Identification of Circulating miRNAs Differentially Regulated by Opioid Treatment

Neuroplasticity-related genes correlate with individual differences in distinct phases of oxycodone self-administration in male rats

Opioid use disorder (OUD) is a chronic condition associated with long-lasting molecular and behavioral changes. Animals with prolonged access to opioids develop behaviors similar to human OUD. Identifying associated molecular changes can provide insight to underpinnings that lead to or maintain OUD. In pilot studies, we identified several miRNA targets that are altered by the administration of oxycodone. We selected mir182 for follow up as it was recently shown to be dysregulated in plasma of men administered oxycodone. In addition, mir182 is increased in reward-related brain regions of male rats following exposure to various addictive substances. The present study utilizes a long-access oxycodone self-administration paradigm to examine changes in mir182 and its mRNA targets associated with neuroplasticity, which may be involved in the maintenance of OUD-like phenotype in rats. Male rats were trained to self-administer oxycodone (0.1 mg/kg/infusion, i. v.) for 6 h daily sessions for 12 days. Each animal had a yoked saline control that received matched saline infusions. Animals were then tested on a progressive ratio schedule to measure motivation to obtain a single infusion of oxycodone. Drug seeking was measured following 28 days of forced abstinence using a 90-min cued/test. RTqPCR was utilized to measure mir182 and mRNA targets related to neuroplasticity (wnt3, plppr4, pou3f3, tle4, cacna2d, and bdnf) from the nucleus accumbens. Data revealed that animals responded on a continuum for oxycodone. When divided into two groups termed high- and low responders, animals diverged during self-administration acquisition and maintained differences in behavior and gene expression throughout the study. mir182 was upregulated in the nucleus accumbens of both high and low responders and negatively correlated with tle4, which showed a strong negative correlation with reinstatement behavior. mRNA target levels were correlated with behaviors associated with increased severity of OUD behavior in male rats.

A Pharmacogenomics-Based In Silico Investigation of Opioid Prescribing in Post-operative Spine Pain Management and Personalized Therapy

Considering the variability in individual responses to opioids and the growing concerns about opioid addiction, prescribing opioids for postoperative pain management after spine surgery presents significant challenges. Therefore, this study undertook a novel pharmacogenomics-based in silico investigation of FDA-approved opioid medications. The DrugBank database was employed to identify all FDA-approved opioids. Subsequently, the PharmGKB database was utilized to filter through all variant annotations associated with the relevant genes. In addition, the dpSNP ( https://www.ncbi.nlm.nih.gov/snp/ ), a publicly accessible repository, was used. Additional analyses were conducted using STRING-MODEL (version 12), Cytoscape (version 3.10.1), miRTargetLink.2, and NetworkAnalyst (version 3). The study identified 125 target genes of FDA-approved opioids, encompassing 7019 variant annotations. Of these, 3088 annotations were significant and pertained to 78 genes. During variant annotation assessments (VAA), 672 variants remained after filtration. Further in-depth filtration based on variant functions yielded 302 final filtered variants across 56 genes. The Monoamine GPCRs pathway emerged as the most significant signaling pathway. Protein-protein interaction (PPI) analysis revealed a fully connected network comprising 55 genes. Gene-miRNA Interaction (GMI) analysis of these 55 candidate genes identified miR-16-5p as a pivotal miRNA in this network. Protein-Drug Interaction (PDI) assessment showed that multiple drugs, including Ibuprofen, Nicotine, Tramadol, Haloperidol, Ketamine, L-Glutamic Acid, Caffeine, Citalopram, and Naloxone, had more than one interaction. Furthermore, Protein-Chemical Interaction (PCI) analysis highlighted that ABCB1, BCL2, CYP1A2, KCNH2, PTGS2, and DRD2 were key targets of the proposed chemicals. Notably, 10 chemicals, including carbamylhydrazine, tetrahydropalmatine, Terazosin, beta-methylcholine, rubimaillin, and quinelorane, demonstrated dual interactions with the aforementioned target genes. This comprehensive review offers multiple strong, evidence-based in silico findings regarding opioid prescribing in spine pain management, introducing 55 potential genes. The insights from this report can be applied in exome analysis as a pharmacogenomics (PGx) panel for pain susceptibility, facilitating individualized opioid prescribing through genotyping of related variants. The article also points out that African Americans represent an important group that displays a high catabolism of opioids and suggest the need for a personalized therapeutic approach based on genetic information.

Pharmacogenetic landscape of pain management variants among Mediterranean populations

Background

Chronic pain is a major socioeconomic burden in the Mediterranean region. However, we noticed an under-representation of these populations in the pharmacogenetics of pain management studies. In this context, we aimed 1) to decipher the pharmacogenetic variant landscape among Mediterranean populations compared to worldwide populations in order to identify therapeutic biomarkers for personalized pain management and 2) to better understand the biological process of pain management through in silico investigation of pharmacogenes pathways.

Materials and Methods

We collected genes and variants implicated in pain response using the Prisma guidelines from literature and PharmGK database. Next, we extracted these genes from genotyping data of 829 individuals. Then, we determined the variant distribution among the studied populations using multivariate (MDS) and admixture analysis with R and STRUCTURE software. We conducted a Chi2 test to compare the interethnic frequencies of the identified variants. We used SNPinfo web server, miRdSNP database to identify miRNA-binding sites. In addition, we investigated the functions of the identified genes and variants using pathway enrichment analysis and annotation tools. Finally, we performed docking analysis to assess the impact of variations on drug interactions.

Results

We identified 63 variants implicated in pain management. MDS analysis revealed that Mediterranean populations are genetically similar to Mexican populations and divergent from other populations. STRUCTURE analysis showed that Mediterranean populations are mainly composed of European ancestry. We highlighted differences in the minor allele frequencies of three variants (rs633, rs4680, and rs165728) located in the COMT gene. Moreover, variant annotation revealed ten variants with potential miRNA-binding sites. Finally, protein structure and docking analysis revealed that two missense variants (rs4680 and rs6267) induced a decrease in COMT protein activity and affinity for dopamine.

Conclusion

Our findings revealed that Mediterranean populations diverge from other ethnic groups. Furthermore, we emphasize the importance of pain-related pathways and miRNAs to better implement these markers as predictors of analgesic responses in the Mediterranean region.

Emergence of Extracellular Vesicles as "Liquid Biopsy" for Neurological Disorders: Boom or Bust

Extracellular vesicles (EVs) have emerged as an attractive liquid biopsy approach in the diagnosis and prognosis of multiple diseases and disorders. The feasibility of enriching specific subpopulations of EVs from biofluids based on their unique surface markers has opened novel opportunities to gain molecular insight from various tissues and organs, including the brain. Over the past decade, EVs in bodily fluids have been extensively studied for biomarkers associated with various neurological disorders, such as Alzheimer's disease, Parkinson's disease, schizophrenia, bipolar disorder, major depressive disorders, substance use disorders, human immunodeficiency virus-associated neurocognitive disorder, and cancer/treatment-induced neurodegeneration. These studies have focused on the isolation and cargo characterization of either total EVs or brain cells, such as neuron-, astrocyte-, microglia-, oligodendrocyte-, pericyte-, and endothelial-derived EVs from biofluids to achieve early diagnosis and molecular characterization and to predict the treatment and intervention outcomes. The findings of these studies have demonstrated that EVs could serve as a repetitive and less invasive source of valuable molecular information for these neurological disorders, supplementing existing costly neuroimaging techniques and relatively invasive measures, like lumbar puncture. However, the initial excitement surrounding blood-based biomarkers for brain-related diseases has been tempered by challenges, such as lack of central nervous system specificity in EV markers, lengthy protocols, and the absence of standardized procedures for biological sample collection, EV isolation, and characterization. Nevertheless, with rapid advancements in the EV field, supported by improved isolation methods and sensitive assays for cargo characterization, brain cell-derived EVs continue to offer unparallel opportunities with significant translational implications for various neurological disorders. SIGNIFICANCE STATEMENT: Extracellular vesicles present a less invasive liquid biopsy approach in the diagnosis and prognosis of various neurological disorders. Characterizing these vesicles in biofluids holds the potential to yield valuable molecular information, thereby significantly impacting the development of novel biomarkers for various neurological disorders. This paper has reviewed the methodology employed to isolate extracellular vesicles derived from various brain cells in biofluids, their utility in enhancing the molecular understanding of neurodegeneration, and the potential challenges in this research field.

Oxycodone, an opioid like the others?

The over-prescription of opioid analgesics is a growing problem in the field of addiction, which has reached epidemic-like proportions in North America. Over the past decade, oxycodone has gained attention as the leading opioid responsible for the North America opioid crisis. Oxycodone is the most incriminated drug in the early years of the epidemic of opioid use disorder in USA (roughly 1999-2016). The number of preclinical articles on oxycodone is rapidly increasing. Several publications have already compared oxycodone with other opioids, focusing mainly on their analgesic properties. The aim of this review is to focus on the genomic and epigenetic regulatory features of oxycodone compared with other opioid agonists. Our aim is to initiate a discussion of perceptible differences in the pharmacological response observed with these various opioids, particularly after repeated administration in preclinical models commonly used to study drug dependence potential.

Extracellular vesicles-Mediators of opioid use disorder?

Opioid use disorder (OUD) is a growing health emergency in the United States leading to an epidemic of overdose deaths. OUD is recognized as an addictive brain disorder resulting in psychological, cognitive and behavioural dysfunction. These observed clinical dysfunctions are a result of cellular changes that occur in the brain. Derangements in inflammation, neurogenesis and synaptic plasticity are observed in the brains of OUD patients. The mechanisms of these derangements are unclear; however, extracellular vesicles (EVs), membrane bound particles containing protein, nucleotides and lipids are currently being investigated as agents that invoke these cellular changes. The primary function of EVs is to facilitate intercellular communication by transfer of cargo (protein, nucleotides and lipids) between cells; however, changes in this cargo have been observed in models of OUD suggesting that EVs may be agents promoting the observed cellular derangements. This review summarizes evidence that altered cargo of EVs, specifically protein and miRNA, in models of OUD promote impairments in neurons, astrocytes and microglial cells. These findings support the premise that opioids alter EVs to detrimentally affect neuro-cellular function resulting in the observed addictive, psychological and neurocognitive deficits in OUD patients.

Clinical and biological significance of circulating miRNAs in chronic pancreatitis patients undergoing total pancreatectomy with islet autotransplantation

BACKGROUND

Specific microRNAs (miRNAs) were elevated in chronic pancreatitis (CP) patients during islet infusion after total pancreatectomy (TPIAT). We aimed to identify circulating miRNA signatures of pancreatic damage, predict miRNA-mRNA networks to identify potential links to CP pathogenesis and identify islet isolation and transplantation functional outcomes.

METHODS

Small RNA sequencing was performed to identify distinct circulating miRNA signatures in CP. Plasma miRNAs were measured using miRCURY LNA SYBR green quantitative real-time polymerase chain reaction assays. Correlation analyses were performed using R software. The miRNA target and disease interactions were determined using miRNet and the miRNA enrichment and annotation tool.

RESULTS

Alterations were found in circulating miRNAs in CP patients compared to healthy controls. Further studies were conducted on 12 circulating miRNAs enriched in the pancreas, other tissues and other diseases including cancer and fibrosis. Approximately 2888 mRNAs in the pancreas were their targets, demonstrating interactions with 76 small molecules. Three miRNAs exhibited interactions with morphine and five exhibited interactions with glucose. The miRNA panel targeted 22 genes associated with pancreatitis. The islet-specific, acinar cell-specific and liver-specific miRNAs were elevated at 6 h after islet infusion and returned to baseline levels 3 months after TPIAT. Circulating levels of miRNAs returned to pre-transplant levels 1-year post-transplant. Circulating miRNAs measured before and 6 h after islet infusion were directly or inversely associated with metabolic outcomes at 3 and 6 months post-transplant.

CONCLUSIONS

miRNAs may contribute to CP pathogenesis, and elevated circulating levels may be specific to pancreatic inflammation and fibrosis, warranting further investigation.

MicroRNA-mediated translational pathways are regulated in the orbitofrontal cortex and peripheral blood samples during acute abstinence from heroin self-administration

Opioid misuse in the United States contributes to >70% of annual overdose deaths. To develop additional therapeutics that may prevent opioid misuse, further studies on the neurobiological consequences of opioid exposure are needed. Here we sought to characterize molecular neuroadaptations involving microRNA (miRNA) pathways in the brain and blood of adult male rats that self-administered the opioid heroin. miRNAs are ∼18-24 nucleotide RNAs that regulate protein expression by preventing mRNA translation into proteins. Manipulation of miRNAs and their downstream pathways can critically regulate drug seeking behavior. We performed small-RNA sequencing of miRNAs and proteomics profiling on tissue from the orbitofrontal cortex (OFC), a brain region associated with heroin seeking, following 2 days of forced abstinence from self-administration of 0.03 mg/kg/infusion heroin or sucrose. Heroin self-administration resulted in a robust shift of the OFC miRNA profile, regulating 77 miRNAs, while sucrose self-administration only regulated 9 miRNAs that did not overlap with the heroin-induced profile. Conversely, proteomics revealed dual regulation of seven proteins by both heroin and sucrose in the OFC. Pathway analysis determined that heroin-associated miRNA pathways are predicted to target genes associated with the term "prion disease," a term that was also enriched in the heroin-induced protein expression dataset. Lastly, we confirmed that a subset of heroin-induced miRNA expression changes in the OFC are regulated in peripheral serum and correlate with heroin infusions. These findings demonstrate that peripheral blood samples may have biomarker utility for assessment of drug-induced miRNA pathway alterations that occur in the brain following chronic drug exposure.

Epigenetic regulation in opioid induced hyperalgesia

About 25 million American adults experience pain daily and one of the most commonly prescribed drugs to treat pain are opioids. Prolonged opioid usage and dose escalations can cause a paradoxical response where patients experience enhanced pain sensitivity. This opioid induced hyperalgesia (OIH) is a major hurdle when treating pain in the clinic because its underlying mechanisms are still not fully understood. OIH is also commonly overlooked and lacks guidelines to prevent its onset. Research on pain disorders and opioid usage have recognized potential epigenetic drivers of disease including DNA methylation, histone modifications, miRNA regulation, but their involvement in OIH has not been well studied. This article discusses epigenetic changes that may contribute to pathogenesis, with an emphasis on miRNA alterations in OIH. There is a crucial gap in knowledge including how multiple epigenetic modulators contribute to OIH. Elucidating the epigenetic changes underlying OIH and the crosstalk among these mechanisms could lead to the development of novel targets for the prevention and treatment of this painful phenomena.

Repeated Use of Morphine Induces Anxiety by Affecting a Proinflammatory Cytokine Signaling Pathway in the Prefrontal Cortex in Rats

We examined the role of toll-like receptors (TLRs) and proinflammatory cytokine signaling pathways in the prefrontal cortex (PFC) in anxiety-like behaviors after repeated use of morphine. Morphine (10 mg/kg) was used twice daily for 8 days to induce morphine dependence in male Wistar rats. On day 8, opioid dependence was confirmed by measuring naloxone-precipitated withdrawal signs. On days 1 and 8, anxiety-like behaviors were evaluated using a light/dark box test. Expression of TLR1 and 4, proinflammatory cytokines, and some of the downstream signaling molecules was also evaluated in the bilateral PFC at mRNA and protein levels following morphine dependence. The results revealed that morphine caused anxiolytic-like effects on day 1 while induced anxiety following 8 days of repeated injection. On day 8, a significant decrease in TLR1 expression was detected in the PFC in morphine-dependent rats, but TLR4 remained unaffected. Repeated morphine injection significantly increased IL1-β, TNFα, and IL6 expression, but decreased IL1R and TNFR at mRNA and protein levels except for IL6R at the protein level in the PFC. The p38α mitogen-activated protein (MAP) kinase expression significantly increased but the JNK3 expression decreased in the PFC in morphine-dependent rats. Repeated injection of morphine also significantly increased the NF-κB expression in the PFC. Further, significant increases in Let-7c, mir-133b, and mir-365 were detected in the PFC in morphine-dependent rats. We conclude that TLR1 and proinflammatory cytokines signaling pathways in the PFC are associated with the anxiogenic-like effects of morphine following its chronic use in rats via a MAP kinase/NF-κB pathway.

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.

Morphine-mediated release of astrocyte-derived extracellular vesicle miR-23a induces loss of pericyte coverage at the blood-brain barrier: Implications for neuroinflammation

Opioids such as morphine are the most potent and efficacious drugs currently available for pain management. Paradoxically, opioids have also been implicated in inducing neuroinflammation and associated neurocognitive decline. Pericytes, a critical component of the neurovascular unit (NVU), are centrally positioned between endothelial cells and astrocytes, maintaining function of the blood-brain barrier (BBB) nd regulating neuroinflammation by controlling monocyte influx under various pathological conditions. The role of pericytes in morphine-mediated neuroinflammation however, has received less attention, especially in the context of how pericytes crosstalk with other central nervous system (CNS) cells. The current study was undertaken to examine the effect of miRNAs released from morphine-stimulated human primary astrocyte-derived extracellular vesicles (morphine-ADEVs) in mediating pericyte loss at the blood-brain barrier, leading, in turn, to increased influx of peripheral monocytes. Our findings suggest that the heterogeneous nuclear ribonucleoprotein complex A2/B1 (hnRNP A2/B1) plays role in morphine-mediated upregulation and release of miR-23a in ADEVs, and through action of morphine via mu opioid receptor.We further demonstrated that miR-23a in morphine-ADEVs could be taken up by pericytes, resulting in downregulation of PTEN expression, ultimately leading to increased pericyte migration. Furthermore, both overexpression of PTEN and blocking the miR-23a target site at PTEN 3UTR (by transfecting miR-23a-PTEN target protector), attenuated morphine-ADEV-mediated pericyte migration. We also demonstrated that in the microvessels isolated from morphine-administered mice, there were fewer PDGFβR + pericytes co-localizing with CD31+ brain endothelial cells compared with those from saline mice. In line with these findings, we also observed increased loss of pericytes and a concomitantly increased influx of monocytes in the brains of morphine-administered pericyte-labeled NG2-DsRed mice compared with saline mice. In conclusion, our findings indicate morphine-ADEVs mediated loss of pericyte coverage at the brain endothelium, thereby increasing the influx of peripheral monocytes in the central nervous system, leading to neuroinflammation.

Sustained Morphine Delivery Suppresses Bone Formation and Alters Metabolic and Circulating miRNA Profiles in Male C57BL/6J Mice

Opioid use is detrimental to bone health, causing both indirect and direct effects on bone turnover. Although the mechanisms of these effects are not entirely clear, recent studies have linked chronic opioid use to alterations in circulating miRNAs. Here, we developed a model of opioid-induced bone loss to understand bone turnover and identify candidate miRNA-mediated regulatory mechanisms. We evaluated the effects of sustained morphine treatment on male and female C57BL/6J mice by treating with vehicle (0.9% saline) or morphine (17 mg/kg) using subcutaneous osmotic minipumps for 25 days. Morphine-treated mice had higher energy expenditure and respiratory quotient, indicating a shift toward carbohydrate metabolism. Micro-computed tomography (μCT) analysis indicated a sex difference in the bone outcome, where male mice treated with morphine had reduced trabecular bone volume fraction (Tb.BV/TV) (15%) and trabecular bone mineral density (BMD) (14%) in the distal femur compared with vehicle. Conversely, bone microarchitecture was not changed in females after morphine treatment. Histomorphometric analysis demonstrated that in males, morphine reduced bone formation rate compared with vehicle, but osteoclast parameters were not different. Furthermore, morphine reduced bone formation marker gene expression in the tibia of males (Bglap and Dmp1). Circulating miRNA profile changes were evident in males, with 14 differentially expressed miRNAs associated with morphine treatment compared with two differentially expressed miRNAs in females. In males, target analysis indicated hypoxia-inducible factor (HIF) signaling pathway was targeted by miR-223-3p and fatty acid metabolism by miR-484, -223-3p, and -328-3p. Consequently, expression of miR-223-3p targets, including Igf1r and Stat3, was lower in morphine-treated bone. In summary, we have established a model where morphine leads to a lower trabecular bone formation in males and identified potential mediating miRNAs. Understanding the sex-specific mechanisms of bone loss from opioids will be important for improving management of the adverse effects of opioids on the skeleton. © 2022 American Society for Bone and Mineral Research (ASBMR).

Digital Analgesic Comprising a Second-Generation Digital Health System: Increasing Effectiveness by Optimizing the Dosing and Minimizing Side Effects

Opioids remain an essential part of the treatment of chronic pain. However, their use and increasing rates of misuse are associated with high morbidity and mortality. The development of tolerance to opioids and analgesics further complicates dosing and the need to reduce side effects. First-generation digital systems were developed to improve analgesics but are not always capable of making clinically relevant associations and do not necessarily lead to better clinical efficacy. A lack of improved clinical outcomes makes these systems less applicable for adoption by clinicians and patients. There is a need to enhance the therapeutic regimens of opioids. In the present paper, we present the use of a digital analgesic that consists of an analgesic administered under the control of a second-generation artificial intelligence system. Second-generation systems focus on improved patient outcomes measured based on clinical response and reduced side effects in a single subject. The algorithm regulates the administration of analgesics in a personalized manner. The digital analgesic provides advantages for both users and providers. The system enables dose optimization, improving effectiveness, and minimizing side effects while increasing adherence to beneficial therapeutic regimens. The algorithm improves the clinicians’ experience and assists them in managing chronic pain. The system reduces the financial burden on healthcare providers by lowering opioid-related morbidity and provides a market disruptor for pharma companies.

Prenatal opioid-exposed infant extracellular miRNA signature obtained at birth predicts severity of neonatal opioid withdrawal syndrome

Prenatal opioid exposure (POE) is commonly associated with neonatal opioid withdrawal syndrome (NOWS), which is characterized by a broad variability in symptoms and severity. Currently there are no diagnostic tools to reliably predict which infants will develop severe NOWS, while risk stratification would allow for proactive decisions about appropriate clinical monitoring and interventions. The aim of this prospective cohort study was to assess if extracellular microRNAs (miRNAs) in umbilical cord plasma of infants with POE could predict NOWS severity. Participants (n = 58) consisted of pregnant women receiving medications for opioid use disorder and their infants. NOWS severity was operationalized as the need for pharmacologic treatment and prolonged hospitalization (≥ 14 days). Cord blood miRNAs were assessed using semi-quantitative qRT-PCR arrays. Receiver operating characteristic curves and area under the curve (AUC) were estimated. The expression of three miRNAs (miR-128-3p, miR-30c-5p, miR-421) predicted need for pharmacologic treatment (AUC: 0.85) and prolonged hospitalization (AUC: 0.90). Predictive validity improved after two miRNAs (let-7d-5p, miR-584-5p) were added to the need for pharmacologic treatment model (AUC: 0.94) and another two miRNAs (let-7b-5p, miR-10-5p) to the prolonged hospitalization model (AUC: 0.99). Infant cord blood extracellular miRNAs can proactively identify opioid-exposed neonates at high-risk for developing severe NOWS.

microRNA expression levels in the nucleus accumbens correlate with morphine-taking but not morphine-seeking behaviour in male rats

A powerful motivation to seek opioids remains after drug cessation and intensifies during extended periods of abstinence. Unfortunately, biomarkers associated with continued drug seeking have not been described. Moreover, previous studies have focused on the effects of early abstinence with little exploration into the long-term drug-induced mechanisms that occur after extended abstinence. Here we demonstrated that 30 days (D) of forced abstinence results in a time-dependent increase in morphine seeking in a rat model of morphine self-administration (SA). We measured expression of known drug-responsive microRNAs (miRNAs) in the nucleus accumbens, an area critical for reward-related plasticity, during early or late abstinence in animals that underwent either a cue-induced relapse test or no relapse test. miRNAs are small noncoding RNAs that represent suitable biomarker candidates due to their long-lasting nature. mir-32-5p levels during early abstinence negatively correlated with active lever pressing in both cue-exposed and cue-naïve animals. mir-1298-5p positively correlated with drug SA history after a relapse test during late abstinence. When animals underwent acute abstinence with no relapse test, mir-1298-5p correlated with drug infusions and active lever pressing during SA. In late abstinence with no relapse test, mir-137-3p negatively correlated with drug infusions. Regulation of mir-32-5p target genes and significant correlation of target gene mRNA with mir-32-5p was observed after abstinence. These results indicate that lasting regulation of miRNA expression is associated with drug intake following morphine SA. In addition, we conclude that the miRNA profile undergoes regulation from early to late abstinence and miRNA expression may indicate past drug history.

Blood-Based miRNA Biomarkers as Correlates of Brain-Based miRNA Expression

The use of easily accessible peripheral samples, such as blood or saliva, to investigate neurological and neuropsychiatric disorders is well-established in genetic and epigenetic research, but the pathological implications of such biomarkers are not easily discerned. To better understand the relationship between peripheral blood- and brain-based epigenetic activity, we conducted a pilot study on captive baboons (Papio hamadryas) to investigate correlations between miRNA expression in peripheral blood mononuclear cells (PBMCs) and 14 different cortical and subcortical brain regions, represented by two study groups comprised of 4 and 6 animals. Using next-generation sequencing, we identified 362 miRNAs expressed at ≥ 10 read counts in 80% or more of the brain samples analyzed. Nominally significant pairwise correlations (one-sided P < 0.05) between peripheral blood and mean brain expression levels of individual miRNAs were observed for 39 and 44 miRNAs in each group. When miRNA expression levels were averaged for tissue type across animals within the groups, Spearman's rank correlations between PBMCs and the brain regions are all highly significant (r _s = 0.47-0.57; P < 2.2 × 10^-16), although pairwise correlations among the brain regions are markedly stronger (r _s = 0.86-0.99). Principal component analysis revealed differentiation in miRNA expression between peripheral blood and the brain regions for the first component (accounting for ∼75% of variance). Linear mixed effects modeling attributed most of the variance in expression to differences between miRNAs (>70%), with non-significant 7.5% and 13.1% assigned to differences between blood and brain-based samples in the two study groups. Hierarchical UPGMA clustering revealed a major co-expression branch in both study groups, comprised of miRNAs globally upregulated in blood relative to the brain samples, exhibiting an enrichment of miRNAs expressed in immune cells (CD14+, CD15+, CD19+, CD3+, and CD56 + leukocytes) among the top blood-brain correlates, with the gene MYC, encoding a master transcription factor that regulates angiogenesis and neural stem cell activation, representing the most prevalent miRNA target. Although some differentiation was observed between tissue types, these preliminary findings reveal wider correlated patterns between blood- and brain-expressed miRNAs, suggesting the potential utility of blood-based miRNA profiling for investigating by proxy certain miRNA activity in the brain, with implications for neuroinflammatory and c-Myc-mediated processes.

Opioids and Sepsis: Elucidating the Role of the Microbiome and microRNA-146

Sepsis has recently been defined as life-threatening organ dysfunction caused by the dysregulated host response to an ongoing or suspected infection. To date, sepsis continues to be a leading cause of morbidity and mortality amongst hospitalized patients. Many risk factors contribute to development of sepsis, including pain-relieving drugs like opioids, which are frequently prescribed post-operatively. In light of the opioid crisis, understanding the interactions between opioid use and the development of sepsis has become extremely relevant, as opioid use is associated with increased risk of infection. Given that the intestinal tract is a major site of origin of sepsis-causing microbes, there has been an increasing focus on how alterations in the gut microbiome may predispose towards sepsis and mediate immune dysregulation. MicroRNAs, in particular, have emerged as key modulators of the inflammatory response during sepsis by tempering the immune response, thereby mediating the interaction between host and microbiome. In this review, we elucidate contributing roles of microRNA 146 in modulating sepsis pathogenesis and end with a discussion of therapeutic targeting of the gut microbiome in controlling immune dysregulation in sepsis.

MicroRNA-mRNA networks are dysregulated in opioid use disorder postmortem brain: Further evidence for opioid-induced neurovascular alterations

INTRODUCTION

To understand mechanisms and identify potential targets for intervention in the current crisis of opioid use disorder (OUD), postmortem brains represent an under-utilized resource. To refine previously reported gene signatures of neurobiological alterations in OUD from the dorsolateral prefrontal cortex (Brodmann Area 9, BA9), we explored the role of microRNAs (miRNA) as powerful epigenetic regulators of gene function.

METHODS

Building on the growing appreciation that miRNAs can cross the blood-brain barrier, we carried out miRNA profiling in same-subject postmortem samples from BA9 and blood tissues.

RESULTS

miRNA-mRNA network analysis showed that even though miRNAs identified in BA9 and blood were fairly distinct, their target genes and corresponding enriched pathways overlapped strongly. Among the dominant enriched biological processes were tissue development and morphogenesis, and MAPK signaling pathways. These findings point to robust, redundant, and systemic opioid-induced miRNA dysregulation with a potential functional impact on transcriptomic changes. Further, using correlation network analysis, we identified cell-type specific miRNA targets, specifically in astrocytes, neurons, and endothelial cells, associated with OUD transcriptomic dysregulation. Finally, leveraging a collection of control brain transcriptomes from the Genotype-Tissue Expression (GTEx) project, we identified a correlation of OUD miRNA targets with TGF beta, hypoxia, angiogenesis, coagulation, immune system, and inflammatory pathways.

DISCUSSION

These findings support previous reports of neurovascular and immune system alterations as a consequence of opioid abuse and shed new light on miRNA network regulators of cellular response to opioid drugs.

The Clinical Significance and Immunization of MSMO1 in Cervical Squamous Cell Carcinoma Based on Bioinformatics Analysis

Objective: The genetic markers for the detection or treatment of cervical squamous cell carcinoma (CESC) are not yet complete. This study aimed to identify the role of MSMO1 (Alternative name: SC4MOL) in the occurrence and development of CESC. Methods: We evaluated the significance of MSMO1 expression in CESC by using analysis of a public dataset from the Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO) database. Oncomine and GEPIA2 were used to validate MSMO1 as an independent prognostic factor in CESC. Multiple tools were used to analyze the factors and functions associated with MSMO1, such as methylation, miRNA, and co-expressed genes. Furthermore, TIMER and TISIDB were used to study the relationship between MSMO1 expression and immunization in CESC. Results: MSMO1 was highly expressed in tumor specimens and could be used as an independent prognostic factor of CESC (p < 0.05). But Casiopeinas chemotherapeutics and p63 loss could reduce the expression of MSMO1. The level of methylation MSMO1 was significantly increased in tumor tissues but there was an insignificant effect on the prognosis. MSMO1 was also closely related to hsa-miR-23a-3p, hsa-miR-23b-3p, hsa-miR-130b-3p, and gene IDI1. Specifically, the expression level of MSMO1 had a significant negative correlation with the infiltration level of CD4+T cells, Macrophages, Neutrophils, and DCs in CESC. In addition, GSEA identified differential enrichment in systemic lupus erythematosus, vascular smooth muscle contraction, cytokine receptor interaction, focal adhesion, chemokine signaling pathway, and Leishmania infection pathway in KEGG. Conclusion: Our findings provide evidence of the implications of MSMO1 in tumors, suggesting that MSMO1 is a promising prognostic biomarker in CESC.

Recent advances in dielectrophoresis toward biomarker detection: A summary of studies published between 2014 and 2021

Dielectrophoresis is a well-understood phenomenon that has been widely utilized in biomedical applications. Recent advancements in miniaturization have contributed to the development of dielectrophoretic-based devices for a wide variety of biomedical applications. In particular, the integration of dielectrophoresis with microfluidics, fluorescence, and electrical impedance has produced devices and techniques that are attractive for screening and diagnosing diseases. This review article summarizes the recent utility of dielectrophoresis in assays of biomarker detection. Common screening and diagnostic biomarkers, such as cellular, protein, and nucleic acid, are discussed. Finally, the potential use of recent developments in machine learning approaches toward improving biomarker detection performance is discussed. This review article will be useful for researchers interested in the recent utility of dielectrophoresis in the detection of biomarkers and for those developing new devices to address current gaps in dielectrophoretic biomarker detection.

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.

The Life Cycle of the Mu-Opioid Receptor

Opioid receptors (ORs) are undisputed targets for the treatment of pain. Unfortunately, targeting these receptors therapeutically poses significant challenges including addiction, dependence, tolerance, and the appearance of side effects, such as respiratory depression and constipation. Moreover, misuse of prescription and illicit narcotics has resulted in the current opioid crisis. The mu-opioid receptor (MOR) is the cellular mediator of the effects of most commonly used opioids, and is a prototypical G protein-coupled receptor (GPCR) where new pharmacological, signalling and cell biology concepts have been coined. This review summarises the knowledge of the life cycle of this therapeutic target, including its biogenesis, trafficking to and from the plasma membrane, and how the regulation of these processes impacts its function and is related to pathophysiological conditions.

Brain cell-derived exosomes in plasma serve as neurodegeneration biomarkers in male cynomolgus monkeys self-administrating oxycodone

Background

The United States is currently facing an opioid crisis. Novel tools to better comprehend dynamic molecular changes in the brain associated with the opioid abuse are limited. Recent studies have suggested the usefulness of plasma exosomes in better understanding CNS disorders. However, no study has ever characterized exosomes (small extracellular vesicles of endocytic origin) secreted by brain cells to understand the potential neurodegenerative effects of long-term oxycodone self-administration (SA).

Methods

MRI of Cynomolgus monkeys (Macaca fascicularis) was performed to assess alterations in gray matter volumes with oxycodone SA. We isolated total exosomes (TE) from the plasma of these monkeys; from TE, we pulled-out neuron-derived exosomes (NDE), astrocytes-derived exosomes (ADE), and microglia-derived exosomes (MDE) using surface biomarkers L1CAM (L1 cell adhesion molecule), GLAST (Glutamate aspartate transporter) and TMEM119 (transmembrane protein119), respectively.

Findings

We observed a significantly lower gray matter volume of specific lobes of the brain (frontal and parietal lobes, and right putamen) in monkeys with ∼3 years of oxycodone SA compared to controls. Higher expression of neurodegenerative biomarkers (NFL and α-synuclein) correlates well with the change in brain lobe volumes in control and oxycodone SA monkeys. We also identified a strong effect of oxycodone SA on the loading of specific miRNAs and proteins associated with neuro-cognitive disorders. Finally, exosomes subpopulation from oxycodone SA group activated NF-κB activity in THP1- cells.

Interpretation

These results provide evidence for the utility of brain cells-derived exosomes from plasma in better understanding and predicting the pro-inflammatory and neurodegenerative consequence of oxycodone SA.

Funding

NIH

Gut-Amygdala Interactions in Autism Spectrum Disorders: Developmental Roles via regulating Mitochondria, Exosomes, Immunity and microRNAs

BACKGROUND

Autism Spectrum Disorders (ASD) have long been conceived as developmental disorder. A growing body of data highlights a role for alterations in the gut in the pathoetiology and/or pathophysiology of ASD. Recent work shows alterations in the gut microbiome to have a significant impact on amygdala development in infancy, suggesting that the alterations in the gut microbiome may act to modulate not only amygdala development but how the amygdala modulates the development of the frontal cortex and other brain regions.

METHODS

This article reviews wide bodies of data pertaining to the developmental roles of the maternal and foetal gut and immune systems in the regulation of offspring brain development.

RESULTS

A number of processes seem to be important in mediating how genetic, epigenetic and environmental factors interact in early development to regulate such gut-mediated changes in the amygdala, wider brain functioning and inter-area connectivity, including via regulation of microRNA (miR)-451, 14-3-3 proteins, cytochrome P450 (CYP)1B1 and the melatonergic pathways. As well as a decrease in the activity of monoamine oxidase, heightened levels of in miR-451 and CYP1B1, coupled to decreased 14-3-3 act to inhibit the synthesis of N-acetylserotonin and melatonin, contributing to the hyperserotonemia that is often evident in ASD, with consequences for mitochondria functioning and the content of released exosomes. These same factors are likely to play a role in regulating placental changes that underpin the association of ASD with preeclampsia and other perinatal risk factors, including exposure to heavy metals and air pollutants. Such alterations in placental and gut processes act to change the amygdala-driven biological underpinnings of affect-cognitive and affect-sensory interactions in the brain.

CONCLUSION

Such a perspective readily incorporates previously disparate bodies of data in ASD, including the role of the mu-opioid receptor, dopamine signaling and dopamine receptors, as well as the changes occurring to oxytocin and taurine levels. This has a number of treatment implications, the most readily applicable being the utilization of sodium butyrate and melatonin.

Integrating Pathophysiology in Migraine: Role of the Gut Microbiome and Melatonin

BACKGROUND

The pathoetiology and pathophysiology of migraine are widely accepted as unknown.

METHODS

The current article reviews the wide array of data associated with the biological underpinnings of migraine and provides a framework that integrates previously disparate bodies of data.

RESULTS

The importance of alterations in stress- and pro-inflammatory cytokine- induced gut dysbiosis, especially butyrate production, are highlighted. This is linked to a decrease in the availability of melatonin, and a relative increase in the N-acetylserotonin/melatonin ratio, which has consequences for the heightened glutamatergic excitatory transmission in migraine. It is proposed that suboptimal mitochondria functioning and metabolic regulation drive alterations in astrocytes and satellite glial cells that underpin the vasoregulatory and nociceptive changes in migraine.

CONCLUSION

This provides a framework not only for classical migraine associated factors, such as calcitonin-gene related peptide and serotonin, but also for wider factors in the developmental pathoetiology of migraine. A number of future research and treatment implications arise, including the clinical utilization of sodium butyrate and melatonin in the management of migraine.

Endogenous opiates and behavior: 2017

This paper is the fortieth consecutive installment of the annual anthological review of research concerning the endogenous opioid system, summarizing articles published during 2017 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides and receptors as well as effects of opioid/opiate agonists and antagonists. The review is subdivided into the following specific topics: molecular-biochemical effects and neurochemical localization studies of endogenous opioids and their receptors (1), the roles of these opioid peptides and receptors in pain and analgesia in animals (2) and humans (3), opioid-sensitive and opioid-insensitive effects of nonopioid analgesics (4), opioid peptide and receptor involvement in tolerance and dependence (5), stress and social status (6), learning and memory (7), eating and drinking (8), drug abuse and alcohol (9), sexual activity and hormones, pregnancy, development and endocrinology (10), mental illness and mood (11), seizures and neurologic disorders (12), electrical-related activity and neurophysiology (13), general activity and locomotion (14), gastrointestinal, renal and hepatic functions (15), cardiovascular responses (16), respiration and thermoregulation (17), and immunological responses (18).

Opioid-induced immunosuppression and carcinogenesis promotion theories create the newest trend in acute and chronic pain pharmacotherapy

Opioids are the main group of pharmacological agents used during the perioperative period and provide a sedative and analgesic component. The observations of opioid consumption in West Europe indicate that this group of drugs is widely used in chronic noncancer pain therapy. Nearly 20 years ago, the first publications indicating that opioids, as an element of perioperative pharmacotherapy in oncologic patients, increase the risk of tumor recurrence and affect further prognosis were presented. The actual publications suggest that there are multifactorial, complex mechanisms underlying the immunological impact and carcinogenesis promotion of opioids and that the intensity varies depending on the type of opioid. There are also questions about the immunosuppressive effects among patients receiving opioids in the treatment of chronic noncancer pain. The aim of the review article is to present information about the action of opioids on the immune system in carcinogenic settings and to define the clinical usefulness of this pharmacological phenomenon.

Epigenetic pharmacotherapy for substance use disorder

Identifying novel therapeutics for the treatment of substance use disorder (SUD) is an area of intensive investigation. Prior strategies that have attempted to modify one or a few neurotransmitter receptors have had limited success, and currently there are no FDA-approved medications for the treatment of cocaine, methamphetamine, and marijuana use disorders. Because drugs of abuse are known to alter the expression of numerous genes in reward-related brain regions, epigenetic-based therapies have emerged as intriguing targets for therapeutic innovation. Here, I evaluate potential therapeutic approaches and challenges in targeting epigenetic factors for the treatment of SUD and highlight examples of promising strategies and future directions.

Decreased Level of Blood MicroRNA-133b in Men with Opioid Use Disorder on Methadone Maintenance Therapy

Although previous animal studies have indicated that certain micro ribonucleic acids (microRNAs) play a part in the pathway of opioid addiction, whether such findings extend to human models is yet unknown. This study aims to investigate the important microRNA expressions in patients with opioid use disorder (OUD) on methadone maintenance treatment (MMT) compared to healthy controls and analyze the correlation between microRNAs and opioid characteristics among the patients. We recruited 50 patients and 25 controls, and both groups were matched regarding gender, age, and body mass index. Serum microRNAs (miR-133b, miR-23b, miR-190, miR-206, miR-210, and miR-21) were measured. The age of OUD onset, duration of MMT participation, and recent daily methadone dosage were considered the opioid characteristics. We adopted the t-test to compare the difference between patients and controls and Pearson's correlation to evaluate the association between microRNAs and opioid profiles. Only the level of miR-133b in OUD patients on MMT was significantly lower than that in healthy controls. We did not detect differences of any other microRNA expressions between the two groups. Furthermore, we found no evidence to support the association between microRNAs and opioid characteristics. This study indicates that miR-133b values may be decreased in OUD patients on MMT.

Differences in the miRNA signatures of chronic musculoskeletal pain patients from neuropathic or nociceptive origins

BACKGROUND

The quality of life for millions of people worldwide is affected by chronic pain. In addition to the effect of chronic pain on well-being, chronic pain has also been associated with poor health conditions and increased mortality. Due to its multifactorial origin, the classification of pain types remains challenging. MicroRNAs (miRNA) are small molecules that regulate gene expression. They are released into the bloodstream in a stable manner under normal and pathological conditions and have been described as potential biomarkers. In the present study, we aimed to investigate whether pain may induce an aberrant, specific dysregulation of miRNA expression, depending on the origin of the pain.

METHODS AND FINDINGS

To do so, we measured the expression changes of 184 circulating miRNAs (c-miRNAs) in the plasma samples of patients with different origins of chronic musculoskeletal pain. After statistical analyses, we identified seven c-miRNA candidates that were differentially expressed depending on the nociceptive or neuropathic origin of the pain. We then developed a two c-miRNA signature (hsa-miR-320a and hsa-miR-98-5p) that was able to correctly classify the pain type of 70% of the patients from the validation set.

CONCLUSIONS

In conclusion, circulating miRNAs are promising biomarkers to identify and characterize the chronic pain type and to further improve its clinical management.

The Emerging Perspective of Morphine Tolerance: MicroRNAs

Morphine has unfavorable side effects including analgesic tolerance. Morphine tolerance counteracts analgesic efficacy and drives dose escalation. The mechanisms underlying morphine tolerance remain disputed, which has prevented the development of therapies to maximize and sustain analgesic efficacy. Morphine tolerance is an adaptive process induced by chronic morphine that has been shown to result from complex alterations at the molecular level with μ opioid receptors (MORs), as well as at the synaptic, cellular, and circuit levels. MicroRNAs are noncoding RNAs that have been proposed to regulate gene expression and degradation at the posttranscriptional level, including the MOR, as well as synaptic plasticity and neuroplasticity, in both the peripheral and central nervous systems. This review covers some of the most striking microRNA functions involved in morphine tolerance and presents limitations on our knowledge of their physiological roles.

Imatinib-induced changes in the expression profile of microRNA in the plasma and heart of mice-A comparison with doxorubicin

Cardiotoxicity is a serious adverse reaction to cancer chemotherapy and may lead to critical heart damage. Imatinib mesylate (IMB), a selective tyrosine kinase inhibitor, is sometimes accompanied by severe cardiovascular complications. To minimize risk, early biomarkers of such complications are of utmost importance. At the present time, microRNAs (miRNAs) are intensively studied as potential biomarkers of many pathological processes. Many miRNAs appear to be specific in some tissues, including the heart. In the present study we have explored the potential of specific miRNAs to be early markers of IMB-induced cardiotoxicity. Doxorubicin (DOX), an anthracycline with well-known cardiotoxicity, was used for comparison. NMRI mice were treated with IMB or DOX for nine days in doses corresponding to the highest recommended doses in oncological patients, following which plasmatic levels of miRNAs were analyzed in miRNA microarrays and selected cardio-specific miRNAs were quantified using qPCR. The plasmatic level of miR-1a, miR-133a, miR-133b, miR-339, miR-7058, miR-6236 and miR-6240 were the most different between the IMB-treated and control mice. Interestingly, most of the miRNAs affected by DOX were also affected by IMB showing the same trends. Concerning selected microRNAs in the hearts of individual mice, only miR-34a was significantly increased after DOX treatment, and only miR-205 was significantly decreased after IMB and DOX treatment. However, no changes in any miRNA expression correlated with the level of troponin T, a classical marker of heart injury.

Circulating miRNA Signature as a Potential Biomarker for the Prediction of Analgesic Efficacy of Hydromorphone

No practical biomarkers currently exist for the prediction of the analgesic efficacy of opioids. Previously, we reported circulating miRNA signatures differentially regulated by µ-opioid receptor (MOR) agonists in healthy subjects. We hypothesized that these miRNAs could be potential pharmacodynamic biomarkers to estimate MOR stimulation, and predict the efficacy of opioids; i.e., patients with low MOR stimulation may be more vulnerable to strengthening of the MOR signal upon hydromorphone treatment. To test this hypothesis, plasma samples were obtained from 25 patients with cancer pain prior to the initiation of hydromorphone treatment and the circulating miRNA levels were evaluated, focusing on four miRNAs (i.e., hsa-miR-423-3p, hsa-let-7a-5p, hsa-miR-26a-5p, and hsa-let-7f-5p) and four miRNAs (i.e., hsa-miR-144-3p, hsa-miR-451a, hsa-miR-215, and hsa-miR-363-3p) that were most clearly up and downregulated by hydromorphone and oxycodone. The patients were classified into two classes with putative high and low MOR signal, estimated based on the plasma miRNA signature. A significant correlation was observed between the analgesic efficacy and the putative MOR signal level, and patients with low MOR signal achieved better pain control (i.e., ΔVAS < 0) through hydromorphone. These results suggested that plasma miRNA signatures could serve as clinical biomarkers for the prediction of the analgesic efficacy of hydromorphone.

Novel Roles of Non-Coding RNAs in Opioid Signaling and Cardioprotection

Cardiovascular disease (CVD) is a significant cause of morbidity and mortality across the world. A large proportion of CVD deaths are secondary to coronary artery disease (CAD) and myocardial infarction (MI). Even though prevention is the best strategy to reduce risk factors associated with MI, the use of cardioprotective interventions aimed at improving patient outcomes is of great interest. Opioid conditioning has been shown to be effective in reducing myocardial ischemia-reperfusion injury (IRI) and cardiomyocyte death. However, the molecular mechanisms behind these effects are under investigation and could provide the basis for the development of novel therapeutic approaches in the treatment of CVD. Non-coding RNAs (ncRNAs), which are functional RNA molecules that do not translate into proteins, are critical modulators of cardiac gene expression during heart development and disease. Moreover, ncRNAs such as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs) are known to be induced by opioid receptor activation and regulate opioid signaling pathways. Recent advances in experimental and computational tools have accelerated the discovery and functional characterization of ncRNAs. In this study, we review the current understanding of the role of ncRNAs in opioid signaling and opioid-induced cardioprotection.