XJ-8, a natural compound isolated from Sanguis draxonis, inhibits platelet function and thrombosis by targeting MAP3K3

Tanshinone I inhibits the functions of T lymphocytes and exerts therapeutic effects on delayed-type hypersensitivity reaction via blocking STATs signaling pathways

Delayed-type hypersensitivity (DTH) reactions are a kind of chronic inflammatory diseases initiated by antigens and antigen-specific T cells. Currently, the therapy of DTH reactions is limited by the poor curative effects and serious adverse reactions of existing agents. In this study, we investigated the regulatory effects of tanshinone Ⅰ, a natural compound isolated from Salvia miltiorrhiza, on the functions of multiple immune cells and its therapeutic effects on DNFB-induced DTH reaction, and then explored its immunosuppressive mechanisms. The results showed that tanshinone Ⅰ at 5-20 μM moderately inhibited the activation of macrophages and dendritic cells, but did not weaken the activation of neutrophils. Tanshinone Ⅰ at 1-4 μM intensively suppressed the activation, proliferation, and differentiation of CD4+ and CD8+ T cells, and slightly affected the functions of B cells. Tanshinone Ⅰ administration markedly alleviated the edema, inflammatory response, and the infiltrations of CD4+ T cells, CD8+ T cells, and CD11b+ cells in ear tissues of mice which were induced DTH reactions by DNFB. Transcriptome analysis revealed that tanshinone Ⅰ strongly inhibited CD4+ T cells to express genes involving in cell proliferation, metabolism, activation, and differentiation. Furthermore, immunoblotting analysis showed that tanshinone Ⅰ selectively inhibited the phosphorylation of STAT3 and STAT5 in CD4+ T cells stimulated by anti-CD3e and anti-CD28 antibodies or IL-2. Collectively, tanshinone Ⅰ can strongly inhibit the functions of T lymphocytes, exert therapeutic effects on DTH reaction by blocking STATs signaling pathways, and has potential to be developed into therapeutic drug for DTH reactions.

Icaritin Sensitizes Thrombin- and TxA2-Induced Platelet Activation and Promotes Hemostasis via Enhancing PLCγ2-PKC Signaling Pathways

BACKGROUND

 Vascular injury results in uncontrollable hemorrhage in hemorrhagic diseases and excessive antithrombotic therapy. Safe and efficient hemostatic agents which can be orally administered are urgently needed. Platelets play indispensable roles in hemostasis, but there is no drug exerting hemostatic effects through enhancing platelet function.

METHODS

 The regulatory effects of icaritin, a natural compound isolated from Herba Epimedii, on the dense granule release, thromboxane A2 (TxA2) synthesis, α-granule release, activation of integrin αIIbβ3, and aggregation of platelets induced by multiple agonists were investigated. The effects of icaritin on tail vein bleeding times of warfarin-treated mice were also evaluated. Furthermore, we investigated the underlying mechanisms by which icaritin exerted its pharmacological effects.

RESULTS

 Icaritin alone did not activate platelets, but significantly potentiated the dense granule release, α-granule release, activation of integrin αIIbβ3, and aggregation of platelets induced by thrombin and U46619. Icaritin also shortened tail vein bleeding times of mice treated with warfarin. In addition, phosphorylated proteome analysis, immunoblotting analysis, and pharmacological research revealed that icaritin sensitized the activation of phospholipase Cγ2 (PLCγ2)-protein kinase C (PKC) signaling pathways, which play important roles in platelet activation.

CONCLUSION

 Icaritin can sensitize platelet activation induced by thrombin and TxA2 through enhancing the activation of PLCγ2-PKC signaling pathways and promote hemostasis, and has potential to be developed into a novel orally deliverable therapeutic agent for hemorrhages.