Reduction of the HIV-1 reservoir in T cells from people with HIV-1 on suppressive antiretroviral therapy using expanded natural killer cells

Treatment with latency-reversing agents (LRAs) alone has been ineffective in reducing HIV-1 reservoirs in people living with HIV-1 (PLWH) who are on antiretroviral therapy (ART), due to inefficiencies in reservoir reactivation and adaptive immune responses. However, NK cells activated with cytokines may be able to target HIV-1 reservoirs more effectively. To explore the therapeutic potential of NK cells, we expanded blood NK cells from multiple donors <i>ex vivo</i> into CD56^bright CD16⁺ "eNK" cells using artificial antigen-presenting cells (aAPCs) expressing membrane-bound IL21. eNK cells express multiple activating receptors and are highly cytotoxic against specific target cells. They can also kill HIV-infected CD4+ T cells via antibody-dependent cell-mediated cytotoxicity (ADCC) using broadly neutralizing antibodies (bNAbs) against HIV-1 Env gp120/gp41. Notably, eNK cells from PLWH on ART efficiently killed autologous HIV-1+ T cells reactivated by a combination of vorinostat (SAHA) and IL-15 or an IL-15 superagonist (N-803), as evidenced by declines in proviral load, inducible HIV-1 mRNA, and virus release. Adoptive immunotherapy with eNK cells combined with LRA treatment thus presents a promising strategy to reduce the latent HIV-1 reservoir in PLWH.IMPORTANCEAntiretroviral therapy (ART) lowers HIV levels in the blood to nearly undetectable amounts, but stopping therapy almost always leads to HIV rebounding in the bloodstream. DNA and RNA tests show that most people living with HIV (PLWH) on ART retain long-lasting HIV reservoirs that remain hidden from the immune system when no HIV is being produced. Eradicating HIV might look like "drug-free remission," where HIV reservoirs are kept under control by the immune system even if ART is stopped indefinitely. Current strategies for this potential eradication include using HIV latency-reversing agents (LRAs), <i>ex vivo</i> expansion of natural killer (NK) cells, and improving the ability to kill infected cells with broadly neutralizing antibodies against HIV. Here, we demonstrate that NK cells from PLWH can be expanded outside the body into "eNK" cells that specifically attack HIV-infected cells without harming uninfected ones, significantly reducing HIV reservoirs <i>in vitro</i> after LRA treatment.