Expression of the cysteinyl leukotriene 1 receptor and glucocorticoid receptor-β in nasal polyps

TNF-α Regulates the Glucocorticoid Receptor Alpha Expression in Human Nasal Epithelial Cells Via p65-NF-κb and p38-MAPK Signaling Pathways

Background

Tumor necrosis factor (TNF)-α induces changes in the glucocorticoid receptor (GR) isoforms' expression in human nasal epithelial cells (HNECs) in chronic rhinosinusitis (CRS).

Objective

However, the underlying mechanism of TNF-α induced GR isoforms' expression in HNECs remains unclear. Here, we explored changes in inflammatory cytokines and glucocorticoid receptor alpha isoform (GRα) expression in HNECs.

Materials and Methods

To explore the expression of TNF-α in nasal polyps and nasal mucosa of CRS, fluorescence immunohistochemical analysis was employed. To investigate changes in inflammatory cytokines and GRα expression in HNECs, RT-PCR and western blotting were performed following the cells' incubation with TNF-α. Cells were pretreated with the nuclear factor-κB gene binding (NF-κB) inhibitor QNZ, the p38 inhibitor SB203580, and dexamethasone for one hour, then a TNF-α. Western blotting, RT-PCR, and immunofluorescence had been utilized for the cells' analysis and the ANOVA for the data analysis.

Results

The TNF-α fluorescence intensity was mainly distributed in nasal epithelial cells of nasal tissues. TNF-α prominently inhibited the expression of GRα mRNA from 6 to 24 h in HNECs. GRα protein was decreased from 12 to 24 h. Treatment with QNZ, SB203580, or dexamethasone inhibited the TNF-α and interleukin (IL)-6 mRNA expression and increased the GRα levels.

Conclusion

TNF-α induced changes in the GR isoforms' expression in HNECs, and it was mediated through p65-NF-κB and p38-MAPK signal transduction pathways, which could be considered a promising neutrophilic CRS treatment.

Increased lipopolysaccharide content is positively correlated with glucocorticoid receptor-beta expression in chronic rhinosinusitis with nasal polyps

Introduction

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a common and frequently occurring disease of the upper respiratory tract. The nasal instillation of the Gram‐negative (G⁻) bacterial product lipopolysaccharide (LPS) can induce not only acute sinusitis but also the development of CRSwNP in animal models. Nevertheless, the expression and distribution of LPS in patients with CRSwNP have not been investigated. And the study was to investigate the expression of LPS and its relationship with glucocorticoid receptors (GRs) in CRSwNP.

Methods

Multiple methods, including bacterial culture and immunohistochemistry, were used to detect and analyze nasal bacteria, plasma LPS content, and the levels of LPS and GR‐α/β, cluster of differentiation 68 (CD68), and myeloperoxidase (MPO) expression, as well as their relationship in CRSwNP.

Results

The number of G⁻ bacteria and Escherichia coli (E. coli) was not significantly different between CRSwNP subjects and the controls. However, the positive rate of LPS was much higher than that of E. coli in CRSwNP subjects and was significantly higher in noneosinophilic CRSwNP subjects than in eosinophilic CRSwNP subjects. Moreover, the LPS levels were positively correlated with GR‐β but not GR‐α expression in CRSwNP. Immunofluorescence assays showed that LPS was mainly detected in CD68⁺ macrophages and MPO⁺ neutrophils, in addition to histiocytes, in CRSwNP.

Conclusions

Persistent LPS in CRSwNP can lead to unresolved mucosal inflammation, eventually leading to tissue remodeling and the development of CRSwNP. Our findings suggest that increased LPS content and possible resistance to glucocorticoids may be one of the important pathogenic mechanisms of G⁻ bacteria in CRSwNP.

The role of cysteinyl leukotrienes and their receptors in refractory nasal polyps

Leukotriene signaling is essential in many diseases, including asthma, allergic rhinitis, atherosclerosis and inflammatory bowel disease. Nevertheless, the expression of cysteinyl leukotrienes (CysLTs) and its receptors (CYSLTRs) in different types of nasal polyps (NPs), and the role of their antagonist in the treatment of refractory chronic rhinosinusitis with nasal polyps (CRSwNP) are not well understood. The following study investigates the expression of CysLTs and CYSLTRs in different types of NPs, as well as the role of leukotriene receptor antagonist (montelukast) in refractory NPs. Our data showed that CysLTs and CYSLTRs were significantly elevated in CRSwNP group (p < 0.05), particularly in IL-5⁺NP patients^, compared to patients with chronic rhinosinusitis but without NPs (CRSsNP) and the control group. Furthermore, montelukast have shown the ability to inhibit the expression of MUC5AC, TSLP, IL-4, IL-5, IL-13, and TGF-β in NP explants after treatment with Staphylococcal Enterotoxins B (SEB). In addition, the patients treated by additional montelukast have better outcomes compared to those with INCS only. To conclude, our results demonstrate that the inhibition of CysLTs signaling by montelukast decreases the expression of cytokines and mucin in polyp explants, and in turn promotes the recovery in patients with refractory CRSwNP.

Expression of leukotriene and its receptors in eosinophilic chronic rhinosinusitis with nasal polyps

BACKGROUND

Cysteinyl leukotriene (LT) has been proposed in the pathogenesis of chronic rhinosinusitis with nasal polyps (CRSwNP). This study sought to examine the expression of the LT receptor (LTR) in CRSwNP patients and evaluate the potential role of LTR antagonist (LTRA) in the management of eosinophilic CRSwNP (ECRS) patients.

METHODS

Nasal polyps and uncinate process tissues were collected from 18 ECRS patients, 13 non-eosinophilic CRSwNP (non-ECRS) patients, and 16 control subjects. The messenger RNA (mRNA) and protein expression of LTR (cysteinyl leukotriene receptor 1 [CysLT1R] and cysteinyl leukotriene receptor 2 [CysLT2R]) was examined using quantitative reverse-transcription polymerase chain reaction (qRT-PCR), immunohistochemistry, and Western blot analysis. Moreover, the effects of LTRA and steroids on total nasal symptom scores (TNSS) of uncontrolled ECRS patients were evaluated.

RESULTS

The mRNA and protein expression of CysLT1R and CysLT2R was significantly increased in polyp tissues compared with healthy controls (p < 0.05). Compared with the non-ECRS subset, the ECRS subset showed significantly increased expression of CysLT1R and CysLT2R, as well as leukotriene C4 (LTC4) and leukotriene D4 (LTC4) levels (p < 0.05). Moreover, combined LTRA and steroids significantly decreased TNSS more than steroids alone in uncontrolled ECRS patients (p < 0.01).

CONCLUSION

Our findings indicate that LTR was differentially expressed between ECRS and non-ECRS patients, and that LTRA may be used as an additional therapy for ECRS patients.