Bites from the brown recluse spider and other Loxosceles arachnids result in dermonecrotic skin lesions. Neutrophils (PMN) are essential to the development of Loxosceles-induced skin lesions, but paradoxically, in vitro PMN activation is inhibited by direct exposure to
Loxosceles venom. Neutrophil activation occurs in response to a myriad of soluble mediators that include members of both the alpha and
beta chemokine families. Because arachnid envenomation results in the exposure of several different cell types to
venom, we investigated
venom-induced expression of alpha and
beta chemokines in both endothelial cells (human umbilical vein; HUVEC) and epithelial cells (A549 pneumocytes).
Chemokine-specific capture
enzyme immunoassays (EIA) were used to measure Loxosceles deserta
venom-induced
alpha chemokines:
interleukin-8 (IL-8), growth-related oncogene-alpha (GRO-alpha), and
beta chemokines: monocyte
chemoattractant protein-1(MCP-1), and regulated on activation, normal T cell expressed and secreted (
RANTES) in cell-free
conditioned media from HUVEC and A549 cell monolayers. Exposure of HUVECs (8 h) to Laxosceles
venom resulted in the production of
IL-8 (5.2+/-1.30 ng/ml), MCP-1 (1.44+/-0.11 ng/ml) and GRO-alpha (1.97+/-0.15 ng/ml) in a dose and time-dependent manner. Exposure of A549 cell monolayers to
venom resulted in
IL-8 (7.74+/-0.30 ng/ml), and MCP-1 (2.61+/-0.31 ng/ml), but neither GRO-alpha nor
RANTES accumulated during an 8-hour incubation period.
Chemokines accumulated in a
venom dose and time-dependent manner. Neither cell type secreted
RANTES in response to
Loxosceles venom. These data indicate that
Loxosceles spider venom is a potent inducer of alpha and
beta chemokines in both endothelial and epithelial cell types. Based on the established roles of
IL-8, MCP-1, and GRO-alpha, in
inflammation, these observations have relevance to the pathophysiology of Loxosceles-induced dermonecrosis.