Immunohistochemical localization of insulin-like growth factors I and II at the primary implantation site in the Rhesus monkey

Preimplantation Endometrial Transcriptomics in Natural Conception Cycle of the Rhesus Monkey

There is no report on preimplantation phase endometrial transcriptomics in natural conception cycles of primates. In the present study, the whole-genome expression array of endometrium on Days 2, 4, and 6 post-ovulation (pov) in proven natural conception (Group 1; n = 12) and non-mated, ovulatory (Group 2; n = 12) cycles of rhesus monkeys was examined, compared, and validated. Of fifteen (15) genes showing differential expression (>2-fold; pFDR < 0.05), six genes (CHRND, FOXD3, GJD4, MAPK8IP3, MKS1, and NUP50) were upregulated, while eight genes (ADCY5, ADIPOR1, NNMT, PATL1, PIGV, TGFBR2, TOX2, and VWA5B1) were down regulated on Day 6 pov as compared to Day 2 pov in conception cycles. On Day 6 pov, four genes (ADCY5, NNMT, TOX2, and VWA5B1) were down regulated, and AVEN was upregulated in conception cycles compared with the non-conception cycle. These observations were orthogonally validated at protein expression level. Group-specifically expressed unique genes in conception cycles influence the process of induction of immune-tolerance, while the genes expressed in both groups influence processes of protein targeting and metabolism. A triad of timed-actions of progesterone, seminal plasma, and preimplantation embryo putatively regulate several input molecules to CREB, NF-kB, and STAT regulatory networks during secretory phase towards evolution of endometrial receptivity in the rhesus monkey.

A historical review of blastocyst implantation research

Research development on blastocyst implantation was reviewed in three sections: primate implantation, ungulate farm animal implantation, and the general process of blastocyst implantation in small rodents. Future research directions of this area are suggested.

An integrative view on the physiology of human early placental villi

The placenta is an indispensable organ for intrauterine protection, development and growth of the embryo and fetus. It provides tight contact between mother and conceptus, enabling the exchange of gas, nutrients and waste products. The human placenta is discoidal in shape, and bears a hemo-monochorial interface as well as villous materno-fetal interdigitations. Since Peter Medawar's astonishment to the paradoxical nature of the mother-fetus relationship in 1953, substantial knowledge in the domain of placental physiology has been gathered. In the present essay, an attempt has been made to build an integrated understanding of morphological dynamics, cell biology, and functional aspects of genomic and proteomic expression of human early placental villous trophoblast cells followed by a commentary on the future directions of research in this field.

IGF2, IGF binding protein 1, and matrix metalloproteinases 2 and 9 in implantation-stage endometrium following immunoneutralization of vascular endothelial growth factor in the rhesus monkey

Blastocyst implantation in the rhesus monkey is inhibited by administration of antibody against vascular endothelial growth factor (VEGF) A during peri-implantation period with no change in the circulatory concentrations of estradiol, progesterone, and VEGF. In this study, we have investigated the effect of administration of a MAB to VEGFA on days 5 and 10 after ovulation upon the mRNA expression, immunopositive protein expression, and immunohistological localization of IGF2, IGF binding protein 1 (IGFBP1) and matrix metalloproteinases (MMPs) 2 and 9 in the implantation-stage endometrium collected on day 13 after ovulation from fecund cycles of rhesus monkeys. The comparison between isotype-matched IgG (control; n=8)- and VEGF antibody (VEGF Mab; n=8)-treated animals revealed higher (P<0.05) IGF2 in lacunar and villous syncytiotrophoblasts, trophoblast cell columns, migrating extravillous trophoblast cells, and endovascular trophoblast cells in control animals, but with no change in the various cell types of maternal endometrium between the two groups. No change in IGFBP1 expression in the endometrium was observed between the two groups. MMPs 2 and 9 were detected in syncytiotrophoblast in lacunae and villi, trophoblast cell columns, and extravillous trophoblast cells in control samples. MMP9 transcript expression in maternal endometrium and its immunopositivity in endometrial stroma and trophoblast cells were lower (P<0.05) with no change in MMP2 level in VEGF Mab-exposed samples compared with those in control samples. A functional network involving VEGF, IGF2, and MMP9 in early placental trophoblast cells and maternal endometrium appears to be important for normal placentation.

Maternal-placental insulin-like growth factor (IGF) signaling and its importance to normal embryo-fetal development

As background for an antibody-based therapeutic program against the IGF receptor, we undertook a review of available information on the early pregnancy-specific regulation and localization of IGFs, IGF-binding proteins (BPs), IGFBP-specific proteases, and the type 1 IGF receptor relative to placental maintenance, function of placental nutrient transporters, placental cellular differentiation/turnover/apoptosis, and critical hormone signaling needed to maintain pregnancy. Possible adverse outcomes of altered IGF signaling include prenatal loss, fetal growth retardation, and maldevelopment are also discussed. It appears that the IGF axes in both the conceptus and mother are important for normal embryo-fetal growth. Thus, all molecules (i.e., both small and large) that disrupt the IGF axis could be expected to have some degree of fetal consequences.

Three-dimensional power Doppler sonography of the (sub)endometrium and angiogenic cytokine concentrations

The aim of this study was to determine the correlation between three-dimensional power Doppler sonography (3D-PDS) of the (sub)endometrium and concentrations of angiogenic cytokines in patients attending an IVF programme. A total of 42 patients was included in a prospective, non-randomized clinical study. 3D-PDS of the (sub)endometrium was performed on the day of oocyte aspiration, with and without contrast agent. Quantitative assessment included the following 3D Doppler parameters: vascularization index, flow intensity, and vascularization flow index. On the same day, concentrations of oestradiol (serum only), vascular endothelial growth factor (VEGF), insulin-like growth factor (IGF) 1, IGF-binding protein 3 (IGFBP-3) and leptin were determined in the serum and in the follicular fluid. All 3D-PDS indices were significantly higher with contrast enhancement (P < 0.05). Follicular fluid concentrations of VEGF and IGFBP-3, as well as serum concentrations of leptin, showed significant P-values when correlated with (sub)endometrial Doppler indices. A weak linear dependency appeared between flow intensity and VEGF and leptin. Furthermore, weak dependencies were apparent between 3D Doppler parameters and high follicular fluid concentrations of VEGF and IGFBP-3. It is concluded that there is only little evidence for an association between (sub)endometrial Doppler indices as assessed by 3D-PDS and concentrations of angiogenic cytokines.

Immunolocalization of insulin-like growth factor I (IGF-I) during preimplantation in rat uterus

OBJECTIVE

The aim of this study was to determine the insulin-like growth factor (IGF-I) immunolocalization in rat uterus at preimplantation period.

DESIGN

The tissue samples were examined from pregnant animals between gestational day 1 and 5 using immunocytochemistry.

RESULTS

While both the uterine luminal epithelium and the glandular epithelium were stained strongly from gestational day 1 - 3 by IGF-I antibody, the IGF-I immunoreactivity was moderate in myometrium and capillary endothelium. At this period, the IGF-I immunoreactivity was weakly present in a few endometrial stromal cells. At day 4, while IGF-I immunostaining intensity was particularly decreased in the basal domains of uterine luminal epithelium and glandular epithelium, it was similar to the first 3 days of gestation in myometrium and capillary endothelium. The endometrial vascularization and the number of stromal cells immunoreacting with IGF-I increased. The differentiation of stromal cells into decidual cells was seen at gestational day 5 and IGF-I was strongly expressed in the decidualizing cells. The IGF-I immunoreactivity in uterine luminal epithelium and glandular epithelium was similar to gestational day 4. IGF-I immunoreactivity was strongly detected in all of endometrial stromal cells.

CONCLUSION

These results indicate that IGF-I expression in the rat uterus changes in the early pregnancy process and increase toward to day when implantation will be initiated.

Nitric oxide in blastocyst implantation in the rhesus monkey

Successful blastocyst implantation depends on the interaction between cells of maternal endometrium and conceptus, as well as adequate blood supply to the site of blastocyst implantation. Nitric oxide (NO) generally plays a significant role in the local regulation of vascular physiology in a variety of mammalian tissue systems, however, its role in blastocyst implantation and placentation in the primate is not known. The aim of the present study was to examine: (i) NADH-diaphorase activity and expression of three isoforms of nitric oxide synthase (NOS), namely endothelial NOS (eNOS), inducible NOS (iNOS) and neuronal NOS (nNOS) in pre-implantation stage monkey embryos, morula (n= 4) and blastocyst (n= 10), as well as, in different compartments of conceptus and maternal endometrium at primary implantation sites during lacunar (n= 6) and villous (n= 9) stages of placentation in the rhesus monkey, and (ii) the potential anti-nidatory effect of vaginal administration of NOS inhibitor during the peri-implantation period of conception cycles in rhesus monkeys. Pre-implantation stage blastocysts exhibited marked NADPH-diaphorase activity along with immunopositive iNOS mainly in the inner cell mass. During the lacunar stage, marked eNOS expression was observed in cytotrophoblast cells lining the embryonic cavity. However, cytotrophoblast cells lining villi, forming columns, and constituting anchoring villi expressed all the three isoforms of NOS in villous placenta stage tissue. During the lacunar stage, eNOS and iNOS protein expressions were observed in epithelial and decidual cells of endometrium. As gestation advanced, mRNAs for all three isoforms of NOS were observed to increase in epithelial and decidual cells, however, with no marked change in protein expression. Vaginal administration of a NOS inhibitor (NG-nitro-l-arginine methyl ester, L-NAME, 4, 6, and 8 mg/kg body weight or aminoguanidine, AG, 4 mg/kg body weight) during days 6 to 12 after ovulation resulted in pregnancy failure in a higher number of animals (L-NAME: 8 confirmed pregnancies in 25 animals; AG: 2 confirmed pregnancies in 8 animals) compared with control animals (5 pregnancies in 7 animals). It appears that NO may play an important role in the establishment of pregnancy in the rhesus monkey.

Immunohistological localization of insulin-like growth factor binding protein-1 in primary implantation sites and trauma-induced deciduomal tissues of the rhesus monkey

We have earlier demonstrated that there is a close similarity in the temporo-spatial pattern in the onset of oedema, epithelial-plaque transformation, stromal decidualization and influx of granulated lymphocytes in artificially trauma-induced deciduomal endometrium with such events in maternal endometrium at the primary implantation site during early stages of pregnancy in the rhesus monkey. In the present study, we have immunohistochemically examined whether the pattern of insulin-like growth factor-binding protein 1 (IGFBP-1) protein expression in conceptus tissue and maternal endometrium during lacunae and villous placenta stages of gestation in the rhesus monkey is developmental stage-specific and whether a discernible difference exists in the temporo-spatial characteristics of IGFBP-1 protein expression between conceptus associated implantation-decidualization and trauma induced deciduoma in the rhesus monkey. Trophoblast cells failed to exhibit IGFBP-1 immunopositive staining at any stage of implantation-placentation studied. Epithelial cells in plaque acini, endothelial cells, and vascular smooth muscle also did not show any immunopositive staining for IGFBP-1 in samples of primary implantation sites and trauma-induced deciduoma. Maternal endometrial epithelial and stromal-decidual cells however exhibited a temporal and spatial pattern of IGFBP-1 expression in cell-type specific manner and clear distinctions were observed between conception and deciduoma samples. Our results suggest that IGFBP-1 expression is highly tissue and development-specific and that conceptus-derived signals are necessary to initiate the glandular expression of IGFBP-1 during the early stage of gestation.

Immunohistochemical localization of leukemia inhibitory factor, interleukins 1 and 6 at the primary implantation site in the rhesus monkey

Blastocyst implantation and placentation involve localized inflammatory type of responses at and around the site of nidation. In the present study, the likely involvement of inflammatory cytokines, namely, leukemia inhibitory factor (LIF), interleukins 1 alpha and 1 beta (IL-1alpha and IL-1beta) and IL-6 at the primary implantation site of the rhesus monkey was examined immunocytochemically during lacunar (n=6) and villous (n=8) stages of gestation. Trophoblast cells and extraembryonic mesenchymal cells were immunopositive for LIF and IL-1alpha. The distribution of IL-1beta and IL-6 in trophoblast cells was low in lacunar stage samples, however, a higher degree of immunopositivity for IL-6 was observed in villous stage samples. Decidual cells were immunopositive for all the cytokines studied. In lacunar stage samples, plaque cells adjacent to implanted nidus were immunopositive for all the cytokines examined, and the degree of their immunoprecipitation increased, except that of IL-1beta, during the villous stage. Luminal and glandular epithelial cells were immunopositive for LIF, IL-1alpha, IL-1beta and IL-6 in lacunar and in villous stage samples. LIF immunopositivity was detected in endothelial cells of blood vessels within and below chorionic plate and cytotrophoblast shell, while vascular smooth muscle cells were positive for all the cytokines studied. The temporo-spatial characteristics of LIF, IL-1alpha, IL-1beta and IL-6 protein expressions in primary implantation sites of the rhesus monkey suggest that these pro-inflammatory cytokines play specific roles in regulating trophoblast cell proliferation, differentiation, invasion and associated maternal tissue remodelling during early gestation.

Comparative Biology of the IGF System in Endometrium, Decidua, and Placenta, and Clinical Implications for Foetal Growth and Implantation Disorders

The insulin like growth factors and their binding proteins appear to play a central role during implantation and establishment of pregnancy in all species studied. Although there are similarities among species in the cell types that express IGFs and IGFBPs and their regulation during implantation and pregnancy, there are also significant differences. Understanding of the role of the IGF system in placental function in the human is of immense clinical importance, because serious complications of pregnancy such as intrauterine growth restriction and pre-eclampsia are thought to be associated with alterations in IGF system during early pregnancy and later in gestation. Research in laboratory and domestic animals, including transgenic and gene targeting studies in mice, has significantly improved our understanding of the role of IGF system in placental and foetal development. This paper reviews the diversity in the expression and regulation of IGF system in the decidua and placenta at the foetal-maternal interface in the human and different animal species, which may benefit in directing future studies in understanding of various complications of human pregnancy.

IGF-1 in gynaecology and obstetrics: update 2002

Recent discoveries on endocrine, paracrine and autocrine involvement of insulin-like growth factor-1 (IGF-1) in the proliferation of many tissues raised the attention of its role in reproduction and in the growth of various cancers as well as of benign proliferations. The intention of this article is to focus on IGF-1 in the field of gynaecology. Perimenopausal women who exhibit high IGF-1 and low IGF binding protein (IGFBP) levels, like IGFBG-3, have an increased risk of developing breast cancer. A higher risk for cervical, ovarian and endometrial cancer is related to high IGF-1 levels in post- and premenopausal women. It has been shown that myomas, by far the most common benign uterine tumor in women, grow in the presence of IGF-1, in vitro as well as in vivo. Studies show that IGF-1 is involved in the differentiation of various reproductive tissues, like endometrium and ovarian tissues. Patients suffering from polycystic ovary syndrome (PCO) frequently show insulin resistance accompanied by an increase of IGF-1 in plasma. Plasma IGF-1 levels are higher in cases of severe endometriosis, however, in endometriosis and in PCO IGF levels locally in the endometrium are reduced, what might explain infertility. Recently, it was shown that IGF facilitates the implantation of the human embryo in the endometrium during IVF. Implantation is a paradox where different immune systems have to collaborate to make implantation and survival of the pregnancy possible. IGF seems to be the starter molecule so that the two epithelia can fuse. A disturbance can result in complications during pregnancy i.e. spontaneous miscarriage, preeclampsia as well as defects of the embryo. Therefore, IGF is a useful marker in successful pregnancy as well. A better mechanistic understanding of IGF-1 action on the cellular level not only provides more elegant mechanistic explanations for the scientist, but the practitioner might find it interesting to utilize its diagnostic potential as a marker for various diseases. The relation between systemic IGF levels and local tissue IGF-1 levels has not yet been determined for all conditions.