Interaction of Bothrops jararaca venom metalloproteinases with protein inhibitors

Systemic Effects of Hemorrhagic Snake Venom Metalloproteinases: Untargeted Peptidomics to Explore the Pathodegradome of Plasma Proteins

Hemorrhage induced by snake venom metalloproteinases (SVMPs) is a complex phenomenon that involves capillary disruption and blood extravasation. HF3 (hemorrhagic factor 3) is an extremely hemorrhagic SVMP of Bothrops jararaca venom. Studies using proteomic approaches revealed targets of HF3 among intracellular and extracellular proteins. However, the role of the cleavage of plasma proteins in the context of the hemorrhage remains not fully understood. The main goal of this study was to analyze the degradome of HF3 in human plasma. For this purpose, approaches for the depletion of the most abundant proteins, and for the enrichment of low abundant proteins of human plasma, were used to minimize the dynamic range of protein concentration, in order to assess the proteolytic activity of HF3 on a wide spectrum of proteins, and to detect the degradation products using mass spectrometry-based untargeted peptidomics. The results revealed the hydrolysis products generated by HF3 and allowed the identification of cleavage sites. A total of 61 plasma proteins were identified as cleaved by HF3. Some of these proteins corroborate previous studies, and others are new HF3 targets, including proteins of the coagulation cascade, of the complement system, proteins acting on the modulation of inflammation, and plasma proteinase inhibitors. Overall, the data indicate that HF3 escapes inhibition and sculpts the plasma proteome by degrading key proteins and generating peptides that may act synergistically in the hemorrhagic process.

Bacterial expression of a snake venom metalloproteinase inhibitory protein from the North American opossum (D.virginiana)

A variety of opossum species are resistant to snake venoms due to the presence of antihemorrhagic and antimyotoxic acidic serum glycoproteins that inhibit several toxic venom components. Two virtually identical antihemorrhagic proteins isolated from either the North American opossum (D. virginiana) or the South American big-eared opossum (D. aurita), termed oprin or DM43 respectively, inhibit specific snake venom metalloproteinases (SVMPs). A better understanding of the structure of these proteins may provide useful insight to determine their mechanism of action and for the development of therapeutics against the global health concern of snake-bite envenomation. The aim of this work is to produce a recombinant snake venom metalloproteinase inhibitor (SVMPI) similar to the above opossum proteins in Escherichia coli and determine if this bacterially produced protein inhibits the proteolytic properties of Western Diamondback rattlesnake (C. atrox) venom. The resulting heterologous SVMPI was produced with either a 6-Histidine or maltose binding protein (MBP) affinity tag on either the C-terminus or N-terminus of the protein, respectively. The presence of the solubility enhancing MBP affinity tag resulted in significantly more soluble protein expression. The inhibitory activity was measured using two complementary assays and the MBP labeled SVMPI showed 7-fold less activity as compared to the 6-Histidine labeled SVMPI. Thus, the bacterially derived SVMPI with an unlabeled N-terminus showed high inhibitory activity (IC₅₀ = 4.5 μM). The use of a solubility enhancing MBP fusion protein construct appears to be a productive way to express sufficient quantities of this mammalian protein in E. coli for further study.

Cleavage of proteoglycans, plasma proteins and the platelet-derived growth factor receptor in the hemorrhagic process induced by snake venom metalloproteinases

Envenoming by viperid snakes results in a complex pattern of tissue damage, including hemorrhage, which in severe cases may lead to permanent sequelae. Snake venom metalloproteinases (SVMPs) are main players in this pathogenesis, acting synergistically upon different mammalian proteomes. Hemorrhagic Factor 3 (HF3), a P-III class SVMP from Bothrops jararaca, induces severe local hemorrhage at pmol doses in a murine model. Our hypothesis is that in a complex scenario of tissue damage, HF3 triggers proteolytic cascades by acting on a partially known substrate repertoire. Here, we focused on the hypothesis that different proteoglycans, plasma proteins, and the platelet derived growth factor receptor (PDGFR) could be involved in the HF3-induced hemorrhagic process. In surface plasmon resonance assays, various proteoglycans were demonstrated to interact with HF3, and their incubation with HF3 showed degradation or limited proteolysis. Likewise, Western blot analysis showed in vivo degradation of biglycan, decorin, glypican, lumican and syndecan in the HF3-induced hemorrhagic process. Moreover, antithrombin III, complement components C3 and C4, factor II and plasminogen were cleaved in vitro by HF3. Notably, HF3 cleaved PDGFR (alpha and beta) and PDGF in vitro, while both receptor forms were detected as cleaved in vivo in the hemorrhagic process induced by HF3. These findings outline the multifactorial character of SVMP-induced tissue damage, including the transient activation of tissue proteinases, and underscore for the first time that endothelial glycocalyx proteoglycans and PDGFR are targets of SVMPs in the disruption of microvasculature integrity and generation of hemorrhage.

Deep Profiling of the Cleavage Specificity and Human Substrates of Snake Venom Metalloprotease HF3 by Proteomic Identification of Cleavage Site Specificity (PICS) Using Proteome Derived Peptide Libraries and Terminal Amine Isotopic Labeling of Substrates (TAILS) N-Terminomics

Snakebite is a major medical concern in many parts of the world with metalloproteases playing important roles in the pathological effects of Viperidae venoms, including local tissue damage, hemorrhage, and coagulopathy. Hemorrhagic Factor 3 (HF3), a metalloprotease from Bothrops jararaca venom, induces local hemorrhage and targets extracellular matrix (ECM) components, including collagens and proteoglycans, and plasma proteins. However, the full substrate repertoire of this metalloprotease is unknown. We report positional proteomic studies identifying >2000 N-termini, including neo-N-termini of HF3 cleavage sites in mouse embryonic fibroblast secretome proteins. Terminal amine isotopic labeling of substrates (TAILS) analysis identified a preference for Leu at the P1' position among candidate HF3 substrates including proteins of the ECM and focal adhesions and the cysteine protease inhibitor cystatin-C. Interestingly, 190 unique peptides matched to annotated cleavage sites in the TopFIND N-termini database, suggesting that these cleavages occurred at a site prone to cleavage or might have been generated by other proteases activated upon incubation with HF3, including caspases-3 and -7, cathepsins D and E, granzyme B, and MMPs 2 and 9. Using Proteomic identification of cleavage site specificity (PICS), a tryptic library derived from THP-1 monocytic cells was used as HF3 substrates for identifying protease cleavage sites and sequence preferences in peptides. A total of 799 unique cleavage sites were detected and, in accordance with TAILS analysis using native secreted protein substrates of MEF cells, revealed a clear preference for Leu at P1'. Taken together, these results greatly expand the known substrate degradome of HF3 and reveal potential new targets, which may serve as a basis to better elucidate the complex pathophysiology of snake envenomation.

Bradykinin-potentiating PEPTIDE-10C, an argininosuccinate synthetase activator, protects against H2O2-induced oxidative stress in SH-SY5Y neuroblastoma cells

Bradykinin-potentiating peptides (BPPs - 5a, 7a, 9a, 10c, 11e, and 12b) of Bothrops jararaca (Bj) were described as argininosuccinate synthase (AsS) activators, improving l-arginine availability. Agmatine and polyamines, which are l-arginine metabolism products, have neuroprotective properties. Here, we investigated the neuroprotective effects of low molecular mass fraction from Bj venom (LMMF) and two synthetic BPPs (BPP-10c, <ENWPHPQIPP; BPP-12b, <EWGRPPGPPIPP) in the SH-SY5Y cell line against H₂O₂-induced oxidative stress. The neuroprotective effects against H₂O₂-induced were analyzed by reactive oxygen species (ROS - DCFH) production; lipid peroxidation (TBARS); intracellular GSH; AsS, iNOS, and NF-kB expressions; nitrite levels (Griess); mitochondrial membrane potential (TMRM); and antioxidant activity (DPPH). Analysis of variance followed by Tukey's post hoc test were calculated for statistical comparisons. Pre-treatment with both BPPs significantly reduced cell death induced by H₂O₂, but BPP-10c showed higher protective capacity than BPP-12b. LMMF pretreatment was unable to prevent the reduction of cell viability caused by H₂O₂. The neuroprotective mechanism of BPP-10c against oxidative stress was investigated. BPP-10c reduced ROS generation and lipid peroxidation in relation to cells treated only with H₂O₂. BBP-10c increased AsS expression and was not neuroprotective in the presence of MDLA, a specific inhibitor of AsS. BPP-10c reduced iNOS expression and nitrate levels but decreased NF-kB expression. Furthermore, BPP-10c protected the mitochondrial membrane against oxidation. Overall, we demonstrated for the first time neuroprotective mechanisms of BPPs against oxidative stress, opening new perspectives to the study and application of these peptides for the treatment of neurodegenerative diseases.

[Public production as a key factor for access to antivenoms in the Region of the Americas]

Los accidentes causados por animales ponzoñosos afectan vastas zonas de América Latina, Sur de Asia, Sudeste Asiático, África subsahariana y Oceanía y representan un serio problema para la salud pública mundial. A partir de un análisis del panorama actual en materia de producción global de los antivenenos ofídicos y aracnídicos, se concluye que son productos semi-huérfanos. Esta situación plantea un escenario favorable para fortalecer su producción por parte de los laboratorios públicos. Los gobiernos deberán tomar una decisión política al respecto en aras de la equidad en la salud de la población. En la Región de las Américas, estas acciones podrían enmarcarse en un programa liderado por la Organización Panamericana de la Salud, para garantizar la disponibilidad de estos productos biológicos en centros asistenciales estratégicamente localizados. Se han identificado 12 establecimientos públicos productores de antivenenos en la Región entre los cuales los de Brasil y México son los mayores productores públicos. La gestión de estos laboratorios debe ser la propia de una organización industrial productora de bienes tangibles que no soslaye la planificación estratégica. Las autoridades regulatorias nacionales deberían ayudar a los laboratorios públicos que los producen prestándoles asesoramiento y consultoría sin perder la imparcialidad ni el rigor necesarios en la evaluación de sus sistemas de gestión de la calidad. Las nuevas tecnologías superiores de la producción a partir de plasma hiperinmune de mamíferos se encuentran en fase experimental. No se ha encontrado en la bibliografía información sobre su incorporación en las líneas de producción.

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.

Unraveling the distinctive features of hemorrhagic and non-hemorrhagic snake venom metalloproteinases using molecular simulations

Snake venom metalloproteinases are important toxins that play fundamental roles during envenomation. They share a structurally similar catalytic domain, but with diverse hemorrhagic capabilities. To understand the structural basis for this difference, we build and compare two dynamical models, one for the hemorrhagic atroxlysin-I from Bothrops atrox and the other for the non-hemorraghic leucurolysin-a from Bothrops leucurus. The analysis of the extended molecular dynamics simulations shows some changes in the local structure, flexibility and surface determinants that can contribute to explain the different hemorrhagic activity of the two enzymes. In agreement with previous results, the long Ω-loop (from residue 149 to 177) has a larger mobility in the hemorrhagic protein. In addition, we find some potentially-relevant differences at the base of the S1' pocket, what may be interesting for the structure-based design of new anti-venom agents. However, the sharpest differences in the computational models of atroxlysin-I and leucurolysin-a are observed in the surface electrostatic potential around the active site region, suggesting thus that the hemorrhagic versus non-hemorrhagic activity is probably determined by protein surface determinants.

The red seaweed Plocamium brasiliense shows anti-snake venom toxic effects

BACKGROUND

Snakebite is considered a neglected tropical disease by the World Health Organization. In Brazil, about 70% of the envenomation cases are caused by Bothrops snakes. Its venom may provoke hemorrhage, pain, necrosis, hemolysis, renal or cardiac failure and even death in victims. Since commercial antivenom does not efficiently neutralize the local toxic effects of venoms, natural products have been tested in order to provide alternative or complementary treatment to serum therapy. Therefore, the present study aimed to evaluate the ability of the seaweed Plocamium brasiliense and its active derivatives to neutralize hemorrhagic, edematogenic, hemolytic, coagulant and proteolytic activities of B. jararaca venom.

METHODS

Specimens of P. brasiliense were collected in Rio de Janeiro state, Brazil, dried and submitted to oil extraction using four solvents of increasing polarities, n-hexane (HEX), dichloromethane (DCM), ethyl acetate (ETA) and hydroalcoholic solution (HYD). The solvents were evaporated, yielding HEX, DCM, ETA and HYD extracts. Further, all extracts were dissolved in dimethylsulfoxide. In addition, two monoterpenes (8-bromo-3,4,7-trichloro-3,7-dimethyl-1E, 5E-octadiene and 1,8-dibromo-3,4,7-trichloro-3,7-dimethyl-1E, 5E-octadiene) and a cholesterol fraction were isolated from the extract of P. brasiliense prepared in hexane. Algal samples were incubated for 30 minutes with B. jararaca venom, and then tested for lethality; hemorrhagic, edematogenic, hemolytic, coagulant and proteolytic effects.

RESULTS

Most of the algal extracts inhibited the toxic effects with different potencies. The DCM extract was the most effective, since it inhibited all types of toxic activity. On the other hand, the HYD extract failed to inhibit any effect. Moreover, the isolated products inhibited proteolysis and protected mice from hemorrhage in 30% of the cases, whereas 8-bromo-3,4,7-trichloro-3,7-dimethyl-1E, 5E-octadiene inhibited 100% and 20% of the hemorrhagic and proteolytic activities, respectively. None of the algal products were toxic to mice.

CONCLUSION

Seaweeds may be a promising source of inhibitors against toxic effects caused by B. jararaca envenomation, which may contribute to antivenom treatment.