Oxidative stress-induced protein radical formation precedes follicular dendritic cell apoptosis in murine sepsis (92.3)

Abstract

Abstract New studies indicate that most deaths from sepsis are actually the result of a substantially impaired immune response that is due to extensive death of immune effector cells including follicular dendritic cells (FDCs). However studies by Hotchkiss et al, and others have shown that FDC's undergo caspase 3-mediated apoptosis at 36 h post sepsis with profound depletion of these cells by 48 hours, but the underlying causes of apoptosis have been unknown. This study hypothesizes the role of oxidative stress-induced protein radical formation in FDCs as the principle cause of apoptosis in murine sepsis. This study utilizes immuno-spin trapping to detect DMPO (spin trap) nitrone adducts in FDCs isolated from Lipopolysaccharide (LPS)-primed mice after flow sorting. The isolated FDCs were also screened by LC/MS/MS analysis to detect possible proteins that contained DMPO nitrone adducts. Results indicated that mice administered LPS had DMPO nitrone adduct formation at 24 hours post sepsis as detected by western blot analysis and confocal microscopy. Mice administered allopurinol mice showed significant decrease in adduct formation, annexin V binding, thus indicating the role of xanthine oxidase in oxidative stress-induced protein radical formation and apoptosis. This clearly suggested a role of xanthine oxidase-mediated oxidative stress in FDC apoptosis in the germinal center of septic mice.