Inflammatory mediators generated at the site of inoculation of Loxosceles gaucho spider venom

Patients bitten by Loxosceles spiders generally manifest marked local inflammatory reaction and dermonecrosis. This report evaluated edema formation, leukocyte infiltration and release of inflammatory mediators at the injection site of Loxosceles gaucho venom. BALB/c mice were i.d. injected with venom and thereafter paws were disrupted and homogenized to obtain differential counts of migrated cells, as well to assay the levels of cytokines, chemokines and lipid mediators. Increased footpad thickness was detected as soon as 30 min after venom injection, and 24 h later was similar to that of the control group. Loxosceles venom mildly augmented the recruitment of leukocytes to the footpad in comparison with PBS-injected mice. Moreover, it stimulated the release of IL-6, MCP-1 and KC at 2 and 24 h after venom injection. In addition, higher levels of PGE₂ were detected 30 min after venom injection in comparison with control group. However, the venom failed to increase levels of IL-1β, TNF-α, TXB₂ and LTB₄. Our results demonstrate that L. gaucho venom evokes an early complex inflammatory reaction, stimulating the secretion of pro-inflammatory cytokines and lipid mediators (PGE₂), and recruiting leukocytes to the footpad which contribute to the local reaction induced by L. gaucho venom.