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

Greater fatigue, disturbed sleep, persistent memory problems, and reduced CD4+ T cell and B cell percentages in adults with a history of methamphetamine dependence

Methamphetamine (MA) dependence is associated with immunotoxicity and high rates of neuropsychiatric impairments that persist into remission. Although there are currently no FDA-approved pharmacotherapies for MA use disorders, preclinical and clinical studies are beginning to test interventions that directly impact immune signaling. This study was conducted to investigate the relative contribution of immune cell function to the neuropsychiatric sequelae associated with MA dependence and remission. Participants were enrolled into the following study groups: i) control (CTL) group (n = 62): adults with no lifetime history of dependence on any substance other than nicotine or caffeine; and ii) MA group (n = 98) [MA-remission group (n = 55): adults in remission ≥1 month and ≤ 6 months and MA-active group (n = 43): adults actively using MA and meeting criteria for MA dependence]. Participants completed a clinical interview, urine drug analysis, blood sample collection, and questionnaires. Peripheral blood mononuclear cells were analyzed by flow cytometry. Results suggest that early remission from MA dependence is associated with increased fatigue and persistent sleep and prospective and retrospective memory problems, along with reduced B and CD4+ T cell percentages, compared to the CTL group. Preliminary findings support the hypothesis that the immune system modulates the sleep impairments associated with drug actions and provide implications for future research studies and treatment approaches.

Oyster powder supplementation enhances immune function in mice partly through modulating the gut microbiota and arginine metabolism

Oysters are well-known for their health benefits such as immuno-modulatory functions. The intestinal microbiome serves as a key mediator between diet and immune regulation. This study aimed to investigate whether oyster consumption could alleviate cyclophosphamide (Cy)-induced immunosuppression by promoting intestinal homeostasis. In mice treated with Cy, a significant decrease in immune cells and cytokines was observed. In contrast, mice supplemented with oyster powder demonstrated elevated numbers of immune cells in the spleen and small intestine, as well as enhanced serum production of IL-1β, IL-2, TNF-α, and IFN-γ. Furthermore, oyster consumption improved the composition of the gut microbiota by promoting beneficial bacteria and inhibiting harmful ones. Metabolomics analysis revealed that oyster powder treatment significantly enhanced the arginine biosynthesis pathway, and further analysis found that the consumption of oysters led to increased arginine levels. Correlation analysis showed a significant positive correlation between L-arginine and immune-related markers. Collectively, these findings suggest that oyster consumption may enhance immunity by modulating the gut microbiota and boosting arginine biosynthesis pathways. Dietary oyster consumption could be an effective strategy to support immune health.

The interaction between central and peripheral immune systems in methamphetamine use disorder: current status and future directions

Methamphetamine (METH) use disorder (MUD) is characterized by compulsive drug-seeking behavior and substantial neurotoxicity, posing a considerable burden on individuals and society. Traditionally perceived as a localized central nervous system disorder, recent preclinical and clinical studies have elucidated that MUD is a multifaceted disorder influenced by various biological systems, particularly the immune system. Emerging evidence suggests that both central and peripheral immune responses play a crucial role in the initiation and persistence of MUD. Conceptualizing it as a systemic immune process prompts significant inquiries regarding the mechanisms of communication between peripheral and central compartments. Also, whether this intercommunication could serve as diagnostic biomarkers or therapeutic targets. This review begins by offering an overview of mechanistic studies pertaining to the neuroimmune and peripheral immune systems. Finally, future directions are suggested through the integration of innovative technologies and multidimensional data to promote the translation of basic mechanistic research into clinical diagnostic and therapeutic interventions.

Single-cell RNA-seq Reveals the Inhibitory Effect of Methamphetamine on Liver Immunity with the Involvement of Dopamine Receptor D1

Methamphetamine (METH) is a highly addictive psychostimulant that causes physical and psychological damage and immune system disorder, especially in the liver which contains a significant number of immune cells. Dopamine, a key neurotransmitter in METH addiction and immune regulation, plays a crucial role in this process. Here, we developed a chronic METH administration model and conducted single-cell RNA sequencing (scRNA-seq) to investigate the effect of METH on liver immune cells and the involvement of dopamine receptor D1 (DRD1). Our findings reveal that chronic exposure to METH induces immune cell identity shifts from IFITM3+ macrophage (Mac) and CCL5+ Mac to CD14+ Mac, as well as from FYN+CD4+ T effector (Teff), CD8+ T, and natural killer T (NKT) to FOS+CD4+ T and RORα+ group 2 innate lymphoid cell (ILC2), along with the suppression of multiple functional immune pathways. DRD1 is implicated in regulating certain pathways and identity shifts among the hepatic immune cells. Our results provide valuable insights into the development of targeted therapies to mitigate METH-induced immune impairment.

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

The dopamine transporter (DAT) is one of the key regulators of dopamine (DA) signaling in the central nervous system (CNS) and in the periphery. Recent reports in a model of Parkinson's disease (PD) have shown that dopamine neuronal loss in the CNS impacts the expression of DAT in peripheral immune cells. The mechanism underlying this connection is still unclear but could be illuminated with sensitive and high-throughput detection of DAT-expressing immune cells in the circulation. Herein, we have developed fluorescently labeled ligands (FLL) that bind to surface-expressing DAT with high affinity and selectivity. The diSulfoCy5-FLL (GC04-38) was utilized to label DAT in human and mouse peripheral blood mononuclear cells (PBMCs) that were analyzed via flow cytometry. Selective labeling was validated using DAT KO mouse PBMCs. Our studies provide an efficient and highly sensitive method using this novel DAT-selective FLL to advance our fundamental understanding of DAT expression and activity in PBMCs in health and disease and as a potential peripheral biomarker.

Immunity on ice: The impact of methamphetamine on peripheral immunity

Methamphetamine (METH) regulation of the dopamine transporter (DAT) and central nervous system (CNS) dopamine transmission have been extensively studied. However, our understanding of how METH influences neuroimmune communication and innate and adaptive immunity is still developing. Recent studies have shed light on the bidirectional communication between the CNS and the peripheral immune system. They have established a link between CNS dopamine levels, dopamine neuronal activity, and peripheral immunity. Akin to dopamine neurons in the CNS, a majority of peripheral immune cells also express DAT, implying that in addition to their effect in the CNS, DAT ligands such as methamphetamine may have a role in modulating peripheral immunity. For example, by directly influencing DAT-expressing peripheral immune cells and thus peripheral immunity, METH can trigger a feed-forward cascade that impacts the bidirectional communication between the CNS and peripheral immune system. In this review, we aim to discuss the current understanding of how METH modulates both innate and adaptive immunity and identify areas where knowledge gaps exist. These gaps will then be considered in guiding future research directions.