Reduced nitric oxide in sinus epithelium of patients with radiologic maxillary sinusitis and sepsis

Diagnostic value and underlying mechanism of nasal nitric oxide in eosinophilic chronic rhinosinusitis with nasal polyps

PURPOSE

Nitric oxide (NO) is an important messenger molecule widely present in the human body. However, the role of nasal NO (nNO) in eosinophilic chronic rhinosinusitis with nasal polyps (Eos CRSwNP) remain unclear. This study aimed to investigate the diagnostic value and underlying mechanism of nNO in Eos CRSwNP.

METHODS

The medical records of 84 non-Eos CRSwNP patients, 55 Eos CRSwNP patients, and 37 control subjects were retrospectively reviewed. The diagnostic value of nNO for Eos CRSwNP was assessed. The expression of inducible nitric oxide synthase (iNOS), endothelial nitric oxide synthase (eNOS), and tight junctions (TJs) components claudin-1, occludin, and ZO-1 was detected in the nasal polyps. Primary human nasal epithelial cells (HNECs) were co-treated with eNOS inhibitor (L-NAME) or Akt inhibitor (MK-2206), interleukin (IL)-13, and dexamethasone (Dex). The level of NO and the expression of TJs and Akt/eNOS pathways were examined.

RESULTS

The nNO levels of the CRSwNP group were significantly lower than those of the control group. Compared with the non-Eos CRSwNP group, the Eos CRSwNP group showed higher nNO level. The combination of nNO level, eosinophilic percentage, and posterior ethmoid score had a better predictive value for Eos CRSwNP (AUC = 0.855). The expression of iNOS, eNOS, and p-eNOS was higher in the CRSwNP groups than in the control group, and p-eNOS expression was higher in the Eos CRSwNP group than in the non-Eos CRSwNP group. The expression of TJs was lower in the Eos CRSwNP group than in the non-Eos CRSwNP and control group. IL-13 decreased TJ expression in HNECs, while Dex promoted Akt and eNOS phosphorylation, NO production and TJ expression. Furthermore, these effects of Dex were inhibited by L-NAME and MK-2206 in HNECs.

CONCLUSION

nNO may have a high diagnostic value in Eos CRSwNP, and Akt/eNOS pathway may promote the generation of NO to protect TJs. NO may have a potentially important role in the diagnosis and treatment of Eos CRSwNP.

Epidemiological Characteristics, Pathogenesis and Clinical Implications of Sinusitis in the Era of COVID-19: A Narrative Review

Sinusitis is a common condition with various forms and different etiologies. In the era of COVID-19, a large number of studies covered the association between sinusitis and COVID-19, while others reported the impact of COVID-19 on the development of acute invasive fungal rhinosinusitis (AIFR), together with the most commonly associated predisposing factors. Fungal sinusitis, particularly AIFR, can be life-threatening. It is important to dissect this association and improve current evidence and management. Therefore, we conducted this literature review to highlight the association between COVID-19 and sinusitis based on evidence from the available studies in the literature. Evidence shows that chronic sinusitis might have a negative impact on COVID-19 outcomes. However, current results are conflicting, and further studies are needed. On the other hand, COVID-19 can also cause olfactory dysfunction, which is usually temporary. In addition, we found several studies that indicated the association between COVID-19 and AIFR. The condition is usually associated with severe morbidities, as affected patients are usually immunocompromised, including those with uncontrolled diabetes, malignancy, immunosuppression, AIDS, the administration of chemotherapy and other immunosuppressive drugs, and COVID-19.

S-Nitrosoglutathione Reduces the Density of Staphylococcus aureus Biofilms Established on Human Airway Epithelial Cells

Patients with chronic rhinosinusitis (CRS) often show persistent colonization by bacteria in the form of biofilms which are resistant to antibiotic treatment. One of the most commonly isolated bacteria in CRS is Staphylococcus aureus (S. aureus). Nitric oxide (NO) is a potent antimicrobial agent and disperses biofilms efficiently. We hypothesized that S-nitrosoglutathione (GSNO), an endogenous NO carrier/donor, synergizes with gentamicin to disperse and reduce the bacterial biofilm density. We prepared GSNO formulations which are stable up to 12 months at room temperature and show the maximum amount of NO release within 1 h. We examined the effects of this GSNO formulation on the S. aureus biofilm established on the apical surface of the mucociliary-differentiated airway epithelial cell cultures regenerated from airway basal (stem) cells from cystic fibrosis (CF) and CRS patients. We demonstrate that for CF cells, which are defective in producing NO, treatment with GSNO at 100 μM increased the NO levels on the apical surface and reduced the biofilm bacterial density by 2 log units without stimulating pro-inflammatory effects or inducing epithelial cell death. In combination with gentamicin, GSNO further enhanced the killing of biofilm bacteria. Compared to placebo, GSNO significantly increased the ciliary beat frequency (CBF) in both infected and uninfected CF cell cultures. The combination of GSNO and gentamicin also reduced the bacterial density of biofilms grown on sinonasal epithelial cells from CRS patients and improved the CBF. These findings demonstrate that GSNO in combination with gentamicin may effectively reduce the density of biofilm bacteria in CRS patients. GSNO treatment may also enhance the mucociliary clearance by improving the CBF.

Anatomical Characteristics of the Accessory Maxillary Ostium in Three-Dimensional Analysis

Background and Objectives: The accessory maxillary ostium (AMO) can interfere with ventilation and drainage of the maxillary sinus, and therefore the importance of evaluating the anatomical features of the AMO has been emphasized. This study aimed to evaluate anatomical characteristics of the AMO together with the natural ostium (NO) using three-dimensional (3D) analysis and to assess the relationship between the AMO and maxillary sinus pathologies. Materials and Methods: This retrospective study included 394 sinuses in 197 patients. Using 3D computed tomography images, the prevalence of the AMO and concurrent sinus pathologies were examined. For patients with an AMO, 3D spatial positions of the AMO and NO related to adjacent anatomic structures and dimensions of the AMO and NO were evaluated. Results: A total of 84 sinuses showed single or multiple AMO, with a prevalence of 21.3%. The AMO was located superiorly by 30.1 mm from the maxillary sinus floor, inferiorly by 1.3 mm from the orbital floor, and posteriorly by 22.4 mm from the anterior sinus wall. The AMO was located 5.4 mm posteriorly and 0.7 mm inferiorly from the NO. On the same coronal plane as the NO or AMO, height from the maxillary sinus floor to the NO and AMO ranged from 19.4 to 45.8 mm and 14.5 mm to 41.9 mm, respectively. The mean horizontal and vertical dimensions were 5.9 mm and 4.6 mm for the NO and 2.8 mm and 3.0 mm for the AMO. We detected a significant association between the presence of the AMO and the mucosal thickening (p = 0.029). Conclusions: The results of this study suggest that, although the AMO and NO are mostly located in positions that do not limit sinus-related surgeries, such as maxillary sinus floor augmentation, the AMO and NO are also found in lower positions, which may be a detriment to the postoperative physiological function of the maxillary sinus and affect treatment outcomes.

Defenses of multidrug resistant pathogens against reactive nitrogen species produced in infected hosts

Bacterial pathogens have sophisticated systems that allow them to survive in hosts in which innate immunity is the frontline of defense. One of the substances produced by infected hosts is nitric oxide (NO) that together with its derived species leads to the so-called nitrosative stress, which has antimicrobial properties. In this review, we summarize the current knowledge on targets and protective systems that bacteria have to survive host-generated nitrosative stress. We focus on bacterial pathogens that pose serious health concerns due to the growing increase in resistance to currently available antimicrobials. We describe the role of nitrosative stress as a weapon for pathogen eradication, the detoxification enzymes, protein/DNA repair systems and metabolic strategies that contribute to limiting NO damage and ultimately allow survival of the pathogen in the host. Additionally, this systematization highlights the lack of available data for some of the most important human pathogens, a gap that urgently needs to be addressed.

Recent Developments in Nitric Oxide Donors and Delivery for Antimicrobial and Anti-Biofilm Applications

The use of nitric oxide (NO) is emerging as a promising, novel approach for the treatment of antibiotic resistant bacteria and biofilm infections. Depending on the concentration, NO can induce biofilm dispersal, increase bacteria susceptibility to antibiotic treatment, and induce cell damage or cell death via the formation of reactive oxygen or reactive nitrogen species. The use of NO is, however, limited by its reactivity, which can affect NO delivery to its target site and result in off-target effects. To overcome these issues, and enable spatial or temporal control over NO release, various strategies for the design of NO-releasing materials, including the incorporation of photo-activable, charge-switchable, or bacteria-targeting groups, have been developed. Other strategies have focused on increased NO storage and delivery by encapsulation or conjugation of NO donors within a single polymeric framework. This review compiles recent developments in NO drugs and NO-releasing materials designed for applications in antimicrobial or anti-biofilm treatment and discusses limitations and variability in biological responses in response to the use of NO for bacterial eradiation.

Nitric Oxide Is Locally Produced in the Human Middle Ear and Is Reduced by Acquired Cholesteatoma

OBJECTIVE

To find out if nitric oxide (NO) can be locally produced in the middle ear and if chronic otitis media (COM) and acquired cholesteatoma affect the production.

DESIGN

Case-control study.

SETTING

Two tertiary-referral hospitals.

PATIENTS

Gaseous NO from 11 patients with unilateral perforations or grommet openings was measured with chemiluminescence. Middle ear mucosa from 48 patients with COM and 26 patients with cholesteatoma was investigated.

MAIN OUTCOME MEASURES

Detection of NO. Expression of nitric oxide synthase (NOS) mRNA, in mucosa from COM, cholesteatoma and healthy controls, quantified using polymerase chain reaction.

RESULTS

The gaseous NO from ears with a unilateral tympanic membrane perforation or a grommet was higher (9 ± 3 ppb, n = 11) than among the controls (4 ± 1 ppb, n = 11, p = 0.04). Lower levels of eNOS (2.64 ± 0.86 mol/100,000 mol ACTB) were detected in the pooled samples from the COM group (n = 48), compared with the control group (140.48 ± 92 mol/100,000 mol ACTB, n = 45, p = 0.010). In the cholesteatoma group (n = 26), a lower expression of nNOS (5.78 × 10-6 ± 1.13 × 10-6 ΔCt) was found in comparison with the controls (1.23 × 10-4 ± 3.18 × 10-5 ΔCt, n = 15, p = 0.011).

CONCLUSIONS

NO is likely a natural and permanent part of the gas mixture in the human middle ear. The presence of NOS enzymes in the middle ear mucosa indicates an ongoing NO production and the reduction of NOS in ears with cholesteatoma, and pooled samples from ears with COM, suggest a role for locally produced NO in middle ear disease.

Nasal Nitric Oxide in the Upper Airway Inflammatory Diseases

Exhaled nitric oxide (eNO) from the lower respiratory tract is used commonly in diagnosis and treatment monitoring of asthma patients. However, nasal nitric oxide (nNO) has not been widely used in patients with upper airway inflammatory diseases due to its lack of standardized measurement methods. Nasal nitric oxide is produced mainly by the paranasal sinus mucosa and partially by the nasal mucosa and increases with inflammation. Nasal nitric oxide not only locally supports the defensive mechanism of the upper respiratory tract, but also remotely controls pulmonary function by acting as an aerocrine. Nasal NO can be affected by various physiologic and pathologic factors of the upper respiratory tract. This article will review the origin of nNO, its function, various measurement methods, and difference in presentation among upper respiratory tract inflammatory diseases such as allergic rhinitis, upper respiratory tract infection, nasal polyp, rhinosinusitis, primary ciliary dyskinesia, cystic fibrosis, Young’s syndrome, diffuse panbronchiolitis, empty nose syndrome, and obstructive sleep apnea. Future studies should identify the mechanism of action of nNO in various upper respiratory tract inflammatory diseases and obtain highly reproducible normal values of nNO based on a standardized measurement method with a deeper understanding of factors affecting nNO. Then, nNO will be useful for more rapid and simpler diagnosis of various upper respiratory tract diseases and for monitoring their treatment.

Estimating COVID-19 Infection and Severity Risks in Patients with Chronic Rhinosinusitis: A Korean Nationwide Cohort Study

Background

Basic studies suggest that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can affect chronic rhinosinusitis (CRS), but there is unclear real-world evidence regarding the association of underlying CRS with the risk for SARS-CoV-2 infection and severe coronavirus disease 19 (COVID-19).

Objective

We aimed to determine whether CRS is associated with increased risk for SARS-CoV-2 infection and severe COVID-19.

Methods

Altogether, 219,959 adult patients who tested for SARS-CoV-2 in South Korea from January 1 to May 15, 2020 (excluding self-referral) were identified in this nested case-control study with propensity score matching. Data on SARS-CoV-2 test results and COVID-19 worsened outcomes (ie, the need for oxygen therapy, intensive care, or mechanical ventilation, and death) were obtained from the Health Insurance Review and Assessment Service of Korea.

Results

In this matched cohort, 380 of 12,217 patients with CRS (3.1%) tested positive for SARS-CoV-2 infection, compared with 310 patients without CRS (2.5%; adjusted odds ratio = 1.22; 95% confidence interval, 1.04-1.42). Moreover, 60 of 286 COVID-19 patients with CRS (21.0%) had severe COVID-19 outcomes, compared with 38 without CRS (13.3%; adjusted odds ratio = 1.71; 95% confidence interval, 1.09-2.71). Subgroup analysis identified that CRS patients with an absence of nasal polyps, prior intranasal corticosteroid use, or nonatopic type had a greater risk for SARS-CoV-2 infection and severe COVID-19 outcomes.

Conclusions

In patients with CRS, prior intranasal corticosteroid use, the absence of nasal polyps, or nonatopic type was associated with increased risk for SARS-CoV-2 infection and severe COVID-19 in the Korean nationwide cohort. Clinicians should be cautious in determining prognosis and care for patients with CRS amid the COVID-19 pandemic.

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.

Recent advances in the diagnosis of allergic rhinitis

INTRODUCTION

Allergic rhinitis (AR) is a disorder with high prevalence worldwide. Identification of clinically relevant allergens is the key step for the diagnosis, allergen avoidance and allergen specific immunotherapy for AR. Areas covered: With the new findings of mechanisms of AR and the development of technology, much progress has been achieved in the diagnosis of AR recently. We review the recent advances about local IgE, in vivo and in vitro tests, cytological diagnosis and nitric oxide (NO) in the diagnosis of AR. Expert commentary: AR is traditionally diagnosed with the combined evaluation of history and allergen sensitization by in vivo skin prick tests and in vitro allergen specific IgE in serum, to confirm the correlation between clinical history and potential allergens. Nasal provocation test and local IgE measurement can be used to diagnose local AR. Allergen microarray has the ability to detect more potential allergens. Basophil activation and mast cell activation tests can be used in allergen diagnosis and to modify the response to immunotherapy, while cytological diagnosis is useful in the differential diagnosis of AR and non-AR. Nasal NO has been confirmed to be an optimal biomarker to discriminate between AR and non-AR.

What is the evidence for genetics in chronic rhinosinusitis?

PURPOSE OF REVIEW

To perform analysis of evidence in current literature on the topic of genetics and chronic rhinosinusitis (CRS), with a particular focus on recent findings in the cystic fibrosis transmembrane regulator (CFTR), genes associated with primary ciliary dyskinesia, and taste receptor T2R38. Other genes that have been found to have association with CRS are also presented and discussed.

RECENT FINDINGS

Recent studies in CFTR and CRS research have investigated possible CFTR-potentiators for treatment of refractory CRS. The T2R38 gene has been shown to be applicable in the clinical setting with a testable phenotype and may have a role in the prognosis and influencing management strategies of CRS patients. Many genes of the immune system have been studied, with genome-wide association studies and candidate-gene approaches identifying new associations that will need replication and further elucidation.

SUMMARY

CRS is a multifactorial disease, with strong evidence of a genetic component in its pathophysiology for some cases. Currently, there are over 70 genes that have been genetically associated with CRS in the past 15 years. Future investigations into genetic causes and predispositions of CRS may allow for improved prognostication and development of disease-prevention strategies as well as novel therapeutic targets.

Nitric oxide synthase 2 enhances the survival of mice during Salmonella Typhimurium infection-induced sepsis by increasing reactive oxygen species, inflammatory cytokines and recruitment of neutrophils to the peritoneal cavity

Sepsis, a leading cause of death in intensive care units, is primarily caused due to an exaggerated immune response. The hyperactive inflammatory response mediated by immune cells against infectious organisms and their toxins results in host cell death and tissue damage, the hallmarks of septic shock. Therefore, molecules that modulate inflammatory responses are attractive therapeutic targets for sepsis. Nitric oxide (NO) is a signaling molecule, which is implicated in regulating diverse immune functions. Although, the protective roles of NO in infectious diseases are well documented, its importance in sepsis is controversial. In the present study, the effects of intra-peritoneal injection of mice with Salmonella Typhimurium, a Gram-negative intracellular pathogen, were studied which leads to a rapid upregulation of serum cytokines and infiltration of neutrophils to the peritoneal cavity. Surprisingly, the induction of inflammatory cytokines and chemokines, e.g. IL6 and CCL2, and the infiltration of neutrophils into the peritoneal cavity are mitigated in mice lacking Nitric oxide synthase 2 (NOS2). The reduced inflammatory response in Nos2^-/- mice is accompanied by greater bacterial burden in the peritoneal cavity, lower thymic atrophy, higher liver damage and cardiovascular dysfunction followed by decreased survival. However, no significant differences are observed in other responses between C57BL/6 wild type (WT) and Nos2^-/- mice: induction of glucocorticoids, phagocytic ability and apoptosis of peritoneal cells. This study clearly highlights the NOS2-dependent and -independent responses in this mouse model of peritonitis induced sepsis. Importantly, pre-treatment of Nos2^-/- mice with DETA-NO, a NO donor, upon infection, restores neutrophil recruitment, reduces bacterial numbers in the peritoneal cavity, improves liver and cardio-vascular function and enhances survival. Interestingly, DETA-NO treatment does not significantly increase the survival of infected WT mice. The implications of these results and the complex roles of NO as a target molecule during sepsis are discussed.

Role of Exhaled Nasal Nitric Oxide in Distinguishing between Chronic Rhinosinusitis with and without Nasal Polyps

Background

Chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP) and CRS without nasal polyps (CRSsNP) nasal polyps is a global health concern. Several clinical biomarkers, such as inhaled carbon monoxide and exhaled nitric oxide (NO), have been studied to assess the presence and degree of inflammation in the airway mucosa.

Objective

To evaluate the clinical application of exhaled nasal NO (nNO) in distinguishing between CRSwNP and CRSsNP in consideration of the atopic status of patients.

Methods

Eighty-eight patients with CRS and 20 healthy volunteers were recruited for this study. The exhaled nNO level was measured by using a hand-held device. Nasal endoscopy (with Lund-Mackay scoring of CRS) and sinus computed tomographies (CT) were used to evaluate the nasal cavity and sinuses of the subjects. Atopic status was confirmed by using skin prick tests (SPTs).

Results

The mean ∓ standard deviation (SD) levels of nNO in patients with CRSsNP were significantly higher than those in patients with CRSwNP (591 ∓ 153 ppb versus 360 ∓ 181 ppb, p <0.001), whereas patients with CRS exhibited lower levels of nNO compared with the control subjects (449 ∓ 204 ppb versus 881 ∓ 161 ppb, p <0.001). Patients with atopy and with and without nasal polyps exhibited significantly higher levels of nNO compared with patients without atopy (atopic CRSsNP versus nonatopic CRSsNP, 734 ∓ 220 ppb versus 503 ∓ 92 ppb [p <0.001]; atopic CRSwNP versus nonatopic CRSwNP, 518 ∓ 161 ppb versus 299 ∓ 150 ppb [p <0.001]). The levels of nNO were negatively correlated with the Lund-Mackay scores in both atopic (r = -0.45; p = 0.016) and nonatopic (r = -0.600; p <0.001) patients with CRS. Receiver operating characteristic curves differentiated patients as CRSwNP, CRSsNP, and healthy controls, and in atopic and nonatopic subgroups, with acceptable sensitivity and specificity (>70 to 90%).

Conclusion

Exhaled nNO levels can be used to distinguish between patients with CRSwNP and patients with CRSsNP. However, the atopic status of the patient influenced the use of nNO as a diagnostic or monitoring biomarker in CRS.

Combined measurements of fractional exhaled nitric oxide and nasal nitric oxide levels for assessing upper airway diseases in asthmatic patients

BACKGROUND

Despite the close linkage between rhinitis, chronic rhinosinusitis (CRS) and asthma, relevant biomarkers of both upper and lower airway inflammation are rare.

METHODS

Patients with asthma (without upper airway disease [UAD; n = 24], with rhinitis [n = 25], CRS [n = 24], and nasal polyps [n = 2]), isolated rhinitis (n = 13), isolated CRS (n = 13), and 10 healthy controls were prospectively recruited. Fractional exhaled nitric oxide (NO) levels at 50 mL/s (FeNO₅₀), nasal NO levels, Lund-Macay-scores of sinus computed tomography and an asthma control questionnaire (ACQ) were evaluated.

RESULTS

Asthma was associated with higher FeNO₅₀ levels irrespective of the UAD category. FeNO₅₀ levels were higher in asthmatics with CRS (median: 54.0 ppb) than those with rhinitis (35.2 ppb, p = 0.02) and those without UAD (34.3 ppb, p = 0.002). Nasal NO levels were higher in rhinitis patients than other UAD categories, irrespective of the asthma concomitance. Nasal NO levels were higher in asthmatics with rhinitis (112.8 ppb) than those without UAD (67.2 ppb, p = 0.001) and those with CRS (57.6 ppb, p < 0.0001). A receiver-operating-characteristic curve analysis for detecting comorbid allergic rhinitis (AR) in asthmatics showed a high area under the curve (0.87). Nasal NO levels were positively correlated with FeNO₅₀ levels (ρ = 0.56, p = 0.003) in asthmatics with rhinitis. In contrast, they were negatively correlated with the Lund-Macay (ρ = -0.46, p = 0.03) and ACQ scores (ρ = -0.52, p = 0.009) in asthmatics with CRS.

CONCLUSIONS

Higher nasal NO levels reflect the presence of AR, irrespective of asthma concomitance. Higher FeNO₅₀ levels reflect the presence of CRS and asthma. These NO measurements are useful for assessing comorbid UAD in asthmatics.

Longitudinal analysis of inflammatory biomarkers during acute rhinosinusitis

Objective

To illuminate the pathophysiology of acute rhinosinusitis (ARS) with sequential monitoring of inflammatory biomarkers during an ARS episode and to clarify their diagnostic usability in bacterial ARS.

Study Design

Inception cohort study with 50 conscripts with ARS.

Methods

We collected peripheral blood high‐sensitive C‐reactive protein (hs‐CRP), white blood cell (WBC), procalcitonin, and nasal nitric oxide (nNO) counts at 2 to 3 and 9 to 10 days of symptoms during an ARS episode. We simultaneously gathered various clinical parameters and microbiological samples. Bacterial ARS was confirmed with a positive culture of sinus aspirate.

Results

Reciprocal correlations and a significant change in biomarker levels between the two visits suggest that ARS involves a local and systemic inflammatory response that was strongest at 2 to 3 days. High‐sensitive CRP and nNO reflected responses best (52% had increased CRP levels at 2–3 days; 66% had decreased nNO levels). White blood cell and procalcitonin counts rarely exceeded the reference range. Increased local and systemic inflammatory response were linked to multiple, adenoviral, or influenza A viral etiology or the detection of bacterial ARS. Local response correlated with imaging findings of wide paranasal sinus involvement and ostiomeatal complex occlusion. At 9 to 10 days, elevated (≥ 11 mg/L) and moderately elevated (≥ 49 mg/L) hs‐CRP predicted bacterial ARS well (likelihood ratio [LR]+ 3.3 and LR+ 15.8, respectively), but the sensitivity for both findings remained low.

Conclusion

Acute rhinosinusitis (particularly bacterial ARS) involves a local and systemic inflammatory response that is strongest at the beginning of symptoms. Elevated hs‐CRP supports the diagnosis of bacterial ARS.

Level of Evidence

4. Laryngoscope, 2016 127:E55–E61, 2017

Sinus opacification in the intensive care unit patient

OBJECTIVES/HYPOTHESIS

The significance of sinus opacification in intensive care unit (ICU) patients remains uncertain. Our objectives were to determine the baseline incidence and risk factors associated with the development of radiographic sinus abnormalities in the ICU population.

METHODS

A retrospective study of head computed tomography scan or magnetic resonance imaging from April 2013 through April 2014 of 612 neurologic ICU patients at the University of Pittsburgh Medical Center Presbyterian Hospital, Pittsburgh, Pennsylvania, was performed. Images were scored by the Lund-Mackay system (LMS). Exclusion criteria included prior sinus or skull base surgery, history of sinonasal malignancy, facial fractures, ICU admission less than 3 days, or inadequate imaging.

RESULTS

At the time of admission, 40.7% of patients had a LMS greater than zero (mean 2.2). Worsening sinus opacification occurred in 42.6% of patients (mean highest LMS 4.6) during ICU admission. There was a peak between days 8 and 10, during which 65% of scans exhibited worsening opacification compared to baseline. On multivariate analysis, risk factors associated with increased sinus opacification (higher LMS) included the presence of an endotracheal tube (odds ration [OR] 3.28, P < .001) or nasogastric tube (OR 3.34, P < .001) and increased length of stay (OR 2.50, P < .001). Age greater than 60 was found to be protective for the development of worsening sinus opacification (OR 0.57, P = .007).

CONCLUSION

Using serial imaging and comparison control groups, this study finds that there is a high baseline incidence of sinus opacification in the ICU population. Prolonged length of stay, younger age, and presence of nasogastric or endotracheal tubes all corresponded to worsening LMS.

LEVEL OF EVIDENCE

4. Laryngoscope, 126:2433-2438, 2016.

Chronic rhinosinusitis pathogenesis

There are a variety of medical conditions associated with chronic sinonasal inflammation, including chronic rhinosinusitis (CRS) and cystic fibrosis. In particular, CRS can be divided into 2 major subgroups based on whether nasal polyps are present or absent. Unfortunately, clinical treatment strategies for patients with chronic sinonasal inflammation are limited, in part because the underlying mechanisms contributing to disease pathology are heterogeneous and not entirely known. It is hypothesized that alterations in mucociliary clearance, abnormalities in the sinonasal epithelial cell barrier, and tissue remodeling all contribute to the chronic inflammatory and tissue-deforming processes characteristic of CRS. Additionally, the host innate and adaptive immune responses are also significantly activated and might be involved in pathogenesis. Recent advancements in the understanding of CRS pathogenesis are highlighted in this review, with special focus placed on the roles of epithelial cells and the host immune response in patients with cystic fibrosis, CRS without nasal polyps, or CRS with nasal polyps.

A role for airway taste receptor modulation in the treatment of upper respiratory infections

Taste receptors, initially identified in the oral epithelium, have since been shown to be widely distributed, being found in the upper and lower respiratory tracts, gastrointestinal epithelium, thyroid, and brain. The presence of taste receptors in the nasal epithelium has led to the discovery of their role in innate immunity, defending the paranasal sinuses against pathogens. This article addresses the current paradigm for understanding the role of extraoral taste receptors, specifically the T2R38 bitter taste receptor and the T1R2+3 sweet taste receptor, in respiratory innate defenses and presents evidence for the use of these and other taste receptors as therapeutic targets in the management of chronic rhinosinusitis. Future studies should focus on understanding the polymorphisms of taste receptors beyond T2R38 to fully elucidate their potential therapeutic use and lay the groundwork for their modulation in a clinical setting to decrease the health impact and economic burden of upper respiratory disease.

Primary ciliary dyskinesia in adults

INTRODUCTION

Primary ciliary dyskinesia is an autosomal recessive genetic disorder leading to structural and/or functional abnormalities of motor cilia. Impaired mucociliary clearance is responsible for the development of a multi-organ disease, which particularly affects the upper and lower airways.

STATE OF THE ART

In adults, primary ciliary dyskinesia is mainly characterized by bronchiectasis and chronic ear and sinus disorders. Situs inversus is found in half of patients and fertility disorders are commonly associated. Diagnosis is based on specialized tests: reduced level of nasal nitric oxide concentrations is suggestive of primary ciliary dyskinesia, but only a nasal or bronchial biopsy/brushing with analysis of beat pattern by videomicroscopy and/or analysis of cilia morphology by electronic microscopy can confirm the diagnosis. However, the diagnosis is difficult to achieve due to the limited access to these specialized tests and to difficulties in interpreting them. Genetic tests are under development and may provide new diagnostic tools. Treatment is symptomatic, based on airway clearance techniques (e.g., physiotherapy) and systemic and/or inhaled antibiotics. Prognosis is related to the severity of the respiratory impairment, which can be moderate or severe.

PERSPECTIVES AND CONCLUSIONS

Diagnosis and management of primary ciliary dyskinesia remain poorly defined and should be supported by specialized centers to standardize the diagnosis, improve the treatment and promote research.

Role of the bitter taste receptor T2R38 in upper respiratory infection and chronic rhinosinusitis

PURPOSE OF REVIEW

Taste receptor family 2 (T2R) bitter taste receptors were originally identified and named on the basis of their role in type 2 taste cells of the tongue, in which they serve to detect the presence of potentially harmful ingested chemicals. In 2009, researchers demonstrated that airway epithelial cells also express T2R receptors, but their role in airway physiology and human disease has only recently begun to be identified.

RECENT FINDINGS

Recent research has demonstrated that at least one airway T2R receptor, taste receptor family 2 isoform 38 protein (T2R38) is activated by secreted bacterial products. Activation of T2R38 in sinonasal epithelial cells stimulates nitric oxide production, increasing ciliary beating and directly killing bacteria. Clinical studies have also found correlations of TAS2R38 genotype with susceptibility to gram-negative upper respiratory infection and established T2R38 as an independent risk factor for chronic rhinosinusitis requiring sinus surgery.

SUMMARY

These recent studies identify a role for T2R38 in sinonasal innate immunity and chronic rhinosinusitis. Clinical implications include the potential development of T2R38-directed topical therapies, as well as using taste testing and/or genotyping to predict susceptibility to infection. Further studies are needed to more clearly determine how TAS2R38 genotype affects patient outcomes in chronic rhinosinusitis and other upper airway diseases.

Cyclic GMP and Cilia Motility

Motile cilia of the lungs respond to environmental challenges by increasing their ciliary beat frequency in order to enhance mucociliary clearance as a fundamental tenant of innate defense. One important second messenger in transducing the regulable nature of motile cilia is cyclic guanosine 3′,5′-monophosphate (cGMP). In this review, the history of cGMP action is presented and a survey of the existing data addressing cGMP action in ciliary motility is presented. Nitric oxide (NO)-mediated regulation of cGMP in ciliated cells is presented in the context of alcohol-induced cilia function and dysfunction.

Nasal nitric oxide as a marker of sinus mucosal health in patients with nasal polyposis

BACKGROUND

Reduced nasal nitric oxide (nNO) has been shown in patients with chronic rhinosinusitis (CRS) but its clinical significance remains uncertain. The objective of this study was to measure nNO changes in patients undergoing endoscopic sinus surgery (ESS) for CRS and to explore its relationship to clinical measures of sinus mucosal health postoperatively.

METHODS

This was a prospective study of CRS patients undergoing ESS. Patients had the following measurements at baseline and at 1 and 6 months post-ESS: nNO levels, Lund-Kennedy Endoscopy Score (LKES), and 22-item Sino-Nasal Outcome Test (SNOT-22) score. Statistical analysis was performed using GraphPad Prism 6.

RESULTS

Thirty-nine patients were enrolled, of these 84.6% had CRS with nasal polyps. Baseline Lund-Mackay computed tomography (CT) score was 16.9 ± 5.1. There was a statistically significant increase in nNO levels from baseline to 1 month and 6 months postoperatively (p < 0.0001). The SNOT-22 and LKES followed a similar trend with a significant and sustained improvement at 1 month and 6 months post-ESS (p < 0.0001). Subgroup analysis revealed that changes in nNO were driven by the polyp cohort because nonpolyp patients had no significant changes in their nNO postoperatively. No correlation was found between nNO levels and SNOT-22. However, a significant negative correlation was found between nNO and LKES (p < 0.0001), suggesting healthier sinus mucosa was associated with higher nNO levels.

CONCLUSION

This is the first study to show that nNO levels may be a marker of sinus mucosal health following ESS in patients with polyps. This has important implications for nNO in its potential etiologic role in mediating ongoing sinus inflammation.

Nitric Oxide Regulation of Bacterial Biofilms

Biofilms are surface-associated, multicellular communities of bacteria. Once established, they are extremely difficult to eradicate by antimicrobial treatment. It has been demonstrated in many species that biofilm formation may be regulated by the diatomic signaling molecule nitric oxide (NO). Although this is still a relatively new area of research, we review here the literature reporting an effect of NO on bacterial biofilm formation, emphasizing dose-dependent responses to NO concentrations when possible. Where it has been investigated, the underlying NO sensors or signaling pathways are also discussed. Most of the examples of NO-mediated biofilm regulation have been documented with exogenously applied NO, but we also survey possible natural sources of NO in biofilm regulation, including endogenously generated NO. Finally, because of the apparent broad-spectrum, antibiofilm effects of NO, NO-releasing materials and prodrugs have also been explored in this minireview.

Numerical simulation of airflow and micro-particle deposition in human nasal airway pre- and post-virtual sphenoidotomy surgery

In the present study, the effects of endoscopic sphenoidotomy surgery on the flow patterns and deposition of micro-particles in the human nasal airway and sphenoid sinus were investigated. A realistic model of a human nasal passage including nasal cavity and paranasal sinuses was constructed using a series of CT scan images of a healthy subject. Then, a virtual sphenoidotomy by endoscopic sinus surgery was performed in the left nasal passage and sphenoid sinus. Transient airflow patterns pre- and post-surgery during a full breathing cycle (inhalation and exhalation) were simulated numerically under cyclic flow condition. The Lagrangian approach was used for evaluating the transport and deposition of inhaled micro-particles. An unsteady particle tracking was performed for the inhalation phase of the breathing cycle for the case that particles were continuously entering into the nasal airway. The total deposition pattern and sphenoid deposition fraction of micro-particles were evaluated and compared for pre- and post-surgery cases. The presented results show that sphenoidotomy increased the airflow into the sphenoid sinus, which led to increased deposition of micro-particles in this region. Particles up to 25 μm were able to penetrate into the sphenoid in the post-operation case, and the highest deposition in the sphenoid for the resting breathing rate occurred for 10 μm particles at about 1.5%.

Arginine and citrulline and the immune response in sepsis

Arginine, a semi-essential amino acid is an important initiator of the immune response. Arginine serves as a precursor in several metabolic pathways in different organs. In the immune response, arginine metabolism and availability is determined by the nitric oxide synthases and the arginase enzymes, which convert arginine into nitric oxide (NO) and ornithine, respectively. Limitations in arginine availability during inflammatory conditions regulate macrophages and T-lymfocyte activation. Furthermore, over the past years more evidence has been gathered which showed that arginine and citrulline deficiencies may underlie the detrimental outcome of inflammatory conditions, such as sepsis and endotoxemia. Not only does the immune response contribute to the arginine deficiency, also the impaired arginine de novo synthesis in the kidney has a key role in the eventual observed arginine deficiency. The complex interplay between the immune response and the arginine-NO metabolism is further underscored by recent data of our group. In this review we give an overview of physiological arginine and citrulline metabolism and we address the experimental and clinical studies in which the arginine-citrulline NO pathway plays an essential role in the immune response, as initiator and therapeutic target.

[The paranasal sinuses as the nitric oxide depot]

This paper was designed to report the currently available data on physiology of the nasal cavity and paranasal sinuses together with the results of national and international investigations on the computer modeling of the air flow in these structures. Also discussed are the gas composition in the paranasal sinuses and the potential factors responsible for the changes in the concentration of nitric oxide with the chemical formula of NO in the nasal cavity and paranasal sinuses.

Taste receptors in innate immunity

Taste receptors were first identified on the tongue, where they initiate a signaling pathway that communicates information to the brain about the nutrient content or potential toxicity of ingested foods. However, recent research has shown that taste receptors are also expressed in a myriad of other tissues, from the airway and gastrointestinal epithelia to the pancreas and brain. The functions of many of these extraoral taste receptors remain unknown, but emerging evidence suggests that bitter and sweet taste receptors in the airway are important sentinels of innate immunity. This review discusses taste receptor signaling, focusing on the G-protein-coupled receptors that detect bitter, sweet, and savory tastes, followed by an overview of extraoral taste receptors and in-depth discussion of studies demonstrating the roles of taste receptors in airway innate immunity. Future research on extraoral taste receptors has significant potential for identification of novel immune mechanisms and insights into host-pathogen interactions.

Liposome-encapsulated ISMN: a novel nitric oxide-based therapeutic agent against Staphylococcus aureus biofilms

Background

Staphylococcus aureus in its biofilm form has been associated with recalcitrant chronic rhinosinusitis with significant resistance to conventional therapies. This study aims to determine if liposomal-encapsulation of a precursor of the naturally occurring antimicrobial nitric oxide (NO) enhances its desired anti-biofilm effects against S. aureus, in the hope that improving its efficacy can provide an effective topical agent for future clinical use.

Methodology

S. aureus ATCC 25923 biofilms were grown in-vitro using the Minimum Biofilm Eradication Concentration (MBEC) device and exposed to 3 and 60 mg/mL of the NO donor isosorbide mononitrate (ISMN) encapsulated into different anionic liposomal formulations based on particle size (unilamellar ULV, multilamellar MLV) and lipid content (5 and 25 mM) at 24 h and 5 min exposure times. Biofilms were viewed using Live-Dead Baclight stain and confocal scanning laser microscopy and quantified using the software COMSTAT2.

Results

At 3 and 60 mg/mL, ISMN-ULV liposomes had comparable and significant anti-biofilm effects compared to untreated control at 24 h exposure (p = 0.012 and 0.02 respectively). ULV blanks also had significant anti-biofilm effects at both 24 h and 5 min exposure (p = 0.02 and 0.047 respectively). At 5 min exposure, 60 mg/mL ISMN-MLV liposomes appeared to have greater anti-biofilm effects compared to pure ISMN or ULV particles. Increasing liposomal lipid content improved the anti-biofilm efficacy of both MLV and ULVs at 5 min exposure.

Conclusion

Liposome-encapsulated “nitric oxide” is highly effective in eradicating S. aureus biofilms in-vitro, giving great promise for use in the clinical setting to treat this burdensome infection. Further studies however are needed to assess its safety and efficacy in-vivo before clinical translation is attempted.

Correlation of nasal nitric oxide measurement with computed tomography findings in chronic rhinosinusitis

Nitric oxide (NO) is a biological messenger produced by mammalian cells serving various functions including regulation of blood flow, platelet function, immunity, and neurotransmission. The paranasal sinuses and nasal mucosa are a major source of exhaled NO. The aim of the study is to compare the nasal NO (nNO) levels in patients with chronic rhinosinusitis with those of common cold patients and controls and to correlate CT scores with nNO levels. The nasal concentration of NO was measured by electroluminescence in 13 healthy volunteers, in 13 patients suffering from common cold and 13 patients with chronic rhinosinusitis. The concentration of NO was correlated with symptom scores, endoscopic findings and CT findings. The measured levels of NO did not differ between healthy volunteers and common cold patients, but they were significantly lower in patients suffering from chronic rhinosinusitis. As NO is a regulator of mucociliary activity and has bacteriostatic and antiviral effects, the decreased concentration of nNO in patients suffering from sinusitis suggests that lack of NO may contribute to the pathogenesis of this disease. Thus, nNO, which is easily measured, provides a valuable non-invasive objective measure of chronic rhinosinusitis.

Nasal and Exhaled Nitric Oxide in Chronic Rhinosinusitis with Polyps

Background

The ciliary epithelial cells in the paranasal sinuses produce nasal nitric oxide (NO) continuously and plays a variety of roles in the paranasal sinuses. The purpose of this study was to assess whether we can use the levels of nasal NO (nNO) and exhaled NO (eNO) as a tool for evaluation in chronic rhinosinusitis (CRS) with nasal polyp patients.

Methods

We used chemiluminescent NO analyzer to measure nNO and eNO among normal controls (32) and CRS with polyp (30) and CRS with polyp and allergic rhinitis patients (27) and compared it with various clinical symptoms, laboratory data, and computed tomography (CT) scores.

Results

Levels of nNO were significantly lower in patients with CRS with polyps (88.5 ± 54.7 ppb) compared with controls (241.0 ± 89.5 ppb). Levels of nNO in CRS with polyps and allergic rhinitis (167.0 ± 47.6 ppb) were significantly higher than CRS with polyps and lower than controls. A significant inverse relationship was observed between nNO and sinus CT scores, severity of nasal obstruction, and purulent rhinorrhea in CRS with polyps. Low values of nNO separated well patients with CRS with polyps, and the cutoff value of <163 ppb was associated with the best com nation of specificity (93%) and sensitivity (81%). A significant positive relationship was observed between eNO and CT scores.

Conclusion

The nNO could be used for another screening of CRS with polyps for the more severe phenotypes, which may eventually have to be treated with surgery.

The effect of a middle meatal antrostomy on nitric oxide ventilation in the maxillary sinus

The effects of middle meatal antrostomy (MMA) on air and nitric oxide exchange in the human maxillary sinus were quantified using the computational fluid dynamics technique. One full period of respiration was considered in the anatomically correct numerical domain. The simulation results showed that MMA did not cause any noticeable change in the velocity or pressure fields at a global level but induced local velocity as high as 0.21m/s inside the maxillary. Therefore, enlargement of the ostium area by MMA allows inspiratory and expiratory nasal airflow to induce significant convective flows in the sinus, which in turn enhances gas exchange dramatically. At the end of the inspiration phase, NO concentration in the maxillary sinus decreased to about 54% of the initial value. NO concentration decreased only by about 30% during the expiration phase. This difference in reduction rate is thought to result from the difference in airflow velocity in the extended ostium during inspiration vs. expiration.

Mouse nasal epithelial innate immune responses to Pseudomonas aeruginosa quorum-sensing molecules require taste signaling components

We previously observed that the human bitter taste receptor T2R38 is an important component of upper respiratory innate defense because it detects acyl homoserine lactone (AHL) quorum-sensing molecules secreted by Gram-negative bacteria. T2R38 activation in human sinonasal epithelial cells stimulates calcium and NO signals that increase mucociliary clearance, the major physical respiratory defense against inhaled pathogens. While mice do not have a clear T2R38 ortholog, they do have bitter taste receptors capable of responding to T2R38 agonists, suggesting that T2R-mediated innate immune mechanisms may be conserved in mice. We examined whether AHLs activate calcium and NO signaling in mouse nasal epithelial cells, and utilized pharmacology, as well as cells from knockout mice lacking important components of canonical taste signal transduction pathways, to determine if AHL-stimulated responses require taste signaling molecules. We found that AHLs stimulate calcium-dependent NO production that increases mucociliary clearance and thus likely serves an innate immune role against Gram-negative bacteria. These responses require PLCβ2 and TRPM5 taste signaling components, but not α-gustducin. These data suggest the mouse may be a useful model for further studies of T2R-mediated innate immunity.

Paranasal sinus nitric oxide and migraine: a new hypothesis on the sino rhinogenic theory

Migraine is a debilitating illness that has no exact bio molecule to explain its pathology. After reviewing the neurophysiological and biochemical basis of the research findings of nitric oxide and migraine, I present to the best of my knowledge the first para sinus nitric oxide mediated neurobiophysiological hypothesis for migraine of sino rhinogenic origin. The diffused paranasal sinus nitric oxide in the nasal mucosa could be the primary molecule that initiates migraine and is termed Sinus Hypoxic Nitric Oxide Theory. This hypothesis regards repetitive or intermittent activation of the trigeminal sensory nerve and blood vessels in the nasal mucosa. Production of paranasal sinus nitric oxide is mainly induced by hypoxia due to several independent factors and the diffusion of paranasal sinus nitric oxide depends on the vulnerable surface area in the nasal cavity. Apart from the known trigeminal nociceptive impulse in the migraine, two main peripheral trigeminal nerve activating mechanisms may induce migraine. First the nerve endings of the nasal mucosa which are directly stimulated by diffused paranasal sinus nitric oxide are indirectly stimulated by vasoactive substances released by antidromic activation of the nerve, parasympathetic efferent of the nerve and sterile neurogenic inflammation. Secondly, the perivascular nerve of nasal mucosal and the meningial blood vessels are directly stimulated by either diffused paranasal sinus nitric oxide or by shear stress mediation. The nerve impulses of the trigeminal sensory nerve, projected at trigeminal nucleus caudalis to the central nerve system and low plasma magnesium due to the consequence of shear stress gives rise to the symptoms of migraine. Moreover sino rhinogenic impulses may mediate to disruption of inhibitory sensitization modulated of sensory input and cause sensory hiperexcitability. In addition neuronal stimulation proposed by some migraine hypotheses could also give rise to migraine headache when the sino rhinogenic vulnerable factors induce the migraine pathophysiology. Indeed this article explains a new pathophysiological initiation between sino rhinogenic nitric oxide effects and migraine and provides an initial step for the obscured or neglected etiologically important neuro vascular impulse generating pathway. The patients who are clinically suspected of having headaches should receive comprehensive sino rhinological examination and evaluation based on the sinus hypoxic nitric oxide theory. A standard surgical and medical management of migraine that links with the sinus hypoxic nitric oxide theory may restore the hypoxic state or reduce or remove the paranasal sinus nitric oxide diffusing surface. It warrants clinical testing.

Effect of accessory ostia on maxillary sinus ventilation: a computational fluid dynamics (CFD) study

We evaluated, by CFD simulation, effects of accessory ostium (AO) on maxillary sinus ventilation. A three-dimensional nasal model was constructed from an adult CT scan with two left maxillary AOs (sinus I) and one right AO (sinus II), then compared to an identical control model with all AOs sealed (sinuses III and IV). Transient simulations of quiet inspiration and expiration at 15 L/min, and nasal blow at 48 L/min, were calculated for both models using low-Reynolds-number turbulent analysis. At low flows, ventilation rates in sinuses with AOs (I ≈ 0.46 L/min, II ≈ 0.54 L/min), were both more than a magnitude higher than sinuses without AOs (II I ≈ 0.019 L/min, IV ≈ 0.020 L/min). Absence of AO almost completely prevented sinus ventilation. Increased ventilation of sinuses with AOs is complex. Under high flow conditions mimicking nose blowing, in sinuses II, III, and IV, the sinus flow rate increased. In contrast, the airflow direction through sinus I reversed between inspiration and expiration, while it remained almost constant throughout the respiration cycle in sinus II. CFD simulation demonstrated that AOs markedly increase maxillary sinus airflow rates and alter sinus air circulation patterns. Whether these airflow changes impact maxillary sinus physiology or pathophysiology is unknown.

The quantitative effect of an accessory ostium on ventilation of the maxillary sinus

The airflow and gas exchange behaviors of the human maxillary sinus were quantified to better understand the effect of an accessory ostium (AO). An anatomically correct numerical domain was constructed using CT data from a male patient with mild nasal obstruction. For the purpose of comparison, a numerical model without an AO was also generated by artificially removing the AO from the original model using CAD software. A steady-flow field through the nasal cavity was simulated using ANSYS-FLUENT v13.0 with a target flow rate of 250 ml/s. The Volume of Fluid (VOF) method was used to investigate the concentration field of nitric oxide (NO) initially filled in the maxillary sinus. The simulation results showed that a transit flow through the maxillary sinus developed in the presence of an AO. As the flow entered the sinus through either a natural or accessory ostium from the middle meatus, the velocity was significantly reduced to a local maximum of approximately 0.034 m/s inside the sinus. This by-pass flow rate through the sinus of 2.186×10(-1) to 3.591×10(-1) ml/s was a small fraction of the total flow rate inhaled from the nostril, but it effectively changed the local flow topology and led to a larger reduction in NO concentration in the maxillary sinus. This more rapid reduction in NO concentration was due to enhanced ventilation activity afforded by convective transport of the transit stream through the flow path connecting the natural ostium and the AO. The inspiration and expiration phases were qualitatively similar in flow pattern except for the flow direction in the maxillary sinus, suggesting that the AO plays a similar physiological role during both inspiration and expiration in terms of ventilation.

Expression of nitric oxide synthases in leukocytes in nasal polyps

BACKGROUND

Nitric oxide (NO) has various roles in airway physiology and pathophysiology. Monitoring exhaled NO levels is increasingly common to measure airways inflammation and inhaled NO studied for its therapeutic value in premature infants and adult respiratory distress syndrome. NO is produced by 3 isoforms of NO synthase (NOS1, 2, 3), and each can play distinct and perhaps overlapping roles in the airways. However, the distribution, regulation, and functions of NOS in various cells in the upper airways, particularly in leukocytes, are incompletely understood.

OBJECTIVE

To characterize the expression of NOS isoforms in leukocytes in normal middle turbinate tissues (MT) and in inflammatory nasal tissue (nasal polyps, NP).

METHODS

Normal MT tissue was collected from surgical specimens that were to be discarded. The NP samples were from surgical tissue archives of 15 patients with chronic rhinosinusitis. Isoforms of NOS in cells were identified by double immunostaining using NOS isoform-specific and leukocyte-specific (mast cell, eosinophil, macrophage, neutrophil, or T cell) antibodies.

RESULTS

The proportion of total cells below the epithelium that were positive for each isoform of NOS was higher in NP than in MT. Each isoform of NOS was found in all leukocyte populations studied, and there were significant differences in the percentage of leukocytes expressing NOS isoforms between MT and NP.

CONCLUSION

All isoforms of NOS are expressed in leukocytes in MT and NP, and their expression varies among leukocyte types. Our data provide a basis to investigate the regulation, cell distribution, and distinct functions of NOS isoforms in normal and inflamed nasal tissues.

The effects of nitric oxide on Staphylococcus aureus biofilm growth and its implications in chronic rhinosinusitis

BACKGROUND

The relationship between sinonasal nitric oxide (NO) levels and the pathogenic organism Staphylococcus aureus is yet to be established. High NO levels measured in healthy sinuses likely contribute to maintenance of relative sterility. Lower concentrations such as is found in the sinuses of chronic rhinosinusitis (CRS) patients may decrease this effect. S. aureus in biofilm form has recently been implicated in recalcitrant CRS, its isolation predicting a higher risk of posttreatment reinfection. This in vitro study aims to characterize the changes in S. aureus biofilm formation when exposed to different NO levels mimicking the normal and diseased NO sinus concentrations reported in previous literature in an in vitro setting.

METHODS

S. aureus ATCC 25923 and 7 clinical isolates were cultured in biofilm form using the MBEC device and the established biofilms exposed to 1 to 1000 μM NO concentrations. Biofilms were visualized using Live/Dead Baclight stain and confocal scanning laser microscopy, and quantified using Comstat2, a biofilm quantification software.

RESULTS

Biofilm biomass decreases from an average of 0.105 to 0.057 μm(3) /μm(2) at higher NO concentrations (125-1000 μM), but is increased to 0.470 μm(3) /μm(2) at lower NO concentrations (0.9-2.0 μM). The average biomass at high vs low concentrations are statistically significant (p < 0.001).

CONCLUSION

S. aureus biofilm formation varies across exposure to different NO levels, with antibiofilm effects at higher concentrations, and enhanced biofilm formation at lower or subphysiologic concentrations. These results coincide with the often dualistic function of NO, and have implications in its future use in the treatment of CRS.

Expression of nitric oxide synthases in primary ciliary dyskinesia

Nitric oxide is believed to play a central role in nonspecific defense of upper airways. Patients with primary ciliary dyskinesia have very low concentration of nasal nitric oxide, which may contribute to the chronic upper airway diseases encountered by these patients. The mechanisms underlying this drop of nasal nitric oxide in primary ciliary dyskinesia are still unknown. The goal of the present work was to study nitric oxide synthases expression in upper airway tissues from patients with primary ciliary dyskinesia. For this purpose, 5 patients with primary ciliary dyskinesia and 10 nonallergic age-matched patients without primary ciliary dyskinesia undergoing nasal polypectomy were included. Nasal nitric oxide concentration was measured before polypectomy, and nitric oxide synthase expression and function were studied in nasal polyps. The nasal nitric oxide in patients with primary ciliary dyskinesia was lower than that in patients without primary ciliary dyskinesia (13 [9-16] ppb versus 210 [167-254] ppb, P < .0001). Nitric oxide synthase 2 immunostaining was prominent at the apical part of the ciliated epithelial cells and was similar in both groups. Nitric oxide synthase 3 staining was restricted to endothelial cells in both groups. In addition, reduced nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase activity was superimposable to nitric oxide synthases 2 and 3 immunostaining, suggesting a preserved NADPH-activity of nitric oxide synthase. We therefore conclude that the drop in nasal nitric oxide in patients with primary ciliary dyskinesia is not secondary to the loss of nitric oxide synthase expression.

Prediction of nosocomial infection acquisition in ventilated patients by nasal nitric oxide: proof-of-concept study

The development of biomarkers able to predict the occurrence of nosocomial infection could help manage preventive strategies, especially in medical patients whose degree of acquired immunosuppression may be variable. We hypothesized that the NO fraction present in the airways (upper and lower) of critically ill patients under mechanical ventilation could constitute such a biomarker. We conducted an observational proof-of-concept study in a medical intensive care unit of a teaching hospital. Forty-five patients (26 men; 72 [25th-75th percentiles] years [56-82]; Simplified Acute Physiology Score II, 63 [50-81], 14 infected) under mechanical ventilation (>3 days) underwent on day 1 and day 3 of their stay: nasal and exhaled (partitioned in bronchial and alveolar sources) bedside NO measurements, determination of urine NO end products and plasma cytokine (IL-6, IL-10) concentrations, and Sequential Organ Failure Assessment score calculation. Nosocomial infection incidence was recorded during the 15 subsequent days. Fifteen patients (33%) acquired a nosocomial infection (16 infections, 15 ventilator-associated pneumonia and 1 bacteremia). Nasal NO was the only marker significantly different between patients with and without subsequent infection (day 1, 52 ppb [20-142] vs. 134 [84-203], P = 0.038; day 3, 98 ppb [22-140] vs. 225 [89-288], P = 0.006, respectively). Nasal NO fraction 148 ppb or less at day 3 had an 80% sensitivity, a 70% specificity, and an odds ratio of 2.7 (95% confidence interval, 1.9-3.8) to predict acquisition of nosocomial infection. Nonsurvivors had a higher IL-6 concentration on day 3 (P = 0.014), whereas their nasal NO fractions were not significantly different. Nasal NO seems to be a relatively sensitive and specific biomarker of subsequent nosocomial infection acquisition (at least for ventilator-associated pneumonia), which warrants confirmation in a multicenter trial.

Maxillary sinusitis in patients ventilated for a severe head injury and with nostrils free of any foreign body

BACKGROUND

This study aims to determine the frequency of maxillary sinusitis in the patients with traumatic head injury and nostrils free of any foreign body. In addition, the sensitivity and specificity of ultrasonography (US) for the detection of the presence of fluid in maxillary sinuses were evaluated.

PATIENTS AND METHODS

Forty patients with severe traumatic head injury were included in the study. The patients who had displaced maxillary sinus fracture at the medial wall and naso-tracheal and/or naso-gastric tube were excluded. Paranasal computed tomography (CT) was performed along with the routine cranial CT scanning or in case of unknown source of infection and compared with the results of ultrasonographic examination of maxillary sinuses performed by a single radiologist who was unaware of the CT results. In the patients, who had clinical and radiological signs of sinusitis, a trans-nasal puncture was performed using sinoject (SinoJect, ATOS Medical, Sweden), a spring-activated puncture instrument, to take a sample for microbiologic examination and to drain maxillary sinuses.

RESULTS

Eighty-five percent of the patients were tracheotomised on the fifth day (on average) of their intensive care unit (ICU) stay. The frequency of sinusitis in the study group was found to be 32.5% (13 patients). The most frequently isolated species were Pseudomonas spp. (37.5%), Escherichia coli (20.8%) and Peptostreptococcus (16.7%). Five of the aspirates were polymicrobial. The sensitivity, specificity, positive predictive value and negative predictive value of B-mode US, compared with CT for the detection of fluid presence in maxillary sinuses in a 100 maxillary sinus examinations, were 92.2%, 81.6%, 83.9% and 90.9%, respectively.

CONCLUSION

Maxillary sinusitis should be considered as a source of infection or sepsis in patients with traumatic head injury because of its high frequency. US is likely to be used as the first-line diagnostic tool for the determination of fluid in maxillary sinuses, especially in patients who do not require CT or cannot be transported to a radiology unit for CT.

Effects of nitric oxide in mucociliary transport

The airways are made up of ciliated epithelium which secretes mucous, protecting the respiratory tract from particles inhaled during breathing. Its is paramount to understand the physiology and the mechanisms involved in mucociliary activity. Literature suggests that Nitric oxide (NO), especially the one produced by iNOS expression, maintains the mucociliary function and the immune defense of the nasal cavity.

Aim

to assess NO participation and the enzymatic pathways in the production of NO and mucociliary transport, using constructive and inductive NO synthetase inhibitors, L-NAME and aminoguanidine, respectively.

Materials and methods

frog palates were prepared and immerse in ringer (control), L-NAME or aminoguanidine solutions. The palates were immerse in these solutions for four periods of 15 minutes. Mucociliary transport measures were carried out before and after each exposure.

Results

control palates maintained stable their transportation speed. L-NAME increased, while aminoguanidine reduced mucous transportation velocity.

Conclusion

unspecific cNOS block with L-NAME and relatively specific iNOS block with aminoguanidine results leads us to propose that depending on the pathway, the NO can increase or reduce mucociliary transport in frog palates.

Breathing pattern, CO2 elimination and the absence of exhaled NO in freely diving Weddell seals

Weddell seals undergo lung collapse during dives below 50 m depth. In order to explore the physiological mechanisms contributing to restoring lung volume and gas exchange after surfacing, we studied ventilatory parameters in three Weddell seals between dives from an isolated ice hole on McMurdo Sound, Antarctica.

METHODS

Lung volumes and CO(2) elimination were investigated using a pneumotachograph, infrared gas analysis, and nitrogen washout. Thoracic circumference was determined with a strain gauge. Exhaled nitric oxide was measured using chemiluminescence.

RESULTS

Breathing of Weddell seals was characterized by an apneustic pattern with end-inspiratory pauses with functional residual capacity at the end of inspiration. Respiratory flow rate and tidal volume peaked within the first 3 min after surfacing. Lung volume reductions before and increases after diving were approximately 20% of the lung volume at rest. Thoracic circumference changed by less than 2% during diving. The excess CO(2) eliminated after dives correlated closely with the duration of the preceding dive. Nitric oxide was not present in the expired gas.

CONCLUSION

Our data suggest that most of the changes in lung volume during diving result from compression and decompression of the gas remaining in the respiratory tract. Cranial shifts of the diaphragm and translocation of blood into the thorax rather than a reduction of thoracic circumference appear to compensate for lung collapse. The time to normalise gas exchange after surfacing was mainly determined by the accumulation of CO(2) during the dive. These findings underline the remarkable adaptations of the Weddell seal for restoring lung volume and gas exchange after diving.