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Exogenous pathogen and plant 15-lipoxygenase initiate endogenous lipoxin A4 biosynthesis.

Bannenberg GL, Aliberti J, Hong S, Sher A, Serhan C - J. Exp. Med. (2004)

Bottom Line: Hence, we incubated STAg itself with arachidonic acid and found using LC-UV-MS-MS-based lipidomics that STAg produced both 15-HETE and 5,15-diHETE, indicating that T. gondii carries 15-lipoxygenase activity.Local administration of a plant (soybean) lipoxygenase itself reduced neutrophilic infiltration in murine peritonitis, demonstrating that 15-lipoxygenase possesses antiinflammatory properties.Together, these results indicate that 15-lipoxygenase expressed by a pathogen as well as exogenously administered 15-lipoxygenase can interact with host biosynthetic circuits for endogenous "stop signals" that divert the host immune response and limit acute inflammation.

View Article: PubMed Central - PubMed

Affiliation: Center for Experimental Therapeutics and Reperfusion Injury, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.

ABSTRACT
Lipoxin A4 (LXA4) is a potent endogenous lipoxygenase-derived eicosanoid with antiinflammatory and proresolving properties. Supraphysiological levels of LXA4 are generated during infection by Toxoplasma gondii, which in turn reduces interleukin (IL) 12 production by dendritic cells, thus dampening Th1-type cell-mediated immune responses and host immunopathology. In the present work, we sought evidence for the structural basis of T. gondii's ability to activate LXA4 biosynthesis. Proteomic analysis of T. gondii extract (soluble tachyzoite antigen [STAg]), which preserves the immunosuppressive and antiinflammatory activity of the parasite, yielded several peptide matches to known plant lipoxygenases. Hence, we incubated STAg itself with arachidonic acid and found using LC-UV-MS-MS-based lipidomics that STAg produced both 15-HETE and 5,15-diHETE, indicating that T. gondii carries 15-lipoxygenase activity. In addition, T. gondii tachyzoites (the rapidly multiplying and invasive stage of the parasite) generated LXA4 when provided with arachidonic acid. Local administration of a plant (soybean) lipoxygenase itself reduced neutrophilic infiltration in murine peritonitis, demonstrating that 15-lipoxygenase possesses antiinflammatory properties. Administration of plant 15-lipoxygenase generated endogenous LXA4 and mimicked the suppression of IL-12 production by splenic dendritic cells observed after T. gondii infection or STAg administration. Together, these results indicate that 15-lipoxygenase expressed by a pathogen as well as exogenously administered 15-lipoxygenase can interact with host biosynthetic circuits for endogenous "stop signals" that divert the host immune response and limit acute inflammation.

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Plant 15-lipoxygenase reduces dendritic cell IL-12 production in vivo. (A) Intraperitoneal administration of plant 15-lipoxygenase mimics STAg-induced paralysis of splenic dendritic cells. Mice were injected i.p. with 1 μg STAg, 103 U soybean lipoxygenase, or vehicle alone 18 h before a second challenge with 1 μg STAg, 103 U soybean lipoxygenase, or vehicle. 6 h later, splenic dendritic cells were harvested and cultured for another 12 h. Dendritic cell formation of IL-12 p40 was measured (see Materials and Methods) and expressed as mean values ± SEM (n = 3). (B) Dose-dependent induction of dendritic cell paralysis (see Introduction and references 8–10 and 16 for details) by i.p. administration of plant 15-lipoxygenase requires catalytic activity. Mice were injected intraperitoneally with native (closed circles), boiled (open circles) soybean lipoxygenase, or vehicle alone 18 h before a second challenge with 1 μg STAg (i.p.) or vehicle. 6 h later, splenic dendritic cells were harvested and cultured for another 12 h. IL-12 p40 was measured (see Materials and Methods) and expressed as mean values ± SEM (n = 3).
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fig5: Plant 15-lipoxygenase reduces dendritic cell IL-12 production in vivo. (A) Intraperitoneal administration of plant 15-lipoxygenase mimics STAg-induced paralysis of splenic dendritic cells. Mice were injected i.p. with 1 μg STAg, 103 U soybean lipoxygenase, or vehicle alone 18 h before a second challenge with 1 μg STAg, 103 U soybean lipoxygenase, or vehicle. 6 h later, splenic dendritic cells were harvested and cultured for another 12 h. Dendritic cell formation of IL-12 p40 was measured (see Materials and Methods) and expressed as mean values ± SEM (n = 3). (B) Dose-dependent induction of dendritic cell paralysis (see Introduction and references 8–10 and 16 for details) by i.p. administration of plant 15-lipoxygenase requires catalytic activity. Mice were injected intraperitoneally with native (closed circles), boiled (open circles) soybean lipoxygenase, or vehicle alone 18 h before a second challenge with 1 μg STAg (i.p.) or vehicle. 6 h later, splenic dendritic cells were harvested and cultured for another 12 h. IL-12 p40 was measured (see Materials and Methods) and expressed as mean values ± SEM (n = 3).

Mentions: To determine whether the 15-lipoxygenase activity could account for the in vivo paralysis of splenic dendritic cells that is known to occur after T. gondii or STAg administration (compare with reference 10), we determined IL-12 generation by splenic dendritic cells from STAg- and/or 15-lipoxygenase–treated mice. Administration of 1,000 U of soybean 15-lipoxygenase (i.p.) markedly reduced splenic dendritic cell IL-12 generation induced by a second challenge with STAg, namely the dendritic cell paralysis procedure (Fig. 5 A; reference 10). Intraperitoneal administration of the plant arachidonate 15-lipoxygenase induced a dose-dependent reduction in splenic dendritic cell IL-12 production with a nadir at 10.000 U (Fig. 5 B). The shape of the dose–response curve indicates that a complex relationship exists between activity and the temporal and spatial distribution of the immunosuppressive action of exogenously administered 15-lipoxygenase. Heat inactivation of the soybean 15-lipoxygenase (100°C for 60 s) before in vivo administration abolished its impact on IL-12 formation, strongly suggesting that the catalytic activity of 15-lipoxygenase is required for the inhibition in vivo of dendritic cell IL-12 generation. We also observed that local administration of high doses of the lipoxygenase (5 × 105 and 106 U) led to local bleeding and death of mice. This indicates that adverse actions by lipoxygenase, namely overdosing, can occur, that may also be responsible for the observed lack of inhibitory action on dendritic cell IL-12 formation observed after local administration of 105 U, giving rise to the V-shaped dose–response (Fig. 5 B). Together, these results indicate that at the lower doses used, 15-lipoxygenase administered in vivo mimics the suppression of dendritic cell IL-12 generation that is evoked with T. gondii infection and STAg administration.


Exogenous pathogen and plant 15-lipoxygenase initiate endogenous lipoxin A4 biosynthesis.

Bannenberg GL, Aliberti J, Hong S, Sher A, Serhan C - J. Exp. Med. (2004)

Plant 15-lipoxygenase reduces dendritic cell IL-12 production in vivo. (A) Intraperitoneal administration of plant 15-lipoxygenase mimics STAg-induced paralysis of splenic dendritic cells. Mice were injected i.p. with 1 μg STAg, 103 U soybean lipoxygenase, or vehicle alone 18 h before a second challenge with 1 μg STAg, 103 U soybean lipoxygenase, or vehicle. 6 h later, splenic dendritic cells were harvested and cultured for another 12 h. Dendritic cell formation of IL-12 p40 was measured (see Materials and Methods) and expressed as mean values ± SEM (n = 3). (B) Dose-dependent induction of dendritic cell paralysis (see Introduction and references 8–10 and 16 for details) by i.p. administration of plant 15-lipoxygenase requires catalytic activity. Mice were injected intraperitoneally with native (closed circles), boiled (open circles) soybean lipoxygenase, or vehicle alone 18 h before a second challenge with 1 μg STAg (i.p.) or vehicle. 6 h later, splenic dendritic cells were harvested and cultured for another 12 h. IL-12 p40 was measured (see Materials and Methods) and expressed as mean values ± SEM (n = 3).
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Related In: Results  -  Collection

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fig5: Plant 15-lipoxygenase reduces dendritic cell IL-12 production in vivo. (A) Intraperitoneal administration of plant 15-lipoxygenase mimics STAg-induced paralysis of splenic dendritic cells. Mice were injected i.p. with 1 μg STAg, 103 U soybean lipoxygenase, or vehicle alone 18 h before a second challenge with 1 μg STAg, 103 U soybean lipoxygenase, or vehicle. 6 h later, splenic dendritic cells were harvested and cultured for another 12 h. Dendritic cell formation of IL-12 p40 was measured (see Materials and Methods) and expressed as mean values ± SEM (n = 3). (B) Dose-dependent induction of dendritic cell paralysis (see Introduction and references 8–10 and 16 for details) by i.p. administration of plant 15-lipoxygenase requires catalytic activity. Mice were injected intraperitoneally with native (closed circles), boiled (open circles) soybean lipoxygenase, or vehicle alone 18 h before a second challenge with 1 μg STAg (i.p.) or vehicle. 6 h later, splenic dendritic cells were harvested and cultured for another 12 h. IL-12 p40 was measured (see Materials and Methods) and expressed as mean values ± SEM (n = 3).
Mentions: To determine whether the 15-lipoxygenase activity could account for the in vivo paralysis of splenic dendritic cells that is known to occur after T. gondii or STAg administration (compare with reference 10), we determined IL-12 generation by splenic dendritic cells from STAg- and/or 15-lipoxygenase–treated mice. Administration of 1,000 U of soybean 15-lipoxygenase (i.p.) markedly reduced splenic dendritic cell IL-12 generation induced by a second challenge with STAg, namely the dendritic cell paralysis procedure (Fig. 5 A; reference 10). Intraperitoneal administration of the plant arachidonate 15-lipoxygenase induced a dose-dependent reduction in splenic dendritic cell IL-12 production with a nadir at 10.000 U (Fig. 5 B). The shape of the dose–response curve indicates that a complex relationship exists between activity and the temporal and spatial distribution of the immunosuppressive action of exogenously administered 15-lipoxygenase. Heat inactivation of the soybean 15-lipoxygenase (100°C for 60 s) before in vivo administration abolished its impact on IL-12 formation, strongly suggesting that the catalytic activity of 15-lipoxygenase is required for the inhibition in vivo of dendritic cell IL-12 generation. We also observed that local administration of high doses of the lipoxygenase (5 × 105 and 106 U) led to local bleeding and death of mice. This indicates that adverse actions by lipoxygenase, namely overdosing, can occur, that may also be responsible for the observed lack of inhibitory action on dendritic cell IL-12 formation observed after local administration of 105 U, giving rise to the V-shaped dose–response (Fig. 5 B). Together, these results indicate that at the lower doses used, 15-lipoxygenase administered in vivo mimics the suppression of dendritic cell IL-12 generation that is evoked with T. gondii infection and STAg administration.

Bottom Line: Hence, we incubated STAg itself with arachidonic acid and found using LC-UV-MS-MS-based lipidomics that STAg produced both 15-HETE and 5,15-diHETE, indicating that T. gondii carries 15-lipoxygenase activity.Local administration of a plant (soybean) lipoxygenase itself reduced neutrophilic infiltration in murine peritonitis, demonstrating that 15-lipoxygenase possesses antiinflammatory properties.Together, these results indicate that 15-lipoxygenase expressed by a pathogen as well as exogenously administered 15-lipoxygenase can interact with host biosynthetic circuits for endogenous "stop signals" that divert the host immune response and limit acute inflammation.

View Article: PubMed Central - PubMed

Affiliation: Center for Experimental Therapeutics and Reperfusion Injury, Department of Anesthesiology, Perioperative and Pain Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.

ABSTRACT
Lipoxin A4 (LXA4) is a potent endogenous lipoxygenase-derived eicosanoid with antiinflammatory and proresolving properties. Supraphysiological levels of LXA4 are generated during infection by Toxoplasma gondii, which in turn reduces interleukin (IL) 12 production by dendritic cells, thus dampening Th1-type cell-mediated immune responses and host immunopathology. In the present work, we sought evidence for the structural basis of T. gondii's ability to activate LXA4 biosynthesis. Proteomic analysis of T. gondii extract (soluble tachyzoite antigen [STAg]), which preserves the immunosuppressive and antiinflammatory activity of the parasite, yielded several peptide matches to known plant lipoxygenases. Hence, we incubated STAg itself with arachidonic acid and found using LC-UV-MS-MS-based lipidomics that STAg produced both 15-HETE and 5,15-diHETE, indicating that T. gondii carries 15-lipoxygenase activity. In addition, T. gondii tachyzoites (the rapidly multiplying and invasive stage of the parasite) generated LXA4 when provided with arachidonic acid. Local administration of a plant (soybean) lipoxygenase itself reduced neutrophilic infiltration in murine peritonitis, demonstrating that 15-lipoxygenase possesses antiinflammatory properties. Administration of plant 15-lipoxygenase generated endogenous LXA4 and mimicked the suppression of IL-12 production by splenic dendritic cells observed after T. gondii infection or STAg administration. Together, these results indicate that 15-lipoxygenase expressed by a pathogen as well as exogenously administered 15-lipoxygenase can interact with host biosynthetic circuits for endogenous "stop signals" that divert the host immune response and limit acute inflammation.

Show MeSH
Related in: MedlinePlus