HIV-associated neurocognitive disorders (HAND) persist despite the advent of antiretroviral therapy (ART), suggesting underlying systemic and central nervous system (CNS) inflammatory mechanisms. The endogenous cannabinoid receptors 1 and 2 (CB1 and CB2) modulate inflammatory gene expression and play an important role in maintaining neuronal homeostasis. Cannabis use is disproportionately high among people with HIV (PWH) and may provide a neuroprotective effect for those on ART due to its anti-inflammatory properties. However, expression profiles of CB1 and CB2 in the brains of PWH on ART with HAND have not been reported. In this study, biochemical and immunohistochemical analyses were performed to determine CB1 and CB2 expression in brain specimens of HAND donors. Immunoblot revealed CB1 and CB2 were differentially expressed in frontal cortices from HAND brains compared to neurocognitively unimpaired (NUI) brains from PWH. CB1 expression levels negatively correlated with memory and information processing speed. CB1 was primarily localized to neuronal soma in HAND brains versus a more punctate distribution on neuronal processes of NUI brains. CB1 expression was increased in cells with glial morphology and showed increased colocalization with an astroglial marker. These results suggest that targeting the endocannabinoid system may be a potential therapeutic strategy for HAND.

There is a significant overlap between HIV infection and substance use disorders. Dopamine (DA) is the most abundantly upregulated neurotransmitter in Methamphetamine abuse, with receptors (DRD1-5) that are expressed by neurons as well as by a large diversity of cell types, including innate immune cells that are targets of HIV infection, making them responsive to the hyperdopaminergic environment that is characteristic of stimulant drugs. Therefore, the presence of high levels of dopamine may affect the pathogenesis of HIV, particularly in the brain. The stimulation of HIV-latently infected U1 promonocytes with DA significantly increased viral p24 levels in the supernatant at 24 hrs, suggesting effects on activation and replication. Using selective agonists to different DRDs, we found that DRD1 played a major role in activating viral transcription, followed by DRD4, which increased p24 with a slower kinetic. Transcriptome and systems biology analyses led to the identification of a cluster of genes responsive to DA, where S100A8 and S100A9 were most significantly correlated with the early increase of p24 levels following DA stimulation. Conversely, DA increased the expression of these genes’ transcripts at the protein level, respectively MRP8 and MRP14, which form a complex also known as Calprotectin. Interestingly, MRP8/14 was able to stimulate HIV transcription in latent U1 cells, and this occurred via binding to the receptor for advanced glycosylation end-product (RAGE). Using selective agonists, both DRD1 and DRD4 increased MRP8/14 on the surface and in the cytoplasm, as well as secreted in the supernatants. On the other hand, while DRD1/5 did not affect the expression of RAGE, DRD4 stimulation caused its downregulation, offering a mechanistic for the delayed effect via DRD4 on p24 increase. To cross-validate MRP8/14 as a DA signature with biomarker value, we tested its expression in HIV+ Meth users’ brains and peripheral cells. MRP8/14+ cells were more frequently identified in mesolimbic areas such as basal ganglia of HIV+ Meth+ cases compared to HIV+ non-Meth users or to controls. Likewise, MRP8/14+ CD11b+ monocytes were more frequent in HIV+ Meth users, particularly in participants with detectable viral load in the CSF. Overall, our results suggest that the MRP8 and MRP14 complex may serve as a signature to distinguish subjects using addictive substances in the context of HIV, and that this may play a role in aggravating HIV pathology by promoting viral replication in people with HIV who use Meth.