Pre–B cell colony–enhancing factor inhibits neutrophil apoptosis in experimental inflammation and clinical sepsis
Song Hui Jia, … , Ori D. Rotstein, John C. Marshall
Song Hui Jia, … , Ori D. Rotstein, John C. Marshall
Published May 1, 2004
Citation Information: J Clin Invest. 2004;113(9):1318-1327. https://doi.org/10.1172/JCI19930.
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Article Infectious disease

Pre–B cell colony–enhancing factor inhibits neutrophil apoptosis in experimental inflammation and clinical sepsis

Abstract

Pre–B cell colony-enhancing factor (PBEF) is a highly conserved 52-kDa protein, originally identified as a growth factor for early stage B cells. We show here that PBEF is also upregulated in neutrophils by IL-1β and functions as a novel inhibitor of apoptosis in response to a variety of inflammatory stimuli. Induction of PBEF occurs 5–10 hours after LPS exposure. Prevention of PBEF translation with an antisense oligonucleotide completely abrogates the inhibitory effects of LPS, IL-1, GM-CSF, IL-8, and TNF-α on neutrophil apoptosis. Immunoreactive PBEF is detectable in culture supernatants from LPS-stimulated neutrophils, and a recombinant PBEF fusion protein inhibits neutrophil apoptosis. PBEF is also expressed in neutrophils from critically ill patients with sepsis in whom rates of apoptosis are profoundly delayed. Expression occurs at higher levels than those seen in experimental inflammation, and a PBEF antisense oligonucleotide significantly restores the normal kinetics of apoptosis in septic polymorphonuclear neutrophils. Inhibition of apoptosis by PBEF is associated with reduced activity of caspases-8 and -3, but not caspase-9. These data identify PBEF as a novel inflammatory cytokine that plays a requisite role in the delayed neutrophil apoptosis of clinical and experimental sepsis.

Authors

Song Hui Jia, Yue Li, Jean Parodo, Andras Kapus, Lingzhi Fan, Ori D. Rotstein, John C. Marshall

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PBEF inhibits the cleavage and catalytic activity of caspase-3 and block...
PBEF inhibits the cleavage and catalytic activity of caspase-3 and blocks the activity of caspase-8. (A) Caspase-3 is cleaved to yield active 18- to 20-kDa fragments in constitutively apoptotic neutrophils; LPS inhibits the activational cleavage of this effector caspase, as evaluated by Western blot analysis following 6 hours of in vitro culture. PBEF antisense prevented the inhibitory effects of LPS, while the sense control did not. Blot shown is representative of three separate studies. (B) Caspase-3 activity, measured colorimetrically in arbitrary units as the cleavage of the tetrapeptide Ac-DEVD-pNA was also reduced in neutrophils following exposure to LPS; PBEF antisense, but not the sense control, prevented this reduction in caspase-3 activity. Results are means ± SD of six separate studies; *P < 0.05 versus control levels or activity levels in neutrophils treated with PBEF antisense. (C) Cleavage of pro_caspase-3 to active caspase-3 (20 kDa) was reduced in neutrophils incubated with LPS (1 μg/ml) or rPBEF (50 ng/ml); Western blot is representative of 3 separate experiments. (D) Caspase-8 activity, measured colorimetrically in arbitrary units as the cleavage of the caspase-8 tetrapeptide target Ac-IETD-pNA was reduced by exposure to LPS and restored by pretreatment of neutrophils with PBEF antisense. Results are means ± SD of six separate studies; *P < 0.05, control or sense-treated cells versus antisense-treated neutrophils or neutrophils cultured in the absence of LPS. (E) Cleavage of pro_caspase-8 (53 kDa) to its active form (18 kDa) was also inhibited by exposure of neutrophils to LPS or rPBEF; Western blot is representative of 3 separate experiments.