title: Uterine natural killer cells: insights into their cellular and molecular biology from mouse modelling.
abstract: In primates, including women, and in rodents, natural killer lymphocytes (NK cells) have a unique relationship with the decidualizing uterus. Implantation sites from genetically modified and transplanted mice have proven useful models for understanding potential mechanisms involved in the recruitment, activation and functions of human CD56(bright) uterine (u)NK cells. Key findings are reviewed in this article. In mice, uNK precursor cells are recruited from secondary lymphoid tissues and are activated coincident with their uterine arrival. uNK cells proliferate, produce cytokines (interferon gamma (IFN-gamma) and interleukin 18 (IL-18) and IL-27), and terminally differentiate into granulated lymphocytes. Many uNK cells proliferate within the myometrium at each implantation site forming a structure, the mesometrial lymphoid aggregate of pregnancy (MLAp) that surrounds blood vessels servicing each placenta. Post-mitotic uNK cells are abundant within decidua basalis; frequently (<25%) associating with spiral arteries, intramurally and intraluminally. From mid-gestation, numbers of uNK cells decline. Studies of implantation sites in mice lacking uNK cells, IFN-gamma, components of IFN-gamma-induction and -signalling pathways or IFN-gamma-regulated genes indicate that uNK cell-derived IFN-gamma is essential in triggering pregnancy-induced spiral artery modification. Decidual maintenance and uNK cell death are additional effects of uNK cell-derived IFN-gamma. Thus, during the first half of gestation, uNK cells contribute to and sustain important changes in the maternal placental bed.
authors.affiliation: Department of Biomedical Sciences, Ontario Veterinary College, University of Guelph, Guelph, ON, N1G 2W1, Canada. acroy@uoguelph.ca
authors.forename: B Anne
authors.initials: BA
authors.lastname: Croy
authors.forename: Hong
authors.initials: H
authors.lastname: He
authors.forename: Souad
authors.initials: S
authors.lastname: Esadeg
authors.forename: Qingxia
authors.initials: Q
authors.lastname: Wei
authors.forename: Daniel
authors.initials: D
authors.lastname: McCartney
authors.forename: Jianhong
authors.initials: J
authors.lastname: Zhang
authors.forename: Angela
authors.initials: A
authors.lastname: Borzychowski
authors.forename: Ali A
authors.initials: AA
authors.lastname: Ashkar
authors.forename: Gordan P
authors.initials: GP
authors.lastname: Black
authors.forename: Sharon S
authors.initials: SS
authors.lastname: Evans
authors.forename: Sirirak
authors.initials: S
authors.lastname: Chantakru
authors.forename: Marianne
authors.initials: M
authors.lastname: van den Heuvel
authors.forename: Valdemar A
authors.initials: VA
authors.lastname: Paffaro
authors.forename: Aureo T
authors.initials: AT
authors.lastname: Yamada
mesh_terms: D000818:Animals; D003656:Decidua / Q000276:immunology*; D005260:Female; D005865:Gestational Age; D006801:Humans; D007371:Interferon-gamma / Q000235:genetics / Q000276:immunology; D019409:Interleukin-15 / Q000276:immunology; D007694:Killer Cells, Natural / Q000166:cytology / Q000502:physiology*; D008213:Lymphocyte Activation; D051379:Mice; D008822:Mice, Transgenic; D023421:Models, Animal; D011247:Pregnancy; D014599:Uterus / Q000276:immunology*
chemical_list: D019409:Interleukin-15; D007371:Interferon-gamma