Synergistic effects of HIV and fentanyl differentially remodel the synapto-proteome and disrupts synaptic excitatory and inhibitory receptors across brain regions

HIV-1 infection of the central nervous system is associated with reduction of neuronal density, abnormal connectivity and strong synaptic dysfunction, which are key features of HIV-associated neurocognitive impairment (NCI). Furthermore, co-occurring factors in people living with HIV (PLH), such as drug misuse can worsen these alterations. Synthetic opioids, particularly fentanyl – the most common drug used by PLH – disrupts the normal functioning of brain inhibitory networks impacting cognition. However, the combined effects of HIV and fentanyl on synapses are not fully understood.
In this study, we explored the individual and combined effects of HIV-1 infection and fentanyl daily administration (0.3 mg/kg) and overdose (160 mg/kg) using a mouse model with humanized immune system (NSG mice with peripheral immune reconstitution) (3 Female 22 weeks old mice per group; 1. Control, 2. HIV-1(+), 3. fentanyl only exposure, 4. Fentanyl and HIV-1(+)). To determine potential synaptic changes, synaptosomes from the middle pre-frontal cortex (mPFC), striatum (ST) and hippocampus (HP), were isolated, and analyzed by label-free LC (LC-MSM) proteomic analysis. We also performed electrophysiological recordings from microtransplanted native mice synapses to determine functional changes of excitatory glutamate AMPA-type receptors and inhibitory GABAA receptors’ functionality.
Our findings indicate that HIV-1 and fentanyl each alter overlapping synaptic pathways at the protein level, but their combination produces a distinct proteomic signature. Principal component analysis using the 50 most significantly differentially expressed genes across groups (ANOVA p-value <0.0001), showed a clear separation between control and HIV-Fentanyl combination along the PC2 component while PC1 separates the control and the individual HIV and Fentanyl treated groups. Gene-ontology enrichment revealed mitochondrial-related genes as the most affected. Furthermore, in synaptic function there is a synergistic effect of HIV-1 infection and fentanyl exposure, with a drastic reduction of GABAergic and glutamatergic activity across all brain regions. In conclusion, HIV and Fentanyl-chronic exposure showed a synergistic effect exhibiting mitochondrial pathway dysregulation and synaptic dysfunction of GABAAR and AMPA receptors. Understanding these synaptic alterations caused by the combination of HIV-1 and Fentanyl in mice is a necessary step for translating these findings to human research in PLH with polydrug misuse.