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  • Title: Cytokine gene expression during postnatal small intestinal development: regulation by glucocorticoids.
    Author: Schaeffer C, Diab-Assef M, Plateroti M, Laurent-Huck F, Reimund JM, Kedinger M, Foltzer-Jourdainne C.
    Journal: Gut; 2000 Aug; 47(2):192-8. PubMed ID: 10896909.
    Abstract:
    BACKGROUND: In the intestinal mucosa, numerous cytokines produced by the epithelium, fibroblasts, and immune cells were shown to affect epithelial differentiation and proliferation through epithelial-mesenchymal and epithelial-immune cell interactions. To date, the importance of cytokines in postnatal development of the rat small intestine has not been established. AIM: To investigate the developmental changes in expression of mucosal cytokines in the postnatal maturation of the rat small intestinal epithelium and their regulation by glucocorticoids (GC). METHODS: Mucosal maturation was assessed by the onset of sucrase-isomaltase (SI) mRNA, analysed by in situ hybridisation. The amount of transforming growth factor beta1 (TGF-beta1), beta2 (TGF-beta2), tumour necrosis factor alpha (TNF-alpha), interleukin 1beta (IL-1beta), and TGF-alpha was analysed by reverse transcription-polymerase chain reaction (RT-PCR) in mucosal extracts from weaning (14-21 days old) and adult rats, or one day after an injection of hydrocortisone (HC) in 11 day old rats. Similarly, expression of cytokines and the regulatory effect of GC were studied on cultured subepithelial myofibroblasts cloned from postnatal jejunum and ileum cultured in the absence or presence of dexamethasone (DX). RESULTS: TGF-beta1, TGF-beta2, and IL-1beta decreased during the third week of life while levels of TNF-alpha increased and TGF-alpha remained constant. In parallel, SI transcripts increased and showed a progressive accumulation in the apical part of the enterocytes first localised at the base of the villi from 18 days onwards. Interestingly, precocious induction of SI mRNA by HC paralleled the decrease in expression of TGF-beta isoforms and of IL-1beta. All cytokines were expressed in the myofibroblast cell lines. In addition, the results showed that TNF-alpha was differentially expressed in basal culture conditions and after DX stimulation in jejunal and ileal myofibroblasts. DX decreased IL-1beta but not the TGF-beta isoforms, similar to that in vivo. CONCLUSIONS: This study shows that mucosal cytokines are developmentally regulated and that GC are potentially involved in this regulation in parallel with maturation of the gut mucosa at weaning.
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