B. Friedrichs et al., Inhibition of tumor necrosis factor-alpha- and interleukin-1-induced endothelial E-selectin expression by thiol-modifying agents, ART THROM V, 18(12), 1998, pp. 1829-1837
The expression of endothelial-leukocyte adhesion molecules has been postula
ted to be regulated by redox-sensitive events. Tumor necrosis factor-alpha
(TNF-alpha)- and interleukin-1 (IL-1)-induced E-selectin expression was ana
lyzed after pretreating human umbilical vein endothelial cells with differe
nt thiol-modifying agents, ie, diamide, phenylarsine oxide, N-ethylmaleimid
e, and diethyl maleate. E-selectin protein expression was quantified by ind
irect immunofluorescence. All compounds suppressed the cytokine-induced E-s
electin expression in a concentration-dependent manner, whereas the antioxi
dant N-acetylcysteine showed no effect. The inhibitory effect of diamide (1
00 mu mol/L, 1 hour) was reversible within 6 hours when the cells were allo
wed to recover before application of cytokines. Reversibility was strongly
delayed when cells were deprived of glutathione by buthionine sulfoximine p
retreatment. 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. Monochlorobi
mane labeling also revealed a decrease in total cellular thiols. During rec
overy, the glutathione status was restored within 1 hour, whereas total thi
ol content and E-selectin expression needed at least 6 hours to return to b
aseline. Complete inhibition of E-selectin expression by the vicinal thiol
blocker phenylarsine oxide (0.5 mu mol/L) was reversed by dithiols like dit
hiothreitol or dimercaptopropanol, but not by the monothiol 2-mercaptoethan
ol. These data suggest that proteins with essential thiols, most probably v
icinal thiols. are involved in the IL-1- and TNF-alpha-mediated induction o
f E-selectin. These thiols must be in the reduced state; oxidation or other
modification thereof attenuates or abolishes the cells' response to the cy
tokines.