Vascular Endothelial Growth Factor A and VEGFR-1 Change during Preimplantation in Heifers

Metabolomic evolution of the postpartum dairy cow uterus

High rates of early pregnancy loss are a critical issue in dairy herds, particularly in seasonal, grazing systems. Components of the uterine luminal fluid (ULF), on which the early embryo depends for sustenance and growth, partly determine early pregnancy losses. Here, changes in ULF from early to mid-postpartum in crossbred dairy cows were explored, linking them with divergent embryo development. For this, the uteri of 87 cows at Day 7 of pregnancy at first and third estrus postpartum were flushed to collect ULF. Eighteen metabolites (chiefly organic acids and sugars) significantly varied in abundance across postpartum, indicating a molecular signature of physiological recovery consistent of the upregulation of pyrimidine metabolism and glycerophospholipid metabolism, and downregulation of pentose phosphate and taurine metabolism pathways. Joint pathway analysis of metabolomics data and a previously generated proteomics data set on the same ULF samples suggests key links between postpartum recovery and subsequent successful embryo development. These include upregulation of VEGFA and downregulation of metabolism, NRF2, T-cell receptor, which appear to improve the ULF's capacity of sustaining normal embryo development, and a putative osmo-protectant role of beta-alanine. These relationships should be further investigated to develop tools to detect and reduce early pregnancy loss in dairy cows.

Expression profile of genes related to pregnancy maintenance in Dromedary Camel during the first trimester

So far, few signals involved in embryo-maternal dialogue have been identified in pregnant she-camel. Our objective was to investigate expression profiles of genes relevant to uterine extracellular matrix remodeling (ITGB4, SLCO2A1, FOS, and JUN), uterine tissue vascularization, and placental formation (VEGFA, PGF, and PDGFA), embryonic growth and development (IGF1 and PTEN), plus cell death of uterine tissue (BCL2) in early pregnant versus non-pregnant she-camels. Forty genital tracts (20 pregnant and 20 non-pregnant) and blood samples were collected from abattoirs. Total RNA was extracted from uterine tissues and qRT-PCR was conducted for candidate genes. Serum concentrations of progesterone (P4) and estradiol17-β (E2) were measured. Expression of ITGB4, FOS, and PGF genes increased (P < 0.001) in the right uterine horn of pregnant versus non-pregnant she-camels. Moreover, JUN, SLCO2A1, VEGFA, and PTEN mRNAs were up-regulated (P < 0.001) in various segments of uterine tissues in pregnant groups. The PDGFA transcript was over-expressed (P < 0.001) in both uterine horns of pregnant groups. Additionally, IGF1 was higher (P < 0.001) in the right horn and the uterine body of pregnant groups, and expression of BCL2 was increased (P < 0.001) in the pregnant uterine body. Moreover, serum concentrations of P4 were higher (P < 0.001) and E2 lower (P < 0.05) in pregnant she-camels. Taken together, the fine-tuning of genes related to implantation, matrix formation, vascularization, and placental formation is highly required for successful pregnancy in she-camels.

Expression of NFIL3 and CEBPA regulated by IFNT induced-PGE2 in bovine endometrial stromal cells during the pre-implantation period

Prostaglandin E2 (PGE2) is considered as a luteoprotective factor, influencing the corpus luteum during the early pregnant period in the bovine species. Cyclic AMP (cAMP) is activated in response to PGE2 and plays a role in many physiological processes. The maternal recognition signal, interferon τ (IFNT), induces PGE2 secretion from the endometrial epithelial cells, the function of which in stroma cells has not been completely understood. In this study, PGE2 was found to activate cAMP in the bovine endometrial stromal cells (STRs). STRs were then treated with forskolin to activate the cAMP signaling, from which RNA extracted was subjected to global expression analysis. Transcripts related to transcription regulatory region nucleic acid binding of molecular function, nucleus of cellular component, and mitotic spindle organization of biological processes were up-regulated in cAMP-activated bovine STRs. An increase in the transcription factors, NFIL3, CEBPA, and HIF1A via the cAMP/PKA/CREB signaling pathway in the bovine STRs was also found by qPCR. Knockdown of NFIL3, CEBPA, or HIF1A blocked forskolin-induced PTGS1/2 and IGFBP1/3 expression. Moreover, NFIL3 and CEBPA were localized in endometrial stroma on pregnant day 17 (day 0 = estrous cycle), but not on cyclic day 17. These observations indicated that uterine PGE2 induced by conceptus IFNT is involved in the early pregnancy-related gene expression in endometrial stromal cells, which could facilitate pregnancy establishment in the bovine.

The Focus on Core Genetic Factors That Regulate Hepatic Injury in Cattle Seems to be Important for the Dairy Sector’s Long-Term Development

The cattle during the perinatal period, as well as malnutrition, generate oxidative stress which leads to high culling rates of calves after calving across the world. Although metabolic diseases have such a negative impact on the welfare and economic value of dairy cattle, that becomes a serious industrial concern across the world. According to research, genetic factors have a role or controlling fat deposition in the liver by influencing the biological processes of hepatic lipid metabolism, insulin resistance, gluconeogenesis, oxidative stress, endoplasmic reticulum stress, and inflammation, all of which contribute to hepatic damage. This review focuses on the critical regulatory mechanisms of VEGF, mTOR/AKT/p53, TNF-alpha, Nf-kb, interleukin, and antioxidants that regulate lipid peroxidation in the liver via direct or indirect pathways, suggesting that they could be a potential critical therapeutic target for hepatic disease.

Luminal and Glandular Epithelial Cells from the Porcine Endometrium maintain Cell Type-Specific Marker Gene Expression in Air-Liquid Interface Culture

Two different types of epithelial cells constitute the inner surface of the endometrium. While luminal epithelial cells line the uterine cavity and build the embryo-maternal contact zone, glandular epithelial cells form tubular glands reaching deeply into the endometrial stroma. To facilitate investigations considering the functional and molecular differences between the two populations of epithelial cells and their contribution to reproductive processes, we aimed at establishing differentiated in vitro models of both the luminal and the glandular epithelium of the porcine endometrium using an air–liquid interface (ALI) approach. We first tested if porcine luminal endometrium epithelial cells (PEEC-L) reproducibly form differentiated epithelial monolayers under ALI conditions by monitoring the morphology and the trans-epithelial electrical resistance (TEER). Subsequently, luminal (PEEC-L) and glandular epithelial cells (PEEC-G) were consecutively isolated from the endometrium of the uterine horn. Both cell types were characterized by marker gene expression analysis immediately after isolation. Cells were separately grown at the ALI and assessed by means of histomorphometry, TEER, and marker gene expression after 3 weeks of culture. PEEC-L and PEEC-G formed polarized monolayers of differentiated epithelial cells with a moderate TEER and in vivo-like morphology at the ALI. They exhibited distinct patterns of functional and cell type-specific marker gene expression after isolation and largely maintained these patterns during the culture period. The here presented cell culture procedure for PEEC-L and -G offers new opportunities to study the impact of embryonic signals, endocrine effectors, and reproductive toxins on both porcine endometrial epithelial cell types under standardized in vitro conditions.

Retinal microvasculature and time to pregnancy in a multi-ethnic pre-conception cohort in Singapore

STUDY QUESTION

Can abnormalities in retinal microvasculature representing adverse microcirculatory perfusion and inflammation shed light on the pathophysiology of female fecundability?

SUMMARY ANSWER

In our prospective study, abnormalities in retinal vascular geometric morphology (i.e. sparser arteriolar fractal and larger venular bifurcation) during pre-conception phase are temporarily associated with a prolonged time-to-pregnancy (TTP).

WHAT IS KNOWN ALREADY

Suboptimal retinal microcirculatory morphology has been associated with obesity, psychological stress and hypertension, all of which are known risk factors for reduced female fecundability.

STUDY DESIGN, SIZE, DURATION

A total of 652 women of Chinese, Malay or Indian ethnicity 18-45 years of age and planning to conceive spontaneously within the next 12 months were recruited during the pre-conception period into the Singapore PREconception Study of long-Term maternal and child Outcomes (S-PRESTO), from February 2015 to October 2017.

PARTICIPANTS/MATERIALS, SETTING, METHODS

During recruitment, we collected information on socio-demographic factors, menstrual characteristics and lifestyle behaviors and made anthropometric measurements. We assessed the following retinal microvascular features: caliber, branching angle and fractal dimension. We conducted follow-up telephone surveys to track each participant's pregnancy status at 6, 9 and 12 months after enrolment. We ascertained clinical pregnancies via ultrasonography, with TTP measured by the number of menstrual cycles required to achieve a clinical pregnancy over a 1-year follow-up. Then, we performed discrete-time proportional hazards models to estimate the fecundability odds ratio (FOR) and 95% CI for each retinal microvascular feature in association with TTP, after adjusting for major confounders, including body mass index and fasting glycemic level at study entry.

MAIN RESULTS AND THE ROLE OF THE CHANCE

Among 652 recruited women, 276 (42.3%) successfully conceived within 1 year of follow-up. The mean (and SD) was 1.24 (0.05) Df for retinal arteriolar dimension fraction and 78.45 (9.79) degrees for retinal venular branching angle, respectively. Non-linear relationship testing was performed before multiple adjustment in all associations and a non-monotonic association was detected between retinal venular branching angle and TTP. Compared with women in the highest tertile of retinal arteriolar fractal dimension, women in the second tertile had a prolonged TTP (FOR: 0.68; 95% CI: 0.51-0.92), as did women in the lowest tertile (FOR: 0.73; 95% CI: 0.55-0.98). Compared with women in the middle tertile of retinal venular branching angle, women in the highest tertile had a borderline prolonged TTP (FOR: 0.75; 95% CI: 0.56-1.02). No other retinal vascular features were significantly associated with TTP.

LIMITATIONS, REASONS FOR CAUTION

We were unable to adjust for other potential confounding factors such as female sexual function (e.g. frequency of sexual intercourse), which might introduce a residual bias. Moreover, even though this is a prospective cohort design, our findings can identify the temporal relationship but not necessarily infer a causal relationship between maternal microvasculature and TTP. Lastly, our study involving mainly Chinese, Malay and Indian ethnicities might not be generalizable to other races or ethnicities.

WIDER IMPLICATIONS OF THE FINDINGS

Suboptimal microcirculation may lead to reduced female fecundability. In the future, in addition to conventional ultrasonographic evaluation of ovarian and uterine physiological function, assessing the retinal microvasculature might be useful for assessment of ovarian age, fertility prediction and endometrial evaluation before assisted reproductive techniques for fertility treatments.

STUDY FUNDING/COMPETING INTEREST(S)

This research is supported by the Singapore National Research Foundation (NRF) under its Translational and Clinical Research (TCR) Flagship Programme and administered by the Singapore Ministry of Health's National Medical Research Council (NMRC) (Singapore-NMRC/TCR/004-NUS/2008; NMRC/TCR/012-NUHS/2014) and Singapore National Medical Research Council Transition Award (NMRC TA/0027/2014). The authors have no competing interests to declare.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov, NCT03531658.

Pluripotency and Growth Factors in Early Embryonic Development of Mammals: A Comparative Approach

The regulation of early events in mammalian embryonic development is a complex process. In the early stages, pluripotency, cellular differentiation, and growth should occur at specific times and these events are regulated by different genes that are expressed at specific times and locations. The genes related to pluripotency and cellular differentiation, and growth factors that determine successful embryonic development are different (or differentially expressed) among mammalian species. Some genes are fundamental for controlling pluripotency in some species but less fundamental in others, for example, Oct4 is particularly relevant in bovine early embryonic development, whereas Oct4 inhibition does not affect ovine early embryonic development. In addition, some mechanisms that regulate cellular differentiation do not seem to be clear or evolutionarily conserved. After cellular differentiation, growth factors are relevant in early development, and their effects also differ among species, for example, insulin-like growth factor improves the blastocyst development rate in some species but does not have the same effect in mice. Some growth factors influence genes related to pluripotency, and therefore, their role in early embryo development is not limited to cell growth but could also involve the earliest stages of development. In this review, we summarize the differences among mammalian species regarding the regulation of pluripotency, cellular differentiation, and growth factors in the early stages of embryonic development.

Manipulating the Epigenome in Nuclear Transfer Cloning: Where, When and How

The nucleus of a differentiated cell can be reprogrammed to a totipotent state by exposure to the cytoplasm of an enucleated oocyte, and the reconstructed nuclear transfer embryo can give rise to an entire organism. Somatic cell nuclear transfer (SCNT) has important implications in animal biotechnology and provides a unique model for studying epigenetic barriers to successful nuclear reprogramming and for testing novel concepts to overcome them. While initial strategies aimed at modulating the global DNA methylation level and states of various histone protein modifications, recent studies use evidence-based approaches to influence specific epigenetic mechanisms in a targeted manner. In this review, we describe-based on the growing number of reports published during recent decades-in detail where, when, and how manipulations of the epigenome of donor cells and reconstructed SCNT embryos can be performed to optimize the process of molecular reprogramming and the outcome of nuclear transfer cloning.

Embryo-Maternal Interactions Underlying Reproduction in Mammals

This Special Issue, “Embryo-Maternal Interactions Underlying Reproduction in Mammals”, gathers a collection of 23 articles, 16 original research articles and 7 up-to-date reviews, providing new findings or summarizing current knowledge on embryo–maternal interactions in seven different mammalian species including humans. Considering the different players involved in these embryo-maternal interactions, articles are mainly focused on one of these different players: the oviduct, the uterus, the embryo or the emergent extracellular vesicles. Additionally, a few articles bring up the impact of reproductive, but also non-reproductive, diseases, as well as stress factors, on the establishment of pregnancy. We hope the readers enjoy this collection of articles and that the knowledge assembled here will support and inspire current and future research investigations. We would like to thank all authors for their contributions to this Special Issue.