Production of 3-Nitrotyrosine in the Nasal Polyps and its Possible Role in the Pathogenesis and Recurrence
Atef Ragab Ahmed;
Abstract
Summary
N
asal polyps are benign proliferations of the nasal mucosa characterized by chronic inflammatory status (typically originating from the ethmoid epithelium). Histologic examinations have shown that nasal polyps consist of an epithelium covering a lamina propria with large infiltration of inflammatory cells.
Several lines of evidence have indicated that the diffusible free radical nitric oxide (NO) plays a crucial role in the pathophysiology of airway diseases and in the control of the airway inflammation. NO is produced from L-arginine by a group of three distinct isoforms of nitric oxide synthase (NOS). Two isoforms are continuously present and are termed constitutive NOS. The third isoform, named inducible NOS (iNOS) is not generally expressed in resting cells, but it may be induced by cytokines and microbial products to produce large quantities of NO for a long period of time.
In the airway inflammatory diseases, an excessive formation of NO caused by iNOS expression may cause tissue damage. This mainly originates from production of highly reacting nitrogen species by way of interactions of NO with reactive oxygen species (ROS).
Reaction of NO with superoxide anion generates the potent oxidant peroxynitrite, which may cause sever tissue injury. In addition, peroxynitrite nitrates tyrosine residues of proteins leading to formation of the stable product 3-nitrotyrosine (3NT), which is considered an indicator of oxidative damage in many diseases, including those of the airway.
This study aimed at comparing 3-NT production in nasal polyps patients and non-nasal polyp subjects in order to study its possible role in the pathogenesis of NP formation and recurrence, as an indicator of oxidative damage in this disease.
Specimens were collected under general anathesia from 50 patients with nasal polyps (study group), 30 patients of them with NP with no history of previous surgical removal (new cases) and the other 20 patients with NP with history of previous surgical removal (recurrent at least once). Control group specimen collected from 20 inferior turbinates of patients with no nasal polyps operated for another reason (septoplasty).
Biopsies from nasal polyps and inferior turbinates were examined histopathologically for eosinophilic count and epithelial damage.
There was found highly significant difference between the control group and the nasal polyps group (study group) regarding the eosinophil count (cells/HPF) and epithelial damage with significant higher eosinophilic count and significant higher epithelial damage in the nasal polyps group as compared to the control group.
There was found a significant difference between the patients with newly excised nasal polyps and patients with recurrent nasal polyps, with a higher eosinophilic count in the recurrent nasal polyps group as compared to the newly excised group.
There was found also a significant difference between the two groups as regard the epithelial damage score, with higher epithelial damage score in the recurrent nasal polyps group as compared to the newly excised group.
There was no significant correlation concerning eosiphilic count or the epithelial damage score in patients with single previous surgery and patients with two or more previous surgeries.
There was found that eosinophilic count has a sensitivity of 100% and a specificity of 100% in differentiating the nasal polyps group and the control group.
N
asal polyps are benign proliferations of the nasal mucosa characterized by chronic inflammatory status (typically originating from the ethmoid epithelium). Histologic examinations have shown that nasal polyps consist of an epithelium covering a lamina propria with large infiltration of inflammatory cells.
Several lines of evidence have indicated that the diffusible free radical nitric oxide (NO) plays a crucial role in the pathophysiology of airway diseases and in the control of the airway inflammation. NO is produced from L-arginine by a group of three distinct isoforms of nitric oxide synthase (NOS). Two isoforms are continuously present and are termed constitutive NOS. The third isoform, named inducible NOS (iNOS) is not generally expressed in resting cells, but it may be induced by cytokines and microbial products to produce large quantities of NO for a long period of time.
In the airway inflammatory diseases, an excessive formation of NO caused by iNOS expression may cause tissue damage. This mainly originates from production of highly reacting nitrogen species by way of interactions of NO with reactive oxygen species (ROS).
Reaction of NO with superoxide anion generates the potent oxidant peroxynitrite, which may cause sever tissue injury. In addition, peroxynitrite nitrates tyrosine residues of proteins leading to formation of the stable product 3-nitrotyrosine (3NT), which is considered an indicator of oxidative damage in many diseases, including those of the airway.
This study aimed at comparing 3-NT production in nasal polyps patients and non-nasal polyp subjects in order to study its possible role in the pathogenesis of NP formation and recurrence, as an indicator of oxidative damage in this disease.
Specimens were collected under general anathesia from 50 patients with nasal polyps (study group), 30 patients of them with NP with no history of previous surgical removal (new cases) and the other 20 patients with NP with history of previous surgical removal (recurrent at least once). Control group specimen collected from 20 inferior turbinates of patients with no nasal polyps operated for another reason (septoplasty).
Biopsies from nasal polyps and inferior turbinates were examined histopathologically for eosinophilic count and epithelial damage.
There was found highly significant difference between the control group and the nasal polyps group (study group) regarding the eosinophil count (cells/HPF) and epithelial damage with significant higher eosinophilic count and significant higher epithelial damage in the nasal polyps group as compared to the control group.
There was found a significant difference between the patients with newly excised nasal polyps and patients with recurrent nasal polyps, with a higher eosinophilic count in the recurrent nasal polyps group as compared to the newly excised group.
There was found also a significant difference between the two groups as regard the epithelial damage score, with higher epithelial damage score in the recurrent nasal polyps group as compared to the newly excised group.
There was no significant correlation concerning eosiphilic count or the epithelial damage score in patients with single previous surgery and patients with two or more previous surgeries.
There was found that eosinophilic count has a sensitivity of 100% and a specificity of 100% in differentiating the nasal polyps group and the control group.
Other data
| Title | Production of 3-Nitrotyrosine in the Nasal Polyps and its Possible Role in the Pathogenesis and Recurrence | Other Titles | تكوين مادة 3-نيتروتيروزين فى اللحميات الأنفية ودورها المحتمل فى نشأتها وإعادة | Authors | Atef Ragab Ahmed | Issue Date | 2016 |
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