Changing pattern of cytokeratin 7 and 20 expression from normal epithelium to intestinal metaplasia of the gastric mucosa and gastroesophageal junction

Immunohistochemical features of the gastrointestinal tract tumors

Gastrointestinal tract tumors include a wide variety of vastly different tumors and on a whole are one of the most common malignancies in western countries. These tumors often present at late stages as distant metastases which are then biopsied and may be difficult to differentiate without the aid of immunohistochemical stains. With the exception of pancreatic and biliary tumors where there are no distinct immunohistochemical patterns, most gastrointestinal tumors can be differentiated by their unique immunohistochemical profile. As the size of biopsies decrease, the role of immunohistochemical stains will become even more important in determining the origin and differentiation of gastrointestinal tract tumors.

Intestinal metaplasia -the effect of Acid on the gastric mucosa and gastric carcinogenesis-

This review concerns stem cells and their relation to intestinal metaplasia. When gastric regions of mice, Mongolian gerbils or several strains of rats were irradiated with a total dose of 20 Gy of X-rays given in two fractions, intestinal metaplasia was only induced in rats. In addition, it was greatly influenced by rat strain and sex. Alkaline phosphatase (ALP) positive metaplastic foci were increased by administration of ranitidine (H₂ receptor antagonist), crude stomach antigens or subtotal resection of the fundus and decreased by cysteamine (gastric acid secretion stimulator), histamine or removal of the submandibular glands. Recent studies have shown that Cdx2 transgenic mice with gastric achlorhydria develop intestinal metaplasia and that in men and animals, Helicobacterpylori (H. pyrlori) infection can cause intestinal metaplasias that are reversible on eradication. Our results combined with findings for H. pylori infection or eradication and transgenic mice suggest that an elevation in the pH of the gastric juice due to disappearance of parietal cells is one of the principal factors for development of reversible intestinal metaplasia. When different organs were transplanted into the stomach or duodenum, they were found to transdifferentiate into gastric or duodenal mucosae, respectively. Organ-specific stem cells in normal non-liver tissues (heart, kidney, brain and skin) also differentiate into hepatocytes when transplanted into an injured liver. Therefore, stem cells have a multipotential ability, transdifferentiating into different organs when transplanted into different environments. Finally, intestinal metaplasia has been found to possibly increase sensitivity to the induction of tumors by colon carcinogens of the 1,2-dimethylhydrazine (DMH), azoxymethane (AOM) or 2-amino-1-methyl-6-phenylimidazo[4.5-b]pyridine (PhIP) type. This carcinogenic process, however, may be relatively minor compared with the main gastric carcinogenesis process induced by N-methy1-N’-nitro-N-nitrosoguanidine (MMNG) or N-methylnitrosourea (MNU), which is not affected by the presence of intestinal metaplasia. The protocol used in these experiments may provide a new approach to help distinguish between developmental events associated with intestinal metaplasia and gastric tumors.

Structure and functions of keratin proteins in simple, stratified, keratinized and cornified epithelia

Historically, the term 'keratin' stood for all of the proteins extracted from skin modifications, such as horns, claws and hooves. Subsequently, it was realized that this keratin is actually a mixture of keratins, keratin filament-associated proteins and other proteins, such as enzymes. Keratins were then defined as certain filament-forming proteins with specific physicochemical properties and extracted from the cornified layer of the epidermis, whereas those filament-forming proteins that were extracted from the living layers of the epidermis were grouped as 'prekeratins' or 'cytokeratins'. Currently, the term 'keratin' covers all intermediate filament-forming proteins with specific physicochemical properties and produced in any vertebrate epithelia. Similarly, the nomenclature of epithelia as cornified, keratinized or non-keratinized is based historically on the notion that only the epidermis of skin modifications such as horns, claws and hooves is cornified, that the non-modified epidermis is a keratinized stratified epithelium, and that all other stratified and non-stratified epithelia are non-keratinized epithelia. At this point in time, the concepts of keratins and of keratinized or cornified epithelia need clarification and revision concerning the structure and function of keratin and keratin filaments in various epithelia of different species, as well as of keratin genes and their modifications, in view of recent research, such as the sequencing of keratin proteins and their genes, cell culture, transfection of epithelial cells, immunohistochemistry and immunoblotting. Recently, new functions of keratins and keratin filaments in cell signaling and intracellular vesicle transport have been discovered. It is currently understood that all stratified epithelia are keratinized and that some of these keratinized stratified epithelia cornify by forming a Stratum corneum. The processes of keratinization and cornification in skin modifications are different especially with respect to the keratins that are produced. Future research in keratins will provide a better understanding of the processes of keratinization and cornification of stratified epithelia, including those of skin modifications, of the adaptability of epithelia in general, of skin diseases, and of the changes in structure and function of epithelia in the course of evolution. This review focuses on keratins and keratin filaments in mammalian tissue but keratins in the tissues of some other vertebrates are also considered.

Differences in genetic instability and cellular phenotype among Barrett's, cardiac, and gastric intestinal metaplasia in a Japanese population with Helicobacter pylori

AIMS

Intestinal metaplasia is considered to be a precursor lesion in both Barrett's and intestinal-type gastric cancer. The aim was to clarify the differences in molecular pathology between specialized intestinal metaplasia (SIM) in Barrett's oesophagus (BO), cardiac (CIM) and gastric intestinal metaplasia (GIM).

METHODS AND RESULTS

Eighty-eight SIM cases with BO, 30 CIM cases and 52 GIM cases in patients with or without Helicobacter pylori infectionwere analysed for genetic instability and Das-1. Microsatellite instability and a loss of heterozygosity were evaluated at five microsatellite loci. The incidence of genetic instability was 55.7% in SIM, 40.0% in CIM and 23.1% in GIM, revealing a significant difference between SIM and GIM (P < 0.0005). For each microsatellite marker analysed, there were obvious differences in frequency among the three conditions. Das-1 reactivity was significantly higher in SIM than in CIM or GIM (P < 0.0001, both). Interestingly, both genetic instability and Das-1 reactivity in SIM showed a significantly higher incidence in patients with H. pylori infection than in those without (P < 0.005 and P < 0.01, respectively).

CONCLUSIONS

SIM is distinct from CIM and GIM, and the pathogenesis of SIM, like that of GIM, is associated to some degree with H. pylori infection in a Japanese population.

Expression of cytokeratins in Helicobacter pylori –associated chronic gastritis of adult patients infected with cagA+ strains: An immunohistochemical study

AIM: To investigate the expression of different cytokeratins (CKs) in gastric epithelium of adult patients with chronic gastritis infected with Helicobacter pylori (H pylori) cagA+ strains.

METHODS: The expression of CK 7, 8, 18, 19 and 20 was studied immunohistochemically in antral gastric biopsies of 84 patients. All the CKs were immunostained in cagA+H pylori gastritis (57 cases), non-H pylori gastritis (17 cases) and normal gastric mucosa (10 cases).

RESULTS: In cagA+ H pylori gastritis, CK8 was expressed comparably to the normal antral mucosa from surface epithelium to deep glands. Distribution of CK18 and CK 19 was unchanged, i.e. transmucosal, but intensity of the expression was different in foveolar region in comparison to normal gastric mucosa. Cytokeratin 18 immunoreactivity was significantly higher in the foveolar epithelium of H pylori-positive gastritis compared to both H pylori-negative gastritis and controls. On the contrary, decrease in CK19 immunoreactivity occurred in foveolar epithelium of H pylori-positive gastritis. In both normal and inflamed antral mucosa without H pylori infection, CK20 was expressed strongly/moderately and homogenously in surface epithelium and upper foveolar region, but in H pylori -induced gastritis significant decrease of expression in foveolar region was noted. Generally, in both normal antral mucosa and H pylori-negative gastritis, expression of CK7 was not observed, while in about half cagA+ H pylori-infected patients, moderate focal CK7 immunoreactivity of the neck and coiled gland areas was registered, especially in areas with more severe inflammatory infiltrate.

CONCLUSION: Alterations in expression of CK 7, 18, 19 and 20 together with normal expression of CK8 occur in antral mucosa of H pylori-associated chronic gastritis in adult patients infected with cagA+ strains. Alterations in different cytokeratins expression might contribute to weakening of epithelial tight junctions observed in H pylori-infected gastric mucosa.

Distinction between short-segment Barrett’s esophageal and cardiac intestinal metaplasia

AIM: To investigate the roles of mucin histochemistry, cytokeratin 7/20 (CK7/20) immunoreactivity, clinical characteristics and endoscopy to distinguish short-segment Barrett’s esophageal (SSBE) from cardiac intestinal metaplasia (CIM).

METHODS: High iron diamine/Alcian blue (HID/AB) mucin-histochemical staining and immunohistochemical staining were used to classify intestinal metaplasia (IM) and to determine CK7/20 immunoreactivity pattern in SSBE and CIM, respectively, and these results were compared with endoscopical diagnosis and the positive rate of gastroesophageal reflux disease (GERD) symptoms and H pylori infection. Long-segment Barrett’s esophageal and IM of gastric antrum were designed as control.

RESULTS: The prevalence of type III IM was significantly higher in SSBE than in CIM (63.33% vs 23.08%, P<0.005). The CK7/20 immunoreactivity in SSBE showed mainly Barrett’s pattern (76.66%), and the GERD symptoms in most cases which showed Barrett’s pattern were positive, whereas H pylori infection was negative. However, the CK7/20 immunoreactivity in CIM was gastric pattern preponderantly (61.54%), but there were 23.08% cases that showed Barrett’s pattern. H pylori infection in all cases which showed gastric pattern was significantly higher than those which showed Barrett’s pattern (63.83% vs 19.30%, P<0.005), whereas the GERD symptoms in gastric pattern were significantly lower than that in Barrett’s pattern (21.28% vs 85.96%, P<0.005).

CONCLUSION: Distinction of SSBE from CIM should not be based on a single method; however, the combination of clinical characteristics, histology, mucin histochemistry, CK7/20 immunoreactivity, and endoscopic biopsy should be applied. Type III IM, presence of GERD symptoms, and Barrett’s CK7/20 immunoreactivity pattern may support the diagnosis of SSBE, whereas non-type III IM, positive H pylori infection, and gastric CK7/20 immunoreactivity pattern may imply CIM.

Cytokeratin phenotyping does not help in distinguishing oesophageal adenocarcinoma from cancer of the gastric cardia

BACKGROUND

It is sometimes difficult to distinguish between cardia cancer and oesophageal cancer.

AIMS

To evaluate whether cytokeratin (CK) expression of the tumour can be of value in differentiating between the two tumour types.

METHODS

Consecutive patients with a malignant tumour in the oesophagus or stomach were recruited. Biopsy specimens were taken for routine haematoxylin and eosin staining. One tissue block with representative tissue was selected for immunohistochemical staining (CK7 and CK20).

RESULTS

Endoscopically located adenocarcinoma of the oesophagus was present in 84 patients (64 men, 20 women; mean age, 68 years; range, 44-91). Cancer located primarily in the gastric cardia was present in 63 patients (42 men, 21 women; mean age, 68 years; range, 42-88). The histological diagnosis was metastasis from a primary tumour outside the oesophagus or stomach in 19 patients. The patients were divided into three groups for the immunohistochemical analysis. Patients in group A had definite oesophageal cancer, group B patients had a definite carcinoma located in the gastric cardia, and group C patients had an obstructing tumour distal in the oesophagus at the level of the diaphragm, which could not be passed with the endoscope. Paraffin wax embedded material was available from 122 patients for immunostaining and CK analysis. There was no significant difference in expression or distribution of CK7 or CK20 in the three groups of patients.

CONCLUSION

CK phenotyping cannot distinguish between cancer arising from a Barrett's oesophagus and carcinoma originating in the gastric cardia.

On the origin of cardiac mucosa: A histological and immunohistoc-hemical study of cytokeratin expression patterns in the developing esophagogastric junction region and stomach

AIM To examine the fetal and neonatal esophagogastric junction region (EGJ) histologically for the presence of an equivalent to adult cardiac mucosa (CM); to study the expression patterns of all cytokeratins (CK) relevant to the EGJ during gestation; to compare the CK profile of the gestational and the adult EGJ; and to determine the degree of development in the adult EGJ histology and CK profile during gestation.

METHODS: Forty-eight fetal autopsy specimens of the EGJ were step-sectioned and stained with hematoxylin and eosin (H&E) to select sections showing the mucosal lining. Immunohistochemistry for CK5, 7, 8, 13, 18, 19, and 20 was performed. Antibody staining was then graded for location, intensity, and degree.

RESULTS: The distal esophagus was lined by simple columnar epithelium from 12-wk gestational age (GA). The proximal part of this segment consisted of mucus-producing epithelium, devoid of parietal cells. CK5 and 13 were present exclusively in multilayered epithelia and CK8, 18, and 19 predominantly in simple columnar epithelium. There were no differences in the frequencies of the co-ordinate CK7+/20+ and the CK7-/20- immunophenotypes between different locations. The prevalence of the CK7+/20- immunophenotype decreased, and that of the CK7-/20+ immunophenotype increased significantly from the distal esophagus to the distal stomach.

CONCLUSION: Fetal columnar-lined lower esophagus (fetal CLE) may be the equivalent and precursor of the short segments of columnar epithelium found in the distal esophagus of some normal adult subjects. Esophageal simple columnar epithelium without parietal cells (ESN) may be the precursor of adult CM. The similarities between the fetal and adult EGJ and stomach CK expression patterns support the conclusion that adult CM has an identifiable precursor in the fetus. This would then indicate that at least a part of the adult CM has a congenital origin.

The utility of cytokeratins 7 and 20 (CK7/20) immunohistochemistry in the distinction of short-segment Barrett esophagus from gastric intestinal metaplasia: Is it reliable?

Background

The purpose of the present correlative immunohistochemical study was to assess the utility of cytokeratin (CK7 and CK20) expression in the diagnosis of short-segment Barrett esophagus, particularly its efficacy in differentiating Barrett mucosa from intestinal metaplasia of the gastric cardia and corpus.

Methods

Two groups of endoscopic biopsy specimens were examined, including 20 endoscopic biopsy specimens of short-segment Barrett esophagus (Group A) and equal number exhibiting Helicobacter pylori associated intestinal metaplasia of the gastric cardia and corpus (Group B). All were investigated by immunohistochemistry using the standard ABC method for CK7 and CK20 expression. Fisher's exact test was used for statistical analysis of Barrett CK7/20 and gastric CK7/20 patterns between the groups.

Results

The anticipated pattern of reactivity in Barrett mucosa (CK7: strong diffuse positivity in superficial and deep glands; CK20: positivity in surface epithelium and superficial glands) was seen in 2 cases of Group A specimens. The expected gastric pattern (CK7: patchy immunostaining with variable involvement of deep glands; CK20: patchy immunostaining of superficial and deep glands in incomplete intestinal metaplasia / absence of CK7 immunoreactivity with strong CK20 staining in superficial and deep glands in complete intestinal metaplasia) was seen in 8 cases of Group B specimens. The respective sensitivity and false-negativity values of CK7/20 staining for Barrett pattern in Group A were 10% and 90%, respectively. These values for gastric pattern in Group B were 40% and 60%, respectively. The specificity and false-positivity values of both patterns were same (100% and 0%, respectively). There was no statistically significant difference for Barrett pattern between the two groups (P = 0.487), while the observation of gastric pattern was significantly higher in Group B than in Group A (P = 0.02).

Conclusions

We concluded that these hypothesized and recently applied diagnostic criteria involving CK7 and CK20 immunoreactivity are not reliable in distinguishing short-segment Barrett esophagus from intestinal metaplasia as seen in gastric cardia and corpus.