Rapid conceptus elongation in the pig: An interleukin 1 beta 2 and estrogen‐regulated phenomenon

Abstract

Establishment and maintenance of pregnancy in the pig involves activating many physiological, cellular, and molecular signaling pathways between the developing conceptus and hormonally regulated maternal endometrium. Rapid elongation of the pig trophoblast allows for the establishment of sufficient placental surface area for the transport of nutrients to the fetus throughout pregnancy. Estrogens secreted by the conceptus during elongation act on uterine epithelia to induce secretion of uterine factors required for conceptus development and for preventing endocrine secretion of prostaglandin F2α, which would cause luteolysis. Thus, trophoblast expansion within the uterine lumen during early gestation is an essential process for implantation and maintenance of pregnancy in species with an epitheliochorial form of placentation. In the pig, rapid conceptus elongation involves the unique expression of interleukin-1 beta 2 (IL1B2), which establishes pro-inflammatory effects that may be tempered by the spatiotemporal secretion of estrogen from the conceptuses. The present review provides current information on pig conceptus remodeling and signaling via estrogen and IL1B2 pathways, as well as endometrial responses to those conceptus factors leading to establishment of pregnancy.embryo, endometrium, placenta, pregnancy[The] unique capacity of pig conceptuses to rapidly remodel and elongate, compared with other mammals, is an essential mechanism developed to establish pregnancy.

Pig Pregnancies after Transfer of Allogeneic Embryos Show a Dysregulated Endometrial/Placental Cytokine Balance: A Novel Clue for Embryo Death?

“…Additionally, at D18 of pregnancy, we found a clear increase of the pro-inflammatory interleukin IL-1β in the C+ group compared to non-pregnant sows. This pro-inflammatory interleukin and its signaling system are expressed in the porcine endometrium and conceptuses during the peri-implantation period [39][40][41] inducing increases of the MAPK and NFKB activities in the endometrium [42], which stimulates the expression of genes involved in immune modulation, cell adhesion, and angiogenesis [17,43]. Immediately following implantation, IL-1β expression rapidly declines and the uterine content of IL-1β slowly decreases over the next few days and returns to pre-elongation concentrations [39], which is in accordance with our results at D24 of pregnancy where endometrial IL-1β concentrations tended to decrease in AI-pregnant sows compared to the non-pregnant controls.…”

Integrated Analysis of miRNA-mRNA Network Reveals Different Regulatory Patterns in the Endometrium of Meishan and Duroc Sows during Mid-Late Gestation

“…Estradiol regulates expression of IHH in the mammalian uterus and plays a role in development of the placenta [68,69]. The effects of estradiol in the uterus are mediated by ESR1, which is the predominant type of estrogen receptor in the mature uterus [70,71]. Based on the results of the dual luciferase assay, ssc-miR-671-5p appears to downregulate the expression of ESR1 ( Figure 9B).…”

“…In our study, enriched GO terms that were in common between DU72 vs. MS72 and MS49 vs. MS72 in the miRNA-mRNA interaction networks included genes and miRNAs involved in responding to estradiol ( Figures 6 and 7 and Table 3). Down regulated genes in MS72 such as IHH and ESR1 are known to affect placental development in mammals [68][69][70]. Estradiol regulates expression of IHH in the mammalian uterus and plays a role in development of the placenta [68,69].…”

Changes in calcium levels in the endometrium throughout pregnancy and the role of calcium on endometrial gene expression at the time of conceptus implantation in pigs

“…Between Days 10 and 12 of pregnancy, the porcine conceptus undergoes a dramatic morphological transition from spherical (10−15 mm in length) to tubular (15−50 mm) and then filamentous (100−800 mm) forms (Bazer & Johnson, ). Trophectoderm cells of the elongating conceptus synthesize and secrete a large amount of estrogen and interleukin‐1 beta 2 (IL1B2) on Day 12 and interferon (IFN)‐γ and IFN‐δ on Days 13–18 (Bazer & Johnson, ; Geisert et al, ).…”

“…(100−800 mm) forms . Trophectoderm cells of the elongating conceptus synthesize and secrete a large amount of estrogen and interleukin-1 beta 2 (IL1B2) on Day 12 and interferon (IFN)-γ and IFN-δ on Days 13-18 Geisert et al, 2017).…”