Effect of iron and carbon monoxide on fibrinogenase-like degradation of plasmatic coagulation by venoms of four Crotalus species

Abstract

Annually, thousands suffer poisonous snake bite, often from defibrinogenating species. Iron and carbon monoxide (CO) improve coagulation kinetics by modulation of fibrinogen as demonstrated in various Agkistrodon species and Crotalus atrox. Thus, we sought to determine whether pretreatment of plasma with iron and CO could attenuate venom-mediated catalysis of fibrinogen obtained from four common Crotalus species with known fibrinogenase activity. Human plasma was pretreated with ferric chloride (0-10 μmol/l) and CO-releasing molecule-2 (0-100 μmol/l) prior to exposure to venom from a Northern Pacific rattlesnake, Arizona black rattlesnake, prairie rattlesnake, or red diamond rattlesnake. The concentration of venom used decreased coagulation function of one or more kinetic parameters by at least 50% of normal values. Coagulation kinetics were determined with thrombelastography.Three snake venoms significantly degraded plasmatic coagulation kinetics, prolonging the onset to clot formation, diminishing velocity of clot growth and decreasing clot strength. However, red diamond rattlesnake venom exposure resulted in mixed coagulation kinetics, significantly decreasing the time to onset of coagulation without decreasing the velocity of clot growth. Iron and CO attenuated these coagulation kinetic changes in a species-specific manner. Further in vitro investigation of other fibrinogenolytic venoms is indicated to determine if iron and CO can attenuate venom compromised coagulation.

Characterization of the Rabbit as an In Vitro and In Vivo Model to Assess the Effects of Fibrinogenolytic Activity of Snake Venom on Coagulation

“…Extensive in vitro investigation of novel therapeutic methods to abrogate the fibrinogenolytic/thrombin-like activity of snake venom metalloproteinases (SVMP) and snake venom serine proteases (SVSP) has been pursued by our laboratory recently [1][2][3][4][5][6][7]. The first method was to modify fibrinogen in human plasma by exposure to iron (Fe) and carbon monoxide (CO), rendering this 'stealth' fibrinogen less recognizable to SVMPs [1][2][3][4]. The second approach was direct, isolated exposure of SVMP and SVSP to CO in vitro, with subsequent loss of associated fibrinogenolytic or thrombin-like activity observed in human plasma [4][5][6][7].…”

Carbon monoxide releasing molecule enhances coagulation and decreases fibrinolysis in canine plasma exposed to Crotalus viridis venom in vitro and in vivo

“…Nielsen et al showed that pre‐incubating normal human plasma with CORM‐2 and ferric chloride (FeCl 3 ) mitigated the deleterious effects of venom from both North American and non‐North American vipers. FeCl 3 modulates the alpha chain of fibrinogen, while CORM‐2 (the CO‐derived therefrom) binds to a fibrinogen‐bound haem group, both changes the conformation of fibrinogen . These reports did not describe the effects of these molecules on venom‐induced hyperfibrinolysis.…”

“…Alteration of the human fibrinogen molecule has been shown to create resistance to venom‐induced hypocoagulability . Nielsen et al showed that pre‐incubating normal human plasma with CORM‐2 and ferric chloride (FeCl 3 ) mitigated the deleterious effects of venom from both North American and non‐North American vipers.…”

“…Rattlesnake envenomation occurs frequently in dogs throughout the United States and often causes coagulopathy. Rattlesnake venom decreases fibrinogen function by abnormally cleaving fibrinogen alpha and beta chains and rendering it poorly functional for polymerization . In general, antivenom lessens coagulopathy induced by crotalid species; however, it is expensive (especially if multiple doses are necessary), time‐sensitive and poorly available, and some formulations have a short half‐life .…”

“…Previous findings of the clot strengthening effects of CO led us to hypothesize that CO may be able to strengthen clot formation in plasma from normal dogs exposed to Prairie rattlesnake ( Crotalus viridis) venom and in plasma from naturally envenomed dogs . To date, CORM‐2 has been shown to mitigate coagulopathy induced by several crotalid venoms in human plasma . Coagulopathy is a common sequel to rattlesnake bites in human beings and canine victims.…”