LPS stimulation of TNF-receptor deficient macrophages: a differential role for TNF-alpha autocrine signaling in the induction of cytokine and nitric oxide production.
To evaluate the role of autocrine TNF-alpha signaling in macrophage activation, immortalized macrophages from normal mice (B6/J2) and from mice containing gene targeted disruptions of the type 1 and type 2 TNF-receptor genes (TRN) were stimulated under CD14-dependent or serum-free conditions. Although the B6/J2 and TRN clones mounted similar nitric oxide responses to LPS in the presence of serum, the TRN macrophages responded poorly when stimulated with LPS under serum free conditions. LPS stimulation of TRN and B6/J2 under serum-free conditions resulted in equivalent levels of IL-1beta, TNF-alpha, and iNOS gene expression. However, Western blot analysis revealed that iNOS protein production by TRN was 2-fold lower than that produced by B6/J2. These results indicate that autocrine TNF-alpha stimulation contributes to the signaling pathways initiated by ligation of LPS receptors in the absence of LBP and is involved in iNOS post-transcriptional regulation.
Clemons-Miller
A R
AR
Department of Microbiology, Quillen College of Medicine, East Tennessee State University, Johnson City, USA.
Cox
G W
GW
Suttles
J
J
Stout
R D
RD
D000818:Animals; D015153:Blotting, Western; D002478:Cells, Cultured; D016895:Culture Media, Serum-Free; D016207:Cytokines / Q000378:metabolism*; D015870:Gene Expression; D007375:Interleukin-1 / Q000032:analysis / Q000235:genetics / Q000378:metabolism; D018950:Lipopolysaccharide Receptors / Q000494:pharmacology; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008262:Macrophage Activation; D008264:Macrophages / Q000187:drug effects* / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009569:Nitric Oxide / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000235:genetics / Q000378:metabolism; D052247:Nitric Oxide Synthase Type II; D018124:Receptors, Tumor Necrosis Factor / Q000172:deficiency / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000502:physiology*
D016895:Culture Media, Serum-Free; D016207:Cytokines; D007375:Interleukin-1; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D018124:Receptors, Tumor Necrosis Factor; D014409:Tumor Necrosis Factor-alpha; D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse