Inflammation As a Biomarker Method in Lifespan Developmental Methodology

Abstract

Inflammatory markers provide invaluable tools for studying health and disease across the lifespan. Inflammation is central to the immune system’s response to infection and wounding; it also can increase in response to psychosocial stress. In addition, depression and physical symptoms such as pain and poor sleep can promote inflammation and, because these factors fuel each other, all contribute synergistically to rising inflammation. With increasing age, persistent exposure to pathogens and stress can induce a chronic proinflammatory state, a process known as inflamm-aging. Inflammation’s relevance spans the life course, from childhood to adulthood to death. Infection-related inflammation and stress in childhood, and even maternal stress during pregnancy, may presage heightened inflammation and poor health in adulthood. In turn, chronically heightened inflammation in adulthood can foreshadow frailty, functional decline, and the onset of inflammatory diseases in older age. The most commonly measured inflammatory markers include C-reactive protein (CRP) and proinflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α). These biomarkers are typically measured in serum or plasma through blood draw, which capture current circulating levels of inflammation. Dried blood spots offer a newer, sometimes less expensive collection method but can capture only a limited subset of markers. Due to its notable confounds, salivary sampling cannot be recommended. Inflammatory markers can be added to a wide range of lifespan developmental designs. Incorporating even a single inflammatory assessment to an existing longitudinal study can allow researchers to examine how developmental profiles and inflammatory status are linked, but repeated assessments must be used to draw conclusions about the associations’ temporal order and developmental changes. Although the various inflammatory indices can fluctuate from day to day, ecological momentary assessment and longitudinal burst studies have not yet incorporated daily inflammation measurement; this represents a promising avenue for future research. In conclusion, mounting evidence suggests that inflammation affects health and disease across the lifespan and can help to capture how stress “gets under the skin.” Incorporating inflammatory biomarkers into developmental studies stands to enhance our understanding of both inflammation and lifespan development.

Pain Is Associated With Depressive Symptoms, Inflammation, and Poorer Physical Function in Older Adults With HIV

“…Similarly, adjusted linear regression models were used to test the relationship between pain and inflammation levels. We also conducted ancillary analyses adjusting for anti-inflammatory medication use and ancillary sensitivity analyses among those with CRP levels less than 10 mg/l (a common threshold for acute illness and analyses that focus on low-grade inflammation) (35,42,43), to determine whether the patterns were consistent in this subgroup. To determine whether the relationship between pain and the cytokine composite were driven by one or more of the individual cytokines, we conducted ancillary analyses to test the relationship between pain and individual cytokines in unadjusted and adjusted regression analyses.…”

Salivary biomarkers: novel noninvasive tools to diagnose chronic inflammation

“…Methods for saliva sampling and collection Saliva has largely been disregarded in the past due to the presence of several food contaminants in its biochemical profile, as well as paucity of demonstration of correlations between salivary and blood markers. 55 However, several studies have recently highlighted how saliva well correlates with blood markers, thus representing a promising alternative for noninvasive diagnostics, 56 as it is the case with glucose 57 and cortisol. 58 Among others, IL-6, an inflammatory marker, also shows a significant correlation between blood and saliva 59 (Table 1).…”

Childhood sexual abuse history amplifies the link between disease burden and inflammation among older adults with HIV

“…This analysis included 131 participants who completed the psychosocial and biomedical study visits, had data available for childhood trauma and inflammation variables, and had CRP levels below 10 ​mg/L, a threshold indicating likely acute infection ( Boylan and Ryff, 2013 ; Pearson et al., 2003 ; S. J. Wilson et al., 2018 ).…”

“…Adjusted models included age, sex, race, BMI, smoking status, anti-inflammatory medication use, SSRI medication use, and depressive symptoms, based on broader literature suggesting their consistent links with inflammation ( Lu et al., 2019 ; S. J. Wilson et al., 2018 ). Ancillary analyses adjusted for PTSD symptom scores and experiencing IPV.…”