At the same time, residual colonic innate immunity cells, such as neutrophils and macrophages, of WT + DSS mice regressed to WT control baseline levels ( Figure 2B). The adaptive immunity colonic mucosa cells, including Treg, however, did not fully regress (WT vs WT + DSS, P = .048; Figure 2B). This result,

which is in line with gross pathology observation of MLN enlargement at 7 months after DSS treatments, suggests that subtle alterations in local gut adaptive immunity networks may persist for a particularly Cabozantinib mouse long period after the restoration of colonic mucosa architecture and the regression of colitis. In an effort to explain why uPA−/− + DSS mice develop colonic polypoid adenomas in the long term, while WT + DSS ones do not, we next examined the colon of mice at the early time point of 1 week after DSS treatment. We found that WT and uPA−/−controls showed normal colon histology, whereas their DSS-treated counterparts had the typical DSS-associated ulcerative colitis. At this early time point, DSS-treated mice had numerous foci of epithelial dysplasia, characterized by the same histopathologic and immunohistochemical features as those described in polyps (Figure 3A). Colonic

dysplastic foci of uPA−/− + DSS mice, however, were in a more advanced stage of the dysplasia/preneoplasia sequence than those of WT + DSS mice (P = .0001; Figure 3, A and B). A total of 2-minute polyps were found in 2 uPA−/− + DSS mice (2 of 24) and 1-minute polyp was found in the WT + DSS mice (1 of 23). DSS-induced ulcerative lesions, located mostly at the last part of the descending colon and the rectum, consistently presented a larger surface epithelium deficit in the uPA−/− + IWR-1 concentration Adenosine triphosphate DSS mice compared to the same lesions

of the WT + DSS mice (P < .0001; Figure 3C). In the non-ulcerative parts of the gut mucosa, however, colitis in both groups of DSS-treated mice was characterized by comparable levels of inflammatory cell infiltration (P = .1098; Figure 3D). To examine whether the tumor-promoting uPA deficiency is associated with a different inflammatory cell composition of DSS colitis, we labeled in situ and then quantified selected critical inflammatory cell types in the colonic mucosa. We found that the numbers of MPO + neutrophils were significantly higher in both the ulcerative lesions (P = .0052; Figure 4A) and the remaining colonic mucosa (P = .0079; Figure W4A) of uPA−/− + DSS mice compared to topographically matching areas of WT + DSS mice. The presence of neutrophils was unremarkable in both uPA−/− and WT untreated controls ( Figure W4A). Likewise, F4/80 + macrophages were significantly more in the non-ulcerated colonic mucosa of the uPA−/− + DSS compared to the WT + DSS mice (P = .0011; Figure 4B). CD3 + lymphocytes, however, were less in the ulcerative lesions (P = .0039; Figure 4C) and in the colonic lamina propria (P = .0282; Figure W4B) of uPA−/− + DSS mice than those counted in the corresponding areas of WT + DSS mice.