ERS International Congress 2020: highlights from the Paediatric Assembly.

In this review, the Paediatric Assembly of the European Respiratory Society (ERS) presents a summary of the highlights and most relevant findings in the field of paediatric respiratory medicine presented at the virtual ERS International Congress 2020. Early Career Members of the ERS and Chairs of the different Groups comprising the Paediatric Assembly discuss a selection of the presented research. These cover a wide range of research areas, including respiratory physiology and sleep, asthma and allergy, cystic fibrosis, respiratory infection and immunology, neonatology and intensive care, epidemiology, bronchology and lung and airway development. Specifically, we describe the long-term effect in lung function of premature birth, mode of delivery and chronic respiratory conditions such as cystic fibrosis. In paediatric asthma, we present risk factors, phenotypes and their progression with age, and the challenges in diagnosis. We confirm the value of the lung clearance index to detect early lung changes in cystic fibrosis. For bronchiectasis treatment, we highlight the importance of identifying treatable traits. The use of biomarkers and genotypes to identify infants at risk of long-term respiratory morbidity is also discussed. We present the long-term impact on respiratory health of early life and fetal exposures to maternal obesity and intrauterine hypoxia, mechanical ventilation hyperoxia, aeroallergens, air pollution, vitamin A deficient intake and bronchitis. Moreover, we report on the use of metabolomics and genetic analysis to understand the effect of these exposures on lung growth and alveolar development. Finally, we stress the need to establish multidisciplinary teams to treat complex airway pathologies.

Airway dendritic cell maturation in children exposed to air pollution.

Urban particulate matter (PM) enhances airway dendritic cell (DC) maturation in vitro. However, to date, there are no data on the association between exposure to urban PM and DC maturation in vivo. We sought to determine whether exposure of school-age children (8 to 14 y) to PM was associated with expression of CD86, a marker of maturation of airway conventional DCs (cDC). Healthy London school children underwent spirometry and sputum induction. Flow cytometry was used to identify CD86 and CCR7 expression on cDC subsets (CD1c+ cDC2 and CD141+ cDC1). Tertiles of mean annual exposure to PM ≤ 10 microns (PM10) at the school address were determined using the London Air Quality Toolkit model. Tertiles of exposure from the 409 children from 19 schools recruited were; lower (23.1 to 25.6 µg/m3, n = 138), middle (25.6 to 26.8 µg/m3, n = 126), and upper (26.8 to 31.0 µg/m3, n = 145). DC expression was assessed in 164/370 (44%) children who completed sputum induction. The proportion (%) of cDC expressing CD86 in the lower exposure tertile (n = 47) was lower compared with the upper exposure tertile (n = 49); (52% (44 to 70%) vs 66% (51 to 82%), p<0.05). There was a higher percentage of cDC1 cells in the lower tertile of exposure (6.63% (2.48 to 11.64) vs. 2.63% (0.72 to 7.18), p<0.05). Additionally; children in the lower exposure tertile had increased FEV1 compared with children in the upper tertile; (median z-score 0.15 (-0.59 to 0.75) vs. -0.21 (-0.86 to 0.48), p<0.05. Our data reveal that children attending schools in the highest areas of PM exposure in London exhibit increased numbers of "mature" airway cDCs, as evidenced by their expression of the surface marker CD86. This data is supportive of previous in vitro data demonstrating an alteration in the maturation of airway cDCs in response to exposure to pollutants.

Use of cleaner-burning biomass stoves and airway macrophage black carbon in Malawian women.

Exposure to particulate matter (PM) from burning of biomass for cooking is associated with adverse health effects. It is unknown whether or not cleaner burning biomass-fuelled cookstoves reduce the amount of PM inhaled by women compared with traditional open fires. We sought to assess whether airway macrophage black carbon (AMBC) - a marker of inhaled dose of carbonaceous PM from biomass and fossil fuel combustion - is lower in Malawian women using a cleaner burning biomass-fuelled cookstove compared with those using open fires for cooking. AMBC was assessed in induced sputum samples using image analysis and personal exposure to carbon monoxide (CO) and PM were measured using Aprovecho Indoor Air Pollution meters. A fossil-fuel exposed group of UK women was also studied. Induced sputum samples were obtained from 57 women from which AMBC was determined in 31. Median AMBC was 6.87µm2 (IQR 4.47-18.5) and 4.37µm2 (IQR 2.57-7.38) in the open fire (n=11) and cleaner burning cookstove groups (n=20), respectively (p=0.028). There was no difference in personal exposure to CO and PM between the two groups. UK women (n=5) had lower AMBC (median 0.89µm2, IQR 0.56-1.13) compared with both Malawi women using traditional cookstoves (p<0.001) and those using cleaner cookstoves (p=0.022). We conclude that use of a cleaner burning biomass-fuelled cookstove reduces inhaled PM dose in a way that is not necessarily reflected by personal exposure monitoring.