Genome-Wide, Integrative Analysis Implicates Exosome-Derived MicroRNA Dysregulation in Schizophrenia

Comparison of Oncogenes, Tumor Suppressors, and MicroRNAs Between Schizophrenia and Glioma: The Balance of Power

The risk of cancer in schizophrenia has been controversial. Confounders of the issue are cigarette smoking in schizophrenia, and antiproliferative effects of antipsychotic medications. The author has previously suggested comparison of a specific cancer like glioma to schizophrenia might help determine a more accurate relationship between cancer and schizophrenia. To accomplish this goal, the author performed three comparisons of data; the first a comparison of conventional tumor suppressors and oncogenes between schizophrenia and cancer including glioma. This comparison determined schizophrenia has both tumor-suppressive and tumor-promoting characteristics. A second, larger comparison between brain-expressed microRNAs in schizophrenia with their expression in glioma was then performed. This identified a core carcinogenic group of miRNAs in schizophrenia offset by a larger group of tumor-suppressive miRNAs. This proposed "balance of power" between oncogenes and tumor suppressors could cause neuroinflammation. This was assessed by a third comparison between schizophrenia, glioma and inflammation in asbestos-related lung cancer and mesothelioma (ALRCM). This revealed that schizophrenia shares more oncogenic similarity to ALRCM than glioma.

Identification of serum exosomal metabolomic and proteomic profiles for remote ischemic preconditioning

BACKGROUND

Remote ischemic preconditioning (RIPC) refers to a brief episode of exposure to potential adverse stimulation and prevents injury during subsequent exposure. RIPC has been shown to increase tolerance to ischemic injury and improve cerebral perfusion status. Exosomes have a variety of activities, such as remodeling the extracellular matrix and transmitting signals to other cells. This study aimed to investigate the potential molecular mechanism of RIPC-mediated neuroprotection.

METHODS

Sixty adult male military personnel participants were divided into the control group (n = 30) and the RIPC group (n = 30). We analyzed the differential metabolites and proteins in the serum exosomes of RIPC participants and control subjects.

RESULTS

Eighty-seven differentially expressed serum exosomal metabolites were found between the RIPC and control groups, which were enriched in pathways related to tyrosine metabolism, sphingolipid metabolism, serotonergic synapses, and multiple neurodegeneration diseases. In addition, there were 75 differentially expressed exosomal proteins between RIPC participants and controls, which involved the regulation of insulin-like growth factor (IGF) transport, neutrophil degranulation, vesicle-mediated transport, etc. Furthermore, we found differentially expressed theobromine, cyclo gly-pro, hemopexin (HPX), and apolipoprotein A1 (ApoA1), which are associated with neuroprotective benefits in ischemia/reperfusion injury. In addition, five potential metabolite biomarkers, including ethyl salicylate, ethionamide, piperic acid, 2, 6-di-tert-butyl-4-hydroxymethylphenol and zerumbone, that separated RIPC from control individuals were identified.

CONCLUSION

Our data suggest that serum exosomal metabolites are promising biomarkers for RIPC, and our results provide a rich dataset and framework for future analyses of cerebral ischemia‒reperfusion injury under ischemia/reperfusion conditions.

Anti-depressant-like effects of rannasangpei and its active ingredient crocin-1 on chronic unpredictable mild stress mice

Major depressive disorder is one of the most common neuropsychiatric diseases and it is a global public health problem that leads to disabilities. Currently, there is a growing need to explore novel strategy to cure major depressive disorder due to the limitation of available treatments. Rannasangpei (RSNP) is a traditional Tibetan medicine which acts as a therapeutic agent in various acute or chronic diseases, including cardiovascular diseases and neurodegenerative diseases. Crocin-1 a coloring ingredient of saffron which exhibited anti-oxidative and anti-inflammatory properties. Here, we aimed to illustrate whether RSNP and its active ingredient crocin-1 rescue depressive-like phenotypes in chronic unpredictable mild stress (CUMS) induced mouse model of depression. Our results showed that peripheral administration of RSNP or crocin-1 ameliorated the depressive-like behaviors in CUMS-treated mice, as demonstrated by the forced swimming test and tail suspension test. Furthermore, RSNP or crocin-1 treatment reduced oxidative stress in the peripheral blood and hippocampus of the CUMS-treated mice. Additionally, the dysregulated immune system response, as demonstrated by the increased expression of the pro-inflammatory factors (tumor necrosis factor-α and interleukin-6) and the decreased expression of the anti-inflammatory factor-interleukin-10 in the prefrontal cortex and/or hippocampus of CUMS-treated mice, were at least partially restored by RSNP or crocin-1 treatment. RSNP or crocin-1 also restored apoptotic protein marker (Bcl-2 and Bax) levels in the prefrontal cortex and hippocampus of the CUMS-treated mice. Moreover, our data indicated that RSNP or crocin-1 increased astrocyte number and brain-derived neurotrophic factor levels in the hippocampus of CUMS-treated mice after RSNP or crocin-1 administration. Taken together, our study for the first time revealed an anti-depressant effect of RSNP and its active ingredient crocin-1 in a mouse model of depression, with involvement of oxidative stress, inflammatory response and apoptotic pathway.

MicroRNA schizophrenia: Etiology, biomarkers and therapeutic targets

The three sets of symptoms associated with schizophrenia-positive, negative, and cognitive-are burdensome and have serious effects on public health, which affects up to 1% of the population. It is now commonly believed that in addition to the traditional dopaminergic mesolimbic pathway, the etiology of schizophrenia also includes neuronal networks, such as glutamate, GABA, serotonin, BDNF, oxidative stress, inflammation and the immune system. Small noncoding RNA molecules called microRNAs (miRNAs) have come to light as possible participants in the pathophysiology of schizophrenia in recent years by having an impact on these systems. These small RNAs regulate the stability and translation of hundreds of target transcripts, which has an impact on the entire gene network. There may be improved approaches to treat and diagnose schizophrenia if it is understood how these changes in miRNAs alter the critical related signaling pathways that drive the development and progression of the illness.

Biological hypotheses, risk factors, and biomarkers of schizophrenia

Both the discovery of biomarkers of schizophrenia and the verification of biological hypotheses of schizophrenia are an essential part of the process of understanding the etiology of this mental disorder. Schizophrenia has long been considered a neurodevelopmental disease whose symptoms are caused by impaired synaptic signal transduction and brain neuroplasticity. Both the onset and chronic course of schizophrenia are associated with risk factors-induced disruption of brain function and the establishment of a new homeostatic setpoint characterized by biomarkers. Different risk factors and biomarkers can converge to the same symptoms of schizophrenia, suggesting that the primary cause of the disease can be highly individual. Schizophrenia-related biomarkers include measurable biochemical changes induced by stress (elevated allostatic load), mitochondrial dysfunction, neuroinflammation, oxidative and nitrosative stress, and circadian rhythm disturbances. Here is a summary of selected valid biological hypotheses of schizophrenia formulated based on risk factors and biomarkers, neurodevelopment, neuroplasticity, brain chemistry, and antipsychotic medication. The integrative neurodevelopmental-vulnerability-neurochemical model is based on current knowledge of the neurobiology of the onset and progression of the disease and the effects of antipsychotics and psychotomimetics and reflects the complex and multifactorial nature of schizophrenia.

Extracellular Vesicles in Mental Disorders: A State-of-art Review

Extracellular vesicles (EVs) are nanoscale particles with various physiological functions including mediating cellular communication in the central nervous system (CNS), which indicates a linkage between these particles and mental disorders such as schizophrenia, bipolar disorder, major depressive disorder, etc. To date, known characteristics of mental disorders are mainly neuroinflammation and dysfunctions of homeostasis in the CNS, and EVs are proven to be able to regulate these pathological processes. In addition, studies have found that some cargo of EVs, especially miRNAs, were significantly up- or down-regulated in patients with mental disorders. For many years, interest has been generated in exploring new diagnostic and therapeutic methods for mental disorders, but scale assessment and routine drug intervention are still the first-line applications so far. Therefore, underlying the downstream functions of EVs and their cargo may help uncover the pathogenetic mechanisms of mental disorders as well as provide novel biomarkers and therapeutic candidates. This review aims to address the connection between EVs and mental disorders, and discuss the current strategies that focus on EVs-related psychiatric detection and therapy.

Serum extracellular vesicle microRNA dysregulation and childhood trauma in adolescents with major depressive disorder

Major depressive disorder (MDD) seriously endangers adolescent mental and physical health. Extracellular vesicles (EVs) are mediators of cellular communication and are involved in many physiological brain processes. Although EV miRNAshave been implicated in adults with major psychiatric disorders, investigation into their effects in adolescent MDDremains scarce. In discovery set, we conducted a genome-wide miRNA sequencing of serum EVs from 9 untreated adolescents with MDD and 8 matched healthy controls (HCs), identifying 32 differentially expressed miRNAs (18 upregulated and 14 downregulated). In the validation set, 8 differentially expressed and highly enriched miRNAs were verified in independent samples using RT-PCR, with 4 (miR-450a-2-3p, miR-3691-5p, miR-556-3p, and miR-2115-3p) of the 8 miRNAs found to be significantly elevated in 34 untreated adolescents with MDD compared with 38 HCs and consistent with the sequencing results. After the Bonferroni correction, we found that three miRNAs (miR-450a-2-3p, miR-556-3p, and miR-2115-3p) were still significantly different. Among them, miR-450a-2-3p showed the most markeddifferential expression and was able to diagnose disease with 67.6% sensitivity and 84.2% specificity. Furthermore, miR-450a-2-3p partially mediated the associations between total childhood trauma, emotional abuse, and physical neglect and adolescent MDD. We also found that the combination of miR-450a-2-3p and emotional abuse could effectively diagnose MDD in adolescents with 82.4% sensitivity and 81.6% specificity. Our data demonstrate the association of serum EV miRNA dysregulation with MDD pathophysiology and, furthermore, show that miRNAs may mediate the relationship between early stress and MDD susceptibility. We also provide a valid integrated model for the diagnosis of adolescent MDD.

Assessment of expression of oxytocin-related lncRNAs in schizophrenia

BACKGROUND

Schizophrenia is a neuropsychiatric disorder characterized by a variety of clinical manifestations. This disorder has a complex inheritance. Oxytocinegic system has been shown to be implicated in the pathophysiology of schizophrenia. This system can alter social cognition through direct interaction with dopaminergic signaling, facilitating brain-stimulation reward, reduction of defense mechanism and stress reactivity, and modulation of social information processing through enhancing the greatness of social incentives. Long non-coding RNAs (lncRNAs) can affect activity of oxytocinegic system, thus contributing in the etiology of this disorder.

METHODS

We designed the current study to appraise dysregulation of nine oxytocin-associated mRNAs and lncRNAs in the venous blood of patients with schizophrenia.

RESULTS

Expression of FOS was up-regulated in total patients compared with total control group (Expression ratio (95% CI)= 13.64 (5.46-34.05), adjusted P value<0.0001) and in female patients compared with female control group (Expression ratio (95% CI)=32.13 (5.81-176), adjusted P value<0.0001). Such pattern was also seen for Lnc-FOXF1 (Expression ratio (95% CI)= 6.41 (2.84-14.3), adjusted P value<0.0001 and Expression ratio (95% CI)= 14.41 (3.2-64.44), adjusted P value<0.0001, respectively). ITPR1 was down-regulated in total patients compared with total controls (Expression ratio (95% CI)= 0.22 (0.076-0.67), adjusted P value=0.0079). ROC curve analyses demonstrated that FOS had the best AUC value among other genes in differentiation between patients and controls (AUC=0.78).

CONCLUSION

The above-mentioned results imply dysregulation of oxytocin-related genes in the circulatory blood of patients with schizophrenia.

Impact of clozapine on the expression of miR-675-3p in plasma exosomes derived from patients with schizophrenia

OBJECTIVES

Recently, the expression changes of microRNAs (miRNAs) in the serum exosomes (EXO) of schizophrenia (SCZ) have been reported. The aim of this study was to investigate the global expression changes of miRNA derived from the plasma EXO of patients with treatment-resistant schizophrenia (TRS) and the effects of clozapine on miRNA expression.

METHODS

Global miRNA expression changes in plasma EXO between TRS and controls were studied using microarray analysis. Then, miRNA expressions among TRS, non-TRS, and controls were confirmed with quantitative qPCR experiments. We also studied changes in EXO miRNA expression with in-vitro SH-SY5Y cells.

RESULTS

A microarray for miRNA expression analysis (nine controls vs. nine patients with TRS) revealed 13 up- and 18 downregulated miRNAs that were relevant to neuronal and brain development based on gene ontology analysis. Of those, upregulated miR-675-3p expression was successfully validated in the same cohort by qPCR experiments. Conversely, miR-675-3p expression levels were significantly decreased in the non-TRS cohort (50 controls vs. 50 patients without TRS without clozapine treatment).

CONCLUSIONS

We identified global miRNA changes in plasma EXO derived from patients with SCZ that were relevant to neuronal functions, among which, hsa-miR-675-3p expression was upregulated by clozapine treatment.

Emerging Role of Non-Coding RNAs in Senescence

Senescence is defined as a gradual weakening of functional features of a living organism. Cellular senescence is a process that is principally aimed to remove undesirable cells by prompting tissue remodeling. This process is also regarded as a defense mechanism induced by cellular damage. In the course of oncogenesis, senescence can limit tumor progression. However, senescence participates in the pathoetiology of several disorders such as fibrotic disorders, vascular disorders, diabetes, renal disorders and sarcopenia. Recent studies have revealed contribution of different classes of non-coding RNAs in the cellular senescence. Long non-coding RNAs, microRNAs and circular RNAs are three classes of these transcripts whose contributions in this process have been more investigated. In the current review, we summarize the available literature on the impact of these transcripts in the cellular senescence.

Exosome: The “Off-the-Shelf” Cellular Nanocomponent as a Potential Pathogenic Agent, a Disease Biomarker, and Neurotherapeutics

Exosomes are nanosized “off-the-shelf” lipid vesicles released by almost all cell types and play a significant role in cell–cell communication. Exosomes have already been proven to carry cell-specific cargos of proteins, lipids, miRNA, and noncoding RNA (ribonucleic acid). These vesicles can be selectively taken up by the neighboring cell and can regulate cellular functions. Herein, we have discussed three different roles of exosomes in neuroscience. First, we have discussed how exosomes play the role of a pathogenic agent as a part of cell–cell communication and transmit pathogens such as amyloid-beta (Aβ), further helping in the propagation of neurodegenerative and other neurological diseases. In the next section, the review talks about the role of exosomes in biomarker discovery in neurological disorders. Toward the end, we have reviewed how exosomes can be harnessed and engineered for therapeutic purposes in different brain diseases. This review is based on the current knowledge generated in this field and our comprehension of this domain.

Paeoniflorin Rescued MK-801-Induced Schizophrenia-Like Behaviors in Mice via Oxidative Stress Pathway

Schizophrenia (SCZ) affects approximately 1% population worldwide, and the first-line antipsychotics have partial reactivity or non-reactivity with side effects. Therefore, there is an urgent need to find more effective drugs. Paeoniflorin (PF) is the main effective component of traditional Chinese medicine from white peony, red peony and peony bark, which acts as a neuroprotective agent. The purpose of this study was to investigate whether PF can rescue MK-801 induced schizophrenia-like behavior in mice. Our results demonstrated that intragastric administration of PF ameliorated MK-801 induced schizophrenia–like behaviors in mice as demonstrated by prepulse inhibition of acoustic startle response, fear conditioning test for memory and open field test for activity. In contrast, the first-line antipsychotics-olanzapine reversed the prepulse inhibition deficits and hyperactivities, but not memory deficits, in the model mice. Further analysis showed that PF reduced oxidative stress in the MK-801-treated mice, as evidenced by the increased superoxide dismutase levels and decreased malondialdehyde levels in the blood of the model mice. In addition, PF treatment inhibited the expression of the apoptotic protein Bax and restored the expression of tyrosine hydroxylase in the brains of the model mice. in vitro data indicated that PF protected against oxidative stress induced neurotoxicity in the primary cultured hippocampal neurons. In conclusion, our results were the first to provide evidence that PF rescued schizophrenia-like behaviors (both positive symptoms and cognitive impairments) in rodents through oxidative stress pathway, and therefore provide a novel strategy for treatment of SCZ. However, more pre-clinical and clinical research are needed to translate the present findings into clinics for a treatment of schizophrenia.

Metabolomic Identification of Serum Exosome-Derived Biomarkers for Bipolar Disorder

Background

Exosomes are extracellular vesicles that play important roles in various physiological and pathological functions. Previous studies have demonstrated that exosome-derived contents are promising biomarkers to inform the pathogenesis and diagnosis of major depressive disorder and schizophrenia.

Methods

We used ultraperformance liquid chromatography-tandem mass spectrometry to analyze the differentially expressed metabolites in serum exosomes of patients with bipolar disorder (BD) and evaluated the potential of exosomal metabolites as biomarkers for BD.

Results

Our results showed 26 differentially expressed serum exosomal metabolites in patients with BD (n = 32) when compared with healthy control (HC) subjects (n = 40), and these differentially expressed metabolites were enriched in pathways related to sugar metabolism. We then utilized random forest classifier and identified 15 exosomal metabolites that can be used to classify samples from patients with BD and HC subjects with 0.838 accuracy (95% CI, 0.604–1.00) in the training set of participants. These 15 metabolites showed excellent performance in differentiating between patients with BD and HC subjects in the testing set of participants, with 0.971 accuracy (95% CI, 0.865–1.00). Importantly, the 15 exosomal metabolites also showed good to excellent performance in differentiating between BD patients and other major psychiatric diseases (major depressive disorder and schizophrenia).

Conclusion

Collectively, our findings for the first time revealed a potential role of exosomal metabolite dysregulations in the onset and/or development of BD and suggested that blood exosomal metabolites are strong candidates to inform the diagnosis of BD.

TINY IN SIZE, BIG IN IMPACT: EXTRACELLULAR VESICLES AS MODULATORS OF MOOD, ANXIETY AND NEURODEVELOPMENTAL DISORDERS

Extracellular Vesicles (EVs) are tiny vesicles used by cells as means of cellular communication, through which the function and state of a given cell can be changed. A body of evidence has suggested that EVs could be culprits in the development and progression of various types of diseases, including neurodegenerative diseases such as Multiple Sclerosis (MS) and Alzheimer's Disease (AD). Unsurprisingly, EVs have also been implicate in mood, anxiety and neurodevelopmental disorders, such as Major Depressive Disorder (MDD), anxiety disorder and Autism-Spectrum Disorder (ASD), respectively. Here, we review the state-of-art regarding the roles of EVs in the aforementioned diseases and focus on the mechanisms by which they can cause and worsen disease. Harnessing the knowledge of EVs is not only important to deliver different cargos to cells in a specific manner to treat these diseases, but also to establish reliable disease biomarkers, which will aid in the early disease diagnosis and treatment, increasing the chance of successful treatment.

The role of Exosomal miRNAs in cancer

Exosomal miRNAs have attracted much attention due to their critical role in regulating genes and the altered expression of miRNAs in virtually all cancers affecting humans (Sun et al. in Mol Cancer 17(1):14, 2018). Exosomal miRNAs modulate processes that interfere with cancer immunity and microenvironment, and are significantly involved in tumor growth, invasion, metastasis, angiogenesis and drug resistance. Fully investigating the detailed mechanism of miRNAs in the occurrence and development of various cancers could help not only in the treatment of cancers but also in the prevention of malignant diseases. The current review highlighted recently published advances regarding cancer-derived exosomes, e.g., sorting and delivery mechanisms for RNAs. Exosomal miRNAs that modulate cancer cell-to-cell communication, impacting tumor growth, angiogenesis, metastasis and multiple biological features, were discussed. Finally, the potential role of exosomal miRNAs as diagnostic and prognostic molecular markers was summarized, as well as their usefulness in detecting cancer resistance to therapeutic agents.

Analysis of circulating exosomes reveals a peripheral signature of astrocytic pathology in schizophrenia

OBJECTIVES

Extracellular vesicles, including exosomes, cross the blood brain barrier with their contents intact and can be assayed peripherally. Circulating exosomes have been studied in other neurodegenerative disorders, but there is scarce data in schizophrenia. This study aimed to examine neuropathology-relevant protein biomarkers in circulating plasma-derived exosomes from patients with schizophrenia and age- and sex-matched healthy controls.

METHODS

Nanoparticle tracking analysis was used to determine the size and concentration of exosomes. Exosomal membrane marker (CD9) and specific target cargo protein (glial fibrillary acid protein[GFAP], synaptophysin, and α-II-Spectrin) immunopositivity was examined using Western blot analyses with band intensity quantified. Methods were consistent with the 'Minimal information for studies of extracellular vesicles 2018' (MISEV2018) guidelines.

RESULTS

Exosomal GFAP concentration was significantly higher and α-II-Spectrin expression significantly lower in plasma obtained from schizophrenia patients. No group differences were observed between in plasma exosomal concentration and size or in CD9, calnexin, or synaptophysin levels.

CONCLUSIONS

Our results demonstrate a differential pattern of exosomal protein expression in schizophrenia compared to matched healthy controls, consistent with the hypothesised astroglial pathology in this disorder. These results warrant further examination of circulating exosomes as vehicles of novel peripheral biomarkers of disease in schizophrenia and other neuropsychiatric disorders.

Recommendations for pharmacotranscriptomic profiling of drug response in CNS disorders

Pharmacotranscriptomics is a still very new field of research that has just begun to flourish and promises to enable target discovery, inform biomarker and evaluate drug efficacy beyond pharmacogenomics. The aim of this review is to provide a critical overview of the biological foundations of transcriptomics, methodological approaches to transcriptomic studies, and their advantages and limitations. We present the different RNA species (rRNAs, tRNAs, mtRNAs, snRNAs, scRNAs, mRNAs, ncRNAs, LINE and SINE transcripts, circular RNAs, piRNAs, miRNAs, snoRNAs) and their potential for pharmacotranscriptomic studies as markers to predict treatment response in neurological and psychiatric disorders. We also review the accessible sources of RNA in patients peripheral blood cells (including platelets), plasma, microvesicles, exosomes, apoptotic bodies, and how those affect the integrity and relative abundances of RNAs and reflect the situation in the Central Nervous System (CNS). Finally, we discuss the suitability and indications of different techniques, such as microarrays and RNA-sequencing (RNA-Seq) techniques to understand gene expression differences or to reveal variation in expression levels of coding and non-coding genes. We conclude with some recommendations for future directions, e.g., gaps of knowledge and particular RNAs/tissues that have been overlooked.

CYP2D6 Gene Polymorphisms and Variable Metabolic Activity in Schizophrenia Patients of Han and Tibetan Populations

BACKGROUND

It has been suggested that the pharmacogenomic response to antipsychotics in schizophrenia patients partially contributed by drug metabolism enzyme polymorphism, including P450 2D6 (CYP2D6). However, CYP2D6 gene polymorphism across populations is largely unknown.

MATERIALS AND METHODS

Here, we investigated the differences of CYP2D6 gene polymorphism between Chinese Han and Tibetan schizophrenia patients. We analyzed five CYP2D6 gene related polymorphic locus in 103 patients with schizophrenia, including 60 Han ethnicity and 43 of Tibetan ethnicity, by nucleic acid MALDI-TOF.

RESULTS

Polymorphisms of rs1065852, rs1135840 and rs16947 were significantly different between Han and Tibetan patients. rs1065852 AA genotype had a low frequency of 9.3% in Tibetan patients in comparison with a frequency of 41.7% in Han patients, whereas rs16947 AA genotype had a low frequency of 3.3% in Han patients in comparison with a frequency of 34.9% in Tibetan patients. Additionally, the two patient groups showed distinct distribution of CYP2D6 haplotypes, with the highest frequency of *10/*10 and *1/*2 in Han and Tibetan patients, respectively. Furthermore, Han and Tibetan patients showed differential CYP2D6 metabolic activity.

DISCUSSION

Taken together, this exploratory study showed the differences of CYP2D6 gene and metabolic polymorphism between Han and Tibetan schizophrenia patients, and therefore may improve our understanding of the pharmacogenomic response to antipsychotics in schizophrenia patients across populations.

Fibroblast Growth Factor 9 as a Potential Biomarker for Schizophrenia

Preclinical and clinical studies have suggested that fibroblast growth factor (FGF) system contributed to the onset and development of schizophrenia (SCZ). However, there was no strong clinical evidence to link an individual FGF with SCZ. In this study, we aim to measure blood FGF9 levels in the patients with SCZ with and/or without medication, and test whether FGF9 has a potential to be a biomarker for SCZ. We recruited 130 patients with SCZ and 111 healthy individuals, and the ELISA and qRT-PCR assays were used to measure serum FGF9 levels in the participants. ELISA assay demonstrated that serum FGF9 protein levels were dramatically reduced in first-episode, drug-free patients, but not in chronically medicated patients when compared to healthy control subjects. Further analysis showed that treatment of the first-episode, drug-free SCZ patients with antipsychotics for 8 weeks significantly increased the serum FGF9 levels. In addition, we found that blood FGF9 mRNA levels were significantly lower in first-onset SCZ patients than controls. Under the receiver operating characteristic curve, the optimal cutoff values for FGF9 protein level as an indicator for diagnosis of drug-free SCZ patients was projected to be 166.4 pg/ml, which yielded a sensitivity of 0.955 and specificity of 0.86, and the area under the curve was 0.973 (95% CI, 0.954-0.993). Furthermore, FGF9 had good performance to discriminate between drug-free SCZ patients and chronically medicated patients, the optimal cutoff value for FGF9 concentration was projected to be 165.035 pg/ml with a sensitivity of 0.86 and specificity of 0.919, and the AUC was 0.968 (95% CI, 0.944, 0.991). Taken together, our results for the first time demonstrated the dysregulation of FGF9 in SCZ, and FGF9 has the potential to be served as a biomarker for SCZ.

Exosomes in schizophrenia: Pathophysiological mechanisms, biomarkers, and therapeutic targets

While schizophrenia (SCZ) is a devastating psychiatric disorder that detrimentally affects a significant portion of the worldwide population, its diagnosis is traditionally based on a relatively subjective assessment of current symptoms and medical history, devoid of an objective diagnostic modality. Antipsychotic medications are commonly used in the treatment of SCZ; however, some patients have low remission rates or forsake treatment due to the associated multiple side effects, resulting in recurrent episodes of the disease and poor prognosis. These situations imply that the diagnosis, treatment, and prognosis of SCZ need to be improved to increase the odds of a better outcome. Mounting studies have found that extracellular vesicles (EVs) play essential roles in the central nervous system. They are implicated in several mechanisms closely associated with SCZ such as cellular communication and synaptic plasticity. They can additionally exhibit neuroprotective and therapeutic effects. Since they possess distinct constituents, are readily available, easily detectable, and dependent on the internal environment, they can potentially serve as reliable biomarkers for disease diagnosis. Moreover, their biological configuration along with their ability to increase the bioavailability of their constituents and modulate intricate intracellular reactions in target cells, propel EVs as new targets for treatment. This review paper summarizes relevant research pertaining to the roles of EVs in SCZ, with the aim of improving insights into SCZ pathogenesis and evaluating EVs as potential biomarkers in the diagnosis and treatment of SCZ.

Altered Peripheral Immune Profiles in First-Episode, Drug-Free Patients With Schizophrenia: Response to Antipsychotic Medications

Previous research has demonstrated aberrations in the levels of inflammatory cytokines in patients with schizophrenia (SCZ), but most of the respective studies have tested a narrow set of inflammatory cytokines. Here, we aimed to analyze broad immune profiles in the peripheral blood of the first-episode drug-free (FEDF) patients with SCZ at baseline and after an 8-week treatment with atypical antipsychotics. Serum samples from 24 FEDF patients with SCZ and 25 healthy control (HC) subjects were tested using Luminex multiplex analysis for 30 cytokines, chemokines, and growth factors. Multiple comparison tests demonstrated that interleukin-2 (IL-2), IL-4, interferon-gamma (IFN-γ), monokine induced by IFN-γ, and granulocyte colony-stimulating factor (G-CSF) levels were significantly increased, whereas those of the epidermal growth factor were significantly decreased in the FEDF patients with SCZ. Moreover, the levels of the 6 dysregulated cytokines as well as those of 12 additional soluble factors in FEDF patients with SCZ were significantly decreased after 8 weeks of antipsychotic treatment. Furthermore, the transcription of G-CSF and IFN-γ was significantly increased in FEDF patients with SCZ when compared with controls, and G-CSF and IFN-γ mRNA levels were highly correlated with their respective protein concentrations. Receiver operating characteristic curves showed that G-CSF and IFN-γ had good performance in differentiating between FEDF patients with SCZ and HC subjects. Taken together, our data revealed that FEDF patients with SCZ were accompanied by a unique pattern of immune profile, and antipsychotic medications seemed to suppress the immune function in these patients, which could be used to develop novel targets for the diagnosis and treatment of SCZ.

MiR-574-5P, miR-1827, and miR-4429 as Potential Biomarkers for Schizophrenia

Schizophrenia is a severe chronic debilitating disorder with millions of affected individuals. Diagnosis is based on clinical presentations, which are made when the progressive disease has appeared. Early diagnosis may help improve the clinical outcomes and response to treatments. Lack of a reliable molecular diagnostic invokes the identification of novel biomarkers. To elucidate the molecular basis of the disease, in this study we used two mRNA expression arrays, including GSE93987 and GSE38485, and one miRNA array, GSE54914, and meta-analysis was conducted for evaluation of mRNA expression arrays via metaDE package. Using WGCNA package, we performed network analysis for both mRNA expression arrays separately. Then, we constructed protein-protein interaction network for significant modules. Limma package was employed to analyze the miRNA array for identification of dysregulated miRNAs (DEMs). Using genes of significant modules and DEMs, a mRNA-miRNA network was constructed and hub genes and miRNAs were identified. To confirm the dysregulated genes, expression values were evaluated through available datasets including GSE62333, GSE93987, and GSE38485. The ability of the detected hub miRNAs to discriminate schizophrenia from healthy controls was evaluated by assessing the receiver-operating curve. Finally, the expression levels of genes and miRNAs were evaluated in 40 schizophrenia patients compared with healthy controls via Real-Time PCR. The results confirmed dysregulation of hsa-miR-574-5P, hsa-miR-1827, hsa-miR-4429, CREBRF, ARPP19, TGFBR2, and YWHAZ in blood samples of schizophrenia patients. In conclusion, three miRNAs including hsa-miR-574-5P, hsa-miR-1827, and hsa-miR-4429 are suggested as potential biomarkers for diagnosis of schizophrenia.

miR-132-3p, miR-106b-5p, and miR-19b-3p Are Associated with Brain-Derived Neurotrophic Factor Production and Clinical Activity in Multiple Sclerosis: A Pilot Study

Introduction: Brain-derived neurotrophic factor (BDNF) levels are reduced in advanced stages of multiple sclerosis (MS) and may be associated with reduced regenerative capability in progressive MS. This has brought increased attention to factors regulating BDNF production in MS. Our aim was to investigate the link between neurotrophin-regulating microRNAs (miRNA) and disease progression in MS. Materials and Methods: Serum levels of BDNF and peripheral blood mononuclear cell (PBMC) expression levels of miR-132-3p, miR-106b-5p and miR-19b-3p were respectively measured by ELISA and real time PCR in twelve relapsing remitting MS (RRMS) patients, seven secondary progressive MS (SPMS) patients and fourteen healthy controls. Results: Serum BDNF levels were significantly reduced in SPMS patients, while selected miRNAs were significantly upregulated in PBMC of RRMS and SPMS patients. miR-106b-5p and miR-19b-3p respectively showed the highest sensitivity and specificity for MS diagnosis by receiver operating characteristic curve analysis. There was a negative correlation between levels of BDNF and the miRNAs in RRMS. Likewise, levels of BDNF and the investigated miRNAs showed positive and negative correlations respectively with the expanded disability status scale in RRMS and SPMS patients. miR-132-3p and miR-106b-5p levels showed positive correlations with the progression index in SPMS patients. Conclusion: Our results suggest that increased disability is associated with downregulation of miR-132-3p, miR-106b-5p and miR-19b-3p in RRMS patients and putatively promotes increased production of neuroprotective BDNF as a compensatory mechanism. This link between the investigated miRNAs and BDNF in RRMS does not appears to hold for SPMS. This might be one of the factors contributing to reduced regenerative ability in the progressive stage of MS.

DNA Methylation and Schizophrenia: Current Literature and Future Perspective

Schizophrenia is a neuropsychiatric disorder characterized by dissociation of thoughts, idea, identity, and emotions. It has no central pathophysiological mechanism and precise diagnostic markers. Despite its high heritability, there are also environmental factors implicated in the development of schizophrenia. Epigenetic factors are thought to mediate the effects of environmental factors in the development of the disorder. Epigenetic modifications like DNA methylation are a risk factor for schizophrenia. Targeted gene approach studies attempted to find candidate gene methylation, but the results are contradictory. Genome-wide methylation studies are insufficient in literature and the available data do not cover different populations like the African populations. The current genome-wide studies have limitations related to the sample and methods used. Studies are required to control for these limitations. Integration of DNA methylation, gene expression, and their effects are important in the understanding of the development of schizophrenia and search for biomarkers. There are currently no precise and functional biomarkers for the disorder. Several epigenetic markers have been reported to be common in functional and peripheral tissue. This makes the peripheral tissue epigenetic changes a surrogate of functional tissue, suggesting common epigenetic alteration can be used as biomarkers of schizophrenia in peripheral tissue.

Role of Exosomes in Brain Diseases

Exosomes are a subset of extracellular vesicles that act as messengers to facilitate communication between cells. Non-coding RNAs, proteins, lipids, and microRNAs are delivered by the exosomes to target molecules (such as proteins, mRNAs, or DNA) of host cells, thereby playing a key role in the maintenance of normal brain function. However, exosomes are also involved in the occurrence, prognosis, and clinical treatment of brain diseases, such as Alzheimer's disease, Parkinson's disease, stroke, and traumatic brain injury. In this review, we have summarized novel findings that elucidate the role of exosomes in the occurrence, prognosis, and treatment of brain diseases.

mRNA Expression of the CUB and Sushi Multiple Domains 1 (CSMD1) and Its Serum Protein Level as Predictors for Psychosis in the Familial High-Risk Children and Young Adults

Background: Schizophrenia (SCZ) is still a challenging, refractory, and severe disorder. It is not a fully understood disease with genetic and epigenetic susceptibility and about 80% substantial heritability. The CUB and Sushi multiple domains 1 (CSMD1) gene is implicated in neurogenesis, memory, immunity, neuropsychology, and monoamine metabolism. Thus, it is one of the powerful genes involved in the pathogenesis of SCZ. Purpose: To evaluate the possible role of the CSMD1 gene's mRNA expression and its serum protein as markers for the early diagnosis of the first-episode SCZ in familial high-risk (FHR) Egyptian children and young adults. Subjects and methods: This case-control study included 80 first-episode drug-naïve SCZ patients from FHR Egyptian children and young adults and 80 healthy participants, as controls, from the FHR-susceptible children and young adults but did not develop SCZ. In this study, the CSMD1 gene's mRNA expression and CSMD1 serum levels were measured in the peripheral blood, and these levels were correlated with the lipid profile of the study populations. Results: The CSMD1 gene's mRNA expression and its' protein levels were significantly decreased in the SCZ patients compared to controls. The receiver operating characteristic (ROC) curve analysis succeeded in distinguishing SCZ patients from those not having SCZ using cutoff points of ≤0.711 and ≤4.83 ng/mL for the CSMD1 gene's mRNA expression and serum protein level, respectively. At these levels, the diagnostic sensitivities were 93.75 and 91.25%; specificity was 92.5%; positive predictive value (PPV) were 92.6 and 92.4%; and negative predictive values (NPVs) were 93.7 and 91.4%, respectively. Also, the ROC curve analysis succeeded in discriminating those with suicidal tendencies. Conclusion: CSMD1 gene's mRNA expression might be a reliable and early diagnostic predictor of first-episode SCZ in the FHR Egyptian children and young adults.

Abnormal expression profile of plasma-derived exosomal microRNAs in patients with treatment-resistant depression

Whether microRNAs (miRNAs) from plasma exosomes might be dysregulated in patients with depression, especially treatment-resistant depression (TRD), remains unclear, based on study of which novel biomarkers and therapeutic targets could be discovered. To this end, a small sample study was performed by isolation of plasma exosomes from patients with TRD diagnosed by Hamilton scale. In this study, 4 peripheral plasma samples from patients with TRD and 4 healthy controls were collected for extraction of plasma exosomes. Exosomal miRNAs were analyzed by miRNA sequencing, followed by image collection, expression difference analysis, target gene GO enrichment analysis, and KEGG pathway enrichment analysis. Compared with the healthy controls, 2 miRNAs in the plasma exosomes of patients with TRD showed significant differences in expression, among which has-miR-335-5p were significantly upregulated and has-miR-1292-3p were significantly downregulated. Go and KEGG analysis showed that dysregulated miRNAs affect postsynaptic density and axonogenesis as well as the signaling pathway of axon formation and cell growths. The identification of these miRNAs and their target genes may provide novel biomarkers for improving diagnosis accuracy and treatment effectiveness of TRD.

Cataloging recent advances in epigenetic alterations in major mental disorders and autism

During the last two decades, diverse epigenetic modifications including DNA methylation, histone modifications, RNA editing and miRNA dysregulation have been associated with psychiatric disorders. A few years ago, in a review we outlined the most common epigenetic alterations in major psychiatric disorders (e.g., aberrant DNA methylation of DTNBP1, HTR2A, RELN, MB-COMT and PPP3CC, and increased expression of miR-34a and miR-181b). Recent follow-up studies have uncovered other DNA methylation aberrations affecting several genes in mental disorders, in addition to dysregulation of many miRNAs. Here, we provide an update on new epigenetic findings and highlight potential origin of the diversity and inconsistencies, focusing on drug effects, tissue/cell specificity of epigenetic landscape and discuss shortcomings of the current diagnostic criteria in mental disorders.

Research Progress on the Correlation Between Epigenetics and Schizophrenia

Purpose of the Review

Nowadays, the incidence of schizophrenia is noticeably increased. If left undiagnosed and untreated, it will lead to impaired social functions, repeated hospital admissions, decline in quality of life and life expectancy. However, the diagnosis of schizophrenia is complicated and challenging. Both genetic and environmental factors are considered as important contributors to the development and progression of this disorder. The environmental factors have been linked to changes in gene expression through epigenetic modulations, which have raised more and more research interests in recent years. This review article is to summarize the current findings and understanding of epigenetic modulation associated with pathogenesis of schizophrenia, aiming to provide useful information for further research in developing biomarkers for schizophrenia.

Recent Findings

Three major types of epigenetic modulations have been described in this article. Firstly, both DNA hypermethylation and hypomethylated have been associated with schizophrenia via analyzing post-mortem brain tissues and peripheral blood of patients. Specific changes of non-coding RNAs, particularly microRNAs and long-chain non-coding RNAs, have been observed in central and peripheral samples of schizophrenia patients, indicating their significant diagnostic value for the disease, and may also potentially predict treatment response. The correlation between histone modification and schizophrenia, however, is largely unclear.

Summary

Epigenetic modulations, including DNA methylation, ncRNA transcriptional regulation and histone modification, play an important role in the pathogenesis of schizophrenia. Therefore, tests of these epigenetic alterations may be utilized to assist in the diagnosis and determination of strategies of individualized treatment in clinical practice.

A Review on the Expression Pattern of Non-coding RNAs in Patients With Schizophrenia: With a Special Focus on Peripheral Blood as a Source of Expression Analysis

Schizophrenia is a destructive neuropsychiatric disease with a median prevalence of 4.0 per 1,000 during the whole life. Genome-wide association studies have shown the role of copy number variants (generally deletions) and certain alleles of common single nucleotide polymorphisms in the pathogenesis of schizophrenia. This disorder predominantly follows the polygenic inheritance model. Schizophrenia has also been linked with various alterations in the transcript and protein content of the brain tissue. Recent studies indicate that alterations in non-coding RNAs (ncRNAs) signature underlie a proportion of this dysregulation. High throughput microarray investigations have demonstrated momentous alterations in the expression of long non-coding RNAs (lncRNA) and microRNAs (miRNAs) in the circulation or post-mortem brain tissues of patients with schizophrenia compared with control samples. While Gomafu, PINT, GAS5, TCONS_l2_00021339, IFNG-AS1, FAS-AS1, PVT1, and TUG1 are among down-regulated lncRNAs in schizophrenia, MEG3, THRIL, HOXA-AS2, Linc-ROR, SPRY4-IT1, UCA1, and MALAT1 have been up-regulated in these patients. Moreover, several miRNAs, such as miR-30e, miR-130b, hsa-miR-130b, miR-193a-3p, hsa-miR-193a-3p, hsa-miR-181b, hsa-miR-34a, hsa-miR-346, and hsa-miR-7 have been shown to be dysregulated in blood or brain samples of patients with schizophrenia. Dysregulation of these transcripts in schizophrenia not only provides insight into the pathogenic processes of this disorder, it also suggests these transcripts could serve as diagnostic markers for schizophrenia. In the present paper, we explore the changes in the expression of miRNAs and lncRNAs in patients with schizophrenia.

MicroRNA-dependent control of neuroplasticity in affective disorders

Affective disorders are a group of neuropsychiatric disorders characterized by severe mood dysregulations accompanied by sleep, eating, cognitive, and attention disturbances, as well as recurring thoughts of suicide. Clinical studies consistently show that affective disorders are associated with reduced size of brain regions critical for mood and cognition, neuronal atrophy, and synaptic loss in these regions. However, the molecular mechanisms that mediate these changes and thereby increase the susceptibility to develop affective disorders remain poorly understood. MicroRNAs (miRNAs or miRs) are small regulatory RNAs that repress gene expression by binding to the 3'UTR of mRNAs. They have the ability to bind to hundreds of target mRNAs and to regulate entire gene networks and cellular pathways implicated in brain function and plasticity, many of them conserved in humans and other animals. In rodents, miRNAs regulate synaptic plasticity by controlling the morphology of dendrites and spines and the expression of neurotransmitter receptors. Furthermore, dysregulated miRNA expression is frequently observed in patients suffering from affective disorders. Together, multiple lines of evidence suggest a link between miRNA dysfunction and affective disorder pathology, providing a rationale to consider miRNAs as therapeutic tools or molecular biomarkers. This review aims to highlight the most recent and functionally relevant studies that contributed to a better understanding of miRNA function in the development and pathogenesis of affective disorders. We focused on in vivo functional studies, which demonstrate that miRNAs control higher brain functions, including mood and cognition, in rodents, and that their dysregulation causes disease-related behaviors.

Exosome Transplantation From Patients With Schizophrenia Causes Schizophrenia-Relevant Behaviors in Mice: An Integrative Multi-omics Data Analysis

Exosomes are involved in the pathophysiology of neuropsychiatric diseases, but the role of exosomes in schizophrenia (SCZ) is unclear. Here, we demonstrate that transplantation of serum exosomes from SCZ patients into mice caused behavioral abnormalities such as deficits in prepulse inhibition and sociability, hyperactivity, and anxiogenesis. A comparative bioinformatics analysis suggested shared and distinct differentially expressed genes (DEGs) and enriched molecular pathways in the brains of SCZ exosome-recipient mice, methylazoxymethanol acetate-treated rats, and SCZ patients, which correlates evidence of altered prefrontal-hippocampal functional coherence in SCZ. A large proportion of SCZ-relevant DEGs in the exosome-recipient mice were targets of DE exosomal miRNAs in SCZ patients. Furthermore, we identified 20 hub genes for SCZ risk genes, including BDNF and NRG1, which were DE miRNA targets in SCZ. Collectively, our study suggests that SCZ exosome transplantation caused SCZ-relevant behaviors in mice, and epigenetic regulation may contribute to the phenotypes in the SCZ exosome-recipient mice. Our results may provide a potential animal model and novel therapeutic targets for SCZ.

Function of exosomes in neurological disorders and brain tumors

Exosomes are a subtype of extracellular vesicles released from different cell types including those in the nervous system, and are enriched in a variety of bioactive molecules such as RNAs, proteins and lipids. Numerous studies have indicated that exosomes play a critical role in many physiological and pathological activities by facilitating intercellular communication and modulating cells' responses to external environments. Particularly in the central nervous system, exosomes have been implicated to play a role in many neurological disorders such as abnormal neuronal development, neurodegenerative diseases, epilepsy, mental disorders, stroke, brain injury and brain cancer. Since exosomes recapitulate the characteristics of the parental cells and have the capacity to cross the blood-brain barrier, their cargo can serve as potential biomarkers for early diagnosis and clinical assessment of disease treatment. In this review, we describe the latest findings and current knowledge of the roles exosomes play in various neurological disorders and brain cancer, as well as their application as promising biomarkers. The potential use of exosomes to deliver therapeutic molecules to treat diseases of the central nervous system is also discussed.

Secreted Extracellular Vesicle Molecular Cargo as a Novel Liquid Biopsy Diagnostics of Central Nervous System Diseases

Secreted extracellular vesicles (EVs) are heterogeneous cell-derived membranous granules which carry a large diversity of molecules and participate in intercellular communication by transferring these molecules to target cells by endocytosis. In the last decade, EVs’ role in several pathological conditions, from etiology to disease progression or therapy evasion, has been consolidated, including in central nervous system (CNS)-related disorders. For this review, we performed a systematic search of original works published, reporting the presence of molecular components expressed in the CNS via EVs, which have been purified from plasma, serum or cerebrospinal fluid. Our aim is to provide a list of molecular EV components that have been identified from both nonpathological conditions and the most common CNS-related disorders. We discuss the methods used to isolate and enrich EVs from specific CNS-cells and the relevance of its components in each disease context.

Epigenetic Modifications in Schizophrenia and Related Disorders: Molecular Scars of Environmental Exposures and Source of Phenotypic Variability

Epigenetic modifications are increasingly recognized to play a role in the etiology and pathophysiology of schizophrenia and other psychiatric disorders with developmental origins. Here, we summarize clinical and preclinical findings of epigenetic alterations in schizophrenia and relevant disease models and discuss their putative origin. Recent findings suggest that certain schizophrenia risk loci can influence stochastic variation in gene expression through epigenetic processes, highlighting the intricate interaction between genetic and epigenetic control of neurodevelopmental trajectories. In addition, a substantial portion of epigenetic alterations in schizophrenia and related disorders may be acquired through environmental factors and may be manifested as molecular "scars." Some of these scars can influence brain functions throughout the entire lifespan and may even be transmitted across generations via epigenetic germline inheritance. Epigenetic modifications, whether caused by genetic or environmental factors, are plausible molecular sources of phenotypic heterogeneity and offer a target for therapeutic interventions. The further elucidation of epigenetic modifications thus may increase our knowledge regarding schizophrenia's heterogeneous etiology and pathophysiology and, in the long term, may advance personalized treatments through the use of biomarker-guided epigenetic interventions.

Extracellular Vesicles in Neurological Disorders

The role of extracellular vesicles (EVs) in the central nervous system, and in particular the brain, is a rapidly growing research area. Importantly, the role for EVs in the nervous system spans from early development through to old age, with EVs being associated with several different neurological disorders. To date, researchers have been studying the function of EVs in the nervous system in three major areas: (i) the role of EVs in promoting disease pathways, (ii) the ability of EVs to be used as a diagnostic tool to identify cellular changes in the nervous system, and (iii) the potential use of EVs as therapeutic tools for the delivery of biomolecules or drugs to the nervous system. In each of these settings the analysis and use of EVs performs a different function, highlighting the breadth of areas in which the EV field is applicable. A key aspect of EV biology is the ability of vesicles to cross biological barriers, in particular the blood brain barrier. This allows for the measurement of serum EVs that contain information about cells in the brain, or alternatively, allows for the delivery of biomolecules that are packaged within EVs for therapeutic use.

Biomarkers for suicidal behavior: miRNAs and their potential for diagnostics through liquid biopsy - a systematic review

Background: Given that approximately 70% of miRNAs in the body are neuronal, we critically assessed current studies on miRNAs and suicidal behavior. Materials & Methods: To further define the role of miRNAs in suicide, we searched for studies on extracellular vesicles (exosomes) because miRNAs are particularly enriched in exosomes. miRNAs also have important physiological roles, and they can cross the blood-brain barrier and participate in cell-to-cell communication with both nearby and distant cells. Results & Conclusion: This critical assessment suggests that several miRNAs can be closely related to neurophysiology, suicidal behavior, and psychiatric disorders. However, clear overlap is poor due to either different methodologies applied or to molecular differences between suicidal behaviors and studied psychiatric disorders.

Blood Exosomes Have Neuroprotective Effects in a Mouse Model of Parkinson's Disease

Parkinson's disease (PD) is a common and complex neurodegenerative disease; the pathogenesis of which is still uncertain. Exosomes, nanosized extracellular vesicles, have been suggested to participate in the pathogenesis of PD, but their role is unknown. Here, a metabolomic analysis of serum and brain exosomes showed differentially expressed metabolites between 1-Methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine hydrochloride- (MPTP-) induced PD mice and control mice, such as oxidized lipids, vitamins, and cholesterol. These metabolites were enriched in coenzyme, nicotinamide, and amino acid pathways related to PD, and they could be served as preclinical biomarkers. We further found that blood-derived exosomes from healthy volunteers alleviated impaired motor coordination in MPTP-treated mice. Results from immunohistochemistry and western blotting indicated that the loss of dopaminergic neurons in substantia nigra and striatum of PD model mice was rescued by the exosome treatment. The exosome treatment also restored the homeostasis of oxidative stress, neuroinflammation, and cell apoptosis in the model mice. These results suggest that exosomes are important mediators for PD pathogenesis, and exosomes are promising targets for the diagnosis and treatment of PD.

Metabolomic Identification of Exosome-Derived Biomarkers for Schizophrenia: A Large Multicenter Study

Exosomes have been suggested as promising targets for the diagnosis and treatment of neurological diseases, including schizophrenia (SCZ), but the potential role of exosome-derived metabolites in these diseases was rarely studied. Using ultra-performance liquid chromatography-tandem mass spectrometry, we performed the first metabolomic study of serum-derived exosomes from patients with SCZ. Our sample comprised 385 patients and 332 healthy controls recruited from 3 clinical centers and 4 independent cohorts. We identified 25 perturbed metabolites in patients that can be used to classify samples from patients and control participants with 95.7% accuracy (95% CI: 92.6%-98.9%) in the training samples (78 patients and 66 controls). These metabolites also showed good to excellent performance in differentiating between patients and controls in the 3 test sets of participants, with accuracies 91.0% (95% CI: 85.7%-96.3%; 107 patients and 62 controls), 82.7% (95% CI: 77.6%-87.9%; 104 patients and 142 controls), and 99.0% (95% CI: 97.7%-100%; 96 patients and 62 controls), respectively. Bioinformatic analysis suggested that these metabolites were enriched in pathways implicated in SCZ, such as glycerophospholipid metabolism. Taken together, our findings support a role for exosomal metabolite dysregulation in the pathophysiology of SCZ and indicate a strong potential for exosome-derived metabolites to inform the diagnosis of SCZ.

Neurotransmitter system aberrations in patients with drug addiction

Drug dependence may affect the neurotransmitter system levels in the human body. This study recruited 113 healthy control subjects, 118 heroin-dependent patients and 118 methamphetamine-dependent patients and examined the serum 5-HT, dopamine, glutamate and norepinephrine levels in the 349 volunteers. ELISA assays demonstrated that the serum 5-HT levels were significantly reduced in the drug-dependent patients, whereas the serum dopamine and glutamate levels were both significantly increased in the drug-dependent patients when compared with control subjects. In contrast, the norepinephrine levels did not exhibit a significant difference between the drug-dependent and control subjects. We also used qRT-PCR to analyze the transcriptional expression levels of 5-HT_1A, 5-HT_1B, dopmaine-D1 and dopamine-D2 receptors in the blood of drug-dependent patients and controls, and the results show that only 5-HT_1B receptor levels were dysfunctional in the heroin abusers. In addition, our results suggest that serum 5-HT, dopamine, and glutamate levels had the potential to differ between drug abusers and controls, and combining those three potential biomarkers provided an accurate means to differentiate between the drug-dependent and control subjects. Taken together, our study reveals a differential profile of neurotransmitters in the heroin-dependent patients and methamphetamine-dependent patients, and this revelation may contribute to understanding the pathophysiology of drug addiction.

Epigenomic Dysregulation in Schizophrenia: In Search of Disease Etiology and Biomarkers

Schizophrenia is a severe psychiatric disorder with a complex array of signs and symptoms that causes very significant disability in young people. While schizophrenia has a strong genetic component, with heritability around 80%, there is also a very significant range of environmental exposures and stressors that have been implicated in disease development and neuropathology, such as maternal immune infection, obstetric complications, childhood trauma and cannabis exposure. It is postulated that epigenetic factors, as well as regulatory non-coding RNAs, mediate the effects of these environmental stressors. In this review, we explore the most well-known epigenetic marks, including DNA methylation and histone modification, along with emerging RNA mediators of epigenomic state, including miRNAs and lncRNAs, and discuss their collective potential for involvement in the pathophysiology of schizophrenia implicated through the postmortem analysis of brain tissue. Given that peripheral tissues, such as blood, saliva, and olfactory epithelium have the same genetic composition and are exposed to many of the same environmental exposures, we also examine some studies supporting the application of peripheral tissues for epigenomic biomarker discovery in schizophrenia. Finally, we provide some perspective on how these biomarkers may be utilized to capture a signature of past events that informs future treatment.

Exosomes from patients with major depression cause depressive-like behaviors in mice with involvement of miR-139-5p-regulated neurogenesis

Exosomal microRNAs (miRNAs) have been suggested to participate in the pathogenesis of neuropsychiatric diseases, but their role in major depressive disorder (MDD) is unknown. We performed a genome-wide miRNA expression profiling of blood-derived exosomes from MDD patients and control subjects and revealed the top differentially expressed exosomal miRNA, i.e. hsa-miR-139-5p (upregulation), had good performance to differentiate between MDD patients and controls. Tail vein injection of blood exosomes isolated from MDD patients into normal mice caused their depressive-like behaviors as determined by the forced swimming, tail suspension, and novelty suppressed feeding tests, and injection of blood exosomes isolated from healthy volunteers into unpredictable mild stress (CUMS)-treated mice alleviated their depressive-like behaviors. CUMS mice also showed significantly increased blood and brain levels of exosomal miR-139-5p. Furthermore, the depressive-like behaviors in CUMS-treated mice were rescued by intranasal injection of miR-139-5p antagomir, suggesting that increased exosomal miR-139-5p levels may mediate stress-induced depression-like behavior in mice. Both exosome treatment and miR-139-5p antagomir treatment increased hippocampal neurogenesis in the CUMS-treated mice, and treatment of exosome from MDD patients decreased hippocampal neurogenesis in the normal mice. The role of miR-139-5p in neurogenesis was validated by in vitro experiments, demonstrating that miR-139-5p is a negative regulator for neural stem cell proliferation and neuronal differentiation. Our findings together suggest that exosomes from patients with major depression caused depressive-like behaviors in mice with involvement of miR-139-5p-regulated neurogenesis. Therefore, exosomal miRNAs are promising targets for the diagnosis and treatment of MDD.

A Network Analysis of Epigenetic and Transcriptional Regulation in a Neurodevelopmental Rat Model of Schizophrenia With Implications for Translational Research

Prenatal administration of mitotoxin methylazoxymethanol acetate (MAM) in rats produces behavioral, pharmacological, and anatomical abnormalities once offspring reach adulthood, thus establishing a widely used neurodevelopmental model of schizophrenia. However, the molecular aspects underlying this disease model are not well understood. Therefore, this study examines epigenetic and transcriptional dysregulation in the prefrontal cortex and hippocampus of MAM rats as these are brain regions closely associated with schizophrenia pathogenesis. Upon sequencing messenger and microRNA (mRNA and miRNA, respectively), differential expression was revealed in the prefrontal cortex and hippocampus between MAM- and saline-treated rats; sequencing data were validated by qualitative real-time polymerase chain reaction. Bioinformatic analyses demonstrated that the differentially expressed (DE) genes were strongly enriched in interactive pathways related to schizophrenia, including chemical synaptic transmission, cognition, and inflammatory responses; also, the potential target genes of the DE miRNAs were enriched in pathways related to synapses and inflammation. The blood of schizophrenia patients and healthy controls was further analyzed for several top DE mRNAs: DOPA decarboxylase, ret proto-oncogene, Fc receptor-like 2, interferon lambda receptor 1, and myxovirus (influenza virus) resistance 2. The results demonstrated that the expression of these genes was dysregulated in patients with schizophrenia; combining these mRNAs sufficiently differentiated schizophrenia patients from controls. Taken together, this study suggests that the MAM model has the potential to reproduce hippocampus and prefrontal cortex abnormalities, relevant to schizophrenia, at the epigenetic and transcriptional levels. These data also provide novel targets for schizophrenia diagnoses and treatments.

Circular RNA in Schizophrenia and Depression

Schizophrenia (SZ) and depression (DEP) are two common major psychiatric disorders that are associated with high risk of suicide. These disorders affect not only physical and mental health, but they also affect the social function of the individual. However, diagnoses of SZ and DEP are mainly based on symptomatic changes and the clinical experience of psychiatrists. These rather subjective measures can induce misdiagnoses and missed diagnoses. Therefore, it is necessary to further explore objective indexes for improving the early diagnoses and prognoses of SZ and DEP. Current research indicates that non-coding RNA (ncRNA) may play a role in the occurrence and development of SZ and DEP. Circular RNA (circRNA), as an important component of ncRNA, is associated with many biological functions, especially post-transcriptional regulation. Since circRNA is easily detected in peripheral blood and has a high degree of spatiotemporal tissue specificity and stability, these attributes provide us with a new idea to further explore the potential value for the diagnosis and treatment of SZ and DEP. Here, we summarize the classification, characteristics, and biological functions of circRNA and the most significant results of experimental studies, aiming to highlight the involvement of circRNA in SZ and DEP.

Serum Exosome-Derived miR-139-5p as a Potential Biomarker for Major Depressive Disorder

BACKGROUND

MicroRNAs (miRs) have been suggested to be biomarkers to inform the diagnosis of major depressive disorder (MDD). We have previously shown that exosome-derived miR-139-5p had potential in differentiating between patients with MDD and healthy control (HC) subjects.

MATERIALS AND METHODS

To validate the potential of exosome-derived miR-139-5p as a biomarker for MDD, here we recruited 30 patients with MDD and 30 HC subjects, and used TaqMan probes to detect serum exosomal miR-139-5p levels.

RESULTS

The data showed that patients with MDD had significantly increased exosomal miR-139-5p levels when compared with controls. Correlation analysis suggested that sex, age, and body mass index did not significantly affect blood exosomal miR-139-5p levels in the tested subjects. The ROC curve showed that serum-derived miR-139-5p had reasonable performance in discriminating patients with MDD and HC subjects, with a sensitivity of 0.867 and specificity of 0.767, and the AUC was 0.807.

DISCUSSION

Taken together, these results demonstrated that patients with MDD were accompanied by significantly increased blood exosomal miR-139-5p levels, and exosomal miR-139-5p is a promising biomarker for the diagnosis of MDD.

Peripheral blood BDNF-TrkB signaling in first-episode, drug-free patients with major depressive disorder and schizophrenia

Brain-derived neurotrophic factor (BDNF) has been implicated in the pathogenesis of psychiatric disorders, and studies have shown BDNF aberrations in major psychiatric diseases including schizophrenia (SCZ) and major depressive disorder (MDD). However, data from clinical studies were inconsistent. In this study, we recruited 34 patients with MDD, 77 patients with SCZ and 65 healthy control (HC) subjects to clarify the circulating BDNF levels in MDD and SCZ patients, and to assess whether serum BDNF levels were associated with the disease severity. Our results showed that serum BDNF levels were significantly decreased in the patients with SCZ (Mean difference = -4.517, 95%CI of difference = -7.854 to -1.180, p < 0.01) and MDD (Mean difference = -5.699, 95%CI of difference = -9.892 to -1.506, p < 0.01) when compared with HC subjects. Sub-group analyses suggested that BDNF levels were significantly reduced in the female SCZ (Mean difference = -5.700, 95%CI of difference = -10.21 to -1.189, p < 0.01) and MDD (Mean difference = -5.840, 95%CI of difference = -10.66 to -1.019, p < 0.05) patients, but not in male patients. Further analyses indicated that serum BDNF levels were not correlated with disease severity of MDD and SCZ. In addition, the transcriptional expression of TrkB was significantly down-regulated in the blood of MDD patients, but not in SCZ patients. However, there was no significant correlation between BDNF concentrations and TrkB mRNA levels. Taken together, our results revealed differential changes of BDNF-TrkB signaling in MDD and SCZ patients, therefore contributed to a better understanding of MDD and SCZ pathophysiology.

Promoting Osteogenic Differentiation of Human Adipose-Derived Stem Cells by Altering the Expression of Exosomal miRNA

Human adipose-derived stem cells (ADSCs) can release exosomes; however, their specific functions remain elusive. In this study, we verified that exosomes derived from osteogenically differentiated ADSCs can promote osteogenic differentiation of ADSCs. Furthermore, in order to investigate the importance of exosomal microRNAs (miRNAs) in osteogenic differentiation of ADSCs, we used microarray assays to analyze the expression profiles of exosomal miRNAs derived from undifferentiated as well as osteogenically differentiated ADSCs; 201 miRNAs were upregulated and 33 miRNAs were downregulated between the two types of exosomes. Additionally, bioinformatic analyses, which included gene ontology analyses, pathway analysis, and miRNA-mRNA-network investigations, were performed. The results of these analyses revealed that the differentially expressed exosomal miRNAs participate in multiple biological processes, such as gene expression, synthesis of biomolecules, cell development, differentiation, and signal transduction, among others. Moreover, we found that these differentially expressed exosomal miRNAs connect osteogenic differentiation to processes such as axon guidance, MAPK signaling, and Wnt signaling. To the best of our knowledge, this is the first study to identify and characterize exosomal miRNAs derived from osteogenically differentiated ADSCs. This study confirms that alterations in the expression of exosomal miRNAs can promote osteogenic differentiation of ADSCs, which also provides the foundation for further research on the regulatory functions of exosomal miRNAs in the context of ADSC osteogenesis.