Helicobacter pylori Outer Membrane Protein 18 (Hp1125) Is Involved in Persistent Colonization by Evading Interferon- γ Signaling

Helicobacter pylori Outer Membrane Proteins and Virulence Factors: Potential Targets for Novel Therapies and Vaccines

Helicobacter pylori is a gastric oncopathogen that infects over half of the world's human population. It is a Gram-negative, microaerophilic, helix-shaped bacterium that is equipped with flagella, which provide high motility. Colonization of the stomach is asymptomatic in up to 90% of people but is a recognized risk factor for developing various gastric disorders such as gastric ulcers, gastric cancer and gastritis. Invasion of the human stomach occurs via numerous virulence factors such as CagA and VacA. Similarly, outer membrane proteins (OMPs) play an important role in H. pylori pathogenicity as a means to adapt to the epithelial environment and thereby facilitate infection. While some OMPs are porins, others are adhesins. The epithelial cell receptors SabA, BabA, AlpA, OipA, HopQ and HopZ have been extensively researched to evaluate their epidemiology, structure, role and genes. Moreover, numerous studies have been performed to seek to understand the complex relationship between these factors and gastric diseases. Associations exist between different H. pylori virulence factors, the co-expression of which appears to boost the pathogenicity of the bacterium. Improved knowledge of OMPs is a major step towards combatting this global disease. Here, we provide a current overview of different H. pylori OMPs and discuss their pathogenicity, epidemiology and correlation with various gastric diseases.

Identification of anti-Helicobacter pylori antibody signatures in gastric intestinal metaplasia

BACKGROUND

Chronic Helicobacter pylori infection may induce gastric intestinal metaplasia (IM). We compared anti-H. pylori antibody profiles between IM cases and non-atrophic gastritis (NAG) controls.

METHODS

We evaluated humoral responses to 1528 H. pylori proteins among a discovery set of 50 IM and 50 NAG using H. pylori protein arrays. Antibodies with ≥ 20% sensitivity at 90% specificity for either group were selected and further validated in an independent set of 100 IM and 100 NAG using odds ratios (OR). A validated multi-signature was evaluated using the area under the receiver operating characteristics curve (AUC) and net reclassification improvement (NRI).

RESULTS

Sixty-two immunoglobulin (Ig) G and 11 IgA antibodies were detected in > 10%. Among them, 22 IgG and 6 IgA antibodies were different between IM and NAG in the discovery set. Validated antibodies included 11 IgG (anti-HP1177/Omp27/HopQ [OR = 8.1, p < 0.001], anti-HP0547/CagA [4.6, p < 0.001], anti-HP0596/Tipα [4.0, p = 0.002], anti-HP0103/TlpB [3.8, p = 0.001], anti-HP1125/PalA/Omp18 [3.1, p = 0.001], anti-HP0153/RecA [0.48, p = 0.03], anti-HP0385 [0.41, p = 0.006], anti-HP0243/TlpB [0.39, p = 0.016], anti-HP0371/FabE [0.37, p = 0.017], anti-HP0900/HypB/AccB [0.35, p = 0.048], and anti-HP0709 [0.30, p = 0.003]), and 2 IgA (anti-HP1125/PalA/Omp18 [2.7, p = 0.03] and anti-HP0596/Tipα [2.5, p = 0.027]). A model including all 11 IgG antibodies (AUC = 0.81) had better discriminated IM and NAG compared with an anti-CagA only (AUC = 0.77) model (NRI = 0.44; p = 0.001).

CONCLUSIONS

Our study represents the most comprehensive assessment of anti-H. pylori antibody profiles in IM. The target antigens for these novel antibodies may act together with CagA in the progression to IM. Along with other biomarkers, specific H. pylori antibodies may identify IM patients, who would benefit from surveillance.

Antibacterial action of acriflavine hydrochloride for eradication of the gastric pathogen Helicobacter pylori

Helicobacter pylori, a type 1 carcinogen, accounts for numerous gastric cancer-related deaths worldwide. Repurposing existing drugs or developing new ones for a combinatorial approach against increasing antimicrobial resistance is the need of the hour. This study highlights the efficacy of acriflavine hydrochloride (ACF-HCl) in inhibiting the growth of H. pylori reference strain and antibiotic-resistant clinical isolates at low concentrations. ACF-HCl inhibits H. pylori growth at MIC value 10 times less than that in Escherichia coli, another Gram-negative bacteria. Furthermore, ACF-HCl demonstrates synergistic effect with clarithromycin, a commonly used antibiotic against H. pylori. ACF-HCl treatment also eradicates H. pylori infection in the mice model efficiently. Our in vitro data indicate that bacterial membrane is the prime target. The novel action of ACF-HCl against antibiotic-resistant clinical isolates, synergistic effect with the conventional antibiotic clarithromycin and eradication of H. pylori from infected mice highlight the potential of ACF-HCl as a promising therapeutic agent against H. pylori by itself as well as for combinatorial therapy.

Risk factors for recurrence of Helicobacter pylori infection after successful eradication in Chinese children: A prospective, nested case-control study

BACKGROUND

Limited research has been published on the recurrence of Helicobacter pylori infection and risk factors in Chinese children. Our study aimed to identify risk factors for Helicobacter pylori infection recurrence after successful eradication in children.

MATERIALS AND METHODS

A prospective, nested case-control study was performed. A cohort of 230 children with successful eradication of Helicobacter pylori in Baoding (China) was selected from January 2018 to February 2019. A standardized questionnaire was used to obtain socioeconomic details. Eradication regimens and Helicobacter pylori antibiotic susceptibility testing results were also recorded. Interleukin-1β level, interferon-γ level, and genetic susceptibility (IFNGR1 and PTPRZ1 gene polymorphisms) were analyzed. All children were followed for 1 year.

RESULTS

Among 218 (94.8%) children who were successfully followed, 41 children (18.8%) had a Helicobacter pylori infection recurrence. The recurrence rate was higher in children ≤10 years old than >10 years old (22.8% vs 7.1%, P = .01). There was no significant difference between the recurrence group and the non-recurrence group in terms of types of therapy and antibiotic sensitivity (P > .05). Multivariable regression results indicated that residence in urban areas, higher household income, and having lunch at home were significantly protective against recurrence (OR 0.155, 0.408, and 0.351 respectively), whereas Helicobacter pylori infection in family members increased the risk of recurrence (OR 2.283). The levels of IL-1β and IFN-γ exhibited no significant difference between the recurrence group and the non-recurrence group. The allele frequency of G in the IFNGR1-56 site, A in the IFNGR1-600 site, and T in the IFNGR1-565 site was significantly higher in the recurrence group when compared to the non-recurrence group (P < .05).

CONCLUSIONS

The Helicobacter pylori infection recurrence rate is high in children in Baoding region and is closely correlated to socioeconomic factors. The IFNGR1 gene polymorphism may be an independent risk factor for Helicobacter pylori infection recurrence.

Immune Cell Signaling by Helicobacter pylori: Impact on Gastric Pathology

Helicobacter pylori represents a highly successful colonizer of the human stomach. Infections with this Gram-negative bacterium can persist lifelong, and although in the majority of cases colonization is asymptomatic, it can trigger pathologies ranging from chronic gastritis and peptic ulceration to gastric cancer. The interaction of the bacteria with the human host modulates immune responses in different ways to enable bacterial survival and persistence. H. pylori uses various pathogenicity-associated factors such as VacA, NapA, CGT, GGT, lipopolysaccharide, peptidoglycan, heptose 1,7-bisphosphate, ADP-heptose, cholesterol glucosides, urease and a type IV secretion system for controlling immune signaling and cellular functions. It appears that H. pylori manipulates multiple extracellular immune receptors such as integrin-β₂ (CD18), EGFR, CD74, CD300E, DC-SIGN, MINCLE, TRPM2, T-cell and Toll-like receptors as well as a number of intracellular receptors including NLRP3, NOD1, NOD2, TIFA and ALPK1. Consequently, downstream signaling pathways are hijacked, inducing tolerogenic dendritic cells, inhibiting effector T cell responses and changing the gastrointestinal microbiota. Here, we discuss in detail the interplay of bacterial factors with multiple immuno-regulatory cells and summarize the main immune evasion and persistence strategies employed by H. pylori.

Characterization of the immunomodulatory and anti-Helicobacter pylori properties of the human gastric isolate Lactobacillus rhamnosus UCO-25A

The ability to form biofilms and the potential immunomodulatory properties of the human gastric isolate Lactobacillus rhamnosus UCO-25A were characterized in vitro. It was demonstrated that L. rhamnosus UCO-25A is able to form biofilms on abiotic and cell surfaces, and to modulate the inflammatory response triggered by Helicobacter pylori infection in gastric epithelial cells and THP-1 macrophages. L. rhamnosus UCO-25A exhibited a substantial anti-inflammatory effect in both cell lines and improved IL-10 levels produced by challenged macrophages. Additionally, UCO-25A protected AGS cells against H. pylori infection with a higher pathogen inhibition when a biofilm was formed. Given the importance of inflammation in H. pylori-mediated diseases, the differential modulation of the inflammatory response in the gastric mucosa by an autochthonous strain is an attractive alternative for improving H. pylori eradication and reducing the severity of the diseases that arise from the resulting chronic inflammation.

Helicobacter pylori: molecular basis for colonization and survival in gastric environment and resistance to antibiotics. A short review

Helicobacter pylori is a human-specific pathogen with a strict tropism for the gastric mucosa. This bacterium infects around half of the world population and is the main responsible for gastritis, peptic ulcer and, in some cases, for the pathogenesis of gastric cancer. Nevertheless, disease development in infected subjects depends not only on the bacterium, but also on the host genetic predisposition and on environmental factors. The fascinating question of how the bacterium can survive in the gastric environment has stimulated research in this field. It is now clear that H. pylori is able to colonize and adhere to the gastric epithelium through several mechanisms, including the breakdown of urea with production of the cell-toxic ammonia. The resulting raise in pH neutralizes acidity of the stomach, thereby allowing the bacterium to safely cross the mucus layer to the epithelial surface. Current challenges regard understanding the mechanisms of antibiotic resistance and how to overcome it. Lately, an increasing H. pylori resistance rate to antibiotics has been reported and several molecular bases for this phenomenon described. In this review, we highlight the current knowledge on mechanisms supporting H. pylori resistance to gastric environment and to therapy.

In vitro and in vivo effects of suloctidil on growth and biofilm formation of the opportunistic fungus Candida albicans

As the most frequent fungal pathogen in humans, Candida albicans can develop serious drug resistance because its biofilms are resistant to most antifungal agents; this leads to an urgent need to develop novel antifungals. Here, we evaluated the efficacy of an antithrombotic drug, suloctidil, against C. albicans biofilms in vitro and in vivo. We found that suloctidil is effective to inhibit C. albicans biofilm, with a minimum inhibitory concentration (MIC₈₀) of 4 μg/mL, a biofilm inhibiting concentration (BIC₈₀) of 16 μg/mL and a biofilm eradicating concentration (BEC₈₀) of 64 μg/mL. Furthermore, the concentration-dependent characteristics of suloctidil were shown by its time-kill curves. Scanning electron microscopy images clearly revealed the morphological effects of suloctidil on biofilm. Yeast-to-hyphal form switching is a key virulence factor of C. albicans; therefore, we performed hyphal growth tests and observed that suloctidil inhibited yeast-to-hyphal form switching. This result was consistent with the down-regulation of hypha-specific gene (HWP1, ALS3, and ECE1) expression levels after suloctidil treatment. In vivo, 256 μg/mL of suloctidil significantly reduced fungal counts (P<0.01) compared to that in groups without treatment; the treatment group induced a slight histological reaction, especially when the treatment lasted for 5 days (P<0.01). Taken together, our data suggest that suloctidil is a potential antifungal agent.

The Bifunctional Enzyme SpoT Is Involved in the Clarithromycin Tolerance of Helicobacter pylori by Upregulating the Transporters HP0939, HP1017, HP0497, and HP0471

Clarithromycin (CLA) is a commonly recommended drug for Helicobacter pylori eradication. However, the prevalence of CLA-resistant H. pylori is increasing. Although point mutations in the 23S rRNA are key factors for CLA resistance, other factors, including efflux pumps and regulation genes, are also involved in the resistance of H. pylori to CLA. Guanosine 3′-diphosphate 5′-triphosphate and guanosine 3′,5′-bispyrophosphate [(p)ppGpp)], which are synthesized by the bifunctional enzyme SpoT in H. pylori, play an important role for some bacteria to adapt to antibiotic pressure. Nevertheless, no related research involving H. pylori has been reported. In addition, transporters have been found to be related to bacterial drug resistance. Therefore, this study investigated the function of SpoT in H. pylori resistance to CLA by examining the shifts in the expression of transporters and explored the role of transporters in the CLA resistance of H. pylori. A ΔspoT strain was constructed in this study, and it was shown that SpoT is involved in H. pylori tolerance of CLA by upregulating the transporters HP0939, HP1017, HP0497, and HP0471. This was assessed using a series of molecular and biochemical experiments and a cDNA microarray. Additionally, the knockout of genes hp0939, hp0471, and hp0497 in the resistant strains caused a reduction or loss (the latter in the Δhp0497 strain) of resistance to CLA. Furthermore, the average expression levels of these four transporters in clinical CLA-resistant strains were considerably higher than those in clinical CLA-sensitive strains. Taken together, our results revealed a novel molecular mechanism of H. pylori adaption to CLA stress.