Grant: Operating Grant

Biochemical stress is a necessary process that can help to resist infection or to repair damaged tissue, yet it causes diseases such as cardiovascular disease. Polyunsaturated fatty acids (PUFA) are a chemical target of a type of stress called reactive oxygen species (ROS). This is thought to be a major cause of cholesterol in arteries. ROS cause PUFA to be broken down into products that contain oxygen as hydroxy and as aldehyde. The breakdown product that we propose to study is called 4-hydroxynonenal (4-HNE). The "4-hydroxy" tells us where the hydroxy is, "non" stands for nine carbons, the "en" stands for a single double bond between two carbons and the "al" stands for the aldehyde. Cells would die when exposed to 4-HNE unless they could convert it to another form. The major biochemical pathway for this conversion uses glutathione. We have found that red blood cells can take up 4-HNE, combining it with glutathione and then exporting from the red blood cell. However, there is evidence that these products are active signals and cause changes in blood clotting and the blood vessels that lead to disease. We have discovered that one product with the specialized name "lactone" is increased in a mouse model with a deficiency of the enzyme paraoxonase 1 (PON1), that develops more cholesterol in its arteries and an increased rate of blood clotting. We have also found that this product is made by red blood cells from patients with diabetes, and from patients undergoing coronary artery bypass graft surgery. In this proposal we will characterize the red blood cell capacity to metabolize 4-HNE by the glutathione pathway. We will test whether the products impair platelet glutathione metabolism, causing increased platelet stickiness. We will test the idea that diabetes causes higher amounts of glutathione to be used to metabolize 4-HNE. Our studies have the potential to identify patients at the highest risk of developing complications from diabetes and cardiovascular diseas