Microbiology and immunology
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Microbiol. Immunol. · Jan 2005
Survival of virulent Mycobacterium tuberculosis involves preventing apoptosis induced by Bcl-2 upregulation and release resulting from necrosis in J774 macrophages.
Macrophage apoptosis plays a role in mycobacterial infection. To define the mechanism by which virulent Mycobacterium tuberculosis escapes apoptosis and killing in macrophages, J774 macrophages were infected with virulent M. tuberculosis H37Rv and attenuated H37Ra strains. ⋯ Fas mRNA expression was downregulated and FasL was upregulated in H37Ra- and H37Rv-infected macrophages, while Bcl-2 was upregulated in H37Rv-infected macrophages but downregulated in H37Ra-infected macrophages as seen by real-time PCR. These results indicate that M. tuberculosis H37Ra and H37Rv proliferate in macrophages by preventing them from inducing apoptosis during the early phase of infection, and that M. tuberculosis H37Rv-infected macrophages are found to express Bcl-2 mRNA, which leads to anti-apoptotic activity, and that relatively distinct necrosis might occur during the later phase of infection.