Background/purpose: Microinjection of a Fisher (F344) rat zygote with human HLA-B27 and beta2-microglobulin genes induces spontaneous chronic gastrointestinal (GI) inflammation similar to lesions seen in patients with inflammatory bowel disease (IBD). This study was designed to evaluate the potential therapeutic benefit of GLP-2, an intestinal growth factor, in this transgenic rat model of IBD.
Methods: Five F344 (control) and 10 HLA-B27 (on a F344 background) rats at 25 weeks of age were used. Rats were divided into the following 3 groups: group 1, F344 rats, no treatment (n = 5); group 2, HLA-B27, no treatment (n = 5); and group 3, HLA-B27, treated with a 14-day systemic infusion (via the jugular vein) of GLP-2 at 50 microg/kg/d (n = 5). After infusion, all rats underwent laparotomy, and the intestine from the ligament of Treitz to the rectum was harvested. Total mucosal damage (percent surface area) was measured using image analysis software (Sigmascan 2.0). Microscopic analysis was performed by a blinded reviewer and scored as follows: 0, no inflammation; 1, mild inflammation; 2, moderate inflammation; and 3, severe inflammation. Colonic mucosal total RNA was assayed for tumor necrosis factor alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin-2 (IL-2), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH), internal standard, mRNA by reverse transcriptase polymerase chain reaction. Statistical analysis was performed using analysis of variance (ANOVA) and expressed as mean +/- SEM.
Results: Normal F344 rats did not show evidence of gross or histological lesions in the small or large intestine. GLP-2 reduced total mucosal damage from 9.0% +/- 0.7% in group 2 to 0.9% +/- 0.5% in group 3 (P < .01). The histological lesion score was reduced from 7.0 +/- 0.6 in group 2 to 4.4 +/- 0.8 in group 3 (P < .01). Furthermore, GLP-2 reduced the mean band intensity (MBI) of TNF-alpha (0.4 +/- 0.04 in group 2 to 0 in group 3, P < .01) and IFN-gamma (0.3 +/- 0.02 in group 2 to 0 in group 3, P < .01).
Conclusions: These data show for the first time that GLP-2 significantly reduces gross (90% decrease) and histological (40% decrease) lesions in this rat model of IBD. This is further supported by a significant decrease in gene expression of the inflammatory mediators TNF-alpha (100% decrease) and IFN-gamma (100% decrease). These data suggest a potential therapeutic role for GLP-2 in IBD.