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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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LC-MS-MS analysis of tryptic peptides from T. gondii protein extract (STAg). (A) Arrows indicate the position of the following protein peptide fragments: A, lactate dehydrogenase; B, enolase; C, dense granule protein 1; D, heat shock protein 70; E, dense granule protein 2; L1, peptide match to Lycopersicon esculentum lipoxygenase A; and L2, peptide match to Persea americana lipoxygenase. (inset) Base peak ion trace for peptide L1. (B) T. gondii proteins identified in STAg.
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fig1: LC-MS-MS analysis of tryptic peptides from T. gondii protein extract (STAg). (A) Arrows indicate the position of the following protein peptide fragments: A, lactate dehydrogenase; B, enolase; C, dense granule protein 1; D, heat shock protein 70; E, dense granule protein 2; L1, peptide match to Lycopersicon esculentum lipoxygenase A; and L2, peptide match to Persea americana lipoxygenase. (inset) Base peak ion trace for peptide L1. (B) T. gondii proteins identified in STAg.

Mentions: STAg injection and live T. gondii infection induce LXA4, 5,15-diHETE, and 15-HETE from endogenous sources at very high levels that appear to be two orders of magnitude greater than those produced during resolution of inflammation (10, 17). To address the possibility that specific T. gondii products evoked LXA4 biosynthesis to suppress host defense, we performed a proteomic analysis of a protein extract of T. gondii (STAg). STAg was digested with trypsin, tryptic peptides were separated by liquid chromatography (Fig. 1 A), and peptide masses and charges were determined by mass spectrometry. Using peptide fingerprinting, 11 known T. gondii proteins were identified (Fig. 1 B). Protein coverage ranged from 4.5 (putative translation initiation factor 5A2) to 44% (lactate dehydrogenase).


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)

LC-MS-MS analysis of tryptic peptides from T. gondii protein extract (STAg). (A) Arrows indicate the position of the following protein peptide fragments: A, lactate dehydrogenase; B, enolase; C, dense granule protein 1; D, heat shock protein 70; E, dense granule protein 2; L1, peptide match to Lycopersicon esculentum lipoxygenase A; and L2, peptide match to Persea americana lipoxygenase. (inset) Base peak ion trace for peptide L1. (B) T. gondii proteins identified in STAg.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2211821&req=5

fig1: LC-MS-MS analysis of tryptic peptides from T. gondii protein extract (STAg). (A) Arrows indicate the position of the following protein peptide fragments: A, lactate dehydrogenase; B, enolase; C, dense granule protein 1; D, heat shock protein 70; E, dense granule protein 2; L1, peptide match to Lycopersicon esculentum lipoxygenase A; and L2, peptide match to Persea americana lipoxygenase. (inset) Base peak ion trace for peptide L1. (B) T. gondii proteins identified in STAg.
Mentions: STAg injection and live T. gondii infection induce LXA4, 5,15-diHETE, and 15-HETE from endogenous sources at very high levels that appear to be two orders of magnitude greater than those produced during resolution of inflammation (10, 17). To address the possibility that specific T. gondii products evoked LXA4 biosynthesis to suppress host defense, we performed a proteomic analysis of a protein extract of T. gondii (STAg). STAg was digested with trypsin, tryptic peptides were separated by liquid chromatography (Fig. 1 A), and peptide masses and charges were determined by mass spectrometry. Using peptide fingerprinting, 11 known T. gondii proteins were identified (Fig. 1 B). Protein coverage ranged from 4.5 (putative translation initiation factor 5A2) to 44% (lactate dehydrogenase).

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