Mycobacterium tuberculosis activates human macrophage peroxisome proliferator-activated receptor gamma linking mannose receptor recognition to regulation of immune responses

J Immunol. 2010 Jul 15;185(2):929-42. doi: 10.4049/jimmunol.1000866. Epub 2010 Jun 16.

Abstract

Mycobacterium tuberculosis enhances its survival in macrophages by suppressing immune responses in part through its complex cell wall structures. Peroxisome proliferator-activated receptor gamma (PPARgamma), a nuclear receptor superfamily member, is a transcriptional factor that regulates inflammation and has high expression in alternatively activated alveolar macrophages and macrophage-derived foam cells, both cell types relevant to tuberculosis pathogenesis. In this study, we show that virulent M. tuberculosis and its cell wall mannose-capped lipoarabinomannan induce PPARgamma expression through a macrophage mannose receptor-dependent pathway. When activated, PPARgamma promotes IL-8 and cyclooxygenase 2 expression, a process modulated by a PPARgamma agonist or antagonist. Upstream, MAPK-p38 mediates cytosolic phospholipase A(2) activation, which is required for PPARgamma ligand production. The induced IL-8 response mediated by mannose-capped lipoarabinomannan and the mannose receptor is independent of TLR2 and NF-kappaB activation. In contrast, the attenuated Mycobacterium bovis bacillus Calmette-Guérin induces less PPARgamma and preferentially uses the NF-kappaB-mediated pathway to induce IL-8 production. Finally, PPARgamma knockdown in human macrophages enhances TNF production and controls the intracellular growth of M. tuberculosis. These data identify a new molecular pathway that links engagement of the mannose receptor, an important pattern recognition receptor for M. tuberculosis, with PPARgamma activation, which regulates the macrophage inflammatory response, thereby playing a role in tuberculosis pathogenesis.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Anilides / pharmacology
  • Blotting, Western
  • Cells, Cultured
  • Cyclooxygenase 2 / metabolism
  • Enzyme Activation / drug effects
  • Host-Pathogen Interactions / immunology
  • Humans
  • Interleukin-8 / metabolism
  • Lectins, C-Type / genetics
  • Lectins, C-Type / metabolism*
  • Lipopolysaccharides / immunology
  • Lipopolysaccharides / pharmacology
  • Macrophages / cytology
  • Macrophages / metabolism*
  • Macrophages / microbiology
  • Mannose Receptor
  • Mannose-Binding Lectins / genetics
  • Mannose-Binding Lectins / metabolism*
  • Models, Immunological
  • Mycobacterium tuberculosis / immunology*
  • Mycobacterium tuberculosis / physiology
  • NF-kappa B / metabolism
  • PPAR gamma / antagonists & inhibitors
  • PPAR gamma / genetics
  • PPAR gamma / metabolism*
  • Phospholipases A2, Cytosolic / metabolism
  • RNA Interference
  • Receptors, Cell Surface / genetics
  • Receptors, Cell Surface / metabolism*
  • Signal Transduction / drug effects
  • Signal Transduction / immunology
  • Tumor Necrosis Factor-alpha / metabolism
  • p38 Mitogen-Activated Protein Kinases / metabolism

Substances

  • 2-chloro-5-nitrobenzanilide
  • Anilides
  • Interleukin-8
  • Lectins, C-Type
  • Lipopolysaccharides
  • Mannose Receptor
  • Mannose-Binding Lectins
  • NF-kappa B
  • PPAR gamma
  • Receptors, Cell Surface
  • Tumor Necrosis Factor-alpha
  • lipoarabinomannan
  • Cyclooxygenase 2
  • p38 Mitogen-Activated Protein Kinases
  • Phospholipases A2, Cytosolic