Natural Killer T Cell Modulation of Cutaneous Wound Healing

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DESCRIPTION (provided by applicant): Natural Killer T (NKT) cells are innate lymphocytes that recognize glycolipid antigens in the context of the MHC-I-like molecule, CD1d. To date, the physiologic roles identified for NKT cells have been limited to immunoregulation primarily in the fields of autoimmunity, cancer, immunologic tolerance, and more recently anti-microbial immunity. Through experiments that led to this application, we discovered that NKT cells play a central role in the cutaneous wound healing process. Using two different mouse models of wound healing (scald burns and excisional wounds), two different strains of NKT cell deficient mice, and systemic blockade of NKT cell activation, we observed that NKT cells appear to regulate key aspects of the early wound healing process. When NKT cells were either genetically absent or their activation was blocked systemically, cutaneous wounds exhibited differential expression of a select subset of cytokines (TNF1, TGF21) and neutrophil and monocyte-macrophage chemoattractants (MIP-2, KC, MIP-11, MIP-12) early (0-3 days) after injury. Most strikingly, when NKT cells were absent or their activation was blocked, cutaneous wounds closed more quickly. Since a role for NKT cells in dermal wound healing has not been described to date, the purpose of this two year R21 exploratory application is to characterize / confirm the role of NKT cells in wound healing and to test the hypothesis that NKT cells regulate wound repair via modulation of early inflammatory signals. Two aims are proposed that will expand upon our preliminary findings. The first aim will confirm that NKT cells regulate wound healing by comparing the kinetics and magnitude of key wound healing parameters (wound closure, re-epithelialization, re-vascularization, inflammatory cell infiltrate) in NKT cell deficient mice vs. NKT deficient mice that are re-constituted with NKT cells. The requirement for NKT cell activation will be comfirmed via analysis of the kinetics and magnitude of the same key parameters in mice that are treated with an antibody that blocks NKT cell activation. The second aim will use a combination of immunofluorescence microscopy and molecular biologic techniques to 1) confirm if and when NKT cells infiltrate healing wounds, 2) determine whether NKT cells regulate the infiltration of neutrophils and monocyte-macrophages, and 3) determine whether NKT cells regulate either the kinetics or magnitude of inflammatory mediators critical to the intiation of wound repair. Based on our preliminary findings, we anticipate that this exploratory application will provide the basis for understanding the mechanisms by which NKT cells regulate the wound healing process and provide potential new avenues of investigation for therapeutic approaches to aberrant wound healing, such as what occurs with burns, diabetes, psoriasis, and keloids.