Effects of Dictamnus dasycarpus Turcz., root bark on ICAM-1 expression and chemokine productions in vivo and vitro study

Ethnopharmacological relevance The root bark of Dictamnus dasycarpus Turcz., family Rutaceae is a well known anti-inflammatory agent for skin diseases such as eczema, pruritus and urticaria in Eastern countries. Materials and methods We investigated the effects of methanol extract of Dictamnus dasycarpus root bark (MEDD) on Intercellular Adhesion Molecule-1 (ICAM-1) expression, epidermal hyperplasia and immune cell infiltration in 1-fluoro-2,4-dinitrofluorobenzene (DNFB)-induced contact dermatitis (CD) mice. We also investigated its effects on the expression of ICAM-1, binding capacity to THP-1 cells, cytokine and chemokine production, and phosphorylation of NF-κB in human keratinocytes (HaCaT cells). Results Topical application of MEDD effectively inhibited ICAM-1 expression and epidermal hyperplasia in inflamed tissues. MEDD treatment also inhibited immune cell infiltration induced by DNFB. In addition, treatment with MEDD reduced surface expression and total amount of ICAM-1in HaCaT cells and effectively lowered the capacity to bind to THP-1 cells. MEDD also lowered the levels of IL-6, IL-8, monokine induced by gamma interferon (MIG), monocyte chemotactic protein-1 (MCP-1) and regulated on activation, normal T cell expressed and secreted (RANTES). Finally, MEDD treatment prevented activation of the NF-κB pathway induced by TNF-α in HaCaT cells. Conclusions These data indicate that root bark of Dictamnus dasycarpus has the potential for treatment of inflammatory skin diseases as a complementary or alternative medicine to corticosteroids. In addition, they suggest that the anti-inflammatory effects of Dictamnus dasycarpus on CD are involved in the regulation of ICAM-1 expression and cytokine and chemokine secretion through down-regulation of the NF-κB signaling pathway in keratinocytes.