Fig. 2.

MMP-2^−/−/MMP-9^−/− dKO mice are resistant to DSS-induced colitis. WT C57/B6 and MMP-2^−/−/MMP-9^−/− dKO mice, 8 wk old, were weighed and given water or DSS (3% wt/vol) for 7 days. Mice were euthanized, and colon was processed for histology. A: disease severity was assessed and expressed in terms of clinical activity score. Clinical score was calculated by using parameters of stool consistency, weight loss, and fecal blood. Each bar represents means ± SE, *P < 0.05. B: mean histological score of MMP-2^−/−/MMP-9^−/− dKO mice compared with WT. Each bar represents means ± SE, *P < 0.05. C: representative sections from 2 individual experiments. N = 6 for DSS group with magnifications ×4, ×10, and ×40. Colon specimens from descending colon were fixed in formalin, and histological score was calculated on hematoxylin and eosin (H&E) sections based on 3 variables: inflammatory cells, crypt damage, and ulcers. Colons were snap frozen in liquid nitrogen, and myeloperoxidase (MPO) activity was measured (D) as an index of neutrophil infiltration into the injured tissue. Each bar represents means ± SE; n = 6 animals for each group. *P < 0.05. E: mice were given water or 3% DSS (wt/vol) for 7 days, after which time mice were euthanized. After 24 h, supernatants were collected from colonic organ culture and were centrifuged, and interleukin (IL)-6 and keratinocyte-derived chemokine (KC) levels were measured by ELISA. Each bar represents mean ± SE, *P < 0.05 and n = 6 for each group.