Biomarkers of Stress and Inflammation in Children.

Children are increasingly exposed to stressors that can affect their immune function. Given the possible negative effects of stress and inflammation on health, researchers need to use appropriate biomarkers to measure both the effects of stress and subsequent inflammatory responses. The purpose of this paper is to briefly review stress and inflammatory pathways, identify biomarkers used to measure chronic stress and chronic inflammation particularly in children in clinical and community settings, and to discuss methodological considerations when measuring stress and inflammation in children. Biomarkers of chronic stress can be classified as central, meaning they are made in the brain, or peripheral, meaning they are made in the peripheral tissues in response to central signals. The peripheral biomarker, cortisol, is most frequently used in the community setting. In addition, indirect measures, such as oxytocin, may complement the assessment of stress. Common biomarkers of chronic inflammation in children are C-reactive protein (CRP), TNF-α, and IL-6. Similarly, indirect biomarkers of chronic inflammation, such as IL-2 and IL-1β, may also be considered. Various types of specimens can be used to measure these biomarkers of stress and inflammation including blood, saliva, urine, sweat, hair, nails, and tears. Each type of specimen has different requirements for collection, storage, and assay. Future research would benefit from standardized biomarker levels across age and development in children and incorporation of other biomarkers.