Abstract 1222 Poster Session II, Sunday, 5/2 (poster 54)

Intestinal Trefoil Factor (ITF or TFF3), a small peptide secreted at the mucosal surface by goblet cells throughout the mature intestine, has been shown to play an important role in the maintenance and repair of the intestinal mucosal barrier. We have previously demonstrated that ITF expression is developmentally regulated and its expression is deficient in premature rats (Lin J, et al. Pediatric Res 1998;43:50A). The deficiency in ITF expression may play a role in the susceptibility of premature infants to necrotizing enterocolitis (NEC). Since glucocorticoids are known to promote intestinal maturation and prenatal steroid treatment has been shown to be associated with a decreased incidence of NEC, we tested the hypothesis that ITF expression in intestinal epithelial cells can be upregulated by glucocorticoids.

Methods: Human intestinal epithelial cell lines LS174T, COLO205, COLO320DM, Caco2, HT29 and LOVO cells were screened for endogenous ITF mRNA expression by Northern blot analysis. Cells were grown to 80% confluence in appropriate media and treated with dexamethasone (DXM) at concentrations of 10-6 M and 10-5 M for 48 hours. Control plates were treated with media alone. Total RNA was prepared by LiCl centrifugation and Northern blots were performed with an antisense human ITF riboprobe. To test the effect of steroids in vivo, a total of 15 newborn Sprague-Dawley rats from the same litter were equally divided into 3 groups immediately after birth. The control group pups received normal saline, the low dose DXM group received DXM at a dose of 0.25 mg/kg intraperitoneal (i.p.) q 12 hours for 48 hours and the high dose DXM group received DXM at a dose of 0.50 mg/kg i.p. q 12 hours for 48 hours. At 48 hours, total RNA was prepared from the entire small intestine and colon collected from the sacrificed rat pups. Northern blot analysis was performed using a specific rat ITF riboprobe.

Results: LS174T and COLO205 have relatively high endogenous ITF mRNA expression, Caco2 and HT29 cells have much lower ITF mRNA expression. DXM did not alter endogenous ITF mRNA expression in any of these 4 cell lines at the doses tested. The newborn rats receiving DXM failed to gain weight and even lost weight compared to the control group. The weight change in the control group was +21.5±7.8% (mean±SD) versus -1.7±7.7% in low dose DXM group and -5.8±4.1% in high dose DXM group (P<0.001, ANOVA). ITF mRNA expression in intestinal tissues was similar in the three groups.

Conclusions: ITF gene expression in intestinal epithelial cells is not regulated by glucocorticoids either in vitro or in vivo. The effect of glucocorticoids on the incidence of NEC is unlikely due to an increase in ITF gene expression.