[Hypoxic stimulation leads to the changes of inflammatory factors in mucosal epithelial cells of nasal polyps]

Objective: To investigate the roles of hypoxic stimulation in the pathogenesis of chronic rhinosinusitis with nasal polyps (CRSwNP) by comparing the variation and differences of inflammatory factors secreted from epithelial cells of nasal polyps and normal nasal mucosa under hypoxic stimulation. Methods: Sixty-eight patients who were diagnosed with CRSwNP from June 2015 to January 2018 at China-Japan Union Hospital of Jilin University were analyzed, including 36 males and 32 females, aged (45.2±12.5) years. Nasal polyps mucosa was included in CRS-NP group and inferior turbinate mucosa was included in CRS-IT group. According to the degree of eosinophil infiltration in histopathologic results, each of these two groups was further divided into eosinophil infiltration and non-eosinophil infiltration as Eos-NP group (n=34), Non-Eos-NP group (n=34), Eos-IT group (n=20) and Non-Eos-IT group (n=20). The inferior turbinate mucosa of twenty-five patients who were diagnosed with cyst of paranasal sinus or deviation of nasal septum was classified as control group (n=25), including 14 males and 11 females, aged (42.8±10.2) years. The expression of interleukin 17A (IL-17A), interferon γ (IFN-γ), tumor necrosis factor α (TNF-α) and hypoxia-inducible factor 1α (HIF-1α) in each group was analyzed by immunohistochemical staining. After 0, 24 and 48 h hypoxic stimulation, the secretion of IL-17A, IFN-γ, TNF-α in primary nasal mucosa epithelial cells of each group was tested by enzyme-linked immune sorbent assay (ELISA) experiment; the expression of HIF-1α was tested by immunofluorescent staining and imaging and Western blot. SPSS 17.0 software and two-way ANOVA were used for statistical analysis. Results: Immunohistochemical staining showed that the expression of IL-17A and TNF-α was much higher in control group (optical density (OD) value was 0.37±0.03, 0.53±0.02, respectively) and the expression of IFN-γ and HIF-1α was much higher in Eos-IT group (OD value was 0.47±0.03, 0.39±0.02, respectively). The secretion of IL-17A and TNF-α was much lower in control group than that in other groups under normal condition. After 48 h hypoxic stimulation, the secretion of IL-17A and TNF-α was much higher in control group compared with other groups. The secretion of IFN-γ in Eos-NP group was much higher than that in control group under normal condition ((13.7±1.3) pg/ml vs (11.1±1.6) pg/ml, P<0.05). After 48 h hypoxic stimulation, there was no difference of IFN-γ between control group and Eos-NP group. The expression of HIF-1α decreased in Eos-NP group and Non-Eos-NP group while increased in CRS-IT group and control group upon prolonged exposure to hypoxia. HIF-1α was mostly located at cytoplasm of epithelial cells in control and CRS-IT group while mainly located at nucleus of epithelial cells in CRS-NP group. Conclusions: The secretion of IL-17A, TNF-α, IFN-γ and the expression of HIF-1α show significant difference between normal nasal mucosa, polyps and inferior turbinate of CRSwNP under hypoxic stimulation, presenting different subcellular localization. This illustrates the proteins above are involved in transcription and regulation of the gene responsible for the pathogenesis of CRSwNP.