title: Toll-like receptor (TLR)-4 mediates anti-β2GPI/β2GPI-induced tissue factor expression in THP-1 cells.
abstract: Our previous study demonstrated that annexin A2 (ANX2) on cell surface could function as a mediator and stimulate tissue factor (TF) expression of monocytes by anti-β₂-glycoprotein I/β₂-glycoprotein I complex (anti-β₂GPI/β₂GPI). However, ANX2 is not a transmembrane protein and lacks the intracellular signal transduction pathway. Growing evidence suggests that Toll-like receptor 4 (TLR-4) might act as an 'adaptor' for intracellular signal transduction in anti-β₂GPI/β₂GPI-induced TF expressing cells. In the current study, we investigated the roles of TLR-4 and its related molecules, myeloid differentiation protein 2 (MD-2) and myeloid differentiation factor 88 (MyD88), in anti-β₂GPI/β₂GPI-induced TF expressing human monocytic-derived THP-1 (human acute monocytic leukaemia) cells. The relationship of TLR-4 and ANX2 in this process was also explored. Along with TF, expression of TLR-4, MD-2 and MyD88 in THP-1 cells increased significantly when treated by anti-β₂GPI (10 µg/ml)/β₂GPI (100 µg/ml) complex. The addition of paclitaxel, which competes with the MD-2 ligand, could inhibit the effects of anti-β₂GPI/β₂GPI on TLR-4, MD-2, MyD88 and TF expression. Both ANX2 and TLR-4 in THP-1 cell lysates could bind to β₂GPI that had been conjugated to a column (β₂GPI-Affi-Gel). Furthermore, TLR-4, MD-2, MyD88 and TF expression was remarkably diminished in THP-1 cells infected with ANX2-specific RNA interference (RNAi) lentivirus (LV-RNAi-ANX2), in spite of treatment with a similar concentration of anti-β₂GPI/β₂GPI complex. These results indicate that TLR-4 and its signal transduction pathway contribute to anti-β₂GPI/β₂GPI-induced TF expression in THP-1 cells, and the effects of TLR-4 with ANX2 are tightly co-operative.
authors.affiliation: Department of Clinical Laboratory and Hematology, Jiangsu University, Zhenjiang, China. hongzhou@ujs.edu.cn
authors.forename: H
authors.initials: H
authors.lastname: Zhou
authors.forename: Y
authors.initials: Y
authors.lastname: Yan
authors.forename: G
authors.initials: G
authors.lastname: Xu
authors.forename: B
authors.initials: B
authors.lastname: Zhou
authors.forename: H
authors.initials: H
authors.lastname: Wen
authors.forename: D
authors.initials: D
authors.lastname: Guo
authors.forename: F
authors.initials: F
authors.lastname: Zhou
authors.forename: H
authors.initials: H
authors.lastname: Wang
mesh_terms: D017306:Annexin A2 / Q000378:metabolism; D017152:Antibodies, Antiphospholipid / Q000276:immunology*; D016736:Antiphospholipid Syndrome / Q000276:immunology*; D002460:Cell Line; D006801:Humans; D051218:Lymphocyte Antigen 96 / Q000378:metabolism; D009000:Monocytes / Q000187:drug effects / Q000276:immunology; D053594:Myeloid Differentiation Factor 88 / Q000378:metabolism; D017239:Paclitaxel / Q000494:pharmacology; D013925:Thromboplastin / Q000096:biosynthesis*; D051197:Toll-Like Receptor 4 / Q000378:metabolism*; D053482:beta 2-Glycoprotein I / Q000037:antagonists & inhibitors* / Q000276:immunology
chemical_list: D017306:Annexin A2; D017152:Antibodies, Antiphospholipid; C495377:LY96 protein, human; D051218:Lymphocyte Antigen 96; D053594:Myeloid Differentiation Factor 88; C495345:TLR4 protein, human; D051197:Toll-Like Receptor 4; D053482:beta 2-Glycoprotein I; D013925:Thromboplastin; D017239:Paclitaxel