title: Characterization of early cytokine responses and an interleukin (IL)-6-dependent pathway of endogenous glucocorticoid induction during murine cytomegalovirus infection.
abstract: Early infection with murine cytomegalovirus (MCMV) induces circulating levels of interleukin (IL)-12, interferon (IFN)-gamma, and tumor necrosis factor (TNF). Studies presented here further characterize these responses by defining kinetics and extending evaluation to include IL-1, IL-6, and glucocorticoids. IL-12 p40, IFN-gamma, TNF, IL-1alpha, and IL-6 were shown to be increased, but IL-1beta was undetectable, in serum of MCMV-infected mice. The IL-12 p40, IFN-gamma, TNF, and IL-6 responses were dramatic with peak levels reaching >150-10,000 pg/ml at 32-40 h after infection and rapidly declining thereafter. Glucocorticoid induction, peaking at 36 h and reaching 30-fold increases above control values, accompanied the cytokine responses. Mice with cytokine deficiencies or neutralized cytokine function demonstrated that IL-6 was the pivotal mediator of the glucocorticoid response, with IL-1 contributing to IL-6 production. The IL-6 requirement appeared to be specific for virus-type stimuli as the synthetic analogue of viral nucleic acid, polyinosinic-polycytidylic acid, also induced IL-6-dependent glucocorticoid release, but treatments with the bacterial product lipopolysaccharide and a non-immune physical restraint stressor elicited IL-6-independent responses. Collectively, the results identify IL-6 as a primary mediator of glucocorticoid induction, and elucidate specific pathways of interactions between immune and neuroendocrine systems during viral infection.
authors.affiliation: Division of Biology and Medicine, Brown University, Providence, Rhode Island 02912, USA.
authors.forename: M C
authors.initials: MC
authors.lastname: Ruzek
authors.forename: A H
authors.initials: AH
authors.lastname: Miller
authors.forename: S M
authors.initials: SM
authors.lastname: Opal
authors.forename: B D
authors.initials: BD
authors.lastname: Pearce
authors.forename: C A
authors.initials: CA
authors.lastname: Biron
mesh_terms: D000324:Adrenocorticotropic Hormone / Q000097:blood; D000818:Animals; D003345:Corticosterone / Q000097:blood; D016207:Cytokines / Q000097:blood*; D005938:Glucocorticoids / Q000097:blood*; D006566:Herpesviridae Infections / Q000276:immunology*; D007030:Hypothalamo-Hypophyseal System; D007371:Interferon-gamma / Q000097:blood; D007378:Interleukins / Q000097:blood; D007700:Kinetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D008954:Models, Biological; D018146:Muromegalovirus / Q000276:immunology*; D010913:Pituitary-Adrenal System; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
chemical_list: D016207:Cytokines; D005938:Glucocorticoids; D007378:Interleukins; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D000324:Adrenocorticotropic Hormone; D003345:Corticosterone