The correlation between skin wound age and expression of IL-36α, IL-36γ and IL-38 proteins in mice.

PURPOSE: To investigate the time-dependent expression of inflammatory cytokines (IL-36α, IL-36γ, and IL-38) in mouse skin wounds and explore their forensic potentials in wound age estimation.

METHODS

A standardized skin wound model in mice at seven time points (6 h, 12 h, 1d, 3d, 5d, 7d, and 10d) was established. The protein and mRNA expression levels of IL-36α, IL-36γ, and IL-38 were measured by Western blot and RT-qPCR. Finally, three mathematical models of IL-36α, IL-36γ, and IL-38 based on the protein levels of skin wounds were constructed.

RESULTS

Morphological changes were aligned with the alterations noted in traditional skin wounds. The expression of IL-36α and IL-36γ proteins gradually increased and then decreased over a period of six hours to the fifth day, whereas the peak level for IL-38 protein was achieved on the third day. IL-38 demonstrated the strongest correlation with wound age (R2 = 0.9484), followed by IL-36γ (R2 = 0.8743) and IL-36α (R2 = 0.8297). Additionally, the regression analysis revealed distinct temporal expression patterns for each protein. IL-36α: y = (3E-06)x3-0.0014 x2 + 0.1637x + 1.3255; IL-36γ: y = (-7E-09)x4 + (6E-06)x3-0.0017x2 + 0.1833x + 1.0132; IL-38: y = (-1E-08)x4 + (1E-05)x3-0.0026x2 + 0.2298x + 0.6899.

CONCLUSION

The expression changes of IL-36α, IL-36γ, and IL-38 are time-dependent after skin injury and may serve as supplementary indicators to wound age estimation.