Trefoil factor family (TFF) peptides of normal human Vater's ampulla

Vater's ampulla is of great clinical relevance with regard to the influx of chyme, ascending inflammation, intubation during diagnostic and therapeutic endoscopic maneuvers, therapeutic papillotomy and, especially, the formation of malignancies. Little is known about the distribution of trefoil factor family (TFF) peptides in the ampulla. We have therefore examined TFF peptide distribution in the normal ampulla of Vater and compared it with that in duodenal mucosa and Brunner's glands. Expression and synthesis of TFF peptides in Vater's ampulla and duodenum was investigated by reverse transcription-polymerase chain reaction, Western blot and immunohistochemistry. The samples studied originated from 30 autopsy cases with short postmortem intervals. TFF3 was expressed in the ampulla of Vater. mRNA expression of TFF1 was detected in only approximately 25% of the investigated samples. Western blot revealed the production of TFF3 and immunohistochemistry showed that TFF3 was the product of goblet cells. TFF peptide composition of Vater's ampulla varied in comparison with that in the duodenum regarding TFF2 expression. The ampulla of Vater thus has a unique profile of TFF peptide production, supporting the hypothesis that the ampulla is an autonomous organ. The observed differences in the TFF peptide distribution between the duodenum and Vater's ampulla favour the investigation of TFF peptides as prognostic markers in the classification of ampullary carcinomas.

Metaplasia of the duodenum shows a Helicobacter pylori-correlated differentiation into gastric-type protein expression

The origin of gastric metaplasia of the duodenum (GMD) remains enigmatic. We studied expression of mucins and trefoil peptides in GMD to gain insight into its phenotype and origin. We examined duodenal tissue of 95 patients (0 to 83 years old, 26 with gastric Helicobacter pylori infection) for the presence of GMD. Expression was examined immunohistochemically of secretory mucins (MUC2, MUC5AC, MUC5B, and MUC6), trefoil peptides (TFF1, TFF2, and TFF3), and sucrase-isomaltase (SI). GMD, found in 37 patients, correlated positively to gastric H. pylori infection, age, and villus atrophy. MUC2 and TFF3, expressed in normal goblet cells, were absent from 100% and 87% of GMD, respectively. GMD ubiquitously expressed MUC5AC, whereas MUC5AC expression in adjacent goblet cells was closely correlated with the extent of GMD. TFF1, TFF2, and MUC6 were found in 84%, 92%, and 65% of GMD, respectively. MUC5B was absent from epithelium and GMD. SI, expressed by villus enterocytes, was absent from GMD. Brunner's glands ubiquitously expressed MUC5B, MUC6, and TFF2. GMD was characterized by the expression of gastric-type proteins MUC5AC, MUC6, TFF1, and TFF2 and the absence of intestinal markers MUC2, TFF3, and SI. In terms of the location of metaplastic cells, our results suggest that epithelial cells migrating toward villus tips switch to gastric-type secretory cells. Positive correlation with infection suggests an inductive role H. pylori in the development of GMD.

Brunner's glands: a structural, histochemical and pathological profile

Brunner's glands are unique to mammalian species and in eutherians are confined primarily to the submucosa of the proximal duodenum. In the majority of species examined, they begin at the gastrointestinal junction and extend for variable distances distally in the wall of the proximal small intestine. Ducts of individual glands empty either directly into the intestinal lumen or unite with overlying intestinal glands (crypts of Lieberkühn) dependent on the species. Secretory units of Brunner's glands consist of epithelial tubules that show frequent distal branchings. The secretory units, with the exception of those found in rabbits and horses, consist primarily of a mucin producing cell type. However, other cell types normally associated with the overlying intestinal epithelium may be encountered scattered within the secretory units reflecting the developmental origin of these glands. Secretion from Brunner's glands contributes to a layer of mucus that forms a slippery, viscoelastic gel that lubricates the mucosal lining of the proximal intestinal tract. The unique capacity of this mucus layer to protect delicate underlying epithelial surfaces is due primarily to the gel-forming properties of its glycoprotein molecules. Mucin glycoproteins produced by Brunner's glands consist primarily but not exclusively of O-linked oligosaccharides attached to the central protein core of the glycoprotein molecule. Human Brunner's glands produce class III mucin glycoproteins and are thought to be the product of mucin gene MUC6 which is assigned to chromosome 11 (11p15-11p15.5 chromosome region). In addition to mucin glycoproteins and a limited amount of bicarbonate, numerous additional factors (epidermal growth factor, trefoil peptides, bactericidal factors, proteinase inhibitors, and surface-active lipids) have been identified within the secretory product of Brunner's glands. These factors, incorporated into the mucus layer, guard against the degradation of this protective barrier and underlying mucosa by gastric acid, pancreatic enzymes, and other surface active agents associated with this region. Yet other factors produced by Brunner's glands function to provide active and passive immunological defense mechanisms, promote cellular proliferation and differentiation, as well as contribute factors that elevate the pH of luminal contents of this region by promoting secretion of the intestinal mucosa, pancreatic secretion and gall bladder contraction. Additional insights concerning the role of Brunner's glands in the mammalian gastrointestinal tract as well as their possible evolution in this class of vertebrates have been gained from a basic understanding of their pathobiology.

Dynamic regulation of mucus gel thickness in rat duodenum

We examined the dynamic regulation of mucus gel thickness (MGT) in vivo in rat duodenum in response to luminal acid, cyclooxygenase (COX) inhibition, and exogenous PGE(2). An in vivo microscopic technique was used to measure MGT with fluorescent microspheres in urethan-anesthetized rats. Duodenal mucosa was topically superfused with pH 7.0 or pH 2.2 solutions with or without PGE(2) and indomethacin treatments. Glycoprotein concentration of duodenal loop perfusates was measured with periodic acid/Schiff (PAS) or Alcian blue (AB) staining. MGT and perfusate glycoprotein concentration were stable during a 35-min perfusion with pH 7.0 solution. Acid exposure increased MGT and PAS- and AB-positive perfusate glycoprotein concentrations. Indomethacin pretreatment increased both PAS- and AB-positive perfusate glycoprotein at baseline; subsequent acid superfusion decreased perfusate glycoproteins and gel thickness. PGE(2) (1 mg/kg iv) simultaneously increased MGT and PAS-positive perfusate glycoprotein concentrations followed by a transient increase in AB-positive glycoprotein concentration, suggesting contributions from goblet cells and Brunner's glands. Parallel changes in MGT and perfusate glycoprotein concentration in response to luminal acid and PGE(2) suggest that rapid MGT variations reflect alterations in the balance between mucus secretion and exudation, which in turn are regulated by a COX-related pathway. Luminal acid and PGE(2) augment mucus secretion from goblet cells and Brunner's glands.

Presence of sorbin in human digestive tract and endocrine digestive tumours

BACKGROUND

Sorbin, a 153 amino acid peptide isolated from porcine intestine, was localised by immunohistochemistry in endocrine cells of the intestinal mucosa and pancreas and in the enteric nervous system in the pig.

AIMS

To identify sorbin cells in normal human digestive tissues and to explore the expression of sorbin in 37 digestive endocrine tumours: 14 intestinal carcinoid tumours and 23 endocrine pancreatic tumours including six insulinomas.

METHODS

Two polyclonal antibodies against the C-terminal and the N-terminal sequences of porcine sorbin raised in rabbit were used to evaluate sorbin expression by immunohistochemistry.

RESULTS

In the human digestive tract, sorbin, characterised by both C-terminal and N-terminal immunoreactivity, was found in enterochromaffin cells of the gastric and intestinal epithelium from the pyloric junction to the descending colon. C-Terminal sorbin immunoreactivity alone was found in plexii from the enteric nervous system and in some insulin-containing cells of normal pancreas. C-Terminal and N-terminal antibodies disclosed sorbin in five of 14 intestinal carcinoid tumours; C-terminal antibody alone disclosed a C-terminal sorbin peptide in two of six insulinomas and three of 17 endocrine pancreatic tumours. The presence of sorbin was not associated with a specific clinical syndrome.

CONCLUSIONS

Sorbin is present in the digestive tract in several forms. It is expressed in some intestinal and pancreatic endocrine tumours.

The expression of pepsinogen c mRNA in normal gastroduodenal mucosa and the gastric ulcer margin of the rat

During the healing of experimental gastric ulcers in the oxyntic mucosa, there is a dedifferentiation of the glands in the ulcer margin: previous studies have shown that the parietal cells lose their capacity to produce HCl, and mucous cells replace the zymogen cells. Primarily, we wished to investigate whether or not the glands of the ulcer margin transcribe mRNA for pepsinogen; secondly we also wanted to locate such transcription in other parts of the gastroduodenal epithelium. For this purpose, we first established the baseline for distribution of pepsinogen mRNA in normal rats. We then studied its location in the margin of ulcers in the corpus region after 1-15 days of healing. Formaldehyde-fixed paraffin sections were used for in situ hybridization of mRNA for pepsinogen C, utilizing radioactive riboprobes. The normal gastroduodenal mucosa showed widespread hybridization: the signal was particularly strong in the zymogen cells; weaker signals were obtained from the mucous neck cells, and the cells of the cardiac, antral, and Brunner glands. Specific hybridization was weak or absent in the ulcer margin during the entire period studied. It is concluded that the capacity to produce pepsinogen C is significantly reduced or absent in the gastric ulcer margin during the first 15 days of healing; this should reduce the risks of peptic attack on the delicate scar and margin tissues during ulcer healing.

Expression of trefoil peptides pS2 and human spasmolytic polypeptide in gastric metaplasia at the margin of duodenal ulcers

Duodenal ulcers are associated with gastric metaplasia in the duodenum, both at the ulcer margin and at more distant sites in the duodenal bulb. pS2 and human spasmolytic polypeptide (hSP) are secretory peptides expressed in gastric epithelial cells and in gastric metaplasia. As these peptides may be important in ulcer healing, this study investigated the possibility that the expression of pS2 and hSP is increased in gastric metaplasia at the margin of duodenal ulcers. Duodenal bulb biopsy specimens from 12 duodenal ulcer patients were assessed. Sections were immunostained with monoclonal antibodies for pS2 and hSP. Cytoplasmic stain intensities were measured by an image analysis system and expressed as integrated optical density (IOD) units, In situ hybridisation for pS2 and hSP mRNA was carried out on parallel sections. Duodenal sections were also stained with diatase periodic acid Schiff/alcian blue to localise areas of gastric metaplasia. pS2 antigen staining in the duodenum was restricted to surface epithelial cells, and hSP to acinar and ductular components of Brunner's gland. mRNA localisation corresponded to immunostaining cells. In gastric metaplasia, pS2 expression was greater at the ulcer margin than away from the ulcer, as judged by the intensity of antibody staining (mean IOD units (SEM), 20.6 (3.3) v 9.5 (3.0); p < 0.001). There was a trend towards greater hSP staining at the ulcer margin but this did not achieve statistical significance. These findings support the putative role of pS2 and possible hSP in mucosal healing and providy further evidence for an autocrine 'ulcer-gastric metaplasia-repair' loop involving these trefoil peptides.

Immunohistochemical study of the distribution of endocrine cells in the gastrointestinal tract of the lesser mouse deer (Tragulus javanicus)

The occurrence and distribution of endocrine cells in the gastrointestinal tract of the lesser mouse deer, Tragulus javanicus, were studied immunohistochemically. Fourteen types of endocrine cells immunoreactive for serotonin, somatostatin, enteroglucagon, pancreatic glucagon, bovine pancreatic polypeptide (BPP), gastrin, substance P, motilin, gastric inhibitory polypeptide (GIP), cholecystokinin (CCK), methionine-enkephalin-Arg6-Gly7-Leu8 (MENK-8), secretin, neurotensin, peptide tyrosine tyrosine (PYY) and chromogranin were revealed. Chromogranin-, serotonin-, somatostatin- and enteroglucagon-immunoreactive cells were detected in all regions examined, while pancreatic glucagon-immunoreactive cells, except in the proper gastric gland region, were not found in other regions of the gastrointestinal tract. Few BPP-immunoreactive cells in either the proper gastric gland or pyloric gland regions and abundant gastrin-immunoreactive cells in the pyloric gland region were observed. Restricted distributions of substance P-, GIP-, gastrin-, motilin-, CCK-, MENK-8-, secretin-, neurotensin- and BPP-immunoreactive cells in the small intestine, and BPP-, substance P-, PYY- and motilin-immunoreactive cells in the large intestine were noted. The important findings include the presence of BPP-immunoreactive cells in the abomasum, pancreatic glucagon-immunoreactive cells in the proper gastric gland region, and substance P- and motilin-immunoreactive cells in the large intestine. It is suggested that the distribution pattern of gut endocrine cells in the lesser mouse deer is more similar to that in the pig than in the domestic ruminants so far reported.

Phenotypic identity of gastric mucous neck cells and mucous cells of cardiac, pyloric, and Brunner's glands

AIM

To investigate the tissue specificity of a novel monoclonal antibody raised to a tissue fraction of normal human liver and which identified certain cells of gastric and duodenal mucosa.

METHODS

A total of 155 samples of various tissues obtained from 100 surgical specimens were fixed in cold ethanol-paraformaldehyde, embedded in paraffin wax, and 3 microns sections were studied by immunohistochemical and lectin staining procedures.

RESULTS

Immunohistochemical staining showed a major tissue specific component which was strongly expressed by mucous neck cells of the body of the stomach, glands of the cardia and pyloric antrum, and by Brunner's glands. Staining for antigen in the periductal glands of normal major biliary and pancreatic ducts was variable and relatively weaker. It was not detected elsewhere in normal intestine or in the other normal tissues tested. Barrett's mucosa of gastric cardia type, and pyloric gland metaplasia in the gall bladder and small bowel affected with Crohn's disease stained for the antigen. The tissue distribution of the antigen was identical with that of a glycoprotein, demonstrated by an induced affinity for concanavalin A following treatment of tissue sections with periodic acid. The antigen was not sensitive to sialidase.

CONCLUSIONS

The tissue component identified (designated here as antigen D10) seems to be characteristic of certain differentiated epithelial cells derived from that part of foregut giving rise to stomach, duodenum, and biliary and pancreatic ducts. The antibody will be of use in investigating pathological processes involving tissue differentiation at these sites, and in the oesophagus and intestines.

Determination of the histological distribution of insulin like growth factor 1 receptors in the rat gut

The histological distribution of insulin like growth factor 1 (IGF 1) receptors in the rat gut was studied. Immunostaining of IGF 1 receptors identified localisation on the villus epithelium, in the crypts, and in Brunner's glands of the small intestine. These tissues represent areas of high cell growth/differentiation, division, and macromolecular synthesis respectively, which constitute biological activities long associated with IGF 1. Cellular localisation of IGF 1 receptors was seen in the lamina propria by IGF 1 receptor immunostaining and ligand binding of biotinylated IGF 1. IGF 1 receptor immunostaining in the spleen showed receptor localisation to the splenic pulp thus pointing to macrophages as the possible IGF 1 receptor positive cells in the lamina propria. The results further implicate IGF 1 as an important growth factor in gut maintenance.

Ulcer-associated cell lineage ('pyloric metaplasia') in Crohn's disease: a lectin histochemical study

Chronic intestinal ulceration in Crohn's disease is associated with the development of an epidermal growth factor-secreting cell lineage, or 'ulcer-associated cell lineage' (UACL). Expression of oligosaccharides by UACL was studied using a panel of 25 biotinylated lectins with an avidin peroxidase revealing system and compared with that of adult and fetal Brunner's glands, gastric antral mucosa, and 'gastric metaplasia' within the duodenum, in order to clarify further the interrelationships of these lineages. UACL was obtained from ileal resections performed for Crohn's disease. Lectin binding of the glandular component of UACL closely resembled that of antral mucosal glands and also that of fetal and adult Brunner's glands. Lectin binding of the ductal component of immature UACL, in which a surface component had not developed, resembled that of the gland. The surface and ductal components of mature UACL showed a distinct lectin-binding profile, which was very different from that of the gland, but closely resembled that of antral foveolar epithelium and 'gastric metaplasia' within the duodenum. It is concluded that there is differentiation of UACL from the glandular to surface components and that oligosaccharide expression of the lineage reflects that of normal Brunner's gland and gastric antral mucosa.