WAVE1 mediates suppression of phagocytosis by phospholipid-derived DAMPs
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
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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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 6

OxPL in human PDF inhibit phagocytosis in the presence of WAVE1.

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OxPL in human PDF inhibit phagocytosis in the presence of WAVE1. (A) Lev...
(A) Levels of oxidized phosphocholine were measured using the EO6 mAb or an isotype control in PDF from 2 patients undergoing peritoneal dialysis. (B) Murine primary peritoneal macrophages were incubated for 15 minutes with PDF of 1 representative patient (patient A), and phagocytosis of E. coli after 60 minutes was assessed by FACS. Ig depletion was done with protein G beads. (C) PLF from Ldlr–/–Rag–/– mice on normal diet (ND) or high-fat diet (HFD) was placed on primary peritoneal macrophages in the presence or absence of Ht-31 (100 μM) and phagocytosis of E. coli after 60 minutes. (D) RAW 264.7 macrophages were either preincubated with EO6 antibody or isotype control (1 μg/ml) for 1 hour, then with OxPL or DMPC (5 μg/ml) for 15 minutes. Phagocytosis of E. coli was assessed after 60 minutes by FACS. Control assays were done in RPMI. (E) PDF of patient A was subjected to chloroform extraction, and the resultant water or lipid fraction was added to RAW 264.7 cells 15 minutes prior to addition of E. coli. Phagocytosis was assayed after 60 minutes by FACS. Control assays were done in RPMI. (F) RAW 264.7 macrophages were incubated for 15 minutes with IgG-depleted PDF that had been pretreated with either EO6 or isotype control antibody (10 μg/ml) for 1 hour, and phagocytosis of E. coli after 60 minutes was assessed by FACS. (G) WT and Wave1–/– primary peritoneal macrophages were incubated with Ig-depleted PDF from patient A, and phagocytosis of E. coli was determined was analyzed. Data are mean ± SEM of at least duplicate experiments; *P < 0.05; **P < 0.01; ***P < 0.001 versus corresponding control.