Inflammatory events in asthma: an expanding equation

Cluster analysis of phenotypes, job exposure, and inflammatory patterns in elderly and nonelderly asthma patients

BACKGROUND

Asthma has been identified as different phenotypes due to various risk factors. Age differences may have potential effects on asthma phenotypes. Our study aimed to identify potential asthma phenotypes among adults divided by age as either younger or older than 65 years. We also compared differences in blood granulocyte patterns, occupational asthmagens, and asthma control-related outcomes among patient phenotype clusters.

METHODS

We recruited nonelderly (<65 years old) (n = 726) and elderly adults (≥65 years old) (n = 201) with mild-to-severe asthma. We conducted a factor analysis to select 17 variables. A two-step cluster analysis was used to classify subjects with asthma phenotypes, and a discriminant analysis was used to verify the classification of cluster results.

RESULTS

There were three clusters with different characteristics identified in both the nonelderly and elderly asthmatic adults. In the nonelderly patient group, cluster 2 (obese, neutrophilic phenotypes) had a 1.85-fold significantly increased risk of asthma exacerbations. Cluster 3 (early-onset, atopy, and smoker with an eosinophil-predominant pattern) had a 2.37-fold risk of asthma exacerbations and higher oral corticosteroid (OCS) use than cluster 1 (late-onset and LMW exposure with paucigranulocytic blood pattern). Among elderly patients, cluster 2 had poor lung function and more ex-smokers. Cluster 3 (early-onset, long asthma duration) had the lowest paucigranulocytic blood pattern percentages in the elderly group.

CONCLUSIONS

The novelty of the clusters was found in age-dependent clusters. We identified three distinct phenotypes with heterogeneous characteristics, asthma exacerbations and medicine use in nonelderly and elderly asthmatic patients, respectively. Classification of age-stratified asthma phenotypes may lead to precise identification of patients, which provides personalized disease management.

Single-cell analysis reveals alterations in cellular composition and cell-cell communication associated with airway inflammation and remodeling in asthma

BACKGROUND

Asthma is a heterogeneous disease characterized by airway inflammation and remodeling, whose pathogenetic complexity was associated with abnormal responses of various cell types in the lung. The specific interactions between immune and stromal cells, crucial for asthma pathogenesis, remain unclear. This study aims to determine the key cell types and their pathological mechanisms in asthma through single-cell RNA sequencing (scRNA-seq).

METHODS

A 16-week mouse model of house dust mite (HDM) induced asthma (n = 3) and controls (n = 3) were profiled with scRNA-seq. The cellular composition and gene expression profiles were assessed by bioinformatic analyses, including cell enrichment analysis, trajectory analysis, and Gene Set Enrichment Analysis. Cell-cell communication analysis was employed to investigate the ligand-receptor interactions.

RESULTS

The asthma model results in airway inflammation coupled with airway remodeling and hyperresponsiveness. Single-cell analysis revealed notable changes in cell compositions and heterogeneities associated with airway inflammation and remodeling. GdT17 cells were identified to be a primary cellular source of IL-17, related to inflammatory exacerbation, while a subpopulation of alveolar macrophages exhibited numerous significantly up-regulated genes involved in multiple pathways related to neutrophil activities in asthma. A distinct fibroblast subpopulation, marked by elevated expression levels of numerous contractile genes and their regulators, was observed in increased airway smooth muscle layer by immunofluorescence analysis. Asthmatic stromal-immune cell communication significantly strengthened, particularly involving GdT17 cells, and macrophages interacting with fibroblasts. CXCL12/CXCR4 signaling was remarkedly up-regulated in asthma, predominantly bridging the interaction between fibroblasts and immune cell populations. Fibroblasts and macrophages could jointly interact with various immune cell subpopulations via the CCL8/CCR2 signaling. In particular, fibroblast-macrophage cell circuits played a crucial role in the development of airway inflammation and remodeling through IL1B paracrine signaling.

CONCLUSIONS

Our study established a mouse model of asthma that recapitulated key pathological features of asthma. ScRNA-seq analysis revealed the cellular landscape, highlighting key pathological cell populations associated with asthma pathogenesis. Cell-cell communication analysis identified the crucial ligand-receptor interactions contributing to airway inflammation and remodeling. Our findings emphasized the significance of cell-cell communication in bridging the possible causality between airway inflammation and remodeling, providing valuable hints for therapeutic strategies for asthma.

Nicotinic receptors in airway disease

With continued smoking of tobacco products and expanded use of nicotine delivery devices worldwide, understanding the impact of smoking and vaping on respiratory health remains a major global unmet need. Although multiple studies have shown a strong association between smoking and asthma, there is a relative paucity of mechanistic understanding of how elements in cigarette smoke impact the airway. Recognizing that nicotine is a major component in both smoking and vaping products, it is critical to understand the mechanisms by which nicotine impacts airways and promotes lung diseases such as asthma. There is now increasing evidence that α7 nicotinic acetylcholine receptors (α7nAChRs) are critical players in nicotine effects on airways, but the mechanisms by which α7nAChR influences different airway cell types have not been widely explored. In this review, we highlight and integrate the current state of knowledge regarding nicotine and α7nAChR in the context of asthma and identify potential approaches to alleviate the impact of smoking and vaping on the lungs.

Alpha-1 Asthma Overlap Syndrome: a Clinical Overview

PURPOSE OF REVIEW

Alpha-1 antitrypsin deficiency (AATD) is one of the most common genetic diseases that is associated with severe complications and yet remains underdiagnosed. The pulmonary symptoms of both AATD and asthma include cough, excessive sputum production, dyspnea, and wheezing. These symptoms overlap significantly leading to difficulty distinguishing between these two conditions and suspicion that there may be an overlap syndrome. We aim to discuss the pathophysiology, clinical manifestations, and treatment of both alpha-1 antitrypsin and asthma and how they may overlap.

RECENT FINDINGS

Recent literature suggests that there is an association between asthma and AATD. This association has been hypothesized to be secondary to an imbalance of elastase and anti-elastase leading to a pro-inflammatory state in patients with AATD. This review serves to overview the pathophysiology, clinical manifestations, and treatment of alpha-1 antitrypsin, asthma, and the increasingly recognized intersection of the two, AATD-asthma overlap syndrome.

Comparative effects of capsaicin in chronic obstructive pulmonary disease and asthma (Review)

Chronic obstructive pulmonary disease (COPD) and asthma are chronic respiratory diseases with high prevalence and mortality that significantly alter the quality of life in affected patients. While the cellular and molecular mechanisms engaged in the development and evolution of these two conditions are different, COPD and asthma share a wide array of symptoms and clinical signs that may impede differential diagnosis. However, the distinct signaling pathways regulating cough and airway hyperresponsiveness employ the interaction of different cells, molecules, and receptors. Transient receptor potential cation channel subfamily V member 1 (TRPV1) plays a major role in cough and airway inflammation. Consequently, its agonist, capsaicin, is of substantial interest in exploring the cellular effects and regulatory pathways that mediate these respiratory conditions. Increasingly more studies emphasize the use of capsaicin for the inhalation cough challenge, yet the involvement of TRPV1 in cough, bronchoconstriction, and the initiation of inflammation has not been entirely revealed. This review outlines a comparative perspective on the effects of capsaicin and its receptor in the pathophysiology of COPD and asthma, underlying the complex entanglement of molecular signals that bridge the alteration of cellular function with the multitude of clinical effects.

Asthma: New Integrative Treatment Strategies for the Next Decades

Asthma is a chronic disease whose main anatomical-functional alterations are grouped into obstruction, nonspecific bronchial hyperreactivity, inflammation and airway remodeling. Currently, the Global Initiative of Asthma 2020 (GINA 2020) suggests classifying it into intermittent cases, slightly persistent, moderately persistent and severely persistent, thus determining the correct guidelines for its therapy. In general, the drugs used for its management are divided into two groups, those with a potential bronchodilator and the controlling agents of inflammation. However, asthmatic treatments continue to evolve, and notable advances have been made possible in biological therapy with monoclonal antibodies and in the relationship between this disease and oxidative stress. This opens a new path to dietary and herbal strategies and the use of antioxidants as a possible therapy that supports conventional pharmacological treatments and reduces their doses and/or adverse effects. This review compiles information from different published research on risk factors, pathophysiology, classification, diagnosis and the main treatments; likewise, it synthesizes the current evidence of herbal medicine for its control. Studies on integrative medicine (IM) therapies for asthmatic control are critically reviewed. An integrative approach to the prevention and management of asthma warrants consideration in clinical practice. The intention is to encourage health professionals and scientists to expand the horizons of basic and clinical research (preclinical, clinical and integrative medicine) on asthma control.

Sex-Specific Asthma Phenotypes, Inflammatory Patterns, and Asthma Control in a Cluster Analysis

BACKGROUND

Asthma is a heterogeneous disease with complex mechanisms and involves many risk factors and in vivo cellular molecules. It is notable that sex differences may have a potential effect on asthma phenotype.

OBJECTIVE

To identify sex-specific phenotypes and health outcomes of asthma.

METHODS

We conducted the Taiwanese Adult Asthma Cohorts study to enroll female (n = 421) and male (n = 299) adult patients with stable asthma. Eight variables were selected by a factor analysis. We further performed a 2-step sensitivity cluster analysis to classify asthma clusters. The risks of asthma-related outcomes among the clusters were assessed using simple logistic regressions.

RESULTS

Three different clusters were identified in males and females. In the female clusters, atopy/eosinophil-predominant (cluster 2), and obesity/neutrophil-predominant pattern (cluster 3) had more than a 2-fold risk of asthma exacerbations (odds ratio, 2.51; 95% CI, 1.12-5.59 and odds ratio, 2.22; 95% CI, 1.01-4.93). In the male clusters, current smoker/neutrophilic atopic cluster (cluster 5) and ex-smoker/eosinophil-predominant or mixed inflammatory pattern (cluster 6) also had a higher risk of asthma exacerbations.

CONCLUSIONS

This study identified heterogeneous characteristics between sexes. In females, the analysis showed atopy with eosinophil-predominant and obese with neutrophil-predominant inflammation. Two distinct asthma phenotypes were found in current and ex-smokers in males. Understanding asthma phenotypes and explaining the potentially biological pathways have become important.

Full blood count parameters for the detection of asthma inflammatory phenotypes

BACKGROUND

In asthma, the airway inflammatory phenotype influences clinical characteristics and treatment response. Although induced sputum is the gold standard test for phenotyping asthma, a more accessible method is needed for clinical practice.

OBJECTIVE

To investigate whether white blood cell counts and/or their derived ratios can predict sputum eosinophils or neutrophils in uncontrolled asthma.

METHODS

This cross-sectional study evaluated 164 treated but uncontrolled asthmatic patients with sputum induction and blood collection. Receiver-operating characteristic (ROC) curves were used to assess the relationship between blood and sputum parameters.

RESULTS

There was a significant positive relationship between blood eosinophil parameters and the percentage of sputum eosinophil count. A weak but significant correlation was found between sputum neutrophil percentage and blood neutrophil percentage (r = 0.219, P = 0.005). ROC curve analysis identified that blood eosinophil percentage count was the best predictor for eosinophilic asthma, with an area under the curve (AUC) of 0.907 (P < 0.001). The optimum cut-point for blood eosinophil percentage was 2.7%, and this yielded a sensitivity of 92.2% and a specificity of 75.8%. The absolute blood eosinophil count was also highly predictive with an AUC of 0.898 (P < 0.0001) at a blood eosinophil cut-off of 0.26 × 10(9) /L. The blood eosinophil/lymphocyte ratio (ELR) and eosinophil/neutrophil ratio (ENR) were increased in eosinophilic asthma, and the neutrophil/lymphocyte ratio (NLR) was increased in neutrophilic asthma. Neutrophilic asthma could also be detected by blood neutrophil percentages and NLR, but with less accuracy.

CONCLUSIONS AND CLINICAL RELEVANCE

Blood eosinophil counts and derived ratios (ELR and ENR) can accurately predict eosinophilic asthma in patients with persistent uncontrolled asthma despite treatment. Blood neutrophil parameters are poor surrogates for the proportion of sputum neutrophils. Blood counts may be a useful aid in the monitoring of uncontrolled asthma.

Evaluation of propolis, honey, and royal jelly in amelioration of peripheral blood leukocytes and lung inflammation in mouse conalbumin-induced asthma model

Bee products have been used since ancient times to treat many diseases, including respiratory ailments. The present study aimed to examine the modulatory effect of honey, royal jelly, and propolis extract on peripheral blood leukocytes and lung inflammation in a mouse conalbumin-induced asthma model. The mice in group I were not sensitised or treated; they were kept as controls. The mice in group II were sensitised and challenged with conalbumin. Twenty-four hours after the first challenge with antigen, the mice in group III received 0.5 mg/kg of dexamethasone intraperitoneally per day for 18 consecutive days and kept as positive controls. The mice in groups IV, V, and VI received 650, 1000, and 30 mg/kg of honey, royal jelly, and propolis (aqueous and ethanolic extract), respectively, once per day for 18 consecutive days. Blood was collected from all of the mice for white blood cell differentiation, and the lungs were removed for histopathological studies. The groups treated with propolis extract exhibited considerable ameliorative effects against asthma, which might be explained by the flavonoids and phenolics found in propolis, which might have antioxidative effects. Otherwise, the sensitised and honey- or royal jelly-treated groups exhibited an increased incidence of asthma cascade events due to increased inflammatory cells. These results might be due to the immunostimulatory and vasodilatory effects of royal jelly and honey, which are antagonistic to bronchial asthma cases. Histopathological examination revealed that the sensitised treated propolis extract groups had significant decreases in inflammatory scores compared with other treatments and the sensitised untreated group. These results confirmed the previous data of peripheral blood cells.

Poly(ADP-ribose) polymerase inhibition with HYDAMTIQ reduces allergen-induced asthma-like reaction, bronchial hyper-reactivity and airway remodelling

Activation of poly(ADP-ribose) polymerases (PARPs) is considered a key event in the molecular and cellular processes leading from acute asthma attacks to bronchial hyper-reactivity, leucocyte recruitment, chronic inflammation, airway remodelling and lung damage. The present investigation has been carried out to investigate the action of hydroxyl-dimethylaminomethyl-thieno[2,3-c]isoquinolin-5(4H)-one (HYDAMTIQ), a new potent PARP inhibitor, in the process leading from asthma-like events to airway damage. Ovalbumin-sensitized guinea pigs exposed two times to allergen inhalation were treated for 8 days with vehicle or HYDAMTIQ. Asthma-like signs, bronchial hyper-reactivity to methacholine, cytokine production, histamine release from mast cells, airway remodelling, collagen deposition and lung damage were evaluated. Repeated HYDAMTIQ administration (1-10 mg/kg/day i.p.) reduced lung PARP activity, delayed the appearance and reduced the severity of allergen-induced cough and dyspnoea and dampened the increased bronchial responses to methacholine. HYDAMTIQ-treated animals presented reduced bronchial or alveolar abnormalities, lower number of eosinophils and other leucocytes in the lung and decreased smooth muscle or goblet cell hyperplasia. The treatment also reduced lung oxidative stress markers, such as malondialdehyde or 8-hydroxy-2′-deoxyguanosine and the lung content of pro-inflammatory cytokines (TNF-α, interleukin (IL)-1β, IL-5, IL-6 and IL-18). Finally, mast cells isolated from the peritoneal or pleural cavities of sensitized, HYDAMTIQ-treated animals had a reduced ability to release histamine when exposed to ovalbumin in vitro. Our findings support the proposal that PARP inhibitors could have a therapeutic potential to reduce chronic lung inflammation, airway damage and remodelling in severe unresponsive asthmatic patients.

Targeting G protein-coupled receptor signaling in asthma

The complex disease asthma, an obstructive lung disease in which excessive airway smooth muscle (ASM) contraction as well as increased ASM mass reduces airway lumen size and limits airflow, can be viewed as a consequence of aberrant airway G protein-coupled receptor (GPCR) function. The central role of GPCRs in determining airway resistance is underscored by the fact that almost every drug used in the treatment of asthma directly or indirectly targets either GPCR-ligand interaction, GPCR signaling, or processes that produce GPCR agonists. Although many airway cells contribute to the regulation of airway resistance and architecture, ASM properties and functions have the greatest impact on airway homeostasis. The theme of this review is that GPCR-mediated regulation of ASM tone and ASM growth is a major determinant of the acute and chronic features of asthma, and multiple strategies targeting GPCR signaling may be employed to prevent or manage these features.

Asthma and risk of death from lung cancer: NHANES II Mortality Study

OBJECTIVE

Although smoking is the most important risk factor for lung cancer, nearly 10% of lung cancer is not attributable to smoking. Insights into risk factors for lung cancer other than smoking will become increasingly important, given decreasing trends in the prevalence of smoking. Prior research suggests asthma may increase the risk of lung cancer, particularly among nonsmokers.

METHODS

We used Cox regression analyses of data from a nationally representative sample of 9087 adults aged 30-75 years included in the NHANES II Mortality Study (1976-1992) to estimate the relative risk (RR) of death from lung cancer associated with self-reported asthma, independent of smoking.

RESULTS

Age-adjusted prevalence of smoking was 36.0%, and the age-adjusted prevalence of asthma was 6.1% (6.2% among nonsmokers) at baseline. During approximately 17 years of follow-up, 196 adults died of lung cancer (ICD-9 160-165). Among 6144 nonsmokers, the RR of lung cancer death comparing adults with asthma to those without was 1.69 (95% CI: 0.94-3.04) although the association was not statistically significant. For nonsmokers without a history of cancer, the RR was 2.53 (95% CI: 1.42-4.52). After exclusion of adults with emphysema and chronic bronchitis, the RR of lung cancer death associated with asthma was 3.54 (95% CI: 1.93-6.42).

CONCLUSIONS

Consistent with prior reports, we observed an increased risk of lung cancer mortality associated with asthma among nonsmokers without a history of cancer.

Shock, inflammation and PARP

The activation of poly(ADP-ribose) polymerase (PARP) is well considered to play an important role in various patho-physiological conditions like inflammation and shock. A vast amount of circumstantial evidence implicates oxygen-derived free radicals (especially, superoxide and hydroxyl radical) and high-energy oxidants (such as peroxynitrite) as mediators of inflammation and shock. ROS (e.g., superoxide, peroxynitrite, hydroxyl radical and hydrogen peroxide) are all potential reactants capable of initiating DNA single strand breakage, with subsequent activation of the nuclear enzyme poly(ADP-ribose) synthetase (PARS), leading to eventual severe energy depletion of the cells, and necrotic-type cell death. During the last years, numerous experimental studies have clearly demonstrated the beneficial effects of PARP inhibition in cell cultures through rodent models and more recently in pre-clinical large animal models of acute and chronic inflammation. The aim of this review is to describe recent experimental evidence implicating PARP as a pathophysiological modulator of acute and chronic inflammation.

Inhibition of poly(ADP-ribose) polymerase prevents allergen-induced asthma-like reaction in sensitized Guinea pigs

Poly(ADP-ribose) polymerase (PARP) plays an important role in tissue injury in conditions associated with oxidative stress and inflammation. Because asthma is a chronic inflammatory disorder of the airways, we designed the present experimental study to evaluate the effects of PARP inhibition on allergen-induced asthma-like reaction in ovalbumin-sensitized guinea pigs. Cough and dyspnea in response to ovalbumin aerosol were absent in naive guinea pigs, whereas they became severe in the sensitized animals. In the latter ones, ovalbumin aerosol also induced a rapid increase in PARP activity, bronchiolar constriction, pulmonary air space inflation, mast cell degranulation, poly(ADP-ribose) and nitrotyrosine immunostaining, myeloperoxidase activity, and malondialdehyde in lung tissue, as well as a rise in the amounts of nitrites and tumor necrosis factor-alpha in bronchoalveolar lavage fluid. Pretreatment with the PARP inhibitors 3-aminobenzamide (10 mg/kg b.wt.) or 5-aminoisoquinolinone (0.5 mg/kg b.wt.) given i.p. 3 h before ovalbumin challenge significantly reduced the severity of cough and the occurrence of dyspnea and delayed the onset of respiratory abnormalities. Both PARP inhibitors were also able to prevent the above morphological and biochemical changes of lung tissue or bronchoalveolar lavage fluid induced by ovalbumin challenge. Conversely, p-aminobenzoic acid, the inactive analog of 3-aminobenzamide, had no effects.

Medication use in athletes selected for doping control at the Sydney Olympics (2000)

During the Olympic Games held in Sydney in September, 2000 Doping Control was undertaken as specified in the International Olympic Code. During this process information about the medications taken by athletes was collected as a routine and formed part of the paperwork associated with a urine test. In their Post Games Report the World Anti-Doping Agency (WADA) recommended that the information about medications be collated with a view to assessing their use by athletes. Mandatory doping control for winners of events as well as random selection of athletes both during competition and out of competition allowed data to be collected about medications and supplements used by athletes. At the Doping Control Stations all competitors selected for a test, after providing a urine sample for analysis, were asked the same question: "what medications have you taken in the past three days?" The answer was to include all prescription drugs, over-the-counter medications, any other substances taken by mouth, injection, inhalation, ointment or by suppository, as well as vitamins, minerals, and all other supplements. This paper reviews the data from the 2758 Declaration Forms obtained at doping control. The prevalence of use of medications, the number used by an individual, and the pattern of use by these elite sports people were examined. The trends seen in this survey point to a dangerous overuse of nonsteroidal anti-inflammatory agents and an unnecessary overuse of vitamins in this population, while pointing out the increased prevalence of asthma and the dangers of drug interactions.

OBJECTIVE

The main objective here is to review some of the medications used by athletes in the Olympic Games in Sydney 2000.

DATA SOURCES

During these Games Doping Control was undertaken as specified by the International Olympic Committee. As well as a urine test, information about medications routinely taken was collected. Mandatory doping control for winners of events as well as random selection of athletes both during competition and out of competition required data to be collected about medications and supplements used by athletes as part of the sample collection protocol. At the Doping Control Stations all competitors selected for a test, after providing a urine sample for analysis, were asked the same question: "what medications have you taken in the past three days?" The answer was to include all prescription drugs, over-the-counter medications, any other substances taken by mouth, injection, inhalation, ointment or by suppository, as well as vitamins, minerals, and all other supplements.

DATA SELECTION

In this article we review the data from the laboratory copy of the 2758 Declaration Forms obtained at doping control. The cut down version of the Declaration Form submitted to the laboratory had all information identifying the athlete removed. Thus all information used in this article is completely anonymous. The prevalence of use of medications, the number used by an individual, and the pattern of use by these elite sports people were examined at the request of the IOC.

CONCLUSIONS

In their Post-Games Report, the World Anti-Doping Agency (WADA) acting as independent observers of the anti-doping process recommended to the IOC that the information obtained in the Athlete Declaration Forms concerning medications be collated with a view to assessing their use by athletes. The trends in their use seen in this survey point to an overuse of supplements as well as a dangerous overuse of drugs such as nonsteroidal anti-inflammatory agents together with multiple drug use emphasising the dangers of drug interactions and points out the increased prevalence of asthma in this population.

Inhaled mometasone furoate: a review of its use in adults and adolescents with persistent asthma

Mometasone furoate is a corticosteroid with relatively high in vitro potency. Recent randomised, double-blind, multicentre trials have assessed the efficacy of mometasone furoate delivered by dry powder inhaler over 12 weeks in adults and adolescents with mild to severe persistent asthma. Mometasone furoate 200 microg twice daily or 400 microg once daily in the morning or 200 microg once daily in the evening improved lung function, asthma symptom scores and use of rescue medication to a significantly greater extent than placebo in patients who had previously received only short-acting inhaled beta2-adrenoceptor agonists alone as treatment in 3 trials (n = 195 to 306). In studies in 227 to 733 patients with mild to moderate asthma who were receiving ongoing treatment with inhaled corticosteroids prior to enrolment, mometasone furoate 100 to 400 microg twice daily was consistently better at improving the above indicators of asthma than placebo. Mometasone furoate 100 to 200 microg twice daily was as effective as beclomethasone dipropionate 200 microg twice daily or budesonide 400 microg twice daily and mometasone furoate 200 microg twice daily was as effective as fluticasone propionate 250 microg twice daily. Mometasone furoate 400 or 800 microg twice daily was also consistently more effective than placebo in reducing oral corticosteroid dosages and improving lung function and asthma symptoms in 132 patients with oral corticosteroid-dependent asthma. Once daily administration of mometasone furoate 400 microg appears to be as effective at improving indicators of asthma as twice daily administration of 200 microg. Patients receiving mometasone furoate < or =800 microg/day and recipients of placebo experienced a similar overall incidence of adverse events considered to be related to treatment. The most common of these events were oral candidiasis, headache, pharyngitis and dysphonia. Mometasone furoate 100 to 400 microg twice daily, beclomethasone dipropionate 200 microg twice daily, budesonide 400 microg twice daily or fluticasone propionate 250 microg twice daily were similarly tolerated.

CONCLUSION

Inhaled mometasone furoate is well tolerated, with minimal systemic activity and is equally effective when administered as a divided dose or as a single daily dose. Use of the drug can result in a decrease in requirements for oral corticosteroids in patients with oral corticosteroid-dependent asthma and is as effective as other inhaled corticosteroids currently used in the treatment of mild to moderate persistent asthma. Thus mometasone furoate is suitable for the control of mild to severe persistent asthma in adults or adolescents.

Measurement of airway inflammation in asthma

Chronic airway inflammation is considered responsible for symptoms and disorders of airway function associated with asthma. This process is the target of anti-inflammatory therapy, so a number of standardized, noninvasive techniques have been developed to assess it. More recent approaches include the measurement of exhaled gases and nonvolatile substances in breath condensate. Results from studies using a wide variety of inflammatory markers have shown group differences between patients with asthma and healthy control subjects, but evidence for the diagnostic use of these markers in individual patients is scarce. Similarly, despite many studies demonstrating some correlation between markers of airway inflammation and a measure of disease control, none has yet convincingly shown a place for the use of these markers in an individual with corticosteroid-treated asthma. However, application of these markers continues to further our understanding of the disease process and provides the potential for more appropriate, customized therapy.

Extended allergen exposure in asthmatic monkeys induces neuroplasticity in nucleus tractus solitarius

BACKGROUND

Extended exposure to allergen exacerbates asthma symptoms, in part via complex interactions between inflammatory cells and mediators. One consequence of these interactions is the triggering of local and central nervous system (CNS) neuronal activity that might further exacerbate the asthma-like symptoms by causing bronchoconstriction, mucous secretion, increased microvascular leak, and cough. One CNS region that might be particularly important is the caudomedial nucleus tractus solitarius (NTS). NTS neurons not only integrate primary afferent inputs from lung sensory nerve fibers but also have direct exposure to inhaled allergens and allergen-induced blood-borne inflammatory mediators via a deficient blood-brain barrier. Given the capacity of CNS neurons to undergo plasticity, allergen-induced changes in NTS neuronal properties could contribute to the exaggerated respiratory responses to extended allergen exposure.

OBJECTIVE

In a recently developed rhesus monkey model of allergic asthma, we tested the hypothesis that extended exposure to allergen increases the intrinsic excitability of NTS neurons.

METHODS

Three adult monkeys were sensitized and then repeatedly exposed to aerosols of house dust mite allergen; 4 monkeys served as controls. Whole-cell current-clamp recordings were made to measure 3 indices of excitability: resting membrane potential, input resistance, and number of action potentials evoked by current injections.

RESULTS

Extended allergen exposure depolarized the resting membrane potential by 14% and increased the number of action potentials evoked by current injections (5-fold).

CONCLUSION

The finding that NTS neurons in a primate model of allergic asthma undergo intrinsic increases in excitability suggests that CNS mechanisms might contribute to the exaggerated symptoms in asthmatic individuals exposed to allergen.