HIV Tat acts on endogenous retroviruses of the W family and this occurs via Toll-like receptor 4: inference for neuroAIDS
The objective of this study is to verify whether HIV activates two endogenous retroviruses of the human endogenous retrovirus (HERV)-W family, multiple sclerosis-associated retrovirus (MSRV) and Syncytin-1, whose neuropathogenic and immunopathogenic properties could contribute to HIV-related neurode...
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Veröffentlicht in: | AIDS (London) 2014-11, Vol.28 (18), p.2659-2670 |
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Zusammenfassung: | The objective of this study is to verify whether HIV activates two endogenous retroviruses of the human endogenous retrovirus (HERV)-W family, multiple sclerosis-associated retrovirus (MSRV) and Syncytin-1, whose neuropathogenic and immunopathogenic properties could contribute to HIV-related neurodegeneration.
Peripheral blood mononuclear cells, monocyte-macrophages and astrocytes were either infected by HIV or exposed to HIV-Tat, and/or other treatments. The expression of transcripts and proteins of interest was evaluated by real-time RT-PCR and western blotting assays, respectively.
HIV and Tat increase the levels of MSRVenv mRNAs and HERV-Wenv proteins in astrocytes and in blood cells. In monocyte-macrophages, Tat also induces high levels of CCR2, CD16 and Toll-like receptor 4 (TLR4) molecules. Syncytin-1 response to Tat depends on the cell context: in monocytes, Tat stimulates MSRVenv and inhibits Syncytin-1, while in differentiated macrophages, it stimulates both elements. In primary astrocytes, Tat stimulates MSRV and Syncytin-1 indirectly, through interaction with TLR4 and induction of tumour necrosis factor-alpha (TNFα), without internalization.
In-vivo consequence of the study could be that, through increase of CD16 and CCR2, Tat promotes neuroinvasion not only by HIV-infected monocytes/macrophages but also by the HERV-Ws, with their neuropathogenic potential. Also, the novel finding of TLR4 stimulation by Tat may be of relevance, as TLR4 is critical in neuroinflammation. Within central nervous system (CNS), Tat-induced TNFα could induce high levels of the HERV-Ws, in both macrophages and astrocytes, also without HIV replication. The indirect mechanism by which Tat activates the HERV-Ws through induction of TNFα could add a new piece to the puzzle of CNS pathogenesis, that is the HERV-Wenv contribute to the HIV-related neurodegeneration. |
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ISSN: | 0269-9370 1473-5571 |
DOI: | 10.1097/QAD.0000000000000477 |