NKX2‐1 (NK2 homeobox 1) is a critical regulator of transcription for the surfactant protein (SP)‐B and ‐C genes (SFTPB and SFTPC, respectively). We identified and functionally characterized two new de novo NKX2‐1 mutations c.493C>T (p.R165W) and c.786_787del2 (p.L263fs) in infants with closely similar severe interstitial lung disease (ILD), hypotonia, and congenital hypothyroidism. Functional analyses using A549 and HeLa cells revealed that NKX2‐1‐p.L263fs induced neither SFTPB nor SFTPC promoter activation and had a dominant negative effect on wild‐type (WT) NKX2‐1. In contrast,NKX2‐1‐p.R165W activated SFTPC, to a significantly greater extent than did WTNKX2‐1,whileSFTPB activation was only significantly reduced in HeLa cells. In accordance with our in vitro data, we found decreased amounts of SP‐B and SP‐C by western blot in bronchoalveolar lavage fluid (patient with p.L263fs) and features of altered surfactant protein metabolism on lung histology (patient with NKX2‐1‐p.R165W). In conclusion, ILD in patients with NKX2‐1 mutations was associated with altered surfactant protein metabolism, and both gain and loss of function of the mutated NKX2‐1 genes on surfactant protein promoters were associated with ILD in “Brain‐Lung‐Thyroid syndrome”.

Interstitial lung disease (ILD) in infants and children comprises a large spectrum of rare respiratory disorders that are mostly chronic and associated with high morbidity and mortality. These disorders are characterized by inflammatory and fibrotic changes that affect alveolar walls. Typical features of ILD include dyspnea, diffuse infiltrates on chest radiographs, and abnormal pulmonary function tests with restrictive ventilatory defect and/or impaired gas exchange. Many pathological situations can impair gas exchange and, therefore, may contribute to progressive lung damage and ILD. Consequently, diagnosis approach needs to be structured with a clinical evaluation requiring a careful history paying attention to exposures and systemic diseases. Several classifications for ILD have been proposed but none is entirely satisfactory especially in children. The present article reviews current concepts of pathophysiological mechanisms, etiology and diagnostic approaches, as well as therapeutic strategies. The following diagnostic grouping is used to discuss the various causes of pediatric ILD: 1) exposure-related ILD; 2) systemic disease-associated ILD; 3) alveolar structure disorder-associated ILD; and 4) ILD specific to infancy. Therapeutic options include mainly anti-inflammatory, immunosuppressive, and/or anti-fibrotic drugs. The outcome is highly variable with a mortality rate around 15%. An overall favorable response to corticosteroid therapy is observed in around 50% of cases, often associated with sequelae such as limited exercise tolerance or the need for long-term oxygen therapy.

Background: Idiopathic pulmonary hemosiderosis (IPH) is a rare cause of alveolar hemorrhage in children and its pathophysiology remains obscure. Classically, diagnosis is based on a triad including hemoptysis, diffuse parenchymal infiltrates on chest X-rays, and iron-deficiency anemia. We present the French pediatric cohort of IPH collected through the French Reference Center for Rare Lung Diseases (RespiRare®,http://www.respirare.fr).Methods: Since 2008, a national network/web-linked RespiRare® database has been set up in 12 French pediatric respiratory centres. It is structured as a medical recording tool with extended disease-specific datasets containing clinical information relevant to all forms of rare lung diseases including IPH.Results: We identified 25 reported cases of IPH in children from the database (20 females and 5 males). Among them, 5 presented with Down syndrome. Upon diagnosis, median age was 4.3 [0.8-14.0] yrs, and the main manifestations were: dyspnea (n = 17, 68%), anemia (n = 16, 64%), cough (n = 12, 48%), febrile pneumonia (n = 11, 44%) and hemoptysis (n = 11, 44%). Half of the patients demonstrated diffuse parenchymal infiltrates on chest imaging, and diagnosis was ascertained either by broncho-alveolar lavage indicating the presence of hemosiderin-laden macrophages (19/25 cases), or lung biopsy (6/25). In screened patients, initial auto-immune screening revealed positive antineutrophilic cytoplasmic antibodies (ANCA) (n = 6, 40%), antinuclear antibodies (ANA) (n = 5, 45%) and specific coeliac disease antibodies (n = 4, 28%). All the patients were initially treated by corticosteroids. In 13 cases, immunosuppressants were introduced due to corticoresistance and/or major side effects. Median length of follow-up was 5.5 yrs, with a satisfactory respiratory outcome in 23/25 patients. One patient developed severe pulmonary fibrosis, and another with Down syndrome died as a result of severe pulmonary hemorrhage.Conclusion: The present cohort provides substantial information on clinical expression and outcomes of pediatric IPH. Analysis of potential contributors supports a role of auto-immunity in disease development and highlights the importance of genetic factors.

Introduction: COVID‐19 pandemic and associated lockdown measures have deeply modified the natural course of seasonal viral infections, such as respiratory syncytial virus (RSV).Methods: We analyzed French national data from three networks: emergency departments (ED) of French hospitals, general practitioners (GP), and hospital laboratories. We compared the number of ED or GP visits for bronchiolitis in children <2 years of age, and the percentage of RSV positive tests in the 2020 to 2021 season with those of the two previous seasons (2018–2019 and 2019–2020). We used time series of the previous 5 years to calculate epidemic thresholds.Results: During the 2020–2021 season, the epidemic begun in February (Week 05) in the Ile de France (Paris and suburbs) region, 12 weeks later compared with the previous seasons and progressively spread across all the French metropolitan regions. The highest number of bronchiolitis cases in 2021 (Week 12) occurred 10–12 weeks after the previous seasonal peaks of previous seasons, but the number of cases remained lower than in the previous seasonal peaks.Conclusion: We identified a delayed RSV epidemic in the period that usually corresponds at the end of the epidemic season, raising concerns for the burden of RSV in the already strained healthcare systems during the COVID‐19 pandemic.

Interstitial lung diseases (ILDs) in children represent a heterogeneous group of rare respiratory disorders that affect the lung parenchyma. After the launch of the French Reference Centre for Rare Lung Diseases (RespiRare®), we created a national network and a web-linked database to collect data on pediatric ILD.