Alao, Jude OluwapelumiBamigboye, Favour Oluwadara2025-10-302025-10-302025-10-20Medicine in Microecology, ISSN: 2590-0978 (Print); 2590-0978 (Online), Elsevier, 100153-100153. doi: 10.1016/j.medmic.2025.1001532590-09782590-0978http://hdl.handle.net/10292/20030The nasal and gut microbiomes are recognised as key regulators of mucosal and systemic immunity. While each has been studied extensively in isolation, evidence suggests they are connected through a bidirectional network of immune signalling, microbial metabolites, and barrier integrity, forming what may be termed “the nasal–gut microbiome axis”. This review synthesises current knowledge on the composition and function of these microbiomes, highlighting shared features, environmental influences, and patterns of dysbiosis observed in conditions such as asthma, allergic rhinitis, and chronic rhinosinusitis. We examine potential mechanisms of cross-talk, including cytokine and chemokine exchange, short-chain fatty acid mediated epigenetic regulation, and dendritic cell–driven immune priming across mucosal sites. Clinical implications are explored, with particular attention to dual-site microbiome modulation strategies, concurrent nasal–gut microbial profiling for diagnostics, and microbiome-informed precision therapies. Despite promising early evidence, knowledge gaps persist, particularly the scarcity of longitudinal, multi-omic studies and mechanistic human data. Framing the nasal and gut microbiomes as components of an integrated mucosal network, this review aims to advance understanding of their connection, and encourage research that could transform prevention and treatment strategies for immune-mediated respiratory disease.© 2025 The Authors. Published by Elsevier B.V. Creative Commons. This is an open access article distributed under the terms of the Creative Commons CC-BY license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. You are not required to obtain permission to reuse this article.MicrobiotaGastrointestinal microbiomeNasal cavity/microbiologyImmune systemDysbiosisShort-chain fatty acidsRespiratory tract diseases/microbiologyJournal ArticleOpenAccess10.1016/j.medmic.2025.100153