SHIP deficiency causes Crohn's disease-like ileitis

Kerr, William G; Park, Mi-Young; Maubert, Monique; Engelman, Robert W

The earliest manifestation of CD-like ileitis in SHIP-deficient mice, assigned grade 1, consisted of a mild (<25 PMN/hpf), predominantly PMN leucocyte infiltration of the lamina propria and frequently underlying lymph nodule (figure 1). The ileum of 9 of the 53 (17%) of the SHIP-deficient mice had grade 1 lesions. This mild, earliest lesion of the SHIP-deficient ileum had progressed in other individual SHIP À/À and SHIP DIP/DIP mice to a moderate (>25 PMN/hpf), mixed, but still predominantly PMN leucocyte infiltration of the expanded lamina propria and underlying lymph nodule, assigned grade 2, with attendant crypt regenerative hyperplasia manifest as IEC crowding, and elongation of crypt depth (figure 2). Grade 2 ileitis was present in 2 of the 53 (4%) of SHIP-deficient mice. Grade 3 inflammatory cell infiltrations were mixed and penetrated below the muscularis mucosa with distortion of villous architecture by the expanded mucosa and submucosa, and attendant crypt hyperplasia ( figure 3) . Five of the 53 (9%) of SHIP-deficient mice had grade 3 inflammatory lesions within the ileum.