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

Association between Inflammation and New-Onset Atrial Fibrillation in Acute Coronary Syndromes

Acute coronary syndrome (ACS) is a complex clinical syndrome that encompasses acute myocardial infarction (AMI) and unstable angina (UA). Its underlying mechanism refers to coronary plaque disruption, with consequent platelet aggregation and thrombosis. Inflammation plays an important role in the progression of atherosclerosis by mediating the removal of necrotic tissue following myocardial infarction and shaping the repair processes that are essential for the recovery process after ACS. As a chronic inflammatory disorder, atherosclerosis is characterized by dysfunctional immune inflammation involving interactions between immune (macrophages, T lymphocytes, and monocytes) and vascular cells (endothelial cells and smooth muscle cells). New-onset atrial fibrillation (NOAF) is one of the most common arrhythmic complications in the setting of acute coronary syndromes, especially in the early stages, when the myocardial inflammatory reaction is at its maximum. The main changes in the atrial substrate are due to atrial ischemia and acute infarcts that can be attributed to neurohormonal factors. The high incidence of atrial fibrillation (AF) post-myocardial infarction may be secondary to inflammation. Inflammatory response and immune system cells have been involved in the initiation and development of atrial fibrillation. Several inflammatory indexes, such as C-reactive protein and interleukins, have been demonstrated to be predictive of prognosis in patients with ACS. The cell signaling activation patterns associated with fibrosis, apoptosis, and hypertrophy are forms of cardiac remodeling that occur at the atrial level, predisposing to AF. According to a recent study, the presence of fibrosis and lymphomononuclear infiltration in the atrial tissue was associated with a prior history of AF. However, inflammation may contribute to both the occurrence/maintenance of AF and its thromboembolic complications.

Overview of multifunctional Tregs in cardiovascular disease: From insights into cellular functions to clinical implications

Regulatory T cells (Tregs) are crucial in regulating T-cell-mediated immune responses. Numerous studies have shown that dysfunction or decreased numbers of Tregs may be involved in inflammatory cardiovascular diseases (CVDs) such as atherosclerosis, hypertension, myocardial infarction, myocarditis, cardiomyopathy, valvular heart diseases, heart failure, and abdominal aortic aneurysm. Tregs can help to ameliorate CVDs by suppressing excessive inflammation through various mechanisms, including inhibition of T cells and B cells, inhibition of macrophage-induced inflammation, inhibition of dendritic cells and foam cell formation, and induction of anti-inflammatory macrophages. Enhancing or restoring the immunosuppressive activity of Tregs may thus serve as a fundamental immunotherapy to treat hypertension and CVDs. However, the precise molecular mechanisms underlying the Tregs-induced protection against hypertension and CVDs remain to be investigated. This review focuses on recent advances in our understanding of Tregs subsets and function in CVDs. In addition, we discuss promising strategies for using Tregs through various pharmacological approaches to treat hypertension and CVDs.

Longitudinal Variations in Th and Treg Cells Before and After Percutaneous Coronary Intervention, and Their Intercorrelations and Prognostic Value in Acute Syndrome Patients

T helper (Th) and regulatory T (Treg) cells regulate atherosclerosis, plaque, inflammation to involve in acute coronary syndrome (ACS). The current study aimed to investigate the clinical implications of Th and Treg cells in ACS patients receiving percutaneous coronary intervention (PCI). Blood Th1, Th2, Th17 and Treg cells were detected in 160 ACS patients before PCI, after PCI, at 1 month (M). Short physical performance battery (SPPB) at M1/M3 and major adverse cardiac event (MACE) during follow-ups were evaluated. Th1 and Th17 both showed upward trends during PCI, then greatly declined at M1 (P < 0.001). Th2 exhibited an upward trend during PCI but decreased slightly at M1 (P < 0.001). Treg remained stable during PCI but elevated at M1 (P < 0.001). Moreover, a positive correlation between Th1 and Th17, a negative correlation between Th17 and Treg, were discovered at several timepoints (most P < 0.050). Interestingly, the receiver operating curve (ROC) analyses revealed that Th1 [area under curve (AUC) between 0.633-0.645] and Th17 (AUC between 0.626-0.699) exhibited values estimating SPPB score <= 6 points at M1 or M3 to some extent. Importantly, Th1 (AUC between 0.708-0.710), Th17 (AUC between 0.694-0.783), and Treg (AUC between 0.706-0.729) predicted MACE risk. Multivariate models involving Th and Treg cells along with other characteristics revealed acceptable values estimating SPPB score <= 6 points at M1 or M3 (AUC between 0.690-0.813), and good values predicting MACE risk (AUC between 0.830-0.971). Dynamic variations in Th and Treg cells can predict the prognosis of ACS patients receiving PCI.

Role of neutrophil extracellular trap and immune infiltration in atherosclerotic plaque instability: Novel insight from bioinformatics analysis and machine learning

The instability of atherosclerotic plaques increases the risk of acute coronary syndrome. Neutrophil extracellular traps (NETs), mesh-like complexes consisting of extracellular DNA adorned with various protein substances, have been recently discovered to play an essential role in atherosclerotic plaque formation and development. This study aimed to investigate novel diagnostic biomarkers that can identify unstable plaques for early distinction and prevention of plaque erosion or disruption. Differential expression analysis was used to identify the differentially expressed NET-related genes, and Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were performed. We filtered the characteristic genes using machine learning and estimated diagnostic efficacy using receiver operating characteristic curves. Immune infiltration was detected using single-sample gene set enrichment analysis and the biological signaling pathways involved in characteristic genes utilizing gene set enrichment analysis were explored. Finally, miRNAs- and transcription factors-target genes networks were established. We identified 8 differentially expressed NET-related genes primarily involved in immune-related pathways. Four were identified as capable of distinguishing unstable plaques. More immune cells infiltrated unstable plaques than stable plaques, and these cells were predominantly positively related to characteristic genes. These 4 diagnostic genes are involved in immune responses and the modulation of smooth muscle contractility. Several miRNAs and transcription factors were predicted as upstream regulatory factors, providing further information on the identification and prevention of atherosclerotic plaques rupture. We identified several promising NET-related genes (AQP9, C5AR1, FPR3, and SIGLEC9) and immune cell subsets that may identify unstable atherosclerotic plaques at an early stage and prevent various complications of plaque disruption.

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.

Neutrophil Extracellular Traps in Atherosclerosis and Thrombosis

Despite effective therapeutic and preventive strategies, atherosclerosis and its complications still represent a substantial health burden. Leukocytes and inflammatory mechanisms are increasingly recognized as drivers of atherosclerosis. Neutrophil granulocytes within the circulation were recently shown to undergo neutrophil extracellular trap (NET) formation, linking innate immunity with acute complications of atherosclerosis. In this chapter, we summarize mechanisms of NET formation, evidence for their involvement in atherosclerosis and thrombosis, and potential therapeutic regimens specifically targeting NET components.

The potential targets in immunotherapy of atherosclerosis

Cardiovascular disease is the most common cause of death, which has the highest mortality rate worldwide. Although a diverse range of inflammatory diseases can affect the cardiovascular system, however, heart failure and stroke occur due to atherosclerosis. Atherosclerosis is a chronic autoinflammatory disease of small to large vessels in which different immune mediators are involved in lipid plaque formation and inflammatory vascular remodeling process. A better understanding of the pathophysiology of atherosclerosis may lead to uncovering immunomodulatory therapies. Despite present diagnostic and therapeutic methods, the lack of immunotherapy in the prevention and treatment of atherosclerosis is perceptible. In this review, we will discuss the promising immunological-based therapeutics and novel preventive approaches for atherosclerosis. This study could provide new insights into a better perception of targeted therapeutic pathways and biological therapies.

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.

Immunity in Atherosclerosis: Focusing on T and B Cells

Atherosclerosis is the major cause of the development of cardiovascular disease, which, in turn, is one of the leading causes of mortality worldwide. From the point of view of pathogenesis, atherosclerosis is an extremely complex disease. A huge variety of processes, such as violation of mitophagy, oxidative stress, damage to the endothelium, and others, are involved in atherogenesis; however, the main components of atherogenesis are considered to be inflammation and alterations of lipid metabolism. In this review, we want to focus on inflammation, and more specifically on the cellular elements of adaptive immunity, T and B cells. It is known that various T cells are widely represented directly in atherosclerotic plaques, while B cells can be found, for example, in the adventitia layer. Of course, such widespread and well-studied cells have attracted attention as potential therapeutic targets for the treatment of atherosclerosis. Various approaches have been developed and tested for their efficacy.

T-Cell Molecular Modulation Responses in Atherosclerosis Anergy

Atherosclerosis continues to be a major cause of death in patients with cardiovascular diseases. The cooperative role of immunity has been recently considered in atherosclerotic plaque inflammation, especially adaptive immune response by T cells. In this review, we examine the possible role of T cells in atherosclerosis-mediated inflammation and conceivable therapeutic strategies that can ameliorate complications of atherosclerosis. The cytokines secreted by T-lymphocyte subsets, different pathophysiological profiles of microRNAs (miRs), and the growth factor/receptor axis have diverse effects on the inflammatory cycle of atherosclerosis. Manipulation of miRNA expression and prominent growth factor receptors involved in inflammatory cytokine secretion in atherosclerosis can be considered diagnostic biomarkers in the induction of anergy and blockade of atherosclerotic development. This manuscript reviews immunomodulation of T cells responses in atherosclerosis anergy.

Senescence-induced inflammation: an important player and key therapeutic target in atherosclerosis

Inflammation is a hallmark and potent driver of pathological vascular remodelling in atherosclerosis. However, current anti-inflammatory therapeutic strategies have shown mixed results. As an alternative perspective on the conundrum of chronic inflammation emerging evidence points towards a small subset of senescent cells as a critical player and central node driving atherosclerosis. Senescent cells belonging to various cell types are a dominant and chronic source of a large array of pro-inflammatory cytokines and various additional plaque destabilizing factors, being involved with various aspects of atherosclerosis pathogenesis. Antagonizing these key agitators of local chronic inflammation and plaque instability may provide a causative and multi-purpose therapeutic strategy to treat atherosclerosis. Anti-senescence treatment options with translational potential are currently in development. However, several questions and challenges remain to be addressed before these novel treatment approaches may enter the clinical setting.

Platelet-derived extracellular vesicles to target plaque inflammation for effective anti-atherosclerotic therapy

Atherosclerosis is a kind of chronic inflammatory diseases characterized by dysfunction of local immune responses. Here we engineer platelet-derived extracellular vesicles (PEVs) to load MCC950, an NLRP3-inflammasome inhibitor, for atherosclerosis-targeted therapy. PEVs which are readily collected from the activated platelets selectively bind multiple cell types associated with the formation of atherosclerotic plaque in vivo. Intravenous administration of MCC950-PEVs could significantly reduce the formation of atherosclerotic plaques, lower the local inflammation and inhibit proliferation of macrophages and T cells at the plaque site compared with free drug administration in ApoE-KO mice. Our strategy suggests the promise of PEVs for targeted drug delivery for treatment of atherosclerosis.

Association of Major Histocompatibility Complex Class I Related Chain A/B Positive Microparticles with Acute Myocardial Infarction and Disease Severity

Background: Various cell types undergo activation and stress during atherosclerosis resulting in the development of acute myocardial infarction (AMI) in coronary artery disease (CAD). Major histocompatibility complex class I related chain A and B (MICA/B) can be expressed on the surface of activated and stressed cells and released into blood circulation in several forms including microparticles (MICA/B⁺ MPs) from various cell types. We aimed to investigate the association of these MICA/B⁺ MPs with the presence of AMI. Fifty-one AMI and 46 age-matched control subjects were recruited. Methods: Levels of MICA/B⁺ MPs derived from various parent cells including endothelial cells, platelets, monocytes, neutrophils, and T lymphocytes were determined by flow cytometry. Results: The levels and proportion of MICA/B⁺ MPs from all types of cell origin were significantly increased in AMI patients compared to those of the controls. A multivariate regression model showed an independent association between MICA/B⁺ MPs and AMI (OR = 11.6; 95% CI = 2.8, 47.3). Interestingly, based on the disease severity, we found that the levels of MICA/B⁺ MPs were significantly elevated in the ST-segment elevation myocardial infarction (STEMI) compared to the non-STEMI (NSTEMI) patients. Moreover, an independent association of MICA/B⁺ MPs with the occurrence of STEMI was also demonstrated (OR = 4.1; 95% CI = 1.5, 16.7). Conclusions: These results suggest that MICA/B⁺ MPs are associated with AMI and disease severity. They may act as mediators contributing to the pathological process of AMI. Alternatively, they are the results of various cell activations contributing to AMI.

Immune and Inflammation in Acute Coronary Syndrome: Molecular Mechanisms and Therapeutic Implications

Acute coronary syndrome (ACS) is a major cause of acute death worldwide. Both innate and adaptive immunity regulate atherosclerosis progression, plaque stability, and thrombus formation. Immune and inflammation dysfunction have been indicated in the pathogenesis of ACS. The imbalance in the proatherogenic and antiatherogenic immune networks promotes the transition of plaques from a stable to unstable state and results in the occurrence of acute coronary events. The residual inflammatory risk (RIR) has received increasing attention in recent years, and lowering RIR has been expected to improve the outcomes of ACS patients. The CANTOS, COLCOT, and LoDoCo trials verified the benefits of reducing cardiovascular events using anti-inflammation therapies; however, most of the other studies focusing on lowering RIR produced negative or contradicting results. Therefore, restoring the balance in autoimmune regulation is essential because proatherogenic and antiatherogenic immunomodulatory effects are equally important in the complex human immune network. In this review, we summarized the recent evidence of the roles of proatherogenic and antiatherogenic immune networks in the pathogenesis of ACS and discussed how immune and inflammation contribute to atherosclerosis progression, plaque instability, and adverse cardiovascular events. We also provide a “from bench to bedside” perspective of a novel and promising personalized strategy in RIR intervention and therapeutic approaches for the treatment of ACS.

Interleukin-7 and interleukin-15 drive CD4+CD28null T lymphocyte expansion and function in patients with acute coronary syndrome

AIMS

Inflammation has important roles in atherosclerosis. CD4+CD28null (CD28null) T cells are a specialized T lymphocyte subset that produce inflammatory cytokines and cytotoxic molecules. CD28null T cells expand preferentially in patients with acute coronary syndrome (ACS) rather than stable angina and are barely detectable in healthy subjects. Importantly, ACS patients with CD28null T-cell expansion have increased risk for recurrent acute coronary events and poor prognosis, compared to ACS patients in whom this cell subset does not expand. The mechanisms regulating CD28null T-cell expansion in ACS remain elusive. We therefore investigated the role of cytokines in CD28null T-cell expansion in ACS.

METHODS AND RESULTS

High-purity sorted CD4+ T cells from ACS patients were treated with a panel of cytokines (TNF-α, IL-1β, IL-6, IL-7, and IL-15), and effects on the number, phenotype, and function of CD28null T cells were analysed and compared to the control counterpart CD28+ T-cell subset. IL-7- and IL-15-induced expansion of CD28null T cells from ACS patients, while inflammatory cytokines TNF-α, IL-1β, and IL-6 did not. The mechanisms underlying CD28null T-cell expansion by IL-7/IL-15 were preferential activation and proliferation of CD28null T cells compared to control CD28+ T cells. Additionally, IL-7/IL-15 markedly augmented CD28null T-cell cytotoxic function and interferon-γ production. Further mechanistic analyses revealed differences in baseline expression of component chains of IL-7/IL-15 receptors (CD127 and CD122) and increased baseline STAT5 phosphorylation in CD28null T cells from ACS patients compared to the control CD28+ T-cell subset. Notably, we demonstrate that CD28null T-cell expansion was significantly inhibited by Tofacitinib, a selective JAK1/JAK3 inhibitor that blocks IL-7/IL-15 signalling.

CONCLUSION

Our novel data show that IL-7 and IL-15 drive the expansion and function of CD28null T cells from ACS patients suggesting that IL-7/IL-15 blockade may prevent expansion of these cells and improve patient outcomes.

Atheroprotective nasal immunization with a heat shock protein 60 peptide from Porphyromonas gingivalis

Purpose

Immunization with Porphyromonas gingivalis heat shock protein 60 (PgHSP60) may have an immunoregulatory effect on atherogenesis. The aim of this study was to determine whether nasal immunization with a PgHSP60 peptide could reduce atherosclerotic plaque formation in apolipoprotein E knockout (ApoE KO) mice.

Methods

Seven-week-old male ApoE KO mice were assigned to receive a normal diet, a Western diet, a Western diet and challenge with PgHSP60-derived peptide 14 (Pep14) or peptide 19 (Pep19), or a Western diet and immunization with Pep14 or Pep19 before challenge with Pep14 or Pep19.

Results

Atherosclerotic plaques were significantly smaller in mice that received a Western diet with Pep14 nasal immunization than in mice that received a Western diet and no Pep14 immunization with or without Pep14 challenge. An immunoblot profile failed to detect serum reactivity to Pep14 in any of the study groups. Stimulation by either Pep14 or Pep19 strongly promoted the induction of CD4⁺CD25⁺forkhead box P3 (FoxP3)⁺ human regulatory T cells (Tregs) in vitro. However, the expression of mouse splenic CD4⁺CD25⁺FoxP3⁺ Tregs was lower in the Pep14-immunized mice than in the Pep14-challenged or Pep19-immunized mice. Levels of serum interferon gamma (IFN-γ) and transforming growth factor beta were higher and levels of interleukin (IL) 10 were lower in the Pep14-immunized mice than in the other groups. Induction of CD25⁻ IL-17⁺ T helper 17 (Th17) cells was attenuated in the Pep14-immunized mice.

Conclusions

Nasal immunization with Pep14 may be a mechanism for attenuating atherogenesis by promoting the secretion of IFN-γ and/or suppressing Th17-mediated immunity.

E3 Ubiquitin Ligases as Immunotherapeutic Target in Atherosclerotic Cardiovascular Disease

Chronic low-grade inflammation drives atherosclerosis and despite optimal pharmacological treatment of classical cardiovascular risk factors, one third of the patients with atherosclerotic cardiovascular disease has elevated inflammatory biomarkers. Additional anti-inflammatory strategies to target this residual inflammatory cardiovascular risk are therefore required. T-cells are a dominant cell type in human atherosclerotic lesions. Modulation of T-cell activation is therefore a potential strategy to target inflammation in atherosclerosis. Ubiquitination is an important regulatory mechanism of T-cell activation and several E3 ubiquitin ligases, including casitas B-lineage lymphoma proto-oncogene B (Cbl-B), itchy homolog (Itch), and gene related to anergy in lymphocytes (GRAIL), function as a natural brake on T-cell activation. In this review we discuss recent insights on the role of Cbl-B, Itch, and GRAIL in atherosclerosis and explore the therapeutic potential of these E3 ubiquitin ligases in cardiovascular medicine.

Anti-inflammatory effects of non-statin low-density lipoprotein cholesterol-lowering drugs: an unused potential?

Objectives. Inflammatory responses are closely knit with low-density lipoprotein (LDL)-cholesterol in driving atherosclerosis. Even if LDL-cholesterol is causative to atherosclerotic diseases and LDL-cholesterol lowering reduces hard clinical endpoints, there is a residual risk for clinical events, possibly driven by inflammatory processes, in accordance with its role in autoimmune diseases. Design. As LDL-cholesterol treatment targets are reduced, the use of non-statin lipid-lowering drugs will probably increase. Atherosclerotic plaques evolve through lipid infiltration and modification in the intima, furthermore infiltration of cells including monocytes, macrophages, T-lymphocytes and neutrophils initiating inflammatory signaling. Here we briefly review inflammation in atherosclerosis and the effects of the non-statin lipid-lowering drugs on inflammation. The review is limited to the most common non-statin lipid lowering drugs, i.e. proprotein convertase subtilisin-kexin type 9 (PCSK9) inhibitors, bile acid sequestrants (BAS) and cholesterol absorption inhibitors. Results. PCSK9 inhibition is mostly studied together with statins and is associated with a reduction of pro-inflammatory cytokines. Furthermore, PCSK9 inhibitors seem to have an effect on monocyte migration trough CCR2. They also have an interaction with sirtuins, possibly offering a therapeutic target. BAS have several interesting effects on inflammation, including reduction of pro-inflammatory cytokines and a reduction of the number of infiltrating macrophages, however there are relatively few reports considering that these drugs have been on the market for decades. Ezetimibe also has effects on inflammation including reduction of pro-inflammatory cytokines and adhesion molecules, however these effects are usually accomplished in tandem with statins. Conclusion. This topic adds an interesting piece to the puzzle of atherosclerosis, indicating that PCSK9 inhibition, BAS and ezetimibe all affect thromboinflammation.

Low Levels of CD4 + CD28 null T Cells at Baseline Are Associated With First-Time Coronary Events in a Prospective Population-Based Case-Control Cohort

Objective:

CD4 + CD28 null T cells have been shown to be associated with recurrent coronary events and suggested as potential biomarker and therapeutic target. It is unknown whether CD4 + CD28 null T cells associate with first-time cardiovascular events. We examined CD4 + CD28 null T cells in a prospective population-based cohort and in patients with advanced atherosclerosis.

Approach and Results:

CD4 + CD28 null T cells were quantified in 272 individuals experiencing a first-time coronary event during up to 17 years of follow-up and 272 age- and sex-matched controls in a case-control study, nested within the population-based Malmö Diet and Cancer study. The highest tertile of CD4 + CD28 null T cells was associated with a lower incidence of first-time coronary events compared with the lowest tertile (odds ratio, 0.48 [95% CI, 0.29–0.79], P =0.004) when adjusting for Framingham risk factors. This association remained significant for events recorded after >9 years of follow-up, when most coronary events occurred, but not during the first 9 years of follow-up, despite similar odds ratio. Additionally, we analyzed CD4 + CD28 null T cells in 201 patients with advanced atherosclerosis undergoing carotid endarterectomy. The adjusted hazard ratio for cardiovascular events in patients with advanced atherosclerosis was 2.11 (95% CI, 1.10–4.05, P =0.024), comparing the highest with the lowest CD4 + CD28 null T-cell tertile.

Conclusions:

Our findings reveal complex associations between CD4 + CD28 null T cells and cardiovascular disease. Although we confirm the reported positive associations with an adverse prognosis in patients with already established disease, the opposite associations with first-time coronary events in the population-based cohort may limit the clinical use of CD4 + CD28 null T cells.

Type 1 diabetic mellitus patients with increased atherosclerosis risk display decreased CDKN2A/2B/2BAS gene expression in leukocytes

Background

Type 1 diabetes mellitus (T1DM) patients display increased risk of cardiovascular disease (CVD) and are characterized by a diminished regulatory T (Treg) cell content or function. Previous studies have shown an association between decreased CDKN2A/2B/2BAS gene expression and enhanced CVD. In the present study the potential relationship between CDKN2A/2B/2BAS gene expression, immune cell dysfunction and increased cardiovascular risk in T1DM patients was explored.

Methods

A cross-sectional study was performed in 90 subjects divided into controls and T1DM patients. Circulating leukocyte subpopulations analysis by flow cytometry, expression studies on peripheral blood mononuclear cell by qPCR and western blot and correlation studies were performed in both groups of subjects.

Results

Analysis indicated that, consistent with the described T cell dysfunction, T1DM subjects showed decreased circulating CD4+CD25+CD127− Treg cells. In addition, T1DM subjects had lower mRNA levels of the transcription factors FOXP3 and RORC and lower levels of IL2 and IL6 which are involved in Treg and Th17 cell differentiation, respectively. T1DM patients also exhibited decreased mRNA levels of CDKN2A (variant 1 p16^Ink4a), CDKN2A (p14^Arf,variant 4), CDKN2B (p15^Ink4b) and CDKN2BAS compared with controls. Notably, T1DM patients had augmented pro-atherogenic CD14++CD16+-monocytes, which predict cardiovascular acute events and enhanced common carotid intima-media thickness (CC-IMT).

Conclusions

Decreased expression of CDKN2A/2B/2BAS in leukocytes associates with increased CC-IMT atherosclerosis surrogate marker and proatherogenic CD14++CD16+ monocytes in T1DM patients. These results suggest a potential role of CDKN2A/2B/2BAS genes in CVD risk in T1DM.

Electronic supplementary material

The online version of this article (10.1186/s12967-019-1977-1) contains supplementary material, which is available to authorized users.

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.

Potential Applications of Remote Limb Ischemic Conditioning for Chronic Cerebral Circulation Insufficiency

Chronic cerebral circulation insufficiency (CCCI) refers to a chronic decrease in cerebral blood perfusion, which may lead to cognitive impairment, psychiatric disorders such as depression, and acute ischemic stroke. Remote limb ischemic conditioning (RLIC), in which the limbs are subjected to a series of transient ischemic attacks, can activate multiple endogenous protective mechanisms to attenuate fatal ischemic injury to distant organs due to acute ischemia, such as ischemic stroke. Recent studies have also reported that RLIC can alleviate dysfunction in distant organs caused by chronic, non-fatal reductions in blood supply (e.g., CCCI). Indeed, research has indicated that RLIC may exert neuroprotective effects against CCCI through a variety of potential mechanisms, including attenuated glutamate excitotoxicity, improved endothelial function, increased cerebral blood flow, regulation of autophagy and immune responses, suppression of apoptosis, the production of protective humoral factors, and attenuated accumulation of amyloid-β. Verification of these findings is necessary to improve prognosis and reduce the incidence of acute ischemic stroke/cognitive impairment in patients with CCCI.

Changes in CDKN2A/2B expression associate with T-cell phenotype modulation in atherosclerosis and type 2 diabetes mellitus

Previous studies indicate a role of CDKN2A/2B/2BAS genes in atherosclerosis and type 2 diabetes mellitus (T2DM). Progression of these diseases is accompanied by T-cell imbalance and chronic inflammation. Our main objective was to investigate a potential association between CDKN2A/2B/2BAS gene expression and T cell phenotype in T2DM and coronary artery disease (CAD) in humans, and to explore the therapeutic potential of these genes to restore immune cell homeostasis and disease progression. Reduced mRNA levels of CDKN2A (p16^Ink4a), CDKN2B (p15^Ink4b), and CDKN2BAS were observed in human T2DM and T2DM-CAD subjects compared with controls. Protein levels of p16^Ink4a and p15^Ink4b were also diminished in T2DM-CAD patients while CDK4 levels, the main target of p16^Ink4a and p15^Ink4b, were augmented in T2DM and T2DM-CAD subjects. Both patient groups displayed higher activated CD3+CD69+ T cells and proatherogenic CD14++CD16+ monocytes, while CD4+CD25+CD127 regulatory T (Treg cells) cells were decreased. Treatment of primary human lymphocytes with PD0332991, a p16^Ink4a/p15^Ink4b mimetic drug and a proven CDK4 inhibitor, increased Treg cells and the levels of activated transcription factor phosphoSTAT5. In vivo PD0332991 treatment of atherosclerotic apoE-/- mice and insulin resistant apoE-/-Irs2+/- mice augmented Foxp3-expressing Treg cells and decreased lesion size. Thus, atherosclerosis complications in T2DM associate with altered immune cell homeostasis, diminished CDKN2A/2B/2BAS expression, and increased CDK4 levels. The present study also suggests that the treatment with drugs that mimic CDKN2A/2B genes could potential be considered as a promising therapy to delay atherosclerosis.

Interactions between dyslipidemia and the immune system and their relevance as putative therapeutic targets in atherosclerosis

Cardiovascular disease (CVD) continues to be a leading cause of death worldwide with atherosclerosis being the major underlying pathology. The interplay between lipids and immune cells is believed to be a driving force in the chronic inflammation of the arterial wall during atherogenesis. Atherosclerosis is initiated as lipid particles accumulate and become trapped in vessel walls. The subsequent immune response, involving both adaptive and immune cells, progresses plaque development, which may be exacerbated under dyslipidemic conditions. Broad evidence, especially from animal models, clearly demonstrates the effect of lipids on immune cells from their development in the bone marrow to their phenotypic switching in circulation. Interestingly, recent research has also shown a long-lasting epigenetic signature from lipids on immune cells. Traditionally, cardiovascular therapies have approached atherosclerosis through lipid-lowering medications because, until recently, anti-inflammatory therapies have been largely unsuccessful in clinical trials. However, the recent Canakinumab Antiinflammatory Thrombosis Outcomes Study (CANTOS) provided pivotal support of the inflammatory hypothesis of atherosclerosis in man spurring on anti-inflammatory strategies to treat atherosclerosis. In this review, we describe the interactions between lipids and immune cells along with their specific outcomes as well as discuss their future perspective as potential cardiovascular targets.

CD28null pro-atherogenic CD4 T-cells explain the link between CMV infection and an increased risk of cardiovascular death

An increased risk of cardiovascular death in Cytomegalovirus (CMV)-infected individuals remains unexplained, although it might partly result from the fact that CMV infection is closely associated with the accumulation of CD28^null T-cells, in particular CD28^null CD4 T-cells. These cells can directly damage endothelium and precipitate cardiovascular events. However, the current paradigm holds that the accumulation of CD28^null T-cells is a normal consequence of aging, whereas the link between these T-cell populations and CMV infection is explained by the increased prevalence of this infection in older people. Resolving whether CMV infection or aging triggers CD28^null T-cell expansions is of critical importance because, unlike aging, CMV infection can be treated.

Methods: We used multi-color flow-cytometry, antigen-specific activation assays, and HLA-typing to dissect the contributions of CMV infection and aging to the accumulation of CD28^null CD4 and CD8 T-cells in CMV+ and CMV- individuals aged 19 to 94 years. Linear/logistic regression was used to test the effect of sex, age, CMV infection, and HLA-type on CD28^null T-cell frequencies.

Results: The median frequencies of CD28^null CD4 T-cells and CD28^null CD8 T-cells were >12-fold (p=0.000) but only approximately 2-fold higher (p=0.000), respectively, in CMV+ (n=136) compared with CMV- individuals (n=106). The effect of CMV infection on these T-cell subsets was confirmed by linear regression. Unexpectedly, aging contributed only marginally to an increase in CD28^null T-cell frequencies, and only in CMV+ individuals. Interestingly, the presence of HLA-DRB1*0301 led to an approximately 9-fold reduction of the risk of having CD28^null CD4 T-cell expansions (OR=0.108, p=0.003). Over 75% of CMV-reactive CD4 T-cells were CD28^null.

Conclusion: CMV infection and HLA type are major risk factors for CD28^null CD4 T-cell-associated cardiovascular pathology. Increased numbers of CD28^null CD8 T-cells are also associated with CMV infection, but to a lesser extent. Aging, however, makes only a negligible contribution to the expansion of these T-cell subsets, and only in the presence of CMV infection. Our results open up new avenues for risk assessment, prevention, and treatment.

Regulatory T cells as a new therapeutic target for atherosclerosis

Atherosclerosis is an autoimmune disease caused by self- and non-self-antigens contributing to excessive activation of T and B cell immune responses. These responses further aggravate vascular infiammation and promote progression of atherosclerosis and vulnerability to plaques via releasing pro-infiammatory cytokines. Regulatory T cells (Tregs) as the major immunoregulatory cells, in particular, induce and maintain immune homeostasis and tolerance by suppressing the immune responses of various cells such as T and B cells, natural killer (NK) cells, monocytes, and dendritic cells (DCs), as well as by secreting inhibitory cytokines interleukin (IL)-10, IL-35 and transcription growth factor β (TGF-β) in both physiological and pathological states. Numerous evidence demonstrates that reduced numbers and dysfunction of Treg may be involveved in atherosclerosis pathogenesis. Increasing or restoring the numbers and improving the immunosuppressive capacity of Tregs may serve as a fundamental immunotherapy to treat atherosclerotic cardiovascular diseases. In this article, we briefiy present current knowledge of Treg subsets, summarize the relationship between Tregs and atherosclerosis development, and discuss the possibilities of regulating Tregs for prevention of atherosclerosis pathogenesis and enhancement of plaque stability. Although the exact molecular mechanisms of Treg-mediated protection against atherosclerosis remain to be elucidated, the strategies for targeting the regulation of Tregs may provide specific and significant approaches for the prevention and treatment of atherosclerotic cardiovascular diseases.

CD4+CD28null T Lymphocytes are Associated with the Development of Atrial Fibrillation after Elective Cardiac Surgery

Post-operative atrial fibrillation (POAF) is postulated as a complex interaction of different pathogenic factors, suggesting inflammatory processes as a main trigger of this particular type of atrial fibrillation. Therefore, the study sought to assess the impact of cellular immunity on the development of POAF. Comparing patients developing POAF to individuals free of POAF the fraction of CD4⁺CD28^null T Lymphocytes was significantly higher in individuals developing POAF (11.1% [POAF] vs. 1.9% [non-POAF]; p < 0.001). CD4⁺CD28^null cells were independently associated with the development of POAF with an adjusted odds ratio per one standard deviation of 4.89 (95% CI: 2.68–8.97; p < 0.001). Compared to N-terminal Pro-Brain Natriuretic Peptide, the fraction of CD4⁺CD28^null cells demonstrated an increased discriminatory power for the development of POAF (NRI: 87.9%, p < 0.001; IDI: 30.9%, p < 0.001). Interestingly, a pre-operative statin-therapy was associated with a lower fraction of CD4⁺CD28^null cells (p < 0.001) and showed an inverse association with POAF (p < 0.001). CD4⁺CD28^null cells proved to be predictive for the development of POAF after cardiac surgery. Our results potentially indicate an auto-immune impact of this preexisting, highly cytotoxic T cell subset in the pathogenesis of POAF, which might be modified via the anti-inflammatory potential of a pre-operative statin-therapy.