Atopic dermatitis (AD) is an inflammatory skin disorder caused by genetic factors and immunological deficiency. Dryness, infectious agents such as bacteria, germs, and fungi, as well as environmental and psychological factors can contribute to AD, but...
Atopic dermatitis (AD) is an inflammatory skin disorder caused by genetic factors and immunological deficiency. Dryness, infectious agents such as bacteria, germs, and fungi, as well as environmental and psychological factors can contribute to AD, but the most direct causative factor has yet to be identified. In this study, I examined whether IL-6, IL-8, and MCP-1 protein expressions are increased by S100A8 and S100A9 treatment in HaCaT cells in time- and dose-dependent manners. Alterations of cytokine expression were examined by performing ELISA with various signal protein-specific inhibitors. Activation of the MAPK pathway and NF-κB was evaluated by using western blotting and NF- κB activity test. The expressions of IL-6, IL-8, and MCP-1 increased after treatment with S100A8 and S100A9, and the increase was significantly blocked by specific signal inhibitors such as TLR4i, rottlerin, PD98059, SB203580, and BAY-11-7085. Because these inhibitory effects indicate the association of ERK and p38 MAPK with S100A8 and S100A9 mechanisms, the activation of ERK and p38 MAPK was evaluated; both were activated in a time-dependent manner after treatment with S100A8 and S100A9. Phosphorylations of ERK and p38 MAPK were blocked by TLR4i and rottlerin. S100A8 and S100A9 induced translocation of NF- κB in a time-dependent manner, and the activation of NF- κB was inhibited by TLR4i, rottlerin, PD98059, SB203580, and BAY-11-7085. In addition, S100A8 and S100A9 decreased the expression of the skin barrier proteins filaggrin and loricrin. These results contribute to elucidating the pathogenic mechanism for AD and to developing strategies for controlling clinical features of AD.