Comparison of arginase isoform expression in patients with different subtypes of chronic rhinosinusitis

Nitric oxide synthase-2 (CCTTT)n polymorphism is associated with local gene expression and clinical manifestations in patients with chronic rhinosinusitis

Introduction

Nitric oxide (NO) is synthesized through NO synthase (NOS). The proximal NOS2 gene promoter contains the pentanucleotide CCTTT repeat polymorphism. We examined whether CCTTT repeats are associated with NOS2 expression in the sinonasal tissues and clinical manifestations in patients with chronic rhinosinusitis.

Methods

Mucosal specimens were obtained from the ethmoid sinus and inferior turbinate of 30 eosinophilic chronic rhinosinusitis (ECRS) and 28 non-ECRS patients. CCTTT repeats were classified into short alleles (S), with less than or equal to 14, and long alleles (L), with more than 14. The subjects were classified into the L/S + L/L and S/S groups.

Results

In ECRS, the NOS2 mRNA levels of the ethmoid sinus mucosa were significantly higher in the L/S + L/L group than in the S/S group (median, 1.66 and 0.77, respectively). On the ther hand, ECRS patients showed no significant difference in the NOS2 mRNA level of the inferior turbinate between the L/S + L/L group and the S/S group (median, 0.63 and 0.88, respectively). In ECRS, preoperative SNOT-22 were significantly higher in the L/S + L/L group than in the S/S group, whereas the former group showed a lower postoperative recurrence risk.

Conclusion

CCTTT repeat polymorphism in the NOS2 promotor gene may be a useful indicator to evaluate ECRS severity and prognosis.

The Functional Diversity of Nitric Oxide Synthase Isoforms in Human Nose and Paranasal Sinuses: Contrasting Pathophysiological Aspects in Nasal Allergy and Chronic Rhinosinusitis

The human paranasal sinuses are the major source of intrinsic nitric oxide (NO) production in the human airway. NO plays several roles in the maintenance of physiological homeostasis and the regulation of airway inflammation through the expression of three NO synthase (NOS) isoforms. Measuring NO levels can contribute to the diagnosis and assessment of allergic rhinitis (AR) and chronic rhinosinusitis (CRS). In symptomatic AR patients, pro-inflammatory cytokines upregulate the expression of inducible NOS (iNOS) in the inferior turbinate. Excessive amounts of NO cause oxidative damage to cellular components, leading to the deposition of cytotoxic substances. CRS phenotype and endotype classifications have provided insights into modern treatment strategies. Analyses of the production of sinus NO and its metabolites revealed pathobiological diversity that can be exploited for useful biomarkers. Measuring nasal NO based on different NOS activities is a potent tool for specific interventions targeting molecular pathways underlying CRS endotype-specific inflammation. We provide a comprehensive review of the functional diversity of NOS isoforms in the human sinonasal system in relation to these two major nasal disorders' pathologies. The regulatory mechanisms of NOS expression associated with the substrate bioavailability indicate the involvement of both type 1 and type 2 immune responses.

Relationship between arginase genes polymorphisms and preschool wheezing phenotypes

BACKGROUND

The association between arginase I (ARG1) and arginase II (ARG2) genes and asthma has been reported in previous studies, but associations between polymorphisms in ARG genes and preschool wheezing (PSW) phenotypes are still unknown.

OBJECTIVE

To examine the association between genetic variation in ARG1 and ARG2 genes and PSW phenotypes.

METHODS

We enrolled 83 patients and 86 healthy controls. The patient group included two subgroups: episodic wheezing (EW) (n = 42, median age 41 months) and multiple-trigger wheezing (MW) (n = 41, median age 39 months). We genotyped six single nucleotide polymorphisms (SNPs) in ARG1 and six SNPs in ARG2. Eighteen haplotypes for ARG1 and 31 haplotypes for ARG2 were constituted, and the distributions of SNPs and haplotypes in patients and controls were analyzed.

RESULTS

The frequency of the homozygote cytosine-cytosine (CC) genotype of ARG1 rs2781667T>C SNP and the ARG1 haplotype 4 in the MW group was significantly higher than the EW group (p = .002; odd ratios [OR]: 5.25; confidence interval [CI]: 1.9-14.51 and p < .001; OR: 7.77; CI: 2.54-23.74, respectively). The frequency of the ARG1 haplotype 5 was significantly higher but the frequency of ARG1 haplotype 9 was significantly lower in the all patients than in the healty controls (p = .019; OR: 10.34; CI: 1.28-83.53 and p = .015; OR: 0.093; CI:0.01-0.74, respectively). The frequency of the ARG1 haplotype 2 was significantly higher in the EW group than in the MW group (p = .014; OR: 5.68; CI: 1.48-21.8).

CONCLUSION

Variations in ARG1 may potentially be related to phenotypes and risk of PSW.

Arginase Isoform Expression in Chronic Rhinosinusitis

Nitric oxide (NO) has emerged as an important regulator of upper airway inflammation, mainly as part of the local naso-sinusal defense mechanisms. Increased arginase activity can reduce NO levels by decreasing the availability of its precursor, L-arginine. Chronic rhinosinusitis (CRS) has been associated with low levels of nasal nitric oxide (nNO). Thus, the present study investigates the activity of arginase I (ARG1) and II (ARG2) in CRS and its possible involvement in the pathogenesis of this disease. Under endoscopic view, tissue samples of pathologic (n = 36) and normal (n = 29) rhinosinusal mucosa were collected. Arginase I and II mRNA levels were measured using real-time PCR. Our results showed low arginase I activity in all samples. The levels of ARG2 were significantly higher in patients with chronic rhinosinusitis compared to the control group (fold regulation (FR) 2.22 ± 0.42 vs. 1.31 ± 0.21, p = 0.016). Increased ARG2 expression was found in patients with CRS without nasal polyposis (FR 3.14 ± 1.16 vs. 1.31 ± 0.21, p = 0.0175), in non-allergic CRS (FR 2.55 ± 0.52 vs. 1.31 ± 0.21, p = 0.005), and non-asthmatic CRS (FR 2.42 ± 0.57 vs. 1.31 ± 0.21, p = 0.028). These findings suggest that the upregulation of ARG2 may play a role in the pathology of a distinctive phenotype of CRS.

IL-5 and IL-6 are increased in the frontal recess of eosinophilic chronic rhinosinusitis patients

Background

Eosinophilic chronic frontal sinusitis is difficult to treat compared with non-eosinophilic sinusitis because of recurring inflammation and polyp formation in the frontal recess after the post-operative follow-up period. Studying inflammatory mediators in the frontal recess of eosinophilic chronic rhinosinusitis (ECRS) patients and non-eosinophilic chronic rhinosinusitis (non-ECRS) patients may lead to a better understanding of the pathogenesis of chronic frontal sinusitis.

Methods

Homogenates of sinonasal mucosa from 20 non-ECRS patients and 36 ECRS patients were measured for levels of transforming growth factor (TGF)-β, interleukin (IL)-5, IL-6, and inducible nitric oxide synthase (iNOS) using real-time RT-PCR and TaqMan gene expression assays. Sinonasal mucosal specimens were obtained from the frontal recess, ethmoid sinus, and nasal polyp separately.

Results

The expression of IL-5 was significantly elevated in all sinonasal regions tested in the ECRS group, but absent in non-ECRS patients. Furthermore, the ECRS patients showed significantly increased levels of IL-5 in the frontal recess mucosa compared with ethmoid sinus mucosa. IL-6 was also significantly increased in the frontal recess mucosa compared with ethmoid sinus mucosa and nasal polyps in these patients. There were no significant differences in the levels of TGF-β or iNOS between the ECRS and non-ECRS groups in any sinonasal region tested.

Conclusions

This study is the first to characterize the cytokine milieu in the frontal recess of ECRS patients. We should keep these cytokine profiles in mind when we treat ECRS patients with frontal sinusitis.