title: Exogenous ceramide-1-phosphate reduces lipopolysaccharide (LPS)-mediated cytokine expression.
abstract: Toll-like receptor 4 (TLR4) is a component of the innate immune system that recognizes a diverse group of molecular structures, such as lipopolysaccharide (LPS) from Gram-negative bacteria. TLR4 signaling ultimately leads to activation of the transcription factor, nuclear factor κB (NF-κB), and the production of cytokines. Ceramide is a bioactive sphingolipid that has been suggested to regulate TLR4-induced NF-κB signaling, although reports on the role of ceramide in TLR4 activation conflict. We investigated the possibility that ceramide metabolites, such as ceramide-1-phosphate (C-1-P), may explain these discrepancies. We now report that exogenous C-1-P, but not ceramide, reduces NF-κB-mediated gene transcription in HEK 293 cells stably transfected with human TLR4, CD14, and MD-2. We demonstrate that inhibition of NF-κB by exogenous C-1-P is dose-dependent and specific to TLR4 in a reporter assay. We further demonstrate a requirement for both the phosphate moiety and the sphingoid backbone to inhibit LPS-activated NF-κB transcription. Specifically, C-1-P prevents the degradation of IκB, the phosphorylation of the p65 subunit of NF-κB, and LPS-stimulated MAPK activation. The functional consequence of C-1-P inhibition of NF-κB is a reduction in LPS-mediated cytokine release from HEK 293 TLR4-expressing cells and human peripheral blood mononuclear cells. Taken together, these data demonstrate that C-1-P may function as an anti-inflammatory lipid mediator of immune response.
authors: Department of Pharmacology, Penn State University College of Medicine, Hershey, Pennsylvania 17033, USA.
authors: Jody L
authors: JL
authors: Hankins
authors: Todd E
authors: TE
authors: Fox
authors: Brian M
authors: BM
authors: Barth
authors: Kellee A
authors: KA
authors: Unrath
authors: Mark
authors: M
authors: Kester
mesh_terms: D002518:Ceramides / Q000276:immunology / Q000494:pharmacology*; D016207:Cytokines / Q000096:biosynthesis* / Q000235:genetics / Q000276:immunology; D057809:HEK293 Cells; D006801:Humans; D020672:I-kappa B Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D018950:Lipopolysaccharide Receptors / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D008070:Lipopolysaccharides / Q000276:immunology / Q000494:pharmacology*; D051218:Lymphocyte Antigen 96 / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D016328:NF-kappa B / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D059748:Proteolysis / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects* / Q000502:physiology; D051197:Toll-Like Receptor 4 / Q000276:immunology / Q000378:metabolism*; D014158:Transcription, Genetic / Q000187:drug effects / Q000502:physiology
chemical_list: D002518:Ceramides; D016207:Cytokines; D020672:I-kappa B Proteins; C495377:LY96 protein, human; D018950:Lipopolysaccharide Receptors; D008070:Lipopolysaccharides; D051218:Lymphocyte Antigen 96; D016328:NF-kappa B; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; C065576:ceramide 1-phosphate; C440499:lipopolysaccharide, Escherichia coli O111 B4