Department of Veterinary Integrative Biosciences, School of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, USA.
Department of Animal and Avian Sciences, College of Agriculture & Natural Resources, University of Maryland, College Park, MD, USA.
Biol Reprod. 2024 Jul 12;111(1):174-185. doi: 10.1093/biolre/ioae044.
Interferon-gamma (IFNG) is a pro-inflammatory cytokine secreted by the porcine conceptus (embryo and extra-embryonic membranes) during the peri-implantation period of pregnancy. IFNG modifies the endometrial inflammatory immune response and is required for the implantation and survival of the conceptus. It is not known how IFNG from the conceptus trophectoderm is transported across the endometrial luminal epithelium (LE). In the present study, immunofluorescence analyses detected immunoreactive IFNG protein in both the trophectoderm and endometrial LE on Day 15 of pregnancy, while our previous research localized IFNG mRNA only to conceptus trophectoderm. Using minced endometrial explants to disrupt the barrier posed by the intact endometrial LE, treatment with recombinant IFNG induced the expression of genes that were not induced when IFNG was infused into the uterine lumen in vivo by McLendon et al. (Biology of Reproduction. 2020;103(5):1018-1029). We hypothesized that during pregnancy extracellular vesicles (EVs) serve as intercellular signaling vehicles to transport conceptus-derived IFNG across the intact endometrial LE and into the stromal compartment of the uterus. Western blotting detected the presence of IFNG in EVs isolated from the uterine fluid of pregnant gilts, but not nonpregnant gilts. Real-time PCR demonstrated increased expression of IFNG-stimulated genes in EV-treated endometrial explants and EV-mediated IFNG transport was confirmed in whole uterine sections cultured with EVs from Day 15 of pregnancy. These results suggest that EVs are involved in IFNG transport across the endometrial LE to enable paracrine communication between the conceptus and cells within the endometrial stroma.
干扰素-γ（IFNG）是一种促炎细胞因子，由猪胚泡（胚胎和胚胎外膜）在妊娠植入期分泌。IFNG 改变子宫内膜炎症免疫反应，是胚胎植入和存活所必需的。目前尚不清楚胚泡滋养外胚层中的 IFNG 如何穿过子宫内膜腔上皮（LE）。在本研究中，免疫荧光分析在妊娠第 15 天检测到滋养外胚层和子宫内膜 LE 中均有免疫反应性 IFNG 蛋白，而我们之前的研究仅将 IFNG mRNA 定位到胚泡滋养外胚层。使用切碎的子宫内膜外植体破坏完整子宫内膜 LE 构成的屏障，用重组 IFNG 处理会诱导那些在 McLendon 等人通过体内向子宫腔输注 IFNG 时不会诱导的基因表达（生殖生物学。2020；103(5):1018-1029）。我们假设在怀孕期间，细胞外囊泡（EVs）作为细胞间信号传递载体，将胚泡衍生的 IFNG 穿过完整的子宫内膜 LE 并运送到子宫的基质区室。Western blot 检测到从妊娠母猪子宫液中分离的 EVs 中存在 IFNG，但从非妊娠母猪中未检测到。实时 PCR 表明，在 EV 处理的子宫内膜外植体中 IFNG 刺激基因的表达增加，并且在培养有来自妊娠第 15 天的 EV 的整个子宫切片中证实了 EV 介导的 IFNG 转运。这些结果表明，EVs 参与 IFNG 穿过子宫内膜 LE 的转运，以实现胚泡与子宫内膜基质细胞之间的旁分泌通讯。
