Cell-cell interactions driving gut inflammation and tolerance

Project summary
The highly specialized intestinal immune system is charged with maintaining tolerance to harmless stimuli from
food and commensal bacteria, while providing protective immunity against pathogens. Dysregulation of this
critical balance can lead to food allergy, inflammatory bowel disease (IBD), or increased susceptibility to enteric
pathogens. Dendritic cells (DCs) are key players in intestinal homeostasis, finely orchestrating immune
responses by presenting luminal antigens and inducing functional differentiation of CD4+ T cells into regulatory
or pro-inflammatory subsets. The cellular mechanisms underlying the decision between tolerance or immunity
to intestinal antigens remain unknown, largely because the identification and characterization of the exact DCs
involved in these processes has been a decades-long technical challenge. To overcome this problem, I
established the use of the LIPSTIC (Labeling Immune Partnerships by SorTagging Intercellular Contacts)
technology in the gut, which enables proximity-dependent labeling of specific intestinal cell-cell interactions. The
main goal of this research proposal is to elucidate the mechanisms that determine whether DCs will induce
regulatory or pro-inflammatory T cells in vivo, by combining the LIPSTIC system with gene targeting, functional
imaging, intersectional genetics, and interaction-based transcriptomics approaches. This proposal tests the
hypothesis that DCs specialized for different functions exist in the intestine and that continuous dynamic
reprogramming of DCs subsets by luminal content dictate tolerance or immunity to food and microbes.
Specifically, this concept will be tested in mice under physiological (tolerance to food and microbes) and
pathological (allergic sensitization, enteric infection, and colitis) scenarios. To this end, the K99 mentored phase
(Aim 1) will reveal the exact nature of the DCs that induce tolerance or inflammation to food and the cellular and
molecular mechanisms by which food-specific pTregs maintain oral tolerance. Next, the R00 independent phase
(Aim 2) will focus on studying immune responses to commensals, with relevance to disorders such as colitis.
Elucidating the DC populations, location and molecular mechanisms involved in tolerance to distinct microbes
will reveal the nature of host-microbe interactions in health and disease. Together, this research program will
lend fundamental insight into the etiology of certain intestinal disorders and will provide foundation for the
development of new therapies for food allergy, colitis, and enteric infections, with profound implications for public
health. The proposed development plan complements my training in mucosal immunology and cellular
interactions with transcriptomics analysis, imaging, and mouse genetics. I will take advantage of the extensive
resources of the Rockefeller University, the mentorship of Dr. Daniel Mucida, Dr. Gabriel Victora and the Advisory
Committee team that will lend expertise in key aspects of the project and career development. At the end of the
mentored phase, I will be equipped with the necessary tools to conduct comprehensive studies at the intersection
of cellular communication and immune response to commensals as an independent investigator.

Grant Number: 4R00AI173537-03
NIH Institute/Center: NIH
Principal Investigator: Maria Cecilia Campos Canesso