Background: Patients with chronic obstructive pulmonary disease (COPD) have increased numbers of neutrophils and macrophages in their lungs. Growth related oncogene-α (GROα) attracts neutrophils, whereas monocyte chemoattractant protein-1 (MCP-1) attracts monocytes that can differentiate into macrophages. The aim of this study was to determine the concentration of GROα and MCP-1 in bronchoalveolar lavage (BAL) fluid and sputum from non-smokers, healthy smokers and patients with COPD, and to see if there was a correlation between the concentrations of these chemokines, lung function, and numbers of inflammatory cells. Methods: BAL fluid and sputum from non-smokers (n=32), healthy smokers (n=36), and patients with COPD (n=40) were analysed for the presence of GROα and MCP-1 using ELISA. Cells counts were performed on the samples and correlations between the concentrations of these chemokines, lung function, and inflammatory cells observed. Results: Median (SE) GROα and MCP-1 levels were significantly increased in sputum from patients with COPD compared with non-smokers and healthy smokers (GROα: 31 (11) v 2 (2) v 3 (0.8) ng/ml; MCP-1: 0.8 (0.4) v 0.2 (0.1) v 0.1 (0.04) ng/ml, p<0.05), but not in BAL fluid. There were significant negative correlations between both GROα and MCP-1 levels in sputum and forced expiratory volume in 1 second (FEV 1 ) % predicted (GROα: r=-0.5, p<0.001; MCP-1: r=-0.5, p<0.001), together with significant positive correlations between GROα and MCP-1 and neutrophil numbers in sputum (GROα: r=0.6, p<0.001; MCP-1: r=0.4, p<0.01). Conclusion: These results suggest that GROα and MCP-1 are involved in the migration of inflammatory cells, thus contributing to the inflammatory load associated with COPD.

Leukocyte migration is critical to maintaining host defense, but uncontrolled cellular infiltration into tissues can lead to chronic inflammation. In the lung, such diseases include chronic obstructive pulmonary disease (COPD), a debilitating, respiratory condition characterized by progressive and largely irreversible airflow limitation for which cigarette smoking is the major risk factor. COPD is associated with an increased inflammatory cell influx including increased macrophage numbers in the airways and tissue. Alveolar macrophages develop from immigrating blood monocytes and have the capacity to cause the pathological changes associated with COPD. This study addressed the hypothesis that increased macrophage numbers in COPD are a result of increased recruitment of monocytes from the circulation. Chemotaxis assays of peripheral blood mononuclear cells (PBMC)/monocytes from nonsmokers, smokers, and COPD patients demonstrated increased chemotactic responses for cells from COPD patients when compared with controls toward growth-related oncogene (GRO)alpha and neutrophil-activating peptide (NAP)-2 but not toward monocyte chemoattractant protein, interleukin-8, or epithelial-derived NAP(ENA)-78. The enhanced chemotactic response toward GROalpha and NAP-2 was not mediated by differences in expression of their cellular receptors, CXCR1 or CXCR2. Receptor expression studies using flow cytometry indicated that in COPD, monocyte expression of CXCR2 is regulated differently from nonsmokers and smokers, which may account for the enhanced migration toward GROalpha and NAP-2. The results highlight the potential of CXCR2 antagonists as therapy for COPD and demonstrate that an enhanced PBMC/monocyte response to specific CXC chemokines in these patients may contribute to increased recruitment and activation of macrophages in the lungs.

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Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors that heterodimerize with the retinoid X receptor and then modulate at the transcriptional level the function of many target genes. Three PPARs are known: alpha, beta (sometimes called delta), and gamma. The better studied are PPARalpha and PPARgamma, which are activated by fibrates and thiazolidinediones/glitazones, respectively. It is now believed that activation of the PPARs could be associated with the prevention of heart attack and stroke in humans. Here we report, for the first time, that human platelets contain PPARbeta and that its selective activation inhibits platelet aggregation. PPARbeta is a putative receptor for prostacyclin. Prostacyclin is an important antithrombotic hormone that synergizes with nitric oxide to inhibit platelet aggregation. In the current study, we show that PPARbeta ligands similarly synergize with nitric oxide to inhibit platelet aggregation. These observations challenge our view of a nuclear receptor because PPARbeta is present and active in nonnucleated platelets. Furthermore, these data suggest that some of the antithrombotic actions of prostacyclin may be mediated via activation of PPARs. Thus, our results identify PPARbeta as a novel antiplatelet target that may mediate some of the effects of prostacyclin in blood.

Asthma and chronic obstructive pulmonary disease (COPD) are different conditions with contrasting airway inflammation and parenchymal disease patterns. A number of matrix metalloproteases (MMPs) are implicated in the pathophysiology of COPD and asthma. Different profiles of airway MMPs may, therefore, be expected in asthma and COPD. The present study compared MMP profiles in the airways of non-smokers, non-symptomatic cigarette smokers, and patients with COPD or asthma (n = 15 subjects per group). Induced sputum was assessed for MMP-1, -2, -3, -8 and -9, and tissue inhibitor of metalloproteases (TIMP)-1 by ELISA. Gelatinase activity was determined by zymography. Sputum from COPD patients contained increased levels of MMP-1, -8 and -9 compared with the other groups (2-7-fold, depending upon group). MMP-9 activity was elevated in COPD sputum by 3-12-fold above the other groups. Sputum from COPD patients had 3-fold higher levels of TIMP-1 than samples from asthmatics or controls, but was not different to smokers. FEV1 correlated negatively with MMP-1, -8, -9, MMP-9 activity and TIMP-1, whereas percent neutrophils in sputum correlated positively with MMP-1, -8, -9, TIMP-1 and MMP-9 activity. The MMP profile in COPD differs to that in asthma and cigarette smokers. This may contribute to, or be a marker of, different pathophysiologies of asthma and COPD.