Acute lung injury induced by lipopolysaccharide is independent of complement activation.
Although acute lung injury (ALI) is an important problem in humans, its pathogenesis is poorly understood. Airway instillation of bacterial LPS, a known complement activator, represents a frequently used model of ALI. In the present study, pathways in the immunopathogenesis of ALI were evaluated. ALI was induced in wild-type, C3(-/-), and C5(-/-) mice by airway deposition of LPS. To assess the relevant inflammatory mediators, bronchoalveolar lavage fluids were evaluated by ELISA analyses and various neutralizing Abs and receptor antagonists were administered in vivo. LPS-induced ALI was neutrophil-dependent, but it was not associated with generation of C5a in the lung and was independent of C3, C5, or C5a. Instead, LPS injury was associated with robust generation of macrophage migration inhibitory factor (MIF), leukotriene B(4) (LTB4), and high mobility group box 1 protein (HMGB1) and required engagement of receptors for both MIF and LTB4. Neutralization of MIF or blockade of the MIF receptor and/or LTB4 receptor resulted in protection from LPS-induced ALI. These findings indicate that the MIF and LTB4 mediator pathways are involved in the immunopathogenesis of LPS-induced experimental ALI. Most strikingly, complement activation does not contribute to the development of ALI in the LPS model.
Rittirsch
Daniel
D
Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
Flierl
Michael A
MA
Day
Danielle E
DE
Nadeau
Brian A
BA
McGuire
Stephanie R
SR
Hoesel
Laszlo M
LM
Ipaktchi
Kyros
K
Zetoune
Firas S
FS
Sarma
J Vidya
JV
Leng
Lin
L
Huber-Lang
Markus S
MS
Neff
Thomas A
TA
Bucala
Richard
R
Ward
Peter A
PA
D000818:Animals; D001992:Bronchoalveolar Lavage Fluid / Q000276:immunology; D003167:Complement Activation; D003165:Complement System Proteins / Q000276:immunology / Q000378:metabolism*; D004195:Disease Models, Animal; D024243:HMGB1 Protein / Q000276:immunology / Q000378:metabolism*; D018836:Inflammation Mediators / Q000378:metabolism; D007975:Leukotriene B4 / Q000276:immunology / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000276:immunology*; D008168:Lung / Q000276:immunology / Q000378:metabolism; D008263:Macrophage Migration-Inhibitory Factors / Q000276:immunology / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008817:Mice, Mutant Strains; D012128:Respiratory Distress Syndrome / Q000276:immunology* / Q000378:metabolism
D024243:HMGB1 Protein; D018836:Inflammation Mediators; D008070:Lipopolysaccharides; D008263:Macrophage Migration-Inhibitory Factors; D007975:Leukotriene B4; D003165:Complement System Proteins