[Research progress on epithelial mucosal barrier impairment contributing to chronic rhinosinusitis]

Chronic rhinosinusitis （CRS） is defined as sinonasal mucosal inflammation persisting for >12 weeks and presents with nasal congestion, rhinorrhea, facial pain/pressure and olfactory impairment. CRS markedly impairs quality of life and imposes a heavy economic burden on health-care systems. Recent research has shifted the pathophysiological paradigm from simple mechanical obstruction to an epithelial-barrier-centred model that emphasizes immune dysregulation and cellular aberrations. Its complex aetiology includes ciliary dysfunction; dysbiosis; cytokine imbalance; epithelial-mesenchymal transition （EMT）; disruption of tight junctions by inflammatory mediators; environmental pollutants; allergens; cigarette smoke; and neuroendocrine disturbance-factors that are especially prominent in eosinophilic CRS with nasal polyps. Here we systematically review structural alterations and key molecular mechanisms driving epithelial barrier breakdown in CRS, providing a theoretical basis for future barrier-targeted therapies.