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Journal of Virology, July 2000, p. 6433-6441, Vol. 74, No. 14
Experimental Neurobiology and Physiopathology
Unit, INSERM U433,1 and Hôpital
Neurologique,2 Lyon, France
Received 3 December 1999/Accepted 26 April 2000
Human T-cell lymphotropic virus type 1 (HTLV-1) is the causative
agent of a chronic progressive myelopathy called tropical spastic
paraparesis/HTLV-1-associated myelopathy (TSP/HAM). In this disease,
lesions of the central nervous system (CNS) are associated with
perivascular infiltration by lymphocytes. We and others have
hypothesized that these T lymphocytes infiltrating the CNS may play a
prominent role in TSP/HAM. Here, we show that transient contact of
human or rat astrocytes with T lymphocytes chronically infected by
HTLV-1 impairs some of the major functions of brain astrocytes. Uptake
of extracellular glutamate by astrocytes was significantly decreased
after transient contact with infected T cells, while the expression of
the glial transporters GLAST and GLT-1 was decreased. In
two-compartment cultures avoiding direct cell-to-cell contact, similar
results were obtained, suggesting possible involvement of soluble
factors, such as cytokines and the viral protein Tax-1. Recombinant
Tax-1 and tumor necrosis factor alpha (TNF-
0022-538X/00/$04.00+0
Copyright © 2000, American Society for Microbiology. All rights reserved.
Human T-Cell Lymphotropic Virus Type 1-Infected T
Lymphocytes Impair Catabolism and Uptake of Glutamate by Astrocytes via
Tax-1 and Tumor Necrosis Factor Alpha
) decreased glutamate
uptake by astrocytes. Tax-1 probably acts by inducing TNF-
, as the
effect of Tax-1 was abolished by anti-TNF-
antibody. The expression
of glutamate-catabolizing enzymes in astrocytes was increased for
glutamine synthetase and decreased for glutamate dehydrogenase, the
magnitudes of these effects being correlated with the level of Tax-1
transcripts. In conclusion, Tax-1 and cytokines produced by
HTLV-1-infected T cells impair the ability of astrocytes to manage the
steady-state level of glutamate, which in turn may affect neuronal and
oligodendrocytic functions and survival.
*
Corresponding author. Mailing address: INSERM U433,
Faculté de Médecine Laënnec, F69372 Lyon cedex 08, France. Phone: (33) 4 7877 8759. Fax: (33) 4 7877 8616. E-mail:
giraudon{at}lyon151.inserm.fr.
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