NF-κB and SIRT1 evaluation to discriminate antemortem from postmortem wounds. Potential markers of skin wound vitality in forensic practice

Background many studies have been conducted on wound age estimation, but to date no marker has been validated to use in routine forensic practice. To explore novel markers for vitality of wounds, we investigated the expression of the inflammatory-related marker nuclear factor kappa B (NF-κB) and analyzed its correlation with the silent information regulator sirtuin 1 (SIRT1) protein in skin wounds. Methods: on 8 amputated human limbs we collected human skin tissue samples from the amputation site, as antemortem samples, and from wounds produced on the stored corresponding limbs, as postmortem samples. Samples were processed for western blot and immunohistochemistry analysis to evaluate the ex-pression of NF-κB and SIRT1 proteins. Results: cytoplasmic and nuclear staining of NF-κB in epidermal cells of antemortem wounds was higher than in postmortem wounds, where the NF-κB signal was mainly localized in the nuclei of keratinocytes. Quantitative analysis demonstrated a 2-fold increase in NF-κB protein in antemortem wounds. On the contrary, SIRT-1 levels were almost absent in antemortem wounds, while high nuclear staining was detected in keratinocytes in postmortem wounds. Quantitative analysis of the stained area demonstrated a 3-fold increase in SIRT1 protein in postmortem wounds. Conclusions: analysis of NF-κB and SIRT1 showed a different qualitative and quantitative pattern of expression in antemortem and postmortem wounds. They represent good candidates as biomarkers in wound vitality estimation in forensic pathology eventually to include them in a panel of biomarkers.