Anti‑inflammation activity of brazilin in TNF‑α induced human psoriasis dermatitis skin model

Abstract

Psoriasis is a chronic inflammatory skin disease that causes erythema, scale, and invasion due to excessive proliferation of keratinocyte and vascular deformation of the upper part of the dermis. Recently, it has been reported that brazilin, an active compound of Caesalpinia sappan L., possesses anti-inflammatory activity in mouse macrophage. However, little is known about its effect or anti-inflammatory activity on psoriasis dermatitis. Thus, the objective of this study was to determine anti-inflammatory activity of brazilin in TNF-α-induced human keratinocyte (HaCaT) widely used as a model of psoriatic dermatitis. First, CCK-8 assay was performed to determine cytotoxicity of brazilin in HaCaT cells and cytotoxicity was not observed up to 7 μg/mL concentrations. Brazilin decreased mRNA expression levels of inflammatory cytokines such as IL-1α, IL-1β, IL-6, IL-8 and TNF-α in a concentration dependent manner. Brazilin also significantly reduced phosphorylation of I-κB, Akt, and MAPKs such as ERK, JNK, p38 and STAT3 in immortalized human keratinocytes (HaCaT) induced by TNF-α. In addition, inflammation causes the weakness of the skin barrier structure and increase cell permeability, stimulating serious problems in skin moisturizing. Thus, we observed changes of skin permeability in TNF-α induced inflammatory condition through transepithelial electrical resistance (TEER) assay. While TNF-α induced inflammation caused reduction of TEER value (ohm (Ω) × cm2), it was recovered by treatment with brazilin in a concentration-dependent manner. These results strongly imply that brazilin can reinforcethe skin barrier due to its anti-inflammatory activity. Therefore, brazilin could be a promising candidate for treating psoriasis dermatitis.