DAT18-01. Abuse of stimulants, such as cocaine and methamphetamine, results in a variety of serious health conditions, and drug abusers have poorer health outcomes than non-drug using, demographically similar populations. In the central nervous system, the use of stimulants induces neuroinflammation through a greater release of inflammatory factors and recruitment of additional leukocytes. This predisposes drug abusers to a higher incidence of neuropsychiatric, cerebrovascular and motor disorders, and can also exacerbate the neuropathogenic impact of infection with HIV, HCV and a number of bacterial pathogens. The precise pathways by which stimulants mediate these effects are not clear, but many of these effects could be induced by drug-associated activation of specific inflammatory triggers such as NF- kB. However, direct links between stimulants and these neuroinflammatory mechanisms have not been described. The premise of this proposal is that dopamine acts as a common mechanism by which stimulants activate myeloid cell NF-kB and thereby initiate or exacerbate neuroinflammation. Use of all stimulants acutely increases CNS dopamine levels, exposing cells in dopamine-rich brain regions to aberrantly high dopamine concentrations. Among these cell populations are myeloid cells, such as perivascular macrophages and microglia, which are the primary immune cells in the CNS. Our published research shows that acute exposure to elevated dopamine increases myeloid production of inflammatory cytokines, such as IL-1b, IL-6, CXCL8 and CXCL10. Our preliminary data suggest that dopamine acts by activating the NF- kB pathway and priming the NLRP3 inflammasome, a complex that regulates the release of IL-1b, a master regulator of inflammation. The specific pathways mediating this effect are not clear, and therefore these studies will generate detailed information about specific dopamine receptors, gene and protein targets mediating dopamine activation of NF-kB and NLRP3 in human macrophages. Determining the specific signaling mechanisms and genes involved in dopamine induced increases in NF-kB activity will indicate pathways that could be targeted to ameliorate the neuroinflammatory effects of stimulant use, significantly improving the long-term health outcomes of stimulant users. The data developed in this proposal will serve as a basis for future projects examining the modulation of the myeloid dopaminergic system as a therapeutic strategy for limiting the increased incidence of neurologic disease and inflammation associated with drug abuse. These projects will examine both novel effectors and the repurposing of existing dopaminergic therapeutics to ameliorate inflammation in the stimulant abusing population.
Abuse of cocaine or methamphetamine increases the risk of developing neuroinflammation and subsequent neuropathology, but the specific mechanisms by which this occurs remain unclear. These drugs act by acutely increasing extracellular dopamine in the brain, which our preliminary data show increases the activity of the inflammatory pathways in human macrophages, thereby initiating or exacerbating neuroinflammation. This study will define the specific mechanisms and genes that enable dopamine activate these inflammatory cascades, providing potential therapeutic targets to better control neuroinflammation in stimulant abusers.
