Low-Dose Radiation Sensitizes Human Nasal Epithelium to Viral Inflammation Despite Preserved Structural Integrity

INTRODUCTION: Patients receiving radiotherapy for nasopharyngeal carcinoma often experience prolonged nasal epithelial dysfunction and recurrent infections. However, the dose-dependent effects of radiation on epithelial integrity and antiviral immune function remain incompletely defined. METHODS: Human nasal epithelial cells (hNECs) were differentiated at an air-liquid interface (ALI) and exposed to gamma irradiation (0, 1, 2, 4, 8, or 16 Gy) on ALI day 0 to define dose-dependent epithelial injury. DNA damage, epithelial cell number, and proliferative capacity were assessed after irradiation. To model post-irradiation viral challenge, cultures exposed to 1 Gy were infected with rhinovirus on ALI day 28, followed by assessment of ciliary beat frequency (CBF), transepithelial electrical resistance (TEER), immunofluorescence, cytospin analysis, and gene expression by qRT-PCR. RESULTS: Increasing radiation doses progressively exacerbated epithelial injury. Higher doses (8-16 Gy) caused marked epithelial loss and were not pursued for detailed phenotypic analyses. At 4 Gy, hNECs exhibited impaired ciliogenesis, impaired barrier integrity, and reduced proliferative capacity, whereas 2 Gy primarily caused structural abnormalities characterized by reduced acetylated α-tubulin and MUC5AC signals and an increased cell aspect ratio. In contrast, 1 Gy induced transient DNA damage while largely preserving epithelial structure by day 28. Upon rhinovirus infection, 1 Gy-exposed hNECs exhibited enhanced antiviral and inflammatory responses, including increased type III interferons, interferon-stimulated genes, inflammatory mediators, and intercellular adhesion molecule-1 (ICAM-1) expression. CONCLUSION: These findings suggest that low-dose radiation may alter epithelial immune responsiveness even in the absence of overt structural damage, leading to amplified antiviral and inflammatory gene induction following rhinovirus challenge. Our results provide novel insights into how prior radiation exposure may reshape mucosal responses to viral infection and thereby contribute to persistent sinonasal inflammation after radiotherapy.