The role of Interleukin-10 in Helicobacter pylori infection

Zakaria, Zuraihan (2010) The role of Interleukin-10 in Helicobacter pylori infection. MPhil thesis, University of Nottingham.

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Abstract

Background & Aims: Helicobacter pylori (H. pylori) chronic infection is the major cause of peptic ulceration and gastric cancer. Strains with the cag pathogenicity island (cagPaI) are more strongly associated with disease. In earlier studies, higher levels of interleukin-10 (IL-10) were found in human gastric biopsies with the highest H. pylori colonisation density grading. In the current study, experiments were performed to determine if this effect could be replicated in vitro using human gastric epithelial cell lines. Although IL-10 is abundant in the gastric mucosa, the nature of its interaction with the epithelium is unknown. IL-10 receptor (IL-10R) expression on gastric epithelial cells was therefore investigated.

Materials & Methods: H. pylori was co-cultured with the human gastric epithelial cell lines AGS, MKN28 and MKN45 in the presence or absence of recombinant human IL-10 (rIL-10). Bacterial densities were assessed by viable count assays. Immunofluorescence microscopy, flow cytometry, RT-PCR and western blotting were used to investigate the presence of IL-10R (IL-10Rα and IL-10Rβ subunits) on gastric epithelial cell lines. An IL-10 Fluorokine Kit (R&D Systems) was also used to quantify IL-10 binding onto gastric epithelial cells.

Results: Addition of rIL-10 significantly increased the density of H. pylori cagPaI positive strains indirectly through effects on gastric epithelial cells. No such differences were observed with cagPaI negative strains. AGS cells expressed both IL 10Rα and IL-10Rβ constitutively but IL-10Rβ expression was increased with infection. Conversely, the binding of IL-10 was decreased when AGS cells were infected with H. pylori.

Conclusion: This study highlighted a novel finding of constitutive IL-10R expression in AGS cells. Interestingly, H. pylori infection of AGS cells downregulated the binding of IL-10 to its receptor. The higher level expression of IL-10Rβ following infection was in opposition to this. Possibly IL-10Rβ could be sequestered into other cytokine receptor complexes and therefore is not participate in IL-10 binding. These studies have shown that IL-10 has a more complex role in the interaction between H. pylori and its host. The IL-10 response now also appears to influence the density of H. pylori in the stomach, via cagPaI-dependent effects on epithelial cells. More work must be carried out to investigate the mechanisms behind this effect.

Item Type:Thesis (MPhil)
Supervisors:Robinson, K.
Atherton, J.C.
Faculties/Schools:UK Campuses > Faculty of Medicine and Health Sciences > School of Clinical Sciences
ID Code:1272
Deposited By:mrs zuraihan zakaria
Deposited On:24 Sep 2010 14:26
Last Modified:24 Sep 2010 14:26

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