Abstract: BACKGROUND: While antivenom has provided hope for treating snakebites, it is not always effective for local tissue damage caused by venomous snakes. Additionally, antivenom has several limitations, including the risk of hypersensitivity, immune reactions like “serum sickness,” and accessibility issues in some regions. Consequently, there is an urgent need to explore complementary or alternative therapies and therapeutic targets for snakebites in clinical settings. 
OBJECTIVE: To observe the effect of the 717 Jiedu Decoction on the expression of extracellular matrix proteins and matrix metalloproteinases/tissue inhibitors of metalloproteinases in the local tissues of rats bitten by Agkistrodon halys.
METHODS: SD rats were randomly divided into a control group, a model group, an anti-viper venom serum group, and 717 Jiedu Decoction low-, medium- and high-dose groups. Except for the control group, all other groups received an injection of 1.25 mL/kg of viper venom into the gastrocnemius muscle of the left hind limb to create a model. The 717 Jiedu Decoction low-, medium- and high-dose groups were administered a preventive oral gavage of 1.98, 3.96, and 7.92 g/kg daily for seven consecutive days prior to the viper venom injection. The anti-viper venom serum group received a tail vein injection of 0.6 mL of antivenom serum two hours after the venom injection. Twenty-four hours post-injection, the pathological changes in the gastrocnemius muscle were observed using hematoxylin-eosin staining. The expression levels of matrix metalloproteinase-2, matrix metalloproteinase-9, tissue inhibitor of metalloproteinase-1, and tissue inhibitor of metalloproteinase-2 proteins, as well as their mRNA in serum and gastrocnemius muscle, were evaluated using ELISA and qPCR. The expression levels of type I collagen, type IV collagen, fibronectin, laminin, α-smooth muscle actin, transforming growth factor-β1, CD31, and vascular endothelial growth factor in the gastrocnemius muscle were analyzed by immunohistochemistry.
RESULTS AND CONCLUSION: (1) Compared to the control group, the model group displayed significant local inflammatory cell infiltration, hemorrhage, muscle structure disruption, and myocyte degeneration and necrosis. The protein and mRNA levels of matrix metalloproteinase-2, matrix metalloproteinase-9, and tissue inhibitor of metalloproteinase-1 in serum and gastrocnemius muscle were elevated (P < 0.05 or P < 0.01), while the mRNA expression of tissue inhibitor of metalloproteinase-2 was reduced (P < 0.01). The protein levels of type I collagen and type IV collagen in the gastrocnemius muscle were significantly decreased (P < 0.01), whereas the protein levels of laminin, vascular endothelial growth factor, and CD31 were increased (P < 0.05 or P < 0.01); however, there were no significant changes in the protein levels of fibronectin, α-smooth muscle actin, and transforming growth factor-β1 (P > 0.05). (2) In contrast to the model group, the 717 Jiedu Decoction low-, medium- and high-dose groups and the anti-viper venom serum group demonstrated alleviated myocyte damage, with improved reduction in inflammatory cell infiltration and hemorrhage. The levels of matrix metalloproteinase-2, matrix metalloproteinase-9, and tissue inhibitor of metalloproteinase-1 in serum and gastrocnemius muscle were significantly reduced (P < 0.05 or P < 0.01). In the high-dose 717 Jiedu Decoction group, the protein level of tissue inhibitor of metalloproteinase-2 was upregulated (P < 0.05). Type I collagen, type IV collagen, laminin, α-smooth muscle actin, and transforming growth factor B1 protein expression were elevated (P < 0.05 or P < 0.01), and there was a dose-effect relationship; vascular endothelial growth factor expression was decreased (P < 0.05 or P < 0.01), there was no significant difference in the expression of fibronectin (P > 0.05); the expression of CD31 protein was elevated in the 717 Jiedu Decoction low-dose group (P < 0.01). The results showed that 717 Jiedu Decoction could promote the production of α-smooth muscle actin and  transforming growth factor β1 by regulating the expression of matrix metalloproteinase 2, matrix metalloproteinase 9 with tissue metalloproteinase inhibitory factor 1, and tissue metalloproteinase inhibitory factor 2, so as to make the synthesis of extracellular matrix greater than the degradation, maintain the extracellular matrix homeostasis, and then promote the repair of local tissue damage in pit viper bites.

中国组织工程研究杂志出版内容重点：组织构建；骨细胞；软骨细胞；细胞培养；成纤维细胞；血管内皮细胞；骨质疏松；组织工程

Key words: Agkistrodon halys bite, 717 Jiedu Decoction, extracellular matrix, gastrocnemius muscle, matrix metalloproteinase, α-smooth muscle actin, transforming growth factor β1, engineered tissue construction