A Unique Population of Regulatory T Cells in Heart Potentiates Cardiac Protection From Myocardial Infarction

Macrophage-produced VEGFC is induced by efferocytosis to ameliorate cardiac injury and inflammation

Clearance of dying cells by efferocytosis is necessary for cardiac repair after myocardial infarction (MI). Recent reports have suggested a protective role for vascular endothelial growth factor C (VEGFC) during acute cardiac lymphangiogenesis after MI. Here, we report that defective efferocytosis by macrophages after experimental MI led to a reduction in cardiac lymphangiogenesis and Vegfc expression. Cell-intrinsic evidence for efferocytic induction of Vegfc was revealed after adding apoptotic cells to cultured primary macrophages, which subsequently triggered Vegfc transcription and VEGFC secretion. Similarly, cardiac macrophages elevated Vegfc expression levels after MI, and mice deficient for myeloid Vegfc exhibited impaired ventricular contractility, adverse tissue remodeling, and reduced lymphangiogenesis. These results were observed in mouse models of permanent coronary occlusion and clinically relevant ischemia and reperfusion. Interestingly, myeloid Vegfc deficiency also led to increases in acute infarct size, prior to the amplitude of the acute cardiac lymphangiogenesis response. RNA-Seq and cardiac flow cytometry revealed that myeloid Vegfc deficiency was also characterized by a defective inflammatory response, and macrophage-produced VEGFC was directly effective at suppressing proinflammatory macrophage activation. Taken together, our findings indicate that cardiac macrophages promote healing through the promotion of myocardial lymphangiogenesis and the suppression of inflammatory cytokines.

Macrophage efferocytosis with VEGFC and lymphangiogenesis: rescuing the broken heart

Cardiac repair following ischemic injury is indispensable for survival and requires a coordinated cellular response involving the mobilization of immune cells from the secondary lymphoid organs to the site of damage. Efferocytosis, the engulfment of cell debris and dying cells by innate immune cells, along with lymphangiogenesis, the formation of new lymphatic vessels, are emerging as central to the cardiac healing response. In this issue of the JCI, Glinton et al. used state-of-the-art approaches to demonstrate that efferocytosis induced vascular endothelial growth factor C (VEGFC) in myeloid cells and stimulated lymphangiogenesis and cardiac repair. These findings provide impactful mechanistic information that can be leveraged to therapeutically target pathways in cardiac repair and ischemic heart failure.

The why and how of adaptive immune responses in ischemic cardiovascular disease

Atherosclerotic cardiovascular disease is a major cause of disability and death worldwide. Most therapeutic approaches target traditional risk factors but ignore the fundamental role of the immune system. This is a huge unmet need. Recent evidence indicates that reducing inflammation may limit cardiovascular events. However, the concomitant increase in the risk of lifethreatening infections is a major drawback. In this context, targeting adaptive immunity could constitute a highly effective and safer approach. In this Review, we address the why and how of the immuno-cardiovascular unit, in health and in atherosclerotic disease. We review and discuss fundamental mechanisms that ensure immune tolerance to cardiovascular tissue, and examine how their disruption promotes disease progression. We identify promising strategies to manipulate the adaptive immune system for patient benefit, including novel biologics and RNA-based vaccination strategies. Finally, we advocate for establishing a molecular classification of atherosclerosis as an important milestone in our quest to radically change the understanding and treatment of atherosclerotic disease.

Bile acid coordinates microbiota homeostasis and systemic immunometabolism in cardiometabolic diseases

Cardiometabolic disease (CMD), characterized with metabolic disorder triggered cardiovascular events, is a leading cause of death and disability. Metabolic disorders trigger chronic low-grade inflammation, and actually, a new concept of metaflammation has been proposed to define the state of metabolism connected with immunological adaptations. Amongst the continuously increased list of systemic metabolites in regulation of immune system, bile acids (BAs) represent a distinct class of metabolites implicated in the whole process of CMD development because of its multifaceted roles in shaping systemic immunometabolism. BAs can directly modulate the immune system by either boosting or inhibiting inflammatory responses via diverse mechanisms. Moreover, BAs are key determinants in maintaining the dynamic communication between the host and microbiota. Importantly, BAs via targeting Farnesoid X receptor (FXR) and diverse other nuclear receptors play key roles in regulating metabolic homeostasis of lipids, glucose, and amino acids. Moreover, BAs axis per se is susceptible to inflammatory and metabolic intervention, and thereby BAs axis may constitute a reciprocal regulatory loop in metaflammation. We thus propose that BAs axis represents a core coordinator in integrating systemic immunometabolism implicated in the process of CMD. We provide an updated summary and an intensive discussion about how BAs shape both the innate and adaptive immune system, and how BAs axis function as a core coordinator in integrating metabolic disorder to chronic inflammation in conditions of CMD.

Allergic asthma is a risk factor for human cardiovascular diseases

Asthma is an allergic airway disease in which type 2-mediated inflammation has a pathogenic role. Cardiovascular diseases (CVDs) are type 1-dominant inflammatory diseases in which type 2 cytokines often have a protective role. However, clinical studies demonstrate that allergic asthma and associated allergies are essential risk factors for CVD, including coronary heart diseases, aortic diseases, peripheral arterial diseases, pulmonary embolism, right ventricular dysfunction, atrial fibrillation, cardiac hypertrophy and even hypertension. Mast cells, eosinophils, inflammatory cytokines and immunoglobulin (Ig)E accumulate in asthmatic lungs and in the injured heart and vasculature of patients with CVD. Clinical studies show that many anti-asthmatic therapies affect the risk of CVD. As such, allergic asthma and CVD may share common pathogenic mechanisms. Preclinical investigations indicate that anti-asthmatic drugs have therapeutic potential in certain CVDs. In this Review, we discuss how asthma and allied allergic conditions may contribute to the prevalence, incidence and progression of CVD and vice versa.

Cellular Heterogeneity of the Heart

Recent advances in technology such as the introduction of high throughput multidimensional tools like single cell sequencing help to characterize the cellular composition of the human heart. The diversity of cell types that has been uncovered by such approaches is by far greater than ever expected before. Accurate identification of the cellular variety and dynamics will not only facilitate a much deeper understanding of cardiac physiology but also provide important insights into mechanisms underlying its pathological transformation. Distinct cellular patterns of cardiac cell clusters may allow differentiation between a healthy heart and a sick heart while potentially predicting future disease at much earlier stages than currently possible. These advances have already extensively improved and will ultimately revolutionize our knowledge of the mechanisms underlying cardiovascular disease as such. In this review, we will provide an overview of the cells present in the human and rodent heart as well as genes that may be used for their identification.

Immune cells in cardiac repair and regeneration

The immune system is fundamental to tissue homeostasis and is the first line of defense following infection, injury or disease. In the damaged heart, large numbers of immune cells are recruited to the site of injury. These cells play an integral part in both repair by scar formation and the initiation of tissue regeneration. They initially assume inflammatory phenotypes, releasing pro-inflammatory cytokines and removing dead and dying tissue, before entering a reparative stage, replacing dead muscle tissue with a non-contractile scar. In this Review, we present an overview of the innate and adaptive immune response to heart injury. We explore the kinetics of immune cell mobilization following cardiac injury and how the different innate and adaptive immune cells interact with one another and with the damaged tissue. We draw on key findings from regenerative models, providing insight into how to support a robust immune response permissible for cardiac regeneration. Finally, we consider how the latest technological developments can offer opportunities for a deeper and unbiased functional understanding of the immune response to heart disease, highlighting the importance of such knowledge as the basis for promoting regeneration following cardiac injury in human patients.

The therapeutic potential of regulatory T cells in reducing cardiovascular complications in patients with severe COVID-19

The SARS coronavirus 2 (SARS CoV-2) causes Coronavirus Disease (COVID-19), is an emerging viral infection. SARS CoV-2 infects target cells by attaching to Angiotensin-Converting Enzyme (ACE2). SARS CoV-2 could cause cardiac damage in patients with severe COVID-19, as ACE2 is expressed in cardiac cells, including cardiomyocytes, pericytes, and fibroblasts, and coronavirus could directly infect these cells. Cardiovascular disorders are the most frequent comorbidity found in COVID-19 patients. Immune cells such as monocytes, macrophages, and T cells may produce inflammatory cytokines and chemokines that contribute to COVID-19 pathogenesis if their functions are uncontrolled. This causes a cytokine storm in COVID-19 patients, which has been associated with cardiac damage. Tregs are a subset of immune cells that regulate immune and inflammatory responses. Tregs suppress inflammation and improve cardiovascular function through a variety of mechanisms. This is an exciting research area to explore the cellular, molecular, and immunological mechanisms related to reducing risks of cardiovascular complications in severe COVID-19. This review evaluated whether Tregs can affect COVID-19-related cardiovascular complications, as well as the mechanisms through which Tregs act.

Aorta Regulatory T Cells with a Tissue-Specific Phenotype and Function Promote Tissue Repair through Tff1 in Abdominal Aortic Aneurysms

In addition to maintaining immune tolerance, Foxp3⁺ regulatory T cells (Tregs) perform specialized functions in tissue homeostasis and remodeling. However, whether Tregs in aortic aneurysms have a tissue-specific phenotype and function is unclear. Here, a special group of Tregs that potentially inhibit abdominal aortic aneurysm (AAA) progression are identified and functionally characterized. Aortic Tregs gradually increase during the process of AAA and are mainly recruited from peripheral circulation. Single-cell TCR sequencing and bulk RNA sequencing demonstrate their unique phenotype and highly expressed trefoil factor 1 (Tff1). Foxp3^cre/cre Tff1^flox/flox mice are used to clarify the role of Tff1 in AAA, suggesting that aortic Tregs secrete Tff1 to regulate smooth muscle cell (SMC) survival. In vitro experiments confirm that Tff1 inhibits SMC apoptosis through the extracellular signal-regulated kinase (ERK) 1/2 pathway. The findings reveal a tissue-specific phenotype and function of aortic Tregs and may provide a promising and novel approach for the prevention of AAA.

Progress of Single-Cell RNA Sequencing Technology in Myocardial Infarction Research

After myocardial infarction, the heart enters a remodeling and repair phase that involves myocardial cell damage, inflammatory response, fibroblast activation, and, ultimately, angiogenesis. In this process, the proportions and functions of cardiomyocytes, immune cells, fibroblasts, endothelial cells, and other cells change. Identification of the potential differences in gene expression among cell types and/or transcriptome heterogeneity among cells of the same type greatly contribute to understanding the cellular changes that occur in heart and disease conditions. Recent advent of the single-cell transcriptome sequencing technology has facilitated the exploration of single cell diversity as well as comprehensive elucidation of the natural history and molecular mechanisms of myocardial infarction. In this manner, novel putative therapeutic targets for myocardial infarction treatment may be detected and clinically applied.

Cellular Phenotypic Transformation in Heart Failure Caused by Coronary Heart Disease and Dilated Cardiomyopathy: Delineating at Single-Cell Level

Heart failure (HF) is known as the final manifestation of cardiovascular diseases. Although cellular heterogeneity of the heart is well understood, the phenotypic transformation of cardiac cells in progress of HF remains obscure. This study aimed to analyze phenotypic transformation of cardiac cells in HF through human single-cell RNA transcriptome profile. Here, phenotypic transformation of cardiomyocytes (CMs), endothelial cells (ECs), and fibroblasts was identified by data analysis and animal experiments. Abnormal myosin subunits including the decrease in Myosin Heavy Chain 6, Myosin Light Chain 7 and the increase in Myosin Heavy Chain 7 were found in CMs. Two disease phenotypes of ECs named inflammatory ECs and muscularized ECs were identified. In addition, myofibroblast was increased in HF and highly associated with abnormal extracellular matrix. Our study proposed an integrated map of phenotypic transformation of cardiac cells and highlighted the intercellular communication in HF. This detailed definition of cellular transformation will facilitate cell-based mapping of novel interventional targets for the treatment of HF.

The Role of Matrix Proteins in Cardiac Pathology

The extracellular matrix (ECM) and ECM-regulatory proteins mediate structural and cell-cell interactions that are crucial for embryonic cardiac development and postnatal homeostasis, as well as organ remodeling and repair in response to injury. These proteins possess a broad functionality that is regulated by multiple structural domains and dependent on their ability to interact with extracellular substrates and/or cell surface receptors. Several different cell types (cardiomyocytes, fibroblasts, endothelial and inflammatory cells) within the myocardium elaborate ECM proteins, and their role in cardiovascular (patho)physiology has been increasingly recognized. This has stimulated robust research dissecting the ECM protein function in human health and disease and replicating the genetic proof-of-principle. This review summarizes recent developments regarding the contribution of ECM to cardiovascular disease. The clear importance of this heterogeneous group of proteins in attenuating maladaptive repair responses provides an impetus for further investigation into these proteins as potential pharmacological targets in cardiac diseases and beyond.

Human regulatory T cells locally differentiate and are functionally heterogeneous within the inflamed arthritic joint

Objective

Tregs are crucial for immune regulation, and environment‐driven adaptation of effector (e)Tregs is essential for local functioning. However, the extent of human Treg heterogeneity in inflammatory settings is unclear.

Methods

We combined single‐cell RNA‐ and TCR‐sequencing on Tregs derived from three to six patients with juvenile idiopathic arthritis (JIA) to investigate the functional heterogeneity of human synovial fluid (SF)‐derived Tregs from inflamed joints. Confirmation and suppressive function of the identified Treg clusters was assessed by flow cytometry.

Results

Four Treg clusters were identified; incoming, activated eTregs with either a dominant suppressive or cytotoxic profile, and GPR56⁺CD161⁺CXCL13⁺ Tregs. Pseudotime analysis showed differentiation towards either classical eTreg profiles or GPR56⁺CD161⁺CXCL13⁺ Tregs supported by TCR data. Despite its most differentiated phenotype, GPR56⁺CD161⁺CXCL13⁺ Tregs were shown to be suppressive. Furthermore, BATF was identified as an overarching eTreg regulator, with the novel Treg‐associated regulon BHLHE40 driving differentiation towards GPR56⁺CD161⁺CXCL13⁺ Tregs, and JAZF1 towards classical eTregs.

Conclusion

Our study reveals a heterogeneous population of Tregs at the site of inflammation in JIA. SF Treg differentiate to a classical eTreg profile with a more dominant suppressive or cytotoxic profile that share a similar TCR repertoire, or towards GPR56⁺CD161⁺CXCL13⁺ Tregs with a more distinct TCR repertoire. Genes characterising GPR56⁺CD161⁺CXCL13⁺ Tregs were also mirrored in other T‐cell subsets in both the tumor and the autoimmune setting. Finally, the identified key regulators driving SF Treg adaptation may be interesting targets for autoimmunity or tumor interventions.

Organized Chaos: Deciphering Immune Cell Heterogeneity's Role in Inflammation in the Heart

During homeostasis, immune cells perform daily housekeeping functions to maintain heart health by acting as sentinels for tissue damage and foreign particles. Resident immune cells compose 5% of the cellular population in healthy human ventricular tissue. In response to injury, there is an increase in inflammation within the heart due to the influx of immune cells. Some of the most common immune cells recruited to the heart are macrophages, dendritic cells, neutrophils, and T-cells. In this review, we will discuss what is known about cardiac immune cell heterogeneity during homeostasis, how these cell populations change in response to a pathology such as myocardial infarction or pressure overload, and what stimuli are regulating these processes. In addition, we will summarize technologies used to evaluate cell heterogeneity in models of cardiovascular disease.

Recent Progress in Cardiovascular Research Involving Single-Cell Omics Approaches

Cardiovascular diseases are among the leading causes of morbidity and mortality worldwide. Although the spectrum of the heart from development to disease has long been studied, it remains largely enigmatic. The emergence of single-cell omics technologies has provided a powerful toolbox for defining cell heterogeneity, unraveling previously unknown pathways, and revealing intercellular communications, thereby boosting biomedical research and obtaining numerous novel findings over the last 7 years. Not only cell atlases of normal and developing hearts that provided substantial research resources, but also some important findings regarding cell-type-specific disease gene program, could never have been established without single-cell omics technologies. Herein, we briefly describe the latest technological advances in single-cell omics and summarize the major findings achieved by such approaches, with a focus on development and homeostasis of the heart, myocardial infarction, and heart failure.

Failing Heart Transplants and Rejection-A Cellular Perspective

The median survival of patients with heart transplants is relatively limited, implying one of the most relevant questions in the field—how to expand the lifespan of a heart allograft? Despite optimal transplantation conditions, we do not anticipate a rise in long-term patient survival in near future. In order to develop novel strategies for patient monitoring and specific therapies, it is critical to understand the underlying pathological mechanisms at cellular and molecular levels. These events are driven by innate immune response and allorecognition driven inflammation, which controls both tissue damage and repair in a spatiotemporal context. In addition to immune cells, also structural cells of the heart participate in this process. Novel single cell methods have opened new avenues for understanding the dynamics driving the events leading to allograft failure. Here, we review current knowledge on the cellular composition of a normal heart, and cellular mechanisms of ischemia-reperfusion injury (IRI), acute rejection and cardiac allograft vasculopathy (CAV) in the transplanted hearts. We highlight gaps in current knowledge and suggest future directions, in order to improve cellular and molecular understanding of failing heart allografts.

Toward a Paradigm to Distinguish Distinct Functions of FOXP3+ Regulatory T Cells

FOXP3⁺ regulatory T (Treg) cells are a unique subset of CD4⁺ T cells that classically function as master regulators of immune homeostasis. Besides this canonical suppressive role, which is required to maintain self-tolerance, a growing body of literature has identified Treg cells as critical orchestrators of tissue protection during acute stress and as effector cells that drive repair following tissue injury. Despite substantial interest in these distinct roles, the field has struggled to disentangle Treg cell suppressive functions from those that promote tissue defense and repair. In this article, we will examine the literature in the context of specific physiologic settings, contrasting the suppressive function of Treg cells with their emerging roles in promoting tissue homeostasis and tissue repair. Further, we will discuss a new paradigm differentiating tissue defense from tissue repair-a paradigm needed to translate Treg cell-based therapies to the clinic.

Coronary vasodilation mediated by T cells expressing choline acetyltransferase

CD4⁺ T cells expressing choline acetyltransferase (ChAT) have recently been shown to cause a drop in systemic blood pressure when infused into mice. The aim of this study was to determine if ChAT-expressing T cells could regulate coronary vascular reactivity. Preconstricted segments of epicardial and intramyocardial porcine coronary arteries relaxed in response to Jurkat T cells (JT) that overexpressed ChAT (JT_ChAT cells). The efficacy of the JT_ChAT cells was similar in epicardial and intramyocardial vessels with a maximum dilator response to 3 × 10⁵ cells/mL of 38.0 ± 6.7% and 38.7 ± 7.25%, respectively. In contrast, nontransfected JT cells elicited a weak dilator response, followed by a weak contraction. The response of JT_ChAT cells was dependent on the presence of the endothelial cells. In addition, the response could be significantly reduced by N^ω-nitro-l-arginine methyl ester (l-NAME) and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) in the presence of indomethacin. JT_ChAT cells, but not JT cells, increased the expression of phosphorylated endothelial nitric oxide synthase (eNOS). JT_ChAT cells contained significantly greater levels of acetylcholine compared with JT cells; however, the nonselective muscarinic antagonist atropine and the M₁ receptor antagonist pirenzepine both failed to block the dilator effect of JT_ChAT cells. Exogenously added acetylcholine induced only a weak relaxation (∼10%) at low concentrations, which became a contractile response at higher concentrations. These data illustrate the capacity for cells that express ChAT to regulate coronary vascular reactivity, via mechanisms that are dependent on interaction with the endothelium and in part mediated by the release of nitric oxide.NEW & NOTEWORTHY This study shows ChAT-expressing T cells can induce vasodilation of the blood vessel in the coronary circulation and that this effect relies on a direct interaction between T cells and the coronary vascular endothelium. The study establishes a potential immunomodulatory role for T cells in the coronary circulation. The present findings offer an additional possibility that a deficiency of ChAT-expressing T cells could contribute to reduced coronary blood flow and ischemic events in the myocardium.

Regulatory T Cells in Chronic Heart Failure

Heart failure is a global problem with high hospitalization and mortality rates. Inflammation and immune dysfunction are involved in this disease. Owing to their unique function, regulatory T cells (Tregs) have reacquired attention recently. They participate in immunoregulation and tissue repair in the pathophysiology of heart failure. Tregs are beneficial in heart by suppressing excessive inflammatory responses and promoting stable scar formation in the early stage of heart injury. However, in chronic heart failure, the phenotypes and functions of Tregs changed. They transformed into an antiangiogenic and profibrotic cell type. In this review, we summarized the functions of Tregs in the development of chronic heart failure first. Then, we focused on the interactions between Tregs and their target cells. The target cells of Tregs include immune cells (such as monocytes/macrophages, dendritic cells, T cells, and B cells) and parenchymal cells (such as cardiomyocytes, fibroblasts, and endothelial cells). Next-generation sequencing and gene editing technology make immunotherapy of heart failure possible. So, prospective therapeutic approaches based on Tregs in chronic heart failure had also been evaluated.

Lymphatic Clearance of Immune Cells in Cardiovascular Disease

Recent advances in our understanding of the lymphatic system, its function, development, and role in pathophysiology have changed our views on its importance. Historically thought to be solely involved in the transport of tissue fluid, lipids, and immune cells, the lymphatic system displays great heterogeneity and plasticity and is actively involved in immune cell regulation. Interference in any of these processes can be deleterious, both at the developmental and adult level. Preclinical studies into the cardiac lymphatic system have shown that invoking lymphangiogenesis and enhancing immune cell trafficking in ischaemic hearts can reduce myocardial oedema, reduce inflammation, and improve cardiac outcome. Understanding how immune cells and the lymphatic endothelium interact is also vital to understanding how the lymphatic vascular network can be manipulated to improve immune cell clearance. In this Review, we examine the different types of immune cells involved in fibrotic repair following myocardial infarction. We also discuss the development and function of the cardiac lymphatic vasculature and how some immune cells interact with the lymphatic endothelium in the heart. Finally, we establish how promoting lymphangiogenesis is now a prime therapeutic target for reducing immune cell persistence, inflammation, and oedema to restore heart function in ischaemic heart disease.

IL-33 activates mTORC1 and modulates glycolytic metabolism in CD8+ T cells

Interleukin (IL)-33, a member in the IL-1 family, plays a central role in innate and adaptive immunity; however, how IL-33 mediates cytotoxic T-cell regulation and the downstream signals remain elusive. In this study, we found increased mouse IL-33 expression in CD8⁺ T cells following cell activation via anti-CD3/CD28 stimulation in vitro or lymphocytic choriomeningitis virus (LCMV) infection in vivo. Our cell adoptive transfer experiment demonstrated that extracellular, but not nuclear, IL-33 contributed to the activation and proliferation of CD8⁺ , but not CD4⁺ T effector cells in LCMV infection. Importantly, IL-33 induced mTORC1 activation in CD8⁺ T cells as evidenced by increased phosphorylated S6 ribosomal protein (p-S6) levels both in vitro and in vivo. Meanwhile, this IL-33-induced CD8⁺ T-cell activation was suppressed by mTORC1 inhibitors. Furthermore, IL-33 elevated glucose uptake and lactate production in CD8⁺ T cells in both dose- and time-dependent manners. The results of glycolytic rate assay demonstrated the increased glycolytic capacity of IL-33-treated CD8⁺ T cells compared with that of control cells. Our mechanistic study further revealed the capacity of IL-33 in promoting the expression of glucose transporter 1 (Glut1) and glycolytic enzymes via mTORC1, leading to accelerated aerobic glucose metabolism Warburg effect and increased effector T-cell activation. Together, our data provide new insights into IL-33-mediated regulation of CD8⁺ T cells, which might be beneficial for therapeutic strategies of inflammatory and infectious diseases in the future.

The role of T cells in age-related diseases

Age-related T cell dysfunction can lead to failure of immune tolerance mechanisms, resulting in aberrant T cell-driven cytokine and cytotoxic responses that ultimately cause tissue damage. In this Review, we discuss the role of T cells in the onset and progression of age-associated conditions, focusing on cardiovascular disorders, metabolic dysfunction, neuroinflammation and defective tissue repair and regeneration. We present different mechanisms by which T cells contribute to inflammageing and might act as modulators of age-associated diseases, including through enhanced pro-inflammatory and cytotoxic activity, defective clearance of senescent cells or regulation of the gut microbiota. Finally, we propose that 'resetting' immune system tolerance or targeting pathogenic T cells could open up new therapeutic opportunities to boost resilience to age-related diseases.

Ex uno, plures-From One Tissue to Many Cells: A Review of Single-Cell Transcriptomics in Cardiovascular Biology

Recent technological advances have revolutionized the study of tissue biology and garnered a greater appreciation for tissue complexity. In order to understand cardiac development, heart tissue homeostasis, and the effects of stress and injury on the cardiovascular system, it is essential to characterize the heart at high cellular resolution. Single-cell profiling provides a more precise definition of tissue composition, cell differentiation trajectories, and intercellular communication, compared to classical bulk approaches. Here, we aim to review how recent single-cell multi-omic studies have changed our understanding of cell dynamics during cardiac development, and in the healthy and diseased adult myocardium.

A narrative review of the potential pharmacological influence and safety of ibuprofen on coronavirus disease 19 (COVID-19), ACE2, and the immune system: a dichotomy of expectation and reality

The coronavirus disease 19 (COVID-19) pandemic is currently the most acute healthcare challenge in the world. Despite growing knowledge of the nature of Severe Acute Respiratory Syndrome coronavirus-2 (SARS-CoV-2), treatment options are still poorly defined. The safety of non-steroidal anti-inflammatory drugs (NSAIDs), specifically ibuprofen, has been openly questioned without any supporting evidence or clarity over dose, duration, or temporality of administration. This has been further conflicted by the initiation of studies to assess the efficacy of ibuprofen in improving outcomes in severe COVID-19 patients. To clarify the scientific reality, a literature search was conducted alongside considerations of the pharmacological properties of ibuprofen in order to construct this narrative review. The literature suggests that double-blind, placebo-controlled study results must be reported and carefully analysed for safety and efficacy in patients with COVID-19 before any recommendations can be made regarding the use of ibuprofen in such patients. Limited studies have suggested: (i) no direct interactions between ibuprofen and SARS-CoV-2 and (ii) there is no evidence to suggest ibuprofen affects the regulation of angiotensin-converting-enzyme 2 (ACE2), the receptor for COVID-19, in human studies. Furthermore, in vitro studies suggest ibuprofen may facilitate cleavage of ACE2 from the membrane, preventing membrane-dependent viral entry into the cell, the clinical significance of which is uncertain. Additionally, in vitro evidence suggests that inhibition of the transcription factor nuclear factor-κB (NF-kB) by ibuprofen may have a role in reducing excess inflammation or cytokine release in COVID-19 patients. Finally, there is no evidence that ibuprofen will aggravate or increase the chance of infection of COVID-19.