Increased birth weight is associated with altered gene expression in neonatal foreskin

Associations of maternal stress, gene expression, and newborn birthweight in the Democratic Republic of Congo

Objectives

Maternal stress has long been associated with lower birthweight, which is associated with adverse health outcomes including many adult diseases. The underlying mechanisms remain elusive although changes in gene expression may play a role. Studies are only beginning to test how maternal stress impacts gene expression as reflected in the transcriptome.

Materials and Methods

In a cohort of mothers and newborns in the eastern Democratic Republic of Congo (n=93), we studied the effects of four maternal stress measures (chronic stress, war trauma, sexual trauma, and general trauma) on the transcriptomes of maternal venous blood, newborn venous blood, and placental tissues, and on newborn birthweight. Maternal stress was investigated as independent measures, principal components, and clusters identified through machine learning. The transcriptome was assayed using the ClariomD chip. Multiple regression models were used to test for associations between maternal stress measures, the transcriptome, and newborn birthweight.

Results

None of the maternal stress measures showed an association with expression of individual genes. In contrast, when testing global gene expression, war trauma was significantly associated with the placental transcriptome. War trauma was also significantly associated with birthweight in multiple models. Mediation analysis indicated that ~14% of the effect of war trauma on birthweight was mediated by a placental gene expression component.

Discussion

Our results suggest that gene expression in the placenta, which represents the interface between mother and developing fetus, may partially mediate the negative impact of maternal stress on newborn birthweight.

PCB126 exposure during pregnancy alters maternal and fetal gene expression

Polychlorinated biphenyls (PCBs) are organic pollutants that can have lasting impacts on offspring health. Here, we sought to examine maternal and fetal gene expression differences of aryl hydrocarbon receptor (AHR)-regulated genes in a mouse model of prenatal PCB126 exposure. Female mice were bred and gavaged with 1 µmole/kg bodyweight PCB126 or vehicle control on embryonic days 0 and 14, and maternal and fetal tissues were collected on embryonic day 18.5. Total RNAs were isolated, and gene expression levels were analyzed in both maternal and fetal tissues using the NanoString nCounter system. Interestingly, we found that the expression levels of cytochrome P450 (Cyp)1a1 and Cyp1b1 were significantly increased in response to PCB exposure in the tested maternal and fetal tissues. Furthermore, PCB exposure altered the expression of several other genes related to energy balance, oxidative stress, and epigenetic regulation in a manner that was less consistent across tissue types. These results indicate that maternal PCB126 exposure significantly alters gene expression in both developing fetuses and pregnant dams, and such changes vary in intensity and expressivity depending on tissue type. The altered gene expression may provide insights into pathophysiological mechanisms by which in utero PCB exposures contribute to PCB-induced postnatal metabolic diseases.

Methylation Status of GLP2R, LEP and IRS2 in Small for Gestational Age Children with and without Catch-up Growth

OBJECTIVE

In small for gestational age (SGA) children, catch-up growth could be influenced by methylation of several genes involved in metabolism. Epigenetics may influence the development of metabolic diseases in adulthood. To compare the methylation of leptin (LEP), glucagon-like peptide-2 receptor (GLP2R), insulin receptor substrate-2 (IRS2) in SGA patients with and without catch-up growth.

METHODS

Observational prospective study of SGA children. Demographical and clinical variables were collected from clinical records and parents’ questionnaire. Methylation status of LEP, IRS2, and GLP2R promoters was evaluated in DNA extracted from patient and one parent saliva samples.

RESULTS

Forty-eight SGA patients were included. Twenty-six (54.2%) had catch-up growth phenotype and 22 (45.8%) did not. The median age was 5.2 years [RIC 4.1-6.8] without difference between groups (p=0.306). The catch-up group had increased appetite (42.3% vs 9.1%, p=0.008), family history of dyslipidemia (42.3% vs 27.3%) and diabetes (34.6% vs 22.7%) compared to non-catch-up group. Catch-up patients had significantly larger waist circumference compared to non-catch-up group (median 55 cm [RIC 52-58] versus median 49.5 cm [RIC46-52]; p<0.001). LEP and GLP2R were methylated in all samples. IRS2 was methylated in 60% of SGA patients without difference between groups (p=0.520).

CONCLUSION

There is no association between IRS2 methylation and catch-up growth among SGA patients. LEP and GLP2R were methylated in all SGA patients. Gene methylation may be implicated in metabolic disease later in life. More studies should be performed to confirm this hypothesis.

Placental genomic and epigenomic signatures associated with infant birth weight highlight mechanisms involved in collagen and growth factor signaling

Birth weight (BW) represents an important clinical and toxicological measure, indicative of the overall health of the newborn as well as potential risk for later-in-life outcomes. BW can be influenced by endogenous and exogenous factors and is known to be heavily impacted in utero by the health and function of the placenta. An aspect that remains understudied is the influence of genomic and epigenomic programming within the placenta on infant BW. To address this gap, we set out to test the hypothesis that genes involved in critical placental cell signaling are associated with infant BW, and are likely regulated, in part, through epigenetic mechanisms based on microRNA (miRNA) mediation. This study leveraged a robust dataset based on 390 infants born at low gestational age (ranged 23-27 weeks) to evaluate genome-wide expression profiles of both mRNAs and miRNAs in placenta tissues and relate these to infant BW. A total of 254 mRNAs and 268 miRNAs were identified as associated with BW, the majority of which showed consistent associations across placentas derived from both males and females. BW-associated mRNAs were found to be enriched for important biological pathways, including glycoprotein VI (the major receptor for collagen), human growth, and hepatocyte growth factor signaling, a portion of which were predicted to be regulated by BW-associated miRNAs. These miRNA-regulated pathways highlight key mechanisms potentially linking endogenous/exogenous factors to changes in birth outcomes that may be deleterious to infant and later-in-life health.

Parent-reported birth information: birth weight, birth length and gestational age. Validation study in the SENDO project

OBJECTIVE

To test the validity of parent-reported birth information obtained through an online, self-administered questionnaire.

METHOD

The SENDO project is a prospective and dynamic paediatric cohort of Spanish children aged 4 to 6 years old at recruitment. Objective data from medical birth records were compared to parent-reported data getting intra-class correlation coefficients (ICC) for quantitative variables and weighted Kappa Index for qualitative ones. Percentage of responders and of total agreement was also evaluated.

RESULTS

Parental response rate was over 99% for birth weight and gestational age and 76% for birth length. ICC for birth weight was 0.95 (95% confidence interval [95%CI]: 0.94-0.96) and 0.78 (95%CI: 0.73-0.83) for birth length, both showing very high correlations. The total agreement percentage for gestational age was 97%, and Kappa weighted index was 0.90 (95%CI: 0.89-0.90), showing a very high agreement as well.

CONCLUSIONS

We found high correlations and excellent agreement in parent-reported birth data 4 to 6 years after delivery. Our results show parent-reported birth data, especially birth weight, are valid for use in epidemiological research.

In utero sFlt-1 exposure differentially affects gene expression patterns in fetal liver

The soluble fms-like tyrosine kinase factor 1 (sFlt-1) is a major contributor to antiangiogenesis during preeclampsia. However, little is known about the effects of sFlt-1 on fetal health. In this study we aim to evaluate the effects of the sFlt-1 concentration during pregnancy on fetal liver physiology. We used adenoviral gene delivery in Sprague-Dawley dams (seven females, 10 weeks old) during mid-gestation (gestational day 8) with adenovirus overexpressing sFlt-1, and age-matched controls (six females, 10 weeks old) with empty adenoviral virus in order to quantify the sFlt-1 concentrations in pregnant dams. Dams exposed to adenoviral sFlt-1 delivery were subdivided into a low (n=4) and high sFlt-1 (n=3) group based on host response to the virus. One-way analysis of variance showed that fetuses (five per dam) exposed to high sFlt-1 concentrations in utero show fetal growth restriction (1.84±0.043 g high sFlt-1 v. 2.32±0.036 g control; mean (M)±s.e.m.; P&lt;0.001), without hypertension or proteinuria in the dams. In continuation, the microarray analysis of the fetal liver of the high sFlt-1 group showed significant enrichment of key genes for fatty acid metabolism and Ppara targets. In addition, using pyrosequencing, we found that the Ppara enrichment in the high sFlt-1 group is accompanied by decreased methylation of its promoter (1.89±0.097 mean % methylation in high sFlt-1 v. 2.26±0.095 mean % methylation in control, M±s.e.m., P&lt;0.02). Our data show that high sFlt-1 concentrations during pregnancy have detrimental effects on the fatty acid metabolism genes and the Ppara targets in the fetal liver.

Smoking during pregnancy increases chemerin expression in neonatal tissue

NEW FINDINGS

What is the central question of this study? Is chemerin, an adipokine implicated in obesity, increased in neonates following in utero cigarette smoke exposure. What is the main finding and its importance? Chemerin mRNA expression was increased and chemerin DNA methylation was decreased in babies born to mothers who smoked during pregnancy. These data provide a potential mechanism that may be mediating the increased obesity risk in individuals that are born to mothers who smoked during pregnancy.

ABSTRACT

It has been shown that in utero tobacco exposure increases offspring risk for obesity, but the mechanisms responsible for this increased risk are not well understood. Chemerin is an adipokine that regulates adipocyte differentiation. This chemokine is elevated in obese individuals and with smoke exposure, but its levels have not been measured in neonates exposed to cigarette smoke in utero. We examined chemerin gene expression [n = 31 non-smoker (NS) and 15 smoker (S)] and DNA methylation (n = 28 NS and n = 11 S) in skin collected from babies born to mothers who smoked during pregnancy as compared to non-smoking controls. Quality RNA and DNA were isolated from foreskin tissue following circumcision, and chemerin gene expression and DNA methylation were assessed. Further, in a second cohort, we utilized primary dermal foreskin fibroblasts as a functional measure of adipogenesis in living cells (n = 11 NS and n = 8 S). Cells were stimulated with an adipogenic cocktail, mRNA was isolated from cells after 14 days, and chemerin gene expression assessed via real-time PCR. Chemerin mRNA was elevated in both whole tissue (NS: 2409.20 ± 555.28 counts and S: 2966.72 ± 636.84 counts; P < 0.01) and primary fibroblasts (NS: 1.12 ± <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>0.55</mml:mn> <mml:mspace/> <mml:msup><mml:mn>2</mml:mn> <mml:mrow><mml:mi>Δ</mml:mi> <mml:mi>Δ</mml:mi> <mml:msub><mml:mi>C</mml:mi> <mml:mi>T</mml:mi></mml:msub> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> and S: 2.13 ± <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>1.34</mml:mn> <mml:mspace/> <mml:msup><mml:mn>2</mml:mn> <mml:mrow><mml:mi>Δ</mml:mi> <mml:mi>Δ</mml:mi> <mml:msub><mml:mi>C</mml:mi> <mml:mi>T</mml:mi></mml:msub> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> ; P = 0.04) collected from infants born to smoking mothers. Chemerin DNA methylation was reduced in whole tissue of offspring born to smokers (NS: 4.18 ± 1.28 and S: 3.07 ± 1.31%; P = 0.02), which may contribute to the increased gene expression. Neonates born to mothers who smoke during pregnancy exhibit distinct changes in chemerin gene expression in response to in utero tobacco smoke exposure which are regulated in part by epigenetic alterations.