title: Platelet participation in the pathogenesis of dermonecrosis induced by Loxosceles gaucho venom.
abstract: Loxosceles gaucho spider venom induces in vitro platelet activation and marked thrombocytopenia in rabbits. Herein, we investigated the involvement of platelets in the development of the dermonecrosis induced by L. gaucho venom, using thrombocytopenic rabbits as a model. L. gaucho venom evoked a drop in platelet and neutrophil counts 4 h after venom injection. Ecchymotic areas at the site of venom inoculation were noticed as soon as 4 h in thrombocytopenic animals but not in animals with initial normal platelet counts. After 5 days, areas of scars in thrombocytopenic animals were also larger, evidencing the marked development of lesions in the condition of thrombocytopenia. Histologically, local hemorrhage, collagen fiber disorganization, and edema were more severe in thrombocytopenic animals. Leukocyte infiltration, predominantly due to polymorphonuclears, was observed in the presence or not of thrombocytopenia. Thrombus formation was demonstrated by immunohistochemistry at the microvasculature, and it occurred even under marked thrombocytopenia. Taken together, platelets have an important role in minimizing not only the hemorrhagic phenomena but also the inflammatory and wound-healing processes, suggesting that cutaneous loxoscelism may be aggravated under thrombocytopenic conditions.
authors.affiliation: Centro Universitário Dinâmica das Cataratas, Foz do Iguaçu, Paraná, Brazil Laboratório de Fisiopatologia, Instituto Butantan, São Paulo, Brazil flutavares@gmail.com.
authors.forename: F L
authors.initials: FL
authors.lastname: Tavares
authors.affiliation: Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) e Instituto Nacional de Medicina Tropical (INMeT), Puerto Iguazú, Misiones, Argentina.
authors.forename: M E
authors.initials: ME
authors.lastname: Peichoto
authors.affiliation: Divisão de Desenvolvimento Tecnológico e Produção, Instituto Butantan, São Paulo, Brazil.
authors.forename: J R
authors.initials: JR
authors.lastname: Marcelino
authors.affiliation: Laboratório de Imunopatologia, Instituto Butantan, São Paulo, Brazil.
authors.forename: K C
authors.initials: KC
authors.lastname: Barbaro
authors.affiliation: Laboratório de Fisiopatologia, Instituto Butantan, São Paulo, Brazil.
authors.forename: M C
authors.initials: MC
authors.lastname: Cirillo
authors.affiliation: Laboratório de Fisiopatologia, Instituto Butantan, São Paulo, Brazil.
authors.forename: M L
authors.initials: ML
authors.lastname: Santoro
authors.affiliation: Laboratório de Fisiopatologia, Instituto Butantan, São Paulo, Brazil.
authors.forename: I S
authors.initials: IS
authors.lastname: Sano-Martins
mesh_terms: D000818:Animals; D001772:Blood Cell Count; D001792:Blood Platelets / Q000502:physiology*; D004195:Disease Models, Animal; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000378:metabolism; D009336:Necrosis; D009504:Neutrophils / Q000187:drug effects; D010587:Phagocytosis / Q000187:drug effects; D010727:Phosphoric Diester Hydrolases / Q000633:toxicity*; D011517:Prothrombin Time; D011817:Rabbits; D012867:Skin / Q000098:blood supply / Q000187:drug effects* / Q000473:pathology; D012871:Skin Diseases / Q000097:blood* / Q000139:chemically induced / Q000473:pathology*; D013111:Spider Venoms / Q000633:toxicity*; D013921:Thrombocytopenia / Q000097:blood; D014841:von Willebrand Factor / Q000032:analysis
chemical_list: D013111:Spider Venoms; C055161:loxosceles venom; D014841:von Willebrand Factor; D010727:Phosphoric Diester Hydrolases
keywords: Loxosceles; Spider venom; dermonecrosis; platelets; thrombocytopenia