment. The traditional view of arterial thrombus formation is that it is a platelet-dependent process, whereas that of venous thrombus formation is a coagulation-dependent process. Current pathological and basic studies on atherothrombosis and venous thrombosis have revealed the diverse participation of platelet and coagulation activation mechanisms in both thrombus initiation and growth processes during clinical thrombotic events. Atherosclerotic plaque cell-derived tissue factor contributes to fibrin formation and platelet aggregation. The degree of plaque disruption and a blood flow alteration promote atherothrombotic occlusion. While blood stasis/turbulent flow due to luminal stenosis itself initiates venous thrombus formation. The coagulation factor XI-driven propagation phase of blood coagulation plays a major role in venous thrombus growth, but a minor role in hemostasis. These lines of evidence indicate that atherothrombosis onset is affected by the thrombogenic potential of atherosclerotic plaques, the plaque disruption size, and an alteration in blood flow. Upon onset of venous thrombosis, enhancement of the propagation phase of blood coagulation under blood stasis and a hypercoagulable state contribute to large thrombus formation.

The Role of Neutrophils in Lower Limb Peripheral Artery Disease: State of the Art and Future Perspectives

In recent years, increasing attention has been paid to the role of neutrophils in cardiovascular (CV) disease (CVD) with evidence supporting their role in the initiation, progression, and rupture of atherosclerotic plaque. Although these cells have long been considered as terminally differentiated cells with a relatively limited spectrum of action, recent research has revealed intriguing novel cellular functions, including neutrophil extracellular trap (NET) generation and inflammasome activation, which have been linked to several human diseases, including CVD. While most research to date has focused on the role of neutrophils in coronary artery and cerebrovascular diseases, much less information is available on lower limb peripheral artery disease (PAD). PAD is a widespread condition associated with great morbidity and mortality, though physician and patient awareness of the disease remains low. To date, several studies have produced some evidence on the role of certain biomarkers of neutrophil activation in this clinical setting. However, the etiopathogenetic role of neutrophils, and in particular of some of the newly discovered mechanisms, has yet to be fully elucidated. In the future, complementary assessment of neutrophil activity should improve CV risk stratification and provide personalized treatments to patients with PAD. This review aims to summarize the basic principles and recent advances in the understanding of neutrophil biology, current knowledge about the role of neutrophils in atherosclerosis, as well as available evidence on their role of PAD.

Coronary artery plaque rupture and erosion: Role of wall shear stress profiling and biological patterns in acute coronary syndromes

AIMS

Wall shear stress (WSS) is involved in coronary artery plaque pathological mechanisms and modulation of gene expression. This study aims to provide a comprehensive haemodynamic and biological description of unstable (intact-fibrous-cap, IFC, and ruptured-fibrous-cap, RFC) and stable (chronic coronary syndrome, CCS) plaques and investigate any correlation between WSS and molecular pathways.

METHODS AND RESULTS

We enrolled 24 CCS and 25 Non-ST Elevation Myocardial Infarction-ACS patients with IFC (n = 11) and RFC (n = 14) culprit lesions according to optical coherence tomography analysis. A real-time PCR primer array was performed on peripheral blood mononuclear cells for 17 different molecules whose expression is linked to WSS. Computational fluid dynamics simulations were performed in high-fidelity 3D-coronary artery anatomical models for three patients per group. A total of nine genes were significantly overexpressed in the unstable patients as compared to CCS patients, with no differences between IFC and RFC groups (GPX1, MMP1, MMP9, NOS3, PLA2G7, PI16, SOD1, TIMP1, and TFRC) while four displayed different levels between IFC and RFC groups (TNFα, ADAMTS13, EDN1, and LGALS8). A significantly higher WSS was observed in the RFC group (p < 0.001) compared to the two other groups. A significant correlation was observed between TNFα (p < 0.001), EDN1 (p = 0.036), and MMP9 (p = 0.005) and WSS values in the RFC group.

CONCLUSIONS

Our data demonstrate that IFC and RFC plaques are subject to different WSS conditions and gene expressions, suggesting that WSS profiling may play an essential role in the plaque instability characterization with relevant diagnostic and therapeutic implications in the era of precision medicine.

The Vascular System: Anatomical, Physiological, Pathological, and Aging Considerations

The vascular system is one of the earliest recognized anatomical systems. It is composed of 3 parts; arterial, capillary, and venous, each with their own unique anatomy and physiology. Blood flow through this system is compromised in aging, atherosclerosis and peripheral vascular disease, and the practicing anesthesiologist must understand both the physiology and pathophysiology of the vascular tree.

The neutrophil: A key resourceful agent in immune‐mediated vasculitis

The term "vasculitis" refers to a group of rare immune-mediated diseases characterized by the dysregulated immune system attacking blood vessels located in any organ of the body, including the skin, lungs, and kidneys. Vasculitides are classified according to the size of the vessel that is affected. Although this observation is not specific to small-, medium-, or large-vessel vasculitides, patients show a high circulating neutrophil-to-lymphocyte ratio, suggesting the direct or indirect involvement of neutrophils in these diseases. As first responders to infection or inflammation, neutrophils release cytotoxic mediators, including reactive oxygen species, proteases, and neutrophil extracellular traps. If not controlled, this dangerous arsenal can injure the vascular system, which acts as the main transport route for neutrophils, thereby amplifying the initial inflammatory stimulus and the recruitment of immune cells. This review highlights the ability of neutrophils to "set the tone" for immune cells and other cells in the vessel wall. Considering both their long-established and newly described roles, we extend their functions far beyond their direct host-damaging potential. We also review the roles of neutrophils in various types of primary vasculitis, including immune complex vasculitis, anti-neutrophil cytoplasmic antibody-associated vasculitis, polyarteritis nodosa, Kawasaki disease, giant cell arteritis, Takayasu arteritis, and Behçet's disease.

Neutrophils in aging and aging‐related pathologies

Over the past millennia, life expectancy has drastically increased. While a mere 25 years during Bronze and Iron ages, life expectancy in many European countries and in Japan is currently above 80 years. Such an increase in life expectancy is a result of improved diet, life style, and medical care. Yet, increased life span and aging also represent the most important non-modifiable risk factors for several pathologies including cardiovascular disease, neurodegenerative diseases, and cancer. In recent years, neutrophils have been implicated in all of these pathologies. Hence, this review provides an overview of how aging impacts neutrophil production and function and conversely how neutrophils drive aging-associated pathologies. Finally, we provide a perspective on how processes of neutrophil-driven pathologies in the context of aging can be targeted therapeutically.

Single-Cell RNA Sequencing of Peripheral Blood Mononuclear Cells From Acute Myocardial Infarction

Background

Acute myocardial infarction (AMI) can occur in patients with atherosclerotic disease, with or without plaque rupture. Previous studies have indicated a set of immune responses to plaque rupture. However, the specific circulating immune cell subsets that mediate inflammatory plaque rupture remain elusive.

Methods

Ten AMI patients were enrolled in our study (five with and five without plaque rupture; plaque characteristics were identified by optical coherence tomography). By single-cell RNA sequencing, we analyzed the transcriptomic profile of peripheral blood mononuclear cells.

Results

We identified 27 cell clusters among 82,550 cells, including monocytes, T cells, NK cells, B cells, megakaryocytes, and CD34⁺ cells. Classical and non-classical monocytes constitute the major inflammatory cell types, and pro-inflammatory genes such as CCL5, TLR7, and CX3CR1 were significantly upregulated in patients with plaque rupture, while the neutrophil activation and degranulation genes FPR2, MMP9, and CLEC4D were significantly expressed in the intermediate monocytes derived from patients without plaque rupture. We also found that CD4⁺ effector T cells may contribute to plaque rupture by producing a range of cytokines and inflammatory-related chemokines, while CD8⁺ effector T cells express more effector molecules in patients without plaque rupture, such as GZMB, GNLY, and PRF1, which may contribute to the progress of plaque erosion. Additionally, NK and B cells played a significant role in activating inflammatory cells and promoting chemokine production in the plaque rupture. Cell–cell communication elaborated characteristics in signaling pathways dominated by inflammatory activation of classical monocytes in patients with plaque rupture.

Conclusions

Our studies demonstrate that the circulating immune cells of patients with plaque rupture exhibit highly pro-inflammatory characteristics, while plaque erosion is mainly associated with intermediate monocyte amplification, neutrophil activation, and degranulation. These findings may provide novel targets for the precise treatment of patients with AMI.

Role of Intracoronary Imaging in Acute Coronary Syndromes

Intravascular imaging with optical coherence tomography (OCT) and intravascular ultrasound provides superior visualization of the culprit plaques for acute coronary syndromes (ACS) compared with coronary angiography. Combined with angiography, intravascular imaging can be used to instigate ‘precision therapy’ for ACS. Post-mortem histopathology identified atherothrombosis at the exposed surface of a ruptured fibrous cap as the main cause of ACS. Further histopathological studies identified intact fibrous caps and calcified nodules as other culprit lesions for ACS. These plaque types were subsequently also identified on intravascular imaging, particularly with the high-resolution OCT. The less-common non-atherothrombotic causes of ACS are coronary artery spasm, coronary artery dissection, and coronary embolism. In this review, the authors provide an overview of clinical studies using intravascular imaging with OCT in the diagnosis and management of ACS.

High-Risk Coronary Plaque Features: A Narrative Review

Advances in coronary plaque imaging over the last few decades have led to an increased interest in the identification of novel high-risk plaque features that are associated with cardiovascular events. Existing practices focus on risk stratification and lipid monitoring for primary and secondary prevention of cardiac events, which is limited by a lack of assessment and treatment of vulnerable plaque. In this review, we summarize the multitude of studies that have identified plaque, haemodynamic and patient factors associated with risk of acute coronary syndrome. Future progress in multi-modal imaging strategies and in our understanding of high-risk plaque features could expand treatment options for coronary disease and improve patient outcomes.

Semaglutide treatment attenuates vessel remodelling in ApoE-/- mice following vascular injury and blood flow perturbation

Background and aims

Randomized clinical studies have shown a reduction in cardiovascular outcomes with glucagon-like peptide 1 receptor agonist (GLP-1RA) treatment with the hypothesized mechanisms being an underlying effect on atherosclerosis. Here, we aimed to assess the pharmacological effects of semaglutide in an atheroprone murine model that recapitulates central mechanisms related to vascular smooth muscle cell (VSMC) phenotypic switching and endothelial dysfunction known to operate within the atherosclerotic plaque.

Methods

In study A, we employed an electrical current to the carotid artery in ApoE-/- mice to induce severe VSMC injury and death, after which the arteries were allowed to heal for 4 weeks. In study B, a constrictive cuff was added for 6 h at the site of the healed segment to induce a disturbance in blood flow.

Results

Compared to vehicle, semaglutide treatment reduced the intimal and medial area by ∼66% (p = 0.007) and ∼11% (p = 0.0002), respectively. Following cuff placement, expression of the pro-inflammatory marker osteopontin and macrophage marker Mac-2 was reduced (p < 0.05) in the semaglutide-treated group compared to vehicle. GLP-1R were not expressed in murine carotid artery and human coronary vessels with and without atherosclerotic plaques, and semaglutide treatment did not affect proliferation of cultured primary human VSMCs.

Conclusions

Semaglutide treatment reduced vessel remodelling following electrical injury and blood flow perturbation in an atheroprone mouse model. This effect appears to be driven by anti-inflammatory and -proliferative mechanisms independent of GLP-1 receptor-mediated signalling in the resident vascular cells. This mechanism of action may be important for cardiovascular protection.

Endothelial Dysfunction Induced by Extracellular Neutrophil Traps Plays Important Role in the Occurrence and Treatment of Extracellular Neutrophil Traps-Related Disease

Many articles have demonstrated that extracellular neutrophil traps (NETs) are often described as part of the antibacterial function. However, since the components of NETs are non-specific, excessive NETs usually cause inflammation and tissue damage. Endothelial dysfunction (ED) caused by NETs is the major focus of tissue damage, which is highly related to many inflammatory diseases. Therefore, this review summarizes the latest advances in the primary and secondary mechanisms between NETs and ED regarding inflammation as a mediator. Moreover, the detailed molecular mechanisms with emphasis on the disadvantages from NETs are elaborated: NETs can use its own enzymes, release particles as damage-associated molecular patterns (DAMPs) and activate the complement system to interact with endothelial cells (ECs), drive ECs damage and eventually aggravate inflammation. In view of the role of NETs-induced ED in different diseases, we also discussed possible molecular mechanisms and the treatments of NETs-related diseases.

Complement C5a induces the generation of neutrophil extracellular traps by inhibiting mitochondrial STAT3 to promote the development of arterial thrombosis

Background

Thrombotic events cannot be completely prevented by antithrombotics, implicating a therapeutic gap due to inflammation, a not yet sufficiently addressed mechanism. Neutrophil extracellular traps (NETs) are an essential interface between inflammation and thrombosis, but exactly how the NETotic process is initiated and maintained during arterial thrombosis remains incompletely understood.

Methods and results

We found that the plasma concentrations of C5a were higher in patients with ST-elevation myocardial infarction (STEMI) than in patients with angina and higher in mice with left common carotid artery (LCCA) thrombosis induced by FeCl₃ than in control mice. We observed that the thrombus area and weight were decreased and that NET formation in the thrombi was reduced in the group treated with the selective C5aR1 receptor inhibitor PMX53 compared with the NaCl group. In vitro, NETosis was observed when C5a was added to neutrophil cultures, and this effect was reversed by PMX53. In addition, our data showed that C5a increased the production of mitochondrial reactive oxygen species (ROS) and that the promotion of NET formation by C5a was mitochondrial ROS (Mito-ROS) dependent. Furthermore, we found that C5a induced the production of Mito-ROS by inhibiting mitochondrial STAT3 activity.

Conclusions

By inhibiting mitochondrial STAT3 to elicit Mito-ROS generation, C5a triggers the generation of NETs to promote the development of arterial thrombosis. Hence, our study identifies complement C5a as a potential new target for the treatment and prevention of thrombosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12959-022-00384-0.

Inflammation and atherosclerosis: signaling pathways and therapeutic intervention

Atherosclerosis is a chronic inflammatory vascular disease driven by traditional and nontraditional risk factors. Genome-wide association combined with clonal lineage tracing and clinical trials have demonstrated that innate and adaptive immune responses can promote or quell atherosclerosis. Several signaling pathways, that are associated with the inflammatory response, have been implicated within atherosclerosis such as NLRP3 inflammasome, toll-like receptors, proprotein convertase subtilisin/kexin type 9, Notch and Wnt signaling pathways, which are of importance for atherosclerosis development and regression. Targeting inflammatory pathways, especially the NLRP3 inflammasome pathway and its regulated inflammatory cytokine interleukin-1β, could represent an attractive new route for the treatment of atherosclerotic diseases. Herein, we summarize the knowledge on cellular participants and key inflammatory signaling pathways in atherosclerosis, and discuss the preclinical studies targeting these key pathways for atherosclerosis, the clinical trials that are going to target some of these processes, and the effects of quelling inflammation and atherosclerosis in the clinic.

Immune Mechanisms of Plaque Instability

Inflammation crucially drives atherosclerosis from disease initiation to the emergence of clinical complications. Targeting pivotal inflammatory pathways without compromising the host defense could compliment therapy with lipid-lowering agents, anti-hypertensive treatment, and lifestyle interventions to address the substantial residual cardiovascular risk that remains beyond classical risk factor control. Detailed understanding of the intricate immune mechanisms that propel plaque instability and disruption is indispensable for the development of novel therapeutic concepts. In this review, we provide an overview on the role of key immune cells in plaque inception and progression, and discuss recently identified maladaptive immune phenomena that contribute to plaque destabilization, including epigenetically programmed trained immunity in myeloid cells, pathogenic conversion of autoreactive regulatory T-cells and expansion of altered leukocytes due to clonal hematopoiesis. From a more global perspective, the article discusses how systemic crises such as acute mental stress or infection abruptly raise plaque vulnerability and summarizes recent advances in understanding the increased cardiovascular risk associated with COVID-19 disease. Stepping outside the box, we highlight the role of gut dysbiosis in atherosclerosis progression and plaque vulnerability. The emerging differential role of the immune system in plaque rupture and plaque erosion as well as the limitations of animal models in studying plaque disruption are reviewed.

Targeted delivery of protein arginine deiminase-4 inhibitors to limit arterial intimal NETosis and preserve endothelial integrity

AIMS

Recent evidence suggests that 'vulnerable plaques', which have received intense attention as underlying mechanism of acute coronary syndromes over the decades, actually rarely rupture and cause clinical events. Superficial plaque erosion has emerged as a growing cause of residual thrombotic complications of atherosclerosis in an era of increased preventive measures including lipid lowering, antihypertensive therapy, and smoking cessation. The mechanisms of plaque erosion remain poorly understood, and we currently lack validated effective diagnostics or therapeutics for superficial erosion. Eroded plaques have a rich extracellular matrix, an intact fibrous cap, sparse lipid, and few mononuclear cells, but do harbour neutrophil extracellular traps (NETs). We recently reported that NETs amplify and propagate the endothelial damage at the site of arterial lesions that recapitulate superficial erosion in mice. We showed that genetic loss of protein arginine deiminase (PAD)-4 function inhibited NETosis and preserved endothelial integrity. The current study used systemic administration of targeted nanoparticles to deliver an agent that limits NETs formation to probe mechanisms of and demonstrate a novel therapeutic approach to plaque erosion that limits endothelial damage.

METHODS AND RESULTS

We developed Collagen IV-targeted nanoparticles (Col IV NP) to deliver PAD4 inhibitors selectively to regions of endothelial cell sloughing and collagen IV-rich basement membrane exposure. We assessed the binding capability of the targeting ligand in vitro and evaluated Col IV NP targeting to areas of denuded endothelium in vivo in a mouse preparation that recapitulates features of superficial erosion. Delivery of the PAD4 inhibitor GSK484 reduced NET accumulation at sites of intimal injury and preserved endothelial continuity.

CONCLUSIONS

NPs directed to Col IV show selective uptake and delivery of their payload to experimentally eroded regions, illustrating their translational potential. Our results further support the role of PAD4 and NETs in superficial erosion.

Distinct pathological mechanisms distinguish acute coronary syndrome caused by plaque erosion from plaque rupture

PURPOSE OF REVIEW

The current systematic review aims to provide novel insights into the distinct pathological features of acute coronary syndrome (ACS) with intact fibrous cap, also known as 'plaque erosion'. A more detailed understanding of its underlying pathomechanisms provides the basis for future personalized therapeutic approaches to ACS.

RECENT FINDINGS

In the past years, a mounting proportion of evidence point towards the concept of plaque erosion being responsible for more than one-third of all cases of ACS and representing an autonomous ACS-causing entity driven by biomechanical forces, immunological alternations and systemic elevation of inflammatory mediators. First pilot studies proved a therapeutic paradigm shift from primary PCI at the ACS-causing culprit lesion to systemic therapies in patients with ACS caused by plaque erosion.

SUMMARY

This review provides the current status of the broad basic and clinical studies focused to the topic of plaque erosion: a new ACS-causing pathophysiology with different pathological aspects providing appropriate implications for personalized therapies in ACS.

Plaque Erosion: A Distinctive Pathological Mechanism of Acute Coronary Syndrome

Plaque erosion (PE) is one of the most important pathological mechanisms underlying acute coronary syndrome (ACS). The incidence of PE is being increasingly recognized owing to the development and popularization of intracavitary imaging. Unlike traditional vulnerable plaques, eroded plaques have unique pathological characteristics. Moreover, recent studies have revealed that there are differences in the physiopathological mechanisms, biomarkers, and clinical outcomes between PE and plaque rupture (PR). Accurate diagnosis and treatment of eroded plaques require an understanding of the pathogenesis of PE. In this review, we summarize recent scientific discoveries of the pathological characteristics, mechanisms, biomarkers, clinical strategies, and prognosis in patients with PE.

Plaque erosion and acute coronary syndromes: phenotype, molecular characteristics and future directions

Although acute coronary syndromes (ACS) remain one of the leading causes of death, the clinical presentation has changed over the past three decades with a decline in the incidence of ST-segment elevation myocardial infarction (STEMI) and an increase in non-STEMI. This epidemiological shift is at least partially explained by changes in plaque biology as a result of the widespread use of statins. Historically, atherosclerotic plaque rupture of the fibrous cap was thought to be the main culprit in ACS. However, plaque erosion with an intact fibrous cap is now responsible for about one third of ACS and up to two thirds of non-STEMI. Two major research approaches have enabled a better understanding of plaque erosion. First, advanced intravascular imaging has provided opportunities for an 'optical biopsy' and extensive phenotyping of coronary plaques in living patients. Second, basic science experiments have shed light on the unique molecular characteristics of plaque erosion. At present, patients with ACS are still uniformly treated with coronary stents irrespective of the underlying pathobiology. However, pilot studies indicate that patients with plaque erosion might be treated conservatively without coronary stenting. In this Review, we discuss the patient phenotype and the molecular characteristics in atherosclerotic plaque erosion and provide our vision for a potential major shift in the management of patients with plaque erosion.

Vascular smooth muscle cells in atherosclerosis: time for a re-assessment

Vascular smooth muscle cells (VSMCs) are key participants in both early and late-stage atherosclerosis. VSMCs invade the early atherosclerotic lesion from the media, expanding lesions, but also forming a protective fibrous cap rich in extracellular matrix to cover the 'necrotic' core. Hence, VSMCs have been viewed as plaque-stabilizing, and decreased VSMC plaque content-often measured by expression of contractile markers-associated with increased plaque vulnerability. However, the emergence of lineage-tracing and transcriptomic studies has demonstrated that VSMCs comprise a much larger proportion of atherosclerotic plaques than originally thought, demonstrate multiple different phenotypes in vivo, and have roles that might be detrimental. VSMCs down-regulate contractile markers during atherosclerosis whilst adopting alternative phenotypes, including macrophage-like, foam cell-like, osteochondrogenic-like, myofibroblast-like, and mesenchymal stem cell-like. VSMC phenotypic switching can be studied in tissue culture, but also now in the media, fibrous cap and deep-core region, and markedly affects plaque formation and markers of stability. In this review, we describe the different VSMC plaque phenotypes and their presumed cellular and paracrine functions, the regulatory mechanisms that control VSMC plasticity, and their impact on atherogenesis and plaque stability.

Optical Coherence Tomography of Plaque Erosion: JACC Focus Seminar Part 2/3

Plaque erosion, a distinct histopathological and clinical entity, accounts for over 30% of acute coronary syndromes (ACS). Optical coherence tomography allows in vivo diagnosis of plaque erosion. Local flow perturbation with activation of Toll-like receptor 2 and CD8⁺ T cells and subsequent desquamation of endothelium and neutrophil extracellular trap formation contribute to mechanisms of plaque erosion. Compared with ACS patients with plaque rupture, those with plaque erosion are younger, have fewer traditional cardiovascular risk factors, have lower plaque burden, and are more likely to present with non-ST-segment elevation ACS. Early evidence suggests that in patients with ACS caused by plaque erosion, antithrombotic therapy without stenting may be a safe and effective option. Future randomized trials are needed to validate these findings. Clinical studies to develop noninvasive point-of-care biomarkers that distinguish plaque rupture from erosion, and to test novel therapies that target molecular pathways involved in plaque erosion are needed.

Optical Coherence Tomography of Coronary Plaque Progression and Destabilization: JACC Focus Seminar Part 3/3

The development of optical coherence tomography (OCT) has revolutionized our understanding of coronary artery disease. In vivo OCT research has paralleled with advances in computational fluid dynamics, providing additional insights in the various hemodynamic factors influencing plaque growth and stability. Recent OCT studies introduced a new concept of plaque healing in relation to clinical presentation. In addition to known mechanisms of acute coronary syndromes such as plaque rupture and plaque erosion, a new classification of calcified plaque was recently reported. This review will focus on important new insights that OCT has provided in recent years into coronary plaque development, progression, and destabilization, with a focus on the role of local hemodynamics and endothelial shear stress, the layered plaque (signature of previous subclinical plaque destabilization and healing), and the calcified culprit plaque.

New Insight Into Neutrophils: A Potential Therapeutic Target for Cerebral Ischemia

Ischemic stroke is one of the main issues threatening human health worldwide, and it is also the main cause of permanent disability in adults. Energy consumption and hypoxia after ischemic stroke leads to the death of nerve cells, activate resident glial cells, and promote the infiltration of peripheral immune cells into the brain, resulting in various immune-mediated effects and even contradictory effects. Immune cell infiltration can mediate neuronal apoptosis and aggravate ischemic injury, but it can also promote neuronal repair, differentiation and regeneration. The central nervous system (CNS), which is one of the most important immune privileged parts of the human body, is separated from the peripheral immune system by the blood-brain barrier (BBB). Under physiological conditions, the infiltration of peripheral immune cells into the CNS is controlled by the BBB and regulated by the interaction between immune cells and vascular endothelial cells. As the immune response plays a key role in regulating the development of ischemic injury, neutrophils have been proven to be involved in many inflammatory diseases, especially acute ischemic stroke (AIS). However, neutrophils may play a dual role in the CNS. Neutrophils are the first group of immune cells to enter the brain from the periphery after ischemic stroke, and their exact role in cerebral ischemia remains to be further explored. Elucidating the characteristics of immune cells and their role in the regulation of the inflammatory response may lead to the identification of new potential therapeutic strategies. Thus, this review will specifically discuss the role of neutrophils in ischemic stroke from production to functional differentiation, emphasizing promising targeted interventions, which may promote the development of ischemic stroke treatments in the future.

Optical Coherence Tomography in Acute Coronary Syndromes

Advances in intravascular imaging have enabled assessment of the underlying plaque morphology in acute coronary syndromes, which allows for the initiation of individualized therapy. The atherothrombotic substrates for acute coronary syndromes consist of plaque rupture, erosion, and calcified nodule, whereas spontaneous coronary artery dissection, coronary artery spasm, and coronary embolism constitute rarer nonatherothrombotic etiologies. This review provides a brief overview of the data from clinical studies that have used intravascular optical coherence tomography to assess the culprit plaque morphology. We discuss the usefulness of intravascular imaging for effective treatment of patients presenting with acute coronary syndromes by percutaneous coronary intervention.

Long noncoding RNA SNHG12 integrates a DNA-PK-mediated DNA damage response and vascular senescence

Long noncoding RNAs (lncRNAs) are emerging regulators of biological processes in the vessel wall; however, their role in atherosclerosis remains poorly defined. We used RNA sequencing to profile lncRNAs derived specifically from the aortic intima of Ldlr ^-/- mice on a high-cholesterol diet during lesion progression and regression phases. We found that the evolutionarily conserved lncRNA small nucleolar host gene-12 (SNHG12) is highly expressed in the vascular endothelium and decreases during lesion progression. SNHG12 knockdown accelerated atherosclerotic lesion formation by 2.4-fold in Ldlr ^-/- mice by increased DNA damage and senescence in the vascular endothelium, independent of effects on lipid profile or vessel wall inflammation. Conversely, intravenous delivery of SNHG12 protected the tunica intima from DNA damage and atherosclerosis. LncRNA pulldown in combination with liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis showed that SNHG12 interacted with DNA-dependent protein kinase (DNA-PK), an important regulator of the DNA damage response. The absence of SNHG12 reduced the DNA-PK interaction with its binding partners Ku70 and Ku80, abrogating DNA damage repair. Moreover, the anti-DNA damage agent nicotinamide riboside (NR), a clinical-grade small-molecule activator of NAD⁺, fully rescued the increases in lesional DNA damage, senescence, and atherosclerosis mediated by SNHG12 knockdown. SNHG12 expression was also reduced in pig and human atherosclerotic specimens and correlated inversely with DNA damage and senescent markers. These findings reveal a role for this lncRNA in regulating DNA damage repair in the vessel wall and may have implications for chronic vascular disease states and aging.

Investigation of Wall Shear Stress in Cardiovascular Research and in Clinical Practice-From Bench to Bedside

In the 1900s, researchers established animal models experimentally to induce atherosclerosis by feeding them with a cholesterol-rich diet. It is now accepted that high circulating cholesterol is one of the main causes of atherosclerosis; however, plaque localization cannot be explained solely by hyperlipidemia. A tremendous amount of studies has demonstrated that hemodynamic forces modify endothelial athero-susceptibility phenotypes. Endothelial cells possess mechanosensors on the apical surface to detect a blood stream-induced force on the vessel wall, known as "wall shear stress (WSS)", and induce cellular and molecular responses. Investigations to elucidate the mechanisms of this process are on-going: on the one hand, hemodynamics in complex vessel systems have been described in detail, owing to the recent progress in imaging and computational techniques. On the other hand, investigations using unique in vitro chamber systems with various flow applications have enhanced the understanding of WSS-induced changes in endothelial cell function and the involvement of the glycocalyx, the apical surface layer of endothelial cells, in this process. In the clinical setting, attempts have been made to measure WSS and/or glycocalyx degradation non-invasively, for the purpose of their diagnostic utilization. An increasing body of evidence shows that WSS, as well as serum glycocalyx components, can serve as a predicting factor for atherosclerosis development and, most importantly, for the rupture of plaques in patients with high risk of coronary heart disease.

Low-density lipoproteins cause atherosclerotic cardiovascular disease: pathophysiological, genetic, and therapeutic insights: a consensus statement from the European Atherosclerosis Society Consensus Panel

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Differential immunological signature at the culprit site distinguishes acute coronary syndrome with intact from acute coronary syndrome with ruptured fibrous cap: results from the prospective translational OPTICO-ACS study

AIMS

Acute coronary syndromes with intact fibrous cap (IFC-ACS), i.e. caused by coronary plaque erosion, account for approximately one-third of ACS. However, the underlying pathophysiological mechanisms as compared with ACS caused by plaque rupture (RFC-ACS) remain largely undefined. The prospective translational OPTICO-ACS study programme investigates for the first time the microenvironment of ACS-causing culprit lesions (CL) with intact fibrous cap by molecular high-resolution intracoronary imaging and simultaneous local immunological phenotyping.

METHODS AND RESULTS

The CL of 170 consecutive ACS patients were investigated by optical coherence tomography (OCT) and simultaneous immunophenotyping by flow cytometric analysis as well as by effector molecule concentration measurements across the culprit lesion gradient (ratio local/systemic levels). Within the study cohort, IFC caused 24.6% of ACS while RFC-ACS caused 75.4% as determined and validated by two independent OCT core laboratories. The IFC-CL were characterized by lower lipid content, less calcification, a thicker overlying fibrous cap, and largely localized near a coronary bifurcation as compared with RFC-CL. The microenvironment of IFC-ACS lesions demonstrated selective enrichment in both CD4+ and CD8+ T-lymphocytes (+8.1% and +11.2%, respectively, both P < 0.05) as compared with RFC-ACS lesions. T-cell-associated extracellular circulating microvesicles (MV) were more pronounced in IFC-ACS lesions and a significantly higher amount of CD8+ T-lymphocytes was detectable in thrombi aspirated from IFC-culprit sites. Furthermore, IFC-ACS lesions showed increased levels of the T-cell effector molecules granzyme A (+22.4%), perforin (+58.8%), and granulysin (+75.4%) as compared with RFC plaques (P < 0.005). Endothelial cells subjected to culture in disturbed laminar flow conditions, i.e. to simulate coronary flow near a bifurcation, demonstrated an enhanced adhesion of CD8+T cells. Finally, both CD8+T cells and their cytotoxic effector molecules caused endothelial cell death, a key potential pathophysiological mechanism in IFC-ACS.

CONCLUSIONS

The OPTICO-ACS study emphasizes a novel mechanism in the pathogenesis of IFC-ACS, favouring participation of the adaptive immune system, particularly CD4+ and CD8+ T-cells and their effector molecules. The different immune signatures identified in this study advance the understanding of coronary plaque progression and may provide a basis for future development of personalized therapeutic approaches to ACS with IFC.

TRIAL REGISTRATION

The study was registered at clinicalTrials.gov (NCT03129503).