The Delta fbpA mutant derived from Mycobacterium tuberculosis H37Rv has an enhanced susceptibility to intracellular antimicrobial oxidative mechanisms, undergoes limited phagosome maturation and activates macrophages and dendritic cells

Cell Microbiol. 2008 Jun;10(6):1286-303. doi: 10.1111/j.1462-5822.2008.01126.x. Epub 2008 Jan 31.

Abstract

Mycobacterium tuberculosis H37Rv (Mtb) excludes phagocyte oxidase (phox) and inducible nitric oxide synthase (iNOS) while preventing lysosomal fusion in macrophages (MPhis). The antigen 85A deficient (Delta fbpA) mutant of Mtb was vaccinogenic in mice and the mechanisms of attenuation were compared with MPhis infected with H37Rv and BCG. Delta fbpA contained reduced amounts of trehalose 6, 6, dimycolate and induced minimal levels of SOCS-1 in MPhis. Blockade of oxidants enhanced the growth of Delta fbpA in MPhis that correlated with increased colocalization with phox and iNOS. Green fluorescent protein-expressing strains within MPhis or purified phagosomes were analysed for endosomal traffick with immunofluorescence and Western blot. Delta fbpA phagosomes were enriched for rab5, rab11, LAMP-1 and Hck suggesting enhanced fusion with early, recycling and late endosomes in MPhis compared with BCG or H37Rv. Delta fbpA phagosomes were thus more mature than H37Rv or BCG although, they failed to acquire rab7 and CD63 preventing lysosomal fusion. Finally, Delta fbpA infected MPhis and dendritic cells (DCs) showed an enhanced MHC-II and CD1d expression and primed immune T cells to release more IFN-gamma compared with those infected with BCG and H37Rv. Delta fbpA was thus more immunogenic in MPhis and DCs because of an enhanced susceptibility to oxidants and increased maturation.

Publication types

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

MeSH terms

  • Acyltransferases / genetics*
  • Animals
  • Antigens, Bacterial / genetics*
  • Antigens, CD1 / metabolism
  • Antigens, CD1d
  • Cells, Cultured
  • Dendritic Cells / metabolism*
  • Dendritic Cells / microbiology
  • Endosomes / metabolism
  • GTP-Binding Proteins / metabolism
  • Histocompatibility Antigens Class II / metabolism
  • Interferon-gamma / biosynthesis
  • Lysosome-Associated Membrane Glycoproteins / metabolism
  • Macrophages / metabolism*
  • Macrophages / microbiology
  • Mice
  • Mice, Inbred C57BL
  • Mycobacterium tuberculosis / pathogenicity
  • Mycobacterium tuberculosis / physiology*
  • Nitric Oxide Synthase Type II / metabolism*
  • Oxidoreductases / metabolism*
  • Phagosomes / metabolism*
  • Point Mutation
  • Proto-Oncogene Proteins c-hck / metabolism
  • Reactive Oxygen Species / metabolism
  • Signal Transduction
  • Suppressor of Cytokine Signaling 1 Protein
  • Suppressor of Cytokine Signaling Proteins / metabolism*
  • T-Lymphocytes / immunology
  • T-Lymphocytes / metabolism
  • Terminal Repeat Sequences / genetics*
  • Tuberculosis / immunology
  • Tuberculosis / microbiology
  • rab5 GTP-Binding Proteins / metabolism

Substances

  • Antigens, Bacterial
  • Antigens, CD1
  • Antigens, CD1d
  • Histocompatibility Antigens Class II
  • Lamp1 protein, mouse
  • Lysosome-Associated Membrane Glycoproteins
  • Reactive Oxygen Species
  • Socs1 protein, mouse
  • Suppressor of Cytokine Signaling 1 Protein
  • Suppressor of Cytokine Signaling Proteins
  • Interferon-gamma
  • Oxidoreductases
  • Nitric Oxide Synthase Type II
  • Acyltransferases
  • antigen 85A, Mycobacterium tuberculosis
  • Hck protein, mouse
  • Proto-Oncogene Proteins c-hck
  • GTP-Binding Proteins
  • rab5 GTP-Binding Proteins