title: MIC-1 (a multifunctional modulator of dendritic cell phenotype and function) is produced by decidual stromal cells and trophoblasts.
abstract: BACKGROUND
  Macrophage inhibitory cytokine-1 (MIC-1) is a multifunctional cytokine produced in high amounts by placental tissue. Inhibiting trophoblast invasion and suppressing inflammation through inhibition of macrophage activation, MIC-1 is thought to provide pleiotropic functions in the establishment and maintenance of pregnancy. So far, little is known about the decidual cell subsets producing MIC-1 and the effect of this cytokine on dendritic cells (DCs), which are known to play a distinct role in the development of pro-fetal tolerance in pregnancy.
  
  
  METHODS
  To identify the decidual cell types expressing and secreting MIC-1, immunohistochemical staining, PCR experiments, western blot analysis and ELISAs were performed. Immature DCs (iDCs) were generated from peripheral blood-derived monocytes and differentiated in the presence of MIC-1 or dexamethasone (Dex) for control. Migratory and proliferative activity of DCs after MIC-1 exposure was investigated by migration and proliferation assay. Cytokine secretion after MIC-1 exposure was tested in isolated uNK cells, isolated CD14+ monocytes, monocyte-derived iDCs and mature DCs. Subsequently, the phenotype of DCs was studied using FACS analysis. To test the T-cell stimulatory capacity of pre-incubated DCs, mixed lymphocyte reaction was applied. Finally, the expression of the tryptophan-catabolizing enzyme indoleamine 2,3-dioxygenase (IDO) after the exposure of MIC-1 to maturing DCs was analysed by western blot.
  
  
  RESULTS
  Immunohistochemical staining, PCR and western blot experiments demonstrated that MIC-1 is mainly expressed by trophoblast cells and decidual stromal cells. Analysis of the MIC-1 secretion of decidual cell types by ELISA again characterized trophoblast and stromal cells as main producers. The migratory activity of iDCs was significantly induced by MIC-1. No changes in proliferative activity of DCs were observed after MIC-1 pre-incubation. The secretion of pro- or anti-inflammatory cytokines was not affected significantly by MIC-1. Studying the phenotype of DCs after MIC-1 exposure by FACS analysis, we observed that MIC-1 suppresses the expression of typical maturation molecules such as CD25 and CD83 as well as of CD86 during cytokine-induced DC maturation similar to Dex. In addition, T-cell stimulatory capacity of DCs was significantly reduced after MIC-1 exposure. MIC-1 was also able to increase slightly the expression of IDO (a key immunomodulatory enzyme promoting periphereal tolerance) in maturing DCs.
  
  
  CONCLUSIONS
  We have identified MIC-1 as a novel factor (secreted by decidual cells in early pregnancy) that could promote the increase of a tolerogenic subtype of DC in decidua.
authors: Department of Obstetrics and Gynaecology, University of Wuerzburg, Josef-Schneider-Straße 4, Wuerzburg D-97080, Germany. segerer_s1@klinik.uni-wuerzburg.de
authors: S E
authors: SE
authors: Segerer
authors: L
authors: L
authors: Rieger
authors: M
authors: M
authors: Kapp
authors: Y
authors: Y
authors: Dombrowski
authors: N
authors: N
authors: Müller
authors: J
authors: J
authors: Dietl
authors: U
authors: U
authors: Kämmerer
mesh_terms: D015703:Antigens, CD / Q000096:biosynthesis; D051940:B7-2 Antigen / Q000096:biosynthesis; D002465:Cell Movement; D049109:Cell Proliferation; D003656:Decidua / Q000166:cytology*; D005260:Female; D005434:Flow Cytometry; D055436:Growth Differentiation Factor 15 / Q000096:biosynthesis*; D006801:Humans; D007136:Immunoglobulins / Q000096:biosynthesis; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase / Q000378:metabolism*; D007249:Inflammation; D053645:Interleukin-2 Receptor alpha Subunit / Q000096:biosynthesis; D008562:Membrane Glycoproteins / Q000096:biosynthesis; D009000:Monocytes / Q000166:cytology; D010641:Phenotype; D017154:Stromal Cells / Q000166:cytology*; D016212:Transforming Growth Factor beta / Q000378:metabolism; D014327:Trophoblasts / Q000166:cytology*; D000097802:CD83 Antigen
chemical_list: D015703:Antigens, CD; D051940:B7-2 Antigen; D055436:Growth Differentiation Factor 15; D007136:Immunoglobulins; D050503:Indoleamine-Pyrrole 2,3,-Dioxygenase; D053645:Interleukin-2 Receptor alpha Subunit; D008562:Membrane Glycoproteins; D016212:Transforming Growth Factor beta; D000097802:CD83 Antigen; C526140:GDF15 protein, human