HowHelicobacter pylorisenses, targets and interacts with the gastric epithelium

Overcoming antibiotic resistance caused by genetic mutations of Helicobacter pylori with mucin adhesive polymer-based therapeutics

Herein, we describe the 3'-sialyllactose-polyethyleneimine-chlorine e6 conjugate (3PC), meticulously engineered to effectively target Helicobacter bacteria (H. pylori) within the gastric environment. The composition of 3PC comprises polyethyleneimine, a cationic polymer, 3'-sialyllactose, which exhibits a specific binding affinity for H. pylori surface proteins, and a photosensitizer capable of generating oxygen radicals in response to specific wavelengths. The distinctive feature of 3PC lies in its capacity to enhance interaction with the anionic mucus layer facilitated by electrostatic forces. This interaction results in prolonged residence within the intestinal environment. The extended vacation in the intestinal milieu overcomes inherent limitations that have historically impeded conventional antibiotics from efficiently reaching and targeting H. pylori. 3PC can be harnessed as a potent tool for antibacterial photodynamic therapy, and its versatility extends to addressing the challenges posed by various antibiotic-resistant strains. The exceptional efficacy of 3PC in enhancing intestinal residence time and eradicating H. pylori has been robustly substantiated in animal models, particularly in mice. In summary, 3PC is a formidable agent capable of eradicating H. pylori, irrespective of its antibiotic resistance status, by efficiently penetrating and selectively targeting the mucus layer within the gastric environment.

Molecular insights into the fine-tuning of pH-dependent ArsR-mediated regulation of the SabA adhesin in Helicobacter pylori

Adaptation to variations in pH is crucial for the ability of Helicobacter pylori to persist in the human stomach. The acid responsive two-component system ArsRS, constitutes the global regulon that responds to acidic conditions, but molecular details of how transcription is affected by the ArsR response regulator remains poorly understood. Using a combination of DNA-binding studies, in vitro transcription assays, and H. pylori mutants, we demonstrate that phosphorylated ArsR (ArsR-P) forms an active protein complex that binds DNA with high specificity in order to affect transcription. Our data showed that DNA topology is key for DNA binding. We found that AT-rich DNA sequences direct ArsR-P to specific sites and that DNA-bending proteins are important for the effect of ArsR-P on transcription regulation. The repression of sabA transcription is mediated by ArsR-P with the support of Hup and is affected by simple sequence repeats located upstream of the sabA promoter. Here stochastic events clearly contribute to the fine-tuning of pH-dependent gene regulation. Our results reveal important molecular aspects for how ArsR-P acts to repress transcription in response to acidic conditions. Such transcriptional control likely mediates shifts in bacterial positioning in the gastric mucus layer.

Helicobacter pylori cheV1 mutants recover semisolid agar migration due to loss of a previously uncharacterized Type IV filament membrane alignment complex homolog

The bacterial chemotaxis system is a well-understood signaling pathway that promotes bacterial success. Chemotaxis systems comprise chemoreceptors and the CheA kinase, linked by CheW or CheV scaffold proteins. Scaffold proteins provide connections between chemoreceptors and CheA and also between chemoreceptors to create macromolecular arrays. Chemotaxis is required for host colonization by many microbes, including the stomach pathogen Helicobacter pylori. This bacterium builds chemoreceptor-CheA contacts with two distinct scaffold proteins, CheW and CheV1. H. pylori cheW or cheV1 deletion mutants both lose chemoreceptor array formation, but show differing semisolid agar chemotaxis assay behaviors: ∆cheW mutants exhibit total migration failure, whereas ∆cheV1::cat mutants display a 50% reduction. On investigating these varied responses, we found that both mutants initially struggle with migration. However, over time, ∆cheV1::cat mutants develop a stable, enhanced migration capability, termed "migration-able" (Mig+). Whole-genome sequencing analysis of four distinct ∆cheV1::cat Mig+ strains identified single-nucleotide polymorphisms (SNPs) in hpg27_252 (hp0273) that were predicted to truncate the encoded protein. Computational analysis of the hpg27_252-encoded protein revealed it encoded a hypothetical protein that was a remote homolog of the PilO Type IV filament membrane alignment complex protein. Although H. pylori lacks Type IV filaments, our analysis showed it retains an operon of genes for homologs of PilO, PilN, and PilM. Deleting hpg27_252 in the ∆cheV1::cat or wild type strain resulted in enhanced migration in semisolid agar. Our study thus reveals that while cheV1 mutants initially have significant migration defects, they can recover the migration ability through genetic suppressors, highlighting a complex regulatory mechanism in bacterial migration.

IMPORTANCE

Chemotactic motility, present in over half of bacteria, depends on chemotaxis signaling systems comprising receptors, kinases, and scaffold proteins. In Helicobacter pylori, a stomach pathogen, chemotaxis is crucial for colonization, with CheV1 and CheW as key scaffold proteins. While both scaffolds are essential for building chemoreceptor complexes, their roles vary in other assays. Our research reexamines cheV1 mutants' behavior in semisolid agar, a standard chemotaxis test. Initially, cheV1 mutants exhibited defects similar to those of cheW mutants, but they evolved genetic suppressors that enhanced migration. These suppressors involve mutations in a previously uncharacterized gene, unknown in motility behavior. Our findings highlight the significant chemotaxis defects in cheV1 mutants and identify new elements influencing bacterial motility.

Unraveling the crystal structure of the HpaA adhesin: insights into cell adhesion function and epitope localization of a Helicobacter pylori vaccine candidate

Helicobacter pylori is a bacterium that exhibits strict host restriction to humans and non-human primates, and the bacterium is widely acknowledged as a significant etiological factor in the development of chronic gastritis, peptic ulcers, and gastric cancers. The pathogenic potential of this organism lies in its adeptness at colonizing the gastric mucosa, which is facilitated by a diverse repertoire of virulence factors, including adhesins that promote the attachment of the bacteria to the gastric epithelium. Among these adhesins, HpaA stands out due to its conserved nature and pivotal role in establishing H. pylori colonization. Moreover, this lipoprotein holds promise as an antigen for the development of effective H. pylori vaccines, thus attracting considerable attention for in-depth investigations into its molecular function and identification of binding determinants. Here, we present the elucidation of the crystallographic structure of HpaA at 2.9 Å resolution. The folding adopts an elongated protein shape, which is distinctive to the Helicobacteraceae family, and features an apical domain extension that plays a critical role in the cell-adhesion activity on gastric epithelial cells. Our study also demonstrates the ability of HpaA to induce TNF-α expression in macrophages, highlighting a novel role as an immunoregulatory effector promoting the pro-inflammatory response in vitro. These findings not only contribute to a deeper comprehension of the multifaceted role of HpaA in H. pylori pathogenesis but also establish a fundamental basis for the design and development of structure-based derivatives, aimed at enhancing the efficacy of H. pylori vaccines.

IMPORTANCE

Helicobacter pylori is a bacterium that can cause chronic gastritis, peptic ulcers, and gastric cancers. The bacterium adheres to the lining of the stomach using proteins called adhesins. One of these proteins, HpaA, is particularly important for H. pylori colonization and is considered a promising vaccine candidate against H. pylori infections. In this work, we determined the atomic structure of HpaA, identifying a characteristic protein fold to the Helicobacter family and delineating specific amino acids that are crucial to support the attachment to the gastric cells. Additionally, we discovered that HpaA can trigger the production of TNF-α, a proinflammatory molecule, in macrophages. These findings provide valuable insights into how H. pylori causes disease and suggest that HpaA has a dual role in both attachment and immune activation. This knowledge could contribute to the development of improved vaccine strategies for preventing H. pylori infections.

Sensing the environment by bacterial plant pathogens: What do their numerous chemoreceptors recognize?

Bacteria have evolved multiple sensing strategies to efficiently adapt to their natural hosts and environments. In the context of plant pathology, chemotaxis allows phytopathogenic bacteria to direct their movement towards hosts through the detection of a landscape of plant-derived molecules, facilitating the initiation of the infective process. The importance of chemotaxis for the lifestyle of phytopathogens is also reflected in the fact that they have, on average, twice as many chemoreceptors as bacteria that do not interact with plants. Paradoxically, the knowledge about the function of plant pathogen chemoreceptors is scarce. Notably, many of these receptors seem to be specific to plant-interacting bacteria, suggesting that they may recognize plant-specific compounds. Here, we highlight the need to advance our knowledge of phytopathogen chemoreceptor function, which may serve as a base for the development of anti-infective therapies for the control of phytopathogens.

Microparticles and nanoparticles-based approaches to improve oral treatment of Helicobacter pylori infection

Helicobacter pylori is a gram-negative, spiral-shaped, flagellated bacterium that colonizes the stomach of half the world's population. Helicobacter pylori infection causes pathologies of varying severity. Standard oral therapy fails in 15-20% since the barriers of the oral route decrease the bioavailability of antibiotics and the intrinsic factors of bacteria increase the rates of resistance. Nanoparticles and microparticles are promising strategies for drug delivery into the gastric mucosa and targeting H. pylori. The variety of building blocks creates systems with distinct colloidal, surface, and biological properties. These features improve drug-pathogen interactions, eliminate drug depletion and overuse, and enable the association of multiple actives combating H. pylori on several fronts. Nanoparticles and microparticles are successfully used to overcome the barriers of the oral route, physicochemical inconveniences, and lack of selectivity of current therapy. They have proven efficient in employing promising anti-H. pylori compounds whose limitation is oral route instability, such as some antibiotics and natural products. However, the current challenge is the applicability of these strategies in clinical practice. For this reason, strategies employing a rational design are necessary, including in the development of nano- and microsystems for the oral route.

Efficacy and safety of probiotic-supplemented bismuth quadruple therapy for the treatment of Helicobacter pylori infection: a systematic review and meta-analysis

OBJECTIVE

We performed a meta-analysis to determine whether the addition of probiotics to the bismuth quadruple therapy (BQT) for Helicobacter pylori would improve the incidence of eradication and reduce that of side effects.

METHODS

Randomized controlled trials matching the inclusion criteria were collected from PubMed, Embase, Web of Science, and The Cochrane Central Register of Controlled Trials. A Mantel-Haenszel random-effects model was used to calculate pooled risk ratios (RRs) and 95% confidence intervals (CIs) for the incidences of eradication rate, side effects as a whole, diarrhea, and other side effects.

RESULTS

Ten studies were selected for inclusion in the meta-analysis. The pooled RRs for the eradication rates in intention-to-treat and per-protocol analyses of the probiotic group vs. the control group were 1.07 (95% CI: 1.02-1.11) and 1.04 (95% CI: 1.00-1.07), respectively. Probiotic supplementation reduced the incidences of side effects (RR 0.58, 95% CI: 0.37-0.91), diarrhea (RR 0.41, 95% CI: 0.25-0.67), and bitter taste (RR 0.63, 95% CI: 0.40-0.99).

CONCLUSIONS

The results of this meta-analysis support the use of probiotics in combination with BQT in the clinical management of patients with H. pylori infection.

Negative chemotaxis of Ligilactobacillus agilis BKN88 against gut-derived substances

Ligilactobacillus agilis is a motile lactic acid bacterium found in the gastrointestinal tracts of animals. The findings of our previous study suggest that the motility of L. agilis BKN88 enables gut colonization in murine models. However, the chemotactic abilities of motile lactobacilli remain unknown. This study aimed to identify the gut-derived chemoeffectors and their corresponding chemoreceptors in L. agilis BKN88. Chemotaxis assays with chemotactic and non-chemotactic (ΔcheA) L. agilis strains revealed that low pH, organic acids, and bile salts served as repellents. L. agilis BKN88 was more sensitive to bile and acid than the gut-derived non-motile lactobacilli, implying that L. agilis might utilize motility and chemotaxis instead of exhibiting stress tolerance/resistance. L. agilis BKN88 contains five putative chemoreceptor genes (mcp1-mcp5). Chemotaxis assays using a series of chemoreceptor mutants revealed that each of the five chemoreceptors could sense multiple chemoeffectors and that these chemoreceptors were functionally redundant. Mcp2 and Mcp3 sensed all tested chemoeffectors. This study provides further insights into the interactions between chemoreceptors and ligands of motile lactobacilli and the unique ecological and evolutionary features of motile lactobacilli, which may be distinct from those of non-motile lactobacilli.

Helicobacter pylori infection increases the risk of carotid plaque formation: Clinical samples combined with bioinformatics analysis

Objective

Infection with Helicobacter pylori (H. pylori) may increase atherosclerosis, which can lead to carotid plaque formation. Our study examined the relationship between H. pylori infection and carotid plaque formation, and its underlying mechanisms.

Methods

A total of 36,470 people who underwent physical examination in Taizhou Hospital Health Examination Center from June 2017 to June 2022 were included in this study. All people participated in the urease test, neck ultrasound, blood pressure detection, anthropometric measurement and biochemical laboratory examination. In addition, the GSE27411 and GSE28829 datasets in the Gene Expression Omnibus (GEO) database were used to analyze the mechanism of H. pylori infection and atherosclerosis progression.

Results

H. pylori infection, sex, age, blood lipids, blood pressure, fasting blood glucose, glycated hemoglobin and body mass index were risk factors for carotid plaque formation. An independent risk factor was still evident in the multivariate logistic regression analysis, indicating H. pylori infection. Furthermore, after weighted gene coexpression network analysis (WGCNA), we discovered 555 genes linked to both H. pylori infection and the advancement of atherosclerosis. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses revealed a strong correlation between these genes and immunity, infection, and immune disorders. SsGSEA analysis showed that H. pylori infection and atherosclerosis included changes in the immune microenvironment. Finally, three genes MS4A6A, ADAMDEC1 and AQP9 were identified to be involved in the formation of atherosclerosis after H. pylori infection. Conclusion: Our research affirms that H. pylori is a unique contributor to the formation of carotid plaque, examines the immune microenvironment associated with H. pylori infection and advanced carotid atherosclerosis, and offers fresh perspectives on how H. pylori infection leads to atherosclerosis.

Preparation of Corn Peptides with Anti-Adhesive Activity and Its Functionality to Alleviate Gastric Injury Induced by Helicobacter pylori Infection In Vivo

More than 50% of the world population is infected with Helicobacter pylori (H. pylori), which is classified as group I carcinogen by the WHO. H. pylori surface adhesins specifically recognize gastric mucosal epithelial cells' (GES-1 cells) receptor to complete the adhesion. Blocking the adhesion with an anti-adhesion compound is an effective way to prevent H. pylori infection. The present study found that corn protein hydrolysate, hydrolyzed by Neutral, effectively alleviated gastric injury induced by H. pylori infection through anti-adhesive and anti-inflammatory effects in vitro and in vivo. The hydrolysate inhibited H. pylori adhesion to GES-1 cells significantly, and its anti-adhesive activity was 50.44 ± 0.27% at 4 mg/mL, which indicated that the hydrolysate possessed a similar structure to the GES-1 cells' receptor, and exhibited anti-adhesive activity in binding to H. pylori. In vivo, compared with the H. pylori infection model group, the medium and high dose of the hydrolysate (400-600 mg/kg·bw) significantly decreased (p < 0.05) the amount of H. pylori colonization, pro-inflammatory cytokines (IL-6, IL-1β, TNF-α and MPO), chemokines (KC and MCP-1) as well as key metabolites of NF-κB signaling pathway levels (TLR4, MyD88 and NF-κB), and it increased antioxidant enzyme contents (SOD and GSH-Px) and the mitigation of H. pylori-induced pathological changes in the gastric mucosa. Taken together, these results indicated that the hydrolysate intervention can prevent H. pylori-induced gastric injury by anti-adhesive activity and inhibiting the NF-κB signaling pathway's induction of inflammation. Hence, the corn protein hydrolysate might act as a potential anti-adhesive agent to prevent H. pylori infection.

FTO-mediated m6A modification promotes malignant transformation of gastric mucosal epithelial cells in chronic Cag A+ Helicobacter pylori infection

OBJECTIVES

Cag A+ Helicobacter pylori chronic infection cause malignant transformation of the human gastric mucosa. N6-methyladenosine (m6A) modifications are the most common and abundant mRNA modifications and one of the pathways affecting tumorigenicity and tumor progression. However, the role of m6A modification in the process of chronic H. pylori infection leading to malignant transformation of gastric mucosa is unclear.

METHODS

In this study, we used Cag A- and Cag A+H. pylori chronic infection to establish cellular models in GES-1 cells and analyzed the cellular morphology, proliferation, apoptosis, invasiveness and tumorigenicity of gastric mucosal epithelial cells. The m6A expression levels of GES-1 cells after chronic infection with Cag A- and Cag A+H. pylori were examined, and modifying effect of FTO (the fat mass and obesity-associated protein) on CD44 was verified by MeRIP-qPCR. Finally, the FTO expression changes and m6A expression levels were further validated in clinical gastric cancer tissues.

RESULTS

Chronic Cag A+H. pylori-infected GES-1 cells exhibit altered cell morphology, apoptosis inhibition, abnormal proliferation, enhanced migration, colony formation, and increased stem cell-like properties. Meanwhile, FTO and CD44 expression was enhanced, and FTO may induce malignant transformation of gastric mucosa by regulating CD44 mRNA m6A methylation modifications.

CONCLUSIONS

We verified the effect of chronic stimulation of Cag A+H. pylori on malignant transformation of gastric mucosal epithelium. revealing the possibility of FTO in promoting malignant transformation of gastric mucosa by modifying CD44 mRNA methylation, suggesting that FTO expression is a potential molecule for malignant transformation of gastric mucosal epithelial cells.

Multiplexed microfluidic screening of bacterial chemotaxis

Microorganism sensing of and responding to ambient chemical gradients regulates a myriad of microbial processes that are fundamental to ecosystem function and human health and disease. The development of efficient, high-throughput screening tools for microbial chemotaxis is essential to disentangling the roles of diverse chemical compounds and concentrations that control cell nutrient uptake, chemorepulsion from toxins, and microbial pathogenesis. Here, we present a novel microfluidic multiplexed chemotaxis device (MCD) which uses serial dilution to simultaneously perform six parallel bacterial chemotaxis assays that span five orders of magnitude in chemostimulant concentration on a single chip. We first validated the dilution and gradient generation performance of the MCD, and then compared the measured chemotactic response of an established bacterial chemotaxis system (Vibrio alginolyticus) to a standard microfluidic assay. Next, the MCD's versatility was assessed by quantifying the chemotactic responses of different bacteria (Psuedoalteromonas haloplanktis, Escherichia coli) to different chemoattractants and chemorepellents. The MCD vastly accelerates the chemotactic screening process, which is critical to deciphering the complex sea of chemical stimuli underlying microbial responses.

Helicobacter pylori Chronic Infection Selects for Effective Colonizers of Metaplastic Glands

Chronic gastric infection with Helicobacter pylori can lead to progressive tissue changes that culminate in cancer, but how H. pylori adapts to the changing tissue environment during disease development is not fully understood. In a transgenic mouse gastric metaplasia model, we found that strains from unrelated individuals differed in their ability to infect the stomach, to colonize metaplastic glands, and to alter the expression of the metaplasia-associated protein TFF3. H. pylori isolates from different stages of disease from a single individual had differential ability to colonize healthy and metaplastic gastric glands. Exposure to the metaplastic environment selected for high gastric colonization by one of these strains. Complete genome sequencing revealed a unique alteration in the frequency of a variant allele of the putative adhesin sabB, arising from a recombination event with the related sialic acid binding adhesin (SabA) gene. Mutation of sabB in multiple H. pylori strain backgrounds strongly reduced adherence to both normal and metaplastic gastric tissue, and highly attenuated stomach colonization in mice. Thus, the changing gastric environment during disease development promotes bacterial adhesin gene variation associated with enhanced gastric colonization. IMPORTANCE Chronic infection with Helicobacter pylori is the primary risk factor for developing stomach cancer. As disease progresses H. pylori must adapt to a changing host tissue environment that includes induction of new cell fates in the cells that line the stomach. We tested representative H. pylori isolates collected from the same patient during early and later stages of disease in a mouse model where we can rapidly induce disease-associated tissue changes. Only the later-stage H. pylori strains could robustly colonize the diseased stomach environment. We also found that the ability to colonize the diseased stomach was associated with genetic variation in a putative cell surface adhesin gene called sabB. Additional experiments revealed that SabB promotes binding to stomach tissue and is critical for stomach colonization by the late-stage strains. Thus, H. pylori diversifies its genome during disease progression and these genomic changes highlight critical factors for bacterial persistence.

Helicobacter pylori Chronic-Stage Inflammation Undergoes Fluctuations That Are Altered in tlpA Mutants

Helicobacter pylori colonizes half of the world's population and is responsible for a significant disease burden by causing gastritis, peptic ulcers, and gastric cancer. The development of host inflammation drives these diseases, but there are still open questions in the field about how H. pylori controls this process. We characterized H. pylori inflammation using an 8-month mouse infection time course and comparison of the wild type (WT) and a previously identified mutant lacking the TlpA chemoreceptor that causes elevated inflammation. Our work shows that H. pylori chronic-stage corpus inflammation undergoes surprising fluctuations, with changes in Th17 and eosinophil numbers. The H. pylori tlpA mutant changed the inflammation temporal characteristics, resulting in different inflammation from the wild type at some time points. tlpA mutants have equivalent total and gland colonization in late-stage infections. During early infection, in contrast, they show elevated gland and total colonization compared to those by WT. Our results suggest the chronic inflammation setting is dynamic and may be influenced by colonization properties of early infection.

Mitochondrial Function in Health and Disease: Responses to Helicobacter pylori Metabolism and Impact in Gastric Cancer Development

Mitochondria are major cellular organelles that play an essential role in metabolism, stress response, immunity, and cell fate. Mitochondria are organized in a network with other cellular compartments, functioning as a signaling hub to maintain cells' health. Mitochondrial dysfunctions and genome alterations are associated with diseases including cancer. Mitochondria are a preferential target for pathogens, which have developed various mechanisms to hijack cellular functions for their benefit. Helicobacter pylori is recognized as the major risk factor for gastric cancer development. H. pylori induces oxidative stress and chronic gastric inflammation associated with mitochondrial dysfunction. Its pro-apoptotic cytotoxin VacA interacts with the mitochondrial inner membrane, leading to increased permeability and decreased ATP production. Furthermore, H. pylori induces mitochondrial DNA damage and mutation, concomitant with the development of gastric intraepithelial neoplasia as observed in infected mice. In this chapter, we present diverse aspects of the role of mitochondria as energy supplier and signaling hubs and their adaptation to stress conditions. The metabolic activity of mitochondria is directly linked to biosynthetic pathways. While H. pylori virulence factors and derived metabolites are essential for gastric colonization and niche adaptation, they may also impact mitochondrial function and metabolism, and may have consequences in gastric pathogenesis. Importantly, during its long way to reach the gastric epithelium, H. pylori faces various cellular types along the gastric mucosa. We discuss how the mitochondrial response of these different cells is affected by H. pylori and impacts the colonization and bacterium niche adaptation and point to areas that remain to be investigated.

Lactate causes downregulation of Helicobacter pylori adhesin genes sabA and labA while dampening the production of proinflammatory cytokines

Chronic inflammation induced by Helicobacter pylori is strongly associated with gastric cancer development, which is influenced by both bacterial virulence and host genetics. The sialic acid-binding adhesin SabA and the MUC5AC-binding adhesin LabA are important H. pylori virulence factors that facilitate adhesion of the bacterium, which is a crucial step in colonization. Lactate utilization has been reported to play a key role in the pathogenicity of different bacterial species. However, this is poorly understood in H. pylori. In this study, we investigated the effect of lactate on H. pylori adhesin gene expression and the regulation of host inflammatory cytokines. We show that the bacterial adhesins SabA and LabA were downregulated at the transcriptional level during incubation of H. pylori with lactate. Downregulation of sabA required the involvement of the two-component system ArsRS, while labA was regulated via the CheA/CheY system, indicating differences in the regulation of these genes in response to lactate. The levels of the proinflammatory cytokines TNF and IL-6 in H. pylori-stimulated macrophages were reduced when lactate was present. Interestingly, glucose did not prevent the secretion of these cytokines. Taken together, our data suggest that lactate affects H. pylori adhesin gene expression and the host response upon infection.

Insights into the Orchestration of Gene Transcription Regulators in Helicobacter pylori

Bacterial pathogens employ a general strategy to overcome host defenses by coordinating the virulence gene expression using dedicated regulatory systems that could raise intricate networks. During the last twenty years, many studies of Helicobacter pylori, a human pathogen responsible for various stomach diseases, have mainly focused on elucidating the mechanisms and functions of virulence factors. In parallel, numerous studies have focused on the molecular mechanisms that regulate gene transcription to attempt to understand the physiological changes of the bacterium during infection and adaptation to the environmental conditions it encounters. The number of regulatory proteins deduced from the genome sequence analyses responsible for the correct orchestration of gene transcription appears limited to 14 regulators and three sigma factors. Furthermore, evidence is accumulating for new and complex circuits regulating gene transcription and H. pylori virulence. Here, we focus on the molecular mechanisms used by H. pylori to control gene transcription as a function of the principal environmental changes.

Methylation-Independent Chemotaxis Systems Are the Norm for Gastric-Colonizing Helicobacter Species

Many bacteria and archaea rely on chemotaxis signal transduction systems for optimal fitness. These complex, multiprotein signaling systems have core components found in all chemotactic microbes, as well as variable proteins found in only some species. We do not yet understand why these variations exist or whether there are specific niches that favor particular chemotaxis signaling organization. One variation is in the presence/absence of the chemotaxis methylation adaptation enzymes CheB and CheR. Genes for CheB and CheR are missing in the gastric pathogen Helicobacter pylori but present in related Helicobacter that colonize the liver or intestine. In this work, we asked whether there was a general pattern of CheB/CheR across multiple Helicobacter species. Helicobacter spp. all possess chemotactic behavior, based on the presence of genes for core signaling proteins CheA, CheW, and chemoreceptors. Genes for the CheB and CheR proteins, in contrast, were variably present. Niche mapping supported the idea that these genes were present in enterohepatic Helicobacter species and absent in gastric ones. We then analyzed whether there were differences between gastric and enterohepatic species in the CheB/CheR chemoreceptor target methylation sites. Indeed, these sites were less conserved in gastric species that lack CheB/CheR. Lastly, we determined that cheB and cheR could serve as markers to indicate whether an unknown Helicobacter species was of enterohepatic or gastric origin. Overall, these findings suggest the interesting idea that methylation-based adaptation is not required in specific environments, particularly the stomach. IMPORTANCE Chemotaxis signal transduction systems are common in the archaeal and bacterial world, but not all systems contain the same components. The rationale for this system variation remains unknown. In this report, comparative genomics analysis showed that the presence/absence of CheR and CheB is one main variation within the Helicobacter genus, and it is strongly associated with the niche of Helicobacter species: gastric Helicobacter species, which infect animal stomachs, have lost their CheB and CheR, while enterohepatic Helicobacter species, which infect the liver and intestine, retain them. This study not only provides an example that a chemotaxis system variant is associated with particular niches but also proposes that CheB and CheR are new markers distinguishing gastric from enterohepatic Helicobacter species.

Escherichia coli chemotaxis to competing stimuli in a microfluidic device with a constant gradient

In natural systems bacteria are exposed to many chemical stimulants; some attract chemotactic bacteria as they promote survival, while others repel bacteria because they inhibit survival. When faced with a mixture of chemoeffectors, it is not obvious which direction the population will migrate. Predicting this direction requires an understanding of how bacteria process information about their surroundings. We used a multiscale mathematical model to relate molecular level details of their two-component signaling system to the probability that an individual cell changes its swimming direction to the chemotactic velocity of a bacterial population. We used a microfluidic device designed to maintain a constant chemical gradient to compare model predictions to experimental observations. We obtained parameter values for the multiscale model of Escherichia coli chemotaxis to individual stimuli, α-methylaspartate and nickel ion, separately. Then without any additional fitting parameters, we predicted bacteria response to chemoeffector mixtures. Migration of E. coli toward α-methylaspartate was modulated by adding increasing concentrations of nickel ion. Thus, the migration direction was controlled by the relative concentrations of competing chemoeffectors in a predictable way. This study demonstrated the utility of a multiscale model to predict the migration direction of bacteria in the presence of competing chemoeffectors. This article is protected by copyright. All rights reserved.

Evaluation of mutagenesis, necrosis and apoptosis induced by omeprazole in stomach cells of patients with gastritis

BACKGROUND

Gastritis is a superficial and prevalent inflammatory lesion that is considered a public health concern once can cause gastric ulcers and gastric cancer, especially when associated with Helicobacter pylori infection. Proton pump inhibitors, such as omeprazole, are the most widely used drugs to treat this illness. The aim of the study was evaluate cytogenetic effects of omeprazole in stomach epithelial cells of patients with gastritis in presence and absence of H. pylori, through cytogenetic biomarkers and catalse and superoxide dismutase analysis.

METHODS

The study included 152 patients from the Gastroenterology Outpatient Clinic of Hospital Getúlio Vargas, Teresina-Brazil, that reported continuous and prolonged omeprazole use in doses of 20, 30 and 40 mg/kg. The participants were divided into groups: (1) patients without gastritis (n = 32); (2) patients without gastritis but with OME use (n = 24); (3) patients with gastritis (n = 26); (4) patients with gastritis undergoing OME therapy (n = 26); (5) patients with gastritis and H. pylori (n = 22) and (6) patients with gastritis and H. pylori on OME therapy (n = 22).

RESULTS

OME induced cytogenetic imbalance in the stomach epithelium through the formation of micronuclei (group 6 > 1, 2, 3, 4, 5; group 5 > 1, 2, 3; group 4 > 1, 2, 3); bridges (groups 4 and 6 > 1, 2, 3, 5 and group 2 > 3, 5); buds (groups 2,4,6 > , 1, 3, 5); binucleated cells (group 6 > 1, 2, 3, 4, 5; group 4 > 1, 2, 3); (groups 2 and 3 > 1); picnoses (group 6 > 1, 2, 3, 4, 5), groups 2 and 5 > 1, 3; group 4 > 1, 2, 3, 5); cariorrexis (groups 6 and 4 > 1, 2, 3, 5; groups 2, 3, 5 > 1) and karyolysis (groups 2, 4, and 6 > 1, 3, 5; groups 3 and 5 > 1). The OME cytogenetic instability was associated with H. pylori infection, indicating clastogenic/aneugenic effects, chromosomes alterations, gene expression changes, cytotoxicity and apoptosis.

CONCLUSIONS

The cytogenetic changescan be attributed to several mechanisms that are still unclear, including oxidative damage, as observed by increased catalase and superoxide dismutase expresion. Positive correlations between antioxidant enzymes were found with micronuclei formation, and were negative for picnoses. Thus, the continuous and prolonged omeprazole use induces genetic instability, which can be monitored through cytogenetic analyzes, as precursor for gastric cancer.

Identification of Antimotilins, Novel Inhibitors of Helicobacter pylori Flagellar Motility That Inhibit Stomach Colonization in a Mouse Model

New treatment options against the widespread cancerogenic gastric pathogen Helicobacter pylori are urgently needed. We describe a novel screening procedure for inhibitors of H. pylori flagellar biosynthesis. The assay is based on a flaA flagellin gene-luciferase reporter fusion in H. pylori and was amenable to multi-well screening formats with an excellent Z factor. We screened various compound libraries to identify virulence blockers ("antimotilins") that inhibit H. pylori motility or the flagellar type III secretion apparatus. We identified compounds that either inhibit both motility and the bacterial viability, or the flagellar system only, without negatively affecting bacterial growth. Novel anti-virulence compounds which suppressed flagellar biosynthesis in H. pylori were active on pure H. pylori cultures in vitro and partially suppressed motility directly, reduced flagellin transcript and flagellin protein amounts. We performed a proof-of-principle treatment study in a mouse model of chronic H. pylori infection and demonstrated a significant effect on H. pylori colonization for one antimotilin termed Active2 even as a monotherapy. The diversity of the intestinal microbiota was not significantly affected by Active2. In conclusion, the novel antimotilins active against motility and flagellar assembly bear promise to complement commonly used antibiotic-based combination therapies for treating and eradicating H. pylori infections. IMPORTANCE Helicobacter pylori is one of the most prevalent bacterial pathogens, inflicting hundreds of thousands of peptic ulcers and gastric cancers to patients every year. Antibacterial treatment of H. pylori is complicated due to the need of combining multiple antibiotics, entailing serious side effects and increasing selection for antibiotic resistance. Here, we aimed to explore novel nonantibiotic approaches to H. pylori treatment. We selected an antimotility approach since flagellar motility is essential for H. pylori colonization. We developed a screening system for inhibitors of H. pylori motility and flagellar assembly, and identified numerous novel antibacterial and anti-motility compounds (antimotilins). Selected compounds were further characterized, and one was evaluated in a preclinical therapy study in mice. The antimotilin compound showed a good efficacy to reduce bacterial colonization in the model, such that the antimotilin approach bears promise to be further developed into a therapy against H. pylori infection in humans.

Plant-Based Polyphenols: Anti-Helicobacter pylori Effect and Improvement of Gut Microbiota

Helicobacter pylori (H. pylori) infection affects more than half of the world’s population, and thus, about 10 to 20% of people with H. pylori suffer from peptic ulcers, which may ultimately lead to gastric cancer. The increase in antibiotic resistance and susceptibility has encouraged the search for new alternative therapies to eradicate this pathogen. Several plant species are essential sources of polyphenols, and these bioactive compounds have demonstrated health-promoting properties, such as the gut microbiota stimulation, inflammation reduction, and bactericidal effect. Therefore, this review aims to discuss the potential effect of plant-based polyphenols against H. pylori and their role in the gut microbiota improvement.

Under the Radar: Strategies Used by Helicobacter pylori to Evade Host Responses

The body depends on its physical barriers and innate and adaptive immune responses to defend against the constant assault of potentially harmful microbes. In turn, successful pathogens have evolved unique mechanisms to adapt to the host environment and manipulate host defenses. Helicobacter pylori (Hp), a human gastric pathogen that is acquired in childhood and persists throughout life, is an example of a bacterium that is very successful at remodeling the host-pathogen interface to promote a long-term persistent infection. Using a combination of secreted virulence factors, immune subversion, and manipulation of cellular mechanisms, Hp can colonize and persist in the hostile environment of the human stomach. Here, we review the most recent and relevant information regarding how this successful pathogen overcomes gastric epithelial host defense responses to facilitate its own survival and establish a chronic infection. Expected final online publication date for the Annual Review of Physiology, Volume 84 is February 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

What is the Sugar Code?

A code is defined by the nature of the symbols, which are used to generate information‐storing combinations (e. g. oligo‐ and polymers). Like nucleic acids and proteins, oligo‐ and polysaccharides are ubiquitous, and they are a biochemical platform for establishing molecular messages. Of note, the letters of the sugar code system (third alphabet of life) excel in coding capacity by making an unsurpassed versatility for isomer (code word) formation possible by variability in anomery and linkage position of the glycosidic bond, ring size and branching. The enzymatic machinery for glycan biosynthesis (writers) realizes this enormous potential for building a large vocabulary. It includes possibilities for dynamic editing/erasing as known from nucleic acids and proteins. Matching the glycome diversity, a large panel of sugar receptors (lectins) has developed based on more than a dozen folds. Lectins ‘read’ the glycan‐encoded information. Hydrogen/coordination bonding and ionic pairing together with stacking and C−H/π‐interactions as well as modes of spatial glycan presentation underlie the selectivity and specificity of glycan‐lectin recognition. Modular design of lectins together with glycan display and the nature of the cognate glycoconjugate account for the large number of post‐binding events. They give an entry to the glycan vocabulary its functional, often context‐dependent meaning(s), hereby building the dictionary of the sugar code.

A review on the structures and biological activities of anti-Helicobacter pylori agents

Helicobacter pylori is one of the main causal risk factor in the generation of chronic gastritis, gastroduodenal ulcers and gastric carcinoma. Thus, the eradication of H. pylori infection is an important way for preventing and managing the gastric diseases. Multiple-therapy with several antibacterial agents is used for the eradication of H. pylori infections; however the increase of resistance to H. pylori strains has resulted in unsatisfactory eradication and unsuccessful treatment. Furthermore, the combination therapy with high dosing leads to the disruption of intestinal microbial flora and undesired side effects. Therefore, the search for new therapeutic agents with high selectivity against H. pylori is a field of current interest. In recent years, diverse compounds originating from natural sources or synthetic drug design programs were evaluated and tried to optimize for applying against H. pylori. In this review, we have described various classes of anti-H. pylori compounds, their structure-activity relationship studies, and mechanism of actions, which could be useful for the development of new drugs for the treatment of H. pylori infections.

Design, expression, and purification of a multi-epitope vaccine against Helicobacter Pylori based on Melittin as an adjuvant

Helicobacter Pylori, a Gram-negative bacterium in the human stomach, causes adenocarcinoma and MALT (mucosa-associated lymphoid tissue) lymphoma in addition to infection and gastric ulcer. With regard to Helicobacter Pylori prevalence rate and widespread, producing an effective vaccine against this bacterium appears reasonable and necessary. Today, vaccine design by immunoinformatics is a promising solution in vaccine field. In the present study, potential immunodominant CD4⁺ T cell epitopes of UreB, HpaA, and NapA antigens were selected with a focus on IFN-γ secretion inducing ability. After joining the selected epitopes with KK and GPGPG linkers, sequence of Melittin, the major active protein of honey bee venom, was put in C-terminal by DPRVPSS linker as adjuvant. After reverse translation and codon optimization, the designed vaccine was cloned into pET-23a vector. The final construct was estimated as antigenic (71 & 74%) and non-allergenic with molecular weight of 36.785KD. The instability index (II) and codon frequency distribution were predicted to be 26.5 and 92%, respectively. The pET-23a vector transformed to the E.coli BL21 (DE3) strain. The evaluation of expression by SDS-PAGE analysis showed that the optimized expression is in SOB medium 8 h after induction by 0.5 mM IPTG. Finally, purification was performed by Ni-NTA affinity chromatography and Western blot analysis validated the purified protein. Future research is needed to investigate the designed vaccine efficiency against H. pylori, and also it's potential as a gastric cancer-preventive candidate.

Helicobacter pylori and association between its positivity and anatomotopographic settlement in the stomach with the host age range

Helicobacter pylori (H. pylori) is a Gram-negative, helically shaped flagellated bacterium. Major diseases associated with H. pylori infection include peptic ulcer, gastric adenocarcinoma, and mucosa-associated lymphoid tissue lymphoma. The incidence of H. pylori in the anatomotopographic regions of the stomach, such as antrum, corpus, fundus, and incisura angularis, has been investigated. Do the rates of H. pylori in the settlements change over time according to the age ranges of the hosts? Does this change affect the diseases caused by or related to H. pylori? It is estimated that the outcomes, which have been obtained, may provide a new perspective in terms of understanding the etiopathogenesis of H. pylori-induced diseases. A comprehensive literature search of PubMed/MEDLINE databases had been conducted using a combination of terms, “Helicobacter pylori,” “Sydney System,” “stomach,” “pyloric antrum,” “gastric corpus,” “stomach cancer,” and “Helicobacter pylori and age.” There are very few articles examining the relationship between the topographic locations of H. pylori and host age range in the English language literature. Therefore, it is also purposed to emphasize the outcomes of our current research about the mentioned topic. In our opinion, similar studies should reveal the settlement and age range in the different geographic locations and societies as in our study. We believe that these findings will contribute to the efforts for understanding overtly of H. pylori-induced disease of the stomach.

Helicobacter pylori adhesins: HpaA a potential antigen in experimental vaccines for H. pylori

BACKGROUND

Helicobacter pylori is a gram-negative bacterium involved in many gastric pathologies such as ulcers and cancers. Although the treatment for this infection has existed for several years, the development of a vaccine is nevertheless necessary to reduce the severe forms of the disease. For more than three decades, many advances have been made particularly in the understanding of virulence factors as well as the pathogenesis of gastric diseases caused by H. pylori. Among these key virulence factors, specific antigens have been identified: Urease, Vacuolating cytotoxin A (VacA), Cytotoxin-associated gene A (CagA), Blood group antigen-binding adhesin (BabA), H. pylori adhesin A (HpaA), and others.

OBJECTIVES

This review will focus on H. pylori adhesins, in particular, on HpaA and on the current knowledge of H. pylori vaccines.

METHODS

All of the information included in this review was retrieved from published studies on H. pylori adhesins in H. pylori infections.

RESULTS

These proteins, used in their native or recombinant forms, induce protection against H. pylori in experimental animal models.

CONCLUSION

H. pylori adhesins are known to be promising candidate vaccines against H. pylori. Future research should be carried out on adhesins, in particular, on HpaA.

Helicobacter pylori diversification during chronic infection within a single host generates sub-populations with distinct phenotypes

Helicobacter pylori chronically infects the stomach of approximately half of the world's population. Manifestation of clinical diseases associated with H. pylori infection, including cancer, is driven by strain properties and host responses; and as chronic infection persists, both are subject to change. Previous studies have documented frequent and extensive within-host bacterial genetic variation. To define how within-host diversity contributes to phenotypes related to H. pylori pathogenesis, this project leverages a collection of 39 clinical isolates acquired prospectively from a single subject at two time points and from multiple gastric sites. During the six years separating collection of these isolates, this individual, initially harboring a duodenal ulcer, progressed to gastric atrophy and concomitant loss of acid secretion. Whole genome sequence analysis identified 1,767 unique single nucleotide polymorphisms (SNPs) across isolates and a nucleotide substitution rate of 1.3x10-4 substitutions/site/year. Gene ontology analysis identified cell envelope genes among the genes with excess accumulation of nonsynonymous SNPs (nSNPs). A maximum likelihood tree based on genetic similarity clusters isolates from each time point separately. Within time points, there is segregation of subgroups with phenotypic differences in bacterial morphology, ability to induce inflammatory cytokines, and mouse colonization. Higher inflammatory cytokine induction in recent isolates maps to shared polymorphisms in the Cag PAI protein, CagY, while rod morphology in a subgroup of recent isolates mapped to eight mutations in three distinct helical cell shape determining (csd) genes. The presence of subgroups with unique genetic and phenotypic properties suggest complex selective forces and multiple niches within the stomach during chronic infection.

Differentially Expressed mRNAs and Their Long Noncoding RNA Regulatory Network with Helicobacter pylori-Associated Diseases including Atrophic Gastritis and Gastric Cancer

Background

Helicobacter pylori (Hp) infection is the strongest risk factor for gastric cancer (GC). However, the mechanisms of Hp-associated GC remain to be explored.

Methods

The gene expression profiling (GSE111762) data were downloaded from the GEO database. Differentially expressed genes (DEGs) between normal samples (NO) and Hp-atrophic gastritis (GA) or Hp-GA and Hp-GC were identified by GEO2R. Gene Ontology and pathway enrichment analysis were performed using the DAVID database. lncRNA-TF-mRNA and ceRNA regulation networks were constructed using Cytoscape. The cross-networks were obtained by overlapping molecules of the above two networks. GSE27411 and GSE116312 datasets were employed for validation.

Results

DEGs between NO and Hp-GA are linked to the activity of inward rectifying potassium channels, digestion, etc. DEGs between Hp-GA and Hp-GC were associated with digestion, positive regulation of cell proliferation, etc. According to the lncRNA-TF-mRNA network, 63 lncRNAs, 12 TFs, and 209 mRNAs were involved in Hp-GA while 16 lncRNAs, 11 TFs, and 92 mRNAs were contained in the Hp-GC network. In terms of the ceRNA network, 120 mRNAs, 18 miRNAs, and 27 lncRNAs were shown in Hp-GA while 72 mRNAs, 8 miRNAs, and 1 lncRNA were included in the Hp-GC network. In the cross-network, we found that immune regulation and differentiation regulation were important in the process of NO-GA. Neuroendocrine regulation was mainly related to the process of GA-GC. In the end, we verified that CDX2 plays an important role in the pathological process of NO to Hp-GA. Comparing Hp-GA with Hp-GC, DEGs (FPR1, TFF2, GAST, SST, FUT9, and SHH), TF, and GATA5 were of great significance.

Conclusions

We identified the DEGs, and their lncRNA regulatory network of Hp-associated diseases might provide insights into the mechanism between Hp infection and GC. Furthermore, in-depth studies of the molecules might be useful to explore the multistep process of gastric diseases.

Wheat Germ-Derived Peptides Exert Antiadhesive Activity against Helicobacter pylori: Insights into Structural Characteristics of Identified Peptides

Approximately 50-80% of the world population are infected with H. pylori, which is categorized as a class I carcinogen. Antiadhesive therapy is emerging as a promising alternative to antibiotics against bacterial infection. This study demonstrated that defatted wheat germ protein hydrolysates (DWGPH) effectively inhibited H. pylori adhesion to gastric epithelial cells. DWGPH prepared by pronase possessed the best activity where its inhibitory percentage at 10 mg/mL was 51.7 ± 6.8% and the minimum antiadhesive concentration was 0.31 mg/mL. The antiadhesive activity is attributable to peptides acting as receptor analogs in binding to H. pylori. Peptides with potential H. pylori-binding ability (n = 267) were identified, and their structural characteristics were comprehensively analyzed, including net charge, Boman index, instability index, aliphatic index, molecular weight, isoelectric point, hydrophobicity, and Hmoment (α-helix and β-sheet). This work provided an array of peptide sequences for further exploration as putative ligands of H. pylori adhesins and for elucidating molecular mechanisms.

Pathways of Gastric Carcinogenesis, Helicobacter pylori Virulence and Interactions with Antioxidant Systems, Vitamin C and Phytochemicals

Helicobacter pylori is a class one carcinogen which causes chronic atrophic gastritis, gastric intestinal metaplasia, dysplasia and adenocarcinoma. The mechanisms by which H. pylori interacts with other risk and protective factors, particularly vitamin C in gastric carcinogenesis are complex. Gastric carcinogenesis includes metabolic, environmental, epigenetic, genomic, infective, inflammatory and oncogenic pathways. The molecular classification of gastric cancer subtypes has revolutionized the understanding of gastric carcinogenesis. This includes the tumour microenvironment, germline mutations, and the role of Helicobacter pylori bacteria, Epstein Barr virus and epigenetics in somatic mutations. There is evidence that ascorbic acid, phytochemicals and endogenous antioxidant systems can modify the risk of gastric cancer. Gastric juice ascorbate levels depend on dietary intake of ascorbic acid but can also be decreased by H. pylori infection, H. pylori CagA secretion, tobacco smoking, achlorhydria and chronic atrophic gastritis. Ascorbic acid may be protective against gastric cancer by its antioxidant effect in gastric cytoprotection, regenerating active vitamin E and glutathione, inhibiting endogenous N-nitrosation, reducing toxic effects of ingested nitrosodimethylamines and heterocyclic amines, and preventing H. pylori infection. The effectiveness of such cytoprotection is related to H. pylori strain virulence, particularly CagA expression. The role of vitamin C in epigenetic reprogramming in gastric cancer is still evolving. Other factors in conjunction with vitamin C also play a role in gastric carcinogenesis. Eradication of H. pylori may lead to recovery of vitamin C secretion by gastric epithelium and enable regression of premalignant gastric lesions, thereby interrupting the Correa cascade of gastric carcinogenesis.

Using Probiotics as Supplementation for Helicobacter pylori Antibiotic Therapy

Helicobacter pylori is a well-known pathogen that is highly prevalent in the world population, and H. pylori infection is potentially hazardous to humans because of its relationship to various gastrointestinal diseases, such as gastric ulcers, chronic gastritis, and gastric carcinoma. Therefore, the clinical guidelines recommend taking antibiotic therapy to eradicate the pathogen, which usually leads to the desired therapeutic effect. However, some failure cases of this therapy indicate that the increasing antibiotic resistance and side effects may affect the therapeutic effect. Here we propose that using probiotics as supplementation for antibiotic therapy may provide an extra help. Recent studies have shown that probiotic supplementation therapy has promising application prospects; it can enhance the antibiotic effect to achieve a better therapeutic result and maintain the balance of the host gastrointestinal microbiota. In summary, under global conditions of increasing H. pylori prevalence, probiotic supplementation therapy is worthy of further studies for future clinical application.

Chemotaxis and cyclic-di-GMP signalling control surface attachment of Escherichia coli

Attachment to surfaces is an important early step during bacterial infection and during formation of submerged biofilms. Although flagella-mediated motility is known to be important for attachment of Escherichia coli and other bacteria, implications of motility regulation by cellular signalling remain to be understood. Here, we show that motility largely promotes attachment of E. coli, including that mediated by type 1 fimbriae, by allowing cells to reach, get hydrodynamically trapped at and explore the surface. Inactivation or inhibition of the chemotaxis signalling pathway improves attachment by suppressing cell reorientations and thereby increasing surface residence times. The attachment is further enhanced by deletion of genes encoding the cyclic diguanosine monophosphate (c-di-GMP)-dependent flagellar brake YcgR or the diguanylate cyclase DgcE. Such increased attachment in absence of c-di-GMP signalling is in contrast to its commonly accepted function as a positive regulator of the sessile state. It is apparently due to the increased swimming speed of E. coli in absence of YcgR-mediated motor control, which strengthens adhesion mediated by the type 1 fimbriae. Thus, both signalling networks that regulate motility of E. coli also control its engagement with both biotic and abiotic surfaces, which has likely implications for infection and biofilm formation.

Inhibitory Effect of β-Carotene on Helicobacter pylori-Induced TRAF Expression and Hyper-Proliferation in Gastric Epithelial Cells

Helicobacter pylori infection causes the hyper-proliferation of gastric epithelial cells that leads to the development of gastric cancer. Overexpression of tumor necrosis factor receptor associated factor (TRAF) is shown in gastric cancer cells. The dietary antioxidant β-carotene has been shown to counter hyper-proliferation in H. pylori-infected gastric epithelial cells. The present study was carried out to examine the β-carotene mechanism of action. We first showed that H. pylori infection decreases cellular IκBα levels while increasing cell viability, NADPH oxidase activity, reactive oxygen species production, nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation, and TRAF1 and TRAF2 gene expression, as well as protein–protein interaction in gastric epithelial AGS cells. We then demonstrated that pretreatment of cells with β-carotene significantly attenuates these effects. Our findings support the proposal that β-carotene has anti-cancer activity by reducing NADPH oxidase-mediated production of ROS, NF-κB activation and NF-κB-regulated TRAF1 and TRAF2 gene expression, and hyper-proliferation in AGS cells. We suggest that the consumption of β-carotene-enriched foods could decrease the incidence of H. pylori-associated gastric disorders.

Helicobacter pylori Uses the TlpB Receptor To Sense Sites of Gastric Injury

Helicobacter pylori is a pathogen that chronically colonizes the stomachs of approximately half of the world's population and contributes to the development of gastric inflammation. We demonstrated previously in vivo that H. pylori uses motility to preferentially colonize injury sites in the mouse stomach. However, the chemoreceptor responsible for sensing gastric injury has not yet been identified. In this study, we utilized murine gastric organoids (gastroids) and mutant H. pylori strains to investigate the components necessary for H. pylori chemotaxis. High-intensity 730-nm light (two-photon photodamage) was used to cause single-cell damage in gastroids, and repair of the damage was monitored over time; complete repair occurred within ∼10 min in uninfected gastroids. Wild-type H. pylori accumulated at the damage site after gastric damage induction. In contrast, mutants lacking motility (ΔmotB) or chemotaxis (ΔcheY) did not accumulate at the injury site. Using mutants lacking individual chemoreceptors, we found that only TlpB was required for H. pylori accumulation, while TlpA, TlpC, and TlpD were dispensable. All strains that were able to accumulate at the damage site limited repair. When urea (an identified chemoattractant sensed by TlpB) was microinjected into the gastroid lumen, it prevented the accumulation of H. pylori at damage sites. Overall, our findings demonstrate that H. pylori colonizes and limits repair at damage sites via chemotactic motility that requires the TlpB chemoreceptor to sense signals generated by gastric epithelial cells.

Unraveling the factors and mechanism involved in persistence: Host-pathogen interactions in Helicobacter pylori

Helicobacter pylori and humans have one of the most complex relationships in nature. How a bacterium manages to live in one of the harshest and hostile environments is a topic of unraveling mysteries. H. pylori is a prevalent species and it colonizes the human gut of more than 50% of the world population. It infects the epithelial region of antrum and persists there for a long period. Over the time of evolution, H. pylori has developed complex strategies to extend the degree of inflammation in gastric mucosa. H. pylori needs specific adaptations for initial colonization into the host environment like helical shape, flagellar movement, chemotaxis, and the production of urease enzyme that neutralizes acidic environment of the stomach. There are several factors from the bacterium as well as from the host that participate in these complex interactions. On the other hand, to establish the persistent infection, H. pylori escapes the immune system by mimicking the host antigens. This pathogen has the ability to dodge the immune system and then persist there in the form of host cell, which leads to immune tolerance. H. pylori has an ability to manipulate its own pathogen-associated molecular patterns, which leads to an inhibition in the binding with specific pattern recognition receptors of the host to avoid immune cell detection. Also, it manipulates the host metabolic homeostasis in the gastric epithelium. Besides, it has several genes, which may get involved in the acquisition of nutrition from the host to survive longer in the host. Due to the persistence of H. pylori, it causes chronic inflammation and raises the chances of gastric cancer. This review highlights the important elements, which are certainly responsible for the persistence of H. pylori in the human host.

Roles of Adhesion to Epithelial Cells in Gastric Colonization by Helicobacter pylori

Helicobacter pylori adherence to host epithelial cells is essential for its survival against the harsh conditions of the stomach and for successful colonization. Adherence of H. pylori is achieved through several related families of outer membrane proteins and proteins of a type IV secretion system (T4SS), which bridge H. pylori to host cells through protein-protein and other protein-ligand interactions. Local environmental conditions such as cell type, available host cell surface proteins and/or ligands, as well as responses by the host immune system force H. pylori to alter expression of these proteins to adapt quickly to the local environment in order to colonize and survive. Some of these host-pathogen interactions appear to function in a "catch-and-release" manner, regulated by reversible binding at varying pH and allowing H. pylori to detach itself from cells or debris sloughed off the gastric epithelial lining in order to return for subsequent productive interactions. Other interactions between bacterial adhesin proteins and host adhesion molecules, however, appear to function as a committed step in certain pathogenic processes, such as translocation of the CagA oncoprotein through the H. pylori T4SS and into host gastric epithelial cells. Understanding these adhesion interactions is critical for devising new therapeutic strategies, as they are responsible for the earliest stage of infection and its maintenance. This review will discuss the expression and regulation of several outer membrane proteins and CagL, how they engage their known host cell protein/ligand targets, and their effects on clinical outcome.

Screening natural libraries of human milk oligosaccharides against lectins using CaR-ESI-MS

Human milk oligosaccharides (HMOs) afford many health benefits to breast-fed infants, such as protection against infection and regulation of the immune system, through the formation of non-covalent interactions with protein receptors. However, the molecular details of these interactions are poorly understood. Here, we describe the application of catch-and-release electrospray ionization mass spectrometry (CaR-ESI-MS) for screening natural libraries of HMOs against lectins. The HMOs in the libraries were first identified based on molecular weights (MWs), ion mobility separation arrival times (IMS-ATs) and collision-induced dissociation (CID) fingerprints of their deprotonated anions. The libraries were then screened against lectins and the ligands identified from the MWs, IMS-ATs and CID fingerprints of HMOs released from the lectin in the gas phase. To demonstrate the assay, four fractions, extracted from pooled human milk and containing ≥35 different HMOs, were screened against a C-terminal fragment of human galectin-3 (hGal-3C), for which the HMOs specificities have been previously investigated, and a fragment of the blood group antigen-binding adhesin (BabA) from Helicobacter pylori, for which the HMO specificities have not been previously established. The structures of twenty-one ligands, corresponding to both neutral and acidic HMOs, of hGal-3C were identified; all twenty-one were previously shown to be ligands for this lectin. The presence of HMO ligands at six other MWs was also ascertained. Application of the assay to BabA revealed nineteen specific HMO structures that are recognized by the protein and HMO ligands at two other MWs. Notably, it was found that BabA exhibits broad specificity for HMOs, and recognizes both neutral HMOs, including non-fucosylated ones, and acidic HMOs. The results of competitive binding experiments indicate that HMOs can interact with BabA at previously unknown binding sites. The affinities of eight purified HMOs for BabA were measured by ESI-MS and found to be in the 10³ M^-1 to 10⁴ M^-1 range.

Control of bacterial colonization in the glands and crypts

The epithelial cell layer of the major organs of the mammalian gastrointestinal (GI) tract is extensively invaginated into thousands of gland and crypt structures. These are lined by distinct sets of epithelial cells and may comprise discrete niches. The host maximizes the distance between the epithelial cell layer and GI-inhabiting microbes to limit inflammation, and these strategies also likely keep bacteria out of the glands and crypts. We discuss here the specific host processes that have been shown to restrict bacterial presence in the glands and crypts, specifically the immune system, acid, mucin, oxygen, and reactive oxygen species. Not surprisingly, microbes have evolved sophisticated strategies to overcome these host factors and reside close to the epithelium in the glands and crypts. Bacterial properties important for gland and crypt colonization include bacterial immunomodulatory molecules, chemotaxis, and the use of certain metabolites. Overall, these as-yet limited studies suggest there are specific host and bacterial properties that control gland and crypt colonization, contributing to the overall microbial spatial organization of the GI tract. However, there remains much to be discovered in this area.

The effect of bacterial chemotaxis on host infection and pathogenicity

Chemotaxis enables microorganisms to move according to chemical gradients. Although this process requires substantial cellular energy, it also affords key physiological benefits, including enhanced access to growth substrates. Another important implication of chemotaxis is that it also plays an important role in infection and disease, as chemotaxis signalling pathways are broadly distributed across a variety of pathogenic bacteria. Furthermore, current research indicates that chemotaxis is essential for the initial stages of infection in different human, animal and plant pathogens. This review focuses on recent findings that have identified specific bacterial chemoreceptors and corresponding chemoeffectors associated with pathogenicity. Pathogenicity-related chemoeffectors are either host and niche-specific signals or intermediates of the host general metabolism. Plant pathogens were found to contain an elevated number of chemotaxis signalling genes and functional studies demonstrate that these genes are critical for their ability to enter the host. The expanding body of knowledge of the mechanisms underlying chemotaxis in pathogens provides a foundation for the development of new therapeutic strategies capable of blocking infection and preventing disease by interfering with chemotactic signalling pathways.

Helicobacter pylori Biofilm Involves a Multigene Stress-Biased Response, Including a Structural Role for Flagella

Biofilms, communities of bacteria that are embedded in a hydrated matrix of extracellular polymeric substances, pose a substantial health risk and are key contributors to many chronic and recurrent infections. Chronicity and recalcitrant infections are also common features associated with the ulcer-causing human pathogen H. pylori. However, relatively little is known about the role of biofilms in H. pylori pathogenesis, as well as the biofilm structure itself and the genes associated with this mode of growth. In the present study, we found that H. pylori biofilm cells highly expressed genes related to cell envelope and stress response, as well as those encoding the flagellar apparatus. Flagellar filaments were seen in high abundance in the biofilm. Flagella are known to play a role in initial biofilm formation, but typically are downregulated after that state. H. pylori instead appears to have coopted these structures for nonmotility roles, including a role building a robust biofilm.

Helicobacter pylori has an impressive ability to persist chronically in the human stomach. Similar characteristics are associated with biofilm formation in other bacteria. The H. pylori biofilm process, however, is poorly understood. To gain insight into this mode of growth, we carried out comparative transcriptomic analysis between H. pylori biofilm and planktonic cells, using the mouse-colonizing strain SS1. Optimal biofilm formation was obtained with a low concentration of serum and 3 days of growth, conditions that caused both biofilm and planktonic cells to be ∼80% coccoid. Transcriptome sequencing (RNA-seq) analysis found that 8.18% of genes were differentially expressed between biofilm and planktonic cell transcriptomes. Biofilm-downregulated genes included those involved in metabolism and translation, suggesting these cells have low metabolic activity. Biofilm-upregulated genes included those whose products were predicted to be at the cell envelope, involved in regulating a stress response, and surprisingly, genes related to formation of the flagellar apparatus. Scanning electron microscopy visualized flagella that appeared to be a component of the biofilm matrix, supported by the observation that an aflagellated mutant displayed a less robust biofilm with no apparent filaments. We observed flagella in the biofilm matrix of additional H. pylori strains, supporting that flagellar use is widespread. Our data thus support a model in which H. pylori biofilm involves a multigene stress-biased response and that flagella play an important role in H. pylori biofilm formation.

Chemotaxis of Escherichia coli to major hormones and polyamines present in human gut

The microorganisms in the gastrointestinal (GI) tract can influence the metabolism, immunity, and behavior of animal hosts. Increasing evidence suggests that communication between the host and the microbiome also occurs in the opposite direction, with hormones and other host-secreted compounds being sensed by microorganisms. Here, we addressed one key aspect of the host–microbe communication by studying chemotaxis of a model commensal bacterium, Escherichia coli, to several compounds present abundantly in the GI tract, namely catecholamines, thyroid hormones, and polyamines. Our results show that E. coli reacts to five out of ten analyzed chemicals, sensing melatonin, and spermidine as chemorepellents and showing mixed responses to dopamine, norepinephrine and 3,4-dihydroxymandelic acid. The strongest repellent response was observed for the polyamine spermidine, and we demonstrate that this response involves the low-abundance chemoreceptor Trg and the periplasmic binding protein PotD of the spermidine uptake system. The chemotactic effects of the tested compounds apparently correlate with their influence on growth and their stability in the GI tract, pointing to the specificity of the observed behavior. We hypothesize that the repellent responses observed at high concentrations of chemoeffective compounds might enable bacteria to avoid harmful levels of hormones and polyamines in the gut and, more generally, antimicrobial activities of the mucous layer.

Exploring the potential pharmacodynamic material basis and pharmacologic mechanism of the Fufang-Xialian-Capsule in chronic atrophic gastritis by network pharmacology approach based on the components absorbed into the blood

In this study, a new network pharmacology approach based on the components absorbed into the blood was used to investigate the pharmacodynamic material basis and the pharmacologic mechanism of the Fufang-Xialian-Capsule (FXL) in treating chronic atrophic gastritis (CAG). Initially, we confirmed the components absorbed into the blood by ultra-high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry. Then, the network approach, which was based on the results of components absorbed into the blood, was used to analyse the pharmacodynamic material basis and the pharmacologic mechanism of FXL on treating CAG. As a result, 22 absorbed components were found in rat plasma. Given the results of the absorption analysis of the components, eight pathways associated with CAG development were found. The targets linked to these pathways are the drug targets of FXL in CAG treatment. The components associated with these targets are the potential pharmacodynamic material basis and exert synergy in regulating pathways during CAG treatment.

The role of the LTB4-BLT1 axis in chemotactic gradient sensing and directed leukocyte migration

Directed leukocyte migration is a hallmark of inflammatory immune responses. Leukotrienes are derived from arachidonic acid and represent a class of potent lipid mediators of leukocyte migration. In this review, we summarize the essential steps leading to the production of LTB₄ in leukocytes. We discuss the recent findings on the exosomal packaging and transport of LTB₄ in the context of chemotactic gradients formation and regulation of leukocyte recruitment. We also discuss the dynamic roles of the LTB₄ receptors, BLT1 and BLT2, in mediating chemotactic signaling in leukocytes and contrast them to other structurally related leukotrienes that bind to distinct GPCRs. Finally, we highlight the specific roles of the LTB₄-BLT1 axis in mediating signal-relay between chemotaxing neutrophils and its potential contribution to a wide variety of inflammatory conditions including tumor progression and metastasis, where LTB₄ is emerging as a key signaling component.

Stimulus sensing and signal processing in bacterial chemotaxis

Motile bacteria use chemotaxis to migrate towards environments that are favorable for growth and survival. The signaling pathway that mediates this behavior is largely conserved among prokaryotes, with Escherichia coli chemotaxis system being one of the simplest and the best studied. At the core of this pathway are the arrays of clustered chemoreceptors that detect, amplify and integrate various stimuli. Recent work provided deeper understanding of spatial organization and signal processing by these clusters and uncovered the variety of sensory mechanisms used to detect environmental stimuli. Moreover, studies of bacteria with different lifestyles have led to new insights into the diversity and evolutionary conservation of the chemotaxis pathway, as well as the physiological relevance of chemotactic behavior in different environments.

Two Spatial Chemotaxis Assays: The Nutrient-Depleted Chemotaxis Assay and the Agarose-Plug-Bridge Assay

This chapter describes two spatial chemotaxis assays, the nutrient-depleted chemotaxis assay and agarose-plug-bridge assay, which enable the evaluation of putative chemoeffectors. These two assays have worked well with Campylobacter jejuni and Helicobacter pylori, and techniques for using these assays with these microbes are described.

Anti-Helicobacter pylori Properties of the Ant-Venom Peptide Bicarinalin

The venom peptide bicarinalin, previously isolated from the ant Tetramorium bicarinatum, is an antimicrobial agent with a broad spectrum of activity. In this study, we investigate the potential of bicarinalin as a novel agent against Helicobacter pylori, which causes several gastric diseases. First, the effects of synthetic bicarinalin have been tested against Helicobacter pylori: one ATCC strain, and forty-four isolated from stomach ulcer biopsies of Peruvian patients. Then the cytoxicity of bicarinalin on human gastric cells and murine peritoneal macrophages was measured using XTT and MTT assays, respectively. Finally, the preventive effect of bicarinalin was evaluated by scanning electron microscopy using an adherence assay of H. pylori on human gastric cells treated with bicarinalin. This peptide has a potent antibacterial activity at the same magnitude as four antibiotics currently used in therapies against H. pylori. Bicarinalin also inhibited adherence of H. pylori to gastric cells with an IC50 of 0.12 μg·mL-1 and had low toxicity for human cells. Scanning electron microscopy confirmed that bicarinalin can significantly decrease the density of H. pylori on gastric cells. We conclude that Bicarinalin is a promising compound for the development of a novel and effective anti-H. pylori agent for both curative and preventive use.

Colonization, localization, and inflammation: the roles of H. pylori chemotaxis in vivo

Helicobacter pylori is a Gram-negative bacterium that infects half of the world's population, causing gastritis, peptic ulcers, and gastric cancer. To establish chronic stomach infection, H. pylori utilizes chemotaxis, driven by a conserved signal transduction system. Chemotaxis allows H. pylori to sense an array of environmental and bacterial signals within the stomach, guiding its motility towards its preferred niche within the gastric mucosa and glands. Fine-tuned localization, regulated by the chemotaxis system, enables robust colonization during the acute stage of infection. During chronic infection, chemotaxis helps maintain bacterial populations and modulates the host immune response. Given its importance in host colonization and disease, chemotaxis is an attractive target for future treatments against H. pylori infections.