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

Treatment with latency-reversing agents (LRAs) alone has been ineffective in reducing HIV-1 reservoirs in persons with HIV-1 (PWH) on antiretroviral therapy (ART), due to inefficiencies in reservoir reactivation and adaptive immune responses. However, NK cells that are activated with cytokines may be able to target HIV-1 reservoirs more efficiently. To study the therapeutic potential of NK cells, we expanded blood NK cells from multiple donors ex vivo into CD56brightCD16+ "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. eNK cells can also kill HIV-infected CD4 T cells via antibody dependent cell-mediated cytotoxicity (ADCC) using broadly neutralizing antibodies against HIV-1 Env gp120/gp41. Importantly, eNK cells from PWH 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 detected by declines in proviral load, inducible HIV-1 mRNA, and virus release. Adoptive immunotherapy with eNK cells is therefore a promising approach to reduce the latent HIV-1 reservoir in PWH when combined with LRA treatment. Author SummarySuccessful antiretroviral therapy (ART) eliminates progression to AIDS by reducing HIV to nearly indetectable levels by routine clinical measurements of blood samples. However, more sensitive DNA and RNA measurements show that most persons on ART retain a reservoir of long lived latently infected cells, which remain undetected by the immune system while no HIV is being produced. In nearly all cases, ART interruption results in a rebound of HIV production and spread, requiring an immediate return to ART. Currently the goal of HIV eradication is to achieve a "functional cure", where HIV reservoirs are reduced to the point where ART can be interrupted indefinitely, and low levels of infected cells remaining can be controlled by the immune system. Our eradication strategy combines HIV latency-reversing agents (LRAs), ex vivo expansion of natural killer (NK) cells, and enhancement of specificity and killing of infected cells with broadly neutralizing antibodies against HIV. In this study, we have demonstrated that NK cells from person living with HIV can be isolated and expanded ex vivo into "eNK" cells that kill HIV-infected cells without killing uninfected cells, especially when broadly neutralizing antibodies are present, and can significantly reduce HIV reservoirs after LRA treatment.