ELUCIDATING THE ROLE OF NATURAL KILLER CELLS IN HIV CONTROL AND EVALUATION OF A BISPECIFIC ANTIBODY TO ENHANCE THEIR FUNCTION

Abstract

The human immunodeficiency virus (HIV) causes a chronic infection that disrupts the immune system and, in the absence of treatment, can lead to acquired immunodeficiency syndrome (AIDS). The currently available antiretroviral treatment (ART) can suppress viremia to undetectable levels, restore immune cell function, and reduce the mortality and morbidity associated with the infection, thereby decreasing the risk of transmission. However, ART is unable to completely eliminate the virus from the cells, primarily due to the formation of viral reservoirs that allow HIV to remain in a latent state, rendering invisible to the action of ART and the immune system. Consequently, upon treatment interruption, the viral load increases again to detectable levels within a few weeks. Therefore, individuals with HIV require lifelong administration of ART. For this reason, it is essential to develop new therapeutic strategies aimed at achieving HIV cure. The development of new therapies requires a deep understanding of the mechanisms that control HIV as well as the development of approaches that enhance immune responses to eliminate the virus. To date, six cases of HIV cure have been described, all through hematopoietic stem cell transplants harboring mutations in the CCR5 gene, which confers resistance to HIV infection from R5-tropic virus, in cancer patients. In addition to these cases, there are also the so-called elite controllers, individuals that exhibit the exceptional ability to control HIV infection for prolonged periods in the absence of ART. Furthermore, Natural Killer (NK) cells are promising candidates for the development of immunotherapies against HIV due to their potent immunological activity. The present doctoral thesis describes the differential phenotype expressed by NK cells in elite controllers compared to other groups of people living with HIV. Here, we show that these individuals present higher frequencies of memory NK cells with a particular phenotype, including the expression of the inhibitory marker NKG2A, and that they can mediate robust ADCC responses against infected cells. Additionally, these cells exhibit a unique transcriptional profile characterized by the upregulation of genes involved in the metabolism, migration, effector and antiviral responses of these cells. Secondly, the use of a bispecific antibody to simultaneously target HIV-infected cells and NK cells has been evaluated both in vitro and in vivo in a humanized mouse model of HIV infection. The results show that the bispecific antibody enhances the action of NK cells in eliminating HIV+ cells in various contexts of viral infection. However, preclinical evaluation showed a reduction in the total NK cell population following sustained antibody administration, which was associated with poor virological HIV control after ART interruption. In conclusion, the present doctoral thesis describes a population of NK cells with potent cytotoxic responses against HIV-infected cells in elite controllers, with implications for the design of new functional cure strategies aimed at eliminating viral reservoirs, and highlights the potential of a bispecific antibody for the development of novel immunotherapies targeting NK cells for HIV control.

Date of Award	27 Sept 2024
Original language	English
Supervisor	Maria Jose Buzon Gomez (Director)