Dongshui Lu

Efficacy, safety, and immunogenicity of an oral recombinant Helicobacter pylori vaccine in children in China: a randomised, double-blind, placebo-controlled, phase 3 trial

BACKGROUND Helicobacter pylori is one of the most common gastric pathogens, affecting at least half the worlds population, and is strongly associated with gastritis, peptic ulcer, gastric adenocarcinoma, and lymphoma. We aimed to assess the efficacy, safety, and immunogenicity of a three-dose oral recombinant H pylori vaccine in children in China. METHODS We did this randomised, double-blind, placebo-controlled, phase 3 trial at one centre in Ganyu County, Jiangsu Province, China. Healthy children aged 6-15 years without past or present H pylori infection were randomly assigned (1:1), via computer-generated randomisation codes in blocks of ten, to receive the H pylori vaccine or placebo. Participants, their guardians, and study investigators were masked to treatment allocation. The primary efficacy endpoint was the occurrence of H pylori infection within 1 year after vaccination. We did analysis in the per-protocol population. This trial is registered with ClinicalTrials.gov, number NCT02302170. FINDINGS Between Dec 2, 2004, and March 19, 2005, we randomly assigned 4464 participants to either the vaccine group (n=2232) or the placebo group (n=2232), of whom 4403 (99%) participants completed the three-dose vaccination schedule and were included in the per-protocol efficacy analysis. We extended follow-up to 3 years. We recorded 64 events of H pylori infection within the first year (14 events in 2074·3 person-years at risk in the vaccine group vs 50 events in 2089·6 person-years at risk in the placebo group), resulting in a vaccine efficacy of 71·8% (95% CI 48·2-85·6). 157 (7%) participants in the vaccine group and 161 (7%) participants in the placebo group reported at least one adverse reaction. Serious adverse events were reported in five (<1%) participants in the vaccine group and seven (<1%) participants in the placebo group, but none was considered to be vaccination related. INTERPRETATION The oral recombinant H pylori vaccine was effective, safe, and immunogenic in H pylori-naive children. This vaccine could substantially reduce the incidence of H pylori infection; however, follow up over a longer period is needed to confirm the protection of the vaccine against H pylori-associated diseases. FUNDING Chongqing Kangwei Biological Technology.

Increased miR-222 in H. pylori-associated gastric cancer correlated with tumor progression by promoting cancer cell proliferation and targeting RECK.

Little is known about the potential role of microRNAs (miRNAs) in the carcinogenesis of gastric cancer induced by Helicobacter pylori (H. pylori). Here, we showed that microRNA‐222 (miR‐222) was up‐regulated in H. pylori‐infected gastric mucosa and gastric cancer. Ectopic expression of miR‐222 promoted cell proliferation and colony formation in vitro. Mechanistically, we identified RECK as a novel target of miR‐222, and also confirmed their relationship by the inverse correlation of mRNA expression ex vivo. Furthermore, we found that RNA interference silencing of RECK can mimic the oncogenic effects of miR‐222. Collectively, H. pylori may function as an initiator in the process of carcinogenesis by up‐regulating miR‐222, which further participates in the progression of cancer by promoting proliferation and inhibiting RECK.

Increased tumor-infiltrating CD8+Foxp3+ T lymphocytes are associated with tumor progression in human gastric cancer

BackgroundCD8+Foxp3+ T lymphocytes have been detected in tumors. However, the distribution, phenotypic features, and regulation of these cells in gastric cancer remain unknown.MethodsThe levels of CD8+Foxp3+ T lymphocytes in the peripheral blood, tumor-draining lymph nodes, non-tumor tissues, and tumor tissues of patients with gastric cancer were detected by flow cytometry. Foxp3 induction in CD8+Foxp3− T cells was investigated in vitro. The suppressive function of CD8+Foxp3+ T lymphocytes was analyzed by their effect on CD4+ T-cell proliferation and IFN-γ production. The percentages of CD8+Foxp3+ T lymphocytes were evaluated for the association with tumor stage.ResultsThe frequency of CD8+Foxp3+ T lymphocytes in tumor tissues was significantly higher than that in non-tumor tissues, and similar results were also observed in tumor-draining lymph nodes compared with peripheral blood. Most intratumoral CD8+Foxp3+ T lymphocytes were activated effector cells (CD45RA−CD27−). TGF-β1 levels were positively correlated with the frequency of CD8+Foxp3+ T lymphocytes in tumor tissues, and in vitro TGF-β1 could induce the generation of CD8+Foxp3+ T lymphocytes in a dose-dependent manner. Furthermore, intratumoral CD8+Foxp3+ T lymphocytes suppressed the proliferation and IFN-γ production of CD4+ T cells. Finally, intratumoral CD8+Foxp3+ T lymphocytes were significantly increased with tumor progression in terms of tumor-node-metastasis (TNM) stage.ConclusionsOur data have shown that increased intratumoral CD8+Foxp3+ T lymphocytes are associated with tumor stage and potentially influence CD4+ T-cell functions, which may provide insights for developing novel immunotherapy protocols against gastric cancer.

Protection Against Helicobacter pylori Infection by a Trivalent Fusion Vaccine Based on a Fragment of Urease B-UreB414

A multivalent fusion vaccine is a promising option for protection against Helicobacter pylori infection. In this study, UreB414 was identified as an antigenic fragment of urease B subunit (UreB) and it induced an antibody inhibiting urease activity. Immunization with UreB414 partially protected mice from H. pylori infection. Furthermore, a trivalent fusion vaccine was constructed by genetically linking heat shock protein A (HspA), H. pylori adhesin A (HpaA), and UreB414, resulting in recombinant HspA-HpaA-UreB414 (rHHU). Its protective effect against H. pylori infection was tested in BALB/c mice. Oral administration of rHHU significantly protected mice from H. pylori infection, which was associated with H. pylori-specific antibody production and Th1/Th2-type immune responses. The results show that a trivalent fusion vaccine efficiently combats H. pylori infection, and that an antigenic fragment of the protein can be used instead of the whole protein to construct a multivalent vaccine.

Expression, Purification and Characterization of Arginase from Helicobacter pylori in Its Apo Form

Arginase, a manganese-dependent enzyme that widely distributed in almost all creatures, is a urea cycle enzyme that catalyzes the hydrolysis of L-arginine to generate L-ornithine and urea. Compared with the well-studied arginases from animals and yeast, only a few eubacterial arginases have been characterized, such as those from H. pylori and B. anthracis. However, these enzymes used for arginase activity assay were all expressed with LB medium, as low concentration of Mn2+ was detectable in the medium, protein obtained were partially Mn2+ bonded, which may affect the results of arginase activity assay. In the present study, H. pylori arginase (RocF) was expressed in a Mn2+ and Co2+ free minimal medium, the resulting protein was purified through affinity and gel filtration chromatography and the apo-form of RocF was confirmed by flame photometry analysis. Gel filtration indicates that the enzyme exists as monomer in solution, which was unique as compared with homologous enzymes. Arginase activity assay revealed that apo-RocF had an acidic pH optimum of 6.4 and exhibited metal preference of Co2+>Ni2+>Mn2+. We also confirmed that heat-activation and reducing regents have significant impact on arginase activity of RocF, and inhibits S-(2-boronoethyl)-L-Cysteine (BEC) and Nω-hydroxy-nor-Arginine (nor-NOHA) inhibit the activity of RocF in a dose-dependent manner.

Burkholderia pseudomallei survival in lung epithelial cells benefits from miRNA-mediated suppression of ATG10

Burkholderia pseudomallei is the causative agent of melioidosis, a disease with high mortality, which is prevalent in tropical regions of the world. A recent study shows that B. pseudomallei can survive inside mammalian cells because of its ability to actively evade cell autophagy. However, the underlying mechanisms remain unclear. In the present study, based on microarray screening, we found that ATG10 was downregulated following B. pseudomallei infection in A549 human lung epithelial cells. Forced expression of ATG10 accelerated the elimination of intracellular B. pseudomallei by enhancing the process of autophagy. Moreover, MIR4458, MIR4667-5p, and MIR4668-5p were found, by microarray screening, to be upregulated in response to B. pseudomallei infection. These 3 novel miRNAs, MIR4458, MIR4667-5p, and MIR4668-5p, targeted to the 3′-untranslated region of ATG10 in different time-course and spatial manners. Upregulation of these miRNAs reduced the level of ATG10 and inhibited autophagy, leading to increasing survival rate of intracellular B. pseudomallei. Furthermore, the increase of these miRNAs was correlated with the reduced promoter methylation status in A549 cells in response to B. pseudomallei infection. Our results reveal that 3 novel miRNAs regulate autophagy-mediated elimination of B. pseudomallei by targeting ATG10, and provide potential targets for clinical treatment.

Crystallization and preliminary crystallographic studies of Campylobacter jejuni ChuZ, a member of a novel haem oxygenase family.

The haem oxygenase ChuZ from Campylobacter jejuni, a major enteric pathogen in humans, is part of the iron-acquisition mechanism that is involved in bacterial survival and persistence in hosts. The ChuZ-haemin complex has been purified and crystallized and diffraction data have been collected to 2.4 Å resolution. The ChuZ-haemin complex crystals belonged to space group C222(1), with unit-cell parameters a = 106.474, b = 106.698, c = 52.464 Å, α = β = γ = 90°. The asymmetric unit contained one ChuZ monomer, with a Matthews coefficient of 2.58 Å(3) Da(-1).