Hydrogen Peroxide Induces Murine Macrophage Chemokine Gene Transcription Via Extracellular Signal-Regulated Kinase- and Cyclic Adenosine 5 -Monophosphate (cAMP)-Dependent Pathways: Involvement of NF- B, Activator Protein 1, and cAMP Response Element Binding Protein

Hydrogen peroxide (H2O2) has been shown to act as a second messenger that activates chemokine expression. In the present study, we investigated the mechanisms underlying this cellular regulation in the murine macrophage cell line B10R. We report that H2O2 increases mRNA expression of various chemokines, macrophage-inflammatory protein (MIP)-1 /CC chemokine ligand (CCL)3, MIP-1 /CCL4, MIP-2/CXC chemokine ligand 2, and monocyte chemoattractant protein-1/CCL2, by activating the extracellular signal-regulated kinase (ERK) pathway and the nuclear translocation of the transcription factors NFB, AP-1, and CREB. Blockage of the ERK pathway with specific inhibitors against mitogen-activated protein kinase kinase 1/2 and ERK1/ERK2 completely abolished both the H2O2-mediated chemokine up-regulation and the activation of all NF studied. Similarly, selective inhibition of cAMP and NFB strongly down-regulated the induction of all chemokine transcripts as well as CREB and NFB activation, respectively. Of interest, we detected a significant decrease of NFB, AP-1, and CREB DNA binding activities by reciprocal competition for these binding sites when either specific cold oligonucleotides (NFB, AP-1, and CREB) or Abs against various transcription factor subunits (p50, p65, c-Fos, Jun B, c-Jun, and CREB-1) were added. These findings indicate that cooperation between ERKand cAMP-dependent pathways seems to be required to achieve the formation of an essential transcriptional factor complex for maximal H2O2-dependent chemokine modulation. Finally, experiments performed with actinomycin D suggest that H2O2-mediated MIP-1 mRNA up-regulation results from transcriptional control, whereas that of MIP-1 , MIP-2, and monocyte chemoattractant protein-1 is due to both gene transcription activation and mRNA posttranscriptional stabilization. The Journal of Immunology, 2002, 169: 7026–7038.