Life in the human stomach: persistence strategies of the bacterial pathogen Helicobacter pylori

Organoid of ovarian cancer: genomic analysis and drug screening

Ovarian cancer is the most common malignant tumors of the female reproductive system, and its standard treatments are cytoreductive surgery and platinum-based adjuvant chemotherapy. Great advances have been achieved in novel treatment strategies, including targeted therapy and immunotherapy. However, ovarian cancer has the highest mortality rate among gynecological tumors due to therapeutic resistance and the gap between preclinical data and actual clinical efficacy. Organoids are a 3D culture model that markedly affects gene analysis, drug screening, and drug sensitivity determination of tumors, especially when used in targeted therapy and immunotherapy. In addition, organoid can lead to advances in the preclinical research of ovarian cancer due to its convenient cultivation, good genetic stability, and high homology with primary tumors.

Cortactin: A Major Cellular Target of the Gastric Carcinogen Helicobacter pylori

Cortactin is an actin binding protein and actin nucleation promoting factor regulating cytoskeletal rearrangements in nearly all eukaryotic cell types. From this perspective, cortactin poses an attractive target for pathogens to manipulate a given host cell to their own benefit. One of the pathogens following this strategy is Helicobacter pylori, which can cause a variety of gastric diseases and has been shown to be the major risk factor for the onset of gastric cancer. During infection of gastric epithelial cells, H. pylori hijacks the cellular kinase signaling pathways, leading to the disruption of key cell functions. Specifically, by overruling the phosphorylation status of cortactin, H. pylori alternates the activity of molecular interaction partners of this important protein, thereby manipulating the performance of actin-cytoskeletal rearrangements and cell movement. In addition, H. pylori utilizes a unique mechanism to activate focal adhesion kinase, which subsequently prevents host epithelial cells from extensive lifting from the extracellular matrix in order to achieve chronic infection in the human stomach.

Total synthesis of theHelicobacter pyloriserotype O2 O-antigen α-(1 → 2)- and α-(1 → 3)-linked oligoglucosides

Unique α-(1 → 2)- and α-(1 → 3)-linked oligoglucosides from theH. pyloriserotype O2 O-antigen were synthesized with exclusive α-selectivity using remote participation effects.

An enzyme-free electrochemical sandwich DNA assay based on the use of hybridization chain reaction and gold nanoparticles: application to the determination of the DNA of Helicobacter pylori

An ultrasensitive enzyme-free electrochemical sandwich DNA biosensor is described for the detection of ssDNA oligonucleotides. A DNA sequence derived from the genom of Helicobacter pylori was selected as a model target DNA. The DNA assay was realized through catching target DNA on capture DNA immobilized gold electrode; then labeling the target DNA with reporter DNA (rpDNA) and initiator DNA (iDNA) co-modified gold nanoparticles (AuNPs). The high density of iDNAs serves as one of the amplification strategies. The iDNA triggers hybridization chain reaction (HCR) between two hairpins. This leads to the formation of a long dsDNA concatamer strand and represents one amplification strategy. The electrochemical probe [Ru(NH₃)₅L]²⁺, where L stands for 3-(2-phenanthren-9-ylvinyl)pyridine, intercalated into dsDNA chain. Multiple probe molecules intercalate into one dsDNA chain, serving as one amplification strategy. The electrode was subjected to differential pulse voltammetry for signal acquisition, and the oxidation peak current at -0.28 V was recorded. On each AuNP, 240 iDNA and 25 rpDNA molecules were immobilized. Successful execution of HCR at the DNA-modified AuNPs was confirmed by gel electrophoresis and hydrodynamic diameter measurements. Introduction of HCR significantly enhances the DNA detection signal intensity. The assay has two linear ranges of different slopes, one from 0.01 fM to 0.5 fM; and one from 1 fM to 100 fM. The detection limit is as low as 0.68 aM. Single mismatch DNA can be differentiated from the fully complementary DNA. Conceivably, this highly sensitive and selective assay provides a general method for detection of various kinds of DNA. Graphical abstractSchematic representation of the detection and the amplification principles of the electrochemical sandwich DNA assay. Purple curl: Captured DNA; Green curl: Reporter DNA; Orange curl: HCR initiator DNA; Yellow solid-circle: Gold nanoparticle; H1 and H2: Two hairpin DNA; [Ru(NH₃)₅L]²⁺: Signal probe.

Relationship between Helicobacter pylori Infection and Plasmacytoid and Myeloid Dendritic Cells in Peripheral Blood and Gastric Mucosa of Children

PURPOSE

To investigate the frequency and activation status of peripheral plasmacytoid DCs (pDCs) and myeloid DCs (mDCs) as well as gastric mucosa DC subset distribution in Helicobacter pylori- (H. pylori-) infected and noninfected children.

MATERIALS AND METHODS

Thirty-six children were studied; twenty-one had H. pylori. The frequencies of circulating pDCs (lineage-HLA-DR+CD123+) and mDCs (lineage-HLA-DR+CD11c+) and their activation status (CD83, CD86, and HLA-DR expression) were assessed by flow cytometry. Additionally, the densities of CD11c+, CD123+, CD83+, CD86+, and LAMP3+ cells in the gastric mucosa were determined by immunohistochemistry.

RESULTS

The frequency of circulating CD83+ mDCs was higher in H. pylori-infected children than in the noninfected controls. The pDCs demonstrated upregulated HLA-DR surface expression, but no change in CD86 expression. Additionally, the densities of gastric lamina propria CD11c+ cells and epithelial pDCs were increased. There was a significant association between frequency of circulating CD83+ mDCs and gastric lamina propria mDC infiltration.

CONCLUSION

This study shows that although H. pylori-infected children had an increased population of mature mDCs bearing CD83 in the peripheral blood, they lack mature CD83+ mDCs in the gastric mucosa, which may promote tolerance to local antigens rather than immunity. In addition, this may reduce excessive inflammatory activity as reported for children compared to adults.

Helicobacter pylori Stress-Response: Definition of the HrcA Regulon

Bacteria respond to different environmental stresses by reprogramming the transcription of specific genes whose proper expression is critical for their survival. In this regard, the heat-shock response, a widespread protective mechanism, triggers a sudden increase in the cellular concentration of different proteins, including molecular chaperones and proteases, to preserve protein folding and maintain cellular homeostasis. In the medically important gastric pathogen Helicobacter pylori the regulation of the principal heat-shock genes is under the transcriptional control of two repressor proteins named HspR and HrcA. To define the HrcA regulon, we carried out whole transcriptome analysis through RNA-sequencing, comparing the transcriptome of the H. pylori G27 wild type strain to that of the isogenic hrcA-knockout strain. Overall, differential gene expression analysis outlined 49 genes to be deregulated upon hrcA gene inactivation. Interestingly, besides controlling the transcription of genes coding for molecular chaperones and stress-related mediators, HrcA is involved in regulating the expression of proteins whose function is linked to several cellular processes crucial for bacterial survival and virulence. These include cell motility, membrane transporters, Lipopolysaccharide modifiers and adhesins. The role of HrcA as a central regulator of H. pylori transcriptome, as well as its interconnections with the HspR regulon are here analyzed and discussed. As the HrcA protein acts as a pleiotropic regulator, influencing the expression of several stress-unrelated genes, it may be considered a promising target for the design of new antimicrobial strategies.

Gastric microflora and gastric disease

Gastric environment has long been considered sterile, but the discovery of Helicobacter pylori (H. pylori) changed such concept in 1982. Over the past few decades, modern techniques have provided insight into microbial communities in the stomach and the interactions between communities, ranging from methods that rely on bacterial culture to the application of macrogenomics and high-throughput sequencing techniques. H. pylori is an important risk factor for gastric disease, but there may be other bacteria involved in the occurrence of gastric disease. This review summarizes the current progress in the understanding of the relationship between gastric microflora and gastric disease.

Gastric Cancer in the Era of Immune Checkpoint Blockade

Gastric cancer (GC) is one of the most important malignancies worldwide because of its high incidence and mortality. The very low survival rates are mainly related to late diagnosis and limited treatment options. GC is the final clinical outcome of a stepwise process that starts with a chronic and sustained inflammatory reaction mounted in response to Helicobacter pylori infection. The bacterium modulates innate and adaptive immunity presumably as part of the strategies to survive, which favors the creation of an immunosuppressive microenvironment that ultimately facilitates GC progression. T-cell exhaustion, which is characterized by elevated expression of immune checkpoint (IC) proteins, is one of the most salient manifestations of immunosuppressive microenvironments. It has been consistently demonstrated that the tumor-immune microenvironment(TIME)‐exhausted phenotype can be reverted by blocking ICs with monoclonal antibodies. Although these therapies are associated with long-lasting response rates, only a subset of patients derive clinical benefit, which varies according to tumor site. The search for biomarkers to predict the response to IC inhibition is a matter of intense investigation as this may contribute to maximize disease control, reduce side effects, and minimize cost. The approval of pembrolizumab for its use in GC has rocketed immuno-oncology research in this cancer type. In this review, we summarize the current knowledge centered around the immune contexture and recent findings in connection with IC inhibition in GC.

Helicobacter pylori genotypes among Belarus patients with gastroduodenal disorders and their association with clinical outcome

The aim of this study was to evaluate the prevalence of Helicobacter pylori genotypes (vacA and cagPAI) directly in gastric biopsy specimens in patients with gastric diseases in Belarus. Gastric biopsies were collected from 461 patients with different gastrointestinal disorders: superficial gastritis (287 subjects), atrophy gastritis (59 subjects), erosive gastritis (47 subjects), duodenal ulcer disease (54 subjects), and stomach ulcer (14 subjects). PCR-based genotyping was used to detect s1a, s1b, s2, m1a, m1b, m2, cagM, cagA, and cagT genes. Overall prevalence of vacA s1a allele was 60.5% followed by m2 (47.1%) and m1a (37.5%). The analysis of data showed that genotype s1a/m1a was significantly more prevalent in patients with duodenal ulcer (21.4% vs. 45.1%, OR = 3.0, 95% CI = 1.5-6.1). The cagA gene was found with a high incidence in most patients with inflammatory diseases of stomach and duodenum. There was a significant increase in the frequency of cagT in patients with duodenal ulcer as compared to superficial gastritis. A high cagM prevalence was found in patients with atrophy gastritis and duodenal ulcer disease. All three island genes of pathogenicity of cagPAI are more often detected in patients with duodenal ulcer, which increases the risk of developing duodenal ulcer by 4.5 times.

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

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

Helicobacter pylori-downregulated tumor necrosis factor receptor-associated protein 1 mediates apoptosis of human gastric epithelial cells

Heat shock proteins (HSPs) are crucial proteins in maintaining the homeostasis of human gastric epithelial cells. Tumor necrosis factor receptor-associated protein 1 (TRAP1), a member of the HSP90 family, has been shown to be involved in various crucial physiological processes, particularly against apoptosis. However, the regulation and function of TRAP1 in Helicobacter pylori infection is still unknown. Here, we found that TRAP1 expression was downregulated on human gastric epithelial cells during H. pylori infection by real-time polymerase chain reaction (PCR) and western blot analysis. Through virulence factors mutant H. pylori strains infection and inhibitors screening, we found that H. pylori vacuolating cytotoxin A ( vacA), but not cytotoxin-associated gene A ( cagA) protein, induced human gastric epithelial cells to downregulate TRAP1 via P38MAPK pathway by real-time PCR and western blot analysis. Furthermore, downregulation of TRAP1 with lentivirus carrying TRAP1 short hairpin RNA constructs impairs mitochondrial function, and increases apoptosis of gastric epithelial cells. The results indicate that H. pylori vacA downregulated TRAP1 is involved in the regulation of gastric epithelial cell apoptosis.

Long noncoding RNA THAP9-AS1 is induced by Helicobacter pylori and promotes cell growth and migration of gastric cancer

Background

Long noncoding RNAs (LncRNAs) have been confirmed to play crucial roles in cancer biology. Gastric cancer (GC) is the third leading cause of cancer related death, and Helicobacter pylori (H. pylori) is the major risk factor for GC. In this study, we focused on the roles of H. pylori-related lncRNAs in the progression of GC.

Method

Differentially expressed lncRNAs were identified through RNA-seq analysis of H. pylori-infected GC cells.

Results

We found that the expression of the lncRNA THAP9-AS1 was up-regulated after infection of GC cells with H. pylori and was higher in GC tissues than in gastritis tissues. Colony formation, CCK8 and transwell assays were executed to show that THAP9-AS1 can promote GC cell proliferation and migration in vitro. Our study identified the pro-oncogenic lncRNA THAP9-AS1, which has a higher expression level in GC tissues than in gastritis tissues and which promoted the proliferation and migration of GC cells in vitro.

Conclusion

These findings may provide a potential therapeutic target for H. pylori-associated GC.

The most influential articles in Helicobacter pylori research: A bibliometric analysis

OBJECTIVE

The number of articles that researchers must be familiar with is increasing, along with the importance of selective searching and summarization. This study aimed to assess and characterize the most influential articles in Helicobacter pylori research.

METHODS

We performed a search of the top-100 cited articles using the Web of Science Core Collection (WoSCC) and Google Scholar from their inception to 2018. The top-100 Altmetric Attention Score (AAS) articles based on online media mentions were also searched using the term H pylori. Each article was evaluated for the following characteristics: citation number, title, journal, publication year, and authorship.

RESULTS

The citation number for the top-100 WoSCC articles ranged from 44 to 367. Gut published the largest number of articles (11%). In the top-100 Google Scholar articles, Lancet had the largest number of articles (13%); however, among the top-1000 cited articles published after 2012, Helicobacter published the largest number (46%). The largest number of top-100 AAS articles was published by PLOS Pathogens (6%). PubMed Central articles' citations in WoSCC or Google Scholar showed significant correlation with those from each metric; however, AAS showed no correlation. The proportion of basic research was 36%-37% in top-cited articles; but, 52% in the top-100 AAS articles. No time trend in the number of publications or citations of basic/clinical research in the top-100 bibliometrics was found. "Meta-analysis/systematic review," "gastric cancer," "eradication," and "association" were the most influential title words.

CONCLUSION

This study presents a detailed list of top-100 articles, journals, authors, and topic title words.

The correlation between microRNAs and Helicobacter pylori in gastric cancer

Helicobacter pylori infection and H. pylori-related gastric inflammation can be considered as the most significant promoter of gastric cancer (GC). Recent investigations have evaluated the regulatory function of microRNAs (miRNAs) in H. pylori pathogenesis and H. pylori-related diseases, especially GC. The present study reviewed the correlation between miRNAs and H. pylori in gastrointestinal diseases. Furthermore, the current review highlighted the role of H. pylori pathogen and some H. pylori-related virulence factors in the deregulation of various miRNAs, especially oncogenic miRNAs (miRs) and their associated molecular pathways. Among the related studies, some have focused on the effects of H. pylori infection on regulatory networks of miRs, while others have highlighted the effects of alterations in the expression level of miRs in H. pylori-related diseases. The connectivity between miRNAs and H. pylori is regulated by various molecular pathways and different molecular targets of miRNAs.

Inhibition of Pathogen Adhesion by Bacterial Outer Membrane-Coated Nanoparticles

Anti-adhesion therapies interfere with the bacterial adhesion to the host and thus avoid direct disruption of bacterial cycles for killing, which may alleviate resistance development. Herein, an anti-adhesion nanomedicine platform is made by wrapping synthetic polymeric cores with bacterial outer membranes. The resulting bacterium-mimicking nanoparticles (denoted "OM-NPs") compete with source bacteria for binding to the host. The "top-down" fabrication of OM-NPs avoids the identification of the adhesins and bypasses the design of agonists targeting these adhesins. In this study, OM-NPs are made with the membrane of Helicobacter pylori and shown to bind with gastric epithelial cells (AGS cells). Treatment of AGS cells with OM-NPs reduces H. pylori adhesion and such anti-adhesion efficacy is dependent on OM-NP concentration and its dosing sequence.

Panning using a phage-displayed random peptide library to identify peptides that antagonize the Helicobacter pylori ArsS acid-sensing domain

Helicobacter pylori is an important etiological factor involved in chronic gastritis, peptic ulcer, and gastric cancer. There are currently no optimal preventive or therapeutic interventions for H. pylori infection. H. pylori survives in the stomach by sensing and adapting to the highly acidic environment by using the two-component signal transduction system that contains the most widely known gastric acid receptor, ArsRS (which is composed of ArsS and ArsR). This study aimed to identify peptides that antagonize the acid-sensing domain of H. pylori ArsS. These peptides could be used to block the acid-sensing signal and thereby hinder H. pylori adaption to acidic environments to prevent its survival. Using proSite, the functional domains (including the N-terminal acid-sensing domain) of H. pylori J99 ArsS were predicted. The purified recombinant ArsS N-terminal acid-sensing protein (P-ArsS-A) was used as the target in a panning protocol in which peptides from the Ph.D.-7 Phage Display Peptide Library that could bind to P-ArsS-A were identified. As a result, eight phage clones that could specifically bind to P-ArsS-A were obtained and five amino acid sequences were identified, including P03 (MMSYPKH) and P06 (LTPMPNW). An in vitro minimum inhibitory concentration (MIC) evaluation showed that P03 and P06 significantly inhibited the growth of H. pylori J99. The MIC of P03 was 8 μM, and the MIC of P06 was >16 μM, indicating that P03 is a stronger inhibitor compared to P06. This was confirmed by colony counting on blood agar plates after P03 and P06 administration. Using homology modeling and molecular docking analysis, it was shown that P03 and P06 could bind to the ArsS N-terminal domain, and there were four shared binding sites: TYR25, ASN39, ARG73, and GLU74. Additionally, one hydrogen bond was found between P03 and ArsS, which is more cohesive than other forms of bonding (van der Waals force, other non-covalent bonds).

Helicobacter pylori-induced YAP1 nuclear translocation promotes gastric carcinogenesis by enhancing IL-1β expression

Gastric cancer (GC) is one of the most common and malignant pathologies, and a significant portion of GC incidences develops from Helicobacter pylori (Hp)-induced chronic gastritis. Although the exact mechanisms of GC are complex and poorly understood, gastric carcinogenesis is a good model to investigate how inflammation and infection collaboratively promote tumorigenesis. Yes-associated protein 1 (YAP1) is the key effector of the Hippo pathway, which is silenced in most human cancers. Herein, we verified the tumor-promoting effect of YAP1 in vitro, in vivo, and in human specimens. We revealed that YAP1 displays nuclear translocation and works with TEAD to activate transcription of the crucial inflammatory cytokine IL-1β in gastric cells infected with Hp. As IL-1ß accounts for inflammation-associated tumorigenesis, this process can lead to gastric carcinogenesis. Thus, in addition to activating proliferation genes, YAP1 also plays a major role in inflammation amplification by activating inflammatory cytokine genes. Excitingly, our research demonstrates that transfection of mutant plasmid YAP-5SA/S94A or addition of the drug verteporfin, both of which are thought to disrupt the YAP1-TEAD interaction, can arrest the carcinogenesis process. These findings can provide new approaches to GC treatment.

Astaxanthin from Shrimp Cephalothorax Stimulates the Immune Response by Enhancing IFN-γ, IL-10, and IL-2 Secretion in Splenocytes of Helicobacter Pylori-Infected Mice

Infection with Helicobacter pylori is a critical cause of gastrointestinal diseases. A crucial host response associated with H. pylori infection includes gastric inflammation, which is characterized by a sustained recruitment of T-helper (Th) cells to the site of infection and distinct patterns of cytokine production. Adequate nutritional status, especially frequent consumption of dietary antioxidants, appears to protect against infection with H. pylori. The aim of the present study was to investigate whether astaxanthin (AXT) from shrimp cephalothorax may modulate cytokine release of splenocytes in H. pylori-infected mice (n = 60). Six- to eight-week-old female mice were divided into three groups (n = 20 per group) to receive a daily oral dose of 10 or 40 mg of AXT for six weeks. After six weeks, a trend toward interferon gamma (IFN-γ) upregulation was found (40 mg; p < 0.05) and a significant dose-dependent increase of interleukin 2 (IL-2) and IL-10 (both p < 0.05) was observed. These results suggest that AXT induces higher levels of IL-2 and a shift to a balanced Th1/Th2 response by increasing IFN-γ and augmenting IL-10. We concluded that AXT may influence the pattern of cytokines during H. pylori infection.

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.

CagW, a VirB6 homologue interacts with Cag-type IV secretion system substrate CagA in Helicobacter pylori

Protein translocating Cag type IV secretion system of Helicobacter pylori is a diverse multi-protein complex. Here, we have characterized one of its key subunit CagW to identify its interacting partners. Our results demonstrate for the first time that this VirB6 homologue interacts with the substrate of the secretion system CagA. CagW forms multimer and its absence affects cellular levels of pilus forming components, CagL, CagI and CagH. Our results support the notion that the protein is essential for the transport of CagA across the bacterial membrane barrier and would aid in improving our understanding of structural and functional aspects of the inner membrane part of Cag-T4SS channel complex for the passage of substrate CagA.

Gastric Parietal Cell Physiology and Helicobacter pylori-Induced Disease

Acidification of the gastric lumen poses a barrier to transit of potentially pathogenic bacteria and enables activation of pepsin to complement nutrient proteolysis initiated by salivary proteases. Histamine-induced activation of the PKA signaling pathway in gastric corpus parietal cells causes insertion of proton pumps into their apical plasma membranes. Parietal cell secretion and homeostasis are regulated by signaling pathways that control cytoskeletal changes required for apical membrane remodeling and organelle and proton pump activities. Helicobacter pylori colonization of human gastric mucosa affects gastric epithelial cell plasticity and homeostasis, promoting epithelial progression to neoplasia. By intervening in proton pump expression, H pylori regulates the abundance and diversity of microbiota that populate the intestinal lumen. We review stimulation-secretion coupling and renewal mechanisms in parietal cells and the mechanisms by which H pylori toxins and effectors alter cell secretory pathways (constitutive and regulated) and organelles to establish and maintain their inter- and intracellular niches. Studies of bacterial toxins and their effector proteins have provided insights into parietal cell physiology and the mechanisms by which pathogens gain control of cell activities, increasing our understanding of gastrointestinal physiology, microbial infectious disease, and immunology.

In Vitro and In Vivo Activities of Zinc Linolenate, a Selective Antibacterial Agent against Helicobacter pylori

Helicobacter pylori is a major global pathogen, and its infection represents a key factor in the etiology of various gastric diseases, including gastritis, peptic ulcers, and gastric carcinoma. The efficacy of current standard treatment for H. pylori infection including two broad-spectrum antibiotics is compromised by toxicity toward the gut microbiota and the development of drug resistance, which will likely only be resolved through novel and selective antibacterial strategies. Here, we synthesized a small molecule, zinc linolenate (ZnLla), and investigated its therapeutic potential for the treatment of H. pylori infection. ZnLla showed effective antibacterial activity against standard strains and drug-resistant clinical isolates of H. pyloriin vitro with no development of resistance during continuous serial passaging. The mechanisms of ZnLla action against H. pylori involved the disruption of bacterial cell membranes and generation of reactive oxygen species. In mouse models of multidrug-resistant H. pylori infection, ZnLla showed in vivo killing efficacy comparable and superior to the triple therapy approach when use as a monotherapy and a combined therapy with omeprazole, respectively. Moreover, ZnLla treatment induces negligible toxicity against normal tissues and causes minimal effects on both the diversity and composition of the murine gut microbiota. Thus, the high degree of selectivity of ZnLla for H. pylori provides an attractive candidate for novel targeted anti-H. pylori treatment.

The usefulness of inflammatory biomarkers in diagnosing child and adolescent's gastritis: STROBE compliant article

Neutrophil to lymphocyte ratio (NLR) is a simple, noninvasive, inexpensive inflammatory marker that can useful in the assessment of inflammatory activity, especially in pediatric ages. The aim of our study was to establish correlations between the presence of Helicobacter pylori (HP) proved histologically and NLR in children.A prospective, case-control study was performed on 137 pediatric patients aged between 1 and 18 years, admitted in a Pediatric Tertiary Hospital from Romania, between April 2016 and January 2018. According to the histologic examination, the children were divided into 2 groups: group 1: 50 children with HP infection, and group 2: 87 children without any pathologic findings.The mean age for the study group was 12.86 ± 3.796 years, whereas for control group, it was 12.10 ± 3.879 years (P = .3001). HP infection was significantly more frequent among children from rural area (P = .0089). Epigastric pain and loss of appetite were significantly associated with HP infection (P = .0350 /P = .0281). We noticed that the leukocyte and neutrophil counts were significantly higher in group 1 (P = .0076/P = .0306). We did not find any significant statistical differences between the 2 groups in terms of lymphocytes, erythrocyte sedimentation rate, and NLR or other assessed laboratory parameters. Regarding the IgA antibodies anti-HP and rapid urease test, they were both significantly associated with histologically confirmed HP infection (P < .0001).Even though, we did not identify significant differences in term of NLR between HP-induced gastritis children and healthy controls, the mean NLR values were higher HP-positive patients.

Concurrent detection of cagA, vacA, sodB and hsp60 virulence genes and their relationship with clinical outcomes of disease in Helicobacter pylori isolated strains of southwest of Iran

BACKGROUND AND OBJECTIVES

Helicobacter pylori is a Gram-negative spiral-shaped bacterium that contaminates more than half of the world's inhabitants, and infection with this bacterium is associated with some gastric disorders. Also, 5% to 10% of H. pylori genes are specific to this bacterium and many bacterial virulence factors fall into this group. The cagA, vacA, sodB and hsp60 are among important virulence factors of H. pylori.

MATERIALS AND METHODS

A gastric biopsy specimen was taken from 341 gastric patients and cultivated on a Colombia agar plate, containing various antibiotics, such as vancomycin, amphotericin B, and trimethoprim & polymyxin B, and incubated for 3 to 10 days under microaerophilic conditions at 37°C. PCR was used to detect the ureC, cagA, vacA, sodB and hsp60 genes.

RESULTS

In this study, 131 isolates were identified as H. pylori. The prevalence of cagA, vacA, sodB and hsp60 were 74%, 100%, 92.4% and 96.2%, respectively. The correlation between the clinical forms of the disease and the virulence genes were analyzed by statistical tests and no significant correlation was found.

CONCLUSION

The obtained results are similar to some studies conducted in different parts of the world and is different in other cases. This discrepancy is due to the difference in the type of gastric disorders, sample size and methodology.

Gastric Subserous Vaccination With Helicobacter pylori Vaccine: An Attempt to Establish Tissue-Resident CD4+ Memory T Cells and Induce Prolonged Protection

Tissue-resident memory T (Trm) cells are enriched at the sites of previous infection and required for enhanced protective immunity. However, the emergence of Trm cells and their roles in providing protection are unclear in the field of Helicobacter pylori (H. pylori) vaccinology. Here, our results suggest that conventional vaccine strategies are unable to establish a measurable antigen (Ag)-specific memory cell pool in stomach; in comparison, gastric subserous injection of mice with micro-dose of Alum-based H. pylori vaccine can induce a pool of local CD4+ Trm cells. Regional recruitment of Ag-specific CD4+ T cells depends on the engagement of Ag and adjuvant-induced inflammation. Prior subcutaneous vaccination enhanced this recruitment. A stable pool of Ag-specific CD4+ T cells can be detected for 240 days. Two weeks of FTY720 administration in immune mice suggests that these cells do not experience the recirculation. Immunohistochemistry results show that close to the vaccination site, abundant CD4+T cells locate on epithelial niches, independent of lymphocyte cluster. Paradigmatically, Ag-specific CD4+ T cells with a phenotype of CD69+CD103- are preferential on lymphocytes isolated from epithelium. Upon Helicobacter infection, CD4+ Trm cells orchestrate a swift recall response with the recruitment of circulating antigen-specific Th1/Th17 cells to trigger a tissue-wide pathogen clearance. This study investigates the vaccine-induced gastric CD4+ Trm cells in a mice model, and highlights the need for designing a vaccine strategy against H. pylori by establishing the protective CD4+ Trm cells.

Proteoglycans and Immunobiology of Cancer-Therapeutic Implications

Disparity during the resolution of inflammation is closely related with the initiation and progression of the tumorigenesis. The transformed cells, through continuously evolving interactions, participate in various exchanges with the surrounding microenvironment consisting of extracellular matrix (ECM) components, cytokines embedded in the ECM, as well as the stromal cells. Proteoglycans (PGs), complex molecules consisting of a protein core into which one or more glycosaminoglycan (GAG) chains are covalently tethered, are important regulators of the cell/matrix interface and, consecutively, biological functions. The discrete expression of PGs and their interacting partners has been distinguished as specific for disease development in diverse cancer types. In this mini-review, we will critically discuss the roles of PGs in the complex processes of cancer-associated modulation of the immune response and analyze their mechanisms of action. A deeper understanding of mechanisms which are capable of regulating the immune response could be harnessed to treat malignant disease.

The relationship between gastric microbiota and gastric disease

Traditionally, the stomach was believed to be a sterile organ unsuitable for microbiota growth. However, the discovery of H. pylori subverted this conception. With the development of molecular techniques, an abundance of microbiota of great diversity was found in the stomach. In addition, various lines of evidence suggest that the gastric microbiota plays a critical role in the development and progression of the gastric disease.The gastrointestinal microbiome plays an important role in various physiologic and pathologic processes.

Non-Gaussian, non-ergodic, and non-Fickian diffusion of tracers in mucin hydrogels

Native mucus is polymer-based soft-matter material of paramount biological importance. How non-Gaussian and non-ergodic is the diffusive spreading of pathogens in mucus? We study the passive, thermally driven motion of micron-sized tracers in hydrogels of mucins, the main polymeric component of mucus. We report the results of the Bayesian analysis for ranking several diffusion models for a set of tracer trajectories [C. E. Wagner et al., Biomacromolecules, 2017, 18, 3654]. The models with "diffusing diffusivity", fractional and standard Brownian motion are used. The likelihood functions and evidences of each model are computed, ranking the significance of each model for individual traces. We find that viscoelastic anomalous diffusion is often most probable, followed by Brownian motion, while the model with a diffusing diffusion coefficient is only realised rarely. Our analysis also clarifies the distribution of time-averaged displacements, correlations of scaling exponents and diffusion coefficients, and the degree of non-Gaussianity of displacements at varying pH levels. Weak ergodicity breaking is also quantified. We conclude that-consistent with the original study-diffusion of tracers in the mucin gels is most non-Gaussian and non-ergodic at low pH that corresponds to the most heterogeneous networks. Using the Bayesian approach with the nested-sampling algorithm, together with the quantitative analysis of multiple statistical measures, we report new insights into possible physical mechanisms of diffusion in mucin gels.

Three-Dimensional Organoids in Cancer Research: The Search for the Holy Grail of Preclinical Cancer Modeling

Most solid tumors become therapy resistant and will relapse, with no durable treatment option available. One major impediment to our understanding of cancer biology and finding innovative approaches to cancer treatment stems from the lack of better preclinical tumor models that address and explain tumor heterogeneity and person-to-person differences in therapeutic and toxic responses. Past cancer research has been driven by inadequate in vitro assays utilizing two-dimensional monolayers of cancer cells and animal models. Additionally, animal models do not truly mimic the original human tumor, are time consuming, and usually costly. New preclinical models are needed for innovation in cancer translational research. Hence, it is time to welcome the three-dimensional (3D) organoids: self-organizing cells grown in 3D culture systems mimicking the parent tissues from which the primary cells originate. The 3D organoids offer deeper insights into the crucial cellular processes in tissue and organ formation and pathological processes. Generation of near-perfect physiological microenvironments allow 3D organoids to couple with gene editing tools, such as the clustered regularly interspersed short palindromic repeat (CRISPR)/CRISPR-associated 9 and the transcription activator-like effector nucleases to model human diseases, offering distinct advantages over current models. We explain in this expert review that through recapitulating patients' normal and tumor tissues, organoid technology can markedly advance personalized medicine and help reveal once hidden aspects of cancers. The use of defined tissue- or organ-specific matrices, among other factors, will likely allow organoid technology to realize its potential in innovating many fields of life sciences.

NLRP3 Controls the Development of Gastrointestinal CD11b+ Dendritic Cells in the Steady State and during Chronic Bacterial Infection

The gastric lamina propria is largely uncharted immunological territory. Here we describe the evolution and composition of the gastric, small intestinal, and colonic lamina propria mononuclear phagocyte system during the steady state and infection with the gastric pathogen Helicobacter pylori. We show that monocytes, CX₃CR1^hi macrophages, and CD11b⁺ dendritic cells are recruited to the infected stomach in a CCR2-dependent manner. All three populations, but not BATF3-dependent CD103⁺ DCs, sample red fluorescent protein (RFP)⁺Helicobacter pylori (H. pylori). Mice reconstituted with human hematopoietic stem cells recapitulate several features of the myeloid cell-H. pylori interaction. The differentiation in and/or recruitment to gastrointestinal, lung, and lymphoid tissues of CD11b⁺ DCs requires NLRP3, but not apoptosis-associated speck-like protein containing a carboxy-terminal CARD (ASC) or caspase-1, during steady-state and chronic infection. NLRP3^-/- mice fail to generate Treg responses to H. pylori and control the infection more effectively than wild-type mice. The results demonstrate a non-canonical inflammasome-independent function of NLRP3 in DC development and immune regulation.

Prevalence and genotyping of Helicobacter pylori in endoscopic biopsy samples from a Chinese population

Background:

Helicobacter pylori inhabit the gastric mucosa of humans and are associated with several gastrointestinal diseases which include gastric cancer, peptic ulcer, chronic gastritis and gastric mucosa-associated lymphoid tissue lymphoma. Helicobacter pylori exhibit a high degree of genetic variability and are associated with its epidemiological, pathological characteristics and dynamics of transmission. The objective of the study was to determine the prevalence and genetic heterogeneity of H. pylori isolated from endoscopic biopsy samples from a Chinese population.

Methods:

Gastric biopsy samples from 86 patients (males, 55; females, 35) who presented to the endoscopic section for various gastrointestinal abnormalities were collected. The samples were subjected to a real-time polymerase chain reaction (PCR) and microbial culture for the isolation of H. pylori. Further, the isolates were subjected to randomly amplified polymorphic DNA (RAPD) and restriction fragment length polymorphism (RFLP) analysis.

Results:

Of the 86 gastric biopsy samples, 61 (70.9%) samples were positive for rapid urease test and 37 (43%) samples (28 from male and nine from female) grew H. pylori. Among the biopsy samples subjected to real-time PCR, 39 (45.3%) samples were found to be positive for H. pylori. The RAPD analysis yielded 15 different patterns (four to 17 different sized fragments per strain). The phylogenetic analysis of RAPD yielded 22 clusters at a similarity level ranging from 63% to 100%. RFLP analysis yielded nine different patterns (two to six different sized fragments per strain). Two major restriction patterns were identified, of which 14 (37.8%) strains forms the most common pattern (genotype I) followed by five (13.5%, genotype II) strains with an intra-strain similarity of 100%.

Conclusions:

The overall prevalence of H. pylori was 45.3%. Despite reports on the declining trend in the prevalence of H. pylori infections, our prevalence rate was still higher than those reported from other developed countries. However, further studies involving a large sample size and covering more regions of China is highly warranted.

Role of abnormal microRNA expression in Helicobacter pylori associated gastric cancer

Epidemiological studies have shown that Helicobacter pylori (HP) infection is a risk factor for gastric cancer (GC). HP infection may induce the release of pro-inflammatory mediators, and abnormally increase the level of reactive oxygen species (ROS), nitric oxide (NO), and cytokines in mucosal epithelial cells of the stomach. However, the specific mechanism underlying the pathogenesis of HP-associated GC is still poorly understood. Recent studies have revealed that abnormal microRNA expression may affect the proliferation, differentiation, and apoptosis of mucosal epithelial cells of the stomach to further influence GC occurrence, development, and metastasis. Herein, we summarize the role of abnormal microRNAs in the regulation of HP-associated GC progression. Abnormal microRNA expression in HP-positive GC may be a biomarker for GC diagnosis, occurrence, and development as well as its targeted treatment and prognosis.

Promising Recent Strategies with Potential Clinical Translational Value to Combat Antibacterial Resistant Surge

Multiple drug resistance (MDR) for the treatment of bacterial infection has been a significant challenge since the beginning of the 21st century. Many of the small molecule-based antibiotic treatments have failed on numerous occasions due to a surge in MDR, which has claimed millions of lives worldwide. Small particles (SPs) consisting of metal, polymer or carbon nanoparticles (NPs) of different sizes, shapes and forms have shown considerable antibacterial effect over the past two decades. Unlike the classical small-molecule antibiotics, the small particles are less exposed so far to the bacteria to trigger a resistance mechanism, and hence have higher chances of fighting the challenge of the MDR process. Until recently, there has been limited progress of clinical treatments using NPs, despite ample reports of in vitro antibacterial efficacy. In this review, we discuss some recent and unconventional strategies that have explored the antibacterial efficacy of these small particles, alone and in combination with classical small molecules in vivo, and demonstrate possibilities that are favorable for clinical translations in near future.

The Helicobacter pylori HopQ outermembrane protein inhibits immune cell activities

We previously showed that the colorectal cancer colonizing bacterium Fusobacterium nucleatum protects tumors from immune cell attack via binding of the fusbacterial Fap2 outer-membrane protein to TIGIT, a checkpoint inhibitory receptor expressed on T cells and NK cells. Helicobacter pylori, the causative agent for peptic ulcer disease, is associated with the development of gastric adenocarcinoma and MALT lymphoma. The HopQ outer-membrane adhesin of H. pylori was recently shown to bind carcinoembryonic antigen-related cell adhesion molecules (CEACAMs) including CEACAM1, an inhibitory receptor expressed mainly by activated T and NK cells. Here we investigated the possibility that similar to Fap2, HopQ can also inhibit immune cell activities by interacting with CEACAM1. We used several approaches to confirm that HopQ indeed interacts with CEACAM1, and show that CEACAM1-mediated activation by HopQ, may inhibit NK and T cell functions.

Decreased IL-17RB expression impairs CD11b+CD11c- myeloid cell accumulation in gastric mucosa and host defense during the early-phase of Helicobacter pylori infection

Interleukin-17 receptor B (IL-17RB), a member of the IL-17 receptor family activated by IL-17B/IL-17E, has been shown to be involved in inflammatory diseases. However, the regulation and function of IL-17RB in Helicobacter pylori (H. pylori) infection, especially in the early-phase is still unknown. Here, we found that gastric IL-17RB mRNA and protein were decreased in gastric mucosa of both patients and mice infected with H. pylori. In vitro experiments show that IL-17RB expression was down regulated via PI3K/AKT pathway on gastric epithelial cells (GECs) stimulated with H. pylori in a cagA-involved manner, while in vivo studies showed that the effect was partially dependent on cagA expression. IL-17E was also decreased during the early-phase of H. pylori infection, and provision of exogenous IL-17E resulted in increased CD11b⁺CD11c^- myeloid cells accumulation and decreased bacteria colonization within the gastric mucosa. In the early-phase of H. pylori infection, IL-17E-IL-17RB promoted gastric epithelial cell-derived CXCL1/2/5/6 to attract CD11b⁺CD11c^- myeloid cells, and also contributed to host defense by promoting the production of antibacterial protein Reg3a. This study defines a negative regulatory network involving IL-17E, GECs, IL-17RB, CD11b⁺CD11c^- myeloid cells, and Reg3a in the early-phase of H. pylori infection, which results in an impaired host defense within the gastric microenvironment, suggesting IL-17RB as a potential early intervening target in H. pylori infection.

The Sweeping Role of Cholesterol Depletion in the Persistence of Helicobacter pylori Infections

The ability of Helicobacter pylori to persist lifelong in the human gastric mucosa is a striking phenomenon. It is even more surprising since infection is typically associated with a vivid inflammatory response. Recent studies revealed the mechanism by which this pathogen inhibits the epithelial responses to IFN-γ and other central inflammatory cytokines in order to abolish an effective antimicrobial defense. The mechanism is based on the modification and depletion of cholesterol by the pathogen's cholesterol-α-glucosyltransferase. It abrogates the assembly of numerous cytokine receptors due to the reduction of lipid rafts. Particularly, the receptors for IFN-γ, IL-22, and IL-6 then fail to assemble properly and to activate JAK/STAT signaling. Consequently, cholesterol depletion prevents the release of antimicrobial peptides, including the highly effective β-defensin-3. Intriguingly, the inhibition is spatially restricted to heavily infected cells, while the surrounding epithelium continues to respond normally to cytokine stimulation, thus providing a platform of the intense inflammation typically observed in H. pylori infections. It appears that pathogen and host establish a homeostatic balance between tightly colonized and rather inflamed sites. This homeostasis is influenced by the levels of available cholesterol, which potentially exacerbate H. pylori-induced inflammation. The observed blockage of epithelial effector mechanisms by H. pylori constitutes a convincing explanation for the previous failures of T-cell-based vaccination against H. pylori, since infected epithelial cells remain inert upon stimulation by effector cytokines. Moreover, the mechanism provides a rationale for the carcinogenic action of this pathogen in that persistent infection and chronic inflammation represent a pro-carcinogenic environment. Thus, cholesterol-α-glucosyltransferase has been revealed as a central pathogenesis determinant of H. pylori.

Role of NOD1 and ALPK1/TIFA Signalling in Innate Immunity Against Helicobacter pylori Infection

The human pathogen Helicobacter pylori interacts intimately with gastric epithelial cells to induce inflammatory responses that are a hallmark of the infection. This inflammation is a critical precursor to the development of peptic ulcer disease and gastric cancer. A major driver of this inflammation is a type IV secretion system (T4SS) encoded by the cag pathogenicity island (cagPAI), present in a subpopulation of more virulent H. pylori strains. The cagPAI T4SS specifically activates signalling pathways in gastric epithelial cells that converge on the transcription factor, nuclear factor-κB (NF-κB), which in turn upregulates key immune and inflammatory genes, resulting in various host responses. It is now clear that H. pylori possesses several mechanisms to activate NF-κB in gastric epithelial cells and, moreover, that multiple signalling pathways are involved in these responses. Two of the dominant signalling pathways implicated in NF-κB-dependent responses in epithelial cells are nucleotide-binding oligomerisation domain 1 (NOD1) and a newly described pathway involving alpha-kinase 1 (ALPK1) and tumour necrosis factor (TNF) receptor-associated factor (TRAF)-interacting protein with forkhead-associated domain (TIFA). Although the relative roles of these two pathways in regulating NF-κB-dependent responses still need to be clearly defined, it is likely that they work cooperatively and non-redundantly. This chapter will give an overview of the various mechanisms and pathways involved in H. pylori induction of NF-κB-dependent responses in gastric epithelial cells, including a 'state-of-the-art' review on the respective roles of NOD1 and ALPK1/TIFA pathways in these responses.

Mechanisms of Inflammasome Signaling, microRNA Induction and Resolution of Inflammation by Helicobacter pylori

Inflammasome-controlled transcription and subsequent cleavage-mediated activation of mature IL-1β and IL-18 cytokines exemplify a crucial innate immune mechanism to combat intruding pathogens. Helicobacter pylori represents a predominant persistent infection in humans, affecting approximately half of the population worldwide, and is associated with the development of chronic gastritis, peptic ulcer disease, and gastric cancer. Studies in knockout mice have demonstrated that the pro-inflammatory cytokine IL-1β plays a central role in gastric tumorigenesis. Infection by H. pylori was recently reported to stimulate the inflammasome both in cells of the mouse and human immune systems. Using mouse models and in vitro cultured cell systems, the bacterial pathogenicity factors and molecular mechanisms of inflammasome activation have been analyzed. On the one hand, it appears that H. pylori-stimulated IL-1β production is triggered by engagement of the immune receptors TLR2 and NLRP3, and caspase-1. On the other hand, microRNA hsa-miR-223-3p is induced by the bacteria, which controls the expression of NLRP3. This regulating effect by H. pylori on microRNA expression was also described for more than 60 additionally identified microRNAs, indicating a prominent role for inflammatory and other responses. Besides TLR2, TLR9 becomes activated by H. pylori DNA and further TLR10 stimulated by the bacteria induce the secretion of IL-8 and TNF, respectively. Interestingly, TLR-dependent pathways can accelerate both pro- and anti-inflammatory responses during H. pylori infection. Balancing from a pro-inflammation to anti-inflammation phenotype results in a reduction in immune attack, allowing H. pylori to persistently colonize and to survive in the gastric niche. In this chapter, we will pinpoint the role of H. pylori in TLR- and NLRP3 inflammasome-dependent signaling together with the differential functions of pro- and anti-inflammatory cytokines. Moreover, the impact of microRNAs on H. pylori-host interaction will be discussed, and its role in resolution of infection versus chronic infection, as well as in gastric disease development.

Current and Future Treatment of Helicobacter pylori Infections

Helicobacter pylori is one of the most common human pathogens and it has been estimated that about 50% of the world's population is currently infected. The present consensus is that, unless there are compelling reasons, all H. pylori infections should be cured. Since the 1990s, different national and international guidelines for the management of H. pylori-related diseases have been published and periodically updated regarding indications for treatment, diagnostic procedures, and preferred treatment regimens. Most guidelines provide sophisticated meta-analyses examining the outcome of different regimens done in regions with variable, often high rates of resistance to antibiotics, for which the prevalence and effects of resistance was often ignored. Although successful antimicrobial therapy must be susceptibility-based, increasing antimicrobial resistance and general unavailability of susceptibility testing have required clinicians to generally rely on empiric regimens. Antibiotics resistance of H. pylori has reached alarming high levels worldwide, which has an effect to efficacy of treatment. The recommendations should provide regimes for multi-resistant infections or for those where susceptibility testing is unavailable or refused. The first rule is to use only proven locally effective therapies. Because of patient intolerances, drug allergies, and local experiences, the clinicians should have at least two options for first-line therapy. As with any antimicrobial therapy, a thorough review of prior antibiotic use is invaluable to identify the presence of probably resistance. The second key is patient education regarding potential and expected side-effects and the importance of completing the course of antibiotics. We also review here triple therapies, sequential-concomitant, hybrid therapies, bismuth therapies, dual therapy, vonoprazan, modern antibiotic treatments, probiotics and vaccination.

Effect of patchouli alcohol on Helicobacter pylori-induced neutrophil recruitment and activation

Neutrophil infiltration typically occurs in Helicobacter pylori (H. pylori)-induced acute gastritis; however, this immune response fails to eradicate H. pylori in vivo. Moreover, reactive oxygen species (ROS), which are generated by neutrophils, cause severe damage to gastric mucosa. Patchouli alcohol (PA) has been reported to have effective anti-oxidative and anti-H. pylori activities, and we investigated its effects on H. pylori-induced neutrophil recruitment and activation in this research. In neutrophil recruitment experiment, H. pylori was injected into rat air pouch to explore the effects of PA (10, 20 and 40 mg/kg) on acute inflammatory response. The results revealed that PA significantly reduced the weight of exudate and the number of neutrophils in the air pouch. Meanwhile, remarkable decrements in TNF-α and IL-8 levels in exudates were observed. In neutrophil activation experiment, rat neutrophils were isolated and activated by using 50 μg/mL H. pylori water-soluble surface protein with or without the treatment of PA (5, 10 or 20 μmol/L). Results indicated that PA not only significantly inhibited the production of ROS, but also reduced the gene and protein expressions of p22/p47-phoxes, and the binding of p22/p47-phoxes. Furthermore, the influence of PA on the neutrophil activation genes of H. pylori (h-nap and sabA) was investigated, and the results showed that expressions of h-nap and sabA were remarkably decreased after PA treatment. In conclusion, PA reduced the recruitment and activation of neutrophils induced by H. pylori, as shown by its inhibition of pro-inflammatory factor generation, p22/p47-phoxes function and H. pylori neutrophil activation-related gene expression.

Bacteria-Host Interactions in Multiple Sclerosis

Multiple sclerosis (MS) is caused by a complex interaction of genetic and environmental factors. Numerous causative factors have been identified that play a role in MS, including exposure to bacteria. Mycobacteria, Chlamydia pneumoniae, Helicobacter pylori, and other bacteria have been proposed as risk factors for MS with different mechanisms of action. Conversely, some pathogens may have a protective effect on its etiology. In terms of acquired immunity, molecular mimicry has been hypothesized as the mechanism by which bacterial structures such as DNA, the cell wall, and intracytoplasmic components can activate autoreactive T cells or produce autoantibodies in certain host genetic backgrounds of susceptible individuals. In innate immunity, Toll-like receptors play an essential role in combating invading bacteria, and their activation leads to the release of cytokines or chemokines that mediate effective adaptive immune responses. These receptors may also be involved in central nervous system autoimmunity, and their contribution depends on the infection site and on the pathogen. We have reviewed the current knowledge of the influence of bacteria on MS development, emphasizing the potential mechanisms of action by which bacteria affect MS initiation and/or progression.

Nanosized food additives impact beneficial and pathogenic bacteria in the human gut: a simulated gastrointestinal study

Nanotechnology provides the food industry with new ways to modulate various aspects of food. Hence, engineered nanoparticles (NPs) are increasingly added to food and beverage products as functional ingredients. However, the impact of engineered as well as naturally occurring NPs on both commensal and pathogenic microorganisms within the gastrointestinal tract (GI) is not fully understood. Here, well-defined synthetic NPs and bacterial models were used to probe nanoparticle–bacteria interactions, from analytical to in situ to in vitro. NP–bacteria complexation occurred most efficiently for small NPs, independent of their core material or surface charge, but could be reduced by NPs’ steric surface modifications. Adsorption to bacteria could also be demonstrated for naturally occurring carbon NPs isolated from beer. Complex formation affected the (patho)biological behavior of both the NPs and bacteria, including their cellular uptake into epithelial cells and phagocytes, pathogenic signaling pathways, and NP-induced cell toxicity. NP–bacteria complex formation was concentration-dependently reduced when the NPs became coated with biomolecule coronas with sequential simulation of first oral uptake and then the GI. However, efficient NP adsorption was restored when the pH was sufficiently low, such as in simulating the conditions of the stomach. Collectively, NP binding to enteric bacteria may impact their (patho)biology, particularly in the stomach. Nanosized-food additives as well as naturally occurring NPs may be exploited to (rationally) shape the microbiome. The information contained in this article should facilitate a “safe by design” strategy for the development and application of engineered NPs as functional foods ingredients.

Engineered or naturally occurring nanoparticles could potentially affect the bacteria in the gut. A study led by Dana Westmeier and Roland Stauber from University Medical Center of Mainz, Germany probed the nanoparticle–bacteria interactions in situ. They found that NP–bacteria complex occurred most efficiently for small NPs, independent of their core material or surface charge. The complex formation affected the (patho)biological behavior of both the NPs and bacteria, particularly under conditions that simulate the stomach. The result shows that both engineered and naturally occurring nanoparticles could be exploited to shape the gut microbiome. The study can offer guidelines for future development and application of nanoparticles in food industry.