Circulating CD4+CD25hiCD127lo regulatory T-Cell levels do not reflect the extent or severity of carotid and coronary atherosclerosis

Subpopulations of regulatory T cells are associated with subclinical atherosclerotic plaques, levels of LDL, and cardiorespiratory fitness in the elderly

BACKGROUND

Atherosclerosis forms the pathological basis for the development of cardiovascular disease. Since pathological processes initially develop without clinically relevant symptoms, the identification of early markers in the subclinical stage plays an important role for initiating early interventions. There is evidence that regulatory T cells (Tregs) are involved in the development of atherosclerosis. Therefore, the present study aimed to identify and investigate associations with Tregs and their subsets in a cohort of healthy elderly individuals with and without subclinical atherosclerotic plaques (SAP). In addition, various lifestyle and risk factors, such as cardiorespiratory fitness, were investigated as associated signatures.

METHODS

A cross-sectional study was performed in 79 participants (male: n = 50; age = 63.6 ± 3.7 years; body mass index = 24.9 ± 3.1 kg/m²; mean ± SD) who had no previous diagnosis of chronic disease and were not taking medication. Ultrasound of the carotids to identify SAP, cardiovascular function measurement for vascular assessment and a cardiorespiratory fitness test to determine peak oxygen uptake were performed. Additionally, tests were conducted to assess blood lipids and determine glucose levels. Immunophenotyping of Tregs and their subtypes (resting (rTregs) and effector/memory (mTregs)) was performed by 8-chanel flow cytometry. Participants were categorized according to atherosclerotic plaque status. Linear and logistic regression models were used to analyze associations between parameters.

RESULTS

SAP was detected in a total of 29 participants. The participants with plaque were older (64.8 ± 3.6 years vs. 62.9 ± 3.5 years) and had higher peripheral systolic blood pressure (133.8 ± 14.7 mmHg vs. 125.8 ± 10.9 mmHg). The participants with SAP were characterized by a lower percentage of rTregs (28.8% ± 10.7% vs. 34.6% ± 10.7%) and a higher percentage of mTregs (40.3% ± 14.7% vs. 30.0% ± 11.9%). Multiple logistic regression identified age (odds ratio (OR) = 1.20 (95% confidence interval (95%CI): 1.01-1.42)) and mTregs (OR = 1.05 (95%CI: 1.02-1.10)) as independent risk factors for SAP. Stepwise linear regression could reveal an association of peak oxygen uptake (β = 0.441), low-density lipoprotein (LDL) (β = -0.096), and SAP (β = 6.733) with mTregs and LDL (β = 0.104) with rTregs.

CONCLUSION

While at an early stage of SAP, the total proportion of Tregs gives no indication of vascular changes, this is indicated by a shift in the Treg subgroups. Factors such as serum LDL or cardiopulmonary fitness may be associated with this shift and may also be additional diagnostic indicators. This could be used to initiate lifestyle-based preventive measures at an early stage, which may have a protective effect against disease progression.

Dysfunctional regulatory T cell: May be an obstacle to immunotherapy in cardiovascular diseases

Inflammatory responses are linked to cardiovascular diseases (CVDs) in various forms. Tregs, members of CD4+ T cells, play important roles in regulating immune system and suppressing inflammatory response, thus contributing to maintaining immune homeostasis. However, Tregs exert their powerful suppressive function relying on the stable phenotype and function. The stability of Tregs primarily depends on the FOXP3 (Forkhead box P3) expression and epigenetic regulation. Although Tregs are quite stable under physiological conditions, prolonged exposure to inflammatory cues, Tregs may lose suppressive function and require proinflammatory phenotype, namely plastic Tregs or ex-Tregs. There are extensive researches have established the beneficial role of Tregs in CVDs. Nevertheless, the potential risks of dysfunctional Tregs lack deep research. Anti-inflammatory and immunological modulation have been hotspots in the treatment of CVDs. Tregs are appealing because of their crucial role in resolving inflammation and promoting tissue repair. If alleviating inflammatory response through modulating Tregs could be a new therapeutic strategy for CVDs, the next step to consider is how to prevent the formation of dysfunctional Tregs or reverse detrimental Tregs to normal phenotype.

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.

Nomogram for predicting the prognosis of metastatic colorectal cancer patients treated with anti-PD1 therapy based on serum lipids analysis

BACKGROUND

Serum lipids have been identified to be used as prognostic biomarkers in several types of cancer. The primary objective of this study was to evaluate the prognostic value of serum lipids in metastatic colorectal cancer (mCRC) patients received anti-PD-1 therapy.

METHODS

Pretreatment and the alteration of serum lipids, including apolipoprotein B (ApoB), apolipoprotein A-I (ApoA-I), cholesterol (CHO), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C) and triglyceride (TG) after 2 courses of anti-PD1 therapy, were collected. Kaplan-Meier survival and cox regression analysis were performed to identify the prognostic values on overall survival (OS). Finally, those significant predictors from multivariate analysis were used to construct a nomogram for the prediction of prognosis.

RESULTS

Baseline ApoB, CHO, HDL-C, LDL-C and early changes of ApoB, ApoA-I, HDL-C were statistically significant in the ROC analysis, showing good discriminatory ability in terms of OS. In multivariate analysis, treatment lines, lung metastasis, baseline HDL-C (low vs. high, HR, 6.30; 95% CI 1.82-21.80; P = 0.004) and early changes in HDL-C (reduction vs. elevation, HR, 4.59, 95% CI 1.20-17.63; P = 0.026) independently predicted OS. The area under the time-dependent ROC curve at 1 year, 2 years and 3 years consistently demonstrated the satisfactory accuracy and predictive value of the nomogram (AUC: 0.88, 0.85, 0.84).

CONCLUSION

Overall, high level at baseline and an early elevation of HDL-C are correlated with better outcomes in mCRC patients treated with anti-PD1 therapy. The constructed nomogram indicated that the factors are strong predictive markers for response and prognosis to anti-PD-1 therapy in metastatic colorectal cancer.

Cumulative physiological stress is associated with age-related changes to peripheral T lymphocyte subsets in healthy humans

BACKGROUND

Progressive age-associated change in frequencies and functional capacities of immune cells is known as immunosenescence. Despite data linking chronic environmental, physiological, and psychosocial stressors with accelerated aging, how stress contributes to immunosenesence is not well characterized.

OBJECTIVE

To help delineate the contribution of cumulative physiological stress on immunosensence we assessed relationships between a composite measurement of cumulative physiological stress, reflecting the functioning of the hypothalamic-pituitary-adrenal axis, sympathetic nervous system, cardiovascular system, and metabolic processes, and lymphocyte changes typically affiliated with aging in a cohort of healthy volunteers ranging from 18 to 66 y.

RESULTS

Physiological stress load positively correlated with subject age in the study cohort and was significantly higher in adults 50-66 y compared to adults 18-33 y and 34-49 y. Using physiological stress load, we identified a significant age-dependent association between stress load and frequencies of circulating regulatory T lymphocytes (Tregs). Frequencies were higher in younger participants, but only in participants exhibiting low physiological stress load. As stress load increased, frequencies of Tregs decreased in young participants but were unchanged with increasing stress load in middle and older age individuals. Follow-up analysis of stress load components indicated lower circulating DHEA-S and higher urinary norepinephrine as the primary contributors to the effects of total stress load on Tregs. In addition, we identified age-independent inverse associations between stress load and frequencies of naïve Tregs and naïve CD4 T cells and positive associations between stress load and frequencies of memory Tregs and memory CD4 T cells. These associations were primarily driven by stress load components waist circumference, systolic and diastolic blood pressure, CRP, and HbA1c. In summary, our study results suggest that, in younger people, physiological stress load may diminish regulatory T cell frequencies to levels seen in older persons. Furthermore, independent of age, stress load may contribute to contraction of the naïve Treg pool and accumulation of memory Treg cells.

CLINICAL TRIAL

Registered on ClincialTrials.gov (Identifier: NCT02367287).

Low-dose interleukin 2 for the reduction of vascular inflammation in acute coronary syndromes (IVORY): protocol and study rationale for a randomised, double-blind, placebo-controlled, phase II clinical trial

INTRODUCTION

Inflammation plays a critical role in the pathogenesis of atherosclerosis, the leading cause of ischaemic heart disease (IHD). Studies in preclinical models have demonstrated that an increase in regulatory T cells (Tregs), which have a potent immune modulatory action, led to a regression of atherosclerosis. The Low-dose InterLeukin 2 (IL-2) in patients with stable ischaemic heart disease and Acute Coronary Syndromes (LILACS) study, established the safety of low-dose IL-2 and its biological efficacy in IHD. The IVORY trial is designed to assess the effects of low-dose IL-2 on vascular inflammation in patients with acute coronary syndromes (ACS).

METHODS AND ANALYSIS

In this study, we hypothesise that low-dose IL-2 will reduce vascular inflammation in patients presenting with ACS. This is a double-blind, randomised, placebo-controlled, phase II clinical trial. Patients will be recruited across two centres, a district general hospital and a tertiary cardiac centre in Cambridge, UK. Sixty patients with ACS (unstable angina, non-ST elevation myocardial infarction or ST elevation myocardial infarction) with high-sensitivity C reactive protein (hsCRP) levels >2 mg/L will be randomised to receive either 1.5×10⁶ IU of low-dose IL-2 or placebo (1:1). Dosing will commence within 14 days of admission. Dosing will comprise of an induction and a maintenance phase. 2-Deoxy-2-[fluorine-18] fluoro-D-glucose (¹⁸F-FDG) positron emission tomography/CT (PET/CT) scans will be performed before and after dosing. The primary endpoint is the change in mean maximum target to background ratios (TBR_max) in the index vessel between baseline and follow-up scans. Changes in circulating T-cell subsets will be measured as secondary endpoints of the study. The safety and tolerability of extended dosing with low-dose IL-2 in patients with ACS will be evaluated throughout the study.

ETHICS AND DISSEMINATION

The Health Research Authority and Health and Care Research Wales, UK (19/YH/0171), approved the study. Written informed consent is required to participate in the trial. The results will be reported through peer-reviewed journals and conference presentations.

TRIAL REGISTRATION NUMBER

NCT04241601.

Atherosclerosis and multi-organ-associated pathologies

Atherosclerosis is a chronic inflammatory disease of the vascular system that is characterized by the deposition of modified lipoproteins, accumulation of immune cells, and formation of fibrous tissue within the vessel wall. The disease occurs in vessels throughout the body and affects the functions of almost all organs including the lymphoid system, bone marrow, heart, brain, pancreas, adipose tissue, liver, kidneys, and gastrointestinal tract. Atherosclerosis and associated factors influence these tissues via the modulation of local vascular functions, induction of cholesterol-associated pathologies, and regulation of local immune responses. In this review, we discuss how atherosclerosis interferers with functions of different organs via several common pathways and how the disturbance of immunity in atherosclerosis can result in disease-provoking dysfunctions in multiple tissues. Our growing appreciation of the implication of atherosclerosis and associated microenvironmental conditions in the multi-organ pathology promises to influence our understanding of CVD-associated disease pathologies and to provide new therapeutic opportunities.

Regulatory T-Cell Response to Low-Dose Interleukin-2 in Ischemic Heart Disease

BACKGROUND: Atherosclerosis is a chronic inflammatory disease of the artery wall. Regulatory T cells (Tregs) limit inflammation and promote tissue healing. Low doses of interleukin (IL)-2 have the potential to increase Tregs, but its use is contraindicated for patients with ischemic heart disease. METHODS: In this randomized, double-blind, placebo-controlled, dose-escalation trial, we tested low-dose subcutaneous aldesleukin (recombinant IL-2), given once daily for 5 consecutive days. In study part A, the primary end point was safety, and patients with stable ischemic heart disease were randomly assigned to receive placebo or to one of five dose groups (range, 0.3 to 3.0 × 106 IU daily). In study part B, patients with acute non-ST elevation myocardial infarction or unstable angina were randomly assigned to receive placebo or to one of two dose groups (1.5 and 2.5 × 106 IU daily). The coprimary end points were safety and the dose required to increase circulating Tregs by 75%. Single-cell RNA-sequencing of circulating immune cells was used to provide a mechanistic assessment of the effects of aldesleukin. RESULTS: Forty-four patients were randomly assigned to either study part A (n=26) or part B (n=18). In total, 3 patients withdrew before dosing, 27 received active treatment, and 14 received placebo. The majority of adverse events were mild. Two serious adverse events occurred, with one occurring after drug administration. In parts A and B, there was a dose-dependent increase in Tregs. In part B, the estimated dose to achieve a 75% increase in Tregs was 1.46 × 106 IU (95% confidence interval, 1.06 to 1.87). Single-cell RNA-sequencing demonstrated the engagement of distinct pathways and cell–cell interactions. CONCLUSIONS: In this phase 1b/2a study, low-dose IL-2 expanded Tregs without adverse events of major concern. Larger trials are needed to confirm the safety and to further evaluate the efficacy of low-dose IL-2 as an anti-inflammatory therapy for patients with ischemic heart disease. (Funded by the Medical Research Council, the British Heart Foundation, and others; ClinicalTrials.gov number, NCT03113773)

Recent Advances on the Role and Therapeutic Potential of Regulatory T Cells in Atherosclerosis

Atherosclerotic diseases, including ischemic heart disease and stroke, are a main cause of mortality worldwide. Chronic vascular inflammation via immune dysregulation is critically involved in the pathogenesis of atherosclerosis. Accumulating evidence suggests that regulatory T cells (Tregs), responsible for maintaining immunological tolerance and suppressing excessive immune responses, play an important role in preventing the development and progression of atherosclerosis through the regulation of pathogenic immunoinflammatory responses. Several strategies to prevent and treat atherosclerosis through the promotion of regulatory immune responses have been developed, and could be clinically applied for the treatment of atherosclerotic cardiovascular disease. In this review, we summarize recent advances in our understanding of the protective role of Tregs in atherosclerosis and discuss attractive approaches to treat atherosclerotic disease by augmenting regulatory immune responses.

The Association of Circulating CD14++CD16+ Monocytes, Natural Killer Cells and Regulatory T Cells Subpopulations With Phenotypes of Cardiovascular Disease in a Cohort of Peritoneal Dialysis Patients

The altered expression of immune cells including monocyte subsets, natural killer (NK) cells and CD4+CD25+ regulatory T cells (Tregs) in end-stage kidney disease, affect the modulation of inflammation and immunity with significant clinical implications. The aim of this study was to investigate the profile of specific immune cells subpopulations and their correlations with phenotypes of established cardiovascular disease (CVD), including coronary artery disease (CAD) and heart failure (HF) in peritoneal dialysis (PD) patients.

Materials and Methods: 29 stable PD patients and 13 healthy volunteers were enrolled. Demographic, laboratory, bioimpedance measurements, lung ultrasound and echocardiography data were collected. The peripheral blood immune cell subsets analysis was performed using flow cytometry.

Results: PD patients compared to normal controls had lower total lymphocytes (22.3 ± 6.28 vs. 31.3 ± 5.54%, p = <0.001) and B-lymphocytes (6.39 ± 3.75 vs. 9.72 ± 3.63%, p = 0.01) as well as higher CD14++CD16+ monocytes numbers (9.28 ± 6.36 vs. 4.75 ± 2.75%, p = 0.0002). PD patients with prevalent CAD had NK cells levels elevated above median values (85.7 vs. 40.9%, p = 0.04) and lower B cells counts (3.85 ± 2.46 vs. 7.2 ± 3.77%, p = 0.03). Patients with increased NK cells (>15.4%) had 3.8 times higher risk of CAD comparing with patients with lower NK cell levels (95% CI, 1.86 – 77.87; p = 0.034). B cells were inversely associated with the presence of CAD (increase of B-lymphocyte by 1% was associated with 30% less risk for presence of CAD (95% CI, −0.71 – 0.01; p = 0.05). Overhydrated patients had lower lymphocytes counts (18.3 ± 4.29% vs. 24.7 ± 6.18%, p = 0.006) and increased NK cells [20.5% (14.3, 23.6) vs. 13.21% (6.23, 19.2), p = 0.04)]. In multiple logistic regression analysis the CRP (OR 1.43; 95% CI, 1.00 – 2.05; p = 0.04)] and lymphocytes counts (OR 0.79; 95% CI, 0.63–0.99; p = 0.04)] were associated with the presence of lung comets. Patients with higher NK cells (>15.4%, n = 15) were more likely to be rapid transporters (D/P creatinine 0.76 ± 0.1 vs. 0.69 ± 0.08, p = 0.04). Patients displaying higher Tregs (>1.79%) were older (70.8 ± 10.7 years vs. 57.7 ± 14.7years, p = 0.011) and had higher nPCR (0.83 ± 0.14 vs. 0.91 ± 0.17, p = 0.09).

Conclusion: Future research is required to evaluate the role of immune cells subsets as potential tools to identify patients at the highest risk for complications and guide interventions.

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.

Anti-inflammatory and Immunomodulatory Therapies in Atherosclerosis

Hypercholesterolemia is a major risk factor in atherosclerosis development and lipid-lowering drugs (i.e., statins) remain the treatment of choice. Despite effective reduction of LDL cholesterol in patients, a residual cardiovascular risk persists in some individuals, highlighting the need for further therapeutic intervention. Recently, the CANTOS trial paved the way toward the development of specific therapies targeting inflammation, a key feature in atherosclerosis progression. The pre-existence of multiple drugs modulating both innate and adaptive immune responses has significantly accelerated the number of translational studies applying these drugs to atherosclerosis. Additional preclinical research has led to the discovery of new therapeutic targets, offering promising perspectives for the treatment and prevention of atherosclerosis. Currently, both drugs with selective targeting and broad unspecific anti-inflammatory effects have been tested. In this chapter, we aim to give an overview of current advances in immunomodulatory treatment approaches for atherosclerotic cardiovascular diseases.

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.

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.

T cell subsets and functions in atherosclerosis

Atherosclerosis is a chronic inflammatory disease of the arterial wall and the primary underlying cause of cardiovascular disease. Data from in vivo imaging, cell-lineage tracing and knockout studies in mice, as well as clinical interventional studies and advanced mRNA sequencing techniques, have drawn attention to the role of T cells as critical drivers and modifiers of the pathogenesis of atherosclerosis. CD4+ T cells are commonly found in atherosclerotic plaques. A large body of evidence indicates that T helper 1 (TH1) cells have pro-atherogenic roles and regulatory T (Treg) cells have anti-atherogenic roles. However, Treg cells can become pro-atherogenic. The roles in atherosclerosis of other TH cell subsets such as TH2, TH9, TH17, TH22, follicular helper T cells and CD28null T cells, as well as other T cell subsets including CD8+ T cells and γδ T cells, are less well understood. Moreover, some T cells seem to have both pro-atherogenic and anti-atherogenic functions. In this Review, we summarize the knowledge on T cell subsets, their functions in atherosclerosis and the process of T cell homing to atherosclerotic plaques. Much of our understanding of the roles of T cells in atherosclerosis is based on findings from experimental models. Translating these findings into human disease is challenging but much needed. T cells and their specific cytokines are attractive targets for developing new preventive and therapeutic approaches including potential T cell-related therapies for atherosclerosis.

2019 ATVB Plenary Lecture: Interleukin-2 Therapy in Cardiovascular Disease: The Potential to Regulate Innate and Adaptive Immunity

Regulatory T cells and type-2 innate lymphoid cells represent 2 subsets of immune cells, which have been shown in preclinical models to be important in atherosclerosis and myocardial repair. Regulatory T cells play a crucial role in immune homeostasis and tolerance via their interactions with effector T cells, dendritic cells, and monocytes/macrophages. They also utilize and secrete inhibitory cytokines, including interleukin 10 and transforming growth factor β, to regulate or suppress pathogenic immune responses. Type-2 innate lymphoid cells have an important role in type-2 immune responses and tissue repair through secreting interleukins 5 and 13, as well as a variety of biological mediators and growth factors. Intriguingly, interleukin-2 has emerged as a common cytokine, which can be harnessed to upregulate both cell types, and also has important translational consequences as clinical trials are ongoing for its use in cardiovascular disease. Here, we briefly review the biology of these regulatory immune cell types, discuss the preclinical and clinical evidence for their functions in cardiovascular disease, examine the prospects for clinical translation and current ongoing trials, and finally, postulate how overlap in the mechanisms of upregulation may be leveraged in future treatments for patients.

Innate and adaptive immune cell subsets as risk factors for coronary heart disease in two population-based cohorts

BACKGROUND AND AIMS

Cell-mediated immunity is implicated in atherosclerosis. We evaluated whether innate and adaptive immune cell subsets in peripheral blood are risk factors for coronary heart disease.

METHODS

A nested case-cohort study (n = 2155) was performed within the Multi-Ethnic Study of Atherosclerosis (MESA) and the Cardiovascular Health Study (CHS). Cases of incident myocardial infarction (MI) and incident angina (n = 880 total cases) were compared with a cohort random sample (n = 1275). Immune cell phenotypes (n = 34, including CD14⁺ monocytes, natural killer cells, γδ T cells, CD4⁺, CD8⁺ and CD19⁺ lymphocyte subsets) were measured from cryopreserved cells by flow cytometry. Cox proportional hazards models with adjustment for cardiovascular disease risk factors were used to evaluate associations of cell phenotypes with incident MI and a composite phenotype of incident MI or incident angina (MI-angina) over a median 9.3 years of follow-up. Th1, Th2, Th17, T regulatory (CD4⁺CD25⁺CD127^-), naive (CD4⁺CD45RA⁺), memory (CD4⁺CD45RO⁺), and CD4⁺CD28^- cells were specified as primary hypotheses. In secondary analyses, 27 additional cell phenotypes were investigated.

RESULTS

After correction for multiple testing, there were no statistically significant associations of CD4⁺ naive, memory, CD28^-, or T helper cell subsets with MI or MI-angina in MESA, CHS, or combined-cohort meta analyses. Null associations were also observed for monocyte subsets, natural killer cells, γδ T cells, CD19⁺ B cell and differentiated CD4⁺ and CD8⁺ cell subsets.

CONCLUSIONS

The proportions of peripheral blood monocyte and lymphocyte subsets are not strongly related to the future occurrence of MI or angina in adults free of autoimmune disease.

The Hypermethylation of Foxp3 Promoter Impairs the Function of Treg Cells in EAP

Treg cells are crucial for maintaining immune homeostasis in CP/CPPS, but the molecular mechanisms underlying the modulation of the function of Treg in CP/CPPS remain unclear. The main purpose of this study is to investigate the relationship between immunosuppressive function of Treg and the methylation level of Foxp3 promoter in experimental autoimmune prostatitis (EAP) mouse model. EAP model was induced by subcutaneous injecting prostate-steroid-binding protein (PSBP) and complete Freund's adjuvant with NOD mice. Histological analysis revealed that EAP model was successfully induced. The expression of IFN-γ was increased, and TGF-β was decreased in the serum of EAP, respectively. The percentage of Tregs in splenic lymphocyte was increased in EAP. The suppressive ability of Tregs on Teffs was impaired in EAP. The methylation level of Foxp3 promoter was increased, and the expression of Foxp3 was decreased in EAP. By injection AZA which was DNA-methylation inhibitor into EAP mice, prostate inflammation was alleviated, expressions of TGF-β and Foxp3 were increased, and the suppressive function of Tregs was improved in vitro and in vivo. Thus, we concluded that aberrant increased methylation of Foxp3 promoter in Treg cells leads to the impaired suppressive function of Treg cells, exacerbating autoimmune inflammatory injury in EAP.

Immunobiology of Atherosclerosis: A Complex Net of Interactions

Cardiovascular disease is the leading cause of mortality worldwide, and atherosclerosis the principal factor underlying cardiovascular events. Atherosclerosis is a chronic inflammatory disease characterized by endothelial dysfunction, intimal lipid deposition, smooth muscle cell proliferation, cell apoptosis and necrosis, and local and systemic inflammation, involving key contributions to from innate and adaptive immunity. The balance between proatherogenic inflammatory and atheroprotective anti-inflammatory responses is modulated by a complex network of interactions among vascular components and immune cells, including monocytes, macrophages, dendritic cells, and T, B, and foam cells; these interactions modulate the further progression and stability of the atherosclerotic lesion. In this review, we take a global perspective on existing knowledge about the pathogenesis of immune responses in the atherosclerotic microenvironment and the interplay between the major innate and adaptive immune factors in atherosclerosis. Studies such as this are the basis for the development of new therapies against atherosclerosis.

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.

Disruption of the CCL1-CCR8 axis inhibits vascular Treg recruitment and function and promotes atherosclerosis in mice

The CC chemokine 1 (CCL1, also called I-309 or TCA3) is a potent chemoattractant for leukocytes that plays an important role in inflammatory processes and diseases through binding to its receptor CCR8. Here, we investigated the role of the CCL1-CCR8 axis in atherosclerosis. We found increased expression of CCL1 in the aortas of atherosclerosis-prone fat-fed apolipoprotein E (Apoe)-null mice; moreover, in vitro flow chamber assays and in vivo intravital microscopy demonstrated an essential role for CCL1 in leukocyte recruitment. Mice doubly deficient for CCL1 and Apoe exhibited enhanced atherosclerosis in aorta, which was associated with reduced plasma levels of the anti-inflammatory interleukin 10, an increased splenocyte Th1/Th2 ratio, and a reduced regulatory T cell (Treg) content in aorta and spleen. Reduced Treg recruitment and aggravated atherosclerosis were also detected in the aortas of fat-fed low-density lipoprotein receptor-null mice treated with CCR8 blocking antibodies. These findings demonstrate that disruption of the CCL1-CCR8 axis promotes atherosclerosis by inhibiting interleukin 10 production and Treg recruitment and function.

Elevated circulating effector memory T cells but similar levels of regulatory T cells in patients with type 2 diabetes mellitus and cardiovascular disease

Type 2 diabetes mellitus is associated with an elevated risk of cardiovascular disease, but the mechanism through which diabetes contributes to cardiovascular disease development remains incompletely understood. In this study, we compared the association of circulating regulatory T cells, naïve T cells, effector memory T cells or central memory T cells with cardiovascular disease in patients with and without type 2 diabetes mellitus. Percentage of circulating T cell subsets was analysed by flow cytometry in type 2 diabetes mellitus subjects with and without prevalent cardiovascular disease as well as in non-diabetic subjects with and without prevalent cardiovascular disease from the Malmö SUMMIT cohort. Subjects with type 2 diabetes mellitus had elevated percentages of effector memory T cells (CD4⁺CD45RO⁺CD62L^-; 21.8% ± 11.2% vs 17.0% ± 9.2% in non-type 2 diabetes mellitus, p < 0.01) and central memory T cells (CD4⁺CD45RO⁺CD62L⁺; 38.0% ± 10.7% vs 36.0% ± 9.5% in non-type 2 diabetes mellitus, p < 0.01). In contrast, the frequency of naïve T cells was reduced (CD4⁺CD45RO^-CD62L⁺, 35.0% ± 16.5% vs 42.9% ± 14.4% in non-type 2 diabetes mellitus, p < 0.001). The proportion of effector memory T cells was increased in type 2 diabetes mellitus subjects with cardiovascular disease as compared to those without (26.4% ± 11.5% vs 18.4% ± 10.2%, p < 0.05), while no difference in regulatory T cells was observed between these two patient groups. This study identifies effector memory T cells as a potential cellular biomarker for cardiovascular disease among subjects with type 2 diabetes mellitus, suggesting a state of exacerbated immune activation in type 2 diabetes mellitus patients with cardiovascular disease.

The Role of Circulating Regulatory T Cell Levels on Subclinical Atherosclerosis and Cardiovascular Risk Factors in Women with Systemic Lupus Erythematosus

The increase in cardiovascular disease (CVD) in patients with systemic lupus erythematosus (SLE) is not fully explained by traditional CVD risk factors. Regulatory T cells (Treg cells) are considered atheroprotective. We investigated the relationship between the absolute number of different phenotypes of Treg cells and abnormal carotid intima-media thickness (IMT) in women with SLE. Sixty-six women with SLE with no history of CV disease were included. Carotid IMT was quantified by ultrasound. Abnormal carotid IMT was defined as ≥0.8 mm and two groups were compared according to this definition. Flow cytometry was used to analyze Foxp3 and Helios expression in peripheral blood CD4 T cells. A significantly higher level of absolute CD4+CD25+FoxP3^high T cells was present in patients with abnormal carotid IMT compared with those without (1.795 ± 4.182 cells/μl vs. 0.274 ± 0.784 cells/μl; p = 0.003). However, no correlations were found between any Treg cell phenotypes and carotid IMT. Only the absolute number of CD4+CD45RA+FoxP3^low T cells was significantly decreased in SLE patients with low HDL cholesterol compared with those with normal HDL cholesterol (0.609 ± 2.362 cells/μl vs. 1.802 ± 4.647 cells/μl; p = 0.009 and 15.358 ± 11.608 cells/μl vs. 28.274 ± 34.139; p = 0.012, respectively). In conclusion, in SLE women, diminished levels of Treg cells based on flow cytometry were not a good indicator of abnormal carotid IMT.

Correlation of interleukin 6 and transforming growth factor β1 with peripheral blood regulatory T cells in rheumatoid arthritis patients: a potential biomarker

Introduction

Proinflammatory cytokines and regulatory T cells (Tregs) are considered as important factors involved in autoimmunity development especially in rheumatoid arthritis (RA).

Aim of the study

To investigate the frequency of peripheral blood Tregs and related cytokines in RA patients and to determine the possible correlation between Treg percentage and interleukin 6 (IL-6) and transforming growth factor β1 (TGF-β1) as indicators in assessment of Treg function and mechanisms preceding autoimmunity in RA.

Material and methods

Thirty-seven Iranian RA patients with a moderate (3.2-5.1) disease activity score (DAS) and the same number of healthy age- and sex-matched individuals were enrolled. Frequency of peripheral blood Tregs (CD4⁺FoxP3⁺CD25^high) was determined by flow cytometry. Serum levels of IL-6 and TGF-β1 and their expression levels in peripheral blood mononuclear cells (PBMCs) were evaluated by ELISA and Q-PCR, respectively.

Results

Rheumatoid arthritis patients showed significantly lower peripheral blood Treg frequencies compared to healthy individuals. Additionally, Treg (%) showed a significant inverse correlation between serum concentrations of IL-6 and mRNA expression of PBMCs, whereas there was no significant correlation between Treg (%) and TGF-β1 levels.

Conclusions

The current study revealed that Treg numbers were reduced in peripheral blood of RA patients. This reduction inversely correlated with IL-6 levels, which may lead to persistent autoimmune and inflammatory conditions in RA patients.

The expression and clinical correlations of 4-1BB on peripheral CD4+ T cell subsets in patients with coronary artery disease. A cross-sectional pilot study

BACKGROUND

The expression of 4-1BB on peripheral regulatory T cells (Tregs) and conventional T cells (Tconvs) in coronary artery disease (CAD) patients is unknown. We aimed to investigate the expression and clinical correlations of 4-1BB on peripheral Tregs and Tconvs in CAD patients.

METHODS

Flow cytometry analysis was used to analyze 4-1BB expression on peripheral Tregs and Tconvs. We compared the percentages of 4-1BB on Tregs and Tconvs in the control (ctrl) group, the stable ischemic heart disease (SIHD) group, and the acute coronary syndrome (ACS) group. The correlations of 4-1BB expression on Tregs and Tconvs with the Gensini score and CRP were examined in the ACS group. The value of 4-1BB percentage on Tregs for predicting CAD in this cardiovascular risk population was also analyzed.

RESULTS

A total of 71 participants were enrolled in this study. In all the groups, the percentages of 4-1BB on Tregs were significantly higher than on Tconvs (all P < .05). After adjusting for sex, age, SBP, HbA1c and LDL, 4-1BB percentages on Tregs and Tconvs were significantly higher in the SIHD and ACS groups compared with the ctrl group (all P < .05). The ratio of 4-1BB percentage on Tregs to 4-1BB percentage on Tconvs was higher in the ACS group compared with the ctrl group (P = .010). In the ACS group, CRP was negatively correlated with the Tregs percentage (in CD4+ T cells) and the Tregs percentage to Tconvs percentage ratio. The Gensini score was positively correlated with the 4-1BB percentage on Tregs in the ACS group. Linear regression analysis showed 4-1BB percentage on Tregs independently predicted the Gensini score. Binary logistic regression showed CRP, HbA1c and 4-1BB percentage on Tregs independently predicted the development of CAD (SIHD+ACS) in the whole population.

CONCLUSION

4-1BB expression on peripheral Tregs and Tconvs was increased in SIHD and ACS patients. 4-1BB percentage on Tregs positively correlated with the severity of coronary artery stenosis in ACS patients. 4-1BB percentage on Tregs independently predicted the severity of coronary artery stenosis in an ACS population and development of CAD in a cardiovascular risk population.

Low-dose interleukin-2 in patients with stable ischaemic heart disease and acute coronary syndromes (LILACS): protocol and study rationale for a randomised, double-blind, placebo-controlled, phase I/II clinical trial

INTRODUCTION

Inflammation and dysregulated immune responses play a crucial role in atherosclerosis, underlying ischaemic heart disease (IHD) and acute coronary syndromes (ACSs). Immune responses are also major determinants of the postischaemic injury in myocardial infarction. Regulatory T cells (CD4⁺CD25⁺FOXP3⁺; Treg) induce immune tolerance and preserve immune homeostasis. Recent in vivo studies suggested that low-dose interleukin-2 (IL-2) can increase Treg cell numbers. Aldesleukin is a human recombinant form of IL-2 that has been used therapeutically in several autoimmune diseases. However, its safety and efficacy is unknown in the setting of coronary artery disease.

METHOD AND ANALYSIS

Low-dose interleukin-2 in patients with stable ischaemic heart disease and acute coronary syndromes is a single-centre, first-in-class, dose-escalation, two-part clinical trial. Patients with stable IHD (part A) and ACS (part B) will be randomised to receive either IL-2 (aldesleukin; dose range 0.3-3×10⁶ IU) or placebo once daily, given subcutaneously, for five consecutive days. Part A will have five dose levels with five patients in each group. Group 1 will receive a dose of 0.3×10⁶ IU, while the dose for the remaining four groups will be determined on completion of the preceding group. Part B will have four dose levels with eight patients in each group. The dose of the first group will be based on part A. Doses for each of the subsequent three groups will similarly be determined after completion of the previous group. The primary endpoint is safety and tolerability of aldesleukin and to determine the dose that increases mean circulating Treg levels by at least 75%.

ETHICS AND DISSEMINATION

The study received a favourable opinion by the Greater Manchester Central Research Ethics Committee, UK (17/NW/0012). The results of this study will be reported through peer-reviewed journals, conference presentations and an internal organisational report.

TRIAL REGISTRATION NUMBER

NCT03113773; Pre-results.

Myeloid apolipoprotein E controls dendritic cell antigen presentation and T cell activation

Cholesterol homeostasis has a pivotal function in regulating immune cells. Here we show that apolipoprotein E (apoE) deficiency leads to the accumulation of cholesterol in the cell membrane of dendritic cells (DC), resulting in enhanced MHC-II-dependent antigen presentation and CD4⁺ T-cell activation. Results from WT and apoE KO bone marrow chimera suggest that apoE from cells of hematopoietic origin has immunomodulatory functions, regardless of the onset of hypercholesterolemia. Humans expressing apoE4 isoform (ε4/3–ε4/4) have increased circulating levels of activated T cells compared to those expressing WT apoE3 (ε3/3) or apoE2 isoform (ε2/3–ε2/2). This increase is caused by enhanced antigen-presentation by apoE4-expressing DCs, and is reversed when these DCs are incubated with serum containing WT apoE3. In summary, our study identifies myeloid-produced apoE as a key physiological modulator of DC antigen presentation function, paving the way for further explorations of apoE as a tool to improve the management of immune diseases.

Cholesterol homeostasis can modulate immunity via multiple pathways. Here the authors show that apolipoprotein E, an important regulator of cholesterol, produced by myeloid cells can regulate T cell activation by controlling the antigen presentation activity of dendritic cells in both humans and mice.

Disease trends over time and CD4+CCR5+ T-cells expansion predict carotid atherosclerosis development in patients with systemic lupus erythematosus

BACKGROUND AND AIM

Patients with Systemic Lupus Erythematosus (SLE) present increased cardiovascular mortality compared to the general population. Few studies have assessed the long-term development and progression of carotid atherosclerotic plaque in SLE patients. Our aim was to investigate the association of clinical and laboratory markers of disease activity and classical cardiovascular risk factors (CVRF) with carotid atherosclerosis development in SLE patients in a prospective 5-year study.

METHODS AND RESULTS

Clinical history and information on principal CVRFs were collected at baseline and after 5 years in 40 SLE patients (36 women, mean age 42 ± 9 years; 14.4 ± 7 years of mean disease duration) and 50 age-matched controls. Carotid Doppler ultrasonography was employed to quantify the atherosclerotic burden at baseline and at follow up. Clinimetrics were applied to assess SLE activity over time (SLEDAI). The association between basal circulating T cell subsets (including CD4⁺CCR5⁺; CD4⁺CXCR3⁺; CD4⁺HLADR⁺; CD4⁺CD45RA⁺RO^-, CD4⁺CD45RO⁺RA^- and their subsets) and atherosclerosis development was evaluated. During the 5-year follow up, 32% of SLE patients, developed carotid atherosclerosis compared to 4% of controls. Furthermore, considering SLEDAI changes over time, patients within the highest tertile were those with increased incidence of carotid atherosclerosis independently of CVRF. In addition, increased levels of CD4⁺CCR5⁺ T cells were independently associated with the development of carotid atherosclerosis in SLE patients.

CONCLUSION

Serial clinical evaluations over time, rather than a single point estimation of disease activity or CVRF burden, are required to define the risk of carotid atherosclerosis development in SLE patients. Specific T cell subsets are associated with long-term atherosclerotic progression and may further be of help in predicting vascular disease progression.

Decreased Helios Expression in Regulatory T Cells in Acute Coronary Syndrome

Regulatory T cells (Tregs) play an essential role in acute coronary syndrome (ACS). However, there is debate about which Treg subsets are truly critical to ACS. Helios, a transcription factor, was recently reported to be a bona fide marker for natural Tregs or activated Tregs with a suppression function, but little is known about its role in ACS. We therefore examined Helios+ Tregs in patients with ACS, patients with stable angina, and control subjects. 73 patients with ACS, 30 patients with stable angina, and 48 control subjects were enrolled. The frequencies and estimated absolute numbers of different Treg subsets in peripheral blood were measured by flow cytometry. Plasma cytokine level was measured by ELISA. The mRNA expression of Foxp3 and Helios in purified CD4+ T cells was determined by RT-PCR. Helios+ Tregs was decreased significantly in patients with ACS. The frequency and estimated absolute numbers of CD4+Foxp3+Helios+ Tregs were negatively correlated with IL-6 and positively correlated with circulating level of TGF-beta1 and HDL-C. The mRNA expression of Foxp3 and Helios was decreased in CD4+ T cells from patients with ACS. In summary, Helios+ Tregs was downregulated in patients with ACS and may play a role in ACS.

Activation-induced FOXP3 isoform profile in peripheral CD4+ T cells is associated with coronary artery disease

BACKGROUND AND AIMS

The expression of FOXP3 isoforms affects regulatory T (Treg) cell function. Reduced Treg cell function has been associated with coronary artery disease (CAD). However, alternative splicing of FOXP3 in CAD has not been investigated.

METHODS

FOXP3 splice variants and IL17A transcripts in peripheral blood mononuclear cells from stable CAD patients and healthy controls were quantified, and FOXP3 isoform expression in response to T cell receptor (TCR) stimulation or LDL was analyzed by flow cytometry.

RESULTS

Compared to healthy controls, CAD patients expressed significantly more FOXP3 transcripts that included exon 2, whereas alternative splicing of exon 7 in correlation with IL17A expression was reduced. Moreover, TCR stimulation, as well as exposure to LDL, decreased alternative splicing of FOXP3 in CD4+ T cells in vitro.

CONCLUSIONS

Our results demonstrate that blood mononuclear cells in stable CAD patients express a ratio of FOXP3 isoforms that is characteristic for activated CD4+ T cells.

Translating the biology of adipokines in atherosclerosis and cardiovascular diseases: Gaps and open questions

AIM

Critically discuss the available data, to identify the current gaps and to provide key concepts that will help clinicians in translating the biology of adipokines in the context of atherosclerosis and cardio-metabolic diseases.

DATA SYNTHESIS

Adipose tissue is nowadays recognized as an active endocrine organ, a function related to the ability to secrete adipokines (such as leptin and adiponectin) and pro-inflammatory cytokines (tumor necrosis factor alpha and resistin). Studies in vitro and in animal models have observed that obesity status presents a chronic low-grade inflammation as the consequence of the immune cells infiltrating the adipose tissue as well as adipocytes. This inflammatory signature is often related to the presence of cardiovascular diseases, including atherosclerosis and thrombosis. These links are less clear in humans, where the role of adipokines as prognostic marker and/or player in cardiovascular diseases is not as clear as that observed in experimental models. Moreover, plasma adipokine levels might reflect a condition of adipokine-resistance in which adipokine redundancy occurs. The investigation of the cardio-metabolic phenotype of carriers of single nucleotide polymorphisms affecting the levels or function of a specific adipokine might help determine their relevance in humans. Thus, the aim of the present review is to critically discuss the available data, identify the current gaps and provide key concepts that will help clinicians translate the biology of adipokines in the context of atherosclerosis and cardio-metabolic diseases.

Obesity-Induced Metabolic Stress Leads to Biased Effector Memory CD4+ T Cell Differentiation via PI3K p110δ-Akt-Mediated Signals

Low-grade systemic inflammation associated to obesity leads to cardiovascular complications, caused partly by infiltration of adipose and vascular tissue by effector T cells. The signals leading to T cell differentiation and tissue infiltration during obesity are poorly understood. We tested whether saturated fatty acid-induced metabolic stress affects differentiation and trafficking patterns of CD4+ T cells. Memory CD4+ T cells primed in high-fat diet-fed donors preferentially migrated to non-lymphoid, inflammatory sites, independent of the metabolic status of the hosts. This was due to biased CD4+ T cell differentiation into CD44hi-CCR7lo-CD62Llo-CXCR3+-LFA1+ effector memory-like T cells upon priming in high-fat diet-fed animals. Similar phenotype was observed in obese subjects in a cohort of free-living people. This developmental bias was independent of any crosstalk between CD4+ T cells and dendritic cells and was mediated via direct exposure of CD4+ T cells to palmitate, leading to increased activation of a PI3K p110δ-Akt-dependent pathway upon priming.

Reconfiguration of NKT Cell Subset Compartment Is Associated with Plaque Development in Patients with Carotid Artery Stenosis

Accumulating evidence shows that immune cells play an important role in carotid atherosclerotic plaque development. In this study, we assessed the association of 6 different natural killer T (NKT) cell subsets, based on CD57 and CD8 expression, with risk for development of carotid atherosclerotic plaque (CAP). Molecular expression by peripheral NKT cells was evaluated in 13 patients with high-risk CAP and control without carotid stenosis (n = 18). High-risk CAP patients, compared with healthy subjects, had less percentage of CD57+CD8- NKT cell subsets (8.64 ± 10.15 versus 19.62 ± 10.8 %; P = 0.01) and CD57+CD8int NKT cell subsets (4.32 ± 3.04 versus 11.87 ± 8.56 %; P = 0.002), with a corresponding increase in the CD57-CD8high NKT cell subsets (33.22 ± 11.87 versus 18.66 ± 13.68 %; P = 0.007). Intracellular cytokine staining showed that CD8+ NKT cell subset was the main cytokine-producing NKT cell. Cytokine production in plasma was measured with Bio-Plex assay. The expression levels of pro-inflammatory mediators (IFN-γ, IL-17, IP-10) were significantly higher in CAP patients as compared to that from controls. These data provide evidence that NKT cell subset compartment reconfiguration in patients with carotid stenosis seems to be associated with the occurrence of carotid atherosclerotic plaque and suggest that both pathogenic and protective NKT cell subsets exist.

CD4+ Foxp3+ T-cells contribute to myocardial ischemia-reperfusion injury

OBJECTIVE

The present study analyzed the effect of CD4⁺ Forkhead box protein 3 negative (Foxp3^-) T-cells and Foxp3⁺ CD4⁺ T-cells on infarct size in a mouse myocardial ischemia-reperfusion model.

APPROACH AND RESULTS

We examined the infarct size as a fraction of the area-at-risk as primary study endpoint in mice after 30minutes of coronary ligation followed by 24hours of reperfusion. CD4⁺ T-cell deficient MHC-II KO mice showed smaller histologically determined infarct size (34.5±4.7% in MHCII KO versus 59.4±4.9% in wildtype (WT)) and better preserved ejection fraction determined by magnetic resonance tomography (56.9±2.8% in MHC II KO versus 39.0±4.2% in WT). MHC-II KO mice also displayed better microvascular perfusion than WT mice after 24hours of reperfusion. Also CD4⁺ T-cell sufficient OT-II mice, which express an in this context irrelevant T-cell receptor, revealed smaller infarct sizes compared to WT mice. However, MHC-II blocking anti-I-A/I-E antibody treatment was not able to reduce infarct size indicating that autoantigen recognition is not required for the activation of CD4⁺ T-cells during reperfusion. Flow-cytometric analysis also did not detect CD4⁺ T-cell activation in heart draining lymph nodes in response to 24hours of ischemia-reperfusion. Adoptive transfer of CD4⁺ T-cells in CD4 KO mice increased the infarct size only when including the Foxp3⁺ CD25⁺ subset. Depletion of CD4⁺ Foxp3⁺ T-cells in DEREG mice enabling specific conditional ablation of this subset by treatment with diphtheria toxin attenuated infarct size as compared to diphtheria toxin treated WT mice.

CONCLUSIONS

CD4⁺ Foxp3⁺ T-cells enhance myocardial ischemia-reperfusion injury. CD4⁺ T-cells exert injurious effects without the need for prior activation by MHC-II restricted autoantigen recognition.

Circulating CD14+ and CD14highCD16- classical monocytes are reduced in patients with signs of plaque neovascularization in the carotid artery

BACKGROUND AND AIMS

Monocytes are known to play a key role in the initiation and progression of atherosclerosis and contribute to plaque destabilization through the generation of signals that promote inflammation and neoangiogenesis. In humans, studies investigating the features of circulating monocytes in advanced atherosclerotic lesions are lacking.

METHODS

Patients (mean age 69 years, 56% males) with intermediate asymptomatic carotid stenosis (40-70% in diameter) were evaluated for maximal stenosis in common carotid artery, carotid bulb and internal carotid artery, overall disease burden as estimated with total plaque area (TPA), greyscale and neovascularization in 244 advanced carotid plaques. Absolute counts of circulating CD14+ monocytes, of classical (CD14^highCD16-), intermediate (CD14^highCD16+) and non-classical (CD14^lowCD16+) monocytes and HLA-DR+ median fluorescence intensity for each subset were evaluated with flow cytometry.

RESULTS

No correlation was found between monocytes and overall atherosclerotic burden, nor with high sensitivity C-reactive protein (hsCRP) or interleukin-6 (IL-6). In contrast, plaque signs of neovascularization were associated with significantly lower counts of circulating CD14+ monocytes (297 versus 350 cells/mm³, p = 0.039) and of classical monocytes (255 versus 310 cells/mm³, p = 0.029).

CONCLUSIONS

Neovascularized atherosclerotic lesions selectively associate with lower blood levels of CD14+ and CD14^highCD16- monocytes independently of systemic inflammatory activity, as indicated by normal hsCRP levels. Whether the reduction of circulating CD14+ and CD14^highCD16- monocytes is due to a potential redistribution of these cell types into active lesions remains to be explored.

Stabilization of high-risk plaques

The prevalence of atherosclerotic cardiovascular diseases (ASCVDs) is increasing globally and they have become the leading cause of death in most countries. Numerous experimental and clinical studies have been conducted to identify major risk factors and effective control strategies for ASCVDs. The development of imaging modalities with the ability to determine the plaque composition enables us to further identify high-risk plaque and evaluate the effectiveness of different treatment strategies. While intensive lipid-lowering by statins can stabilize or even regress plaque by various mechanisms, such as the reduction of lipid accumulation in a necrotic lipid core, the reduction of inflammation, and improvement of endothelial function, there are still considerable residual risks that need to be understood. We reviewed important findings regarding plaque vulnerability and some encouraging emerging approaches for plaque stabilization.

The Ratio of Regulatory (FOXP3+) to Total (CD3+) T Cells Determined by Epigenetic Cell Counting and Cardiovascular Disease Risk: A Prospective Case-cohort Study in Non-diabetics

Background

Experimental and clinical evidence indicate that inflammatory processes in atherogenesis and the development of cardiovascular complications are promoted by a loss of regulatory T cell (Treg)-mediated immunological tolerance to plaque antigens. Yet, the association between alterations of systemic Treg frequency and cardiovascular disease incidence remains uncertain.

Methods

A nested case-cohort study was conducted within the European Prospective Investigation into Cancer and Nutrition (EPIC)-Heidelberg, comprising a random subcohort (n = 778) and primary cases of myocardial infarction (MI, n = 276) and ischemic stroke (n = 151). Pre-diagnostic FOXP3 + Treg and total CD3 + T-lymphocyte (tTL) frequencies in blood were measured by epigenetic-based, quantitative real-time PCR-assisted cell counting.

Results

Multivariate, Prentice-weighted Cox regression analyses revealed that lower Treg/tTL ratios were not associated with the risk of either MI (lowest vs. highest sex-specific quartile; hazard ratio: 0.72, 95% confidence interval: 0.46 to 1.13; P_trend = 0.51) or stroke (HR: 0.90, 95% CI: 0.51 to 1.60; P_trend = 0.78). There were no correlations of Treg/tTL ratios with C-reactive protein, HbA1c, and various lipid parameters.

Conclusions

Among middle-aged adults from the general population, imbalances in the relative frequency of Tregs within the total T cell compartment do not confer an increased risk of MI or stroke.

•

We studied if peripheral immune tolerance, as reflected by regulatory (FOXP3+) to total (CD3+) T cells, relates to CVD risk.

•

Epigenetic-based, qPCR assisted cell counting was used to quantify T cell subsets in long-term stored buffy coat samples.

•

Lower Treg-mediated immune tolerance does not confer an increased risk of major CVD events.

Inflammation in the arterial intima plays a central role in atherosclerotic cardiovascular disease and may develop owing to autoimmune-like responses targeted against plaque antigens. While the ratio between regulatory T cells (Tregs) and effector T cells is thought to control such immune response outcomes and tolerance within the T cell compartment, we found no association with incidence of major CVD events. These findings imply that reduced systemic Treg frequencies observed in CVD patients follow rather than precede disease manifestation and that Treg variation within a physiological range may not – as previously reported - constitute a pre-disposing risk factor for CVD.

Circulating regulatory T cells in patients with aortic valve stenosis: Association with disease progression and aortic valve intervention

BACKGROUND

Severe aortic valve stenosis (AS) accounts for considerable morbidity and death, especially in older patients. There is increasing evidence to suggest a role for immune modulating cells in aortic valve (AV) degeneration. Regulatory T cells (Tregs) tune down inflammation. We aimed to study the levels of circulating Tregs in patients with AS and to assess their association with disease progression.

METHOD AND RESULTS

The number of Tregs (CD4+CD25+Foxp3+) was determined by flow cytometry in 229 patients with AS and a control group of 69 patients. Tregs were significantly higher in patients with AS compared to the control group (1.64± .61% vs 1.13±0.97%, p=0.04). In the logistic regression analysis, adjusted for baseline characteristics, only the hemoglobin level and Treg percent correlated with the presence of AS (OR 0.642 95% CI 0.512-0.805, p<0.001 and OR 1.411, 95% CI 1.080-1.844, p=0.011, respectively). One hundred patients underwent 2 echocardiographic studies during follow-up. The median decrease in AV area (AVA) was 0.1cm(2)/year. A borderline association was observed between Tregs and AVA progression (r=0.19, p=0.054). In a subgroup of 68 patients with severe AS, the association between Tregs and AVA progression was significant (r=0.374, p=0.0017). In addition, a drop in Treg levels was observed 3-6months after AV-intervention (1.86±1.6% vs 1.04±1.8%, p=0.0005).

CONCLUSIONS

Circulating Tregs are elevated in patients with AS. The levels of Tregs are higher in patients with severe AS and accelerated progression of valve narrowing. These results may help to identify AS patients with accelerated disease progression and possibly in need for earlier intervention.

Regulatory T cells in atherosclerosis: critical immune regulatory function and therapeutic potential

Atherosclerosis is a chronic inflammatory disease that is mediated by innate and adaptive immune responses. The disease is characterized by sub-endothelial accumulation and modification of lipids in the artery wall triggering an inflammatory reaction which promotes lesion progression and eventual plaque rupture, thrombus formation, and the respective clinical sequelae such as myocardial infarction or stroke. During the past decade, T-cell-mediated immune responses, especially control of pro-inflammatory signals by regulatory T cells (Tregs), have increasingly attracted the interest of experimental and clinical researchers. By suppression of T cell proliferation and secretion of anti-inflammatory cytokines, such as interleukin-10 (IL-10) and transforming growth factor-β, Tregs exert their atheroprotective properties. Atherosclerosis-prone, hyperlipidemic mice harbor systemically less Tregs compared to wild-type mice, suggesting an imbalance of immune cells which affects local and systemic inflammatory and potentially metabolic processes leading to atherogenesis. Restoring or increasing Treg frequency and enhancing their suppressive capacity by various modulations may pose a promising approach for treating inflammatory conditions such as cardiovascular diseases. In this review, we briefly summarize the immunological basics of atherosclerosis and introduce the role and contribution of different subsets of T cells. We then discuss experimental data and current knowledge pertaining to Tregs in atherosclerosis and perspectives on manipulating the adaptive immune system to alleviate atherosclerosis and cardiovascular disease.

Relationship between regulatory T cells subsets and lipid profile in dyslipidemic patients: a longitudinal study during atorvastatin treatment

Background

The CD4+ T-lymphocytes and their subtype CD4 + CD25^highFoxP3+ regulatory T cells are receiving growing interest as major regulators of atherogenesis. We sought to investigate 1) whether the CD4 + cell subsets were expressed differently in dyslipidemic patients (Pts) and healthy subjects (HS) and 2) whether atorvastatin treatment could be associated in-vivo and in-vitro with cell changes in expression and functional response.

Methods

CD4+ subsets frequency (CD4 + CD25^highFoxP3+, CD4 + CD25-FoxP3+) and mRNA expression for FoxP3, IL-10 and TGF-β were evaluated in 30 consecutive Pts at baseline and after a 3-month atorvastatin therapy, and in 17 HS.

Results

The % of CD4 + cells did not differ between HS and Pts. The % of CD4 + CD25^highFoxP3+ was higher in Pts than HS and did not change during treatment. The CD4 + CD25-FoxP3+ cells were similar between the two groups and were lower in Pts at visit 2. Cytokine expression and FoxP3 did not differ in HS and Pts and no substantial change was observed during treatment. At visit 1, CD4 + CD25^highFoxP3+ cells were significantly correlated with both total-cholesterol (r = 0.570, P = 0.0002), LDL-cholesterol (r = 0.715, P = 0.0001), Apolipoprotein B (r = 0.590, P = 0.0001). In-vitro atorvastatin (up to 5 μM) failed to induce any significant modulation of cell functions.

Conclusion

CD4 + CD25^highFoxP3+ regulatory cells seem to be over-stimulated in the early pre-clinical phase of atherosclerosis and a relationship exists between their frequency and circulating lipids. A potential immuno-modulation by statin treatment is not achieved through a normalization in peripheral CD4 + cell subsets.

Targeting T cells to treat atherosclerosis: odyssey from bench to bedside

More than 150 years from the initial description of inflammation in atherosclerotic plaques, randomized clinical trials to test anti-inflammatory therapies in atherosclerosis have recently been initiated. Lymphocytes and macrophages are main participants in the inflammatory response in atherosclerosis. T lymphocytes operate mainly by exerting strong influences on the function of many cells in the immune system and beyond, and co-ordinating their interactions. Importantly, T lymphocytes are not a homogenous population, but include several subsets with specialized functions that can either promote or suppress inflammation. The interactions between these T-lymphocyte subsets have critical consequences on the course and outcome of inflammation. The complexity of the inflammatory response in atherosclerosis poses significant challenges on translating experimental findings into clinical therapies and makes the journey from bench to bedside an arduous one. Here, we summarize recent advances on the role of CD4⁺ T cells in the inflammatory process in atherosclerosis and discuss potential therapies to modulate these lymphocytes that may provide future breakthroughs in the treatment of atherosclerosis.

The Cellular and Molecular Basis of Translational Immunometabolism

The immune response requires major changes to metabolic processes, and indeed, energy metabolism and functional activation are fully integrated in immune cells to determine their ability to divide, differentiate, and carry out effector functions. Immune cell metabolism has therefore become an attractive target area for therapeutic purposes. A neglected aspect in the translation of immunometabolism is the critical connection between systemic and cellular metabolism. Here, we discuss the importance of understanding and manipulating the integration of systemic and immune cell metabolism through in-depth analysis of immune cell phenotype and function in human metabolic diseases and, in parallel, of the effects of conventional metabolic drugs on immune cell differentiation and function. We examine how the recent identification of selective metabolic programs operating in distinct immune cell subsets and functions has the potential to deliver tools for cell- and function-specific immunometabolic targeting.

Functional and homeostatic defects of regulatory T cells in patients with coronary artery disease

OBJECTIVE

Regulatory T cells (Tregs) are considered atheroprotective, and low levels have been associated with the acute coronary syndrome (ACS), particularly non-ST elevation (NSTE)-ACS. However, the functional properties as well as homeostasis of Tregs are mainly unknown in coronary artery disease (CAD). Here, we investigated the composition and functional properties of naïve (n) and memory (m)Tregs in patients with NSTE-ACS and in patients 6-12 months post-ACS.

METHODS

Based on the expression of CD25, FOXP3, CD127, CD45RA, CD39 and CTLA-4, Treg subsets were defined by flow cytometry in whole blood or isolated CD4(+) T cells. The functional properties of nTregs and mTregs were examined in terms of proliferative capacity and modulation of cytokine secretion. To understand the potential consequences of Treg defects, we also investigated correlations with lipopolysaccharide (LPS)-induced cytokine secretion and ultrasound-defined carotid atherosclerosis.

RESULTS

Both NSTE-ACS and post-ACS patients exhibited reduced levels of nTregs (P < 0.001) compared with healthy control subjects, but without compensatory increases in mTregs. Both nTregs and mTregs from patients showed significantly lower replicative rates and impaired capacity to modulate T-cell proliferation and secretion of interferon-gamma and IL-10. The Treg defect was also associated with LPS-induced cytokine secretion and increased burden of carotid atherosclerosis.

CONCLUSION

Our results demonstrate a functional and homeostatic Treg defect in patients with NSTE-ACS and also in stabilized patients 6-12 months after ACS. Moreover, this defect was associated with a subclinical proinflammatory and atherogenic state. We believe that the failure to preserve Treg function and homeostasis reflects a need for immune-restoring strategies in CAD.

Lymphocyte subpopulations in myocardial infarction: a comparison between peripheral and intracoronary blood

The frequency and profile of lymphocyte subsets within the culprit coronary artery were investigated in 33 patients with myocardial infarction and compared to their systemic circulating counterparts. T cell subsets including CD4⁺CD28null, activated and regulatory T-cells, TH1/TH2/TH17 phenotypes, NK and B-cells were studied in intracoronary (IC) and arterial peripheral blood (PB) samples. CD4⁺CD28null T-lymphocytes were significantly increased in IC compared to PB (3.7 vs. 2.9 %, p < 0.0001). Moreover, patients with more than 6 h of evolution of STEMI exhibited higher levels of CD4⁺CD28null T-cells suggesting that this subset may be associated with more intense myocardial damage. The rare NK subpopulation CD3⁻CD16⁺CD56⁻ was also increased in IC samples (5.6 vs. 3.9 %, p = 0.006). CD4⁺CD28null T-cells and CD3⁻CD16⁺CD56⁻ NK subpopulations were also associated with higher CK levels. Additionally, IFN-γ and IL10 were significantly higher in IC CD4⁺ lymphocytes. Particular immune cell populations with a pro-inflammatory profile at the site of onset were increased relative to their circulating counterparts suggesting a pathophysiological role of these cells in plaque instability, thrombi and myocardial damage.

Human umbilical vein endothelial cells promote the inhibitory activation of CD4(+)CD25(+)Foxp3(+) regulatory T cells via PD-L1

BACKGROUND

Atherosclerosis (AS) is a chronic inflammation characterized by massive infiltration of inflammatory cells in arterial wall plaques. Programmed death ligand-1 (PD-L1), a co-stimulatory molecule, plays a vital role in regulating immune responses. We investigated the role and mechanisms of PD-L1 expressed on oxidized low-density lipoprotein (ox-LDL)-impaired human umbilical vein endothelial cells (HUVECs) in promoting activation and cytokine production of CD4(+)CD25(+) forkhead box P3 (FoxP3) regulatory T cells (Tregs).

METHODS AND RESULTS

Tregs were incubated alone, with HUVECs or HUVECs pre-stimulated with ox-LDL in the presence of anti-CD3 monoclonal antibodies (mAbs) for 48 h. HUVECs were shown to upregulate the immune phenotypic markers of Tregs, such as glucocorticoid-induced TNF receptor (GITR), cytotoxic T lymphocyte antigen-4 (CTLA-4) and programmed cell death-1 protein (PD-1). Moreover, HUVECs modulated cytokine production of Tregs (e.g., interleukin-10 (IL-10) and transforming growth factor-β1 (TGF-β1)). HUVECs treated with anti-PD-L1 mAbs were unable to regulate the surface expression and cytokine production of Tregs. The Transwell culture system suggested that interaction between HUVECs and Tregs via PD-L1 requires cell-to-cell contact.

CONCLUSION

Expression of the negative co-stimulatory molecule PD-L1 on HUVECs may upregulate the inhibitory activation and cytokine production of CD4(+)CD25(+)Foxp3(+) regulatory T cells in AS.