European Position Paper on Rhinosinusitis and Nasal Polyps 2020.

The European Position Paper on Rhinosinusitis and Nasal Polyps 2020 is the update of similar evidence based position papers published in 2005 and 2007 and 2012. The core objective of the EPOS2020 guideline is to provide revised, up-to-date and clear evidence-based recommendations and integrated care pathways in ARS and CRS. EPOS2020 provides an update on the literature published and studies undertaken in the eight years since the EPOS2012 position paper was published and addresses areas not extensively covered in EPOS2012 such as paediatric CRS and sinus surgery. EPOS2020 also involves new stakeholders, including pharmacists and patients, and addresses new target users who have become more involved in the management and treatment of rhinosinusitis since the publication of the last EPOS document, including pharmacists, nurses, specialised care givers and indeed patients themselves, who employ increasing self-management of their condition using over the counter treatments. The document provides suggestions for future research in this area and offers updated guidance for definitions and outcome measurements in research in different settings. EPOS2020 contains chapters on definitions and classification where we have defined a large number of terms and indicated preferred terms. A new classification of CRS into primary and secondary CRS and further division into localized and diffuse disease, based on anatomic distribution is proposed. There are extensive chapters on epidemiology and predisposing factors, inflammatory mechanisms, (differential) diagnosis of facial pain, allergic rhinitis, genetics, cystic fibrosis, aspirin exacerbated respiratory disease, immunodeficiencies, allergic fungal rhinosinusitis and the relationship between upper and lower airways. The chapters on paediatric acute and chronic rhinosinusitis are totally rewritten. All available evidence for the management of acute rhinosinusitis and chronic rhinosinusitis with or without nasal polyps in adults and children is systematically reviewed and integrated care pathways based on the evidence are proposed. Despite considerable increases in the amount of quality publications in recent years, a large number of practical clinical questions remain. It was agreed that the best way to address these was to conduct a Delphi exercise . The results have been integrated into the respective sections. Last but not least, advice for patients and pharmacists and a new list of research needs are included. The full document can be downloaded for free on the website of this journal: http://www.rhinologyjournal.com.

Insights in particulate matter-induced allergic airway inflammation: Focus on the epithelium.

Outdoor air pollution is a major environmental health problem throughout the world. In particular, exposure to particulate matter (PM) has been associated with the development and exacerbation of several respiratory diseases, including asthma. Although the adverse health effects of PM have been demonstrated for many years, the underlying mechanisms have not been fully identified. In this review, we focus on the role of the lung epithelium and specifically highlight multiple cytokines in PM-induced respiratory responses. We describe the available literature on the topic including in vitro studies, findings in humans (ie observations in human cohorts, human controlled exposure and ex vivo studies) and in vivo animal studies. In brief, it has been shown that exposure to PM modulates the airway epithelium and promotes the production of several cytokines, including IL-1, IL-6, IL-8, IL-25, IL-33, TNF-α, TSLP and GM-CSF. Further, we propose that PM-induced type 2-promoting cytokines are important mediators in the acute and aggravating effects of PM on airway inflammation. Targeting these cytokines could therefore be a new approach in the treatment of asthma.

COPD is associated with reduced pulmonary interstitial expression of pentraxin-3.

Pentraxin (PTX)3 is involved in antimicrobial defence, apoptotic cell clearance and extracellular matrix stability. As these processes are altered in chronic obstructive pulmonary disease (COPD), we aimed to investigate PTX3 expression in patients with this disease. PTX3 expression was quantified by immunohistochemical staining of lung tissue from never-smokers, smokers without COPD, and in patients with COPD of Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage I, II and III-IV. mRNA expression was examined in total lung tissue by quantitative RT-PCR. PTX3 concentration was measured in induced sputum and plasma by ELISA. PTX3 is mainly localised in the interstitium of the small airways and alveolar walls. There were no significant differences in pulmonary, sputum and plasma PTX3 expression between study groups. However, PTX3 expression in small airways correlated significantly with forced expiratory volume in 1 s (r = 0.35, p = 0.004). In the alveolar walls, PTX3 expression correlated significantly with carbon monoxide transfer coefficient (r = 0.28, p = 0.04). In sputum, PTX3 levels were highly correlated with the number of neutrophils. Finally, systemic levels of PTX3 tended to be lower in severe COPD compared with mild COPD. In COPD, airflow limitation and reduced transfer coefficient for carbon monoxide are associated with lower pulmonary interstitial expression of PTX3.

Role of IL-1α and the Nlrp3/caspase-1/IL-1ß axis in cigarette smoke-induced pulmonary inflammation and COPD.

Cigarette smoke (CS), the primary risk factor of chronic obstructive pulmonary disease (COPD), leads to pulmonary inflammation through interleukin-1 receptor (IL-1R)I signalling, as determined using COPD mouse models. It is unclear whether interleukin (IL)-1α or IL-1ß, activated by the Nlrp3/caspase-1 axis, is the predominant ligand for IL-1RI in CS-induced responses. We exposed wild-type mice (treated with anti-IL-1α or anti-IL-1ß antibodies), and IL-1RI knockout (KO), Nlrp3 KO and caspase-1 KO mice to CS for 3 days or 4 weeks and evaluated pulmonary inflammation. Additionally, we measured the levels of IL-1α and IL-1ß mRNA (in total lung tissue by RT-PCR) and protein (in induced sputum by ELISA) of never-smokers, smokers without COPD and patients with COPD. In CS-exposed mice, pulmonary inflammation was dependent on IL-1RI and could be significantly attenuated by neutralising IL-1α or IL-1ß. Interestingly, CS-induced inflammation occurred independently of IL-1ß activation by the Nlrp3/caspase-1 axis. In human subjects, IL-1α and IL-1ß were significantly increased in total lung tissue and induced sputum of patients with COPD, respectively, compared with never-smokers. These results suggest that not only IL-1ß but also IL-1α should be considered as an important mediator in CS-induced inflammation and COPD.

Hedgehog-interacting protein is a COPD susceptibility gene: the Rotterdam Study.

The Hedgehog signalling pathway plays an important role in lung morphogenesis and cellular responses to lung injury. A genome-wide association study has demonstrated that two single nucleotide polymorphisms (SNPs) near the Hedgehog-interacting protein (Hip) gene, SNP identifiers rs1828591 and rs13118928, are associated with risk of chronic obstructive pulmonary disease (COPD). The aim of the present study was to validate the observed association between genetic variation near the Hip gene and COPD, and to investigate whether risk estimates were modified by smoking behaviour. The association between the Hip gene SNPs and COPD was investigated in the Rotterdam Study by logistic regression analyses, adjusted for several covariates. In addition, an association meta-analysis was performed that included data from the genome-wide association study on COPD. Both SNPs were significantly associated with risk of COPD (OR 0.80; 95% CI 0.72-0.91). Homozygosity for the minor G allele resulted in a decreased risk of COPD of approximately 40% (95% CI 0.47-0.78). There was a significant interaction with the number of pack-years of smoking (p = 0.004). The meta-analysis yielded an odds ratio for COPD of 0.80 per additional G allele (p = 3.4 x 10(-9)). Genetic variation near the Hip gene was significantly associated with risk of COPD, depending on the number of pack-years of smoking.

Plasmacytoid dendritic cells in pulmonary lymphoid follicles of patients with COPD.

Plasmacytoid dendritic cells (pDCs) are professional antigen-presenting cells with antiviral and tolerogenic capabilities. Viral infections and autoimmunity are proposed to be important mechanisms in the pathogenesis of chronic obstructive pulmonary disease (COPD). The study aimed to quantify blood dendritic cell antigen 2-positive pDCs in lungs of subjects with or without COPD by immunohistochemistry and flow cytometry, combined with the investigation of the influence of cigarette smoke extract (CSE) on the function of pDCs in vitro. pDCs were mainly located in lymphoid follicles, a finding compatible with their expression of lymphoid homing chemokine receptors CXCR3 and CXCR4. pDC accumulated in the lymphoid follicles and in lung digests of patients with mild to moderate COPD, compared with smokers without airflow limitation and patients with COPD Global Initiative for Chronic Obstructive Lung disease (GOLD) stage III-IV. Exposing maturing pDC of healthy subjects to CSE in vitro revealed an attenuation of the expression of co-stimulatory molecules and impaired interferon-α production. Maturing pDC from patients with COPD produced higher levels of tumour necrosis factor (TNF)-α and interleukin (IL)-8 compared to pDC from healthy subjects. CSE significantly impairs the antiviral function of pDCs. In COPD, a GOLD stage dependent accumulation of pDC in lymphoid follicles is present, combined with an enhanced production of TNF-α and IL-8 by maturing pDCs.

The role of miR-155 in cigarette smoke-induced pulmonary inflammation and COPD.

Chronic obstructive pulmonary disease (COPD) is a highly prevalent respiratory disease characterized by airflow limitation and chronic inflammation. MiR-155 is described as an ancient regulator of the immune system. Our objective was to establish a role for miR-155 in cigarette smoke (CS)-induced inflammation and COPD. We demonstrate increased miR-155 expression by RT-qPCR in lung tissue of smokers without airflow limitation and patients with COPD compared to never smokers and in lung tissue and alveolar macrophages of CS-exposed mice compared to air-exposed mice. In addition, we exposed wild type and miR-155 deficient mice to CS and show an attenuated inflammatory profile in the latter. Alveolar macrophages were sorted by FACS from the different experimental groups and their gene expression profile was analyzed by RNA sequencing. This analysis revealed increased expression of miR-155 targets and an attenuation of the CS-induced increase in inflammation-related genes in miR-155 deficient mice. Moreover, intranasal instillation of a specific miR-155 inhibitor attenuated the CS-induced pulmonary inflammation in mice. Finally, elastase-induced emphysema and lung functional changes were significantly attenuated in miR-155 deficient mice. In conclusion, we highlight a role for miR-155 in CS-induced inflammation and the pathogenesis of COPD, implicating miR-155 as a new therapeutic target in COPD.

Effects of ciclesonide and fluticasone on cortisol secretion in patients with persistent asthma.

We compared the systemic and clinical effects of ciclesonide (CIC) and fluticasone propionate (FP) administered, in addition to CIC 160 microg x day(-1) and salmeterol 50 microg twice daily, in 32 patients with persistent asthma using a randomised double-blind, placebo-controlled, double-dummy, five-period crossover design. All patients exhibited a provocative concentration leading to a 20% decrease in forced expiratory volume in 1 s (PC(20)) methacholine <8 mg x mL(-1) and a PC(20) adenosine <60 mg x mL(-1). Primary outcome was 24-h serum cortisol suppression after 7 days. Secondary outcomes were changes in PC(20) methacholine and adenosine after 9 days. FP 500 microg x day(-1) and 1,000 microg x day(-1) significantly suppressed cortisol secretion versus placebo by -46.2 (95% confidence interval (CI) -83.8- -8.5) nmol x L(-1) and by -76.1 (95% CI -112.9- -39.3) nmol x L(-1), respectively. Neither dose of CIC (320 nor 640 microg x day(-1)) had a significant suppressive effect (-28.2 (95% CI -65.5-9.2) nmol x L(-1) and -37.3 (95% CI -74.7-0.0) nmol x L(-1), respectively). Differences between FP 1,000 microg x day(-1) and both CIC treatments were statistically significant (CIC 320 microg x day(-1): -48.0 (95% CI -84.8- -11.1) nmol x L(-1); CIC 640 microg x day(-1): -38.8 (95% CI -75.7- -1.9) nmol x L(-1)). Compared with placebo, the increase in PC(20) adenosine after the four treatments was small, but significant. Greater improvements in PC(20) adenosine were seen with FP 500 microg x day(-1) (1.8 (95% CI 1.0-2.6) doubling concentrations) compared with CIC 320 microg x day(-1) (0.9 (95% CI 0.1-1.7) doubling concentrations). No significant difference was seen between CIC 640 microg x day(-1) and FP 1,000 microg x day(-1). For a similar decrease in hyperresponsiveness, cortisol secretion was suppressed significantly with moderate-to-high doses of fluticasone propionate, but not with ciclesonide.

Role of lymphotoxin-alpha in cigarette smoke-induced inflammation and lymphoid neogenesis.

In chronic obstructive pulmonary disease (COPD), chronic inflammation is accompanied by peribronchial lymphoid aggregates. Lymphotoxin (LT)-alpha, crucial in secondary lymphoid organogenesis, may be involved in lymphoid neogenesis. We examined cigarette smoke (CS)-induced pulmonary lymphoid neogenesis and inflammation in vivo in LTalpha knockout (LTalpha(-/-)) and wild-type (WT) mice and studied the expression of lymphoid chemokines by lung fibroblasts in vitro. T-cell numbers (in bronchoalveolar lavage fluid (BALF) and lungs) and lymphoid aggregate numbers were significantly higher in air-exposed LTalpha(-/-) mice than in WT animals, and increased upon chronic CS exposure in both genotypes. In contrast, local immunoglobulin A responses upon chronic CS exposure were attenuated in LTalpha(-/-) mice. CXC chemokine ligand (CXCL) 13 and CC chemokine ligand (CCL) 19 mRNA in total lung and CXCL13 protein level in BALF increased upon CS exposure in WT, but not in LTalpha(-/-) mice. In vitro lymphotoxin-beta receptor (LTbetaR) stimulation induced CXCL13 and CCL19 mRNA in WT lung fibroblasts. Furthermore, in vitro exposure to CS extract upregulated CXCL13 mRNA expression in WT, but not in LTbetaR(-/-), lung fibroblasts. In this murine model of COPD, CS induces pulmonary expression of lymphoid chemokines CXCL13 and CCL19 in a LTalphabeta-LTbetaR-dependent fashion. However, LTalpha is not required for CS-induced pulmonary lymphocyte accumulation and neogenesis of lymphoid aggregates.

Decreased FOXP3 protein expression in patients with asthma.

BACKGROUND: T-regulatory cells (T(reg)) are important in balancing immune responses and maintaining peripheral tolerance. Current evidence suggests that asthma is characterized by a relative deficiency in T(reg), allowing T helper 2 cells to expand. In this study, we aimed to evaluate circulating T(reg), defined by the protein FOXP3, in both control subjects and patients with stable asthma. METHODS: Peripheral blood mononuclear cells (PBMC) of control (n = 14) and asthmatic patients (n = 29) were labeled for CD4, CD25, and intracellular FOXP3 and analyzed using flow cytometry. In CD3/CD28 stimulated PBMC, the effects of dexamethasone on the transcription factors T-bet, GATA-3, FOXP3, and RORc2 and representative cytokines were studied. RESULTS: In control subjects and asthmatic patients, numbers of peripheral blood CD4(+)CD25(high) and CD4(+)CD25(high)FOXP3(+) T-cells were similar. However, FOXP3 protein expression within CD4(+)CD25(high) T-cells was significantly decreased in asthmatic patients. There was a tendency for increased FOXP3 expression within CD4(+)CD25(high) T-cells in glucocorticosteroid-treated patients when compared to steroid-naive asthmatic patients. In stimulated PBMC, dexamethasone treatment increased the anti-/proinflammatory transcription ratios of FOXP3/GATA-3, FOXP3/T-bet, and FOXP3/RORc2. CONCLUSION: Asthmatic patients have decreased FOXP3 protein expression within their CD4(+)CD25(high) T(reg). Our findings also suggest that treatment with inhaled glucocorticosteroids in asthmatics might increase this FOXP3 protein expression within the CD4(+)CD25(high) T-cell population.

Bone morphogenetic protein 6 (BMP-6) modulates lung function, pulmonary iron levels and cigarette smoke-induced inflammation.

Chronic obstructive pulmonary disease (COPD) is associated with abnormal inflammatory responses and airway wall remodeling, leading to reduced lung function. An association between the bone morphogenetic protein (BMP-6) locus and forced vital capacity has been found in a genome-wide association study. However, the role of BMP-6 in the pathogenesis of COPD remains unknown. The pulmonary expression of BMP-6 was analyzed in patients with COPD and in cigarette smoke (CS)-exposed mice. We evaluated lung function and histology in BMP-6 KO mice at baseline. We exposed BMP-6 KO mice to CS for 4 weeks and measured pulmonary inflammation and iron levels. Pulmonary mRNA levels of BMP-6 were decreased in smokers with and without COPD and in CS-exposed mice. Importantly, BMP-6 expression was lowest in severe COPD. Accordingly, protein levels of BMP-6 were decreased in patients with COPD. Lung function measurements demonstrated a decreased compliance and total lung capacity in BMP-6 KO mice, whereas lung histology was normal. Furthermore, BMP-6 KO mice displayed elevated iron levels and an aggravated CS-induced inflammatory response. These results suggest that BMP-6 is important for normal lung function and that downregulation of BMP-6-as observed in patients with COPD-contributes to pulmonary inflammation after CS exposure.

Chronic inflammation in asthma: a contest of persistence vs resolution.

Recent investigations have highlighted that endogenous anti-inflammatory mediators and immune regulating mechanisms are important for the resolution of inflammatory processes. A disruption of these mechanisms can be causally related not only to the initiation of unnecessary inflammation, but also to the persistence of several chronic inflammatory diseases. In asthma, chronic Th-2 driven eosinophilic inflammation of the airways is one of the central abnormalities. To date, elucidating the role of the different pro-inflammatory mediators involved in orchestrating the inflammatory processes in asthma has been the subject of intense research in both humans and animal models. However, the counter-regulatory mechanisms that co-determine the outcome in the contest of resolution vs persistence of the eosinophilic airway inflammation remain poorly understood. These are currently being investigated in animal models of chronic asthma. Elucidating these mechanisms is of relevance, since it can give rise to a new therapeutic approach in the treatment of chronic airway inflammation in asthmatics. This novel concept of treatment involves the stimulation of endogenous anti-inflammatory pathways, rather than solely antagonising the various pro-inflammatory mediators. Here, we review and discuss the current knowledge about these endogenous anti-inflammatory mediators in clinical and experimental asthma.

Elevated GDF-15 contributes to pulmonary inflammation upon cigarette smoke exposure.

The molecular mechanisms underlying the pathogenesis of chronic obstructive pulmonary disease (COPD) are still unclear, however signaling pathways associated with lung development, such as the transforming growth factor (TGF)-ß superfamily, could be implicated in COPD. Growth differentiation factor (GDF)-15, a member of the TGF-ß superfamily, is involved in inflammation, mucus secretion, and cachexia. We analyzed the pulmonary expression of GDF-15 in smokers and patients with COPD, in cigarette smoke (CS)-exposed cultures of primary human bronchial epithelial cells (pHBECs), and in CS-exposed mice. Next, we exposed GDF-15 KO and control mice to air or CS and evaluated pulmonary inflammation. GDF-15 levels were higher in sputum supernatant and lung tissue of patients with COPD and smokers without COPD compared with never smokers. Immunohistochemistry revealed GDF-15 staining in the airway epithelium. Increased expression and secretion of GDF-15 was confirmed in vitro in CS-exposed pHBECs compared with air-exposed pHBECs. Similarly, GDF-15 levels were increased in lungs of CS-exposed mice. Importantly, GDF-15 deficiency attenuated the CS-induced pulmonary inflammation. These results suggest that increased GDF-15-as observed in lungs of smokers and patients with COPD-contributes to CS-induced pulmonary inflammation.

Tachykinin receptor antagonists: potential in airways diseases.

Several lines of evidence indicate a role for the tachykinin peptides in airways diseases. For instance, elevated levels of tachykinins have been recovered from the airways of patients with asthma and chronic obstructive pulmonary disease (COPD), and airway inflammation leads to an upregulation of the tachykinin NK1 and NK2 receptors. Recent advances in tachykinin receptor pharmacology have allowed a more detailed analysis of this system and preclinical animal studies have indicated a role for the NK1 and NK2 receptors in bronchoconstriction, airway hyperresponsiveness and airway inflammation caused by allergic and nonallergic stimuli. In the past three years, work has entered the clinic and selective or dual-selective NK1/NK2 receptor antagonists appear to have the potential to affect the different aspects of asthma and COPD.

[Indirect bronchial provocation tests: a new, specific group of bronchial provocation tests for asthma]. / Indirecte bronchiale provocatietests: een nieuwe, specifieke groep van bronchiale provocatietests voor astma.

Asthma is characterized by a variable airway obstruction, bronchial hyperresponsiveness and airway inflammation. Usually, bronchial hyperresponsiveness is measured in the clinic by provocation with non specific stimuli such as histamine or methacholine. These stimuli are called direct, as they constrict the airways by a direct stimulation of airway smooth muscle. Pharmacological stimuli such as adenosine, tachykinins and bradykinin, and physical stimuli such as exercise, isocapnic hyperventilation or hypertonic saline, are called indirect stimuli: they stimulate inflammatory cells and/or neuronal cells and the released mediator and/or neurotransmitter causes the airways to narrow. In the past 10 years the mechanisms and receptors involved in the airway narrowing caused by these indirect bronchial challenges have been characterized. It has become clear that indirect challenges form a specific group of challenges that play a role in the diagnosis and the monitoring of asthma.

Modulation by 5-HT1A receptors of the 5-HT2 receptor-mediated tachykinin-induced contraction of the rat trachea in vitro.

1. In the Fisher 344 rat, tachykinins have been shown to cause the release of 5-hydroxytryptamine (5-HT) from airway mast cells, which then causes direct smooth muscle activation as well as the release of acetylcholine from cholinergic nerves. The aim of the present study was to examine the modulatory effects of 5-HT receptors on the neurokinin A (NKA)-induced release of endogenous 5-HT and airway smooth muscle contraction in the isolated Fisher 344 rat trachea. 2. The selective 5-HT2 receptor antagonist ketanserin (0.1 microM) produced an almost complete inhibition of the contractions caused by NKA (n=4, P<0.0001, two-way ANOVA), and a significant rightward shift of the concentration-response curve to 5-HT (n=8, P<0.001, two-way ANOVA). 3. The partial agonist for 5-HT1A receptors, 8-OH-DPAT (1 microM), and the full agonist for 5-HT1 receptors, 5-CT (0.3 microM), potentiated the submaximal contractions induced by the 5-HT2 receptor agonist alpha-methyl-5-HT (0.1 microM) (n=4; P<0.005 and P<0.05, respectively). 8-OH-DPAT (1 microM), as well as the 5-HT1A receptor antagonists pMPPI, SDZ 216525 and NAN-190 (0.1 microM each), caused significant inhibition of the tracheal contractions induced both by NKA (10 nM-3 microM) and 5-HT (10 nM-10 microM) (n=4-10). This suggests that activation of 5-HT1A receptors potentiates the 5-HT2 receptor-mediated contractions. 4. SDZ 216525 (0.1 microM) significantly reduced the maximal contraction produced by 1 microM NKA (n=10, P< 0.001), without affecting the release of endogenous 5-HT. These data rule out the involvement of a 5-HT1A receptor-mediated positive feedback mechanism of the 5-HT release from mast cells. 5. Even in the presence of atropine (1 microM), 8-OH-DPAT (1 microM) further reduced the maximal NKA-induced contraction (n=4, P<0.0001), while the contractions of the rat isolated trachea induced by electrical field stimulation and the concentration-response curve to carbachol were unaffected by pMPPI (0.1 microM), SDZ 216525 (0.1 microM), NAN-190 (0.1 microM) and 8-OH-DPAT (1 microM) (n=4-6). These data demonstrate that the 5-HT1A receptor-mediated potentiation of contractile responses is not due to nonspecific inhibition of airway smooth muscle contraction or to modulation of postganglionic nerve activation. 6. The selective 5-HT1B/1D receptor antagonist GR 127935, the selective 5-HT3 receptor antagonist tropisetron and the selective 5-HT4 receptor antagonists SB 204070 and GR 113808 (0.1 microM each) had no effect on the concentration-response curve for NKA (n=6-10), ruling out the involvement of 5-HT1B/1D, 5-HT3 and 5-HT4 receptors. 7. The alpha-adrenoreceptor antagonist phentolamine (1 microM) had no effect on the 5-HT-induced contractions (n=4), ruling out the involvement of alpha-adrenoreceptors. 8. In conclusion, the tachykinin-induced contraction of the F334 rat isolated trachea is mediated by the stimulation of 5-HT2 receptors. Activation of 5-HT1A receptors located on airway smooth muscle potentiates the direct contractile effects of 5-HT2 receptor activation. The 5-HT1B/1D, 5-HT3 and 5-HT4 receptors are not involved in the NKA-induced contraction of rat airways.

Effect of nedocromil sodium on the bronchoconstrictor effect of neurokinin A in asthmatics.

In a double-blind, crossover study we have investigated the effect of nedocromil sodium on neurokinin A (NKA)-induced bronchoconstriction in asthmatics. 12 patients with mild asthma inhaled either nedocromil sodium 4mg or placebo, on 2 separate days, as 2 puffs from a metered-dose aerosol 30 minutes before challenge with NKA. On the placebo treatment day, NKA produced a concentration-dependent decrease in basal specific airway conductance (sGaw) and forced expiratory volume in 1 second (FEV1). The inhalation of nedocromil sodium 4mg inhibited the decrease in both sGaw and FEV1. The maximal percentage decrease in sGaw on the nedocromil sodium day was 27.0 +/- 5.2 (vs placebo, 53.3 +/- 5.4; p less than 0.05) and the maximal percentage decrease in FEV1 5.5 +/- 1.4 (vs placebo, 12.4 +/- 2.3; p less than 0.05). We conclude that nedocromil sodium protects against NKA-induced bronchoconstriction in asthmatics.