Circular RNAs in early brain development and their influence and clinical significance in neuropsychiatric disorders

Circular RNAs perspective: exploring the direction of immunotherapy for colorectal cancer

Circular RNAs (circRNAs) are multifaceted molecules that play a pivotal role in regulating gene expression at both transcriptional and post-transcriptional levels. Their expression is highly tissue-specific and developmentally regulated, making them critical players in various physiological processes and diseases, particularly cancer. In colorectal cancer, circRNAs exhibit significantly dysregulated expression patterns and profoundly influence disease progression through diverse molecular mechanisms. Unraveling the complex roles of circRNAs in modulating colorectal cancer immunotherapy outcomes highlights their potential as both promising biomarkers and therapeutic targets. Moving forward, advancements in circRNA-based therapeutic strategies and delivery systems are poised to transform precision medicine, enabling early colorectal cancer diagnosis and improving patient prognosis.

Proteomics of neuropsychiatric disorders

The pathogenesis of neuropsychiatric disorders (NDs) remains largely unclear, hence there is a lack of objective and reliable biomarkers. Proteomics, as a powerful tool for disease biomarkers research, has been largely ignored in the field of NDs. This review summarizes recent research on the application of mass spectrometry-based proteomics in NDs. Proteins associated with NDs have been identified in various sample sources, including blood, urine, saliva, tear, cerebrospinal fluid, and brain tissue. These studies have preliminarily demonstrated the potential of proteomics in NDs and require comprehensive validation in multi-center, large-scale clinical cohorts. We also discuss the challenges and prospects of proteomics in the research of early diagnostic biomarkers for NDs. These findings may provide a foundation for developing proteomic-based diagnostics and advancing precision medicine in NDs.

Non-coding RNA alterations in occlusal disharmony-induced anxiety-like behaviour

BACKGROUND

Occlusal disharmony (OD) may induce anxiety-like behaviours; however, the underlying mechanism remains unclear. Herein, we explored the expression profiles of non-coding RNAs (ncRNAs), along with their biological function and regulatory network, in anxiety-like behaviour induced by OD.

MATERIALS AND METHODS

Occlusal disharmony was produced by anterior crossbite of C57BL/6 mice. Behavioural tests, corticosterone (CORT) and serotonin (5-HT) levels were used to measure anxiety. In addition, RNA sequencing was used to screen all differentially expressed (DE) ncRNAs. Moreover, the RNA-binding proteins interacting with ncRNAs were predicted by the ENCORI database and confirmed using western blots.

RESULTS

The significant differences in behavioural tests and CORT suggested the successful induction of anxiety-like behaviour by OD. In OD mice, ncRNAs were significantly dysregulated. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses suggested that the DE ncRNAs were enriched in anxiety-related pathways. CircRNA10039 was upregulated, and PTBP1 was predicted to interact with circRNA10039. In addition, KEGG pathway analysis showed that PTBP1 may be associated with messenger RNA biogenesis and spliceosomes.

CONCLUSION

OD induced by anterior crossbite can lead to the anxiety-like behaviours. During this process, ncRNA also changes. CircRNA10039 and PTBP1 may play a role in OD-induced anxiety-like behaviours.

Advances in biosensors for major depressive disorder diagnostic biomarkers

Depression is one of the most common mental disorders and is mainly characterized by low mood or lack of interest and pleasure. It can be accompanied by varying degrees of cognitive and behavioral changes and may lead to suicide risk in severe cases. Due to the subjectivity of diagnostic methods and the complexity of patients' conditions, the diagnosis of major depressive disorder (MDD) has always been a difficult problem in psychiatry. With the discovery of more diagnostic biomarkers associated with MDD in recent years, especially emerging non-coding RNAs (ncRNAs), it is possible to quantify the condition of patients with mental illness based on biomarker levels. Point-of-care biosensors have emerged due to their advantages of convenient sampling, rapid detection, miniaturization, and portability. After summarizing the pathogenesis of MDD, representative biomarkers, including proteins, hormones, and RNAs, are discussed. Furthermore, we analyzed recent advances in biosensors for detecting various types of biomarkers of MDD, highlighting representative electrochemical sensors. Future trends in terms of new biomarkers, new sample processing methods, and new detection modalities are expected to provide a complete reference for psychiatrists and biomedical engineers.

Potential therapeutic and diagnostic approaches of exosomes in multiple sclerosis pathophysiology

Exosomes are bilayer lipid vesicles that are released by cells and contain proteins, nucleic acids, and lipids. They can be internalized by other cells, inducing inflammatory responses and instigating toxicities in the recipient cells. Exosomes can also serve as therapeutic vehicles by transporting protective cargo to maintain homeostasis. Multiple studies have shown that exosomes can initiate and participate in the regulation of neuroinflammation, improve neurogenesis, and are closely related to the pathogenesis of central nervous system (CNS) diseases, including multiple sclerosis (MS). Exosomes can be secreted by both neurons and glial cells in the CNS, and their contents change with disease occurrence. Due to their ability to penetrate the blood-brain barrier and their stability in peripheral fluids, exosomes are attractive biomarkers of CNS diseases. In recent years, exosomes have emerged as potential therapeutic agents for CNS diseases, including MS. However, the molecular pathways in the pathogenesis of MS are still unknown, and further research is needed to fully understand the role of exosomes in the occurrence or improvement of MS disease. Thereby, in this review, we intend to provide a more complete understanding of the pathways in which exosomes are involved and affect the occurrence or improvement of MS disease.

A Review of the Use of Extracellular Vesicles in the Treatment of Neonatal Diseases: Current State and Problems with Translation to the Clinic

Neonatal disorders, particularly those resulting from prematurity, pose a major challenge in health care and have a significant impact on infant mortality and long-term child health. The limitations of current therapeutic strategies emphasize the need for innovative treatments. New cell-free technologies utilizing extracellular vesicles (EVs) offer a compelling opportunity for neonatal therapy by harnessing the inherent regenerative capabilities of EVs. These nanoscale particles, secreted by a variety of organisms including animals, bacteria, fungi and plants, contain a repertoire of bioactive molecules with therapeutic potential. This review aims to provide a comprehensive assessment of the therapeutic effects of EVs and mechanistic insights into EVs from stem cells, biological fluids and non-animal sources, with a focus on common neonatal conditions such as hypoxic-ischemic encephalopathy, respiratory distress syndrome, bronchopulmonary dysplasia and necrotizing enterocolitis. This review summarizes evidence for the therapeutic potential of EVs, analyzes evidence of their mechanisms of action and discusses the challenges associated with the implementation of EV-based therapies in neonatal clinical practice.

Transcriptome sequencing of circular RNA reveals the involvement of hsa-SCMH1_0001 in the pathogenesis of Parkinson's disease

BACKGROUND

Parkinson's disease (PD) is the second most common neurodegenerative disease. Exosomes are endosome-derived extracellular vesicles that can take part in intercellular communication. Circular RNAs (circRNAs) are noncoding RNAs characterized by covalently closed-loop structures, which perform a crucial function in many diseases.

AIM

To clarify the expression and function of exosomal circRNSs of PD patients and look for circRNAs that might be related to the pathogenesis of PD.

MATERIALS AND METHODS

We examined circRNA and mRNA expression profiles in peripheral exosomes from PD patients (n = 23) and healthy controls (n = 15) using next-generation sequencing (NGS) technology, functional annotation, and quantitative polymerase chain reaction. Correlation analysis was performed between the expression levels of the circRNAs and the clinical characteristics of PD patients. The binding miRNAs and target genes were predicted using TargetScanHuman, miRDB, and miRTarBase. The predicted target genes were compared with the differentially expressed mRNAs in sequencing results.

RESULTS

According to the NGS, 62 upregulated and 37 downregulated circRNAs in the PD group were screened out. Correlation analysis revealed that hsa-SCMH1_0001 has strong clinical relevance. We identified 17 potential binding miRNAs of hsa-SCMH1_0001 with 149 potential target genes. ARID1A and C1orf115 belong to the intersection of the predicted target genes and the differentially expressed mRNAs obtained by sequencing.

CONCLUSION

This study suggested that hsa-SCMH1_0001 and its target genes ARID1A and C1orf115 are downregulated in PD patients and may be involved in the occurrence of PD.

Extracellular vesicle approach to major psychiatric disorders

Over the last few years, extracellular vesicles (EVs) have received increasing attention as potential non-invasive diagnostic and therapeutic biomarkers for various diseases. The interest in EVs is related to their structure and content, as well as to their changing cargo in response to different stimuli. One of the potential areas of use of EVs as biomarkers is the central nervous system (CNS), in particular the brain, because EVs can cross the blood-brain barrier, exist also in peripheral tissues and have a diverse cargo. Thus, they may represent "liquid biopsies" of the CNS that can reflect brain pathophysiology without the need for invasive surgical procedures. Overall, few studies to date have examined EVs in neuropsychiatric disorders, and the present evidence appears to lack reproducibility. This situation might be due to a variety of technical obstacles related to working with EVs, such as the use of different isolation strategies, which results in non-uniform vesicular and molecular outputs. Multi-omics approaches and improvements in the standardization of isolation procedures will allow highly pure EV fractions to be obtained in which the molecular cargo, particularly microRNAs and proteins, can be identified and accurately quantified. Eventually, these advances will enable researchers to decipher disease-relevant molecular signatures of the brain-derived EVs involved in synaptic plasticity, neuronal development, neuro-immune communication, and other related pathways. This narrative review summarizes the findings of studies on EVs in major psychiatric disorders, particularly in the field of biomarkers, and discusses the respective therapeutic potential of EVs.

Exosome and exosomal contents in schizophrenia

Schizophrenia (SCZ) is a severe mental disorder that affects approximately 1% general population worldwide and poses a considerable burden to society. Despite decades of research, its etiology remains unclear, and diagnosis remains challenging due to its heterogeneous symptoms. Exosomes play a crucial role in intercellular communication, and their contents, including nucleotides, proteins and metabolites, have been linked to various diseases. Recent studies have implicated exosome abnormalities in the pathogenesis of schizophrenia. In this review, we discuss the current understanding of the relationship between exosomes and schizophrenia, focusing on the role of exosomal contents in this disease. We summarize recent findings and provide insights into the potential use of exosomes as biomarkers for the diagnosis and treatment of schizophrenia.

Exosomes in brain diseases: Pathogenesis and therapeutic targets

Exosomes are extracellular vesicles with diameters of about 100 nm that are naturally secreted by cells into body fluids. They are derived from endosomes and are wrapped in lipid membranes. Exosomes are involved in intracellular metabolism and intercellular communication. They contain nucleic acids, proteins, lipids, and metabolites from the cell microenvironment and cytoplasm. The contents of exosomes can reflect their cells' origin and allow the observation of tissue changes and cell states under disease conditions. Naturally derived exosomes have specific biomolecules that act as the "fingerprint" of the parent cells, and the contents changed under pathological conditions can be used as biomarkers for disease diagnosis. Exosomes have low immunogenicity, are small in size, and can cross the blood-brain barrier. These characteristics make exosomes unique as engineering carriers. They can incorporate therapeutic drugs and achieve targeted drug delivery. Exosomes as carriers for targeted disease therapy are still in their infancy, but exosome engineering provides a new perspective for cell-free disease therapy. This review discussed exosomes and their relationship with the occurrence and treatment of some neuropsychiatric diseases. In addition, future applications of exosomes in the diagnosis and treatment of neuropsychiatric disorders were evaluated in this review.

Therapeutic and Diagnostic Potential of Exosomes as Drug Delivery Systems in Brain Cancer

Cancer is designated as one of the principal causes of mortality universally. Among different types of cancer, brain cancer remains the most challenging one due to its aggressiveness, the ineffective permeation ability of drugs through the blood-brain barrier (BBB), and drug resistance. To overcome the aforementioned issues in fighting brain cancer, there is an imperative need for designing novel therapeutic approaches. Exosomes have been proposed as prospective "Trojan horse" nanocarriers of anticancer theranostics owing to their biocompatibility, increased stability, permeability, negligible immunogenicity, prolonged circulation time, and high loading capacity. This review provides a comprehensive discussion on the biological properties, physicochemical characteristics, isolation methods, biogenesis and internalization of exosomes, while it emphasizes their therapeutic and diagnostic potential as drug vehicle systems in brain cancer, highlighting recent advances in the research field. A comparison of the biological activity and therapeutic effectiveness of several exosome-encapsulated cargo including drugs and biomacromolecules underlines their great supremacy over the non-exosomal encapsulated cargo in the delivery, accumulation, and biological potency. Various studies on cell lines and animals give prominence to exosome-based nanoparticles (NPs) as a promising and alternative approach in the management of brain cancer.

Plant-Derived Exosome-like Nanoparticles for Biomedical Applications and Regenerative Therapy

Plant-derived exosome-like nanoparticles (PDENs) comprise various bioactive biomolecules. As an alternative cell-free therapeutic approach, they have the potential to deliver nano-bioactive compounds to the human body, and thus lead to various anti-inflammatory, antioxidant, and anti-tumor benefits. Moreover, it is known that Indonesia is one of the herbal centers of the world, with an abundance of unexplored sources of PDENs. This encouraged further research in biomedical science to develop natural richness in plants as a source for human welfare. This study aims to verify the potential of PDENs for biomedical purposes, especially for regenerative therapy applications, by collecting and analyzing data from the latest relevant research and developments.

Circular RNAs in extracellular vesicles: Promising candidate biomarkers for schizophrenia

As one of common and severe mental illnesses, schizophrenia is difficult to be diagnosed exactly. Both its pathogenesis and the causes of its development are still uncertain because of its etiology complexity. At present, the diagnosis of schizophrenia is mainly based on the patient's symptoms and signs, lacking reliable biomarkers that can be used for diagnosis. Circular RNAs in extracellular vesicles (EV circRNAs) can be used as promising candidate biomarkers for schizophrenia and other diseases, for they are not only high stability and disease specificity, but also are rich in contents and easy to be detected. The review is to focus on the research progress of the correlation between circRNAs and schizophrenia, and then to explores the possibility of EV circRNAs as new biomarkers for the schizophrenia diagnosis.

Role of Exosomes in Pharyngucutaneous Fistula After Total Laryngectomy

Pharyngocutaneous fistula is the most common complication after total laryngectomy and is difficult to heal. Although conservative treatment and surgical repair are effective, they often take longer and additional trips to the operating room, which undoubtedly increases the financial burden on patients. Especially in combination with diseases such as diabetes and hypertension, which affect the efficacy of surgery. Adding growth factors into the repair material can promote fibroblast proliferation, angiogenesis, and accelerate wound healing. A substantial number of studies have shown that a type of nanoscale extracellular vesicle, called exosomes, facilitates organization repair by promoting blood vessel production, protein polysaccharides, and collagen deposition, thereby representing a new type of cellular therapy. At present, there is little research on the application of exosomes in pharyngocutaneous fistula regeneration after total laryngectomy. In this review, we summarize the biological characteristics of exosomes and their application in biomedical science, and highlight their application prospects in pharyngocutaneous fistula regeneration after total laryngectomy.

Male mice exposed to chronic intermittent ethanol exposure exhibit significant upregulation or downregulation of circular RNAs

B a ckground: Circular RNAs (circRNAs) have been crucially implicated in various diseases, however, their involvement in chronic intermittent ethanol (CIE) exposure remains unclear.O bjective: The present study was conducted to evaluate the circular RNA expression alteration in brain samples and to identify the molecular mechanisms underlying chronic intermittent ethanol exposure.M ethods: Male C57BL/6J mice (10 for each group) were given 4 weeks of chronic intermittent ethanol exposure. Whole brain samples were collected for high-throughput sequencing and circRNA bioinformatic analysis. Real-time quantitative PCR (RI-qPCR) and agarose electrophoresis were used to validate the differentially expressed circRNAs. Gene Ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes pathway (KEGG) analysis were performed. A p level < 0.05 was considered statistically significant.R esults: Compared with the control group and baseline values, the CIE group showed a significant increase in ethanol intake. High-throughput sequencing revealed 399 significantly different circRNAs in CIE mice, including 150 up-regulated circRNAs and 249 down-regulated circRNAs. GO analysis showed that the most significantly enriched term for biological process, cellular component, and molecular function were GO:0050885, GO:0016020 and GO:0005515, respectively. The most enriched pathways in KEGG analysis were GABAergic synapse (mmu04727), followed by retrograde endocannabinoid (eCB) signaling (mmu04723) and morphine addiction (mmu05032). Among the circRNAs, RT-qPCR confirmed 14 upregulated and 13 downregulated circRNAs in the brain tissues with 9 upregulated and 10 downregulated circRNAs being observed in blood samples.C onclusions: Our study suggests that chronic ethanol exposure upregulates or downregulates circRNAs in the brain, which, in turn, could alter neurotransmitter release and signal transduction.

Identification of potential key circular RNAs related to cognitive impairment after chronic constriction injury of the sciatic nerve

Chronic neuropathic pain is commonly accompanied by cognitive impairment. However, the underlying mechanism in the occurrence of cognitive deficits under constant nociceptive irritation remains elusive. Herein, we established a chronic neuropathic pain model by chronic constriction injury (CCI) of the unilateral sciatic nerve in rats. Behavioral tests indicated that CCI rats with long-term nociceptive threshold decline developed significant dysfunction of working memory and recognitive memory starting at 14 days and lasting for at least 21 days. Afterward, circRNA expression profiles in the hippocampus of CCI and sham rats were analyzed via high-throughput sequencing to explore the potential key factors associated with cognitive impairment induced by ongoing nociception, which showed 76 differentially expressed circRNAs, 39 upregulated and 37 downregulated, in the CCI group. These differentially expressed circRNA host genes were validated to be primarily associated with inflammation and apoptotic signaling pathways according to GO/KEGG analysis and the circRNA-miRNA-mRNA network, which was also confirmed through the analysis of neuroinflammation and neuronal apoptosis. Consequently, we assumed that enhanced neuroinflammation and neuronal apoptosis might act as potential regulators of cognitive impairment induced by chronic neuropathic pain. The identification of the regulatory mechanism would provide promising clinical biomarkers or therapeutic targets in the diagnostic prediction and intervention treatment of memory deficits under neuropathic pain conditions.

Usability evaluation of circRNA identification tools: Development of a heuristic-based framework and analysis

BACKGROUND AND OBJECTIVE

Circular RNAs (circRNAs) are endogenous molecules of non-coding RNA that form a covalently closed loop at the 3' and 5' ends. Recently, the role of these molecules in the regulation of gene expression and their involvement in several human pathologies has gained notoriety. The identification of circRNAs is highly dependent on computational methods for analyzing RNA sequencing data. However, bioinformatics software is known to be problematic in terms of usability. Evidence points out that tools for identifying circRNAs can have such problems, negatively impacting researchers in this field. Here we present a heuristic-based framework for evaluating the usability of command-line circRNA identification software.

METHODS

We used heuristics evaluation to comprehensively identify the usability issues in a sample of circRNA identification tools.

RESULTS

We identified 46 usability issues presented individually in four tools. Most of the issues had cosmetic or minor severity. These are unlikely to challenge experienced users but may cause inconvenience for novice users. We also identified severe issues with the potential to harm users regardless of their experience. The areas most affected were the documentation and the installability of the tools.

CONCLUSIONS

With the proposed framework, we formally describe, for the first time, the usability problems that can affect users in this area of circRNA research. We hope that our framework can help researchers evaluate their software's usability during development.

Circular RNA: A novel and potential regulator in pathophysiology of schizophrenia

Circular RNAs (CircRNAs) are a sub-class of non-coding RNA, which are covalently closed at the ends through a non-canonical process called, backsplicing from the precursor linear RNAs. These molecules are involved in several biological phenomena including regulation of gene expression, synaptic plasticity, and cognition. Several studies have shown that circRNA are present abundantly inside the mammalian brain and they are believed to be associated with the development of neurons and neuronal functions. It is also evident that alterations in intracellular and extracellular levels of circRNAs are linked with various neurological and neuropsychiatric disorders including schizophrenia (SZ). Detailed studies of circRNAs are required to decode the molecular mechanism behind the onset of SZ and the related biological activities during disease progression. This can help unravel their role in this neurobehavioral disorder and develop effective therapeutics against the disease. The present review mainly focuses on the expression and activities of the circRNAs in the post-mortem brain, peripheral blood, and exosomes. It also gives an insight into the role of circRNA interaction with RNA binding proteins (RBPs) and nucleotide modification and their therapeutic potential in the context of schizophrenia.

Identification of a circRNA-mediated comprehensive ceRNA network in spinal cord injury pathogenesis

RNAs are closely associated with human diseases; however, immune-related genes (IRGs) and their potential regulatory networks in relation to spinal cord injury (SCI) are still poorly understood. Here, we investigated the key IRGs as well as the competing endogenous RNA (ceRNA) mechanisms that are associated with SCI pathogenesis based on microarray datasets and the use of a rat SCI model. Specifically, four independent SCI microarray datasets from Gene Expression Omnibus (GEO) database were analyzed and, thereafter, differentially expressed IRGs were annotated via Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Furthermore, based on the GEO datasets, differentially expressed RNAs (DERNAs), including DEcircRNAs, DEmiRNAs, and DEmRNAs were identified and interactions between them were also predicted using online databases, and to construct a circular RNA (circRNA) mediated ceRNA network, candidate RNAs were also identified. Furthermore, the support vector machine (SVM) and least absolute shrinkage and selection operator (LASSO) methods were used for the identification of critical DERNAs, while differential gene expression was validated using the GSE20907 dataset. Our results were as follows. In the SCI microarray datasets, 32, 58, and 74 DEIRGs, DEcircRNAs, and DEmiRNAs were identified, respectively. In addition, GO and KEGG analyses showed that the DEIRGs were primarily enriched in neutrophil-mediated immunity and nuclear factor-kappa B (NF-κB) and hypoxia-inducible factor-1 (HIF-1) signaling pathways, and based on LASSO and SVM screening, PLXNB2 was identified as a DEIRG, while hsa_circ_0026646 was identified as the key circRNA, showing a higher SCI expression. Furthermore, our results proved that PLXNB2 and hsa_circ_0026646 were upregulated in SCI, whereas miR-331-3p was downregulated, and, interestingly, similar expression profiles were confirmed using the rat SCI model. Furthermore, fluorescent reporter assay indicated that both hsa_circ_0026646 and PLXNB2 have miR-331-3p target sites, and the ceRNA hypothesis suggested the dysregulation of hsa_circ_0026646, miR-331-3p, and PLXNB2 in SCI. Thus, our results suggested that in SCI pathogenesis, hsa_circ_0026646 correlates with PLXNB2 by targeting miR-331-3p.

A new perspective on depression and neuroinflammation: Non-coding RNA

The high incidence and relapse rate of depression, as well comorbidity with other diseases, has made depression one of the primary causes of years of life lived with disability. Moreover, the unknown biological mechanism of depression has made treatment difficult. Neuroinflammation is important in the pathogenesis of depression. Neuroinflammation may affect depression by regulating the production of immune factors, immune cell activation, neuron generation, synaptic plasticity, and neurotransmission. Non-coding RNAs (ncRNAs) may be a breakthrough link between depression and neuroinflammation, as ncRNAs participate in these biological changes. We summarize the functions and mechanisms of ncRNAs in neuroinflammation and depression, and predict ncRNAs that may regulate the occurrence and progression of depression through neuritis. These findings not only broaden our understanding of the genetic regulation of depression and neuroinflammation but also provide a new perspective of the underlying mechanism and aid in the design of novel prevention, diagnosis, and treatment strategies.

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.

Potential Clinical Applications of Exosomal Circular RNAs: More than Diagnosis

Exosomes are small vesicles derived from cells used as cell-to-cell communication goods in numerous diseases including tumorigenesis, neurological diseases, cardiovascular diseases and other diseases. Circular RNAs (circRNAs) are an innovative constituent of non-coding endogenous RNAs generated through backsplicing, catalyzed by RNA polymerase Ⅱ. These non-coding RNAs have been suggested to control gene expression through miRNA sponging, RNA-binding protein regulation and translational capabilities. Genome-wide RNA sequence analyses observed that circRNAs were stably improved in exosomes in association to parental cells. Little attention has been dedicated to exosomal circRNAs (exo-circRNAs). However, research has demonstrated that exo-circRNAs may have important regulatory functions because of their stability in cells and within exosomes. If well understood, the precise roles and mechanisms of exo-circRNAs might surge the impending clinical applications of these molecules as markers in the identification, prediction and treatment of various diseases. In this review, we outline recent findings regarding exo-circRNAs which includes their functions and highlights their potential applications and therapeutic targets in human diseases.

[Role and mechanism of circular RNA in brain injury induced by inflammation in preterm mice: a preliminary study]

OBJECTIVE

To determine the association of circular RNA (circRNA) and circRNA-microRNA (miRNA) network regulation with brain injury induced by inflammation in preterm mice.

METHODS

Pregnant mice were treated with intraperitoneally injected lipopolysaccharide to establish a preterm mouse model of brain injury induced by inflammation (inflammation preterm group with 3 mice). Preterm mice born to normal pregnant mice by cesarean section were selected as controls (non-inflammation preterm group with 3 mice). The gene microarray technique was used to screen out the circRNAs associated with brain injury in preterm mice. The miRNA target prediction software was used to predict the binding sites between circRNAs and miRNAs and analyze the regulatory mechanism.

RESULTS

A total of 365 differentially expressed circRNAs were screened out between the inflammation preterm and non-inflammation preterm groups (fold change > 1.5, P < 0.05), among which there were 206 upregulated circRNAs and 159 downregulated circRNAs. Further analysis of the circRNAs with a fold change of > 4 showed that these circRNAs could bind to miRNAs and regulate their activity, thereby regulating the expression of the genes associated with the nervous system.

CONCLUSIONS

Inflammation induces a significant change in the expression profile of circRNAs in the brain tissue of mice, and the change in the expression of circRNAs plays an important role in brain injury induced by inflammation and subsequent brain development in preterm mice.

Expression and function of circular RNAs in the mammalian brain

Mammalian brain presents extraordinary complexity reflected in the structure, function, and dynamic changes in the biological and physiological processes of development, maturity, and aging. Recent transcriptomic profiles from the brain tissues of distinct species have described a novel class of transcripts with a covalently closed-loop structure, called circular RNAs (circRNAs), which are produced by alternative back-splicing and derived from genes associated with synaptogenesis and neural activities. Brain is a tightly regulated and largely unexplored organ where circRNAs are highly enriched and expressed in the cell type-, spatiotemporal-specific, sex-biased, and age-related manner. Although the biological functions of most of the circRNAs in the brain remain elusive, increased evidence suggests that dynamic changes in circRNA expression are critical for brain function and the maintenance of physiological homeostasis in the brain. Here, we review the latest immense progresses in the understanding of circRNA expression and function in the mammalian brain. We also discuss possibly biological functions of circRNAs in the brain, which may provide new sights of understanding brain development and aging, as well as the pathogenesis of mental diseases.

Potential clinical value of circular RNAs as peripheral biomarkers for the diagnosis and treatment of major depressive disorder

Background

circular RNAs (circRNAs) are expressed abundantly in the brain and are implicated in the pathophysiology of neuropsychiatric disease. However, the potential clinical value of circRNAs in major depressive disorder (MDD) remains unclear.

Methods

RNA sequencing was conducted in whole-blood samples in a discovery set (7 highly homogeneous MDD patients and 7 matched healthy controls [HCs]). The differential expression of circRNAs was verified in an independent validation set. The interventional study was conducted to assess the potential effect of the antidepressive treatment on the circRNA expression.

Findings

in the validation set, compared with 52 HCs, significantly decreased circFKBP8 levels (Diff: -0.24; [95% CI -0.39 ~ -0.09]) and significantly elevated circMBNL1 levels (Diff: 0.37; [95% CI 0.09 ~ 0.64]) were observed in 53 MDD patients. The expression of circMBNL1 was negatively correlated with 24-item Hamilton Depression Scale (HAMD-24) scores in 53 MDD patients. A mediation model indicated that circMBNL1 affected HAMD-24 scores through a mediator, serum brain-derived neurotrophic factor. In 53 MDD patients, the amplitude of low-frequency fluctuations in the right orbital part middle frontal gyrus was positively correlated with circFKBP8 and circMBNL1 expression. Furthermore, the interventional study of 53 MDD patients demonstrated that antidepressive treatment partly increased circFKBP8 expression and the change in expression of circFKBP8 was predictive of further reduced HAMD-24 scores.

Interpretation

whole-blood circFKBP8 and circMBNL1 may be potential biomarkers for the diagnosis of MDD, respectively, and circFKBP8 may show great potential for the antidepressive treatment.

Protective effects of baicalin on caerulein-induced AR42J pancreatic acinar cells by attenuating oxidative stress through miR-136-5p downregulation

Baicalin, the main active component of Scutellaria baicalensis, has antioxidant and anti-apoptotic effects and is used to treat acute pancreatitis; however, its specific mechanism is unclear. This study aims to determine the protective effect and underlying mechanism of baicalin on AR42J pancreatic acinar cell injury. AR42J acinar cells (caerulein, 10 nmol/L) were induced in vitro to establish a cell model for acute pancreatitis. Cell relative survival was measured by thiazolyl blue tetrazolium bromide, and cell apoptosis and death were examined by flow cytometry. The expression levels of superoxide dismutase1 (SOD1), Bax, survivin, Bcl-2, caspase-3, and caspase-7 proteins were analyzed by Western blot, and those of SOD1 mRNA and miR-136-5p were determined by RT-PCR. The activities of GSH, SOD1, ROS, and MDA were also investigated. Compared with those of the caerulein group, the relative survival rate and activity of AR42J pancreatic acinar cells with different baicalin concentrations were significantly increased (p < 0.05), and the supernatant amylase level was markedly decreased (p < 0.05). In addition, the ROS and MDA activities and mir-136-5p expression were significantly decreased, and the GSH activities and SOD1 gene and protein expression levels were markedly increased (p < 0.05). These results suggest that baicalin reduced the caerulein-induced death of AR42J acinar cells and alleviated the caerulein-induced injury in pancreatic acinar cells by inhibiting oxidative stress. The mechanism may be related to the decreased expression of Mir-136-5p and the increased expression of SOD1 gene and protein.

News about the Role of Fluid and Imaging Biomarkers in Neurodegenerative Diseases

Biomarkers are molecules that are variable in their origin, nature, and mechanism of action; they are of great relevance in biology and also in medicine because of their specific connection with a single or several diseases. Biomarkers are of two types, which in some cases are operative with each other. Fluid biomarkers, started around 2000, are generated in fluid from specific proteins/peptides and miRNAs accumulated within two extracellular fluids, either the central spinal fluid or blood plasma. The switch of these proteins/peptides and miRNAs, from free to segregated within extracellular vesicles, has induced certain advantages including higher levels within fluids and lower operative expenses. Imaging biomarkers, started around 2004, are identified in vivo upon their binding by radiolabeled molecules subsequently revealed in the brain by positron emission tomography and/or other imaging techniques. A positive point for the latter approach is the quantitation of results, but expenses are much higher. At present, both types of biomarker are being extensively employed to study Alzheimer’s and other neurodegenerative diseases, investigated from the presymptomatic to mature stages. In conclusion, biomarkers have revolutionized scientific and medical research and practice. Diagnosis, which is often inadequate when based on medical criteria only, has been recently improved by the multiplicity and specificity of biomarkers. Analogous results have been obtained for prognosis. In contrast, improvement of therapy has been limited or fully absent, especially for Alzheimer’s in which progress has been inadequate. An urgent need at hand is therefore the progress of a new drug trial design together with patient management in clinical practice.

A Narrative Review of Circular RNAs in Brain Development and Diseases of Preterm Infants

Circular RNAs (circRNAs) generated by back-splicing are the vital class of non-coding RNAs (ncRNAs). Circular RNAs are highly abundant and stable in eukaryotes, and many of them are evolutionarily conserved. They are blessed with higher expression in mammalian brains and could take part in the regulation of physiological and pathophysiological processes. In addition, premature birth is important in neurodevelopmental diseases. Brain damage in preterm infants may represent the main cause of long-term neurodevelopmental disorders in surviving babies. Until recently, more and more researches have been evidenced that circRNAs are involved in the pathogenesis of encephalopathy of premature. We aim at explaining neuroinflammation promoting the brain damage. In this review, we summarize the current findings of circRNAs properties, expression, and functions, as well as their significances in the neurodevelopmental impairments, white matter damage (WMD) and hypoxic-ischemic encephalopathy (HIE). So we think that circRNAs have a direct impact on neurodevelopment and brain injury, and will be a powerful tool in the repair of the injured immature brain. Even though their exact roles and mechanisms of gene regulation remain elusive, circRNAs have potential applications as diagnostic biomarkers for brain damage and the target for neuroprotective intervention.

The differential expression and potential roles of circular RNAs in children with anti-NMDA receptor encephalitis

To explore the role of circular RNAs (circRNAs) in pediatric anti-N-methyl-d-aspartate (NMDA) receptor encephalitis, we assessed the profiles of circRNAs and mRNAs in blood leukocytes from anti-NMDA receptor encephalitis patients and healthy controls using microarray analysis. 1196 circRNAs and 719 mRNAs (change ≥2, p < .05) were dysregulated in anti-NMDA receptor encephalitis patients, relative to healthy controls, based on microarray data. Further bioinformatic analysis demonstrated that the host genes of dysregulated circRNAs are primarily associated with receptor internalization. In conclusion, circRNAs may be implicated in the pathogenesis of pediatric anti-NMDA receptor encephalitis.

AVPR1A main effect and OXTR-by-environment interplay in individual differences in depression level

Background

Multiple studies of depression indicated a significant role of gene-by-environment interactions; however, they are mainly limited to the examination of modulating effect of recent stressful life events. Other environmental factors occurring at different stages of ante- and postnatal development may affect the association between multiple genes and depression. The study aimed to analyze the main and haplotype-based effect of serotonergic system and HPA-axis gene polymorphisms on depression and to detect gene-by-environment interaction models explaining individual variance in depression in mentally healthy young adults from Russia.

Methods

Depression score was assessed using Beck Depression Inventory (BDI) in 623 healthy individuals (81% women; 17-25 years) of Caucasian origin (Russians, Tatars, Udmurts) from Russia. The main- and gene-based effects of 12 SNPs in SLC6A4 (5-HTTLPR, rs1042173), HTR2A (rs7322347), OXTR (rs7632287, rs2254298, rs13316193, rs53576, rs2228485, rs237911), AVPR1A (rs3803107, rs1042615), and AVPR1B (rs33911258) genes, and gene-by-environment interactions were tested with linear regression models (PLINK v.1.9) adjusted for multiple comparisons.

Results

We observed ethnicity-specific main effect of the AVPR1A rs3803107 (P = 0.003; P_FDR = 0.047) and gene-based effect of the OXTR gene (Р = 0.005; P_perm = 0.034) on BDI-measured depression, and modifying effect of paternal care on OXTR rs53576 (P = 0.004; P_FDR = 0.012) and birth order on OXTR rs237911 (P = 0.006; P_FDR = 0.018) association with depression level.

Limitations

A hypothesis driven candidate gene approach, which examined a limited number of genetic variants in a moderately large sample, was used.

Conclusions

Our preliminary findings indicate that familial environment may play a permissive role modulating the manifestation of OXTR-based depression variance in mentally healthy subjects.

Exosome: A Review of Its Classification, Isolation Techniques, Storage, Diagnostic and Targeted Therapy Applications

Exosomes are nano-sized small extracellular vesicles secreted by cells, carrying nucleic acids, proteins, lipids and other bioactive substances to play a role in the body's physiological and pathological processes. Compared to synthetic carriers such as liposomes and nanoparticles, the endogeneity and heterogeneity of exosomes give them extensive and unique advantages in the field of disease diagnosis and treatment. However, the storage stability, low yield, low purity, and weak targeting of exosomes limit its clinical application. For this reason, further exploration is needed to optimize the above problems and facilitate future functional studies of exosomes. In this paper, the origin, classification, preparation and characterization, storage stability and applications of exosome delivery system are summarized and discussed by searching a large number of literatures.

CircPSMC3 alleviates the symptoms of PCOS by sponging miR-296-3p and regulating PTEN expression

Polycystic ovary syndrome (PCOS), the most common female endocrine disease that causes anovulatory infertility, still lacks promising strategy for the accurate diagnosis and effective therapeutics of PCOS attributed to its unclear aetiology. In this study, we determined the abnormal reduction in circPSMC3 expression by comparing the ovarian tissue samples of PCOS patients and normal individuals. The symptom relief caused by up-regulation of circPSMC3 in PCOS model mice suggested the potential for further study. In vitro functional experiments confirmed that circPSMC3 can inhibit cell proliferation and promote apoptosis by blocking the cell cycle in human-like granular tumour cell lines. Mechanism study revealed that circPSMC3 may play its role through sponging miR-296-3p to regulate PTEN expression. Collectively, we preliminarily characterized the role and possible insights of circPSMC3/miR-296-3p/PTEN axis in the proliferation and apoptosis of KGN cells. We hope that this work provides some original and valuable information for the research of circRNAs in PCOS, not only to better understand the pathogenesis but also to help provide new clues for seeking for the future therapeutic target of PCOS.

A Two-Dimensional Affinity Capture and Separation Mini-Platform for the Isolation, Enrichment, and Quantification of Biomarkers and Its Potential Use for Liquid Biopsy

Biomarker detection for disease diagnosis, prognosis, and therapeutic response is becoming increasingly reliable and accessible. Particularly, the identification of circulating cell-free chemical and biochemical substances, cellular and subcellular entities, and extracellular vesicles has demonstrated promising applications in understanding the physiologic and pathologic conditions of an individual. Traditionally, tissue biopsy has been the gold standard for the diagnosis of many diseases, especially cancer. More recently, liquid biopsy for biomarker detection has emerged as a non-invasive or minimally invasive and less costly method for diagnosis of both cancerous and non-cancerous diseases, while also offering information on the progression or improvement of disease. Unfortunately, the standardization of analytical methods to isolate and quantify circulating cells and extracellular vesicles, as well as their extracted biochemical constituents, is still cumbersome, time-consuming, and expensive. To address these limitations, we have developed a prototype of a portable, miniaturized instrument that uses immunoaffinity capillary electrophoresis (IACE) to isolate, concentrate, and analyze cell-free biomarkers and/or tissue or cell extracts present in biological fluids. Isolation and concentration of analytes is accomplished through binding to one or more biorecognition affinity ligands immobilized to a solid support, while separation and analysis are achieved by high-resolution capillary electrophoresis (CE) coupled to one or more detectors. When compared to other existing methods, the process of this affinity capture, enrichment, release, and separation of one or a panel of biomarkers can be carried out on-line with the advantages of being rapid, automated, and cost-effective. Additionally, it has the potential to demonstrate high analytical sensitivity, specificity, and selectivity. As the potential of liquid biopsy grows, so too does the demand for technical advances. In this review, we therefore discuss applications and limitations of liquid biopsy and hope to introduce the idea that our affinity capture-separation device could be used as a form of point-of-care (POC) diagnostic technology to isolate, concentrate, and analyze circulating cells, extracellular vesicles, and viruses.

circRNA_0084043 contributes to the progression of diabetic retinopathy via sponging miR-140-3p and inducing TGFA gene expression in retinal pigment epithelial cells

Diabetic retinopathy (DR) is a frequent complication of diabetes and it can lead to visual impairment and blindness. However, the mechanism of their regulation remains little known. circRNAs can function as crucial competing endogenous RNA, which can sponge corresponding miRNAs and affect mRNA expression in various diseases, including DR. In our current research, we observed that circRNA_0084043 was elevated in high glucose (HG)-incubated ARPE-19 cells. Then, we focused on whether and how circRNA_0084043 participated in retinal vascular dysfunction under conditions diabetes. Apoptosis, inflammation and oxidative stress are hallmark of DR progression. This work was aimed to investigate the signaling mechanisms of circRNA_0084043 in these pathogenesis of DR. We discovered loss of circRNA_0084043 significantly increased cell survival and repressed HG-triggered apoptosis. In addition, knockdown of circRNA_0084043 remarkably reduced oxidative stress as evidenced by the down-regulated malondialdehyde (MDA) content, enhanced activities of Super Oxide Dismutase (SOD) and Glutathione peroxidase (GSH-PX). Addition, silence of circRNA_0084043 effectively restrained HG-stimulated inflammation as proved by repressing inflammatory cytokines Tumor Necrosis Factor α (TNF-α), Interleukin 6 (IL-6) and Cox-2 in ARPE-19 cells. Subsequently, we successfully predicted that miR-140-3p was a downstream target of circRNA_0084043, which could be negatively regulated by circRNA_0084043. Mechanistically, loss of miR-140-3p abrogated the beneficial effects of circRNA_0084043 siRNA on ARPE-19 cells. Transforming Growth Factor alpha (TGFA) can exhibit a role in multiple diseases. Taken these together, these data demonstrated that loss of circRNA_0084043 depressed HG-induced damage via sponging miR-140-3p and regulating TGFA.