Arterial Platelet Adhesion in Atherosclerosis-Prone Arteries of Obese, Insulin-Resistant Nonhuman Primates.

Background Platelet-endothelial interactions are thought to contribute to early atherogenesis. These interactions are potentiated by oxidative stress. We used in vivo molecular imaging to test the hypothesis that platelet-endothelial interactions occur at early stages of plaque development in obese, insulin-resistant nonhuman primates, and are suppressed by NADPH-oxidase-2 inhibition. Methods and Results Six adult rhesus macaques fed a Western-style diet for a median of 4.0 years were studied at baseline and after 8 weeks of therapy with the NADPH-oxidase-2-inhibitor apocynin (50 mg/kg per day). Six lean control animals were also studied. Measurements included intravenous glucose tolerance test, body composition by dual-energy X-ray absorptiometry, carotid intimal medial thickness, carotid artery contrast ultrasound molecular imaging for platelet GPIbα (glycoprotein- Ibα) and vascular cell adhesion molecule-1, and blood oxidative markers on mass spectrometry. Compared with lean controls, animals on a Western-style diet were obese (median body mass: 16.0 versus 8.7 kg, P=0.003; median truncal fat: 49% versus 20%, P=0.002), were insulin resistant (4-fold higher insulin-glucose area under the curve on intravenous glucose tolerance test, P=0.002), had 40% larger carotid intimal medial thickness (P=0.004), and exhibited oxidative signatures on proteomics. In obese but not lean animals, signal enhancement on molecular imaging was significantly elevated for GPIbα and vascular cell adhesion molecule-1. The signal correlated modestly with intimal medial thickness but not with the degree of insulin resistance. Apocynin significantly (P<0.01) reduced median signal for GPIbα by >80% and vascular cell adhesion molecule-1 signal by 75%, but did not affect intimal medial thickness, body mass, or intravenous glucose tolerance test results. Conclusion In nonhuman primates, diet-induced obesity and insulin resistance leads to platelet-endothelial adhesion at early atherosclerotic lesion sites, which is associated with the expression of pro-inflammatory adhesion molecules. These responses appear to be mediated, in part, through oxidative pathways.

Plasma proteomic profile associated with platelet dysfunction after trauma.

BACKGROUND: Coagulopathic bleeding is a major cause of mortality after trauma, and platelet dysfunction contributes to this problem. The causes of platelet dysfunction are relatively unknown, but a great deal can be learned from the plasma environment about the possible pathways involved. OBJECTIVE: Describe the changes in plasma proteomic profile associated with platelet dysfunction after trauma. METHODS: Citrated blood was collected from severely injured trauma patients at the time of their arrival to the Emergency Department. Samples were collected from 110 patients, and a subset of twenty-four patients was identified by a preserved (n = 12) or severely impaired (n = 12) platelet aggregation response to five different agonists. Untargeted proteomics was performed by nanoflow liquid chromatography tandem mass spectrometry. Protein abundance levels for each patient were normalized to total protein concentration to control for hemodilution by crystalloid fluid infusion prior to blood draw. RESULTS: Patients with platelet dysfunction were more severely injured but otherwise demographically similar to those with retained platelet function. Of 232 proteins detected, twelve were significantly different between groups. These proteins fall into several broad categories related to platelet function, including microvascular obstruction with platelet activation, immune activation, and protease activation. CONCLUSIONS: This observational study provides a description of the change in proteomic profile associated with platelet dysfunction after trauma and identifies twelve proteins with the most profound changes. The pathways involving these proteins are salient targets for immediate investigation to better understand platelet dysfunction after trauma and identify targets for intervention.

Cysteine Disulfides (Cys-ss-X) as Sensitive Plasma Biomarkers of Oxidative Stress.

We developed a high-throughput mass spectrometry-based method to simultaneously quantify numerous small-molecule thiols and disulfides in blood plasma. Application of this assay to analyze plasma from patients with known oxidative stress (sickle cell disease and sepsis) and from a patient with sickle cell disease treated with the antioxidant N-acetylcysteine suggests that cysteine disulfides, in particular protein-bound cysteine, serve as sensitive plasma biomarkers for the extent of oxidative stress and effectiveness of antioxidant treatment.