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Frontiers in Immunology 2021Rattlesnakes are a diverse clade of pit vipers (snake family Viperidae, subfamily Crotalinae) that consists of numerous medically significant species. We used validated...
Rattlesnakes are a diverse clade of pit vipers (snake family Viperidae, subfamily Crotalinae) that consists of numerous medically significant species. We used validated assays measuring venom-induced clotting time and strength of any clots formed in human plasma and fibrinogen to assess the coagulotoxic activity of the four medically relevant Mexican rattlesnake species , and . We report the first evidence of true procoagulant activity by Neotropical rattlesnake venom in . This species presented a strong ontogenetic coagulotoxicity dichotomy: neonates were strongly procoagulant Factor X activation, whereas adults were pseudo-procoagulant in that they converted fibrinogen into weak, unstable fibrin clots that rapidly broke down, thereby likely contributing to net anticoagulation through fibrinogen depletion. The other species did not activate clotting factors or display an ontogenetic dichotomy, but depleted fibrinogen levels by cleaving fibrinogen either in a destructive (non-clotting) manner or a pseudo-procoagulant mechanism. We also assessed the neutralization of these venoms by available antivenom and enzyme-inhibitors to provide knowledge for the design of evidence-based treatment strategies for envenomated patients. One of the most frequently used Mexican antivenoms (Bioclon Antivipmyn®) failed to neutralize the potent procoagulant toxic action of neonate venom, highlighting limitations in snakebite treatment for this species. However, the metalloprotease inhibitor Prinomastat substantially thwarted the procoagulant venom activity, while 2,3-dimercapto-1-propanesulfonic acid (DMPS) was much less effective. These results confirm that venom-induced Factor X activation (a procoagulant action) is driven by metalloproteases, while also suggesting Prinomastat as a more promising potential adjunct treatment than DMPS for this species (with the caveat that studies are necessary to confirm this potential clinical use). Conversely, the serine protease inhibitor 4-(2-aminoethyl)benzenesulfonyl fluoride hydrochloride (AEBSF) inhibited the direct fibrinogen cleaving actions of venom, thereby revealing that the pseudo-procoagulant action is driven by kallikrein-type serine proteases. Thus, this differential ontogenetic variation in coagulotoxicity patterns poses intriguing questions. Our results underscore the need for further research into Mexican rattlesnake venom activity, and also highlights potential limitations of current antivenom treatments.
Topics: Animals; Antivenins; Blood Coagulation; Blood Coagulation Factors; Blood Coagulation Tests; Coagulation Protein Disorders; Crotalid Venoms; Crotalus; Mexico; Neutralization Tests
PubMed: 33815366
DOI: 10.3389/fimmu.2021.612846 -
Scientific Reports Feb 2024Local tissue damage following snakebite envenoming remains a poorly researched area. To develop better strategies to treat snakebites, it is critical to understand the...
Local tissue damage following snakebite envenoming remains a poorly researched area. To develop better strategies to treat snakebites, it is critical to understand the mechanisms through which venom toxins induce envenomation effects including local tissue damage. Here, we demonstrate how the venoms of two medically important Indian snakes (Russell's viper and cobra) affect human skeletal muscle using a cultured human myoblast cell line. The data suggest that both venoms affect the viability of myoblasts. Russell's viper venom reduced the total number of cells, their migration, and the area of focal adhesions. It also suppressed myogenic differentiation and induced muscle atrophy. While cobra venom decreased the viability, it did not largely affect cell migration and focal adhesions. Cobra venom affected the formation of myotubes and induced atrophy. Cobra venom-induced atrophy could not be reversed by small molecule inhibitors such as varespladib (a phospholipase A inhibitor) and prinomastat (a metalloprotease inhibitor), and soluble activin type IIb receptor (a molecule used to promote regeneration of skeletal muscle), although the antivenom (raised against the Indian 'Big Four' snakes) has attenuated the effects. However, all these molecules rescued the myotubes from Russell's viper venom-induced atrophy. This study demonstrates key steps in the muscle regeneration process that are affected by both Indian Russell's viper and cobra venoms and offers insights into the potential causes of clinical features displayed in envenomed victims. Further research is required to investigate the molecular mechanisms of venom-induced myotoxicity under in vivo settings and develop better therapies for snakebite-induced muscle damage.
Topics: Humans; Animals; Naja naja; Daboia; Snake Bites; Viper Venoms; Elapidae; Elapid Venoms; Myoblasts; Atrophy
PubMed: 38326450
DOI: 10.1038/s41598-024-53366-9 -
Osteoarthritis and Cartilage Open Jun 2021Arthropathy is a major clinical problem in patients with hemochromatosis, the most common genetic disorder of iron overload. The pathological features of hemochromatosis...
OBJECTIVE
Arthropathy is a major clinical problem in patients with hemochromatosis, the most common genetic disorder of iron overload. The pathological features of hemochromatosis arthropathy (HA) are heterogeneous and its specific nature remains unknown. One important drawback is the lack of proper models. The aim of the present study was to set up a model to investigate the biological response of cartilage to iron exposure.
DESIGN
Bovine articular cartilage explants were incubated with ferric citrate for up to 9 days. We evaluated chondrocyte viability, iron deposition, and biomarkers of cartilage degradation in the conditioned medium.
RESULTS
Iron accumulated within chondrocytes, which was associated with programmed cell death through chondroptosis. Iron treatment increased the release of sulfated glycosaminoglycans (sGAG), a component of the extracellular matrix, into the medium (p=0.0189). This was dependent on the presence of viable chondrocytes and was associated with increased activity of matrix-degrading metalloproteinases (MMP) (pro/active MMP-9, p=0.0317; pro MMP-2, p=0.0092; active MMP-2, p=0.0288). Co-treatment with the broad MMP/aggrecanase inhibitor prinomastat reduced iron-mediated sGAG release (0.02 μM, p=0.0425; 2 μM, p=0.0014), confirming that iron induces sGAG release via the activation of catabolic enzymes. Notably, iron-treated cartilage continued to release an increased amount of sGAG into the medium for 6 days after termination of the ferric citrate treatment (p=0.0259).
CONCLUSIONS
Iron triggers the early stages of cartilage degeneration. Removal of iron exposure does not prevent further damage to the cartilage, thus providing a possible explanation why HA is not prevented after iron depletion by phlebotomy treatment.
PubMed: 36474980
DOI: 10.1016/j.ocarto.2021.100145