Humans are home to a vast consortium of commensal bacteria that have recently been suggested to be an important component of health. Indeed, disruptions in microbial community structure has been correlated with multiple autoimmune and infectious disease. Given that both pathogenic and commensal bacteria have similar molecular motifs it remains unclear how the host immune system discriminates between good and bad bacteria. Our previous studies have identified a novel signaling pathway employed by T cells to induce tolerance to the commensal microbe, B.fragilis. We identified that this organism produced a polysaccharide (called PSA) that specifically induces tolerant responses by directly ligating toll like receptor 2 (TLR) on a T cell. Thus, PSA represents the incipient member of a novel class of molecules that are expressed by commensal bacteria and control host immunity. TLRs are a class of receptors that have largely been studied in the context of innate immunity. It has only recently been appreciated that TLRs are also expressed on cells of the adaptive immune system including T cells. Our data suggest that T cell intrinsic TLR signaling is an important pathway that regulates host-commensal interactions. This proposal will seek to better understand the signaling pathway that is elicited by PSA through TLR2 on a T cell and understand how T cell intrinsic TLR signaling influences the composition of the microbiota, host development and health.

Public Health Relevance

It has recently been demonstrated that the commensal bacteria that reside on our bodies are instrumental for proper development and health. Indeed, disruptions in the composition of the microbial community are correlated with disease. We have identified a novel signaling pathway utilized by the host to shape the composition of the microbial community, host development and health. A better understanding of this pathway will allow for the development of therapies to shape healthy microbial communities.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
High Priority, Short Term Project Award (R56)
Project #
1R56AI107090-01
Application #
8707594
Study Section
Immunity and Host Defense Study Section (IHD)
Program Officer
Rothermel, Annette L
Project Start
2013-08-15
Project End
2014-08-14
Budget Start
2013-08-15
Budget End
2014-08-14
Support Year
1
Fiscal Year
2013
Total Cost
$350,150
Indirect Cost
$115,150
Name
University of Utah
Department
Pathology
Type
Schools of Medicine
DUNS #
009095365
City
Salt Lake City
State
UT
Country
United States
Zip Code
84112
Petersen, Charisse; Round, June L (2014) Defining dysbiosis and its influence on host immunity and disease. Cell Microbiol 16:1024-33