1. IFN treatment of human midgestation villous explants induces syncytial knot formation.
IFN treatment of human midgestation villous explants induces syncytial knot formation. (A) Human midgestation (19 to 23 weeks) chorionic villi were isolated, placed in culture, and treated with 100 or 1000 U of recombinant human IFN-β or 1000 U of IFN-λ3 for ~16 to 20 hours. Villous explants were harvested, fixed in PFA, and stained for CK19 (green, trophoblasts) and actin (red). DAPI-stained nuclei are shown in blue and differential interference contrast (DIC) (bottom). Scale bars, 100 μm. Images are representative of villi isolated from four donors. Arrow indicates syncytial knot. (B) Three-dimensional image reconstruction of mock- or IFN-β (1000 U)–treated explants stained for CK19 (green) and actin (red). DAPI-stained nuclei are shown in blue. Scale bars, 20 μm. (C) Quantification of syncytial knot size using Imaris in villi treated with 10, 100, or 1000 U of IFN-β or 1000 U of IFN-λ3 for ~24 hours. Each symbol represents an individual villous from a total of three donors, and the black line represents the mean. ***P < by Dunnett’s multiple comparison test to mock. ns, not significant. (D) Confocal micrographs of mock- or IFN-β (1000 U)–treated villi stained for actin (red, right). DIC is shown on the left. White box denotes zoomed area shown at the bottom left (mock) or right (IFN-β). Scale bars, 20 μm.
Laura J. Yockey et al. Sci. Immunol. 2018;3:eaao1680
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