Pilot Study of Mitochondrial Biology in Human Platelets

Type II diabetes mellitus is rapidly becoming a global pandemic with a deleterious impact on cardiovascular morbidity and mortality. Understanding its pathophysiology is important for the development of future therapeutic interventions. Emerging evidence suggests interplay between mitochondrial dysfunction and the development of insulin resistance. Interestingly, mitochondrial dysfunction in skeletal muscle and adipose tissue are early events in the development of type II diabetes mellitus and are proposed to play a role in exacerbating insulin resistance. Although it has been demonstrated that skeletal muscle of insulin-resistant individuals has reduced mitochondria and mitochondrial dysfunction, whether this disruption of mitochondrial function is more widespread has not been explored. We hypothesize that this disruption of mitochondrial function is more systemic and thereby may contribute to the development of peripheral insulin resistance and possibly promote the myriad of complications associated with diabetes.

To test these assumptions, we propose an initial proof of concept study to evaluate mitochondrial biology in human platelets in normal volunteers, pre-diabetic and diabetic subjects to assess whether mitochondrial disruption/dysfunction evolves with the progression to type II diabetes. In parallel, proteomic analysis will be performed to evaluate whether the development of insulin resistance and diabetes confers a specific modulation in the biological signature of human platelets with disease progression. To delineate these concepts, we will evaluate study subject's glucose tolerance and insulin sensitivity and draw blood in parallel to study their platelets. Biological readouts will include: 1) the quantification of the mitochondrial proteome and electron transfer chain content; 2) the evaluation of platelet mitochondrial respiratory function and 3) to determine the mitochondrial reactive oxygen species capacity and defenses. If this hypothesis is validated, this study will show that the mitochondrial disruption/dysfunction is a more generalized finding in type II diabetes. Additionally, it would propose the use of platelets as potential biomarkers for early detection of mitochondrial function and assessment of disease. Finally, this would establish a peripheral blood readout of the modification of mitochondrial function as a novel approach to monitor the prevention and/or reversal of insulin resistance and diabetes in response to therapeutic strategies.