Expression pattern and cellular localization of pepsinogen in early development and induced by different diets in the spotted knifejaw (Oplegnathus punctatus)

To solve the high mortality rate of early-stage larval feed conversion during aquaculture in Oplegnathus punctatus, the investigation of the structural and functional characteristics of the gastric tissue was conducted. Histological results showed that the gastric gland rudiment appeared at 17 dph. The basic structure of the stomach was fully developed between 26 and 35 dph. Two pepsinogen genes, named OpPGA1 and OpPGA2, were identified in the spotted knifejaw genome. qPCR results of developmental period showed that the two genes were low in expression during early development (5 and 15 dph). At 20 dph, the two genes started to show trace expression, and at 30 dph the mRNA expression levels of OpPGA1 and OpPGA2 reached the highest levels. Results of pepsin activity detection during the development period showed lower activity was detected 22 dph, followed by a peak at 30 dph. Under different feeding inductions, OpPGA1 showed the highest expression in the basic diet group and hard-shell group, while the expression level in the phytophagous group remained consistently low. The mRNA expression level of OpPGA2 in the phytophagous group was significantly higher than in other groups. Enzyme activity determination under different feeding inductions showed slightly higher enzyme activity in the basic diet group and crustacean group. The results of in situ hybridization showed that the mRNA of both OpPGA1 and OpPGA2 genes was both expressed in gastric gland cells. These information can contribute to the development of practical feeding methods in terms of digestive physiology for the development of larvae.

Analysis of gastrin-17 and its related influencing factors in physical examination results

BACKGROUND

To analyze the difference of serum gastrin-17 (G17) level in healthy people with different sex, age, and body mass index (BMI), to explore the correlation between G17 and pepsinogen, and to study the influences of Helicobacter pylori (H. pylori) infection and various inflammatory factors on G17 secretion level.

METHODS

A total of 531 subjects who received physical examination in our center from April 2019 to December 2019 were enrolled in the study. All subjects were tested for G17, pepsinogen I (PGI), pepsinogen II (PGII), PGI/PGII ratio (PGR), H. pylori, serum amyloid A (SAA), C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). The difference of G17 secretion in different subjects and its correlation with PG were analyzed to investigate H. pylori infection and expound the effects of inflammatory indicators on G17.

RESULTS

There was no significant difference in G17 secretion level in people with different sex, age and BMI (p > .05). G17 positively correlated with PGI and PGII, but negatively correlated with PGR. The G17 level of H. pylori-positive subjects was 10.16 ± 12.84, and prominently higher than that of H. pylori-negative subjects (3.27 ± 6.65). SAA and H. pylori infection were the greater risk factors for G17 abnormality among various indicators. CRP and ESR had no effect on G17 abnormality.

CONCLUSIONS

G17 secretion is closely related to PG and H. pylori. Combined screening contributes to early screening of gastrointestinal diseases in normal people or groups at high risk for gastric cancer, but the influence of inflammatory indicators on G17 should be excluded to improve the reliability of the results.

The Controversy of Pepsinogen A/Pepsin A in Detecting Extra-Gastroesophageal Reflux

BACKGROUND

Pepsinogen A (PGA)/pepsin A is often used as a diagnostic marker of extra-gastroesophageal reflux. We aimed to explore whether its positivity in upper aerodigestive tract (UADT) was specific enough to diagnose reflux.

METHODS

PGA/pepsin A protein levels were examined in 10 types of tissues and 10 types of body fluid by immunological staining, western blot or Elisa, using three different commercially available brands simultaneously. Liquid chromatography-tandem mass spectrometry parallel reaction monitoring (LC-MS/MS PRM) served as a gold reference for the detection of PGA/pepsin A proteins. PGA gene expression was analyzed by reverse transcriptase sequencing methods for tissue samples. Specifically, 24 hour pH monitoring technique was conducted for patients who donated saliva samples.

RESULTS

Eight out of ten types of human tissue samples (stomach, esophagus, lung, kidney, colon, parotid gland, nasal turbinate and nasal polyps) were confirmed positive for PGA/pepsin A gene and protein by genetic and PRM technique, respectively. Two out of ten types of body fluid samples (gastric fluid, urine) were confirmed positive for PGA/pepsin A protein by PRM technique. The consistence rates of PGA/pepsin A positivity among three commercial antibody brands and Elisa kit were poor, and Elisa results of salivary did not match with 24-hour pH monitoring.

CONCLUSIONS

Multiple tissues and body fluid could be detected baseline expression levels of PGA/pepsin A gene and protein. However, those commercially available PGA/pepsin A antibodies achieved poor sensitivity and specificity, therefore, relying on the detection of PGA/pepsin A in UADT by single antibodies to diagnose extra-gastroesophageal reflux without a specific positive cut-off value is unreliable.

Pepsinogen I- and H+/K+-ATPase-immunohistochemical Positivity in Endoscopically Resected Early Gastric Neoplasia

Gastric adenocarcinoma of the fundic gland type (GAFG) has been recently classified by the World Health Organization (WHO), however, clinicopathologic features of pepsinogen I- or H+/K+-ATPase-positive gastric tumors remain unclear. Therefore, this study evaluates the frequency and clinicopathologic features of those tumors, using a tissue microarray block to identify pepsinogen I- or H+/K+-ATPase-positive tumors from 810 endoscopically resected, early gastric epithelial tumors. The frequency of pepsinogen I-positive lesions was 2.1%, and that of H+/K+-ATPase-positive lesions was 2.0%. Pepsinogen I- or H+/K+-ATPase positivity was not observed in undifferentiated-type tumors, while gastric tumors with morphologic similarity to fundic glands were positive for pepsinogen I- or H+/K+-ATPase. We divided pepsinogen I- or H+/K+-ATPase-positive gastric tumors into group A, with fundic gland-like structure, or group B, without fundic gland-like structure. The frequency of group A was 1.6%: 46.2% were positive only for pepsinogen I and 53.8% for H+/K+-ATPase and pepsinogen I. The frequency of group B was 1.5%: 25% were positive only for pepsinogen I, 8.3% for H+/K+-ATPase and pepsinogen I, and 66.7% only for H+/K+-ATPase. The 2 tumor groups differed in location and endoscopic features. Hematoxylin and eosin staining showed that group B had more exposed tumors to the surface, larger nuclei, and more background atrophy than group A. Immunostaining showed significantly higher positivity rates for MUC5AC, CD10, CDX2, and p53 expression, and a higher Ki-67 labeling score. Our results provide novel insights into the pathology of early gastric tumors with histologic or immunohistochemical evidence of fundic gland differentiation.

Activation of dopamine D2 receptor promotes pepsinogen secretion by suppressing somatostatin release from the mouse gastric mucosa

In vivo administration of dopamine (DA) receptor (DR)-related drugs modulate gastric pepsinogen secretion. However, DRs on gastric pepsinogen-secreting chief cells and DA D2 receptor (D2R) on somatostatin-secreting D cells were subsequently acquired. In this study, we aimed to further investigate the local effect of DA on gastric pepsinogen secretion through DRs expressed on chief cells or potential D2Rs expressed on D cells. To elucidate the modulation of DRs in gastric pepsinogen secretion, immunofluorescence staining, ex vivo incubation of gastric mucosa isolated from normal and D2R-/- mice were conducted, accompanied by measurements of pepsinogen or somatostatin levels using biochemical assays or enzyme-linked immunosorbent assays. D1R, D2R, and D5R-immunoreactivity (IR) were observed on chief cells in mouse gastric mucosa. D2R-IR was widely distributed on D cells from the corpus to the antrum. Ex vivo incubation results showed that DA and the D1-like receptor agonist SKF38393 increased pepsinogen secretion, which was blocked by the D1-like receptor antagonist SCH23390. However, D2-like receptor agonist quinpirole also significantly increased pepsinogen secretion, and D2-like receptor antagonist sulpiride blocked the promotion of DA. Besides, D2-like receptors exerted an inhibitory effect on somatostatin secretion, in contrast to their effect on pepsinogen secretion. Furthermore, D2R-/- mice showed much lower basal pepsinogen secretion but significantly increased somatostatin release and an increased number of D cells in gastric mucosa. Only SKF38393, not quinpirole, increased pepsinogen secretion in D2R-/- mice. DA promotes gastric pepsinogen secretion directly through D1-like receptors on chief cells and indirectly through D2R-mediated suppression of somatostatin release.

A retrospective study assessing the acceleration effect of type I Helicobacter pylori infection on the progress of atrophic gastritis

Based on the antibody typing classification, Helicobacter pylori infection can be divided into type I H. pylori infection and type II H. pylori infection. To observe the effects of different H. pylori infection types on the distribution of histopathological characteristics and the levels of three items of serum gastric function (PG I, PG II, G-17). 1175 cases from October 2018 to February 2020 were collected with ratio 1:2. All patients were performed with ¹⁴C-Urea breath test (¹⁴C-UBT), H. pylori antibody typing classification, three items of serum gastric function detection, painless gastroscopy, pathological examination, etc. According to H. pylori antibody typing classification, patients were divided into three groups: type I H. pylori infection group, type II H. pylori infection group and control group. Significant difference existed among type I H. pylori infection group, type II H. pylori infection group and control group in inflammation and activity (χ² = 165.43, 354.88, P all < 0.01). The proportion of three groups in OLGA staging had statistic difference (χ² = 67.99, P all < 0.01); Compared with type II H. pylori infection group and control group, the level of pepsinogen I, pepsinogen II, gastrin17 in type I H. pylori infection group increased, and PG I/PG II ratio (PG I/PG II ratio, PGR) decreased, which was statistically significant (χ² = 35.08, 166.24, 134.21, 141.19; P all < 0.01). Type I H. pylori infection worsened the severity of gastric mucosal inflammation and activity. H. pylori infection was prone to induce atrophy of gastric mucosa, while type I H. pylori infection played a key role in promoting the progress of atrophic gastritis and affected the level of serum gastric function. The study indicated that the eradication of H. pylori should be treated individually.

Human gastric cancer risk screening: From rat pepsinogen studies to the ABC method

We examined the development of gastric cancer risk screening, from rat pepsinogen studies in an experimental rat gastric carcinogenesis model induced with N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) and human pepsinogen studies in the 1970s and 1980s to the recent "ABC method" for human gastric cancer risk screening. First, decreased expression or absence of a major pepsinogen isozyme, PG1, was observed in the rat gastric mucosa from the early stages of gastric carcinogenesis to adenocarcinomas following treatment with MNNG. In the 1980s, decreases in PGI in the human gastric mucosa and serum were identified as markers of atrophic gastritis. In the 1990s, other researchers revealed that chronic infection with Helicobacter pylori (Hp) causes atrophic gastritis and later gastric cancer. In the 2000s, a gastric cancer risk screening method combining assays to detect serum anti-Hp IgG antibody and serum PGI and PGII levels, the "ABC method", was established. Eradication of Hp and endoscopic follow-up examination after the ABC method are recommended to prevent gastric cancer.

A comparative study on changes in intestinal flora, pepsinogen and gastrin in patients with gastric cancer and atrophic gastritis

1Department of General Surgery, The No.1 Hospital of Shijiazhuang, Shijiazhuang, China.

Helicobacter pylori antibody and pepsinogen testing for predicting gastric microbiome abundance

Background

Although the high-throughput sequencing technique is useful for evaluating gastric microbiome, it is difficult to use clinically. We aimed to develop a predictive model for gastric microbiome based on serologic testing.

Methods

This study was designed to analyze sequencing data obtained from the Hanyang University Gastric Microbiome Cohort, which was established initially to investigate gastric microbial composition according to the intragastric environment. We evaluated the relationship between the relative abundance of potential gastric cancer-associated bacteria (nitrosating/nitrate-reducing bacteria or type IV secretion system [T4SS] protein gene-contributing bacteria) and serologic markers (IgG anti-Helicobacter pylori [HP] antibody or pepsinogen [PG] levels).

Results

We included 57 and 26 participants without and with HP infection, respectively. The relative abundance of nitrosating/nitrate-reducing bacteria was 4.9% and 3.6% in the HP-negative and HP-positive groups, respectively, while that of T4SS protein gene-contributing bacteria was 20.5% and 6.5% in the HP-negative and HP-positive groups, respectively. The relative abundance of both nitrosating/nitrate-reducing bacteria and T4SS protein gene-contributing bacteria increased exponentially as PG levels decreased. Advanced age (only for nitrosating/nitrate-reducing bacteria), a negative result of IgG anti-HP antibody, low PG levels, and high Charlson comorbidity index were associated with a high relative abundance of nitrosating/nitrate-reducing bacteria and T4SS protein gene-contributing bacteria. The adjusted coefficient of determination (R²) was 53.7% and 70.0% in the model for nitrosating/nitrate-reducing bacteria and T4SS protein gene-contributing bacteria, respectively.

Conclusion

Not only the negative results of IgG anti-HP antibody but also low PG levels were associated with a high abundance of nitrosating/nitrate-reducing bacteria and T4SS protein gene-contributing bacteria.

Effect of different salinities on gene expression and activity of digestive enzymes in the thick-lipped grey mullet (Chelon labrosus)

The effects of different environmental salinities (0, 12, 40, and 55 ppt) on pepsinogen 2 (pga2), trypsinogen 2 (try2), chymotrypsinogen (ctr), and pancreatic alpha-amylase (amy2a) gene expression, and on the total activities of their corresponding enzymes, were assessed in Chelon labrosus juveniles, after their corresponding full-complementary DNA sequences were cloned. Furthermore, the quantitative effect of different salinities on the hydrolysis of feed protein by fish digestive enzymes was evaluated using an in vitro system. Relative pga2 expression levels were significantly higher in animals maintained at 12 ppt, while a significantly higher gene expression level for ctr and try2 was observed at 40 ppt. amy2a gene expression showed its maximum level at 40 ppt and the lowest at 55 ppt. A significant reduction in the activity of amylase with the increase in salinity was observed, whereas the maximum activity for alkaline proteases was observed in individuals maintained at 40 ppt. A negative effect of high salinity on the action of proteases was confirmed by the in vitro assay, indicating a decreased efficiency in the digestive function in C. labrosus when maintained at high environmental salinities. Nevertheless, individuals can live under different environmental salinities, even though gene expression is different and the enzymatic activities are not maintained at the highest studied salinity. Therefore, compensatory mechanisms should be in place. Results are discussed on the light of the importance as a new species for aquaculture.

Clinicopathological characteristics of duodenal epithelial neoplasms: Focus on tumors with a gastric mucin phenotype (pyloric gland-type tumors)

Objective

Epithelial tumors less commonly occur in the duodenum than in the stomach or large intestine. The clinicopathological characteristics of duodenal epithelial tumors remain a matter of debate. We therefore studied resected specimens to investigate the clinicopathological characteristics of duodenal epithelial tumors.

Materials and methods

Among duodenal epithelial tumors resected endoscopically or surgically in our hospital, we studied the clinicopathological characteristics of 110 adenomas or intramucosal carcinomas. The grade of atypia of all tumors was classified into 3 groups according to the World Health Organization (WHO) 2010 classification. The tumors were immunohistochemically evaluated to determine the frequency of differentiation toward fundic glands.

Results

As for patient characteristics, there were 76 men (75.2%) and 25 women (24.8%), with a median age of 65 years (range, 34 to 84). The tumors most commonly arose in the first to second part of the duodenum. Many lesions were flat, and the median tumor diameter was 8.0 mm. The lesions were classified into 2 types according to mucin phenotype: intestinal-type tumors (98 lesions, 89.1%) and gastric-type tumors (12 lesions, 10.9%). Intestinal-type tumors were subdivided into 2 groups: tubular-type tumors (91 lesions, 82.7%) and tubulovillous-type tumors (7 lesions, 6.4%). Gastric-type tumors were classified into 2 types: foveolar type (3 lesions, 2.7%) and pyloric gland-type (PG) tumors (9 lesions, 8.2%). The grade of atypia was significantly higher in gastric-type tumors (p<0.01). PG tumors were gastric-type tumors characterized by pyloric glands and findings suggesting differentiation toward fundic glands.

Conclusions

About 10% of the duodenal tumors had a gastric-type mucin phenotype. Gastric-type tumors showed high-grade atypia. In particular, PG tumors showed similarities to PG tumors of the stomach, such as differentiation toward fundic glands.

Endoscopic gastritis, serum pepsinogen assay, and Helicobacter pylori infection

Endoscopic findings of the background gastric mucosa are important in the Helicobacter pylori-seroprevalent population. It is strongly correlated not only with the risk of gastric cancer, but also with the excretion ability of gastric mucosa cells. In noninfected subjects, common endoscopic findings are regular arrangement of collecting venules, chronic superficial gastritis, and erosive gastritis. In cases of active H. pylori infection, nodularity on the antrum, hemorrhagic spots on the fundus, and thickened gastric folds are common endoscopic findings. The secreting ability of the gastric mucosa cells is usually intact in both noninfected and actively infected stomachs, and the intragastric condition becomes hyperacidic upon inflammation. Increased serum pepsinogen II concentration correlates well with active H. pylori infection, and also indicates an increased risk of diffuse-type gastric cancer. In chronic inactive H. pylori infection, metaplastic gastritis and atrophic gastritis extending from the antrum (closed-type chronic atrophic gastritis) toward the corpus (open-type chronic atrophic gastritis) are common endoscopic findings. The intragastric environment is hypoacidic and the risk of intestinal-type gastric cancer is increased in such conditions. Furthermore, there is a decrease in serum pepsinogen I concentration when the secreting ability of the gastric mucosa cells is damaged. Serologic and endoscopic changes that occur upon H. pylori infection are important findings for estimating the secreting ability of the gastric mucosa cells, and could be applied for the secondary prevention of gastric cancer.

Helicobacter Pylori and Laryngopharyngeal Reflux in Chronic Rhinosinusitis

OBJECTIVES: Investigation of the potential role of several laryngopharyngeal reflux contents in sinus disease.

STUDY DESIGN AND SETTING: A controlled cohort analysis of Helicobacter pylori, pepsin and pepsinogen I in inflamed and non-inflamed sinonasal tissue. Fifteen patients, selected for surgery due to chronic medically refractory rhinosinusitis, had their pathologic sinus tissue analyzed for polymerase chain reaction detection of H. pylori DNA and assayed for pepsin and pepsinogen I tissue concentration levels. A control group of 5 patients undergoing surgery for anatomic sinonasal abnormalities provided non-inflammatory mucosa specimens for comparison.

RESULTS: H. pylori was found scattered in inflamed and non-inflamed mucosa, whereas sinonasal tissue pepsin/pepsinogen never rose above blood levels in both groups.

CONCLUSIONS: Evidence of intra-operative peptic reflux into the sinuses was not found. As H. pylori was similarly encountered in healthy and diseased sinus mucosa, it seemingly fails to support a pathogenic role for this organism in the sinuses.

EBM rating: B-2b

Genetic Ablation of the ClC-2 Cl- Channel Disrupts Mouse Gastric Parietal Cell Acid Secretion

The present studies were designed to examine the effects of ClC-2 ablation on cellular morphology, parietal cell abundance, H/K ATPase expression, parietal cell ultrastructure and acid secretion using WT and ClC-2^-/- mouse stomachs. Cellular histology, morphology and proteins were examined using imaging techniques, electron microscopy and western blot. The effect of histamine on the pH of gastric contents was measured. Acid secretion was also measured using methods and secretagogues previously established to give maximal acid secretion and morphological change. Compared to WT, ClC-2^-/- gastric mucosal histological organization appeared disrupted, including dilation of gastric glands, shortening of the gastric gland region and disorganization of all cell layers. Parietal cell numbers and H/K ATPase expression were significantly reduced by 34% (P<0.05) and 53% (P<0.001) respectively and cytoplasmic tubulovesicles appeared markedly reduced on electron microscopic evaluation without evidence of canalicular expansion. In WT parietal cells, ClC-2 was apparent in a similar cellular location as the H/K ATPase by immunofluorescence and appeared associated with tubulovesicles by immunogold electron microscopy. Histamine-stimulated [H⁺] of the gastric contents was significantly (P<0.025) lower by 9.4 fold (89%) in the ClC-2^-/- mouse compared to WT. Histamine/carbachol stimulated gastric acid secretion was significantly reduced (range 84–95%, P<0.005) in ClC-2^-/- compared to WT, while pepsinogen secretion was unaffected. Genetic ablation of ClC-2 resulted in reduced gastric gland region, reduced parietal cell number, reduced H/K ATPase, reduced tubulovesicles and reduced stimulated acid secretion.

[The expression and clinical significance of pepsin and pepsinogen in patients with otitis media with effusion]

OBJECTIVE

To analyze the role and significance of pepsin and pepsinogen in the pathogenesis of OME in children.

METHOD

Pediatric patients with otitis media aged 2-8 years who enrolled in our department of the hospital from May of 2012 to December of 2012 were set as experimental group (38 cases, 48 ears) which should be underwent tympanic membrane puncture/tube insertion. Meanwhile, pediatric patients waiting for cochlear implant without otitis media (10 ears), were set as control group. Middle ear lavage fluid and plasma samples from the two groups were collected and detected using enzyme-linked immune method for pepsin and pepsinogen.

RESULT

The concentrations of pepsin and pepsinogen in the middle ear lavage fluid of OME group [(48.8 ± 415.99) ng/ml and 676.32 ± 336.71)ng/ml] were significantly higher than those in the control group [(8.20 ± 4.59)ng/ml and (77.27 ± 50.33) ng/ml] (P < 0.01). Meanwhile, the concentration of pepsinogen in the middle ear lavage of OME patients was significantly higher than that of plasma (P < 0.01). The concentration of pepsin in the middle ear lavage fluid from the dry ear subgroup was lower than those in the serum ear and mucous ear subgroups (P < 0.01), but there was no significant difference about concentrations of pepsinogen among the dry ear, serum ear and mucous ear subgroups (P > 0.05).

CONCLUSION

Pepsin and pepsinogen in the middle ear cavity of OME patients maybe originated from laryngopharyngeal reflux (LPR), indicating that LPR is associated with the pathogenesis of OME in children.

Effects of polymorphisms in pepsinogen (PEP), amylase (AMY) and trypsin (TRY) genes on food habit domestication traits in mandarin fish

Mandarin fish (Siniperca chuatsi) have a peculiar feeding habit of only accepting live fish prey and refusing dead prey and artificial diets. However, previous research has shown that some individuals accept dead prey after gradual domestication. Digestive enzymes are correlated with feeding habits in fish. In the current study, SNPs in the mandarin fish genes for pepsinogen (PEP), amylase (AMY), and trypsin (TRY) were evaluated for associations with feeding habits in domesticated mandarin fish by scanning their complete genomic sequence. In total, two SNPs were found in PEP, one was found in TRY, and none were found in AMY. The D1(CTCC) and D5(TTTT) diplotypes in the PEP gene tended to show strong effects on the feeding habits of domesticated fish (p < 0.01). The results indicate that PEP may be associated with the genetic mechanism for feeding habits in mandarin fish, and the D1(CTCC) and D5(TTTT) diplotypes in the PEP gene may be useful markers for selecting mandarin fish with appropriate feeding habits for domestication.

[The clinical significance of GastroPanel in diagnostics of Helicobacter pylori eradication efficiency in patients with dyspepsia with correlation of family history of gastric cancer]

Gastric cancer remains a significant medical and social problem. Familial, hereditary, social, and demographic factors increase the susceptibility of subjects to cancer development, especially those infected with Helicobacter pylori (H. pylori). Apart from genetic studies, there are ongoing biochemical studies of possible practical value in assessment of the risk of gastric cancer development. The GastroPanelBiohit test, that include determination of the levels of gastrin (G-17), pepsinogen I (PGI), pepsinogen II (PGII) and antibodies IgG/IgA against H. pylori in serum, allowed us to determine whether there are any abnormal changes in the gastric mucosa. The aim of the study was to determine whether GastroPanel parameters, identified in patients with dyspeptic symptoms (with or without history of gastric cancer in first degree relatives) before and after successful eradication of H. pylori, have any clinical value, especially in gastric cancer development.

MATERIAL AND METHODS

The study comprised 61 patients aged 18-56 years with symptoms of dyspepsia. In all patients, the preliminary urea breath test (UBT) for the presence of H. pylori was performed and the positive result qualified for further study. For final analysis, 42 patients were approved, who were divided into two groups: group I (a control group) - 22 patients with negative family history of gastric cancer among the relatives of first degree, group II - 20 patients with positive history of gastric cancer among the relatives of first degree. All the patients had the gastroscopy with the biopsy of gastric mucosa for the histopathological evaluation. Additionally, the GastroPanel test was performed.

RESULTS

In the blood serum of the patients with H. pylori infection, the concentrations of gastrin (G-17), pepsinogen I (PGI) and pepsinogen II (PGII) did not depend on family history of gastric cancer (p > 0.05). Successful eradication of H. pylori decreases the levels of G-17, PGI and PGII (statistical significance p < 0.05), and this correlates with the histopathological changes of gastric mucosa. The patients with positive family history of gastric cancer had more intense H. pylori colonization of gastric mucosa (IV degree of insensitivity of infection in UBT; group I - 22% vs group II - 69%) as compared to the control group. After effective eradication of H. pylori, statistically significant decreases of IgG H. pylori antibodies and of the level of gastrin (p < 0.05) in blood serum were seen (in a 3 months follow up) only in the control group.

CONCLUSIONS

Independently of the history of familial gastric cancer, the GastroPanelBiohit test provides important clinical data useful for diagnosis, for assessment of effectiveness of H. pylori eradication therapy and in evaluation of the degree of the inflammatory changes in gastric mucosa.

H. pylori CagL-Y58/E59 prime higher integrin α5β1 in adverse pH condition to enhance hypochlorhydria vicious cycle for gastric carcinogenesis

Background/Aims

H. pylori CagL amino acid polymorphisms such as Y58/E59 can increase integrin α5β1 expression and gastric cancer risk. Hypochlorhydria during chronic H. pylori infection promotes gastric carcinogenesis. The study test whether CagL-Y58/E59 isolates may regulate integrin α5β1 to translocate CagA via the type IV secretory system even under adverse pH conditions, and whether the integrin α5β1 expression primed by H. pylori is a pH-dependent process involving hypochlorhydria in a vicious cycle to promote gastric carcinogenesis.

Methods

The expressions of integrin α5 and β1, CagA phosphorylation, IL-8, FAK, EGFR, and AKT activation of AGS cells exposed to CagL-Y58/E59 H. pylori, isogenic mutants, and different H. pylori CagL amino acid replacement mutants under different pH values were determined. Differences in the pepsinogen I/II ratio (indirectly indicating gastric acidity) and gastric integrin α5β1 expression were compared among the 172 H. pylori-infected patients with different cancer risks.

Results

Even under adversely low pH condition, H. pylori CagL-Y58/E59 still keep active integrin β1 with stronger binding affinity, CagA translocation, IL-8, FAK, EGFR, and AKT activation than the other mutants (p<0.05). The in vitro assay revealed higher priming of integrin α5β1 by H. pylori under elevated pH as hypochlorhydria (p<0.05). In the H. pylori-infected patients, the gastric integrin α5β1 expressions were higher in those with pepsinogen I/II ratio <6 than in those without (p<0.05).

Conclusions

H. pylori CagL-Y58/E59 prime higher integrin under adverse pH and may involve to enhance hypochlorhydria vicious cycle for gastric carcinogenesis, and thus require an early eradication.

Exploratory findings of audiometry in adult patients with otitis media with high pepsinogen concentrations: a preliminary study

CONCLUSIONS

The present study showed that elevation of bone-conduction (BC) thresholds at low frequencies might be a characteristic audiometric finding in cases with otitis media with effusion (OME) with high pepsinogen (PG) concentrations.

OBJECTIVE

The objective of this study was to investigate whether there is any characteristic audiometric finding in adult cases with otitis media with high PG compared to those with low PG.

METHODS

Twenty-four adult patients with unilateral OME of undetermined etiology and high PG concentrations (> 500 ng/ml) in their middle ear effusions (high PG group) were selected. The air-conduction and BC thresholds of pure tone audiometry were compared between the affected and healthy ears. Results were compared to those in 23 patients with low PG concentrations (< 50 ng/ml; low PG group).

RESULTS

The average BC difference in the threshold at 0.25 kHz between the affected ear and the healthy ear was significantly higher in the high PG group than in the low PG group, with a significantly higher proportion of patients in the high PG group having BC thresholds at 0.25 kHz in the affected ear that were ≥ 15 dB higher than in the healthy ear.

[Restoration of secretory activity of digestive glands in conditions of acute hyperkinesis at persons with different levels of motor activity]

The dynamics' features of restoration reactions of the secretory function of gastric glands have been studied at patients with differences in the level and specificity of daily physical activity. The dependence between the level and characteristics of daily physical activity and reactivity of the secretory apparatus of the gastric glands in the recovery period after the muscle load has been established. The high reactivity of the secretory activity of digestive glands is typical for individuals with high level of daily physical activity. The differences of the functional stability of the secretion's mechanisms of various components of gastric juice under the influence of physical exercise and in recovery have been revealed. The greatest stability of the secretory mechanisms of digestive glands has been discovered at athletes practicing with the development of endurance--at skiers. Heterochronous reducing reactions of gastric and pancreatic secretion after physical stress have been defined. The reduction of secretion's mechanisms of gastric juice ingredients and the electrolyte and acid composition of digestive juices isn't simultaneous: the first order is for ferment's secretion. The inverse relationship between the content of digestive enzymes pepsinogen-1 and -2 in blood's serum and the concentration of proteolytic enzymes in the gastric content has been found at persons with various degrees of adaptation to the muscular tension.

Distribution of pepsinogen- and ghrelin-producing cells in the digestive tract of Japanese eel (Anguilla japonica) during metamorphosis and the adult stage

Pepsinogen is the precursor form of the gastric-specific digestive enzyme, pepsin. Ghrelin is a representative gastric hormone with multiple functions in vertebrates, including the regulation of growth hormone release, stimulation of food intake and gastrointestinal motility function. We investigated chronological changes in the distribution of pepsinogen-expressing cells by in situ hybridization and ghrelin-immunoreactive cells by immunohistochemistry in the Japanese eel (Anguilla japonica) during metamorphosis from the leptocephalus sage to the elver stage. The ghrelin-producing cells first appeared in the gastric cecum and pyloric portion of the stomach in the late phase of metamorphosing leptocephali, whereas the pepsinogen-producing cells were first detected in the early phase of the glass-eel stage. These suggest that endocrine cells differentiated earlier than exocrine cells in the eel stomach. Accompanying eel development, the distribution of ghrelin-producing cells spread to the esophagus and other regions of the stomach, but not to the intestine. These results may be related to the changes in dietary habits during metamorphosis in the Japanese eel.

[Clinical and laboratory evaluation of efficiency of Helicobacter pylori eradication]

AIM

To assess the efficiency of eradication therapy in long-term period using the main signs of functional activity of gastric mucosa (gastrin-17, pepsinogen I, pepsinogen II) and serum antibodies to H. pylori.

MATERIALS AND METHODS

113 patients with chronic gastritis were examihed using clinical, endoscopic and laboratory-based methods of investigation, including GastroPanel Biohit, Finland.

RESULTS

It was observed that after 12 month of successful eradication therapy the titer of IgG to H. pylori did not exceed 60 IU/l, with pepsinogen I and pepsinogen II cut-off values set under 150 microg/l and 15 microg/l respectively.

CONCLUSION

The decrease of the titer of IgG to H. pylori and concentrations of pepsinogen I and II can be used as criteria of successful eradication therapy in long-term period.

Influence of ghrelin on gastric and duodenal growth and expression of digestive enzymes in young mature rats

Ghrelin, a nature ligand for the growth hormone secretagogue receptor (GHS-R), stimulates a release of growth hormone, prolactin and adrenocorticotropic hormone. Also, ghrelin increases food intake in adult rats and humans and exhibits gastroprotective effect against experimental ulcers induced by ethanol or stress. The aim of present study was to examine the influence of ghrelin administration on gastric and duodenal growth and expression of pepsin and enterokinase in young mature rats with intact or removed pituitary.

METHODS

Two week after sham operation or hypophysectomy, eight week old Wistar male rats were treated with saline (control) or ghrelin (4, 8 or 16 nmol/kg/dose) i.p. twice a day for 4 days. Expression of pepsin in the stomach and enterokinase in the duodenum was evaluated by real-time PCR.

RESULTS

In animals with intact pituitary, treatment with ghrelin increased food intake, body weight gain and serum level of growth hormone and insulin-like growth factor-1 (IGF-1). These effects were accompanied with stimulation of gastric and duodenal growth. It was recognized as the significant increase in gastric and duodenal weight and mucosal DNA synthesis. In both organs, ghrelin administered at the dose of 8 nmol/kg caused maximal growth-promoting effect. In contrast to these growth-promoting effects, administration of ghrelin reduced expression of mRNA for pepsin in the stomach and was without effect on expression of mRNA for enterokinase in the duodenum. Hypophysectomy alone lowered serum concentration of growth hormone under the detection limit and reduced serum level of IGF-1 by 90%. These effects were associated with reduction in daily food intake, body weight gain and gastroduodenal growth. In hypophysectomized rats, administration of ghrelin was without significant effect on food intake, body weight gain or growth of gastroduodenal mucosa. Also, serum concentration of growth hormone or IGF-1 was not affected by ghrelin administration in rats with removed pituitary.

CONCLUSION

Administration of ghrelin stimulates gastric and duodenal growth in young mature rats with intact pituitary, but inhibits expression of mRNA for pepsin in the stomach. Growth hormone and insulin-like growth factor-1 play an essential role in growth-promoting effects of ghrelin in the stomach and duodenum.

Influence of aging, gastric mucosal atrophy and dietary habits on gastric secretion

BACKGROUND/AIMS

Studies in Japan have reported on the association between gastric secretion and age with consideration given to gastric mucosal atrophy but not pepsin secretion. Though recent reports have shown enhanced gastric secretion in the Japanese, attributed to dietary westernization, the association between diet and gastric secretion is not clear. In this study, the association between gastric secretion and mucosal atrophy, age, and dietary habits was evaluated.

METHODOLOGY

The subjects were 47 preoperative patients without upper gastrointestinal disorders. Acid secretion, pepsin secretion, serum pepsinogen level, and serum Helicobacter pylori antibody titer were measured. Dietary habits were investigated by questionnaire.

RESULTS

Gastric secretion did not differ among the young, middle, and elderly age groups. Compared with the group without atrophy (pepsinogen I/II > 3.0, 32 subjects), the group with atrophy (I/II < or = 2.5, 11 subjects) showed significantly decreased gastric secretion and a significantly high Helicobacter pyloriseropositive rate. In the group without atrophy, acid and pepsin secretion was significantly correlated with energy intake, pepsin secretion was significantly correlated with glucose intake, and gastric secretion tended to increase with age.

CONCLUSIONS

In the absence of gastric mucosal atrophy, gastric secretion does not decrease with age, and is related to dietary habits.

Pepsinogen and H,K-ATPase mediate acid secretion in gastric glands of Triturus carnifex (Amphibia, Caudata)

The gastric glands of Triturus carnifex (Amphibia, Caudata) have been examined by histochemical and immunohistochemical methods with particular regard to hydrochloric acid and pepsinogen secretion. Fundic glands consist of mucous neck cells, endocrine cells and oxynticopeptic cells producing both pepsinogen and hydrochloric acid. The neck cells showed an unexpected distribution pattern which was only observed in the oral fundus, and produced neutral mucins with glycosidic residues of GalNAc and Gal beta1,3GalNAc, and in this respect they differ from the neck cells of anuran amphibians. The secretion of pepsinogen and hydrochloric acid as demonstrated by immunolabelling with anti-H,K-ATPase and with anti-pepsinogen, respectively, seems not to vary significantly along the longitudinal axis of the stomach. The mechanism of gastric acid secretion seems to be mediated by an ATPase, having similar features to the mammalian gastric H,K-ATPase, and is localised in the luminal membrane and in the subapical cytoplasm of the oxynticopeptic cells. Unusually, the same cytoplasmic areas revealed binding specificity for the winged pea lectin (WPA) from Lotus tetragonolobus, even after beta elimination, indicating the presence of fucosyl residues in N-linked oligosaccharidic chains in glycoproteins of beta-H,K-ATPase subunits.

Contribution of the intra- and intermolecular routes in autocatalytic zymogen activation: application to pepsinogen activation

Taking as the starting point a recently suggested reaction scheme for zymogen activation involving intra- and intermolecular routes and the enzyme-zymogen complex, we carry out a complete analysis of the relative contribution of both routes in the process. This analysis suggests the definition of new dimensionless parameters allowing the elaboration, from the values of the rate constants and initial conditions, of the time course of the contribution of the two routes. The procedure mentioned above related to a concrete reaction scheme is extrapolated to any other model of autocatalytic zymogen activation involving intra- and intermolecular routes. Finally, we discuss the contribution of both of the activating routes in pepsinogen activation into pepsin using the values of the kinetic parameters given in the literature.

Use of enhanced green fluorescent protein to determine pepsin at high sensitivity

A fluorometric assay for pepsin and pepsinogen was developed using enhanced green fluorescent protein (EGFP) as a substrate. Acid denaturation of EGFP resulted in a complete loss of fluorescence that was completely reversible on neutralization. In the proteolytic assay procedure, acid-denatured EGFP was digested by pepsin or activated pepsinogen. After neutralization, the remaining amount of undigested EGFP refolded and was determined by fluorescence. Under standard digestion conditions, 4.8-24.0 ng pepsin or pepsinogen was used. Using porcine pepsin as a standard, 38+/-6.7 ng EGFP was digested per min-1 ng pepsin-1. Activated porcine pepsinogen revealed a similar digestion rate (37.2+/-5.2 ng EGFP min-1 ng activated pepsinogen-1). The sensitivity of the proteolysis assay depended on the time of digestion and the temperature. Increasing temperature and incubation time allowed quantification of pepsin or pepsinogen in a sample even in the picogram range. The pepsin-catalyzed EGFP digestion showed typical Michaelis-Menten kinetics. Km and Vmax values were determined for the pepsin and activated pepsinogen. Digestion of EGFP by pepsin revealed distinct cleavage sites, as analyzed by SDS-PAGE.

Role of Na-K-2Cl cotransporter-1 in gastric secretion of nonacidic fluid and pepsinogen

Na-K-2Cl cotransporter-1 (NKCC) has been detected at exceptionally high levels in the gastric mucosa of several species, prompting speculation that it plays important roles in gastric secretion. To investigate this possibility, we 1) immunolocalized NKCC protein in the mouse gastric mucosa, 2) compared the volume and composition of gastric fluid from NKCC-deficient mice and their normal littermates, and 3) measured acid secretion and electrogenic ion transport by chambered mouse gastric mucosa. NKCC was localized to the basolateral margin of parietal cells, mucous neck cells, and antral base cells. In NKCC-deficient mice, gastric secretions of Na+, K+, Cl-, fluid, and pepsinogen were markedly impaired, whereas secretion of acid was normal. After stimulation with forskolin or 8-bromo-cAMP, chambered corpus mucosa vigorously secreted acid, and this was accompanied by an increase in transmucosal electrical current. Inhibition of NKCC with bumetanide reduced current to resting levels but had no effect on acid output. Although prominent pathways for basolateral Cl- uptake (NKCC) and apical Cl- exit [cystic fibrosis transmembrane conductance regulator (CFTR)] were found in antral base cells, no impairment in gastric secretion was detected in CFTR-deficient mice. Our results establish that NKCC contributes importantly to secretions of Na+, K+, Cl-, fluid, and pepsinogen by the gastric mucosa through a process that is electrogenic in character and independent of acid secretion. The probable source of the NKCC-dependent nonacidic electrogenic fluid secretion is the parietal cell. The observed dependence of pepsinogen secretion on NKCC supports the concept that a nonacidic secretory stream elaborated from parietal cells facilitates flushing of the proenzyme from the gastric gland lumen.

Cholinergic agonist-induced pepsinogen secretion from murine gastric chief cells is mediated by M1 and M3 muscarinic receptors

Muscarinic cholinergic mechanisms play a key role in stimulating gastric pepsinogen secretion. Studies using antagonists suggested that the M3 receptor subtype (M3R) plays a prominent role in mediating pepsinogen secretion, but in situ hybridization indicated expression of M1 receptor (M1R) in rat chief cells. We used mice that were deficient in either the M1 (M1R-/-) or M3 (M3R-/-) receptor or that lacked both receptors (M(1/3)R-/-) to determine the role of M1R and M3R in mediating cholinergic agonist-induced pepsinogen secretion. Pepsinogen secretion from murine gastric glands was determined by adapting methods used for rabbit and rat stomach. In wild-type (WT) mice, maximal concentrations of carbachol and CCK caused a 3.0- and 2.5-fold increase in pepsinogen secretion, respectively. Maximal carbachol-induced secretion from M1R-/- mouse gastric glands was decreased by 25%. In contrast, there was only a slight decrease in carbachol potency and no change in efficacy when comparing M3R-/- with WT glands. To explore the possibility that both M1R and M3R are involved in carbachol-mediated pepsinogen secretion, we examined secretion from glands prepared from M(1/3)R-/- double-knockout mice. Strikingly, carbachol-induced pepsinogen secretion was nearly abolished in glands from M(1/3)R-/- mice, whereas CCK-induced secretion was not altered. In situ hybridization for murine M1R and M3R mRNA in gastric mucosa from WT mice revealed abundant signals for both receptor subtypes in the cytoplasm of chief cells. These data clearly indicate that, in gastric chief cells, a mixture of M1 and M3 receptors mediates cholinergic stimulation of pepsinogen secretion and that no other muscarinic receptor subtypes are involved in this activity. The development of a murine secretory model facilitates use of transgenic mice to investigate the regulation of pepsinogen secretion.

Identification of pepsinogen gene in the genome of stomachless fish, Takifugu rubripes

Pepsinogen is a precursor of pepsin, a gastric specific protease belonging to the aspartic proteinase family. In teleosts, several species, such as zebrafish and puffer, have independently lost gastric glands. So whether puffer have pepsinogen gene or not is an interesting issue. A search of GSS database for pufferfish, Takifugu rubripes, revealed five different aspartic proteinase genes in its genome. One of them (pPep) has typical pepsinogen structure and belongs to the fish pepsinogen cluster by phylogenic analysis. The pPep antisense probe hybridized to the gastric glands of flounder stomach. Therefore, we concluded that pPep is a pufferfish pepsinogen. The pufferfish pepsinogen mRNA was not expressed in the digestive organs but specifically in the skin. We speculated that while Tetraodontiformes evolutionarily lost gastric glands, pufferfish pepsinogen acquired an alternative function to food digestion.

The effects of continuous ambulatory peritoneal dialysis and hemodialysis on serum pepsinogen concentrations in patients with chronic renal failure

Pepsinogen, the precursors of pepsin, is classified into two subtypes: pepsinogen I (PG I) and pepsinogen II (PG II). Patients with impaired renal function are associated with elevated concentrations of serum pepsinogen. Contradictory results have been reported about the effect of dialysis on the serum pepsinogen levels, as the previous studies were conducted only in a particular period of dialysis. We therefore investigated the effect of continuous ambulatory peritoneal dialysis (CAPD) or hemodialysis on serum pepsinogen levels in patients with chronic renal failure (CRF) before and after dialysis treatment. Thirty-four patients with CRF were enrolled in this study and were treated by CAPD (n=22) or hemodialysis (n=12). As a control group, subjects with normal renal function were included (n=20). Serum PG I and PG II levels were measured in control subjects and CRF patients before dialysis treatment and after three-month dialysis treatment. Before dialysis treatment, serum PG I levels were significantly higher in CRF patients than control subjects. In patients treated by CAPD, the serum PG I levels were significantly decreased but its levels were still higher than the values of the control subjects, whereas PG I levels remained unchanged in patients treated by hemodialysis. There were no differences in serum PG II levels between control subjects and CRF patients before or after dialysis treatment. Thus, CAPD is more effective than hemodialysis in the clearance of PG I.

Th response to Helicobacter pylori differs between patients with gastric ulcer and duodenal ulcer

OBJECTIVE

Helicobacter pylori (H. pylori) infection induces both gastric (GU) and duodenal ulcers (DU). We examined whether host immunological response to H. pylori determines different disease outcomes.

MATERIAL AND METHODS

Thirty-two GU and 28 DU patients infected with H. pylori, and 24 dyspeptic patients without infection were enrolled. The constituents of cellular infiltrates in biopsies from each patient were determined and lymphokines secreted by stimulated T cells were measured. Serum concentrations of IgG subclasses specific to H. pylori were measured.

RESULTS

Low pepsinogen I and high pepsinogen II levels were observed in GU patients, while a high pepsinogen I level was found in DU patients. T cells predominate over other cell types in both GU and DU patients. GU patients had a higher number of T cells (p < 0.01) and lower plasma cells (p < 0.05) than those in DU patients. T cells from GU patients produced greater amounts of IFN-gamma and less IL-4 than those in DU patients (p < 0.01). GU patients had a higher serum level of IgG2 specific to H. pylori than that in DU patients (p < 0.01).

CONCLUSIONS

Th response by gastric T cells in GU patient was more polarized to Th1 as compared with that in DU patients, suggesting that a distinct immune response to H. pylori induces different disease outcomes.

Establishment of human gastric epithelial (HGE) cell lines exhibiting barrier function, progenitor, and prezymogenic characteristics

The unavailability of human cell lines representative of the gastric glandular epithelium while able to form a functional barrier restricts the application of a cell culture approach to the field of gastric epithelial physiology. In the current study, we have characterized new non-transfected clones isolated from gastric carcinoma cell lines known to express functional markers of the human gastric mucosa (J Cell Biochem 2001;81:241). Twenty-one clones exhibiting epithelial-type junctions (renamed HGE cell lines) were isolated from NCI-N87 (ATCC CRL 5822), whereas only squamous cell lines could be generated from other native strains. Of these 21 clones, HGE-17 and HGE-20 formed dense coherent monolayers and displayed true epithelial phenotype. E-cadherin and ZO-1 proteins were consistently localized at the periphery of all cells which also generated transepithelial electrical resistance. Moreover, growth factors known to be trophic for the gastric mucosa were able to stimulate mitogenesis at subconfluence. HGE-17 exhibited a poorly differentiated precursor-like status and responded strongly to EGF/TGFalpha treatment in restitution assays. HGE-20 cells, on the other hand, exhibited a higher degree of differentiation at the ultrastructural level as well as higher gastric lipase and pepsinogen levels. These latter zymogens were compartmentalized into granules which also contained mucin-6 (MUC6, prezymogenic-like status). Exogenous hormones, i.e., 1 mug/ml hydrocortisone and 5 microM retinoic acid, significantly increased enzyme levels in HGE-20. In conclusion, HGE-17 and HGE-20 represent the first human gastric cell lines with true epithelial characteristics, opening a venue to important applications for the study of re-epithelization, permeability, and regulation of digestive functions in the context of gastric physiology and pathology.

Kinetics of autocatalytic zymogen activation measured by a coupled reaction: pepsinogen autoactivation

A kinetic study was performed of a model for an autocatalytic zymogen activation process involving both intra- and intermolecular routes, to which a chromogenic reaction in which the active enzyme acts upon one of its substrates was coupled to continuously monitor the reaction. Kinetic equations describing the evolution of species involved in the system with time were obtained. These equations are valid for any zymogen autocatalytic activation process under the same initial conditions. Experimental design and kinetic data analysis procedures to evaluate the kinetic parameters, based on the derived kinetic equations, are suggested. In addition, a dimensionless distribution coefficient was defined, which shows mathematically whether the intra- or the intermolecular route prevails once the kinetic parameters involved in the system are known. The validity of the results obtained was checked using simulated curves for the species involved. As an example of application of the method, the system is experimentally illustrated by the continuous monitoring of pepsinogen transformation to pepsin.

Kinetics of intra- and intermolecular zymogen activation with formation of an enzyme-zymogen complex

A mathematical description was made of an autocatalytic zymogen activation mechanism involving both intra- and intermolecular routes. The reversible formation of an active intermediary enzyme-zymogen complex was included in the intermolecular activation route, thus allowing a Michaelis-Menten constant to be defined for the activation of the zymogen towards the active enzyme. Time-concentration equations describing the evolution of the species involved in the system were obtained. In addition, we have derived the corresponding kinetic equations for particular cases of the general model studied. Experimental design and kinetic data analysis procedures to evaluate the kinetic parameters, based on the derived kinetic equations, are suggested. The validity of the results obtained were checked by using simulated progress curves of the species involved. The model is generally good enough to be applied to the experimental kinetic study of the activation of different zymogens of physiological interest. The system is illustrated by following the transformation kinetics of pepsinogen into pepsin.

Pepsinogen secretion in cholecystokinin-1 receptor-deficient rats

We examined the roles of cholecystokinin (CCK)-2 receptors in the regulation of pepsinogen secretion in the CCK-1 receptor deficient Otsuka Long-Evans Tokushima Fatty (OLETF) rats. Pepsinogen secretion was determined in fasted acute fistula OLETF and control Long-Evans Tokusima Otsuka (LETO) rats. Pepsinogen secretion in OLETF rats under basal conditions as well as in response to CCK-8 stimulation was significantly higher than that in LETO rats. CCK-1 receptor specific agonist ARL 15849 was unable to stimulate pepsinogen secretion in OLETF rats, whereas it elicited pepsinogen secretion in LETO rats to levels similar to those obtained with equimolar CCK-8 stimulation. CCK-2 receptor antagonist reduced basal pepsinogen secretion and completely abolished CCK-8-stimulated pepsinogen output in OLETF rats, whereas in LETO rats, it reduced basal pepsinogen secretion but augmented CCK-8-stimulated pepsinogen output. CCK-1 receptor antagonist loxiglumide also greatly decreased CCK-8-stimulated pepsinogen secretion in OLETF rat, which indicates that loxiglumide is not a specific CCK-1 receptor antagonist. Intravenous infusion of somatostatin antagonist significantly increased CCK-8-stimulated pepsinogen secretion in LETO rats, whereas it had no significant influence on CCK-8-stimulated pepsinogen secretion in OLETF rats. These results indicate that CCK-8 stimulates pepsinogen secretion via CCK-2 receptors in CCK-1 receptor deficient OLETF rats and that the higher CCK-8-stimulated as well as basal pepsinogen secretion in OLETF rats might result from an elimination of tonic inhibition by somatostatin that is released from D cells through mainly CCK-1 receptors.

Extracellular calcium acts as a "third messenger" to regulate enzyme and alkaline secretion

It is generally assumed that the functional consequences of stimulation with Ca²⁺-mobilizing agonists are derived exclusively from the second messenger action of intracellular Ca²⁺, acting on targets inside the cells. However, during Ca²⁺ signaling events, Ca²⁺ moves in and out of the cell, causing changes not only in intracellular Ca²⁺, but also in local extracellular Ca²⁺. The fact that numerous cell types possess an extracellular Ca²⁺ “sensor” raises the question of whether these dynamic changes in external [Ca²⁺] may serve some sort of messenger function. We found that in intact gastric mucosa, the changes in extracellular [Ca²⁺] secondary to carbachol-induced increases in intracellular [Ca²⁺] were sufficient and necessary to elicit alkaline secretion and pepsinogen secretion, independent of intracellular [Ca²⁺] changes. These findings suggest that extracellular Ca²⁺ can act as a “third messenger” via Ca²⁺ sensor(s) to regulate specific subsets of tissue function previously assumed to be under the direct control of intracellular Ca²⁺.

Cloning of the authentic bovine gene encoding pepsinogen a and its expression in microbial cells

Bovine pepsin is the second major proteolytic activity of rennet obtained from young calves and is the main protease when it is extracted from adult animals, and it is well recognized that the proteolytic specificity of this enzyme improves the sensory properties of cheese during maturation. Pepsin is synthesized as an inactive precursor, pepsinogen, which is autocatalytically activated at the pH of calf abomasum. A cDNA coding for bovine pepsin was assembled by fusing the cDNA fragments from two different bovine expressed sequence tag libraries to synthetic DNA sequences based on the previously described N-terminal sequence of pepsinogen. The sequence of this cDNA clearly differs from the previously described partial bovine pepsinogen sequences, which actually are rabbit pepsinogen sequences. By cloning this cDNA in different vectors we produced functional bovine pepsinogen in Escherichia coli and Saccharomyces cerevisiae. The recombinant pepsinogen is activated by low pH, and the resulting mature pepsin has milk-clotting activity. Moreover, the mature enzyme generates digestion profiles with alpha-, beta-, or kappa-casein indistinguishable from those obtained with a natural pepsin preparation. The potential applications of this recombinant enzyme include cheese making and bioactive peptide production. One remarkable advantage of the recombinant enzyme for food applications is that there is no risk of transmission of bovine spongiform encephalopathy.

Co-secretion of soluble caveolin-1 and pepsinogen in the oesophagus of the red-legged frog Rana aurora aurora

Caveolin-1, an integral membrane protein, is the principal component of caveolae, which are specialised vesicular microdomains of the plasma membrane. Caveolae are found in most cell types, but they are most abundant in adipocytes, endothelial cells, fibroblasts, and muscle cells. Functionally, they have been implicated in endothelial transcytosis, potocytosis, and signal transduction. Recently, caveolin-1 has been found unexpectedly in the cytoplasm, mitochondria and elements of the secretory pathways of exocrine secretory cells. We have co-localised caveolin-1 and pepsinogen immunohistochemically in serous cells of oesophageal glands of the red-legged frog, Rana aurora aurora. Thus, according to its intracellular localisation pattern, caveolin-1 may be either a soluble protein, located in secretory droplets, or a protein that is inserted in caveolar membranes. Soluble caveolin-1, which is probably embedded in a lipid particle surrounded by a phospholipid shell, may be involved in intracellular and extracellular lipid transport. In the gut, caveolin-1-rich lipid particles can act as donor particles to facilitate (protein-mediated) intestinal uptake of cholesterol and phospholipids. Our findings strengthen the hypothesis that caveolin-1 has a physiological autocrine/paracrine function and demonstrate that secretion of this protein also occurs in vertebrates other than mammals, such as amphibians, which may be a useful alternative animal model to study caveolin-1.

The PAR-1-activating peptide facilitates pepsinogen secretion in rats

Protease-activated receptor-2 (PAR-2) is abundantly expressed in gastric mucosal chief cells, facilitating pepsinogen secretion. In the present study, we investigated whether PAR-1, a thrombin receptor, could modulate pepsinogen secretion in rats. The PAR-1-activating peptide TFLLR-NH(2) as well as the PAR-2-activating peptide SLIGRL-NH(2), administered i.v. repeatedly at 1-h intervals, significantly increased gastric pepsinogen secretion over 2-4 h (after two to four doses). In contrast, the control peptide FTLLR-NH(2), given in the same manner, had no such effect. Thus, PAR-1, like PAR-2, might function to facilitate pepsinogen secretion, suggesting a novel role of the thrombin-PAR-1-pathway in the stomach.

PAR-2 modulates pepsinogen secretion from gastric-isolated chief cells

In the present study, we investigated whether activation of protease-activated receptor type 2 (PAR-2) with SLIGRL (SL)NH2, a short mimetic agonistic peptide, directly stimulates pepsinogen secretion from gastric-isolated, pepsinogen-secreting (chief) cells. Immunostaining of gastric-dispersed chief cells with a specific anti-PAR-2 antibody demonstrated expression of PAR-2 receptors on membrane and cytoplasm. SL-NH2 and trypsin potently stimulated pepsinogen secretion (EC50 = 0.3 nM) and caused Ca2+ mobilization (EC50 = 0.6 nM). In contrast to SL-NH2, the scramble peptide LSIGRL-NH2 failed to stimulate pepsinogen release. Exposure to SL-NH2 also resulted in ERK1/2 phosphorylation and activation. Exposure of chief cells to phosphotyrosine kinase inhibitors and 2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one, a selective MEK inhibitor, significantly reduced secretion induced by SL-NH2. Pepsinogen secretion induced by SL-NH2 was desensitized by pretreating the cells with the mimetic peptide and trypsin, and exposure to SL-NH2 abrogates pepsinogen secretion induced by carbachol and CCK-8, but not secretion induced by secretin and vasointestinal peptide. Exposure to Arg-Pro-Lys-Pro-Gln-Gln-Phe-Phe-Gly-Leu-Met-NH2 (substance P) but not to calcitonin gene-related peptide increased pepsinogen release. The neurokinin-1 receptor antagonist, N-acetyl-l-tryptophan 3,5-bis(trifluoromethyl)benzyl ester, inhibited substance P-stimulated pepsinogen secretion, whereas it did not affect secretion induced by SL-NH2. Collectively, these data indicate that PAR-2 is expressed on gastric chief cells and that its activation causes a Ca2+-ERK-dependent stimulation of pepsinogen secretion.

Pepsinogen A, pepsinogen C, and gastrin as markers of atrophic chronic gastritis in European dyspeptics

Serum levels of pepsinogen and gastrin are parameters that can be used as biomarkers for gastric mucosa. The aim of this study was to validate these serum biomarkers, that is pepsinogen A (PGA), pepsinogen C (PGC), PGA/PGC ratio, and gastrin, as screening tests for precancerous lesions: atrophic chronic gastritis (ACG) or Helicobacter pylori-related corpus-predominant or multifocal atrophy. The study population was comprised of a subsample of 284 patients from the 451 included in the Eurohepygast cohort, between 1995 and 1997. The concentrations of PGA, PGC, and gastrin were measured by radioimmunoassays. Histological diagnosis was the gold standard. Cut-off points were calculated using receiving operator characteristics (ROC) curves. Factors linked to variation of biomarkers were identified using multivariate linear regression. The mean of each biomarker in the sample was: PGA, 77.4 microg x l(-1); PGC, 13.2 microg x l(-1); PGA/PGC, 6.7; and gastrin, 62.4 ng x l(-1). For ACG patients, the areas under the PGA, PGC, PGA/PGC, and gastrin ROC curves were 0.55, 0.62, 0.73, and 0.58, respectively. The best cut-off point for PGA/PGC was 5.6, with sensitivity 65% and specificity 77.9%. For H. pylori-related corpus-predominant or multifocal atrophy, the areas under the respective ROC curves were 0.57, 0.67, 0.84, and 0.69. The best cut-off point for PGA/PGC was 4.7, with sensitivity 77.1% and specificity 87.4%. The results suggested that only the PGA/PGC ratio can be considered as a biomarker for precancerous lesions of the stomach, and may be useful as a screening test.

Versatile roles for sonic hedgehog in gut development

Sonic hedgehog (Shh) is a gene encoding a protein that can be secreted and act as a morphogen. The protein exerts versatile and important effects on the surrounding cells by binding a specific receptor, named patched. So far Shh has been shown to be involved in the morphogenesis and cytodifferentiation of many organ systems, such as notochord, floor plate, limb, pancreas, and pituitary gland, to mention only a few examples. Shh is also involved in the determination of left-right asymmetry, at least in the chicken embryo. Here we present evidence that Shh is one of the key genes whose activity is pivotal for the normal morphogenesis and differentiation of digestive organs. Epithelial Shh regulates the formation of stomach glands and stratification of the mesenchyme into connective tissue and smooth muscle. It exerts its effect often through the induction of bone morphogenetic protein (BMP) genes in the mesenchyme. Thus, Shh is a key player in the epithelial-mesenchymal interactions in the development of the gut.

[PAR (protease-activated receptor) as a novel target for development of gastric mucosal cytoprotective drugs]

Protease-activated receptor-2 (PAR-2), a G protein-coupled seven trans-membrane domain receptor, is distributed throughout the gastrointestinal tract, modulating various functions. In gastric mucosa, PAR-2 present in sensory neurons, upon activation, triggers mucus secretion by stimulating release of CGRP and tachykinins, resulting mucosal cytoprotection. PAR-2 activation also suppresses acid secretion and increase mucosal blood flow, contributing to the protective mechanisms. In contrast, PAR-2 is also present in chief cells, facilitating pepsinogen secretion. PAR-2 would thus appear to be primarily protective in gastric mucosa, but may also have an aggressive property in certain conditions. Finally, functions of PARs other than PAR-2 in gastric mucosa are also discussed.

Soluble expression and purification of porcine pepsinogen from Pichia pastoris

This paper presents a new system for the soluble expression and characterization of porcine pepsinogen from the methylotrophic yeast Pichia pastoris. The cDNA that encodes the zymogenic form of porcine pepsin (EC 3.4.23.1) was cloned into the EcoRI site of the vector pHIL-S1 downstream from the AOX1 alcohol oxidase promoter. After P. pastoris transformation, colonies were screened for expression of pepsinogen based on enzyme activity of the active form, pepsin. The recombinant enzyme was purified 138-fold by anion exchange and affinity column chromatography. Homogeneity was confirmed through SDS-PAGE, Western blot, and N-terminal sequencing. When compared to commercial pepsin, the recombinant pepsin had similar kinetic profiles, pH/temperature stability, and secondary/tertiary conformation. A glycosylated form was also isolated and found to exhibit kinetic and structural characteristics similar to those of the commercial and wild-type pepsin, but was slightly more thermal stable. The above results indicate that the P. pastoris expression system offers a convenient and efficient means to produce and purify a soluble form of pepsin(ogen).

Independent variation in susceptibilities of six different mouse strains to induction of pepsinogen-altered pyloric glands and gastric tumor intestinalization by N-methyl-N-nitrosourea

Strain differences in susceptibility regarding stomach carcinogenesis due to N-methyl-N-nitrosourea were examined in males of six strains of mice: BALB/cA (BALB), C57BL/6N (C57BL6), CBA/JN (CBA), C3H/HeN (C3H), DBA/2N (DBA/2), and CD-1 (ICR). The frequency of pepsinogen-altered pyloric glands (PAPGs), putative precancerous lesions, was highest (19.6+/-9.9%) in the BALB and lowest in the ICR (12.3+/-5.7%) mice (P<0.05). Incidences of adenocarcinomas at week 52 were 59.3% (16 of 27) and 18.5% (5 of 27), respectively (P<0.005). Invasion also tended to be deepest in BALB compared with the other strains. Intestinal alkaline phosphatase-positive intestinal type cells were observed heterogeneously in some hyperplasias, adenomas and adenocarcinomas consisting of gastric type cells. Thus, intestinalization appeared to occur at random in both non-neoplastic and monoclonal neoplastic lesions, making it unlikely that IAP-positive cells could be precursors of gastric tumors. In contrast, the data suggest a direct histogenetic role for the PAPG, a useful preneoplastic marker lesion in mouse strains.