Topical, immunomodulatory epoxy-tiglianes induce biofilm disruption and healing in acute and chronic skin wounds

The management of antibiotic-resistant, bacterial biofilm infections in chronic skin wounds is an increasing clinical challenge. Despite advances in diagnosis, many patients do not derive benefit from current anti-infective/ antibiotic therapies. Here, we report a novel class of naturally occurring and semisynthetic epoxy-tiglianes, derived from the Queensland blushwood tree (Fontainea picrosperma), and demonstrate their antimicrobial activity (modifying bacterial growth and inducing biofilm disruption), with structure/activity relationships established against important human pathogens. In vitro, the lead candidate EBC-1013 stimulated protein kinase C (PKC)-dependent neutrophil reactive oxygen species (ROS) induction and NETosis and increased expression of wound healing-associated cytokines, chemokines, and antimicrobial peptides in keratinocytes and fibroblasts. In vivo, topical EBC-1013 induced rapid resolution of infection with increased matrix remodeling in acute thermal injuries in calves. In chronically infected diabetic mouse wounds, treatment induced cytokine/chemokine production, inflammatory cell recruitment, and complete healing (in six of seven wounds) with ordered keratinocyte differentiation. These results highlight a nonantibiotic approach involving contrasting, orthogonal mechanisms of action combining targeted biofilm disruption and innate immune induction in the treatment of chronic wounds.