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087 A POTENTIAL ROLE FOR FUSOBACTERIUM NUCLEATUM IN THE AETIOLOGY OF INFLAMMATORY BOWEL DISEASES J Strauss, C Ambrose, S Ness, K Rioux, P Beck, R DeVinney, E Allen-Vercoe Fusobacterium nucleatum is a Gram-negative, spindle-shaped, anaerobic bacterium that is normally found in high numbers in the oral cavity, where it is occasionally associated with oral inflammatory disorders. F. nucleatum is known to invade buccal epithelial cells and to elicit the secretion of the pro-inflammatory chemokine interleukin-8 (IL-8). Interestingly, the virulence of different oral isolates of F. nucleatum has been found to be highly variable. From previous studies of organisms culturable from human feces, F. nucleatum is considered an occasional resident of the intestinal tract. However, any potential role for this microorganism in inflammatory disorders of the lower intestinal tract has remained largely unexplored.
Gastrointestinal Research Group, Faculty of Medicine, University of Calgary, Calgary, Alberta
Using immunofluorescence microscopy together with polyclonal antisera raised against F. nucleatum outer membrane proteins, we have shown that the F. nucleatum type strain ATCC 25586 is able to invade the human intestinal cell-lines, Caco-2 and T84. Various metabolic inhibitors applied during infections of Caco-2 cells were used in order to elucidate the mechanism of invasion. Additionally, with a T84 cell model, we used a capture ELISA to show that this F. nucleatum type strain is able to elicit the secretion of IL-8.
Using highly selective media and strict anaerobic growth conditions, we next examined whether F. nucleatum could be isolated from gut mucosal biopsies obtained during colonoscopy. To date, we have recovered several different isolates from both healthy individuals (undergoing colon cancer screens), and patients suffering from colitis. We used our tissue culture models of infection as above to determine the extent that these bacteria invade and elicit a pro-inflammatory response. Our preliminary data suggests that these gut isolates are highly heterologous, and some have the potential to cause inflammatory disease in the human host.