Lonomia genus caterpillar toxins: biochemical aspects

Hemorrhagic erucism due to Lonomia spp. in Peru - A call for action

Envenomation due to exposure to caterpillars is an emerging public health problem. A life-threatening bleeding diathesis has been described in South America after exposure to Lonomia obliqua or L. acheolus. Deforestation, forest degradation, and global warming might increase the frequency of human exposure to these insects. Prompt recognition and administration of antivenom are crucial to ensure a favorable outcome.

Contribution of international cooperation in the management of the first documented case of Lonomia caterpillar envenoming (Lonomism) in Guyana

Severe Lonomia caterpillar envenoming is an increasing hazard in South America. It can trigger severe coagulation disorders that can progress to systemic complications and death. We report the first documented case of severe Lonomia caterpillar envenoming in Guyana. It was managed using antivenom provided by the Brazilian Ministry of Health as part of humanitarian support. This case describes a successful international collaboration driving a favorable outcome for the envenomed patient.

Biological characterization of bristle extract of Lonomia descimoni caterpillar (Lepidoptera, Saturniidae) and effectiveness of Lonomia antivenom to neutralize experimental envenomation in rats

Contact with Lonomia caterpillars can cause severe envenomation with hemorrhagic syndrome, consumptive coagulopathy, acute renal failure, and death. In Brazil, an antivenom was produced using extracts from L. obliqua caterpillar bristles as antigen and has been used in other countries in South America to treat envenomation caused by distinct species of Lonomia. This study aimed to characterize the activities of toxins from Lonomia descimoni caterpillars found in Colombia and the neutralization of these toxins by the Brazilian Lonomia antivenom. The protein composition and coagulant, phospholipase A₂, hyaluronidase, and defibrinogenating activities were evaluated and compared with the same parameters of the L. obliqua bristle extract. Immune recognition and the neutralizing ability of Lonomia antivenom were also determined. The results showed that the L. descimoni bristle extract presented marked differences in electrophoretic and mass spectrometry profiles and had coagulant, phospholipase A₂, and hyaluronidase activities significantly less intense than those of the L. obliqua extract. In rats, L. descimoni extract induced coagulopathy and hemoglobinuria when injected by intravenous or intraperitoneal routes. The Lonomia antivenom recognized the toxins in the extract of L. descimoni and reversed the experimental envenomation in rats. Our results indicate that L. descimoni caterpillars possess toxins with weaker activities than those of L. obliqua but with the potential to cause envenomation. Moreover, the Lonomia antivenom recognized and neutralized the toxins in the L. descimoni bristle extract.

Deadly and venomous Lonomia caterpillars are more than the two usual suspects

Caterpillars of the Neotropical genus Lonomia (Lepidoptera: Saturniidae) are responsible for some fatal envenomation of humans in South America inducing hemostatic disturbances in patients upon skin contact with the caterpillars' spines. Currently, only two species have been reported to cause hemorrhagic syndromes in humans: Lonomia achelous and Lonomia obliqua. However, species identifications have remained largely unchallenged despite improved knowledge of venom diversity and growing evidence that the taxonomy used over past decades misrepresents and underestimates species diversity. Here, we revisit the taxonomic diversity and distribution of Lonomia species using the most extensive dataset assembled to date, combining DNA barcodes, morphological comparisons, and geographical information. Considering new evidence for seven undescribed species as well as three newly proposed nomenclatural changes, our integrative approach leads to the recognition of 60 species, of which seven are known or strongly suspected to cause severe envenomation in humans. From a newly compiled synthesis of epidemiological data, we also examine the consequences of our results for understanding Lonomia envenomation risks and call for further investigations of other species' venom activities. This is required and necessary to improve alertness in areas at risk, and to define adequate treatment strategies for envenomed patients, including performing species identification and assessing the efficacy of anti-Lonomia serums against a broader diversity of species.

Acute kidney injury caused by venomous animals: inflammatory mechanisms

Either bites or stings of venomous animals comprise relevant public health problems in tropical countries. Acute kidney injury (AKI) induced by animal toxins is related to worse prognostic and outcomes. Being one the most important pathways to induce AKI following envenoming due to animal toxins, inflammation is an essential biological response that eliminates pathogenic bacteria and repairs tissue after injury. However, direct nephrotoxicity (i.e. apoptotic and necrotic mechanisms of toxins), pigmenturia (i.e. rhabdomyolysis and hemolysis), anaphylactic reactions, and coagulopathies could contribute to the renal injury. All these mechanisms are closely integrated, but inflammation is a distinct process. Hence, it is important to improve our understanding on inflammation mechanisms of these syndromes to provide a promising outlook to reduce morbidity and mortality. This literature review highlights the main scientific evidence of acute kidney injury induced by bites or stings from venomous animals and their inflammatory mechanisms. It included observational, cross-sectional, case-control and cohort human studies available up to December 2019. Descriptors were used according to Medical Subject Headings (MeSH), namely: “Acute kidney injury” or “Venom” and “Inflammation” on Medline/Pubmed and Google Scholar; “Kidney disease” or “Acute kidney injury” on Lilacs and SciELO. The present review evidenced that, among the described forms of renal inflammation, it can occur either directly or indirectly on renal cells by means of intravascular, systemic and endothelial hemolysis, activation of inflammatory pathway, as well as direct action of venom cytotoxic components on kidney structures.

The Latoia consocia Caterpillar Induces Pain by Targeting Nociceptive Ion Channel TRPV1

Accidental contact with caterpillar bristles causes local symptoms such as severe pain, intense heat, edema, erythema, and pruritus. However, there is little functional evidence to indicate a potential mechanism. In this study, we analyzed the biological characteristics of the crude venom from the larval stage of Latoia consocia living in South-West China. Intraplantar injection of the venom into the hind paws of mice induced severe acute pain behaviors in wild type (WT) mice; the responses were much reduced in TRPV1-deficit (TRPV1 KO) mice. The TRPV1-specific inhibitor, capsazepine, significantly attenuated the pain behaviors. Furthermore, the crude venom evoked strong calcium signals in the dorsal root ganglion (DRG) neurons of WT mice but not those of TRPV1 KO mice. Among the pain-related ion channels we tested, the crude venom only activated the TRPV1 channel. To better understand the venom components, we analyzed the transcriptome of the L. consocia sebaceous gland region. Our study suggests that TRPV1 serves as a primary nociceptor in caterpillar-induced pain and forms the foundation for elucidating the pain-producing mechanism.

Lonomia obliqua bristle extract modulates Rac1 activation, membrane dynamics and cell adhesion properties

Lonomia obliqua is a caterpillar of potential therapeutic interest whose venom is able to induce severe blood leakage and modulate leukocyte migration. Since both phenotypes are associated with changes in cytoskeleton dynamics and cell adhesion properties, the aim of this study was to analyze the effects of Lonomia obliqua bristle extract (LOBE) in cell adhesion and migration signaling. Proteomic analysis revealed that epithelial cells (CHO-K1) exposed to LOBE (30 μg/mL, 30 min) exhibited changes in levels of actin regulatory proteins, including RhoGTPases. These changes correlated with an increase in the activity of the RhoGTPase family member Rac as measured by Förster resonance energy transfer (FRET). When plated in migration promoting conditions, CHO-K1 cells exposed to LOBE (10 μg/mL) showed an increase in membrane ruffling after short (30 min) period of incubation that was accompanied by changes in the distribution of the adhesion markers paxillin, vinculin and an increase of focal adhesion kinase autophosphorylation levels (Y397), suggesting changes in cell-extracellular matrix (ECM) adhesion properties and signaling. These data suggest that LOBE possesses bioactive molecules that are capable to modulated cell migration signaling, cytoskeletal dynamics and cell-ECM properties of several cell types.

Venomous caterpillars: From inoculation apparatus to venom composition and envenomation

Envenomation by the larval or pupal stages of moths occurs when the victim presses their hairs. They penetrate the subcutaneous tissue, releasing toxins such as proteolytic enzymes, histamine and other pro-inflammatory substances. Cutaneous reactions, including severe pain, oedema and erythema are frequent local manifestations of caterpillar envenomation, but, in some cases, the reactions can evolve into vesicles, bullae, erosions, petechiae, superficial skin necrosis and ulcerations. Alternatively, some individual can develop allergic reactions, renal failure, osteochondritis, deformity and immobilization of the affected joints and intracerebral bleeding. Caterpillars produce venom to protect themselves from predators; contact with humans is accidental and deserves close attention. Their venoms have not been well studied, except for toxins from some few species. The present review brings together data on venomous caterpillars of moths, primarily addressing the available literature on diversity among the different families that cause accident in humans, the structures used in their defense, venom composition and clinical aspects of the envenomations. Understanding the molecular mechanisms of action of caterpillars' toxins may lead to the development of more adequate treatments.

Effectiveness of Lonomia antivenom in recovery from the coagulopathy induced by Lonomia orientoandensis and Lonomia casanarensis caterpillars in rats

In South America, accidental contact with Lepidoptera larvae can produce a diversity of reactions that vary from dermatological problems to severe hemorrhagic syndromes, such as those caused by contact with caterpillars of the genus Lonomia (Saturniidae). Lonomia venom can alter the hemostatic system and lead to renal failure, internal and brain bleeding, and in severe cases, death. The only specific treatment available for these envenomations is the Lonomia Antivenom (LAV) produced by the Butantan Institute, in Brazil, using an extract of Lonomia obliqua scoli as the antigen. LAV has been used to treat exposure to other Lonomia species across South America. However, no experimental studies have been performed to test the efficacy of LAV in neutralizing the venom of species other than L. obliqua found in Southern Brazil. In this study, we tested the effectiveness of LAV in reversing the hemostatic disturbances induced by injecting Lonomia casanarensis (Lca) and Lonomia orientoandensis (Lor) scolus extracts into rats and compared the effects to the case of L. obliqua (Lob) scolus extract-induced envenomation. Lca and Lor caterpillars were collected in Colombia, and some of them were reared to adults for identification. The Minimum Defibrinating Doses (MDD) of Lca and Lor were estimated. Rats were injected (i.d.) with a dose of 3 MDD per rat of each scolus extract and treated (i.v.) with 1.5 mL of LAV or 1.5 mL of saline. Twenty-four hours after the treatment, the fibrinogen levels and platelet counts had recovered to the hemostatic levels in the groups treated with LAV. The groups treated with the saline solution had fibrinogen levels and platelet counts at non-hemostatic levels. Thromboelastometric analyses confirmed these results. In conclusion, the results showed that LAV is effective at neutralizing the envenomation induced by Lca and Lor spine extracts in rats and restoring hemostasis.

Pro-inflammatory response and hemostatic disorder induced by venom of the coral snake Micrurus tener tener IN C57BL/6 mice

Micrurus venoms are known to induce mainly neurotoxicity in victims. However, other manifestations, including hemorrhage, edema, myotoxicity, complement activation, and hemostatic activity have been reported. In order to develop a more complete pharmacological profile of these venoms, inflammatory responses and hemostasis were evaluated in C57BL/6 mice treated with a sub-lethal dose of M. t. tener (Mtt) venom (8 μg/mouse), inoculated intraperitoneally. The venom induced moderate bleeding into the abdominal cavity and lungs, as well as infiltration of leukocytes into the liver. After 30 min, the release of pro-inflammatory mediators (TNF-α, IL-6, and NO) were observed, being most evident at 4 h. There was a decrease in hemoglobin and hematocrit levels at 72 h, a prolongation in coagulation times (PT and aPTT), a decrease in the fibrinogen concentration and an increase in fibrinolytic activity. In this animal model, it was proposed that Mtt venom induces inflammation with the release of mediators such as TNF-α, in response to the toxins. These mediators may activate hemostatic mechanisms, producing systemic fibrinolysis and hemorrhage. These findings suggest alternative treatments in Micrurus envenomations in which neurotoxic manifestations do not predominate.

Lonomia caterpillar envenoming in French Guiana reversed by the Brazilian antivenom: A successful case of international cooperation for a rare but deadly tropical hazard

In the American continent, larval forms (caterpillars) of the Lonomia genus can cause systemic reactions in human beings. In this Paper, we report the third case of Lonomia envenoming recorded in French Guiana in 25 years, and the first in which specific antivenom was administered. Severe symptoms of the envenoming were observed in our patient including pain; coagulopathy and systemic hemorrhage. They are caused by skin contact with caterpillars. Recovery, however, was quite satisfactory thanks to the international cooperation of the health authorities in both France and Brazil.

Acute kidney injury due to tropical infectious diseases and animal venoms: a tale of 2 continents

South and Southeast Asia and Latin American together comprise 46 countries and are home to approximately 40% of the world population. The sociopolitical and economic heterogeneity, tropical climate, and malady transitions characteristic of the region strongly influence disease behavior and health care delivery. Acute kidney injury epidemiology mirrors these inequalities. In addition to hospital-acquired acute kidney injury in tertiary care centers, these countries face a large preventable burden of community-acquired acute kidney injury secondary to tropical infectious diseases or animal venoms, affecting previously healthy young individuals. This article reviews the epidemiology, clinical picture, prevention, risk factors, and pathophysiology of acute kidney injury associated with tropical diseases (malaria, dengue, leptospirosis, scrub typhus, and yellow fever) and animal venom (snakes, bees, caterpillars, spiders, and scorpions) in tropical regions of Asia and Latin America, and discusses the potential future challenges due to emerging issues.

Systemic toxic effects induced by the aqueous extract of the fire coral Millepora complanata and partial purification of thermostable neurotoxins with lethal effects in mice

Millepora complanata is a cnidarian widely distributed in the coral reefs of the Mexican Caribbean. This species is popularly known as "fire coral", since contact with it causes severe pain, skin eruptions and blisters. Intravenous administration of of M. complanata aqueous extract induces violent convulsions and death in mice within 1 min (LD50=4.62µgprotein/g of body weight). Doses less than the LD50 produced histopathological damage in kidneys and lungs. Such histopathological damage was completely eliminated after incubation of the extract in heat denaturing conditions. Unexpectedly, the denatured extract conserved its lethal effect. These findings demonstrated that the extract contained hemolytic and phospholipase activities that might be responsible for the histopathological damage, and additionally it contained other unidentified thermostable toxins with lethal effects in mice. Chromatographic analysis of the extract led to the isolation of a 61 kDa vasoconstrictor protein. Furthermore, several non-peptidic vasoconstrictor fractions were separated. Particularly interesting was the fraction MC1-IIA obtained as a result of three-step chromatography processes (ion exchange, gel filtration and reverse phase). Like the original crude extract, this fraction induced vasoconstriction and delayed hemolysis and lethal effects in mice. A subsequent chromatographic analysis of MC1-IIA showed that this fraction contained at least four non-peptidic compounds. MS and NMR spectroscopic data analyses indicated that these metabolites were poly-oxygenated alkylbenzenes. The present study constitutes the first report of the presence of non-peptidic lethal toxins in an organism of the class Hydrozoa, and evidences the great structural diversity of the toxins produced by the Millepora species.

Acute Lonomia obliqua caterpillar envenomation-induced physiopathological alterations in rats: evidence of new toxic venom activities and the efficacy of serum therapy to counteract systemic tissue damage

The clinical manifestations of Lonomia obliqua caterpillar envenomation are systemic hemorrhage and acute kidney injury. In an effort to better understand the physiopathological mechanisms of envenomation, a rat model was established to study systemic tissue damage during L. obliqua envenomation. An array of acute venom effects was characterized, including biochemical, hematological, histopathological, myotoxic and genotoxic alterations. Rapid increases in serum alanine and aspartate transaminases, γ-glutamyl transferase, lactate dehydrogenase, hemoglobin, bilirubin, creatinine, urea and uric acid were observed, indicating that intravascular hemolysis and liver and kidney damage had occurred. Treatment with a specific antivenom (antilonomic serum) for up to 2 h post-venom injection neutralized the biochemical alterations. However, treatment after 6 h post-venom injection failed to normalize all biochemical parameters, despite its efficacy in reversing coagulation dysfunction. The hematological findings were consistent with hemolytic anemia and neutrophilic leukocytosis. The histopathological alterations were mainly related to hemorrhage and inflammation in the subcutaneous tissue, lung, heart and kidneys. Signs of congestion and hemosiderosis were evident in the spleen, and hemoglobin and/or myoglobin casts were also detected in the renal tubules. Increased levels of creatine kinase and creatine kinase-MB were correlated with the myocardial necrosis observed in vivo and confirmed the myotoxicity detected in vitro in isolated extensor digitorum longus muscles. Significant DNA damage was observed in the kidneys, heart, lung, liver and lymphocytes. The majority of the DNA lesions in the kidney were due to oxidative damage. The results presented here will aid in understanding the pathology underlying Lonomia's envenomation.

A pro-inflammatory profile of endothelial cell in Lonomia obliqua envenomation

Lonomia obliqua envenomation is characterized by intense local inflammatory reaction, which, dependent on the severity of the case, is followed by severe clinical manifestations related to hemorrhagic disorders that can lead to fatal outcome. These effects were imputed to several toxins present in L. obliqua venom, which are responsible for procoagulant, anticoagulant as well as antithrombotic activities, being also able to interfere with vascular cells functions. In this work, the intravital microscopy analysis show that after administration of low doses of L. obliqua venom (1-3 μg/ml) on hamster cheek pouch, there was no alterations neither on arterioles or venules caliber nor in the vascular permeability up to 30 min. However, after 10 min in contact with venom occurred a clear activation in the vascular bed, characterized by an increase in leukocyte rolling and adhesion on endothelium of hamster cheek pouch venules. A confocal analysis of vascular beds, confirmed these results showing an increase in endothelial E-selectin and VCAM-1 expression. The effects of L. obliqua venom on human endothelial cell (EC) in vitro were also investigated. The treatment of EC with venom (1-3 μg/ml) did not affect cell viability. However, at concentrations as low as 3 μg/ml of L. obliqua venom modifies actin cytoskeleton dynamics, and increases focal adhesion contacts, inducing stress fiber formation, focal adhesion kinase (FAK) phosphorylation and its subsequent association to actin. These effects are followed by the activation of NF-κB pathway, a critical signaling in several events associated to vascular inflammation. Accordingly, L. obliqua venom leads to a significant increase in COX-2, NOS-2, HO-1, MMP-2 and MMP-9 expression. Taken together the data show that, even at low concentrations, L. obliqua venom can activate endothelial cells, which assume a pro-inflammatory profile, contributing for local effects and probably also for systemic disturbances due to its ability to modulate the properties of the vascular system.

A mouse model to study the alterations in haemostatic and inflammatory parameters induced by Lonomia achelous caterpillar haemolymph

A mouse model was established to reproduce the haemorrhagic syndrome which occurs in humans after accidental contact with the hairs of the caterpillar Lonomia achelous (LA) and measures the haemostatic and inflammatory alterations that occur as a result of this contact. Mice were injected intradermally with different doses (0.4, 0.8 and 1.6 mg/animal) of L. achelous haemolymph (LAH). Haematological (haemoglobin, haematocrit, platelet count, differential leukocyte count), haemostatic (fibrinogen, plasminogen, factor XIII [FXIII], fibrinolytic activity) and inflammatory parameters (tumour necrosis factor alpha [TNF-α], nitric oxide [NO]) were measured at different times up to 48 h. C57BL/6 mice responded to LAH injection, in terms of these parameters, in a manner similar to that seen in humans, whereas the BALB/c mice were unresponsive. In C57BL/6 mice injected with LAH, time course measurements showed: a) a reduction in the haemoglobin, haematocrit, fibrinogen, FXIII and plasminogen levels, b) no effect on the platelet count and c) immediate leukocytosis and an increase in the fibrinolytic activity in plasma. An inflammatory response (TNF-α) was observed within 1 h post-injection, followed by a more persistent increase in serum NO. These findings suggest that C57BL/6 mice represent a useful model of the haemorrhagic syndrome observed in humans who have suffered contact with the caterpillar, permitting a deeper understanding of the role of the inflammatory response in the haematological and haemostatic manifestations of this syndrome.

The effects of Lonomin V, a toxin from the caterpillar (Lonomia achelous), on hemostasis parameters as measured by platelet function

Platelets play a central role in hemostasis during vascular injury. Patients affected with the hemorrhagic syndrome caused by contact with Lonomia achelous caterpillars (Lac) Lepidoptera distributed in various South American countries, show digestive, pulmonary and intraperitoneal bleeding in combination with hematomas and echymosis. In the present study, we have evaluated the effects of Lonomin V (serine protease isolated from Lac hemolymph) on some functional properties of platelets, evaluating its importance in primary hemostasis. Platelet adhesion to fibrinogen was reduced by 19, 20, 36, and 37% after pre-treated with 0.2, 2, 20 and 40 nM of Lonomin V, respectively. Pre-incubation of the platelets with 408 nM of Lonomin V, for 4 min at 37 °C, resulted in complete inhibition of the collagen-induced platelet aggregation, in contrast to 56% inhibition of the ADP - induced platelet aggregation. Lonomin V also inhibited anti-α(IIb)β(3) integrin binding to platelets by 56, 57, 52 and 54% at concentrations of 0.2, 2, 20 and 40 nM respectively. Additionally, Lonomin V inhibited anti-P-selectin binding to platelets by 28, 37, 33 and 33% at the same concentrations. The platelets tested with Lonomin V did not modify their viability. In summary, Lonomin V inhibited platelet aggregation, probably caused by the degradation of collagen. The anti-platelet activity of Lonomin V has been shown to be unique and a potentially useful tool for investigating cell-matrix and cell-cell interactions and for the development of antithrombotic agents in terms of their anti-adhesive activities.

Biochemistry of the envenomation response-A generator theme for interdisciplinary integration

The understanding of complex physiological processes requires information from many different areas of knowledge. To meet this interdisciplinary scenario, the ability of integrating and articulating information is demanded. The difficulty of such approach arises because, more often than not, information is fragmented through under graduation education in Health Sciences. Shifting from a fragmentary and deep view of many topics to joining them horizontally in a global view is not a trivial task for teachers to implement. To attain that objective we proposed a course herein described-Biochemistry of the envenomation response-aimed at integrating previous contents of Health Sciences courses, following international recommendations of interdisciplinary model. The contents were organized by modules with increasing topic complexity. The full understanding of the envenoming pathophysiology of each module would be attained by the integration of knowledge from different disciplines. Active-learning strategy was employed focusing concept map drawing. Evaluation was obtained by a 30-item Likert-type survey answered by ninety students; 84% of the students considered that the number of relations that they were able to establish as seen by concept maps increased throughout the course. Similarly, 98% considered that both the theme and the strategy adopted in the course contributed to develop an interdisciplinary view.

Lonomia obliqua venom: In vivo effects and molecular aspects associated with the hemorrhagic syndrome

Caterpillar envenomation has been an emergent health issue. Lonomia obliqua is a medically important animal that causes a hemorrhagic syndrome that can progress to acute renal failure, intracranial hemorrhage and death. In the past few years the molecular characterization of L. obliqua venom in addition to experimental models has provided fundamental information to the understanding of the envenomation syndrome. Herein studies from several authors which characterized the complex toxic-pharmacological actions of whole venom are reviewed.

Antilonomic Effects of Brazilian Brown Seaweed Extracts

The aim of this work was to investigate the hemolysis and blood clotting activity of Lomonia obliqua venom and the ability of some Brazilian marine algal extracts ( Canistrocarpus cervicornis, Stypopodium zonale and Dictyota pfaffi) to antagonize such biological activities. L. obliqua caterpillars are dangerous to human beings and envenomation symptoms are characterized by hemorrhagic, hemolytic and blood clotting disorders, and acute renal failure, which sometimes lead to the death of the victims. Through in vitro experiments we have shown that L. obliqua venom is able to clot human plasma and hemolize human erythrocytes and that the coagulation activity of the venom is inhibited by the extracts of C. cervicornis, S. zonale and D. pfaffi. In contrast, C. cervicornis and S. zonale extracts did not inhibit the hemolytic activity of L. oblqua, as did the extract of D. pfaffi. These finding indicate that marine algae may be used as antivenoms or may contribute to the development of compounds with antilonomic effects.

Lonomia obliqua caterpillar envenomation causes platelet hypoaggregation and blood incoagulability in rats

Envenomation caused by Lonomia obliqua is a public health hazard in Southern Brazil. Envenomed victims present severe hemorrhagic syndrome that can progress to intracranial hemorrhage and death. To understand the mechanisms that lead to hemorrhage, we investigated the platelet dysfunction and blood coagulation disturbances following experimental envenomation in rats. L. obliqua bristle extract was injected (s.c.) and blood collected at different times post-venom administration for determination of platelet response and analysis of blood coagulation. Rats presented hypofibrinogenemia and platelet hypoaggregation in platelet rich plasma (PRP). After addition of exogenous fibrinogen to PRP, platelet hypoaggregation was not corrected. Interestingly, normoaggregation was observed when platelets were separated from plasma. In addition, incubation of plasma from envenomed rats inhibits aggregation response of normal washed platelets. These results indicate that an aggregation inhibitor is generated in plasma during envenomation. Moreover, rats presented an increase in nitric oxide plasmatic levels which coincided with maximum inhibition in platelet aggregation. Animals also showed blood incoagulability and a significant increase in thrombin, plasmin and urokinase plasmatic activities. Despite this intravascular thrombin generation, only a slight decrease in platelet numbers was detected. Certainly, the platelet hypoaggregation and blood incoagulability described herein contribute to systemic bleeding observed in patients.

Novel perspectives on the pathogenesis of Lonomia obliqua caterpillar envenomation based on assessment of host response by gene expression analysis

Animal venomous secretions have been explored as source of active substances affecting mammal hemostasis. These active principles impinge on key elements of almost all physiologic pathways and have an enormous potential in the development of new therapeutic drugs. The envenomation caused by the caterpillar Lonomia obliqua (lonomism) is characterized by a hemorrhagic clinical profile. Investigations of caterpillar venom have, in general, involved the isolation and biochemical characterization of active principles related to the pathophysiology of envenomation. In the last few years, these studies focused on the caterpillar's secretions pro-coagulant, fibrin(ogen)olytic, hemolytic, edematogenic and nociceptive activities. Recently, a significant advance was achieved as a result of a transcriptome study, which generated a catalog of putative toxic proteins in the caterpillar venom, giving rise to hypotheses on the molecular basis of pathogenesis which could be experimentally explored. In this investigation, using a microarray methodology, we analyzed the effects of the caterpillar venom on the gene expression profile of cultured human fibroblasts with the aim of gaining insight into genes possibly associated with the clinical manifestations of lonomism. Our hypothesis was that both the direct action L. obliqua venomous proteins on the host as well as an indirect effect caused by alteration in the gene expression pattern in host tissues could function in concert and perhaps synergistically to give rise to the profound symptoms observed during lonomism. Interesting changes in the expression pattern of some genes, such as IL-8, prostaglandin-endoperoxide synthase 2, urokinase-type plasminogen activator receptor and tissue factor, were observed in treated fibroblasts, which could contribute to some of the observed pathological sequela in lonomism. Thus, lonomism appears to be a result of both the previously described direct effects of the venom as well as indirect effects caused by changes in host gene expression profiles. These studies have enhanced our understanding of lonomism and may contribute to insights into more effective treatments.

Immunochemical and proteomic technologies as tools for unravelling toxins involved in envenoming by accidental contact with Lonomia obliqua caterpillars

The accidental contact with Lonomia obliqua caterpillar causes local and systemic symptoms (such as fibrinogen depletion), leading, in some cases, to serious clinical complications (acute renal failure and intracranial haemorrhage). Fortunately, a successful therapeutical approach using anti-Lonomic serum, produced in horses against L. obliqua's bristle extract, has already been put in place. However, a global view of immunogenic toxins involved in the coagulation disorders could help to elucidate the envenoming process. In the present study, our aim was to identify bristle extract's immunogenic components, especially those related to the haemostasis, coupling proteomics and immunochemical approaches (bidimensional electrophoresis, mass spectrometry and immunoblotting). The bidimensional map of bristle extract showed a broad profile of 157 silver-stained spots, where at least 153 spots were immunochemically revealed. Twenty-four of these spots were submitted to sequencing by mass spectrometry and three different categories of proteins were identified: lipocalins, cuticle proteins and serpins. From these protein families, it was observed that the most abundant was the lipocalin family, specifically represented by different isoforms of Lopap (a prothrombin activator protein), reinforcing its relevance during envenoming. Peptide sequences of several other immunochemically revealed spots showed no correspondence to any known sequence and were classified as unknown proteins. These proteins could represent new immunogenic molecules and/or toxins. The sequences presented in this article can be used for oligonucleotide design aiming the amplification of cDNAs coding for new molecules using L. obliqua bristles' cDNA libraries or isolated RNAs as template.

The action of Lonomin V (Lonomia achelous) on fibronectin functional properties

Lonomia achelous caterpillar, Lepidoptera distributed along some South American countries, induces a hemorrhagic syndrome in people who come into contact with its bristles. A clinical characteristic in these patients is that fresh healed wounds are re-opened and bleed. In order to explain this symptomatology, we evaluated the effect of Lonomin V (a protein isolated from L. achelous hemolymph), on some functional properties of fibronectin, which in turn plays an important role in the hemostasis. The effect of Lonomin V on fibronectin was studied by SDS-PAGE in reduced condition, binding to gelatin and heparin, crosslinking to fibrin and platelet adhesion. Formation of degradation products of 120, 66, 50, 40 and 29 kDa, some of which retain affinity to heparin and gelatin were observed; however, the fibronectin degradation fragments presented a significant decrease of crosslinking capacity to fibrin and platelet adhesion, suggesting that the proteolysis of fibronectin by Lonomin V induces changes in its crosslinking sites and on platelet receptors. These findings might partially explain the wound dehiscence observed in the patients. Due to its effect on adhesive proteins with concomitant impairment of some functional properties, Lonomin V might be useful for cellular adhesion studies involved in hemostasis such as platelet adhesion.

The venom of the Lonomia caterpillar: an overview

Contact with the Lonomia caterpillar causes numerous accidents, especially in Venezuela and the southern region of Brazil, where it is considered a public health problem. The Lonomia obliqua venom causes disseminated intravascular coagulation and a consumptive coagulopathy, which can lead to a hemorrhagic syndrome. The venom of Lonomia achelous also causes hemorrhage, but through increased fibrinolysis. In vivo and in vitro studies have shown that the venom of the Lonomia caterpillar contains several toxins with procoagulant, anticoagulant and antithrombotic activities. These toxins also affect the endothelium. The recent construction of cDNA libraries of the transcripts from L. obliqua bristles enables the use of biotechnological approaches to study the venom. This paper presents an overview of the biochemical and biological properties of Lonomia caterpillar venom, discussing aspects of human accidents, experimental envenomation, toxins and targets and future perspectives.

Kallikrein-kinin system activation by Lonomia obliqua caterpillar bristles: involvement in edema and hypotension responses to envenomation

Lonomia obliqua envenomation induces an intense burning sensation at the site of contact and severe hemorrhage followed by edema and hypotension, and after few days death can occur usually due to acute renal failure. In order to understand more about the envenomation syndrome, the present study investigates the role played by kallikrein-kinin system (KKS) in edematogenic and hypotensive responses to the envenomation by L. obliqua. The incubation of L. obliqua caterpillar bristles extract (LOCBE) with plasma results in kallikrein activation, measured by cromogenic assay using the kallikrein synthetic substrate S-2302 (H-D-Pro-Phe-Arg-pNA). It was also showed that LOCBE was able to release kinins from low-molecular weight kininogen (LMWK). Moreover, it was demonstrated that previous administration of a kallikrein inhibitor (aprotinin) or bradykinin B2 receptor antagonist (HOE-140) significantly reduces the edema and hypotension in response to LOCBE, using mouse paw edema bioassay and mean arterial blood pressure analysis, respectively. The results demonstrate a direct involvement of the KKS in the edema formation and in the fall of arterial pressure that occur in the L. obliqua envenomation syndrome.

Degradation of extracellular matrix proteins (fibronectin, vitronectin and laminin) by serine-proteinases isolated from Lonomia achelous caterpillar hemolymph

Lonomia achelous is a caterpillar distributed in southern Venezuela and in northern Brazil that causes an acute hemorrhagic syndrome in people who have contact with its bristles. The effect of the crude hemolymph and its chromatographic fractions (FDII, Lonomin V and Lonomin V-2) on extracellular matrix proteins was studied. The chromatographic fractions show activities similar to plasmin and urokinase. In sodium dodecyl sulfate-polyacrylamide gel electrophoresis, both lonomins appear as a protein band of 25 kDa under reduced conditions. By exclusion chromatography, the molecular weights of Lonomin V and Lonomin V-2 were 26.5 and 24.5 kDa, respectively. Fibronectin, laminin and vitronectin were degraded by all venom components. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, under reduced conditions, shows that lonomins degrade fibronectin in four main fragments of 116, 60, 50 and 30 kDa. Molecular exclusion chromatography in native conditions shows that the molecular masses of these fragments are > or = 300, 62 and 27 kDa. The proteolytic effect of lonomins was abolished by benzamidine/HCl, iodoacetic acid and aprotinin. The extracellular matrix protein degradation together with the fibrino(geno)lytic activity of hemolymph and its fractions could explain, in part, the hemorrhagic syndrome, and the wound dehiscence in persons who have had contact with the L. achelous caterpillar.

Acute renal failure provoked by toxin from caterpillars of the species Lonomia obliqua

Acute renal failure (ARF) is a complication of envenoming by contact with caterpillars of the species Lonomia obliqua. A cohort study was conducted to evaluate development of acute and chronic renal failure (CRF) in patients who been in contact with L. obliqua during the period from 1989 to 2003 in the State of Santa Catarina, southern Brazil. Patients were evaluated in two distinct groups: those prior to 1995, who did not receive specific treatment of any type, and those after this date who were treated with antilonomic serum (SALon). The presence of creatinine > or = 1.5 mg/dl in patients who had no history of previous renal illness was considered to be indicative of acute kidney failure. Of the 2067 patients evaluated, 39 (1.9%) developed ARF. Eleven (32%) of these patients were treated with dialysis and four (10.3%) developed CRF. The seven deaths (4%) occurred in the period before treatment with SALon. Blood coagulation measures (TC, TP, and TTPA), were significantly longer in the group with ARF. All patients with ARF and 67% of the control group presented hematuria. The majority of the patients recovered prior renal function, however, four (10.3%) needed chronic dialysis. Envenoming by L. obliqua can be considered an important risk factor for the development of potentially fatal ARF, as well as for developing CRF.

Immunochemical detection of Lonomia obliqua caterpillar venom in rats

Severe cases of human envenoming by caterpillars of the saturniid moth Lonomia obliqua in Brazil can result in renal damage, leading to renal failure, and intracerebral hemorrhaging. In this work, we used immunohistochemical staining with rabbit antiserum raised against L. obliqua venom to examine venom distribution in selected tissues of the brain (cerebellum and hippocampus), kidneys, and liver of male Wistar rats injected with a single dose of venom (200 microg/kg, i.v.) and sacrificed 6, 18, 24, and 72 hours later. The immunolabeling of GFAP was also examined to assess the venom effects on perivascular astrocytic end-feet in the microvasculature of the hippocampus and cerebellum. Venom was detected in the kidneys (6 and 18 hours) and in the liver (6 hours) but not in the brain at any of the time intervals examined. In contrast, immunolabeling for GFAP revealed astrogliosis in the cerebellum and enhanced expression of this protein in the glial processes of the cerebellum and hippocampus, with a maximum response from 24 hours onwards. The high immunoreactivity seen in the kidneys agreed with the renal damage and dysfunction reported for some patients. The lack of venom detection in the brain, despite the altered expression of GFAP in astrocytes, suggested either that the venom does not enter this organ or that its entrance is transient and fast. Alternatively, the circulating venom may induce the release of mediators that could serve as second messengers to provoke the late astrocytic reactivity and astrogliosis. It is possible that both of these mechanisms may contribute to the effects observed.

Lonofibrase, a novel alpha-fibrinogenase from Lonomia obliqua caterpillars

Envenomation caused by Lonomia obliqua caterpillars is an increasing problem in Southern Brazil. The clinical profile is characterized by a profound hemorrhagic disorder. In the present study, we describe the characterization of a fibrin(ogen)olytic factor (lonofibrase) isolated from a venomous secretion of the caterpillars. The crude extract showed a dose-dependent inhibitory effect in the rate of thrombin-induced fibrinogen clotting and produced fragmentation of fibrinogen. Isolation of the fibrin(ogen)olytic enzyme was achieved by combining ion exchange chromatography followed by gel filtration in a fast protein liquid chromatography (FPLC) system. A single 35-kDa band was identified and the isolated enzyme named lonofibrase. Lonofibrase rapidly degrades Aalpha and Bbeta chains of fibrinogen, also being able to cleave fibrin in a distinct way from that observed with plasmin. The presence of lonofibrase with both fibrinogenolytic and fibrinolytic activities in L. obliqua secretion is coherent with the severe hemorrhagic clinical profile resulting from envenomation caused by these insects.

Lonomia obliqua caterpillar venom increases permeability of the blood-brain barrier in rats

Human envenoming by caterpillars of the saturniid moth Lonomia obliqua in southern Brazil produces a mild local response (erythema, some edema, and pain) and systemic effects that include incoagulable blood, renal failure and in severe accidents intracerebral hemorrhage. In this work, we used light and electron microscopy to investigate the morphological alterations in the brain and blood-brain barrier of rats injected intravenously with venom from L. obliqua spicules (200 microg/kg). Five semi-purified fractions of venom (200 microg/kg each) were also assayed. Quantitative morphological and ultrastructural analyses were done 6, 18, 24 and 72 h after the i.v. injection of venom and its fractions. Light microscopy showed that 6h after envenoming there was cerebellar edema, which decreased by 72 h. Intracerebral hemorrhage occurred in only one rat 24h after the injection of venom. Blood-brain barrier (BBB) breakdown, assessed by transmission electron microscopy based on the passage of an extracellular tracer (lanthanum nitrate) between brain capillary endothelial cells, was observed in the cerebellum and hippocampus 18 h after venom injection. At this time, the cerebellum was more sensitive to the venom than the hippocampus, as shown by the greater number of leaky vessels. The number of capillaries showing breakdown was lower after 72 h than after 18 h. None of the semi-purified fractions significantly increased the number of leaky vessels. These results indicate that L. obliqua caterpillar venom has a deleterious action on the rat BBB. The lack of effect of the venom fractions when administered alone suggested that a synergistic action of venom components may be responsible for the damage seen in the central nervous system, but this was not confirmed when three combinations of the fractions were tested.

Nociceptive and edematogenic responses elicited by a crude bristle extract of Lonomia obliqua caterpillars

Lyophilized Lonomia obliqua crude bristle extract (LOCBE) diluted in physiological saline (15, 35 and 50 microg of protein/paw) was injected in the plantar surface of the hind paw of the rat, causing a nociceptive response which lasted from 30 to a maximum of 50 min, peaking in the first 5 min. The animals also presented hematuria and nasal bleeding. Nociception was inhibited by indomethacin pretreatment (2.5 mg/kg, i.p., 60 min before), but not by guanethidine (30 mg/kg/day, s.c., for 3 days) or loratadine (5 mg/kg, p.o., 60 min before). LOCBE injection also produced paw edema peaking 1 h after injection and lasting for 6 h. Loratadine pretreatment, but neither guanethidine nor indomethacin, reduced edema. After the period of overt nociception, a nociceptive aftersensation response could be evoked up to 6 h after by immersing the paw into cold water (15 degrees C) for 10 s. Capsaicin (1.6 microg), formalin (0.5%) or prostaglandin E(2) (500 ng) did not produce the same aftersensation phenomenon. These results suggest that LOCBE-induced nociception is largely facilitated by prostaglandin production, and edematogenic response seems to be facilitated by prostanoids and histamine. Finally, LOCBE induced a state of sensitization to cold, which seemed to be specific as it was not caused by other noxious chemicals.

In vitro hemolytic activity of Lonomia obliqua caterpillar bristle extract on human and Wistar rat erythrocytes

Human accidental envenomation caused by skin contact with the bristles of Lonomia obliqua caterpillar causes coagulation and fibrinolysis disorders. Alterations of hematologic parameters are observed only in severe cases of envenomation, but with no clinical evidence of intravascular hemolysis. However, since we have observed intravascular hemolysis in preliminary studies using Wistar rats as an experimental model for investigating L. obliqua envenomation, the objective of the present study was to investigate the in vitro hemolytic activity of the bristle extract of L. obliqua caterpillars on human and rat erythrocytes. Our results showed that the bristle extract has indirect and direct hemolytic activity on human and rat erythrocytes, although direct hemolytic activity was only observed at higher bristle extract concentrations. We also observed that the bristle extract has a proteolytic activity on band 3 of human and rat erythrocyte membranes. Thus, crude L. obliqua bristle extract was found to contain at least two components with hemolytic activity on erythrocytes, a phospholipase enzyme and another protein with a direct activity on the erythrocyte membrane.

Overview of tropical nephrology

Tropical nephrology covers renal diseases commonly seen in the tropics and elsewhere and specific tropical renal diseases seen mostly or only in the tropical area. Emphasis in this article is placed on the latter category, which includes renal involvement in tropical infectious diseases, natural toxin poisoning, and environmental renal problems. Pathologically, all renal structures can be affected. There is, therefore, a broad spectrum of pathologic changes, and clinical renal manifestations vary from mild urinary sediment changes to acute renal failure. Inflammatory processes plays an essential role in the pathogenesis of renal involvement in infection and toxin groups. Both models share the same inflammatory pathways through cytokines, chemokines, and mediators. Hemodynamic alterations, immune response, and direct nephrotoxicity are involved in the development of renal lesions.

Antithrombotic effect of Lonomia obliqua caterpillar bristle extract on experimental venous thrombosis

The venom of Lonomia obliqua caterpillar may induce a hemorrhagic syndrome in humans, and blood incoagulability by afibrinogenemia when intravenously injected in laboratory animals. The possible antithrombotic and thrombolytic activities of L. obliqua caterpillar bristle extract (LOCBE) were evaluated in this study. The minimal intravenous dose of the extract necessary to induce afibrinogenemia and anticoagulation was 3.0 and 10.0 microg protein/kg body weight for rabbits and rats, respectively. In rabbits, this dose induced total blood incoagulability for at least 10 h and did not reduce the weight of preformed venous thrombi, in contrast to streptokinase (30,000 IU/kg). In rats, pretreatment with 5.0 and 10.0 microg/kg LOCBE prevented the formation of thrombi induced by venous stasis or by injury to the venous endothelium. The dose of 5.0 microg/kg LOCBE did not modify blood coagulation assay parameters but increased bleeding time and decreased plasma factor XIII concentration. When the extract was administered to rats at the dose of 10.0 microg/kg, the blood was totally incoagulable for 6 h. These data show that LOCBE was effective in preventing experimental venous thrombosis in rats, justifying further studies using purified fractions of the extract to clarify the mechanisms of this effect.

Thrombolytic effect of lonomin V in a rabbit jugular vein thrombosis model

Thrombolytic efficacy of lonomin V (LV), a protein isolated from Lonomia achelous caterpillars haemolymph, administered either as a single intravenous bolus or as a continuous infusion, was evaluated in a rabbit jugular vein thrombosis model, and compared with those of single-chain tissue-type plasminogen activator (sct-PA) and two-chain urokinase-type plasminogen activator (tcu-PA). As a bolus LV, at doses of 100 000 IU/kg body weight (bw) produced an activator-induced thrombolysis (AIL) of 50.94% +/- 12.4 compared with 14.4% +/- 10.8 for tcu-PA at the same dose. As a continuous infusion at doses of 200 000 IU/kg bw LV produced an AIL of 45.8%, whereas sct-PA and tcu-PA produced an AIL of 69.9 and 33.7%, respectively. Fibrinogen, plasminogen and alpha-2-antiplasmin levels decreased significantly with the higher doses of LV, sct-PA, and tcu-PA. Factor XIII levels were significantly reduced in a dose-dependent manner only with LV. In conclusion, LV produces a dose-dependent thrombolysis in combination with a decrease in factor XIII activity.