Methamphetamine alters T cell cycle entry and progression: role in immune dysfunction

Single-cell sequencing reveals the heterogeneity of immune landscape in drug users with HIV infection

BACKGROUND

Injection drug use (IDU) leads to immune system dysfunction, thereby increasing the risk of opportunistic infection. There is a critical need to reveal the role of IDU in the immunopathogenesis of HIV infection.

METHODS

We performed single-cell RNA sequencing (scRNA-seq) on peripheral blood mononuclear cells (PBMCs) derived from healthy control (HC) individuals, HIV-infected patients with IDU (HIV-IDU) and without IDU (HIV-nIDU). In addition, the Gene Set Enrichment Analysis (GSEA) was used to analyze the immunomodulatory effects of differential immune cells.

RESULTS

Seven types of cells were identified with specific expressions of maker genes. Specific subsets such as CD14+ monocytes, plasmacytoid dendritic cells (pDCs), plasma cells, and CD8+ T cells displayed a high degree of heterogeneity among HC, HIV-nIDU, and HIV-IDU. We identified signature genes for each subset in distinct groups, including CFP+ CD14+ monocytes, PTPRCAP+ pDCs, IGHD+ plasma cells, and IFITM1+ CD8+T cells from HIV-IDU, whereas these genes were not expressed in such cells from HIV-nIDU. Moreover, considerable heterogeneity in the function of these immune cells was observed across different groups, especially the elevated IFN-α/β signaling for CD14+ monocytes, histone H2A/2B and H3/4 pathway for pDCs, the creation of C4 and C2 activators for plasma cells, and drug metabolism cytochrome p450 for CD8+ T cells in HIV-IDU individuals.

CONCLUSION

Our comprehensive analyses clarify the heterogeneous characteristics of the immune landscape between HIV-IDU and HIV-nIDU. These insights provide a deeper understanding of the IDU-mediated immunopathogenesis in HIV infection.

Illicit Drugs in Surface Waters: How to Get Fish off the Addictive Hook

The United Nations World Drug Report published in 2022 alarmed that the global market of illicit drugs is steadily expanding in space and scale. Substances of abuse are usually perceived in the light of threats to human health and public security, while the environmental aspects of their use and subsequent emissions usually remain less explored. However, as with other human activities, drug production, trade, and consumption of drugs may leave their environmental mark. Therefore, this paper aims to review the occurrence of illicit drugs in surface waters and their bioaccumulation and toxicity in fish. Illicit drugs of different groups, i.e., psychostimulants (methamphetamines/amphetamines, cocaine, and its metabolite benzoylecgonine) and depressants (opioids: morphine, heroin, methadone, fentanyl), can reach the aquatic environment through wastewater discharge as they are often not entirely removed during wastewater treatment processes, resulting in their subsequent circulation in nanomolar concentrations, potentially affecting aquatic biota, including fish. Exposure to such xenobiotics can induce oxidative stress and dysfunction to mitochondrial and lysosomal function, distort locomotion activity by regulating the dopaminergic and glutamatergic systems, increase the predation risk, instigate neurological disorders, disbalance neurotransmission, and produce histopathological alterations in the brain and liver tissues, similar to those described in mammals. Hence, this drugs-related multidimensional harm to fish should be thoroughly investigated in line with environmental protection policies before it is too late. At the same time, selected fish species (e.g., Danio rerio, zebrafish) can be employed as models to study toxic and binge-like effects of psychoactive, illicit compounds.

The Common Denominators of Parkinson's Disease Pathogenesis and Methamphetamine Abuse

The pervasiveness and mortality associated with methamphetamine abuse have doubled during the past decade, suggesting a possible worldwide substance use crisis. Epitomizing the pathophysiology and toxicology of methamphetamine abuse proclaims severe signs and symptoms of neurotoxic and neurobehavioral manifestations in both humans and animals. Most importantly, chronic use of this drug enhances the probability of developing neurodegenerative diseases manifolds. Parkinson's disease is one such neurological disorder, which significantly and evidently not only shares a number of toxic pathogenic mechanisms induced by methamphetamine exposure but is also interlinked both structurally and genetically. Methamphetamine-induced neurodegeneration involves altered dopamine homeostasis that promotes the aggregation of α-synuclein protofibrils in the dopaminergic neurons and drives these neurons to make them more vulnerable to degeneration, as recognized in Parkinson's disease. Moreover, the pathologic mechanisms such as mitochondrial dysfunction, oxidative stress, neuroinflammation and decreased neurogenesis detected in methamphetamine abusers dramatically resemble to what is observed in Parkinson's disease cases. Therefore, the present review comprehensively cumulates a holistic illustration of various genetic and molecular mechanisms putting across the notion of how methamphetamine administration and intoxication might lead to Parkinson's disease-like pathology and Parkinsonism.

Methamphetamine (MA) use and MA-induced psychosis are associated with increasing aberrations in the compensatory immunoregulatory system, interleukin-1α, and CCL5 levels

There are only a few studies reporting on the immunological profiles of methamphetamine (MA) use, MA dependency, or MA-induced psychosis (MAP). This study measured M1 macrophage, T helper (Th)-1, Th-2, growth factor, and chemokine profiles, as well as the immune inflammatory response system (IRS) and compensatory immunoregulatory system (CIRS) in peripheral blood samples from patients with MA use (n = 51), MA dependence (n = 47), and MAP (n = 43) in comparison with controls (n = 32). We discovered that persistent MA use had a robust immunosuppressive impact on all immunological profiles. The most reliable biomarker profile of MA use is the combination of substantial CIRS suppression and a rise in selected pro-inflammatory cytokines, namely CCL27 (CTACK), CCL11 (eotaxin), and interleukin (IL)-1α. In addition, MA dependency is associated with increased immunosuppression, as demonstrated by lower stem cell factor levels and higher IL-10 levels. MAP is related to a significant decrease in all immunological profiles, particularly CIRS, and an increase in CCL5 (RANTES), IL-1α, and IL-12p70 signaling. In conclusion, long-term MA use and dependency severely undermine immune homeostasis, whereas MAP may be the consequence of increased IL-1α - CCL5 signaling superimposed on strongly depleted CIRS and Th-1 functions. The widespread immunosuppression established in longstanding MA use may increase the likelihood of infectious and immune illness or exacerbate disorders such as hepatitis and AIDS. Furthermore, elevated levels of CCL5, CCL11, CCL27, IL-1α, and/or IL-12p70 may play a role in the peripheral (atherosclerosis, cutaneous inflammation, immune aberrations, hypospermatogenesis) and central (neuroinflammation, neurotoxic, neurodegenerative, depression, anxiety, and psychosis) side effects of MA use.

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.

Methamphetamine exposure drives cell cycle exit and aberrant differentiation in rat hippocampal-derived neurospheres

Introduction: Methamphetamine (METH) abuse by pregnant drug addicts causes toxic effects on fetal neurodevelopment; however, the mechanism underlying such effect of METH is poorly understood. Methods: In the present study, we applied three-dimensional (3D) neurospheres derived from the embryonic rat hippocampal tissue to investigate the effect of METH on neurodevelopment. Through the combination of whole genome transcriptional analyses, the involved cell signalings were identified and investigated. Results: We found that METH treatment for 24 h significantly and concentration-dependently reduced the size of neurospheres. Analyses of genome-wide transcriptomic profiles found that those down-regulated differentially expressed genes (DEGs) upon METH exposure were remarkably enriched in the cell cycle progression. By measuring the cell cycle and the expression of cell cycle-related checkpoint proteins, we found that METH exposure significantly elevated the percentage of G0/G1 phase and decreased the levels of the proteins involved in the G1/S transition, indicating G0/G1 cell cycle arrest. Furthermore, during the early neurodevelopment stage of neurospheres, METH caused aberrant cell differentiation both in the neurons and astrocytes, and attenuated migration ability of neurospheres accompanied by increased oxidative stress and apoptosis. Conclusion: Our findings reveal that METH induces an aberrant cell cycle arrest and neuronal differentiation, impairing the coordination of migration and differentiation of neurospheres.

Nanowired Delivery of Mesenchymal Stem Cells with Antioxidant Compound H-290/51 Reduces Exacerbation of Methamphetamine Neurotoxicity in Hot Environment

Military personnel are often exposed to hot environments either for combat operations or peacekeeping missions. Hot environment is a severe stressful situation leading to profound hyperthermia, fatigue and neurological impairments. To avoid stressful environment, some people frequently use methamphetamine (METH) or other psychostimulants to feel comfortable under adverse situations. Our studies show that heat stress alone induces breakdown of the blood-brain barrier (BBB) and edema formation associated with reduced cerebral blood flow (CBF). On the other hand, METH alone induces hyperthermia and neurotoxicity. These effects of METH are exacerbated at high ambient temperatures as seen with greater breakdown of the BBB and brain pathology. Thus, a combination of METH use at hot environment may further enhance the brain damage-associated behavioral dysfunctions. METH is well known to induce severe oxidative stress leading to brain pathology. In this investigation, METH intoxication at hot environment was examined on brain pathology and to explore suitable strategies to induce neuroprotection. Accordingly, TiO₂-nanowired delivery of H-290/51 (150 mg/kg, i.p.), a potent chain-breaking antioxidant in combination with mesenchymal stem cells (MSCs), is investigated in attenuating METH-induced brain damage at hot environment in model experiments. Our results show that nanodelivery of H-290/51 with MSCs significantly enhanced CBF and reduced BBB breakdown, edema formation and brain pathology following METH exposure at hot environment. These observations are the first to point out that METH exacerbated brain pathology at hot environment probably due to enhanced oxidative stress, and MSCs attenuate these adverse effects, not reported earlier.

Dynamic immune and exosome transcriptomic responses in patients undergoing psychostimulant methamphetamine withdrawal

Methamphetamine (METH) addiction and withdrawal cause serious harm to both the immune system and nervous system. However, the pathogenesis remains largely unknown. Herein, we investigated the peripheral cytokines and exosomal transcriptome regulatory networks in the patients with METH use disorders (MUDs) undergoing withdrawal. Twenty-seven cytokines were simultaneously assessed in 51 subjects, including 22 at the acute withdrawal (AW) stage and 29 at the protracted withdrawal (PW) stage, and 31 age and gender-matched healthy controls (HCs). Compared to the HCs, significantly decreased levels of interleukin (IL)-1β, IL-9, IL-15, Basic FGF, and MIP1a, increased levels of IL-1rα, IL-6, Eotaxin IP-10, VEGF, and RANTES were identified in AW. These disturbances were mostly or partly restored to the baseline in PW. However, the cytokines IL-6, IL-7, and IL-12p70 were consistently increased even after one year of withdrawal. Besides, a significant decrease in CD3+T and CD4+T cell numbers was observed in AW, and the diminishment was restored to baseline in PW. Comparatively, there were no statistically significant changes in CD8+T, NK, and B cells. Furthermore, the exosomal mRNAs and long non-coding RNAs (lncRNA) were profiled, and the lncRNA-miRNA-mRNA networks were constructed and associated with METH AW and PW stages. Notably, the chemokine signaling was remarkably upregulated during AW. By contrast, the differentially expressed mRNAs/lincRNAs were significantly enriched in neurodegeneration-related diseases. Taken together, a group of METH withdrawal-related cytokines and exosomal mRNA/lncRNA regulatory networks were obtained, which provides a useful experimental and theoretical basis for further understanding of the pathogenesis of the withdrawal symptoms in MUDs.

Effects and associated transcriptomic landscape changes of methamphetamine on immune cells

Background

Methamphetamine (METH) abuse causes serious health problems, including injury to the immune system, leading to increased incidence of infections and even making withdrawal more difficult. Of course, immune cells, an important part of the immune system, are also injured in methamphetamine abuse. However, due to different research models and the lack of bioinformatics, the mechanism of METH injury to immune cells has not been clarified.

Methods

We examined the response of three common immune cell lines, namely Jurkat, NK-92 and THP-1 cell lines, to methamphetamine by cell viability and apoptosis assay in vitro, and examined their response patterns at the mRNA level by RNA-sequencing. Differential expression analysis of two conditions (control and METH treatment) in three types of immune cells was performed using the DESeq2 R package (1.20.0). And some of the differentially expressed genes were verified by qPCR. We performed Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analysis of differentially expressed genes by the clusterProfiler R package (3.14.3). And gene enrichment analysis was also performed using MetaScape (www.metascape.org).

Results

The viability of the three immune cells was differentially affected by methamphetamine, and the rate of NK-cell apoptosis was significantly increased. At the mRNA level, we found disorders of cholesterol metabolism in Jurkat cells, activation of ERK1 and ERK2 cascade in NK-92 cells, and disruption of calcium transport channels in THP-1 cells. In addition, all three cells showed changes in the phospholipid metabolic process.

Conclusions

The results suggest that both innate and adaptive immune cells are affected by METH abuse, and there may be commonalities between different immune cells at the transcriptome level. These results provide new insights into the potential effects by which METH injures the immune cells.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01295-9.

Transcriptomic Profiling Reveals Underlying Immunoregulation Mechanisms of Resistant Hypertension in Injection Drug Users

Background

Hypertension is a common complication in injection drug users (IDU), especially a high proportion of resistant hypertension occurs among them. However, the involving mechanisms remain largely unknown.

Methods

We here investigated the key signaling moieties in resistant hypertension in drug users. Analyses were performed with high-throughput transcriptomic sequencing data of peripheral blood from individuals with drug-sensitive hypertension (Ctrl-DS), IDU with resistant hypertension (IDU-DR), and IDU with sensitive hypertension (IDU-DS).

Results

We showed that 17 and 1 genes in IDU-DS, 48 and 4 genes in IDU-DR were upregulated and downregulated compared Ctrl-DS, and 2 and 4 genes were upregulated and downregulated in IDU-DR compared with IDU-DS, respectively (p ≤ 0.01 and |log₂(FC)| ≥ 1). Differentially expressed genes (DEGs) between Ctrl-DS and IDU-DS were mainly involved in Gene ontology terms of immunoglobulin complex and blood microparticle. DEGs between IDU-DS and IDU-DR were mainly involved in immune system process and immunoglobulin complex. DEGs between Ctrl-DS and IDU-DR were mainly involved in immunoglobulin complex, blood microparticle and cytoplasmic vesicle lumen. We identified 2 gene clusters (brown modules, MEbrown; turquoise module, MEturquoise) correlated with IDU-DR and a gene cluster (magenta module, MEmagenta) correlated with IDU-DS by weighted gene co-expression network analysis (WGCNA). Functional analysis demonstrated that pathways of focal adhesion and focalin-1-rich granule lumen were involved in the development of IDU-DR, and the cytosolic large ribosomal subunit may relate to IDU-DR. Further, immune cell infiltration analysis demonstrated that the abundance of dendritic cells (DCs), natural Treg cells (nTreg), and exhausted T cells (Tex) in IDU-DR and IDU-DS, naïve CD8⁺ T cells in IDU-DS was significantly different compared with that in Ctrl-DS. The abundance of cytotoxic T cells (Tc) was significantly different between IDU-DS and IDU-DR.

Conclusion

Our findings indicated a potential function of immunoregulation mechanisms for resistant hypertension.

Drugs and Bugs: The Gut-Brain Axis and Substance Use Disorders

Substance use disorders (SUDs) represent a significant public health crisis. Worldwide, 5.4% of the global disease burden is attributed to SUDs and alcohol use, and many more use psychoactive substances recreationally. Often associated with comorbidities, SUDs result in changes to both brain function and physiological responses. Mounting evidence calls for a precision approach for the treatment and diagnosis of SUDs, and the gut microbiome is emerging as a contributor to such disorders. Over the last few centuries, modern lifestyles, diets, and medical care have altered the health of the microbes that live in and on our bodies; as we develop, our diets and lifestyle dictate which microbes flourish and which microbes vanish. An increase in antibiotic treatments, with many antibiotic interventions occurring early in life during the microbiome's normal development, transforms developing microbial communities. Links have been made between the microbiome and SUDs, and the microbiome and conditions that are often comorbid with SUDs such as anxiety, depression, pain, and stress. A better understanding of the mechanisms influencing behavioral changes and drug use is critical in developing novel treatments for SUDSs. Targeting the microbiome as a therapeutic and diagnostic tool is a promising avenue of exploration. This review will provide an overview of the role of the gut-brain axis in a wide range of SUDs, discuss host and microbe pathways that mediate changes in the brain's response to drugs, and the microbes and related metabolites that impact behavior and health within the gut-brain axis.

Methamphetamine Dysregulation of the Central Nervous System and Peripheral Immunity

Methamphetamine (METH) is a potent psychostimulant that increases extracellular monoamines, such as dopamine and norepinephrine, and affects multiple tissue and cell types in the central nervous system (CNS) and peripheral immune cells. The reinforcing properties of METH underlie its significant abuse potential and dysregulation of peripheral immunity and central nervous system functions. Together, the constellation of METH's effects on cellular targets and regulatory processes has led to immune suppression and neurodegeneration in METH addicts and animal models of METH exposure. Here we extensively review many of the cell types and mechanisms of METH-induced dysregulation of the central nervous and peripheral immune systems. SIGNIFICANCE STATEMENT: Emerging research has begun to show that methamphetamine regulates dopaminergic neuronal activity. In addition, METH affects non-neuronal brain cells, such as microglia and astrocytes, and immunological cells of the periphery. Concurrent disruption of bidirectional communication between dopaminergic neurons and glia in the CNS and peripheral immune cell dysregulation gives rise to a constellation of dysfunctional neuronal, cell, and tissue types. Therefore, understanding the pathophysiology of METH requires consideration of the multiple targets at the interface between basic and clinical neuroscience.

Methamphetamine facilitates pulmonary and splenic tissue injury and reduces T cell infiltration in C57BL/6 mice after antigenic challenge

Methamphetamine (METH) is a strong addictive central nervous system stimulant. METH abuse can alter biological processes and immune functions necessary for host defense. The acquisition and transmission of HIV, hepatitis, and other communicable diseases are possible serious infectious consequences of METH use. METH also accumulates extensively in major organs. Despite METH being a major public health and safety problem globally, there are limited studies addressing the impact of this popular recreational psychostimulant on tissue adaptive immune responses after exposure to T cell dependent [ovalbumin (OVA)] and independent [lipopolysaccharide (LPS)] antigens. We hypothesized that METH administration causes pulmonary and splenic tissue alterations and reduces T cell responses to OVA and LPS in vivo, suggesting the increased susceptibility of users to infection. Using a murine model of METH administration, we showed that METH causes tissue injury, apoptosis, and alters helper and cytotoxic T cell recruitment in antigen challenged mice. METH also reduces the expression and distribution of CD3 and CD28 molecules on the surface of human Jurkat T cells. In addition, METH decreases the production of IL-2 in these T-like cells, suggesting a negative impact on T lymphocyte activation and proliferation. Our findings demonstrate the pleotropic effects of METH on cell-mediated immunity. These alterations have notable implications on tissue homeostasis and the capacity of the host to respond to infection.

6,7,4[Formula: see text]-Trihydroxyflavanone Prevents Methamphetamine-Induced T Cell Deactivation by Protecting the Activated T Cells from Apoptosis

Methamphetamine (METH) is an extremely addictive drug that has raised serious public health concerns recently. METH addiction not only results in neuronal cytotoxicity, but it also affects immune cell activity, including T lymphocytes. 6,4,7[Formula: see text]-trihydroxyflavanone (THF), isolated from Dalbergia odorifera, has been studied for its antibacterial activity, but evidence for whether THF has an anti-cytotoxic and protective effect on T cell activation exposed to METH is lacking. In this study, results showed that treatment with THF was not cytotoxic to Jurkat T cells but dose-dependently mitigated the cytotoxicity induced by exposure to METH. The Western blot results demonstrating pre-treatment with THF maintained the expression of anti-apoptotic proteins and phosphorylation of PI3K/Akt/mTOR downregulated by treatment with METH. Furthermore, we found that decreased expression of IL-2 and CD69 by METH exposure was partially restored, and viability was significantly prevented by pre-treatment with THF in activated T cells. These findings were involved in re-elevated expression of anti-apoptotic proteins as well as recovered pathways including MAPK/PI3K/Akt/mTOR in activated T cells pre-exposed to METH. Our results suggest beneficial effects of THF against the cytotoxic and immune-modulating effect of METH on T cells and therapeutic potential of THF for patients with immunodeficiency caused by METH addiction.

Intoxication With Endogenous Angiotensin II: A COVID-19 Hypothesis

Severe acute respiratory syndrome coronavirus 2 has spread rapidly around the globe. However, despite its high pathogenicity and transmissibility, the severity of the associated disease, COVID-19, varies widely. While the prognosis is favorable in most patients, critical illness, manifested by respiratory distress, thromboembolism, shock, and multi-organ failure, has been reported in about 5% of cases. Several studies have associated poor COVID-19 outcomes with the exhaustion of natural killer cells and cytotoxic T cells, lymphopenia, and elevated serum levels of D-dimer. In this article, we propose a common pathophysiological denominator for these negative prognostic markers, endogenous, angiotensin II toxicity. We hypothesize that, like in avian influenza, the outlook of COVID-19 is negatively correlated with the intracellular accumulation of angiotensin II promoted by the viral blockade of its degrading enzyme receptors. In this model, upregulated angiotensin II causes premature vascular senescence, leading to dysfunctional coagulation, and immunity. We further hypothesize that angiotensin II blockers and immune checkpoint inhibitors may be salutary for COVID-19 patients with critical illness by reversing both the clotting and immune defects (Graphical Abstract).

The impact of substance abuse on HIV-mediated neuropathogenesis in the current ART era

Approximately 37 million people worldwide are infected with human immunodeficiency virus (HIV). One highly significant complication of HIV infection is the development of HIV-associated neurocognitive disorders (HAND) in 15-55% of people living with HIV (PLWH), that persists even in the antiretroviral therapy (ART) era. The entry of HIV into the central nervous system (CNS) occurs within 4-8 days after peripheral infection. This establishes viral reservoirs that may persist even in the presence of ART. Once in the CNS, HIV infects resident macrophages, microglia, and at low levels, astrocytes. In response to chronic infection and cell activation within the CNS, viral proteins, inflammatory mediators, and host and viral neurotoxic factors produced over extended periods of time result in neuronal injury and loss, cognitive deficits and HAND. Substance abuse is a common comorbidity in PLWH and has been shown to increase neuroinflammation and cognitive disorders. Additionally, it has been associated with poor ART adherence, and increased viral load in the cerebrospinal fluid (CSF), that may also contribute to increased neuroinflammation and neuronal injury. Studies have examined mechanisms that contribute to neuroinflammation and neuronal damage in PLWH, and how substances of abuse exacerbate these effects. This review will focus on how substances of abuse, with an emphasis on methamphetamine (meth), cocaine, and opioids, impact blood brain barrier (BBB) integrity and transmigration of HIV-infected and uninfected monocytes across the BBB, as well as their effects on monocytes/macrophages, microglia, and astrocytes within the CNS. We will also address how these substances of abuse may contribute to HIV-mediated neuropathogenesis in the context of suppressive ART. Additionally, we will review the effects of extracellular dopamine, a neurotransmitter that is increased in the CNS by substances of abuse, on HIV neuropathogenesis and how this may contribute to neuroinflammation, neuronal insult, and HAND in PLWH with active substance use. Lastly, we will discuss some potential therapies to limit CNS inflammation and damage in HIV-infected substance abusers.

Alterations to the Gastrointestinal Microbiome Associated with Methamphetamine Use among Young Men who have Sex with Men

Methamphetamine (MA) use is a major public health problem in the United States, especially among people living with HIV (PLWH). Many MA-induced neurotoxic effects are mediated by inflammation and gut microbiota may play a role in this process, yet the effects of MA on the microbiome have not been adequately explored. Therefore, we performed 16S rRNA gene sequencing on rectal swab samples from 381 men who have sex with men, 48% of whom were PLWH and 41% of whom used MA. We compared microbiome composition between MA users and non-users while testing for potential interactions with HIV and controlling for numerous confounders using inverse probability of treatment weighting. We found that MA use explained significant variation in overall composition (R² = 0.005, p = 0.008) and was associated with elevated Finegoldia, Parvimonas, Peptoniphilus, and Porphyromonas and reduced Butyricicoccus and Faecalibacterium, among others. Genera including Actinomyces and Streptobacillus interacted with HIV status, such that they were increased in HIV+ MA users. Finegoldia and Peptoniphilus increased with increasing frequency of MA use, among others. In summary, MA use was associated with a microbial imbalance favoring pro-inflammatory bacteria, including some with neuroactive potential and others that have previously been associated with poor HIV outcomes.

Methamphetamine functions as a novel CD4+ T-cell activator via the sigma-1 receptor to enhance HIV-1 infection

Methamphetamine (Meth) exacerbates HIV-1 pathobiology by increasing virus transmission and replication and accelerating clinical progression to AIDS. Meth has been shown to alter the expression of HIV-1 co-receptors and impair intrinsic resistance mechanisms of immune cells. However, the exact molecular mechanisms involved in augmenting HIV-1 replication in T-cells are still not yet clear. Here, we demonstrate that pretreatment with Meth of CD4+ T-cells enhanced HIV-1 replication. We observed upregulation of CD4+ T-cell activation markers and enhanced expression of miR-34c-5p and miR-155 in these cells. Further, we noted activation of the sigma-1 receptor and enhanced intracellular Ca2+ concentration and cAMP release in CD4+ T-cells upon Meth treatment, which resulted in increased phosphorylation and nuclear translocation of transcription factors NFκB, CREB, and NFAT1. Increased gene expression of IL-4 and IL-10 was also observed in Meth treated CD4+ T-cells. Moreover, proteasomal degradation of Ago1 occurred upon Meth treatment, further substantiating the drug as an activator of T-cells. Taken together, these findings show a previously unreported mechanism whereby Meth functions as a novel T-cell activator via the sigma-1 signaling pathway, enhancing replication of HIV-1 with expression of miR-34c-5p, and transcriptional activation of NFκB, CREB and NFAT1.

Methamphetamine and its immune-modulating effects

The recreational use of methamphetamine (METH, or ice) is a global burden. It pervades and plagues contemporary society; it has been estimated that there are up to 35 million users worldwide. METH is a highly addictive psychotropic compound which acts on the central nervous system, and chronic use can induce psychotic behavior. METH has the capacity to modulate immune cells, giving the drug long-term effects which may manifest as neuropsychiatric disorders, and that increase susceptibility to communicable diseases, such as HIV. In addition, changes to the cytokine balance have been associated with compromise of the blood-brain barrier, resulting to alterations to brain plasticity, creating lasting neurotoxicity. Immune-related signaling pathways are key to further evaluating how METH impacts host immunity through these neurological and peripheral modifications. Combining this knowledge with current data on inflammatory responses will improve understanding of how the adaptive and innate immunity responds to METH, how this can activate premature-ageing processes and how METH exacerbates disturbances that lead to non-communicable age-related diseases, including cardiovascular disease, stroke, depression and dementia.