Impact of Thermal Injury on Wound Infiltration and the Dermal Inflammatory Response1

Healing of the burn wound is a critical component of the burn patient's successful recovery. While inflammation is a critical component of the healing process, it is unknown whether the inflammatory response differs between non-burn and burn wounds. To study this, mice were subjected to major burn injury or sham procedure. Wound cells were collected by implantation of polyvinyl alcohol sponges beneath the burn site in injured mice or beneath uninjured skin in sham mice (i.e., non-burn wound). Three days thereafter, skin, wound fluid, and infiltrating cells were collected for analysis. Significant levels of tumor necrosis factor (TNF)-α, interleukin (IL-6), monocyte chemoattractant protein (MCP)-1, and keratinocyte-derived chemokine (KC) were observed in burn wound tissue and the wound fluid from both non-burn and burn wounds. Burn injury induced 3-fold higher levels of KC and 50-fold higher levels of IL-6 in the wound fluid compared with non-burn injury. Significant numbers of the cells from both burn and non-burn wounds were CD11b+, GR1+, and F4/80+, suggestive of a myeloid suppressor cell phenotype, whereas CD3+ T-cells were negligible under both conditions. LPS induced TNF-α, IL-6, IL-10, MCP-1, KC, and nitric oxide production in both cell populations, however, IL-6, IL-10, MCP-1, and KC levels were suppressed in burn wound cell cultures. These findings indicate that significant differences in the wound inflammatory response exist between burn and non-burn cutaneous wounds and that the unique characteristics of the inflammatory response at the burn site may be an important contributing factor to post-burn wound healing complications.