Latent HIV-1 Infection Occurs in Multiple Subsets of Hematopoietic Progenitor Cells and Is Reversed by NF-κB Activation

Abstract

The ability of HIV-1 to establish a latent infection presents a barrier to curing HIV. The best-studied reservoir of latent virus in vivo is resting memory CD4 + T cells, but it has recently been shown that CD34 + hematopoietic progenitor cells (HPCs) can also become latently infected by HIV-1 in vitro and in vivo . CD34 + cells are not homogenous, however, and it is not yet known which types of CD34 + cells support a latent infection. Furthermore, the mechanisms through which latency is established in this cell type are not yet known. Here we report the development of a primary cell model for latent HIV-1 infection in HPCs. We demonstrate that in this model, latent infection can be established in all subsets of HPCs examined, including HPCs with cell surface markers consistent with immature hematopoietic stem and progenitor cells. We further show that the establishment of latent infection in these cells can be reversed by tumor necrosis factor alpha (TNF-α) through an NF-κB-dependent mechanism. In contrast, we do not find evidence for a role of positive transcription elongation factor b (P-TEFb) in the establishment of latent infection in HPCs. Finally, we demonstrate that prostratin and suberoylanilide hydroxamic acid (SAHA), but not hexamethylene bisacetamide (HMBA) or 5-aza-2′-deoxycytidine (Aza-CdR), reactivate latent HIV-1 in HPCs. These findings illuminate the mechanisms through which latent infection can be established in HPCs and suggest common pathways through which latent virus could be reactivated in both HPCs and resting memory T cells to eliminate latent reservoirs of HIV-1.

Targeting IκB Proteins for HIV Latency Activation: the Role of Individual IκB and NF-κB Proteins

“…Indeed, other activators that work via the NF-B system and activators that employ other mechanisms, such as activators that act epigenetically, activate HIV in some model systems, but not in others (22,73). Some activators can even exhibit antagonistic effects for HIV activation in some systems and additive or synergistic effects in others (22).…”

HIV-1 infection of hematopoietic progenitor cells in vivo in humanized mice

“…Although it has been shown that some populations of progenitors can become infected with reporter viruses in vitro, 38 this has not been demonstrated with wild-type HIV nor in an animal model system. Recent work by others shows that HIV-1 DNA could not be detected in highly purified bone marrow CD341 cells derived from patients.…”

Latent human cytomegalovirus enhances HIV-1 infection in CD34+ progenitor cells

“…9,10 It remains unclear whether HCMV latent infection would affect the expression of HIV-1 restriction factors in CD34 1 cells. Therefore, to examine this, SAMHD1, APOBEC3G, Mx2, and tetherin gene expression was determined by qPCR in a time course experiment in PB-CD34 cells.…”

“…9,10 Latent HIV-1 exists in the proviral state in multiple hematopoietic progenitor cell subsets that is regulated by NF-kB activation. 10 As with other myeloid-lineage cells, however, CD34…”

“…Immunostaining for CD34, CD4, CD25, and intracellular p24 expression was performed on the cocultured cells at 48 hours PI and analyzed by flow cytometry. Reactivation of infected PB-CD34 cells was performed by adding GM-CSF (100 ng/mL) and tumor necrosis factor-a (TNF-a; 2.5 ng/mL) to the culture cells for 14 hours, 10 before being assessed by immunofluorescence staining using anti-gB (Novus Biologicals) and anti-p24 (DAKO) primary antibodies and antimouse immunoglobulin G2a (IgG2a) Alexa Fluor 488 and anti-mouse IgG1 Alexa Fluor 568 (Invitrogen), respectively. Images were acquired using Carl Zeiss LSM 700 confocal microscope using the 403 oil lens and ZEN software and analyzed by ImageJ software (http://imagej.nih.gov/ij).…”