Aili L. Lazaar

SB‐656933, a novel CXCR2 selective antagonist, inhibits ex vivo neutrophil activation and ozone‐induced airway inflammation in humans

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT Receptor antagonists that block the binding of chemokines such as CXCL8 (IL-8) are effective in animals models of neutrophil-mediated inflammation. It has been hypothesized that selective inhibition of neutrophil trafficking and activation may be a useful adjunct for the treatment of inflammatory airway diseases such as chronic obstructive pulmonary disease or cystic fibrosis. A CXCR1/2 receptor antagonist has shown activity in an ozone challenge model in humans. WHAT THIS STUDY ADDS SB-656933, a selective CXCR2 antagonist, is safe and well-tolerated at single doses and is shown to inhibit agonist (CXCL1)-mediated expression of the CD11b on peripheral blood neutrophils as well as ozone-induced airway neutrophilia in healthy subjects. AIMS To determine the safety and tolerability of a novel selective CXCR2 antagonist and assess its pharmacodynamic effects using measures of neutrophil activation and function, including CD11b expression in whole blood and ozone-induced airway inflammation in healthy subjects. METHODS Flow cytometric determination of ex vivo CXCL1-induced CD11b expression on peripheral blood neutrophils was performed following single dose oral administration of SB-656933 (dose range 2-1100 mg). A subsequent randomized study (placebo, 50 mg and 150 mg) was performed to explore the dose-response for ozone-induced airway inflammation, as measured by sputum biomarkers. RESULTS Oral administration of SB-656933 resulted in significant inhibition of CXCL1-induced CD11b expression on peripheral blood neutrophils at single doses greater than or equal to 50 mg. Maximum inhibition (70%) relative to placebo was observed following administration of SB-656933 400 mg (95% CI 60%, 77%). This was sustained up to a dose of 1100 mg. Single doses of SB-656933 reduced ozone-induced airway inflammation in a dose-dependent manner. Relative to placebo, there were 55% (95% CI 20%, 75%) and 74% (95% CI 55%, 85%) fewer neutrophils in the sputum of subjects after a single dose of 50 mg or 150 mg, respectively. There was a corresponding reduction in myeloperoxidase concentrations in the sputum supernatant of 32.8% (95% CI 9.2, 50.3) and 50.5% (95% CI 33.3, 63.3). SB-656933 was safe and well-tolerated at all doses. CONCLUSIONS SB-656933 is a CXCR2 antagonist that demonstrates dose-dependent effects on neutrophil activation and recruitment within a well-tolerated dose range. These data suggest that SB-656933 may be an effective agent in neutrophil-predominant diseases.

The inhaled phosphodiesterase 4 inhibitor GSK256066 reduces allergen challenge responses in asthma.

GSK256066 is a selective phosphodiesterase 4 inhibitor that can be given by inhalation, minimising the potential for side effects. We evaluated the effects of GSK256066 on airway responses to allergen challenge in mild asthmatics.MethodsIn a randomised, double blind, cross-over study, 24 steroid naive atopic asthmatics with both early (EAR) and late (LAR) responses to inhaled allergen received inhaled GSK256066 87.5 mcg once per day and placebo for 7 days, followed by allergen challenge. Methacholine reactivity was measured 24 h post-allergen. Plasma pharmacokinetics were measured. The primary endpoint was the effect on LAR.ResultsGSK256066 significantly reduced the LAR, attenuating the fall in minimum and weighted mean FEV1 by 26.2% (p = 0.007) and 34.3% (p = 0.005) respectively compared to placebo. GSK256066 significantly reduced the EAR, inhibiting the fall in minimum and weighted mean FEV1 by 40.9% (p = 0.014) and 57.2% (p = 0.014) respectively compared to placebo. There was no effect on pre-allergen FEV1 or methacholine reactivity post allergen. GSK256066 was well tolerated, with low systemic exposure; plasma levels were not measurable after 4 hours in the majority of subjects.ConclusionsGSK256066 demonstrated a protective effect on the EAR and LAR. This is the first inhaled PDE4 inhibitor to show therapeutic potential in asthma.Trial RegistrationThis study is registered on clinicaltrials.gov NCT00380354

Mast Cell Chymase Modifies Cell-Matrix Interactions and Inhibits Mitogen-Induced Proliferation of Human Airway Smooth Muscle Cells

The hallmarks of chronic, severe asthma include prominent airway inflammation and airway smooth muscle (ASM) hypertrophy and hyperplasia. One of the factors that contribute to the injury and repair process within the airway is activation of proteases and turnover of extracellular matrix components. Mast cells, which are present in increased numbers in the asthmatic airway, are a rich source of the neutral protease chymase, which can degrade several basement membrane components. Recent data suggest that proteases also play a critical role in regulating the expression of CD44, the primary receptor for the matrix glycosaminoglycan hyaluronan. In this study we investigated the effects of chymase treatment on human ASM cell function. We found that chymase degraded the smooth muscle cell pericellular matrix. This was accompanied by an increased release of fibronectin and soluble CD44, but not soluble ICAM-1 or soluble hyaluronan, into the conditioned medium. In addition, chymase inhibited T cell adhesion to ASM and dramatically reduced epidermal growth factor-induced smooth muscle cell proliferation. These data suggest that the local release of mast cell chymase may have profound effects on ASM cell function and airway remodeling.

Regulation of Tn5 by the right-repeat proteins: Control at the level of the transposition reaction?

The transposon Tn5 consists of inverted repeats, called IS50R and IS50L, each of which encode two proteins. We show here that the larger protein encoded on IS50R, protein 1, is absolutely required for transposition. Deletion or insertion mutants that fail to make this protein fail to promote gene movement. In addition, his protein acts in cis preferentially. We also show that the smaller protein encoded on IS50R, protein 2, is competent to inhibit transposition of a Tn5 freshly introduced into the cell on a lambda phage. In contrast, the proteins from IS50L possess neither of these two activities. By assaying expression of proteins that are hybrids between beta-galactosidase and IS50R proteins, we find that the regulation of transposition cannot be due to the inhibitor repressing synthesis of Tn5 proteins. Control experiments, in which we assay synthesis of IS50 proteins synthesized from a lambda::IS50R that has been infected into cells carrying the transposition inhibitor, confirm this conclusion.

Safety and early treatment effects of the CXCR2 antagonist SB-656933 in patients with cystic fibrosis

BACKGROUND It is hypothesized that a CXCR2 receptor antagonist would inhibit the recruitment and activation of neutrophils and other inflammatory cells into the lung in subjects with cystic fibrosis. The objective of this study was to evaluate the safety, tolerability and pharmacodynamics of SB-656933, an oral CXCR2 antagonist. METHODS 146 adult CF patients were randomized to receive either placebo or SB-656933 20mg or 50mg once daily for 28days. The primary endpoint was safety; secondary endpoints included pharmacokinetics, blood and sputum biomarkers, sputum microbiology, pulmonary function and respiratory symptoms. RESULTS SB-656933 was generally well tolerated. The most frequent adverse event was headache. Five subjects were withdrawn due to adverse events. In subjects receiving SB-656933 50mg, sputum neutrophils and elastase were reduced compared to baseline (probability of a true reduction, 0.889 and 0.882 respectively), and free DNA reduced compared to placebo (probability of a true reduction, 0.967), while blood levels of fibrinogen, CRP and CXCL8 were increased. There were no changes in lung function or respiratory symptoms. Average plasma concentrations of SB-656933 were lower than predicted based on previous studies, only breaching IC50 for ~4h at the 50mg dose. CONCLUSIONS SB-656933 was well-tolerated in adult patients with cystic fibrosis. Patients receiving a daily dose of 50mg showed trends for improvement in sputum inflammatory biomarkers despite potential blunting of effects by lower than expected plasma concentrations. Although the increase in systemic inflammatory markers requires further evaluation, CXCR2 antagonism may be a useful approach for modulating airway inflammation in patients with cystic fibrosis. Clinical trial registered with www.clinicaltrials.gov (NCT00903201).

Predictors of objective cough frequency in chronic obstructive pulmonary disease.

RATIONALE Cough is one of the principal symptoms of chronic obstructive pulmonary disease (COPD) but the potential drivers of cough are likely to be multifactorial and poorly understood. OBJECTIVES To quantify cough frequency in an unselected group of subjects with COPD and investigate the relationships between cough, reported sputum production, smoking, pulmonary function, and cellular airway inflammation. METHODS We studied 68 subjects with COPD (mean age, 65.6 ± 6.7 yr; 67.6% male; 23 smokers; 45 ex-smokers) and 24 healthy volunteers (mean age, 57.5 ± 8.9 yr; 37.5% male; 12 smokers; 12 nonsmokers). Subjects reported cough severity, cough-specific quality of life, and sputum expectoration and performed spirometry, sputum induction, cough reflex sensitivity to capsaicin, and 24-hour ambulatory cough monitoring. MEASUREMENTS AND MAIN RESULTS COPD current smokers had the highest cough rates (median, 9 coughs/h [interquartile range, 4.3-15.6 coughs/h]), almost double that of COPD ex-smokers (4.9 [2.3-8.7] coughs/h; P = 0.018) and healthy smokers (5.3 [1.2-8.3] coughs/h; P = 0.03), whereas healthy volunteers coughed the least (0.7 [0.2-1.4] coughs/h). Cough frequency was not influenced by age or sex and only weakly correlated with cough reflex sensitivity to capsaicin (log C5 r = -0.36; P = 0.004). Reported sputum production, smoking history, and current cigarette consumption strongly predicted cough frequency, explaining 45.1% variance in a general linear model (P < 0.001). In subjects producing a sputum sample, cough frequency was related to current cigarette consumption and percentage of sputum neutrophils (P = 0.002). CONCLUSIONS Ambulatory objective monitoring provides novel insights into the determinants of cough in COPD, suggesting sputum production, smoking, and airway inflammation may be more important than sensitivity of the cough reflex.

Elevated Airway Purines in COPD

BACKGROUND Adenosine and related purines have established roles in inflammation, and elevated airway concentrations are predicted in patients with COPD. However, accurate airway surface purine measurements can be confounded by stimulation of purine release during collection of typical respiratory samples. METHODS Airway samples were collected noninvasively as exhaled breath condensate (EBC) from 36 healthy nonsmokers (NS group), 28 healthy smokers (S group), and 89 subjects with COPD (29 with GOLD [Global Initiative for Chronic Obstructive Lung Disease] stage II, 29 with GOLD stage III, and 31 with GOLD stage IV) and analyzed with mass spectrometry for adenosine, adenosine monophosphate (AMP), and phenylalanine, plus urea as a dilution marker. Variable dilution of airway secretions in EBC was controlled using ratios to urea, and airway surface concentrations were calculated using EBC to serum urea-based dilution factors. RESULTS EBC adenosine to urea ratios were similar in NS (0.20 ± 0.21) and S (0.22 ± 0.20) groups but elevated in those with COPD (0.32 ± 0.30, P < .01 vs NS). Adenosine to urea ratios were highest in the most severely affected cohort (GOLD IV, 0.35 ± 0.34, P < .01 vs NS) and negatively correlated with FEV(1) (r = -0.27, P < .01). Elevated AMP to urea ratios were also observed in the COPD group (0.58 ± 0.97 COPD, 0.29 ± 0.35 NS, P < .02), but phenylalanine to urea ratios were similar in all groups. Airway surface adenosine concentrations calculated in a subset of subjects were 3.2 ± 2.7 μM in those with COPD (n = 28) relative to 1.7 ± 1.5 μM in the NS group (n = 16, P < .05). CONCLUSIONS Airway purines are present on airway surfaces at physiologically significant concentrations, are elevated in COPD, and correlate with markers of COPD severity. Purinergic signaling pathways are potential therapeutic targets in COPD, and EBC purines are potential noninvasive biomarkers.

VCAM-1 Activates Phosphatidylinositol 3-Kinase and Induces p120Cbl Phosphorylation in Human Airway Smooth Muscle Cells

VCAM-1 is a member of the Ig superfamily of receptors the expression of which is up-regulated on human airway smooth muscle (ASM) cells following stimulation with inflammatory mediators. The function of these receptors in adhesion is well known, but there is growing recognition that they also possess “outside-in” signaling functions, such as cytoskeletal reorganization, calcium mobilization, and cytokine release. The present study examined the activation of extracellular signal-regulated kinase and phosphatidylinositol 3-kinase (PI3K) in ASM cells following VCAM-1 engagement. VCAM-1 ligation activated extracellular signal-regulated kinase 2 and resulted in increased expression of cyclin D1, yet there was neither p27kip1 degradation nor an increase in smooth muscle cell DNA synthesis. VCAM-1 ligation, however, augmented the proliferative response to submitogenic concentrations of epidermal growth factor. VCAM-1 engagement also stimulated a rapid increase in PI3K activity. This was associated with phosphorylation of the adapter protein p120Cbl and an increase in Cbl-associated PI3K activity. These studies suggest that VCAM-1 is linked to multiple signaling pathways in human ASM cells and may function to augment growth factor-induced responses.

Airway smooth muscle as an immunomodulatory cell: a new target for pharmacotherapy?

Asthma is a disease characterized, in part, by reversible airflow obstruction, hyperresponsiveness and inflammation. Traditional concepts concerning airway inflammation have focused on leukocyte trafficking and on the effects of inflammatory mediators, cytokines and chemokines secreted by these cells. Airway smooth muscle, the major effector cell responsible for bronchomotor tone, has been thought of as a passive tissue that responds to neurohumoral control and inflammatory mediators. New evidence, however, suggests that airway smooth muscle may secrete cytokines and chemokines and express cell adhesion molecules that are important in modulating submucosal airway inflammation. The cellular and molecular mechanisms that regulate the immunomodulatory functions of airway smooth muscle may offer new and important therapeutic targets in treating this common lung disease.

Safety and tolerability of the inhaled phosphodiesterase 4 inhibitor GSK256066 in moderate COPD.

BACKGROUND Inhibition of phosphodiesterase 4 (PDE4) represents an approach to anti-inflammatory therapy in chronic obstructive pulmonary disease (COPD). GSK256066 is a potent and selective inhaled PDE4 inhibitor. The aim of this study was to investigate the safety and tolerability of 28 days repeat inhaled dosing with GSK256066 in moderate COPD. METHODS This was a Phase IIa, multicenter, parallel-group, double-blind, three-arm, placebo-controlled, four-week, randomized study with two doses of GSK256066 (25 μg, 87.5 μg). The primary endpoint was safety and tolerability. Secondary endpoints included changes in inflammatory markers in induced sputum and blood, lung function (spirometry, body plethysmography, impulse oscillometry), and pharmacokinetics. RESULTS 104 patients were randomized and 94 patients completed the study. The incidence and intensity of treatment-related adverse events were similar between treatment groups. The most frequent adverse event was nasopharyngitis and there were no serious adverse events in patients receiving GSK256066. The overall incidence of gastrointestinal adverse events was low in all treatment groups. There were no statistically significant changes in inflammatory markers in induced sputum and blood following treatment with GSK256066. Analysis of sputum mRNA suggested engagement of pharmacology, based on increased expression of cAMP-dependent genes including amphiregulin and CREM in subjects receiving GSK256066. There was a trend for an increase in post-bronchodilator FEV1 for both doses of GSK256066; in addition, for the 87.5 μg group, there was a mean reduction in residual volume of 0.367 L (95% confidence interval: 0.112, 0.622 L) relative to placebo. CONCLUSIONS Administration of inhaled GSK256066 was well-tolerated in patients with moderate COPD. Further studies would be required to confirm the favorable safety profile and to demonstrate clinical efficacy of this compound. (ClinicalTrials.gov identifier: NCT00549679).