title: Interleukin 37 expression in mice alters sleep responses to inflammatory agents and influenza virus infection.
abstract: Multiple interactions between the immune system and sleep are known, including the effects of microbial challenge on sleep or the effects of sleep loss on facets of the immune response. Cytokines regulate, in part, sleep and immune responses. Here we examine the role of an anti-inflammatory cytokine, interleukin-37 (IL-37) on sleep in a mouse strain that expresses human IL-37b (IL37tg mice). Constitutive expression of the IL-37 gene in the brains of these mice under resting conditions is low; however, upon an inflammatory stimulus, expression increases dramatically. We measured sleep in three conditions; a) under baseline conditions and after 6 h of sleep loss, b) after bolus intraperitoneal administration of lipopolysaccharide (LPS) or IL-1β and c) after intranasal influenza virus challenge. Under baseline conditions, the IL37tg mice had 7% more spontaneous non-rapid eye movement sleep (NREMS) during the light period than wild-type (WT) mice. After sleep deprivation both WT mice and IL37tg mice slept an extra 21% and 12%, respectively, during the first 6 h of recovery. NREMS responses after sleep deprivation did not significantly differ between WT mice and IL37tg mice. However, in response to either IL-1β or LPS, the increases in time spent in NREMS were about four-fold greater in the WT mice than in the IL37tg mice. In contrast, in response to a low dose of mouse-adapted H1N1 influenza virus, sleep responses developed slowly over the 6 day recording period. By day 6, NREMS increased by 10% and REMS increased by 18% in the IL37tg mice compared to the WT mice. Further, by day 4 IL37tg mice lost less weight, remained more active, and retained their body temperatures closer to baseline values than WT mice. We conclude that conditions that promote IL-37 expression attenuate morbidity to severe inflammatory challenge.
authors.affiliation: Elson S. Floyd College of Medicine, Department of Biomedical Sciences, Washington State University, Spokane, WA, USA 99210-1495.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Davis
authors.affiliation: Elson S. Floyd College of Medicine, Department of Biomedical Sciences, Washington State University, Spokane, WA, USA 99210-1495; VA Boston Healthcare System, Harvard Medical School, West Roxbury, MA, USA 02312; Department of Psychiatry, Harvard Medical School, West Roxbury, MA, USA 02312.
authors.forename: Mark R
authors.initials: MR
authors.lastname: Zielinski
authors.affiliation: Elson S. Floyd College of Medicine, Department of Biomedical Sciences, Washington State University, Spokane, WA, USA 99210-1495.
authors.forename: Danielle
authors.initials: D
authors.lastname: Dunbrasky
authors.affiliation: Elson S. Floyd College of Medicine, Department of Biomedical Sciences, Washington State University, Spokane, WA, USA 99210-1495.
authors.forename: Ping
authors.initials: P
authors.lastname: Taishi
authors.affiliation: Department of Medicine, University of Colorado Denver, Aurora, CO, USA 80045; Radboud University Medical Center, Nijmegen, The Netherlands.
authors.forename: Charles A
authors.initials: CA
authors.lastname: Dinarello
authors.affiliation: Elson S. Floyd College of Medicine, Department of Biomedical Sciences, Washington State University, Spokane, WA, USA 99210-1495.
authors.forename: James M
authors.initials: JM
authors.lastname: Krueger
keywords: IL-1F7; IL-37; body weight; influenza virus H1N1; interleukin-1β; lipopolysaccharide; sleep deprivation