Abstract 13827: The Effect of Tanshinone IIA on Megakaryopoiesis in Immune Vasculitis

Abstract

Introduction and Objective: Tanshinone IIA is an active component of Danshen (Radix Salviae Miltiorrhiza Bge), which has been used to treat hypercoagulation-related diseases for centuries. However, its role in megakaryopoiesis remains unclear. Therefore, the present study aimed to examine the effect of Tanshinone IIA on megakaryocytes and platelets in immune vasculitis, and to identify the underlying mechanism(s). Methods: Albino rabbits, aged 3-4 weeks, were used in the present study. Immune vasculitis was established by intravenous injection of BSA (2.5 ml/kg). Tanshinone IIA (5 mg/kg/d) was given through intravenous injection as well. Blood sample was collected from the ear vein and bone marrow was harvested from the femur. Megakaryocytes and CFU-MK were counted with Wright’s and acetylcholine esterase staining, respectively. The coagulation activity and IL-1β level were determined by ELISA. Megakaryocytic cell line CHRF was used to examine the effect of Tanshinone IIA (1-30 μg/mL) on apoptosis; the assay was performed with Annexin V/PI, Caspase 3 and JC-1 using flow cytometry. Results: In rabbits with immune vasculitis, the platelet count, platelet aggregation and prothrombin fragment were significantly increased when compared to their counterparts. Megakaryocytes and CFU-MK were also significantly increased in immune vasculitis. In addition, the level of IL-1β was significantly higher in rabbits with immune vasculitis, which was positively correlated with platelet count and platelet aggregation. Tanshinone IIA (5 mg/kg/d, 7d) significantly reduced the number of megakaryocytes, CFU-MK and platelets, and decreased the coagulation activity. It also significantly lowered the IL-1β level. In megakaryocytic cell line CHRF, Tanshinone IIA (1-30 μg/mL) induced dose-dependent apoptosis. Conclusion: The present study shows that not only platelets, but also megakaryocytes are involved in the pathogenesis of immune vasculitis. IL-1β contributes to the thrombocytosis by inducing megakaryopoiesis. Tanshinone IIA exerts anti-platelet, anti-inflammation and anti-megakaryocyte effects in immune vasculitis; the underlying mechanism may be related to its inhibitory effect on IL-1β and the proapoptotic effect on megakaryocytes.