Abstract: Objective: To study the protective effect of Lyophyllum ulmarium fibrinolytic enzyme (LUFE) on intimal injury during arterial thrombosis in rats. Methods: Fifty SD rats were randomly divided into five groups: sham operation, model, aspirin, and low- and high-dose LUFE. Before the model establishment, the rats in the aspirin and LUFE groups were administrated with 10 mg/kg mb of aspirin, and 100 and 400 mg/kg mb of LUFE, respectively, by gavage for seven consecutive days. On the following day, the rats in all groups except the sham operation group were administered with ferric chloride to induce carotid artery thrombosis. The morphological changes of carotid artery were observed by HE staining. The serum levels of C-reactive protein (CRP), interleukin (IL)-6, IL-8, monocyte chemoattractant protein-1 (MCP-1), intercellular cell adhesion molecule-1 (ICAM-1), and platelet endothelial cell adhesion molecule-1 (PECAM-1) were detected by an enzyme-linked immunosorbent assay. The level of platelet-leukocyte aggregates (PLA) was detected by flow cytometry. The adhesion of platelets to solidified collagen was observed in vitro after LUFE intervention. The level of Ca2+ in platelets stimulated by collagen was detected by flow cytometry. The phosphorylation levels of platelet linker for activation of T cells (LAT) and phospholipase Cγ (PLCγ) were detected by Western blot. Results: LUFE intervention significantly reduced vascular intimal injury, lowered the levels of serum CPR, IL-6, IL-8, MCP-1, ICAM-1 and PECAM-1 in different degrees, and decreased the level of PLA. LUFE reduced in vitro platelet adhesion to collagen, decreased platelet Ca2+ level, and down-regulated the phosphorylation of platelet LAT and PLCγ proteins. Conclusion: LUFE inhibits vascular inflammation during thrombosis, which may be related to the protective effect on vascular endothelial cells and the antiplatelet effect of LUFE.

Key words: Lyophyllum ulmarium; fibrinolytic enzyme; thrombus; inflammation; platelets