[Zhang, Yan] Univ South China, Inst Pathogen Biol, Hengyang 421001, Peoples R China.
Helicobacter pylori;VacA;THP-1 cells;proinflammatory cytokines;apoptosis;nuclear factor kappa B (NF-kappa B)
Vacuolating cytotoxin (VacA) is an important virulence factor in the pathogenesis of Helicobacter pylori-related diseases. The aim of this study was to investigate the function of the amino-terminal 476 residue fragment (p52) of VacA and the possible molecular mechanisms responsible for its induction of proinflammatory cytokines secretion and apoptosis. Human acute monocytic leukemia cell line THP-1 was used as an in vitro model to study proinflammatory cytokines secretion and apoptosis induced by transfection of a recombinant plasmid encoding the amino-terminal 476 residue fragment (p52) of VacA. The results showed that VacA p52 overexpression induced the production of tumor necrosis factor alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), nitric oxide, and reactive oxygen species in THP-1 cells in a time-dependent manner. VacA p52 overexpression also promoted THP-1 cells apoptosis. In addition, VacA p52 triggered the activation of nuclear factor kappa B (NF-kappa B), indicating a possible mechanism for its induction of proinflammatory cytokines secretion and cell apoptosis. Our study demonstrated that the induction of cytokines secretion and apoptosis by VacA p52 in THP-1 cells could be mediated through activation of nuclear factor kappa B.
[Liu, Sheng; Chen, Chaoqun; Cai, Hengling; Tang, Shuangyang; Yu, Minjun; Zhang, Yan; Luo, Jingjing; Liu, Yapu] Institute of Pathogenic Biology, University of South China, Hengyang, Hunan, China
[Zhang, Yan] Univ South China, Inst Pathogen Biol, Hengyang 421001, Hunan, Peoples R China.
Helicobacter pylori;regulatory T cells;CD4;Foxp3
Helicobacter pylori (H. pylori), one of the most common infections, is associated with various clinical outcomes. In addition to inducing inflammation, immunological clearance of the pathogen is often incomplete. Regulatory T cells (Treg cells) have been recently demonstrated to play an important role in H. pylori infection and the final clinical outcome. The aim of this study was to investigate the number and localization of CD4+Foxp3+ Treg cells in stomachs and spleens of H. pylori‐infected mice. The expression levels of Foxp3 as well as anti‐ and pro‐inflammatory cytokines before and after H. pylori triple eradication therapy were examined. We found that the percentages of CD4+Foxp3+ Treg cells out of the lamina propria lymphocytes (LPLs) and spleen lymphocytes in the infection group were higher than the PBS negative control group and the treatment group. H. pylori antigen stimulation was associated with an increased number of Treg cells in vitro. Furthermore, compared with the PBS and treatment groups, a higher mRNA expression level of Foxp3 in the gastric tissue was detected in the infection group. IL‐10 and TGF‐β1 contents were increased significantly in the culture supernatant of spleen lymphocyte stimulated with H. pylori antigen. A marked elevation in serum IFN‐γ level was observed in H. pylori‐infected mice. In addition, gastric tissues of the infection group contained more Foxp3+ cells. These results indicate that the percentage of CD4+Foxp3+ Treg cells are increased in H. pylori‐infected mice, suggesting a role of Treg cells in H. pylori‐induced pathologies, even at the early stages of chronic gastritis and gastric tumorigenesis.
Pathogens and disease,2015年73(4) ISSN：2049-632X
[Liu, Sheng; Li, Xiang; Liu, Anyuan; Tang, Shuangyang; Yu, Minjun; Luo, Jingjing; Liu, Shuo] Institute of Pathogenic Biology, University of South China, Hengyang 421001, Hunan, China;[Zhang, Yan] Institute of Pathogenic Biology, University of South China, Hengyang 421001, Hunan, China email@example.com
[Zhang, Yan] Univ South China, Inst Pathogen Biol, 28 West Changsheng Rd, Hengyang 421001, Hunan, Peoples R China.
This study investigated whether Helicobacter pylori could activate the nucleotide-binding oligomerization domain-like receptor (NLR) family, pyrin domain-containing 3 (NLRP3) inflammasome in human macrophages and the involvement of reactive oxygen species (ROS) in inflammasome activation. Phorbol-12-myristate-13-acetate (PMA)-differentiated human acute monocytic leukemia cell line THP-1 was infected with H. pylori. The levels of pro-inflammatory cytokines interleukin (IL)-1 beta and IL-18 in supernatant were measured by ELISA. Intracellular ROS level was analyzed by flow cytometry. Quantitative real-time PCR and western blot analysis were employed to determine the mRNA and protein expression levels of NLRP3 and caspase-1 in THP-1 cells, respectively. Our results showed that H. pylori infection could induce IL-1 beta and IL-18 production in PMA-differentiated THP-1 cells in a dose-and time-dependent manner. Moreover, secretion of IL-1 beta and IL-18 in THP-1 cells following H. pylori infection was remarkably reduced by NLRP3-specific small interfering RNA treatment. In addition, the intracellular ROS level was elevated by H. pylori infection, which could be eliminated by the ROS scavenger N-acetylcysteine (NAC). Furthermore, NAC treatment could inhibit NLRP3 inflammasome formation and caspase-1 activation and suppress the release of IL-1 beta and IL-18 from H. pylori-infected THP-1 cells. These findings provide novel insights into the innate immune response against H. pylori infection, which could potentially be used for the prevention and treatment of H. pylori-related diseases.