Neurtophil-macrophage interactions in the early response against infection : a dissertation /
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| Format: | Thesis Book |
| Language: | English |
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College Station, Tex. :
Texas A&M University System Health Science Center,
2007.
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| Subjects: |
| Abstract: | ABSTRACT: Both alveolar macrophages (AM) and neutrophils are present early at the site of mycobacterial infection and can produce cytokines and chemokines on interaction with M. tuberculosis. The interactions between these two cell types may be crucial for the initiation of both innate and adaptive immune responses. Using a guinea pig model, we have investigated the role of these inflammatory cells, either alone or in co-cultures, in the early immune response against M. tuberculosis infection. Neutrophils and AM were isolated from naive guinea pigs, cultured together or alone, and infected with virulent M. tuberculosis. IL-8 protein production in co-cultures, as measured by ELISA, was found to be additive and significantly greater in M. tuberculosis-infected co-cultures as compared to uninfected co-cultures and infected neutrophils or macrophages alone. Using a Transwell insert culture system, contact-independent cell cultures were studied in which neutrophils were infected with virulent M. tuberculosis in the upper well, and AM were cultured in the lower well. Relaese of hydrogen peroxide from AM exposed to soluble products from infected neutrophils was significantly increased compared to soluble products from infected neutrophils was significantly increased compared to unexposed AM. Significant up-regulation of IL-1 [beta] and TNF-[alpha] mRNA levels was also observed in AM, as compared to cells not exposed to soluble neutrophil products. Treatment with anti-gpTNF[alspha] polyclonal antibody completely abrogated the response of AM to neutrophil products. Therefore, we examined the ability of guinea pig recombinant IL-8 (CXCL8) to activate neutrophils. Guinea pig neutrophils were activated with rgpIL-8 and infected with virulent M. tuberculosis. IL-8 and TNF-[apha] mRNA levels and protein levels were found to be significantly elevated for rgpIL-8 treated, infected neutrophils. In the Transwell insert culture system. the release of hydrogen peroxide from AM exposed to the supenatants from the rgpIL-8 treated, infected neutrophils was found to be significantly increased. IL-[beta] and TNF-[alpha] mRNA expression was also found to be significantly up-regulated in AM exposed to rgp-IL-8 treated, infected neutrophils in non-contact co-cultures, as was the control of intracellular growth of M. tuberculosis in exposed AM. Neutralizing anti-rgpTNF[alpha] polyclonal antibody abrogated the response of AM to the supernatants from the rgpIL-8 treated, infected neutrophils may be playing an important role in the activation of AM. Significant induction of apoptosis in M. tuberculosis-infected neutrophils was observed as compared to the uninfected neutrophils. These apoptotic neutrophils contained intracellular, viable mycobacteria as demonstrated by gentamicin protection assay. M. tuberculosis-infected, apoptotic neutrophils were also phagocytosed by AM as seen by the presence of the myeloperoidase-stained apoptotic bodies in AM. Feeding of infected, apoptotic neutrophils to AM induced a significant up-regulation of TNF-[alpha] and IL-1[beta] mRNA compared to AM exposed to staurosporine-treated apoptotic neutrophils. Enhanced intracellular mycobacterial growth was also seen in AM fed with infected, apoptotic neutrophils as compared to the AM infected with M. tuberculosis H37Rv alone. Taken together, these data suggest that neutrophil-macrophage interactions may contribute to host defense M. tuberculosis infection. |
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| Item Description: | Vita. "Major Subject: Medical Sciences". "Submitted to the Graduate School of Biomedical Sciences of the Texas A&M University System Health Science Center in partial fulfillment of the requirements for the degree of Doctor of Philosophy May 2007." Approved as to style and content by: David N. McMurray, Vernon L. Tesh, James E. Samuel, Jane Welsh, John Quarles. |
| Physical Description: | xi, 93 leaves : illustrations ; 28 cm. |
| Bibliography: | Includes bibliographical references (leaves 85-93). |