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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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 1

Oxidation of lipids occurs in E. coli peritonitis in vivo and leads to an actin-dependent change in cell shape in vitro.

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Oxidation of lipids occurs in E. coli peritonitis in vivo and leads to a...
(A) Endogenous levels of oxidized phosphatidylcholine were measured in PLF of mice infected with E. coli after 8 or 16 hours, respectively, compared with supernatants of RAW 264.7 cells after adding 5 or 10 μg/ml of OxPAPC, respectively. Co, control. (B) RAW 267.4 cells were incubated with indicated doses of OxPAPC or DMPC for 15 minutes, and phagocytosis of E. coli was assessed after 60 and 120 minutes (triplicates, representative of 3 independent experiments). (C) FACS histogram showing uptake of FITC-labeled E. coli by resident peritoneal macrophages pretreated with 10 μg/ml of OxPAPC or DMPC after 60 minutes. (D) Mice (n = 8/group) were infected with 104 CFU E. coli i.p. and treated with 2.5 mg/kg DMPC or OxPAPC i.p. Peritoneal CFU counts were enumerated 10 hours after infection. Data (A–D) are presented as mean ± SEM; *P < 0.05; **P < 0.01 versus controls. ***P < 0.001. (E) RAW 264.7 cells were incubated with carrier, DMPC, or OxPAPC (10 μg/ml; 30 minutes) alone or following incubation with 2 μM cytochalasin D (30 minutes). Cells were subsequently stained for F-actin using phalloidin (green) and PI for nuclei (red). Scale bar: 30 μm.