Selective inhibition of PKR by C16 accelerates diabetic wound healing by inhibiting NALP3 expression in mice

摘要

Abstract Objective and design To understand the expression of dsRNA-dependent protein kinase R (PKR) in impaired diabetic wounds, hyperglycemia was induced in C57/BL6 mice with streptozotocin. Murine macrophage cell line, Raw 264.7, stimulated with high glucose and LPS was used to mimic diabetic wound environment in in-vitro.Materials Macrophages stimulated with HG?+?LPS, in presence and absence of PKR inhibitor (C16) and wound tissue samples from topically treated mice with C16, were analyzed for the expression of PKR, NALP3, active caspase-1, mature IL-1β and phosphorylation of PKR and eIF2α. Wounds tissues were also analyzed for inflammatory cell infiltration by immunohistochemistry, angiogenesis by CD31 staining, collagen expression by western blotting, expression of CD206+?macrophages by flow cytometry and wound strength by texture analyzer.Results PKR and NALP3 were found to be upregulated in macrophages stimulated with HG?+?LPS as well as in impaired diabetic wounds. PKR inhibition using C16 ameliorated expression of NALP3, caspase-1, IL-1β and phosphorylation of PKR and eIF2α, in macrophages and also in diabetic wounds. Treatment with C16 promoted the wound healing in diabetic mice by increasing collagen synthesis, reducing infiltration of F4/80+ macrophages and MPO+ neutrophil cells, increased angiogenesis, and increased number of M2 macrophages.Conclusion PKR inhibition using C16 accelerates the wound healing process in diabetic mice by decreasing NALP3-mediated IL-1β maturation.