title: Nitric oxide synthase-2 and expression of perforin in uterine NK cells.
abstract: In human, mouse, and rat pregnancy, maternal NK cells accumulate and differentiate at implantation sites. These cells, termed uterine NK (uNK) cells, express NO synthase (NOS)-2 and develop cytolytic molecules such as perforin and granzymes during differentiation in situ. In this study, relationships between expression of the NOS-2 gene, uNK cell population density and tissue distribution, and synthesis of perforin were investigated. Uteri from wild-type (WT) and NOS-2-/- mice were collected at gestation days (g.d.) 8, 10, 12, 14, and 16 (n, >2/g.d.). Histochemical staining failed to reveal any differences between the population densities or tissue distributions of uNK cells in WT and NOS-2-/- uteri at any stage of gestation. By contrast, immunohistochemical staining with anti-perforin Abs demonstrated significantly fewer perforin-positive uNK cells in two uterine compartments of NOS-2-/- mice in comparison to the same compartments in WT mouse uteri. Perforin-positive uNK cells were reduced in NOS-2-/- metrial glands at g.d. 8, 10, and 12 and in decidua basalis at g.d. 12 (p < 0.05). Analysis of perforin protein by immunoblotting confirmed this observation. Northern blot hybridization studies showed that loss of perforin protein in NOS-2-/- mice was accompanied by decreased steady-state levels of perforin mRNA. These results demonstrate that migration of uNK cells into the uterus, selection of residency sites, and proliferation in situ are independent of NOS-2. By contrast, their differentiation, including transcription and translation of the cytotoxic molecule perforin, was shown to rely on normal expression of the NOS-2 gene.
authors.affiliation: Department of Anatomy, University of Kansas Medical Center, Kansas City, KS 66160, USA.
authors.forename: T G
authors.initials: TG
authors.lastname: Burnett
authors.forename: J S
authors.initials: JS
authors.lastname: Hunt
mesh_terms: D000818:Animals; D015536:Down-Regulation / Q000235:genetics / Q000276:immunology; D010064:Embryo Implantation / Q000235:genetics; D005260:Female; D007694:Killer Cells, Natural / Q000201:enzymology* / Q000378:metabolism; D018655:Lymphocyte Count; D008562:Membrane Glycoproteins / Q000096:biosynthesis* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019001:Nitric Oxide Synthase / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D052247:Nitric Oxide Synthase Type II; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D011247:Pregnancy; D012333:RNA, Messenger / Q000096:biosynthesis; D014599:Uterus / Q000166:cytology / Q000201:enzymology* / Q000276:immunology* / Q000378:metabolism
chemical_list: D008562:Membrane Glycoproteins; D052899:Pore Forming Cytotoxic Proteins; D012333:RNA, Messenger; D054353:Perforin; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse