Abnormal levels of mitochondrial Ca2+ channel proteins in plasma neuron-derived extracellular vesicles of early schizophrenia

Integrated technologies for molecular profiling of genetic and modified biomarkers in extracellular vesicles

Extracellular vesicles (EVs) are nanoscale membrane vesicles actively released by cells into a variety of biofluids. EVs carry myriad molecular cargoes; these include classical genetic biomarkers inherited from the parent cells as well as EV modifications by other entities (e.g., small molecule drugs). Aided by these diverse cargoes, EVs enable long-distance intercellular communication and have been directly implicated in various disease pathologies. As such, EVs are being increasingly recognized as a source of valuable biomarkers for minimally-invasive disease diagnostics and prognostics. Despite the clinical potential, EV molecular profiling remains challenging, especially in clinical settings. Due to the nanoscale dimension of EVs as well as the abundance of contaminants in biofluids, conventional EV detection methods have limited resolution, require extensive sample processing and can lose rare biomarkers. To address these challenges, new micro- and nanotechnologies have been developed to discover EV biomarkers and empower clinical applications. In this review, we introduce EV biogenesis for different cargo incorporation, and discuss the use of various EV biomarkers for clinical applications. We also assess different chip-based integrated technologies developed to measure genetic and modified biomarkers in EVs. Finally, we highlight future opportunities in technology development to facilitate the clinical translation of various EV biomarkers.

Potential of extracellular vesicle cargo as molecular signals in Schizophrenia: a scoping review

The diagnosis of schizophrenia (SCZ) primarily relies on clinical history and mental status assessments by trained professionals. There has been a search for biomarkers to facilitate laboratory diagnosis. Since extracellular vesicles (EVs) communicate with brain cells and can easily cross blood-brain barrier, there is increased interest among experts to explore them as potential molecular signals for disease detection. A scoping review was conducted to provide a comprehensive summary of the existing literature to identify the differentially expressed molecular signals in EVs isolated from SCZ patients. The methodological framework outline provided by Arksey and O'Malley was employed to conduct this scoping review. A systematic search was conducted using a search string across four databases, ultimately leading to selection of 24 relevant studies. Over 1122 differentially expressed biomolecules were identified in EVs extracted from biological fluids and tissues that can be primarily categorized as RNAs, proteins, and metabolites. Among them, 83 biomolecules were identified as validated differentially expressed molecular signals, which included metabolites, circRNAs, lncRNAs, miRNAs, and proteins. These biomolecules were found to affect cellular receptors and intracellular pathways, neurotransmitters, mitochondrial functions, immune-related functions, and metabolic pathways, which could serve as potential biomarkers for SCZ diagnosis.

Aberrant Modular Dynamics of Functional Networks in Schizophrenia and Their Relationship with Neurotransmitter and Gene Expression Profiles

Introduction

Numerous studies have emphasized the time-varying modular architecture of functional brain networks and its relevance to cognitive functions in healthy participants. However, how brain modular dynamics change in schizophrenia and how these alterations relate to neurotransmitter and transcriptomic signatures have not been well elucidated.

Methods

We harmonized resting-state fMRI data from a multi-site sample including 223 patients and 279 healthy controls and applied the multilayer network method to estimate the regional module switching rate (flexibility) of functional brain connectomes. We examined aberrant flexibility in patients relative to controls and explored its relations to neurotransmitter systems and postmortem gene expression.

Results

Compared with controls, patients with schizophrenia had significantly higher flexibility in the somatomotor and right visual regions, and lower flexibility in the left parahippocampal gyrus, right supramarginal gyrus, right frontal-operculum-insula, bilateral precuneus posterior cingulate cortex, and bilateral inferior parietal gyrus. These alterations were associated with multiple neurotransmitter systems and weighted gene transcriptomic profiles. The most relevant genes were preferentially enriched for biological processes of transmembrane transport and brain development, specific cell types, and previously identified schizophrenia-related genes.

Conclusions

This study reveals aberrant modular dynamics in schizophrenia and its relations to neurotransmitter systems and schizophrenia-related transcriptomic profiles, providing insights into the understanding of the pathophysiology underlying schizophrenia.

Exploring genetic associations and drug targets for mitochondrial proteins and schizophrenia risk

Numerous observational studies have highlighted associations between mitochondrial dysfunction and schizophrenia (SCZ), yet the causal relationship remains elusive. This study aims to elucidate the causal link between mitochondria-associated proteins and SCZ. We used summary data from a genome-wide association study (GWAS) of 66 mitochondria-associated proteins in 3,301 individuals from Europe, as well as a GWAS on the large, multi-ethnic ancestry of SCZ, involving 76,755 cases and 243,649 controls. We conducted bidirectional two-sample Mendelian randomization (MR) analyses, with inverse variance weighting (IVW) as the primary method. To account for multi-directionality and ensure robustness, we included MR-Egger, weighted median (WM), weighted mode, and simple mode methods as supplementary sensitivity analyses. Moreover, we explored the GWAS catalog and the Drug-Gene Interaction Database (DGIdb) to identify and evaluate potential therapeutic targets. MR analysis revealed significant genetically determined causal associations between ETHE1 (OR: 1.06), SOD (OR: 0.97), CALU3 (OR: 1.03), and C1QBP (OR: 1.05) and SCZ. According to the reverse MR analysis, a causal relationship was shown between SCZ and CA5A (OR: 1.09), DLD (OR: 1. 08), AIF1 (OR: 0.93), SerRS (OR: 0.93) and MULA of NFKB1 (OR: 0.77). After conducting the gene-drug analysis, HRG, F12, GPLD1, C1R, BCHE, CFH, PON1, and CA5A were identified as promising therapeutic targets. This present study reveals a significant causal relationship between mitochondria-associated proteins and SCZ, offering valuable insights into the disease's pathogenicity and identifying potential therapeutic targets for drug development.

Brain metabolic profiling of schizophrenia: a path towards a better understanding of the neuropathogenesis of psychosis

Schizophrenia (SCZ) is a complex psychotic syndrome whose pathogenesis involves countless protagonists, none of which, to date, can fully explain how this disorder develops. In this narrative review, an overview of the biochemical impairment is offered according to several perspectives. Indeed, the metabolic framework behind SCZ dopaminergic hypotheses, glutamate - gamma-amynobutyric acid dysregulation, norepinephrine and serotonin, calcium channel dysfunction is addressed together with the energetic impairment, involving glucose and lipids in SCZ etiopathogenesis, in order to highlight the multilevel pathways affected in this neuropsychiatric disorder. Furthermore, neuroinflammation is analyzed, by virtue of its important role, widely investigated in recent years, in neurodegeneration. Tracing the neurotransmitter activity at the brain level by assessing the metabolic network behind the abovementioned molecules puts into light as unavoidable the need for future studies to adopt an integrate approach to address SCZ pathological and clinical picture. The combination of all these factors, essential in acquiring an overview on the complexity of SCZ pathophysiology represents a crucial step in the development of a more targeted management of SCZ patients.

Psychotic Disorders and exosomes: An overview of current evidence and future directions

Due to its reliance on heterogeneous symptomatology, the accurate diagnosis of psychotic disorders remains a challenging task in clinical practice. Precise and early diagnosis of psychotic disorders facilitates early intervention, which has been shown to have substantial benefits for long-term outcomes. Still, the lack of specific biomarkers is an important limitation in early diagnosis and intervention. Exosomes, which act as messengers between cells, including brain cells, contain a vast array of molecules that hold promise for unveiling disorder-specific abnormalities. In this review, we discuss recent evidence highlighting the potential of circulating exosomes and brain-derived exosomes as valuable tools for the identification of accessible, non-invasive, and blood-based biomarkers of psychotic symptomatology and risk. We discuss current limitations in biomarker discovery studies focusing on exosomes. To enhance diagnosis specificity and treatment response, we also provide guidance for future investigations that need to target biomarkers of risk and relapse, as well as consider duration of untreated psychosis, biological sex, and other factors in the multifactorial biosignature of psychosis.

Identification of Schizophrenia Susceptibility Loci in the Urban Taiwanese Population

Background and Objectives: Genomic studies have identified several SNP loci associated with schizophrenia in East Asian populations. Environmental factors, particularly urbanization, play a significant role in schizophrenia development. This study aimed to identify schizophrenia susceptibility loci and characterize their biological functions and molecular pathways in Taiwanese urban Han individuals. Materials and Methods: Participants with schizophrenia were recruited from the Taiwan Precision Medicine Initiative at Tri-Service General Hospital. Genotype-phenotype association analysis was performed, with significant variants annotated and analyzed for functional relevance. Results: A total of 137 schizophrenia patients and 26,129 controls were enrolled. Ten significant variants (p < 1 × 10-5) and 15 expressed genes were identified, including rs1010840 (SOWAHC and RGPD6), rs11083963 (TRPM4), rs11619878 (LINC00355 and LINC01052), rs117010638 (AGBL1 and MIR548AP), rs1170702 (LINC01680 and LINC01720), rs12028521 (KAZN and PRDM2), rs12859097 (DMD), rs1556812 (ATP11A), rs78144262 (LINC00977), and rs9997349 (ENPEP). These variants and associated genes are involved in immune response, blood pressure regulation, muscle function, and the cytoskeleton. Conclusions: Identified variants and associated genes suggest a potential genetic predisposition to schizophrenia in the Taiwanese urban Han population, highlighting the importance of potential comorbidities, considering population-specific genetic and environmental interactions.

Neuroprotective effects of annexin A1 tripeptide in rats with sepsis-associated encephalopathy

Sepsis-associated encephalopathy (SAE) is characterized by high incidence and mortality rates, with limited treatment options available. The underlying mechanisms and pathogenesis of SAE remain unclear. Annexin A1 (ANXA1), a membrane-associated protein, is involved in various in vivo pathophysiological processes. This study aimed to explore the neuroprotective effects and mechanisms of a novel bioactive ANXA1 tripeptide (ANXA1sp) in SAE. Forty Sprague-Dawley rats were randomly divided into four groups (n = 10 each): control, SAE (intraperitoneal injection of lipopolysaccharide), vehicle (SAE + normal saline), and ANXA1sp (SAE + ANXA1sp) groups. Changes in serum inflammatory factors (interleukin-6 [IL-6], tumor necrosis factor-α [TNF-α]), hippocampal reactive oxygen species (ROS), mitochondrial membrane potential (MMP), and adenosine triphosphate (ATP) levels were measured. The Morris water maze and Y maze tests were used to assess learning and memory capabilities in the rats. Further, changes in peroxisome proliferator-activated receptor-gamma (PPAR-γ) and apoptosis-related protein expression were detected using western blot. The IL-6, TNF-α, and ROS levels were significantly increased in the SAE group compared with the levels in the control group. Intraperitoneal administration of ANXA1sp led to a significant decrease in the IL-6, TNF-α, and ROS levels (p < 0.05). Compared with the SAE group, the ANXA1sp group exhibited reduced escape latency on day 5, a significant increase in the number of platform crossings and the percent spontaneous alternation, and significantly higher hippocampal MMP and ATP levels (p < 0.05). Meanwhile, the expression level of PPAR-γ protein in the ANXA1sp group was significantly increased compared with that in the other groups (p < 0.05). The expressions of apoptosis-related proteins (nuclear factor-kappa B [NF-κB], Bax, and Caspase-3) in the SAE and vehicle groups were significantly increased, with a noticeable decrease in Bcl-2 expression, compared with that noted in the control group. Moreover, the expressions of NF-κB, Bax, and Caspase-3 were significantly decreased in the ANXA1sp group, and the expression of Bcl-2 was markedly increased (p < 0.05). ANXA1sp can effectively reverse cognitive impairment in rats with SAE. The neuroprotective effect of ANXA1sp may be attributed to the activation of the PPAR-γ pathway, resulting in reduced neuroinflammatory response and inhibition of apoptosis.

Single-extracellular vesicle (EV) analyses validate the use of L1 Cell Adhesion Molecule (L1CAM) as a reliable biomarker of neuron-derived EVs

Isolation of neuron-derived extracellular vesicles (NDEVs) with L1 Cell Adhesion Molecule (L1CAM)-specific antibodies has been widely used to identify blood biomarkers of CNS disorders. However, full methodological validation requires demonstration of L1CAM in individual NDEVs and lower levels or absence of L1CAM in individual EVs from other cells. Here, we used multiple single-EV techniques to establish the neuronal origin and determine the abundance of L1CAM-positive EVs in human blood. L1CAM epitopes of the ectodomain are shown to be co-expressed on single-EVs with the neuronal proteins β-III-tubulin, GAP43, and VAMP2, the levels of which increase in parallel with the enrichment of L1CAM-positive EVs. Levels of L1CAM-positive EVs carrying the neuronal proteins VAMP2 and β-III-tubulin range from 30% to 63%, in contrast to 0.8%-3.9% of L1CAM-negative EVs. Plasma fluid-phase L1CAM does not bind to single-EVs. Our findings support the use of L1CAM as a target for isolating plasma NDEVs and leveraging their cargo to identify biomarkers reflecting neuronal function.

Neuron-derived extracellular vesicles in blood reveal effects of exercise in Alzheimer's disease

BACKGROUND

Neuron-derived extracellular vesicles (NDEVs) in blood may be used to derive biomarkers for the effects of exercise in Alzheimer's disease (AD). For this purpose, we studied changes in neuroprotective proteins proBDNF, BDNF, and humanin in plasma NDEVs from patients with mild to moderate AD participating in the randomized controlled trial (RCT) of exercise ADEX.

METHODS

proBDNF, BDNF, and humanin were quantified in NDEVs immunocaptured from the plasma of 95 ADEX participants, randomized into exercise and control groups, and collected at baseline and 16 weeks. Exploratorily, we also quantified NDEV levels of putative exerkines known to respond to exercise in peripheral tissues.

RESULTS

NDEV levels of proBDNF, BDNF, and humanin increased in the exercise group, especially in APOE ε4 carriers, but remained unchanged in the control group. Inter-correlations between NDEV biomarkers observed at baseline were maintained after exercise. NDEV levels of putative exerkines remained unchanged.

CONCLUSIONS

Findings suggest that the cognitive benefits of exercise could be mediated by the upregulation of neuroprotective factors in NDEVs. Additionally, our results indicate that AD subjects carrying APOE ε4 are more responsive to the neuroprotective effects of physical activity. Unchanged NDEV levels of putative exerkines after physical activity imply that exercise engages different pathways in neurons and peripheral tissues. Future studies should aim to expand upon the effects of exercise duration, intensity, and type in NDEVs from patients with early AD and additional neurodegenerative disorders.

TRIAL REGISTRATION

The Effect of Physical Exercise in Alzheimer Patients (ADEX) was registered in ClinicalTrials.gov on April 30, 2012 with the identifier NCT01681602.

The role of Extracellular Genomic Materials (EGMs) in psychiatric disorders

Extracellular Genomic Materials (EGMs) are the nucleic acids secreted or released from all types of cells by endogenous or exogenous stimuli through varying mechanisms into the extracellular region and inevitably to all biological fluids. EGMs could be found as free, protein-bound, and/ or with vesicles. EGMs can potentially have immunophenotypic and/or genotypic characteristics of a cell of origin, travel to distant organs, and interact with the new microenvironment. To achieve all, EGMs might bi-directionally transit through varying membranes, including the blood-brain barrier. Such ability provides the transfer of any information related to the pathophysiological changes in psychiatric disorders in the brain to the other distant organ systems or vice versa. In this article, many aspects of EGMs have been elegantly reviewed, including their potential in diagnosis as biomarkers, application in treatment modalities, and functional effects in the pathophysiology of psychiatric disorders. The psychiatric disorders were studied under subgroups of Schizophrenia spectrum disorders, bipolar disorder, depressive disorders, and an autism spectrum disorders. EGMs provide a robust and promising tool in clinics for prognosis and diagnosis. The successful application of EGMs into treatment modalities might further provide encouraging outcomes for researchers and clinicians in psychiatric disorders.

Research progress in role of exosomes exosomes in mental disorders

Exosomes are a class of extracellular vesicles with a structure of lipid bilayer-membrane. In the central nervous system (CNS), exosomes can be secreted from both neurons and glial cells. Exosomes released into the extracellular matrix can freely cross the blood-brain barrier and function as crucial carriers of cellular communication and substance exchange in the CNS. Exosomes play a key role in the pathological process of mental disorders such as schizophrenia, depression, and bipolar disorder, and they have the potential to be used as a targeted carrier of antipsychotic medications. Exosomes are likely to become a new tool in the future to aid in the early prevention, accurate diagnosis, and effective treatment for people with mental disorders.

An NIMH Workshop on Non-Affective Psychosis in Midlife and Beyond: Research Agenda on Phenomenology, Clinical Trajectories, Underlying Mechanisms, and Intervention Targets

We present a review of the state of the research in the phenomenology, clinical trajectories, biological mechanisms, aging biomarkers, and treatments for middle-aged and older people with schizophrenia (PwS) discussed at the NIMH sponsored workshop "Non-affective Psychosis in Midlife and Beyond." The growing population of PwS has specific clinical needs that require tailored and mechanistically derived interventions. Differentiating between the effects of aging and disease progression is a key challenge of studying older PwS. This review of the workshop highlights the recent findings in this understudied clinical population and the critical gaps in knowledge and consensus for research priorities. This review showcases the major challenges and opportunities for research to advance clinical care for this growing and understudied population.

Reduced numbers of naïve CD4 + T cells and an altered CD4/CD8 balance in depressed common variable immune deficiency (CVID) patients. Is thymosin-α1 a possible treatment?

In the 1990's the macrophage-T-cell-theory of depression was posed stating that low grade inflammation and an abnormal T cell system destabilize the development and function of the emotional brain in such a way, that individuals become ultrasensitive to stress. Recently we gathered evidence that indeed higher frequencies of CD4+ memory T cells, lower frequencies of naive CD4 + T cells, higher frequencies of CD8 + T cells (the latter two in part elicited by Cytomegalovirus, CMV, infection) are a characteristic of Major Depressive Disorder (MDD). In MDD patients with a history of childhood trauma and severe depression monocytes are inflammatory activated. Low grade inflammation and T cell system defects have also been reported in patients with Common Variable Immune Deficiency (CVID) (next to antibody production defects). CVID patients show a higher prevalence of mild depression. The aim of this study was to determine T cell frequencies and monocyte inflammatory activation in CVID patients with and without depression. This study confirms that CVID patients have CMV independent decreases in the frequency of naïve CD4 + T cells and it de novo shows a CMV dependent increase in the expression of inflammatory genes in monocytes. CVID patients with depression are additionally characterized by a CMV independent increase in the frequency of naïve CD8 + T cells, while lacking monocyte inflammatory activation. In conclusion, depressed CVID patients have T cell abnormalities comparable to that of patients with regular MDD. These abnormalities are presently targeted by thymosin α1 in an open-label proof of concept trial.