Multiple roles of nitric oxide in the airways

Nitric oxide is endogenously released in the airways by nitric oxide synthase. Functionally, two isoforms of this enzyme exist: constitutive and inducible. The former seems to protect airways from excessive bronchoconstriction while the latter has a modulatory role in inflammatory disorders of the airways such as asthma. This review explores the physiological and pathophysiological role of endogenous nitric oxide in the airways, and the clinical aspects of monitoring nitric oxide in exhaled air of patients with respiratory disease.

Cellular and molecular mechanisms in chronic obstructive pulmonary disease: an overview

In the last decade, the analysis of bronchial biopsies and lung parenchyma obtained from chronic obstructive pulmonary disease (COPD) patients compared with those from smokers with normal lung function and non-smokers has provided new insights on the role of the different inflammatory and structural cells, their signalling pathways and mediators, contributing to a better knowledge of the pathogenesis of COPD. This review summarizes and discusses the lung pathology of COPD patients with emphasis on inflammatory cell phenotypes that predominate in different clinical conditions. In bronchial biopsies, a cascade of events takes place during progression from mild-to-severe disease. T lymphocytes, particularly CD8+ cells and macrophages are the prevalent inflammatory cells in the lung of healthy smokers and patients with mild COPD, while total and activated neutrophils predominate in severe COPD. The number of CD4+, CD8+ cells and macrophages expressing nuclear factor-kappa B (NF-kappaB), STAT-4 and IFN-gamma proteins as well as endothelial adhesion molecule-1 in endothelium is increased in mild/moderate disease. In contrast, activated neutrophils (MPO+ cells) and increased nitrotyrosine immunoreactivity develops in severe COPD. In bronchial biopsies obtained during COPD exacerbations, some studies have shown an increased T cell and granulocyte infiltration. Regular treatment with high doses of inhaled glucocorticoids does not significantly change the number of inflammatory cells in bronchial biopsies from patients with moderate COPD. The profile in lung parenchyma is similar to bronchial biopsies. 'Healthy' smokers and mild/moderate diseased patients show increased T lymphocyte infiltration in the peripheral airways. Pulmonary emphysema is associated with a general increase of inflammatory cells in the alveolar septa. The molecular mechanisms driving the lymphocyte and neutrophilic prevalence in mild and severe disease, respectively, needs to be extensively studied. Up-regulation of pro-inflammatory transcription factors NF-kappaB and STAT-4 in mild, activated epithelial and endothelial cells in the more severe disease may contribute to this differential prevalence of infiltrating cells.

High serum levels of tumour necrosis factor-alpha and interleukin-8 in severe asthma: markers of systemic inflammation?

BACKGROUND

Severe asthma is characterized by elevated levels of pro-inflammatory cytokines and neutrophilic inflammation in the airways. Blood cytokines, markers of 'systemic' inflammation, may be a feature of amplified inflammation in severe asthma.

OBJECTIVE

To detect differences in IL-8, TNF-alpha, IL-16 and IL-13 levels in the serum(s) of stable severe and mild-moderate asthmatics related to blood leucocytes proportion, airway calibre and exhaled nitric oxide (NO) levels.

METHODS

We assessed cytokine serum levels by ELISA and blood leucocyte counts by an alkaline peroxidase method in 20 healthy controls, 22 mild-moderate [forced expiratory volume in 1 s (FEV1)(%pred): 89+/-3] and 14 severe asthmatics [FEV1(%pred): 49+/-2].

RESULTS

IL-8 and TNF-alpha levels were higher in severe asthmatics than in mild-moderate asthmatics or in controls (P<0.05). No differences in IL-16 and IL-13 levels were detected. Severe asthmatics showed higher circulating neutrophil and eosinophil number than controls (P<0.05). In severe asthmatics, exhaled NO levels were superior than in controls (P<0.05), but inferior than in mild-moderate asthmatics (P<0.05). We found positive correlation between TNF-alpha levels and exhaled NO (r=0.67; P=0.01) or circulating neutrophil counts (r=0.57; P=0.03) in severe asthmatics.

CONCLUSION

sTNF-alpha and sIL-8 are markers of 'systemic' inflammation in severe asthmatics, in conjunction with augmented circulating neutrophils, suggesting the involvement of neutrophil-derived cytokine pattern in severe asthma.

Serum interleukin-17 levels are related to clinical severity in allergic rhinitis

BACKGROUND

T helper (Th)-17 cells are a subset of T helper lymphocytes that exert regulatory activities. Recently, it has been reported that serum interleukin (IL)-17 levels are high in the most severe cases of birch allergy studied outside the pollen season.

OBJECTIVE

The aim of this study was to investigate a possible relationship between serum IL-17 levels and clinical parameters in patients with allergic rhinitis studied during the pollen season.

METHODS

In all, 56 patients with persistent pollen-induced allergic rhinitis were evaluated during the pollen season. Serum IL-17 levels were evaluated by enzyme-linked immunosorbent assay. Symptoms were assessed by visual analogue scale, drug use was monitored and peripheral eosinophils were counted.

RESULTS

Serum IL-17 levels were significantly related to clinical symptoms, drug use and peripheral eosinophil counts (P = 0.0001 for all).

CONCLUSION

This study provides evidence that serum IL-17 level assessment might be considered to classify allergy severity.

Association of increased CCL5 and CXCL7 chemokine expression with neutrophil activation in severe stable COPD

BACKGROUND

Increased numbers of activated neutrophils have been reported in the bronchial mucosa of patients with stable chronic obstructive pulmonary disease (COPD), particularly in severe disease.

OBJECTIVES

To investigate the expression of neutrophilic chemokines and adhesion molecules in bronchial biopsies from patients with stable COPD of different severity (GOLD stages I-IV) compared with age-matched control subjects, smokers with normal lung function and never smokers.

METHODS

The expression of CCL5, CXCL1, 5, 6, 7 and 8, CXCR1, CXCR2, CD11b and CD44 was measured in the bronchial mucosa using immunohistochemistry, confocal immunofluorescence, real-time quantitative polymerase chain reaction (RT-QPCR) and Western blotting (WB).

RESULTS

The numbers of CCL5+ epithelial cells and CCL5+ and CXCL7+ immunostained cells were increased in the bronchial submucosa of patients with stable severe COPD compared with control never smokers and smokers with normal lung function. This was also confirmed at the level of mRNA expression. The numbers of CCL5+ cells in the submucosa of patients with COPD were 2-15 times higher than any other chemokines. There was no correlation between the number of these cells and the number of neutrophils in the bronchial submucosa. Compared with control smokers, the percentage of neutrophils co-expressing CD11b and CD44 receptors was significantly increased in the submucosa of patients with COPD.

CONCLUSION

The increased expression of CCL5 and CXCL7 in the bronchial mucosa of patients with stable COPD, together with an increased expression of extracellular matrix-binding receptors on neutrophils, may be involved in the pathogenesis of COPD.

Neutrophilic inflammation and IL-8 levels in induced sputum of alpha-1-antitrypsin PiMZ subjects

BACKGROUND

Severe alpha-1-antitrypsin deficiency (AATD), due to homozygosity for the protease inhibitor (Pi) Z allele, is a genetic risk factor for chronic obstructive pulmonary disease (COPD). In a previous study the sputum of severe AATD subjects with airflow obstruction showed a pattern of cellular inflammation similar to COPD patients. It is uncertain whether heterozygotes for the Z allele or intermediate deficiency (PiMZ) have an increased risk of developing COPD.

METHODS

Sputum cell counts and the supernatant level of the neutrophil chemoattractant interleukin (IL)-8 were investigated by sputum induction in 10 non-smoker asymptomatic PiMZ subjects with normal pulmonary function, 10 patients with stable COPD, and 10 age matched normal subjects. Data are expressed as mean (SD).

RESULTS

The mean (SD) number of neutrophils was significantly higher (p<0.01) in the sputum of PiMZ subjects (84.5 (22.2) x10(4)/ml) and patients with COPD (126.9 (18.8) x10(4)/ml) than in matched normal subjects (55.0 (8.7) x10(4)/ml). IL-8 levels were increased in PiMZ subjects (828.5 (490.6) ng/ml; median 1003.0 ng/ml; range 1260-100 ng/ml) and in COPD patients (882.5 (524.3) ng/ml; median 934.9 ng/ml; range 1506-258 mg/ml) compared with normal subjects (3.5 (0.5) ng/ml; median 3.5 ng/ml; range 4.5-2.5 ng/ml). There was a significant positive correlation between IL-8 supernatant concentration and neutrophil count in PiMZ subjects (p = 0.036; r = 0.66). An inverse correlation was observed between the percentage of neutrophils and forced expiratory volume in 1 second (% predicted) in patients with COPD (p = 0.04; r = -0.43).

CONCLUSIONS

These findings indicate that PiMZ subjects without airflow obstruction may have an IL-8 related neutrophilic inflammation in the airways, similar to stable COPD patients, suggesting an increased risk of developing pulmonary changes.

Nasal IL-17F is related to bronchial IL-17F/neutrophilia and exacerbations in stable atopic severe asthma

Severe asthma (SA) is associated with neutrophil recruitment and T helper (TH )17 chemokine overexpression in bronchial biopsies. We aimed to evaluate IL-17A and IL-17F expression in nasal/bronchial lamina propria of atopic mild-to-severe asthmatics and controls in relation to neutrophilia and asthma exacerbations. Cryostat sections of nasal/bronchial biopsies obtained from 14 SA and 14 mild asthma (MA) stable atopic patients with rhinitis, and seven healthy controls were analyzed by immunohistochemistry for neutrophils, IL-17A and IL-17F expression. Atopic SA showed an increase in asthma exacerbations number, IL-17F and IL-17A expression in nasal/bronchial lamina propria compared to MA and controls, and a higher expression of bronchial neutrophils in SA compared to MA and controls. In all asthmatics, significant relationships were found between bronchial IL-17F and neutrophils/FEV1 , nasal IL-17F and bronchial neutrophil/IL-17 markers and between the latter and exacerbations, suggesting that nasal IL-17F might be informative on bronchial IL17-driven neutrophilia in atopic SA.

Characterization of T2-Low and T2-High Asthma Phenotypes in Real-Life

Asthma is a heterogeneous and complex condition characterized by chronic airway inflammation, which may be clinically stratified into three main phenotypes: type 2 (T2) low, T2-high allergic, and T2-high non-allergic asthma. This real-world study investigated whether phenotyping patients with asthma using non-invasive parameters could be feasible to characterize the T2-low and T2-high asthma phenotypes in clinical practice. This cross-sectional observational study involved asthmatic outpatients (n = 503) referring to the Severe Asthma Centre of the San Luigi Gonzaga University Hospital. Participants were stratified according to the patterns of T2 inflammation and atopic sensitization. Among outpatients, 98 (19.5%) patients had T2-low asthma, 127 (25.2%) T2-high non-allergic, and 278 (55.3%) had T2-high allergic phenotype. In comparison to T2-low, allergic patients were younger (OR 0.945, p < 0.001) and thinner (OR 0.913, p < 0.001), had lower smoke exposure (OR 0.975, p < 0.001) and RV/TLC% (OR 0.950, p < 0.001), higher prevalence of asthma severity grade 5 (OR 2.236, p < 0.05), more frequent rhinitis (OR 3.491, p < 0.001) and chronic rhinosinusitis with (OR 2.650, p < 0.001) or without (OR 1.919, p < 0.05) nasal polyps, but less common arterial hypertension (OR 0.331, p < 0.001). T2-high non-allergic patients had intermediate characteristics. Non-invasive phenotyping of asthmatic patients is possible in clinical practice. Identifying characteristics in the three main asthma phenotypes could pave the way for further investigations on useful biomarkers for precision medicine.

miR-142-3p is associated with aberrant WNT signaling during airway remodeling in asthma

Asthma is characterized by a chronic inflammation and remodeling of the airways. Although inflammation can be controlled, therapeutic options to revert remodeling do not exist. Thus, there is a large and unmet need to understand the underlying molecular mechanisms to develop novel therapies. We previously identified a pivotal role for miR-142-3p in regulating airway smooth muscle (ASM) precursor cell proliferation during lung development by fine-tuning the Wingless/Integrase I (WNT) signaling. Thus, we here aimed to investigate the relevance of this interaction in asthma. We performed quantitative RT-PCR and immune staining in a murine model for ovalbumin-induced allergic airway inflammation and in bronchial biopsies from patients with asthma and isolated primary fibroblasts thereof. miR-142-3p was increased in hyperproliferative regions of lung in murine and human asthma, whereas this microRNA (miRNA) was excluded from regions with differentiated ASM cells. Increases in miR-142-3p were associated with a decrease of its known target Adenomatous polyposis coli. Furthermore, we observed a differential expression of miR-142-3p in bronchial biopsies from patients with early or late onset severe asthma, which coincided with a differential WNT signature. Our data suggest that miR-142-3p is involved in regulating the balance between proliferation and differentiation of ASM cells in asthma, possibly via controlling WNT signaling. Thus, this miRNA might be an interesting target to prevent ASM hyperproliferation in asthma.

Inflammatory biomarkers for asthma endotyping and consequent personalized therapy

We argue that asthma be considered a syndrome caused by multiple inflammatory pathogenic processes. Bronchial hyperresponsiveness, reversible airflow limitation, and chronic airway inflammation characterize asthma pathophysiology. Personalized Medicine, i.e. a tailored management approach, is appropriate for asthma management and is based on the identification of discrete phenotypes and endotypes. Biomarkers can help define phenotypes and endotypes. Several biomarkers have been described in asthma, but most of them are not commonly available or still need external validation. Areas covered: This review presents useful pragmatic biomarkers available in daily clinical practice for assessing airway inflammation in asthmatic patients. Expert commentary: Eosinophil counts and serum allergen-specific IgE assessments are the most reliable biomarkers. Lung function, mainly concerning FEF25-75, and nasal cytology may be envisaged as ancillary biomarkers in asthma management. In conclusion, biomarkers have a clinical relevance in asthma in identifying asthma endotypes to direct personalized therapy.

The Role of Dupilumab in Severe Asthma

Dupilumab is a fully humanized monoclonal antibody, capable of inhibiting intracellular signaling of both interleukin (IL)-4 and IL-13. These are two molecules that, together with other proinflammatory cytokines such as IL-5 and eotaxins, play a pivotal role in orchestrating the airway inflammatory response defined as Type 2 (T2) inflammation, driven by Th2 or Type 2 innate lymphoid cells, which is the major feature of the T2 high asthma phenotype. The dual inhibition of IL-4 and IL-13 activities is due to the blockade of type II IL-4 receptor through the binding of dupilumab with the subunit IL-4Rα. This results in the repression of STAT6 and in the suppression of subsequent de novo formation of several molecules involved in the T2 inflammatory signature. Several clinical trials tested the efficacy and safety of dupilumab in large populations of uncontrolled severe asthmatics, revealing significant improvements in lung function, asthma control, and exacerbation rate. Similar results were reported when dupilumab was employed in patients harboring pathogenetic processes related to T2 immune response, such as atopic dermatitis and chronic rhinosinusitis. In this review, we provide an overview of the recent research in the field of respiratory medicine about dupilumab mechanism of action and its effects.

Proliferation and inflammation in bronchial epithelium after allergen in atopic asthmatics

BACKGROUND

The mechanisms that regulate epithelial integrity and repair in asthma are poorly understood. We hypothesized that allergen exposure could alter epithelial inflammation, damage and proliferation in atopic asthma.

OBJECTIVE

We studied epithelial cell infiltration, shedding, expression of the proliferation marker Ki-67 and the epithelial cell-cell adhesion molecules Ep-CAM and E-cadherin in bronchial biopsies of 10 atopic mild asthmatics 48 h after experimental diluent (D) and allergen (A) challenge in a cross-over design.

METHODS

Epithelial shedding, expressed as percentage of not intact epithelium, Ki-67+, eosinophil/EG-2+, CD4+ and CD8+ cells were quantified by image analysis in bronchial epithelium, and adhesion molecules were analysed semi-quantitatively.

RESULTS

Epithelial shedding was not altered by A (D: 88.1+/-3.1% vs. A: 89.2+/-3.7%; P=0.63). The numbers of Ki-67+ epithelial (D: 10.2+/-0.2 vs. A: 19.9+/-0.3 cells/mm; P=0.03), EG-2+ (D: 4.3+/-0.5 vs. A: 27+/-0.3 cells/mm; P=0.04) and CD4+ cells (D: 1.7+/-1.2 vs. A: 12.3+/-0.6 cells/mm; P=0.04) were significantly increased after A, whilst CD8+ numbers were not significantly changed (P>0.05). E-cadherin and Ep-CAM epithelial staining showed a similar intensity after D and A (P>0.05). We found a positive correlation between EG-2+ and Ki-67+ cells in the epithelium (Rs: 0.63; P=0.02).

CONCLUSION

Our study indicates that allergen challenge increases epithelial proliferation in conjunction with inflammation at 2 days after exposure. This favours the hypothesis that long-lasting epithelial restitution is involved in the pathogenesis of asthma.

Critical evaluation of asthma biomarkers in clinical practice

The advent of personalized medicine has revolutionized the whole approach to the management of asthma, representing the essential basis for future developments. The cornerstones of personalized medicine are the highest precision in diagnosis, individualized prediction of disease evolution, and patient-tailored treatment. To this aim, enormous efforts have been established to discover biomarkers able to predict patients' phenotypes according to clinical, functional, and bio-humoral traits. Biomarkers are objectively measured characteristics used as indicators of biological or pathogenic processes or clinical responses to specific therapeutic interventions. The diagnosis of type-2 asthma, prediction of response to type-2 targeted treatments, and evaluation of the risk of exacerbation and lung function impairment have been associated with biomarkers detectable either in peripheral blood or in airway samples. The surrogate nature of serum biomarkers, set up to be less invasive than sputum analysis or bronchial biopsies, has shown several limits concerning their clinical applicability. Routinely used biomarkers, like peripheral eosinophilia, total IgE, or exhaled nitric oxide, result, even when combined, to be not completely satisfactory in segregating different type-2 asthma phenotypes, particularly in the context of severe asthma where the choice among different biologics is compelling. Moreover, the type-2 low fraction of patients is not only an orphan of biological treatments but is at risk of being misdiagnosed due to the low negative predictive value of type-2 high biomarkers. Sputum inflammatory cell analysis, considered the highest specific biomarker in discriminating eosinophilic inflammation in asthma, and therefore elected as the gold standard in clinical trials and research models, demonstrated many limits in clinical applicability. Many factors may influence the measure of these biomarkers, such as corticosteroid intake, comorbidities, and environmental exposures or habits. Not least, biomarkers variability over time is a confounding factor leading to wrong clinical choices. In this narrative review, we try to explore many aspects concerning the role of routinely used biomarkers in asthma, applying a critical view over the "state of the art" and contemporarily offering an overview of the most recent evidence in this field.

Exhaled nitric oxide may predict bronchial hyperreactivity in patients with allergic rhinitis

BACKGROUND

Nowadays it is possible to assess airway inflammation by measuring the fractional concentration of exhaled nitric oxide (FeNO) during an office visit and there is international consensus on the testing methodology. The aim of this study was to evaluate whether FeNO measurement may be a predictor of bronchial hyperreactivity (BHR) in patients with allergic rhinitis (AR).

METHODS

Two hundred eleven patients (196 males, median age 28.5 years) suffering from persistent AR were evaluated. Values for bronchial function (FVC, FEV(1), and FEF(25-75)), bronchial provocation tests (methacholine), exhaled nitric oxide (FeNO), a visual analogue scale for nasal and bronchial symptoms, and sensitization were assessed.

RESULTS

A strong and inverse correlation between FeNO levels and BHR severity was found (r = -0.58). FeNO was a predictive factor for BHR, and 37 ppb was found to be the best cutoff (area under the curve 0.90) to define the presence of BHR in patients with AR.

CONCLUSIONS

This study highlights the relevance of FeNO as a possible predictive marker for BHR in AR patients and underlines the close link between upper and lower airways. Thus, FeNO measurement could be a useful screening tool in identifying subjects with rhinitis at risk of developing asthma.

Effect of bradykinin on allergen induced increase in exhaled nitric oxide in asthma

BACKGROUND

Exposure of patients with atopic asthma to allergens produces a long term increase in exhaled nitric oxide (FENO), probably reflecting inducible NO synthase (NOS) expression. In contrast, bradykinin (BK) rapidly reduces FENO. It is unknown whether BK suppresses increased FENO production after allergen exposure in asthma, and whether it modulates FENO via NOS inhibition.

METHODS

Levels of FENO in response to aerosolised BK were studied before (day 3) and 48 hours after (day 10) randomised diluent (diluent/placebo/BK (Dil/P/BK)), allergen (allergen/placebo/BK (All/P/BK), and allergen/L-NMMA/BK (All/L/BK)) challenges (day 8) in 10 atopic, steroid naïve, mild asthmatic patients with dual responses to inhaled house dust mite extract. To determine whether BK modulates FENO via NOS inhibition, subjects performed pre- and post-allergen BK challenges after pretreatment with the NOS inhibitor L-NMMA in the All/L/BK period.

RESULTS

Allergen induced a fall in FENO during the early asthmatic reaction (EAR) expressed as AUC(0-1) (ANOVA, p=0.04), which was followed by a rise in FENO during the late asthmatic reaction (LAR) expressed as AUC(1-48) (ANOVA, p=0.008). In the Dil/P/BK period, FENO levels after BK on pre- and post-diluent days were lower than FENO levels after placebo (difference 23.5 ppb (95% CI 6.2 to 40.9) and 22.5 ppb (95% CI 7.3 to 37.7), respectively; p<0.05). Despite the long lasting increase in FENO following allergen challenge in the LAR, BK suppressed FENO levels at 48 hours after allergen challenge in the All/P/BK period, lowering the increased FENO (difference from placebo 54.3 ppb (95% CI 23.8 to 84.8); p=0.003) to the baseline level on the pre-allergen day (p=0.51). FENO levels were lower after L-NMMA than after placebo on pre-allergen (difference 10.85 ppb (95% CI 1.3 to 20.4); p=0.03) and post-allergen (difference 36.2 ppb (95% CI 5.5 to 66.9); p=0.03) days in the All/L/BK and All/P/BK periods, respectively. L-NMMA did not significantly potentiate the pre- and post-allergen reduction in BK induced FENO.

CONCLUSIONS

Bradykinin suppresses the allergen induced increase in exhaled NO in asthma; this is not potentiated by L-NMMA. Bradykinin and L-NMMA may follow a common pathway in reducing increased NO production before and after experimental allergen exposure. Reinforcement of this endogenous protective mechanism should be considered as a therapeutic target in asthma.

Fractional Exhaled Nitric Oxide: A Potential Biomarker in Allergic Rhinitis?

BACKGROUND

The fractional concentration of exhaled nitric oxide (FeNO) is a surrogate biomarker for Th2-dependent bronchial inflammation. The present study investigated whether FeNO may characterize allergic rhinitis (AR) patients.

METHODS

A total of 553 AR patients (497 males, mean age 28.8 years) were evaluated. Those patients with a high FeNO underwent a 2-year follow-up.

RESULTS

Increased FeNO was associated with a significantly longer AR duration, impaired lung function, more severe symptoms, and more frequent bronchial hyperresponsiveness (BHR). At follow-up, 22 out of 82 patients (26.8%) with high FeNO levels (>50 ppb) developed asthma.

CONCLUSIONS

AR patients may frequently have high FeNO values, exceeding 50 ppb. This might be associated with an initial impaired lung function, BHR, a perceived worsening of respiratory symptoms, and potential progression to asthma.

The Combined Impact of Exhaled Nitric Oxide and Sputum Eosinophils Monitoring in Asthma Treatment: A Prospective Cohort Study

BACKGROUND

Inhaled corticosteroids (ICS) treatment for asthma control is generally focused on lung function and symptoms, but inadequately correlated with airway inflammation.

OBJECTIVE

To compare asthma control in a group of patients whose treatment was based on fraction of exhaled nitric oxide (FENO) and sputum eosinophils (intervention group) with a group in whom treatment was based on clinical score (control group). Study design and primary outcome: Randomized parallel-group longitudinal 24-month study including 5 visits every 6 months. A combination of asthma exacerbation rate and symptom score at 24 months was the primary outcome.

PARTICIPANTS

Fourteen patients with eosinophilic asthma per group were included.

RESULTS

In the intervention group, exacerbation rate/patient/year was reduced at 12 months (0.82) (-73%) and, to a greater extent at 24 months (0.5) (-84%) compared with baseline (3.21, p<0.01). In the control group, a significant reduction in exacerbation rate/patient/year was only observed between month 12 (3.0) and 24 (2.0, -33%, p<0.01). At 24 months, exacerbation rate was lower (-75%) in the intervention (0.5) than in the control group (2.0, p<0.05). Compared with baseline, mean symptom scores at 24 months were reduced in both groups (intervention group: -72%; control group: - 60%), but were lower in the intervention (8.1±1.0, p<0.05; -27%) than in the control group (11±2.6). ICS dose gradually increased in both groups throughout the study, with no between-group differences.

CONCLUSION

Compared with conventional strategy, longitudinal monitoring of FENO and sputum eosinophils improves eosinophilic asthma control in terms of reduced symptoms and exacerbations without additional increase e in ICS treatment.

Nasal nitric oxide is a marker of poor asthma control

Asthma control, evaluated by symptoms, exacerbations rate and lung function may be greatly influenced by comorbidities, particularly chronic rhinosinusitis (CRS). Measurement of nasal nitric oxide (nNO) is a simple way to assess the severity of CRS. We aimed to analyze the relationship between asthma control and nasal NO. All patients with moderate-to-severe asthma on regular follow-up at our Outpatients' Clinic between November 2009 and April 2010 were included into the study. All patients were evaluated for asthma control by asthma control questionnaire (ACQ) and comorbidities (rhinitis, chronic rhinosinusitis with (CRSwNP) or without nasal polyps, obesity). Exhaled nitric oxide and nNO were obtained in all patients. Eighty-two patients were enrolled (mean age: 48 years, range: 21-80; 42 females). According to ACQ, 53 patients (64.6%) reported controlled asthma. Patients with uncontrolled asthma had lower nNO and higher prevalence of CRSwNP, with a significant correlation between nNO and ACQ. nNO is a biomarker negatively related to asthma control. As low nNO values were associated to CRSwNP, our results indicate that asthma control is highly influenced by this comorbidity.

Platelet activation and cardiovascular comorbidities in patients with chronic obstructive pulmonary disease

Objective Platelet activation in COPD patients is associated with an increased risk of cardiovascular events. We aimed at assessing the mean platelet volume (MPV), as an index of platelet activation, in COPD patients both when stable or during acute exacerbation (AE). Research design and methods A total of 478 patients (75 with AE) and 72 age-matched healthy controls were enrolled. Medical history, comorbidities, medications, pulmonary function tests, MPV and blood cell count, erythrocyte sedimentation rate (ERS) and C-reactive protein (CRP) were recorded. Results MPV was higher in COPD than in controls (8.7 ± 1.1 fL and 8.4 ± 0.8 fL respectively, p = 0.025) and increased with the severity of the disease as assessed by post-bronchodilator forced expiratory volume in the first second (FEV1) categorized I to IV (p > 0.05). MPV was higher in COPD patients during AE compared with stable condition (8.7 ± 1.0 fL and 8.9 ± 1.0 fL, p = 0.021). MPV ≥10.5 fL correlated with the presence of at least one co-existing cardiovascular disease (p = 0.008). No correlation was observed between MPV and CRP or ERS in patients or in controls. A negative correlation was found between platelet count and MPV in COPD patients. Limitations The retrospective design did not allow the assessment of a clear cause-effect relationship between MPV and all the pathophysiological factors considered. Conclusions Elevated MPV is associated with lower platelet count and with cardiovascular comorbidity in COPD patients. MPV is higher in more severe COPD and during AE. Present findings warrant future studies to confirm a possible clinically relevant role for platelet activation in cardiovascular risk in the COPD population.

Increased body mass index and bronchial impairment in allergic rhinitis

BACKGROUND

Several studies have outlined a possible relationship between an increased body mass index (BMI) and respiratory allergic diseases, such as asthma and allergic rhinitis (AR). The aim of this study was to analyze the relationship among BMI, spirometry, bronchial hyperreactivity (BHR), and fractional concentration of exhaled nitric oxide (FeNO) in a cohort of AR patients.

METHODS

The study included 155 patients with persistent AR alone and 155 healthy controls. All subjects were evaluated performing skin-prick test, spirometry, bronchoprovocation test with methacholine, and FeNO measurement.

RESULTS

BMI values were significantly higher in AR patients than in control subjects (p = 0.038). Overweight/obese AR patients had more altered functional and inflammatory parameters than normal weight patients. BMI > 25 is a risk factor for (i) early bronchial airflow limitation (odds ratio [OR], 3.81), (ii) high FeNO values (OR, 1.96), and BHR (OR, 3.29).

CONCLUSIONS

The present study may suggest that BMI assessment should be routinely considered in AR patients for assessing risk for early bronchial impairment, such as suggesting possible evolution to asthma.

Validated safety predictions of airway responses to house dust mite in asthma

BACKGROUND

House dust mite (HDM) is the most common aeroallergen causing sensitization in many Western countries and is often used in allergen inhalation challenges. The concentration of inhaled allergen causing an early asthmatic reaction [provocative concentration of inhaled allergen causing a 20% fall of forced expiratory volume in 1 s (FEV(1))(PC(20) allergen)] needs to be predicted for safety reasons to estimate accurately the severity of allergen-induced airway responsiveness. This can be accomplished by using the degree of non-specific airway responsiveness and skin sensitivity to allergen.

OBJECTIVE

We derived prediction equations for HDM challenges using PC(20) histamine or PC(20) methacholine and skin sensitivity data obtained from patients with mild to moderate persistent asthma and validated these equations in an independent asthma population.

METHODS

PC(20) histamine or PC(20) methacholine, skin sensitivity, and PC(20) allergen were collected retrospectively from 159 asthmatic patients participating in allergen challenge trials. Both the histamine and methacholine groups (n=75 and n=84, respectively), were divided randomly into a reference group to derive new equations to predict PC(20) allergen, and a validation group to test the new equations.

RESULTS

Multiple linear regression analysis revealed that PC(20) allergen could be predicted either from PC(20) methacholine only ((10)log PC(20) allergen=-0.902+0.741.(10)log PC(20) methacholine) or from PC(20) histamine and skin sensitivity (SS) ((10)log PC(20) allergen=-0.494+0.231.(10)log SS+0.546.(10)log PC(20) histamine). In the validation study, these new equations accurately predicted PC(20) allergen following inhalation of HDM allergen allowing a safe starting concentration of allergen of three doubling concentrations below predicted PC(20) allergen in all cases.

CONCLUSION

The early asthmatic response to inhaled HDM extract is predominantly determined by non-specific airway responsiveness to methacholine or histamine, whereas the influence of the cutaneous sensitivity to HDM appears to be rather limited. Our new equations accurately predict PC(20) allergen and hence are suitable for implementation in HDM inhalation studies.

Nitric oxide's physiologic effects and potential as a therapeutic agent against COVID-19

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for COVID-19 pneumonia, a pandemic that precipitates huge pressures on the world's social and economic systems. Disease severity varies among individuals. SARS-CoV-2 infection can be associated with e.g. flu-like symptoms, dyspnoea, severe interstitial pneumonia, acute respiratory distress syndrome, multiorgan dysfunction, and generalized coagulopathy. Nitric oxide (NO), is a small signal molecule that impacts pleiotropic functions in human physiology, which can be involved in the significant effects of COVID-19 infection. NO is a neurotransmitter involved in the neural olfactory processes in the central nervous system, and some infected patients have reported anosmia as a symptom. Additionally, NO is a well-known vasodilator, important coagulation mediator, anti-microbial effector and inhibitor of SARS-CoV replication. Exhaled NO is strongly related to the type-2 inflammatory response found in asthma, which has been suggested to be protective against SARS-CoV-2 infection. Several reports indicate that the use of inhaled NO has been an effective therapy during this pandemic since the ventilation-perfusion ratio in COVID-19 patients improved afterwards and they did not require mechanical ventilation. The aim of this mini-review is to summarize relevant actions of NO that could be beneficial in the treatment of COVID-19.

A real-world assessment of asthma with chronic rhinosinusitis

BACKGROUND

Chronic rhinosinusitis (CRS) includes 2 main phenotypes: CRS without nasal polyps (CRSsNP) and CRS with nasal polyps (CRSwNP). CRS has been reported to be a comorbidity of asthma.

OBJECTIVE

This study aimed to investigate the role of CRS in outpatients with asthma visited in real-world setting.

METHODS

This cross-sectional study enrolled 499 consecutive outpatients with asthma. Age, sex, body mass index, smoking status, lung function, Asthma Control Test, inflammatory type 2 biomarkers (including fractional exhaled nitric oxide, blood eosinophils, serum total immunoglobulin E, and allergy), treatment step according to the Global Initiative for Asthma, and comorbidities (obstructive sleep apnea syndrome, arterial hypertension, bronchiectasis, diabetes mellitus type 2, and osteoporosis) were evaluated.

RESULTS

A total of 179 (35.87%) patients had CRS, in particular 93 (18.64%) had CRSsNP and 86 (17.23%) had CRSwNP. Type 2 inflammation (defined by at least 1 positive biomarker) was present in 81.44% of patients (fractional exhaled nitric oxide > 30 parts per billion in 46.9%, blood eosinophil count > 300 cell/μL in 39.67%, serum total immunoglobulin E >100 IU/mL in 51.54%, and allergy in 53.71%). By multivariate analysis, type 2 inflammation and blood eosinophils greater than 300 cell/μL were the main predictors (odds ratio [OR] 2.54 and 2.26, respectively) of CRS-asthma association. In particular, CRSwNP comorbidity was predicted by type 2 inflammation (OR 3.4) and blood eosinophils greater than 300 cell/μL (OR 3.0). Smoking had conflicting outcome.

CONCLUSION

This study confirmed that CRS is a frequent asthma comorbidity because it affects more than one-third of outpatients with asthma. CRSwNP is associated with type 2 inflammation and blood eosinophilia. These outcomes underline that CRSwNP asthma phenotype deserves adequate attention for careful management and optimal identification of the best-tailored therapy.

Exhaled nitric oxide is related to bronchial eosinophilia and airway hyperresponsiveness to bradykinin in allergen-induced asthma exacerbation

Exhaled nitric oxide (FeNO) has been associated with bronchial eosinophilia and with airway hyperresponsiveness (AHR) in mild stable asthma. We previously demonstrated in a large project that allergen exposure is able to raise FeNO and to worsen AHR to bradykinin. We postulated that allergen-induced increase in FeNO could be related to heightened mucosal eosinophils and AHR to bradykinin in atopic asthma. We performed a new immunohistochemical analysis on bronchial biopsy specimens, previously obtained from the same large project, in order to assess the number of mucosal eosinophils (EG-2+ cell) and other inflammatory cells at 48 hours after diluent and allergen exposures. Inflammatory cell counts were related to FeNO and AHR to BK (expressed as logPD20 bradykinin). In 10 atopic mild asthmatics, we found that the numbers of EG-2+ and CD4+ cells in bronchial submucosa were significantly increased after allergen compared to the respective counts after diluent (p &#x003C; 0.01). EG-2+ cells in the bronchial submucosa were negatively correlated with logPD20 bradykinin only after allergen challenge (rho = -0.709, p = 0.027). We also found a positive strong correlation between EG-2+ cells and FeNO values in atopic asthmatics at 48 hours after both diluent (rho = 0.746, p = 0.017) and allergen (rho = 0.644, p = 0.049) challenge. FeNO values negatively correlated with responsiveness to bradykinin only after allergen challenge (rho = -0.675, p = 0.039). This study indicates that after allergen exposure heightened level of exhaled NO may reflect augmented airway eosinophilic inflammation and airway responsiveness to bradykinin indicating loss of asthma control.