title: Human antiphospholipid antibodies induce TNFalpha in monocytes via Toll-like receptor 8.
abstract: The antiphospholipid syndrome (APS) is characterized by recurrent arterial and/or venous thromboses, pregnancy loss and the presence of antiphospholipid antibodies (aPL). One of the discussed mechanisms of this thrombotic activity in APS patients is attributed to TNFalpha secretion in monocytes after aPL stimulation. To investigate this mechanism in detail, we employed a monoclonal aPL and IgG fractions of APS patients for stimulation of human peripheral monocytes. Stimulation with this monoclonal aPL resulted in an increased expression and secretion of TNFalpha, caused by specific upregulation of TLR8 mRNA and protein expression levels. To confirm the specificity of this finding we could demonstrate that the TNFalpha enhancement could be neutralized by a TLR8-specific inhibitory DNA-oligonucleotide and could be further increased by adding the specific ligands for TLR8. Using APS patients IgG fractions for stimulation of peripheral monocytes revealed a similar TLR8 mRNA elevation and increase in TNFalpha-production. Furthermore the TLR8 expression level in PBMC's of APS patients was as well significantly elevated. It could be demonstrated that the TNFalpha release in monocytes resulting from aPL stimulation was exclusively induced by TLR8 engagement. This could be confirmed in PBMC's of APS patients, hinting that endogenous stimulation of TLR8 in APS patients and consecutive elevation of TNFalpha promotes a proinflammatory environment.
authors.affiliation: Institute of Clinical Chemistry and Laboratory Medicine, Johannes Gutenberg University, Langenbeckstr. 1, 55131 Mainz, Germany.
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Döring
authors.forename: Julia
authors.initials: J
authors.lastname: Hurst
authors.forename: Mareike
authors.initials: M
authors.lastname: Lorenz
authors.forename: Nadine
authors.initials: N
authors.lastname: Prinz
authors.forename: Natascha
authors.initials: N
authors.lastname: Clemens
authors.forename: Maik D
authors.initials: MD
authors.lastname: Drechsler
authors.forename: Stefan
authors.initials: S
authors.lastname: Bauer
authors.forename: Joab
authors.initials: J
authors.lastname: Chapman
authors.forename: Yehuda
authors.initials: Y
authors.lastname: Shoenfeld
authors.forename: Miri
authors.initials: M
authors.lastname: Blank
authors.forename: Karl J
authors.initials: KJ
authors.lastname: Lackner
authors.forename: Philipp
authors.initials: P
authors.lastname: von Landenberg
mesh_terms: D017152:Antibodies, Antiphospholipid / Q000276:immunology*; D000911:Antibodies, Monoclonal / Q000276:immunology / Q000378:metabolism; D016736:Antiphospholipid Syndrome / Q000276:immunology* / Q000378:metabolism; D015153:Blotting, Western; D002469:Cell Separation; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006801:Humans; D009000:Monocytes / Q000276:immunology* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D051200:Toll-Like Receptor 8 / Q000276:immunology* / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000276:immunology* / Q000378:metabolism
chemical_list: D017152:Antibodies, Antiphospholipid; D000911:Antibodies, Monoclonal; C495349:TLR8 protein, human; D051200:Toll-Like Receptor 8; D014409:Tumor Necrosis Factor-alpha