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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Figure 1

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PBEF is expressed in neutrophils and monocytes exposed to inflammatory s...
PBEF is expressed in neutrophils and monocytes exposed to inflammatory stimuli. (A) Neutrophils expressed mRNA transcripts for PBEF in response to LPS, TNF-α, and IL-1β, stimuli that inhibit neutrophil apoptosis. (B) LPS (1 ∝g/ml) induced transcripts for caspase-1 (open circles), reaching maximal concentrations by 1 hour, IL-1β (filled circles) peaking at 3 hours, and PBEF (filled triangles) reaching maximal levels at 10 hours. The mRNA expression was quantified by real-time PCR; data are expressed as fold increase over basal levels of expression for each mRNA species; n = 4. (C) Western blot analysis showed low-level expression of PBEF in control cells, while LPS (1 ∝g/ml) increased PBEF protein, with maximum expression evident 10 hours after exposure. Blots were reprobed with β-actin to confirm equal loading; data are representative of three separate experiments. (D) PBEF mRNA transcripts were also expressed in peripheral blood monocytes, but not lymphocytes, in response to LPS, TNF, and IL-1. Blots are representative of three separate experiments; corresponding mRNA for GAPDH is shown to evaluate sample loading. (E) HL-60 cells induced to granulocytic differentiation by 1 ∝M all-trans retinoic acid showed increased message for PBEF, and transcript levels evaluated by real-time PCR were further increased by exposure of differentiated HL-60 cells to LPS (1 ∝g/ml) added to cultures with all-trans retinoic acid at day 0. Data are normalized to levels of PBEF transcripts in undifferentiated HL-60 cells; *P < 0.05 versus all-trans retinoic acid alone; n = 4. ATRA, all-trans retinoic acid.