Abstract
In most cases, atopic dermatitis (AD) is induced by allergic inflammation, with antigen penetration into the epithelial tissues of the skin being the first step in AD development. Accordingly, inhibiting the skin penetration of antigens is effective in preventing AD. We evaluated the ability of the following four types of particles to adsorb ovalbumin (OVA): titanium dioxide (TiO(2)), silicon dioxide (SiO(2)), carbon, and SiO(2) coated with one-layer graphene (1LGCS). We found that metal oxide particles (TiO(2) and SiO(2)) could adsorb OVA at pH 5.0, but their abilities decreased at pH 7.0 and 9.0. In contrast, the carbon-based particles (carbon and 1LGCS) adsorbed OVA regardless of pH changes. Epicutaneous treatment with OVA resulted in an increase in the proportion of OVA-positive Langerhans cells and dermal dendritic cells in the lymph nodes, along with elevated interleukin-4 mRNA expression, indicating that OVA penetrated the epidermis and underlying tissues. When OVA was applied together with the particles, these responses were significantly reduced by the carbon-based particles but were only partially or not inhibited by metal oxide particles. These findings indicated that antigen penetration was potently inhibited by the carbon-based particles. Additionally, when mice were epicutaneously sensitised and challenged with OVA in the presence of carbon, the increase in OVA-specific IgG1 and IgE levels was significantly inhibited. The efficiency of carbon-based particles may be attributed to their stable adsorption of proteins despite pH changes on the skin surface. These findings may lead to the development of new treatments for AD with fewer side effects.