In vivo biologic and immunohistochemical analysis of interleukin-1 alpha, beta and tumor necrosis factor during experimental endotoxemia. Kinetics, Kupffer cell expression, and glucocorticoid effects.
Using a model of sepsis induced by parenteral challenge of mice with bacterial lipopolysaccharide (LPS), the authors analyzed the in vivo expression of interleukin-1 (IL-1) alpha,beta and tumor necrosis factor (TNF). Both TNF and IL-1 alpha,beta were detected in hepatic sinusoidal macrophages (Kupffer cells), immunohistochemically. Kinetic analysis showed a clear sequence of synthesis. Tumor necrosis factor was produced first, reaching maximal expression at 1 hour after LPS challenge, then rapidly disappeared. IL-1 beta followed, reaching maximal expression at 2 to 3 hours, then dropped off by 6 hours. Interleukin-1 alpha expression reached a peak at 6 hours and had disappeared by 18 hours. Analysis of serum bioactivity also revealed sequential expression that correlated with immunohistochemical findings. Tumor necrosis factor was maximal at 1 hour and IL-1 at 6 hours. The IL-1 bioactivity was not due to interleukin-6 (IL-6), as this was depleted from specimens by immunoabsorption. Also IL-6 bioactivity reached maximal levels at 3 hours, earlier than IL-1. Pretreatment with 4 mg/kg dexamethasone significantly decreased Kupffer cell expression of TNF and IL-1 alpha (about 80% and 60% suppression, respectively) but had less effect on IL-1 beta expression (about 30% suppression). Accordingly, serum levels of TNF were suppressed by 75% while serum IL-1 was decreased by 39%, indicating differential sensitivity of these cytokines to glucocorticoids. Endogenous corticosteroid levels increased as TNF levels decreased, supporting the contention that glucocorticoids regulate TNF synthesis. In contrast, IL-1 levels rose concurrently with corticosterone. These data indicate a sequential activation of cytokine gene expression in vivo, which may be critical to the cascade of events leading to septic shock, and provide evidence that Kupffer cells are a major source of cytokines in endotoxemia. Finally, the differential sensitivity of cytokine expression to glucocorticoids may in part explain the inadequacy of the latter in the treatment of sepsis.
Chensue
S W
SW
Department of Pathology, Veterans Affairs Medical Center, Ann Arbor, MI 48105.
Terebuh
P D
PD
Remick
D G
DG
Scales
W E
WE
Kunkel
S L
SL
D000818:Animals; D003345:Corticosterone / Q000097:blood; D003907:Dexamethasone / Q000494:pharmacology*; D004731:Endotoxins / Q000097:blood*; D004926:Escherichia coli; D007150:Immunohistochemistry; D007375:Interleukin-1 / Q000097:blood / Q000378:metabolism*; D015850:Interleukin-6 / Q000097:blood; D007700:Kinetics; D007728:Kupffer Cells / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D051379:Mice; D008815:Mice, Inbred Strains; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D004731:Endotoxins; D007375:Interleukin-1; D015850:Interleukin-6; D008070:Lipopolysaccharides; D014409:Tumor Necrosis Factor-alpha; D003907:Dexamethasone; D003345:Corticosterone