Fig. 1: Early-life exposure to low dose of HDM establishes airway tolerance to the allergen.

a Schematic for low-dose HDM-induced early-life airway tolerance model. Other groups for comparison included pre-exposure to either PBS (No HDM) or a higher dose of HDM. b, c Analysis of lung tissue isolated from WT mice sensitized to a low dose of HDM (0.5 µg, referred to here as Low HDM) or a high dose of HDM (5.0 µg, referred to here as High HDM) or without any HDM pre-exposure (referred to as No HDM) at 2 weeks of age, followed by challenges with 25 µg of HDM at 6 weeks of age. Animals without any exposure to vehicle or HDM were considered as naïve controls. Histological assessment of lung sections after PAS staining showing cellular infiltration around blood vessels and airways (black arrow) and mucus staining in the small airways (red arrow). Scale bar:100 µm. Data shown in (b) are representative results and in (c) are median ± IQR summarized from two independent experiments with 6 mice per group. d Analysis of differential cell counts showing frequency and absolute number of inflammatory cells in the BAL fluid. Data shown are median ± IQR combined from three independent experiments with 7–13 mice per group in pooled data. e Expression of Ifng, Il-13 and Il-17a mRNA in lung tissue was assessed by RT-qPCR methods. Data shown are median ± IQR of pooled data from two independent experiments with 4–6 mice per group. f Representative flow plots of the percentage of Th2 cells (GATA-3⁺IL-13⁺ and GATA-3⁺IL-5⁺) (gated on live CD4⁺TCRβ⁺FoxP3⁻cells) and FoxP3⁻IL-10⁺ and FoxP3⁺IL-10⁺ populations (gated on live CD4⁺TCRβ⁺) in the lungs. g quantification of the percentages of cell types shown in (e) in each mouse. Data shown are median ± IQR combined from three independent experiments with 6–10 mice per group (pooled). Kruskal–Wallis with Dunn’s post hoc test (c, d, e, g). *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001; ^nsP > 0.05.