Modulation of bacterial DNA-induced neutrophil cytokine production by GM-CSF

FUXMAN BASS, JUAN IGNACIO, ALVAREZ MARÍA EUGENIA, VERMEULEN, MÓNICA GEFFNER, JORGE RAÚL, SALAMONE, GABRIELA TREVANI, ANALÍA SILVINA.

Salvador de Bahía, Brasil

Congreso; Recent advances in pattern recognition; 2006

We have previously demonstrated that bacterial DNA induces human neutrophil activation by a CpG-independent mechanism. In the current study we evaluated the effect of GM-CSF on the production of IL-8, IL-1b and IL-6 by human neutrophils activated by bacterial DNA. Results indicated that human neutrophil pretreatment with rhGM-CSF (50 ng/ml ) during 30, 90 or 180 min markedly enhanced IL-8 and IL-1b production induced by E coli DNA (10, 30 and 100 µg/ml) after 3 and/or 18 h culture (p<0.05; n=4-5). Contrastingly, IL-6 production induced by E coli DNA (30 and 100 µg/ml) was markedly inhibited by GM-CSF pre-treatment (p<0.05; n=4). Additional results indicated that cytokine production profiles observed in GM-CSF-pretreated neutrophils and activated by CpG-methylated E coli DNA did not differ from those triggered by unmethylated DNA. Moreover, GM-CSF modulated cytokines production induced by either single or double stranded DNA. Previously we have reported that neutrophils cannot be activated by phosphodiester CpG-containing ODNs (P-ODNs) but are activated by phosphorothioate ODNs (S-ODNs) with or without CpG motifs. In this study, we observed that pre-treatment of neutrophils with GM-CSF enabled P-ODNs to stimulate IL-8 production and markedly enhanced that triggered by S-ODNs. Both effects were observed with ODNs containing or lacking CpG motifs. Taken together our results suggest that GM-CSF modulates neutrophil cytokine production induced by bacterial DNA irrespectively of its content of unmethylated CpG motifs.