Origin and migratory pathways of the eleven epithelial cell types present in the body of the mouse stomach

Time-resolved transcriptomics of mouse gastric pit cells during postnatal development reveals features distinct from whole stomach development

Whole-organ transcriptomic analyses have emerged as a common method for characterizing developmental transitions in mammalian organs. However, it is unclear if all cell types in an organ follow the whole-organ defined developmental trajectory. Recently, a postnatal two-stage developmental process was described for the mouse stomach. Here, using laser capture microdissection to obtain in situ transcriptomic data, we show that mouse gastric pit cells exhibit four postnatal developmental stages. Interestingly, early stages are characterized by the up-regulation of genes associated with metabolism, a functionality not typically associated with pit cells. Hence, beyond revealing that not all constituent cells develop according to the whole-organ determined pathway, these results broaden our understanding of the pit cell phenotypic landscape during stomach development.

Equine Stomach Development in the Foetal Period of Prenatal Life-An Immunohistochemical Study

The study consisted of the immunohistochemical analysis of fundic and pyloric mucosa in the equine stomach between the 4th and 11th month of gestation. The accessible material was classified into three age groups using the CRL method. The adult reference group was used to define potential differences between foetal and adult populations of gastric APUD cells. The samples were preserved, prepared, and stained according to the standard protocols. The immunohistochemical reaction was assessed using the semi-quantitative IRS method. The results were documented and statistically analysed. The most significant increase was seen in gastrin (G) cell activity. The activity of other endocrine cells (cholecystokinin (I) cells, somatostatin (D) cells, and somatotropin receptor (SR) cells) was less dynamic. This study proved that the development of APUD cells within the stomach mucosa undergoes quantitative and qualitative changes during stomach development. Our results correspond with the findings described in the accessible literature and prove a strong correlation between morphological changes in the stomach wall and the organ development, growth, and maturation.

Equine Stomach Development in the Foetal Period of Prenatal Life—A Histological and Histometric Study

Simple Summary

The prenatal development of equine stomach has been rarely elaborated. The majority of accessible literature focused on the embryonal period (ca. to the 45–50th day of gestation). The histological study of the stomach wall, including the metric measurements and the gastric gland development, filled the lack of detailed information about the processes taking place in more advanced periods of pregnancy (the foetal period). The achieved results showed that the growth rate of subsequent layers of the stomach wall provided differences comparing with the isometric growth rate of whole foetus length (CRL). The blind ventricular sac, the plicated edge margin, and the pyloric part growth rates were lower than CRL increase. The body of stomach showed a higher growth rate than the whole foetus length. The non-glandular and glandular part of gastric mucosa was distinguishable from the beginning of foetal period. The gastric glands developed the most rapidly in the body of stomach, especially in the late pregnancy. The parietal cells were visible in the gastric glands in the middle of foetal period and the chief cells could be identified in the late pregnancy. The dynamic processes occurring in the prenatal life did not finish in the moment of birth, but postnatally.

Abstract

Histological and morphometrical analysis of the stomach wall was performed during the foetal period divided into three age groups (4th–11th month of gestation). The material was taken from non-glandular (the blind ventricular sac) and glandular parts (the plicated edge margin/cardiac part, the body of stomach and the pyloric part) of the stomach. It was preserved and prepared according to the standard protocol. The histological slides were stained (H-E, Masson-Goldner and PAS). The analyses were performed using the light microscope. All measurements were statistically elaborated. The crown-rump length growth rate was estimated as isometric. The blind ventricular sac growth rate was lower than CRL (negative allometric) and the partition of stomach mucosa into non-glandular and glandular part occurred in the 1st age group. The plicated edge margin/cardiac part and the pyloric part shoved similar tendencies. Only the body of stomach demonstrated a higher growth rate than CRL (positive allometric), which can be explained due to the strongest development of fundic glands. Moreover, comparing the adult reference group to the three parts of the foetal period, all metric values were lower than those achieved prenatally. The blind ventricular sac was covered with the multiple plane epithelium. The glandular parts of stomach that formed the superficial concave areas were covered with the simple columnar epithelium in the 1st age group, which developed to the cardiac, fundic, and pyloric glands in the 2rd and 3rd age groups. The propria mucosae was built with the mesenchyme, which differentiated later to the loose connective tissue. The muscular layer of mucosa was not clearly distinguishable in the 1st age group. The muscular layer of the stomach wall was formed with myoblasts in the 1st age group and later in the 2nd and the 3rd age groups built with fusiform myocytes divided into internal and external layers. The non-differentiated cells of glandular epithelium transformed into the parietal and chief cells. The first were visible in the gastric glands of the 2nd age group. Both of them were present in the 3rd age group gastric mucosa. The PAS staining proved a moderate PAS-positive reaction in the 2rd age group, while it was estimated as intense Pas-positive in the gastric glands in the 3rd age group and was comparable to postnatal observation (the adult reference group).

Equine Stomach Development in the Fetal Period: An Anatomical, Topographical, and Morphometric Study

Studies of equine stomach prenatal development are very rare, and descriptions usually focus on the processes taking place in the embryonic period. Only general information about gastric organogenesis in the fetal period is available in embryology textbooks on domestic mammals. The material for our study included twenty half-breed horse fetuses divided into three age groups on the basis of known fetal age (verified using the CRL method). Our study consists of the topographical, morphological, and morphometrical description of stomach development between the 4th and 11th months of gestation. Even though the skeletotopy, syntopy, and holotopy of the stomach in the fetal period seems to be relatively unchanged, the organ shape and the proportions between its anatomical parts differed in fetuses from the three age groups. The achieved results were statistically elaborated to estimate the dynamics of the stomach shape. This can be described as changing from medium-wide to wide and from slightly bent to sharply bent. A nonlinear correlation of all metric values with CRL in all age groups was observed. A positive allometric growth rate of different intensity was seen in all metric parameters. All the values increased as the fetal period progressed. Only the parietal surface growth rate gradually changed from strongly positive allometric in the first age group to strongly negative allometric in the third age group. A difference between the non-glandular and glandular mucosa of the stomach was visible in the first group. Development of a well-distinguishable plicated edge margin began in the second age group together with gastric pits and gastric areas. The third age group showed a well-developed gastric groove and angular incisura.

Self-Renewal and Cancers of the Gastric Epithelium: An Update and the Role of the Lectin TFF1 as an Antral Tumor Suppressor

In 2020, gastric cancer was the fourth leading cause of cancer deaths globally. About 90% of gastric cancers are sporadic and the vast majority are correlated with Helicobacter pylori infection; whereas familial clustering is observed in about 10% of cases. Gastric cancer is now considered to be a disease originating from dysregulated self-renewal of the gastric glands in the setting of an inflammatory environment. The human stomach contains two types of gastric units, which show bi-directional self-renewal from a complex variety of stem cells. This review focuses on recent progress concerning the characterization of the different stem cell populations and the mainly mesenchymal signals triggering their stepwise differentiation as well as the genesis of pre-cancerous lesions and carcinogenesis. Furthermore, a model is presented (Lectin-triggered Receptor Blocking Hypothesis) explaining the role of the lectin TFF1 as an antral tumor suppressor possibly regulating Lgr5⁺ antral stem cells in a paracrine or maybe autocrine fashion, with neighboring antral gland cells having a role as niche cells.

Are Gastric and Esophageal Metaplasia Relatives? The Case for Barrett's Stemming from SPEM

Chronic injury and inflammation in the esophagus can cause a change in cellular differentiation known as metaplasia. Most commonly, the differentiation changes manifest as Barrett's esophagus (BE), characterized by the normal stratified squamous epithelium converting into a cuboidal-columnar, glandular morphology. BE cells can phenotypically resemble specific normal cell types of the stomach or intestine, or they can have overlapping phenotypes in disorganized admixtures. The stomach can also undergo metaplasia characterized by aberrant gastric or intestinal differentiation patterns. In both organs, it has been argued that metaplasia may represent a recapitulation of the embryonic or juvenile gastrointestinal tract, as cells access a developmental progenitor genetic program that can help repair damaged tissue. Here, we review the normal development of esophagus and stomach, and describe how BE represents an intermixing of cells resembling gastric pseudopyloric (SPEM) and intestinal metaplasia. We discuss a cellular process recently termed "paligenosis" that governs how mature, differentiated cells can revert to a proliferating progenitor state in metaplasia. We discuss the "Cyclical Hit" theory in which paligenosis might be involved in the increased risk of metaplasia for progression to cancer. However, somatic mutations might occur in proliferative phases and then be warehoused upon redifferentiation. Through years of chronic injury and many rounds of paligenosis and dedifferentiation, eventually a cell with a mutation that prevents dedifferentiation may arise and clonally expand fueling stable metaplasia and potentially thereafter acquiring additional mutations and progressing to dysplasia and cancer.

Modulation of intestinal cell differentiation in growing pigs is dependent on the fiber source in the diet

Feeding high-fiber diets decreases cost, but also caloric and nutritional efficiency by modifying intestinal morphology and function. We analyzed the changes in intestinal cell composition, nutrient transporters and receptors, and cell differentiation induced by fibers from different sources. Forty-six finishing pigs (BW 84 ± 7 kg) were fed 1 of 4 diets: corn-soybean (Control; = 12), 23% wheat straw (WS; = 11), 55% corn distillers dried grains with solubles (DDGS; = 11), and 30% soybean hulls (SBH; = 12). Pigs were fed 2 meals daily to an amount equivalent to 2.5% of initial BW for 14 d in metabolism cages. Ilea were collected for histological and gene expression analysis after euthanasia. Data were analyzed using the Kruskal-Wallis test followed by Dunn's multiple comparisons and differences considered significant when < 0.05. The enterocyte marker was increased ( < 0.03) by feeding SBH compared with Control and WS diets. Goblet cells presence was greater ( < 0.01) in pigs fed WS and DDGS compared with Control, and in pigs fed WS compared with SBH ( = 0.02). expression was greater ( < 0.05) in pigs fed DDGS and SBH compared with Control diet. No changes were observed for endocrine and Paneth cells markers, villus and crypt length, or proliferation index. Compared with the Control, gene expression of receptors for oligopeptides, calcium, glucose, fructose, , and and was increased ( < 0.05) by feeding WS and DDGS diets. Feeding SBH diet repressed ( < 0.005) the compared with WS and DDGS diets, while DDGS repressed ( = 0.02) its expression compared with Control. Pigs fed DDGS had reduced ( < 0.001) , and those fed SBH showed increased ( < 0.05) expression compared with WS and DDGS pigs. Feeding WS and DDGS diets induced ( < 0.01) the expression of stem cell marker r-spondin receptor (, while was reduced ( < 0.02) by feeding DDGS compared with Control. The expression of was induced ( < 0.05) by all fibers compared with Control. Transcription factors and were suppressed ( < 0.001) by WS and DDGS compared with Control. In conclusion, feeding diets containing WS and DDGS modulated intestinal differentiation by promoting goblet cells and altered expression of nutrient receptors and transporters in growing pigs, while feeding SBH had less effect.

[Continual self-renewal of the gastric epithelium by cell differentiation: implications for carcinogenesis]

BACKGROUND

The gastric mucosa and its glands represent a close interactive barrier to the outside world. This delicate surface is protected by a multilayered mucus barrier which contains among others the mucins MUC5AC and MUC6 and the trefoil factor family peptide TFF2. Furthermore, two types of gastric glands form delicate homeostatic systems, i.e. the fundic and antral glands, which show continual bidirectional self-renewal via differentiation from stem and progenitor cells. It was the aim of this study to analyze the self-renewal of these gastric units.

MATERIAL AND METHODS

Three characteristic regions (i.e. foveolar, proliferative zone and lower gland regions) were isolated from fundic and antral units by the use of laser microdissection and expression profiles concerning known marker genes were generated by reverse transcription polymerase chain reaction (RT-PCR) analysis.

RESULTS

The surface mucous cells (SMCs) of fundic and antral units characteristically differed in the expression of certain secretory genes. Furthermore, the maturation of mucous neck cells and their trans-differentiation into chief cells as well as the maturation of antral SMCs and antral gland cells occurred in a stepwise manner.

DISCUSSION

The correct maturation particularly of mucous neck cells and their trans-differentiation into chief cells is critical for homeostatic self-renewal of fundic units. Dysregulation of this multistep process can result in generation of the spasmolytic polypeptide-expressing metaplasia (SPEM) lineage which is characterized by its strong ectopic TFF2 expression. Chronic inflammation is known to support SPEM formation. The SPEM lineage is a precancerous lesion which can further differentiate into intestinal metaplasia.

Helicobacter felis--associated gastric disease in microbiota-restricted mice

Human Helicobacter pylori infection leads to multiple pathological consequences, including gastritis and adenocarcinoma. Although this association has led to the classification of H. pylori as a type 1 carcinogen, it is not clear if additional nonhelicobacter gastric microbiota play a role in these diseases. In this study, we utilized either specific pathogen-free C57BL/6 mice (B6.SPF) or mice colonized with altered Schaedler flora (B6.ASF) to evaluate the role of nonhelicobacter gastric microbiota in disease development after Helicobacter felis infection. Despite similar histological changes, H. felis persisted in B6.ASF stomachs, while H. felis could no longer be detected in the majority of B6.SPF mice. The B6.SPF mice also acquired multiple Lactobacillus spp. in their stomachs after H. felis infection. Our data indicate that potential mechanisms responsible for the ineffective H. felis clearance in the B6.ASF model include the absence of new gastric microbiota to compete for the gastric niche, the lack of expression of new gastric mucins, and a reduced ratio of H. felis-specific IgG2c:IgG1 serum antibodies. These data suggest that although H. felis is sufficient to initiate gastric inflammation and atrophy, bacterial eradication and the systemic immune response to infection are significantly influenced by pre-existing and acquired gastric microbiota.

Regulation of secretory granule size by the precise generation and fusion of unit granules

Morphometric evidence derived from studies of mast cells, pancreatic acinar cells and other cell types supports a model in which the post-Golgi processes that generate mature secretory granules can be resolved into three steps: (1) fusion of small, Golgi-derived progranules to produce immature secretory granules which have a highly constrained volume; (2) transformation of such immature granules into mature secretory granules, a process often associated with a reduction in the maturing granule's volume, as well as changes in the appearance of its content and (3) fusion of secretory granules of the smallest size, termed 'unit granules', forming granules whose volumes are multiples of the unit granule's volume. Mutations which perturb this process can cause significant pathology. For example, Chediak-Higashi syndrome / lysosomal trafficking regulator (CHS)/(Lyst) mutations result in giant secretory granules in a number of cell types in human beings with the Chediak-Higashi syndrome and in 'beige' (Lyst(bg)/Lyst(bg)) mice. Analysis of the secretory granules of mast cells and pancreatic acinar cells in Lyst-deficient beige mice suggests that beige mouse secretory granules retain the ability to fuse randomly with other secretory granules no matter what the size of the fusion partners. By contrast, in normal mice, the pattern of granule-granule fusion occurs exclusively by the addition of unit granules, either to each other or to larger granules. The normal pattern of fusion is termed unit addition and the fusion evident in cells with CHS/Lyst mutations is called random addition. The proposed model of secretory granule formation has several implications. For example, in neurosecretory cells, the secretion of small amounts of cargo in granules constrained to a very narrow size increases the precision of the information conveyed by secretion. By contrast, in pancreatic acinar cells and mast cells, large granules composed of multiple unit granules permit the cells to store large amounts of material without requiring the amount of membrane necessary to package the same amount of cargo into small granules. In addition, the formation of mature secretory granules that are multimers of unit granules provides a mechanism for mixing in large granules the contents of unit granules which differ in their content of cargo.

Is there such a thing as a renal stem cell?

Increasing interest in the potential of adult stem cells in regenerative medicine has led to numerous studies focused on the identification of endogenous renal stem cells within the mature mammalian kidney. A variety of approaches have been taken to identify such cells, including physical location, cell surface marker expression, and functional properties. Proof of clonogenicity or renal potential remains questionable, and few such populations have been characterized in humans; however, recent evidence that even podocytes, a cell type with limited proliferative capacity under normal conditions, are constantly regenerated from a population within the Bowman's capsule has breathed new life into the quest for a renal stem cell. Here we examine whether current evidence is sufficient to conclude such a population does indeed exist or whether the jury is still out. We also ask which properties we would wish such a cell to possess to allow for repair of the diseased kidney.

Cross talk between hedgehog and epithelial-mesenchymal transition pathways in gastric pit cells and in diffuse-type gastric cancers

We previously reported hedgehog (Hh) signal activation in the mucus-secreting pit cell of the stomach and in diffuse-type gastric cancer (GC). Epithelial–mesenchymal transition (EMT) is known to be involved in tumour malignancy. However, little is known about whether and how both signallings cooperatively act in diffuse-type GC. By microarray and reverse transcription–PCR, we investigated the expression of those Hh and EMT signalling molecules in pit cells and in diffuse-type GCs. How both signallings act cooperatively in those cells was also investigated by the treatment of an Hh-signal inhibitor and siRNAs of Hh and EMT transcriptional key regulator genes on a mouse primary culture and on human GC cell lines. Pit cells and diffuse-type GCs co-expressed many Hh and EMT signalling genes. Mesenchymal-related genes (WNT5A, CDH2, PDGFRB, EDNRA, ROBO1, ROR2, and MEF2C) were found to be activated by an EMT regulator, SIP1/ZFHX1B/ZEB2, which was a target of a primary transcriptional regulator GLI1 in Hh signal. Furthermore, we identified two cancer-specific Hh targets, ELK1 and MSX2, which have an essential role in GC cell growth. These findings suggest that the gastric pit cell exhibits mesenchymal-like gene expression, and that diffuse-type GC maintains expression through the Hh–EMT pathway. Our proposed extensive Hh–EMT signal pathway has the potential to an understanding of diffuse-type GC and to the development of new drugs.

Genetic variation in PSCA is associated with susceptibility to diffuse-type gastric cancer

Gastric cancer is classified into intestinal and diffuse types, the latter including a highly malignant form, linitis plastica. A two-stage genome-wide association study (stage 1: 85,576 SNPs on 188 cases and 752 references; stage 2: 2,753 SNPs on 749 cases and 750 controls) in Japan identified a significant association between an intronic SNP (rs2976392) in PSCA (prostate stem cell antigen) and diffuse-type gastric cancer (allele-specific odds ratio (OR) = 1.62, 95% CI = 1.38-1.89, P = 1.11 x 10(-9)). The association was far less significant in intestinal-type gastric cancer. We found that PSCA is expressed in differentiating gastric epithelial cells, has a cell-proliferation inhibition activity in vitro and is frequently silenced in gastric cancer. Substitution of the C allele with the risk allele T at a SNP in the first exon (rs2294008, which has r(2) = 0.995, D' = 0.999 with rs2976392) reduces transcriptional activity of an upstream fragment of the gene. The same risk allele was also significantly associated with diffuse-type gastric cancer in 457 cases and 390 controls in Korea (allele-specific OR = 1.90, 95% CI = 1.56-2.33, P = 8.01 x 10(-11)). The polymorphism of the PSCA gene, which is possibly involved in regulating gastric epithelial-cell proliferation, influences susceptibility to diffuse-type gastric cancer.

Orchestration of dysregulated epithelial turnover by a manipulative pathogen

Chronic Helicobacter pylori infection is the strongest known risk factor for the development of gastric cancer. In order to survive and propagate under the harsh conditions of the gastric niche, this pathogen has evolved numerous means to interact with host epithelium. In this issue, Mimuro et al. shed light on mechanisms by which Helicobacter pylori attenuates apoptosis in the gastric epithelium to facilitate its persistence within the human stomach.

GASDERMIN, suppressed frequently in gastric cancer, is a target of LMO1 in TGF-β-dependent apoptotic signalling

Defining apoptosis-regulatory cascades of the epithelium is important for understanding carcinogenesis, since cancer cells are considered to arise as a result of the collapse of the cascades. We previously reported that a novel gene GASDERMIN (GSDM) is expressed in the stomach but suppressed in gastric cancer cell lines. Furthermore, in this study, we demonstrated that GSDM is expressed in the mucus-secreting pit cells of the gastric epithelium and frequently silenced in primary gastric cancers. We found that GSDM has a highly apoptotic activity and its expression is regulated by a transcription factor LIM domain only 1 (LMO1) through a sequence to which Runt-related transcription factor 3 (RUNX3) binds, in a GSDM promoter region. We observed coexpression of GSDM with LMO1, RUNX3 and type II transforming growth factor-beta receptor (TGF-betaRII) in the pit cells, and found that TGF-beta upregulates the LMO1- and GSDM-expression in the gastric epithelial cell line and induces apoptosis, which was confirmed by the finding that the apoptosis induction is inhibited by suppression of each LMO1-, RUNX3- and GSDM expression, respectively. The present data suggest that TGF-beta, LMO1, possibly RUNX3, and GSDM form a regulatory pathway for directing the pit cells to apoptosis.

Radiation-induced gastric epithelial apoptosis occurs in the proliferative zone and is regulated by p53, bak, bax, and bcl-2

Unlike the small intestine and colon where gamma-radiation-induced apoptosis has previously been well characterized, the response of murine gastric epithelium to gamma-radiation has not been investigated in detail. Apoptosis was therefore assessed on a cell positional basis in gastric antral and corpus glands from adult male mice following gamma-radiation. Maximum numbers of apoptotic cells were observed in both antrum and corpus at 48 h and at radiation doses greater than 12 Gy. However, the number of apoptotic cells observed in the gastric epithelium was much lower than observed in the small intestine or colon after similar doses of radiation. Hematoxylin and eosin, caspase 3 immunohistochemistry, and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling detected similar numbers and cell positional distributions of apoptotic cells, hence hematoxylin and eosin was used for subsequent studies. The highest numbers of apoptotic cells were observed at cell positions 5-6 in the antrum and cell positions 15-18 in the corpus. These distributions coincided with the distributions of PCNA-labeled proliferating cells, but not with the distributions of H(+)-K(+)-ATPase-labeled parietal cells or TFF2-labeled mucous neck cells. Decreased numbers of apoptotic gastric epithelial cells were observed in p53-null, bak-null, and bax-null mice compared with wild-type counterparts 6 and 48 h after 12 Gy gamma-radiation. Significantly increased numbers of apoptotic gastric epithelial cells were observed in bcl-2-null mice compared with wild-type littermates 6 h after 12 Gy gamma-radiation. Radiation therefore induces apoptosis in the proliferative zone of mouse gastric epithelium. This response is regulated by the expression of p53, bak, bax, and bcl-2.

Localization of TFF3 peptide in human esophageal submucosal glands and gastric cardia: differentiation of two types of gastric pit cells along the rostro-caudal axis

TFF3 (trefoil factor family 3), which is a major secretory product of the gastric antrum and the intestine, but which is nearly absent in the gastric corpus, plays a key role in the maintenance of mucosal integrity. Here, we have systematically investigated TFF3 expression in the esophagus and gastric cardia by the use of reverse transcription/polymerase chain reaction (RT-PCR) analysis and immunohistochemistry. Synthesis of TFF3, but not TFF1 or TFF2, is detectable in esophageal submucosal glands. The stratified squamous epithelium is devoid of TFF synthesis. Prominent TFF3 expression starts at the Z-line with a sharply decreasing gradient toward the cardia. Immunohistochemistry has localized TFF3 to surface mucous cells of the proximal cardia. TFF3 distribution differs characteristically from that of TFF1 (secreted primarily by superficial surface mucous cells), whereas TFF3, together with the mucin MUC5AC, is also found in deeper lying cells toward the isthmus. This is the first report of TFF3 as a typical secretory peptide of esophageal submucosal glands and gastric cardia. The different expression patterns of TFF3 and TFF1 in the cardia suggest a stepwise maturation of surface mucous cells from TFF3/MUC5AC-positive cells close to the isthmus to TFF1/TFF3/MUC5AC-positive cells at the pit. The gradient of TFF3 expression along the gastric rostro-caudal axis defines two types of gastric pit cells: those secreting TFF3 in the cardia and the antrum and those nearly devoid of TFF3 synthesis in the corpus. This indicates the special requirement, particularly of the esophagogastric junction, for TFF3-triggered protection and repair.

Gastrin-induced apoptosis contributes to carcinogenesis in the stomach

Hypergastrinemia in INS-GAS mice leads to accelerated carcinogenesis of the stomach, but the mechanisms have not been well defined. We investigated the possible role of gastrin-induced gastric cell apoptosis in the development of gastric cancer. We examined apoptosis and the expression of Bcl-2 family proteins in INS-GAS mice of different ages, as well as in gastrin-deficient (GAS-KO) mice after gastrin-17 (G-17) infusion. In addition, we studied the effects of the gastrin/cholecystokinin-2 (CCK-2) receptor antagonist YF476 and/or histamine H2 (H-2) receptor antagonist loxtidine on apoptosis and atrophy in INS-GAS mice with or without Helicobacter felis (H. felis) infection. INS-GAS mice had age-associated increases in Bax protein expression and decreases in Bcl-2 protein expression, along with increased glandular and epithelial cell apoptosis. At 8-week gastrin infusions in GAS-KO mice resulted in a similar pattern of altered Bax and Bcl-2 expression, followed by gastric cell apoptosis. H. felis infection of INS-GAS mice led to increased apoptosis and the development of atrophy, whereas treatment with either YF476 and/or loxtidine strongly inhibited both apoptosis and atrophy. In vitro studies with Fas-expressing RGM1 cells showed that gastrin stimulation alone directly induced apoptosis via gastrin/CCK-2 receptor and synergized with FasL stimulation. These results indicate that gastrin can induce apoptosis in gastric epithelial cells and contribute to the development of gastric carcinogenesis.

Integrative roles of transforming growth factor-alpha in the cytoprotection mechanisms of gastric mucosal injury

Background

Transforming growth factor α (TGFα) protects against gastric mucosal injury and facilitates wound healing. However, its overexpression is known to induce hypertrophic gastropathy resembling Menetrier's disease in transgenic (TG) mice on an FVB background, as one of the authors reported previously. We studied another TGFα-expressing mouse line on a CD1 background, whose gastric mucosa appears normal. Since this TG mouse had a strong resistance to ethanol-induced gastric injury, we considered the long-term effect of TGFα on several gastric protection mechanisms.

Methods

TGFα-expressing transgenic (TG) mouse lines bearing human TGFα cDNA under the control of the mouse metallothionein gene I promoter were generated on a CD1 mouse background, and analyzed their ethanol injury-resistant phenotypes produced by TGFα.

Results

In the TG mucosa, blood flow was well maintained after ethanol injury. Further, neural and inducible types of NO synthases were consistently and widely expressed in the TG mucosa, compared with the limited distribution of neural type NO synthase in the luminal pit region of the wild-type (WT) mucosa. COX-2 and its upstream transcription factor NfkB were constitutively elevated in the TG mucosa even before ethanol administration, whereas they were induced in the same region of the WT mucosa only after ethanol injury. Two anti-apoptotic proteins, HSP70 and Bcl-2, were upregulated in the TG mucosa even before ethanol administration, while they were not expressed in the WT mucosa before the injury. Furthermore, pro-caspase 3 activation was inhibited in the TG mucosa, while it was converted to the active form in the WT mucosa following ethanol administration.

Conclusion

We conclude that TGFα maintains the gastric mucosal defense against gastric injury by integrating other cytoprotective mechanisms.

Discovery of aberrant expression of R-RAS by cancer-linked DNA hypomethylation in gastric cancer using microarrays

Although hypomethylation was the originally identified epigenetic change in cancer, it was overlooked for many years in preference to hypermethylation. Recently, gene activation by cancer-linked hypomethylation has been rediscovered. However, in gastric cancer, genome-wide screening of the activated genes has not been found. By using microarrays, we identified 1,383 gene candidates reactivated in at least one cell line of eight gastric cancer cell lines after treatment with 5-aza-2'deoxycytidine and trichostatin A. Of the 1,383 genes, 159 genes, including oncogenes ELK1, FRAT2, R-RAS, RHOB, and RHO6, were further selected as gene candidates that are silenced by DNA methylation in normal stomach mucosa but are activated by DNA demethylation in a subset of gastric cancers. Next, we showed that demethylation of specific CpG sites within the first intron of R-RAS causes activation in more than half of gastric cancers. Introduction of siRNA into R-RAS-expressing cells resulted in the disappearance of the adhered cells, suggesting that functional blocking of the R-RAS-signaling pathway has great potential for gastric cancer therapy. Our extensive gene list provides other candidates for this class of oncogene.

Induction of DMBT1 expression by reduced ERK activity during a gastric mucosa differentiation-like process and its association with human gastric cancer

Abnormalities in the expression of DMBT1 (deleted in malignant brain tumors 1) have been implicated in the development of esophageal, gastric and colorectal cancers of the alimentary tract, but the underlying mechanism remains unclear. In the present study, using the gastric cell line AGS, we identified two intracellular signaling molecules protein kinase C (PKC) and extracellular signal-related kinase (ERK). They mediated both the phorbol myristate acetate (PMA) downregulation of DMBT1 expression and the initiation of cell differentiation, which was measured by cell cycle withdrawal and the induction of the tissue-specific marker trefoil factor 1 (TFF1). A time-course study showed that following the PMA activation of ERK kinase, the induction of TFF1 and the reduction of DMBT1 were detected at the same time point. We then demonstrated a minimal level of DMBT1 in proliferating AGS cells seeded at low density, where ERK activity was high. Reduction of ERK activity, either by an ERK inhibitor PD98059 or by high-density seeding, significantly reduced AGS cell growth judged by CFSE labeling. This cellular effect was elicited by cyclin D/p21 (Cip/Waf1) and G(0)/G(1) arrest, and was accompanied by a marked increase in DMBT1-expressing cells. Finally, we showed that siRNA directed against DMBT1 had no effect on the induction of a cell growth arrest marker, gut-enriched Kruppel-like factor (GKLF), but reduced the PMA induction of TFF1. Along with its upregulation coinciding with G(0)/G(1) arrest, and its attenuation in differentiated cells, these results suggest that the transient induction of DMBT1 is apparently specific at an early stage of gastric epithelial differentiation-like process, when it may play a role in cell fate decision. Consistent with such a potential function, we detected frequent abnormalities of the DMBT1 expression in the specimens of human gastric adenocarcinoma.

Unique roles of G protein-coupled histamine H2 and gastrin receptors in growth and differentiation of gastric mucosa

Disruption of histamine H2 receptor and gastrin receptor had different effects growth of gastric mucosa: hypertrophy and atrophy, respectively. To clarify the roles of gastrin and histamine H2 receptors in gastric mucosa, mice deficient in both (double-null mice) were generated and analyzed. Double-null mice exhibited atrophy of gastric mucosae, marked hypergastrinemia and higher gastric pH than gastrin receptor-null mice, which were unresponsive even to carbachol. Comparison of gastric mucosae from 10-week-old wild-type, histamine H2 receptor-null, gastrin receptor-null and double-null mice revealed unique roles of these receptors in gastric mucosal homeostasis. While small parietal cells and increases in the number and mucin contents of mucous neck cells were secondary to impaired acid production, the histamine H2 receptor was responsible for chief cell maturation in terms of pepsinogen expression and type III mucin. In double-null and gastrin receptor-null mice, despite gastric mucosal atrophy, surface mucous cells were significantly increased, in contrast to gastrin-null mice. Thus, it is conceivable that gastrin-gene product(s) other than gastrin-17, in the stimulated state, may exert proliferative actions on surface mucous cells independently of the histamine H2 receptor. These findings provide evidence that different G-protein coupled-receptors affect differentiation into different cell lineages derived from common stem cells in gastric mucosa.

The "normal" endocrine cell of the gut: changing concepts and new evidences

The endocrine cells of the gut are a highly specialized mucosal cell subpopulation. Within the gastrointestinal tract at least 14 different cell types produce a wide range of hormones with a specific regional distribution. The gut endocrine cells belong to the diffuse endocrine system. These cells present two regulated pathways of secretion characterized by large dense core vesicles (LDCV) and synaptic-like microvesicles (SLMV). Gut endocrine cells are recognized by the expression of several "general" markers, including the LDCV marker chromogranin A and the SLMV marker synaptophysin, in addition to the cytosolic markers neuron-specific enolase and protein gene product 9.5. The expression of different hormones identifies specific cell types. The gut endocrine cells are reputed to be terminally differentiated and incapable of proliferation. However, some data suggest that the number of gut endocrine cells may adapt in response to tissue-specific physiological stimuli. Gut endocrine cell differentiation appears to follow a "constitutive" tissue-specific pathway, which may be disrupted and investigated by genetic manipulation in mice. It is suggested that endocrine cell homeostasis is maintained by the entry of new endocrine-committed cells along the differentiation pathway and that such intermediate cells may be sensitive to physiological stimuli as well as transforming agents.

Insights into the regulation of gastric acid secretion through analysis of genetically engineered mice

The regulation of acid secretion in the stomach involves a complex network of factors that stimulate secretion in response to the ingestion of a meal and maintain homeostasis of gastric pH. Genetically engineered mouse models have provided a new opportunity to investigate the importance and function of specific molecules and pathways involved in the regulation of acid secretion. Mouse mutants with disruptions in the three major stimulatory pathways for acid secretion in parietal cells, gastrin, histamine, and acetylcholine, have been generated. Disruption of the gastrin pathway results in a major impairment in both basal and induced acid secretion. Histamine and acetylcholine pathway mutants also have significant alterations in acid secretion, although the impairment does not appear to be as severe as in gastrin pathway mutants, perhaps due in part to the hypergastrinemia that occurs. Mice with a disruption in the somatostatin pathway have increased gastric acid secretion, which confirms an important negative regulatory role for this factor. This review discusses these genetically engineered mouse models, as well as others, that provide insight into the complex regulation of in vivo gastric acid secretion. The regulation of growth and cellular morphology of the stomach in these mouse models is also presented. In addition, transgene promoters that are expressed in the gastric epithelium are discussed because these promoters will be important tools to alter cellular physiology in new mouse models in the future.

Structural and functional characterization of gastric mucosa and central nervous system in histamine H2 receptor-null mice

To examine the physiological role of the histamine H(2) receptor, histamine H(2) receptor-null mice were generated by homologous recombination. Histamine H(2) receptor-null mice, which developed normally and were fertile and healthy into adulthood, exhibited markedly enlarged stomachs and marked hypergastrinemia. The former was due to hyperplasia of gastric gland cells (small-sized parietal cells, enterochromaffin-like cells and mucous neck cells which were rich in mucin), but not of gastric surface mucous cells, which were not increased in number as compared with those in wild-type mice despite the marked hypergastrinemia. Basal gastric pH was slightly but significantly higher in histamine H(2) receptor-null mice. Although carbachol but not gastrin induced in vivo gastric acid production in histamine H(2) receptor-null mice, gastric pH was elevated by both muscarinic M(3) and gastrin antagonists. Thus, both gastrin and muscarinic receptors appear to be directly involved in maintaining gastric pH in histamine H(2) receptor-null mice. Interestingly, gastric glands from wild-type mice treated with an extremely high dose of subcutaneous lansoprazole (10 mg/kg body weight) for 3 months were very similar to those from histamine H(2) receptor-null mice. Except for hyperplasia of gastric surface mucous cells, the findings for gastric glands from lansoprazole-treated wild-type mice were almost identical to those from gastric glands from histamine H(2) receptor-null mice. Therefore, it is possible that the abnormal gastric glands in histamine H(2) receptor-null mice are secondary to the severe impairment of gastric acid production, induced by the histamine H(2) receptor disruption causing marked hypergastrinemia. Analyses of the central nervous system (CNS) of histamine H(2) receptor-null mice revealed these mice to be different from wild-type mice in terms of spontaneous locomotor activity and higher thresholds for electrically induced convulsions. Taken together, these results suggest that (1) gastrin receptors are functional in parietal cells in histamine H(2) receptor-null mice, (2) abnormal gastric glands in histamine H(2) receptor-null mice may be secondary to severe impairment of gastric acid production and secretion and (3) histamine H(2) receptors are functional in the central nervous system.

A model for integrative study of human gastric acid secretion

We have developed a unique virtual human model of gastric acid secretion and its regulation in which food provides a driving force. Food stimulus triggers neural activity in central and enteric nervous systems and G cells to release gastrin, a critical stimulatory hormone. Gastrin stimulates enterochromaffin-like cells to release histamine, which, together with acetylcholine, stimulates acid secretion from parietal cells. Secretion of somatostatin from antral and corpus D cells comprises a negative-feedback loop. We demonstrate that although acid levels are most sensitive to food and nervous system inputs, somatostatin-associated interactions are also important in governing acidity. The importance of gastrin in acid secretion is greatest at the level of transport between the antral and corpus regions. Our model can be applied to study conditions that are not yet experimentally reproducible. For example, we are able to preferentially deplete antral or corpus somatostatin. Depletion of antral somatostatin exhibits a more significant elevation of acid release than depletion of corpus somatostatin. This increase in acid release is likely due to elevated gastrin levels. Prolonged hypergastrinemia has significant effects in the long term (5 days) by promoting enterochromaffin-like cell overgrowth. Our results may be useful in the design of therapeutic strategies for acid secretory dysfunctions such as hyper- and hypochlorhydria.

Gastrin interferes with the differentiation of gastric pit cells and parietal cells

BACKGROUND

Gastrin is known to have stimulatory effects on gastric mucosa; however, long-term effect of gastrin stimulation is not well known.

AIM AND METHODS

To investigate the long-term effect of hypergastrinaemia, we established hypergastrinaemic transgenic mice by introducing a mutated human gastrin gene. Homozygously transgene-expressing mice showed serum gastrin levels of more than 600 pg/mL.

RESULTS

Neither progastrin nor glycine-extended gastrin titre elevation were observed in hypergastrinaemic transgenic mice. Stomachs from the 30-35-week-old transgenic mice were 30-50% heavier and their mucosa were markedly thicker than those of the controls. The hypertrophic gastric mucosa of hypergastrinaemic transgenic mice consisted of elongated pits with widespread proliferative zones, and comprised depleted glandular regions. In situ hybridization study indicated that expression of H, K-ATPase mRNA in parietal cells of hypergastrinaemic transgenic mice was markedly decreased. By gastrin binding assay in vivo, specific gastrin binding sites were observed in the mid-glandular region of hypergastrinaemic transgenic mice that consisted mainly of prepit cells.

CONCLUSIONS

These results suggest that long-term stimulation of gastrin increases the expression of CCK-B/gastrin receptors in the less-differentiated pit cells that are the main component of elongated gastric units, and lessens the well-differentiated characteristics of parietal cells.

Gastrin stimulates the growth of gastric pit cell precursors by inducing its own receptors

Gastrin/CCK-B receptors (CCKB-Rs) are present on parietal and enterochromaffin-like cells in the gastric mucosa but not on pit cells in the proliferative zone. Because serum gastrin levels are well correlated with the growth of the gastric pit, we examined whether pit precursor cells express CCKB-Rs using hypergastrinemic transgenic mice and a mouse pit precursor cell line, GSM06. In situ hybridization indicated that CCKB-R mRNA was limited to the lower one-third of the mucosa in control mice, whereas it was faintly distributed along the mid- to low glandular region in the hypergastrinemic transgenic mouse mucosa. CCKB-R-positive midglandular cells appear to have a pit cell lineage; therefore, GSM06 cells were used for an [(125)I]gastrin binding study. [(125)I]gastrin bound to the membrane fraction of the GSM06 cells when precultured with gastrin. Gastrin dose dependently induced CCKB-R expression in GSM06 cells and stimulated their growth. Thus these findings suggest that gastrin directly stimulates the growth of the pit cell lineage by inducing its own receptor in pit cell precursors.

Pathophysiology of abomasal parasitism: is the host or parasite responsible?

Nematode larvae developing within the glands cause local loss of parietal cells and mucous cell hyperplasia whereas reduced acid secretion, increased serum gastrin and pepsinogen concentrations and generalized histological changes are associated with parasites in the abomasal lumen. Parietal cells with dilated canaliculi and/or degenerative changes typical of necrosis are present soon after the transplantation of adult worms, and abomasal secretion is also affected. Anaerobic bacteria survive in greater numbers as the pH rises, with bacterial densities becoming similar to ruminal populations at an abomasal pH of 4 and above. Failure to lyse bacteria may affect adversely the nutrition of the host. The parasites may initiate the pathophysiology through the release of excretory/secretory (ES) products which either act directly on parietal cells or indirectly through enterochromaffin-like (ECL) cells by provoking inflammation or by disrupting the protective mucosal defence system. Parietal cell dysfunction is proposed as a key event which leads to loss of mature chief cells and mucous cell hyperplasia, as well as hypergastrinaemia. Inflammation increases circulating pepsinogen concentrations and may also contribute to increased gastrin secretion. Stimulation of mucosal proliferation and differentiation of parietal cells in the isthmus by the raised serum gastrin levels will be beneficial by generating a new population of active parietal cells and adequate acid secretion.

PRL-1 PTPase expression is developmentally regulated with tissue-specific patterns in epithelial tissues

The mechanisms controlling tyrosine phosphorylation of cellular proteins are important in the regulation of many cellular processes, including development and differentiation. Protein tyrosine phosphatases (PTPases) may be as important as protein tyrosine kinases (PTKs) in these processes. PRL-1 is a distinct PTPase originally identified as an immediate-early gene in liver regeneration whose expression is associated with growth in some tissues but with differentiation in others. We now demonstrate that the PRL-1 protein is expressed during development in a number of digestive epithelial tissues. It is expressed at variable time points in the developing intestine, but its expression is limited to the developing villus enterocytes. In the gastric epithelium, PRL-1 expression in the adult is restricted to zymogen cells. PRL-1 is also expressed in the developing liver and esophagus and in the epithelia of the kidney and lung. In each of these contexts, the expression of PRL-1 is associated with terminal differentiation, suggesting that it may play a role in this important developmental process.

Gastrin stimulates the growth of gastric pit with less-differentiated features

Gastrin stimulates the growth of gastric mucosa by increasing mostly its glandular region but is not known to induce the growth of a pit region where its major constituent cells, gastric surface mucous (GSM) cells, turn over rapidly. To investigate the effect of gastrin on GSM cells, we generated hypergastrinemic mice by expressing a human gastrin transgene. We obtained a hypergastrinemic mouse line whose average serum gastrin level is 671 +/- 252 pg/ml (normal level <150 pg/ml). Gastrin-positive cells were found in the fundic mucosa. The gastric mucosa exhibited hypertrophic growth, which was characterized by an elongated pit with an active proliferative zone, but the glandular region containing parietal cells was normal or reduced in size. The GSM cells contained fewer mucous granules than those of control littermates and lost reactivity to the GSM cell-specific cholera toxin beta-subunit lectin. GSM cells along the foveolar region and many mucous neck cells became Alcian blue positive, suggesting the appearance of sialomucin in these cells. We suggest that gastrin stimulates the growth of the proliferative zone of gastric glands, which results in the elongation of the pit region whose GSM cells exhibit less-differentiated features.

Lessons from genetically engineered animal models. III. Lessons learned from gastrin gene deletion in mice

Gastrin is the principal hormonal inducer of gastric acid secretion. Chronic hypergastrinemia, leading to hypersecretion of gastric acid and increased proliferation of parietal and enterochromaffin-like (ECL) cells, has been well described. In contrast, the physiological consequences of chronic gastrin deficiency had been poorly understood until the recent genetic engineering of mouse mutants containing a gastrin gene deletion by homologous recombination in embryonic stem cells. This themes article describes the consequences of constitutive gastrin deficiency on the development and physiology of the stomach. A lack of gastrin disrupts basal gastric acid secretion and renders the acid secretory system unresponsive to acute histaminergic, cholinergic, and gastrinergic stimulation. The defect in acid secretion is greater than would have been predicted from previous studies in which gastrin action was acutely blocked. Cellular changes include thinning of the gastric mucosa in the gastrin-deficient mice, with a reduction in parietal cells and reduced expression of markers of parietal and ECL cell-differentiated functions. The results suggest that gastrin is required for the functional maturation of the acid-secretory system.

Development of the human gastrointestinal tract: twenty years of progress

A combination of approaches has begun to elucidate the mechanisms of gastrointestinal development. This review describes progress over the last 20 years in understanding human gastrointestinal development, including data from both human and experimental animal studies that address molecular mechanisms. Rapid progress is being made in the identification of genes regulating gastrointestinal development. Genes directing initial formation of the endoderm as well as organ-specific patterning are beginning to be identified. Signaling pathways regulating the overall right-left asymmetry of the gastrointestinal tract and epithelial-mesenchymal interactions are being clarified. In searching for extrinsic developmental regulators, numerous candidate trophic factors have been proposed, but compelling evidence remains elusive. A critical gene that initiates pancreas development has been identified, as well as a number of genes regulating liver, stomach, and intestinal development. Mutations in genes affecting neural crest cell migration have been shown to give rise to Hirschsprung's disease. Considerable progress has been achieved in understanding specific phenomena, such as the transcription factors regulating expression of sucrase-isomaltase and fatty acid-binding protein. The challenge for the future is to integrate these data into a more complete understanding of the physiology of gastrointestinal development.

Impaired gastric acid secretion in gastrin-deficient mice

To further understand the role of the peptide hormone gastrin in the development and function of the stomach, we have generated gastrin-deficient mice by gene targeting in embryonic stem cells. Mutant mice were viable and fertile, without obvious visible abnormalities. However, gastric function was severely affected by the loss of gastrin. Basal gastric acid secretion was abolished and could not be induced by histamine, carbachol, or gastrin. Histological analysis revealed alterations in the two cell types primarily involved in acid secretion, parietal and enterochromaffin-like (ECL) cells. Parietal cells were reduced in number with an accumulation of immature cells lacking H(+)-K(+)-adenosinetriphosphatase (H(+)-K(+)-ATPase). ECL cells were positioned closer to the base of the gastric glands, with markedly lower expression of histidine decarboxylase. Gastrin administration for 6 days reversed the effects of the gastrin deficiency, leading to an increase in the number of mature, H(+)-K(+)-ATPase-positive parietal cells and a partial restoration of acid secretion. The results show that gastrin is critically important for the function of the acid secretory system.

Course of apoptotic changes in the rat gastric mucosa caused by oral administration of fusarenon-X

Male 5-week-old Wistar rats orally (po) administered with fusarenon-X (FX) 1.5 mg/kg and control rats po-treated with distilled water were sacrificed at 0-48 hr after gavage. FX-administered rats showed significant dilatation of the stomach with increased fluid contents at 1-24 hr postadministration (PA). Histopathologically, karyopyknosis of chief cells in the basal region of the gastric glands began to appear at 1 hr, and nuclear fragments were seen in the neck cell region at 1.5 hr PA. At 2-4 hr PA, apoptotic cells appeared diffusely in the neck region and focally in the basal region. Electron microscopy revealed that cells phagocytosing apoptotic bodies were the surface epithelia, undifferentiated neck cells, parietal cells and chief cells. No evidence was detected to show that parietal cells underwent apoptotic changes. The apoptotic lesions peaked at 4-6 hr PA, gradually subsided at 12 hr PA, and became minimal leaving apoptotic remnants in the basal region at 24 hr PA. At 48 hr PA, however, diffuse apoptotic lesions reappeared in the basal region at a level similar to that at 2-3 hr PA. This might be attributable to absorption of FX retaining in the stomach for 24 hr. In situ detection of DNA breaks by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) reaction was consistent with the histopathologic findings. Agarose gel electrophoresis of DNA fragments isolated from the gastric mucosae of FX-administered rats showed a ladder pattern after 1.5 hr PA and the pattern became more distinct at 2-4 hr PA.

Proliferation and differentiation of cells from explants of fetal rat stomach

The current understanding of the mechanisms controlling the proliferation and differentiation of the stem cells of the gastric oxyntic glands is limited. The aim of the present study was to develop a method for investigating proliferation and differentiation of undifferentiated cells from fetal rat stomach. Outgrowth of cells was initiated from explants of 16-day-old fetal rat stomachs. At this stage of the fetal development the gastric epithelial cells are undifferentiated. The explants were cultured in DMEM/F-12 medium supplemented with fetal calf serum only, or fetal calf serum combined with either hydrocortisone or pentagastrin. Morphological characterization by means of light microscopy, dye staining and immunostaining was used to identify the growing cells. Both hydrocortisone and pentagastrin accelerated the differentiation towards H,K-ATPase-positive cells, mucus-producing cells and other epithelial cells. H,K-ATPase-positive cells, which were identified by immunostaining with a monoclonal antibody reacting with the alpha-subunit of the H,K-ATPase, grew on top of the confluent layer of epithelioid and fibroblastoid cells. With this method in vitro investigations of the mechanisms of proliferation and differentiation of gastric mucosal cells are possible. Although by different mechanisms, both hydrocortisone and pentagastrin appear to play a regulatory role in these processes.

Differential expression of extracellular matrix components during the morphogenesis of human gastric mucosa

BACKGROUND

Components of extracellular matrix play a crucial role in morphogenesis and epithelial cell differentiation. In this study, we examined the spatiotemporal expression and distribution of several major extracellular macromolecules of developing and adult human gastric mucosa, with particular emphasis on the pit-gland axis.

METHODS

Indirect immunofluorescence was performed on cryosections of developing and adult gastric tissues by using specific antibodies.

RESULTS

From 8 weeks of gestation onward, including adults, heparan sulfate proteoglycan, type IV collagen, and laminin alpha 1, beta 1, and gamma 1 chains were systematically and uniformly located at the basement membrane of the stratified epithelium (8-11 weeks) and of surface and pit-gland epithelia. Between 8 and 20 weeks of gestation, fibronectin and tenascin were colocalized throughout the entire mesenchyme. In adult mucosa, fibronectin was distributed at all levels of surface and glandular epithelium, whereas tenascin expression was restricted to surface and pit epithelial cells. The expression of the alpha 2 laminin chain was first detected at 12 weeks at the base of forming gastric glands. In the adult, the alpha 2 as opposed to the alpha 1 chain of laminin was confined to the basement membrane of the glandular and lower part of gastric pit epithelia.

CONCLUSIONS

This analysis of the composition of the extracellular matrix in human gastric mucosa suggests an important role for some of its components in morphogenesis and maintenance of gastric glands.