Reduced intracellular oxygen radical production in whole blood leukocytes from COPD patients and asymptomatic smokers

Functional Activity of Blood Neutrophils in Patients with Stable Course and Exacerbation of Chronic Obstructive Pulmonary Disease

We performed a comparative study of the parameters of chemiluminescence of blood neutrophils in patients with different severity of chronic obstructive pulmonary disease in its different periods. The maximum values of induced and spontaneous chemiluminescence were recorded at moderate severity of the disease during exacerbation. Low levels of chemiluminescence indicators were found in severe chronic obstructive pulmonary disease in the stable phase. The values of the induction period of the chemiluminescent response in patients with moderate chronic obstructive pulmonary disease were higher than in the control group. Correlations between the values of induced chemiluminescence of neutrophils and the respiration function parameter FEV1 were established, which may indicate the influence of multidirectional changes in the functional activity of systemic neutrophils on the development and worsening of airway obstruction in chronic obstructive pulmonary disease patients.

Impaired Blood Neutrophil Function in the Frequent Exacerbator of Chronic Obstructive Pulmonary Disease: A Proof-of-Concept Study

PURPOSE

The underlying biological mechanisms of the frequent exacerbator phenotype of COPD remain unclear. We compared systemic neutrophil function in COPD patients with or without frequent exacerbations.

METHODS

Whole blood from COPD frequent exacerbators (defined as ≥2 moderate-severe exacerbations in the previous 2 years) and non-exacerbators (no exacerbations in the preceding 2 years) was assayed for neutrophil function. Neutrophil function in healthy ex-smoking volunteers was also measured as a control (reference) group.

RESULTS

A total of 52 subjects were included in this study: 26 frequent exacerbators, 18 non-exacerbators and 8 healthy controls. COPD frequent exacerbators had blunted blood neutrophil fMLP-stimulated oxidative burst compared to both non-exacerbators (p < 0.01) and healthy controls (p < 0.001). There were no differences between COPD frequent exacerbators and non-exacerbators in blood neutrophil PMA-stimulated oxidative burst, but both COPD groups had reduced responses compared to healthy controls (p < 0.001). Bacterial-stimulated neutrophil degranulation was greater in frequent exacerbators than non-exacerbators (p < 0.05).

CONCLUSION

This study is the first to report aberrant receptor-mediated blood neutrophil function in the frequent exacerbator of COPD.

Neutrophil adhesion molecules in experimental rhinovirus infection in COPD

BACKGROUND

COPD exacerbations are associated with neutrophilic airway inflammation. Adhesion molecules on the surface of neutrophils may play a key role in their movement from blood to the airways. We analysed adhesion molecule expression on blood and sputum neutrophils from COPD subjects and non-obstructed smokers during experimental rhinovirus infections.

METHODS

Blood and sputum were collected from 9 COPD subjects and 10 smoking and age-matched control subjects at baseline, and neutrophil expression of the adhesion molecules and activation markers measured using flow cytometry. The markers examined were CD62L and CD162 (mediating initial steps of neutrophil rolling and capture), CD11a and CD11b (required for firm neutrophil adhesion), CD31 and CD54 (involved in neutrophil transmigration through the endothelial monolayer) and CD63 and CD66b (neutrophil activation markers). Subjects were then experimentally infected with rhinovirus-16 and repeat samples collected for neutrophil analysis at post-infection time points.

RESULTS

At baseline there were no differences in adhesion molecule expression between the COPD and non-COPD subjects. Expression of CD11a, CD31, CD62L and CD162 was reduced on sputum neutrophils compared to blood neutrophils. Following rhinovirus infection expression of CD11a expression on blood neutrophils was significantly reduced in both subject groups. CD11b, CD62L and CD162 expression was significantly reduced only in the COPD subjects. Blood neutrophil CD11b expression correlated inversely with inflammatory markers and symptom scores in COPD subjects.

CONCLUSION

Following rhinovirus infection neutrophils with higher surface expression of adhesion molecules are likely preferentially recruited to the lungs. CD11b may be a key molecule involved in neutrophil trafficking in COPD exacerbations.

Chronic obstructive pulmonary disease patients have greater systemic responsiveness to ex vivo stimulation with swine dust extract and its components versus healthy volunteers

Chronic obstructive pulmonary disease (COPD) is characterized by an airway and systemic inflammatory response. Bioaerosols/organic dusts are important agricultural pollutants that may lead to COPD. These environments are complex, containing a rich source of various microbial components. The objective of this study was to determine whether individuals with COPD have enhanced systemic responsiveness to settled swine facility organic dust extract (ODE) or its main pathogenic components (peptidoglycan [PGN], lipopolysaccharide [LPS]) versus healthy volunteers. A modified whole blood assay (WBA) that included occupational levels of ODE and concentrations of LPS and PGN found in ODE was used to determine systemic responsiveness (mediator release), and sputum inflammatory markers were measured to explore for systemic and airway associations. Sputum samples were evaluated for cell counts, and tumor necrosis factor (TNF)-α, interleukin (IL)-8/CXCL8, IL-6, and IL-10. Ex vivo whole blood stimulation with ODE, LPS, and PGN each resulted in significant mediator release in all subjects, with the highest occurring with ODE; PGN resulted in significantly enhanced TNF-α and IL-8 as compared to LPS. COPD subjects demonstrated greater systemic responsiveness using the modified WBA versus healthy controls. Within COPD subjects, blood baseline TNF-α, IL-8, and IL-10 and ODE-, PGN-, and LPS-stimulated IL-8 levels significantly correlated with lung function. In conclusion, dust-induced mediator release was robust, and PGN, in part, resembled dust-induced mediator release. Subjects with COPD demonstrated increased mediator release following ex vivo whole blood stimulation with bioaerosol components, suggesting that circulating blood cells in COPD subjects may be primed to respond greater to microbial/inflammatory insult.

Oxidative burst assessment and neutrophil-platelet complexes in unlysed whole blood

BACKGROUND

Methods currently employed for measuring reactive oxygen species production can lead to both cellular depletion and in artifactual activation. The objective of this study was to design a methodology allowing the measurement of oxidative burst (OB) with minimal sample manipulation.

METHODS

To that purpose a flow cytometry technique developed in our laboratory, based on nucleic acid staining to discriminate erythrocytes and debris, was employed. DRAQ5 dye and PECy5-CD45 monoclonal antibody (MoAb) were simultaneously used in FL3 to identify the leukocyte population and the PE-CD14 MoAb emission was detected in FL2 for monocytes. OB was measured by using the fluorogenic probe dihydrorhodamine 123, a marker of hydrogen peroxide production. Phorbol myristate acetate (PMA), Opsonized Zymosan (OZ), fMLP and calcium ionophore A23187 activators were also used in this study. For OB assays, dose-response curves were performed for each activator. In addition, the effect of activator concentration on annexin V binding, as a measure of phosphatidylserine translocation, was evaluated.

RESULTS

With this method no-lysis and no-wash steps are required, thus avoiding an unwanted damage to leukocytes. PMA and Zymosan produced an increase in annexin V binding, while fMLP and calcium ionophore did not.

CONCLUSIONS

This study reports a feasible and reproducible new flow cytometry assay for assessing OB of neutrophils and monocytes with minimal sample manipulation. In addition, under PMA and OZ conditions, the number of neutrophils showing annexin V binding was strikingly increased. This effect is not related with a phagocytic overstimulation, but with an increased neutrophil-platelet complexes formation.

Newly recruited human monocytes have a preserved responsiveness towards bacterial peptides in terms of CD11b up-regulation and intracellular hydrogen peroxide production

The transmigration of peripheral human monocytes to the interstitium is a fundamental step in the host-defence mechanism against infections. Little is known about the state of function of in vivo transmigrated interstitial monocytes prior to differentiation into macrophages and dendritic cells. We hypothesized that newly recruited interstitial monocytes have a preserved responsiveness against bacterial-related peptides, giving them a specific role in the immediate defence against invading pathogens. In order to test this hypothesis, we explored the responsiveness of in vivo transmigrated as well as peripheral monocytes, in terms of CD11b expression and H(2)O(2) production towards the bacterial-related peptide formylmethionylleucylphenylalanine (fMLP) by the use of a skin chamber technique. In addition, we analysed the concentration of interleukin (IL)-8, monocyte chemotactic protein-1 (MCP-1) and tumour necrosis factor (TNF)-alpha in the skin blister exudates and in the circulation. We demonstrate that in vivo-transmigrated monocytes had a fivefold higher CD11b expression compared to monocytes obtained from the peripheral circulation. fMLP exposure induced a significantly higher CD11b expression on transmigrated cells compared to peripheral monocytes. In addition, newly recruited monocytes had a preserved H(2)O(2) production. The interstitial concentration of IL-8, MCP-1 and TNF-alpha was significantly higher in blister exudates compared to that in the peripheral circulation. Thus, in vivo transmigrated human monocytes preserve their capacity to respond towards bacterial peptides in terms of CD11b up-regulation and H(2)O(2) generation. These data strengthen a role for newly recruited interstitial human monocytes in the immediate defence against invading pathogens.