Glutamate metabolism in HIV-infected macrophages: implications for the CNS

• Published in: American Journal of Physiology: Cell Physiology Vol. 291; no. 4; pp. C618 - C626
• Main Authors: Porcheray, Fabrice, Leone, Cathie, Samah, Boubekeur, Rimaniol, Anne-Cecile, Dereuddre-Bosquet, Nathalie, Gras, Gabriel
• Format: Journal Article
• Language: English
• Published: United States American Physiological Society 01.10.2006
• Subjects: Anti-Inflammatory Agents - pharmacology; Cells, Cultured; Cellular biology; Excitatory Amino Acid Transporter 1 - genetics; Excitatory Amino Acid Transporter 1 - metabolism; Gene expression; Gene Expression Regulation, Viral; Glutamate Plasma Membrane Transport Proteins - metabolism; Glutamate-Ammonia Ligase - genetics; Glutamate-Ammonia Ligase - metabolism; Glutamic Acid - metabolism; Glutamic Acid - pharmacokinetics; HIV; HIV - physiology; HIV Infections - metabolism; HIV Infections - virology; Human immunodeficiency virus; Humans; Inflammation Mediators - pharmacology; Lipopolysaccharides - pharmacology; Macrophages - metabolism; Metabolism; Protein synthesis; Studies; Transcription, Genetic; Up-Regulation; Virus Replication - physiology
• ISSN: 0363-6143; 1522-1563
• DOI: 10.1152/ajpcell.00021.2006

1 Commissariat à l'Energie Atomique, CEA, DSV/DRM/SNV, Unité Mixte de Recherche E-01 Université Paris-Sud XI, Centre de Recherches du Service de Santé des Armées, IFR13 Institut Paris Sud Cytokines, Laboratoire de Neuro-Immuno-Virologie, Fontenay-aux-Roses; and 2 Société de Pharmacologie et d'Immunologie-BIO, Commissariat à l'Energie Atomique, Fontenay-aux-Roses, France Submitted 19 January 2006 ; accepted in final form 5 May 2006 Central nervous system disorders are still a common complication of human immunodeficiency virus (HIV) infection and can lead to dementia and death. They are mostly the consequences of an inflammatory macrophagic activation and relate to glutamate-mediated excitotoxicity. However, recent studies also suggest neuroprotective aspects of macrophage activation through the expression of glutamate transporters and glutamine synthetase. We thus aimed to study whether HIV infection or activation of macrophages could modulate glutamate metabolism in these cells. We assessed the effect of HIV infection on glutamate transporter expression as well as on glutamate uptake by macrophages and showed that glutamate transport was partially decreased in the course of virus replication, whereas excitatory amino acid transporter-2 (EAAT-2) gene expression was dramatically increased. The consequences of HIV infection on glutamine synthetase were also measured and for the first time we show the functional expression of this key enzyme in macrophages. This expression was repressed during virus production. We then quantified EAAT-1 and EAAT-2 gene expression as well as glutamate uptake in differentially activated macrophages and show that the effects of HIV are not directly related to pro- or anti-inflammatory mediators. Finally, this study shows that glutamate transport by macrophages is less affected than what has been described in astrocytes. Macrophages may thus play a role in neuroprotection against glutamate in the infected brain, through their expression of both EAATs and glutamine synthetase. Because glutamate metabolism by activated macrophages is sensitive to both HIV infection and inflammation, it may thus be of potential interest as a therapeutic target in HIV encephalitis. excitatory amino acid transporter; cystine-glutamate antiporter; glutathione; inflammation; oxidative stress; glutamine synthetase Address for reprint requests and other correspondence: G. Gras, Laboratoire de Neuro-Immuno-Virologie, Commissariat à l'Energie Atomique, DSV/DRM/SNV, 18 route du Panorama, F92265 Fontenay-aux-Roses cedex, France (e-mail: gabriel.gras{at}cea.fr )