title: Fulvic acid attenuates homocysteine-induced cyclooxygenase-2 expression in human monocytes.
abstract: BACKGROUND
  Homocysteine and pro-inflammatory mediators such as cyclooxygenase-2 (COX-2) have been linked to vascular dysfunction and risks of cardiovascular diseases. Fulvic acid (FA), a class of compounds of humic substances, possesses various pharmacological properties. However, the effect of FA on inflammatory responses of the monocytes remains unclear. We investigated the regulatory effect of FA on homocysteine-induced COX-2 expression in human monocytes.
  
  
  METHODS
  Peripheral blood monocytes and U937 cells were used for all experiments. Real-time PCR and ELISA assay were used to analyze the COX-2 mRNA expression and PGE2 secretion, respectively. Specific inhibitors were used to investigate the mechanism of homocysteine-mediating COX-2 mRNA expression and PGE2 secretion. Luciferase assay, transcription factor ELISA, and chromatin immunoprecipitation were used to determine the role of nuclear factor-κB in FA-mediated inhibition of homocysteine effect on monocytes.
  
  
  RESULTS
  The results show that pretreating monocytes with FA inhibited the homocysteine-induced COX-2 expression in a dose-dependent manner. Stimulation of U937 monocytes with homocysteine induced rapid increases in the phosphorylation of ERK and JNK; the inhibitor for ERK and JNK attenuated the homocysteine-induced nuclear factor-κB activation and COX-2 expression. Transcription factor ELISA and chromatin immunoprecipitation assays showed that FA blocked the homocysteine-induced increases in the binding activity and in vivo promoter binding of nuclear factor-κB in monocytes.
  
  
  CONCLUSIONS
  Our findings provide a molecular mechanism by which FA inhibits homocysteine-induced COX-2 expression in monocytes, and a basis for using FA in pharmaceutical therapy against inflammation.
authors.affiliation: Division of Pediatric Cardiology, Department of Pediatrics, Kaohsiung Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Kaohsiung, Taiwan. csjdc@adm.cgmh.org.tw.
authors.forename: Shao-Ju
authors.initials: SJ
authors.lastname: Chien
authors.affiliation: Division of Nephrology, Kaohsiung Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Kaohsiung, Taiwan. ma4671@gmail.com.
authors.forename: Te-Chuan
authors.initials: TC
authors.lastname: Chen
authors.affiliation: Institute of Nursing and Department of Nursing, Chang Gung University of Science and Technology, Taoyuan, Taiwan. kuohc@gw.cgust.edu.tw.|Chronic Diseases and Health Promotion Research Center, Chang Gung University of Science and Technology, Taoyuan, Taiwan. kuohc@gw.cgust.edu.tw.|Research Center for Industry of Human Ecology, Chang Gung University of Science and Technology, Taoyuan, Taiwan. kuohc@gw.cgust.edu.tw.
authors.forename: Hsing-Chun
authors.initials: HC
authors.lastname: Kuo
authors.affiliation: Department of Biochemical Science and Technology, National Chiayi University, Chiayi, 600, Taiwan. cnchen@mail.ncyu.edu.tw.
authors.forename: Cheng-Nan
authors.initials: CN
authors.lastname: Chen
authors.affiliation: Biophotonics and Molecular Imaging Research Center, National Yang Ming University, No. 155, Sec. 2, Linong St. Beitou District, Taipei, Taiwan. sfc0415@ym.edu.tw.
authors.forename: Shun-Fu
authors.initials: SF
authors.lastname: Chang
mesh_terms: D001578:Benzopyrans / Q000494:pharmacology / Q000627:therapeutic use*; D002460:Cell Line; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D052246:Cyclooxygenase 2 Inhibitors / Q000494:pharmacology / Q000627:therapeutic use*; D005786:Gene Expression Regulation / Q000187:drug effects*; D006710:Homocysteine / Q000378:metabolism*; D006801:Humans; D007249:Inflammation / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D009000:Monocytes / Q000187:drug effects* / Q000378:metabolism; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism
chemical_list: D001578:Benzopyrans; D052246:Cyclooxygenase 2 Inhibitors; D016328:NF-kappa B; D012333:RNA, Messenger; D014157:Transcription Factors; D006710:Homocysteine; D051546:Cyclooxygenase 2; C005023:fulvic acid