Understanding the role of placental pathophysiology in the development of bronchopulmonary dysplasia

Electroacupuncture may protect pulmonary dysplasia in offspring with perinatal nicotine exposure by altering maternal gut microbiota and metabolites

Background

Perinatal nicotine exposure (PNE) induces pulmonary dysplasia in offspring and it increases the risk of respiratory diseases both in offspring and across generations. The maternal gut microbiota and its metabolites, such as short-chain fatty acids (SCFAs), can regulate fetal lung development and are susceptible to nicotine exposure. Therefore, modulation of PNE-induced changes in maternal gut microbiota and SCFAs may prevent the occurrence of pulmonary dysplasia in offspring.

Objective

Our previous studies demonstrated that electroacupuncture (EA) ameliorated PNE-induced impairment in offspring lung development. To further our study, we aimed to determine whether the protective effect of EA is associated with the modulation of changes in maternal gut microbiota and SCFAs.

Methods

We observed changes in maternal gut microbiota and serum SCFA levels in both mother and offspring after EA treatment using a PNE rat model. Furthermore, using broad-spectrum antibiotics, we established a pseudo-germ-free PNE rat model to explore whether EA can protect offspring's pulmonary function and lung morphology in the presence of depleted maternal gut microbiota.

Results

Our study revealed that EA increased the community richness (Sobs index) of perinatal nicotine-exposed maternal gut microbiota and the abundance of beneficial bacteria (RF39, Clostridia, Oscillospirales, etc.). This was accompanied by an upregulated serum levels of acetate, butyrate, and total SCFAs in both mother and offspring rats, as well as stimulated expression of SCFA receptors (GPR41 and GPR43) in the lung tissue of offspring rats. However, the beneficial effects of EA on offspring pulmonary function (FVC, PEF, PIF, and Cdyn) and lung morphology (alveolar number and MLI) were lost after maternal gut microbiota depletion.

Conclusion

These findings suggest that EA may exert its therapeutic effects on PNE-induced lung phenotype by altering maternal gut microbiota. The likely mechanism involves the associated improvement in serum SCFA levels in both mother and offspring, as well as the upregulation of SCFA receptors in the lung tissue of offspring.

Antenatal steroids enhance long-term neonatal lung outcomes and are associated with placental alterations in experimental chorioamnionitis

Intrauterine inflammation from chorioamnionitis (CA) is associated with placental dysfunction and increased risk of bronchopulmonary dysplasia (BPD), the chronic lung disease of prematurity. Antenatal steroid (ANS) treatment improves early respiratory outcomes for premature infants. However, it remains unclear whether ANS improves long-term respiratory outcomes, and whether these effects are mediated through the improvement of placental dysfunction and/or direct impact on the fetal lung. We hypothesized that maternal ANS therapy preserves long-term lung development and impacts placental structural changes and gene expression in experimental CA with features of BPD. Pregnant rat dams were administered either saline (CTL), intra-amniotic (IA) endotoxin (ETX), ETX plus intramuscular (IM) betamethasone (ETX + BETA), or IM BM alone (BETA) on embryonic day 20 (E20). We collected placental tissue at delivery (E22) and infant lung tissue on the day of life (DOL) 14. In comparison with controls, IA ETX had impaired infant lung growth and function. Maternal BM treatment of ETX-exposed pregnant dams reduced infant total lung resistance by 15.3% (P < 0.05), improved infant lung compliance by 9.5% (P < 0.05), preserved alveolar and vascular growth (P < 0.05), and improved right ventricular hypertrophy (RVH) by 42.4% (P < 0.05). ETX + BETA pregnancies were also associated with normalization of placental spiral artery modification and altered placental gene expression. These included the upregulation of placental prolactin, which has regulatory effects on pregnancy homeostasis and has been clinically associated with decreased BPD risk. The current study identifies parallel lung and placental changes associated with ANS treatment, providing a foundation for future studies to identify alternate antenatal therapies with more specific efficacy for BPD prevention.NEW & NOTEWORTHY We performed parallel neonatal lung and placental analyses in a preclinical model to characterize the impact of antenatal betamethasone in experimental chorioamnionitis. Antenatal steroids improved long-term respiratory outcomes and were associated with concurrent structural and molecular changes in the placenta. This study establishes an important model system for future analyses to evaluate mechanistic links determining whether the long-term impact of antenatal steroids on lung development may be through alteration of placental function.

Prevalence and Risk Factors of Bronchopulmonary Dysplasia Among Very Premature Infants in a Tunisian Neonatal Intensive Care Unit

INTRODUCTION

Bronchopulmonary dysplasia (BPD) stands as the primary chronic respiratory complication in premature infants, posing a substantial public health concern due to its rising prevalence, potential mortality, and socioeconomic burden.

AIM

The aim of this study was to determine the prevalence of BPD in very preterm infants and identify its associated risk factors.

METHODS

We conducted a retrospective, descriptive, and analytical study including all premature infants born between 26 and 31 weeks of gestation age (GA) who survived beyond the 28th day of life, over a five-year period (2017-2021). Patients were divided into two groups based on the presence or absence of BPD, which was defined by the need for oxygen supplementation for at least 28 days.

RESULTS

we included 231 newborns. The prevalence of BPD was 37.7% among survivors on the 28th day of life and 36.7% among those reaching 36 weeks postmenstrual age. BPD was mild, moderate and severe in 25.2%, 4.9% and 6.6% of cases, respectively. Multivariate analysis identified maternal hypertensive disorders (RR=6.15, 95%CI=[2.27-16.67], p<0.001), chorioamnionitis (RR=4.23, 95%CI=[1.25 -14.27], p=0.02), intrauterine growth restriction (IUGR) (RR =20.4, 95%CI=[3.39 -122.66], p=0.001), GA less than 30 weeks (RR=26.97, 95%CI=[10.23 -71.14], p<0.001), and mechanical ventilation (MV) (RR=5.33, 95%CI=[1.95-14.54], p=0.001) as independent factors associated with BPD occurrence. The mortality rate was 10.3% among patients with BPD versus 0.7% in patients without BPD (p = 0.001).

CONCLUSION

Our study revealed a high prevalence of BPD in very preterm infants and identified several independent risk factors such as maternal hypertensive disorders, IUGR, chorioamnionitis, MV, and GA less than 30 weeks.

Bronchopulmonary Dysplasia

Bronchopulmonary dysplasia (BPD) is a chronic lung disease, associated with premature birth, that arises during the infantile period. It is an evolving disease process with an unchanged incidence due to advancements in neonatal care which allow for the survival of premature infants of lower gestational ages and birth weights. Currently, there are few effective interventions to prevent BPD. However, careful attention to BPD phenotypes and comprehensive care provided by an interdisciplinary team have improved care. Interventions early in the disease course hold promise for improving long-term survival and outcomes in adulthood for this high-risk population.

The Factors Associated With Continuous Positive Airway Pressure (CPAP) Failure in Late Preterm and Term Infants and Its Impact on In-Hospital Outcomes

Background and objective Late preterm and term infants commonly require continuous positive airway pressure (CPAP) on admission. However, CPAP failure in this population has not been well studied. Hence, we conducted this study to determine the impact of CPAP failure and identify antenatal factors associated with it in late preterm and term infants. Materials and methods We carried out a single-center retrospective analysis of all inborn infants of ≥34 weeks gestational age (GA) from 2012 to 2019 who received CPAP on admission to the neonatal intensive care unit (NICU). CPAP failure was defined as follows: escalation in the mode of respiratory support, surfactant administration, increase in FiO2 >0.2 above the baseline, or absolute FiO2 >0.4 for ≥3h; within 12h of admission. In-hospital outcomes and perinatal factors were compared between CPAP-failure and success groups. Multivariate stepwise binary logistic regression analysis (LRA) was used to assess the association between antenatal factors and CPAP failure.  Results Of the 272 infants included in the study, 38 (14%) failed CPAP. Infants in the failure group received a longer duration of respiratory support [median (IQR): 3.0 (5.6) vs. 0.5 (0.5)d; p<0.001], and length of stay [9 (9) vs. 4 (4)d; p<0.001]. On LRA, higher GA was associated with reduced odds of CPAP failure. Maternal hypertensive disorders, meconium-stained amniotic fluid, and group B Streptococcus (GBS)-positive status were associated with increased odds of CPAP failure. Conclusions In this cohort of late preterm and term infants, CPAP failure was associated with worse in-hospital outcomes. Lower GA, maternal hypertensive disorders, meconium-stained amniotic fluid, and GBS-positive status were associated with CPAP failure. These data, if replicated in further studies, may help develop individualized respiratory support strategies.

Cord Blood Adductomics Reveals Oxidative Stress Exposure Pathways of Bronchopulmonary Dysplasia

Fetal and neonatal exposures to perinatal oxidative stress (OS) are key mediators of bronchopulmonary dysplasia (BPD). To characterize these exposures, adductomics is an exposure science approach that captures electrophilic addition products (adducts) in blood protein. Adducts are bound to the nucleophilic cysteine loci of human serum albumin (HSA), which has a prolonged half-life. We conducted targeted and untargeted adductomics to test the hypothesis that adducts of OS vary with BPD. We studied 205 preterm infants (≤28 weeks) and 51 full-term infants from an ongoing birth cohort. Infant plasma was collected at birth (cord blood), 1-week, 1-month, and 36-weeks postmenstrual age. HSA was isolated from plasma, trypsin digested, and analyzed using high-performance liquid chromatography-mass spectrometry to quantify previously annotated (known) and unknown adducts. We identified 105 adducts in cord and postnatal blood. A total of 51 known adducts (small thiols, direct oxidation products, and reactive aldehydes) were increased with BPD. Postnatally, serial concentrations of several known OS adducts correlated directly with supplemental oxygen exposure. The application of large-scale adductomics elucidated OS-mediated pathways of BPD. This is the first study to investigate the "neonatal-perinatal exposome" and to identify oxidative stress-related exposure biomarkers that may inform antioxidant strategies to protect the health of future generations of infants.

Early Pulmonary Hypertension in Preterm Infants

Pulmonary hypertension (PH) in preterm neonates has multifactorial pathogenesis with unique characteristics. Premature surfactant-deficient lungs are injured following exposure to positive pressure ventilation and high oxygen concentrations resulting in variable phenotypes of PH. The prevalence of early PH is variable and reported to be between 8% and 55% of extremely preterm infants. Disruption of the lung development and vascular signaling pathway could lead to abnormal pulmonary vascular transition. The management of early PH and the off-label use of selective pulmonary vasodilators continue to be controversial.

Association between Antenatal Antibiotic Exposure and Bronchopulmonary Dysplasia: A Systematic Review and Bayesian Model-Averaged Meta-Analysis

INTRODUCTION

Antenatal antibiotic exposure has been suggested as a risk factor for bronchopulmonary dysplasia (BPD). We aimed to summarize the evidence from randomized controlled trials (RCTs) and observational studies on this potential association.

METHODS

PubMed/Medline and Embase databases were searched. BPD was classified as BPD28 (supplemental oxygen during 28 days or at postnatal day 28), BPD36 (supplemental oxygen at 36 weeks postmenstrual age), BPD36 or death, and BPD-associated pulmonary hypertension (BPD-PH). Bayesian model-averaged (BMA) meta-analysis was used to calculate Bayes factors (BFs). The BF10 is the ratio of the probability of the data under the alternative hypothesis (H1) over the probability of the data under the null hypothesis (H0).

RESULTS

We included 6 RCTs and 27 observational studies (126,614 infants). Regarding BPD28, BMA showed that the evidence in favor of H0 (lack of association with antenatal antibiotics) was weak for the RCTS (BF10 = 0.506, 6 studies) and moderate for the observational studies (BF10 = 0.286, 10 studies). Regarding BPD36, the evidence in favor of H0 was moderate for the RCTs (BF10 = 0.127, 2 studies) and weak for the observational studies (BF10 = 0.895, 14 studies). Evidence in favor of H0 was also weak for the associations with BPD36 or death (BF10 = 0.429, 2 studies) and BPD-PH (BF10 = 0.384, 2 studies). None of the meta-analyses showed evidence in favor of H1.

CONCLUSIONS

The currently available evidence suggests a lack of association between antenatal antibiotics and BPD. However, our results should not be interpreted as an argument for widespread use of antibiotics in the setting of preterm delivery.

Pulmonary phenotypes of bronchopulmonary dysplasia in the preterm infant

Bronchopulmonary dysplasia (BPD) remains the most common complication of premature birth, imposing a significant and potentially life-long burden on patients and their families. Despite advances in our understanding of the mechanisms that contribute to patterns of lung injury and dysfunctional repair, current therapeutic strategies remain non-specific with limited success. Contemporary definitions of BPD continue to rely on clinician prescribed respiratory support requirements at specific time points. While these criteria may be helpful in broadly identifying infants at higher risk of adverse outcomes, they do not offer any precise information regarding the degree to which each compartment of the lung is affected. In this review we will outline the different pulmonary phenotypes of BPD and discuss important features in the pathogenesis, clinical presentation, and management of these frequently overlapping scenarios.

Association between endotypes of prematurity and pharmacological closure of patent ductus arteriosus: A systematic review and meta-analysis

Introduction

Endotypes leading to very and extremely preterm birth are clustered into two groups: infection/inflammation and dysfunctional placentation. We conducted a systematic review of observational studies exploring the association between these two endotypes and the pharmacological closure of patent ductus arteriosus (PDA) induced by cyclooxygenase (COX) inhibitors. Chorioamnionitis represented the infectious-inflammatory endotype, while dysfunctional placentation proxies were hypertensive disorders of pregnancy (HDP) and small for gestational age (SGA) or intrauterine growth restriction.

Methods

PubMed/Medline and Embase databases were searched. The random-effects odds ratio (OR) and 95% confidence interval (CI) were calculated for each association. We included 30 studies (12,639 infants).

Results

Meta-analysis showed a significant association between exposure to HDP and increased rate of pharmacological closure of PDA (17 studies, OR 1.41, 95% CI 1.10-1.81, p = 0.006). In contrast, neither chorioamnionitis (13 studies, OR 0.75, 95% CI 0.47-1.18, p = 0.211) nor SGA (17 studies, OR 1.20, 95% CI 0.96-1.50, p = 0.115) were significantly associated with the response to therapy. Subgroup analyses showed that the higher response to COX inhibitors in the HDP group was significant for indomethacin (OR 1.568, 95% CI 1.147-2.141, p = 0.005) but not for ibuprofen (OR 1.107, 95% CI 0.248-4.392, p = 0.894) or for the studies using both drugs (OR 1.280, 95% CI 0.935-1.751, p = 0.124). However, meta-regression showed that this difference between the drugs was not statistically significant (p = 0.404).

Discussion/Conclusion

Our data suggest that the pathologic condition that triggers prematurity may alter the response to pharmacological treatment of PDA. The DA of infants exposed to HDP appears to be more responsive to COX inhibitors.

Association of patent ductus arteriosus with fetal factors and endotypes of prematurity

During fetal life, the ductus arteriosus (DA) acquires the mechanisms for its postnatal closure following a thorough developmental program. This program can be interrupted by preterm birth and is also susceptible to alteration during fetal life by numerous physiological and pathological stimuli. In this review, we aim to summarize the evidence on how physiological and pathological factors affect DA development, eventually leading to patent DA (PDA). Specifically, we reviewed the associations of sex, race, and pathophysiological pathways leading to very preterm birth (endotypes) with PDA incidence and pharmacological closure. Summary of evidence suggests that there are no male-female differences in the incidence of PDA among very preterm infants. In contrast, risk of developing PDA appears to be higher in infants exposed to chorioamnionitis or who are small for gestational age. Finally, hypertensive disorders of pregnancy may be associated with a better response to pharmacological treatment of PDA. All of this evidence comes from observational studies and therefore associations do not imply causation. The current trend for many neonatologists is to wait for the natural evolution of preterm PDA. Continued research is needed to identify which fetal and perinatal factors modulate the eventual late closure of PDA in very and extremely preterm infants.

Association of Funisitis with Short-Term Outcomes of Prematurity: A Frequentist and Bayesian Meta-Analysis

The fetal systemic inflammatory response associated with intra-amniotic inflammation may play a key role in the pathogenesis of complications of preterm birth. Funisitis is the histologic equivalent of the fetal inflammatory response, whereas chorioamnionitis represents a maternal inflammatory response. We conducted a frequentist and Bayesian model average (BMA) meta-analysis of studies investigating the effects of funisitis on short-term outcomes of prematurity. Thirty-three studies (12,237 infants with gestational age ≤ 34 weeks) were included. Frequentist meta-analysis showed that funisitis was associated with an increased risk of any bronchopulmonary dysplasia (BPD), moderate/severe BPD, retinopathy of prematurity (ROP), intraventricular hemorrhage (IVH), periventricular leukomalacia (PVL), any sepsis, early-onset sepsis (EOS), and mortality. However, Bayesian meta-analysis showed that the evidence in favor of the alternative hypothesis (i.e., funisitis is associated with an increased risk of developing the outcome) was strong for any IVH, moderate for severe IVH and EOS, and weak for the other outcomes. When the control group was restricted to infants having chorioamnionitis without funisitis, the only outcome associated with funisitis was any IVH. In conclusion, our data suggest that the presence of funisitis does not add an additional risk to preterm birth when compared to chorioamnionitis in the absence of fetal inflammatory response.

Gestational Diabetes Mellitus Impedes Fetal Lung Development Through Exosome-Dependent Crosstalk Between Trophoblasts and Lung Epithelial Cells

Background

Fetal lung underdevelopment (FLUD) is associated with neonatal and childhood severe respiratory diseases, among which gestational diabetes mellitus (GDM) play crucial roles as revealed by recent prevalence studies, yet mechanism underlying GDM-induced FLUD, especially the role of trophoblasts, is not all known.

Methods

From the perspective of trophoblast-derived exosomes, we established in vitro, ex vivo, in vivo and GDM trophoblast models. Utilizing placenta-derived exosomes (NUB-exos and GDMUB-exos) isolated from normal and GDM umbilical cord blood plasma and trophoblast-derived exosomes (NC-exos and HG-exos) isolated from HTR8/SVneo trophoblasts medium with/without high glucose treatment, we examined their effects on fetal lung development and biological functions.

Results

We found that, compared with the NUB-exos group, the exosome concentration increased in GDMUB-exos group, and the content of exosomes also changed evidenced by 61 dysregulated miRNAs. After applying these exosomes to A549 alveolar type II epithelial cells, the proliferation and biological functions were suppressed while the proportion of apoptotic cells was increased as compared to the control. In ex vivo studies, we found that GDMUB-exos showed significant suppression on the growth of the fetal lung explants, where the number of terminal buds and the area of explant surface decreased and shrank. Besides, the expression of Fgf10, Vegfa, Flt-1, Kdr and surfactant proteins A, B, C, and D was downregulated in GDMUB-exos group, whilst Sox9 was upregulated. For in vivo studies, we found significant suppression of fetal lung development in GDMUB-exos group. Importantly, we found consistent alterations when we used NC-exos and HG-exos, suggesting a dominant role of trophoblasts in placenta-derived exosome-induced FLUD.

Conclusion

In conclusion, GDM can adversely affect trophoblasts and alter exosome contents, causing crosstalk disorder between trophoblasts and fetal lung epithelial cells and finally leading to FLUD. Findings of this study will shine insight into the theoretical explanation for the pathogenesis of FLUD.

Placing Ureaplasma within the Context of Bronchopulmonary Dysplasia Endotypes and Phenotypes

Different pathophysiological pathways (endotypes), leading to very preterm birth may result in distinct clinical phenotypes of bronchopulmonary dysplasia (BPD). Ureaplasma is a unique player in the pathogenesis of BPD. The interaction between factors inherent to Ureaplasma (virulence, bacterial load, duration of exposure), and to the host (immune response, infection clearance, degree of prematurity, respiratory support, concomitant infections) may contribute to BPD development in a variable manner. The data reviewed herein support the hypothesis that Ureaplasma, as a representative of the infectious/inflammatory endotype, may produce pulmonary damage predominantly in parenchyma, interstitium, and small airways. In contrast, Ureaplasma may have a very limited role in the pathogenesis of the vascular phenotype of BPD. In addition, if Ureaplasma is a key factor in BPD pathogenesis, its eradication by macrolides should prevent BPD. However, various meta-analyses do not show consistent evidence that this is the case. The limitations of current definitions and classifications of BPD, based on respiratory support needs instead of pathophysiology and phenotypes, may explain this and other failures in strategies aimed to prevent BPD. The precise mechanisms through which Ureaplasma infection leads to altered lung development and how these pathways can result in different BPD phenotypes warrant further investigation.