SHIP deficiency causes Crohn's disease-like ileitis

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

Necropsies were performed in a systematic, comprehensive manner. The entire alimentary tract, including the oesophagus, stomach, duodenum, jejunum, ileum, caecum, and colon and associated mesentery and mesenteric lymph nodes was evaluated, and the alimentary tract was insufflated with 10% neutralbuffered formalin and rolled in segments to fit as Swiss rolls into cassettes for histological processing and microscopic evaluation. The skin, subcutis, skeletal muscle, inguinal lymph node and mammary fat pad, cervical lymph node, salivary glands, reproductive tract and associated glands, liver, gall bladder, spleen, pancreas, kidneys and adrenal glands, were evaluated. The larynx, trachea with attached thyroid and parathyroid glands, heart, thymus, and lungs insufflated with 10% neutral-buffered formalin were collected. Tissues were fixed in 10% neutralbuffered formalin, dehydrated, embedded in paraffin, sectioned at 3 mm and stained with H&E. Histological sections of each segment of the alimentary tract were masked, assessed and assigned an inflammatory grade of 0e6, with grade 6 representing the most progressed, severe lesion. Inflammatory grades assigned were as follows: inflammatory grade 0¼no significant abnormalities; inflammatory grade 1¼mild predominantly polymorphonuclear (PMN) leucocyte infiltrations (<25 PMN/ hpf) of the lamina propria and/or enteric lymph nodule; inflammatory grade 2¼moderate predominantly PMN leucocyte infiltrations (>25 cells/hpf) of the lamina propria and/or lymph nodule; inflammatory grade 3¼marked inflammatory cell infiltrations with extension below the muscularis mucosa causing architectural distortion of the mucosa and submucosa with attendant crypt hyperplasia; inflammatory grade 4¼marked infiltrations with extension into the tunica muscularis; inflammatory grade 5¼marked transmural leucocyte infiltrations; inflammatory grade 6¼marked transmural leucocyte infiltrations with extension into the mesentery and/or other organs. In each section the presence of granuloma, crypt abscess, stricture, fissure, and whether dissemination of inflammation to other sites had occurred was noted. Inflammatory scores were compared between cohorts by one-way ANOVA. All reported p-values are two-sided with p<0.01 considered significant. The sections were scored by a single, board certified veterinary pathologist. The sections were scored by a veterinary pathologist with confirmation of scoring system and subsequent gradations by a clinical pathologist.