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The inflammatory response in CD1 mice shortly after infection with a CagA+/VacA+ Helicobacter pylori strain
N E van Doorn1, E P van Rees, F Namavar
1Department of Medical Microbiology, Faculty of Medicine, Vrije Universiteit, Amsterdam, The Netherlands.
Abstract:
To investigate the early events of Helicobacter pylori infection in a mouse model, CD1 mice were infected with a type I (CagA+/VacA+) H. pylori strain. Up to 4 weeks after infection the majority of gastric tissue biopsies were positive in culture. Immunohistochemical analysis showed that inflammatory changes started to occur after 3 weeks. Four weeks after infection a significant increase in T cells was observed in the cardia/corpus region of the stomachs of infected mice. These T cells were CD4+ and CD8+, and they were located in an area with increased expression of MHC class II antigens. In 50% of the infected mice also an increased number of mast cells was seen. Furthermore, aggregates of B and T cells were present in the submucosa. Characterization of cytokines by immunohistochemistry showed an increase in IL-5-secreting cells in the inflamed area of the infected stomach. No difference was observed between interferon-gamma (IFN-gamma)-, IL-4- and IL-10-secreting cells in control and infected mice. These results suggest that no polarized T-helper cell response was present at this early phase of infection. Infection with H. pylori also induced a serum response and especially IgG was increased after 4 weeks of infection. However, no particular increase in IgG1, IgG2a or IgG3 isotype was observed. Part of the serum antibodies was directed against lipopolysaccharide (LPS), but no evidence for anti-Lewis antibodies or antibodies against epitopes on the gastric mucosa was found.
Insights
Early Helicobacter pylori infection in mice shows inflammation and T-cell infiltration within 4 weeks. The study found increased IL-5, but no polarized T-helper cell response, suggesting a non-specific immune reaction during early H. pylori gastritis.
Area of Science:
- Immunology
- Microbiology
- Gastroenterology
Background:
- Helicobacter pylori infection is a major cause of gastritis and peptic ulcers.
- Understanding the early immune response is crucial for developing effective treatments.
- A type I H. pylori strain (CagA+/VacA+) was used to mimic human infection.
Purpose of the Study:
- To investigate the early immunological events following H. pylori infection in a mouse model.
- To characterize the cellular and cytokine responses in the gastric mucosa.
- To assess the systemic antibody production during the initial phase of infection.
Main Methods:
- CD1 mice were infected with H. pylori.
- Gastric tissue biopsies were cultured to confirm infection.
- Immunohistochemistry was used to analyze inflammatory cells (T cells, mast cells) and cytokine expression (IL-5, IFN-γ, IL-4, IL-10).
- Serum antibody levels (IgG, isotypes) and specificity were measured.
Main Results:
- H. pylori was cultured from gastric biopsies up to 4 weeks post-infection.
- Inflammatory changes and increased CD4+/CD8+ T cells expressing MHC class II were observed after 3 weeks.
- Increased IL-5-secreting cells were detected, but no polarized T-helper response (Th1/Th2) was evident.
- Elevated total IgG levels were found in sera, with antibodies primarily targeting lipopolysaccharide (LPS).
Conclusions:
- Early H. pylori infection induces gastric inflammation and T-cell infiltration without a polarized T-helper response.
- The immune response is characterized by increased IL-5 and a general increase in IgG production.
- Further research is needed to understand the long-term implications of this early immune response.