Elevated CCL2 responses in COPD and attenuation by selective chemokine receptor antagonists

Monocyte (M¤) recruitment into the lungs of COPD can drive excessive macrophage inflammation. Increased CCL2 in sputum and BALF in COPD may drive this response; novel therapies that attenuate M¤ migration would be beneficial. The effect of CCL2 stimulation was investigated on PBMC and M¤ by measuring chemotaxis, [Ca²⁺]_i signalling and activation by up-regulation of CD11b and the effect of receptor antagonists on these responses. Chemotaxis was measured using Boyden chamber, CD11b expression was measured in whole blood by flow cytometry and [Ca2+]_i release fluorimetrically with cells from non-smokers (NS), smokers (S) and COPD. Basal CD11b did not differ in M¤ however, CCL2 (10nM) increased CD11b expression in COPD M¤ compared with S (232.1±24.1(n=5) vs 148.1±11.5(n=5 % change MFI respectively p<0.05). There was increased COPD M¤ chemotaxis to CCL2 (3nM)(COPD:67.7±7.5 n=4, NS:48.5±7.9 n=6, S:53.5±4.5 n=5 cells/field). In contrast, [Ca²⁺]_i was similar across groups (EC₅₀ NS:1.9±0.5 n=5, S:1.4±0.2 n=4 COPD:1.4±0.5 n=3 x10^-8M). These effects were inhibited by the CCR2 antagonist, PF0413, (EC₅₀ NS:3.0±1.4 n=6, S:7.3±6.8 n=6, COPD:5.1±3.7 n=5 x10^-8M) and the dual CCR2/5 antagonist, PF04173 (EC₅₀ NS:2.8±1.4 n=6, S:4.0±1.6 n=6 COPD:1.6±0.6 n=6 x10^-8M). In contrast, a CCR1 (CP4817) and CCR5 (UK4278) antagonist had no effect against CCL2 induced [Ca²⁺]_i. CCL2 highly activated COPD M¤ and is associated with increased migration, however this is not coupled with increased [Ca²⁺]_i. This response is mediated by CCR2 and can be abrogated by selective receptor antagonists. These data suggest that blocking CCR2 may be a potential anti-inflammatory therapy to prevent macrophage accumulation in COPD.