[Effect of protein C activator from Agkistrodon acutus venom on early adaptive immune response of septic rats].

OBJECTIVE: To investigate the effect of protein C activator (PCA) from Agkistrodon acutus venom (AAV) in modulating early adaptive immune response of septic rats. OBJECTIVE: Rat models of sepsis were established by intraperitoneal injection of lipopolysaccharide (LPS; 10 mg/kg) in 36 SD rats, which were divided into 6 groups (n=6) for sample collection at 4, 6, 8, 12, 16 and 24 h after LPS injection, with 6 rats injected with saline as the control group. Another 36 rats were divided into two groups, and 30 min after LPS injection, the rats were treated with SEW2871 (a sphingosine-1-phosphate receptor 1 agonist; 0.5 mg/kg) or PCA group (0.1 mg/kg), and each group was divided into 3 groups (n=6) for sample collection at 6, 12 and 24 h after LPS injection. Plasma IL-4, S1P, IL-12 and IFN-γ levels of the rats were detected using ELISA, and the expressions of S1PR1 and CD103 in the mesenteric lymph nodes were detected with immunofluorescence assay. OBJECTIVE: The plasma levels of S1P, IL-12, IL-4 and IFN-γ (P < 0.05) and the expressions of S1PR1 and CD103 in the mesenteric lymph nodes (P < 0.05) all increased significantly in the rats 24 h after LPS injection; IFN-γ/IL-4 ratio increased progressively within 6 h after LPS injection and then subsided gradually. Compared with those in the corresponding sepsis model subgroups, the levels of S1P, IL-12 and IFN-γ increased while IL- 4 level decreased significantly (P < 0.05), and the expression of S1PR1 and CD103 were reduced significantly (P < 0.05) in SEW2871-treated rats; both the plasma level of IL-4 and the expression of S1PR1 in the mesenteric lymph nodes increased significantly in PCA-treated rats (P < 0.05). OBJECTIVE: PCA can regulate the balance of inflammation and immune response in the early stage of sepsis in rats possibly through the S1P-S1PR1 pathway.