Identification of genes involved in macrophage activation and effector functions against intracellular pathogens

 

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dc.contributor.advisor Brombacher, Frank en_ZA
dc.contributor.author Schwegmann, Anita Ruth en_ZA
dc.date.accessioned 2014-11-03T08:15:21Z
dc.date.available 2014-11-03T08:15:21Z
dc.date.issued 2006 en_ZA
dc.identifier.citation Schwegmann, A. 2006. Identification of genes involved in macrophage activation and effector functions against intracellular pathogens. University of Cape Town. en_ZA
dc.identifier.uri http://hdl.handle.net/11427/9031
dc.description Includes bibliographical references. en_ZA
dc.description.abstract This dissertation addressed the hypothesis that macrophages have an alternative killing mechanism that is independent of superoxide and nitric oxide but dependent on IFN-γ, TNF and C/EBPβ. Since the mechanism and the genes involved in this alternative pathway are mostly unknown, the aim of this dissertation was to identify these macrophage effector genes and to functionally characterize their role during infection utilizing gene deficient mouse models. Since mice deficient for C/EBPβ (C/EBPβ-/-) expressed normal levels of IFN-y and TNF during Listeria monocytogenes infection, the macrophage effector genes involved in confinement and killing of L. monocytogenes were postulated to be downstream of C/EBPβ. Furthermore, C/EBPβ-/- mice are highly susceptible L. monocytogenes due to impaired listericidal activity. Comparison of the gene expression profiles of WT and C/EBPβ-/- macrophages infected with L. monocytogenes was postulated to increase the probability of identifying these effector genes, which would be differentially expressed between the two groups. Comparative gene expression profiling by DNA microarrays between L. monocytogenes in infected WT and C/EBPβ-/- macrophages, successfully identified 1268 genes to be differentially expressed between the two groups. A focussed functional clustering strategy reduced the number of candidate genes to 220. PKCδ was selected for further study since it was involved in humoral defense, immune signalling, production of superoxide, regulation of transcription and may be putatively transcriptionally regulated by C/EBPβ. Furthermore, PKCδ was indirectly shown to promote L. monocytogenes escape from the phagosome and to negatively regulate transcription activity of C/EBPβ. In addition, since PKCδ was un-regulated, as shown by microarray and confirmed by RT-PCR, in L. monocytogenes infected C/EBPβ-/- macrophages, it was therefore thought to play a detrimental role during L. monocytogenes. However, since this premise has never been investigated directly, the role PKCδ during innate immunity against L monocytogenes was examined using the PKCδ deficient (PKCδ-/-) mouse model. Data in this dissertation provides new insight into the role of PKCδ during innate immunity to L. monocytogenes. PKCδ-/- mice were highly susceptible to L. monocytogenes due to enhanced listerial escape and impaired listericidal activity. Despite full macrophage activation and production of nitric oxide, PKCδ-/- mice displayed uncontrolled bacterial growth and dissemination of L. monocytogenes, which led to early death of the mice. In contrast, PKCδ-/- mice were able to control Mycobacterium infection as well as WT mice, suggesting that the activity of PKCδ may be negatively regulated by L. monocytogenes. A systems biology approach generated the hypothesis that PKCδ may promote Rab5a activation, which together with localized release of superoxide into the phagosome and activation of C/EBPβ by PKCδ, resulted in the confinement of the L. monocytogenes within the phagosome. Alternatively, PKCδ may act in a separate pathway that confines L monocytogenes within the phagosome, by activating and/or synergizing with unidentified proteins to neutralize that activity of listerial LLO and PI-PLC. Data in this dissertation clearly demonstrates that PKCδ is critical for confinement of L monocytogenes within phagosomes and may be part of a listericidal mechanism that is independent or nitric oxide, superoxide and pro-inflammatory cytokines. en_ZA
dc.language.iso eng en_ZA
dc.subject.other Biochemistry en_ZA
dc.title Identification of genes involved in macrophage activation and effector functions against intracellular pathogens en_ZA
dc.type Doctoral Thesis
uct.type.publication Research en_ZA
uct.type.resource Thesis en_ZA
dc.publisher.institution University of Cape Town
dc.publisher.faculty Faculty of Health Sciences en_ZA
dc.publisher.department Division of Immunology en_ZA
dc.type.qualificationlevel Doctoral
dc.type.qualificationname PhD en_ZA
uct.type.filetype Text
uct.type.filetype Image
dc.identifier.apacitation Schwegmann, A. R. (2006). <i>Identification of genes involved in macrophage activation and effector functions against intracellular pathogens</i>. (Thesis). University of Cape Town ,Faculty of Health Sciences ,Division of Immunology. Retrieved from http://hdl.handle.net/11427/9031 en_ZA
dc.identifier.chicagocitation Schwegmann, Anita Ruth. <i>"Identification of genes involved in macrophage activation and effector functions against intracellular pathogens."</i> Thesis., University of Cape Town ,Faculty of Health Sciences ,Division of Immunology, 2006. http://hdl.handle.net/11427/9031 en_ZA
dc.identifier.vancouvercitation Schwegmann AR. Identification of genes involved in macrophage activation and effector functions against intracellular pathogens. [Thesis]. University of Cape Town ,Faculty of Health Sciences ,Division of Immunology, 2006 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/9031 en_ZA
dc.identifier.ris TY - Thesis / Dissertation AU - Schwegmann, Anita Ruth AB - This dissertation addressed the hypothesis that macrophages have an alternative killing mechanism that is independent of superoxide and nitric oxide but dependent on IFN-γ, TNF and C/EBPβ. Since the mechanism and the genes involved in this alternative pathway are mostly unknown, the aim of this dissertation was to identify these macrophage effector genes and to functionally characterize their role during infection utilizing gene deficient mouse models. Since mice deficient for C/EBPβ (C/EBPβ-/-) expressed normal levels of IFN-y and TNF during Listeria monocytogenes infection, the macrophage effector genes involved in confinement and killing of L. monocytogenes were postulated to be downstream of C/EBPβ. Furthermore, C/EBPβ-/- mice are highly susceptible L. monocytogenes due to impaired listericidal activity. Comparison of the gene expression profiles of WT and C/EBPβ-/- macrophages infected with L. monocytogenes was postulated to increase the probability of identifying these effector genes, which would be differentially expressed between the two groups. Comparative gene expression profiling by DNA microarrays between L. monocytogenes in infected WT and C/EBPβ-/- macrophages, successfully identified 1268 genes to be differentially expressed between the two groups. A focussed functional clustering strategy reduced the number of candidate genes to 220. PKCδ was selected for further study since it was involved in humoral defense, immune signalling, production of superoxide, regulation of transcription and may be putatively transcriptionally regulated by C/EBPβ. Furthermore, PKCδ was indirectly shown to promote L. monocytogenes escape from the phagosome and to negatively regulate transcription activity of C/EBPβ. In addition, since PKCδ was un-regulated, as shown by microarray and confirmed by RT-PCR, in L. monocytogenes infected C/EBPβ-/- macrophages, it was therefore thought to play a detrimental role during L. monocytogenes. However, since this premise has never been investigated directly, the role PKCδ during innate immunity against L monocytogenes was examined using the PKCδ deficient (PKCδ-/-) mouse model. Data in this dissertation provides new insight into the role of PKCδ during innate immunity to L. monocytogenes. PKCδ-/- mice were highly susceptible to L. monocytogenes due to enhanced listerial escape and impaired listericidal activity. Despite full macrophage activation and production of nitric oxide, PKCδ-/- mice displayed uncontrolled bacterial growth and dissemination of L. monocytogenes, which led to early death of the mice. In contrast, PKCδ-/- mice were able to control Mycobacterium infection as well as WT mice, suggesting that the activity of PKCδ may be negatively regulated by L. monocytogenes. A systems biology approach generated the hypothesis that PKCδ may promote Rab5a activation, which together with localized release of superoxide into the phagosome and activation of C/EBPβ by PKCδ, resulted in the confinement of the L. monocytogenes within the phagosome. Alternatively, PKCδ may act in a separate pathway that confines L monocytogenes within the phagosome, by activating and/or synergizing with unidentified proteins to neutralize that activity of listerial LLO and PI-PLC. Data in this dissertation clearly demonstrates that PKCδ is critical for confinement of L monocytogenes within phagosomes and may be part of a listericidal mechanism that is independent or nitric oxide, superoxide and pro-inflammatory cytokines. DA - 2006 DB - OpenUCT DP - University of Cape Town LK - https://open.uct.ac.za PB - University of Cape Town PY - 2006 T1 - Identification of genes involved in macrophage activation and effector functions against intracellular pathogens TI - Identification of genes involved in macrophage activation and effector functions against intracellular pathogens UR - http://hdl.handle.net/11427/9031 ER - en_ZA


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