Presentations

Abstract

Introduction:

HIV infection remains a major public health concern in the era of combined antiretroviral therapy (ART) and human immunodeficiency virus (HIV)-associated neurocognitive disorder (HAND), characterized by cognitive and memory impairment, continues to be prevalent. Microglia (Mg), the brain resident macrophages, can be activated by HIV infection and abnormal Mg activation has been believed as the driving force promoting HAND pathogenesis. However, the mechanisms underlying Mg activation in chronic HIV infected individuals remain much elusive. Metabolism dysregulation has inherent roles in immune responses in Mg. Whether HIV/HIV proteins could dysregulate metabolism process leading to Mg activation has not been explored before. Thus in this study, we aimed to explore the effects of HIV protein transactivator of transcription (TAT) on lipid metabolism in Mg using multiple in vitro and in vivo approaches.

Method:

BV2 microglial cells were cultured in vitro and primary Mg (PM) were isolated from new-born pups and cultured in vitro. The cells were then exposed to HIV-TAT with different doses (25 - 100 ng/ml) for different time periods (3 - 24 hours). Followed, the cells were collected for protein extraction. Also, HIV-TAT negative and positive mice were fed with doxycycline (DOX)-inducible food in vivo for three weeks for TAT expression. The mice were then sacrificed for the brain removal. Different brain regions were dissected followed by protein extraction. Western blots were performed to determine the levels of various molecules belonging to lipid metabolism pathways, including HMG-CoA reductase (HMGCR), SREBP-1, SREBP-2, and PLIN2. Meanwhile, the colocalization of lipid droplet (LD) with Mg were determined by double Immunofluorescence approach.

Results:

HIV-TAT increases the levels of HMGCR, SREBP-1, SREBP-2, and PLIN2 in both BV2 and PM in time-dependent and dose-dependent manners. HIV-TAT elevates LD levels in Mg and SREBP-2 levels in the brain hippocampus.

Conclusion:

HIV-TAT can dysregulate lipid metabolism in vitro and in vivo. More experiments have been planned to reveal whether HIV-TAT mediated lipid dysregulation is responsible for Mg activation.