HMGB1 release initiates burn wound healing delay via HMGB1-produced DNA gap reduction, promoting DNA damage-hypomethylation-senescence cascade

Burn wound healing is delayed due to a reduction in the epigenetic DNA protection marker, which promotes senescence. In the rat burn model, high mobility group box protein 1 (HMGB1)-produced DNA gap reduction induces DNA damage and impairs the wound-healing process. Overexpression of Box A, an HMGB1 domain, enhances DNA stability and promotes second-degree burn wound healing through the molecular process of DNA gap formation. However, the mechanisms responsible for HMGB1-produced DNA gap reduction in burn wounds remain unknown. In the cell culture model, we found that high temperatures stimulated the release of HMGB1 protein from the nucleus, resulting in a long-term decrease in DNA gaps. This reduction caused increased DNA damage, Alu hypomethylation, and eventual senescence, potentially limiting cutaneous wound healing processes. To reproduce DNA gaps, we applied exogenous Box A to transfect into burn wounds. In comparison to the other groups subjected to the same conditions, including no plasmid-treated group and plasmid control-treated group, the Alu methylation levels were significantly increased in the Box A-treated group. Meanwhile, a DNA damage marker (γH2A.X) and DNA damage response (DDR) signals (p53, p21, and p16) were all significantly decreased. As a result, reduced senescent cells and promoted cell proliferation, as well as accelerated wound confluence, all of which considerably improved wound healing in the group that received Box A treatment. Our findings revealed that HMGB1 release functions as an upstream mechanism in the molecular pathogenesis of burns, and Box A gene therapy could provide a targeted therapeutic strategy in burn wound treatment.