Purpose: Various immune cells, including eosinophils and neutrophils, are known to contribute to the development of chronic rhinosinusitis with nasal polyps (CRSwNP). However, the current understanding of the role of neutrophils in the development of CRSwNP still remains unclear. Therefore, we investigated risk factors for refractoriness of CRSwNP in an Asian population. Methods: Protein levels of 17 neutrophil-related mediators in nasal polyps (NPs) were determined by multiplex immunoassay, and exploratory factor analysis using principal component analysis was performed. Immunofluorescence analysis was conducted to detect human neutrophil elastase (HNE) or myeloperoxidase (MPO)-positive cells. Tissue eosinophilic nasal polyp (ENP) and tissue neutrophilia (Neu high) were defined as greater than 70 eosinophils and 20 HNE-positive cells, otherwise was classified into non-eosinophilic nasal polyp (NENP) and absence of tissue neutrophilia (Neu low). Results: In terms of disease control status, NENP-Neu low patients showed the higher rate of disease control than NENP-Neu high and ENP-Neu high patients. Linear by linear association demonstrated the trend in refractoriness from NENP-Neu low to NENP-Neu high or ENP-Neu low to ENP-Neu high. When multiple logistic regression was performed, tissue neutrophilia (hazard ratio, 4.38; 95% confidence interval, 1.76-10.85) was found as the strongest risk factor for CRSwNP refractoriness. Additionally, exploratory factor analysis revealed that interleukin (IL)-18, interferon-γ, IL-1Ra, tumor necrosis factor-α, oncostatin M, and MPO were associated with good disease control status, whereas IL-36α and IL-1α were associated with refractory disease control status. In subgroup analysis, HNE-positive cells and IL-36α were significantly upregulated in the refractory group (P = 0.0132 and P = 0.0395, respectively), whereas MPO and IL-18 showed higher expression in the controlled group (P = 0.0002 and P = 0.0009, respectively). Moreover, immunofluorescence analysis revealed that IL-36R + HNE +-double positive cells were significantly increased in the refractory group compared to the control group. We also found that the ratio of HNE-positive cells to α1 anti-trypsin was increased in the refractory group.

Purpose Recent studies have revealed the pathogenic role of interleukin (IL)-22 in atopic dermatitis and asthma. However, little is known about the role of IL-22 in the pathophysiology of chronic rhinosinusitis with nasal polyps. We aimed to investigate the expression of IL-22 and its pathogenic function in type 2 immune reactions of nasal polyps (NP). Methods Protein levels of inflammatory mediators were determined by multiplex immunoassay, and principal component analysis (PCA) was performed. Immunofluorescence analysis and mast cell culture were used to determine the cellular sources of IL-22. Normal human bronchial epithelial (NHBE) cells were stimulated using IL-22 in combination with diverse cytokines, and thymic stromal lymphopoietin (TSLP) was measured. Results IL-22 expression was not up-regulated in NP compared with control tissues, but IL-22-high NP revealed distinct features characterized by type 2 inflammatory cytokines such as chemokine (C-C motif) ligand (CCL)-11, CCL-24, and IL-5 on the PCA. Additionally, IL-22 positively correlated with type 2 immune mediators and the disease severity in NP. For the localization of the cellular sources of IL-22 in eosinophilic NP, it was expressed in cells mostly composed of eosinophil peroxidase-positive cells and partially of tryptase-positive cells. The human mast cell line, LAD2 cells, released IL-22 mediated by immunoglobulin E. Moreover, IL-22 receptor subunit alpha-1 (IL-22Ra1) expression was significantly increased in NP. IL-22Ra1 was up-regulated with poly(I:C) stimulation in NHBE cells. Furthermore, TSLP production was enhanced when stimulated with a combination of IL-13, poly(I:C), and IL-22. Treatment with anti-IL-22Ra1 also inhibited IL-22-induced enhancement of TSLP production. Conclusion IL-22 was associated with type 2 inflammatory reactions in NP. The IL-22/IL-22Ra1 axis was enhanced and might be involved in type 2 inflammatory reactions via TSLP production in NP.