Effect of keigai-rengyo-to, a Japanese kampo medicine, on neutrophil functions: A possible mechanism of action of keigai-rengyo-to in acne

On the basis of recent reports that keigai-rengyo-to (TJ-50), an oral Japanese Kampo (herb) medicine, is clinically effective in treating acne, and that tetracyclines are effective against acne by acting directly as an antioxidant on infiltrated neutrophils, we investigated the effect of TJ-50 on the generation of reactive oxygen species (ROS), using human neutrophils and a cell-free, xanthine-xanthine oxidase system. The species investigated were superoxide radical anion (O₂^-), hydrogen peroxide (H₂O₂), and hydroxyl radical (OH·). In addition, neutrophil chemotaxis, phagocytosis and calcium concentration, [Ca²⁺]i in neutrophils were also assessed. TJ-50 significantly decreased neutrophil-generated O₂^-, H₂O₂, and OH· in a dose-dependent manner. Three kinds of ROS generated in the cell-free system were also reduced in the presence of TJ-50. On the other hand, the medicine did not markedly affect neutrophil chemotaxis, phagocytosis or [Ca²⁺]i in neutrophils. Our results indicate that the clinical effectiveness of TJ-50 in the treatment of acne may be due partly to its antioxidant action on infiltrated neutrophils.