Loxosceles deserta spider venom induces NF-kappa B-dependent chemokine production by endothelial cells

Background: Loxosceles spider evenomation in man frequently results in disf iguring necrotic skin lesions. Recent studies suggest that several proinfla mmatory mediators participate in lesion development, We have observed that Loxosceles deserta venom induces production of the chemokines interleukin-8 , growth-related oncogene alpha, and monocyte chemoattractant protein-1 by human umbilical vein endothelial cells. Members of the Rel/Nuclear factor ( NF)-kappa B family of transcription factors are important regulators of man y genes involved in immune and inflammatory responses. We hypothesized that Loxosceles-venom-induced chemokine expression in human umbilical vein endo thelial cells is mediated by NF-kappa B, Methods: Human umbilical vein endo thelial cell monolayers were exposed to activating concentrations of Loxosc eles deserta venom. Nuclear extracts of these monolayers were analyzed by e lectrophoretic mobility shift assay. A direct cause and effect linkage betw een NF-kappa B activation and chemokine expression by Loxosceles venom was established through examination of the effect of SN50 on interleukin-8 and monocyte chemoattractant protein-1 production using a whole-cell enzyme imm unoassay, SN50 is a cell-permeable peptide that specifically blocks cytosol ic to nuclear translocation of NF-kappa B, Furthermore, the venom-induced s ynthesis of chemokine mRNAs was investigated by RNase protection assays. Re sults: Loxosceles deserta venom induces the activation of NF-kappa B in hum an umbilical vein endothelial cells. Antibodies to p50 and p65, but not to p52, c-Rel, or Rel B, induce supershifts of the DNA-protein complexes forme d by oligonucleotide probes and nuclear extracts from venom-activated human umbilical vein endothelial cells. SN50 peptide inhibits NF-kappa B translo cation and interleukin-8 and monocyte chemoattractant protein-1 production in activated human umbilical vein endothelial cells. Conclusions: Loxoscele s deserta venom induces synthesis of interleukin-8 and monocyte chemoattrac tant protein-1 mRNAs in human umbilical vein endothelial cells. The express ion of chemokines occurs via an NF-kappa B-dependent pathway.