James Edwards

Metabolomics of Diabetic Complications. Bioanalytical Chemistry, Biochemistry, Mass Spectrometry.

Diabetes is the leading cause of blindness, end-stage renal disease and lower extremity amputations in the U.S. Excessive glucose metabolism in endothelial cells induces oxidative stress which ultimately compromises cellular integrity. While this aspect of diabetic complications is well established, the role of metabolic aberrations has been generally neglected. Advances in metabolite profiling through high sensitivity mass spectrometry is now capable of analyzing hundreds of metabolites in a single run. These capabilities hold the potential of discovering unforeseen biochemical dysfunctions, elucidate pathophysiologies and reveal novel therapeutic targets. The research focus of the Edwards Laboratory is to investigate metabolic perturbations and therapeutics of diabetic complications using multiple biochemical and bio-analytical techniques.

1. Investigate metabolic aberrations in hyperglycemia damaged endothelial cells and evaluate therapeutic efficacy on diabetic retinopathy The flooding of glucose into endothelial cells induces metabolic dysfunctions in diabetes. Diabetic complications research has focused on four or five major pathways as therapeutic targets. Despite overwhelmingly positive evidence in the lab, drugs targeting these discrete pathways have generally failed to alleviate the pathology in clinical trials. This indicates that these previous therapeutics may have "overlooked" certain metabolic pathways. With the advent of new capillary liquid chromatography and mass spectrometry technologies, considerably more metabolites can be detected, identified and quantified. We will investigate metabolic dysfunction in vitro and target therapeutics (or combinations of therapeutics) toward these pathways. Therapies which correct for metabolism in vitro will be carried to in vivo analysis for efficacy in treating diabetic retinopathy. By ensuring therapies correct metabolic dysfunctions in vitro, transition to and success in in vivo models will be dramatically improved.
2. Discover biomarker for diabetic complications. Prophylactic options for diabetic complications are generally limited outside of tighter blood glucose control. To date, the only prognostic indicator of risk of complications is HbA1C, which measures the average blood glucose level. While average blood glucose levels show correlations with complications, data suggests that this is not a sufficient indicator. Rather fluctuation in blood glucose levels which dramatically increase oxidative stress is hypothesized to be a prominent cause of complications. Assays for oxidative stress are being developed to assess the risk of developing diabetic complications.
3. Develop high sensitivity mass spectrometry based metabolomic technologies Collectively, mammalian cells have ~3,000 metabolites. High sensitivity capillary based liquid chromatography systems coupled to mass spectrometry can currently analyze about 500 metabolites. We will use high resolution mass spectrometry coupled with novel separation strategies to increase the sensitivity of our instrumentation and increase the number of metabolites analyzed in a single run. Taking advantage of discrete chemistries, we can further identification of previously undiscovered metabolites. These systems will allow us to better understand fundamental biochemical questions. Pushing the analytical boundaries to higher sensitivity and more rapid analyses are essential to the success of the applications discussed above.