Locally Activated Mitophagy Contributes to a 'Built-In' Protection Against Early Burn-Wound Progression in Rats Following a Regulation of HIF-1α

Abstract

Background: Deep burn wounds undergo a dynamic progression in the initial or periburn area after insults. The zone of stasis has a higher risk of deterioration and is considered a salvageable target for burn-wound progression. Few studies have explored the role of mitochondrial damage in this process and potential "built-in" self-defense within the human body. Methods: A classic "comb" scald rat model was established in this study. Histological and blood-ow observation were processed based on hematoxylin-eosin staining and laser analysis. Oxidative and apoptotic status were analyzed by commercial kits. Transmission electron microscope, immuno uorescence staining, and western blot were applied to detect the mitophagy happened in the zone of stasis and potential regulators. Adenovirus-based gene-silence contributed to determine the role of HIF-1 as a regulatory mediator. Results: We found that burn insults caused typical ischemia and histological deterioration in the zone of stasis, in parallel with increases in oxidative stress and apoptosis. Mitochondrial damage was also involved in the aforementioned changes. Furthermore, we detected typical mitophagy in burn wounds, which was contradictory to the burn-wound conversion. HIF-1 expression was closely related to the level of mitophagy, while BNIP3 and PARKIN are involved downstream. Conclusion: We demonstrate that burn-induced mitochondrial impairment contributes to the mobilization of injurious mechanisms in the zone of stasis and that mitophagy provides a more bene cial way to protect against burn-wound progression via the elimination of damaged mitochondria. Our ndings offer insights into mitochondrial quality control in burn-wound progression and suggest the novel concept that HIF-1 may be a potential therapeutic target due to its possible regulatory effects upstream of BNIP3-or PARKIN-mediated mitophagy. Background Deep thermal burns can cause irreversible tissue damage to the integument that can further progress over 3 days[1]. Dynamic conversion, including expansion and deepening, can be observed in the peripheral zones of initial wounds of partial thickness or full thickness burns from 48 h to 72 h; this is de ned as burn wound progression[1-3]. Jackson described three concentric zones (coagulation, stasis and hyperemia from the center to the outer region) to explain the histopathological changes that occur in early burn wounds[4]. The intermediate zone, which undergoes stasis characterized by edema and slow blood ow, progresses to irrecoverable necrosis without appropriate interventions, and the zone of stasis is also considered salvageable and provides an opportunity to prevent cutaneous wound conversion after burn injury[1,2,5]. Efforts to attenuate the early deterioration of initial burn wounds are of great importance. The burn-induced ischemic status in the zone of stasis is attributed to multiple pathophysiological mechanisms, such as edema, vasoconstriction and hypercoagulability[2,5]. A number of studies have