GI22 - Intestinal S100/Calgranulin Expression in Cats with Chronic Enteropathies

Abstract: Background: Diagnosis of chronic inflammatory enteropathies (CIE) in cats and differentiation from intestinal lymphoma using currently available diagnostics is challenging. The S100/calgranulins appear as useful non-invasive biomarkers for canine CIE, with increased intestinal expression, but have not been evaluated in cats.

Hypothesis: We hypothesized that the S100/calgranulins are differentially expressed between feline CIE and intestinal lymphoma, and correlate with histological and/or clinical disease severity.

Animals: Retrospective case-control study including patient data and gastrointestinal tissue from 16 cats with CIE and 8 with intestinal lymphoma.

Methods: Gastrointestinal tissue biopsies were immunohistochemically stained using species-specific polyclonal α-S100A8/A9 and α-S100A12 antibodies. Epithelial and lamina propria S100A8/A9⁺ and S100A12⁺ cells per 10,000 µm² were compared between groups of cats and tested for a correlation with clinicopathologic abnormalities, clinical disease severity (feline chronic enteropathy activity index [FCEAI] score), and histologic lesions.

Results: S100A8/A9⁺ and S100A12⁺ cells were detected in all gastrointestinal segments, without significant differences between CIE and lymphoma. Segmental inflammatory lesions were moderately to strongly correlated with increased S100/calgranulin-positive cell counts. Increased ileal S100A12⁺ cell counts correlated with hypocobalaminemia (P = 0.0229). Hypofolatemia was linked to higher duodenal S100A8/A9⁺ cell counts. FCEAI scores were higher in cats with lymphoma than CIE (P = 0.0101) and were linked to higher duodenal S100A12⁺ cell counts (P = 0.0385).

Conclusions and clinical importance: These findings suggest a role of the S100/calgranulins in the pathogenesis of the spectrum of feline chronic enteropathies and emphasize the diagnostic value of B vitamin determination and clinical disease grading.