Dopamine May Exacerbate Neuroinflammation in the Context of HIV by Driving Inflammatory Phenotypes in Macrophages

Abstract

Globally, there are around 38 million people living with HIV (PLWH). Treatment with anti‐retroviral therapy (ART) can suppress HIV replication and improve the length and quality of life, but chronic infection and ART treatment has resulted in the development of a variety of new co‐morbidities. Among these are the constellation of neuropathological, behavioral, cognitive and motor symptoms collectively known as neuroHIV. These symptoms are found in approximately 50% of the infected population, and multiple lines of evidence indicate that neuroHIV is primarily mediated by chronic CNS infection and inflammatory response in CNS myeloid populations such as macrophages and microglia. In many PLWH, these inflammatory conditions can be exacerbated by substance use disorders, which are highly comorbid with HIV infection and disproportionately common in HIV‐infected populations. Substance use disorders of all types are a major risk factor for the development of neuroHIV, suggesting a common mechanism by which substances of abuse interact with HIV to promote inflammation. All addictive substances increase extracellular dopamine in the CNS and our previous data show that dopamine promotes an inflammatory phenotype in human macrophages. Thus, we hypothesize that exposure to dopamine concentrations (10‐6M) induced by stimulant use will more robustly increase inflammation in HIV‐infected human monocyte‐derived macrophages (MDM) than in uninfected MDM. To test this, uninfected and HIV‐infected human MDM were treated with dopamine and changes in inflammatory profiles were assessed by measuring NF‐κB nuclear translocation using high content imaging and quantifying cytokine production by AlphaLISA analysis. Dopamine significantly increased the production of the inflammatory cytokines IL‐6 and IL‐1β, and these were specifically mediated via dopamine receptors and the activation of NF‐κB. These findings correlate with expression of dopaminergic receptors and nod‐like receptor (NLR) inflammasome transcripts and were altered in the presence of HIV infection. We also found that baseline macrophage activation could be attributed to culture medium type. Overall, these studies provide a broader understanding of the immunological role of dopamine, particularly in the development of neuroHIV and may suggest a potential mechanism for further pharmacological investigation to target HIV infection.