%0 Journal Article
%T NF-¦ÊB p50 facilitates neutrophil accumulation during LPS-induced pulmonary inflammation
%A Joseph P Mizgerd
%A Michal M Lupa
%A Matt S Spieker
%J BMC Immunology
%D 2004
%I BioMed Central
%R 10.1186/1471-2172-5-10
%X In contrast to previous results with living E. coli, neutrophil accumulation elicited by E. coli LPS in the lungs was decreased by p50 deficiency, to approximately 30% of wild type levels. Heat-killed E. coli induced neutrophil accumulation which was not decreased by p50 deficiency, demonstrating that bacterial growth and metabolism were not responsible for the different responses to bacteria and LPS. p50 deficiency increased the LPS-induced expression of ¦ÊB-regulated genes essential to neutrophil recruitment, including KC, MIP-2, ICAM-1, and TNF-¦Á suggesting that p50 normally limited this gene expression and that decreased neutrophil recruitment did not result from insufficient expression of these genes. Neutrophils were responsive to the chemokine KC in the peripheral blood of p50-deficient mice with or without LPS-induced pulmonary inflammation. Interleukin-6 (IL-6), previously demonstrated to decrease LPS-induced neutrophil recruitment in the lungs, was increased by p50 deficiency, but LPS-induced neutrophil recruitment was decreased by p50 deficiency even in IL-6 deficient mice.p50 makes essential contributions to neutrophil accumulation elicited by LPS in the lungs. This p50-dependent pathway for neutrophil accumulation can be overcome by bacterial products other than LPS and does not require IL-6.The innate immune response to bacteria in the lungs requires the recruitment and activation of neutrophils, mediated by the coordinated expression of diverse genes (see [1] for review). In rodents, neutrophils recognize at least 2 chemokines (KC and macrophage inflammatory protein-2, MIP-2) that are synthesized de novo in response to gram-negative bacteria or LPS in the lungs, and each is independently essential to maximal neutrophil recruitment [2-4]. Neutrophils also recognize the adhesion molecule intercellular adhesion molecule-1 (ICAM-1). ICAM-1 is constitutively expressed, but LPS and gram-negative bacteria in the lungs result in increased expression [5,6] and
%U http://www.biomedcentral.com/1471-2172/5/10