Diffuse lung disease in children: summary of a scientific conference

A method of generating alveolar organoids using human pluripotent stem cells

The lung consists of branched structures that are anatomically, developmentally and functionally divided into airway and alveolar regions. Each region contributes to lung-specific functions involving a defense system and gas exchange, and their dysfunction can cause fatal lung diseases. In the alveolar region, the cuboidal alveolar type 2 (AT2) cells account for 90% of the alveolar epithelial cells and serve as the tissue stem cells secreting pulmonary surfactant, and flattened alveolar type I (AT1) cells cover most of the alveolar surface directly contributing to gas exchange adjacent to capillary vessels. It has been difficult to culture alveolar epithelial cells in vitro, as the lineage-specific features of those cells are rapidly lost in a conventional two-dimensional culture setting. The culture of alveolar organoids (AOs) is an emerging technique that can help maintain the features of alveolar epithelial cells in vitro, and their application to human disease modeling is eagerly awaited. We herein describe our method of generating and culturing alveolar epithelial cells and AOs derived from human induced pluripotent stem cells (iPSCs). iPSCs derived from lung disease patients, including those with rare genetic diseases, will make help elucidate the disease mechanism and hopefully identify therapeutic targets.

Genomics, microbiomics, proteomics, and metabolomics in bronchopulmonary dysplasia

Bronchopulmonary Dysplasia (BPD) is a disorder with a multifactorial etiology and highly variable clinical phenotype. Several traditional biomarkers have been identified, but due to the complex disease phenotype, these biomarkers have low predictive accuracy for BPD. In recent years, newer technologies have facilitated the in-depth and unbiased analysis of 'big data' in delineating the diagnosis, pathogenesis, and mechanisms of diseases. Novel systems-biology based 'omic' approaches, including but not limited to genomics, microbiomics, proteomics, and metabolomics may help define the multiple cellular and humoral interactions that regulate normal as well as abnormal lung development and response to injury that are the hallmarks of BPD.

The proteomics of lung injury in childhood: challenges and opportunities

Proteomics, the large-scale study of the structure and function of proteins of a cell or organism, is a rapidly developing area of biomedical research which is perfectly suited to the study of pediatric lung injury, where a variety of samples are easily, and repeatedly, accessible including plasma (reflecting a whole body response) and broncheoalveolar lung fluid (reflecting the lungs response). When applied to pediatric lung injury, proteomics could be used to develop much needed early biomarkers of lung injury, elucidate pathological pathways and determine protein alterations associated with specific disease processes. However despite the obvious benefits and need, proteomics is rarely utilized in studies of pediatric injury. This review primarily reports on the last decade of pediatric research into proteomes associated with specific respiratory diseases including bronchopulmonary dysplasia, respiratory infection, cystic fibrosis and asthma whilst also reflecting on the challenges unique to proteomic studies of the pediatric respiratory disease population. We conclude that the number of key pathological differences between the pediatric and adult study populations inhibit inference of results from adult studies onto a pediatric population and necessitate studies of the pediatric proteome. Furthermore the disparity amongst pediatric lung disease in terms of age at onset and underlying pathological mechanism (genetic, immunological, intervention-based, developmental arrest, inhaled toxin) will require proteomic studies which are well designed, with large disease specific patient sets to ensure adequate power as well as matched controls. Regardless of causative agent, pulmonary biomarkers are needed to predict the clinical course of pediatric lung disease, status, progression and response to treatment. Identification of early biomarkers is particularly pertinent in order to understand the natural history of disease and monitor progression so prevention of ongoing lung injury and impact on childhood can targeted.

Pediatric Pulmonology year in review 2014: Part 1

Our discipline and our journal cover an extremely broad range of research and scholarly topics related to children's respiratory disorders. To better meet the needs of our readership for updated perspectives on the rapidly expanding knowledge in our field, we here summarize the past year's publications in our major topic areas, as well as selected publications in these areas from the core clinical journal literature outside our own pages.

Beyond the genome: epigenetic mechanisms in lung remodeling

The lung develops from a very simple outpouching of the foregut into a highly complex, finely structured organ with multiple specialized cell types that are required for its normal physiological function. During both the development of the lung and its remodeling in the context of disease or response to injury, gene expression must be activated and silenced in a coordinated manner to achieve the tremendous phenotypic heterogeneity of cell types required for homeostasis and pathogenesis. Epigenetic mechanisms, consisting of DNA base modifications such as methylation, alteration of histones resulting in chromatin modification, and the action of noncoding RNA, control the regulation of information "beyond the genome" required for both lung modeling and remodeling. Epigenetic regulation is subject to modification by environmental stimuli, such as oxidative stress, infection, and aging, and is thus critically important in chronic remodeling disorders such as idiopathic pulmonary fibrosis (IPF), chronic obstructive pulmonary disease (COPD), bronchopulmonary dysplasia (BPD), and pulmonary hypertension (PH). Technological advances have made it possible to evaluate genome-wide epigenetic changes (epigenomics) in diseases of lung remodeling, clarifying existing pathophysiological paradigms and uncovering novel mechanisms of disease. Many of these represent new therapeutic targets. Advances in epigenomic technology will accelerate our understanding of lung development and remodeling, and lead to novel treatments for chronic lung diseases.

Epigenetic contributions to the developmental origins of adult lung disease

Perinatal insults, including intrauterine growth restriction, preterm birth, maternal exposure to toxins, or dietary deficiencies produce deviations in the epigenome of lung cells. Occurrence of perinatal insults often coincides with the final stages of lung development. The result of epigenome disruptions in response to perinatal insults during lung development may be long-term structural and functional impairment of the lung and development of lung disease. Understanding the contribution of epigenetic mechanisms to life-long lung disease following perinatal insults is the focus of the developmental origins of adult lung disease field. DNA methylation, histone modifications, and microRNA changes are all observed in various forms of lung disease. However, the perinatal contribution to such epigenetic mechanisms is poorly understood. Here we discuss the developmental origins of adult lung disease, the interplay between perinatal events, lung development and disease, and the role that epigenetic mechanisms play in connecting these events.

Pediatric lung transplantation: indications and outcomes

Lung transplantation (LTx) is a treatment option for infants and children with untreatable and otherwise fatal pulmonary diseases. To date, over 1,800 lung transplants have been performed, most frequently in children over the age of five years. The most common indications for transplantation in children overall are cystic fibrosis (CF) and idiopathic pulmonary hypertension (PH). The surfactant protein deficiencies, other interstitial lung diseases (ILDs), and congenital heart disease are important indications among young children and infants. Re-transplantation is an option for selected recipients with chronic allograft rejection. Overall survival following pediatric LTx is similar to that encountered in adult patients, with recent registry data indicating a median survival of 4.9 years. Other outcomes such as the incidence of bronchiolitis obliterans (BO) and the presence of key post-transplant co-morbid conditions are also similar to the experience in adult lung transplant recipients.