Interleukin-6 and mevastatin regulate plasminogen activator inhibitor-1 through CCAAT/enhancer-binding protein-δ

Objective - We sought to determine the etiologic mechanism of proinflammatory cytokine, interleukin-6 (IL-6), and statin as regulators of synthesis of plasminogen activator inhibitor-1 (PAI-1), the physiological fibrinolysis inhibitor and an acute-phase reactant. Methods and Results - Transient transfection and luciferase assay in HepG2 human hepatoma-derived cells demonstrated that IL-6 increased PAI-1 promoter activity and mevastatin decreased IL-6 - inducible response. Systematic deletion assay of the promoter demonstrated that the region ( - 239 to - 210 bp) containing a putative CCAAT/enhancer-binding protein (C/EBP) binding site was necessary. Point mutation in this site abolished the IL-6 - inducible response. Electrophoretic mobility shift assay and chromatin immunoprecipitation assay demonstrated that C/EBP alpha, C/EBP beta, and C/EBP delta were involved in protein - DNA complex formation in intact cells. Deoxyribonuclease ( DNase) I footprinting analysis revealed that 5' flanking region ( - 232 to - 210 bp) is acute-phase response protein-binding site. C/EBP delta binding activity was increased by IL-6 and attenuated by mevastatin. Mevastatin attenuated IL-6 - mediated increase of C/EBP delta protein in the nuclear extracts. IL-6 also increased PAI-1 and C/EBP delta mRNA in mouse primary hepatocytes. Conclusions - IL-6 increases hepatic PAI-1 expression mediated by the - 232- to - 210-bp region of the promoter containing a C/EBP delta binding site. Vascular protection by statins may be partly mediated through regulation of CEBP delta and consequent modulation of PAI-1 expression.