The human lung mucosa drives differential Mycobacterium tuberculosis infection outcome in the alveolar epithelium

Mucosal Immunol. 2019 May;12(3):795-804. doi: 10.1038/s41385-019-0156-2. Epub 2019 Mar 7.

Abstract

Mycobacterium tuberculosis (M.tb) is deposited into the alveolus where it first encounters the alveolar lining fluid (ALF) prior contacts host cells. We demonstrated that M.tb-exposure to human ALF alters its cell surface, driving better M.tb infection control by professional phagocytes. Contrary to these findings, our results with non-professional phagocytes alveolar epithelial cells (ATs) define two distinct subsets of human ALFs; where M.tb exposure to Low (L)-ALF or High(H)-ALF results in low or high intracellular bacterial growth rates in ATs, respectively. H-ALF exposed-M.tb growth within ATs was independent of M.tb-uptake, M.tb-trafficking, and M.tb-infection induced cytotoxicity; however, it was associated with enhanced bacterial replication within LAMP-1+/ABCA1+ compartments. H-ALF exposed-M.tb infection of ATs decreased AT immune mediator production, decreased AT surface adhesion expression, and downregulated macrophage inflammatory responses. Composition analysis of H-ALF vs. L-ALF showed H-ALF with higher protein tyrosine nitration and less functional ALF-innate proteins important in M.tb pathogenesis. Replenishment of H-ALF with functional ALF-innate proteins reversed the H-ALF-M.tb growth rate to the levels observed for L-ALF-M.tb. These results indicate that dysfunctionality of innate proteins in the H-ALF phenotype promotes M.tb replication within ATs, while limiting inflammation and phagocyte activation, thus potentiating ATs as a reservoir for M.tb replication and survival.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • A549 Cells
  • Apoptosis
  • Cell Adhesion
  • Cytotoxicity, Immunologic
  • DNA Replication
  • DNA, Bacterial / genetics*
  • Epithelial Cells / immunology
  • Epithelial Cells / physiology*
  • Humans
  • Immunity, Innate
  • Lung / microbiology
  • Lung / pathology*
  • Mycobacterium tuberculosis / physiology*
  • Phagocytosis
  • Pulmonary Alveoli / immunology
  • Pulmonary Alveoli / pathology*
  • Respiratory Mucosa / immunology*
  • Tuberculosis, Pulmonary / immunology*

Substances

  • DNA, Bacterial