Novel role of extracellular matrix protein 1 (ECM1) in cardiac aging and myocardial infarction

PLoS One. 2019 Feb 21;14(2):e0212230. doi: 10.1371/journal.pone.0212230. eCollection 2019.

Abstract

Introduction: The prevalence of heart failure increases in the aging population and following myocardial infarction (MI), yet the extracellular matrix (ECM) remodeling underpinning the development of aging- and MI-associated cardiac fibrosis remains poorly understood. A link between inflammation and fibrosis in the heart has long been appreciated, but has mechanistically remained undefined. We investigated the expression of a novel protein, extracellular matrix protein 1 (ECM1) in the aging and infarcted heart.

Methods: Young adult (3-month old) and aging (18-month old) C57BL/6 mice were assessed. Young mice were subjected to left anterior descending artery-ligation to induce MI, or transverse aortic constriction (TAC) surgery to induce pressure-overload cardiomyopathy. Left ventricle (LV) tissue was collected early and late post-MI/TAC. Bone marrow cells (BMCs) were isolated from young healthy mice, and subject to flow cytometry. Human cardiac fibroblast (CFb), myocyte, and coronary artery endothelial & smooth muscle cell lines were cultured; human CFbs were treated with recombinant ECM1. Primary mouse CFbs were cultured and treated with recombinant angiotensin-II or TGF-β1. Immunoblotting, qPCR and mRNA fluorescent in-situ hybridization (mRNA-FISH) were conducted on LV tissue and cells.

Results: ECM1 expression was upregulated in the aging LV, and in the infarct zone of the LV early post-MI. No significant differences in ECM1 expression were found late post-MI or at any time-point post-TAC. ECM1 was not expressed in any resident cardiac cells, but ECM1 was highly expressed in BMCs, with high ECM1 expression in granulocytes. Flow cytometry of bone marrow revealed ECM1 expression in large granular leucocytes. mRNA-FISH revealed that ECM1 was indeed expressed by inflammatory cells in the infarct zone at day-3 post-MI. ECM1 stimulation of CFbs induced ERK1/2 and AKT activation and collagen-I expression, suggesting a pro-fibrotic role.

Conclusions: ECM1 expression is increased in ageing and infarcted hearts but is not expressed by resident cardiac cells. Instead it is expressed by bone marrow-derived granulocytes. ECM1 is sufficient to induce cardiac fibroblast stimulation in vitro. Our findings suggest ECM1 is released from infiltrating inflammatory cells, which leads to cardiac fibroblast stimulation and fibrosis in aging and MI. ECM1 may be a novel intermediary between inflammation and fibrosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aging / metabolism*
  • Aging / pathology
  • Animals
  • Extracellular Matrix Proteins / biosynthesis*
  • Female
  • Gene Expression Regulation*
  • Heart Ventricles / metabolism
  • Heart Ventricles / pathology
  • Humans
  • Male
  • Mice
  • Myocardial Infarction / metabolism*
  • Myocardial Infarction / pathology
  • Myocardium / metabolism*
  • Myocardium / pathology

Substances

  • ECM1 protein, human
  • Ecm1 protein, mouse
  • Extracellular Matrix Proteins

Grant support

This work was supported by the John Hunter Charitable Trust [grant number G1800510], awarded to S.H. To my knowledge there is no URL for the funding source website. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.