Proliferating SPP1/MERTK-expressing macrophages in idiopathic pulmonary fibrosis

A comprehensive understanding of the changes in gene expression in cell types involved in idiopathic pulmonary fibrosis (IPF) will shed light on the mechanisms underlying the loss of alveolar epithelial cells and development of honeycomb cysts and fibroblastic foci. We sought to understand changes in IPF lung cell transcriptomes and gain insight into innate immune aspects of pathogenesis. We investigated IPF pathogenesis using single-cell RNA-sequencing of fresh lung explants, comparing human IPF fibrotic lower lobes reflecting late disease, upper lobes reflecting early disease and normal lungs. IPF lower lobes showed increased fibroblasts, and basal, ciliated, goblet and club cells, but decreased alveolar epithelial cells, and marked alterations in inflammatory cells. We found three discrete macrophage subpopulations in normal and fibrotic lungs, one expressing monocyte markers, one highly expressing FABP4 and INHBA (FABP4hi), and one highly expressing SPP1 and MERTK (SPP1hi). SPP1hi macrophages in fibrotic lower lobes showed highly upregulated SPP1 and MERTK expression. Low-level local proliferation of SPP1hi macrophages in normal lungs was strikingly increased in IPF lungs. Co-localisation and causal modelling supported the role for these highly proliferative SPP1hi macrophages in activation of IPF myofibroblasts in lung fibrosis. These data suggest that SPP1hi macrophages contribute importantly to lung fibrosis in IPF, and that therapeutic strategies targeting MERTK and macrophage proliferation may show promise for treatment of this disease. By single-cell RNA-sequencing we identify three discrete pulmonary macrophage subsets, including one expressing highly upregulated SPP1 and proliferating in fibrotic IPF lower lobes, accompanied by marked deposition of osteopontin in the matrix http://bit.ly/2wIRNqF

[1]  A. Shilatifard,et al.  Single-Cell Transcriptomic Analysis of Human Lung Provides Insights into the Pathobiology of Pulmonary Fibrosis , 2019, American journal of respiratory and critical care medicine.

[2]  C. Hogaboam,et al.  Targeting of TAM Receptors Ameliorates Fibrotic Mechanisms in Idiopathic Pulmonary Fibrosis , 2018, American journal of respiratory and critical care medicine.

[3]  C. Miller,et al.  MerTK as a therapeutic target in glioblastoma , 2018, Neuro-oncology.

[4]  Wei Chen,et al.  SFRP2/DPP4 and FMO1/LSP1 Define Major Fibroblast Populations in Human Skin. , 2017, The Journal of investigative dermatology.

[5]  Daniel C. Lee,et al.  MerTK Cleavage on Resident Cardiac Macrophages Compromises Repair After Myocardial Ischemia Reperfusion Injury , 2017, Circulation research.

[6]  A. Shilatifard,et al.  Monocyte-derived alveolar macrophages drive lung fibrosis and persist in the lung over the life span , 2017, The Journal of experimental medicine.

[7]  R. Zini,et al.  Involvement of MAF/SPP1 axis in the development of bone marrow fibrosis in PMF patients , 2017, Leukemia.

[8]  Q. Ma,et al.  Osteopontin enhances multi-walled carbon nanotube-triggered lung fibrosis by promoting TGF-β1 activation and myofibroblast differentiation , 2017, Particle and Fibre Toxicology.

[9]  C. Weston,et al.  MerTK expressing hepatic macrophages promote the resolution of inflammation in acute liver failure , 2017, Gut.

[10]  B. Stripp,et al.  Single-cell RNA sequencing identifies diverse roles of epithelial cells in idiopathic pulmonary fibrosis. , 2016, JCI insight.

[11]  D. Bernlohr,et al.  FABP4/aP2 Regulates Macrophage Redox Signaling and Inflammasome Activation via Control of UCP2 , 2016, Molecular and Cellular Biology.

[12]  Ivana V. Yang,et al.  Idiopathic Pulmonary Fibrosis: A Genetic Disease That Involves Mucociliary Dysfunction of the Peripheral Airways. , 2016, Physiological reviews.

[13]  T. Stulnig,et al.  Osteopontin is a key player for local adipose tissue macrophage proliferation in obesity , 2016, Molecular metabolism.

[14]  A. Gaggar,et al.  Matrix Remodeling in Pulmonary Fibrosis and Emphysema. , 2016, American journal of respiratory cell and molecular biology.

[15]  G. Fredman,et al.  MerTK cleavage limits proresolving mediator biosynthesis and exacerbates tissue inflammation , 2016, Proceedings of the National Academy of Sciences.

[16]  A. Nimmerjahn,et al.  TAM receptors regulate multiple features of microglial physiology , 2016, Nature.

[17]  D. Bernlohr,et al.  Metabolic functions of FABPs—mechanisms and therapeutic implications , 2015, Nature Reviews Endocrinology.

[18]  Joon-Oh Park,et al.  MerTK is a novel therapeutic target in gastric cancer , 2015, Oncotarget.

[19]  J. Suttles,et al.  Uncoupling Lipid Metabolism from Inflammation through Fatty Acid Binding Protein-Dependent Expression of UCP2 , 2015, Molecular and Cellular Biology.

[20]  Mark R. Looney,et al.  Lineage-negative Progenitors Mobilize to Regenerate Lung Epithelium after Major Injury , 2014, Nature.

[21]  T. Poll,et al.  TAM receptors, Gas6, and protein S: roles in inflammation and hemostasis , 2014 .

[22]  N. Neff,et al.  Reconstructing lineage hierarchies of the distal lung epithelium using single cell RNA-seq , 2014, Nature.

[23]  Guy C. Brown,et al.  Microglial phagocytosis of live neurons , 2014, Nature Reviews Neuroscience.

[24]  H. Collard,et al.  Future directions in idiopathic pulmonary fibrosis research. An NHLBI workshop report. , 2014, American journal of respiratory and critical care medicine.

[25]  Bernard Malissen,et al.  Alveolar macrophages develop from fetal monocytes that differentiate into long-lived cells in the first week of life via GM-CSF , 2013, The Journal of experimental medicine.

[26]  F. Ginhoux,et al.  Minimal differentiation of classical monocytes as they survey steady-state tissues and transport antigen to lymph nodes. , 2013, Immunity.

[27]  P. Taylor,et al.  Tissue-resident macrophages , 2013, Nature Immunology.

[28]  M. Cybulsky,et al.  Faculty Opinions recommendation of Tissue-resident macrophages self-maintain locally throughout adult life with minimal contribution from circulating monocytes. , 2013 .

[29]  D. Schwartz,et al.  The Idiopathic Pulmonary Fibrosis Honeycomb Cyst Contains A Mucocilary Pseudostratified Epithelium , 2013, PloS one.

[30]  S. Gordon,et al.  Genetic programs expressed in resting and IL-4 alternatively activated mouse and human macrophages: similarities and differences. , 2013, Blood.

[31]  Guy C. Brown,et al.  Eaten alive! Cell death by primary phagocytosis: 'phagoptosis'. , 2012, Trends in biochemical sciences.

[32]  J. Pollard,et al.  A Lineage of Myeloid Cells Independent of Myb and Hematopoietic Stem Cells , 2012, Science.

[33]  M. Mayes,et al.  Osteopontin in Systemic Sclerosis and its Role in Dermal Fibrosis , 2012, The Journal of investigative dermatology.

[34]  S. Kato,et al.  Overexpression of Chitinase 3-Like 1/YKL-40 in Lung-Specific IL-18-Transgenic Mice, Smokers and COPD , 2011, PloS one.

[35]  P. Taylor,et al.  A quantifiable proliferative burst of tissue macrophages restores homeostatic macrophage populations after acute inflammation , 2011, European journal of immunology.

[36]  F. Finkelman,et al.  Local Macrophage Proliferation, Rather than Recruitment from the Blood, Is a Signature of TH2 Inflammation , 2011, Science.

[37]  B. Hogan,et al.  Notch-dependent differentiation of adult airway basal stem cells. , 2011, Cell stem cell.

[38]  S. Pendergrass,et al.  Interferon and alternative activation of monocyte/macrophages in systemic sclerosis-associated pulmonary arterial hypertension. , 2011, Arthritis and rheumatism.

[39]  T. Blackwell,et al.  Idiopathic Pulmonary Fibrosis: A Disorder of Epithelial Cell Dysfunction , 2011, The American journal of the medical sciences.

[40]  Jean Wu,et al.  Osteopontin Overproduction Is Associated with Progression of Glomerular Fibrosis in a Rat Model of Anti-Glomerular Basement Membrane Glomerulonephritis , 2010, American Journal of Nephrology.

[41]  E. White,et al.  Targeted injury of type II alveolar epithelial cells induces pulmonary fibrosis. , 2010, American journal of respiratory and critical care medicine.

[42]  Scott H. Randell,et al.  Basal cells as stem cells of the mouse trachea and human airway epithelium , 2009, Proceedings of the National Academy of Sciences.

[43]  R. Flavell,et al.  Role of breast regression protein 39 (BRP-39)/chitinase 3-like-1 in Th2 and IL-13–induced tissue responses and apoptosis , 2009, The Journal of experimental medicine.

[44]  P. Zahradka,et al.  Novel role for osteopontin in cardiac fibrosis. , 2008, Circulation research.

[45]  G. Lemke,et al.  Macrophages and Dendritic Cells Use Different Axl/Mertk/Tyro3 Receptors in Clearance of Apoptotic Cells1 , 2007, The Journal of Immunology.

[46]  B. Varnum,et al.  A soluble form of the Mer receptor tyrosine kinase inhibits macrophage clearance of apoptotic cells and platelet aggregation. , 2007, Blood.

[47]  J. Horowitz,et al.  Evolving concepts of apoptosis in idiopathic pulmonary fibrosis. , 2006, Proceedings of the American Thoracic Society.

[48]  Naftali Kaminski,et al.  Up-Regulation and Profibrotic Role of Osteopontin in Human Idiopathic Pulmonary Fibrosis , 2005, PLoS medicine.

[49]  W. Kuziel,et al.  C‐C chemokine receptor 2 (CCR2) deficiency improves bleomycin‐induced pulmonary fibrosis by attenuation of both macrophage infiltration and production of macrophage‐derived matrix metalloproteinases , 2004, The Journal of pathology.

[50]  L. Liaw,et al.  Altered bleomycin-induced lung fibrosis in osteopontin-deficient mice. , 2004, American journal of physiology. Lung cellular and molecular physiology.

[51]  W. Hsueh,et al.  Osteopontin modulates angiotensin II-induced fibrosis in the intact murine heart. , 2004, Journal of the American College of Cardiology.

[52]  S. Phan,et al.  Dual Roles of IL-4 in Lung Injury and Fibrosis1 , 2003, The Journal of Immunology.

[53]  J. Rodríguez-Fernández,et al.  DC-SIGN (CD209) Expression Is IL-4 Dependent and Is Negatively Regulated by IFN, TGF-β, and Anti-Inflammatory Agents1 , 2002, The Journal of Immunology.

[54]  D. Weissman,et al.  Constitutive and induced expression of DC‐SIGN on dendritic cell and macrophage subpopulations in situ and in vitro , 2002, Journal of leukocyte biology.

[55]  R. Homer,et al.  Interleukin-13 Induces Tissue Fibrosis by Selectively Stimulating and Activating Transforming Growth Factor β1 , 2001, The Journal of experimental medicine.

[56]  Jeffrey B. Boord,et al.  Lack of macrophage fatty-acid–binding protein aP2 protects mice deficient in apolipoprotein E against atherosclerosis , 2001, Nature Medicine.

[57]  R. Scott,et al.  Phagocytosis and clearance of apoptotic cells is mediated by MER , 2001, Nature.

[58]  Kazuhisa Takahashi,et al.  Role of osteopontin in the pathogenesis of bleomycin-induced pulmonary fibrosis. , 2001, American journal of respiratory cell and molecular biology.

[59]  V. Fadok,et al.  Macrophages that have ingested apoptotic cells in vitro inhibit proinflammatory cytokine production through autocrine/paracrine mechanisms involving TGF-beta, PGE2, and PAF. , 1998, The Journal of clinical investigation.

[60]  R. Virmani,et al.  Aortic endothelial cells regulate proliferation of human monocytes in vitro via a mechanism synergistic with macrophage colony-stimulating factor. Convergence at the cyclin E/p27(Kip1) regulatory checkpoint. , 1997, The Journal of clinical investigation.

[61]  W. Janssen,et al.  Deletion of c‐FLIP from CD11bhi Macrophages Prevents Development of Bleomycin‐induced Lung Fibrosis , 2018, American journal of respiratory cell and molecular biology.

[62]  S. Tohda,et al.  Effects of MERTK Inhibitors UNC569 and UNC1062 on the Growth of Acute Myeloid Leukaemia Cells. , 2018, Anticancer research.