Mechanism of lung development in the aetiology of adult congenital pulmonary airway malformations

Prenatal Array-CGH Detection of 3q26.32q26.33 Interstitial Deletion Encompassing the SOX2 Gene: Ultrasound, Pathological, and Cytogenetic Findings

Background: SOX2 disorders are associated with anophthalmia-esophageal-genital syndrome or microphthalmia, syndromic 3 (MCOPS3- # 206900). Case Report: We describe a third fetal case with a de novo 3q26.32q26.33 deletion extending for 4.31 Mb, detected in a 15-week fetus. After legal interruption of pregnancy, at autopsy, the fetus presented bilateral microphthalmia, right cleft lip and palate, bilateral cerebral ventriculomegaly and dilated third ventricle, microcystic left lung, and intestinal malrotation. Histologically, the left lung showed congenital pulmonary airway malformation (CPAM) type 2. Retinal dysplasia was found in both eyes. Discussion/Conclusion: The human SOX2 gene (OMIM #184429) is located on chromosome 3 at position q26.3-27 and encodes a transcription factor involved in the development of the central and peripheral nervous systems, retina, and lung. In our case, the combination of cerebral, retinal, and pulmonary anomalies, not previously described, are consistent with SOX2 haploinsufficiency due to chromosomal deletion.

Congenital lung malformations

Congenital lung malformations (CLMs) are rare developmental anomalies of the lung, including congenital pulmonary airway malformations (CPAM), bronchopulmonary sequestration, congenital lobar overinflation, bronchogenic cyst and isolated congenital bronchial atresia. CLMs occur in 4 out of 10,000 live births. Postnatal presentation ranges from an asymptomatic infant to respiratory failure. CLMs are typically diagnosed with antenatal ultrasonography and confirmed by chest CT angiography in the first few months of life. Although surgical treatment is the gold standard for symptomatic CLMs, a consensus on asymptomatic cases has not been reached. Resection, either thoracoscopically or through thoracotomy, minimizes the risk of local morbidity, including recurrent infections and pneumothorax, and avoids the risk of malignancies that have been associated with CPAM, bronchopulmonary sequestration and bronchogenic cyst. However, some surgeons suggest expectant management as the incidence of adverse outcomes, including malignancy, remains unknown. In either case, a planned follow-up and a proper transition to adult care are needed. The biological mechanisms through which some CLMs may trigger malignant transformation are under investigation. KRAS has already been confirmed to be somatically mutated in CPAM and other genetic susceptibilities linked to tumour development have been explored. By summarizing current progress in CLM diagnosis, management and molecular understanding we hope to highlight open questions that require urgent attention.

Congenital lung malformations: Dysregulated lung developmental processes and altered signaling pathways

Congenital lung malformations comprise a diverse group of anomalies including congenital pulmonary airway malformation (CPAM, previously known as congenital cystic adenomatoid malformation or CCAM), bronchopulmonary sequestration (BPS), congenital lobar emphysema (CLE), bronchogenic cysts, and hybrid lesions. Little is known about the signaling pathways that underlie the pathophysiology of these lesions and the processes that may promote their malignant transformation. In the last decade, the use of transgenic/knockout animal models and the implementation of next generation sequencing on surgical lung specimens have increased our knowledge on the pathophysiology of these lesions. Herein, we provide an overview of normal lung development in humans and rodents, and we discuss the current state of knowledge on the pathophysiology and molecular pathways that are altered in each congenital lung malformation.

Transcriptome analysis of lncRNA expression patterns in human congenital lung malformations

Objectives

To explore the long non-coding RNA (lncRNA) expression pattern of congenital lung malformations on a genome-wide scale and investigate their potential biological function in four subtypes of congenital lung malformations.

Methods

We obtained both lesions and normal lung control tissues from the patients diagnosed with CPAM-I, CPAM-II, ILS, and ILS-CPAM, and underwent lobectomy (i.e., surgical removal of the whole lobe which contains the localized lesion as well as normal lung tissue). Then, we performed lncRNA transcriptome profiling in these tissues by RNA sequencing (RNA-seq). A comprehensive bioinformatics analysis was conducted to characterize the expression profiles and relevant biological functions and for multiple comparisons of lncRNA expression in the different subtypes of congenital lung malformation tissues. Furthermore, the lncRNA-mRNA co-expression network was constructed, and dysregulated mRNAs were functionally analyzed. Finally, gene set enrichment analysis (GSEA) was used to predict the potential molecular mechanism of the identified lncRNAs.

Results

A total of 5921 lncRNA transcripts were identified between congenital lung malformations tissues and normal lung control tissues. Compared with normal lung control, 481of these expressed lncRNAs were upregulated and 142 were downregulated in CPAM-I, 91 were upregulated and 14 were downregulated in CPAM-II, 39 were upregulated and 38 were downregulated in ILS, and 201 were upregulated and 38 were downregulated in ILS-CPAM. Unsupervised clustering and principal component analysis of the expressed lncRNAs visualized the differences between normal lung control and different subtypes of congenital lung malformations samples. We also confirmed significant differences in the composition of differentially expressed genes (DEGs) and the differentially expressed lncRNAs (DE lncRNAs) between CPAM-I and other subtypes of congenital lung malformations, as well as in normal lung control tissues, and observed enrichment of DEGs in the regulation of the immune system, cell projection organization, and inflammatory pathways. Finally, we identified the lncRNA FLJ26850 might be related to congenital lung malformations via ZNF473.

Conclusions

Significant differences in lncRNAs expression patterns were observed between different subtypes of congenital lung malformations and normal control. The lncRNA FLJ26850 might be related to congenital lung malformations via ZNF473.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-08204-x.

Developmental Pathways Underlying Lung Development and Congenital Lung Disorders

Lung organogenesis is a highly coordinated process governed by a network of conserved signaling pathways that ultimately control patterning, growth, and differentiation. This rigorously regulated developmental process culminates with the formation of a fully functional organ. Conversely, failure to correctly regulate this intricate series of events results in severe abnormalities that may compromise postnatal survival or affect/disrupt lung function through early life and adulthood. Conditions like congenital pulmonary airway malformation, bronchopulmonary sequestration, bronchogenic cysts, and congenital diaphragmatic hernia display unique forms of lung abnormalities. The etiology of these disorders is not yet completely understood; however, specific developmental pathways have already been reported as deregulated. In this sense, this review focuses on the molecular mechanisms that contribute to normal/abnormal lung growth and development and their impact on postnatal survival.

Pleuropulmonary blastoma, a rare entity in childhood

Pleuropulmonary blastoma (PPB) is a rare malignant intrathoracic mesenchymal tumour with a variable aggressiveness. It is the most common primary malignancy in the lung during childhood. In this study, we present a case of a 3-year-old male child who complained of persistent dry cough. Radiographs suggested the diagnosis of PPB, which was been confirmed by the histo-pathological examination of a biopsy taken from the tumour under CT guidance. This case was reported to emphasise the importance of radiology, whether diagnotic or interventional, in diagnosing rare cases such as PPB.