Normal Birth Weight Men Research Articles

Circulating Metabolomic and Lipidomic Signatures Identify a Type 2 Diabetes Risk Profile in Low-Birth-Weight Men with Non-Alcoholic Fatty Liver Disease

The extent to which increased liver fat content influences differences in circulating metabolites and/or lipids between low-birth-weight (LBW) individuals, at increased risk of type 2 diabetes (T2D), and normal-birth-weight (NBW) controls is unknown. The objective of the study was to perform untargeted serum metabolomics and lipidomics analyses in 26 healthy, non-obese early-middle-aged LBW men, including five men with screen-detected and previously unrecognized non-alcoholic fatty liver disease (NAFLD), compared with 22 age- and BMI-matched NBW men (controls). While four metabolites (out of 65) and fifteen lipids (out of 279) differentiated the 26 LBW men from the 22 NBW controls (p ≤ 0.05), subgroup analyses of the LBW men with and without NAFLD revealed more pronounced differences, with 11 metabolites and 56 lipids differentiating (p ≤ 0.05) the groups. The differences in the LBW men with NAFLD included increased levels of ornithine and tyrosine (PFDR ≤ 0.1), as well as of triglycerides and phosphatidylcholines with shorter carbon-chain lengths and fewer double bonds. Pathway and network analyses demonstrated downregulation of transfer RNA (tRNA) charging, altered urea cycling, insulin resistance, and an increased risk of T2D in the LBW men with NAFLD. Our findings highlight the importance of increased liver fat in the pathogenesis of T2D in LBW individuals.

1355-P: Carbohydrate Overfeeding Unmasks Severe Dysmetabolic Traits in Low-Birth-Weight Men

Background: Low birth weight (LBW) individuals are at increased risk of developing Type 2 diabetes (T2D) , especially when exposed to an affluent dietary pattern. Impaired subcutaneous adipose tissue expandability and ectopic fat storage may represent key features explaining the link between LBW and risk of T2D. We hypothesized that a 4-week simple carbohydrate overfeeding challenge (+25% energy) (COF) would adversely influence dysmetabolic traits including hepatic fat content in LBW compared to normal birth weight (NBW) men. Methods: Twenty-two non-obese LBW and 21 age- and BMI-matched NBW men with a mean age of 37.6 years were included. Body composition, hepatic fat (MR spectroscopy) , glucose and insulin metabolism, hepatic glucose production (HGP; deuterium glucose) , energy metabolism (indirect calorimetry) and selected plasma biomarkers (multiplex ELISA) were measured before and after 4 weeks COF. Results: Fasting plasma glucose and C-peptide levels, as well as energy expenditure (EE) and fat oxidation (FOX) rates increased significantly more in response to COF among the LBW compared to NBW subjects (all P<0.05) . However, despite significantly increased baseline hepatic fat content, COF resulted in similar body weight and hepatic fat content increments in LBW compared to NBW subjects. HGP and hepatic insulin resistance were unaffected by COF in both groups. Fasting plasma adiponectin levels were significantly reduced in LBW versus NBW subjects before and after COF, whereas plasma leptin and FGF21 levels were increased (both P<0.005) after COF in LBW men only. Conclusion: LBW compared to NBW subjects respond to COF with differential increments in plasma glucose, C-peptide, leptin and FGF21 levels, as well as increased EE and FOX rates. The results underscore the importance of LBW individuals avoiding simple carbohydrate overfeeding. Further studies are needed to understand the role of increased hepatic fat and insulin resistance as key mechanisms linking LBW with increased risk of T2D. Disclosure C.Brøns: Stock/Shareholder; Novo Nordisk. A.B.Thuesen: None. L.Justesen: None. L.Elingaard-larsen: None. J.Størling: None. E.R.Danielsen: None. T.Hansen: None. A.A.Vaag: Stock/Shareholder; AstraZeneca. Funding Novo Nordisk Foundation (NNF15OC0016692) , Aase and Ejnar Danielsens Fond, Augustinus Foundation, Simon Spies Fonden, TrygFonden.

Extremely Low Birth Weight and Accelerated Biological Aging.

Extremely low birth weight (ELBW) (<1000 g) survivors are exposed to elevated levels of physiologic stress during their lives and may be susceptible to accelerated aging. Using the oldest known longitudinally followed cohort of ELBW survivors, we compared biological aging in this group using an epigenetic clock to a sample of matched normal birth weight (NBW) (>2500 g) control participants. Buccal cells were collected from 45 ELBW survivors and 49 NBW control participants at 30 to 35 years of age. Epigenetic age was calculated from the weighted average of DNA methylation at 353 cytosine-phosphate-guanine sequence within DNA sites, by using the Illumina Infinium Human Methylation EPIC 850k BeadChip array. Before and after statistically adjusting for neurosensory impairment and the presence of chronic health conditions, a significant sex by birth weight group interaction was observed in the 353-site epigenetic-clock assay (P = .03), whereby ELBW men had a significantly older epigenetic age than NBW men (4.6 years; P = .01). Women born at ELBW were not found to be epigenetically older than their NBW peers. The results of this study suggest that prenatal exposures may play an important role in aging, and that men born preterm may experience accelerated aging relative to their peers. We further highlight the need to monitor and promote the health of preterm survivors, with a particular focus on healthy aging across the life span.

Epigenome- and Transcriptome-wide Changes in Muscle Stem Cells from Low Birth Weight Men

ABSTRACTBackground: Being born with low birth weight (LBW) is a risk factor for muscle insulin resistance and type 2 diabetes (T2D), which may be mediated by epigenetic mechanisms programmed by the intrauterine environment. Epigenetic mechanisms exert their prime effects in developing cells. We hypothesized that muscle insulin resistance in LBW subjects may be due to early differential epigenomic and transcriptomic alterations in their immature muscle progenitor cells.Results: Muscle progenitor cells were obtained from 23 healthy young adult men born at term with LBW, and 15 BMI-matched normal birth weight (NBW) controls. The cells were subsequently cultured and differentiated into myotubes. DNA and RNA were harvested before and after differentiation for genome-wide DNA methylation and RNA expression measurements.After correcting for multiple comparisons (q ≤ 0.05), 56 CpG sites were found to be significantly, differentially methylated in myoblasts from LBW compared with NBW men, of which the top five gene-annotated CpG sites (SKI, ARMCX3, NR5A2, NEUROG, ESRRG) previously have been associated to regulation of cholesterol, fatty acid and glucose metabolism and muscle development or hypertrophy. LBW men displayed markedly decreased myotube gene expression levels of the AMPK-repressing tyrosine kinase gene FYN and the histone deacetylase gene HDAC7. Silencing of FYN and HDAC7 was associated with impaired myotube formation, which for HDAC7 reduced muscle glucose uptake.Conclusions: The data provides evidence of impaired muscle development predisposing LBW individuals to T2D is linked to and potentially caused by distinct DNA methylation and transcriptional changes including down regulation of HDAC7 and FYN in their immature myoblast stem cells.

Fasting unmasks differential fat and muscle transcriptional regulation of metabolic gene sets in low versus normal birth weight men.

BackgroundIndividuals born with low birth weight (LBW) have an increased risk of metabolic diseases when exposed to diets rich in calories and fat but may respond to fasting in a metabolically preferential manner. We hypothesized that impaired foetal growth is associated with differential regulation of gene expression and epigenetics in metabolic tissues in response to fasting in young adulthood.MethodsGenome-wide expression and DNA methylation were analysed in subcutaneous adipose tissue (SAT) and skeletal muscle from LBW and normal birth weight (NBW) men after 36 h fasting and after an isocaloric control study using microarrays.FindingsTranscriptome analyses revealed that expression of genes involved in oxidative phosphorylation (OXPHOS) and other key metabolic pathways were lower in SAT from LBW vs NBW men after the control study, but paradoxically higher in LBW vs NBW men after 36 h fasting. Thus, fasting was associated with downregulated OXPHOS and metabolic gene sets in NBW men only. Likewise, in skeletal muscle only NBW men downregulated OXPHOS genes with fasting. Few epigenetic changes were observed in SAT and muscle between the groups.InterpretationOur results provide insights into the molecular mechanisms in muscle and adipose tissue governing a differential metabolic response in subjects with impaired foetal growth when exposed to fasting in adulthood. The results support the concept of developmental programming of metabolic diseases including type 2 diabetes.FundThe Swedish Research Council, the Danish Council for Strategic Research, the Novo Nordisk foundation, the Swedish Foundation for Strategic Research, The European Foundation for the Study of Diabetes, The EU 6th Framework EXGENESIS grant and Rigshospitalet.

Leukocyte telomere length is associated with elevated plasma glucose and HbA1c in young healthy men independent of birth weight

Telomeres are protein-bound regions of repetitive nucleotide sequences (TTAGGG) at the end of human chromosomes, and their length is a marker of cellular aging. Intrauterine growth restriction is associated with shorter blood cell telomeres at birth and individuals with type 2 diabetes have shorter telomeres. Individuals with a low birth weight (LBW) have an increased risk of metabolic disease and type 2 diabetes. Therefore, we aimed to investigate the relationship between birth weight and telomere length and the association between birth weight, telomere length and cardiometabolic phenotype in adulthood. Young, healthy men with LBW (n = 55) and normal birth weight (NBW) (n = 65) were examined including blood pressure, blood samples and body composition. Leukocyte telomere length was determined using a high-throughput qPCR method. The LBW men were more insulin resistant as determined by the HOMA-IR index. There was no difference in telomere length between LBW and NBW subjects. When adjusting for birth weight and cohort effect, significant negative associations between telomere length and fasting glucose (P = 0.003) and HbA1c (P = 0.0008) were found. In conclusion, no significant difference in telomere length was found between LBW and NBW men. The telomere length was negatively associated with glucose concentrations and HbA1c levels within the normal non-diabetic range independent of birth weight.

Plasma ceramide levels are altered in low and normal birth weight men in response to short-term high-fat overfeeding

Low birth weight (LBW) individuals have an increased risk of developing insulin resistance and type 2 diabetes compared with normal birth weight (NBW) individuals. We hypothesised that LBW individuals exhibit an increased fatty acid flux into lipogenesis in non-adipose tissue with a resulting accumulation of lipotoxic lipids, including ceramides, in the blood. Therefore, we measured fasting plasma levels of 27 ceramides in 18 young, healthy, LBW men and 25 NBW controls after an isocaloric control diet and a 5-day high-fat, high-calorie diet by HPLC-HRMS. LBW men did not show elevated plasma ceramide levels after the control or high-fat, high-calorie diet. An increased fatty acid oxidation rate in these individuals during both diets may limit ceramide synthesis and thereby compensate for a likely increased fatty acid load to non-adipose tissue. Interestingly, LBW and NBW men decreased d18:0–18:1/d18:1–18:0 and d18:1–24:2/d18:2–24:1 levels and increased the d18:0–24:1a level in response to overfeeding. Plasma d18:0–24:1a and total ceramide levels were positively associated with the fasting blood glucose level and endogenous glucose production after the control diet, and the total ceramide level was in addition positively associated with hepatic insulin resistance. Further studies are needed to determine if lipotoxicity contributes to insulin resistance in LBW individuals.

Escitalopram Ameliorates Hypercortisolemia and Insulin Resistance in Low Birth Weight Men With Limbic Brain Alterations.

Low birth weight (LBW; <2500 g) is linked to the development of insulin resistance and limbic-hypothalamic-pituitary-adrenal (LHPA) axis hyperactivity. Our first aim was to study insulin action, LHPA axis function, and limbic brain structures in young, healthy LBW men vs normal birthweight (NBW) controls (part 1). Our second aim was to investigate the effects of escitalopram vs placebo in LBW men in the LHPA axis and insulin sensitivity (part 2). The maximal (Rdmax) and submaximal (Rdsubmax) rates of insulin-stimulated glucose turnover, LHPA axis, and brain morphology were examined in 40 LBW men and 20 matched NBW men using two-stage hyperinsulinemic euglycemic clamp, 24-hour hormone plasma profiles, and magnetic resonance imaging. Subsequently, all LBW subjects underwent randomized and double-blind treatment with escitalopram 20 mg/d or placebo for 3 months followed by a complete reexamination. Changes in Rdmax/Rdsubmax and plasma-free cortisol 24-hour area under the curve. In LBW vs NBW, Rdsubmax and Rdmax were ∼16% (P = 0.01) and ∼12% (P = 0.01) lower, respectively, and 24-hour free cortisol levels were ∼20% higher (P = 0.02), primarily driven by a ∼99% increase at 05:00 am (P < 0.001). Furthermore, these changes were related to structural alterations within left thalamus and ventromedial prefrontal cortex. However, in LBW men, exposure to escitalopram normalized the free cortisol levels and improved the Rdsubmax by ∼24% (P = 0.04) compared with placebo. LBW vs NBW displayed alterations in key brain structures modulating the LHPA axis, elevated free cortisol levels, and insulin resistance. Escitalopram administration ameliorated these defects, suggesting a potential for LHPA axis modulation compounds to improve insulin action in LBW subjects.

Plasma amino acid levels are elevated in young, healthy low birth weight men exposed to short-term high-fat overfeeding.

Low birth weight (LBW) individuals exhibit a disproportionately increased, incomplete fatty acid oxidation and a decreased glucose oxidation, compared with normal birth weight (NBW) individuals, and furthermore have an increased risk of developing insulin resistance and type 2 diabetes. We hypothesized that changes in amino acid metabolism may occur parallel to alterations in fatty acid and glucose oxidation, and could contribute to insulin resistance. Therefore, we measured fasting plasma levels of 15 individual or pools of amino acids in 18 LBW and 25 NBW men after an isocaloric control diet and after a 5‐day high‐fat, high‐calorie diet. We demonstrated that LBW and NBW men increased plasma alanine levels and decreased valine and leucine/isoleucine levels in response to overfeeding. Also, LBW men had higher alanine, proline, methionine, citrulline, and total amino acid levels after overfeeding compared with NBW men. Alanine and total amino acid levels tended to be negatively associated with the insulin‐stimulated glucose uptake after overfeeding. Therefore, the higher amino acid levels in LBW men could be a consequence of their reduction in skeletal muscle insulin sensitivity due to overfeeding with a possible increased skeletal muscle proteolysis and/or could potentially contribute to an impaired insulin sensitivity. Furthermore, the alanine level was negatively associated with the plasma acetylcarnitine level and positively associated with the hepatic glucose production after overfeeding. Thus, the higher alanine level in LBW men could be accompanied by an increased anaplerotic formation of oxaloacetate and thereby an enhanced tricarboxylic acid cycle activity and as well an increased gluconeogenesis.

Plasma acylcarnitine profiling indicates increased fatty acid oxidation relative to tricarboxylic acid cycle capacity in young, healthy low birth weight men.

We hypothesized that an increased, incomplete fatty acid beta‐oxidation in mitochondria could be part of the metabolic events leading to insulin resistance and thereby an increased type 2 diabetes risk in low birth weight (LBW) compared with normal birth weight (NBW) individuals. Therefore, we measured fasting plasma levels of 45 acylcarnitine species in 18 LBW and 25 NBW men after an isocaloric control diet and a 5‐day high‐fat, high‐calorie diet. We demonstrated that LBW men had higher C2 and C4‐OH levels after the control diet compared with NBW men, indicating an increased fatty acid beta‐oxidation relative to the tricarboxylic acid cycle flux. Also, they had higher C6‐DC, C10‐OH/C8‐DC, and total hydroxyl‐/dicarboxyl‐acylcarnitine levels, which may suggest an increased fatty acid omega‐oxidation in the liver. Furthermore, LBW and NBW men decreased several acylcarnitine levels in response to overfeeding, which is likely a result of an upregulation of fatty acid oxidation due to the dietary challenge. Moreover, C10‐OH/C8‐DC and total hydroxyl‐/dicarboxyl‐acylcarnitine levels tended to be negatively associated with the serum insulin level, and the total hydroxyl‐/dicarboxyl‐acylcarnitine level additionally tended to be negatively associated with the hepatic insulin resistance index. This indicates that an increased fatty acid omega‐oxidation could be a compensatory mechanism to prevent an accumulation of lipid species that impair insulin signaling.

Adipose tissue transcriptomics and epigenomics in low birthweight men and controls: role of high-fat overfeeding

Individuals who had a low birthweight (LBW) are at an increased risk of insulin resistance and type 2 diabetes when exposed to high-fat overfeeding (HFO). We studied genome-wide mRNA expression and DNA methylation in subcutaneous adipose tissue (SAT) after 5 days of HFO and after a control diet in 40 young men, of whom 16 had LBW. mRNA expression was analysed using Affymetrix Human Gene 1.0 ST arrays and DNA methylation using Illumina 450K BeadChip arrays. We found differential DNA methylation at 53 sites in SAT from LBW vs normal birthweight (NBW) men (false discovery rate <5%), including sites in the FADS2 and CPLX1 genes previously associated with type 2 diabetes. When we used reference-free cell mixture adjustments to potentially adjust for cell composition, 4,323 sites had differential methylation in LBW vs NBW men. However, no differences in SAT gene expression levels were identified between LBW and NBW men. In the combined group of all 40 participants, 3,276 genes (16.5%) were differentially expressed in SAT after HFO (false discovery rate <5%) and there was no difference between LBW men and controls. The most strongly upregulated genes were ELOVL6, FADS2 and NNAT; in contrast, INSR, IRS2 and the SLC27A2 fatty acid transporter showed decreased expression after HFO. Interestingly, SLC27A2 expression correlated negatively with diabetes- and obesity-related traits in a replication cohort of 142 individuals. DNA methylation at 652 CpG sites (including in CDK5, IGFBP5 and SLC2A4) was altered in SAT after overfeeding in this and in another cohort. Young men who had a LBW exhibit epigenetic alterations in their adipose tissue that potentially influence insulin resistance and risk of type 2 diabetes. Short-term overfeeding influences gene transcription and, to some extent, DNA methylation in adipose tissue; there was no major difference in this response between LBW and control participants.

Disproportionately increased 24-h energy expenditure and fat oxidation in young men with low birth weight during a high-fat overfeeding challenge.

Low birth weight (LBW) associates with increased risk of developing type 2 diabetes. LBW individuals exhibit disproportionately reduced peripheral insulin action and increased fat oxidation after a 5-day high-fat overfeeding (HFO) challenge. Furthermore, LBW men exhibit increased nocturnal fat oxidation during energy balance and low energy expenditure (EE) during fasting. We hypothesized that short-term HFO could further unmask key defects of whole-body energy metabolism in LBW men. Eighteen LBW (2717±268g) and 26 normal birth weight (NBW) (3893±207g) healthy young men were included in a 5-day HFO (60 E% fat, +50% calories) study. The 24-h EE, respiratory quotient and substrate oxidation rates were assessed by indirect calorimetry using respiratory chambers. After adjusting for body composition, the LBW subjects displayed increased nighttime EE (P=0.02) compared with NBW controls during HFO. Nighttime glucose oxidation rate was decreased (P=0.06, adjusted P=0.05), while both adjusted 24-h (P=0.07) and nighttime (P=0.02) fat oxidation rate was elevated in LBW subjects. The relative contribution of fat oxidation to EE was increased in LBW compared with NBW men during the entire 24-h period (P=0.06) and during nighttime (P=0.03). We suggest that disproportionally enhanced fat oxidation in LBW individuals during short-term HFO represents a compensatory response to reduced subcutaneous adipose tissue expandability and storage capacity. The extent to which this mechanism may lead to, or be replaced by insulin resistance, ectopic fat accumulation and/or glucose intolerance during long-term HFO in LBW needs further studies.

Young men with low birthweight exhibit decreased plasticity of genome-wide muscle DNA methylation by high-fat overfeeding

The association between low birthweight (LBW) and risk of developing type 2 diabetes may involve epigenetic mechanisms, with skeletal muscle being a prime target tissue. Differential DNA methylation patterns have been observed in single genes in muscle tissue from type 2 diabetic and LBW individuals, and we recently showed multiple DNA methylation changes during short-term high-fat overfeeding in muscle of healthy people. In a randomised crossover study, we analysed genome-wide DNA promoter methylation in skeletal muscle of 17 young LBW men and 23 matched normal birthweight (NBW) men after a control and a 5 day high-fat overfeeding diet. DNA methylation was measured using Illumina's Infinium BeadArray covering 27,578 CpG sites representing 14,475 different genes. After correction for multiple comparisons, DNA methylation levels were found to be similar in the LBW and NBW groups during the control diet. Whereas widespread DNA methylation changes were observed in the NBW group in response to high-fat overfeeding, only a few methylation changes were seen in the LBW group (χ(2), p < 0.001). Our results indicate lower DNA methylation plasticity in skeletal muscle from LBW vs NBW men, potentially contributing to understanding the link between LBW and increased risk of type 2 diabetes.

Born with low birth weight in rural Southern India: what are the metabolic consequences 20 years later?

Low birth weight (LBW) is common in the Indian population and may represent an important predisposing factor for type 2 diabetes (T2D) and the metabolic syndrome. Intensive metabolic examinations in ethnic LBW Asian Indians have been almost exclusively performed in immigrants living outside India. Therefore, we aimed to study the metabolic impact of being born with LBW in a rural non-migrant Indian population. One hundred and seventeen non-migrant, young healthy men were recruited from a birth cohort in a rural part of south India. The subjects comprised 61 LBW and 56 normal birth weight (NBW) men, with NBW men acting as controls. Subjects underwent a hyperinsulinaemic euglycaemic clamp, i.v. and oral glucose tolerance tests and a dual-energy X-ray absorptiometry scan. The parents' anthropometric status and metabolic parameters were assessed. Men with LBW were shorter (167±6.4 vs 172±6.0 cm, P<0.0001), lighter (51.9±9 vs 55.4±7 kg, P=0.02) and had a reduced lean body mass (42.1±5.4 vs 45.0±4.5 kg, P=0.002) compared with NBW controls. After adjustment for height and weight, the LBW subjects had increased diastolic blood pressure (77±6 vs 75±6 mmHg, P=0.01). Five LBW subjects had impaired glucose tolerance. In vivo insulin secretion and peripheral insulin action were similar in both the groups. Mothers of the LBW subjects were 3 cm shorter than the control mothers. Only subtle features of the metabolic syndrome and changes in body composition among LBW rural Indians were found. Whether other factors such as urbanisation and ageing may unmask more severe metabolic abnormalities may require a long-term follow-up.