The immunosuppressant rapamycin represses human immunodeficiency virus type 1 replication

Authors:
Roy J, Paquette JS, Fortin JF and Tremblay MJ
In:
Antimicrob Agents Chemother (2002) 46(11): 3447-3455
Research Area:
Immunotherapy / Hematology
Cells used in publication:
T cell, human peripheral blood unstim.
Species: human
Tissue Origin: blood
Platform:
Nucleofectorâ„¢ I/II/2b
Experiment
The immunosuppressive macrolide rapamycin is used in humans to prevent graft rejection. The authors show that rapamycin significantly down-regulates HIV-1 production in CD4-expressing T cells. HIV-1 replication is linked to the activity of its promoter region positioned in the 5' long terminal repeat (LTR) sequence. A polypyrimidine motif is located within the tat exon 2 of HIV-1. Resting primary human T cells were nucleofected with plasmids containing a 722 bp fragment from HIV-1LAI LTR sequence placed in front of a luciferase reporter (pLTRX-LUC). To reveal the involvement of Tat cells were co-nucleofected with pLTRX-LUC and a Tat vector (pCEP4-Tat). Cell were then either left untreated or treated with PMA/iono (for stimulation of LTR driven expression) or rapamycin. The results suggest that Tat and its associated cellular proteins are less affected by rapamycin than basal HIV-1 LTR activity.
Abstract
The immunosuppressive macrolide rapamycin is used in humans to prevent graft rejection. This drug acts by selectively repressing the translation of proteins that are encoded by an mRNA bearing a 5'-polypyrimidine tract (e.g., ribosomal proteins, elongation factors). The human immunodeficiency virus type 1 (HIV-1) carries a polypyrimidine motif that is located within the tat exon 2. Treatment of human T lymphoid cells with rapamycin resulted in a marked diminution of HIV-1 transcription when infection was performed with luciferase reporter T-tropic and macrophage-tropic viruses. Replication of fully infectious HIV-1 particles was abolished by rapamycin treatment. The rapamycin-mediated inhibitory effect on HIV-1 production was reversed by FK506. The anti-HIV-1 effect of rapamycin was also seen in primary human cells (i.e., peripheral blood lymphocytes) from different healthy donors. Rapamycin was shown to diminish basal HIV-1 long terminal repeat gene expression, and the observed effect of rapamycin on HIV-1 replication seems to be independent of the virus-specific transactivating Tat protein. A constitutive beta-actin promoter-based reporter gene vector was unaffected by rapamycin treatment. Kinetic virus infection studies and exposure to reporter viruses pseudotyped with heterologous envelope proteins (i.e., amphotropic murine leukemia virus and vesicular stomatitis virus G) suggested that rapamycin is primarily affecting the life cycle of HIV-1 at a transcriptional level. Northern blot analysis confirmed that this compound is selectively targeting HIV-1 mRNA synthesis.