Karen Schellong

Hypothalamic proopiomelanocortin promoter methylation becomes altered by early overfeeding: an epigenetic model of obesity and the metabolic syndrome.

Pre‐ and neonatal overfeeding programmes a permanent obesity disposition and accompanying diabetic and cardiovascular disorders, by unknown mechanisms. We proposed that early overfeeding may alter DNA methylation patterns of hypothalamic promoter regions of genes critically involved in the lifelong regulation of food intake and body weight. We induced neonatal overfeeding by rearing Wistar rats in small litters (SL) and thereafter mapped the DNA methylation status of CpG dinucleotides of gene promoters from hypothalamic tissue, using bisulfite sequencing. Neonatal overfeeding led to rapid early weight gain, resulting in a metabolic syndrome phenotype, i.e. obesity, hyperleptinaemia, hyperglycaemia, hyperinsulinaemia, and an increased insulin/glucose ratio. Accompanying, without group difference to controls, the promoter of the main orexigenic neurohormone, neuropeptide Y, was methylated at low levels (i.e. < 5%). In contrast, in SL rats the hypothalamic gene promoter of the main anorexigenic neurohormone, proopiomelanocortin (POMC), showed hypermethylation (P < 0.05) of CpG dinucleotides within the two Sp1‐related binding sequences (Sp1, NF‐κB) which are essential for the mediation of leptin and insulin effects on POMC expression. Consequently, POMC expression lacked upregulation, despite hyperleptinaemia and hyperinsulinaemia. Accordingly, the extent of DNA methylation within Sp1‐related binding sequences was inversely correlated to the quotients of POMC expression/leptin (P= 0.02) and POMC expression/insulin (P < 0.001), indicating functionality of acquired epigenomic alterations. These data for the first time demonstrate a nutritionally acquired alteration of the methylation pattern and, consequently, the regulatory ‘set point’ of a gene promoter that is critical for body weight regulation. Our findings reveal overfeeding as an epigenetic risk factor of obesity programming and consecutive diabetic and cardiovascular disorders and diseases, in terms of the metabolic syndrome.

Birth weight and long-term overweight risk: systematic review and a meta-analysis including 643,902 persons from 66 studies and 26 countries globally.

Background Overweight is among the major challenging health risk factors. It has been claimed that birth weight, being a critical indicator of prenatal developmental conditions, is related to long-term overweight risk. In order to check this important assumption of developmental and preventive medicine, we performed a systematic review and comprehensive meta-analysis. Methods and Findings Relevant studies published up to January 2011 that investigated the relation between birth weight and later risk of overweight were identified through literature searches using MEDLINE and EMBASE. For meta-analysis, 66 studies from 26 countries and five continents were identified to be eligible, including 643,902 persons aged 1 to 75 years. We constructed random-effects and fixed-effects models, performed subgroup-analyses, influence-analyses, assessed heterogeneity and publication bias, performed meta-regression analysis as well as analysis of confounder adjusted data. Meta-regression revealed a linear positive relationship between birth weight and later overweight risk (p<0.001). Low birth weight (<2,500 g) was found to be followed by a decreased risk of overweight (odds ratio (OR) = 0.67; 95% confidence interval (CI) 0.59–0.76). High birth weight (>4,000 g) was associated with increased risk of overweight (OR = 1.66; 95% CI 1.55–1.77). Results did not change significantly by using normal birth weight (2,500–4,000 g) as reference category (OR = 0.73, 95% CI 0.63–0.84, and OR = 1.60, 95% CI 1.45–1.77, respectively). Subgroup- and influence-analyses revealed no indication for bias/confounding. Adjusted estimates indicate a doubling of long-term overweight risk in high as compared to normal birth weight subjects (OR = 1.96, 95% CI 1.43–2.67). Conclusions Findings demonstrate that low birth weight is followed by a decreased long-term risk of overweight, while high birth weight predisposes for later overweight. Preventing in-utero overnutrition, e.g., by avoiding maternal overnutrition, overweight and/or diabetes during pregnancy, might therefore be a promising strategy of genuine overweight prevention, globally.

Early postnatal life as a critical time window for determination of long-term metabolic health

Epidemiological studies demonstrated a clear phenomenological association between low birth weight and increased cardiometabolic risk later in life, very similar to that in high birth weight subjects. Pre- and/or neonatal overfeeding appears to be an etiological clue. In animal studies, irrespective of birth weight neonatal over-nutrition leads to later overweight, impaired glucose tolerance and cardiometabolic alterations. Probably, perinatally acquired alterations of DNA methylation patterns of gene promoters of central nervous regulators of body weight and metabolism play a key role in mediating these relationships. In humans, the long-term impact of neonatal nutrition is conclusively demonstrated by studies on the consequences of breastfeeding vs. formula-feeding. Taken together, the quantity and quality of nutrition during neonatal life plays a critical role, beyond prenatal development, in the long-term programming of health and disease. This opens a variety of opportunities and challenges to primarily prevent chronic diseases, e.g. the metabolic syndrome.

Increase of long-term 'diabesity' risk, hyperphagia, and altered hypothalamic neuropeptide expression in neonatally overnourished 'small-for-gestational-age' (SGA) rats.

Background Epidemiological data have shown long-term health adversity in low birth weight subjects, especially concerning the metabolic syndrome and ‘diabesity’ risk. Alterations in adult food intake have been suggested to be causally involved. Responsible mechanisms remain unclear. Methods and Findings By rearing in normal (NL) vs. small litters (SL), small-for-gestational-age (SGA) rats were neonatally exposed to either normal (SGA-in-NL) or over-feeding (SGA-in-SL), and followed up into late adult age as compared to normally reared appropriate-for-gestational-age control rats (AGA-in-NL). SGA-in-SL rats displayed rapid neonatal weight gain within one week after birth, while SGA-in-NL growth caught up only at juvenile age (day 60), as compared to AGA-in-NL controls. In adulthood, an increase in lipids, leptin, insulin, insulin/glucose-ratio (all p<0.05), and hyperphagia under normal chow as well as high-energy/high-fat diet, modelling modern ‘westernized’ lifestyle, were observed only in SGA-in-SL as compared to both SGA-in-NL and AGA-in-NL rats (p<0.05). Lasercapture microdissection (LMD)-based neuropeptide expression analyses in single neuron pools of the arcuate hypothalamic nucleus (ARC) revealed a significant shift towards down-regulation of the anorexigenic melanocortinergic system (proopiomelanocortin, Pomc) in SGA-in-SL rats (p<0.05). Neuropeptide expression within the orexigenic system (neuropeptide Y (Npy), agouti-related-peptide (Agrp) and galanin (Gal)) was not significantly altered. In essence, the ‘orexigenic index’, proposed here as a neuroendocrine ‘net-indicator’, was increased in SGA-in-SL regarding Npy/Pomc expression (p<0.01), correlated to food intake (p<0.05). Conclusion Adult SGA rats developed increased ‘diabesity’ risk only if exposed to neonatal overfeeding. Hypothalamic malprogramming towards decreased anorexigenic activity was involved into the pathophysiology of this neonatally acquired adverse phenotype. Neonatal overfeeding appears to be a critical long-term risk factor in ‘small-for-gestational-age babies’.

Acquired Alterations of Hypothalamic Gene Expression of Insulin and Leptin Receptors and Glucose Transporters in Prenatally High-Glucose Exposed Three-Week Old Chickens Do Not Coincide with Aberrant Promoter DNA Methylation

Background Prenatal exposures may have a distinct impact for long-term health, one example being exposure to maternal ‘diabesity’ during pregnancy increasing offspring ‘diabesity’ risk. Malprogramming of the central nervous regulation of body weight, food intake and metabolism has been identified as a critical mechanism. While concrete disrupting factors still remain unclear, growing focus on acquired epigenomic alterations have been proposed. Due to the independent development from the mother, the chicken embryo provides a valuable model to distinctively establish causal factors and mechanisms. Aim The aim of this study was to determine the effects of prenatal hyperglycemia on postnatal hypothalamic gene expression and promoter DNA methylation in the chicken. Methods and Findings To temporarily induce high-glucose exposure in chicken embryos, 0.5 ml glucose solution (30 mmol/l) were administered daily via catheter into a vessel of the chorioallantoic egg membrane from days 14 to 17 of incubation. At three weeks of postnatal age, body weight, total body fat, blood glucose, mRNA expression (INSR, LEPR, GLUT1, GLUT3) as well as corresponding promoter DNA methylation were determined in mediobasal hypothalamic brain slices (Nucleus infundibuli hypothalami). Although no significant changes in morphometric and metabolic parameters were detected, strongly decreased mRNA expression occurred in all candidate genes. Surprisingly, however, no relevant alterations were observed in respective promoter methylation. Conclusion Prenatal hyperglycemia induces strong changes in later hypothalamic expression of INSR, LEPR, GLUT1, and GLUT3 mRNA. While the chicken provides an interesting approach for developmental malprogramming, the classical expression regulation via promoter methylation was not observed here. This may be due to alternative/interacting brain mechanisms or the thus far under-explored bird epigenome.

Fetale Programmierung bei intrauteriner Milieustörung – grundlegende Mechanismen am Beispiel der Körpergewichts- und Stoffwechselregulation

Currently, epidemiological and experimental data indicate that exposures during prenatal and perinatal life may have lifelong consequences for the risk of developing obesity and metabolic and cardiovascular diseases. In this context, observations of the offspring of mothers with gestational diabetes as well as studies of children with low birth weight were most influential. This paper illustrates the current knowledge about perinatal programming of obesity and associated diseases and discusses possible etiopathogenic mechanisms, focussing on epidemiological and animal studies of the consequences of exposure to maternal diabetes and pre-/neonatal undernutrition. The resultant far-reaching potential for primary prevention of chronic diseases as well as the paradigmatic character of these hypotheses and observations for the general understanding of health and disease are highlighted.Currently, epidemiological and experimental data indicate that exposures during prenatal and perinatal life may have lifelong consequences for the risk of developing obesity and metabolic and cardiovascular diseases. In this context, observations of the offspring of mothers with gestational diabetes as well as studies of children with low birth weight were most influential. This paper illustrates the current knowledge about perinatal programming of obesity and associated diseases and discusses possible etiopathogenic mechanisms, focussing on epidemiological and animal studies of the consequences of exposure to maternal diabetes and pre-/neonatal undernutrition. The resultant far-reaching potential for primary prevention of chronic diseases as well as the paradigmatic character of these hypotheses and observations for the general understanding of health and disease are highlighted.

Birth Weight and Later Risk of Type 2 Diabetes

According to the ‘small baby syndrome hypothesis’, birth weight is claimed to show an inverse linear relation to later risk of type 2 diabetes. By looking into the literature 14 studies involving a t

Reduced insulin receptor expression and altered DNA methylation in fat tissues and blood of women with GDM and offspring.

Context Altered expression of the insulin receptor (IR) in adipose tissue (AT) could contribute to gestational diabetes mellitus (GDM) etiopathogenesis. Transcriptional regulation via epigenetic mechanisms (e.g., DNA methylation) may play a critical role. However, the human IR promoter DNA methylation patterns and involvement in gene expression are unknown. Objective We evaluated IR mRNA and protein expression accompanied by targeted DNA methylation analyses in AT and blood cells of women with GDM and their offspring. Design Prospective observational study. Setting Academic clinic and research unit. Participants GDM-affected (n = 25) and matched control (n = 30) mother-child dyads. Main Outcome Measures Maternal IR gene and protein expression in paired subcutaneous (SAT) and visceral adipose tissue samples (VAT). DNA methylation levels in IR promoter and intronic regions in maternal AT and blood cells of mother-offspring pairs. Results In SAT and VAT, IR mRNA/protein expressions were significantly reduced in women with GDMs (P < 0.05). The decrease in VAT was more pronounced and independent of maternal body mass index. VAT IR protein levels were inversely associated with key maternal and neonatal anthropometric and metabolic parameters (P < 0.05). DNA methylation patterns were similar across tissues, with significant yet small size alterations between groups in mothers and offspring (P < 0.05). Conclusion Decreased IR levels in AT may be a relevant pathogenic factor in GDM, affecting materno-fetal metabolism. Further investigation of causal factors for IR dysregulation is necessary, especially in VAT. Potential functional and/or clinical roles of altered DNA methylation also should be evaluated.

Nabelschnurblutspende: Relevante Fakten

lungsraten führt. Die Entnahme des Nabelschnurblutes ist für Mutter und Neugeborenes im Gegensatz zu einer Knochenmarkpunktion schmerzlos. Stammzellen aus Nabelschnurblut können vermutlich über Dekaden in Flüssigstickstoff gelagert werden, ohne ihr Potenzial zu verlieren. Im Vergleich zu Knochenmarkspenderregistern scheinen bei den registrierten Transplantaten aus Nabelschnurblut mehr seltene HLA-Typen vorzuliegen, so dass sich dadurch gerade auch für ethnische Minderheiten die Chancen verbessern, ein HLA-identisches bzw. fast identisches Transplantat zu erhalten. Nachteile des Nabelschurblutes sind durch den Entnahmezeitpunkt direkt nach der Geburt des neugeborenen «Spenders» bedingt, dessen Probe anonymisiert gelagert und verwendet wird. Ein späteres nochmaliges Herantreten an den Spender zum Zweck einer weiteren Stammzellgewinnung für eine Boosterung des Empfängers entfällt bei der allogenen Fremdspende. Bestimmte neu aufgetretene genetische Erkrankungen sind in der Neugeborenenphase nicht ersichtlich und sind bei mangelnder Nachbeobachtung des Spenders nicht gänzlich auszuschliessen. Eine ausführliche Evaluation des genetischen Hintergrundes der Familie des Neugeborenen versucht, dieses Risiko einzugrenzen. Ein wesentlicher Nachteil liegt im begrenzten Volumen (50–200 ml) bzw. der Zellzahl (als Minimum 8 ! 10 8 nukleierte Zellen nötig). Diese Variable ist von verschiedenen geburtshilflichen Faktoren, wie Gestationsalter, intrauterine Wachstumsretardierung, Präeklampsie, Kindsgewicht, Kindsgeschlecht und Geburtsmodus, abhängig. Ebenfalls scheint der Abnabelungszeitpunkt für das in der Restnabelschnur und Plazenta verbleibende Restblut wichtig zu sein, wobei eine Frühabnabelung aufgrund einer Nabelschnurblutentnahme nicht statthaft ist, da dies zu einer kindlichen Hypovolämie und Anämie führen kann. Der Abnabelungszeitpunkt sollte nicht verändert werden. Um die mit der Transplantation von sehr geringen Stammzellzahlen verbundenen Probleme zu überwinden, gibt es neuerdings Versuche einer Ex-vivo-Expansion von Stammzellen vor der Transplantation sowie einer Verwendung von mehreren Transplantaten beim gleichen Empfänger als sogenannte Tandem-Transplantate. Man unterscheidet grundsätzlich zwischen allogenen und autologen Nabelschnurblutbanken. In der Schweiz gibt es mittlerweile zwei allogene Nabelschnurblutbanken für unverwandte Die Transplantation hämatopoetischer Stammzellen aus Nabelschnurblut ist inzwischen dank der sehr guten Resultate klinische Routine geworden [1–9] . Das begrenzte Volumen des Restblutes aus Nabelschnur und Plazenta bzw. die darin enthaltene begrenzte Zellzahl stellte in der Vergangenheit ein Problem dar. Die gegenwärtigen Forschungen zielen inzwischen auf die Behebung dieses Nachteiles ab, z.B. durch die Verwendung von mehreren Transplantaten sowie Ex-vivo-Zellexpansion. Autologe Stammzelltransplantationen aus Nabelschnurblut sind im Gegensatz zu allogenen sehr selten indiziert. Eine Anwendung autologer Stammzellen aus Nabelschnurblut für regenerative Zwecke ist bislang experimentell. Das Nabelschnurblut enthält nach der Abnabelung des Neugeborenen eine für Transplantationen bei Kindern und mit gewissen Einschränkungen Erwachsenen genügend hohe Anzahl an hämatopoetischen Stammzellen. Seit der Einführung der Stammzelltransplantationen aus Nabelschnurblut sind mehr als 6000 unverwandte Transplantationen für eine Vielzahl an Indikationen (z.B. Leukämien, Hämoglobinopathien und Immundefekte) durchgeführt worden. Hierbei sind die Überlebensraten mit denen nach Knochenmarktransplantation vergleichbar (je nach Indikation 40–80%), bei verwandter allogener Nabelschnurbluttransplantation liegt die Überlebensrate sogar bei 75–90%. Vorteile des Nabelschnurblutes sind die schnelle Verfügbarkeit eines HLA-typisierten Transplantates, die niedrige Infektionsgefahr, die weniger strikte Notwendigkeit einer HLA-identischen Transplantation und die niedrigere Transplantat-versusWirt-Erkrankungsrate aufgrund der relativen immunologischen Unreife der mittransplantierten Leukozyten. Ausserdem weisen die Stammzellen aus Nabelschnurblut ein relativ hohes Proliferationspotenzial auf, so dass eine niedrigere Zellzahl von 1–2 ! 10 7 nukleierten Zellen pro Kilogramm Körpergewicht zwar zu einer längeren Aplasiephase, jedoch schliesslich zu vergleichbaren Hei-

Inhaltsverzeichnis Vol. 48, 2008

C. Brezinka, Innsbruck C. Buddeberg, Zürich U. Haller, Zürich H. Hepp, München P. Hillemanns, Hannover W. Holzgreve, Basel J.C. Huber, Wien P. Husslein, Wien B. Imthurn, Zürich M. Kiechle, München S. Leodolter, Wien C. Marth, Innsbruck E. Reinold, Wien H. Salzer, Wien H. Schneider, Bern T. Strowitzki, Heidelberg D. Stucki, Fribourg D. Wallwiener, Tübingen R. Winter, Graz R. Zimmermann, Zürich Revue de gynécologie-obstétrique Gynecologic and Obstetric Review