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

Summary 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.