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.
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Microbiol. Immunol. · Jan 2003
Purification, cloning and characterization of variant LukE-LukD with strong leukocidal activity of staphylococcal bi-component leukotoxin family.
Staphylococcus aureus produces bi-component leukotoxins composed of non-associated soluble proteins, S and F. Neither S nor F component alone is cytotoxic, but components together are active. These include Panton-Valentine leukocidin (PVL), gamma-hemolysin, LukE-LukD and others. ⋯ These activities were quite different from the LukE-LukD which was reported no hemolytic and poorly cytotoxic to leukocytes compared to PVL. The lukEv-IukDv was found in 87% of clinical isolates of Staphylococcus aureus but lukE-lukD was not detected. These data demonstrate the existence of variant LukE-LukD in V8 strain (ATCC 27733).
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Microbiol. Immunol. · Jan 2003
Comparative StudyComparison of a multiplex-PCR assay with mycolic acids analysis and conventional methods for the identification of mycobacteria.
A fast, sensitive and cost-effective multiplex-PCR assay for Mycobacterium tuberculosis complex (MTC) and Mycobacterium avium (M. avium) identification for routine diagnosis was evaluated. A total of 158 isolates of mycobacteria from 448 clinical specimens from patients with symptoms of mycobacterial disease were analyzed. By conventional biochemical methods 151 isolates were identified as M. tuberculosis, five as M. avium and two as Mycobacterium chelonae (M. chelonae). ⋯ The method applied to isolates from two patients, identified by conventional methods and mycolic acid analysis, one as M. avium and other as M. chelonae, resulted positive for IS6110, suggesting co-infection with M. tuberculosis. These patients were successfully submitted to tuberculosis treatment. The multiplex-PCR method may offer expeditious identification of MTC and M. avium, which may minimize risks for active transmission of these organisms and provide useful treatment information.
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Microbiol. Immunol. · Jan 2002
Differential expression and polarized secretion of CXC and CC chemokines by human intestinal epithelial cancer cell lines in response to Clostridium difficile toxin A.
Intestinal epithelial cells are the initial sites of host response to Clostridium difficile infection and can play a role in signaling the influx of inflammatory cells. To further explore this role, the regulated expression and polarized secretion of CXC and CC chemokines by human intestinal epithelial cells were investigated. An expression of the CXC chemokines, including IL-8 and growth-related oncogene (GRO)-alpha, and the CC chemokine monocyte chemoattractant protein (MCP)-1 from HT-29 cells increased in the 1-6 hr following C. difficile toxin A stimulation, assessed by quantitative RT-PCR. ⋯ Moreover, the addition of IFN-gamma and TNF-alpha to toxin A stimulated Caco-2 cells increased the basolateral release of CC chemokine MCP-1. In contrast, IFN-gamma and TNF-alpha had no effect on the expression of the CXC chemokines IL-8 and GRO-alpha. These results suggest that a CXC and CC chemokine expression from epithelial cells infected with C. difficile may be an important factor in the mucosal inflammatory response.
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Microbiol. Immunol. · Jan 2001
Role of interleukin (IL)-1 type 1 receptor in mycobacterial infection.
It is important to gain a better understanding of IL-1-mediated signaling events in mycobacterial infection. In order to clarify the role of IL-1 receptor type 1 (IL-1 R1) in IL-1 R1, knockout (KO) mice were infected with either Mycobacterium tuberculosis H37Rv or Kurono strain by the respiratory route, and their ability to control mycobacterial growth, pulmonary granuloma formation, and cytokine mRNA expression was investigated. ⋯ Interferon-y production by spleen cells was low in IL-1 R1 KO mice. It is concluded that the IL-1 R1 is essential for IL-1-mediated signaling events in mycobacterial infection.