Oral treatment with Aloe polysaccharide ameliorates ovalbumin-induced atopic dermatitis by restoring tight junctions in skin

Atopic dermatitis (AD) is a chronic inflammatory skin disease. A hallmark of AD is dry itchy skin that results from defects in the epidermal barrier function. Aloe vera is used widely to promote general health and is administered topically to treat skin conditions such as eczema, burns and wounds. However, effects of A vera on AD were not fully elucidated. In this study, we investigated the oral administration of processed A vera gel (PAG) containing low molecular weight Aloe polysaccharides to treat ovalbumin (OVA)-induced AD in mice. Oral administration of PAG suppressed total and OVA-specific IgE production in sera and decreased the epidermal thickness of skin. Numbers of Ki-67-positive cells were reduced by PAG treatment. Expression levels of tight junction genes, including those that encode ZO-1, Claudin-1 and Claudin-8, were decreased in AD skin lesions, whereas oral administration of PAG partially restored the expression levels of tight junction genes. In addition, IL-4 and IL-17A mRNA transcript levels were reduced in skin lesions after PAG treatment. Taken together, our findings suggest that oral administration of PAG ameliorated AD, normalized tight junction gene expression and suppressed inflammatory cytokines in AD skin.