title: Age differences in cytokine expression under conditions of health using experimental pain models.
abstract: Older adults are at an increased risk to develop frequent and prolonged pain. Emerging evidence proposes a link between immune changes and pain, which is consistent with the inflammation theory of aging and the increased incidence of age-related diseases. This study tested the hypothesis that older adults show greater immune responses to experimental pain compared to younger individuals. Study subjects (8 younger and 9 older healthy adults) underwent 3 experimental sessions using well-validated human experimental pain models: the cold pressor task (CPT), focal heat pain (FHP), and a non-painful thermal control. Blood was collected through an indwelling catheter at baseline and 3, 15, 30, 45, 60, and 90 min post-stimuli administration. Pro-inflammatory cytokines (TNF-α IL-6 and IL-8) peaked at the same time points for both groups, with greater elevations among older subjects for TNF-α and IL-8 in both pain models and elevations in IL-6 only for CPT. Anti-inflammatory cytokines (IL-4, IL-5, and IL-10) generally peaked later for the older subjects, with increased elevations for FHP but not the CPT. These data are consistent with the assertion that age-related immune system dysregulation may account for the increased prevalence of pain in older adults.
authors.affiliation: Pain Research & Intervention Center of Excellence (PRICE), United States; Institute of Aging, College of Medicine, United States; Department of Community Dentistry and Behavioral Science, College of Dentistry, United States.
authors.forename: Yenisel
authors.initials: Y
authors.lastname: Cruz-Almeida
authors.affiliation: Pain Research & Intervention Center of Excellence (PRICE), United States; Department of Community Dentistry and Behavioral Science, College of Dentistry, United States.
authors.forename: Maria
authors.initials: M
authors.lastname: Aguirre
authors.affiliation: Department of Oral Biology, College of Dentistry, United States.
authors.forename: Heather L
authors.initials: HL
authors.lastname: Sorenson
authors.affiliation: Pain Research & Intervention Center of Excellence (PRICE), United States; Department of Anesthesiology, College of Medicine, United States.
authors.forename: Patrick
authors.initials: P
authors.lastname: Tighe
authors.affiliation: Department of Oral Biology, College of Dentistry, United States.
authors.forename: Shannon M
authors.initials: SM
authors.lastname: Wallet
authors.affiliation: Pain Research & Intervention Center of Excellence (PRICE), United States; Department of Community Dentistry and Behavioral Science, College of Dentistry, United States.
authors.forename: Joseph L
authors.initials: JL
authors.lastname: Riley
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000375:Aging / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D016207:Cytokines / Q000097:blood*; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D007249:Inflammation / Q000276:immunology*; D015850:Interleukin-6 / Q000097:blood; D016209:Interleukin-8 / Q000097:blood; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000276:immunology*; D010147:Pain Measurement; D014409:Tumor Necrosis Factor-alpha / Q000097:blood; D055815:Young Adult
chemical_list: D015415:Biomarkers; C508606:CXCL8 protein, human; D016207:Cytokines; C508600:IL6 protein, human; D015850:Interleukin-6; D016209:Interleukin-8; C439524:TNF protein, human; D014409:Tumor Necrosis Factor-alpha
keywords: Acute pain; Aging; Anti-inflammatory; Biomarkers; Cytokine; Experimental pain; Pain; Pro-inflammatory