Background Chronic rhinosinusitis without nasal polyps (CRSsNP) and with nasal polyps (CRSwNP) is characterized by persistent inflammation of sinonasal mucosa. Glucocorticoid-induced leucine zipper (GILZ) is a recently described anti-inflammatory mediator.
Objective Here we analysed the expression of GILZ in CRSsNP and CRSwNP, its association with response to surgery, and its cytokine-driven expression regulation in the upper airways.
Methods The messenger RNA (mRNA) and protein expression of GILZ in 33 CRSsNP, 32 CRSwNP, and 11 control samples was assessed by means of a quantitative RT-PCR and immunohistochemistry, respectively. Nasal explant culture was used to investigate the effect of IFN-γ, IL-4, IL-13, IL-1β, and TNF-α on GILZ mRNA expression in normal sinonasal mucosa.
Results The GILZ mRNA and protein expression was significantly suppressed in both CRSsNP and CRSwNP patients compared with controls. No significant difference in GILZ expression was found between CRSsNP and CRSwNP patients. Comparing patients responsive and patients recalcitrant to surgery, a significant further decrease of GILZ expression was found in recalcitrant patients both in the CRSsNP and in the CRSwNP group. IL-1β, TNF-α, IL-4, and IL-13 reduced, whereas IFN-γ enhanced GILZ mRNA levels in the sinonasal mucosa.
Conclusion Down-regulated expression of GILZ may contribute to the pathogenesis of CRSsNP and CRSwNP and associate with response to surgery. GILZ expression in the upper airways can be regulated differentially by different cytokines.
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