Kinetics of endotoxin-induced acute-phase protein gene expression and its modulation by TNF-alpha monoclonal antibody.

The kinetics of cytokine release and acute-phase protein gene expression in liver were investigated in rats receiving a single intraperitoneal bolus dose of Escherichia coli lipopolysaccharide (LPS). Transient elevation of plasma tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6) were detected. Hepatic messenger RNAs for two acute-phase proteins, alpha 1-acid glycoprotein and alpha 2-macroglobulin, were measured by Northern blotting and were found to increase to a maximum at 24 h, returning to normal by 72 h; plasma concentrations showed a slower but more sustained rise. For albumin, hepatic mRNA was reduced, being minimum at 24 h with a similar but more prolonged fall in plasma concentration. Pretreatment of rats with TNF-alpha monoclonal antibody 4 h before LPS ameliorated weight loss and anorexia, partially suppressed the rise in IL-6 and reduced the increase in hepatic mRNA and plasma concentrations of alpha 1-acid glycoprotein and alpha 2-macroglobulin. For albumin, however, such pretreatment had no effect on the fall in either hepatic mRNA or plasma concentration. Thus we have defined an in vivo role of TNF-alpha in the control of endotoxin-induced acute-phase protein generation.