Metabolomics of Allergic Airway Diseases Across the Lifespan: From Rhinitis to Asthma

Allergic airway diseases, including allergic rhinitis and asthma, are complex conditions characterized by chronic inflammation, immune dysregulation, and heterogeneous clinical manifestations. Although they share immunopathological mechanisms, their biochemical profiles may differ. Metabolomics provides a powerful approach to investigating pathways linking environmental exposures, immune responses, and disease phenotypes. This review synthesizes current metabolomic evidence on allergic rhinitis and asthma in pediatric and adult populations, focusing on shared and disease-specific alterations and their clinical implications. Available studies consistently identify disruptions in amino acid metabolism, including arginine–proline, tryptophan–kynurenine, histidine, and branched-chain amino acids, as well as alterations in sphingolipid, glycerophospholipid, and arachidonic acid pathways and oxidative stress. In allergic rhinitis, metabolic changes appear predominantly related to mucosal processes and microbiota-derived metabolites, including short-chain fatty acids, adenosine, and tryptophan catabolites, supporting a potential gut–nose interaction. Conversely, asthma shows broader systemic alterations involving energy and lipid metabolism, including increased sphingosine-1-phosphate, altered carnitine levels, and markers of mitochondrial dysfunction, reflecting enhanced inflammatory and oxidative activity. Emerging evidence further suggests that immune-cell metabolic reprogramming may contribute to disease severity and treatment response. Overall, metabolomics provides an integrated framework for understanding the biochemical heterogeneity of allergic airway diseases and may facilitate biomarker discovery and precision-medicine approaches to diagnosis, phenotyping, and targeted therapy. Compared with previous narrative reviews, this work integrates pediatric and adult evidence in disease-specific summary tables and outlines a translational research agenda focused on clinical validation and future implementation.