Comparative analysis of c-kit gene expression and c-Kit immunoreactivity in horses with and without obstructive intestinal disease

Previous immunohistochemical studies targeting the receptor tyrosine kinase (c-Kit) have demonstrated an apparent reduction in the number of gastrointestinal pacemaker cells--the interstitial cells of Cajal (ICC)--in horses with intestinal motility disorders. This study compared the level of transcription of the c-kit gene encoding this receptor in horses with and without such motility disorders. Transcription levels of this gene were also compared to the density of ICC immunohistochemically positive for the c-Kit antigen. Intestinal samples were collected from 18 horses with intestinal disease and from 15 control animals. Following gene extraction and identification, real-time quantitative analysis of c-kit and a control gene, ACTB (β-actin), was carried out on all samples and the density of the c-Kit-positive ICC compared. There was a significant reduction in c-Kit immunoreactivity in the ICC of horses with large intestinal obstructive disorders relative to controls but no significant difference in the transcription of the c-kit gene between normal and affected animals. Further studies will be required to elucidate the mechanisms regulating c-Kit expression and to assess the pathophysiological significance of these findings

Characterisation of the inflammatory reaction in equine idopathic focal eosinophilic enteritis and diffuse eosinophilic enteritis

REASONS FOR PERFORMING STUDY: Idiopathic focal eosinophilic enteritis (IFEE) and diffuse eosinophilic enteritis (DEE) are primary eosinophilic intestinal conditions without a known cause that are associated with an increasing number of surgical colic cases. Histology may be helpful in defining disease aetiology and pathogenesis. OBJECTIVES: To characterise further the inflammatory infiltrate in equine IFEE and to compare the condition with DEE. METHODS: Twenty-three IFEE cases and 5 DEE cases were examined by light microscopy including immunohistology to identify infiltrating leucocytes. Inflammatory infiltrates in mucosa and submucosa were characterised in IFEE lesions (Group 1), the intestine distant from the lesions in IFEE (Group 2) and DEE (Group 3). RESULTS AND CONCLUSIONS: IFEE lesions represented an accumulation of leucocytes in submucosa and muscularis, with dominance of eosinophils and macrophages and smaller numbers of lymphocytes, plasma cells and neutrophils. T cells represented the dominant lymphocytes. The mucosa overlying the lesion and both mucosa and submucosa in IFEE nonlesion sites and in DEE exhibited a similar composition, with different prevalence of various cell types. Macrophages were significantly more prevalent in the mucosal and submucosal infiltrates in IFEE nonlesion sites than in DEE, and lymphocytes significantly more prevalent in the mucosa in DEE than in IFEE nonlesion sites. The findings confirm IFEE as a primary eosinophilic intestinal disorder and indicate that IFEE represents a focally exacerbated inflammatory reaction in horses with DEE, possibly due to functional changes in the macrophage and T cell components, with subsequent excessive recruitment of both eosinophils and macrophages