Multiple courses of antenatal corticosteroids are associated with early severe lung disease in preterm neonates

Glucocorticoid metabolism in the developing lung: adrenal-like synthesis pathway

Glucocorticoids (GCs) are essential to normal lung development. They participate in the regulation of important developmental events including morphological changes, and lung maturation leading to the surge of surfactant synthesis by type II epithelial cells. Antenatal GC is administered to mothers at risk of premature delivery to reduce the risk of respiratory distress syndrome (RDS). Sex differences were reported in RDS, in the efficiency of antenatal GC treatment independently of surfactant levels, and in surfactant lipid synthesis. Type II epithelial cell maturation is regulated by epithelial-fibroblast cell-cell communication and involves paracrine factors secreted by fibroblasts under the stimulatory effect of GC. This positive action of GC can be inhibited by androgens through the androgen receptor (AR) present in fibroblasts. In fact, lung development is regulated not only by GC and androgens but also by GC and androgen metabolisms within the developing lung. We recently reviewed the metabolism of androgens in the fetal lung [45]. Here, we review multiple aspects of GC metabolism in the developing lung including inactivation and re-activation by 11β-HSDs, synthesis from the adrenal-like synthesis pathway expressed within the lung and the putative role of CRH and ACTH originating from lung in the regulation of this pathway. This article is part of a Special Issue entitled 'Pregnancy and Steroids'.

Neonatal steroids induce a down-regulation of tenascin-C and elastin and cause a deceleration of the first phase and an acceleration of the second phase of lung alveolarization

Pre- and postnatal corticosteroids are often used in perinatal medicine to improve pulmonary function in preterm infants. To mimic this clinical situation, newborn rats were treated systemically with dexamethasone (Dex), 0.1-0.01 mg/kg/day on days P1-P4. We hypothesized that postnatal Dex may have an impact on alveolarization by interfering with extracellular matrix proteins and cellular differentiation. Morphological alterations were observed on 3D images obtained by high-resolution synchrotron radiation X-ray tomographic microscopy. Alveolarization was quantified stereologically by estimating the formation of new septa between days P4 and P60. The parenchymal expression of tenascin-C (TNC), smooth muscle actin (SMA), and elastin was measured by immunofluorescence and gene expression for TNC by qRT-PCR. After Dex treatment, the first phase of alveolarization was significantly delayed between days P6 and P10, whereas the second phase was accelerated. Elastin and SMA expressions were delayed by Dex treatment, whereas TNC expression was delayed and prolonged. A short course of neonatal steroids impairs the first phase of alveolarization, most likely by altering the TNC and elastin expression. Due to an overshooting catch-up during the second phase of alveolarization, the differences disappear when the animals reach adulthood.

Quantitative ultrasound measurements in premature infants at 1 year of age: the effects of antenatal administered corticosteroids

The aim of this study was to evaluate the effects of antenatally administered glucocorticoids on bone status of preterm infants at 1 year corrected age. The study population consisted of 32 preterm infants with a gestational age of 24-34 weeks. The infants were divided into two groups according to antenatal exposure to corticosteroids. Quantitative ultrasound (QUS) assessment of bone was performed in the study infants at the corrected age of 1 year. Blood levels of carboxy-terminal propeptide of type I procollagen (PICP) and carboxy-terminal telopeptide of type I collagen (ICTP) were measured at birth and at 1 year corrected age. Levels of PICP and ICTP were significantly lower at birth in corticosteroid-exposed neonates (P < 0.05). At corrected age of 12 months ICTP levels remained significantly lower in corticosteroid-exposed infants, but we found no significant difference in levels of the bone-formation marker PICP between corticosteroid-exposed and nonexposed infants. In the majority of participant preterm infants bone speed of sound (SOS) was within age-adjusted normal values of full-term infants. There was no significant difference in bone SOS between exposed and nonexposed infants at corrected age of 12 months. There was no correlation between SOS and levels of bone markers. The results of our study indicate that, despite the suppression of fetal bone turnover at birth in corticosteroid-exposed infants, antenatal glucocorticoid treatment seems to have no long-term impact on bone status of preterm infants assessed by QUS complementary to measurement of bone-turnover markers at 1 year corrected age.

The HELLP syndrome: clinical issues and management. A Review

BACKGROUND

The HELLP syndrome is a serious complication in pregnancy characterized by haemolysis, elevated liver enzymes and low platelet count occurring in 0.5 to 0.9% of all pregnancies and in 10-20% of cases with severe preeclampsia. The present review highlights occurrence, diagnosis, complications, surveillance, corticosteroid treatment, mode of delivery and risk of recurrence.

METHODS

Clinical reports and reviews published between 2000 and 2008 were screened using Pub Med and Cochrane databases.

RESULTS AND CONCLUSION

About 70% of the cases develop before delivery, the majority between the 27th and 37th gestational weeks; the remainder within 48 hours after delivery. The HELLP syndrome may be complete or incomplete. In the Tennessee Classification System diagnostic criteria for HELLP are haemolysis with increased LDH (> 600 U/L), AST (>or= 70 U/L), and platelets < 100 x 10(9)/L. The Mississippi Triple-class HELLP System further classifies the disorder by the nadir platelet counts. The syndrome is a progressive condition and serious complications are frequent. Conservative treatment (>or= 48 hours) is controversial but may be considered in selected cases < 34 weeks' gestation. Delivery is indicated if the HELLP syndrome occurs after the 34th gestational week or the foetal and/or maternal conditions deteriorate. Vaginal delivery is preferable. If the cervix is unfavourable, it is reasonable to induce cervical ripening and then labour. In gestational ages between 24 and 34 weeks most authors prefer a single course of corticosteroid therapy for foetal lung maturation, either 2 doses of 12 mg betamethasone 24 hours apart or 6 mg or dexamethasone 12 hours apart before delivery. Standard corticosteroid treatment is, however, of uncertain clinical value in the maternal HELLP syndrome. High-dose treatment and repeated doses should be avoided for fear of long-term adverse effects on the foetal brain. Before 34 weeks' gestation, delivery should be performed if the maternal condition worsens or signs of intrauterine foetal distress occur. Blood pressure should be kept below 155/105 mmHg. Close surveillance of the mother should be continued for at least 48 hours after delivery.

Multiple courses of antenatal steroids

The benefits and risks of multiple courses of antenatal steroids (ANS) are still unresolved issues. This was a prospective cohort study in a level III neonatal unit. Preterm babies < or = 35 wk gestation were included. Malformations, chronic maternal steroid intake, exchange transfusions prior to cortisol sampling and incomplete ANS courses were exclusion criteria. Subjects were classified into: No course (Group 0), 1 course (group 1), 2 courses (Group 2), > 2 courses (Group 3) of antenatal dexamethasone. The key outcome was adrenal function assessed by basal and post-ACTH cortisol on day 3. Other outcomes were neonatal morbidity, mortality, growth parameters at birth, long term growth and neuro-development. Of 210 eligible babies, 124 were enrolled. 38, 51, 10 and 25 babies belonged to groups 0, 1, 2 and 3 respectively. Basal and post-ACTH serum cortisol did not show any significant difference between groups (p=0.5 and p=0.9 respectively). Incidence of severe HMD requiring ventilation was significantly lower (p=0.02) in multiple course group (combined groups 2 and 3) compared to single course group. There were no differences in other neonatal morbidity, birth OFC and weight between single and multiple ANS groups. Follow up data at a mean age of 22 mth was available in 59 subjects (69%) belonging to groups 1-3. No differences were noted in the proportion of patients with abnormal neurological examination (p=0.1), abnormal PDI (p=0.9), abnormal MDI (p=0.9) and physical growth between multiple and single course groups. Multiple courses of antenatal dexamethasone resulted in a significant decrease in severe forms of RDS and they did not cause adrenal suppression, decreased growth or impaired neuro-development.

Criteria supporting the study of drugs in the newborn

BACKGROUND

Profound changes in the development and the maturation of neonates' organs and organ systems over variable periods of time potentially place neonates at increased risk and/or at different risks compared with adults or older children on exposure to pharmaceutical agents. Most studies of drugs in neonates focus on pharmacokinetic and pharmacodynamic end points and include insufficient numbers of patients to permit evaluation of safety. Only one fourth to one third of approved drugs have received adequate pediatric study to permit labeling for treatment of all appropriate pediatric populations.

OBJECTIVE

The initial goal of the Newborn Drug Prioritization Group was to develop a reproducible, objective process for evaluating drugs most in need of study in the neonatal population based on a universally acceptable priority ranking. The criteria would be applicable across therapeutic classes and would identify those drugs for which immediate study was most needed.

METHODS

Because the therapeutic requirements of the neonate are unique in comparison to older infants and children, the National Institute of Child Health and Human Development and the US Food and Drug Administration (FDA) developed the Newborn Drug Development Initiative to address the limited study of off-patent drugs in newborns. In March 2003, they convened a meeting of pediatric pharmacologists and pediatric specialists from the FDA, the American Academy of Pediatrics, the National Institutes of Health, and academic institutions to discuss how to increase the study of drugs for the newborn. One of the working groups was charged to develop generic criteria for overall prioritization of drugs for study in newborns. Because resources are limited, and not all drugs identified by the 4 clinically focused working groups can receive study at the same time, a process for priority ranking is necessary.

RESULTS

The panel identified 4 general categories containing different numbers of criteria as important for ranking drugs for priority investigation: (1) the disease and indication, including elements such as the potential for adverse outcomes, frequency in newborns, and level of evidence for treatment of newborns; (2) drug characteristics, including elements such as duration of dosing, lack of age-appropriate formulation, clinically relevant drug-drug and drug-disease interactions, and drug disposition in newborns; (3) feasibility and methodology for newborn studies, including both analytical considerations and clinical end points; and (4) the ethical basis for study, including elements to address benefit or harm due to exposure to the study drug, study methodology, and benefit of the new treatment relative to established standard therapy. Based on these categories, a list of criteria to warrant study of a drug in newborns was developed.

CONCLUSION

A process for judicious use of limited resources to rectify these deficiencies remains an urgent public health need.

Levels of bone collagen markers in preterm infants: relation to antenatal glucocorticoid treatment

Although the beneficial effects of antenatally administered glucocorticoids are well documented, data on the potential of adverse consequences are limited. The objective of this study was to determine the effects of antenatally administered glucocorticoids on biochemical markers of bone metabolism of 55 preterm infants with a gestational age of 24-34 weeks who were enrolled in the study. Neonates were divided into two groups according to antenatal exposure to corticosteroids. There were no significant differences between the groups in clinical characteristics and anthropometric variables. We studied blood levels of osteocalcin (OC), carboxy-terminal propeptide of type I procollagen (PICP), and carboxy-terminal telopeptide of type I collagen (ICTP) at the time of delivery, on postnatal day 10, and at 2 and 4 months of life. Comparing the groups, we found statistically significant reduction in PICP levels at birth in corticosteroid-exposed neonates (P < 0.05). The levels of bone markers increased progressively on the first days of life. There were no significant differences between groups in bone markers at 10 days or at 2 and 4 months of life. We found no significant difference for bone markers between groups of infants exposed to single or repeated maternal corticosteroid treatments. In summary, antenatal glucocorticoid treatments are suggested to have a negative impact on fetal bone formation as reflected by low PICP levels at birth. However, this negative effect on bone markers seems to be a temporary effect that subsides on the first days of life and afterward.

Glucocorticoid Metabolism in the Human Fetal Lung: Implications for Lung Development and the Pulmonary Surfactant System

It has been nearly 35 years since Liggins and Howie first reported the benefits of antenatal glucocorticoid (GC) treatment to promote the maturation of the human fetal lung, and nearly that long since Pasqualini and colleagues demonstrated that the human fetal lung actively metabolizes GCs. Since that time, our understanding of the effects of GCs on fetal lung maturation and pulmonary surfactant production has increased dramatically. Similarly, characterization of the enzymes involved in GC metabolism has greatly expanded our understanding of GC signaling in target tissues. In man, the biologically active GC (cortisol) and the biologically inactive GC (cortisone) are interconverted by the tissue-specific expression of the type 1 and type 2 11beta-hydroxysteroid dehydrogenase enzymes (HSD1 and HSD2). Much of the research on GC metabolism in peripheral target tissues has focused on the role of HSD1 in amplifying the effects of GCs in liver and adipose tissue or on the role of HSD2 in blocking the effects of GCs in the kidney and placenta. In contrast, the role of GC metabolism in modulating the effects of GCs on fetal lung maturation and the pulmonary surfactant system in humans is less understood. The goal of this review article is to present a brief overview of the role of GCs in human fetal lung maturation and pulmonary surfactant production, and to familiarize the reader with the biochemistry of the metabolism of natural and synthetic GCs by the HSD enzymes. In addition, we will review data concerning the expression and activity of the HSD enzymes in the human fetal lung and contrast this to what is known about the HSD enzymes in the fetal rodent lung. Although rodents, rabbits, sheep, and several primates have been invaluable model systems for the study of fetal lung development, we have chosen to largely focus this review on human lung, since there are significant differences in GC metabolism between humans and other species.

Dexamethasone inhibits maturation and alters function of monocyte-derived dendritic cells from cord blood

Critically ill infants are treated with dexamethasone (Dx) and other glucocorticoids to reduce inflammation and to promote lung and cardiac function. The neonatal immune system is immature, so neonatal dendritic cells (DCs) might be especially sensitive to glucocorticoid-mediated immunosuppression. To test this, we compared Dx treatment of monocyte-derived DCs from cord (CB) and adult blood (AB). Dx decreased CD1a levels on both AB and CB DCs. CB-treated cells also exhibited decreased expression of CD83 and increased expression of CD14, alterations not observed in AB DCs. Characteristic immature endocytic activity was sustained and enhanced in Dx-treated CB DCs, whereas AB DCs matured normally. Maintenance of endocytosis corresponded with CD14 expression. Dx markedly increased CB DC IL-10, a T cell helper 2 (Th2)-preferential cytokine, while reducing IL-12, a counterbalancing Th1 cytokine. AB DCs were also affected, but increases in IL-10 and decreases in IL-12 were more modest. Dx treatment also inhibited DC-induced T cell proliferation, but CB DCs were inhibited more. In short, neonatal DCs seemed to be especially sensitive to the immunosuppressive effects of Dx as indicated by altered phenotype, endocytic function, ability to stimulate T cells, and cytokine shift favoring Th2. These alterations in DC function are consistent with an increased risk for certain infections and atopic diseases.

Characterization of corticosteroid redosing in an in vitro cell line model

OBJECTIVE

The purpose of this study was to investigate dexamethasone redosing as function of time and dose.

STUDY DESIGN

We studied the effect of 48 hours' exposure to various concentrations of dexamethasone in a human pulmonary adenocarcinoma cell line (H-441). We measured the level of surfactant protein B (SP-B) mRNA by quantitative reverse transcription-PCR after initial dexamethasone exposure, and after redosing, 1 or 2 weeks later. Values are mean +/- SE for 5 experiments. Comparisons were made by Mann-Whitney and Kruskal-Wallis test with significance set at P < .05.

RESULTS

Induction of SP-B mRNA was maximal within 48 hours of the initial dexamethasone exposure. Redosing with the same dexamethasone concentration resulted in levels more than double those initially observed. Redosing with dexamethasone concentration 10 times lower had an effect comparable to that of the initial, higher concentration.

CONCLUSION

Our results suggest a residual effect of the initial exposure that potentiates redosing, allowing significant dose reductions.

Use and misuse of corticosteroids

Corticosteroids are amongst the most common drugs used in clinical medicine. Prudent management of patients is essential to avoid steroid-induced complications.

Association of Lipid Peroxidation with Antenatal Betamethasone and Oxygen Radical Disorders in Preterm Infants

INTRODUCTION

Premature infants are highly susceptible to 'oxygen radical diseases' (ORD), including bronchopulmonary dysplasia, intraventricular hemorrhage/white matter injury, retinopathy of prematurity, and necrotizing enterocolitis. The incidence of ORD is reduced following antenatal treatment with betamethasone. Oxidant-mediated injury is characterized at the cellular level by peroxidation of lipid membranes. This results in the generation of malondialdehyde (MDA), which can be quantified indirectly by measurement of thiobarbituric acid-reacting substances (TBARS). There is currently no effective way to quantify the risk for ORD. In this study, we analyzed the correlation of early urinary MDA and TBARS with prenatal betamethasone administration and with the development of ORD.

METHODS

Preterm infants (<30 weeks gestation, n = 25) born at St. Peter's University Hospital were enrolled. Urine samples were collected during the first 10 days of life and stored at -70 degrees C for 0-21 days. TBARS were quantified by spectrophotometric assay, and malondialdehyde levels measured by HPLC. Subjects were screened for the subsequent development of ORD. Betamethasone administration was defined as one or more doses > or =24 h prior to delivery.

RESULTS

Urinary MDA levels increased on days 2-3 and 5-10 relative to day 1 from birth. Maximal urinary MDA concentrations were significantly higher in the ORD group compared to controls, and there was a trend toward increased urinary TBARS in the presence of ORD. Infants receiving prenatal betamethasone demonstrated higher maximal urinary TBARS values during the first 10 days of life than control infants. The length of sample storage from 0 to 3 weeks at -70 degrees C did not significantly affect TBARS measurements.

CONCLUSIONS

Elevated urinary MDA measurements in the first 10 days are correlated with the risk for ORD. Urinary TBARS concentrations, which are correlated with MDA measurements, can be quantified rapidly and are stable for short-term storage. Our findings suggest that urinary TBARS may be adaptable as a practical tool for assessing the risk for ORD in neonatal intensive care unit patients, allowing clinicians to optimize the use of preventive strategies. Antenatal betamethasone is associated with increased urinary TBARS in the first 10 days of life, indicating that the protective effects of corticosteroids are not mediated through reductions in oxidant-mediated lipid peroxidation.

Current perspectives on the prevention and management of chronic lung disease in preterm infants

Chronic lung disease (CLD) or bronchopulmonary dysplasia is a recognized sequel of preterm birth. With improving survival of infants at lower gestational ages, the incidence is on the rise. Pathological features of CLD include alveolar maldevelopment, with or without areas of pulmonary fibrosis. Assisted ventilation, infection/inflammation, oxygen administration, and fluid overload are the major risk factors in the evolution of CLD.Interventions, including the treatment of maternal infection, administration of prenatal glucocorticoids, and postnatal surfactant replacement therapy, improve the survival of preterm infants; however, their effect on CLD is difficult to determine. Strategies that have been effective in reducing CLD are the administration of retinol (vitamin A), high frequency oscillatory ventilation, and administration of glucocorticoids. Previous concerns regarding neurological problems associated with high frequency ventilation have not been substantiated in recent studies. Current recommendations do not advise the routine use of glucocorticoids due to concerns regarding long-term neurodevelopment. Therapies that were found to be ineffective in reducing the incidence of CLD include prenatal thyrotropin, cromolyn sodium (sodium cromoglycate), alpha-1 antitrypsin, superoxide dismutase, tocopherol (vitamin E), ascorbic acid (vitamin C), allopurinol, ambroxol, inositol, inhaled bronchodilators, and fluid restriction. Strategies that may be effective in reducing lung injury and subsequent CLD include avoiding assisted ventilation, lung protective ventilatory maneuvers, permissive hypercapnia, prevention of infection, early aggressive nutrition, and the treatment of a patent ductus arteriosus. The use of inhaled glucocorticoids improves pulmonary dynamics but long-term effects are unknown. The management of infants with established CLD has not been studied adequately, and the role of various ventilatory strategies for infants with established CLD is not clear. Adequate oxygenation should be maintained to prevent hypoxic episodes. Diuretics are helpful during acute decompensation; however, their long-term impact has not been well studied. Provision of adequate nutrition, immunization (routine and against respiratory syncytial virus), follow-up, and monitoring are the key elements in the long-term management of infants with CLD. Future research priorities should be to identify strategies to prevent/treat inflammation and promote the healing processes in the injured lung. The long-term effects of lung-protective ventilation strategies need to be studied.

Repeated courses of antenatal corticosteroids: is it justified?

The benefits of a single course of antenatal corticosteroids on neonatal outcomes are well established. There is, however, much controversy about how long this treatment should continue, and whether repeated courses should be administered if the women remain at risk for preterm delivery 7 days after the initial therapy. This review aims to discuss current evidence on the effectiveness and safety of repeated courses of antenatal corticosteroids.

Antenatal corticosteroids: the good, the bad and the unknown

PURPOSE OF REVIEW

The purpose of this review was to summarize recently published clinical and animal-based studies of antenatal corticosteroids, describe current recommendations for practice, and suggest priority areas for future research.

RECENT FINDINGS

A single course of antenatal corticosteroids is known to improve newborn lung function after preterm birth and to reduce the risk of newborn death. Current evidence from animal and clinical studies suggests that additional numbers of courses do not further improve lung function and are associated with risks of adverse consequences. These risks principally include restricted intrauterine growth, altered brain development, postnatal insulin resistance and changes to the hypothalamic-pituitary-adrenal axis.

SUMMARY

The research challenges in this field are now centred on uncovering the mechanisms by which cortisol is involved in programming the fetus for its future metabolic life, and discovering ways in which the effectiveness and safety of antenatal glucocorticoids can be enhanced.