Exacerbation of indomethacin-induced small intestinal injuries in Reg I-knockout mice.

Nonsteroidal anti-inflammatory drug (NSAID)-induced small intestinal injuries are serious clinical events and a successful therapeutic strategy is difficult. Regenerating gene (Reg) I protein functions as a regulator of cell proliferation and maintains intercellular integrity in the small intestine. The aim of this study was to evaluate the role of Reg I in NSAID-induced small intestinal injuries. First, to examine the effect of Reg I deficiency on such injuries, indomethacin, a widely used NSAID, was injected subcutaneously into 10-wk-old male Reg I-knockout (Reg I(-/-)) and wild-type (Reg I(+/+)) mice twice with an interval of 24 h, after which the mice were euthanized. Small intestinal injuries were assessed by gross findings, histopathology, and contents of IL-1beta and MPO in the experimental tissues. Next, we investigated the therapeutic potential of Reg I in indomethacin-induced small intestinal injuries. Recombinant Reg I protein (rReg I) was administered to 10-wk-old male ICR mice, then indomethacin was administered 6 h using the same protocol as noted above, after which small intestinal injuries were assessed after euthanasia. Our results showed that Reg I(-/-) mice had a greater number of severe small intestinal lesions after indomethacin administration. Histological examinations of the small intestines from those mice revealed deep ulcers with prominent inflammatory cell infiltration, whereas the mucosal content of proinflammatory agents was also significantly increased. In addition, rReg I administration inhibited indomethacin-induced small intestinal injuries in ICR mice. In conclusion, Reg I may be useful as a therapeutic agent in NSAID-induced small intestinal injuries.

Heparin-binding EGF-like factor augments esophageal epithelial cell proliferation, migration and inhibits TRAIL-mediated apoptosis via EGFR/MAPK signaling.

OBJECTIVE: Heparin-binding epidermal growth factor-like growth factor (HB-EGF) has been shown to stimulate the growth and migration of human keratinocytes in an autocrine or paracrine manner. Bearing in mind the preceding narratives, present study was designed to explore the role of HB-EGF on esophageal epithelial cell growth, migration and anti-apoptosis. MATERIAL AND METHODS: HET-1A and TTn cells were treated with recombinant HB-EGF, and cell proliferation and migration were assessed by MTT and Boyden chamber assays, respectively. Anti-apoptotic effects of HB-EGF was studied by Bcl-2/Bcl-xL gene expression and utilizing a TNF-related death apoptosis inducing ligand (TRAIL). RESULTS: Recombinant HB-EGF promotes human esophageal epithelial cell proliferation in a dose dependent manner, where 1 and 10 ng/ml doses were found to be most effective. HB-EGF induced cell migration was noted in TTn, but not in HET-1A cells. Recombinant HB-EGF induced the Bcl-2, Bcl-xL mRNA/protein expression in HET-1A and TTn cells. TRAIL induced the apoptosis in TTn, whereas it was significantly inhibited in HB-EGF treated conditions. Finally, we also revealed HB-EGF induced phosphorylation of EGFR and p38 MAPK in those cell lines, while all cellular functions were repressed by EGFR inhibitor AG1478. CONCLUSION: HB-EGF promotes esophageal epithelial cell proliferation, migration and induces anti-apoptotic gene expression via EGFR/p38 MAPK phosphorylation.

Prolactin induces MFG-E8 production in macrophages via transcription factor C/EBPbeta-dependent pathway.

The lactogenic hormone prolactin (PRL) regulates milk protein gene expression in mammary glands. To maintain homeostatic balance in the body, milk fat globule epidermal growth factor 8 (MFG-E8) is vital for phagocytic clearance of apoptotic cells. We investigated the effects of PRL on MFG-E8 expression in macrophages by evaluating its promoter function. Macrophages were stimulated with PRL, and the expression of MFG-E8 was determined using real-time PCR and Western blotting. The role of MFG-E8 on phagocytosis of apoptotic cells in PRL-treated macrophages was assessed using microscopy, while the response of PRL to MFG-E8 expression was evaluated using luciferase assay. Following treatment with PRL, significant up-regulations of the PRL receptor and MFG-E8 were observed in macrophages, though PRL-treated macrophages more efficiently engulfed apoptotic cells. The results of MFG-E8 promoter analysis showed considerable up-regulation of promoter activity in macrophages following PRL treatment and results from mutation analysis of the MFG-E8 promoter suggested that the C/EBPbeta binding site was responsible for PRL-induced activation of the MFG-E8 promoter. C/EBPbeta activity was found to be up-regulated in PRL-treated cells as revealed by an electrophoretic mobility shift assay (EMSA). In conclusion, PRL is a potent inducer of MFG-E8 expression in macrophages, while its effect is mediated by the presence of a responsive element in the MFG-E8 promoter.