Risk factors for poorer respiratory outcomes in adolescents and young adults born preterm

Lung function outcomes in adults born extremely preterm across three decades of advancing perinatal medicine

AIM

Advances in perinatal medicine from 1980 to 2000 improved survival in extremely preterm (EP) neonates. Long-term effects of these developments remain unclear, and we aimed to investigate potential cohort effects on adult lung function.

METHODS

Three 18-year-old population-based cohorts born at ≤28 weeks gestation or with birthweight ≤1000 g during 1982-85, 1991-92 and 1999-2000 and term-controls underwent spirometry, body plethysmography, and tests of lung diffusing capacity, bronchodilator reversibility, and airway hyperresponsiveness. We used Welch's t-tests to compare term- with EP-born as a group and split by bronchopulmonary dysplasia (BPD), and regression models to test group/cohort interactions.

RESULTS

In all EP-born cohorts, z-scores for FEV1, FEV1/FVC, FEF25%-75%, DLCO and KCO were reduced compared with term-born. For the 82-85, 91-92 and 99-00 cohorts, deficits for z-FEV1 and z-DLCO were 1.23 and 0.53; 0.68 and 0.92; and 0.51 and 0.57, respectively (p ≤0.01 for all). Cohort analyses showed stable lung function across the three cohorts overall, but improvements across cohorts for the BPD subgroups in z-FEV1, z-FEV1/FVC, and z-FEF25%-75%.

CONCLUSION

Adults born EP across three formative decades of neonatal care had stable lung function overall, with notable improvements in BPD subgroups across cohorts.

Location-specific pathology analysis of monopodial airways in a rabbit model of bronchopulmonary dysplasia: a proof of principle study

BACKGROUND

The airways of the mammalian lung form a tree-like structure, starting from the trachea and branching out to the terminal bronchioles. This tree is composed of heterogeneous sub-structures or compartments, varying in morphological characteristics such as composition of airway epithelium, presence of cartilage plates, and number of smooth muscle cell layers or lumen diameter. These compartments may vary in their reaction to different pathological stimuli. Thus, when studying a particular lung disease, the compartments need to be investigated individually and not as part of a more global portmanteau compartment. In the symmetrically branching primate lungs, dividing the airway tree into generations is a common method to create morphologically homogeneous groups of airway segments. In common lab animals however, an asymmetrical branching pattern is present, where conventional branching-based grouping methods are unable to create meaningful results.

METHODS

Therefore, a morphological clustering approach was tested in the current proof of principle study for its suitability of dividing airways into biologically meaningful sub-compartments. On this basis, an investigation of the distribution of pulmonary airway changes in a bronchopulmonary dysplasia rabbit model was conducted.

RESULTS

The approach of clustering airway segments by morphology instead of branching pattern proved to be capable of creating meaningful airway compartments. This way, the distribution of differences that would not have been visible in a purely global comparison of morphological characteristics, could be identified between disease model and control group.

CONCLUSIONS

The employed clustering model is applicable to study the contribution of airway sub-compartments in pulmonary diseases. On this basis, targeted strategies for their mitigation may be developed.

Delayed airway epithelial repair is correlated with airway obstruction in young adults born very preterm

Nasal epithelial cells from young adults with a history of very preterm birth show delayed closure following scratch-wounding. Repair correlated with lung function, suggesting epithelial barrier integrity may play a role in preterm-associated lung disease. https://bit.ly/4dJnvWO.

Safety, Efficacy and Bio-Distribution Analysis of Exosomes Derived From Human Umbilical Cord Mesenchymal Stem Cells for Effective Treatment of Bronchopulmonary Dysplasia by Intranasal Administration in Mice Model

Purpose

Exosomes (Exos) derived from human umbilical cord mesenchymal stem cells (hUC-MSCs) hold great potential for treating bronchopulmonary dysplasia (BPD); however, safety concerns and effects of intranasal administration remain unexplored. This study aimed to explore the safety of hUC-MSCs and Exos and to investigate the efficacy and bio-distribution of repeated intranasal Exos administration in neonatal BPD models.

Methods

Characteristics of hUC-MSCs and Exos were analyzed. A subcutaneous tumor formation assay using a single dose of hUC-MSCs or Exos was conducted in Crl:NU-Foxn1nu mice. Vital signs, biochemical indices, pathological alterations, and 18F-FDG microPET/CT analysis were examined. Pulmonary pathology, three-dimensional reconstructions, ultrastructural structures, in vivo and ex vivo bio-distribution imaging analyses, enzyme-linked immunoassay assays, and reverse transcription-quantitative polymerase chain reaction analyses of lung tissues were all documented following intranasal Exos administration.

Results

Characteristics of hUC-MSCs and Exos satisfied specifications. Crl:NU-Foxn1nu mice did not exhibit overt toxicity or carcinogenicity following a single dose of hUC-MSCs or Exos after 60 days of observation. Repeated intranasal Exos administration effectively alleviated pathological injuries, restored pulmonary ventilation in three-dimensional reconstruction, and recovered endothelial cell layer integrity in ultrastructural analysis. Exos steadily accumulated in lung tissues from postnatal day 1 to 14. Exos also interrupted the epithelial-mesenchymal transition and inflammation reactions in BPD models.

Conclusion

As a nanoscale, non-cellular therapy, intranasal administration of Exos was an effective, noninvasive treatment for BPD. This approach was free from toxic, tumorigenic risks and repaired alveolar damage while interrupting epithelial-mesenchymal transition and inflammation in neonatal mice with BPD.

Research priorities for preterm lung health research across the lifespan: a community priority setting partnership

BACKGROUND

It is essential to embed patient and public perspectives into every stage of the research journey, including setting the future research agenda. The substantial gaps in our understanding of prematurity-associated lung disease presented a timely opportunity to determine the community's research priorities.

OBJECTIVE

To conduct a priority setting partnership (PSP) to determine the top 10 research priorities for preterm lung health.

DESIGN

We undertook a modified James Lind Alliance methodology comprising three main stages: (1) an idea generating survey with open questions to ascertain the community's most important ideas for future preterm lung health research, (2) prioritisation survey to distill the main themes into a shortlist of 20 and (3) consensus workshop where participants were tasked with ranking their final top 10. This PSP is reflective of the view of preterm-born individuals, parents of preterm children and healthcare professionals in an Australian healthcare setting.

RESULTS

We collated 144 submissions from the idea generating survey from which 27 prioritisation themes were developed. From the 150 prioritisation survey responses, the 20 themes receiving the most votes were taken to the consensus workshop. Participants identified the following top 10: (1) lifelong impacts; (2) interventions, treatments or supports; (3) ongoing lung health follow-up; (4) diagnostic tools, resources and education for primary healthcare providers; (5) resources to inform and empower families; (6) relationship to physical health and developmental issues; (7) preventing and/or treating lung infections; (8) additional supports, resources and research for minority groups; (9) impact on mental well-being; and (10) likelihood of asthma diagnosis.

CONCLUSION

Priorities identified through the PSP will be invaluable in informing future research into prematurity-associated lung disease.

Genetic score associations with birthweight in preterm-born infants compared with term-born infants

Objective

In preterm infants, lower birthweight correlates with a higher risk of neonatal complications. Understanding the factors influencing birthweight in these infants is important as it may guide future antenatal and perinatal care. Genetic variants account for at least one-quarter of variation in birthweight in term-born infants, but the genetic contribution to birthweight in preterm infants is not well understood. We aimed to compare genetic score associations with birthweight in a well-powered sample of preterm infants with those in term-born infants.

Study design

We used linear regression to test the association between birth weight and fetal genetic scores for birthweight (BW-GS) in a total of 1,416 preterm, singleton and 15,253 term, singleton infants. Analyses, adjusted for ancestry principal components were performed within each of 4 datasets and meta-analysed.

Results

In term-born infants: a 1 SD higher BW-GS was associated with a 1.20 (95% CI 1.10-1.29) SD higher birthweight. In preterm infants, there was also strong evidence of association, but with a smaller effect size (0.76SD (0.41-1.11) higher birthweight per 1-SD higher BW-GS). In preterms, when stratifying by gestational duration, we found that the associations strengthened with increasing gestational duration.

Conclusions

Genetic scores composed of variants identified in term-born infants also influenced birthweight in preterm infants. However, the associations had smaller effects in preterms and were weaker at earlier gestations. This suggests that while many of the same genetic factors influence birthweight in preterm and term-born infants, other factors (environmental, placental, different genetic) may be more important in preterms. Future well-powered studies are required to investigate this.

Anti-CCL2 therapy reduces oxygen toxicity to the immature lung

Oxygen toxicity constitutes a key contributor to bronchopulmonary dysplasia (BPD). Critical step in the pathogenesis of BPD is the inflammatory response in the immature lung with the release of pro-inflammatory cytokines and the influx of innate immune cells. Identification of efficient therapies to alleviate the inflammatory response remains an unmet research priority. First, we studied macrophage and neutrophil profiles in tracheal aspirates of n = 103 preterm infants <29 weeks´ gestation requiring mechanical ventilation. While no differences were present at birth, a higher fraction of macrophages, the predominance of the CD14+CD16+ subtype on day 5 of life was associated with moderate/severe BPD. Newborn CCL-2-/- mice insufficient in pulmonary macrophage recruitment had a reduced influx of neutrophils, lower apoptosis induction in the pulmonary tissue and better-preserved lung morphometry with higher counts of type II cells, mesenchymal stem cells and vascular endothelial cells when exposed to hyperoxia for 7 days. To study the benefit of a targeted approach to prevent the pulmonary influx of macrophages, wildtype mice were repeatedly treated with CCL-2 blocking antibodies while exposed to hyperoxia for 7 days. Congruent with the results in CCL-2-/- animals, the therapeutic intervention reduced the pulmonary inflammatory response, attenuated cell death in the lung tissue and better-preserved lung morphometry. Overall, our preclinical and clinical datasets document the predominant role of macrophage recruitment to the pathogenesis of BPD and establish the abrogation of CCL-2 function as novel approach to protect the immature lung from hyperoxic injury.

Prematurity-associated lung disease: is it asthma?

Not all wheeze is "asthma" in those born very preterm. Further work is needed to better understand the aetiology of prematurity-associated lung disease and the best treatments for this population. https://bit.ly/3Tko3vi.

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.

Early-life pulmonary viral infection leads to long-term functional and lower airway structural changes in the lungs

Early-life respiratory virus infections have been correlated with enhanced development of childhood asthma. In particular, significant numbers of respiratory syncytial virus (RSV)-hospitalized infants go on to develop lung disease. It has been suggested that early-life viral infections may lead to altered lung development or repair that negatively impacts lung function later in life. Our data demonstrate that early-life RSV infection modifies lung structure, leading to decreased lung function. At 5 wk postneonatal RSV infection, significant defects are observed in baseline pulmonary function test (PFT) parameters consistent with decreased lung function as well as enlarged alveolar spaces. Lung function changes in the early-life RSV-infected group continue at 3 mo of age. The altered PFT and structural changes induced by early-life RSV were mitigated in TSLPR-/- mice that have previously been shown to have reduced immune cell accumulation associated with a persistent Th2 environment. Importantly, long-term effects were demonstrated using a secondary RSV infection 3 mo following the initial early-life RSV infection and led to significant additional defects in lung function, with severe mucus deposition within the airways, and consolidation of the alveolar spaces. These studies suggest that early-life respiratory viral infection leads to alterations in lung structure/repair that predispose to diminished lung function later in life.NEW & NOTEWORTHY These studies outline a novel finding that early-life respiratory virus infection can alter lung structure and function long-term. Importantly, the data also indicate that there are critical links between inflammatory responses and subsequent events that produce a more severe pathogenic response later in life. The findings provide additional data to support that early-life infections during lung development can alter the trajectory of airway function.

Unravelling the respiratory health path across the lifespan for survivors of preterm birth

Many survivors of preterm birth will have abnormal lung development, reduced peak lung function and, potentially, an increased rate of physiological lung function decline, each of which places them at increased risk of chronic obstructive pulmonary disease across the lifespan. Current rates of preterm birth indicate that by the year 2040, around 50 years since the introduction of surfactant therapy, more than 700 million individuals will have been born prematurely-a number that will continue to increase by about 15 million annually. In this Personal View, we describe current understanding of the impact of preterm birth on lung function through the life course, with the aim of putting this emerging health crisis on the radar for the respiratory community. We detail the potential underlying mechanisms of prematurity-associated lung disease and review current approaches to prevention and management. Furthermore, we propose a novel way of considering lung disease after preterm birth, using a multidimensional model to determine individual phenotypes of lung disease-a first step towards optimising management approaches for prematurity-associated lung disease.