Rapid pulmonary expression of acute-phase reactants after local lipopolysaccharide exposure in mice is followed by an interleukin-6 mediated systemic acute-phase response

This study investigated local and systemic innate immune responses in lipopolysaccharide (LPS)-induced lung inflammation in mice. Intratracheal LPS exposure resulted in increased pulmonary mRNA expression for acute-phase reactants (APRs) alpha(1)-antitrypsin (alpha(1)-AT), alpha(1)-acid glycoprotein (AGP), and LPS-binding protein (LBP) from 4 hours post exposure. Although pulmonary serum amyloid P component (SAP) mRNA was not increased, systemic levels of SAP, AGP, and LBP were elevated from 24 hours post exposure. Systemic APRs increase was associated with hepatic mRNA expression. As in vivo neutralization of interleukin (IL)-6, but not tumor necrosis factor (TNF)-alpha, fully ablated hepatic APR mRNA expression, IL-6 may act as signaling molecule between lung and liver. In conclusion, pulmonary LPS exposure induced rapid APR expression in lung, which precedes IL-6-mediated systemic elevation of APRs associated with hepatic APRs expression.