Genome-wide expression profiling of human lymphoblastoid cell lines implicates integrin beta-3 in the mode of action of antidepressants

MicroRNAs as Diagnostic Biomarkers and Predictors of Antidepressant Response in Major Depressive Disorder: A Systematic Review

Despite the hardships of major depressive disorder (MDD), biomarkers for the diagnosis and pharmacological management of this condition are lacking. MicroRNAs are epigenetic mechanisms that could provide promising MDD biomarkers. Our aim was to summarize the findings and provide validation for the selection and use of specific microRNAs as biomarkers in the diagnosis and treatment of MDD. A systematic review was conducted using the PubMed/Medline, Cochrane, PsycINFO, Embase, and LILACS databases from March 2022 to November 2023, with clusters of terms based on "microRNA" and "antidepressant". Studies involving human subjects, animal models, and cell cultures were included, whereas those that evaluated herbal medicines, non-pharmacological therapies, or epigenetic mechanisms other than miRNA were excluded. The review revealed differences in the expression of various microRNAs when considering the time of assessment (before or after antidepressant treatment) and the population studied. However, due to the heterogeneity of the microRNAs investigated, the limited size of the samples, and the wide variety of antidepressants used, few conclusions could be made. Despite the observed heterogeneity, the following microRNAs were determined to be important factors in MDD and the antidepressant response: mir-1202, mir-135, mir-124, and mir-16. The findings indicate the potential for the use of microRNAs as biomarkers for the diagnosis and treatment of MDD; however, more homogeneous studies are needed.

The role of integrin beta in schizophrenia: a preliminary exploration

Integrins are transmembrane heterodimeric (αβ) receptors that transduce mechanical signals between the extracellular milieu and the cell in a bidirectional manner. Extensive research has shown that the integrin beta (β) family is widely expressed in the brain and that they control various aspects of brain development and function. Schizophrenia is a relatively common neurological disorder of unknown etiology and has been found to be closely related to neurodevelopment and neurochemicals in neuropathological studies of schizophrenia. Here, we review literature from recent years that shows that schizophrenia involves multiple signaling pathways related to neuronal migration, axon guidance, cell adhesion, and actin cytoskeleton dynamics, and that dysregulation of these processes affects the normal function of neurons and synapses. In fact, alterations in integrin β structure, expression and signaling for neural circuits, cortex, and synapses are likely to be associated with schizophrenia. We explored several aspects of the possible association between integrin β and schizophrenia in an attempt to demonstrate the role of integrin β in schizophrenia, which may help to provide new insights into the study of the pathogenesis and treatment of schizophrenia.

Impaired myelin ultrastructure is reversed by citalopram treatment in a mouse model for major depressive disorder

Major depressive disorder (MDD) is the most common and widespread mental disorder. Selective serotonin reuptake inhibitors (SSRIs) are the first-line treatment for MDD. The relation between the inhibition of serotonin reuptake in the central nervous system and remission from MDD remains controversial, as reuptake inhibition occurs rapidly, but remission from MDD takes weeks to months. Myelination-related deficits and white matter abnormalities were shown to be involved in psychiatric disorders such as MDD. This may explain the delay in remission following SSRI administration. The raphe nuclei (RN), located in the brain stem, consist of clusters of serotonergic (5-HT) neurons that project to almost all regions of the brain. Thus, the RN are an intriguing area for research of the potential effect of SSRI on myelination, and their involvement in MDD. MicroRNAs (miRNAs) regulate many biological features that might be altered by antidepressants. Two cohorts of chronic unpredictable stress (CUS) mouse model for depression underwent behavioral tests for evaluating stress, anxiety, and depression levels. Following application of the CUS protocol and treatment with the SSRI, citalopram, 48 mice of the second cohort were tested via magnetic resonance imaging and diffusion tensor imaging for differences in brain white matter tracts. RN and superior colliculus were excised from both cohorts and measured for changes in miRNAs, mRNA, and protein levels of candidate genes. Using MRI-DTI scans we found lower fractional anisotropy and axial diffusivity in brains of stressed mice. Moreover, both miR-30b-5p and miR-101a-3p were found to be downregulated in the RN following CUS, and upregulated following CUS and citalopram treatment. The direct binding of these miRNAs to Qki, and the subsequent effects on mRNA and protein levels of myelin basic protein (Mbp), indicated involvement of these miRNAs in myelination ultrastructure processes in the RN, in response to CUS followed by SSRI treatment. We suggest that SSRIs are implicated in repairing myelin deficits resulting from chronic stress that leads to depression.

High purity and integrity RNA from human cell lines stored in liquid nitrogen for over 20 years

Biobanks are a key resource for obtaining human cell lines for biomedical research, including for drug development projects. Such projects often include comparative RNA-sequencing of large panels of human cell lines from individuals affected by certain disorders and healthy controls, or from individuals with different drug response phenotypes. RNA extractions are typically done from growing cell cultures, a process that may take several weeks. However, maintaining large numbers of cell lines in parallel increases the project workload. Here, we show that extracting RNAs directly from frozen vials of human cell lines stored for over 20 years in a liquid nitrogen freezer yields RNAs with the high purity and integrity parameters that conform to those required for optimal RNA-sequencing and are closely similar to those obtained for RNAs extracted from growing human cell lines.

Up-Regulation of S100 Gene Family in Brain Samples of a Subgroup of Individuals with Schizophrenia: Meta-analysis

The S100 proteins family is known to affect neuroinflammation and astrocyte activation, which have been suggested to be contributors to the pathogenesis of schizophrenia. We conducted a systematic meta-analysis of S100 genes differential expression in postmortem samples of patients with schizophrenia vs. healthy controls, following the commonly used Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Twelve microarray datasets met the inclusion criteria (overall 511 samples, 253 schizophrenia and 258 controls were analyzed). Nine out of 21 genes were significantly up-regulated or with tendency for up-regulation. A per-sample fold change analysis indicated that the S100 genes' up-regulation was concentrated in a subgroup of the patients. None of the genes have been found to be down-regulated. ANXA3, which encodes Annexin 3 protein and was associated with neuroinflammation, was up-regulated and positively correlated with the S100 genes' expression pattern. In addition, astrocytes and endothelial cell markers were significantly correlated with S100A8 expression. S100 correlation with ANXA3 and endothelial cell markers suggests that the up-regulation we detected reflects increased inflammation. However, it might also reflect astrocytes abundance or activation. The fact that S100 proteins were shown to be up-regulated in blood samples and other body fluids of patients with schizophrenia suggests a potential role as biomarkers, which might help disease subtyping, and the development of etiological treatments for immune dysregulation in schizophrenia.

Epigenetic regulation in major depression and other stress-related disorders: molecular mechanisms, clinical relevance and therapeutic potential

Major depressive disorder (MDD) is a chronic, generally episodic and debilitating disease that affects an estimated 300 million people worldwide, but its pathogenesis is poorly understood. The heritability estimate of MDD is 30-40%, suggesting that genetics alone do not account for most of the risk of major depression. Another factor known to associate with MDD involves environmental stressors such as childhood adversity and recent life stress. Recent studies have emerged to show that the biological impact of environmental factors in MDD and other stress-related disorders is mediated by a variety of epigenetic modifications. These epigenetic modification alterations contribute to abnormal neuroendocrine responses, neuroplasticity impairment, neurotransmission and neuroglia dysfunction, which are involved in the pathophysiology of MDD. Furthermore, epigenetic marks have been associated with the diagnosis and treatment of MDD. The evaluation of epigenetic modifications holds promise for further understanding of the heterogeneous etiology and complex phenotypes of MDD, and may identify new therapeutic targets. Here, we review preclinical and clinical epigenetic findings, including DNA methylation, histone modification, noncoding RNA, RNA modification, and chromatin remodeling factor in MDD. In addition, we elaborate on the contribution of these epigenetic mechanisms to the pathological trait variability in depression and discuss how such mechanisms can be exploited for therapeutic purposes.

VDAC genes down-regulation in brain samples of individuals with schizophrenia is revealed by a systematic meta-analysis

Mitochondrial dysfunction was shown to be involved in schizophrenia pathophysiology. Abnormal energy states can lead to alterations in neural function and thereby to the cognitive and behavioral aberrations characteristics of schizophrenia. Voltage-dependent anion-selective channels (VDAC) are located in the outer mitochondrial membrane and are involved in mitochondrial energy production. Only few studies explored VDAC genes' expression in schizophrenia, and their results were not consistent. We conducted a systematic meta-analysis of ten brain samples gene expression datasets (overall 368 samples, 179 schizophrenia, 189 controls). In addition, we conducted a meta-analysis of three blood samples datasets (overall 300 samples, 167 schizophrenia, 133 controls). Pairwise correlation analysis was conducted between the VDAC and proteasome subunit genes' expression patterns. VDAC1, VDAC2 and VDAC3 showed significant down-regulation in brain samples of patients with schizophrenia. They also showed significant positive correlations with the proteasome subunit genes' expression levels. Our findings suggest that VDAC genes might play a role in mitochondrial dysfunction in schizophrenia. VDAC1 was down-regulated also in blood samples, which suggests its potential role as a biomarker for schizophrenia. The correlation with proteasome subunits, which were previously shown to be down-regulated in a subgroup of the patients, suggests that our findings might characterize a subgroup of the patients. This direction has the potential to lead to patients' stratification and more precisely-targeted therapy and necessitates further study.

Natural Phytochemicals for the Treatment of Major Depressive Disorder: A Mini-Review of Pre- and Clinical Studies

Major Depressive Disorder (MDD) is a common mental illness that causes significant disability and declining quality of life. An overlap of multiple factors can be involved in the pathophysiology of this mood disorder, including increased inflammation and oxidative stress, change in neurotransmitters, decreased brain-derived neurotrophic factor (BDNF), activation of the hypothalamicpituitary- adrenal (HPA) axis, and changes in the microbiota-gut-brain axis. Although the classic treatment for MDD is safe, it is far from ideal, with delay to start the best clinic, side effects, and a large number of non-responses or partial-responses. Therefore, other alternatives are being studied to improve depressive symptoms, and, among them, the role of phytochemicals in food stands out. This mini-review will discuss the main phytochemicals present in foods with clinical and preclinical studies showing benefits for MDD treatment. In addition, the main mechanisms of action that are being proposed for each of these compounds will be addressed.

Estradiol reduces ACE2 and TMPRSS2 mRNA levels in A549 human lung epithelial cells

Epidemiologic studies suggest slightly higher risk of severe Covid‐19 symptoms and fatalities following SARS‐CoV‐2 infection in men compared with women from similar age groups. This bias was suggested to reflect differences in the male and female immune system regulation, driven by different sex hormone levels in men and women, in particular, higher plasma estradiol in women. SARS‐CoV‐2 infects respiratory tract epithelial cells by binding to their cell membrane ACE2, followed by priming for cell entry by the host cell membrane serine protease TMPRSS2. The cell protease FURIN facilitates cell exit of mature SARS‐CoV‐2 virions. Our study examined the effects of in vitro treatment of A549 human lung epithelial cells with 17‐β‐estradiol on mRNA expression of genes coding for these proteins. Treatment of A549 human lung epithelial cells with 17‐β‐estradiol reduced the cellular mRNA levels of ACE2 and TMPRSS2 mRNA, while not affecting FURIN expression. Our findings suggest that 17‐β‐estradiol may reduce SARS‐CoV‐2 infection of lung epithelial cells, which may in part explain the reduced incidence of severe Covid‐19 and fatalities among women compared with men of similar age. Studies into the molecular pathways by which 17‐β‐estradiol reduces ACE2 and TMPRSS2 mRNA expression in lung epithelial cells are needed for assessing its potential protective value against severe Covid‐19.

d-Galactose treatment increases ACE2, TMPRSS2, and FURIN and reduces SERPINA1 mRNA expression in A549 human lung epithelial cells

Several comorbidities including diabetes, immune deficiency, and chronic respiratory disorders increase the risk of severe Covid-19 and fatalities among SARS-CoV-2 infected individuals. Severe Covid-19 risk among diabetes patients may reflect reduced immune response to viral infections. SARS-CoV-2 initially infects respiratory tract epithelial cells by binding to the host cell membrane ACE2, followed by proteolytic priming for cell entry by the host cell membrane serine protease TMPRSS2. Additionally, the protease FURIN facilitates cell exit of mature SARS-CoV-2 virions. Alpha-1 antitrypsin (AAT), the major plasma serine protease inhibitor, encoded by SERPINA1, is known to promote immune response to viral infections. AAT inhibits neutrophil elastase, a key inflammatory serine protease implicated in alveolar cell damage during respiratory infections, and AAT deficiency is associated with susceptibility to lung infections. AAT is implicated in Covid-19 as it inhibits TMPRSS2, a protease essential for SARS-CoV-2 cell entry. Here we show that treatment of A549 human lung epithelial cells for 7 days with 25 mM d-galactose, an inducer of diabetic-like and oxidative stress cellular phenotypes, leads to increased mRNA levels of ACE2, TMPRSS2, and FURIN, along with reduced SERPINA1 mRNA. Together, the dysregulated transcription of these genes following d-galactose treatment suggests that chronic diabetic-like conditions may facilitate SARS-CoV-2 infection of lung epithelial cells. Our findings may in part explain the higher severe Covid-19 risk in diabetes, and highlight the need to develop special treatment protocols for diabetic patients.

Blood transcriptional response to treatment-resistant depression during electroconvulsive therapy

Selective serotonin reuptake inhibitors (SSRIs) are currently the first-line antidepressant drug treatment for major depressive disorder (MDD). Treatment-resistant depression (TRD), defined as failure to achieve remission despite adequate treatment, affects ~30% of persons with MDD. The current recommended treatment for TRD is electroconvulsive therapy (ECT), while ketamine is an experimentally suggested treatment. This study aimed to elucidate the transcriptional differences in peripheral blood mononuclear cells (PBMC) between individuals with TRD and a control group without a psychiatric illness; and between patients with TRD, treated with either standard antidepressant drugs alone, or in combination with ECT or ketamine. Additionally, PBMC transcriptomics were compared between treatment responders, following completion of their treatment protocols. Total RNA was extracted from PBMC of the TRD group at two time points, and RNA and miRNA expression were profiled. Multiple mRNAs and miRNAs were found to be modified, with two protein coding genes, FKBP5 and ITGA2B, which are up- and downregulated, respectively; and several miRNAs have shown changes following successful ECT treatment. Further analysis demonstrated the direct functional regulation of ITGA2B by miR-24-3p. Our findings suggest that PBMC expression levels of FKBP5, ITGA2B, and miR-24-3p should be further explored as tentative ECT response biomarkers.

Synergy of oxytocin and citalopram in modulating Itgb3/Chl1 interplay: Relevance to sensitivity to SSRI therapy

Intranasal treatment with oxytocin showed beneficial effects in post-traumatic stress disorder and autism spectrum disorders; however, it was not investigated as much in depression. Keeping in mind the favorable effects of oxytocin on animal models of anxiety and depression, we postulated that synergy between prescribed first choice drugs, selective serotonin reuptake inhibitors (SSRIs) and oxytocin could improve the treatment outcome compared with SSRI monotherapy. Our previous in vitro genome-wide transcriptomic study on human lymphoblastoid cell lines exposed to paroxetine resulted in increase of integrin β3 (ITGB3) gene expression, and further, ITGB3/CHL1 expression ratio was hypothesized to influence the sensitivity to SSRIs. The aim of this report was to explore molecular mechanisms behind the antidepressant-like oxytocin effect, alone and in synergy with citalopram, on behavioral and molecular level in corticosterone treated rats, a paradigm used to model anxiety and depression in animals. Oxytocin treatment (1) ameliorated corticosterone-induced reduction of neurogenesis and number of parvalbumin-positive interneurons in the hippocampal CA1 region, (2) enhanced anxiolytic- and antidepressant-like effects of citalopram in the open field test, and (3) the SSRI/oxytocin synergy persisted in reversing the reduction of the Itgb3 gene expression and increased Itgb3/Chl1 ratio in the prefrontal cortices. These results support the existence of synergy between citalopram and oxytocin in reversing the molecular and behavioral changes induced by corticosterone treatment and point to possible molecular mechanisms behind antidepressant-like effect of oxytocin.

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.

Changes in concentrations of NMDA receptor subunit GluN2B, Arc and syntaxin-1 in dorsal hippocampus Schaffer collateral synapses in a rat learned helplessness model of depression

Major depressive disorder involves changes in synaptic structure and function, but the molecular underpinnings of these changes are still not established. In an initial pilot experiment, whole-brain synaptosome screening with quantitative western blotting was performed to identify synaptic proteins that may show concentration changes in a congenital rat learned helplessness model of depression. We found that the N-methyl-d-aspartate receptor (NMDAR) subunits GluN2A/GluN2B, activity-regulated cytoskeleton-associated protein (Arc) and syntaxin-1 showed significant concentration differences between congenitally learned helpless (LH) and nonlearned helpless (NLH) rats. Having identified these three proteins, we then performed more elaborate quantitative immunogold electron microscopic analyses of the proteins in a specific synapse type in the dorsal hippocampus: the Schaffer collateral synapse in the CA1 region. We expanded the setup to include also unstressed wild-type (WT) rats. The concentrations of the proteins in the LH and NLH groups were compared to WT animals. In this specific synapse, we found that the concentration of NMDARs was increased in postsynaptic spines in both LH and NLH rats. The concentration of Arc was significantly increased in postsynaptic densities in LH animals as well as in presynaptic cytoplasm of NLH rats. The concentration of syntaxin-1 was significantly increased in both presynaptic terminals and postsynaptic spines in LH animals, while pre- and postsynaptic syntaxin-1 concentrations were significantly decreased in NLH animals. These protein changes suggest pathways by which synaptic plasticity may be increased in dorsal hippocampal Schaffer collateral synapses during depression, corresponding to decreased synaptic stability.

Cell Adhesion Molecules Involved in Neurodevelopmental Pathways Implicated in 3p-Deletion Syndrome and Autism Spectrum Disorder

Autism spectrum disorder (ASD) is characterized by impaired social interaction, language delay and repetitive or restrictive behaviors. With increasing prevalence, ASD is currently estimated to affect 0.5–2.0% of the global population. However, its etiology remains unclear due to high genetic and phenotypic heterogeneity. Copy number variations (CNVs) are implicated in several forms of syndromic ASD and have been demonstrated to contribute toward ASD development by altering gene dosage and expression. Increasing evidence points toward the p-arm of chromosome 3 (chromosome 3p) as an ASD risk locus. Deletions occurring at chromosome 3p result in 3p-deletion syndrome (Del3p), a rare genetic disorder characterized by developmental delay, intellectual disability, facial dysmorphisms and often, ASD or ASD-associated behaviors. Therefore, we hypothesize that overlapping molecular mechanisms underlie the pathogenesis of Del3p and ASD. To investigate which genes encoded in chromosome 3p could contribute toward Del3p and ASD, we performed a comprehensive literature review and collated reports investigating the phenotypes of individuals with chromosome 3p CNVs. We observe that high frequencies of CNVs occur in the 3p26.3 region, the terminal cytoband of chromosome 3p. This suggests that CNVs disrupting genes encoded within the 3p26.3 region are likely to contribute toward the neurodevelopmental phenotypes observed in individuals affected by Del3p. The 3p26.3 region contains three consecutive genes encoding closely related neuronal immunoglobulin cell adhesion molecules (IgCAMs): Close Homolog of L1 (CHL1), Contactin-6 (CNTN6), and Contactin-4 (CNTN4). CNVs disrupting these neuronal IgCAMs may contribute toward ASD phenotypes as they have been associated with key roles in neurodevelopment. CHL1, CNTN6, and CNTN4 have been observed to promote neurogenesis and neuronal survival, and regulate neuritogenesis and synaptic function. Furthermore, there is evidence that these neuronal IgCAMs possess overlapping interactomes and participate in common signaling pathways regulating axon guidance. Notably, mouse models deficient for these neuronal IgCAMs do not display strong deficits in axonal migration or behavioral phenotypes, which is in contrast to the pronounced defects in neuritogenesis and axon guidance observed in vitro. This suggests that when CHL1, CNTN6, or CNTN4 function is disrupted by CNVs, other neuronal IgCAMs may suppress behavioral phenotypes by compensating for the loss of function.

Gene expression meta-analysis reveals the up-regulation of CREB1 and CREBBP in Brodmann Area 10 of patients with schizophrenia

Cognitive impairments characterize individuals with schizophrenia, and are correlated to the patients' functional outcome. The transcription factor Cyclic AMP-responsive element-binding protein-1 (CREB1) is involved in learning and memory processes. CREB1 and both CREB-binding protein (CREBBP) and E1A Binding Protein P300 (EP300), co-activators of CREB1, have been associated with schizophrenia. We performed a systematic meta-analysis of CREB1, CREBBP and EP300 differential expression in post mortem Brodmann Area 10 (BA10) samples of patients with schizophrenia vs. healthy controls, following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. Two microarray datasets met the inclusion criteria (overall 41 schizophrenia samples and 38 controls were analyzed). We detect up-regulation of CREB1 and CREBBP in BA10 samples of patients with schizophrenia, while EP300 wasn't differentially expressed. The integration of two independent datasets and the positive correlation between the expression patterns of CREB1 and CREBBP increase the validity of the results. The up-regulation of CREB1 and its co-activator CREBBP might relate to BA10 altered activation that has been shown in schizophrenia. As BA10 was shown to be involved in the cognitive impairments associated with schizophrenia, this suggests involvement of CREB1 and CREBBP in the cognitive symptoms that characterize the disease.

Integrin adhesion in brain assembly: From molecular structure to neuropsychiatric disorders

Integrins are extracellular matrix receptors that mediate biochemical and mechanical bi-directional signals between the extracellular and intracellular environment of a cell thanks to allosteric conformational changes. In the brain, they are found in both neurons and glial cells, where they play essential roles in several aspects of brain development and function, such as cell migration, axon guidance, synaptogenesis, synaptic plasticity and neuro-inflammation. Although there are many successful examples of how regulating integrin adhesion and signaling can be used for therapeutic purposes, for example for halting tumor progression, this is not the case for the brain, where the growing evidence of the importance of integrins for brain pathophysiology has not translated yet into medical applications. Here, we review recent literature showing how alterations in integrin structure, expression and signaling may be involved in the etiology of autism spectrum disorder, epilepsy, schizophrenia, addiction, depression and Alzheimer's disease. We focus on common mechanisms and recurrent signaling pathways, trying to bridge studies on the genetics and molecular structure of integrins with those on synaptic physiology and brain pathology. Further, we discuss integrin-targeting strategies and their potential benefits for therapeutic purposes in neuropsychiatric disorders.

Genomics and the future of psychopharmacology: MicroRNAs offer novel therapeutics

MicroRNAs (miRNAs) are short, noncoding RNAs functioning as regulators of the transcription of protein-coding genes in eukaryotes. During the last two decades, studies on miRNAs indicate that they have potential as diagnostic and prognostic biomarkers for a wide range of cancers. Research interest in miRNAs has moved to embrace further medical disciplines, including neuropsychiatric disorders, comparing miRNA expression and mRNA targets between patient and control blood samples and postmortem brain tissues, as well as in animal models of neuropsychiatric disorders. This manuscript reviews recent findings on miRNAs implicated in the pathology of mood disorders, schizophrenia, and autism, as well as their diagnostic potential, and their potential as tentative targets for future therapeutics. The plausible contribution of X chromosome miRNAs to the larger prevalence of major depression among women is also evaluated.


MicroRNAs expressed in depression and their associated pathways: A systematic review and a bioinformatics analysis

Depression is a debilitating mental illness, one of the most prevalent worldwide. MicroRNAs have been studied to better understand the biological mechanisms that regulate this disease. This study review systematically the literature to identify which microRNAs are currently being associated with depression and their related pathways. The electronic search was conducted in PubMed, Scopus, Scielo, ISI Web of Knowledge, and PsycINFO databases, using the search terms "Depressive Disorder" or "Depression" and "MicroRNAs". After, microRNAs that were up and down-regulated in depression were analyzed by bioinformatics. We observed that among the 77 microRNAs cited by included studies, 54 had their levels altered in depressed individuals compared to controls, 30 being up-regulated and 24 down-regulated. The bioinformatics analysis revealed that among the up-regulated microRNAs there were 81 total and 43 union pathways, with 15 presenting a significant difference. Among the down-regulated microRNAs, 67 total and 45 union pathways were found, with 14 presenting a significant difference. The miR-17-5p and let-7a-5p were the most frequently found microRNAs in the statistically significant pathways. In this study a panel of altered microRNAs in depression was created with their related pathways, which is a step towards understanding the complex network of microRNAs in depression.

miRNAs in depression vulnerability and resilience: novel targets for preventive strategies

The exposure to stressful experiences during the prenatal period and through the first years of life is known to affect the brain developmental trajectories, leading to an enhanced vulnerability for the development of several psychiatric disorders later in life. However, not all the subjects exposed to the same stressful experience develop a pathologic condition, as some of them, activating coping strategies, become more resilient. The disclosure of mechanisms associated with stress vulnerability or resilience may allow the identification of novel biological processes and potential molecules that, if properly targeted, may prevent susceptibility or potentiate resilience. Over the last years, miRNAs have been proposed as one of the epigenetic mechanisms mediating the long-lasting effects of stress. Accordingly, they are associated with the development of stress vulnerability or resilience-related strategies. Moreover, miRNAs have been proposed as possible biomarkers able to identify subjects at high risk to develop depression and to predict the response to pharmacological treatments. In this review, we aimed to provide an overview of findings from studies in rodents and humans focused on the involvement of miRNAs in the mechanisms of stress response with the final goal to identify distinct sets of miRNAs involved in stress vulnerability or resilience. In addition, we reviewed studies on alterations of miRNAs in the context of depression, showing data on the involvement of miRNAs in the pathogenesis of the disease and in the efficacy of pharmacological treatments, discussing the potential utility of miRNAs as peripheral biomarkers able to predict the treatment response.

RNA sequencing of bipolar disorder lymphoblastoid cell lines implicates the neurotrophic factor HRP-3 in lithium's clinical efficacy

Objectives: Lithium remains the oldest and most effective treatment for mood stabilisation in bipolar disorder (BD), even though at least half of patients are only partially responsive or do not respond. This study aimed to identify biomarkers associated with lithium response in BD, based on comparing RNA sequencing information derived from lymphoblastoid cell lines (LCLs) of lithium-responsive (LR) versus lithium non-responsive (LNR) BD patients, to assess gene expression variations that might bear on treatment outcome. Methods: RNA sequencing was carried out on 24 LCLs from female BD patients (12 LR and 12 LNR) followed by qPCR validation in two additional independent cohorts (41 and 17 BD patients, respectively). Results: Fifty-six genes showed nominal differential expression comparing LR and LNR (FC ≥ |1.3|, P ≤ 0.01). The differential expression of HDGFRP3 and ID2 was validated by qPCR in the independent cohorts. Conclusions: We observed higher expression levels of HDGFRP3 and ID2 in BD patients who favourably respond to lithium. Both of these genes are involved in neurogenesis, and HDGFRP3 has been suggested to be a neurotrophic factor. Additional studies in larger BD cohorts are needed to confirm the potential of HDGFRP3 and ID2 expression levels in blood cells as tentative favourable lithium response biomarkers.

Genomics and the future of psychopharmacology: MicroRNAs offer novel therapeutics

MicroRNAs (miRNAs) are short, noncoding RNAs functioning as regulators of the transcription of protein-coding genes in eukaryotes. During the last two decades, studies on miRNAs indicate that they have potential as diagnostic and prognostic biomarkers for a wide range of cancers. Research interest in miRNAs has moved to embrace further medical disciplines, including neuropsychiatric disorders, comparing miRNA expression and mRNA targets between patient and control blood samples and postmortem brain tissues, as well as in animal models of neuropsychiatric disorders. This manuscript reviews recent findings on miRNAs implicated in the pathology of mood disorders, schizophrenia, and autism, as well as their diagnostic potential, and their potential as tentative targets for future therapeutics. The plausible contribution of X chromosome miRNAs to the larger prevalence of major depression among women is also evaluated.
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MicroRNAs in Major Depressive Disorder

Major depressive disorder (MDD) is a severe and chronic psychiatric disorder with a high prevalence in the population. Although our understanding of its pathophysiological mechanisms has significantly increased over the years, available treatments still present several limitations and are not effective to all MDD patients. Epigenetic mechanisms have recently been suggested to play key roles in MDD pathogenesis and treatment, including the effects of small noncoding RNAs known as microRNAs (miRNAs). miRNAs can modulate gene expression posttranscriptionally by interfering with the stability and translation of messenger RNA molecules and are also known to cross-talk with other epigenetic mechanisms. In this review, we will summarize and discuss recent findings of alterations in miRNAs in tissues of patients with MDD and evidence of treatment-induced effects in these molecules.

CSF miR-16 expression and its association with miR-16 and serotonin transporter in the raphe of a rat model of depression

BACKGROUND

Depression is a common mental disorder with unknown mechanism. Emerging evidence shows that miRNAs play a critical role in the process of depression. Here we reported the cerebrospinal fluid (CSF) miR-16 expression and its association with miR-16 and serotonin transporter (SERT) in the raphe of a rat model of depression.

METHODS

20 rats were randomized to the control or CUMS (chronic unpredictable mild stress) group. The rats in the CUMS group underwent CUMS for 21 days, while those in the control group received no treatment. After anesthetization, CSF was collected for the measurement of miR-16. Then raphes from all rats were separated for determination of miR-16 and SERT protein.

RESULTS

The expression levels of miR-16 in CSF and raphe of the CUMS group were significantly lower than those of the control group (P = 0.007 and 0.031). However, SERT protein in raphe of the CUMS group was obviously increased as compared that of the control group (P = 0.005). There was a positive correlation between CSF miR-16 and raphe miR-16 (r = 0.95, P = 0.000). Meanwhile, negative correlations between miR-16 and SERT protein in raphe (r = -0.70 P = 0.02), between CSF miR-16 and raphe SERT protein (r = -0.86, P = 0.002) were observed in the CUMS group.

LIMITATIONS

We have not explored the reason why CSF miR-16 was decreased in the rat model of depression and only tested the association of miR-16 between CSF and raphe.

CONCLUSIONS

CSF miR-16 was involved in the pathogenesis of depression via reflecting raphe miR-16 level, and thus affecting raphe SERT expression.

Neuroplasticity, Neurotransmission and Brain-Related Genes in Major Depression and Bipolar Disorder: Focus on Treatment Outcomes in an Asiatic Sample

Introduction

Mood disorders are common and disabling disorders. Despite the availability of over 100 psychotropic compounds, only one-third of patients benefit from first-line treatments. Over the past 20 years, many studies have focused on the biological factors modulating disease risk and response to treatments, but with still inconclusive data. In order to improve our current knowledge, in this study, we investigated the role of a set of genes involved in different pathways (neurotransmission, neuroplasticity, circadian rhythms, transcription factors, signal transduction and cellular metabolism) in the treatment outcome of major depressive disorder (MDD) and bipolar disorder (BD) after naturalistic pharmacological treatment.

Methods

Totals of 242 MDD, 132 BD patients and 326 healthy controls of Asian ethnicity (Koreans) were genotyped for polymorphisms within 19 genes. Response and remission after 6–8 weeks of treatment with antidepressants and mood stabilizers were evaluated. In secondary analyses, genetic associations with disease risk and some disease-associated features (age of onset, suicide attempt and psychotic BD) were also tested.

Results

None of the variants within the investigated genes was significantly associated with treatment outcomes. Some marginal association (uncorrected p < 0.01) was observed for HTR2A, BDNF, CHL1, RORA and HOMER1 SNPs. In secondary analyses, HTR2A (rs643627, p = 0.002) and CHL1 (rs4003413, p = 0.002) were found associated with risk for BD, HOMER1 (rs6872497, p = 0.002) with lifetime history of suicide attempt in patients, and RORA with early onset and presence of psychotic features in BD. Marginal results were also observed for ST8SIA2 and COMT.

Discussion

Despite limitations linked to multiple testing on small samples, methodological shortcomings and small significance of the findings, this study may support the involvement of some candidate genes in the outcomes of treatments for mood disorders, as well as in BD risk and other disease features.

Electronic supplementary material

The online version of this article (10.1007/s12325-018-0781-2) contains supplementary material, which is available to authorized users.

Genistein Improves the Major Depression through Suppressing the Expression of miR-221/222 by Targeting Connexin 43

OBJECTIVE

Recent studies have indicated the possibility that genistein may improve depression via regulating the expression of miR221/222. This study is to explore whether genistein could improve depression by altering miR-221/222 levels and investigate the possible mechanisms involved in the improvement effect of genistein.

METHODS

The animal model of depression was established through unpredictable chronic mild stress. Nest building test and splash test were adapted to evaluate the effects of genistein on depressive symptoms in mice. qRT-PCR and western blot analysis were used to detect the expression of miR-221/222 and connexin 43 (Cx43) in the prefrontal cortex of the mice. In vitro, U87-MG astrocytes were treated with genistein and the expression of miR-221/222 and Cx43 was measured. The dual-luciferase reporter assay was used to verify whether Cx43 was a direct target of miR-221/222.

RESULTS

The behavioral tests showed that genistein could significantly reduce depression symptoms of mice, and this remission was not affected by gender. Genistein in vivo and in vitro could reduce increased levels of miR-221 and miR-222 in the prefrontal cortex of depressed mice, while upregulate Cx43 expression. Dual-luciferase reporter assay suggested Cx43 was directly regulated by miR-221/222 in astrocytes.

CONCLUSION

Genistein can play its antidepressant effect through down-regulating miR-221/222 by targeting Cx43.

SIRT1, miR-132 and miR-212 link human longevity to Alzheimer's Disease

Alzheimer's Disease (AD) is the most common cause of dementia in the elderly. Centenarians - reaching the age of >100 years while maintaining good cognitive skills - seemingly have unique biological features allowing healthy aging and protection from dementia. Here, we studied the expression of SIRT1 along with miR-132 and miR-212, two microRNAs known to regulate SIRT1, in lymphoblastoid cell lines (LCLs) from 45 healthy donors aged 21 to 105 years and 24 AD patients, and in postmortem olfactory bulb and hippocampus tissues from 14 AD patients and 20 age-matched non-demented individuals. We observed 4.0-fold (P = 0.001) lower expression of SIRT1, and correspondingly higher expression of miR-132 (1.7-fold; P = 0.014) and miR-212 (2.1-fold; P = 0.036), in LCLs from AD patients compared with age-matched healthy controls. Additionally, SIRT1 expression was 2.2-fold (P = 0.001) higher in centenarian LCLs compared with LCLs from individuals aged 56-82 years; while centenarian LCLs miR-132 and miR-212 indicated 7.6-fold and 4.1-fold lower expression, respectively. Correlations of SIRT1, miR-132 and miR-212 expression with cognitive scores were observed for AD patient-derived LCLs and postmortem AD olfactory bulb and hippocampus tissues, suggesting that higher SIRT1 expression, possibly mediated by lower miR-132 and miR-212, may protect aged individuals from dementia and is reflected in their peripheral tissues.

MicroRNA-451a, microRNA-34a-5p, and microRNA-221-3p as predictors of response to antidepressant treatment

Aberrant expression of microRNAs (miRNAs) has been shown to be involved in early observations of depression. The aim of this study was to determine if serum levels of miRNA-451a, miRNA-34a-5p, and miRNA-221-3p can serve as indicators of disease progression or therapeutic efficacy in depression. We collected data from 84 depressed patients and 78 control volunteers recruited from the medical staff at the West China Hospital. Depression severity was rated using the 24-item Hamilton Depression Scale (HAMD). Serum miRNA-451a, miRNA-34a-5p, and miRNA-221-3p levels were determined in samples from the depressed patients before and 8 weeks after antidepressant treatment as well as in samples from controls. Compared with the controls, the patients had lower miRNA-451a levels, higher miRNA-34a-5p and miRNA-221-3p levels, and increased HAMD scores whether they underwent antidepressant treatment or not. Eight weeks after antidepressant treatment, the patients exhibited increased miRNA-451a levels, decreased miRNA-34a-5p and miRNA-221-3p levels, and reduced HAMD scores. The serum level of miRNA-451a was negatively correlated with HAMD scores of the patients, while the serum levels of miRNA-34a-5p and miRNA-221-3p were positively correlated with HAMD scores whether the patients underwent antidepressant treatment or not. Paroxetine was markedly effective in 50 patients who also displayed an increased level of miRNA-451a but reduced levels of miRNA-34a-5p and miRNA-221-3p. In contrast, paroxetine was moderately effective or ineffective in 34 patients. In conclusion, depressed patients had lower serum miRNA-451a but higher serum miRNA-34a-5p and miRNA-221-3p, and these miRNAs are potential predictors of the efficacy of antidepressants.

MicroRNA-Mediated Regulation of ITGB3 and CHL1 Is Implicated in SSRI Action

Background: Selective serotonin reuptake inhibitor (SSRI) antidepressant drugs are the first-line of treatment for major depressive disorder (MDD) but are effective in <70% of patients. Our earlier genome-wide studies indicated that two genes encoding for cell adhesion proteins, close homolog of L1 (CHL1) and integrin beta-3 (ITGB3), and microRNAs, miR-151a-3p and miR-221/222, are implicated in the variable sensitivity and response of human lymphoblastoid cell lines (LCL) from unrelated individuals to SSRI drugs.

Methods: The microRNAs miR-221, miR-222, and miR-151-a-3p, along with their target gene binding sites, were explored in silico using miRBase, TargetScan, microRNAviewer, and the UCSC Genome Browser. Luciferase reporter assays were conducted for demonstrating the direct functional regulation of ITGB3 and CHL1 expression by miR-221/222 and miR-151a-3p, respectively. A human LCL exhibiting low sensitivity to paroxetine was utilized for studying the phenotypic effect of CHL1 regulation by miR-151a-3p on SSRI response.

Results: By showing direct regulation of CHL1 and ITGB3 by miR-151a-3p and miR-221/222, respectively, we link these microRNAs and genes with cellular SSRI sensitivity phenotypes. We report that miR-151a-3p increases cell sensitivity to paroxetine via down-regulating CHL1 expression.

Conclusions: miR-151a-3p, miR-221/222 and their (here confirmed) respective target-genes, CHL1 and ITGB3, are implicated in SSRI responsiveness, and possibly in the clinical response to antidepressant drugs.

The Gain-of-Function Integrin β3 Pro33 Variant Alters the Serotonin System in the Mouse Brain

Engagement of integrins by the extracellular matrix initiates signaling cascades that drive a variety of cellular functions, including neuronal migration and axonal pathfinding in the brain. Multiple lines of evidence link the ITGB3 gene encoding the integrin β3 subunit with the serotonin (5-HT) system, likely via its modulation of the 5-HT transporter (SERT). The ITGB3 coding polymorphism Leu33Pro (rs5918, Pl^A2) produces hyperactive αvβ3 receptors that influence whole-blood 5-HT levels and may influence the risk for autism spectrum disorder (ASD). Using a phenome-wide scan of psychiatric diagnoses, we found significant, male-specific associations between the Pro33 allele and attention-deficit hyperactivity disorder and ASDs. Here, we used knock-in (KI) mice expressing an Itgb3 variant that phenocopies the human Pro33 variant to elucidate the consequences of constitutively enhanced αvβ3 signaling to the 5-HT system in the brain. KI mice displayed deficits in multiple behaviors, including anxiety, repetitive, and social behaviors. Anatomical studies revealed a significant decrease in 5-HT synapses in the midbrain, accompanied by decreases in SERT activity and reduced localization of SERTs to integrin adhesion complexes in synapses of KI mice. Inhibition of focal adhesion kinase (FAK) rescued SERT function in synapses of KI mice, demonstrating that constitutive active FAK signaling downstream of the Pro32Pro33 integrin αvβ3 suppresses SERT activity. Our studies identify a complex regulation of 5-HT homeostasis and behaviors by integrin αvβ3, revealing an important role for integrins in modulating risk for neuropsychiatric disorders.SIGNIFICANCE STATEMENT The integrin β3 Leu33Pro coding polymorphism has been associated with autism spectrum disorders (ASDs) within a subgroup of patients with elevated blood 5-HT levels, linking integrin β3, 5-HT, and ASD risk. We capitalized on these interactions to demonstrate that the Pro33 coding variation in the murine integrin β3 recapitulates the sex-dependent neurochemical and behavioral attributes of ASD. Using state-of-the-art techniques, we show that presynaptic 5-HT function is altered in these mice, and that the localization of 5-HT transporters to specific compartments within the synapse, disrupted by the integrin β3 Pro33 mutation, is critical for appropriate reuptake of 5-HT. Our studies provide fundamental insight into the genetic network regulating 5-HT neurotransmission in the CNS that is also associated with ASD risk.

Precision medicine for suicidality: from universality to subtypes and personalization

Suicide remains a clear, present and increasing public health problem, despite being a potentially preventable tragedy. Its incidence is particularly high in people with overt or un(der)diagnosed psychiatric disorders. Objective and precise identification of individuals at risk, ways of monitoring response to treatments and novel preventive therapeutics need to be discovered, employed and widely deployed. We sought to investigate whether blood gene expression biomarkers for suicide (that is, a 'liquid biopsy' approach) can be identified that are more universal in nature, working across psychiatric diagnoses and genders, using larger cohorts than in previous studies. Such markers may reflect and/or be a proxy for the core biology of suicide. We were successful in this endeavor, using a comprehensive stepwise approach, leading to a wealth of findings. Steps 1, 2 and 3 were discovery, prioritization and validation for tracking suicidality, resulting in a Top Dozen list of candidate biomarkers comprising the top biomarkers from each step, as well as a larger list of 148 candidate biomarkers that survived Bonferroni correction in the validation step. Step 4 was testing the Top Dozen list and Bonferroni biomarker list for predictive ability for suicidal ideation (SI) and for future hospitalizations for suicidality in independent cohorts, leading to the identification of completely novel predictive biomarkers (such as CLN5 and AK2), as well as reinforcement of ours and others previous findings in the field (such as SLC4A4 and SKA2). Additionally, we examined whether subtypes of suicidality can be identified based on mental state at the time of high SI and identified four potential subtypes: high anxiety, low mood, combined and non-affective (psychotic). Such subtypes may delineate groups of individuals that are more homogenous in terms of suicidality biology and behavior. We also studied a more personalized approach, by psychiatric diagnosis and gender, with a focus on bipolar males, the highest risk group. Such a personalized approach may be more sensitive to gender differences and to the impact of psychiatric co-morbidities and medications. We compared testing the universal biomarkers in everybody versus testing by subtypes versus personalized by gender and diagnosis, and show that the subtype and personalized approaches permit enhanced precision of predictions for different universal biomarkers. In particular, LHFP appears to be a strong predictor for suicidality in males with depression. We also directly examined whether biomarkers discovered using male bipolars only are better predictors in a male bipolar independent cohort than universal biomarkers and show evidence for a possible advantage of personalization. We identified completely novel biomarkers (such as SPTBN1 and C7orf73), and reinforced previously known biomarkers (such as PTEN and SAT1). For diagnostic ability testing purposes, we also examined as predictors phenotypic measures as apps (for suicide risk (CFI-S, Convergent Functional Information for Suicidality) and for anxiety and mood (SASS, Simplified Affective State Scale)) by themselves, as well as in combination with the top biomarkers (the combination being our a priori primary endpoint), to provide context and enhance precision of predictions. We obtained area under the curves of 90% for SI and 77% for future hospitalizations in independent cohorts. Step 5 was to look for mechanistic understanding, starting with examining evidence for the Top Dozen and Bonferroni biomarkers for involvement in other psychiatric and non-psychiatric disorders, as a mechanism for biological predisposition and vulnerability. The biomarkers we identified also provide a window towards understanding the biology of suicide, implicating biological pathways related to neurogenesis, programmed cell death and insulin signaling from the universal biomarkers, as well as mTOR signaling from the male bipolar biomarkers. In particular, HTR2A increase coupled with ARRB1 and GSK3B decreases in expression in suicidality may provide a synergistic mechanistical corrective target, as do SLC4A4 increase coupled with AHCYL1 and AHCYL2 decrease. Step 6 was to move beyond diagnostics and mechanistical risk assessment, towards providing a foundation for personalized therapeutics. Items scored positive in the CFI-S and subtypes identified by SASS in different individuals provide targets for personalized (psycho)therapy. Some individual biomarkers are targets of existing drugs used to treat mood disorders and suicidality (lithium, clozapine and omega-3 fatty acids), providing a means toward pharmacogenomics stratification of patients and monitoring of response to treatment. Such biomarkers merit evaluation in clinical trials. Bioinformatics drug repurposing analyses with the gene expression biosignatures of the Top Dozen and Bonferroni-validated universal biomarkers identified novel potential therapeutics for suicidality, such as ebselen (a lithium mimetic), piracetam (a nootropic), chlorogenic acid (a polyphenol) and metformin (an antidiabetic and possible longevity promoting drug). Finally, based on the totality of our data and of the evidence in the field to date, a convergent functional evidence score prioritizing biomarkers that have all around evidence (track suicidality, predict it, are reflective of biological predisposition and are potential drug targets) brought to the fore APOE and IL6 from among the universal biomarkers, suggesting an inflammatory/accelerated aging component that may be a targetable common denominator.

Human iPSC-derived neurons and lymphoblastoid cells for personalized medicine research in neuropsychiatric disorders

The development and clinical implementation of personalized medicine crucially depends on the availability of high-quality human biosamples; animal models, although capable of modeling complex human diseases, cannot reflect the large variation in the human genome, epigenome, transcriptome, proteome, and metabolome. Although the biosamples available from public biobanks that store human tissues and cells may represent the large human diversity for most diseases, these samples are not always sufficient for developing biomarkers for patient-tailored therapies for neuropsychiatric disorders. Postmortem human tissues are available from many biobanks; nevertheless, collections of neuronal human cells from large patient cohorts representing the human diversity remain scarce. Two tools are gaining popularity for personalized medicine research on neuropsychiatric disorders: human induced pluripotent stem cell-derived neurons and human lymphoblastoid cell lines. This review examines and contrasts the advantages and limitations of each tool for personalized medicine research.

Premature primary tooth eruption in cognitive/motor-delayed ADNP-mutated children

A major flaw in autism spectrum disorder (ASD) management is late diagnosis. Activity-dependent neuroprotective protein (ADNP) is a most frequent de novo mutated ASD-related gene. Functionally, ADNP protects nerve cells against electrical blockade. In mice, complete Adnp deficiency results in dysregulation of over 400 genes and failure to form a brain. Adnp haploinsufficiency results in cognitive and social deficiencies coupled to sex- and age-dependent deficits in the key microtubule and ion channel pathways. Here, collaborating with parents/caregivers globally, we discovered premature tooth eruption as a potential early diagnostic biomarker for ADNP mutation. The parents of 44/54 ADNP-mutated children reported an almost full erupted dentition by 1 year of age, including molars and only 10 of the children had teeth within the normal developmental time range. Looking at Adnp-deficient mice, by computed tomography, showed significantly smaller dental sacs and tooth buds at 5 days of age in the deficient mice compared to littermate controls. There was only trending at 2 days, implicating age-dependent dysregulation of teething in Adnp-deficient mice. Allen Atlas analysis showed Adnp expression in the jaw area. RNA sequencing (RNAseq) and gene array analysis of human ADNP-mutated lymphoblastoids, whole-mouse embryos and mouse brains identified dysregulation of bone/nervous system-controlling genes resulting from ADNP mutation/deficiency (for example, BMP1 and BMP4). AKAP6, discovered here as a major gene regulated by ADNP, also links cognition and bone maintenance. To the best of our knowledge, this is the first time that early primary (deciduous) teething is related to the ADNP syndrome, providing for early/simple diagnosis and paving the path to early intervention/specialized treatment plan.

Proliferation rates and gene expression profiles in human lymphoblastoid cell lines from patients with depression characterized in response to antidepressant drug therapy

The current therapy success of depressive disorders remains in need of improvement due to low response rates and a delay in symptomatic improvement. Reliable functional biomarkers would be necessary to predict the individual treatment outcome. On the basis of the neurotrophic hypothesis of antidepressant's action, effects of antidepressant drugs on proliferation may serve as tentative individual markers for treatment efficacy. We studied individual differences in antidepressant drug effects on cell proliferation and gene expression in lymphoblastoid cell lines (LCLs) derived from patients treated for depression with documented clinical treatment outcome. Cell proliferation was characterized by EdU (5-ethynyl-2'-deoxyuridine) incorporation assays following a 3-week incubation with therapeutic concentrations of fluoxetine. Genome-wide expression profiling was conducted by microarrays, and candidate genes such as betacellulin-a gene involved in neuronal stem cell regeneration-were validated by quantitative real-time PCR. Ex vivo assessment of proliferation revealed large differences in fluoxetine-induced proliferation inhibition between donor LCLs, but no association with clinical response was observed. Genome-wide expression analyses followed by pathway and gene ontology analyses identified genes with different expression before vs after 21-day incubation with fluoxetine. Significant correlations between proliferation and gene expression of WNT2B, FZD7, TCF7L2, SULT4A1 and ABCB1 (all involved in neurogenesis or brain protection) were also found. Basal gene expression of SULT4A1 (P=0.029), and gene expression fold changes of WNT2B by ex vivo fluoxetine (P=0.025) correlated with clinical response and clinical remission, respectively. Thus, we identified potential gene expression biomarkers eventually being useful as baseline predictors or as longitudinal targets in antidepressant therapy.

RGS2 expression predicts amyloid-β sensitivity, MCI and Alzheimer's disease: genome-wide transcriptomic profiling and bioinformatics data mining

Alzheimer's disease (AD) is the most frequent cause of dementia. Misfolded protein pathological hallmarks of AD are brain deposits of amyloid-β (Aβ) plaques and phosphorylated tau neurofibrillary tangles. However, doubts about the role of Aβ in AD pathology have been raised as Aβ is a common component of extracellular brain deposits found, also by in vivo imaging, in non-demented aged individuals. It has been suggested that some individuals are more prone to Aβ neurotoxicity and hence more likely to develop AD when aging brains start accumulating Aβ plaques. Here, we applied genome-wide transcriptomic profiling of lymphoblastoid cells lines (LCLs) from healthy individuals and AD patients for identifying genes that predict sensitivity to Aβ. Real-time PCR validation identified 3.78-fold lower expression of RGS2 (regulator of G-protein signaling 2; P=0.0085) in LCLs from healthy individuals exhibiting high vs low Aβ sensitivity. Furthermore, RGS2 showed 3.3-fold lower expression (P=0.0008) in AD LCLs compared with controls. Notably, RGS2 expression in AD LCLs correlated with the patients' cognitive function. Lower RGS2 expression levels were also discovered in published expression data sets from postmortem AD brain tissues as well as in mild cognitive impairment and AD blood samples compared with controls. In conclusion, Aβ sensitivity phenotyping followed by transcriptomic profiling and published patient data mining identified reduced peripheral and brain expression levels of RGS2, a key regulator of G-protein-coupled receptor signaling and neuronal plasticity. RGS2 is suggested as a novel AD biomarker (alongside other genes) toward early AD detection and future disease modifying therapeutics.

Circulating Plasma Micro RNAs in Patients with Major Depressive Disorder Treated with Antidepressants: A Pilot Study

OBJECTIVE

Significant progress was made in the understanding etiopathogenic factors related to MDD, including through research on the role of micro RNAs (miRs). We investigated plasma miRs as potential markers for MDD in patients treated with antidepressants.

METHODS

At the initiation and at the end of twelve weeks of treatment, blood samples were collected and a structured diagnostic interview and a standardized depression rating scale for the presence and severity of major depression were done. The average decrease in HAMD score was 76.89%. Plasma miR expression profiling was performed by real time PCR. The lists of up-regulated (cut-off=2) and down-regulated miRs were imported into the miRWalk2.0 algorithm and used for target predictions. KEGG database pathways analysis was used to retrieve the pathways significantly targeted by at least two of the miRs.

RESULTS

Of the 222 miRs detected in plasma samples of MDD patients, 40 were differentially expressed after treatment. Twenty-three miRs were significantly overexpressed with fold changes between 1.85 and 25.42, and 17 miRs were significantly downregulated with fold changes from 0.28 to 0.68. Pathway analysis revealed a list of 29 pathways for up-regulated miRs, and 20 pathways for down-regulated miRs. Six dysregulated miRs are common to all the top five pathways (Wnt signaling, Cancer, Endocytosis, Axon guidance, MAPK signaling): miR-146a-5p, miR-146b-5p, miR-221-3p, miR-24-3p, miR-26a-5p.

CONCLUSION

Overall, our miRWalk analysis of changes in plasma microRNAs after treatment of patients with major depression might open a new avenue for the understanding of Escitalopram mode of action and for its side effects.

Decreased sensitivity to paroxetine-induced inhibition of peripheral blood mononuclear cell growth in depressed and antidepressant treatment-resistant patients

Major depression disorder (MDD) is the most widespread mental disorder. Selective serotonin reuptake inhibitors (SSRIs) are used as first-line MDD treatment but are effective in <70% of patients. Thus, biomarkers for the early identification of treatment-resistant (TR) MDD patients are needed for prioritizing them for alternative therapeutics. SSRI-induced inhibition of the growth of peripheral blood mononuclear cells (PBMCs) is mediated via their target, the serotonin transporter (SERT). Here, we examined whether antidepressant drug-induced inhibition of the growth of PBMCs differed between MDD patients and healthy controls. PBMCs from well-characterized 33 treatment-sensitive (TS) and 33 TR MDD patients, and 24 healthy volunteers were studied. Dose-dependent inhibition of PBMCs growth was observed for both the non-SSRI antidepressant mirtazapine and the SSRI antidepressant paroxetine. Significantly lower sensitivities to 20 μm paroxetine were observed in MDD compared with control PBMCs prior to treatment onset (13% and 46%, respectively; P<0.05). Following antidepressant drug treatment for 4 or 7 weeks, the ex vivo paroxetine sensitivity increased to control levels in PBMCs from TS but not from TR MDD patients. This suggests that the low ex vivo paroxetine sensitivity phenotype reflects a state marker of depression. A significantly lower expression of integrin beta-3 (ITGB3), a co-factor of the SERT, was observed in the PBMCs of MDD patients prior to treatment onset compared with healthy controls, and may explain their lower paroxetine sensitivity. Further studies with larger cohorts are required for clarifying the potential of reduced PBMCs paroxetine sensitivity and lower ITGB3 expression as MDD biomarkers.

The MiRNA Journey from Theory to Practice as a CNS Biomarker

MicroRNAs (miRNAs), small nucleotide sequences that control gene transcription, have the potential to serve an expanded function as indicators in the diagnosis and progression of neurological disorders. Studies involving debilitating neurological diseases such as, Alzheimer's disease, multiple sclerosis, traumatic brain injuries, Parkinson's disease and CNS tumors, already provide validation for their clinical diagnostic use. These small nucleotide sequences have several features, making them favorable candidates as biomarkers, including function in multiple tissues, stability in bodily fluids, a role in pathogenesis, and the ability to be detected early in the disease course. Cerebrospinal fluid, with its cell-free environment, collection process that minimizes tissue damage, and direct contact with the brain and spinal cord, is a promising source of miRNA in the diagnosis of many neurological disorders. Despite the advantages of miRNA analysis, current analytic technology is not yet affordable as a clinically viable diagnostic tool and requires standardization. The goal of this review is to explore the prospective use of CSF miRNA as a reliable and affordable biomarker for different neurological disorders.

Genome-wide microarray analysis of gene expression profiling in major depression and antidepressant therapy

Major depressive disorder (MDD) is a serious health concern worldwide. Currently there are no predictive tests for the effectiveness of any particular antidepressant in an individual patient. Thus, doctors must prescribe antidepressants based on educated guesses. With the recent advent of scientific research, genome-wide gene expression microarray studies are widely utilized to analyze hundreds of thousands of biomarkers by high-throughput technologies. In addition to the candidate-gene approach, the genome-wide approach has recently been employed to investigate the determinants of MDD as well as antidepressant response to therapy. In this review, we mainly focused on gene expression studies with genome-wide approaches using RNA derived from peripheral blood cells. Furthermore, we reviewed their limitations and future directions with respect to the genome-wide gene expression profiling in MDD pathogenesis as well as in antidepressant therapy.

Targeting drug sensitivity predictors: New potential strategies to improve pharmacotherapy of human brain disorders

One of the main challenges in medicine is the lack of efficient drug therapies for common human disorders. For example, although depressed patients receive powerful antidepressants, many often remain resistant to psychopharmacotherapy. The growing recognition of complex interplay between the drug targets and the predictors of drug sensitivity requires an improved understanding of these two key aspects of drug action and their potentially shared molecular networks. Here, we apply the concept of endophenotypes and their interplay to drug action and sensitivity. Based on these analyses, we postulate that novel drugs may be developed by targeting specific molecular pathways that integrate drug targets with drug sensitivity predictors.

miRNAs and other non-coding RNAs in posttraumatic stress disorder: A systematic review of clinical and animal studies

In the last couple of years, non-coding (nc) RNAs like micro-RNAs (miRNAs), small interference RNAs (siRNAs) and long ncRNAs (lncRNAs) have emerged as promising candidates for biomarkers and drug-targets in a variety of psychiatric disorders. In contrast to reports on ncRNAs in affective disorders, schizophrenia and anxiety disorders, manuscripts on ncRNAs in posttraumatic stress disorder (PTSD) and associated animal models are scarce. Aiming to stimulate ncRNA research in PTSD and to identify the hitherto most promising ncRNA candidates and associated pathways for psychotrauma research, we conducted the first review on ncRNAs in PTSD. We aimed to identify studies reporting on the expression, function and regulation of ncRNAs in PTSD patients and in animals exhibiting a PTSD-like syndrome. Following the PRISMA guidelines for systematic reviews, we systematically screened the PubMed database for clinical and animal studies on ncRNAs in PTSD, animal models for PTSD and animal models employing a classical fear conditioning paradigm. Using 112 different combinations of search terms, we retrieved 523 articles of which we finally included and evaluated three clinical and 12 animal studies. In addition, using the web-based tool DIANA miRPath v2.0, we searched for molecular pathways shared by the predicted targets of the here-evaluated miRNA candidates. Our findings suggest that mir-132, which has been found to be regulated in three of the here included studies, as well as miRNAs with an already established role in Alzheimer's disease (AD) seem to be particularly promising candidates for future miRNA studies in PTSD. These results are limited by the low number of human trials and by the heterogeneity of included animal studies.

Mice lacking integrin β3 expression exhibit altered response to chronic stress

Recent studies indicate multiple roles for integrin αvβ3 in adult neurons, including response to pharmacological agents such as cocaine and selective serotonin reuptake inhibitors. In this study, we examined the role of the integrin β3 gene (Itgb3) in the response to environmental stimuli by subjecting Itgb3^+/+ and Itgb3^-/- mice to unpredictable chronic mild stressors. We found that genetic abrogation of integrin β3 expression elicits an exaggerated vulnerability to chronic unpredictable stress in the open field test. In this test, chronic stress elicited significant decreases in stereotypic behavior and horizontal locomotor activity, including increases in anxiety behaviors. Mild chronic stress led to reductions in dopamine turnover in midbrains of Itgb3^+/+, but not Itgb3^-/- mice, suggesting a disruption of stress-dependent regulation of DA homeostasis. Chronic stress elicited altered synaptic expression of syntaxin and synaptophysin in midbrains of Itgb3^-/- mice, when compared to Itgb3^+/+. Semi-quantitative Western blot studies revealed that the synaptic expression, but not total tissue expression, of multiple signaling proteins is correlated with integrin αv levels in the midbrain. Moreover, loss of integrin β3 expression modifies this correlation network. Together, these findings demonstrate that Itgb3^-/- mice display a pattern of changes indicating disrupted regulation of midbrain synaptic systems involved in conferring resilience to mild stressors.

CHL1, ITGB3 and SLC6A4 gene expression and antidepressant drug response: results from the Munich Antidepressant Response Signature (MARS) study

Aim: The identification of antidepressant drugs (ADs) response biomarkers in depression is of high clinical importance. We explored CHL1 and ITGB3 expression as tentative response biomarkers. Materials & methods: In vitro sensitivity to ADs, as well as gene expression and genetic variants of the candidate genes CHL1, ITGB3 and SLC6A4 were measured in lymphoblastoid cell lines (LCLs) of 58 depressed patients. Results: An association between the clinical remission of depression and the basal expression of CHL1 and ITGB3 was discovered. Individuals whose LCLs expressed higher levels of CHL1 or ITGB3 showed a significantly better remission upon AD treatment. In addition individuals with the CHL1 rs1516338 TT genotype showed a significantly better remission after 5 weeks AD treatment than those carrying a CC genotype. No association between the in vitro sensitivity of LCLs toward AD and the clinical remission could be detected. Conclusion: CHL1 expression in patient-derived LCLs correlated with the clinical outcome. Thus, it could be a valid biomarker to predict the success of an antidepressant therapy.

Original submitted 8 December 2014; Revision submitted 2 March 2015

Neuronal cell adhesion genes and antidepressant response in three independent samples

Drug-effect phenotypes in human lymphoblastoid cell lines recently allowed to identify CHL1 (cell adhesion molecule with homology to L1CAM), GAP43 (growth-associated protein 43) and ITGB3 (integrin beta 3) as new candidates for involvement in the antidepressant effect. CHL1 and ITGB3 code for adhesion molecules, while GAP43 codes for a neuron-specific cytosolic protein expressed in neuronal growth cones; all the three gene products are involved in synaptic plasticity. Sixteen polymorphisms in these genes were genotyped in two samples (n=369 and 90) with diagnosis of major depressive episode who were treated with antidepressants in a naturalistic setting. Phenotypes were response, remission and treatment-resistant depression. Logistic regression including appropriate covariates was performed. Genes associated with outcomes were investigated in the Sequenced Treatment Alternatives to Relieve Depression (STAR*D) genome-wide study (n=1861) as both individual genes and through a pathway analysis (Reactome and String databases). Gene-based analysis suggested CHL1 rs4003413, GAP43 rs283393 and rs9860828, ITGB3 rs3809865 as the top candidates due to their replication across the largest original sample and the STAR*D cohort. GAP43 molecular pathway was associated with both response and remission in the STAR*D, with ELAVL4 representing the gene with the highest percentage of single nucleotide polymorphisms (SNPs) associated with outcomes. Other promising genes emerging from the pathway analysis were ITGB1 and NRP1. The present study was the first to analyze cell adhesion genes and their molecular pathways in antidepressant response. Genes and biomarkers involved in neuronal adhesion should be considered by further studies aimed to identify predictors of antidepressant response.

Identification of differential microRNAs in cerebrospinal fluid and serum of patients with major depressive disorder

Major depression is a debilitating disease. To date, the development of biomarkers of major depressive disorder (MDD) remains a challenge. Recently, alterations in the expression of microRNAs (miRNAs) from post-mortem brain tissue and peripheral blood have been linked to MDD. The goals of this study were to detect the differential miRNAs in cerebrospinal fluid (CSF) and serum of MDD patients. First, the relative expression levels of 179 miRNAs (relative high levels in serum) were analyzed by miRNA PCR Panel in the CSF of MDD patients. Then, the differentially altered miRNAs from CSF were further assessed by qRT-PCR in the serum of the same patients. Finally, the serum differentially altered miRNAs were further validated by qRT-PCR in the serum of another MDD patients. The CSF-results indicated that 11 miRNAs in MDD patients were significantly higher than these in control subjects, and 5 miRNAs were significantly lower than these in control subjects. The serum-results from the same patients showed that 3 miRNAs (miR-221-3p, miR-34a-5p, and let-7d-3p) of the 11 miRNAs were significantly higher than these in control subjects, and 1 miRNA (miR-451a) of 5 miRNAs was significantly lower than these in control subjects. The up-regulation of miR-221-3p, miR-34a-5p, let-7d-3p and down-regulation of miR-451a was further validated in another 32 MDD patients. ROC analysis showed that the area under curve of let-7d-3p, miR-34a-5p, miR-221-3p and miR-451a was 0.94, 0.98, 0.97 and 0.94, with specificity of 90.48%, 95.24%, 90.48% and 90.48%, and sensitivity of 93.75%, 96.88%, 90.63% and 84.85%, respectively. In addition, target gene prediction found that the altered miRNAs are involved in affecting some important genes and pathway related to MDD. Our results suggested that differentially altered miRNAs in CSF might be involved in MDD, and serum miR-221-3p, miR-34a-5p, let-7d-3p, and miR-451a might be able to serve as biomarkers for MDD.