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T cell tolerance and immunity to commensal bacteria
Katherine M Nutsch1, Chyi-Song Hsieh
1Department of Medicine, Division of Rheumatology, Washington University School of Medicine, St. Louis, MO 63110, United States.
Current Opinion in Immunology
|May 23, 2012
Summary
Gut microbes present foreign antigens, prompting T cell interactions. Different bacteria induce distinct T cell responses, highlighting the need for both tolerance and immunity in gut homeostasis.
Area of Science:
- Immunology
- Microbiology
- Gastroenterology
Background:
- The gastrointestinal tract hosts a vast population of commensal bacteria, presenting a significant source of foreign antigens.
- Mechanical barriers typically prevent bacterial entry, but T cells regularly interact with gut microbiota via specific and non-specific receptors.
Purpose of the Study:
- To investigate the diverse T cell responses elicited by different commensal bacterial species.
- To understand the role of these responses in maintaining gut homeostasis.
Main Methods:
- Analysis of T cell responses (e.g., Th17, Treg) to specific commensal bacteria like segmented filamentous bacteria (SFB), Bacteroides fragilis, and Clostridium species.
- Review of recent data on T cell-microbiota interactions.
Main Results:
- Segmented filamentous bacteria (SFB) promote effector Th17 cell responses.
- Bacteroides fragilis and certain Clostridium species induce regulatory T (Treg) cell responses.
- T cell responses vary depending on the commensal bacterial species encountered.
Conclusions:
- Gut homeostasis is not solely maintained by tolerance but requires a balance of both immune tolerance and immunity towards commensal microbiota.
- Specific commensal bacteria can direct distinct T cell immune pathways, influencing gut health.
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