Persistent infection with Helicobacter pylori and the development of gastric cancer

Bacterial infection and microbiota in carcinogenesis and tumor development

Microbiota colonize exposed body tissues (e.g., gastrointestinal tract, skin, lungs, female genital tract, and urogenital tracts) and unexposed sites (e.g., breast). Persistent bacterial infection in the host lead to the development of multiple disease. They are implicated in the pathogenesis of various complex diseases, including diabetes, atherosclerosis, autoimmune diseases, Alzheimer's disease, and malignant diseases. Amounting studies have demonstrated the role of bacterial infection in carcinogenesis. The study of microbiota in tumorigenesis is primarily focused on lung cancer, colorectal cancer (CRC), breast cancer, gastric cancer, and gynecologic tumors, and so on. Infection of Helicobacter pylori in gastric cancer carcinogenesis is recognized as class I carcinogen by the World Health Organization (WHO) decades ago. The role of Fusobacterium nucleatum in the development of colorectal cancer is extensively investigated. Variable bacteria have been cultured from the tumor tissues. The identification of microbiota in multiple tumor tissues reveal that bacterial infection and microbiota are associated with tumor development. The microbiota affects multiple aspects of carcinogenesis and tumor development, including favoring epithelial cells proliferation, establishing inflammatory microenvironment, promoting metastasis, and causing resistance to therapy. On the other hand, microbiota can shape a tumor surveillance environment by enhancing cell activity, and sensitize the tumor cells to immune therapy. In the present review, the roles of microbiota in multiple malignancies are summarized, and unraveling the mechanisms of host-microbiota interactions can contribute to a better understanding of the interaction between microbiota and host cells, also the development of potential anti-tumor therapeutic strategies.

Role of TNF-α-Inducing Protein Secreted by Helicobacter pylori as a Tumor Promoter in Gastric Cancer and Emerging Preventive Strategies

The tumor necrosis factor-α (TNF-α)-inducing protein (tipα) gene family, comprising Helicobacter pylori membrane protein 1 (hp-mp1) and tipα, has been identified as a tumor promoter, contributing to H. pylori carcinogenicity. Tipα is a unique H. pylori protein with no similarity to other pathogenicity factors, CagA, VacA, and urease. American H. pylori strains cause human gastric cancer, whereas African strains cause gastritis. The presence of Tipα in American and Euro-Asian strains suggests its involvement in human gastric cancer development. Tipα secreted from H. pylori stimulates gastric cancer development by inducing TNF-α, an endogenous tumor promoter, through its interaction with nucleolin, a Tipα receptor. This review covers the following topics: tumor-promoting activity of the Tipα family members HP-MP1 and Tipα, the mechanism underlying this activity of Tipα via binding to the cell-surface receptor, nucleolin, the crystal structure of rdel-Tipα and N-terminal truncated rTipα, inhibition of Tipα-associated gastric carcinogenesis by tumor suppressor B-cell translocation gene 2 (BTG2/TIS21), and new strategies to prevent and treat gastric cancer. Thus, Tipα contributes to the carcinogenicity of H. pylori by a mechanism that differs from those of CagA and VacA.

Antiproliferative, Proapoptotic, Antioxidant and Antimicrobial Effects of Sinapis nigra L. and Sinapis alba L. Extracts

High Brassicaceae consumption reduces the risk of developing several cancer types, probably due to high levels of glucosinolates. Extracts from Sinapis nigra L. (S. nigra) and Sinapis alba L. (S. alba) have been obtained from leaves and seeds under different conditions using ethanol/water mixtures because their glucosinolates are well accepted by the food industry. The EtOH/H₂O 8:2 mixture gives better yields in glucosinolate amounts from ground seeds, mainly, sinalbin in S. alba and sinigrin in S. nigra. The highest antiproliferative activity in both non-tumor and tumor cell lines was induced by S. alba seeds extract. To evaluate whether the effect of Sinapis species (spp) was only due to glucosinolate content or whether it was influenced by the extracts’ complexity, cells were treated with extracts or glucosinolates, in the presence of myrosinase. Pure sinigrin did not modify cell proliferation, while pure sinalbin was less effective than the extract. The addition of myrosinase increased the antiproliferative effects of the S. nigra extract and sinigrin. Antiproliferative activity was correlated to Mitogen-Activated Protein Kinases modulation, which was cell and extract-dependent. Cell-cycle analysis evidenced a proapoptotic effect of S. alba on both tumor cell lines and of S. nigra only on HCT 116. Both extracts showed good antimicrobial activity in disc diffusion tests and on ready-to-eat fresh salad. These results underline the potential effects of Sinapis spp in chemoprevention and food preservation.

Relationship of the mucosal microbiota to gastrointestinal inflammation and small cell intestinal lymphoma in cats

Background

The gastrointestinal (GI) microbiota in healthy cats is altered in IBD. Little research has been performed to identify whether specific bacterial groups are associated with small cell GI lymphoma (LSA).

Hypothesis

Mucosal bacteria, including Enterobacteriaceae and Fusobacterium spp., are abundant in intestinal biopsies of cats with small cell GI LSA compared to cats with IBD.

Animals

Fourteen cats with IBD and 14 cats with small cell GI LSA.

Methods

Retrospective case control study. A search of the medical records was performed to identify cats diagnosed with IBD and with GI LSA. Bacterial groups identified by FISH in GI biopsies were compared between cohorts and correlated to CD11b⁺ and NF‐κB expression.

Results

Fusobacterium spp. (median; IQR bacteria/region) were higher in cats with small cell GI LSA in ileal (527; 455.5 – 661.5; P = .046) and colonic (404.5; 328.8 – 455.5; P = .016) adherent mucus, and combined colonic compartments (free mucus, adherent mucus, attaching to epithelium) (8; 0 – 336; P = .017) compared to cats with IBD (ileum: 67; 31.5 – 259; colon: 142.5; 82.3 – 434.5; combined: 3; 0 – 34). Bacteroides spp. were higher in ileal adherent mucus (P = .036) and 3 combined ileal compartments (P = .034) of cats with small cell GI LSA. There were significant correlations between Fusobacterium spp. totals and CD11b⁺ cell (P = .009; rs .476) and NF‐κB expression (P = .004; rs .523).

Conclusions

The bacterial alterations appreciated might be influential in development of small cell GI LSA, and should drive further studies to elucidate the effects of microbial‐mediated inflammation on GI cancer progression.

Inhibition of lipopolysaccharide (LPS)-induced neuroinflammatory response by polysaccharide fractions of Khaya grandifoliola (C.D.C.) stem bark, Cryptolepis sanguinolenta (Lindl.) Schltr and Cymbopogon citratus Stapf leaves in raw 264.7 macrophages and U87 glioblastoma cells

Background

Khaya grandifoliola (C.D.C.) stem bark, Cymbopogon citratus (Stapf) and Cryptolepis sanguinolenta (Lindl.) Schltr leaves are used in Cameroonian traditional medicine for the treatment of inflammatory diseases. Several studies have been performed on the biological activities of secondary metabolites extracted from these plants. However, to the best of our knowledge, the anti-neuro inflammatory and protective roles of the polysaccharides of these three plants have not yet been elucidated. This study aimed at investigating potential use of K. grandifoliola, C. sanguinolenta and C. citratus polysaccharides in the prevention of chronic inflammation.

Methods

Firstly, the composition of polysaccharide fractions isolated from K. grandifoliola stem bark (KGF), C. sanguinolenta (CSF) and C. citratus (CCF) leaves was assessed. Secondly, the cytotoxicity was evaluated on Raw 264.7 macrophages and U87-MG glioblastoma cell lines by the MTT assay. This was followed by the in vitro evaluation of the ability of KGF, CSF and CCF to inhibit lipopolysaccharides (LPS) induced overproduction of various pro-inflammatory mediators (NO, ROS and IL1β, TNFα, IL6, NF-kB cytokines). This was done in Raw 264.7 and U87-MG cells. Finally, the in vitro protective effect of KGF, CSF and CCF against LPS-induced toxicity in the U87-MG cells was evaluated.

Results

CCF was shown to mostly contain sugar and no polyphenol while KGP and CSP contained very few amounts of these metabolites (≤ 2%). The three polysaccharide fractions were non-toxic up to 100 μg.mL^− 1. All the polysaccharides at 10 μg/mL inhibited NO production, but only KGF and CCF at 12.5 μg/mL down-regulated LPS-induced ROS overproduction. Finally, 100 μg/mL LPS reduced 50% of U87 cell viability, and pre-treatment with the three polysaccharides significantly increased the proliferation.

Conclusion

These results suggest that the polysaccharides of K. grandifoliola, C. citratus and C. sanguinolenta could be beneficial in preventing/treating neurodegenerative diseases in which neuroinflammation is part of the pathophysiology.

Functional genetic variants of TNFSF15 and their association with gastric adenocarcinoma: a case-control study

The purpose of this study was to identify functional genetic variants in the promoter of tumor necrosis factor superfamily member 15 (TNFSF15) and evaluate their effects on the risk of developing gastric adenocarcinoma. Forty DNA samples from healthy volunteers were sequenced to identify single nucleotide polymorphisms (SNPs) in the TNFSF15 promoter. Two TNFSF15 SNPs (−358T>C and −638A>G) were identified by direct sequencing. Next, genotypes and haplotypes of 470 gastric adenocarcinoma patients and 470 cancer-free controls were analyzed. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated by logistic regression. Serologic tests for Helicobacter pylori infection were measured by enzyme-linked immuno-sorbent assay (ELISA). Subjects carrying the TNFSF15 −358CC genotype were at an elevated risk for developing gastric adenocarcinoma, compared with those with the −358TT genotype (OR 1.42, 95% CI, 1.10 to 2.03). H. pylori infection was a risk factor for developing gastric adenocarcinoma (OR 2.31, 95% CI, 1.76 to 3.04). In the H. pylori infected group, subjects with TNFSF15 −358CC genotype were at higher risks for gastric adenocarcinoma compared with those carrying −358TT genotype (OR: 2.01, 95%CI: 1.65 to 4.25), indicating that H. pylori infection further influenced gastric adenocarcinoma susceptibility. The −358 T>C polymorphism eliminates a nuclear factor Y (NF-Y) binding site and the −358C containing haplotypes showed significantly decreased luciferase expression compared with −358T containing haplotypes. Collectively these findings indicate that functional genetic variants in TNFSF15 may play a role in increasing susceptibility to gastric adenocarcinoma.

Epstein-Barr virus infection is common in inflamed gastrointestinal mucosa

BACKGROUND AND AIMS

Epstein-Barr virus (EBV) is present in the malignant epithelial cells of 10% of all gastric adenocarcinomas; however, localization of the virus in normal gastrointestinal mucosa is largely unexplored. In the present study, we measured EBV DNA and localized viral gene products in gastritis specimens (n = 89), normal gastric and colonic mucosa (n = 14), Crohn's disease (n = 9), and ulcerative colitis (n = 11) tissues.

METHODS

A battery of sensitive and specific quantitative polymerase chain reactions targeted six disparate regions of the EBV genome: BamH1 W, EBNA1, LMP1, LMP2, BZLF1, and EBER1. EBV infection was localized by EBV-encoded RNA (EBER) in situ hybridization and by immunohistochemical stains for viral latent proteins LMP1 and LMP2 and for viral lytic proteins BMRF1 and BZLF1. B lymphocytes were identified using CD20 immunostains.

RESULTS

EBV DNA was essentially undetectable in normal gastric mucosa but was present in 46% of gastritis lesions, 44% of normal colonic mucosa, 55% of Crohn's disease, and 64% of ulcerative colitis samples. Levels of EBV DNA exceeded what would be expected based on the numbers of B lymphocytes in inflamed tissues, suggesting that EBV is preferentially localized to inflammatory gastrointestinal lesions. Histochemical staining revealed EBER expression in lymphoid cells of some PCR-positive lesions. The viral lytic viral proteins, BMRF1 and BZLF1, were expressed in lymphoid cells of two ulcerative colitis tissues, both of which had relatively high viral loads by quantitative PCR.

CONCLUSION

EBV-infected lymphocytes are frequently present in inflamed gastric and colonic mucosa. Active viral replication in some lesions raises the possibility of virus-related perpetuation of gastrointestinal inflammation.

Natural isothiocyanates: genotoxic potential versus chemoprevention

Isothiocyanates, occurring in many dietary cruciferous vegetables, show interesting chemopreventive activities against several chronic-degenerative diseases, including cancer, cardiovascular diseases, neurodegeneration, diabetes. The electrophilic carbon residue in the isothiocyanate moiety reacts with biological nucleophiles and modification of proteins is recognized as a key mechanism underlying the biological activity of isothiocyanates. The nuclear factor-erythroid-2-related factor 2 system, which orchestrates the expression of a wide array of antioxidant genes, plays a role in the protective effect of isothiocyanates against almost all the pathological conditions reported above. Recent emerging findings suggest a further common mechanism. Chronic inflammation plays a central role in many human diseases and isothiocyanates inhibit the activity of many inflammation components, suppress cyclooxygenase 2, and irreversibly inactivate the macrophage migration inhibitory factor. Due to their electrophilic reactivity, some isothiocyanates are able to form adducts with DNA and induce gene mutations and chromosomal aberrations. DNA damage has been demonstrated to be involved in the pathogenesis of various chronic-degenerative diseases of epidemiological relevance. Thus, the genotoxicity of the isothiocyanates should be carefully considered. In addition, the dose-response relationship for genotoxic compounds does not suggest evidence of a threshold. Thus, chemicals that are genotoxic pose a greater potential risk to humans than non-genotoxic compounds. Dietary consumption levels of isothiocyanates appear to be several orders of magnitude lower than the doses used in the genotoxicity studies and thus it is highly unlikely that such toxicities would occur in humans. However, the beneficial properties of isothiocyanates stimulated an increase of dietary supplements and functional foods with highly enriched isothiocyanate concentrations on the market. Whether such concentrations may exert a potential health risk cannot be excluded with certainty and an accurate evaluation of the toxicological profile of isothiocyanates should be prompted before any major increase in their consumption be recommended or their clinical use suggested.

Inhibition of Lipopolysaccharide (LPS)-induced inflammatory responses by Sargassum hemiphyllum sulfated polysaccharide extract in RAW 264.7 macrophage cells

Sargassum hemiphyllum , a kind of brown seaweed generally found along coastlines in East Asia, has long served as a traditional Chinese medicine. S. hemiphyllum has shown an anti-inflammatory effect; however, its mechanism has not been elucidated clearly. This study explored S. hemiphyllum for its biomedical effects. S. hemiphyllum sulfated polysaccharide extract (SHSP) was first prepared; the mouse macrophage cell line (RAW 264.7) activated by lipopolysaccharide (LPS) was used as a model system. The secretion profiles of pro-inflammatory cytokines, including IL-1β, IL-6, TNF-α, and NO, were found significantly to be reduced in 1-5 mg/mL dose ranges of SHSP treatments. RT-PCR analysis suggested SHSP inhibits the LPS-induced mRNA expressions of IL-β, iNOS, and COX-2 in a dose-dependent manner. At protein levels, Western blot analysis demonstrated a similar result for NF-κB (p65) in cytosol/nuclear. Taken together, the anti-inflammatory properties of SHSP may be attributed to the down-regulation of NF-κB in nucleus.

Oral lichen planus is a unique disease model for studying chronic inflammation and oral cancer

Oral lichen planus (OLP) is a chronic inflammatory disease, which has been defined by the World Health Organization as a potential precancerous condition, representing a generalized state associated with a significantly increased risk of oral cancer. We would like to put forward a hypothesis that inflammatory mediators such as cytokines and chemokines released from infiltrating T lymphocytes induce fundamental changes of proteins in oral epithelial cells, leading to the progression of OLP to oral squamous cell carcinoma (OSCC). These altered proteins can act as the key risk factors associated with the local microenvironment and development of OSCC. Identification of these proteins would add to our understanding of the connection between chronic inflammation and OSCC.

Helicobacter pylori infection induces oxidative DNA damage in human gastric epithelial cell line GES-1 and human gastric cancer cell line SGC-7901

AIM: To investigate whether Helicobacter pylori (H. pylori) infection can induce oxidative DNA damage in human gastric epithelial cell line GES-1 and human gastric cancer cell line SGC-7901.

METHODS: H. pylori was co-cultured with GES-1 and SGC-7901 cells, respectively. The morphological changes of GES-1 and SGC-7901 cells between before and after co-culture were observed. The 8-OHdG expression in the two types of cells was detected by laser scanning confocal microscopy.

RESULTS: H. pylori infection induced oxidative DNA damage in both GES-1 and SGC-7901 cells. The expression levels of 8-OHdG in GES-1 and SGC-7901 cells co-cultured with H. pylori were significantly higher than those in control cells (64.9396 ± 17.8142 vs 32.3010 ± 7.3620 and 102.8344 ± 30.2632 vs 77.1336 ± 32.3223, respectively; both P = 0.000). The extent of 8-OHdG upregulation in GES-1 cells co-cultured with H. pylori was significantly higher than that in SGC-7901 cells co-cultured with H. pylori.

CONCLUSION: H. pylori infection induces oxidative DNA damage in both GES-1 and SGC-7901 cells. This result supports the hypothesis that H. pylori induced-oxidative DNA damage plays a pivotal role in the development of gastric carcinoma in patients with chronic gastritis. GES-1 cell line is superior to SGC-7901 cell line in the study of oxidative damage induced by H. pylori.

Structural basis for the Helicobacter pylori-carcinogenic TNF-alpha-inducing protein

Stomach cancer is strongly associated with infection by Helicobacter pylori. In 2005, we identified a new H. pylori gene encoding a TNF-alpha inducing protein (Tipalpha) that acts as a carcinogenic factor. Tipalpha is secreted from H. pylori as a homodimer whose subunits are linked by disulfide bonds. We also characterized a Tipalpha deletion mutant (del-Tipalpha) that lacks the N-terminal six amino acid residues (LQACTC), including two cysteines (C5 and C7) that form disulfide bonds, but nonetheless shows a weak ability to induce TNF-alpha expression. Here we report that del-Tipalpha has a novel elongated structure containing a 40-A-long alpha helix, and forms a heart-shaped homodimer via non-covalent bonds. Moreover, their circular dichroism spectra strongly suggest that the structures of the del-Tipalpha and Tipalpha homodimers are very similar. del-Tipalpha's unique mode of dimer formation provides important insight into protein-protein interactions and into the mechanism underlying the carcinogenicity of H. pylori infection.

A role for the substance P/NK-1 receptor complex in cell proliferation and apoptosis in oral lichen planus

OBJECTIVES

To determine whether substance P (SP) and NK-1 receptor (NK-1R) are expressed in oral lichen planus (OLP) and are related to cell proliferation and apoptosis in this disease.

MATERIAL AND METHODS

Tissue samples from 50 OLP patients and 26 healthy controls were studied. Immunohistochemistry was performed with anti-SP, anti-NK-1R, anti-ki-67 and anti-caspase-3 monoclonal antibodies and the clinical and pathological data of the OLP patients were evaluated.

RESULTS

With the exception of NK-1R expression in epithelial cell membrane and cytoplasm, all markers were more frequently present in OLP patients than in controls (P < 0.05). Higher cytoplasmatic expression of NK-1R was associated with higher epithelial expression of caspase-3 (P < 0.05). Higher epithelial expression of NK-1R and SP was associated with higher suprabasal and basal epithelial expression of ki-67 (P < 0.05 and P < 0.005, respectively).

CONCLUSIONS

Actions of the SP/NK-1R complex may contribute to the immune disorder underlying OLP and trigger stimuli to induce cell proliferation. These results indicate that this complex might play a role in the malignant transformation of OLP.

Helicobacter pylori-infection-associated CpG island hypermethylation in the stomach and its possible association with polycomb repressive marks

Helicobacter pylori infection can induce CpG island (CGI) hypermethylation in gastric mucosa. Recently, genes occupied by Polycomb proteins in embryonic stem cells were shown to be vulnerable to aberrant DNA hypermethylation in cancers. To explore the relationship between H. pylori infection and DNA methylation changes in neoplastic and non-neoplastic stomach, we analyzed 25 CGIs and repetitive DNA elements from 82 chronic gastritis and 69 gastric carcinomas. Twenty-three CGIs showed significantly higher methylation levels in H. pylori-negative gastric carcinoma (n = 28) than in H. pylori-negative chronic gastritis (n = 39; P < 0.05), indicating cancer-associated methylation. Eight CGIs exhibited significantly higher methylation levels in H. pylori-positive chronic gastritis (n = 43) than in H. pylori-negative chronic gastritis (n = 39; P < 0.05). Six CGIs showed both cancer-associated and H. pylori-associated hypermethylation. Six (75%) of the eight H. pylori-associated hypermethylated genes contained at least one of three repressive marks (Suzl2 occupancy, Eed occupancy, histone H3 K27 trimethylation), whereas 31% of the remaining cancer-associated hypermethylated genes had at least one mark. The findings suggest that H. pylori infection strongly induces CGI hypermethylation in gastric epithelial cells and that susceptibility to H. pylori-induced DNA hypermethylation may be determined by Polycomb repressive marks in stem or progenitor cells.

Oral lichen planus: controversies surrounding malignant transformation

Studies of the malignant potential of oral lichen planus (OLP) have been hampered by inconsistencies in the diagnostic criteria used for OLP, the criteria adopted to identify a true case of malignant transformation in OLP, the risk factors for malignant transformation and the optimum management of patients to ensure the early diagnosis of transformation. Consensus remains elusive, and leading workers in this field have recently published conflicting reports on the malignant potential of OLP and on the important question of the advisability of excluding patients with epithelial dysplasia or a tobacco habit from studies on this issue. The present review outlines these debates and proposes a possible a molecular basis for the malignant transformation in this disease.

Nitrative and oxidative DNA damage in cervical intraepithelial neoplasia associated with human papilloma virus infection

Recently, it was proposed that inflammation plays an integral role in the development of human papilloma virus (HPV)-induced cervical cancer. The present study sought to examine if 8-nitroguanine, a mutagenic nitrative DNA lesion formed during inflammation, contributes to cervical carcinogenesis. We obtained biopsy specimens from 30 patients with cervical intraepithelial neoplasia (CIN)1 (n = 9), CIN2 (n = 10), CIN3 (n = 6) and condyloma acuminatum (n = 5). We used immunohistochemistry to detect the formation of 8-nitroguanine and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), an oxidative DNA lesion, and compared it with the expression of the cyclin-dependent kinase inhibitor p16, which is considered to be a biomarker for cervical neoplasia. Double immunofluorescence labeling revealed that 8-nitroguanine and 8-oxodG were colocalized in cervical epithelial cells. Samples from CIN2-3 patients, most of whom were infected with high-risk HPV subtypes, exhibited significantly more intense staining for 8-nitroguanine than those with condyloma acuminatum. 8-Nitroguanine and 8-oxodG immunoreactivities correlated significantly with the CIN grade. We observed the expression of inducible nitric oxide synthase in epithelial and inflammatory cells from CIN lesions. Proliferating cell nuclear antigen was expressed specifically in dysplastic epithelial cells, but not in those of condyloma acuminatum. There were no statistically significant differences in p16 expression between CIN and condyloma acuminatum samples. These results suggest that high-risk HPV types promote inducible nitric oxide synthase-dependent DNA damage, which leads to dysplastic changes and carcinogenesis; in contrast, p16 appears to be merely a marker of HPV infection. Thus, 8-nitroguanine is a more suitable and promising biomarker for evaluating the risk of inflammation-mediated cervical carcinogenesis than p16.

Plastic cells and populations: DNA substrate characteristics in Helicobacter pylori transformation define a flexible but conservative system for genomic variation

Helicobacter pylori, bacteria that colonize the human gastric mucosa, are naturally competent for transformation by exogenous DNA, and show a panmictic population structure. To understand the mechanisms involved in its horizontal gene transfer, we sought to define the interval required from exposure to substrate DNA until DNA uptake and expression of a selectable phenotype, as well as the relationship of transforming fragment length, concentration, homology, symmetry, and strandedness, to the transformation frequency. We provide evidence that natural transformation in H. pylori differs in efficiency among wild-type strains but is saturable and varies with substrate DNA length, symmetry, strandedness, and species origin. We show that H. pylori cells can be transformed within one minute of contact with DNA, by DNA fragments as small as 50 bp, and as few as 5 bp on one flank of a selectable single nucleotide mutation is sufficient substrate for recombination of a transforming fragment, and that double-stranded DNA is the preferred (1000-fold >single-stranded) substrate. The high efficiency of double-stranded DNA as transformation substrate, in conjunction with strain-specific restriction endonucleases suggests a model of short-fragment recombination favoring closest relatives, consistent with the observed H. pylori population biology.

Gastric epithelial cell proliferation and cagA status in Helicobacter pylori gastritis at different gastric sites

OBJECTIVE

Helicobacter pylori infection causes hyperproliferation which is believed to predispose to the development of gastric carcinoma. The aim of this study was to analyze epithelial cell proliferation topographically in H. pylori gastritis in relationship to cagA status.

MATERIAL AND METHODS

The proliferative index (PI: Ki-67-labeled nuclei/total number of foveolar nuclei) was determined in gastric mucosa biopsies taken at the antrum (lesser and greater curvatures), incisura, and corpus (greater curvature) from 78 patients with H. pylori gastritis and 20 H. pylori-negative patients. H. pylori and cagA status were determined by polymerase chain reaction (PCR) and serology.

RESULTS

PIs were significantly higher in H. pylori- and cagA-positive patients, in comparison with H. pylori- and cagA-negative patients, at all sites (p<or=0.002 and p<or=0.009) and in the antrum in comparison to the corpus, in both H. pylori-negative (p=0.04) and positive patients (p<10(-3)). At the antral lesser curvature, PIs were higher than in all the other sites, both in H. pylori- (p<or=0.002) and cagA-positive groups (p<or=0.02). The PI correlated directly and significantly with inflammation in infected patients (r=0.45, p<10(-3)) and in cagA-positive patients (r=0.41, p=0.005). The PI was significantly higher in the antrum of infected patients with atrophy (p=0.03) and intestinal metaplasia (p=0.05) than in those without atrophy and intestinal metaplasia, respectively.

CONCLUSIONS

We demonstrated that H. pylori infection and cagA-positive strains promote epithelial proliferation that was correlated with host inflammatory reaction and mostly at the antral lesser curvature, which is recognized as the area where most carcinomas arise.

Cruciferous vegetables and human cancer risk: epidemiologic evidence and mechanistic basis

Cruciferous vegetables are a rich source of glucosinolates and their hydrolysis products, including indoles and isothiocyanates, and high intake of cruciferous vegetables has been associated with lower risk of lung and colorectal cancer in some epidemiological studies. Glucosinolate hydrolysis products alter the metabolism or activity of sex hormones in ways that could inhibit the development of hormone-sensitive cancers, but evidence of an inverse association between cruciferous vegetable intake and breast or prostate cancer in humans is limited and inconsistent. Organizations such as the National Cancer Institute recommend the consumption of five to nine servings of fruits and vegetables daily, but separate recommendations for cruciferous vegetables have not been established. Isothiocyanates and indoles derived from the hydrolysis of glucosinolates, such as sulforaphane and indole-3-carbinol (I3C), have been implicated in a variety of anticarcinogenic mechanisms, but deleterious effects also have been reported in some experimental protocols, including tumor promotion over prolonged periods of exposure. Epidemiological studies indicate that human exposure to isothiocyanates and indoles through cruciferous vegetable consumption may decrease cancer risk, but the protective effects may be influenced by individual genetic variation (polymorphisms) in the metabolism and elimination of isothiocyanates from the body. Cooking procedures also affect the bioavailability and intake of glucosinolates and their derivatives. Supplementation with I3C or the related dimer 3,3'-diindolylmethane (DIM) alters urinary estrogen metabolite profiles in women, but the effects of I3C and DIM on breast cancer risk are not known. Small preliminary trials in humans suggest that I3C supplementation may be beneficial in treating conditions related to human papilloma virus infection, such as cervical intraepithelial neoplasia and recurrent respiratory papillomatosis, but larger randomized controlled trials are needed.

A paradigm for direct stress-induced mutation in prokaryotes

Environmental stresses may lead to selection for hypermutator bacterial cells, which have an increased chance of generating beneficial variants. With stress removal, cost of mutation exceeds the fitness advantage, selecting against hypermutators. Hypermutators arise through several mechanisms, including inactivation of mismatch repair genes (MMR) or induction of error-prone polymerases. Helicobacter pylori may provide an alternative mechanism of stress-induced mutagenesis, since it lacks the MMR genes and error-prone polymerases found in other bacterial species, and possesses an endogenously high mutation frequency. In this study, we expose H. pylori strains to reactive oxygen species and reactive nitrogen species, stressors found in their natural environment. These exposures directly resulted in elevated rates of spontaneous point mutation, deletion between direct repeats, and intergenomic recombination. We demonstrate that these effects are transient and do not involve selection for hypermutator strains. That H. pylori possesses direct repeats in regions where potential gene rearrangements can occur suggests a mechanism for targeted mutation in response to stress that avoids the deleterious fitness costs of fixed hypermutation. These studies provide a new paradigm for adaptation under increased selective pressures that may be present in other prokaryotes.

Citrus Auraptene Reduces Helicobacter pylori Colonization of Glandular Stomach Lesions in Mongolian Gerbils

We examined the efficacy of auraptene (AUR), an antioxidant agent of a citrus coumarin derivative, for suppressing gastric inflammation introduced by Helicobacter pylori (Hp) infection in Mongolian gerbils (MGs). Hp-infected MGs were placed on diets containing 100 or 500 ppm AUR for 7 weeks. Real-time PCR was used to estimate the Hp population in glandular stomach lesions, and a histological assessment of inflammation was performed. At a dose of 500 ppm, AUR reduced the Hp population to 21.9+/-12.0% of the control group (p<0.05). However, no apparent differences were seen in hematoxylin and eosin sections between AUR-administered and control groups. We conclude that dietary supplementation with 500 ppm of AUR suppresses Hp colonization, but does not reduce gastric inflammation.

Expression of NF-kappaB in Helicobacter pylori infection

Helicobacter pylori colonizes the gastric mucosa in humans and causes chronic gastritis. NF-kappaB has a key role as a mediator in mucosal inflammation. In this study, we examined the expression of NF-kappaB in the antral epithelial cells of H. pylori-infected and H. pylori-uninfected biopsies and examined these processes in relationship with grade and activity of gastritis, density of H. pylori, presence of the intestinal metaplasia, and atrophy. Fifty biopsies (35 H. pylori-positive patients and 15 H. pylori-negative controls) were studied. NF-kappaB immunohistochemical stain was performed. NF-kappaB activity in H. pylori-infected biopsies were markedly enhanced compared with uninflamed biopsies (P = 0.001). We also found positive correlation NF-kappaB expression with severity of gastritis (according to Sydney score) (P = 0.001), activity of gastritis (P = 0.046) and H. pylori load (P < 0.001), and atrophy (P = 0.004). We did not find a significant relationship between NF-kappaB and the presence of intestinal metaplasia (P = 0.355). These findings suggested that expression of NF-kappaB has an important role in H. pylori gastritis.

Bacterial populations as perfect gases: genomic integrity and diversification tensions in Helicobacter pylori

Microorganisms that persist in single hosts face particular challenges. Helicobacter pylori, an obligate bacterial parasite of the human stomach, has evolved a lifestyle that features interstrain competition and intraspecies cooperation, both of which involve horizontal gene transfer. Microbial species must maintain genomic integrity, yet H. pylori has evolved a complex nonlinear system for diversification that exists in dynamic tension with the mechanisms for ensuring fidelity. Here, we review these tensions and propose that they create a dynamic pool of genetic variants that is sufficiently genetically diverse to allow H. pylori to occupy all of the potential niches in the stomach.

Apoptosis in Helicobacter pylori gastritis is related to cagA status

BACKGROUND

Helicobacter pylori infection increases gastric epithelial cell apoptosis; however, the influence of cagA status is still controversial. We aimed to investigate if cagA status is related to apoptosis in H. pylori gastritis at different anatomic sites of the gastric mucosa.

MATERIALS AND METHODS

We studied by immunohistochemistry (streptavidin-biotin method) pro-apoptotic (Bax and Bak) and antiapoptotic (Bcl-2 and Bcl-x) proteins expression, scored from 0 to 4, in gastric biopsies, at the antrum (lesser and greater curvatures), incisura, and corpus (greater curvature) from 50 patients with H. pylori gastritis (22 males, 28 females, median age 40 years) and eight non-infected patients (6 males, median age 39.6 years). H. pylori and cagA status were determined by polymerase chain reaction.

RESULTS

Apoptotic proteins were expressed in a granular pattern, in the cytoplasm of foveolar cells; Bax and Bak expression was higher than Bcl-2 and Bcl-x in most cases and was significantly higher in patients infected by cagA-positive strains than in those infected by cagA-negative strains (p = .001). Bak expression was higher at the lesser curvature (antrum and incisura) than in the other regions (p = .002) and was correlated with atrophy. Anti-apoptotic proteins were significantly more expressed at the antral lesser curvature than in the other regions of the stomach (Bcl-2: p = .02; Bcl-x: p < .001).

CONCLUSIONS

Infection with cagA-positive strains is significantly associated with overexpression of pro-apoptotic proteins in the gastric mucosa, mainly at the antral lesser curvature, which may have a role on atrophy development. Anti-apoptotic proteins were also overexpressed at the lesser curvature, which may occur to keep epithelial cell turnover or might be related to malignant transformation.

UvrD helicase suppresses recombination and DNA damage-induced deletions

UvrD, a highly conserved helicase involved in mismatch repair, nucleotide excision repair (NER), and recombinational repair, plays a critical role in maintaining genomic stability and facilitating DNA lesion repair in many prokaryotic species. In this report, we focus on the UvrD homolog in Helicobacter pylori, a genetically diverse organism that lacks many known DNA repair proteins, including those involved in mismatch repair and recombinational repair, and that is noted for high levels of inter- and intragenomic recombination and mutation. H. pylori contains numerous DNA repeats in its compact genome and inhabits an environment rich in DNA-damaging agents that can lead to increased rearrangements between such repeats. We find that H. pylori UvrD functions to repair DNA damage and limit homologous recombination and DNA damage-induced genomic rearrangements between DNA repeats. Our results suggest that UvrD and other NER pathway proteins play a prominent role in maintaining genome integrity, especially after DNA damage; thus, NER may be especially critical in organisms such as H. pylori that face high-level genotoxic stress in vivo.

Role of pantoprazole in the treatment of gastro-oesophageal reflux disease

The diagnosis and treatment of gastro-oesophageal reflux disease (GERD) presents many problems, despite the fact that significant advances have been made in recent years in the understanding of its pathogenesis and symptomatology. GERD affects many people and has a significant negative impact on patient quality of life. Heartburn is the most common symptom of GERD which occurs with and without oesophagitis. The predominant causative factor for symptoms is prolonged contact of oesophageal mucosa with refluxed acid and pepsin. Proton pump inhibitors (PPIs) are the most effective treatment for GERD: overall proportions of patients with healing and complete heartburn relief are markedly higher with PPIs than with alternative treatment strategies. Furthermore, the speed of healing and heartburn relief with PPIs is almost twice as rapid as with any other form of therapy. The present review focuses on the effectiveness and safety of the PPI, pantoprazole. The data show that the compound is highly effective in GERD patients with and without oesophagitis. Pantoprazole has an excellent safety record and shows only minor interaction with other drugs.

Carcinogenic role of tumor necrosis factor-alpha inducing protein of Helicobacter pylori in human stomach

Helicobacter pylori is the definitive carcinogen for stomach cancer and is known to induce proinflammatory cytokines, such as tumor necrosis factor-alpha (TNF-alpha) and interleukin-1(IL-1) in the stomach. Based on our findings that TNF-alpha is an endogenous tumor promoter, we identified the TNFalpha inducing protein (Tipalpha) gene family, and confirmed Tipalpha and HP-MP1 as new carcinogenic proteins of H. pylori.Tipalpha protein is unique to H. pylori, and this paper shows the strong tumor promoting activity of Tipalpha gene family, in cooperation with Ras protein and its mechanisms of action in relation to NF-kappaB activation, and discusses the carcinogenic role of Tipalpha in stomach cancer. Our recent finding showing that penicillin-binding proteins of other bacteria are weak homologues of Tipalpha is also discussed.

Gastric Cancer (Biomarkers) Knowledgebase (GCBKB): A Curated and Fully Integrated Knowledgebase of Putative Biomarkers Related to Gastric Cancer

The Gastric Cancer (Biomarkers) Knowledgebase (GCBKB) ( http://biomarkers.bii.a-star.edu.sg/background/gastricCancerBiomarkersKb.php ) is a curated and fully integrated knowledgebase that provides data relating to putative biomarkers that may be used in the diagnosis and prognosis of gastric cancer. It is freely available to all users. The data contained in the knowledgebase was derived from a large literature source and the putative biomarkers therein have been annotated with data from the public domain. The knowledgebase is maintained by a curation team who update the data from a defined source. As well as mining data from the literature, the knowledgebase will also be populated with unpublished experimental data from investigators working in the gastric cancer biomarker discovery field. Users can perform searches to identify potential markers defined by experiment type, tissue type and disease state. Search results may be saved, manipulated and retrieved at a later date. As far as the authors are aware this is the first open access database dedicated to the discovery and investigation of gastric cancer biomarkers.

Relevance of adjusted cut-off values in commercial serological immunoassays for Helicobacter pylori infection in children

We assessed the sensitivity and specificity of H. pylori IgG and IgA with a commercial immunoassay performed in Chile and a second non-commercial immunoassay performed in a reference laboratory in the United States, in serum of 80 children and adults referred for gastrointestinal endoscopies in a developing country. Overall, 56% of the patients were infected with H. pylori based on rapid urease test and staining techniques on gastric biopsies. When Receiver Operator Curves (ROC) were developed, the sensitivity and specificity were similar for IgG and IgA. Both immunoassays exhibited better specificity, positive and negative predictive value (NPV) in children than in adults when cut-off values were corrected according to the local population than when they were assessed using the cut-off values pre-defined in other populations. These results underline the need to establish more precise cut-off values corrected in the local populations where assessments of antibodies as diagnostic markers of H. pylori infection are planning.

Nitrative and oxidative DNA damage in oral lichen planus in relation to human oral carcinogenesis

Oral lichen planus (OLP) is a chronic inflammatory disease, which has been clinically associated with development to oral cancer. A double immunofluorescence labeling study found that 8-nitroguanine and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) accumulated in oral epithelium in OLP and oral squamous cell carcinoma (OSCC) biopsy specimens, whereas little or no immunoreactivity was observed in normal oral mucosa. Colocalization of 8-nitroguanine and inducible nitric oxide synthase (iNOS) was found in oral epithelium of OLP and OSCC. Immunoreactivity of 3-nitrotyrosine, which is formed by protein tyrosine nitration and is considered to be a biochemical marker for inflammation, was also observed in oral epithelial cells and colocalized with 8-nitroguanine. Accumulation of p53 was more strongly observed in oral epithelium in OSCC than OLP, whereas there was no p53 accumulation in normal oral mucosa. Our findings demonstrate that iNOS-dependent DNA damage in OLP may lead to p53 accumulation in not only OLP but also OSCC. We conclude that the formation of potentially mutagenic DNA lesions including 8-nitroguanine and 8-oxodG may contribute to the development of oral cancer from OLP.

Host-Environment Interactions: Their Impact on Progression from Gastric Inflammation to Carcinogenesis and on Development of New Approaches to Prevent and Treat Gastric Cancer

Revelation of the connection between Helicobacter pylori infection and gastric adenocarcinoma has prompted new investigations pertaining to its basic and clinical aspects. H. pylori-induced persistent and uncontrolled gastric inflammation nearly always precedes the development of cancer and is instrumental in initiating a multistep process leading to carcinogenesis. Despite initial optimism about the potential of combination anti-H. pylori therapy to ultimately eradicate gastric adenocarcinoma, recent investigations suggest its use should be targeted and tailored to a selected patient group considering the multifaceted role of H. pylori in disease and the disease heterogeneity of gastric adenocarcinoma. The clinical spectrum of H. pylori infection ranges from asymptomatic gastritis and peptic ulcer to gastric malignancies. The occurrence of one versus another is the result of differences in the magnitude of gastritis, and the current disease paradigm suggests gastric inflammation is common to all H. pylori-associated gastroduodenal diseases. Therefore, the host inflammatory responses to environmental triggers, rather than to bacteria or environmental factors per se, would dictate the variable outcomes of H. pylori infection. Putative factors that are expected to play an important role in stimulating inflammatory pathways and modulating the cross-talk between host and environment are age at the time of infection, environmental cofactors, H. pylori virulence, and host genetics. Elucidation of the intimate relationship between host-environment interaction and gastric inflammation, although currently a formidable task, is essential in the development of new prevention and treatment strategies. Such knowledge might provide clues that allow more accurate prediction of variable outcomes of gastric inflammation and appropriate adjustment of treatment strategies, and might open up novel areas for studying gastric carcinogenesis. The evolving new technologies, such as microarray, proteomic, and functional genomic analyses, promise to shed new light on the immense complexity of the presumed host-environment interactions and will reveal more useful markers for the diagnosis and prognosis of gastric adenocarcinoma.

New tumor necrosis factor-alpha-inducing protein released from Helicobacter pylori for gastric cancer progression

PURPOSE

To investigate the association between Helicobacter pylori infection and its inflammatory reaction in gastritis, gastric ulcer, and gastric cancer, a new tumor necrosis factor-alpha (TNF-alpha)-inducing protein of H. pylori was studied.

METHODS

The HP0596 gene of H. pylori was identified as the TNF-alpha-inducing protein (Tipalpha) gene from genome sequence of H. pylori strain 26695. Using recombinant Tipalpha (rTipalpha) and deleted Tipalpha (rdel-Tipalpha) proteins, the latter of which lacks six amino acids containing two cysteines in the N-terminal domain, we examined their activities in TNF-alpha gene expression and NF-kappaB activation in both Bhas 42 (v-H-ras transfected BALB/3T3) cells and mouse gastric epithelial cell line MGT-40, and in vitro transformation of Bhas 42 cells.

RESULTS

Tipalpha protein as a homodimer form (38 kDa) was found in both extracts and culture medium of various H. pylori strains. rTipalpha significantly induced TNF-alpha gene expression and NF-kappaB activation in both Bhas 42 cells and MGT-40, and induced in vitro transformation of Bhas 42 cells. However, rdel-Tipalpha did not. Treatment with MG-132, a proteasome inhibitor, inhibited translocation of NF-kappaB p65, and abrogated TNF-alpha induction induced by Tipalpha protein.

CONCLUSION

Tipalpha is a new carcinogenic factor released from H. pylori mediated through NF-kappaB activation.

New tumor necrosis factor-alpha-inducing protein released from Helicobacter pylori for gastric cancer progression

PURPOSE

To investigate the association between Helicobacter pylori infection and its inflammatory reaction in gastritis, gastric ulcer, and gastric cancer, a new tumor necrosis factor-alpha (TNF-alpha)-inducing protein of H. pylori was studied.

METHODS

The HP0596 gene of H. pylori was identified as the TNF-alpha-inducing protein (Tipalpha) gene from genome sequence of H. pylori strain 26695. Using recombinant Tipalpha (rTipalpha) and deleted Tipalpha (rdel-Tipalpha) proteins, the latter of which lacks six amino acids containing two cysteines in the N-terminal domain, we examined their activities in TNF-alpha gene expression and NF-kappaB activation in both Bhas 42 (v-H-ras transfected BALB/3T3) cells and mouse gastric epithelial cell line MGT-40, and in vitro transformation of Bhas 42 cells.

RESULTS

Tipalpha protein as a homodimer form (38 kDa) was found in both extracts and culture medium of various H. pylori strains. rTipalpha significantly induced TNF-alpha gene expression and NF-kappaB activation in both Bhas 42 cells and MGT-40, and induced in vitro transformation of Bhas 42 cells. However, rdel-Tipalpha did not. Treatment with MG-132, a proteasome inhibitor, inhibited translocation of NF-kappaB p65, and abrogated TNF-alpha induction induced by Tipalpha protein.

CONCLUSION

Tipalpha is a new carcinogenic factor released from H. pylori mediated through NF-kappaB activation.

Functions of NF-kappaB1 and NF-kappaB2 in immune cell biology

Two members of the NF-kappaB (nuclear factor kappaB)/Rel transcription factor family, NF-kappaB1 and NF-kappaB2, are produced as precursor proteins, NF-kappaB1 p105 and NF-kappaB2 p100 respectively. These are proteolytically processed by the proteasome to produce the mature transcription factors NF-kappaB1 p50 and NF-kappaB2 p52. p105 and p100 are known to function additionally as IkappaBs (inhibitors of NF-kappaB), which retain associated NF-kappaB subunits in the cytoplasm of unstimulated cells. The present review focuses on the latest advances in research on the function of NF-kappaB1 and NF-kappaB2 in immune cells. NF-kappaB2 p100 processing has recently been shown to be stimulated by a subset of NF-kappaB inducers, including lymphotoxin-beta, B-cell activating factor and CD40 ligand, via a novel signalling pathway. This promotes the nuclear translocation of p52-containing NF-kappaB dimers, which regulate peripheral lymphoid organogenesis and B-lymphocyte differentiation. Increased p100 processing also contributes to the malignant phenotype of certain T- and B-cell lymphomas. NF-kappaB1 has a distinct function from NF-kappaB2, and is important in controlling lymphocyte and macrophage function in immune and inflammatory responses. In contrast with p100, p105 is constitutively processed to p50. However, after stimulation with agonists, such as tumour necrosis factor-alpha and lipopolysaccharide, p105 is completely degraded by the proteasome. This releases associated p50, which translocates into the nucleus to modulate target gene expression. p105 degradation also liberates the p105-associated MAP kinase (mitogen-activated protein kinase) kinase kinase TPL-2 (tumour progression locus-2), which can then activate the ERK (extracellular-signal-regulated kinase)/MAP kinase cascade. Thus, in addition to its role in NF-kappaB activation, p105 functions as a regulator of MAP kinase signalling.

Accumulation of 8-nitroguanine in human gastric epithelium induced by Helicobacter pylori infection

Helicobacter pylori infection causes chronic inflammation, which can lead to gastric carcinoma. A double immunofluorescence labeling study demonstrated that the level of 8-nitroguanine and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) apparent in gastric gland epithelium was significantly higher in gastritis patients with H. pylori infection than in those without infection. A significant accumulation of proliferating cell nuclear antigen, a prognostic factor for gastric cancer, was observed in gastric gland epithelial cells in patients with H. pylori infection as compared to those without infection, and its accumulation was closely correlated with the formation of 8-nitroguanine and 8-oxodG. These results suggest that nitrosative and oxidative DNA damage in gastric epithelial cells and their proliferation by H. pylori infection may lead to gastric carcinoma. 8-Nitroguanine could be not only a promising biomarker for inflammation but also a useful indicator of the risk of gastric cancer development in response to chronic H. pylori infection.