A novel class of antioxidants inhibit LPS induction of tissue factor by selective inhibition of the activation of ASK1 and MAP kinases.

OBJECTIVE: Oxidative stress contributes to the pathogenesis of many diseases, including atherosclerosis and sepsis. We have previously described a novel class of therapeutic compounds with antioxidant and antiinflammatory properties. However, at present, the intracellular targets of these compounds have not been identified. The purpose of this study was to elucidate the mechanism by which 2 structurally-related antioxidants (AGI-1067 and AGI-1095) inhibit LPS induction of tissue factor (TF) expression in human monocytic cells and endothelial cells. METHODS AND RESULTS: We found that succinobucol (AGI-1067) and AGI-1095 inhibited LPS induction of TF expression in both monocytic cells and endothelial cells. These compounds also reduced LPS induction of nuclear AP-1 and expression of Egr-1 without affecting nuclear translocation of NF-kappaB. Importantly, these antioxidants inhibited LPS activation of the redox-sensitive kinase, apoptosis signal-regulating kinase-1 (ASK1) and the mitogen-activated protein kinases (MAPKs) p38, ERK1/2, and JNK1/2. CONCLUSIONS: AGI-1067 and AGI-1095 inhibit TF gene expression in both monocytic cells and endothelial cells through a mechanism that involves the inhibition of the redox-sensitive MAP3K, ASK1. These compounds selectively reduce the activation/induction of MAPK, AP-1, and Egr-1 without affecting NF-kappaB nuclear translocation.

AGIX-4207 [2-[4-[[1-[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]thio]-1-methylethyl]thio]-2,6-bis(1,1-dimethylethyl)phenoxy]acetic acid], a novel antioxidant and anti-inflammatory compound: cellular and biochemical characterization of antioxidant activity and inhibition of redox-sensitive inflammatory gene expression.

The pathogenesis of chronic inflammatory diseases, including rheumatoid arthritis, is regulated, at least in part, by modulation of oxidation-reduction (redox) homeostasis and the expression of redox-sensitive inflammatory genes including adhesion molecules, chemokines, and cytokines. AGIX-4207 [2-[4-[[1-[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]thio]-1-methylethyl]thio]-2,6-bis(1,1-dimethylethyl)phenoxy]acetic acid] is a novel, orally active, phenolic antioxidant and anti-inflammatory compound with antirheumatic properties. To elucidate its anti-inflammatory mechanisms, we evaluated AGIX-4207 for a variety of cellular, biochemical, and molecular properties. AGIX-4207 exhibited potent antioxidant activity toward lipid peroxides in vitro and displayed enhanced cellular uptake relative to a structurally related drug, probucol. This resulted in potent inhibition of cellular levels of reactive oxygen species in multiple cell types. AGIX-4207 selectively inhibited tumor necrosis factor (TNF)-alpha-inducible levels of the redox-sensitive genes, vascular cell adhesion molecule-1 and monocyte chemoattractant protein-1, with less inhibition of E-selectin, and no effect on intracellular adhesion molecule-1 expression in endothelial cells. In addition, AGIX-4207 inhibited cytokine-induced levels of monocyte chemoattractant protein-1, interleukin (IL)-6, and IL-8 from endothelial cells and human fibroblast-like synoviocytes as well as lipopolysaccharide-induced release of TNF-alpha, IL-1beta, and IL-6 from human peripheral blood mononuclear cells. AGIX-4207 did not inhibit TNF-alpha-induced nuclear translocation of nuclear factor of the kappa-enhancer in B cells (NF-kappaB), suggesting that the mechanism of action is independent of this redox-sensitive transcription factor. Taken together, these results provide a mechanistic framework for understanding the anti-inflammatory and antirheumatic activity of AGIX-4207 and provide further support for the view that inhibition of redox-sensitive inflammatory gene expression is an attractive approach for the treatment of chronic inflammatory diseases.