Abstract: Atopic dermatitis (AD) is a biphasic inflammatory skin disease that is provoked by
epidermal barrier defects, immune dysregulation, and increased skin infections. Previously, we have
demonstrated that bvPLA2 evoked immune tolerance by inducing regulatory T cells (Treg), and thus
alleviated Th2 dominant allergic asthma in mice. Here, we would like to determine whether treatment
with bvPLA2 exacerbates the AD-like allergic inflammations induced by house dust mite extract
(DFE) in a murine model. Epidermal thickness, immune cell infiltration, serum immunoglobulin,
and cytokines were measured. Ear swelling, skin lesions, and the levels of total serum IgE and
Th1/Th2 cytokines were elevated in DFE/DNCB-induced AD mice. Topical application of bvPLA2
elicited significant suppression of the increased AD symptoms, including ear thickness, serum IgE
concentration, inflammatory cytokines, and histological changes. Furthermore, bvPLA2 treatment
inhibited mast cell infiltration into the ear. On the other hand, Treg cell depletion abolished the
anti-atopic effects of bvPLA2, suggesting that the effects of bvPLA2 depend on the existence of
Tregs. Taken together, the results revealed that topical exposure to bvPLA2 aggravated atopic skin
inflammation, suggesting that bvPLA2 might be a candidate for the treatment of AD.