Involvement of the TGF-β pathway in epithelial-mesenchymal transition promoted by the pulmonary microenvironment in Mycoplasma pneumoniae pneumonia.

Mycoplasma pneumoniae (MP), one of the smallest prokaryotic microorganisms capable of independent survival, causes respiratory tract infections and various extrapulmonary diseases. Mycoplasma pneumoniae pneumonia (MPP) is the most significant clinical manifestation, often leading to complications such as atelectasis and pulmonary fibrosis. We explored the role of the pulmonary microenvironment in regulating epithelial-mesenchymal transition (EMT) in MPP patients with atelectasis. Transcriptome sequencing revealed significant upregulation of pathways including transforming growth factor beta (TGF-β), tumor protein 53 (P53), protein kinase Hippo, Ras-proximate-1 or Ras-related protein 1 (Rap1), and members of class O forkhead box proteins (FoxO) in cells exposed to bronchoalveolar lavage fluid (BALF) from MPP patients with atelectasis. Among these, the TGF-β pathway exhibited the most pronounced changes in gene expression. Further analysis confirmed that BALF from these patients induced EMT in human bronchial epithelial cells and mouse lung tissues and that TGF-β receptor kinase inhibitor (TRKI) effectively reversed this process. In conclusion, the pulmonary microenvironment in MPP patients with atelectasis promotes EMT in the lungs, with TGF-β playing a key role in this process. This may represent a crucial mechanism contributing to pulmonary fibrosis, underscoring the need to focus on the pulmonary microenvironment and TGF-β-targeted therapies for the prevention and management of pulmonary fibrosis in these patients. [ABSTRACT FROM AUTHOR]