Innate Immune Regulation of Wound Re-epithelialization

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PROJECT SUMMARY/ABSTRACT Skin has a remarkable ability to heal wounds through re-epithelialization, a repair process fueled by adult stem cells residing in the epidermis and hair follicles. Following injury, wound-edge keratinocytes proliferate and migrate to initiate wound closure, which is accompanied by activation and infiltration of immune cells. My long-term goal is to elucidate the cellular and molecular basis underlying wound re-epithelialization, how the immune system regulates this process, and how it affects tissue regeneration. Previously we found activation of the transcription factor Stat3 in keratinocytes controls many important aspects of wound re-epithelialization, including basal keratinocyte proliferation, migration and crosstalk with epidermal dendritic T cells (DETCs). However, the molecular mechanism by which wounding triggers Stat3-mediated re-epithelialization and activates the immune system remains unclear and is the subject of this study. Cellular injury is known to produce damage associated molecular patterns (DAMPs) that are sensed by the innate immune system for host protection. We hypothesize that DAMPs produced by skin wounds are sensed by innate immune pattern recognition receptors (PRRs), which then signal to produce cytokines, and further activate Stat3 for wound re-epithelialization. Using a candidate approach and Stat3 activation as a readout, we will first identify, characterize, and verify wound-edge cytokines that influence wound re-epithelialization through epidermal-specific genetic knockouts, gene-expression analysis, and genetic modulation of immune signaling (Aim 1). Next, we describe strategies to identify the immune signaling pathway, upstream PRR, and the cells responsible for the PRR signaling through genetic and biochemical approaches (Aim 2). Finally, we describe an inducible genetic model of wound injury, characterize its similarity to physical wounding, and identify wound- induced ligands using biochemical purification and an in vitro assay (Aim 3). These lines of investigation will 1) offer novel insights into the molecular mechanism of wound initiation and innate immune contribution to skin re-epithelialization, 2) contribute new tools and models to the study of immune regulation and skin repair, and 3) improve our understanding and therapeutic options for autoimmune/autoinflammatory skin conditions and diseases associated with poor wound repair. With an exceptional mentoring team led by Dr. Elaine Fuchs (with Drs. Jean-Laurent Casanova and Daniel Mucida) and a supportive, stimulating training environment at the Rockefeller University, I am ideally positioned to fully develop my technical skills and knowledge in skin biology and immunology. My research, training, and career development will allow me to establish a unique niche in the field of wound-repair and tissue regeneration as an independent investigator.