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Survey of extra-intestinal immune responses in asymptomatic long-term Campylobacter jejuni-infected mice
Abstract:
Campylobacter jejuni is among the most frequently reported bacterial pathogens causing diarrhea in humans worldwide. We recently reported a murine infection model mimicking key features of human campylobacteriosis. Six days following oral C. jejuni infection immediately after weaning, infant mice developed acute enterocolitis resolving within 2 weeks. Thereafter, C. jejuni could still be isolated from the intestines of asymptomatic mice at low levels accompanied by distinct immune responses, both at intestinal and extra-intestinal locations. We here show that, at day 103 post infection (p.i.), long-term C. jejuni-infected mice exhibited higher numbers of T lymphocytes in liver, lung, kindneys, and cardiac muscle as compared to uninfected controls. In addition, B lymphocytes were slightly higher, but macrophage numbers were significantly lower in liver and lung of C. jejuni-infected versus naive mice. As compared to uninfected control animals, proliferating cells were significantly lower in liver, lung, kidneys, cardiac muscle, and spleen at day 103 p.i., whereas more apoptotic cells were abundant in the spleen with predominance in the red pulp. This study underlines that post-infectious, immunological sequelae at extra-intestinal locations are of importance even in asymptomatic long-term C. jejuni carriers and need to be further studied in order to unravel the underlying molecular mechanisms.
Insights
Long-term Campylobacter jejuni infection in mice leads to lasting immune changes in organs like the liver and lungs, even after the initial illness resolves. These findings highlight the importance of studying extra-intestinal effects in asymptomatic carriers.
Area of Science:
- Immunology
- Microbiology
- Pathogen Research
Background:
- Campylobacter jejuni is a leading cause of bacterial diarrhea globally.
- A murine model of C. jejuni infection shows acute enterocolitis followed by asymptomatic carriage.
- Persistent C. jejuni infection can induce distinct immune responses at intestinal and extra-intestinal sites.
Purpose of the Study:
- To investigate the long-term immunological consequences of C. jejuni infection in extra-intestinal tissues.
- To characterize immune cell populations and cell proliferation/apoptosis in infected mice at day 103 post-infection.
Main Methods:
- Oral C. jejuni infection in infant mice post-weaning.
- Analysis of immune cell populations (T lymphocytes, B lymphocytes, macrophages) in liver, lung, kidneys, and cardiac muscle at day 103 p.i.
- Assessment of cell proliferation and apoptosis in various organs and spleen.
Main Results:
- Long-term C. jejuni infection increased T lymphocyte numbers in liver, lung, kidneys, and cardiac muscle.
- Macrophage numbers were reduced in the liver and lung of infected mice.
- Cell proliferation was lower, while apoptosis was higher in the spleen of infected mice at day 103 p.i.
Conclusions:
- Asymptomatic, long-term C. jejuni carriers exhibit significant post-infectious immunological sequelae in extra-intestinal locations.
- These findings underscore the need for further research into the molecular mechanisms underlying these long-term immune alterations.
- Understanding these effects is crucial for managing C. jejuni infections and their potential chronic complications.
