Microplastics in pediatric asthma: Clinical associations with disease severity

Abstract

Background Respiratory exposure to microplastics (MPs) is increasingly recognized as a potential contributor to chronic airway disease, but the MPs burden in children with asthma and its relationship to disease remain poorly defined. Methods In this cross-sectional study, sputum samples from 46 children with asthma were analyzed by pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) to quantify six prevalent synthetic polymers. Associations between MPs burden, asthma control status, pulmonary function, and airway inflammation were examined. To explore epithelial responses, patient-derived human alveolar organoids were exposed to polyethylene (PE) particles and subjected to bulk RNA sequencing. Results MPs were identified in all 46 sputum samples from children with asthma, with a median total concentration of 21.12 μg/mL. Polystyrene (PS) was the most frequently detected polymer, present in 100% of the samples, while PE exhibited the highest median mass concentration at 13.96 µg/mL. Children with poorly controlled asthma demonstrated significantly elevated total MP burdens compared to those with well-controlled asthma. The total MP concentration showed a negative correlation with FEV₁% predicted, FVC% predicted, and the Asthma Control Test score. Transcriptomic analysis of PE-exposed alveolar organoids revealed 1297 differentially expressed genes, with enrichment in pathways associated with ferroptosis, apoptosis, p53 signaling, and inflammatory cytokine networks. Conclusions Respiratory MPs burden is universal in this pediatric asthma cohort and associates with poor disease control. Exploratory transcriptomic analysis nominates ferroptosis-associated and pro-inflammatory pathways as candidate mechanisms warranting functional validation in future work.