Augmented intracellular glutathione inhibits Fas-triggered apoptosis of
activated human neutrophils
RW Watson, OD Rotstein, M Jimenez, J Parodo and JC Marshall
Department of Surgery, The Toronto Hospital, University of Toronto, Canada.
Agonist signals delivered through cell surface Fas induce apoptosis.
However, the apoptotic program can be modulated by signals from the
environment, and in particular, by signals delivered through adhesion
molecules. Because neutrophil functional activity in inflammation is
contingent on cell survival, and because circulating neutrophils normally
die rapidly through a constitutively expressed apoptotic program, we
evaluated Fas-mediated apoptosis in resting and inflammatory human
neutrophils. We show that normal neutrophils respond to Fas engagement with
accelerated rates of apoptosis, but cross- linking of beta2 integrins or
priming with bacterial lipopolysaccharide (LPS) prevents this increase.
Adhesion molecule cross-linking results in increased intracellular
glutathione (GSH). Augmentation of intracellular GSH with exogenous GSH or
N-acetylcysteine is sufficient to reduce the Fas-triggered increase in
apoptotic rates. Prevention of the activation induced GSH increase by
buthionine sulfoximine, a cell permeable inhibitor of GSH biosynthesis,
restored Fas responsiveness in activated neutrophils, an effect that could
be blocked with exogenous GSH. Taken together, these data show that
Fas-induced signaling for neutrophil apoptosis is blocked in a redox
sensitive manner by costimulatory signals delivered through beta2 integrins
or activation by LPS, and provide a biologic explanation for sustained
neutrophil survival in the inflammatory environment.
Volume 89,
Issue 11,
pp. 4175-4181,
06/01/1997
Copyright © 1997 by The American Society of Hematology
