KCHO-1, a Novel Antineuroinflammatory Agent, Inhibits Lipopolysaccharide-Induced Neuroinflammatory Responses through Nrf2-Mediated Heme Oxygenase-1 Expression in Mouse BV2 Microglia Cells

The brain is vulnerable to oxidative stress and inflammation that can occur as a result of aging or neurodegenerative diseases. Our work has sought to identify natural products that regulate heme oxygenase (HO)-1 and to determine their mechanism of action in neurodegenerative diseases. KCHO-1 is a novel herbal therapeutic containing 30% ethanol (EtOH) extracts from nine plants. In this study, we investigated the antineuroinflammatory effects of KCHO-1 in lipopolysaccharide-(LPS-) treated mouse BV2 microglia. KCHO-1 inhibited the protein expression of inducible nitric oxide synthase (iNOS), iNOS-derived nitric oxide (NO), cyclooxygenase-(COX-) 2, and COX-2-derived prostaglandin E2 (PGE(2)) in LPS-stimulated BV2 microglia. It also reduced tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and IL-6 production. This effect was correlated with the suppression of inhibitor of nuclear factor kappa B-alpha (I kappa B-alpha) phosphorylation and degradation and nuclear factor kappa B (NF-kappa B) translocation and DNA binding. Additionally, KCHO-1 upregulatedHO-1 expression by promoting nuclear translocation of nuclear factor E2-related factor 2 (Nrf2) in mouse BV2 microglia. Tin protoporphyrin (SnPP), an HO activity inhibitor, was used to verify the inhibitory effects of KCHO-1 on proinflammatory mediators and proteins associated with HO-1 expression. Our data suggest that KCHO-1 has therapeutic potential in neurodegenerative diseases caused by neuroinflammation.