Inhibition of Tumor Necrosis Factor-α– and Interleukin-1–Induced Endothelial E-Selectin Expression by Thiol-Modifying Agents

Abstract

Abstract-The expression of endothelial-leukocyte adhesion molecules has been postulated to be regulated by redoxsensitive events. Tumor necrosis factor-␣ (TNF-␣)-and interleukin-1 (IL-1)-induced E-selectin expression was analyzed after pretreating human umbilical vein endothelial cells with different thiol-modifying agents, ie, diamide, phenylarsine oxide, N-ethylmaleimide, and diethyl maleate. E-selectin protein expression was quantified by indirect immunofluorescence. All compounds suppressed the cytokine-induced E-selectin expression in a concentrationdependent manner, whereas the antioxidant N-acetylcysteine showed no effect. The inhibitory effect of diamide (100 mol/L, 1 hour) was reversible within 6 hours when the cells were allowed to recover before application of cytokines. Reversibility was strongly delayed when cells were deprived of glutathione by buthionine sulfoximine pretreatment. Glutathione depletion alone did not influence cytokine-induced E-selectin expression. Analysis of cellular glutathione status showed a 3-fold increase in oxidized glutathione after diamide treatment. Monochlorobimane labeling also revealed a decrease in total cellular thiols. During recovery, the glutathione status was restored within 1 hour, whereas total thiol content and E-selectin expression needed at least 6 hours to return to baseline. Complete inhibition of E-selectin expression by the vicinal thiol blocker phenylarsine oxide (0.5 mol/L) was reversed by dithiols like dithiothreitol or dimercaptopropanol, but not by the monothiol 2-mercaptoethanol. These data suggest that proteins with essential thiols, most probably vicinal thiols. are involved in the IL-1-and TNF-␣-mediated induction of E-selectin. These thiols must be in the reduced state; oxidation or other modification thereof attenuates or abolishes the cells' response to the cytokines.

Endothelial preconditioning by transient oxidative stress reduces inflammatory responses of cultured endothelial cells to TNF‐α

“…5), i.e., the time, when NF B translocation was measured. Despite the absence of differences in global redox status between these two groups, it cannot be excluded that the redox state of specific thiols, which modulate TNF-␣ effects (17), might have been affected for this duration. A partial explanation of the anti-inflammatory actions of brief oxidative stress could be that NF B down-regulates its own expression via a negative feedback loop (37).…”

“…Oxidative stress has been shown to occur during preconditioning (13) and to be mandatory for the success of preconditioning in some models (14,15). This also seemed of broader interest because the modulation of cellular redox status has recently turned out to be a major signal for inflammatory reactions (16,17).…”

The Molecular Basis for the Pharmacokinetics and Pharmacodynamics of Curcumin and Its Metabolites in Relation to Cancer

“…When the free thiol groups of IRAK were occupied by iodo-acetyl-[ 125 I]iodotyrosine in IL-1-stimulated cells, curcumin blocked the extent of radiolabeling in a concentration-dependent manner, indicating thiol modification by curcumin. Inasmuch as the inhibition of IRAK thiols by, e.g., phenylarsine oxide, is reversible in the presence of thiol reductants such as dithiothreitol and dimercaptopropanol (Singh and Aggarwal, 1995;Friedrichs et al, 1998) but irreversible in case of curcumin, the thiol modification by curcumin does not entail a redox reaction but most likely a covalent Michael addition-mediated alkylation (DinkovaKostova and Talalay, 1999;Jurrmann et al, 2005).…”

Thioredoxin Facilitates the Induction of Heme Oxygenase-1 in Response to Inflammatory Mediators

“…These transcription factors are responsible for the up-regulation of a battery of genes involved in the inflammatory response. These include genes encoding adhesion molecules, matrix metalloproteinases, and inflammatory cytokines (13,14).…”