Activation of human prothrombin by the venom of Lonomia achelous (Cramer) caterpillars

Contribution of endothelial cell and macrophage activation in the alterations induced by the venom of Micrurus tener tener in C57BL/6 mice

An acute inflammatory response, cellular infiltrates, anemia, hemorrhage and endogenous fibrinolysis activation were previously described in C57BL/6 mice injected with M. tener tener venom (Mtt). As the endothelium and innate immunity may participate in these disturbances and due to our poor understanding of the alterations produced by these venoms when the neurotoxic component is not predominant, we evaluated the effects in an in vitro model. At 24 h, the release of pro-inflammatory mediators was detected in peritoneal macrophages. At different times, the release of pro-inflammatory (TNF-α, IL-6, NO and E-Selectin), pro-coagulant (vWF and TF) and pro-fibrinolytic (uPA) mediators were seen in liver sinusoidal endothelial cells (LSECs). These results suggest that Mtt venom activates macrophages and endothelium, thus inducing the release of mediators, such as TNF-α, that orchestrate the acute inflammatory response and the later infiltration of mononuclear cells into liver in C57BL/6 mice. In addition, endothelium activation promotes TF expression, which may in turn modulate the inflammatory and hemostatic response. These findings suggest crosstalk between inflammation and hemostasis in the alterations observed in Micrurus envenomation, where the neurotoxic manifestations do not predominate.

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.

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.

Browplasminin, a condensed tannin with anti-plasmin activity isolated from an aqueous extract of Brownea grandiceps Jacq. flowers

ETHNOPHARMACOLOGICAL RELEVANCE

Following Venezuelan traditional medicine, females with heavy menstrual blood loss (menorrhagia) drink Brownea grandiceps Jacq. flowers (BG) decoctions to reduce the bleeding. In a previous study, we demonstrated that BG aqueous extract (E) possesses a potent anti-fibrinolytic activity capable of inhibiting plasmin, the main serine-protease that degrades fibrin. It is widely known that plasmin inhibitors are often used as anti-fibrinolytics to reduce bleeding during surgeries with high risk of blood loss such as cardiac, liver, vascular, tooth extraction and large orthopedic procedures, as well as for menorrhagia treatments. The aim of this work was to isolate and characterize from BGE the compound responsible for the reported anti-fibrinolytic activity.

MATERIALS AND METHODS

A decoction of BG was prepared; then it was homogenized, centrifuged and lyophilized to obtain BGE. Subsequently the extract was fractionated by gel filtration and reverse phase using HPLC and the active compound was characterized by MALDI-ToF MS. The kinetic parameters of anti-plasmin activity were evaluated by an amidolytic assay using a chromogenic substrate; also the anti-plasmin activity was estimated by fibrin plate method. Data were analyzed by nonparametric statistics.

RESULTS

The active compound was a condensed tannin denominated Browplasminin, which is capable of inhibiting the plasmin activity in a dose-dependent manner when measured in fibrin plates or by the amidolytic activity method; it also has a minor effect on the FXa activity. However, it does not affect the activity of other serine-proteases such as trypsin, t-PA or u-PA. Browplasminin consists predominately of heteroflavan-3-ols of catechin with B-type linkages, and extents up to heptadecamers (~ 5000Da), with hexose residues attached to the polymer that presents a high degree of galloylation. Its IC₅₀ for plasmin was 47.80μg/mL and for FXa was 237.08μg/mL, while the Ki were 0.76 and 61.61μg/mL for plasmin and FXa, respectively.

CONCLUSIONS

The overall outcome of this study suggests that Browplasminin could be responsible for reducing heavy menstrual bleeding in women because its kinetic parameters showed that is a good plasmin inhibitor.

Aqueous extract from Brownea grandiceps flowers with effect on coagulation and fibrinolytic system

ETHNOPHARMACOLOGICAL RELEVANCE

Brownea grandiceps flowers are used in Venezuelan folk medicine as anti-hemorrhagic in women with heavy menstrual blood loss (menorrhagia). However, prior to this study, there were no scientific investigations to support this fact, because the aqueous extract from Brownea grandiceps flowers had not been previously evaluated neither phytochemically nor biologically. The objective of this work was to evaluate in vitro the effects of aqueous extract from Brownea grandiceps flowers on the coagulation system and fibrinolysis.

MATERIALS AND METHODS

An infusion of Brownea grandiceps flowers (160g) was performed; then, it was homogenized, centrifuged and lyophilized to obtain the aqueous extract, and this was called BGE. Subsequently, the extract was characterized on the one hand, phytochemically and on the other hand, biologically, employing prothrombin time (PT), partial thromboplastin time (PTT) and thrombin time (TT) to determine the effects on extrinsic, intrinsic and common coagulation pathways, respectively. In addition to that, the fibrinogenolytic and fibronectinase activity was evaluated by SDS-PAGE using Tris-Tricine system and analyzed by densitometric study utilizing ImageJ program. Also, by using specific chromogenic substrates for Factor Xa (FXa), thrombin, tissue plasminogen activator (t-PA), urokinase plasminogen activator (u-PA) and plasmin, it was assessed whether BGE exhibited some enzyme-like activity, and inhibitory activity of the afore mentioned enzymes. Fibrinolytic and antifibrinolytic activities were determined by a fibrin plate method. Data were analyzed by an nonparametric method.

RESULTS

BGE presented tannins, saponins, glycosides, alkaloids, flavonoids, coumarins, and did not contain triterpenoids and steroids. Also, BGE at low concentrations (250-1250µg/mL) reduced the PT, while higher concentrations (15000-25000µg/mL) prolonged this time. However, BGE concentrations between 1250 and 25000µg/mL prolonged the PTT. Prolongation of PT and PTT was observed at high concentrations and was due to FXa inhibitor found in BGE and this effect could be strengthened by degradation of fibrinogen and fibronectin, which were also produced by BGE. Moreover, BGE did not clot fibrinogen or human plasma, and neither did it cleave the chromogenic substrates specific to FXa nor thrombin. These results suggest the pro-coagulant components could be acting on some factor of the extrinsic pathway, since only PT was shortened. Furthermore, BGE did not hydrolyze the chromogenic substrate specific to plasmin, t-PA and u-PA nor did it produce fibrin degradation. However, all BGE concentrations tested inhibited the plasmin activity in a dose-dependent manner.

CONCLUSIONS

The outcomes of this study reveal the presence of fibrinogenolytic, fibronectinase and anti-FXa components in BGE, plus anti-plasmin compounds that could be acting as antifibrinolytic, thus delaying the fibrin degradation in pathophysiological processes, as it has been observed in women presenting with menorrhagia due to a high plasmin concentration. Where this anti-plasmin compound, along with pro-coagulant components also present in BGE, could be made responsible for reducing heavy menstrual bleeding in women, since a deficiency in one or more blood coagulation factors such as factor VII, V or X, is a potential cause of menorrhagia.

Studies on bioprospecting potential of a gastropod mollusc Cantharus tranquebaricus (Gmelin, 1791)

OBJECTIVE

To study the biological activities of the tissue extract of Cantharus tranquebaricus (C. tranquebaricus).

METHODS

Crude extract of gastropod was tested for inhibition of bacterial growth. Antibacterial assay was carried out by disc diffusion method and the activity was measured accordingly based on the inhibition zone around the disc impregnated with gastropod extract. Molecular weight of the extract was determined by using SDS-PAGE. Plasma coagulation, Fibrin plate assay and substrate SDS-PAGE were used to determine the effect of sample on plasma coagulation, fibrin (ogen) olytic and proteolytic activity.

RESULTS

The maximum inhibition zone (10 mm) was observed against Vibrio cholera (V. cholera) and minimum inhibition zone (2 mm) was noticed against Proteus mirablis (P. mirablis). The molecular weight was determined as 47-106 kDa. The tissue extract shows proteolytic activity above 48 kDa. SDS-PAGE analysis of fibrinogen after incubation with the tissue extract showed fibrinogenolytic activity. In plasma coagulation assay C. tranquebaricus tissue extract showed procoagulant property and it coagulated chicken plasma within 150 s, while control took 5 min to clot. The 9 HU hemolytic units were found against chicken blood and also exhibit high level of brine shrimp lethality.

CONCLUSIONS

This study suggests that C. tranquebaricus could be used as potential source for isolating bioactive compounds, since it is explored first time and found with promising results.

Isolation and characterization of two new non-hemorrhagic metalloproteinases with fibrinogenolytic activity from the mapanare (Bothrops colombiensis) venom

Colombienases are acidic, low molecular weight metalloproteinases (Mr of 23,074.31 Da colombienase-1 and 23,078.80 Da colombienase-2; pI of 6.0 and 6.2, respectively) isolated from Bothrops colombiensis snake venom. The chromatographic profile in RP-HPLC and its partial sequence confirmed its high homogeneity. Both colombienases present fibrino(geno)lytic activity, but did not show any hemorrhagic, amidolytic, plasminogen activator or coagulant activities, and no effect on platelet aggregation induced by collagen or ADP. Both enzymes were strongly active on fibrinogen Aα chains followed by the Bβ chains, and colombienases-2, at high doses, also degraded the γ chains. This activity was stable at temperatures ranging between 4 and 37 °C, with a maximum activity at 25 °C, and at pHs between 7 and 9. The homology demonstrated by the comparison of sequences, with zinc-dependent metalloproteinases, as well as the metal chelant effects on, confirmed that the colombienases were metalloproteinases, particularly to α-fibrinogenases belonging to the P-I class of SVPMs (20-30 kDa), which contain only the single-domain proteins. The biological characteristics of the colombienases confer a therapeutic potential, since they contain a high fibrino(geno)lytic activity, devoid of hemorrhagic activity. These metalloproteinases might be explored as thrombolytic agents given that they dissolve fibrin clots or prevent their formation.

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.

Hemostatic and toxinological diversities in venom of Micrurus tener tener, Micrurus fulvius fulvius and Micrurus isozonus coral snakes

The coral snake Micrurus tener tener (Mtt) from the Elapidae family inhabits the southwestern United States and produces severe cases of envenomations. Although the majority of Mtt venom components are neurotoxins and phospholipase A₂s, this study demonstrated, by SDS-PAGE and molecular exclusion chromatography (MEC), that these venoms also contain high-molecular-weight proteins between 50 and 150 kDa that target the hemostatic system. The biological aspects of other Micrurus venoms were also studied, such as the LD₅₀s of Micrurus isozonus (from 0.52 to 0.61 mg/kg). A pool from these venoms presented a LD₅₀ of 0.57 mg/kg, Micrurus f. fulvius (Mff) and Mtt had LD₅₀s of 0.32 and 0.78 mg/kg, respectively. These venoms contained fibrino(geno)lytic activity, they inhibited platelet aggregation, as well as factor Xa and/or plasmin-like activities. M. isozonus venoms from different Venezuelan geographical regions inhibited ADP-induced platelet aggregation (from 50 to 68%). Micrurus tener tener venom from the United States was the most active with a 95.2% inhibitory effect. This venom showed thrombin-like activity on fibrinogen and human plasma. Fractions of Mtt showed fibrino(geno)lytic activity and inhibition on plasmin amidolytic activity. Several fractions degraded the fibrinogen Aα chains, and fractions F2 and F7 completely degraded both fibrinogen Aα and Bβ chains. To our knowledge, this is the first report on thrombin-like and fibrino(geno)lytic activity and plasmin or factor Xa inhibitors described in Micrurus venoms. Further purification and characterization of these Micrurus venom components could be of therapeutic use in the treatment of hemostatic disorders.

Activities against hemostatic proteins and adrenal gland ultrastructural changes caused by the brown widow spider Latrodectus geometricus (Araneae: Theridiidae) venom

Brown widow spider (BrWS) (Latrodectus geometricus) venom produces intense systemic reactions such as cramps, harsh muscle nociceptive, nauseas, vomiting and hypertension. The proposed pathogenic mechanisms resulting in these accidents have principally been damages occurring at the nervous system. However, it is suspected that there is also damage of the adrenal glands, as a result of the experimental animal's clinical manifestations, which developed symptoms compatible with acute adrenal insufficiency. We have currently found that the adrenal gland is damaged by this venom gland homogenates (VGH) producing severe alterations on cortex cells resulting in death by acute adrenal insufficiency. In general, the ultrastructural study on the glands of mice under transmission electronic microscopy observations showed alterations in the majority of the intracellular membranes within 3 to 24h. BrWSVGH also showed specific actions on extracellular matrix proteins such as fibronectin, laminin and fibrinogen. In addition, zymogram experiments using gelatin as substrates detected gelatinolytic activity. The molecular exclusion fractionation of crude BrWSVGH resulted in 15 fractions, of which F1 and F2 presented alpha/beta-fibrinogenase and fibronectinolytic activities. Fractions F6, F14 and F15 showed only alpha-fibrinogenase activity; in contrast, the gelatinolytic action was only observed in fraction F11. Only metalloproteinase inhibitors abolished all these proteolytic activities. Our results suggest that adrenal cortex lesions may be relevant in the etiopathogenesis of severe brown widow spider envenoming. To our knowledge, this is the first report on adrenal gland damages, fibrinogenolytic activity and interrelations with cell-matrix adhesion proteins caused by L.geometricus VGH. The venom of this spider could be inducing hemostatic system damages on envenomed patients.

Venom variation in hemostasis of the southern Pacific rattlesnake (Crotalus oreganus helleri): isolation of hellerase

Envenomations by the southern Pacific rattlesnake (Crotalus oreganus helleri) are the most common snakebite accidents in southern California. Intraspecies venom variation may lead to unresponsiveness to antivenom therapy. Even in a known species, venom toxins are recognized as diverse in conformity with interpopulational, seasonal, ontogenetic and individual factors. Five venoms of individual C. oreganus helleri located in Riverside and San Bernardino counties of southern California were studied for their variation in their hemostatic activity. The results demonstrated that Riverside 2 and San Bernardino 1 venoms presented the highest lethal activity without hemorrhagic activity. In contrast, San Bernardino 2 and 3 venoms had the highest hemorrhagic and fibrinolytic activities with low lethal and coagulant activities. Riverside 1, Riverside 2 and San Bernardino 1 venoms presented a significant thrombin-like activity. San Bernardino 2 and 3 venoms presented an insignificant thrombin-like activity. In relation to the fibrinolytic activity, San Bernardino 3 venom was the most active on fibrin plates, which was in turn neutralized by metal chelating inhibitors. These results demonstrate the differences amongst C. oreganus helleri venoms from close localities. A metalloproteinase, hellerase, was purified by anionic and cationic exchange chromatographies from San Bernardino 3 venom. Hellerase exhibited the ability to break fibrin clots in vitro, which can be of biomedically importance in the treatment of heart attacks and strokes.

Intraspecies differences in hemostatic venom activities of the South American rattlesnakes, Crotalus durissus cumanensis, as revealed by a range of protease inhibitors

Crotalus durissus cumanensis is an endemic rattlesnake found in Venezuela and Colombia. In this study, a comparative analysis of hemorrhagic, coagulation and fibrino(geno)lytic activities in the presence or absence of protease inhibitors was performed with venoms of the same species Crotalus durissus cumanensis, from seven geographical regions of Venezuela (Lagunetica, Santa Teresa, Carrizales, Guarenas, Anzoátegui, Margarita and Maracay). Lagunetica, Carrizales and Anzoátegui venoms induced hemorrhagic activity. All venoms, except that of snakes from the Carrizales region presented thrombin-like activity, which was inhibited completely by phenylmethanesulfonyl fluoride and ethylene glycol-bis-N, N,N',N'-tetraacetic acid. This effect of the latter could be explained by the high chelant calcium effect, which is a cofactor for the fibrin polymerization process. Soybean trypsin inhibitor was effective on Santa Teresa venom. Antithrombin III/Hep complex and phenantroline partially inhibited this activity in all venoms except Margarita and Anzoátegui, respectively, which were not inhibited. Serine protease inhibitors were more effective against thrombin, kallikrein and plasmin-like amidolytic activities. Additionally, metalloprotease inhibitors significantly inhibited the t-PA-like amidolytic activity and completely the hemorrhagic and fibrino(geno)lytic activities. In conclusion, the thrombin-like activity observed in these venoms was partially reduced by serine protease inhibitors, indicating the possible presence of catalytic domains in those enzymes that do not interact with these inhibitors. Using protease inhibitors on venom hemostatic activities could contribute to our understanding of the active components of snake venom on the hemostatic system, and further reveal the intraspecies variation of venoms, which is important in the treatment of envenomation, and in addition represents an interesting model for the study of venom in hemostasis.

Discreplasminin, a plasmin inhibitor isolated from Tityus discrepans scorpion venom

Tityus discrepans venom (TdV) produces digestive hemorrhages, disseminated intravascular coagulation, alveoli fibrin deposition and/or prothrombin and partial thromboplastin time alterations in humans. T. discrepans venom presents an in vitro tissue plasminogen activator-like (tPA-like), fibrino(geno)lytic and plasmin inhibitory activities. The plasmin inhibitor, called discreplasminin, was isolated from TdV. Discreplasminin has a pI of 8.0 and a relative molecular weight of <6,000 Da. Discreplasminin and aprotinin strongly inhibited plasmin activity and moderately tPA activity, while epsilon amino caproic acid (EACA) moderately inhibited both enzymes. In presence and absence of fibrin, the plasmin generation by tPA was completely inhibited by aprotinin and discreplasminin. EACA in the absence of fibrin partially inhibited plasmin generation (37%); however, it produced a total inhibition of plasmin generation on a fibrin surface. The tPA-clot lysis assay showed that discreplasminin acts like aprotinin inducing a slight delay in lysis time and lysis rate; in contrast, EACA presented a total inhibitory effect on fibrin lysis. These results suggest that discreplasminin presents an anti-fibrinolytic mechanism similar to aprotinin. Discreplasminin probably interacts with the active sites of plasmin and tPA. The presence of discreplasminin and other similar components in scorpion venom could partially explain the generalized fibrin deposition which was found previously in rams.

Anti-platelet effect of cumanastatin 1, a disintegrin isolated from venom of South American Crotalus rattlesnake

Disintegrins have been previously described in the venom of several snake families inhibiting signal transduction, cell-cell interactions, and cell-matrix interactions and may have therapeutic potential in heart attacks, thrombotic diseases, and cancers. This investigation describes the first disintegrin isolated from South American Crotalus venom (Venezuelan rattlesnake Crotalus durissus cumanensis), which inhibits platelet adhesion to matrix proteins. C. d. cumanensis crude venom was first separated on a Sephadex G-100 column into 4 fractions (SI to SIV). Crude venom and SIII fraction significantly diminished platelet adhesion to fibrinogen (Fg) and to fibronectin (Fn). Anti-adhesive SIII fraction was further separated by DEAE-Sephacel followed by C-18 reverse phase high performance liquid chromatography (HPLC). The platelet anti-adhesive fraction obtained was designated as cumanastatin-1. This disintegrin has a mass of 7.442 kDa as determined by mass spectrometry (MALDI-TOF/TOF) and pI of 8.5. Cumanastatin-1 also inhibited ADP-induced platelet aggregation with an IC(50) of 158 nM. However, it did not significantly inhibit collagen and thrombin-induced platelet aggregation. Cumanastatin-1 considerably inhibited anti-alpha(IIb)beta(3) integrin binding to platelets in a dose-dependent manner; however, it did not present any effect on the alpha(5)beta(1) integrin or on P-selectin.

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.

Individual venom variability in the South American rattlesnake Crotalus durissus cumanensis

Crotalus durissus cumanensis snake venoms from different Venezuelan regions, showed biochemical and hemostatic variations. Fibrino(geno)lytic, hemorrhagic and procoagulant activities and gel-filtration chromatography and SDS-PAGE profiles were analyzed. Differences were observed in fibrinolytic activity: kallikrein-like amidolytic activity was highest in venoms of Santa Teresa, and Margarita. Lagunetica and Carrizales venoms showed the maximum fibrin lysis. The highest hemorrhagic activity was seen in Lagunetica venom. Margarita had the lowest LD(50) of 0.18. Lagunetica, Carrizales and Anzoátegui induced a rapid degradation of fibrinogen alpha chains and slower degradation on beta chains, which could possibly due to a higher content of alpha fibrinogenases in these venoms. This fibrinogenolytic activity is decreased by metalloprotease inhibitors. All venoms, except Carrizales, presented thrombin-like activity. Anzoátegui, Carrizales and Lagunetica, in which fibrinolytic activity was present, showed the largest concentration of high molecular mass components. These results represent a new finding, not previously described, of fibrinolytic activity in South American C. durissus venoms. Santa Teresa and Margarita had fibrinolytic activity, and lack of hemorrhagic activity, representing an important finding in Venezuelan venoms since the description of a fibrinolytic molecule without hemorrhagic activity can have valuable potential in thrombolytic therapy.

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.

Identification and partial characterisation of hyaluronidases in Lonomia obliqua venom

By studying Lonomia obliqua (caterpillar) venom we were able to detect a lytic activity on purified hyaluronic acid. The venom hydrolyses purified chondroitin sulphate, but was unable to degrade either heparan sulphate or dermatan sulphate. Moreover, through purified hyaluronic acid-degrading kinetic assays, we observed that this lytic activity was caused by a hydrolase rather than lyase enzyme. In addition, by using the Reissig colorimetric reaction, we detected this hyaluronic acid hydrolase action as a beta-endohexosaminidase enzyme originating terminal N-acetylglucosamine residues rather than beta-endoglucuronidase, which may originate glucuronic acid residues. Zymogram analysis of the venom detected 49 and 53 kDa molecules with hyaluronic acid lytic activity. An examination of these hyaluronic acid degrading activities as a function of pH showed that these hydrolases had no apparent activities at a pH below 5.0 and higher than 8.0 and displayed their optimal activities at pH ranging from 6.0 to 7.0. Finally, through a fluorescence reaction to hyaluronic acid and confocal microscopy, we confirmed this cleaving action upon hyaluronic acid organised on the extracellular matrix of the dermis of rabbit. The data provide experimental evidence of the presence of hyaluronidases in the L. obliqua venom, probably involved in the harmful effects of the venom.

[Lonomia erucism in Teresópolis, Rio de Janeiro State, Brazil: report of a probable case and review]

This is a case report of a 44-year-old male living in Teresópolis, RJ, Brazil, probably poisoned by contact with a Lonomia caterpillar, who presented hemolytic anemia, decreased platelet count and acute renal insufficiency. Lonomia erucism diagnosis was established by anamnesis and clinical and laboratory manifestations. Therapeutic measures consisting of hemotransfusion and hemodialysis were successful. Physiopathologic and clinical features of erucism by Lonomia are discussed.

Fibrinogenolytic and procoagulant activities in the hemorrhagic syndrome caused by Lonomia obliqua caterpillars

The hemorrhagic syndrome caused by accidents with caterpillars of the genus Lonomia has been the focus of several clinical and biochemical studies, since its venom is composed of many active principles that interfere with the hemostatic system. Whereas a fibrinolytic agent has been characterized in the venom of Lonomia achelous, in Lonomia obliqua, only a prothrombin activator activity has been reported so far, even though both species cause similar bleeding disorders, characterized by hemorrhage, disseminated intravascular coagulation (DIC), and acute renal failure. Considering the possibility that the hemorrhagic syndrome resulting from envenoming by L. obliqua may be due to fibrinolytic and procoagulant activities acting together, we decided to investigate the effects of bristle extract (BE) of this species upon blood coagulation and fibrin(ogen)olysis. This study shows that besides a procoagulant activity related to the activation of prothrombin, the venom contains at least one fibrin(ogen)olytic activity, as shown by fibrinolysis in a fibrin (F) plate assay, by interference in thrombin-catalyzed fibrinocoagulation, and by polyacrylamide gel electrophoresis profile of fibrin and fibrinogen (Fg) degradation. Considering that a recombinant prothrombin activator from L. obliqua has been suggested in other studies to be used as an anti-thrombotic agent, it is important in the first place to better characterize the different active principles of this venom.

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.

A prothrombin activator serine protease from the Lonomia obliqua caterpillar venom (Lopap) biochemical characterization

Lonomia obliqua venom causes a severe consumptive coagulopathy, which can lead to a hemorrhagic syndrome. The crude bristles extract displays a procoagulant activity due to a Factor X and to a prothrombin activating activity. Here, we describe a 69 kDa prothrombin activator serine protease purified from L. obliqua caterpillar bristle extract using gel filtration (Sephadex G 75) and HPLC (C(4) column). The purified protein was able to activate prothrombin in a dose-dependent manner, and calcium ions increased this activity. The prothrombin-derived fluorogenic peptide (Abz-YQTFFNPRTGSQ-EDDnp) had its main cleavage site at the Arg-Thr bond. The kinetic parameters obtained for this substrate were Kmapp of 4.5 microM, kcat of 5.32 s(-1), and a kcat/Kmapp of 1.2 x 10(6) M(-1) s(-1). The prothrombin fragments generated by the purified enzyme corresponded to the molecular masses of prethrombin 2, fragment 1, fragment 2, and thrombin as seen in SDS-PAGE. The thrombin generated was able to clot purified fibrinogen. The partial amino acid sequence of the purified protein, named Lopap (L. obliqua prothrombin activator protease), showed no similarity to any known prothrombin activator.

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.

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.

The action of Lonomia achelous caterpillar venom on some blood coagulation and fibrinolysis parameters of the rabbit

The bodily secretions of the Lonomia achelous caterpillar cause a severe and often fatal acquired bleeding diathesis in humans. The rabbit was selected as model animal in an attempt to understand the mode of action of the venom. The animals were injected subcutaneously with either hemolymph or chromatographically purified fractions. Injections of hemolymph produced a drop in fibrinogen and factor XIII levels and an increase in fibrinogen degradation products (FDP). In addition one batch of hemolymph decreased plasminogen levels. The chromatographically semipurified fraction II decreased both fibrinogen and plasminogen. The effect was dose dependent but, unlike in humans, there was a fairly rapid return to baseline values. In conclusion, the response to Lonomia achelous venom in the rabbit is similar to the response seen in humans, but with a more rapid recovery.

Effect on platelet FXIII and partial characterization of Lonomin V, a proteolytic enzyme from Lonomia achelous caterpillars

Contact with Lonomia achelous caterpillars venom induces a severe bleeding syndrome in humans. A constant finding in all reported cases is a marked decrease of blood coagulation factor XIII (FXIII), which has been attributed to the presence of a proteolytic enzyme, isolated and named Lonomin V, in the hemolymph and hair secretion. In this study, the effect of Lonomin V on transglutaminase activity from human plasma, rabbit plasma, and platelet FXIII was analyzed. The decrease of activity was more pronounced in platelet (A2) when compared with rabbit plasma (AB) and human plasma FXIII (A2B2). This finding might be explained by the differences in FXIII molecular structure. In addition, platelet FXIII molecule was degraded by Lonomin to several fragments of low molecular mass. Lonomin V was stable over a wide range of pH (6-8.5) and temperatures of -70 degrees C, -20 degrees C and between 4 to 24 degrees C, with a progressive decrease at 37 degrees C and total inactivation at 60 degrees C after 2 hours incubation. Diisopropyl fluoro-phosphate, phenylmethylsulfonyl fluoride, tosyl-l-lysine chloromethyl ketone, and iodoacetamide abolished the effect of Lonomin V on FXIII; in contrast dithiothreitol and EDTA-Na enhance the activity. We concluded that Lonomin V is a serine proteinase with a free Cys essential for the enzymatic activity. Due to its proteolytic activity on FXIII, with concomitant impairment of fibrin cross-linking, Lonomin V might be useful in association with thrombolytic drugs for preventing rethrombosis.

Degradation of human factor XIII by lonomin V, a purified fraction of Lonomia achelous caterpillar venom

Lonomia achelous caterpillar venom (LACV) causes a severe bleeding diathesis in humans. A constant finding in these cases is a profound depression of blood clotting Factor XIII (FXIII) activity. The molecular mechanisms by which LONOMIN V (a chromatographically purified fraction from LACV) alters the FXIII complex is the subject of the present study. Incubation of human purified FXIII with Lonomin V shows that both the zymogen and the activated forms of FXIII were proteolytically degraded, with the generation of peptidic fragments of low molecular weight. Both the A and B subunits of FXIII were degraded in a progressive, dose dependent manner. The B subunit was more resistant to the action of Lonomin V, requiring higher concentrations in order to achieve complete degradation. On the basis of these findings we postulate that the proteolysis of FXIII in vivo is one of the pathophysiological factors behind this bleeding syndrome.