Abstract

Purpose

Dihydroxyacetone (DHA) is the only ingredient approved by the U.S. FDA as a colour additive in sunless tanning (self-tanning) products. Consumer sunless tanning products available for retail purchase contain 1–15% DHA. Although originally thought to only interact with the stratum corneum, more recent research has shown that DHA penetrates beyond the stratum corneum to living keratinocytes indicating a possible route of exposure in the epidermis.

Materials and methods

Normal Human Epidermal Keratinocytes (NHEK) were used to determine any potential in vitro toxicological effects of DHA in the epidermis. NHEK cells exposed to DHA concentrations up to 0.90% (100 mM) in dosing media were evaluated for viability, genotoxicity (Comet Assay), and gene expression changes by microarray analysis.

Results

Cell viability significantly decreased ∼50% after 3-h exposure to 50 and 100 mM DHA. DNA damage was only found to be significantly increased in cells exposed to cytotoxic DHA concentrations. A subtoxic dose of DHA induced significant gene expression changes. Particularly, expression of cyclin B1, CDK1, and six other genes associated with the G2/M cell cycle checkpoint was significantly decreased which correlates well with a G2/M block reported in the existing literature. Advanced Glycation End Product (AGE) formation significantly increased after 24 h of DHA exposure at and above 10 mM. In summary, these data show that DHA is cytotoxic above 25 mM in primary keratinocytes. Genotoxicity was detected only at cytotoxic concentrations, likely indicative of non-biologically relevant DNA damage, while subtoxic doses induce gene expression changes and glycation.

Conclusion

DHA treatment had a significant and negative effect on primary keratinocytes consistent with in vitro cultured cell outcomes; however, more information is needed to draw conclusions about the biological effect of DHA in human skin.

中文翻译：

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二羟基丙酮在人原代角质形成细胞中的细胞毒性、基因毒性和毒性基因组学效应

摘要

目的

二羟基丙酮 (DHA) 是唯一被美国 FDA 批准作为免晒美黑（自晒黑）产品的颜色添加剂的成分。可供零售的消费者免晒美黑产品含有 1-15% DHA。虽然最初被认为只与角质层相互作用，但最近的研究表明，DHA 可以穿透角质层到达活的角质形成细胞，表明可能的暴露途径是表皮。

材料和方法

正常人表皮角质形成细胞 (NHEK) 用于确定DHA 在表皮中的任何潜在体外毒理学作用。通过微阵列分析评估了暴露于剂量培养基中 DHA 浓度高达 0.90% (100 mM) 的 NHEK 细胞的活力、基因毒性（彗星测定）和基因表达变化。

结果

暴露于 50 和 100 mM DHA 3 小时后，细胞活力显着降低了约 50%。仅发现暴露于细胞毒性 DHA 浓度的细胞中 DNA 损伤显着增加。亚毒性剂量的 DHA 诱导显着的基因表达变化。特别是，与 G2/M 细胞周期检查点相关的 cyclin B1、CDK1 和其他六种基因的表达显着降低，这与现有文献中报道的 G2/M 阻滞密切相关。在 10 mM 及以上的 DHA 暴露 24 小时后，高级糖基化终产物 (AGE) 的形成显着增加。总之，这些数据表明 DHA 在原代角质形成细胞中具有高于 25 mM 的细胞毒性。仅在细胞毒性浓度下检测到基因毒性，可能表明非生物学相关的 DNA 损伤，

结论

DHA 治疗对原代角质形成细胞有显着的负面影响，这与体外培养的细胞结果一致；然而，需要更多的信息来得出关于 DHA 在人体皮肤中的生物学效应的结论。