Mycobacterium tuberculosis Rv3463 induces mycobactericidal activity in macrophages by enhancing phagolysosomal fusion and exhibits therapeutic potential

Sci Rep. 2019 Mar 12;9(1):4246. doi: 10.1038/s41598-019-38982-0.

Abstract

Macrophages are responsible for innate and adaptive immune response activation necessary for eliminating infections. Optimal activation of macrophages to phagocytize Mycobacterium tuberculosis is critical in anti-mycobacterial defense. Here, we identified a novel Rv3463 hypothetical protein that induces macrophage activation in Mtb culture filtrate. Recombinant Rv3463 activated mouse bone marrow-derived macrophages to induce the expression of surface molecules and secrete pro-inflammatory cytokines via the TLR2 and TLR4 pathways. Mitogen activated protein kinase, phospatidylinositol-4,5-bisphosphate 3-kinases, and the NF-κB signaling pathways are involved in Rv3463-mediated macrophage activation. Furthermore, Rv3463 induced bactericidal effects in Mtb-infected macrophages through phagosome maturation and phagolysosomal fusion enhanced by phospatidylinositol-4,5-bisphosphate 3-kinases and Ca2+ signaling pathways and exhibited therapeutic effects in a short-term Mtb-infection mouse model. Overexpression of Rv3463 in M. smegmatis caused rapid clearance of bacteria in macrophages and mice. Our study suggests that Rv3463 is a promising target for the development of post-exposure tuberculosis vaccines or adjunct immune-therapy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Bacterial / immunology*
  • Antigens, Bacterial / metabolism
  • Bacterial Proteins / immunology*
  • Bacterial Proteins / metabolism
  • Disease Models, Animal
  • Female
  • Humans
  • Lysosomes / immunology
  • Lysosomes / microbiology
  • Macrophage Activation
  • Macrophages / immunology*
  • Macrophages / microbiology
  • Mice
  • Mycobacterium tuberculosis / immunology*
  • Phagocytosis / immunology
  • Post-Exposure Prophylaxis / methods
  • Signal Transduction / immunology
  • THP-1 Cells
  • Toll-Like Receptor 2 / metabolism
  • Toll-Like Receptor 4 / metabolism
  • Tuberculosis / immunology
  • Tuberculosis / microbiology
  • Tuberculosis / prevention & control*
  • Tuberculosis Vaccines / immunology
  • Tuberculosis Vaccines / therapeutic use*
  • Vaccines, Subunit / immunology
  • Vaccines, Subunit / therapeutic use

Substances

  • Antigens, Bacterial
  • Bacterial Proteins
  • Toll-Like Receptor 2
  • Toll-Like Receptor 4
  • Tuberculosis Vaccines
  • Vaccines, Subunit