Dextran sodium sulphate‐induced colitis activity varies with mouse strain but develops in lipopolysaccharide‐unresponsive mice

Bacteria and their products have been implicated in the pathogenesis of chronic Inflammatory Bowel disease. The aim of this study was to investigate the potential role of lipopolysaccharides (LPS) in the development of intestinal injury by comparing the effects of the dextran sodium sulphate (DSS)-induced model of colitis in LPS-sensitive and -insensitive mice. Experimental colitis was induced in LPS-sensitive mice (C3H/He) and their LPS-insensitive congenic strain (C3H/HeJ). Colitis was assessed clinically using a disease activity index (derived from the three main clinical signs; diarrhoea, rectal bleeding and weight loss) and by histological scoring of the diseased colon. The clinical signs and disease activity index did not differ between the LPS-sensitive and -insensitive costrains. Similarly, histological scores did not differ significantly for either C3H strain at any time point during exposure to DSS. However, there were differences in the inflammatory response when different strains were compared (C3H vs CBA): the effects of DSS in C3H mice were immediate, more severe and mainly involved the caecum and ascending colon. These findings suggest that LPS from colonic bacteria do not play a primary role in the initiation of DSS-induced colitis and demonstrate clear differences in the responsiveness of different mouse strains to DSS.