Date of Award

Summer 8-15-2018

Author's School

Graduate School of Arts and Sciences

Author's Department

Biology & Biomedical Sciences (Immunology)

Degree Name

Doctor of Philosophy (PhD)

Degree Type



Specific gut commensal bacteria improve host health by eliciting mutualistic regulatory T (Treg) cells responses. However, the bacteria that induce effector T (Teff) cells during inflammation are unclear. Here, we addressed this by analyzing bacterial-reactive T cell receptor (TCR) transgenic cells and TCR repertoires in a murine colitis model. Unexpectedly, we found that mucosal-associated Helicobacter species triggered both Treg responses during homeostasis and Teff responses during colitis, as suggested by an increased overlap between the Teff/Treg TCR repertoires with colitis. In fact, 4/6 Treg TCRs tested recognized mucosal-associated Helicobacter species in vitro and in vivo. By contrast, the marked expansion of luminal Bacteroides species seen during colitis did not trigger a commensurate Teff response. Unlike other Treg cell-inducing bacteria, Helicobacter species are known pathobionts and cause disease in immunodeficient mice. Thus, our study suggests a model in which mucosal bacteria elicit context-dependent Treg or effector cell responses to facilitate intestinal tolerance or inflammation.


English (en)

Chair and Committee

Chyi-Song Hsieh

Committee Members

Paul Allen, Marco Colonna, Takeshi Egawa, Thaddeus Stappenbeck,


Permanent URL: 2018-08-15