Cardioprotective effects of alternagin-C (ALT-C), a disintegrin-like protein from Rhinocerophis alternatus snake venom, on hypoxia-reoxygenation-induced injury in fish.

Alternagin-C (ALT-C) is a disintegrin-like peptide purified from Rhinocerophis alternatus snake venom with the property of inducing vascular endothelial growth factor (VEGF) expression, endothelial cell proliferation and migration, and angiogenesis. Therefore, this protein could be interesting as a new approach for ischemic heart diseases, an imbalance between myocardial oxygen supply and demand, leading to cardiac dysfunction. We investigated the effects of a single dose of alternagin-C (0.5 mg kg-1, via intra-arterial), after 7 days, on hypoxia/reoxygenation challenge in isolated ventricle strips and on morphological changes and density of blood vessels of the heart, using fish as an alternative experimental model. ALT-C treatment provided protection of cardiomyocytes against hypoxia/reoxygenation-induced negative inotropism. ALT-C also stimulated angiogenesis and improved excitation-contraction coupling during hypoxic conditions. Our results provide a new insight into a functional role of ALT-C against hypoxia/reoxygenation-induced cardiomyocyte injury pointing out to a potential therapeutic strategy for ischemia-related diseases.

ASP49-phospholipase A2-loaded liposomes as experimental therapy in cutaneous leishmaniasis model.

This study aimed to evaluate the in vivo anti-Leishmania amazonensis activity of a Phospholipase A2 (Asp49-PLA2), isolated from Bothrops jararacussu venom, encapsulated in liposomes as a modified toxin release system. The activity of the liposomes was evaluated in BALB/c mice, previously infected with 1×105 of the parasite's promastigotes. The size of the paw lesion in Asp49-PLA2-liposomal-treated animals, after 21days, was observed as decreasing by 16% relative to the untreated control group and 12% by the Glucantime®-treated animals, which was used as a reference drug. At the end of the treatment, the animals were sacrificed and the paw and lymph node tissues were collected. Part of the collection was used to recover amastigotes and another to quantify cytokines and nitrites. In the group treated with Asp49-PLA2-liposomes the parasitic load was observed to be reduced by 73.5% in the macerated lymph node, compared to the control group. Comparatively, in the paw tissue was observed a reduction of 57.1%. The infected groups treated with Asp49-PLA2-liposomes showed significant production in TNF-α measured in lymph nodes and paw (43.73pg/mL±2.25 and 81.03pg/mL±5.52, respectively) and nitrite levels (31.28µM±0.58 and 35.64µM±5.08) also measured in lymph nodes and paw tissues, respectively, compared to untreated groups. These results indicate that the Asp49-PLA2-loaded liposomes were able to activate the production of some cellular components of the protective TH1 response during the infection, constituting a promising tool for inducing the microbicidal activity of the Leishmania-infected macrophages.

Cathelicidin-WA polarizes E. coli K88-induced M1 macrophage to M2-like macrophage in RAW264.7 cells.

Immune cells - macrophages induced by E. coli K88 will lead to a pro-inflammatory response, which is important in host defense. Cathelicidin-WA (CWA) is an efficient antimicrobial peptide (AMP) and can exert immunomodulatory properties. Many studies have demonstrated that AMP can modulate cellular subsets but whether CWA can regulate macrophage polarization by transferring E. coli K88-induced M1 macrophage towards M2 one that of anti-inflammation remains unclear. In this study, E. coli K88 increased the expression of pro-inflammatory cytokines interleukin-6, interleukin-1ß, tumor necrosis factor-α and chemokine CCL3 in RAW264.7 cells with a time-dependent manner, as well as the expression of reactive oxygen species (ROS) and inducible nitric oxide synthase (iNOS). On this basis, CWA significantly decreased the pro-inflammatory molecules but increased the anti-inflammatory mediators interleukin-4, interleukin-10 and other M2-related genes in E. coli K88-induced macrophages. Western blot analysis indicated that CWA suppressed the expression of TLR-4 and the phosphorylation of STAT1 and NF-κB which modulated M1 macrophage while induced the phosphorylation of STAT6 which activated M2 macrophage. Double staining of M1-specific CD86 and M2-specific CD206 also proved the hypothesis. These results suggested that CWA might dampen the inflammation by modulating M1 phenotype to M2 phenotype in E. coli K88-induced macrophages.

Anti-osteoarthritic activity of Bungarus fasciatus venom fraction BF-F47 involving molecular markers in the rats.

A heat stable protein BF-F47 was purified from the crude venom of Bungarus fasciatus by CM cellulose ion exchange chromatography and HPLC. Osteoarthritis (OA) was developed in male albino Wistar rats by collagenase injection. BF-F47 treatment significantly restored urinary hydroxyproline and glucosamine in OA rats. Serum acid phosphatase, alkaline phosphatase, creatinine and serum molecular markers TNF-α, IL-1ß, IL-17, cytokine induced neutrophil chemoattractant-1, matrix metalloproteinase-1, cathepsin-K, osteocalcin and PGE2 were also significantly altered. BF-F47 showed partial restoration of osteoarthritis joints. Thus, BF-F47 induced anti-osteoarthritic activity in Wistar rats acted through molecular markers of arthritis and inflammation.

Cloning, Characterization and Anti-Inflammatory Properties of Bothrops jararaca Snake Antithrombin.

Antithrombin inhibits blood coagulation through the interaction with serine proteases in both intrinsic and extrinsic pathways. In addition, antithrombin also shows anti-inflammatory properties, which are independent of its effects on coagulation. This work shows for the first time the cloning and sequencing of antithrombin from a snake species. This predicted protein is composed by 430 amino acids and presents about 64.5% sequence identity to human antithrombin. Biacore experiments revealed that the binding affinity of Bothrops jararaca snake antithrombin to heparin was ~30 times higher than that of human antithrombin. Furthermore, Bothrops jararaca antithrombin is more effective in preventing acute inflammation induced by carrageenan when compared to human antithrombin. Hence, the results showed herein suggest that Bothrops jararaca antithrombin can play a key role in the control of acute inflammation and that this molecule might be used as a pharmacological tool and as a prototype for drug development.

The therapeutic potential of a venomous lizard: the use of glucagon-like peptide-1 analogues in the critically ill.

Glucagon-like peptide-1 (GLP-1), a principal mediator of the postprandial insulinotropic response in health, has a half-life of minutes. The saliva of the Gila monster contains exendin-4, a structural analogue of human GLP-1, but with a much longer half-life. A synthetic preparation of exendin-4, exenatide, is suitable for human use and effectively lowers glucose in ambulant type 2 diabetic patients. When compared with insulin, exenatide therapy is associated with a reduction in hypoglycaemic episodes and postprandial glycaemic excursions in this group. Accordingly, GLP-1 analogues are appealing therapies for hyperglycaemia in the critically ill patient and warrant further study.

Structure-function relationship of king cobra cathelicidin.

King cobra cathelicidin (OH-CATH) is composed of 34 amino acid residues having strong antibacterial and very weak hemolytic activities as reported by us recently. OH-CATH can be served as a valuable template to develop novel therapeutic drugs. In this study, OH-CATH and six of its analogs were synthesized to explore their structure-function relationships based on their bactericidal and hemolytic activities. Experimental results of OH-CATH(3-34) and OH-CATH(5-34) indicated that the N-terminal 4 amino acid residues of OH-CATH played an important role on its hemolytic activity but had weak effects on its bactericidal activity. Among OH-CATH and its analogs, OH-CATH(5-34) had the lowest hemolytic activity while maintained strong antimicrobial activity. To evaluate its potential usage, the biological activities of OH-CATH(5-34) were compared with those of pexiganan. The bactericidal activity of OH-CATH(5-34) against 5 different species (11 laboratory strains) was 2-4 times stronger than that of pexiganan (4-16 microg/ml vs 8-32 microg/ml). Hemolytic activity of OH-CATH(5-34) against human erythrocytes was 0.69% while that of pexiganan was 16.5% at the dosage of 200 microg/ml. OH-CATH(5-34) showed very weak cytotoxic activities against primary rabbit ventricular endothelial cells and four human cancer cell lines whereas pexiganan showed strong cytotoxic activity against these five cell lines (IC(50)=20-90 microg/ml). The intravenous LD(50) value of OH-CATH(5-34) on mice was 7-fold higher than that of pexiganan (175 mg/kg vs 25mg/kg). Taken together, our results suggested that OH-CATH(5-34) should be considered as an excellent candidate for developing therapeutic drugs.

Low-molecular-mass peptides from the venom of the Amazonian viper Bothrops atrox protect against brain mitochondrial swelling in rat: potential for neuroprotection.

The neurodegenerative diseases are important causes of morbidity and mortality in Western countries. Common mechanisms of toxicity involving mitochondrial damage have been suggested; however, a definitive treatment has not yet been found. Therefore, there has been great interest in the development of mitochondria-targeted protective compounds for the treatment of neuropathies. Animal toxins represent a promising source of new molecules with neuroprotective activity and potential to originate new drugs. We present here the effects of a low-molecular-mass peptides fraction (Ba-V) from Bothrops atrox snake venom, on rat brain mitochondrial function. Ba-V did not induce the mitochondrial swelling and moreover, was as effective as cyclosporin A (CsA) to inhibit the calcium/phosphate-induced swelling, which indicates its potential to prevent the mitochondrial permeability transition (MPT). The membrane electrochemical potential, the oxygen consumption during states-3 and -4 respirations as well as the respiratory control ratio (RCR) were not affected by Ba-V. Additionally, Ba-V did not induce reactive oxygen species (ROS) generation. Interestingly, Ba-V did not protect against the generation of ROS induced by t-BOH, which suggests a protection mechanism other than ROS scavenging. Given the important role of the mitochondrial damage and, more specifically, of MPT, in the development of neuropathies, Ba-V might be useful in the future strategies for the treatment of these diseases.

Hemostatic properties of a venomic protein in rat organ trauma.

Previous in vitro work characterized the protease Q8009 isolated from the venom of the Australian brown snake Pseudonaja textilis textilis with Factor Xa-like activity and hemostatic properties. The purpose of the work described here characterizes the in vivo hemostatic properties in a rat model of parenchymatous organ injury. The key parameters of activity included reduction in time-to-hemostasis and total volume of blood loss in spleen, liver and kidney wound models in rats. The surgical protocols involved exposure of the organs via a midline abdominal laparotomy. Using a clean metal template with 6, 6.5, 9 mm holes for spleen, liver and kidney, respectively, a predetermined volume of the organ was gently extruded through the template hole and excised with a razor blade. About 50 to 75 microL of collagen matrix with the different test solutions was applied to the wounds. Blood was collected and at the end of the procedure animals were humanely sacrificed with an anesthetic overdose. Determination of blood was performed using the hematin assay using a standard curve. Blood loss per minute and total blood loss were calculated. Results from the studies demonstrated that the application of Q8009 and collagen matrix to surgical wounds significantly reduced the total amount of blood loss and the time-to-hemostasis. In the spleen wound model, Q8009 at 100, 250 and 1000 microg/ml significantly reduced (p<0.001) the total volume of blood lost relative to thrombin and reduced the time-to-hemostasis by 25-50%, as compared to 7% by thrombin. In the liver wound model, Q8009 at 250 and 1000 microg/ml significantly reduced (p<0.001) the total volume of blood lost relative to thrombin and reduced the time-to-hemostasis from 10.5 min by thrombin to 5.6 min with Q8009. In the kidney wound model, Q8009 at 250 microg/ml significantly reduced (p<0.05) the total volume of blood lost and reduced the time-to-hemostasis by 25% when compared to thrombin. The hemostasis levels were consistent with previous findings in skin wound rat models where Q8009 consistently reduced the total volume of blood lost and shortened time-to-hemostasis. Application of Q8009 plus collagen matrix significantly reduced the volume of total blood loss and time-to-hemostasis in rat surgical organ wound models induced bleeding, as compared to a commercially available hemostat device. The protein Q8009 has greater capacity to reduce blood loss and shorten time-to-hemostasis; highly desirable properties where rapid hemostasis is needed in surgical wounds in parenchymatous organs.