Abstract
Human immunodeficiency virus type-1 (HIV-1) infection of monocyte/macrophages is modulated by the levels of entry receptors cluster of differentiation 4 (CD4) and C-C chemokine receptor type 5 (CCR5), as well as by host antiviral restriction factors, which mediate several post-entry blocks. We recently identified two microRNAs, miR-221 and miR-222, which limit HIV-1 entry during infection of monocyte-derived macrophages (MDMs) by down-regulating CD4 expression. Interestingly, CD4 is also down-regulated during the differentiation of monocytes into macrophages. In this study, we compared microRNA expression profiles in primary monocytes and macrophages by RNAseq and found that miR-221/miR-222 are enhanced in macrophages. We took advantage of the monocytic THP-1 cell line that, once differentiated, is poorly susceptible to HIV-1. Accordingly, we found that CD4 levels are very low in THP-1 differentiated cells and that this down-regulation of the virus receptor is the result of miR-221/miR-222 up-regulation during differentiation. We thus established a THP-1 cell line stably expressing a modified CD4 (THP-1-CD4R) that is not modulated by miR-221/miR-222. We show that in contrast to parental THP-1, this line is productively infected by HIV-1 following differentiation, sustaining efficient HIV-1 CD4-dependent replication and spread. This new THP-1-CD4R cell line represents a useful tool for the study of HIV-1-macrophage interactions particularly in contexts where spreading of viral infection is necessary.
Highlights
Macrophages make up a heterogeneous population of cells and are important components of innate immunity
We show that miR-221 and miR-222 are among the up-regulated microRNAs following monocyte differentiation into macrophages, both in primary cells and in the monocytic THP-1 model cell line
In order to confirm the modulation of cluster of differentiation 4 (CD4), we first compared the levels of both CD4 mRNA and surface expression in monocytes and derived macrophages of either human primary myeloid cells or the established THP-1 human monocytic cell line that can be differentiated into adherent macrophage-like cells following phorbol 12-myristate 13-acetate (PMA) treatment [41]
Summary
Macrophages make up a heterogeneous population of cells and are important components of innate immunity. (HIV-1) infection, infected macrophages are more resistant to virus-mediated cytopathic effects and are not significantly depleted in vivo [1,2]. As such, they are thought to promote viral spread and the establishment of persistent viral reservoirs [3]. The stage of differentiation as well as the activation status of macrophages profoundly affect their susceptibility to HIV-1 infection [3]. While cells of the monocyte lineage in peripheral blood are rarely infected in vivo [1,4], differentiation of monocytes into macrophages in some tissues, such as the brain or lung, can result in susceptibility to infection [5].
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