Comparison of plasma MicroRNA levels in drug naive, first episode depressed patients and healthy controls

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.

Resilient Phenotype in Chronic Mild Stress Paradigm Is Associated with Altered Expression Levels of miR-18a-5p and Serotonin 5-HT1a Receptor in Dorsal Part of the Hippocampus

Disturbed serotonergic signaling in the hippocampus observed in many individuals vulnerable to stress has been suggested as one of the primary factors contributing to the development of depression. However, little is known about the physiology of the brain in the resilient phenotype. Resilient subjects maintain a positive mood and psychological balance despite being under the stress influence. In our study, we generated stress-vulnerable and resilient rats by using a chronic mild stress (CMS) paradigm. Using different molecular approaches, we revealed that resilient animals exhibited a significantly decreased expression level of miR-18a-5p and, in the same time, an elevated level of 5-HT1AR in dorsal, but not ventral, part of the hippocampus. Described biochemical changes were not observed in animals behaviorally vulnerable to stress. Further, in vitro analysis showed that miR-18a-5p may be a negative epigenetic regulator of 5-HT1AR since the treatment of adult hippocampal neurons with miR-18a-5p mimic significantly lowered the expression level of mRNA encoding 5-HT1AR. Moreover, bioinformatic analysis of potential target genes expressed in the hippocampus and being regulated by miR-18a-5p showed that this microRNA may regulate biological processes, such as axonogenesis, which are important in the functioning of the hippocampus in both rats and humans. All these molecular features may contribute to serotonergic homeostatic balance at the level of serotonin turnover observed in hippocampi of resilient but not stress-vulnerable rats. Delineation of further molecular and biochemical markers underlying resilience to stress may contribute to the development of new antidepressant strategies which will restore resilient phenotype in depressed patients.

The Missing Link: How Exosomes and miRNAs can Help in Bridging Psychiatry and Molecular Biology in the Context of Depression, Bipolar Disorder and Schizophrenia

MicroRNAs (miRNAs) only recently have been recognized as promising molecules for both fundamental and clinical neuroscience. We provide a literature review of miRNA biomarker studies in three most prominent psychiatric disorders (depression, bipolar disorder and schizophrenia) with the particular focus on depression due to its social and healthcare importance. Our search resulted in 191 unique miRNAs across 35 human studies measuring miRNA levels in blood, serum or plasma. 30 miRNAs replicated in more than one study. Most miRNAs targeted neuroplasticity and neurodevelopment pathways. Various limitations do not allow us to make firm conclusions on clinical potential of studied miRNAs. Based on our results we discuss the rationale for future research investigations of exosomal mechanisms to overcome methodological caveats both in studying etiology and pathogenesis, and providing an objective back-up for clinical decisions.

Plasma microRNA expression levels and their targeted pathways in patients with major depressive disorder who are responsive to duloxetine treatment

Major depressive disorder (MDD) is a complex disorder with many pathways known to contribute to its pathogenesis, such as apoptotic signaling, with antidepressants having been shown to target these pathways. In this study, we explored microRNAs as predictive markers of drug response to duloxetine, a serotonin-norepinephrine reuptake inhibiter, using peripheral blood samples from 3 independent clinical trials (NCT00635219; NCT0059991; NCT01140906) comparing 6-8 weeks of treatment with duloxetine to placebo treatment in patients with MDD. Plasma microRNA was extracted and sequenced using the Ion Proton Sequencer. Rank feature selection analysis was used to identify microRNAs in the top 10th percentile for their differentiating ability between patients who remitted and did not remit with duloxetine treatment. The results were then compared between the 3 trials to see their replicability. To further validate our findings, we reasoned that the pathways targeted by these microRNAs would be those shown to be altered in MDD in pathway enrichment analysis. Hsa-miR-23a-3p, hsa-miR-16-5p, hsa-miR-146a-5p and hsa-miR-21-5p were identified in 2 or more trials as being able to differentiate patients who would remit with duloxetine treatment using samples collected before treatment initiation, suggesting that they may be good candidates for identification of predictive biomarkers of duloxetine response. Pathway enrichment analysis further showed that microRNAs identified as differentiating for duloxetine response target the apoptosis signaling pathway. Future studies examining these microRNAs outside of a clinical trial setting and exploring their role in MDD may further our understanding of MDD and antidepressant response.

Roles of PI3K/AKT/GSK3 Pathway Involved in Psychiatric Illnesses

Psychiatric illnesses may be qualified to the cellular impairments of the function for survival or death in neurons, which may consequently appear as abnormalities in the neuroplasticity. The molecular mechanism has not been well understood, however, it seems that PI3K, AKT, GSK3, and their downstream molecules have crucial roles in the pathogenesis. Through transducing cell surviving signal, the PI3K/AKT/GSK3 pathway may organize an intracellular central network for the action of the synaptic neuroplasticity. In addition, the pathways may also regulate cell proliferation, cell migration, and apoptosis. Several lines of evidence have supported a role for this signaling network underlying the development and treatment for psychiatric illnesses. Indeed, the discovery of molecular biochemical phenotypes would represent a breakthrough in the research for effective treatment. In this review, we summarize advances on the involvement of the PI3K/AKT/GSK3 pathways in cell signaling of neuronal cells. This study may provide novel insights on the mechanism of mental disorder involved in psychiatric illnesses and would open future opportunity for contributions suggesting new targets for diagnostic and/or therapeutic procedures.

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.

MiR-221 is involved in depression by regulating Wnt2/CREB/BDNF axis in hippocampal neurons

OBJECTIVE

The aim of this study was to investigate the mechanism of miR-221 in depression.

METHODS

The molecules expressions were measured by qRT-PCR and western blot. The sucrose preference test (SPT), forced swimming test (FST) and tail suspension test (TST) were used to detect depressive-like symptoms. MTT assay and flow cytometric was used to measure the proliferation and apoptosis of hippocampal neuronal.

RESULTS

MiR-221 expression in the cerebrospinal fluid and serum of major depressive disorder patients and the hippocampus of chronic unpredictable mild stress (CUMS) mice were increased, while the expression of Wnt2, p-CREB and BDNF were decreased. Additionally, silence of miR-221 increased sucrose preference of CUMS mice and shortened the immobility time of CUMS mice in SPT and FST. MiR-221 could targeted regulate Wnt2, and knockdown of Wnt2 reversed the effect of miR-221 inhibitor on the proliferation and apoptosis of hippocampal neurons and countered the promoting effect of miR-221 inhibitor on the expression of Wnt2, p-CREB and BDNF.

CONCLUSION

MiR-221 could promote the development of depression by regulating Wnt2/CREB/BDNF axis.

Circulating microRNAs as biomarkers for depression: Many candidates, few finalists

BACKGROUND

Recent research has highlighted the potential of microRNAs to serve as physiological indicators of disease process among clinically depressed patients.

METHODS

In a comprehensive literature search through PubMed, we identified 23 articles comparing circulating (blood, plasma, or serum) microRNA expression levels in depressed versus healthy human subjects. Six studies examining circulatory microRNA expression through animal models of depression were also identified through the search and details of each study were outlined. A meta-analytic evaluation of these studies was not considered feasible, given the absence of concordance in the literature to date.

RESULTS

A total of 178 specific microRNA candidates were identified in the human studies as significantly expressed among depressed samples. Ninety-seven of these microRNAs were upregulated, 75 were downregulated, and 6 showed mixed expression in depressed samples. Few microRNAs were consistently expressed across studies; the most consistent evidence was for microRNA-132, with replication in 4 different studies. Among animal studies, 2 studies investigated microRNA-16 through distinct stress-induced depression models.

LIMITATIONS

Structural variations in microRNA sequences, methodological inconsistencies in technology used among studies to measure microRNA expression levels, differences in the clinical severity and forms of depression among subjects, and the overall paucity of studies make it difficult to ascertain any robust, preliminary targets deserving of biomarker potential.

CONCLUSIONS

Ongoing research needs to address this high rate of non-replication as well as the methodological and reporting challenges of microRNA experimentation in order to determine valid effect sizes for the more proliferative candidates associated with depression.

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.

Elevated serum levels of malondialdehyde and cortisol are associated with major depressive disorder: A case-control study

Objectives:

Major depressive disorder is diagnosed on the basis of patient’s self-reported experiences, behavior reported by relatives, and a mental status examination, and yet we do not have any reliable biomarker for this. Mood-regulating pathways are affected by oxidative injury to lipids and cortisol is released into the blood due to stimulation of corticotrophin receptors in the adrenal cortex. Here, we aimed to determine serum levels of malondialdehyde and cortisol in major depressive disorder patients and controls.

Methods:

We collected blood samples from 247 major depressive disorder patients and 248 controls. Serum levels of malondialdehyde and cortisol were measured by ultraviolet spectrophotometry and enzyme-linked immunosorbent assay kit, respectively.

Results:

We found malondialdehyde levels were significantly higher in patients than controls, with mean ± standard deviation at 4.49 ± 1.37 and 2.87 ± 0.82 µmol/L, respectively, p < 0.001. Cortisol levels were also found significantly higher in patients than controls, with mean ± SD at 19.22 ± 1.64 and 17.37 ± 1.34 µg/dL, respectively, p < 0.001. Significant negative correlation was observed between serum levels of malondialdehyde and cortisol in patients (r =−0.170, p = 0.021). Receiver operating characteristic analysis showed good diagnostic value for malondialdehyde and cortisol, with the area under the curve at 0.853 and 0.819, respectively.

Conclusion:

The present study suggests that increased serum levels of malondialdehyde and cortisol are strongly associated with major depressive disorder. We believe elevations of malondialdehyde and cortisol in serum level arise independently and they could serve as biomarkers for major depressive disorder.

The Role of MicroRNAs in Environmental Risk Factors, Noise-Induced Hearing Loss, and Mental Stress

SIGNIFICANCE

MicroRNAs (miRNAs) are important regulators of gene expression and define part of the epigenetic signature. Their influence on every realm of biomedicine is established and progressively increasing. The impact of environment on human health is enormous. Among environmental risk factors impinging on quality of life are those of chemical nature (toxic chemicals, heavy metals, pollutants, and pesticides) as well as those related to everyday life such as exposure to noise or mental and psychosocial stress. Recent Advances: This review elaborates on the relationship between miRNAs and these environmental risk factors.

CRITICAL ISSUES

The most relevant facts underlying the role of miRNAs in the response to these environmental stressors, including redox regulatory changes and oxidative stress, are highlighted and discussed. In the cases wherein miRNA mutations are relevant for this response, the pertinent literature is also reviewed.

FUTURE DIRECTIONS

We conclude that, even though in some cases important advances have been made regarding close correlations between specific miRNAs and biological responses to environmental risk factors, a need for prospective large-cohort studies is likely necessary to establish causative roles. Antioxid. Redox Signal. 28, 773-796.

Macrophage Migration Inhibitory Factor and microRNA-451a in Response to Mindfulness-based Therapy or Treatment as Usual in Patients with Depression, Anxiety, or Stress and Adjustment Disorders

BACKGROUND

Macrophage migration inhibitory factor is a proinflammatory cytokine that has been associated with various psychiatric disorders. MicroRNA-451a can directly target macrophage migration inhibitory factor and downregulate its expression in cells. However, the role of macrophage migration inhibitory factor and microRNA-451a in psychiatric patients treated with psychotherapeutic interventions is unknown. In this study, our aim was to investigate levels of macrophage migration inhibitory factor and its regulating microRNA-451a in patients with depression, anxiety, or stress and adjustment disorders who underwent mindfulness-based therapy or treatment as usual.

METHODS

A total of 168 patients with psychiatric disorders were included from a randomized controlled trial that compared mindfulness-based therapy with treatment as usual. Plasma levels of macrophage migration inhibitory factor and microRNA-451a were measured at baseline and after the 8-week follow-up using Luminex assay and qPCR.

RESULTS

Macrophage migration inhibitory factor levels decreased significantly in patients posttreatment, whereas microRNA-451a levels showed a nonsignificant change. Macrophage migration inhibitory factor levels were inversely associated with microRNA-451a expression levels at baseline (β=-0.04, P=.008). The change in macrophage migration inhibitory factor levels (follow-up levels minus baseline levels) was associated with the change in microRNA-451a (follow-up levels minus baseline levels) (β=-0.06, P < .0001). The change in either macrophage migration inhibitory factor or microRNA-451a was not associated with improvement in psychiatric symptoms.

CONCLUSION

We demonstrate that the levels of macrophage migration inhibitory factor decreased after psychotherapeutic interventions in patients with psychiatric disorders. However, this reduction was not associated with an improvement in psychiatric symptoms in response to the treatment. We also found an association between macrophage migration inhibitory factor and its regulating microRNA. However, this association needs to be further examined in future studies.

Major depression and its treatment: microRNAs as peripheral biomarkers of diagnosis and treatment response

PURPOSE OF REVIEW

Major depressive disorder (MDD) is among the most prevalent and disabling medical conditions worldwide. Despite its considerable burden, our understanding of its pathophysiology remains rudimentary, and a validated biomarker has yet to be identified. Antidepressants are the most common treatment for MDD, yet roughly one-third of patients experience an inadequate response. Thus, there is a great need for not only identifying biomarkers of MDD but also those that can predict and monitor or just monitor response to treatment.

RECENT FINDINGS

MicroRNAs (miRNAs) act as endogenous fine-tuners and on-off switches of gene expression. Several lines of evidence now suggest that miRNAs are involved in the pathogenesis of neuropsychiatric disorders. As such, miRNAs offer great hope as biomarkers of disease and response to treatment.

SUMMARY

In this review, we discuss the growing field, investigating peripheral miRNAs as potential biomarkers of major depression and treatment response. A noninvasive and validated biomarker of MDD or treatment response will help clinicians guide treatment selection. Ultimately, these findings provide important steps in the development of early diagnostic tools, preventive strategies, and effective pharmacological treatment for psychiatric disorders.

Peripheral blood microRNA and VEGFA mRNA changes following electroconvulsive therapy: implications for psychotic depression

OBJECTIVE

MicroRNAs are short, non-coding molecules that regulate gene expression. Here, we investigate the role of microRNAs in depression and electroconvulsive therapy (ECT).

METHODS

We performed three studies: a deep sequencing discovery-phase study of miRNA changes in whole blood following ECT (n = 16), followed by a validation study in a separate cohort of patients pre-/post-ECT (n = 37) and matched healthy controls (n = 34). Changes in an experimentally validated gene target (VEGFA) were then analysed in patients pre-/post-ECT (n = 97) and in matched healthy controls (n = 53).

RESULTS

In the discovery-phase study, we found no statistically significant differences in miRNA expression from baseline to end of treatment in the group as a whole, but post hoc analysis indicated a difference in patients with psychotic depression (n = 3). In a follow-up validation study, patients with psychotic depression (n = 7) had elevated baseline levels of miR-126-3p (t = 3.015, P = 0.006) and miR-106a-5p (t = 2.598, P = 0.025) compared to healthy controls. Following ECT, these differences disappeared. Baseline VEGFA levels were significantly higher in depressed patients compared to healthy controls (F(1,144) = 27.688, P = <0.001). Following ECT, there was a significant change in VEGFA levels in the psychotic group only (t = 2.915, P = 0.010).

CONCLUSION

Molecular differences (miRNA and VEGFA) may exist between psychotic and non-psychotic depression treated with ECT.

Peripheral Signatures of Psychiatric Disorders: MicroRNAs

MicroRNAs (miRNAs) are 22 nucleotide long RNA transcripts, their synthesis starts in nucleus and continues in cytoplasm. As being critical for post-transcriptional regulators of gene expression they have been investigated in psychiatric disorders. There are numerous studies performed in peripheral tissues for psychiatric disorders. Here in this article, we aimed to review some common miRNAs denoted significant in at least two studies and their relevance to psychiatric research. We focused on miR-320, miR-106, miR-34, miR-223, miR-107, and miR-134.

Potential Use of MicroRNA for Monitoring Therapeutic Response to Antidepressants

Major depressive disorder (MDD) is a serious and common psychiatric disorder that affects millions of people worldwide. The most common treatment methods for MDD are antidepressant drugs, many of which act by regulating monoamines by inhibiting pre-synaptic reuptake and/or by modulating monoamine receptors. Despite advances in antidepressants and other treatment options, therapy is often based on subjective decisions made by the physician. Moreover, it requires time to determine treatment outcome and to define whether the prescribed treatment is effective. Biomarkers may help identify individuals with MDD who are more likely to respond to specific antidepressant treatment and may thus provide more objectivity in treatment decision making. MicroRNA as biomarkers of antidepressant response has engendered substantial enthusiasm. In this review, we give a detailed overview of biomarkers, particularly the major studies that have investigated microRNA in relationship to antidepressant treatment response.

Diagnostic and therapeutic potential of microRNAs in neuropsychiatric disorders: Past, present, and future

Neuropsychiatric disorders are common health problems affecting approximately 1% of the population. Twin, adoption, and family studies have displayed a strong genetic component for many of these disorders; however, the underlying pathophysiological mechanisms and neural substrates remain largely unknown. Given the critical need for new diagnostic markers and disease-modifying treatments, expanding the focus of genomic studies of neuropsychiatric disorders to include the role of non-coding RNAs (ncRNAs) is of growing interest. Of known types of ncRNAs, microRNAs (miRNAs) are 20-25-nucleotide, single-stranded, molecules that regulate gene expression through post-transcriptional mechanisms and have the potential to coordinately regulate complex regulatory networks. In this review, we summarize the current knowledge on miRNA alteration/dysregulation in neuropsychiatric disorders, with a special emphasis on schizophrenia (SCZ), bipolar disorder (BD), and major depressive disorder (MDD). With an eye toward the future, we also discuss the diagnostic and prognostic potential of miRNAs for neuropsychiatric disorders in the context of personalized treatments and network medicine.

Integrative Analysis of Sex-Specific microRNA Networks Following Stress in Mouse Nucleus Accumbens

Adult women are twice as likely as men to suffer from affective and anxiety disorders, although the mechanisms underlying heightened female stress susceptibility are incompletely understood. Recent findings in mouse Nucleus Accumbens (NAc) suggest a role for DNA methylation-driven sex differences in genome-wide transcriptional profiles. However, the role of another epigenetic process-microRNA (miR) regulation-has yet to be explored. We exposed male and female mice to Subchronic Variable Stress (SCVS), a stress paradigm that produces depression-like behavior in female, but not male, mice, and performed next generation mRNA and miR sequencing on NAc tissue. We applied a combination of differential expression, miR-mRNA network and functional enrichment analyses to characterize the transcriptional and post-transcriptional landscape of sex differences in NAc stress response. We find that male and female mice exhibit largely non-overlapping miR and mRNA profiles following SCVS. The two sexes also show enrichment of different molecular pathways and functions. Collectively, our results suggest that males and females mount fundamentally different transcriptional and post-transcriptional responses to SCVS and engage sex-specific molecular processes following stress. These findings have implications for the pathophysiology and treatment of stress-related disorders in women.

Evaluation of Paraoxonase, Arylesterase and Malondialdehyde Levels in Schizophrenia Patients Taking Typical, Atypical and Combined Antipsychotic Treatment

Objective

Human serum paraoxonase (PON1) prevents lipids from peroxidation and functions as an antioxidant mechanism. Malonyldialdehyde (MDA) is the final product of lipid peroxidation and can be used as an indicator of oxidative stress. The aim of this study was to investigate PON1, MDA, and arylesterase (ARY) levels in schizophrenic patients who are taking typical, atypical, or combined (typical and atypical) antipsychotic drug treatment, with respect to those of healthy controls.

Methods

We evaluated 41 patients (11 taking typical antipsychotics, 19 taking atypical antipsychotics, 11 taking combined anti-psychotics) and 43 healthy controls.

Results

MDA levels were higher in schizophrenic patients taking typical antipsychotics compared with healthy controls (p=0.001). ARY levels were higher in patients taking atypical antipsychotics compared with healthy controls (p=0.005). PON1 activity was similar in all groups.

Conclusion

Our results indicate that treatment with typical antipsychotic drugs could be related to increased MDA levels; and antipsychotic medication may increase PON1 levels in schizophrenic patients.

Differential expression of microRNAs in the brains of mice subjected to increasing grade of mild traumatic brain injury

OBJECTIVE

To investigate the effect of heterogeneity in mTBI on miRNA expression in mouse brain and to identify molecular pathways targeted by the modulated miRNAs.

METHODS

A weight drop device was used to induce four increasing grades of mTBI. MiRNA expression was evaluated using TaqMan rodent miRNA arrays. Bioinformatics analysis was done using the DIANA miRPath tool and Ingenuity Pathway Analysis software. Histology of brain sections was evaluated using H&E staining.

RESULTS

No histologic lesions were observed in the brains of injured mice; however, significant modulation in miRNA expression profile was observed. Global miRNA profiling indicated a trend of decrease in the number of modulated miRNAs from 24 hours to day 7 post-injury, except for the most severe grade of mTBI. Canonical pathways like calcium signalling, synaptic pathways and axon guidance pathway were the major targets of the modulated miRNAs. Network correlation analyses indicated an interaction between the modulated miRNAs and putative protein biomarkers of TBI.

CONCLUSIONS

The data demonstrated that varying intensities of mTBI induced a differential miRNA expression profile in the brain post-injury. Pathways such as calcium and synaptic signalling were major targets of modulated miRNAs and may play a role in the pathophysiology of mTBI.

Newer insights into the role of miRNA a tiny genetic tool in psychiatric disorders: focus on post-traumatic stress disorder

Post-traumatic stress disorder (PTSD) is a mental disorder occurring in about 2-9% of individuals after their exposure to life-threatening events, such as severe accidents, sexual abuse, combat or a natural catastrophe. Because PTSD patients are exposed to trauma, it is likely that epigenetic modifications have an important role in disease development and prognosis. For the past two decades, abnormal expression of the epigenetic regulators microRNAs (miRs) and miR-mediated gene regulation have been given importance in a variety of human diseases, such as cancer, heart disease and viral infection. Emerging evidence supports a role for miR dysregulation in psychiatric and neurological disorders, including schizophrenia, bipolar disorder, anxiety, major depressive disorder, autism spectrum disorder and Tourette's syndrome. Recently mounting of evidence supports the role of miR both in preclinical and clinical settings of psychiatric disorders. Abnormalities in miR expression can fine-tune the expression of multiple genes within a biological network, suggesting that miR dysregulation may underlie many of the molecular changes observed in PTSD pathogenesis. This provides strong evidence that miR not only has a critical role in PTSD pathogenesis, but can also open up new avenues for the development of diagnostic tools and therapeutic targets for the PTSD phenotype. In this review, we revisit some of the recent evidence associated with miR and PTSD in preclinical and clinical settings. We also discuss the possible clinical applications and future use of miRs in PTSD therapy.

Serum levels of G protein-coupled estrogen receptor 1 (GPER1) in drug-naive patients with generalized anxiety disorder

Sex hormones, particularly estrogen, are suggested to play a role in the physiopathology of generalized anxiety disorder (GAD). Estrogen functions through the estrogen receptors alpha and beta and the recently discovered G protein-coupled estrogen receptor 1 (GPER1). This study aimed, for the first time, to evaluate serum GPER1 levels in drug-naive patients with GAD. This study included 40 newly diagnosed drug-naive patients with GAD aged between 18 and 50 years and 40 age- and gender-matched healthy controls. Medical histories were obtained, and physical examinations and laboratory tests were conducted; the Hamilton Anxiety Rating Scale (HAM-A) was also used for all participants. Serum GPER1 levels were measured. The serum GPER1 level was significantly higher in the patients with GAD than in the controls. A positive significant correlation was observed between the GPER1 level and the HAM-A score. The receiver operating characteristic analysis revealed a sensitivity, specificity, positive predictive value, and negative predictive value of 85.0%, 82.5%, 82.9%, and 84.6%, respectively, for the presence of anxiety when the serum GPER1 value was ≥0.14 (the area under the curve was 0.904.). In conclusion, this study demonstrated that GPER1 levels were associated with the anxiety levels of patients, and that the serum GPER1 level was a valuable predictor of the presence of anxiety independent of gender.

Reciprocal MicroRNA Expression in Mesocortical Circuit and Its Interplay with Serotonin Transporter Define Resilient Rats in the Chronic Mild Stress

Prolonged stress perturbs physiological balance of a subject and thus can lead to depression. Nevertheless, some individuals are more resilient to stress than the others. Defining molecular factors underlying resilience to stress may contribute to the development of a new antidepressant strategy based on the restoration of resilient phenotype in depressed subjects. We used chronic mild stress (CMS) paradigm—well-characterized animal model of depression which caused in rats behavioral deficits (anhedonia) manifested by decreased consumption of sucrose solution. CMS also generated a proportion of resilient rats which did not alter sucrose consumption despite being stressed. Recently, regulation of a gene expression associated with microRNA (miRNA) is considered as an important factor modulating biochemical response to stress. Based on our previous work and literature survey, we investigated changes in the expression level of seven miRNAs (i.e., miR-18a-5p, miR-34a-5p, miR-135a-5p, miR-195-5p, miR-320-3p, miR-674-3p, miR-872-5p) in mesocortical circuit—crucially involved in stress response in order to find differences between susceptible and resilient phenotype. Bioinformatic analysis showed that all miRNAs of interest potentially target serotonin transporter (SERT). Chronic stress caused global increase in the expression of the abovementioned miRNAs in ventral tegmental area (VTA) of stressed rats followed by parallel decrease in miRNA expression in prefrontal cortex (PCx). This effect was more profound in resilient than anhedonic animals. Moreover, we observed decreased level of SERT in VTA of resilient rats. Our findings show that mesocortical circuit is involved in the response to stress and this phenomenon is more efficient in resilient animals.

Investigation of Dysregulation of Several MicroRNAs in Peripheral Blood of Schizophrenia Patients

Objective

The prevalence of schizophrenia is 1%, and it is a debilitating disorder that often results in a shortened lifespan. Peripheral blood samples are good candidates to investigate because they can be easily drawn, and they are widely studied in psychiatric disorders. MicroRNAs are small non-coding RNA transcripts. They regulate the expression of genes by binding to the 3′-untranslated region (UTR) of mRNAs and pointing them to degrade. In this study, we aimed to investigate the expression of miR-9-5p, miR-29a-3p, miR-106-5p, miR-106b-5p, miR-107, miR-125a-3p, and miR-125b-3p in schizophrenia patients and healthy controls.

Methods

We collected blood samples from 16 patients with schizophrenia and 16 healthy controls. MicroRNAs were measured with reverse transcriptase polymerase chain reaction.

Results

Schizophrenia patients showed statistically significant upregulation of five microRNAs: miR9-5p (p=0.002), miR29a-3p (p<0.001), miR106b-5p (p=0.002), miR125a-3p (p<0.001), and miR125b-3p (p=0.018).

Conclusion

Our results increased the value of the miR106 and miR29 families as potentially and consistently dysregulated in psychiatric disorders. Our results should be considered preliminary, and they need confirmation in future studies with larger sample sizes.

MicroRNAs as biomarkers for major depression: a role for let-7b and let-7c

There is a growing emphasis in the field of psychiatry on the need to identify candidate biomarkers to aid in diagnosis and clinical management of depression, particularly with respect to predicting response to specific therapeutic strategies. MicroRNAs are small nucleotide sequences with the ability to regulate gene expression at the transcriptomic level and emerging evidence from a range of studies has highlighted their biomarker potential. Here we compared healthy controls (n=20) with patients diagnosed with major depression (n=40) and who were treatment-resistant to identify peripheral microRNA biomarkers, which could be used for diagnosis and to predict response to electroconvulsive therapy (ECT) and ketamine (KET) infusions, treatments that have previously shown to be effective in treatment-resistant depression (TRD). At baseline and after treatment, blood samples were taken and symptom severity scores rated using the Hamilton Depression Rating Scale (HDRS). Samples were analyzed for microRNA expression using microarray and validated using quantitative PCR. As expected, both treatments reduced HDRS scores. Compared with controls, the baseline expression of the microRNA let-7b was less by ~40% in TRD patients compared with controls. The baseline expression of let-7c was also lower by ~50% in TRD patients who received ECT. Bioinformatic analysis revealed that let-7b and let-7c regulates the expression of 27 genes in the PI3k-Akt-mTOR signaling pathway, which has previously been reported to be dysfunctional in depression. The expression of miR-16, miR-182, miR-451 and miR-223 were similar to that in controls. Baseline microRNA expression could not predict treatment response and microRNAs were unaffected by treatment. Taken together, we have identified let-7b and let-7c as candidate biomarkers of major depression.

Peripheral whole blood microRNA alterations in major depression and bipolar disorder

Major depression (MD) and bipolar disorder (BD) are severe and potentially life-threating mood disorders whose etiology is to date not completely understood. MicroRNAs (miRNAs) are small non-coding RNAs that regulate protein synthesis post-transcriptionally by base-pairing to target gene mRNAs. Growing evidence indicated that miRNAs might play a key role in the pathogenesis of neuropsychiatric disorders and in the action of psychotropic drugs. On these bases, in this study we evaluated the expression levels of 1733 mature miRNAs annotated in miRBase v.17, through a microarray technique, in the blood of 20 MD and 20 BD patients and 20 healthy controls, in order to identify putative miRNA signatures associated with mood disorders. We found that 5 miRNAs (hsa-let-7a-5p, hsa-let-7d-5p, hsa-let-7f-5p, hsa-miR-24-3p and hsa-miR-425-3p) were specifically altered in MD patients and 5 (hsa-miR-140-3p, hsa-miR-30d-5p, hsa-miR-330-5p, hsa-miR-378a-5p and hsa-miR-21-3p) in BD patients, whereas 2 miRNAs (hsa-miR-330-3p and hsa-miR-345-5p) were dysregulated in both the diseases. The bioinformatic prediction of the genes targeted by the altered miRNAs revealed the possible involvement of neural pathways relevant for psychiatric disorders. In conclusion, the observed results indicate a dysregulation of miRNA blood expression in mood disorders and could indicate new avenues for a better understanding of their pathogenetic mechanisms. The identified alterations may represent potential peripheral biomarkers to be complemented with other clinical and biological features for the improvement of diagnostic accuracy.

Expression of p21-activated kinases 1 and 3 is altered in the brain of subjects with depression

The p21-activated kinases (PAKs) of group I are the main effectors for the small Rho GTPases, critically involved in neurodevelopment, plasticity and maturation of the nervous system. Moreover, the neuronal complexity controlled by PAK1/PAK3 signaling determines the postnatal brain size and synaptic properties. Stress induces alterations at the level of structural and functional synaptic plasticity accompanied by reductions in size and activity of the hippocampus and the prefrontal cortex (PFC). These abnormalities are likely to contribute to the pathology of depression and, in part, reflect impaired cytoskeleton remodeling pointing to the role of Rho GTPase signaling. Thus, the present study assessed the expression of the group I PAKs and their activators in the brain of depressed subjects. Using quantitative polymerase chain reaction (qPCR), mRNA levels and coexpression of the group I PAKs: PAK1, PAK2, and PAK3 as well as of their activators: RAC1, CDC42 and ARHGEF7 were examined in postmortem samples from the PFC (n=25) and the hippocampus (n=23) of subjects with depression and compared to control subjects (PFC n=24; hippocampus n=21). Results demonstrated that mRNA levels of PAK1 and PAK3, are significantly reduced in the brain of depressed subjects, with PAK1 being reduced in the PFC and PAK3 in the hippocampus. No differences were observed for the ubiquitously expressed PAK2. Following analysis of gene coexpression demonstrated disruption of coordinated gene expression in the brain of subjects with depression. Abnormalities in mRNA expression of PAK1 and PAK3 as well as their altered coexpression patterns were detected in the brain of subjects with depression.

MicroRNA-511 Binds to FKBP5 mRNA, Which Encodes a Chaperone Protein, and Regulates Neuronal Differentiation

Single nucleotide polymorphisms in the FKBP5 gene increase the expression of the FKBP51 protein and have been associated with increased risk for neuropsychiatric disorders such as major depression and post-traumatic stress disorder. Moreover, levels of FKBP51 are increased with aging and in Alzheimer disease, potentially contributing to disease pathogenesis. However, aside from its glucocorticoid responsiveness, little is known about what regulates FKBP5 In recent years, non-coding RNAs, and in particular microRNAs, have been shown to modulate disease-related genes and processes. The current study sought to investigate which miRNAs could target and functionally regulate FKBP5 Following in silico data mining and initial target expression validation, miR-511 was found to suppress FKBP5 mRNA and protein levels. Using luciferase p-miR-Report constructs and RNA pulldown assays, we confirmed that miR-511 bound directly to the 3'-UTR of FKBP5, validating the predicted gene-microRNA interaction. miR-511 suppressed glucocorticoid-induced up-regulation of FKBP51 in cells and primary neurons, demonstrating functional, disease-relevant control of the protein. Consistent with a regulator of FKBP5, miR-511 expression in the mouse brain decreased with age but increased following chronic glucocorticoid treatment. Analysis of the predicted target genes of miR-511 revealed that neurogenesis, neuronal development, and neuronal differentiation were likely controlled by these genes. Accordingly, miR-511 increased neuronal differentiation in cells and enhanced neuronal development in primary neurons. Collectively, these findings show that miR-511 is a functional regulator of FKBP5 and can contribute to neuronal differentiation.

Evaluation of malondialdehyde, superoxide dismutase and catalase activity and their diagnostic value in drug naïve, first episode, non-smoker major depression patients and healthy controls

Major depression is a most frequent disorder, its diagnosis depends on patient interview, and yet we do not have a reliable biomarker for depression. Oxidative stress is defined as increase in oxidation or decrease is antioxidant defense mechanisms. Here, we aimed to investigate malondialdehyde (MDA), superoxide dismutase (SOD) and catalase (CAT) activity and their diagnostic performance in depressed patients and healthy controls. We collected blood samples from 50 patients and 50 controls. We found MDA levels were significantly higher in the patients than controls, with medians at 4.04nmol/mg and 1.64nmol/mg, respectively, p<0.001. SOD activity was significantly decreased in depressed patients than healthy controls, with means at 143.50U/mg and 298.12U/mg, respectively, p<0.001. CAT activity was similar in both groups, p=0.517. ROC analysis showed good diagnostic value for MDA and SOD, with the area under the curve at 1.0 for both. We found high correlation between SOD and Ham-D scores (r=0.747, p<0.0001) and between MDA and Ham-D scores (r=0.785, p<0.0001). Overall, these results demonstrate that oxidative stress is increased in depressed patients. MDA increase seem to be a common finding for major depression. We believe MDA could be a good biomarker candidate for major depression, but not SOD. Future studies should focus on the diagnostic value of MDA in larger samples.

Preliminary comparison of plasma notch-associated microRNA-34b and -34c levels in drug naive, first episode depressed patients and healthy controls

BACKGROUND

Major depressive disorder (MDD) is a common debilitating disease of unknown etiology. The expression of miRNA is closely related to depression and efficacy of antidepressant therapy. However, whether Notch-associated miRNAs expressions involved in first-episode of MDD are still unknown.

METHODS

In this study, the expression levels of Notch1, Hes1 mRNA and 5 miRNAs (miR-369-3p, miR-34b-5p, miR-34c-5p, miR-381 and miR-107) in peripheral blood leukocytes of 32 MDD patients and 32 healthy controls were detected using qRT-PCR method. We also assessed the severity of depressive symptom, suicide risk level, negative life events and event-related potential P300.

RESULTS

The expression levels of miR-34b-5p (62.49 as the median of cases group and 38.62 as median of control group) and miR-34c-5p (7.17 as the median of cases group and 5.45 as median of control group) in MDD patients were significantly higher than these in control subjects. NOTCH1 gene were significantly lower in MDD patients (5.35 as the median of cases group and 6.80 as median of control group), and was negatively correlated with the expression miR-34c-5p and miR-34b-5p. The expression level of miR-34b-5p and miR-369-3p were significantly lower in patients with suicide idea. N1 latency of P300 were positive correlated with miR-34c-5p, miR-107 and miR-381, and P2 latency of P300 were positive correlated with miR-34c-5p, miR-107 and miR-381.

LIMITATIONS

The sample size was small and the role of candidate miRNAs in the regulation of Notch1 gene and cognitive function are still need to be further investigated.

CONCLUSIONS

Differentially Notch-associated miRNAs expressions in peripheral blood might be involved in MDD, and the miR-34b-5p and miR-34c-5p levels in peripheral blood leukocytes are closely related to MDD, suicide idea and cognitive function, further studies with large sample size are warranted to test the feasibility of these miRNAs serving as biomarkers for MDD.