sEH promotes macrophage phagocytosis and lung clearance of Streptococcus pneumoniae
Hong Li, J. Alyce Bradbury, Matthew L. Edin, Joan P. Graves, Artiom Gruzdev, Jennifer Cheng, Samantha L. Hoopes, Laura M. DeGraff, Michael B. Fessler, Stavros Garantziotis, Shepherd H. Schurman, Darryl C. Zeldin
Hong Li, J. Alyce Bradbury, Matthew L. Edin, Joan P. Graves, Artiom Gruzdev, Jennifer Cheng, Samantha L. Hoopes, Laura M. DeGraff, Michael B. Fessler, Stavros Garantziotis, Shepherd H. Schurman, Darryl C. Zeldin
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Research Article Cell biology Infectious disease

sEH promotes macrophage phagocytosis and lung clearance of Streptococcus pneumoniae

Abstract

Epoxyeicosatrienoic acids (EETs) have potent antiinflammatory properties. Hydrolysis of EETs by soluble epoxide hydrolase/ epoxide hydrolase 2 (sEH/EPHX2) to less active diols attenuates their antiinflammatory effects. Macrophage activation is critical to many inflammatory responses; however, the role of EETs and sEH in regulating macrophage function remains unknown. Lung bacterial clearance of Streptococcus pneumoniae was impaired in Ephx2-deficient (Ephx2–/–) mice and in mice treated with an sEH inhibitor. The EET receptor antagonist EEZE restored lung clearance of S. pneumoniae in Ephx2–/– mice. Ephx2–/– mice had normal lung Il1b, Il6, and Tnfa expression levels and macrophage recruitment to the lungs during S. pneumoniae infection; however, Ephx2 disruption attenuated proinflammatory cytokine induction, Tlr2 and Pgylrp1 receptor upregulation, and Ras-related C3 botulinum toxin substrates 1 and 2 (Rac1/2) and cell division control protein 42 homolog (Cdc42) activation in PGN-stimulated macrophages. Consistent with these observations, Ephx2–/– macrophages displayed reduced phagocytosis of S. pneumoniae in vivo and in vitro. Heterologous overexpression of TLR2 and peptidoglycan recognition protein 1 (PGLYRP1) in Ephx2–/– macrophages restored macrophage activation and phagocytosis. Human macrophage function was similarly regulated by EETs. Together, these results demonstrate that EETs reduced macrophage activation and phagocytosis of S. pneumoniae through the downregulation of TLR2 and PGLYRP1 expression. Defining the role of EETs and sEH in macrophage function may lead to the development of new therapeutic approaches for bacterial diseases.

Authors

Hong Li, J. Alyce Bradbury, Matthew L. Edin, Joan P. Graves, Artiom Gruzdev, Jennifer Cheng, Samantha L. Hoopes, Laura M. DeGraff, Michael B. Fessler, Stavros Garantziotis, Shepherd H. Schurman, Darryl C. Zeldin

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Figure 2

S. pneumoniae lung clearance is impaired early during infection in Ephx2–/– mice and altered by pharmacological sEH inhibition or EET antagonism in vivo.

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S. pneumoniae lung clearance is impaired early during infection in Ephx...
(A) WT and Ephx2–/– mice (n = 5–10 per group) were inoculated by intranasal aspiration with either saline (PBS, negative control) or S. pneumonia at 2 × 105 CFU/mouse. Colony counts were determined by serial dilution assay in lungs collected 12 hours after inoculation. (B) Bronchoalveolar lavage was performed on the mice in A, and total BALF cells and cell differentials were determined. (C) Levels of Il-1β, IL-6, and TNF-α protein in BALF from mice in A were determined by multiplex array. (D) WT mice (n = 14–56 per group) were treated with either vehicle (1% PEG400) or 1% PEG400 containing 10 mg/L TPPU in the drinking water and inoculated by intranasal aspiration with either saline (negative control) or S. pneumonia at 2 × 105 CFU/mouse. Colony counts were determined by serial dilution assay in lungs removed 48 hours after inoculation. Data represent the mean ± SEM of 4 independent experiments. *P < 0.05. (E) WT and Ephx2–/– mice (n = 5–10 per group) were dosed with vehicle or EEZE (15 μg/kg/day) via Alzet minipumps and inoculated with either saline (negative control) or S. pneumonia at 2 × 105 CFU/mouse. Colony counts were determined in lungs removed 48 hours after inoculation. *P < 0.05, by ordinary 2-way ANOVA, followed by Tukey’s post hoc multiple-comparison test (A–E).