IGF1 molecular anomalies demonstrate its critical role in fetal, postnatal growth and brain development

IGF1 Haploinsufficiency: Phenotype and Response to Growth Hormone Treatment in 9 Patients

INTRODUCTION

The clinical features of bi-allelic IGF1 defects are well established, i.e., severe growth failure and microcephaly, delayed psychomotor development, and sensorineural deafness. However, information on clinical and endocrine consequences of heterozygous IGF1 variants and treatment options is scarce. We aimed at extending the knowledge base of the clinical presentation and growth response to recombinant human growth hormone (rhGH) of patients carrying such variants.

METHODS

Retrospective case series of patients with pathogenic heterozygous IGF1 variants.

RESULTS

Nine patients from six families were included, harbouring five whole or partial gene deletions and one frameshift variant resulting in a premature stop codon (three de novo, one unknown inheritance). In the other two families, variants segregated with short stature. Mean (SD) birth length was -1.9 (1.3) SDS (n = 7), height -3.8 (0.6) SDS, head circumference -2.5 (0.6) SDS, serum IGF-I -1.9 (0.7) SDS, serum IGFBP-3 1.1 (0.4) SDS (n = 7), and GH peak range 5-31 μg/L (n = 4). Five patients showed feeding problems in infancy. Average height increased after 1 and 2 years of rhGH treatment by 0.8 SDS (range 0.3-1.3 SDS) and 1.3 SDS (range 0.5-2.0 SDS), respectively. Adult height in 2 patients was -2.8 and -1.3 SDS, which was, respectively, 1.3 and 2.9 SDS taller than predicted before start of treatment.

CONCLUSION

Haploinsufficiency of IGF1 causes a variable phenotype of prenatal and postnatal growth failure, microcephaly, feeding difficulties, low/low-normal serum IGF-I values in contrast to serum IGFBP-3 in the upper-normal range. Treatment with rhGH increased growth in the first 2 years of treatment, and in 2 patients adult height after treatment was higher than predicted at treatment initiation.

Dexamethasone exposure during pregnancy triggers metabolic syndrome in offspring via epigenetic alteration of IGF1

BACKGROUND

Previous research has reported that prenatal exposure to dexamethasone (PDE) results in organ dysplasia and increased disease susceptibility in offspring. This study aimed to investigate the epigenetic mechanism of metabolic syndrome induced by PDE in offspring.

METHODS

Pregnant Wistar rats were administered dexamethasone, and their offspring's serum and liver tissues were analyzed. The hepatocyte differentiation model was established to unveil the molecular mechanism. Neonatal cord blood samples were collected to validate the phenomenon and mechanism.

RESULTS

The findings demonstrated that PDE leads to insulin resistance and typical metabolic syndrome traits in adult offspring rats, which originated from fetal liver dysplasia. Additionally, PDE reduced serum corticosterone level and inhibited hepatic insulin-like growth factor 1 (IGF1) signaling in fetal rats. It further revealed that liver dysplasia and functional impairment induced by PDE persist after birth, driven by the continuous downregulation of serum corticosterone and hepatic IGF1 signaling. Both in vitro and in vivo experiments confirmed that low endogenous corticosterone reduces the histone 3 lysine 9 acetylation (H3K27ac) level of IGF1 and its expression by blocking glucocorticoid receptor α, special protein 1, and P300 into the nucleus, resulting in hepatocyte differentiation inhibition and liver dysplasia. Intriguingly, neonatal cord blood samples validated the link between reduced liver function in neonates induced by PDE and decreased serum cortisol and IGF1 levels.

CONCLUSIONS

This study demonstrated that low endogenous glucocorticoid level under PDE lead to liver dysplasia by downregulating the H3K27ac level of IGF1 and its expression, ultimately contributing to metabolic syndrome in adult offspring.

Microglia-Derived Insulin-like Growth Factor 1 Is Critical for Neurodevelopment

Insulin-like growth factor 1 (IGF-1) is a peptide hormone essential for the proper development and growth of the organism, as a complete knockout of Igf1 in mice is lethal, causing microcephaly, growth retardation and the defective development of organs. In the central nervous system, neurons and glia have been reported to express Igf1, but their relative importance for postnatal development has not yet been fully defined. In order to address this, here, we obtained mice with a microglia-specific inducible conditional knockout of Igf1. We show that the deficiency in microglial Igf1, starting in the first postnatal week, leads to body and brain growth retardation, severely impaired myelination, changes in microglia numbers, and behavioral abnormalities. These results emphasize the importance of microglial-derived Igf1 for brain development and function and open new perspectives for the investigation of the role of microglial-Igf1 in neurological diseases.

Methylation Status of IGF-Axis Genes in the Placenta of South Indian Neonates with Appropriate and Small for Gestational Age

OBJECTIVE

Altered methylation patterns of insulin-like growth factor (IGF)-axis genes in small for gestational age (SGA) have been reported in different populations. In the present study, we analyzed the methylation status of IGF-axis genes in the placenta of appropriate for gestational age (AGA) and SGA neonates of South Indian women.

METHODS

Placental samples were collected from AGA (n = 40) and SAG (n = 40) neonates. The methylation of IGF-axis genes promoter was analyzed using MS-PCR.

RESULTS

IGF2, H19, IGF1, and IGFR1 genes promoter methylation was 2.5, 1.5, 5, and 7.5% lower in SGA compared to AGA, respectively. Co-methylation of IGF-axis genes promoter was 40% and 20% in AGA and SGA, respectively. IGF-axis gene promoter methylation significantly (p < 0.05) influenced the levels of IGFBP3 protein, birth weight, mitotic index, gestational weeks, and IGFR1 and IGFR2 gene expression.

CONCLUSION

IGF-axis genes methylation was lower in SGA than in AGA, and the methylation significantly influenced the IGF-axis components.

Nanotechnological approaches for the treatment of placental dysfunction: recent trends and future perspectives

The transitory placenta develops during pregnancy and mediates the blood flow between the mother and the developing baby. Placental dysfunction, including but not limited to placenta accreta spectrum, fetal growth restriction, preeclampsia and gestational trophoblastic disease, arises from abnormal placental development and can result in significant adverse maternal and fetal health outcomes. Unfortunately, there is a lack of treatment alternatives for these disorders. Nanocarriers offer versatility, including extended circulation, organ-specific targeting and intracellular transport, finely tuning therapeutic placental interactions. This thorough review explores nanotechnological strategies for addressing placental disorders, encompassing dysfunction insights, potential drug-delivery targets and recent strides in placenta-targeted nanoparticle (NP) therapies, instilling hope for effective placental malfunction treatment.

Insulin-like growth factor 1 supplementation supports motor coordination and affects myelination in preterm pigs

Introduction

Preterm infants have increased risk of impaired neurodevelopment to which reduced systemic levels of insulin-like growth factor 1 (IGF-1) in the weeks after birth may play a role. Hence, we hypothesized that postnatal IGF-1 supplementation would improve brain development in preterm pigs, used as a model for preterm infants.

Methods

Preterm pigs delivered by cesarean section received recombinant human IGF-1/IGF binding protein-3 complex (rhIGF-1/rhIGFBP-3, 2.25 mg/kg/day) or vehicle from birth to postnatal day 19. Motor function and cognition were assessed by monitoring of in-cage and open field activities, balance beam test, gait parameters, novel object recognition and operant conditioning tests. Collected brains were subject to magnetic resonance imaging (MRI), immunohistochemistry, gene expression analyses and protein synthesis measurements.

Results

The IGF-1 treatment increased cerebellar protein synthesis rates (both in vivo and ex vivo). Performance in the balance beam test was improved by IGF-1 but not in other neurofunctional tests. The treatment decreased total and relative caudate nucleus weights, without any effects to total brain weight or grey/white matter volumes. Supplementation with IGF-1 reduced myelination in caudate nucleus, cerebellum, and white matter regions and decreased hilar synapse formation, without effects to oligodendrocyte maturation or neuron differentiation. Gene expression analyses indicated enhanced maturation of the GABAergic system in the caudate nucleus (decreased NKCC1:KCC2 ratio) with limited effects in cerebellum or hippocampus.

Conclusion

Supplemental IGF-1 during the first three weeks after preterm birth may support motor function by enhancing GABAergic maturation in the caudate nucleus, despite reduced myelination. Supplemental IGF-1 may support postnatal brain development in preterm infants, but more studies are required to identify optimal treatment regimens for subgroups of very or extremely preterm infants.

Genetic Obesity in Pregnant Ay Mice Does Not Affect Susceptibility to Obesity and Food Choice in Offspring

Maternal diet and obesity (MO) may influence taste preferences and increase the susceptibility to obesity in offspring, but the impact of MO per se to these influences is poorly understood. We evaluated the influence of MO on food choice and susceptibility to obesity in offspring when mothers consumed a standard diet (SD). Mice with the Lethal yellow mutation (Ay/a) develop obesity consuming an SD. Metabolic parameters were assessed in pregnant and lactating Ay/a (obesity) and a/a (control) mothers. Metabolic response to the consumption of a sweet–fat diet (SFD: SD, lard, and sweet biscuits) and the choice of components of this diet were evaluated in their male and female offspring. Compared to control mothers, pregnant obese mothers had higher levels of insulin, leptin, and FGF21. MO increased food intake and liver expression of lipogenesis genes in male offspring consuming the SD. SFD consumption caused obesity development and insulin resistance, increased liver expression of glycolytic and lipogenesis genes, and affected hypothalamic expression of anorexigenic and orexigenic genes. In offspring of both sexes, MO had no effect on food choice and metabolic response to SFD intake. Therefore, when obese mothers consume a balanced diet, MO does not affect food choice and development of diet-induced obesity in offspring.

Developmental toxicity and programming alterations of multiple organs in offspring induced by medication during pregnancy

Medication during pregnancy is widespread, but there are few reports on its fetal safety. Recent studies suggest that medication during pregnancy can affect fetal morphological and functional development through multiple pathways, multiple organs, and multiple targets. Its mechanisms involve direct ways such as oxidative stress, epigenetic modification, and metabolic activation, and it may also be indirectly caused by placental dysfunction. Further studies have found that medication during pregnancy may also indirectly lead to multi-organ developmental programming, functional homeostasis changes, and susceptibility to related diseases in offspring by inducing fetal intrauterine exposure to too high or too low levels of maternal-derived glucocorticoids. The organ developmental toxicity and programming alterations caused by medication during pregnancy may also have gender differences and multi-generational genetic effects mediated by abnormal epigenetic modification. Combined with the latest research results of our laboratory, this paper reviews the latest research progress on the developmental toxicity and functional programming alterations of multiple organs in offspring induced by medication during pregnancy, which can provide a theoretical and experimental basis for rational medication during pregnancy and effective prevention and treatment of drug-related multiple fetal-originated diseases.

Low-dose antenatal betamethasone treatment achieves preterm lung maturation equivalent to that of the World Health Organization dexamethasone regimen but with reduced endocrine disruption in a sheep model of pregnancy

BACKGROUND

The intramuscular administration of antenatal steroids to women at risk of preterm delivery achieves high maternal and fetal plasma steroid concentrations, which are associated with adverse effects and may reduce treatment efficacy. We have demonstrated that antenatal steroid efficacy is independent of peak maternofetal steroid levels once exposure is maintained above a low threshold.

OBJECTIVE

This study aimed to test, using a sheep model of pregnancy, whether the low-dose antenatal steroid regimen proposed as part of the Antenatal Corticosteroids for Improving Outcomes in Preterm Newborns trial would achieve preterm lung maturation equivalent to that of the existing World Health Organization dexamethasone treatment regimen, but with reduced risk of adverse outcomes.

STUDY DESIGN

Following ethical review and approval, date-mated ewes with single fetuses received intramuscular injections of either (1) four 6-mg maternal intramuscular injections of dexamethasone phosphate every 12 hours (n=22), (2) 4 2-mg maternal intramuscular injections of betamethasone phosphate every 12 hours (n=21), or (3) 4 2-mL maternal intramuscular injections of saline every 12 hours (n=16). Of note, 48 hours after first injection, (124±1 day), lambs were delivered, ventilated for 30 minutes, and euthanized for sampling. Arterial blood gas, respiratory, hematological, and biochemical data were analyzed for between-group differences with analysis of variance according to distribution and variance, with P<.05 taken as significant.

RESULTS

After 30 minutes of ventilation, lambs from both steroid-treated groups had significant and equivalent improvements in lung function relative to saline control (P<.05). There was no significant difference in arterial blood pH, pO₂, pCO₂, lung compliance, ventilator efficiency index, or lung volume at necropsy with a static pressure of 40 cmH₂O. The messenger RNA expression of surfactant protein (Sp)a, Spb, Spc, Spd, aquaporin (Aqp)1, Aqp5, and sodium channel epithelial 1 subunit beta (Scnn1b) was equivalent between both steroid groups. Maternal and fetal plasma neutrophil, glucose, and fetal plasma C-peptide levels were significantly elevated in the dexamethasone group, relative to the betamethasone group. Fetal plasma insulin-like growth factor 1 was significantly reduced in the dexamethasone group compared with the betamethasone group (P<0.05). Fetal adrenocorticotropic hormone (r=0.53), maternal glucose value (r=-0.52), and fetal glucose values (r=-0.42) were correlated with maternal weight in the betamethasone group (P<.05), whereas fetal pCO₂ and pO₂ were not correlated. There was no significant difference between male and female lamb outcomes in any groups for any of the items evaluated.

CONCLUSION

This study reported that in preterm lambs, a low-dose treatment regimen of 8 mg betamethasone achieves lung maturation equivalent to that of a 24-mg dexamethasone-based regimen, but with smaller perturbations to the maternofetal hypothalamic-pituitary-adrenal axis. These data suggested that given steroid pharmacokinetic differences between sheep and humans, a betamethasone dose of 2 mg may remain above the minimum dose necessary for robust maturation of the preterm lung. Maternal weight-adjusted betamethasone doses might also be a key to reducing perturbations to the maternofetal hypothalamic-pituitary-adrenal axis.

Effect of Ethanol Consumption on the Placenta and Liver of Partially IGF-1-Deficient Mice: The Role of Metabolism via CYP2E1 and the Antioxidant Enzyme System

Simple Summary

Ethanol is the most consumed drug worldwide, even during pregnancy. One of its adverse outcomes is fetal growth restriction, an alteration in development due to decreased IGF-1 levels. Several studies have shown that ethanol can impair the IGF-1 signaling pathway, thus exacerbating IGF-1 adverse effects in both intrauterine and postnatal growth and development. In this manuscript, we used a partially IGF-1-deficient mouse model to demonstrate the key role of IGF-1 in fetal development, as well as ethanol’s adverse effects on CYP2E1 expression levels and the antioxidant enzyme system during pregnancy.

Abstract

Ethanol use during pregnancy is a risk factor for developing adverse outcomes. Its metabolism by cytochrome P450 2E1 (CYP2E1) produces radical oxygen species (ROS), promoting cellular injury and apoptosis. To date, no studies have been conducted to elucidate the teratogenic effects due to both IGF-1 deficiency and ethanol consumption in mice placentas. The aim of this study is to determine the effect of ethanol consumption on the placenta and liver of partially IGF-1-deficient mice, the role of metabolism via CYP2E1, and the antioxidant enzyme system. Heterozygous (HZ, Igf1^+/−) pregnant female mice were given water or 10% ethanol. Wild-type (WT, Igf1^+/+) female mice were used as controls. At gestational day 19, pregnant dams were euthanized, and maternal liver and placentas were collected. Pregnant HZ dams were smaller than controls, and this effect was higher due to ethanol consumption. Cyp2e1 gene was overexpressed in the liver of HZ pregnant dams exposed to ethanol; at the protein level, CYP2E1 is reduced in placentas from all genotypes. The antioxidant enzymatic system was altered by ethanol consumption in both the maternal liver and placenta. The results in this work hint that IGF-1 is involved in intrauterine development because its deficiency exacerbates ethanol’s effects on both metabolism and the placenta.

Abnormal microglial polarization induced by Arid1a deletion leads to neuronal differentiation deficits

OBJECTIVE

Microglia, the prototypical innate immune cells of the central nervous system (CNS), are highly plastic and assume their phenotypes dependent on intrinsically genetic, epigenetic regulation or extrinsically microenvironmental cues. Microglia has been recognized as key regulators of neural stem/progenitor cells (NSPCs) and brain functions. Chromatin accessibility is implicated in immune cell development and functional regulation. However, it is still unknown whether and how chromatin remodelling regulates the phenotypic plasticity of microglia and exerts what kind of effects on NSPCs.

METHODS

We investigated the role of chromatin accessibility in microglia by deleting chromatin remodelling gene Arid1a using microglia-specific Cx3cr1-cre and Cx3cr1-CreERT2 mice. RNA-seq and ATAC-seq were performed to dissect the molecular mechanisms. In addition, we examined postnatal M1/M2 microglia polarization and analysed neuronal differentiation of NSPCs. Finally, we tested the effects of microglial Arid1a deletion on mouse behaviours.

RESULTS

Increased chromatin accessibility upon Arid1a ablation resulted in enhanced M1 microglial polarization and weakened M2 polarization, which led to abnormal neurogenesis and anxiety-like behaviours. Switching the polarization state under IL4 stimulation could rescue abnormal neurogenesis, supporting an essential role for chromatin remodeler ARID1A in balancing microglial polarization and brain functions.

CONCLUSIONS

Our study identifies ARID1A as a central regulator of microglia polarization, establishing a mechanistic link between chromatin remodelling, neurogenesis and mouse behaviours, and highlights the potential development of innovative therapeutics exploiting the innate regenerative capacity of the nervous system.

Targeting Insulin-Like Growth Factor-I in Management of Neurological Disorders

The degradation of neurons marks as the pathological reason for onset of most of the neurological diseases although the functional deficiencies and symptoms may vary. Insulin-like growth factor-I (IGF-I) boosts regeneration of both motor and sensory neurons and thus presents as a potential treatment in management of neurological disorders. IGF-I is a pleiotropic agent which stimulates the survival and outgrowth of neurons accompanied by their motility as well as myelination by glial cells. This hormone has been found to possess neuroprotective properties which is in association with its antioxidant and mitochondrial protection activity. Studying and exploring the signaling pathways which mediate pleotropic responses intracellularly have elucidated significant therapeutic approach in treatment and management of neurological disorders by IGF-I. The current review highlights the role of IGF-I in management of major neurological disorders such as depression, Parkinson's disease, and Alzheimer's disease and also covers the mechanisms involved in the process.

Neonatal cardiac hypertrophy: the role of hyperinsulinism-a review of literature

Hypertrophic cardiomyopathy (HCM) in neonates is a rare and heterogeneous disorder which is characterized by hypertrophy of heart with histological and functional disruption of the myocardial structure/composition. The prognosis of HCM depends on the underlying diagnosis. In this review, we emphasize the importance to consider hyperinsulinism in the differential diagnosis of HCM, as hyperinsulinism is widely associated with cardiac hypertrophy (CH) which cannot be distinguished from HCM on echocardiographic examination. We supply an overview of the incidence and treatment strategies of neonatal CH in a broad spectrum of hyperinsulinemic diseases. Reviewing the literature, we found that CH is reported in 13 to 44% of infants of diabetic mothers, in approximately 40% of infants with congenital hyperinsulinism, in 61% of infants with leprechaunism and in 48 to 61% of the patients with congenital generalized lipodystrophy. The correct diagnosis is of importance since there is a large variation in prognoses and there are various strategies to treat CH in hyperinsulinemic diseases.Conclusion: The relationship between CH and hyperinsulism has implications for clinical practice as it might help to establish the correct diagnosis in neonates with cardiac hypertrophy which has both prognostic and therapeutic consequences. In addition, CH should be recognized as a potential comorbidity which might necessitate treatment in all neonates with known hyperinsulinism.What is Known:• Hyperinsulinism is currently not acknowledged as a cause of hypertrophic cardiomyopathy (HCM) in textbooks and recent Pediatric Cardiomyopathy Registry publications.What is New:• This article presents an overview of the literature of hyperinsulinism in neonates and infants showing that hyperinsulinism is associated with cardiac hypertrophy (CH) in a broad range of hyperinsulinemic diseases.• As CH cannot be distinguished from HCM on echocardiographic examination, we emphasize the importance to consider hyperinsulinism in the differential diagnosis of HCM/CH as establishing the correct diagnosis has both prognostic and therapeutic consequences.

Current Insights into the Role of the Growth Hormone-Insulin-Like Growth Factor System in Short Children Born Small for Gestational Age

BACKGROUND

The reason for the insufficient catch-up growth seen in 10% of children born small for gestational age (SGA) is poorly understood. Disturbances in the growth hormone (GH) - insulin-like growth factor (IGF) axis might underlie this failure to show sufficient catch-up growth.

CONCLUSION

This review summarizes insights gained in the molecular and (epi) genetic mechanisms of the GH-IGF axis in short children born SGA. The most notable anomalies of the IGF system are the lowered IGF-I levels in both cord blood and the placenta, and the increased expression of IGF-binding proteins (IGFBP)-1 and IGFBP-2, which inhibit IGF-I, in the placenta of SGA neonates. These observations suggest a decreased bioactivity of IGF-I in utero. IGF-I levels remain reduced in SGA children with short stature, as well as IGFBP-3 and acid-labile subunit levels. Proteolysis of IGFBP-3 appears to be increased.

Dietary L-arginine supplementation during early gestation of gilts affects conceptuses development

l-arginine supplementation of sows has led to improvement of reproductive performance, but the mechanisms responsible for the positive effects of arginine during gestation on conceptuses survival and development are still poorly understood. Thus, we aimed to evaluate effects of 1.0% l-arginine supplementation (ARG) on phenotypic traits of commercial gilts, embryos and fetuses, concentration of gilts' blood metabolites, expression of developmental and cellular apoptosis genes in conceptuses of 25 and 35 days. At 25 days, IGF1 gene was more expressed in embryos from ARG than in embryos from control gilts (CON) (P = 0.05). At this same gestational age, ARG embryos tended to be heavier compared to CON (P = 0.07) and ARG gilts showed a trend to have a greater arginine concentration in blood plasma (P = 0.06). However, at 35 days of gestation, arginine concentration in blood plasma of ARG gilts tended to be lower compared to CON (P = 0.06) and ARG fetuses showed smaller cephalic-caudal length (P = 0.05). These results indicate that duration of supplementation is determinant for arginine effects, not only on the females performance but also on the conceptuses, since supplementation upregulated IGF1 expression at 25 days, in addition to the reduction of cephalic-caudal length of 35-day fetuses.

Phenotypic Features and Response to GH Treatment of Patients With a Molecular Defect of the IGF-1 Receptor

CONTEXT

The phenotype and response to GH treatment of children with an IGF1R defect is insufficiently known.

OBJECTIVE

To develop a clinical score for selecting children with short stature for genetic testing and evaluate the efficacy of treatment.

DESIGN AND SETTING

Case series with an IGF1R defect identified in a university genetic laboratory.

PATIENTS AND INTERVENTIONS

Of all patients with sufficient clinical data, 18 had (likely) pathogenic mutations (group 1) and 7 had 15q deletions including IGF1R (group 2); 19 patients were treated with GH.

MAIN OUTCOME MEASURES

Phenotype and response to GH treatment.

RESULTS

In groups 1 and 2, mean (range) birth weight, length, and head circumference (HC) SD scores (SDSs) were -2.1 (-3.7 to -0.4), -2.7 (-5.0 to -1.0), and -1.6 (-3.0 to 0.0), respectively. At presentation, height, HC, and serum IGF-1 SDSs were -3.0 (-5.5 to -1.7), -2.5 (-4.2 to -0.5), and +1.2 (-1.3 to 3.2), respectively. Feeding problems were reported in 15 of 19 patients. A clinical score with 76% sensitivity is proposed. After 3 years of GH treatment [1.1 (0.2) mg/m2/d] height gain in groups 1 (n = 12) and 2 (n = 7) was 0.9 SDS and 1.3 SDS (at a mean IGF-1 of 3.5 SDS), less than reported for small for gestational age (1.8 SDS).

CONCLUSION

A clinical score encompassing birth weight and/or length, short stature, microcephaly, and IGF-1 is useful for selecting patients for IGF1R analysis. Feeding problems are common and the growth response to GH treatment is moderate.

Rapid growth is a dominant predictor of hepcidin suppression and declining ferritin in Gambian infants

Iron deficiency and iron deficiency anemia are highly prevalent in low-income countries, especially among young children. Hepcidin is the major regulator of systemic iron homeostasis. It controls dietary iron absorption, dictates whether absorbed iron is made available in circulation for erythropoiesis and other iron-demanding processes, and predicts response to oral iron supplementation. Understanding how hepcidin is itself regulated is therefore important, especially in young children. We investigated how changes in iron-related parameters, inflammation and infection status, seasonality, and growth influenced plasma hepcidin and ferritin concentrations during infancy using longitudinal data from two birth cohorts of infants in rural Gambia (n=114 and n=193). This setting is characterized by extreme seasonality, prevalent childhood anemia, undernutrition, and frequent infection. Plasma was collected from infants at birth and at regular intervals, up to 12 months of age. Hepcidin, ferritin and plasma iron concentrations declined markedly during infancy, with reciprocal increases in soluble transferrin receptor and transferrin concentrations, indicating declining iron stores and increasing tissue iron demand. In cross-sectional analyses at 5 and 12 months of age, we identified expected relationships of hepcidin with iron and inflammatory markers, but also observed significant negative associations between hepcidin and antecedent weight gain. Correspondingly, longitudinal fixed effects modeling demonstrated weight gain to be the most notable dynamic predictor of decreasing hepcidin and ferritin through infancy across both cohorts. Infants who grow rapidly in this setting are at particular risk of depletion of iron stores, but since hepcidin concentrations decrease with weight gain, they may also be the most responsive to oral iron interventions.

Neonatal Morbidities of Fetal Growth Restriction: Pathophysiology and Impact

Being born small lays the foundation for short-term and long-term implications for life. Intrauterine or fetal growth restriction describes the pregnancy complication of pathological reduced fetal growth, leading to significant perinatal mortality and morbidity, and subsequent long-term deficits. Placental insufficiency is the principal cause of FGR, which in turn underlies a chronic undersupply of oxygen and nutrients to the fetus. The neonatal morbidities associated with FGR depend on the timing of onset of placental dysfunction and growth restriction, its severity, and the gestation at birth of the infant. In this review, we explore the pathophysiological mechanisms involved in the development of major neonatal morbidities in FGR, and their impact on the health of the infant. Fetal cardiovascular adaptation and altered organ development during gestation are principal contributors to postnatal consequences of FGR. Clinical presentation, diagnostic tools and management strategies of neonatal morbidities are presented. We also present information on the current status of targeted therapies. A better understanding of neonatal morbidities associated with FGR will enable early neonatal detection, monitoring and management of potential adverse outcomes in the newborn period and beyond.

Genetics of Growth Disorders-Which Patients Require Genetic Testing?

The second 360° European Meeting on Growth Hormone Disorders, held in Barcelona, Spain, in June 2017, included a session entitled Pragmatism vs. Curiosity in Genetic Diagnosis of Growth Disorders, which examined current concepts of genetics and growth in the clinical setting, in terms of both growth failure and overgrowth. For patients with short stature, multiple genes have been identified that result in GH deficiency, which may be isolated or associated with additional pituitary hormone deficiencies, or in growth hormone resistance, primary insulin-like growth factor (IGF) acid-labile subunit deficiency, IGF-I deficiency, IGF-II deficiency, IGF-I resistance, and primary PAPP-A2 deficiency. While genetic causes of short stature were previously thought to primarily be associated with the GH-IGF-I axis, it is now established that multiple genetic anomalies not associated with the GH-IGF-I axis can result in short stature. A number of genetic anomalies have also been shown to be associated with overgrowth, some of which involve the GH-IGF-I axis. In patients with overgrowth in combination with an intellectual disability, two predominant gene families, the epigenetic regulator genes, and PI3K/AKT pathway genes, have now been identified. Specific processes should be followed for decisions on which patients require genetic testing and which genes should be examined for anomalies. The decision to carry out genetic testing should be directed by the clinical process, not merely for research purposes. The intention of genetic testing should be to direct the clinical options for management of the growth disorder.

40 YEARS of IGF1: IGF1: the Jekyll and Hyde of the aging brain

The insulin-like growth factor 1 (IGF1) signaling pathway has emerged as a major regulator of the aging process, from rodents to humans. However, given the pleiotropic actions of IGF1, its role in the aging brain remains complex and controversial. While IGF1 is clearly essential for normal development of the central nervous system, conflicting evidence has emerged from preclinical and human studies regarding its relationship to cognitive function, as well as cerebrovascular and neurodegenerative disorders. This review delves into the current state of the evidence examining the role of IGF1 in the aging brain, encompassing preclinical and clinical studies. A broad examination of the data indicates that IGF1 may indeed play opposing roles in the aging brain, depending on the underlying pathology and context. Some evidence suggests that in the setting of neurodegenerative diseases that manifest with abnormal protein deposition in the brain, such as Alzheimer's disease, reducing IGF1 signaling may serve a protective role by slowing disease progression and augmenting clearance of pathologic proteins to maintain cellular homeostasis. In contrast, inducing IGF1 deficiency has also been implicated in dysregulated function of cognition and the neurovascular system, suggesting that some IGF1 signaling may be necessary for normal brain function. Furthermore, states of acute neuronal injury, which necessitate growth, repair and survival signals to persevere, typically demonstrate salutary effects of IGF1 in that context. Appreciating the dual, at times opposing 'Dr Jekyll' and 'Mr Hyde' characteristics of IGF1 in the aging brain, will bring us closer to understanding its impact and devising more targeted IGF1-related interventions.

The emerging connections between IGF1, the intestinal microbiome, Lactobacillus strains and bone growth

In most animal species, postnatal growth is controlled by conserved insulin/insulin-like growth factor (IGF) signaling. In mammals, juvenile growth is characterized by a longitudinal bone growth resulting from the ossification of the growth plate. This ossification is under IGF1 influence through endocrine and paracrine mechanisms. Moreover, the nutritional status has been largely described as an important factor influencing the insulin/insulin-like growth factor signaling. It is now well established that the gut microbiota modulates the nutrient availability of its host. Hence, studies of the interaction between nutritional status, gut microbiota and bone growth have recently emerged. Here, we review recent findings using experimental models about the impact of gut bacteria on the somatotropic axis and its consequence on the bone growth. We also discuss the perspectives of these studies in opening an entire field for clinical interventions.

Insulin-Like Growth Factor-1 Signaling in Lung Development and Inflammatory Lung Diseases

Insulin-like growth factor-1 (IGF-1) was firstly identified as a hormone that mediates the biological effects of growth hormone. Accumulating data have indicated the role of IGF-1 signaling pathway in lung development and diseases such as congenital disorders, cancers, inflammation, and fibrosis. IGF-1 signaling modulates the development and differentiation of many types of lung cells, including airway basal cells, club cells, alveolar epithelial cells, and fibroblasts. IGF-1 signaling deficiency results in alveolar hyperplasia in humans and disrupted lung architecture in animal models. The components of IGF-1 signaling pathways are potentiated as biomarkers as they are dysregulated locally or systemically in lung diseases, whereas data may be inconsistent or even paradoxical among different studies. The usage of IGF-1-based therapeutic agents urges for more researches in developmental disorders and inflammatory lung diseases, as the majority of current data are collected from limited number of animal experiments and are generally less exuberant than those in lung cancer. Elucidation of these questions by further bench-to-bedside researches may provide us with rational clinical diagnostic approaches and agents concerning IGF-1 signaling in lung diseases.

The growth hormone-insulin-like growth factor-I axis in the diagnosis and treatment of growth disorders

The growth hormone (GH)-insulin-like growth factor (IGF)-I axis is a key endocrine mechanism regulating linear growth in children. While paediatricians have a good knowledge of GH secretion and assessment, understanding and use of measurements of the components of the IGF system are less current in clinical practice. The physiological function of this axis is to increase the anabolic cellular processes of protein synthesis and mitosis, and reduction of apoptosis, with each being regulated in the appropriate target tissue. Measurement of serum IGF-I and IGF-binding protein (IGFBP)-3 concentrations can complement assessment of GH status in the investigation of short stature and contribute to prediction of growth response during GH therapy. IGF-I monitoring during GH therapy also informs the clinician about adherence and provides a safety reference to avoid over-dosing during long-term management.

Congenital Hypopituitarism

Mutations of growth hormone genes and pituitary transcription factors account for a small proportion of cases of severe congenital hypopituitarism. Most cases show characteristic MRI findings of pituitary stalk interruption syndrome. Clinical suspicion should prompt assessment of cortisol, free T4, thyroid-stimulating hormone, and growth hormone levels together with MRI of the hypothalamic and pituitary regions.

CaMKIIα expression in a mouse model of NMDAR hypofunction schizophrenia: Putative roles for IGF-1R and TLR4

Schizophrenia (SCZ) is a neuropsychiatric disorder that is linked to social behavioral deficits and other negative symptoms associated with hippocampal synaptic dysfunction. Synaptic mechanism of schizophrenia is characterized by loss of hippocampal N-Methyl-d-Aspartate Receptor (NMDAR) activity (NMDAR hypofunction) and dendritic spines. Previous studies show that genetic deletion of hippocampal synaptic regulatory calcium-calmodulin dependent kinase II alpha (CaMKIIα) cause synaptic and behavioral defects associated with schizophrenia in mice. Although CaMKIIα is involved in modulation of NMDAR activity, it is equally linked to inflammatory and neurotropin signaling in neurons. Based on these propositions, we speculate that non-neurotransmitter upstream receptors associated with neurotropic and inflammatory signaling activities of CaMKIIα may alter its synaptic function. Besides, how these receptors (i.e. inflammatory and neurotropic receptors) alter CaMKIIα function (phosphorylation) relative to hippocampal NMDAR activity in schizophrenia is poorly understood. Here, we examined the relationship between toll-like receptor (TLR4; inflammatory), insulin-like growth factor receptor 1 (IGF-1R; neurotropic) and CaMKIIα expression in the hippocampus of behaviorally deficient schizophrenic mice after we induced schizophrenia through NMDAR inhibition. Schizophrenia was induced in WT (C57BL/6) mice through intraperitoneal administration of 30mg/Kg ketamine (NMDAR antagonist) for 5days (WT/SCZ). Five days after the last ketamine treatment, wild type schizophrenic mice show deficiencies in sociability and social novelty behavior. Furthermore, there was a significant decrease in hippocampal CaMKIIα (p<0.001) and IGF-1R (p<0.001) expression when assessed through immunoblotting and confocal immunofluorescence microscopy. Additionally, WT schizophrenic mice show an increased percentage of phosphorylated CaMKIIα in addition to upregulated TLR4 signaling (TLR4, NF-κB, and MAPK/ErK) in the hippocampus. To ascertain the functional link between TLR4, IGF-1R and CaMKIIα relative to NMDAR hypofunction in schizophrenia, we created hippocampal-specific TLR4 knockdown mouse using AAV-driven Cre-lox technique (TLR4 KD). Subsequently, we inhibited NMDAR function in TLR4 KD mice in an attempt to induce schizophrenia (TLR4 KD SCZ). Interestingly, IGF-1R and CaMKIIα expressions were preserved in the TLR4 KD hippocampus after attenuation of NMDAR function. Furthermore, TLR4 KD SCZ mice showed no prominent defects in sociability and social novelty behavior when compared with the control (WT). Our results show that a sustained IGF-1R expression may preserve the synaptic activity of CaMKIIα while TLR4 signaling ablates hippocampal CaMKIIα expression in NMDAR hypofunction schizophrenia. Together, we infer that IGF-1R depletion and increased TLR4 signaling are non-neurotransmitter pro-schizophrenic cues that can reduce synaptic CaMKIIα activity in a pharmacologic mouse model of schizophrenia.

Genetic disorders of GH action pathway

While insensitivity to GH (GHI) is characterized by low IGF-I levels, normal or elevated GH levels, and lack of IGF-I response to GH treatment, IGF-I resistance is characterized by elevated IGF-I levels with normal/high GH levels. Several genetic defects are responsible for impairment of GH and IGF-I actions resulting in short stature that could affect intrauterine growth or be present in the postnatal period. The genetic defects affecting GH and/or IGF-I action can be divided into five different groups: GH insensitivity by defects affecting the GH receptor (GHR), the intracellular GH signaling pathway (STAT5B, STAT3, IKBKB, IL2RG, PIK3R1), the synthesis of insulin-like growth factors (IGF1, IGF2), the transport/bioavailability of IGFs (IGFALS, PAPPA2), and defects affecting IGF-I sensitivity (IGF1R). Complete GH insensitivity (GHI) was first reported by Zvi Laron and his colleagues in patients with classical appearance of GH deficiency, but presenting elevated levels of GH. The association of GH insensitivity with several clinical sings of immune-dysfunction and autoimmune dysregulation are characteristic of molecular defects in the intracellular GH signaling pathway (STAT5B, STAT3, IKBKB, IL2RG, PIK3R1). Gene mutations in the IGF1 and IGF2 genes have been described in patients presenting intrauterine growth retardation and postnatal short stature. Molecular defects have also been reported in the IGFALS gene, that encodes the acid-labile subunit (ALS), responsible to stabilize circulating IGF-I in ternary complexes, and more recently in the PAPPA2 gen that encodes the pregnancy-associated plasma protein-A2, a protease that specifically cleaves IGFBP-3 and IGFBP-5 regulating the accessibility of IGFs to their target tissues. Mutations in the IGF1R gene resulted in IGF-I insensitivity in patients with impaired intrauterine and postnatal growth. These studies have revealed novel molecular mechanisms of GH insensitivity/primary IGF-I deficiency beyond the GH receptor gene. In addition, they have also underlined the importance of several players of the GH-IGF axis in the complex system that promotes human growth.

Lower circulating insulin-like growth factor-I is associated with better cognition in females with exceptional longevity without compromise to muscle mass and function

Mutations that reduce somatotropic signaling result in improved lifespan and health-span in model organisms and humans. However, whether reduced circulating insulin-like growth factor-I (IGF-I) level is detrimental to cognitive and muscle function in older adults remains understudied. A cross-sectional analysis was performed in Ashkenazi Jews with exceptional longevity (age ≥95 years). Cognition was assessed using the Mini-Mental State Examination and muscle function with the chair rise test, grip-strength, and gait speed. Muscle mass was estimated using the skeletal muscle index. Serum IGF-I was measured with liquid chromatography mass spectrometry. In gender stratified age-adjusted logistic regression analysis, females with IGF-I levels in the first tertile had lower odds of being cognitively impaired compared to females with IGF-I levels within the upper two tertiles, OR (95% CI) 0.39 (0.19-0.82). The result remained significant after adjustment for multiple parameters. No significant association was identified in males between IGF-I and cognition. No relationship was found between IGF-I tertiles and muscle function and muscle mass in females or males. Lower circulating IGF-I is associated with better cognitive function in females with exceptional longevity, with no detriment to skeletal muscle mass and function.

An essential role for IGF2 in cartilage development and glucose metabolism during postnatal long bone growth

Postnatal bone growth involves a dramatic increase in length and girth. Intriguingly, this period of growth is independent of growth hormone and the underlying mechanism is poorly understood. Recently, an IGF2 mutation was identified in humans with early postnatal growth restriction. Here, we show that IGF2 is essential for longitudinal and appositional murine postnatal bone development, which involves proper timing of chondrocyte maturation and perichondrial cell differentiation and survival. Importantly, the Igf2 null mouse model does not represent a simple delay of growth but instead uncoordinated growth plate development. Furthermore, biochemical and two-photon imaging analyses identified elevated and imbalanced glucose metabolism in the Igf2 null mouse. Attenuation of glycolysis rescued the mutant phenotype of premature cartilage maturation, thereby indicating that IGF2 controls bone growth by regulating glucose metabolism in chondrocytes. This work links glucose metabolism with cartilage development and provides insight into the fundamental understanding of human growth abnormalities.

A novel microglial subset plays a key role in myelinogenesis in developing brain

Microglia are resident macrophages of the central nervous system that contribute to homeostasis and neuroinflammation. Although known to play an important role in brain development, their exact function has not been fully described. Here, we show that in contrast to healthy adult and inflammation‐activated cells, neonatal microglia show a unique myelinogenic and neurogenic phenotype. A CD11c⁺ microglial subset that predominates in primary myelinating areas of the developing brain expresses genes for neuronal and glial survival, migration, and differentiation. These cells are the major source of insulin‐like growth factor 1, and its selective depletion from CD11c⁺ microglia leads to impairment of primary myelination. CD11c‐targeted toxin regimens induced a selective transcriptional response in neonates, distinct from adult microglia. CD11c⁺ microglia are also found in clusters of repopulating microglia after experimental ablation and in neuroinflammation in adult mice, but despite some similarities, they do not recapitulate neonatal microglial characteristics. We therefore identify a unique phenotype of neonatal microglia that deliver signals necessary for myelination and neurogenesis.

The New Genomics: What Molecular Databases Can Tell Us About Human Population Variation and Endocrine Disease

Major recent advances in genetics and genomics present unique opportunities for enhancing our understanding of human physiology and disease predisposition. Here I demonstrate how analysis of genomic information can provide new insights into endocrine systems, using the human growth hormone (GH) signaling pathway as an illustrative example. GH is essential for normal postnatal growth in children, and plays important roles in other biological processes throughout life. GH actions are mediated by the GH receptor, primarily via the JAK2 protein tyrosine kinase and the STAT5B transcription factor, and inactivating mutations in this pathway all lead to impaired somatic growth. Variation in GH signaling genes has been evaluated using DNA sequence data from the Exome Aggregation Consortium, a compendium of information from >60,000 individuals. Results reveal many potential missense and other alterations in the coding regions of GH1, GHR, JAK2, and STAT5B, with most changes being uncommon. The total number of different alleles per gene varied by ~threefold, from 101 for GH1 to 338 for JAK2. Several known disease-linked mutations in GH1, GHR, and JAK2 were present but infrequent in the population; however, three amino acid changes in GHR were sufficiently prevalent (~4% to 44% of chromosomes) to suggest that they are not disease causing. Collectively, these data provide new opportunities to understand how genetically driven variability in GH signaling and action may modify human physiology and disease.

Clinical and biochemical characteristics and bone mineral density of homozygous, compound heterozygous and heterozygous carriers of three novel IGFALS mutations

OBJECTIVE

Acid-labile subunit (ALS) deficiency (ACLSD), caused by homozygous or compound heterozygous IGFALS mutations, is associated with moderate short stature, delayed puberty, low serum IGF-I and ALS and extremely low serum IGFBP-3. Its effect on birth weight, head circumference, bone mineral density (BMD), serum IGF-II and IGFBP-2 is uncertain, as well as the phenotype of heterozygous carriers of IGFALS mutations (partial ACLSD).

DESIGN

From all available members of five Turkish families, carrying three mutations in exon 2 of IGFALS (c.1462G > A, p.Asp488Asn (families A, B, E); c.251A > G, p.Asn84Ser (families C and E) and c.1477del, p.Arg493fs (family D)), clinical, laboratory and BMD data were collected.

METHODS

Auxological and biochemical findings were expressed as SDS for age and gender. Ternary complex formation in serum was investigated by size-exclusion chromatography. BMD using DXA bone densitometry was adjusted for height and age (Ha-BMD z-score).

RESULTS

In ACLSD (n = 24), mean ± s.d. height SDS (-2.7 ± 1.2), head circumference SDS (-2.3 ± 0.5) and body mass index (BMI) (-0.6 ± 1.0 SDS) were lower than those in partial ACLSD (n = 26, P ≤ 0.01) and birth weight SDS (n = 7) tended to be lower (-2.2 ± 1.1 vs -0.6 ± 0.3 in partial ACLSD (P = 0.07)). Serum IGF-I was -3.7 ± 1.4 vs -1.0 ± 1.0, IGF-II: -5.6 ± 0.7 vs -1.3 ± 0.7, ALS: <-4.4 ± 1.2 vs -2.1 ± 0.9 and IGFBP-3: -9.0 ± 1.9 vs -1.6 ± 0.8 SDS respectively (P < 0.001). Ha-BMD z-score was similar and normal in both groups.

CONCLUSIONS

To the known phenotype of ACLSD (i.e. short stature, reduced serum levels of IGF-I and ALS, extremely low serum IGFBP-3 and disturbed ternary complex formation), we add reduced birth weight, head circumference and serum IGF-II.

Large-scale analysis of variation in the insulin-like growth factor family in humans reveals rare disease links and common polymorphisms

The insulin-like growth factors IGF1 and IGF2 are closely related proteins that are essential for normal growth and development in humans and other species and play critical roles in many physiological and pathophysiological processes. IGF actions are mediated by transmembrane receptors and modulated by IGF-binding proteins. The importance of IGF actions in human physiology is strengthened by the rarity of inactivating mutations in their genes and by the devastating impact caused by such mutations on normal development and somatic growth. Large-scale genome sequencing has the potential to provide new insights into human variation and disease susceptibility. Toward this end, the availability of DNA sequence data from 60,706 people through the Exome Aggregation Consortium has prompted the analyses presented here. Results reveal a broad range of potential missense and other alterations in the coding regions of every IGF family gene, but the vast majority of predicted changes were uncommon. The total number of different alleles detected per gene in the population varied over an ∼15-fold range, from 57 for IGF1 to 872 for IGF2R, although when corrected for protein length the rate ranged from 0.22 to 0.59 changes/codon among the 11 genes evaluated. Previously characterized disease-causing mutations in IGF2, IGF1R, IGF2R, or IGFALS all were found in the general population but with allele frequencies of <1:30,000. A few new highly prevalent amino acid polymorphisms were also identified. Collectively, these data provide a wealth of opportunities to understand the intricacies of IGF signaling and action in both physiological and pathological contexts.

Growth deficits in cystic fibrosis mice begin in utero prior to IGF-1 reduction

Growth deficits are common in cystic fibrosis (CF), but their cause is complex, with contributions from exocrine pancreatic insufficiency, pulmonary complications, gastrointestinal obstructions, and endocrine abnormalities. The CF mouse model displays similar growth impairment despite exocrine pancreatic function and in the absence of chronic pulmonary infection. The high incidence of intestinal obstruction in the CF mouse has been suggested to significantly contribute to the observed growth deficits. Previous studies by our group have shown that restoration of the cystic fibrosis transmembrane conductance regulator (CFTR) in the intestinal epithelium prevents intestinal obstruction but does not improve growth. In this study, we further investigate growth deficits in CF and gut-corrected CF mice by assessing insulin-like growth factor 1 (IGF-1). IGF-1 levels were significantly decreased in CF and gut-corrected CF adult mice compared to wildtype littermates and were highly correlated with weight. Interestingly, perinatal IGF-1 levels were not significantly different between CF and wildtype littermates, even though growth deficits in CF mice could be detected late in gestation. Since CFTR has been suggested to play a role in water and nutrient exchange in the placenta through its interaction with aquaporins, we analyzed placental aquaporin expression in late-gestation CF and control littermates. While significant differences were observed in Aquaporin 9 expression in CF placentas in late gestation, there was no evidence of placental fluid exchange differences between CF and control littermates. The results from this study indicate that decreased IGF-1 levels are highly correlated with growth in CF mice, independent of CF intestinal obstruction. However, the perinatal growth deficits that are observed in CF mice are not due to decreased IGF-1 levels or differences in placenta-mediated fluid exchange. Further investigation is necessary to understand the etiology of early growth deficits in CF, as growth has been shown to be a significant factor in disease outcomes.

Relationship between insulin-like growth factor 1, leptin and ghrelin levels and catch-up growth in small for gestational age infants of 27-31 weeks during neonatal intensive care unit admission

AIM

Poor post-natal growth is related to later morbidity and poor cognitive development in preterm infants. We investigated the relationship between plasma insulin-like growth factor 1 (IGF-1), leptin, active ghrelin levels and post-natal growth in preterm infants small for gestational age (SGA).

METHODS

Plasma IGF-1, leptin and active ghrelin levels were measured at birth and at 2, 4, 6 and 8 weeks after birth in 42 very low birthweight (VLBW) infants (born between 27 and 31 weeks of gestation), including 14 SGA infants with extrauterine growth restriction (EUGR), 6 SGA infants without EUGR and 22 appropriate-for-gestational-age infants.

RESULTS

At birth, IGF-1 levels in SGA infants without EUGR did not differ significantly from those in SGA infants with EUGR. However, IGF-1 levels in SGA infants without EUGR were as high as those observed in appropriate-for-gestational-age infants and were significantly different from those in SGA infants with EUGR at 4 and 8 weeks of age. Leptin and ghrelin levels did not differ significantly among the three groups at any time point.

CONCLUSION

IGF-1 is related to catch-up growth in SGA VLBW infants during neonatal intensive care unit admission; however, this does not appear to be the case for leptin and ghrelin. IGF-1 level monitoring may be useful for predicting EUGR in preterm VLBW infants.

Bone Status in a Patient with Insulin-Like Growth Factor-1 Receptor Deletion Syndrome: Bone Quality and Structure Evaluation Using Dual-Energy X-Ray Absorptiometry, Peripheral Quantitative Computed Tomography, and Quantitative Ultrasonography

Haploinsufficiency of the insulin-like growth factor (IGF)-1 receptor (IGF1R) gene is a rare, probably under-diagnosed, cause of short stature. However, the effects of IGF1R haploinsufficiency on glucose metabolism, bone status, and metabolism have rarely been investigated. We report the case of a patient referred to our center at the age of 18 months for short stature, failure to thrive, and Silver-Russell-like phenotype. Genetic analysis did not show hypomethylation of the 11p15.5 region or uniparental disomy of chromosome 7. Growth hormone (GH) stimulation tests revealed GH deficiency, whereas IGF-1 was 248 ng/mL. r-hGH treatment showed only a slight improvement (from -4.4 to -3.5 SDS). At 10 years of age, the child was re-evaluated: CGH-array identified a heterozygous de novo 4.92 Mb deletion in 15q26.2, including the IGF1R gene. Dual-energy X-ray absorptiometry showed a normal bone mineral density z-score, while peripheral quantitative computed tomography revealed reduced cortical and increased trabecular elements. A phalangeal bone quantitative ultrasonography showed significantly reduced amplitude-dependent speed of sound and bone transmission time values. The changes in bone architecture, quality, and metabolism in heterozygous IGF1R deletion patients, support the hypothesis that IGF-1 can be a key factor in bone modeling and accrual.

Insulin-Like Growth Factor 1 and Related Compounds in the Treatment of Childhood-Onset Neurodevelopmental Disorders

Insulin-Like Growth Factor 1 (IGF-1) is a neurotrophic polypeptide with crucial roles to play in Central Nervous System (CNS) growth, development and maturation. Following interrogation of the neurobiology underlying several neurodevelopmental disorders and Autism Spectrum Disorders (ASD), both recombinant IGF-1 (mecasermin) and related derivatives, such as (1-3)IGF-1, have emerged as potential therapeutic approaches. Clinical pilot studies and early reports have supported the safety/preliminary efficacy of IGF-1 and related compounds in the treatment of Rett Syndrome, with evidence mounting for its use in Phelan McDermid Syndrome and Fragile X Syndrome. In ASD, clinical trials are ongoing. Here, we review the role of IGF-1 in the molecular etiologies of these conditions in addition to the accumulating evidence from early clinical studies highlighting the possibility of IGF-1 and related compounds as potential treatments for these childhood-onset neurodevelopmental disorders.

Role of Insulinlike Growth Factor 1 in Fetal Development and in the Early Postnatal Life of Premature Infants

The neonatal period of very preterm infants is often characterized by a difficult adjustment to extrauterine life, with an inadequate nutrient supply and insufficient levels of growth factors, resulting in poor growth and a high morbidity rate. Long-term multisystem complications include cognitive, behavioral, and motor dysfunction as a result of brain damage as well as visual and hearing deficits and metabolic disorders that persist into adulthood. Insulinlike growth factor 1 (IGF-1) is a major regulator of fetal growth and development of most organs especially the central nervous system including the retina. Glucose metabolism in the developing brain is controlled by IGF-1 which also stimulates differentiation and prevents apoptosis. Serum concentrations of IGF-1 decrease to very low levels after very preterm birth and remain low for most of the perinatal development. Strong correlations have been found between low neonatal serum concentrations of IGF-1 and poor brain and retinal growth as well as poor general growth with multiorgan morbidities, such as intraventricular hemorrhage, retinopathy of prematurity, bronchopulmonary dysplasia, and necrotizing enterocolitis. Experimental and clinical studies indicate that early supplementation with IGF-1 can improve growth in catabolic states and reduce brain injury after hypoxic/ischemic events. A multicenter phase II study is currently underway to determine whether intravenous replacement of human recombinant IGF-1 up to normal intrauterine serum concentrations can improve growth and development and reduce prematurity-associated morbidities.

Insulin-like growth factor 1 has multisystem effects on foetal and preterm infant development

Poor postnatal growth after preterm birth does not match the normal rapid growth in utero and is associated with preterm morbidities. Insulin‐like growth factor 1 (IGF‐1) axis is the major hormonal mediator of growth in utero, and levels of IGF‐1 are often very low after preterm birth. We reviewed the role of IGF‐1 in foetal development and the corresponding preterm perinatal period to highlight the potential clinical importance of IGF‐1 deficiency in preterm morbidities.

Conclusion

There is a rationale for clinical trials to evaluate the potential benefits of IGF‐1 replacement in very preterm infants.

Effect of insulin-like growth factor-I during the early postnatal period in intrauterine growth-restricted rats

BACKGROUND

Insulin-like growth factor-I (IGF-I) is essential for perinatal growth and development; low serum IGF-I has been observed during intrauterine growth restriction (IUGR). We investigated the effects of recombinant human (rh) IGF-I in IUGR rats during the early postnatal period.

METHODS

Intrauterine growth restriction was induced by bilateral uterine artery ligation in pregnant rats. IUGR pups were divided into two groups injected daily with rhIGF-I (2 mg/kg; IUGR/IGF-I, n = 16) or saline (IUGR/physiologic saline solution (PSS), n = 16) from postnatal day (PND) 7 to 13. Maternal sham-operated pups injected with saline were used as controls (control, n = 16). Serum IGF-I and IGF binding proteins (IGFBP) 3 and 5 were measured on PND25. The expression of Igf-i, IGF-I receptor (Igf-ir), Igfbp3, and 5 mRNA in the liver and brain was measured using real-time polymerase chain reaction on PND25. Immunohistochemical staining of the liver for IGF expression was performed.

RESULTS

Mean bodyweight on PND3 and PND25 in the IUGR pups (IUGR/IGF-I and IUGR/PSS) was significantly lower than that of the control pups. Serum IGF-I and hepatic Igf-ir mRNA in the IUGR pups were significantly lower than those in the control pups. In the IUGR/IGF-I group, hepatic Igfbp3 mRNA and liver immunohistochemical staining were increased. In the IUGR/PSS and control pups, there were no significant differences between these two groups in serum IGFBP3 and IGFBP5, hepatic Igf-i and Igfbp-5 mRNA, or brain Igf mRNA.

CONCLUSIONS

No benefits on body and brain weight gain but an effective increase in hepatic IGFBP-3 was observed after treatment with 2 mg/kg rhIGF-I during the early postnatal period.

Peri-gestational risk factors for pediatric brain tumors in Neurofibromatosis Type 1

BACKGROUND

Individuals with Neurofibromatosis Type 1 (NF1) are strongly predisposed to developing pediatric brain tumors (PBTs), especially optic pathway gliomas (OPGs). Although developmental factors have been implicated in the origins of PBTs in both human and animal studies, associations between early-life factors and PBTs have not been evaluated in individuals with NF1. Our objective was to evaluate associations between peri-gestational characteristics and PBTs in this population.

METHODS

We conducted a cross-sectional study, ascertaining questionnaire and medical record data for 606 individuals<18years old who enrolled in the NF1 Patient Registry Initiative (NPRI) from 6/9/2011-6/29/2015. One hundred eighty-four individuals had reported PBT diagnoses, including 65 who were identified with OPG diagnoses. Cox proportional hazards regression was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for associations between PBT and OPG diagnoses and peri-gestational characteristics (prematurity, birth weight, parental age, plurality, family history of NF1, assisted reproductive technology, maternal vitamin supplementation, and parental smoking).

RESULTS

We observed no significant associations between any of the assessed characteristics and PBTs overall or OPGs with the exception of birth weight. After controlling for potential confounding variables, we observed a significant positive association between birth weight quartile and OPGs with a HR of 3.32 (95% CI 1.39-7.94) for the fourth (≥3915.5g) compared to the first (≤3020g) quartile (p for trend=0.001).

CONCLUSIONS

Consistent with results for PBTs in the general population, these results suggest that higher birth weights increase OPG risk in individuals with NF1.

The role and interaction of imprinted genes in human fetal growth

Identifying the genetic input for fetal growth will help to understand common, serious complications of pregnancy such as fetal growth restriction. Genomic imprinting is an epigenetic process that silences one parental allele, resulting in monoallelic expression. Imprinted genes are important in mammalian fetal growth and development. Evidence has emerged showing that genes that are paternally expressed promote fetal growth, whereas maternally expressed genes suppress growth. We have assessed whether the expression levels of key imprinted genes correlate with fetal growth parameters during pregnancy, either early in gestation, using chorionic villus samples (CVS), or in term placenta. We have found that the expression of paternally expressing insulin-like growth factor 2 (IGF2), its receptor IGF2R, and the IGF2/IGF1R ratio in CVS tissues significantly correlate with crown–rump length and birthweight, whereas term placenta expression shows no correlation. For the maternally expressing pleckstrin homology-like domain family A, member 2 (PHLDA2), there is no correlation early in pregnancy in CVS but a highly significant negative relationship in term placenta. Analysis of the control of imprinted expression of PHLDA2 gave rise to a maternally and compounded grand-maternally controlled genetic effect with a birthweight increase of 93/155 g, respectively, when one copy of the PHLDA2 promoter variant is inherited. Expression of the growth factor receptor-bound protein 10 (GRB10) in term placenta is significantly negatively correlated with head circumference. Analysis of the paternally expressing delta-like 1 homologue (DLK1) shows that the paternal transmission of type 1 diabetes protective G allele of rs941576 single nucleotide polymorphism (SNP) results in significantly reduced birth weight (−132 g). In conclusion, we have found that the expression of key imprinted genes show a strong correlation with fetal growth and that for both genetic and genomics data analyses, it is important not to overlook parent-of-origin effects.

Primordial dwarfism: overview of clinical and genetic aspects

Primordial dwarfism is a group of genetic disorders which include Seckel Syndrome, Silver-Russell Syndrome, Microcephalic Osteodysplastic Primordial Dwarfism types I/III, II and Meier-Gorlin Syndrome. This genetic disorder group is characterized by intra-uterine growth retardation and post-natal growth abnormalities which occur as a result of disorganized molecular and genomic changes in embryonic stage and, thus, it represents a unique area to study growth and developmental abnormalities. Lot of research has been carried out on different aspects; however, a consolidated review that discusses an overall spectrum of this disorder is not accessible. Recent research in this area points toward important molecular and cellular mechanisms in human body that regulate the complexity of growth process. Studies have emerged that have clearly associated with a number of abnormal chromosomal, genetic and epigenetic alterations that can predispose an embryo to develop PD-associated developmental defects. Finding and associating such fundamental changes to its subtypes will help in re-examination of alleged functions at both cellular and developmental levels and thus reveal the intrinsic mechanism that leads to a balanced growth. Although such findings have unraveled a subtle understanding of growth process, we further require active research in terms of identification of reliable biomarkers for different subtypes as an immediate requirement for clinical utilization. It is hoped that further study will advance the understanding of basic mechanisms regulating growth relevant to human health. Therefore, this review has been written with an aim to present an overview of chromosomal, molecular and epigenetic modifications reported to be associated with different subtypes of this heterogenous disorder. Further, latest findings with respect to clinical and molecular genetics research have been summarized to aid the medical fraternity in their clinical utility, for diagnosing disorders where there are overlapping physical attributes and simultaneously inform about the latest developments in PD biology.

Paternally Inherited IGF2 Mutation and Growth Restriction

In humans, mutations in IGF1 or IGF1R cause intrauterine and postnatal growth restriction; however, data on mutations in IGF2, encoding insulin-like growth factor (IGF) II, are lacking. We report an IGF2 variant (c.191C→A, p.Ser64Ter) with evidence of pathogenicity in a multigenerational family with four members who have growth restriction. The phenotype affects only family members who have inherited the variant through paternal transmission, a finding that is consistent with the maternal imprinting status of IGF2. The severe growth restriction in affected family members suggests that IGF-II affects postnatal growth in addition to prenatal growth. Furthermore, the dysmorphic features of affected family members are consistent with a role of deficient IGF-II levels in the cause of the Silver-Russell syndrome. (Funded by Bundesministerium für Bildung und Forschung and the European Union.).

Insulin-Like Growth Factor-Independent Effects of Growth Hormone on Growth Plate Chondrogenesis and Longitudinal Bone Growth

GH stimulates growth plate chondrogenesis and longitudinal bone growth directly at the growth plate. However, it is not clear yet whether these effects are entirely mediated by the local expression and action of IGF-1 and IGF-2. To determine whether GH has any IGF-independent growth-promoting effects, we generated (TamCart)Igf1r(flox/flox) mice. The systemic injection of tamoxifen in these mice postnatally resulted in the excision of the IGF-1 receptor (Igf1r) gene exclusively in the growth plate. (TamCart)Igf1r(flox/flox) tamoxifen-treated mice [knockout (KO) mice] and their Igf1r(flox/flox) control littermates (C mice) were injected for 4 weeks with GH. At the end of the 4-week period, the tibial growth and growth plate height of GH-treated KO mice were greater than those of untreated C or untreated KO mice. The systemic injection of GH increased the phosphorylation of Janus kinase 2 and signal transducer and activator of transcription 5B in the tibial growth plate of the C and KO mice. In addition, GH increased the mRNA expression of bone morphogenetic protein-2 and the mRNA expression and protein phosphorylation of nuclear factor-κB p65 in both C and KO mice. In cultured chondrocytes transfected with Igf1r small interfering RNA, the addition of GH in the culture medium significantly induced thymidine incorporation and collagen X mRNA expression. In conclusion, our findings demonstrate that GH can promote growth plate chondrogenesis and longitudinal bone growth directly at the growth plate, even when the local effects of IGF-1 and IGF-2 are prevented. Further studies are warranted to elucidate the intracellular molecular mechanisms mediating the IGF-independent, growth-promoting GH effects.

Three novel IGF1R mutations in microcephalic patients with prenatal and postnatal growth impairment

BACKGROUND

IGF1R gene mutations have been associated with varying degrees of intrauterine and postnatal growth retardation, and microcephaly.

OBJECTIVE

To identify and characterize IGF1R gene variations in a cohort of 28 Argentinean children suspected of having IGF-1 insensitivity, who were selected on the basis of the association of pre/postnatal growth failure and microcephaly.

METHODS

The coding sequence and flanking intronic regions of IGF1R gene were amplified and directly sequenced. Functional characterization was performed by two in vitro assays: 1) [Methyl-(3) H] thymidine incorporation into DNA in fibroblast cell primary cultures from patients and controls treated with IGF-1 for 16-24 h. 2) PI3K/Akt pathway was evaluated with phospho-Akt (Ser473) STAR ELISA Kit (Millipore) in fibroblast cultures from patients and controls stimulated with IGF-1 for 10 min. Prepubertal clinical and GH-IGF-1 axis evaluation was followed up.

RESULTS

We identified three novel heterozygous missense mutations in three unrelated patients, de novo p.Arg1256Ser, de novo p.Asn359Tyr and p.Tyr865Cys. In control cells, proliferation assay showed that IGF-1 significantly induced DNA synthesis at 20 h and Akt phosphorylation assay that it significantly stimulated phosphorylation after 10 min (P < 0·05 by anova and Bonferroni Tests). However, no significant increase was observed in any of the three patient fibroblasts in both functional studies. GH therapy growth response in two patients was inconsistent.

CONCLUSION

These variations led to failure of the IGF1R function causing pre- and postnatal growth retardation and microcephaly. Microcephaly should be considered in the evaluation of SGA patients, because it seems to favour the frequency of detection of IGF1R mutations.

Genetic characterisation of a cohort of children clinically labelled as GH or IGF1 insensitive: diagnostic value of serum IGF1 and height at presentation

OBJECTIVE AND DESIGN

GH insensitivity (GHI) encompasses growth failure, low serum IGF1 and normal/elevated serum GH. By contrast, IGF1 insensitivity results in pre- and postnatal growth failure associated with relatively high IGF1 levels. From 2008 to 2013, 72 patients from 68 families (45M), mean age 7.1 years (0.4-17.0) with short stature (mean height SDS -3.9; range -9.4 to -1.5), were referred for sequencing.

METHODS

As a genetics referral centre, we have sequenced appropriate candidate genes (GHR, including its pseudoexon (6Ψ), STAT5B, IGFALS, IGF1, IGF1R, OBSL1, CUL7 and CCDC8) in subjects referred with suspected GHI (n=69) or IGF1 insensitivity (n=3).

RESULTS

Mean serum IGF1 SDS was -2.7 (range -0.9 to -8.2) in GHI patients and 2.0, 3.7 and 4.4 in patients with suspected IGF1 insensitivity. Out of 69 GHI patients, 16 (23%) (19% families) had mutations in GH-IGF1 axis genes: homozygous GHR (n=13; 6 6Ψ, two novel IVS5ds+1 G to A) and homozygous IGFALS (n=3; one novel c.1291delT). In the GHI groups, two homozygous OBSL1 mutations were also identified (height SDS -4.9 and -5.7) and two patients had hypomethylation in imprinting control region 1 in 11p15 or mUPD7 consistent with Silver-Russell syndrome (SRS) (height SDS -3.7 and -4.3). A novel heterozygous IGF1R (c.112G>A) mutation was identified in one out of three (33%) IGF1-insensitive subjects.

CONCLUSION

Genotyping contributed to the diagnosis of children with suspected GHI and IGF1 insensitivity, particularly in the GHI subjects with low serum IGF1 SDS (<-2.0) and height SDS (<-2.5). Diagnoses with similar phenotypes included SRS and 3-M syndrome. In 71% patients, no diagnosis was defined justifying further genetic investigation.

Protein deficiency and intestinal nematode infection in pregnant mice differentially impact fetal growth through specific stress hormones, growth factors, and cytokines

BACKGROUND

Protein deficiency (PD) and intestinal nematode infections commonly co-occur during pregnancy and impair fetal growth, but the complex network of signals has not been explored.

OBJECTIVE

Our objective was to assess those stress hormones, growth factors, and cytokines affected by maternal PD and nematode infection and associated with fetal growth.

METHODS

Using a 2 × 2 factorial design, CD-1 mice, fed protein-sufficient (PS; 24%) or protein-deficient (PD; 6%) isoenergetic diets, were either uninfected or infected every 5 d with Heligmosomoides bakeri, beginning on gestational day (GD) 5. Biomarker concentrations were measured on GD 18 in maternal serum (m), fetal serum (f), and amniotic fluid (af) by using Luminex.

RESULTS

Maternal PD lowered fetal body mass (PS/uninfected 1.25 ± 0.02 g, PS/infected 1.19 ± 0.02 g vs. PD/uninfected 1.11 ± 0.02 g, PD/infected 0.97 ± 0.02 g; P = 0.02), fetal lung (P = 0.005), and liver (P = 0.003) but not brain mass, whereas maternal infection lowered fetal length (PS/uninfected 2.28 ± 0.02 cm, PD/uninfected 2.27 ± 0.03 cm vs. PS/infected 2.21 ± 0.03 cm, PD/infected 2.11 ± 0.02 cm; P = 0.05) and kidney mass (P = 0.04). PD elevated stress hormones (m-adrenocortiotropic hormone, f-corticosterone, af-corticosterone) and reduced insulin-like growth factor 1 in all compartments (P ≤ 0.01), but these were unassociated with fetal mass or length. Fetal mass was positively associated with f-leptin (R(2) = 0.71, P = 0.0001) and negatively with fetal cytokines [tumor necrosis factor-α: R(2) = 0.62, P = 0.001; interleukin-4 (IL-4): R(2) = 0.63, P = 0.0004]. In contrast, maternal infection lowered f-prolactin (P = 0.02) that was positively associated with fetal length (R(2) = 0.43; P = 0.03); no other biomarker was affected by infection. Regression analyses showed associations between organ growth, cytokines, and growth factors: 1) thymus, spleen, heart, and brain with m-IL-10; 2) brain and kidney with f-vascular endothelial growth factor, af-monocyte chemotactic protein 1, af-interferon-γ, and af-eotaxin; and 3) liver and lung with f-leptin and af-corticosterone (all P ≤ 0.02).

CONCLUSIONS

PD and nematode infection impaired fetal mass and linear growth, respectively. Fetal mass, length, and individual organ masses were regulated by different hormones, growth factors, and cytokines.

Neonatal vitamin D and childhood brain tumor risk

Vitamin D deficiency among pregnant women is common. Compelling animal evidence suggests carcinogenic effects of vitamin D deficiency on the brains of offspring; however, the impact of circulating vitamin D [25(OH)D] on childhood brain tumor (CBT) risk has not been previously evaluated. Using linked birth-cancer registry data in Washington State, 247 CBT cases (<15 years at diagnosis; born 1991 or later) were identified. A total of 247 birth year-, sex- and race-matched controls were selected from the remaining birth certificates. Liquid chromatography-tandem mass spectrometry was used to measure circulating levels of vitamin D3 [25(OH)D3] in neonatal dried blood spots. Overall, no significant associations were observed. However, when stratified by median birth weight (3,458 g), there was evidence of increasing risk of CBT with increasing 25(OH)D3 among children in the higher birth weight category. Compared to the lowest quartile (2.8-7.7 ng/mL), odds ratios (ORs) and 95% confidence intervals (CIs) for the second (7.7-<11.0 ng/mL), third (11.0-<14.7 ng/mL) and fourth (14.7-37.0) quartiles of 25(OH)D3 were 1.7 (1.0-3.3), 2.4 (1.2-4.8) and 2.6 (1.2-5.6), respectively. Among children in the lower birth weight category, there was suggestive evidence of a protective effect: ORs and 95% CIs for the second, third and fourth quartiles were 0.9 (0.4-1.9), 0.7 (0.3-1.4) and 0.6 (0.3-1.3), respectively. Any associations of neonatal vitamin D with CBT may be birth weight-specific, suggesting the possible involvement of insulin-like growth factor 1, circulating levels of which have been associated with vitamin D and accelerated fetal growth.

Birth weight is the most important predictor of abnormal retinal vascularisation in moderately preterm infants

AIM

To find predictors of abnormal retinal vascularisation in moderately to late preterm newborn infants considered to have no risk of developing retinopathy of prematurity.

METHODS

Seventy-eight infants (34 girls) were recruited from a longitudinal study of otherwise healthy premature children born at a gestational age of 32 + 0-36 + 6 weeks. Retinal vessel morphology was evaluated at mean postnatal age 7 days. Insulin-like growth factor-I (IGF-I) levels were analysed in umbilical cord blood.

RESULTS

Of the 78 infants, 21 (27%) had abnormal retinal vessel morphology; they had significantly lower median (range) birth weight [1850 g, (1190-3260), vs. 2320, (1330-3580), p < 0.0001], shorter birth length [43.0 cm, (38-49), vs. 46.0, (40-50), p < 0.0001] and smaller head circumference [31.0 cm, (27.7-34.0), vs. 32.0, (27.5-36.5), p = 0.003]. They also had significantly lower gestational age [34 + 1 weeks, (32 + 2-35 + 3), vs. 34 + 6, (32 + 2-36 + 6), p = 0.004] and mean ± SD IGF-I levels (24.6 ± 17.0 μg/L vs. 46.7 ± 21.5, p < 0.0001). A higher percentage of these infants were small for gestational age (57.1% vs. 15.8%, p = 0.001), and maternal hypertension/preeclampsia rates were also higher (47.6% vs. 19.3%, p = 0.03). Step-wise logistic regression showed that birth weight was the strongest predictor of abnormal retinal vascularisation (p < 0.0001, odds ratio 0.040, 95% confidence interval 0.007-0.216).

CONCLUSION

In this population of moderately to late preterm newborns, birth weight appeared to affect the retinal vascular system.