The expression of mRNA of proinflammatory cytokines during skin wound healing in mice: a preliminary study for forensic wound age estimation (II)

This study examined the temporal expression of mRNA for the proinflammatory cytokines, interleukin (IL)-1 alpha, IL-1 beta, IL-6 and tumor necrosis factor-alpha (TNF alpha) in incised wounds in mice using the reverse transcriptase-polymerase chain reaction (RT-PCR) and in situ hybridization (ISH) techniques. After incision, an increase in each cytokine mRNA level was observed by RT-PCR. The local IL-6 mRNA level peaked at 6 h, while the peak levels of mRNA for IL-1 alpha, IL-1 beta and TNF alpha occurred between 48 and 72 h. All cytokine mRNA levels were almost normalized after 240 h. In the early phase of wound healing, infiltrating polymorphonuclear cells were labeled with antisense probes for IL-1 alpha, IL-1 beta and TNF alpha mRNA by the ISH technique. Thereafter. infiltrating mononuclear cells and spindle-shaped mesenchymal cells showed positive signals for all the cytokines examined. Regenerating epidermal cells were also labeled with the antisense probes for IL-1 alpha, IL-6 and TNF alpha mRNA, indicating that IL-1, IL-6, and TNFa are involved in skin wound healing and their local production by various cells involved in the healing process is suggested. From the viewpoint of forensic pathology, the temporal characteristics of the cytokine mRNA expression may have a potential to indicate wound age or wound vitality.