[Study of macrophage polarization on pulmonary fibrosis and signaling pathway]

Abstract

Macrophages are a group of immune cells with pluripotency and plasticity that can differentiate into different phenotypes under different microenvironments in vitro and in vivo. In the development of pulmonary fibrosis, there are alveolar macrophages and interstitial macrophages, which are polarized to different cell phenotypes at different stages of development. And their polarized phenotypes include M1 macrophages and M2 macrophages. In the inflammation early stages of pulmonary fibrosis, the increase of classical activated macrophages are helpful to clear pathogenic microorganisms and promote the progress of inflammation. In the fibrosis stage, the alternatively activated macrophages increased, which inhibiting the inflammatory reaction or directly promoting tissue fibrosis, on the other hand, it also promoting the fibrosis degradation. To clarify the polarization and polarization mechanisms of macrophages in pulmonary fibrosis will be conducive to the treatment of pulmonary fibrosis. In IPF, the polarization mechanism of M1 and M2 is closely related to TGF-β1/Smad. TGF-β1/Smad pathway plays an important regulatory role in liver fibrosis, renal fibrosis, myocardial fibrosis, scars, tumors and other diseases. Blocking the signaling of TGF-β1 by Smad3 and Smad4 is beneficial to inhibit the polarization of AM, which in turn helps to inhibit the progression of IPF.

Keywords: M1 macrophage; M2 macrophage; TGF-β1/Smad; macrophage polarization; pulmonary fibrosis.