Innate immune system in nasal and upper respiratory epithelial cells

The innate immune system in nasal and upper respiratory epithelial cells represents the primary defense mechanism against inhaled pathogens, allergens, and environmental pollutants. This complex system integrates physical barriers, such as the mucociliary escalator, with molecular sensing via pattern recognition receptors (PRRs) like Toll-like receptors (TLRs) and NOD-like receptors (NLRs) (StatPearls, 2023; https://www.ncbi.nlm.nih.gov/books/NBK541071/). Upon detection of pathogen-associated molecular patterns, epithelial cells initiate signaling cascades that result in the secretion of antimicrobial peptides, interferons, and pro-inflammatory cytokines (Nature Reviews Immunology, 2015; https://doi.org/10.1038/nri3821). These responses are essential for limiting viral replication and bacterial colonization at the portal of entry. However, dysregulation of these innate pathways is a hallmark of chronic inflammatory conditions, including allergic rhinitis and chronic rhinosinusitis (Journal of Allergy and Clinical Immunology, 2018; https://doi.org/10.1016/j.jaci.2018.06.006). Pharmacological modulation of this system typically involves the use of corticosteroids to suppress broad inflammatory outputs or the development of specific PRR agonists to boost local antiviral immunity (Frontiers in Immunology, 2020; https://doi.org/10.3389/fimmu.2020.01046). Because it comprises a vast network of interacting proteins and cell types, it is characterized as a biological system rather than a single molecular target.

Other names

Nasal mucosal immunityUpper respiratory tract innate immunityAirway epithelial defense systemNasal epithelial innate immune response

Drugs interacting with this system typically function by activating pattern recognition receptors to induce antiviral states, utilizing corticosteroids to inhibit the transcription of pro-inflammatory cytokines, or employing sympathomimetics and anticholinergics to modulate mucosal secretions and vascular tone.