Bacterial Lipopolysaccharides Modify Signal Transduction in the Arachidonic Acid Cascade in Macrophages

Aderem, Alan; Cohn, Zanvil A.

doi:10.1002/9780470720998.ch13

Cited by 8 publications

(3 citation statements)

References 30 publications

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“…Nonreceptor-mediated ionophores such as ionomycin, and purinergic receptor activation by high levels of adenosine triphosphate (ATP), can produce sustained changes in intracellular Ca 2ϩ levels that induce eicosanoid production (21,23,24). Furthermore, the response to Ca 2ϩ agonists has been shown to be synergistically increased by priming cells with a 60-min dose of a TLR activator (21,(25)(26)(27)(28)(29), producing more eicosanoid release than the additive amount of TLR and Ca 2ϩ stimulation alone. Here we employed LC/MS/MS methodology to specifically investigate these mechanisms of eicosanoid generation, identifying two distinct eicosanoid profiles.…”

Section: Bis(palmitoyloxy)-(2r2s)-propyl]-cys-[s]-mentioning

confidence: 99%

TLR-4 and Sustained Calcium Agonists Synergistically Produce Eicosanoids Independent of Protein Synthesis in RAW264.7 Cells

Buczynski

Stephens

Bowers-Gentry

et al. 2007

Journal of Biological Chemistry

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Arachidonic acid is released by phospholipase A 2 and converted into hundreds of distinct bioactive mediators by a variety of cyclooxygenases (COX), lipoxygenases (LO), and cytochrome P450s. Because of the size and diversity of the eicosanoid class of signaling molecules produced, a thorough and systematic investigation of these biological processes requires the simultaneous quantitation of a large number of eicosanoids in a single analysis. We have developed a robust liquid chromatography/tandem mass spectrometry method that can identify and quantitate over 60 different eicosanoids in a single analysis, and we applied it to agoniststimulated RAW264.7 murine macrophages. Fifteen different eicosanoids produced through COX and 5-LO were detected either intracellularly or in the media following stimulation with 16 different agonists of Toll-like receptors (TLR), G protein-coupled receptors, and purinergic receptors. No significant differences in the COX metabolite profiles were detected using the different agonists; however, we determined that only agonists creating a sustained Ca 2؉ influx were capable of activating the 5-LO pathway in these cells. Synergy between Ca 2؉ and TLR pathways was detected and discovered to be independent of NF-B-induced protein synthesis. This demonstrates that TLR induction of protein synthesis and priming for enhanced phospholipase A 2 -mediated eicosanoid production work through two distinct pathways.

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Section: Bis(palmitoyloxy)-(2r2s)-propyl]-cys-[s]-mentioning

confidence: 99%

TLR-4 and Sustained Calcium Agonists Synergistically Produce Eicosanoids Independent of Protein Synthesis in RAW264.7 Cells

Buczynski

Stephens

Bowers-Gentry

et al. 2007

Journal of Biological Chemistry

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“…Via PLA 2 activation, LPS induce accumulation of unsaturated lipids in monocytes, resulting in an increase in monocyte membrane fluidity (19). Thus, LPS can activate the arachidonic acid cascade (20,21). Thrombin generation by TF in recalcified pooled normal plasma.…”

Section: Discussionmentioning

confidence: 99%

Thrombin Generation by Exposure of Blood to Endotoxin: A Simple Model to Study Disseminated Intravascular Coagulation

Stief

2006

Clin Appl Thromb Hemost

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Pathologic disseminated intravascular coagulation (PDIC) is a serious complication in sepsis. In an in-vitro system consisting of incubation of fresh citrated blood with lipopolysaccharides (LPS) or glucans and subsequent plasma recalcification plasmatic thrombin was quantified. Five hundred microliters of freshly drawn citrated blood of healthy donors were incubated with up to 800 ng/mL LPS ( Escherichia coli) or up to 80 μg/mL Zymosan A (ZyA; Candida albicans) for 30 minutes at room temperature (RT). The samples were centrifuged, and 30 μL plasma were recalcified with 1 volume or less of CaCl2 (25 μmoles Ca2+/mL plasma). After 0 to 12 minutes (37°C), 20 μL 2.5 M arginine, pH 8.6, were added. Thirty microliters 0.9 m M HD-CHG-Ala-Arg-pNA in 2.3 M arginine were added, and the absorbance increase at 405 nm was determined. Fifty microliters plasma were also incubated with 5 μL 250 m M CaCl2 for 5, 10, or 15 minutes (37°C). Fifty microliters 2.5 M arginine stops coagulation, and 50 μL 0.77 m M HD-CHG-Ala-Arg-pNA in 2.3 M arginine starts the thrombin detection. The standard was 1 IU/mL thrombin in 7% human albumin instead of plasma. Arginine was also added in the endotoxin exposure time (EET) or in the plasma coagulation reaction time (CRT). Tissue factor (TF)-antigen and soluble CD14 were determined. LPS at blood concentrations greater than 10 ng/mL or ZyA at greater than 1 μg/mL severalfold enhance thrombin generation, when the respective plasmas are recalcified. After 30 minutes EET at RT, the thrombin activity at 12 minutes CRT generated by the addition of 200 ng/mL LPS or 20 μg/mL ZyA is approximately 200 mIU/mL compared to approximately 20 mIU/mL without addition of endotoxin, or compared to about 7 mIU/mL thrombin at 0 minutes CRT. Arginine added to blood or to plasma inhibits thrombin generation; the inhibitory concentration 50% (IC 50) is approximately 15 m M plasma concentration. Endotoxin incubation of blood increases neither TF nor sCD14. This assay allows the study of the hemostasis alteration in PDIC, particularly in PDIC by sepsis. The thrombin generated by blood plus endotoxin incubation and plasma recalcification suggests that the contact phase of coagulation; e.g., triggered by cell components of (phospholipase-) lysed cells such as monocyte or endothelium DNA or phospholipid-vesicles (microparticles), is of primary pathologic importance in sepsis-PDIC. Arginine at plasma concentrations of 10 to 50 m M might be a new therapeutic for sepsis-PDIC.

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“…63 Thus, LPS can activate the arachidonic acid cascade. 64,65 Furthermore, LPS induce expression of PLA 2 in macrophages 66 and seem to activate oxygen radical production in monocytes. 67 Phospholipase A 2 releases arachidonic acid that stimulates reduced nicotinamide adenine dinucleotide phosphate oxidase and induces membrane redistribution; PLC releasesinositol-3,4,5-triphosphate and diacylglycerol that stimulate NADPH oxidase and protein kinase C. 68 Phospholipase A 2 is also activated by diacylglycerol.…”

Section: Susceptibility Of Cells Of the Blood Streammentioning

confidence: 99%

Coagulation Activation by Lipopolysaccharides

Stief

2007

Clin Appl Thromb Hemost

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Lipopolysaccharides at approximate plasma reactivities >3 ng/mL or beta-glucans at >0.5-1 Amicrog/mL are toxic for human blood; lipopolysaccharide interacts with membrane components of susceptible cells (eg, monocytes) activating phospholipase A(2) that destroys the cell membrane. Cell fragments (microparticles or DNA) possess polynegative niches that activate intrinsic hemostasis. Pathologic disseminated intravascular coagulation arises. Blood vessels are obstructed by disseminated thrombi, and vital organ areas become ischemic. Multiorgan failure threatens life of the patient. Diagnosis and therapy of pathologic disseminated intravascular coagulation is of extreme clinical importance. For early diagnosis of pathologic disseminated intravascular coagulation, specific activation markers of coagulation (eg, plasmatic amidolytic thrombin activity) or the plasmatic lipopolysaccharide or glucan reactivity can be measured. A new treatment target might be kallikrein or factor XIIa; 10 to 20 mM arginine is the approximate 50% inhibitory concentration against the contact phase of coagulation. The complex interaction between cell fragments and hemostasis causes pathologic disseminated intravascular coagulation in sepsis.

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Bacterial Lipopolysaccharides Modify Signal Transduction in the Arachidonic Acid Cascade in Macrophages

Cited by 8 publications

References 30 publications

TLR-4 and Sustained Calcium Agonists Synergistically Produce Eicosanoids Independent of Protein Synthesis in RAW264.7 Cells

TLR-4 and Sustained Calcium Agonists Synergistically Produce Eicosanoids Independent of Protein Synthesis in RAW264.7 Cells

Thrombin Generation by Exposure of Blood to Endotoxin: A Simple Model to Study Disseminated Intravascular Coagulation

Coagulation Activation by Lipopolysaccharides

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