The role of Th17 lymphocytes in the pathogenesis of chronic rhinosinusitis

Chronic rhinosinusitis (CRS) encompasses inflammatory conditions affecting the nasal and paranasal sinus mucosa. Two major subtypes are distinguished by the presence (CRSwNP) or absence (CRSsNP) of nasal polyps. This review examines the role of T helper 17 (Th17) cells and interleukin-17 (IL-17) cytokines in CRS immunopathology. Th17 lymphocytes produce inflammatory mediators, including IL-17A and IL-17F, which can disrupt sinonasal epithelial barrier function. Multiple studies correlate IL-17 levels and Th17 signaling with mucosal inflammation in CRS patients. However, significant endotypic and phenotypic variability modifies IL-17 involvement. CRSwNP often presents hallmark Th2-linked eosinophilic inflammation, while CRSsNP and subsets of Asian CRSwNP display Th17-associated neutrophilia. Overall, the literature implicates Th17 and IL-17 activity in CRS, but the heterogeneity of immunological subtypes mediates variable cytokine profiles. Further research into precise immunopathogenic mechanisms is needed to elucidate the contribution of Th17/IL-17 to disease and personalized therapeutic development.