Receptors for non-MHC ligands contribute to uterine natural killer cell activation during pregnancy in mice

Placenta. 2013 Sep;34(9):757-64. doi: 10.1016/j.placenta.2013.06.004. Epub 2013 Jun 24.

Abstract

Introduction: Activated uterine natural killer (uNK) cells are abundant in early human and mouse decidual basalis. In mice, distinct uNK cell subsets support early endothelial tip cell induction, the pruning of new vessels and initiation of spiral arterial modification. While genetic studies indicate that NK/uNK cell activation via receptors recognizing Class I MHC-derived peptides promotes human pregnancy, roles for other activation receptors expressed by NK cells, such as the aryl hydrocarbon receptor (AHR) and natural cytotoxicity receptors (NCR) are undefined in human or mouse pregnancies.

Methods: Expression of AHR and NCR1 (ortholog of human NKp46) by gestation day (gd)10.5 mouse uNK cell subsets was measured by quantitative real-time RT-PCR. Early implantation sites from mice lacking expression of either receptor were examined histologically.

Results: Gd10.5 uNK cell subsets, separated by reactivity to Dolichos biflorus agglutinin lectin, differed in relative transcript abundance for Ahr and Ncr1. Quantitative histology revealed that, in comparison to C57BL/6 controls, implant sites from gd10.5 Ahr(-/-) and gd6.5-12.5 UkCa:B6.Ncr1(Gfp/Gfp) mice had normal uNK cell abundance but the uNK cells were smaller than normal and unable to trigger spiral arterial remodeling. Whole mount immunohistochemistry comparisons of viable, gd6.5-8.5 Ncr1(Gfp/Gfp) and C57BL/6 implant sites revealed deficits in implant site angiogenesis and conceptus growth in Ncr1(Gfp/Gfp).

Discussion: In mice, activation of AHR and of NCR1 by endogenous, as yet undefined ligands, contributes to uNK cell activation/maturation and angiogenic functions during early to mid-gestation pregnancy. MHC-independent activation of uNK cells also likely makes critical contributions to human pregnancy success.

Keywords: Arylhydrocarbon receptor; Decidua; Histology; Natural cytotoxicity receptor; Reproductive immunology; Spiral artery remodeling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Agglutinins / pharmacology
  • Animals
  • Antigens, Ly / genetics
  • Antigens, Ly / metabolism
  • Basic Helix-Loop-Helix Transcription Factors / agonists*
  • Basic Helix-Loop-Helix Transcription Factors / genetics
  • Basic Helix-Loop-Helix Transcription Factors / metabolism
  • Decidua / cytology
  • Decidua / immunology*
  • Decidua / metabolism
  • Embryo Implantation / drug effects
  • Female
  • Gene Expression Regulation, Developmental* / drug effects
  • Killer Cells, Natural / cytology
  • Killer Cells, Natural / drug effects
  • Killer Cells, Natural / immunology*
  • Killer Cells, Natural / metabolism
  • Leukopoiesis / drug effects
  • Ligands
  • Lymphocyte Activation* / drug effects
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Mice, Transgenic
  • Natural Cytotoxicity Triggering Receptor 1 / agonists*
  • Natural Cytotoxicity Triggering Receptor 1 / genetics
  • Natural Cytotoxicity Triggering Receptor 1 / metabolism
  • Placentation / drug effects
  • Plant Lectins / pharmacology
  • Pregnancy
  • Receptors, Aryl Hydrocarbon / agonists*
  • Receptors, Aryl Hydrocarbon / genetics
  • Receptors, Aryl Hydrocarbon / metabolism
  • Uterus / cytology
  • Uterus / drug effects
  • Uterus / immunology*
  • Uterus / metabolism

Substances

  • Agglutinins
  • Ahr protein, mouse
  • Antigens, Ly
  • Basic Helix-Loop-Helix Transcription Factors
  • Ligands
  • Natural Cytotoxicity Triggering Receptor 1
  • Ncr1 protein, mouse
  • Plant Lectins
  • Receptors, Aryl Hydrocarbon
  • dolichos biflorus agglutinin

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