title: Novel strategies to treat snake venom induced muscle damage
Creators: name: Sonavane, Medha
Publisher: name: University of Reading
Year: 2024

description: Snakebite envenoming is a propriety neglected tropical disease that annually claims a 
life of around 150,000 and is responsible for 500,000 disabilities. Skeletal muscle damage is 
a primary factor for snake venom-induced permanent disabilities. The only treatment available 
for snakebite envenoming is anti-venoms produced against venomous snake species. These 
anti-venoms are raised against the geographical venom variant and effectively treat the 
systemic effects of envenoming. However, they fail to treat local tissue damage. Most research 
in the snake venom field is focused on improving anti-venom understanding of venom 
chemistry and physiology. Studies on local effects, pathologies, and treatment of local tissue 
damage are limited. This thesis investigates skeletal muscle pathologies inflicted by snake 
venom, especially snake venom metalloprotease-rich viper venoms. The viper venoms and 
some species of elapids can cause local tissue damage and tissue necrosis. These venoms 
are rich in snake venom metalloproteases (SVMP), three-finger toxins (3FTxs), and 
phospholipase A2, which can induce local damaging effects on the skeletal muscle of the bite 
victim. The elapid venom-mediated damage is often self-resolved; however, in the case of 
viper envenoming, the muscle damage is often permanent. Here, we aim to narrow down 
niche areas in skeletal muscle regeneration affected by viper envenomation. We can use 
innovative methods to target and eliminate the hindrance in the normal regeneration of skeletal 
muscle damage. The factors contributing to impaired muscle regeneration in the case of SBE 
are: 1. The venom proteins are present in the muscle tissue and cause persistent damage. 2. 
The impaired muscle regeneration often results in fibrotic/scar tissue formation that hampers 
muscle regeneration. 3. The snake venom toxins, especially SVMPs, can affect the function 
of muscle stem cells and alter the immune response post-muscle injury, which then 
dysregulated the muscle regeneration process. We selected different approaches to target 
each problem area. We used small molecular inhibitors marimastat and varespladib specific 
for SVMPs and PLA2s to inhibit the initial trigger of active venom proteins. These inhibitor 
molecules improved muscle regeneration, reduced venom pathological effects and restored 
immune response balance. Secondly, we tested the effect of a known anti-fibrotic molecule 
soluble activin receptor IIB to minimise muscle fibrosis, which improved muscle regeneration 
and reduced fibrosis with persistent dosing. Lastly, we have used stem cell-derived condition 
media to boost the innate regeneration mechanism and restore the dysregulation of the 
immune response. The presence of secretome was found effective in enhancing myoblast 
proliferation, differentiation and maturation of muscle cells. All the individual approaches 
achieved effective muscle regeneration. However, there is a possibility of gaining more 
benefits from the combination of these molecules. The Circulatory system also plays a vital 
role in wound healing and regeneration. Hence, we studied the effects of P-III metalloprotease 
from Crotalus atrox (CAMP) venom and a cardiotoxin -I (CTX) from Naja pallida concerning 
intramuscular bleeding and microthrombus formation in the tissue. CAMP affected αIIbβ3 
integrin-mediated thrombus formation, whereas CTX exhibited effects on extrinsic and intrinsic 
clotting pathways. All the approaches tested and validated in this thesis target specific areas 
of muscle regeneration. The small molecule inhibitors target particular proteins in the whole 
venom, soluble activin receptor IIB, target the specific pathological outcome and condition 
media targeted modulation of immune response and muscle stem cells. Hence, these 
treatment molecules may have global application and potential to tackle the crucial 
pathological outcome of envenoming: SBE-induced muscle damage.