Effects of Post-administration of β-Carotene on Diet-induced Atopic Dermatitis in Hairless Mice.

Atopic dermatitis (AD) is a cutaneous condition characterized by itchy, swollen, and dry skin, which is mediated by T helper cell-related cytokines. β-Carotene, a natural red pigment found in plants, exhibits antioxidant activity that has been shown to promote an inflammatory response. Because it is not clear whether β-carotene suppresses inflammation in AD skin tissues, we examined the effects of oral administration of β-carotene in mice induced by a low zinc/magnesium diet (HR-AD diet). Our studies found that AD-like inflammation was remarkably reduced by β-carotene. In addition, β-carotene significantly suppressed protein expression of TNF-α, IL-1β, and MCP-1 and mRNA expression of TSLP, IL-6, IL-1β, IL-4, IL-5, and Par-2 in AD-like skin tissues. It was also found that mRNA and protein expression of filaggrin (a major structural protein in epidermis) in AD-like skin was significantly elevated by β-carotene administration. Furthermore, β-carotene treatment significantly reduced the activity and/or mRNA expression of matrix metalloproteinases (MMPs), degradation of the extracellular matrix and regulation of chemokines. These results suggest that β-carotene reduces skin inflammation through the suppressed expression of inflammatory factors or the activity of MMPs as well as the promotion of filaggrin expression in AD-like skin. β-Carotene is a potent anti-inflammatory agent, which improves AD-like skin by enhancing the skin barrier function.