CEACAM1 and inflammatory bowel disease: In contrast, our recently identified mAIEC27 was effective in invading mouse macrophages since it binds to and enters host cells by using CEACAM1, which is highly expressed in mouse enterocytes and intestinal macrophages.51 Thus, this novel mAIEC strain might represent a more appropriate strain for studying the effect of AIEC colonisation in mouse models of IBD.