Effect of dexamethasone treatment on serum GH, IGF-I, and the binding proteins IGFBP-1 and -3 in ventilated very preterm infants

Hormonal Determinants of Growth and Weight Gain in the Human Fetus and Preterm Infant

The factors controlling linear growth and weight gain in the human fetus and newborn infant are poorly understood. We review here the changes in linear growth, weight gain, lean body mass, and fat mass during mid- and late gestation and the early postnatal period in the context of changes in the secretion and action of maternal, placental, fetal, and neonatal hormones, growth factors, and adipocytokines. We assess the effects of hormonal determinants on placental nutrient delivery and the impact of preterm delivery on hormone expression and postnatal growth and metabolic function. We then discuss the effects of various maternal disorders and nutritional and pharmacologic interventions on fetal and perinatal hormone and growth factor production, growth, and fat deposition and consider important unresolved questions in the field.

Metabolic-endocrine disruption due to preterm birth impacts growth, body composition, and neonatal outcome

Despite optimized nutrition, preterm-born infants grow slowly and tend to over-accrete body fat. We hypothesize that the premature dissociation of the maternal-placental-fetal unit disrupts the maintenance of physiological endocrine function in the fetus, which has severe consequences for postnatal development. This review highlights the endocrine interactions of the maternal-placental-fetal unit and the early perinatal period in both preterm and term infants. We report on hormonal levels (including tissue, thyroid, adrenal, pancreatic, pituitary, and placental hormones) and nutritional supply and their impact on infant body composition. The data suggest that the premature dissociation of the maternal-placental-fetal unit leads to a clinical picture similar to panhypopituitarism. Further, we describe how the premature withdrawal of the maternal-placental unit, neonatal morbidities, and perinatal stress can cause differences in the levels of growth-promoting hormones, particularly insulin-like growth factors (IGF). In combination with the endocrine disruption that occurs following dissociation of the maternal-placental-fetal unit, the premature adaptation to the extrauterine environment leads to early and fast accretion of fat mass in an immature body. In addition, we report on interventional studies that have aimed to compensate for hormonal deficiencies in infants born preterm through IGF therapy, resulting in improved neonatal morbidity and growth. IMPACT: Preterm birth prematurely dissociates the maternal-placental-fetal unit and disrupts the metabolic-endocrine maintenance of the immature fetus with serious consequences for growth, body composition, and neonatal outcomes. The preterm metabolic-endocrine disruption induces symptoms resembling anterior pituitary failure (panhypopituitarism) with low levels of IGF-1, excessive postnatal fat mass accretion, poor longitudinal growth, and failure to thrive. Appropriate gestational age-adapted nutrition alone seems insufficient for the achievement of optimal growth of preterm infants. Preliminary results from interventional studies show promising effects of early IGF-1 supplementation on postnatal development and neonatal outcomes.

The Impact of Postnatal Systemic Steroids on the Growth of Preterm Infants: A Multicenter Cohort Study

Postnatal steroids, often used to prevent and treat bronchopulmonary dysplasia, may influence the growth of preterm infants, although data are scarce in the literature. This is a multicenter cohort study including surviving preterm infants <32 weeks at birth (n = 17,621) from the Spanish Neonatal Network SEN1500 database, without major congenital malformations. Linear regression models were adjusted for postnatal steroids, respiratory severity course (invasive mechanical ventilation at 28 days), progression to moderate–severe bronchopulmonary dysplasia (O₂ at 36 weeks), length of stay, sex, gestational age and z-scores at birth. A subgroup analysis depending on the timing of administration, ventilation status at 28 days and moderate–severe BPD diagnosis was also performed. Overall, systemic postnatal steroids were not independently associated with poorer weight gain (0.1; 95% CI: −0.05 to 0.2 g/kg/day), linear growth (0; 95% CI: −0.03 to 0.01 cm/week) or head circumference growth (−0.01; 95% CI: −0.02 to 0 cm/week). Patients who received steroids after 28 days or who were not O₂ dependent at 36 weeks after having received steroids gained more weight (0.22; 95% CI: 0.04 to 0.4 and 0.2; 95% CI: 0.004 to 0.5 g/kg/day, respectively). Globally, systemic postnatal steroids had no significant adjusted effect on postnatal growth.

Increased Levels of IGF-1 and Beta2-Microglobulin in Epithelial Lining Fluid of Preterm Newborns Developing Chronic Lung Disease: Effects of rhG-CSF

Insulin-like growth factor-1 (IGF-1) is involved in regulating the TH-l/TH-2 balance, favoring the development of the TH-2 compartment which enhances fibrosis, one of the main characteristics of Chronic Lung Disease (CLD) in premature newborns. Limited data is available concerning a possible association between early epithelial lining fluid (ELF) concentrations of IGF-1 (total and free forms), IGF-binding protein-3 (IGFBP-3), b2-microglobulin (B2M) and subsequent development of CLD in preterm neonates. If neutropenic, preterm neonates are frequently treated with recombinant human Granulocyte Colony Stimulating Factor (rhG-CSF). The objective of the study was to correlate ELF concentrations of IGF-1 and B2M during the first week of life both in non-neutropenic and in rhG-CSF-treated neutropenic preterm neonates, with subsequent development in CLD. Thirty preterm neonates with Respiratory Distress Syndrome (6 with neutropenia) were studied. Eleven out of 24 non-neutropenic preterm infants (46%) and all of the six neutropenic subjects (100%) developed CLD. With the exception of first day values, there was a clear similarity in the behaviors of assayed molecules between non-neutropenic and neutropenic patients developing CLD. Non-neutropenic patients without CLD showed significantly lower values of free IGF-1 and B2M both on days 1 and 3. Total IGF-I and cell counts were different only on the 3rd day. Conclusions: 1) the mechanisms leading to CLD might be mediated by high levels of IGF-family molecules soon after birth 2) B2M could be a marker of increased bronchoalveolar lavage fluid cellularity with potential inflammatory properties 3) G-CSF treatment induces an increased synthesis of IGF-1 molecules by cells recruited in the lung, with possible enhancement of the fibrogenic mechanisms.

Neonatal dexamethasone administration causes progressive renal damage due to induction of an early inflammatory response

Glucocorticoids (GCs) are widely used to prevent chronic lung disease in immature newborns. Emerging evidence indicates that GC exposure in early life may interfere with kidney function and is associated with hypertension in later life. In this study, we have investigated the effect of neonatal dexamethasone (DEX) administration on renal function in rats. Male rats were treated with DEX in the first 3 days after birth, controls received saline (SAL). Severe renal damage associated with premature death was found at 50 wks upon DEX treatment, while renal function and morphology were normal in controls. A subsequent time-course study was performed from 2 days to 32 wks. Compared with controls, neonatal DEX administration led to significant and persistent growth retardation. Progressive proteinuria and increased systolic blood pressure were found from 8 wks onwards in DEX-treated animals. Renal α-SMA gene expression was elevated from wk 24 onwards and morphological fibrosis was noted at 32 wks of age following DEX treatment. Markedly increased renal gene expression of TNF-α and MCP-1 in DEX -treated rats was observed at day 7, probably contributing to the permanent increase in interstitial macrophage numbers that started at 14 days. Permanently elevated renal TGF-β gene expression was induced by DEX administration from 4 wks onwards. Our data indicate that neonatal DEX administration in rats leads to renal failure in later life, presumably due to an early inflammatory trigger that elicits a persistent pro-fibrotic process that eventually results in progressive renal deterioration.

Serum levels of insulin-like growth factor-I and insulin-like growth factor-I binding protein-3: quality control for studies of stored serum

The insulin-like growth factor (IGF) axis, particularly IGF-I and IGF binding protein-3 (IGFBP-3), has been the subject of much attention because of its role in juvenile growth and their association with cancers at several sites. However, epidemiologic studies of IGF-I and IGFBP-3 have had mixed results and several authors have speculated that quality control (QC), sample storage history, and other methodologic concerns could play a role in this heterogeneity. This article documents the results of storage history and QC efforts for a study of IGF-I and IGFBP-3 in 6,226 serum samples from the National Health and Nutrition Examination Survey III (NHANES III). The study was carried out on site at Diagnostic Systems Laboratories in Webster, Texas, using the IGF-I ELISA (DSL 10-5600) and the IGFBP-3 immunoradiometric assay (DSL 6600). A run-in study of assay performance suggested that plates, days, and weeks significantly affected the variance of both assays. Analysis of samples with different storage histories also indicated strong effects of storage history. Serum samples disbursed to laboratories for measurement of diverse analytes and then returned for storage showed reductions in serum IGF-I level averaging 43% and reductions in IGFBP-3 of 25% compared with samples shipped immediately to the repository for long-term storage at -80 degrees C. Therefore, the main study was carried out using samples that had been shipped directly to the National Center for Health Statistics/NHANES collection center for storage. Laboratory analyses of NHANES III and QC samples were carried out over approximately 10 months. QC was monitored through repeated testing of blood samples from six individuals, with two individuals tested twice on each plate. Assay performance was stable over the entire study and coefficients of variation averaged 2% to 3% within plates and approximately 14% for IGF-I and approximately 11.5% for IGFBP-3 over the entire study. Coefficients of variation varied significantly among individual QC subjects, ranging from 12.3% to 17.6% for IGF-I and 8.9% to 12.8% for IGFBP-3. Based on Levy-Jennings plots, approximately 5% of the plates used for IGF-I in the main study were out of compliance. Finally, location on a plate had small but significant effects on IGF-I level. Together, these results highlight the need for care in large studies of putative biomarkers for cancer risk and illustrate some probable sources of heterogeneity in past epidemiologic studies of the IGF axis and cancer.

Insulin-like growth factor-binding protein 3 and hemoglobin concentration in older persons living in the community

A decreased hemoglobin concentration is a common clinical condition in elderly subjects, and in at least 20% of the cases it is not possible to directly attribute the anemia to specific factors. The aim of the present study was to evaluate the relationship of different levels of insulin-like growth factor-binding protein 3 (IGFBP-3) with the blood concentration of hemoglobin in persons aged 80 years and older. Data are from a baseline evaluation of the Aging and Longevity in the Sirente Geographic Area (ilSIRENTE) study (n=253). Analysis of covariance was used to examine the effect of different IGFBP-3 levels on hemoglobin concentration. After adjustment for potential confounding variables, which included age, sex, number of diseases, renal failure, cancer, gastric ulcer, albumin, and iron concentrations, individuals in the group with higher IGFBP-3 concentrations showed a significantly higher mean hemoglobin concentration than participants in the group with lower IGFBP-3 concentrations (13.4 +/- 1.4 g/dL versus 12.9 +/- 1.9 g/dL, respectively; P=.03). In conclusion, the present study has shown that a higher IGFBP-3 level is associated with a higher hemoglobin concentration among older people living in the community. This finding suggests that the growth hormone/IGF axis may play an important role in hematopoiesis, and it may be implicated in the age-related decline in hemoglobin concentration.

Postnatal treatment with dexamethasone perturbs hepatic and cardiac energy metabolism and is associated with a sustained atherogenic plasma lipid profile in suckling rats

Early exposure to glucocorticoids (GC) has been proposed to disturb hepatic and cardiac function in later life. In the present study, we evaluated early metabolic alterations upon GC treatment that may predispose to long-term abnormalities. Rats were injected with dexamethasone (DEX) at d 1, 2, and 3 after birth and controls received saline (SAL). Rats were killed at 2, 7, and 14 d of age. Compared with SAL, DEX induced lower plasma insulin levels, hyperglycemia, hyperketonemia, and dyslipidemia at 2 d. At the same time, DEX treatment significantly increased expression of gluconeogenic and fatty acid oxidation genes in liver and expression of genes involved fatty acid utilization in heart. At 7 d, DEX-treated rats showed insulin resistance with hyperlipidemia, whereas hepatic and cardiac gene expression patterns were largely normalized. Hyperlipidemia and a significantly increased hepatic triglyceride content in DEX-treated rats were prominent at 14 d without large differences in hepatic and cardiac gene expression patterns. Thus, neonatal DEX administration transiently affects cardiac and hepatic gene expression patterns in suckling rats associated with sustained effects on plasma glucose and lipid concentrations. Whether these early effects of DEX contribute to hepatic and cardiac abnormalities at adult age needs further evaluation.

Free insulin-like growth factor-I and cognitive function in older persons living in community

CONTEXT

Increasing evidences from experimental and human studies suggest that the activity of the growth hormone (GH/insulin-like growth factor-I) axis may contribute to the age-related cognitive decline and poor cognition in late life.

OBJECTIVE

The aim of the present study was to evaluate the relationship of total serum free IGF-I and its binding protein-3 with cognitive performance in older persons aged 80 years or older.

DESIGN

Data are from baseline evaluation of the ilSIRENTE study (n=353). Cognitive performance was evaluated using five items enclosed in the Minimum Data Set for Home Care assessment form: short-term memory, procedural memory, cognitive skills in daily decision making, verbal expression, comprehension. Free insulin-like growth factor-I (free IGF-I) and IGF-binding protein-3 (IGFBP-3) in blood were measured. Analysis of covariance (ANCOVA) was used to examine the relationship between cognitive impairment and the serum free IGF-I and IGFBP-3 concentrations, after adjustment for potential confounding variables.

RESULTS

After adjustment for potential confounders, which included age, gender, education, cerebrovascular disease, ischemic heart disease, congestive heart failure, hypertension, diabetes, depression, Parkinson diseases, thyroid diseases, smoking status, alcohol abuse, body mass index, and number of medications, individuals with verbal expression problems (n=20) and individuals with comprehension problems (n=24) had a significantly lower serum levels of readily dissociable IGF-I than participants without cognitive impairments. The serum IGFBP-3 presented the same behavior of free IGF-I.

CONCLUSION

The present study suggests that among old-old subjects living in the community lower levels of total serum free IGF-I and IGFBP-3 are associated with impairment of cognitive performance. This finding suggests that the GH/IGF-I axis may play an important role in the age-related decline of cognitive performance.

Triamcinolone reduces neovascularization, capillary density and IGF-1 receptor phosphorylation in a model of oxygen-induced retinopathy

PURPOSE

To study the effects of intravitreous triamcinolone acetonide (TA) on neovascularization (NV), capillary density, and retinal endothelial cell (REC) viability in a model of oxygen-induced retinopathy (OIR).

METHODS

Newborn rats exposed to OIR underwent intravitreous injections (right eye) at day 14 to achieve intravitreous concentrations of: dexamethasone (DEX) (0.3 mg/mL), triamcinolone (TA; 0.4-4 mg/mL), or PBS. Animals were removed to room air and at day 18, retinal flatmounts were assayed for clock hours of NV, percent peripheral avascular retina, capillary density, apoptosis, and VEGF protein. At day 15, retinas were assayed for insulin-like growth factor (IGF)-1 receptor phosphorylation (IGF-1Rphos). Human RECs exposed to TA were assayed for trypan blue exclusion or activated caspase-3.

RESULTS

TA but not DEX or PBS reduced NV (ANOVA, P < 0.001), capillary density (ANOVA, P < 0.001), and systemic weight gain (ANOVA, P = 0.002). VEGF protein was not different between TA- and PBS-injected or noninjected groups. Apoptosis was not increased in vivo or in vitro between groups, but there was a dose-dependent toxic effect of TA on cultured RECs (P < 0.001). At day 15, retinas from the 4 mg/mL TA-injected OIR group had a trend toward reduced IGF-1Rphos compared with room air-raised PBS- or non-injected OIR groups.

CONCLUSIONS

TA caused dose-dependent reductions in NV, retinal vascularization, and systemic weight gain associated with a reduction in IGF-1Rphos. Long-term studies are needed to assess TA toxicity in vivo. TA doses should be carefully considered before administering the drug in diseases with ongoing retinal vascular development, such as retinopathy of prematurity.

A randomized, placebo-controlled GH trial in very preterm infants who were at risk for bronchopulmonary dysplasia and were treated with dexamethasone

Very preterm infants who develop bronchopulmonary dysplasia are often treated with dexamethasone (DEXA) to wean them from the ventilator. As DEXA has growth-suppressive and catabolic effects, which might have long-term consequences on growth and organ development, we investigated whether high-dose GH treatment could overcome these effects. In a randomized, double-blind, placebo-controlled trial, 30 ventilated very low birth weight infants were assigned to receive either GH or placebo treatment after start of DEXA. DEXA was given for 24 d (starting dose 0.5 mg . kg(-1) . d(-1), tapering off every third day). Simultaneously, high-dose GH (0.3 mg . kg(-1) . d(-1)) or placebo was administered during 6 wk. During high-dose DEXA treatment (dose 0.5-0.3 mg . kg(-1) . d(-1)), no gain in head circumference, weight, crown-heel length, and knee-heel length occurred in the GH and placebo groups. Growth during the 6-wk study period was not different between the GH and the placebo groups. Two patients in the placebo group died, but the number and the severity of adverse effects was not statistically different between the GH and placebo groups. In conclusion, high-dose GH treatment did not improve growth in DEXA-treated very preterm infants and thus cannot be recommended to prevent growth failure in these infants. During high-dose DEXA, a complete growth arrest occurred, including stunting of head growth. Growth in head circumference and weight with lower dose DEXA was comparable to growth after discontinuation of DEXA.