The effect of preterm birth on adiposity and metabolic pathways and the implications for later life

Role of Transcription Factors in the Management of Preterm Birth: Impact on Future Treatment Strategies

Preterm birth is defined as the birth of a neonate before 37 weeks of gestation and is considered as a leading cause of the under five deaths of neonates. Neonates born preterm are known to have higher perinatal mortality and morbidity with associated risks of low birth weight, respiratory distress syndrome, gastrointestinal, immunologic, central nervous system, hearing, and vision problems, cerebral palsy, and delayed development. India leads the list of countries with the greatest number of preterm births. The studies focusing on the molecular mechanisms related to the etiology of preterm birth have described the role of different transcription factors. With respect to this, transcription factors like peroxisome proliferator activated receptors (PPAR), nuclear factor kappa β (NF-kβ), nuclear erythroid 2-related factor 2 (Nrf2), and progesterone receptor (PR) are known to be associated with preterm labor. All these transcription factors are linked together with a common cascade involving inflammatory processes. Thus, the current review describes the possible cross-talk between these transcription factors and their therapeutic potential to prevent or manage preterm labor.

Preterm birth and metabolic implications on later life: A narrative review focused on body composition

Preterm newborn infants are characterized by low body weight and lower fat mass at birth compared with full-term newborn neonates. Conversely, at term corrected age, body fat mass is more represented in preterm newborn infants, causing a predisposition to developing metabolic syndrome and cardiovascular diseases in later life with a different risk profile in men as compared with women. Postnatal growth is a complex change in anthropometric parameters and body composition. Both quantity and quality of growth are regulated by several factors such as fetal programming, early nutrition, and gut microbiota. Weight gain alone is not an optimal indicator of nutritional status as it does not accurately describe weight quality. The analysis of body composition represents a potentially useful tool to predict later metabolic and cardiovascular risk as it detects the quality of growth by differentiating between fat and lean mass. Longitudinal follow-up of preterm newborn infants could take advantage of body composition analysis in order to identify high-risk patients who apply early preventive strategies. This narrative review aimed to examine the state-of-the-art body composition among born preterm children, with a focus on those in the pre-school age group.

Sex-Specific Effects of Nutritional Supplements for Infants Born Early or Small: An Individual Participant Data Meta-Analysis (ESSENCE IPD-MA) I-Cognitive Function and Metabolic Risk

Neonatal nutritional supplements are widely used to improve growth and development but may increase risk of later metabolic disease, and effects may differ by sex. We assessed effects of supplements on later development and metabolism. We searched databases and clinical trials registers up to April 2019. Participant-level data from randomised trials were included if the intention was to increase macronutrient intake to improve growth or development of infants born preterm or small-for-gestational-age. Co-primary outcomes were cognitive impairment and metabolic risk. Supplementation did not alter cognitive impairment in toddlers (13 trials, n = 1410; adjusted relative risk (aRR) 0.88 [95% CI 0.68, 1.13]; p = 0.31) or older ages, nor alter metabolic risk beyond 3 years (5 trials, n = 438; aRR 0.94 [0.76, 1.17]; p = 0.59). However, supplementation reduced motor impairment in toddlers (13 trials, n = 1406; aRR 0.76 [0.60, 0.97]; p = 0.03), and improved motor scores overall (13 trials, n = 1406; adjusted mean difference 1.57 [0.14, 2.99]; p = 0.03) and in girls not boys (p = 0.03 for interaction). Supplementation lowered triglyceride concentrations but did not affect other metabolic outcomes (high-density and low-density lipoproteins, cholesterol, fasting glucose, blood pressure, body mass index). Macronutrient supplementation for infants born small may not alter later cognitive function or metabolic risk, but may improve early motor function, especially for girls.

Expression of specific signaling components related to muscle protein turnover and of branched-chain amino acid catabolic enzymes in muscle and adipose tissue of preterm and term calves

Postnatal metabolism depends on maturation of key metabolic pathways around birth. In this regard, endogenous glucose production is impaired in calves born preterm. Concerning protein metabolism, the rates of protein turnover are greater during the neonatal period than at any other period of postnatal life. The mammalian target of rapamycin (mTOR) and the ubiquitin-proteasome system (UPS) are considered as the major regulators of cellular protein turnover. The objectives of this study were to investigate (1) the changes in plasma AA profiles, (2) the mRNA abundance of mTOR signaling and UPS-related genes in skeletal muscle, and (3) the mRNA abundance of branched-chain AA (BCAA) catabolic enzymes in skeletal muscle and adipose tissue in neonatal calves with different degree of maturation during the transition to extrauterine life. Calves (n = 7/treatment) were born either preterm (PT; delivered by cesarean section 9 d before term) or at term (T; spontaneous vaginal delivery) and were left unfed for 1 d. Calves in treatment TC were also spontaneously born but were fed colostrum and transition milk for 4 d. Blood samples were collected from all calves at birth and at 24 h of life. Additional blood samples were taken 2 h after feeding (26 h of life) for PT and T calves, and on d 4 of life for TC, to determine plasma glucose, urea, and AA. Tissue samples from 3 muscles [M. longissimus dorsi (MLD), M. semitendinosus (MST), and M. masseter (MM)], and kidney fat were collected following euthanasia at 26 h after birth (PT, T) or on d 4 of life (TC) at 2 h after feeding. The concentrations of the majority of plasma AA (Ala, Gln, Asn, Cit, Lys, Orn, Thr, and Tyr), nonessential AA, and total AA were greater during the first 24 h and also before and 2 h after feeding in PT than in T. The ratio of plasma BCAA to the aromatic AA (Tyr and Phe) was greatest in TC, followed by T, and least in PT. The mRNA abundance of mTOR and ribosomal protein S6 kinase 1 (S6K1) in MLD and MM was greater in PT and T than in TC. The mRNA abundance of muscle-specific ligases FBXO32 (F-box only protein 32) in the 3 different skeletal muscles and TRIM63 (tripartite motif containing 63) in MLD was greater in PT and T than in TC; in MM, TRIM63 mRNA was greatest in PT. The mRNA for BCKDHA and BCKDHB (the α and β polypeptide of branched-chain α-keto acid dehydrogenase) in kidney fat was elevated in PT and T compared with TC, suggesting a possible enhancement of BCAA oxidation as energy source to cover the energetic and nutritional postnatal demands in PT and T in a starved state. The increased abundances of mTOR-associated signaling factors and muscle-specific ligase mRNA indicate a greater rate of protein turnover in muscles of PT and T in a starved state. Elevated plasma concentrations of several AA may result from enhanced muscle proteolysis and impaired conversion to glucose in the liver of PT calves.

Metabolic profiling of pre-gestational and gestational diabetes mellitus identifies novel predictors of pre-term delivery

Background

Pregnant women with gestational diabetes mellitus (GDM) or type 2 diabetes mellitus (T2DM) are at increased risks of pre-term labor, hypertension and preeclampsia. In this study, metabolic profiling of blood samples collected from GDM, T2DM and control pregnant women was undertaken to identify potential diagnostic biomarkers in GDM/T2DM and compared to pregnancy outcome.

Methods

Sixty-seven pregnant women (21 controls, 32 GDM, 14 T2DM) in their second trimester underwent targeted metabolomics of plasma samples using tandem mass spectrometry with the Biocrates MxP^® Quant 500 Kit. Linear regression models were used to identify the metabolic signature of GDM and T2DM, followed by generalized linear model (GLMNET) and Receiver Operating Characteristic (ROC) analysis to determine best predictors of GDM, T2DM and pre-term labor.

Results

The gestational age at delivery was 2 weeks earlier in T2DM compared to GDM and controls and correlated negatively with maternal HbA1C and systolic blood pressure and positively with serum albumin. Linear regression models revealed elevated glutamate and branched chain amino acids in GDM + T2DM group compared to controls. Regression models also revealed association of lower levels of triacylglycerols and diacylglycerols containing oleic and linoleic fatty acids with pre-term delivery. A generalized linear model ROC analyses revealed that that glutamate is the best predictors of GDM compared to controls (area under curve; AUC = 0.81). The model also revealed that phosphatidylcholine diacyl C40:2, arachidonic acid, glycochenodeoxycholic acid, and phosphatidylcholine acyl-alkyl C34:3 are the best predictors of GDM + T2DM compared to controls (AUC = 0.90). The model also revealed that the triacylglycerols C17:2/36:4 and C18:1/34:1 are the best predictors of pre-term delivery (≤ 37 weeks) (AUC = 0.84).

Conclusions

This study highlights the metabolite alterations in women in their second trimester with diabetes mellitus and identifies predictive indicators of pre-term delivery. Future studies to confirm these associations in other cohorts and investigate their functional relevance and potential utilization for targeted therapies are warranted.

Epigenome Wide Association and Stochastic Epigenetic Mutation Analysis on Cord Blood of Preterm Birth

Preterm birth (PTB) can be defined as the endpoint of a complex process that could be influenced by maternal and environmental factors. Epigenetics recently emerged as an interesting field of investigation since it represents an important mechanism of regulation. This study evaluates epigenetic impact of preterm birth on DNA methylation. Genome-wide DNAm was measured using the Illumina 450K array in cord blood samples obtained from 72 full term and 18 preterm newborns. Lymphocyte composition was calculated based on specific epigenetic markers that are present on the 450k array. Differential methylation analysis was performed both at site and region level; moreover, stochastic epigenetic mutations (SEMs) were also evaluated. The study showed significant differences in blood cell composition between the two groups. Moreover, after multiple testing correction, statistically significant differences in DNA methylation levels emerged between the two groups both at site and region levels. Results obtained were compared to those reported by previous EWAS, leading to a list of more consistent genes associated with PTB. Finally, the SEMs analysis revealed that the burden of SEMs resulted significantly higher in the preterm group. In conclusion, PTB resulted associated to specific epigenetic signatures that involve immune system. Moreover, SEMs analysis revealed an increased epigenetic drift at birth in the preterm group.

Influence of early-life risk factors on socioeconomic inequalities in weight gain

Background

Previous research has examined the role of early-life risk factors on childhood weight gain.The extent to which these factors drive socioeconomic differences in weight is unclear. We aimed to quantify the influence of early-life risk factors on the development of socioeconomic inequalities in children's body mass index (BMI) z-score at 10-11 years.

Methods

Overall, 2186 children from the Longitudinal Study of Australian Children were examined. Socioeconomic position (SEP) was measured as a continuous composite of parent's education, occupation and income. The Product of Coefficients mediation method was used to quantify the contribution of maternal smoking during pregnancy, gestational diabetes, prematurity, caesarean section, birthweight, not being breastfed, early introduction of solid food, maternal BMI and paternal BMI to the relationship between SEP and BMI z-score.

Results

Each increasing decile of SEP (higher SEP) was associated with a 0.05 unit lower (95% CI: -0.06, -0.03) BMI z-score at 10-11 years. In total, 83.5% of these differences in BMI z-score could be explained by socioeconomic differences in maternal smoking during pregnancy (26.9%), maternal BMI (39.6%) and paternal BMI (17.0%).

Conclusions

Interventions to reduce socioeconomic inequalities in excess weight gain during childhood should support the attainment of a healthy parental weight and prevent smoking during pregnancy.

Does the association between early life growth and later obesity differ by race/ethnicity or socioeconomic status? A systematic review

PURPOSE

Rapid growth during infancy predicts higher risk of obesity later in childhood. The association between patterns of early life growth and later obesity may differ by race/ethnicity or socioeconomic status (SES), but prior evidence syntheses do not consider vulnerable subpopulations.

METHODS

We systemically reviewed published studies that explored patterns of early life growth (0-24 months of age) as predictors of later obesity (>24 months) that were either conducted in racial/ethnic minority or low-SES study populations or assessed effect modification of this association by race/ethnicity or SES. Literature searches were conducted in PubMed and SocINDEX.

RESULTS

Ten studies met the inclusion criteria. Faster growth during the first 2 years of life was consistently associated with later obesity irrespective of definition and timing of exposure and outcome measures. Associations were strongest in populations composed of greater proportions of racial/ethnic minority and/or low-SES children. For example, ORs ranged from 1.17 (95% CI: 1.11, 1.24) in a heterogeneous population to 9.24 (95% CI: 3.73, 22.9) in an entirely low-SES nonwhite population.

CONCLUSIONS

The impact of rapid growth in infancy on later obesity may differ by social stratification factors such as race/ethnicity and family income. More robust and inclusive studies examining these associations are needed.

Review: Eicosanoids in preterm labor and delivery: Potential roles of exosomes in eicosanoid functions

Preterm delivery is a major obstetric health problem contributing to poor neonatal outcome including low birth weight, respiratory distress syndrome, gastrointestinal, immunologic, central nervous system, hearing, and vision problems. Worldwide, approximately 15 million babies are born prematurely each year. The critical question which remains is how to identify women destined to deliver preterm from those who will achieve a term delivery. Prostaglandins, in all mammals, are important in the parturient process. Increased intrauterine prostaglandin production is associated with labor and in fact prostaglandin E₂ (PGE₂) or analogs are widely used clinically for cervical ripening and labor induction. Measurements of circulating eicosanoids have been problematic because of the rapid and major clearance by the lungs and then kidneys resulting in very low concentrations in plasma. Moreover, since eicosanoids are produced by all mammalian tissues, the sources of the measured eicosanoids are unknown. Our understanding of how cells communicate has undergone a paradigm shift with the recognition of the role of exosomes in intercellular signaling. Recent publications have identified enzymes and products of arachidonic acid metabolism (eicosanoids) within exosomes. This review will explore the potential roles of exosomes in eicosanoid functions that are critical in preterm labor and delivery.

[Low birth weight and obesity: causal or casual association?]

Objective:

To present the conceptual foundations that explain how events occurring during intrauterine life may influence body development, emphasizing the interrelation between low birth weight and risk of obesity throughout life.

Data sources:

Google Scholar, Library Scientific Electronic Online (SciELO), EBSCO, Scopus, and PubMed were the databases. “Catch-up growth”, “life course health”, “disease”, “child”, “development”, “early life”, “perinatal programming”, “epigenetics”, “breastfeeding”, “small baby syndrome”, “phenotype”, “micronutrients”, “maternal nutrition”, “obesity”, and “adolescence” were isolated or associated keywords for locating reviews and epidemiological, intervention and experimental studies published between 1934 and 2014, with complete texts in Portuguese and English. Duplicate articles, editorials and reviews were excluded, as well as approaches of diseases different from obesity.

Data synthesis:

Within 47 selected articles among 538 eligible ones, the thrifty phenotype hypothesis, the epigenetic mechanisms and the development plasticity were identified as fundamental factors to explain the mechanisms involved in health and disease throughout life. They admit the possibility that both cardiometabolic events and obesity originate from intrauterine nutritional deficiency, which, associated with a food supply that is excessive to the metabolic needs of the organism in early life stages, causes endocrine changes. However, there may be phenotypic reprogramming for low birth weight newborns from adequate nutritional supply, thus overcoming a restrictive intrauterine environment. Therefore, catch-up growth may indicate recovery from intrauterine constraint, which is associated with short-term benefits or harms in adulthood.

Conclusions:

Depending on the nutritional adequacy in the first years of life, developmental plasticity may lead to phenotype reprogramming and reduce the risk of obesity.