The Effect of Tanshinone-IIa on IL-1β Induced-Thrombocytosis in an Immune Vasculitis Model

Inflammation cytokines may be involved in the pathogenesis of thrombocytosis with vasculitis. Our previous study showed that inflammation cytokine IL-1β plays an important role on in-vitro megakaryopoiesis ( Yang M et al, Br J Haematol 2000 ). The role of IL-1β and Tanshinone IIA (TIIA) (Isolated from Danshen, Radix Salviae Miltiorrhiza Bge ) on platelets and megakaryocytes (MKs) in immune vasculitis model was investigated in this study. Rabbit model with immune vasculitis was established by injection (iv) of BSA. After treatment with BSA for 7 days, the platelet count, platelet aggregation and the expression of AnnexinⅤ were significantly increased in this vasculitis model group compared with normal control group (n=7). IL-1β levels was also significantly higher in vasculitis model. There were positive correlations between platelet count and IL-1β levels (R=0.65), platelet aggregation and IL-1β levels (R=0.60). Treatment with TIIA (5 mg/kg/day, iv) and aspirin significantly decreased all these parameters. MKs and CFU-MK number were also significantly increased in vasculitis group as compared to normal group. Treatment with TIIA and aspirin significantly reduced the number of MKs and CFU-MK in this model. Study further demonstrated that IL-1β alone or in combination with TPO induced in-vitro CFU-MK formation. The mRNA of of IL-1 type I and type II receptors (IL-1 RI and RII) were detected in cultured MK (CD61+ CD41+) cells. The expression of IL-1 RI and RII was also confirmed by immunofluorescence staining in bone marrow MKs. Moreover, the IL-1R bloker can reduced IL-1β induced megakaryopoiesis. TIIA on in-vitro megakaryopoiesis was also investigated. TIIA at 10-30 ug/ml significantly inhibited CFU-MK formation. TIIA also induced the apoptosis of MKs in a dose dependent manner by Anexin V assay. Caspase 3 assay showed the activation of Caspase 3 increased from 5% to 16%. Using JC-1 assay found that the depolarized cells increased from 9% to 17% suggesting the involvement of intrinsic apoptotic pathway. IL-1β may play an important role in the thrombocytosis of immune vasculitis by inducing megakaryopoiesis. TIIA has anti-platelet effect in this model which may be mediated via inhibiting IL-1β induced-megakaryopoiesis. Disclosures No relevant conflicts of interest to declare.