Des petits ARN qui voient grand : les microARN et la persistance du VIH-1.

Résumé La thérapie antirétrovirale (TAR) inhibe la réplication du VIH-1 mais n'est pas curative. Pendant la TAR, le génome intégré du VIH-1 persiste principalement dans les lymphocytes T mémoires CD4+ ainsi que dans d'autres cellules immunitaires, notamment les cellules myéloïdes comme les macrophages. La majorité de ces cellules ne produisent pas de particules virales infectieuses et constituent le réservoir latent. D'importants progrès ont été réalisés dans l'identification des facteurs qui contribuent à l'établissement et au maintien du réservoir latent qui demeure le principal obstacle à l'éradication du VIH-1. Dans cette revue, nous mettrons en relief le rôle des microARN dans le développement des réservoirs viraux vu que ceux-ci sont d'importants modulateurs de l'expression génique, ciblant des facteurs de transcription ainsi que d'autres effecteurs nécessaires à l'infection productive du VIH-1. Certains microARN ciblent même directement les transcrits viraux. Nous soulignerons les grandes questions en suspens sur la participation active des microARN de l'hôte aux mécanismes de persistance virale et notamment ceux régissant la latence virale. Finalement, compte tenu des stratégies actuelles qui ne permettent toujours pas de réduire efficacement les réservoirs viraux, les perspectives quant à l'utilisation des microARN comme approche pour contrer la persistance des réservoirs latents seront discutées.

MiRNA-103 downmodulates CCR5 expression reducing human immunodeficiency virus type-1 entry and impacting latency establishment in CD4+ T cells.

Activated-to-memory transitioning CD4+ T cells display elevated expression of the HIV-1 co-receptor CCR5 and are more prone to HIV-1 latent infection. Here, we show that p53-regulated miRNA-103 downmodulates CCR5 levels in CD4+ T lymphocytes. We reveal that miRNA-103 mimics, as well as Nutlin-3, an inhibitor of Mdm2-mediated p53 degradation, decrease CCR5-dependent HIV-1 infection. Using a dual-reporter virus, we subsequently validate that in transitioning CD4+ T cells, Nutlin-3 treatment decreases the frequency of both productively and latently infected cells via upregulation of miRNA-103. Importantly, we provide evidence that CD4+ T cells from HIV-1 elite controllers express less CCR5 than those from antiretroviral therapy-naïve progressors, an effect linked to a significant increase in miRNA-103 levels. By contributing to the control of CCR5 expression in CD4+ T cells, miRNA-103 is likely to play a key role in countering the establishment of latent HIV-1 reservoirs in vivo.

Interleukin-1ß Triggers p53-Mediated Downmodulation of CCR5 and HIV-1 Entry in Macrophages through MicroRNAs 103 and 107.

Macrophages are a target of human immunodeficiency virus type 1 (HIV-1) and may serve as a viral reservoir during antiretroviral therapy (ART). Their susceptibility to HIV-1 infection is subject to variations from permissiveness to resistance depending on their origin, tissue localization, and polarization profile. This is in part due to the expression of regulatory microRNAs. Here, we identify two microRNA paralogs, microRNA 103 (miR-103) and miR-107, as regulators of CCR5 expression that are upregulated in noninfected bystander cells of HIV-1-infected-monocyte-derived macrophage (MDM) cultures. Transfection of microRNA 103 mimics in MDMs reduced CCR5 expression levels and inhibited CCR5-dependent HIV-1 entry, whereas the corresponding antagomirs enhanced virus spread in HIV-infected MDMs. Treatment of MDMs with interleukin-1ß (IL-1ß) enhanced microRNA 103 expression, a condition that we found contributed to the reduction of CCR5 mRNA in IL-1ß-exposed MDMs. Interestingly, we show that the induction of miR-103/107 expression is part of a tumor suppressor p53 response triggered by secreted IL-1ß that renders macrophages refractory to HIV-1 entry. In a more physiological context, the levels of microRNAs 103 and 107 were found enriched in tissue-resident colon macrophages of healthy donors and alveolar macrophages of individuals under antiretroviral therapy, conceivably contributing to their relative resistance to HIV-1 infection. Overall, these findings highlight the role of p53 in enforcing proinflammatory antiviral responses in macrophages, at least in part, through miR-103/107-mediated downmodulation of CCR5 expression and HIV-1 entry.IMPORTANCE Macrophages are heterogeneous immune cells that display varying susceptibilities to HIV-1 infection, in part due to the expression of small noncoding microRNAs involved in the posttranscriptional regulation of gene expression and silencing. Here, we identify microRNAs 103 and 107 as important p53-regulated effectors of the antiviral response triggered by the proinflammatory cytokine IL-1ß in macrophages. These microRNAs, which are enriched in colon macrophages of healthy donors and alveolar macrophages of HIV-infected individuals under antiretroviral therapy, act as inhibitors of HIV-1 entry through their capacity to downregulate the CCR5 coreceptor. These results highlight the important role played by miR-103/107 in modulating CCR5 expression and HIV-1 entry in macrophages. They further underscore a distinct function of the tumor suppressor p53 in enforcing proinflammatory antiviral responses in macrophages, thus providing insight into a cellular pathway that could be targeted to limit the establishment of viral reservoirs in these cells.

Differential utilization of CD4+ by transmitted/founder and chronic envelope glycoproteins in a MSM HIV-1 subtype B transmission cluster.

OBJECTIVE: HIV-1 transmission leads to a genetic bottleneck, with one or a few variants of the donor quasispecies establishing an infection in the new host. We aimed to characterize this bottleneck in more detail, by comparing the properties of HIV envelope glycoproteins from acute and chronic infections within the particular context of a male-to-male transmission cluster. DESIGN: We compared the genotypic and phenotypic properties of envelope glycoproteins from viral variants derived from five study participants from the same transmission cluster. METHODS: We used single-genome amplification to generate a collection of full-length env sequences. We then constructed pseudotyped viruses expressing selected Env variants from the quasispecies infecting each study participant and compared their infectivities and sensitivities to various entry inhibitors. RESULTS: The genotypic analyses confirmed the genetic bottleneck expected after HIV transmission, with a limited number of variants identified in four study participants during acute infection. However, the transmitted sequences harbored no evident common signature and belonged to various genetic lineages. The phenotypic analyses revealed no difference in infectivity, susceptibility to the CCR5 antagonist maraviroc, the fusion inhibitor enfurvitide or type-I interferon between viruses from participants with acute and chronic infections. The key property distinguishing transmitted viruses was a higher resistance to soluble CD4, correlated with greater sensitivity to occupation of the CD4 receptor by the anti-CD4 antibodies LM52 and SK3. CONCLUSION: These results suggest that envelope glycoproteins from transmitted/founder viruses bind CD4 less efficiently than those of viruses from chronic infections.