title: Placental expression of proBNP/NT-proBNP and plasma levels of NT-proBNP in early- and late-onset preeclampsia.
abstract: BACKGROUND
  Levels of plasma N-terminal pro B-type natriuretic peptide (NT-proBNP) are elevated in preeclampsia. In this study, the possibility that the placenta produces and releases proBNP/NT-proBNP was explored. Plasma levels of NT-proBNP in early- and late-onset preeclampsia were also measured.
  
  
  METHODS
  Placental proBNP mRNA in early-onset preeclampsia (n = 7), late-onset preeclampsia (n = 8), and controls of similar gestational age (n = 10) was assessed by quantitative real-time polymerase chain reaction. ProBNP/NT-proBNP protein was studied in placental samples with immunohistochemistry (n = 8) and tissue culture (n = 2). Plasma levels of NT-proBNP were measured in early-onset preeclampsia (n = 18), late-onset preeclampsia (n = 20), and relevant controls (n = 36).
  
  
  RESULTS
  Transcripts of proBNP mRNA were found in 20 out of 25 samples, there were no differences in expression between the groups. ProBNP/NT-proBNP protein was observed in maternal spiral arteries and in syncytiotrophoblasts in all placental samples. After placental tissue culture, there were measurable amounts of NT-proBNP in the culture media. Women with both early- (365 [14-9815] pg/ml) and late-onset preeclampsia (176 [33-2547] pg/ml) had higher levels of NT-proBNP than their controls (P < 0.001). There was a tendency toward higher levels of NT-proBNP in women with early-onset preeclampsia than in women with late-onset preeclampsia (P = 0.057).
  
  
  CONCLUSIONS
  The results indicate possible placental production and release of proBNP/NT-proBNP into the maternal circulation.
authors.affiliation: Department of Women's and Children's Health, Uppsala University, Uppsala, Sweden; katja.junus@kbh.uu.se.
authors.forename: Katja
authors.initials: K
authors.lastname: Junus
authors.affiliation: Department of Women's and Children's Health, Uppsala University, Uppsala, Sweden;
authors.forename: Anna-Karin
authors.initials: AK
authors.lastname: Wikström
authors.affiliation: Department of Medical Sciences, Biochemical Structure and Function, Uppsala University, Uppsala, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Larsson
authors.affiliation: Department of Women's and Children's Health, Uppsala University, Uppsala, Sweden;
authors.forename: Matts
authors.initials: M
authors.lastname: Olovsson
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005819:Genetic Markers; D005865:Gestational Age; D006801:Humans; D007150:Immunohistochemistry; D020097:Natriuretic Peptide, Brain / Q000097:blood* / Q000235:genetics* / Q000378:metabolism; D010446:Peptide Fragments / Q000097:blood* / Q000235:genetics* / Q000378:metabolism; D010920:Placenta / Q000378:metabolism*; D011225:Pre-Eclampsia / Q000097:blood* / Q000235:genetics* / Q000503:physiopathology; D011247:Pregnancy; D011498:Protein Precursors / Q000097:blood* / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000097:blood*; D060888:Real-Time Polymerase Chain Reaction; D046509:Tissue Culture Techniques; D015854:Up-Regulation; D055815:Young Adult
chemical_list: D005819:Genetic Markers; D010446:Peptide Fragments; D011498:Protein Precursors; D012333:RNA, Messenger; C109794:pro-brain natriuretic peptide (1-76); D020097:Natriuretic Peptide, Brain
keywords: B-type natriuretic peptide; NT-proBNP; blood pressure; early-onset preeclampsia; hypertension; late-onset preeclampsia; placenta.