Chronic infections are associated with an increased composite inflammation index in adult residents of central North Carolina

Abstract

Background. Our previously presented results of the ongoing epidemiological study in North Carolina showed that residential tree cover was associated with a reduced composite index of chronic inflammation in individuals who spent at least 30 min per day outdoors. The objective of present analysis was to assess the effects of chronic infections on the same outcome. Methods. This cross-sectional study involved 335 adults residing in the Raleigh-Durham-Chapel Hill, NC urban area. Blood samples were tested for biomarkers of immune, neuroendocrine, and metabolic functions. Serum immunoglobulin G responses to Toxoplasma gondii, Helicobacter pylori and cytomegalovirus were measured using diagnostic ELISA assays. A Poisson-distributed index of immune function activation/chronic inflammation was estimated as a sum of potentially unhealthy values of the following biomarkers: interferon (IFN)-γ, interleukin (IL)-1β, IL-4, IL-6, IL-8, IL-10, IL-17, tumor necrosis factor (TNF)-α, C-reactive protein, myeloperoxidase, serum amyloid A, chromogranin A, vascular cell adhesion molecule (VCAM)-1, intracellular adhesion molecule (ICAM)-1, eosinophils, monocytes, and neutrophils. Results. Each chronic infection had an independent effect on the immune function index. Preliminary results show that individuals who were seropositive to one, two or three chronic infections had 24% (95% confidence interval: 0%, 55%), 71% (32%, 122%), and 135% (60%, 247%) greater mean inflammation index compared to individuals who were seronegative to all three pathogens, respectively, after adjusting for sociodemographic and behavioral variables, and body mass index. In the same model, self-reported sleep problems and daily screen time greater than 2 hours were associated with 22% (1%, 47%) and 40% (14%, 73%) greater inflammation index, respectively, while greater amounts of time spent outdoors had significant protective effects. Conclusions. Adjusting for the effects of chronic infections on chronic inflammation is important in epidemiological research on health effects of chronic stress and the community environment. This abstract does not represent EPA policy.