B. Orsini

Expression of epidermal growth factor, transforming growth factor-alpha and their receptor in the human oesophagus.

SummaryIncreasing evidence indicates that epidermal growth factor and transforming growth factor-α are involved in the maintenance of oesophageal mucosal integrity. However, their cellular origin and the exact localization of their receptor in the oesophagus are still unclear. Therefore, we examined the expression of the two growth factors and their shared receptor in the normal human oesophagus at both mRNA and protein level, by immunohistochemistry, in situ hybridization and reverse transcription-polymerase chain reaction. In addition to being expressed in the proliferative compartment of the oesophageal epithelium, the receptor was found in a variety of cells, including smooth muscle cells, submucosal gland cells and the epithelium lining their ducts. Immunohistochemically, the pattern of distribution of epidermal growth factor paralleled that of its receptor. In situ hybridization demonstrated epidermal growth factor mRNA expression in the oesophageal epithelium and submucosal glands. Additionally, amplified transcripts of predicted size were detected by reverse transcription-polymerase chain reaction, thus confirming that authentic transcripts of the growth factor exist in the normal human oesophagus. Transforming growth factor-α mRNA and protein expression, while similar to that of epidermal growth factor, predominated in the more differentiated cell layers of the stratified squamous epithelium. These results demonstrate that the normal oesophagus can synthesize both growth factors. Moreover, the peculiar distribution of these peptides and the concomitant expression of their receptor in multiple cell types suggest that the two growth factors may exert diverse physiological functions in the oesophagus and participate in defence and reparative events following mucosal injury.

Helicobacter pylori cag Pathogenicity Island Is Associated with Reduced Expression of Interleukin-4 (IL-4) mRNA and Modulation of the IL-4δ2 mRNA Isoform in Human Gastric Mucosa

ABSTRACT Interleukin-4 (IL-4) and IL-4δ2 mRNA gastric expression was evaluated in healthy subjects and patients who did not have ulcers but were infected with Helicobacter pylori with or without the cag pathogenicity island (cag PAI). IL-4 mRNA was physiologically expressed by gastric epithelium and negatively influenced by H. pylori. Also, nonepithelial cells in the lamina propria of H. pylori-infected patients expressed IL-4 mRNA, whereas IL-4δ2 mRNA was found only in cag PAI-negative patients. Thus, gastric IL-4 takes part in the local immune response to H. pylori.

Localization of epidermal growth factor/transforming growth factor-α receptor in the human gastric mucosa

Current evidence indicates that epidermal growth factor (EGF) and transforming growth factor-α (TGF-α) play a pivotal role in the maintenance of gastric mucosal integrity, via binding to a common cell-surface receptor (EGF/TGF-α receptor). We examined the distribution and cellular sites of synthesis of EGF/TGF-α receptor in normal human gastric mucosa by immunohistochemical and in situ hybridization techniques. Intense EGF/TGF-α receptor immunoreactivity was observed in the basal cytoplasm and along basolateral membranes of mucus neck cells, foveolar columnar cells, and surface epithelial cells facing the gastric lumen. Parietal cells and mucus-secreting pyloric gland cells displayed a distinct basolateral immunostaining, whereas the luminal membrane was unstained. Immunoreactivity was also noted in spindle-shaped cells of the lamina propria and in smooth muscle cells of the muscularis mucosae and muscularis propria. In situ hybridization revealed EGF/TGF-α receptor RNA transcripts in all cell types displaying positive immunoreaction. These results suggest a physiological role for EFG/TGF-α in the regulation of multiple gastric functions. The receptor distribution at the luminal aspect of the gastric mucosa provides the anatomical basis for a possible interaction of gastric juice EGF (or TGF-α) with cells of the mucosal surface, whereas the expression of EGF/TFG-α receptor in cells which are not in direct contact with the gastric lumen is consistent with blood-mediated or paracrine/ autocrine mechanisms of EGF/TGF-α action on these cells.Current evidence indicates that epidermal growth factor (EGF) and transforming growth factor-alpha (TGF-alpha) play a pivotal role in the maintenance of gastric mucosal integrity, via binding to a common cell-surface receptor (EGF/TGF-alpha receptor). We examined the distribution and cellular sites of synthesis of EGF/TGF-alpha receptor in normal human gastric mucosa by immunohistochemical and in situ hybridization techniques. Intense EGF/TGF-alpha receptor immunoreactivity was observed in the basal cytoplasm and along basolateral membranes of mucus neck cells, foveolar columnar cells, and surface epithelial cells facing the gastric lumen. Parietal cells and mucus-secreting pyloric gland cells displayed a distinct basolateral immunostaining, whereas the luminal membrane was unstained. Immunoreactivity was also noted in spindle-shaped cells of the lamina propria and in smooth muscle cells of the muscularis mucosae and muscularis propria. In situ hybridization revealed EGF/TGF-alpha receptor RNA transcripts in all cell types displaying positive immunoreaction. These results suggest a physiological role for EGF/TGF-alpha in the regulation of multiple gastric functions. The receptor distribution at the luminal aspect of the gastric mucosa provides the anatomical basis for a possible interaction of gastric juice EGF (or TGF-alpha) with cells of the mucosal surface, whereas the expression of EGF/TGF-alpha receptor in cells which are not in direct contact with the gastric lumen is consistent with blood-mediated or paracrine/autocrine mechanisms of EGF/TGF-alpha action on these cells.

Helicobacter pylori cag pathogenicity island is associated with enhanced interleukin-8 expression in human gastric mucosa.

BACKGROUND In vitro studies showed that Helicobacter pylori strains carrying the cag pathogenicity island are able to induce epithelial secretion of Interleukin-8. AIMS To evaluate the assessment of cag pathogenicity island and the expression of Interleukin-8 in the gastric mucosa of Helicobacter pylori-infected patients and correlate these data with the activity of gastritis and Helicobacter pylori density. METHODS cag status was determined by polymerase chain reaction directly on gastric biopsies from 13 Helicobacter pylori+ patients with non-ulcer dyspepsia and 13 Helicobacter pylori+ with duodenal ulcer. Interleukin-8 gene transcription and protein expression were analysed by in situ hybridization and immunofluorescence, respectively. Gastritis activity and Helicobacter pylori density were also investigated. RESULTS cag was present in 20/26 of Helicobacter pylori+ patients: in 7/13 non-ulcer dyspepsia (53.8%] and in 13/13 duodenal ulcer patients (100%), (p<0.05). Interleukin-8 mRNA and protein expression in epithelial and inflammatory cells was higher in cag+ than in cag- patients (p<0.005). Gastritis activity significantly correlated with cag (p<0.05) and Interleukin-8 expression (p<0.005]. Helicobacter pylori density was enhanced in cag+ [p<0.005] and correlated with Interleukin-8 expression (p<0.0051. CONCLUSIONS The present study demonstrates that in Helicobacter pylori-infected human gastric mucosa, cag+ infection is associated with enhanced Interleukin-8 expression, higher levels of active gastritis and bacterial density, and presence of duodenal ulcer.

Serologic Detection of CagA Positive Helicobacter pylori Infection in a Northern Italian Population: Its Association with Peptic Ulcer Disease

About 60–70% of Helicobacter pylori strains possess cagA (cytotoxin associated gene A) gene and express its product CagA, a highly immunogenic 128–140kD protein. Patients infected with CagA positive strains develop serum IgG anti‐CagA. A serologic response to CagA has been detected in Helicobacter pylori infected patients with peptic ulcer more frequently than in those with gastritis alone. It is unclear whether this finding is consistent in different geographical populations. We investigated the relationship between anti‐CagA seropositivity and peptic ulcer disease in a Northern Italian population.

Role of epidermal growth factor in peptic ulcer healing

In recent years, increasing interest has been focused on peptide growth factors, and impressive progress has been made in the understanding of their role in tumor development and progression. However, evidence is mounting that peptides such as epidermal growth factor and transforming growth factor-alpha may be of much more physiological than pathological importance. This brief article is intended to give a rapid overview of the available data supporting a role for epidermal growth factor and its human homologue urogastrone in peptic ulcer healing.

Regression of duodenal gastric metaplasia in Helicobacter pylori positive patients with duodenal ulcer disease

BACKGROUND It is unclear whether the extent of duodenal gastric metaplasia is due to Helicobacter pylori and/or acid. AIMS To investigate the role of Helicobacter pylori eradication in the regression of duodenal gastric metaplasia in patients with duodenal ulcer maintained in acid suppression conditions. METHODS . Duodenal (anterior, superior inferior walls of first part of duodenum) and gastric antrum biopsies were obtained from 44 Helicobacter pylori positive duodenal ulcer patients. Helicobacter pylori infection was diagnosed by rapid urease test, histology and 13C-Urea Breath Test. Patients were treated with 20 mg omeprazole tid associated with 250 mg clarithromycin and 500 mg amoxycillin four times daily for 10 days and maintained with 20 mg omeprazole daily for 18 weeks. Control endoscopies were performed at 6 and 18 weeks after beginning treatment. RESULTS Duodenal gastric metaplasia regression was observed in all (32/32) patients in whom Helicobacter pylori was eradicated, but in only 3 out of 6 patients in whom eradication was not achieved (p<0. 001). CONCLUSIONS . The present results suggest that Helicobacter pylori eradication associated with prolonged acid suppression may represent a good therapeutic strategy to achieve duodenal gastric metaplasia regression and highlight the combined role of acid and Helicobacter pylori in the pathogenesis of duodenal gastric metaplasia.

Radioimmunoassay of epidermal growth factor in human saliva and gastric juice

A sensitive radioimmunoassay was developed for human epidermal growth factor (hEGF) in saliva and gastric juice. This method was sufficiently sensitive for an accurate measurement of hEGF in these biological fluids. The minimal detectable concentration of EGF was 30 ng/L. The imprecision profile of EGF standard curve had a CV less than 10% in the range of 0.1-3.0 micrograms/L. Serial dilution curves of saliva and gastric juice paralleled that of standard EGF. The antibody to hEGF showed no cross-reactivity with a large excess of growth factors, such as human transforming growth factor alpha, human insulin-like growth factor I, and platelet-derived growth factor (c-sis). No detectable cross-reactivity was observed with some biological gut peptides: somatostatin, gastrin, secretin or pancreatic polypeptide. The intra-assay CV for saliva and gastric juice was less than 10%, and the recoveries were 93.9 +/- 8.7% and 93.7 +/- 11.3%, respectively for saliva and gastric juice. Gel exclusion chromatography revealed hEGF-like substances, heterogeneous in size in saliva and gastric juice, the origins and physiological functions of which are unknown.

Human gastric epithelium produces IL-4 and IL-4delta2 isoform only upon Helicobacter pylori infection.

Recent evidence suggests that interleukin-4 (IL-4) is related to mucosal tolerance by which an injurious immune response is prevented, suppressed or shifted to a non-injurious response. We investigated the expression of IL-4 and its splice variant isoform IL-4δ2 in gastric epithelial cells of healthy subjects and gastritis patients infected with Helicobacter pylori (H. pylori) with or without the cag pathogenicity island (cag-PAI). IL-4 and IL-4δ2 mRNAs were evaluated in microdissected gastric epithelium and in AGS cell lines co-cultured with H. pylori B128 or SSI strains. IL-4 mRNA was consistently detected in microdissected gastric epithelial cells from healthy subjects. The IL-4 mRNA expression was low in H. pylori-infected patients, and markedly reduced in cag-PAI-positive ones. IL-4δ2 mRNA was expressed on gastric epithelium of H. pylori-infected patients, but not in healthy subjects. The IL-452 expression was lower in cag-PAI-positive than in cag-PAI-negative H. pylori infected patients. AGS cells also produced IL-4 mRNA upon SSI strain stimulation, whereas IL-4δ2 mRNA expression was detected in AGS co-cultured with either SSI or B128 strains. An inverse correlation was documented between IL-4 and IL-482 mRNA expression by microdissected gastric epithelial cells and the score of gastritis. IL-4, but not IL-452, is expressed by gastric epithelium of healthy subjects, whereas IL-452 and lesser IL-4 mRNA are detectable in the gastric epithelium of H. pylori-infected patients. Data suggest that gastric epithelial cells might regulate the balance between tolerance and immune response by the fine tuning of IL-4 and IL-4δ2 expression.

Cigarette Smoking Increases Gastric Luminal Prostaglandin F2α and Thromboxane B2 in Healthy Smokers

Pentagastrin-stimulated gastric luminal prostaglandin E2 (PGE2), 6-keto-PGF1 alpha, PGF2 alpha and thromboxane B2 (TxB2) were measured using a second antibody solid-phase enzyme immunoassay before, during and after cigarette smoking in healthy smokers. Smoking significantly increased PGF2 alpha and TxB2 concentration and output; in contrast no significant changes were found for PGE2 and 6-keto-PGF1 alpha levels. In addition, cigarette smoking caused a significant reduction in gastric juice volume and acid output but did not alter intragastric acidity. These findings may suggest a possible role of prostanoids in the response of the stomach to cigarette smoking.