Downregulation of caveolin-1 in chronic rhinosinusitis with and without nasal polyps

Multiple gene expression profiling suggests epithelial dysfunction in polypoid chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a heterogeneous inflammatory disorder resulting from a complex gene-environment interaction. Although its aetiology remains elusive, numerous studies reported gene expression alterations of factors apparently implicated in all aspects of the inflammatory response. However, most investigations are limited, unconfirmed analyses of a single gene. Moreover, studies concerning multiple gene expression analyses, usually on inflammatory mediators (e.g. cytokines), show contrasting outcomes in part due to use of heterogeneous samples or methodologies with limited power. In this scenario, our goal was to simultaneously evaluate the expression of a panel of selected genes (AQP5, MUC5AC, CAV1, LTF, COX2, PGDS, TNFα, TGFβ1, MGB1) potentially involved in CRS inflammatory mechanisms. While most of the samples collected were excluded from the analysis because of poor quality RNA, we were able to demonstrate statistically significant downregulation of the AQP5, CAV1, LTF, MGB1 genes in a specific subset of polypoid CRS (patients without typical comorbidities), which might suggest relevant underlying epithelial dysfunction. Further studies are needed to enrich our knowledge on the pathogenesis of CRS. Forthcoming approaches might utilise next-generation RNA sequencing and comprehensive bioinformatics analyses to better characterise the transcriptome profiles of CRS endotypes.

Distinctive expression profiles of Caveolin-1 and Notch-1 protein in patients with nasal polyps or sinonasal inverted papillomas

BACKGROUND

Nasal polyposis (NP) and sinonasal inverted papillomas (SIP) are considered benign lesions capable of recurrence or malignant transformation although not with the same prevalence. Since fluctuations of Caveolin-1 and Notch-1 proteins expression have been reported in many pathologies, the current study aimed to investigate their involvement in the epithelial transformation observed in SIPs compared to NP.

METHODS

Immunohistochemical expression of Caveolin-1 and Notch-1 proteins was assessed in 104 patients with sinonasal lesions (45 NP, 45 SIP and 14 NP with SIP), semiquantively (percentage times intensity). Proteins expression profiles were evaluated statistically for their correlation with patients demographic and clinicopathological variables (grade of dysplasia, inflammation, recurrence) as well as with markers of proliferation (Ki67) and apoptosis (7-AAD) as determined by flow cytometry analysis.

RESULTS

SIP lesions presented increased Caveolin-1 immunopositivity compared to NP (62.2%, vs 40.9%; p = 0.045). Cytoplasmic staining was observed only in epithelium's basal and suprabasal layers. Caveolin-1 positivity was not related to Ki67 expression, apoptosis, inflammation or dysplasia, eventhough 81.8% of highly immunopositive lesions were dysplastic (p = 0.03). Also, smokers presented significantly increased immunopositivy (p = 0.03). In contrast SIP lesions presented reduced Notch-1 expression compared to NP (68.9% vs 100%; p < 0.001). Dysplastic lesions presented low Notch-1 immunopositivity (p < 0.001). Enhancement of Notch-1 gene expression was also associated with inflammation.

CONCLUSIONS

The herein presented data suggest that the expression profiles of Caveolin-1 and Notch-1 proteins in sinonasal pathologies are distinctive and that could be explored as potential targets for the development of alternative therapeutic approaches.

Increased phosphorylation of eNOS in nasal polyps of chronic rhinosinusitis patients can be diminished by 1,8-cineol

INTRODUCTION

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a significant health problem, but the pathogenesis remains unclear to date. Nitric oxide (NO) has known airway modulating functions. Therefore, we investigated nitric oxide production to determine the role of eNOS in nasal polyps, with additional analysis of the effect of the monoterpene oxide 1,8-cineol on the possible regulation of eNOS signaling and thus NO production.

METHODS

We determined eNOS expression, as well as regulatory and effector proteins like NOSTRIN and CASP8, using whole genome microarray, immunohistochemistry and western blot. To evaluate the influence of 1,8-cineol on eNOS signaling, we examined tissue samples of nasal polyps of patients with CRSwNP incubated with 100 μM 1,8-cineol using quantitative real-time PCR, western blot and phosphorylation arrays.

RESULTS

Microarray analysis revealed an increased gene expression of eNOS (1.40-fold) as well as a decreased gene expression of NOSTRIN (0.53-fold) and CASP8 (0.44-fold) in nasal polyps. At the protein level, we detected 2.3-fold higher protein expression of eNOS and significant higher phosphorylation levels of eNOS in nasal polyps (19.7-fold, p ≤ 0.001) compared to inferior turbinates. Additionally, 1,8-cineol did not influence NOSTRIN and CASP8, but decreased the eNOS phosphorylation significantly (p ≤ 0.05).

DISCUSSION

Our study demonstrated for the first time that nasal polyps exhibit an increased phosphorylation of eNOS, which could be important for vascular permeability and the associated edema and elevated inflammation. Additionally, we detected that 1,8-cineol affects the eNOS phosphorylation significantly and thus its activation. This could be important to handle the elevated inflammation and edema formation by regulating the vascular permeability.