Preterm fetal growth restriction is associated with increased parathyroid hormone-related protein expression in the fetal membranes

Acute Histological Chorioamnionitis and Birth Weight in Pregnancies With Preterm Prelabor Rupture of Membranes: A Retrospective Cohort Study

Aim: To assess the association between the birth weight of newborns from pregnancies with preterm prelabor rupture of membranes (PPROM) and the presence of acute histological chorioamnionitis (HCA) with respect to the: i) fetal and maternal inflammatory responses and ii) acute inflammation of the amnion.

Material and Methods: This retrospective cohort study included 818 women with PPROM. A histopathological examination of the placenta was performed. Fetal inflammatory response was defined as the presence of any neutrophils in umbilical cord (histological grades 1–4) and/or chorionic vasculitis (histological grade 4 for the chorionic plate). Maternal inflammatory response was defined as the presence of histological grade 3–4 for the chorion-decidua and/or grade 3 for the chorionic plate and/or grade 1–4 for the amnion. Acute inflammation of the amnion was defined as the presence of any neutrophils in the amnion (histological grade 1–4 for the amnion). Birth weights of newborns were expressed as percentiles derived from INTERGROWTH-21st standards for the i) estimated fetal weight and ii) newborn birth weight.

Results: No difference in percentiles of birth weights of newborns was found among the women with the women with HCA with fetal inflammatory response, with HCA with maternal inflammatory response and those without HCA. Women with HCA with acute inflammation of the amnion had lower percentiles of birth weights of newborns, derived from the estimated fetal weight standards, than women with HCA without acute inflammation of the amnion and those with the absence of HCA in the crude (with acute inflammation: median 46, without acute inflammation: median 52, the absence of HCA: median 55; p = 0.004) and adjusted (p = 0.02) analyses. The same subset of pregnancies exhibited the highest rate of newborns with a birth weight of ≤25 percentile. When percentiles were derived from the newborn weight standards, no differences in birth weights were observed among the subgroups.

Conclusion: Acute inflammation of the amnion was associated with a lower birth weight in PPROM pregnancies, expressed as percentiles derived from the estimated fetal weight standards.

A key moment for TiO2: Prenatal exposure to TiO2 nanoparticles may inhibit the development of offspring

Applications of TiO₂ nanoparticles (NPs) in food, personal care products and industries pose risks on human health, particularly on vulnerable populations including pregnant women and infants. Fetus, deficient in mature defense system, is more susceptible to NPs. Publications on the developmental toxicity of TiO₂ NPs on the maternal-exposed progeny have emerged. This review presents the main exposure routes of TiO₂ NPs during pregnancy, including skin penetration, ingestion and inhalation, followed by transport of TiO₂ NPs to the placenta. Accumulation of TiO₂ NPs in placenta may cause dysfunction in nutrient transfer. TiO₂ NPs can be even transported to the fetus and generate toxicities, such as impairments of nervous and reproductive system, and failure in lung and cardiovascular development. The toxicities rely on the crystalline phase and concentrations, and the main mechanisms include the accumulation of excessive reactive oxygen species, DNA damage, and over-activation of signaling pathways such as MAPK which impairs neurotransmission. Finally, this review remarks on the significance for identifying TiO₂ NPs dosage safe for both mother and fetus, and particular attention should be paid at TiO₂ NPs concentrations safe for mother but toxic to fetus. Importantly, research on the epigenetic trans-generational inheritance of TiO₂ NPs is urgently needed to provide insights for deciding the prospects of TiO₂ NPs applications.

Mechanisms Underpinning Adaptations in Placental Calcium Transport in Normal Mice and Those With Fetal Growth Restriction

Fetal delivery of calcium, via the placenta, is crucial for appropriate skeletal mineralization. We have previously demonstrated that maternofetal calcium transport, per gram placenta, is increased in the placental specific insulin-like growth factor 2 knockout mouse (P0) model of fetal growth restriction (FGR) compared to wild type littermates (WTL). This effect was mirrored in wild-type (WT) mice comparing lightest vs. heaviest (LvH) placentas in a litter. In both models increased placental calcium transport was associated with normalization of fetal calcium content. Despite this adaptation being observed in small normal (WT), and small dysfunctional (P0) placentas, mechanisms underpinning these changes remain unknown. Parathyroid hormone-related protein (PTHrP), elevated in cord blood in FGR and known to stimulate plasma membrane calcium ATPase, might be important. We hypothesized that PTHrP expression would be increased in LvH WT placentas, and in P0 vs. WTL. We used calcium pathway-focused PCR arrays to assess whether mechanisms underpinning these adaptations in LvH WT placentas, and in P0 vs. WTL, were similar. PTHrP protein expression was not different between LvH WT placentas at E18.5 but trended toward increased expression (139%; P = 0.06) in P0 vs. WTL. PCR arrays demonstrated that four genes were differentially expressed in LvH WT placentas including increased expression of the calcium-binding protein calmodulin 1 (1.6-fold; P < 0.05). Twenty-four genes were differentially expressed in placentas of P0 vs. WTL; significant reductions were observed in expression of S100 calcium binding protein G (2-fold; P < 0.01), parathyroid hormone 1 receptor (1.7-fold; P < 0.01) and PTHrP (2-fold; P < 0.05), whilst serum/glucocorticoid-regulated kinase 1 (SGK1), a regulator of nutrient transporters, was increased (1.4 fold; P < 0.05). Tartrate resistant acid phosphatase 5 (TRAP5 encoded by Acp5) was reduced in placentas of both LvH WT and P0 vs. WTL (1.6- and 1.7-fold, respectively; P < 0.05). Signaling events underpinning adaptations in calcium transport are distinct between LvH placentas of WT mice and those in P0 vs. WTL. Calcium binding proteins appear important in functional adaptations in the former whilst PTHrP and SGK1 are also implicated in the latter. These data facilitate understanding of mechanisms underpinning placental calcium transport adaptation in normal and growth restricted fetuses.

UNDERSTANDING THE PLACENTAL AETIOLOGY OF FETAL GROWTH RESTRICTION; COULD THIS LEAD TO PERSONALIZED MANAGEMENT STRATEGIES?

Fetal growth restriction (FGR) is defined as the failure of a fetus to attain its full genetic growth potential. It is a leading cause of stillbirth, prematurity, cerebral palsy and perinatal mortality. Small size at birth increases surviving infants’ lifelong risk of adverse health outcomes associated with the metabolic syndrome. The pathophysiology of abnormal fetal growth is extremely complex and incompletely understood, with a plethora of genetic, signalling and metabolic candidates under investigation, many of which may result in abnormal structure and function of the placenta. In contrast to, or maybe because of, the underlying complexities of FGR, the strategies clinicians have for identifying and managing this outcome are conspicuously limited. Current clinical practice is restricted to identifying pregnancies at risk of FGR, and when FGR is detected, using intensive monitoring to guide the timing of delivery to optimise fetal outcomes. Abnormal Doppler indices in the umbilical artery are strongly associated with poor perinatal outcomes and are currently the “gold standard” for clinical surveillance of the growth-restricted fetus.

Survival and size are differentially regulated by placental and fetal PKBalpha/AKT1 in mice

The importance of placental circulation is exemplified by the correlation of placental size and blood flow with fetal weight and survival during normal and compromised human pregnancies in such conditions as preeclampsia and intrauterine growth restriction (IUGR). Using noninvasive magnetic resonance imaging, we evaluated the role of PKBalpha/AKT1, a major mediator of angiogenesis, on placental vascular function. PKBalpha/AKT1 deficiency reduced maternal blood volume fraction without affecting the integrity of the fetomaternal blood barrier. In addition to angiogenesis, PKBalpha/AKT1 regulates additional processes related to survival and growth. In accordance with reports in adult mice, we demonstrated a role for PKBalpha/AKT1 in regulating chondrocyte organization in fetal long bones. Using tetraploid complementation experiments with PKBalpha/AKT1-expressing placentas, we found that although placental PKBalpha/AKT1 restored fetal survival, fetal PKBalpha/AKT1 regulated fetal size, because tetraploid complementation did not prevent intrauterine growth retardation. Histological examination of rescued fetuses showed reduced liver blood vessel and renal glomeruli capillary density in PKBalpha/Akt1 null fetuses, both of which were restored by tetraploid complementation. However, bone development was still impaired in tetraploid-rescued PKBalpha/Akt1 null fetuses. Although PKBalpha/AKT1-expressing placentas restored chondrocyte cell number in the hypertrophic layer of humeri, fetal PKBalpha/AKT1 was found to be necessary for chondrocyte columnar organization. Remarkably, a dose-dependent phenotype was exhibited for PKBalpha/AKT1 when examining PKBalpha/Akt1 heterozygous fetuses as well as those complemented by tetraploid placentas. The differential role of PKBalpha/AKT1 on mouse fetal survival and growth may shed light on its roles in human IUGR.

Production and characterisation of gilthead sea bream (Sparus auratus) recombinant parathyroid hormone related protein

The production and purification of gilthead sea bream recombinant parathyroid hormone related protein [sbPTHrP(1-125)] using an Escherichia coli system and one step purification process with continuous elution gel electrophoresis is reported. The cDNA encoding sbPTHrP(1-125) was cloned into a prokaryotic expression vector pET-11a. The recombinant plasmid was used to transfect E. coli BL21(DE3) pLysS and sbPTHrP(1-125) synthesis was induced by addition of 1mM isopropyl-beta-d-thiogalactopyranoside. The rapid one step isolation method gave pure sbPTHrP(1-125) as judged by SDS-PAGE and yielded up to 40mg/L of culture medium (3.3mg protein/g of bacteria). The bioactivity of recombinant sbPTHrP(1-125) assessed using an in vitro scale bioassay was found to be equipotent to PTHrP(1-34) in stimulating cAMP accumulation. Assessment of the immunological reactivity of the isolated protein by Western blot revealed it cross-reacts with antisera specific for the N-terminal and C-terminal region of PTHrP. In a radioimmunoassay specific for piscine N-terminal (1-34aa) PTHrP, the recombinant sbPTHrP(1-125) was equipotent with PTHrP(1-34) in displacing labelled (125)I-PTHrP(1-36) PTHrP from the antisera. The availability of recombinant sbPTHrP will allow the development of region specific assays and studies aimed at defining post-secretory processing of this protein and its biological activity in fish.

Expression of GLUT12 in the fetal membranes of the human placenta

The aim of this study was to characterize the expression of the novel glucose transporter GLUT12 in the fetal membranes of the human placenta. RT-PCR and Western blotting of extracts of amnion and choriodecidua from four normal term placentas identified GLUT12 mRNA and protein expression. In all four samples the signals for GLUT12 were markedly stronger in the choriodecidua than in the amnion, whereas the signals for GLUT1, a glucose transporter know to be expressed in fetal membranes, were similar for the two tissues. In further studies, paraffin sections of fetal membranes were analyzed by immunohistochemistry with GLUT12 and GLUT1-specific polyclonal antibodies. GLUT12 immunoreactivity was localized predominantly to the trophoblast cells in the chorion and to a lesser extent to decidual cells and to epithelial and fibroblast cells of the amnion. GLUT1 was localized to chorionic trophoblast cells and amniotic epithelial and fibroblast cells. GLUT12 expression was predominantly cytoplasmic, whereas GLUT1 was associated with the membrane of the cells. These results show that GLUT12 is expressed in cells of human fetal membranes and suggest that GLUT12 may play a role in the facilitation of glucose transport into these cells.

Uteroplacental restriction in the rat impairs fetal growth in association with alterations in placental growth factors including PTHrP

During pregnancy, parathyroid hormone-related protein (PTHrP) is one of many growth factors that play important roles to promote fetal growth and development, including stimulation of placental calcium transport. Angiotensin II, acting through the AT1a receptor, is also known to promote placental growth. We examined the effects of bilateral uterine artery and vein ligation (restriction), which mimics placental insufficiency in humans, on growth, intrauterine PTHrP, placental AT1a, and pup calcium. Growth restriction was surgically induced on day 18 of pregnancy in Wistar-Kyoto female rats by uterine vessel ligation. Uteroplacental insufficiency reduced fetal body weight by 15% and litter size ( P < 0.001) compared with the control rats with no effect on placental weight or amniotic fluid volume. Uteroplacental insufficiency reduced placental PTHrP content by 46%, with increases in PTHrP (by 2.6-fold), parathyroid hormone (PTH)/PTHrP receptor (by 11.6-fold), and AT1a (by 1.7-fold) relative mRNA in placenta following restriction compared with results in control ( P < 0.05). There were no alterations in uterine PTHrP and PTH/PTHrP receptor mRNA expression. Maternal and fetal plasma PTHrP and calcium concentrations were unchanged. Although fetal total body calcium was not altered, placental restriction altered perinatal calcium homeostasis, as evidenced by lower pup total body calcium after birth ( P < 0.05). The increased uterine and amniotic fluid PTHrP ( P < 0.05) may be an attempt to compensate for the induced impaired placental function. The present study demonstrates that uteroplacental insufficiency alters intrauterine PTHrP, placental AT1a expression, and perinatal calcium in association with a reduction in fetal growth. Uteroplacental insufficiency may provide an important model for exploring the early origins of adult diseases.

ATP dependent Ca2+ transport across basal membrane of human syncytiotrophoblast in pregnancies complicated by intrauterine growth restriction or diabetes

Neonates born after pregnancies complicated by diabetes or intrauterine growth restriction (IUGR) have increased incidence of hypocalcaemia. Furthermore, IUGR is associated with reduced bone mineralization in infancy and osteoporosis in adult life. We tested the hypothesis that placental calcium transport is altered in these pregnancy complications. Transport of calcium into syncytiotrophoblast basal plasma membrane (BM) vesicles was studied by rapid filtration and protein expression of Ca(2+) ATPase by Western blot. In IUGR Ca(2+) ATPase activity was increased by 48 per cent (n=13; P< 0.05) whereas protein expression was 15 per cent lower (n=13; P< 0.05) than in controls (n=16). Basal membrane ATP dependent calcium transport was unaltered in gestational diabetes (GDM) but increased by 54 per cent in insulin dependent diabetes (IDDM) compared to controls (P< 0.05; n =14). Diabetes did not affect Ca(2+) ATPase expression in BM. We have previously shown that the mid-molecular fragment of parathyroid hormone related peptide (PTHrP midmolecule) stimulates BM Ca(2+) ATPase in vitro. PTHrP midmolecule concentrations in umbilical cord plasma were measured using radioimmunoassay. The concentrations in umbilical cord plasma were increased in IUGR, but unaltered in diabetes. In conclusion, placental calcium pump is activated in IUGR and IDDM, which may be secondary to increased foetal calcium demand. We speculate that PTHrP midmolecule may be one mechanism for activating BM Ca(2+) ATPase in IUGR.

Parathyroid hormone-related protein and its receptors: nuclear functions and roles in the renal and cardiovascular systems, the placental trophoblasts and the pancreatic islets

The cloning of the so-called 'parathyroid hormone-related protein' (PTHrP) in 1987 was the result of a long quest for the factor which, by mimicking the actions of PTH in bone and kidney, is responsible for the hypercalcemic paraneoplastic syndrome, humoral calcemia of malignancy. PTHrP is distinct from PTH in a number of ways. First, PTHrP is the product of a separate gene. Second, with the exception of a short N-terminal region, the structure of PTHrP is not closely related to that of PTH. Third, in contrast to PTH, PTHrP is a paracrine factor expressed throughout the body. Finally, most of the functions of PTHrP have nothing in common with those of PTH. PTHrP is a poly-hormone which comprises a family of distinct peptide hormones arising from post-translational endoproteolytic cleavage of the initial PTHrP translation products. Mature N-terminal, mid-region and C-terminal secretory forms of PTHrP are thus generated, each of them having their own physiologic functions and probably their own receptors. The type 1 PTHrP receptor, binding both PTH(1-34) and PTHrP(1-36), is the only cloned receptor so far. PTHrP is a PTH-like calciotropic hormone, a myorelaxant, a growth factor and a developmental regulatory molecule. The present review reports recent aspects of PTHrP pharmacology and physiology, including: (a) the identification of new peptides and receptors of the PTH/PTHrP system; (b) the recently discovered nuclear functions of PTHrP and the role of PTHrP as an intracrine regulator of cell growth and cell death; (c) the physiological and developmental actions of PTHrP in the cardiovascular and the renal glomerulo-vascular systems; (d) the role of PTHrP as a regulator of pancreatic beta cell growth and functions, and, (e) the interactions of PTHrP and calcium-sensing receptors for the control of the growth of placental trophoblasts. These new advances have contributed to a better understanding of the pathophysiological role of PTHrP, and will help to identify its therapeutic potential in a number of diseases.

The spontaneously hypertensive rat fetus, not the mother, is responsible for the reduced amniotic fluid PTHrP concentrations and growth restriction

Intrauterine parathyroid hormone-related protein (PTHrP) concentrations are reduced in association with growth restriction in the spontaneously hypertensive rat (SHR) compared to those of its normotensive control, the Wistar Kyoto (WKY) rat, implicating PTHrP as a pivotal fetal growth factor. The aim of this study was to examine, by embryo cross-transplanation between SHR and WKY, whether the mother, fetus, or both, are responsible for the suppressed SHR amniotic fluid PTHrP. One-day-old SHR embryos were gestated in either an SHR (SHR-in-SHR) or WKY (SHR-in-WKY) surrogate, similarly one-day-old WKY embryos were gestated in either an SHR (WKY-in-SHR) or WKY (WKY-in-WKY) mother. At 20 days gestation, maternal plasma and amniotic fluid samples were collected and assayed for PTHrP concentrations. Data were analysed by two-way ANOVA (mean+/-sem, n=5-9 mothers/group). There were no differences in litter number or maternal plasma PTHrP concentrations. Fetal weight (P< 0.009), fetal/placental weight ratio (P< 0.004) and amniotic fluid PTHrP concentrations (P< 0.001) were lower and amniotic fluid volume (P< 0.0001) was higher with an SHR fetus compared to the WKY fetus irrespective of maternal strain. Thus, the SHR fetus is growth restricted and has suppressed amniotic fluid PTHrP, which are largely determined by the fetus or gestational tissues and are independent of maternal hypertension or maternal PTHrP. We suggest that the low SHR amniotic fluid PTHrP may play a role in the development of SHR growth restriction.