A team of scientists at Emory University School of Medicine has identified a direct link between oxidative stress and inflammatory signals in the blood.
The finding could lead to improved strategies for preventing several diseases by including antioxidants in the diet and for reducing the impact of inflammation in critically ill patients by adding cysteine to intravenous or tube feeding.
The results are published online this week in the journal PLoS One .
Many normal metabolic functions produce reactive forms of oxygen that can damage cells. Oxidative stress, a disruption of the body's ability to control reactive forms of oxygen, has been connected with heart disease, diabetes and several neurodegenerative diseases.
However, scientists are still learning about the best ways to measure and reduce oxidative stress, says Dean P. Jones, PhD, professor of medicine and director of the Clinical Biomarkers Laboratory at Emory University School of Medicine. For example, large-scale clinical trials have shown little benefit in supplementing the diet with antioxidants such as vitamins C and E.
Jones and his colleagues, including Thomas R. Ziegler, MD of the Emory Department of Medicine, have been concentrating on a measure of oxidative stress in the blood: cysteine, an amino acid found in most proteins in the body. Cysteine can exist in two forms: oxidized and reduced. The higher the level of oxidative stress outside the cell, the more oxidized cysteine there is. Other indicators such as glutathione are more important inside cells.
Several studies have shown that levels of oxidized cysteine in the blood tend to rise as people age. Smoking and alcohol consumption are also linked with higher levels of oxidized cysteine. In addition, Jones and Ziegler have found that critical illness and malnutrition are associated with oxidative stress and oxidized cysteine in the blood.
Working with Jones, graduate student Smita Iyer and immunologist Mauricio Rojas, MD, found that a high level of oxidized cysteine drives white blood cells to send out inflammatory messages in the form of the protein IL-1 beta.