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12 results on '"Flynn, Andrew N."'

3. Apoptosis-inducing factor contributes to epithelial cell apoptosis induced by enteropathogenic Escherichia coli

Author

Flynn, Andrew N., Wang, Arthur, McKay, Derek M., and Buret, Andre G.

Subjects
Epithelium -- Physiological aspects, Apoptosis -- Research, Epithelial cells -- Physiological aspects, Escherichia coli -- Health aspects, Biological sciences
Abstract

The mechanisms by which enteropathogenic Escherichia coli (EPEC) causes intestinal epithelial cell apoptosis remain unclear. We tested the hypothesis that apoptosis-inducing factor (AIF) is involved in apoptosis induced by EPEC. Infection of intestinal epithelial cells in vitro with EPEC led to the mitochondrial and cytosolic accumulation of AIF. This effect was partially dependent on caspase activity. Knockdown of AIF with siRNA blocked cellular apoptosis in response to EPEC infection, as assessed by poly(ADP-ribose) polymerase cleavage and oligonucleosome formation. Taken together, these data suggest that caspase-dependent mobilization of AIF contributes to EPEC-induced epithelial cell apoptosis. Key words: enteropathogenic Escherichia coli, apoptosis-inducing factor, intestinal epithelium, apoptosis. Les mecanismes par lesquels les Escherichia coli enteropathogenes (EPEC) provoquent l'apoptose des cellules epitheliales intestinales demeurent obscurs. Nous avons verifie l'hypothese que le facteur inducteur de l'apoptose (AIF) est implique dans l'apoptose induite par les EPEC. L'infection des cellules epitheliales intestinales in vitro au moyen d'EPEC a conduit a l'accumulation mitochondriale et cytosolique de l'AIF. Cet effet a ete partiellement dependant de l'activite des caspases. L'elimination de l'AIF par siRNA a bloque l'apoptose cellulaire en reeponse a l'infection, tel qu'evalue par le clivage de la poly(ADP-ribose) polymerase et la formation d'oligonucleiosomes. Ces resultats laissent supposer que la mobilisation de l'AIF deependante des caspases contribue a l'apoptose des cellules eepitheliale induite par les EPEC. Mots-cles : Escherichia coli enteropathogenes, facteur inducteur de l'apotose, epithelium intestinal, apoptose. [Traduit par la Redaction], Introduction Enteropathogenic Escherichia coli (EPEC) is a major cause of infant diarrhea in developing countries, and causes significant levels of mortality (Nataro and Kaper 1998). This pathogen tightly adheres to [...]

Published
2011
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4. The role of caspase-3 in lipopolysaccharide-mediated disruption of intestinal epithelial tight junctions

Author

Chin, Alex C., Flynn, Andrew N., Fedwick, Jason P., and Buret, Andre G.

Subjects
Lipids -- Complications and side effects -- Health aspects, Cysteine proteinases -- Properties -- Health aspects, Cell junctions -- Abnormalities -- Health aspects, Intestines -- Diseases -- Health aspects, Microbial polysaccharides -- Complications and side effects -- Health aspects, Apoptosis -- Causes of -- Health aspects, Junctional complexes (Epithelium) -- Abnormalities -- Health aspects, Biological sciences, Diseases, Complications and side effects, Properties, Abnormalities, Health aspects, Causes of
Abstract

Abstract: The mechanisms responsible for microbially induced epithelial apoptosis and increased intestinal permeability remain unclear. This study assessed whether purified bacterial lipopolysaccharide (LPS) increases epithelial apoptosis and permeability and whether [...]

Published
2006

5. Crohn's Disease Exacerbation Induced by Edwardsiella tarda Gastroenteritis

Author

Arya, Aman V., Rostom, Alaa, Dong, Wei-Feng, and Flynn, Andrew N.

Subjects
Published: October 2011, Crohn's disease, Edwardsiella tarda, Bacterial gastroenteritis
Abstract

Exacerbations of Crohn's disease are not infrequently associated with bacterial gastroenteritis. The recognition of synchronous infections in such patients is vital for the initiation of appropriate antimicrobial therapy. Furthermore, the detection of active bacterial infections may lead the clinician to delay starting biological therapy. We report here a man presenting with an exacerbation of his Crohn's disease during a trip to Thailand. Stool cultures were positive for the unusual gut pathogen Edwardsiella tarda. The patient's symptoms resolved with concurrent antibiotic and steroid therapy. This finding demonstrates the value of performing stool culture in all patients presenting with exacerbations of inflammatory bowel diseases.

Published
2011

6. Host Epithelial Interactions with Helicobacter Pylori: A Role for Disrupted Gastric Barrier Function in the Clinical Outcome of Infection?

Author

Buret, Andre G, Fedwick, Jason P, and Flynn, Andrew N

Subjects
Article Subject
Abstract

Infection of the human stomach with Helicobacter pylori may develop into gastritis, ulceration, adenocarcinoma and mucosal lymphomas. The pathogenic mechanisms that determine the clinical outcome from this microbial-epithelial interaction remain poorly understood. An increasing number of reports suggests that disruptions of epithelial barrier function may contribute to pathology and postinfectious complications in a variety of gastrointestinal infections. The aim of this review is to critically discuss the implications of H pylori persistence on gastric disease, with emphasis on the role of myosin light chain kinase, claudins and matrix metalloproteinases in gastric permeability defects, and their contribution to the development of cancer. These mechanisms and the associated signalling events may represent novel therapeutic targets to control disease processes induced by H pylori, a microbial pathogen that colonizes the stomach of over 50% of the human population.

Published
2005
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12. Tilmicosin-induced bovine neutrophil apoptosis is cell-specific and downregulates spontaneous LTB4 synthesis without increasing Fas expression

Author

Lee, Wilson D., Flynn, Andrew N., LeBlanc, Justin M., Merrill, John K., Dick, Paul, Morck, Douglas W., and Buret, Andre G.

Abstract

The pathology of bacterial pneumonia, such as seen in the bovine lung infected with Mannheimia haemolytica, is due to pathogen virulence factors and to inflammation initiated by the host. Tilmicosin is a macrolide effective in treating bacterial pneumonia and recent findings suggest that this antibiotic may provide anti-inflammatory benefits by inducing polymorphonuclear neutrophilic leukocyte (PMN) apoptosis. Using an in vitro bovine system, we examined the cell-specificity of tilmicosin, characterized the changes in spontaneous leukotriene B4 (LTB4) synthesis by PMN exposed to the macrolide, and assessed its effects on PMN Fas expression. Previous findings demonstrated that tilmicosin is able to induce PMN apoptosis. These results were confirmed in this study by the Annexin-V staining of externalized phosphatidylserine and the analysis with flow cytometry. The cell-specificity of tilmicosin was assessed by quantification of apoptosis in bovine PMN, mononuclear leukocytes, monocyte-derived macrophages, endothelial cells, epithelial cells, and fibroblasts cultured with the macrolide. The effect of tilmicosin on spontaneous LTB4 production by PMN was evaluated via an enzyme-linked immunosorbent assay. Finally, the mechanisms of tilmicosin-induced PMN apoptosis were examined by assessing the effects of tilmicosin on surface Fas expression on PMN. Tilmicosin-induced apoptosis was found to be at least partially cell-specific, as PMN were the only cell type tested to die via apoptosis in response to incubation with tilmicosin. PMN incubated with tilmicosin under conditions that induce apoptosis spontaneously produced less LTB4, but did not exhibit altered Fas expression. In conclusion, tilmicosin-induced apoptosis is specific to PMN, inhibits spontaneous LTB4 production, and occurs through a pathway independent of Fas upregulation.

Published
2004

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