No significant role for angiogenesis in nasal polyposis

Pericyte loss leads to microvessel remodeling and nasal polyp formation

BACKGROUND

Chronic rhinosinusitis (CRS) may be caused by increased vascular permeability and inflammatory cell leakage in the subepithelial tissue.

AIMS/OBJECTIVES

The aim of this study is to clarify the role of pericytes in tissue edema, microvessel dysfunction and vascular remodeling mechanisms in patients of CRS with nasal polyps (CRSwNP).

MATERIAL AND METHODS

A total of 63 tissue samples were collected, including 42 CRSwNP samples (22 eosinophilic CRSwNP (eCRSwNP) and 20 non-eosinophilic CRSwNP (non-eCRSwNP) samples) and 21 samples of CRS without nasal polyps (CRSsNP). The samples were stained by immunofluorescence to measure microvessel density (MVD) and microvessel pericyte coverage index (MPI).

RESULTS

We found that the albumin expression in the eCRSwNP group was significantly increased (p < .05). The MPI was significantly decreased (p <.05). There was a significant negative correlation between the MPI and the plasma albumin level (r=-0.82, p < .05). The MPI was negatively correlated with eosinophilic count (r=-0.77, p < .05). In the eCRSwNP group, the expressions of IL-4, Ang-1 and Ang-2 were increased compared with those in the control group.

CONCLUSIONS AND SIGNIFICANCE

Pericyte loss may induce microvessel dysfunction, affect the development of interstitial edema and eosinophilic exosmosis in eCRSwNP, and contribute to the formation and maintenance of nasal polyps.

On ciprofloxacin concentration in chronic rhinosinusitis

OBJECTIVE

Considering that all the evidence indicates that chronic rhinosinusitis without nasal polyps (CRSsNP) and chronic rhinosinusitis with nasal polyps (CRSwNP) are distinct entities, the aim of this study was to compare the concentrations obtained in plasma and in sinonasal mucosa with oral and nasal topical ciprofloxacin, in patients with and without nasal polyps, without evaluating the effectiveness of the use of an antibiotic.

METHODS

Prospective clinical study with single-blind randomization. The population consisted of patients with chronic rhinosinusitis with eligible for endonasal surgery, over 18 years old. It took place between January 2010 and December 2014. A single preoperative dose of ciprofloxacin (oral or nasal topic- spray, gel or drops) was given and samples of plasma and nasal mucosa (inferior turbinate, middle turbinate, ethmoid and maxillary sinus) were collected prior to surgery. The plasma and mucosal ciprofloxacin concentrations were assayed with high performance liquid chromatography (HPLC) with fluorescence detection (FD).

RESULTS

The oral ciprofloxacin achieved better mucosal concentrations but had a significant plasmatic expression in all patients. None of the topical formulations achieved measurable ciprofloxacin plasmatic levels. Among the topical formulations, the gel had the best mucosal results, despite the existence of polyposis.

Intraoperative bleeding during endoscopic sinus surgery and microvascular density of the nasal mucosa

PURPOSE

To evaluate the correlation between quality of the surgical field, intraoperative bleeding during endoscopic sinus surgery (ESS) and the density of microvasculature of the nasal mucosa.

MATERIAL/METHODS

Nasal mucosa of 30 patients, operated for chronic rhinosinusitis, was biopsied to assess expression of CD34 antigen on vascular endothelium. Quality of surgical field was evaluated with Fromm-Boezaart scale at mean arterial pressure (MAP) of 70-80 mmHg. If at this MAP surgical field quality was not satisfactory further reduction of hemodynamic parameters was performed until 'bloodless surgical field' (grade 2 or lower) was achieved. The rate of intraoperative bleeding was calculated from the ratio of total blood loss and the operative time. The extent of the disease was assessed according to computed tomography findings using Lund-Mackay staging system.

RESULTS

Significant positive correlation (Spearman correlation test; p<0.05) was found between CD34 antigen expression and quality of surgical field at MAP between 70 and 80 mmHg as well as the rate of intraoperative bleeding. More intense reduction of MAP was necessary to achieve 'bloodless surgical field' in patients with high CD34 expression than in those with moderate and low expression. Lund-Mackay score correlated with quality of surgical field but not with the rate of intraoperative bleeding.

CONCLUSION

During ESS, it is microvascular density of the nasal mucosa rather than the extent of the disease that contributes to the intensity of intraoperative bleeding, although both factors negatively influence the quality of surgical field.

Increased expression of angiogenin in nasal polyps

BACKGROUND

The aim of this study was to determine the expression and distribution of angiogenin in nasal polyps and to evaluate the implication of such expression with respect to the development of nasal polyps.

METHODS

Normal inferior turbinate mucosa was obtained from 20 patients undergoing surgery for augmentation rhinoplasty. Nasal polyp samples were obtained from 20 patients undergoing endoscopic sinus surgery for chronic polypoid rhinosinusitis. A semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR) was performed for angiogenin mRNA. Sections of nasal polyps were immunostained for localization of angiogenin and quantitatively analyzed using computer-based image analysis. Western blot analysis was performed.

RESULTS

Semiquantitative RT-PCR and Western blot analysis showed that angiogenin expression in nasal polyps was increased compared with that in normal nasal mucosa. Using immunohistochemical staining, moderate-to-high levels of angiogenin were mainly localized in the infiltrating inflammatory cells of nasal polyps and faint staining was found in normal nasal mucosa.

CONCLUSION

These results suggest that angiogenin may play a role in the pathophysiology of nasal polyps.

Hypoxia induces cysteine-rich 61, vascular endothelial growth factor, and interleukin-8 expressions in human nasal polyp fibroblasts: An implication of neutrophils in the pathogenesis of nasal polyposis

BACKGROUND

The purpose of this article was to elucidate the roles of neutrophils and angiogenesis factors in the pathogenesis of nasal polyposis. The effect of hypoxia on the expressions of angiogenesis factors as cysteine-rich 61 (Cyr61) and vascular endothelial growth factor (VEGF) and neutrophil chemoattractant as interleukin (IL)-8 in nasal polyp fibroblasts (NPFs), and the role of nuclear factor kappa B (NF-kappaB) in this reaction were investigated. The action of Cyr61 on the synthesis of VEGF and IL-8 in NPFs was also examined.

METHODS

Primary cultures of NPFs were established from nasal polyps (NPs). Productions of Cyr61, VEGF, and IL-8 by NPFs under hypoxia were detected by Western blot (Cyr61 and VEGF) or enzyme-linked immunosorbent assay (ELISA; IL-8). Immunohistochemical staining was used to examine the relation between fibroblastic expression of Cyr61 and neovascularization/neutrophil infiltration in NPs.

RESULTS

Western blot showed that the hypoxia inducer CoCl(2) stimulated Cyr61 synthesis in NPFs in a time-dependent manner, reaching a peak at 24 hours. Bay-117082 (a specific NF-kappaB inhibitor) attenuated the levels of Cyr61 stimulated by hypoxia. Cyr61 induced IL-8 secretion and VEGF synthesis by NPFs, as evidenced by Western blot and ELISA analysis. Bay-117082 abolished hypoxia-stimulated IL-8 and VEGF synthesis, whereas Cyr61 restored the stimulative effect of hypoxia readily. Immunohistochemical staining revealed the presence of Cyr61 and IL-8 in NPFs. Neutrophils and capillaries aggregating around these NPFs were frequently found.

CONCLUSION

Under hypoxia, NPFs contribute to NP propagation by expressing Cyr61, which subsequently stimulates VEGF and IL-8 production, leading to angiogenesis and activating neutrophil infiltration in NPs.

Pathophysiology of nasal polyposis: the role of desmosomal junctions

BACKGROUND

Many mucosal inflammatory conditions are associated with alterations in epithelial intercellular junctions and barrier function; however, little is known about the role of intercellular junctions in inflammatory diseases of the upper airways. In this study, we examined nasal polyps for altered intercellular junctions and protein expression.

METHODS

Biopsy specimens of nasal polyps and normal tissue were obtained intraoperatively from 11 patients and 6 controls. Tissue was analyzed for expression of intercellular junctional proteins by immunofluorescence. In parallel, cultured human bronchial epithelial (HBE) cells were treated with tumor necrosis factor (TNF) alpha, interferon (IFN) gamma, and IL-13 to simulate inflammatory conditions followed by assessment for changes in junctional proteins by immunofluorescence and Western blot.

RESULTS

Of the intercellular junctional proteins analyzed, including proteins comprising tight and adherens junctions, the only alterations observed were in desmosomal proteins in nasal polyp epithelium compared with normal controls. Specifically, expression of desmosomal proteins DSG2 and DSG3 were significantly decreased in polyps versus controls (0.53 pixel/microm2 versus 1.09 pixel/microm2 [p = 0.009], and 0.29 pixel/microm2 versus 1.11 pixel/microm2 [p = 0.0078], respectively). In vitro experiments involving exposure of cultured HBE cells with inflammatory cytokines revealed that TNF-alpha treatment resulted in internalization and decreased expression of DSG2 by immunofluorescence and Western blotting. Treatment with IFN-gamma resulted in increased expression of DSG2 and evidence of protein cleavage by Western blot. IL-13 exposure resulted in down-regulation of DSG2 expression and evidence of protein cleavage.

CONCLUSION

These results indicate that nasal polyps express decreased levels of DSG2 and DSG3 components of desmosomal junctions. This is likely linked to the mucosal inflammatory response. Exposure of a respiratory cell line to Th1/Th2 cytokines results in similar expressional alterations in DSG2, suggesting protein internalization and cleavage. We speculate that weakened desmosomal junctions in nasal mucosa secondary to inflammatory cytokines may contribute to the formation of nasal polyposis.