Cocaine induced inflammatory response in human neuronal progenitor cells

In vitro modeling of the human dopaminergic system using spatially arranged ventral midbrain-striatum-cortex assembloids

Ventral midbrain dopaminergic neurons project to the striatum as well as the cortex and are involved in movement control and reward-related cognition. In Parkinson's disease, nigrostriatal midbrain dopaminergic neurons degenerate and cause typical Parkinson's disease motor-related impairments, while the dysfunction of mesocorticolimbic midbrain dopaminergic neurons is implicated in addiction and neuropsychiatric disorders. Study of the development and selective neurodegeneration of the human dopaminergic system, however, has been limited due to the lack of an appropriate model and access to human material. Here, we have developed a human in vitro model that recapitulates key aspects of dopaminergic innervation of the striatum and cortex. These spatially arranged ventral midbrain-striatum-cortical organoids (MISCOs) can be used to study dopaminergic neuron maturation, innervation and function with implications for cell therapy and addiction research. We detail protocols for growing ventral midbrain, striatal and cortical organoids and describe how they fuse in a linear manner when placed in custom embedding molds. We report the formation of functional long-range dopaminergic connections to striatal and cortical tissues in MISCOs, and show that injected, ventral midbrain-patterned progenitors can mature and innervate the tissue. Using these assembloids, we examine dopaminergic circuit perturbations and show that chronic cocaine treatment causes long-lasting morphological, functional and transcriptional changes that persist upon drug withdrawal. Thus, our method opens new avenues to investigate human dopaminergic cell transplantation and circuitry reconstruction as well as the effect of drugs on the human dopaminergic system.

HIV gp120 impairs nucleus accumbens neuroimmune function and dopamine D3 receptor-mediated inhibition of cocaine seeking in male rats

Cocaine Use Disorders (CUDs) are associated with an increased risk of human immunodeficiency virus (HIV) infection. Cocaine and the HIV envelope protein gp120 each induce distinct deficits to mesocorticolimbic circuit function and motivated behavior; however, little is known regarding how they interact to dysregulate these functions or how such interactions impact pharmacotherapeutic efficacy. We have previously shown that the selective, weak partial agonist of the dopamine D3 receptor (D3R), MC-25-41, attenuates cocaine-seeking behavior in male rats. Here, we sought to characterize changes in striatal neuroimmune function in gp120-exposed rats across abstinence from operant access to cocaine (0.75 mg/kg, i.v.) or sucrose (45 mg/pellet), and to examine the impact of gp120 exposure on MC-25-41-reduced cocaine seeking. After establishing a history of cocaine or sucrose self-administration, rats received intracerebroventricular gp120 infusions daily the first 5 days of abstinence and were sacrificed either on day 6 or after 21 days of forced abstinence and a cue-induced cocaine seeking test. We demonstrated that MC-25-41 treatment attenuated cue-induced cocaine seeking among control rats but not gp120-exposed rats. Moreover, postmortem analysis of nucleus accumbens (NAc) core neuroimmune function indicated cocaine abstinence- and gp120-induced impairments, and the expression of several immune factors within the NAc core significantly correlated with cocaine-seeking behavior. We conclude that cocaine abstinence dysregulates striatal neuroimmune function and interacts with gp120 to inhibit the effectiveness of a D3R partial agonist in reducing cocaine seeking. These findings highlight the need to consider comorbidities, such as immune status, when evaluating the efficacy of novel pharmacotherapeutics.

Molecular genetics of cocaine use disorders in humans

Drug addiction, one of the major health problems worldwide, is characterized by the loss of control in drug intake, craving, and withdrawal. At the individual level, drugs of abuse produce serious consequences on health and have a negative impact on the family environment and on interpersonal and work relationships. At a wider scale, they have significant socio-economic and public health consequences and they cause delinquency and citizen insecurity. Cocaine, a psychostimulant substance, is one of the most used illicit drugs, especially in America, Western Europe, and Australia. Cocaine use disorders (CUD) are complex multifactorial conditions driven by both genetic and environmental influences. Importantly, not all people who use cocaine develop CUD, and this is due, at least in part, to biological factors that are encoded in the genome of individuals. Acute and repeated use of cocaine induces epigenetic and gene expression changes responsible for the neuronal adaptations and the remodeling of brain circuits that lead to the transition from use to abuse or dependence. The purpose of this review is to delineate such factors, which should eventually help to understand the inter-individual variability in the susceptibility to cocaine addiction. Heritability estimates for CUD are high and genetic risk factors for cocaine addiction have been investigated by candidate gene association studies (CGAS) and genome-wide association studies (GWAS), reviewed here. Also, the high comorbidity that exists between CUD and several other psychiatric disorders is well known and includes phenotypes like schizophrenia, aggression, antisocial or risk-taking behaviors. Such comorbidities are associated with a worse lifetime trajectory, and here we report shared genetic factors that may contribute to them. Gene expression changes and epigenetic modifications induced by cocaine use and chronic abuse in humans are addressed by reviewing transcriptomic studies performed on neuronal cells and on postmortem brains. We report some genes which expression is altered by cocaine that also bear genetic risk variants for the disorder. Finally, we have a glance to the pharmacogenetics of CUD treatments, still in early stages. A better understanding of the genetic underpinnings of CUD will foster the search of effective treatments and help to move forward to personalized medicine.

The Challenge by Multiple Environmental and Biological Factors Induce Inflammation in Aging: Their Role in the Promotion of Chronic Disease

The aging process is driven by multiple mechanisms that lead to changes in energy production, oxidative stress, homeostatic dysregulation and eventually to loss of functionality and increased disease susceptibility. Most aged individuals develop chronic low-grade inflammation, which is an important risk factor for morbidity, physical and cognitive impairment, frailty, and death. At any age, chronic inflammatory diseases are major causes of morbimortality, affecting up to 5-8% of the population of industrialized countries. Several environmental factors can play an important role for modifying the inflammatory state. Genetics accounts for only a small fraction of chronic-inflammatory diseases, whereas environmental factors appear to participate, either with a causative or a promotional role in 50% to 75% of patients. Several of those changes depend on epigenetic changes that will further modify the individual response to additional stimuli. The interaction between inflammation and the environment offers important insights on aging and health. These conditions, often depending on the individual's sex, appear to lead to decreased longevity and physical and cognitive decline. In addition to biological factors, the environment is also involved in the generation of psychological and social context leading to stress. Poor psychological environments and other sources of stress also result in increased inflammation. However, the mechanisms underlying the role of environmental and psychosocial factors and nutrition on the regulation of inflammation, and how the response elicited for those factors interact among them, are poorly understood. Whereas certain deleterious environmental factors result in the generation of oxidative stress driven by an increased production of reactive oxygen and nitrogen species, endoplasmic reticulum stress, and inflammation, other factors, including nutrition (polyunsaturated fatty acids) and behavioral factors (exercise) confer protection against inflammation, oxidative and endoplasmic reticulum stress, and thus ameliorate their deleterious effect. Here, we discuss processes and mechanisms of inflammation associated with environmental factors and behavior, their links to sex and gender, and their overall impact on aging.

A potential role for microglia in stress- and drug-induced plasticity in the nucleus accumbens: A mechanism for stress-induced vulnerability to substance use disorder

Stress is an important risk factor for the development of substance use disorder (SUD). Exposure to both stress and drugs abuse lead to changes in synaptic plasticity and stress-induced alterations in synaptic plasticity may contribute to later vulnerability to SUD. Recent developmental neuroscience studies have identified microglia as regulators of synaptic plasticity. As both stress and drugs of abuse lead to microglial activation, we propose this as a potential mechanism underlying their ability to change synaptic plasticity. This review focuses on three components of synaptic plasticity: spine density, brain-derived neurotrophic factor (BDNF) and α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor expression. Their roles in addiction, stress, and development will be reviewed, as well as possible mechanisms by which microglia could regulate their function. Potential links between stress, vulnerability to addiction, and microglial activity will be explored.

Evaluating Angiogenic Potential of Small Molecules Using Genetic Network Approaches

Control of microvascular network growth is critical to treatment of ischemic tissue diseases and enhancing regenerative capacity of tissue engineering implants. Conventional therapeutic strategies for inducing angiogenesis aim to deliver one or more proangiogenic cytokines or to over-express known pro-angiogenic genes, but seldom address potential compensatory or cooperative effects between signals and the overarching signaling pathways that determine successful outcomes. An emerging grand challenge is harnessing the expanding knowledge base of angiogenic signaling pathways toward development of successful new therapies. We previously performed drug optimization studies by various substitutions of a 2-(2,6-dioxo-3-piperidyl)isoindole-1,3-dione scaffold to discover novel bioactive small molecules capable of inducing growth of microvascular networks, the most potent of which we termed phthalimide neovascularization factor 1 (PNF1, formerly known as SC-3–149). We then showed that PNF-1 regulates the transcription of signaling molecules that are associated with vascular initiation and maturation in a time-dependent manner through a novel pathway compendium analysis in which transcriptional regulatory networks of PNF-1-stimulated microvascular endothelial cells are overlaid with literature-derived angiogenic pathways. In this study, we generated three analogues (SC-3–143, SC-3–263, SC-3–13) through systematic transformations to PNF1 to evaluate the effects of electronic, steric, chiral, and hydrogen bonding changes on angiogenic signaling. We then expanded our compendium analysis toward these new compounds. Variables obtained from the compendium analysis were then used to construct a PLSR model to predict endothelial cell proliferation. Our combined approach suggests mechanisms of action involving suppression of VEGF pathways through TGF-β andNR3C1 network activation.

Previously, we discovered a novel small molecule (PNF1) that is capable of inducing growth of microvascular networks, a mechanism that is very important in many regenerative applications. In this study, we alter the structure of PNF1 slightly to get three different analogues and focus on gaining insight into how these drugs induce their pro-angiogenic effects. This is done through a few techniques that result in a map of all the transcripts that are up- or downregulated as a result of administering the drug, a knowledge that is necessary for successful therapeutic strategies.

Angiogenesis and neovascularization is important in a number of regenerative medicine therapeutics, including soft tissue regeneration. Having a deep understanding of the transcriptional mechanism of small molecules with this angiogenic potential will aid in designing specific immunomodulatory biomaterials. In the future, we will study these drugs and their angiogenic properties in impactful and clinically translatable applications.

Gene regulation and genetics in neurochemistry, past to future

Ask any neuroscientist to name the most profound discoveries in the field in the past 60 years, and at or near the top of the list will be a phenomenon or technique related to genes and their expression. Indeed, our understanding of genetics and gene regulation has ushered in whole new systems of knowledge and new empirical approaches, many of which could not have even been imagined prior to the molecular biology boon of recent decades. Neurochemistry, in the classic sense, intersects with these concepts in the manifestation of neuropeptides, obviously dependent upon the central dogma (the established rules by which DNA sequence is eventually converted into protein primary structure) not only for their conformation but also for their levels and locales of expression. But, expanding these considerations to non-peptide neurotransmitters illustrates how gene regulatory events impact neurochemistry in a much broader sense, extending beyond the neurochemicals that translate electrical signals into chemical ones in the synapse, to also include every aspect of neural development, structure, function, and pathology. From the beginning, the mutability - yet relative stability - of genes and their expression patterns were recognized as potential substrates for some of the most intriguing phenomena in neurobiology - those instances of plasticity required for learning and memory. Near-heretical speculation was offered in the idea that perhaps the very sequence of the genome was altered to encode memories. A fascinating component of the intervening progress includes evidence that the central dogma is not nearly as rigid and consistent as we once thought. And this mutability extends to the potential to manipulate that code for both experimental and clinical purposes. Astonishing progress has been made in the molecular biology of neurochemistry during the 60 years since this journal debuted. Many of the gains in conceptual understanding have been driven by methodological progress, from automated high-throughput sequencing instruments to recombinant-DNA vectors that can convey color-coded genetic modifications in the chromosomes of live adult animals. This review covers the highlights of these advances, both theoretical and technological, along with a brief window into the promising science ahead. This article is part of the 60th Anniversary special issue.

Transcriptomic and genetic studies identify NFAT5 as a candidate gene for cocaine dependence

Cocaine reward and reinforcing effects are mediated mainly by dopaminergic neurotransmission. In this study, we aimed at evaluating gene expression changes induced by acute cocaine exposure on SH-SY5Y-differentiated cells, which have been widely used as a dopaminergic neuronal model. Expression changes and a concomitant increase in neuronal activity were observed after a 5 μM cocaine exposure, whereas no changes in gene expression or in neuronal activity took place at 1 μM cocaine. Changes in gene expression were identified in a total of 756 genes, mainly related to regulation of transcription and gene expression, cell cycle, adhesion and cell projection, as well as mitogen-activeated protein kinase (MAPK), CREB, neurotrophin and neuregulin signaling pathways. Some genes displaying altered expression were subsequently targeted with predicted functional single-nucleotide polymorphisms (SNPs) in a case-control association study in a sample of 806 cocaine-dependent patients and 817 controls. This study highlighted associations between cocaine dependence and five SNPs predicted to alter microRNA binding at the 3'-untranslated region of the NFAT5 gene. The association of SNP rs1437134 with cocaine dependence survived the Bonferroni correction for multiple testing. A functional effect was confirmed for this variant by a luciferase reporter assay, with lower expression observed for the rs1437134G allele, which was more pronounced in the presence of hsa-miR-509. However, brain volumes in regions of relevance to addiction, as assessed with magnetic resonance imaging, did not correlate with NFAT5 variation. These results suggest that the NFAT5 gene, which is upregulated a few hours after cocaine exposure, may be involved in the genetic predisposition to cocaine dependence.

Cocaine induces nuclear export and degradation of neuronal retinoid X receptor-γ via a TNF-α/JNK- mediated mechanism

Cocaine abuse represents an immense societal health and economic burden for which no effective treatment currently exists. Among the numerous intracellular signaling cascades impacted by exposure to cocaine, increased and aberrant production of pro-inflammatory cytokines in the CNS has been observed. Additionally, we have previously reported a decrease in retinoid-X-receptor-gamma (RXR-γ) in brains of mice chronically exposed to cocaine. Through obligate heterodimerization with a number of nuclear receptors, RXRs serve as master regulatory transcription factors, which can potentiate or suppress expression of a wide spectrum of genes. Little is known about the regulation of RXR levels, but previous studies indicate cellular stressors such as cytokines negatively regulate levels of RXRs in vitro. To evaluate the mechanism underlying the cocaine-induced decreases in RXR-γ levels observed in vivo, we exposed neurons to cocaine in vitro and examined pathways which may contribute to disruption in RXR signaling, including activation of stress pathways by cytokine induction. In these studies, we provide the first evidence that cocaine exposure disrupts neuronal RXR-γ signaling in vitro by promoting its nuclear export and degradation. Furthermore, we demonstrate this effect may be mediated, at least in part, by cocaine-induced production of TNF-α and its downstream effector c-Jun-NH-terminal kinase (JNK). Findings from this study are therefore applicable to both cocaine abuse and to pathological conditions characterized by neuroinflammatory factors, such as neurodegenerative disease.

Peripheral toxicity in crack cocaine use disorders

A growing body of evidence suggests that crack cocaine misuse has widespread systemic and cognitive consequences, but little attention has been given to its systemic pathophysiology. We report here changes in inflammation markers, oxidative damage and brain derived neurotrophic factor in a sample of outpatients with crack cocaine use disorders. Fifty-three outpatients were recruited for this cross-sectional study and matched with fifty control subjects. The focus of this report is in between group differences in cytokines, oxidative damage and brain-derived neurotrophic factor (BDNF). Crack cocaine use was associated with higher BDNF levels when compared to controls, present only in those who used crack cocaine in the last month. Patients also had higher circulating levels of IL-1β, TNF-α and IL-10 when compared to controls. There were no significant differences in oxidative damage between patients and controls. These results represent a first demonstration that crack cocaine use disorders entail an activation of the reward, immune and inflammatory systems.

Impact of opiate addiction on neuroinflammation in HIV

To investigate the independent and interactive effects of opiate addiction and HIV on neuroinflammation, we measured microglial/macrophage activation and astrogliosis in multiple regions of human brain. Samples of thalamus, frontal gray matter, and frontal white matter were obtained from 46 individuals categorized as: HIV negatives, HIV-negative opiate addicts, HIV positives, HIV-positive opiate addicts, HIV encephalitis (HIVE), and HIVE opiate addicts. Activated brain microglia/macrophages and astrocytosis were quantified by morphometric analysis of immunohistochemical stains for CD68, HLA-D, CD163, and GFAP. The effects of HIV grouping, opiate addiction, and their interaction on expression of the markers were examined in a series of two-way ANOVAs. In opiate addicts, there was generally higher baseline expression of CD68 and HLA-D in HIV negatives, and lower expression in HIV and HIVE, compared to individuals without opiate abuse. Thus, for these markers, and for GFAP in frontal gray, opiates were associated with attenuated HIV effect. In contrast, for CD163, opiates did not significantly alter responses to HIV, and HIV effects were variably absent in individuals without opiate abuse. The divergent impact that opiate addiction displays on these markers may suggest a generally immunosuppressive role in the CNS, with decreased HIV-associated activation of markers CD68 and HLA-D that potentially reflect neurotoxic pathways, and preservation of CD163, thought to be an indicator of neuroprotective scavenger systems. These results suggest a complex impact of opiates on neuroinflammation in baseline and virally stimulated states.

Dietary restriction mitigates cocaine-induced alterations of olfactory bulb cellular plasticity and gene expression, and behavior

Because the olfactory system plays a major role in food consumption, and because 'food addiction' and associated morbidities have reached epidemic proportions, we tested the hypothesis that dietary energy restriction can modify adverse effects of cocaine on behavior and olfactory cellular and molecular plasticity. Mice maintained on an alternate day fasting (ADF) diet exhibited increased baseline locomotion and increased cocaine-sensitized locomotion during cocaine conditioning, despite no change in cocaine conditioned place preference, compared with mice fed ad libitum. Levels of dopamine and its metabolites in the olfactory bulb (OB) were suppressed in mice on the ADF diet compared with mice on the control diet, independent of acute or chronic cocaine treatment. The expression of several enzymes involved in dopamine metabolism including tyrosine hydroxylase, monoamine oxidases A and B, and catechol-O-methyltransferase were significantly reduced in OBs of mice on the ADF diet. Both acute and chronic administration of cocaine suppressed the production of new OB cells, and this effect of cocaine was attenuated in mice on the ADF diet. Cocaine administration to mice on the control diet resulted in up-regulation of OB genes involved in mitochondrial energy metabolism, synaptic plasticity, cellular stress responses, and calcium- and cAMP-mediated signaling, whereas multiple olfactory receptor genes were down-regulated by cocaine treatment. ADF abolished many of the effects of cocaine on OB gene expression. Our findings reveal that dietary energy intake modifies the neural substrates underlying some of the behavioral and physiological responses to repeated cocaine treatment, and also suggest novel roles for the olfactory system in addiction. The data further suggest that modification of dietary energy intake could provide a novel potential approach to addiction treatments.

Mechanistic exploration of phthalimide neovascular factor 1 using network analysis tools

Neovascularization is essential for the survival and successful integration of most engineering tissues after implantation in vivo. The objective of this study was to elucidate possible mechanisms of phthalimide neovascular factor 1 (PNF1), a new synthetic small molecule proposed for therapeutic induction of angiogenesis. Complementary deoxyribonucleic acid microarray analysis was used to identify 568 transcripts in human microvascular endothelial cells (HMVECs) that were significantly regulated after 24-h stimulation with 30 muM of PNF1, previously known as SC-3-149. Network analysis tools were used to identify genetic networks of the global biological processes involved in PNF1 stimulation and to describe known molecular and cellular functions that the drug regulated most highly. Examination of the most significantly perturbed networks identified gene products associated with transforming growth factor-beta (TGF-beta), which has many known effects on angiogenesis, and related signal transduction pathways. These include molecules integral to the thrombospondin, plasminogen, fibroblast growth factor, epidermal growth factor, ephrin, Rho, and Ras signaling pathways that are essential to endothelial function. Moreover, real-time reverse-transcriptase polymerase chain reaction (RT-PCR) of select genes showed significant increases in TGF-beta-associated receptors endoglin and beta glycan. These experiments provide important insight into the pro-angiogenic mechanism of PNF1, namely, TGF-beta-associated signaling pathways, and may ultimately offer new molecular targets for directed drug discovery.

Cocaine-induced oxidative stress precedes cell death in human neuronal progenitor cells

By 2003, an estimated 34 million Americans had used cocaine according to the National Survey on Drug Use & Health. About 5.9 million of those had used in the past 12 months. Chronic cocaine users often develop addiction, dependency and tolerance to the drug. The psychological and physical effects of cocaine are due to the disruption of the limbic system in the central nervous system (CNS). Increased oxidative stress reported in the frontal cortex and the striatum of rats exposed to cocaine suggests that oxidative damage plays a significant role in cocaine-induced disruption of the CNS. Although it is evident that cocaine induces oxidative stress in the CNS, little has been learned about whether such increased oxidative stress is also relevant to apoptosis in cocaine-exposed models. To gain insight into the role of cocaine-induced oxidative stress in apoptosis, we hypothesized that oxidative stress precedes cell death when cocaine is administrated. To test this hypothesis, we have monitored the oxidative stress and apoptotic effects of acute cocaine exposure in human neuronal progenitor cells (HNPC). We found that oxidative stress was significantly increased at 48h after a 30min cocaine exposure compared to control cells, and that this was followed by cell death at 72h. Using the same experimental paradigm we have previously shown that pro-inflammatory genes are up-regulated in cocaine-exposed HNPC at 24h. Therefore, we suggest that the increased oxidative stress (possibly mediated by inflammatory responses) precedes cell death in cocaine-exposed HNPC. This may have implications for the consequences of cocaine abuse in situations where antioxidant capacity is compromised, as in the aging brain.