Interplay Between Langerhans Cells and Sensory Neurons: Impact on Wound Healing and Nociception Following Burn Injuries - PROJECT SUMMARY Effective wound care is of paramount importance for individuals who have sustained burn injuries. Wound healing is intricately associated with the sensations of itching and pain, which can significantly impact a patient's quality of life. Following a burn injury, monocyte-derived Langerhans cells (LCs) are mobilized from the bone marrow and recruited to the epidermal layer, potentially playing a pivotal role in the wound healing process. Furthermore, the sensations of itch and pain are largely mediated by the free nerve endings of nociceptive sensory neurons, often found in close proximity to resident LCs within the epidermis. However, our comprehension of how LCs modulate wound healing, itching, and pain remains notably limited, primarily due to the absence of established methods for selectively manipulating LC activity. Here, we hypothesize that distinct subsets of LCs mediate wound healing, itch, and pain after burn injury. To test this hypothesis, we have successfully applied optogenetics to directly control the activity of LCs by establishing a mouse line that selectively expresses light-sensitive cation channels (ChR2) in LCs. We have also successfully applied chemogenetics to directly control the activity of LCs by establishing a mouse line that selectively expresses Gq- or Gi-biased Designer Receptors Exclusively Activated by Designer Drugs (Gq- or Gi- DREADD) in LCs. The long-term goal of this application is to advance our understanding of the molecular mechanisms behind wound healing, itch, and pain after burn injury regulated by LC-sensory neuron interaction and to offer innovative ways to treat these conditions by targeting LCs. Aim 1 will determine the role of LC-sensory neuron interaction in wound healing using hematopoietic chimeras in which monocyte- derived LCs selectively express Gq- or Gi-DREADD and transgenic mice in which sensory neurons selectively express Gq- or Gi-DREADD. Aim 2 will determine the contribution of LCs to postburn itch and pain using hematopoietic chimeras in which resident LCs selectively express ChR2 or Gi-DREADD, and in vitro calcium imaging from LCs. Aim 3 will genetically define the heterogeneous population of LCs involved in wound healing or nociception after burn injury using single-cell RNAseq. This proposal will help us to understand completely new roles for LCs and how they may regulate wound healing and wound-related itch and pain after burn injury. The successful completion of this proposal would provide a unique approach to treating wound healing, wound-related itch, and pain after burn injury by targeting distinct subsets of LCs.
