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ROLE OF Fer KINASE IN INTESTINAL MODELS OF INFLAMMATION

M Khajah, R Zhang, DM McCafferty
Gastrointestinal Research Group, University of Calgary, Calgary, Alberta

BACKGROUND: Fer kinase is a member of group IV family of non-receptor protein tyrosine kinase (PTK). We have previously shown in vivo that Fer kinase plays a key role in neutrophil recruitment and epithelial barrier dysfunction during endotoxin (LPS)-induced inflammation.
AIM: In this study we examined the role of Fer kinase in two different models of intestinal inflammation where bacterial products have been found to play a role (a) 2, 4, 6-trinitrobenzene sulphonic acid (TNBS)-induced model of colitis and (b) the cecal ligation and puncture (CLP)-induced model of polymicrobial sepsis.
METHODS: Wild type (WT) or Fer null (Fer^DR/DR) mice were used between 6-10 weeks of age. Colitis was induced by a single intrarectal administration of injection of 0.1 ml TNBS (60 mg/ml in 30% ethanol). Healthy wild type or Fer^DR/DR mice were also studied as controls. Animals were killed three, or seven days post-induction of colitis. Macroscopic inflammatory scores were quantified and myeloperoxidase activity (MPO) as an indication of neutrophil recruitment was assessed. Sepsis was induced by CLP method briefly as follows: mice were anaesthetized and the cecum exteriorized through a small midline incision. The cecum was punctured with 1 pass of an 18-gauge needle and a small amount of stool was squeezed out through both holes. Mice were allowed to recover and after 6 hours the clinical syndrome score was assessed based on activity, body temperature, and presence of other signs like hunched or lateral recumbency, starry fur, or lethargy. Intestinal MPO activity was assessed after 6 h. Sham operated animals were used as controls.
RESULTS: (a) TNBS-model: In WT mice, TNBS induced a significant increase in macroscopic inflammation and MPO activity at 3 days.
A significant increase in macroscopic inflammatory score was observed in Fer^DR/DR mice (3.012±0.7) relative to wild type mice (1.58±0.04) (P<0.05) at 3 days. An exacerbated increase in MPO activity was observed in colon tissue from Fer^DR/DR (12.57±3.4) relative to WT mice (4.8±0.25) at 3 days demonstrating an enhanced influx of granulocytes into the tissue. Preliminary data suggest the exacerbated response is maintained at 7 days. (b) Polymicrobial sepsis induced by CLP: A significant increase in the clinical syndrome score was observed in WT mice with CLP (2.25±0.25) compared with sham group (0.66±0.66). Interestingly, Fer^DR/DR mice showed a significantly higher (P<0.05) clinical score (3.66±0.66) and small intestinal MPO activity compared with both WT group with CLP and sham group. Granulocyte infiltration to the lung was also significantly enhanced in Fer^DR/DR mice demonstrating systemic activation of leukocytes.
CONCLUSION: Fer kinase plays a role in intestinal inflammation possibly through regulation of neutrophil recruitment.

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