HomeCirculationVol. 142, No. 24Response by Xu et al to Letter Regarding Article, “Branched-Chain Amino Acid Catabolism Promotes Thrombosis Risk by Enhancing Tropomodulin-3 Propionylation in Platelets” Free AccessLetterPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyRedditDiggEmail Jump toFree AccessLetterPDF/EPUBResponse by Xu et al to Letter Regarding Article, “Branched-Chain Amino Acid Catabolism Promotes Thrombosis Risk by Enhancing Tropomodulin-3 Propionylation in Platelets” Yanyan Xu, PhD, Haojie Jiang, PhD and Junling Liu, PhD Yanyan XuYanyan Xu Department of Biochemistry and Molecular Cell Biology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, China (Y.X., H.J., J.L.). Search for more papers by this author , Haojie JiangHaojie Jiang Department of Biochemistry and Molecular Cell Biology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, China (Y.X., H.J., J.L.). Search for more papers by this author and Junling LiuJunling Liu Department of Biochemistry and Molecular Cell Biology, Key Laboratory of Cell Differentiation and Apoptosis of Chinese Ministry of Education, Shanghai Jiao Tong University School of Medicine, China (Y.X., H.J., J.L.). The Cyrus Tang Hematology Center, Collaborative Innovation Center of Hematology, Soochow University, Suzhou, China (J.L.). Search for more papers by this author Originally published14 Dec 2020https://doi.org/10.1161/CIRCULATIONAHA.120.051367Circulation. 2020;142:e452–e453In Response:We thank Dr Liu and colleagues for their interest in our article, “Branched-Chain Amino Acid Catabolism Promotes Thrombosis Risk by Enhancing Tropomodulin-3 Propionylation in Platelets.”1We fully agree with Dr Liu that further exploration of the functions of leucine and mammalian target of rapamycin pathway will strengthen the understanding of the mechanism of branched-chain amino acid (BCAA)–induced platelet activation. In our previous study, we studied the individual functions of valine, isoleucine, leucine, and their catabolites on platelet activation. We found that valine/α-ketoisovaleric acid has the most significant promoting effect on platelet activation among BCAAs and branched-chain α-keto acids. Propionyl coenzyme A, as the end product of valine and isoleucine metabolism, promotes platelet aggregation and the TMOD3 (tropomodulin 3) propionylation. Leucine catabolism eventually leads to the formation of acetoacetyl coenzyme A and acetyl coenzyme A, but not propionyl coenzyme A. We found that leucine and its metabolite α-ketoisocaproic acid enhance agonist-induced platelet aggregation and P-selectin exposure. These suggested that there must be some other mechanisms between BCAAs and thrombosis formation. It has been reported that leucine participates in the mammalian target of rapamycin signaling pathway in T cells, macrophages, and other cells.2 It is necessary to further investigate the relationship between leucine and mammalian target of rapamycin in the process of platelet activation and thrombosis.We agree with Dr Liu that the age, medication, and diet of patients with type 2 diabetes mellitus should be taken into consideration to demonstrate the relationship between BCAA levels and platelet activation. In our study, the average age of inpatients with type 2 diabetes mellitus was 57.5±3.7 years and all patients had taken medication to control blood glucose level. Apparently, the number of patients in our study was not enough to perform the analysis of the correlation between the age, medication, diet, and the levels of BCAAs and platelet activation in patients. Larger scaled experiments are required to resolve this issue.As Dr Liu pointed out, BCAAs and branched-chain α-keto acids are supplied to patients who have chronic renal failure with other essential amino acids and their ketoanalogues to decrease protein intake as much as possible and maintain protein balance, which may increase the risk of thrombosis.3,4 Our unpublished data showed that P2Y12 inhibitor ticagrelor and thromboxane A2 production blocker aspirin significantly inhibited the enhancing effects of BCAAs on the aggregation of platelets in response to different agonists in vitro, which suggested that utilization of current antiplatelet drugs might reduce the risk of thrombosis in the therapy of patients with chronic renal failure. However, further basic and clinical studies must be performed before applying the findings to the supplement of BCAAs in patients.DisclosuresNone.
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