Biomarker Core Laboratory, Foundation for Atlanta Veterans Education and Research, Atlanta Veterans Affairs Health Care System, Atlanta, Georgia, USA
Among the most common non-communicable diseases are obesity, cardiovascular disease, and diabetes, which are responsible for the major cardiometabolic phenotypes. Together with mitochondrial alterations, oxidative stress and inflammation are key molecular mechanisms that contribute to the onset and development of these conditions. Meal consumption is a recurring daily activity that is directly linked to oxidative stress and inflammation. Acute increases in lipids, notably triglycerides, during the postabsorptive period have been suggested to induce a state of inflammation with stimulation of adhesion molecules, cytokines, oxidative stress, and leukocyte activation. Not only lipids but also meal-induced elevations in glucose have also been linked to postprandial oxidative stress and inflammation. The impact of postprandial hypertriglyceridemia and hyperglycemia on oxidative stress and inflammation is not only independent but may be cumulative. It is our hypothesis that, in a system that could not maintain homeostasis to continuous changes of the environment, repeated exposures to meals that provide modest doses of fat and glucose could potentially elicit abnormal responses that contribute to the onset and development of chronic cardiometabolic phenotypes.
Part of the book: Apolipoproteins, Triglycerides and Cholesterol
As inflammatory and oxidative stress are associated with cardiometabolic diseases, detection of abnormal fasting levels of inflammatory and oxidative biomarkers are indicative disease presence and may be too late for any preventive management. Metabolic flexibility refers to the ability of various metabolic processes to compensate for these acute changes and return all metabolites to baseline levels. By monitoring responses of key biomarkers to a standardized physiologic challenge, it is possible to assess the ability of the body to restore homeostasis, that is a measure of metabolic flexibility. Acute changes in lipoprotein-associated biomarkers of oxidative stress have been demonstrated following meal consumption. These include changes in circulating levels of oxidized low-density lipoproteins (LDL), levels of autoantibodies to malondialdehyde-modified LDL, as well as the oxidative susceptibility of isolated plasma LDL. These responses depend on the type and amount of dietary fats in the meal. Management with certain lipid-lowering drugs could also be shown to affect these meal-induced changes. However, plasma levels may be underestimated as we can demonstrate a spike in lipoprotein-associated biomarkers of oxidative stress resulting from the release oxidatively modified epitopes from the arterial wall by an intravenous bolus of heparin.