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 3

OxPL-induced inhibition of phagocytosis requires anchoring of PKA in vivo and in vitro.

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OxPL-induced inhibition of phagocytosis requires anchoring of PKA in viv...
(A) RAW 264.7 cells were incubated with carrier, DMPC, or OxPAPC (10 μg/ml) alone or after treatment with 100 μM Ht-31 (30 minutes) and stained with phalloidin (green) and PI (red). Original magnification, ×800. (B) RAW 264.7 cells were treated with carrier or phospholipids (5 μg/ml; 15 minutes) alone or after preincubation with Ht-31 (100 μM) for 30 minutes. Phagocytosis of FITC-labeled E. coli was analyzed using FACS after 60 minutes. Uptake is expressed relative to carrier. **P < 0.01. Data show mean ± SEM of triplicates and are representative of 3 independent experiments. (C) Mice received carrier or 2.5 mg/kg OxPAPC i.p. and/or 100 μM of Ht-31 immediately before infection with 104 CFU E. coli. At 10 hours after infection, PLF was harvested and bacterial CFUs enumerated. Data are mean ± SEM of 2 independent experiments from n = 7–9 mice/group; **P < 0.01 versus carrier. (D) Mice received 2.5 mg/kg DMPC or OxPAPC i.p. followed by i.p. injection of vehicle or Ht-31 (OxPAPC–Ht-31), after which they were infected with 104 CFU E. coli. Survival was monitored every 2 hours; n = 12 mice/group. P values indicate differences between OxPAPC versus DMPC or OxPAPC versus OxPAPC-Ht-31, respectively.