Certain cosmetic colorants are irritant to skin or aggravate dermatitis. Thymic stromal lymphopoietin (TSLP) plays an important role in the initiation and progress of skin inflammation and atopic dermatitis by triggering Th2 immune responses. However, the effects of cosmetic colorants on TSLP production are unknown yet. Therefore, we investigated whether cosmetic colorants regulated TSLP production and dermatitis. Lithol Rubine B (LR-B, Pigment Red 57) and its calcium salt (LR-BCA), commonly used cosmetic colorants, potentiated phorbol-12-myristate-13-acetate-induced TSLP production in keratinocytes. In addition, the topical exposure to LR-B or LR-BCA on mouse ear upregulated a TSLP inducer (MC903)-induced TSLP production and Th2 cytokine expression. Dermatitis symptoms and serum IgE and histamine levels were also aggravated by LR-B or LR-BCA, implicating the role of increased TSLP expression in acute dermatitis. LR-B or LR-BCA induced IκBα degradation and NF-κB activation in keratinocytes, leading to TSLP expression. Collectively, our results demonstrate that LR-B and LR-BCA increase TSLP expression and Th2 immune responses, thereby aggravating acute dermatitis in the compromised skin. The results further suggest that certain cosmetic colorants such as LR-B may aggravate dermatitis under pro-inflammatory conditions by upregulating TSLP production.

某些化妆品着色剂对皮肤有刺激性或加重皮炎。胸腺基质淋巴细胞生成素（TSLP）通过触发Th2免疫反应，在皮肤炎症和特应性皮炎的发生和发展中起重要作用。然而，尚不清楚化妆品着色剂对TSLP生产的影响。因此，我们调查了化妆品着色剂是否能调节TSLP的产生和皮炎。常用的化妆品着色剂Lithol Rubine B（LR-B，颜料红57）及其钙盐（LR-BCA）增强了佛波醇12-肉豆蔻酸酯13-乙酸酯诱导的角质形成细胞TSLP生成。此外，小鼠耳局部暴露于LR-B或LR-BCA会上调TSLP诱导剂（MC903）诱导的TSLP产生和Th2细胞因子的表达。LR-B或LR-BCA也加剧了皮炎症状，血清IgE和组胺水平，提示增加TSLP表达在急性皮炎中的作用。LR-B或LR-BCA诱导角质形成细胞中IκBα降解和NF-κB活化，从而导致TSLP表达。总的来说，我们的结果表明LR-B和LR-BCA会增加TSLP表达和Th2免疫反应，从而加剧受损皮肤的急性皮炎。结果进一步表明，某些化妆品着色剂（例如LR-B）在炎性条件下可通过上调TSLP产生而加重皮炎。