Expression of NF-kappaB in Helicobacter pylori infection

An Overview of Selected Bacterial Infections in Cancer, Their Virulence Factors, and Some Aspects of Infection Management

In cancer development and its clinical course, bacteria can be involved in etiology and secondary infection. Regarding etiology, various epidemiological studies have revealed that Helicobacter pylori can directly impact gastric carcinogenesis. The Helicobacter pylori-associated virulence factor cytotoxin-associated gene A perhaps plays an important role through different mechanisms such as aberrant DNA methylation, activation of nuclear factor kappa B, and modulation of the Wnt/β-catenin signaling pathway. Many other bacteria, including Salmonella and Pseudomonas, can also affect Wnt/β-catenin signaling. Although Helicobacter pylori is involved in both gastric adenocarcinoma and mucosa-associated lymphoid tissue lymphoma, its role in the latter disease is more complicated. Among other bacterial species, Chlamydia is linked with a diverse range of diseases including cancers of different sites. The cellular organizations of Chlamydia are highly complex. Interestingly, Escherichia coli is believed to be associated with colon cancer development. Microorganisms such as Escherichia coli and Pseudomonas aeruginosa are frequently isolated from secondary infections in cancer patients. In these patients, the common sites of infection are the respiratory, gastrointestinal, and urinary tracts. There is an alarming rise in infections with multidrug-resistant bacteria and the scarcity of suitable antimicrobial agents adversely influences prognosis. Therefore, effective implementation of antimicrobial stewardship strategies is important in cancer patients.

Mechanism of action of NF-κB related cell signaling pathways in progression of gastritis to carcinoma

Gastric cancer (GC) is a major global public health problem. The evolvement pattern of "superficial gastritis-chronic atrophic gastritis-intestinal metaplasia-dysplasia-gastric carcinoma" is common in related gastric diseases. As a key factor involved in systemic stress response, inflammatory response, and apoptosis, the regulation of NF-κB related to inflammation and apoptosis is a necessary link between inflammation and cancer progression. NF-κB is activated in most solid tumors and lymphomas. In the critical mechanism of gastric cancer induced by gastritis with various etiologies, the upstream and downstream molecules in the NF-κB signaling pathway are changed, and the cells are exposed to the microenvironment of inflammatory response for a long time, which ultimately leads to the development of their carcinogenic potential. This article discusses the mechanism of NF-κB in the key risk factors for the progression of gastric disease.

Study of the correlation between the expression of nuclear factor kappa B and proliferation regulatory proteins and chronic superficial gastritis

Background/Aim. Cell proliferation and the regulation of protein expression play an important role in gastritis, but in chronic superficial gastritis (CSG), they are rarely reported. The aim of this study was to determine the relationship between the expression of nuclear factor kappa B (NF-?B) and regulatory proteins and the rat CSG. Methods. The CSG rat model was established artificially, by chemical agents and irregular diet. The expression of epidermal growth factor receptor (EGFR) and proliferating cell nuclear antigen (PCNA) in the gastric mucosa of CSG rats was measured by immunohistochemistry, while mRNA expression levels of NF-?B p65 were detected by in situ hybridization. Results. There was more obvious infiltration of inflammatory cells in the gastric mucosa of CSG rats than in that of control rats, and the inflammation score was significantly increased. The expression levels of PCNA, EGFR, and NF-?B p65 mRNA in the gastric mucosal cells of CSG model rats increased significantly. Correlation analysis showed that the inflammation score was positively correlated with the expression levels of NF-?B p65 mRNA and EGFR, while it presented no significant correlation with the expression level of PCNA. In addition, there was a significant positive correlation between NF-?B p65 mRNA and EGFR levels. Conclusion. High expression of NF-?B and EGFR plays an important role in the occurrence and progression of CSG, and it is significantly positively correlated with the degree of inflammation in the gastric mucosa. Therefore, changes in NF-?B and EGFR expression may be used as important indicators for the assessment of CSG; changes in their expression levels are helpful to assess the degree of gastric mucosal lesions and progression of CSG.

The protective effect of NF-κB signaling pathway inhibitor PDTC on mice with chronic atrophic gastritis

OBJECTIVE

To understand the protective effect of NF-κB signaling pathway inhibitor pyrrolidinedithiocarbamate (PDTC) on mice with chronic atrophic gastritis (CAG).

METHODS

Helicobacter pylori (H. pylori) infection combined with high-salt diet was used to construct the CAG mouse model, and 100 or 200 mg/kg/day PDTC was intragastrically treated for 8 weeks. Then, hematoxylin and eosin (HE) and Alcian blue-periodic acid-Schiff (AB-PAS) staining were used to observe the pathology of gastric mucosa, while immunohistochemistry, quantitative real-time polymerase chain reaction (qRT-PCR), enzyme-linked immuno sorbent assay (ELISA) and western blotting were determined to detect the expression of related molecules.

RESULTS

The nuclear content of NF-κB p65 in the gastric mucosa of the CAG mice was increased accompanying by the structural disorder of the gastric mucosal epithelium, inflammatory cell infiltration, intestinal metaplasia, and increased MUC2 expression, but the symptoms were alleviated after PDTC treatment. In addition, the expressions of TNF-α, IL-1β, IL-6 and COX2 in the gastric mucosa and serum of CAG mice were higher than those control mice, which were reduced in CAG mice treated with either 100 or 200 mg/kg PDTC. Furthermore, 100 mg/kg and 200 mg/kg PDTC treatments reduced the serum PGE₂ in CAG mice with the decreased PCNA and Ki-67 expression in gastric mucosa. The therapeutic effect of 200 mg/kg PDTC was significantly better than that of 100 mg/kg PDTC.

CONCLUSION

PDTC inhibited inflammation and the excessive proliferation of gastric mucosal epithelial cells, thereby exerting a potential therapeutic effect on CAG.

Lactobacillus fermentum UCO-979C beneficially modulates the innate immune response triggered by Helicobacter pylori infection in vitro

Helicobacter pylori infection is associated with important gastric pathologies. An aggressive proinflammatory immune response is generated in the gastric tissue infected with H. pylori, resulting in gastritis and a series of morphological changes that increase the susceptibility to cancer development. Probiotics could present an alternative solution to prevent or decrease H. pylori infection. Among them, the use of immunomodulatory lactic acid bacteria represents a promising option to reduce the severity of chronic inflammatory-mediated tissue damage and to improve protective immunity against H. pylori. We previously isolated Lactobacillus fermentum UCO-979C from human gastric tissue and demonstrated its capacity to reduce adhesion of H. pylori to human gastric epithelial cells (AGS cells). In this work, the ability of L. fermentum UCO-979C to modulate immune response in AGS cells and PMA phorbol 12-myristate 13-acetate (PMA)-differentiated THP-1 (human monocytic leukaemia) macrophages in response to H. pylori infection was evaluated. We demonstrated that the UCO-979C strain is able to differentially modulate the cytokine response of gastric epithelial cells and macrophages after H. pylori infection. Of note, L. fermentum UCO-979C was able to significantly reduce the production of inflammatory cytokines and chemokines in AGS and THP-1 cells as well as increase the levels of immunoregulatory cytokines, indicating a remarkable anti-inflammatory effect. These findings strongly support the probiotic potential of L. fermentum UCO-979C and provide evidence of its beneficial effects against the inflammatory damage induced by H. pylori infection. Although our findings should be proven in appropriate experiments in vivo, in both H. pylori infection animal models and human trials, the results of the present work provide a scientific rationale for the use of L. fermentum UCO-979C to prevent or reduce H. pylori-induced gastric inflammation in humans.

The Upregulation of TRAF1 Induced by Helicobacter pylori Plays an Antiapoptotic Effect on the Infected Cells

BACKGROUND

Tumor necrosis factor receptor-associated factor 1 (TRAF1) is a member of the TRAF family and is dysregulated in diseases, such as atheroma, lymphoma, and solid tumors, but the role of TRAF1 in gastric cancer remains unknown. This study was aimed to investigate the role of TRAF1 in Helicobacter pylori (H. pylori)-related cell apoptosis and gastric carcinogenesis.

MATERIALS AND METHODS

The mRNA and protein expression levels of TRAF1 were measured in a panel of gastric cancer cell lines and in H. pylori -infected mice by quantitative real-time PCR (qPCR) and Western blotting. The transcription factor that mainly affects transcription of TRAF1 during H. pylori infection was identified. The roles of H. pylori virulence factors that regulate TRAF1 expression were analyzed using isogenic cagA-, vacA-, and cagE-null mutants. The effects of TRAF1 on gastric cell viability and apoptosis during H. pylori infection were detected using the standard MTS (cell viability) assay and flow cytometry, respectively.

RESULTS

H. pylori infection induced TRAF1 overexpression in both gastric epithelial cells and mice. The expression of TRAF1 in response to H. pylori infection was majorly regulated by the activation of NF-κB and was strongly related to H. pylori virulence factor CagA. The upregulation of TRAF1 inhibited cell apoptosis and increased the viability of infected cells.

CONCLUSIONS

H. pylori infection induces the overexpression of TRAF1 in gastric epithelial cells. The upregulation of TRAF1 plays an antiapoptotic role in H. pylori -infected gastric cells and may contribute to the gastric carcinogenesis.

Probiotics against neoplastic transformation of gastric mucosa: Effects on cell proliferation and polyamine metabolism

Gastric cancer is still the second leading cause of cancer death worldwide, accounting for about 10% of newly diagnosed neoplasms. In the last decades, an emerging role has been attributed to the relations between the intestinal microbiota and the onset of both gastrointestinal and non-gastrointestinal neoplasms. Thus, exogenous microbial administration of peculiar bacterial strains (probiotics) has been suggested as having a profound influence on multiple processes associated with a change in cancer risk. The internationally accepted definition of probiotics is live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. The possible effects on the gastrointestinal tract following probiotic administration have been investigated in vitro and in animal models, as well as in healthy volunteers and in patients suffering from different human gastrointestinal diseases. Although several evidences are available on the use of probiotics against the carcinogen Helicobacter pylori, little is still known about the potential cross-interactions among probiotics, the composition and quality of intestinal flora and the neoplastic transformation of gastric mucosa. In this connection, a significant role in cell proliferation is played by polyamines (putrescine, spermidine, and spermine). These small amines are required in both pre-neoplastic and neoplastic tissue to sustain the cell growth and the evidences here provided suggest that probiotics may act as antineoplastic agents in the stomach by affecting also the polyamine content and functions. This review will summarize data on the most widely recognized effects of probiotics against neoplastic transformation of gastric mucosa and in particular on their ability in modulating cell proliferation, paying attention to the polyamine metabolism.

NF-κB activation and severity of gastritis in Helicobacter pylori-infected children and adults

BACKGROUND

In contrast to adults, Helicobacter pylori gastritis in children is reported as milder and ulcer disease as uncommon, but unequivocal data are lacking.

OBJECTIVES

To compare the frequency of gastro-duodenal ulcers in children and adults as well as the proportion of Helicobacter pylori infection in these patients and to study the effect of chronological age on NF-κB activation and on severity of gastritis.

DESIGN

Patients referred in one pediatric and one adult facility for upper GI endoscopy were included. Gastric biopsies were obtained in consecutive Helicobacter pylori-infected patients and age-matched negative controls for immunohistochemistry and electrophoresis mobility shift assay. Three age groups were defined: younger than 8 years, 8-17 years, and adults.

RESULTS

Peptic ulcer disease was less frequent in children and less frequently associated with Helicobacter pylori infection. When comparing infected subjects to controls, densities of neutrophils and CD20 cells in the lamina propria increased in all age groups, CD3 cells increasing only in patients older than 8 years and CD8 cells only in adults. NF-κB-p65-positive cells were also increased only in infected adults as well as NF-κB-binding activity. A positive correlation was found between age and densities of neutrophils and CD3, but not of CD8 or CD20 cells.

CONCLUSION

Peptic ulcer disease was less frequent in children and less frequently caused by Helicobacter pylori infection. The different clinical outcome of the infection in children can be the consequence of the lower mucosal immune response.

Lactobacillus acidophilus ameliorates H. pylori-induced gastric inflammation by inactivating the Smad7 and NFκB pathways

Background

H. pylori infection may trigger Smad7 and NFκB expression in the stomach, whereas probiotics promote gastrointestinal health and improve intestinal inflammation caused by pathogens. This study examines if probiotics can improve H. pylori-induced gastric inflammation by inactivating the Smad7 and NFκB pathways.

Results

Challenge with H. pylori increased IL-8 and TNF-α expressions but not TGF-β1 in MKN45 cells. The RNA levels of Smad7 in AGS cells increased after H. pylori infection in a dose-dependent manner. A higher dose (MOI 100) of L. acidophilus pre-treatment attenuated the H. pylori-induced IL-8 expressions, but not TGF-β1. Such anti-inflammatory effect was mediated via increased cytoplasmic IκBα and depletion of nuclear NFκB. L. acidophilus also inhibited H. pylori-induced Smad7 transcription by inactivating the Jak1 and Stat1 pathways, which might activate the TGF-β1/Smad pathway. L. acidophilus pre-treatment ameliorated IFN-γ-induced Smad7 translation level and subsequently reduced nuclear NF-κB production, as detected by western blotting.

Conclusions

H. pylori infection induces Smad7, NFκB, IL-8, and TNF-α production in vitro. Higher doses of L. acidophilus pre-treatment reduce H. pylori-induced inflammation through the inactivation of the Smad7 and NFκB pathways.

Helicobacter pylori induces promoter methylation of E-cadherin via interleukin-1β activation of nitric oxide production in gastric cancer cells

BACKGROUND

Helicobacter pylori infection causes gastric mucosal inflammatory responses, resulting in up-regulation of interleukin-1β (IL-1β) and overproduction of mutagenic nitric oxide (NO). The authors previously demonstrated that IL-1β plays an important role in H. pylori-induced E-cadherin (E-cad) methylation. Here, they extend the study to investigate the downstream effect of IL-1β on H. pylori-induced gastric inflammation and aberrant DNA methylation.

METHODS

Human gastric cancer cell lines (MKN7, MKN74, and TMK-1) with and without pretreatment of IL-1 receptor antagonist (IL-1ra) were treated with IL-1β or infected with H. pylori. Promoter methylation status of E-cad was examined by methylation-specific polymerase chain reaction (PCR). Expression of E-cad, inducible nitric oxide synthase (iNOS), and nuclear factor κB (NFκB) was assessed by quantitative reverse transcriptase PCR, Western blotting, or immunofluorescence. NO production and total DNA methyltransferase (DNMT) activity were assayed fluorometrically.

RESULTS

Both IL-1β treatment and H. pylori infection-induced E-cad methylation led to a decrease in E-cad expression at both mRNA and protein levels. Total DNMT enzymatic activity was significantly elevated in treated cells, accounting for the observed E-cad methylation induction. Increased expression of NFκB was accompanied by up-regulation of iNOS and production of NO in treated cells. Reversal of all these phenomena in cells pretreated with IL-1ra suggested H. pylori-induced E-cad methylation via IL-1β stimulation of the NFκB transcriptional system, leading to activation of DNMT activity by NO production.

CONCLUSIONS

These findings reveal a previously unknown effect of IL-1β and NO on H. pylori-induced aberrant DNA methylation. This possible pathway indicates the role of NO in epigenetic modification that links inflammation to carcinogenesis.

Down-regulation of Bcl-2 is mediated by NF-κB activation in Helicobacter pylori-induced apoptosis of gastric epithelial cells

OBJECTIVE

Bcl-2 family is involved in the regulation of apoptosis. NF-κB activation is associated with either the expression of Bcl-2 or down-regulation of Bcl-2 depending on cell types and stimuli. Previously, we showed NF-κB activation, decrease in the level of Bcl-2, and apoptosis in Helicobacter pylori (H. pylori)-infected gastric epithelial cells. The present study aims to investigate the relation of Bcl-2 expression and NF-κB activation in H. pylori-induced apoptotic cell death of AGS (gastric adenocarcinoma) cells.

MATERIAL AND METHODS

AGS cells were transfected with mutant IκBα to suppress NF-κB activation or Bcl-2 gene to induce overexpression of Bcl-2. mRNA expression of Bcl-2, p53 and Bax, DNA fragmentation, cell viability, and the numbers of apoptotic cells were determined.

RESULTS

H. pylori induced decrease in Bcl-2, but increase in p53 and Bax at the levels of mRNA and protein in AGS cells. H. pylori-induced increment of apoptotic cells and decrease in Bcl-2 level were inhibited in the cells transfected with mutant IκBα gene as compared with the cells transfected with control vector. H. pylori-induced apoptosis determined by apoptotic cells, DNA fragmentation, and cell viability was inhibited in the cells transfected with Bcl-2 gene.

CONCLUSION

Down-regulation of Bcl-2 is mediated by NF-κB activation, which may be the underlying mechanism of apoptosis in H. pylori-infected gastric epithelial cells.

[Thoughts on pathogenesis of Helicobacter pylori related gastrosis with splenogastric hygropyrexia syndrome]

Splenogastric hygropyrexia syndrome, a common syndome in clinical practice, responds well to the therapy of traditional Chinese medicine (TCM). In view of the complexity of TCM syndrome formation, proceeding from different aspects such as Helicobacter pylori (Hp) infection, expression of inflammatory factors, mucosal protection and change in micro-ecosystem, the authors proposed that Hp infection in gastric mucosa, nuclear factor-kappa B activation, over-expression of heat shock protein 70, and "excessive evil, dyssplenism and confliction between healthy energy and evils" due to disequilibrium between Hp and lactobacillus acidophilus in gastric mucosa and coated tongue may be the important links in the formation of Hp related gastrosis with splenogastric hygropyrexia syndrome.

Aneuploidy involving chromosome 1 may be an early predictive marker of intestinal type gastric cancer

Intestinal type gastric cancer is a significant cause of mortality, therefore a better understanding of its molecular basis is required. We assessed if either aneuploidy or activity of the oncogenic transcription factor nuclear factor kappa B (NF-kappaB), increased incrementally during pre-malignant gastric histological progression and also if they correlated with each other in patient samples, as they are both induced by oxygen free radicals. In a prospective study of 54 (aneuploidy) and 59 (NF-kappaB) consecutive patients, aneuploidy was assessed by interphase fluorescent in situ hybridisation (FISH) for chromosome 1. NF-kappaB was assessed by expression of interleukin-8 (IL-8), and in a subset, by immunohistochemistry (IHC) for active p65. Aneuploidy levels increased incrementally across the histological series. 2.76% of cells with normal histology (95% CI, 2.14-3.38%) showed background levels of aneuploidy, this increased to averages of 3.78% (95% CI, 3.21-4.35%), 5.89% (95% CI, 3.72-8.06%) and 7.29% (95% CI, 4.73-9.85%) of cells from patients with gastritis, Helicobacter pylori positive gastritis and atrophy/intestinal metaplasia (IM) respectively. IL-8 expression was only increased in patients with current H. pylori infection. NF-kappaB analysis showed some increased p65 activity in inflamed tissues. IL-8 expression and aneuploidy level were not linked in individual patients. Aneuploidy levels increased incrementally during histological progression; were significantly elevated at very early stages of neoplastic progression and could well be linked to cancer development and used to assess cancer risk. Reactive oxygen species (ROS) induced in early gastric cancer are presumably responsible for the stepwise accumulation of this particular mutation, i.e. aneuploidy. Hence, aneuploidy measured by fluorescent in situ hybridisation (FISH) coupled to brush cytology, would be worthy of consideration as a predictive marker in gastric cancer and could be clinically useful in pre-malignant disease to stratify patients by their cancer risk.