Molecular Mechanisms of Helicobacter pylori Pathogenesis

Immunobiological effects of lipopolysaccharide derived from Helicobacter pylori and influence of a proton pump inhibitor lansoprazole on human polymorphonuclear leukocytes

Helicobacter pylori colonizes the human gastric mucosa of more than half of the human population and has a unique lipopolysaccharide (LPS) structure. LPS is the most dominant and suitable pathogen-associated molecular pattern that is detected via pattern recognition receptors. Although the priming effect of H. pylori LPS on reactive oxygen species (ROS) production of PMNs is lower than that of Escherichia coli O111:B4 LPS, LPS released from H. pylori associated with antibiotics eradication therapy may activate PMNs and increase ROS production. In addition, we describe the effects of H. pylori and E. coli O111:B4 LPSs on gene expression and the anti-inflammatory effect of lansoprazole (LPZ) in human polymorphonuclear leukocytes. LPS isolated from H. pylori and E. coli O111:B4 alters toll-like receptor 2 (TLR) and TLR4 expressions similarly. However, LPS from E. coli O111:B4 and H. pylori caused a 1.8-fold and 1.5-fold increase, respectively, in CD14 expression. All LPS subtypes upregulated TNFα and IL6 expression in a concentration-dependent manner. Although E. coli O111:B4 LPS upregulated IL8R mRNA levels, H. pylori LPS did not (≦ 100 ng/mL). Gene expression levels of ITGAM demonstrated no significant change on using both LPSs. These different effects on the gene expression in PMNs may depend on variations in LPS structural modifications related to the acquired immunomodulatory properties of H. pylori LPS. Proton pump inhibitors, i.e., LPZ, are used in combination with antibiotics for the eradication therapy of H. pylori. LPZ and its acid-activated sulphenamide form AG-2000 suppress ROS production of PMNs in a dose-dependent manner. These results suggest that LPZ combination with antibiotics for H. pylori eradication reduces gastric inflammation by suppressing ROS release from PMNs.

Unravelling the role of intratumoral bacteria in digestive system cancers: current insights and future perspectives

Recently, research on the human microbiome, especially concerning the bacteria within the digestive system, has substantially advanced. This exploration has unveiled a complex interplay between microbiota and health, particularly in the context of disease. Evidence suggests that the gut microbiome plays vital roles in digestion, immunity and the synthesis of vitamins and neurotransmitters, highlighting its significance in maintaining overall health. Conversely, disruptions in these microbial communities, termed dysbiosis, have been linked to the pathogenesis of various diseases, including digestive system cancers. These bacteria can influence cancer progression through mechanisms such as DNA damage, modulation of the tumour microenvironment, and effects on the host's immune response. Changes in the composition and function within the tumours can also impact inflammation, immune response and cancer therapy effectiveness. These findings offer promising avenues for the clinical application of intratumoral bacteria for digestive system cancer treatment, including the potential use of microbial markers for early cancer detection, prognostication and the development of microbiome-targeted therapies to enhance treatment outcomes. This review aims to provide a comprehensive overview of the pivotal roles played by gut microbiome bacteria in the development of digestive system cancers. Additionally, we delve into the specific contributions of intratumoral bacteria to digestive system cancer development, elucidating potential mechanisms and clinical implications. Ultimately, this review underscores the intricate interplay between intratumoral bacteria and digestive system cancers, underscoring the pivotal role of microbiome research in transforming diagnostic, prognostic and therapeutic paradigms for digestive system cancers.

Exploring the inhibitory potential of in silico-designed small peptides on Helicobacter pylori Hp0231 (DsbK), a periplasmic oxidoreductase involved in disulfide bond formation

Introduction: Helicobacter pylori is a bacterium that colonizes the gastric epithelium, which affects millions of people worldwide. H. pylori infection can lead to various gastrointestinal diseases, including gastric adenocarcinoma and mucosa-associated lymphoid tissue lymphoma. Conventional antibiotic therapies face challenges due to increasing antibiotic resistance and patient non-compliance, necessitating the exploration of alternative treatment approaches. In this study, we focused on Hp0231 (DsbK), an essential component of the H. pylori Dsb (disulfide bond) oxidative pathway, and investigated peptide-based inhibition as a potential therapeutic strategy. Methods: Three inhibitory peptides designed by computational modeling were evaluated for their effectiveness using a time-resolved fluorescence assay. We also examined the binding affinity between Hp0231 and the peptides using microscale thermophoresis. Results and discussion: Our findings demonstrate that in silico-designed synthetic peptides can effectively inhibit Hp0231-mediated peptide oxidation. Targeting Hp0231 oxidase activity could attenuate H. pylori virulence without compromising bacterial viability. Therefore, peptide-based inhibitors of Hp0231 could be candidates for the development of new targeted strategy, which does not influence the composition of the natural human microbiome, but deprive the bacterium of its pathogenic properties.

Effect of Helicobacter pylori eradication on gastric precancerous lesions: A systematic review and meta-analysis

BACKGROUND

The question of whether eradication of Helicobacter pylori (Hp) can reverse gastric precancerous lesions, including intestinal metaplasia, remains uncertain, leading to ongoing debate. Therefore, a meta-analysis was performed to evaluate the effect of Hp eradication on gastric precancerous lesions.

MATERIALS AND METHODS

PubMed, Embase, Cochrane Library, Web of Science, Scopus database, and ClinicalTrials.gov were systematically searched from inception to April 2023 for studies that explored the impact of Hp eradication on gastric precancerous lesions. Risk ratios (RRs) and their 95% confidence intervals (95% CIs) were selected as the effect size. We used the random-effects model to assess pooled data. We also performed quality assessments, subgroup analyses, and sensitivity analyses.

RESULTS

Fifteen studies were included. Compared with placebo, Hp eradication could significantly prevent the progression of gastric precancerous lesions (RR = 0.87, 95% CI: 0.81-0.94, p < 0.01) and reverse them (RR = 1.32, 95% CI: 1.17-1.50, p < 0.01). Then, specific precancerous lesions were further explored. The progression of intestinal metaplasia was significantly prevented by Hp eradication compared to placebo or no treatment (RR = 0.80, 95% CI: 0.69-0.94, p < 0.01). Moreover, compared with placebo or no treatment, Hp eradication also improved chronic atrophic gastritis (RR = 1.84, 95% CI: 1.30-2.61, p < 0.01) and intestinal metaplasia (RR = 1.41, 95% CI: 1.15-1.73, p < 0.01). However, in terms of preventing dysplasia progression (RR = 0.86, 95% CI: 0.37-2.00) and improving dysplasia (RR = 0.89, 95% CI: 0.47-1.70), Hp eradication had no advantage compared to placebo or no treatment.

CONCLUSIONS

Hp eradication therapy could prevent the progression of gastric precancerous lesions and reverse them. Notably, intestinal metaplasia can be reversed, but this may only be appropriate for patients with epigenetic alterations and milder lesions.

MAT Gain of Activity Mutation in Helicobacter pylori Is Associated with Resistance to MTAN Transition State Analogues

Helicobacter pylori is found in the gut lining of more than half of the world's population, causes gastric ulcers, and contributes to stomach cancers. Menaquinone synthesis in H. pylori relies on the rare futalosine pathway, where H. pylori 5'-methylthioadenosine nucleosidase (MTAN) is proposed to play an essential role. Transition state analogues of MTAN, including BuT-DADMe-ImmA (BTDIA) and MeT-DADMe-ImmA (MTDIA), exhibit bacteriostatic action against numerous diverse clinical isolates of H. pylori with minimum inhibitory concentrations (MIC's) of <2 ng/mL. Three H. pylori BTDIA-resistant clones were selected under increasing BTDIA pressure. Whole genome sequencing showed no mutations in MTAN. Instead, resistant clones had mutations in metK, methionine adenosyltransferase (MAT), feoA, a regulator of the iron transport system, and flhF, a flagellar synthesis regulator. The mutation in metK causes expression of a MAT with increased catalytic activity, leading to elevated cellular S-adenosylmethionine. Metabolite analysis and the mutations associated with resistance suggest multiple inputs associated with BTDIA resistance. Human gut microbiome exposed to MTDIA revealed no growth inhibition under aerobic or anaerobic conditions. Transition state analogues of H. pylori MTAN have potential as agents for treating H. pylori infection without disruption of the human gut microbiome or inducing resistance in the MTAN target.

Management of H. pylori Induced Peptic ulcer – A Phytotherapeutic Approach

A peptic ulcer is a chronic infectious disease that creates erosion on the epithelial lining of the stomach. It is a commonly encountered problem in the gastrointestinal tract (GI tract). Patients failed multiple regimens due to resistant H. pylori infection. H. pylori show maximum resistance towards Clarithromycin. Due to the consistent increase in resistance there is urgent need for the development of new drugs. Paying much for the antibiotic treatment one should go for the natural treatments with no side effects. Modern treatment of peptic ulcers emphasizes diet with routinely recommend hospitalization of several weeks. Currently, a lot of medications are coming out of natural products. The phytotherapeutic approach for the resistant H.pylori treatment is assessed. The plant produces many secondary metabolic substances which have a lot of beneficial roles in maintaining human health. Administration of plant products would prevent disease and able to eradicate resistant H.pylori. This review includes many phytoproducts having a wide range of antimicrobial activity. Reviewed phytoproducts includes Phytoceutical, Caffeic acid, phenethyl ester, Flavonoid, Capsaicin, Carotenoid, etc are effective treatment against H.pylori. To see their effect on the resistant H.pylori and to manage this resistant bacteria with an application of plant products is the prime concern of this review. The linkage between phytochemical and peptic ulcers will provide a novel framework for the future.

Dynamics of Oxidative Stress in Helicobacter pylori-Positive Patients with Atrophic Body Gastritis and Various Stages of Gastric Cancer

Gastric cancer is a global health problem. The pathogenesis of this disease remains unclear. This study included 198 H. pylori (+) men aged 45 to 60 years old. Group A included 63 practically healthy men, group B included 45 men with severe atrophic body gastritis, group C included 37 men with epithelial gastric cancer stages I-II according to TNM, and group D included 54 men with epithelial gastric cancer stages III-IV according to the TNM scale. The content of malondialdehyde (MDA), diene conjugates (DCs), superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), and glutathione peroxidase (GPO) was detected using an enzyme immunoassay (ELISA) or spectrophotometric methods in the blood plasma. The concentrations of MDA and DC were increased in the patients of group B compared with group A, and in patients of groups C and D compared with groups A and B. The ratio of MDA/SOD and MDA/CAT was decreased in the patients in group D compared with the patients in group C, and was significantly higher compared with group A. The ratios of MDA/GPO and MDA/GST increased linearly and were at a maximum in groups C and D. Our work determined that indicators of oxidative stress may be the biochemical substrate, which brings together the various stages of the Correa cascade, and may explain disease progression. The dynamics of changes in the content of SOD and CAT in the plasma in patients with gastric cancer may be a target of future investigations.

Interactions of 2,6-substituted purines with purine nucleoside phosphorylase from Helicobacter pylori in solution and in the crystal, and the effects of these compounds on cell cultures of this bacterium

Helicobacter pylori represents a global health threat with around 50% of the world population infected. Due to the increasing number of antibiotic-resistant strains, new strategies for eradication of H. pylori are needed. In this study, we suggest purine nucleoside phosphorylase (PNP) as a possible new drug target, by characterising its interactions with 2- and/or 6-substituted purines as well as the effect of these compounds on bacterial growth. Inhibition constants are in the micromolar range, the lowest being that of 6-benzylthio-2-chloropurine. This compound also inhibits H. pylori 26695 growth at the lowest concentration. X-ray structures of the complexes of PNP with the investigated compounds allowed the identification of interactions of inhibitors in the enzyme’s base-binding site and the suggestion of structures that could bind to the enzyme more tightly. Our findings prove the potential of PNP inhibitors in the design of drugs against H. pylori.

Helicobacter pylori: an up-to-date overview on the virulence and pathogenesis mechanisms

Helicobacter pylori is an organism associated with ulcer disease and gastric cancer. The latter is one of the most prevalent malignancies and currently the fourth major cause of cancer-related deaths globally. The pathogen infects about 50% of the world population, and currently, no treatment ensures its total elimination. There has been an increase in our understanding of the pathophysiology and pathogenesis mechanisms of H. pylori over the years. H. pylori can induce several genetic alterations, express numerous virulence factors, and trigger diverse adaptive mechanisms during its adherence and colonization. For successful colonization and infection establishment, several effector proteins/toxins are released by the organism. Evidence is also available reporting spiral to coccoid transition as a unique tactic H. pylori uses to survive in the host's gastrointestinal tract (GIT). Thus, the virulence and pathogenicity of H. pylori are under the control of complex interplay between the virulence factors, host, and environmental factors. Expounding the role of the various virulence factors in H. pylori pathogenesis and clinical outcomes is crucial for vaccine development and in providing and developing a more effective therapeutic intervention. Here we critically reflect on H. pylori infection and delineate what is currently known about the virulence and pathogenesis mechanisms of H. pylori.

Helicobacter species binding to the human gastric mucosa

Helicobacter pylori infects half of the world population, being associated with several gastric disorders, such as chronic gastritis and gastric carcinoma. The Helicobacter genus also includes other gastric helicobacters, such as H. heilmannii¸ H. ailurogastricus, H. suis, H. felis, H. bizzozeronii, and H. salomonis. These gastric helicobacters colonize both the human and animal stomach. The prevalence of gastric non-Helicobacter pylori Helicobacter (NHPH) species in humans has been described as low, and the in vitro binding to the human gastric mucosa was never assessed. Herein, human gastric tissue sections were used for the evaluation of the tissue glycophenotype and for the binding of gastric NHPH strains belonging to different species. Histopathological evaluation showed that 37.5% of the patients enrolled in our cohort presented chronic gastritis, while the presence of neutrophil or eosinophilic activity (chronic active gastritis) was observed in 62.5% of the patients. The secretor phenotype was observed in 68.8% of the individuals, based on the expression of Lewis B antigen and binding of the UleX lectin. The in vitro binding assay showed that all the NHPH strains evaluated were able to bind, albeit in low frequency, to the human gastric mucosa. The H. heilmannii, H. bizzozeronii, and H. salomonis strains displayed the highest binding ability both to the gastric superficial epithelium and to the deep glands. Interestingly, we observed binding of NHPH to the gastric mucosa of individuals with severe chronic inflammation and intestinal metaplasia, suggesting that NHPH binding may not be restricted to the healthy gastric mucosa or slight chronic gastritis. Furthermore, the in vitro binding of NHPH strains was observed both in secretor and non-secretor individuals in a similar frequency. In conclusion, this study is the first report of the in vitro binding ability of gastric NHPH species to the human gastric mucosa. The results suggest that other glycans, besides the Lewis antigens, could be involved in the bacterial adhesion mechanism; however, the molecular intervenients remain unknown.

Helicobacter pylori cagA status and gastric mucosa-associated lymphoid tissue lymphoma: a systematic review and meta-analysis

Background

Recent studies have investigated the role of Helicobacter pylori infection in the development of gastric mucosa-associated lymphoid tissue (MALT) lymphoma. It is estimated that approximately 0.1% of people infected with H. pylori develop gastric MALT lymphoma. However, the role of the CagA antigen, the highest causative agent of H. pylori, in increasing the risk of gastric MALT lymphoma remains unclear and controversial. A systematic review and meta-analysis were conducted to evaluate the effect of cagA status on the development of gastric MALT lymphoma.

Methods

All articles evaluating the status of the cagA gene in the development of gastric MALT lymphoma were collected using systematic searches in online databases, including PubMed, Scopus, Embase, and Google Scholar, regardless of publication date. The association between cagA and gastric MALT lymphoma was assessed using the odds ratio (OR) summary. In addition, a random-effects model was used in cases with significant heterogeneity.

Results

A total of 10 studies met our inclusion criteria, among which 1860 patients participated. No association between cagA status and the development of MALT lymphoma (extranodal marginal zone B-cell lymphoma) was found in this study (OR 1.30; 0.906–1.866 with 95% CIs; I²: 45.83; Q-value: 12.92). Surprisingly, a meaningful association was observed between cagA status and diffuse large B-cell lymphoma (OR 6.43; 2.45–16.84 with 95% CIs). We also observed an inverse association between vacA and gastric MALT lymphoma risk (OR 0.92; 0.57–1.50 with 95% CIs).

Conclusions

It seems that the infection with cagA-positive H. pylori strains does not have a meaningful effect on the gastric MALT lymphoma formation, while translocated CagA antigen into the B cells plays a crucial role in the development of diffuse large B-cell lymphoma.

The role of microbiota in respiratory health and diseases, particularly in tuberculosis

Trillions of beneficial and hostile microorganisms live in the human respiratory and gastrointestinal tracts, which act as gatekeepers in maintaining human health, i.e., protecting the body from pathogens by colonizing mucosal surfaces with microbiota-derived antimicrobial metabolites such as short-chain fatty acids or host-derived cytokines and chemokines. It is widely accepted that the microbiome interacts with each other and with the host in a mutually beneficial relationship. Microbiota in the respiratory tract may also play a crucial role in immune homeostasis, maturation, and maintenance of respiratory physiology. Anti-TB antibiotics may cause dysbiosis in the lung and intestinal microbiota, affecting colonization resistance and making the host more susceptible to Mycobacterium tuberculosis (M. tuberculosis) infection. This review discusses recent advances in our understanding of the lung microbiota composition, the lungs and intestinal microbiota related to respiratory health and diseases, microbiome sequencing and analysis, the bloodstream, and the lymphatic system that underpin the gut-lung axis in M. tuberculosis-infected humans and animals. We also discuss the gut-lung axis interactions with the immune system, the role of the microbiome in TB pathogenesis, and the impact of anti-TB antibiotic therapy on the microbiota in animals, humans, and drug-resistant TB individuals.

Designing and development of epitope-based vaccines against Helicobacter pylori

Helicobacter pylori infection is the principal cause of serious diseases (e.g. gastric cancer and peptic ulcers). Antibiotic therapy is an inadequate strategy in H. pylori eradication because of which vaccination is an inevitable approach. Despite the presence of countless vaccine candidates, current vaccines in clinical trials have performed with poor efficacy which makes vaccination extremely challenging. Remarkable advancements in immunology and pathogenic biology have provided an appropriate opportunity to develop various epitope-based vaccines. The fusion of proper antigens involved in different aspects of H. pylori colonization and pathogenesis as well as peptide linkers and built-in adjuvants results in producing epitope-based vaccines with excellent therapeutic efficacy and negligible adverse effects. Difficulties of the in vitro culture of H. pylori, high genetic variation, and unfavourable immune responses against feeble epitopes in the complete antigen are major drawbacks of current vaccine strategies that epitope-based vaccines may overcome. Besides decreasing the biohazard risk, designing precise formulations, saving time and cost, and induction of maximum immunity with minimum adverse effects are the advantages of epitope-based vaccines. The present article is a comprehensive review of strategies for designing and developing epitope-based vaccines to provide insights into the innovative vaccination against H. pylori.

The preparation of bifunctional hybrid nano-flowers and their application in the enzyme-linked immunosorbent assay for Helicobacter pylori detection

As the infection by Helicobacter pylori (H. pylori, HP) remains for a lifetime and may induce diseases such as gastric cancer, it is vital to detect and diagnose it. A new non-invasive indirect enzyme-linked immunosorbent assay (iELISA) method based on nano-flowers (NFs) is very advantageous for the sensitive detection of HP. Furthermore, the established iELISA method based on the organic-inorganic bifunctional hybrid nano-flowers including rabbit polyclonal antibody of HP labeled with peroxidase from horseradish (R-HP-Ab-HRP@Cu2+ NFs) showed linearity with HP at a concentration of 0-105 CFU mL-1 (R2 = 0.9997). Moreover, the limit of detection (LOD) reached 50 CFU mL-1, and not only was the detection sensitivity 20 times higher than that based on rabbit polyclonal antibody of HP labeled with peroxidase from horseradish (R-HP-Ab-HRP) but also the stability of R-HP-Ab-HRP in NFs was improved. In addition, the OD450 nm value was still linearly related to the concentration of HP at a range of 0-105 CFU mL-1 (R2 = 0.9952) with a LOD of 50 CFU mL-1 in an artificial saliva system. This study provided a sensitive, low-cost and convenient method for the non-invasive detection of HP.

Adhesion of Helicobacter Species to the Human Gastric Mucosa: A Deep Look Into Glycans Role

Helicobacter species infections may be associated with the development of gastric disorders, such as gastritis, peptic ulcers, intestinal metaplasia, dysplasia and gastric carcinoma. Binding of these bacteria to the gastric mucosa occurs through the recognition of specific glycan receptors expressed by the host epithelial cells. This review addresses the state of the art knowledge on these host glycan structures and the bacterial adhesins involved in Helicobacter spp. adhesion to gastric mucosa colonization. Glycans are expressed on every cell surface and they are crucial for several biological processes, including protein folding, cell signaling and recognition, and host-pathogen interactions. Helicobacter pylori is the most predominant gastric Helicobacter species in humans. The adhesion of this bacterium to glycan epitopes present on the gastric epithelial surface is a crucial step for a successful colonization. Major adhesins essential for colonization and infection are the blood-group antigen-binding adhesin (BabA) which mediates the interaction with fucosylated H-type 1 and Lewis B glycans, and the sialic acid-binding adhesin (SabA) which recognizes the sialyl-Lewis A and X glycan antigens. Since not every H. pylori strain expresses functional BabA or SabA adhesins, other bacterial proteins are most probably also involved in this adhesion process, including LabA (LacdiNAc-binding adhesin), which binds to the LacdiNAc motif on MUC5AC mucin. Besides H. pylori, several other gastric non-Helicobacter pylori Helicobacters (NHPH), mainly associated with pigs (H. suis) and pets (H. felis, H. bizzozeronii, H. salomonis, and H. heilmannii), may also colonize the human stomach and cause gastric disease, including gastritis, peptic ulcers and mucosa-associated lymphoid tissue (MALT) lymphoma. These NHPH lack homologous to the major known adhesins involved in colonization of the human stomach. In humans, NHPH infection rate is much lower than in the natural hosts. Differences in the glycosylation profile between gastric human and animal mucins acting as glycan receptors for NHPH-associated adhesins, may be involved. The identification and characterization of the key molecules involved in the adhesion of gastric Helicobacter species to the gastric mucosa is important to understand the colonization and infection strategies displayed by different members of this genus.

Helicobacter pylori: Commensal, symbiont or pathogen?

This review considers the data on Helicobacter pylori (H. pylori), which have been accumulated over 40 years since its description as an etiological factor in gastrointestinal diseases. The majority of modern publications are devoted to the study of the pathogenic properties of the microorganism in the development of chronic gastritis, peptic ulcer disease, and gastric cancer, as well as methods for its eradication. However, in recent years, there have been more and more studies which have suggested that H. pylori has a beneficial, or potentially positive, effect on the human body. The authors have attempted to objectively analyze the information accumulated in the literature on H. pylori. Some studies consider it as one of the recently identified human bacterial pathogens, and special attention is paid to the evidence suggesting that it is probably part of the composition of the human microbiome as a commensal (commensal from French to English is a table companion) or even a symbiont. The presented data discussing the presence or absence of the effect of H. pylori on human health suggest that there is an apparent ambiguity of the problem. The re-assessment of the data available on H. pylori infection is important in order to answer the question of whether it is necessary to create a program of mass H. pylori eradication or to apply a more personalized approach to treating patients with H. pylori-associated gastrointestinal diseases and to perform eradication therapy.

Helicobacter pylori treatment in the post-antibiotics era-searching for new drug targets

Abstract

Helicobacter pylori, a member of Epsilonproteobacteria, is a Gram-negative microaerophilic bacterium that colonizes gastric mucosa of about 50% of the human population. Although most infections caused by H. pylori are asymptomatic, the microorganism is strongly associated with serious diseases of the upper gastrointestinal tract such as chronic gastritis, peptic ulcer, duodenal ulcer, and gastric cancer, and it is classified as a group I carcinogen. The prevalence of H. pylori infections varies worldwide. The H. pylori genotype, host gene polymorphisms, and environmental factors determine the type of induced disease. Currently, the most common therapy to treat H. pylori is the first line clarithromycin–based triple therapy or a quadruple therapy replacing clarithromycin with new antibiotics. Despite the enormous recent effort to introduce new therapeutic regimens to combat this pathogen, treatment for H. pylori still fails in more than 20% of patients, mainly due to the increased prevalence of antibiotic resistant strains. In this review we present recent progress aimed at designing new anti-H. pylori strategies to combat this pathogen. Some novel therapeutic regimens will potentially be used as an extra constituent of antibiotic therapy, and others may replace current antibiotic treatments.

Key points

• Attempts to improve eradication rate of H. pylori infection.

• Searching for new drug targets in anti-Helicobacter therapies.

Gastroenterological complications in kidney transplant patients

Kidney transplantation is the surgical operation by which one of the two original kidneys is replaced with another healthy one donated by a compatible individual. In most cases, donors are recently deceased. There is the possibility of withdrawing a kidney from a consenting living subject. Usually, living donors are direct family members, but they could be volunteers completely unrelated to the recipient. A much-feared complication in case of kidney transplantation is the appearance of infections. These tend to arise due to immune-suppressor drugs administered as anti-rejection therapy. In this review, we describe the gastrointestinal complications that can occur in subjects undergoing renal transplantation associated with secondary pathogenic microorganisms or due to mechanical injury during surgery or to metabolic or organic toxicity correlated to anti-rejection therapy. Some of these complications may compromise the quality of life or pose a significant risk of mortality; fortunately, many of them can be prevented and treated without the stopping the immunosuppression, thus avoiding the patient being exposed to the risk of rejection episodes.

Effects of eradicating Helicobacter pylori on metachronous gastric cancer prevention: A systematic review and meta-analysis

BACKGROUND

Helicobacter pylori (H pylori) infection is closely associated with the incidence of gastric cancer. However, whether H pylori eradication prevents metachronous gastric cancer remains uncertain. The aim of our study is to assess how eradicating H pylori influences metachronous gastric cancer onset following treatment of early stage gastric cancer via endoscopic resective surgery.

PATIENTS AND METHODS

We performed a systematic review and meta-analysis by searching PubMed, Embase, Web of Science, and the Cochrane Library. Cohort studies and randomized controlled trials that compared individuals receiving H pylori eradication with individuals receiving placebo/nontreatment and evaluated the subsequent onset of metachronous gastric cancer as the main outcome were eligible for our study. Two authors reviewed articles and extracted data independently. Integrated results for all data were presented as risk ratio.

RESULTS

Thirteen studies containing 3863 patients were consistent with study inclusion criteria. Of the 2480 individuals in whom H pylori was successfully eradicated, 163 (6.57%) developed metachronous gastric cancer, as compared with 176 (12.73%) out of 1383 persistently infected individuals. The pooled risk ratio of metachronous gastric cancer for these studies was 0.46 (95% CI, 0.37-0.57, P < .001), providing support for the therapeutic elimination of H pylori. Subgroup analyses yielded similar results.

CONCLUSION

Eradicating H pylori via therapeutic treatment can effectively reduce rates of metachronous gastric cancer, and as such, it should be implemented in H pylori-infected individuals recently treated for early stage gastric cancers via endoscopic resection.

Adherent-invasive Escherichia coli (AIEC): Cause or consequence of inflammation, dysbiosis, and rupture of cellular joints in patients with IBD?

There are many factors contributing to the development of gastrointestinal diseases, grouped into genetic, environmental, and lifestyle factors. In recent years attention has fallen on pathogens; in particular, Bacteroides fragilis, Fusobacterium nucleatum, Escherichia coli (E. coli) and Helicobacter pylori have been studied. Several points remain to be clarified, and above all, as regards the adherent-invasive E. coli strains of E. coli, one wonders if they are a cause or a consequence of the disease. In this review, we have tried to clarify some points by examining a series of recent publications regarding the involvement of the bacterium in the pathology, even if other studies are necessary.

Probiotic effect on Helicobacter pylori attachment and inhibition of inflammation in human gastric epithelial cells

Helicobacter pylori (H. pylori) is a major cause of chronic gastritis, gastric ulcers and gastric cancer. Recent studies have identified that probiotics are beneficial to human health due, in part, to their anti-H. pylori activities. Therefore, the present study investigated the antagonistic and local immunoregulatory activities of seven commercial probiotic strains and explored their mechanisms of actions. The human gastric epithelial cell line-1 (GES-1) was used to assess the effects of probiotics on the adhesion ability of H. pylori. GES-1 cells were infected with H. pylori plus lipopolysaccharide (HP-LPS) or the drug-resistant H. pylori strain (HP021) in the presence or absence of live probiotics. Following this, the growth rate and the adhesion ability of GES-1 cells were detected using MTT and urease activity assay. Toll-like receptor 4 (TLR4), NFKB inhibitor-α (IκBα) and nuclear factor (NF)-κB levels were measured by western blot analysis. The amount of interleukin (IL)-8 in the cell culture medium was determined by ELISA. Amongst the seven probiotic strains studied, live Lactobacillus acidophilus (L. acidophilus) and Lactobacillus bulgaricus (L. bulgaricus) inhibited H. pylori adherence to GES-1 cells most significantly. L. bulgaricus inhibited IL-8 production by GES-1 cells through modulation of the TLR4/IκBα/NF-κB pathway. Therefore, the present results suggested that consumption of food containing L. acidophilus and L. bulgaricus may be used as an adjuvant therapy for H. pylori-associated gastritis.

Exploring the microbiota to better understand gastrointestinal cancers physiology

Gastrointestinal cancers account for around 40% of cancer-related deaths worldwide, representing a global health burden. There is a growing body of evidence highlighting the link between microbiota and gastrointestinal tumorigenesis and/or resistance to therapy. In the present manuscript, we reviewed the published studies on the relationship between the microbiota and the different gastrointestinal tumors, namely, gastric, colorectal and esophageal, including also the cancer of accessory organs such as liver and pancreas. There is an emergent interest in the manipulation of gastrointestinal microflora in order to understand the gastrointestinal tumorigenesis' processes and the establishment of chemoresistance mechanisms.

In silico proteomic and phylogenetic analysis of the outer membrane protein repertoire of gastric Helicobacter species

Helicobacter (H.) pylori is an important risk factor for gastric malignancies worldwide. Its outer membrane proteome takes an important role in colonization of the human gastric mucosa. However, in zoonotic non-H. pylori helicobacters (NHPHs) also associated with human gastric disease, the composition of the outer membrane (OM) proteome and its relative contribution to disease remain largely unknown. By means of a comprehensive survey of the diversity and distribution of predicted outer membrane proteins (OMPs) identified in all known gastric Helicobacter species with fully annotated genome sequences, we found genus- and species-specific families known or thought to be implicated in virulence. Hop adhesins, part of the Helicobacter-specific family 13 (Hop, Hor and Hom) were restricted to the gastric species H. pylori, H. cetorum and H. acinonychis. Hof proteins (family 33) were putative adhesins with predicted Occ- or MOMP-family like 18-stranded β-barrels. They were found to be widespread amongst all gastric Helicobacter species only sporadically detected in enterohepatic Helicobacter species. These latter are other members within the genus Helicobacter, although ecologically and genetically distinct. LpxR, a lipopolysaccharide remodeling factor, was also detected in all gastric Helicobacter species but lacking as well from the enterohepatic species H. cinaedi, H. equorum and H. hepaticus. In conclusion, our systemic survey of Helicobacter OMPs points to species and infection-site specific members that are interesting candidates for future virulence and colonization studies.

Pathogenicity-island-encoded regulatory RNAs regulate bacterial virulence and pathogenesis

Bacterial regulatory RNAs (regRNAs) have been widely studied for decades and shown to be involved in various aspects of bacterial survival, including their virulence and pathogenesis. Recently, many regRNAs have been found to be encoded within bacterial pathogenicity islands (PAIs). These PAI-encoded regRNAs also play important regulatory roles in bacterial virulence and pathogenesis. In this review, we introduce the reported PAI-encoded regRNAs individually, focusing on their types, target genes, regulatory roles, regulatory mechanisms and significance. We also summarize the virulence and pathogenesis of the pathogens concerned.

Genome-wide mRNA-miRNA profiling uncovers a role of the microRNA miR-29b-1-5p/PHLPP1 signalling pathway in Helicobacter pylori-driven matrix metalloproteinase production in gastric epithelial cells

Aberrant expression of microRNAs (miRNAs) is associated with tumour progression, extracellular matrix remodelling, and cell proliferation. miRNAs modulate host gene expression during infection by pathogens such as Helicobacter pylori, which is associated with varying degrees of gastric pathology. In order to gain insight into the regulation of gene expression by miRNAs during H. pylori infection of gastric epithelial cells and its likely downstream consequences, we analysed the transcriptomes and miRnomes of AGS cells infected with H. pylori. In silico analysis of miRNA-mRNA interactions suggested that miR-29b-1-5p was a likely regulator of pathways associated with gastric epithelial cell pathology. We validated PH domain leucine rich phosphatase 1 (PHLPP1), a negative regulator of the Akt signalling pathway, as a target of miR-29b-1-5p. In an in vivo mouse model, we observed that infection with H. pylori was associated with upregulation of miR-29b-1-5p and downregulation of PHLPP1. Transfection with either a mimic or an inhibitor of miR-29b-1-5p confirmed that downregulation of PHLPP1 upregulates Akt-dependent NF-κB signalling leading to activation of matrix metalloproteinases 2 and 9, players in the degradation of extracellular matrix during H. pylori infection. The secreted antigen HP0175 was associated with upregulation of miR-29b-1-5p, regulation of metalloproteinase activity, and migration of AGS cells. Our study suggests that targeting the miR-29b-1-5p/PHLPP1 signalling axis could be a potential host-directed approach for regulating the outcome of H. pylori infection.

GIT2-A keystone in ageing and age-related disease

Since its discovery, G protein-coupled receptor kinase-interacting protein 2, GIT2, and its family member, GIT1, have received considerable interest concerning their potential key roles in regulating multiple inter-connected physiological and pathophysiological processes. GIT2 was first identified as a multifunctional protein that is recruited to G protein-coupled receptors (GPCRs) during the process of receptor internalization. Recent findings have demonstrated that perhaps one of the most important effects of GIT2 in physiology concerns its role in controlling multiple aspects of the complex ageing process. Ageing can be considered the most prevalent pathophysiological condition in humans, affecting all tissue systems and acting as a driving force for many common and intractable disorders. The ageing process involves a complex interplay among various deleterious activities that profoundly disrupt the body's ability to cope with damage, thus increasing susceptibility to pathophysiologies such as neurodegeneration, central obesity, osteoporosis, type 2 diabetes mellitus and atherosclerosis. The biological systems that control ageing appear to function as a series of interconnected complex networks. The inter-communication among multiple lower-complexity signaling systems within the global ageing networks is likely coordinated internally by keystones or hubs, which regulate responses to dynamic molecular events through protein-protein interactions with multiple distinct partners. Multiple lines of research have suggested that GIT2 may act as one of these network coordinators in the ageing process. Identifying and targeting keystones, such as GIT2, is thus an important approach in our understanding of, and eventual ability to, medically ameliorate or interdict age-related progressive cellular and tissue damage.

The multifaceted link between inflammation and human diseases

Increasing reports on epidemiological, diagnostic, and clinical studies suggest that dysfunction of the inflammatory reaction results in chronic illnesses such as cancer, arthritis, arteriosclerosis, neurological disorders, liver diseases, and renal disorders. Chronic inflammation might progress if injurious agent persists; however, more typically than not, the response is chronic from the start. Distinct to most changes in acute inflammation, chronic inflammation is characterized by the infiltration of damaged tissue by mononuclear cells like macrophages, lymphocytes, and plasma cells, in addition to tissue destruction and attempts to repair. Phagocytes are the key players in the chronic inflammatory response. However, the important drawback is the activation of pathological phagocytes, which might result from continued tissue damage and lead to harmful diseases. The longer the inflammation persists, the greater the chance for the establishment of human diseases. The aim of this review was to focus on advances in the understanding of chronic inflammation and to summarize the impact and involvement of inflammatory agents in certain human diseases.

Changes in the indices of prooxidant and antioxidant systems in blood plasma in men with atrophic gastritis and gastric cancer

AIM

To study changes in the indices of prooxidant and antioxidant systems in plasma in men with atrophic gastritis and gastric cancer.

MATERIALS AND METHODS

The study included 60 healthy men, 42 patients with atrophic gastritis and 50 men, nicardipine patients with gastric cancer stage II according to TNM. All patients underwent serological diagnosis of diffuse atrophic gastritis (definition of pepsinogens and gas- trin-17) and Helicobacter pylori infection. The diagnosis of &quot;atrophic gastritis&quot; was verified by morphological examination of biopsy speci- mens obtained during fibroesophagogastroduodenoscopy. Diagnosis of gastric cancer was carried out in the Krasnoyarsk regional oncologic dispensary on the basis of a comprehensive instrumental and morphological examination. All patients spectrophotometric methods in plasma was determined the content of diene conjugates (DC), malonic dialdehyde (MDA), glutathione-S-transferase (GST), glutathione peroxidase (GPO), superoxide dismutase (SOD) and catalase.

RESULTS

The concentration of SOD, GST, GPO and catalase had no significant differences in patients with atrophic gastritis and gastric cancer and prevailed in comparison with healthy persons. Patients with cancer of the stomach content in the blood plasma DK 2.7 times and MDA at 35.2 times higher than healthy individuals, indicating severe oxidative stress in patients with cancer. In patients with atrophic gastritis was ob- served similar but less pronounced pattern.

CONCLUSION

The results indicate the presence of oxidative stress in men with atrophic gastritis and gastric cancer.

T cell subsets play an important role in the determination of the clinical outcome of Helicobacter pylori infection

Helicobacter pylori (H. pylori) is one of the most prevalent human pathogen and a persistent infection with this bacterium causes common pathologies, such as gastritis or peptic ulcers, and also less common but more serious pathologies, such as gastric cancer or gastric mucosa-associated lymphoid tissue (MALT) lymphoma. The clinical outcome of gastrointestinal infection sustained by H. pylori is determined by the reciprocal interactions between virulence factors of the bacterium and host factors, including immune response genes. Although H. pylori induces a strong immune response, the bacterium is not eliminated. The eradication failure could be attributed to the bacterial capability to regulate helper T (Th) cell-related responses. H. pylori specific CD4⁺ T cells play a fundamental role in regulating host immunity and immunopathologic events. It has been documented that Th1, Th2, Th9, Th17, Th22 and T regulatory (Treg) cells, separately or in coordination with each other, can affect the outcome of the infection sustained by of H. pylori. Some studies indicated that both Th1 and Th17 cells may be protective or pathogenic, whereas Treg and Th2 cells perform anti-inflammatory impacts during H. pylori infection. This review gathers recent information regarding the association of the CD4⁺ T cells-mediated immunological responses and the clinical consequence of H. pylori infection.

Gastric Cancer as Preventable Disease

Gastric cancer, 1 of the 5 most common causes of cancer death, is associated with a 5-year overall survival rate less than 30%. A minority of cancers occurs as part of syndromic diseases; more than 90% of adenocarcinomas are considered as the ultimate consequence of a longstanding mucosal inflammation. Helicobacter pylori infection is the leading etiology of non-self-limiting gastritis, which may result in atrophy of the gastric mucosa and impaired acid secretion. Gastric atrophy establishes a field of cancerization prone to further molecular and phenotypic changes, possibly resulting in cancer growth. This well-understood natural history provides the clinicopathologic rationale for primary and secondary cancer prevention strategies. A large body of evidence demonstrates that combined primary (H pylori eradication) and secondary (mainly endoscopy) prevention efforts may prevent or limit the progression of gastric oncogenesis. This approach, which is tailored to different country-specific gastric cancer incidence, socioeconomic, and cultural factors, requires that the complementary competences of gastroenterologists, oncologists, and pathologists be amalgamated into a common strategy of health policy.

Molecular Mechanisms of Natural Honey Against H. pylori Infection Via Suppression of NF-κB and AP-1 Activation in Gastric Epithelial Cells

BACKGROUND AND AIMS

Natural honey has been used as a medicine since ancient times. Honey is widely known for its antibacterial properties against H. pylori; however, the mechanisms of its antibacterial activity are not fully known. The present study was performed to examine the molecular mechanisms by which natural honey can inhibit H. pylori infection in gastric epithelial cells.

METHODS

Electrophoretic mobility shift assay was used to measure NF-κB- and AP-1-DNA binding activity. Western blotting was used to detect IκB-α and COX-2 expression.

RESULTS

H. pylori induced NF-κB and AP-1 DNA-binding activity in gastric epithelial cells. Manuka honey inhibited H. pylori-induced NF-κB and AP-1 in a time- and dose-dependent manner. Maximum inhibition of H. pylori-induced NF-κB and AP-1 by manuka honey was observed at concentrations of 20% at 1-2 h. Pre-treatment of AGS cells with other commercial natural honeys also inhibited H. pylori-induced NF-κB and AP-1 DNA-binding activity. Honey prevented H. pylori-induced degradation of IκB-α protein and downregulated COX-2 protein levels.

CONCLUSIONS

Our findings suggest that natural honey exerts its inhibitory effects against H. pylori by inhibiting NF-κB and AP-1 activation and downregulation of COX-2 expression. These results provide new mechanistic insights into honey effects in the suppression of H. pylori infection.

Toll-like receptor 2: An important immunomodulatory molecule during Helicobacter pylori infection

Toll like receptors (TLRs) are an essential subset of pathogen recognition receptors (PRRs) which identify the microbial components and contribute in the regulation of innate and adaptive immune responses against the infectious agents. The TLRs, especially TLR2, TLR4, TLR5 and TLR9, participate in the induction of immune response against H. pylori. TLR2 is expressed on a number of immune and non-immune cells and recognizes a vast broad of microbial components due to its potential to form heterodimers with other TLRs, including TLR1, TLR6 and TLR10. A number of H. pylori-related molecules may contribute to TLR2-dependent responses, including HP-LPS, HP-HSP60 and HP-NAP. TLR2 plays a pivotal role in regulation of immune response to H. pylori through activation of NF-κB and induction of cytokine expression in epithelial cells, monocytes/macrophages, dendritic cells, neutrophils and B cells. The TLR2-related immune response that is induced by H. pylori-derived components may play an important role regarding the outcome of the infection toward bacterial elimination, persistence or pathological reactions. The immunomodulatory and immunoregulatory roles of TLR2 during H. pylori infection were considered in this review. TLR2 could be considered as an interesting therapeutic target for treatment of H. pylori-related diseases.

Sequence Analysis of Hypothetical Proteins from Helicobacter pylori 26695 to Identify Potential Virulence Factors

Helicobacter pylori is a Gram-negative bacteria that is responsible for gastritis in human. Its spiral flagellated body helps in locomotion and colonization in the host environment. It is capable of living in the highly acidic environment of the stomach with the help of acid adaptive genes. The genome of H. pylori 26695 strain contains 1,555 coding genes that encode 1,445 proteins. Out of these, 340 proteins are characterized as hypothetical proteins (HP). This study involves extensive analysis of the HPs using an established pipeline which comprises various bioinformatics tools and databases to find out probable functions of the HPs and identification of virulence factors. After extensive analysis of all the 340 HPs, we found that 104 HPs are showing characteristic similarities with the proteins with known functions. Thus, on the basis of such similarities, we assigned probable functions to 104 HPs with high confidence and precision. All the predicted HPs contain representative members of diverse functional classes of proteins such as enzymes, transporters, binding proteins, regulatory proteins, proteins involved in cellular processes and other proteins with miscellaneous functions. Therefore, we classified 104 HPs into aforementioned functional groups. During the virulence factors analysis of the HPs, we found 11 HPs are showing significant virulence. The identification of virulence proteins with the help their predicted functions may pave the way for drug target estimation and development of effective drug to counter the activity of that protein.

Stomach development, stem cells and disease

The stomach, an organ derived from foregut endoderm, secretes acid and enzymes and plays a key role in digestion. During development, mesenchymal-epithelial interactions drive stomach specification, patterning, differentiation and growth through selected signaling pathways and transcription factors. After birth, the gastric epithelium is maintained by the activity of stem cells. Developmental signals are aberrantly activated and stem cell functions are disrupted in gastric cancer and other disorders. Therefore, a better understanding of stomach development and stem cells can inform approaches to treating these conditions. This Review highlights the molecular mechanisms of stomach development and discusses recent findings regarding stomach stem cells and organoid cultures, and their roles in investigating disease mechanisms.

Role of Helicobacter pylori infection in generation of gastric cancer stem cells

Helicobacter pylori (H. pylori) is a key cause of gastric cancer, and gastric cancer stem cells play an important role in the development of gastric cancer. Therefore in this paper, we try to explore the relationship between H. pylori infection and stem cells in gastric cancer. H. pylori infection promotes the generation of gastric cancer stem cells through the epithelial-mesenchymal transition (EMT). In addition, H. pylori participates in the processes of the formation and progression of gastric cancer stem cells by affecting related signal pathways, such as Wnt/β-catenin, Hh/SHH, Notch, FGF/BMP. On this basis, we disscuss the challenges and future directions in the research of H. pylori infection and gastric cancer stem cells.

Fragmentation of CagA Reduces Hummingbird Phenotype Induction by Helicobactor pylori

Infection with Helicobacter pylori (H. pylori) has been linked to various gastro-intestinal diseases; nevertheless it remains to be clarified why only a minority of infected individuals develop illness. Studies from the West have indicated that the cagA gene and the associated EPIYA genotype of H. pylori is closely linked to the development of severe gastritis and gastric carcinoma; however, as yet no consistent correlation has been found among the bacteria from East Asia. In addition to genotype variation, the CagA protein undergoes fragmentation; however, the functional significance of fragmentation with respect to H. pylori infection remains unknown. In this study, we isolated 594 H. pylori colonies from 99 patients and examined the fragmentation patterns of CagA protein using immunoblotting. By analyzing the ability of the isolates to induce the host cell morphological transition to the highly invasive hummingbird phenotype, we demonstrated that H. pylori colonies with substantial CagA fragmentation are less potent in terms of causing this morphological transition. Our results uncovered a functional role for CagA fragmentation with respect to H. pylori-induced hummingbird phenotype formation and these findings suggest the possibility that the post-translational processing of CagA may be involved in H. pylori infection pathogenesis.

IL-17a and IL-22 Induce Expression of Antimicrobials in Gastrointestinal Epithelial Cells and May Contribute to Epithelial Cell Defense against Helicobacter pylori

Helicobacter pylori colonization of the human stomach can lead to adverse clinical outcomes including gastritis, peptic ulcers, or gastric cancer. Current data suggest that in addition to bacterial virulence factors, the magnitude and types of immune responses influence the outcome of colonization. Specifically, CD4+ T cell responses impact the pathology elicited in response to H. pylori. Because gastritis is believed to be the initiating host response to more detrimental pathological outcomes, there has been a significant interest in pro-inflammatory T cell cytokines, including the cytokines produced by T helper 17 cells. Th17 cells produce IL-17A, IL-17F, IL-21 and IL-22. While these cytokines have been linked to inflammation, IL-17A and IL-22 are also associated with anti-microbial responses and control of bacterial colonization. The goal of this research was to determine the role of IL-22 in activation of antimicrobial responses in models of H. pylori infection using human gastric epithelial cell lines and the mouse model of H. pylori infection. Our data indicate that IL-17A and IL-22 work synergistically to induce antimicrobials and chemokines such as IL-8, components of calprotectin (CP), lipocalin (LCN) and some β-defensins in both human and primary mouse gastric epithelial cells (GEC) and gastroids. Moreover, IL-22 and IL-17A-activated GECs were capable of inhibiting growth of H. pylori in vitro. While antimicrobials were activated by IL-17A and IL-22 in vitro, using a mouse model of H. pylori infection, the data herein indicate that IL-22 deficiency alone does not render mice more susceptible to infection, change their antimicrobial gene transcription, or significantly change their inflammatory response.

New Antibiotic Candidates against Helicobacter pylori

Helicobacter pylori is a Gram-negative bacterium that colonizes the gut of over 50% of the world's population. It is responsible for most peptic ulcers and is an important risk factor for gastric cancer. Antibiotic treatment for H. pylori infections is challenging as drug resistance has developed to antibiotics with traditional mechanisms of action. H. pylori uses an unusual pathway for menaquinone biosynthesis with 5'-methylthioadenosine/S-adenosylhomocysteine nucleosidase (MTAN) catalyzing an essential step. We validated MTAN as a target with a transition-state analogue of the enzyme [Wang, S.; Haapalainen, A. M.; Yan, F.; et al. Biochemistry 2012, 51, 6892-6894]. MTAN inhibitors will only be useful drug candidates if they can both include tight binding to the MTAN target and have the ability to penetrate the complex cell membrane found in Gram-negative H. pylori. Here we explore structural scaffolds for MTAN inhibition and for growth inhibition of cultured H. pylori. Sixteen analogues reported here are transition-state analogues of H. pylori MTAN with dissociation constants of 50 pM or below. Ten of these prevent growth of the H. pylori with IC90 values below 0.01 μg/mL. These remarkable compounds meet the criteria for potent inhibition and cell penetration. As a consequence, 10 new H. pylori antibiotic candidates are identified, all of which prevent H. pylori growth at concentrations 16-2000-fold lower than the five antibiotics, amoxicillin, metronidazole, levofloxacin, tetracyclin, and clarithromycin, commonly used to treat H. pylori infections. X-ray crystal structures of MTAN cocrystallized with several inhibitors show them to bind in the active site making interactions consistent with transition-state analogues.

New and Unexpected Biological Functions for the Src-Homology 2 Domain-Containing Phosphatase SHP-2 in the Gastrointestinal Tract

SHP-2 is a tyrosine phosphatase expressed in most embryonic and adult tissues. SHP-2 regulates many cellular functions including growth, differentiation, migration, and survival. Genetic and biochemical evidence show that SHP-2 is required for rat sarcoma viral oncogene/extracellular signal-regulated kinases mitogen-activated protein kinase pathway activation by most tyrosine kinase receptors, as well as by G-protein-coupled and cytokine receptors. In addition, SHP-2 can regulate the Janus kinase/signal transducers and activators of transcription, nuclear factor-κB, phosphatidyl-inositol 3-kinase/Akt, RhoA, Hippo, and Wnt/β-catenin signaling pathways. Emerging evidence has shown that SHP-2 dysfunction represents a key factor in the pathogenesis of gastrointestinal diseases, in particular in chronic inflammation and cancer. Variations within the gene locus encoding SHP-2 have been associated with increased susceptibility to develop ulcerative colitis and gastric atrophy. Furthermore, mice with conditional deletion of SHP-2 in intestinal epithelial cells rapidly develop severe colitis. Similarly, hepatocyte-specific deletion of SHP-2 induces hepatic inflammation, resulting in regenerative hyperplasia and development of tumors in aged mice. However, the SHP-2 gene initially was suggested to be a proto-oncogene because activating mutations of this gene were found in pediatric leukemias and certain forms of liver and colon cancers. Moreover, SHP-2 expression is up-regulated in gastric and hepatocellular cancers. Notably, SHP-2 functions downstream of cytotoxin-associated antigen A (CagA), the major virulence factor of Helicobacter pylori, and is associated with increased risks of gastric cancer. Further compounding this complexity, most recent findings suggest that SHP-2 also coordinates carbohydrate, lipid, and bile acid synthesis in the liver and pancreas. This review aims to summarize current knowledge and recent data regarding the biological functions of SHP-2 in the gastrointestinal tract.

Pathogenesis of Myeloproliferative Neoplasms: Role and Mechanisms of Chronic Inflammation

Myeloproliferative neoplasms (MPNs) are a heterogeneous group of clonal diseases characterized by the excessive and chronic production of mature cells from one or several of the myeloid lineages. Recent advances in the biology of MPNs have greatly facilitated their molecular diagnosis since most patients present with mutation(s) in the JAK2, MPL, or CALR genes. Yet the roles played by these mutations in the pathogenesis and main complications of the different subtypes of MPNs are not fully elucidated. Importantly, chronic inflammation has long been associated with MPN disease and some of the symptoms and complications can be linked to inflammation. Moreover, the JAK inhibitor clinical trials showed that the reduction of symptoms linked to inflammation was beneficial to patients even in the absence of significant decrease in the JAK2-V617F mutant load. These observations suggested that part of the inflammation observed in patients with JAK2-mutated MPNs may not be the consequence of JAK2 mutation. The aim of this paper is to review the different aspects of inflammation in MPNs, the molecular mechanisms involved, the role of specific genetic defects, and the evidence that increased production of certain cytokines depends or not on MPN-associated mutations, and to discuss possible nongenetic causes of inflammation.

Diversity of the Epsilonproteobacteria Dsb (disulfide bond) systems

The bacterial proteins of the Dsb family-important components of the post-translational protein modification system-catalyze the formation of disulfide bridges, a process that is crucial for protein structure stabilization and activity. Dsb systems play an essential role in the assembly of many virulence factors. Recent rapid advances in global analysis of bacteria have thrown light on the enormous diversity among bacterial Dsb systems. While the Escherichia coli disulfide bond-forming system is quite well understood, the mechanisms of action of Dsb systems in other bacteria, including members of class Epsilonproteobacteria that contain pathogenic and non-pathogenic bacteria colonizing extremely diverse ecological niches, are poorly characterized. Here we present a review of current knowledge on Epsilonproteobacteria Dsb systems. We have focused on the Dsb systems of Campylobacter spp. and Helicobacter spp. because our knowledge about Dsb proteins of Wolinella and Arcobacter spp. is still scarce and comes mainly from bioinformatic studies. Helicobacter pylori is a common human pathogen that colonizes the gastric epithelium of humans with severe consequences. Campylobacter spp. is a leading cause of zoonotic enteric bacterial infections in most developed and developing nations. We focus on various aspects of the diversity of the Dsb systems and their influence on pathogenicity, particularly because Dsb proteins are considered as potential targets for a new class of anti-virulence drugs to treat human infections by Campylobacter or Helicobacter spp.

Inflammation and cancer: till death tears them apart

Advances in biotechnology have enabled the collection of an immeasurable amount of information from genomic, transcriptomic, metabolomic and proteomic studies of tumours within their microenvironments. The dissection of cytokine and chemokine networks has provided new clues to the interactions between cancer cells and their surrounding inflammatory landscape. To bridge the gap between chronic inflammation and cancer, dynamic participants in the tumour microenvironment have been identified, including tumour-associated macrophages (TAMs) and regulatory T cells (Tregs). Both of these cell types are notable for their ability to cause immunosuppressive conditions and support the evasion of tumour immune surveillance. It is clear now that the tumour-promoting inflammatory environment has to be included as one of the major cancer hallmarks. This review explores the recent advances in the understanding of cancer-related inflammation and how this is being applied to comparative oncology studies in humans and domestic species, such as the dog.