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Keywords:

  • Mycobacterium tuberculosis ;
  • apoptosis;
  • macrophage;
  • clinical isolates;
  • multidrug resistance

Abstract

Some multidrug-resistant (MDR) Mycobacterium tuberculosis (Mtb) genotypes are the cause of large outbreaks, including strain M identified in Argentina. In contrast, its kin strain 410 has only caused a single case to date. Cell wall antigens from Mtb were associated with the modulation of macrophage (MΦ) cell death, and the ability to inhibit of MΦ apoptosis is considered a virulence mechanism. In this study, the ability these two clinical isolates with divergent epidemiology to induce MΦ cell death was evaluated using whole inactivated bacteria. We showed that gamma-irradiated (I-) strains induced MΦ necrosis, the strongest inducer being I-410. Cell death biased towards apoptosis with the heat-killed (hk) strains, both hk-MDR strains being poorer inducers of MΦ apoptosis than was H37Rv. These effects were partly due to their ability to induce anti-apoptotic mechanisms which were not related to the lack of tumor necrosis factor alpha induction or a compensatory effect of interleukin-10. The most noticeable difference between strain M and strain 410 was the ability shown by hk-M to interfere with apoptosis induced by hk-H37Rv. Thus, heat-stable and heat-labile antigens from these epidemiologically divergent Mtb strains differ in their ability to manipulate MΦ death.