Study On The Functions And Mechanisms Of Haemaphysalis Longicornis-Derived Anti-Thrombosis Peptide YY-39

Thrombotic disease (TD) is a lethal medical complication with high incidence. It is the leading cause of human death all around the world. During the last few decades, various therapeutic treatment of thromboembolism complication such as anti-platelet, anti-clotting, and other anti-thrombosis agents emerged with the continuous increase of TD incidence. However, more or less side effects are present in each of them. Therefore, the pursuit of high quality thrombolytic agent will never be stopped.Ticks as vectors are the most important ecto-parasites of domestic animals and are the second-most important vector next to mosquitoes among arthropods that transmit infectious diseases in human. Haemaphysalis longicornis is a main kind of hard ticks in China, which is widely distributed both in the north and south China. Because of their roles in transmission of a wide range of pathogens, they had been intensively studied, but we almost knew nothing about the salivary gland bacterial endosymbionts.The strain of TSG4 was isolated from Haemaphysalis longicornis salivary gland by our lab before. In this study, we purified a peptide acting as platelet aggregation inhibitor from its fermented liquid, nominated it as YY-39, composed of 39 amino acid. In order to investigate the structure-function relationship of YY-39, which were then synthesized by solid-phase chemistry method. Reverse-phase high performance liquid chromatography (RP-HPLC) and matrix assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/TOF MS) were used to monitor the oxidative refolding process of synthetic linear peptides to find the optimal renaturation conditions.We studied the anti-thrombosis activity in vivo, such as bleeding time which assessed by a tail transection method, carrageenan-induced mouse-tail thrombosis model, and confirmed that YY-39 including the RGD domain is a novel receptor antagonist of platelet glycoprotein Ⅱb/Ⅲa (αⅡbβ3) and displays potent antithrombotic properties. In addition, we studied the bleeding side effect of YY-39 and found that YY-39 did not cause bleeding under the concentration of 65 nmol/kg. At last, we study the anti-tumor activity in vitro, results showed that the proliferation of tumor cells was signally inhibited by the YY-39 with a dose compliance. This progress relieve the restriction of the resources poverty. More important, our research provide a substantial foundation to the excavation for anti-thombosis leading molecular, the industrial exploitation and the clinical application of the traditional Eastern medicine insect material.