Bothrops snake venoms and their isolated toxins, an L-amino acid oxidase and a serine protease, modulate human complement system pathways

Ascorbic acid as serine protease inhibitor in lung cancer cell line and human serum albumin

Serine proteases (SPs) are distributed among all living cells accounting for almost one-third of all proteases. Dysregulation of SPs during inflammation and/or infection can result in devastating consequences, such as skin and lung inflammation, neuroinflammation, arthritis, as well as metastasis of cancerous cells. Such activities are tightly regulated by various inhibitors known as serine protease inhibitors (SERPIN). The thermodynamic investigations previously revealed that L-ascorbic acid binds to trypsin more firmly than pepsin and the binding force of L-ascorbic acid is driven by hydrogen bonds and van der Waals forces. However, the physiochemical effects of such interaction on trypsin and/or pepsin have not yet been reported. Ascorbic acid, also known as vitamin C, is one of the essential nutrients and most common food supplements, fortificants, and preservatives. The aim of this study was to explore the inhibitory effects of ascorbic acid on serine proteases at various concentrations on the in-vitro digestion and/or hydrolysis of intercellular matrix of cell monolayer and human serum albumin (HSA). The inhibitory effects of ascorbic on trypsin are investigated by qualitative and quantitative analysis using SDS-PAGE imaging and NIH densitometric software. Upon the addition of ascorbic acid in both indicator systems, the detachment and/or dissociation of cell monolayer and the digestion of HSA were inhibited in the presence of EDTA-Trypsin. The inhibitory effect of ascorbic acid on the digestion of intercellular matrix and/or hydrolysis of HSA showed a dose-dependent trend until it reached the maximum extent of inhibition. At an equal concentration (2.5mg/mL) ascorbic acid and EDTA-Trypsin exhibited the most potent inhibitory effect on the in vitro digestion of protein either in the form of intercellular matrix in cell monolayer and/or HSA respectively. Overall, our results based on two indicator systems strongly indicate that ascorbic acid may function as a serine protease inhibitor (SERPIN) beyond other important functions.

A fingerprint of plasma proteome alteration after local tissue damage induced by Bothrops leucurus snake venom in mice

Bothrops spp. is responsible for about 70% of snakebites in Brazil, causing a diverse and complex pathophysiological condition. Bothrops leucurus is the main species of medical relevance found in the Atlantic coast in the Brazilian Northeast region. The pathophysiological effects involved B. leucurus snakebite as well as the organism's reaction in response to this envenoming, it has not been explored yet. Thus, edema was induced in mice paw using 1.2, 2.5, and 5.0 μg of B. leucurus venom, the percentage of edema was measured 30 min after injection and the blood plasma was collected and analyzed by shotgun proteomic strategy. We identified 80 common plasma proteins with differential abundance among the experimental groups and we can understand the early aspects of this snake envenomation, regardless of the suggestive severity of an ophidian accident. The results showed B. leucurus venom triggers a thromboinflammation scenario where family's proteins of the Serpins, Apolipoproteins, Complement factors and Component subunits, Cathepsins, Kinases, Oxidoreductases, Proteases inhibitors, Proteases, Collagens, Growth factors are related to inflammation, complement and coagulation systems, modulators platelets and neutrophils, lipid and retinoid metabolism, oxidative stress and tissue repair. Our findings set precedents for future studies in the area of early diagnosis and/or treatment of snakebites. SIGNIFICANCE: The physiopathological effects that the snake venoms can cause have been investigated through classical and reductionist tools, which allowed, so far, the identification of action mechanisms of individual components associated with specific tissue damage. The currently incomplete limitations of this knowledge must be expanded through new approaches, such as proteomics, which may represent a big leap in understanding the venom-modulated pathological process. The exploration of the complete protein set that suffer modifications by the simultaneous action of multiple toxins, provides a map of the establishment of physiopathological phenotypes, which favors the identification of multiple toxin targets, that may or may not act in synergy, as well as favoring the discovery of biomarkers and therapeutic targets for manifestations that are not neutralized by the antivenom.

Proteomic Identification and Quantification of Snake Venom Biomarkers in Venom and Plasma Extracellular Vesicles

The global exploration of snakebites requires the use of quantitative omics approaches to characterize snake venom as it enters into the systemic circulation. These omics approaches give insights into the venom proteome, but a further exploration is warranted to analyze the venom-reactome for the identification of snake venom biomarkers. The recent discovery of extracellular vesicles (EVs), and their critical cellular functions, has presented them as intriguing sources for biomarker discovery and disease diagnosis. Herein, we purified EV’s from the snake venom (svEVs) of Crotalus atrox and C. oreganus helleri, and from plasma of BALB/c mice injected with venom from each snake using EVtrap in conjunction with quantitative mass spectrometry for the proteomic identification and quantification of svEVs and plasma biomarkers. Snake venom EVs from C. atrox and C. o. helleri were highly enriched in 5′ nucleosidase, L-amino acid oxidase, and metalloproteinases. In mouse plasma EVs, a bioinformatic analysis for revealed upregulated responses involved with cytochrome P450, lipid metabolism, acute phase inflammation immune, and heat shock responses, while downregulated proteins were associated with mitochondrial electron transport, NADH, TCA, cortical cytoskeleton, reticulum stress, and oxidative reduction. Altogether, this analysis will provide direct evidence for svEVs composition and observation of the physiological changes of an envenomated organism.

Immunomodulatory properties of molecules from animal venoms

The immune system can amplify or decrease the strength of its response when it is stimulated by chemical or biological substances that act as immunostimulators, immunosuppressants, or immunoadjuvants. Immunomodulation is a progressive approach to treat a diversity of pathologies with promising results, including autoimmune disorders and cancer. Animal venoms are a mixture of chemical compounds that include proteins, peptides, amines, salts, polypeptides, enzymes, among others, which produce the toxic effect. Since the discovery of captopril in the early 1980s, other components from snakes, spiders, scorpions, and marine animal venoms have been demonstrated to be useful for treating several human diseases. The valuable progress in fields such as venomics, molecular biology, biotechnology, immunology, and others has been crucial to understanding the interaction of toxins with the immune system and its application on immune pathologies. More in-depth knowledge of venoms' components and multi-disciplinary studies could facilitate their transformation into effective novel immunotherapies. This review addresses advances and research of molecules from venoms that have immunomodulatory properties.

Biomedical applications of snake venom: from basic science to autoimmunity and rheumatology

Snake venoms have components with diverse biological actions that are extensively studied to identify elements that may be useful in biomedical sciences. In the field of autoimmunity and rheumatology, various findings useful for the study of diseases and potential drug development have been reported. The study of disintegrins, proteins that block the action of integrins, has been useful for the development of antiplatelet agents and principles for the development of immunosuppressants and antineoplastics. Several proteins in snake venoms act on the coagulation cascade, activating factors that have allowed the development of tests for the study of coagulation, including Russell's viper venom time, which is useful in the diagnosis of antiphospholipid syndrome. Neurotoxins with either pre- or postsynaptic effects have been used to study neurogenic synapses and neuromuscular plaques and the development of analgesics, muscle relaxants and drugs for neurodegenerative diseases. Various components act by inhibiting cells and proteins of the immune system, which will allow the development of anti-inflammatory and immunosuppressive drugs. This review summarizes the usefulness of the components of snake venoms in the fields of autoimmunity and rheumatology, which can serve as a basis for diverse translational research.

Catechin and epicatechin as an adjuvant in the therapy of hemostasis disorders induced by snake venoms

Snake toxins, such as phospholipases A₂ and proteases, are used as research tools to evaluate biological activities and to understand physiopathological processes of natural compounds better. In the present study, the phenolic compounds catechin and epicatechin were incubated with snake venoms to evaluate their inhibition against different substrates. Catechin and epicatechin exerted inhibitions between 20% and 95% on the activity of phospholipases A₂ present in the venom of Bothrops alternatus. In the hemolytic activity, catechin exerted inhibitions between 20% and 25% in all proportions evaluated on the B. jararacussu venom, whereas epicatechin inhibited 20% of the venom activity. Coagulation induced by B. atrox and B. jararacussu venoms was significantly inhibited by catechin and epicatechin, where the time for coagulation was two to three times higher after previous incubation of the venoms with the compounds. The most significant inhibitions for the proteolytic activity on casein were 17% and 27%, respectively, by both compounds. Catechin inhibited serine protease activity induced by B. atrox venom by 64% and epicatechin by 65%. Regarding B. atrox-induced thrombolysis, catechin exerted 40% inhibition and epicatechin around 30%. The fibrinogen proteolysis was completely inhibited by catechin acting on the B. atrox venom in the proportion of 1:1 and by epicatechin on B. jararacussu venom. Catechin and epicatechin showed promising inhibitory action on proteases and phospholipases A₂ . Therefore, these compounds can be explored as an adjuvant for serum therapy or pharmaceutical purposes, once they act on homologous enzymes that are present in humans.

Complement System Inhibition Modulates the Pro-Inflammatory Effects of a Snake Venom Metalloproteinase

Envenomation by Bothrops snakes causes prominent local effects, including pain, oedema, local bleeding, blistering and necrosis, and systemic manifestations, such as hemorrhage, hypotension, shock and acute renal failure. These snake venoms are able to activate the complement system and induce the generation of anaphylatoxins, whose mechanisms include the direct cleavage of complement components by snake venom metalloproteinases and serine proteinases present in the venoms. A metalloproteinase able to activate the three complement pathways and generate active anaphylatoxins, named C-SVMP, was purified from the venom of Bothrops pirajai. Considering the inflammatory nature of Bothrops venoms and the complement-activation property of C-SVMP, in the present work, we investigated the inflammatory effects of C-SVMP in a human whole blood model. The role of the complement system in the inflammatory process and its modulation by the use of compstatin were also investigated. C-SVMP was able to activate the complement system in the whole blood model, generating C3a/C3a desArg, C5a/C5a desArg and SC5b-9. This protein was able to promote an increase in the expression of CD11b, CD14, C3aR, C5aR1, TLR2, and TLR4 markers in leukocytes. Inhibition of component C3 by compstatin significantly reduced the production of anaphylatoxins and the Terminal Complement Complex (TCC) in blood plasma treated with the toxin, as well as the expression of CD11b, C3aR, and C5aR on leukocytes. C-SVMP was able to induce increased production of the cytokines IL-1β and IL-6 and the chemokines CXCL8/IL-8, CCL2/MCP-1, and CXCL9/MIG in the human whole blood model. The addition of compstatin to the reactions caused a significant reduction in the production of IL-1β, CXCL8/IL-8, and CCL2/MCP-1 in cells treated with C-SVMP. We therefore conclude that C-SVMP is able to activate the complement system, which leads to an increase in the inflammatory process. The data obtained with the use of compstatin indicate that complement inhibition may significantly control the inflammatory process initiated by Bothrops snake venom toxins.

Analysis of effectiveness of Iranian snake antivenom on Viper venom induced effects including analysis of immunologic biomarkers in the Echis carinatus sochureki envenomed victims

Snakebite is an important toxicologic emergency with the potential of triggering local and systemic inflammation. Antivenom has remained the mainstay of treatment for snakebite envenomation. In this study we sought to investigate the effectiveness of Iranian antivenom in a series of 44 viper envenomed patients through analysis of changes in clinical severity and the levels of inflammatory markers. Clinical envenomation severity assessed by snakebite severity score (SSS) and laboratory exams of the patients were recorded before (baseline visit) and after antivenom therapy. During 12-h antivenom therapy, the median (range) score of SSS significantly decreased from 3.5 (2-10) on admission to 1 (0-5) in the last visit (P < 0.001). Moreover, a significant decrease in prothrombin time and international normalized ratio was found (P = 0.006 and 0.008; respectively). Plasma concentrations of interleukin (IL) 1-β, IL-6, IL-8, tumor necrosis factor α (TNF-α), complement hemolytic activity (CH50) were also measured in 10 severely Echis carinatus sochureki envenomed victims and 10 age and gender-matched healthy controls. Except IL-8, the baseline levels of IL-1β, IL-6 and TNF-α in victims were significantly higher than healthy controls (P = 0.005, <0.001 and < 0.001, respectively). Moreover, the baseline level of CH50 was significantly lower in the patients compared to healthy controls (P < 0.001). After 12-h antivenom therapy, the plasma levels of IL-1β, IL-6 and TNF-α significantly decreased (P = 0.032, 0.006 and 0.003, respectively), the levels of IL-8 remained relatively unchanged and the CH50 significantly increased (P = 0.011). Iranian snake antivenom was effective in treating viper bite envenomation as it reversed clinical venom effects and restored near normal underlying inflammatory status. This study is the first to ascertain and report the effectiveness of this antivenom in human subjects.

Kinetic investigations and stability studies of two Bothrops L-amino acid oxidases

Background

L-amino acid oxidases isolated from snake venoms (SV-LAAOs) are enzymes that have great therapeutic potential and are currently being investigated as tools for developing new strategies to treat various diseases, including cancer and bacterial infections. The main objective of this study was to make a brief evaluation of the enzymatic stability of two Bothrops LAAOs, one isolated from Bothrops jararacussu (BjussuLAAO-II) and the other from Bothrops moojeni (BmooLAAO-I) venoms.

Methods and results

The enzymatic activity and stability of both LAAOs were evaluated by microplate colorimetric assays, for which BjussuLAAO-II and BmooLAAO-I were incubated with different L-amino acid substrates, in the presence of different ions, and at different pH ranges and temperatures. BjussuLAAO-II and BmooLAAO-I demonstrated higher affinity for hydrophobic amino acids, such as Phe and Leu. The two enzymes showed high enzymatic activity in a wide temperature range, from 25 to 75 °C, and presented optimum pH around 7.0. Additionally, Zn²⁺, Al³⁺, Cu²⁺ and Ni²⁺ ions negatively modulated the enzymatic activity of both LAAOs. As to stability, BjussuLAAO-II and BmooLAAO-I showed high enzymatic activity for 42 days stored at 4 °C in neutral pH solution. Moreover, the glycan portions of both LAAOs were analyzed by capillary electrophoresis, which revealed that BjussuLAAO-II presented two main glycan portions with relative masses of 7.78 and 8.13 CGU, while BmooLAAO-I showed three portions of 7.58, 7.94 and 8.37 CGU.

Conclusions

Our results showed that, when stored properly, BjussuLAAO-II and BmooLAAO-I present enzymatic stability over a long time period, which is very important to allow the use of these enzymes in pharmacological studies of great impact in the medical field.

Immune drug discovery from venoms

This review catalogues recent advances in knowledge on venoms as standalone therapeutic agents or as blueprints for drug design, with an emphasis on venom-derived compounds that affects the immune system. We discuss venoms and venom-derived compounds that affect total immune cell numbers, immune cell proliferation, immune cell migration, immune cell phenotype and cytokine secretion. Identifying novel compounds that 'tune' the system, up-regulating the immune response during infectious disease and cancer and down-regulating the immune response during autoimmunity, will greatly expand the tool kit of human immunotherapeutics. Targeting these pathways may also open therapeutic options that alleviate symptoms of envenomation. Finally, combining recent advances in venomics with progress in low cost, high-throughput screening platforms will no doubt yield hundreds of prototype immune modulating compounds in the coming years.

A critical review on serine protease: Key immune manipulator and pathology mediator

Proteolytic activity is fundamental to survival, so it is not surprising that all living organisms have proteases, especially seine protease. This enzyme in its numerous isoforms and homologues, constitutes the quintessential offence and defence factors, in the form of surface proteins, secreted molecules, gut digestive enzymes, venom in specialised glands or plant latex, among other manifestations. Occurring as trypsin, chymotrypsin, elastase, collagenase, thrombin, subtilisin etc., it mediates a diverse array of functions, including pathological roles as inflammatory, coagulatory to haemorrhagic. This review emphasizes that despite the superficial differences in mechanisms, most health issues, be they infectious, allergic, metabolic, or neural have a common conduit. This enzyme, in its various glycosylated forms leads to signal misinterpretations, wreaking havoc. However, organisms are endowed with serine protease inhibitors which might restrain this ubiquitous yet deleterious enzyme. Hence, serine proteases-driven pathogenesis and antagonising role of inhibitors is the focal point of this critical review.

Prospection of Effects of Guava Leaves Infusion: Antigenotoxic Action and Enzymatic Inhibition

Several forms of Psidium guajava L. (guava) leaf preparations have been widely used for prevention and treatment of illnesses. However, researches about the protective action of guava's natural products on the genetic material of animal cells is scarce. Accordingly, the aim of this study was to evaluate the antigenotoxic potential of infusions of guava leaves from three cultivars (Pedro Sato, Paluma and Roxa) against DNA damage induced by Doxorubicin (DXR) in human leukocytes, and their effects on enzymatic inhibition. To assess the antigenotoxic potential of these infusions, a comet assay (single cell electrophoresis) was conducted. In addition, their inhibitory potential on phospholipase and hemolytic activities was assessed. The evaluated infusion volumes (25, 50 and 300μL) presented inhibitions around 75% of the DXR-induced damage frequencies. Their protective effect was demonstrated by arbitrary unit calculations, with values between 52.51 and 66.60 for all treatments, 250.51 for positive control (DXR), and 45.49 for phosphate buffered saline (negative control). The infusions significantly inhibited phospholipase and hemolytic activities induced by Bothrops alternatus and B. moojeni venoms, with inhibitions ≥ 50% for both activities induced by B. alternatus. The infusions of P. guajava from the cultivars analyzed present antigenotoxic potential, but also demonstrate potential of enzymatic inhibition on A2phospholipases and proteases.

Characterization of the binding of a glycosylated serine protease from Euphorbia cf. lactea latex to human fibrinogen

In this study, the binding of a glycosylated serine protease (EuP-82) with human fibrinogen was investigated by isothermal titration calorimetry (ITC). ITC analysis indicated that the binding of EuP-82 to fibrinogen in the conditions with or without the activator (Ca²⁺ ) was an exothermic reaction (dominant negative enthalpy), which tended to be driven by hydrogen bonding and van der Waals interactions. In contrast, the binding of fibrinogen-EuP-82 in the condition with the inhibitor (Zn²⁺ ) was an unfavorable endothermic reaction. EuP-82 could not inhibit the platelet activity in citrated whole blood via the ADP-receptor pathways (mainly, P2Y1 and P2Y12), but it could enhance the platelet aggregation. The ITC together with whole blood platelet aggregation suggested that EuP-82 provided multiple fibrinogen-binding sites that were not related to the arginine-glycine-aspartate (RGD) and the dodecapeptide sequences of fibrinogen. In addition, EuP-82 had neither thrombin-like activity nor anticoagulant activity. The SR-FTIR spectra revealed that EuP-82 was a glycoprotein. Deglycosylation of EuP-82 did not affect its proteolytic activity. Moreover, EuP-82 did not exhibit any toxicity to the living cells (NIH-3T3). This study supports that EuP-82 may be useful for wound-healing material through stabilizing the clot via the platelet induction for the first process.

Antithrombotic activity of Batroxase, a metalloprotease from Bothrops atrox venom, in a model of venous thrombosis

BACKGROUND

Snake venoms are great sources of bioactive molecules, which may be used as models for new drugs. Toxins that interfere in hemostasis have received considerable attention over the years.

OBJECTIVES

This study aimed at the evaluation of the antithrombotic activity of Batroxase, a P-I metalloprotease from Bothrops atrox venom, in an animal model of venous thrombosis.

METHODS

The antithrombotic activity of Batroxase was tested in vivo in a model based on two factors of the Virchow's Triad: blood flow alterations (partial stenosis of the inferior vena cava), and vessel wall injury (10% ferric chloride for 5min), in comparison with sodium heparin (positive control) and saline (negative control). Bleeding/clotting time was assessed by a tail bleeding assay. The immunogenicity of Batroxase was also analyzed.

RESULTS

Batroxase (12mg/kg) reduced thrombus formation in 81%, similarly to heparin (100U/kg), which reduced it in 85% in comparison with the saline group. Both Batroxase and heparin increased bleeding/clotting time in approximately 3 fold. Immunizations of rabbits with Batroxase do not result in detectable levels of antibodies against this metalloprotease.

CONCLUSION

Batroxase presents antithrombotic activity in vivo. Moreover, its lack of immunogenicity increases the interest on its possible therapeutic potential over thrombogenic disorders.