Fibrinolysis produced by contact with a caterpillar

Effect of Lonomia obliqua Venom on Human Neutrophils

The significant incidence of deforestation in South America culminates in the contact of humans with typical forests species. Among these species, one may highlight Lonomia obliqua caterpillar, which, when touched by humans, can poison them through their bristles. Therefore, better acknowledging the mechanisms involved in envenomation caused by Lonomia obliqua caterpillar bristle extract (LOCBE) may contribute to further treatments. Recently, we demonstrated that LOCBE induces a pro-inflammatory profile in endothelial cells; thus, we decided to investigate the effects of LOCBE on human polymorphonuclear neutrophils (PMN), which are the first leukocytes that migrate to the inflammatory focus. Our results showed that treatment with LOCBE induced PMN chemotaxis together with alterations in actin cytoskeleton and focal adhesion kinase (FAK) activation, favoring migration. Concurrently, LOCBE induced PMN adhesion to matrix proteins, such as collagen IV, fibronectin, and fibrinogen. Moreover, we observed that LOCBE attenuated PMN apoptosis and increased reactive oxygen species (ROS) production together with nuclear factor kB (NF-κB) activation—a redox-sensitive transcription factor—as well as interleukin (IL)-1β and IL-8 release. We call attention to the ROS-dependent effect of LOCBE on increased cell migration once an antioxidant treatment reverted it. In summary, we report that LOCBE activates PMN, inducing pro-inflammatory responses modulated by ROS.

Lonomia obliqua Envenoming and Innovative Research

As a tribute to Butantan Institute in its 120th anniversary, this review describes some of the scientific research efforts carried out in the study of Lonomia envenoming in Brazil, a country where accidents with caterpillars reach over 42,000 individuals per year (especially in South and Southeast Brazil). Thus, the promising data regarding the studies with Lonomia’s toxins contributed to the creation of new research centers specialized in toxinology based at Butantan Institute, as well as to the production of the antilonomic serum (ALS), actions which are in line with the Butantan Institute mission “to research, develop, manufacture, and provide products and services for the health of the population”. In addition, the study of the components of the Lonomia obliqua bristle extract led to the discovery of new molecules with peculiar properties, opening a field of knowledge that could lead to the development and innovation of new drugs aimed at cell regeneration and inflammatory diseases.

A hidden deadly venomous insect: First eco-epidemiological assessment and risk mapping of lonomism in Argentina

BACKGROUND

Envenomation by the South American Lonomia saturniid caterpillars, named lonomism, constitutes an emerging and somewhat neglected public health issue in Argentina and neighboring countries. Considering that there is an intricate relationship between environment and human health in such cases, this study aimed to analyze the eco-epidemiological profile of 40 accidents and 33 occurrences of Lonomia spp. in Misiones (Argentina) between January 2014 and May 2020.

METHODOLOGY/PRINCIPAL FINDINGS

We described the eco-epidemiological variables and characterized the abiotic scenario of such cases. Additionally, we obtained a density map that shows the punctual intensity of Lonomia records throughout Misiones. Most of the accidents occurred in the Department of Guaraní and involved male victims younger than 20 years old. The accidental/occasional occurrence of Lonomia spp. (considering both adult and caterpillar stages together) was significantly higher in the rural area, whereas only adult specimens were found in urban areas. We determined that the presence of this insect in Misiones is positively related to higher temperatures and solar radiation, and larger precipitation and evapotranspiration throughout the year.

CONCLUSION/SIGNIFICANCE

This study represents an initial step towards the global understanding of lonomism as a public health problem in Argentina. It provides a map of the risk level for this envenomation in Misiones, which could help authorities address public health policy efforts to implement sustainable strategies for prevention and response to this threat in Northeastern Argentina and neighboring regions.

Arthropod venoms: Biochemistry, ecology and evolution

Comprising of over a million described species of highly diverse invertebrates, Arthropoda is amongst the most successful animal lineages to have colonized aerial, terrestrial, and aquatic domains. Venom, one of the many fascinating traits to have evolved in various members of this phylum, has underpinned their adaptation to diverse habitats. Over millions of years of evolution, arthropods have evolved ingenious ways of delivering venom in their targets for self-defence and predation. The morphological diversity of venom delivery apparatus in arthropods is astounding, and includes extensively modified pedipalps, tail (telson), mouth parts (hypostome), fangs, appendages (maxillulae), proboscis, ovipositor (stinger), and hair (urticating bristles). Recent investigations have also unravelled an astonishing venom biocomplexity with molecular scaffolds being recruited from a multitude of protein families. Venoms are a remarkable bioresource for discovering lead compounds in targeted therapeutics. Several components with prospective applications in the development of advanced lifesaving drugs and environment friendly bio-insecticides have been discovered from arthropod venoms. Despite these fascinating features, the composition, bioactivity, and molecular evolution of venom in several arthropod lineages remains largely understudied. This review highlights the prevalence of venom, its mode of toxic action, and the evolutionary dynamics of venom in Arthropoda, the most speciose phylum in the animal kingdom.

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.

Effects of Lonomia obliqua Venom on Vascular Smooth Muscle Cells: Contribution of NADPH Oxidase-Derived Reactive Oxygen Species

Envenomation caused by human contact with the caterpillar Lonomia is characterized by deleterious effects on coagulation and patency of blood vessels. The cellular effects induced by Lonomia obliqua venom highlights its capacity to activate endothelial cells, leading to a proinflammatory phenotype. Having more knowledge about the mechanisms involved in envenomation may contribute to better treatment. We aimed to evaluate the effects of Lonomia obliqua caterpillar bristle extract (LOCBE) on vascular smooth muscle cells (VSMC). We observed that LOCBE induced VSMC migration, which was preceded by alterations in actin cytoskeleton dynamics and Focal Adhesion Kinase activation. LOCBE also induced Extracellular Signal-Regulated Kinase (ERK) phosphorylation in VSMC, and the inhibition of this pathway impaired cell proliferation. Stimulation of VSMC with LOCBE triggered reactive oxygen species (ROS) production through the activation of NADPH oxidase. The rapid increase in these ROS further induced mitochondrial ROS production, however only NADPH oxidase-derived ROS were involved in ERK activation in VSMC. We that demonstrated the chemotactic and proliferative effects of LOCBE on VSMC were dependent on ROS production, mainly through NADPH oxidase. Together, the data show that Lonomia obliqua venom can interact with and activate VSMC. These effects rely on ROS production, suggesting new potential targets for treatment against vascular damage during envenomation.

Hemostatic disorders induced by skin contact with Lonomia obliqua (Lepidoptera, Saturniidae) caterpillars

Patients envenomed by Lonomia sp caterpillars initially experience a mild burning pain, headache, nausea, vomiting, and skin and mucosal hemorrhages. Some patients can rapidly progress to a severe coagulopathy that presents as visceral or intracerebral hemorrhaging. We studied the hemostatic alterations that occurred in 14 patients who were envenomed by Lonomia obliqua in Southern Brazil and presented at the Hospital São Vicente de Paulo (Passo Fundo, RS), Brazil during the summers of 1993 and 1994 when Lonomia antivenom was not yet available for treatment. The patients were classified into to 4 clinical groups: 0 (two patients), I (eight patients), II (two patients), and III (two patients). The patients were admitted to the hospital between 4 hours and five days after contact with the caterpillars. In this study, the coagulation parameters of the patients were followed up for up to 172 hours after the accidents. The patients received no treatment with the exceptions of two patients who received blood transfusions and antifibrinolytic treatment. The observed abnormalities related to blood coagulation and fibrinolytic factors were similar regardless of the severity of the bleeding symptoms. These findings suggest that alterations in hemostatic parameters without thrombocytopenia are not predictors of the seriousness of such accidents. Thus, consumptive disorder and reactive fibrinolysis are not proportional to mild coagulopathy. Furthermore, these patients recovered. The hemostatic parameters of most of the patients normalized between 96 and 120 h after the accident.

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.

Lonomia obliqua Walker (Lepidoptera: Saturniidae): hemostasis implications

Summary In southern Brazil, since 1989, several cases of accidents produced by unwilling contact with the body of poisonous caterpillars of the moth species Lonomia obliqua Walker, 1855 (Lepidoptera: Saturniidae), were described. L. obliqua caterpillars have gregarious behavior and feed on leaves of host trees during the night, staying grouped in the trunk during the day, which favors the occurrence of accidents with the species. This caterpillar has the body covered with bristles that on contact with the skin of individuals, breaks and release their contents, inoculating the venom into the victim. The basic constitution of the venom is protein and its components produce physiological changes in the victim, which include disturbances in hemostasis. Hemorrhagic syndrome associated with consumption coagulopathy, intravascular hemolysis and acute renal failure are some of the possible clinical manifestations related to poisoning by L. obliqua. Specific laboratory tests for diagnosis of poisoning have not been described previously. The diagnosis of poisoning is made based on the patient's medical history, clinical manifestations, erythrocyte levels, and, primarily, parameters that evaluate blood coagulation. Treatment is performed with the use of supportive care and the administration of specific hyperimmune antivenom. Poisoning can be serious and even fatal.

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.

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.

Fatal intracerebral hemorrhage secondary to Lonomia obliqua caterpillar envenoming: case report

The case of a 70 year-old, previously healthy woman who developed a severe bleeding diathesis shortly after touching a Lonomia obliqua caterpillar and finally died from multiple intracerebral hemorrhages is described. Brain hemorrhages are the leading cause of death in patients envenomed by the Lonomia species. The pertinent literature is reviewed and the most relevant clinical features highlighted, with emphasis on diagnosis. The use of new therapeutic options such as anti-Lonomia serum is discussed.

Efficacy of serum therapy on the treatment of rats experimentally envenomed by bristle extract of the caterpillar Lonomia obliqua: Comparison with epsilon-aminocaproic acid therapy

Large number of accidents caused by contact with Lonomia obliqua caterpillars, with hemorrhagic complications, have occurred in southern Brazil. Based on Venezuelan expertise to treat Lonomia achelous envenomation, the use of the antifibrinolytic drug epsilon-aminocaproic acid (EACA) has been indicated to treat L. obliqua envenomation, although no evidence has been presented to justify its use. Specific antivenom (antilonomic serum (ALS)) that neutralizes toxins that cause envenomation was developed. To compare the effectiveness of such treatments, rats were injected i.d. with the bristle extract of L. obliqua caterpillars and treated 15 min, 1 and 6 h after with saline, ALS, EACA, or with both ALS and EACA. ALS elicited fibrinogen recovery and normalization of thrombin time (TT), prothrombin time (PT) and activated partial thromboplastin time (APTT), independent of when it was administered; however, hematocrit was decreased in the group treated later. Saline or EACA-treated groups presented neither fibrinogen recovery nor normalization of hemostatic parameters. A high death rate was observed in the group treated with EACA 15 min after the envenomation. Prolongation of TT and APTT observed in the group treated with EACA and ALS indicated that this association gave no benefit in relation to the group treated solely with ALS. The results presented herein suggest that ALS is the only effective treatment for envenomation caused by contact with Lonomia obliqua caterpillars and indicate that EACA should not be administered in the initial phase of envenomation.

Proteases from Lonomia obliqua venomous secretions: comparison of procoagulant, fibrin(ogen)olytic and amidolytic activities

The hemorrhagic syndrome caused by Lonomia obliqua caterpillars is an increasing problem in Southern Brazil. The clinical profile is characterized by both hemorrhagic and pro-coagulant symptoms, constituting a paradoxical action of the venom. The effects upon blood coagulation and fibrin(ogen)olysis have been shown to result from the combined action of several active principles found mostly in the bristle extract. The present study reports quali-quantitative differences among L. obliqua secretions: Cryosecretion, hemolymph, bristle extract and tegument extract. Cryosecretion and hemolymph displayed strong amidolytic activity upon several substrates, presented moderated procoagulant activity and high fibrinogen degrading ability. Bristle and tegument extracts presented low amidolytic activity, but bristle extract showed the most potent procoagulant activity and both extracts presented low fibrinogen degrading ability. The differential involvement of these secretions during the accidents with L. obliqua can elucidate the different symptoms presented after envenomation.

Acidentes por lepidópteros (larvas e adultos de mariposas): estudo dos aspectos epidemiológicos, clínicos e terapêuticos

Os autores apresentam e discutem aspectos dos acidentes causados por larvas de lepidópteros (mariposas), enfatizando as manifestações dermatológicas e a dor intensa que caracterizam estes agravos. Além disso, são apresentadas larvas de mariposas que causam manifestações extracutâneas, tais como severos distúrbios de coagulação e artropatias anquilosantes, e ainda dermatites provocadas por insetos adultos. Os principais grupos de lepidópteros causadores de acidentes em humanos são demonstrados, e as medidas terapêuticas atualizadas são discutidas. O lepidopterismo e o erucismo são acidentes comuns, e é importante que o dermatologista saiba reconhecer e tratar esse tipo de envenenamento.

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.

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.

Efficacy of two different doses of antilonomic serum in the resolution of hemorrhagic syndrome resulting from envenoming by Lonomia obliqua caterpillars: a randomized controlled trial

The hemorrhagic syndrome caused by contact with Lonomia obliqua caterpillars has reached epidemic proportions in southern Brazil. This study aimed at assessing the efficacy of two different dosages of an antilonomic serum (SALon) in the treatment of patients who had accidental contact with L. obliqua caterpillars. A randomized, prospective controlled trial was conducted at São Vicente de Paulo Hospital, a tertiary hospital in Passo Fundo, Brazil. From January 2000 to April 2002, 44 patients with grade I or II hemorrhagic syndrome were randomly assigned to either group A: 22 patients treated with 10.5 mg total dose (three vials of SALon) or group B: 22 patients treated with 17.5 mg total dose (five vials of SALon). Treatment efficacy was assessed according to time necessary for blood coagulation to go back to normal, incidence of adverse reactions, and hospitalization time. There were no differences in clinical picture and laboratory findings between the two groups. Mean time for coagulation to go back to normal was 15.3+/-6.6 and 19.1+/-8 h in groups A and B, respectively. Adverse reactions and hospitalization time were similar in both groups. SALon was effective and well tolerated. This study demonstrated that three vials are as effective as five vials of SALon for the treatment of envenoming by Lonomia caterpillars.

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.

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.

Structures involved in production, secretion and injection of the venom produced by the caterpillar Lonomia obliqua (Lepidoptera, Saturniidae)

The number of accidents caused by injection of the venom of Lonomia obliqua caterpillars in Southern Brazil has increased in the last years. Even though this kind of envenomation has an important social and medical impact, nothing is known about the cellular structures responsible for the production and secretion of this venom. Here we identify and analyse morphological structures possibly responsible for the production and secretion of the active principles of the venom, as well as the histological relationship of these structures with the urticating spines of L. obliqua. Detailed microscopic observations showed that: (a) L. obliqua has a complex tegument, with several cuticular specializations, (b) there are no pores along the tegument neither in the spines and (c) the spines bear a hollow canal--where the venom is deposited--and an area that can be easily broken when touched, releasing the venom. Histological and histochemical techniques revealed that: (a) there is no single gland cell that produces the venom, (b) a secretory epithelium, composed of cells containing vesicles that increase in size and number as they reach the apical region, underlies the tegument and the spines and is responsible for secretion of the venomous substances and (c) the venom is deposited in the subcuticular space and at the tips of the spines.

In vivo characterization of Lopap, a prothrombin activator serine protease from the Lonomia obliqua caterpillar venom

Increasing occurrence of hemorrhagic syndrome in man, caused by contact with Lonomia obliqua caterpillars, has been reported in Southern Brazil in the past 10 years. The L. obliqua venom causes a severe consumptive coagulopathy, which can lead to hemorrhagic syndrome. L. obliqua prothrombin activator protease (Lopap) is a 69-kDa prothrombin activator serine protease isolated from L. obliqua caterpillar bristle extract, which is able to evoke thrombus formation, unclottable blood, and fibrinogen depletion when injected into the blood stream of rats. The purified protein generated thrombin from prothrombin, able to clot purified human fibrinogen and plasma. A decrease in platelet count and inhibition of collagen-induced platelet aggregation were observed, as well as leukocyte infiltration in the lungs. In addition, we observed congestion and hemorrhage in renal glomeruli and necrosis in renal distal tubules. These data support the hypothesis that Lopap contributes to the clinical syndrome caused by human contact with L. obliqua, most probably through prothrombin activation, resulting in a consumption coagulopathy.

Defibrinogenating enzymes

The venoms from 3 snakes have been shown to induce defibrinogenation: ancrod from the venom of Calloselasma rhodostoma (formerly known as Agkistrodon rhodostoma), batroxobin from the venom of Bothrops atrox moojeni, and crotalase from the venom of Crotalus adamanteus. The purified fractions of ancrod, batroxobin, and crotalase possess coagulant, proteolytic and esterolytic properties, although their primary mechanism of action is a proteolytic effect on circulating fibrinogen. Ancrod cleaves only the A-fibrinopeptides, but not the B-fibrinopeptides, from fibrinogen; this contrasts with thrombin, batroxobin and crotalase, which cleave both fibrinopeptides A and B. Within minutes of administration of ancrod or batroxobin, there is a significant reduction in plasma fibrinogen levels, and these remain exceedingly low with repeated administration (once or twice daily). The rapid fall in plasma fibrinogen levels is accompanied by a slightly delayed but marked rise in the level of fibrinogen-fibrin degradation products. Plasminogen levels are decreased and blood viscosity is reduced, but formed elements in the circulating blood remain unaltered. Ancrod and batroxobin have been investigated in patients with stroke, deep-vein thrombosis, myocardial infarction, peripheral arterial thrombosis, priapism, and sickle-cell crisis; crotalase has not been administered to humans. However, results have been difficult to interpret, and additional well designed trials are needed to better define the optimum role of ancrod and batroxobin in the management of these conditions. Overall, treatment is well tolerated and serious adverse events are infrequent. In the coagulation laboratory, ancrod, batroxobin and crotalase may be used as reagents to perform coagulation studies on specimens of blood that contain heparin. These venom fractions can be substituted for thrombin in performing the thrombin time and in removing fibrinogen from plasma for accurate determination of fibrinogen-fibrin degradation products.

Lonomia genus caterpillar toxins: biochemical aspects

In 1967 we reported for the first time five cases of an acquired bleeding disorder in humans which developed after contact with saturnidae caterpillars. Since that time, other cases have been reported in Brazil, French Guyana, Peru, Paraguay and Argentina. The caterpillars have been identified as Lonomia achelous (LA) in Venezuela and northern Brazil and as Lonomia obliqua (LO) in southern Brazil. All patients present pain and a burning sensation at the site of contact. Within a few hours hematomas and hematuria are seen in combination with intracerebral and intraperitoneal hemorrhage (in some cases also renal failure). Hematological tests show: mild anemia with leucocytosis; prolonged PT, PTT and ThT; decreased fibrinogen, factor V, factor XIII, plasminogen and alpha2-antiplasmin levels; increased factor VIII:c, von Willebrand factor, and FDPs/D-dimers levels with normal ATIII and platelets. Factor VII, factor II and PC levels varied. Several activities similar to or directed against blood clotting factors have been identified in LA: fibrinolytic enzymes, which degrade fibrinogen producing abnormal FDPs; prothrombin activators: one direct and one factor Xa-like; a thermostable factor V activator; a thermolabile factor V inhibitor; a factor XIII proteolytic/urokinase-like activity; and a kallikrein-like activitiy. In LO three activities have been described: a prothrombin activator called 'Lonomia obliqua prothrombin activator protease' (LOPAP); a factor X activator; and a phospholipase A(2)-like activity called Lonomiatoxin. No fibrinolytic activity has been described in LO. Subcutaneous injection of crude hemolymph and some chromatographic fractions of LA induce a decrease in fibrinogen, plasminogen and factor XIII. Intravenous injection of factor XIII proteolytic/urokinase-like activity induce a dose-dependent thrombolysis with a decrease in plasmatic factor XIII without hemorrhagic manifestations. Intradermal injection of LO bristle extracts in rats and rabbits produce incoagulability whereas intravenous injection of LOPAP induced DIC in mice.

The action of Lonomia achelous caterpillars venom on human factor V

The bleeding syndrome produced by contact with the Lonomia achelous caterpillars is characterized by a decrease of fibrinogen, factor XIII, plasminogen, and factor V with normal platelets. In this study, we report the effect of crude hemolymph and some semipurified chromatographic fractions on human factor V. Incubation of factor V with crude hemolymph resulted in an increase in procoagulant activity, followed by a subsequent decline in factor V activity. Identical results were obtained with fraction I, whereas with fraction II there was only a decrease in activity reaching its minimum at 30 minutes. fraction III did not modify the activity of factor V. All concentrations of fraction I tested produced an initial rise and subsequent fall in activity. However, at lower relative concentrations of fraction I, more sustained increases in activity were observed. The activator and inactivator activities present in fraction I show differences in temperature and pH stability, susceptibility to different inhibitors, and in SDS/PAGE pattern. The factor V activator is a thermostable protein, with maximum activity at acid pH and is inhibited by o-phenantroline, EDTA, and EGTA, while the factor V inactivator is thermolabile, presents maximum activity at basic pH, precipitates at pH 5.0, and is completely inhibited by iodoacetic acid and TLCK. It is partially blocked by diisopropyl fluorophosphate, phenylmethylsulfonyl fluoride, and p-chloromercuribenzoic acid. These results suggest that the activator should be a metallo-proteinase, while the inactivator is a serine or cysteine proteinase with a serine, histidine, or cysteine residue in the active site.

Fibrinolytic action on fresh human clots of whole body extracts and two semipurified fractions from Lonomia achelous caterpillar

The severe bleeding diathesis produced by intoxication with the venom of Lonomia achelous caterpillars is characterized by prolonged bleeding from superficial skin wounds as well as massive hemorrhage into body cavities. The aim of the present study was to evaluate the effect of the crude venom and its fibrinolytic fractions on in vitro lysis of whole blood clots. Venom fractions with fibrinolytic activity were obtained by gel filtration chromatography on Sephadex G75 using imidazole buffer, pH 7.4, at a flow rate of 24 ml/h. Four peaks with fibrinolytic activity were obtained by this method. The highest activity was found in the first two peaks (both peaks were used for the experiments). The results show that the caterpillar venom degraded the preformed clots at a slower rate than plasmin. In addition, plasma protease inhibitors of the fibrinolytic system (alpha 2-antiplasmin, alpha 2-macroglobulin, PAI, etc.) only weakly inhibited the lytic effect of the caterpillar venom. These characteristics, as well as the pattern of fibrinogen degradation products, the delay period on fibrin plate lysis and amidolytic activity on chromogenic substrate, reported previously, indicate that the caterpillar enzymes are different from plasmin and trypsin.

Hemorrhagic syndrome and acute renal failure in a pregnant woman after contact with Lonomia caterpillars: a case report

A case of a 37-week pregnant woman who developed a hemorrhagic syndrome and acute renal failure after contact with Lonomia caterpillars is reported. The accident also initiated labour and the patient gave birth to an alive child. Some pathophysiological aspects of the genital bleeding and of the acute renal failure are discussed.

Isolation and complete amino acid sequence of two fibrinolytic proteinases from the toxic Saturnid caterpillar Lonomia achelous

The major toxic and fibrinolytic activity of the saliva and hemolymph of the larval form of Lonomia achelous was purified to homogeneity by a combination of metal chelate and affinity chromatography. Two apparent isozymes, Achelase I (213 amino acids, pIcalc = 10.55) and Achelase II (214 amino acids, pIcalc = 8.51), were sequenced by automated Edman degradation, and their C-termini confirmed by Fourier-transform mass spectrometry. The calculated molecular weights (22,473 and 22,727) correspond well to Mr estimates of 24,000 by SDS-PAGE. No carbohydrate was detected during sequencing. The enzymes degraded all three chains of fibrin, alpha greater than beta much greater than gamma, yielding a fragmentation pattern indistinguishable from that produced by trypsin. Chromogenic peptides S-2222 (Factor Xa and trypsin), S-2251 (plasmin), S-2302 (kallikrein) and S-2444 (urokinase) were substrates while S-2288 (broad range of serine proteinases including thrombin) was not hydrolyzed. Among a range of inhibitors Hg+2, aminophenylmercuriacetate, leupeptin, antipain and E-64 but not N-ethylmaleimide or iodoacetate abolished the activity of the purified isozymes against S-2444. Phenylmethylsulfonyl fluoride, soybean trypsin inhibitor and aprotinin were less effective. The presence of the classic catalytic triad (histidine-41, aspartate-86 and serine-189) suggests that Achelases I and II may be serine proteinases, but with a potentially free cysteine-185 which could react with thiol proteinase-directed reagents.