Peçonha bruta de Loxosceles similis (Moenkhaus, 1898) ativa uma via apoptótica dependente de caspases em fibroblastos dérmicos humanos

Abstract

Spiders from the Loxosceles genus represent a risk to human health due to the systemic and necrotic effect of their bite. The symptoms of envenomation with the brown spiders may vary from dermonecrosis in the majority of cases to coagulopathy and hemolysis leading to acute renal failure. Even though the systemic effects are well characterized, the cell death mechanisms triggered by the venom of the brown spiders are still not well described in literature. There is evidence in literature that many cells treated with the venom enter in an apoptotic process, however the triggering of this response is not well comprehended. In the present study we assessed the caspases activated during the process of apoptosis begun in vitro by the Loxosceles similis venom. Using the test of MTT metabolization, we verified that among all tested cell lines, only primary fibroblasts were affected by the brown spiders venom. We demonstrate using fluorescence microscopy and flow cytometry that human fibroblasts treated with the whole venom started an apoptotic response. Furthermore, using flow cytometry we verified that the inhibition of caspases-4, -6 and -9 decreased the percentage of cells labeled with the apoptosis marker annexin V-FITC. Ultimately, by fluorescence microscopy we could observe that the effectors caspases-3 and -7 are also activated during the process.