Supplementary Material for: Dehydroabietic Acid Induces Regeneration of Collagen Fibers in Ultraviolet B-Irradiated Human Dermal Fibroblasts and Skin Equivalents

Background/Aims: Dehydroabietic acid (DAA) is a natural phytochemical found in red pine trees and herbal plants. While DAA and its derivatives are known for improving diabetes and hyperlipidemia, the antiaging effect and its underlying mechanisms of DAA on skin have not been fully examined. Here, we assessed the antiaging effects of DAA on human dermal fibroblasts and skin equivalents. Methods: We investigated the effect of DAA on the secretion of type I procollagen and matrix metalloproteinase-1 (MMP-1) in ultraviolet B (UVB)-irradiated neonatal normal human dermal fibroblasts (NHDFn). Using nonlinear optical imaging techniques, we visualized quantitative and qualitative changes of collagen fibers by DAA treatment in human skin equivalent models. Results: DAA induces increases in type I procollagen secretion when treated on UVB-irradiated NHDFn. DAA also downregulates secretion of MMP-1 through the inhibition of the JNK signaling pathway. In human skin equivalent models, we successfully visualized the spatial distribution of collagen fibers in the dermis and found that quantity, diameter, and arrangement of collagen fibers in the dermis were significantly improved by DAA treatment. Conclusion: Our results suggest that DAA could be a useful agent for improving skin photoaging through the protection and regeneration of collagen fibers in skin.研究背景与目的：脱氢枞酸（Dehydroabietic acid, DAA）是一种存在于红松及药用植物中的天然植物化学物。尽管DAA及其衍生物已被证实可改善糖尿病与高脂血症，但其对皮肤的抗衰作用及潜在作用机制尚未得到充分探究。本研究旨在评估DAA对人类真皮成纤维细胞及皮肤等效模型的抗衰效果。 研究方法：本研究考察了DAA对紫外线B（UVB）照射的新生儿正常人类真皮成纤维细胞（NHDFn）中I型前胶原与基质金属蛋白酶-1（MMP-1）分泌水平的影响。借助非线性光学成像技术，我们对人类皮肤等效模型中经DAA处理后的胶原纤维的数量与质量变化进行了可视化观测。 研究结果：DAA可促进经UVB照射的NHDFn分泌I型前胶原。同时，DAA可通过抑制JNK信号通路下调MMP-1的分泌。在人类皮肤等效模型中，我们成功可视化了真皮胶原纤维的空间分布，并发现DAA处理可显著改善真皮胶原纤维的数量、直径及排列状态。 研究结论：本研究结果表明，DAA可通过保护并再生皮肤中的胶原纤维，成为改善皮肤光老化的潜在有效制剂。