Decreased numbers of regulatory T cells are associated with human atherosclerotic lesion vulnerability and inversely correlate with infiltrated mature dendritic cells

Targeting immune cell recruitment in atherosclerosis

Atherosclerosis is the primary underlying cause of myocardial infarction and stroke. Atherosclerotic cardiovascular disease is characterized by a chronic inflammatory reaction in medium-to-large-sized arteries, with its onset and perpetuation driven by leukocytes infiltrating the subendothelial space. Activation of endothelial cells triggered by hyperlipidaemia and lipoprotein retention in the arterial intima initiates the accumulation of pro-inflammatory leukocytes in the arterial wall, fostering the progression of atherosclerosis. This inflammatory response is coordinated by an array of soluble mediators, namely cytokines and chemokines, that amplify inflammation both locally and systemically and are complemented by tissue-specific molecules that regulate the homing, adhesion and transmigration of leukocytes. Despite abundant evidence from mouse models, only a few therapies targeting leukocytes in atherosclerosis have been assessed in humans. The major challenges for the clinical translation of these therapies include the lack of tissue specificity and insufficient selectivity of inhibition strategies. In this Review, we discuss the latest research on receptor-ligand pairs and interactors that regulate leukocyte influx into the inflamed artery wall, primarily focusing on studies that used pharmacological interventions. We also discuss mechanisms that promote the resolution of inflammation and highlight how major findings from these research areas hold promise as potential therapeutic strategies for atherosclerotic cardiovascular disease.

Hypercholesterolemia and inflammation-Cooperative cardiovascular risk factors

BACKGROUND

Maintaining low concentrations of plasma low-density lipoprotein cholesterol (LDLc) over time decreases the number of LDL particles trapped within the artery wall, slows the progression of atherosclerosis and delays the age at which mature atherosclerotic plaques develop. This substantially reduces the lifetime risk of atherosclerotic cardiovascular disease (ASCVD) events. In this context, plaque development and vulnerability result not only from lipid accumulation but also from inflammation.

RESULTS

Changes in the composition of immune cells, including macrophages, dendritic cells, T cells, B cells, mast cells and neutrophils, along with altered cytokine and chemokine release, disrupt the equilibrium between inflammation and anti-inflammatory mechanisms at plaque sites. Considering that it is not a competition between LDLc and inflammation, but instead that they are partners in crime, the present narrative review aims to give an overview of the main inflammatory molecular pathways linked to raised LDLc concentrations and to describe the impact of lipid-lowering approaches on the inflammatory and lipid burden. Although remarkable changes in LDLc are driven by the most recent lipid lowering combinations, the relative reduction in plasma C-reactive protein appears to be independent of the magnitude of LDLc lowering.

CONCLUSION

Identifying clinical biomarkers of inflammation (e.g. interleukin-6) and possible targets for therapy holds promise for monitoring and reducing the ASCVD burden in suitable patients.

Immunometabolism in atherosclerosis: a new understanding of an old disease

Atherosclerosis, a chronic inflammatory condition, remains a leading cause of death globally, necessitating innovative approaches to target pro-atherogenic pathways. Recent advancements in the field of immunometabolism have highlighted the crucial interplay between metabolic pathways and immune cell function in atherogenic milieus. Macrophages and T cells undergo dynamic metabolic reprogramming to meet the demands of activation and differentiation, influencing plaque progression. Furthermore, metabolic intermediates intricately regulate immune cell responses and atherosclerosis development. Understanding the metabolic control of immune responses in atherosclerosis, known as athero-immunometabolism, offers new avenues for preventive and therapeutic interventions. This review elucidates the emerging intricate interplay between metabolism and immunity in atherosclerosis, underscoring the significance of metabolic enzymes and metabolites as key regulators of disease pathogenesis and therapeutic targets.

Exploring the common mechanisms and biomarker ST8SIA4 of atherosclerosis and ankylosing spondylitis through bioinformatics analysis and machine learning

Background

Atherosclerosis (AS) is a major contributor to cerebrovascular and cardiovascular events. There is growing evidence that ankylosing spondylitis is closely linked to AS, often co-occurring with it; however, the shared pathogenic mechanisms between the two conditions are not well understood. This study employs bioinformatics approaches to identify common biomarkers and pathways between AS and ankylosing spondylitis.

Methods

Gene expression datasets for AS (GSE100927, GSE28829, GSE155512) and ankylosing spondylitis (GSE73754, GSE25101) were obtained from the Gene Expression Omnibus (GEO). Differential expression genes (DEGs) and module genes for AS and ankylosing spondylitis were identified using the Limma R package and weighted gene co-expression network analysis (WGCNA) techniques, respectively. The machine learning algorithm SVM-RFE was applied to pinpoint promising biomarkers, which were then validated in terms of their expression levels and diagnostic efficacy in AS and ankylosing spondylitis, using two separate GEO datasets. Furthermore, the interaction of the key biomarker with the immune microenvironment was investigated via the CIBERSORT algorithm, single-cell analysis was used to identify the locations of common diagnostic markers.

Results

The dataset GSE100927 contains 524 DEGs associated with AS, whereas dataset GSE73754 includes 1,384 genes categorized into modules specific to ankylosing spondylitis. Analysis of these datasets revealed an overlap of 71 genes between the DEGs of AS and the modular genes of ankylosing spondylitis. Utilizing the SVM-RFE algorithm, 15 and 24 central diagnostic genes were identified in datasets GSE100927 and GSE73754, respectively. Further validation of six key genes using external datasets confirmed ST8SIA4 as a common diagnostic marker for both conditions. Notably, ST8SIA4 is upregulated in samples from both diseases. Additionally, ROC analysis confirmed the robust diagnostic utility of ST8SIA4. Moreover, analysis through CIBERSORT suggested an association of the ST8SIA4 gene with the immune microenvironment in both disease contexts. Single-cell analysis revealed that ST8SIA4 is primarily expressed in Macrophages, Monocytes, T cells, and CMPs.

Conclusion

This study investigates the role of ST8SIA4 as a common diagnostic gene and the involvement of the lysosomal pathway in both AS and ankylosing spondylitis. The findings may yield potential diagnostic biomarkers and offer new insights into the shared pathogenic mechanisms underlying these conditions.

Molecular fingerprints of cardiovascular toxicities of immune checkpoint inhibitors

Immune checkpoint inhibitors (ICIs) have revolutionized cancer therapy by unleashing the power of the immune system against malignant cells. However, their use is associated with a spectrum of adverse effects, including cardiovascular complications, which can pose significant clinical challenges. Several mechanisms contribute to cardiovascular toxicity associated with ICIs. First, the dysregulation of immune checkpoints, such as cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) and programmed cell death protein-1 (PD-1) and its ligand (PD-L1), and molecular mimicry with cardiac autoantigens, leads to immune-related adverse events, including myocarditis and vasculitis. These events result from the aberrant activation of T cells against self-antigens within the myocardium or vascular endothelium. Second, the disruption of immune homeostasis by ICIs can lead to autoimmune-mediated inflammation of cardiac tissues, manifesting as cardiac dysfunction and heart failure, arrhythmias, or pericarditis. Furthermore, the upregulation of inflammatory cytokines, particularly tumor necrosis factor-alpha, interferon-γ, interleukin-1β, interleukin-6, and interleukin-17 contributes to cardiac and endothelial dysfunction, plaque destabilization, and thrombosis, exacerbating cardiovascular risk on the long term. Understanding the intricate mechanisms of cardiovascular side effects induced by ICIs is crucial for optimizing patient care and to ensure the safe and effective integration of immunotherapy into a broader range of cancer treatment protocols. The clinical implications of these mechanisms underscore the importance of vigilant monitoring and early detection of cardiovascular toxicity in patients receiving ICIs. Future use of these key pathological mediators as biomarkers may aid in prompt diagnosis of cardiotoxicity and will allow timely interventions.

Regulatory T-cell frequency and function in acute myocardial infarction patients and its correlation with ventricular dysfunction

A high percentage of patients with acute coronary syndrome develop heart failure due to the ischemic event. Regulatory T (Treg) cells are lymphocytes with suppressive capacity that control the immune response and include the conventional CD4+ CD25hi Foxp3+ cells and the CD4+ CD25var CD69+ LAP+ Foxp3- IL-10+ cells. No human follow-up studies focus on Treg cells' behavior after infarction and their possible relationship with ventricular function as a sign of postischemic cardiac remodeling. This study aimed to analyze, by flow cytometry, the circulating levels of CD69+ Treg cells and CD4+ CD25hi Foxp3+ cells, their IL-10+ production as well as their function in patients with acute myocardial infarction (AMI), and its possible relation with ventricular dysfunction. We found a significant difference in the percentage of CD4+ CD25hi Foxp3+ cells and IL-10+ MFI in patients with AMI at 72 hours compared with the healthy control group, and the levels of these cells were reduced 6 months post-AMI. Regarding the suppressive function of CD4+ CD25+ regulatory cells, they were dysfunctional at 3 and 6 months post-AMI. The frequency of CD69+ Treg cells was similar between patients with AMI at 72 hours postinfarction and the control groups. Moreover, the frequency of CD69+ Treg cells at 3 and 6 months postischemic event did not vary over time. Treg cells play a role in regulating inflammation after an AMI, and its function may be compromised in this pathology. This work is the first report to evaluate CD69+ Foxp3- Treg cells in AMI patients.

Immune checkpoint inhibitor-associated cardiovascular toxicities: A review

Immune checkpoint inhibitors (ICIs) have revolutionary effects on therapeutic strategies for multiple malignancies. Their efficacy depends on their ability to reactivate the host immune system to fight cancer cells. However, adverse reactions to ICIs are common and involve several organs, limiting their use in clinical practice. Although the incidence of cardiovascular toxicity is relatively low, it is associated with serious consequences and high mortality rates. The primary cardiovascular toxicities include myocarditis, pericarditis, Takotsubo syndrome, arrhythmia, vasculitis, acute coronary syndrome, and venous thromboembolism. Currently, the mechanism underlying ICI-associated cardiovascular toxicity remains unclear and underexplored. The diagnosis and monitoring of ICI-associated cardiovascular toxicities mainly include the following indicators: symptoms, signs, laboratory examination, electrocardiography, imaging, and pathology. Treatments are based on the grade of cardiovascular toxicity and mainly include drug withdrawal, corticosteroid therapy, immunosuppressants, and conventional cardiac treatment. This review focuses on the incidence, underlying mechanisms, clinical manifestations, diagnoses, and treatment strategies.

Association between Immune Checkpoint Inhibitors and Atherosclerotic Cardiovascular Disease Risk: Another Brick in the Wall

In recent years, immune checkpoint inhibitors have significantly changed the field of oncology, emerging as first-line treatment, either alone or in combination with other regimens, for numerous malignancies, improving overall survival and progression-free survival in these patients. However, immune checkpoint inhibitors might also cause severe or fatal immune-related adverse events, including adverse cardiovascular events. Initially, myocarditis was recognized as the main immune checkpoint inhibitor-related cardiac event, but our knowledge of other potential immune-related cardiovascular adverse events continues to broaden. Recently, preclinical and clinical data seem to support an association between immune checkpoint inhibitors and accelerated atherosclerosis as well as atherosclerotic cardiovascular events such as cardiac ischemic disease, stroke, and peripheral artery disease. In this review, by offering a comprehensive overview of the pivotal role of inflammation in atherosclerosis, we focus on the potential molecular pathways underlying the effects of immune checkpoint inhibitors on cardiovascular diseases. Moreover, we provide an overview of therapeutic strategies for cancer patients undergoing immunotherapy to prevent the development of cardiovascular diseases.

Role of cytokines and Th17/Tregs imbalance in the pathogenesis of otitis media with effusion. Modulation of Notch1/Hes1/mTORC1/S6k1 signalling pathway underlies the protective effect of astaxanthin

Otitis media with effusion (OME) is a recurrent middle ear inflammatory condition. It may be complicated by acquired hearing loss and speech impairment especially in children. Accordingly, the current study aimed to assess the role of cytokines and the imbalance of Th17/Tregs in the pathogenesis of OME. Additionally, the protective effect of astaxanthin and its mechanisms related to Notch1/ Hes1/mTORC1/S6K1 signalling were investigated.

METHODS

Forty-eight children were grouped as follow: G1: control healthy group G2: acute otitis media (AOM) group, G3: OME group. In the lipopolysaccharide (LPS) induced OME rat model, 15 rats were randomised into: G1: normal control group, G2: LPS group, and G3: astaxanthin treated group.

RESULTS

Biochemical analysis of the children's peripheral blood samples showed that IL1β, IL-2, IL-4, IL-6, IL-17, and IL-23 were significantly elevated, while TGF-β was significantly decreased in AOM and OME patients (group 2 and 3). In the LPS- induced OME rat model, astaxanthin treatment resulted in suppression of IL-17, IL-6, TNF-α, Muc5A, TFF3, NICD, Hes1, mTORC1, and S6K1 in rat middle ear mucosa. Furthermore, astaxanthin significantly downregulated RORγ while upregulating FoxP3 and restored the balance between Th17/Tregs. Moreover, astaxanthin improved the histopathological picture of the inflamed middle ear mucosa.

CONCLUSIONS

Proinflammatory cytokines as well as Th17/Tregs imbalance play a crucial role in the pathogenesis of AOM and OME. Additionally, astaxanthin alleviated LPS- induced OME in rats through suppression of Notch1/ Hes1/mTORC1/S6K1 pathway, and regulation of Th17/Tregs.

Inflammation Resolution in the Cardiovascular System: Arterial Hypertension, Atherosclerosis, and Ischemic Heart Disease

Significance: Chronic inflammation has emerged as a major underlying cause of many prevalent conditions in the Western world, including cardiovascular diseases. Although targeting inflammation has emerged as a promising avenue by which to treat cardiovascular disease, it is also associated with increased risk of infection. Recent Advances: Though previously assumed to be passive, resolution has now been identified as an active process, mediated by unique immunoresolving mediators and mechanisms designed to terminate acute inflammation and promote tissue repair. Recent work has determined that failures of resolution contribute to chronic inflammation and the progression of human disease. Specifically, failure to produce pro-resolving mediators and the impaired clearance of dead cells from inflamed tissue have been identified as major mechanisms by which resolution fails in disease. Critical Issues: Drawing from a rapidly expanding body of experimental and clinical studies, we review here what is known about the role of inflammation resolution in arterial hypertension, atherosclerosis, myocardial infarction, and ischemic heart disease. For each, we discuss the involvement of specialized pro-resolving mediators and pro-reparative cell types, including T regulatory cells, myeloid-derived suppressor cells, and macrophages. Future Directions: Pro-resolving therapies offer the promise of limiting chronic inflammation without impairing host defense. Therefore, it is imperative to better understand the mechanisms underlying resolution to identify therapeutic targets. Antioxid. Redox Signal. 40, 292-316.

Identification of key pyroptosis-related genes and microimmune environment among peripheral arterial beds in atherosclerotic arteries

Atherosclerosis is a chronic inflammatory disease characterized with innate and adaptive immunity but also involves pyroptosis. Few studies have explored the role of pyroptosis in advanced atherosclerotic plaques from different vascular beds. Here we try to identify the different underlying function of pyroptosis in the progression of atherosclerosis between carotid arteries and femoral. arteries. We extracted gene expression levels from 55 advanced carotid or femoral atherosclerotic plaques. The pyroptosis score of each sample was calculated by single-sample-gene-set enrichment analysis (ssGSEA). We then divided the samples into two clusters: high pyroptosis scores cluster (PyroptosisScoreH cluster) and low pyroptosis scores cluster (PyroptosisScoreL cluster), and assessed functional enrichment and immune cell infiltration in the two clusters. Key pyroptosis related genes were identified by the intersection between results of Cytoscape and LASSO (Least Absolute Shrinkage and Selection Operator) regression analysis. Finally, all key pyroptosis related genes were validated in vitro. We found all but one of the 29 carotid plaque samples belonged to the PyroptosisScoreH cluster and the majority (19 out of 26) of femoral plaques were part of the PyroptosisScoreL cluster. Atheromatous plaque samples in the PyroptosisScoreL cluster had higher proportions of gamma delta T cells, M2 macrophages, myeloid dendritic cells (DCs), and cytotoxic lymphocytes (CTLs), but lower proportions of endothelial cells (ECs). Immune full-activation pathways (e.g., NOD-like receptor signaling pathway and NF-kappa B signaling pathway) were highly enriched in the PyroptosisScoreH cluster. The key pyroptosis related genes GSDMD, CASP1, NLRC4, AIM2, and IL18 were upregulated in advanced carotid atherosclerotic plaques. We concluded that compared to advanced femoral atheromatous plaques, advanced carotid atheromatous plaques were of higher grade of pyroptosis. GSDMD, CASP1, NLRC4, AIM2, and IL18 were the key pyroptosis related genes, which might provide a new sight in the prevention of fatal strokes in advanced carotid atherosclerosis.

Immunotherapy-Associated Atherosclerosis: A Comprehensive Review of Recent Findings and Implications for Future Research

Purpose of the Review

Even as immune checkpoint inhibitors (ICIs) have transformed the lifespan of many patients, they may also trigger acceleration of long-term cardiovascular disease. Our review aims to examine the current landscape of research on ICI-mediated atherosclerosis and address key questions regarding its pathogenesis and impact on patient management.

Recent Findings

Preclinical mouse models suggest that T cell dysregulation and proatherogenic cytokine production are key contributors to plaque development after checkpoint inhibition. Clinical data also highlight the significant burden of atherosclerotic cardiovascular disease (ASCVD) in patients on immunotherapy, although the value of proactively preventing and treating ASCVD in this population remains an open area of inquiry. Current treatment options include dietary/lifestyle modification and traditional medications to manage hypertension, hyperlipidemia, and diabetes risk factors; no current targeted therapies exist.

Summary

Early identification of high-risk patients is crucial for effective preventive strategies and timely intervention. Future research should focus on refining screening tools, elucidating targetable mechanisms driving ICI atherosclerosis, and evaluating long-term cardiovascular outcomes in cancer survivors who received immunotherapy. Moreover, close collaboration between oncologists and cardiologists is essential to optimize patient outcomes.

Prognostic value of CT-derived fractional flow reserve and fat attenuation index in patients with suspected coronary artery disease: a sex-disaggregated analyses

BACKGROUND

There are sex differences in many risk factors associated with coronary artery disease (CAD). CT-derived fractional flow reserve (CT-FFR) and fat attenuation index (FAI) have been shown to independently predict cardiovascular events. We aimed to examine the impact of sex on the prognostic value of CT-FFR and FAI in suspected CAD patients, and to examine the incremental prognostic value of FAI over CT-FFR in both sex.

METHODS

A total of 1334 consecutive suspected CAD subjects who underwent coronary computed tomographic angiography (CCTA) were retrospectively collected. We divided the patients into males and females and calculated CT-FFR and FAI data from CCTA images. Kaplan-Meier analysis was used to assess the risk of major adverse cardiovascular events (MACE) stratified by CT-FFR and FAI in both sex. Cox regression models were used to assess the incremental prognostic value of FAI by adding the variable to a model that included CT-FFR and clinical variables.

RESULTS

During a median follow-up of 2.08 years, 212 patients had MACE. CT-FFR ≤ 0.80 was significantly associated with MACE in both sex. FAI value of left anterior descending artery (FAI[LAD]) and FAI value of left circumflex (FAI[LCX]) ≥ 70.1 were significantly associated with MACE in females. FAI[LCX] added incremental prognostic value over clinical and CT-FFR variables in females, with hazard ratio (HR) 3.230 (1.982-5.265, P = 0.000), Harrel's C 0.669 (P < 0.001), net reclassification improvement (NRI) 0.161 (0.073-0.260, P < 0.001), and integrated discrimination index (IDI) 0.036 (0.008-0.090, P = 0.010). FAI[LAD] did not enhance risk prediction in females (Harrel's C 0.643, P = 0.054; NRI 0.041, P = 0.189; IDI 0.005, P = 0.259). The decision curve analysis demonstrated that the model including FAI[LCX] resulted in the highest net benefit.

CONCLUSIONS

In suspected CAD patients, the prognostic value of CT-FFR is not significantly biased by sex. The prognostic value of FAI[LAD] and FAI[LCX] were significantly associated with MACE in females, but not males. FAI[LCX], not FAI[LAD], added incremental prognostic value over CT-FFR and might enhance CT-FFR risk stratification in females.

Chloroquine Alleviates Atherosclerosis by Modulating Regulatory T Cells Through the ATM/AMPK/mTOR Signaling Pathway in ApoE -/- Mice

BACKGROUND

Clinical observation suggests the atheroprotective effect of chloroquine and its derivatives, while its mechanism remains unclear. This study aimed to observe the protective effect of chloroquine against atherosclerosis and explore the underlying mechanism.

METHODS

Ataxia telangiectasia mutated (ATM) wild-type or haploinsufficient apolipoprotein-E-knockout (ATM+/+ApoE-/- or ATM+/-ApoE-/-) mice were treated with different dosages of chloroquine. Anti-CD25 antibody was used to deplete natural Tregs in ATM+/+ApoE-/- mice. The atherosclerotic burden in different groups of mice was comprehensively evaluated by H&E staining and Masson staining. The effect of chloroquine on the regulatory T cells (Tregs) was assessed in vivo and in vitro by flow cytometry and immunohistochemical staining. The expression of related proteins was detected by real-time polymerase chain reaction and western blotting.

RESULTS

In ATM+/+ApoE-/- mice, chloroquine alleviated atherosclerotic lesions, stabilized the plaque, and increased Treg counts in the atherosclerotic lesions and spleens. However, in ATM haploinsufficient mice (ATM+/-ApoE-/-), chloroquine no longer prevented atherosclerosis or impacted Treg counts. Abolishing Treg cells using an anti-CD25 antibody in vivo abrogated the atheroprotective effect of chloroquine. In vitro, chloroquine promoted the differentiation of Tregs from naïve T cells, which was accompanied by enhanced ATM/AMP-activated protein kinase (AMPK) activity and reduced downstream mammalian target of rapamycin (mTOR) activity.

DISCUSSION

These findings suggest that chloroquine ameliorates atherosclerosis and stabilizes plaque by modulating Tregs differentiation through the regulation of the ATM/AMPK/mTOR pathway.

Oxidized Phospholipid oxPAPC Alters Regulatory T-Cell Differentiation and Decreases Their Protective Function in Atherosclerosis in Mice

BACKGROUND

Regulatory T cells (Tregs) are protective in atherosclerosis but reduced during disease progression due to cell death and loss of stability. However, the mechanisms of Treg dysfunction remain unknown. Oxidized phospholipids are abundant in atherosclerosis and can activate innate immune cells, but little is known regarding their impact on T cells. Given Treg loss during atherosclerosis progression and oxidized phospholipid levels in the plaque microenvironment, we investigated whether oxidized 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphocholine (oxPAPC), an oxidized phospholipid associated with atherosclerotic plaques, alters Treg differentiation and function.

METHODS

CD4+ T cells were polarized to Treg, T helper (Th) 1, and Th17 cells with or without oxPAPC and assessed by flow cytometry. Gene expression in oxPAPC-treated Tregs was analyzed by bulk RNA sequencing. Functional studies of oxPAPC-induced Tregs were performed by coculturing Tregs with CellTrace Violet-labeled cells in vitro, and by adoptively transferring Tregs to hyperlipidemic Ldlr-/- mice to measure atherosclerosis progression.

RESULTS

Compared with controls, oxPAPC-treated Tregs were less viable, but surviving cells expressed higher levels of the Th1-associated markers T-bet, CXCR3, and IFN (interferon)-γ. Th1 and Th17 skewing cultures were unaltered by oxPAPC. IFN-γ is linked to Treg instability, thus Treg polarization experiments were repeated using Ifngr1-/- CD4+ T cells. IFNγR1 (INF gamma receptor 1) deficiency did not improve cell viability in oxPAPC-treated Tregs; however, T-bet and IFN-γ expression was not increased in surviving cells suggesting a role for IFN-γsignaling. OxPAPC-treated Tregs were less suppressive in vitro, and adoptive transfer studies in hyperlipidemic Ldlr-/- mice showed that oxPAPC-induced Tregs possessed altered tissue homing and were insufficient to inhibit atherosclerosis progression.

CONCLUSIONS

OxPAPC elicits Treg-specific changes altering Treg differentiation and inducing a Th1-like phenotype in surviving cells partially through IFN-γ signaling. This is biologically relevant as oxPAPC-treated Tregs do not reduce atherosclerosis progression in Ldlr-/- mice. This study supports the role of oxidized phospholipids in negatively impacting Treg differentiation and atheroprotective function.

Regulatory T Cells in Atherosclerosis: Is Adoptive Cell Therapy Possible?

Atherosclerosis is an insidious vascular disease with an asymptomatic debut and development over decades. The aetiology and pathogenesis of atherosclerosis are not completely clear. However, chronic inflammation and autoimmune reactions play a significant role in the natural course of atherosclerosis. The pathogenesis of atherosclerosis involves damage to the intima, immune cell recruitment and infiltration of cells such as monocytes/macrophages, neutrophils, and lymphocytes into the inner layer of vessel walls, and the accumulation of lipids, leading to vascular inflammation. The recruited immune cells mainly have a pro-atherogenic effect, whereas CD4+ regulatory T (Treg) cells are another heterogeneous group of cells with opposite functions that suppress the pathogenic immune responses. Present in low numbers in atherosclerotic plaques, Tregs serve a protective role, maintaining immune homeostasis and tolerance by suppressing pro-inflammatory immune cell subsets. Compelling experimental data suggest that various Treg cell-based approaches may be important in the treatment of atherosclerosis. Here we highlight the most recent advances in our understanding of the roles of FOXP3-expressing CD4+ Treg cells in the atherogenic process and discuss potential translational strategies for the treatment of atherosclerosis by Treg manipulation.

An Increased Understanding of the Association Between Atherosclerosis and Immune Checkpoint Inhibitors

PURPOSE OF REVIEW

Immune checkpoint inhibitor (ICI) therapy activates the host immune system to promote tumor cell death. This activation of the immune system can lead to off-target immune-related adverse events (irAEs). There is an established link between inflammation and atherosclerosis. The purpose of this manuscript is to review the existing body of literature discussing the potential association between ICI treatment and atherosclerosis.

RECENT FINDINGS

Pre-clinical studies suggest that ICI therapy may lead to T-cell-mediated progression of atherosclerosis. Recent retrospective clinical studies have shown higher rates of myocardial infarction and stroke with ICI therapy, particularly in patients with pre-existing cardiovascular risk factors. Additionally, small observational cohort studies have used imaging modalities to demonstrate higher rates of atherosclerotic progression with ICI treatment. Early pre-clinical and clinical evidence suggests an association between ICI treatment and the progression of atherosclerosis. However, these findings are preliminary, and adequately powered prospective studies are needed to demonstrate a conclusive association. As ICI therapy is increasingly used to treat a variety of solid tumors, it is important to evaluate and mitigate the potential adverse atherosclerotic effects of ICI treatment.

A novel interleukin-2-based fusion molecule, HCW9302, differentially promotes regulatory T cell expansion to treat atherosclerosis in mice

Atherosclerosis is a chronic inflammatory disease caused by deposition of oxidative low-density lipoprotein (LDL) in the arterial intima which triggers the innate immune response through myeloid cells such as macrophages. Regulatory T cells (Tregs) play an important role in controlling the progression or regression of atherosclerosis by resolving macrophage-mediated inflammatory functions. Interleukin-2 (IL-2) signaling is essential for homeostasis of Tregs. Since recombinant IL-2 has an unfavorable pharmacokinetic profile limiting its therapeutic use, we constructed a fusion protein, designated HCW9302, containing two IL-2 domains linked by an extracellular tissue factor domain. We found that HCW9302 exhibited a longer serum half-life with an approximately 1000-fold higher affinity for the IL-2Rα than IL-2. HCW9302 could be administered to mice at a dosing range that expanded and activated Tregs but not CD4⁺ effector T cells. In an ApoE^-/- mouse model, HCW9302 treatment curtailed the progression of atherosclerosis through Treg activation and expansion, M2 macrophage polarization and myeloid-derived suppressor cell induction. HCW9302 treatment also lessened inflammatory responses in the aorta. Thus, HCW9302 is a potential therapeutic agent to expand and activate Tregs for treatment of inflammatory and autoimmune diseases.

The Involvement of Cx43 in JNK1/2-Mediated Endothelial Mechanotransduction and Human Plaque Progression

Atherosclerotic lesions preferentially develop at bifurcations, characterized by non-uniform shear stress (SS). The aim of this study was to investigate SS-induced endothelial activation, focusing on stress-regulated mitogen-activated protein kinases (MAPK) and downstream signaling, and its relation to gap junction proteins, Connexins (Cxs). Human umbilical vein endothelial cells were exposed to flow ("mechanical stimulation") and stimulated with TNF-α ("inflammatory stimulation"). Phosphorylated levels of MAPKs (c-Jun N-terminal kinase (JNK1/2), extracellular signal-regulated kinase (ERK), and p38 kinase (p38K)) were quantified by flow cytometry, showing the activation of JNK1/2 and ERK. THP-1 cell adhesion under non-uniform SS was suppressed by the inhibition of JNK1/2, not of ERK. Immunofluorescence staining and quantitative real-time PCR demonstrated an induction of c-Jun and c-Fos and of Cx43 in endothelial cells by non-uniform SS, and the latter was abolished by JNK1/2 inhibition. Furthermore, plaque inflammation was analyzed in human carotid plaques (n = 40) using immunohistochemistry and quanti-gene RNA-assays, revealing elevated Cx43⁺ cell counts in vulnerable compared to stable plaques. Cx43⁺ cell burden in the plaque shoulder correlated with intraplaque neovascularization and lipid core size, while an inverse correlation was observed with fibrous cap thickness. Our results constitute the first report that JNK1/2 mediates Cx43 mechanoinduction in endothelial cells by atheroprone shear stress and that Cx43 is expressed in human carotid plaques. The correlation of Cx43⁺ cell counts with markers of plaque vulnerability implies its contribution to plaque progression.

Atherosclerosis With Immune Checkpoint Inhibitor Therapy: Evidence, Diagnosis, and Management: JACC: CardioOncology State-of-the-Art Review

As the clinical applications of immune checkpoint inhibitors (ICIs) expand, our knowledge of the potential adverse effects of these drugs continues to broaden. Emerging evidence supports the association between ICI therapy with accelerated atherosclerosis and atherosclerotic cardiovascular (CV) events. We discuss the biological plausibility and the clinical evidence supporting an effect of inhibition of these immune checkpoints on atherosclerotic CV disease. Further, we provide a perspective on potential diagnostic and pharmacological strategies to reduce atherosclerotic risk in ICI-treated patients. Our understanding of the pathophysiology of ICI-related atherosclerosis is in its early stages. Further research is needed to identify the mechanisms linking ICI therapy to atherosclerosis, leverage the insight that ICI therapy provides into CV biology, and develop robust approaches to manage the expanding cohort of patients who may be at risk for atherosclerotic CV disease.

Role of Sex in Atherosclerosis: Does Sex Matter?

PURPOSE OF REVIEW

Atherosclerosis is the largest cause of death in the western world with the role of sex yet to be determined. The purpose of this review is to investigate the role sex may play in the development of atherosclerosis.

RECENT FINDINGS

Differences in plaque burden play a role in atherosclerotic outcome. Men have a higher prevalence of plaque burden, while women have less plaque rupture, necrotic core, and calcium. Differences in hormones, vascular anatomy, and overall lifestyle all play a role. Estrogen's cardioprotective effect is well known, but there is a lack of consensus on testosterone's role. There are varying rates of atherosclerosis between the sexes. Studies have also shown varying differences in the progression of plaque and the type of plaques between sexes. Further investigations need to be done to solidify the role sex may play as a variable in the development of atherosclerosis and how that may impact future treatment goals.

Costimulatory and coinhibitory molecules of B7-CD28 family in cardiovascular atherosclerosis: A review

Accumulating evidence supports the active involvement of vascular inflammation in atherosclerosis pathogenesis. Vascular inflammatory events within atherosclerotic plaques are predominated by innate antigen-presenting cells (APCs), including dendritic cells, macrophages, and adaptive immune cells such as T lymphocytes. The interaction between APCs and T cells is essential for the initiation and progression of vascular inflammation during atherosclerosis formation. B7-CD28 family members that provide either costimulatory or coinhibitory signals to T cells are important mediators of the cross-talk between APCs and T cells. The balance of different functional members of the B7-CD28 family shapes T cell responses during inflammation. Recent studies from both mouse and preclinical models have shown that targeting costimulatory molecules on APCs and T cells may be effective in treating vascular inflammatory diseases, especially atherosclerosis. In this review, we summarize recent advances in understanding how APC and T cells are involved in the pathogenesis of atherosclerosis by focusing on B7-CD28 family members and provide insight into the immunotherapeutic potential of targeting B7-CD28 family members in atherosclerosis.

Implications of regulatory T cells in non-lymphoid tissue physiology and pathophysiology

Treg cells have been initially described as gatekeepers for the control of autoimmunity, as they can actively suppress the activity of other immune cells. However, their role goes beyond this as Treg cells further control immune responses during infections and tumor development. Furthermore, Treg cells can acquire additional properties for e.g., the control of tissue homeostasis. This is instructed by a specific differentiation program and the acquisition of effector properties unique to Treg cells in non-lymphoid tissues. These tissue Treg cells can further adapt to their tissue environment and acquire distinct functional properties through specific transcription factors activated by a combination of tissue derived factors, including tissue-specific antigens and cytokines. In this review, we will focus on recent findings extending our current understanding of the role and differentiation of these tissue Treg cells. As such we will highlight the importance of tissue Treg cells for tissue maintenance, regeneration, and repair in adipose tissue, muscle, CNS, liver, kidney, reproductive organs, and the lung.

TREM-1 Modulates Dendritic Cells Maturation and Dendritic Cell-Mediated T-Cell Activation Induced by ox-LDL

Atherosclerosis is a chronic inflammatory disease. The triggering receptor expressed on myeloid cells-1 (TREM-1) plays a crucial role in inflammatory diseases; recently, it was identified as a major upstream proatherogenic receptor, but its mechanism is still unclear. In this study, we explore the role of TREM-1 on dendritic cells maturation and inflammatory responses induced by ox-LDL and its possible mechanism. Human dendritic cells were differentiated from blood monocytes and treated with ox-LDL. Naive autologous T cells were cocultured with pretreated DCs or treated directly. The expression of TREM-1 and inflammatory factors were evaluated by real-time PCR, western blot, and ELISA methods. And the expression of immune factors to evaluate the DCs maturation and T-cell activation were determined by the FACS. Our study showed that ox-LDL induced TREM-1 expression, DC maturation, and T-cell activation. T cells exposed to ox-LDL-treated DCs produced interferon-γ and interleukin-17 (IL-17). Blocking TREM-1 suppressed the DC maturation, showing lower expression of CD1a, CD40, CD86, CD83, and HLA-DR, and limited their production of tumor necrosis factor-alpha (TNF-α), IL-1β, IL-6, and monocyte chemoattractant protein-1 (MCP-1), meanwhile increased transforming growth factor-β(TGF-β) and IL-10 production. Ox-LDL induced miR-155, miR-27, Let-7c, and miR-185 expression; however, TREM-1 inhibiting decreased miRNA-155 expression. Furthermore, silencing miRNA-155 restores SOCS1 repression induced by ox-LDL. Experiments with T cells derived from carotid atherosclerotic plaques or healthy individuals showed similar results. Our results uncover a new link between ox-LDL and TREM-1 and may provide insight into this interaction in the context of atherosclerosis.

Immune Checkpoint Therapies and Atherosclerosis: Mechanisms and Clinical Implications: JACC State-of-the-Art Review

Immune checkpoint inhibitor therapy has revolutionized the treatment of advanced malignancies in recent years. Numerous reports have detailed the myriad of possible adverse inflammatory effects of immune checkpoint therapies, including within the cardiovascular system. However, these reports have been largely limited to myocarditis. The critical role of inflammation and adaptive immunity in atherosclerosis has been well characterized in preclinical studies, and several emerging clinical studies indicate a potential role of immune checkpoint targeting therapies in the development and exacerbation of atherosclerosis. In this review, we provide an overview of the role of T-cell immunity in atherogenesis and describe the molecular effects and clinical associations of both approved and investigational immune checkpoint therapy on atherosclerosis. We also highlight the role of cholesterol metabolism in oncogenesis and discuss the implications of these associations on future treatment and monitoring of atherosclerotic cardiovascular disease in the oncologic population receiving immune checkpoint therapy.

Atherosclerosis: nexus of vascular dynamics and cellular cross talks

Cardiovascular diseases (CVDs) are the foremost cause of mortality worldwide. Atherosclerosis is the underlying pathology behind CVDs. Atherosclerosis is manifested predominantly by lipid deposition, plaque formation, and inflammation in vascular intima. Initiation and progression of plaque require many years. With aging, atherosclerotic plaques become vulnerable. Localization of these plaques in the coronary artery leads to myocardial infarction. A complete understanding of the pathophysiology of this multifaceted disease is necessary to achieve the clinical goal to provide early diagnosis and the best therapeutics. The triggering factors of atherosclerosis are biomechanical forces, hyperlipidemia, and chronic inflammatory response. The current review focuses on crucial determinants involved in the disease, such as location, hemodynamic factors, oxidation of low-density lipoproteins, and the role of endothelial cells, vascular smooth muscle cells, and immune cells, and better therapeutic targets.

Inflammation Resolution: Implications for Atherosclerosis

Resolution is an active and highly coordinated process that occurs in response to inflammation to limit tissue damage and promote repair. When the resolution program fails, inflammation persists. It is now understood that failed resolution is a major underlying cause of many chronic inflammatory diseases. Here, we will review the major failures of resolution in atherosclerosis, including the imbalance of proinflammatory to pro-resolving mediator production, impaired clearance of dead cells, and functional changes in immune cells that favor ongoing inflammation. In addition, we will briefly discuss new concepts that are emerging as possible regulators of resolution and highlight the translational significance for the field.

Difference of immune cell infiltration between stable and unstable carotid artery atherosclerosis

Atherosclerotic plaque instability contributes to ischaemic stroke and myocardial infarction. This study is to compare the abundance and difference of immune cell subtypes within unstable atherosclerotic tissues. CIBERSORT was used to speculate the proportions of 22 immune cell types based on a microarray of atherosclerotic carotid artery samples. R software was utilized to illustrate the bar plot, heat map and vioplot. The immune cell landscape in atherosclerosis was diverse, dominated by M2 macrophages, M0 macrophages, resting CD4 memory T cells and CD8 T cells. There was a significant difference in resting CD4 memory T cells (p = 0.032), T cells follicular helper (p = 0.033), M0 (p = 0.047) and M2 macrophages (p = 0.012) between stable and unstable atherosclerotic plaques. Compared with stable atherosclerotic plaques, unstable atherosclerotic plaques had a higher percentage of M2 macrophages. Moreover, correlation analysis indicated that the percentage of naïve CD4 T cells was strongly correlated with that of gamma delta T cells (r = 0.93, p < 0.001), while memory B cells were correlated with plasma cells (r = 0.85, p < 0.001). In summary, our study explored the abundance and difference of specific immune cell subgroups at unstable plaques, which would aid new immunotherapies for atherosclerosis.

Mechanistic Insight into PPARγ and Tregs in Atherosclerotic Immune Inflammation

Atherosclerosis (AS) is the main pathological cause of acute cardiovascular and cerebrovascular diseases, such as acute myocardial infarction and cerebral apoplexy. As an immune-mediated inflammatory disease, the pathogenesis of AS involves endothelial cell dysfunction, lipid accumulation, foam cell formation, vascular smooth muscle cell (VSMC) migration, and inflammatory factor infiltration. The nuclear receptor peroxisome proliferator-activated receptor gamma (PPARγ) plays an important role in lipid metabolism, inflammation, and apoptosis by antagonizing the Wnt/β-catenin pathway and regulating cholesterol efflux and inflammatory factors. Importantly, PPARγ-dependant fatty acid uptake is critical for metabolic programming. Activated PPARγ can exert an anti-atherosclerotic effect by inhibiting the expression of various inflammatory factors, improving endothelial cell function, and restraining the proliferation and migration of VSMCs. Regulatory T cells (Tregs) are the only subset of T lymphocytes that have a completely negative regulatory effect on the autoimmune response. They play a critical role in suppressing excessive immune responses and inflammatory reactions and widely affect AS-associated foam cell formation, plaque rupture, and other processes. Recent studies have shown that PPARγ activation promotes the recruitment of Tregs to reduce inflammation, thereby exerting its anti-atherosclerotic effect. In this review, we provide an overview of the anti-AS roles of PPARγ and Tregs by discussing their pathological mechanisms from the perspective of AS and immune-mediated inflammation, with a focus on basic research and clinical trials of their efficacies alone or in combination in inhibiting atherosclerotic inflammation. Additionally, we explore new ideas for AS treatment and plaque stabilization and establish a foundation for the development of natural PPARγ agonists with Treg recruitment capability.

Regulatory T Cells: A New Target of Chinese Medicine in Treatment of Atherosclerosis

Inflammation and immune disorders are integral to the occurrence and progression of atherosclerosis (AS). With the role of regulatory T cells (Tregs) in immune regulation attracting attention, it has been widely accepted that Treg decrease and dysfunction are involved in AS pathogenesis. Chinese medicine (CM) has the advantages of being dual-directional, multi-targeted, and having minimal side effects in immune regulation. The anti-atherosclerosis effects of CM via Treg modulation have been revealed in clinical and animal studies. Therefore, this article reviews existing research on Tregs, the relationship between Tregs and AS, and the progress of CM for treating and prevention of atherosclerotic cardio-cerebrovascular diseases by regulating Tregs. Although the underlying mechanisms remain to be elucidated, CM treatment targeting Treg cells might provide a promising and novel future approach for prevention and treatment of AS.

Targeting non-coding RNAs in unstable atherosclerotic plaques: Mechanism, regulation, possibilities, and limitations

Cardiovascular diseases (CVDs) caused by arteriosclerosis are the leading cause of death and disability worldwide. In the late stages of atherosclerosis, the atherosclerotic plaque gradually expands in the blood vessels, resulting in vascular stenosis. When the unstable plaque ruptures and falls off, it blocks the vessel causing vascular thrombosis, leading to strokes, myocardial infarctions, and a series of other serious diseases that endanger people's lives. Therefore, regulating plaque stability is the main means used to address the high mortality associated with CVDs. The progression of the atherosclerotic plaque is a complex integration of vascular cell apoptosis, lipid metabolism disorders, inflammatory cell infiltration, vascular smooth muscle cell migration, and neovascular infiltration. More recently, emerging evidence has demonstrated that non-coding RNAs (ncRNAs) play a significant role in regulating the pathophysiological process of atherosclerotic plaque formation by affecting the biological functions of the vasculature and its associated cells. The purpose of this paper is to comprehensively review the regulatory mechanisms involved in the susceptibility of atherosclerotic plaque rupture, discuss the limitations of current approaches to treat plaque instability, and highlight the potential clinical value of ncRNAs as novel diagnostic biomarkers and potential therapeutic strategies to improve plaque stability and reduce the risk of major cardiovascular events.

Urinary Proteomics Identifying Novel Biomarkers for the Diagnosis and Phenotyping of Carotid Artery Stenosis

Background: Carotid artery stenosis (CAS) is caused by the formation of atherosclerotic plaques inside the arterial wall and accounts for 20–30% of all strokes. The development of an early, noninvasive diagnostic method and the identification of high-risk patients for ischemic stroke is essential to the management of CAS in clinical practice.

Methods: We used the data-independent acquisition (DIA) technique to conduct a urinary proteomic study in patients with CAS and healthy controls. We identified the potential diagnosis and risk stratification biomarkers of CAS. And Ingenuity pathway analysis was used for functional annotation of differentially expressed proteins (DEPs). Furthermore, receiver operating characteristic (ROC) analysis was performed to evaluate the diagnostic values of DEPs.

Results: A total of 194 DEPs were identified between CAS patients and healthy controls by DIA quantification. The bioinformatics analysis showed that these DEPs were correlated with the pathogenesis of CAS. We further identified 32 DEPs in symptomatic CAS compared to asymptomatic CAS, and biological function analysis revealed that these proteins are mainly related to immune/inflammatory pathways. Finally, a biomarker panel of six proteins (ACP2, PLD3, HLA-C, GGH, CALML3, and IL2RB) exhibited potential diagnostic value in CAS and good discriminative power for differentiating symptomatic and asymptomatic CAS with high sensitivity and specificity.

Conclusions: Our study identified novel potential urinary biomarkers for noninvasive early screening and risk stratification of CAS.

Adoptive transfer of CX3CR1 transduced-T regulatory cells improves homing to the atherosclerotic plaques and dampens atherosclerosis progression

AIM

Loss of immunosuppressive response supports inflammation during atherosclerosis. We tested whether adoptive cell therapy (ACT) with Tregulatory cells (Tregs), engineered to selectively migrate in the atherosclerotic plaque, would dampen the immune-inflammatory response in the arterial wall in animal models of familial hypercholesterolaemia (FH).

METHODS AND RESULTS

FH patients presented a decreased Treg suppressive function associated to an increased inflammatory burden. A similar phenotype was observed in Ldlr -/- mice accompanied by a selective increased expression of the chemokine CX3CL1 in the aorta but not in other districts (lymph nodes, spleen, and liver). Treg overexpressing CX3CR1 were thus generated (CX3CR1+-Tregs) to drive Tregs selectively to the plaque. CX3CR1+-Tregs were injected (i.v.) in Ldlr -/- fed high-cholesterol diet (western type diet, WTD) for 8 weeks. CX3CR1+-Tregs were detected in the aorta, but not in other tissues, of Ldlr -/- mice 24 h after ACT, corroborating the efficacy of this approach. After 4 additional weeks of WTD, ACT with CX3CR1+-Tregs resulted in reduced plaque progression and lipid deposition, ameliorated plaque stability by increasing collagen and smooth muscle cells content, while decreasing the number of pro-inflammatory macrophages. Shotgun proteomics of the aorta showed a metabolic rewiring in CX3CR1+-Tregs treated Ldlr -/- mice compared to controls that was associated with the improvement of inflammation-resolving pathways and disease progression.

CONCLUSION

ACT with vasculotropic Tregs appears as a promising strategy to selectively target immune activation in the atherosclerotic plaque.

Antiretroviral therapy-treated HIV-infected adults with coronary artery disease are characterized by a distinctive regulatory T-cell signature

BACKGROUND

Despite the success of antiretroviral therapy (ART) to control viral replication, people living with HIV (PWH) have high levels of chronic systemic inflammation and immune dysregulation which drives accelerated co-morbidities including coronary artery disease (CAD). Regulatory T cells (Tregs) and ectonucleotidases CD39/CD73 are known to be athero-protective via their immunosuppressive and anti-inflammatory functions.

DESIGN

We assessed the dynamics of Treg subsets in ART-treated PWH with or without CAD vs. HIV-uninfected individuals.

METHODS

Blood specimens were obtained from 142 participants including ART-treated HIV-infected adults with (n = 43) or without CAD (n = 41), as well as HIV-uninfected controls with (n = 31) or without CAD (n = 27). CAD was determined by the presence of atherosclerotic features on computed tomography angiography of the coronary arteries performed on all study participants. Treg subsets frequencies were assessed by flow cytometry.

RESULTS

Regardless of statin treatment or ART regimen, HIV+CAD+ individuals had the highest total Treg frequencies and increased thymic generation and output of Tregs (Helios/CD31 expression), while athero-protective CD39+/CD73+ Tregs were significantly depleted in this group. Tregs from PWH had higher expression of CCR6/CXCR3 than uninfected individuals regardless of CAD, while in HIV+CAD+ individuals Tregs expressed the highest levels of CCR4, which limits their maintenance. The lowest levels of CD4+ and CD8+ T-cell immune activation has been observed in HIV+CAD+ within study groups.

CONCLUSION

ART-treated PWH with diagnosed CAD are characterized by profound alterations in populations of anti-inflammatory and athero-protective Treg subsets. These changes may contribute to atherosclerotic plaque formation and progression during chronic HIV infection in the ART era.

Regulatory T Cell-Related Gene Biomarkers in the Deterioration of Atherosclerosis

Background: Regulatory T cells (Tregs) have shown to be protective against the development of atherosclerosis, a major pathological cause for cardiovascular events. Here, we aim to explore the roles of Tregs-related genes in atherosclerosis deterioration. Methods and Results: We downloaded the gene expression profile of 29 atherosclerotic samples from the Gene Expression Omnibus database with an accession number of GSE28829. The abundance of Tregs estimated by the CIBERSORT algorithm was negatively correlated with the atherosclerotic stage. Using the limma test and correlation analysis, a total of 159 differentially expressed Tregs-related genes (DETregRGs) between early and advanced atherosclerotic plaques were documented. Functional annotation analysis using the DAVID tool indicated that the DETregRGs were mainly enriched in inflammatory responses, immune-related mechanisms, and pathways such as complement and coagulation cascades, platelet activation, leukocyte trans-endothelial migration, vascular smooth muscle contraction, and so on. A protein-protein interaction network of the DETregRGs was then constructed, and five hub genes (PTPRC, C3AR1, CD53, TLR2, and CCR1) were derived from the network with node degrees ≥20. The expression patterns of these hub DETregRGs were further validated in several independent datasets. Finally, a single sample scoring method was used to build a gene signature for the five DETregRGs, which could distinguish patients with myocardial infarction from those with stable coronary disease. Conclusion: The results of this study will improve our understanding about the Tregs-associated molecular mechanisms in the progression of atherosclerosis and facilitate the discovery of novel biomarkers for acute cardiovascular events.

CD4+CD25+ Regulatory T Cells in Intracranial Thrombi Are Inversely Correlated with Hemorrhagic Transformation after Thrombectomy: A Clinical-Immunohistochemical Analysis of Acute Ischemic Stroke

Mechanical thrombectomy is not only effective for managing patients with acute ischemic stroke (AIS), but it also enables a valuable histological analysis of thrombi. Previous studies indicated that regulatory T cells (Treg) adoptive transfer might alleviate the hemorrhagic transformation. However, whether Treg in intracranial thrombi correlates with hemorrhagic transformation after mechanical thrombectomy remains unclear. This study mainly analyzed the colocation of Treg markers in serial thrombus sections stained serially for CD4 and CD25 in groups of hemorrhagic or nonhemorrhagic transformation. Second, to investigate whether these immunohistochemical parameters could provide any additional information beyond hemorrhagic transformation, we compared the overlap between Treg markers among other groups, such as functional outcomes, stroke subtypes, and gender. Our results showed that the number of CD4⁺CD25⁺ Treg cells was lower in the hemorrhagic transformation thrombi than in the nonhemorrhagic group (p < 0.001) but there were no significant differences otherwise. The present finding of CD4⁺CD25⁺ Treg cell reductions in thrombi associated with hemorrhagic transformation provides the histological evidence supporting that thromboinflammation might involve in the pathological process of an acute stroke after mechanical thrombectomy.

Diet-induced dyslipidemia induces metabolic and migratory adaptations in regulatory T cells

AIMS

A hallmark of advanced atherosclerosis is inadequate immunosuppression by regulatory T (Treg) cells inside atherosclerotic lesions. Dyslipidemia has been suggested to alter Treg cell migration by affecting the expression of specific membrane proteins, thereby decreasing Treg cell migration towards atherosclerotic lesions. Besides membrane proteins, cellular metabolism has been shown to be a crucial factor in Treg cell migration. We aimed to determine whether dyslipidemia contributes to altered migration of Treg cells, in part, by affecting cellular metabolism.

METHODS AND RESULTS

Dyslipidemia was induced by feeding Ldlr-/- mice a western-type diet for 16-20 weeks and intrinsic changes in Treg cells affecting their migration and metabolism were examined. Dyslipidemia was associated with altered mTORC2 signalling in Treg cells, decreased expression of membrane proteins involved in migration, including CD62L, CCR7, and S1Pr1, and decreased Treg cell migration towards lymph nodes. Furthermore, we discovered that diet-induced dyslipidemia inhibited mTORC1 signalling, induced PPARδ activation and increased fatty acid (FA) oxidation in Treg cells. Moreover, mass-spectrometry analysis of serum from Ldlr-/- mice with normolipidemia or dyslipidemia showed increases in multiple PPARδ ligands during dyslipidemia. Treatment with a synthetic PPARδ agonist increased the migratory capacity of Treg cells in vitro and in vivo in an FA oxidation-dependent manner. Furthermore, diet-induced dyslipidemia actually enhanced Treg cell migration into the inflamed peritoneum and into atherosclerotic lesions in vitro.

CONCLUSION

Altogether, our findings implicate that dyslipidemia does not contribute to atherosclerosis by impairing Treg cell migration as dyslipidemia associated with an effector-like migratory phenotype in Treg cells.

Regulatory T Cell-Enhancing Therapies to Treat Atherosclerosis

Experimental studies have provided strong evidence that chronic inflammation triggered by the sub-endothelial accumulation of cholesterol-rich lipoproteins in arteries is essential in the initiation and progression of atherosclerosis. Recent clinical trials highlighting the efficacy of anti-inflammatory therapies in coronary patients have confirmed that this is also true in humans Monocytes/macrophages are central cells in the atherosclerotic process, but adaptive immunity, through B and T lymphocytes, as well as dendritic cells, also modulates the progression of the disease. Analysis of the role of different T cell subpopulations in murine models of atherosclerosis identified effector Th1 cells as proatherogenic, whereas regulatory T cells (Tregs) have been shown to protect against atherosclerosis. For these reasons, better understanding of how Tregs influence the atherosclerotic process is believed to provide novel Treg-targeted therapies to combat atherosclerosis. This review article summarizes current knowledge about the role of Tregs in atherosclerosis and discusses ways to enhance their function as novel immunomodulatory therapeutic approaches against cardiovascular disease.

Adaptive Immune Responses in Human Atherosclerosis

Atherosclerosis is a chronic inflammatory disease that is initiated by the deposition and accumulation of low-density lipoproteins in the artery wall. In this review, we will discuss the role of T- and B-cells in human plaques at different stages of atherosclerosis and the utility of profiling circulating immune cells to monitor atherosclerosis progression. Evidence supports a proatherogenic role for intraplaque T helper type 1 (Th1) cells, CD4⁺CD28^null T-cells, and natural killer T-cells, whereas Th2 cells and regulatory T-cells (Treg) have an atheroprotective role. Several studies indicate that intraplaque T-cells are activated upon recognition of endogenous antigens including heat shock protein 60 and oxidized low-density lipoprotein, but antigens derived from pathogens can also trigger T-cell proliferation and cytokine production. Future studies are needed to assess whether circulating cellular biomarkers can improve identification of vulnerable lesions so that effective intervention can be implemented before clinical manifestations are apparent.

Yeast microcapsule-mediated oral delivery of IL-1β shRNA for post-traumatic osteoarthritis therapy

Post-traumatic osteoarthritis is a prevalent debilitating joint disease. However, there is no FDA-approved disease-modifying osteoarthritis drug currently. Gene therapy can improve disease progression but lacks an effective delivery system. Here, we constructed an oral drug delivery system by non-virus-mediated interleukin-1β (IL-1β) short hairpin RNA (shRNA) and non-pathogenic yeast to evaluate its effect on osteoarthritis therapy. After recombinant IL-1β shRNA/yeast therapy, yeast microcapsule-mediated oral delivery of IL-1β shRNA greatly reduced the IL-1β expression in intestine macrophage, bone marrow macrophage, and articular cartilage, systematically regulate the inflammatory response. The degeneration of articular cartilage was significantly inhibited in the medial femoral condyle and medial tibial plateau of the knee joint. And the expression of osteoarthritis markers Col X and MMP13 was reduced in the knee joint. Thus, yeast microcapsule-mediated oral delivery of IL-1β shRNA may serve as a novel gene therapy strategy for treating joint degeneration through immunomodulation of the mononuclear phagocyte system from the intestine to subchondral bone marrow and ultimately preserving the articular cartilage joint.

An Injectable Hydrogel Platform for Sustained Delivery of Anti-inflammatory Nanocarriers and Induction of Regulatory T Cells in Atherosclerosis

Chronic unresolved vascular inflammation is a critical factor in the development of atherosclerosis. Cardiovascular immunotherapy has therefore become a recent focus for treatment, with the objective to develop approaches that can suppress excessive inflammatory responses by modulating specific immune cell populations. A benefit of such immunomodulatory strategies is that low dosage stimulation of key immune cell populations, like antigen presenting cells, can subsequently propagate strong proliferation and therapeutic responses from effector cells. We have previously demonstrated that intravenous injections of anti-inflammatory nanocarriers provided atheroprotection that was mediated by regulatory T cells (Tregs) upregulated in lymphoid organs and atherosclerotic lesions. Here, we demonstrate an injectable filamentous hydrogel depot (FM-depot) engineered for low dosage, sustained delivery of anti-inflammatory nanocarriers. The bioactive form of vitamin D (aVD; 1, 25-Dihydroxyvitamin D3), which inhibits pro-inflammatory transcription factor NF-κB via the intracellular nuclear hormone receptor vitamin D receptor (VDR), was stably loaded into poly(ethylene glycol)-block-poly(propylene sulfide) (PEG-b-PPS) filomicelles. These aVD-loaded filaments underwent morphological transitions to release monodisperse drug-loaded micelles upon oxidation. This cylinder-to-micelle transition was characterized in vitro by cryogenic transmission electron microscopy (CryoTEM) and small angle X-ray scattering (SAXS). Following crosslinking with multi-arm PEG for in situ gelation, aVD-loaded FM-depots maintained high levels of Foxp3⁺ Tregs in both lymphoid organs and atherosclerotic lesions for weeks following a single subcutaneous injection into ApoE^-/- mice. FM-depots therefore present a customizable delivery platform to both develop and test nanomedicine-based approaches for anti-inflammatory cardiovascular immunotherapy.

Regulatory T Cells License Macrophage Pro-Resolving Functions During Atherosclerosis Regression

RATIONALE

Regression of atherosclerosis is an important clinical goal; however, the pathways that mediate the resolution of atherosclerotic inflammation and reversal of plaques are poorly understood. Regulatory T cells (Tregs) have been shown to be atheroprotective, yet the numbers of these immunosuppressive cells decrease with disease progression, and whether they contribute to atherosclerosis regression is not known.

OBJECTIVE

We investigated the roles of Tregs in the resolution of atherosclerotic inflammation, tissue remodeling, and plaque contraction during atherosclerosis regression.

METHODS AND RESULTS

Using multiple independent mouse models of atherosclerosis regression, we demonstrate that an increase in plaque Tregs is a common signature of regressing plaques. Single-cell RNA-sequencing of plaque immune cells revealed that unlike Tregs from progressing plaques that expressed markers of natural Tregs derived from the thymus, Tregs in regressing plaques lacked Nrp1 expression, suggesting that they are induced in the periphery during lipid-lowering therapy. To test whether Tregs are required for resolution of atherosclerotic inflammation and plaque regression, Tregs were depleted using CD25 monoclonal antibody in atherosclerotic mice during apolipoprotein B antisense oligonucleotide-mediated lipid lowering. Morphometric analyses revealed that Treg depletion blocked plaque remodeling and contraction, and impaired hallmarks of inflammation resolution, including dampening of the T helper 1 response, alternative activation of macrophages, efferocytosis, and upregulation of specialized proresolving lipid mediators.

CONCLUSIONS

Our data establish essential roles for Tregs in resolving atherosclerotic cardiovascular disease and provide mechanistic insight into the pathways governing plaque remodeling and regression of disease.

Sex as a Biological Variable in Atherosclerosis

Atherosclerosis is a chronic inflammatory vascular disease and the predominant cause of heart attack and ischemic stroke. Despite the well-known sexual dimorphism in the incidence and complications of atherosclerosis, there are relatively limited data in the clinical and preclinical literature to rigorously address mechanisms underlying sex as a biological variable in atherosclerosis. In multiple histological and imaging studies, overall plaque burden and markers of inflammation appear to be greater in men than women and are predictive of cardiovascular events. However, while younger women are relatively protected from cardiovascular disease, by the seventh decade, the incidence of myocardial infarction in women ultimately surpasses that of men, suggesting an interaction between sex and age. Most preclinical studies in animal atherosclerosis models do not examine both sexes, and even in those that do, well-powered direct statistical comparisons for sex as an independent variable remain rare. This article reviews the available data. Overall, male animals appear to have more inflamed yet smaller plaques compared to female animals. Plaque inflammation is often used as a surrogate end point for plaque vulnerability in animals. The available data support the notion that rather than plaque size, plaque inflammation may be more relevant in assessing sex-specific mechanisms since the findings correlate with the sex difference in ischemic events and mortality and thus may be more reflective of the human condition. Overall, the number of preclinical studies directly comparing plaque inflammation between the sexes is extremely limited relative to the vast literature exploring atherosclerosis mechanisms. Failure to include both sexes and to address age in mechanistic atherosclerosis studies are missed opportunities to uncover underlying sex-specific mechanisms. Understanding the mechanisms driving sex as a biological variable in atherosclerotic disease is critical to future precision medicine strategies to mitigate what is still the leading cause of death of men and women worldwide.

Sequential Surgical Procedures in Vascular Surgery Patients Are Associated With Perioperative Adverse Cardiac Events

Patients at elevated cardiovascular risk are prone to perioperative cardiovascular complications, like myocardial injury after non-cardiac surgery (MINS). We have demonstrated in a mouse model of atherosclerosis that perioperative stress leads to an increase in plaque volume and higher plaque vulnerability. Regulatory T cells (Tregs) play a pivotal role in development and destabilization of atherosclerotic plaques. For this exploratory post-hoc analysis we identified 40 patients recruited into a prospective perioperative biomarker study, who within the inclusion period underwent sequential open vascular surgery. On the basis of protein markers measured in the biomarker study, we evaluated the perioperative inflammatory response in patients' plasma before and after index surgery as well as before and after a second surgical procedure. We also analyzed available immunohistochemistry samples to describe plaque vulnerability in patients who underwent bilateral carotid endarterectomy (CEA) in two subsequent surgical procedures. Finally, we assessed if MINS was associated with sequential surgery. The inflammatory response of both surgeries was characterized by postoperative increases of interleukin-6,−10, Pentraxin 3 and C-reactive protein with no clear-cut difference between the two time points of surgery. Plaques from CEA extracted during the second surgery contained less Tregs, as measured by Foxp3 staining, than plaques from the first intervention. The 2nd surgical procedure was associated with MINS. In conclusion, we provide descriptive evidence that sequential surgical procedures involve repeat inflammation, and we hypothesize that elevated rates of cardiovascular complications after the second procedure could be related to reduced levels of intraplaque Tregs, a finding that deserves confirmatory testing and mechanistic exploration in future populations.

Immune cells in carotid artery plaques: what can we learn from endarterectomy specimens?

INTRODUCTION

Endarterectomy specimens represent a unique opportunity to study atherosclerosis. This review aims to summarize the recent knowledge of atherogenesis from studies characterizing a cellular composition of carotid endarterectomy specimens.

EVIDENCE ACQUISITION

A non-systematic literature review was carried out to summarize recent knowledge regarding ex vivo analysis of carotid artery plaque composition. Upon evaluation of their relevance, and elaborate forward and backward search, 95 articles were included in the review.

EVIDENCE SYNTHESIS

Despite the significant advancement of in vivo imaging techniques, the stroke prediction based on carotid artery plaque morphology is not reliable. Besides analyses of plaque morphology, present studies focus on precise characterization of the different immune cell types and elucidation of their role in plaque development. Plaque content analyses revealed the presence of various immune cells in carotid artery plaques. Presence of different immune cells subpopulations can be connected to some undesirable changes in plaque stability.

CONCLUSIONS

Since the destabilization of the atherosclerotic plaque is a multifactorial process, a combination of various methods should be used to characterize the unstable plaques more accurately. In this context, studies characterizing plaque content from a cellular point of view could elucidate some processes underlying the plaque progression. Together with morphological evaluation, these analyses could enable more precise assessment of plaque stability.

Low Tregs: A targetable risk factor for life-threatening cardiovascular complications after major noncardiac surgery

Discussion on Tregs that have anti-inflammatory and anti-atherogenic properties as an ideal therapeutic target to reduce fatal cardiovascular deaths following major noncardiac surgery.

Frontline Science: Low regulatory T cells predict perioperative major adverse cardiovascular and cerebrovascular events after noncardiac surgery

Immune cells drive atherosclerotic lesion progression and plaque destabilization. Coronary heart disease patients undergoing noncardiac surgery are at risk for perioperative major adverse cardiac and cerebrovascular events (MACCE). It is unclear whether differential leukocyte subpopulations contribute to perioperative MACCE and thereby could aid identification of patients prone to perioperative cardiovascular events. First, we performed a hypothesis-generating post hoc analysis of the LeukoCAPE-1 study (n = 38). We analyzed preoperative counts of 6 leukocyte subpopulations in coronary heart disease patients for association with MACCE (composite of cardiac death, myocardial infarction, myocardial ischemia, myocardial injury after noncardiac surgery, thromboembolic stroke) within 30 d after surgery. Regulatory T cells (Tregs) were the only leukocyte subgroup associated with MACCE. We found reduced Tregs in patients experiencing MACCE versus no-MACCE (0.02 [0.01; 0.03] vs. 0.04 [0.03; 0.05] Tregs nl^-1 , P = 0.002). Using Youden index, we derived the optimal threshold value for association with MACCE to be 0.027 Tregs nl^-1 . Subsequently, we recruited 233 coronary heart disease patients for the prospective, observational LeukoCAPE-2 study and independently validated this Treg cutoff for prediction of MACCE within 30 d after noncardiac surgery. After multivariate logistic regression, Tregs < 0.027 cells nl^-1 remained an independent predictor for MACCE (OR = 2.54 [1.22; 5.23], P = 0.012). Tregs improved risk discrimination of the revised cardiac risk index based on ΔAUC (area under the curve; ΔAUC = 0.09, P = 0.02), NRI (0.26), and IDI (0.06). Preoperative Treg levels below 0.027 cells nl^-1 predicted perioperative MACCE and can be measured to increase accuracy of established preoperative cardiac risk stratification in coronary heart disease patients undergoing noncardiac surgery.

Notch Signaling Regulates Immune Responses in Atherosclerosis

Atherosclerosis is a chronic autoimmune inflammatory disease that can cause coronary artery disease, stroke, peripheral artery disease, depending on which arteries are affected. At the beginning of atherosclerosis plasma lipoproteins accumulate in the sub-endothelial space. In response, monocytes migrate from the circulation through the endothelium into the intima where they differentiate into macrophages. These early events trigger a complex immune response that eventually involves many cellular subtypes of both innate and adaptive immunity. The Notch signaling pathway is an evolutionary conserved cell signaling system that mediates cell-to-cell communication. Recent studies have revealed that Notch modulate atherosclerosis by controlling macrophages polarization into M1 or M2 subtypes. Furthermore, it is known that Notch signaling controls differentiation and activity of T-helper and cytotoxic T-cells in inflammatory diseases. In this review, we will discuss the role of Notch in modulating immunity in the context of atherosclerosis and whether targeting Notch may represent a therapeutic strategy.