Cigarette smoke attenuates phagocytic ability of macrophages through down-regulating Milk fat globule-EGF factor 8 (MFG-E8) expressions

Sci Rep. 2017 Feb 14:7:42642. doi: 10.1038/srep42642.

Abstract

Chronic obstructive pulmonary disease (COPD) is one of the most common inflammatory diseases resulting from habitual smoking. Impaired clearance of apoptotic cell by airway macrophages contributes to lung inflammation. Milk fat globule-EGF factor 8 (MFG-E8), as a link between apoptotic cells and phagocytes, facilitates clearance of apoptotic cells and attenuates inflammation. We sought to investigate altered expression and potential role of MFG-E8 in COPD. In this study, apoptosis was increased and the level of MFG-E8 was decreased while HMGB1 expression was increased in lung tissues of CS-exposed mice. Compared with CS-exposed WT mice, more apoptotic cells were accumulated in lung tissues of CS-exposed MFG-E8 deficiency mice. Exposure of a range of macrophages to cigarette smoke extract (CSE) resulted in decreased MFG-E8 expression. Administration of rmMFG-E8 ameliorated phagocytic ability of RAW264.7 cells and suppressed inflammatory response induced by CS-exposure. 10% CSE stimulation suppressed Rac1 membrane localization in RAW264.7 cells which was restored by administration of rmMFG-E8. MFG-E8 deficiency diminished uptake of apoptotic thymocytes by peritoneal macrophages upon CSE exposure. Overall, the findings in current work provide a novel target for diagnosing and treating COPD.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Surface / genetics*
  • Apoptosis / genetics
  • Cytokines / metabolism
  • Gene Expression Regulation*
  • HMGB1 Protein / genetics
  • HMGB1 Protein / metabolism
  • Inflammation Mediators
  • Lung / immunology
  • Lung / metabolism
  • Lung / pathology
  • Macrophages / immunology*
  • Macrophages / metabolism*
  • Mice
  • Milk Proteins / genetics*
  • Phagocytosis / immunology*
  • RAW 264.7 Cells
  • Smoking / adverse effects*
  • Thymocytes / immunology
  • Thymocytes / metabolism

Substances

  • Antigens, Surface
  • Cytokines
  • HMGB1 Protein
  • Inflammation Mediators
  • Mfge8 protein, mouse
  • Milk Proteins