Cytotoxicity and morphological analysis of cell death induced by Bothrops venoms from the northeast of Argentina

Potential low-impact immunogen for the production of anti-bothropic serum: Bothrops alternatus venom treated with Na2EDTA

This study proposes an alternative method using Na2EDTA to neutralize B. alternatus venom and using it as an immunogen from the start of inoculation to minimize side effects and enhance antivenom production. To achieve this, 1.8 mg/mL of B. alternatus venom (B.aV) was treated with Na2EDTA, and any extra chelate was eliminated by filtering the resulting solution through a Sephadex G-25 column. Two groups of BALB/c mice were immunized subcutaneously on days 1, 15 and 30 with B.aV/Na2EDTA (45, 90, 135 μg/mouse) or B.aV (15, 30, 45 μg/mouse), respectively. Both formulations were emulsified with Freund's adjuvant (complete first and incomplete-booster). Blood samples were collected from each mouse on days 14, 29, 41, and 50 post-first immunization, and serum was separated for antibody detection. Animals were then sacrificed and lungs removed for histological analysis (hematoxylin-eosin). Immunoblotting analysis revealed that the sera from mice inoculated with B.aV/Na2EDTA (anti-B.aV/Na2EDTA) recognized the major venom proteins (20-66 kDa) similarly to the sera from mice inoculated with B.aV (anti-B.aV). The enzyme-linked immunosorbent assay results indicated that the anti-B.aV/Na2EDTA had a higher titer (5.76 × 104) than those the anti-B.aV (1.92 × 104). Additionally, sera from animals immunized with B.aV/Na2EDTA significantly neutralized proteolytic, indirect hemolytic and coagulant activity (p < 0.05). Finally, histological examination of the lungs of mice inoculated with B.aV/Na2EDTA showed normal appearance, while animals inoculated with B.aV showed interstitial lung injury (p < 0.05). In conclusion, the B.aV/Na2EDTA formulation, free of excess Na2EDTA, proved to be a promising candidate as an immunogen for antivenom production.

Cytoprotective effects of creosote bush (Larrea tridentata) and Southern live oak (Quercus virginiana) extracts against toxicity induced by venom of the black-tailed rattlesnake (Crotalus ornatus)

The venom of Crotalus ornatus (vCo) poses a threat to human health, as it contains a mixture of toxins that can cause cytotoxic, necrotic, and hemolytic effects. The present study assessed methanolic and acetone extracts from leaves and flowers of Larrea tridentata, as well as the bark of Quercus virginiana as potential suppressors of the toxic effects of vCo in vitro. The content of total phenols, flavonoids, and tannins of the plant extracts were quantified for the suppression of vCo cytotoxicity in two cell culture models, human lymphocytes and porcine aortic endothelial (PAE) cells. Extracts from Q. virginiana displayed a greater concentration of total phenols, flavonoids, and tannins. Co-incubation of lymphocytes and PAE cells with fixed concentrations of vCo and plant extracts resulted in decreased vCo-induced cytotoxicity. A 24-hour co-incubation of lymphocytes with vCo (2.36 ± 0.17 µg/mL) and 0.5 µg/mL of methanolic leaf extract from L. tridentata (LLM) significantly suppressed the venom-induced cytotoxicity by 37.33 ± 8.33%. Similarly, the LLM extract (4 µg/mL) caused a significant decrease in vCo cytotoxicity after 24 hours in PAE cells. In contrast, while the acetone extract of Q. virginiana bark (QA) suppressed cytotoxicity by 29.20 ± 3.51% (p < 0.001) in lymphocytes, it failed to protect PAE cells against vCo after 24 hours. In PAE cells, a shorter 4-hour co-incubation showed significant suppression of cytotoxicity with both extracts. Our results collectively suggest that LLM and QA possess cytoprotective properties against the in vitro toxic effects of vCo, and thus establish extracts from these plants as potential therapeutic interventions against Crotalus envenomation.

Venoms and Isolated Toxins from Snakes of Medical Impact in the Northeast Argentina: State of the Art. Potential Pharmacological Applications

Among the ophidians that inhabit the Northeast of Argentina, the genus Bothrops such as B. alternatus and B. diporus species (also known as yararás) and Crotalus durisus terrificus (named cascabel), represent the most studied snake venom for more than thirty years. These two genera of venomous snakes account for the majority of poisonous snake envenomations and therefore, constitute a medical emergency in this region. This review presents a broad description of the compiled knowledge about venomous snakebite: its pathophysiological action, protein composition, isolated toxins, toxin synergism, toxin-antitoxin cross-reaction assays. Properties of some isolated toxins support a potential pharmacological application.

Whole-Cell Multiparameter Assay for Ricin and Abrin Activity-Based Digital Holographic Microscopy

Ricin and abrin are ribosome-inactivating proteins leading to inhibition of protein synthesis and cell death. These toxins are considered some of the most potent and lethal toxins against which there is no available antidote. Digital holographic microscopy (DHM) is a time-lapse, label-free, and noninvasive imaging technique that can provide phase information on morphological features of cells. In this study, we employed DHM to evaluate the morphological changes of cell lines during ricin and abrin intoxication. We showed that the effect of these toxins is characterized by a decrease in cell confluence and changes in morphological parameters such as cell area, perimeter, irregularity, and roughness. In addition, changes in optical parameters such as phase-shift, optical thickness, and effective-calculated volume were observed. These effects were completely inhibited by specific neutralizing antibodies. An enhanced intoxication effect was observed for preadherent compared to adherent cells, as was detected in early morphology changes and confirmed by annexin V/propidium iodide (PI) apoptosis assay. Detection of the dynamic changes in cell morphology at initial stages of cell intoxication by DHM emphasizes the highly sensitive and rapid nature of this method, allowing the early detection of active toxins.

Russell's viper venom affects regulation of small GTPases and causes nuclear damage

Russell's viper with its five sub-species is found throughout the Indian subcontinent. Its venom is primarily hemotoxic. However, its envenomation causes damage to several physiological systems. The present work was aimed to study the dose and time dependent cytotoxic effects of Russell's viper venom (RVV) on human A549 cells grown in vitro. Time dependent changes have been observed in cellular morphology following exposure to RVV. Presence of stress granules, rounding-off of the cells, and formation of punctate structure and loss of cell-cell contact characterized the cellular effects. Fluorescence microscopic studies revealed that apoptotic cell population increased on exposure to RVV. Further to understand the mechanism of these effects, status of small GTPase (smGTPases) expression were studied by Western blot and RT-PCR; as smGTPases play pivotal roles in deciding the cellular morphology, polarity, cell movement and overall signaling cascade. It was shown for the first time that expression patterns of Rac, Rho and CDC42 genes are altered on exposure to RVV. Similarly, significant difference in the expression pattern of HSP70 and p53 at the mRNA levels were noted. Our results confirmed that RVV induces apoptosis in A549 cells; this was further confirmed by AO/EtBr staining as well as caspase-3 assay. All experiments were compared using RVV unexposed cells. We propose for the first time that RVV induces morphological changes in human A549 cells through modulation of smGTPase expression and affects the cellular-nuclear architecture which in turn interferes in proliferation and migration of these cells along with apoptosis.

Phospholipase A(2) enhances the endothelial cell detachment effect of a snake venom metalloproteinase in the absence of catalysis

Microvessel disruption leading to hemorrhage stands among the most dangerous consequences of envenomings by snakes of the family Viperidae. A PIII metalloproteinase (SVMP), balteragin, purified from the venom of the snake Bothrops alternatus, displays a potent hemorrhagic effect, and a moderate myotoxicity in vivo. Previous studies described the ability of this SVMP to induce the detachment of C2C12 myoblasts in culture, without causing cytolysis. Surprisingly, a purified acidic phospholipase A2 (PLA2) from the same venom was found to increase this detaching activity of the SVMP on myoblasts. Since endothelial cells are a natural target of SVMPs in vivo, the possibility that this synergistic effect is also observed on this cell type was explored in the present work. In addition, a first approach of the mechanism of action of this effect was studied. Results clearly confirm that the acidic PLA2, despite lacking toxicity towards endothelial cells, significantly enhances the detaching effect of the SVMP even at a concentration as low as 1 μg/mL. Inhibition of enzymatic activity of the PLA2 by chemical modification with p-bromophenacyl bromide did not affect the synergistic activity, suggesting that this effect is not dependent on phospholipase enzymatic activity and may instead be the consequence of an interaction of the PLA2 with endothelial cell plasma membrane. To our knowledge, this is the first report of a synergistic action of a non toxic PLA2 in enhancing the detachment of endothelial cells induced by a metalloproteinase.

Viper venom induced inflammation with Montivipera xanthina (Gray, 1849) and the anti-snake venom activities of Artemisia absinthium L. in rat

The present study was conducted to explore the characterization of Montivipera xanthina crude venom partially by in vitro and in vivo and the anti-snake venom activities of Artemisia absinthium L. in comparison with carrageenan-induced acute inflammation model in rats. The LD50 value was estimated as 8.78 mg/kg within 24 h by different venom doses administrated intraperitoneally in mice. The IC50 value was 0.43 ± 0.18 μg/ml after 48 h treatment while the calculated value was 0.73 ± 0.10 μg/ml for the culture media totally refreshed after 2 h treatment with venom. Wistar rats were treated intraperitoneally with A. absinthium extract, 30 min before venom or carrageenan was injected subplantarly into the left hind paw. Intraperitoneal administration of 25 and 50 mg/kg extract was inhibited venom induced paw swelling at 0.5, 1, 2 and 3 h (p < 0.05) while 12.5, 25 and 50 mg/kg extract treatment was inhibited carrageenan-induced paw swelling at 2, 3, 4 and 5 h (p < 0.05). In conclusion, the in vivo toxicity and inflammatory actions and in vitro cytotoxic actions of crude M. xanthina venom were performed as a first report and inhibition of venom-induced inflammation by methanolic extract of A. absinthium was described.