Anti-Inflammatory Activity ofHouttuynia cordataagainst Lipoteichoic Acid-Induced Inflammation in Human Dermal Fibroblasts

Houttuynia cordata (H. cordata) has anti-inflammatory and anti-bacterial activities. Staphylococcus aureus (S. aureus)-producing lipoteichoic acid (LTA) has been implicated in inflammatory and immunologic responses in patients with atopic dermatitis (AD). The purpose of this study was to determine the potential of H. cordata as a novel anti-inflammatory agent for AD by evaluating the anti-inflammatory activity of H. cordata water extract on LTA-induced inflammation in dermal fibroblasts (DFs). The anti-inflammatory activity of H. cordata was evaluated by studying the inflammatory markers tumor necrosis factor- α (TNF-α) and cyclooxygenase-2 (COX-2). As shown by MTT assay and COX-2 immunoblot, H. cordata was not toxic to DFs in doses up to 20μg/ml. In RT-PCR and Western blot analysis, LTA up-regulated TNF-α (mRNA) and COX-2 (protein) at doses of 5∼20μg/ml in a dose-dependent manner. Next, DFs were treated with LTA (10μg/ml) in the absence (control) or presence of H. cordata for 24 h. The level of LTA-induced TNF-α mRNA was suppressed by H. cordata (20μg/ml) by up to 40% compared with the level in LTA-treated control samples. Under the same conditions, the level of LTA-induced COX-2 protein was suppressed by H. cordata treatment by up to 52% compared with the level in LTA-treated control samples. When DFs were treated with TNF-α (10μg/ml) for 24 h, TNF-α-induced COX-2 expression was down-regulated by H. cordata treatment to 65% of that in control samples. In conclusion, H. cordata has anti-inflammatory activity against LTA-induced inflammation in DFs, in part by blocking the TNF-α pathway.