Juzen-taiho-to, an herbal medicine, activates and enhances phagocytosis in microglia/macrophages.

Microglia are the main resident immunocompetent and phagocytic cells in the central nervous system (CNS). Activated microglia could play phagocytic roles as well as mediate inflammatory processes in the CNS. Involvement of activated microglia in the pathogenesis has been demonstrated in several neurological diseases including Alzheimer's disease (AD). Juzen-taiho-to (JTT), a traditional herbal medicine, has been reported to have effects on activating immune responses and phagocytosis. So far, little is known about the effects of this Kampo formulation JTT on microglia and in AD. In this report, we studied the effects of JTT on the activation and phagocytic functions of mouse microglia and bone marrow-derived macrophages (BMM). JTT could activate microglia, which was confirmed by the prominent morphological change and increased surface expression of an activation marker CD11b. In addition, JTT was revealed to induce microglial proliferation, and enhance microglial phagocytosis of, without eliciting an excessive production of nitric oxide. Furthermore, when mice were administrated with JTT in vivo, their BMM showed more effective phagocytosis of fibrillar Abeta(1-42). These findings implicate the therapeutic potential of JTT in AD and other neurological diseases accompanied by microglial activation.