Dysregulation of the fibroblast growth factor system in major depression

Identifying behavior regulatory leverage over mental disorders transcriptomic network hubs toward lifestyle-dependent psychiatric drugs repurposing

BACKGROUND

There is a vast prevalence of mental disorders, but patient responses to psychiatric medication fluctuate. As food choices and daily habits play a fundamental role in this fluctuation, integrating machine learning with network medicine can provide valuable insights into disease systems and the regulatory leverage of lifestyle in mental health.

METHODS

This study analyzed coexpression network modules of MDD and PTSD blood transcriptomic profile using modularity optimization method, the first runner-up of Disease Module Identification DREAM challenge. The top disease genes of both MDD and PTSD modules were detected using random forest model. Afterward, the regulatory signature of two predominant habitual phenotypes, diet-induced obesity and smoking, were identified. These transcription/translation regulating factors (TRFs) signals were transduced toward the two disorders' disease genes. A bipartite network of drugs that target the TRFS together with PTSD or MDD hubs was constructed.

RESULTS

The research revealed one MDD hub, the CENPJ, which is known to influence intellectual ability. This observation paves the way for additional investigations into the potential of CENPJ as a novel target for MDD therapeutic agents development. Additionally, most of the predicted PTSD hubs were associated with multiple carcinomas, of which the most notable was SHCBP1. SHCBP1 is a known risk factor for glioma, suggesting the importance of continuous monitoring of patients with PTSD to mitigate potential cancer comorbidities. The signaling network illustrated that two PTSD and three MDD biomarkers were co-regulated by habitual phenotype TRFs. 6-Prenylnaringenin and Aflibercept were identified as potential candidates for targeting the MDD and PTSD hubs: ATP6V0A1 and PIGF. However, habitual phenotype TRFs have no leverage over ATP6V0A1 and PIGF.

CONCLUSION

Combining machine learning and network biology succeeded in revealing biomarkers for two notoriously spreading disorders, MDD and PTSD. This approach offers a non-invasive diagnostic pipeline and identifies potential drug targets that could be repurposed under further investigation. These findings contribute to our understanding of the complex interplay between mental disorders, daily habits, and psychiatric interventions, thereby facilitating more targeted and personalized treatment strategies.

Treatment resistant depression: A case of Muenke syndrome

Major depressive disorder is a complex neuropsychiatric disorder and one of the leading causes of disability in developed countries. Treatment-resistant depression is defined as the failure of at least two adequate treatment trials. The Muenke Syndrome is an autosomal dominant disorder caused by a mutation of the fibroblast growth factor receptor 3 (FGFR3). The fibroblast growth factor (FGF) family has often been implicated in mood disorders in the literature. We present here the case of a patient with a treatment-resistant depression and a concomitant Muenke Syndrome. We propose a relationship between the two pathologies as the expression of the FGF family has been shown to be dysregulated in depressed humans, post-mortem depressed human's brains and rodent's models of depression and anxiety. In particular, FGFR3 and its major ligand, FGF9, had been shown to be down-regulated and up-regulated, respectively, in cortical areas implicated in mood disorders. Since the FGF family plays a key role in neurodevelopment and neuroplasticity, among others things, a genetic mutation in a member of the family, such as FGFR3, could lead to depressive symptoms, as in our reported case. The implication is that the FGF family may be an important target for the treatment of neuropsychiatric disorders. We also conclude that depressive symptoms should be investigated in cases of Muenke Syndrome, as FGF dysregulation in depressed patients.

An Astroglial Basis of Major Depressive Disorder: Molecular, Cellular, and Circuit Features

Major depressive disorder is a common psychiatric disorder and a leading cause of disability worldwide. Astrocytes play a role in the maintenance of the function of the central nervous system, both physiologically and pathologically. Accumulated evidence indicates that the astrocyte is an important contributor to the pathophysiology of major depressive disorder including blood-brain barrier integrity, gap junctions, gliotransmission, glutamate homeostasis, and energy metabolism. Here, we comprehensively summarize an astroglial basis for major depressive disorder based on molecular, cellular, and circuit properties, suggesting that astrocytes appear to be highly sensitive to stress and are likely to be uniquely positioned to integrate peripheral and central stress responses.

Postmortem evidence of decreased brain pH in major depressive disorder: a systematic review and meta-analysis

INTRODUCTION

Major depressive disorder (MDD) is a prevalent and debilitating mental disorder that shares symptoms, genetics, and molecular changes in the brain with other psychiatric disorders, such as schizophrenia and bipolar disorder. Decreased brain pH, associated with increased lactate levels due to altered energy metabolism and neuronal hyperexcitation, has been consistently observed in schizophrenia and bipolar disorder. We recently demonstrated similar brain alterations in various animal models of neuropsychiatric disorders, including MDD. However, our understanding of brain pH alterations in human patients with MDD remains limited.

METHODS

We conducted meta-analyses to assess postmortem brain pH in patients with MDD compared to control subjects, examining its relationships with recurrence of depressive episodes and illness duration, utilizing publicly available demographic data. Studies reporting individual raw pH data were identified through searches in the Stanley Medical Research Institute database, NCBI GEO database, PubMed, and Google Scholar. The data were analyzed using the random effects model, ANOVA, and ANCOVA.

RESULTS

The random effects model, using 39 curated datasets (790 patients and 957 controls), indicated a significant decrease in brain pH in patients with MDD (Hedges' g = -0.23, p = 0.0056). A two-way ANCOVA revealed that the effect of diagnosis on pH remained significant when considering covariates, including postmortem interval, age at death, and sex. Patients with recurrent episodes, but not a single episode, showed significantly lower pH than controls in both females and males (256 patients and 279 controls from seven datasets). Furthermore, a significant negative correlation was observed between brain pH and illness duration (115 patients from five datasets). Female preponderance of decreased pH was also found, possibly due to a longer illness duration and a higher tendency of recurrent episodes in females.

CONCLUSION

This study suggests a decrease in brain pH in patients with MDD, potentially associated with recurrent episodes and longer illness duration. As suggested from previous animal model studies, altered brain energy metabolism, leading to decreased pH, may serve as a potential transdiagnostic endophenotype for MDD and other neuropsychiatric disorders.

Neuritin Controls Axonal Branching in Serotonin Neurons: A Possible Mediator Involved in the Regulation of Depressive and Anxiety Behaviors via FGF Signaling

Abnormal neuronal morphological features, such as dendrite branching, axonal branching, and spine density, are thought to contribute to the symptoms of depression and anxiety. However, the role and molecular mechanisms of aberrant neuronal morphology in the regulation of mood disorders remain poorly characterized. Here, we show that neuritin, an activity-dependent protein, regulates the axonal morphology of serotonin neurons. Male neuritin knock-out (KO) mice harbored impaired axonal branches of serotonin neurons in the medial prefrontal cortex and basolateral region of the amygdala (BLA), and male neuritin KO mice exhibited depressive and anxiety-like behaviors. We also observed that the expression of neuritin was decreased by unpredictable chronic stress in the male mouse brain and that decreased expression of neuritin was associated with reduced axonal branching of serotonin neurons in the brain and with depressive and anxiety behaviors in mice. Furthermore, the stress-mediated impairments in axonal branching and depressive behaviors were reversed by the overexpression of neuritin in the BLA. The ability of neuritin to increase axonal branching in serotonin neurons involves fibroblast growth factor (FGF) signaling, and neuritin contributes to FGF-2-mediated axonal branching regulation in vitro. Finally, the oral administration of an FGF inhibitor reduced the axonal branching of serotonin neurons in the brain and caused depressive and anxiety behaviors in male mice. Our results support the involvement of neuritin in models of stress-induced depression and suggest that neuronal morphological plasticity may play a role in controlling animal behavior.

VEGF, IGF-1 and FGF-2 Serum Levels in Children and Adolescents with Autism Spectrum Disorder with and without Bipolar Disorder

PURPOSE

To investigate serum levels of VEGF, IGF-1 and FGF-2, and relationships with several clinical characteristics in children and adolescents with autism spectrum disorder (ASD) with and without bipolar disorder (BD).

METHOD

40 subjects with ASD + BD as study group, and 40 subjects with ASD as control group were included. Serum levels of VEGF, IGF-1, and FGF-2 were measured using commercial enzyme-linked immunosorbent assay kits.

RESULTS

The study group was significantly higher than the control group in terms of ASD severity, self-harming behavior and sleep disturbance. Serum VEGF and FGF-2 levels were significantly higher in the ASD + BD group than in the control group. There was no significant difference in serum IGF-1 levels between the two groups. There was no correlation between VEGF, IGF-1 and FGF-2 serum levels and ASD severity in the study group. However there was a negative correlation between VEGF levels and age at first diagnosis of BD, and a positive correlation between IGF-1 levels and the number of bipolar episodes in the study group.

CONCLUSION

Growth factors like VEGF and FGF-2 may be potential biomarkers of bipolar disorder in young subjects with ASD. Given the difficulty of clinical management of BD in young subjects with ASD, potential biomarkers would help clinicians in the diagnosis and follow up of BD in this special population. Further research is needed whether VEGF and FGF-2 can be potential biomarkers in the clinical management of young subjects with ASD and BD.

Unraveling the link between heavy metals, perfluoroalkyl substances and depression: Insights from epidemiological and bioinformatics strategies

Heavy metals and per- and polyfluoroalkyl substances (PFASs) have become particularly important when studying the development of depression, a common illness that severely restricts psychosocial functioning and diminishes quality of life. Therefore, the potential joint effects of heavy metal and PFAS exposure on depression, as well as the underlying mechanisms involved, were investigated by using integrated epidemiological and bioinformatic approaches in the present study. A thorough analysis of 7301 samples from the National Health and Nutrition Examination Survey (NHANES) cycles that occurred between 2005 and 2018 was performed. Single-exposure studies have shown that cadmium exposure is positively associated with depression, whereas perfluorooctanesulfonic acid (PFOS) exposure and perfluorodecanoic acid (PFDE) exposure are negatively associated with depression. Furthermore, the Bayesian kernel machine regression (BKMR) and quantile g-computation (QGcomp) models were employed to investigate the collective impact of exposure to mixed metals on depression. Cadmium emerged as the principal contributor to depression. Moreover, the addition of PFAS to the metal mixture had an antagonistic effect on depression, with PFOS having the most prominent influence. Analysis of the effects of co-exposure to cadmium and PFOS confirmed the presence of an antagonistic effect. The inflection points of cadmium and PFOS were determined to be -1.11 and 2.27, respectively. Additionally, exposure to cadmium and PFOS had the opposite effects on two crucial pathways, namely, the rap1 and calcium signaling pathways, which involve core genes related to depression such as ADORA2A, FGF2, and FGFR1. These findings have significant implications for future studies and provide new strategies for exploring the mechanisms underlying co-exposure effects.

Precision Medicine in Depression: The Role of Proteomics and Metabolomics in Personalized Treatment Approaches

Depression, or major depressive disorder (MDD), is a widespread mental health condition marked by enduring feelings of sorrow and loss of interest. Treatment of depression frequently combines psychotherapy, medication, and lifestyle modifications. However, the occurrence of treatment resistance in certain individuals makes it difficult for physicians to effectively manage this disorder, calling for the implementation of alternative therapeutic strategies. Recently, precision medicine has gained increased attention in the field of mental health, paving the way for more personalized and effective therapeutic interventions in depression. Also known as personalized medicine, this approach relies on genetic composition, molecular profiles, and environmental variables to customize therapies to individual patients. In particular, precision medicine has offered novel viewpoints on depression through two specific domains: proteomics and metabolomics. On one hand, proteomics is the thorough study of proteins in a biological system, while metabolomics focuses on analyzing the complete set of metabolites in a living being. In the past few years, progress in research has led to the identification of numerous depression-related biomarkers using proteomics and metabolomics techniques, allowing for early identification, precise diagnosis, and improved clinical outcome. However, despite significant progress in these techniques, further efforts are required for advancing precision medicine in the diagnosis and treatment of depression. The overarching goal of this chapter is to provide the current state of knowledge regarding the use of proteomics and metabolomics in identifying biomarkers related to depression. It also highlights the potential of proteomics and metabolomics in elucidating the intricate processes underlying depression, opening the door for tailored therapies that could eventually enhance clinical outcome in depressed patients. This chapter finally discusses the main challenges in the use of proteomics and metabolomics and discusses potential future research directions.

Fibroblast growth factor 9 (FGF9)-mediated neurodegeneration: Implications for progressive multiple sclerosis?

AIMS

Fibroblast growth factor (FGF) signalling is dysregulated in multiple sclerosis (MS) and other neurological and psychiatric conditions, but there is little or no consensus as to how individual FGF family members contribute to disease pathogenesis. Lesion development in MS is associated with increased expression of FGF1, FGF2 and FGF9, all of which modulate remyelination in a variety of experimental settings. However, FGF9 is also selectively upregulated in major depressive disorder (MDD), prompting us to speculate it may also have a direct effect on neuronal function and survival.

METHODS

Transcriptional profiling of myelinating cultures treated with FGF1, FGF2 or FGF9 was performed, and the effects of FGF9 on cortical neurons investigated using a combination of transcriptional, electrophysiological and immunofluorescence microscopic techniques. The in vivo effects of FGF9 were explored by stereotactic injection of adeno-associated viral (AAV) vectors encoding either FGF9 or EGFP into the rat motor cortex.

RESULTS

Transcriptional profiling of myelinating cultures after FGF9 treatment revealed a distinct neuronal response with a pronounced downregulation of gene networks associated with axonal transport and synaptic function. In cortical neuronal cultures, FGF9 also rapidly downregulated expression of genes associated with synaptic function. This was associated with a complete block in the development of photo-inducible spiking activity, as demonstrated using multi-electrode recordings of channel rhodopsin-transfected rat cortical neurons in vitro and, ultimately, neuronal cell death. Overexpression of FGF9 in vivo resulted in rapid loss of neurons and subsequent development of chronic grey matter lesions with neuroaxonal reduction and ensuing myelin loss.

CONCLUSIONS

These observations identify overexpression of FGF9 as a mechanism by which neuroaxonal pathology could develop independently of immune-mediated demyelination in MS. We suggest targeting neuronal FGF9-dependent pathways may provide a novel strategy to slow if not halt neuroaxonal atrophy and loss in MS, MDD and potentially other neurodegenerative diseases.

A review of new insights into existing major depressive disorder biomarkers

As major depressive disorder (MDD) is such a diverse condition, there are currently no clear ways for determining its severity, endophenotype, or therapy response. The distinctive nature of depression, the variability of analysis in literature and the large number of conceptually complicated biomarkers are some of the many reasons for the lack of progress. Markers are involved in the process of neurotrophic, metabolic, and inflammation as well as neuroendocrine and neurotransmitter systems' components. Some clinical indicators are strong enough so that can be measured using assessments of proteomic, genetic, metabolomics, neuroimaging, epigenetic and transcriptomic. Markers of oxidative stress, endocrine, inflammatory, proteomic, and growth indicators are currently among the promising biologic systems/markers identified in this analysis. This narrative review examines succinct studies which investigated cytokines of inflammatory factors, peripheral factors of development, metabolic and endocrine markers as pathophysiological biomarkers of MDD, and treatment responses. Endocrine and metabolic alterations have also been linked to MDD in various studies. So, this study summarizes all of the numerous biomarkers that are significant in the detection or treatment of MDD patients. The paper also provides an overview of various biomarkers which are important for the regulation and its effects on MDD.

AMEND: active module identification using experimental data and network diffusion

BACKGROUND

Molecular interaction networks have become an important tool in providing context to the results of various omics experiments. For example, by integrating transcriptomic data and protein-protein interaction (PPI) networks, one can better understand how the altered expression of several genes are related with one another. The challenge then becomes how to determine, in the context of the interaction network, the subset(s) of genes that best captures the main mechanisms underlying the experimental conditions. Different algorithms have been developed to address this challenge, each with specific biological questions in mind. One emerging area of interest is to determine which genes are equivalently or inversely changed between different experiments. The equivalent change index (ECI) is a recently proposed metric that measures the extent to which a gene is equivalently or inversely regulated between two experiments. The goal of this work is to develop an algorithm that makes use of the ECI and powerful network analysis techniques to identify a connected subset of genes that are highly relevant to the experimental conditions.

RESULTS

To address the above goal, we developed a method called Active Module identification using Experimental data and Network Diffusion (AMEND). The AMEND algorithm is designed to find a subset of connected genes in a PPI network that have large experimental values. It makes use of random walk with restart to create gene weights, and a heuristic solution to the Maximum-weight Connected Subgraph problem using these weights. This is performed iteratively until an optimal subnetwork (i.e., active module) is found. AMEND was compared to two current methods, NetCore and DOMINO, using two gene expression datasets.

CONCLUSION

The AMEND algorithm is an effective, fast, and easy-to-use method for identifying network-based active modules. It returned connected subnetworks with the largest median ECI by magnitude, capturing distinct but related functional groups of genes. Code is freely available at https://github.com/samboyd0/AMEND .

The emerging role of long noncoding RNA in depression and its implications in diagnostics and therapeutic responses

Depression is one of the most common mental illnesses, affecting more than 350 million people worldwide. However, the occurrence of depression is a complex process involving genetic, physiological, psychological, and social factors, and the underlying mechanisms of its pathogenesis remain unclear. With advances in sequencing technology and epigenetic studies, increasing research evidence suggests that long noncoding RNAs (lncRNAs) play nonnegligible roles in the development of depression and may be involved in the pathogenesis of depression through multiple pathways, including regulating neurotrophic factors and other growth factors and affecting synaptic function. In addition, significant alterations in lncRNA expression profiles in peripheral blood and different brain regions of patients and model animals with depression suggest that lncRNAs may function as biomarkers for the differential diagnosis of depression and other psychiatric disorders and may also be potential therapeutic targets. In this paper, the biological functions of lncRNAs are briefly described, and the functional roles and abnormal expression of lncRNAs in the development, diagnosis and treatment of depression are reviewed.

5HT1AR-FGFR1 Heteroreceptor Complexes Differently Modulate GIRK Currents in the Dorsal Hippocampus and the Dorsal Raphe Serotonin Nucleus of Control Rats and of a Genetic Rat Model of Depression

The midbrain raphe serotonin (5HT) neurons provide the main ascending serotonergic projection to the forebrain, including hippocampus, which has a role in the pathophysiology of depressive disorder. Serotonin 5HT1A receptor (R) activation at the soma-dendritic level of serotonergic raphe neurons and glutamatergic hippocampal pyramidal neurons leads to a decrease in neuronal firing by activation of G protein-coupled inwardly-rectifying potassium (GIRK) channels. In this raphe-hippocampal serotonin neuron system, the existence of 5HT1AR-FGFR1 heteroreceptor complexes has been proven, but the functional receptor-receptor interactions in the heterocomplexes have only been investigated in CA1 pyramidal neurons of control Sprague Dawley (SD) rats. In the current study, considering the impact of the receptor interplay in developing new antidepressant drugs, the effects of 5HT1AR-FGFR1 complex activation were investigated in hippocampal pyramidal neurons and in midbrain dorsal raphe serotonergic neurons of SD rats and of a genetic rat model of depression (the Flinders Sensitive Line (FSL) rats of SD origin) using an electrophysiological approach. The results showed that in the raphe-hippocampal 5HT system of SD rats, 5HT1AR-FGFR1 heteroreceptor activation by specific agonists reduced the ability of the 5HT1AR protomer to open the GIRK channels through the allosteric inhibitory interplay produced by the activation of the FGFR1 protomer, leading to increased neuronal firing. On the contrary, in FSL rats, FGFR1 agonist-induced inhibitory allosteric action at the 5HT1AR protomer was not able to induce this effect on GIRK channels, except in CA2 neurons where we demonstrated that the functional receptor-receptor interaction is needed for producing the effect on GIRK. In keeping with this evidence, hippocampal plasticity, evaluated as long-term potentiation induction ability in the CA1 field, was impaired by 5HT1AR activation both in SD and in FSL rats, which did not develop after combined 5HT1AR-FGFR1 heterocomplex activation in SD rats. It is therefore proposed that in the genetic FSL model of depression, there is a significant reduction in the allosteric inhibition exerted by the FGFR1 protomer on the 5HT1A protomer-mediated opening of the GIRK channels in the 5HT1AR-FGFR1 heterocomplex located in the raphe-hippocampal serotonin system. This may result in an enhanced inhibition of the dorsal raphe 5HT nerve cell and glutamatergic hippocampal CA1 pyramidal nerve cell firing, which we propose may have a role in depression.

Plausible Role of Stem Cell Types for Treating and Understanding the Pathophysiology of Depression

Major Depressive Disorder (MDD), colloquially known as depression, is a debilitating condition affecting an estimated 3.8% of the population globally, of which 5.0% are adults and 5.7% are above the age of 60. MDD is differentiated from common mood changes and short-lived emotional responses due to subtle alterations in gray and white matter, including the frontal lobe, hippocampus, temporal lobe, thalamus, striatum, and amygdala. It can be detrimental to a person’s overall health if it occurs with moderate or severe intensity. It can render a person suffering terribly to perform inadequately in their personal, professional, and social lives. Depression, at its peak, can lead to suicidal thoughts and ideation. Antidepressants manage clinical depression and function by modulating the serotonin, norepinephrine, and dopamine neurotransmitter levels in the brain. Patients with MDD positively respond to antidepressants, but 10–30% do not recuperate or have a partial response accompanied by poor life quality, suicidal ideation, self-injurious behavior, and an increased relapse rate. Recent research shows that mesenchymal stem cells and iPSCs may be responsible for lowering depression by producing more neurons with increased cortical connections. This narrative review discusses the plausible functions of various stem cell types in treating and understanding depression pathophysiology.

The FGF/FGFR system in the microglial neuroinflammation with Borrelia burgdorferi: likely intersectionality with other neurological conditions

BACKGROUND

Lyme neuroborreliosis, caused by the bacterium Borrelia burgdorferi affects both the central and peripheral nervous systems (CNS, PNS). The CNS manifestations, especially at later stages, can mimic/cause many other neurological conditions including psychiatric disorders, dementia, and others, with a likely neuroinflammatory basis. The pathogenic mechanisms associated with Lyme neuroborreliosis, however, are not fully understood.

METHODS

In this study, using cultures of primary rhesus microglia, we explored the roles of several fibroblast growth factor receptors (FGFRs) and fibroblast growth factors (FGFs) in neuroinflammation associated with live B. burgdorferi exposure. FGFR specific siRNA and inhibitors, custom antibody arrays, ELISAs, immunofluorescence and microscopy were used to comprehensively analyze the roles of these molecules in microglial neuroinflammation due to B. burgdorferi.

RESULTS

FGFR1-3 expressions were upregulated in microglia in response to B. burgdorferi. Inhibition of FGFR 1, 2 and 3 signaling using siRNA and three different inhibitors showed that FGFR signaling is proinflammatory in response to the Lyme disease bacterium. FGFR1 activation also contributed to non-viable B. burgdorferi mediated neuroinflammation. Analysis of the B. burgdorferi conditioned microglial medium by a custom antibody array showed that several FGFs are induced by the live bacterium including FGF6, FGF10 and FGF12, which in turn induce IL-6 and/or CXCL8, indicating a proinflammatory nature. To our knowledge, this is also the first-ever described role for FGF6 and FGF12 in CNS neuroinflammation. FGF23 upregulation, in addition, was observed in response to the Lyme disease bacterium. B. burgdorferi exposure also downregulated many FGFs including FGF 5, 7, 9, 11, 13, 16, 20 and 21. Some of the upregulated FGFs have been implicated in major depressive disorder (MDD) or dementia development, while the downregulated ones have been demonstrated to have protective roles in epilepsy, Parkinson's disease, Alzheimer's disease, spinal cord injury, blood-brain barrier stability, and others.

CONCLUSIONS

In this study we show that FGFRs and FGFs are novel inducers of inflammatory mediators in Lyme neuroborreliosis. It is likely that an unresolved, long-term (neuro)-Lyme infection can contribute to the development of other neurologic conditions in susceptible individuals either by augmenting pathogenic FGFs or by suppressing ameliorative FGFs or both.

Neurotrophic Factors and Dendritic Spines

Dendritic spines are highly dynamic structures that play important roles in neuronal plasticity. The morphologies and the numbers of dendritic spines are highly variable, and this diversity is correlated with the different morphological and physiological features of this neuronal compartment. Dendritic spines can change their morphology and number rapidly, allowing them to adapt to plastic changes. Neurotrophic factors play important roles in the brain during development. However, these factors are also necessary for a variety of processes in the postnatal brain. Neurotrophic factors, especially members of the neurotrophin family and the ephrin family, are involved in the modulation of long-lasting effects induced by neuronal plasticity by acting on dendritic spines, either directly or indirectly. Thereby, the neurotrophic factors play important roles in processes attributed, for example, to learning and memory.

Inflammatory Markers of Geriatric Depression Response to Tai Chi or Health Education Adjunct Interventions

BACKGROUND

Underlying inflammation is associated with an increased risk of depression in older adults. In this study, we examined the role of inflammatory biomarkers in antidepressant response in depressed older adults undergoing adjunct Tai Chi Chih (TCC) or Health education interventions.

METHODS

Older adults aged 60 years and above with a diagnosis of major depression were randomized to 12 weeks of TCC versus Health and Wellness Education (HEW) as an adjunct therapy to their stable antidepressant treatment regimen. A panel of 19 cytokine/chemokines was measured at baseline and 12 weeks. Five factors were derived using factor analysis. General linear models were estimated to examine the change in factor scores and the association of these changes on depression remission rates, controlling for age, sex, and body mass index.

RESULTS

Of the 170 randomized participants (TCC: n = 85 and HEW: n = 85), 55 TCC and 58 HEW completed the 3-month assessment. The groups did not differ at baseline in any measure. At follow-up, neither the changes in cytokine/chemokines scores nor the depression remission rate differed significantly between TCC and HEW. However, remitters and non-remitters differed significantly in changes in a factor composed of growth-regulated oncogene protein-alpha (GRO-alpha), epidermal growth factor (EGF), and soluble CD40 ligand (sCD40L). GRO-alpha and EGF levels (in both groups) were significantly increased in remitters compared to non-remitters.

CONCLUSION

Changes in certain cytokines/chemokines may accompany improvement in depressive symptoms in older adults. Future studies will need to explore the role of these molecules in remission of late-life depression.

Heterogeneity in major depressive disorder: The need for biomarker-based personalized treatments

Major Depressive Disorder (MDD) or depression is a pathological mental condition affecting millions of people worldwide. Identification of objective biological markers of depression can provide for a better diagnostic and intervention criteria; ultimately aiding to reduce its socioeconomic health burden. This review provides a comprehensive insight into the major biomarker candidates that have been implicated in depression neurobiology. The key biomarker categories are covered across all the "omics" levels. At the epigenomic level, DNA-methylation, non-coding RNA and histone-modifications have been discussed in relation to depression. The proteomics system shows great promise with inflammatory markers as well as growth factors and neurobiological alterations within the endocannabinoid system. Characteristic lipids implicated in depression together with the endocrine system are reviewed under the metabolomics section. The chapter also examines the novel biomarkers for depression that have been proposed by studies in the microbiome. Depression affects individuals differentially and explicit biomarkers identified by robust research criteria may pave the way for better diagnosis, intervention, treatment, and prediction of treatment response.

The protective effects of curcumin on depression: Genes, transcription factors, and microRNAs involved

BACKGROUND

We aim to identify the molecular mechanisms for curcumin's anti-depressant properties, including genes, transcription factors, and miRNAs.

METHODS

The Comparative Toxicogenomics Database, GeneMania, Metascape, MIENTURNET, and Cytoscape software were used as important data approaches in this study.

RESULTS

Curcumin may have an anti-depressant effect via the relevant genes: ADORA2A, ALB, BDNF, FGF2, GLO1, GSK3B, IL6, MIF, NOS1, PTGS2, RELN, SELP, SOD1, and NR3C1. Co-expression (50.7 %) and physical interactions (28.7 %) were the primary relationships discovered by gene network analysis. The key pathways involved in curcumin's protective function against depression were "spinal cord injury", "regulation of apoptotic signaling pathway", "positive regulation of protein phosphorylation", "folate metabolism", "neuroinflammation and glutamatergic signaling", and "inflammation response". We also observed 74 miRNAs associated with depression that are targeted by curcumin, with hsa-miR-146a-5p having the greatest expression and interaction. PLSCR1, SNAI1, ZNF267, ATF3, and GTF2B were the most important transcription factors that regulated four curcumin-targeted genes. Curcumin's physicochemical characteristics and pharmacokinetics are consistent with its antidepressant effects due to its high gastrointestinal absorption, which did not remove it from the CNS, and its ability to penetrate the blood-brain barrier. Curcumin also inhibits CYP1A9 and CYP3A4.

LIMITATIONS

A toxicogenomic design in silico was applied.

CONCLUSIONS

Our findings suggest that therapy optimization and further research into curcumin's pharmacological properties are required before it may be utilized to treat depression.

Chronic fluoxetine enhances extinction therapy for PTSD by evaluating brain glucose metabolism in rats: an [18F]FDG PET study

BACKGROUND

Recent studies suggest that selective serotonin reuptake inhibitors (SSRIs) and exposure therapies have been used to reduced footshock-induced posttraumatic stress disorder (PTSD) symptoms. However, the therapeutic effect of the combination of SSRIs treatment with exposure therapy remains a matter of debate. This study aimed to evaluate these therapeutic effect through the behavioural and the neuroimaging changes by positron emission tomography (PET) in model rats.

METHODS

Pavlovian fear conditioning paradigm to establish model rats, and serial PET imaging with 2-deoxy-2-[¹⁸F]fluoro-D-glucose ([¹⁸F]FDG) was performed during the control, fear-conditioning, and extinction-retrieval phases. The expression of c-Fos was used to identify neural activity.

RESULTS

We report that fear conditioning increased glucose metabolism in the right amygdala and left primary visual cortex but decreased glucose metabolism in the left primary somatosensory cortex. After extinction retrieval, there was increased [¹⁸F]FDG uptake in the left striatum, left cochlear nucleus and right primary visual cortex but decreased uptake in the anterior cingulate cortex in the extinction group. Fluoxetine increased [¹⁸F]FDG uptake in the left hippocampus and right primary visual cortex but decreased uptake in the bilateral primary somatosensory cortex, left primary/secondary motor cortex and cuneiform nucleus. The combined therapy increased [¹⁸F]FDG uptake in the left hippocampus, left striatum, right insular cortex, left posterior parietal cortex, and right secondary visual cortex but reduced uptake in the cerebellar lobule. c-Fos expression in the hippocampal dentate gyrus and anterior cingulate cortex in the fluoxetine and combined groups was significantly higher than that in the extinction group, with no significant difference between the two groups.

CONCLUSIONS

Chronic fluoxetine enhanced the effects of extinction training in a rat model of PTSD. In vivo PET imaging may provide a promising approach for evaluation chronic fluoxetine treatment of PTSD.

Multiple roles of neuronal extracellular vesicles in neurological disorders

Neuropathy is a growing public health problem in the aging, adolescent, and sport-playing populations, and the number of individuals at risk of neuropathy is growing; its risks include aging, violence, and conflicts between players. The signal pathways underlying neuronal aging and damage remain incompletely understood and evidence-based treatment for patients with neuropathy is insufficiently delivered; these are two of the reasons that explain why neuropathy is still not completely curable and why the progression of the disease cannot be inhibited. Extracellular vesicles (EVs) shuttling is an important pathway in disease progression. Previous studies have focused on the EVs of cells that support and protect neurons, such as astrocytes and microglia. This review aims to address the role of neuronal EVs by delineating updated mechanisms of neuronal damage and summarizing recent findings on the function of neuronal EVs. Challenges and obstacles in isolating and analyzing neuronal EVs are discussed, with an emphasis on neuron as research object and modification of EVs on translational medicine.

Proteins associated with future suicide attempts in bipolar disorder: A large-scale biomarker discovery study

Suicide is a major cause of death worldwide. Several biological systems have been implicated in suicidal behavior but studies of candidate biomarkers have failed to produce clinically relevant biomarkers for suicide prediction. The objective of the present study was to identify novel candidate biomarkers for suicidal behavior. We used a nested case-control study design where a large cohort of patients with bipolar disorder (N = 5 110) were followed up to 8 years after blood sampling. We included patients that attempted suicide during follow-up (N = 348) and matched bipolar disorder patients from the same cohort who did not attempt suicide during the study period (N = 348) and analyzed a total of 92 proteins with a neuro exploratory multiplex panel. Using a multivariate classification algorithm devised to minimize bias in variable selection, we identified a parsimonious set of proteins that best discriminated bipolar disorder patients with and without prospective suicide attempts. The algorithm selected 16 proteins for the minimal-optimal classification model, which outperformed 500 models with permuted outcome (p = 0.0004) but had low sensitivity (53%) and specificity (64%). The candidate proteins were then entered in separate logistic regression models to calculate protein-specific associations with prospective suicide attempts. In individual analyses, three of these proteins were significantly associated with prospective suicide attempt (SCGB1A1, ANXA10, and CETN2). Most of the candidate proteins are novel to suicide research.

Serum Klotho and FGF23 Levels in Patients with Schizophrenia

Background

The aim of this study is to compare the serum levels of Klotho and fibroblast growth factor 23 in patients with schizophrenia, in whom etiopathogenesis inflammation plays an important role, with those of healthy control subjects and to investigate a possible correlation between these levels.

Methods

Forty male patients with schizophrenia and 40 healthy male control subjects who were followed up and/or treated at the High-Security Forensic Psychiatry Clinic participated in the study. Sociodemographic data form, the Positive and Negative Syndrome Scale, and the Clinical Global Impression Scale were collected from all subjects, and participants' fibroblast growth factor 23 and Klotho serum levels were measured by the enzyme-linked immunosorbent assay method.

Results

The serum levels of Klotho and fibroblast growth factor 23 were significantly higher in schizophrenia patients than in healthy controls (P  = .048 and P  = .010, respectively). A significant positive correlation was observed between serum levels of Klotho and fibroblast growth factor 23 in subjects (r = 0.816; P  < .001).

Conclusion

Our study is the first to show significantly higher combined serum levels of fibroblast growth factor 23 and Klotho in patients with schizophrenia. The Klotho/fibroblast growth factor 23 pathway may play a role in the pathogenesis of schizophrenia. The involvement of Klotho and fibroblast growth factor 23 in inflammatory processes has the potential to provide alternative approaches to elucidate the etiopathogenesis and treatment of schizophrenia.

Antidepressant-like effects of trophic factor receptor signaling

A significant body of research has demonstrated that antidepressants regulate neurotrophic factors and that neurotrophins themselves are capable of independently producing antidepressant-like effects. While brain derived neurotrophic factor (BDNF) remains the best studied molecule in this context, there are several structurally diverse trophic factors that have shown comparable behavioral effects, including basic fibroblast growth factor (FGF-2), insulin-like growth factor 1 (IGF-1) and vascular endothelial growth factor (VEGF). In this review we discuss the structural and biochemical signaling aspects of these neurotrophic factors with antidepressant activity. We also include a discussion on a cytokine molecule erythropoietin (EPO), widely known and prescribed as a hormone to treat anemia but has recently been shown to function as a neurotrophic factor in the central nervous system (CNS).

Evidence for an allostatic epigenetic memory on chromatin footprints after double-hit acute stress

Stress induces allostatic responses, whose limits depend on genetic background and the nature of the challenges. Allostatic load reflects the cumulation of these reponses over the course of life. Acute stress is usually associated with adaptive responses, although, depending on the intensity of the stress and individual differences , some may experience maladaptive coping that persists through life and may influence subsequent responses to stressful events, as is the case of post-traumatic stress disorder. We investigated the behavioral traits and epigenetic signatures in a double-hit mouse model of acute stress in which heterotypic stressors (acute swim stress and acute restraint stress) were applied within a 7-day interval period. The ventral hippocampus was isolated to study the footprints of chromatin accessibility driven by exposure to double-hit stress. Using ATAC sequencing to determine regions of open chromatin, we showed that depending on the number of acute stressors, several gene sets related to development, immune function, cell starvation, translation, the cytoskeleton, and DNA modification were reprogrammed in both males and females. Chromatin accessibility for transcription factor binding sites showed that stress altered the accessibility for androgen, glucocorticoid, and mineralocorticoid receptor binding sites (AREs/GREs) at the genome-wide level, with double-hit stressed mice displaying a profile unique from either single hit of acute stress. The investigation of AREs/GREs adjacent to gene coding regions revealed several stress-related genes, including Fkbp5, Zbtb16, and Ddc, whose chromatin accessibility was affected by prior exposure to stress. These data demonstrate that acute stress is not truly acute because it induces allostatic signatures that persist in the epigenome and may manifest when a second challenge hits later in life.

Acute Ethanol Challenge Differentially Regulates Expression of Growth Factors and miRNA Expression Profile of Whole Tissue of the Dorsal Hippocampus

Acute ethanol exposure produces rapid alterations in neuroimmune gene expression that are both time- and cytokine-dependent. Interestingly, adolescent rats, who often consume binge-like quantities of alcohol, displayed reduced neuroimmune responses to acute ethanol challenge. However, it is not known whether growth factors, a related group of signaling factors, respond to ethanol similarly in adults and adolescents. Therefore, Experiment 1 aimed to assess the growth factor response to ethanol in both adolescents and adults. To test this, adolescent (P29-P34) and adult (P70-P80) Sprague Dawley rats of both sexes were injected with either ethanol (3.5 g/kg) or saline, and brains were harvested 3 h post-injection for assessment of growth factor, cytokine, or miRNA expression. As expected, acute ethanol challenge significantly increased IL-6 and IκBα expression in the hippocampus and amygdala, replicating our prior findings. Acute ethanol significantly decreased BDNF and increased FGF2 regardless of age condition. PDGF was unresponsive to ethanol, but showed heightened expression among adolescent males. Because recent work has focused on the PDE4 inhibitor ibudilast for treatment in alcohol use disorder, Experiment 2 tested whether ibudilast would alter ethanol-evoked gene expression changes in cytokines and growth factors in the CNS. Ibudilast (9.0 mg/kg s.c.) administration 1 h prior to ethanol had no effect on ethanol-induced changes in cytokine or growth factor changes in the hippocampus or amygdala. To further explore molecular alterations evoked by acute ethanol challenge in the adult rat hippocampus, Experiment 3 tested whether acute ethanol would change the miRNA expression profile of the dorsal hippocampus using RNASeq, which revealed a rapid suppression of 12 miRNA species 3 h after acute ethanol challenge. Of the miRNA affected by ethanol, the majority were related to inflammation or cell survival and proliferation factors, including FGF2, MAPK, NFκB, and VEGF. Overall, these findings suggest that ethanol-induced, rapid alterations in neuroimmune gene expression were (i) muted among adolescents; (ii) independent of PDE4 signaling; and (iii) accompanied by changes in several growth factors (increased FGF2, decreased BDNF). In addition, ethanol decreased expression of multiple miRNA species, suggesting a dynamic molecular profile of changes in the hippocampus within a few short hours after acute ethanol challenge. Together, these findings may provide important insight into the molecular consequences of heavy drinking in humans.

Neurotrophic Factor-α1/Carboxypeptidase E Functions in Neuroprotection and Alleviates Depression

Depression is a major psychiatric disease affecting all ages and is often co-morbid with neurodegeneration in the elderly. Depression and neurodegeneration are associated with decreased neurotrophic factors. In this mini-review the functions and potential therapeutic use of a newly discovered trophic factor, Neurotrophic factor-α1 (NF-α1), also known as Carboxypeptidase E (CPE), in depression and neuroprotection are discussed. NF-α1/CPE expression is enriched in CA3 neurons of the hippocampus. Families carrying null and homozygous non-sense mutations of the NF-α1/CPE gene share common clinical features including childhood onset obesity, type 2 diabetes, impaired intellectual abilities and hypogonadotrophic hypogonadism. Studies in animal models such as CPE knockout (KO) mice and CPEfat/fat mutant mice exhibit similar phenotypes. Analysis of CPE-KO mouse brain revealed that hippocampal CA3 was completely degenerated after weaning stress, along with deficits in hippocampal long-term potentiation. Carbamazepine effectively blocked weaning stress-induced hippocampal CA3 degeneration, suggesting the stress induced epileptic-like neuronal firing led to the degeneration. Analysis of possible mechanisms underlying NF-α1/CPE -mediated neuroprotection revealed that it interacts with the serotonin receptor, 5-HTR1E, and via β arrestin activation, subsequently upregulates ERK1/2 signaling and pro-survival protein, BCL2, levels. Furthermore, the NF-α1/CPE promoter contains a peroxisome proliferator-activated receptor (PPARγ) binding site which can be activated by rosiglitazone, a PPARγ agonist, to up-regulate expression of NF-α1/CPE and neurogenesis, resulting in anti-depression in animal models. Rosiglitazone, an anti-diabetic drug administered to diabetic patients resulted in decline of depression. Thus, NF-α1/CPE is a potential therapeutic agent or drug target for treating depression and neurodegenerative disorders.

Sex-Specific Brain Transcriptional Signatures in Human MDD and Their Correlates in Mouse Models of Depression

Major depressive disorder (MDD) is amongst the most devastating psychiatric conditions affecting several millions of people worldwide every year. Despite the importance of this disease and its impact on modern societies, still very little is known about the etiological mechanisms. Treatment strategies have stagnated over the last decades and very little progress has been made to improve the efficiency of current therapeutic approaches. In order to better understand the disease, it is necessary for researchers to use appropriate animal models that reproduce specific aspects of the complex clinical manifestations at the behavioral and molecular levels. Here, we review the current literature describing the use of mouse models to reproduce specific aspects of MDD and anxiety in males and females. We first describe some of the most commonly used mouse models and their capacity to display unique but also shared features relevant to MDD. We then transition toward an integral description, combined with genome-wide transcriptional strategies. The use of these models reveals crucial insights into the molecular programs underlying the expression of stress susceptibility and resilience in a sex-specific fashion. These studies performed on human and mouse tissues establish correlates into the mechanisms mediating the impact of stress and the extent to which different mouse models of chronic stress recapitulate the molecular changes observed in depressed humans. The focus of this review is specifically to highlight the sex differences revealed from different stress paradigms and transcriptional analyses both in human and animal models.

Characterization of cell-cell communication in autistic brains with single-cell transcriptomes

BACKGROUND

Autism spectrum disorder is a neurodevelopmental disorder, affecting 1-2% of children. Studies have revealed genetic and cellular abnormalities in the brains of affected individuals, leading to both regional and distal cell communication deficits.

METHODS

Recent application of single-cell technologies, especially single-cell transcriptomics, has significantly expanded our understanding of brain cell heterogeneity and further demonstrated that multiple cell types and brain layers or regions are perturbed in autism. The underlying high-dimensional single-cell data provides opportunities for multilevel computational analysis that collectively can better deconvolute the molecular and cellular events altered in autism. Here, we apply advanced computation and pattern recognition approaches on single-cell RNA-seq data to infer and compare inter-cell-type signaling communications in autism brains and controls.

RESULTS

Our results indicate that at a global level, there are cell-cell communication differences in autism in comparison with controls, largely involving neurons as both signaling senders and receivers, but glia also contribute to the communication disruption. Although the magnitude of changes is moderate, we find that excitatory and inhibitor neurons are involved in multiple intercellular signaling that exhibits increased strengths in autism, such as NRXN and CNTN signaling. Not all genes in the intercellular signaling pathways show differential expression, but genes in the affected pathways are enriched for axon guidance, synapse organization, neuron migration, and other critical cellular functions. Furthermore, those genes are highly connected to and enriched for genes previously associated with autism risks.

CONCLUSIONS

Overall, our proof-of-principle computational study using single-cell data uncovers key intercellular signaling pathways that are potentially disrupted in the autism brains, suggesting that more studies examining cross-cell type effects can be valuable for understanding autism pathogenesis.

High-frequency repetitive transcranial magnetic stimulation mitigates depression-like behaviors in CUMS-induced rats via FGF2/FGFR1/p-ERK signaling pathway

High-frequency repetitive transcranial magnetic stimulation (rTMS) is a widely used and effective biological treatment for depression. Although previous studies have shown that astrocyte function may be modified by rTMS, the specific neurobiological mechanisms underlying its antidepressant action are not clear. Substantial evidence has accumulated indicating that neurotrophin dysfunction and neuronal apoptosis play a role in the development of depression. To evaluate this hypothesis, we applied a chronical unpredictable mild stress (CUMS) protocol to induce depression-like behaviors in rats, followed by the delivery of 10-Hz rTMS for 3 weeks. Behavioral outcome measures consisted of a sucrose preference test, forced swimming test, and open field test. Histological analysis focused on apoptosis, expression of GFAP and FGF2, and FGF2 pathway-related proteins. The results showed that after rTMS treatment, the rats' sucrose preference increased, open field performance improved while the immobility time of forced swimming decreased. The behavioral changes seen in rTMS treated rats were accompanied by marked reductions in the number of TUNEL-positive neural cells and the level of expression of BAX and by an increase in Bcl2. Furthermore, the expression of GFAP and FGF2 was increased, along with activation of FGF2 downstream pathway. These results suggest that rTMS treatment can improve depression-like behavior, attenuate neural apoptosis, and reverse reduction of astrocytes in a rat model of depression. We hypothesize that the therapeutic action of rTMS in CUMS-induced rats is linked to the activation of the FGF2/FGFR1/p-ERK signaling pathway.

Fibroblast Growth Factor 9 as a Potential Biomarker for Schizophrenia

Preclinical and clinical studies have suggested that fibroblast growth factor (FGF) system contributed to the onset and development of schizophrenia (SCZ). However, there was no strong clinical evidence to link an individual FGF with SCZ. In this study, we aim to measure blood FGF9 levels in the patients with SCZ with and/or without medication, and test whether FGF9 has a potential to be a biomarker for SCZ. We recruited 130 patients with SCZ and 111 healthy individuals, and the ELISA and qRT-PCR assays were used to measure serum FGF9 levels in the participants. ELISA assay demonstrated that serum FGF9 protein levels were dramatically reduced in first-episode, drug-free patients, but not in chronically medicated patients when compared to healthy control subjects. Further analysis showed that treatment of the first-episode, drug-free SCZ patients with antipsychotics for 8 weeks significantly increased the serum FGF9 levels. In addition, we found that blood FGF9 mRNA levels were significantly lower in first-onset SCZ patients than controls. Under the receiver operating characteristic curve, the optimal cutoff values for FGF9 protein level as an indicator for diagnosis of drug-free SCZ patients was projected to be 166.4 pg/ml, which yielded a sensitivity of 0.955 and specificity of 0.86, and the area under the curve was 0.973 (95% CI, 0.954-0.993). Furthermore, FGF9 had good performance to discriminate between drug-free SCZ patients and chronically medicated patients, the optimal cutoff value for FGF9 concentration was projected to be 165.035 pg/ml with a sensitivity of 0.86 and specificity of 0.919, and the AUC was 0.968 (95% CI, 0.944, 0.991). Taken together, our results for the first time demonstrated the dysregulation of FGF9 in SCZ, and FGF9 has the potential to be served as a biomarker for SCZ.

Leukocyte methylomic imprints of exposure to the genocide against the Tutsi in Rwanda: a pilot epigenome-wide analysis

Aim & methods: We conducted a pilot epigenome-wide association study of women from Tutsi ethnicity exposed to the genocide while pregnant and their resulting offspring, and a comparison group of women who were pregnant at the time of the genocide but living outside of Rwanda.Results: Fifty-nine leukocyte-derived DNA samples survived quality control: 33 mothers (20 exposed, 13 unexposed) and 26 offspring (16 exposed, 10 unexposed). Twenty-four significant differentially methylated regions (DMRs) were identified in mothers and 16 in children. Conclusions:In utero genocide exposure was associated with CpGs in three of the 24 DMRs: BCOR, PRDM8 and VWDE, with higher DNA methylation in exposed versus unexposed offspring. Of note, BCOR and VWDE show significant correlation between brain and blood DNA methylation within individuals, suggesting these peripherally derived signals of genocide exposure may have relevance to the brain.

Large-Scale Transcriptomics Studies Provide Insight Into Sex Differences in Depression

Major depressive disorder (MDD) is a leading cause of disability, affecting more than 300 million people worldwide. We first review the well-known sex difference in incidence of MDD, with women being twice as likely to be diagnosed as men, and briefly summarize how the impact of MDD varies between men and women, with sex differences in symptoms, severity, and antidepressant drug response. We then attempt to deconstruct the biological bases for MDD and discuss implications for sex differences research. Next, we review findings from human postmortem studies, both from selected candidate gene studies and from well-powered, unbiased transcriptomics studies, which suggest distinct, and possibly opposite, molecular changes in the brains of depressed men and women. We then discuss inherent challenges of research on the human postmortem brain and suggest paths forward that rely on thoughtful cohort design. Although studies indicate that circulating gonadal hormones might underlie the observed sex differences in MDD, we discuss how additional sex-specific factors, such as genetic sex and developmental exposure to gonadal hormones, may also contribute to altered vulnerability, and we highlight various nuances that we believe should be considered when determining mechanisms underlying observed sex differences. Altogether, this review highlights not only how various sex-specific factors might influence susceptibility or resilience to depression, but also how those sex-specific factors might result in divergent pathology in men and women.

The Association Between Salivary FGF2 and Physiological and Psychological Components of the Human Stress Response

Background

Fibroblast Growth Factor 2 (FGF2) is a neurotrophic protein that has been implicated as a biomarker for anxiety and depressive disorders, which comprise a significant component of the global burden of disease. Research using rodents has indicated that FGF2 is part of the stress response, but whether this translates to humans has yet to be investigated. In this study, we aimed to explore the potential role of FGF2 in the human stress response by examining its association with physiological and psychological processes during and following the Trier Social Stress Test (TSST).

Methods

Participants in the active stress experiment (N  =  87) underwent the TSST, provided saliva samples to obtain levels of cortisol and FGF2, and reported on post-event rumination related to the TSST task over the following week. Participants in the no-stress experiment (N  =  25) provided saliva samples for measurement of FGF2 and cortisol across a corresponding time period.

Results

Salivary FGF2 levels changed after the TSST and were associated with the pattern of change in salivary cortisol. Cortisol responses in the active stress condition were blunted in females (relative to males), however, sex did not interact with any other effect. FGF2 reactivity (ie, the magnitude of change over time) was not correlated with cortisol reactivity. Lower FGF2 reactivity following the TSST, but not overall FGF2 levels, or cortisol, was associated with higher fear of negative evaluation, repetitive negative thinking and post-event processing, as well as repetitive negative thinking in the week following the TSST. Participants in the no-stress experiment showed a decrease in cortisol, yet no change in their FGF2 levels.

Conclusion

These findings suggest that FGF2 is involved in the human stress response and higher levels of FGF2 reactivity may be associated with protective cognitive processes following stress exposure.

Use of the PsycheMERGE Network to Investigate the Association Between Depression Polygenic Scores and White Blood Cell Count

Importance

Although depression is a common psychiatric disorder, its underlying biological basis remains poorly understood. Pairing depression polygenic scores with the results of clinical laboratory tests can reveal biological processes involved in depression etiology and in the physiological changes resulting from depression.

Objective

To characterize the association between depression polygenic scores and an inflammatory biomarker, ie, white blood cell count.

Design, Setting, and Participants

This genetic association study was conducted from May 19, 2019, to June 5, 2021, using electronic health record data from 382 452 patients across 4 health care systems. Analyses were conducted separately in each health care system and meta-analyzed across all systems. Primary analyses were conducted in Vanderbilt University Medical Center's biobank. Replication analyses were conducted across 3 other PsycheMERGE sites: Icahn School of Medicine at Mount Sinai, Mass General Brigham, and the Million Veteran Program. All patients with available genetic data and recorded white blood cell count measurements were included in the analyses. Primary analyses were conducted in individuals of European descent and then repeated in a population of individuals of African descent.

Exposures

Depression polygenic scores.

Main Outcomes and Measures

White blood cell count.

Results

Across the 4 PsycheMERGE sites, there were 382 452 total participants of European ancestry (18.7% female; median age, 57.9 years) and 12 383 participants of African ancestry (61.1% female; median age, 39.0 [range, birth-90.0 years]). A laboratory-wide association scan revealed a robust association between depression polygenic scores and white blood cell count (β, 0.03; SE, 0.004; P = 1.07 × 10-17), which was replicated in a meta-analysis across the 4 health care systems (β, 0.03; SE, 0.002; P = 1.03 × 10-136). Mediation analyses suggested a bidirectional association, with white blood cell count accounting for 2.5% of the association of depression polygenic score with depression diagnosis (95% CI, 2.2%-20.8%; P = 2.84 × 10-70) and depression diagnosis accounting for 9.8% of the association of depression polygenic score with white blood cell count (95% CI, 8.4%-11.1%; P = 1.78 × 10-44). Mendelian randomization provided additional support for an association between increased white blood count and depression risk, but depression modeled as the exposure showed no evidence of an influence on white blood cell counts.

Conclusions and Relevance

This genetic association study found that increased depression polygenic scores were associated with increased white blood cell count, and suggests that this association may be bidirectional. These findings highlight the potential importance of the immune system in the etiology of depression and may motivate future development of clinical biomarkers and targeted treatment options for depression.

The Association Between Antidepressant Effect of SSRIs and Astrocytes: Conceptual Overview and Meta-analysis of the Literature

Major depressive disorders (MDD) a worldwide psychiatric disease, is yet to be adequately controlled by therapies; while the mechanisms of action of antidepressants are yet to be fully characterised. In the last two decades, an increasing number of studies have demonstrated the role of astrocytes in the pathophysiology and therapy of MDD. Selective serotonin reuptake inhibitors (SSRIs) are the most widely used antidepressants. It is generally acknowledged that SSRIs increase serotonin levels in the central nervous system by inhibiting serotonin transporters, although the SSRIs action is not ideal. The SSRIs antidepressant effect develops with considerable delay; their efficacy is low and frequent relapses are common. Neither cellular nor molecular pharmacological mechanisms of SSRIs are fully characterised; in particular their action on astrocytes remain underappreciated. In this paper we overview potential therapeutic mechanisms of SSRIs associated with astroglia and report the results of meta-analysis of studies dedicated to MDD, SSRIs and astrocytes. In particular, we argue that fluoxetine, the representative SSRI, improves depressive-like behaviours in animals treated with chronic mild stress and reverses depression-associated decrease in astrocytic glial fibrillary acidic protein (GFAP) expression. In addition, fluoxetine upregulates astrocytic mRNA expression of 5-hydroxytriptamin/serotonin2B receptors (5-HT2BR). In summary, we infer that SSRIs exert their anti-depressant effect by regulating several molecular and signalling pathways in astrocytes.

Adult brain cytogenesis in the context of mood disorders: From neurogenesis to the emergent role of gliogenesis

Psychiatric disorders severely impact patients' lives. Motivational, cognitive and emotional deficits are the most common symptoms observed in these patients and no effective treatment is still available, either due to the adverse side effects or the low rate of efficacy of currently available drugs. Neurogenesis recovery has been one important focus in the treatment of psychiatric disorders, which undeniably contributes to the therapeutic action of antidepressants. However, glial plasticity is emerging as a new strategy to explore the deficits observed in mood disorders and the efficacy of therapeutic interventions. Thus, it is crucial to understand the mechanisms behind glio- and neurogenesis to better define treatments and preventive therapies, once adult cytogenesis is of pivotal importance to cognitive and emotional components of behavior, both in healthy and pathological contexts, including in psychiatric disorders. Here, we review the concepts and history of neuro- and gliogenesis, providing as well a reflection on the functional importance of cytogenesis in the context of disease.

The Role of Fgf9 in the Antidepressant Effects of Exercise and Fluoxetine in Chronic Unpredictable Mild Stress Mice

OBJECTIVE

The neurotrophic hypothesis of depression posits that stress and depression decrease neurotrophic factor expression in brain, whereas antidepressants and exercise can contribute to the blockade of stress effects and produce antidepressant effects. Fibroblast growth factor 9 (FGF9), a member of the fibroblast growth factor (FGF) family, has been reported to be dysregulated in depression. The present study aimed to determine whether and how Fgf9 mediates the antidepressant effects of fluoxetine and exercise in chronic unpredictable mild stress (CUMS) mice.

METHODS

Male C57BL/6 mice were exposed to CUMS for 7 weeks. From the fourth week, CUMS-exposed mice were subjected to fluoxetine treatment or swimming exercise for 4 weeks. Forced swim test, tail suspension test, and hole-board test were used to assess behaviors of mice. Real-time polymerase chain reaction was used to examine hippocampal messenger RNA levels of Fgf9, Fgf2, FgfR1, FgfR2, and FgfR3. Western blotting was used to examine the protein levels of Fgf9, protein kinase B (Akt), and phosphorylation of Akt at Ser473 in mouse hippocampus.

RESULTS

Our results demonstrated that CUMS induced depression-like behaviors, which were reversed by fluoxetine treatment and swimming exercise. Moreover, we found that CUMS resulted in a dysregulation of Fgf9, Fgf2, and FgfR2 expression, whereas fluoxetine and swimming restored the FGF expression in CUMS-exposed mice. An analysis of the proteins suggests that the antidepressant effects of fluoxetine and exercise in CUMS-exposed mice were associated with ameliorated Fgf9/Akt signaling.

CONCLUSIONS

Our findings have demonstrated that swimming exercise mimics the antidepressant effects of fluoxetine by regulating Fgf9 in CUMS-exposed mice, which may offer new mechanism-based therapeutic targets for depression.

Fibroblast Growth Factor Signalling in the Diseased Nervous System

Fibroblast growth factors (FGFs) act as key signalling molecules in brain development, maintenance, and repair. They influence the intricate relationship between myelinating cells and axons as well as the association of astrocytic and microglial processes with neuronal perikarya and synapses. Advances in molecular genetics and imaging techniques have allowed novel insights into FGF signalling in recent years. Conditional mouse mutants have revealed the functional significance of neuronal and glial FGF receptors, not only in tissue protection, axon regeneration, and glial proliferation but also in instant behavioural changes. This review provides a summary of recent findings regarding the role of FGFs and their receptors in the nervous system and in the pathogenesis of major neurological and psychiatric disorders.

ADGRL3, FGF1 and DRD4: Linkage and Association with Working Memory and Perceptual Organization Candidate Endophenotypes in ADHD

Attention deficit hyperactivity disorder (ADHD) is a highly heritable neurobehavioral disorder that affects children worldwide, with detrimental long-term consequences in affected individuals. ADHD-affected patients display visual-motor and visuospatial abilities and skills that depart from those exhibited by non-affected individuals and struggle with perceptual organization, which might partially explain impulsive responses. Endophenotypes (quantifiable or dimensional constructs that are closely related to the root cause of the disease) might provide a more powerful and objective framework for dissecting the underlying neurobiology of ADHD than that of categories offered by the syndromic classification. In here, we explore the potential presence of the linkage and association of single-nucleotide polymorphisms (SNPs), harbored in genes implicated in the etiology of ADHD (ADGRL3, DRD4, and FGF1), with cognitive endophenotypes related to working memory and perceptual organization in 113 nuclear families. These families were ascertained from a geographical area of the Caribbean coast, in the north of Colombia, where the community is characterized by its ethnic diversity and differential gene pool. We found a significant association and linkage of markers ADGRL3-rs1565902, DRD4-rs916457 and FGF1-rs2282794 to neuropsychological tasks outlining working memory and perceptual organization such as performance in the digits forward and backward, arithmetic, similarities, the completion of figures and the assembly of objects. Our results provide strong support to understand ADHD as a combination of working memory and perceptual organization deficits and highlight the importance of the genetic background shaping the neurobiology, clinical complexity, and physiopathology of ADHD. Further, this study supplements new information regarding an ethnically diverse community with a vast African American contribution, where ADHD studies are scarce.

Elucidating the Possible Role of FoxO in Depression

Forkhead box-O (FoxO) transcriptional factors perform essential functions in several physiological and biological processes. Recent studies have shown that FoxO is implicated in the pathophysiology of depression. Changes in the upstream mediators of FoxOs including brain-derived neurotrophic factor (BDNF) and protein kinase B have been associated with depressive disorder and the antidepressant agents are known to alter the phosphorylation of FoxOs. Moreover, FoxOs might be regulated by serotonin or noradrenaline signaling and the hypothalamic-pituitary-adrenal (HPA)-axis,both of them are associated with the development of the depressive disorder. FoxO also regulates neural morphology, synaptogenesis, and neurogenesis in the hippocampus, which accounts for the pathogenesis of the depressive disorder. The current article underlined the potential functions of FoxOs in the etiology of depressive disorder and formulate few essential proposals for further investigation. The review also proposes that FoxO and its signal pathway might establish possible therapeutic mediators for the management of depressive disorder.

The effects of cocaine exposure in adolescence: Behavioural effects and neuroplastic mechanisms in experimental models

Drug addiction is a devastating disorder with a huge economic and social burden for modern society. Although an individual may slip into drug abuse throughout his/her life, adolescents are at higher risk, but, so far, only a few studies have attempted to elucidate the underlying cellular and molecular bases of such vulnerability. Indeed, preclinical evidence indicates that psychostimulants and adolescence interact and contribute to promoting a dysfunctional brain. In this review, we have focused our attention primarily on changes in neuroplasticity brought about by cocaine, taking into account that there is much less evidence from exposure to cocaine in adolescence, compared with that from adults. This review clearly shows that exposure to cocaine during adolescence, acute or chronic, as well as contingent or non‐contingent, confers a vulnerable endophenotype, primarily, by causing changes in neuroplasticity. Given the close relationship between drug abuse and psychiatric disorders, we also discuss the translational implications providing an interpretative framework for clinical studies involving addictive as well as affective or psychotic behaviours.

Cannabinoid CB1 and CB2 receptors differentially regulate TNF-α-induced apoptosis and LPA1-mediated pro-survival signaling in HT22 hippocampal cells

AIMS

The aim of the study was to investigate the interaction between cannabinoid CB₁/CB₂ and lysophosphatidic acid (LPA) receptors in controlling neuronal signaling and fate.

METHODS

HT22 hippocampal cells were treated with different cannabinoid and LPA receptor agonists and antagonists. Western blot and immunofluorescence microscopy were used to study intracellular signaling and the expression of apoptotic markers. Cell viability was determined by a luminescence assay.

KEY FINDINGS

Cannabinoid agonists induced activation of both ERK1/2 and p38 MAP kinases. The effects of the CB₁/CB₂ receptor agonist HU210 were antagonized by the CB₁ antagonist rimonabant, whereas the responses to the CB₂ agonist JWH133 were blocked by the CB₂ antagonist SR144528. HU210 reduced the apoptotic cell death induced by the pro-inflammatory cytokine TNF-α, whereas JWH133 enhanced the cytokine cytotoxicity. Blockade of ERK1/2 and p38 MAPK activation abrogated the HU210 pro-survival and the JWH133 pro-apoptotic effects, respectively. HU210 and the endocannabinoid anandamide, but not JWH133, potentiated ERK1/2 stimulation by LPA and the tricyclic antidepressant amitriptyline acting through the LPA₁ receptor. HU210 enhanced amitriptyline-stimulated CREB phosphorylation and protection against TNF-α-induced apoptosis, whereas JWH133 had no effect. ERK1/2 stimulation by either HU210 or amitriptyline was dependent on fibroblast growth factor receptor (FGF-R) kinase activity and the combination of the two stimulants induced FGF-R phosphorylation. Moreover, the CB₁ receptor was found to co-immunoprecipitate with the LPA₁ receptor.

CONCLUSIONS

In HT22 hippocampal cells CB₁ and CB₂ receptors differentially regulate TNF-α-induced apoptosis and CB₁ receptors positively interact with amitriptyline-stimulated LPA₁ in promoting FGF-R-mediated ERK1/2 signaling and neuroprotection.

GPCR oligomerization as a target for antidepressants: Focus on GPR39

At present most of the evidence for the relevance of oligomerization for the pharmacology of depression comes from in vitro studies which identified oligomers, and from neuropsychopharmacological studies of receptors which participate in oligomerization. For example, behavioural and biochemical studies in knockout animals suggest that GPR39 may mediate the antidepressant action of monoaminergic antidepressants. We have recently found long-lasting antidepressant-like effects of GPR39 agonist, thus suggesting GPR39 as a target for the development of novel antidepressant drugs. In vitro studies have shown that GPR39 oligomerizes with other GPCRs. Oligomerization of GPR39 should thus be considered in relation to the development of new antidepressants targeting this receptor as well as antidepressants targeting other receptors that may form complexes with GPR39. Here, we summarize recent data suggestive of the importance of oligomerization for the pharmacology of depression and discuss approaches for validation of this phenomenon.

Anomalous brain gyrification patterns in major psychiatric disorders: a systematic review and transdiagnostic integration

Anomalous patterns of brain gyrification have been reported in major psychiatric disorders, presumably reflecting their neurodevelopmental pathology. However, previous reports presented conflicting results of patients having hyper-, hypo-, or normal gyrification patterns and lacking in transdiagnostic consideration. In this article, we systematically review previous magnetic resonance imaging studies of brain gyrification in schizophrenia, bipolar disorder, major depressive disorder, and autism spectrum disorder at varying illness stages, highlighting the gyral pattern trajectory for each disorder. Patients with each psychiatric disorder may exhibit deviated primary gyri formation under neurodevelopmental genetic control in their fetal life and infancy, and then exhibit higher-order gyral changes due to mechanical stress from active brain changes (e.g., progressive reduction of gray matter volume and white matter integrity) thereafter, representing diversely altered pattern trajectories from those of healthy controls. Based on the patterns of local connectivity and changes in neurodevelopmental gene expression in major psychiatric disorders, we propose an overarching model that spans the diagnoses to explain how deviated gyral pattern trajectories map onto clinical manifestations (e.g., psychosis, mood dysregulation, and cognitive impairments), focusing on the common and distinct gyral pattern changes across the disorders in addition to their correlations with specific clinical features. This comprehensive understanding of the role of brain gyrification pattern on the pathophysiology may help to optimize the prediction and diagnosis of psychiatric disorders using objective biomarkers, as well as provide a novel nosology informed by neural circuits beyond the current descriptive diagnostics.

Fibroblast Growth Factor 2 Implicated in Childhood Anxiety and Depression Symptoms

BACKGROUND

Research links fibroblast growth factor 2 (FGF2) to anxiety and depression in rodents and human adults. Our study is the first to examine FGF2 levels in a pediatric population.

METHODS

We assayed serum FGF2 in 163 children with a broad range of anxiety and depressive symptoms; 111 were clinic-referred anxious and depressed children; 52 were non-referred children. We examined associations between FGF2 and anxiety and depression symptoms, and between each of the three facets of behavioral activation (Reward-Responsiveness, Drive, Fun-Seeking) and behavioral avoidance. We used confirmatory factor analysis (CFA) to determine the relative contribution of anxiety and depression indicators and of FGF2 to a latent variable of Anxiety/Depression. We also examined stability of FGF2 levels.

RESULTS

FGF2 levels in clinic-referred children were significantly lower compared with non-referred children. Bivariate correlations and CFA showed negative associations between FGF2 and anxiety, depression and behavioral avoidance. FGF2 levels were positively correlated with the Reward-Responsiveness facet of behavioral activation, implicated in depression. FGF2 levels were stable over six months.

LIMITATIONS

We did not have data on behavioral avoidance and stability of FGF2 in the entire sample.

CONCLUSIONS

Our results implicate FGF2 in anxiety and depression in children, providing an important first step in showing FGF2 may serve as a stable biomarker for these prevalent and impairing problems.

Biomarkers of Major Depressive Disorder: Knowing is Half the Battle

Major depressive disorder (MDD) is a heterogeneous disease which is why there are currently no specific methods to accurately test the severity, endophenotype or therapy response. This lack of progress is partly attributed to the com-plexity and variability of depression, in association with analytical variability of clinical literature and the wide number of theoretically complex biomarkers. The literature accessible, indicates that markers involved in inflammatory, neuro-trophic and metabolic processes and components of neurotransmitters and neuroendocrine systems are rather strong indicators to be considered clinically and can be measured through genetic and epigenetic, transcriptomic and proteomic, metabolomics and neuroimaging assessments. Promising biologic systems/markers found were i.e., growth biomarkers, endocrine markers, oxidant stress markers, proteomic and chronic inflammatory markers, are discussed in this review. Several lines of evidence suggest that a portion of MDD is a dopamine agonist-responsive subtype. This review analyzes concise reports on the pathophysiological biomarkers of MDD and therapeutic reactions via peripheral developmental factors, inflammative cytokines, endocrine factors and metabolic markers. Various literatures also support that endocrine and metabolism changes are associated with MDD. Accumulating evidence suggests that at least a portion of MDD patients show characteristics pathological changes regarding different clinical pathological biomarkers. By this review we sum up all the different biomarkers playing an important role in the detection or treatment of the different patients suffering from MDD. The review also gives an overview of different biomarker's playing a potential role in modulating effect of MDD.

Neuronal fibroblast growth factor 22 signaling during development, but not in adults, is involved in anhedonia

Growth factor signaling in the brain is implicated in many neuropsychiatric disorders, including depression, autism, and epilepsy. Fibroblast growth factor 22 is a growth factor that regulates excitatory synapse development and neurogenesis in the brain. We have previously shown that adult mice in which fibroblast growth factor 22 is constitutively inactivated in all cells throughout life (fibroblast growth factor 22-null mice) show anhedonia, a core feature of depression in humans, suggesting that fibroblast growth factor 22 signaling contributes to the regulation of affective behavior. Here we asked (1) whether inactivation of fibroblast growth factor 22 specifically in neurons is sufficient to induce anhedonia in mice and (2) whether fibroblast growth factor 22 signaling is important during development or in adults for the regulation of affective behavior. To address these questions, we performed the sucrose preference test, which is used as an indicator of anhedonia, with neuron-specific conditional fibroblast growth factor 22 knockout mice, in which fibroblast growth factor 22 is inactivated in neurons at birth (neonatal-fibroblast growth factor 22-knockout mice) or in adults (adult-fibroblast growth factor 22-knockout mice). We found that neonatal-fibroblast growth factor 22-knockout mice show anhedonia (decreased preference for sucrose), while adult-fibroblast growth factor 22-knockout mice do not. Therefore, neuronal fibroblast growth factor 22 signaling is critical during development, and not in adults, for the regulation of affective behavior. Our work also implies that defects in growth factor-dependent synapse development, neurogenesis, or both may underlie depression of a developmental origin.