Inflammatory mediators and inflammatory cells as reliable molecular targets for assessment of wound age and vitality in rats

Abstract

Evaluation of the wound age and vitality is a persistent problem for forensic examinations to determine when injuries occurred and whether during the antemortem or post-mortem period. This study aimed to use the inflammatory cells and mediators as a target marker to determine wound age in antemortem or post-mortem samples in rats. Wound skin samples (n=39) were collected from antemortem groups aged 30, 60, 180, and 360 min and post-mortem groups within the same periods with control samples (unwounded group). Immunohistochemical staining examined all tissue samples for two inflammatory cell markers (CD15, CD68) and 2 inflammatory mediators (IL-6, TNF-α). The results showed that CD15-positive neutrophils were expressed in all time intervals of antemortem, and the expression gradually increased from 30 to 360 min. The CD68-positive macrophages began at 30 minutes and reached the highest level at 360 minutes in the antemortem wound. Because of the negative expression of CD15 and CD68 in all post-mortem groups, they could be a marker for comparing the vital and non-vital wounds. Furthermore, the Immunoreactivity results showed that the IL-6 and TNF-α were negatively expressed in unwounded skin samples. In addition, the periods after the induced wound produced a rise in the expression area of both markers in antemortem wounds. In this study, IL-6 and TNF-α expressions were negative or low in areas far from wound margin, unwounded specimens, and post-mortem wounds. CD15, CD68, IL-6, and TNF-α may be valuable markers for assessing wound age and vitality.