title: Downregulation of angiotensin converting enzyme by TNF-alpha in differentiating human macrophages.
abstract: OBJECTIVE
  To investigate regulation of angiotensin converting enzyme (ACE) by tumour necrosis factor alpha (TNF-alpha) in differentiating human peripheral blood monocytes (PBM).
  
  
  METHODS
  Human PBM were allowed to differentiate to macrophages for 0-7 days and ACE amount was measured during differentiation. Experiments with TNF-alpha were performed after 2 days of differentiation. Cell cultures were incubated with TNF-alpha (0.5-10ng/ml) without or with SB 202190 (5microM), or PD 98059 (40microM). ACE amounts were measured by an inhibitor binding assay (IBA) and ACE mRNA levels by RNase protection assay (RPA). Activated p44/42 and p38 MAP kinases were measured by Western Blot analysis using phospho-p44/42 and -p38 MAPK antibodies.
  
  
  RESULTS
  ACE amount increased by 40-fold along with macrophage differentiation. TNF-alpha caused dose dependent suppression of the amount of ACE and decreased levels of ACE mRNA. TNF-alpha activated p44/42 and p38 MAP kinases, which was inhibited by the specific inhibitors of these kinases, PD98059 or SB202190, respectively. Pretreatment of the cells with SB 202190, or PD 98059 both partly reversed TNF-alpha induced ACE suppression.
  
  
  CONCLUSIONS
  TNF-alpha downregulated ACE, which effect was probably mediated by both p44/42 and p38 MAPK pathways. Local downregulation of ACE by TNF-alpha may be a counterbalancing mechanism in inflammatory processes.
authors.affiliation: Minerva Institute for Medical Research, Helsinki, Finland.
authors.forename: Anna
authors.initials: A
authors.lastname: Viinikainen
authors.forename: Tuulikki
authors.initials: T
authors.lastname: Nyman
authors.forename: Frej
authors.initials: F
authors.lastname: Fyhrquist
authors.forename: Outi
authors.initials: O
authors.lastname: Saijonmaa
mesh_terms: D015153:Blotting, Western; D002454:Cell Differentiation; D002465:Cell Movement; D002478:Cells, Cultured; D015536:Down-Regulation; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D015151:Immunoblotting; D008264:Macrophages / Q000166:cytology* / Q000378:metabolism*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism*; D010766:Phosphorylation; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*; D048051:p38 Mitogen-Activated Protein Kinases
chemical_list: D004791:Enzyme Inhibitors; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D007703:Peptidyl-Dipeptidase A