Thrown off balance: the effect of antenatal inflammation on the developing lung and immune system

Aspects on Oxygenation in Preterm Infants before, Immediately after Birth, and Beyond

BACKGROUND

Oxygen is crucial for life but too little (hypoxia) or too much (hyperoxia) may be fatal or cause lifelong morbidity.

SUMMARY

In this review, we discuss the challenges of balancing oxygen control in preterm infants during fetal development, the first few minutes after birth, in the neonatal intensive care unit and after hospital discharge, where intensive care monitoring and response to dangerous oxygen levels is more often than not, out of reach with current technologies and services.

KEY MESSAGES

Appropriate oxygenation is critically important even from before birth, but at no time is the need to strike a balance more important than during the first few minutes after birth, when body physiology is changing at its most rapid pace. Preterm infants, in particular, have a poor control of oxygen balance. Underdeveloped organs, especially of the lungs, require supplemental oxygen to prevent hypoxia. However, they are also at risk of hyperoxia due to immature antioxidant defenses. Existing evidence demonstrate considerable challenges that need to be overcome before we can ensure safe treatment of preterm infants with one of the most commonly used drugs in newborn care, oxygen.

Association of Antenatal Corticosteroids with Neonatal Outcomes among Very Preterm Infants Born to Mothers with Clinical Chorioamnionitis: A Multicenter Cohort Study

The objective of this study was to assess the relationship of ACS with neonatal outcomes among very preterm infants born to mothers with clinical chorioamnionitis in China. This was a multicenter retrospective cohort study. Study participants included infants born at <32 weeks' gestation with clinical chorioamnionitis and registered in the Chinese Neonatal Network from 1 January 2019 to 31 December 2020. Infants were divided into two groups: any amount of ACS or no administration of ACS. Multivariable generalized linear models using generalized estimating equations were used to assess the association between ACS and neonatal outcomes among the study population. We identified 2193 infants eligible for this study; 1966 (89.6%) infants had received ACS therapy, and 227 (10.4%) had not received any ACS therapy. Among very preterm infants born to mothers with clinical chorioamnionitis, any ACS usage was significantly associated with decreased risks of early death (aRR 0.56, 95% CI 0.32, 0.99) and severe ROP (aRR 0.51, 95% CI 0.28, 0.93) after adjustment for maternal hypertension, gestational age at birth, Caesarean section, being inborn, and administration of systemic antibiotics to the mother within 24 h before birth. In addition, out of the 2193 infants, the placentas of 1931 infants underwent pathological examination with recorded results. Subsequently, 1490 of these cases (77.2%) were diagnosed with histological chorioamnionitis. In 1490 cases of histologic chorioamnionitis, any ACS usage was significantly related to decreased risks of overall mortality (aRR 0.52, 95% CI 0.31, 0.87), severe ROP (aRR 0.47, 95% CI 0.25, 0.97), and respiratory distress syndrome (aRR 0.52, 95% CI 0.31, 0.87). We concluded that any ACS was associated with reduced risks for neonatal early death and severe ROP among very preterm infants born to mothers with clinical chorioamnionitis.

Bronchopulmonary dysplasia in adults: Exploring pathogenesis and phenotype

This review highlights both the longstanding impact of bronchopulmonary dysplasia (BPD) on the health of adult survivors of prematurity and the pressing need for prospective, longitudinal studies of this population. Conservatively, there are an estimated 1,000,000 survivors of BPD in the United States alone. Unfortunately, most of the available literature regarding outcomes of lung disease due to prematurity naturally focuses on pediatric patients in early or middle childhood, and the relative amount of literature on adult survivors is scant. As the number of adult survivors of BPD continues to increase, it is essential that both adult and pediatric pulmonologists have a comprehensive understanding of the pathophysiology and underlying disease process, including the molecular signaling pathways and pro-inflammatory modulators that contribute to the pathogenesis of BPD. We summarize the most common presenting symptoms for adults with BPD and identify the critical challenges adult pulmonologists face in managing the care of survivors of prematurity. Specifically, these challenges include the wide variability of the clinical presentation of adult patients, comorbid cardiopulmonary complications, and the paucity of longitudinal data available on these patients. Adult survivors of BPD have even required lung transplantation, indicating the high burden of morbidity that can result from premature birth and subsequent lung injury. In addition, we analyze the disparate symptoms and management approach to adults with "old" BPD versus "new" BPD. The aim of this review is to assist pulmonologists in understanding the underlying pathophysiology of BPD and to improve clinical recognition of this increasingly common pulmonary disease.

Perinatal origins of bronchopulmonary dysplasia-deciphering normal and impaired lung development cell by cell

Bronchopulmonary dysplasia (BPD) is a multifactorial disease occurring as a consequence of premature birth, as well as antenatal and postnatal injury to the developing lung. BPD morbidity and severity depend on a complex interplay between prenatal and postnatal inflammation, mechanical ventilation, and oxygen therapy as well as associated prematurity-related complications. These initial hits result in ill-explored aberrant immune and reparative response, activation of pro-fibrotic and anti-angiogenic factors, which further perpetuate the injury. Histologically, the disease presents primarily by impaired lung development and an arrest in lung microvascular maturation. Consequently, BPD leads to respiratory complications beyond the neonatal period and may result in premature aging of the lung. While the numerous prenatal and postnatal stimuli contributing to BPD pathogenesis are relatively well known, the specific cell populations driving the injury, as well as underlying mechanisms are still not well understood. Recently, an effort to gain a more detailed insight into the cellular composition of the developing lung and its progenitor populations has unfold. Here, we provide an overview of the current knowledge regarding perinatal origin of BPD and discuss underlying mechanisms, as well as novel approaches to study the perturbed lung development.

The Role of Lung Function in Determining Which Children Develop Asthma

Longitudinal studies have demonstrated that altered indices of airway function, assessed shortly after birth, are a risk factor for the subsequent development of wheezing illnesses and asthma, and that these indices predict airway size and airway wall thickness in adult life. Pre- and postnatal factors that directly alter early airway function, such as extreme prematurity and cigarette smoke, may continue to affect airway function and, hence, the risks for wheeze and asthma. Early airway function and an associated asthma risk may also be indirectly influenced by immune system responses, respiratory viruses, the airway microbiome, genetics, and epigenetics, especially if they affect airway epithelial dysfunction. Few if any interventions, apart from smoking avoidance, have been proven to alter the risks of developing asthma, but vitamin C supplementation to pregnant smokers may help decrease the effects of in utero smoke on offspring lung function. We conclude that airway size and the factors influencing this play an important role in determining the risk for asthma across the lifetime. Progress in asthma prevention is long overdue and this may benefit from carefully designed interventions in well-phenotyped longitudinal birth cohorts with early airway function assessments monitored through to adulthood.

Alteration in branching morphogenesis via YAP/TAZ in fibroblasts of fetal lungs in an LPS-induced inflammation model

BACKGROUND

Chorioamnionitis is a common cause of preterm birth and leads to serious complications in newborns. The objective of this study was to investigate the role of the Hippo signaling pathway in lung branching morphogenesis under a lipopolysaccharide (LPS)-induced inflammation model.

MATERIALS AND METHODS

IMR-90 cells and ex vivo fetal lungs were treated with 0, 10, 30, or 50 μg/ml LPS for 24 and 72 h. Supernatant levels of lactate dehydrogenase (LDH), interleukin (IL)-6, IL-8, Chemokine (C-X-C motif) ligand 1(CXCL1), branching and the surface area ratio, Yes-associated protein (YAP), transcription coactivator with PDZ-binding motif (TAZ), fibroblast growth factor 10 (FGF10), fibroblast growth factor receptor II (FGFR2), SRY-box transcription factor 2 (SOX2), SOX9, and sirtuin 1 (SIRT1) levels were examined. Differentially expressed genes in fetal lungs after LPS treatment were identified by RNA-sequencing.

RESULTS

LPS at 50 μg/ml increased IL-6 and IL-8 in IMR-90 cells and increased IL-6, CXCL1 and LDH in fetal lungs. The branching ratio significantly increased by LPS at 30 μg/ml compared to the control but the increased level had decreased by 50 μg/ml LPS exposure. Exposure to 50 μg/ml LPS increased phosphorylated (p)-YAP, p-YAP/YAP, and p-TAZ/TAZ in IMR-90 cells, whereas 50 μg/ml LPS decreased FGF10 and SOX2. Consistently, p-YAP/YAP and p-TAZ/TAZ were increased in fibronectin⁺ cells of fetal lungs. Moreover, results of RNA-sequencing in fetal lungs showed that SMAD, FGF, IκB phosphorylation, tissue remodeling and homeostasis was involved in branching morphogenesis following exposure to 50 μg/ml LPS. The p-SIRT1/SIRT1 ratio increased in IMR-90 cells by LPS treatment.

CONCLUSIONS

This study showed that regulation of the Hippo pathway in fibroblasts of fetal lungs was involved in branching morphogenesis under an inflammatory disease such as chorioamnionitis.

The Relationship Between Cord Blood Cytokine Levels and Perinatal Characteristics and Bronchopulmonary Dysplasia: A Case-Control Study

Objective

To establish the association between serial levels of inflammatory cytokines in cord blood and perinatal characteristics and bronchopulmonary dysplasia (BPD) in preterm infants.

Methods

147 premature infants with gestational age ≤32 weeks who were born and hospitalized in the First Affiliated Hospital of Zhengzhou University between July 2019 and August 2021 were enrolled in this retrospective case-control study. Multiple microsphere flow immunofluorescence was used to detect seven cytokines in cord blood collected within 24 h of birth. Demographics, delivery characteristics, maternal factors, neonatal characteristics, and clinical outcomes were collected for the two groups. An unconditional logistic regression model was used in this study to assess the clinical variables.

Results

IL-6 cord blood levels at birth were significantly higher in the BPD group than in the non-BPD group, but the odds ratio (OR) was very small (OR = 1). No differences in other cytokine concentrations were observed between the two groups. Multivariable logistic regression analysis demonstrated that increased maternal white blood cell (WBC) count on admission and lower birth weight increased the risk of BPD progression.

Conclusions

Increased IL-6 cord blood levels at birth in preterm infants may have trivial significance for predicting BPD. Furthermore, higher maternal WBC count on admission and lower birth weight increased the risk of BPD.

A20 Is Increased in Fetal Lung in a Sheep LPS Model of Chorioamnionitis

Chorioamnionitis is associated with an increased risk of preterm birth and aggravates adverse outcomes such as BPD. Development of BPD is associated with chronic inflammatory reactions and oxidative stress in the airways which may be antenatally initiated by chorioamnionitis. A20 is an immunomodulatory protein involved in the negative feedback regulation of inflammatory reactions and is a possible regulator protein in oxidative stress reactions. The influence of chorioamnionitis on A20 gene regulation in the fetal lung is unknown. We characterized the influence of LPS and proinflammatory cytokines on A20 expression in human lung endothelial (HPMEC-ST1.6R) and epithelial (A549) cells in vitro by real-time PCR and/or western blotting and used a sheep model of LPS-induced chorioamnionitis for in vivo studies. To study the functional role of A20, endogenous A20 was overexpressed in HPMEC-ST1.6R and A549 cells. LPS induced proinflammatory cytokines in HPMEC-ST1.6R and A549 cells. Both LPS and/or proinflammatory cytokines elevated A20 at transcriptional and translational levels. Intra-amniotic LPS transiently increased IL-1β, IL-6, IL-8, and TNF-α mRNA levels in fetal lamb lungs, associated with an increase in A20 mRNA and protein levels. Overexpression of A20 reduced proinflammatory cytokines in vitro. Repeated LPS exposure induced LPS tolerance for proinflammatory cytokines and A20 in vitro and in vivo. Antenatal inflammation induced a transient increase in proinflammatory cytokines in the preterm fetal lung. The expression of proinflammatory cytokines increased expression of A20. Elevated A20 may have a protective role by downregulating chorioamnionitis-triggered fetal lung inflammation. A20 may be a novel target for pharmacological interventions to prevent chorioamnionitis-induced airway inflammation and lung damage, which can result in BPD later in life.

Amniotic fluid interleukin 6 and interleukin 8 are superior predictors of fetal lung injury compared with maternal or fetal plasma cytokines or placental histopathology in a nonhuman primate model

BACKGROUND

Intra-amniotic infection or inflammation is common in early preterm birth and associated with substantial neonatal lung morbidity owing to fetal exposure to proinflammatory cytokines and infectious organisms. Amniotic fluid interleukin 8, a proinflammatory cytokine, was previously correlated with the development of neonatal bronchopulmonary dysplasia, but whether amniotic fluid cytokines or placental pathology more accurately predicts neonatal lung pathology and morbidity is unknown. We have used a pregnant nonhuman primate model of group B Streptococcus infection to study the pathogenesis of intra-amniotic infection, bacterial invasion of the amniotic cavity and fetus, and microbial-host interactions. In this nonhuman primate model, we have studied the pathogenesis of group B Streptococcus strains with differing potential for virulence, which has resulted in a spectrum of intra-amniotic infection and fetal lung injury that affords the opportunity to study the inflammatory predictors of fetal lung pathology and injury.

OBJECTIVE

This study aimed to determine whether fetal lung injury is best predicted by placental histopathology or the cytokine response in amniotic fluid or maternal plasma.

STUDY DESIGN

Chronically catheterized pregnant monkeys (Macaca nemestrina, pigtail macaque) at 116 to 125 days gestation (term at 172 days) received a choriodecidual inoculation of saline (n=5), weakly hemolytic group B Streptococcus strain (n=5, low virulence), or hyperhemolytic group B Streptococcus strain (n=5, high virulence). Adverse pregnancy outcomes were defined as either preterm labor, microbial invasion of the amniotic cavity, or development of the fetal inflammatory response syndrome. Amniotic fluid and maternal and fetal plasma samples were collected after inoculation, and proinflammatory cytokines (tumor necrosis factor alpha, interleukin beta, interleukin 6, interleukin 8) were measured by a multiplex assay. Cesarean delivery was performed at the time of preterm labor or within 1 week of inoculation. Fetal necropsy was performed at the time of delivery. Placental pathology was scored in a blinded fashion by a pediatric pathologist, and fetal lung injury was determined by a semiquantitative score from histopathology evaluating inflammatory infiltrate, necrosis, tissue thickening, or collapse scored by a veterinary pathologist.

RESULTS

The principal findings in our study are as follows: (1) adverse pregnancy outcomes occurred more frequently in animals receiving hyperhemolytic group B Streptococcus (80% with preterm labor, 80% with fetal inflammatory response syndrome) than in animals receiving weakly hemolytic group B Streptococcus (40% with preterm labor, 20% with fetal inflammatory response syndrome) and in controls (0% preterm labor, 0% fetal inflammatory response syndrome); (2) despite differences in the rate of adverse pregnancy outcomes and fetal inflammatory response syndrome, fetal lung injury scores were similar between animals receiving the weakly hemolytic group B Streptococcus strains and animals receiving the hyperhemolytic group B Streptococcus strains; (3) fetal lung injury score was significantly correlated with peak amniotic fluid cytokines interleukin 6 and interleukin 8 but not tumor necrosis factor alpha or interleukin 1 beta; and (4) fetal lung scores were poorly correlated with maternal and fetal plasma cytokine levels and placental pathology.

CONCLUSION

Amniotic fluid interleukin 6 and interleukin 8 levels were superior predictors of fetal lung injury than placental histopathology or maternal plasma cytokines. This evidence supports a role for amniocentesis in the prediction of neonatal lung morbidity owing to intra-amniotic infection, which cannot be provided by cytokine analysis of maternal plasma or placental histopathology.

Pregnancy, Viral Infection, and COVID-19

Pregnancy comprises a unique immunological condition, to allow fetal development and to protect the host from pathogenic infections. Viral infections during pregnancy can disrupt immunological tolerance and may generate deleterious effects on the fetus. Despite these possible links between pregnancy and infection-induced morbidity, it is unclear how pregnancy interferes with maternal response to some viral pathogens. In this context, the novel coronavirus (SARS-CoV-2) can induce the coronavirus diseases-2019 (COVID-19) in pregnant women. The potential risk of vertical transmission is unclear, babies born from COVID-19-positive mothers seems to have no serious clinical symptoms, the possible mechanisms are discussed, which highlights that checking the children's outcome and more research is warranted. In this review, we investigate the reports concerning viral infections and COVID-19 during pregnancy, to establish a correlation and possible implications of COVID-19 during pregnancy and neonatal's health.

Foetal lung volumes in pregnant women who deliver very preterm: a pilot study

BACKGROUND

Infants born preterm are at increased risk of pulmonary morbidity. The contribution of antenatal factors to impairments in lung structure/function has not been fully elucidated. This study aimed to compare standardized lung volumes from foetuses that were delivered <32 weeks' gestation with foetuses that were delivered >37 weeks.

METHODS

Fourteen women who delivered <32 weeks gestation and 56 women who delivered >37 underwent a foetal MRI. Slice-volume reconstruction was then used and the foetal lungs were then segmented using multi-atlas approaches. Body volumes were calculated by manual segmentation and lung:body volume ratios generated.

RESULTS

Mean gestation at MRI of the preterm group was 27⁺² weeks (SD 2.9, range 20⁺⁶-31⁺³) and control group 25⁺³ weeks (SD 4.7 range 20⁺⁵-31⁺⁶). Mean gestation at delivery of the preterm group was 29⁺² weeks (SD 2.6, range 22⁺⁰-32⁺⁰). Lung:body volume ratios and foetal lung volumes were smaller in foetuses that were delivered preterm both with and without preterm premature rupture of membranes compared to those born at term (p < 0.001 in all cases).

CONCLUSIONS

Foetuses that were delivered very preterm had reduced lung volumes when standardized for foetal size, irrespective of ruptured membranes. These are novel findings and suggest an antenatal aetiology of insult and possible focus for future preventative therapies.

A Mother-to-Child Transmission Study in Nigeria: The Impact of Maternal HIV Infection and HAART on Plasma Immunoglobulins, Cytokine Profiles and Infant Outcome

Prevention of mother-to-child transmission (PMTCT) of HIV with highly active antiretroviral therapy (HARRT) allows the HIV⁺ pregnant mothers to have vaginal delivery and breastfeed. Here we investigated the maternal plasma immunoglobulin, cytokine secretion and the outcome of the exposed infants among the HIV⁺ HAART treated pregnant women in Nigeria. In this study, different plasma immunoglobulins and cytokines were measured in the HIV⁺ HAART treated pregnant mothers. Pooled culture supernatants of B and T lymphocytes showed lower levels of IFN-γ, IL-10 and IL-4. There were lower IFN-γ and IL-10 secretions at 1st trimester; however, IL-10 continued to be lower throughout 2nd and 3rd trimesters. TNF-α secretion significantly decreased as pregnancy progressed to term. There were high plasma IgG and low IgM in the HIV⁺ HAART treated pregnant women. Plasma IgG was high during 1st and 3rd trimesters. After one year of follow up, all the exposed children were seronegative for HIV-1 and HIV-2. Vaginal delivery and breastfeeding among HIV⁺ HAART treated mothers have shown to be safe. The use of HAART by the infected mothers and the use of septrin and niverapin by the exposed infants prevented mother to-child transmission of HIV.

Histological chorioamnionitis and risk of pulmonary complications in preterm births: a systematic review and Meta-analysis

Histological chorioamnionitis is associated with significant adverse maternal, perinatal and long-term outcome. We performed a meta-analysis of 30 observational studies in order to clarify the association between Histological chorioamnionitis and pulmonary complications, like respiratory distress syndrome and Bronchopulmonary Dysplasia. Unadjusted data extracted from all studies showed that Histological chorioamnionitis has no effect on development of RDS (RR 0.93, 95% CI 1.08-1.67), while it increased the risk of Bronchopulmonary Dysplasia (RR 1.75, 95% CI 1.37-2.23). However, when we restricted the analysis to the studies that adjust for Gestational Age, in order to exclude the influence of prematurity, we found that HCA reduced the risk of respiratory distress syndrome (RR 0.57, CI 95% 0.35-0.93) and it did not affect the development of Bronchopulmonary Dysplasia (RR 0.99, CI 0.76-1.3). Our results confirmed a possible role of prenatal inflammation on lung maturation. However, further prospective studies with a selected population are needed, in order to clarify the role of Histological chorioamnionitis in neonatal pulmonary complications.

An Unsettled Promise: The Newborn Piglet Model of Neonatal Acute Respiratory Distress Syndrome (NARDS). Physiologic Data and Systematic Review

Despite great advances in mechanical ventilation and surfactant administration for the newborn infant with life-threatening respiratory failure no specific therapies are currently established to tackle major pro-inflammatory pathways. The susceptibility of the newborn infant with neonatal acute respiratory distress syndrome (NARDS) to exogenous surfactant is linked with a suppression of most of the immunologic responses by the innate immune system, however, additional corticosteroids applied in any severe pediatric lung disease with inflammatory background do not reduce morbidity or mortality and may even cause harm. Thus, the neonatal piglet model of acute lung injury serves as an excellent model to study respiratory failure and is the preferred animal model for reasons of availability, body size, similarities of porcine and human lung, robustness, and costs. In addition, similarities to the human toll-like receptor 4, the existence of intraalveolar macrophages, the sensitivity to lipopolysaccharide, and the production of nitric oxide make the piglet indispensable in anti-inflammatory research. Here we present the physiologic and immunologic data of newborn piglets from three trials involving acute lung injury secondary to repeated airway lavage (and others), mechanical ventilation, and a specific anti-inflammatory intervention via the intratracheal route using surfactant as a carrier substance. The physiologic data from many organ systems of the newborn piglet—but with preference on the lung—are presented here differentiating between baseline data from the uninjured piglet, the impact of acute lung injury on various parameters (24 h), and the follow up data after 72 h of mechanical ventilation. Data from the control group and the intervention groups are listed separately or combined. A systematic review of the newborn piglet meconium aspiration model and the repeated airway lavage model is finally presented. While many studies assessed lung injury scores, leukocyte infiltration, and protein/cytokine concentrations in bronchoalveolar fluid, a systematic approach to tackle major upstream pro-inflammatory pathways of the innate immune system is still in the fledgling stages. For the sake of newborn infants with life-threatening NARDS the newborn piglet model still is an unsettled promise offering many options to conquer neonatal physiology/immunology and to establish potent treatment modalities.

Detrimental Effects of an Inhaled Phosphodiesterase-4 Inhibitor on Lung Inflammation in Ventilated Preterm Lambs Exposed to Chorioamnionitis Are Dose Dependent

Background: Treatment of bronchopulmonary dysplasia in preterm infants is challenging due to its multifactorial origin. In rodent models of neonatal lung injury, selective inhibition of phosphodiesterase 4 (PDE4) has been shown to exert anti-inflammatory properties in the lung. We hypothesized that GSK256066, a highly selective, inhalable PDE4 inhibitor, would have beneficial effects on lung injury and inflammation in a triple hit lamb model of Ureaplasma parvum (UP)-induced chorioamnionitis, prematurity, and mechanical ventilation. Methods: Twenty-one preterm lambs were surgically delivered preterm at 129 days after 7 days intrauterine exposure to UP. Sixteen animals were subsequently ventilated for 24 hours and received endotracheal surfactant and intravenous caffeine citrate. Ten animals were randomized to receive twice a high (10 μg/kg) or low dose (1 μg/kg) of nebulized PDE4 inhibitor. Results: Nebulization of high, but not low, doses of PDE4 inhibitor led to a significant decrease in pulmonary PDE activity, and was associated with lung injury and vasculitis, influx of neutrophils, and increased proinflammatory cytokine messenger RNA levels. Conclusion: Contrary to our hypothesis, we found in our model a dose-dependent proinflammatory effect of an inhaled highly selective PDE4 inhibitor in the lung. Our findings indicate the narrow therapeutic range of inhaled PDE4 inhibitors in the preterm population.

Developmentally Regulated Innate Immune NFκB Signaling Mediates IL-1α Expression in the Perinatal Murine Lung

Bronchopulmonary dysplasia (BPD) is the most common morbidity complicating premature birth. Importantly, preclinical models have demonstrated that IL-1 receptor antagonism prevents the lung injury and subsequent abnormal development that typically results following perinatal exposure to inflammatory stresses. This receptor is activated by two pro-inflammatory cytokines, IL-1α and IL-1β. While many studies have linked IL-1β to BPD development, IL-1α is relatively under-studied. The objective of our study was to determine whether systemic inflammatory stress induces IL-1α expression in the neonatal lung, and if so, whether this expression is mediated by innate immune NFκB signaling. We found that endotoxemia induced IL-1α expression during the saccular stage of neonatal lung development and was not present in the other neonatal organs or the adult lung. This IL-1α expression was dependent upon sustained pulmonary NFκB activation, which was specific to the neonatal lung. Using in vivo and in vitro approaches, we found that pharmacologic and genetic inhibition of NFκB signaling attenuated IL-1α expression. These findings demonstrate that innate immune regulation of IL-1α expression is developmentally regulated and occurs via an NFκB dependent mechanism. Importantly, the specific role of developmentally regulated pulmonary IL-1α expression remains unknown. Future studies must determine the effect of attenuating innate immune IL-1α expression in the developing lung before adopting broad IL-1 receptor antagonism as an approach to prevent neonatal lung injury.

The reduction in FOXA2 activity during lung development in fetuses from diabetic rat mothers is reversed by Akt inhibition

Hyperglycemia during pregnancy is associated with fetal lung development disorders and surfactant protein (SP) deficiency. Here, we examined the role of FOXA2 and Akt signaling in fetal lung development during diabetic pregnancy. Sprague‐Dawley rats were injected with streptozocin (STZ) during pregnancy to induce diabetes (DM). DM‐exposed fetal lungs exhibited reduced numbers of alveoli, irregularities in the appearance and thickness of the alveolar septum, increased levels of glycogen and lipids in type II alveolar epithelial cells, fewer microvilli and mature lamellar bodies, and swollen mitochondria. SP‐B and SP‐C in DM amniotic fluid and DM lungs were lower than in the control group (P < 0.05). DM lung nuclear FOXA2 was lower compared with the control group (P < 0.05), but p‐FOXA2 was higher (P < 0.05). In murine lung epithelial (MLE) 12 cells, p‐AKT levels were increased by high glucose/insulin, but decreased by the Akt inhibitor MK2206 (P < 0.05). Expression of nuclear FOXA2 was increased by MK2206 compared with the high glucose/insulin group (P < 0.05). These results suggest that maternal diabetes induces fetal lung FOXA2 phosphorylation through the Akt pathway, and also affects the maturation of alveolar epithelial cells and reduces levels of SP‐B and SP‐C in the fetal lungs. An Akt inhibitor reversed the changes in SP expression in vitro.

Impact of histologic chorioamnionitis on pulmonary hypertension and respiratory outcomes in preterm infants

We aimed to evaluate the association between the presence of histologic chorioamnionitis (HC) and development of pulmonary hypertension (PH) during neonatal intensive care unit (NICU) stay. Data of preterm infants born at 32 weeks of gestation or less were reviewed. The development of PH and other respiratory outcomes were compared according to the presence of HC. Potential risk factors associated with the development of PH during NICU stay were used for multivariable logistic regression analysis. A total of 188 infants were enrolled: 72 in the HC group and 116 in the no HC group. The HC group infants were born at a significantly shorter gestational age and lower birthweight, with a greater proportion presenting preterm premature rupture of membrane (pPROM) > 18 h before delivery. More infants in the HC group developed pneumothorax (P = 0.008), and moderate and severe bronchopulmonary dysplasia (BPD; P = 0.001 and P = 0.006, respectively). PH in the HC group was significantly more frequent compared to the no HC group (25.0% versus 8.6%, P = 0.002). Based on a multivariable logistic regression analysis, birthweight (P = 0.009, odds ratio [OR] = 0.997, 95% confidence interval [CI] = 0.995–0.999), the presence of HC (P = 0.047, OR = 2.799, 95% CI = 1.014–7.731), and duration of invasive mechanical ventilation (MV) > 14 days (P = 0.015, OR = 8.036, 95% CI = 1.051–43.030) were significant factors. The presence of HC and prolonged invasive MV in infants with lower birthweight possibly synergistically act against preterm pulmonary outcomes and leads to the development of PH. Verification of this result and further investigation to establish effective strategies to prevent or ameliorate these adverse outcomes are needed.

IKKβ Activation in the Fetal Lung Mesenchyme Alters Lung Vascular Development but Not Airway Morphogenesis

In the immature lung, inflammation and injury disrupt the epithelial-mesenchymal interactions required for normal development. Innate immune signaling and NF-κB activation disrupt the normal expression of multiple mesenchymal genes that play a key role in airway branching and alveolar formation. To test the role of the NF-κB pathway specifically in lung mesenchyme, we utilized the mesenchymal Twist2-Cre to drive expression of a constitutively active inhibitor of NF-κB kinase subunit β (IKKβca) mutant in developing mice. Embryonic Twist2-IKKβca mice were generated in expected numbers and appeared grossly normal. Airway branching also appeared normal in Twist2-IKKβca embryos, with airway morphometry, elastin staining, and saccular branching similar to those in control littermates. While Twist2-IKKβca lungs did not contain increased levels of Il1b, we did measure an increased expression of the chemokine-encoding gene Ccl2. Twist2-IKKβca lungs had increased staining for the vascular marker platelet endothelial cell adhesion molecule 1. In addition, type I alveolar epithelial differentiation appeared to be diminished in Twist2-IKKβca lungs. The normal airway branching and lack of Il1b expression may have been due to the inability of the Twist2-IKKβca transgene to induce inflammasome activity. While Twist2-IKKβca lungs had an increased number of macrophages, inflammasome expression remained restricted to macrophages without evidence of spontaneous inflammasome activity. These results emphasize the importance of cellular niche in considering how inflammatory signaling influences fetal lung development.

Human perinatal immunity in physiological conditions and during infection

The intrauterine environment was long considered sterile. However, several infectious threats are already present during fetal life. This review focuses on the postnatal immunological consequences of prenatal exposure to microorganisms and related inflammatory stimuli. Both the innate and adaptive immune systems of the fetus and neonate are immature, which makes them highly susceptible to infections. There is good evidence that prenatal infections are a primary cause of preterm births. Additionally, the association between antenatal inflammation and adverse neonatal outcomes has been well established. The lung, gastrointestinal tract, and skin are exposed to amniotic fluid during pregnancy and are probable targets of infection and subsequent inflammation during pregnancy. We found a large number of studies focusing on prenatal infection and the host response. Intrauterine infection and fetal immune responses are well studied, and we describe clinical data on cellular, cytokine, and humoral responses to different microbial challenges. The link to postnatal immunological effects including immune paralysis and/or excessive immune activation, however, turned out to be much more complicated. We found studies relating prenatal infectious or inflammatory hits to well-known neonatal diseases such as respiratory distress syndrome, bronchopulmonary dysplasia, and necrotizing enterocolitis. Despite these data, a direct link between prenatal hits and postnatal immunological outcome could not be undisputedly established. We did however identify several unresolved topics and propose questions for further research.

Surfactant phospholipid composition of gastric aspirate samples differs between male and female very preterm infants

BackgroundAmong preterm infants, males have a greater incidence of respiratory distress and death than do females born at the same gestational age, likely due to sex-related differences in lung maturation. Our aim was to determine whether surfactant phospholipid composition differs between male and female preterm infants.MethodsGastric aspirate samples from male and female infants born between 25 and 30 weeks of gestation at The Royal Women's Hospital, Melbourne, Australia, were collected within 1 h after birth. Phospholipid composition was analyzed by electrospray ionization tandem mass spectrometry.ResultsPreterm males had higher proportions of total phosphatidylinositol (PI) and phosphatidylserine 36:2, lower proportions of total sphingomyelin (S) and S 33:1 and 35:1, and a greater phosphatidylcholine (PC)/S ratio than did females. The proportions of PC 30:0, PC 34:0, PC 34:2, PC 36:2, PC 36:3, and PC 38:2 differed between the sexes at different gestational weeks of birth; the proportion of PC 32:0 (dipalmitoylphosphatidylcholine) in males was lower than that in females at 25 weeks of gestation but higher at 27 weeks.ConclusionPhospholipid composition in pulmonary surfactant is different between male and female preterm infants of the same gestational age, which may contribute to the increased risk for respiratory morbidities in one sex.

Prevalence and associated factors of diabetic retinopathy in Beijing, China: a cross-sectional study

OBJECTIVES

The study aimed to determine the exact risk factors for diabetic retinopathy (DR) in the Chinese population using a cohort of 17  985 individuals from Beijing, China.

DESIGN

Cross-sectional study.

SETTING

A hospital.

PARTICIPANTS

17  985 individuals from Beijing, China.

PRIMARY AND SECONDARY OUTCOME MEASURES

This was a cross-sectional study of permanent residents from the Changping area (Beijing, China) recruited from July 2010 to March 2011 and from March 2014 to February 2015 during a routine health examination at the Tongren Hospital of Beijing. Eye examinations were conducted by experienced ophthalmologists. Medical history, height, weight, body mass index (BMI) and blood pressure were recorded. Routine laboratory examinations were performed.

RESULTS

The prevalence of DR was 1.5% in the general study population and 8.1% among individuals with diabetes. Compared with the non-DR group, individuals in the DR group in the diabetes population had longer disease duration, higher systolic blood pressure (SBP), fasting plasma glucose (FPG) and uric acid (UA) (in men) and lower UA (in women) (all p<0.05). The multivariate analysis showed that disease duration (p<0.001), BMI (p=0.046), SBP (p=0.012), creatinine clearance rate (CCR) (p=0.014), UA (p=0.018) and FPG (p<0.001) were independently associated with DR in patients with diabetes.

CONCLUSION

The prevalence of DR was 8.1% among patients with diabetes. Disease duration, BMI, SBP, CCR, UA and FPG were independently associated with DR.

The Future of Bronchopulmonary Dysplasia: Emerging Pathophysiological Concepts and Potential New Avenues of Treatment

Yearly more than 15 million babies are born premature (<37 weeks gestational age), accounting for more than 1 in 10 births worldwide. Lung injury caused by maternal chorioamnionitis or preeclampsia, postnatal ventilation, hyperoxia, or inflammation can lead to the development of bronchopulmonary dysplasia (BPD), one of the most common adverse outcomes in these preterm neonates. BPD patients have an arrest in alveolar and microvascular development and more frequently develop asthma and early-onset emphysema as they age. Understanding how the alveoli develop, and repair, and regenerate after injury is critical for the development of therapies, as unfortunately there is still no cure for BPD. In this review, we aim to provide an overview of emerging new concepts in the understanding of perinatal lung development and injury from a molecular and cellular point of view and how this is paving the way for new therapeutic options to prevent or treat BPD, as well as a reflection on current treatment procedures.

Maternal serum cytokine levels in pregnancies complicated with threatened preterm labour

OBJECTIVE

To investigate serum inflammatory markers in singleton gestations complicated with threatened preterm labour (TPL).

METHODS

Pregnant women complicated with TPL (n = 61) were recruited to measure maternal serum levels of a panel of cytokines and C-reactive protein and then compared to controls without TPL, matched for gestational age (n = 64) and term pregnancies in the prodromal phase of labour (PPL) (n = 31). In addition, baseline cytokine levels were compared among cases and controls according to the outcome.

RESULTS

Women with TPL displayed higher CRP and white blood counts levels together with lower granulocyte macrophage colony-stimulating factor (GMC-SF) compared to both controls without TPL and to term gestations in the PPL. Also, interleukin 10 (IL-10), IL-6, IL-7, IL-8 and tumour necrosis alpha (TNF-α) levels were found significantly higher in TPL cases as compared to controls without TPL and term women in the PLL. Baseline cytokine levels (except IL-10) were higher among TPL cases who later delivered preterm. TPL cases delivering preterm displayed lower GMC-SF levels as compared to those delivering at term. Multivariate analysis found that gestational age at birth positively correlated with cervical length and inversely with CRP, IL-6 and TNF-α levels (p < 0.0001).

CONCLUSIONS

TPL and preterm birth were related to inflammatory changes in the maternal side that correlate with cervical shortening and the initiation of uterine contractions.

Caffeine modulates glucocorticoid-induced expression of CTGF in lung epithelial cells and fibroblasts

Background

Although caffeine and glucocorticoids are frequently used to treat chronic lung disease in preterm neonates, potential interactions are largely unknown. While anti-inflammatory effects of glucocorticoids are well defined, their impact on airway remodeling is less characterized. Caffeine has been ascribed to positive effects on airway inflammation as well as remodeling. Connective tissue growth factor (CTGF, CCN2) plays a key role in airway remodeling and has been implicated in the pathogenesis of chronic lung diseases such as bronchopulmonary dysplasia (BPD) in preterm infants. The current study addressed the impact of glucocorticoids on the regulation of CTGF in the presence of caffeine using human lung epithelial and fibroblast cells.

Methods

The human airway epithelial cell line H441 and the fetal lung fibroblast strain IMR-90 were exposed to different glucocorticoids (dexamethasone, budesonide, betamethasone, prednisolone, hydrocortisone) and caffeine. mRNA and protein expression of CTGF, TGF-β1-3, and TNF-α were determined by means of quantitative real-time PCR and immunoblotting. H441 cells were additionally treated with cAMP, the adenylyl cyclase activator forskolin, and the selective phosphodiesterase (PDE)-4 inhibitor cilomilast to mimic caffeine-mediated PDE inhibition.

Results

Treatment with different glucocorticoids (1 μM) significantly increased CTGF mRNA levels in H441 (p < 0.0001) and IMR-90 cells (p < 0.01). Upon simultaneous exposure to caffeine (10 mM), both glucocorticoid-induced mRNA and protein expression were significantly reduced in IMR-90 cells (p < 0.0001). Of note, 24 h exposure to caffeine alone significantly suppressed basal expression of CTGF mRNA and protein in IMR-90 cells. Caffeine-induced reduction of CTGF mRNA expression seemed to be independent of cAMP levels, adenylyl cyclase activation, or PDE-4 inhibition. While dexamethasone or caffeine treatment did not affect TGF-β1 mRNA in H441 cells, increased expression of TGF-β2 and TGF-β3 mRNA was detected upon exposure to dexamethasone or dexamethasone and caffeine, respectively. Moreover, caffeine increased TNF-α mRNA in H441 cells (6.5 ± 2.2-fold, p < 0.05) which has been described as potent inhibitor of CTGF expression.

Conclusions

In addition to well-known anti-inflammatory features, glucocorticoids may have adverse effects on long-term remodeling by TGF-β1-independent induction of CTGF in lung cells. Simultaneous treatment with caffeine may attenuate glucocorticoid-induced expression of CTGF, thereby promoting restoration of lung homeostasis.

Suggested Mechanisms of Tracheal Occlusion Mediated Accelerated Fetal Lung Growth: A Case for Heterogeneous Topological Zones

In this article, we report an up-to-date summary on tracheal occlusion (TO) as an approach to drive accelerated lung growth and strive to review the different maternal- and fetal-derived local and systemic signals and mechanisms that may play a significant biological role in lung growth and formation of heterogeneous topological zones following TO. Pulmonary hypoplasia is a condition whereby branching morphogenesis and embryonic pulmonary vascular development are globally affected and is classically seen in congenital diaphragmatic hernia. TO is an innovative approach aimed at driving accelerated lung growth in the most severe forms of diaphragmatic hernia and has been shown to result in improved neonatal outcomes. Currently, most research on mechanisms of TO-induced lung growth is focused on mechanical forces and is viewed from the perspective of homogeneous changes within the lung. We suggest that the key principle in understanding changes in fetal lungs after TO is taking into account formation of unique variable topological zones. Following TO, fetal lungs might temporarily look like a dynamically changing topologic mosaic with varying proliferation rates, dissimilar scale of vasculogenesis, diverse patterns of lung tissue damage, variable metabolic landscape, and different structures. The reasons for this dynamic topological mosaic pattern may include distinct degree of increased hydrostatic pressure in different parts of the lung, dissimilar degree of tissue stress/damage and responses to this damage, and incomparable patterns of altered lung zones with variable response to systemic maternal and fetal factors, among others. The local interaction between these factors and their accompanying processes in addition to the potential role of other systemic factors might lead to formation of a common vector of biological response unique to each zone. The study of the interaction between various networks formed after TO (action of mechanical forces, activation of mucosal mast cells, production and secretion of damage-associated molecular pattern substances, low-grade local pulmonary inflammation, and cardiac contraction-induced periodic agitation of lung tissue, among others) will bring us closer to an appreciation of the biological phenomenon of topological heterogeneity within the fetal lungs.

Can the preterm lung recover from perinatal stress?

After birth, adequate lung function is necessary for the successful adaptation of a preterm baby. Both prenatal and postnatal insults and therapeutic interventions have an immediate effect on lung function and gas exchange but also interfere with fetal and neonatal lung development. Prenatal insults like chorioamnionitis and prenatal interventions like maternal glucocorticosteroids interact but might also determine the preterm baby's lung response to postnatal interventions ("second hit") like supplementation of oxygen and drug therapy. We review current experimental and clinical findings on the influence of different perinatal factors on preterm lung development and discuss how well-established interventions in neonatal care might be adapted to attenuate postnatal lung injury.

IL-1β and Inflammasome Activity Link Inflammation to Abnormal Fetal Airway Development

Inflammation in the developing preterm lung leads to disrupted airway morphogenesis and chronic lung disease in human neonates. However, the molecular mechanisms linking inflammation and the pathways controlling airway morphogenesis remain unclear. In this article, we show that IL-1β released by activated fetal lung macrophages is the key inflammatory mediator that disrupts airway morphogenesis. In mouse lung explants, blocking IL-1β expression, posttranslational processing, and signaling protected the formation of new airways from the inhibitory effects ofEscherichia coliLPS. Consistent with a critical role for IL-1β, mice expressing a gain-of-functionNlrp3allele and subsequent overactive inflammasome activity displayed abnormal saccular-stage lung morphogenesis and died soon after birth. Although the early-stage fetal lung appeared capable of mounting an NF-κB-mediated immune response, airway formation became more sensitive to inflammation later in development. This period of susceptibility coincided with higher expression of multiple inflammasome components that could increase the ability to release bioactive IL-1β. Macrophages fromNlrp3gain-of-function mice also expressed higher levels of more mature cell surface markers, additionally linking inflammasome activation with macrophage maturation. These data identify developmental expression of the inflammasome and IL-1β release by fetal lung macrophages as key mechanisms and potential therapeutic targets for neonatal lung disease.

Meconium aspiration syndrome: a role for fetal systemic inflammation

BACKGROUND

Meconium aspiration syndrome (MAS) is a leading cause of morbidity and mortality in term infants. Meconium-stained amniotic fluid (MSAF) occurs in approximately 1 of every 7 pregnancies, but only 5% of neonates exposed to MSAF develop MAS. Why some infants exposed to meconium develop MAS while others do not is a fundamental question. Patients with MSAF have a higher frequency of intraamniotic inflammation/infection than those with clear fluid. We propose that fetal systemic inflammation is a risk factor for the development of MAS in patients with MSAF.

OBJECTIVE

We sought to investigate whether intraamniotic inflammation and funisitis, the histopathologic landmark of a fetal inflammatory response, predispose to MAS.

STUDY DESIGN

A prospective cohort study was conducted from 1995 through 2009. Amniotic fluid (AF) samples (n = 1281) were collected at the time of cesarean delivery from women who delivered singleton newborns at term (gestational age ≥38 weeks). Intraamniotic inflammation was diagnosed if the AF concentration of matrix metalloproteinase-8 was >23 ng/mL. Funisitis was diagnosed by histologic examination if inflammation was present in the umbilical cord.

RESULTS

The prevalence of MSAF was 9.2% (118/1281), and 10.2% (12/118) of neonates exposed to MSAF developed MAS. There were no significant differences in the median gestational age or umbilical cord arterial pH at birth between neonates who developed MAS and those who did not (each P > .1). Mothers whose newborns developed MAS had a higher median of AF matrix metalloproteinase-8 (456.8 vs 157.2 ng/mL, P < .05). Newborns exposed to intraamniotic inflammation had a higher rate of MAS than those who were not exposed to intraamniotic inflammation [13.0% (10/77) vs 0% (0/32), P = .03], as did those exposed to funisitis [31.3% (5/16) vs 7.3% (6/82); relative risk, 4.3; 95% confidence interval, 1.5-12.3]. Among the 89 newborns for whom both AF and placental histology were available, MAS was more common in patients with both intraamniotic inflammation and funisitis than in those without intraamniotic inflammation and funisitis [28.6% (4/14) vs 0% (0/28), P = .009], while the rate of MAS did not show a significant difference between patients with intraamniotic inflammation alone (without funisitis) and those without intraamniotic inflammation and funisitis [10.9% (5/46) vs 0% (0/28)].

CONCLUSION

The combination of intraamniotic inflammation with fetal systemic inflammation is an important antecedent of MAS. This concept has implications for the understanding of the mechanisms of disease responsible for MAS and for the development of prognostic models and therapeutic interventions for this disorder.

Effects of antenatal lipopolysaccharide and postnatal hyperoxia on airway reactivity and remodeling in a neonatal mouse model

BACKGROUND

Antenatal inflammation and preterm birth are associated with the development of airway diseases such as wheezing and asthma. Utilizing a newborn mouse model, we assessed the effects of maternal inflammation and postnatal hyperoxia on the neonatal airway.

METHODS

Pregnant C57/Bl6 dams were injected with lipopolysaccharide (LPS) or saline on embryonic day 16. Offspring were placed in room air or hyperoxia (50% O2) for 7 d and then returned to normoxia. Airway mechanics, histology, and laser capture micro-dissection (LCM) were performed.

RESULTS

At postnatal day 21, maternal LPS- and 50% O2-exposed pups exhibited increased resistance and decreased compliance compared to 21% O2 pups; however their effects were not synergistic. LPS and hyperoxia each increased the thickness of airway smooth muscle (ASM), but not the airway epithelial layer. Structural changes were largely limited to the conducting airways. Upregulation of inflammatory markers in the lung was observed at birth. LCM revealed increased collagen-3, transforming growth factor β, and connective tissue growth factor expression with LPS and hyperoxia within the ASM layer.

CONCLUSION

These novel studies provide functional, structural, and molecular evidence that antenatal inflammation is detrimental to the developing airway. Exposure to moderate hyperoxia does not exacerbate LPS effects on the airway.

Understanding the Impact of Infection, Inflammation, and Their Persistence in the Pathogenesis of Bronchopulmonary Dysplasia

The concerted interaction of genetic and environmental factors acts on the preterm human immature lung with inflammation being the common denominator leading to the multifactorial origin of the most common chronic lung disease in infants – ­bronchopulmonary dysplasia (BPD). Adverse perinatal exposure to infection/inflammation with added insults like invasive mecha nical ventilation, exposure to hyperoxia, and sepsis causes persistent immune dysregulation. In this review article, we have attempted to analyze and consolidate current knowledge about the role played by persistent prenatal and postnatal inflammation in the pathogenesis of BPD. While some parameters of the early inflammatory response (neutrophils, cytokines, etc.) may not be detectable after days to weeks of exposure to noxious stimuli, they have already initiated the signaling pathways of the inflammatory process/immune cascade and have affected permanent defects structurally and functionally in the BPD lungs. Hence, translational research aimed at prevention/amelioration of BPD needs to focus on dampening the inflammatory response at an early stage to prevent the cascade of events leading to lung injury with impaired healing resulting in the pathologic pulmonary phenotype of alveolar simplification and dysregulated vascularization characteristic of BPD.

Lung Disease, Oxidative Stress, and Oxygen Requirements in Preterm Infants

BACKGROUND

The role of oxidative stress remains unclear in the multifactorial pathophysiologic mechanism of lung disease in preterm infants.

AIMS

The aim of this study was to examine the associations among chronic lung disease (CLD), oxidative stress, and oxygen requirements in preterm infants.

DESIGN

Prospective, longitudinal, and correlational design.

SUBJECTS

Preterm infants born at <32 weeks' gestation (N = 31), median gestation of 29.0 weeks (range 24.9-31.7).

MEASUREMENTS

The diagnosis of CLD was obtained from the medical record. Oxidative stress was measured using 8-hydroxydeoxyguanosine (8-OHdG) in the cord blood at birth and urine on Days 1 and 7. Oxygen requirements were measured using fraction of inspired oxygen (FIO2) recorded in the first hour after birth/admission and the average FIO2 during the first 12 hr and 7 days after birth. Descriptive statistics are presented. Comparison analyses were performed using Kruskal-Wallis and Fisher's exact tests.

RESULTS

Infants with CLD (n = 12) had lower gestational age (p = .04) and weight (p = .04) at birth, more days on the ventilator (p = .004), and longer neonatal intensive care unit stay (p = .04) compared to infants without CLD (n = 19). CLD was associated with lower oxidative stress levels (p = .03) and higher oxygen requirements during the first 12 hr (p = .025) and on Day 7 (p = .001). Lower oxidative stress levels on Day 7 were associated with higher oxygen requirements in the first 12 hr (p = .01) and on Day 7 (p = .03).

CONCLUSION

Our results linking CLD and higher oxygen requirements with low oxidative stress contradict previous reports. Findings identify a gap in knowledge for postresuscitation oxygen therapy in preterm infants and expose the role of oxidative stress from inflammation and intermittent hypoxia in the etiology of CLD.

Maternal Asthma, Preterm Birth, and Risk of Bronchopulmonary Dysplasia

OBJECTIVE

To study the relationship between maternal asthma and the development of bronchopulmonary dysplasia (BPD).

STUDY DESIGN

Using a large population-based California cohort, we investigated associations between maternal asthma and preterm birth subtype, as well as maternal asthma and BPD. We used data from 2007-2010 maternal delivery discharge records of 2 009 511 pregnancies and International Classification of Diseases, Ninth Revision codes. Preterm birth was defined as <37 weeks gestational age (GA), with subgroups of <28 weeks, 28-32 weeks, and 33-37 weeks GA, as well as preterm subtype, defined as spontaneous, medically indicated, or unknown. Linkage between the 2 California-wide datasets yielded 21 944 singleton preterm infants linked to their mother's records, allowing estimation of the risk of BPD in mothers with asthma and those without asthma.

RESULTS

Maternal asthma was associated with increased odds (OR, 1.42; 95% CI, 1.38-1.46) of preterm birth at <37 weeks GA, with the greatest risk for 28-32 GA (aOR, 1.60; 95% CI, 1.47-1.74). Among 21 944 preterm infants, we did not observe an elevated risk for BPD in infants born to mothers with asthma (aOR, 1.03; 95% CI, 0.9-1.2). Stratification by maternal treatment with antenatal steroids revealed increased odds of BPD in infants whose mothers had asthma but did not receive antenatal steroids (aOR, 1.54; 95% CI, 1.15-2.06), but not in infants whose mothers had asthma and were treated with antenatal steroids (aOR, 0.85; 95% CI, 0.67-1.07).

CONCLUSION

Asthma in mothers who did not receive antenatal steroid treatment is associated with an increased risk of BPD in their preterm infants.

Recent advances in the mechanisms of lung alveolarization and the pathogenesis of bronchopulmonary dysplasia

Alveolarization is the process by which the alveoli, the principal gas exchange units of the lung, are formed. Along with the maturation of the pulmonary vasculature, alveolarization is the objective of late lung development. The terminal airspaces that were formed during early lung development are divided by the process of secondary septation, progressively generating an increasing number of alveoli that are of smaller size, which substantially increases the surface area over which gas exchange can take place. Disturbances to alveolarization occur in bronchopulmonary dysplasia (BPD), which can be complicated by perturbations to the pulmonary vasculature that are associated with the development of pulmonary hypertension. Disturbances to lung development may also occur in persistent pulmonary hypertension of the newborn in term newborn infants, as well as in patients with congenital diaphragmatic hernia. These disturbances can lead to the formation of lungs with fewer and larger alveoli and a dysmorphic pulmonary vasculature. Consequently, affected lungs exhibit a reduced capacity for gas exchange, with important implications for morbidity and mortality in the immediate postnatal period and respiratory health consequences that may persist into adulthood. It is the objective of this Perspectives article to update the reader about recent developments in our understanding of the molecular mechanisms of alveolarization and the pathogenesis of BPD.

Long-term pathological consequences of prenatal infection: beyond brain disorders

Prenatal immunological adversities such as maternal infection have been widely acknowledged to contribute to an increased risk of neurodevelopmental brain disorders. In recent years, epidemiological and experimental evidence has accumulated to suggest that prenatal exposure to immune challenges can also negatively affect various physiological and metabolic functions beyond those typically associated with primary defects in CNS development. These peripheral changes include excessive accumulation of adipose tissue and increased body weight, impaired glycemic regulation and insulin resistance, altered myeloid lineage development, increased gut permeability, hyperpurinergia, and changes in microbiota composition. Experimental work in animal models further suggests that at least some of these peripheral abnormalities could directly contribute to CNS dysfunctions, so that normalization of peripheral pathologies could lead to an amelioration of behavioral deficits. Hence, seemingly unrelated central and peripheral effects of prenatal infection could represent interrelated pathological entities that emerge in response to a common developmental stressor. Targeting peripheral abnormalities may thus represent a valuable strategy to improve the wide spectrum of behavioral abnormalities that can emerge in subjects with prenatal infection histories.

Inflammatory activity at school age in very low birth weight bronchopulmonary dysplasia survivors

OBJECTIVE

Airway inflammation is involved in the pathogenesis of bronchopulmonary dysplasia (BPD). The aim of the study was to evaluate the inflammatory activity in plasma and exhaled air in very low birth weight (VLBW) BPD survivors at school age.

METHODS

Twenty-one 6-14-year-old former VLBW (birth weight ≤1,500 g) children with severe radiographic BPD (radBPD), 19 without radBPD (nonBPD group) and 19 non-asthmatic term controls underwent measurement of eosinophil cationic protein, IL-6, IL-8, adiponectin, adipsin, leptin, and resistin in plasma, leukotriene B4 and 8-isoprostane in exhaled breath condensate, and NO in exhaled breath. Background data were obtained from patient records, clinical examination and parental questionnaire. Both univariate and multivariate models were applied in the statistical analysis.

RESULTS

There were no significant differences between the groups in any of the inflammatory markers measured. Five (25%) radBPD and 2 (11%) nonBPD children reported asthma (P = 0.058). In logistic regression analysis, exposure to chorioamnionitis was associated with low IL-8 (OR 29.0, 95% CI 3.27-258) and postnatal corticosteroid therapy with high adiponectin (OR 32.0, 95% CI 1.29-793). High body mass index standard deviation score (BMI-SDS) was associated with high plasma adipsin (OR 2.47, 95% CI 1.07-5.75) and leptin (OR 5.76, 95%CI 1.83-18.2) levels.

CONCLUSIONS

The inflammatory activity seems to decrease by school age in VLBW BPD survivors. Chorioamnionitis and postnatal corticosteroid treatment may modulate the inflammatory responsiveness in VLBW subjects even up to school age. The respiratory outcome in VLBW infants might be improved by preventing excessive weight gain.

Postnatal development and LPS responsiveness of pulmonary adenosine receptor expression and of adenosine-metabolizing enzymes in mice

BACKGROUND

Adenosine levels are regulated by ecto-5'-nucleotidase/CD73 and adenosine deaminase (ADA). Adenosine regulates endothelial permeability and anti-inflammatory responses via adenosine receptors. Here, the adenosine receptors and purine-converting enzymes were studied during postnatal development and inflammation.

METHODS

Newborn, 1-, 10-, 14-d-old and adult C57BL/6 mice were challenged intraperitoneally (i.p.) with lipopolysaccharide (LPS) for 6 h. The inflammatory response was evaluated by histochemistry. Expression levels of adenosine receptors (A1, A2A, A2B, and A3), CD73, and ADA were measured by quantitative reverse transcription polymerase chain reaction. A1 was studied by immunohistochemistry, and enzyme activities were analyzed by thin-layer chromatography.

RESULTS

LPS caused respiratory distress in newborns within 24 h. LPS induced neutrophils at the basal stage and alveolar congestion. Low activity and expression of CD73 increased after birth. Expression of ADA after LPS increased 16-fold in adults and 2-fold in newborns (P < 0.05). A1 expression was high in newborns and increased after LPS (P < 0.05). A1 was localized to endothelial membranes. A2A decreased after LPS in newborns and increased in adults (P < 0.05). The expression of A3 increased in newborns and adults after LPS.

CONCLUSION

Low pulmonary CD73 expression, LPS-induced suppression of A2A, LPS-induced increase of A1 expression, and severe respiratory distress were distinguishing responses in the newborns from those in the adults.

The effects of antenatal dietary and lifestyle advice for women who are overweight or obese on neonatal health outcomes: the LIMIT randomised trial

BACKGROUND

Overweight and obesity during pregnancy represents a considerable health burden. While research has focused on interventions to limit gestational weight gain, there is little information describing their impact on neonatal health. Our aim was to investigate the effect on a range of pre-specified secondary neonatal outcomes of providing antenatal dietary and lifestyle advice to women who are overweight or obese.

METHODS

We report a range of pre-specified secondary neonatal outcomes from a large randomised trial in which antenatal dietary and lifestyle advice was provided to women who were overweight or obese. Pregnant women were eligible for participation with a body mass index of 25 kg/m(2) or over, and singleton gestation between 10(+0) and 20(+0) weeks. Outcome measures included gestational age at birth; Apgar score below 7 at 5 minutes of age; need for resuscitation at birth; birth weight above 4.5 kg or below 2.5 kg; birth weight, length and head circumference (and Z-scores); admission to the nursery; respiratory distress syndrome; and postnatal length of stay. Data relating to the primary outcome (large for gestational age infants defined as birth weight above the 90th centile) and birth weight above 4 kg have been reported previously. Analyses used intention-to-treat principles.

RESULTS

In total, 2,142 infants were included in the analyses. Infants born to women following lifestyle advice were significantly less likely to have birth weight above 4.5 kg (2.15% versus 3.69%; adjusted risk ratio (aRR)=0.59; 95% confidence interval (CI) 0.36 to 0.98; P=0.04), or respiratory distress syndrome (1.22% versus 2.57%; aRR=0.47; 95% CI 0.24 to 0.90; P=0.02), particularly moderate or severe disease, and had a shorter length of postnatal hospital stay (3.94±7.26 days versus 4.41±9.87 days; adjusted ratio of means 0.89; 95% CI 0.82 to 0.97; P=0.006) compared with infants born to women who received Standard Care.

CONCLUSIONS

For women who are overweight or obese, antenatal dietary and lifestyle advice has health benefits for infants, without an increase in the risk of harm. Continued follow-up into childhood will be important to assess the longer-term effects of a reduction in high infant birth weight on risk of child obesity. Please see related articles: http://www.biomedcentral.com/1741-7015/12/161 and http://www.biomedcentral.com/1741-7015/12/201 .

CLINICAL TRIAL REGISTRATION

Australian and New Zealand Clinical Trials Registry ( ACTRN12607000161426 ).

Regulation of the Anti-Inflammatory Cytokines Interleukin-4 and Interleukin-10 during Pregnancy

Inflammation mediated by both innate and adaptive immune cells is necessary for several important processes during pregnancy. Pro-inflammatory immune cell activation plays a critical role in embryo implantation, placentation, and parturition; however dysregulation of these cells can lead to detrimental pregnancy outcomes including spontaneous abortion, fetal growth restriction, maternal pathology including hypertensive disorders, or fetal and maternal death. The resolution of inflammation plays an important role throughout pregnancy and is largely mediated by immune cells that produce interleukin (IL)-4 and IL-10. The temporal and spatial aspects of reducing inflammation during pregnancy represent a complex process that if not functioning optimally can lead to persistent inflammation and pregnancy complications. In this review, we examine how immune cells that produce IL-4 and IL-10 are regulated throughout pregnancy as well as the effects that reduced IL-4 and IL-10 signaling has on fetal and maternal physiology.

Caffeine and rolipram affect Smad signalling and TGF-β1 stimulated CTGF and transgelin expression in lung epithelial cells

Caffeine administration is an important part of the therapeutic treatment of bronchopulmonary dysplasia (BPD) in preterm infants. However, caffeine mediated effects on airway remodelling are still undefined. The TGF-β/Smad signalling pathway is one of the key pathways involved in airway remodelling. Connective tissue growth factor (CTGF), a downstream mediator of TGF-β, and transgelin, a binding and stabilising protein of the cytoskeleton, are both regulated by TGF-β1 and play an important role in airway remodelling. Both have also been implicated in the pathogenesis of BPD. The aim of the present study was to clarify whether caffeine, an unspecific phosphodiesterase (PDE) inhibitor, and rolipram, a prototypical PDE-4 selective inhibitor, were both able to affect TGF-β1-induced Smad signalling and CTGF/transgelin expression in lung epithelial cells. Furthermore, the effect of transgelin knock-down on Smad signalling was studied. The pharmacological effect of caffeine and rolipram on Smad signalling was investigated by means of a luciferase assay via transfection of a TGF-β1-inducible reporter plasmid in A549 cells. The regulation of CTGF and transgelin expression by caffeine and rolipram were studied by promoter analysis, real-time PCR and Western blot. Endogenous transgelin expression was down-regulated by lentiviral transduction mediating transgelin-specific shRNA expression. The addition of caffeine and rolipram inhibited TGF-β1 induced reporter gene activity in a concentration-related manner. They also antagonized the TGF-β1 induced up-regulation of CTGF and transgelin on the promoter-, the mRNA-, and the protein-level. Functional analysis showed that transgelin silencing reduced TGF-β1 induced Smad-signalling and CTGF induction in lung epithelial cells. The present study highlights possible new molecular mechanisms of caffeine and rolipram including an inhibition of Smad signalling and of TGF-β1 regulated genes involved in airway remodelling. An understanding of these mechanisms might help to explain the protective effects of caffeine in prevention of BPD and suggests rolipram to be a potent replacement for caffeine.

Systemic hydrogen sulfide administration partially restores normal alveolarization in an experimental animal model of bronchopulmonary dysplasia

Arrested alveolarization is the pathological hallmark of bronchopulmonary dysplasia (BPD), a complication of premature birth. Here, the impact of systemic application of hydrogen sulfide (H2S) on postnatal alveolarization was assessed in a mouse BPD model. Exposure of newborn mice to 85% O2 for 10 days reduced the total lung alveoli number by 56% and increased alveolar septal wall thickness by 29%, as assessed by state-of-the-art stereological analysis. Systemic application of H2S via the slow-release H2S donor GYY4137 for 10 days resulted in pronounced improvement in lung alveolarization in pups breathing 85% O2, compared with vehicle-treated littermates. Although without impact on lung oxidative status, systemic H2S blunted leukocyte infiltration into alveolar air spaces provoked by hyperoxia, and restored normal lung interleukin 10 levels that were otherwise depressed by 85% O2. Treatment of primary mouse alveolar type II (ATII) cells with the rapid-release H2S donor NaHS had no impact on cell viability; however, NaHS promoted ATII cell migration. Although exposure of ATII cells to 85% O2 caused dramatic changes in mRNA expression, exposure to either GYY4137 or NaHS had no impact on ATII cell mRNA expression, as assessed by microarray, suggesting that the effects observed were independent of changes in gene expression. The impact of NaHS on ATII cell migration was attenuated by glibenclamide, implicating ion channels, and was accompanied by activation of Akt, hinting at two possible mechanisms of H2S action. These data support further investigation of H2S as a candidate interventional strategy to limit the arrested alveolarization associated with BPD.

Lipopolysaccharide and soluble CD14 in cord blood plasma are associated with prematurity and chorioamnionitis

BACKGROUND

Lipopolysaccharide (LPS), an endotoxin of Gram-negative bacteria, causes preterm birth in animals and has been implicated as a factor triggering preterm labor and systemic complications in humans. Little is known regarding LPS in the cord blood (CB) of term and preterm infants and its association with maternal and fetal characteristics.

METHODS

CB was obtained from term (n = 15) and preterm infants (n = 76) after delivery. Plasma levels of LPS, C-reactive protein (CRP), and soluble CD14 (sCD14) were measured using commercially available kits (limulus amebocyte lysate and enzyme-linked immunosorbent assay). Four linear regression models were created in order to identify independent variables that predict plasma LPS levels.

RESULTS

The analyte levels were significantly higher in preterm vs. term infant CB: LPS (24.48 vs. 1 pg/ml; P = 0.0009), CRP (87.9 vs. 47 ng/ml; P = 0.01), and sCD14 (0.32 vs.0.35 µg/ml; P = 0.013). There was a (significant) positive correlation between CB LPS levels and gestational age, birth weight, CRP levels, sCD14 levels, and association with both clinical and histological chorioamnionitis.

CONCLUSION

Our data suggest that LPS is associated with preterm labor and inflammation (CRP elevation and chorioamnionitis). These findings may be relevant to the understanding of the role of LPS in prematurity and its role in preterm morbidities.

Changes in the inflammatory response to injury and its resolution during the loss of regenerative capacity in developing Xenopus limbs

Tissue and organ regeneration, unlike development, involves an injury that in postembryonic animals triggers inflammation followed by resolution. How inflammation affects epimorphic regeneration is largely uninvestigated. Here we examine inflammation and its resolution in Xenopus laevis hindlimb regeneration, which declines during larval development. During the first 5 days postamputation, both regeneration-competent stage 53 and regeneration-deficient stage 57 hindlimbs showed very rapid accumulation of leukocytes and cells expressing interleukin-1β and matrix metalloproteinase 9. Expression of genes for factors mediating inflammatory resolution appeared more persistent at stages 55 and 57 than at stage 53, suggesting changes in this process during development. FoxP3, a marker for regulatory T cells, was upregulated by amputation in limbs at all three stages but only persisted at stage 57, when it was also detected before amputation. Expression of genes for cellular reprogramming, such as SALL4, was upregulated in limbs at all 3 stages, but markers of limb patterning, such as Shh, were expressed later and less actively after amputation in regeneration-deficient limbs. Topical application of specific proinflammatory agents to freshly amputated limbs increased interleukin-1β expression locally. With aqueous solutions of the proinflammatory metal beryllium sulfate, this effect persisted through 7 days postamputation and was accompanied by inhibition of regeneration. In BeSO₄-treated limbs expression of markers for both inflammation and resolution, including FoxP3, was prolonged, while genes for cellular reprogramming were relatively unaffected and those for limb patterning failed to be expressed normally. These data imply that in Xenopus hindlimbs postamputation inflammation and its resolution change during development, with little effect on cellular dedifferentiation or reprogramming, but potentially interfering with the expression of genes required for blastema patterning. The results suggest that developmental changes in the larval anuran immune system may be involved in the ontogenetic loss of epimorphic regeneration in this system.

Influence of infection during pregnancy on fetal development

Infection by bacteria, viruses, and parasites may lead to fetal death, organ injury, or limited sequelae depending on the pathogen. Here, we consider the role of infection during pregnancy in fetal development including placental development and function, which can lead to fetal growth restriction. The classical group of teratogenic pathogens is referred to as 'TORCH' (Toxoplasma gondii, others like Treponema pallidum, rubella virus, cytomegalovirus, and herpes simplex virus) but should include a much broader group of pathogens including Parvovirus B19, Varicella zoster virus, and Plasmodium falciparum to name a few. In this review, we describe the influence of different infections in utero on fetal development and the short- and long-term outcomes for the neonate. In some cases, the mechanisms used by these pathogens to disrupt fetal development are well known. Bacterial infection of the developing fetal lungs and brain begins with an inflammatory cascade resulting in cytokine injury and oxidative stress. For some pathogens like P. falciparum, the mechanisms involve oxidative stress and apoptosis to disrupt placental and fetal growth. An in utero infection may also affect the long-term health of the infant; in many cases, a viral infection in utero increases the risk of developing type 1 diabetes in childhood. Understanding the varied mechanisms employed by these pathogens may enable therapies to attenuate changes in fetal development, decrease preterm birth, and improve survival.

Prenatal and childhood infections: implications for the development and treatment of childhood asthma

Bacterial and viral infections occur early and recurrently in life and thereby impose a substantial disease burden. Besides causing clinical symptoms, a potential role of infection in the development of the asthma syndrome later in life has also been suggested. However, whether bacterial and viral infections unmask host factors in children at risk of asthma or whether they directly cause asthma remains unclear; both viewpoints could be justified, but the underlying mechanisms are complex and poorly understood. Recently, the role of the bacterial microbiome has been emphasised. But data are still sparse and future studies are needed for definitive conclusions to be made. In this Review, we discuss present knowledge of viruses and bacteria that infect and colonise the respiratory tract and mucosal surfaces, including their timepoint of action, host factors related to infection, and their effect on childhood asthma. Childhood asthma could be the result of a combination of altered host susceptibility and infectious agents.