Expression of inducible nitric oxide synthase in antrochoanal polyps

Pheno-Endotyping Antrochoanal Nasal Polyposis

PURPOSE OF REVIEW

Antrochoanal polyps (ACPs) are benign polypoid lesions arising from the inner wall of the maxillary sinus and extending into the choana. Although the diagnosis and treatment strategies of ACP have changed since this entity was first described, the underlying pathogenic mechanism of APC is poorly understood. This article reviews the current knowledge of the etiology, inflammatory parameters, and microscopic findings of ACP.

RECENT FINDINGS

The inflammatory pattern of ACP appears to center around a neutrophilic inflammation T1-dominant endotype. Apart from the inflammatory component of ACP, at the microscopic level, the presence of tissue remodeling, mostly fibrin deposition and edema, and cysts in the epithelium and lamina propria has been described. Although the origin of this T1-dominant endotype immune response of ACPs is not entirely clear, it could be related to a lymphatic obstruction mechanism. This review serves to define a phenotype of ACP with potential endotypes based on the characteristics of the inflammatory parameters, microscopic findings, and hypotheses about the pathogenesis of ACP.

Expression Levels of Glutathione S-Transferase and Cytochrome P450 Isoenzymes in Nasal Polyp Tissue

Nasal polyps are benign sinonasal masses composed of eosinophils and extracellular edema. Pathogenesis of the polyp formation is unclear but several studies strongly suggest a correlation with infection, inflammation and allergy conditions. Our aim is to investigate the potential link between allergy and nasal polyp in tissue level. Nasal polyp group included 60 patients whose diagnosis was confirmed with biopsy and the control group included 38 healthy patients. Tissue sample of the control group was taken from inferior turbinate mucosa under local anesthesia and nasal polyp tissue was collected from functional endoscopic sinus surgery. The glutathione S-transferase (GST) and cytochrome P450 (CYP) isoenzyme expressions of the tissue samples were investigated under light microscopy and graded by a senior pathologist. GSTP1 protein expression was significantly higher in tissue samples from nasal polyp group compared to that of control group (p < 0.05). However, CYP1A1, GSTM1 and GSTA1 isoenzymes were not different between the two groups (p > 0.05). We have found that GSTP1 isoenzyme was elevated in nasal polyp tissue compared to the control. The increase in protein expression of GSTP1 might have occured as a tissue response to the increased oxidative stress thus suggesting a role of GSTP1 in polyp formation.

Is There any Possible Role of Neurotrophin 3 in the Pathogenesis of Antrochoanal Polyp?

Objective:

Antrochoanal polyp (ACP) is a benign soft tissue lesion arising from the inner wall of the maxillary sinus that extends into the nasal cavity and choana. Although it was first explained by Killian in 1906, the underlying pathogenesis has not been yet fully understood. Neurotrophins have been demonstrated to have a possible role in the pathogenesis of allergic rhinitis, idiopathic rhinitis and nasal polyps. To date any study has not investigated the function of neuronal inflammation and neurotrophins in the development of ACP. The objective of this study was to investigate the possible effect of neurotrophin-3 (NT-3) in ACP pathogenesis.

Method:

Twenty adult patients with ACP who underwent endoscopic sinus surgery in our department were included in the study group. The control group included 15 patients with concha bullosa of middle concha who underwent lateral excisional surgery. Nasal tissue NT-3 staining scores were evaluated using immunohistochemical methods. Blood NT-3 levels of both groups were evaluated by enzyme-linked immunosorbent assay (ELISA).

Results:

There were no statistically significant differences between these two groups regarding tissue NT-3 staining scores (p=0.843) and blood NT-3 levels (p=0.463). In addition, no statistically significant correlation has been observed between tissue NT-3 staining scores and blood NT-3 levels in both ACP (p=0.578) and control (p=0.359) group patients.

Conclusion:

NT-3-related neuronal inflammation does not seem to have any role in ACP pathogenesis.

Overexpression of Inducible Nitric Oxide Synthase in Allergic and Nonallergic Nasal Polyp

Sinonasal polyps are very common benign lesions of the nasal mucosa. Most of nasal polyps (NP) are idiopathic, and the pathophysiology of this disease is still incompletely understood. Nitric oxide (NO) is a reactive molecule generated by nitric oxide synthase (NOS). NO has been identified as an important mediator in airway function and pathogenesis of several respiratory system diseases. Histological and genetical expression of iNOS was detected to evaluate the role of NO in the pathogenesis of allergic (ANP) and nonallergic nasal polyps (NANP). Forty patients with nasal polyps (20 allergic and 20 nonallergic) were identified by history, clinical examination, and investigation. NPs were obtained from the middle turbinate (MT) during concha bullosa surgery. Twenty normal MT nasal tissues were taken as the control from patients undergoing concha bullosa surgery, without any evidence of allergy or inflammation. A nasal polyp specimen from each patient was subjected for immune-histochemical study followed by histological examination to detect the expression of iNOS. RT-PCR was used to evaluate the iNOS gene expression in isolated tissues. The expression of iNOS in both epithelial and stromal layers was greater in NP than in MT tissues. The ANP group showed more iNOS expression than those of the NANP group. The relative mRNA levels of iNOS gene were significantly higher in ANP (2.5-fold) compared to the normal (1.02-fold, P < 0.001) and NANP (1.5-fold, P < 0.01) groups. NP exhibited a significantly high expression of iNOS at both histological and genetical levels. NO might be an essential factor in the life history of NP. Further studies in a larger sample size are required to explain the probable mechanisms of NO in pathogenesis of NP.

Investigation of Human Papillomavirus (HPV) and Epstein-Barr Virus (EBV) in antrochoanal polyps

OBJECTIVES/HYPOTHESES

This study aimed to investigate the presence of HPV (HPV types 11 and 16) and EBV in antrochoanal polyps and to contribute to the current literature in this regard.

STUDY DESIGN

A case-control study.

METHODS

A total of 100 patients (including 43 patients undergoing surgery for antrochoanal polyp, 27 patients undergoing surgery for nasal polyp, and 30 patients undergoing surgery for hypertrophic inferior turbinate) were included in this study. DNA was isolated from formalin-fixed, paraffin-embedded samples with the aid of the Bioneer's AccuPrep Genomic DNA Extraction Kit. In the obtained genomic DNAs, while the detection of HPV DNA was performed using the nested-PCR method, the detection of HPV types 11/16 and EBV DNA was performed using the RT-PCR method.

RESULTS

The mean age of the patients with antrochoanal polyp was 26.7 ± 15.4 years (range 7-70). There were 20 (46.5%) women and 23 (53.5%) men in the antrochoanal polyp group. HPV DNA was positively detected using the nested-PCR method in 14 (32.6%) of the patients with antrochoanal polyp and in 3 (11.1%) of the patients with nasal polyp. HPV DNA was not detected in the hypertrophic inferior turbinate group (control group). There was a statistically significant difference between all groups in terms of HPV DNA positivity. In the antrochoanal polyp group, 2 patients had HPV 11 positivity and 12 patients had HPV 16 positivity. In the nasal polyp group, 1 patient had HPV 11 positivity and 2 patients had HPV 16 positivity. EBV DNA was positively detected in 16 (37.2%) of the patients with antrochoanal polyp, in 11 (40.7%) of the patients with nasal polyp and in 8 (26.7%) of the patients with hypertrophic inferior turbinate, respectively. There was no statistically significant difference between the groups in terms of EBV DNA positivity.

CONCLUSIONS

This study demonstrates that there is a need for further studies investigating the presence of viruses in antrochoanal polyps.

TNF-α and IL-1 β Cytokine Gene Polymorphism in Patients with Nasal Polyposis

Objective

Nasal Polyp (NP) is a benign mass of the paranasal sinuses that protrudes into the nasal cavity. The exact underlying pathogenesis is not known. In this study we aimed to determine the genetic susceptibility of NP formation in relation to TNF-α-308 and IL-1β-511 promoter region gene polymorphisms.

Methods

A total of 71 patients with NP with asthma (n=21) or without asthma (n=50) were taken as the study group, and 91 healthy volunteers were taken as the control group. Blood was gathered into EDTA-containing tubes, and patient DNA was extracted. The polymorphisms of the IL-β and TNF-α cytokine genes were analyzed using real time polymerase chain reaction.

Results

The GG genotype in the TNF-α-308 region and the CC genotype in the IL-1β-511 region were found to be risk factors for NP formation (OR: 9.2, p=0.007 and OR: 33.3, p=0.001, respectively). Regarding allelic frequencies, the G allele at the TNF-α-308 promoter region was a risk factor for NP formation (OR: 6.06, p<0.001).

Conclusion

TNF-α GG genotype in the -308 promoter region and the IL-1β CC genotype in the -511 region are genetic risk factors for NP formation.

Human Papillomavirus (HPV) Prevalence in Nasal and Antrochoanal Polyps and Association with Clinical Data

Objectives

The pathogenesis of sinonasal polyposis remains unclear, in spite of several investigative approaches. Antrochoanal polyps, a subgroup of sinonasal polyposis along with allergic- and chronic-inflammatory nasal polyps, mostly originate from the maxillary sinus and develop as a unilateral, pedunculated mass towards the nasopharynx. The human papillomavirus (HPV) is discussed as a possible causative and influencing factor in development and progression of sinonasal polyposis. This study aims to elucidate HPV frequency in nasal polyps and antrochoanal polyps.

Materials and Methods

Genomic DNA from 257 tissue specimens (166 nasal polyps, 39 antrochoanal polyps and 52 nasal turbinates) was subjected to three different established HPV- polymerase chain reaction assays, testing for 37 low- and high-risk HPV. In addition, immunohistochemical analyses for HPV16 were carried out, as well as immunohistochemistry and western blots of p16, a biomarker for HPV induced cancer.

Results

HPV-DNA was detected in 53.8% of antrochoanal polyps, 15.1% of nasal polyps, and 5.8% of nasal turbinates. HPV16 was the predominant type with a detection rate of 76% in nasal polyps and 62% in antrochoanal polyps. Immunohistochemically, HPV positive tissues stained positive for HPV16 antigens and p16 in epithelial cell layers. No significant p16 overexpression was traceable in antrochoanal polyps, nasal polyps and nasal turbinates by western blot. There was no correlation of HPV-status with sex, age, smoking, alcohol consumption or allergic background.

Conclusion

The present study shows a significant frequency of high-risk type HPV16 in antrochoanal polyps. Absence of oncogenic transformation or correlation of the HPV-status with clinical data suggests a latent superinfection, possibly because of anatomical proximity to the oropharynx.

Effect of glucocorticoids on nasal polyposis, with detection of inflammatory response by measurement of nitric oxide levels in nasal polyp tissue

OBJECTIVE

To investigate endoscopic staging, and nitric oxide levels in the polyp tissue, in patients with nasal polyposis undergoing glucocorticoid therapy.

METHODS

Nasal polyposis was evaluated using endoscopic staging and measurement of polyp tissue nitric oxide levels (chemiluminescence method). Forty-five nasal polyposis patients received either nasal therapy (n = 15), oral therapy (n = 15) or combined therapy (n = 15). Pre-treatment and post-treatment staging and nitric oxide levels were evaluated.

RESULTS

Endoscopic grading indicated significant post-treatment staging improvements in the oral (p = 0.016) and combined (p = 0.016) groups. Post-treatment staging differed significantly between the three groups (p = 0.041), with greater improvements in the oral and combined groups. All groups showed significantly lower post-treatment nitric oxide levels, compared with baseline, but post-treatment levels did not differ significantly between groups. A significant association was found between treatment response and nitric oxide level alteration.

CONCLUSION

This study demonstrates the favourable effects of glucocorticoids on nasal polyposis, and alteration in nitric oxide tissue levels post-treatment. Nitric oxide level in nasal polyp tissue could be an indicator of treatment response, and may aid surgical decision-making by detecting cases that probably will not respond to medical treatment.

The glutathione-S-transferase gene polymorphisms (Gstt1, Gstm1, and Gstp1) in patients with non-allergic nasal polyposis

There is an ongoing dilemma about the pathogenesis of nasal polyp (NP). The etiology of NP is multifactorial. Reactive oxygen species and oxidative stress are also suggested to be among the possible factors in NP development. Glutathione-S-transferase (GST) is one of the important detoxifying enzymes. It is not known whether GST plays any role in NP development. We aimed to investigate the relationship between GST subgroup (GSTT1, GSTM1, and GSTP1) polymorphisms, and NP development. Seventy-five patients with NP with or without asthma (NP with asthma: 22, NP without asthma: 53) were used as a study group. As much as 167 healthy individuals were involved as the control group. NP diagnosis was made by nasal endoscopy and paranasal sinus computed tomography (CT). NP was defined as the presence of endoscopically visible bilateral polyps originated from the middle meatus to the nasal cavity and affecting more than one paranasal sinus confirmed by CT. Blood was collected in EDTA-containing tubes and DNA was extracted from the leukocytes. The genotyping of polymorphisms of GSTT1, GSTM1, and GSTP1 were done using real time polymerase chain reaction. Chi-square (chi(2)) and Fisher's (F) exact tests were used for statistical evaluation. A 2-fold increased risk of NP could be found in individuals with the GSTT1 null genotype (OR = 2.03, 95% CI = 1.03-4.011). The distribution of GSTM1 null genotypes was not significantly different between the NP patients and controls and there was also no significance between the GSTP1 genotypes and NP. In conclusion, GST gene polymorphisms may be important in pathogenesis of NP. Additional studies which include larger study groups in different geographic localizations may be more useful to evaluate association with GST polymorphism and NP.

Does Helicobacter pylori play a role in etiology of nasal polyposis?

OBJECTIVE

Investigation of the possible relation between nasal polyposis (NP) and Helicobacter pylori (HP).

PATIENTS AND METHODS

Biopsy specimens of 25 patients with NP were evaluated. There were 16 men and 9 women enrolled in the study (NP) group. There were 10 men and 4 women in the control group. Campylobacter-like organism (CLO) test, immunohistochemical examination on nasal polyp tissue biopsy specimens and serological analysis were used for detecting HP.

RESULTS

There was only one (4%) positive NP case for CLO test. There were six cases in the study group with positive anti HP IgG test. Two control nasal mucosa were CLO positive. There were three cases in control group with positive anti HP IgG. There were no positive cases with positive anti IgM HP regarding both the study and the control groups. The immunohistochemical examination of the specimens taken from the patients with NP and control patients revealed that all patients were negative for HP. Positive CLO test and serologic test ratios were not statistically significant between NP and control groups.

CONCLUSION

The results of this study did not confirm other investigators. The suggested role of HP in the previous reports regarding NP may demonstrate transient occurrence of HP. It may not be treated as a possible etiological factor in NP.

Choanal polyp originating from the middle turbinate

Choanal polyps usually originate from the maxillary sinus. Unusual origins such as the sphenoid sinus, ethmoid sinus, nasal septum and hard and soft palate have been reported in the literature. Herein, we report a rare case of choanal polyp originating from the middle turbinate that was removed by an endoscopic surgery technique. The computed tomographic findings are described and the literature is reviewed.

Antrochoanal polyp: a transmission electron and light microscopic study

Antrochoanal polyp (ACP) is a soft tissue mass originating from the maxillary antrum, emerging from the ostium and extending to the choana through the nasal cavity. Our aim was to investigate the light microscopic and ultrastructural features of ACP and to compare these with nasal polyps originating from the middle meatus (MMP). Seven ACP and seven MMP specimens were evaluated by transmission electron microscopy (TEM) and light microscopy. TEM examination showed epithelial cells with intact cilia covering both polyps. In some MMP cases, degeneration of the epithelium associated with some cilia loss was noted. Goblet cell hyperplasia was more prominent in MMP cases. Degeneration and partial destruction of the endothelial cells of the blood vessels were common findings in ACP cases; however, in the MMP group, endothelial cells were mostly intact with a few aggregates of ribosomes, and intact cell junctions were noted. Light microscopic examination revealed that inflammatory cells in the ACP group were numerous. However, eosinophils were predominant in MMP cases. Squamous metaplasia of the surface epithelium was detected in five ACP cases, but in none of the MMP cases. Basement membrane thickening was detected in two cases of the ACP and in four cases of the MMP group. There was a statistically significant difference between the two groups for inflammatory cells, eosinophilic cell infiltration, squamous cell metaplasia, endothelial cell destruction and goblet cell metaplasia. In conclusion, the low number of eosinophils, the high number of other inflammatory cells, the normal appearing basement membrane and intact and normal surface epithelium may reveal that the etiology of ACP might arise from chronic inflammatory processes rather than allergy. The destruction of the endothelium may be considered as a further sign of chronic inflammation.