Snake venom cysteine-rich secretory protein from Mojave rattlesnake venom (Css-CRiSP) induces acute inflammatory responses on different experimental models.

Snake venoms contain various molecules known for activating innate immunity and causing local effects associated with increased vascular permeability, such as vascular leakage and edema, common symptoms seen in snakebite envenomings. We have demonstrated that snake venom cysteine-rich secretory proteins (svCRiSPs) from North American pit vipers increase vascular permeability. This study aimed to explore the functional role of CRiSP isolated from Mojave rattlesnake (Crotalus scutulatus scutulatus) venom (Css-CRiSP) on the activation of inflammatory responses in different models. We measured the release of inflammatory mediators in cultured human dermal blood endothelial cells (HDBEC), lymphatic endothelial cells (HDLEC) and monocyte-derived macrophages (MDM) at 0.5, 1, 3, 6, and 24 h after treatment with Css-CRiSP (1 µM). We also determined the acute inflammatory response in BALB/c mice 30 min after intraperitoneal injection of the toxin (2 µg/mouse). Css-CRiSP induced the production of IL-8 and IL-6, but not TNF-α, in HDBEC and HDLEC in a time-dependent manner. In addition, Css-CRiSP significantly enhanced the production of IL-6, TNF-α, IL-8, and IL-1ß in MDM. Moreover, it caused a remarkable increase of chemotactic mediators in the exudates of experimental mice. Our results reveal that Css-CRiSPs can promote a sustained release of inflammatory mediators on cell lines and an acute activation of innate immunity in a murine model. These findings contribute to the growing body of evidence supporting the involvement of svCRiSPs in the augmentation of envenomation effects, specifically, the role of svCRiSPs in inducing vascular dysfunction, initiating early inflammatory responses, and facilitating the activation of leukocytes and releasing mediators. These findings will lead to a better understanding of the pathophysiology of envenoming by Mojave rattlesnakes, allowing the development of more efficient therapeutic strategies.

Proteomic Profiling of Extracellular Vesicles Isolated from Plasma and Peritoneal Exudate in Mice Induced by Crotalus scutulatus scutulatus Crude Venom and Its Purified Cysteine-Rich Secretory Protein (Css-CRiSP).

Increased vascular permeability is a frequent outcome of viperid snakebite envenomation, leading to local and systemic complications. We reported that snake venom cysteine-rich secretory proteins (svCRiSPs) from North American pit vipers increase vascular permeability both in vitro and in vivo. They also induce acute activation of several adhesion and signaling molecules that may play a critical role in the pathophysiology of snakebites. Extracellular vesicles (EVs) have gained interest for their diverse functions in intercellular communication, regulating cellular processes, blood-endothelium interactions, vascular permeability, and immune modulation. They also hold potential as valuable biomarkers for diagnosing, predicting, and monitoring therapeutic responses in different diseases. This study aimed to identify proteins in peritoneal exudate and plasma EVs isolated from BALB/c mice following a 30 min post-injection of Crotalus scutulatus scutulatus venom and its purified CRiSP (Css-CRiSP). EVs were isolated from these biofluids using the EVtrap method. Proteomic analysis of exudate- and plasma-derived EVs was performed using LC-MS/MS. We observed significant upregulation or downregulation of proteins involved in cell adhesion, cytoskeleton rearrangement, signal transduction, immune responses, and vesicle-mediated transports. These findings suggest that svCRiSPs play a crucial role in the acute effects of venom and contribute to the local and systemic toxicity of snakebites.

Evaluation of Signaling Pathways Profiling in Human Dermal Endothelial Cells Treated by Snake Venom Cysteine-Rich Secretory Proteins (svCRiSPs) from North American Snakes Using Reverse Phase Protein Array (RPPA).

Cysteine-Rich Secretory Proteins (CRiSPs) are typically found in many snake venoms; however, the role that these toxins play in the pathophysiology of snakebites is still unclear. Herein, we compared the effects of snake venom CRiSPs (svCRiSPs) from the most medically important species of North American snakes on endothelial cell permeability and vascular permeability. We used reverse phase protein array (RPPA) to identify key signaling molecules on human dermal lymphatic (HDLECs) and blood (HDBECs) endothelial cells treated with svCRiSPs. The results showed that Css-CRiSP isolated from Crotalus scutulatus scutulatus and App-CRiSP from Agkistrodon piscivorus piscivorus are the most potent causes of increase vascular and endothelial permeability in comparison with other svCRiSPs used in this study. We examined the protein expression levels and their activated phosphorylation states in HDLECs and HDBECs induced by App-CRiSP and Css-CRiSP using RPPA. Interestingly, both App-CRiSP and Css-CRiSP induced caveolin-1 expression in HDBECs. We also found that stimulating HDBECs with Css-CRiSP and App-CRiSP significantly induced the phosphorylation of mTOR and Src, respectively. In HDLECs, Css-CRiSP significantly downregulated the expression of N-Cadherin and phospholipase C-gamma, while App-CRiSP significantly enhanced Akt and JNK phosphorylation. These results suggest that the increased endothelial permeability in HDLECs and HDBECs by Css-CRiSP and App-CRiSP may occur through different pathways.

Examination of the Efficacy and Cross-Reactivity of a Novel Polyclonal Antibody Targeting the Disintegrin Domain in SVMPs to Neutralize Snake Venom.

Snake envenomation can result in hemorrhage, local necrosis, swelling, and if not treated properly can lead to adverse systemic effects such as coagulopathy, nephrotoxicity, neurotoxicity, and cardiotoxicity, which can result in death. As such, snake venom metalloproteinases (SVMPs) and disintegrins are two toxic components that contribute to hemorrhage and interfere with the hemostatic system. Administration of a commercial antivenom is the common antidote to treat snake envenomation, but the high-cost, lack of efficacy, side effects, and limited availability, necessitates the development of new strategies and approaches for therapeutic treatments. Herein, we describe the neutralization ability of anti-disintegrin polyclonal antibody on the activities of isolated disintegrins, P-II/P-III SVMPs, and crude venoms. Our results show disintegrin activity on platelet aggregation in whole blood and the migration of the SK-Mel-28 cells that can be neutralized with anti-disintegrin polyclonal antibody. We characterized a SVMP and found that anti-disintegrin was also able to inhibit its activity in an in vitro proteolytic assay. Moreover, we found that anti-disintegrin could neutralize the proteolytic and hemorrhagic activities from crude Crotalus atrox venom. Our results suggest that anti-disintegrin polyclonal antibodies have the potential for a targeted approach to neutralize SVMPs in the treatment of snakebite envenomations.

Biological activities of a new crotamine-like peptide from Crotalus oreganus helleri on C2C12 and CHO cell lines, and ultrastructural changes on motor endplate and striated muscle.

Crotamine and crotamine-like peptides are non-enzymatic polypeptides, belonging to the family of myotoxins, which are found in high concentration in the venom of the Crotalus genus. Helleramine was isolated and purified from the venom of the Southern Pacific rattlesnake, Crotalus oreganus helleri. This peptide had a similar, but unique, identity to crotamine and crotamine-like proteins isolated from other rattlesnakes species. The variability of crotamine-like protein amino acid sequences may allow different toxic effects on biological targets or optimize the action against the same target of different prey. Helleramine was capable of increasing intracellular Ca2+ in Chinese Hamster Ovary (CHO) cell line. It inhibited cell migration as well as cell viability (IC50 = 11.44 µM) of C2C12, immortalized skeletal myoblasts, in a concentration dependent manner, and promoted early apoptosis and cell death under our experimental conditions. Skeletal muscle harvested from mice 24 h after helleramine injection showed contracted myofibrils and profound vacuolization that enlarged the subsarcolemmal space, along with loss of plasmatic and basal membrane integrity. The effects of helleramine provide further insights and evidence of myotoxic activities of crotamine-like peptides and their possible role in crotalid envenomings.

The isolation and characterization of a new snake venom cysteine-rich secretory protein (svCRiSP) from the venom of the Southern Pacific rattlesnake and its effect on vascular permeability.

A novel snake venom cysteine-rich secretory protein (svCRiSP), Hellerin, was purified from C. o. helleri venom using sequential reverse phase and cation-exchange chromatography. Gel electrophoresis, N-terminal sequencing, and LC-MS/MS sequencing identified a single protein with a molecular mass of approximately 24.8 kDa and confirmed its identity as a svCRiSP. Hellerin had cytotoxic effects on human umbilical vein endothelial cells (HUVECs) in a dose-dependent manner but not in human dermal lymphatic endothelial cells (HDLECs) and human dermal blood endothelial cells (HDBECs). Hellerin produced a dramatic increase in both blood vascular permeability in vivo, and in the trans-epithelial permeability of cultured HDLEC and HDBEC cells. This is the first study that describes the effect of a svCRiSP on vascular, blood and lymphatic permeability.

Role of the inflammatory response in the hemorrhagic syndrome induced by the hemolymph of the caterpillar Lonomia achelous.

INTRODUCTION: Contact with the caterpillar of Lonomia achelous causes a hemorrhagic syndrome in humans prompted by two processes, an initial mild DIC that is later masked by overwhelming fibrinolytic activity. Although the venom affects both the hemostatic and inflammatory systems separately, it is not clear whether the hematological and hemostatic disturbances may in part be due to an indirect effect via inflammatory mediators. Here we report results on the crosstalk between these systems, particularly the effect of the pro-inflammatory cytokine TNF-α on hemostatic parameters. MATERIALS AND METHODS: the nitric oxide and TNF-α responses, as well as activation of the coagulation and fibrinolytic systems, were measured in macrophages and endothelial cells treated with Lonomia achelous hemolymph (LAH). The same responses were then determined, in a mouse model of LAH envenomation, after treatment with an anti-TNF-α antibody. RESULTS: Both macrophages and endothelial cells responded strongly to LAH in terms of pro-inflammatory mediator release and fibrinolytic activities as well as pro-coagulant activity (TF activity) in endothelial cells. Treatment with antibody against TNF-α decreased both TNF-α and NO3-/NO2- serum levels in the mice, after LAH injection. Blocking TNF-α also modified significantly the serum levels of plasminogen, fibrinogen and FXIII in mice, as well as decreased TF activity in endothelial cells. CONCLUSIONS: LAH may induce a hemostatic effect through endothelial and macrophage activation. These activated cell release hemostatic enzymes as well as pro-inflammatory mediators, principally TNF-α, that potentiate this release in an autocrine fashion, amplifying the fibrinolytic effect, which may in turn exacerbate the hemorrhagic manifestations. As far as we are aware, this is the first report of the relationship between the hemostatic system and the inflammatory responses in a hemorrhagic syndrome induce by animal secretions.