Helicobacter pylori is invasive and it may be a facultative intracellular organism

The Th1/Th2 paradigm: A misrepresentation of helper T cell plasticity

For decades, the Th1/2 paradigm has been used to classify immune responses as either Th1 or Th2-biased. However, in recent years, a staggering amount of evidence has emerged to support rejection of the classical Th1/Th2 paradigm, such as the discoveries of new helper T cell subsets, helper T cell plasticity and protective mixed-Th1/Th2 responses. This opinion piece investigates the shortcomings of classical Th1/Th2 paradigm in the context of recent works, with the goal of facilitating the development of newer models to represent the diversity of Th cells.

Cancer invasion and anaerobic bacteria: new insights into mechanisms

There is growing evidence that altered microbiota abundance of a range of specific anaerobic bacteria are associated with cancer, including Peptoniphilus spp., Porphyromonas spp., Fusobacterium spp., Fenollaria spp., Prevotella spp., Sneathia spp., Veillonella spp. and Anaerococcus spp. linked to multiple cancer types. In this review we explore these pathogenic associations. The mechanisms by which bacteria are known or predicted to interact with human cells are reviewed and we present an overview of the interlinked mechanisms and hypotheses of how multiple intracellular anaerobic bacterial pathogens may act together to cause host cell and tissue microenvironment changes associated with carcinogenesis and cancer cell invasion. These include combined effects on changes in cell signalling, DNA damage, cellular metabolism and immune evasion. Strategies for early detection and eradication of anaerobic cancer-associated bacterial pathogens that may prevent cancer progression are proposed.

LOX-1 acts as an N6-methyladenosine-regulated receptor for Helicobacter pylori by binding to the bacterial catalase

The role of N6-methyladenosine (m6A) modification of host mRNA during bacterial infection is unclear. Here, we show that Helicobacter pylori infection upregulates host m6A methylases and increases m6A levels in gastric epithelial cells. Reducing m6A methylase activity via hemizygotic deletion of methylase-encoding gene Mettl3 in mice, or via small interfering RNAs targeting m6A methylases, enhances H. pylori colonization. We identify LOX-1 mRNA as a key m6A-regulated target during H. pylori infection. m6A modification destabilizes LOX-1 mRNA and reduces LOX-1 protein levels. LOX-1 acts as a membrane receptor for H. pylori catalase and contributes to bacterial adhesion. Pharmacological inhibition of LOX-1, or genetic ablation of Lox-1, reduces H. pylori colonization. Moreover, deletion of the bacterial catalase gene decreases adhesion of H. pylori to human gastric sections. Our results indicate that m6A modification of host LOX-1 mRNA contributes to protection against H. pylori infection by downregulating LOX-1 and thus reducing H. pylori adhesion.

Association of Helicobacter pylori Infection with Autoimmune Thyroid Disease in the Female Sex

BACKGROUND

Helicobacter pylori infection has been associated with an increased risk of thyroid diseases (TDs), although scientific evidence is conflicting. In the present study the relationship between TDs, including both autoimmune (AI) and non-autoimmune TD, and H. pylori infection was investigated.

METHODS

Data from records of patients undergoing upper endoscopy and histologically evaluated for H. pylori infection were retrieved. In addition to demographic information, the features of gastritis based on non-targeted biopsies collected from the antrum, angulus, and corpus were analyzed. The presence of H. pylori infection and atrophy and/or metaplasia and/or dysplasia in at least one gastric specimen was defined as a long-lasting H. pylori infection and the presence of a chronic-active gastritis as a current infection. Hashimoto's and Graves' diseases were included in the AITD group, and thyroid nodules, goiter, iatrogenic thyroid hypo/hyper function, and thyroidectomy in the non-autoimmune TD group.

RESULTS

A total of 8322 records from adult patients from Northern Sardinia, characterized by a similar genetic background, was analyzed. Participants were aged 18-93 years (females 5339, 64.1%), and more specifically, 562 (6.7%) had a diagnosis of AITD and 448 (5.4%) of non-autoimmune TD. A significant association between long-lasting H. pylori and AITD (OR 1.34; 95%CI 1.13-1.60) was found, irrespective of age, sex, body mass index, and smoking status, while it was not associated with non-autoimmune TD. Current H. pylori infection did not show significant ORs for AITD (OR 0.99; 95%CI 0.64-1.57) and non-autoimmune TD (OR 0.86; 95%CI 0.66-1.15). The association with long-lasting H. pylori infection was confirmed to be significant for both Hashimoto's thyroiditis and Graves' disease by multivariable regression analysis. Stratification according to sex revealed a significant association only for females (OR 1.39; 95%CI 1.12-1.72).

CONCLUSIONS

Our results indicate that long-lasting H. pylori infection is associated with AITD in the female adult population of Northern Sardinia.

The interactions of Candida albicans with gut bacteria: a new strategy to prevent and treat invasive intestinal candidiasis

BACKGROUND

The gut microbiota plays an important role in human health, as it can affect host immunity and susceptibility to infectious diseases. Invasive intestinal candidiasis is strongly associated with gut microbiota homeostasis. However, the nature of the interaction between Candida albicans and gut bacteria remains unclear.

OBJECTIVE

This review aimed to determine the nature of interaction and the effects of gut bacteria on C. albicans so as to comprehend an approach to reducing intestinal invasive infection by C. albicans.

METHODS

This review examined 11 common gut bacteria's interactions with C. albicans, including Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii, Enterococcus faecalis, Staphylococcus aureus, Salmonella spp., Helicobacter pylori, Lactobacillus spp., Bacteroides spp., Clostridium difficile, and Streptococcus spp.

RESULTS

Most of the studied bacteria demonstrated both synergistic and antagonistic effects with C. albicans, and just a few bacteria such as P. aeruginosa, Salmonella spp., and Lactobacillus spp. demonstrated only antagonism against C. albicans.

CONCLUSIONS

Based on the nature of interactions reported so far by the literature between gut bacteria and C. albicans, it is expected to provide new ideas for the prevention and treatment of invasive intestinal candidiasis.

How Long Will It Take to Launch an Effective Helicobacter pylori Vaccine for Humans?

Helicobacter pylori infection often occurs in early childhood, and can last a lifetime if not treated with medication. H. pylori infection can also cause a variety of stomach diseases, which can only be treated with a combination of antibiotics. Combinations of antibiotics can cure H. pylori infection, but it is easy to relapse and develop drug resistance. Therefore, a vaccine is a promising strategy for prevention and therapy for the infection of H. pylori. After decades of research and development, there has been no appearance of any H. pylori vaccine reaching the market, unfortunately. This review summarizes the aspects of candidate antigens, immunoadjuvants, and delivery systems in the long journey of H. pylori vaccine research, and also introduces some clinical trials that have displayed encouraging or depressing results. Possible reasons for the inability of an H. pylori vaccine to be available over the counter are cautiously discussed and some propositions for the future of H. pylori vaccines are outlined.

Identification of PTPN20 as an innate immunity-related gene in gastric cancer with Helicobacter pylori infection

Background

Gastric cancer (GC) is among the deadliest diseases with countless incidences and deaths each year. Helicobacter pylori (Hp) is the primary type of microbe that colonizes the stomach. In recent years, increasing evidence has demonstrated that Hp infection is one of the main risk factors for GC. Elucidating the molecular mechanism of how Hp leads to GC will not only benefit the treatment of GC, but also boost the development of therapeutics for other gastric disorders caused by Hp infection. In this study, we aimed to identify innate immunity-related genes in GC and investigate their potentials as prognostic markers and therapeutic targets for Hp-related GC.

Methods

Firstly, we analyzed the differentially expressed innate immunity-related genes in GC samples from the TCGA database. Then prognostic correlation analysis was carried out to explore the prognostic value of these candidate genes. By combing transcriptome data, somatic mutation data, and clinical data, co-expression analysis, functional enrichment analysis, tumor mutational burden analysis, and immune infiltration analysis were performed to reveal the pathological relevance of the candidate gene. Finally, ceRNA network was constructed to identify the genes and pathways for the regulation of the candidate gene.

Results

We revealed that protein tyrosine phosphatase non-receptor type 20 (PTPN20) is a significant prognostic marker in Hp-related GC. Thus, PTPN20 levels have the potential to efficiently predict the survival of Hp-related GC patients. In addition, PTPN20 is associated with immune cell infiltration and tumor mutation burden in these GC patients. Moreover, we have also identified PTPN20-related genes, PTPN20 protein-protein interactions, and the PTPN20 ceRNA network.

Conclusion

Our data suggest that PTPN20 may have critical functions in Hp-related GC. Targeting PTPN20 may be a promising way to treat Hp-related GC.

Helicobacter pylori in the Oral Cavity: Current Evidence and Potential Survival Strategies

Helicobacter pylori (H. pylori) is transmitted primarily through the oral–oral route and fecal–oral route. The oral cavity had therefore been hypothesized as an extragastric reservoir of H. pylori, owing to the presence of H. pylori DNA and particular antigens in distinct niches of the oral cavity. This bacterium in the oral cavity may contribute to the progression of periodontitis and is associated with a variety of oral diseases, gastric eradication failure, and reinfection. However, the conditions in the oral cavity do not appear to be ideal for H. pylori survival, and little is known about its biological function in the oral cavity. It is critical to clarify the survival strategies of H. pylori to better comprehend the role and function of this bacterium in the oral cavity. In this review, we attempt to analyze the evidence indicating the existence of living oral H. pylori, as well as potential survival strategies, including the formation of a favorable microenvironment, the interaction between H. pylori and oral microorganisms, and the transition to a non-growing state. Further research on oral H. pylori is necessary to develop improved therapies for the prevention and treatment of H. pylori infection.

Host Cell Antimicrobial Responses against Helicobacter pylori Infection: From Biological Aspects to Therapeutic Strategies

The colonization of Helicobacter pylori (H. pylori) in human gastric mucosa is highly associated with the occurrence of gastritis, peptic ulcer, and gastric cancer. Antibiotics, including amoxicillin, clarithromycin, furazolidone, levofloxacin, metronidazole, and tetracycline, are commonly used and considered the major treatment regimens for H. pylori eradication, which is, however, becoming less effective by the increasing prevalence of H pylori resistance. Thus, it is urgent to understand the molecular mechanisms of H. pylori pathogenesis and develop alternative therapeutic strategies. In this review, we focus on the virulence factors for H. pylori colonization and survival within host gastric mucosa and the host antimicrobial responses against H. pylori infection. Moreover, we describe the current treatments for H. pylori eradication and provide some insights into new therapeutic strategies for H. pylori infection.

Helicobacter pylori, gastric microbiota and gastric cancer relationship: Unrolling the tangle

Helicobacter pylori infection (Hp-I) represents a typical microbial agent intervening in the complex mechanisms of gastric homeostasis by disturbing the balance between the host gastric microbiota and mucosa-related factors, leading to inflammatory changes, dysbiosis and eventually gastric cancer. The normal gastric microbiota shows diversity, with Proteobacteria [Helicobacter pylori (H. pylori) belongs to this family], Firmicutes, Actinobacteria, Bacteroides and Fusobacteria being the most abundant phyla. Most studies indicate that H. pylori has inhibitory effects on the colonization of other bacteria, harboring a lower diversity of them in the stomach. When comparing the healthy with the diseased stomach, there is a change in the composition of the gastric microbiome with increasing abundance of H. pylori (where present) in the gastritis stage, while as the gastric carcinogenesis cascade progresses to gastric cancer, the oral and intestinal-type pathogenic microbial strains predominate. Hp-I creates a premalignant environment of atrophy and intestinal metaplasia and the subsequent alteration in gastric microbiota seems to play a crucial role in gastric tumorigenesis itself. Successful H. pylori eradication is suggested to restore gastric microbiota, at least in primary stages. It is more than clear that Hp-I, gastric microbiota and gastric cancer constitute a challenging tangle and the strong interaction between them makes it difficult to unroll. Future studies are considered of crucial importance to test the complex interaction on the modulation of the gastric microbiota by H. pylori as well as on the relationships between the gastric microbiota and gastric carcinogenesis.

Multi-functional vesicles improve Helicobacter pylori eradication by a comprehensive strategy based on complex pathological microenvironment

Helicobacter pylori (H. pylori), creating a global infection rate over 50%, presents great challenges in clinical therapies due to its complex pathological microenvironment in vivo. To improve the eradication efficacy, herein we fabricated a pharmaceutical vesicle RHL/Cl-Ch-cal where cholesterol-PEG, calcitriol and first-line antibiotic clarithromycin were co-loaded in the rhamnolipid-composed outer lipid layer. RHL/Cl-Ch-cal could quickly penetrate through gastric mucus layer to reach H. pylori infection sites, and then effectively destroyed the architecture of H. pylori biofilms, killed dispersed H. pylori and inhibited the re-adhesion of residual bacteria (called biofilms eradication tetralogy). Moreover, RHL/Cl-Ch-cal activated the host immune response to H. pylori by replenishing cholesterol to repair lipid raft on the cell membrane of host epithelial cells. Finally, RHL/Cl-Ch-cal killed the intracellular H. pylori through recovering the lysosomal acidification and assisting degradation. In experiments, RHL/Cl-Ch-cal demonstrated prominent anti-H. pylori efficacy in the classical H. pylori-infected mice model. Therefore, the study provides a “comprehensive attack” strategy for anti-H. pylori therapies including biofilms eradication tetralogy, immune activation and intracellular bacteria killing.

Improving Antibacterial Activity of a HtrA Protease Inhibitor JO146 against Helicobacter pylori: A Novel Approach Using Microfluidics-Engineered PLGA Nanoparticles

Nanoparticle drug delivery systems have emerged as a promising strategy for overcoming limitations of antimicrobial drugs such as stability, bioavailability, and insufficient exposure to the hard-to-reach bacterial drug targets. Although size is a vital colloidal feature of nanoparticles that governs biological interactions, the absence of well-defined size control technology has hampered the investigation of optimal nanoparticle size for targeting bacterial cells. Previously, we identified a lead antichlamydial compound JO146 against the high temperature requirement A (HtrA) protease, a promising antibacterial target involved in protein quality control and virulence. Here, we reveal that JO146 was active against Helicobacter pylori with a minimum bactericidal concentration of 18.8–75.2 µg/mL. Microfluidic technology using a design of experiments approach was utilized to formulate JO146-loaded poly(lactic-co-glycolic) acid nanoparticles and explore the effect of the nanoparticle size on drug delivery. JO146-loaded nanoparticles of three different sizes (90, 150, and 220 nm) were formulated with uniform particle size distribution and drug encapsulation efficiency of up to 25%. In in vitro microdilution inhibition assays, 90 nm nanoparticles improved the minimum bactericidal concentration of JO146 two-fold against H. pylori compared to the free drug alone, highlighting that controlled engineering of nanoparticle size is important in drug delivery optimization.

Presence of Helicobacter Species in Gastric Mucosa of Human Patients and Outcome of Helicobacter Eradication Treatment

The genus Helicobacter is composed of bacteria that colonize both the human and animal gastrointestinal tract. Helicobacter pylori infects half of the world’s population, causing various disorders, such as gastritis, duodenitis and gastric cancer. Additionally, non-Helicobacter pylori Helicobacter species (NHPH) are commonly found in the stomach of pigs, dogs and cats. Most of these species have zoonotic potential and prevalence rates of 0.2–6.0%, and have been described in human patients suffering from gastric disorders undergoing a gastric biopsy. The aim of this study was to determine the occurrence of Helicobacter spp. in the stomach of patients with gastric cancer (n = 17) and obese (n = 63) patients. Furthermore, the outcome of the Helicobacter eradication treatment and the current infection status was evaluated. Overall, based on the genus-specific PCR followed by sequencing, DNA from Helicobacter spp. was detected in 46.3% of the patients, including single infections with H. pylori in 43.8% of the patients and mixed infections with H. pylori and canine- or feline-associated H. felis in 2.5%. About 32.5% of the patients had been subjected to previous Helicobacter eradication therapy and the triple standard therapy was the most frequent scheme (42.3%). In 48.0% of the patients who received eradication treatment, bacteria were still detected, including one mixed infection. In 23.1% of the patients who reported that a subsequent test had been performed to confirm the elimination of the bacteria, Helicobacter were still detected. In conclusion, although in a smaller percentage, NHPH may also be present in the human stomach. Thus, specific NHPH screening should be included in the diagnostic routine. The continued presence of H. pylori in the stomach of patients recently subjected to eradication schemes raises questions about the efficacy of the current Helicobacter treatments.

Enhanced enzymatic production of cholesteryl 6'-acylglucoside impairs lysosomal degradation for the intracellular survival of Helicobacter pylori

Background

During autophagy defense against invading microbes, certain lipid types are indispensable for generating specialized membrane-bound organelles. The lipid composition of autophagosomes remains obscure, as does the issue of how specific lipids and lipid-associated enzymes participate in autophagosome formation and maturation. Helicobacter pylori is auxotrophic for cholesterol and converts cholesterol to cholesteryl glucoside derivatives, including cholesteryl 6ʹ-O-acyl-α-d-glucoside (CAG). We investigated how CAG and its biosynthetic acyltransferase assist H. pylori to escape host-cell autophagy.

Methods

We applied a metabolite-tagging method to obtain fluorophore-containing cholesteryl glucosides that were utilized to understand their intracellular locations. H. pylori 26695 and a cholesteryl glucosyltransferase (CGT)-deletion mutant (ΔCGT) were used as the standard strain and the negative control that contains no cholesterol-derived metabolites, respectively. Bacterial internalization and several autophagy-related assays were conducted to unravel the possible mechanism that H. pylori develops to hijack the host-cell autophagy response. Subcellular fractions of H. pylori-infected AGS cells were obtained and measured for the acyltransferase activity.

Results

The imaging studies of fluorophore-labeled cholesteryl glucosides pinpointed their intracellular localization in AGS cells. The result indicated that CAG enhances the internalization of H. pylori in AGS cells. Particularly, CAG, instead of CG and CPG, is able to augment the autophagy response induced by H. pylori. How CAG participates in the autophagy process is multifaceted. CAG was found to intervene in the degradation of autophagosomes and reduce lysosomal biogenesis, supporting the idea that intracellular H. pylori is harbored by autophago-lysosomes in favor of the bacterial survival. Furthermore, we performed the enzyme activity assay of subcellular fractions of H. pylori-infected AGS cells. The analysis showed that the acyltransferase is mainly distributed in autophago-lysosomal compartments.

Conclusions

Our results support the idea that the acyltransferase is mainly distributed in the subcellular compartment consisting of autophagosomes, late endosomes, and lysosomes, in which the acidic environment is beneficial for the maximal acyltransferase activity. The resulting elevated level of CAG can facilitate bacterial internalization, interfere with the autophagy flux, and causes reduced lysosomal biogenesis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12929-021-00768-w.

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.

Temperatures Outside the Optimal Range for Helicobacter pylori Increase Its Harboring within Candida Yeast Cells

Simple Summary

Helicobacter pylori is associated with the development of diverse gastric pathologies. This bacterium has been shown to invade yeast to protect itself from environmental factors such as changes in pH, the presence of antibiotics or variations in nutrients that affect their viability. However, intra-yeast H. pylori has been reported from other sources, including food, or when the storage temperature is outside the optimal growth range for H. pylori, which is 30–37 °C. It is necessary to continue investigating the environmental factors that participate in the entry of the bacteria into yeast. In this work, it was evaluated whether temperature changes promote the entry of H. pylori into Candida and whether this endosymbiosis favors bacterial viability. It was observed that H. pylori significantly increased its invasiveness to yeast when these two microorganisms were co-cultured under 40 °C. The results support that H. pylori invades yeasts to protect itself from stressful environments, favoring its viability in these environments. In addition, it can be suggested that this microorganism would use yeast as a transmission vehicle, thereby contributing to its dissemination in the population. However, the latter still needs to be confirmed.

Abstract

Helicobacter pylori is capable of entering into yeast, but the factors driving this endosymbiosis remain unknown. This work aimed to determine if temperatures outside the optimal range for H. pylori increase its harboring within Candida. H. pylori strains were co-cultured with Candida strains in Brucella broth supplemented with 5% fetal bovine serum and incubated at 4, 25, 37 or 40 °C. After co-culturing, yeasts containing bacteria-like bodies (Y-BLBs) were observed by optical microscopy, and the bacterium were identified as H. pylori by FISH. The H. pylori 16S rRNA gene was amplified from the total DNA of Y-BLBs. The viability of intra-yeast H. pylori cells was confirmed using a viability assay. All H. pylori strains were capable of entering into all Candida strains assayed. The higher percentages of Y-BLBs are obtained at 40 °C with any of the Candida strains. H pylori also increased its harboring within yeast in co-cultures incubated at 25 °C when compared to those incubated at 37 °C. In conclusion, although H. pylori grew significantly at 40 °C, this temperature increased its harboring within Candida. The endosymbiosis between both microorganisms is strain-dependent and permits bacterial cells to remain viable under the stressing environmental conditions assayed.

Autophagy in Gastric Mucosa: The Dual Role and Potential Therapeutic Target

The incidence of stomach diseases is very high, which has a significant impact on human health. Damaged gastric mucosa is more vulnerable to injury, leading to bleeding and perforation, which eventually aggravates the primary disease. Therefore, the protection of gastric mucosa is crucial. However, existing drugs that protect gastric mucosa can cause nonnegligible side effects, such as hepatic inflammation, nephritis, hypoacidity, impotence, osteoporotic bone fracture, and hypergastrinemia. Autophagy, as a major intracellular lysosome-dependent degradation process, plays a key role in maintaining intracellular homeostasis and resisting environmental pressure, which may be a potential therapeutic target for protecting gastric mucosa. Recent studies have demonstrated that autophagy played a dual role when gastric mucosa exposed to biological and chemical factors. More indepth studies are needed on the protective effect of autophagy in gastric mucosa. In this review, we focus on the mechanisms and the dual role of various biological and chemical factors regulating autophagy, such as Helicobacter pylori, virus, and nonsteroidal anti-inflammatory drugs. And we summarize the pathophysiological properties and pharmacological strategies for the protection of gastric mucosa through autophagy.

Does Helicobacter pylori infection affect the structure of bacteria in the gastric mucosa and fluid in patients with chronic antral gastritis?

This study aimed to evaluate the composition of the gastric microbiota in the gastric mucosa and gastric fluid of patients with chronic antral gastritis. Specifically, we sought to determine whether Helicobacter pylori (Hp) infection changes the bacterial community in the gastric mucosa or alters the microbiota in the gastric fluid. The bacterial community at another site in the stomach was also investigated. DNA was extracted from 160 samples collected from 40 patients with chronic antral gastritis (20 Hp-positive and 20 Hp-negative cases). Three tissue samples of the gastric mucosa (gastric angle, body, and antral mucosa) and one tube of gastric fluid were collected from every patient. A 16S rRNA amplification library was created, and high-throughput sequencing was performed. A profile of the community composition was obtained using bioinformatics methods, including cluster, taxonomy, and diversity analyses. Analysis of the gastric bacterial community revealed that the community compositions of the gastric mucosa and gastric fluid of patients without Hp are similar to but show differences from those of Hp-positive patients. The microbiota in Hp-positive patients exhibited reduced microbial diversity, and the gastric fluid of these patients contained a small proportion of Hp. The richness of Leptotrichia in mucosal samples was greater than that in gastric fluid samples from Hp-negative patients with chronic antral gastritis. Hp changes the growth of other microbiota in the mucosa and affects the microbiota in the gastric fluid of patients with chronic antral gastritis. In addition to Hp, the presence of other bacteria might be related to the development of chronic antral gastritis.

The selective advantage of facultative anaerobes relies on their unique ability to cope with changing oxygen levels during infection

Bacteria, including those that are pathogenic, have been generally classified according to their ability to survive and grow in the presence or absence of oxygen: aerobic and anaerobic bacteria, respectively. Strict aerobes require oxygen to grow (e.g., Neisseria), and strict anaerobes grow exclusively without, and do not survive oxygen exposure (e.g., Clostridia); aerotolerant bacteria (e.g., Lactobacilli) are insensitive to oxygen exposure. Facultative anaerobes (e.g., E. coli) have the unique ability to grow in the presence or in the absence of oxygen and are thus well-adapted to these changing conditions, which may constitute an underestimated selective advantage for infection. In the WHO antibiotic-resistant 'priority pathogens' list, facultative anaerobes are overrepresented (8 among 12 listed pathogens), consistent with clinical studies performed in populations particularly susceptible to infectious diseases. Bacteria aerobic respiratory chain plays a central role in oxygen consumption, leading to the formation of hypoxic infectious sites (infectious hypoxia). Facultative anaerobes have developed a wide diversity of aerotolerance and anaerotolerance strategies in vivo. However, at a single cell level, the modulation of the intracellular oxygen level in host infected cells remains elusive and will be discussed in this review. In conclusion, the ability of facultative bacteria to evolve in the presence or the absence of oxygen is essential for their virulence strategy and constitute a selective advantage. TAKE AWAY: Most life-threatening pathogenic bacteria are facultative anaerobes. Only facultative anaerobes are aerotolerant, anaerotolerant and capable of consuming O₂ . Facultative anaerobes induce and are well adapted to cellular hypoxia.

Helicobacter pylori: preying on SIVA for survival in the stomach

Infection with the Gram-negative bacterium Helicobacter pylori remains the most important modifiable risk factor for the development of gastric cancer, a leading cause of cancer-related deaths worldwide. How the interactions between H. pylori and its host shape the gastric environment during chronic infection warrants further investigation. In this issue of the JCI, Palrasu et al. used human cell lines and mouse models to provide mechanistic insight into H. pylori's ability to delay apoptosis in gastric epithelial cells by actively driving the degradation of a proapoptotic factor, SIVA1. Their findings suggest that promoting the survival of gastric epithelial cells has implications not only for H. pylori pathogenesis but for host tumorigenesis.

Intracellular Presence of Helicobacter pylori and Its Virulence-Associated Genotypes within the Vaginal Yeast of Term Pregnant Women

BACKGROUND

Helicobacter pylori transmission routes are not entirely elucidated. Since yeasts are postulated to transmit this pathogen, this study aimed to detect and genotype intracellular H. pylori harbored within vaginal yeast cells.

METHODS

A questionnaire was used to determine risk factors of H. pylori infection. Samples were seeded on Sabouraud Dextrose Agar and horse blood-supplemented Columbia agar. Isolated yeasts were identified using and observed by optical microscopy searching for intra-yeast H. pylori. Total yeast DNA, from one random sample, was extracted to search for H. pylori virulence genes by PCR and bacterial identification by sequencing.

RESULTS

43% of samples contained yeasts, mainly Candida albicans (91%). Microscopy detected bacteria such as bodies and anti-H. pylori antibodies binding particles in 50% of the isolated yeasts. Total DNA extracted showed that 50% of the isolated yeasts were positive for H. pylori 16S rDNA and the sequence showed 99.8% similarity with H. pylori. In total, 32% of H. pylori DNA positive samples were cagA+ vacAs1a vacAm1 dupA-. No relationship was observed between possible H. pylori infection risk factors and vaginal yeasts harboring this bacterium.

CONCLUSION

H. pylori having virulent genotypes were detected within vaginal yeasts constituting a risk for vertical transmission of this pathogen.

Helicobacter pylori: A Review of Current Diagnostic and Management Strategies

As one of the most prevalent infections globally, Helicobacter pylori (H. pylori) continues to present diagnostic and therapeutic challenges for clinicians worldwide. Diagnostically, the "test-and-treat" strategy is the recommended approach for healthcare practitioners when managing this potentially curable disease. The choice of testing method should be based on several factors including patient age, presenting symptoms, and medication use, as well as test reliability, availability, and cost. With rising antibiotic resistance, particularly of macrolides, care must be taken to ensure that therapy is selected based on regional resistance patterns and prior antibiotic exposure. In the USA, macrolide antibiotic resistance rates in some areas have reached or exceeded a generally accepted threshold, such that clarithromycin triple therapy may no longer be an appropriate first-line empiric treatment. Instead, bismuth quadruple therapy should be considered, while levofloxacin-based or alternative macrolide-containing therapies are also options. Once treated, it is essential to test for eradication as untreated H. pylori is associated with serious complications including peptic ulcer disease, mucosa-associated lymphoid tissue lymphoma, and gastric cancer. This review article aims to consolidate current knowledge of H. pylori infection with a particular emphasis on diagnostic and treatment strategies.

Apparent intracellular Helicobacter pylori detected by immunohistochemistry - the missing link in eradication failure

BACKGROUND

Helicobacter (H.) pylori is primarily an extracellularly living bacterium. However, seemingly intracellular occurrence can often be detected by immunohistochemical stains. Considering antimicrobial resistance, we investigated the impact of the apparent intracellular H. pylori (aiHp) on treatment failure of first-line triple therapies.

METHODS

Gastric biopsies of 814 H. pylori infected patients naïve for treatment were analyzed before and after eradication therapy by immunohistochemistry. Thereof, 373 received treatment consisting of amoxicillin, clarithromycin and PPI (AC/PPI). Availability of PCR-based clarithromycin susceptibility test results from pre-treatment gastric biopsies was a pre-condition for matching 52 aiHp to 52 non-aiHp cases within the AC/PPI-group.

RESULTS

AiHp were detected mostly in low counts predominantly in corpus, rarely in antrum biopsies (95.2% vs. 24.6%); they were found in 497 (61%) of all patients and in 192 of 373 patients (51.5%) in the AC/PPI-group. The eradication rate in aiHp vs. non-aiHp cases was 44.4% vs. 72.9% in the entire sample and 45.3% vs. 66.8% in the AC/PPI-group. Among the 104 paired patients, respective values were 46.2% vs. 78.8%; in clarithromycin susceptible cases 60.6% vs. 91.9%. Both aiHp and resistance to clarithromycin proved to be highly significant (p≤0.001) and independent predictors of eradication failure. Twelve of 13 aiHp cases with a clarithromycin sensitive strain, who failed eradication, developed resistance to the antibiotic.

CONCLUSIONS

AiHp found by immunohistochemical staining especially in corpus biopsies proved to be a risk factor for failure of first-line triple therapies; occurrence of aiHp should be considered with regard to therapy options.

Type IV secretion of Helicobacter pylori CagA into oral epithelial cells is prevented by the absence of CEACAM receptor expression

Background

Helicobacter pylori typically colonizes the human stomach, but it can occasionally be detected in the oral cavity of infected persons. Clinical outcome as a result of gastric colonization depends on presence of the pathogenicity island cagPAI that encodes a type-IV secretion system (T4SS) for translocation of the effector protein CagA and ADP-heptose. Upon injection into target cells, CagA is phosphorylated, which can be demonstrated by in vitro infection of the gastric epithelial cell line AGS, resulting in cell elongation. Here we investigated whether H. pylori can exert these responses during interaction with cells from the oral epithelium. To this purpose, three oral epithelial cell lines, HN, CAL-27 and BHY, were infected with various virulent wild-type H. pylori strains, and CagA delivery and ADP-heptose-mediated pro-inflammatory responses were monitored.

Results

All three oral cell lines were resistant to elongation upon infection, despite similar bacterial binding capabilities. Moreover, T4SS-dependent CagA injection was absent. Resistance to CagA delivery was shown to be due to absence of CEACAM expression in these cell lines, while these surface molecules have recently been recognized as H. pylori T4SS receptors. Lack of CEACAM expression in HN, CAL-27 and BHY cells was overcome by genetic introduction of either CEACAM1, CEACAM5, or CEACAM6, which in each of the cell lines was proven sufficient to facilitate CagA delivery and phosphorylation upon H. pylori infection to levels similar to those observed with the gastric AGS cells. Pro-inflammatory responses, as measured by interleukin-8 ELISA, were induced to high levels in each cell line and CEACAM-independent.

Conclusions

These results show that lack of CEACAM receptors on the surface of the oral epithelial cells was responsible for resistance to H. pylori CagA-dependent pathogenic activities, and confirms the important role for the T4SS-dependent interaction of these receptors with H. pylori in the gastric epithelium.

Exofacial phospholipids at the plasma membrane: ill-defined targets for early infection processes

The eukaryotic plasma membrane (PM) consists largely of phospholipids and proteins, and separates the intracellular compartments from the extracellular space. It also serves as a signaling platform for cell-to-cell communication and an interaction platform for the molecular crosstalk between pathogens and their target cells. Much research has been done to elucidate the interactions between pathogens and host membrane proteins. However, little is known about the interactions between pathogens and membrane phospholipids, although reports have described a contribution of phospholipids to cell recognition and/or invasion during early infection by diverse pathogens. Thus, during adhesion to the host cell, the obligate intracellular bacterial pathogens Chlamydia spp., the facultative intracellular pathogen Helicobacter pylori and the facultative aerobic pathogen Vibrio parahaemolyticus, interact with exofacial phospholipids. This review focuses on several prominent instances of pathogen interaction with host-cell phospholipids.

Cellular evasion strategies of Helicobacter pylori in regulating its intracellular fate

Helicobacter pylori colonizes human stomach mucosa and its infection causes gastrointestinal diseases with variable severity. Bacterial infection stimulates autophagy, which is a part of innate immunity used to eliminate intracellular pathogens. Several intracellular bacteria have evolved multipronged strategies to circumvent this conserved system and thereby enhance their chance of intracellular survival. Nonetheless, studies on H. pylori have produced inconsistent results, showing either elevated or reduced clearance efficiency of intracellular bacteria through autophagy. In this review, we summarize recent studies on the mechanisms involved in autophagy induced by H. pylori and the fate of intracellular bacteria.

Mechanisms of persistence, innate immune activation and immunomodulation by the gastric pathogen Helicobacter pylori

The gastric bacterium Helicobacter pylori efficiently evades innate immune detection and persistently colonizes its human host. Understanding the genetic determinants that H. pylori uses to establish and maintain persistence, along with their cellular targets, is key to our understanding of the pathogenesis of this extraordinarily successful bacterial colonizer of the human stomach. This review highlights recent advances in elucidating innate immune recognition of H. pylori, its interactions with myeloid cells and the consequences that this very local infection has for immune responses at extragastric sites in models of allergy, autoimmunity and parasitic infection. The human-specific, gram-negative gastric colonizer and carcinogen H. pylori represents the prototype of a persistent bacterial pathogen. It is transmitted during early childhood, typically from mother to infant, and is believed to persist in its human host from the cradle to the grave. The tremendous success of H. pylori in infecting and colonizing half of the world's population, and in continuously accompanying humans since they migrated out of Africa over 60000 years ago, can largely be attributed to its ability to manipulate the host immune system to its own advantage, and to thereby ensure its own persistence and chronicity. In his final years as an active PI, Stanley Falkow increasingly recognized the need to understand bacterial persistence strategies as a prerequisite of understanding the pathogenesis of chronic bacterial infections, and, inspired in large part by Denise Monack's work on Salmonella persistence, many of our discussions at the time revolved around this topic. Multiple labs have since made important contributions to our understanding of innate immune detection of H. pylori, the types and polarization of adaptive immune responses that ensue, the ability of H. pylori to skew such immune responses to its advantage, and its ability to manipulate the host immune system with far-reaching, even systemic consequences. This review attempts to cover some of these topics, with a particular focus on the most recent contributions by researchers in the field.

Activity and Functional Importance of Helicobacter pylori Virulence Factors

Helicobacter pylori is a very successful Gram-negative pathogen colonizing the stomach of humans worldwide. Infections with this bacterium can generate pathologies ranging from chronic gastritis and peptic ulceration to gastric cancer. The best characterized H. pylori virulence factors that cause direct cell damage include an effector protein encoded by the cytotoxin-associated gene A (CagA), a type IV secretion system (T4SS) encoded in the cag-pathogenicity island (cag PAI), vacuolating cytotoxin A (VacA), γ-glutamyl transpeptidase (GGT), high temperature requirement A (HtrA, a serine protease) and cholesterol glycosyl-transferase (CGT). Since these H. pylori factors are either surface-exposed, secreted or translocated, they can directly interact with host cell molecules and are able to hijack cellular functions. Studies on these bacterial factors have progressed substantially in recent years. Here, we review the current status in the characterization of signaling cascades by these factors in vivo and in vitro, which comprise the disruption of cell-to-cell junctions, induction of membrane rearrangements, cytoskeletal dynamics, proliferative, pro-inflammatory, as well as, pro-apoptotic and anti-apoptotic responses or immune evasion. The impact of these signal transduction modules in the pathogenesis of H. pylori infections is discussed.

Helicobacter pylori inhibited cell proliferation in human periodontal ligament fibroblasts through the Cdc25C/CDK1/cyclinB1 signaling cascade

Purpose

Several studies have shown that the oral cavity is a secondary location for Helicobacter pylori colonization and that H. pylori is associated with the severity of periodontitis. This study investigated whether H. pylori had an effect on the periodontium. We established an invasion model of a standard strain of H. pylori in human periodontal ligament fibroblasts (hPDLFs), and evaluated the effects of H. pylori on cell proliferation and cell cycle progression.

Methods

Different concentrations of H. pylori were used to infect hPDLFs, with 6 hours of co-culture. The multiplicity of infection in the low- and high-concentration groups was 10:1 and 100:1, respectively. The Cell Counting Kit-8 method and Ki-67 immunofluorescence were used to detect cell proliferation. Flow cytometry, quantitative real-time polymerase chain reaction, and western blots were used to detect cell cycle progression. In the high-concentration group, the invasion of H. pylori was observed by transmission electron microscopy.

Results

It was found that H. pylori invaded the fibroblasts, with cytoplasmic localization. Analyses of cell proliferation and flow cytometry showed that H. pylori inhibited the proliferation of periodontal fibroblasts by causing G2 phase arrest. The inhibition of proliferation and G2 phase arrest were more obvious in the high-concentration group. In the low-concentration group, the G2 phase regulatory factors cyclin dependent kinase 1 (CDK1) and cell division cycle 25C (Cdc25C) were upregulated, while cyclin B1 was inhibited. However, in the high-concentration group, cyclin B1 was upregulated and CDK1 was inhibited. Furthermore, the deactivated states of tyrosine phosphorylation of CDK1 (CDK1-Y15) and serine phosphorylation of Cdc25C (Cdc25C-S216) were upregulated after H. pylori infection.

Conclusions

In our model, H. pylori inhibited the proliferation of hPDLFs and exerted an invasive effect, causing G2 phase arrest via the Cdc25C/CDK1/cyclin B1 signaling cascade. Its inhibitory effect on proliferation was stronger in the high-concentration group.

A Deep Learning Convolutional Neural Network Can Recognize Common Patterns of Injury in Gastric Pathology

CONTEXT.—

Most deep learning (DL) studies have focused on neoplastic pathology, with the realm of inflammatory pathology remaining largely untouched.

OBJECTIVE.—

To investigate the use of DL for nonneoplastic gastric biopsies.

DESIGN.—

Gold standard diagnoses were blindly established by 2 gastrointestinal pathologists. For phase 1, 300 classic cases (100 normal, 100 Helicobacter pylori, 100 reactive gastropathy) that best displayed the desired pathology were scanned and annotated for DL analysis. A total of 70% of the cases for each group were selected for the training set, and 30% were included in the test set. The software assigned colored labels to the test biopsies, which corresponded to the area of the tissue assigned a diagnosis by the DL algorithm, termed area distribution (AD). For Phase 2, an additional 106 consecutive nonclassical gastric biopsies from our archives were tested in the same fashion.

RESULTS.—

For Phase 1, receiver operating curves showed near perfect agreement with the gold standard diagnoses at an AD percentage cutoff of 50% for normal (area under the curve [AUC] = 99.7%) and H pylori (AUC = 100%), and 40% for reactive gastropathy (AUC = 99.9%). Sensitivity/specificity pairings were as follows: normal (96.7%, 86.7%), H pylori (100%, 98.3%), and reactive gastropathy (96.7%, 96.7%). For phase 2, receiver operating curves were slightly less discriminatory, with optimal AD cutoffs reduced to 40% across diagnostic groups. The AUCs were 91.9% for normal, 100% for H pylori, and 94.0% for reactive gastropathy. Sensitivity/specificity parings were as follows: normal (73.7%, 79.6%), H pylori (95.7%, 100%), reactive gastropathy (100%, 62.5%).

CONCLUSIONS.—

A convolutional neural network can serve as an effective screening tool/diagnostic aid for H pylori gastritis.

Dietary Resistant Potato Starch Alters Intestinal Microbial Communities and Their Metabolites, and Markers of Immune Regulation and Barrier Function in Swine

Interactions between diet, the microbiota, and the host set the ecological conditions in the gut and have broad implications for health. Prebiotics are dietary compounds that may shift conditions toward health by promoting the growth of beneficial microbes that produce metabolites capable of modulating host cells. This study's objective was to assess how a dietary prebiotic could impact host tissues via modulation of the intestinal microbiota. Pigs fed a diet amended with 5% resistant potato starch (RPS) exhibited alterations associated with gut health relative to swine fed an unamended control diet (CON). RPS intake increased abundances of anaerobic Clostridia in feces and several tissues, as well as intestinal concentrations of butyrate. Functional gene amplicons suggested bacteria similar to Anaerostipes hadrus were stimulated by RPS intake. The CON treatment exhibited increased abundances of several genera of Proteobacteria (which utilize respiratory metabolisms) in several intestinal locations. RPS intake increased the abundance of regulatory T cells in the cecum, but not periphery, and cecal immune status alterations were indicative of enhanced mucosal defenses. A network analysis of host and microbial changes in the cecum revealed that regulatory T cells positively correlated with butyrate concentration, luminal IgA concentration, expression of IL-6 and DEF1B, and several mucosa-associated bacterial taxa. Thus, the administration of RPS modulated the microbiota and host immune status, altering markers of cecal barrier function and immunological tolerance, and suggesting a reduced niche for bacterial respiration.

A Novel Role for Helicobacter pylori Gamma-Glutamyltranspeptidase in Regulating Autophagy and Bacterial Internalization in Human Gastric Cells

The risk of developing gastric cancer is strongly linked to Helicobacter pylori (H. pylori) infection. Alternatively, autophagy is a conserved response that is important in cellular homeostasis and provides protection against bacterial infections. Although H. pylori is typically considered an extracellular bacterium, several reports indicate that it internalizes, possibly to avoid exposure to antibiotics. Mechanisms by which H. pylori manipulates host cell autophagic processes remain unclear and, importantly, none of the available studies consider a role for the secreted H. pylori virulence factor gamma-glutamyltranspeptidase (HpGGT) in this context. Here, we identify HpGGT as a novel autophagy inhibitor in gastric cells. Our experiments revealed that deletion of HpGGT increased autophagic flux following H. pylori infection of AGS and GES-1 gastric cells. In AGS cells, HpGGT disrupted the late stages of autophagy by preventing degradation in lysosomes without affecting lysosomal acidification. Specifically, HpGGT impaired autophagic flux by disrupting lysosomal membrane integrity, which leads to a decrease in lysosomal cathepsin B activity. Moreover, HpGGT was necessary for efficient internalization of the bacteria into gastric cells. This important role of HpGGT in internalization together with the ability to inhibit autophagy posits HpGGT as a key virulence factor in the development of gastric cancer.

VacA generates a protective intracellular reservoir for Helicobacter pylori that is eliminated by activation of the lysosomal calcium channel TRPML1

Helicobacter pylori infection is a proven carcinogen for gastric cancer. Its virulence factor vacuolating cytotoxin A (VacA) promotes more severe disease and gastric colonization. VacA, by an unknown mechanism, usurps lysosomal and autophagy pathways to generate a protected reservoir for H. pylori that confers bacterial survival in vitro. Here, we show the existence of a VacA-generated intracellular niche in vivo that protects the bacteria from antibiotic treatment and leads to infection recrudescence after therapy. Furthermore, we report that VacA targets the lysosomal calcium channel TRPML1 to disrupt endolysosomal trafficking and mediate these effects. Remarkably, H. pylori that lack toxigenic VacA colonize enlarged dysfunctional lysosomes in the gastric epithelium of trpml1-null mice, where they are protected from eradication therapy. Furthermore, a small molecule agonist directed against TRPML1 reversed the toxic effects of VacA on endolysosomal trafficking, culminating in the clearance of intracellular bacteria. These results suggest that TRPML1 may represent a therapeutic target for chronic H. pylori infection.

Protein changes in gastric epithelial cells RGM-1 in response to Helicobacter pylori infection

Helicobacter pylori-induced inflammation significantly increases the risk of gastric cancer. To investigate the role of H. pylori infection in gastric epithelial cell carcinogenesis, flow cytometry was used to analyze the apoptosis of gastric epithelial cells infected by H. pylori. Next, LTQ MS mass spectrometry (MS) was applied to identify protein changes in gastric epithelial cells infected with H. pylori, and then bioinformatics was adopted to analyze the cellular localization and biological function of differential proteins. LTQ MS/MS successfully identified identified 22 differential proteins successfully, including 20 host-cell proteins and two H. pylori bacterial proteins. Also, human proteins were located in all areas of cells and involved in various cell biological functions. The oncogene proteins p53, p16, and C-erbB-2 proteins in H. pylori-infected RGM-1 cells were remarkably increased from the analysis by Western blot analysis. H. pylori infection of gastric epithelial cells leads to changes in various protein components in the cell, and enhances the expression of oncogene proteins, thereby increasing the possibility of possibility of carcinogenesis of H. pylori infection.

Sequestration inside the yeast vacuole may enhance Helicobacter pylori survival against stressful condition

Vacuole of eukaryotic cells, beyond intracellular digestion plays additional roles such as storage of nutrients that provide favorable conditions for bacterial survival. In this study, occurrence of H. pylori inside the vacuole of Candida yeast was studied and the role of vacuolating cytotoxin A (VacA) in constructing the vacuole was discussed. One gastric Candida yeast was used for Live/Dead stain and fluorescence in situ hybridization (FISH) with universal bacterial probe. Yeast total DNA was used for amplification of full-length bacterial 16S rDNA as well as H. pylori-specific 16S rDNA and vacA alleles. Vacuoles were isolated from yeast cells and stained with fluorescent yeast vacuole membrane marker MDY-64. DNA extracted from vacuoles was used for amplification of H. pylori-specific 16S rDNA. Fluorescent microscopy showed occurrence of viable bacteria inside the vacuole of intact Candida yeast cells. FISH showed intracellular bacteria as fluorescent spots inside the vacuole of mother and daughter yeast cells, suggesting bacterial transmission to next generations of yeast. Sequencing of amplified products of bacterial 16S rDNA and amplification of H. pylori 16S rDNA and vacA confirmed the identity of intracellular bacteria as H. pylori. Isolated vacuoles were stained with membrane-specific marker and H. pylori 16S rDNA was amplified from their DNA content. Results of this study suggest yeast vacuole as a specialized niche for H. pylori. It appears that sequestration inside the vacuole may enhance bacterial survival.

Pathogenicity of Helicobacter pylori in cancer development and impacts of vaccination

Helicobacter pylori affect around 50% of the population worldwide. More importantly, the gastric infection induced by this bacterium is deemed to be associated with the progression of distal gastric carcinoma and gastric mucosal lymphoma in the human. H. pylori infection and its prevalent genotype significantly differ across various geographical regions. Based on numerous virulence factors, H. pylori can target different cellular proteins to modulate the variety of inflammatory responses and initiate numerous "hits" on the gastric mucosa. Such reactions lead to serious complications, including gastritis and peptic ulceration, gastric cancer and gastric mucosa-associated lymphoid structure lymphoma. Therefore, H. pylori have been considered as the type I carcinogen by the Global Firm for Research on Cancer. During the two past decades, different reports revealed that H. pylori possess oncogenic potentials in the gastric mucosa through a complicated interplay between the bacterial factors, various facets, and the environmental factors. Accordingly, numerous signaling pathways could be triggered in the development of gastrointestinal diseases (e.g., gastric cancer). Therefore, the main strategy for the treatment of gastric cancer is controlling the disease far before its onset using preventive/curative vaccination. Increasing the efficiency of vaccines may be achieved by new trials of vaccine modalities, which is used to optimize the cellular immunity. Taken all, H. pylori infection may impose severe complications, for resolving of which extensive researches are essential in terms of immune responses to H. pylori. We envision that H. pylori-mediated diseases can be controlled by advanced vaccines and immunotherapies.

Effective antimicrobial activity of rifabutin against multidrug-resistant Helicobacter pylori

BACKGROUND

Helicobacter pylori resistance to more than one antibiotic is the main reason for failure in bacterial eradication in a considerable number of patients. Rifabutin (RFB) with a broad-spectrum of antimicrobial therapy has been suggested for treatment of refractory multidrug-resistant infections.

METHODS

Helicobacter pylori isolates from 104 patients were examined for resistance to 5 currently used antibiotics and RFB, using agar dilution method. Twofold serial dilutions of antibiotics were used and MICs (μg/mL) determined as metronidazole (MTZ 8), clarithromycin (CLR 2), amoxicillin (AMX 1), tetracycline (TET 0.5), furazolidone (FRZ 0.5), and RFB (0.06).

RESULTS

Of 104 H. pylori isolates, only 7 (6.7%) were sensitive to all the 6 antibiotics. However, 30 (28.8%) were resistant to one antibiotic, 28 (26.9%) to two, 19 (18.2%) to three, 14 (13.4%) to four, and 6 (5.7%) to five currently used antibiotics. Overall, 67(64.4%) of isolates were resistant to 2-5 currently used antibiotics and considered as multidrug-resistant (MDR), with 59 (88.1%) showing sensitivity to RFB and 8 (11.9%) resistance (P < 0.05). Of 33 isolates resistant to both MTZ and CLR, 25 (75.7%) were sensitive to RFB and 8 (24.3%) resistant (P < 0.05).

DISCUSSION

In vitro antimicrobial effectiveness of RFB on MDR H. pylori including those with resistance to both MTZ and CLR was demonstrated. However, RFB efficacy decreased as the number of antibiotics responsible for MDR increased. Considering that RFB inhibits both extra- and intracellular H. pylori, it can be suggested as an effective antibiotic against of MDR H. pylori.

Helicobacter pylori cholesterol glucosylation modulates autophagy for increasing intracellular survival in macrophages

Cholesterol-α-glucosyltransferase (CGT) encoded by the type 1 capsular polysaccharide biosynthesis protein J (capJ) gene of Helicobacter pylori converts cellular cholesterol into cholesteryl glucosides. H. pylori infection induces autophagy that may increase bacterial survival in epithelial cells. However, the role of H. pylori CGT that exploits lipid rafts in interfering with autophagy for bacterial survival in macrophages has not been investigated. Here, we show that wild-type H. pylori carrying CGT modulates cholesterol to trigger autophagy and restrain autophagosome fusion with lysosomes, permitting a significantly higher bacterial burden in macrophages than that in a capJ-knockout (∆CapJ) mutant. Knockdown of autophagy-related protein 12 impairs autophagosome maturation and decreases the survival of internalised H. pylori in macrophages. These results demonstrate that CGT plays a crucial role in the manipulation of the autophagy process to impair macrophage clearance of H. pylori.

Reduced lysosomal clearance of autophagosomes promotes survival and colonization of Helicobacter pylori

Evasion of autophagy is key for intracellular survival of bacteria in host cells, but its involvement in persistent infection by Helicobacter pylori, a bacterium identified to invade gastric epithelial cells, remains obscure. The aim of this study was to functionally characterize the role of autophagy in H. pylori infection. Autophagy was assayed in H. pylori-infected human gastric epithelium and the functional role of autophagy was determined via genetic or pharmacological ablation of autophagy in mouse and cell line models of H. pylori infection. Here, we showed that H. pylori inhibited lysosomal function and thereby promoted the accumulation of autophagosomes in gastric epithelial cells. Importantly, inhibiting autophagosome formation by pharmacological inhibitors or genetic ablation of BECN1 or ATG5 reduced H. pylori intracellular survival, whereas inhibition of lysosomal functions exerted an opposite effect. Further experiments demonstrated that H. pylori inhibited lysosomal acidification and the retrograde trafficking of mannose-6-phosphate receptors, both of which are known to positively regulate lysosomal function. We conclude that H. pylori subverts autophagy into a pro-survival mechanism through inhibition of lysosomal clearance of autophagosomes. Disruption of autophagosome formation offers a novel strategy to reduce H. pylori colonization in human stomachs. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Repurposing the anthelmintic drug niclosamide to combat Helicobacter pylori

There is an urgent need to discover novel antimicrobial therapies. Drug repurposing can reduce the time and cost risk associated with drug development. We report the inhibitory effects of anthelmintic drugs (niclosamide, oxyclozanide, closantel, rafoxanide) against Helicobacter pylori strain 60190 and pursued further characterization of niclosamide against H. pylori. The MIC of niclosamide against H. pylori was 0.25 μg/mL. Niclosamide was stable in acidic pH and demonstrated partial synergy with metronidazole and proton pump inhibitors, such as omeprazole and pantoprazole. Niclosamide administration at 1 × MIC concentration, eliminated 3-log₁₀ CFU of H. pylori adhesion/invasion to AGS cells. Interestingly, no resistance developed even after exposure of H. pylori bacteria to niclosamide for 30 days. The cytotoxic assay demonstrated that niclosamide is not hemolytic and has an IC₅₀ of 4 μg/mL in hepatic and gastric cell lines. Niclosamide administration decreased transmembrane pH as determined by DiSC₃(5) assay indicating that the mechanism of action of the anti-H. pylori activity of niclosamide was the disruption of H. pylori proton motive force. Niclosamide was effective in the Galleria mellonella-H. pylori infection model (p = 0.0001) and it can be develop further to combat H. pylori infection. However, results need to be confirmed with other H. pylori and clinical strains.

Prediction of Host-Pathogen Interactions for Helicobacter pylori by Interface Mimicry and Implications to Gastric Cancer

There is a strong correlation between some pathogens and certain cancer types. One example is Helicobacter pylori and gastric cancer. Exactly how they contribute to host tumorigenesis is, however, a mystery. Pathogens often interact with the host through proteins. To subvert defense, they may mimic host proteins at the sequence, structure, motif, or interface levels. Interface similarity permits pathogen proteins to compete with those of the host for a target protein and thereby alter the host signaling. Detection of host-pathogen interactions (HPIs) and mapping the re-wired superorganism HPI network-with structural details-can provide unprecedented clues to the underlying mechanisms and help therapeutics. Here, we describe the first computational approach exploiting solely interface mimicry to model potential HPIs. Interface mimicry can identify more HPIs than sequence or complete structural similarity since it appears more common than the other mimicry types. We illustrate the usefulness of this concept by modeling HPIs of H. pylori to understand how they modulate host immunity, persist lifelong, and contribute to tumorigenesis. H. pylori proteins interfere with multiple host pathways as they target several host hub proteins. Our results help illuminate the structural basis of resistance to apoptosis, immune evasion, and loss of cell junctions seen in H. pylori-infected host cells.

Antigenic and immunogenic evaluation of Helicobacter pylori FlaA epitopes

Objective(s):

Helicobacter pylori are among most common human pathogens affecting at least half of the world’s population. Mobility is one of the important primary factors in bacterial colonization and invasion. The purpose of this research is cloning, expression, and purification of FlaA protein specific epitopes in order to evaluate their antigenicity and immunogenicity.

Materials and Methods:

The antigenic region of the flaA gene was bioinformatically predicted using Epitope mapping software’s and the predicted epitopes were expressed in a prokaryotic expression vector. The antigen was injected into the animal model (mice BALB/c) and some indicators including IgG1, IgG2a, IgA, IFN-γ, and IL 5 were measured.

Results:

The immunogenicity studies in animal models by measuring serum antibodies (IgG1, IgG2a, and IgA) and cytokines (IFN-γ and IL5) revealed that the rFlaA induces a proper immune response in animal models.

Conclusion:

The recombinant FlaA protein is antigenic and immunogenic. Therefore, it might be used in order to design of specific diagnostic kits and recombinant vaccines against H. pylori.

Oxidative Phosphorylation System in Gastric Carcinomas and Gastritis

Switching of cellular energy production from oxidative phosphorylation (OXPHOS) by mitochondria to aerobic glycolysis occurs in many types of tumors. However, the significance of this switching for the development of gastric carcinoma and what connection it may have to Helicobacter pylori infection of the gut, a primary cause of gastric cancer, are poorly understood. Therefore, we investigated the expression of OXPHOS complexes in two types of human gastric carcinomas ("intestinal" and "diffuse"), bacterial gastritis with and without metaplasia, and chemically induced gastritis by using immunohistochemistry. Furthermore, we analyzed the effect of HP infection on several key mitochondrial proteins. Complex I expression was significantly reduced in intestinal type (but not diffuse) gastric carcinomas compared to adjacent control tissue, and the reduction was independent of HP infection. Significantly, higher complex I and complex II expression was present in large tumors. Furthermore, higher complex II and complex III protein levels were also obvious in grade 3 versus grade 2. No differences of OXPHOS complexes and markers of mitochondrial biogenesis were found between bacterially caused and chemically induced gastritis. Thus, intestinal gastric carcinomas, but not precancerous stages, are frequently characterized by loss of complex I, and this pathophysiology occurs independently of HP infection.

Autophagy-related genes in Helicobacter pylori infection

BACKGROUND

In vitro studies have shown that Helicobacter pylori (H. pylori) infection induces autophagy in gastric epithelial cells. However, prolonged exposure to H. pylori reduces autophagy by preventing maturation of the autolysosome. The alterations of the autophagy-related genes in H. pylori infection are not yet fully understood.

MATERIALS AND METHODS

We analyzed autophagy-related gene expression in H. pylori-infected gastric mucosa compared with uninfected gastric mucosa obtained from 136 Bhutanese volunteers with mild dyspeptic symptoms. We also studied single nucleotide polymorphisms (SNPs) of autophagy-related gene in 283 Bhutanese participants to identify the influence on susceptibility to H. pylori infection.

RESULTS

Microarray analysis of 226 autophagy-related genes showed that 16 genes were upregulated (7%) and nine were downregulated (4%). We used quantitative reverse transcriptase polymerase chain reaction to measure mRNA levels of the downregulated genes (ATG16L1, ATG5, ATG4D, and ATG9A) that were core molecules of autophagy. ATG16L1 and ATG5 mRNA levels in H. pylori-positive specimens (n=86) were significantly less than those in H. pylori-negative specimens (n=50). ATG16L1 mRNA levels were inversely related to H. pylori density. We also compared SNPs of ATG16L1 (rs2241880) among 206 H. pylori-positive and 77 H. pylori-negative subjects. The odds ratio for the presence of H. pylori in the GG genotype was 0.40 (95% CI: 0.18-0.91) relative to the AA/AG genotypes.

CONCLUSIONS

Autophagy-related gene expression profiling using high-throughput microarray analysis indicated that downregulation of core autophagy machinery genes may depress autophagy functions and possibly provide a better intracellular habit for H. pylori in gastric epithelial cells.

Nuclear Glycogen Inclusions in Canine Parietal Cells

Nuclear glycogen inclusions occur infrequently in pathologic conditions but also in normal human and animal tissues. Their function or significance is unclear. To the best of the authors' knowledge, no reports of nuclear glycogen inclusions in canine parietal cells exist. After initial observations of nuclear inclusions/pseudoinclusions during routine histopathology, the authors retrospectively examined samples of gastric mucosa from dogs presenting with gastrointestinal signs for the presence of intranuclear inclusions/pseudoinclusions and determined their composition using histologic and electron-microscopic methods. In 24 of 108 cases (22%), the authors observed various numbers of intranuclear inclusions/pseudoinclusions within scattered parietal cells. Nuclei were characterized by marked karyomegaly and chromatin margination around a central optically empty or slightly eosinophilic area. The intranuclear inclusions/pseudoinclusions stained positive with periodic acid-Schiff (PAS) and were diastase sensitive, consistent with glycogen. Several PAS-positive/diastase-sensitive sections were further examined by transmission electron microscopy, also using periodic acid-thiocarbohydrazide-silver proteinate (PA-TCH-SP) staining to identify polysaccharides. Ultrastructurally, the nuclear inclusions were composed of electron-dense particles that were not membrane bound, without evidence of nuclear membrane invaginations or cytoplasmic organelles in the nuclei, and positive staining with PA-TCH-SP, confirming a glycogen composition. No cytoplasmic glycogen deposits were observed, suggesting that the intranuclear glycogen inclusions were probably synthesized in loco. Nuclear glycogen inclusions were not associated with gastritis or colonization by Helicobacter-like organisms ( P > .05). Our findings suggest that nuclear glycogen inclusions in canine parietal cells could be an incidental finding. Nevertheless, since nuclear glycogen is present in several pathologic conditions, further investigations could be warranted to determine their true significance.

Adhesion and Invasion of Gastric Mucosa Epithelial Cells by Helicobacter pylori

Helicobacter pylori is the main pathogenic bacterium involved in chronic gastritis and peptic ulcer and a class 1 carcinogen in gastric cancer. Current research focuses on the pathogenicity of H. pylori and the mechanism by which it colonizes the gastric mucosa. An increasing number of in vivo and in vitro studies demonstrate that H. pylori can invade and proliferate in epithelial cells, suggesting that this process might play an important role in disease induction, immune escape and chronic infection. Therefore, to explore the process and mechanism of adhesion and invasion of gastric mucosa epithelial cells by H. pylori is particularly important. This review examines the relevant studies and describes evidence regarding the adhesion to and invasion of gastric mucosa epithelial cells by H. pylori.