Abstract 1045 Cytokines: Intracellular Signaling Platform, Tuesday, 5/4
LPS-mediated immune responses, including activation of monocytes, macrophages, and endothelial cells (EC) play an important role in the pathogenesis of gram-negative bacteria-induced sepsis syndrome. Activation of NF-κB is thought to be required for cytokine release from LPS-responsive cells, a critical step for endotoxic effects. The molecular mechanisms of the signaling cascade induced by LPS to activate NF-κB are unknown. Furthermore, the signaling LS receptor is still unidentified. Recent studies suggested that a toll like receptor (TLR) might be a signaling receptor that can be activated by LPS. Here we investigated the role and involvement of IL-1 and TNF-signal transducer molecules in LPS signaling in human dermal microvessel EC (HDMEC), and THP-1 monocytic cells. Cell were transfected with reporter genes pCMV-gal and ELAM-NF-κB-luciferase. LPS stimulation of HDMEC and THP-1 cells initiated an IL-1 receptor-like NF-κB signaling cascade (about 10-fold induction of NF-κB luciferase activity). In transient co-transfection experiments, dominant-negative mutants of the IL-1 signaling pathway, including MyD88, IRAK, IRAK2, and TRAF6 inhibited both IL-1- and LPS-induced NF-κB-luciferase activity in both cell types (mean inhibition of about 70-80%, in triplicate experiments). LPS-induced NF-κB activation was not inhibited by a dominant-negative mutant of TRAF2 which is involved in TNF signaling. LPS-induced activation of NF-κB responsive reporter gene was not inhibited by IL-1 receptor antagonist. We have also found that HDMEC and THP-1 express both TLR2 and TLR4, by immunohistochemistry, western blotting and RT-PCR. These findings show for the first time that the LPS signaling cascade uses an analogous molecular framework for signaling as IL-1 in LPS-responsive cells i.e., mononuclear phagocytes and EC, an suggest that a signal transduction molecule in the LPS receptor complex may belong to IL-1 receptor/TLR super family.
(Supported by NIH, A140275 to M.A.)
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Zhang, F., Kirschning, C., Mancinelli, R. et al. Bacterial Lipopolysaccharide (LPS) Activates NF-κB through Interleukin-1 (IL-1) Signaling Mediators in Cultured Human Endothelial Cells and Mononuclear Phagocytes. Pediatr Res 45, 179 (1999). https://doi.org/10.1203/00006450-199904020-01062
Issue Date:
DOI: https://doi.org/10.1203/00006450-199904020-01062