Mitochondrial oxidants promote platelet activation and thrombotic susceptibility in prediabetes
Azaj Ahmed, Pooja Yadav, Melissa Jensen, Katharine Geasland, Jagadish Swamy, Douglas R. Spitz, E. Dale Abel, Diana Jalal, Sanjana Dayal
Azaj Ahmed, Pooja Yadav, Melissa Jensen, Katharine Geasland, Jagadish Swamy, Douglas R. Spitz, E. Dale Abel, Diana Jalal, Sanjana Dayal
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Research Article Hematology Vascular biology

Mitochondrial oxidants promote platelet activation and thrombotic susceptibility in prediabetes

Abstract

Recent studies suggest prediabetes is an independent risk factor for cardiovascular thrombotic events. However, the mechanisms that may promote platelet activation and thrombosis in prediabetes remain elusive. To determine mechanisms linking prediabetes and thrombosis as a function of age, we recruited military veterans with prediabetes and veterans who were normoglycemic, in young and middle-age groups. Compared with normoglycemic participants, platelets from those with prediabetes exhibited increased activation, mitochondrial oxidant load, mitochondrial membrane hyperpolarization, and greater thrombus formation ex vivo regardless of age. Preincubation of platelets with mitochondria-targeted antioxidants, such as SOD mimetic or mitoquinol (MitoQ), rescued this prothrombotic phenotype. These phenotypes were recapitulated in C57BL6/J mice exhibiting early onset of glucose intolerance when fed a high-fat (HF) diet for 2 weeks. Treatment of HF-fed mice with a SOD mimetic or MitoQ, or genetic overexpression of catalase within mitochondria, not only lowered mitochondrial oxidants, hyperpolarization, Ca2+ levels, and platelet activation but also protected against increased potential for carotid and pulmonary thrombosis. We also observed a bidirectional regulation of platelet activation by Ca2+ and mitochondrial oxidants. These findings support the idea that mitochondrial oxidant–dependent platelet activation induces a prothrombotic state in clinical prediabetes and preclinical models of short-term glucose intolerance and can be reversed by mitochondria-targeted antioxidants.

Authors

Azaj Ahmed, Pooja Yadav, Melissa Jensen, Katharine Geasland, Jagadish Swamy, Douglas R. Spitz, E. Dale Abel, Diana Jalal, Sanjana Dayal

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Figure 8

mCAT-Tg mice are protected from excessive accumulation of platelet lipid peroxides, mitochondrial membrane hyperpolarization, and increased platelet Ca2+ after short-term HF diet feeding.

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mCAT-Tg mice are protected from excessive accumulation of platelet lipid...
Washed platelets were prepared 2 weeks after mice were fed chow or an HF diet, and lipid peroxides were quantified after activation with (A) 0.05 U/mL thrombin or (B) 0.05 U/mL thrombin and 50 ng/mL convulxin, then analyzed via flow cytometry. (C) TMRM fluorescence was measured in washed platelets. (D) Representative tracings of Ca2+ flux measured with Fluo-4 dye at baseline for up to 60 seconds and after 0.05 U/mL thrombin for another 120 seconds. The red arrow indicates the addition of thrombin. Quantification for D is shown (E) at baseline and (F) with thrombin activation. Data for A–C, E, and F are presented as mean ± SEM and analyzed using 2-way ANOVA with Tukey’s test for multiple-group comparisons (n = 5–7 per group). *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001.