Project summary
Maintenance of homeostasis at barrier tissues is essential for mammalian health. At these sites, the concerted
communication of different cell lineages is central for integrating a wide range of signals, to promote responses
against noxious stimuli while preventing exacerbated responses against benign stimuli. The skin represents an
organ where neuro-immune interactions may be of major biological significance, as it is one of the largest
interfaces between the body and the environment, integrating signals including temperature, mechanical
stimulus, tissue damage, and pathogenic and commensal microbes. Both the nervous and immune systems are
involved in sensing potentially damaging perturbations and mounting appropriate responses for the avoidance
and clearance of noxious stimuli. Recently, we successfully identified the existence of a cellular neuro-immune
circuit formed by the interaction of sensory neurons and regulatory T cells (Treg cells). This neuro-immune circuit
between Treg cells and sensory nerves is mediated at least partially through Treg cell production of enkephalins,
endogenous opioids that induce analgesia. Through enkephalin production Treg cells dampen nociceptor
activation to prevent exacerbated skin inflammation. We additionally find that other non-neuronal skin resident
populations can produce enkephalins. The work proposed in this application seeks to uncover how endogenous
opioid signaling mediates communication between sensory neurons and immune cells to regulate immune
homeostasis in the skin. Understanding the roles for distinct sources of endogenous opioids may lead to the
therapeutic harnessing of these for the treatment of chronic conditions, and may provide alternatives to the use
of exogenous opioids. In addition, this project will, at a global scale, dissect the heterogeneity of responses in
neuronal populations innervating the skin to different pathological contexts, and how these responses relate to
their interactions with immune cells. This project will provide new insights on the molecular underpinnings of
endogenous analgesics’ role in tissue homeostasis, as well as further our understanding on how sensory
neurons respond to different types of inflammation, two key concepts that may have major implications on novel
therapies for chronic conditions involving pain, itch and inflammation.