Meeting Abstract

P1.45  Tuesday, Jan. 4  Captivity Affects Acute Phase Responses in House Sparrows KIDD, Laura C.*; COON, Courtney; LIEBL, Andrea; MARTIN, Lynn; University of South Florida lkidd@mail.usf.edu

Chronic stressors affect immune function in domesticated animals, but whether the same patterns manifest in wild species is little known. Previous work on a wild songbird, the house sparrow (Passer domesticus), indicated that captivity acted as a chronic stressor and impacted some immune functions. The goal of the present study was to determine whether the acute phase response (APR), a rapid, broadly effective immune response, was damped over time in captivity, as would be expected if chronic stress was immunosuppressive for this wild species. Three cohorts of wild birds were captured and APRs were induced via injections with lipopolysaccharide (a component of Gram-negative bacteria cells walls) either immediately at capture or after two or four weeks in captivity. Pre- and post-injection (4 and 24h) blood samples were collected and levels of Toll-like receptor 4 (TLR4), interleukin-1β (IL-1β), and interleukin-6 (IL-6) mRNA expression (from circulating leukocytes) and circulating corticosterone were measured. TLR-4 is the main recognition molecule for LPS whereas IL-1β and IL-6 are the major avian pro-inflammatory cytokines and corticosterone is a potent anti-inflammatory steroid. Surprisingly, we found that captive birds became hyperinflammatory in that levels of TLR-4, IL-1β, and IL-6 expression were highest in 4-week captive sparrows; indeed, in the other cohorts, responses to the LPS challenge were mild to absent. These results may be due to the robust corticosterone responses to LPS in the wild birds (a response that was absent in the captive ones). Further study is critical to ascertain whether captivity generally suppresses APRs in wild birds, or whether the responses of house sparrows is exceptional given that their status as an introduced species has been demonstrated to have impacted their immune systems.