Y It Matters—Sex Differences in Fetal Lung Development

Fetal lung growth predicts the risk for early-life respiratory infections and childhood asthma

BACKGROUND

Early-life respiratory infections and asthma are major health burdens during childhood. Markers predicting an increased risk for early-life respiratory diseases are sparse. Here, we identified the predictive value of ultrasound-monitored fetal lung growth for the risk of early-life respiratory infections and asthma.

METHODS

Fetal lung size was serially assessed at standardized time points by transabdominal ultrasound in pregnant women participating in a pregnancy cohort. Correlations between fetal lung growth and respiratory infections in infancy or early-onset asthma at five years were examined. Machine-learning models relying on extreme gradient boosting regressor or classifier algorithms were developed to predict respiratory infection or asthma risk based on fetal lung growth. For model development and validation, study participants were randomly divided into a training and a testing group, respectively, by the employed algorithm.

RESULTS

Enhanced fetal lung growth throughout pregnancy predicted a lower early-life respiratory infection risk. Male sex was associated with a higher risk for respiratory infections in infancy. Fetal lung growth could also predict the risk of asthma at five years of age. We designed three machine-learning models to predict the risk and number of infections in infancy as well as the risk of early-onset asthma. The models' R2 values were 0.92, 0.90 and 0.93, respectively, underscoring a high accuracy and agreement between the actual and predicted values. Influential variables included known risk factors and novel predictors, such as ultrasound-monitored fetal lung growth.

CONCLUSION

Sonographic monitoring of fetal lung growth allows to predict the risk for early-life respiratory infections and asthma.

The association between sex and neonatal respiratory distress syndrome

BACKGROUND

To investigate the association between sex and neonatal respiratory distress syndrome (NRDS).

METHODS

Neonates born at our hospital and transferred to the neonatal department within 1 h were retrospectively analyzed. Depending on whether they developed NRDS during their hospital stay, the neonates was divided into NRDS and non-NRDS groups. There were 142 neonates in the NRDS group (95 males and 47 females) and 310 neonates in the non-NRDS group (180 males and 140 females). The neonates' data on gestational age (GA), sex, birth weight, white blood cell count (WBC), platelet count (PLT), C-reactive protein (CRP), total immunoglobulin M (total IgM), gestational diabetes mellitus(GDM), antenatal steroids use, meconium-stained amniotic fluid, and preterm premature rupture of membranes(PPROM) were gathered.

RESULTS

452 neonates (265 males and 187 females) were involved for the purpose of collecting basic characteristic. Multivariate analysis, males had a 1.87 times higher risk of NRDS than females (P < 0.05) after controlling for the confounding effects of GA, birth weight, WBC, PLT, CRP, total IgM, GDM, antenatal steroids use, meconium-stained amniotic fluid, and PPROM.

CONCLUSIONS

Sex was associated with NRDS; males had a considerably higher risk of NRDS than females.

[Histology of fetal lungs at different gestational age]

The lecture is devoted to the morphological characteristics of the maturation of lung tissue structures in the fetal period. Fetal histology of the lungs presents the intrauterine development of lung tissue in four successive stages: pseudoglandular, canalicular, saccular and alveolar, each has specific morphological criteria. The following morphological features are predetermined: the development of alveolar epithelium, the ratio of mesenchyme towards the area in alveolar spaces, the degree of proliferation and location of vessels of the microcirculatory bed towards prealveolar partitions. During the fetal period the alveolar columnar epithelium is flattened and differentiates into alveolocytes type I and II, the area of the mesenchyme gradually decreases and by the birth of a full-term newborn kid it is present mainly in the thickness between the alveolar septa, microcirculation vessels, initially laying deep in the thickness of the mesenchymal tissue, gradually proliferate, approach the pre-alveolar epithelium, channeling it with the formation of alveolar capillary membranes. Air exchange in the lung tissue is mainly provided with two factors: the presence of second-order alveolocytes capable of producing surfactant, and a sufficient formation of alveoli as well. This work summarizes the basics of fetal lung histology with the demonstration of histological preparations of the lungs at different stages of intrauterine development.

The impact of maternal asthma on the fetal lung: Outcomes, mechanisms and interventions

Maternal asthma affects up to 17% of pregnancies and is associated with adverse infant, childhood, and adult respiratory outcomes, including increased risks of neonatal respiratory distress syndrome, childhood wheeze and asthma. In addition to genetics, these poor outcomes are likely due to the mediating influence of maternal asthma on the in-utero environment, altering fetal lung and immune development and predisposing the offspring to later lung disease. Maternal asthma may impair glucocorticoid signalling in the fetus, a process critical for lung maturation, and increase fetal exposure to proinflammatory cytokines. Therefore, interventions to control maternal asthma, increase glucocorticoid signalling in the fetal lung, or Vitamin A, C, and D supplementation to improve alveologenesis and surfactant production may be beneficial for later lung function. This review highlights potential mechanisms underlying maternal asthma and offspring respiratory morbidities and describes how pregnancy interventions can promote optimal fetal lung development in babies of asthmatic mothers.

Asthma and Rhinitis Through the Lifespan of Nonpregnant Women

Increasingly, clinical practice guidelines advocate a precision medicine-based approach to care for asthma. This focus requires knowledge of not only different asthma phenotypes and their associated biomarkers but also sex and gender differences through the lifespan. Evidence continues to build in favor of different lifetime prevalence, clinical presentations, responses to management, and long-term prognosis of asthma. Women transition through many biological and psychosocial phases in their lives, all of which may interact with, and influence, their health and well-being. Historically, explanations have focused on hormonal effects on asthma in reproductive life, but a greater understanding of mechanisms starting before birth and changing over a lifetime is now possible, with immunologic, inflammatory, and hormonal factors playing a role. This article describes the evidence for the differences in asthma and rhinitis between men and women at different stages of life, the potential underlying mechanisms that contribute to this, and the implications for management and research. Future research studies should systematically report sex differences in asthma so that this knowledge can be used to develop a personalized approach to care, to achieve best possible outcomes for all.

Prenatal Maternal Stress and Pediatric Asthma Across Development: Adolescent Female-Specific Vulnerability

Prenatal maternal stress (PNMS) is linked to physical sequelae in offspring, including childhood asthma. This study sought to examine the roles of objective and subjective PNMS in the development of asthma at offspring ages 5 and 15. The sample included 815 mother-child dyads from the Mater Misericordiae Mothers' Hospital-University of Queensland Study of Pregnancy. PNMS was measured via retrospective self-report during pregnancy and 3-5 days after birth. Postnatal maternal stress was measured at offspring age 5. Objective PNMS was associated with elevated asthma risk at age 5 (OR 1.21, 95% CI 1.00, 1.45, p = 0.05), albeit not above concurrent postnatal stress. Sex moderated the association between PNMS and asthma at age 15, controlling for postnatal stress. Sex stratified analyses revealed a positive association between objective PNMS and age 15 asthma in females, but not males. Results provide evidence that PNMS may impact asthma outcomes in adolescence.

Postnatal growth restriction impairs rat lung structure and function

The negative impact of nutritional deficits in the development of bronchopulmonary dysplasia is well recognized, yet mechanisms by which nutrition alters lung outcomes and nutritional strategies that optimize development and protect the lung remain elusive. Here, we use a rat model to assess the isolated effects of postnatal nutrition on lung structural development without concomitant lung injury. We hypothesize that postnatal growth restriction (PGR) impairs lung structure and function, critical mediators of lung development, and fatty acid profiles at postnatal day 21 in the rat. Rat pups were cross-fostered at birth to rat dams with litter sizes of 8 (control) or 16 (PGR). Lung structure and function, as well as serum and lung tissue fatty acids, and lung molecular mediators of development, were measured. Male and female PGR rat pups had thicker airspace walls, decreased lung compliance, and increased tissue damping. Male rats also had increased lung elastance, increased lung elastin protein abundance, and lysol oxidase expression, and increased elastic fiber deposition. Female rat lungs had increased conducting airway resistance and reduced levels of docosahexaenoic acid in lung tissue. We conclude that PGR impairs lung structure and function in both male and female rats, with sex-divergent changes in lung molecular mediators of development.

The impact of gender medicine on neonatology: the disadvantage of being male: a narrative review

This narrative non-systematic review addresses the sex-specific differences observed both in prenatal period and, subsequently, in early childhood. Indeed, gender influences the type of birth and related complications. The risk of preterm birth, perinatal diseases, and differences on efficacy for pharmacological and non-pharmacological therapies, as well as prevention programs, will be evaluated. Although male newborns get more disadvantages, the physiological changes during growth and factors like social, demographic, and behavioural reverse this prevalence for some diseases. Therefore, given the primary role of genetics in gender differences, further studies specifically targeted neonatal sex-differences will be needed to streamline medical care and improve prevention programs.

Embryology and anatomy of congenital diaphragmatic hernia

Prenatal and postnatal treatment modalities for congenital diaphragmatic hernia (CDH) continue to improve, however patients still face high rates of morbidity and mortality caused by severe underlying persistent pulmonary hypertension and pulmonary hypoplasia. Though the majority of CDH cases are idiopathic, it is believed that CDH is a polygenic developmental defect caused by interactions between candidate genes, as well as environmental and epigenetic factors. However, the origin and pathogenesis of these developmental insults are poorly understood. Further, connections between disrupted lung development and the failure of diaphragmatic closure during embryogenesis have not been fully elucidated. Though several animal models have been useful in identifying candidate genes and disrupted signalling pathways, more studies are required to understand the pathogenesis and to develop effective preventative care. In this article, we summarize the most recent litterature on disrupted embryological lung and diaphragmatic development associated with CDH.

Meconium Aspiration Syndrome in Animal Models: Inflammatory Process, Apoptosis, and Surfactant Inactivation

Meconium Aspiration Syndrome is a condition that causes respiratory distress in newborns due to occlusion and airway inflammation, and surfactant inactivation by meconium. This condition has been described in animal species such as canids, sheep, cattle, horses, pigs, and marine mammals. In its pathogenesis, the pulmonary epithelium activates a limited inflammatory response initiated by cytokines causing leukocyte chemotaxis, inhibition of phagocytosis, and pathogen destruction. Likewise, cytokines release participates in the apoptosis processes of pneumocytes due to the interaction of angiotensin with cytokines and the caspase pathway. Due to these reactions, the prevalent signs are lung injury, hypoxia, acidosis, and pneumonia with susceptibility to infection. Given the importance of the pathophysiological mechanism of meconium aspiration syndrome, this review aims to discuss the relevance of the syndrome in veterinary medicine. The inflammatory processes caused by meconium aspiration in animal models will be analyzed, and the cellular apoptosis and biochemical processes of pulmonary surfactant inactivation will be discussed.