Diabetic ulcers are costly chronic wounds and are the leading cause of lower-extremity amputations. Dysfunctional redox balance underlies a key part of diabetic wound repair pathology that results from misregulation of master antioxidant gene regulator Nrf2. While Nrf2 regulation is relevant for wound repair, how Nrf2 onsets a regenerative response is unclear. Using in-depth analyses, we uncover Nrf2 expression in keratinocytes to be vital for physiologic wound repair. In vivo spatio-temporal analysis shows deregulated nuclear translocation of Nrf2 in diabetic wound keratinocytes (WT: 96.97%±3.6%; Db: 22.50%±16.4%; p<.005), which correlates with reduced activation of many antioxidant gene targets (p<.005). To elucidate the role of Nrf2 in the epidermis, we utilized double transgenic mice to conditionally delete Nrf2 in keratinocytes (K14 CreER; Nrf2fl/fl; cKO) in vivo. Importantly, we find loss of epidermal Nrf2 results in a significant wound repair delay that reminisces delays observed in diabetic mice (WT: 16.0±0d; Db: 32±0d; cKO: 33±2d; p<.0005). RNA-seq of cKO wound keratinocytes reveals Nrf2 regulates epidermal release of extrinsic cues that affect non-autologous responses that are critical for regeneration, most notably immune cell guidance (p<.05). The magnitude of this signaling defect is shown through failure of cKO wounds to traffic monocyte/macrophages to the injury site (WT: 130.0±15.0cells/area; cKO 35.0±2.6cells/area; p<.05). This defect results from reduced expression of Ccl2 in cKO wounds, which we find to possess a Nrf2-binding motif that exhibits dynamic Nrf2 binding upon wounding. Induced expression of Nrf2 in primary keratinocytes results in Ccl2 upregulation, and its application is sufficient for restoring physiologic wound regeneration in cKO and diabetic wounds (p<.0001). We provide evidence describing an essential role of Nrf2 in regulating critical wound healing events and provide the basis for continued investigation on its therapeutic value.
A.P. Villarreal Ponce: None. M. Tiruneh-Worku: None. J. Lee: None. J.A. David: None. C. Guerrero-Juarez: None. K. Dammeyer: None. J. Kuhn: None. J. Kwong: None. D. Ceradini: None.
American Diabetes Association/Pathway to Stop Diabetes (1-16-ACE-08 to D.C.)