Higher serum tropomyosin-related kinase B protein level in major depression

Identification of key genes in the pathogenesis of preeclampsia via bioinformatic analysis and experimental verification

Background

Preeclampsia (PE) is the primary cause of perinatal maternal-fetal mortality and morbidity. The exact molecular mechanisms of PE pathogenesis are largely unknown. This study aims to identify the hub genes in PE and explore their potential molecular regulatory network.

Methods

We downloaded the GSE148241, GSE190971, GSE74341, and GSE114691 datasets for the placenta and performed a differential expression analysis to identify hub genes. We performed Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), Disease Ontology (DO), Gene Set Enrichment Analysis (GSEA), and Protein-Protein Interaction (PPI) Analysis to determine functional roles and regulatory networks of differentially expressed genes (DEGs). We then verified the DEGs at transcriptional and translational levels by analyzing the GSE44711 and GSE177049 datasets and our clinical samples, respectively.

Results

We identified 60 DEGs in the discovery phase, consisting of 7 downregulated genes and 53 upregulated genes. We then identified seven hub genes using Cytoscape software. In the verification phase, 4 and 3 of the seven genes exhibited the same variation patterns at the transcriptional level in the GSE44711 and GSE177049 datasets, respectively. Validation of our clinical samples showed that CADM3 has the best discriminative performance for predicting PE.

Conclusion

These findings may enhance the understanding of PE and provide new insight into identifying potential therapeutic targets for PE.

Effects of neuronavigation-guided rTMS on serum BDNF, TrkB and VGF levels in depressive patients with suicidal ideation

BACKGROUND

Neuronavigation-guided high-dose repetitive transcranial magnetic stimulation (rTMS) could rapidly treat depressive patients with suicidal ideation. But the mechanism of rTMS still needs to be elucidated. This study aims to investigate if rTMS improves suicidal ideation and depressive symptoms by influencing brain-derived neurotrophic factor (BDNF), tropomysin receptor kinase B (TrkB) and VGF levels.

METHODS

In the present 1-week study, 59 treatment-naive depressive patients with suicidal ideation were randomly assigned to the active (n = 31) or sham (n = 28) rTMS group. The severity of suicidal ideation and depression were measured by the Beck Scale for Suicide Ideation, the Hamilton Depression Rating Scale and Montgomery-Asberg Depression Rating Scale. Fasting venous blood samples were collected at baseline and after treatment. Serum protein concentrations of BDNF, TrkB and VGF were measured by enzyme linked immunosorbent assay.

RESULTS

We found after treatment the levels of BDNF in the active rTMS group were higher than the sham group (p = 0.011), TrkB levels were decreased in the active group (p < 0.001), VGF levels were increased in the active group (p = 0.005). Post-treatment VGF levels in the active group were higher than the sham group (p = 0.008). However, there were no significant correlation between changes in BDNF, TrkB and VGF levels and the changes in clinical variables.

LIMITATIONS

Participants taking medication may affect the results.

CONCLUSIONS

Our results suggest that the BDNF-TrkB pathway and VGF may be implicated in the mechanisms underlying neuronavigation-guided rTMS for treating depressive patients with suicidal ideation.

Association of peripheral manifestation of brain-derived neurotrophic factor with depression: A meta-analysis

BACKGROUND

The relationship between brain-derived neurotrophic factor (BDNF) and depression is a hot topic in research as several results of preclinical and clinical studies have shown controversial results. Our meta-analysis aims to evaluate and update the current status of peripheral BDNF with depression.

METHODS

We performed a meta-analysis by comprehensively searching PubMed and Web of Science for English-language literature from inception to 1st of June 2020. The search terms included brain-derived neurotrophic factor or BDNF in combination with depression, without year restriction. Using STATA software, data were pooled using a random-effects model.

RESULTS

In our literature search, 24 studies involving 1130 depressed patients and 1378 healthy individuals met our inclusion criteria. The results of our meta-analysis showed that the peripheral levels of BDNF levels significantly decreased in depression than nondepressed healthy controls (SMD = -0.89, 95% CI = -1.41, -0.38, p < .0001); however, the significant heterogeneity among studies (Q = 740.91, I²  = 96.8; p < .001) was discovered. Trim-and-fill estimations for the adjustment of publication bias indicated that publication bias had no impact on our results. Our sub-group analysis showed that a history of depression and alcohol consumption had an effect on the level of BDNF. In addition, age and gender did not affect the heterogeneity of BDNF in the meta-analysis.

CONCLUSIONS

Although decreased peripheral expression of BDNF certainly presents a risk of depression, we cannot find a definite relationship between the peripheral level of BDNF with depression to use BDNF as a reliable biomarker to assess the depression in clinical practice. We propose that future research should consider all the factors affecting BDNF and assess the level of proBDNF and mBDNF separately while evaluating the patients with depression objectively.

Brain-derived neurotrophic factor and mental disorders

Brain-derived neurotrophic factor (BDNF) is a neurotrophin that modulates neuroplasticity in the brain, and is one of the most widely investigated molecule in psychiatric disorders. The researches of BDNF emcompassed the advance of investigative techniques of past decades. BDNF researches ranged from protein quantilization, to RNA expression measurements, to DNA sequencing, and lately but not lastly, epigenetic studies. In this review, we will briefly address findings on BDNF protein levels, mRNA expression, Val66Met polymorphism, and epigenetic modifications, in schizophrenia, major depressive disorder (MDD), and bipolar disorder.

Role of tissue-type plasminogen activator and plasminogen activator inhibitor-1 in psychological stress and depression

Major depressive disorder is a common illness worldwide, but the pathogenesis of the disorder remains incompletely understood. The tissue-type plasminogen activator-plasminogen proteolytic cascade is highly expressed in the brain regions involved in mood regulation and neuroplasticity. Accumulating evidence from animal and human studies suggests that tissue-type plasminogen activator and its chief inhibitor, plasminogen activator inhibitor-1, are related to stress reaction and depression. Furthermore, the neurotrophic hypothesis of depression postulates that compromised neurotrophin brain-derived neurotrophic factor (BDNF) function is directly involved in the pathophysiology of depression. In the brain, the proteolytic cleavage of proBDNF, a BDNF precursor, to mature BDNF through plasmin represents one mechanism that can change the direction of BDNF action. We also discuss the implications of tissue-type plasminogen activator and plasminogen activator inhibitor-1 alterations as biomarkers for major depressive disorder. Using drugs that increase tissue-type plasminogen activator or decrease plasminogen activator inhibitor-1 levels may open new avenues to develop conceptually novel therapeutic strategies for depression treatment.

Combined serum levels of multiple proteins in tPA-BDNF pathway may aid the diagnosis of five mental disorders

Mental disorders are severe, disabling conditions with unknown etiology and are commonly misdiagnosed when clinical symptomology criteria are solely used. Our previous work indicated that combination of serum levels of multiple proteins in tissue plasminogen activator (tPA)-brain-derived neurotrophic factor (BDNF) pathway improved accuracy of diagnosis of major depressive disorder (MDD). Here, we measured serum levels of tPA, plasminogen activator inhibitor-1 (PAI-1), BDNF, precursor-BDNF (proBDNF), tropomyosin-related kinase B (TrkB) and neurotrophin receptor p75 (p75NTR) in patients with paranoid schizophrenia (SZ, n = 34), MDD (n = 30), bipolar mania (BM, n = 30), bipolar depression (BD, n = 22), panic disorder (PD, n = 30), and healthy controls (HCs, n = 30) by Enzyme-linked immunosorbent assay kits. We used receiver operating characteristic (ROC) curve to analyze diagnostic potential of these proteins. We found, compared with HCs, that serum tPA and proBDNF were lower in SZ, BM and BD; TrkB was lower in SZ and BD; and p75NTR was declined in SZ and BM. ROC analysis showed that combined serum level of tPA, PAI-1, BDNF, proBDNF, TrkB and p75NTR was better than any single protein in accuracy of diagnosis and differentiation, suggesting that the combination of multiple serum proteins levels in tPA-BDNF pathway may have a potential for a diagnostic panel in mental disorders.

The serum protein levels of the tPA-BDNF pathway are implicated in depression and antidepressant treatment

Evidence demonstrates that brain-derived neurotrophic factor (BDNF) has a pivotal role in the pathogenesis of major depressive disorder (MDD). Precursor-BDNF (proBDNF) and mature BDNF (mBDNF) have opposing biological effects in neuroplasticity, and the tissue-type plasminogen activator (tPA)/plasmin system is crucial in the cleavage processing of proBDNF to mBDNF. However, very little is known about the role of the tPA-BDNF pathway in MDD. We examined serum protein concentrations in the tPA-BDNF pathway, including tPA, BDNF, tropomyosin receptor kinase B (TrkB), proBDNF and p75NTR, obtained from 35 drug-free depressed patients before and after 8 weeks of escitalopram (mean 12.5 mg per day) or duloxetine (mean 64 mg per day) treatment and 35 healthy controls using sandwich ELISA (enzyme-linked immunosorbent assay) methods. Serum tPA and BDNF and the ratio of BDNF/proBDNF were significantly lower in the MDD patients than in controls, whereas TrkB, proBDNF and its receptor p75NTR were higher. After 8 weeks of treatment, tPA, BDNF and proBDNF and the BDNF/proBDNF ratio were reversed, but p75NTR was higher than baseline, and TrkB was not significantly changed. tPA, BDNF, TrkB, proBDNF and p75NTR all yielded fairly good or excellent diagnostic performance (area under the receiver operating characteristic curve (AUC) >0.8 or 0.9). Combination of these five proteins demonstrated much better diagnostic effectiveness (AUC: 0.977) and adequate sensitivity and specificity of 88.1% and 92.7%, respectively. Our results suggest that the tPA-BDNF lysis pathway may be implicated in the pathogenesis of MDD and the mechanisms underlying antidepressant therapeutic action. The combination of tPA, BDNF, TrkB, proBDNF and p75NTR may provide a diagnostic biomarker panel for MDD.

Combining ECT with pharmacological treatment of depressed inpatients in a naturalistic study is not associated with serum BDNF level increase

BACKGROUND

BDNF blood levels are reduced in MDD. They can be increased with pharmacologic treatment and ECT, but it is not clear whether the combination of treatments promotes an additional increase. The present study aims to evaluate whether combined treatment promotes an increase in BDNF, restoring the level to that of non-depressed controls.

METHODS

Ninety-nine adult inpatients were invited to participate in this naturalistic prospective cohort study between May 2011 and April 2013. Diagnosis was made by MINI, and the symptoms were evaluated at admission and at discharge by HDRS-17. Those inpatients with a diagnosis of depression were included and divided into two groups: those who underwent combined ECT and medication (31 subjects) and those who used only pharmacotherapy (68 subjects). Serum BDNF was measured in blood samples collected at admission and discharge. One hundred healthy blood donors without any psychiatric diagnosis were included as a control group.

RESULTS

There were no significant differences in serum BDNF levels between the combined and pharmacological groups at admission and at discharge, and no significant variation in BDNF occurred in any group during the treatment. There were no interactions between time and treatment groups nor significant time effects or treatment group effects for BDNF in the Generalized Estimating Equation Model (GEE). The control group had significantly higher serum BDNF levels in comparison with each of the treatment groups at admission and discharge (p = 0.00).

CONCLUSION

Combination of ECT with pharmacological treatment did not result in increased serum BDNF levels and did not restore levels to that of controls.

Advances in biomarkers of major depressive disorder

Major depressive disorder (MDD) is characterized by mood, vegetative, cognitive, and even psychotic symptoms and signs that can cause substantial impairments in quality of life and functioning. Biomarkers are measurable indicators that could help diagnosing MDD or predicting treatment response. In this chapter, lipid profiles, immune/inflammation, and neurotrophic factor pathways that have long been implicated in the pathogenesis of MDD are discussed. Then, pharmacogenetics and epigenetics of serotonin transport and its metabolism pathway, brain-derived neurotrophic factor, and abnormality of hypothalamo-pituitary-adrenocortical axis also revealed new biomarkers. Lastly, new techniques, such as proteomics and metabolomics, which allow researchers to approach the studying of MDD with new directions and make new discoveries are addressed. In the future, more data are needed regarding pathophysiology of MDD, including protein levels, single nucleotide polymorphism, epigenetic regulation, and clinical data in order to better identify reliable and consistent biomarkers for diagnosis, treatment choice, and outcome prediction.

TrkB receptor signalling: implications in neurodegenerative, psychiatric and proliferative disorders

The Trk family of receptors play a wide variety of roles in physiological and disease processes in both neuronal and non-neuronal tissues. Amongst these the TrkB receptor in particular has attracted major attention due to its critical role in signalling for brain derived neurotrophic factor (BDNF), neurotrophin-3 (NT3) and neurotrophin-4 (NT4). TrkB signalling is indispensable for the survival, development and synaptic plasticity of several subtypes of neurons in the nervous system. Substantial evidence has emerged over the last decade about the involvement of aberrant TrkB signalling and its compromise in various neuropsychiatric and degenerative conditions. Unusual changes in TrkB signalling pathway have also been observed and implicated in a range of cancers. Variations in TrkB pathway have been observed in obesity and hyperphagia related disorders as well. Both BDNF and TrkB have been shown to play critical roles in the survival of retinal ganglion cells in the retina. The ability to specifically modulate TrkB signalling can be critical in various pathological scenarios associated with this pathway. In this review, we discuss the mechanisms underlying TrkB signalling, disease implications and explore plausible ameliorative or preventive approaches.

Serum protein levels of brain-derived neurotrophic factor and tropomyosin-related kinase B in bipolar disorder: effects of mood stabilizers

AIM

In this study, we investigated serum protein levels of brain-derived neurotrophic factor (BDNF) and its receptor tropomyosin-related kinase B (TrkB) in patients with bipolar disorder.

METHODS

Over a 2-year period, 26 patients with bipolar I disorder (manic episode) and 56 healthy controls were recruited. The Young Mania Rating Scale scores of patients with bipolar mania were >26. Serum BDNF and TrkB protein levels were measured with ELISA kits.

RESULTS

Using ANCOVA with age adjustment, we found that there were no significant differences in serum BDNF protein levels between patients with bipolar mania and healthy controls (p = 0.582). In contrast, the serum TrkB protein level was significantly higher in bipolar mania patients than in healthy controls (p = 0.001), especially in women (p = 0.001). Of 26 patients with bipolar mania, 21 underwent a second measurement of serum BDNF and TrkB protein levels after a 4-week treatment with mood stabilizers. There were no significant changes in serum BDNF or TrkB protein levels.

CONCLUSION

These findings suggest that serum TrkB protein levels may play an important role in the psychopathology of bipolar mania. However, a larger sample size is needed to confirm these results.