SHIP deficiency causes Crohn's disease-like ileitis

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

To directly test whether SHIP-deficient haematolymphoid cells are responsible for the ileitis observed in SHIP-deficient strains, we adoptively transferred 5310 5 SHIP À/À splenocytes to each of six WT C57BL/6 hosts. The lungs and intestines were then analysed 1 month later for evidence of pathology. Segmental ileitis similar to that observed in germline SHIP-deficient mice was present in 5 of 6 WT mice that received SHIP À/À splenocytes with a mean ileitis score of 1.8 (the range of scores was 0e5). This analysis demonstrates that SHIP-deficiency of the haematolymphoid compartment is sufficient to alter enteric immune cell homeostatic responses in the small intestine resulting in a CD-like phenotype. Interestingly, adoptive transfer Figure 4 Grade 4 Crohn's disease-like ileitis of SHIP-deficient mice was comprised of a marked, mixed inflammatory cell infiltration of the ileum extending through the mucosa, submucosa, and into the tunica muscularis (A, B, C, F, G) . Such inflammatory cell infiltrations varied in composition, were in some areas of affected ileum predominantly polymorphonuclear (D), while in other areas were predominantly mononuclear with lymphocytes, histiocytes and numerous multi-nucleated giant cells present (B, E). Grade 4 ileitis was typically sharply delimited aggregates of pyo-granulomatous inflammatory cell infiltrations, at times in rosary-bead arrays (F, arrows), that caused thickening of the bowel wall (G, arrows) and lumen narrowing. Multinucleated giant cells (H), and pyo-granulomas (I) were frequently present in affected segments, but crypt abscesses (J, arrow) were less frequently observed. of FACS-purified CD3 + T cells, NK1.1 + CD3 À NK cells prepared from the spleens of SHIP À/À mice was unable to transfer any detectable ileitis to WT hosts (three hosts analysed per cell type). Thus, SHIP-deficient T cells or NK cells are sufficient for transfer of ileitis. We also observed that SHIP À/À splenocytes transfer a mild to moderate eosinophilic crystalline pneumonia to WT hosts with progression to patchy pulmonary consolidation in some cases as is observed in both germline SHIPdeficient mice 41 and MxCreSHIP flox/flox mice following gene ablation. 49 Neutrophilia combined with T cell paucity in the SHIP-deficient small intestine Our pathology findings and adoptive transfer studies described above suggest that a granulocyteemonocyte lineage cell may underlie the ileitis that we observe in SHIP-deficient mice. To further evaluate this possibility, we conducted multi-parametric cytometry assays of major immune cell populations including neutrophils, dendritic cells, CD4/CD8 T cells and Treg cells present in small intestines of SHIP-deficient and WT mice. In support of a role for neutrophils in ileitis, we find there is an absolute increase in total number of neutrophils present in the small intestine of SHIP À/À mice ( figure 10 ). This applied to neutrophils of the Ly6G + CD16/32 + phenotype as well as the CD62L + subset ( figure 10 A,B) . These findings of ileal neutrophilia are consistent with our histopathology studies described above. Surprisingly, we find a profound reduction in the number of both CD4 (figure 11A) and CD8 (figure 11B) T cells present in SHIP-deficient small intestines. When paired with the T cell adoptive transfer studies described above, these findings suggest that the CD-like ileitis observed in SHIP-deficient mice is not attributable to an autoimmune attack by SHIPdeficient T cells. Anal