Helicobacter pylori interacts with the human single-domain trefoil protein TFF1

Soluble Human Lectins at the Host-Microbe Interface

Human lectins are integral to maintaining microbial homeostasis on the skin, in the blood, and at mucosal barriers. These proteins can recognize microbial glycans and inform the host about its microbial status. In accordance with their roles, their production can vary with tissue type. They also can have unique structural and biochemical properties, and they can influence microbial colonization at sites proximal and distal to their tissue of origin. In line with their classification as innate immune proteins, soluble lectins have long been studied in the context of acute infectious disease, but only recently have we begun to appreciate their roles in maintaining commensal microbial communities (i.e., the human microbiota). This review provides an overview of soluble lectins that operate at host-microbe interfaces, their glycan recognition properties, and their roles in physiological and pathological mechanisms.

Mechanisms of cellular crosstalk in the gastric tumor microenvironment are mediated by YAP1 and STAT3

Deregulation of the Hippo pathway is a driver for cancer progression and treatment resistance. In the context of gastric cancer, YAP1 is a biomarker for poor patient prognosis. Although genomic tumor profiling provides information of Hippo pathway activation, the present study demonstrates that inhibition of Yap1 activity has anti-tumor effects in gastric tumors driven by oncogenic mutations and inflammatory cytokines. We show that Yap1 is a key regulator of cell metabolism, proliferation, and immune responses in normal and neoplastic gastric epithelium. We propose that the Hippo pathway is targetable across gastric cancer subtypes and its therapeutic benefits are likely to be mediated by both cancer cell-intrinsic and -extrinsic mechanisms.

The oncogenic mechanisms of the Janus kinase-signal transducer and activator of transcription pathway in digestive tract tumors

Digestive tract tumors are heterogeneous and involve the dysregulation of multiple signaling pathways. The Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway plays a notable role in the oncogenesis of digestive tract tumors. Typically activated by pro-inflammatory cytokines, it regulates important biological processes, such as cell growth, differentiation, apoptosis, immune responses, and inflammation. The aberrant activation of this pathway manifests in different forms, including mutations in JAKs, overexpression of cytokine receptors, and sustained STAT activation, and contributes to promoting the malignant characteristics of cancer cells, including uncontrolled proliferation, resistance to apoptosis, enhanced invasion and metastasis, angiogenesis, acquisition of stem-like properties, and drug resistance. Numerous studies have shown that aberrant activation of the JAK-STAT pathway is closely related to the development and progression of digestive tract tumors, contributing to tumor survival, angiogenesis, changes in the tumor microenvironment, and even immune escape processes. In addition, this signaling pathway also affects the sensitivity of digestive tract tumors to chemotherapy and targeted therapy. Therefore, it is crucial to comprehensively understand the oncogenic mechanisms underlying the JAK-STAT pathway in order to develop effective therapeutic strategies against digestive tract tumors. Currently, several JAK-STAT inhibitors are undergoing clinical and preclinical trials as potential treatments for various human diseases. However, further investigation is required to determine the role of this pathway, as well as the effectiveness and safety of its inhibitors, especially in the context of digestive tract tumors. In this review, we provide an overview of the structure, classic activation, and negative regulation of the JAK-STAT pathway. Furthermore, we discuss the pathogenic mechanisms of JAK-STAT signaling in different digestive tract tumors, with the aim of identifying potential novel therapeutic targets. Video Abstract.

Organoid-Based Human Stomach Micro-Physiological System to Recapitulate the Dynamic Mucosal Defense Mechanism

Several stomach diseases are attributed to the dysregulation of physiological function of gastric mucosal barrier by pathogens. Gastric organoids are a promising tool to develop treatment strategies for gastric infections. However, their functional features of in vivo gastric mucosal barrier and host-microbe interactions are limited due to the lack of physiological stimuli. Herein, a human stomach micro-physiological system (hsMPS) with physiologically relevant gastric mucosal defense system is described based on the combination of organoid and MPS technology. A fluid flow enhanced epithelial-mesenchymal interaction in the hsMPS enables functional maturation of gastric epithelial cells, which allows for the recreation of mesh-like mucus layer containing high level of mucus protective peptides and well-developed epithelial junctional complexes. Furthermore, gastroprotection mechanisms against Helicobacter pylori (H. pylori) are successfully demonstrated in this system. Therefore, hsMPS represents a new in vitro tool for research where gastric mucosal defense mechanism is pivotal for developing therapeutic strategies.

IFNγ-dependent silencing of TFF1 during Helicobacter pylori infection

Chronic Helicobacter pylori infection is the leading cause of intestinal-type adenocarcinoma, as prolonged Helicobacter colonization triggers chronic active gastritis, which may evolve into adenocarcinoma of the intestinal type. In this environment, cytokines play a significant role in determining the evolution of the infection. In combination with other factors (genetic, environmental and nutritional), the pro-inflammatory response may trigger pro-oncogenic mechanisms that lead to the silencing of tumour-suppressor genes, such as trefoil factor 1 (TFF1). The latter is known to play a protective role by maintaining the gastric mucosa integrity and retaining H. pylori in the mucus layer, preventing the progression of infection and, consequently, the development of gastric cancer (GC). Since TFF1 expression is reduced during chronic Helicobacter infection with a loss of gastric mucosa protection, we investigated the molecular pathways involved in this reduction. Specifically, we evaluated the effect of some pro-inflammatory cytokines on TFF1 regulation in GC and primary gastric cells by RT-qPCR and luciferase reporter assay analyses and the repressor role of the transcription factor C/EBPβ, overexpressed in gastric-intestinal cancer. Our results show that, among several cytokines, IFNγ stimulates C/EBPβ expression, which acts as a negative regulator of TFF1 by binding its promoter at three different sites.

The role of mechanosensitive Piezo1 channel in diseases

Mechanotransduction is associated with organ development and homoeostasis. Piezo1 and Piezo2 are novel mechanosensitive ion channels (MSCs) in mammals. MSCs are membrane proteins that are critical for the mechanotransduction of living cells. Current studies have demonstrated that the Piezo protein family not only functions in volume regulation, cellular migration, proliferation, and apoptosis but is also important for human diseases of various systems. The complete loss of Piezo1 and Piezo2 function is fatal in the embryonic period. This review summarizes the role of Piezo1 in diseases of different systems and perspectives potential treatments related to Piezo1 for these diseases.

An aqueous extract from Artemisia capillaris inhibits acute gastric injury through mucosal stabilization

BACKGROUND

Artemisia capillaris is among the most abundantly used traditional medicines, utilized in East Asia to treat diverse illnesses, including gastrointestinal tract diseases. We previously reported that an aqueous extract of A. capillaris (AEAC) inhibited gastric inflammation induced by HCl/ethanol via reactive oxygen species scavenging and NF-κB downregulation. To date, the pharmacological potential of AEAC for promoting mucosal integrity has not been studied.

RESULTS

Here, we report that a single treatment with AEAC increased mucus production, and repeated administration of AEAC abolished HCl/ethanol-induced mucosal injury in vivo. Single- and multiple-dose AEAC treatments measurably increased the expression of mucosal stabilizing factors in vivo, including mucin (MUC) 5 AC, MUC6, and trefoil factor (TFF) 1 and TFF2 (but not TFF3). AEAC also induced mucosal stabilizing factors in both SNU-601 cells and RGM cells through phosphorylation of extracellular signal-regulated kinases.

CONCLUSION

Taken together, our results suggest that AEAC protects against HCl/ethanol-induced gastritis by upregulating MUCs and TFFs and stabilizing the mucosal epithelium. © 2021 Society of Chemical Industry.

TFF1 Induces Aggregation and Reduces Motility of Helicobacter pylori

Gastric cancer is considered one of the most common malignancies in humans and Helicobacter pylori infection is the major environmental risk factor of gastric cancer development. Given the high spread of this bacterium whose infection is mostly asymptomatic, H. pylori colonization persists for a long time, becoming chronic and predisposing to malignant transformation. The first defensive barrier from bacterial infection is constituted by the gastric mucosa that secretes several protective factors, among which is the trefoil factor 1 (TFF1), that, as mucin 5AC, binds the bacterium. Even if the protective role of TFF1 is well-documented, the molecular mechanisms that confer a beneficial function to the interaction among TFF1 and H. pylori remain still unclear. Here we analyze the effects of this interaction on H. pylori at morphological and molecular levels by means of microscopic observation, chemiotaxis and motility assays and real-time PCR analysis. Our results show that TFF1 favors aggregation of H. pylori and significantly slows down the motility of the bacterium across the mucus. Such aggregates significantly reduce both flgE and flaB gene transcription compared with bacteria not incubated with TFF1. Finally, our results suggest that the interaction between TFF1 and the bacterium may explain the frequent persistence of H. pylori in the human host without inducing disease.

Chemical synthesis of human trefoil factor 1 (TFF1) and its homodimer provides novel insights into their mechanisms of action

TFF1 is a key peptide for gastrointestinal protection and repair. Its molecular mechanism of action remains poorly understood with synthetic intractability a recognised bottleneck. Here we describe the synthesis of TFF1 and its homodimer and their interactions with mucins and Helicobacter pylori. Synthetic access to TFF1 is an important milestone for probe and therapeutic development.

Structure, Function, and Therapeutic Potential of the Trefoil Factor Family in the Gastrointestinal Tract

Trefoil factor family peptides (TFF1, TFF2, and TFF3) are key players in protecting, maintaining, and repairing the gastrointestinal tract. Accordingly, they have the therapeutic potential to treat and prevent a variety of gastrointestinal disorders associated with mucosal damage. TFF peptides share a conserved motif, including three disulfide bonds that stabilize a well-defined three-loop-structure reminiscent of a trefoil. Although multiple functions have been described for TFF peptides, their mechanisms at the molecular level remain poorly understood. This review presents the status quo of TFF research relating to gastrointestinal disorders. Putative TFF receptors and protein partners are described and critically evaluated. The therapeutic potential of these peptides in gastrointestinal disorders where altered mucosal biology plays a crucial role in the underlying etiology is discussed. Finally, areas of investigation that require further research are addressed. Thus, this review provides a comprehensive update on TFF literature as well as guidance toward future research to better understand this peptide family and its therapeutic potential for the treatment of gastrointestinal disorders.

Muc5ac null mice are predisposed to spontaneous gastric antro-pyloric hyperplasia and adenomas coupled with attenuated H. pylori-induced corpus mucous metaplasia

Gastric cancer (GC) is the third leading cause of cancer-related deaths worldwide and is strongly associated with chronic Helicobacter pylori (Hp) infection. The ability of Hp to closely adhere to the gastric surface protective mucous layer containing mucins (MUC in humans and Muc in animals), primarily Muc5ac, is integral in the stepwise pathogenesis from gastritis to cancer. To probe the role of Muc5ac in Hp-induced gastric pathology, Muc5ac^-/- and Muc5ac^+/+ (WT) mice were experimentally infected with Hp Sydney strain (SS1). At 16 weeks and 32 weeks post infection (wpi), groups of mice were euthanized and evaluated for the following: gastric histopathological parameters, immunohistochemical expression of mucins (Muc5ac, Muc1, Muc2), Trefoil factor family proteins (Tff1 and Tff2), Griffonia (Bandeiraea) simplicifolia lectin II (GSL II) (mucous metaplasia marker) and Clusterin (Spasmolytic Polypeptide Expressing Metaplasia (SPEM) marker), Hp colonization density by qPCR and gastric cytokine mRNA levels. Our results demonstrate that Muc5ac^-/- mice developed spontaneous antro-pyloric proliferation, adenomas and in one case with neuroendocrine differentiation; these findings were independent of Hp infection along with strong expression levels of Tff1, Tff2 and Muc1. Hp-infected Muc5ac^-/- mice had significantly lowered gastric corpus mucous metaplasia at 16 wpi and 32 wpi (P = 0.0057 and P = 0.0016, respectively), with a slight reduction in overall gastric corpus pathology. GSII-positive mucous neck cells were decreased in Hp-infected Muc5ac^-/- mice compared to WT mice and clusterin positivity was noted within metaplastic glands in both genotypes following Hp infection. Additionally, Hp colonization densities were significantly higher in Muc5ac^-/- mice compared to WT at 16 wpi in both sexes (P = 0.05) along with a significant reduction in gastric Tnfα (16 wpi-males and females, P = 0.017 and P = 0.036, respectively and 32 wpi-males only, P = 0.025) and Il-17a (16 wpi-males) (P = 0.025). Taken together, our findings suggest a protective role for MUC5AC/Muc5ac in maintaining gastric antral equilibrium and inhibiting Hp colonization and associated inflammatory pathology.

The Interaction of Helicobacter pylori with TFF1 and Its Role in Mediating the Tropism of the Bacteria Within the Stomach

Helicobacter pylori colonises the human stomach and has tropism for the gastric mucin, MUC5AC. The majority of organisms live in the adherent mucus layer within their preferred location, close to the epithelial surface where the pH is near neutral. Trefoil factor 1 (TFF1) is a small trefoil protein co-expressed with the gastric mucin MUC5AC in surface foveolar cells and co-secreted with MUC5AC into gastric mucus. Helicobacter pylori binds with greater avidity to TFF1 dimer, which is present in gastric mucus, than to TFF1 monomer. Binding of H. pylori to TFF1 is mediated by the core oligosaccharide subunit of H. pylori lipopolysaccharide at pH 5.0–6.0. Treatment of H. pylori lipopolysaccharide with mannosidase or glucosidase inhibits its interaction with TFF1. Both TFF1 and H. pylori have a propensity for binding to mucins with terminal non-reducing α- or β-linked N-acetyl-d-glucosamine or α-(2,3) linked sialic acid or Gal-3-SO₄²⁻. These findings are strong evidence that TFF1 has carbohydrate-binding properties that may involve a conserved patch of aromatic hydrophobic residues on the surface of its trefoil domain. The pH-dependent lectin properties of TFF1 may serve to locate H. pylori deep in the gastric mucus layer close to the epithelium rather than at the epithelial surface. This restricted localisation could limit the interaction of H. pylori with epithelial cells and the subsequent host signalling events that promote inflammation.

Activation of STAT3 signaling is mediated by TFF1 silencing in gastric neoplasia

TFF1, a secreted protein, plays an essential role in keeping the integrity of gastric mucosa and its barrier function. Loss of TFF1 expression in the TFF1-knockout (KO) mouse leads to a pro-inflammatory phenotype with a cascade of gastric lesions that include low-grade dysplasia, high-grade dysplasia, and adenocarcinomas. In this study, we demonstrate nuclear localization of p-STAT^Y705, with significant overexpression of several STAT3 target genes in gastric glands from the TFF1-KO mice. We also show frequent loss of TFF1 with nuclear localization of STAT3 in human gastric cancers. The reconstitution of TFF1 protein in human gastric cancer cells and 3D gastric glands organoids from TFF1-KO mice abrogates IL6-induced nuclear p-STAT3^Y705 expression. Reconstitution of TFF1 inhibits IL6-induced STAT3 transcription activity, suppressing expression of its target genes. TFF1 blocks IL6Rα-GP130 complex formation through interfering with binding of IL6 to its receptor IL6Rα. These findings demonstrate a functional role of TFF1 in suppressing gastric tumorigenesis by impeding the IL6-STAT3 pro-inflammatory signaling axis.

Trefoil factor 1 (TFF1) is a protein secreted by the gastric mucosa that protects against gastric tumourigenesis. Here, the authors show that TFF1 inhibits the oncogenic inflammatory response and IL-6-mediated STAT3 activation by interfering with the binding of IL6 to its receptor IL6Rα.

Binding of Helicobacter pylori to Human Gastric Mucins Correlates with Binding of TFF1

Helicobacter pylori binds to the gastric mucin, MUC5AC, and to trefoil factor, TFF1, which has been shown to interact with gastric mucin. We examined the interactions of TFF1 and H. pylori with purified gastrointestinal mucins from different animal species and from humans printed on a microarray platform to investigate whether TFF1 may play a role in locating H. pylori in gastric mucus. TFF1 bound almost exclusively to human gastric mucins and did not interact with human colonic mucins. There was a strong correlation between binding of TFF1 and H. pylori to human gastric mucins, and between binding of both TFF1 and H. pylori to gastric mucins with that of Griffonia simplicifolia lectin-II, which is specific for terminal non-reducing α- or β-linked N-acetyl-d-glucosamine. These results suggest that TFF1 may help to locate H. pylori in a discrete layer of gastric mucus and hence restrain their interactions with epithelial cells.

Trefoil Factor Peptides and Gastrointestinal Function

Trefoil factor (TFF) peptides, with a 40-amino acid motif and including six conserved cysteine residues that form intramolecular disulfide bonds, are a family of mucin-associated secretory molecules mediating many physiological roles that maintain and restore gastrointestinal (GI) mucosal homeostasis. TFF peptides play important roles in response to GI mucosal injury and inflammation. In response to acute GI mucosal injury, TFF peptides accelerate cell migration to seal the damaged area from luminal contents, whereas chronic inflammation leads to increased TFF expression to prevent further progression of disease. Although much evidence supports the physiological significance of TFF peptides in mucosal defenses, the molecular and cellular mechanisms of TFF peptides in the GI epithelium remain largely unknown. In this review, we summarize the functional roles of TFF1, 2, and 3 and illustrate their action mechanisms, focusing on defense mechanisms in the GI tract.

How host regulation of Helicobacter pylori-induced gastritis protects against peptic ulcer disease and gastric cancer

The bacterial pathogen Helicobacter pylori is the etiological agent of a range of gastrointestinal pathologies including peptic ulcer disease and the major killer, gastric adenocarcinoma. Infection with this bacterium induces a chronic inflammatory response in the gastric mucosa (gastritis). It is this gastritis that, over decades, eventually drives the development of H. pylori-associated disease in some individuals. The majority of studies investigating H. pylori pathogenesis have focused on factors that promote disease development in infected individuals. However, an estimated 85% of those infected with H. pylori remain completely asymptomatic, despite the presence of pathogenic bacteria that drive a chronic gastritis that lasts many decades. This indicates the presence of highly effective regulatory processes in the host that, in most cases, keeps a check on inflammation and protect against disease. In this minireview we discuss such known host factors and how they prevent the development of H. pylori-associated pathologies.

Mouse models for gastric cancer: Matching models to biological questions

Gastric cancer is the third leading cause of cancer-related mortality worldwide. This is in part due to the asymptomatic nature of the disease, which often results in late-stage diagnosis, at which point there are limited treatment options. Even when treated successfully, gastric cancer patients have a high risk of tumor recurrence and acquired drug resistance. It is vital to gain a better understanding of the molecular mechanisms underlying gastric cancer pathogenesis to facilitate the design of new-targeted therapies that may improve patient survival. A number of chemically and genetically engineered mouse models of gastric cancer have provided significant insight into the contribution of genetic and environmental factors to disease onset and progression. This review outlines the strengths and limitations of current mouse models of gastric cancer and their relevance to the pre-clinical development of new therapeutics.

Trefoil factor 1 expression suppresses Helicobacter pylori-induced inflammation in gastric carcinogenesis

BACKGROUND

Infection with Helicobacter pylori, a high-risk factor for gastric cancer, is frequently associated with chronic inflammation through activation of nuclear factor κB (NF-κB). Trefoil factor 1 (TFF1) is a constitutively expressed protein in the stomach that has tumor-suppressor functions and plays a critical role in maintaining mucosal integrity. This study investigated the role of TFF1 in regulating the proinflammatory response to H. pylori infections.

METHODS

For in vitro studies, immunofluorescence, luciferase reporter assays, Western blots, and quantitative real-time polymerase chain reaction were performed to investigate the activation of NF-κB and its target genes in response to infections with H. pylori strains J166 and 7.13. In addition, Tff1-knockout (KO) and Tff1-wild-type mice were used for infections with the H. pylori strain called premouse Sydney strain 1.

RESULTS

The reconstitution of TFF1 expression in gastric cancer cells significantly suppressed H. pylori-mediated increases in NF-κB-p65 nuclear staining, transcriptional activity, and expression of proinflammatory cytokine genes (tumor necrosis factor α, interleukin 1β, chemokine [C-X-C motif] ligand 5, and interleukin 4 receptor) that were associated with reductions in the expression and phosphorylation of NF-κB-p65 and IκB kinase α/β proteins. The in vivo studies using the Tff1-KO mouse model of gastric neoplasia confirmed the in vitro findings. Furthermore, they demonstrated increases in chronic inflammation scores and in the frequency of invasive gastric adenocarcinoma in the Tff1-KO mice infected with H. pylori versus the uninfected Tff1-KO mice.

CONCLUSIONS

These findings underscore an important protective role of TFF1 in abrogating H. pylori-mediated inflammation, a crucial hallmark of gastric tumorigenesis. Therefore, loss of TFF1 expression could be an important step in H. pylori-mediated gastric carcinogenesis.

Motility and chemotaxis mediate the preferential colonization of gastric injury sites by Helicobacter pylori

Helicobacter pylori (H. pylori) is a pathogen contributing to peptic inflammation, ulceration, and cancer. A crucial step in the pathogenic sequence is when the bacterium first interacts with gastric tissue, an event that is poorly understood in vivo. We have shown that the luminal space adjacent to gastric epithelial damage is a microenvironment, and we hypothesized that this microenvironment might enhance H. pylori colonization. Inoculation with 10⁶H. pylori (wild-type Sydney Strain 1, SS1) significantly delayed healing of acetic-acid induced ulcers at Day 1, 7 and 30 post-inoculation, and wild-type SS1 preferentially colonized the ulcerated area compared to uninjured gastric tissue in the same animal at all time points. Gastric resident Lactobacillus spp. did not preferentially colonize ulcerated tissue. To determine whether bacterial motility and chemotaxis are important to ulcer healing and colonization, we analyzed isogenic H. pylori mutants defective in motility (ΔmotB) or chemotaxis (ΔcheY). ΔmotB (10⁶) failed to colonize ulcerated or healthy stomach tissue. ΔcheY (10⁶) colonized both tissues, but without preferential colonization of ulcerated tissue. However, ΔcheY did modestly delay ulcer healing, suggesting that chemotaxis is not required for this process. We used two-photon microscopy to induce microscopic epithelial lesions in vivo, and evaluated accumulation of fluorescently labeled H. pylori at gastric damage sites in the time frame of minutes instead of days. By 5 min after inducing damage, H. pylori SS1 preferentially accumulated at the site of damage and inhibited gastric epithelial restitution. H. pylori ΔcheY modestly accumulated at the gastric surface and inhibited restitution, but did not preferentially accumulate at the injury site. H. pylori ΔmotB neither accumulated at the surface nor inhibited restitution. We conclude that bacterial chemosensing and motility rapidly promote H. pylori colonization of injury sites, and thereby biases the injured tissue towards sustained gastric damage.

H. pylori is a disease-causing bacterium that commonly infects the human stomach in both developed and underdeveloped countries. Infected individuals can develop digestive diseases, including stomach inflammation, peptic ulcer, and cancer. There has been only limited investigation into the events when H. pylori first interacts with stomach tissue. Using anesthetized mice in which we have induced microscopic damage to the stomach surface, we find that H. pylori is able to rapidly detect and navigate towards this damage site. Within minutes, bacterial accumulation slows repair of the damage. This is the earliest event of H. pylori pathogenesis that has been reported in vivo. We further define that this pathology is due to the bacterial accumulation at damage sites and that this also occurs in a model of larger stomach damage (ulceration). The broader implications of our work are that even sub-clinical insults to the stomach that occur in daily life (damage from grinding of food, ingestion of alcohol, taking an aspirin) can potentially attract H. pylori and not only slow repair of any existing damage, but maybe also provide an initiation site that can start the pathogenic sequence of stomach disease caused by H. pylori.

Piezo1 is as a novel trefoil factor family 1 binding protein that promotes gastric cancer cell mobility in vitro

BACKGROUND

Trefoil factor family 1 (TFF1) is a member of the TFF-domain peptide family involved in epithelial restitution and cell motility. Recently, we screened Piezo1 as a candidate TFF1-binding protein.

AIM

We aimed to confirm Piezo1 as a novel TFF1 binding protein and to assess the role of this interaction in mediating gastric cancer cell mobility.

METHODS

This interaction was confirmed by co-immunoprecipitation and co-localisation of TFF1 and Piezo1 in GES-1 cells. We used stable RNA interference to knockdown Piezo1 protein expression and restored the expression of TFF1 in the gastric cancer cell lines SGC-7901 and BGC-823. Cell motility was evaluated using invasion assay and migration assay in vitro. The expression levels of the integrin subunits β1, β5, α1 as well as the expression of β-catenin and E-cadherin were detected by Western blot.

RESULTS

We demonstrate that TFF1, but not TFF2 or TFF3, bind to and co-localize with Piezo1 in the cytoplasm in vitro. TFF1 interacts with the C-terminal portion of the Piezo1 protein. Wound healing and trans-well assays demonstrated that the restored expression of TFF1 promoted cell mobility in gastric cancer cells, and this effect was attenuated by the knockdown of Piezo1. Western blots demonstrated the decreased expression of integrin β1 in Piezo1-knockdown cells.

CONCLUSIONS

Our data demonstrate that Piezo1 is a novel TFF1 binding protein that is important for TFF1-mediated cell migration and suggest that this interaction may be a therapeutic target in the invasion and metastasis of gastric cancer.

Factors that mediate colonization of the human stomach by Helicobacter pylori

Helicobacter pylori (H. pylori) colonizes the stomach of humans and causes chronic infection. The majority of bacteria live in the mucus layer overlying the gastric epithelial cells and only a small proportion of bacteria are found interacting with the epithelial cells. The bacteria living in the gastric mucus may act as a reservoir of infection for the underlying cells which is essential for the development of disease. Colonization of gastric mucus is likely to be key to the establishment of chronic infection. How H. pylori manages to colonise and survive in the hostile environment of the human stomach and avoid removal by mucus flow and killing by gastric acid is the subject of this review. We also discuss how bacterial and host factors may together go some way to explaining the susceptibility to colonization and the outcome of infection in different individuals. H. pylori infection of the gastric mucosa has become a paradigm for chronic infection. Understanding of why H. pylori is such a successful pathogen may help us understand how other bacterial species colonise mucosal surfaces and cause disease.

Comparative adherence of Candida albicans and Candida dubliniensis to human buccal epithelial cells and extracellular matrix proteins

Candida albicans and Candida dubliniensis are very closely related pathogenic yeast species. Despite their close relationship, C. albicans is a far more successful colonizer and pathogen of humans. The purpose of this study was to determine if the disparity in the virulence of the two species is attributed to differences in their ability to adhere to human buccal epithelial cells (BECs) and/or extracellular matrix proteins. When grown overnight at 30°C in yeast extract peptone dextrose, genotype 1 C. dubliniensis isolates were found to be significantly more adherent to human BECs than C. albicans or C. dubliniensis genotypes 2-4 (P < 0.001). However, when the yeast cells were grown at 37°C, no significant difference between the adhesion of C. dubliniensis genotype 1 and C. albicans to human BECs was observed, and C. dubliniensis genotype 1 and C. albicans adhered to BECs in significantly greater numbers than the other C. dubliniensis genotypes (P < 0.001). Using surface plasmon resonance analysis, C. dubliniensis isolates were found to adhere in significantly greater numbers than C. albicans to type I and IV collagen, fibronectin, laminin, vitronectin, and proline-rich peptides. These data suggest that C. albicans is not more adherent to epithelial cells or matrix proteins than C. dubliniensis and therefore other factors must contribute to the greater levels of virulence exhibited by C. albicans.

Copper promotes TFF1-mediated Helicobacter pylori colonization

The trefoil peptides (TFF1, TFF2 and TFF3) are a family of small highly conserved proteins that play an essential role in epithelial regeneration within the gastrointestinal tract, where they are mainly expressed. TFF1 expression is strongly induced after mucosal injury and it has been proposed that tff1 functions as a gastric tumor suppressor gene. Several studies confirm that tff1 expression is frequently lost in gastric cancer because of deletions, mutations or methylation of the tff1 promoter. Infection by Helicobacter pylori (H. pylori) results in chronic gastritis and it can lead to the development of gastric or duodenal ulcers. Moreover, it is known that there is a strong link to the development of gastric cancer. It has been shown that H. pylori interacts with the dimeric form of TFF1 and that the rough form of lipopolysaccharide mediates this interaction. We have previously reported that the carboxy-terminus of TFF1 is able to specifically bind copper ions (Cu) and that Cu binding favours the homodimerization of the peptide, thus enhancing its motogenic activity. Here, we report that the Cu-TFF1 cuprocomplex promotes adherence of H. pylori to epithelial cells. Adherence of H. pylori to gastric adenocarcinoma cells, AGS AC1 cells, induced to hyper-express TFF1 was enhanced compared to noninduced cells. Copper further promoted this interaction. A H. pylori mutant unable to bind TFF1 did not show enhanced infection of induced cells. Cu treatment induced a thickening of the mucus layer produced by the colorectal adenocarcinoma mucus secreting, goblet cells, HT29-E12 and promoted H. pylori colonisation. Finally, SPR analysis shows that the C-terminus of TFF1, involved in the binding of copper, is also able to selectively bind H. pylori RF-LPS.

Promoter polymorphisms in trefoil factor 2 and trefoil factor 3 genes and susceptibility to gastric cancer and atrophic gastritis among Chinese population

The polymorphisms in trefoil factor (TFF) gene family that protect gastrointestinal epithelium might influence individual vulnerability to gastric cancer (GC) and atrophic gastritis. We used the Sequenom MassARRAY platform to identify the genotypes of TFF2 rs3814896 and TFF3 rs9981660 polymorphisms in 478 GC patients, 652 atrophic gastritis patients, and 724 controls. For the TFF2 rs3814896 polymorphism, in the subgroup aged ≤ 50 years, we found that AG+GG genotypes were associated with a 0.746-fold decreased risk of atrophic gastritis [p=0.023, 95% confidence interval (CI)=0.580-0.960], a 0.626-fold decreased risk of GC (p=0.005, 95% CI=0.451-0.868), and a 0.663-fold decreased risk of diffuse-type GC (p=0.034, 95% CI=0.452-0.970) compared with the common AA genotype. For the TFF3 rs9981660 polymorphism, in the male subgroup, individuals with variant AG+AA genotype were associated with a 0.761-fold decreased risk of diffuse-type GC compared with the common GG genotype (p=0.043, 95% CI=0.584-0.992). Additionally, we found that in subjects aged ≤ 50 years compared with common AA genotype, TFF2 rs3814896 AG+GG genotypes were associated with increased TFF2 mRNA levels in the total gastric cancer specimens and in the diffuse-type gastric cancer specimens; and in males aged ≤ 50 years compared with common GG genotype, TFF3 rs9981660 AA+AG genotypes were associated with TFF3 mRNA levels in diffuse-type gastric cancer tissues and their corresponding non-cancerous tissues. To our knowledge, this is the first report of an association between the TFF2 rs3814896 AG+GG genotypes and decreased risks of GC, diffuse-type GC, and atrophic gastritis in younger people aged ≤ 50 years, and an association between TFF3 rs9981660 AG+AA genotype and decreased risk of diffuse-type GC in men. Moreover, we found that TFF2 rs3814896 AG+GG genotypes in people aged ≤ 50 years and TFF3 rs9981660 AG+AA genotypes in younger males with diffuse-type GC were associated with higher levels of TFF2 and TFF3 mRNA respectively.

Mouse models of gastric cancer

Animal models have greatly enriched our understanding of the molecular mechanisms of numerous types of cancers. Gastric cancer is one of the most common cancers worldwide, with a poor prognosis and high incidence of drug-resistance. However, most inbred strains of mice have proven resistant to gastric carcinogenesis. To establish useful models which mimic human gastric cancer phenotypes, investigators have utilized animals infected with Helicobacter species and treated with carcinogens. In addition, by exploiting genetic engineering, a variety of transgenic and knockout mouse models of gastric cancer have emerged, such as INS-GAS mice and TFF1 knockout mice. Investigators have used the combination of carcinogens and gene alteration to accelerate gastric cancer development, but rarely do mouse models show an aggressive and metastatic gastric cancer phenotype that could be relevant to preclinical studies, which may require more specific targeting of gastric progenitor cells. Here, we review current gastric carcinogenesis mouse models and provide our future perspectives on this field.

Gastrokines: stomach-specific proteins with putative homeostatic and tumor suppressor roles

During the past decade, a new family of stomach-specific proteins has been recognized. Known as "gastrokines" (GKNs), these secreted proteins are products of gastric mucus-producing cell lineages. GKNs are highly conserved in physical structure, and emerging data point to convergent functions in the modulation of gastric mucosal homeostasis and inflammation. While GKNs are highly prevalent in the normal stomach, frequent loss of GKN expression in gastric cancers, coupled with established antiproliferative activity, suggests putative tumor suppressor roles. Conversely, ectopic expression of GKNs in reparative lesions of Crohn's disease alludes to additional activity in epithelial wound healing and/or repair. Modes of action remain unsolved, but the recent demonstration of a GKN2-trefoil factor 1 heterodimer implicates functional interplay with trefoil factors. This review aims to provide a historical account of GKN biology and encapsulate the rapidly accumulating evidence supporting roles in gastric epithelial homeostasis and tumor suppression.

Trefoil factor 1 suppression of E-CADHERIN enhances prostate carcinoma cell invasiveness and metastasis

Metastasis is the primary mediator of prostate cancer (PCA) lethality and poses a significant clinical obstacle. The identification of factors involved in the metastasis of PCA is imperative. We demonstrate herein that trefoil factor 1 (TFF1) promotes PCA cell migration and invasion in vitro and metastasis in vivo. The capacity of TFF1 to enhance cell migration/invasion is mediated by transcriptional repression of E-CADHERIN. Consideration of targeted inhibition of TFF1 to prevent metastasis of prostate carcinoma is warranted.

The interaction of Helicobacter pylori with the adherent mucus gel layer secreted by polarized HT29-MTX-E12 cells

Helicobacter pylori colonises the gastric mucosa of humans. The majority of organisms live in mucus. These organisms are an important reservoir for infection of the underlying epithelium. Cell culture models for H. pylori infection do not normally possess a mucus layer. The interaction of H. pylori with TFF1, a member of the trefoil factor family found in gastric mucin, is mediated by lipopolysaccharide. To test the hypothesis that the interaction of H. pylori with TFF1 promotes mucus colonization we characterised the interaction of H. pylori with a mucus secreting cell line, HT29-MTX-E12. An isogenic mutant of H. pylori with truncated core oligosaccharides was produced and binding to TFF1 and ability to colonise HT29-MTX-E12 cells determined. The adherent mucus layer of HT29-MTX-E12 cells contained the gastric mucin MUC5AC and trefoil factors, TFF1 and TFF3. H. pylori was found within the mucus layer in discrete clusters and in close association with TFF1. It also interacted with the membrane bound mucin MUC1 and replicated when co-cultured with the cells. An isogenic mutant of H. pylori with a truncated LPS core did not interact with TFF1, and colonization of HT29-MTX-E12 cells was reduced compared to the wild-type strain (p<0.05). Preincubation of cells with wild type LPS but not with truncated LPS resulted in reduced colonization by H. pylori. These results demonstrate that the interaction of TFF1 with H. pylori is important for colonization of gastric mucus and the core oligosaccharide of H. pylori LPS is critical for this interaction to occur. HT29-MTX-E12 cells are a useful system with which to study the interaction of bacteria with mucosal surfaces and the effect of such interactions on mediating colonization.

Defense and adaptation: the complex inter-relationship between Campylobacter jejuni and mucus

Mucus colonization is an essential early step toward establishing successful infection and disease by mucosal pathogens. There is an emerging literature implicating specific mucin sub-types and mucin modifications in protecting the host from Campylobacter jejuni infection. However, mucosal pathogens have evolved sophisticated mechanisms to breach the mucus layer and C. jejuni in particular appears to harbor specific adaptations to better colonize intestinal mucus. For example, components of mucus are chemotactic for C. jejuni and the rheological properties of mucus promote motility of the organism. Furthermore, recent studies demonstrate that mucins modulate the pathogenicity of C. jejuni in a species-specific manner and likely help determine whether these bacteria become pathogenic (as in humans), or adopt a commensal mode of existence (as in chickens and other animals). This review focuses on recent advances in understanding the complex interplay between C. jejuni and components of the mucus layer.

Murine models of H. pylori-induced gastritis and gastric adenocarcinoma

Laboratory mice have become one of the best animal species for mechanistic studies in gastrointestinal research. Their abundant genetic information, the way of causing carcinogenesis easily by transgenic and gene knockout techniques, limited effort in time and costs, and their practicability provide advantages over other animal models. Meanwhile, several murine practical models have been established for the investigation of the initiation, expansion, and progression of gastritis and gastric carcinoma, for assessing the effects of bacterial, genetic and environmental factors, and for evaluating therapeutic and preventive strategies in gastric diseases. This article gives a review of murine models of gastritis and gastric cancer, placing emphasis on the models associated with Helicobacter pylori infection and techniques used in our laboratory. We discuss matters of murine gastric anatomy, as well as techniques of infection, tissue preparation, and histology.

Gastroduodenal mucosal defense

PURPOSE OF REVIEW

The gastroduodenum has multiple means by which it resists injury from intrinsic and extrinsic factors, including gastric acid, nonsteroidal anti-inflammatory drugs, and Helicobacter pylori. We review recent insights into the mechanisms by which the gastroduodenum resists injury and discuss factors contributing to defensive failure.

RECENT FINDINGS

Duodenal bicarbonate secretion, a primary defensive mechanism, is mediated by the downregulated in adenoma anion exchanger and is stimulated by estrogens. Nonsteroidal anti-inflammatory drug gastric damage is dependent on toll-like receptor signaling. Portal hypertensive gastropathy impairs extracellular signal-regulated kinase 1/2 phosphorylation, increasing oxidative stress. H. pylori-induced peptic ulcer disease is associated with inadequate regulatory T cell responses.

SUMMARY

Enhanced understanding of the mechanisms of gastroduodenal defense and injury provides new insight into potential therapeutic targets, which contributes towards the development of more well tolerated and more effective therapies.

Trefoil factor-1 (TFF1) enhances oncogenicity of mammary carcinoma cells

The functional role of autocrine trefoil factor-1 (TFF1) in mammary carcinoma has not been previously elucidated. Herein, we demonstrate that forced expression of TFF1 in mammary carcinoma cells resulted in increased total cell number as a consequence of increased cell proliferation and survival. Forced expression of TFF1 enhanced anchorage-independent growth and promoted scattered cell morphology with increased cell migration and invasion. Moreover, forced expression of TFF1 increased tumor size in xenograft models. Conversely, RNA interference-mediated depletion of TFF1 in mammary carcinoma cells significantly reduced anchorage-independent growth and migration. Furthermore, neutralization of secreted TFF1 protein by polyclonal antibody decreased mammary carcinoma cell viability in vitro and resulted in regression of mammary carcinoma xenografts. We have therefore demonstrated that TFF1 possesses oncogenic functions in mammary carcinoma cells. Functional antagonism of TFF1 can therefore be considered as a novel therapeutic strategy for mammary carcinoma.

Unraveling mechanisms of action of probiotics

Probiotics are defined as living organisms that, when administered in sufficient numbers, are of benefit to the host. Current evidence indicates that varying probiotic strains mediate their effects by a variety of different effects that are dependent on the dosage employed as well as the route and frequency of delivery. Some probiotics act in the lumen of the gut by elaborating antibacterial molecules such as bacteriocins; others enhance the mucosal barrier by increasing the production of innate immune molecules, including goblet cell-derived mucins and trefoil factors and defensins produced by intestinal Paneth cells; and other probiotics mediate their beneficial effects by promoting adaptive immune responses (secretory immune globulin A, regulatory T cells, interleukin-10). Some probiotics have the capacity to activate receptors in the enteric nervous system, which could be used to promote pain relief in the setting of visceral hyperalgesia. Future development of the effective use of probiotics in treating various gastroenterological disorders in human participants should take advantage of this new knowledge. The creation of novel formulations of probiotics could be directed to effectively target certain mechanisms of actions that are altered in specific disease states.

Gastric mucus alterations associated with murine Helicobacter infection

The C57BL/6 mouse has been shown to develop gastric adenocarcinoma after Helicobacter felis infection. This model was used to determine whether mucin and trefoil factor (TFF) expression after infection was altered in a similar fashion to the changes seen in the protective gastric mucus layer of the human stomach after H. pylori infection. Our results indicate that this mouse model mimics many of the changes seen after human H. pylori infection, including increased expression of muc4 and muc5b and loss of muc5ac. These alterations in mucin expression occurred as early as 4 weeks postinfection, before the development of significant mucous metaplasia or gastric dysplasia. The decrease in muc5ac expression occurred only in the body of the stomach and was not secondary to the adaptive immune response to infection, because a similar decrease in expression was seen after infection of B6.Rag-1(-/-) mice, which lack B and T cells. Intriguingly, the increased expression of Muc4 and Muc5b in infected C57BL/6 mice was not seen in the infected B6.Rag-1(-/-) mice. Because B6.Rag-1(-/-) mice do not develop gastric pathology after H. felis infection, these findings point to the potential role of Muc4 and Muc5b in disease progression. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.

Helicobacter pylori lipopolysaccharide interacts with TFF1 in a pH-dependent manner

BACKGROUND & AIMS

Little is known about how bacteria establish chronic infections of mucosal surfaces. Helicobacter pylori (H. pylori), a chronic pathogen that lives in the gastric mucosa of humans, interacts with the trefoil factor family (TFF) protein TFF1, which is found in gastric mucus. We aimed to characterize the interaction of H. pylori with TFF1 and to assess the role of this interaction in mediating colonization.

METHODS

Subcellular fractions of H. pylori were immobilized and then probed with TFF1, TFF2, or TFF3. The effect of glycosidases and preincubation with monosaccharides on the interaction and binding of TFF1 to a H. pylori adhesin was assessed. The interaction between H. pylori adhesin and TFF1 was characterized using surface plasmon resonance, flow cytometry, nondenaturing polyacrylamide gel electrophoresis, coimmunofluoresence, and incubation with tissue sections.

RESULTS

The H. pylori core oligosaccharide portion (rough form) of lipopolysaccharide (RF-LPS) bound to TFF1 and to a lesser extent TFF3; this interaction was inhibited by incubation of RF-LPS with mannosidase, glucosidase, or mixed monosaccharides. TFF1 also bound to human serum albumin-conjugated mannose and glucose. The optimum pH for binding was 5.0-6.0 for TFF1 and 7.0 for TFF3. H. pylori bound TFF1 in gastric mucus ex vivo; binding of LPS-coated latex beads to human antral gastric tissue was inhibited by TFF1.

CONCLUSIONS

TFF1 interacts specifically with H. pylori RF-LPS. The pH dependence of this interaction indicates that binding of H. pylori to TFF1 in the stomach could promote colonization of the mucus layer adjacent to the gastric epithelial surface.

Emerging therapies for the treatment of Helicobacter pylori infections

OBJECTIVE

To describe emerging therapies, such as levofloxacin, moxifloxacin, rifabutin, rifaximin, tinidazole, doxycycline, minocycline, lactoferrin, and plaunotol for the eradication of Helicobacter pylori infection.

DATA SOURCES

Relevant information was identified through a search of MEDLINE (1966-July 2008), PubMed (1955-July 2008), American Search Premier (1975-July 2008), International Pharmaceutical Abstracts (1960-2008), Science Citation Index Expanded (1996-2008), Cochrane Databases (publications archived until July 2008), and various tertiary sources using the terms Helicobacter pylori, fluoroquinolones, levofloxacin, moxifloxacin, rifabutin, rifaximin, lactoferrin, plaunotol, tinidazole, doxycycline, minocycline, faropenem, new treatments, refractory, and salvage alone or in combination.

STUDY SELECTION AND DATA EXTRACTION

Relevant information was identified and selected based on clinical relevance and value of information. In vitro and in vivo data were included if available.

DATA SYNTHESIS

Data exist supporting the use of levofloxacin or rifabutin as salvage therapies for H. pylori infection. Levofloxacin triple therapy has been recommended in the current treatment guideline, but more data are needed, especially from studies conducted in the US. A rifabutin-based regimen is better tolerated than conventional quadruple therapy, but its use is limited due to cost, hematologic adverse effects, drug interactions, and predicted development of resistance. Tinidazole appears to be an option, particularly as sequential therapy when combined with other agents; however, its use is limited by the high prevalence of nitroimidazole-resistant H. pylori strains in the US. Moxifloxacin data are limited. Data supporting the use of rifaximin, doxycycline, and minocycline are lacking or do not show benefit of these drugs over standard treatments.

CONCLUSIONS

H. pylori infection remains one of the most significant infections worldwide, and treatment failure rate with the current standard therapy continues to rise. Other treatment options should be explored to meet the emerging challenge.

The trefoil factor interacting protein TFIZ1 binds the trefoil protein TFF1 preferentially in normal gastric mucosal cells but the co-expression of these proteins is deregulated in gastric cancer

The gastric tumour suppressor trefoil protein TFF1 is present as a covalently bound heterodimer with a previously uncharacterised protein, TFIZ1, in normal human gastric mucosa. The purpose of this research was firstly to examine the molecular forms of TFIZ1 present, secondly to determine if TFIZ1 binds other proteins apart form TFF1 in vivo, thirdly to investigate if TFIZ1 and TFF1 are co-regulated in normal gastric mucosa and fourthly to determine if their co-regulation is maintained or disrupted in gastric cancer. We demonstrate that almost all human TFIZ1 is present as a heterodimer with TFF1 and that TFIZ1 is not bound to either of the other two trefoil proteins, TFF2 and TFF3. TFIZ1 and TFF1 are co-expressed by the surface mucus secretory cells throughout the stomach and the molecular forms of each protein are affected by the relative abundance of the other. TFIZ1 expression is lost consistently, early and permanently in gastric tumour cells. In contrast, TFF1 is sometimes expressed in the absence of TFIZ1 in gastric cancer cells and this expression is associated with metastasis (lymph node involvement: p = 0.007). In conclusion, formation of the heterodimer between TFIZ1 and TFF1 is a specific interaction that occurs uniquely in the mucus secretory cells of the stomach, co-expression of the two proteins is disrupted in gastric cancer and expression of TFF1 in the absence of TFIZ1 is associated with a more invasive and metastatic phenotype. This indicates that TFF1 expression in the absence of TFIZ1 expression has potentially deleterious consequences in gastric cancer.

Decreased expression of gastrokine 1 and the trefoil factor interacting protein TFIZ1/GKN2 in gastric cancer: influence of tumor histology and relationship to prognosis

PURPOSE

Transcriptional profiling showed decreased expression of gastrokine 1 (GKN1) and the related trefoil factor interacting protein (TFIZ1/GKN2) in Helicobacter pylori infection. Decreased GKN1 and GKN2 mRNA expression has been reported in gastric adenocarcinoma. We have examined GKN1 and GKN2 protein expression in a large gastric cancer series, correlated expression with tumor subtype, and evaluated their utility as prognostic biomarkers.

EXPERIMENTAL DESIGN

GKN1, GKN2, and the trefoil factors TFF1 and TFF3 were examined in tissue microarrays from 155 distal gastric adenocarcinomas. Immunohistochemical expression was correlated with clinical outcome. GKN1 and GKN2 expression was measured by real-time PCR and Western analysis in samples of gastric cancer and adjacent nonneoplastic mucosa.

RESULTS

GKN1 was lost in 78% of diffuse and 42% of intestinal cancers (P < 0.0001, diffuse versus intestinal). GKN2 expression was lost in 85% of diffuse and 54% of intestinal type cancers (P < 0.002). GKN1 and GKN2 down-regulation were confirmed by Western and real-time PCR analysis. Loss of either protein was associated with significantly worse outcome in intestinal-type tumors by univariate analysis; and GKN2 loss remained a predictor of poor outcome in multivariate analysis (P < 0.033). TFF1 was lost in >70%, and TFF3 was expressed in approximately 50% of gastric cancers.

CONCLUSIONS

Loss of GKN1 and GKN2 expression occurs frequently in gastric adenocarcinomas, especially in the diffuse subtype. GKN1 and GKN2 loss are associated with shorter overall survival in the intestinal subtype.

Quantitative analysis of the effect of Helicobacter pylori on the expressions of SOX2, CDX2, MUC2, MUC5AC, MUC6, TFF1, TFF2, and TFF3 mRNAs in human gastric carcinoma cells

OBJECTIVE

To investigate the phenotypic characters of carcinoma cells and the response of gastric epithelial cells to Helicobacter pylori (H. pylori) infection using the gastric carcinoma cell lines.

MATERIAL AND METHODS

Real-time reverse transcription-polymerase chain reaction (RT-PCR) was used to assess the effect of H. pylori infection on mRNA levels of transcription factors (SOX2 and CDX2), mucin core proteins (MUC2, MUC5AC, and MUC6), and trefoil factor family peptides (TFF) (TFF1, TFF2, and TFF3) in gastric carcinoma cells (AGS, MKN45, and KATO III cells). H. pylori ATCC 43504 and its isogenic cag pathogenicity island (PAI) deleted mutant were used.

RESULTS

These cell lines expressed mixed gastric and intestinal phenotypes. The intestinal phenotype predominated in AGS cells and gastric phenotypes in MKN45 and KATO III cells. In all three cell lines, H. pylori infection inhibited SOX2 mRNA expression, but induced the three TFFs mRNAs. In AGS cells, H. pylori induced cag PAI-dependent mRNA expression of CDX2, MUC2, MUC5AC, and MUC6. mRNA expressions of CDX2, MUC5AC, and MUC6 were inhibited in KATO III cells, whereas MUC2 mRNA expression was unchanged. In MKN45 cells, H. pylori induced the three MUCs mRNAs but inhibited CDX2 mRNA expression.

CONCLUSIONS

This study provides a useful platform for selecting appropriate cell lines to model H. pylori-related changes in the gastric epithelium that mirror the changes seen in vivo. The outcome of H. pylori infection may reflect changes in the mucus gel layer caused by altered expression of mucins and TFF peptides.

Higher gastric mucin secretion and lower gastric acid output in first-degree relatives of gastric cancer patients

BACKGROUND

Patients infected by Helicobacter pylori who have first-degree relatives with gastric cancer have an 8-fold increased risk of developing gastric cancer themselves. Mucins are high-molecular-weight glycoproteins that play a cardinal role in the protective mechanism of the gastric epithelium.

AIM

To study gastric acid and mucin secretion in dyspeptic patients with and without a family history of gastric cancer and H. pylori infection.

MATERIALS AND METHODS

Twenty-six dyspeptic patients underwent esophago-gastro-duodenoscopy, gastric biopsies, and acid and mucin secretory tests. The sample was divided by family history of gastric cancer and H. pylori status.

RESULTS

Patients who were infected by H. pylori had a significantly higher degree of inflammation than those who were not. H. pylori-positive patients with a positive family history had a lower basal and maximal gastric acid output than infected patients with no family history and noninfected controls, and a higher basal and maximal mucin output than infected patients with no family history. MUC5AC was the major mucin species expressed in gastric juice.

CONCLUSIONS

In patients with relatives with gastric cancer, H. pylori infection is associated with a more severe inflammatory reaction consisting of decreased gastric acid secretion and increased mucin secretion.

The pathogenesis of Helicobacter pylori-induced gastro-duodenal diseases

Helicobacter pylori is the main cause of peptic ulceration, distal gastric adenocarcinoma, and gastric lymphoma. Only 15% of those colonized develop disease, and pathogenesis depends upon strain virulence, host genetic susceptibility, and environmental cofactors. Virulence factors include the cag pathogenicity island, which induces proinflammatory, pro-proliferative epithelial cell signaling; the cytotoxin VacA, which causes epithelial damage; and an adhesin, BabA. Host genetic polymorphisms that lead to high-level pro-inflammatory cytokine release in response to infection increase cancer risk. Pathogenesis is dependent upon inflammation, a Th-1 acquired immune response and hormonal changes including hypergastrinaemia. Antral-predominant inflammation leads to increased acid production from the uninflamed corpus and predisposes to duodenal ulceration; corpus-predominant gastritis leads to hypochlorhydria and predisposes to gastric ulceration and adenocarcinoma. Falling prevalence of H. pylori in developed countries has led to a falling incidence of associated diseases. However, whether there are disadvantages of an H. pylori-free stomach, for example increased risk of esosphageal adenocarcinoma, remains unclear.

Helicobacter pylori gastritis, the unifying concept for gastric diseases

Helicobacter pylori infection causes a broad spectrum of clinical diseases and the clinical manifestations of the infection depend on host, environmental, and bacterial factors. These factors have an impact on the pattern and severity of gastritis and ultimately determine the clinical outcome of H. pylori infection. Better staging of gastritis may help to identify patients at risk of gastric cancer. In this article we will examine the complex interaction between host, environmental, and bacterial factors in the pathogenesis of H. pylori infection.

Binding kinetics of influenza viruses to sialic acid-containing carbohydrates

To elucidate the molecular mechanisms of transmission of influenza viruses between different host species, such as human and birds, binding properties of sialic acid-containing carbohydrates that are recognized by human and/or avian influenza viruses were characterized by the surface plasmon resonance (SPR) method. Differences in the binding of influenza viruses to three gangliosides were monitored in real-time and correlated with receptor specificity between avian and human viruses. SPR analysis with ganglioside-containing lipid bilayers demonstrated the recognition profile of influenza viruses to not only sialic acid linkages, but also core carbohydrate structures on the basis of equilibrated rate constants. Kinetic analysis showed different binding preferences to gangliosides between avian and human strains. An avian strain bound to Neu5Acalpha2-3nLc4Cer with much slower dissociation rate than its sialyl-linkage analog, Neu5Acalpha2-6nLc4Cer, on the lipid bilayer. In contrast, a human strain bound equally to both gangliosides. An avian strain, but not a human strain, also interacted with GM3 carrying a shorter carbohydrate chain. Our findings demonstrated the remarkable distinction in the binding kinetics of sialic acid-containing carbohydrates between avian and human influenza viruses on the lipid bilayer.

Bacterial factors that mediate colonization of the stomach and virulence of Helicobacter pylori

Helicobacter pylori is a Gram-negative microaerophilic organism that colonizes the gastric mucosa of humans. Helicobacter pylori is one of the most common infections in humans and results in the development of gastritis in all infected individuals, although the majority of people are asymptomatic. A subset of infected people develop serious disease including duodenal ulceration and gastric cancer. Helicobacter pylori exhibits many striking characteristics. It lives in the hostile environment of the stomach and displays a very strict host and tissue tropism. Despite a vigorous immune response, infection persists for the lifetime of the host unless eradicated with antimicrobials. Why H. pylori is so pathogenic in some individuals and not in others is unknown but is thought to be due to a variety of host, environmental and bacterial factors. In this review, some of the bacterial factors that mediate colonization of the gastric mucosa and play a role in the pathogenesis of this organism have been considered.

Up-regulation of TFF1 (pS2) expression by TNF-alpha in gastric epithelial cells

BACKGROUND AND AIM

TFF1 (pS2) is expressed at a high level in gastric epithelial cells and plays an important role in protecting the gastric mucosa. However, the regulatory mechanisms of TFF1 expression are not fully understood. The aim of this study was to investigate the effect of TNF-alpha, a representative proinflammatory cytokine, on TFF1 expression.

METHODS

MKN45 and AGS cells, derived from human gastric carcinoma, were used. Endogenous TFF1 mRNA expression was analyzed by real-time quantitative RT-PCR. The sequences of the human TFF1 promoter were cloned into the pGL3-basic vector and reporter gene assays were performed. Nuclear factor (NF)-kappaB activity was monitored using a reporter vector that contained multiple copies of NF-kappaB responsive element upstream of the luciferase gene. Interaction between NF-kappaB and TFF1 cis-element was examined by electophoretic mobility shift assay (EMSA).

RESULTS

TNF-alpha activated NF-kappaB and up-regulated endogenous TFF1 mRNA expression as well as the transcription of the TFF1 reporter genes in a dose-dependent manner. IL-1beta, another proinflammatory cytokine, also up-regulated TFF1 expression. TNF-alpha responsive element was mapped between -342 and -147 of the human TFF1 promoter and a putative NF-kappaB binding site was identified at -231. When this element was deleted, the reporter genes became almost insensitive to TNF-alpha treatment. EMSA showed binding of NF-kappaB to this element.

CONCLUSIONS

Inflammatory stimuli that activate NF-kappaB appear to up-regulate TFF1 expression in gastric epithelial cells. This mechanism may aid in the protection of the gastric mucosa under inflammatory conditions.

Campylobacter jejuni adhere to and invade chicken intestinal epithelial cells in vitro

Campylobacter jejuni is a common cause of serious diarrhoeal disease in humans, in contrast to the avian population, where exposure results in prolonged colonization at high density without disease. Colonized poultry present a significant source of infection to humans worldwide. The aim of this work was to compare the interaction of Campylobacter with primary intestinal cells from humans and poultry to identify factors that account for the divergent outcome following Campylobacter exposure. A primary intestinal cell model of Campylobacter infection was developed using cells grown from human and chicken intestinal biopsies. The cultured cells were infected with a number of strains of Campylobacter. Invasion by C. jejuni and the influence of intestinal mucus on Campylobacter internalization were studied by fluorescence microscopy and gentamicin protection assays. C. jejuni invaded primary human intestinal cells in a microtubule-, microfilament- and caveolin-dependent manner. Entry of C. jejuni into primary chicken intestinal cells also occurred. Chicken mucus, but not intestinal mucus of human origin, significantly reduced infection of primary human intestinal cells. Avian mucus appears to inhibit Campylobacter from interacting with epithelial cell surfaces.

Differentiation of the Gastric Mucosa IV. Role of trefoil peptides and IL-6 cytokine family signaling in gastric homeostasis

Gastric trefoil peptides mediate mucosal repair by stimulating cell migration, inhibiting apoptosis and inflammation, and likely augmenting the barrier function of mucus. One of these, tff1, is a gastric-specific tumor suppressor gene, which when repressed is associated with gastric cancer progression. IL-6 family cytokines play an important role in maintaining gastric homeostasis by regulating tff1 and other mediators of mucosal proliferation, inflammation, angiogenesis, and apoptosis. In this review the signaling cascades downstream of the common IL-6 cytokine family coreceptor gp130 that contribute to control of this homeostasis are described, as are the pathological outcomes of imbalancing these pathways.