Hydrogen peroxide stimulates macrophage vascular endothelial growth factor release

Neutrophils gather at the wound site shortly after trauma and release bactericidal reactive oxygen species (ROS) and H2O2 to kill bacteria and prevent infection. Macrophages arrive at the wound in response to environmental stimuli, phagocytose foreign particles, and release vascular endothelial growth factor (VEGF), an angiogenic factor crucial for wound healing. Because oxidants are released early in inflammation and have been found to regulate transcription factors, we investigated a possible role of H2O2 in VEGF stimulation. Human U937 macrophages exposed to H2O2 and allowed to recover in H2O2-free medium rapidly showed an increase in VEGF mRNA. The H2O2-mediated mRNA increase was dose dependent, blocked by catalase, and associated with elevated VEGF in conditioned media. The increase in VEGF was also found in primary rat peritoneal macrophages and the RAW 264.7 murine macrophage cell line. Transcriptional inhibition with actinomycin D revealed no significant difference in mRNA half-life. Transient transfections with a 1.6-kb VEGF promoter-luciferase construct (Shima DT, Kuroki M, Deutsch U, Ng YS, Adamis AP, and D'Amore PA. J Biol Chem 271: 3877-3883, 1996) showed a ninefold stimulation of VEGF gene promoter activity. We concluded that H2O2 increases macrophage VEGF through an oxidant induction of VEGF promoter. This oxidant stimulation can be mediated by activated neutrophils.