title: Investigation on the agonistic and antagonistic biological activities of synthetic Chlamydia lipid A and its use in in vitro enzymatic assays.
abstract: The synthetic 1,4'-bisphosphorylated penta-acyl and tetra-acyl lipid A structures representing the major molecular species of natural chlamydial lipid A were tested for their endotoxic activities as measured by interleukin-8 release from human embryonic kidney (HEK) 293 cells expressing Toll-like receptor (TLR) 2 or TLR4. Both compounds were unable to activate HEK293 cells transiently transfected with TLR2. The penta-acyl lipid A was a weak activator of HEK293 cells expressing TLR4/MD-2/CD14 whereas tetra-acyl lipid A was inactive even at high concentrations. The weak activity of the penta-acyl lipid A could be antagonized by the tetra-acyl derivative of Escherichia coli lipid A (compound 406) or the anti-CD14 monoclonal antibody MEM-18. Both, tetra- and pentaacyl lipid A were unable to antagonize the activity of synthetic E. coli-type lipid A (compound 506) or smooth lipopolysaccharide of Salmonella enterica serovar Friedenau. Tetra- and penta-acyl lipid A served as acceptors for Kdo transferases from E. coli, Chlamydia trachomatis and Chlamydophila psittaci as shown by in vitro assays and detection of the products by thin layer chromatography and immune staining with monoclonal antibody.
authors.affiliation: Leibniz Center for Medicine and Biosciences, Research Center Borstel, Borstel, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Heine
authors.forename: Sabine
authors.initials: S
authors.lastname: Gronow
authors.forename: Alla
authors.initials: A
authors.lastname: Zamyatina
authors.forename: Paul
authors.initials: P
authors.lastname: Kosma
authors.forename: Helmut
authors.initials: H
authors.lastname: Brade
mesh_terms: D002460:Cell Line; D002689:Chlamydia / Q000737:chemistry*; D006017:Glycolipids / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D016209:Interleukin-8 / Q000819:agonists / Q000378:metabolism*; D008050:Lipid A / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D018950:Lipopolysaccharide Receptors / Q000276:immunology / Q000378:metabolism; D051218:Lymphocyte Antigen 96 / Q000819:agonists / Q000276:immunology / Q000378:metabolism; D011994:Recombinant Proteins; D051193:Toll-Like Receptors / Q000819:agonists / Q000378:metabolism; D014162:Transfection; D014166:Transferases / Q000235:genetics / Q000378:metabolism*
chemical_list: C508606:CXCL8 protein, human; D006017:Glycolipids; D016209:Interleukin-8; C495377:LY96 protein, human; D008050:Lipid A; D018950:Lipopolysaccharide Receptors; D051218:Lymphocyte Antigen 96; D011994:Recombinant Proteins; D051193:Toll-Like Receptors; C040142:lipid A precursors, bacterial; D014166:Transferases; C019917:3-deoxy-D-manno-octulosonate transferase