Secreted phospholipase PLA2G5 acts as a hemolytic factor in sepsis
Michihiro Takahama, Krysta S. Wolfe, Gabriella Richey, Madison Plaster, Anna Czapar, Fabian Hernandez, Denis Cipurko, Tatsuki Ueda, Yoshimi Miki, Yuki Nagasaki, Yoshitaka Taketomi, Tatsuya Saitoh, Tadafumi Kawamoto, Steven M. Dudek, Makoto Murakami, Nicolas Chevrier
Michihiro Takahama, Krysta S. Wolfe, Gabriella Richey, Madison Plaster, Anna Czapar, Fabian Hernandez, Denis Cipurko, Tatsuki Ueda, Yoshimi Miki, Yuki Nagasaki, Yoshitaka Taketomi, Tatsuya Saitoh, Tadafumi Kawamoto, Steven M. Dudek, Makoto Murakami, Nicolas Chevrier
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Research Article Infectious disease Inflammation

Secreted phospholipase PLA2G5 acts as a hemolytic factor in sepsis

Abstract

Sepsis is a systemic response to infection with life-threatening consequences such as hemolysis, a predictor of mortality risks for the disease. Here, by measuring organism-wide changes in gene expression, we discovered that the secreted phospholipase PLA2G5 is induced in colon cell types during sepsis. The genetic deletion of Pla2g5 and treatment with a PLA2G5 antibody were both associated with protection from lethal sepsis. Treatment with a PLA2G5 antibody during sepsis was associated with increased splenic red pulp macrophages and improved iron homeostasis, linking PLA2G5 to red blood cell homeostasis during sepsis. Mechanistically, bloodborne PLA2G5 led to intravascular hemolysis through its lipolytic activity on red blood cell membranes. In humans with sepsis due to bacterial, fungal, or viral infections, the serum level of PLA2G5 was elevated and predictive of disease severity and mortality. We conclude that sepsis corrupts PLA2G5 into becoming an intravascular hemolytic factor which is toxic for host red blood cells.

Authors

Michihiro Takahama, Krysta S. Wolfe, Gabriella Richey, Madison Plaster, Anna Czapar, Fabian Hernandez, Denis Cipurko, Tatsuki Ueda, Yoshimi Miki, Yuki Nagasaki, Yoshitaka Taketomi, Tatsuya Saitoh, Tadafumi Kawamoto, Steven M. Dudek, Makoto Murakami, Nicolas Chevrier

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Figure 5

PLA2G5 lyses erythrocyte membrane phospholipids in vitro, leading to hemolysis.

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PLA2G5 lyses erythrocyte membrane phospholipids in vitro, leading to hem...
(A–E) In vitro hemolysis assay. Shown are percentages of cell-free oxyhemoglobin (relative to an equal volume of chemically lysed erythrocytes) in cell lysates from normal (control) or phosphatidylserine-exposing (PS-exposing; damaged) erythrocytes incubated with recombinant human PLA2G5 (rPLA2G5) or BSA for 1 hour at 37°C (A), PS-exposing erythrocytes incubated with indicated concentrations of rPLA2G5 for 1 hour at 37°C (B), PS-exposing erythrocytes incubated with rPLA2G5 in the presence or absence of the secreted phospholipase A2 inhibitor Varespladib or left untreated (control) (C), PS-exposing erythrocytes incubated with purified C-terminally His-tagged recombinant mouse PLA2G5 (rmPLA2G5) in the presence of PLA2G5 or isotype control IgG antibodies (D), or PS-exposing erythrocytes incubated with rPLA2G5 in isotonic, hypotonic, or hypertonic solution (E). Means ± SEM are shown (n = 4–5). Data are representative of 3 independent experiments. (F and G) Lipidomics profiling of normal or PS-exposing erythrocytes incubated with rPLA2G5 for 1 hour at 37°C. Shown are fold changes relative to normal erythrocytes (F) and mass spectrometry intensities (G) for indicated lipid metabolites. LPA, lysophosphatidic acid; LPC, lysophosphatidylcholine; LPE, lysophosphatidylethanolamine; LPG, lysophosphatidylglycerol; LPI, lysophosphatidylinositol; OA, oleic acid; LA, linoleic acid; AA, arachidonic acid; EPA, eicosapentaenoic acid; DHA, docosahexaenoic acid. Means ± SEM are shown (n = 3). *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001 by 1-way ANOVA with Tukey-Kramer test.