Publications by authors named "Carmen W van den Berg"

39 Publications

Sphingomyelinases D From Spider Venoms and Cell Membranes: Action on Lipid Rafts and Activation of Endogenous Metalloproteinases.

Front Pharmacol 2020 13;11:636. Epub 2020 May 13.

Laboratório de Imunoquímica, Instituto Butantan, São Paulo, Brazil.

spider venom contains Sphingomyelinase D (SMase D), the key toxin causing pathology. SMase D hydrolyzes the main component of lipid rafts, sphingomyelin, which changes the membrane microenvironment resulting in the activation of endogenous metalloproteinase from the ADAMs family. Alterations in membrane microenvironment of lipid rafts contribute to the activation of several cell surface molecules. Serine proteinases convertases acting on the pro-domain of membrane metalloproteinases, such as ADAMs, increase the cleavage and the release of proteins ectodomains and receptors located at the cell surface areas containing lipid rafts. We, therefore, investigated the interaction of SMases D with these membrane microdomains (lipid rafts) in human keratinocytes, to better understand the molecular mechanism of SMases D action, and identify the ADAM(s) responsible for the cleavage of cell surface molecules. Using specific inhibitors, we observed that ADAMs 10 and 17 are activated in the cell membrane after SMase D action. Furthermore, proproteins convertases, such as furin, are involved in the SMase D induced ADAMs activation. One of the signaling pathways that may be involved in the activation of these proteases is the MAPK pathway, since phosphorylation of ERK1/2 was observed in cells treated with SMase D. Confocal analysis showed a strong colocalization between SMase D and GM ganglioside present in rafts. Analysis of structural components of rafts, such as caveolin-1 and flotillin-1, showed that the action of SMase D on cell membranes leads to a reduction in caveolin-1, which is possibly degraded by toxin-induced superoxide production in cells. The action of the toxin also results in flotilin-1 increased detection in the cell membrane. These results indicate that SMases D from venoms alter membrane rafts structure, leading to the activation of membrane bound proteases, which may explain why the lipase action of this toxin can result in proteolytic cleavage of cell surface proteins, ultimately leading to pathology.
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http://dx.doi.org/10.3389/fphar.2020.00636DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7237637PMC
May 2020

Venom from , a Snake Species Native to Martinique, Potently Activates the Complement System.

J Immunol Res 2018 15;2018:3462136. Epub 2018 Jul 15.

Immunochemistry Laboratory, Butantan Institute, Av. Prof. Vital Brazil 1500, 05503-900 São Paulo, SP, Brazil.

snake venom causes systemic thrombotic syndrome but also local inflammation involving extensive oedema, pain, and haemorrhage. Systemic thrombotic syndrome may lead to fatal pulmonary embolism and myocardial and cerebral infarction. Here, we investigated the ability of venom to activate the Complement system (C) in order to improve the understanding of venom-induced local inflammation. Data presented show that venom is able to activate all C-pathways. In human serum, the venom strongly induced the generation of anaphylatoxins, such as C5a and C4a, and the Terminal Complement complex. The venom also induced cleavage of purified human components C3, C4, and C5, with the production of biologically active C5a. Furthermore, the venom enzymatically inactivated the soluble C-regulator and the C1-inhibitor (C1-INH), and significantly increased the expression of bound C-regulators, such as MCP and CD59, on the endothelial cell membrane. Our observations that venom activates the three Complement activation pathways, resulting in anaphylatoxins generation, may suggest that this could play an important role in local inflammatory reaction and systemic thrombosis caused by the venom. Inactivation of C1-INH, which is also an important inhibitor of several coagulation proteins, may also contribute to inflammation and thrombosis. Thus, further studies may support the idea that therapeutic management of systemic envenomation could include the use of Complement inhibitors as adjunct therapy.
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http://dx.doi.org/10.1155/2018/3462136DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6079423PMC
November 2018

Loxosceles venom Sphingomyelinase D activates human blood leukocytes: Role of the complement system.

Mol Immunol 2018 02 16;94:45-53. Epub 2017 Dec 16.

Immunochemistry Laboratory, Butantan Institute, Av. Vital Brazil, 1500, 05503-900, São Paulo, SP, Brazil. Electronic address:

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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http://dx.doi.org/10.1016/j.molimm.2017.12.009DOI Listing
February 2018

Tetracycline Reduces Kidney Damage Induced by Loxosceles Spider Venom.

Toxins (Basel) 2017 03 2;9(3). Epub 2017 Mar 2.

Immunochemistry Laboratory, Butantan Institute, São Paulo 05503-900, Brazil.

Envenomation by 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 spider venom responsible for local and systemic manifestations. This study aimed to investigate the toxicity of 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, venom-induced kidney failure was observed, which was abrogated by administration of tetracycline. These results indicate that MMPs may play an important role in venom-induced kidney injury and that tetracycline administration may be useful in the treatment of human systemic loxoscelism.
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http://dx.doi.org/10.3390/toxins9030090DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5371845PMC
March 2017

Sphingomyelinase D from Loxosceles laeta Venom Induces the Expression of MMP7 in Human Keratinocytes: Contribution to Dermonecrosis.

PLoS One 2016 14;11(4):e0153090. Epub 2016 Apr 14.

Immunochemistry Laboratory, Butantan Institute, São Paulo, Brazil.

Envenomation by Loxosceles spider is characterized by the development of dermonecrosis. In previous studies, we have demonstrated that increased expression/secretion of matrix metalloproteinases 2 and 9, induced by Loxosceles intermedia venom Class 2 SMases D (the main toxin in the spider venom), contribute to the development of cutaneous loxoscelism. In the present study we show that the more potent venom containing the Class 1 SMase D from Loxosceles laeta, in addition to increasing the expression/secretion of MMP2 and MMP9, also stimulates the expression of MMP7 (Matrilysin-1), which was associated with keratinocyte cell death. Tetracycline, a matrix metalloproteinase inhibitor, prevented cell death and reduced MMPs expression. Considering that L. laeta venom is more potent at inducing dermonecrosis than L. intermedia venom, our results suggest that MMP7 may play an important role in the severity of dermonecrosis induced by L. laeta spider venom SMase D. In addition, the inhibition of MMPs by e.g. tetracyclines may be considered for the treatment of the cutaneous loxoscelism.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0153090PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4831769PMC
August 2016

Characterization of a Gene Coding for the Complement System Component FB from Loxosceles laeta Spider Venom Glands.

PLoS One 2016 15;11(1):e0146992. Epub 2016 Jan 15.

Immunochemistry Laboratory, Butantan Institute, São Paulo, Brazil.

The human complement system is composed of more than 30 proteins and many of these have conserved domains that allow tracing the phylogenetic evolution. The complement system seems to be initiated with the appearance of C3 and factor B (FB), the only components found in some protostomes and cnidarians, suggesting that the alternative pathway is the most ancient. Here, we present the characterization of an arachnid homologue of the human complement component FB from the spider Loxosceles laeta. This homologue, named Lox-FB, was identified from a total RNA L. laeta spider venom gland library and was amplified using RACE-PCR techniques and specific primers. Analysis of the deduced amino acid sequence and the domain structure showed significant similarity to the vertebrate and invertebrate FB/C2 family proteins. Lox-FB has a classical domain organization composed of a control complement protein domain (CCP), a von Willebrand Factor domain (vWFA), and a serine protease domain (SP). The amino acids involved in Mg2+ metal ion dependent adhesion site (MIDAS) found in the vWFA domain in the vertebrate C2/FB proteins are well conserved; however, the classic catalytic triad present in the serine protease domain is not conserved in Lox-FB. Similarity and phylogenetic analyses indicated that Lox-FB shares a major identity (43%) and has a close evolutionary relationship with the third isoform of FB-like protein (FB-3) from the jumping spider Hasarius adansoni belonging to the Family Salcitidae.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0146992PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4714745PMC
July 2016

Microcirculation abnormalities provoked by Loxosceles spiders' envenomation.

Toxicon 2016 Jun 7;116:35-42. Epub 2015 Aug 7.

Immunochemistry Laboratory, Butantan Institute, São Paulo, Brazil. Electronic address:

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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http://dx.doi.org/10.1016/j.toxicon.2015.08.005DOI Listing
June 2016

A serine protease isolated from the bristles of the Amazonic caterpillar, Premolis semirufa, is a potent complement system activator.

PLoS One 2015 11;10(3):e0118615. Epub 2015 Mar 11.

Immunochemistry Laboratory, Butantan Institute, São Paulo, SP, Brazil.

Background: The caterpillar of the moth Premolis semirufa, commonly named pararama, is found in the Brazilian Amazon region. Accidental contact with the caterpillar bristles causes an intense itching sensation, followed by symptoms of an acute inflammation, which last for three to seven days after the first incident. After multiple accidents a chronic inflammatory reaction, called "Pararamose", characterized by articular synovial membrane thickening with joint deformities common to chronic synovitis, frequently occurs. Although complement mediated inflammation may aid the host defense, inappropriate or excessive activation of the complement system and generation of anaphylatoxins can lead to inflammatory disorder and pathologies. The aim of the present study was to evaluate, in vitro, whether the Premolis semirufa's bristles extract could interfere with the human complement system.

Results: The bristles extract was able to inhibit the haemolytic activity of the alternative pathway, as well as the activation of the lectin pathway, but had no effect on the classical pathway, and this inhibition seemed to be caused by activation and consumption of complement components. The extract induced the production of significant amounts of all three anaphylatoxins, C3a, C4a and C5a, promoted direct cleavage of C3, C4 and C5 and induced a significant generation of terminal complement complexes in normal human serum. By using molecular exclusion chromatography, a serine protease of 82 kDa, which activates complement, was isolated from P. semirufa bristles extract. The protease, named here as Ps82, reduced the haemolytic activity of the alternative and classical pathways and inhibited the lectin pathway. In addition, Ps82 induced the cleavage of C3, C4 and C5 and the generation of C3a and C4a in normal human serum and it was capable to cleave human purified C5 and generate C5a. The use of Phenanthroline, metalloprotease inhibitor, in the reactions did not significantly interfere with the activity of the Ps82, whereas the presence of PMSF, serine protease inhibitor, totally blocked the activity.

Conclusion: These data show that a serine protease present in the Premolis semirufa's bristles extract has the ability to activate the complement system, which may contribute to the inflammatory process presented in humans after envenomation.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0118615PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4356561PMC
December 2015

Animal venoms/toxins and the complement system.

Mol Immunol 2014 Oct 3;61(2):153-62. Epub 2014 Jul 3.

Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Cardiff, UK. Electronic address:

Nature is a wealthy source of agents that have been shown to be beneficial to human health, but nature is also a rich source of potential dangerous health damaging compounds. This review will summarise and discuss the agents from the animal kingdom that have been shown to interact with the human complement (C) system. Most of these agents are toxins found in animal venoms and animal secretions. In addition to the mechanism of action of these toxins, their contribution to the field of complement, their role in human pathology and the potential benefit to the venomous animal itself will be discussed. Potential therapeutic applications will also be discussed.
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http://dx.doi.org/10.1016/j.molimm.2014.06.020DOI Listing
October 2014

Mechanism of neutrophil dysfunction: neutrophil serine proteases cleave and inactivate the C5a receptor.

J Immunol 2014 Feb 20;192(4):1787-95. Epub 2014 Jan 20.

Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Cardiff CF14 4XN, United Kingdom;

Neutrophil dysfunction, resulting in inefficient bacterial clearance, is a feature of several serious medical conditions, including cystic fibrosis (CF) and sepsis. Poorly controlled neutrophil serine protease (NSP) activity and complement activation have been implicated in this phenomenon. The capacity for excess NSP secretion and complement activation to influence the expression and function of the important neutrophil-activating receptor C5aR was investigated. Purified NSPs cathepsin G (CG), neutrophil elastase (NE), and proteinase 3 cleaved C5aR to a 26- to 27-kDa membrane-bound fragment, thereby inactivating its C5a-induced signaling ability. In a supernatant transfer assay, NSPs released from neutrophils in response to C5a induced the cleavage of the C5aR on unstimulated cells. Stimulation of myeolomonocytic U937 cells and purified neutrophils with C5a resulted in downregulation of the C5aR on these cells, which, in the case of U937 cells, was largely caused by NSP-mediated cleavage of C5aR, but in the case of neutrophils, intracellular degradation was likely the main mediator in addition to a small role for NSPs. CG and NE in bronchoalveolar lavage fluid from CF patients both contributed to C5aR cleavage. We propose two converging models for C5a- and NSP-mediated neutrophil dysfunction whereby C5aR cleavage is induced by NSPs, secreted in response to: 1) excess C5a generation or other stimuli; or 2) necrosis. The consequent impairment of C5aR activity contributes to suboptimal local neutrophil priming and bacterial clearance. NSP inhibitors with specificity for both CG and NE may aid the treatment of pathologies associated with neutrophil dysfunction including sepsis and CF.
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http://dx.doi.org/10.4049/jimmunol.1301920DOI Listing
February 2014

P-I snake venom metalloproteinase is able to activate the complement system by direct cleavage of central components of the cascade.

PLoS Negl Trop Dis 2013 31;7(10):e2519. Epub 2013 Oct 31.

Laboratório de Imunoquímica, Instituto Butantan, São Paulo, Brazil.

Background: Snake Venom Metalloproteinases (SVMPs) are amongst the key enzymes that contribute to the high toxicity of snake venom. We have recently shown that snake venoms from the Bothrops genus activate the Complement system (C) by promoting direct cleavage of C-components and generating anaphylatoxins, thereby contributing to the pathology and spread of the venom. The aim of the present study was to isolate and characterize the C-activating protease from Bothrops pirajai venom.

Results: Using two gel-filtration chromatography steps, a metalloproteinase of 23 kDa that activates Complement was isolated from Bothrops pirajai venom. The mass spectrometric identification of this protein, named here as C-SVMP, revealed peptides that matched sequences from the P-I class of SVMPs. C-SVMP activated the alternative, classical and lectin C-pathways by cleaving the α-chain of C3, C4 and C5, thereby generating anaphylatoxins C3a, C4a and C5a. In vivo, C-SVMP induced consumption of murine complement components, most likely by activation of the pathways and/or by direct cleavage of C3, leading to a reduction of serum lytic activity.

Conclusion: We show here that a P-I metalloproteinase from Bothrops pirajai snake venom activated the Complement system by direct cleavage of the central C-components, i.e., C3, C4 and C5, thereby generating biologically active fragments, such as anaphylatoxins, and by cleaving the C1-Inhibitor, which may affect Complement activation control. These results suggest that direct complement activation by SVMPs may play a role in the progression of symptoms that follow envenomation.
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http://dx.doi.org/10.1371/journal.pntd.0002519DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3814341PMC
June 2014

Venom of the Brazilian spider Sicarius ornatus (Araneae, Sicariidae) contains active sphingomyelinase D: potential for toxicity after envenomation.

PLoS Negl Trop Dis 2013 22;7(8):e2394. Epub 2013 Aug 22.

Immunochemistry Laboratory, Butantan Institute, São Paulo, Brazil.

Background: The spider family Sicariidae includes two genera, Sicarius and Loxosceles. Bites by Sicarius are uncommon in humans and, in Brazil, a single report is known of a 17-year old man bitten by a Sicarius species that developed a necrotic lesion similar to that caused by Loxosceles. Envenomation by Loxosceles spiders can result in dermonecrosis and severe ulceration. Sicarius and Loxosceles spider venoms share a common characteristic, i.e., the presence of Sphingomyelinases D (SMase D). We have previously shown that Loxosceles SMase D is the enzyme responsible for the main pathological effects of the venom. Recently, it was demonstrated that Sicarius species from Africa, like Loxosceles spiders from the Americas, present high venom SMase D activity. However, despite the presence of SMase D like proteins in venoms of several New World Sicarius species, they had reduced or no detectable SMase D activity. In order to contribute to a better understanding about the toxicity of New World Sicarius venoms, the aim of this study was to characterize the toxic properties of male and female venoms from the Brazilian Sicarius ornatus spider and compare these with venoms from Loxosceles species of medical importance in Brazil.

Methodology/principal Findings: SDS-PAGE analysis showed variations in the composition of Loxosceles spp. and Sicarius ornatus venoms. Differences in the electrophoretic profiles of male and female venoms were also observed, indicating a possible intraspecific variation in the composition of the venom of Sicarius spider. The major component in all tested venoms had a Mr of 32-35 kDa, which was recognized by antiserum raised against Loxosceles SMases D. Moreover, male and female Sicarius ornatus spiders' venoms were able to hydrolyze sphingomyelin, thus showing an enzymatic activity similar to that determined for Loxosceles venoms. Sicarius ornatus venoms, as well as Loxosceles venoms, were able to render erythrocytes susceptible to lysis by autologous serum and to induce a significant loss of human keratinocyte cell viability; the female Sicarius ornatus venom was more efficient than male.

Conclusion: We show here, for the first time, that the Brazilian Sicarius ornatus spider contains active Sphingomyelinase D and is able to cause haemolysis and keratinocyte cell death similar to the South American Loxosceles species, harmful effects that are associated with the presence of active SMases D. These results may suggest that envenomation by this Sicarius spider has the potential to cause similar pathological events as that caused by Loxosceles envenomation. Our results also suggest that, in addition to the interspecific differences, intraspecific variations in the venoms composition may play a role in the toxic potential of the New World Sicarius venoms species.
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http://dx.doi.org/10.1371/journal.pntd.0002394DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3749972PMC
February 2014

Roles of promoter and 3' untranslated motifs in expression of the human C5a receptor.

Mol Immunol 2012 Sep 17;52(2):88-95. Epub 2012 May 17.

Institute of Molecular and Experimental Medicine, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK.

The C5a receptor (C5aR) is a 7 transmembrane G-protein coupled receptor (GPCR) that mediates the powerful pro-inflammatory effect of the complement activation product C5a. Excess C5a generated under pathological conditions has been implicated in a variety of conditions including sepsis, asthma and rheumatoid arthritis, but very little is known about the regulation of expression of the C5aR. The 5' promoter region and 3' untranslated region (UTR) of the C5aR mRNA were cloned, generating enhanced green fluorescent protein (EGFP)-reporter plasmids, which were transfected into the monocytic cell line U937. Most of the cloned 2kb 5' region was dispensable for the expression of the reporter constructs and the majority of regulatory sequences are in the first 200 bp. Three motifs, a NFκB, a CCAAT and a NFAT site, were identified to be of importance by site directed mutagenesis for basal expression. Analysis of the 3'UTR of the C5aR mRNA showed that it contained two AU-rich elements (AREs), however site directed mutagenesis showed that these had no effect on basal expression. While the phorbol ester PMA and dibutyryl cAMP increased C5aR protein expression, these agents had no effect on the regulation of expression via the promoter or the 3'UTR. This is the first study to investigate the role of both the promoter and 3'UTR in regulating C5aR expression and our results show that regulation of the human C5aR is similar but not identical to that of the mouse C5aR.
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http://dx.doi.org/10.1016/j.molimm.2012.04.012DOI Listing
September 2012

Premolis semirufa (Walker, 1856) envenomation, disease affecting rubber tappers of the Amazon: searching for caterpillar-bristles toxic components.

PLoS Negl Trop Dis 2012 28;6(2):e1531. Epub 2012 Feb 28.

Immunochemistry Laboratory, Butantan Institute, São Paulo, São Paulo, Brazil.

Background: The caterpillar of the moth Premolis semirufa (Lepidoptera: Arctiidae), commonly named Pararama, is endemic of the Amazon basin. Accidental contact with these caterpillar bristles causes local symptoms such as intense heat, pain, edema and itching which last for three to seven days; however, after multiples contacts, it may induce joint-space narrowing and bone alteration, as well as degeneration of the articular cartilage and immobilization of the affected joints. Specific treatment for this disease does not exist, but corticosteroids are frequently administered. Despite of the public health hazard of Premolis semirufa caterpillar poisoning, little is known about the nature of the toxic components involved in the induction of the pathology.

Methodology/principal Findings: Here we have investigated the biological and immunochemical characteristics of the caterpillar's bristles components. Analysis of the bristles extract in in vitro assays revealed the presence of proteolytic and hyaluronidase activities but no phospholipase A(2) activity. In vivo, it was observed that the bristles extract is not lethal but can induce an intense inflammatory process, characterized by the presence of neutrophils in the paw tissues of injected mice. Furthermore, the bristles components stimulated an intense and specific antibody response but autoantibodies such as anti-DNA or anti-collagen type II were not detected.

Conclusion: The results suggest that Premolis semirufa caterpillar bristles secretion contains a mixture of different enzymes that may act together in the generation and development of the clinical manifestations of the Pararama envenomation. Moreover, the high immunogenicity of the caterpillar bristles components, as shown by the generation of high antibody titers, may also contribute to the induction and establishment of the inflammatory disease.
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http://dx.doi.org/10.1371/journal.pntd.0001531DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3289609PMC
June 2012

C5a receptor is cleaved by metalloproteases induced by sphingomyelinase D from Loxosceles spider venom.

Immunobiology 2012 Sep 10;217(9):935-41. Epub 2012 Jan 10.

Department of Pharmacology, Oncology and Radiology, School of Medicine, Cardiff University, Cardiff, UK.

Neutrophils are involved in numerous pathologies and are considered to be major contributors to the establishment of cutaneous loxoscelism after envenomation by the Loxosceles spider. Neutrophils are attracted to the site of envenomation by locally generated C5a and contribute to the tissue destruction. We have investigated the effects of this spider venom on the receptor for C5a: C5aR/CD88, a seven transmembrane G-protein coupled receptor. We show here that the Loxosceles venom induces the cleavage of the C5aR at two sites, resulting in the release of the extracellular N-terminus, while retaining part of the transmembrane regions. Using specific inhibitors, it was shown that the cleavage was induced by activation of an endogenous metalloprotease of the adamalysin (ADAM) family, which was activated by the sphingomyelinase D in the venom. Although it resulted in the near complete loss of the N-terminus, C5a was still able to induce a small increase in intracellular calcium and increase secretion of IL-8. The cleavage of the C5aR may well be a protective response after envenomation, rather than contributing to the pathology of Loxosceles envenomation and may represent a general mechanism for how the body protects itself against excess C5a generation in pathological circumstances such as sepsis.
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http://dx.doi.org/10.1016/j.imbio.2012.01.005DOI Listing
September 2012

Binding of human antigen R (HuR) to an AU-rich element (ARE) in the 3'untranslated region (3'UTR) reduces the expression of decay accelerating factor (DAF).

Mol Immunol 2010 Oct 9;47(16):2545-51. Epub 2010 Aug 9.

Department of Pharmacology, Oncology & Radiology, School of Medicine, Cardiff University, Heath Park, Cardiff CF14 4XN, UK.

We have investigated the role of the 3'untranslated region (3'UTR) in the expression of decay accelerating factor (DAF), one of the major membrane regulators of Complement activation. We show here that the 3'UTR of DAF contains an adenylate uridine rich element (ARE) AUUUAUUUAUAUUUAUUUA, which belongs to Class II Cluster 4 of the AU-rich element-containing mRNA (ARED) database. Enhanced Green Fluorescent Protein (EGFP) Reporter constructs containing the DAF 3'UTR showed reduced levels of expression when transfected into a variety of cell lines compared to 3'UTR reporter constructs without the ARE sequence. Furthermore, the inhibitor of mRNA transcription Actinomycin D had a much stronger effect on mRNA half-life of the ARE-containing 3'UTR demonstrating that this ARE destabilises the mRNA. Electrophoretic Mobility Shift Assays (EMSA) using biotinylated RNA probes, demonstrated that cytoplasmic Human antigen R (HuR) bound to the DAF ARE. Transfection experiments using HuR specific siRNA increased DAF expression whilst plasmids containing the coding sequence of HuR had the opposite effect, demonstrating that HuR reduced the stability of DAF mRNA and suggesting that it is of importance in regulating the expression of DAF. These data suggest that modulators of HuR could potentially be used to alter DAF expression and therefore increase the susceptibility of malignant cells to immunotherapy.
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http://dx.doi.org/10.1016/j.molimm.2010.07.002DOI Listing
October 2010

Human complement activation and anaphylatoxins generation induced by snake venom toxins from Bothrops genus.

Mol Immunol 2010 Oct 31;47(16):2537-44. Epub 2010 Jul 31.

Immunochemistry Laboratory, Butantan Institute, Av. Prof. Vital Brazil, 1500, CEP 05503-900, São Paulo, Brazil.

Snake venoms are a complex mixture of components, which have a wide range of actions both on prey and human victims. The genus Bothrops causes the vast majority of snakebites in Central and South America, being responsible for 80% of snake envenomations in Brazil. Envenomations are characterized by prominent local effects, including oedema, haemorrhage and necrosis, which can lead to permanent disability. Systemic manifestations such as haemorrhage, coagulopathy, shock and acute renal failure may also occur. In the present study we have investigated the action of venoms from 19 species of snakes from the genus Bothrops, occurring in Brazil, on the complement system in in vitro studies. All venoms were able to activate the classical complement pathway, in the absence of sensitizing antibody. This activation was in part associated with the cleavage of C1-Inhibitor by proteases present in these venoms, which disrupts complement activation control. No modification of the membrane bound complement regulators, such as DAF, CR1 and CD59 was detected, after treatment of human erythrocytes with the snake venoms. Some of the Bothrops venoms were also able to activate alternative and lectin pathways, as measured in haemolytic and ELISA assays. C3a, C4a and C5a were generated in sera treated with the venoms, not only through C-activation, but also by the direct cleavage of complement components, as determined using purified C3 and C4. Metallo- and/or serine-protease inhibitors prevented cleavage of C3 and C4. These results suggest that Bothrops venoms can activate the complement system, generating a large amount of anaphylatoxins, which may play an important role in the inflammatory process presented in humans after snake envenomations, and they may also assist, due to their vasodilatory effects, to enhance the spreading of other venom components.
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http://dx.doi.org/10.1016/j.molimm.2010.07.003DOI Listing
October 2010

Loxoscelism: From basic research to the proposal of new therapies.

Toxicon 2010 Dec 6;56(7):1113-9. Epub 2010 Feb 6.

Immunochemistry Laboratory, Butantan Institute, São Paulo, Brazil.

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, such as intravascular haemolysis, intravascular coagulation and renal failure. Current therapies are not effective, often not based in scientific research and can be even detrimental. A lack of understanding of the mechanism of action of the venom of the Loxosceles spider had thus far prevented development of effective therapies. In this review we aim to give an overview of our contributions to the understanding of the mechanism of action of the Loxosceles venom and propose targets and therapeutics for medical intervention.
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http://dx.doi.org/10.1016/j.toxicon.2010.01.021DOI Listing
December 2010

SMase II, a new sphingomyelinase D from Loxosceles laeta venom gland: molecular cloning, expression, function and structural analysis.

Toxicon 2009 Jun 26;53(7-8):743-53. Epub 2009 Feb 26.

Laboratório de Imunoquímica, Instituto Butantan, São Paulo, Brazil.

Sphingomyelinase D (SMase D) present in the venoms of Loxosceles spiders is the principal component responsible for local and systemic effects observed in the loxoscelism. By using "expressed sequencing tag", it was possible to identify, in a L. laeta venom gland library, clones containing inserts coding for proteins with similarity to SMase D. One of these clones was expressed and the recombinant protein compared with the previously characterized SMase I from L. laeta, in terms of their biological, biochemical and structural properties. The new recombinant protein, SMase II, possesses all the biological properties ascribed to the whole venom and SMase I. SMase II shares 40% and 77% sequence similarity with SMase I and Lb3, respectively; the latter, a SMase D isoform from L. boneti, catalytically inactive. Molecular modeling and molecular dynamics simulations were employed to understand the structural basis, especially the presence of an additional disulfide bridge, in an attempt to account for the observed differences in SMases D activity.
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http://dx.doi.org/10.1016/j.toxicon.2009.02.013DOI Listing
June 2009

Complement factor H binds to denatured rather than to native pentameric C-reactive protein.

J Biol Chem 2008 Nov 11;283(45):30451-60. Epub 2008 Sep 11.

Department of Medical Biochemistry and Immunology and Pharmacology, School of Medicine, Cardiff University, Cardiff CF14 4XN, UK.

Binding of the complement regulatory protein, factor H, to C-reactive protein has been reported and implicated as the biological basis for association of the H402 polymorphic variant of factor H with macular degeneration. Published studies utilize solid-phase or fluid-phase binding assays to show that the factor H Y402 variant binds C-reactive protein more strongly than H402. Diminished binding of H402 variant to C-reactive protein in retinal drusen is posited to permit increased complement activation, driving inflammation and pathology. We used well validated native human C-reactive protein and pure factor H Y402H variants to test interactions. When factor H variants were incubated with C-reactive protein in the fluid phase at physiological concentrations, no association occurred. When C-reactive protein was immobilized on plastic, either non-specifically by adsorption in the presence of Ca(2+) to maintain its native fold and pentameric subunit assembly or by specific Ca(2+)-dependent binding to immobilized natural ligands, no specific binding of either factor H variant from the fluid phase was observed. In contrast, both factor H variants reproducibly bound to C-reactive protein immobilized in the absence of Ca(2+), conditions that destabilize the native fold and pentameric assembly. Both factor H variants strongly bound C-reactive protein that was denatured by heat treatment before immobilization, confirming interaction with denatured but not native C-reactive protein. We conclude that the reported binding of factor H to C-reactive protein results from denaturation of the C-reactive protein during immobilization. Differential binding to C-reactive protein, thus, does not explain association of the Y402H polymorphism with macular degeneration.
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http://dx.doi.org/10.1074/jbc.M803648200DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2662140PMC
November 2008

Modulation of CD59 expression by restrictive silencer factor-derived peptides in cancer immunotherapy for neuroblastoma.

Cancer Res 2008 Jul;68(14):5979-87

Department of Medical Biochemistry and Immunology, School of Medicine, Cardiff University, Cardiff, United Kingdom.

Tumor cells escape clearance by complement by abundantly expressing CD59 and other membrane complement regulators. Existing strategies for blocking/knocking down these regulators can contribute to tumor immunoclearance in vitro; however, there are numerous difficulties restricting their use in vivo. Here, we report a new strategy for suppression of CD59 expression in neuroblastoma using peptides that target regulators of CD59 expression. We identified the neural-restrictive silencer factor (REST) as a target for modulation of CD59 expression in neuroblastoma. We next designed plasmids that encoded peptides comprising different DNA-binding domains of REST and transfected them into neuroblastoma cell lines. These peptides suppressed CD59 expression, sensitizing neuroblastoma to complement-mediated killing triggered by anti-GD2 therapeutic monoclonal antibody. These CD59-modulating peptides might be effective therapeutic adjuvants to therapeutic monoclonal antibodies used for treatment of neuroblastoma and other cancer types sharing the same mechanism for regulation of CD59 expression.
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http://dx.doi.org/10.1158/0008-5472.CAN-07-6828DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2475646PMC
July 2008

Tetracycline protects against dermonecrosis induced by Loxosceles spider venom.

J Invest Dermatol 2007 Jun 11;127(6):1410-8. Epub 2007 Jan 11.

Laboratório de Imunoquímica, Instituto Butantan, São Paulo, Brazil.

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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http://dx.doi.org/10.1038/sj.jid.5700688DOI Listing
June 2007

Structural and functional comparison of native pentameric, denatured monomeric and biotinylated C-reactive protein.

Immunology 2007 Mar 8;120(3):404-11. Epub 2006 Dec 8.

Department of Pharmacology, Therapeutics and Toxicology, Cardiff University, Wales College of Medicine, Cardiff, UK.

There are many controversies surrounding the biological activities of native C-reactive protein (nCRP) and its various modified forms such as monomerized and biotinylated CRP (mCRP and bCRP). No simple methods have been described to distinguish among these forms. By adapting established electrophoresis methods, we have developed a useful quality control method with which we have investigated the structural and functional characteristics of these forms of CRP. Under all electrophoresis conditions, biotinylation altered the electrophoretic mobility of CRP. nCRP was sensitive to sodium dodecyl sulphate (SDS)-induced monomerization, and only mCRP was susceptible to digestion by trypsin or neutrophil-derived serine proteases. bCRP and mCRP but not nCRP bound to cells, suggesting that chemical modification by biotin and denaturation had altered the structural integrity of CRP. Neither nCRP nor mCRP had the ability to induce secretion of chemokines, nor did they increase intracellular adhesion molecule 1 (ICAM-1) expression in endothelial cells.
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http://dx.doi.org/10.1111/j.1365-2567.2006.02516.xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2265887PMC
March 2007

Characterisation of the complement susceptibility of the rat aortic smooth muscle cell line A7r5.

Mol Immunol 2007 Jan 6;44(4):608-14. Epub 2006 Mar 6.

Department of Pharmacology, Therapeutics and Toxicology, Wales Heart Research Institute, Cardiff University, Wales College of Medicine, Heath Park, Cardiff CF144XN, United Kingdom.

Complement (C) activation is thought to contribute to the initiation and progression of atherosclerosis. Proliferation of smooth muscle cells plays an important role in atherosclerotic plaque formation. Our aim was to investigate the suitability of the rat aortic smooth muscle cell line A7r5 as an in vitro model to study C-induced events in smooth muscle cells. A7r5 cells abundantly expressed membrane bound C-regulators (CReg) Crry and CD59 as assessed by flow-cytometry, but no DAF or MCP was detected. Using RT-PCR in addition to Crry and CD59, also mRNA for rat DAF but not for MCP was detected. Flow-cytometry of cells removed by EDTA instead of trypsin demonstrated that A7r5 did express cell surface DAF. Upon prolonged culturing under either logarithmic growing conditions or under conditions where cells were kept over-confluent, two different sub cell lines were obtained, one which had lost the expression of CD59, while the other showed increased expression of DAF and Crry. The change in expression of these CReg resulted in a change in C-susceptibility. Incubation of the A7r5 cells with human serum induced membrane attack complex dependent proliferation. Transfection with human CD59 efficiently protected the cells from C-mediated killing and C-induced cell proliferation. Our results show that A7r5 cells can be used as an in vitro model for C-induced events, but care has to be taken to use the cells at an early stage of passaging as they readily change their phenotype.
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http://dx.doi.org/10.1016/j.molimm.2006.01.014DOI Listing
January 2007

Role of matrix metalloproteinases in HaCaT keratinocytes apoptosis induced by loxosceles venom sphingomyelinase D.

J Invest Dermatol 2006 Jan;126(1):61-8

Laboratório de Imunoquímica, Instituto Butantan, São Paulo, Brazil.

Envenomation by the spider Loxosceles (brown spider) can result in dermonecrosis and severe ulceration. We have previously shown that Loxosceles sphingomyelinase D (SMaseD), the enzyme responsible for these pathological effects, induced expression of matrix metalloproteinase-9 (MMP-9), which is possibly one of the main factors involved in the pathogenesis of the cutaneous loxoscelism. The aim of this study was to further investigate the molecular mechanisms triggered by Loxosceles SMaseD involved in the initiation of the dermonecrotic lesion, using HaCaT cultures, a human keratinocyte cell line, as an in vitro model for cutaneous loxoscelism. We show here that SMaseD from Loxosceles spider venom induces apoptosis in human keratinocytes, which is associated with an increased expression of metalloproteinase-2 and -9, and that the use of metalloproteinase inhibitors, such as tetracycline, may prevent cell death and potentially may prevent tissue destruction after envenomation.
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http://dx.doi.org/10.1038/sj.jid.5700049DOI Listing
January 2006

Loxosceles sphingomyelinase induces complement-dependent dermonecrosis, neutrophil infiltration, and endogenous gelatinase expression.

J Invest Dermatol 2005 Apr;124(4):725-31

Laboratório de Imunoquímica, Instituto Butantan, São Paulo, Brazil.

Envenomation by the spider Loxosceles can result in dermonecrosis and severe ulceration. Our aim was to investigate the role of the complement system and of the endogenous metalloproteinases in the initiation of the pathology of dermonecrosis. Histological analysis of skin of rabbits injected with Loxosceles intermedia venom and purified or recombinant sphingomyelinases showed a large influx of neutrophils, concomitant with dissociation of the collagenous fibers in the dermis. Decomplementation, using cobra venom factor, largely prevented the influx of neutrophils, while influx of neutrophils was also reduced in genetically C6-deficient rabbits, suggesting roles for both C5a and the membrane attack complex in the induction of dermonecrosis. However, C-depletion and C6 deficiency did not prevent the haemorrhage and the collagen injury. Zymography analysis of skin extracts showed the induction of expression of the endogenous gelatinase MMP-9 in the skin of envenomated animals. Rabbit neutrophils contained high levels of MMP-9, expression of which was further increased after incubation with venom, suggesting that these cells may be a source of the MMP-9 found in the skin of envenomated animals. Furthermore, skin fibroblasts also secreted MMP-9 and MMP-2 upon incubation with venom, suggesting that locally produced MMPs can also contribute to proteolytic tissue destruction.
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http://dx.doi.org/10.1111/j.0022-202X.2005.23654.xDOI Listing
April 2005

Porcine complement regulators protect aortic smooth muscle cells poorly against human complement-induced lysis and proliferation: consequences for xenotransplantation.

Xenotransplantation 2005 May;12(3):217-26

Department of Pharmacology, Therapeutics and Toxicology, Wales Heart Research Institute, Cardiff University, Wales College of Medicine, Cardiff, CF144XN, UK.

Background: Accelerated atherosclerosis after transplantation has been observed and is characterized by smooth muscle cell proliferation in the graft. Porcine cells are frequently used in models of atherosclerosis and porcine organs are considered for use in transplantation. Complement (C) activation is known to play a major role in rejection of xenografts and is also considered to play a role in the development of atherosclerosis. The aim of this study was to investigate the expression and function of membrane bound regulators of complement (CReg) on porcine aortic smooth muscle cells (PASMC).

Methods: The PASMC were assessed for expression of CReg and susceptibility to lysis by human C by flow-cytometry. The effect of various cytokines on CReg expression and C-susceptibility was investigated. The ability of human C to induce cell proliferation was assessed using the Alamar blue assay.

Results: The PASMC only express the CReg membrane cofactor protein (MCP) and CD59 on their cell surface. MCP expression was increased by interleukin (IL)-4. In contrast to porcine aortic endothelial cells (PAEC), PASMC were found to be surprisingly sensitive to C-mediated lysis, mainly due to a low level of expression of CD59. Human C-induced proliferation of PASMC, which was dependent on complete membrane attack complex (MAC) formation.

Conclusions: Endogenously expressed CReg on PASMC poorly protect these cells to human C. Human C can induce proliferation of PASMC. In order to prevent accelerated atherosclerosis in porcine xenografts, increased levels of CReg not only have to be obtained on the endothelial cells but also on the smooth muscle cells.
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http://dx.doi.org/10.1111/j.1399-3089.2005.00217.xDOI Listing
May 2005

C-reactive protein-induced in vitro endothelial cell activation is an artefact caused by azide and lipopolysaccharide.

Arterioscler Thromb Vasc Biol 2005 Jun 31;25(6):1225-30. Epub 2005 Mar 31.

Department of Pharmacology, Therapeutics and Toxicology, Cardiff University, Wales College of Medicine, Cardiff, UK.

Objective: C-reactive protein (CRP) has been proposed to be an independent risk factor for cardiovascular disease. In vitro studies investigating the mechanism behind this have used purified commercial CRP (cCRP) and endothelial cells. We investigated the role of contaminants in cCRP preparations.

Methods And Results: Human umbilical vein endothelial cells and the human endothelial cell line EA.hy926 were incubated with Escherichia coli-derived cCRP, in-house-generated azide-free recombinant, and ascites-purified CRP, azide, or lipopolysaccharide (LPS) equivalent to the concentration present in cCRP preparations. Cells were investigated for change in cell proliferation, morphology, apoptosis, and expression of endothelial NO synthase and intercellular adhesion molecule-1. Cell supernatants were assessed for monocyte chemoattractant protein-1 (MCP-1), interleukin-8, von Willebrand factor secretion, and pH change. Only cCRP was able to induce all activation events analyzed; however, this ability was lost on extensive dialysis, suggesting that low molecular weight contaminants were responsible for these events. Indeed, the effects of cCRP were mirrored by azide or LPS.

Conclusions: We investigated a wide range of effects on endothelial cells ascribed to CRP; however, azide and LPS, but never CRP itself, were responsible for the cell activation events. We conclude that CRP, per se, does not activate endothelial cells.
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http://dx.doi.org/10.1161/01.ATV.0000164623.41250.28DOI Listing
June 2005