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INFLAMMATION/IMMUNITY/MEDIATORS
1Intestinal Diseases Research Programme, McMaster University, Hamilton, Ontario, Canada; 2Department of Surgical and Gastroenterological Sciences, Padua University, Padua, Italy; 3Department of Medicine, William Osler Health Centre, Brampton, Etobicoke, Ontario, Canada; 4Department of Pathology, University of Michigan, Ann Arbor, Michigan; and 5Division of Gastroenterology, British Columbia's Children's Hospital, Vancouver, British Columbia, Canada
Submitted 3 October 2007 ; accepted in final form 16 January 2008
Although macrophages are considered a critical factor in determining the severity of acute inflammatory responses in the gut, recent evidence has indicated that macrophages may also play a counterinflammatory role. In this study, we examined the role of a macrophage subset in two models of colitis. Macrophage colony-stimulating factor (M-CSF)-deficient osteopetrotic mice (op/op) and M-CSF-expressing heterozygote (+/?) mice were studied following the induction of colitis by either dinitrobenzene sulfonic acid (DNBS) or dextran sulfate sodium (DSS). DNBS induced a severe colitis in M-CSF-deficient op/op mice compared with +/? mice. This was associated with increased mortality and more severe macroscopic and microscopic injury. Colonic tissue myeloperoxidase (MPO) activity as well as concentrations of TNF-
, IL-1β, and IL-6 were higher and IL-10 lower in op/op mice with DNBS colitis. The severity of inflammation and mortality was attenuated in op/op mice that had received human recombinant M-CSF prior to the induction of colitis. In contrast, op/op mice appeared less vulnerable to colitis induced by DSS. Macroscopic damage, microscopic injury, MPO activity, and tissue concentrations of TNF-
, IL-1β, and IL-6 were all lower in op/op mice compared with +/? mice with DSS colitis, and no changes were seen in IL-10. Macrophage inflammatory protein-1
concentrations were increased in op/op but not +/? mice following colitis induced by DNBS but not DSS. These results indicate that M-CSF-dependent macrophages may play either a pro- or counterinflammatory role in acute experimental colitis, depending on the stimulus used to induce colitis.
macrophages; macrophage colony-stimulating factor; experimental colitis; cytokines; inflammatory bowel disease
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