Mechanisms of Vascular Damage by Hemorrhagic Snake Venom Metalloproteinases: Tissue Distribution and In Situ Hydrolysis

Abstract

BackgroundEnvenoming by viper snakes constitutes an important public health problem in Brazil and other developing countries. Local hemorrhage is an important symptom of these accidents and is correlated with the action of snake venom metalloproteinases (SVMPs). The degradation of vascular basement membrane has been proposed as a key event for the capillary vessel disruption. However, SVMPs that present similar catalytic activity towards extracellular matrix proteins differ in their hemorrhagic activity, suggesting that other mechanisms might be contributing to the accumulation of SVMPs at the snakebite area allowing capillary disruption.Methodology/Principal FindingsIn this work, we compared the tissue distribution and degradation of extracellular matrix proteins induced by jararhagin (highly hemorrhagic SVMP) and BnP1 (weakly hemorrhagic SVMP) using the mouse skin as experimental model. Jararhagin induced strong hemorrhage accompanied by hydrolysis of collagen fibers in the hypodermis and a marked degradation of type IV collagen at the vascular basement membrane. In contrast, BnP1 induced only a mild hemorrhage and did not disrupt collagen fibers or type IV collagen. Injection of Alexa488-labeled jararhagin revealed fluorescent staining around capillary vessels and co-localization with basement membrane type IV collagen. The same distribution pattern was detected with jararhagin-C (disintegrin-like/cysteine-rich domains of jararhagin). In opposition, BnP1 did not accumulate in the tissues.Conclusions/SignificanceThese results show a particular tissue distribution of hemorrhagic toxins accumulating at the basement membrane. This probably occurs through binding to collagens, which are drastically hydrolyzed at the sites of hemorrhagic lesions. Toxin accumulation near blood vessels explains enhanced catalysis of basement membrane components, resulting in the strong hemorrhagic activity of SVMPs. This is a novel mechanism that underlies the difference between hemorrhagic and non-hemorrhagic SVMPs, improving the understanding of snakebite pathology.

Antibodies against Venom of the Snake Deinagkistrodon acutus

“…The P-III class showed more hemorrhagic and diverse biological activities than P-I and P-II (8,(49)(50)(51). Hemorrhagic P-III SVMPs, which comprise the metalloprotease domain and disintegrin-like (Dis) domain, followed by a cysteine-rich (CR) domain, gather in capillary blood and vessels by binding to the basement membrane through the Dis and CR domains to disrupt the microvascular system very effectively (52). In addition, the noncatalytic Dis and CR domains containing substrate binding sites were considered to confer greater hemorrhagic activity on P-III SVMPs (53).…”

Clinical Toxinology

“…Studies of these toxins have elucidated their actions, including recent work showing that the toxins accumulate at the vascular basement membrane and probably bind to collagens, which are then hydrolyzed, causing hemorrhagic lesions [27].…”

Associação de plasma sanguíneo ao tratamento de envenenamento botrópico em equino: relato de caso

“…A adsorção ocorre nos componentes celulares, por ligação a estes. Dessa maneira, altera a integridade vascular e induz o sangramento local, um dos principais sinais do envenenamento (Baldo et al, 2010). Além desta ação vasculotóxica, segundo Cominetti et al (2003), as alterações hemostáticas também são causadas pela ação coagulante, provavelmente por degradação dos fatores da cascata de coagulação, como o II, V,VIII e X.…”

“…O animal em estudo apresentou sinais clínicos semelhantes aos descritos na literatura. As lesões identificadas são provocadas pelas ações proteolítica, coagulante e hemorrágica do veneno, que possui mais de 20 substâncias, as quais atuam causando inflamação, dano ao epitélio vascular, incoagulabilidade sanguínea e necrose local (Baldo et al, 2010).…”