title: Pregnancy and preeclampsia affect monocyte subsets in humans and rats.
abstract: BACKGROUND
  Both nonclassical and intermediate monocytes have been implicated in different inflammatory conditions. We hypothesized that these monocytes would increase during pregnancy, a condition associated with generalized activation of inflammatory responses and that they would increase even more during preeclampsia, in which inflammatory responses are further stimulated. In the present study we investigated changes in monocyte subsets during healthy pregnancy and preeclampsia in humans and rats.
  
  
  METHODS
  Blood monocyte subsets of nonpregnant, preeclamptic and healthy pregnant women were identified with CD14 and CD16. In nonpregnant and pregnant rats, blood monocytes were identified with CD172a and CD43, as well as in rats infused with adenosine triphosphate (ATP), a pro-inflammatory stimulus known to induce preeclampsia-like symptoms. Total and CD206-positive macrophages were quantified in placentas of these animals.
  
  
  RESULTS
  Lower percentages of classical monocytes were found in pregnant women (91%-[83-98%]) compared to nonpregnant women (94%-[90-98%]) and even less in preeclamptic patients (90%-[61-92%]). In contrast, the percentage of combined nonclassical/intermediate monocytes was higher in pregnant women (8.5%-[2.3-16.6%] vs. 5.6%-[1.9-9.5%]) and even higher in preeclamptic patients (9.9%-[7.8-38.7%]), which was caused by a selective increase of intermediate monocytes. In rats, we also found lower percentages of classical monocytes and higher percentages of nonclassical monocytes in pregnant versus nonpregnant rats. ATP infusion increased the percentage of nonclassical monocytes in pregnant rats even further but not in nonpregnant rats. These nonclassical monocytes showed a more activated phenotype in pregnant ATP-infused rats only. Mesometrial triangles of ATP-infused rats had less CD206-positive macrophages as compared to those of saline-infused rats.
  
  
  CONCLUSIONS
  The higher percentage of nonclassical/intermediate monocytes found in pregnancy and preeclampsia confirms their association with inflammatory responses. The observation that ATP stimulated numbers/activation of nonclassical monocytes in pregnant rats only, suggests that nonclassical monocytes are specifically altered in pregnancy and may play a role in the pathophysiology of preeclampsia.
authors.affiliation: Division of Medical Biology, Department of Pathology and Medical Biology, University Medical Center Groningen and University of Groningen, Groningen, The Netherlands.
authors.forename: Barbro N
authors.initials: BN
authors.lastname: Melgert
authors.forename: Floor
authors.initials: F
authors.lastname: Spaans
authors.forename: Theo
authors.initials: T
authors.lastname: Borghuis
authors.forename: Pieter A
authors.initials: PA
authors.lastname: Klok
authors.forename: Bart
authors.initials: B
authors.lastname: Groen
authors.forename: Annemarie
authors.initials: A
authors.lastname: Bolt
authors.forename: Paul
authors.initials: P
authors.lastname: de Vos
authors.forename: Maria G
authors.initials: MG
authors.lastname: van Pampus
authors.forename: Tsz Y
authors.initials: TY
authors.lastname: Wong
authors.forename: Harry
authors.initials: H
authors.lastname: van Goor
authors.forename: Winston W
authors.initials: WW
authors.lastname: Bakker
authors.forename: Marijke M
authors.initials: MM
authors.lastname: Faas
mesh_terms: D000255:Adenosine Triphosphate; D000328:Adult; D000818:Animals; D015703:Antigens, CD / Q000276:immunology; D005260:Female; D005434:Flow Cytometry; D006801:Humans; D007958:Leukocyte Count; D009000:Monocytes / Q000145:classification* / Q000276:immunology / Q000473:pathology*; D010920:Placenta / Q000276:immunology / Q000473:pathology*; D011225:Pre-Eclampsia / Q000139:chemically induced / Q000276:immunology / Q000473:pathology*; D011247:Pregnancy; D051381:Rats
chemical_list: D015703:Antigens, CD; D000255:Adenosine Triphosphate