Diversity of Macrophages in Lung Homeostasis and Diseases

Front Immunol. 2021 Sep 24:12:753940. doi: 10.3389/fimmu.2021.753940. eCollection 2021.

Abstract

Lung macrophages play important roles in the maintenance of homeostasis, pathogen clearance and immune regulation. The different types of pulmonary macrophages and their roles in lung diseases have attracted attention in recent years. Alveolar macrophages (AMs), including tissue-resident alveolar macrophages (TR-AMs) and monocyte-derived alveolar macrophages (Mo-AMs), as well as interstitial macrophages (IMs) are the major macrophage populations in the lung and have unique characteristics in both steady-state conditions and disease states. The different characteristics of these three types of macrophages determine the different roles they play in the development of disease. Therefore, it is important to fully understand the similarities and differences among these three types of macrophages for the study of lung diseases. In this review, we will discuss the physiological characteristics and unique functions of these three types of macrophages in acute and chronic lung diseases. We will also discuss possible methods to target macrophages in lung diseases.

Keywords: COVID-19; fibrosis; infection; inflammation; macrophage.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Animals
  • COVID-19 / immunology*
  • Homeostasis
  • Humans
  • Inflammation
  • Lung / immunology*
  • Lung Diseases / immunology*
  • Macrophages / immunology*
  • SARS-CoV-2 / physiology*