Differential Gene Expression in Endometrium, Endometrial Lymphocytes, and Trophoblasts during Successful and Abortive Embryo Implantation

Abstract

Prenatal mortality reaching 30% occurs during the first weeks of gestation in commercial swine. Mechanisms for this are unknown although poor uterine blood supply has been postulated. In other species, vascular endothelial growth factor, hypoxia-inducible factor 1-α, and IFN-γ regulate gestational endometrial angiogenesis. Vascular endothelial growth factor and hypoxia-inducible factor 1-α are also important for placental angiogenesis while trophoblastic expression of Fas ligand is thought to protect conceptuses against immune-mediated pregnancy loss. In this study, we document dynamic, peri-implantation differences in transcription of genes for angiogenesis, cytokine production, and apoptosis regulation in the endometrium, and laser capture microdissected endometrial lymphocytes and trophoblasts associated with healthy or viable but arresting porcine fetuses. In healthy implantation sites, endometrial gene expression levels differed between anatomic subregions and endometrial lymphocytes showed much greater transcription of angiogenic genes than trophoblasts. In arresting fetal sites, uterine lymphocytes had no angiogenic gene transcription and showed rapid elevation in transcription of proinflammatory cytokines Fas and Fas ligand while trophoblasts showed elevated transcription of IFN-γ and Fas. This model of experimentally accessible spontaneous fetal loss, involving blocked maternal angiogenesis, should prove valuable for further investigations of peri-implantation failure of normally conceived and surgically transferred embryos in many species, including the human.

A Review of Gene Expression in Porcine Endometrial Lymphocytes, Endothelium and Trophoblast During Pregnancy Success and Failure

“…In comparison with lymphocytes from nonpregnant uteri, transcripts for VEGF (Fig. 3) and PlGF (data not shown) were progressively elevated in lymphocytes from healthy attachment sites between GD15-50 [15,16,38]. These findings were supported by immunohistochemistry, which demonstrated translation of these genes by lymphocytes as well as by other cell types.…”

“…Beta actin was selected as the most stable of three housekeeping genes examined across the interval of study and was used for calculation of relative gene expression. Our comparisons of the levels of transcription of angiogenic factors in endometrium, in endometrial cell types and in trophoblasts from healthy and arresting porcine littermate attachment sites has linked loss of tissue oxygen sensing and angiogenic molecules from endometrial lymphocytes with fetal growth arrest [15,16]. These studies, their background and extension are summarized below.…”

The vascular endothelial growth factor (VEGF) +405 G/C polymorphism and its relationship with recurrent implantation failure in women in an IVF programme with ICSI

“…It also plays a critical role in oocyte maturation, decidualized endometrial vascularization, embryo implantation/development and placenta angiogenesis/vascularization in early gestation [16,24,25,47]. Inadequate angiogenesis is known to be associated with RIF in both animal [40] and human studies [21]. In the present study, women with RIF had a higher frequency of the VEGF +405 C/C genotype (resulting in lower VEGF expression) than control patients did.…”

Differentiation of Uterine Natural Killer Cells in Pregnant SCID (scid/scid) Mice

“…The uNK cells are observed in the metrial gland (MG) and decidua basalis (DB) of each implantation site, proliferate in the MG by day 12 of pregnancy, differentiate in the DB by day15 and degenerate during late pregnancy [1,9]. The uNK cells can produce several cytokines and growth factors, having crucial roles in pregnancy maintenance, particularly decidual health and modification of spiral arteries [12,16]. Peripheral NK cells and splenic NK cells are known to be affected in their differentiation and/or proliferation by cytokines and growth factors derived from functional T-and B-cells [14].…”

“…Subtype I and II cells are immature and not functional, and those immature cells differentiate into mature subtype III cells that can play an essential role in modification and reconstruction of spiral arteries; ultimately, functional subtype III cells change to Subtype IV cells undergoing apoptosis [9,12,16]. Although the number of subtype II cells was significantly lower in the SCID mice on day 8 of pregnancy, differentiation and/or proliferation of uNK cells in the SCID mice returned to the control level by day 12 of pregnancy.…”