Asthma is the most frequent chronic inflammatory disease in children. The main cause of asthma exacerbations is the viral infection of the bronchial epithelium (BE). Rhinoviruses (RV) are detected in 85 % of asthma exacerbations in children knowing that the prevalence of RVC represents 67.5 % in children and associated with severe exacerbations. In adults, it has been shown that BE energetic metabolism shifts from mitochondrial oxidative phosphorylation towards glycolysis compared to healthy BE [1Abilash Ravi, Annika W.M., Goorsenberg, Annemiek Dijkhuis, Barbara S., Dierdorp, et al. Metabolic differences between bronchial epithelium from healthy individuals and patients with asthma and the effect of bronchial thermoplasty JACI 2021 ;  148 : 1236-1248

Cliquez ici pour aller à la section Références]. In healthy BE, viral infection of BE promotes a metabolic rewiring in favor for glucose utilization through glycolysis rather than mitochondrial metabolism, impacting the muco-ciliary clearance [2Michi A.N., Yipp B.G., Dufour A., Lopes F., Proud D. PGC-1α mediates a metabolic host defense response in human airway epithelium during rhinovirus infections Nat Commun 2021 ;  12 : 3669

Cliquez ici pour aller à la section Références]. We suppose that RV infection enhances BE glycolytic metabolism affecting the BE function in childhood asthma. We will analyse both the energetic metabolism and the functions of BE under RV infections on childhood non-asthma and asthma BE.

Cell culture.

BE cells were obtained from children bronchi fibroscopic brushing. 100 000 cells were seeded on ALI transwell (0.4μm pores, Corning Incorporated Transwell, Costar) with ALI medium (StemCell) at basal pole.

RV infection.

We infected BE with RVC MOI 0.1. The mix was removed 1h after and the experiences were realized 24h after infection.

Cellular oxygen consumption rate (OCR).

OCR was measured on intact cells at 37°C in a 2mL thermostatically monitored chamber (2.5×105 cells/mL/run) using an Oroboros O₂k instrument (Oroboros Instruments).

Ciliary beating frequency.

Ciliary beating frequency of BE were measured using videomicroscopy Leica DMi8 (Leica Microsystems) coupled to a high-speed camera sCMOS Flash 4.0 camera (Hamamatsu) available at The Bordeaux Imaging Center. Using MATHLAB program, the images were analyzed after application of the Fourier transform to determine the most represented beat frequency.

Under basal condition, asthmatic children BE were metabolically different from non-asthmatic children BE. Proteomic analysis, OCR and glycolytic enzymes expression indicated that asthmatic BE were using more glucose through glycolysis rather that mitochondrial metabolism. RV infection aggravate the shift within non-asthmatic BE. In association, we observed a defective ciliary beating frequency and efficiency in asthmatic children BE compared to non-asthmatic children BE.

Our study revealed that non-asthmatic and asthmatic children BE appeared metabolically different, in basal conditions but also after RV infection. BE barrier functions seemed less efficient in asthmatic children BE compared to non-asthmatic BE. To go further, we will deepen how RV infection can modulate energetics and how it will affect BE functions.