Endothelial damage occurs early after inhalation injury as measured by increased syndecan-1 levels

Inhalation injury is a significant cause of morbidity and mortality in the burn patient population. However, the pathogenesis of inhalation injury and its potential involvement in burn shock is not well understood. Preclinical studies have shown endothelial injury, as measured by syndecan-1 (SDC-1) levels, to be involved in the increased vascular permeability seen in shock states. Furthermore, the lung has been identified as a site of significant SDC-1 shedding. Here we aim to characterize the contribution of endotheliopathy caused by inhalation alone in a swine model. When comparing injured animals, the fold change of circulating SDC-1 levels from preinjury was significantly higher at 2, 4, and 6 hours postinjury (P = .0045, P = .0017, and P < .001, respectively). When comparing control animals, the fold change of SDC-1 from preinjury was not significant at any timepoint. When comparing injured animals versus controls, the fold change of SDC-1 injured animals was significantly greater at 2, 4, 6, and 18 hours (P = .004, P = .03, P < .001, and P = .03, respectively). Histological sections showed higher lung injury severity compared to control uninjured lungs (0.56 vs 0.38, P < .001). This novel animal model shows significant increases in SDC-1 levels that provide evidence for the connection between smoke inhalation injury and endothelial injury. Further understanding of the mechanisms underlying inhalation injury and its contribution to shock physiology may aid in development of early, more targeted therapies.