Methamphetamine induces a low dopamine transporter expressing state without altering the total number of peripheral immune cells

Abstract

Methamphetamine is a widely abused psychostimulant and one of the main targets of dopamine transporter (DAT). Methamphetamine reduces DAT‐mediated dopamine uptake and stimulates dopamine efflux leading to increased synaptic dopamine levels many folds above baseline. Methamphetamine also targets DAT‐expressing peripheral immune cells, reduces wound healing and increases infection susceptibility. Peripheral immune cells such as myeloid cells, B cells and T cells express DAT. DAT activity on monocytes and macrophages exhibits immune suppressive properties via an autocrine paracrine mechanism, where deletion or inhibition of DAT activity increases inflammatory responses. In this study, utilizing a mouse model of daily single dose of methamphetamine administration, we investigated the impact of the drug on DAT expression in peripheral immune cells. We found in methamphetamine‐treated mice that DAT expression was down‐regulated in most of the innate and adaptive immune cells. Methamphetamine did not increase or decrease the total number of innate and adaptive immune cells but changed their immunophenotype to low‐DAT‐expressing phenotype. Moreover, serum cytokine distributions were altered in methamphetamine‐treated mice. Therefore, resembling its effect in the CNS, in the periphery, methamphetamine regulates DAT expression on peripheral immune cell subsets, potentially describing methamphetamine regulation of peripheral immunity.

Development of a Fluorescently Labeled Ligand for Rapid Detection of DAT in Human and Mouse Peripheral Blood Monocytes

“…Since a small subset of human PBMCs (∼4−5%) express NET, a parallel set of PBMCs were incubated with GC04-38 in the presence of a NET blocker, desipramine (DMI) (Figure 3H). Compared to the fluorescent signal obtained in cells treated with GC04-38 alone (Figure 3F), NET blockade (DMI pretreatment) produced a 3−5% decrease in GC04-38 fluorescent signal (Figure 3G), which is consistent with recent reports 9,12 showing a small percentage of circulating PBMCs expressing NET. 9,12 To further assess the specificity of GC04-38 for DAT, an additional set of PBMCs were incubated in parallel with both DMI and 100 mM JJC8-087, the nonfluorescent parent compound (Figure 1B,C) of GC04-38.…”

“…Compared to the fluorescent signal obtained in cells treated with GC04-38 alone (Figure 3F), NET blockade (DMI pretreatment) produced a 3−5% decrease in GC04-38 fluorescent signal (Figure 3G), which is consistent with recent reports 9,12 showing a small percentage of circulating PBMCs expressing NET. 9,12 To further assess the specificity of GC04-38 for DAT, an additional set of PBMCs were incubated in parallel with both DMI and 100 mM JJC8-087, the nonfluorescent parent compound (Figure 1B,C) of GC04-38. Consistent with data shown in the rat striatal tissue (Table 1), the JJC8-087 pretreatment abolished the fluorescent GC04-38 signal in PBMCs (Figure 3H,J).…”

“…DAT is expressed on human and murine immune cells, − ,,, is functional, and is detected via immunostaining, confocal microscopy, and flow cytometry , using the MAB369 antibody against the N-terminus of DAT . To our knowledge, conventional flow cytometry is the most used high-throughput assay to identify DAT-expressing immune cells in blood circulation.…”

“…Prior studies employed anti-DAT antibody staining followed by flow cytometric analysis − to detect DAT-expressing immune cells in the peripheral circulation. MAB369 is a widely used primary antibody that effectively and reproducibly recognizes the intracellular N-terminal domain of DAT in permeabilized preparations.…”

“…In the CNS, this member of the reuptake-1 monoamine transporters (MATs) clears extracellular dopamine by transporting it into the cell for storage in vesicles. , Recent studies have shown that peripheral immune cells such as monocytes and macrophages express DAT and norepinephrine transporter (NET). The bidirectional communication between the CNS and the peripheral immune system is a well-established concept showing changes in dopamine levels in the CNS, and the activity of dopamine neurons regulates peripheral immune responses. − Since many peripheral immune cells express DAT, by directly influencing DAT-expressing peripheral immune cells and thus peripheral immunity, DAT ligands can trigger a feed-forward cascade that impacts the bidirectional communication between the CNS and peripheral immune systems . For example, in PD DAT, a classic CNS biomarker is increased in peripheral blood mononuclear cells (PBMCs) of drug-naïve PD patients, whereas there is a decrease of this protein in the CNS .…”