Thioredoxin Inhibitors Attenuate Platelet Function and Thrombus Formation

Thioredoxin (Trx) is definitely an oxidoreductase significant physiological function. Imbalances within the NADPH/thioredoxin reductase/thioredoxin system are connected with numerous pathologies, particularly cancer, and numerous numerous studies for thioredoxin and thioredoxin reductase inhibitors happen to be transported out or are going ahead. Because of the emerging role and need for oxidoreductases for haemostasis and also the current curiosity about developing inhibitors for clinical use, we thought it pertinent to evaluate whether inhibition from the NADPH/thioredoxin reductase/thioredoxin system affects platelet function and thrombosis. We used small molecule inhibitors of Trx (PMX 464 and PX-12) to find out whether Trx activity influences platelet function, plus an impartial proteomics method of identify potential Trx substrates at first glance of platelets that may lead to platelet reactivity and performance. Using LC-MS/MS we discovered that PMX 464 and PX-12 affected the oxidation condition of thiols in many cell surface proteins. Key surface receptors for platelet adhesion and activation were affected, such as the bovine collagen receptor GPVI and also the von Willebrand factor receptor, GPIb. To experimentally validate these bits of information we assessed platelet function in the existence of PMX 464, PX-12, and rutin (a selective inhibitor from the related protein disulphide isomerase). In complete agreement using the proteomics data, small molecule inhibitors of thioredoxin selectively inhibited GPVI-mediated platelet activation, and attenuated ristocetin-caused GPIb-vWF-mediated platelet agglutination, thus validating the findings from the proteomics study. These data reveal a singular role for thioredoxin in controlling platelet reactivity via proteins needed for early platelet responses at sites of vessel injuries (GPVI and GPIb). The work also highlights a possible chance for repurposing of PMX 464 and PX-12 as antiplatelet PX-12 agents.