Gastric corpus mucin expression after partial gastrectomy, in relation to colonization with Helicobacter pylori

Skin transcriptome, tissue distribution of mucin genes and discovery of simple sequence repeats in crucian carp (Carassius auratus)

Crucian carp (Carassius auratus) is one of the major freshwater species and important food fish in China. Fish skin acts as the first line of defence against pathogens, yet its molecular and immune mechanism remains unclear. In this study, a de novo transcriptome assembly of C. auratus skin was performed with the Illumina Hiseq 2000 platform. A total of 49,154,776 clean reads were assembled, among which 60,824 (46.86%), 37,103 (28.59%), 43,269 (33.33%) unigenes were annotated against National Center for Biotechnology Information, Gene Onotology and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases, respectively. KEGG Orthology categories were significantly involved in immune system (20.50%), signal transduction (18.04%) and mucosal mucin genes (e.g., muc2, muc5AC, muc5B, muc17, muc18). The high expression of muc18 gene was observed in brain; that of muc2 in intestine; and that of muc5AC in skin, liver, spleen, intestine and muscle. Moreover, the potential 28,928 simple sequence repeats with the three most abundant dinucleotide repeat motifs (AC/GT, AG/CT, AT/AT) were detected in C. auratus. To authors' knowledge, this is the first report to describe the transcriptome analysis of C. auratus skin, and the outcome of this study contributed to the understanding of mucosal immune response of the skin and molecular markers in cyprinid species.

Alzheimer Disease Pathology-Associated Polymorphism in a Complex Variable Number of Tandem Repeat Region Within the MUC6 Gene, Near the AP2A2 Gene

We found evidence of late-onset Alzheimer disease (LOAD)-associated genetic polymorphism within an exon of Mucin 6 (MUC6) and immediately downstream from another gene: Adaptor Related Protein Complex 2 Subunit Alpha 2 (AP2A2). PCR analyses on genomic DNA samples confirmed that the size of the MUC6 variable number tandem repeat (VNTR) region was highly polymorphic. In a cohort of autopsied subjects with quantitative digital pathology data (n = 119), the size of the polymorphic region was associated with the severity of pTau pathology in neocortex. In a separate replication cohort of autopsied subjects (n = 173), more pTau pathology was again observed in subjects with longer VNTR regions (p = 0.031). Unlike MUC6, AP2A2 is highly expressed in human brain. AP2A2 expression was lower in a subset analysis of brain samples from persons with longer versus shorter VNTR regions (p = 0.014 normalizing with AP2B1 expression). Double-label immunofluorescence studies showed that AP2A2 protein often colocalized with neurofibrillary tangles in LOAD but was not colocalized with pTau proteinopathy in progressive supranuclear palsy, or with TDP-43 proteinopathy. In summary, polymorphism in a repeat-rich region near AP2A2 was associated with neocortical pTau proteinopathy (because of the unique repeats, prior genome-wide association studies were probably unable to detect this association), and AP2A2 was often colocalized with neurofibrillary tangles in LOAD.

Helicobacter pylori and gastric mucin expression: A systematic review and meta-analysis

AIM: To investigate the relationship between Helicobacter pylori (H. pylori) and mucin expression in gastric mucosa.

METHODS: English Medical literature searches were conducted for gastric mucin expression in H. pylori infected people vs uninfected people. Searches were performed up to December 31^th 2014, using MEDLINE, PubMed, EMBASE, Scopus, and CENTRAL. Studies comparing mucin expression in the gastric mucosa in patients positive and negative for H. pylori infection, were included. Meta-analysis was performed by using Comprehensive meta-analysis software (Version 3, Biostat Inc., Englewood, NJ, United States). Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated compared mucin expression in individual studies by using the random effects model. Heterogeneity between studies was evaluated using the Cochran Q-test, and it was considered to be present if the Q-test P value was less than 0.10. I² statistic was used to measure the proportion of inconsistency in individual studies, with I² > 50% representing substantial heterogeneity. We also calculated a potential publication bias.

RESULTS: Eleven studies, which represent 53 sub-studies of 15 different kinds of mucin expression, were selected according to the inclusion criteria. Every kind of mucin has been considered as one study. When a specific mucin has been studied in more than one paper, we combined the results in a nested meta-analysis of this particular mucin: MUC2, MUC6, STn, Paradoxical con A, Tn, T, Type 1 chain mucin, LeA, SLeA, LeB, AB-PAS, MUC1, and MUC5AC. The odds ratio of mucin expression in random analysis was 2.33, 95%CI: 1.230-4.411, P = 0.009, higher expression in H. pylori infected patients. Odds ratio for mucin expression in H. pylori positive patients was higher for MUC6 (9.244, 95%CI: 1.567-54.515, P = 0.014), and significantly lower for MUC5AC (0.447, 95%CI: 0.211-0.949, P = 0.036). Thus, H. pylori infection may increase MUC6 expression and decrease MUC5AC expression by 924% and 52%, respectively.

CONCLUSION: H. pylori inhibits MUC5AC expression in the gastric epithelium, and facilitates colonization. In contrast, increased MUC6 expression may help inhibiting colonization, using MUC6 antibiotics properties.

Role of mucin Lewis status in resistance to Helicobacter pylori infection in pediatric patients

BACKGROUND

Helicobacter pylori causes gastritis, peptic ulcer and is a risk factor for adenocarcinoma and lymphoma of the stomach. Gastric mucins, carrying highly diverse carbohydrate structures, present functional binding sites for H. pylori and may play a role in pathogenesis. However, little information is available regarding gastric mucin in children with and without stomach diseases.

MATERIALS AND METHODS

Expression of mucins and glycosylation was studied by immunohistochemistry on gastric biopsies from 51 children with and without H. pylori infection and/or peptic ulcer disease.

RESULTS

In all children, MUC5AC was present in the surface epithelium and MUC6 in the glands. No MUC6 in the surface epithelium or MUC2 was detected in any section. The Le(b) and Le(a) blood group antigens were present in the surface epithelium of 80% and 29% of children, respectively. H. pylori load was higher in Le(b) negative children than in Le(b) positive individuals (mean +/- SEM 17.8 +/- 3.5 vs 10.8 +/- 1.5; p < 0.05), but there was no correlation between Le(a) or Le(b) status and gastritis, nodularity, and gastric or duodenal ulcer (DU). Expression of sialyl-Le(x) was associated with H. pylori infection, and DU.

CONCLUSIONS

Mucin expression and glycosylation is similar in children and adults. However, in contrast to adults, pediatric H. pylori infection is not accompanied by aberrant expression of MUC6 or MUC2. Furthermore, the lower H. pylori density in Le(b) positive children indicates that H. pylori is suppressed in the presence of gastric mucins decorated with Le(b), the binding site of the H. pylori BabA adhesin.

H. pylori/NSAID--negative peptic ulcer--the mucin theory

The incidence of Helicobacter pylori (H. pylori) and non-steroidal anti inflammatory drug (NSAID)--negative peptic ulcer disease increases, especially in the Western world and in countries where H. pylori infection rate is low. For the diagnosis of "idiopathic ulcer" one should rule out, in addition to H. pylori infection and NSAID or aspirin therapy, also other drugs, other infectious agents, as well as malignant and benign rare diseases. The mucin unstirred layer keeps the pH above the mucosa stable, and prevents the enzymatic attack by pepsin. Inhibition of cyclo-oxygenase by NSAID and aspirin prevents mucin secretion and exposes the mucosa for toxic effect of acid and enzymes. There is also relationship between H. pylori and mucin that from one hand enables mucin invasion but on the other hand protects the gastric mucosa. Mucin genetic or epigenetic changes may be blamed for idiopathic peptic ulcer disease, but this hypothesis should be further investigated.

Effects of Helicobacter pylori infection on mucin expression in gastric carcinoma and pericancerous tissues

BACKGROUND

Helicobacter pylori infection is one of the major causes of human gastric carcinoma and can disturb the gastric mucosa barrier. Mucins have not only lubricating and protecting functions, but are also related to signal transduction, turnover of gastric epithelium and carcinogenesis of gastric mucosa. The aim of this study was to investigate the relationship between H. pylori infection and aberrant mucin expression in patients with gastric carcinoma.

METHODS

H. pylori infection was diagnosed by the Warthin-Starry staining method. Different kinds of mucins were detected using an immunohistochemical method.

RESULTS

Of 46 patients with gastric carcinoma, there were 26 patients who had H. pylori infection (56.5%). Of 21 pericancerous mucosas from the H. pylori-positive patients, 14 had MUC2 expression (66.7%), seven had strong MUC1 expression (+ + +) (33.7%), seven had strong MUC6 expression (+ + +) (33.3%), and five had strong MUC5AC expression (+ + +) (23.8%). In contrast, only six of 18 H. pylori-negative pericancerous mucosas had MUC2 expression (33.3%) (P < 0.05 compared with H. pylori-positive pericancerous mucosas), 12 had strong MUC1 expression (+ + +) in 16 H. pylori-negative pericancerous mucosas (75%) (P < 0.05), 11 had strong MUC6 expression (+ + +) in 16 H. pylori-negative pericancerous mucosas (68.8%) (P < 0.05), and 10 had strong MUC5AC expression (+ + +) in 14 H. pylori-negative pericancerous mucosas (71.4%) (P < 0.01). Of the H. pylori-positive cancerous tissues, 50% (13/26) had MUC1 expression and 38.5% (10/26) had MUC6 expression. In comparison, of the H. pylori-negative cancerous tissues, 80% (16/20) had MUC1 expression (P < 0.05) and 80% (16/20) had MUC6 expression (P < 0.01).

CONCLUSIONS

The results indicate that H. pylori infection can alter the expression of some mucin genes in pericancerous mucosa and cancerous tissues of gastric carcinoma, then destroy the gastric mucosa barrier.

Differences in biological features of gastric dysplasia, indefinite dysplasia, reactive hyperplasia and discriminant analysis of these lesions

AIM: To investigate the differences in biological features of gastric dysplasia (Dys), indefinite dysplasia (IDys) and reactive hyperplasia (RH) by studying the biomarker alterations in cell proliferation, cell differentiation, cell cycle control and the expression of house-keeping genes, and further to search for markers which could be used in guiding the pathological diagnosis of three lesions.

METHODS: Expressions of MUC5AC, MUC6, adenomatous polyposis coli (APC), p53, Ki-67, proliferation cell nuclear antigen (PCNA) and EGFR were studied by immunohistochemistry with a standard Envision technique in formalin-fixed and paraffin-embedded specimens from 43 RH, 35 IDys, 35 Dys and 36 intestinal type gastric carcinomas (IGC). In addition, Bayes discriminant analysis was used to investigate the value of markers studied in differential diagnosis of RH, IDys, Dys and IGC.

RESULTS: The MUC5AC and MUC6 antigen expressions in RH, IDys, Dys and IGC decreased gradually (MUC5AC: 86.04%, 77.14%, 28.57%, 6.67%; MUC6: 65.15%, 54.29%, 20.00%, 25.00%, respectively). The expressions of the two markers had no significant difference between RH and IDys, but were all significantly higher than those of the other two lesions (MUC5AC: χ² = 27.607, 38.027 and 17.33, 26.092; MUC6: χ² = 16.54, 12.665 and 9.282, 6.737, P<0.01). There was no significant difference between RH and IDys, Dys and IGC in MUC6 expression. The APC gene expression in the four lesions had a similar decreasing tendency (RH 69.76%, IDys 68.57%, Dys 39.39%, IGC 22.86%), and it was significantly higher in the first two lesions than in the last two (χ² = 7.011, 16.995 and 14.737, 19.817, P<0.05). The p53 expression in RH, IDys, Dys and IGC was 6.98%, 20%, 57.14% and 50%, respectively. There was no significant difference between RH and IDys or Dys and IGC, but the p53 expression in RH and IDys was significantly lower than that in Dys and IGC (χ² = 7.011, 16.995 and 14.737, 19.817, P<0.01). The Ki-67 label index was significantly different among four lesions (RH: 0.298±8.92%, IDys: 0.358±9.25%, Dys: 0.498±9.03%, IGC: 0.620±10.8%, P<0.001). Positive immunostaining of PCNA was though observed in all specimens, significant differences were detected among four lesions (F = 95.318, P<0.01). In addition, we used Bayes discriminant analysis to investigate molecular pathological classification of the lesions, and obtained the best result with the combination of MUC5AC, Ki-67 and PCNA. The overall rate of correct classification was 67.4% (RH), 68.6% (IDys), 70.6% (Dys) and 84.8% (IGC), respectively.

CONCLUSION: Dys has neoplastic biological characteristics, while RH and IDys display hyperplastic characteristics. MUC5AC and proliferation-related biomarkers (Ki-67, PCNA) are more specific in distinguishing Dys from RH and IDys.

Histological changes in the gastric mucosa after Helicobacter pylori eradication

BACKGROUND AND AIM

Correa described a stepwise model of changes in the gastric mucosa after Helicobacter pylori infection, from the normal gastric epithelium to chronic gastritis, atrophy, intestinal metaplasia, dysplasia and adenocarcinoma. The aim of this study is to assess the reversibility of these mucosal changes after H. pylori eradication.

METHODS

The study sample consisted of 89 patients who underwent at least two gastric biopsies from 1990 to 2000, with a positive finding for H. pylori in the first and a negative finding in the second. Specimens were evaluated for acute and chronic inflammation, lymphoid aggregates, proliferation, mucosal atrophy, intestinal metaplasia, dysplasia, and MUC5AC and MUC6 expression using histochemical and immunohistochemical methods.

RESULTS

The average time between biopsies was 23.15 +/- 26.30 months. There was a significant decrease in acute and chronic inflammation scores, from 1.48 +/- 1.10 to 0.23 +/- 0.63 and from 2.67 +/- 0.68 to 1.44 +/- 1.04, respectively (P < 0.001), and in a number of lymphoid follicles, from 42.68% to 21.95% of cases (P < 0.008). The number of glands increased from 39.08 +/- 16.67/mm to 48.86 +/- 17.93/mm after eradication (P = 0.062). Intestinal metaplasia was found in 17.07% of the cases, with no change over time. Dysplasia appeared in one case 2 years after eradication. In 27 patients, the Ki67 labeling index decreased significantly after eradication, while MUC5AC and MUC6 expression increased.

CONCLUSION

Our findings, although not conclusive for arrest of the malignant potential, support the importance of H. pylori eradication in the prevention of gastric cancer.

Aberrant epithelial expression of trefoil family factor 2 and mucin 6 in Helicobacter pylori infected gastric antrum, incisura, and body and its association with antralisation

AIMS

To determine gastric expression of trefoil family factor 2 (TFF2) and MUC6 in Helicobacter pylori positive and negative subjects, and its association with antralisation at the gastric incisura.

METHODS

Gastric biopsies from the antrum, incisura, and body of 76 dyspeptic patients without ulcers were used for the determination of H. pylori infection, histological changes, and epithelial TFF2 and MUC6 expression.

RESULTS

In the foveola, the rates of TFF2 and MUC6 immunostaining were greater in H. pylori infected (n = 27) than in uninfected patients (n = 49) at the antrum (59.3% v 4.1% for TFF2 and 63.0% v 4.1% for MUC6; both p < 0.001) and incisura (44.4% v 2.0% for TFF2 and 48.1% v 0% for MUC6; both p < 0.001). In the deeper glands, the rates were also greater in H. pylori infected than in uninfected patients at the incisura (85.2% v 22.4% for both TFF2 and MUC6; p < 0.001). Antral-type mucosa was present at the incisura in 28 of the 76 patients. TFF2 and MUC6 expression in the foveola and deeper glands was significantly associated with antral-type mucosa, independent of H. pylori status.

CONCLUSIONS

Helicobacter pylori infection increases the expression of TFF2 and MUC6 in the gastric epithelium. Aberrant TFF2 and MUC6 expression is associated with antralisation of gastric incisura.