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

Causal relationship between circulating inflammatory proteins and atherosclerosis: a bidirectional Mendelian randomization study and meta-analysis

BACKGROUND

Atherosclerosis (AS) is a chronic inflammatory disease that significantly contributes to cardiovascular morbidity and mortality. Despite extensive research efforts, the connections between circulating inflammatory proteins (CIPs) and different subtypes of AS remain poorly understood. This study aims to clarify these relationships through Mendelian randomization (MR) analysis.

METHODS

We utilized summary statistics from genome-wide association studies (GWAS) that included 14,824 European participants to analyze inflammatory protein levels, alongside data from the IEU GWAS database for AS phenotypes. Our primary approach for MR analysis was the inverse variance weighted method. To ensure the validity and robustness of the causal relationships, we conducted tests for pleiotropy and heterogeneity, as well as reverse MR analysis to assess the possibility of reverse causality. Finally, we performed a meta-analysis to consolidate and interpret our findings comprehensively.

RESULTS

Our MR analysis identified several significant associations: elevated artemin [odds ratio (OR) = 1.195], glial cell line-derived neurotrophic factor (hGDNF) (OR = 1.173), and tumor necrosis factor (TNF) (OR = 1.179) levels increased peripheral atherosclerosis (PA) risk; higher CUB domain-containing protein 1 (OR = 0.534), interleukin (IL)-8 (OR = 0.274), monocyte chemoattractant protein-3 (OR = 0.373), transforming growth factor-alpha (OR = 0.306), and tumor necrosis factor receptor superfamily member 9 (OR = 0.423) levels decreased cerebral artery atherosclerosis risk; fibroblast growth factor 21 (FGF-21) (OR = 1.122), hGDNF (OR = 1.108), and IL-22 receptor subunit alpha-1 (IL-22RA1) (OR = 1.235) levels were positively associated with coronary artery atherosclerosis (COA) risk; while IL-13 (OR = 0.909) and TNF-beta levels (OR = 0.954) were negatively associated with COA risk. C-X-C motif chemokine 6 levels (CXCL6) (OR = 1.353) and hGDNF (OR = 1.161) were identified as risk factors for atherosclerosis, excluding cerebral, coronary, and peripheral arterial disease (AECCP). In contrast, IL-2 receptor subunit beta levels (OR = 0.801) and IL-6 levels (OR = 0.788) were found to be protective factors for AECCP. Additionally, CXCL6 (OR = 1.261), FGF-21 (OR = 1.090), IL-22RA1 (OR = 1.127), and hGDNF (OR = 1.134) exhibited a risk effect against overall AS risk, while IL-6 (OR = 0.834) exhibited a protective effect against overall AS risk.

CONCLUSIONS

This study identifies specific CIPs that have significant causal effects on various forms of AS through MR analysis. The findings suggest potential biomarkers and treatment targets for preventing and managing different manifestations of AS in clinical practice.

Current anti-inflammatory strategies for treatment of heart failure: From innate to adaptive immunity

Cardiovascular disease (CVD) is the leading cause of death in developed countries worldwide, often manifesting in the form of heart failure (HF). Recent successful clinical outcomes of anti-inflammatory therapies in HF patients have greatly boosted interest in basic and translational research on the role of inflammation in development of HF. In this review, we discuss recent and ongoing therapies targeting inflammation in CVD/HF, including broad-spectrum anti-inflammatory drugs, supplements, and biologicals such as canakinumab and anakinra. We also discuss the growing body of literature supporting off-target/anti-inflammatory actions of mainline CVD/HF agents, including guideline-directed medical therapy (GDMT) drugs that target the neurohormonal axis, and statins. We discuss therapeutics that target autoimmune mechanisms, and their implications for treating patients with autoimmune diseases with HF or at-risk of developing HF. We also discuss recent evidence for vaccines in modulating the immune response during HF. We conclude that despite the wealth of knowledge gained in the past decade, the therapeutic efficacy of anti-inflammatory therapy is driven by many biological and logistical factors that vary from patient to patient. Furthermore, more studies are needed to understand the adaptive/autoimmune component of HF, particularly in women and patients with pre-existing autoimmune disease. As the number of patients with HF patients who suffer from obesity, diabetes, or autoimmune disease continues to grow, our understanding of inflammation must continue to evolve to reflect these underlying co-morbidities.

Anti-inflammatory phenotypes of immune cells after myocardial infarction and prospects of therapeutic strategy

Often causing negative cardiac remodeling and heart failure, a major threat to human life and health, myocardial infarction (MI) is a cardiovascular disease with a high morbidity and fatality rate worldwide. Maintaining ordinary heart function depends significantly on the immune system. Necrotic cardiomyocyte signals promote specific immunity and activate general immunity as the disease progresses in MI. Complex immune cells play a key role in all stages of MI progression by removing necrotic cardiomyocytes and tissue and promoting the healing of damaged tissue cells. Immune cells can help to regrow injured heart muscle as well as enable both inflammation and cardiomyocyte death. Immune cells are essential elements that help the immune system carry out its protective function. There are two types of immunity: nonspecific immunity and specific immunity. Developed throughout the long-term evolution of species, nonspecific immunity (including macrophages, myeloid-derived suppressor cells MDSC, natural killer cells NK, neutrophils, and dendritic cells DC) offers immediate and conservative host defense that might destroy healthy tissues because of its nonspecific nature. Precisely acquired immunity, specific immunity helps humoral and cellular immunity mediated through B and T cells correspondingly. These findings offer crucial information needed for the creation of effective immunomodulatory treatment, as discussed in this article.

Regulatory T cells: a promising new therapeutic target in ventricular remodeling after myocardial infarction

Myocardial infarction (MI) is one of the leading causes of death worldwide. It is triggered by thrombosis or vascular occlusion. After MI, damaged cardiomyocytes are replaced by scar tissue, leading to systolic and diastolic dysfunction, followed by adverse remodeling. Regulatory T cells (Tregs), as major immune cells, play a crucial role in post-MI inflammation and immunomodulation. Tregs improve cardiac remodeling after MI through various mechanisms, including inhibiting inflammatory cell infiltration, inducing anti-inflammatory macrophages, suppressing cell apoptosis, regulating fibroblast function, and promoting angiogenesis. The modulation of Tregs number or function may provide novel methods for improving post-MI remodeling. This review describes the immunoregulatory roles of Tregs, their regulatory mechanisms in post-MI ventricular remodeling, and the prospects and challenges for clinical application. However, the exact molecular mechanisms of Tregs in ventricular remodeling remain to be investigated. Although most of the current studies are at the preclinical stage, they hold great potential for further application in the future.

Inflammation in coronary atherosclerosis: diagnosis and treatment

Coronary atherosclerosis is a chronic condition characterised by the development of an atherosclerotic plaque in the inner layer of the coronary artery, mainly associated with cholesterol accumulation and favoured by endothelial dysfunction related to other cardiovascular risk factors, such as smoking, diabetes and hypertension. A key actor in this process is the systemic inflammatory response, which can make plaques either grow slowly over the course of years (like a 'mountain'), obstructing coronary flow, and causing stable coronary artery disease, or make them explode (like a 'volcano') with subsequent abrupt thrombosis causing an acute coronary syndrome. This central role of inflammation in coronary atherosclerosis has led to its consideration as a modifiable cardiovascular risk factor and a therapeutic target. Classic anti-inflammatory drugs have been tested in clinical trials with some encouraging results, and new drugs specifically designed to tackle inflammation are currently being under investigation in ongoing trials. The objectives of this review are to (1) summarise the role of inflammatory biomarkers and imaging techniques to detect inflammation at each stage of plaque progression, and (2) explore currently available and upcoming anti-inflammatory therapies.

Role of interleukins in the pathogenesis of coronary heart disease: A literature review

Interleukins (ILs), a subset of cytokines, play a critical role in the pathogenesis of coronary heart disease (CHD) by mediating inflammation. This review article summarizes the role of ILs such as IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, and IL-10 in the pathogenesis of CHD. Individuals with mild coronary artery disease (CAD) and angina who have ischemic heart disease have higher serum concentrations of IL-1b. Larger studies are needed to verify the safety and assess the effectiveness of low-dose IL-2 as an anti-inflammatory treatment. IL-3 is found more often in patients receiving coronary angioplasty compared to patients with asymptomatic CAD or without CAD. Serum levels of IL-4 are reliable indicators of CAD. An independent correlation between IL-5 and the incidence of CAD was demonstrated. IL-6 helps serve as a reliable biomarker for the degree of CAD, as determined by the Gensini score, and is a key factor in the development of atherosclerosis. Also, variants of IL-7/7R have been linked to the Han Chinese population's genetic susceptibility to CHD. IL-8 plays a role in the progression of CAD occurrences. By interacting with conventional risk factors for CAD, IL-9 may contribute to the development of CAD and offer an innovative approach to its prevention and management. There was a 34% increased risk of a CHD incident for every standard deviation rise in baseline IL-10 levels.

Anti-inflammatory Therapies for Ischemic Heart Disease

PURPOSE OF REVIEW

The inclusion of immunomodulatory strategies as supportive therapies in ischemic heart disease (IHD) has garnered significant support over recent years. Several such approaches appear to be unified through their ultimate target, the NLRP3 inflammasome. This review presents a brief update on immunomodulatory strategies in the continuum of conditions constituting ischemic heart disease and emphasising on the seemingly unifying mechanism of NLRP3 activation as well as modulation across these conditions.

RECENT FINDINGS

The NLRP3 inflammasome is a multiprotein complex assembled upon inflammatory stimulation, causing the release of pro-inflammatory cytokines and initiating pyroptosis. The NLRP3 pathway is relevant in inflammatory signalling of cardiac immune cells as well as non-immune cells in the myocardium, including cardiomyocytes, fibroblasts and endothelial cells. In addition to a focus on clinical outcome and efficacy trials of targeting NLRP3-related pathways, the potential connection between immunomodulation in cardiology and the NLRP3 pathway is currently being explored in preclinical trials. Colchicine, cytokine-based approaches and SGLT2 inhibitors have emerged as promising agents. However, the conditions comprising IHD including atherosclerosis, coronary artery disease (CAD), myocardial infarction (MI) and ischemic cardiomyopathy/heart failure (iCMP/HF) are not equally amenable to immunomodulation with the respective drugs. Atherosclerosis, coronary artery disease and ischemic cardiomyopathy are affected by chronic inflammation, but the immunomodulatory approach to acute inflammation in the post-MI setting remains a pharmacological challenge, as detrimental and regenerative effects of myocardial inflammation are initiated in unison. The NLRP3 inflammasome lies at the center of cell mediated inflammation in IHD. Recent trial evidence has highlighted anti-inflammatory effects of colchicine, interleukin-based therapy as well as SGLT2i in IHD and that the respective drugs modulate the NLRP3 inflammasome.

The Interplay Between Immunity, Inflammation and Endothelial Dysfunction

The endothelium is pivotal in multiple physiological processes, such as maintaining vascular homeostasis, metabolism, platelet function, and oxidative stress. Emerging evidence in the past decade highlighted the immunomodulatory function of endothelium, serving as a link between innate, adaptive immunity and inflammation. This review examines the regulation of the immune-inflammatory axis by the endothelium, discusses physiological immune functions, and explores pathophysiological processes leading to endothelial dysfunction in various metabolic disturbances, including hyperglycemia, obesity, hypertension, and dyslipidaemia. The final section focuses on the novel, repurposed, and emerging therapeutic targets that address the immune-inflammatory axis in endothelial dysfunction.

Targeting gut microbiota to regulate the adaptive immune response in atherosclerosis

Atherosclerosis, the leading cause of death worldwide, is a chronic inflammatory disease leading to the accumulation of lipid-rich plaques in the intima of large and medium-sized arteries. Accumulating evidence indicates the important regulatory role of the adaptive immune system in atherosclerosis during all stages of the disease. The gut microbiome has also become a key regulator of atherosclerosis and immunomodulation. Whilst existing research extensively explores the impact of the microbiome on the innate immune system, only a handful of studies have explored the regulatory capacity of the microbiome on the adaptive immune system to modulate atherogenesis. Building on these concepts and the pitfalls on the gut microbiota and adaptive immune response interaction, this review explores potential strategies to therapeutically target the microbiome, including the use of prebiotics and vaccinations, which could influence the adaptive immune response and consequently plaque composition and development.

Vaccination as a Promising Approach in Cardiovascular Risk Mitigation: Are We Ready to Embrace a Vaccine Strategy?

Cardiovascular disease (CVD) remains a leading global health concern, with atherosclerosis being its principal cause. Standard CVD treatments primarily focus on mitigating cardiovascular (CV) risk factors through lifestyle changes and cholesterol-lowering therapies. As atherosclerosis is marked by chronic arterial inflammation, the innate and adaptive immune systems play vital roles in its progression, either exacerbating or alleviating disease development. This intricate interplay positions the immune system as a compelling therapeutic target. Consequently, immunomodulatory strategies have gained increasing attention, though none have yet reached widespread clinical adoption. Safety concerns, particularly the suppression of host immune defenses, remain a significant barrier to the clinical application of anti-inflammatory therapies. Recent decades have revealed the significant role of adaptive immune responses to plaque-associated autoantigens in atherogenesis, opening new perspectives for targeted immunological interventions. Preclinical models indicate that vaccines targeting specific atherosclerosis-related autoantigens can slow disease progression while preserving systemic immune function. In this context, numerous experimental studies have advanced the understanding of vaccine development by exploring diverse targeting pathways. Key strategies include passive immunization using naturally occurring immunoglobulin G (IgG) antibodies and active immunization targeting low-density lipoprotein cholesterol (LDL-C) and apolipoproteins, such as apolipoprotein B100 (ApoB100) and apolipoprotein CIII (ApoCIII). Other approaches involve vaccine formulations aimed at proteins that regulate lipoprotein metabolism, including proprotein convertase subtilisin/kexin type 9 (PCSK9), cholesteryl ester transfer protein (CETP), and angiopoietin-like protein 3 (ANGPTL3). Furthermore, the literature highlights the potential for developing non-lipid-related vaccines, with key targets including heat shock proteins (HSPs), interleukins (ILs), angiotensin III (Ang III), and a disintegrin and metalloproteinase with thrombospondin motifs 7 (ADAMTS-7). However, translating these promising findings into safe and effective clinical therapies presents substantial challenges. This review provides a critical evaluation of current anti-atherosclerotic vaccination strategies, examines their proposed mechanisms of action, and discusses key challenges that need to be overcome to enable clinical translation.

Targeting the adaptive immune continuum in atherosclerosis and post-MI injury

Atherosclerotic disease is a cholesterol-rich lipoprotein particle-driven disease resulting in the formation of atherosclerotic plaques in large and medium size arteries. Rupture or erosion of atherosclerotic plaques can trigger the formation of a thrombus causing the obstruction of the blood flow in the coronary artery and thereby leading to myocardial infarction (MI). Inflammation is a crucial pillar of the mechanisms leading to atherosclerosis and governing the cardiac repair post-MI. Dissecting the complex and sophisticated networks of the immune responses underlying the formation of atherosclerotic plaques and affecting the healing of the heart after MI will allow the designing of highly precise immunomodulatory therapies for these settings. Notably, MI also accelerates atherosclerosis via modulating the response of the immune system. Therefore, for the identification of effective and safe therapeutic targets, it is critical to consider the inflammatory continuum that interconnects the two pathologies and identify immunomodulatory strategies that confer a protective effect in both settings or at least, affect each pathology independently. Adaptive immunity, which consists of B and T lymphocytes, is a major regulator of atherosclerosis and post-MI cardiac repair. Here, we review and discuss the effect of potential adaptive immunity-targeting therapies, such as cell-depleting therapies, in atherosclerosis and post-MI cardiac injury.

Erosion of the Atheroma: Wicked T Cells at the Culprit Site

PURPOSE OF REVIEW

There is a growing recognition of plaque erosion as a cause of acute coronary syndrome. This review aims to examine the potential involvement of T cells in this process.

RECENT FINDINGS

Immune-vascular interactions have been identified in the development of plaque erosions. Up to one-third of eroded plaques show evidence of active immune infiltration, with the presence of T cells. We propose that microerosions may frequently occur in association with the infiltration of T cells and macrophages in early atherosclerotic lesions. Healing of erosions could trigger the deposition of excessive extracellular matrix. The pro-inflammatory and cytotoxic actions of T cells, along with reduced endothelial integrity and other mechanisms, may subsequently give rise to clinical symptoms. To gain a better understanding of the role of T cells in plaque erosion, it is crucial to develop improved models for conducting controlled experiments and to study atherosclerosis in younger individuals.

Autoimmune diseases and atherosclerotic cardiovascular disease

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

Precision Medicine in Acute Coronary Syndromes

Nowadays, current guidelines on acute coronary syndrome (ACS) provide recommendations mainly based on the clinical presentation. However, greater attention is being directed to the specific pathophysiology underlying ACS, considering that plaque destabilization and rupture leading to luminal thrombotic obstruction is not the only pathway involved, albeit the most recognized. In this review, we discuss how intracoronary imaging and biomarkers allow the identification of specific ACS endotypes, leading to the recognition of different prognostic implications, tailored management strategies, and new potential therapeutic targets. Furthermore, different strategies can be applied on a personalized basis regarding antithrombotic therapy, non-culprit lesion revascularization, and microvascular obstruction (MVO). With respect to myocardial infarction with non-obstructive coronary arteries (MINOCA), we will present a precision medicine approach, suggested by current guidelines as the mainstay of the diagnostic process and with relevant therapeutic implications. Moreover, we aim at illustrating the clinical implications of targeted strategies for ACS secondary prevention, which may lower residual risk in selected patients.

Moving from lipids to leukocytes: inflammation and immune cells in atherosclerosis

Atherosclerotic cardiovascular disease (ASCVD) is the most important cause of morbidity and mortality worldwide. While it is traditionally attributed to lipid accumulation in the vascular endothelium, recent research has shown that plaque inflammation is an important additional driver of atherogenesis. Though clinical outcome trials utilizing anti-inflammatory agents have proven promising in terms of reducing ASCVD risk, it is imperative to identify novel actionable targets that are more specific to atherosclerosis to mitigate adverse effects associated with systemic immune suppression. To that end, this review explores the contributions of various immune cells from the innate and adaptive immune system in promoting and mitigating atherosclerosis by integrating findings from experimental studies, high-throughput multi-omics technologies, and epidemiological research.

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.

Therapeutic Avenues to Modulate B-Cell Function in Patients With Cardiovascular Disease

The adaptive immune system plays an important role in the development and progression of atherosclerotic cardiovascular disease. B cells can have both proatherogenic and atheroprotective roles, making treatments aimed at modulating B cells important therapeutic targets. The innate-like B-cell response is generally considered atheroprotective, while the adaptive response is associated with mixed consequences for atherosclerosis. Additionally, interactions of B cells with components of the adaptive and innate immune system, including T cells and complement, also represent key points for therapeutic regulation. In this review, we discuss therapeutic approaches based on B-cell depletion, modulation of B-cell survival, manipulation of both the antibody-dependent and antibody-independent B-cell response, and emerging immunization techniques.

T-Cell/B-Cell Interactions in Atherosclerosis

Atherosclerosis is a complex inflammatory disease in which the adaptive immune response plays an important role. While the overall impact of T and B cells in atherosclerosis is relatively well established, we are only beginning to understand how bidirectional T-cell/B-cell interactions can exert prominent atheroprotective and proatherogenic functions. In this review, we will focus on these T-cell/B-cell interactions and how we could use them to therapeutically target the adaptive immune response in atherosclerosis.

Low-dose Interleukin-2 Therapy: Fine-tuning Treg in Solid Organ Transplantation?

Regulatory T cells (Treg), a subset of CD4 + T cells, are potent regulators of immune reactions, which have been shown to be a promising therapeutic alternative to toxic immunosuppressive drugs. Data support the utility of Treg in managing immunopathologies, including solid organ transplant rejection, graft-versus-host disease, and autoimmune disorders. Notably, reports suggest that interleukin-2 (IL-2) is critical to survival of Treg, which constitutively express high levels of CD25, that is, the IL-2 receptor α-chain, and are exquisitely sensitive to IL-2, even at very low concentrations in contrast to effector T cells, which only upregulate IL-2 receptor α-chain on activation. This has led to the notion of using low doses of exogenous IL-2 therapeutically to modulate the immune system, specifically Treg numbers and function. Here, we summarize developments of clinical experience with low-dose IL-2 (LD-IL-2) as a therapeutic agent. So far, no clinical data are available to support the therapeutic use of LD-IL-2 therapy in the solid organ transplant setting. For the latter, fine-tuning by biotechnological approaches may be needed because of the narrow therapeutic window and off-target effects of LD-IL-2 therapy and so to realize the therapeutic potential of this molecule.

Relationship of neutrophil-to-lymphocyte ratio, in addition to C-reactive protein, with cardiovascular events in patients with type 2 diabetes

AIM

To quantify the relationship of neutrophil-to-lymphocyte ratio (NLR) with cardiovascular events and all-cause mortality in patients with type 2 diabetes (T2D), independent of C-reactive protein (CRP).

METHODS

Patients with T2D from the UCC-SMART-cohort were studied using multivariable-adjusted Cox regression. The relationship of NLR and CRP with vascular events (cerebrovascular events, myocardial infarction and vascular death) and all-cause mortality was quantified.

RESULTS

During 10,833 person-years, 232 vascular events and 302 deaths occurred in 1,239 patients with T2D. Risk of vascular events and all-cause mortality increased per standard deviation (SD) in NLR (hazard ratio (HR) 1.27; 95 % confidence interval (CI):1.11-1.46) and 1.15; 95 % CI:1.02-1.30) after adjustment for CRP. CRP was not associated with vascular events after adjustment for NLR, (HR per SD 1.03; 95 % CI: 0.90-1.19), but was associated with all-cause mortality (HR per SD 1.18; 95 % CI: 1.04-1.33). Notably, NLR was related to vascular events in patients with CRP < 2 mg/L (HR per unit 1.45; 95 % CI: 1.19-1.77).

CONCLUSION

In patients with T2D, NLR is related to higher risk of CVD and all-cause mortality, independently from CRP. NLR is related to CVD even when CRP is low, indicating that NLR is a marker of CVD-risk in addition to CRP. Both NLR and CRP are independently related to all-cause mortality in T2D patients.

Adaptive immunity and atherosclerosis: aging at its crossroads

Adaptive immunity plays a profound role in atherosclerosis pathogenesis by regulating antigen-specific responses, inflammatory signaling and antibody production. However, as we age, our immune system undergoes a gradual functional decline, a phenomenon termed "immunosenescence". This decline is characterized by a reduction in proliferative naïve B- and T cells, decreased B- and T cell receptor repertoire and a pro-inflammatory senescence associated secretory profile. Furthermore, aging affects germinal center responses and deteriorates secondary lymphoid organ function and structure, leading to impaired T-B cell dynamics and increased autoantibody production. In this review, we will dissect the impact of aging on adaptive immunity and the role played by age-associated B- and T cells in atherosclerosis pathogenesis, emphasizing the need for interventions that target age-related immune dysfunction to reduce cardiovascular disease risk.

Macrophage profiling in atherosclerosis: understanding the unstable plaque

The development and rupture of atherosclerotic plaques is a major contributor to myocardial infarctions and ischemic strokes. The dynamic evolution of the plaque is largely attributed to monocyte/macrophage functions, which respond to various stimuli in the plaque microenvironment. To this end, macrophages play a central role in atherosclerotic lesions through the uptake of oxidized low-density lipoprotein that gets trapped in the artery wall, and the induction of an inflammatory response that can differentially affect the stability of the plaque in men and women. In this environment, macrophages can polarize towards pro-inflammatory M1 or anti-inflammatory M2 phenotypes, which represent the extremes of the polarization spectrum that include Mhem, M(Hb), Mox, and M4 populations. However, this traditional macrophage model paradigm has been redefined to include numerous immune and nonimmune cell clusters based on in-depth unbiased single-cell approaches. The goal of this review is to highlight (1) the phenotypic and functional properties of monocyte subsets in the circulation, and macrophage populations in atherosclerotic plaques, as well as their contribution towards stable or unstable phenotypes in men and women, and (2) single-cell RNA sequencing studies that have advanced our knowledge of immune, particularly macrophage signatures present in the atherosclerotic niche. We discuss the importance of performing high-dimensional approaches to facilitate the development of novel sex-specific immunotherapies that aim to reduce the risk of cardiovascular events.

Novel therapeutic targets and emerging treatments for atherosclerotic cardiovascular disease

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of morbidity and mortality worldwide. Even with excellent control of low-density lipoprotein cholesterol (LDL-C) levels, adverse cardiovascular events remain a significant clinical problem worldwide, including among those without any traditional ASCVD risk factors. It is necessary to identify novel sources of residual risk and to develop targeted strategies that address them. Lipoprotein(a) has become increasingly recognized as a new cardiovascular risk determinant. Large-scale clinical trials have also signalled the potential additive cardiovascular benefits of decreasing triglycerides beyond lowering LDL-C levels. Since CANTOS (Anti-inflammatory Therapy with Canakinumab for Atherosclerotic Disease) demonstrated that antibodies against interleukin-1β may decrease recurrent cardiovascular events in secondary prevention, various anti-inflammatory medications used for rheumatic conditions and new monoclonal antibody therapeutics have undergone rigorous evaluation. These data build towards a paradigm shift in secondary ASCVD prevention, underscoring the value of targeting multiple biological pathways in the management of both lipid levels and systemic inflammation. Evolving knowledge of the immune system, and the gut microbiota may result in opportunities for modifying previously unrecognized sources of residual inflammatory risk. This review provides an overview of novel therapeutic targets for ASCVD and emerging treatments with a focus on mechanisms, efficacy, and safety.

Gut-immune axis and cardiovascular risk in chronic kidney disease

Patients with chronic kidney disease (CKD) suffer from marked cardiovascular morbidity and mortality, so lowering the cardiovascular risk is paramount to improve quality of life and survival in CKD. Manifold mechanisms are hold accountable for the development of cardiovascular disease (CVD), and recently inflammation arose as novel risk factor significantly contributing to progression of CVD. While the gut microbiome was identified as key regulator of immunity and inflammation in several disease, CKD-related microbiome-immune interaction gains increasing importance. Here, we summarize the latest knowledge on microbiome dysbiosis in CKD, subsequent changes in bacterial and host metabolism and how this drives inflammation and CVD in CKD. Moreover, we outline potential therapeutic targets along the gut-immune-cardiovascular axis that could aid the combat of CVD development and high mortality in CKD.

Translational opportunities of single-cell biology in atherosclerosis

The advent of single-cell biology opens a new chapter for understanding human biological processes and for diagnosing, monitoring, and treating disease. This revolution now reaches the field of cardiovascular disease (CVD). New technologies to interrogate CVD samples at single-cell resolution are allowing the identification of novel cell communities that are important in shaping disease development and direct towards new therapeutic strategies. These approaches have begun to revolutionize atherosclerosis pathology and redraw our understanding of disease development. This review discusses the state-of-the-art of single-cell analysis of atherosclerotic plaques, with a particular focus on human lesions, and presents the current resolution of cellular subpopulations and their heterogeneity and plasticity in relation to clinically relevant features. Opportunities and pitfalls of current technologies as well as the clinical impact of single-cell technologies in CVD patient care are highlighted, advocating for multidisciplinary and international collaborative efforts to join the cellular dots of CVD.

Single-cell RNA sequencing to identify cellular heterogeneity and targets in cardiovascular diseases: from bench to bedside

The mechanisms of cardiovascular diseases (CVDs) remain incompletely elucidated. Single-cell RNA sequencing (scRNA-seq) has enabled the profiling of single-cell transcriptomes at unprecedented resolution and throughput, which is critical for deciphering cardiovascular cellular heterogeneity and underlying disease mechanisms, thereby facilitating the development of therapeutic strategies. In this review, we summarize cellular heterogeneity in cardiovascular homeostasis and diseases as well as the discovery of potential disease targets based on scRNA-seq, and yield new insights into the promise of scRNA-seq technology in precision medicine and clinical application.

Anti-Inflammatory Drug Candidates for Prevention and Treatment of Cardiovascular Diseases

Incidence and mortality rates for cardiovascular disease are declining, but it still remains a major cause of morbidity and mortality. Drug treatments to slow the progression of atherosclerosis focus on reducing cholesterol levels. The paradigm shift to consider atherosclerosis an inflammatory disease by itself has led to the development of new treatments. In this article, we discuss the pathophysiology of inflammation and focus attention on therapeutics targeting different inflammatory pathways of atherosclerosis and myocardial infarction. In atherosclerosis, colchicine is included in new recommendations, and eight randomized clinical trials are testing new drugs in different inflammatory pathways. After a myocardial infarction, no drug has shown a significant benefit, but we present four randomized clinical trials with new treatments targeting inflammation.

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 (TBRmax) 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.

Myocardial-Treg Crosstalk: How to Tame a Wolf

The immune system plays a vital role in maintaining tissue integrity and organismal homeostasis. The sudden stress caused by myocardial infarction (MI) poses a significant challenge for the immune system: it must quickly substitute dead myocardial with fibrotic tissue while controlling overt inflammatory responses. In this review, we will discuss the central role of myocardial regulatory T-cells (Tregs) in orchestrating tissue repair processes and controlling local inflammation in the context of MI. We herein compile recent advances enabled by the use of transgenic mouse models with defined cardiac antigen specificity, explore whole-heart imaging techniques, outline clinical studies and summarize deep-phenotyping conducted by independent labs using single-cell transcriptomics and T-cell repertoire analysis. Furthermore, we point to multiple mechanisms and cell types targeted by Tregs in the infarcted heart, ranging from pro-fibrotic responses in mesenchymal cells to local immune modulation in myeloid and lymphoid lineages. We also discuss how both cardiac-specific and polyclonal Tregs participate in MI repair. In addition, we consider intriguing novel evidence on how the myocardial milieu takes control of potentially auto-aggressive local immune reactions by shaping myosin-specific T-cell development towards a regulatory phenotype. Finally, we examine the potential use of Treg manipulating drugs in the clinic after MI.