Neutralization of the oedematogenic activity of Bothrops jararaca venom on the mouse paw by an antibothropic fraction isolated from opossum (Didelphis marsupialis) serum

Understanding Local Reactions Induced by Bothrops jararaca Venom: The Role of Inflammatory Mediators in Leukocyte-Endothelium Interactions

In recent years, extensive research has delved into the pathophysiology of local reactions triggered by Bothrops snake venoms. Even though antivenom works well at reducing death and systemic effects, it is still not very effective in treating local reactions because it cannot counteract damage that has already been triggered. This limitation might be attributed to certain molecules that amplify the venom-induced innate response. While evidence suggests endogenous mediators at the venom site play a role in this envenomation, in Brazil, the concurrent use of anti-inflammatory agents or other drugs alongside antivenom remains uncommon. This study evaluated the pharmacological mediation of alterations in leukocyte-endothelium interactions following the experimental envenomation of mice with Bothrops jararaca venom, the main culprit of snake-related accidents in Southeast Brazil. We treated envenomed mice with inhibitors of different pharmacological pathways and observed the cremaster muscle microcirculation with intravital microscopy. We found that eicosanoids related to cyclooxygenase pathways and nitric oxide significantly contributed to B. jararaca venom-induced alterations in leukocyte-endothelium interactions. Conversely, lipoxygenase-mediated eicosanoids, histamine, and serotonin had minimal participation. Notably, dexamethasone and antivenom treatment diminished B. jararaca venom-induced alterations in leukocyte-endothelium interactions. The limited efficacy of the antivenom in managing Bothrops venom-induced local reactions emphasizes the critical need for supplementary treatments to enhance therapeutic outcomes.

Pain modulated by Bothrops snake venoms: Mechanisms of nociceptive signaling and therapeutic perspectives

Snake venoms are substances mostly composed by proteins and peptides with high biological activity. Local and systemic effects culminate in clinical manifestations induced by these substances. Pain is the most uncomfortable condition, but it has not been well investigated. This review discusses Bothrops snakebite-induced nociception, highlighting molecules involved in the mediation of this process and perspectives in treatment of pain induced by Bothrops snake venoms (B. alternatus, B. asper, B. atrox, B. insularis, B. jararaca, B. pirajai, B. jararacussu, B. lanceolatus, B. leucurus, B. mattogrossensis, B. moojeni). We highlight, the understanding of the nociceptive signaling, especially in snakebite, enables more efficient treatment approaches. Finally, future perspectives for pain treatment concerning snakebite patients are discussed.

An overview of Bothrops erythromelas venom

This review discusses studies on the venom of Bothrops erythromelas published over the past 36 years. During this period, many contributions have been made to understand the venomous snake, its venom, and its experimental and clinical effects better. The following chronological overview is based on 29 articles that were published between 1979 and 2015, with emphasis on diverse areas. The complexity of this task demands an integration of multidisciplinary research tools to study toxinology. This science is in need of renewed conceptual and experimental platforms aimed at obtaining a profound understanding of the highly complex pathophysiology of snakebite envenoming and toxins isolated from snakes.

Edema and Nociception Induced by Philodryas patagoniensis Venom in Mice: A Pharmacological Evaluation with Implications for the Accident Treatment

We have investigated the mechanisms involved in the genesis of edema and nociception induced by Philodryas patagoniensis venom (PpV) injected into the footpad of mice. PpV induced dose-related edema and nociceptive effects. Pretreatment of mice with cyclooxygenase inhibitor (indomethacin), but not with cyclooxygenase 2 inhibitor (celecoxib) markedly inhibited both effects. Pretreatments with H₁ receptor antagonist (promethazine) or with dual histamine-serotonin inhibitor (cyproheptadine) failed in inhibiting both effects. In groups pretreated with captopril (angiotensin-converting enzyme inhibitor) the edema was unaltered, but nociception was clearly increased, suggesting the participation of kinins in the pathophysiology of the nociception but not of the edema-forming effect of PpV. When PpV was treated with EDTA, the nociception was similar to the one induced by untreated venom, but edema was markedly reduced. We concluded that PpV-induced edema and nociception have cyclooxygenase eicosanoids as the main mediators and no participation of vasoactive amines. Kinins seem to participate in nociception but not in edema induced by PpV. The results also suggest that metalloproteinases are the main compounds responsible for the edema, but not for the nociception induced by this venom.

Experimental Bothrops atrox envenomation: Efficacy of antivenom therapy and the combination of Bothrops antivenom with dexamethasone

Bothrops atrox snakes are the leading cause of snake bites in Northern Brazil. The venom of this snake is not included in the antigen pool used to obtain the Bothrops antivenom. There are discrepancies in reports on the effectiveness of this antivenom to treat victims bitten by B. atrox snakes. However, these studies were performed using a pre-incubation of the venom with the antivenom and, thus, did not simulate a true case of envenomation treatment. In addition, the local lesions induced by Bothrops venoms are not well resolved by antivenom therapy. Here, we investigated the efficacy of the Bothrops antivenom in treating the signs and symptoms caused by B. atrox venom in mice and evaluated whether the combination of dexamethasone and antivenom therapy enhanced the healing of local lesions induced by this envenomation. In animals that were administered the antivenom 10 minutes after the envenomation, we observed an important reduction of edema, dermonecrosis, and myonecrosis. When the antivenom was given 45 minutes after the envenomation, the edema and myonecrosis were reduced, and the fibrinogen levels and platelet counts were restored. The groups treated with the combination of antivenom and dexamethasone had an enhanced decrease in edema and a faster recovery of the damaged skeletal muscle. Our results show that Bothrops antivenom effectively treats the envenomation caused by Bothrops atrox and that the use of dexamethasone as an adjunct to the antivenom therapy could be useful to improve the treatment of local symptoms observed in envenomation caused by Bothrops snakes.

Bothrops atrox is the dominant species responsible for accidental human snake bites in Northern Brazil. The efficacy of antivenom therapy to correct the systemic disturbances, including hemostatic disorders, caused by Brazilian Bothrops is well known. However, two fundamental issues need to be addressed in this region. (1) There are concerns regarding the effectiveness of the antivenom to treat Bothrops snake bites in this region since Bothrops atrox venom is not used as an antigen to obtain the Bothrops antivenom in Brazil, and (2) the efficacy of the antivenom therapy in reversing local injuries induced by Bothrops venoms is low. Thus, our study aimed to assess the effectiveness of antivenom therapy alone or in combination with dexamethasone to treat experimental envenomation induced by Bothrops atrox venom in mice. Our results showed that the Brazilian Bothrops antivenom effectively reversed the systemic disturbances caused by this envenomation and combining the antivenom therapy with dexamethasone accelerated the regression of inflammatory edema and the regeneration of skeletal muscle that was damaged by the venom.

Natural Inhibitors of Snake Venom Metalloendopeptidases: History and Current Challenges

The research on natural snake venom metalloendopeptidase inhibitors (SVMPIs) began in the 18th century with the pioneering work of Fontana on the resistance that vipers exhibited to their own venom. During the past 40 years, SVMPIs have been isolated mainly from the sera of resistant animals, and characterized to different extents. They are acidic oligomeric glycoproteins that remain biologically active over a wide range of pH and temperature values. Based on primary structure determination, mammalian plasmatic SVMPIs are classified as members of the immunoglobulin (Ig) supergene protein family, while the one isolated from muscle belongs to the ficolin/opsonin P35 family. On the other hand, SVMPIs from snake plasma have been placed in the cystatin superfamily. These natural antitoxins constitute the first line of defense against snake venoms, inhibiting the catalytic activities of snake venom metalloendopeptidases through the establishment of high-affinity, non-covalent interactions. This review presents a historical account of the field of natural resistance, summarizing its main discoveries and current challenges, which are mostly related to the limitations that preclude three-dimensional structural determinations of these inhibitors using “gold-standard” methods; perspectives on how to circumvent such limitations are presented. Potential applications of these SVMPIs in medicine are also highlighted.

Inflammatory mediators involved in the paw edema and hyperalgesia induced by Batroxase, a metalloproteinase isolated from Bothrops atrox snake venom

Snake venom metalloproteinases have been described as responsible for several inflammatory effects. In this study, we investigated the edema and hyperalgesia induced in rats by Batroxase, a P-I metalloproteinase from Bothrops atrox venom, along with possible inflammatory mediators involved in these responses. Batroxase or sterile saline was injected into rat paws and the edema and hyperalgesic effects were evaluated for 6h by using a plethysmometer and a Von Frey system, respectively. Batroxase induced significant edematogenic and hyperalgesic peak responses in the first hours after administration. The inflammatory mediators involved in these responses were assayed by pretreatment of animals with synthesis inhibitors or receptor antagonists. Peak responses were significantly reduced by administration of the glucocorticoid dexamethasone, the H1 receptor antagonist diphenhydramine and the FLAP inhibitor MK-886. Rat paws injected with compound 48/80, a mast cell degranulating agent, followed by Batroxase injection resulted in significant reduction of the edema and hyperalgesia. However, Batroxase itself induced minor degranulation of RBL-2H3 mast cells in vitro. Additionally, the inflammatory responses did not seem to be related to prostaglandins, bradykinin or nitric oxide. Our results indicate a major involvement of histamine and leukotrienes in the edema and hyperalgesia induced by Batroxase, which could be related, at least in part, to mast cell degranulation.

Inhibition of the hemorrhagic and proteolytic activities of Lansberg's hognose pit viper (Porthidium lansbergii hutmanni) venom by opossum (Didelphis marsupialis) serum: isolation of Didelphis marsupialis 0.15Dm fraction on DEAE-cellulose chromatography

Earlier studies have revealed the ability of sera from several mammals to neutralize the toxic effects of snake venom. The Venezuelan opossum (Didelphis marsupialis) is one that has been found to inhibit hemorrhagic and proteolytic activities of venoms from many species of snakes. In this article it is shown that the opossum sera and its 0.15DM fraction were able to completely neutralize both hemorrhagic and hydrolysis (proteolysis) of casein effects induced by venom of the Lansberg's hognose pit viper (Porthidium lansbergii hutmanni). We have used DEAE-cellulose ion exchange chromatography to collect protein fractions from D. marsupialis sera which were able to defend mice from the lethal effects of P.l. hutmanni venom. The fractions separated were homogeneous by conventional electrophoresis using SDS-PAGE. The protein bands obtained contained molecular weights of approximately 6 to 220 kDa. These results revealed the presence of proteases inhibitors in the opossum sera fractions and the inhibition of venom activity by opossum sera suggesting a reciprocal adaptation at the molecular level.

Role of cyclooxygenases in oedema-forming activity of bothropic venoms

The venoms of Bothrops asper (BaV) and Bothrops jararaca (BjV), two of the most medically important poisonous snakes of Latin America, cause pronounced oedema in the victims through poorly understood mechanisms. In the present study, we examined the possible role of cyclooxygenases (COX) in the genesis of mouse paw oedema caused by BaV and BjV injections. BaV at 2.5 microg/paw and BjV at 0.75 microg/paw induced significant oedema that persisted for up to 6h following subplantar injection. Treatment with indomethacin (2 mg/kg), rofecoxib, (10 mg/kg), or dexamethasone (2 mg/kg) significantly reduced the BaV- and BjV-induced oedema formation. Treatment with SC-560 (30 mg/kg) significantly reduced the oedema formation induced by BjV but had no effect on that induced by BaV. Both venoms induced significant increases in the levels of prostaglandin E(2) (PGE(2)) and the expression of COX-1 and COX-2 in paw tissue. The peak of oedema formation and PGE(2) release correlated with marked expression of COX-2 in the paw tissue. These results demonstrate that injection of BaV and BjV results in a rapid increase in oedema formation that is, at least partially, mediated by arachidonic acid metabolites formed by COX-2. In the case of BjV, COX-1-derived prostanoids also appear to contribute significantly to the inflammatory changes.

Action of anti-bothropic factor isolated from Didelphis marsupialis on renal effects of Bothrops erythromelas venom

Acute renal failure is the most common complication in the lethal cases caused by snakebites in Brazil. Among the Brazilian venom snakes, Bothrops erythromelas is responsible for the majority of accidents in Northeastern Brazil. Didelphis marsupialis serum could inhibit myonecrotic, hemorrhagic, edematogenic hyperalgesic and lethal effects of envenomation determined by ophidian bites. In the present study, we evaluated the action of the anti-bothropic factor isolated from D. marsupialis on the renal effects promoted by B. erythromelas venom without systemic interference. Isolated kidneys from Wistar rats were perfused with Krebs-Henseleit solution containing 6% bovine serum albumin. We analyzed renal perfusion pressure (PP), renal vascular resistance (RVR), glomerular filtration rate (GFR), urinary flow (UF), and the percentages of sodium and potassium tubular transport (%TNa+, %TK+). The B. erythromelas venom (10 microg mL(-1)) decreased the PP (ct = 108.71+/-5.09 mmHg; BE = 65.21+/-5.6 mmHg*) and RVR (ct = 5.76+/-0.65 mmHg mL(-1) g(-1) min(-1); BE = 3.10+/-0.45 mmHg mL(-1) g(-1) min(-1)*). On the other hand, the GFR decreased at 60 min (ct60 = 0.76+/-0.07 mL g(-1) min(-1); BE60 = 0.42+/-0.12 mL g(-1) min(-1)*) and increased at 120 min (ct120 = 0.72+/-0.01 mL g(-1) min(-1); BE120 = 1.24+/-0.26 mL g(-1) min(-1)*). The UF increased significantly when compared with the control group (ct = 0.14+/-0.01 mL g(-1) min(-1); BE = 0.47+/-0.08 mL g(-1) min(-1)*). The venom reduced the %TNa(+) (ct90 = 79.18+/-0.88%; BE90 = 58.35+/-4.86%*) and %TK+ (ct90 = 67.20+/-4.04%; BE90 = 57.32+/-5.26%*) The anti-bothropic factor from D. marsupialis (10 microg mL(-1)) incubated with B. erythromelas venom (10 microg mL(-1)) blocked the effects on PP, RVR, %TNa+, and %TK+, but was not able to reverse the effects in UF and GFR promoted by venom alone. However, the highest concentration of D. marsupialis serum (30 microg mL(-1)) reversed all the renal effects induced by the venom. In conclusion, B. erythromelas venom altered all the renal functional parameters evaluated and the anti-bothropic factor from D. marsupialis was able to inhibit the effects induced by the venom in isolated kidney.

Natural inhibitors of snake venom hemorrhagic metalloproteinases

Metalloproteinases play an important role in the poisoning process by snake venoms. They evoke systemic injury, by degrading or activating host blood factors, and local damage by acting on endothelial cell surface proteins. Plasma and/or muscle of venomous and non-venomous snakes as well as of some special mammals possess metalloproteinase inhibitors that behave as soluble acceptors available for a rapid inhibition of the deleterious action of these enzymes. The purpose of this review is to describe the state of the art on natural immunity against snake venom metalloproteinases and to overview this field by discussing the available structural and biological properties of the inhibitors protein/gene families.

The C-terminus of murine S100A9 inhibits hyperalgesia and edema induced by jararhagin

The effect of a synthetic peptide (H92-G110) identical to the C-terminus of murine S100A9 (mS100A9p) was investigated on hyperalgesia and edema induced by either jararhagin or papain in the rat paw. mS100A9p not only reverted hyperalgesia and edema induced by jararhagin, but also the highest concentration induced antinociception. Hemorrhage induced by jararhagin and its hydrolytic activity were inhibited by mS100A9p. These data suggest that mS100A9p might block jararhagin-induced hyperalgesia and edema by inhibiting jararhagin catalytic activity, since papain-induced hyperalgesia and edema were not inhibited by mS100A9p.

PO41, a snake venom metalloproteinase inhibitor isolated from Philander opossum serum

PO41 was isolated from Philander opossum serum by DEAE-Sephacel, Phenyl Superose and Superdex 200 chromatographies and showed a molecular mass of 41,330 Da by MALDI-TOF MS. Molecular masses of 81.5 and 84.5 kDa were obtained by size exclusion chromatography and dynamic laser light scattering, respectively, suggesting that PO41 is dimeric. Its isoelectric point was estimated to be lower than 3.5. PO41 presented similar amino terminal sequence to those of DM40 and DM43, two antihaemorrhagins previously isolated from Didelphis marsupialis serum and was recognized by polyclonal antibodies raised against D. marsupialis antibothropic fraction. To study the inhibitory properties of this protein, the metalloproteinases bothrolysin and jararhagin were isolated from Bothrops jararaca venom by chromatographies on Superdex 200 and Phenyl Superose. Jararhagin was further submitted to a Mono Q column. The proteolytic and haemorrhagic effects of these haemorrhagins were neutralized by PO41. Both snake venom metalloproteinases formed stable complexes with PO41. The stoichiometry of the complex PO41-jararhagin was one inhibitor subunit to one molecule of the enzyme. These results show that PO41 has physicochemical, structural, immunoreactive and biological properties similar to other metalloproteinase inhibitors belonging to the supergene family of immunoglobulins.

Pharmacological characterization of mouse hind paw oedema induced by Bothrops insularis (jararaca ilhoa) snake venom

Bothrops snake venoms produce marked local effects, including oedema, haemorrhage and necrosis. The ability of Bothrops insularis venom to induce oedema in mice was investigated. Venom was injected into hind paws and the change in volume over time was measured by plethysmometry. B. insularis venom (0.01-2.5 microg/paw) induced paw oedema which, at high doses (>/=0.5 microg/paw), was accompanied by haemorrhage. The peak oedematogenic response occurred 3 h after venom injection with all doses and decreased gradually thereafter, but was still elevated with high doses after 24 h. Pretreating the mice with cyproheptadine (histamine H(1) and serotonin 5-HT(2) receptor antagonist), mepyramine (histamine H(1) receptor antagonist), L-NAME (inhibitor of nitric oxide synthase), indomethacin and rofecoxib (inhibitors of cyclooxygenases), and dexamethasone (indirect inhibitor of PLA(2)) significantly attenuated venom-induced oedema, whereas methysergide, a serotonin 5-HT(1)/5-HT(2) receptor antagonist, had no effect. The administration of antivenom 30 min before or immediately after venom injection also significantly inhibited venom-induced oedema. These results show that B. insularis venom causes oedema in the mouse hind paw and that this response is mediated by histamine, nitric oxide, and arachidonic acid metabolites formed by cyclooxygenases 1 and 2. The neutralization by commercial antivenom indicates that the venom components responsible for oedema are recognized by the antivenom and share immunological identity with their counterparts in the venoms of mainland Bothrops species.

Bothrops lanceolatus (Fer de lance) venom stimulates leukocyte migration into the peritoneal cavity of mice

The ability of Bothrops lanceolatus venom to induce neutrophil migration into the peritoneal cavity of mice was investigated. Intraperitoneal injection of venom caused dose- and time-dependent neutrophil migration, which peaked with 750 ng of venom/cavity 4h after venom injection. The neutrophil migration was significantly reduced by pretreatment with dexamethasone (0.5 mg/kg, s.c.), an indirect inhibitor of phospholipase A(2) (PLA(2)), and AA861 (0.01 mg/kg, s.c.), a 5-lipoxygenase inhibitor, but in contrast, was not modified by pretreatment with indomethacin (2 mg/kg, s.c.), an inhibitor of the cyclooxygenase pathway, meloxicam (5 mg/kg, s.c.), an inhibitor of the cyclooxygenase-2 pathway, or the PAF inhibitor WEB2086 (40 mg/kg, s.c.). Dexamethasone and AA861 also inhibited the neutrophil migration by 60% when administered immediately after venom injection, and the coadministration of these two drugs caused a 75% reduction in migration. BLV-induced neutrophil migration was not due to contamination by endotoxin since polymyxin B-treated venom retained its activity. Heating the venom (97 degrees C, 2 min) reduced the PLA(2) activity by 64% and this was accompanied by a corresponding reduction (68%) in neutrophil migration. These results suggest that arachidonate-derived lipoxygenase metabolites (possibly leukotriene B(4)) are involved in the chemotaxis observed. Macrophages may be an important source of these metabolites since the migratory response to venom was potentiated in mice pretreated with thioglycollate, but reduced when the peritoneal cavity was washed with sterile saline.

Structural and functional analyses of DM43, a snake venom metalloproteinase inhibitor from Didelphis marsupialis serum

DM43, an opossum serum protein inhibitor of snake venom metalloproteinases, has been completely sequenced, and its disulfide bond pattern has been experimentally determined. It shows homology to human alpha(1)B-glycoprotein, a plasma protein of unknown function and a member of the immunoglobulin supergene family. Size exclusion and dynamic laser light scattering data indicated that two monomers of DM43, each composed of three immunoglobulin-like domains, associated to form a homodimer in solution. Analysis of its glycan moiety showed the presence of N-acetylglucosamine, mannose, galactose, and sialic acid, most probably forming four biantennary N-linked chains. DM43 inhibited the fibrinogenolytic activities of bothrolysin and jararhagin and formed 1:1 stoichiometric stable complexes with both metalloproteinases. DM43 was ineffective against atrolysin C or A. No complex formation was detected between DM43 and jararhagin C, indicating the essential role of the metalloproteinase domain for interaction. Homology modeling based on the crystal structure of a killer cell inhibitory receptor suggested the existence of an I-type Ig fold, a hydrophobic dimerization surface and six surface loops potentially forming the metalloproteinase-binding surface on DM43.

Inhibitory properties of the anti-bothropic complex from Didelphis albiventris serum on toxic and pharmacological actions of metalloproteases and myotoxins from Bothrops asper venom

Anti-bothropic complex (ABC) was isolated from the serum of the South American opossum (Didelphis albiventris) by single-step affinity chromatography using a Sepharose-immobilized metalloprotease (BaP1) from Bothrops asper as the binding protein. Biochemical characterization of ABC showed the presence of two glycosylated subunits of 43 and 45 kDa, respectively, with an isoelectric point < 4. The two subunits were separated by ion-exchange HPLC. The N-terminal sequences of both subunits (LKAMDPTPXLWIETESP, where X is Arg-9 and Pro-9, respectively) showed a high degree of identity with other serum inhibitors isolated from different marsupials. Functional studies pointed out that ABC inhibits the hemorrhagic and proteolytic activities on fibrin, fibrinogen, and casein induced by the metalloproteases BaP1 and BaH4 isolated from B. asper venom. In addition to the anti-hemorrhagic and anti-proteolytic activities, ABC also showed anti-myotoxic, anti-lethal, and anti-edematogenic effects against myotoxic phospholipases A(2) isolated from the same venom. Moreover, it had inhibitory effects on the phospholipase A(2) activity of the crude venom as well as the isolated venom phospholipases A(2).

Pharmacological characterization of the rat paw edema induced by Bothrops lanceolatus (Fer de lance) venom

The inflammatory response induced by Bothrops lanceolatus venom (BLV) in the rat hind-paw was studied measuring paw edema. Non-heated BLV (75microg/paw) caused a marked paw edema accompanied by intense haemorrhage whereas heated venom (97 degrees C, 30s; 12.5-100microg/paw) produced a dose- and time-dependent non-haemorrhagic edema. The response with heated BLV was maximal within 15min disappearing over 24h. Heated venom was then routinely used at the dose of 75microg/paw. The prostacyclin analogue iloprost (0.1microg/paw) potentiated by 125% the venom-induced edema. The histamine H(1) receptor antagonist mepyramine (6mg/kg) or the serotonin/histamine receptor antagonist cyproheptadine (6mg/kg) partially inhibited BLV-induced edema whereas the combination of both compounds virtually abolished the edema. The lipoxygenase inhibitor BWA4C (10mg/kg), but not the cyclooxygenase inhibitor indomethacin (10mg/kg), significantly inhibited the edema (35% reduction; P<0.05). Dexamethasone (1mg/kg) also markedly (P<0.001) reduced venom-induced edema. The bradykinin B(2) receptor antagonist Hoe 140 (0.6mg/kg) reduced by 30% (P<0.05) the venom induced edema, whereas the angiotensin-converting enzyme inhibitor captopril (300microg/paw) potentiated by 42% (P<0.05) the edema. Bothrops lanceolatus antivenon (anti-BLV) reduced by 28% (P<0.05) the venom-induced edema while intravenous administration of antivenom failed to affect the edema. In conclusion, BLV-induced rat paw edema involves mast cell degranulation causing local release of histamine and serotonin, a phenomenon mediated mainly by kinins and lipoxygenase metabolites. Additionally, the use of a specific Bothrops lanceolatus antivenom, given subplantarily or intravenously, revealed to be little effective to prevent BLV-induced edema.

Inhibition of the hyperalgesic activity of Bothrops jararaca venom by an antibothropic fraction isolated from opossum (Didelphis marsupialis) serum

The antibothropic fraction (ABF) already isolated from Didelphis marsupialis serum, inhibits the haemorrhagic, oedematogenic, myonecrotic and lethal activities of Bothrops jararaca venom (Bjv). The aim of this work was to verify the capability of ABF to inhibit the hyperalgesic activity of Bjv. Intraplantar injection of Bjv induced hyperalgesia in a time- and dose-dependent manner and ABF administered in situ concomitantly with Bjv or i.v. 30 min before venom injection reduced the induced hyperalgesia. This same effect was observed when ABF was intravenously injected at 5 and 15 min after Bjv. Our results show that ABF inhibits also the hyperalgesia induced by Bjv.

Isolation and characterization of DM40 and DM43, two snake venom metalloproteinase inhibitors from Didelphis marsupialis serum

From Didelphis marsupialis serum, two antihemorrhagic proteins were isolated by DEAE-Sephacel, Phenyl-Sepharose and Superdex 200 and characterized. Their masses by mass spectrometry were 40318 AMU for DM40 and 42373 and 43010 AMU for DM43, indicating the presence of isoforms for the last. Molecular masses of 44.8 and 47.3 were obtained by SDS-PAGE, respectively for DM40 and DM43. Both inhibitors showed isoelectric points lower than 3.5 and glycosylation percentages varying from 20.5 to 29.0%, as estimated by chemical deglycosylation and amino acid analysis. N-terminal sequences of the first 17 residues of DM40 and DM43 were identical except for the exchange of R9 for P9. Both were homologous to oprin, a similar inhibitor from Didelphis virginiana serum. No evidence of complex formation between DM40 and DM43 was observed either by native PAGE or gel filtration chromatography. In addition to the antihemorrhagic activity, DM40 and DM43 inhibited the hydrolysis of casein, fibrinogen and fibronectin by Bothrops jararaca venom. DM43 also showed antilethal, antiedematogenic and antihyperalgesic activities. None of the inhibitors showed enzymatic activity on casein. Both proteins formed stable complexes with jararhagin and inhibited its hemorrhagic effect as well as the enzymatic activity of this toxin on fluorogenic substrate.

Bothrops lanceolatus (Fer de lance) venom induces oedema formation and increases vascular permeability in the mouse hind paw

The ability of snake venoms to increase vascular permeability and to induce oedema through the release of pharmacologically active substances is well known. We have studied the oedema and vascular permeability induced by Bothrops lanceolatus venom in male Swiss white mice. Paw oedema was induced by the subplantar injection of B. lanceolatus venom (125-1000 ng/paw) and was quantified as the increase in paw weight. Changes in vascular permeability were assessed by measuring the amount of Evans blue dye extravasation. The oedema and the increase in vascular permeability were maximal within 2 h and had resolved after 24 h. The administration of the vasodilator iloprost (20 ng/paw) immediately after B. lanceolatus venom potentiated the oedema and the increase in vascular permeability by approximately four-fold. Pretreating the mice with indomethacin, dexamethasone, NDGA or BW A4C inhibited the venom-induced oedema and the increase in vascular permeability. In contrast, histamine, serotonin and PAF-acether antagonists (mepyramine, cyproheptadine and WEB 2086, respectively) were ineffective. Histological examination showed that B. lanceolatus venom (250 ng and 500 ng/paw) caused thickening of the inner dermal layers which was accompanied by extensive intercellular spaces indicative of oedema. In addition, there was a marked infiltration of inflammatory cells, particularly neutrophils, into the underlying muscle layer. The latter, however, remained morphologically unaffected during the 3 h of observation. Venom doses larger than 500 ng/paw produced intense haemorrhage. These results indicate that B. lanceolatus venom induces oedema and increases vascular permeability in the mouse hind paw. The principal mediators of this inflammatory response are cyclooxygenase and lipoxygenase products.

Local haemorrhage induced by Bothrops jararaca venom: relationship to neurogenic inflammation

We investigated morphological alterations induced by s.c. injection of 2.5 microg of Bothrops jararaca venom in rats. Intense disorganisation of collagen fibres was observed 1 min after the venom injection, particularly at regions near vessels and nerves. Mast cells were degranulated, and erythrocytes were seen leaving venules throughout the endothelial junctions. At this time, damaged endothelial cells were not observed. In rats envenomed as above, but immediately after cardiorespiratory failure induced by deep ether anaesthesia, alterations in the connective tissue structures, as previously described, were not observed. The mediation of this haemorrhage was investigated by injecting the venom into the foot pad of mice and compared to the mediation of oedema. Local haemorrhage was significantly reduced in mice pre-treated with capsaicin or guanethidine or submitted to a surgical section of sciatic and saphenous nerves. In these animals, oedema was not affected. Groups treated with methysergide or morphine showed both haemorrhage and oedema significantly reduced. Indomethacin or dexamethasone pre-treatments significantly reduced the oedema, but not the haemorrhage. Moreover, in animals treated with promethazine or mepyramine, oedema and haemorrhage were not affected. These data suggest that local haemorrhage induced by Bothrops jararaca venom is partially controlled by serotonin and neurohumoral mediators. Furthermore, results indicate that haemorrhage and oedema are mediated by different pharmacological systems.

New methodology for the obtainment of antibothropic factors from the South American opossum (Didelphis marsupialis) and jararaca snake (Bothrops jararaca)

The antibothropic factor (ABF) from D. marsupialis was collected from perforated hollow plastic golf balls which were surgically implanted subcutaneously in anesthetized opossums, a technique originally described for the production of polyclonal antibodies. Two months after the implantation of the balls, approximately 15 ml of seromatous fluid from D. marsupialis (SFDm-50 mg total protein/ml) could be recovered monthly. Opossum serum as well as SFDm showed similar SDS-PAGE profiles and antihemorrhagic potencies against Bothrops jararaca snake venom (Bjv). The presence of ABF in SFDm was confirmed by immunoblotting, using rabbit polyclonal antibodies raised against ABF isolated from opossum serum. ABF isolated from SFDm or from serum by ion-exchange chromatography showed identical chromatographic and electrophoretic profiles. ABF fromboth sources displayed very similar antihemorrhagic and anticaseinolytic activities against Bjv. In the case of B. jararaca, polyethylene perforated tubes were inserted in the abdominal cavity and two months after implantation, approximately 4 ml of seromatous fluid from B. jararaca (SFBj-23 mg total protein/ml) were recovered. B.jararaca serum and SFBj showed the same native and SDS-PAGE band pattern. Both serum and SFBj inhibited Bjv hemorrhagic activity. We conclude that this new methodology is very suitable for continuously obtaining opossum ABF and SFBj, in large scale and in an easier way, avoiding animal suffering and eventual sacrifice.

Characterization of local tissue damage evoked by Bothrops jararaca venom in the rat connective tissue microcirculation: an intravital microscopic study

The aim of this study was to investigate the dynamic of the effects after topical application of Bothrops jararaca venom (BjV) on the microcirculation of the internal spermatic fascia of Wistar rats. The administration of 1 microg of BjV induced marked disturbances in capillaries and postcapillary venules, characterized by vasodilatation, fibrin clot formation, hemorrhagic lesions and alterations in the leukocyte-endothelial interactions. The installation and development of these effects occurred simultaneously. The application of higher dose of venom (10 microg) induced more intense effects, observed by the time-course of the beginning, evolution and intensity of the effects. The time-course of events suggests that an interaction of different effects occurs during the development of local symptoms following the exposure of tissues to BjV.

The antihemorrhagic factor of the Mexican ground squirrel, (Spermophilus mexicanus)

The Mexican ground squirrel (Spermophilus mexicanus) has a natural resistance to western diamondback rattlesnake venom (Crotalus atrox). The LD50 for the Mexican ground squirrel is 53 mg/kg body weight, which is 13 times higher than that of BALB/c mice. An antihemorrhagic factor from serum of the Mexican ground squirrel was isolated using Sephadex G-200 gel filtration, ion exchange A-50, G-75 gel filtration and HPLC DEAE 5PW ion exchange chromatography. The purified factor neutralized proteolytic and hemorrhagic activity of crude C. atrox venom. The results of this research suggest that the antihemorrhagic factor in the serum of the Mexican ground squirrel is not an antibody and neutralizes hemorrhagic activity of C. atrox venom.

Natural protease inhibitors to hemorrhagins in snake venoms and their potential use in medicine

Snake venoms are complex mixtures of many toxins and enzymes which effectively immobilize prey without a struggle and assist in digestion. Certain animals have a remarkable resistance to envenomation of snakes. Naturally occurring factors that neutralize snake venoms have been found in the sera of most snakes and a few warm-blooded animals. These antihemorrhagic and antineurotoxic factors have been purified from snake and mammalian sera. The antihemorrhagins are not immunoglobulins since they have different physical and chemical characteristics. The natural immunity to hemorrhagins is the result of tissue inhibitors of metalloproteinases (TIMP) found in animal sera of resistant animals. Most animals have matrix metalloproteinases (MMP) and TIMP that are implicated in a wide variety of normal physiological processes and pathological conditions. MMP in animals have many biological functions in embryogenesis, morphogenesis and tissue remodeling. MMP activities are precisely regulated by endogenous TIMP. Disruption of the balance between MMP and TIMP causes various diseases such as arthritis, periodontal diseases, diabetes, ophthalmologic conditions, neoplasia, metabolic bone disease, atherosclerosis and orthopedic conditions. Resistant animals that have a high titer of TIMP would have a survival advantage when bitten by poisonous snakes. Snake venoms are abundant and stable sources of MMP which are medically important. The venom MMP which cause unregulated destruction of tissue have sequences which have some degree of homology with mammalian MMP which control normal biological processes. Resistant animals are important sources of TIMP which can be used to study metalloproteinase related diseases. For these reasons the MMP in snakes and TIMP in resistant animal are excellent candidates for developing new drug therapies.

Snake envenomation and protective natural endogenous proteins: a mini review of the recent developments (1991-1997)

The properties of several factors--antihaemorrhagic, antineurotoxic, antimyotoxic--isolated from the blood serum or plasma of different animals are described with more emphasis placed on the structural differences and similarities among the factors of the snake (Trimeresurus flavoviridis) and mammals (Didelphis marsupials and Herpestes edwardsii). Classification of antihaemorrhagic factors of snake and mammals according to structural homologies, and their effectiveness in neutralizing venom haemorrhagic activities in comparison with that of commercial antivenoms are also reviewed. The antineurotoxic factors isolated so far from the sera of viperid (Vipera palestinae, Daboia r. siamensis), crotalid (Crotalus d. terrificus, T. flavoviridis, Agkistrodon b. siniticus) and elapid (Naja naja atra) snakes, as reviewed, are inhibitors of phospholipase A2, and the amino acid sequences, particularly of those inhibitors from the sera of crotalid snakes, do not share significant sequence homology even within the same family Crotalidae. The amino acid sequences of antineurotoxic factors of the snake (Crotalus d. terrificus) also are not homologous to those of the antihaemorrhagic factors from the blood of the snake (T. flavoviridis) or mammals (Didelphis virginiana, Herpestes edwardsii). The mechanism of action of antihaemorrhagic and antineurotoxic factors is briefly discussed as well as the possibility that crotalids and viperids might possess both of those endogenous neutralizing factors in their blood. Some recent findings on the antimyotoxic factors from the snake serum or plasma with inhibition properties against PLA2 activity and myotoxicity of venoms or toxins are also shortly reviewed.

Pharmacological aspects of mouse hind-paw oedema induced by Lachesis muta rhombeata venom

Pharmacological aspects of mouse hind-paw oedema induced by subplantar injections of Lachesis muta rhombeata (LMR) venom were investigated. The oedema induced by subplantar injections of 10 to 50 ng/g of LMR venom is dose dependent, with onset, peak and duration at 30, 60 and 180 min, respectively. Subplantar injection of 30 ng/g of Bothrops jararaca (BJ) venom induced oedema that has the same intensity as 30 ng/g of LMR venom but lasts for more than 4 h suggesting different time course. Systemic effects or haemorrhage were not observed with doses less than 50 ng/g. Oedema is not due to the presence of oedematogenic amines since dialysis did not change the oedema induced by 30 ng/g of LMR venom. Part of the oedema induced by LMR venom is due to a thermolabile fraction since pre-heating the venom at 100 degrees C for 15 min induced a significant reduction (56.19 +/- 6.8%) of the oedematogenic activity. The oedema induced by LMR venom is possibly induced by release of a pharmacological active substance at the site of injection. Histamine, arachidonate metabolites, nitric oxide and serotonin may play important roles in the oedematogenic effect of LMR venom since pre-treatment of mice with pyrilamine, indomethacin, dexamethasone, L-NAME and methysergide induced a significant reduction (49.86 +/- 10%; 51.06 +/- 5.9%; 77.66 +/- 3.6%; 73.30 +/- 6.1% and 93.77 +/- 2.8%, respectively) of the oedema formation. The present results demonstrate that the oedema induced by LMR and BJ venoms may be triggered and maintained by different pharmacological mechanisms. Since methysergide and L-NAME were the most active inhibitors of the oedema we can suggest that a link between serotonin release by the venom and a NO synthase activation may be an important step in the oedema formation induced by LMR venom.

Pharmacological profile of rat pleurisy induced by Bothrops jararaca venom

Bothrops jararaca venom (30 micrograms/site) triggered a marked inflammatory reaction in the pleural cavity that was long-lasting and reproducible. In the first 1 h after pleurisy induction, a significant decrease of total and differential cell count was observed in comparison with control values, despite the gradual enhancement of fluid leakage. A significant increase of cell migration was observed after 3 h of pleurisy induction, due to mononuclear and neutrophil cells that peaked 8 h later and this was followed by a gradual decrease, remaining elevated up to 24 h. In parallel with cell influx, a significant increase of fluid leakage that peaked between 1 and 8 h was observed, being completely abolished after 12 h following pleurisy induction. This inflammatory response was not associated in parallel with significant changes in circulating leucocyte cells and it was significantly inhibited by compound 48/80, cyproheptadine, pyrilamine, dexamethasone, indomethacin and phenidone. Preheating of the venom (100 degrees C) caused a significant decrease of both leakage of fluid and cell migration in the pleural cavity 8 h after pleurisy induction. Previous exposure to the venom (30 micrograms/site, 5 days before) produced a significant decrease of both cell migration and fluid leakage 4 h after triggering pleurisy with the same dose of the venom. Otherwise, prior daily treatment with the venom (10 micrograms/site, 4 days) resulted only in marked fluid leakage reduction 1 h after treating the animals with BJV (30 micrograms/site). These results show that the venom elicits pro-inflammatory effects in the rat pleural cavity which involve the participation of several mediators, including histamine, 5-hydroxytryptamine and products of arachidonic pathways.