Single-Cell RNA Sequencing Reveals Metabolic Stress-Dependent Activation of Cardiac Macrophages in a Model of Dyslipidemia-Induced Diastolic Dysfunction. Circulation BACKGROUND:Metabolic distress is often associated with heart failure with preserved ejection fraction (HFpEF) and represents a therapeutic challenge. Metabolism-induced systemic inflammation links comorbidities with HFpEF. How metabolic changes affect myocardial inflammation in the context of HFpEF is not known. METHODS:We found that ApoE knockout mice fed a Western diet recapitulate many features of HFpEF. Single-cell RNA sequencing was used for expression analysis of CD45 cardiac cells to evaluate the involvement of inflammation in diastolic dysfunction. We focused bioinformatics analysis on macrophages, obtaining high-resolution identification of subsets of these cells in the heart, enabling us to study the outcomes of metabolic distress on the cardiac macrophage infiltrate and to identify a macrophage-to-cardiomyocyte regulatory axis. To test whether a clinically relevant sodium glucose cotransporter-2 inhibitor could ameliorate the cardiac immune infiltrate profile in our model, mice were randomized to receive the sodium glucose cotransporter-2 inhibitor dapagliflozin or vehicle for 8 weeks. RESULTS:ApoE knockout mice fed a Western diet presented with reduced diastolic function, reduced exercise tolerance, and increased pulmonary congestion associated with cardiac lipid overload and reduced polyunsaturated fatty acids. The main immune cell types infiltrating the heart included 4 subpopulations of resident and monocyte-derived macrophages, determining a proinflammatory profile exclusively in ApoE knockout- Western diet mice. Lipid overload had a direct effect on inflammatory gene activation in macrophages, mediated through endoplasmic reticulum stress pathways. Investigation of the macrophage-to-cardiomyocyte regulatory axis revealed the potential effects on cardiomyocytes of multiple inflammatory cytokines secreted by macrophages, affecting pathways such as hypertrophy, fibrosis, and autophagy. Finally, we describe an anti-inflammatory effect of sodium glucose cotransporter-2 inhibitor in this model. CONCLUSIONS:Using single-cell RNA sequencing , in a model of diastolic dysfunction driven by hyperlipidemia, we have determined the effects of metabolic distress on cardiac inflammatory cells, in particular on macrophages, and suggest sodium glucose cotransporter-2 inhibitors as potential therapeutic agents for the targeting of a specific phenotype of HFpEF. 10.1161/CIRCULATIONAHA.122.062984

Pro-Angiogenic Macrophage Phenotype to Promote Myocardial Repair. Ferraro Bartolo,Leoni Giovanna,Hinkel Rabea,Ormanns Steffen,Paulin Nicole,Ortega-Gomez Almudena,Viola Joana R,de Jong Renske,Bongiovanni Dario,Bozoglu Tarik,Maas Sanne L,D'Amico Michele,Kessler Thorsten,Zeller Tanja,Hristov Michael,Reutelingsperger Chris,Sager Hendrik B,Döring Yvonne,Nahrendorf Matthias,Kupatt Christian,Soehnlein Oliver Journal of the American College of Cardiology BACKGROUND:Heart failure following myocardial infarction (MI) remains one of the major causes of death worldwide, and its treatment is a crucial challenge of cardiovascular medicine. An attractive therapeutic strategy is to stimulate endogenous mechanisms of myocardial regeneration. OBJECTIVES:This study evaluates the potential therapeutic treatment with annexin A1 (AnxA1) to induce cardiac repair after MI. METHODS:AnxA1 knockout (AnxA1) and wild-type mice underwent MI induced by ligation of the left anterior descending coronary artery. Cardiac functionality was assessed by longitudinal echocardiographic measurements. Histological, fluorescence-activated cell sorting, dot blot analysis, and in vitro/ex vivo studies were used to assess the myocardial neovascularization, macrophage content, and activity in response to AnxA1. RESULTS:AnxA1 mice showed a reduced cardiac functionality and an expansion of proinflammatory macrophages in the ischemic area. Cardiac macrophages from AnxA1 mice exhibited a dramatically reduced ability to release the proangiogenic mediator vascular endothelial growth factor (VEGF)-A. However, AnxA1 treatment enhanced VEGF-A release from cardiac macrophages, and its delivery in vivo markedly improved cardiac performance. The positive effect of AnxA1 treatment on cardiac performance was abolished in wild-type mice transplanted with bone marrow derived from Cxcr1creVegf or in mice depleted of macrophages. Similarly, cardioprotective effects of AnxA1 were obtained in pigs in which full-length AnxA1 was overexpressed by use of a cardiotropic adeno-associated virus. CONCLUSIONS:AnxA1 has a direct action on cardiac macrophage polarization toward a pro-angiogenic, reparative phenotype. AnxA1 stimulated cardiac macrophages to release high amounts of VEGF-A, thus inducing neovascularization and cardiac repair. 10.1016/j.jacc.2019.03.503

Origin and functions of tissue macrophages. Immunity Macrophages are distributed in tissues throughout the body and contribute to both homeostasis and disease. Recently, it has become evident that most adult tissue macrophages originate during embryonic development and not from circulating monocytes. Each tissue has its own composition of embryonically derived and adult-derived macrophages, but it is unclear whether macrophages of distinct origins are functionally interchangeable or have unique roles at steady state. This new understanding also prompts reconsideration of the function of circulating monocytes. Classical Ly6c(hi) monocytes patrol the extravascular space in resting organs, and Ly6c(lo) nonclassical monocytes patrol the vasculature. Inflammation triggers monocytes to differentiate into macrophages, but whether resident and newly recruited macrophages possess similar functions during inflammation is unclear. Here, we define the tools used for identifying the complex origin of tissue macrophages and discuss the relative contributions of tissue niche versus ontological origin to the regulation of macrophage functions during steady state and inflammation. 10.1016/j.immuni.2014.06.013

A Network of Macrophages Supports Mitochondrial Homeostasis in the Heart. Nicolás-Ávila José A,Lechuga-Vieco Ana V,Esteban-Martínez Lorena,Sánchez-Díaz María,Díaz-García Elena,Santiago Demetrio J,Rubio-Ponce Andrea,Li Jackson LiangYao,Balachander Akhila,Quintana Juan A,Martínez-de-Mena Raquel,Castejón-Vega Beatriz,Pun-García Andrés,Través Paqui G,Bonzón-Kulichenko Elena,García-Marqués Fernando,Cussó Lorena,A-González Noelia,González-Guerra Andrés,Roche-Molina Marta,Martin-Salamanca Sandra,Crainiciuc Georgiana,Guzmán Gabriela,Larrazabal Jagoba,Herrero-Galán Elías,Alegre-Cebollada Jorge,Lemke Greg,Rothlin Carla V,Jimenez-Borreguero Luis Jesús,Reyes Guillermo,Castrillo Antonio,Desco Manuel,Muñoz-Cánoves Pura,Ibáñez Borja,Torres Miguel,Ng Lai Guan,Priori Silvia G,Bueno Héctor,Vázquez Jesús,Cordero Mario D,Bernal Juan A,Enríquez José A,Hidalgo Andrés Cell Cardiomyocytes are subjected to the intense mechanical stress and metabolic demands of the beating heart. It is unclear whether these cells, which are long-lived and rarely renew, manage to preserve homeostasis on their own. While analyzing macrophages lodged within the healthy myocardium, we discovered that they actively took up material, including mitochondria, derived from cardiomyocytes. Cardiomyocytes ejected dysfunctional mitochondria and other cargo in dedicated membranous particles reminiscent of neural exophers, through a process driven by the cardiomyocyte's autophagy machinery that was enhanced during cardiac stress. Depletion of cardiac macrophages or deficiency in the phagocytic receptor Mertk resulted in defective elimination of mitochondria from the myocardial tissue, activation of the inflammasome, impaired autophagy, accumulation of anomalous mitochondria in cardiomyocytes, metabolic alterations, and ventricular dysfunction. Thus, we identify an immune-parenchymal pair in the murine heart that enables transfer of unfit material to preserve metabolic stability and organ function. VIDEO ABSTRACT. 10.1016/j.cell.2020.08.031

Resident cardiac macrophages mediate adaptive myocardial remodeling. Immunity Cardiac macrophages represent a heterogeneous cell population with distinct origins, dynamics, and functions. Recent studies have revealed that C-C Chemokine Receptor 2 positive (CCR2) macrophages derived from infiltrating monocytes regulate myocardial inflammation and heart failure pathogenesis. Comparatively little is known about the functions of tissue resident (CCR2) macrophages. Herein, we identified an essential role for CCR2 macrophages in the chronically failing heart. Depletion of CCR2 macrophages in mice with dilated cardiomyopathy accelerated mortality and impaired ventricular remodeling and coronary angiogenesis, adaptive changes necessary to maintain cardiac output in the setting of reduced cardiac contractility. Mechanistically, CCR2 macrophages interacted with neighboring cardiomyocytes via focal adhesion complexes and were activated in response to mechanical stretch through a transient receptor potential vanilloid 4 (TRPV4)-dependent pathway that controlled growth factor expression. These findings establish a role for tissue-resident macrophages in adaptive cardiac remodeling and implicate mechanical sensing in cardiac macrophage activation. 10.1016/j.immuni.2021.07.003