[Expression and cellular provenance of interleukin 17A in non-eosinophilic chronic rhinosinusitis with nasal polyps]

Objective: To investigate the expression and cellular provenance of interleukin 17A (IL-17A) in non-eosinophilic chronic rhinosinusitis with nasal polyps (nECRSwNP), and to analyze the possible reasons for its different expression. Methods: Samples were collected from 14 patients with eosinophilic chronic rhinosinusitis with nasal polyps (ECRSwNP) and 28 patients with nECRSwNP, who underwent functional endoscopic sinus surgery in the Third Affiliated Hospital of Sun Yat-sen University from January 2017 to May 2018, including 33 males and 9 females, with the age ranging from 18 to 65 years old. Enzyme linked immune sorbent assay (ELISA) and flow cytometry were used to investigate the expression and cellular origins of IL-17A in the nasal tissue of ECRSwNP and nECRSwNP groups. Then the difference of quantity and differentiation ability of the major cells producing IL-17A between ECRSwNP and nECRSwNP groups were analyzed by flow cytometry. Finally, the expressions of IL-6, transforming growth factor-β(TGF-β), and IL-23, which were considered as the important factors in promoting Th17/Tc17 differentiation in CRSwNP and their correlation with IL-17A, were analyzed by ELISA. Statistical analysis was performed using IBM SPSS 20. Results: The IL-17A protein levels and IL-17A(+)lymphocyte percentages were higher in nECRSwNP group compared with that of the ECRSwNP group (158.56 (167.76) pg/ml (M(QR)) vs. 9.42 (11.33) pg/ml, 10.21%±1.54% (x±s) vs. 3.93%±0.80%, Z=2.95, t=3.62, all P<0.01). Tc17 cells (CD8(+)T cells producing IL-17A) and Th17 cells (CD4(+)T cells producing IL-17A) were major IL-17A producers in both ECRSwNP and nECRSwNP group. Further analysis revealed that there was no significant difference in quantity of CD8(+)and CD4(+)T cells between ECRSwNP and nECRSwNP group, but the differentiation ability about CD8(+)and CD4(+)T cells differentiating into Tc17 and Th17 in nECRSwNP group was stronger than that in ECRSwNP. The high expressions of IL-6 and TGF-β, which were considered as the important factors in promoting Th17/Tc17 differentiation were also found in nECRSwNP group compared with ECRSwNP (56.07 (234.25) pg/ml vs. 8.27 (12.51) pg/ml, (5.44±0.34) pg/ml vs. (4.17±0.22) pg/ml, Z=2.426, t=2.29, all P<0.05). But the difference in expression of IL-23 was not significant difference between the two groups. Moreover, the expression of IL-17A showed significantly positive correlation with IL-6 (r=0.615, P=0.009). No positive correlation between IL-17A and TGF-β or IL-23 was observed. Conclusions: The expression of IL-17A in nasal mucosa of nECRSwNP patients is significantly higher than that of ECRSwNP, which is due to the increase of expression and differentiation of Tc17/Th17 cells. IL-17A shows positive correlation with IL-6 in CRSwNP, which is the important factor in promoting Th17/Tc17 differentiation.