Darren Bayley

Relationship between airway inflammation and the frequency of exacerbations in patients with smoking related COPD

BACKGROUND Patients with more frequent exacerbations of chronic obstructive pulmonary disease (COPD) may have increased bronchial inflammation. Airway inflammation was measured in patients who had been thoroughly investigated with full pulmonary function testing, thoracic HRCT scanning, and sputum microbiology to examine further the relationship between exacerbation frequency and bronchial inflammation. METHODS Airway inflammation (spontaneous sputum sol phase myeloperoxidase (MPO), elastase, leukotriene (LT)B4, interleukin (IL)-8, secretory leukoprotenase inhibitor (SLPI), protein leakage) and serum levels of C reactive protein (CRP) were compared in 40 patients with stable, smoking related COPD, divided into those with frequent (⩾3/year) or infrequent (⩽2/year) exacerbations according to the number of primary care consultations during the preceding year. The comparisons were repeated after excluding eight otherwise clinically indistinguishable patients who had tubular bronchiectasis on the HRCT scan. RESULTS Patients with frequent (n=12) and infrequent (n=28) exacerbations were indistinguishable in terms of their clinical, pulmonary function, and sputum characteristics, CRP concentrations, and all of their bronchial inflammatory parameters (p>0.05). The patients without evidence of tubular bronchiectasis (n=32) were equally well matched but the sputum concentrations of SLPI were significantly lower in the frequent exacerbators (n=8) in this subset analysis (p<0.05). CONCLUSIONS There are several clinical features that directly influence bronchial inflammation in COPD. When these were carefully controlled for, patients with more frequent reported exacerbations had lower sputum concentrations of SLPI. This important antiproteinase is also known to possess antibacterial and antiviral activity. Further studies are required into the nature of recurrent exacerbations and, in particular, the regulation and role of SLPI in affected individuals.

Assessment of airway neutrophils by sputum colour: correlation with airways inflammation

BACKGROUND Airway inflammation, with recruitment of neutrophils to the airway lumen, results in purulent secretions and a variety of potential adverse consequences for patients with chronic bronchitis and bronchiectasis. We hypothesised that gradations of sputum colour would correlate directly with the myeloperoxidase content of sputum and with various other indicators of the activity and consequences of bronchial diseases. METHODS To test this hypothesis, we quantified sputum colour by reference to a sensitive nine point colour chart and correlated this assessment with indices of a number of inflammatory mediators in sputum. RESULTS The results indicate that standardised visual measurements of sputum colour correlated strongly with myeloperoxidase, interleukin 8, leucocyte elastase (both activity and total quantity), sputum volume, protein leak, and secretory leucocyte proteinase inhibitor (p<0.001 for all). In addition, there was a strong direct correlation between leucocyte elastase and both myeloperoxidase (p<0.003) and sputum volume (p<0.001), but a strong negative correlation with secretory leucocyte proteinase inhibitor (p<0.001). CONCLUSIONS These results indicate that sputum colour graded visually relates to the activity of the underlying markers of bronchial inflammation. The results of this simple visual analysis of sputum provides guidance concerning underlying inflammation and its damaging potential. It also provides a useful scientific tool for improving the monitoring of chronic airways diseases and response to treatment.

Behavioral and structural differences in migrating peripheral neutrophils from patients with chronic obstructive pulmonary disease.

RATIONALE There are increased neutrophils in the lungs of patients with chronic obstructive pulmonary disease (COPD), but it is unclear if this is due to increased inflammatory signal or related to the inherent behavior of the neutrophils. This is critical, because inaccurate or excessive neutrophil chemotaxis could drive pathological accumulation and tissue damage. OBJECTIVES To assess migratory dynamics of neutrophils isolated from patients with COPD compared with healthy smoking and nonsmoking control subjects and patients with α(1)-antitryspin deficiency. METHODS Migratory dynamics and structure were assessed in circulating neutrophils, using phase and differential interference contrast microscopy and time-lapse photography. The effect of COPD severity was studied. Surface expression of receptors was measured using flow cytometry. The in vitro effects of a phosphoinositide 3-kinase inhibitor (LY294002) were studied. MEASUREMENTS AND MAIN RESULTS COPD neutrophils moved with greater speed than cells from either control group but with reduced migratory accuracy, in the presence of IL-8, growth-related oncogene α, formyl-methionyl-leucyl-phenylalanine, and sputum. This was present across all stages of COPD. Structurally, COPD neutrophils formed fewer pseudopods during migration. There were no differences in surface expression of the receptors CXCR1, CXCR2, or FPR1. LY294002 reduced COPD neutrophil migratory speed while increasing chemotactic accuracy, returning values to normal. The inhibitor did not have these effects in healthy control subjects or patients with a similar degree of lung disease. CONCLUSIONS COPD neutrophils are intrinsically different than cells from other studied populations in their chemotactic behavior and migratory structure. Differences are not due to surface expression of chemoattractant receptors but instead appear to be due to differences in cell signaling.

Inflammation in sputum relates to progression of disease in subjects with COPD: a prospective descriptive study

BackgroundInflammation is considered to be of primary pathogenic importance in COPD but the evidence on which current understanding is based does not distinguish between cause and effect, and no single mechanism can account for the complex pathology. We performed a prospective longitudinal study of subjects with COPD that related markers of sputum inflammation at baseline to subsequent disease progression.MethodsA cohort of 56 patients with chronic bronchitis was characterized in the stable state at baseline and after an interval of four years, using physiological measures and CT densitometry. Sputum markers of airway inflammation were quantified at baseline from spontaneously produced sputum in a sub-group (n = 38), and inflammation severity was related to subsequent disease progression.ResultsPhysiological and CT measures indicated disease progression in the whole group. In the sub-group, sputum myeloperoxidase correlated with decline in FEV1 (rs = -0.344, p = 0.019, n = 37). LTB4 and albumin leakage correlated with TLCO decline (rs = -0.310, p = 0.033, rs = -0.401, p = 0.008, respectively, n = 35) and IL-8 correlated with progression of lung densitometric indices (rs = -0.464, p = 0.005, n = 38).ConclusionThe data support a principal causative role for neutrophilic inflammation in the pathogenesis of COPD and suggest that the measurement of sputum inflammatory markers may have a predictive role in clinical practice.

Inter-relationships between inflammatory markers in patients with stable COPD with bronchitis: intra-patient and inter-patient variability

Background: Measurements of pulmonary biomarkers can be used to monitor airway inflammation in chronic obstructive pulmonary disease (COPD), but the variability of sampled biomarkers and their inter-relationships are poorly understood. A study was undertaken to examine the intra- and inter-patient variability in spontaneous sputum samples from patients in the stable state and to describe the relationship between biomarkers, cell counts and markers of disease. Methods: Sputum interleukin-1β, tumour necrosis factor α, interleukin 8, myeloperoxidase, leucotriene B4, growth-related oncogene α and differential cell counts were measured in patients with moderate to severe stable COPD (n = 14) on 11 occasions over a 1-month period. Results: There was significant variability in all inflammatory indices (median intra-patient coefficient of variation (CV) 35% (IQR 22–69), median inter-patient CV 102% (IQR 61–145)). Variability could be reduced by using a rolling mean of individual patient data points. Sample size calculations were undertaken to determine the number of patients required to detect a 50% reduction in neutrophil count. Using a crossover design of a putative effective treatment, the number needed using one data point per patient was 72, reducing to 23 when a mean of three data points was used. Significant correlations were demonstrated both between the inflammatory biomarkers themselves and between inflammatory biomarkers and markers of disease. Some relationships were not apparent when results from a single sample were used. The reliability of inter-relationships improved as more data points were used for each patient. Conclusions: Clear relationships exist between inflammatory biomarkers in patients with stable COPD. Sequential sampling reduced the variability of individual mediators and the potential number of patients needed to power proof of concept interventional studies.

Validation of Assays for Inflammatory Mediators in Exhaled Breath Condensate

The use of exhaled breath condensate (EBC) as a tool for noninvasive assessment of lung inflammation is becoming commonplace. Many authors use commercial ELISA kits to measure inflammatory mediators within EBC. However, the very low concentrations of mediators within EBC are often below the commercially validated concentration range of the relevant ELISA and crucially below the linear part of the sigmoid standard curve. The present study seeks to validate a series of assays for use in EBC and to compare the results in EBC with those from matched sol phase sputum samples. The following mediators were measured by ELISA: leukotriene (LT)B4, interleukin (IL)-8, secretory leukoprotease inhibitor and α1-antitrypsin (AAT). Myeloperoxidase was measured by chromogenic substrate assay. Mediator concentrations reached the lower limit of quantification in only one assay (AAT) in 19.6% of subjects, while mediator concentrations reached the lower limit of detection in three assays (LTB4, IL-8 and AAT in 31, 6.5 and 61% of subjects, respectively). No significant correlations were present between any mediators in EBC and sol phase sputum. The results of the present study indicate that care must be exercised when interpreting mediator measurements in exhaled breath condensate and that assays must be validated at concentrations relevant to those found within the biological fluid.

The TNFalpha gene relates to clinical phenotype in alpha-1-antitrypsin deficiency.

BackgroundGenetic variation may underlie phenotypic variation in chronic obstructive pulmonary disease (COPD) in subjects with and without alpha 1 antitrypsin deficiency (AATD). Genotype specific sub-phenotypes are likely and may underlie the poor replication of previous genetic studies. This study investigated subjects with AATD to determine the relationship between specific phenotypes and TNFα polymorphisms.Methods424 unrelated subjects of the PiZZ genotype were assessed for history of chronic bronchitis, impairment of lung function and radiological presence of emphysema and bronchiectasis. A subset of subjects with 3 years consecutive lung function data was assessed for decline of lung function. Four single nucleotide polymorphisms (SNPs) tagging TNFα were genotyped using TaqMan® genotyping technologies and compared between subjects affected by each phenotype and those unaffected. Plasma TNFα levels were measured in all PiZZ subjects.ResultsAll SNPs were in Hardy-Weinberg equilibrium. A significant difference in rs361525 genotype (p = 0.01) and allele (p = 0.01) frequency was seen between subjects with and without chronic bronchitis, independent of the presence of other phenotypes. TNFα plasma level showed no phenotypic or genotypic associations.ConclusionVariation in TNFα is associated with chronic bronchitis in AATD.

The validation of assays used to measure biomarkers in exhaled breath condensate

To the Editors: We read with interest the article by Rosias et al. 1 in a recent issue of the European Respiratory Journal . The authors attempted to validate a number of assays using exhaled breath condensate. The values described by Rosias et al. 1 were very similar to those reported by many laboratories, but our interpretation of the data is different. Our experience in validating similar assays in this medium suggests that measuring mediators at these low concentrations is problematic and, as such, we have the following concerns with the article which other researchers need to be aware of. First, Rosias et al. 1 based coefficient of variation (CV) on a mean of spiked samples, where the spike was far in excess of the measured values. The CVs given were based upon the sample plus spike, rather than the sample alone. In the majority of assays, the working range …

Inflammatory Mediators in Spontaneously Produced Sputum

Airway inflammation is currently the subject of intense research interest concerning both the nature of the inflammatory cells, proteins, and cytokines present. These data are being used to define and assess the severity, cause, prognosis, and response to treatment of airway inflammatory disease. Spontaneous sputum is a useful method for studying inflammation in the larger airways, in diseases such as asthma, bronchitis, and bronchiectasis.