Apoptosis of gastric lymphocytes in Helicobacter pylori-infected rhesus macaques (original) (raw)
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Digestive diseases and sciences, 1999
Increased mucosal apoptosis is seen in H. pylori-infected gastric tissue; however, the precise mechanism by which this organism triggers programmed cell death is poorly understood and is investigated in this study. One pathway for induction of apoptosis is the Fas Ag pathway. Normal gastric and small bowel tissue express low levels of Fas antigen and nondetectable levels of Fas ligand. Consequent to H. pylori infection, there is elevated expression of Fas antigen in mucosal cells concurrent with Fas ligand expressing lymphocytes. This prompted us to investigate the potential role of Fas in mediating H. pylori-related apoptosis. It has been shown that inflammatory cytokines are abundant in H. pylori-infected tissue and that cytokines regulate the expression of Fas Ag in various tissue types. Using cell culture, we examine the role of specific inflammatory cytokines in activating this pathway. This communication presents the first evidence to implicate the Fas pathway in mediating apo...
Helicobacter pyloriinduces apoptosis of rat gastric parietal cells
American Journal of Physiology-Gastrointestinal and Liver Physiology, 2002
Gastric Helicobacter pylori infection may lead to multifocal atrophic corpus gastritis associated with loss of epithelial cells as well as glandular structures. The current work investigated H. pylori effects on cell death of isolated, nontransformed rat parietal cells (PC). Highly enriched rat PC (>97%) were isolated from gastric mucosa and cultured in serum-free medium over 24 h. The cells were cocultured over 8 h with cytotoxin-associated immunodominant protein (cagA)+/vacuolating toxin (vacA)+or with cagA−/vacA−H. pylori laboratory strains and also with H. pylori mutants deleted in several genes of the cag pathogenicity island. Staphylococcus aureus or Campylobacter jejuni were used as controls. Apoptosis was determined by terminal deoxynucleotidyl transferase dUTP nick-end labeling staining and electron microscopy. Interleukin (IL)-8 and cytokine-induced neutrophil chemoattractant (CINC)-1 secretion was measured by ELISA. Activation of nuclear factor-κB (NF-κB) was studied i...
Induction of gastric epithelial apoptosis by Helicobacter pylori
Gut, 1996
Background-Helicobacter pyloni may promote gastric carcinogenesis through increasing gastric epithelial cell proliferation. How H pylon does so is unknown. Programmed, non-necrotic, cell death (apoptosis) occurs throughout the gut and is linked to proliferation. It was hypothesised that H pylori may induce hyperproliferation through increasing apoptosis. Aim-To measure the effect of H pyloni infection on gastric epithelial apoptosis in situ. Patients-Patients with duodenal ulcers treated to eradicate H pylori and patients with H pylori negative non-ulcer dyspepsia. Methods-Retrospective quantification of apoptotic epithelial cells in situ from formalin fixed biopsy specimens, counted after staining by terminal uridine deoxynucleotidyl nick end-labelling. Results-In the uninfected stomach, apoptotic cells were rare and situated in the most superficial portion of gastric glands (mean 2.9% of epithelial cells). In H pyloni infection, they were more numerous and were located throughout the depth of gastric glands, comprising 16.8% of epithelial cells, falling to 3.1% after H pyloni eradication, p=0017.
World journal of gastroenterology : WJG, 2004
To investigate the relations between tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) and Helicobacter pylori (H pylori) infection in apoptosis of gastric epithelial cells and to assess the expression of TRAIL on the surface of infiltrating T-cells in H pylori-infected gastric mucosa. Human gastric epithelial cell lines and primary gastric epithelial cells were co-cultured with H pylori in vitro, then recombinant TRAIL proteins were added to the culture. Apoptosis of gastric epithelial cells was determined by a specific ELISA for cell death. Infiltrating lymphocytes were isolated from H pylori-infected gastric mucosa, and expression of TRAIL in T cells was analyzed by flow cytometry. The apoptosis of gastric epithelial cell lines and primary human gastric epithelial cells was mildly increased by interaction with either TRAIL or H pylori alone. Interestingly, the apoptotic indices were markedly elevated when gastric epithelial cells were incubated with both TRAIL and H...
In situ correlation of cytokine secretion and apoptosis inHelicobacter pylori-associated gastritis
American Journal of Physiology-Gastrointestinal and Liver Physiology, 2002
Tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) are important for the pathogenesis of Helicobacter pylori-associated gastritis and peptic ulcer disease. Gastric biopsies from H. pylori-positive and -negative patients were used to examine the in situ correlation of TNF-α and IFN-γ with epithelial cell apoptosis, bacterial load, and histological parameters of gastritis. From the same patients, we isolated H. pylori-specific T cell lines and clones and examined their ex vivo release of proinflammatory cytokines. We found a highly significant correlation of TNF-α and IFN-γ production with activity and grade of gastritis ( P < 0.01), H. pylori density ( P = 0.01), epithelial cell apoptosis ( P < 0.001), and Fas/Fas-ligand expression ( P < 0.001). T cell lines and clones were all TCR-αβ+and showed T helper 1 functional phenotype. With the use of serial histological sections, this study showed for the first time the in situ correlation of TNF-α and IFN-γ with epithelial c...
The Journal of Infectious Diseases, 2005
Background. Infection of the gastric mucosa with Helicobacter pylori leads to increased apoptosis. Cytokines and receptors of the tumor necrosis factor (TNF) family are known to be involved in this process. The role that the death-inducing TNF-a-related apoptosis-inducing ligand (TRAIL) and its receptors play, in the context of H. pylori infection, is unknown. Methods. In 74 H. pylori-infected and 51 H. pylori-uninfected gastric antral biopsy specimens, levels of TRAIL mRNA and TRAIL receptor mRNA were determined quantitatively by TaqMan reverse-transcriptase polymerase chain reaction. Recombinant TRAIL-induced apoptosis was measured in human and rat gastric epithelial cells by end-labeling of DNA with fluorescein-dTUP and by fluorescence-activated cell sorter analysis. Results. In patients infected with cagA + /vacAs1 + H. pylori strains, expression of TRAIL and the proapoptotic receptors TRAIL-R1 and-R2 was down-regulated, whereas expression of the antiapoptotic receptors TRAIL-R3 and-R4 was up-regulated. Furthermore, expression of TRAIL and TRAIL-R1 and-R2 correlated inversely with the severity of gastric inflammation. Significant apoptosis of isolated human gastric epithelial cells and highly enriched rat parietal and chief cells was induced by 100 ng/mL TRAIL. Conclusions. Down-regulation of the TRAIL system, in the context of H. pylori infection, may limit exaggerated apoptosis of gastric epithelial cells and destruction of tissue and, therefore, may enable H. pylori to maintain its niche.
Journal of Immunological Methods, 2012
Helicobacter pylori infection is associated with severe chronic inflammation, yet the host immune response is rarely able to clear the bacterium. Thymus derived lymphocyte populations such as T helper 1, T helper 17, and T regulatory cells are known to play important roles in the chronicity of H. pylori infection as well as contributing to ongoing gastric pathology. It is yet to be established how these immune cell populations interact in the gastric environment during H. pylori infection. Mouse models of infection offer an opportunity to investigate these interactions in detail. Flow cytometric analysis provides excellent lymphocyte characterization due to its high specificity, sensitivity and potential to perform multiple simultaneous measurements. However, this requires a viable enriched single cell suspension after adequate tissue dissociation, which poses a challenge due to the heterogeneity of gastric tissue. We have evaluated several isolation techniques and have optimized a protocol to isolate and enrich lymphocytes from the H. pylori-infected murine stomach. EDTA/DTT followed by collagenase IV digestion successfully dissociates an average of 1 × 10 7 cells per mouse. Further enrichment using lympholyte M gradient yields on average 4 × 10 6 CD45 + lymphocytes per stomach. Following isolation we compared lymphocyte stimulation by CD3/CD28, phorbol 12-myristate 13-acetate (PMA) and ionomycin or H. pylori lysate and determined that CD3/CD28 effectively induces stimulation of IFNγ and IL 17A, but impairs Foxp3 expression. Using an optimized protocol we observed a 2-fold increase of CD8 + IFNγexpressing lymphocytes localized specifically to the gastric compartment during H. pylori infection. The mechanisms of H. pylori immunopathogenesis are still considered enigmatic, therefore this optimized protocol can help delineate further novel immune cell targets that mediate H. pylori-induced pathology and identify the correlates of immunity for vaccine development.