paper with shorter introduction

Summary: Bacterial DNA containing unmethylated CpG motifs is emerging as an important regulator of functions of human neutrophil granulocytes (polymorphonuclear leukocytes (PMN)). These motifs are recognized by TLR-9. Recent studies indicate that peroxynitrite (ONOO
) may function as an intracellular signal for the production of IL-8, one of the key regulators of leukocyte trafficking in inflammation. In this study we investigated whether bacterial DNA (CpG-DNA) could induce ONOO
signaling in human PMN. Human whole blood, isolated PMN (purity, >95%), and high purity (>99%) PMN respond to CpG-DNA, but not to calf thymus DNA, with secretion of IL-8 and, to a lesser extent, IL-6 and TNF. Methylation of cytosines in CpG-DNA resulted in a complete loss of activity. The endosomal acidification inhibitors, bafilomycin A and chloroquine, inhibited CpG-DNA-induced cytokine release from PMN. CpG-DNA-induced IL-8 mRNA expression and release was also blocked by the NO synthase inhibitor N-nitro-L-arginine methyl ester. CpG-DNA evoked concomitant increases in intracellular superoxide and NO levels, leading to enhanced ONOO
formation and, consequently, nuclear accumulation of c-Fos and NF-B. Pharmacological inhibition of NF-B activation attenuated
75% of CpG-DNA-evoked IL-8 release. These results identify ONOO
-dependent activation of NF-B and c-Fos as an important mechanism that mediates PMN responses, including IL-8 gene expression and release, to bacterial DNA and unmethylated CpG motifs in particular. Enhanced ONOO
formation represents a mechanism by which bacterial DNA may contribute to prolongation and amplification of the inflammatory response.