Effects of β‐carotene on oxazolone‐induced atopic dermatitis in hairless mice

Skin acts as a barrier, which protects internal tissues and promotes moisture retention. Atopic dermatitis (AD) is an inflammatory skin disease associated with a variety of genetic and environmental factors that involve helper T cells. β-Carotene (provitamin A) exhibits antioxidant activity and activates the immune system. However, it is not clear whether inflammation in AD skin is improved by posttreatment with β-carotene. In the current study, we investigated the effects of β-carotene on the skin of hairless mice with oxazolone-induced inflammation/oedema (Ox-AD mice). We found that skin inflammation was significantly reduced by oral administration of β-carotene. In addition, treatment with β-carotene suppressed protein levels of TNF-α, IL-1β and MCP-1, as well as mRNA expression associated with IL-1β, IL-6, IL-4 and Par-2 in skin tissues. Furthermore, the mRNA and protein levels of filaggrin, a structural protein in the epidermal stratum corneum, were elevated by β-carotene administration as compared with Ox-AD mice. β-Carotene significantly reduced the activity of proMMP-9, but not proMMP-2. These results suggest that in Ox-AD mice, β-carotene improves skin inflammation by suppressing the expression of inflammatory factors, promoting filaggrin expression and reducing MMP-9 activity. β-Carotene is a potent anti-inflammatory agent that improves the barrier functions of AD skin.