RT Journal Article
SR Electronic
T1 YKL-40: Novel marker for pro-inflammatory M1 macrophages
JF European Respiratory Journal
JO Eur Respir J
FD European Respiratory Society
SP p3861
VO 38
IS Suppl 55
A1 Lisette Kunz
A1 Emily van 't Wout
A1 Annemarie van Schadewijk
A1 Pieter Hiemstra
YR 2011
UL http://erj.ersjournals.com/content/38/Suppl_55/p3861.abstract
AB Macrophages play a major role in the pathogenesis of COPD and comprise a heterogeneous cell population with pro- (M1) and anti-inflammatory (M2) cells. CD163 has been identified as a M2 marker, however, many M1 markers are not suitable for analysis. Cells positive for YKL-40, a chitinase-like-protein, are elevated in the lungs of smoking than non-smoking COPD patients. Dexamethasone strongly reduces YKL-40 expression in peripheral blood mononuclear cells in vitro, suggesting that inhaled steroids in COPD may decrease YKL-40 expression. We evaluated YKL-40 expression in cultured M1 and M2, and the effect of dexamethasone on its expression.Monocytes were cultured in vitro for 7 days with GM-CSF or M-CSF (for M1 and M2, resp.) and stimulated for 24h with LPS, TNFα, oncostatin M or IL-6. Dexamethasone was added in various concentrations. IL-12 and IL-10 ELISA were used to check differentiation into M1 and M2, resp. YKL-40 ELISA was performed on supernatants; quantitative PCR (qPCR) was used to analyze YKL-40 mRNA. Differences between conditions were calculated with Wilcoxon signed rank tests.M1 cells secreted more YKL-40 than M2, independent of stimulation (261ng/ml vs 65ng/ml, p=0.03). Compared to medium, LPS, TNFα, oncostatin M or IL-6 stimulation did not affect YKL-40 release in M1 and M2 (p>0.05). qPCR confirmed these results. Dexamethasone dose-dependently and strongly inhibited YKL-40 in both M1 and M2 (p<0.05).In conclusion, M1 have a higher expression of YKL-40 than M2, which is unchanged by pro-inflammatory stimuli. In addition, YKL-40 release is strongly inhibited by dexamethasone in both M1 and M2. These results indicate that YKL-40 expression can be used as a marker for M1 macrophages in vitro, and possibly in vivo.