Up-regulation of microRNAs in brain of human alcoholics

MicroRNA Nobel Prize: Timely Recognition and High Anticipation of Future Products-A Prospective Analysis

MicroRNAs (miRNAs) maintain cellular homeostasis by blocking mRNAs by binding with them to fine-tune the expression of genes across numerous biological pathways. The 2024 Nobel Prize in Medicine and Physiology for discovering miRNAs was long overdue. We anticipate a deluge of research work involving miRNAs to repeat the history of prizes awarded for research on other RNAs. Although miRNA therapies are included for several complex diseases, the realization that miRNAs regulate genes and their roles in addressing therapies for hundreds of diseases are expected; but with advancement in drug discovery tools, we anticipate even faster entry of new drugs. To promote this, we provide details of the current science, logic, intellectual property, formulations, and regulatory process with anticipation that many more researchers will introduce novel therapies based on the discussion and advice provided in this paper.

Human genetics and epigenetics of alcohol use disorder

Alcohol use disorder (AUD) is a prominent contributor to global morbidity and mortality. Its complex etiology involves genetics, epigenetics, and environmental factors. We review progress in understanding the genetics and epigenetics of AUD, summarizing the key findings. Advancements in technology over the decades have elevated research from early candidate gene studies to present-day genome-wide scans, unveiling numerous genetic and epigenetic risk factors for AUD. The latest GWAS on more than one million participants identified more than 100 genetic variants, and the largest epigenome-wide association studies (EWAS) in blood and brain samples have revealed tissue-specific epigenetic changes. Downstream analyses revealed enriched pathways, genetic correlations with other traits, transcriptome-wide association in brain tissues, and drug-gene interactions for AUD. We also discuss limitations and future directions, including increasing the power of GWAS and EWAS studies as well as expanding the diversity of populations included in these analyses. Larger samples, novel technologies, and analytic approaches are essential; these include whole-genome sequencing, multiomics, single-cell sequencing, spatial transcriptomics, deep-learning prediction of variant function, and integrated methods for disease risk prediction.

Alcohol, HMGB1, and Innate Immune Signaling in the Brain

PURPOSE

Binge drinking (i.e., consuming enough alcohol to achieve a blood ethanol concentration of 80 mg/dL, approximately 4-5 drinks within 2 hours), particularly in early adolescence, can promote progressive increases in alcohol drinking and alcohol-related problems that develop into compulsive use in the chronic relapsing disease, alcohol use disorder (AUD). Over the past decade, neuroimmune signaling has been discovered to contribute to alcohol-induced changes in drinking, mood, and neurodegeneration. This review presents a mechanistic hypothesis supporting high mobility group box protein 1 (HMGB1) and Toll-like receptor (TLR) signaling as key elements of alcohol-induced neuroimmune signaling across glia and neurons, which shifts gene transcription and synapses, altering neuronal networks that contribute to the development of AUD. This hypothesis may help guide further research on prevention and treatment.

SEARCH METHODS

The authors used the search terms "HMGB1 protein," "alcohol," and "brain" across PubMed, Scopus, and Embase to find articles published between 1991 and 2023.

SEARCH RESULTS

The database search found 54 references in PubMed, 47 in Scopus, and 105 in Embase. A total of about 100 articles were included.

DISCUSSION AND CONCLUSIONS

In the brain, immune signaling molecules play a role in normal development that differs from their functions in inflammation and the immune response, although cellular receptors and signaling are shared. In adults, pro-inflammatory signals have emerged as contributing to brain adaptation in stress, depression, AUD, and neurodegenerative diseases. HMGB1, a cytokine-like signaling protein released from activated cells, including neurons, is hypothesized to activate pro-inflammatory signals through TLRs that contribute to adaptations to binge and chronic heavy drinking. HMGB1 alone and in heteromers with other molecules activates TLRs and other immune receptors that spread signaling across neurons and glia. Both blood and brain levels of HMGB1 increase with ethanol exposure. In rats, an adolescent intermittent ethanol (AIE) binge drinking model persistently increases brain HMGB1 and its receptors; alters microglia, forebrain cholinergic neurons, and neuronal networks; and increases alcohol drinking and anxiety while disrupting cognition. Studies of human postmortem AUD brain have found elevated levels of HMGB1 and TLRs. These signals reduce cholinergic neurons, whereas microglia, the brain's immune cells, are activated by binge drinking. Microglia regulate synapses through complement proteins that can change networks affected by AIE that increase drinking, contributing to risks for AUD. Anti-inflammatory drugs, exercise, cholinesterase inhibitors, and histone deacetylase epigenetic inhibitors prevent and reverse the AIE-induced pathology. Further, HMGB1 antagonists and other anti-inflammatory treatments may provide new therapies for alcohol misuse and AUD. Collectively, these findings suggest that restoring the innate immune signaling balance is central to recovering from alcohol-related pathology.

Toll-like receptor 7: A novel neuroimmune target to reduce excessive alcohol consumption

Toll-like receptors (TLRs) are a family of innate immune receptors that recognize molecular patterns in foreign pathogens and intrinsic danger/damage signals from cells. TLR7 is a nucleic acid sensing endosomal TLR that is activated by single-stranded RNAs from microbes or by small noncoding RNAs that act as endogenous ligands. TLR7 signals through the MyD88 adaptor protein and activates the transcription factor interferon regulatory factor 7 (IRF7). TLR7 is found throughout the brain and is highly expressed in microglia, the main immune cells of the brain that have also been implicated in alcohol drinking in mice. Upregulation of TLR7 mRNA and protein has been identified in postmortem hippocampus and cortex from AUD subjects that correlated positively with lifetime consumption of alcohol. Similarly, Tlr7 and downstream signaling genes were upregulated in rat hippocampal and cortical slice cultures after chronic alcohol exposure and in these regions after chronic binge-like alcohol treatment in mice. In addition, repeated administration of the synthetic TLR7 agonists imiquimod (R837) or resiquimod (R848) increased voluntary alcohol drinking in different rodent models and produced sustained upregulation of IRF7 in the brain. These findings suggest that chronic TLR7 activation may drive excessive alcohol drinking. In the brain, this could occur through increased levels of endogenous TLR7 activators, like microRNAs and Y RNAs. This review explores chronic TLR7 activation as a pathway of dysregulated neuroimmune signaling in AUD and the endogenous small RNA ligands in the brain that could perpetuate innate immune responses and escalate alcohol drinking.

Alcohol: Epigenome alteration and inter/transgenerational effect

While DNA serves as the fundamental genetic blueprint for an organism, it is not a static entity. Gene expression, the process by which genetic information is utilized to create functional products like proteins, can be modulated by a diverse range of environmental factors. Epigenetic mechanisms, including DNA methylation, histone modification, and microRNAs, play a pivotal role in mediating the intricate interplay between the environment and gene expression. Intriguingly, alterations in the epigenome have the potential to be inherited across generations. Alcohol use disorder (AUD) poses significant health issues worldwide. Alcohol has the capability to induce changes in the epigenome, which can be inherited by offspring, thus impacting them even in the absence of direct alcohol exposure. This review delves into the impact of alcohol on the epigenome, examining how its effects vary based on factors such as the age of exposure (adolescence or adulthood), the duration of exposure (chronic or acute), and the specific sample collected (brain, blood, or sperm). The literature underscores that alcohol exposure can elicit diverse effects on the epigenome during different life stages. Furthermore, compelling evidence from human and animal studies demonstrates that alcohol induces alterations in epigenome content, affecting both the brain and blood. Notably, rodent studies suggest that these epigenetic changes can result in lasting phenotype alterations that extend across at least two generations. In conclusion, the comprehensive literature analysis supports the notion that alcohol exposure induces lasting epigenetic alterations, influencing the behavior and health of future generations. This knowledge emphasizes the significance of addressing the potential transgenerational effects of alcohol and highlights the importance of preventive measures to minimize the adverse impact on offspring.

Neuron enriched extracellular vesicles' MicroRNA expression profiles as a marker of early life alcohol consumption

Alcohol consumption may impact and shape brain development through perturbed biological pathways and impaired molecular functions. We investigated the relationship between alcohol consumption rates and neuron-enriched extracellular vesicles' (EVs') microRNA (miRNA) expression to better understand the impact of alcohol use on early life brain biology. Neuron-enriched EVs' miRNA expression was measured from plasma samples collected from young people using a commercially available microarray platform while alcohol consumption was measured using the Alcohol Use Disorders Identification Test. Linear regression and network analyses were used to identify significantly differentially expressed miRNAs and to characterize the implicated biological pathways, respectively. Compared to alcohol naïve controls, young people reporting high alcohol consumption exhibited significantly higher expression of three neuron-enriched EVs' miRNAs including miR-30a-5p, miR-194-5p, and miR-339-3p, although only miR-30a-5p and miR-194-5p survived multiple test correction. The miRNA-miRNA interaction network inferred by a network inference algorithm did not detect any differentially expressed miRNAs with a high cutoff on edge scores. However, when the cutoff of the algorithm was reduced, five miRNAs were identified as interacting with miR-194-5p and miR-30a-5p. These seven miRNAs were associated with 25 biological functions; miR-194-5p was the most highly connected node and was highly correlated with the other miRNAs in this cluster. Our observed association between neuron-enriched EVs' miRNAs and alcohol consumption concurs with results from experimental animal models of alcohol use and suggests that high rates of alcohol consumption during the adolescent/young adult years may impact brain functioning and development by modulating miRNA expression.

Influence of sex and liver cirrhosis on the expression of miR-146a-5p and its target genes, IRAK1 and TRAF6

Long-term alcohol misuse triggers cellular adaptions in susceptible regions of the human brain, resulting in neurodegeneration, neuroinflammation and altered gene expression. Previous studies have identified ∼35 miRNAs, including miR-146a-5p, which are up-regulated in the frontal cortex of males with alcohol use disorder (AUD), but the influence of liver cirrhosis and sex is unknown. The expression of miR-146a-5p, IRAK1, and TRAF6 was measured in the prefrontal cortex of controls and individuals with AUD with and without cirrhosis of the liver. Further, individuals were genotyped for two SNPs, rs2910164 and rs57095329. The expression of miR-146a-5p was significantly different between sexes. In males the expression of miR-146a-5p was increased in individuals with AUD with and without liver cirrhosis compared with controls. In females miR-146a-5p expression was significantly lower in individuals with AUD compared with both controls and those with AUD and cirrhosis, suggesting that both the severity of alcohol misuse and the sex of the individual influences the expression of miR-146a-5p. The expression of TRAF6 was significantly lower in individuals with uncomplicated AUD compared with those with AUD and cirrhosis. The expression of IRAK1 did not differ between groups or sexes. There was no influence of genotype on expression. Increased expression of miR-146a-5p did not correlate with decreased IRAK1 or TRAF6 expression suggesting a loss of regulatory control of the TLR4 pathway. Understanding sex-specific differences in the regulation of gene expression in AUD is key to determine which inflammatory pathways could be targeted for therapeutic intervention.

miRNAs and Substances Abuse: Clinical and Forensic Pathological Implications: A Systematic Review

Substance addiction is a chronic and relapsing brain disorder characterized by compulsive seeking and continued substance use, despite adverse consequences. The high prevalence and social burden of addiction are indisputable; however, the available intervention is insufficient. The modulation of gene expression and aberrant adaptation of neural networks are attributed to the changes in brain functions under repeated exposure to addictive substances. Considerable studies have demonstrated that miRNAs are strong modulators of post-transcriptional gene expression in substance addiction. The emerging role of microRNA (miRNA) provides new insights into many biological and pathological processes in the central nervous system: their variable expression in different regions of the brain and tissues may play a key role in regulating the pathophysiological events of addiction. This work provides an overview of the current literature on miRNAs involved in addiction, evaluating their impaired expression and regulatory role in neuroadaptation and synaptic plasticity. Clinical implications of such modulatory capacities will be estimated. Specifically, it will evaluate the potential diagnostic role of miRNAs in the various stages of drug and substance addiction. Future perspectives about miRNAs as potential novel therapeutic targets for substance addiction and abuse will also be provided.

Addictive drugs modify neurogenesis, synaptogenesis and synaptic plasticity to impair memory formation through neurotransmitter imbalances and signaling dysfunction

Drug abuse changes neurophysiological functions at multiple cellular and molecular levels in the addicted brain. Well-supported scientific evidence suggests that drugs negatively affect memory formation, decision-making and inhibition, and emotional and cognitive behaviors. The mesocorticolimbic brain regions are involved in reward-related learning and habitual drug-seeking/taking behaviors to develop physiological and psychological dependence on the drugs. This review highlights the importance of specific drug-induced chemical imbalances resulting in memory impairment through various neurotransmitter receptor-mediated signaling pathways. The mesocorticolimbic modifications in the expression levels of brain-derived neurotrophic factor (BDNF) and the cAMP-response element binding protein (CREB) impair reward-related memory formation following drug abuse. The contributions of protein kinases and microRNAs (miRNAs), along with the transcriptional and epigenetic regulation have also been considered in memory impairment underlying drug addiction. Overall, we integrate the research on various types of drug-induced memory impairment in distinguished brain regions and provide a comprehensive review with clinical implications addressing the upcoming studies.

Discerning the Prospects of miRNAs as a Multi-Target Therapeutic and Diagnostic for Alzheimer's Disease

Although over the last few decades, numerous attempts have been made to halt Alzheimer's disease (AD) progression and mitigate its symptoms, only a few have been proven beneficial. Most medications available, still only cater to the symptoms of the disease rather than fixing the cause at the root level. A novel approach involving the use of miRNAs, which work on the principle of gene silencing, is being explored by scientists. Naturally present miRNAs in the biological system help to regulate various genes than may be implicated in AD-like BACE-1 and APP. One miRNA thus, holds the power to keep a check on several genes, conferring it the ability to be used as a multi-target therapeutic. With aging and the onset of diseased pathology, dysregulation of these miRNAs is observed. This flawed miRNA expression is responsible for the unusual buildup of amyloid proteins, fibrillation of tau proteins in the brain, neuronal death and other hallmarks leading to AD. The use of miRNA mimics and miRNA inhibitors provides an attractive perspective for fixing the upregulation and downregulation of miRNAs that led to abnormal cellular activities. Furthermore, the detection of miRNAs in the CSF and serum of diseased patients might be considered an earlier biomarker for the disease. While most of the therapies designed around AD have not succeeded completely, the targeting of dysregulated miRNAs in AD patients might give a new direction to scholars to develop an effective treatment for Alzheimer's disease.

Imaging the brain's immune response to alcohol with [11C]PBR28 TSPO Positron Emission Tomography

In humans, the negative effects of alcohol are linked to immune dysfunction in both the periphery and the brain. Yet acute effects of alcohol on the neuroimmune system and its relationships with peripheral immune function are not fully understood. To address this gap, immune response to an alcohol challenge was measured with positron emission tomography (PET) using the radiotracer [11C]PBR28, which targets the 18-kDa translocator protein, a marker sensitive to immune challenges. Participants (n = 12; 5 F; 25-45 years) who reported consuming binge levels of alcohol (>3 drinks for females; >4 drinks for males) 1-3 months before scan day were enrolled. Imaging featured a baseline [11C]PBR28 scan followed by an oral laboratory alcohol challenge over 90 min. An hour later, a second [11C]PBR28 scan was acquired. Dynamic PET data were acquired for at least 90 min with arterial blood sampling to measure the metabolite-corrected input function. [11C]PBR28 volume of distributions (VT) was estimated in the brain using multilinear analysis 1. Subjective effects, blood alcohol levels (BAL), and plasma cytokines were measured during the paradigm. Full completion of the alcohol challenge and data acquisition occurred for n = 8 (2 F) participants. Mean peak BAL was 101 ± 15 mg/dL. Alcohol significantly increased brain [11C]PBR28 VT (n = 8; F(1,49) = 34.72, p > 0.0001; Cohen's d'=0.8-1.7) throughout brain by 9-16%. Alcohol significantly altered plasma cytokines TNF-α (F(2,22) = 17.49, p < 0.0001), IL-6 (F(2,22) = 18.00, p > 0.0001), and MCP-1 (F(2,22) = 7.02, p = 0.004). Exploratory analyses identified a negative association between the subjective degree of alcohol intoxication and changes in [11C]PBR28 VT. These findings provide, to our knowledge, the first in vivo human evidence for an acute brain immune response to alcohol.

A systematic review of non-coding RNA genes with differential expression profiles associated with autism spectrum disorders

AIMS

To identify differential expression of shorter non-coding RNA (ncRNA) genes associated with autism spectrum disorders (ASD).

BACKGROUND

ncRNA are functional molecules that derive from non-translated DNA sequence. The HUGO Gene Nomenclature Committee (HGNC) have approved ncRNA gene classes with alignment to the reference human genome. One subset is microRNA (miRNA), which are highly conserved, short RNA molecules that regulate gene expression by direct post-transcriptional repression of messenger RNA. Several miRNA genes are implicated in the development and regulation of the nervous system. Expression of miRNA genes in ASD cohorts have been examined by multiple research groups. Other shorter classes of ncRNA have been examined less. A comprehensive systematic review examining expression of shorter ncRNA gene classes in ASD is timely to inform the direction of research.

METHODS

We extracted data from studies examining ncRNA gene expression in ASD compared with non-ASD controls. We included studies on miRNA, piwi-interacting RNA (piRNA), small NF90 (ILF3) associated RNA (snaR), small nuclear RNA (snRNA), small nucleolar RNA (snoRNA), transfer RNA (tRNA), vault RNA (vtRNA) and Y RNA. The following electronic databases were searched: Cochrane Library, EMBASE, PubMed, Web of Science, PsycINFO, ERIC, AMED and CINAHL for papers published from January 2000 to May 2022. Studies were screened by two independent investigators with a third resolving discrepancies. Data was extracted from eligible papers.

RESULTS

Forty-eight eligible studies were included in our systematic review with the majority examining miRNA gene expression alone. Sixty-four miRNA genes had differential expression in ASD compared to controls as reported in two or more studies, but often in opposing directions. Four miRNA genes had differential expression in the same direction in the same tissue type in at least 3 separate studies. Increased expression was reported in miR-106b-5p, miR-155-5p and miR-146a-5p in blood, post-mortem brain, and across several tissue types, respectively. Decreased expression was reported in miR-328-3p in bloods samples. Seven studies examined differential expression from other classes of ncRNA, including piRNA, snRNA, snoRNA and Y RNA. No individual ncRNA genes were reported in more than one study. Six studies reported differentially expressed snoRNA genes in ASD. A meta-analysis was not possible because of inconsistent methodologies, disparate tissue types examined, and varying forms of data presented.

CONCLUSION

There is limited but promising evidence associating the expression of certain miRNA genes and ASD, although the studies are of variable methodological quality and the results are largely inconsistent. There is emerging evidence associating differential expression of snoRNA genes in ASD. It is not currently possible to say whether the reports of differential expression in ncRNA may relate to ASD aetiology, a response to shared environmental factors linked to ASD such as sleep and nutrition, other molecular functions, human diversity, or chance findings. To improve our understanding of any potential association, we recommend improved and standardised methodologies and reporting of raw data. Further high-quality research is required to shine a light on possible associations, which may yet yield important information.

Neuron Enriched Exosomal MicroRNA Expression Profiles as a Marker of Early Life Alcohol Consumption

Background

Alcohol consumption may impact and shape brain development through perturbed biological pathways and impaired molecular functions. We investigated the relationship between alcohol consumption rates and neuron-enriched exosomal microRNA (miRNA) expression to better understand the impact of alcohol use on early life brain biology.

Methods

Neuron-enriched exosomal miRNA expression was measured from plasma samples collected from young people using a commercially available microarray platform while alcohol consumption was measured using the Alcohol Use Disorders Identification Test. Linear regression and network analyses were used to identify significantly differentially expressed miRNAs and to characterize the implicated biological pathways, respectively.

Results

Compared to alcohol naïve controls, young people reporting high alcohol consumption exhibited significantly higher expression of four neuron-enriched exosomal miRNAs including miR-30a-5p, miR-194-5p, and miR-339-3p, although only miR-30a-5p and miR-194-5p survived multiple test correction. The miRNA-miRNA interaction network inferred by a network inference algorithm did not detect any differentially expressed miRNAs with a high cutoff on edge scores. However, when the cutoff of the algorithm was reduced, five miRNAs were identified as interacting with miR-194-5p and miR-30a-5p. These seven miRNAs were associated with 25 biological functions; miR-194-5p was the most highly connected node and was highly correlated with the other miRNAs in this cluster.

Conclusions

Our observed association between neuron-enriched exosomal miRNAs and alcohol consumption concurs with results from experimental animal models of alcohol use and suggests that high rates of alcohol consumption during the adolescent/young adult years may impact brain functioning and development by modulating miRNA expression.

miRNA Expression Analysis of the Hippocampus in a Vervet Monkey Model of Fetal Alcohol Spectrum Disorder Reveals a Potential Role in Global mRNA Downregulation

MicroRNAs (miRNAs) are short-length non-protein-coding RNA sequences that post-transcriptionally regulate gene expression in a broad range of cellular processes including neuro- development and have previously been implicated in fetal alcohol spectrum disorders (FASD). In this study, we use our vervet monkey model of FASD to follow up on a prior multivariate (developmental age × ethanol exposure) mRNA analysis (GSE173516) to explore the possibility that the global mRNA downregulation we observed in that study could be related to miRNA expression and function. We report here a predominance of upregulated and differentially expressed miRNAs. Further, the 24 most upregulated miRNAs were significantly correlated with their predicted targets (Target Scan 7.2). We then explored the relationship between these 24 miRNAs and the fold changes observed in their paired mRNA targets using two prediction platforms (Target Scan 7.2 and miRwalk 3.0). Compared to a list of non-differentially expressed miRNAs from our dataset, the 24 upregulated and differentially expressed miRNAs had a greater impact on the fold changes of their corresponding mRNA targets across both platforms. Taken together, this evidence raises the possibility that ethanol-induced upregulation of specific miRNAs might contribute functionally to the general downregulation of mRNAs observed by multiple investigators in response to prenatal alcohol exposure.

Alcohol reverses the effects of KCNJ6 (GIRK2) noncoding variants on excitability of human glutamatergic neurons

Synonymous and noncoding single nucleotide polymorphisms (SNPs) in the KCNJ6 gene, encoding G protein-gated inwardly rectifying potassium channel subunit 2 (GIRK2), have been linked with increased electroencephalographic frontal theta event-related oscillations (ERO) in subjects diagnosed with alcohol use disorder (AUD). To identify molecular and cellular mechanisms while retaining the appropriate genetic background, we generated induced excitatory glutamatergic neurons (iN) from iPSCs derived from four AUD-diagnosed subjects with KCNJ6 variants ("Affected: AF") and four control subjects without variants ("Unaffected: UN"). Neurons were analyzed for changes in gene expression, morphology, excitability and physiological properties. Single-cell RNA sequencing suggests that KCNJ6 AF variant neurons have altered patterns of synaptic transmission and cell projection morphogenesis. Results confirm that AF neurons express lower levels of GIRK2, have greater neurite area, and elevated excitability. Interestingly, exposure to intoxicating concentrations of ethanol induces GIRK2 expression and reverses functional effects in AF neurons. Ectopic overexpression of GIRK2 alone mimics the effect of ethanol to normalize induced excitability. We conclude that KCNJ6 variants decrease GIRK2 expression and increase excitability and that this effect can be minimized or reduced with ethanol.

Epigenetic Dysregulation in Alcohol-Associated Behaviors: Preclinical and Clinical Evidence

Alcohol use disorder (AUD) is characterized by loss of control over intake and drinking despite harmful consequences. At a molecular level, AUD is associated with long-term neuroadaptations in key brain regions that are involved in reward processing and decision-making. Over the last decades, a great effort has been made to understand the neurobiological basis underlying AUD. Epigenetic mechanisms have emerged as an important mechanism in the regulation of long-term alcohol-induced gene expression changes. Here, we review the literature supporting a role for epigenetic processes in AUD. We particularly focused on the three most studied epigenetic mechanisms: DNA methylation, Histone modification and non-coding RNAs. Clinical studies indicate an association between AUD and DNA methylation both at the gene and global levels. Using behavioral paradigms that mimic some of the characteristics of AUD, preclinical studies demonstrate that changes in epigenetic mechanisms can functionally impact alcohol-associated behaviors. While many studies support a therapeutic potential for targeting epigenetic enzymes, more research is needed to fully understand their role in AUD. Identification of brain circuits underlying alcohol-associated behaviors has made major advances in recent years. However, there are very few studies that investigate how epigenetic mechanisms can affect these circuits or impact the neuronal ensembles that promote alcohol-associated behaviors. Studies that focus on the role of circuit-specific and cell-specific epigenetic changes for clinically relevant alcohol behaviors may provide new insights on the functional role of epigenetic processes in AUD.

Functional roles, regulatory mechanisms and theranostics applications of ncRNAs in alcohol use disorder

Alcohol use disorder (AUD) is one of the most prevalent neuropsychological disorders worldwide, and its pathogenesis is convoluted and poorly understood. There is considerable evidence demonstrating significant associations between multiple heritable factors and the onset and progression of AUD. In recent years, a substantial body of research conducted by emerging biotechnologies has increasingly highlighted the crucial roles of noncoding RNAs (ncRNAs) in the pathophysiology of mental diseases. As in-depth understanding of ncRNAs and their mechanisms of action, they have emerged as prospective diagnostic indicators and preclinical therapeutic targets for a variety of psychiatric illness, including AUD. Of note, dysregulated expression of ncRNAs such as circRNAs, lncRNAs and miRNAs was routinely found in AUD individuals, and besides, exogenous regulation of partial ncRNAs has also been shown to be effective in ameliorating alcohol preference and excessive alcohol consumption. However, the exact molecular mechanism still remains elusive. Herein, we systematically summarized current knowledge regarding alterations in the expression of certain ncRNAs as well as their-mediated regulatory mechanisms in individuals with AUD. And finally, we detailedly reviewed the potential theranostics applications of gene therapy agents targeting ncRNAs in AUD mice. Overall, a deeper comprehension of functional roles and biological mechanisms of ncRNAs may make significant contributions to the accurate diagnosis and effective treatment of AUD.

Noncoding RNA therapeutics for substance use disorder

Although noncoding RNAs (ncRNAs) have been shown to regulate maladaptive neuroadaptations that drive compulsive drug use, ncRNA-targeting therapeutics for substance use disorder (SUD) have yet to be clinically tested. Recent advances in RNA-based drugs have improved many therapeutic issues related to immune response, specificity, and delivery, leading to multiple successful clinical trials for other diseases. As the need for safe and effective treatments for SUD continues to grow, novel nucleic acid-based therapeutics represent an appealing approach to target ncRNA mechanisms in SUD. Here, we review ncRNA processes implicated in SUD, discuss recent therapeutic approaches for targeting ncRNAs, and highlight potential opportunities and challenges of ncRNA-targeting therapeutics for SUD.

Revealing genetic links of Type 2 diabetes that lead to the development of Alzheimer's disease

Background

A factor leading to Alzheimer's Disease (AD), portrayed by peripheral insulin resistance, is Type 2 diabetes mellitus (T2D). The likelihood of T2D cases would be at boosted danger in alternating AD cases has severe social consequences. Several genes have been detected via gene expression profiling or different techniques; despite the consideration of the utility of numerous of these genes stays insufficient.

Methods

This project is designed to uncover the mutual genomics motifs between AD and T2D via non-negative matrix factorization (NMF) of differentially expressed genes (DEGs) of T2D Mellitus of human cortical neurons of the neurovascular unit gene expression data. A rank factorization value is calculated by employing the combination of the NMF model with the unit invariant knee (UIK) point method. The metagenes are further determined by remarking the enriched Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and gene ontology (GO) enrichment tools. In this study, the most highly expressed genes of metagenes are subjected to protein-protein interaction (PPI) network study to discover the most significant biomarkers of T2D Mellitus in the ageing brain.

Results

We screened the most important shared genes (CDKN1A, COL22A1, EIF4A, GFAP, SLC1A1, and VIM) and essential human molecular pathways that motivate these diseases. The study aimed to validate the most significant hub genes using network-based methods which detected the corresponding relationship between AD and T2D.

Conclusions

Using in silico tools, the computational pipeline has broadly examined transformed pathways and discovered promising biomarkers and drug targets. We validated the most significant hub genes using network-based methods which detected the corresponding relationship between AD and T2D. These consequences on brain cells hypothetically reserve to diabetic Alzheimer's so-called type 3 diabetes (T3D) and may offer promising methodologies for curative intrusion.

RNA biomarkers for alcohol use disorder

Alcohol use disorder (AUD) is highly prevalent and one of the leading causes of disability in the US and around the world. There are some molecular biomarkers of heavy alcohol use and liver damage which can suggest AUD, but these are lacking in sensitivity and specificity. AUD treatment involves psychosocial interventions and medications for managing alcohol withdrawal, assisting in abstinence and reduced drinking (naltrexone, acamprosate, disulfiram, and some off-label medications), and treating comorbid psychiatric conditions (e.g., depression and anxiety). It has been suggested that various patient groups within the heterogeneous AUD population would respond more favorably to specific treatment approaches. For example, there is some evidence that so-called reward-drinkers respond better to naltrexone than acamprosate. However, there are currently no objective molecular markers to separate patients into optimal treatment groups or any markers of treatment response. Objective molecular biomarkers could aid in AUD diagnosis and patient stratification, which could personalize treatment and improve outcomes through more targeted interventions. Biomarkers of treatment response could also improve AUD management and treatment development. Systems biology considers complex diseases and emergent behaviors as the outcome of interactions and crosstalk between biomolecular networks. A systems approach that uses transcriptomic (or other -omic data, e.g., methylome, proteome, metabolome) can capture genetic and environmental factors associated with AUD and potentially provide sensitive, specific, and objective biomarkers to guide patient stratification, prognosis of treatment response or relapse, and predict optimal treatments. This Review describes and highlights state-of-the-art research on employing transcriptomic data and artificial intelligence (AI) methods to serve as molecular biomarkers with the goal of improving the clinical management of AUD. Considerations about future directions are also discussed.

Plasma MicroRNA Signature of Alcohol Consumption: The Rotterdam Study

BACKGROUND

MicroRNAs (miRNAs) represent a class of noncoding RNAs that regulate gene expression and are implicated in the pathogenesis of different diseases. Alcohol consumption might affect the expression of miRNAs, which in turn could play a role in risk of diseases.

OBJECTIVES

We investigated whether plasma concentrations of miRNAs are altered by alcohol consumption. Given the existing evidence showing the link between alcohol and liver diseases, we further explored the extent to which these associations are mediated by miRNAs.

METHODS

Profiling of plasma miRNAs was conducted using the HTG EdgeSeq miRNA Whole Transcriptome Assay in 1933 participants of the Rotterdam Study. Linear regression was implemented to explore the link between alcohol consumption (glasses/d) and miRNA concentrations, adjusted for age, sex, cohort, BMI, and smoking. Sensitivity analysis for alcohol categories (nondrinkers, light drinkers, and heavy drinkers) was performed, where light drinkers corresponded to 0-2 glasses/d in men and 0-1 glasses/d in women, and heavy drinkers to >2 glasses/d in men and >1 glass/d in women. Moreover, we utilized the alcohol-associated miRNAs to explore their potential mediatory role between alcohol consumption and liver-related traits. Finally, we retrieved putative target genes of identified miRNAs to gain an understanding of the molecular pathways concerning alcohol consumption.

RESULTS

Plasma concentrations of miR-193b-3p, miR-122-5p, miR-3937, and miR-4507 were significantly associated with alcohol consumption surpassing the Bonferroni-corrected P < 8.46 × 10-5. The top significant association was observed for miR-193b-3p (β = 0.087, P = 2.90 × 10-5). Furthermore, a potential mediatory role of miR-3937 and miR-122-5p was observed between alcohol consumption and liver traits. Pathway analysis of putative target genes revealed involvement in biological regulation and cellular processes.

CONCLUSIONS

This study indicates that alcohol consumption is associated with plasma concentrations of 4 miRNAs. We outline a potential mediatory role of 2 alcohol-associated miRNAs (miR-3937 and miR-122-5p), laying the groundwork for further exploration of miRNAs as potential mediators between lifestyle factors and disease development.

Postnatal Foxp2 regulates early psychiatric-like phenotypes and associated molecular alterations in the R6/1 transgenic mouse model of Huntington's disease

Huntington's Disease (HD) is a devastating disorder characterized by a triad of motor, psychiatric and cognitive manifestations. Psychiatric and emotional symptoms appear at early stages of the disease which are consistently described by patients and caregivers among the most disabling. Here, we show for the first time that Foxp2 is strongly associated with some psychiatric-like disturbances in the R6/1 mouse model of HD. First, 4-week-old (juvenile) R6/1 mice behavioral phenotype was characterized by an increased impulsive-like behavior and less aggressive-like behavior. In this line, we identified an early striatal downregulation of Foxp2 protein starting as soon as at postnatal day 15 that could explain such deficiencies. Interestingly, the rescue of striatal Foxp2 levels from postnatal stages completely reverted the impulsivity-phenotype and partially the social impairments concomitant with a rescue of dendritic spine pathology. A mass spectrometry study indicated that the rescue of spine loss was associated with an improvement of several altered proteins related with cytoskeleton dynamics. Finally, we reproduced and mimicked the impulsivity and social deficits in wild type mice by reducing their striatal Foxp2 expression from postnatal stages. Overall, these results imply that early postnatal reduction of Foxp2 might contribute to the appearance of some of the early psychiatric symptoms in HD.

Nanoparticle delivery systems for substance use disorder

Innovative breakthroughs in nanotechnology are having a substantial impact in healthcare, especially for brain diseases where effective therapeutic delivery systems are desperately needed. Nanoparticle delivery systems offer an unmatched ability of not only conveying a diverse array of diagnostic and therapeutic agents across complex biological barriers, but also possess the ability to transport payloads to targeted cell types over a sustained period. In substance use disorder (SUD), many therapeutic targets have been identified in preclinical studies, yet few of these findings have been translated to effective clinical treatments. The lack of success is, in part, due to the significant challenge of delivering novel therapies to the brain and specific brain cells. In this review, we evaluate the potential approaches and limitations of nanotherapeutic brain delivery systems. We also highlight the examples of promising strategies and future directions of nanocarrier-based treatments for SUD.

Non-Invasive microRNA Profiling in Saliva can Serve as a Biomarker of Alcohol Exposure and Its Effects in Humans

Alcohol Use Disorder (AUD) is one of the most prevalent mental disorders worldwide. Considering the widespread occurrence of AUD, a reliable, cheap, non-invasive biomarker of alcohol consumption is desired by healthcare providers, clinicians, researchers, public health and criminal justice officials. microRNAs could serve as such biomarkers. They are easily detectable in saliva, which can be sampled from individuals in a non-invasive manner. Moreover, microRNAs expression is dynamically regulated by environmental factors, including alcohol. Since excessive alcohol consumption is a hallmark of alcohol abuse, we have profiled microRNA expression in the saliva of chronic, heavy alcohol abusers using microRNA microarrays. We observed significant changes in salivary microRNA expression caused by excessive alcohol consumption. These changes fell into three categories: downregulated microRNAs, upregulated microRNAs, and microRNAs upregulated de novo. Analysis of these combinatorial changes in microRNA expression suggests dysregulation of specific biological pathways leading to impairment of the immune system and development of several types of epithelial cancer. Moreover, some of the altered microRNAs are also modulators of inflammation, suggesting their contribution to pro-inflammatory mechanisms of alcohol actions. Establishment of the cellular source of microRNAs in saliva corroborated these results. We determined that most of the microRNAs in saliva come from two types of cells: leukocytes involved in immune responses and inflammation, and buccal cells, involved in development of epithelial, oral cancers. In summary, we propose that microRNA profiling in saliva can be a useful, non-invasive biomarker allowing the monitoring of alcohol abuse, as well as alcohol-related inflammation and early detection of cancer.

Current and Future Perspectives of Noncoding RNAs in Brain Function and Neuropsychiatric Disease

Noncoding RNAs (ncRNAs) represent the majority of the transcriptome and play important roles in regulating neuronal functions. ncRNAs are exceptionally diverse in both structure and function and include enhancer RNAs, long ncRNAs, and microRNAs, all of which demonstrate specific temporal and regional expression in the brain. Here, we review recent studies demonstrating that ncRNAs modulate chromatin structure, act as chaperone molecules, and contribute to synaptic remodeling and behavior. In addition, we discuss ncRNA function within the context of neuropsychiatric diseases, particularly focusing on addiction and schizophrenia, and the recent methodological developments that allow for better understanding of ncRNA function in the brain. Overall, ncRNAs represent an underrecognized molecular contributor to complex neuronal processes underlying neuropsychiatric disorders.

The Role of miRNAs as New Molecular Biomarkers for Dating the Age of Wound Production: A Systematic Review

BACKGROUND

The timing of wounds production is a significant issue in forensic pathology. Although various methods have been evaluated, obtaining an accurate dating of lesions is still a challenge. The pathologist uses many parameters to value wound age, such as histological and immunohistochemical. In recent years, there have been many studies regarding the use of miRNAs in wound-age estimation; indeed, miRNAs have multiple potential uses in forensic pathology.

SCOPE

This review aims to verify the efficacy and feasibility of miRNAs as a tool for determining the timing of lesions.

MATERIALS AND METHODS

The authors conducted the systematic review according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. PubMed was used as a search engine to find articles published between January, 1st 2016 and October, 1st 2021, to evaluate the current state of the art regarding wound-age estimation.

RESULTS

A total of 256 articles were collected; after screening according to PRISMA guidelines, the systematic review included 8 articles. The studies included in this review were all Original articles evaluating the use of biomarkers for wound-age determination.

DISCUSSION AND CONCLUSION

The literature review showed that analysis of miRNA is an innovative field of study with significant potentiality in forensic pathology. There are few studies, and almost all of them are at an early stage. The challenge is to understand how to standardize the samples' selection to obtain reliable experimental data. This observation represents a necessary prerequisite to planning further clinical trials.

Non-coding RNA in alcohol use disorder by affecting synaptic plasticity

Alcohol use disorder (AUD) is one of the most serious public health problems worldwide. AUD is a complex disorder, and there is ample evidence that genetic predisposition is critical to its development. Recent studies have shown that genetic predisposition leads to the onset of AUD, and alcohol metabolism can affect epigenetic inheritance, which in turn affects synaptic plasticity, alters brain function, and leads to more severe addictive behaviors. Non-coding RNAs (ncRNAs), especially microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), play an important role in alcohol addiction. This paper reviews the regulatory role of ncRNAs. ncRNAs are involved in enzyme and neurotransmitter reaction systems during alcohol use disorder. Alcohol consumption regulates the expression of ncRNAs that mediate epigenetic modification and synaptic plasticity, which play an important role in the development of chronic AUD. ncRNAs may be used not only as predictors of therapeutic responses but also as therapeutic targets of AUD. Chronic alcoholism is more likely to lead to neuroimmune disorders, including permanent brain dysfunction. AUD induced by long-term alcoholism greatly alters the expression of genes in the human genome, especially the expression of ncRNAs. Alcohol can cause a series of pathological changes by interfering with gene expression, such as through disordered miRNA-mRNA expression networks, epigenetic modifications, disordered metabolism, and even synaptic remodeling. ncRNAs are involved in the transition from moderate drinking to alcohol dependence.

Astroglia in the Vulnerability and Maintenance of Alcohol Use Disorders

Changes induced in the morphology and the multiplicity of functional roles played by astrocytes in brain regions critical to the establishment and maintenance of alcohol abuse suggest that they make an important contribution to the vulnerability to alcohol use disorders. The understanding of the relevant mechanisms accounting for that contribution is complicated by the fact that alcohol itself acts directly on astrocytes altering their metabolism, gene expression, and plasticity, so that the ultimate result is a complex interaction of various cellular pathways, including intracellular calcium regulation, neuroimmune responses, and regulation of neurotransmitter and gliotransmitter release and uptake. The recent years have seen a steady increase in the characterization of several of the relevant mechanisms, but much remains to be done for a full understanding of the astrocytes' contribution to the vulnerability to alcohol dependence and abuse and for using that knowledge in designing effective therapies for AUDs.

Epigenetic modification in alcohol use disorder and alcoholic cardiomyopathy: From pathophysiology to therapeutic opportunities

Alcohol consumption prompts detrimental psychological, pathophysiological and health issues, representing one of the major causes of death worldwide. Alcohol use disorder (AUD), which is characterized by compulsive alcohol intake and loss of control over alcohol usage, arises from a complex interplay between genetic and environmental factors. More importantly, long-term abuse of alcohol is often tied with unfavorable cardiac remodeling and contractile alterations, a cadre of cardiac responses collectively known as alcoholic cardiomyopathy (ACM). Recent evidence has denoted a pivotal role for ethanol-triggered epigenetic modifications, the interface between genome and environmental cues, in the organismal and cellular responses to ethanol exposure. To-date, three major epigenetic mechanisms (DNA methylation, histone modifications, and RNA-based mechanisms) have been identified for the onset and development of AUD and ACM. Importantly, these epigenetic changes induced by alcohol may be detectable in the blood, thus offering diagnostic, therapeutic, and prognostic promises of epigenetic markers for AUD and alcoholic complications. In addition, several epigenetic drugs have shown efficacies in the management of alcohol abuse, loss of control for alcohol usage, relapse, drinking-related anxiety and behavior in withdrawal. In this context, medications targeting epigenetic modifications may hold promises for pharmaceutical management of AUD and ACM.

Identifying a novel biological mechanism for alcohol addiction associated with circRNA networks acting as potential miRNA sponges

Our lab and others have shown that chronic alcohol use leads to gene and miRNA expression changes across the mesocorticolimbic (MCL) system. Circular RNAs (circRNAs) are noncoding RNAs that form closed-loop structures and are reported to alter gene expression through miRNA sequestration, thus providing a potentially novel neurobiological mechanism for the development of alcohol dependence (AD). Genome-wide expression of circRNA was assessed in the nucleus accumbens (NAc) from 32 AD-matched cases/controls. Significant circRNAs (unadj. p ≤ 0.05) were identified via regression and clustered in circRNA networks via weighted gene co-expression network analysis (WGCNA). CircRNA interactions with previously generated mRNA and miRNA were detected via correlation and bioinformatic analyses. Significant circRNAs (N = 542) clustered in nine significant AD modules (FWER p ≤ 0.05), within which we identified 137 circRNA hubs. We detected 23 significant circRNA-miRNA-mRNA interactions (FDR ≤ 0.10). Among these, circRNA-406742 and miR-1200 significantly interact with the highest number of mRNA, including genes associated with neuronal functioning and alcohol addiction (HRAS, PRKCB, HOMER1, and PCLO). Finally, we integrate genotypic information that revealed 96 significant circRNA expression quantitative trait loci (eQTLs) (unadj. p ≤ 0.002) that showed significant enrichment within recent alcohol use disorder (AUD) and smoking genome-wide association study (GWAS). To our knowledge, this is the first study to examine the role of circRNA in the neuropathology of AD. We show that circRNAs impact mRNA expression by interacting with miRNA in the NAc of AD subjects. More importantly, we provide indirect evidence for the clinical importance of circRNA in the development of AUD by detecting a significant enrichment of our circRNA eQTLs among GWAS of substance abuse.

Exploration of alcohol use disorder-associated brain miRNA-mRNA regulatory networks

Transcriptomic changes in specific brain regions can influence the risk of alcohol use disorder (AUD), but the underlying mechanism is not fully understood. We investigated AUD-associated miRNA-mRNA regulatory networks in multiple brain regions by analyzing transcriptomic changes in two sets of postmortem brain tissue samples and ethanol-exposed human embryonic stem cell (hESC)-derived cortical interneurons. miRNA and mRNA transcriptomes were profiled in 192 tissue samples (Set 1) from eight brain regions (amygdala, caudate nucleus, cerebellum, hippocampus, nucleus accumbens, prefrontal cortex, putamen, and ventral tegmental area) of 12 AUD and 12 control European Australians. Nineteen differentially expressed miRNAs (fold-change>2.0 & P < 0.05) and 97 differentially expressed mRNAs (fold-change>2.0 & P < 0.001) were identified in one or multiple brain regions of AUD subjects. AUD-associated miRNA-mRNA regulatory networks in each brain region were constructed using differentially expressed and negatively correlated miRNA-mRNA pairs. AUD-relevant pathways (including CREB Signaling, IL-8 Signaling, and Axonal Guidance Signaling) were potentially regulated by AUD-associated brain miRNA-mRNA pairs. Moreover, miRNA and mRNA transcriptomes were mapped in additional 96 tissue samples (Set 2) from six of the above eight brain regions of eight AUD and eight control European Australians. Some of the AUD-associated miRNA-mRNA regulatory networks were confirmed. In addition, miRNA and mRNA transcriptomes were analyzed in hESC-derived cortical interneurons with or without ethanol exposure, and ethanol-influenced miRNA-mRNA regulatory networks were constructed. This study provided evidence that alcohol could induce concerted miRNA and mRNA expression changes in reward-related or alcohol-responsive brain regions. We concluded that altered brain miRNA-mRNA regulatory networks might contribute to AUD development.

Alcohol induced impairment/abnormalities in brain: Role of MicroRNAs

Alcohol is a highly toxic substance and has teratogenic properties that can lead to a wide range of developmental disorders. Excessive use of alcohol can change the structural and functional aspects of developed brain and other organs. Which can further lead to significant health, social and economic implications in many countries of the world. Convincing evidence support the involvement of microRNAs (miRNAs) as important post-transcriptional regulators of gene expression in neurodevelopment and maintenance. They also show differential expression following an injury. MiRNAs are the special class of small non coding RNAs that can modify the gene by targeting the mRNA and fine tune the development of cells to organs. Numerous pieces of evidences have shown the relationship between miRNA, alcohol and brain damage. These studies also show how miRNA controls different cellular mechanisms involved in the development of alcohol use disorder. With the increasing number of research studies, the roles of miRNAs following alcohol-induced injury could help researchers to recognize alternative therapeutic methods to treat/cure alcohol-induced brain damage. The present review summarizes the available data and brings together the important miRNAs, that play a crucial role in alcohol-induced brain damage, which will help in better understanding complex mechanisms. Identifying these miRNAs will not only expand the current knowledge but can lead to the identification of better targets for the development of novel therapeutic interventions.

The importance of non-coding RNAs in environmental stress-related developmental brain disorders: A systematic review of evidence associated with exposure to alcohol, anesthetic drugs, nicotine, and viral infections

Brain development is a dynamic and lengthy process that includes cell proliferation, migration, neurogenesis, gliogenesis, synaptogenesis, and pruning. Disruption of any of these developmental events can result in long-term outcomes ranging from brain structural changes, to cognitive and behavioral abnormality, with the mechanisms largely unknown. Emerging evidence suggests non-coding RNAs (ncRNAs) as pivotal molecules that participate in normal brain development and neurodevelopmental disorders. NcRNAs such as long non-coding RNAs (lncRNAs) and microRNAs (miRNAs) are transcribed from the genome but not translated into proteins. Many ncRNAs have been implicated as tuners of cell fate. In this review, we started with an introduction of the current knowledge of lncRNAs and miRNAs, and their potential roles in brain development in health and disorders. We then reviewed and discussed the evidence of ncRNA involvement in abnormal brain development resulted from alcohol, anesthetic drugs, nicotine, and viral infections. The complex connections among these ncRNAs were also discussed, along with potential overlapping ncRNA mechanisms, possible pharmacological targets for therapeutic/neuroprotective interventions, and potential biomarkers for brain developmental disorders.

Biogenesis, physiological functions and potential applications of extracellular vesicles in substance use disorders

Substance use disorder (SUD) is a growing health problem that affects several millions of people worldwide, resulting in negative socioeconomic impacts and increased health care costs. Emerging evidence suggests that extracellular vesicles (EVs) play a crucial role in SUD pathogenesis. EVs, including exosomes and microvesicles, are membrane-encapsulated particles that are released into the extracellular space by most types of cells. EVs are important players in mediating cell-to-cell communication through transfer of cargo such as proteins, lipids and nucleic acids. The EV cargo can alter the status of recipient cells, thereby contributing to both physiological and pathological processes; some of these play critical roles in SUD. Although the functions of EVs under several pathological conditions have been extensively reviewed, EV functions and potential applications in SUD remain less studied. In this review, we provide an overview of the current knowledge of the role of EVs in SUD, including alcohol, cocaine, heroin, marijuana, nicotine and opiate abuse. The review will focus on the biogenesis and cargo composition of EVs as well as the potential use of EVs as biomarkers of SUD or therapeutic targets in SUD.

High ethanol preference and dissociated memory are co-occurring phenotypes associated with hippocampal GABAAR-δ receptor levels

Alcohol use disorder (AUD) frequently co-occurs with dissociative disorders and disorders with dissociative symptoms, suggesting a common neurobiological basis. It has been proposed that facilitated information processing under the influence of alcohol, resulting in the formation of dissociated memories, might be an important factor controlling alcohol use. Access to such memories is facilitated under the effect of alcohol, thus further reinforcing alcohol use. To interrogate possible mechanisms associated with these phenotypes, we used a mouse model of dissociative amnesia, combined with a high-alcohol preferring (HAP) model of AUD. Dissociated memory was induced by activation of hippocampal extrasynaptic GABA type A receptor delta subunits (GABA_AR-δ), which control tonic inhibition and to which ethanol binds with high affinity. Increased ethanol preference was associated with increased propensity to form dissociated memories dependent on GABA_AR-δ in the dorsal hippocampus (DH). Furthermore, the DH level of GABA_AR-δ protein, but not mRNA, was increased in HAP mice, and was inversely correlated to the level of miR-365-3p, suggesting an miRNA-mediated post-transcriptional mechanism contributing to elevated GABA_AR-δ. The observed changes of DH GABA_AR-δ were associated with a severe reduction of excitatory projections stemming from GABA_AR-δ-containing pyramidal neurons in the subiculum and terminating in the mammillary body. These results suggest that both molecular and circuit dysfunction involving hippocampal GABA_AR-δ receptors might contribute to the co-occurrence of ethanol preference and dissociated information processing.

Role of microRNAs in the pathophysiology of addiction

Addiction is a chronic and relapsing brain disorder characterized by compulsive seeking despite adverse consequences. There are both heritable and epigenetic mechanisms underlying drug addiction. Emerging evidence suggests that non-coding RNAs (ncRNAs) such as microRNAs (miRNAs), long non-coding RNAs, and circular RNAs regulate synaptic plasticity and related behaviors caused by substances of abuse. These ncRNAs modify gene expression and may contribute to the behavioral phenotypes of addiction. Among the ncRNAs, the most widely researched and impactful are miRNAs. The goal in this systematic review is to provide a detailed account of recent research involving the role of miRNAs in addiction. This article is categorized under: RNA Interactions with Proteins and Other Molecules > Small Molecule-RNA Interactions RNA in Disease and Development > RNA in Disease.

MicroRNA regulation of prefrontal cortex development and psychiatric risk in adolescence

In this review, we examine the role of microRNAs in the development of the prefrontal cortex (PFC) in adolescence and in individual differences in vulnerability to mental illness. We describe results from clinical and preclinical research indicating that adolescence coincides with drastic changes in local microRNA expression, including microRNAs that control gene networks involved in PFC and cognitive refinement. We highlight that altered levels of microRNAs in the PFC are associated with psychopathologies of adolescent onset, notably depression and schizophrenia. We show that microRNAs can be measured non-invasively in peripheral samples and could serve as longitudinal physiological readouts of brain expression and psychiatric risk in youth.

Targets and regulation of microRNA-652-3p in homoeostasis and disease

microRNA are small non-coding RNA molecules which inhibit gene expression by binding mRNA, preventing its translation. As important regulators of gene expression, there is increasing interest in microRNAs as potential diagnostic biomarkers and therapeutic targets. Studies investigating the role of one of the miRNA-miR-652-3p-detail diverse roles for this miRNA in normal cell homoeostasis and disease states, including cancers, cardiovascular disease, mental health, and central nervous system diseases. Here, we review recent literature surrounding miR-652-3p, discussing its known target genes and their relevance to disease progression. These studies demonstrate that miR-652-3p targets LLGL1 and ZEB1 to modulate cell polarity mechanisms, with impacts on cancer metastasis and asymmetric cell division. Inhibition of the NOTCH ligand JAG1 by miR-652-3p can have diverse effects on angiogenesis and immune cell regulation. Investigation of miR-652-3p and other dysregulated miRNAs identified a number of pathways potentially regulated by miR-652-3p. This review demonstrates that miR-652-3p has great promise as a diagnostic or therapeutic target due to its activity across multiple cellular systems.

TRAIL Mediates Neuronal Death in AUD: A Link between Neuroinflammation and Neurodegeneration

Although the cause of progressive neurodegeneration is often unclear, neuronal death can occur through several mechanisms. In conditions such as Alzheimer's or alcohol use disorder (AUD), Toll-like receptor (TLR) induction is observed with neurodegeneration. However, links between TLR activation and neurodegeneration are lacking. We report a role of apoptotic neuronal death in AUD through TLR7-mediated induction of death receptor signaling. In postmortem human cortex, a two-fold increase in apoptotic terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) staining in neurons was found in AUD versus controls. This occurred with the increased expression of TLR7 and tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) death receptors. Binge ethanol treatment in C57BL/6 mice increased TLR7 and induced neuronal apoptosis in cortical regions that was blocked by TLR7 antagonism. Mechanistic studies in primary organotypic brain slice culture (OBSC) found that the inhibition of TLR7 and its endogenous ligand let-7b blocked ethanol-induced neuronal cell death. Both IMQ and ethanol induced the expression of TRAIL and its death receptor. In addition, TRAIL-neutralizing monoclonal antibodies blocked both imiquimod (IMQ) and ethanol induced neuronal death. These findings implicate TRAIL as a mediator of neuronal apoptosis downstream of TLR7 activation. TLR7 and neuronal apoptosis are implicated in other neurodegenerative diseases, including Alzheimer's disease. Therefore, TRAIL may represent a therapeutic target to slow neurodegeneration in multiple diseases.

Alcohol Use Disorder is Associated with Upregulation of MicroRNA-34a and MicroRNA-34c in Hippocampal Postmortem Tissue

BACKGROUND

To investigate epigenetic mechanisms potentially involved in the cognitive decline associated with chronic alcohol intake, we evaluated the expressions of three micro-RNAs (miR-34a, -34b, and -34c) highly expressed in the hippocampus and involved in neuronal physiology and pathology. MiR-34a participates in functioning and survival of mature neurons; miR-34b is associated with Alzheimer-like disorders; and miR-34c is implicated in the memory impairment of Alzheimer disease in rodents and humans.

METHODS

A total of 69 cases were selected from the Biobank for Aging Studies and categorized according to the absence (n = 50) or presence (n = 19) of alcohol use disorder (AUD). Cases presenting with neuropathological diagnoses of dementias were excluded. Total RNA was extracted from hippocampal paraffinized slices, complementary DNA was synthesized from miRs, and RT-qPCR was performed with TaqMan^® assays.

RESULTS

Higher expressions of miR-34a and miR-34c, but not of miR-34b, were found in the group with AUD in comparison with the group without AUD after adjustment for potential confounders (age, sex, body mass index, presence of hypertension, diabetes mellitus, smoking, and physical inactivity).

CONCLUSIONS

Hippocampal upregulation of miR-34a and miR-34c may be involved in the cognitive decline associated with chronic alcohol consumption.

Increased Expression of Plasma miRNA-320a and let-7b-5p in Heroin-Dependent Patients and Its Clinical Significance

Heroin use disorder is a chronic and relapsing disease that induces persistent changes in the brain. The diagnoses of heroin use disorders are mainly based on subjective reports and no valid biomarkers available. Recent researches have revealed that circulating miRNAs are useful non-invasive biomarkers for diagnosing brain diseases such as Alzheimer's disease, multiple sclerosis, schizophrenia, and bipolar disorder. However, studies on circulating miRNAs for the diagnosis of heroin use disorders are rarely reported. In this study, we investigated the differential expression of plasma miRNAs in 57 heroin-dependent patients. Based on literature research and microarray analysis, two candidate miRNAs, miR-320a and let-7b-5p, were selected and analyzed by quantitative real-time RT-PCR. The results showed miR-320a and let-7b were significantly upregulated in plasma of the heroin-dependent patients compared to that in healthy controls. The area under curves (AUCs) of receiver operating characteristic (ROC) curves of miR-320a and let-7b-5p were 0.748 and 0.758, respectively. The sensitivities of miR-320a and let-7b-5p were 71.9 and 70.2%, while the specificities of miR-320a and let-7b-5p were 76.1 and 78.3%, respectively. The combination of these two miRNAs predicted heron dependence with an AUC of 0.782 (95% CI 0.687-0.876), with 73.7% sensitivity and 82.6% specificity. Our findings suggest a potential use for circulating miRNAs as biomarkers for the diagnosis of heroin abuse.

Epigenetic and non-coding regulation of alcohol abuse and addiction

Alcohol use disorder is a chronic debilitated condition adversely affecting the lives of millions of individuals throughout the modern world. Individuals suffering from an alcohol use disorder diagnosis frequently have serious cooccurring conditions, which often further exacerbates problematic drinking behavior. Comprehending the biochemical processes underlying the progression and perpetuation of disease is essential for mitigating maladaptive behavior in order to restore both physiological and psychological health. The range of cellular and biological systems contributing to, and affected by, alcohol use disorder and other comorbid disorders necessitates a fundamental grasp of intricate functional relationships that govern molecular biology. Epigenetic factors are recognized as essential mediators of cellular behavior, orchestrating a symphony of gene expression changes within multicellular environments that are ultimately responsible for directing human behavior. Understanding the epigenetic and transcriptional regulatory mechanisms involved in the pathogenesis of disease is important for improving available pharmacotherapies and reducing the incidence of alcohol abuse and cooccurring conditions.

Investigating the influence of perinatal nicotine and alcohol exposure on the genetic profiles of dopaminergic neurons in the VTA using miRNA-mRNA analysis

Nicotine and alcohol are two of the most commonly used and abused recreational drugs, are often used simultaneously, and have been linked to significant health hazards. Furthermore, patients diagnosed with dependence on one drug are highly likely to be dependent on the other. Several studies have shown the effects of each drug independently on gene expression within many brain regions, including the ventral tegmental area (VTA). Dopaminergic (DA) neurons of the dopamine reward pathway originate from the VTA, which is believed to be central to the mechanism of addiction and drug reinforcement. Using a well-established rat model for both nicotine and alcohol perinatal exposure, we investigated miRNA and mRNA expression of dopaminergic (DA) neurons of the VTA in rat pups following perinatal alcohol and joint nicotine-alcohol exposure. Microarray analysis was then used to profile the differential expression of both miRNAs and mRNAs from DA neurons of each treatment group to further explore the altered genes and related biological pathways modulated. Predicted and validated miRNA-gene target pairs were analyzed to further understand the roles of miRNAs within these networks following each treatment, along with their post transcription regulation points affecting gene expression throughout development. This study suggested that glutamatergic synapse and axon guidance pathways were specifically enriched and many miRNAs and genes were significantly altered following alcohol or nicotine-alcohol perinatal exposure when compared to saline control. These results provide more detailed insight into the cell proliferation, neuronal migration, neuronal axon guidance during the infancy in rats in response to perinatal alcohol/ or nicotine-alcohol exposure.

Oxidative Stress and Neuroinflammation as a Pivot in Drug Abuse. A Focus on the Therapeutic Potential of Antioxidant and Anti-Inflammatory Agents and Biomolecules

Drug abuse is a major global health and economic problem. However, there are no pharmacological treatments to effectively reduce the compulsive use of most drugs of abuse. Despite exerting different mechanisms of action, all drugs of abuse promote the activation of the brain reward system, with lasting neurobiological consequences that potentiate subsequent consumption. Recent evidence shows that the brain displays marked oxidative stress and neuroinflammation following chronic drug consumption. Brain oxidative stress and neuroinflammation disrupt glutamate homeostasis by impairing synaptic and extra-synaptic glutamate transport, reducing GLT-1, and system X_c⁻ activities respectively, which increases glutamatergic neurotransmission. This effect consolidates the relapse-promoting effect of drug-related cues, thus sustaining drug craving and subsequent drug consumption. Recently, promising results as experimental treatments to reduce drug consumption and relapse have been shown by (i) antioxidant and anti-inflammatory synthetic molecules whose effects reach the brain; (ii) natural biomolecules secreted by mesenchymal stem cells that excel in antioxidant and anti-inflammatory properties, delivered via non-invasive intranasal administration to animal models of drug abuse and (iii) potent anti-inflammatory microRNAs and anti-miRNAs which target the microglia and reduce neuroinflammation and drug craving. In this review, we address the neurobiological consequences of brain oxidative stress and neuroinflammation that follow the chronic consumption of most drugs of abuse, and the current and potential therapeutic effects of antioxidants and anti-inflammatory agents and biomolecules to reduce these drug-induced alterations and to prevent relapse.

Increased expression of plasma hsa-miR-181a in male patients with heroin addiction use disorder

BACKGROUND

Drug addiction is an uncontrolled, chronic, and recurrent encephalopathy that presently lacks specific and characteristic biomarkers for diagnosis and treatment. As regulators of gene expression, microRNAs (miRNAs) are increasingly used for diagnostic and prognostic purposes in various disease states. Previous studies indicated that miRNAs play important roles in the development and progression of drug addictions, including addiction to methamphetamine, cocaine, alcohol, and heroin.

METHODS

We identified significant miRNAs using the microarray method and then validated the hsa-miR-181a expression levels in 53 heroin addiction patients and 49 normal controls using quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR). Finally, the potential associations between transcriptional levels in heroin addiction patients and their clinicopathological features were analyzed.

RESULTS

A total of 2006 miRNAs were differentially expressed between heroin addiction patients and normal controls. The top 10 up-regulated miRNAs in patients were hsa-miR-21a, hsa-miR-181a, hsa-miR-4459, hsa-miR-4430, hsa-miR-4306, hsa-miR-22-3P, hsa-miR-486-5P, hsa-miR-371b-5P, hsa-miR-92a-3P, and hsa-miR-5001-5P. The top 10 down-regulated miRNAs in patients were hsa-miR-3195, hsa-miR-4767, hsa-miR-3135b, hsa-miR-6087, hsa-miR-1181, hsa-miR-4785, hsa-miR-718, hsa-miR-3141, hsa-miR-652-5P, and hsa-miR-6126. The expression level of hsa-miR-181a in heroin addiction patients was significantly increased compared with that in normal controls (P < .001). The area under the receiver operating characteristic curve of hsa-miR-181a was 0.783, the sensitivity was 0.867, and the specificity was 0.551.

CONCLUSIONS

The increased expression of hsa-miR-181a in the plasma of heroin patients may be a consequence of the pathological process of heroin abuse. This study highlights the potential of hsa-miR-181a as a novel biomarker for the diagnosis of heroin addiction.

Lentiviral-mediated up-regulation of let-7d microRNA decreases alcohol intake through down-regulating the dopamine D3 receptor

Recent studies have shown that Lethal-7 (let-7) microRNA (miRNA) is involved in a wide range of psychiatric disorders such as anxiety, depression, schizophrenia, and cocaine addiction. However, the exact role of let-7d miRNA in regulating ethanol intake and preference remains to be elucidated. The aim of the present study was to clarify the role of accumbal let-7d in controlling ethanol-related behaviors in adult rats. For this purpose, stereotaxic injections of let-7d-overexpressing lentiviral vectors (LV) were administered bilaterally into the nucleus accumbens (Nacc) of Wistar rats. The ethanol-related behaviors were investigated using the two-bottle choice (TBC) access paradigm, in which the rats had access to 2.5, 5, and 10% ethanol solutions, the grid hanging test (GHT) and ethanol-induced loss-of-righting-reflex (LORR) test. The results showed that intra-accumbally administered let-7d-overexpressing LV significantly decreased ethanol intake and preference without having significant effects on body weight, consumption or preference for tastants (saccharin and quinine) or ethanol metabolism. Furthermore, accumbal let-7d increased resistance to ethanol-induced sedation in the GHT and LORR test. Most importantly, the data showed that the dopamine D3 receptor (D3R) was a candidate target of let-7d In fact, and using real time PCR, let-7d was found to directly target D3R mRNA to decrease its expression. Further analyses proved that D3R expression was negatively correlated with the levels of let-7d and ethanol-related behaviors parameters. Taken together, the data indicating that let-7d impaired ethanol-related behaviors by targeting D3R will open up new exciting possibilities and might provide potential therapeutic evidence for alcoholism.

Regulation of GABAA Receptor Subunit Expression in Substance Use Disorders

The modulation of neuronal cell firing is mediated by the release of the neurotransmitter GABA (γ-aminobuytric acid), which binds to two major families of receptors. The ionotropic GABAA receptors (GABA_ARs) are composed of five distinct subunits that vary in expression by brain region and cell type. The action of GABA on GABA_ARs is modulated by a variety of clinically and pharmacologically important drugs such as benzodiazepines and alcohol. Exposure to and abuse of these substances disrupts homeostasis and induces plasticity in GABAergic neurotransmission, often via the regulation of receptor expression. Here, we review the regulation of GABA_AR subunit expression in adaptive and pathological plasticity, with a focus on substance use. We examine the factors influencing the expression of GABA_AR subunit genes including the regulation of the 5′ and 3′ untranslated regions, variations in DNA methylation, immediate early genes and transcription factors that regulate subunit expression, translational and post-translational modifications, and other forms of receptor regulation beyond expression. Advancing our understanding of the factors regulating GABA_AR subunit expression during adaptive plasticity, as well as during substance use and withdrawal will provide insight into the role of GABAergic signaling in substance use disorders, and contribute to the development of novel targeted therapies.

Alcohol associated liver disease 2020: A clinical practice guideline by the Italian Association for the Study of the Liver (AISF)

Alcohol use disorder which includes alcohol abuse and dependence represents one of the leading risk factors for premature mortality in Europe and it is responsible of over 200 conditions, including neuropsychiatric disorders, chronic diseases, cancers and accidents leading to permanent disability. Alcohol use disorder represents the most common cause of liver damage in the Western world, with a wide spectrum of diseases ranging from steatosis, steatohepatitis, fibrosis, cirrhosis and cancer. The present clinical practice guidelines by the Italian Association for the Study of the Liver (AISF) are focused on the current knowledge about epidemiology, pathophysiology, clinical features, diagnosis and treatment of alcohol associated liver disease, aiming to provide practical recommendations on the management of this complex pathological condition.