Comparative immunohistochemical assessment of cutaneous cyclooxygenase-2 enzyme expression in chronological aging and photoaging.

Background/purpose: Skin aging can be classified into chronological aging and photoaging. Cyclooxygenase-2 (COX-2) may be involved in ultraviolet-induced inflammation, photocarcinogenesis and the aging process. Studies done focused on assessing COX-2 expression after acute ultraviolet exposure and in photocarcinogenesis. Comparative assessment of COX-2 expression in chronological aging and photoaging was not previously studied. We aimed to compare COX-2 expression in chronological aging and photoaging.

Methods: Sixty participants were included (20 with chronological aging, 20 with photoaging, and 20 non-skin-aged contributors as controls). Fitzpatrick skin type and Glogau's photoaging type were assessed. Immunohistochemical evaluation of COX-2 was done in biopsies from sun-protected skin in the chronological aging and control groups, and from sun-exposed skin in the photoaging group.

Results: Comparison between each two groups showed a high statistically significant difference, with the highest percentage of mild, moderate and marked expression in the control, chronological aging and photoaging groups, respectively. A high statistically significant positive correlation was found between grading of solar elastosis in the photoaging group and COX-2 expression parameters.

Conclusion: COX-2 expression is significantly higher in chronologically aged and photoaged skin than the normal young skin. This level of expression is significantly higher in photoaging than in chronological aging. COX-2 expression is positively related with the degree of solar elastosis in photoaging.