Effect of the Use of Galectin-9 and Blockade of the TIM-3 Receptor in the Latent Cellular Reservoir of HIV-1

Abstract

Reactivation of latent HIV-1 is a necessary step for the purging of the viral reservoir, although it does not seem to be enough. The stimulation of HIV-1 specific cytotoxic T lymphocytes (CTL) may be just as essential for this purpose. In this study, we aimed to show the effect of galectin-9 (Gal-9), known to revert HIV-1 latency, in combination with the blockade of TIM-3, a natural receptor for Gal-9 and an exhaustion marker. We confirmed the ability of Gal-9 to reactivate latent HIV-1 in Jurkat-LAT-GFP cells, as well as in an IL-7-based cellular model. This reactivation was not mediated via the TIM-3 receptor, but rather by the recognition of the Gal-9 of a specific oligosaccharide pattern of resting memory CD4+ T cells’ surfaces. The potency of Gal-9 in inducing transcription of latent HIV-1 was equal to or greater than that of other latency-reversing agents (LRA). Furthermore, the combination of Gal-9 with other LRA did not show synergistic effects in the reactivation of the latent virus. To evaluate the impact of TIM-3 inhibition on the CTL-response, different co-culture experiments with CD4+T, CD8+ T, and NK cells were performed. Our data showed that blocking TIM-3 was associated with control of viral replication in both in vitro and ex vivo models in cells from PLWH on antiretroviral therapy. A joint strategy of the use of Gal-9 to reactivate latent HIV-1 and the inhibition of TIM-3 to enhance the HIV-1 CTL specific-response was associated with control of the replication of the virus that was being reactivated, thus potentially contributing to the elimination of the viral reservoir. Our results place this strategy as a promising approach to be tested in future studies. Reactivation of latent-HIV-1 by Gal-9 and reinvigoration of CD8+ T cells by TIM-3 blockade could be used separately or in combination. Importance HIV-1 infection is a health problem of enormous importance that still causes significant mortality. Antiretroviral treatment (ART) has demonstrated efficacy in the control of HIV-1 replication, decreasing the morbidity and mortality of the infection, but it cannot eradicate the virus. In our work, we tested a protein, galectin-9 (Gal-9), an HIV-1 latency-reversing agent, using an in vitro cellular model of latency and in cells from people living with HIV-1 (PLWH) on antiretroviral therapy. Our results confirmed the potential role of Gal-9 as a molecule with a potent HIV-1 reactivation capacity. More importantly, using a monoclonal antibody against T cell immunoglobulin and the mucin domain-containing molecule 3 (TIM-3) receptor we were able to enhance the HIV-1 cytotoxic T lymphocytes (CTL) specific response to eliminate the CD4+ T cells in which the virus had been reactivated. When used together, i.e., Gal-9 and TIM-3 blockade, control of the replication of HIV-1 was observed, suggesting a decrease in the cellular reservoir.

Immune checkpoint blockade in HIV

“… 99 Furthermore a recent report demonstrated the ability of Gal-9 to reactivate latent HIV-1 in a jurkat T-cell line. 52 This finding is consistent with a recent study showing Gal-9 shedding by neutrophils can activate T cells via binding to CD44 which leads to T cell activation in PWH. 100 CD155 is a ligand of the TIM-3 receptor and was shown to be upregulated on CD4+ Tfh cells that reside in the lymph node, a major site of HIV persistence.…”

“…In some individuals, this could be reduced upon ART and blocking TIM-3 interaction resulted in reinvigoration and restoration of CD8 effector functions ex vivo 49 implying that neutralizing TIM-3 may have a role in approaches to eliminate the HIV reservoir. 52 …”

Tim-3 Blockade Elicits Potent Anti-Multiple Myeloma Immunity of Natural Killer Cells

“…When Tim-3 on NK cells bind to its ligands, its function of secreting cytokines and killing target cells is diminished (20)(21)(22). It has been assumed that the Tim-3-Galectin-9 pathway plays an important role in regulating tumor cells escaping from immune surveillance (23,24). In our study, of all the Tim-3 ligands, only CEACAM1 was expressed on NK-92 cells (about 70%).…”

The HIV-1 accessory protein Nef increases surface expression of the checkpoint receptor Tim-3 in infected CD4+ T cells

“…Specifically, Tim-3 can interact with Gal-9 via the N-terminal IgV domain, which can trigger apoptosis in T helper type 1 immune cells ( 20 , 21 , 27 ). A recent report demonstrated that blocking Tim-3 could enhance the response of cytotoxic T lymphocytes to purge the latent reservoir in Gal-9-treated CD4 + T cells, implying that neutralizing Tim-3 may be an effective approach to eliminate the virus reservoir ( 75 ). Further studies will define how Nef inhibitors can be used to block Tim-3 upregulation to potentially aid in elimination of the viral reservoir.…”