Angiogenenic effects of BpLec, a C-type lectin isolated from Bothrops pauloensis snake venom

Animal venoms: a novel source of anti-Toxoplasma gondii drug candidates

Toxoplasma gondii (T. gondii) is a nucleated intracellular parasitic protozoan with a broad host selectivity. It causes toxoplasmosis in immunocompromised or immunodeficient patients. The currently available treatments for toxoplasmosis have significant side effects as well as certain limitations, and the development of vaccines remains to be explored. Animal venoms are considered to be an important source of novel antimicrobial agents. Some peptides from animal venoms have amphipathic alpha-helix structures. They inhibit the growth of pathogens by targeting membranes to produce lethal pores and cause membrane rupture. Venom molecules generally possess immunomodulatory properties and play key roles in the suppression of pathogenic organisms. Here, we summarized literatures of the last 15 years on the interaction of animal venom peptides with T. gondii and attempt to explore the mechanisms of their interaction with parasites that involve membrane and organelle damage, immune response regulation and ion homeostasis. Finally, we analyzed some limitations of venom peptides for drug therapy and some insights into their development in future studies. It is hoped that more research will be stimulated to turn attention to the medical value of animal venoms in toxoplasmosis.

Schinus terebinthifolia Raddi leaf lectin is an antiangiogenic agent for Coturnix japonica embryos

Angiogenesis (budding of new blood vessels) is involved in several processes, including the development of embryos and growth of tumors. Schinus terebinthifolia leaves express an antitumor lectin (SteLL). This work hypothesized that SteLL can interfere with the formation of a vascular network from preexisting vessels. To test this hypothesis, the effect of SteLL on the angiogenesis process was assessed using an in vivo model of yolk sac membrane of Coturnix japonica embryos. SteLL was isolated with purification factor of 46.6. As expected, polyacrylamide gel electrophoresis (PAGE) for native basic proteins confirmed the homogeneity and PAGE in presence of dodecyl sodium sulphate revealed a single 14-kDa polypeptide band. The fractal analysis by box counting and information dimension measurements indicated that SteLL at 1.35 mg/mL significantly decreased by ca. 12% the angiogenesis within the C. japonica yolk sac membrane regarding the control. The inhibition of the vascular network formation in the yolk sac membrane resulted in decreased blood supply to the embryos. Consequently, the area of embryos was significantly reduced by 9.2% regarding the control, which corroborated with the antiangiogenic activity of SteLL. The findings implicate SteLL as an antiangiogenic agent and add to the panel of biological activities of this lectin.

Sesquiterpene Polygodial from Drimys brasiliensis (Winteraceae) Down-Regulates Implant-Induced Inflammation and Fibrogenesis in Mice

Drimys brasiliensis (Winteraceae) has been investigated in traditional medicine for its anti-inflammatory properties to treat gastric ulcers and allergic and respiratory system diseases as well as for cancer treatment. In this work, we investigate the ability of the sesquiterpene polygodial, isolated from D. brasiliensis stem barks, to modulate the chronic inflammatory response induced by polyester-polyurethane sponge implants in C57BL/6J mice. Daily treatment with polygodial inhibited the macrophage content in the implants as determined by the activity of the N-acetyl-β-d-glucosaminidase enzyme as well as decreased the levels of CXCL1/KC and CCL2/JE/MCP-1 pro-inflammatory chemokines and the presence of mast cells along the formed fibrovascular tissue. Similarly, the deposition of a new extracellular matrix (total collagen and type I and III collagen fibers) as well as the production of the TGF-β1 cytokine were attenuated in implants treated with polygodial, showing for the first time its antifibrogenic capacity. The hemoglobin content, the number of newly formed vessels, and the levels of VEGF cytokine, which were used as parameters for the assessment of the neovascularization of the implants, did not change after treatment with polygodial. The anti-inflammatory and antifibrogenic effects of polygodial over the components of the granulation tissue induced by the sponge implant indicate a therapeutic potential for the treatment of inflammatory diseases associated with the development of fibrovascular tissue.

Dehydrodieugenol B and hexane extract from Endlicheria paniculata regulate inflammation, angiogenesis, and collagen deposition induced by a murine sponge model

The present study reports the evaluation of hexane extract from Endlicheria paniculata and its main metabolite dehydrodieugenol B in the inflammatory response induced by a murine implant sponge model. As a result, a reduction in the inflammatory markers (myeloperoxidase and N-acetyl-β-D-glucosaminidase) and number of mast cells were observed in comparison to the control group. All doses were also able to reduce angiogenic parameters evaluated in fibrovascular tissue. In implants treated with dehydrodieugenol B a reduction in total collagen deposition and types I and III collagen fibers were observed, while an increased in total collagen deposition and types I and III collagen fibers were observed in the treatment with hexane extract. Docking studies into cyclooxygenase-2 active site revealed that the dehydrodieugenol B had binding modes and energies comparable with celecoxib, diclofenac and ibuprofen. Therefore, dehydrodieugenol B was able to alter key components of chronic inflammation, resulting in a reduced inflammatory response and also presenting antifibrogenic and antiangiogenic effects. However, treatment with hexane extract resulted in a reduced inflammatory response with antiangiogenic effects, but caused fibrogenic effects.

Alternagin-C, a disintegrin-like protein from Bothrops alternatus venom, attenuates inflammation and angiogenesis and stimulates collagen deposition of sponge-induced fibrovascular tissue in mice

Alternagin-C (ALT-C), a disintegrin-like protein obtained from the venom of Bothrops alternatus, is able to modulate cellular behaviors such as adhesion, migration and proliferation, as well as the production of various growth factors via α₂β₁ integrin, important processes during inflammation, angiogenesis and fibrogenesis, which although appear as distinct events, act concomitantly in several chronic inflammatory diseases. Our objective was to investigate the effects of ALT-C on components of the sponge-induced inflammatory response in balb/c mice. The polyester-polyurethane sponges were implanted in mice's subcutaneous layer of the dorsal region and daily injected with saline (control group) or ALT-C (10, 100 or 1000 ng). Nine days after implantation the implants were removed and processed. ALT-C inhibited the inflammatory response, observed through mast cell reduction, NAG-activity and also by the inhibition of TNF-α, CXCL-1 and CCL2/JE/MCP-1 cytokines. ALT-C was also able to reduce hemoglobin content, number of vessels and the concentrations of VEGF and FGF cytokines. Finally, at its highest dose (1000 ng), ALT-C increased all evaluated markers associated with fibrogenesis (collagen production and TGF-β1 levels). All these factors reveal that ALT-C is a strong candidate to be exploited in the development of anti-inflammatory and anti-angiogenic therapies in chronic inflammatory processes.

Structurally Robust and Functionally Highly Versatile-C-Type Lectin (-Related) Proteins in Snake Venoms

Snake venoms contain an astounding variety of different proteins. Among them are numerous C-type lectin family members, which are grouped into classical Ca²⁺- and sugar-binding lectins and the non-sugar-binding snake venom C-type lectin-related proteins (SV-CLRPs), also called snaclecs. Both groups share the robust C-type lectin domain (CTLD) fold but differ in a long loop, which either contributes to a sugar-binding site or is expanded into a loop-swapping heterodimerization domain between two CLRP subunits. Most C-type lectin (-related) proteins assemble in ordered supramolecular complexes with a high versatility of subunit numbers and geometric arrays. Similarly versatile is their ability to inhibit or block their target molecules as well as to agonistically stimulate or antagonistically blunt a cellular reaction triggered by their target receptor. By utilizing distinct interaction sites differentially, SV-CLRPs target a plethora of molecules, such as distinct coagulation factors and receptors of platelets and endothelial cells that are involved in hemostasis, thrombus formation, inflammation and hematogenous metastasis. Because of their robust structure and their high affinity towards their clinically relevant targets, SV-CLRPs are and will potentially be valuable prototypes to develop new diagnostic and therapeutic tools in medicine, provided that the molecular mechanisms underlying their versatility are disclosed.

Inflammation, angiogenesis and fibrogenesis are differentially modulated by distinct domains of the snake venom metalloproteinase jararhagin

Jararhagin, a metalloprotease from Bothrops jararaca snake venom, is a toxin containing the metalloproteinase, disintegrin-like and cysteine-rich domains; it causes acute inflammation and damage to vascular tissue. However, the actions of these domains on key components of chronic inflammation have not been determined. Our aim was to investigate the effects of jararhagin (Jar), jararhagin-C (Jar-C) and o-phenantrolin-treated jararhagin (Jar-Phe), on inflammatory response, blood vessel formation and extracellular matrix deposition in the murine sponge model. The polyether-polyurethane sponge matrix was implanted into Balb/c mice and injected daily with Jar (400 ng), Jar-Phe (400 ng), Jar-C (200 ng) or saline (control). Nine days after implantation, the sponge discs were removed and processed. In the Jar-treated implants, some of inflammatory markers (N-acetyl-β-d-glucosaminidase activity, CCL2 and TNF-α) and TGF-β1 levels were higher compared with the control group. In the Jar-C group, the inflammatory markers myeloperoxidase activity and CXCL1 were higher compared with the control. In this group, VEGF levels and collagen deposition were also higher. Jar-Phe treatment was able to inhibit the activity and/or production of MPO, CXCL1, CCL2 and TGF-β. The differential effects of these proteins in modulating the main components of fibrovascular tissue may be exploited in the management fibroproliferative diseases.

Effects of auriculasin on vascular endothelial growth factor (VEGF)-induced angiogenesis via regulation of VEGF receptor 2 signaling pathways in vitro and in vivo

Angiogenesis plays an important role in various pathological conditions such as cancer via excessive delivery of oxygen and nutrients. Recent studies have demonstrated that understanding the molecular basis of natural agents in angiogenesis is critical for the development of promising cancer therapeutics. In this study, auriculasin, an active component from Flemingia philippinensis, was found to exert strong anti-angiogenesis activity. Treatment with auriculasin suppressed proliferation of human umbilical vein endothelial cells (HUVECs) by modulating expression of Bcl-2, Bcl-_XL, and vascular endothelial growth factor (VEGF). Further, auriculasin inhibited VEGF-induced chemotactic migration, invasion, and capillary-like structure formation of endothelial cells. In addition, auriculasin abrogated VEGF-induced vascular network formation around rat aortic rings as well as blocked accumulation of hemoglobin, endothelial cells and VEGF in the Matrigel plug of C57BL/6 mice. The inhibitory effect of auriculasin on angiogenesis was well correlated with inhibition of VEGF receptor 2 (VEGFR2) activation as well as phosphorylation of intracellular downstream protein kinases of VEGFR2 containing Akt, mammalian target of rapamycin (mTOR), phosphoinositide 3-kinase (PI3K), p-38, extracellular signal-related kinase (ERK), and Src. Taken together, this study reports that auriculasin potently inhibits angiogenesis by modulating VEGFR2-related signaling pathways, which further validates its great potential in clinical applications.