Immunometabolic reprogramming during suppressive HIV-1 infection

Abstract

Since the implementation of antiretroviral therapy (ART), infection with human immunodeficiency virus type-1 (HIV-1) has been transformed into a chronic lifelong condition. The main obstacle for a HIV-1 cure is the persistence of latently infected cells in viral reservoirs. The viral endurance can instigate detrimental changes on the function and activity of immune cells, creating a chronic inflammatory environment in people living with HIV-1 (PLWH) on successful long-term suppressive antiretroviral therapy (PLWHART). The continuous activation of immune cells may lead to an earlier onset of age-related diseases. Immunometabolism is an emerging field that studies how metabolic reprogramming has an impact on the activation, differentiation, and function of immune cells. Given that these underlying processes are likely to contribute to chronic inflammation in PLWH, the overall aim of this thesis was to evaluate how immunometabolism is reprogrammed during “controlled” HIV-1 infection, either by ART in PLWHART or in PLWH with natural control of infection, elite controllers (PLWHEC).

In paper I, we integrated proteomic and transcriptomic data to investigate features distinct to the PLWHEC phenotype in a male cohort. We identified dysregulated hypoxia inducible factor (HIF) signalling and altered metabolism as unique characteristics of the male PLWHEC phenotype. As controlled HIV-1 infection still induce changes in the immune system we aimed to compare differences in the immune phenotype between PLWHEC and PLWHART and its relation to HIV-1 persistence in paper II. We identified a unique phenotype of decreased CCR6 expression on CD4+ and CD8+ T cells in PLWHEC compared to PLWHART and healthy controls (HC). Additionally, the CD4+CCR6+ cells exhibited a proteomic profile indicative of increased sensitivity towards cell death mechanisms in PLWHEC compared to PLWHART. A reduced proportion of integrated HIV-1 DNA in the reservoir of PLWHEC was found, although no difference in the amount of intact provirus. Continuing our evaluation of differences between PLWHEC and PLWHART we performed metabolo-transcriptomic analysis to understand and infer changes on a multisystem level in paper III. We detected a system level metabolic aberration mainly revolving around OXPHOS in PLWHART compared to PLWHEC. Using pharmacological modulation, we identified how this dysregulation of OXPHOS possibly affects HIV-1 reservoir dynamics and the immune senescence profile. Furthermore, to understand how HIV-1 chronicity affects long-lasting metabolic flexibility and adaptation we conducted plasma metabolomics to understand alterations during suppressive ART in a Swedish cohort in paper IV. We also aimed to characterize the cell populations that mainly contribute to changes in the metabolic environment. We detected aberrant energy metabolism in PLWHART, mainly revolving around the tricarboxylic acid cycle and amino acid synthesis. Cell-type specific evaluation showed that the main metabolic alterations occurred on monocytic cell populations, and that PLWHART exhibited dysregulated chemokine receptor expression of CCR2, CCR5, and CX3CR1 on myeloid cell lineages. In paper V, we wanted to evaluate if the altered metabolic environment was consistent on a global scale using two cohorts from low and middle-income countries (namely, Cameroon and India) using plasma metabolomics. We detected a dysregulation of amino acid metabolism and a switch towards glutaminolysis during long-term suppressive ART.

In summary, the research covered in this thesis illuminates the importance of metabolic reprogramming during HIV-1 persistence in PLWH with controlled infection.