Dominick J. Lemas

Alterations in human milk leptin and insulin are associated with early changes in the infant intestinal microbiome

BACKGROUND Increased maternal body mass index (BMI) is a robust risk factor for later pediatric obesity. Accumulating evidence suggests that human milk (HM) may attenuate the transfer of obesity from mother to offspring, potentially through its effects on early development of the infant microbiome. OBJECTIVES Our objective was to identify early differences in intestinal microbiota in a cohort of breastfeeding infants born to obese compared with normal-weight (NW) mothers. We also investigated relations between HM hormones (leptin and insulin) and both the taxonomic and functional potentials of the infant microbiome. DESIGN Clinical data and infant stool and fasting HM samples were collected from 18 NW [prepregnancy BMI (in kg/m(2)) <24.0] and 12 obese (prepregnancy BMI >30.0) mothers and their exclusively breastfed infants at 2 wk postpartum. Infant body composition at 2 wk was determined by air-displacement plethysmography. Infant gastrointestinal microbes were estimated by using 16S amplicon and whole-genome sequencing. HM insulin and leptin were determined by ELISA; short-chain fatty acids (SCFAs) were measured in stool samples by using gas chromatography. Power was set at 80%. RESULTS Infants born to obese mothers were exposed to 2-fold higher HM insulin and leptin concentrations (P < 0.01) and showed a significant reduction in the early pioneering bacteria Gammaproteobacteria (P = 0.03) and exhibited a trend for elevated total SCFA content (P < 0.06). Independent of maternal prepregnancy BMI, HM insulin was positively associated with both microbial taxonomic diversity (P = 0.03) and Gammaproteobacteria (e.g., Enterobacteriaceae; P = 0.04) and was negatively associated with Lactobacillales (e.g., Streptococcaceae; P = 0.05). Metagenomic analysis showed that HM leptin and insulin were associated with decreased bacterial proteases, which are implicated in intestinal permeability, and reduced concentrations of pyruvate kinase, a biomarker of pediatric gastrointestinal inflammation. CONCLUSION Our results indicate that, although maternal obesity may adversely affect the early infant intestinal microbiome, HM insulin and leptin are independently associated with beneficial microbial metabolic pathways predicted to increase intestinal barrier function and reduce intestinal inflammation. This trial was registered at clinicaltrials.gov as NCT01693406.

Early infant adipose deposition is positively associated with the n-6 to n-3 fatty acid ratio in human milk independent of maternal BMI

Background/Objectives:Excessive infant weight gain in the first 6-month of life is a powerful predictor of childhood obesity and related health risks. In mice, omega-6 fatty acids (FAs) serve as potent ligands driving adipogenesis during early development. The ratio of omega-6 relative to omega-3 (n-6/n-3) FA in human milk (HM) has increased threefold over the last 30 years, but the impact of this shift on infant adipose development remains undetermined. This study investigated how maternal obesity and maternal dietary FA (as reflected in maternal red blood cells (RBCs) composition) influenced HM n-6 and n-3 FAs, and whether the HM n-6/n-3 ratio was associated with changes in infant adipose deposition between 2 weeks and 4 months postpartum.Subjects/Methods:Forty-eight infants from normal weight (NW), overweight (OW) and obese (OB) mothers were exclusively or predominantly breastfed over the first 4 months of lactation. Mid-feed HM and maternal RBC were collected at either transitional (2 weeks) or established (4 months) lactation, along with infant body composition assessed using air-displacement plethysmography. The FA composition of HM and maternal RBC was measured quantitatively by lipid mass spectrometry.Results:In transitional and established HM, docosahexaenoic acid (DHA) was lower (P=0.008; 0.005) and the arachidonic acid (AA)/DHA+eicosapentaenoic acid (EPA) ratio was higher (P=0.05; 0.02) in the OB relative to the NW group. Maternal prepregnancy body mass index (BMI) and AA/DHA+EPA ratios in transitional and established HM were moderately correlated (P=0.018; 0.001). Total infant fat mass was increased in the upper AA/DHA+EPA tertile of established HM relative to the lower tertile (P=0.019). The amount of changes in infant fat mass and percentage of body fat were predicted by AA/EPA+DHA ratios in established HM (P=0.038; 0.010).Conclusions:Perinatal infant exposures to a high AA/EPA+DHA ratio during the first 4 months of life, which is primarily reflective of maternal dietary FA, may significantly contribute to the way infants accumulate adipose.

Higher Intake of PUFAs Is Associated with Lower Total and Visceral Adiposity and Higher Lean Mass in a Racially Diverse Sample of Children

BACKGROUND Polyunsaturated fatty acids (PUFAs) are associated with protection from obesity-related phenotypes in adults; however, the relation between reported intake of PUFAs with body-composition outcomes in children remains unknown. OBJECTIVE Our objective was to examine how self-reported intakes of PUFAs, including total, n-6 (ω-6), and n-3 (ω-3) PUFAs and ratios of n-6 to n-3 PUFAs and PUFAs to saturated fatty acids (SFAs), are associated with measures of adiposity and lean mass (LM) in children. We hypothesized that higher self-reported intakes of PUFAs and the ratio of PUFAs to SFAs would be positively associated with LM and negatively associated with total adiposity. METHODS Body composition and dietary intake were measured in a racially diverse sample of 311 children (39% European American, 34% African American, and 27% Hispanic American) aged 7-12 y. Body composition and abdominal fat distribution were measured by dual-energy X-ray absorptiometry and computed tomography scans, respectively. Self-reported dietary intakes (including total PUFAs, n-3 PUFAs, n-6 PUFAs, and SFAs) were assessed by using two 24-h recalls. Independent-sample t tests and multiple linear regression analyses were conducted. RESULTS Total PUFA intake was positively associated with LM (P = 0.049) and negatively associated with percentage of body fat (%BF; P = 0.033) and intra-abdominal adipose tissue (IAAT; P = 0.022). A higher ratio of PUFAs to SFAs was associated with higher LM (P = 0.030) and lower %BF (P = 0.028) and IAAT (P = 0.048). Intakes of n-3 and n-6 PUFAs were positively associated with LM (P = 0.017 and P = 0.021, respectively), and the ratio of n-6 to n-3 PUFAs was negatively associated with IAAT (P = 0.014). All results were independent of biological, environmental, and genetic covariates. CONCLUSIONS Our results show that a higher self-reported intake of PUFAs and a higher ratio of PUFAs to SFAs are positively associated with LM and negatively associated with visceral adiposity and %BF in a healthy cohort of racially diverse children aged 7-12 y. This trial was registered at clinicaltrials.gov as NCT00726778.

Associations of maternal weight status prior and during pregnancy with neonatal cardiometabolic markers at birth: the Healthy Start study

Background:Maternal obesity increases adult offspring risk for cardiovascular disease; however, the role of offspring adiposity in mediating this association remains poorly characterized.Objective:To investigate the associations of maternal pre-pregnant body mass index (maternal BMI) and gestational weight gain (GWG) with neonatal cardiometabolic markers independent of fetal growth and neonatal adiposity.Methods:A total of 753 maternal–infant pairs from the Healthy Start study, a large multiethnic pre-birth observational cohort were used. Neonatal cardiometabolic markers included cord blood glucose, insulin, glucose-to-insulin ratio (Glu/Ins), total and high-density lipoprotein cholesterol (HDL-c), triglycerides, free fatty acids and leptin. Maternal BMI was abstracted from medical records or self-reported. GWG was calculated as the difference between the first pre-pregnant weight and the last weight measurement before delivery. Neonatal adiposity (percent fat mass) was measured within 72 h of delivery using whole-body air-displacement plethysmography.Results:In covariate adjusted models, maternal BMI was positively associated with cord blood insulin (P=0.01) and leptin (P<0.001) levels, and inversely associated with cord blood HDL-c (P=0.05) and Glu/Ins (P=0.003). Adjustment for fetal growth or neonatal adiposity attenuated the effect of maternal BMI on neonatal insulin, rendering the association nonsignificant. However, maternal BMI remained associated with higher leptin (P<0.0011), lower HDL-c (P=0.02) and Glu/Ins (P=0.05), independent of neonatal adiposity. GWG was positively associated with neonatal insulin (P=0.02), glucose (P=0.03) and leptin levels (P<0.001) and negatively associated with Glu/Ins (P=0.006). After adjusting for neonatal adiposity, GWG remained associated with higher neonatal glucose (P=0.02) and leptin levels (P=0.02) and lower Glu/Ins (P=0.048).Conclusions:Maternal weight prior and/or during pregnancy is associated with neonatal cardiometabolic makers including leptin, glucose and HDL-c at delivery, independent of neonatal adiposity. Our results suggest that intrauterine exposure to maternal obesity influences metabolic processes beyond fetal growth and fat accretion.

CDKAL1 and HHEX are associated with type-2 diabetes-related traits among Yup’ik people

Genome‐wide association studies (GWAS) have identified single nucleotide polymorphisms (SNPs) associated with type 2 diabetes (T2D), mainly among individuals of European ancestry. In the present study, we examined the frequency of these SNPs and their association with T2D‐related traits in an Alaska Native study population with a historically low prevalence of T2D. We also investigated whether dietary characteristics that may protect against T2D, such as n‐3 polyunsaturated fatty acid (PUFA) intake, modify these associations.

Intrinsic disorder and multiple phosphorylations constrain the evolution of the flightin N-terminal region

Flightin is a myosin binding phosphoprotein that originated in the ancestor to Pancrustacea ~500 MYA. In Drosophila melanogaster, flightin is essential for length determination and flexural rigidity of thick filaments. Here, we show that among 12 Drosophila species, the N-terminal region is characterized by low sequence conservation, low pI, a cluster of phosphorylation sites, and a high propensity to intrinsic disorder (ID) that is augmented by phosphorylation. Using mass spectrometry, we identified eight phosphorylation sites within a 29 amino acid segment in the N-terminal region of D. melanogaster flightin. We show that phosphorylation of D. melanogaster flightin is modulated during flight and, through a comparative analysis to orthologs from other Drosophila species, we found phosphorylation sites that remain invariant, sites that retain the charge character, and sites that are clade-specific. While the number of predicted phosphorylation sites differs across species, we uncovered a conserved pattern that relates the number of phosphorylation sites to pI and ID. Extending the analysis to orthologs of other insects, we found additional conserved features in flightin despite the near absence of sequence identity. Collectively, our results demonstrate that structural constraints demarcate the evolution of the highly variable N-terminal region.

The Neonatal Microbiome and Its Partial Role in Mediating the Association between Birth by Cesarean Section and Adverse Pediatric Outcomes

Background: Cesarean sections (CS) are among the most commonly performed surgical procedures in the world. Epidemiologic data has associated delivery by CS with an increased risk of certain adverse health outcomes in children, such as asthma and obesity. Objective: To explore what is known about the effect of mode of delivery on the development of the infant microbiome and discuss the potentially mediating role of CS-related microbial dysbiosis in the development of adverse pediatric health outcomes. Recommendations for future inquiry are also provided. Methods: This study provides a narrative overview of the literature synthesizing the findings of literature retrieved from searches of PubMed and other computerized databases and authoritative texts. Results: Emerging evidence suggests that mode of delivery is involved in the development of the neonatal microbiome and may partially explain pediatric health outcomes associated with birth by CS. Specifically, the gut microbiome of vaginally delivered infants more closely resembles their mothers’ vaginal microbiome and thus more commonly consists of potentially beneficial microbiota such as Lactobacillus, Bifidobacterium, and Bacteroides. Conversely, the microbiome of infants born via CS shows an increased prevalence of either skin flora or potentially pathogenic microbial communities such as Klebsiella, Enterococcus, and Clostridium. Conclusions: Mode of delivery plays an important role in the development of the postnatal microbiome but likely tells only part of the story. More comprehensive investigations into all the pre- and perinatal factors that have the potential to contribute to the neonatal microbiome are warranted.

Linkage and association analysis of circulating vitamin D and parathyroid hormone identifies novel loci in Alaska Native Yup’ik people

BackgroundVitamin D deficiency is a well-documented public health issue with both genetic and environmental determinants. Populations living at far northern latitudes are vulnerable to vitamin D deficiency and its health sequelae, although consumption of traditional native dietary pattern rich in fish and marine mammals may buffer the effects of reduced sunlight exposure. To date, few studies have investigated the genetics of vitamin D metabolism in circumpolar populations or considered genediet interactions with fish and n-3 fatty acid intake.MethodsWe searched for genomic regions exhibiting linkage and association with circulating levels of vitamin D and parathyroid hormone (PTH) in 982 Yup’ik individuals from the Center for Alaska Native Health Research Study. We also investigated potential interactions between genetic variants and a biomarker of traditional dietary intake, the δ15N value.ResultsWe identified several novel regions linked with circulating vitamin D and PTH as well as replicated a previous linkage finding on 2p16.2 for vitamin D. Bioinformatic analysis revealed multiple candidate genes for both PTH and vitamin D, including CUBN, MGAT3, and NFKBIA. Targeted association analysis identified NEBL as a candidate gene for vitamin D and FNDC3B for PTH. We observed significant associations between a variant in MXD1 and vitamin D only when an interaction with the δ15N value was included. Finally, we integrated pathway level information to illustrate the biological validity of the proposed candidate genes.ConclusionWe provide evidence of linkage between several biologically plausible genomic regions and vitamin D metabolism in a circumpolar population. Additionally, these findings suggest that a traditional dietary pattern may modulate genetic effects on circulating vitamin D.

Taq1a polymorphism (rs1800497) is associated with obesity-related outcomes and dietary intake in a multi-ethnic sample of children: Taq1a SNPs and paediatric obesity/diet

In adults, the Taq1a polymorphism (rs1800497) near the D2 receptor (DRD2) gene is associated with body mass index and binge eating and is more prevalent among non‐Hispanic Blacks (NHB) and Hispanic–Americans (HA) relative to non‐Hispanic Whites (NHW). We hypothesize Taq1a polymorphism (rs1800497) risk alleles contribute to paediatric racial/ethnic differences in obesity phenotypes.

The gut microbiota in infants of obese mothers increases inflammation and susceptibility to NAFLD

Maternal obesity is associated with increased risk for offspring obesity and non-alcoholic fatty liver disease (NAFLD), but the causal drivers of this association are unclear. Early colonization of the infant gut by microbes plays a critical role in establishing immunity and metabolic function. Here, we compare germ-free mice colonized with stool microbes (MB) from 2-week-old infants born to obese (Inf-ObMB) or normal-weight (Inf-NWMB) mothers. Inf-ObMB-colonized mice demonstrate increased hepatic gene expression for endoplasmic reticulum stress and innate immunity together with histological signs of periportal inflammation, a histological pattern more commonly reported in pediatric cases of NAFLD. Inf-ObMB mice show increased intestinal permeability, reduced macrophage phagocytosis, and dampened cytokine production suggestive of impaired macrophage function. Furthermore, exposure to a Western-style diet in Inf-ObMB mice promotes excess weight gain and accelerates NAFLD. Overall, these results provide functional evidence supporting a causative role of maternal obesity-associated infant dysbiosis in childhood obesity and NAFLD.Infants born to obese mothers have altered microbiome and increased risk of obesity and NAFLD. Here the authors establish causality by showing that maternal obesity-shaped infant gut microbiome induces macrophage dysfunction, inflammation, and diet-induced metabolic disease in germ-free mice.