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Eosinophil lipid bodies: specific, inducible intracellular sites for enhanced eicosanoid formation.

Bozza PT, Yu W, Penrose JF, Morgan ES, Dvorak AM, Weller PF - J. Exp. Med. (1997)

Bottom Line: The specific intracellular sites at which enzymes act to generate arachidonate-derived eicosanoid mediators of inflammation are uncertain.We evaluated the formation and function of cytoplasmic lipid bodies.Thus, lipid bodies are structurally distinct, inducible, nonnuclear sites for enhanced synthesis of paracrine eicosanoid mediators of inflammation.

View Article: PubMed Central - PubMed

Affiliation: Harvard Thorndike Laboratory and Charles A. Dana Research Institute, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02115, USA.

ABSTRACT
The specific intracellular sites at which enzymes act to generate arachidonate-derived eicosanoid mediators of inflammation are uncertain. We evaluated the formation and function of cytoplasmic lipid bodies. Lipid body formation in eosinophils was a rapidly (<1 h) inducible response which was platelet-activating factor (PAF) receptor-mediated, involved signaling through protein kinase C, and required new protein synthesis. In intact and enucleated eosinophils, the PAF-induced increases in lipid body numbers correlated with enhanced production of both lipoxygenase- and cyclooxygenase-derived eicosanoids. All principal eosinophil eicosanoid-forming enzymes, 5-lipoxygenase, leukotriene C4 synthase, and cyclooxygenase, were immunolocalized to native as well as newly induced lipid bodies in intact and enucleated eosinophils. Thus, lipid bodies are structurally distinct, inducible, nonnuclear sites for enhanced synthesis of paracrine eicosanoid mediators of inflammation.

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PAF receptor–mediated induction of lipid body  formation in eosinophils. (A)  Human eosinophils, at a concentration of 106 cells/ml, were  treated with PAF (10−8–10−6M)  (white squares) or lyso-PAF (10−8– 10−6 M) (black squares) for 1 h at  37°C. (B) Human eosinophils at  a concentration of 106 cells/ml  were pretreated with WEB 2086  (10–100 μM), pertussis toxin  (100 ng/ml), or vehicle for 1 h at  37°C. The cells were then  treated with PAF (1 μM) or vehicle for 1 h at 37°C. Lipid bodies were enumerated using light  microscopy after osmium staining. Each point represents the  mean ± SEM of lipid bodies on 50 consecutive eosinophils from three to five independent assays using different donors. *Statistically significant difference between PAF and the vehicle. +Statistically significant differences caused by pretreatment with WEB 2086 or pertussis toxin.
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Figure 1: PAF receptor–mediated induction of lipid body formation in eosinophils. (A) Human eosinophils, at a concentration of 106 cells/ml, were treated with PAF (10−8–10−6M) (white squares) or lyso-PAF (10−8– 10−6 M) (black squares) for 1 h at 37°C. (B) Human eosinophils at a concentration of 106 cells/ml were pretreated with WEB 2086 (10–100 μM), pertussis toxin (100 ng/ml), or vehicle for 1 h at 37°C. The cells were then treated with PAF (1 μM) or vehicle for 1 h at 37°C. Lipid bodies were enumerated using light microscopy after osmium staining. Each point represents the mean ± SEM of lipid bodies on 50 consecutive eosinophils from three to five independent assays using different donors. *Statistically significant difference between PAF and the vehicle. +Statistically significant differences caused by pretreatment with WEB 2086 or pertussis toxin.

Mentions: Lipid bodies, although small in number, are normal constituents of leukocytes, including eosinophils. Increased lipid body formation occurs in vivo and can be induced in vitro. In eosinophils obtained from normal donors, within 1 h PAF stimulated a dose-dependent induction of lipid body formation in vitro (Fig. 1 A). In response to 1 μM PAF, lipid body numbers persisted at similar numbers at 1, 4, and 8 h (14.1 ± 0.5, 15.9 ± 0.7, and 9.5 ± 0.5 lipid bodies ± SEM/eosinophil, respectively) with no evidence of enhanced cell death or apoptosis (<7% apoptotic eosinophils at 8 h with and without PAF stimulation). Several findings indicated that the actions of PAF were receptor mediated. First, lyso-PAF failed to induce lipid body formation (Fig. 1 A). Second, the PAF-receptor antagonist WEB 2086 dose-dependently inhibited PAF- induced lipid body formation (Fig. 1 B). Moreover, earlier treatment of cells with pertussis toxin (100 ng/ml, 1 h before PAF) to block PAF-receptor G-protein–mediated signals completely prevented PAF-induced lipid body formation in human eosinophils (Fig. 1 B).


Eosinophil lipid bodies: specific, inducible intracellular sites for enhanced eicosanoid formation.

Bozza PT, Yu W, Penrose JF, Morgan ES, Dvorak AM, Weller PF - J. Exp. Med. (1997)

PAF receptor–mediated induction of lipid body  formation in eosinophils. (A)  Human eosinophils, at a concentration of 106 cells/ml, were  treated with PAF (10−8–10−6M)  (white squares) or lyso-PAF (10−8– 10−6 M) (black squares) for 1 h at  37°C. (B) Human eosinophils at  a concentration of 106 cells/ml  were pretreated with WEB 2086  (10–100 μM), pertussis toxin  (100 ng/ml), or vehicle for 1 h at  37°C. The cells were then  treated with PAF (1 μM) or vehicle for 1 h at 37°C. Lipid bodies were enumerated using light  microscopy after osmium staining. Each point represents the  mean ± SEM of lipid bodies on 50 consecutive eosinophils from three to five independent assays using different donors. *Statistically significant difference between PAF and the vehicle. +Statistically significant differences caused by pretreatment with WEB 2086 or pertussis toxin.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC2199047&req=5

Figure 1: PAF receptor–mediated induction of lipid body formation in eosinophils. (A) Human eosinophils, at a concentration of 106 cells/ml, were treated with PAF (10−8–10−6M) (white squares) or lyso-PAF (10−8– 10−6 M) (black squares) for 1 h at 37°C. (B) Human eosinophils at a concentration of 106 cells/ml were pretreated with WEB 2086 (10–100 μM), pertussis toxin (100 ng/ml), or vehicle for 1 h at 37°C. The cells were then treated with PAF (1 μM) or vehicle for 1 h at 37°C. Lipid bodies were enumerated using light microscopy after osmium staining. Each point represents the mean ± SEM of lipid bodies on 50 consecutive eosinophils from three to five independent assays using different donors. *Statistically significant difference between PAF and the vehicle. +Statistically significant differences caused by pretreatment with WEB 2086 or pertussis toxin.
Mentions: Lipid bodies, although small in number, are normal constituents of leukocytes, including eosinophils. Increased lipid body formation occurs in vivo and can be induced in vitro. In eosinophils obtained from normal donors, within 1 h PAF stimulated a dose-dependent induction of lipid body formation in vitro (Fig. 1 A). In response to 1 μM PAF, lipid body numbers persisted at similar numbers at 1, 4, and 8 h (14.1 ± 0.5, 15.9 ± 0.7, and 9.5 ± 0.5 lipid bodies ± SEM/eosinophil, respectively) with no evidence of enhanced cell death or apoptosis (<7% apoptotic eosinophils at 8 h with and without PAF stimulation). Several findings indicated that the actions of PAF were receptor mediated. First, lyso-PAF failed to induce lipid body formation (Fig. 1 A). Second, the PAF-receptor antagonist WEB 2086 dose-dependently inhibited PAF- induced lipid body formation (Fig. 1 B). Moreover, earlier treatment of cells with pertussis toxin (100 ng/ml, 1 h before PAF) to block PAF-receptor G-protein–mediated signals completely prevented PAF-induced lipid body formation in human eosinophils (Fig. 1 B).

Bottom Line: The specific intracellular sites at which enzymes act to generate arachidonate-derived eicosanoid mediators of inflammation are uncertain.We evaluated the formation and function of cytoplasmic lipid bodies.Thus, lipid bodies are structurally distinct, inducible, nonnuclear sites for enhanced synthesis of paracrine eicosanoid mediators of inflammation.

View Article: PubMed Central - PubMed

Affiliation: Harvard Thorndike Laboratory and Charles A. Dana Research Institute, Beth Israel Deaconess Medical Center, Boston, Massachusetts 02115, USA.

ABSTRACT
The specific intracellular sites at which enzymes act to generate arachidonate-derived eicosanoid mediators of inflammation are uncertain. We evaluated the formation and function of cytoplasmic lipid bodies. Lipid body formation in eosinophils was a rapidly (<1 h) inducible response which was platelet-activating factor (PAF) receptor-mediated, involved signaling through protein kinase C, and required new protein synthesis. In intact and enucleated eosinophils, the PAF-induced increases in lipid body numbers correlated with enhanced production of both lipoxygenase- and cyclooxygenase-derived eicosanoids. All principal eosinophil eicosanoid-forming enzymes, 5-lipoxygenase, leukotriene C4 synthase, and cyclooxygenase, were immunolocalized to native as well as newly induced lipid bodies in intact and enucleated eosinophils. Thus, lipid bodies are structurally distinct, inducible, nonnuclear sites for enhanced synthesis of paracrine eicosanoid mediators of inflammation.

Show MeSH
Related in: MedlinePlus