title: Hydrangenol inhibits lipopolysaccharide-induced nitric oxide production in BV2 microglial cells by suppressing the NF-κB pathway and activating the Nrf2-mediated HO-1 pathway.
abstract: We previously demonstrated the anti-inflammatory effect of water extract of Hydrangea macrophylla in lipopolysaccharide (LPS)-stimulated macrophage cells. Here, we investigated whether hydrangenol, a bioactive component of H. macrophylla, attenuates the expression of nitric oxide (NO) and its associated gene, inducible NO synthase (iNOS), in LPS-stimulated BV2 microglial cells. Our data showed that low dosages of hydrangenol inhibited LPS-stimulated NO release and iNOS expression without any accompanying cytotoxicity. Hydrangenol also suppressed LPS-induced nuclear translocation of nuclear factor-κB (NF-κB) subunits, consequently inhibiting DNA-binding activity of NF-κB. Additionally, the NF-κB inhibitors, pyrrolidine dithiocarbamate (PDTC) and PS-1145, significantly attenuated LPS-induced iNOS expression, indicating that hydrangenol-induced NF-κB inhibition might be a key regulator of iNOS expression. Furthermore, our data showed that hydrangenol suppresses NO production by inducing heme oxygenase-1 (HO-1). The presence of cobalt protoporphyrin, a specific HO-1 inducer, potently suppressed LPS-induced NO production. Hydrangenol also promoted nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2) and subsequently increased its binding activity at the specific antioxidant response element sites. Additionally, transient knockdown of Nrf2 significantly downregulated hydrangenol-induced HO-1 expression, indicating that hydrangenol-induced Nrf2 is an upstream regulator of HO-1. Taken together, these data suggest that hydrangenol attenuates NO production and iNOS expression in LPS-stimulated BV2 microglial cells by inhibiting NF-κB activation and by stimulating the Nrf2-mediated HO-1 signaling pathway. Therefore, hydrangenol is a promising therapeutic agent for treatment of LPS-mediated inflammatory diseases.
authors.affiliation: Department of Marine Life Sciences, Jeju National University, Jeju 63243, Republic of Korea.
authors.forename: Hee-Ju
authors.initials: HJ
authors.lastname: Kim
authors.affiliation: Department of Marine Life Sciences, Jeju National University, Jeju 63243, Republic of Korea; Nakdonggang National Institute of Biological Resource, Sangju-si, Gyeongsangbuk-do 37242, Republic of Korea.
authors.forename: Chang-Hee
authors.initials: CH
authors.lastname: Kang
authors.affiliation: Department of Marine Life Sciences, Jeju National University, Jeju 63243, Republic of Korea.
authors.forename: Rajapaksha Gedara Prasad Tharanga
authors.initials: RGPT
authors.lastname: Jayasooriya
authors.affiliation: Department of Marine Life Sciences, Jeju National University, Jeju 63243, Republic of Korea.
authors.forename: Matharage Gayani
authors.initials: MG
authors.lastname: Dilshara
authors.affiliation: Department of Marine Life Sciences, Jeju National University, Jeju 63243, Republic of Korea.
authors.forename: Seungheon
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Biochemistry, College of Oriental Medicine, Dong-Eui University, Busan 47227, Republic of Korea.
authors.forename: Yung Hyun
authors.initials: YH
authors.lastname: Choi
authors.affiliation: Consilience Medical Center, Dankook University Hospital, Chungcheongnam-do 31116, Republic of Korea.
authors.forename: Yong Taek
authors.initials: YT
authors.lastname: Seo
authors.affiliation: Department of Marine Life Sciences, Jeju National University, Jeju 63243, Republic of Korea. Electronic address: immunkim@jejunu.ac.kr.
authors.forename: Gi-Young
authors.initials: GY
authors.lastname: Kim
mesh_terms: D000818:Animals; D002460:Cell Line; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000378:metabolism*; D029628:Hydrangeaceae / Q000276:immunology*; D007249:Inflammation / Q000188:drug therapy*; D049934:Isocoumarins / Q000494:pharmacology*; D008070:Lipopolysaccharides / Q000276:immunology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D017628:Microglia / Q000187:drug effects* / Q000276:immunology; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism*; D009569:Nitric Oxide / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D049934:Isocoumarins; D008070:Lipopolysaccharides; D008565:Membrane Proteins; D051267:NF-E2-Related Factor 2; D016328:NF-kappa B; C495636:Nfe2l2 protein, mouse; D034741:RNA, Small Interfering; D009569:Nitric Oxide; D052247:Nitric Oxide Synthase Type II; D051547:Heme Oxygenase-1; C496542:Hmox1 protein, mouse; C023818:hydrangenol
keywords: Heme oxygenase-1; Hydrangenol; Nitric oxide; Nuclear factor erythroid 2-related factor 2; Nuclear factor-κB