Antenatal steroid therapy for fetal lung maturation: is there an association with childhood asthma?

Elevated third trimester corticosteroid levels are associated with fewer offspring infections

Respiratory infections are a leading cause of morbidity and mortality in early life, and recurrent infections increase the risk of developing chronic diseases. The maternal environment during pregnancy can impact offspring health, but the factors leading to increased infection proneness have not been well characterized during this period. Steroids have been implicated in respiratory health outcomes and may similarly influence infection susceptibility. Our objective was to describe relationships between maternal steroid levels and offspring infection proneness. Using adjusted Poisson regression models, we evaluated associations between sixteen androgenic and corticosteroid metabolites during pregnancy and offspring respiratory infection incidence across two pre-birth cohorts (N = 774 in VDAART and N = 729 in COPSAC). Steroid metabolites were measured in plasma samples from pregnant mothers across all trimesters of pregnancy by ultrahigh-performance-liquid-chromatography/mass-spectrometry. We conducted further inquiry into associations of steroids with related respiratory outcomes: asthma and lung function spirometry. Higher plasma corticosteroid levels in the third trimester of pregnancy were associated with lower incidence of offspring respiratory infections (P = 4.45 × 10-7 to 0.002) and improved lung function metrics (P = 0.020-0.036). Elevated maternal androgens were generally associated with increased offspring respiratory infections and worse lung function, with some associations demonstrating nominal significance at P < 0.05, but these trends were inconsistent across individual androgens. Increased maternal plasma corticosteroid levels in the late second and third trimesters were associated with lower infections and better lung function in offspring, which may represent a potential avenue for intervention through corticosteroid supplementation in late pregnancy to reduce offspring respiratory infection susceptibility in early life.Clinical Trial Registry information: VDAART and COPSAC were originally conducted as clinical trials; VDAART: ClinicalTrials.gov identifier NCT00920621; COPSAC: ClinicalTrials.gov identifier NCT00798226.

Technical Update No. 439: Antenatal Corticosteroids at Late Preterm Gestation

OBJECTIVE

To update recommendations for administration of antenatal corticosteroids in the late preterm period.

TARGET POPULATION

Pregnant individuals at risk of preterm birth from 340 to 366 weeks gestation.

OPTIONS

Administration or non-administration of a single course of antenatal corticosteroids at 340 to 366 weeks gestation.

OUTCOMES

Neonatal morbidity (respiratory distress, hypoglycemia), long-term neurodevelopment, and other long-term outcomes (growth, cardiac/metabolic, respiratory).

BENEFITS, HARMS, AND COSTS

Administration of antenatal corticosteroids from 340 to 366 weeks gestation decreases the risk of neonatal respiratory distress but increases the risk of neonatal hypoglycemia. The long-term impacts of antenatal corticosteroid administration from 340 to 366 weeks gestation are uncertain.

EVIDENCE

For evidence on the neonatal effects of antenatal corticosteroid administration at late preterm gestation, we summarized evidence from the 2020 Cochrane review of antenatal corticosteroids and combined this with evidence from published randomized trials identified by searching Ovid MEDLINE from January 1, 2020, to May 11, 2022. Given the absence of direct evidence on the impact of late preterm antenatal corticosteroid administration on neurodevelopmental outcomes, we summarized evidence on the impact of antenatal corticosteroids across gestational ages on neurodevelopmental outcomes using the following sources: (1) the 2020 Cochrane review; and (2) evidence obtained by searching Ovid MEDLINE, Embase, and Cochrane Central Register of Controlled Trials (CENTRAL) databases from inception to January 5, 2022. We did not apply date or language restrictions. Given the absence of direct evidence on the impact of late preterm antenatal corticosteroid administration on other long-term outcomes, we summarized evidence on the impact of antenatal corticosteroids across gestational ages on other long-term outcomes by combining findings from the 2020 Cochrane review with evidence obtained by searching Ovid MEDLINE for observational studies related to long-term cardiometabolic, respiratory, and growth effects of antenatal corticosteroids from inception to October 22, 2021. We reviewed reference lists of included studies and relevant systematic reviews for additional references. See Appendix A for search terms and summaries.

VALIDATION METHODS

The authors rated the quality of evidence and strength of recommendations using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach. See online Appendix B (Tables B1 for definitions and B2 for interpretations of strong and conditional [weak] recommendations).

INTENDED AUDIENCE

Maternity care providers, including midwives, family physicians, and obstetricians.

SUMMARY STATEMENTS

RECOMMENDATIONS.

Prevalence of asthma in preterm and associated risk factors based on prescription data from the Korean National Health Insurance database

We retrospectively analyzed National Health Insurance claims data (January 2002-December 2018) to determine the asthma prevalence and risk factors among preterm infants born in Korea. Patients with asthma were defined as those with a history of asthma medication prescriptions at least twice per year with International Classification of Diseases, Tenth Edition codes J45 and J46. We enrolled 99,139 preterm infants. The prevalence of asthma among preterm and term infants was 32.7% and 26.9%, 21.2% and 19.1%, 6.7% and 5.9%, 2.0%, and 1.6%, and 2.4% and 1.6% at 2, 5, 10, 15, and 16 years of age, respectively. The relative risk (RR) of asthma in preterm infants was 1.1-fold that in female preterm infants. The RR of asthma medication prescriptions for infants with extreme prematurity was 1.92-fold that of infants with moderate/late pre-term status. Among preterm with bronchopulmonary dysplasia (BPD) and respiratory distress syndrome (RDS) without comorbidities, the RRs for the number of asthma medication prescriptions were 1.34 and 1.06, respectively. This study revealed a higher prevalence of asthma among preterm infants than that in term infants. Male sex, extreme prematurity, BPD, and RDS were identified as risk factors for asthma medication prescriptions in preterm infants.

Forced expiratory flows and diffusion capacity in infants born from mothers with pre-eclampsia

RATIONALE

Animal models suggest pre-eclampsia (Pre-E) affects alveolar development, but data from humans are lacking.

OBJECTIVE

Assess the impact of Pre-E on airway function, diffusion capacity, and respiratory morbidity in preterm and term infants born from mothers with Pre-E.

METHODS

Infants born from mothers with and without Pre-E were recruited for this study; term and preterm infants were included in both cohorts. Respiratory morbidity in the first 12 months of life was assessed through monthly phone surveys. Raised volume rapid thoracoabdominal compression and measurement of diffusion capacity of the lung to carbon monoxide (DLCO) were performed at 6 months corrected age.

MEASUREMENTS AND MAIN RESULTS

There were 146 infants in the Pre-E cohort and 143 in the control cohort. The Pre-E cohort was further divided into nonsevere (N = 41) and severe (N = 105) groups. There was no significant difference in DLCO and DLCO/alveolar volume among the three groups. Forced vital capacity was similar among the three groups, but the nonsevere Pre-E group had significantly higher forced expiratory flows than the other two groups. After adjusting for multiple covariates including prematurity, the severe Pre-E group had a lower risk for wheezing in the first year of life compared to the other two groups.

CONCLUSIONS

Pre-E is not associated with reduced DLCO, lower forced expiratory flows, or increased wheezing in the first year of life. These results differ from animal models and highlight the complex relationships between Pre-E and lung function and respiratory morbidity in human infants.

Congenital Adrenal Hyperplasia Due to Steroid 21-Hydroxylase Deficiency: An Endocrine Society Clinical Practice Guideline

Objective

To update the congenital adrenal hyperplasia due to steroid 21-hydroxylase deficiency clinical practice guideline published by the Endocrine Society in 2010.

Conclusions

The writing committee presents updated best practice guidelines for the clinical management of congenital adrenal hyperplasia based on published evidence and expert opinion with added considerations for patient safety, quality of life, cost, and utilization.

Prenatal Administration of Betamethasone Causes Changes in the T Cell Receptor Repertoire Influencing Development of Autoimmunity

Prenatal glucocorticoids are routinely administered to pregnant women at risk of preterm delivery in order to improve survival of the newborn. However, in half of the cases, birth occurs outside the beneficial period for lung development. Glucocorticoids are potent immune modulators and cause apoptotic death of immature T cells, and we have previously shown that prenatal betamethasone treatment at doses eliciting lung maturation induce profound thymocyte apoptosis in the offspring. Here, we asked if there are long-term consequences on the offspring’s immunity after this treatment. In the non-obese diabetic mouse model, prenatal betamethasone clearly decreased the frequency of pathogenic T cells and the incidence of type 1 diabetes (T1D). In contrast, in the lupus-prone MRL/lpr strain, prenatal glucocorticoids induced changes in the T cell repertoire that resulted in more autoreactive cells. Even though glucocorticoids transiently enhanced regulatory T cell (Treg) development, these cells did not have a protective effect in a model for multiple sclerosis which relies on a limited repertoire of pathogenic T cells for disease induction that were not affected by prenatal betamethasone. We conclude that prenatal steroid treatment, by inducing changes in the T cell receptor repertoire, has unforeseeable consequences on development of autoimmune disease. Our data should encourage further research to fully understand the consequences of this widely used treatment.

Antenatal Dexamethasone Exposure in Preterm Infants Is Associated with Allergic Diseases and the Mental Development Index in Children

Background: Antenatal steroid administration may benefit fetal lung maturity in preterm infants. Although some studies have shown that this treatment may increase asthma in childhood, the correlation between antenatal dexamethasone exposure and allergic diseases remains unclear. The purpose of this study is to investigate the association between antenatal dexamethasone and T cell expression in childhood allergic diseases. Methods: We recruited a cohort of preterm infants born at Kaohsiung Chang Gung Memorial Hospital between 2007 and 2010 with a gestational age of less than 35 weeks and body weight at birth of less than 1500 g. The status of antenatal exposure to steroids and allergic diseases were surveyed using a modified ISAAC questionnaire for subjects aged 2-5 years old. We analyzed Th1/Th2/Th17 expression of mRNA, cytokines (using the Magpix^® my-system), and mental development index (MDI). Results: Among the 40 patients that were followed, the data showed that the antenatal dexamethasone exposure group (N = 24) had a significantly higher incidence of allergic diseases (75.0% vs. 18.8%, p < 0.0001) when compared to the non-dexamethasone exposure group (N = 16), especially with regard to asthma (41.7% vs. 0.0%, p = 0.003) and allergic rhinitis (58.3% vs. 18.8%, p = 0.013), but not atopic dermatitis. No statistical difference was observed in the mRNA expression levels of total white blood cell count between the dexamethasone exposure and non-exposure groups (p > 0.05). However, the asthma group had higher IL-5 levels (p = 0.009), and the MDI was shown to be significantly higher in the dexamethasone exposure group (90.38 ± 3.31 vs. 79.94 ± 3.58, p = 0.043) while no significant difference was found between the PDI of the two groups. Conclusions: Exposure to antenatal dexamethasone in preterm infants will increase their susceptibility to allergic diseases, particularly asthma and allergic rhinitis. Preterm infants' exposure to antenatal dexamethasone also results in higher MDI scores. Such increases in allergic diseases may be related to increased IL-5 and IL-10 levels.

Glucocorticoid genes and the developmental origins of asthma susceptibility and treatment response

Antenatal corticosteroids enhance lung maturation. However, the importance of glucocorticoid genes on early lung development, asthma susceptibility, and treatment response remains unknown. We investigated whether glucocorticoid genes are important during lung development and their role in asthma susceptibility and treatment response. We identified genes that were differentially expressed by corticosteroids in two of three genomic datasets: lymphoblastoid cell lines of participants in the Childhood Asthma Management Program, a glucocorticoid chromatin immunoprecipitation/RNA sequencing experiment, or a murine model; these genes made up the glucocorticoid gene set (GCGS). Using gene expression profiles from 38 human fetal lungs and C57BL/6J murine fetal lungs, we identified developmental genes that were in the top 5% of genes contributing to the top three principal components (PCs) most highly associated with post-conceptional age. Glucocorticoid genes that were enriched in this set of developmental genes were then included in the developmental glucocorticoid gene set (DGGS). We then investigated whether glucocorticoid genes are important during lung development, and their role in asthma susceptibility and treatment response. A total of 232 genes were included in the GCGS. Analysis of gene expression demonstrated that glucocorticoid genes were enriched in lung development (P = 7.02 × 10(-26)). The developmental GCGS was enriched for genes that were differentially expressed between subjects with asthma and control subjects (P = 4.26 × 10(-3)) and were enriched after treatment of subjects with asthma with inhaled corticosteroids (P < 2.72 × 10(-4)). Our results show that glucocorticoid genes are overrepresented among genes implicated in fetal lung development. These genes influence asthma susceptibility and treatment response, suggesting their involvement in the early ontogeny of asthma.

Cross-fostering increases TH1/TH2 expression in a prenatal dexamethasone exposure rat model

BACKGROUND

Prenatal dexamethasone exposure has been reported to increase allergy potential in childhood possibly by interference with normal immunological development in utero. This study investigated the effects of prenatal dexamethasone on T helper cell immune responses in a rat model.

METHODS

Pregnant rats received either dexamethasone 0.1 mg/kg/day or normal saline from gestational day 14-21. Off-springs were cared for by their biological mother, or cross-fostered by the opposing group. Spleen and blood samples were collected at post-natal day 7 and 120 and tested for mRNA expression and plasma cytokine levels of Th1/Th2/Th17 immune response.

RESULTS

Both Th1 (T-bet) and Th2 (GATA-3) mRNA expression were shown to have a significant increase in the prenatal dexamethasone exposure group at day 120 (p<0.05). The plasma levels for Th1 (IFNγ and IL-2) and Th2 (IL-4, IL-5, IL-13) were found to have no significant differences between the two group (p>0.05). The mRNA expression of Th17 (RORγt) showed a significant decrease at post-natal day 120 as well as the plasma level of IL-17A at day 7 (11.21±1.67 vs. 6.23±1.06 pg/ml, p = 0.02). Cross-fostering by a dexamethasone exposed mother resulted in a significant increase in Th1/Th2 mRNA expression (p<0.05) and decrease of Th17.

CONCLUSIONS

Prenatal dexamethasone exposure increased Th1, Th2 and decreased Th17 expression. Cross-fostering by a dexamethasone exposed mother results in more prominent increase of Th1 and Th2 expression.

Effect of prenatal steroid treatment on the developing immune system

Prenatal steroids have an undisputed positive effect of decreasing neonatal morbidity and mortality by improving fetal lung maturation. Some concerns have been raised on long-term consequences on the hypothalamic-pituitary-adrenal axis and cognition, but there are no studies addressing effects on the immune system. The thymus is an essential organ for the development and selection of T cells, and thymocytes are extremely sensitive to steroids. Using a mouse model for prenatal steroid administration, we show here that betamethasone treatment to the mother has a profound effect on the thymus of the offspring. We find the thymus volume reduced, affecting mostly the developing CD4+ CD8+ double-positive thymocytes and a compensatory accelerated transition of the earlier stages to replenish the depleted compartment. This effect lasts for at least 3 days, which correspond to a very relevant period for the selection of the T cell repertoire. Moreover, we show that low doses of betamethasone have similar effects on human thymocytes in vitro. Therefore, further studies are needed to analyze possible long-term consequences of this treatment on the immune system of the offspring.

KEY MESSAGE

Betamethasone administered to the mother before birth reaches the fetal thymus. Prenatal betamethasone results in massive loss of developing thymocytes. The effects of betamethasone on thymus development are visible for several days. Human thymocytes are also sensitive to low doses of betamethasone. Altered thymocyte development around birth may have an effect on the immune system.

Fetal programming: Early-life modulations that affect adult outcomes

Asthma is a common disease, and the number of people diagnosed with it increases every year. Although genetic background and environmental exposures play major roles in the development of asthma, one cannot overlook the developmental origin of adult disease or fetal programming theory. This review examines the social, genetic, and environmental factors that are associated with fetal programming of asthma. We also present recent studies from our laboratory that strengthen these observations. It is our hope that the reader will come away with a current view of fetal programming in asthma.

Antenatal steroid therapy for fetal lung maturation and the subsequent risk of childhood asthma: a longitudinal analysis

This study was designed to test the hypothesis that fetal exposure to corticosteroids in the antenatal period is an independent risk factor for the development of asthma in early childhood with little or no effect in later childhood. A population-based cohort study of all pregnant women who resided in Nova Scotia, Canada, and gave birth to a singleton fetus between 1989 and 1998 was undertaken. After a priori specified exclusions, 80,448 infants were available for analysis. Using linked health care utilization records, incident asthma cases developed after 36 months of age were identified. Extended Cox proportional hazards models were used to estimate hazard ratios while controlling for confounders. Exposure to corticosteroids during pregnancy was associated with a risk of asthma in childhood between 3–5 years of age: adjusted hazard ratio of 1.19 (95% confidence interval: 1.03, 1.39), with no association noted after 5 years of age: adjusted hazard ratio for 5–7 years was 1.06 (95% confidence interval: 0.86, 1.30) and for 8 or greater years was 0.74 (95% confidence interval: 0.54, 1.03). Antenatal steroid therapy appears to be an independent risk factor for the development of asthma between 3 and 5 years of age.