Caspase-8 is activated by cathepsin D initiating neutrophil apoptosis during the resolution of inflammation

S Conus, R Perozzo, T Reinheckel, C Peters… - The Journal of …, 2008 - rupress.org
S Conus, R Perozzo, T Reinheckel, C Peters, L Scapozza, S Yousefi, HU Simon
The Journal of experimental medicine, 2008rupress.org
In the resolution of inflammatory responses, neutrophils rapidly undergo apoptosis. We
describe a new proapoptotic pathway in which cathepsin D directly activates caspase-8.
Cathepsin D is released from azurophilic granules in neutrophils in a caspase-independent
but reactive oxygen species–dependent manner. Under inflammatory conditions, the
translocation of cathepsin D in the cytosol is blocked. Pharmacological or genetic inhibition
of cathepsin D resulted in delayed caspase activation and reduced neutrophil apoptosis …
In the resolution of inflammatory responses, neutrophils rapidly undergo apoptosis. We describe a new proapoptotic pathway in which cathepsin D directly activates caspase-8. Cathepsin D is released from azurophilic granules in neutrophils in a caspase-independent but reactive oxygen species–dependent manner. Under inflammatory conditions, the translocation of cathepsin D in the cytosol is blocked. Pharmacological or genetic inhibition of cathepsin D resulted in delayed caspase activation and reduced neutrophil apoptosis. Cathepsin D deficiency or lack of its translocation in the cytosol prolongs innate immune responses in experimental bacterial infection and in septic shock. Thus, we identified a new function of azurophilic granules that is in addition to their role in bacterial defense mechanisms: to regulate the life span of neutrophils and, therefore, the duration of innate immune responses through the release of cathepsin D.
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