Hypergastrinemia is associated with an increased risk of gastric adenocarcinoma with proximal location: A prospective population-based nested case-control study

The incidence of proximal gastric adenocarcinoma is increasing among younger adults. Rodent models have shown that hypergastrinemia causes carcinogenesis in the proximal stomach. The aim of our study was therefore to assess if hypergastrinemia was associated with an increased risk of developing gastric adenocarcinoma also in humans. A prospective population‐based nested case‐control study within the Nord‐Trøndelag Health Study (HUNT) cohort, Norway, was used to assess this association. Serum was collected from 78 962 participants in 1995 to 1997 and 2006 to 2008. In the cohort, 181 incident gastric adenocarcinoma cases were identified from the Norwegian Cancer and Patient Registries through 2015 and matched with 359 controls. The risk of gastric adenocarcinoma was compared between participants with prediagnostic hypergastrinemia (>60 pmol/L) and normal serum gastrin (≤60 pmol/L). Logistic regression provided odds ratios (ORs) with 95% confidence intervals (CIs), adjusted for body mass index, tobacco smoking and comorbidity. Hypergastrinemia was associated with increased risk of gastric adenocarcinoma overall (OR 2.2, 95% CI 1.4‐3.4) and in particular for gastric adenocarcinoma with proximal location (OR 6.1, 95% CI 2.7‐13.8), but not with gastric adenocarcinoma with distal location (OR 1.7, 95% CI 0.9‐3.4). Moreover, hypergastrinemia was associated with an increased risk of gastric adenocarcinoma of intestinal histological type (OR 3.8, 95% CI 1.8‐7.9), but not for diffuse histological type (OR 1.6, 95% CI 0.7‐3.7). In conclusion, hypergastrinemia was associated with an increased risk of proximal and intestinal type gastric adenocarcinoma.

What's new?

The incidence of proximal gastric adenocarcinoma has been reported to increase among younger adults in Western countries. Rodent models have shown that serum gastrin levels above the normal range cause carcinogenesis in the proximal stomach. In this first prospective population‐based study on the association between hypergastrinemia and gastric adenocarcinoma, the risk of gastric adenocarcinoma in the proximal stomach, but not in the distal stomach, was markedly increased in hypergastrinemic individuals. The finding supports the hypothesis that hypergastrinemia mediates the development of gastric adenocarcinoma in the proximal stomach, where mucosal proliferation is stimulated by gastrin.

Expression of Toll-like receptor-3 is enhanced in active inflammatory bowel disease and mediates the excessive release of lipocalin 2

Anti-microbial peptides might influence the pathogenesis and course of inflammatory bowel disease (IBD). We sought to clarify the role of the anti-microbial glycoprotein lipocalin 2 (LCN2) in the colon by determining its localization and regulation in IBD. Following a microarray gene expression study of colonic biopsies from a large IBD population (n = 133), LCN2 was localized using immunohistochemistry and in-situ hybridization. Moreover, we examined the regulation of LCN2 in HT-29 cells with a panel of pattern recognition receptors (PRRs) and sought evidence by immunohistochemistry that the most relevant PRR, the Toll-like receptor (TLR)-3, was indeed expressed in colonic epithelium in IBD. LCN2 was among the 10 most up-regulated genes in both active ulcerative colitis (UCa) and active Crohn's disease (CDa) versus healthy controls. LCN2 protein was found in both epithelial cells and infiltrating neutrophils, while mRNA synthesis was located solely to epithelial cells, indicating that de-novo synthesis and thus regulation of LCN2 as measured in the gene expression analysis takes place in the mucosal epithelial cells. LCN2 is a putative biomarker in faeces for intestinal inflammation, different from calprotectin due to its epithelial site of synthesis. LCN2 release from the colonic epithelial cell line HT-29 was enhanced by both interleukin (IL)-1β and the TLR-3 ligand poly(I:C), and TLR-3 was shown to be expressed constitutively in colonic epithelial cells and markedly increased during inflammation.

Treatment of gastric carcinoids type 1 with the gastrin receptor antagonist netazepide (YF476) results in regression of tumours and normalisation of serum chromogranin A

BACKGROUND

Patients with chronic atrophic gastritis have long-term gastric hypoacidity, and secondary hypergastrinaemia. Some also develop gastric ECL cells carcinoids (type 1 GC). Most type 1 GC remain indolent, but some metastasise. Patients undergo surveillance, and some are treated with somatostatin analogues, endoscopic resection or surgery. Netazepide (YF476) is a highly selective, potent and orally active gastrin receptor antagonist, which has anti-tumour activity in various rodent models of gastric neoplasia driven by hypergastrinaemia. Netazepide has been studied in healthy volunteers.

AIM

To assess the effect of netazepide on type 1 GC.

METHODS

Eight patients with multiple type 1 GC received oral netazepide once daily for 12 weeks, with follow-up at 12 weeks in an open-label, pilot trial. Upper endoscopy was performed at 0, 6, 12 and 24 weeks, and carcinoids were counted and measured. Fasting serum gastrin and chromogranin A (CgA) and safety and tolerability were assessed at 0, 3, 6, 9, 12 and 24 weeks.

RESULTS

Netazepide was well tolerated. All patients had a reduction in the number and size of their largest carcinoid. CgA was reduced to normal levels at 3 weeks and remained so until 12 weeks, but had returned to pre-treatment levels at 24 weeks. Gastrin remained unchanged throughout treatment.

CONCLUSIONS

The gastrin receptor antagonist netazepide is a promising new medical treatment for type 1 gastric carcinoids, which appear to be gastrin-dependent. Controlled studies and long-term treatment are justified to find out whether netazepide treatment can eradicate type 1 gastric carcinoids.

Gastric carcinoids after long-term use of a proton pump inhibitor

BACKGROUND

Proton pump inhibitors (PPIs) are potent inhibitors of gastric acid secretion and give hypergastrinemia secondary to gastric hypoacidity. PPI treatment therefore induces enterochromaffin-like (ECL) cell hyperplasia. Long-term hypergastrinemia in rodents and man also leads to ECL cell neoplasia. Whether long-term PPI treatment will induce ECL cell neoplasia in man has been disputed.

AIM

To describe gastric carcinoids in two patients with a history of long-term PPI use.

RESULTS

Two patients had been taking PPI for 12-13 years due to gastro-oesophageal reflux disease. At routine upper gastrointestinal endoscopy a solitary tumour was found in the oxyntic mucosa of both patients. Histology from the tumours showed in both cases a well-differentiated neuroendocrine tumour. Biopsies from flat oxyntic mucosa showed no signs of atrophic gastritis and a normal presence of parietal cells in both cases, but hyperplasia of ECL cells. The tumour in patient 1 was resected endoscopically. After cessation of PPI treatment the tumour regressed in patient 2 and the ECL cell hyperplasia regressed in both patients. In patient 2 serum gastrin and chromogranin A were elevated during PPI treatment, and normalised after cessation of treatment. In patient 1, unfortunately, we had serum only after treatment, and at that time both parameters were normal.

CONCLUSION

These cases show that hypergastrinemia secondary to proton pump inhibitors treatment, like other causes of hypergastrinemia, may induce enterochromaffin-like cell carcinoids in man.

Adipocytes express a functional system for serotonin synthesis, reuptake and receptor activation

AIMS

Serotonergic pathways in the central nervous system (CNS) are activated in the regulation of food intake and body weight. We hypothesized that adipocytes, like other cells of mesenchymal origin, possess serotonin receptors and thus could be regulated by peripherally circulating serotonin.

METHODS

In vivo studies: four Sprague-Dawley rats were given daily serotonin (5HT) injections subcutaneously (s.c., 25 mg/kg) for 5 days; four controls received saline. In a long-term study, 12 rats were given serotonin s.c. for 4 months, 10 controls received saline. Body weight was registered throughout the studies, and visceral adipose tissue and plasma were collected and analysed. Adipocytes were isolated from normal rat visceral abdominal adipose tissue and analysed for the expression of serotonin receptors, the serotonin transporter (5HTT/SERT), activation of serotonin synthesis (tryptophan hydroxylase 1, Tph1) and secretion and serotonin-induced leptin regulation by RT-PCR and protein analyses.

RESULTS

Hyperserotoninergic rats had significantly lower body weight (-7.4 and -6.8%) and plasma leptin levels (-44 and -38%) than controls, after both short- and long-term serotonin treatment, respectively, whereas plasma ghrelin levels were unaffected. Compared to controls, serotonin induced a 40-fold upregulation of 5HTT mRNA in visceral adipose tissue after 5 days of treatment. In vitro experiments showed that adipocytes express serotonin receptors, Tph1 and 5HTT, synthesize and secrete serotonin and that serotonin regulates leptin in mature adipocytes.

CONCLUSIONS

These findings show that serotonin may regulate adipocyte function in a direct manner via the blood circulation and/or paracrine and autocrine mechanisms, and not only indirectly via the CNS as previously assumed.

Serotonin and fluoxetine modulate bone cell function in vitro

Recent studies have proposed a role for serotonin and its transporter in regulation of bone cell function. In the present study, we examined the in vitro effects of serotonin and the serotonin transporter inhibitor fluoxetine "Prozac" on osteoblasts and osteoclasts. Human mononuclear cells were differentiated into osteoclasts in the presence of serotonin or fluoxetine. Both compounds affected the total number of differentiated osteoclasts as well as bone resorption in a bell-shaped manner. RT-PCR on the human osteoclasts demonstrated several serotonin receptors, the serotonin transporter, and the rate-limiting enzyme in serotonin synthesis, tryptophan hydroxylase 1 (Tph1). Tph1 expression was also found in murine osteoblasts and osteoclasts, indicating an ability to produce serotonin. In murine pre-osteoclasts (RAW264.7), serotonin as well as fluoxetine affected proliferation and NFkappaB activity in a biphasic manner. Proliferation of human mesenchymal stem cells (MSC) and primary osteoblasts (NHO), and 5-HT2A receptor expression was enhanced by serotonin. Fluoxetine stimulated proliferation of MSC and murine preosteoblasts (MC3T3-E1) in nM concentrations, microM concentrations were inhibitory. The effect of fluoxetine seemed direct, probably through 5-HT2 receptors. Serotonin-induced proliferation of MC3T3-E1 cells was inhibited by the PKC inhibitor (GF109203) and was also markedly reduced when antagonists of the serotonin receptors 5-HT2B/C or 5-HT2A/C were added. Serotonin increased osteoprotegerin (OPG) and decreased receptor activator of NF-kappaB ligand (RANKL) secretion from osteoblasts, suggesting a role in osteoblast-induced inhibition of osteoclast differentiation, whereas fluoxetine had the opposite effect. This study further describes possible mechanisms by which serotonin and the serotonin transporter can affect bone cell function.

A patient with Cronkhite-Canada syndrome, myxedema and muscle atrophy

A case of Cronkhite-Canada syndrome is presented. The patient had alopecia, onychodystrophy and gastrointestinal polyposis, mainly in the stomach and duodenum, with transient diarrhea and hypoproteinemia. Marked atrophy and weakness of the shoulder girdle muscles due to myopathy were also present. In addition she had primary hypothyroidism. The outcome of the disease is usually fatal within months, but so far our patient is alive four years after the onset of symptoms. The pathological changes, pathophysiology, symptoms, course and treatment of this rare disorder of unknown etiology are discussed.

Amylase, pancreatic isoamylase and lipase in serum before and after endoscopic pancreatography

Serum amylase, isoamylase and lipase were determined in 17 patients with pancreatic or biliary diseases before and after endoscopic retrograde pancreatography (ERP). Within 1/2-2 hours after cannulation of the pancreatic duct, serum lipase was increased to approximately 4 times the upper reference level and normalized almost completely at 24 hours. A much smaller increase was found in amylase and isoamylase. The elevation in enzyme activities was less in patients with abnormal than with normal ERP. The results suggest that lipase is a more sensitive indicator of pancreatic injury than amylase and isoamylase.

Long slender cytoplasmic extensions: a common feature of neuroendocrine cells?

We have recently developed a new method for visualisation of gut mucosal cells and demonstrated that enterochromaffin (EC) and enterochromaffin-like (ECL) cells possess cytoplasmic extensions. The aim of the present study was to characterise the morphology of D- and G-cells. The D-cells in the stomach differed morphologically from intestinal D-cells, suggesting two distinct subpopulations of D-cells. Some D-cells appeared to be interconnected. No cell-to-cell contact between parietal and D-cells was found. Both D- and G-cells possessed long cytoplasmic extensions corresponding with our previous descriptions of EC and ECL cells. We propose that all neuroendocrine cells have the ability to develop cytoplasmic extensions, enabling them to signal to their target cells in a neurocrine manner.

Neuroendocrine cells in pancreatic duct adenocarcinoma: an immunohistochemical study

Pancreatic ductal adenocarcinomas can display disseminated neuroendocrine (NE) cells. Controversies exist as to their relative incidence, histogenesis, hormone production, and the prognostic implications of their presence. These issues were elucidated by means of a broad immunohistochemical (IHC) investigation of the resected specimens from 47 patients. Chromogranin A (CgA) was chosen as the major NE marker. In addition, the sensitivity of the conventional IHC procedure was increased by means of the TSA (Tyramide Signal Amplification) technique. In tumours with CgA immunoreactive (IR) cells, detected by the conventional or the TSA methods, these NE cells were further IHC analyzed, using antisera raised against a broad spectrum of neurohormonal peptides, serotonin, and IGF-1. The IHC observations were correlated with clinical and histopathological data, the nuclear IR for the Ki67 antigen (proliferation) of the neoplastic cells, and their IR against the p53 protein. Distinct CgA IR cells were found in 5 out of 47 (11%) tumours when studied by the conventional method, and in 9 out of 47 (19%) when examined by the TSA technique. Corresponding figures, if tumours with only questionable IR against CgA were also included, were 14 (30%) and 23 (50%), respectively. Out of the 9 cases with unequivocal CgA IR, only 3 displayed an IR to an additional hormone or growth factor; this hormone turned out to be somatostatin (only minimal foci). Insulin and glucagon cells also appeared exceptionally. The NE differentiation was found to be unrelated to proliferation, p53 protein expression, and to the survival of the patients. It occurred mainly (7 out of 9) in poorly differentiated adenocarcinomas. Thus, the plain NE immunoprofile of the CgA IR cells, together with the increased IR observed when the TSA technique was used, indicates that the NE cells in these adenocarcinomas are only poorly differentiated. When the CgA IR cells exceptionally become highly differentiated, they can express islet hormones. Using strict structural and IHC criteria, a NE differentiation occurs in less than 20 % of cases; its clinico-pathological significance seems to be non relevant.

Increased serum levels of chromogranin A in male smokers with airway obstruction

The neuroendocrine (NE) system may play an important role in smoking-induced airway diseases. The aim of the present study was to examine the relationship between serum levels of the general NE marker chromogranin A (CgA) and smoking habits, respiratory symptoms and lung function. The study population consisted of never-smokers with normal lung function, smokers with normal lung function and smokers with airway obstruction who were randomly selected from the lung study of the Nord-Trøndelag Health Study (HUNT). Serum CgA was determined in 151, 138 and 116 subjects, respectively. All subjects were seronegative for Helicobacter pylori. Male smokers with airway obstruction had significantly higher serum CgA levels (median 3.70 nmol x L(-1) (interquartile range 3.10-5.15)) than both smokers with normal lung function (3.00 nmol x L(-1) (2.50-3.67)) and never-smokers with normal lung function (2.90 nmol x L(-1) (2.57-3.30)). The elevated levels of CgA correlated with the degree of airway obstruction. Moreover, the presence of respiratory symptoms and chronic bronchitis among male smokers were associated with increased serum CgA levels. Females had CgA levels similar to male smokers independent of smoking status and lung function. Elevated serum chromogranin A levels in subjects with airway obstruction and respiratory symptoms may represent neuroendocrine activation in inflammatory or remodelling processes in the lung.

Gene expression analysis and clinical diagnosis

BACKGROUND

A new basis for diagnostic tests is being provided by the vast amount of data on gene expression that are now becoming available through large-scale measurement of mRNA abundance. The insights gained from these resources are most likely going to provide both a better basic understanding of disease mechanisms, and to identify molecular markers for more precise diagnoses and for prediction of prognosis and treatment response.

METHODS

Some quantitative RT-PCR assays are utilized today for diagnosis of both malignant and non-malignant disease, but the use of gene expression measurements in clinical medicine can be expected to increase dramatically.

CONCLUSIONS

There are important technical issues that must be adequately solved in order to obtain robust assays, such as standardized protocols with appropriate quality controls that ensure reliable data for the specific samples being analysed and good inter-laboratory reproducibility.

ECL cell histamine mobilization and parietal cell stimulation in the rat stomach studied by microdialysis and electron microscopy

AIM

Gastrin stimulates acid secretion by mobilizing histamine from enterochromaffin-like (ECL) cells that occur predominantly at the base of the gastric glands. The parietal cells occur higher up in the glands nearer to the gastric lumen. The present study was performed to assess whether histamine is transported from the ECL cell via the microcirculation (endocrine route) or local diffusion (paracrine route).

METHODS

Totally isolated, vascularly perfused, rat stomachs were examined both in basal and gastrin-stimulated state. Histamine concentrations, determined by radioimmunoassay in venous effluent and microdialysate from an indwelling probe in the submucosa, were monitored over a period of 240 min. Gastrin-17 was infused through an arterial catheter for 120 min. The parietal cells were examined by electron microscopy, and the percentage of actively secreting parietal cells (displaying secretory canaliculi) in four regions along the glands (basal to surface, zones I-IV) was determined.

RESULTS

Gastrin stimulated acid secretion and histamine release as well as parietal cell activation. Upon gastrin stimulation, histamine concentration in the microdialysate was 2.5-fold higher than in the venous effluent (P = 0.008). The parietal cells in the upper part of the gland (zone III) were found to be activated the most.

CONCLUSION

As the histamine concentrations were higher in the tissue (microdialysate) than in blood, histamine seems to reach the parietal cells via the paracrine route. The fraction of active parietal cells seems to depend more on the age of the parietal cells than on the distance from the ECL cell.

One-year follow-up study of patients with enterochromaffin-like cell carcinoids after treatment with octreotide long-acting release

OBJECTIVE

In a one-year study of 5 patients with chronic atrophic gastritis (CAG), pernicious anaemia (PA), hypergastrinaemia and enterochromaffin-like (ECL) cell tumours, the somatostatin analogue octreotide LAR (long-acting release) in a dose of 20 mg given intramuscularly at monthly intervals had an antiproliferative effect on the ECL cells. The aim of the present study was to follow neuroendocrine (NE) markers in the blood and macroscopic and histopathological changes in the stomach during a 12-month follow-up after discontinuation of octreotide LAR treatment.

MATERIAL AND METHODS

Five patients underwent upper gastrointestinal endoscopy at 6 and 12 months' follow-up after octreotide LAR treatment. Biopsies from flat, oxyntic mucosa and from tumours were obtained. Sections were stained with haematoxylin-erythrosin and immunostained for the NE cell marker chromogranin A (CgA). Serum gastrin and CgA were measured every 3 months.

RESULTS

The number of visible tumours was unchanged (7) at 12 months' follow-up. One lesion showed carcinoid tumour and the others various degrees of linear and micronodular NE hyperplasia. At the same time-point, biopsies from flat, oxyntic mucosa showed a slightly (non-significant) elevated number of CgA immunoreactive (IR) cells. Serum gastrin increased from 186+/-50 pM (mean+/-SEM) to 603+/-109 pM (normal < 40 pM); p<0.05, and serum CgA increased non-significantly from 25+/-2 ng/ml (normal < 30 ng/ml) to 61+/-11 ng/ml.

CONCLUSIONS

During follow-up, slightly elevated levels of serum CgA and CgA IR cells in the oxyntic mucosa, without significant recurrence of ECL cell carcinoids, were observed.

Somatostatin-receptor 2 (sst2)-mediated effects of endogenous somatostatin on exocrine and endocrine secretion of the rat stomach

Somatostatin is a potent inhibitor of gastric acid secretion. Its effects are mediated through five specific receptor subtypes (sst(1-5)), of which sst(2) is dominant on the enterochromaffin-like (ECL) cell and the parietal cell. To study the paracrine mechanisms of somatostatin, the sst(2)-specific antagonist PRL-2903 was used. Effects of PRL-2903 on acid secretion and release of histamine were studied in the totally isolated, vascularly perfused rat stomach. Further, the release of histamine and gastrin after bombesin, alone and in combination with PRL-2903, were studied. Results are presented as mean+/-standard error of the mean (s.e.m.). PRL-2903 concentration-dependently increased the venous histamine concentration from basal 55.6+/-7.5 to 367+/-114 nM at 50 microM PRL-2903. With 10 microM PRL-2903, venous histamine output increased from baseline 6.2+/-0.5 to 20.9+/-4.9 nmol h(-1); P=0.008. The combination of 520 pM gastrin and 10 microM PRL-2903 increased venous histamine output from 41.7+/-7.3 nmol h(-1) with gastrin alone to 95.2+/-9.8 nmol h(-1); P=0.016. Further, 10 microM PRL-2903 increased acid output from baseline 8.5+/-1.8 to 37.4+/-11 micromol h(-1); P=0.017. When combined with 10 microM ranitidine, PRL-2903 did not significantly stimulate acid secretion. Bombesin/PRL-2903 increased venous histamine concentration from 50.4+/-14.8 to 292+/-64.2 nM; P=0.008, and gastrin concentration from 38.6+/-13.1 to 95.8+/-20.3 pM; P=0.037. Endogenous somatostatin exerts a continuous restraint on histamine and gastrin release from the gastric mucosa and significantly reduces baseline acid secretion.

Rebound acid hypersecretion after long-term inhibition of gastric acid secretion

BACKGROUND

Rebound acid hypersecretion develops after the use of acid inhibitors.

AIM

To estimate the duration of hypersecretion and to elucidate the role of the enterochromaffin-like (ECL) cell in rebound acid hypersecretion.

METHODS

Patients waiting for anti-reflux surgery who had used a proton pump inhibitor daily > 1 year were included. All patients discontinued taking acid inhibiting drugs after the operation. Basal and pentagastrin stimulated acid output was measured at 4, 8, 16 and 26 weeks postoperatively. Oxyntic mucosal biopsies were collected before and 26 weeks after the operation for counting of histidine decarboxylase (HDC) immunoreactive cells. Serum chromogranin A (CgA) and gastrin were measured before and at 4, 8, 16 and 26 weeks after the operation.

RESULTS

Pentagastrin stimulated acid secretion was higher at 4 and 8 weeks than at 26 weeks after the operation. Gastrin and CgA were significantly reduced at 4 and 8 weeks, respectively. The number of HDC immunoreactive cells was reduced by 60% at 26 weeks postoperative.

DISCUSSION

Rebound acid hypersecretion lasts more than 8 weeks, but less than 26 weeks after long-term proton pump inhibition.

CONCLUSION

The findings indicate that not only the parietal cell mass, but also ECL cell mass and activity are involved in the mechanism of acid hypersecretion.

Hypergastrinaemia induced by partial corpectomy results in development of enterochromaffin-like cell carcinoma in male Japanese cotton rats

BACKGROUND

Among inbred female cotton rats (Sigmodon hispidus) 25%-50% of the animals develop spontaneous gastric carcinomas, whereas males have an incidence of less than 1%. The carcinomas are enterochromaffin-like (ECL)-cell derived. Animals with gastric carcinomas also have hypergastrinaemia and gastric hypoacidity, but the mechanism behind the hypoacidity is unknown. Carcinomas have been found in all female cotton rats with spontaneous hypergastrinaemia lasting more than 4 months, and a gastrin receptor antagonist prevents the development of carcinoma. The purpose of the present study was to investigate whether induced hypergastrinaemia in male cotton rats would also result in carcinomas.

METHODS

Hypergastrinaemia was induced by partial corpectomy of male cotton rats, aiming at removal of 80%-90% of the corpus. A control group was sham-operated.

RESULTS

All partially corpectomized animals developed persistent hypergastrinaemia. Six months after the operation, 9 out of 13 partially corpectomized animals developed gastric cancer. In the dysplastic mucosa surrounding the tumours there was an increase in chromogranin A immunoreactive cells, where numerous cells also were stained using the Sevier-Munger technique. Tumour tissue also contained cells that were chromogranin A positive and stained by Sevier-Munger.

CONCLUSIONS

ECL-cell carcinomas can be induced in male cotton rats by partial corpectomy. This supports a previous statement that spontaneous carcinomas in female cotton rats are caused by gastric hypoacidity and hypergastrinaemia. In hypergastrinaemic animals, ECL-cell carcinomas develop independently of gender within a relatively short period of time, and cotton rats therefore represent an interesting model for studying gastric carcinogenesis.

Clinical significance of elevated serum chromogranin A levels

BACKGROUND

Chromogranin A (CgA) has been shown to be a useful marker in the diagnosis of neuroendocrine (NE) tumours. The clinical significance of CgA has been studied mostly in patients with known NE tumours. The diagnosis was evaluated in 153 consecutive patients in whom CgA was measured in a given time interval.

METHODS

CgA in serum was measured by radioimmunoassay. Immunohistochemistry with an antibody against CgA was performed in tumours from patients with adenocarcinoma and elevated CgA levels using a conventional method and the more sensitive tyramide signal amplification (TSA) technique.

RESULTS

Elevated serum CgA levels were found in 44 patients; 19 had NE tumours and 6 had tumours classified as adenocarcinomas. With the TSA technique, a high proportion of CgA-positive cells were disclosed in five of the adenocarcinoma patients. Patients with atrophic gastritis (no. 2) and patients treated with inhibitors of gastric acid secretion (no. 6) also had elevated levels of CgA. A modest increase in CgA levels was observed in 2 patients with renal impairment, and in 9 patients without any obvious cause.

CONCLUSION

The current study confirms that serum CgA is a sensitive marker for the detection of NE neoplasia. Elevated levels found in patients with adenocarcinoma may indicate NE differentiation in the tumour. CgA is a useful tool in the monitoring of enterochromaffin-like (ECL) hyperplasia secondary to treatment with acid secretion inhibitors or atrophic gastritis.

Treatment of ECL cell carcinoids with octreotide LAR

BACKGROUND

Patients with chronic atrophic gastritis (CAG) and hypergastrinaemia are at risk of developing hyperplasia of the enterochromaffin-like (ECL) cells and ECL-cell-derived tumours. The effect of the somatostatin analogue octreotide on ECL cell carcinoids is examined.

METHODS

Five patients with hypergastrinaemia and ECL cell carcinoids were enrolled in a 1-year study of octreotide LAR (long-acting release) 20 mg given at monthly intervals. Biopsies from tumours and from flat oxyntic mucosa were done at the start and 3, 6 and 12 months thereafter. Sections were stained with haematoxylin-erythrosin, immunostained with chromogranin A (CgA) and doublestained with CgA and Ki-67. Serum gastrin and CgA were measured.

RESULTS

The number of visible tumours was reduced by more than 50 %. Sections from both tumours and flat mucosa showed a reduced number of CgA immunoreactive cells. Mean serum gastrin decreased from 421 to 186 pM (normal <40 pM); P > 0.05, and serum CgA from 73 to 25 ng/ml (normal < 30 ng/ml); P < 0.001.

CONCLUSIONS

During treatment the patients were still markedly hypergastrinaemic, whereas the serum CgA showed normalization. A diminished tumour load and reduced ECL cell density were found, indicating an antiproliferative effect of octreotide directly on the ECL cells.

Spontaneous enterochromaffin-like cell carcinomas in cotton rats (Sigmodon hispidus) are prevented by a somatostatin analogue

Among inbred female cotton rats (Sigmodon hispidus) 25-50% of the animals develop spontaneous gastric carcinomas; the corresponding figure for male cotton rats is approximately 1%. Animals with carcinomas have hypergastrinaemia and gastric hypo-anacidity and the tumours are derived from enterochromaffin-like (ECL) cells. The mechanism behind the hypo-anacidity is unknown. Carcinomas are found in all female cotton rats with hypergastrinaemia lasting more than 4 months and this represents an excellent animal model for studying gastric carcinogenesis. In this study, the somatostatin analogue octreotide was given to female cotton rats to prevent carcinoma development caused by hypergastrinaemia. Twelve female cotton rats were given monthly injections of long-acting octreotide (5 mg i.m.) for 6 months. A control group of 20 animals was not given injections. Of the 20 control animals, 13 developed hypergastrinaemia and histologically invasive carcinomas or dysplasia. Of the 12 animals in the octreotide group, five developed hypergastrinaemia. None of these five animals developed histological cancer (P<0.05), whereas three had dysplasia. However, octreotide did not affect plasma gastrin concentration or antral gastrin mRNA abundance significantly. Dysplasia of the oxyntic mucosa in hypergastrinaemic animals was accompanied by a marked increase in chromogranin A-immunoreactive cells and cells positive for Sevier-Munger staining. The malignant tissue also contained groups of cells with Sevier-Munger staining. In conclusion, octreotide prevented ECL cell carcinomas in hypergastrinaemic cotton rats without lowering the gastrin concentration.

Cytotoxicity of streptozotocin on neuroendocrine cells of the pancreas and the gut

Streptozotocin has been used to induce diabetes mellitus in experimental animals and has been thought to have a selective cytotoxic effect on the beta-cells in the islets of Langerhans. The aim of the present study was to determine whether streptozotocin has any cytotoxic effect on other neuroendocrine cells of the gastrointestinal tract. Eight female Sprague-Dawley rats received intraperitoneal injections of 100 mg/kg streptozotocin in citric acid buffer; the concentration of streptozotocin was adjusted to 25 mg/ml buffer. Seven rats, serving as controls, received an equivalent volume of the vehicle. The rats were killed after three days and the fundus, antrum, small intestine and pancreas were examined for neuroendocrine cells. Our study confirms that streptozotocin is cytotoxic towards beta-cells. In addition, it is cytotoxic towards neuroendocrine cells of the oxyntic mucosa of the stomach. This finding may have clinical significance and suggests that streptozotocin may be used in the treatment of gastric neuroendocrine tumors as well as insulinomas.

Neuroendocrine differentiation in carcinoma of the breast. Tyramide signal amplification discloses chromogranin A-positive tumour cells in more breast tumours than previously realized

The aim of the study was to determine if, by means of tyramide signal amplification (TSA), the presence of chromogranin A (CgA)-positive tumour cells could be demonstrated in breast cancer cases found to be negative by conventional immunohistochemical staining. Sections from 44 cases of breast cancer (28 infiltrating ductal carcinomas, 2 lobular carcinomas, 4 ductal carcinomas in situ (DCIS), 7 lobular carcinomas in situ (LCIS), and 3 mucinous carcinomas) were stained for CgA by conventional immunohistochemical methods and by immunohistochemistry with TSA. The sections were also histologically graded and their oestrogen receptor (ER), progesterone receptor (PgR) and HER-2 oncogene status was recorded. Five of the tumours showed CgA-positive staining with the polyclonal antibody 430 with conventional methods. Thirty cases showed CgA-immunoreactive tumour cells after immunohistochemical staining with the polyclonal antibody 430 with TSA. However, eight of these also showed faint staining with the negative control antibody X0936 with TSA. One case showed immunopositivity for CgA using a monoclonal antibody without tyramide amplification and only a further two cases were positive when TSA was applied. The presence of CgA appears to be associated with a lower histological grade and may be more often found in oestrogen receptor-positive tumours.

Effects of anaesthetic agents on gastrin-stimulated and histamine-stimulated gastric acid secretion in the totally isolated vascularly perfused rat stomach

BACKGROUND

Anaesthetic agents affect gastric acid secretion, but the mechanisms behind this action have not been fully evaluated. The enterochromaffin-like (ECL) cell plays a key role in the regulation of gastric acid secretion, and anaesthetic agents have recently been described as inhibiting histamine release from the ECL cell. The present study examines the effect of anaesthetic agents on the ECL cell and on parietal cell functions.

METHODS

Different concentrations of urethane, pentobarbital and a mixture of fluanisone/fantanyl/midazolam (FFM) were examined for the effect on gastrin-stimulated histamine release and acid secretion and on histamine-stimulated acid secretion in the totally isolated vascularly perfused rat stomach. The luminal acid output and histamine concentrations in venous effluents were measured by titration and radioimmunoassay, respectively.

RESULTS

Pentobarbital caused an inhibition on both histamine release and acid output in gastrin-stimulated stomachs in a concentration-dependent way. The mixture of FFM at higher concentrations inhibited histamine release from the ECL cell and luminal H+ output in gastrin-stimulated acid secretion. Urethane exerted a slight inhibitory effect on histamine release only at the lowest concentration. Pentobarbital also reduced histamine-stimulated gastric acid secretion, while the mixture of FFM did not.

CONCLUSIONS

pentobarbital inhibits acid secretion both by reducing ECL cell histamine release and parietal cell H+ secretion, whereas FFM inhibits acid secretion by interaction with the ECL cell only. Urethane also had a slight inhibitory effect on the ECL cell histamine release at the lowest concentration.

Gastric acidity protects mice against prion infection?

BACKGROUND

The transmissible degenerative encephalopathies (TDEs) constitute a distinct group of diseases (scrapie in sheep, bovine spongiform encephalopathy (BSE) and Creutzfeldt-Jakob disease (CJD) in humans). The causal agents are not fully characterized, but are known to be resistant to most inactivation procedures. Ruminants appear to be particularly susceptible to TDEs. The concentrations of hydrochloric acid in their digestive tracts are significantly lower than in monogastric species.

METHODS

The aim of the study was to examine the role of gastric acidity in the protection of mice against infection after intragastric administration of different doses of a scrapie agent. Gastric acidity levels in mice were reduced by adding ranitidine to the drinking water and the animals were observed for neurological symptoms and at sacrifice examined microscopically for spongiform lesions in the brain.

RESULTS

The lower doses of infectious material induced disease significantly more often in mice given ranitidine compared with the controls.

CONCLUSION

These data indicate that the normal levels of gastric acidity in mice protect them to some extent from infection with low doses of scrapie agent. This finding is potentially relevant to the pathogenesis of the variant form of CJD, which appears to be associated with the consumption of BSE-infected food products.

Glycine-extended gastrin-17 stimulates acid secretion only via CCK-2 receptor-induced histamine release in the totally isolated vascularly perfused rat stomach

The effects of gastrin precursors have been discussed during recent years. However, the mechanism for their action, whether through a novel receptor on the parietal cell or a cholecystokinin-2 (CCK-2) receptor on the enterochromaffin like (ECL) cells, is still not settled. This study examines the effect of glycine-extended gastrin-17 (Gly-G-17), the main non-amidated gastrin precursor, on gastric acid secretion and histamine release in the totally isolated vascularly perfused rat stomach. Glycine-extended gastrin-17 at the concentrations from 0.52 to 520 nmol L(-1) was administered to the totally isolated vascularly perfused rat stomach. Glycine-extended gastrin-17 at 52 or 520 nmol L(-1), and gastrin-17 at 0.52 nmol L(-1)were co-administered to examine whether glycine-extended gastrin augmented maximal gastrin stimulated acid secretion and histamine release. Both Gly-G-17 at 52 nmol L(-1) and gastrin-17 (G-17) at 0.52 nmol L(-1) were administered together with the histamine-2 receptor antagonist ranitidine at 10 micromol L(-1). Gastric acid and venous histamine output were measured. Glycine-extended gastrin-17 at lower concentrations from 0.52 to 5.2 nmol L(-1) did not stimulate gastric acid output or histamine release, whereas higher concentrations from 52 to 520 nmol L(-1) elicited a concentration-dependent increase in acid secretion and histamine release. The outputs of acid and histamine at 520 nmol L(-1) Gly-G-17 were at the same level as those found for G-17 at its maximally effective concentration of 0.52 nmol L(-1). Glycine-extended gastrin-17 at maximally effective concentration of 520 nmol L(-1) did not augment maximal gastrin stimulated acid secretion or histamine release. Ranitidine inhibited G-17 and Gly-G-17 stimulated acid secretion to a similar degree. This study confirms that the stimulatory effect of Gly-G-17 on gastric acid secretion is via a CCK-2 receptor on the ECL cell.

Hypergastrinemia as a cause of chromogranin a increase in blood in patients suspected to have neuroendocrine tumor

BACKGROUND

Chromogranin A (CgA) is a sensitive marker for neuroendocrine neoplasia. Enterochromaffin-like cell hyperplasia secondary to hypergastrinemia also leads to CgA increase in blood. Treatment with inhibitors of acid secretion, atrophic gastritis and infection with Helicobacter pylori are prevalent conditions leading to hypergastrinemia. We therefore wanted to study whether concomitant determination of gastrin could increase the utility of CgA as a marker of neuroendocrine neoplasia.

METHODS

CgA and gastrin concentrations were determined by radioimmunoassay methods, while pepsinogen I (used to diagnose severe atrophic gastritis) was determined by a commercial immunoenzymatic assay.

RESULTS

Among 100 patients with elevated CgA, we found that 29% had hypergastrinemia. Vice versa, CgA was elevated in 23 out of 26 (88.5%) in a population of patients with hypergastrinemia. By determining pepsinogen I in blood in patients with hypergastrinemia, a proportion of them was diagnosed as having severe atrophic gastritis.

CONCLUSION

We conclude that determination of gastrin in blood in patients with CgA elevation will increase the utility of CgA in the diagnosis of neuroendocrine tumors.

The CCK-2 receptor is located on the ECL cell, but not on the parietal cell

BACKGROUND

The interrelationship between histamine and gastrin in the physiological regulation of gastric acid secretion is still a matter of dispute. CCK-2 receptors are located on enterochromaffin-like (ECL) cells in corpus mucosa and gastrin stimulates acid production by releasing histamine from the ECL cells, which in turn stimulates the parietal cells. Whether parietal cells also possess gastrin receptors of physiological significance is unclear. The aim of the present study was to localize the CCK-2 receptor cellularly and concomitantly demonstrate a gastrin receptor response (histamine release).

METHODS

Fluorescein labelled cholecystokinin-8 (Fluo-CCK-8) was added to the arterial infusion to totally isolated, vascularly perfused rat stomachs to a final concentration of 130 pmol L(-1) for 1 min, either alone or along with 520 nmol(-1) CCK-8 after 10-min pre-perfusion with CCK-8. Immediately after the Fluo-CCK-8 had reached the oxyntic mucosa, biopsies were taken and the binding sites were localized by double immunohistochemistry combined with the tyramide signal amplification (TSA) technique. Venous histamine was measured before and during stimulation.

RESULTS

Fluo-CCK-8 (130 pM) evoked histamine release, and binding sites were found in the basal part of corpus mucosa, co-localized with histidine decarbocylase (HDC) immunoreactive ECL cells. No binding of Fluo-CCK was found in the mid-glandular region of corpus, dominated by parietal cells. Binding of Fluo-CCK-8 was abolished by concomitant perfusion with excess CCK-8.

CONCLUSION

Fluo-CCK-8 given to isolated rat stomachs in a physiological concentration binds to CCK-2 receptors on ECL cells and causes histamine release, whereas no binding of Fluo-CCK-8 to parietal cells was found.

PACAP stimulates gastric acid secretion in the rat by inducing histamine release

Previous studies have shown that pituitary adenylate cyclase-activating peptide (PACAP) stimulates enterochromaffin-like (ECL) cell histamine release, but its role in the regulation of gastric acid secretion is disputed. This work examines the effect of PACAP-38 on aminopyrine uptake in enriched rat parietal cells and on histamine release and acid secretion in the isolated vascularly perfused rat stomach and the role of PACAP in vagally (2-deoxyglucose) stimulated acid secretion in the awake rat. PACAP has no direct effect on the isolated parietal cell as assessed by aminopyrine uptake. PACAP induces a concentration-dependent histamine release and acid secretion in the isolated stomach, and its effect on histamine release is additive to gastrin. The histamine H2 antagonist ranitidine potently inhibits PACAP-stimulated acid secretion without affecting histamine release. Vagally stimulated acid secretion is partially inhibited by a PACAP antagonist. The results from the present study strongly suggest that PACAP plays an important role in the neurohumoral regulation of gastric acid secretion. Its effect seems to be mediated by the release of ECL cell histamine.

Long-term omeprazole treatment suppresses body weight gain and bone mineralization in young male rats

BACKGROUND

The stomach is rich in endocrine cells, including those producing ghrelin, which is thought to play a role in the control of body growth. Omeprazole treatment is associated with hypergastrinaemia, resulting in growth of the oxyntic mucosa in general and the enterochromaffin-like (ECL) cells in particular. In the present study, we examined the effects of long-term omeprazole treatment on young male rats with respect to body growth and stomach.

METHODS

Male rats (24 days old) were treated with omeprazole (400 micromol/kg/day) or vehicle for 77 days. The body weight was recorded twice per week. At sacrifice, dual-energy X-ray absorptiometry (DXA) was used to assess total bone area, bone mineral content (BMC), bone mineral density (BMD) and body composition (fat and lean body mass). The lengths of the spine and the femur were recorded. The plasma concentrations of gastrin and histamine were determined by radioimmunoassays. The endocrine cells of the stomach were examined by immunocytochemistry.

RESULTS

The body weight gain was suppressed by omeprazole treatment. The bone area, BMC and BMD were reduced, while the lengths of the spine and the femur and the body composition were unchanged. Omeprazole-induced hypergastrinaemia was associated with enlargement of the oxyntic area and with hyperplasia of ECL cells but not of A-like cells and D cells. In contrast, the enterchromaffin (EC) cell density in the antrum was reduced.

CONCLUSIONS

Omeprazole treatment of young male rats reduces body weight and bone mass gain. The densities of ECL cells in the oxyntic mucosa was increased and of the EC cells in the antral mucosa reduced.

Neuroendocrine differentiation in bronchial carcinomas of classic squamous-cell type: an immunohistochemical study of 29 cases applying the tyramide signal amplification technique

With regard to the cellular origin of bronchial squamous-cell carcinomas, there are some clinicopathologic and experimental data indicating a link between neuroendocrine (NE) bronchial tumors and the traditionally non-NE squamous-cell carcinomas. Against this background, 29 consecutively resected bronchial squamous-cell carcinomas were examined immunohistochemically (IHC) by means of the specific NE cell marker chromogranin A (CgA), using not only conventional IHC methods, but also the technique with increased sensitivity, offered by the tyramide signal amplification (TSA) procedure. Whereas none of the 29 tumors displayed CgA immunoreactive (IR) cells using the conventional IHC procedure, 10 were found to display a fine granular CgA IR in the neoplastic parenchymal cells using the TSA technique. This incidence is higher than previously reported. However, the CgA IR cells never formed any majority cell population of the neoplastic parenchyma; when present, most of them occurred as micronodules or larger confluent areas in the peripheral most undifferentiated parts of the carcinomatous sheets. Single CgA IR cells were detected only rarely in the spinocellular or keratinized areas. It can be speculated that the observations conform with the recently proposed hypothesis that there is a reservoir of NE progenitor cells in the bronchial mucosa capable of proliferation.

Functionally impaired, hypertrophic ECL cells accumulate vacuoles and lipofuscin bodies. An ultrastructural study of ECL cells isolated from hypergastrinemic rats

ECL cells in the oxyntic mucosa of stomach control gastric acid secretion by mobilizing histamine in response to gastrin. They respond to gastrin also with hypertrophy and hyperplasia. ECL cells exhibit functional impairment upon long-term gastrin stimulation. The impairment is manifested in a gradual decline of the activity of the histamine-forming enzyme per individual ECL cell and in a failure of gastrin to mobilize histamine. The mechanism behind this impairment is unknown. In the present study, rats were treated with the proton pump inhibitor pantoprazole for 45 days to induce sustained hypergastrinemia. The ECL cells were isolated from normogastrinemic and hypergastrinemic rats and size-separated from other mucosal cells by the elutriation technique. The total ECL cell number was twofold higher in hypergastrinemic rats than in normogastrinemic rats, and most of the cells appeared in elutriation fractions where large cells predominate. The ECL cells of the different fractions were analyzed by quantitative electron microscopy. Normal-sized ECL cells from hypergastrinemic rats displayed a reduced number of secretory vesicles (probably because of degranulation) compared with normal-sized ECL cells from normogastrinemic rats. Hypertrophic ECL cells from hypergastrinemic rats had an unchanged number of secretory vesicles, supporting the view that such cells fail to respond to gastrin with degranulation. Although both normal-sized and hypertrophic ECL cells from hypergastrinemic rats contained vacuoles, those in the hypertrophic ECL cells were larger and more numerous. In addition, hypertrophic ECL cells were found to contain numerous, prominent lipofuscin bodies which are the presumed end product of crinophagia. Conceivably therefore, large vacuoles and lipofuscin bodies cause functional impairment of the hypertrophic ECL cells.

[Treatment of esophageal varices with banding ligation]

BACKGROUND

Randomised trials have shown that banding ligation is superior to sclerotherapy, requiring fewer treatment sessions to achieve variceal eradication, and giving lower rebleeding and complication rates.

MATERIAL AND METHODS

From November 1997 through December 1999, we have treated 22 patients with bleeding oesophageal varices with endoscopic banding ligation to obliterate the varices and prevent recurrent bleeding.

RESULTS

A total of 72 banding procedures have been performed using rubber bands. The varices have been obliterated in 14 patients requiring a median of 3.5 (range 2-8) procedures, which is in good agreement with other published data. Twelve of these patients have been observed for a median of six (range 1-19) months without signs of recurrent bleeding. One patient had a bleeding four months after the last ligation procedure; the varices were obliterated six weeks before. One patient had a recurrent bleeding between the first and second banding procedure. One patient bled from an oesophageal ulcer caused by a rubber band two weeks after the procedure. Otherwise no serious complications occurred.

INTERPRETATION

On the basis of our own experiences and published studies, we propose that endoscopic banding ligation should be the method of choice for elective treatment of bleeding varices.

Detection of chromogranin A in human gastric adenocarcinomas using a sensitive immunohistochemical technique

Neuroendocrine cells are often disclosed in human gastric adenocarcinomas and may be recognised by their immunoreactivity towards chromogranin A. However, in dedifferentiated neuroendocrine tumour cells, the chromogranin A content may be reduced making it difficult to detect with conventional immunohistochemical methods. We therefore used a sensitive signal amplification technique in order to evaluate chromogranin A immunoreactivity and thus neuroendocrine differentiation in 40 gastric adenocarcinomas. Neuroendocrine cells were visualised by means of a monoclonal chromogranin A antibody and the avidin-biotin peroxidase complex technique, without and with addition of tyramide signal amplification. Double immunohistochemistry towards chromogranin A and Ki-67 were used to disclose proliferation in the neoplastic cells. A marked increase in the number of carcinomas containing chromogranin A-immunoreactive neoplastic cells was noted when applying the tyramide signal amplification technique. In addition, the number of immunoreactive cells within each tumour increased, and in some cases almost all the neoplastic cells became immunoreactive. Chromogranin A-immunoreactive tumour cells showing signs of proliferation were found in the majority of these carcinomas. In conclusion, we have disclosed widespread immunoreactivity towards chromogranin A in a proportion of gastric adenocarcinomas when enhancing the signal with tyramide signal amplification. Neuroendocrine differentiation is thus a common finding in gastric carcinomas when using sensitive methods.