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Updated: Aug 23, 2026
A Mouse Model for Pathogen-induced Chronic Inflammation at Local and Systemic Sites
Published on: August 8, 2014
Cytokine production in response to endodontic infection in germ-free mice
A P Ribeiro Sobrinho1, S M de Melo Maltos, L M Farias
1Institute of Microbiology Professor Paulo de Góes, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil.
Abstract:
This study evaluated the cytokine profiles (type 1 or type 2) that are triggered by and modulate endodontic periapical infections in the root canal system of germ-free mice. Microorganisms isolated from two patients with pulpal necrosis were inoculated into two groups of experimental animals: group I (Gemella morbillorum) and group II (Bifidobacterium adolescentis, Fusobacterium nucleatum and Clostridium butyricum). In vitro, G. morbillorum induced type 1 cytokine synthesis, while the modulation processed in vivo seemed to have the opposite effect, with a reduction in the basal levels of IL-12 and IFN-gamma, IL-4-independent down-modulation. In vitro, microorganisms from group II, in poly-infection, induced a reduction of type 1 cytokine levels from day 10 to day 20, which seemed to be modulated via IL-4. In vivo, however, a predominance of the immune response to one species over the others occurred.
Insights
This study investigated immune responses to root canal bacteria in germ-free mice. Gemella morbillorum triggered type 1 cytokines in vitro, but suppressed them in vivo, while other bacteria modulated responses via interleukin-4.
Area of Science:
- Microbiology
- Immunology
- Endodontics
Background:
- Endodontic periapical infections involve complex microbial communities.
- Understanding the host immune response, particularly cytokine profiles, is crucial for managing these infections.
- Germ-free animal models offer a controlled environment to study host-microbe interactions.
Purpose of the Study:
- To evaluate the cytokine profiles (type 1 and type 2) triggered by and modulating endodontic periapical infections.
- To compare the immune responses induced by single-species (Gemella morbillorum) versus polymicrobial infections (Bifidobacterium adolescentis, Fusobacterium nucleatum, Clostridium butyricum).
- To investigate the in vitro and in vivo cytokine modulation in a germ-free mouse model.
Main Methods:
- Inoculation of germ-free mice with specific oral microorganisms isolated from patients with pulpal necrosis.
- Assessment of cytokine profiles, including interleukin-12 (IL-12) and interferon-gamma (IFN-gamma) for type 1, and interleukin-4 (IL-4) for type 2 responses.
- Comparison of in vitro cytokine induction with in vivo modulation of immune responses.
Main Results:
- In vitro, Gemella morbillorum induced type 1 cytokine synthesis.
- In vivo, G. morbillorum modulated immune responses, reducing basal levels of IL-12 and IFN-gamma in an IL-4-independent manner.
- Polymicrobial infections in vitro reduced type 1 cytokine levels, modulated by IL-4, while in vivo responses showed a predominance to one species.
Conclusions:
- The in vitro and in vivo immune responses to endodontic pathogens can differ significantly.
- Specific bacterial species and their combinations elicit distinct cytokine profiles, influencing the host's immune strategy.
- Further research is needed to elucidate the complex interplay between oral microbiota and host immunity in endodontic infections.
