Gastric mucus alterations associated with murine Helicobacter infection - PubMed (original) (raw)

Gastric mucus alterations associated with murine Helicobacter infection

Julia M Schmitz et al. J Histochem Cytochem. 2009 May.

Abstract

The C57BL/6 mouse has been shown to develop gastric adenocarcinoma after Helicobacter felis infection. This model was used to determine whether mucin and trefoil factor (TFF) expression after infection was altered in a similar fashion to the changes seen in the protective gastric mucus layer of the human stomach after H. pylori infection. Our results indicate that this mouse model mimics many of the changes seen after human H. pylori infection, including increased expression of muc4 and muc5b and loss of muc5ac. These alterations in mucin expression occurred as early as 4 weeks postinfection, before the development of significant mucous metaplasia or gastric dysplasia. The decrease in muc5ac expression occurred only in the body of the stomach and was not secondary to the adaptive immune response to infection, because a similar decrease in expression was seen after infection of B6.Rag-1(-/-) mice, which lack B and T cells. Intriguingly, the increased expression of Muc4 and Muc5b in infected C57BL/6 mice was not seen in the infected B6.Rag-1(-/-) mice. Because B6.Rag-1(-/-) mice do not develop gastric pathology after H. felis infection, these findings point to the potential role of Muc4 and Muc5b in disease progression. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.

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Figures

Figure 1

Figure 1

Disease progression during Helicobacter felis infection in C57BL/6 mice. (A) Histological scores of H. felis infected B6 stomachs postinfection. *p<0.05 compared with B6 mock controls. (B) Colonization scores over the course of the infection. *p<0.05 compared with 4-week B6 _H. felis_–infected stomachs. In these two graphs, the horizontal line represents the median score, and the circles represent individual animals and indicate the numbers of animals used in the experiments in this study. Representative hematoxylin–eosin stains of infected stomachs over time are shown in C–G. (C) A mock-infected mouse showing the normal glandular structure of the stomach (histologic score 0). (D) Four weeks postinfection the stomach shows significant gastritis while maintaining normal gastric glandular architecture (histologic score = 4). (E) A stomach infected for 16 weeks shows significant gastric atrophy, whereas a 52-week infected animal shows intestinal metaplasia (histologic scores of 8 and 9, respectively) (F). (G) A 52-week infected stomach that has gastric carcinoma in situ, as indicated by the invasion of the abnormal gastric glands through the muscularis layer (histologic score = 9). Periodic acid-Schiff (PAS) stains of infected stomachs over time are shown in H–L. The mock-infected shows the normal magenta-stained neutral mucus distribution of the stomach (H). These neutral mucins are not significantly altered 4 weeks after infection (I) but are lost as the infection proceeds and dysplasia and gastric adenocarcinoma develop (J–L). Bar = 50 μm.

Figure 2

Figure 2

Immunofluorescent analysis of mucins in the gastric body after H. felis infection. All photomicrographs shown are representative of the staining seen in all stomachs examined. A (mock), E (16 weeks after H. felis infection), and I (52 weeks after H. felis infection) indicate that there is no change in muc1 immunoreactivity after infection. B (mock), F (16 weeks after H. felis infection), and J (52 weeks after H. felis infection) show that H. felis infection also does not change muc3 immunoreactivity. C (mock), G (16 weeks after H. felis infection), and K (52 weeks after H. felis infection) show that there is increased muc4 immunoreactivity after H. felis infection. D (mock), H (16 weeks after H. felis infection), and L (52 weeks after H. felis infection) are immunostained for muc5ac. There is a loss of muc5ac immunoreactivity in the gastric body as early as 16 weeks postinfection. Bar = 50 μm.

Figure 3

Figure 3

Gastric muc5ac immunoreactivity decreases after H. felis infection. Muc5ac immunoreactivity was analyzed by a semiquantitative scoring system that uses a 0–3 scale. The individual stomach scores for each animal analyzed are indicated by circles, whereas the horizontal line represents the median. *p<0.05 compared with B6 mock controls.

Figure 4

Figure 4

Mucin expression in C57BL/6 and B6.RAG-1−/− _H. felis_–infected mice. (A) Levels of muc5ac immunoreactivity decrease in both the B6 and B6.RAG-1−/− stomach after H. felis infection. Mock animals from all times after infection are combined. *p<0.05 compared with respective mocks. (B) Fold change in RNA expression in _H. felis_–infected B6.RAG-1−/− and B6 stomachs 16 weeks postinfection. *p<0.05 compared with respective mocks, and the number of mice used in the RNA analysis are as shown by the individual symbols in A.

Figure 5

Figure 5

Comparison of gastric body mucin expression in B6.RAG-1−/− _H. felis_–infected or mock-control mice. All photomicrographs shown are representative of the staining seen in all stomachs examined. (A,E) Muc1, (B,F) muc3, (C,G) muc4, and (D,H) muc5ac. A–D are mock-control stomachs. E–H are 16 weeks after H. felis infection. Note that immunoreactivity in B6.RAG-1−/− mice for muc1, 3, and 5ac is similar to that seen in B6 mice with H. felis infection, whereas muc4 immunoreactivity does not increase in infected B6.RAG-1−/− stomachs. This is in contrast to the increase in muc4 seen after H. felis infection of B6 mice (see Figure 2). Bar = 50 μm.

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