MFG-E8 attenuates intestinal inflammation in murine experimental colitis by modulating osteopontin-dependent alphavbeta3 integrin signaling.

MFG-E8 (milk fat globule-epidermal growth factor 8) deficiency is strongly associated with acquisition of immune-mediated disorders due to the loss of tissue homeostasis. However, comparatively little is known regarding its functions in gastrointestinal tract disorders, in which immune homeostasis is a major concern. Herein, we report altered MFG-E8 expression in inflamed colons during the acute phase of murine experimental colitis and found that treatment with recombinant MFG-E8, but not its arginine-glycine-aspartate mutant counterpart, ameliorated colitis by reducing inflammation and improving disease parameters. To reveal the MFG-E8-mediated antiinflammatory mechanism, we employed an in vitro system, which showed the down-regulation of NF-kappaB in an LPS-dependent manner. Additionally, MFG-E8 altered alpha(v)beta(3) integrin-mediated focal adhesion kinase phosphorylation by impeding the binding of one of its potent ligands osteopontin, which becomes activated during colitis. Taken together, our results indicated that MFG-E8 has a novel therapeutic potential for treatment of colitis.

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.

Crystal violet chromoendoscopy with mucosal pit pattern diagnosis is useful for surveillance of short-segment Barrett's esophagus.

BACKGROUND: Because of a rapid increase in the incidence of Barrett's cancer, the appropriate surveillance method for Barrett's esophagus is of interest. Methylene blue chromoendoscopy has been reported to be an effective and inexpensive method to improve biopsy surveillance of Barrett's epithelium. However, the usefulness of this method in short-segment Barrett's esophagus cases is still controversial. AIMS: This study was undertaken to evaluate the abilities of crystal violet and methylene blue chromoendoscopy to detect potentially dysplastic Barrett's epithelium in cases with short-segment columnar-appearing epithelium of the esophago-gastric junction. PATIENTS AND METHODS: Four hundred patients with endoscopically suspected short-segment Barrett's esophagus were enrolled and randomly assigned to receive chromoendoscopy with 0.05% crystal violet, 0.1% crystal violet, 0.5% methylene blue, or 1.0% methylene blue. During crystal violet and methylene blue chromoendoscopy, biopsy specimens were obtained from stained and unstained columnar-appearing epithelium of the esophago-gastric junction, and the detection rates of Barrett's epithelium were evaluated. The value of pit pattern diagnosis was also evaluated as a possible way to detect dysplastic Barrett's epithelium. RESULTS: Chromoendoscopy with 0.05% crystal violet detected histologically confirmed Barrett's epithelium with the highest sensitivity (89.2%) and specificity (85.7%). Crystal violet clearly stained both dysplastic and nondysplastic Barrett's epithelia and made the surface pit pattern easy to observe without using magnifying endoscopy. CONCLUSIONS: The combination of crystal violet chromoendoscopy and pit pattern diagnosis is considered to be useful for the surveillance of short-segment Barrett's esophagus.

Growth inhibition of esophageal squamous carcinoma cells by peroxisome proliferator-activated receptor-gamma ligands.

The growth of human cancer cells expressing peroxisome proliferator-activated receptor-gamma (PPAR-gamma) has been reported to be inhibited by PPAR-gamma ligands. In esophageal squamous-cell carcinoma cell lines T.T, T.Tn, and EC-GI-10, we detected expression of PPAR-gamma and investigated the effects of PPAR-gamma ligands on these cell lines in vitro with the use of troglitazone, pioglitazone, and 15d-PGJ2. Marked growth inhibition by the PPAR-gamma ligands was observed in all cases. The growth-inhibitory effect was evidenced by a dose-dependent inhibition of deoxyribonucleic acid synthesis and was associated with altered cell-cycle progression manifesting G1 arrest. Cell-cycle arrest in T.Tn cells induced by troglitazone could be correlated with an increased level of cyclin-dependent kinase inhibitor p27(Kip1), p21(Cip1/Waf1), and p18(Ink4c). Moreover, troglitazone treatment increased the expression of interleukin-1 alpha, a multifunctional cytokine implicated in antitumor immunity. These findings suggest that troglitazone and other PPAR-gamma ligands have adjuvant or neoadjuvant therapeutic potentials in esophageal cancer.

Effect of a gastrin/cholecystokinin B receptor antagonist, S-0509, on the omeprazole-induced proliferation of gastric mucosa in rats.

Hypergastrinemia is known to cause hyperplasia of the gastric mucosa, especially in gastric enterochromaffinlike (ECL) cells. In some clinical conditions causing hypergastrinemia, such as long-term gastric-acid inhibition and gastric-mucosa atrophy, hyperplastic ECL cells may develop into gastric carcinoid tumors. A newly developed gastrin-receptor antagonist, S-0509, has been reported to block gastrin-induced stimulation of gastric-acid secretion. We therefore investigated whether S-0509 inhibits the omeprazole- and gastrin-stimulated hyperproliferation of gastric mucosa, especially of ECL cells. Daily administration of omeprazole and gastrin in male Sprague-Dawley rats induced marked hypergastrinemia and increased proliferation of gastric-mucosa cells. The numbers of ECL cells and of ECL cells producing messenger RNA for regenerating gene, a potent growth factor for gastric-mucosa cells, were also augmented by long-term administration of omeprazole and gastrin. Coadministration of S-0509 with omeprazole or gastrin almost completely inhibited the omeprazole- and gastrin-induced changes in gastric mucosa, including mucosal thickening and ECL hyperplasia. S-0509 did not induce gastric-mucosa atrophy, even when administered for as long as 4 weeks. In summary, we have found that a newly developed gastrin receptor antagonist, S-0509, inhibits omeprazole- and gastrin-induced mucosal hyperplasia, especially ECL-cell hyperplasia, in rats.

Cardiovascular risk factors in subjects with Helicobacter pylori infection.

BACKGROUND: It has been proposed that Helicobacter pylori infection is related to cardiovascular disease, although this has not been fully investigated. The aim of this study was to investigate whether H. pylori infection is associated with cardiovascular risk factors. SUBJECTS AND METHODS: One thousand six hundred and fifty people undergoing annual medical checks at Shimane Institute of Health Science between September 1998 and August 1999 were enrolled. Gender, age, body mass index, habitual smoking and drinking, systolic and diastolic blood pressure, serum level of total cholesterol, triglyceride, high-density lipoprotein cholesterol (HDLC), blood glucose, leukocyte count and hemoglobin were compared between H. pylori seropositive and seronegative cases. RESULTS: In H. pylori seropositive individuals, HDLC was significantly lower than that in seronegative individuals. After adjustment for possible confounding factors (gender, age, BMI, smoking and drinking habits), mean HDLC in H. pylori-seropositive and seronegative individuals were 56.1 and 58.2 mg/dl, respectively (p <.005). The percentage of the elderly (over 50 years old) individuals with HDLC < 35 mg/dl in H. pylori seropositive and seronegative groups were 7.4% and 4.7%, respectively (p <.001). In addition, the lower HDLC level was accompanied by an increased leukocyte count. CONCLUSION: Long-term infection with H. pylori may have an important role in decreasing the serum HDLC concentration.

Lafutidine, a novel histamine H2-receptor antagonist, increases serum calcitonin gene-related peptide in rats after water immersion-restraint stress.

Lafutidine is a novel histamine H(2)-receptor antagonist with a potent and long-lasting anti-acid secretory effect that has also been found to have a potent gastroprotective effect. We investigated the effect of lafutidine on gastric mucosal injury induced in rats with the use of water-immersion restraint stress (WRS) by examining serum calcitonin gene-related peptide (CGRP) concentrations, which we measured with the use of an enzyme immunometric assay. WRS-induced mucosal erosive injury in the stomach was reduced significantly by both lafutidine and famotidine pretreatment (from 7.79 +/- 2.02 mm(2) to 3.09 +/- 0.74 mm(2) and 4.05 +/- 1.18 mm(2), respectively). A single administration of lafutidine or famotidine did not change the serum CGRP concentration from the control value when these drugs were administered without WRS. Lafutidine pretreatment before WRS caused a significant increase in serum CGRP concentration compared with famotidine (lafutidine, 86.64 +/- 9.52 pg/mL; famotidine, 47.55 +/- 4.35 pg/mL; control, 58.43 +/- 6.07 pg/mL). Our results suggest that lafutidine augments CGRP release from the rat stomach when administered before the induction of WRS.

Essential role of MD-2 in TLR4-dependent signaling during Helicobacter pylori-associated gastritis.

TLR4, a member of pattern recognition receptors, is the main receptor of LPS. MD-2 physically associates with TLR4 on the cell surface and confers LPS responsiveness. Helicobacter pylori LPS is one of the major virulence factors for induction of gastritis. We demonstrated in this study the role of MD-2 in TLR4-dependent signaling in H. pylori-associated gastritis. Gastric biopsy samples collected from patients with and without H. pylori infection and four gastric cancer cell lines were used for this study. TLR-4 and MD-2 expression in biopsy specimens and the cell lines was examined by using RT-PCR. Localization of TLR-4 in histological sections was evaluated by immunohistochemistry. For in vitro functional assays, we established stable transfectants of AGS cells expressing TLR4 and MD-2. Cellular distribution of TLR4 was examined by flow cytometry. NF-kappaB activation and activation of IL-8 and MD-2 promoters were assessed by reporter gene assay. H. pylori infection up-regulated the TLR4 and MD-2 expression in gastric mucosa. TLR4 staining was observed predominantly in epithelial cells, located in both the cytoplasm and at the apical surface. MD-2 transfection in AGS cells markedly increased cell surface expression of TLR4 and augmented the activation of NF-kappaB and IL-8 promoter upon stimulation with H. pylori LPS. Live H. pylori also stimulated transcriptional activation of MD-2. This study revealed that MD-2 expression is elevated in gastric epithelial cells during H. pylori infection, suggesting that the TLR4/MD-2 system is a potent receptor complex involved in the response to H. pylori LPS in the stomach.