IMMUNOPATHOLOGICAL ASPECTS OF THREMAL INJURY

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DESCRIPTION (provided by applicant): Major thermal injury induces a pathophysiological response that has a marked inflammatory/immune component which contributes to numerous complications that include delayed wound healing, increased susceptibility to sepsis and multiple organ failure. A wide range of mediators and cell types closely regulate the post-burn inflammatory process. Nonetheless, the ability of the burn patient to maintain an appropriate balance between inflammatory and anti-inflammatory responses following major burn injury is often disrupted leading to immunopathological complications. In this regard, a unique T-cell subset, gamma delta (7/8) T- cells has the ability to regulate inflammatory and healing processes. Gamma/delta T-cells are likely to be a critical component of the patient's successful recovery from burn injury. Our recent findings support an important multi-faceted role for y/8 T-cells in post-burn immunopathology by demonstrating the following: they are mobilized and activated early post-injury; they regulate post-burn neutrophil migration and; 7/8 T- cells contribute to burn wound healing via the regulation of growth factor, cytokine, and nitric oxide (NO) production at the injury site. While macrophage NO production (which is regulated by y/8 T-cells under certain conditions) is an important mediator of post-burn immune dysfunction, it is also critical to many aspects of wound repair. Burn injury is first and foremost an injury to the skin and a vast majority of burn patients have complications related to healing of the burn or skin graft site. Nonetheless, while y/8 T-cells are important to wound healing, their role in such processes post-burn remains to be clearly elucidated. It is our hypothesis that y/8 T-cells play a critical regulatory role in the post-burn dermal inflammatory response and wound healing that is, in part, mediated by an iNOS-dependent mechanism. The specific aims will determine: 1) the role of y/8 T-cells in post-burn wound healing and the dermal inflammatory response; 2) the role of y/8 T-cells in burn excision and grafting and; 3) the relationship of y/8 T-cells to the post burn wound healing and inflammatory responses in humans. Elucidation of the relationships between y/8 T-cells, the dermal inflammatory response and post-burn wound healing will be vital in the development of improved therapeutic regimes for this critically ill patient population, which could include the novel concept of biotherapy with y/8 T-cells or modulation of native y/8 T-cell activity.