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Denise V. Tambourgi - One of the best experts on this subject based on the ideXlab platform.
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Searching for the toxic potential of Loxosceles amazonica and Loxosceles willianilsoni spiders' venoms.
Toxicon : official journal of the International Society on Toxinology, 2020Co-Authors: Priscila Hess Lopes, Caroline Sayuri Fukushima, Rogério Bertani, Rosana Shoji, Denise V. TambourgiAbstract:Abstract The Loxosceles genus belongs to the Sicariidae family and it comprises species whose venom can cause accidents with potentially fatal consequences. We have previously shown that SMase D is the enzyme responsible for the main pathological effects of Loxosceles venom. Despite the severity of accidents with Loxosceles, few species are considered to be of medical importance. Little is known about the venom of non-synanthropic species that live in natural environments. To contribute to a better understanding about the venom's toxicity of Loxosceles genus, the aim of this study was to (i) characterize the toxic properties of Loxosceles amazonica from two different localities and a recent described cave species Loxosceles willianilsoni and (ii) compare these venoms with that from Loxosceles laeta, which is among the most toxic ones. We show here that both L. amazonica venoms (from the two studied locations) and L. willianilsoni presented SMase D activity similar to that exhibited by L. laeta venom. Although L. amazonica and L. willianilsoni venoms were able to induce complement dependent human erythrocytes lysis, they were not able to induce cell death of human keratinocytes, as promoted by L. laeta venom, in the concentrations tested. These results indicate that other species of Loxosceles, in addition to those classified as medically important, have toxic potential to cause accidents in humans, despite interspecific variations that denote possible less toxicity.
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Targeting Loxosceles spider Sphingomyelinase D with small-molecule inhibitors as a potential therapeutic approach for loxoscelism
2019Co-Authors: Priscila Hess Lopes, Mário T. Murakami, Fernanda C. V. Portaro, Kerly Fernanda Mesquita Pasqualoto, Carmen Van Den Berg, Denise V. TambourgiAbstract:Loxosceles spiders’ venoms consist of a mixture of proteins, including the sphingomyelinases D (SMases D), which are the main toxic components responsible for local and systemic effects in human envenomation. Herein, based on the structural information of SMase D from Loxosceles laeta spider venom and virtual docking-based screening approach, three benzene sulphonate compounds (named 1, 5 and 6) were identified as potential Loxosceles SMase D inhibitors. All compounds inhibited the hydrolysis of the sphingomyelin substrate by both recombinant and native SMases D. Compounds 5 and 6 acted as SMases D uncompetitive inhibitors with Ki values of 0.49 µM and 0.59 µM, respectively. Compound 1 is a mixed type inhibitor, and presented a Ki value of 0.54 µM. In addition, the three compounds inhibited the binding of SMases D to human erythrocytes and the removal of glycophorin C from the cell surface, which are important events in the complement-dependent haemolysis induced by Loxosceles venom. Moreover, compounds 5 and 6 reduced the binding of SMases to human keratinocytes membrane and the venom induced cell death. Importantly, compounds 5 and 6 also controlled the development of the necrotic lesion in an in vivo model of loxoscelism. Together, our findings indicate that the novel SMase D inhibitors presented here are able to suppress both local and systemic reactions induced by Loxosceles venoms. Since the number of Loxosceles envenomation accidents is currently growing worldwide, our results indicate that both inhibitors are promising scaffolds for the rational design of new drugs targeting SMases D from these spiders.
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Loxosceles venom Sphingomyelinase D activates human blood leukocytes: Role of the complement system.
Molecular immunology, 2017Co-Authors: Daniel Manzoni-de-almeida, Priscila Hess Lopes, Carmen W. Van Den Berg, Carla Cristina Squaiella-baptistão, Denise V. TambourgiAbstract:Envenomation by Loxosceles spiders can result in severe systemic and local reactions, which are mainly triggered by Sphingomyelinase D (SMase D), a toxic component of Loxosceles venom. SMase D induces a systemic inflammatory condition similar to the reaction observed during an endotoxic shock. Considering the potent pro-inflammatory potential of Loxosceles venom and the SMase D, in this study we have used the whole human blood model to study the endotoxic-like shock triggered by SMase D. Recombinant purified SMase D from L. intermedia venom, similarly to LPS, induced activation of blood leukocytes, as observed by the increase in the expression of CD11b and TLR4, production of reactive oxygen and nitrogen species (superoxide anion and peroxynitrite) and release of TNF-α. Complement consumption in the plasma was also detected, and complement inhibition by compstatin decreased the SMase D and LPS-induced leukocyte activation, as demonstrated by a reduction in the expression of CD11b and TLR4 and superoxide anion production. Similar results were found for the L. intermedia venom, except for the production of TNF-α. These findings indicate that SMase D present in Loxosceles venom is able to activate leukocytes in a partially complement-dependent manner, which can contribute to the systemic inflammation that follows envenomation by this spider. Thus, future therapeutic management of systemic Loxosceles envenomation could include the use of complement inhibitors as adjunct therapy.
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Tetracycline Reduces Kidney Damage Induced by Loxosceles Spider Venom.
Toxins, 2017Co-Authors: Cinthya Kimori Okamoto, Carmen W. Van Den Berg, Rute M. Gonçalves-de-andrade, Mizuno Masashi, Denise V. TambourgiAbstract:Envenomation by Loxosceles spider can result in two clinical manifestations: cutaneous and systemic loxoscelism, the latter of which includes renal failure. Although incidence of renal failure is low, it is the main cause of death, occurring mainly in children. The sphingomyelinase D (SMase D) is the main component in Loxosceles spider venom responsible for local and systemic manifestations. This study aimed to investigate the toxicity of L. intermedia venom and SMase D on kidney cells, using both In vitro and in vivo models, and the possible involvement of endogenous metalloproteinases (MMP). Results demonstrated that venom and SMase D are able to cause death of human kidney cells by apoptosis, concomitant with activation and secretion of extracellular matrix metalloproteases, MMP-2 and MMP-9. Furthermore, cell death and MMP synthesis and secretion can be prevented by tetracycline. In a mouse model of systemic loxoscelism, Loxosceles venom-induced kidney failure was observed, which was abrogated by administration of tetracycline. These results indicate that MMPs may play an important role in Loxosceles venom-induced kidney injury and that tetracycline administration may be useful in the treatment of human systemic loxoscelism.
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Microcirculation abnormalities provoked by Loxosceles spiders' envenomation
Toxicon : official journal of the International Society on Toxinology, 2015Co-Authors: Kátia Cristina De Oliveira-lima, Rute Maria Goncalves De Andrade, Priscila Hess Lopes, Carmen W. Van Den Berg, Sandra Helena Poliselli Farsky, Denise V. TambourgiAbstract:Loxoscelism is caused by envenomation by spiders from Loxosceles genus. Clinical symptoms only appear a few hours after envenomation and can evolve in local reactions, such as dermonecrosis, and systemic reactions, including intravascular haemolysis, intravascular coagulation and renal failure. Considering that alterations in the microcirculatory network are involved in the pathogenesis of different diseases, including the inflammatory process, the aim of this study was to investigate the action of venoms of males and females of Loxosceles intermedia and Loxosceles laeta on the microcirculatory network and examine the systemic production of inflammatory mediators in a murine model of loxoscelism. We observed that during systemic envenomation, the alterations in the microcirculation include increase in the number of rolling cells, which was more intense in animals injected with female Loxosceles spider venoms. This positively correlated with increase in TNF-α and NO serum levels, induction of which was higher by female venoms when compared with male venoms. The increase of leukocytes rolling was not accompanied by increase of cell adhesion. The absence of leukocyte extravasation may explain why in mice, in contrast to humans, no cutaneous loxoscelism occurs. Thus, targeting the neutrophil adhesion and extravasation in Loxosceles envenomed patients may prevent cutaneous pathology.
Carmen W. Van Den Berg - One of the best experts on this subject based on the ideXlab platform.
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Loxosceles venom Sphingomyelinase D activates human blood leukocytes: Role of the complement system.
Molecular immunology, 2017Co-Authors: Daniel Manzoni-de-almeida, Priscila Hess Lopes, Carmen W. Van Den Berg, Carla Cristina Squaiella-baptistão, Denise V. TambourgiAbstract:Envenomation by Loxosceles spiders can result in severe systemic and local reactions, which are mainly triggered by Sphingomyelinase D (SMase D), a toxic component of Loxosceles venom. SMase D induces a systemic inflammatory condition similar to the reaction observed during an endotoxic shock. Considering the potent pro-inflammatory potential of Loxosceles venom and the SMase D, in this study we have used the whole human blood model to study the endotoxic-like shock triggered by SMase D. Recombinant purified SMase D from L. intermedia venom, similarly to LPS, induced activation of blood leukocytes, as observed by the increase in the expression of CD11b and TLR4, production of reactive oxygen and nitrogen species (superoxide anion and peroxynitrite) and release of TNF-α. Complement consumption in the plasma was also detected, and complement inhibition by compstatin decreased the SMase D and LPS-induced leukocyte activation, as demonstrated by a reduction in the expression of CD11b and TLR4 and superoxide anion production. Similar results were found for the L. intermedia venom, except for the production of TNF-α. These findings indicate that SMase D present in Loxosceles venom is able to activate leukocytes in a partially complement-dependent manner, which can contribute to the systemic inflammation that follows envenomation by this spider. Thus, future therapeutic management of systemic Loxosceles envenomation could include the use of complement inhibitors as adjunct therapy.
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Tetracycline Reduces Kidney Damage Induced by Loxosceles Spider Venom.
Toxins, 2017Co-Authors: Cinthya Kimori Okamoto, Carmen W. Van Den Berg, Rute M. Gonçalves-de-andrade, Mizuno Masashi, Denise V. TambourgiAbstract:Envenomation by Loxosceles spider can result in two clinical manifestations: cutaneous and systemic loxoscelism, the latter of which includes renal failure. Although incidence of renal failure is low, it is the main cause of death, occurring mainly in children. The sphingomyelinase D (SMase D) is the main component in Loxosceles spider venom responsible for local and systemic manifestations. This study aimed to investigate the toxicity of L. intermedia venom and SMase D on kidney cells, using both In vitro and in vivo models, and the possible involvement of endogenous metalloproteinases (MMP). Results demonstrated that venom and SMase D are able to cause death of human kidney cells by apoptosis, concomitant with activation and secretion of extracellular matrix metalloproteases, MMP-2 and MMP-9. Furthermore, cell death and MMP synthesis and secretion can be prevented by tetracycline. In a mouse model of systemic loxoscelism, Loxosceles venom-induced kidney failure was observed, which was abrogated by administration of tetracycline. These results indicate that MMPs may play an important role in Loxosceles venom-induced kidney injury and that tetracycline administration may be useful in the treatment of human systemic loxoscelism.
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Microcirculation abnormalities provoked by Loxosceles spiders' envenomation
Toxicon : official journal of the International Society on Toxinology, 2015Co-Authors: Kátia Cristina De Oliveira-lima, Rute Maria Goncalves De Andrade, Priscila Hess Lopes, Carmen W. Van Den Berg, Sandra Helena Poliselli Farsky, Denise V. TambourgiAbstract:Loxoscelism is caused by envenomation by spiders from Loxosceles genus. Clinical symptoms only appear a few hours after envenomation and can evolve in local reactions, such as dermonecrosis, and systemic reactions, including intravascular haemolysis, intravascular coagulation and renal failure. Considering that alterations in the microcirculatory network are involved in the pathogenesis of different diseases, including the inflammatory process, the aim of this study was to investigate the action of venoms of males and females of Loxosceles intermedia and Loxosceles laeta on the microcirculatory network and examine the systemic production of inflammatory mediators in a murine model of loxoscelism. We observed that during systemic envenomation, the alterations in the microcirculation include increase in the number of rolling cells, which was more intense in animals injected with female Loxosceles spider venoms. This positively correlated with increase in TNF-α and NO serum levels, induction of which was higher by female venoms when compared with male venoms. The increase of leukocytes rolling was not accompanied by increase of cell adhesion. The absence of leukocyte extravasation may explain why in mice, in contrast to humans, no cutaneous loxoscelism occurs. Thus, targeting the neutrophil adhesion and extravasation in Loxosceles envenomed patients may prevent cutaneous pathology.
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Tetracycline Protects against Dermonecrosis Induced by Loxosceles Spider Venom
The Journal of investigative dermatology, 2007Co-Authors: Danielle Paixao-cavalcante, Rute M. Gonçalves-de-andrade, Carmen W. Van Den Berg, Matheus F. Fernandes-pedrosa, Cinthya Kimori Okamoto, Denise V. TambourgiAbstract:Envenomation by spiders belonging to the Loxosceles genus (brown spider) often results in local dermonecrotic lesions. We have previously shown that Loxosceles sphingomyelinase D (SMase D), the venom component responsible for all the pathological effects, induced the expression of matrix metalloproteinases (MMPs) in rabbits and in human keratinocytic cells. We also showed that the SMase D-induced apoptosis and MMP expression of keratinocytes was inhibited by tetracyclines. We have further investigated the ability of tetracyclines to inhibit or prevent the dermonecrotic lesion induced by Loxosceles venom in vivo and in vitro models. Primary cultures of rabbit fibroblasts incubated with increasing concentrations of venom or SMase D showed a decrease in cell viability, which was prevented by tetracyclines. In vivo experiments showed that topical treatments with tetracycline of rabbits, inoculated with crude Loxosceles intermedia venom or recombinant SMase D, significantly reduced the progression of the dermonecrotic lesion. Furthermore, tetracyclines also reduced the expression of MMP-2 and prevented the induction of MMP-9. Our results suggest that tetracycline may be an effective therapeutic agent for the treatment of cutaneous loxoscelism.
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Tetracycline protects against dermonecrosis induced by Loxosceles spider venom. Commentary
Journal of Investigative Dermatology, 2007Co-Authors: Lloyd E. King, Rute M. Gonçalves-de-andrade, Carmen W. Van Den Berg, Danielle Paixao-cavalcante, Matheus F. Fernandes-pedrosa, Cinthya Kimori Okamoto, Denise V. TambourgiAbstract:Envenomation by spiders belonging to the Loxosceles genus (brown spider) often results in local dermonecrotic lesions. We have previously shown that Loxosceles sphingomyelinase D (SMase D), the venom component responsible for all the pathological effects, induced the expression of matrix metalloproteinases (MMPs) in rabbits and in human keratinocytic cells. We also showed that the SMase D-induced apoptosis and MMP expression of keratinocytes was inhibited by tetracyclines. We have further investigated the ability of tetracyclines to inhibit or prevent the dermonecrotic lesion induced by Loxosceles venom in vivo and in vitro models. Primary cultures of rabbit fibroblasts incubated with increasing concentrations of venom or SMase D showed a decrease in cell viability, which was prevented by tetracyclines. In vivo experiments showed that topical treatments with tetracycline of rabbits, inoculated with crude Loxosceles intermedia venom or recombinant SMase D, significantly reduced the progression of the dermonecrotic lesion. Furthermore, tetracyclines also reduced the expression of MMP-2 and prevented the induction of MMP-9. Our results suggest that tetracycline may be an effective therapeutic agent for the treatment of cutaneous loxoscelism.
Richard S. Vetter - One of the best experts on this subject based on the ideXlab platform.
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seasonality of brown recluse spiders Loxosceles reclusa submitted by the general public implications for physicians regarding loxoscelism diagnoses
Toxicon, 2011Co-Authors: Richard S. VetterAbstract:Many medically important animals exhibit fluctuating seasonal abundance such that risk from envenomation or disease is not constant throughout the year. As indicated by homeowner submissions, brown recluse spiders, Loxosceles reclusa, show seasonal peaks of activity during summer and paucity in winter. This information should be incorporated as part of the diagnostic algorithm for physicians when considering the probability of loxoscelism in endemic Loxosceles areas especially if a skin lesion occurs when spiders are scarce.
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Arachnids Submitted as Suspected Brown Recluse Spiders (Araneae: Sicariidae): Loxosceles Spiders Are Virtually Restricted to Their Known Distributions but Are Perceived to Exist Throughout the United States
Journal of medical entomology, 2005Co-Authors: Richard S. VetterAbstract:An Internet offer was made to identify any spider in the United States perceived to be a brown recluse spider, Loxosceles reclusa Gertsch & Mulaik (Sicariidae). In total, 1,773 arachnids from 49 states represented three orders (Araneae, Solifugae, and Opiliones) and the identifiable spiders (Araneae) consisted of 38 families, 88 genera, and 158 recognizable species. Participants from states at least half within the known brown recluse distribution submitted Loxosceles spiders 32–89% of the time, except Louisiana and Mississippi with no submissions. From 25 of 29 states completely or almost completely outside of the range of Loxosceles spiders, no recluse spiders were submitted. Only two discoveries of brown recluses and two of the worldwide tramp species Loxosceles rufescens (Dufour) were submitted from nonendemic Loxosceles areas. States on distribution margins of brown recluse or other native Loxosceles spiders were intermediate in their Loxosceles submissions. This study showed that 1) the general public perceives brown recluses to occur over wide-ranging areas of the United States; and 2) brown recluses are frequently submitted from endemic states and almost never from nonendemic states, and therefore are virtually limited to their known distributions. This study corroborates opinions that diagnosis of brown recluse spider bites is best restricted to areas historically supporting proven, widespread populations of Loxosceles spiders.
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Reports of envenomation by brown recluse spiders (Araneae: Sicariidae) outnumber verifications of Loxosceles spiders in Florida.
Journal of medical entomology, 2004Co-Authors: Richard S. Vetter, G. B. Edwards, Louis F. JamesAbstract:Abstract Bites attributed to the brown recluse spider, Loxosceles reclusa Gertsch & Mulaik, are frequently reported by medical personnel throughout Florida, whereas the extensive arachnological evidence contradicts the alleged widespread occurrence of Loxosceles spiders in the state. We compared reports of brown recluse spider bites made by medical personnel from a 6-yr Florida poison control center database to the known verifications of Loxosceles spiders from 100 yr of Florida arachnological data. Medical personnel diagnosed 124 brown recluse spider bites from 31 of Florida’s 67 counties in 6 yr. In contrast, only 11 finds of ≈70 Loxosceles spiders have been made in 10 Florida counties in 100 yr. Florida does not have sufficient widespread populations of Loxosceles spiders to warrant consideration of brown recluse spider envenomation as a probable etiology of dermonecrosis. Florida health care would improve if medical personnel would consider the multitude of other etiologies that manifest in dermonecrosis.
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diagnoses of brown recluse spider bites loxoscelism greatly outnumber actual verifications of the spider in four western american states
Toxicon, 2003Co-Authors: Richard S. Vetter, Paula E Cushing, Rodney L Crawford, Richard S. Vetter, Lynn A RoyceAbstract:We attempt to demonstrate that physicians overdiagnose loxoscelism (colloquially known as 'brown recluse spider bites') by comparing the numbers of such diagnoses to the historically known numbers of Loxosceles spiders from the same areas in four western American states. The medical community from non-endemic Loxosceles areas often makes loxoscelism diagnoses solely on the basis of dermonecrotic lesions where Loxosceles spiders are rare or non-existent. If these diagnoses were correct then Loxosceles populations should be evident, specimens should readily be collected over the years and there should be a reasonable correlation between diagnoses and spider specimens. In 41 months of data collection, we were informed of 216 loxoscelism diagnoses from California, Oregon, Washington and Colorado. In contrast, from these four states, we can only find historical evidence of 35 brown recluse or Mediterranean recluse spiders. There is no consistency between localities of known Loxosceles populations and loxoscelism diagnoses. There are many conditions of diverse etiology that manifest in dermonecrosis. In the western United States, physician familiarity with these conditions will lead to more accurate diagnoses and subsequent proper remedy.
Rute M. Gonçalves-de-andrade - One of the best experts on this subject based on the ideXlab platform.
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Tetracycline Reduces Kidney Damage Induced by Loxosceles Spider Venom.
Toxins, 2017Co-Authors: Cinthya Kimori Okamoto, Carmen W. Van Den Berg, Rute M. Gonçalves-de-andrade, Mizuno Masashi, Denise V. TambourgiAbstract:Envenomation by Loxosceles spider can result in two clinical manifestations: cutaneous and systemic loxoscelism, the latter of which includes renal failure. Although incidence of renal failure is low, it is the main cause of death, occurring mainly in children. The sphingomyelinase D (SMase D) is the main component in Loxosceles spider venom responsible for local and systemic manifestations. This study aimed to investigate the toxicity of L. intermedia venom and SMase D on kidney cells, using both In vitro and in vivo models, and the possible involvement of endogenous metalloproteinases (MMP). Results demonstrated that venom and SMase D are able to cause death of human kidney cells by apoptosis, concomitant with activation and secretion of extracellular matrix metalloproteases, MMP-2 and MMP-9. Furthermore, cell death and MMP synthesis and secretion can be prevented by tetracycline. In a mouse model of systemic loxoscelism, Loxosceles venom-induced kidney failure was observed, which was abrogated by administration of tetracycline. These results indicate that MMPs may play an important role in Loxosceles venom-induced kidney injury and that tetracycline administration may be useful in the treatment of human systemic loxoscelism.
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Loxosceles niedeguidonae (Araneae, Sicariidae) a new species of brown spider from Brazilian semi-arid region
ZooKeys, 2012Co-Authors: Rute M. Gonçalves-de-andrade, Rogério Bertani, Roberto Hiroaki Nagahama, Maria Fatima Ribeiro BarbosaAbstract:A new species of recluse spider, Loxosceles niedeguidonae sp. n., is described from the Parque Nacional Serra da Capivara, State of Piaui, Brazil. This is the first endemic species described from Brazilian semiarid environment. The species is included in gaucho group of Gertsch (1967) due to its spermathecal shape and is considered close to L. chapadensis Bertani, Fukushima & Nagahama, 2010 by the unusual long male palpal tibia, a character not common for species of this group. An updated key for Loxosceles species of gaucho group is presented.
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Transcriptome analysis of Loxosceles laeta (Araneae, Sicariidae) spider venomous gland using expressed sequence tags
BMC genomics, 2008Co-Authors: Matheus F. Fernandes-pedrosa, Rute M. Gonçalves-de-andrade, Inácio L.m. Junqueira-de-azevedo, Leonardo S. Kobashi, Diego Dantas Almeida, Denise V. TambourgiAbstract:Background The bite of spiders belonging to the genus Loxosceles can induce a variety of clinical symptoms, including dermonecrosis, thrombosis, vascular leakage, haemolysis, and persistent inflammation. In order to examine the transcripts expressed in venom gland of Loxosceles laeta spider and to unveil the potential of its products on cellular structure and functional aspects, we generated 3,008 expressed sequence tags (ESTs) from a cDNA library.
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Tetracycline Protects against Dermonecrosis Induced by Loxosceles Spider Venom
The Journal of investigative dermatology, 2007Co-Authors: Danielle Paixao-cavalcante, Rute M. Gonçalves-de-andrade, Carmen W. Van Den Berg, Matheus F. Fernandes-pedrosa, Cinthya Kimori Okamoto, Denise V. TambourgiAbstract:Envenomation by spiders belonging to the Loxosceles genus (brown spider) often results in local dermonecrotic lesions. We have previously shown that Loxosceles sphingomyelinase D (SMase D), the venom component responsible for all the pathological effects, induced the expression of matrix metalloproteinases (MMPs) in rabbits and in human keratinocytic cells. We also showed that the SMase D-induced apoptosis and MMP expression of keratinocytes was inhibited by tetracyclines. We have further investigated the ability of tetracyclines to inhibit or prevent the dermonecrotic lesion induced by Loxosceles venom in vivo and in vitro models. Primary cultures of rabbit fibroblasts incubated with increasing concentrations of venom or SMase D showed a decrease in cell viability, which was prevented by tetracyclines. In vivo experiments showed that topical treatments with tetracycline of rabbits, inoculated with crude Loxosceles intermedia venom or recombinant SMase D, significantly reduced the progression of the dermonecrotic lesion. Furthermore, tetracyclines also reduced the expression of MMP-2 and prevented the induction of MMP-9. Our results suggest that tetracycline may be an effective therapeutic agent for the treatment of cutaneous loxoscelism.
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Loxosceles spider venom induces the release of thrombomodulin and endothelial protein C receptor: implications for the pathogenesis of intravascular coagulation as observed in loxoscelism
Journal of thrombosis and haemostasis : JTH, 2007Co-Authors: C W Van Den Berg, Fábio Carlos Magnoli, Rute M. Gonçalves-de-andrade, Denise V. TambourgiAbstract:Summary. Background: The venom of the spider Loxosceles can cause both local and systemic effects including disseminated intravascular coagulation. Aim: The aim of this study was to investigate the effects of the venom of Loxosceles intermedia (L. intermedia) and the purified Sphingomyelinase D (SMaseD) toxin upon the Protein C (PC) natural anticoagulant pathway. Results: Both the venom and e purified SMaseD reduced the cell surface expression of thrombomodulin (TM) and Endothelial PC Receptor on endothelial cells in culture. The reduction of cell surface expression was caused by cleavage from the cell surface mediated by activation of an endogenous metalloproteinase. Reduction of TM and Endothelial PC Receptor on the surface of these cells resulted in an impaired ability of the cells to assist in the thrombin-induced activation of PC. Conclusion: This novel observation gives further insight into the mechanisms of the pathology induced by venom from Loxosceles spiders and may aid the development of a suitable therapy.
Evanguedes Kalapothakis - One of the best experts on this subject based on the ideXlab platform.
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From taxonomy to molecular characterization of brown spider venom: An overview focused on Loxosceles similis.
Toxicon : official journal of the International Society on Toxinology, 2019Co-Authors: Bárbara Bruna Ribeiro De Oliveira-mendes, Clara Guerra-duarte, Maria Chatzaki, Douglas Ferreira Sales-medina, Hortênsia Gomes Leal, Ray Van Der Veer, Gabriela Lago Biscoto, Priscila Mendes Gonçalves, Thais Soares Da Silva, Evanguedes KalapothakisAbstract:Loxosceles spp. (Araneae, Sicariidae), known as brown spiders, are distributed in temperate and tropical regions worldwide. Accidents caused by these spiders are known as loxoscelism and constitute a public health problem, especially in Brazil. The present review describes the taxonomy, distribution, and ecological profile of brown spiders, as well as the molecular and biochemical aspects of Loxosceles venom. Additionally, it presents an overview on L. similis, a species found in the Southeastern region of Brazil. In this region, the number of Loxosceles accidents has been increasing in the past few years, thus calling attention to its raising importance as a medically relevant spider species in Brazil.
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Diversity of astacin-like metalloproteases identified by transcriptomic analysis in Peruvian Loxosceles laeta spider venom and in vitro activity characterization.
Biochimie, 2019Co-Authors: Raíssa Medina-santos, Evanguedes Kalapothakis, Fernanda Costal-oliveira, Sabrina De Almeida Lima, Clara Guerra-duarte, Priscilla Alves De Aquino, Anderson Oliveira Do Carmo, César Bonilla Ferreyra, Edgar Gonzalez-kozlova, Carlos Chávez-olórteguiAbstract:Abstract Loxosceles spiders are found in almost all countries of South America. In Peru, Loxosceles laeta species is the main responsible for the accidents caused by poisonous animals, being known as “killer spiders”, due to the large number of fatal accidents observed. Astacin-like metalloproteases, named LALPs (Loxosceles astacin-like metalloproteases) are highly expressed in Loxosceles spiders venom gland. These proteases may be involved in hemorrhage and venom spreading, being relevant to the envenoming proccess. Thus, the aim of this work was to analyze Peruvian L. laeta venom gland transcripts using bioinformatics tools, focusing on LALPs. A cDNA library from Peruvian L. laeta venom glands was constructed and sequenced by MiSeq (Illumina) sequencer. After assembly, the resulting sequences were annotated, seeking out for similarity with previously described LALPs. Nine possible LALPs isoforms from Peruvian L. laeta venom were identified and the results were validated by in silico and in vitro experiments. This study contributes to a better understanding of the molecular diversity of Loxosceles venom and provide insights about the action of LALPs.
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innovative immunization protocols using chimeric recombinant protein for the production of polyspecific loxoscelic antivenom in horses
Toxicon, 2014Co-Authors: Luis F M Figueiredo, João Carlos Minozzo, Evanguedes Kalapothakis, Camila Diaslopes, Larissa Magalhaes Alvarenga, T M Mendes, Ricardo A Machadodeavila, Jessica Mccormack, Carlos ChavezolorteguiAbstract:A chimeric protein (rCpLi) was constructed expressing three epitopes of rLiD1, a dermonecrotic toxin from the venom of Loxosceles intermedia spider. We have analyzed the neutralization potential of sera obtained by immunization of horses with rCpLi and rCpLi combined with initial doses of venoms and compared these with antivenom traditionally produced in horses using crude Loxosceles gaucho, Loxosceles laeta and L. intermedia venoms as antigens. We have demonstrated by ELISA that horses immunized with three initial doses of crude venom containing mixtures of L. intermedia, L. gaucho and L. laeta followed by nine doses of rCpLi generate antibodies with the same reactivity as those produced following immunization with traditional antivenom, towards the venoms of the three Loxosceles sp. species. Results from in vivo and in vitro neutralization assays showed that the new horse sera are able to neutralize the dermonecrotic activity of Loxosceles venoms, which are of medical importance in Brazil and some of these sera are capable of meeting the necessary potency requirements that could allow for their therapeutic use in humans. This immunization strategy combining both antigens used approximately 67% less crude Loxosceles venoms compared to traditional immunization protocol and can mean the development of Loxosceles antivenoms with the consequent reduction of devastation of arachnid fauna.
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Determination of sphingomyelinase-D activity of Loxosceles venoms in sphingomyelin/cholesterol liposomes containing horseradish peroxidase
Toxicon : official journal of the International Society on Toxinology, 2011Co-Authors: Marco Túlio R. Gomes, Olga Meiri Chaim, João Carlos Minozzo, Gabriela Guimarães, Frédéric Frézard, Evanguedes Kalapothakis, Silvio Sanches Veiga, Sergio Costa Oliveira, Carlos Chávez-olórteguiAbstract:Based on degradation of sphingomyelin/cholesterol liposomes containing entrapped horseradish peroxidase, we evaluated the Sphingomyelinase-D (SMase-D) activity of scorpion, spider and snake venoms by monitoring spectrophotometrically the product of oxidation of HRP released. The results indicate that Loxosceles crude venoms (Loxosceles intermedia, Loxosceles laeta, Loxosceles gaucho and Loxosceles similis) displayed SMase-D activity in a concentration-dependent manner. Furthermore, this activity was blocked by the anti-loxoscelic antivenom. However, Tityus serrulatus scorpion venom, Phoneutria nigriventer spider venom and Bothrops jararaca, Crotalus durissus, Lachesis muta and Micrurus frontalis snake venoms did not show measurable SMase-D activity.
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cardiotoxic effects of Loxosceles intermedia spider venom and the recombinant venom toxin rlid1
Toxicon, 2010Co-Authors: Gabriela Guimarães, Liza Felicori, Camila Diaslopes, Eneas R M Gomes, Danilo Romancampos, Hugo L Duarte, Denis D Damasceno, Marilia Martins, Evanguedes KalapothakisAbstract:Loxosceles spider bites cause many human injuries worldwide. Injections in mice of whole Loxosceles (L.) intermedia venom or a recombinant toxin (rLiD1) produce systemic symptoms similar to those detected in envenomed humans. This animal model was used to characterize the effects of Loxosceles intermedia venom in cardiac tissues. L. intermedia antigens were detected by ELISA in kidney, heart, lung and liver of experimentally envenomed mice. In addition, rLiD1 binding to cardiomyocytes was demonstrated by immunofluorescence and confocal microscopy. Furthermore, isolated perfused heart preparations and ventricular cardiomyocytes from envenomed mice showed heart function impairment, and a significant increase of ICa,L density and intracellular Ca2+ transients, respectively. Thus, L. intermedia spider venom, as shown through the use of the recombinant toxin rLiD1, causes cardiotoxic effects and a protein from the sphingomyelinase D family plays a key role in heart dysfunction. Thus, L. intermedia spider venom and the Loxtox rLiD1 play a key role in heart dysfunction.
