Self-renewal of the human gastric epithelium: new insights from expression profiling using laser microdissection.

The gastric mucosa is subject to continual bidirectional renewal by differentiation from stem and transit amplifying cells. It was the aim of this study to characterize the self-renewal of the human gastric mucosa and its two major types of glands in the fundus and antrum, respectively. Three characteristic regions (pit, proliferative, and lower neck regions) were isolated from fundic and antral units by the use of laser microdissection, and expression profiles concerning 15 marker genes were generated by RT-PCR analysis. The surface mucous cells (SMCs) of fundic and antral units differed in their expression of at least four secretory genes, i.e., gastric lipase, TFF3, FCGBP, and lysozyme. The maturation of mucous neck cells was shown to occur stepwise, first towards a mucous phenotype followed by a serous differentiation step. Also, a stepwise maturation of both the antral SMCs and antral gland cells was observed. Additionally, the presence of gastric lipase was also demonstrated for the first time in antral gland cells. In conclusion, the different expression profiles of SMCs of the fundic and antral units could be the basis for the different self-renewal rates of fundic and antral SMCs and could influence the spatial organization of the bacterial microbiota within the various parts of the gastric mucosa.

Co-culture of human gastric endoscopic biopsies with Helicobacter pylori: a simple method for studying early phases of bacteria-host interaction.

Gastric biopsies obtained through endoscopy from patients uninfected by Helicobacter pylori were co-cultured with an H. pylori strain. According to tissue and H. pylori viability, interleukin 8 was increased in biopsy homogenate and supernatant after 12-36h culture. This simple method is suitable to investigate early phases of bacteria-host interaction.

Expression of a candidate marker for progenitor cells, Musashi-1, in the proliferative regions of human antrum and its decreased expression in intestinal metaplasia.

AIM: Reliable makers for progenitor cells in the human stomach have not been elucidated. The aim of the present study was to clarify whether Musashi-1 (Msi-1), which has recently been proposed as a stem cell marker in mouse intestine, serves as a marker for progenitor cells in human stomach. METHODS AND RESULTS: Immunohistochemistry revealed that Msi-1+ cells were detected especially in the isthmus/neck region (the putative position of stem cells) of the adult antrum, but were limited to the basal regions of fetal pyloric glands during the early stages of development. These results suggest that Msi-1 expression occurs specifically in the stem cell-containing regions. Msi-1+ cells were intermingled with proliferating cell nuclear antigen (PCNA)+ cells in the isthmus/neck region of the adult antrum, but did not coexpress PCNA or Ki 67. Msi-1 expression overlapped partly with expression of MUC 5 AC and MUC 6, indicating that Msi-1+ cells retain some features of both foveolar and pyloric gland cell differentiation phenotypes. In contrast, Msi-1 expression in gastric glands showing intestinal metaplasia (IM) became weaker than that in the glands without IM. CONCLUSION: The specific expression of Msi-1 within the proliferative regions suggests that Msi-1 is a marker of cells with progenitor characteristics before active proliferation in human antrum.

Access to intracellular calcium during development in the feline gastric antrum.

Circular smooth muscle cells from the feline newborn antrum, unlike the adult, are unable to respond to myogenic agonists in the absence of extracellular calcium or to exogenous inositol 1,4,5-trisphosphate (IP3). This study examined the reasons behind the relative inaccessibility of intracellular calcium stores in the newborn period. IP3 binding was determined in antral smooth muscle homogenates from adult cats and newborns by evaluating the competitive binding of D-myo-[3H]IP3 and unlabeled IP3. Receptor density (Bmax) (fmol/mg of protein) and binding affinity (Kd) were determined. The Kd was similar in adults (31 +/- 4 nM) and newborns (28 +/- 7 nM); however, the Bmax was markedly decreased in the newborn (647 +/- 181.0 fmol/mg) compared with the adult (1755 +/- 275 fmol/mg). In adult and newborn antral cells, thapsigargin, which causes a net release of Ca2+ from intracellular stores by inhibiting Ca(2+)-ATPase-dependent reuptake activity, caused an early contraction at 30 s that was maintained for at least 20 min. We conclude that, in the newborn, dynamic intracellular calcium stores are present in the smooth muscle of the feline antrum and that differences in accessibility of intracellular calcium stores may be related to changes in the release of calcium from IP3-sensitive stores.

Characterization of actin and myosin in the developing stomach.

During growth and development, dietary intake changes from being predominantly liquid in the newborn period to mixed solid liquid meals. These alterations in diet vary the functional demands placed on the stomach. It has been shown that, during development, smooth muscle of the stomach undergoes changes in the mechanism responsible for the contractile process. In this study, we have investigated the possibility that there are structural changes in two of the major proteins that are responsible for generation of force during smooth muscle contraction: actin and myosin. Actin and myosin were identified in newborn kittens (1 wk old) and adult gastric smooth muscle using one-dimensional SDS-PAGE. Although both the antrum and fundus of the kitten have significantly smaller total amounts of actin and myosin per mg protein than the adult, the ratio of actin to myosin is not significantly different between the age groups. Two different myosin heavy chain (MHC) isoforms, MHC1 (205 kD) and MHC2 (200 kD), were identified in all tissues. The relative amount of MHC1 remained constant during maturation of the stomach. We observed an increase in the amount of MHC2 in the adult, which resulted in a decreased ratio of MHC1 to MHC2 in the adult. We postulate that the decreased quantity of actin and myosin in the kitten stomach and the observed changes in the ratio of the MHC isoforms are related to changes in the gastric motor that occur during growth and development.

Maturation of antroduodenal motor activity in preterm and term infants.

Previous studies have shown that duodenal motility patterns differ in preterm and term infants, but antral motor activities were not compared. Using a validated, low-compliance, continuous-perfusion, neonatal manometric system, antral and duodenal motility was studied in 19 preterm and nine term infants. Antral motility consisted of isolated single contractions and clustered phasic contractions in term and preterm infants. There were no differences in the occurrence or amplitude of antral activity between the two groups of infants. Thus, there was no change of antral motor activity with advancing gestational age. As has been shown in other previous studies, however, intestinal motor characteristics were more immature in preterm than term infants; clustered phasic contractions occurred more frequently (P less than 0.02) and were of shorter duration (P less than 0.02) and lower amplitude (P less than 0.005). Duodenal clusters were significantly less common, while their amplitudes were significantly increased with increasing gestational age. The proportion of antral clusters that were temporally associated with duodenal activity was significantly lower in preterm infants than in term infants (P less than 0.001). Moreover, the degree of association of antral and duodenal activity increased significantly with gestational age (r = 0.5, P = 0.006). These data show that fasting antral motor activity per se is comparable in preterm and term infants; they also suggest that the temporal association of antral and duodenal activity develops in association with progressive changes in duodenal motor activity in the preterm infant.

Development of gastric antral smooth muscle contractility in newborn rabbits.

Muscle strips from newborn and adult rabbits were stimulated with acetylcholine (ACh; receptor activation), potassium (membrane depolarization), and calcium (skinned muscle preparation). The study was designed to determine whether postnatal development is associated with agonist-specific increases in force development or with an overall increase in antral smooth muscle contractility. The results can be summarized as follows. 1) Antral smooth muscle from newborn animals developed less active force than tissues from adult animals when stimulated with ACh. 2) Antral smooth muscle from newborn animals developed less active force than tissues from adult animals when stimulated with potassium. 3) Skinned muscle preparations from newborn animals developed less active force than skinned muscle fibers from adult animals when stimulated with calcium. The data suggest that the overall contractility of antral smooth muscle from the newborn is less than that of the adult and that the difference can be attributed, at least in part, to factors past the level of the membrane. The study does not rule out the possibility that differences might also exist with respect to the availability or mobilization of calcium.

Progastrin maturation during ontogenesis. Accumulation of glycine-extended gastrins in rat antrum at weaning.

The post-translational maturation of antral progastrin was studied in the developing rat. While N-terminal proteolysis remained unchanged and tyrosine O-sulphation varied only slightly during ontogenesis, major changes were observed in the degree of alpha-carboxyamidation. In the third week of life the immediate precursor of amidated gastrin, glycine-extended gastrin, accumulated, and at weaning (day 21) the concentrations exceeded those of amidated gastrin. Our results confirm that weaning is accompanied by an increased synthesis of gastrin and imply that alpha-carboxyamidation is the rate-limiting step during the biosynthetic maturation of gastrin.

Gastrin: levels and trophic action during advancing age.

Changes in antral and serum gastrin levels as well as gastrin (G) and somatostatin (D) cell density were examined in 4- to 16-mo-old Fischer-344 rats. In these rats, the responsiveness of the gastric mucosa to the trophic action of gastrin was also examined. It was observed that whereas serum gastrin levels declined steadily between 4 and 16 mo of age, antral gastrin levels rose sharply during this period. In the antrum of 16-mo-old rats, the density of G-cells, but not D-cells, was found to be lower than in their 4-mo-old counterparts. Thus, when D- to G-cell ratios were calculated, 16-mo-old rats revealed a 50% higher D- to G-cell ratio than the 4-mo-old animals. To assess the trophic action of gastrin, groups of 4-, 8-, and 16-mo-old rats were infused subcutaneously (osmotic minipump) with either saline or gastrin (G-17-I; 250 ng.kg-1.h-1) for 14 days. The gastric mucosa was assayed for thymidine kinase (an indicator of proliferative activity) and DNA and protein content. In the saline-infused rats, gastric mucosal thymidine kinase activity increased sharply between 4 and 16 mo of age without significantly affecting DNA or protein content (expressed as milligrams per 100 g of body weight), suggesting that the age-associated rise in proliferative activity is not accompanied by increased mucosal growth.(ABSTRACT TRUNCATED AT 250 WORDS)

Does corticosterone affect gastric mucosal cell growth during development?

The effect of corticosterone on the growth of the gastric mucosa was investigated during development. The weight of the mucosa and DNA, RNA, and protein content were used as parameters of growth. The pepsinogen content of the oxyntic gland was examined as an indicator of the biological action of corticosterone on development. Corticosterone-treated animals had lower body weights than control animals on days 10-20. This difference was not seen on day 25. Corticosterone administration during the first and second postnatal weeks induced the precocious appearance of pepsinogen in the oxyntic gland mucosa and increased basal acid output. These effects disappeared by day 25. The weight of the mucosa and DNA, RNA, and protein content of the oxyntic gland and antrum increased with age, but corticosterone had no effect on any of these parameters. We conclude that the induction of precocious development of the gastric mucosa by corticosterone is not due to the stimulation of growth.

Immunohistochemical studies on the ontogenesis of some endocrine cells in the chicken antrum and duodenum.

The time of appearance, morphology and topographic distribution of gastrin/CCK-, somatostatin-, 5HT-, and bombesin-like immunoreactive cells during embryonic and postnatal development were studied in chicken antrum and duodenum with immunohistochemical methods. Gastrin/CCK-like cells appeared on or about the 11th day in the antrum and duodenum, somatostatin-like cells around the 12th day in the antrum and the 11th day in the duodenum, bombesin-like cells appeared only in the antrum and only at hatching. In the early stages of development all the immunoreactive cells were localized in the surface epithelium, descending deeper into the glands as these form, although some cells could always be seen in the surface epithelium. Around the 17th day the number of gastrin/CCK-like cells and somatostatin-like cells in the antrum increases, while 5HT-like already become more numerous in the duodenum from the 13th day onwards. Two territories were recognized in the antrum of the adult: the first was near the duodenum where gastrin/CCK-like and somatostatin-like cells, often in close contact, were very numerous; the other territory was near the gizzard where bombesin-like cells were more numerous. Both regions contained 5HT-like cells in smaller number. In adult duodenum, 5HT-like cells were the most numerous, while somatostatin-like cells and gastrin/CCK-like cells, found in more superficial locations, were more scanty.