RESUMO
Loxoscelism is the pathological condition triggered by a brown spider bite. The venom of these spiders is rich in phospholipases D (PLDs), which can induce virtually all local and systemic manifestations. Recombinant mutated PLDs from clinically relevant Loxosceles species in South America have been investigated as potential antigens to develop novel therapeutic strategies for loxoscelism. However, certain gaps need to be addressed before a clinical approach can be implemented. In this study, we examined the potential of these recombinant mutated PLDs as antigens by testing some variations in the immunization scheme. Furthermore, we evaluated the efficacy of the produced antibodies in neutralizing the nephrotoxicity and sphingomyelinase activity of brown spider venoms. Our findings indicate that the number of immunizations has a greater impact on the effectiveness of neutralization compared to the amount of antigen. Specifically, two or three doses were equally effective in reducing dermonecrosis and edema. Additionally, three immunizations proved to be more effective in neutralizing mice lethality than one or two. Moreover, immunizations mitigated the signs of kidney injury, a crucial aspect given that acute renal failure is a serious systemic complication. In vitro inhibition of the sphingomyelinase activity of Loxosceles venoms, a key factor in vivo toxicity, was nearly complete after incubation with antibodies raised against these antigens. These findings underscore the importance of implementing an effective immunization scheme with multiple immunizations, without the need for high antigen doses, and enhances the spectrum of neutralization exhibited by antibodies generated with these antigens. In summary, these results highlight the strong potential of these antigens for the development of new therapeutic strategies against cutaneous and systemic manifestations of loxoscelism.
Assuntos
Fosfolipase D , Proteínas Recombinantes , Venenos de Aranha , Animais , Fosfolipase D/imunologia , Fosfolipase D/genética , Venenos de Aranha/imunologia , Camundongos , Proteínas Recombinantes/imunologia , Proteínas Recombinantes/genética , Picada de Aranha/imunologia , Aranha Marrom Reclusa/imunologia , Feminino , Antígenos/imunologia , Esfingomielina Fosfodiesterase/genética , Esfingomielina Fosfodiesterase/imunologia , Anticorpos Neutralizantes , Antivenenos/imunologia , Antivenenos/administração & dosagem , Modelos Animais de Doenças , Imunização , Diester Fosfórico HidrolasesRESUMO
BACKGROUND: Loxoscelism is a toxic clinical condition caused by the bite of spiders of the genus Loxosceles, with wide distribution throughout the world.1 Phospholipase D is responsible for dermonecrosis, inflammation, platelet aggregation, hemolysis, alteration of vascular permeability, cytotoxicity, nephrotoxicity, acute renal failure, among other symptoms involved with this protein. CASE REPORT: 27-year-old male patient, who began with a sudden episode of intense pain in the right hand, in the metacarpus and metacarpophalangeal joints. On clinical examination, the upper extremity was noted to have increased volume, extensive edema, hyperemia, and increased local temperature; The lesion progressed to extensive necrosis. Fasciotomies were performed, from distal to proximal, and release of the second and third finger compartment through longitudinal radial and ulnar incisions. A skin autograft was placed, obtained from the anterior surface of the right thigh. Opioid analgesics, non-steroidal anti-inflammatory drugs, corticosteroids, and antibiotics were administered. The skin biopsy reported: inflammatory infiltrate with neutrophils, ulceration, and bacterial colonies. After 27 days he had a favorable evolution, so he was discharged to his home, with follow-up by staff from the Outpatient Service. CONCLUSION: Cutaneous loxoscelism, as a cause of acute compartment syndrome of the hand, is rare, but should be considered in an area endemic for Loxosceles spp. Surgical decompression of the affected compartments represents a decisive factor in the treatment of patients.
ANTECEDENTES: El loxoscelismo es un cuadro clínico tóxico provocado por la mordedura de arañas del género Loxosceles, con amplia distribución en todo el mundo.1 La fosfolipasa D es la responsable de la dermonecrosis, inflamación, agregación plaquetaria, hemólisis, alteración de la permeabilidad vascular, citotoxicidad, nefrotoxicidad, insuficiencia renal aguda, entre otros síntomas implicados con esta proteína. REPORTE DE CASO: Paciente masculino de 27 años, que inició con un cuadro repentino de dolor intenso en la mano derecha, en el metacarpo y las articulaciones metacarpofalángicas. Al examen clínico, la extremidad superior se percibió con aumento de volumen, edema extenso, hiperemia y aumento de la temperatura local; la lesión progresó a necrosis extensa. Se realizaron fasciotomías, de distal a proximal, y liberación del compartimento del segundo y tercer dedo a través de incisiones longitudinales radiales y cubitales. Se colocó un autoinjerto de piel, obtenido de la superficie anterior del muslo derecho. Se administraron analgésicos opioides, antiinflamatorios no esteroides, corticosteroides y antibióticos. La biopsia de piel reporto: infiltrado inflamatorio con neutrófilos, ulceración y colonias bacterianas. Luego de 27 días tuvo evolución favorable, por lo que se dio alta a su domicilio, con seguimiento por personal del servicio de Consulta externa. CONCLUSIÓN: El loxoscelismo cutáneo, como causa de síndrome compartimental agudo de la mano, es poco común, pero debe considerarse en un área endémica para Loxosceles spp. La descompresión quirúrgica de los compartimentos afectados representa un factor decisivo en el tratamiento de los pacientes.
Assuntos
Picada de Aranha , Humanos , Masculino , Adulto , Picada de Aranha/complicações , Doença Aguda , Síndromes Compartimentais/etiologiaRESUMO
Antivenom production against Loxosceles venom relies on horses being immunized and bled for plasma harvest. One horse can partake in several cycles of antivenom production, which will require years of constant venom and adjuvant inoculation and bleeding. The actual impact on the health of horses that participate in several antivenom-producing cycles is unknown. Therefore, this study aimed to evaluate the general health status of horses that underwent at least six cycles of loxoscelic antivenom production. Seven crossbred horses that had partaken in six to eight complete antivenom-producing cycles were used and established as the immunized group (IG). Under the same handling and general management, eleven horses were established as the control group (CG). The horses were evaluated regarding their general clinical status and had their blood sampled, and an ECG recorded. The IG presented lower RBC and PCV, despite keeping values within inferior limits for the species. Renal function was not impaired, and liver-related enzymes were higher than those in the CG, probably due to liver exertion from immunoglobulin synthesis. ECG showed some abnormalities in the IG, such as atrioventricular block and a wandering atrial pacemaker, corroborated by an increase in CK-MB. The cardiovascular abnormalities were mainly found in the horses that participated in several antivenom-producing cycles. The overall results indicate that these horses had some impairment of their general health status. Once available, some alternative, less toxic antigens should replace the venom for immunization of horses used for antivenom production.
Assuntos
Antivenenos , Imunização , Cavalos , Animais , Adjuvantes Imunológicos , Antígenos , Nível de SaúdeRESUMO
Loxosceles spider envenomation results in dermonecrosis, principally due to phospholipases D (PLDs) present in the venom. These enzymes have a strongly conserved sequence, 273ATXXDNPW280, in the C-terminal region (SMD-tail) that make contact with ß-sheets of the TIM barrel, in which the amino acids Asp277 and Trp280 establish the energetically strongest contacts. The SMD-tail is conserved in PLDs from different species but absent in the non-toxic PLD ancestral glycerophosphodiester phosphodiesterases (GDPDs). This work aims to understand the role of the C-terminal region in the structural stability and/or function of phospholipases D. Through site-directed mutagenesis of the rLiD1 protein (recombinant Loxosceles intermedia dermonecrotic protein 1), we produced two mutants: rLiD1D277A and rLiD1W280A (both with sphingomyelinase activity), in which Asp277 and Trp280 were replaced by alanine. rLiD1D277A showed similar sphingomyelinase activity but at least 2 times more dermonecrotic activity than rLiD1 (wild-type protein). Conversely, while the rLiD1W280A displayed a slight increase in sphingomyelinase activity, its biological activity was similar or lower compared to rLiD1, potentially due to its decreased thermostability and formation of amyloid aggregates. In conclusion, these new findings provide evidence that SMD-tail mutants impact the structure and function of these proteins and point out that residues outside the active site can even increase the function of these enzymes.
Assuntos
Fosfolipase D , Venenos de Aranha , Aranhas , Animais , Fosfolipase D/genética , Fosfolipase D/química , Fosfolipase D/metabolismo , Domínio Catalítico , Esfingomielina Fosfodiesterase , Diester Fosfórico Hidrolases/genética , Mutação , Proteínas Recombinantes/genética , Proteínas Recombinantes/química , Aranhas/genética , Venenos de Aranha/genética , Venenos de Aranha/químicaRESUMO
Loxosceles spp. (brown spiders) bites are responsible for the development of a syndrome consisting mainly of dermonecrotic lesions, and also systemic effects. Rabbits are one of the main experimental models used for better understanding the systemic and local effects of Loxosceles venom. The aim of this study is to evaluate the toxic and protective effects of rabbits immunized with Loxosceles spp. venom. Male New Zealand rabbits were allocated as a control group (CG; n = 5) that received adjuvant (Montanide) and phosphate-buffer saline (PBS), or as venom group (VG; n = 5) that received 21 µg of Loxosceles venom using Montanide as adjuvant. After five immunization cycles, a trial with 7 µg of Loxosceles intermedia (L. intermedia) venom was performed, and dermonecrotic lesions were measured. The rabbits were then euthanized, and their organs were collected for histopathology analysis. Rabbits that had undergone Loxosceles venom immunization protocol showed minor clinical disturbances during the experimental period. The used immunization protocol protected the rabbits against the toxic effect of the Loxosceles venom because they showed minor clinical disturbances during the experimental period.
RESUMO
Bites of brown spiders (Loxosceles spp.) are responsible for dermonecrotic lesions and potentially systemic envenoming that can lead to death. The only effective therapy is the use of the antivenom, usually produced in horses. However, little is known about the consequences of the systematic use of the Loxosceles venom and adjuvants and of the bleedings on antivenom-producing horses. Thus, the aim of this study was to evaluate the clinical changes in horses in their first immunization protocol for Loxosceles antivenom production. Eleven healthy horses, never immunized, were evaluated in three different periods: T0 (before immunization); T1 (after their first venom immunization); and T2 (after their first bleeding). Horses were clinically evaluated, sampled for blood, and underwent electrocardiographic (ECG) recordings. Several suppurated subcutaneous abscesses occurred due to the use of Freund's adjuvants and thrombophlebitis due to systematic venipunctures for the bleeding procedures. ECG showed arrhythmias in few horses in T2, such as an increase in T and R waves. In summary, the immunization protocol impacted on horses' health, especially after bleeding for antivenom procurement.
Assuntos
Venenos de Aranha , Aranhas , Animais , Antivenenos/farmacologia , Cavalos , Imunização/veterinária , Diester Fosfórico HidrolasesRESUMO
ABSTRACT Background: Although loxoscelism (bites by brown spiders of the genus Loxosceles) frequently results in dermonecrosis, no previous clinical reports have provided detailed temporal photodocumentation of the evolution of dermonecrotic lesions in a case series. Methods This was a retrospective cohort study involving a case series of loxoscelism. Only cases of dermonecrosis with photodocumentation of lesion evolution (from admission until complete or almost complete healing) were included. Results: Eight patients (six men, two women; median age, 38 years) fulfilled the inclusion criteria. The bite sites included the thigh (n = 4), forearm (n = 2), abdomen (n = 1), and trunk (n = 1). Time interval between the bite and first contact with our service ranged from 15 to 216 h (median = 29 h). The main clinical manifestations included local erythematous and ischemic violaceous lesions overlying a base of indurated edema (livedoid plaque, 8), local pain (8), exanthema (6), serohemorrhagic vesicles/blisters (5), fever (5), and jaundice (1). Based on a previously established classification, the cases were classified as probable cutaneous-necrotic loxoscelism (CNL, n = 4), presumptive CNL (n = 3), and presumptive cutaneous-hemolytic loxoscelism (n = 1). Seven patients were treated with anti-arachnidic antivenom (AV; median time post-bite = 46 h). Complete lesion healing ranged from 34 to 98 days post-bite (median, 68 days; six patients). None of the patients required reconstructive plastic surgery. Conclusions The sequential photographic documentation showed considerable variation in the process of wound healing, with complete epithelialization requiring up to 3 months after the bite.
RESUMO
The genus Loxosceles comprises 140 species widely distributed around the world. These spiders are nocturnal, sedentary and remarkably nonaggressive, although they cause accidents in humans with wide degrees of severity, generating signs and symptoms that define the clinical condition known as loxoscelism. Its local signs and symptoms were first reported in 1872, and over the years, a large medical literature has been accumulated; unfortunately, it is not always trustworthy. Assessing the reliability of such information, we reviewed 120 case reports of loxoscelism published in 84 articles over the past 20 years. This search allowed us to gather information on the clinical aspects, diagnosis and treatment of loxoscelism, showing that the severity of these accidents has multiple degrees and that it is influenced by many factors. Thus, coupled with epidemiological and species occurrence information, this study can be a useful tool for the clinical practice of loxoscelism. It may support and provide a multidisciplinary view that should be taken into consideration when establishing the therapeutic approach in cases of Loxosceles envenomation.
Assuntos
Picada de Aranha/diagnóstico , Aranhas , Animais , Humanos , Diester Fosfórico Hidrolases , Reprodutibilidade dos Testes , Picada de Aranha/epidemiologia , Picada de Aranha/terapiaRESUMO
The genus Loxosceles comprises 140 species widely distributed around the world. These spiders are nocturnal, sedentary and remarkably nonaggressive, although they cause accidents in humans with wide degrees of severity, generating signs and symptoms that define the clinical condition known as loxoscelism. Its local signs and symptoms were first reported in 1872, and over the years, a large medical literature has been accumulated; unfortunately, it is not always trustworthy. Assessing the reliability of such information, we reviewed 120 case reports of loxoscelism published in 84 articles over the past 20 years. This search allowed us to gather information on the clinical aspects, diagnosis and treatment of loxoscelism, showing that the severity of these accidents has multiple degrees and that it is influenced by many factors. Thus, coupled with epidemiological and species occurrence information, this study can be a useful tool for the clinical practice of loxoscelism. It may support and provide a multidisciplinary view that should be taken into consideration when establishing the therapeutic approach in cases of Loxosceles envenomation.
RESUMO
Os acidentes causados por aranhas do gênero Loxosceles têm importância na clínica de pequenos animais, mesmo não havendo dados epidemiológicos desses ataques em animais de estimação, dada a gravidade da lesão e possíveis complicações sistêmicas resultantes, tornando indispensável maior conhecimento sobre a espécie e as consequências do envenenamento. O presente trabalho relata a presença de uma lesão dermonecrótica em um felino atribuída a aranha-marrom (Loxosceles sp). O atendimento ocorreu na clínica Empório de Bicho em Caxias do Sul, no estado do Rio Grande do Sul. O animal apresentava uma lesão necrótica em região perineal, com fibrina e secreção purulenta. O tratamento consistiu no uso clorexidina para limpeza, hidrogel, açúcar, Fitofix® e Dersani® como promotores de cicatrização. Após um mês de tratamento, o animal apresentava uma melhora satisfatória.(AU)
Accidents caused by spiders of the genus Loxosceles are important in the small animal clinic, even though there are no epidemiological data on these attacks in pets, given the severity of the lesion and possible systemic complications, it becomes necessary to know more about the species and the consequences of the poisoning. The present work reports the presence of a dermonecrotic lesion in a cat attributed to brown spider (Loxosceles sp). The patient had a necrotic lesion in the perineal region with fibrin and purulent secretion. The treatment consisted of using chlorhexidine for cleaning, hydrogel, sugar, Fitofix® and Dersani® as healing promoters. After one month of treatment, the animal showed a satisfactory improvement.(AU)
Assuntos
Animais , Gatos , Aranha Marrom Reclusa , Necrose/tratamento farmacológico , Necrose/veterinária , Venenos de Aranha/intoxicação , Animais Peçonhentos , Períneo/patologiaRESUMO
Os acidentes causados por aranhas do gênero Loxosceles têm importância na clínica de pequenos animais, mesmo não havendo dados epidemiológicos desses ataques em animais de estimação, dada a gravidade da lesão e possíveis complicações sistêmicas resultantes, tornando indispensável maior conhecimento sobre a espécie e as consequências do envenenamento. O presente trabalho relata a presença de uma lesão dermonecrótica em um felino atribuída a aranha-marrom (Loxosceles sp). O atendimento ocorreu na clínica Empório de Bicho em Caxias do Sul, no estado do Rio Grande do Sul. O animal apresentava uma lesão necrótica em região perineal, com fibrina e secreção purulenta. O tratamento consistiu no uso clorexidina para limpeza, hidrogel, açúcar, Fitofix® e Dersani® como promotores de cicatrização. Após um mês de tratamento, o animal apresentava uma melhora satisfatória.
Accidents caused by spiders of the genus Loxosceles are important in the small animal clinic, even though there are no epidemiological data on these attacks in pets, given the severity of the lesion and possible systemic complications, it becomes necessary to know more about the species and the consequences of the poisoning. The present work reports the presence of a dermonecrotic lesion in a cat attributed to brown spider (Loxosceles sp). The patient had a necrotic lesion in the perineal region with fibrin and purulent secretion. The treatment consisted of using chlorhexidine for cleaning, hydrogel, sugar, Fitofix® and Dersani® as healing promoters. After one month of treatment, the animal showed a satisfactory improvement.
Assuntos
Animais , Gatos , Aranha Marrom Reclusa , Necrose/tratamento farmacológico , Necrose/veterinária , Venenos de Aranha/intoxicação , Animais Peçonhentos , Períneo/patologiaRESUMO
Hemorrhage is the most prominent effect of snake venom metalloproteinases (SVMPs) in human envenomation. The capillary injury is a multifactorial effect caused by hydrolysis of the components of the basement membrane (BM). The PI and PIII classes of SVMPs are abundant in viperid venoms and hydrolyze BM components. However, hemorrhage is associated mostly with PIII-class SVMPs that contain non-catalytic domains responsible for the binding of SVMPs to BM proteins, facilitating enzyme accumulation in the tissue and enhancing its catalytic efficiency. Here we report on Atroxlysin-Ia, a PI-class SVMP that induces hemorrhagic lesions in levels comparable to those induced by Batroxrhagin (PIII-class), and a unique SVMP effect characterized by the rapid onset of dermonecrotic lesions. Atroxlysin-Ia was purified from B. atrox venom, and sequence analyses indicated that it is devoid of non-catalytic domains and unable to bind to BM proteins as collagen IV and laminin in vitro or in vivo. The presence of Atroxlysin-Ia was diffuse in mice skin, and localized mainly in the epidermis with no co-localization with BM components. Nevertheless, the skin lesions induced by Atroxlysin-Ia were comparable to those induced by Batroxrhagin, with induction of leukocyte infiltrates and hemorrhagic areas soon after toxin injection. Detachment of the epidermis was more intense in skin injected with Atroxlysin-Ia. Comparing the catalytic activity of both toxins, Batroxrhagin was more active in the hydrolysis of a peptide substrate while Atroxlysin-Ia hydrolyzed more efficiently fibrin, laminin, collagen IV and nidogen. Thus, the results suggest that Atroxlysin-Ia bypasses the binding step to BM proteins, essential for hemorrhagic lesions induced by PII- and P-III class SVMPs, causing a significantly fast onset of hemorrhage and dermonecrosis, due to its higher proteolytic capacity on BM components.
Assuntos
Músculos Abdominais/efeitos dos fármacos , Bothrops , Hemorragia/induzido quimicamente , Metaloproteases/toxicidade , Pele/efeitos dos fármacos , Venenos de Serpentes/enzimologia , Músculos Abdominais/patologia , Animais , Membrana Basal/efeitos dos fármacos , Membrana Basal/metabolismo , Proteínas da Matriz Extracelular/metabolismo , Feminino , Hemorragia/patologia , Hidrólise , Masculino , Camundongos , Necrose/induzido quimicamente , Necrose/patologia , Pele/patologiaRESUMO
Sphingomyelinases D have only been identified in arachnid venoms, Corynebacteria, Arcanobacterium, Photobacterium and in the fungi Aspergillus and Coccidioides. The arachnid and bacterial enzymes share very low sequence identity and do not contain the HKD sequence motif characteristic of the phospholipase D superfamily, however, molecular modeling and circular dichroism of SMases D from Loxosceles intermedia and Corynebacterium pseudotuberculosis indicate similar folds. The phospholipase, hemolytic and necrotic activities and mice vessel permeabilities were compared and both enzymes possess the ability to hydrolyze phospholipids and also promote similar pathological reactions in the host suggesting the existence of a common underlying mechanism in tissue disruption. J. Cell. Biochem. 118:2053-2063, 2017. © 2016 Wiley Periodicals, Inc.
Assuntos
Proteínas de Artrópodes/toxicidade , Proteínas de Bactérias/toxicidade , Permeabilidade Capilar/efeitos dos fármacos , Corynebacterium pseudotuberculosis/química , Diester Fosfórico Hidrolases/toxicidade , Aranhas/química , Sequência de Aminoácidos , Animais , Proteínas de Artrópodes/genética , Proteínas de Artrópodes/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Clonagem Molecular , Corynebacterium pseudotuberculosis/enzimologia , Corynebacterium pseudotuberculosis/patogenicidade , Eritrócitos/efeitos dos fármacos , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Hemólise/efeitos dos fármacos , Cavalos , Humanos , Camundongos , Diester Fosfórico Hidrolases/genética , Diester Fosfórico Hidrolases/metabolismo , Coelhos , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Proteínas Recombinantes/toxicidade , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Carneiro Doméstico , Pele/efeitos dos fármacos , Pele/patologia , Aranhas/enzimologia , Aranhas/patogenicidadeRESUMO
The pathogenesis of dermonecrosis induced by the venom of the African spitting cobra Naja nigricollis was investigated in a mouse model. Intradermal injection of venom induced a macroscopic necrotic lesion. Histological examination revealed early edema of the dermis, followed by blistering, loss of skin appendages and reduction in cellularity. By 24 h, necrosis of the dermis was evident, sections of epidermis were lost, and a fibrinoid hyaline material filled the damaged areas. Abundant inflammatory infiltrate was present in the hypodermis and basal dermis, and there was an increment in the expression of matrix metalloproteinases (MMPs). Thrombi were observed in blood vessels. Abundant cells were present in the dermis by 7 days. By 14 and 28 days, re-epithelization had occurred, collagen was widespread in the dermis, and few skin appendages were present. The RP-HPLC fractions that reproduced the necrotic activity were composed of low molecular mass cytotoxins of the three-finger toxin family and, to a lesser extent, of phospholipases A2 (PLA2). Inhibition of PLA2 of venom by p-bromophenacyl bromide did not reduce the area of necrosis, but modified the appearance of necrotic regions. Depletion of neutrophils and inhibition of venom metalloproteinases and tissue MMPs did not affect dermonecrosis. IgG and F(ab')2 antivenoms were effective in the neutralization of dermonecrosis when incubated with venom prior to injection. However, when antivenoms were administered immediately after venom injection, dermonecrosis was reduced only to a partial extent, underscoring the difficulties in neutralizing this effect with antivenoms.
Assuntos
Venenos Elapídicos/toxicidade , Pele/efeitos dos fármacos , Sequência de Aminoácidos , Animais , Antivenenos/administração & dosagem , Cromatografia Líquida de Alta Pressão , Venenos Elapídicos/química , Camundongos , Necrose , Neutrófilos/imunologia , Fenilalanina/análogos & derivados , Fenilalanina/farmacologia , Pele/imunologia , Pele/patologia , Tiofenos/farmacologiaRESUMO
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.
Assuntos
Plaquetas/fisiologia , Endotélio Vascular/efeitos dos fármacos , Diester Fosfórico Hidrolases/toxicidade , Dermatopatias/sangue , Dermatopatias/patologia , Pele/efeitos dos fármacos , Venenos de Aranha/toxicidade , Animais , Contagem de Células Sanguíneas , Modelos Animais de Doenças , Endotélio Vascular/metabolismo , Necrose , Neutrófilos/efeitos dos fármacos , Fagocitose/efeitos dos fármacos , Tempo de Protrombina , Coelhos , Pele/irrigação sanguínea , Pele/patologia , Dermatopatias/induzido quimicamente , Trombocitopenia/sangue , Fator de von Willebrand/análiseRESUMO
The Loxosceles genus spiders (the brown spiders) are encountered in all the continents, and the clinical manifestations following spider bites include skin necrosis with gravitational lesion spreading and occasional systemic manifestations, such as intravascular hemolysis, thrombocytopenia and acute renal failure. Brown spider venoms are complex mixtures of toxins especially enriched in three molecular families: the phospholipases D, astacin-like metalloproteases and Inhibitor Cystine Knot (ICK) peptides. Other toxins with low level of expression also present in the venom include the serine proteases, serine protease inhibitors, hyaluronidases, allergen factors and translationally controlled tumor protein (TCTP). The mechanisms by which the Loxosceles venoms act and exert their noxious effects are not fully understood. Except for the brown spider venom phospholipase D, which causes dermonecrosis, hemolysis, thrombocytopenia and renal failure, the pathological activities of the other venom toxins remain unclear. The objective of the present review is to provide insights into the brown spider venoms and loxoscelism based on recent results. These insights include the biology of brown spiders, the clinical features of loxoscelism and the diagnosis and therapy of brown spider bites. Regarding the brown spider venom, this review includes a description of the novel toxins revealed by molecular biology and proteomics techniques, the data regarding three-dimensional toxin structures, and the mechanism of action of these molecules. Finally, the biotechnological applications of the venom components, especially for those toxins reported as recombinant molecules, and the challenges for future study are discussed.
Assuntos
Venenos de Aranha/toxicidade , Aranhas/química , Animais , Antivenenos/química , Proteínas de Artrópodes/química , Proteínas de Artrópodes/isolamento & purificação , Proteínas de Artrópodes/toxicidade , Biomarcadores Tumorais/química , Biomarcadores Tumorais/isolamento & purificação , Feminino , Humanos , Hialuronoglucosaminidase/química , Hialuronoglucosaminidase/isolamento & purificação , Hialuronoglucosaminidase/toxicidade , Masculino , Modelos Moleculares , Fosfolipase D/química , Fosfolipase D/isolamento & purificação , Fosfolipase D/toxicidade , Proteômica , Serina Proteases/química , Serina Proteases/isolamento & purificação , Serina Proteases/toxicidade , Picada de Aranha/patologia , Venenos de Aranha/química , Venenos de Aranha/imunologia , Aranhas/anatomia & histologia , Aranhas/fisiologia , Proteína Tumoral 1 Controlada por TraduçãoRESUMO
Loxosceles venom comprises a mixture of diverse toxins that induces intense local inflammatory reaction, dermonecrotic injury, platelet aggregation, hemolytic anemia and acute renal failure. Among several toxins in the venom, phospholipases D (PLDs), also called dermonecrotic toxins, are the most important and best studied, since they account for the main effects observed in loxoscelism. Despite their importance, biological analysis of PLDs is hampered by the minute amounts normally purified from the venom, and therefore many efforts have been made to clone those toxins. However, to date, no PLD from Loxosceles gaucho has been obtained in a heterologous system. Thus, in this work we show the cloning of a PLD from L. gaucho venom gland, named LgRec1, which was successfully expressed in a bacterial system. LgRec1 evoked local reaction (edema, erythema, ecchymosis, and paleness), dermonecrosis and hemolysis. It was also able to hydrolyze sphingomyelin and promote platelet aggregation. ELISA and Western blot analysis showed that LgRec1 was recognized by an anti-L. gaucho venom serum, a commercial arachnidic antivenom as well as a monoclonal antibody raised against the dermonecrotic fraction of L. gaucho venom. In addition, LgRec1 demonstrated to be highly immunogenic and antibodies raised against this recombinant toxin inhibited local reaction (~65%) and dermonecrosis (~100%) elicited by L. gaucho whole venom. Since PLDs are considered the major components accounting for the local and systemic envenomation effects caused by spiders from genus Loxosceles, the information provided here may help to understand the mechanisms behind clinical symptomatology.
Assuntos
Fosfolipase D/genética , Venenos de Aranha/genética , Sequência de Aminoácidos , Animais , Anticorpos Neutralizantes/imunologia , Sequência de Bases , Clonagem Molecular , Reações Cruzadas , Expressão Gênica , Hemólise/efeitos dos fármacos , Humanos , Dados de Sequência Molecular , Fosfolipase D/imunologia , Fosfolipase D/metabolismo , Fosfolipase D/farmacologia , Agregação Plaquetária/efeitos dos fármacos , Coelhos , Alinhamento de Sequência , Esfingomielina Fosfodiesterase/metabolismo , Relação Estrutura-AtividadeRESUMO
Envenomation by Loxosceles bites is characterized by dermonecrotic and/or systemic features that lead to several clinical signs and symptoms called loxoscelism. Dermonecrotic lesions are preceded by thrombosis of the dermal plexus. Recent studies show that atheromatous plaque is prone to thrombosis due to endothelial cell apoptosis. To the best of our knowledge, there are no reports of microscopic dermal lesion and endothelial cell apoptosis induced by Loxosceles similis venom in the literature. Thus, the aim of the present study is to describe histological lesions induced by L. similis venom in rabbit skin and to elucidate whether apoptosis of endothelial cells is involved in the pathogenesis of loxoscelism. Forty male rabbits were split into two groups: the control group (intradermally injected with 50 µL of PBS) and the experimental group (intradermally injected with 0.5 µg of L. similis crude venom diluted in 50 µL of PBS). After 2, 4, 6 and 8 hours of injection, skin fragments were collected and processed for paraffin or methacrylate embedding. Sections of 5 µm thick were stained by HE, PAS or submitted to TUNEL reaction. Microscopically, severe edema, diffuse heterophilic inflammatory infiltrate, perivascular heterophilic infiltrate, thrombosis, fibrinoid necrosis of arteriolar wall and cutaneous muscle necrosis were observed. Two hours after venom injection, endothelial cells with apoptosis morphology were evidenced in the dermal plexus. Apoptosis was confirmed by TUNEL reaction. It seems that endothelial cell apoptosis and its consequent desquamation is an important factor that induces thrombosis and culminates in dermonecrosis, which is characteristic of cutaneous loxoscelism.
Assuntos
Animais , Masculino , Coelhos , Intoxicação/patologia , Pele/patologia , Venenos de Aranha , Coelhos/lesõesRESUMO
Envenomation by Loxosceles bites is characterized by dermonecrotic and/or systemic features that lead to several clinical signs and symptoms called loxoscelism. Dermonecrotic lesions are preceded by thrombosis of the dermal plexus. Recent studies show that atheromatous plaque is prone to thrombosis due to endothelial cell apoptosis. To the best of our knowledge, there are no reports of microscopic dermal lesion and endothelial cell apoptosis induced by Loxosceles similis venom in the literature. Thus, the aim of the present study is to describe histological lesions induced by L. similis venom in rabbit skin and to elucidate whether apoptosis of endothelial cells is involved in the pathogenesis of loxoscelism. Forty male rabbits were split into two groups: the control group (intradermally injected with 50 µL of PBS) and the experimental group (intradermally injected with 0.5 µg of L. similis crude venom diluted in 50 µL of PBS). After 2, 4, 6 and 8 hours of injection, skin fragments were collected and processed for paraffin or methacrylate embedding. Sections of 5 µm thick were stained by HE, PAS or submitted to TUNEL reaction. Microscopically, severe edema, diffuse heterophilic inflammatory infiltrate, perivascular heterophilic infiltrate, thrombosis, fibrinoid necrosis of arteriolar wall and cutaneous muscle necrosis were observed. Two hours after venom injection, endothelial cells with apoptosis morphology were evidenced in the dermal plexus. Apoptosis was confirmed by TUNEL reaction. It seems that endothelial cell apoptosis and its consequent desquamation is an important factor that induces thrombosis and culminates in dermonecrosis, which is characteristic of cutaneous loxoscelism.(AU)