High-throughput mRNA-seq atlas of human placenta shows vast transcriptome remodeling from first to third trimester†

The placenta, composed of chorionic villi, changes dramatically across gestation. Understanding differences in ongoing pregnancies are essential to identify the role of chorionic villi at specific times in gestation and develop biomarkers and prognostic indicators of maternal-fetal health. The normative mRNA profile is established using next-generation sequencing of 124 first trimester and 43 third trimester human placentas from ongoing healthy pregnancies. Stably expressed genes (SEGs) not different between trimesters and with low variability are identified. Differential expression analysis of first versus third trimester adjusted for fetal sex is performed, followed by a subanalysis with 23 matched pregnancies to control for subject variability using the same genetic and environmental background. Placenta expresses 14,979 polyadenylated genes above sequencing noise (transcripts per million > 0.66), with 10.7% SEGs across gestation. Differentially expressed genes (DEGs) account for 86.7% of genes in the full cohort [false discovery rate (FDR) < 0.05]. Fold changes highly correlate between the full cohort and subanalysis (Pearson = 0.98). At stricter thresholds (FDR < 0.001, fold change > 1.5), there remains 50.1% DEGs (3353 upregulated in first and 4155 upregulated in third trimester). This is the largest mRNA atlas of healthy human placenta across gestation, controlling for genetic and environmental factors, demonstrating substantial changes from first to third trimester in chorionic villi. Specific differences and SEGs may be used to understand the specific role of the chorionic villi throughout gestation and develop first trimester biomarkers of placental health that transpire across gestation, which can be used for future development of biomarkers for maternal-fetal health.

Changes in Serum Concentrations of Bone Turnover Markers in Healthy Pregnant Women

Background

Changes in bone metabolism during pregnancy have not received sufficient attention because of the lack of effective screening tools. Bone turnover markers (BTMs) could reflect the changes of bone metabolism. Currently, reference intervals for bone metabolism during normal pregnancy are inconclusive. This study aimed to determine reference intervals for BTMs in pregnant women taking prenatal care and to facilitate clinical research on diseases affecting bone metabolism during pregnancy.

Methods

We surveyed 120 low-risk pregnant women attending routine antenatal care from January 2020 to March 2020. The serum levels of procollagen type I N-propeptide (PINP), N-terminal osteocalcin (N-MID), and C-terminal telopeptide of type I collagen (β-CTX) were measured in the first trimester (<13 weeks), second trimester (14-27 weeks), and third trimester (>28 weeks). Reference intervals for BTMs during pregnancy were analyzed. The Kruskal-Wallis test and paired t-test are used to analyze differences between groups. Spearman correlation coefficients expressed the measure of linear association.

Results

The bone resorption marker β-CTX in third trimester increases compared to the first trimester and the second trimester (P < 0.001, P < 0.001). The bone formation markers PINP and N-MID were decreased from the first trimester to the second trimester (P = 0.01, P < 0.001) and then raised from the second trimester to the third trimester (P < 0.001, P < 0.001). Two indices of bone turnover rate, β-CTX/PINP and β-CTX/N-MID, were increased from the first trimester to the second trimester (P < 0.001, P < 0.001) and then decreased from the second trimester to the third trimester (P = 0.02, P < 0.001).

Conclusion

This study established reference intervals for BTMs in pregnant women and observed the changes in BTMs during the different trimesters of pregnancy. The present findings can help in clinical monitoring of the effects of pregnancy diseases on the bone metabolism of pregnant women.

High-throughput mRNA-seq atlas of human placenta shows vast transcriptome remodeling from first to third trimester

Background

The placenta, composed of chorionic villi, changes dramatically across gestation. Understanding differences in ongoing pregnancies are essential to identify the role of chorionic villi at specific times in gestation and develop biomarkers and prognostic indicators of maternal- fetal health.

Methods

The normative mRNA profile is established using next-generation sequencing of 124 first trimester and 43 third trimester human placentas from ongoing healthy pregnancies. Stably expressed genes not different between trimesters and with low variability are identified. Differential expression analysis of first versus third trimester adjusted for fetal sex is performed, followed by a subanalysis with 23 matched pregnancies to control for subject variability using the same genetic and environmental background.

Results

Placenta expresses 14,979 mRNAs above sequencing noise (TPM>0.66), with 1,545 stably expressed genes across gestation. Differentially expressed genes account for 86.7% of genes in the full cohort (FDR<0.05). Fold changes highly correlate between the full cohort and subanalysis (Pearson = 0.98). At stricter thresholds (FDR<0.001, fold change>1.5), there are 6,941 differentially expressed protein coding genes (3,206 upregulated in first and 3,735 upregulated in third trimester).

Conclusion

This is the largest mRNA atlas of healthy human placenta across gestation, controlling for genetic and environmental factors, demonstrating substantial changes from first to third trimester in chorionic villi. Specific differences and stably expressed genes may be used to understand the specific role of the chorionic villi throughout gestation and develop first trimester biomarkers of placental health that transpire across gestation, which can be used for future development of biomarkers in maternal-fetal disease.

The Hepatobiliary System: An Overview of Normal Function and Diagnostic Testing in Pregnancy

Pregnancy is associated with physiological adaptions that affect every organ system. Changes in liver function in pregnancy have important effects on nutrient metabolism, protein synthesis, and the biotransformation of substances in preparation for excretion. A clear understanding of the anatomic and functional changes of the hepatobiliary system is necessary for the diagnosis and evaluation of disease, as well as understanding how these changes predispose women to pregnancy-specific hepatic conditions. In this review, the effect of gestational changes in hepatobiliary function on laboratory tests and the role of diagnostic imaging of the liver and gallbladder in pregnancy will be discussed.

Early maternal circulating alkaline phosphatase with subsequent gestational diabetes mellitus and glucose regulation: a prospective cohort study in China

PURPOSE

Emerging clinical evidence has implied that alkaline phosphatase (ALP) may contribute to gestational diabetes mellitus (GDM). However, there were no studies to reveal the independent and prospective associations between ALP and GDM. Our aim was to explore the independent and prospective associations between early maternal ALP level and GDM risk and glucose regulation.

METHODS

In a prospective cohort study with 2073 singleton mothers at four maternity units in China, maternal serum ALP levels were measured before 20 gestational weeks. Using logistic regression, we analyzed the relationship between maternal ALP level and risk of GDM. We further explored the relationships of ALP level to fasting blood glucose (FBG), 1-h and 2-h post-load blood glucose (1-h, 2-h PBG) with multiple linear regression. Finally, we analyzed the association between maternal ALP level and isolated impaired fasting glucose (i-IFG) and isolated impaired glucose tolerance (i-IGT) risk.

RESULTS

The maximum value of maternal ALP level was 90 U/L, within the normal range. After adjustment for confounding factors, the odds ratio (ORs) of GDM increased linearly with ALP level (p for overall association = 0.002, p for nonlinear association = 0.799), with the OR comparing the highest versus lowest quartile of 2.47 (95% CI 1.47, 4.15). Moreover, each additional of 10 U/L ALP level was associated with a 2% higher FBG (p = 0.043) and a 12% higher 1-h PBG (p = 0.004). Higher ALP level also increased the risk of i-IFG (OR 3.73, 95% CI 1.17-11.86) and i-IGT (OR 2.03, 95% CI 1.07-3.84).

CONCLUSIONS

Even within the upper limit of normal, higher early maternal ALP level could increase the risk of GDM. Moreover, both FBG and PBG were increased with early maternal ALP.

Gestational age-specific reference intervals for 15 biochemical measurands during normal pregnancy in China

Aims

Physiological changes that occur during pregnancy can influence biochemical parameters. Therefore, using reference intervals based on specimens from non-pregnant women to interpret laboratory results during pregnancy may be inappropriate. This study aimed to establish the essential reference intervals for a range of analytes during pregnancy.

Methods

A cross-sectional study was performed in 13,656 healthy pregnant and 2634 non-pregnant women. Fifteen biochemical measurands relating to renal and hepatic function were analysed using an Olympus AU5400 analyzer (Olympus, Tokyo, Japan). All the laboratory results were checked for outliers using Dixon’s test. Reference intervals were established using a non-parametric method.

Results

Alanine aminotransferase, aspartate aminotransferase, albumin, cholinesterase, creatinine, direct bilirubin, gamma-glutamyl transpeptidase, total bilirubin, total bile acid and total protein showed a decrease during the whole gestational period, while alkaline phosphatase and uric acid increased. Urea nitrogen, β2-microglobulin and cystatin-C fell significantly during the first trimester and then remained relatively stable until third trimester. Reference intervals of all the measurands during normal pregnancy have been established.

Conclusions

The reference intervals established here can be adopted in other clinical laboratories after appropriate validation. We verified the importance, for some measurands, of partitioning by gestational age when establishing reference intervals during pregnancy.

Assessment of liver function in pregnant anemic women upon oral iron and folic acid supplementation

Oral iron therapy is the most widely prescribed treatment for iron deficiency anemia. However, oral iron supplementation may also lead to various health problems. The recognition of these physiological variations is essential for the diagnosis of liver diseases during the course of pregnancy. Therefore, the objective of this study was to assess the variations in levels of routine liver function tests (LFTs) in pregnant women before and after iron and folic acid treatment. Iron and folic acid was supplemented to 500 normal pregnant anemic women (mild=200, moderate=200 and severe=100) and 100 age matched normal pregnant non-anemic as controls daily for 100 days. Blood index values and liver function parameters were precisely monitored. Hemoglobin (Hb), total protein (TP), iron (Fe), albumin and alkaline phosphatase (ALP) levels were found increased (P<0.001; P<0.01; P<0.05) after treatment in mild, moderate, severe and control, respectively. Lipid peroxidation (LPx), aspartate transaminase (AST) and alanine transaminase (ALT) were increased in pretreated mild, moderate and severe groups and further increased after all treated subjects. Moreover, gamma-glutamyl transpeptidase (GGT) was found to decrease in pre and posttreated subjects. Treatment with iron and folic acid although has remarkable efficacy for Hb and body iron stores although for the cost of increasing the associated compartment of total bilirubin, AST and ALT concomitant with decreased GGT levels. Data obtained from the present study provide new insights into the mandatory application of liver function tests likely to be monitored at regular and specific intervals during the course of pregnancy.

Liver disease in pregnancy

Changes in the liver biochemical profile are normal in pregnancy. However, up to 3% to 5% of all pregnancies are complicated by liver dysfunction. It is important that liver disease during pregnancy is recognized because early diagnosis may improve maternal and fetal outcomes, with resultant decreased morbidity and mortality. Liver diseases that occur in pregnancy can be divided into 3 different groups: liver diseases that are unique to pregnancy, liver diseases that are not unique to pregnancy but can be revealed or exacerbated by pregnancy, and liver diseases that are unrelated to but occur coincidentally during pregnancy.

Liver disease in pregnancy

This article briefly discusses gestational physiologic changes and thereafter reviews liver diseases during pregnancy, which are divided into 3 main categories. The first category includes conditions that are unique to pregnancy and generally resolve with the termination of pregnancy, the second category includes liver diseases that are not unique to the pregnant population but occur commonly or are severely affected by pregnancy, and the third category includes diseases that occur coincidentally with pregnancy and in patients with underlying chronic liver disease, with cirrhosis, or after liver transplant who become pregnant.

Fetal gender affects maternal serum total and placental alkaline phosphatase levels during pregnancy

OBJECTIVE

To analyze whether fetal gender affects total alkaline phosphatase (ALP) and placental ALP levels in normal pregnancy, and to determine the gestational age at which the difference occurs.

METHODS

In this longitudinal study, serum total and placental ALP measurements were carried out in 30 normal pregnant women during different ranges of gestational weeks. Infant sex was recorded at the delivery for all women included in the study. Total and placental ALP levels were compared between pregnant women bearing female and male fetuses.

RESULTS

At all gestational weeks studied, both total and placental ALP levels were higher in pregnant women carrying female fetuses than in male bearing pregnant women. Particularly, both total (260.9+/-110.2 versus 239.9+/-102.3; p=0.03) and placental (73.1+/-22.4 versus 61+/-18.2; p=0.04) ALP levels were significantly higher in the female group than in the male between 24 and 28 weeks, and the significant difference persisted between 32 and 36 weeks (p=0.02).

CONCLUSIONS

Fetal gender seems to affect total and placental ALP levels in healthy pregnant women, particularly during the second and third trimester of pregnancy. Higher ALP levels in pregnant women with female fetuses than in those with male fetuses may suggest that knowledge of the fetal gender may be in particular importance for the studies using ALP as a marker for the prediction of variety of diseases and complications seen during pregnancy.

Liver disease in pregnancy

Liver dysfunction during pregnancy can be caused by conditions that are specific to pregnancy or by liver diseases that are not related to pregnancy itself. This review attempts to summarize the epidemiology, pathophysiology, and management of the different pregnancy-related liver diseases, and to review different liver diseases not related to pregnancy and how they may affect or be effected by pregnancy. Some of the liver diseases specific to pregnancy can cause significant morbidity and mortality both to the mother and to the fetus, while most of the liver diseases not specific to pregnancy do not have a deleterious effect on the pregnancy itself.

Effect of parity on bone mineral density in female rhesus macaques from Cayo Santiago

This cross-sectional study investigates the relationship between parity, bone mineral density, and spontaneous osteopenia/osteoporosis in a large skeletal population of female rhesus macaques (Macaca mulatta) from the free-ranging colony of Cayo Santiago, Puerto Rico. The sample consists of 119 mature female monkeys aged 4.0-22.2 years at time of death. The data consist of measurements of bone mineral content (BMC) and bone mineral density (BMD), obtained from dual-energy X-ray absorptiometry (DEXA) of the last lumbar vertebra. After controlling for age, there is a significant increase in BMD of the spine with increasing parity (P = 0.0006), up to a parity of 7 offspring. Thus, high parity initially has a positive effect on BMD in female rhesus monkeys, but this positive effect disappears with parities that are greater than 7 offspring. After controlling for parity, however, age has a negative (P = 0.015) effect on BMD, beginning several years after the attainment of peak BMD (age 9.5 years). Thus, it appears that parity initially mitigates the effects of aging, but the positive effect of parity on BMD is eventually overwhelmed by the aging process. Mean BMC and BMD values are higher in parous females compared to nulliparous females in the same age range. Similarly, females with low parity have significantly lower mean BMD values than do age-matched high-parity controls, and the frequency of osteopenia and osteoporosis is greater in low-parity females. Forty-three percent (43%) of the osteopenic/osteoporotic females in the sample are members of the low-parity group, even though it composes only 13% (16/119) of the entire sample. This study demonstrates that the free-ranging female rhesus monkeys from Cayo Santiago are a good nonhuman primate model for the study of bone mineral density, parity, osteopenia, and osteoporosis.

Placental alkaline phosphatase, insulin, and adenine nucleotides or adenosine synergistically promote long-term survival of serum-starved mouse embryo and human fetus fibroblasts

Earlier we showed that in serum-starved fibroblasts placental alkaline phosphatase (PALP) can exert growth factor-like effects. Here we report that in mouse embryo (NIH 3T3) and human fetus (HTB-157) fibroblasts, PALP (200 nM) alone provided full protection against serum starvation-induced cell death for 5 days. After 12 days, substantial effects of PALP on cell survival required the copresence of insulin (500 nM) and ATP or adenosine (100 microM). In serum-starved NIH 3T3 cells, PALP induced activating phosphorylation of p42/p44 mitogen-activated protein (MAP) kinases; insulin, but not ATP, had small additional effects. PALP also stimulated the expression of various cyclins; ATP both prolonged and enhanced PALP-induced expression of cyclins A and E. Finally, ATP/adenosine enhanced activation of Akt kinase by insulin. The results suggest that PALP may be a regulator of growth and remodeling of fetal tissues during the second and third trimester of pregnancy when it is expressed.

Growth factor-like effects of placental alkaline phosphatase in human fetus and mouse embryo fibroblasts

Human placental alkaline phosphatase (PALP) is synthesized in the placenta during pregnancy and is also expressed in many cancer patients; however, its physiological role is unknown. Here we show that in human fetus fibroblasts as well as normal and H-ras-transformed mouse embryo fibroblasts PALP stimulates DNA synthesis and cell proliferation in synergism with insulin, zinc and calcium. The mitogenic effects of PALP are associated with the activation of c-Raf-1, p42/p44 mitogen-activated protein kinases, p70 S6 kinase, Akt/PKB kinase and phosphatidylinositol 3'-kinase. The results suggest that in vivo PALP may promote fetus development as well as the growth of cancer cells which express oncogenic Ras.

Evaluation of abnormal liver function in pregnancy

Liver disease in pregnancy may present in a subtle or dramatic fashion. An approach using the pattern of liver function abnormalities, time of gestation, and constellation of symptoms will narrow the diagnostic possibilities. Diagnostic tests, including serology, ultrasonography of the hepatobiliary tree, and liver biopsy, can make a definitive diagnosis.

Effect of gestational age on levels of serum alkaline phosphatase isoenzymes in healthy pregnant women

OBJECTIVES

To confirm that the bone isoenzyme of alkaline phosphatase (ALP) contributes significantly to the increased ALP in normal pregnancy, and to determine the gestational age at which the increase occurs.

METHODS

Cross-sectional determinations of serum total, bone and placental ALP were carried out in 67 normal pregnant women. The results were compared with those of 18 normal age-matched non-pregnant controls using Student's t-test.

RESULTS

At both 31-32 weeks and 38 weeks of gestation, serum activities of bone ALP were increased significantly (P < 0.05 and P < 0.001, respectively) when compared with controls. The percentage contribution of bone ALP to the total was higher at 31-32 weeks and lower at 38 weeks when compared with the contribution from placental ALP.

CONCLUSION

Knowledge of time of elevation of serum bone ALP activity in normal pregnancy will be helpful in the interpretation of elevated serum total ALP activity during pregnancy.

Quantitation of skeletal alkaline phosphatase isoenzyme activity in canine serum

Pursuing the hypothesis that quantitation of skeletal alkaline phosphatase (ALP) activity in canine serum would provide an index of the rate of bone formation, we compared three methods for isoenzyme-specific identification of skeletal ALP activity in canine serum: heat inactivation, wheat germ agglutinin (WGA) precipitation, and concanavalin A (ConA) precipitation. ALP isoenzyme activities were extracted from canine bone, intestine, and liver, diluted into heat-inactivated canine serum (i.e., serum without ALP activity), and used as calibrators of ALP isoenzyme activities. Differential sensitivity to inhibition by 10 mM L-homoarginine was used to distinguish intestinal ALP activity from hepatic and skeletal ALP activities (i.e., 9, 80, and 72% inhibition, respectively). To allow resolution of skeletal ALP activity from hepatic ALP activity, we tested two established methods (heat inactivation and WGA precipitation) and a novel method, ConA precipitation. The organ-derived skeletal and hepatic ALP isoenzyme activities were used to compare these three methods with respect to linearity, isoenzyme separation, and precision. All three methods were linear, but the WGA and ConA methods afforded greater isoenzyme separation and precision. The relative extent of isoenzyme separation (i.e., the difference in percentage remaining skeletal and hepatic ALP isoenzyme activities) averaged 23, 40, and 47% remaining ALP activity for the heat, WGA, and ConA methods, respectively. However, when these methods were applied to the quantitation of skeletal ALP activity in sera from 10 young and 10 adult beagles, the WGA method was found to be unacceptable because most of the results fell outside the range of the WGA assay calibrators (i.e., greater than 100% skeletal ALP activity). The heat and ConA methods showed that the amount of skeletal ALP activity in the beagle sera decreased with age, both as ALP activity per liter and as percentage of total serum ALP activity (p less than 0.001 for each). Skeletal ALP activity levels determined by ConA were correlated with values determined by heat inactivation (r = 0.87, p less than 0.001) but not with WGA-determined levels (r = 0.26). Intestinal ALP activity was detected in only 1 of these 20 sera. We conclude that ConA precipitation can be used for quantitation of skeletal ALP activity in beagle serum.

Affinity electrophoresis of alkaline phosphatase using polyacrylamide gels

A method is described for the separation of liver and bone isoenzymes of alkaline phosphatase in serum using wheat germ lectin affinity electrophoresis in a polyacrylamide gel matrix. The electrophoretic mobilities of liver and intestinal isoenzyme are essentially not affected by lectin, but the bone enzyme is retarded and separated from the liver fraction. Affinity electrophoresis in polyacrylamide gel, combined with agarose gel electrophoresis, and a solid-phase linked antibody precipitation procedure for intestinal alkaline phosphatase allowed the various isoenzyme fractions, biliary, liver, bone and intestinal, to be quantitated.