Chemokine release by neutrophils in chronic obstructive pulmonary disease

Neutrophils are among the first cells to arrive at the site of injury. Chemokines secreted by neutrophils affect the migration of both neutrophils and other inflammatory cells, such as monocytes. It has been reported that LPS-induced release of IL-8 (CXCL-8) by neutrophils is amplified by neutrophil-derived TNF-alpha. We hypothesize that chemokine release by neutrophils is altered in chronic obstructive pulmonary disease (COPD) compared with healthy controls and that TNF-alpha may be involved in this alteration. Peripheral blood neutrophils isolated from smokers with COPD (n = 12), smokers without COPD (n = 12) and healthy, non-smokers (n = 12) were stimulated with LPS, TNF-alpha or organic dust. Anti-TNF-alpha Ab (infliximab) was used to study the effect of neutrophil-derived TNF-alpha. Release of CXCL-8, macrophage inflammatory protein-1 alpha (MIP-1 alpha, CCL-3), monocyte chemotactic protein-1 (MCP-1, CCL-2) and TNF-alpha was measured. Neutrophils spontaneously released CXCL-8, CCL-2 and CCL-3. Inhibition of TNF-alpha reduced the spontaneous release of CXCL-8 and CCL-3. Stimulation with LPS and organic dust increased the release of CXCL-8 and CCL-3 (but not CCL-2) which was reduced by inhibition of TNF-alpha. In the COPD group, inhibition of TNF-alpha failed to inhibit the release of LPS-induced CXCL-8. The role of neutrophils as cytokine and chemokine producers was confirmed. Neutrophil-derived TNF-alpha contributed to the release of chemokines after stimulation with LPS and organic dust, as the response was inhibited by infliximab. In the COPD group, infliximab did not significantly inhibit the release of CXCL-8, suggesting that the role of TNF-alpha is altered in COPD.