Bridging environmental pollution and immune dysregulation: How microplastics disrupt gut homeostasis to promote allergic diseases.

Parallel increases in microplastic (MP) pollution and allergic diseases suggest an environmental link in allergy pathogenesis. While intestinal barrier dysfunction and dysbiosis are hallmark features of allergic diseases, the mechanisms by which persistent MPs drive these processes remain unclear. This review proposes a mechanistic pathway where orally ingested MPs disrupt the intestinal barrier through physical and chemical toxicity, precipitating functional dysbiosis. Specifically, MPs suppress key short-chain fatty acid (SCFA)-producing commensals. The resulting SCFA deficit impairs the "gut-airway axis," weakening respiratory immune tolerance and increasing allergen susceptibility. We further argue for integrating gut health assessments into standardized allergy diagnostics and treatments. Despite this novel perspective, significant knowledge gaps remain regarding causality, dose-response relationships, and specific biomarkers. Addressing these challenges is critical for translating scientific findings into public health policies and clinical interventions to mitigate the rising global burden of allergic diseases.