WAVE1 mediates suppression of phagocytosis by phospholipid-derived DAMPs
Ulrich Matt, … , John D. Scott, Sylvia Knapp
Ulrich Matt, … , John D. Scott, Sylvia Knapp
Published June 24, 2013
Citation Information: J Clin Invest. 2013;123(7):3014-3024. https://doi.org/10.1172/JCI60681.
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Research Article Immunology

WAVE1 mediates suppression of phagocytosis by phospholipid-derived DAMPs

Abstract

Clearance of invading pathogens is essential to preventing overwhelming inflammation and sepsis that are symptomatic of bacterial peritonitis. Macrophages participate in this innate immune response by engulfing and digesting pathogens, a process called phagocytosis. Oxidized phospholipids (OxPL) are danger-associated molecular patterns (DAMPs) generated in response to infection that can prevent the phagocytic clearance of bacteria. We investigated the mechanism underlying OxPL action in macrophages. Exposure to OxPL induced alterations in actin polymerization, resulting in spreading of peritoneal macrophages and diminished uptake of E. coli. Pharmacological and cell-based studies showed that an anchored pool of PKA mediates the effects of OxPL. Gene silencing approaches identified the A-kinase anchoring protein (AKAP) WAVE1 as an effector of OxPL action in vitro. Chimeric Wave1–/– mice survived significantly longer after infection with E. coli and OxPL treatment in vivo. Moreover, we found that endogenously generated OxPL in human peritoneal dialysis fluid from end-stage renal failure patients inhibited phagocytosis via WAVE1. Collectively, these data uncover an unanticipated role for WAVE1 as a critical modulator of the innate immune response to severe bacterial infections.

Authors

Ulrich Matt, Omar Sharif, Rui Martins, Tanja Furtner, Lorene Langeberg, Riem Gawish, Immanuel Elbau, Ana Zivkovic, Karin Lakovits, Olga Oskolkova, Bianca Doninger, Andreas Vychytil, Thomas Perkmann, Gernot Schabbauer, Christoph J. Binder, Valery N. Bochkov, John D. Scott, Sylvia Knapp

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Figure 4

The AKAP WAVE1 mediates OxPL inhibition of phagocytosis in peritoneal macrophages.

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The AKAP WAVE1 mediates OxPL inhibition of phagocytosis in peritoneal ma...
AKAP-Lbc (150 bp), Wave1 (116 bp), and Gravin (136 bp) mRNA expression in (A) RAW 264.7 or (B) primary peritoneal macrophages; GAPDH (372 bp). (C) Western blot verifying silencing of Wave1 (82 kD) in RAW 264.7 cells; β-actin control (37 kD). (D) Scrambled control and shRNA (targeting Wave1) cells incubated with carrier, DMPC, or OxPAPC (10 μg/ml) and stained with phalloidin (green) and PI for nuclei (red). Original magnification, ×800. (E) Phagocytosis of E. coli (60 minutes) assayed in scrambled control and shRNA-Wave1 cells preincubated with carrier, DMPC, or OxPAPC (5 μg/ml). Data depicted are mean ± SEM of triplicates, *P < 0.05 versus corresponding carrier/DMPC. (F) mRNA expression and (G) Western blot for Wave1 in WT and Wave1–/– primary peritoneal macrophages (WAVE1 82 kD; β-actin 39 kD). (H) Primary peritoneal macrophages of WT and Wave1–/– mice incubated with carrier, DMPC, or OxPAPC (10 μg/ml) and stained with phalloidin (green) and PI (red). (I) Phagocytosis of FITC-labeled E. coli (60 minutes) by WT and Wave1–/– peritoneal macrophages analyzed after prior incubation with DMPC or OxPAPC (5 μg/ml). Data are mean ± SEM of triplicates of 2 independent experiments; **P < 0.01 versus corresponding DMPC.