Molecular structure of the Mycobacterium tuberculosis virulence factor, mycolic acid, determines the elicited inflammatory pattern


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Vander Beken S., Al Dulayymi J. R. , Naessens T., Koza G. , Maza-Iglesias M., Rowles R., ...More

EUROPEAN JOURNAL OF IMMUNOLOGY, vol.41, pp.450-460, 2011 (Journal Indexed in SCI) identifier identifier identifier

  • Publication Type: Article / Article
  • Volume: 41
  • Publication Date: 2011
  • Doi Number: 10.1002/eji.201040719
  • Title of Journal : EUROPEAN JOURNAL OF IMMUNOLOGY
  • Page Numbers: pp.450-460
  • Keywords: Alveolar macrophage, Mycolic acid, Mycobacterium tuberculosis, Pulmonary inflammation, NECROSIS-FACTOR-ALPHA, CELL-ENVELOPE LIPIDS, SINGLE ENANTIOMERS, CORD FACTOR, TREHALOSE 6,6'-DIMYCOLATE, PULMONARY TUBERCULOSIS, KETOMYCOLIC ACIDS, TUBERCLE-BACILLI, FATTY-ACIDS, WALL

Abstract

Mycolic acids (MAs) occur in the cell wall of Mycobacterium tuberculosis as variable mixtures of different classes and chain lengths. Here, we address the relationship between the structure and its inflammatory function of this virulence factor using single synthetic MA isomers, differing in oxygenation class and cis-versus alpha-methyl-trans proximal cyclopropane orientation. Analysis of bronchoalveolar inflammation, lung histopathology and alveolar macrophage transcription revealed a strong dependence on these meromycolic chemistries of mouse pulmonary inflammation in response to intratracheal treatments with MAs. Whereas alpha-MA was inert, oxygenated methoxy- and keto-MA with cis-cyclopropane stereochemistry elicited solid to mild inflammatory responses respectively. In trans-cyclopropane orientation, methoxy-MA partially lost its inflammatory activity and keto-MA exerted anti-inflammatory alternative activation of alveolar macrophages and counteracted cis-methoxy-MA induced airway inflammation. The differential innate immune activities of MAs demonstrated here, dependent on oxygenation class and cis versus alpha-methyl-trans cyclopropane chemistry, identify a novel means for M. tuberculosis to steer host immune responses during infection.