Macrophages and brown adipocytes cross-communicate to modulate a thermogenic program following methamphetamine exposure.

Hyperthermia is a potentially lethal side-effect of Methamphetamine (Meth), a stimulant drug. Activation of non-shivering thermogenesis in brown adipose tissue (BAT) is partly responsible for Meth-induced rise in temperature, with contributing sympathetic neurotransmitters, such as norepinephrine (NE), and reactive oxygen species (ROS). However, the mechanisms controlling the development of a molecular thermogenic program in brown adipocytes (BA) following Meth are unknown. We hypothesize that Meth and NE affect BAT cells, BA and macrophages, to modify their physiology and interactions, with consequences to thermogenic genes. We also hypothesize that ROS play a critical role in signaling transcription of thermogenic genes and their regulatory components. Using primary BA and macrophage cultures, we measured Meth and NE interference with physiological and phenotypic measures that are relevant to thermogenesis in BAT. Meth caused both BA and macrophages to decrease mitochondrial maximal capacity and increase ROS. In BA, the thermogenic genes UCP1, PPARγ, PGC1α and GADD45γ were transcriptionally increased by Meth in a ROS-dependent manner. In macrophages, Meth increased oxidative stress response and caused a predominance of M2 subset markers. BA transcriptional changes in response to Meth and NE were significantly controlled by macrophages. The results suggest that BA and macrophages respond to Meth and NE, with effects on mitochondrial functions and transcription of genes involved in thermogenesis. ROS-dependent signals in BA and cellular interactions between BA and macrophages synergize to regulate the BAT environment and control critical pathways leading to Meth-hyperthermia.

Methamphetamine abuse affects gene expression in brain-derived microglia of SIV-infected macaques to enhance inflammation and promote virus targets.

BACKGROUND: Methamphetamine (Meth) abuse is a major health problem linked to the aggravation of HIV- associated complications, especially within the Central Nervous System (CNS). Within the CNS, Meth has the ability to modify the activity/function of innate immune cells and increase brain viral loads. Here, we examined changes in the gene expression profile of neuron-free microglial cell preparations isolated from the brain of macaques infected with the Simian Immunodeficiency Virus (SIV), a model of neuroAIDS, and exposed to Meth. We aimed to identify molecular patterns triggered by Meth that could explain the detection of higher brain viral loads and the development of a pro-inflammatory CNS environment in the brain of infected drug abusers. RESULTS: We found that Meth alone has a strong effect on the transcription of genes associated with immune pathways, particularly inflammation and chemotaxis. Systems analysis led to a strong correlation between Meth exposure and enhancement of molecules associated with chemokines and chemokine receptors, especially CXCR4 and CCR5, which function as co-receptors for viral entry. The increase in CCR5 expression was confirmed in the brain in correlation with increased brain viral load. CONCLUSIONS: Meth enhances the availability of CCR5-expressing cells for SIV in the brain, in correlation with increased viral load. This suggests that Meth is an important factor in the susceptibility to the infection and to the aggravated CNS inflammatory pathology associated with SIV in macaques and HIV in humans.

Cutting edge: IL-13Rα1 expression in dopaminergic neurons contributes to their oxidative stress-mediated loss following chronic peripheral treatment with lipopolysaccharide.

Inflammation and its mediators, including cytokines and reactive oxygen species, are thought to contribute to neurodegeneration. In the mouse brain, we found that IL-13Rα1 was expressed in the dopaminergic (DA) neurons of the substantia nigra pars compacta, which are preferentially lost in human Parkinson's disease. Mice deficient for Il13ra1 exhibited resistance to loss of DA neurons in a model of chronic peripheral inflammation using bacterial LPS. IL-13, as well as IL-4, potentiated the cytotoxic effects of t-butyl hydroperoxide and hydrogen peroxide on mouse DA MN9D cells. Collectively, our data indicate that expression of IL-13Rα1 on DA neurons can increase their susceptibility to oxidative stress-mediated damage, thereby contributing to their preferential loss. In humans, Il13ra1 lies on the X chromosome within the PARK12 locus of susceptibility to Parkinson's disease, suggesting that IL-13Rα1 may have a role in the pathogenesis of this neurodegenerative disease.

Osteopontin expression in the brain triggers localized inflammation and cell death when immune cells are activated by pertussis toxin.

Upregulation of osteopontin (OPN) is a characteristic of central nervous system pathologies. However, the role of OPN in inflammation is still controversial, since it can both prevent cell death and induce the migration of potentially damaging inflammatory cells. To understand the role of OPN in inflammation and cell survival, we expressed OPN, utilizing an adenoviral vector, in the caudoputamen of mice deficient in OPN, using beta-galactosidase- (ß-gal-) expressing vector as control. The tissue pathology and the expression of proinflammatory genes were compared in both treatments. Interestingly, inflammatory infiltrate was only found when the OPN-vector was combined with a peripheral treatment with pertussis toxin (Ptx), which activated peripheral cells to express the OPN receptor CD44v6. Relative to ß-gal, OPN increased the levels of inflammatory markers, including IL13Rα1, CXCR3, and CD40L. In Ptx-treated OPN KOs, apoptotic TUNEL+ cells surrounding the OPN expression site increased, compared to ß-gal. Together, these results show that local OPN expression combined with a peripheral inflammatory stimulus, such as Ptx, may be implicated in the development of brain inflammation and induction of cell death, by driving a molecular pattern characteristic of cytotoxicity. These are characteristics of inflammatory pathologies of the CNS in which OPN upregulation is a hallmark.

MRP8/14 Is a Molecular Signature Triggered by Dopamine in HIV Latent Myeloid Targets That Increases HIV Transcription and Distinguishes HIV+ Methamphetamine Users with Detectable CSF Viral Load and Brain Pathology.

There is a significant overlap between HIV infection and substance-use disorders. Dopamine (DA) is the most abundantly upregulated neurotransmitter in methamphetamine abuse, with receptors (DRD1-5) that are expressed by neurons as well as by a large diversity of cell types, including innate immune cells that are the targets of HIV infection, making them responsive to the hyperdopaminergic environment that is characteristic of stimulant drugs. Therefore, the presence of high levels of dopamine may affect the pathogenesis of HIV, particularly in the brain. The stimulation of HIV latently infected U1 promonocytes with DA significantly increased viral p24 levels in the supernatant at 24 h, suggesting effects on activation and replication. Using selective agonists to different DRDs, we found that DRD1 played a major role in activating viral transcription, followed by DRD4, which increased p24 with a slower kinetic rate compared to DRD1. Transcriptome and systems biology analyses led to the identification of a cluster of genes responsive to DA, where S100A8 and S100A9 were most significantly correlated with the early increase in p24 levels following DA stimulation. Conversely, DA increased the expression of these genes' transcripts at the protein level, MRP8 and MRP14, respectively, which form a complex also known as calprotectin. Interestingly, MRP8/14 was able to stimulate HIV transcription in latent U1 cells, and this occurred via binding of the complex to the receptor for an advanced glycosylation end-product (RAGE). Using selective agonists, both DRD1 and DRD4 increased MRP8/14 on the surface, in the cytoplasm, as well as secreted in the supernatants. On the other hand, while DRD1/5 did not affect the expression of RAGE, DRD4 stimulation caused its downregulation, offering a mechanism for the delayed effect via DRD4 on the p24 increase. To cross-validate MRP8/14 as a DA signature with a biomarker value, we tested its expression in HIV+ Meth users' postmortem brain specimens and peripheral cells. MRP8/14+ cells were more frequently identified in mesolimbic areas such as the basal ganglia of HIV+ Meth+ cases compared to HIV+ non-Meth users or to controls. Likewise, MRP8/14+ CD11b+ monocytes were more frequent in HIV+ Meth users, particularly in specimens from participants with a detectable viral load in the CSF. Overall, our results suggest that the MRP8 and MRP14 complex may serve as a signature to distinguish subjects using addictive substances in the context of HIV, and that this may play a role in aggravating HIV pathology by promoting viral replication in people with HIV who use Meth.

Age-associated changes in microglia activation and Sirtuin-1- chromatin binding patterns.

The aging process is associated with changes in mechanisms maintaining physiology, influenced by genetics and lifestyle, and impacting late life quality and longevity. Brain health is critical in healthy aging. Sirtuin 1 (Sirt1), a histone deacetylase with silencing properties, is one of the molecular determinants experimentally linked to health and longevity. We compared brain pathogenesis and Sirt1-chromatin binding dynamics in brain pre-frontal cortex from 2 groups of elder rhesus macaques, divided by age of necropsy: shorter-lived animals (18-20 years old (yo)), equivalent to 60-70 human yo; and longer-lived animals (23-29 yo), corresponding to 80-100 human yo and modeling successful aging. These were compared with young adult brains (4-7 yo). Our findings indicated drastic differences in the microglia marker Iba1, along with factors influencing Sirt1 levels and activity, such as CD38 (an enzyme limiting NAD that controls Sirt1 activity) and mir142 (a microRNA targeting Sirt1 transcription) between the elder groups. Iba1 was lower in shorter-lived animals than in the other groups, while CD38 was higher in both aging groups compared to young. mir142 and Sirt1 levels were inversely correlated in longer-lived brains (>23yo), but not in shorter-lived brains (18-20 yo). We also found that Sirt1 binding showed signs of better efficiency in longer-lived animals compared to shorter-lived ones, in genes associated with nuclear activity and senescence. Overall, differences in neuroinflammation and Sirt1 interactions with chromatin distinguished shorter- and longer-lived animals, suggesting the importance of preserving microglia and Sirt1 functional efficiency for longevity.

Methamphetamine signals transcription of IL1ß and TNFα in a reactive oxygen species-dependent manner and interacts with HIV-1 Tat to decrease antioxidant defense mechanisms.

Methamphetamine (Meth) abuse is a common HIV co-morbidity that is linked to aggravated Central Nervous System (CNS) inflammation, which accentuates HIV- associated neurological disorders, triggered both directly or indirectly by the drug. We used the well-established human innate immune macrophage cell line system (THP1) to demonstrate that Reactive Oxygen Species (ROS) immediately induced by Meth play a role in the increased transcription of inflammatory genes, in interaction with HIV-1 Tat peptide. Meth and Tat, alone and together, affect early events of transcriptional activity, as indicated by changes in RNA polymerase (RNAPol) recruitment patterns throughout the genome, via ROS-dependent and -independent mechanisms. IL1ß (IL1ß) and TNF α (TNFα), two genes with defining roles in the inflammatory response, were both activated in a ROS-dependent manner. We found that this effect occurred via the activation of the activator protein 1 (AP-1) comprising cFOS and cJUN transcription factors and regulated by the SRC kinase. HIV-1 Tat, which was also able to induce the production of ROS, did not further impact the effects of ROS in the context of Meth, but promoted gene activity independently from ROS, via additional transcription factors. For instance, HIV-1 Tat increased NFkB activation and activated gene clusters regulated by Tata box binding peptide, ING4 and IRF2. Importantly, HIV-1 Tat decreased the expression of anti-oxidant genes, where its suppression of the detoxifying machinery may contribute to the aggravation of oxidative stress induced by ROS in the context of Meth. Our results provide evidence of effects of Meth via ROS and interactions with HIV Tat that promote the transcription of inflammatory genes such as IL1ß and TNFα.

Polygenic networks in peripheral leukocytes indicate patterns associated with HIV infection and context-dependent effects of cannabis use.

In spite of suppressive antiretroviral therapies (ART), Human Immunodeficiency Virus (HIV)-infected subjects still experience the consequences of viral persistence and chronic inflammation. In the brain, where most HIV-1 targets are of innate immune origin, neurological and cognitive impairments are detectable and enhanced by highly prevalent substance use disorders. Cannabis is one of the most prevalent substances among HIV+ â€‹subjects, compared to non-infected populations, either prescribed for improving various symptoms or used recreationally, as well as a component of polysubstance use. The mechanisms by which addictive substances and HIV interact are multifactorial and poorly understood. Importantly, the HIV brain target cells, macrophages and microglia, express receptors to neurotransmitters elevated by such drugs, and express receptors to cannabinoids, particularly CB2R. We have tested a panel of 784 transcripts associated with neurological disorders, digitally multiplexed and detectable in peripheral blood cells from a small cohort (n â€‹= â€‹102) of HIV-positive (HIV+) and HIV-negative (HIV-) specimens, stratified based on criteria of lifetime (LT) dependence of cannabis (CAN+) or not (CAN-). Demographic homogeneity and low incidence of co-morbidities helped increase power and allowed the identification of key differences consistent with HIV infection, cannabis exposure, or their interactions. A small percentage of these subjects used cannabis as well as other drugs. The data was analyzed using robust systems and visualization strategies to detect orchestrated patterns in gene networks connected based on molecular interfaces with higher power than in single genes. We found that the effects of cannabis differed drastically between HIV- and HIV+ â€‹groups, particularly in gene networks playing a role in inflammation, neurodegeneration, apoptosis and leukocyte adhesion and transmigration. At the level of individual genes, we identified detrimental effects that were associated with polysubstance use as a covariate, particularly methamphetamine. Transcription factor usage predictions suggest that the effects of cannabis are associated with transcriptional co-regulation at the gene promoters by multiple factors that vary by context. Overall, we have found that the effects of cannabis may be context-dependent, with potential benefits in the context of HIV reflected by improvements in cognition, but in the absence of the polysubstance use component.

Metabolic depression and increased reactive oxygen species production by isolated mitochondria at moderately lower temperatures.

Temperature (T) reduction increases lifespan, but the mechanisms are not understood. Because reactive oxygen species (ROS) contribute to aging, we hypothesized that lowering T might decrease mitochondrial ROS production. We measured respiratory response and ROS production in isolated mitochondria at 32, 35, and 37 °C. Lowering T decreased the rates of resting (state 4) and phosphorylating (state 3) respiration phases. Surprisingly, this respiratory slowdown was associated with an increase of ROS production and hydrogen peroxide release and with elevation of the mitochondrial membrane potential, ΔΨ(m). We also found that at lower T mitochondria produced more carbon-centered lipid radicals, a species known to activate uncoupling proteins. These data indicate that reduced mitochondrial ROS production is not one of the mechanisms mediating lifespan extension at lower T. They suggest instead that increased ROS leakage may mediate mitochondrial responses to hypothermia.

Methamphetamine increases brain viral load and activates natural killer cells in simian immunodeficiency virus-infected monkeys.

Methamphetamine (Meth) abuse increases risky behaviors that contribute to the spread of HIV infection. In addition, because HIV and Meth independently affect physiological systems including the central nervous system, HIV-induced disease may be more severe in drug users. We investigated changes in blood and brain viral load as well as differences in immune cells in chronically simian immunodeficiency virus-infected rhesus macaques that were either administered Meth or used as controls. Although Meth administration did not alter levels of virus in the plasma, viral load in the brain was significantly increased in Meth-treated animals compared with control animals. Meth treatment also resulted in an activation of natural killer cells. Given the prevalence of Meth use in HIV-infected and HIV at-risk populations, these findings reveal the likely untoward effects of Meth abuse in such individuals.

Effects of chronic mental stress and atherogenic diet on the immune inflammatory environment in mouse aorta.

Inflammation and stress are regarded as two important atherogenic factors. Because stress can affect leukocyte distribution, we hypothesized that stress-mediated leukocyte extravasation can modify the inflammatory environment of the arterial wall possibly contributing to atherogenesis. To test this hypothesis we evaluated the inflammatory environment of the aorta in C57Bl/6 mice subjected to 3 and 12 months of chronic stress and compared it to age matched non-stressed animals. Experiments were carried out in mice fed regular chow or atherogenic diets. Both treatments increased the expression of vascular and leukocyte adhesion molecules and leukocyte accumulation. At 3 months, stress but not an atherogenic diet elevated the number of CD4 cells, CD8 cells, macrophages, dendritic cells and neutrophils. These changes were associated with elevation of transcripts for ICAM-1 and VCAM-1, E-selectin and neuropeptide Y. At 12 months, stress or high cholesterol acted similarly to elevate the number of CD8 and macrophages, and synergistically on the number of all cell types investigated. At this time-point, strong synergism was also observed on the level of E-selectin and NPY in the aorta, but not in the circulation. Despite these effects, histological and morphological alterations of the arterial wall were severe in the atherogenic diet, but not in the stress groups. Thus, although stress and an atherogenic diet may both affect leukocyte accumulation in the aorta, they may contribute differently to atherogenesis.

Constitutive and LPS-regulated expression of interleukin-18 receptor beta variants in the mouse brain.

Interleukin (IL)-18 is a pro-inflammatory cytokine that is proposed to be involved in physiological as well as pathological conditions in the adult brain. IL-18 acts through a heterodimer receptor comprised of a subunit alpha (IL-18Rα) required for binding, and a subunit beta (IL-18Rß) necessary for activation of signal transduction. We recently demonstrated that the canonical alpha binding chain, and its putative decoy isoform, are expressed in the mouse central nervous system (CNS) suggesting that IL-18 may act on the brain by directly binding its receptor. Considering that the co-expression of the beta chain seems to be required to generate a functional receptor and, a short variant of this chain has been described in rat and human brain, in this study we have extended our investigation to IL-18Rß in mouse. Using a multi-methodological approach we found that: (1) a short splice variant of IL-18Rß was expressed in the CNS even if at lower levels compared to the full-length IL-18Rß variants, (2) the canonical IL-18Rß is expressed in the CNS particularly in areas and nuclei belonging to the limbic system as previously observed for IL-18Rα and finally (3) we have also demonstrated that both IL-18Rß isoforms are up-regulated in different brain areas three hours after a single lipopolysaccharide (LPS) injection suggesting that IL-18Rß in the CNS might be involved in mediating the endocrine and behavioral effects of LPS. Our data highlight the considerable complexity of the IL-18 regulation activity in the mouse brain and further support an important central role for IL-18.

Detection of H3K4me3 Identifies NeuroHIV Signatures, Genomic Effects of Methamphetamine and Addiction Pathways in Postmortem HIV+ Brain Specimens that Are Not Amenable to Transcriptome Analysis.

Human postmortem specimens are extremely valuable resources for investigating translational hypotheses. Tissue repositories collect clinically assessed specimens from people with and without HIV, including age, viral load, treatments, substance use patterns and cognitive functions. One challenge is the limited number of specimens suitable for transcriptional studies, mainly due to poor RNA quality resulting from long postmortem intervals. We hypothesized that epigenomic signatures would be more stable than RNA for assessing global changes associated with outcomes of interest. We found that H3K27Ac or RNA Polymerase (Pol) were not consistently detected by Chromatin Immunoprecipitation (ChIP), while the enhancer H3K4me3 histone modification was abundant and stable up to the 72 h postmortem. We tested our ability to use HeK4me3 in human prefrontal cortex from HIV+ individuals meeting criteria for methamphetamine use disorder or not (Meth +/-) which exhibited poor RNA quality and were not suitable for transcriptional profiling. Systems strategies that are typically used in transcriptional metadata were applied to H3K4me3 peaks revealing consistent genomic activity differences in regions where addiction and neuronal synapses pathway genes are represented, including genes of the dopaminergic system, as well as inflammatory pathways. The resulting comparisons mirrored previously observed effects of Meth on suppressing gene expression and provided insights on neurological processes affected by Meth. The results suggested that H3K4me3 detection in chromatin may reflect transcriptional patterns, thus providing opportunities for analysis of larger numbers of specimens from cases with substance use and neurological deficits. In conclusion, the detection of H3K4me3 in isolated chromatin can be an alternative to transcriptome strategies to increase the power of association using specimens with long postmortem intervals and low RNA quality.

The COVID-19 Pandemic: Reflections of Science, Person, and Challenge in Academic Research Settings.

In spring of 2021, the Society on NeuroImmune Pharmacology (SNIP) organized a virtual workshop on the coronavirus disease 2019 (COVID-19). The daylong event's fourth and final symposium, "Well-being and reflections," offered a glimpse at the pandemic's impact on the lives of our scientists and educators. This manuscript includes a brief summary of the symposium, a transcription of our incoming president Dr. Santosh Kumar's lecture, titled "Intervention and improved well-being of basic science researchers during the COVID-19 era: a case study," and the panel discussion that followed, "Reflection and sharing," featuring Drs. Jean M. Bidlack, Sylvia Fitting, Santhi Gorantla, Maria Cecilia G. Marcondes, Loyda M. Melendez, and Ilker K. Sariyer. The conclusion of this manuscript includes comments from SNIP's president Dr. Sulie L. Chang and our Chief Editor, Dr. Howard E. Gendelman. Drs. Sowmya Yelamanchili and Jeymohan Joseph co-chaired the symposium.

An integrated systems analysis implicates EGR1 downregulation in simian immunodeficiency virus encephalitis-induced neural dysfunction.

Human immunodeficiency virus (HIV)-associated dementia (HAD) is a syndrome occurring in HIV-infected patients with advanced disease that likely develops as a result of macrophage and microglial activation as well as other immune events triggered by virus in the central nervous system. The most relevant experimental model of HAD, rhesus macaques exhibiting simian immunodeficiency virus (SIV) encephalitis (SIVE), closely reproduces the human disease and has been successfully used to advance our understanding of mechanisms underlying HAD. In this study we integrate gene expression data from uninfected and SIV-infected hippocampus with a human protein interaction network and discover modules of genes whose expression patterns distinguish these two states, to facilitate identification of neuronal genes that may contribute to SIVE/HIV cognitive deficits. Using this approach we identify several downregulated candidate genes and select one, EGR1, a key molecule in hippocampus-related learning and memory, for further study. We show that EGR1 is downregulated in SIV-infected hippocampus and that it can be downregulated in differentiated human neuroblastoma cells by treatment with CCL8, a product of activated microglia. Integration of expression data with protein interaction data to discover discriminatory modules of interacting proteins can be usefully used to prioritize differentially expressed genes for further study. Investigation of EGR1, selected in this manner, indicates that its downregulation in SIVE may occur as a consequence of the host response to infection, leading to deficits in cognition.

The most common Chinese rhesus macaque MHC class I molecule shares peptide binding repertoire with the HLA-B7 supertype.

Of the two rhesus macaque subspecies used for AIDS studies, the Simian immunodeficiency virus-infected Indian rhesus macaque (Macaca mulatta) is the most established model of HIV infection, providing both insight into pathogenesis and a system for testing novel vaccines. Despite the Chinese rhesus macaque potentially being a more relevant model for AIDS outcomes than the Indian rhesus macaque, the Chinese-origin rhesus macaques have not been well-characterized for their major histocompatibility complex (MHC) composition and function, reducing their greater utilization. In this study, we characterized a total of 50 unique Chinese rhesus macaques from several varying origins for their entire MHC class I allele composition and identified a total of 58 unique complete MHC class I sequences. Only nine of the sequences had been associated with Indian rhesus macaques, and 28/58 (48.3%) of the sequences identified were novel. From all MHC alleles detected, we prioritized Mamu-A1*02201 for functional characterization based on its higher frequency of expression. Upon the development of MHC/peptide binding assays and definition of its associated motif, we revealed that this allele shares peptide binding characteristics with the HLA-B7 supertype, the most frequent supertype in human populations. These studies provide the first functional characterization of an MHC class I molecule in the context of Chinese rhesus macaques and the first instance of HLA-B7 analogy for rhesus macaques.

Systems Biology Analysis of the Antagonizing Effects of HIV-1 Tat Expression in the Brain over Transcriptional Changes Caused by Methamphetamine Sensitization.

Methamphetamine (Meth) abuse is common among humans with immunodeficiency virus (HIV). The HIV-1 regulatory protein, trans-activator of transcription (Tat), has been described to induce changes in brain gene transcription that can result in impaired reward circuitry, as well as in inflammatory processes. In transgenic mice with doxycycline-induced Tat protein expression in the brain, i.e., a mouse model of neuroHIV, we tested global gene expression patterns induced by Meth sensitization. Meth-induced locomotor sensitization included repeated daily Meth or saline injections for seven days and Meth challenge after a seven-day abstinence period. Brain samples were collected 30 min after the Meth challenge. We investigated global gene expression changes in the caudate putamen, an area with relevance in behavior and HIV pathogenesis, and performed pathway and transcriptional factor usage predictions using systems biology strategies. We found that Tat expression alone had a very limited impact in gene transcription after the Meth challenge. In contrast, Meth-induced sensitization in the absence of Tat induced a global suppression of gene transcription. Interestingly, the interaction between Tat and Meth broadly prevented the Meth-induced global transcriptional suppression, by maintaining regulation pathways, and resulting in gene expression profiles that were more similar to the controls. Pathways associated with mitochondrial health, initiation of transcription and translation, as well as with epigenetic control, were heavily affected by Meth, and by its interaction with Tat in anti-directional ways. A series of systems strategies have predicted several components impacted by these interactions, including mitochondrial pathways, mTOR/RICTOR, AP-1 transcription factor, and eukaryotic initiation factors involved in transcription and translation. In spite of the antagonizing effects of Tat, a few genes identified in relevant gene networks remained downregulated, such as sirtuin 1, and the amyloid precursor protein (APP). In conclusion, Tat expression in the brain had a low acute transcriptional impact but strongly interacted with Meth sensitization, to modify effects in the global transcriptome.

Sex differences and Tat expression affect dopaminergic receptor expression and response to antioxidant treatment in methamphetamine-sensitized HIV Tat transgenic mice.

Methamphetamine (Meth) abuse is a common HIV comorbidity. Males and females differ in their patterns of Meth use, associated behaviors, and responses, but the underlying mechanisms and impact of HIV infection are unclear. Transgenic mice with inducible HIV-1 Tat protein in the brain (iTat) replicate many neurological aspects of HIV infection in humans. We previously showed that Tat induction enhances the Meth sensitization response associated with perturbation of the dopaminergic system, in male iTat mice. Here, we used the iTat mouse model to investigate sex differences in individual and interactive effects of Tat and Meth challenge on locomotor sensitization, brain expression of dopamine receptors (DRDs) and regulatory adenosine receptors (ADORAs). Because Meth administration increases the production of reactive oxygen species (ROS), we also determined whether the effects of Meth could be rescued by concomitant treatment with the ROS scavenger N-acetyl cysteine (NAC). After Meth sensitization and a 7-day abstinence period, groups of Tat+ and Tat-male and female mice were challenged with Meth in combination with NAC. We confirmed that Tat expression and Meth challenge suppressed DRD mRNA and protein in males and females' brains, and showed that females were particularly susceptible to the effects of Meth on D1-like and D2-like DRD subtypes and ADORAs. The expression of these markers differed strikingly between males and females, and between females in different phases of the estrous cycle, in a Tat -dependent manner. NAC attenuated Meth-induced locomotor sensitization and preserved DRD expression in all groups except for Tat + females. These data identify complex interactions between sex, Meth use, and HIV infection on addiction responses, with potential implications for the treatment of male and female Meth users in the context of HIV, especially those with cognitive disorders.

Methamphetamine and Cannabis: A Tale of Two Drugs and their Effects on HIV, Brain, and Behavior.

HIV infection and drug use intersect epidemiologically, and their combination can result in complex effects on brain and behavior. The extent to which drugs affect the health of persons with HIV (PWH) depends on many factors including drug characteristics, use patterns, stage of HIV disease and its treatment, comorbid factors, and age. To consider the range of drug effects, we have selected two that are in common use by PWH: methamphetamine and cannabis. We compare the effects of methamphetamine with those of cannabis, to illustrate how substances may potentiate, worsen, or even buffer the effects of HIV on the CNS. Data from human, animal, and ex vivo studies provide insights into how these drugs have differing effects on the persistent inflammatory state that characterizes HIV infection, including effects on viral replication, immune activation, mitochondrial function, gut permeability, blood brain barrier integrity, glia and neuronal signaling. Moving forward, we consider how these mechanistic insights may inform interventions to improve brain outcomes in PWH. This review summarizes literature from clinical and preclinical studies demonstrating the adverse effects of METH, as well as the potentially beneficial effects of cannabis, on the interacting systemic (e.g., gut barrier leakage/microbial translocation, immune activation, inflammation) and CNS-specific (e.g., glial activation/neuroinflammation, neural injury, mitochondrial toxicity/oxidative stress) mechanisms underlying HIV-associated neurocognitive disorders.

Sirtuin 1-Chromatin-Binding Dynamics Points to a Common Mechanism Regulating Inflammatory Targets in SIV Infection and in the Aging Brain.

Microglia and macrophages are the main non-neuronal subsets of myeloid origin in the brain, and are critical regulators in neurodegenerative disorders, where inflammation is a key factor. Since HIV infection results in neurological perturbations that are similar to those in aging, we examined microglial and infiltrating myeloid subsets in the search for changes that might resemble the ones in aging. For that, we used the SIV infection in rhesus macaques to model neuroAIDS. We found that Sirt-1, a molecule that impacts survival and health in many models, was decreased in cell preparations containing a majority of microglia and myeloid cells from the brain of infected macaques. The role of Sirt-1 in neuroAIDS is unknown. We hypothesized that Sirt-1 silencing functions are affected by SIV. Mapping of Sirt-1 binding patterns to chromatin revealed that the number of Sirt-1-bound genes was 29.6% increased in myeloid cells from infected animals with mild or no detectable neuropathology, but 51% was decreased in severe neuropathology, compared to controls. Importantly, Sirt-1-bound genes in controls largely participate in neuroinflammation. Promoters of type I IFN pathway genes IRF7, IRF1, IFIT1, and AIF1, showed Sirt-1 binding in controls, which was consistently lost after infection, together with higher transcription. Loss of Sirt-1 binding was also found in brains from old uninfected animals, suggesting a common regulation. The role of Sirt-1 in regulating these inflammatory markers was confirmed in two different in vitro models, where Sirt-1 blockage modulated IRF7, IRF1 and AIF1 levels both in human macrophage cell lines and in human blood-derived monocytes from various normal donors, stimulated with a TLR9 agonist. Our data suggests that Sirt-1-inflammatory gene silencing is disturbed by SIV infection, resembling aging in brains. These findings may impact our knowledge on the contribution of myeloid subsets to the neurological consequences of HIV infection, aggravated and overlapping with the aging process.