Prostaglandin E2 production by endotoxin-stimulated alveolar macrophages is regulated by phospholipase C pathways. 1996

C J Lo, and H G Cryer, and R V Maier
Department of Surgery, University of California, Los Angeles 90024, USA.

BACKGROUND Eicosanoids play an important role in many aspects of systemic inflammatory responses and host defense. Although the synthesis of eicosanoids by different enzymes has been elucidated, the regulatory mechanism of eicosanoid production is not clear. We designed this study to investigate the hypothesis that PGE2 production by endotoxin (lipopolysaccharide; LPS)-stimulated macrophages (MO) is dependent on phospholipase C (PLC) signaling pathways. METHODS Rabbit alveolar macrophages (MO) were obtained by bronchoalveolar lavage. MO were suspended in RPMI-1640 medium at 1 x 10(6)/mL and were exposed to Escherichia coli LPS (10 ng/mL) +/- various agonists and antagonists of PLC and its secondary messengers. After 24 hours of incubation, prostaglandin E2 (PGE2) production was measured by ELISA. RESULTS LPS-activated MO produced four times as much PGE2 as did control unstimulated MO. The increase in PGE2 production was inhibited by PLC inhibitors (U73122 or D609) and a low-molecular-weight PLA2 inhibitor, manoalide. An increase in intracellular calcium and activation of both the calmodulin and protein kinase C kinase pathways increase PGE2 production. CONCLUSIONS PGE2 production is intimately dependent on several phospholipases. Production is not only dependent on low-molecular-weight PLA2 cleavage of arachidonic acid from membrane phospholipids, but also by-products of PLC activation. PLC-dependent intracellular Ca-calmodulin signaling and protein kinase C activation provide significant modulation of PGE2 production.

UI MeSH Term Description Entries
D008070 Lipopolysaccharides Lipid-containing polysaccharides which are endotoxins and important group-specific antigens. They are often derived from the cell wall of gram-negative bacteria and induce immunoglobulin secretion. The lipopolysaccharide molecule consists of three parts: LIPID A, core polysaccharide, and O-specific chains (O ANTIGENS). When derived from Escherichia coli, lipopolysaccharides serve as polyclonal B-cell mitogens commonly used in laboratory immunology. (From Dorland, 28th ed) Lipopolysaccharide,Lipoglycans
D008297 Male Males
D009102 Multiple Organ Failure A progressive condition usually characterized by combined failure of several organs such as the lungs, liver, kidney, along with some clotting mechanisms, usually postinjury or postoperative. MODS,Multiple Organ Dysfunction Syndrome,Organ Dysfunction Syndrome, Multiple,Organ Failure, Multiple,Failure, Multiple Organ,Multiple Organ Failures
D010738 Type C Phospholipases A subclass of phospholipases that hydrolyze the phosphoester bond found in the third position of GLYCEROPHOSPHOLIPIDS. Although the singular term phospholipase C specifically refers to an enzyme that catalyzes the hydrolysis of PHOSPHATIDYLCHOLINE (EC 3.1.4.3), it is commonly used in the literature to refer to broad variety of enzymes that specifically catalyze the hydrolysis of PHOSPHATIDYLINOSITOLS. Lecithinase C,Phospholipase C,Phospholipases, Type C,Phospholipases C
D011817 Rabbits A burrowing plant-eating mammal with hind limbs that are longer than its fore limbs. It belongs to the family Leporidae of the order Lagomorpha, and in contrast to hares, possesses 22 instead of 24 pairs of chromosomes. Belgian Hare,New Zealand Rabbit,New Zealand Rabbits,New Zealand White Rabbit,Rabbit,Rabbit, Domestic,Chinchilla Rabbits,NZW Rabbits,New Zealand White Rabbits,Oryctolagus cuniculus,Chinchilla Rabbit,Domestic Rabbit,Domestic Rabbits,Hare, Belgian,NZW Rabbit,Rabbit, Chinchilla,Rabbit, NZW,Rabbit, New Zealand,Rabbits, Chinchilla,Rabbits, Domestic,Rabbits, NZW,Rabbits, New Zealand,Zealand Rabbit, New,Zealand Rabbits, New,cuniculus, Oryctolagus
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D015232 Dinoprostone The most common and most biologically active of the mammalian prostaglandins. It exhibits most biological activities characteristic of prostaglandins and has been used extensively as an oxytocic agent. The compound also displays a protective effect on the intestinal mucosa. PGE2,PGE2alpha,Prostaglandin E2,Prostaglandin E2alpha,PGE2 alpha,Prepidil Gel,Prostaglandin E2 alpha,Prostenon,E2 alpha, Prostaglandin,E2, Prostaglandin,E2alpha, Prostaglandin,Gel, Prepidil,alpha, PGE2,alpha, Prostaglandin E2
D015398 Signal Transduction The intracellular transfer of information (biological activation/inhibition) through a signal pathway. In each signal transduction system, an activation/inhibition signal from a biologically active molecule (hormone, neurotransmitter) is mediated via the coupling of a receptor/enzyme to a second messenger system or to an ion channel. Signal transduction plays an important role in activating cellular functions, cell differentiation, and cell proliferation. Examples of signal transduction systems are the GAMMA-AMINOBUTYRIC ACID-postsynaptic receptor-calcium ion channel system, the receptor-mediated T-cell activation pathway, and the receptor-mediated activation of phospholipases. Those coupled to membrane depolarization or intracellular release of calcium include the receptor-mediated activation of cytotoxic functions in granulocytes and the synaptic potentiation of protein kinase activation. Some signal transduction pathways may be part of larger signal transduction pathways; for example, protein kinase activation is part of the platelet activation signal pathway. Cell Signaling,Receptor-Mediated Signal Transduction,Signal Pathways,Receptor Mediated Signal Transduction,Signal Transduction Pathways,Signal Transduction Systems,Pathway, Signal,Pathway, Signal Transduction,Pathways, Signal,Pathways, Signal Transduction,Receptor-Mediated Signal Transductions,Signal Pathway,Signal Transduction Pathway,Signal Transduction System,Signal Transduction, Receptor-Mediated,Signal Transductions,Signal Transductions, Receptor-Mediated,System, Signal Transduction,Systems, Signal Transduction,Transduction, Signal,Transductions, Signal
D016676 Macrophages, Alveolar Round, granular, mononuclear phagocytes found in the alveoli of the lungs. They ingest small inhaled particles resulting in degradation and presentation of the antigen to immunocompetent cells. Alveolar Macrophages,Macrophages, Pulmonary,Pulmonary Macrophages,Macrophage, Pulmonary,Pulmonary Macrophage,Alveolar Macrophage,Macrophage, Alveolar

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