Expression and function of transforming growth factor β in melioidosis

Infect Immun. 2012 May;80(5):1853-7. doi: 10.1128/IAI.05534-11. Epub 2012 Feb 13.

Abstract

Melioidosis, caused by the Gram-negative bacterium Burkholderia pseudomallei, is an important cause of community-acquired sepsis in Southeast Asia and northern Australia. An important controller of the immune system is the pleiotropic cytokine transforming growth factor β (TGF-β), of which Smad2 and Smad3 are the major signal transducers. In this study, we aimed to characterize TGF-β expression and function in experimental melioidosis. TGF-β expression was determined in 33 patients with culture-proven infection with B. pseudomallei and 30 healthy controls. We found that plasma TGF-β concentrations were strongly elevated during melioidosis. In line with this finding, TGF-β expression in C57BL/6 mice intranasally inoculated with B. pseudomallei was enhanced as well. To assess the role of TGF-β, we inhibited TGF-β using a selective murine TGF-β antibody. Treatment of mice with anti-TGF-β antibody resulted in decreased lung Smad2 phosphorylation. TGF-β blockade appeared to be protective: mice treated with anti-TGF-β antibody and subsequently infected with B. pseudomallei showed diminished bacterial loads. Moreover, less distant organ injury was observed in anti-TGF-β treated mice as shown by reduced blood urea nitrogen (BUN) and aspartate transaminase (AST) values. However, anti-TGF-β treatment did not have an effect on survival. In conclusion, TGF-β is upregulated during B. pseudomallei infection and plays a limited but proinflammatory role during experimental melioidosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Gene Expression Regulation / physiology*
  • Humans
  • Inflammation / metabolism
  • Lung / metabolism
  • Male
  • Melioidosis / metabolism*
  • Mice
  • Mice, Inbred C57BL
  • Phosphorylation
  • Sepsis
  • Signal Transduction
  • Smad2 Protein / genetics
  • Smad2 Protein / metabolism
  • Transforming Growth Factor beta / genetics
  • Transforming Growth Factor beta / metabolism*

Substances

  • Smad2 Protein
  • Smad2 protein, mouse
  • Transforming Growth Factor beta