Type 1/type 2 inflammatory cytokines correlate with olfactory function in patients with chronic rhinosinusitis

Background: Olfactory dysfunction secondary to chronic rhinosinusitis (CRS) has been highly associated with impaired quality of life. Asian CRS patients showed a distinct inflammatory profile, with less type 2 endotype compared with European and North American. This study aimed to explore the pattern of the inflammatory cytokines in CRS patients from China and their association with olfactory function. Methods: Institutional review board-approved prospective study in which the olfactory function of 71 CRS patients was assessed with Sniffin' Sticks before the nasal endoscopic surgery. A set of cytokines and inflammatory mediators including type 1 and type 2 inflammatory cytokines were measured in nasal mucus by using a multiplex flow cytometric bead assay (CBA). Baseline characteristics in CRS patients were collected and the Spearman r statistic was performed to assess the association of olfactory function with cytokines and inflammatory mediators. Results: A total of 71 nasal mucus samples of CRS patients, including 25 chronic rhinosinusitis without nasal polyposis (CRSsNP) patients and 46 chronic rhinosinusitis with nasal polyposis (CRSwNP) patients, were evaluated in this study. The nasal mucus levels of type 1 inflammatory cytokine IFN-gamma (interferon-gamma), type 2 inflammatory cytokines including IL-4, IL-5 and GM-CSF (granulocyte-macrophage colony-stimulating factor) and anti-inflammatory cytokine IL-10 were significantly and inversely correlated with olfactory function in total patients with CRS (r = - 0.308, p = 0.009; r = -0.250, p = 0.036; r = - 0.399, p = 0.001; r = - 0.269, p = 0.023; r = - 0.273, p = 0.021, respectively). In CRSsNP, the olfactory function was inversely correlated with levels of type 1 inflammatory cytokine TNF-alpha (tumor necrosis factor-alpha) (r = - 0.637, p = 0.001) and IL-10 (r = - 0.468, p = 0.018). Nevertheless, the olfactory function in CRSwNP was inversely correlated with type 2 inflammatory cytokines including IL-4 (r = - 0.303, p = 0.041) and IL-5 (r = -0.383, p = 0.009). Conclusion: Both type 1 and type 2 inflammatory cytokines may contribute to the pathogenesis of CRS-associated olfactory dysfunction in the Chinese population.