Impaired healing of surgical incisions is the second leading cause of chronic wound care in the post-acute setting, about $7 billion annually, according to Medicare. Optimal healing requires coordination and signaling between sensory neurons and the immune system. These neural immune interactions are the focus of this proposal. While the role of peptidergic sensory afferents, which release proinflammatory neuropeptides (i.e., calcitonin gene related peptide (CGRP) and Substance P (Sub P)) in response to injury, have been well studied, the function of nonpeptidergic afferents, those afferents that are neuropeptide-poor, in wound repair have not been well defined. My initial studies suggest nonpeptidergic afferents have a suppressive action on immune signaling. One goal of my research program is to further define the role of these neurons specifically in the inflammatory response evoked by surgical incision and during wound repair. My preliminary studies and published transcriptomic studies have identified myeloid differentiation 1 (MD-1, encoded by gene Ly86), a molecule of the innate immune system, to be expressed predominantly in nonpeptidergic neurons expressing the Mas-related G protein D (MrgprD) receptor. Our preliminary data using MrgprDcre Ly86-/- knockout (MCKO) mice, suggest that MD-1, produced by nonpeptidergic sensory neurons, functions as a regulator of neural-immune communication and has anti-inflammatory effects. Nonpeptidergic afferents, via MD-1, may also promote normal healing. We propose to determine the role of MD-1 in these neurons with regard to the cutaneous inflammatory response, wound healing and resolution of incisional pain. We will determine if loss of neuronal MD-1 alters immune cell recruitment and activation during inflammatory and proliferative healing phases. We will examine tissue architecture as a metric of healing and changes in pain behaviors in relation to the inflammatory state. The finding that MD-1 expressed by neurons regulates the immune response to injury is novel and offers a potential new target for optimizing wound repair. Regional anesthesia is used to manage perioperative pain associated with surgery and has also been demonstrated to be protective of immune cells by decreasing sympathetic tone and its adverse immune effects. However, the role of peripheral nerve blocks (PNBs) in neural immune communication at the surgical site have not been delineated. Another goal of my research program is to characterize the role of PNBs in the immune response to surgical incision. These studies will use the plantar incision model and sciatic nerve blocks in mice to define the effects of PNBs on the immune response to injury and on healing. We will define how type and concentration of local anesthetic and duration of nerve block affects the immune response. Finally, using the MCKO mice, we will determine the effect of PNBs on the role of neuronal MD-1 signaling in surgical incision inflammation and healing.