Poor Regenerative Outcome after Skeletal Muscle Necrosis Induced by Bothrops asper Venom: Alterations in Microvasculature and Nerves

Abstract

BackgroundViperid snakebite envenoming is characterized by prominent local tissue damage, including muscle necrosis. A frequent outcome of such local pathology is deficient skeletal muscle regeneration, which causes muscle dysfunction, muscle loss and fibrosis, thus provoking permanent sequelae that greatly affect the quality of life of patients. The causes of such poor regenerative outcome of skeletal muscle after viperid snakebites are not fully understood.Methodology/Principal FindingsA murine model of muscle necrosis and regeneration was adapted to study the effects of the venom and isolated toxins of Bothrops asper, the medically most important snake in Central America. Gastrocnemius muscle was injected with either B. asper venom, a myotoxic phospholipase A2 (Mtx), a hemorrhagic metalloproteinase (SVMP), or saline solution. At various time intervals, during one month, tissue samples were collected and analyzed by histology, and by immunocytochemical and immunohistochemical techniques aimed at detecting muscle fibers, collagen, endothelial cells, myoblasts, myotubes, macrophages, TUNEL-positive nuclei, and axons. A successful regenerative response was observed in muscle injected with Mtx, which induces myonecrosis but does not affect the microvasculature. In contrast, poor regeneration, with fibrosis and atrophic fibers, occurred when muscle was injected with venom or SVMP, both of which provoke necrosis, microvascular damage leading to hemorrhage, and poor axonal regeneration.Conclusions/SignificanceThe deficient skeletal muscle regeneration after injection of B. asper venom is likely to depend on the widespread damage to the microvasculature, which affects the removal of necrotic debris by phagocytes, and the provision of nutrients and oxygen required for regeneration. In addition, deficient axonal regeneration is likely to contribute to the poor regenerative outcome in this model.

Chronic Musculoskeletal Disabilities following Snake Envenoming in Sri Lanka: A Population-Based Study

“…However, the dearth of studies on long term musculoskeletal sequelae, particularly from regions such as Latin America [23] and Africa [12, 14] plagued with snake species that cause severe local tissue damage, precludes confirmation of this postulation. Nonetheless, a need for therapies to counteract local venom effects has been recognised and used against some species [24].…”

Melatonin alleviates Echis carinatus venom‐induced toxicities by modulating inflammatory mediators and oxidative stress

“…Among subjects with viper bites, more than 75% of the victims suffer from severe local effects including hemorrhage and myonecrosis . Information on the viper venom‐induced local effects from past decade has demonstrated the direct involvement of SVMPs and SVHYs (snake venom hyaluronidases), identifying them as ‘spreading factors’ .…”

“…Besides the inability of antivenoms to block local effects and the fact melatonin is already in clinical applications as an approved drug, its use in viper bite management is of high interest and demanding. Among subjects with viper bites, more than 75% of the victims suffer from severe local effects including hemorrhage and myonecrosis [50]. Information on the viper venom-induced local effects from past decade has demonstrated the direct involvement of SVMPs and SVHYs (snake venom hyaluronidases), identifying them as 'spreading factors' [51][52][53].…”

Biochemical and functional studies of ColTx-I, a new myotoxic phospholipase A2 isolated from Crotalus oreganus lutosus (Great Basin rattlesnake) snake venom

“…Myotoxic PLA 2 s are involved in local and systemic skeletal muscle degeneration, a common pathophysiological event in viperid snakebite envenomation (Gutierrez and Ownby, 2003;Hernandez et al, 2011). These events are accompanied by an acute inflammatory reaction associated with swelling, pain and the recruitment of macrophages and polymorphonuclear leukocytes (Chacur et al, 2003;Gutierrez et al, 2009;Mamede et al, 2013).…”

“…Activated leukocytes secrete a wide range of chemical mediators such as IL-1, IL-6 and IL-8, which along with the biological effects induced by the toxin, may contribute to the evolution of local myotoxicity and regeneration Voronov et al, 1999). Local myonecrosis is a difficult medical challenge owing to its rapid development and poor tissue regeneration characterized by dysfunction and tissue loss, which have negative social and psychological consequences (Hernandez et al, 2011;Tonello et al, 2012). The effects triggered by PLA 2 s occur upon interaction with lipids or proteins, altering the plasma membrane integrity by catalytically dependent or independent mechanisms that consequently mediate a number of associated events, such as: calcium influx, depolarization, loss of ionic gradients and efflux of cytosolic molecules (Kini, 2003;Montecucco et al, 2008).…”