614 – Differential Effects of CB2 Agonism on HIV Replication and Inflammatory Activation in Myeloid Cells

Background

Evidence indicates that brain-resident myeloid cells, including perivascular macrophages and microglia, provide a reservoir for HIV infection in the central nervous system (CNS). Data also suggest that the inflammatory activity of these cells is associated with HIV-associated cognitive impairment. We investigated whether cannabinoid receptor (CB) 2 (CB₂), an immunomodulatory receptor expressed in myeloid cells, regulates viral replication and inflammation in HIV-infected macrophages and microglia. 

Methods

In primary human monocyte-derived macrophages (hMDM) and human induced pluripotent stem cell-derived microglia (iMg), changes in gene expression and cytokine/chemokine secretion following infection with 1 ng/mL HIV_ADA were evaluated using RNA sequencing and Bio-Plex^® 48-Plex Pro Human Cytokine Screening Panel, respectively. To mitigate the potential dual-receptor activity at both CB₁ and CB₂, cultures were exposed to the CB₂-specific JWH-133, a synthetic cannabinoid (Ki, 3.4 nM; >200-fold selectivity for CB₂ over CB₁) during the 24-h initial inoculation with HIV, and cultures were maintained for 9 days post-infection (DPI). To confirm that the observed effects were CB₂-specific, SR-144,528, a CB₂-selective inverse agonist (Ki, 0.6 nM; >600-fold selectivity for CB₂ over CB₁) was added 1 h prior to JWH-133 to ensure saturation of receptors. 

Results

JWH-133 reduced HIV replication in primary hMDM and iMg at differing doses and timepoints (~50% reduction on DPI7 with 10 µM JWH-133 in hMDM, ~35% on DPI5 with 1 µM JWH-133 in iMg); these effects were abrogated with SR-144,528 pretreatment. In both hMDM and iMg, the effect of JWH-133 corresponded to the basal expression level of CNR2, which encodes CB₂, and related endocannabinoid transcripts in each cell type. JWH-133 broadly reduced cytokine release from HIV-infected hMDM but not iMg. RNA-seq revealed that CB₂ agonism primarily altered interferon and integrated stress response pathways in hMDM while altering homeostatic pathways, including synapse maintenance and phagocytosis, in iMg. Further analyses in iMg revealed that NLRP3 inflammasome activation, but not priming, was reduced by CB₂ activation, which did not inhibit HIV-induced NF-kB activation.

Conclusions

This study identifies key differences in CB₂ response between myeloid lineage cell types and implicates CB₂-specific agonists as promising candidates for the regulation of HIV-associated neuroinflammation.

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