Prior β-blocker treatment decreases leukocyte responsiveness to injury

Neuroimmune Interactions and Their Role in Immune Cell Trafficking in Cardiovascular Diseases and Cancer

Sympathetic nerves innervate bone marrow and various immune organs, where norepinephrine-the primary sympathetic neurotransmitter-directly interacts with immune cells that express adrenergic receptors. This article reviewed the key molecular pathways triggered by sympathetic activation and explored how sympathetic activity influences immune cell migration. Norepinephrine serves as a chemoattractant for monocytes, macrophages, and stem cells, promoting the migration of myeloid cells while inhibiting the migration of lymphocytes at physiological concentrations. We also examined the role of immune cell infiltration in cardiovascular diseases and cancer. Evidence suggests that sympathetic activation increases myeloid cell infiltration into target tissues across various cardiovascular diseases, including atherosclerosis, hypertension, cardiac fibrosis, cardiac hypertrophy, arrhythmia, myocardial infarction, heart failure, and stroke. Conversely, inhibiting sympathetic activity may serve as a potential therapeutic strategy to treat these conditions by reducing macrophage infiltration. Furthermore, sympathetic activation promotes macrophage accumulation in cancer tissues, mirroring its effects in cardiovascular diseases, while suppressing T lymphocyte infiltration into cancerous sites. These changes contribute to increased cancer growth and metastasis. Thus, inhibiting sympathetic activation could help to protect against cancer by enhancing T cell infiltration and reducing macrophage presence in tumors.

The spleen in ischaemic heart disease

Ischaemic heart disease is a consequence of coronary atherosclerosis, and atherosclerosis is a systemic inflammatory disease. The spleen releases various immune cells in temporally distinct patterns. Neutrophils, monocytes, macrophages, B cells and T cells execute innate and adaptive immune processes in the coronary atherosclerotic plaque and in the ischaemic myocardium. Prolonged inflammation contributes to ischaemic heart failure. The spleen is also a target of neuromodulation through vagal, sympathetic and sensory nerve activation. Efferent vagal activation and subsequent activation of the noradrenergic splenic nerve activate β2-adrenergic receptors on splenic T cells, which release acetylcholine that ultimately results in attenuation of cytokine secretion from splenic macrophages. Coeliac vagal nerve activation increases splenic sympathetic nerve activity and drives the release of T cells, a process that depends on placental growth factor. Activation of the vagosplenic axis protects acutely from ischaemia-reperfusion injury during auricular tragus vagal stimulation and remote ischaemic conditioning. Splenectomy abrogates all these deleterious and beneficial actions on the cardiovascular system. The aggregate effect of splenectomy in humans is a long-term increase in mortality from ischaemic heart disease. The spleen has been appreciated as an important immune organ for inflammatory processes in atherosclerosis, myocardial infarction and heart failure, whereas its complex interaction with circulating blood factors and with the autonomic and somatic nervous systems, as well as its role in cardioprotection, have emerged only in the past decade. In this Review, we describe this newly identified cardioprotective function of the spleen and highlight the potential for translating the findings to patients with ischaemic heart disease.

Germline deletion of Rgs2 and/or Rgs5 in male mice does not exacerbate left ventricular remodeling induced by subchronic isoproterenol infusion

Sympathoexcitation is a hallmark of heart failure, with sustained β-adrenergic receptor (βAR)-G protein signaling activation. βAR signaling is modulated by regulator of G protein signaling (RGS) proteins. Previously, we reported that Gαi/o regulation by RGS2 or RGS5 is key to ventricular rhythm regulation, while the dual loss of both RGS proteins results in left ventricular (LV) dilatation and dysfunction. Here, we tested whether sustained βAR stimulation with isoproterenol (ISO, 30 mg/kg/day, 3 days) exacerbates LV remodeling in male mice with germline deletion of Rgs2 and/or Rgs5. Rgs2 KO and Rgs2/5 dbKO mice showed LV dilatation at baseline, which was unchanged by ISO. Rgs2 or Rgs5 deletion decreased Rgs1 expression, whereas Rgs5 deletion increased Rgs4 expression. ISO induced cardiac hypertrophy and interstitial fibrosis in Rgs2/5 dbKO mice without increasing cardiomyocyte size or LV dilation but increased expression of cardiac fetal gene Nppa, α-actinin, and Ca2+-/calmodulin-dependent kinase II. Single Rgs2 and Rgs5 KO mice had markedly increased CD45+ cells, whereas tissue from Rgs5 KO mice showed increased CD68+ cells, as revealed by immunohistochemistry. The results together indicate that ventricular remodeling due to Rgs2 and/or Rgs5 deletion is associated with augmented myocardial immune cell presence but is not exacerbated by sustained βAR stimulation.

Analysis of serum concentrations of metoprolol and its metabolite α-hydroxymetoprolol in patients with heart failure with reduced ejection fraction: a pilot study in routine health care

BACKGROUND

The cardioselective β-1 receptor antagonist metoprolol is used to treat heart failure. It is metabolized in the liver, primarily by cytochrome 2D6.

RESEARCH DESIGN AND METHODS

In this study, trough serum concentrations of metoprolol and its metabolite α-hydroxymetoprolol were measured in patients with heart failure with reduced ejection fraction.

RESULTS

Concentrations were 1.3-122.9 µg/L for metoprolol and 1.3-125.7 µg/L for α-hydroxymetoprolol, metabolic ratios were 0.11-98.32. The median weight-adjusted apparent clearance of metoprolol was 53.07 (range 3.24-500.0). Metoprolol and α-hydroxymetoprolol concentrations correlated with both daily dose and dose per kilogram of body weight. However, metoprolol concentrations at the same daily dose showed a wide variability. Patients taking 100 mg/day had significantly lower NT-proBNP values than those taking 25 or 50 mg/day. Patients with LVEF ≤ 35% versus > 35% used significantly lower daily doses and doses per kilogram of body weight, although metoprolol concentrations did not differ. A poor cytochrome 2D6 metabolizer phenotype was detected in two patients.

CONCLUSIONS

Metoprolol concentrations showed a wide interindividual variability at the same daily dose. Simultaneous determination of metoprolol and α-hydroxymetoprolol concentrations could identify patients at risk of possible accumulation of metoprolol leading to intoxication or, conversely, patients at risk of underdosing. [Figure: see text].

Adrenergic orchestration of immune cell dynamics in response to cardiac stress

Immune cells contribute approximately 5-10 % of the heart's total cell population, including several myeloid cell and lymphocyte cell subsets, which, despite their relatively small percentages, play important roles in cardiac homeostasis and remodeling responses to various forms of injury and long-term stress. Pathological cardiac stress activates the sympathetic nervous system (SNS), resulting in the release of the catecholamines epinephrine and norepinephrine either systemically or from sympathetic nerve terminals within various lymphoid organs. Acting at α- or β-adrenergic receptors (αAR, βAR), catecholamines regulate immune cell hematopoiesis, egress and migration in response to stress. Classically, αAR stimulation tends to promote inflammatory responses while βAR stimulation has typically been shown to be immunosuppressive, though the effects can be nuanced depending on the immune cells subtype, the site of regulation and pathophysiological context. Herein, we will discuss several facets of SNS-mediated regulation of immune cells and their response to cardiac stress, including: catecholamine response to cardiovascular stress and action at their receptors, adrenergic regulation of hematopoiesis, immune cell retention and release from the bone marrow, adrenergic regulation of splenic immune cells and their retention, as well as adrenergic regulation of immune cell recruitment to the injured heart, including neutrophils, monocytes and macrophages. A particular focus will be given to βAR-mediated effects on myeloid cells in response to acute or chronic cardiac stress.

Inhibition of differentiation of monocyte-derived macrophages toward an M2-Like phenotype May Be a neglected mechanism of β-AR receptor blocker therapy for atherosclerosis

The clinical efficacy of adrenergic β-receptor (β-AR) blockers in significantly stabilizing atherosclerotic plaques has been extensively supported by evidence-based medical research; however, the underlying mechanism remains unclear. Recent findings have highlighted the impact of lipid-induced aberrant polarization of macrophages during normal inflammatory-repair and regenerative processes on atherosclerosis formation and progression. In this review, we explore the relationship between macrophage polarization and atherosclerosis, as well as the influence of β-AR blockers on macrophage polarization. Based on the robust evidence supporting the use of β-AR blockers for treating atherosclerosis, we propose that their main mechanism involves inhibiting monocyte-derived macrophage differentiation towards an M2-like phenotype.

Propranolol Promotes Monocyte-to-Macrophage Differentiation and Enhances Macrophage Anti-Inflammatory and Antioxidant Activities by NRF2 Activation

Adrenergic pathways represent the main channel of communication between the nervous system and the immune system. During inflammation, blood monocytes migrate within tissue and differentiate into macrophages, which polarize to M1 or M2 macrophages with tissue-damaging or -reparative properties, respectively. This study investigates whether the β-adrenergic receptor (β-AR)-blocking drug propranolol modulates the monocyte-to-macrophage differentiation process and further influences macrophages in their polarization toward M1- and M2-like phenotypes. Six-day-human monocytes were cultured with M-CSF in the presence or absence of propranolol and then activated toward an M1 pro-inflammatory state or an M2 anti-inflammatory state. The chronic exposure of monocytes to propranolol during their differentiation into macrophages promoted the increase in the M1 marker CD16 and in the M2 markers CD206 and CD163 and peroxisome proliferator-activated receptor ɣ expression. It also increased endocytosis and the release of IL-10, whereas it reduced physiological reactive oxygen species. Exposure to the pro-inflammatory conditions of propranolol-differentiated macrophages resulted in an anti-inflammatory promoting effect. At the molecular level, propranolol upregulated the expression of the oxidative stress regulators NRF2, heme oxygenase-1 and NQO1. By contributing to regulating macrophage activities, propranolol may represent a novel anti-inflammatory and immunomodulating compound with relevant therapeutic potential in several inflammatory diseases.

Immunomodulation and immunopharmacology in heart failure

The immune system is intimately involved in the pathophysiology of heart failure. However, it is currently underused as a therapeutic target in the clinical setting. Moreover, the development of novel immunomodulatory therapies and their investigation for the treatment of patients with heart failure are hampered by the fact that currently used, evidence-based treatments for heart failure exert multiple immunomodulatory effects. In this Review, we discuss current knowledge on how evidence-based treatments for heart failure affect the immune system in addition to their primary mechanism of action, both to inform practising physicians about these pleiotropic actions and to create a framework for the development and application of future immunomodulatory therapies. We also delineate which subpopulations of patients with heart failure might benefit from immunomodulatory treatments. Furthermore, we summarize completed and ongoing clinical trials that assess immunomodulatory treatments in heart failure and present several therapeutic targets that could be investigated in the future. Lastly, we provide future directions to leverage the immunomodulatory potential of existing treatments and to foster the investigation of novel immunomodulatory therapeutics.

Co-release of cytokines after drug-eluting stent implantation in acute myocardial infarction patients with PCI

Acute Myocardial Infarction (AMI) after Percutaneous Coronary Intervention (PCI) often requires stent implantation leading to cardiovascular injury and cytokine release. Stent implantation induces cytokines production including TNFα, Hs-CRP, IL-1ß, IL2 receptor, IL6, IL8, and IL10, but their co-release is not extensively established. In 311 PCI patients with Drug-Eluting Stent (DES) implantation, we statistically evaluate the correlation of these cytokines release in various clinical conditions, stent numbers, and medications. We observed that TNFα is moderately correlated with IL-1ß (r2 = 0.59, p = 0.001) in diabetic PCI patients. Similarly, in NSTEMI (Non-ST Segment Elevation) patients, TNFα is strongly correlated with both IL-1ß (r2 = 0.97, p = 0.001) and IL8 (r2 = 0.82, p = 0.001). In CAD (Coronary Artery Disease)-diagnosed patients TNFα is highly correlated (r2 = 0.84, p = 0.0001) with IL8 release but not with IL-1ß. In patients with an increased number of stents, Hs-CRP is significantly coupled with IL8 > 5 pg/ml (t-statistic = 4.5, p < 0.0001). Inflammatory suppressor drugs are correlated as TNFα and IL8 are better suppressed by Metoprolol 23.75 (r2 = 0.58, p < 0.0001) than by Metoprolol 11.87 (r2 = 0.80, p = 0.5306). Increased TNFα and IL-1ß are better suppressed by the antiplatelet drug Brilinta (r2 = 0.30, p < 0.0001) but not with Clopidogrel (r2 = 0.87, p < 0.0001). ACI/ARB Valsartan 80 (r2 = 0.43, p = 0.0011) should be preferred over Benazepril 5.0 (r2 = 0.9291, p < 0.0001) or Olmesartan (r2 = 0.90, p = 0.0001). Thus, the co-release of IL-1ß, IL8 with TNFα, or only IL8 with TNFα could be a better predictor for the outcome of stent implantation in NSTEMI and CAD-diagnosed AMI patients respectively. Cytokine suppressive medications should be chosen carefully to inhibit further cardiovascular damage.

Local analgesia of electroacupuncture is mediated by the recruitment of neutrophils and released β-endorphins

ABSTRACT

The efficacy of acupuncture in treating pain diseases has been recognized in clinical practice, and its mechanism of action has been a hot topic in academic acupuncture research. Previous basic research on acupuncture analgesia has focused mostly on the nervous system, with few studies addressing the immune system as a potential pathway of acupuncture analgesia. In this study, we investigated the effect of electroacupuncture (EA) on the β-endorphins (β-END) content, END-containing leukocyte type and number, sympathetic neurotransmitter norepinephrine (NE), and chemokine gene expression in inflamed tissues. To induce inflammatory pain, about 200 µL of complete Frester adjuvant (CFA) was injected into the unilateral medial femoral muscle of adult Wistar rats. Electroacupuncture treatment was performed for 3 days beginning on day 4 after CFA injection, with parameters of 2/100 Hz, 2 mA, and 30 minutes per treatment. The weight-bearing experiment and enzyme-linked immunosorbent assay showed that EA treatment significantly relieved spontaneous pain-like behaviors and increased the level of β-END in inflamed tissue. Injection of anti-END antibody in inflamed tissue blocked this analgesic effect. Flow cytometry and immunofluorescence staining revealed that the EA-induced increase in β-END was derived from opioid-containing ICAM-1 + /CD11b + immune cells in inflamed tissue. In addition, EA treatment increased the NE content and expression of β2 adrenergic receptor (ADR-β2) in inflammatory tissues and upregulated Cxcl1 and Cxcl6 gene expression levels. These findings provide new evidence for the peripheral analgesic effect of acupuncture treatment by recruiting β-END-containing ICAM-1 + /CD11b + immune cells and increasing the β-END content at the site of inflammation.

Multi-omic analysis of the cardiac cellulome defines a vascular contribution to cardiac diastolic dysfunction in obese female mice

Coronary microvascular dysfunction (CMD) is associated with cardiac dysfunction and predictive of cardiac mortality in obesity, especially in females. Clinical data further support that CMD associates with development of heart failure with preserved ejection fraction and that mineralocorticoid receptor (MR) antagonism may be more efficacious in obese female, versus male, HFpEF patients. Accordingly, we examined the impact of smooth muscle cell (SMC)-specific MR deletion on obesity-associated coronary and cardiac diastolic dysfunction in female mice. Obesity was induced in female mice via western diet (WD) feeding alongside littermates fed standard diet. Global MR blockade with spironolactone prevented coronary and cardiac dysfunction in obese females and specific deletion of SMC-MR was sufficient to prevent obesity-associated coronary and cardiac diastolic dysfunction. Cardiac gene expression profiling suggested reduced cardiac inflammation in WD-fed mice with SMC-MR deletion independent of blood pressure, aortic stiffening, and cardiac hypertrophy. Further mechanistic studies utilizing single-cell RNA sequencing of non-cardiomyocyte cell populations revealed novel impacts of SMC-MR deletion on the cardiac cellulome in obese mice. Specifically, WD feeding induced inflammatory gene signatures in non-myocyte populations including B/T cells, macrophages, and endothelium as well as increased coronary VCAM-1 protein expression, independent of cardiac fibrosis, that was prevented by SMC-MR deletion. Further, SMC-MR deletion induced a basal reduction in cardiac mast cells and prevented WD-induced cardiac pro-inflammatory chemokine expression and leukocyte recruitment. These data reveal a central role for SMC-MR signaling in obesity-associated coronary and cardiac dysfunction, thus supporting the emerging paradigm of a vascular origin of cardiac dysfunction in obesity.

Quo Vadis? Immunodynamics of Myeloid Cells after Myocardial Infarction

Myocardial infarction (MI), a major contributor to worldwide morbidity and mortality, is caused by a lack of blood flow to the heart. Affected heart tissue becomes ischemic due to deficiency of blood perfusion and oxygen delivery. In case sufficient blood flow cannot be timely restored, cardiac injury with necrosis occurs. The ischemic/necrotic area induces a systemic inflammatory response and hundreds of thousands of leukocytes are recruited from the blood to the injured heart. The blood pool of leukocytes is rapidly depleted and urgent re-supply of these cells is needed. Myeloid cells are generated in the bone marrow (BM) and spleen, released into the blood, travel to sites of need, extravasate and accumulate inside tissues to accomplish various functions. In this review we focus on the "leukocyte supply chain" and will separately evaluate different myeloid cell compartments (BM, spleen, blood, heart) in steady state and after MI. Moreover, we highlight the local and systemic kinetics of extracellular factors, chemokines and danger signals involved in the regulation of production/generation, release, transportation, uptake, and activation of myeloid cells during the inflammatory phase of MI.

Pepducin-mediated G Protein-Coupled Receptor Signaling in the Cardiovascular System

ABSTRACT

Pepducins are small-lipidated peptides designed from the intracellular loops of G protein-coupled receptors (GPCRs) that act in an allosteric manner to modulate the activity of GPCRs. Over the past 2 decades, pepducins have progressed initially from pharmacologic tools used to manipulate GPCR activity in an orthosteric site-independent manner to compounds with therapeutic potential that have even been used safely in phase 1 and 2 clinical trials in human subjects. The effect of pepducins at their cognate receptors has been shown to vary between antagonist, partial agonist, and biased agonist outcomes in various primary and clonal cell systems, with even small changes in amino acid sequence altering these properties and their receptor selectivity. To date, pepducins designed from numerous GPCRs have been studied for their impact on pathologic conditions, including cardiovascular diseases such as thrombosis, myocardial infarction, and atherosclerosis. This review will focus in particular on pepducins designed from protease-activated receptors, C-X-C motif chemokine receptors, formyl peptide receptors, and the β2-adrenergic receptor. We will discuss the historic context of pepducin development for each receptor, as well as the structural, signaling, pathophysiologic consequences, and therapeutic potential for each pepducin class.

Beta-blockers for Atherosclerosis Prevention: a Missed Opportunity?

PURPOSE OF REVIEW

Current guidelines for the management of arterial hypertension endorse β-adrenergic receptor blocking agents (beta-blockers, BBs) as being particularly useful for hypertension in specific situations such as symptomatic angina, tachycardia, post-myocardial infarction, heart failure with reduced ejection fraction (HFrEF), and as an alternative to angiotensin-converting enzyme (ACE) inhibitors or angiotensin receptor blockers (ARBs) in hypertensive women planning pregnancy or at least of child-bearing potential. One of the most common uses of BBs is in patients with a recent myocardial infarction, with or without hypertension. Although this one use is specifically in a setting of atherosclerotic cardiovascular disease (ASCVD), it is not primarily for atheroprevention, but rather for cases with impaired systolic function, and it is intended primarily to lessen adverse cardiac remodeling and worsening of congestive heart failure (CHF). The BB class consists of numerous agents which differ widely in pharmacologic properties and physiologic effects. These differences include selectivity for β-adrenergic receptors and their subtypes, hydro- or lipophilicity, effects on blood pressure and heart rate, influence on lipoprotein and glucose metabolism, and direct impact on the artery wall, including platelet reactivity, endothelial function, infiltration of inflammatory cells and on inflammation per se, and on smooth muscle cell proliferation. Importantly, BBs are not commonly used for prevention of atherosclerosis or ASCVD per se. Many studies of early-generation BBs showed adverse effects on lipoprotein levels and metabolism of glucose and insulin and thus discouraged their use in atheroprevention. Nevertheless, newer BBs often have neutral or favorable metabolic effects on these important factors in ASCVD pathophysiology, and recent scientific studies now document direct beneficial effects of BBs on the artery wall. This document reviews both types of newer data, not only to encourage consideration of BB treatment to reduce ASCVD in the present, but also to call for future research to better explore the clinical settings in which BBs may be proven to have additional benefit in preventing ASCVD when added to the better-established treatments for dyslipidemia and diabetes.

RECENT FINDINGS

Relatively recent publications have clarified the diversity among BBs regarding adverse, neutral, or favorable effects on lipoproteins (especially triglycerides (TG) and low-density lipoprotein (LDL)) and on glucose/insulin metabolism. Specifically, the newer BBs (metoprolol ER, carvedilol ER, bisoprolol, and nebivolol) are now documented to be metabolically beneficial. These new data are complex but instructive regarding potential mechanisms of the diverse effects of various BBs on metabolism. Further and more importantly, these new data refute the traditional, but now outmoded, concept that BBs are universally harmful metabolically and therefore must be used sparingly, if at all, for atheroprevention. Recent studies have also reported exciting new data regarding how certain BBs can reduce platelet adhesion and improve the function of the major cell types in the artery wall, including the endothelium, macrophages, and smooth muscle cells. Specifically, BBs can improve endothelial function by enhancing arterial vasodilation and by reducing monocyte adhesion and transmigration. Further, BBs can decrease numbers and activity of inflammatory cells, including decreasing proliferation of smooth muscle cells and their transformation into inflammatory cells. These data help with the crucial step of distinguishing among available BBs regarding their likely overall arterial effects, whether to accelerate or prevent the development of atherosclerosis. In this regard, there is even some limited published information beyond these intermediary steps, going directly to the clinically more important endpoints of atherosclerosis and ASCVD events. The negative metabolic effects observed with the use of traditional/earlier generations of BBs have discouraged use of any BBs to prevent ASCVD. These adverse effects are not seen, however, with newer BBs. Thus, BBs continue to be a useful component of combination regimens not only in the treatment of arterial hypertension, heart failure, and arrhythmia, but also potentially in the prevention of atherosclerosis and ASCVD. Despite this exciting potential, further research is greatly needed to better establish the possible benefits of the most promising BBs as they might work in combination with other better-established atheropreventive agents. Specifically, there is a need for randomized, prospective, cardiovascular outcome trials (CVOTs) in high-risk patients, adding a BB to background LDL-lowering (statins, etc.), TG-lowering (specifically icosapent ethyl, which reduces ASCVD in patients with high TG, although apparently not via TG-lowering), and/or anti-diabetic (sodium glucose transport-2 inhibitors, SGLT2i, and glucagon-like protein-1 receptor agonists, GLP1-RA) treatments, as indicated in a given subject population.

G protein-coupled receptor kinase 5 (GRK5) contributes to impaired cardiac function and immune cell recruitment in post-ischemic heart failure

AIMS

Myocardial infarction (MI) is the most common cause of heart failure (HF) worldwide. G protein-coupled receptor kinase 5 (GRK5) is upregulated in failing human myocardium and promotes maladaptive cardiac hypertrophy in animal models. However, the role of GRK5 in ischemic heart disease is still unknown. In this study, we evaluated whether myocardial GRK5 plays a critical role post-MI in mice and included the examination of specific cardiac immune and inflammatory responses.

METHODS AND RESULTS

Cardiomyocyte-specific GRK5 overexpressing transgenic mice (TgGRK5) and non-transgenic littermate control (NLC) mice as well as cardiomyocyte-specific GRK5 knockout mice (GRK5cKO) and wild type (WT) were subjected to MI and, functional as well as structural changes together with outcomes were studied. TgGRK5 post-MI mice showed decreased cardiac function, augmented left ventricular dimension and decreased survival rate compared to NLC post-MI mice. Cardiac hypertrophy and fibrosis as well as fetal gene expression were increased post-MI in TgGRK5 compared to NLC mice. In TgGRK5 mice, GRK5 elevation produced immuno-regulators that contributed to the elevated and long-lasting leukocyte recruitment into the injured heart and ultimately to chronic cardiac inflammation. We found an increased presence of pro-inflammatory neutrophils and macrophages as well as neutrophils, macrophages and T-lymphocytes at 4-days and 8-weeks respectively post-MI in TgGRK5 hearts. Conversely, GRK5cKO mice were protected from ischemic injury and showed reduced early immune cell recruitment (predominantly monocytes) to the heart, improved contractility and reduced mortality compared to WT post-MI mice. Interestingly, cardiomyocyte-specific GRK2 transgenic mice did not share the same phenotype of TgGRK5 mice and did not have increased cardiac leukocyte migration and cytokine or chemokine production post-MI.

CONCLUSIONS

Our study shows that myocyte GRK5 has a crucial and GRK-selective role on the regulation of leucocyte infiltration into the heart, cardiac function and survival in a murine model of post-ischemic HF, supporting GRK5 inhibition as a therapeutic target for HF.

Immune cell β2-adrenergic receptors contribute to the development of heart failure

β-Adrenergic receptors (βARs) regulate normal and pathophysiological heart function through their impact on contractility. βARs are also regulators of immune function where they play a unique role depending on the disease condition and immune cell type. Emerging evidence suggests an important role for the β2AR subtype in regulating remodeling in the pathological heart; however, the importance of these responses has never been examined. In heart failure, catecholamines are elevated, leading to chronic βAR activation and contributing to the detrimental effects in the heart. We hypothesized that immune cell β2AR plays a critical role in the development of heart failure in response to chronic catecholamine elevations through their regulation of immune cell infiltration. To test this, chimeric mice were generated by performing bone marrow transplant (BMT) experiments using wild-type (WT) or β2AR knockout (KO) donors. WT and β2ARKO BMT mice were chronically administered the βAR agonist isoproterenol. Immune cell recruitment to the heart was examined by histology and flow cytometry. Numerous changes in immune cell recruitment were observed with isoproterenol administration in WT BMT mice including proinflammatory myeloid populations and lymphocytes with macrophages made up the majority of immune cells in the heart and which were absent in β2ARKO BMT animal. β2ARKO BMT mice had decreased cardiomyocyte death, hypertrophy, and interstitial fibrosis following isoproterenol treatment, culminating in improved function. These findings demonstrate an important role for immune cell β2AR expression in the heart's response to chronically elevated catecholamines.NEW & NOTEWORTHY Immune cell β2-adrenergic receptors (β2ARs) are important for proinflammatory macrophage infiltration to the heart in a chronic isoproterenol administration model of heart failure. Mice lacking immune cell β2AR have decreased immune cell infiltration to their heart, primarily proinflammatory macrophage populations. This decrease culminated to decreased cardiac injury with lessened cardiomyocyte death, decreased interstitial fibrosis and hypertrophy, and improved function demonstrating that β2AR regulation of immune responses plays an important role in the heart's response to persistent βAR stimulation.

A Dual Role for Death Receptor 5 in Regulating Cardiac Fibroblast Function

The fibrotic response is involved in nearly all forms of heart failure and dysregulated responses can lead to enhanced cardiac dysfunction. TNF-related apoptosis-inducing ligand (TRAIL) and its receptor, death receptor (DR) 5, are associated with multiple forms of heart failure, but their role in the heart is poorly defined. Our previous study identified DR5 expression on cardiac fibroblasts however, the impact of DR5 on fibroblast function remains unexplored. To investigate the role of DR5 in cardiac fibroblasts, a variety of fibroblast functions were examined following treatment with the endogenous ligand, TRAIL, or small molecule agonist, bioymifi. DR5 activation did not induce apoptosis in naïve fibroblasts but activated ERK1/2 signaling to increase proliferation. However, upon activation and differentiation to myofibroblasts, DR5 expression was elevated, and DR5 agonists induced caspase 3 activation resulting in myofibroblast apoptosis. To investigate the impact of DR5 regulation of fibroblasts in vivo, a chronic isoproterenol administration model of heart failure was used. Wild-type (WT) mice receiving isoproterenol had increased hypertrophy, cardiomyocyte death, and fibrosis and decreased contractility compared to vehicle treated animals. DR5 knockout (KO) mice had no overt baseline phenotype however, following isoproterenol infusion, increased cardiomyocyte death and hypertrophy in comparison to isoproterenol treated WT animals was observed. DR5KO mice had an augmented fibrotic response with isoproterenol treatment compared with WT, which corresponded with additional decreases in contractility. These findings identify a dual role for DR5 in cardiac fibroblast function through enhanced naïve fibroblast proliferation, which switches to a pro-apoptotic function upon differentiation to myofibroblasts. This is important in heart failure where DR5 activation suppresses maladaptive remodeling and may represent a novel therapeutic target for the treatment of heart failure.

Role of β-Adrenergic Receptors and Estrogen in Cardiac Repair after Myocardial Infarction: An Overview

Acute myocardial infarction (MI) is associated with an intense inflammatory response that is critical for cardiac repair but is also involved in the pathogenesis of adverse cardiac remodeling, i.e., the set of size, geometry, and structure changes that represent the structural substrate for the development of post-MI heart failure. Deciphering the pathophysiological mechanisms underlying cardiac repair after MI is, therefore, critical to favorably regulate cardiac wound repair and to prevent development of heart failure. Catecholamines and estrogen play an active role in regulating the inflammatory response in the infarcted area. For example, stress-induced catecholamines alter recruitment and trafficking of leukocytes to the heart. Additionally, estrogen affects rate of cardiac rupture during the acute phase of MI, as well as infarct size and survival in animal models of MI. In this review, we will summarize the role of β-adrenergic receptors and estrogen in cardiac repair after infarction in preclinical studies.

Targeting Inflammation after Myocardial Infarction: A Therapeutic Opportunity for Extracellular Vesicles?

After myocardial infarction (MI), a strong inflammatory response takes place in the heart to remove the dead tissue resulting from ischemic injury. A growing body of evidence suggests that timely resolution of this inflammatory process may aid in the prevention of adverse cardiac remodeling and heart failure post-MI. The present challenge is to find a way to stimulate this process without interfering with the reparative role of the immune system. Extracellular vesicles (EVs) are natural membrane particles that are released by cells and carry different macromolecules, including proteins and non-coding RNAs. In recent years, EVs derived from various stem and progenitor cells have been demonstrated to possess regenerative properties. They can provide cardioprotection via several mechanisms of action, including immunomodulation. In this review, we summarize the role of the innate immune system in post-MI healing. We then discuss the mechanisms by which EVs modulate cardiac inflammation in preclinical models of myocardial injury through regulation of monocyte influx and macrophage function. Finally, we provide suggestions for further optimization of EV-based therapy to improve its potential for the treatment of MI.

Association Between Premorbid Beta-Blocker Exposure and Sepsis Outcomes-The Beta-Blockers in European and Australian/American Septic Patients (BEAST) Study

OBJECTIVES

To examine the effect of premorbid β-blocker exposure on mortality and organ dysfunction in sepsis.

DESIGN

Retrospective observational study.

SETTING

ICUs in Australia, the Czech Republic, and the United States.

PATIENTS

Total of 4,086 critical care patients above 18 years old with sepsis between January 2014 and December 2018.

INTERVENTION

Premorbid beta-blocker exposure.

MEASUREMENTS AND MAIN RESULTS

One thousand five hundred fifty-six patients (38%) with premorbid β-blocker exposure were identified. Overall ICU mortality rate was 15.1%. In adjusted models, premorbid β-blocker exposure was associated with decreased ICU (adjusted odds ratio, 0.80; 95% CI, 0.66-0.97; p = 0.025) and hospital (adjusted odds ratio, 0.83; 95% CI, 0.71-0.99; p = 0.033) mortality. The risk reduction in ICU mortality of 16% was significant (hazard ratio, 0.84, 95% CI, 0.71-0.99; p = 0.037). In particular, exposure to noncardioselective β-blocker before septic episode was associated with decreased mortality. Sequential Organ Failure Assessment score analysis showed that premorbid β-blocker exposure had potential benefits in reducing respiratory and neurologic dysfunction.

CONCLUSIONS

This study suggests that β-blocker exposure prior to sepsis, especially to noncardioselective β blockers, may be associated with better outcome. The findings suggest prospective evaluation of β-blocker use in the management of sepsis.

Stress-induced differential gene expression in cardiac tissue

The stress response is adaptive and aims to guarantee survival. However, the persistence of a stressor can culminate in pathology. Catecholamines released as part of the stress response over activate beta adrenoceptors (β-AR) in the heart. Whether and how stress affects the expression of components of the intracellular environment in the heart is still, however, unknown. This paper used microarray to analyze the gene expression in the left ventricle wall of rats submitted to foot shock stress, treated or not treated with the selective β₂-AR antagonist ICI118,551 (ICI), compared to those of non-stressed rats also treated or not with ICI, respectively. The main findings were that stress induces changes in gene expression in the heart and that β₂-AR plays a role in this process. The vast majority of genes disregulated by stress were exclusive for only one of the comparisons, indicating that, in the same stressful situation, the profile of gene expression in the heart is substantially different when the β₂-AR is active or when it is blocked. Stress induced alterations in the expression of such a large number of genes seems to be part of stress-induced adaptive mechanism.

Systemic administration of a β2-adrenergic receptor agonist reduces mechanical allodynia and suppresses the immune response to surgery in a rat model of persistent post-incisional hypersensitivity

Beta 2 adrenergic receptor (β2 AR) activation in the central and peripheral nervous system has been implicated in nociceptive processing in acute and chronic pain settings with anti-inflammatory and anti-allodynic effects of β2-AR mimetics reported in several pain states. In the current study, we examined the therapeutic efficacy of the β2-AR agonist clenbuterol in a rat model of persistent postsurgical hypersensitivity induced by disruption of descending noradrenergic signaling in rats with plantar incision. We used growth curve modeling of ipsilateral mechanical paw withdrawal thresholds following incision to examine effects of treatment on postoperative trajectories. Depletion of spinal noradrenergic neurons delayed recovery of hypersensitivity following incision evident as a flattened slope compared to non-depleted rats (-1.8 g/day with 95% CI -2.4 to -1.085, p < 0.0001). Chronic administration of clenbuterol reduced mechanical hypersensitivity evident as a greater initial intercept in noradrenergic depleted (6.2 g with 95% CI 1.6 to 10.8, p = 0.013) and non-depleted rats (5.4 g with 95% CI 1.2 to 9.6, p = 0.018) with plantar incision compared to vehicle treated rats. Despite a persistent reduction in mechanical hypersensitivity, clenbuterol did not alter the slope of recovery when modeled over several days (p = 0.053) or five weeks in depleted rats (p = 0.64). Systemic clenbuterol suppressed the enhanced microglial activation in depleted rats and reduced the density of macrophage at the site of incision. Direct spinal infusion of clenbuterol failed to reduce mechanical hypersensitivity in depleted rats with incision suggesting that beneficial effects of β2-AR stimulation in this model are largely peripherally mediated. Lastly, we examined β2-AR distribution in the spinal cord and skin using in-situ hybridization and IHC. These data add to our understanding of the role of β2-ARs in the nervous system on hypersensitivity after surgical incision and extend previously observed anti-inflammatory actions of β2-AR agonists to models of surgical injury.

Recent Advances in GPCR-Regulated Leukocyte Responses during Acute Cardiac Injury

Following acute cardiac injury such as myocardial infarction (MI), the controlled activation and recruitment of various leukocytes to the site of tissue damage significantly impacts chronic changes to cardiac structure and function, and ultimately host survival. While recent research has focused primarily on how leukocytes respond to injury, understanding how to effectively modulate their responsiveness to dampen maladaptive inflammation and promote repair processes is not yet fully understood. The complex spatio-temporal migration and activation of leukocytes are largely controlled by various chemokines and their cognate receptors, belonging to the G protein-coupled receptor (GPCR) family. Beyond chemokine receptors, leukocytes express a host of additional GPCRs that have recently been shown to regulate their responsiveness to cardiac injury. In this minireview, we will briefly discuss the impact of chemokine receptors on leukocyte behaviour, with subsequent focus on the most recent advancements in understanding the impact and therapeutic potential of other GPCR classes on leukocyte responses after acute cardiac injury.

β2-Adrenergic Receptors Increase Cardiac Fibroblast Proliferation Through the Gαs/ERK1/2-Dependent Secretion of Interleukin-6

Fibroblasts are an important resident cell population in the heart involved in maintaining homeostasis and structure during normal conditions. They are also crucial in disease states for sensing signals and initiating the appropriate repair responses to maintain the structural integrity of the heart. This sentinel role of cardiac fibroblasts occurs, in part, through their ability to secrete cytokines. β-adrenergic receptors (βAR) are also critical regulators of cardiac function in the normal and diseased state and a major therapeutic target clinically. βAR are known to influence cytokine secretion in various cell types and they have been shown to be involved in cytokine production in the heart, but their role in regulating cytokine production in cardiac fibroblasts is not well understood. Thus, we hypothesized that βAR activation on cardiac fibroblasts modulates cytokine production to influence fibroblast function. Using primary fibroblast cultures from neonatal rats and adult mice, increased interleukin (IL)-6 expression and secretion occurred following β2AR activation. The use of pharmacological inhibitors and genetic manipulations showed that IL-6 elevations occurred through the Gαs-mediated activation of ERK1/2 and resulted in increased fibroblast proliferation. In vivo, a lack of β2AR resulted in increased infarct size following myocardial infarction and impaired wound closure in a murine dermal wound healing assay. These findings identify an important role for β2AR in regulating fibroblast proliferation through Gαs/ERK1/2-dependent alterations in IL-6 and may lead to the development of improved heart failure therapies through targeting fibrotic function of β2AR.

β1 adrenoceptor antibodies induce myocardial apoptosis via inhibiting PGC-1α-related pathway

Background

Peripartum cardiomyopathy (PPCM) is life-threatening heart disease. However, the causes and pathogenesis of PPCM remain unclear. Previous studies found that β1 adrenoceptor antibodies (β1AA) had possible involvement in the development of PPCM. In the present study, we determined the potential relationship between PPCM and β1AA, including the mechanism of β1AA leading to PPCM.

Methods

We extracted the β1AA from the postpartum Wistar rats that were injected by the antigen peptide segment of the β1 adrenoceptor to produce PPCM. We tested the effects of β1AA on H9C2 cell line by CCK-8, LDH, TUNEL, SA-ELISA, qRT-PCR, and western blot methods. Furthermore, PGC-1α was overexpressed to rescue the effect of β1AA on H9C2 cells.

Results

We found that the extracted β1AA induced apoptosis of cardiac myocytes of H9C2 cell line. Moreover, the expression of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), which is a master regulator of mitochondrial metabolism, and its downstream transcript vascular endothelial growth factor (VEGF) got decreased in H9C2 cells after β1AA treatment. In addition, the effect of β1AA could be inhibited by atenolol, the antagonist of β1 adrenoceptors (β1AR) and imitated by isoprenaline, the agonist of β1AR. Furthermore, overexpression of PGC-1α in the H9C2 cells rescued the apoptosis of cells and inhibitory expression of VEGF induced by β1AA.

Conclusions

Our results suggest that the symptoms of PPCM due to myocardial cell apoptosis induced by β1AA inhibiting the PGC-1α-related pathway impairs mitochondrial energy metabolism. Therefore, our results uncover a previously unknown role of the β1AA pathway in the etiology of PPCM and provide a novel potential target for the treatment of PPCM.