Leukocyte response induced by Bothrops jararaca crude venom: in vivo and in vitro studies

Molecular Aspects Involved in the Mechanisms of Bothrops jararaca Venom-Induced Hyperalgesia: Participation of NK1 Receptor and Glial Cells

Accidents caused by Bothrops jararaca (Bj) snakes result in several local and systemic manifestations, with pain being a fundamental characteristic. The inflammatory process responsible for hyperalgesia induced by Bj venom (Bjv) has been studied; however, the specific roles played by the peripheral and central nervous systems in this phenomenon remain unclear. To clarify this, we induced hyperalgesia in rats using Bjv and collected tissues from dorsal root ganglia (DRGs) and spinal cord (SC) at 2 and 4 h post-induction. Samples were labeled for Iba-1 (macrophage and microglia), GFAP (satellite cells and astrocytes), EGR1 (neurons), and NK1 receptors. Additionally, we investigated the impact of minocycline, an inhibitor of microglia, and GR82334 antagonist on Bjv-induced hyperalgesia. Our findings reveal an increase in Iba1 in DRG at 2 h and EGR1 at 4 h. In the SC, markers for microglia, astrocytes, neurons, and NK1 receptors exhibited increased expression after 2 h, with EGR1 continuing to rise at 4 h. Minocycline and GR82334 inhibited venom-induced hyperalgesia, highlighting the crucial roles of microglia and NK1 receptors in this phenomenon. Our results suggest that the hyperalgesic effects of Bjv involve the participation of microglial and astrocytic cells, in addition to the activation of NK1 receptors.

Exploring the Profile of Cell Populations and Soluble Immunological Mediators in Bothrops atrox Envenomations

Bothrops atrox envenomations are common in the Brazilian Amazon. The venom of B. atrox is highly inflammatory, which results in severe local complications, including the formation of blisters. Moreover, there is little information on the immune mechanisms associated with this condition. Thus, a longitudinal study was carried out to characterize the profile of the cell populations and soluble immunological mediators in the peripheral blood and blisters in B. atrox patients s according to their clinical manifestations (mild and severe). A similar response in both B. atrox patient groups (MILD and SEV) was observed, with an increase in inflammatory monocytes, NKT, and T and B cells, as well as CCL2, CCL5, CXCL9, CXCL10, IL-1β and IL-10, when compared with the group of healthy blood donors. After the administration of antivenom, the participation of patrolling monocytes and IL-10 in the MILD group was observed. In the SEV group, the participation of B cells was observed, with high levels of CCL2 and IL-6. In the blister exudate, a hyperinflammatory profile was observed. In conclusion, we revealed the involvement of cell populations and soluble mediators in the immune response to B. atrox envenomation at the local and peripheral level, which is related to the onset and extent of the inflammation/clinical manifestation.

Bothrops jararaca Snake Venom Inflammation Induced in Human Whole Blood: Role of the Complement System

The clinical manifestations of envenomation by Bothrops species are complex and characterized by prominent local effects that can progress to tissue loss, physical disability, or amputation. Systemic signs can also occur, such as hemorrhage, coagulopathy, shock, and acute kidney failure. The rapid development of local clinical manifestations is accompanied by the presence of mediators of the inflammatory process originating from tissues damaged by the bothropic venom. Considering the important role that the complement system plays in the inflammatory response, in this study, we analyzed the action of Bothrops jararaca snake venom on the complement system and cell surface receptors involved in innate immunity using an ex vivo human whole blood model. B. jararaca venom was able to induce activation of the complement system in the human whole blood model and promoted a significant increase in the production of anaphylatoxins C3a/C3a-desArg, C4a/C4a-desArg, C5a/C5a-desArg and sTCC. In leukocytes, the venom of B. jararaca reduced the expression of CD11b, CD14 and C5aR1. Inhibition of the C3 component by Cp40, an inhibitor of C3, resulted in a reduction of C3a/C3a-desArg, C5a/C5a-desArg and sTCC to basal levels in samples stimulated with the venom. Exposure to B. jararaca venom induced the production of inflammatory cytokines and chemokines such as TNF-α, IL-8/CXCL8, MCP-1/CCL2 and MIG/CXCL9 in the human whole blood model. Treatment with Cp40 promoted a significant reduction in the production of TNF-α, IL-8/CXCL8 and MCP-1/CCL2. C5aR1 inhibition with PMX205 also promoted a reduction of TNF-α and IL-8/CXCL8 to basal levels in the samples stimulated with venom. In conclusion, the data presented here suggest that the activation of the complement system promoted by the venom of the snake B. jararaca in the human whole blood model significantly contributes to the inflammatory process. The control of several inflammatory parameters using Cp40, an inhibitor of the C3 component, and PMX205, a C5aR1 antagonist, indicates that complement inhibition may represent a potential therapeutic tool in B. jararaca envenoming.

Pain and Cellular Migration Induced by Bothrops jararaca Venom in Mice Selected for an Acute Inflammatory Response: Involvement of Mast Cells

Bothrops jararaca venom (BjV) can induce mast cell degranulation. In order to investigate the role of mast cells and the interference of the host genetic background in the inflammation induced by BjV, we have used mouse strains selected for maximal (AIRmax) or minimal (AIRmin) acute inflammatory response (AIR). Mice were pretreated with an inhibitor of mast cell degranulation, cromolyn (CROM), and injected in footpads or intraperitoneally (i.p.) with BjV. Pain was measured with von Frey hairs, cell migration in the peritoneum by flow cytometry, and reactive oxygen species (ROS) production by chemiluminescence assays. The nociceptive response to BjV was higher in AIRmax than AIRmin mice; however, this difference was abolished by pretreatment with CROM. BjV induced peritoneal neutrophil (CD11b+ GR-1+) infiltration and ROS secretion in AIRmax mice only, which were partially inhibited by CROM. Our findings evidence a role for mast cells in pain, neutrophil migration, and ROS production triggered by BjV in AIRmax mice that are more susceptible to the action of BjV.

Bitis arietans Snake Venom and Kn-Ba, a Snake Venom Serine Protease, Induce the Production of Inflammatory Mediators in THP-1 Macrophages

Bitis arietans is a snake of medical importance found throughout sub-Saharan Africa and in savannas and pastures of Morocco and western Arabia. The effects of its venom are characterized by local and systemic alterations, such as inflammation and cardiovascular and hemostatic disturbances, which can lead to victims' death or permanent disability. To better characterize the inflammatory process induced by this snake's venom, the participation of eicosanoids and PAF (platelet- activating factor) in this response were demonstrated in a previous study. In addition, edema and early increased vascular permeability followed by an accumulation of polymorphonuclear (PMN) cells in the peritoneal cavity were accompanied by the production of the eicosanoids LTB₄, LTC₄, TXB₂, and PGE₂, and local and systemic production of IL-6 and MCP-1. In this context, the present study focused on the identification of inflammatory mediators produced by human macrophages derived from THP-1 cells in response to Bitis arietans venom (BaV), and Kn-Ba, a serine protease purified from this venom. Here, we show that Kn-Ba, and even the less intensive BaV, induced the production of the cytokine TNF and the chemokines RANTES and IL-8. Only Kn-Ba was able to induce the production of IL-6, MCP-1, and IP-10, whereas PGE₂ was produced only in response to BaV. Finally, the release of IL-1β in culture supernatants suggests the activation of the inflammasomes by the venom of Bitis arietans and by Kn-Ba, which will be investigated in more detail in future studies.

Inflammatory mediators in the pronociceptive effects induced by Bothrops leucurus snake venom: The role of biogenic amines, nitric oxide, and eicosanoids

Bothrops leucurus is the major causative agent of venomous snakebites in Northeastern Brazil. Severe pain is the most frequent symptom in these envenomings, with an important inflammatory component. This work characterized the pronociceptive effects evoked by B. leucurus venom (BLV) in mice and the role of inflammatory mediators in these responses. The nociceptive behaviors were quantified by the modified formalin test. The mechanical hyperalgesia was assessed by the digital von Frey test. Pharmacological assays were performed with different antagonists and synthesis inhibitors to investigate the involvement of inflammatory mediators in both nociceptive events. BLV (1-15 μg/paw) injection in mice evoked intense and dose-dependent nociceptive behaviors that lasted for up to 1 h. BLV (10 μg/paw) also caused sustained mechanical hyperalgesia. Histamine and serotonin played a role in the nociception, but not in the BLV-induced mechanical hyperalgesia. Nitric oxide contributed to both responses, but only to the late stages of mechanical hyperalgesia. Eicosanoids were also present in both nociceptive responses. Prostanoid synthesis by COX-1 seemed to be more relevant for the nociception, whereas COX-2 had a more prominent role in the mechanical hyperalgesia. Leukotrienes were the most relevant mediators of BLV-induced mechanical hyperalgesia, hence inhibiting lipoxygenase pathway could be an efficient therapeutic strategy for pain management during envenoming. Our behavioral data demonstrates that BLV promotes nociceptive transmission mediated by biogenic amines, nitric oxide and eicosanoids, and nociceptor sensitization through nitric oxide and eicosanoids. Moreover, phospholipases A₂ (PLA₂), an important class of toxins present in bothropic venoms, appear to play an important role in the nociceptive and hypernociceptive response induced by BLV.

Bitis arietans Snake Venom Induces an Inflammatory Response Which Is Partially Dependent on Lipid Mediators

Bitis arietans is a snake of medical importance, as it is responsible for more accidents in humans and domestic animals than all other African snakes put together. The accidents are characterized by local and systemic alterations, such as inflammation, cardiovascular and hemostatic disturbances, which can lead victims to death or permanent disability. However, little is known about the envenomation mechanism, especially regarding the inflammatory response, which is related to severe clinical conditions triggered by the venom. Therefore, the aim of the present study was to evaluate the inflammatory response related to the B. arietans envenomation using a peritonitis mice model. By pharmacological interventions and use of mice genetically deficient of the 5-lipoxygenase enzyme (5-LO^-/-) or platelet-activating factor (PAF) receptor (PAFR^-/- the participation of eicosanoids and PAF in this response was also investigated. The obtained results demonstrated that the venom induces an in vivo inflammatory response, characterized by an early increased vascular permeability, followed by an accumulation of polymorphonuclear (PMN) cells in the peritoneal cavity, accompanied by the production of the eicosanoids LTB₄, LTC₄, TXB₂ and PGE₂, as well as the local and systemic production of IL-6 and MCP-1. These inflammatory events were attenuated by the pre-treatment with anti-inflammatory drugs that interfere in lipid mediators' functions. However, 5-LO^-/- mice did not show a reduction of inflammatory response induced by the venom, while PAFR^-/- mice showed a reduction in both the PMN leukocytes number and the local and systemic production of IL-6 and MCP-1. This study demonstrated that the Bitis arietans venom contains toxins that trigger an inflammatory process, which is partially dependent on lipid mediators, and may contribute to the envenomation pathology.

Inflammation Induced by Platelet-Activating Viperid Snake Venoms: Perspectives on Thromboinflammation

Envenomation by viperid snakes is characterized by systemic thrombotic syndrome and prominent local inflammation. To date, the mechanisms underlying inflammation and blood coagulation induced by Viperidae venoms have been viewed as distinct processes. However, studies on the mechanisms involved in these processes have revealed several factors and signaling molecules that simultaneously act in both the innate immune and hemostatic systems, suggesting an overlap between both systems during viper envenomation. Moreover, distinct classes of venom toxins involved in these effects have also been identified. However, the interplay between inflammation and hemostatic alterations, referred as to thromboinflammation, has never been addressed in the investigation of viper envenomation. Considering that platelets are important targets of viper snake venoms and are critical for the process of thromboinflammation, in this review, we summarize the inflammatory effects and mechanisms induced by viper snake venoms, particularly from the Bothrops genus, which strongly activate platelet functions and highlight selected venom components (metalloproteases and C-type lectins) that both stimulate platelet functions and exhibit pro-inflammatory activities, thus providing insights into the possible role(s) of thromboinflammation in viper envenomation.

Cytotoxic and inflammatory potential of a phospholipase A2 from Bothrops jararaca snake venom

Background

Snake venom phospholipases A₂ (PLA₂s) have been reported to induce myotoxic, neurotoxic, hemolytic, edematogenic, cytotoxic and proinflammatory effects. This work aimed at the isolation and functional characterization of a PLA₂ isolated from Bothrops jararaca venom, named BJ-PLA₂-I.

Methods and Results

For its purification, three consecutive chromatographic steps were used (Sephacryl S-200, Source 15Q and Mono Q 5/50 GL). BJ-PLA₂-I showed acidic characteristics, with pI~ 4.4 and molecular mass of 14.2 kDa. Sequencing resulted in 60 amino acid residues that showed high similarity to other Bothrops PLA₂s, including 100% identity with BJ-PLA₂, an Asp49 PLA₂ previously isolated from B. jararaca venom. Being an Asp49 PLA₂, BJ-PLA₂-I showed high catalytic activity, and also inhibitory effects on the ADP-induced platelet aggregation. Its inflammatory characterization showed that BJ-PLA₂-I was able to promote leukocyte migration in mice at different concentrations (5, 10 and 20 μg/mL) and also at different response periods (2, 4 and 24 h), mainly by stimulating neutrophil infiltration. Furthermore, increased levels of total proteins, IL-6, IL-1β and PGE₂ were observed in the inflammatory exudate induced by BJ-PLA₂-I, while nitric oxide, TNF-α, IL-10 and LTB₄ levels were not significantly altered. This toxin was also evaluated for its cytotoxic potential on normal (PBMC) and tumor cell lines (HL-60 and HepG2). Overall, BJ-PLA₂-I (2.5–160 μg/mL) promoted low cytotoxicity, with cell viabilities mostly varying between 70 and 80% and significant values obtained for HL-60 and PBMC only at the highest concentrations of the toxin evaluated.

Conclusions

BJ-PLA₂-I was characterized as an acidic Asp49 PLA₂ that induces acute local inflammation and low cytotoxicity. These results should contribute to elucidate the action mechanisms of snake venom PLA₂s.

Rutin (quercetin-3-rutinoside) modulates the hemostatic disturbances and redox imbalance induced by Bothrops jararaca snake venom in mice

Snakebites are a major Collective Health problem worldwide. In Brazil, Bothrops jararaca snake venom (BjV) evokes hemostatic disturbances, bleeding manifestations, and redox status imbalance. Specific antivenom therapy, although efficacious to revert most snakebite-induced manifestations, is incapable of treating secondary manifestations, such as oxidative/nitrosative stress. Searching for new complementary therapies that could attenuate physiological derangements triggered by envenomation, we elected to test quercetin-3-rutinoside (rutin) by its potential as both a potent antioxidant and a hemostasis modulatory compound. The activity of rutin was evaluated both on the biological activities of crude BjV in vitro, and in vivo by the ability of rutin (14.4 mg/kg b.w.) to modulate hematological, hemostatic and redox status markers altered by BjV injection (1.6 mg/kg b.w., s.c.) in mice. In vitro, rutin failed to inhibit BjV-induced platelet aggregation and biological activities of major BjV enzymes (metalloproteinases, phospholipases A2, serine proteases, and L-amino acid oxidases). On the other hand, rutin attenuated local hemorrhage, and the increase in reactive species, prevented the fall in RBC counts and fibrinogen levels, diminished tail bleeding and shortened prothrombin time (PT) evoked by envenomation. Furthermore, rutin reduced tissue factor (TF) activity and altered the protein expression of TF in liver, lungs, heart and skin. In conclusion, the disturbances in redox status and hemostatic system induced by B. jararaca envenomation were modulated by rutin, suggesting it has a great potential to be used as an ancillary therapeutic agent for snakebites.

Secreted Phospholipases A₂ from Animal Venoms in Pain and Analgesia

Animal venoms comprise a complex mixture of components that affect several biological systems. Based on the high selectivity for their molecular targets, these components are also a rich source of potential therapeutic agents. Among the main components of animal venoms are the secreted phospholipases A₂ (sPLA₂s). These PLA₂ belong to distinct PLA₂s groups. For example, snake venom sPLA₂s from Elapidae and Viperidae families, the most important families when considering envenomation, belong, respectively, to the IA and IIA/IIB groups, whereas bee venom PLA₂ belongs to group III of sPLA₂s. It is well known that PLA₂, due to its hydrolytic activity on phospholipids, takes part in many pathophysiological processes, including inflammation and pain. Therefore, secreted PLA₂s obtained from animal venoms have been widely used as tools to (a) modulate inflammation and pain, uncovering molecular targets that are implicated in the control of inflammatory (including painful) and neurodegenerative diseases; (b) shed light on the pathophysiology of inflammation and pain observed in human envenomation by poisonous animals; and, (c) characterize molecular mechanisms involved in inflammatory diseases. The present review summarizes the knowledge on the nociceptive and antinociceptive actions of sPLA₂s from animal venoms, particularly snake venoms.

Aqueous Leaf Extract of Jatropha mollissima (Pohl) Bail Decreases Local Effects Induced by Bothropic Venom

Snakebites are a serious worldwide public health problem. In Brazil, about 90% of accidents are attributed to snakes from the Bothrops genus. The specific treatment consists of antivenom serum therapy, which has some limitations such as inability to neutralize local effects, difficult access in some regions, risk of immunological reactions, and high cost. Thus, the search for alternative therapies to treat snakebites is relevant. Jatropha mollissima (Euphorbiaceae) is a medicinal plant popularly used in folk medicine as an antiophidic remedy. Therefore, this study aims to evaluate the effect of the aqueous leaf extract from J. mollissima on local effects induced by Bothrops venoms. High Performance Liquid Chromatography with Diode Array Detection analysis and Mass Spectrometry analysis of aqueous leaf extract confirmed the presence of the flavonoids isoschaftoside, schaftoside, isoorientin, orientin, vitexin, and isovitexin. This extract, at 50–200 mg/kg doses administered by intraperitoneal route, showed significant inhibitory potential against local effects induced by Bothrops erythromelas and Bothrops jararaca snake venoms. Local skin hemorrhage, local edema, leukocyte migration, and myotoxicity were significantly inhibited by the extract. These results demonstrate that J. mollissima extract possesses inhibitory potential, especially against bothropic venoms, suggesting its potential as an adjuvant in treatment of snakebites.

Pharmacological activity of Costus spicatus in experimental Bothrops atrox envenomation

CONTEXT

Medicinal plants encompass a rich source of active compounds that can neutralize snake venoms or toxins. Costus spicatus (Jacq.) Sw. (Costaceae) is used by the Amazonian population to treat inflammation, pain and other pathological manifestations.

OBJECTIVE

To evaluate the influence of C. spicatus aqueous extract on edema, peritonitis, nociception, coagulation, haemorrhage and indirect haemolytic activity induced by Bothrops atrox venom (BAV).

MATERIALS AND METHODS

Dried and pulverized leaves were extracted with distilled water. Envenoming was induced by administration of B. atrox snake venom in Swiss Webster mice. The experimental groups consisted of BAV (at the minimum dose to induce measurable biological responses) and C. spicatus extract (CSE, 1.25, 2.5, 5.0, 7.5 and 10 mg/kg/25 μl phosphate-buffered saline) administered individually and in combination (BAVCSE). PBS was used as a control. In vitro assays were also conducted in order to evaluate phospholipase A2 coagulant activities (indirect haemolytic method).

RESULTS

CSE significantly reduced the venom-induced edema and nociception at all concentrations tested and inhibited migration of inflammatory cells at the three least concentrations (5.0, 7.5 and 10 mg/kg/25 μl PBS). CSE was not effective in inhibiting coagulant, haemorrhagic and indirect haemolytic activities of the venom.

DISCUSSION AND CONCLUSION

The data suggest that CSE could exhibit a central mechanism for pain inhibition, and may also inhibit prostaglandin synthesis. These findings corroborate the traditional administration of C. spicatus decoction to treat inflammatory disorders, including those caused by B. atrox envenomation.

Biological characterization of compounds from Rhinella schneideri poison that act on the complement system

Background

The skin secretions of toads of the family Bufonidae contain biogenic amines, alkaloids, steroids (bufotoxins), bufodienolides (bufogenin), peptides and proteins. The poison of Rhinella schneideri, formerly classified as Bufo paracnemis, presents components that act on different biological systems, including the complement system. The aim of this study was to isolate and examine the activity of Rhinella schneideri poison (RsP) components on the complement system.

Methods

The components active on the complement system were purified in three chromatographic steps, using a combination of cation-exchange, anion-exchange and gel filtration chromatography. The resulting fractions were analyzed by SDS-PAGE and screened for their activity in the hemolytic assay of the classical/lectin complement pathways. Fractions active on the complement system were also assessed for their ability to generate C3 fragments evaluated by two dimensional immunoelectrophoresis assay, C3a and C5a by neutrophil chemotaxis assay and SC5b-9 complex by ELISA assay.

Results

The fractionation protocol was able to isolate the component S5 from the RsP, as demonstrated by SDS-PAGE and the RP-FPLC profile. S5 is a protein of about 6000 Da, while S2 presents components of higher molecular mass (40,000 to 50,000 Da). Fractions S2 and S5 attenuated the hemolytic activity of the classical/lectin pathways after preincubation with normal human serum. Both components stimulated complement-dependent neutrophil chemotaxis and the production of C3 fragments, as shown by two-dimensional immunoelectrophoresis. S2 showed a higher capacity to generate the SC5b-9 complex than the other fractions. This action was observed after the exposure of normal human serum to the fractions.

Conclusions

This is the first study to examine the activity of RsP components on the complement system. Fractions S2 and S5 reduced the complement hemolytic activity, stimulated complement-dependent neutrophil chemotaxis and stimulated the production of C3 fragments, indicating that they were able to activate the complement cascade. Furthermore, fraction S2 was also able to generate the SC5b-9 complex. These components may be useful tools for studying dysfunction of the complement cascade.

Animal venoms/toxins and the complement system

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

Characterization of inflammatory response induced by Potamotrygon motoro stingray venom in mice

Freshwater stingray accidents cause intense pain followed by edema, erythema, and necrosis formation. Treatment for stingray envenomation is based on administration of analgesic, antipyretic, and anti-inflammatory drugs. This report evaluated the local inflammatory reaction—including edema formation, leukocyte recruitment, release of inflammatory mediators, and histopathological changes—after the intraplantar injection of Potamotrygon motoro stingray venom in mice. Edema was observed as soon as 15 min after venom injection, peaking at 30 min, and lasted up to 48 h. In addition, P. motoro venom increased neutrophil counts in the site of injection, at all time periods and venom doses analyzed. Increased eosinophil and lymphocyte counts were detected mainly at 24 h. Moreover, monocytes/macrophages were observed in large amounts at 24 and 48 h. Microscopically, the venom induced leukocyte migration to the injured tissue, edema, mast cell degranulation, angiogenesis, and epidermal damage. Inflammatory mediator release (IL-6, MCP-1 and KC) was detected as soon as 1 h after venom injection, and it increased significantly at 4 h. At 24 h, the venom induced only the production of MCP-1. These results show that this stingray venom evokes a complex inflammatory reaction, with rapid and persistent edema formation, leukocyte recruitment, and release of cytokines and chemokines.

Effect of Bothrops bilineata snake venom on neutrophil function

The aim of the study was to evaluate the in vitro effects of Bothrops bilineata crude venom (BbV) on isolated human neutrophil function. We proved that BbV isn't toxic towards human neutrophils. During an incubation of human neutrophils with BbV hydrogen peroxide was produced. Moreover, BbV was able to stimulate neutrophil release of proinflammatory mediators such as IL-8 and IL-6 as well as PGE2 and NETs liberation. There is no data in the literature showing the effect of BbV on the production of IL-6 and IL-8 or NETs liberation by isolated human neutrophils. Taken together our results testify that BbV triggers relevant proinflammatory events in human neutrophils.

Effects of phospholipase A2 and metalloprotease fractions of Russell's viper venom on cytokines and renal hemodynamics in dogs

Several enzymes in Russell's viper (Daboia siamensis) venom are involved in the venom effects and renal injury. The effects of fractional components of Russell's viper venom, phospholipase A(2) and metalloprotease fractions, were examined in two groups of four experimental dogs each. Animals received an intravenous injection of 140 μg/kg of each venom fraction. The inflammatory effects and renal hemodynamic changes were assessed. Plasma concentrations of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and PGE2 were elevated by both phospholipase A(2) (PLA(2)) and metalloprotease (MP) fractions. The plasma level of nitric oxide was increased after PLA(2) fraction injection but not with MP fraction injection. Leukocytosis with increase in lymphocytes, monocytes and granulocytes was observed after both PLA(2) and MP injections. Results from this study suggested that both PLA(2) and MP were inflammatory. Increased red blood cell count, hematocrit and hemoglobin concentration were observed in animals injected with PLA(2) fraction, but not with MP fraction. Hemodynamically, PLA(2) fraction induced marked decrease in mean arterial pressure with decreased renal vascular resistance initially followed later by increased renal vascular resistance. MP fraction caused less decrease of mean arterial pressure but increased renal vascular resistance throughout the experiment. Both enzymes decreased renal blood flow, glomerular filtration rate and urine flow. The findings indicate vasodilating effect of PLA(2) fraction and vasoconstricting effect and decreased cardiac function of MP fraction.

Local inflammatory events induced by Bothrops atrox snake venom and the release of distinct classes of inflammatory mediators

Bothrops atrox is responsible for most accidents involving snakes in the Brazilian Amazon and its venom induces serious systemic and local effects. The local effects are not neutralized effectively by commercial antivenoms, resulting in serious sequelae in individuals bitten by this species. This study investigates the local inflammatory events induced in mice by B. atrox venom (BaV), such as vascular permeability, leukocyte influx and the release of important inflammatory mediators such as cytokines, eicosanoids and the chemokine CCL-2, at the injection site. The effect of BaV on cyclooxygenase (COX-1 and COX-2) expression was also investigated. The results showed that intraperitoneal (i.p.) injection of BaV promoted a rapid and significant increase in vascular permeability, which reached a peak 1 h after venom administration. Furthermore, BaV caused leukocyte infiltration into the peritoneal cavity between 1 and 8 h after i.p. injection, with mononuclear leukocytes (MNs) predominating in the first 4 h, and polymorphonuclear leukocytes (PMNs) in the last 4 h. Increased protein expression of COX-2, but not of COX-1, was detected in leukocytes recruited in the first and fourth hours after injection of BaV. The venom caused the release of eicosanoids PGD₂, PGE₂, TXA₂ and LTB₄, cytokines TNF-α, IL-6, IL-10 and IL-12p70, but not IFN-γ, and chemokine CCL-2 at different times. The results show that BaV is able to induce an early increase in vascular permeability and a leukocyte influx to the injection site consisting mainly of MNs initially and PMNs during the later stages. These phenomena are associated with the production of cytokines, the chemokine CCL-2 and eicosanoids derived from COX-1 and COX-2.

Effect of purified Russell's viper venom-factor X activator (RVV-X) on renal hemodynamics, renal functions, and coagulopathy in rats

Acute renal failure (ARF) is the most frequent and a serious complication in victims of Russell's viper snakebites. Russell's viper venom-factor X activator (RVV-X) has been identified as a main procoagulant enzyme involving coagulopathy, which might be responsible for changes in renal hemodynamics and renal functions. Here, we purified RVV-X from crude Russell's viper venom to study renal hemodynamics, renal functions, intravascular clot, and histopathological changes in Sprague-Dawley rats. Changes in renal hemodynamics and renal functions were evaluated by measuring the mean arterial pressure, glomerular filtration rate (GFR), effective renal plasma flow (ERPF), effective renal blood flow (ERBF), renal vascular resistance (RVR), and fractional excretion of electrolytes. After 10 min, rats receiving both crude venom and purified RVV-X decreased GFR, ERPF, and ERBF and increased RVR. These changes correlated to renal lesions. Along with the determination of intravascular clot, rats injected with purified RVV-X increased the average D-dimer level and reached a peak at 10 min, declined temporarily, and then reached another peak at 30 min. The temporal association between clots and renal dysfunction was observed in rats within 10 min after the injection of purified RVV-X. These findings suggested RVV-X as a major cause of renal failure through intravascular clotting in the renal microcirculation.

Dietary free oleic and linoleic acid enhances neutrophil function and modulates the inflammatory response in rats

The high ingestion of oleic (OLA) and linoleic (LNA) acids by Western populations, the presence of inflammatory diseases in these populations, and the importance of neutrophils in the inflammatory process led us to investigate the effects of oral ingestion of unesterified OLA and LNA on rat neutrophil function. Pure OLA and LNA were administered by gavage over 10 days. The doses used (0.11, 0.22 and 0.44 g/kg of body weight) were based on the Western consumption of OLA and LNA. Neither fatty acid affected food, calorie or water intake. The fatty acids were not toxic to neutrophils as evaluated by cytometry using propidium iodide (membrane integrity and DNA fragmentation). Neutrophil migration in response to intraperitoneal injection of glycogen and in the air pouch assay, was elevated after administration of either OLA or LNA. This effect was associated with enhancement of rolling and increased release of the chemokine CINC-2alphabeta. Both fatty acids elevated L-selectin expression, whereas no effect on beta(2)-integrin expression was observed, as evaluated by flow cytometry. LNA increased the production of proinflammatory cytokines (IL-1beta and CINC-2alphabeta) by neutrophils after 4 h in culture and both fatty acids decreased the release of the same cytokines after 18 h. In conclusion, OLA and LNA modulate several functions of neutrophils and can influence the inflammatory process.

Epidemiological, clinical characteristics and outcome of severe scorpion envenomation in South Tunisia: multivariate analysis of 951 cases

The aim of this retrospective descriptive study was to describe both epidemiologically and clinically manifestations following severe scorpion envenomation and to define simple predictive factors which can be used in routine practice in general Intensive Care Units (ICU) as an indicator of poor prognosis. Cases were collected from hospital patients' files during 13-year (1990-2002) period in the medical Intensive Care Unit of a university hospital (Sfax - Tunisia). The diagnosis of scorpion envenomation was based on a history of scorpion sting. Nine hundred fifty-one patients, who were admitted for a scorpion sting, were analyzed. There were 769 patients (80.8%) in the grade III group (with cardiogenic shock and/or pulmonary edema or severe neurological manifestation (coma and/or convulsion)) and 182 patients (19.2%) in the grade II group (with systemic manifestations). Scorpion envenomation is more frequent in summer; indeed 82.3% of our patients were admitted between June and September. The mean age (+/-SD) was 14.7 +/- 17.4 years, ranging from 0.5 to 90 years. In this study 739 patients (77.8%) had neuromuscular signs, 700 patients (73.6%) had gastrointestinal signs and 585 patients (61.5%) had a pulmonary edema, while 195 patients (20.5%) had a cardiogenic shock. The mean blood sugar on admission was at 11.32 +/- 5.66 mmol/l, a high blood sugar level (>11 mmol/l) was observed in 39% of cases. The mean blood urea was at 7.1 +/- 3.2 mmol/l, it was above 10 mmol/l in 10.7% of cases. The mean of leucocytes was at 17 418 +/- 7833 cells/mm(3), it was above 11 000/mm(3) in 80% of cases. In the end of the stay in ICU, evolution was marked by the improvement of 879 patients (92.5%) while 72 patients (7.5%) died. A multivariate analysis found the following factors to be correlated with a poor outcome: age less than 5 years (OR = 2.27), fever >38.5 degrees C (OR = 2.79), coma with Glasgow coma score < or =8/15 (OR = 9.87), pulmonary edema (OR = 8.46), leucocytes >25 000 cells/mm3 (OR = 2.35) and blood urea >8 mmol/l (OR = 4.02). Moreover, in children group, a significant association was found between PRISM score and mortality rate, this model had a high discriminative power with an area under the ROC curve at 0.93. In the adult patients a significant association was found between SAPS II score and mortality rate, this model had a high discriminative power with an area under the ROC curve at 0.82. In summary, in severe scorpion envenomation, age less than 5 years, fever >38.5 degrees C, coma with Glasgow coma score < or =8/15, pulmonary edema, leucocytes >25 000 cells/mm3 and blood urea >8 mmol/l were associated with a poor outcome.

Bothrops jararaca venom (BjV) induces differential leukocyte accumulation in mice genetically selected for acute inflammatory reaction: the role of host genetic background on expression of adhesion molecules and release of endogenous mediators

The dynamics of the local inflammatory events induced by Bothrops jararaca venom (BjV) inoculation in footpad of mice genetically selected for maximal (AIRmax) and minimal (AIRmin) acute inflammatory reactivity (AIR) was investigated. The BjV injection induced a marked inflammatory cell infiltrate with predominance of neutrophils, with increased blood cell numbers before its accumulation, suggesting a stimulatory action of BjV on mechanisms of cell mobilization from bone marrow. The process of cell migration is regulated by different cell-adhesion molecules (CAM). Our results showed that neutrophil cells from both lines had the same pattern of response concerning CAMs expression, presenting the involvement of l-selectin, Mac-1 and PECAM-1 adhesion molecules in BjV-induced neutrophil accumulation. The effect of BjV on the release of pro-inflammatory cytokines and chemokines related with cellular migration was also studied and IL-1beta, IL-6, TNF-alpha and MIP-2 levels could be detected after venom injection. The AIRmax mice were shown to be more responsive than AIRmin with respect to leukocyte influx, expression of MIP-2 and release of IL-1beta and IL-6. These results demonstrate the importance of host genetic background in the local response and the involvement of alleles accumulated in AIRmax mice in the inflammatory events induced by BjV.

Pathophysiological effects of Androctonus australis hector scorpion venom: tissue damages and inflammatory response

In this study, the effects of sublethal dose of Androctonus australis hector (Aah) venom on the enzymatic activities (creatine phospho-kinase and lactate dehydrogenase) and histopathological changes of heart and lungs' organs were determined 24h following envenoming NMRI mice. The effects of Aah venom on the lytic activity of the complement system, plasma cytokine rates (IL1-beta, IL-6, TNF-alpha, IL-4 and IL-10) and the peripheral blood cell infiltration were also studied. Microscopically, treated animals showed severe myocardial edema, hemorrhages and necroses and severe acute bronchopneumonia with alveolar edema and hemorrhages. High serum levels of lactate dehydrogenase and creatine kinase correlate to the tissue lesions. The results showed fast kinetics of production of pro-inflammatory (IL1-beta, IL-6, TNF-alpha) and anti-inflammatory (IL-4 and IL-10) cytokines at 30min in blood sera. An increase in serum lytic activity of envenomed animals and leucocytosis in peripheral blood with predominance of mononuclear and neutrophil cells were also observed. In conclusion, the results reported in the present study suggest that pathophysiological manifestations of Aah envenomation may be mediated sequentially or simultaneously by cytokines and the complement system, which in turn activate leukocyte to produce tissue damage.

Biochemical and biological characterization of the venoms of Bothriopsis bilineata and Bothriopsis taeniata (Serpentes: Viperidae)

Snake venom is a complex mixture containing diverse protein components with different structures and functions that are used for prey immobilization and death. Snake venoms from the family Viperidae cause pronounced local and systemic effects, such as pain, edema, hemorrhage and necrosis. Here, we investigated the enzymatic and biological activities of venoms from two Amazonian snakes, Bothriopsis bilineata and Bothriopsis taeniata. Both venoms presented high enzymatic activities for proteases kallikrein, thrombin and plasmin, low levels of trypsin, cathepsin C and leucine aminopeptidase activities, while lacked acetylcholinesterase activity. B. taeniata and B. bilineata crude venoms caused inflammation inducing neutrophil recruitment into peritoneal cavity of mice 4h after injection. Neutrophil recruitment induced by B. taeniata venom was accompanied by hemorrhage. EDTA treatment profoundly impaired neutrophil recruitment, suggesting the involvement of a metalloproteinase on venoms-induced neutrophil recruitment. Pretreatment with dexamethasone and zileuton, a 5-lipoxygenase inhibitor, significantly reduced neutrophil migration, but indomethacin and montelukast, a cysteinyl leukotriene receptor antagonist, had no effect, suggesting the involvement of lipoxygenase-derived metabolites, probably LTB(4). Together, these results show that B. bilineata and B. taeniata venoms induce a marked inflammatory reaction, with leukocyte recruitment, and hemorrhage, which parallels to a high proteolytic activity found in these venoms.

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.

Unusual profile of leukocyte recruitment in mice induced by a skin secretion of the tree frog Phyllomedusa hypochondrialis

Phyllomedusa hypochondrialis skin secretion can cause both systemic and local effects. In this study, we describe the pattern of local acute inflammatory response after P. hypochondrialis skin secretion injection. The inflammatory reaction in the mice footpad was analysed, including the leukocyte recruitment into local tissue from the peripheral blood, in a mouse model of tissue injury. We also investigated the release of the cytokines IL-1, IL-6 and TNF-alpha, chemokines KC and MCP-1 and the eicosanoids LTB 4 and PGE(2) in mice. The present findings support the ability of P. hypochondrialis skin secretion to induce local inflammation. In addition, these skin secretion components play a role in the initial rolling and slowing of recruited leukocytes and the transition from rolling to adhesion. Levels of the proinflammatory cytokine IL-6, chemokines KC and MCP-1 as well as the eicosanoid PGE(2) were significantly increased after injection of a skin secretion of P. hypochondrialis (0.6 microg/30 microl intraplantar), whereas no changes in other parameters were observed. Finally, the mechanisms involved in the local inflammatory process induced by P. hypochondrialis skin secretion is one of the questions of relevance related to the complex pathophysiology induced by this particular secretion and other toxins.

Bothrops jararaca and Crotalus durissus terrificus venoms elicit distinct responses regarding to production of prostaglandins E2 and D2, and expression of cyclooxygenases

Prostaglandins (PGs), synthesized by cyclooxygenases, play important roles in many pathophysiological processes including inflammation and hyperalgesia. In this study the profiles of PGE(2) and PGD(2) production secondary to injection of Bothrops jararaca venom (BjV), with inflammatory activity or Crotalus durissus terrificus venom (CdtV), with anti-inflammatory and antinociceptive properties, into mice were evaluated, and the ability of these venoms to induce expression of cyclooxygenases-1 (COX-1) and -2 (COX-2) was investigated. Intraperitoneal injection of BjV but not of CdtV induced the release and PGD(2) at 30 min and of PGE(2) from 3 up to 12 h after injection. Moreover, BjV up-regulated expression of COX-2 but not of the constitutive COX-1, suggesting that expressed COX-2 provides more substrate for synthesis of PGs by the respective terminal synthases, being the critical enzyme for PGs production in the late periods of BjV effect. In contrast, CdtV does not have any effect on constitutive COX-1 and do not induce expression of COX-2. Therefore, differences between BjV and CdtV in the ability to regulate PGs synthesis can account for their distinct effects with regard to inflammation. Moreover, inhibition of COX-2 by selective drugs may be of value to counteract the severe local inflammation induced by BjV in the victims.

Factors associated with pulmonary edema in severe scorpion sting patients--a multivariate analysis of 428 cases

OBJECTIVE

To determine clinical and routine laboratory factors associated with pulmonary edema secondary to scorpion envenomation.

DESIGN AND SETTING

Retrospective study covering 13 years (1990-2002) in the medical Intensive Care Unit of a university hospital (Sfax-Tunisia).

PATIENTS

428 patients older than 3 years who were admitted to the intensive care unit for scorpion envenomation were included in this study. Patients were stratified into two groups according to the presence or absence of pulmonary edema as assessed by a medical committee.

MEASUREMENTS AND RESULTS

The mean (+/- SD) age was 17.5 +/- 17.7 years, ranging from 3 to 76 years. The pulmonary edema group included 294 patients (68.7%). A multivariate analysis found the following factors to be correlated with a pulmonary edema: age less than 5 years (p = 0.04), sweating (p = 0.004), agitation (p = 0.01), leukocytes of 25000 cells/mm3 or more (p = 0.02), and a plasma protein concentration of 72 g/L or more (p < 0.0001). In addition, a plasma protein concentration of 72 g/L or more predicted the presence of pulmonary edema with a sensitivity of 78% a specificity of 88%, a positive predictive value of 93%, and negative predictive value of 64%. Almost 84% of patients having a respiratory rate of > or = 30 breaths/minute associated with agitation and sweating were classified in the pulmonary edema group. This clinical association indicates the presence of pulmonary edema with a specificity of 84.3% and a positive predictive value of 87.5%.

CONCLUSION

In scorpion envenomation patients older than 3 years, the association of a respiratory rate of > or = 30 breaths/minute, agitation, sweating, or the presence of high plasma protein concentrations suggest the presence of pulmonary edema.

Differential modulation of cell recruitment and acute edema in a model of Polybia paulista venom-induced inflammation

Hymenoptera stings are quite common and can cause inflammatory reactions (in nonallergic individuals) or serious reactions (in allergic individuals). Hymenoptera venom contains histamine, vasoactive kinins, serotonin, phospholipase A, phospholipase B, hyaluronidase, antigen 5 and mastoparans. Some of these substances are responsible for local pain, as well as for activation of complement and endothelial cells. Polybia paulista is a wasp typically found in the state of São Paulo, Brazil. In the present study, we evaluated inflammatory reactions in the peritoneal cavities of rats injected with P. paulista venom (PPV). We evaluated leukocyte recruitment and edema formation at the site of inflammation. After i.p. inoculation with PPV, there was dose-dependent and time-dependent recruitment of neutrophils, eosinophils and mononuclear cells. At 4 to 48 h after stimulus, administration of MK 886, a leukotriene synthesis inhibitor, completely abolished granulocyte recruitment to the peritoneal cavity. Therefore, leukotrienes seem to be the primary mediators of PPV-induced neutrophil and eosinophil recruitment. Inoculation with PPV also induced protein extravasation into the peritoneal cavity. This phenomenon was not inhibited by treatment with MK 886 or indomethacin (a prostaglandin synthesis inhibitor), demonstrating that neither leukotrienes nor prostaglandins are involved in this inflammatory reaction. However, edema formation was significantly inhibited by treatment with pyrilamine, indicating that the histamine H1 receptor plays a critical role in PPV-induced formation of acute edema.