Jeremie Joffre1, Stephane Potteaux1, Lynda Zeboudj1, Xavier Loyer1, Amir Boufenzer2, Ludivine Laurans1, Bruno Esposito1, Marie Vandestienne1, Saskia C A de Jager3, Carole Hénique1, Ivana Zlatanova1, Soraya Taleb1, Patrick Bruneval4, Alain Tedgui1, Ziad Mallat5, Sebastien Gibot6, Hafid Ait-Oufella7. 1. INSERM U970, Paris Cardiovascular Research Center, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France. 2. INOTREM SA, Nancy, France. 3. Laboratory for Experimental Cardiology, University Medical Center, Utrecht, the Netherlands. 4. INSERM U970, Paris Cardiovascular Research Center, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France; Department of Anatomopathology, Hôpital Européen Georges Pompidou, Assistance Publique-Hopitaux de Paris, Paris, France. 5. INSERM U970, Paris Cardiovascular Research Center, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France; Department of Medicine, Division of Cardiovascular Medicine, University of Cambridge, Cambridge, United Kingdom. 6. INSERM Unité mixte de Recherche-S1116, Faculté de Médecine, Université de Lorraine, Medical Intensive Care Unit, Hôpital Central, Nancy, France. 7. INSERM U970, Paris Cardiovascular Research Center, Paris, France; Université Paris Descartes, Sorbonne Paris Cité, Paris, France; Medical Intensive Care Unit, Hôpital Saint-Antoine, Assistance Publique-Hopitaux de Paris, Université Pierre-et-Marie Curie, Paris, France. Electronic address: hafid.aitoufella@inserm.fr.
Abstract
BACKGROUND: Innate immune responses activated through myeloid cells contribute to the initiation, progression, and complications of atherosclerosis in experimental models. However, the critical upstream pathways that link innate immune activation to foam cell formation are still poorly identified. OBJECTIVES: This study sought to investigate the hypothesis that activation of the triggering receptor expressed on myeloid cells (TREM-1) plays a determinant role in macrophage atherogenic responses. METHODS: After genetically invalidating Trem-1 in chimeric Ldlr-/-Trem-1-/- mice and double knockout ApoE-/-Trem-1-/- mice, we pharmacologically inhibited Trem-1 using LR12 peptide. RESULTS: Ldlr-/- mice reconstituted with bone marrow deficient for Trem-1 (Trem-1-/-) showed a strong reduction of atherosclerotic plaque size in both the aortic sinus and the thoracoabdominal aorta, and were less inflammatory compared to plaques of Trem-1+/+ chimeric mice. Genetic invalidation of Trem-1 led to alteration of monocyte recruitment into atherosclerotic lesions and inhibited toll-like receptor 4 (TLR 4)-initiated proinflammatory macrophage responses. We identified a critical role for Trem-1 in the upregulation of cluster of differentiation 36 (CD36), thereby promoting the formation of inflammatory foam cells. Genetic invalidation of Trem-1 in ApoE-/-/Trem-1-/- mice or pharmacological blockade of Trem-1 in ApoE-/- mice using LR-12 peptide also significantly reduced the development of atherosclerosis throughout the vascular tree, and lessened plaque inflammation. TREM-1 was expressed in human atherosclerotic lesions, mainly in lipid-rich areas with significantly higher levels of expression in atheromatous than in fibrous plaques. CONCLUSIONS: We identified TREM-1 as a major upstream proatherogenic receptor. We propose that TREM-1 activation orchestrates monocyte/macrophage proinflammatory responses and foam cell formation through coordinated and combined activation of CD36 and TLR4. Blockade of TREM-1 signaling may constitute an attractive novel and double-hit approach for the treatment of atherosclerosis.
BACKGROUND: Innate immune responses activated through myeloid cells contribute to the initiation, progression, and complications of atherosclerosis in experimental models. However, the critical upstream pathways that link innate immune activation to foam cell formation are still poorly identified. OBJECTIVES: This study sought to investigate the hypothesis that activation of the triggering receptor expressed on myeloid cells (TREM-1) plays a determinant role in macrophage atherogenic responses. METHODS: After genetically invalidating Trem-1 in chimeric Ldlr-/-Trem-1-/- mice and double knockout ApoE-/-Trem-1-/- mice, we pharmacologically inhibited Trem-1 using LR12 peptide. RESULTS: Ldlr-/- mice reconstituted with bone marrow deficient for Trem-1 (Trem-1-/-) showed a strong reduction of atherosclerotic plaque size in both the aortic sinus and the thoracoabdominal aorta, and were less inflammatory compared to plaques of Trem-1+/+ chimeric mice. Genetic invalidation of Trem-1 led to alteration of monocyte recruitment into atherosclerotic lesions and inhibited toll-like receptor 4 (TLR 4)-initiated proinflammatory macrophage responses. We identified a critical role for Trem-1 in the upregulation of cluster of differentiation 36 (CD36), thereby promoting the formation of inflammatory foam cells. Genetic invalidation of Trem-1 in ApoE-/-/Trem-1-/- mice or pharmacological blockade of Trem-1 in ApoE-/- mice using LR-12 peptide also significantly reduced the development of atherosclerosis throughout the vascular tree, and lessened plaque inflammation. TREM-1 was expressed in human atherosclerotic lesions, mainly in lipid-rich areas with significantly higher levels of expression in atheromatous than in fibrous plaques. CONCLUSIONS: We identified TREM-1 as a major upstream proatherogenic receptor. We propose that TREM-1 activation orchestrates monocyte/macrophage proinflammatory responses and foam cell formation through coordinated and combined activation of CD36 and TLR4. Blockade of TREM-1 signaling may constitute an attractive novel and double-hit approach for the treatment of atherosclerosis.
Authors: Zeqin Lian; Xiao-Yuan Dai Perrard; Xueying Peng; Joe L Raya; Alfredo A Hernandez; Collin G Johnson; William R Lagor; Henry J Pownall; Ron C Hoogeveen; Scott I Simon; Frank M Sacks; Christie M Ballantyne; Huaizhu Wu Journal: Arterioscler Thromb Vasc Biol Date: 2019-10-17 Impact factor: 8.311