Moderation of adult depression by a polymorphism in the FKBP5 gene and childhood physical abuse in the general population

Targeting FKBP51 prevents stress-induced preterm birth

Preterm birth (PTB) is a leading cause of perinatal morbidity and mortality, with maternal stress-related disorders, such as depression and anxiety, linked to idiopathic PTB (iPTB). At the maternal-fetal interface, decidualized stromal cells (DSCs) exclusively express the progesterone receptor (PR) and play pivotal roles in maintaining pregnancy and initiating labor. DSCs also express FKBP51, a protein that binds to and inhibits transcriptional activity of glucocorticoid and PR receptors and is associated with stress-related diseases. We previously found that iPTB specimens exhibit increased FKBP51 levels and enhanced FKBP51-PR interactions in DSC nuclei. Additionally, we demonstrated that Fkbp5-deficient mice have prolonged gestation and are resistant to stress-induced PTB, suggesting that FKBP51 contributes to iPTB pathogenesis. Since no FDA-approved therapy exists for PTB, we hypothesized that inhibiting FKBP51 could prevent iPTB. Our current results show that the endogenous prostaglandin D2 derivative 15dPGJ2 reduces FKBP51 levels and FKBP51-PR interactions in cultured cells. Maternal stress increases uterine expression of Fkbp5, Oxtr, and Akr1c18, leading to shortened gestation. However, treatment with 15dPGJ2 lowers uterine Fkbp51, Oxtr, and Ptgs2 levels and prevents stress-induced PTB. Notably, co-treatment with 15dPGJ2 and either P4 or R5020 produced the most significant effects, highlighting the potential of 15dPGJ2 alone or in combination with progestins as a promising therapeutic strategy to prevent PTB.

The rs1360780 Variant of FKBP5: Genetic Variation, Epigenetic Regulation, and Behavioral Phenotypes

FKBP5 has been of special scientific interest in the behavioral sciences since it has been involved in the pathophysiology of several mental disorders. It is a gene with pleiotropic effects which encodes the protein FKBP5, a cochaperone that decreases glucocorticoid receptor (GR) affinity for glucocorticoids by competing with FKBP4, altering the GR chaperone complex, and impairing GR activation. As a key modulator of the stress response, FKBP5 plays a critical role in regulating cortisol levels in the organism. The FKBP5 gene is regulated through a combination of transcriptional, epigenetic, post-transcriptional, and environmental mechanisms, as well as genetic polymorphisms that influence its transcription and stress responsiveness. Notably, the rs1360780 T-allele in FKBP5 significantly affects FKBP5 regulation and has been linked to stress-related disorders by influencing transcription and stress responsiveness. In this narrative review, we aim to provide an overview of the role played by the single-nucleotide polymorphism rs1360780 in the FKBP5 locus in gene expression, its epigenetic regulation, and the impact of early stress in its functioning. We discuss some brain regions with differential expression of FKBP5 and some behavioral phenotypes linked to the locus. The T-allele of rs1360780 is considered a risk variant, as it leads to high FKBP5 induction, which delays negative feedback and increases GR resistance. This results in states of relative hypercortisolemia and brain morphofunctional alterations, particularly in regions sensitive to glucocorticoid activity during critical periods of neurodevelopment. Additionally, exposure to childhood maltreatment is associated with demethylation of the glucocorticoid response elements of FKBP5, further increasing its expression levels. Among the psychological dimensions analyzed in which FKBP5 is involved are neurocognition, aggression, suicidality, and social cognition. At the level of mental disorders, the gene may play a role in the pathogenesis of post-traumatic stress disorder, depression, and bipolar disorder. In psychotic disorders, its role is less clear. This knowledge enhances the understanding of disease mechanisms that operate through psychopathological dimensions, and highlights the need to design specific, person-centered psychopharmacological and environmental therapeutic interventions.

Transcriptional evidence of HPA axis dysregulation in adolescent females: Unique contributions of chronic early-life stressor exposure and maternal depression history

BACKGROUND

Depression risk increases dramatically for adolescent females following the pubertal transition. Although chronic early-life stressor exposure and a maternal history of depression are established risk factors for depression onset in this population, we know little about the biological mechanisms underlying these associations.

METHOD

To investigate, we examined how chronic early-life stressor exposure and maternal depression history were associated with stress-related gene expression patterns, using a high-risk family design in 48 psychiatrically healthy adolescent females, 20 of whom had a mother with a lifetime history of depression. Lifetime chronic stressor exposure was assessed using the STRAIN and gene expression patterns were estimated using transcriptional profiling of whole blood.

RESULTS

Consistent with hypotheses, we found that adolescent females with greater chronic stressor exposure had higher NR3C1 expression levels compared to those with less chronic stressor exposure. Additionally, youth with a depressed mother had lower levels of FKBP5 expression compared to those without a depressed mother. Levels of FKBP5 expression, in turn, interacted with chronic stressor exposure to predict NR3C1 expression. Specifically, for those with low chronic stressor exposure, levels of FKBP5 and NR3C1 expression were strongly interrelated, whereas for those with high chronic stressor exposure, NR3C1 expression was high regardless of levels of FKBP5 expression.

LIMITATIONS

This study was correlational, the sample size was limited, and additional research is needed to elucidate the underlying mechanisms and predict who subsequently develops depression.

CONCLUSIONS

Notwithstanding these limitations, these data indicate that having low FKBP5 expression, alongside high NR3C1 expression, may be a potential preclinical marker of depression risk in adolescent females that warrants additional investigation.

Genetically engineered mouse models of FK506-binding protein 5

FK506 binding protein 51 (FKBP51) is a molecular chaperone that influences stress response. In addition to having an integral role in the regulation of steroid hormone receptors, including glucocorticoid receptor, FKBP51 has been linked with several biological processes including metabolism and neuronal health. Genetic and epigenetic alterations in the gene that encodes FKBP51, FKBP5, are associated with increased susceptibility to multiple neuropsychiatric disorders, which has fueled much of the research on this protein. Because of the complexity of these processes, animal models have been important in understanding the role of FKBP51. This review examines each of the current mouse models of FKBP5, which include whole animal knockout, conditional knockout, overexpression, and humanized mouse models. The generation of each model and observational details are discussed, including behavioral phenotypes, molecular changes, and electrophysiological alterations basally and following various challenges. While much has been learned through these models, there are still many aspects of FKBP51 biology that remain opaque and future studies are needed to help illuminate these current gaps in knowledge. Overall, FKBP5 continues to be an exciting potential target for stress-related disorders.

Early life adversities, psychopathologies and novel pharmacological strategies

Exposure to adversities during early life stages (early life adversities - ELA), ranging from pregnancy to adolescence, represents a major risk factor for the vulnerability to mental disorders. Hence, it is important to understand the molecular and functional underpinning of such relationship, in order to develop strategies aimed at reducing the psychopathologic burden associated with ELA, which may eventually lead to a significant improvement in clinical practice. In this review, we will initially recapitulate clinical and preclinical evidence supporting the link between ELA and psychopathology and we will primarily discuss the main biological mechanisms that have been described as potential mediators of the effects of ELA on the psychopathologic risk, including the role for genetic factors as well as sex differences. The knowledge emerging from these studies may be instrumental for the development of novel therapeutic strategies aimed not only at correcting the deficits that emerge from ELA exposure, but also in preventing the manifestation of a full-blown psychopathologic condition. With this respect, we will specifically focus on adolescence as a key time frame for disease onset as well as for early therapeutic intervention. We believe that incorporating clinical and preclinical research data in the context of early life adversities can be instrumental to elucidate the mechanisms contributing to the risk for psychopathology or that may promote resilience. This will ultimately allow the identification of 'at risk' individuals who may benefit from specific forms of interventions that, by interfering with disease trajectories, could result in more benign clinical outcomes.

Polygenic risk, childhood abuse and gene x environment interactions with depression development from middle to late adulthood: A U.S. national life-course study

OBJECTIVE

Utilizing national longitudinal data, this study examines how polygenic depression risk and childhood abuse interactively influence the life-course development of depressive conditions from middle to late adulthood.

METHOD

Data from 7512 participants (4323 females and 3189 males) of European ancestry aged 51-90, retrieved from the U.S. Health and Retirement Study (1992-2020), were analyzed. Childhood physical abuse and polygenic depression score were the primary predictors. Depressive symptoms were assessed using the Center for Epidemiologic Studies-Depression (CESD) scale, and clinical depression risk was a binary indicator. Growth-curve linear mixed and logit mixed-effects models were conducted for analysis.

RESULTS

Increasing polygenic depression scores were associated with elevated CES-D levels and potential risks of clinical depression. Males experienced more detrimental effects of childhood abuse on depression development from ages 51 to 90 years. In contract, non-maltreated females generally exhibited higher depressive symptoms and clinical depression risk than males. A significant interactive effect was found between polygenic depression risk and childhood abuse among males. Higher depression levels and clinical risk were observed with increasing polygenic depression score among maltreated males, surpassing those of females with standardized polygenic score ≥0 from age 51 to 90 years.

CONCLUSIONS

The interaction between childhood abuse and genetic factors significantly shaped lifelong depression trajectories in males, while the negative impact of abusive parenting remained constant regardless of polygenic depression risk among females. Individualized prevention and intervention strategies could be crucial in mitigating lifelong depression development, especially for high-genetic-risk males with a history of childhood physical abuse.

Differentially expressed heterogeneous overdispersion genes testing for count data

The mRNA-seq data analysis is a powerful technology for inferring information from biological systems of interest. Specifically, the sequenced RNA fragments are aligned with genomic reference sequences, and we count the number of sequence fragments corresponding to each gene for each condition. A gene is identified as differentially expressed (DE) if the difference in its count numbers between conditions is statistically significant. Several statistical analysis methods have been developed to detect DE genes based on RNA-seq data. However, the existing methods could suffer decreasing power to identify DE genes arising from overdispersion and limited sample size, where overdispersion refers to the empirical phenomenon that the variance of read counts is larger than the mean of read counts. We propose a new differential expression analysis procedure: heterogeneous overdispersion genes testing (DEHOGT) based on heterogeneous overdispersion modeling and a post-hoc inference procedure. DEHOGT integrates sample information from all conditions and provides a more flexible and adaptive overdispersion modeling for the RNA-seq read count. DEHOGT adopts a gene-wise estimation scheme to enhance the detection power of differentially expressed genes when the number of replicates is limited as long as the number of conditions is large. DEHOGT is tested on the synthetic RNA-seq read count data and outperforms two popular existing methods, DESeq2 and EdgeR, in detecting DE genes. We apply the proposed method to a test dataset using RNAseq data from microglial cells. DEHOGT tends to detect more differently expressed genes potentially related to microglial cells under different stress hormones treatments.

Interaction of childhood trauma with BDNF and FKBP5 gene polymorphisms in predicting burnout in general occupational groups

Both the BDNF gene rs6265 and the FKBP5 gene rs1360780 polymorphisms are independently associated with adult psychotic-like experiences, when exposed to high childhood abuse; however, it remains unclear whether the relationship between childhood abuse and burnout is moderated by these two single nucleotide polymorphisms (SNPs). Furthermore, there is an interaction between glucocorticoid receptor transcriptional activity and BDNF signaling. Therefore, we investigated the interaction of these two SNPs with childhood trauma in predicting burnout. We recruited 990 participants (mean age 33.06 years, S.D. = 6.31) from general occupational groups and genotyped them for rs6265 and rs1360780. Burnout, childhood trauma, resilience, and job stress were measured through a series of rating scales. Gene-by-environment and gene-by-gene-by-environment interactions were examined using linear hierarchical regression and PROCESS macro in SPSS. Covariates included demographics and resilience. We found that rs6265 moderated the association between job stress and emotional exhaustion. Both rs6265 and rs1360780 moderated the association between childhood abuse and cynicism. There was significant interaction of childhood abuse × rs6265 × rs1360780 on emotional exhaustion and reduced personal accomplishment, so that rs6265 CC genotype and rs1360780 TT genotype together predicted higher levels of emotional exhaustion under high childhood abuse, while rs6265 TT genotype and rs1360780 CC genotype together exerted a resilient effect on reduced personal accomplishment in the face of childhood abuse. Our findings suggest that the rs6265 CC genotype and rs1360780 TT genotype may jointly contribute to increased risk of burnout under childhood trauma.

The Role of FKBPs in Complex Disorders: Neuropsychiatric Diseases, Cancer, and Type 2 Diabetes Mellitus

Stress is a common denominator of complex disorders and the FK-506 binding protein (FKBP)51 plays a central role in stress. Hence, it is not surprising that multiple studies imply the involvement of the FKBP51 protein and/or its coding gene, FKBP5, in complex disorders. This review summarizes such reports concentrating on three disorder clusters-neuropsychiatric, cancer, and type 2 diabetes mellitus (T2DM). We also attempt to point to potential mechanisms suggested to mediate the effect of FKBP5/FKBP51 on these disorders. Neuropsychiatric diseases considered in this paper include (i) Huntington's disease for which increased autophagic cellular clearance mechanisms related to decreased FKBP51 protein levels or activity is discussed, Alzheimer's disease for which increased FKBP51 activity has been shown to induce Tau phosphorylation and aggregation, and Parkinson's disease in the context of which FKBP12 is mentioned; and (ii) mental disorders, for which significant association with the single nucleotide polymorphism (SNP) rs1360780 of FKBP5 intron 7 along with decreased DNA methylation were revealed. Since cancer is a large group of diseases that can start in almost any organ or tissue of the body, FKBP51's role depends on the tissue type and differences among pathways expressed in those tumors. The FKBP51-heat-shock protein-(Hsp)90-p23 super-chaperone complex might function as an oncogene or as a tumor suppressor by downregulating the serine/threonine protein kinase (AKt) pathway. In T2DM, two potential pathways for the involvement of FKBP51 are highlighted as affecting the pathogenesis of the disease-the peroxisome proliferator-activated receptor-γ (PPARγ) and AKt.

Methylation Patterns of the FKBP5 Gene in Association with Childhood Maltreatment and Depressive Disorders

Childhood maltreatment is an important risk factor for adult depression and has been associated with changes in the hypothalamic pituitary adrenal (HPA) axis, including cortisol secretion and methylation of the FKBP5 gene. Furthermore, associations between depression and HPA changes have been reported. This study investigated the associations of whole-blood FKBP5 mRNA levels, serum cortisol levels, childhood maltreatment, and depressive symptoms with the whole-blood methylation status (assessed via target bisulfite sequencing) of 105 CpGs at the FKBP5 locus using data from the general population-based Study of Health in Pomerania (SHIP) (N = 203). Both direct and interaction effects with the rs1360780 single-nucleotide polymorphism were investigated. Nominally significant associations of main effects on methylation of a single CpG site were observed at intron 3, intron 7, and the 3'-end of the gene. Additionally, methylation at two clusters at the 3'-end and intron 7 were nominally associated with childhood maltreatment × rs1360780 and depressive symptoms × rs1360780, respectively. The results add to the understanding of molecular mechanisms underlying the emergence of depression and could aid the development of personalised depression therapy and drug development.

Sex Differences in the Neurobiology of Stress

This review highlights the existing knowledge and data that explain the physiologic impacts of stress, especially pertaining to neurobiology, and how these impacts differ by sex. Furthermore, this review explains the benefits of interventions aimed at preventing or mitigating the adverse effects of stress, because of both the significant toll of stress on the body and the disproportionate impact of these changes experienced by women.

Child DNA methylation in a randomised controlled trial of a video-feedback intervention to promote positive parenting and sensitive discipline (VIPP-SD)

Introduction

A major modifiable risk factor for behavioural difficulties is harsh and insensitive parenting, and it has been hypothesised that the biological mechanism by which parenting influences child behaviour is via changes in the child's DNA methylation. We attempted to, in part, address the hypothesis that parenting is associated with child DNA methylation and, in turn, behaviour.

Methods

Primary caregivers of young children with behavioural difficulties (children aged 12-36 months) were randomised to receive a video-feedback Intervention to promote Positive Parenting and Sensitive Discipline (VIPP-SD) (n = 151), or usual care (n = 149). Child buccal samples were collected at a 2-year post-randomisation follow up (children aged 3-5 years, VIPP-SD group n = 106, usual care group n = 117) and were assessed for DNA methylation at the NR3C1, FKBP5 and OXYR genes. Child behaviour was assessed at baseline, post-intervention and 2-years post-randomisation using the Preschool Parental Account of Children's Symptoms (PPACS). We examined group differences in DNA methylation, associations of DNA methylation with behaviour, and sex differences.

Results

For the NR3C1 and OXYR genes, there were no group differences, sex differences, or associations of DNA methylation with child behaviour, though all non-significant findings were in the hypothesised direction. For FKBP5 DNA methylation, there was a significant interaction between group and sex, such that males in the usual care group had higher DNA methylation than females, but in the intervention group females had higher DNA methylation than males. However, FKBP5 DNA methylation was not associated with behaviour in males or females.

Discussion

We provide the first evidence from a randomised controlled trial focused on improving parenting for sex-specific changes in child DNA methylation at a key gene involved in stress reactivity and psychopathology. This study adds to our understanding of causal mechanisms linking parenting with child behaviour, which is important for developing targeted interventions. A key limitation is that child DNA methylation was only assessed at one time point, so we were unable to assess change in DNA methylation over time. However, we demonstrate that is possible to collect and analyse DNA samples from families with young children receiving parenting interventions in the community, providing impetus for further research on this topic.

Differentially Expressed Heterogeneous Overdispersion Genes Testing for Count Data

The mRNA-seq data analysis is a powerful technology for inferring information from biological systems of interest. Specifically, the sequenced RNA fragments are aligned with genomic reference sequences, and we count the number of sequence fragments corresponding to each gene for each condition. A gene is identified as differentially expressed (DE) if the difference in its count numbers between conditions is statistically significant. Several statistical analysis methods have been developed to detect DE genes based on RNA-seq data. However, the existing methods could suffer decreasing power to identify DE genes arising from overdispersion and limited sample size. We propose a new differential expression analysis procedure: heterogeneous overdispersion genes testing (DEHOGT) based on heterogeneous overdispersion modeling and a post-hoc inference procedure. DEHOGT integrates sample information from all conditions and provides a more flexible and adaptive overdispersion modeling for the RNA-seq read count. DEHOGT adopts a gene-wise estimation scheme to enhance the detection power of differentially expressed genes. DEHOGT is tested on the synthetic RNA-seq read count data and outperforms two popular existing methods, DESeq and EdgeR, in detecting DE genes. We apply the proposed method to a test dataset using RNAseq data from microglial cells. DEHOGT tends to detect more differently expressed genes potentially related to microglial cells under different stress hormones treatments.

The Role of Genetics in the Development and Pharmacotherapy of Depression and Its Impact on Drug Discovery

Complex disorders, such as depression, remain a mystery for scientists. Although genetic factors are considered important for the prediction of one's vulnerability, it is hard to estimate the exact risk for a patient to develop depression, based only on one category of vulnerability criteria. Genetic factors also regulate drug metabolism, and when they are identified in a specific combination, may result in increased drug resistance. A proper understanding of the genetic basis of depression assists in the development of novel promising medications and effective disorder management schemes. This review aims to analyze the recent literature focusing on the correlation between specific genes and the occurrence of depression. Moreover, certain aspects targeting a high drug resistance identified among patients suffering from major depressive disorder were highlighted in this manuscript. An expected direction of future drug discovery campaigns was also discussed.

The body keeps the score: The neurobiological profile of traumatized adolescents

Trauma-related disorders are debilitating psychiatric conditions that affect people who have directly or indirectly witnessed adversities. Experiencing multiple types of traumas appears to be common during childhood, and even more so during adolescence. Dramatic brain/body transformations occurring during adolescence may provide a highly responsive substrate to external stimuli and lead to trauma-related vulnerability conditions, such as internalizing (anxiety, depression, anhedonia, withdrawal) and externalizing (aggression, delinquency, conduct disorders) problems. Analyzing relations among neuronal, endocrine, immune, and biochemical signatures of trauma and internalizing and externalizing behaviors, including the role of personality traits in shaping these conducts, this review highlights that the marked effects of traumatic experience on the brain/body involve changes at nearly every level of analysis, from brain structure, function and connectivity to endocrine and immune systems, from gene expression (including in the gut) to the development of personality.

Epidemiology of Childhood Trauma and Analysis of Influencing Factors in Psychiatric Disorders Among Chinese Adolescents: A Cross-sectional Study

Childhood trauma (CT) can lead to long-term psychiatric disturbances. The current study investigated the prevalence of CT and its associated risk factors among Chinese adolescents with psychiatric disorders. Adolescents were recruited from a large study on mental health in the Hunan province of China in 2014. The study had a two-phase cross-sectional design. Patients with mental disorders (n = 907) and healthy subjects (n = 2,240) completed the Childhood Trauma Questionnaire-Short Form. Of all types of CT, emotional neglect (EN; 48.44%-68.82%) and physical neglect (PN; 60.0%-72.1%) were most common among adolescents. The experience of emotional abuse (EA), physical abuse (PA), sexual abuse (SA), EN, and multiple types of trauma (≥3) was higher among adolescents with psychiatric disorders than the healthy comparison group. Moreover, the results of logistic regression analysis showed that living in semi-urban areas and villages, having a sibling, and having bad-to-average academic performance were risk factors for CT among adolescents with psychiatric disorders (p < .05). In additional, the results of logistic regression analysis revealed that being a left-behind child and bad academic performance were risk factors for experiencing multiple types (≥3) of CT (p < .05), while being female and having siblings were found to be protective factors against (≥3) CT (p < .05). In summary, the prevalence rate of CT (especially multiple types of trauma) is high among adolescents with psychiatric disorders. These results indicate the importance of reducing CT to limit the likelihood of psychiatric disorders, especially among adolescents.

Cross-tissue analysis of blood and brain epigenome-wide association studies in Alzheimer's disease

To better understand DNA methylation in Alzheimer's disease (AD) from both mechanistic and biomarker perspectives, we performed an epigenome-wide meta-analysis of blood DNA methylation in two large independent blood-based studies in AD, the ADNI and AIBL studies, and identified 5 CpGs, mapped to the SPIDR, CDH6 genes, and intergenic regions, that are significantly associated with AD diagnosis. A cross-tissue analysis that combined these blood DNA methylation datasets with four brain methylation datasets prioritized 97 CpGs and 10 genomic regions that are significantly associated with both AD neuropathology and AD diagnosis. An out-of-sample validation using the AddNeuroMed dataset showed the best performing logistic regression model includes age, sex, immune cell type proportions, and methylation risk score based on prioritized CpGs in cross-tissue analysis (AUC = 0.696, 95% CI: 0.616 - 0.770, P-value = 2.78 × 10^-5). Our study offers new insights into epigenetics in AD and provides a valuable resource for future AD biomarker discovery.

Going beyond risk factor: Childhood maltreatment and associated modifiable targets to improve life-long outcomes in mood disorders

Childhood maltreatment increases risk for mood disorders and is associated with earlier onset-and more pernicious disease course following onset-of mood disorders. While the majority of studies to date have been cross-sectional, longitudinal studies are emerging and support the devastating role(s) childhood maltreatment has on development of, and illness course in, mood disorders. This manuscript extends prior reviews to emphasize more recent work, highlighting longitudinal data, and discusses treatment studies that provide clues to mechanisms that mediate disease risk, course, relapse, and treatment response. Evidence suggesting systemic inflammation, alterations in hypothalamic-pituitary-adrenal (HPA) axis function and corticotropin-releasing factor (CRF) neural systems, genetic and other familial factors as mechanisms that mediate risk and onset of, and illness course in, mood disorders following childhood maltreatment is discussed. Risky behaviors following maltreatment, e.g., substance use and unhealthy lifestyles, may further exacerbate alterations in the HPA axis, CRF neural systems, and systematic inflammation to contribute to a more pernicious disease course. More research on sex differences and the impact of maltreatment in vulnerable populations is needed. Future research needs to be aimed at leveraging knowledge on modifiable targets, going beyond childhood maltreatment as a risk factor, to inform prevention and treatment strategies and foster trauma-informed care.

Early adversity as the prototype gene × environment interaction in mental disorders?

Childhood adversity (CA) as a significant stressor has consistently been associated with the development of mental disorders. The interaction between CA and genetic variants has been proposed to play a substantial role in disease etiology. In this review, we focus on the gene by environment (GxE) paradigm, its background and interpretation and stress the necessity of its implementation in psychiatric research. Further, we discuss the findings supporting GxCA interactions, ranging from candidate gene studies to polygenic and genome-wide approaches, their strengths and limitations. To illustrate potential underlying epigenetic mechanisms by which GxE effects are translated, we focus on results from FKBP5 × CA studies and discuss how molecular evidence can supplement previous GxE findings. In conclusion, while GxE studies constitute a valuable line of investigation, more harmonized GxE studies in large, deep-phenotyped, longitudinal cohorts, and across different developmental stages are necessary to further substantiate and understand reported GxE findings.

Regulatory functions of FKBP5 intronic regions associated with psychiatric disorders

The FKBP5 gene codifies a co-chaperone protein associated with the modulation of glucocorticoid receptor interaction involved in the adaptive stress response. The FKBP5 intracellular concentration affects the binding affinity of the glucocorticoid receptor (GR) to glucocorticoids (GCs). This gene has glucocorticoid response elements (GREs) located in introns 2, 5 and 7, which affect its expression. Recent studies have examined GRE activity and the effects of genetic variants on transcript efficiency and their contribution to susceptibility to behavioral disorders. Epigenetic changes and environmental factors can influence the effects of these allele-specific variants, impacting the response to GCs of the FKBP5 gene. The main epigenetic mark investigated in FKBP5 intronic regions is DNA methylation, however, few studies have been performed for all GREs located in these regions. One of the major findings was the association of low DNA methylation levels in the intron 7 of FKBP5 in patients with psychiatric disorders. To date, there are no reports of DNA methylation in introns 2 and 5 of the gene associated with diagnoses of psychiatric disorders. This review highlights what has been discovered so far about the relationship between polymorphisms and epigenetic targets in intragenic regions, and reveals the gaps that need to be explored, mainly concerning the role of DNA methylation in these regions and how it acts in psychiatric disease susceptibility.

FKBP5 and early life stress affect the hippocampus by an age-dependent mechanism

Early life stress (ELS) adversely affects the brain and is commonly associated with the etiology of mental health disorders, like depression. In addition to the mood-related symptoms, patients with depression show dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, increased peripheral inflammation, and structural brain alterations. Although the underlying causes are unknown, polymorphisms in the FK506-binding protein 5 (FKBP5) gene, a regulator of glucocorticoid receptor (GR) activity, interact with childhood adversities to increase vulnerability to depressive disorders. We hypothesized that high FKBP5 protein levels combined with early life stress (ELS) would alter the HPA axis and brain, promoting depressive-like behaviors. To test this, we exposed males and females of a mouse model overexpressing FKBP5 in the brain (rTgFKBP5 mice), or littermate controls, to maternal separation for 14 days after birth. Then, we evaluated neuroendocrine, behavioral, and brain changes in young adult and aged mice. We observed lower basal corticosterone (CORT) levels in rTgFKBP5 mice, which was exacerbated in females. Aged, but not young, rTgFKBP5 mice showed increased depressive-like behaviors. Moreover, FKBP5 overexpression reduced hippocampal neuron density in aged mice, while promoting markers of microglia expression, but these effects were reversed by ELS. Together, these results demonstrate that high FKBP5 affects basal CORT levels, depressive-like symptoms, and numbers of neurons and microglia in the hippocampus in an age-dependent manner.

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High FKBP5 reduces basal corticosterone levels in mice, especially in females.

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ELS prevents FKBP5-induced susceptibility to depressive-like behavior in aged mice.

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FKBP5 overexpression reduces hippocampal neuron density in aged mice, while increasing microglial markers.

Association of FKBP5 gene variants with depression susceptibility: A comprehensive meta-analysis

BACKGROUND

This comprehensive meta-analysis aimed to combine data from different studies and to estimate the association between FKBP5 polymorphisms and depression.

METHODS

We performed a meta-analysis of observational studies. An electronic search was conducted on four databases for articles published before July 1, 2020.

RESULTS

A total of 5125 patients with depression and 8399 controls from 16 independent studies were included in the analysis. The results showed that FKBP5 rs1360780 was associated with the risk of depression in the codominant model (CT vs. CC; OR = 1.10, 95% CI = 1.00-1.20, P = .04); rs4713916 polymorphism was associated with depression in the codominant model (AG vs. GG; OR = 1.19, 95% CI = 1.05-1.34, P = .008) and recessive model (AA vs. AG + GG; OR = 0.74, 95% CI = 0.56-0.99, P = .04); a significant association between rs3800373 and depression was found in the codominant genetic model (AC vs. AA; OR = 1.18, 95% CI = 1.05-1.34, P = .007) and dominant model (CC + AC vs. AA; OR = 1.15, 95% CI = 1.03-1.30, P = .02); there was no significant association of FKBP5 rs9470080 or rs9296158 with depression in any genetic model (P > .05). No publication bias was observed in our analysis. Moreover, sensitivity analyses demonstrated the Zobel's study significantly affected the heterogeneity for rs4713916 and rs3800373.

CONCLUSIONS

FKBP5 rs1360780 was associated with an increased risk of depression in the codominant model. We also found that rs4713916 and rs3800373 were involved in depression, rs4713916 was positively associated with depression in the codominant model and recessive model, and rs3800373 was related to an elevated risk of depression in the codominant model and dominant model.

HPA-axis multilocus genetic profile score moderates the association between maternal prenatal perceived stress and offspring depression in early adulthood

Maternal stress during pregnancy can cause alterations to the fetal hypothalamus-pituitary-adrenal (HPA) axis, a phenomenon known as fetal programming that may have lasting effects on offspring outcomes, including depression. Evidence suggests that these effects may vary with respect to the offspring's genetic risk. Nonetheless, few studies have examined these effects into adulthood, when risk for depression onset is highest. The present study builds upon the extant literature by examining the interaction of maternal prenatal perceived stress (MPPS) and offspring HPA-axis polygenic risk to predict offspring depression in early adulthood. A total of 381 mother-child dyads participated in a prospective, longitudinal study that spanned from pregnancy until offspring were 20 years of age. Polygenic risk was defined by a multilocus genetic profile score (MGPS) that reflected the additive risk of three HPA-axis candidate genes. The results indicated that the interaction of MPPS and HPA-axis MGPS confers risk for offspring depression at age 20, in line with the differential susceptibility model. This interaction may be specific to prenatal stress, as maternal stress during early childhood did not interact with genetic risk to predict depression. These findings provide the first evidence that genetic variants that are associated with the HPA axis may act in a polygenic, additive fashion to moderate the association between fetal programming and adult depression.

Can Molecular Biology Propose Reliable Biomarkers for Diagnosing Major Depression?

BACKGROUND

Modern medicine has provided considerable knowledge of the pathophysiology of mental disorders at the body, systemic, organ and neurochemical levels of the biological organization of the body. Modern clinical diagnostics of depression have some problems, that is why psychiatric society makes use of diagnostics and taxonomy of different types of depression by implemention of modern molecular biomarkers in diagnostic procedures. But up to now, there are no reliable biomarkers of major depressive disorder (MDD) and other types of depression.

OBJECTIVE

The purpose of this review is to find fundamentals in pathological mechanisms of depression, which could be a basis for development of molecular and genetic biomarkers, being the most feasible for clinical use.

METHOD

This review summarizes the published data using PubMed, Science Direct, Google Scholar and Scopus.

RESULTS

In this review, we summarized and discussed findings in molecular biology, genetics, neuroplasticity, neurotransmitters, and neuroimaging that could increase our understanding of the biological foundations of depression and show new directions for the development of reliable biomarkers. We did not find any molecular and genetic biomarker approved for the clinic. But the Genome-Wide Association Study method promises some progress in the development of biomarkers based on SNP in the future. Epigenetic factors also are a promising target for biomarkers. We have found some differences in the etiology of different types of atypical and melancholic depression. This knowledge could be the basis for development of biomarkers for clinical practice in diagnosis, prognosis and selection of treatment.

CONCLUSION

Depression is not a monoetiological disease. Many pathological mechanisms are involved in depression, thus up to now, there is no approved and reliable biomarker for diagnosis, prognosis and correction of treatment of depression. The structural and functional complexity of the brain, the lack of invasive technology, poor correlations between genetic and clinical manifestation of depression, imperfect psychiatric classification and taxonomy of subtypes of disease are the main causes of this situation. One of the possible ways to come over this situation can be to pay attention to the trigger mechanism of disease and its subtypes. Researchers and clinicians should focus their efforts on searching the trigger mechanism of depression and different types of it . HPA axis can be a candidate for such trigger in depression caused by stress, because it influences the main branches of disease: neuroinflammation, activity of biogenic amines, oxidative and nitrosative stress, epigenetic factors, metabolomics, etc. But before we shall find any trigger mechanism, we need to create complex biomarkers reflecting genetic, epigenetic, metabolomics and other pathological changes in different types of depression. Recently the most encouraging results have been obtained from genetics and neuroimaging. Continuing research in these areas should be forced by using computational, statistical and systems biology approaches, which can allow to obtain more knowledge about the neurobiology of depression. In order to obtain clinically useful tests, search for biomarkers should use appropriate research methodologies with increasing samples and identifying more homogeneous groups of depressed patients.

Childhood maltreatment and lung function: findings from the general population

OBJECTIVE

Cumulative evidence indicates that childhood maltreatment is linked to self-reported asthma and COPD. However, the relationship between childhood maltreatment and objective measures of lung function as determined by spirometry has not yet been assessed.

METHODS

Medical histories and spirometric lung function were taken in 1386 adults from the general population. Participants completed the Childhood Trauma Questionnaire for the assessment of emotional, physical and sexual abuse as well as emotional and physical neglect.

RESULTS

25.3% of the participants reported at least one type of childhood maltreatment. Among them, use of medication for obstructive airway diseases as well as typical signs and symptoms of airflow limitation were significantly more frequent than in the group without exposure to childhood maltreatment. Although participants with childhood maltreatment had numerically lower values for forced expiratory volume in 1 s (FEV₁), forced vital capacity (FVC) and peak expiratory flow than those without, these differences were nonsignificant when accounting for relevant covariates such as age, sex, height and smoking. Likewise, there were no differences in the FEV₁/FVC ratio nor in the frequency of airflow limitation regardless of its definition. No specific type of childhood maltreatment was related to spirometrically determined parameters of lung function.

CONCLUSIONS

Our findings call into question the association of childhood maltreatment with obstructive lung diseases as indicated by prior research relying on self-reported diagnoses. We consider several explanations for these discrepancies.

Ahi1 regulates the nuclear translocation of glucocorticoid receptor to modulate stress response

Stress activates the nuclear translocation of glucocorticoid receptors (GR) to trigger gene expression. Abnormal GR levels can alter the stress responses in animals and therapeutic effects of antidepressants. Here, we reported that stress-mediated nuclear translocation of GR reduced Ahi1 in the stressed cells and mouse brains. Ahi1 interacts with GR to stabilize each other in the cytoplasm. Importantly, Ahi1 deficiency promotes the degradation of GR in the cytoplasm and reduced the nuclear translocation of GR in response to stress. Genetic depletion of Ahi1 in mice caused hyposensitivity to antidepressants under the stress condition. These findings suggest that AHI1 is an important regulator of GR level and may serve as a therapeutic target for stress-related disorders.

Biological correlates of early life stressful events in major depressive disorder

Major depressive disorder (MDD) is the most common psychiatric disorder and responds for important psychosocial consequences. Stressful life events, especially early life stress (ELS), contribute to an increased probability to develop MDD, leading in particular to severe and chronic manifestation and unfavorable treatment outcome. The association between ELS and MDD seems to have biological bases, consisting in dysregulations occurring at different levels. The aim of this narrative review is to propose an overview of the literature ranging from genetic, epigenetic, expression and protein to neuroimaging correlates underlying this relationship. A search on Pubmed of studies assessing biological correlates of ELS in MDD development, focusing on human studies conducted in both peripheral and brain tissues, was performed. Evidence indicated that the hypothalamic-pituitary-adrenal (HPA) axis and the serotonergic, dopaminergic, neurotrophin and oxytocin systems might play a role in the mediation between ELS and MDD. The most consistent results were found for genetic and epigenetic studies and indicated a joint involvement of the systems mentioned. Expression studies are less numerous and point to an involvement of stress-related systems. Concerning protein studies, the main mediators are markers related to the inflammatory and immune systems. Neuroimaging studies aiming at evaluating brain alterations connecting ELS and MDD in relation to biomarkers indicated the hippocampus, the amygdala and the frontal cortex as important anatomical mediators. These findings can build the bases for future research and clinical interventions; indeed, the clarification of biological mechanisms mediating the relationship between ELS and MDD can lead to new and individualized preventive and therapeutic possibilities.

Similarities and Differences of Mental Health in Women and Men: A Systematic Review of Findings in Three Large German Cohorts

In Germany, large, population-based cohort studies have been implemented in order to identify risk and protective factors for maintaining health across the life span. The purpose of this systematic review is to analyse findings from three large ongoing cohorts and to identify sex-specific prevalence rates, risk and protective factors for mental health. Published studies from the Cooperative Health Research in the Region Augsburg (KORA), the Study of Health in Pomerania (SHIP) and the Gutenberg Health Study (GHS)), representing the southern, north-eastern and middle parts of Germany, were identified through searches of the databases PubMed and Web of Science. A total of 52 articles was identified from the start of each cohort until June 2019. Articles reporting prevalence rates of mental health [N = 22], explanatory factors for mental health [N = 25], or both [N = 5] were identified. Consistent across cohorts, higher prevalence rates of internalizing disorders were found for women and more externalizing disorders for men. Risk and protective factors for mental health included social factors, lifestyle, physical health, body mass index (BMI), diabetes, genetic and biological factors. In all areas, differences and similarities were found between women and men. The most evident were the sex-specific risk profiles for depression with mostly external risk factors for men and internal risk factors for women. Gender was not assessed directly, therefore we examined whether socioeconomic and family-related factors reflecting gender roles or institutionalized gender could be used as a proxy for gender. Overall, this systematic review shows differences and similarities in prevalence rates and determinants of mental health indicators between women and men. They underline the importance of focussing on sex specific approaches in mental health research and in the development of prevention measures. Current research on mental health still lacks focus on gender aspects. Therefore, an increased focus on sex and gender in mental health research is of great importance.

Hypothalamic stress systems in mood disorders

Stress system dysfunction is a typical characteristic of acute depression and other mood disorders. The exact pattern of factors predisposing for stress-related mental disorders is yet to be unraveled. However, corticosteroid receptor function plays an important role for appropriate or dysfunctional neuroendocrine responses to stress exposure and hence in resilience or risk for the development and course of both, depression and anxiety disorders. Solid neuroscience data strongly support that both neuropeptides, corticotropin-releasing hormone (CRH) and vasopressin (AVP), are central in coordinating humoral and behavioral adaptation to stress. Other neuropeptides, including oxytocin, neuropeptide S, neuropeptide Y, and orexin, are also considered important contributors. Attempts to turn neuropeptide biology into treatments for stress-related disorders need to consider that neuropeptide receptors are specific drug targets for certain patient populations rather than universal targets for all patients, like biogenic amine systems. That is why most negative clinical trials testing neuropeptide receptor antagonists have been in fact failed trials by design, because no companion tests were used to identify which patients with depression are most likely to benefit from a specific neuropeptide receptor-targeting drug treatment. Therefore, the most important future research task is discovery and development of appropriate companion tests that will allow the successful transfer of the precious treasure of neuropeptide system-targeting drugs into clinics.

A gene expression atlas for different kinds of stress in the mouse brain

Stressful experiences are part of everyday life and animals have evolved physiological and behavioral responses aimed at coping with stress and maintaining homeostasis. However, repeated or intense stress can induce maladaptive reactions leading to behavioral disorders. Adaptations in the brain, mediated by changes in gene expression, have a crucial role in the stress response. Recent years have seen a tremendous increase in studies on the transcriptional effects of stress. The input raw data are freely available from public repositories and represent a wealth of information for further global and integrative retrospective analyses. We downloaded from the Sequence Read Archive 751 samples (SRA-experiments), from 18 independent BioProjects studying the effects of different stressors on the brain transcriptome in mice. We performed a massive bioinformatics re-analysis applying a single, standardized pipeline for computing differential gene expression. This data mining allowed the identification of novel candidate stress-related genes and specific signatures associated with different stress conditions. The large amount of computational results produced was systematized in the interactive “Stress Mice Portal”.

Interactions of childhood maltreatment and genetic variations in adult depression: A systematic review

Background Childhood maltreatment (CM) significantly increases the risk of adulthood psychopathology. Interplay between susceptible genetic variations and CM contributes to the occurrence of depression. This review aims to systematically synthesize the relationships between genetic variations and depression among those exposed to CM. Methods Electronic databases and gray literature to March 31st, 2020 were searched for literature on the topic of depression and CM limited to English-language. Data extraction and quality assessment of key study characteristics were conducted. Qualitative approaches were used to synthesize the findings. Results The initial search resulted in 9185 articles. A total of 29 articles that met the eligibility criteria were included in this review. High heterogeneity was identified regarding the study sample ages, candidate genes and SNPs, the categorization of CM and depression. The findings of this review include several frequently studied genes (5-HTTLPR, CRHR1, BDNF, CREB1, FKBP5, IL1B, NTRK2, and OXTR). Both consistent and inconsistent findings were identified. Overall, the interplay of CM with CREB1-rs2253206 significantly increased the risk of depression. In contrast, CRHR1-TCA haplotype (rs7209436, rs4792887, rs110402), CRHR1-rs17689882, and CRHR1-rs110402 showed protective effects on depression and depressive symptoms among individuals with a history of maltreatment. Limitations Due to clinical and methodological diversity of the studies a qualitative approach was used. Conclusion This review firstly provides a comprehensive overview of the interplay between CM and genetic variations in adult depression. Future etiological explorations should focus on the above-identified genes for down-stream exploration and address the issues and challenges of gene by environment studies.

FKBP5 polymorphisms induce differential glucocorticoid responsiveness in primary CNS cells - First insights from novel humanized mice

The brain is a central hub for integration of internal and external conditions and, thus, a regulator of the stress response. Glucocorticoids are the essential communicators of this response. Aberrations in glucocorticoid signaling are a common symptom in patients with psychiatric disorders. The gene FKBP5 encodes a chaperone protein that functionally inhibits glucocorticoid signaling and, thus, contributes to the regulation of stress. In the context of childhood trauma, differential expression of FKBP5 has been found in psychiatric patients compared to controls. These variations in expression levels of FKBP5 were reported to be associated with differences in stress responsiveness in human carriers of the single nucleotide polymorphism (SNP) rs1360780. Understanding the mechanisms underlying FKBP5 polymorphism‐associated glucocorticoid responsiveness in the CNS will lead to a better understanding of stress regulation or associated pathology. To study these mechanisms, two novel humanized mouse lines were generated. The lines carried either the risk (A/T) allele or the resilient (C/G) allele of rs1360780. Primary cells from CNS (astrocytes, microglia, and neurons) were analyzed for their basal expression levels of FKBP5 and their responsiveness to glucocorticoids. Differential expression of FKBP5 was found for these cell types and negatively correlated with the cellular glucocorticoid responsiveness. Astrocytes revealed the strongest transcriptional response, followed by microglia and neurons. Furthermore, the risk allele (A/T) was associated with greater induction of FKBP5 than the resilience allele. Novel FKBP5‐humanized mice display differential glucocorticoid responsiveness due to a single intronic SNP. The vulnerability to stress signaling in the shape of glucocorticoids in the brain correlated with FKBP5 expression levels. The strong responsiveness of astrocytes to glucocorticoids implies astrocytes play a prominent role in the stress response, and in FKBP5‐related differences in glucocorticoid signaling. The novel humanized mouse lines will allow for further study of the role that FKBP5 SNPs have in risk and resilience to stress pathology.

Deficits across multiple behavioral domains align with susceptibility to stress in 129S1/SvImJ mice

Acute physical or psychological stress can elicit adaptive behaviors that allow an organism maintain homeostasis. However, intense and/or prolonged stressors often have the opposite effect, resulting in maladaptive behaviors and curbing goal-directed action; in the extreme, this may contribute to the development of psychiatric conditions like generalized anxiety disorder, major depressive disorder, or post-traumatic stress disorder. While treatment of these disorders generally focuses on reducing reactivity to potentially threatening stimuli, there are in fact impairments across multiple domains including valence, arousal, and cognition. Here, we use the genetically stress-susceptible 129S1 mouse strain to explore the effects of stress across multiple domains. We find that 129S1 mice exhibit a potentiated neuroendocrine response across many environments and paradigms, and that this is associated with reduced exploration, neophobia, decreased novelty- and reward-seeking, and spatial learning and memory impairments. Taken together, our results suggest that the 129S1 strain may provide a useful model for elucidating mechanisms underlying myriad aspects of stress-linked psychiatric disorders as well as potential treatments that may ameliorate symptoms.

Impacts of FKBP5 variants on large-scale brain network connectivity in healthy adults

BACKGROUND

FK506 binding protein 5 (FKBP5) rs1360780 polymorphism has been identified as a molecular genetic marker associated with the dysfunction of the hypothalamic-pituitary-adrenal (HPA) axis. The impact of FKBP5 rs1360780 on the large-scale brain network connectivity in healthy adults is still unknown.

METHODS

479 healthy volunteers (age: 20-80years) completed MRI scans, neuropsychological assessments and blood analysis.All subjects were divided into CC, CT and TT genotypes. Within and between network connectivities (10 sub-networks) were calculated using resting state functional MRI (rs-fMRI) data. The genetic effects and gene-gender/age interaction on large-scale network connectivity were explored.

RESULTS

Compared with CC and CT groups, TT group showed increased intra-connectivity in default mode network (DMN) and increased inter-connectivity mainly distributed among the network of DMN, salience network (SAN), dorsal attention network (DAN), ventral attention network (VAN), subcortical network (SUB), and visual network (VIS). Gene-by-gender and gene-by-age interaction were found in inter-connectivity of DAN to VIS and DMN to FPN, respectively. The altered connectivities correlated with anxiety status test score.

LIMITATIONS

Plasma adrenocorticotropic hormone (ACTH) or cortisol were not measured,or else, we could estimate the hypothalamic-pituitary-adrenal (HPA) axis activity which may strengthen our results.

CONCLUSIONS

FKBP5 rs1360780 modulates the large-scale brain network connectivity in healthy adults. TT carriers showed the increased intra- and inter-connectivities mainly distributed among the network of DMN, SAN, DAN, VAN, SUB and VIS.

Epigenetics and depression

The risk for major depression is both genetically and environmentally determined. It has been proposed that epigenetic mechanisms could mediate the lasting increases in depression risk following exposure to adverse life events and provide a mechanistic framework within which genetic and environmental factors can be integrated. Epigenetics refers to processes affecting gene expression and translation that do not involve changes in the DNA sequence and include DNA methylation (DNAm) and microRNAs (miRNAs) as well as histone modifications. Here we review evidence for a role of epigenetics in the pathogenesis of depression from studies investigating DNAm, miRNAs, and histone modifications using different tissues and various experimental designs. From these studies, a model emerges where underlying genetic and environmental risk factors, and interactions between the two, could drive aberrant epigenetic mechanisms targeting stress response pathways, neuronal plasticity, and other behaviorally relevant pathways that have been implicated in major depression.
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Interaction between FKBP5 polymorphisms and childhood trauma on depressive symptoms in Chinese adolescents: The moderating role of resilience

BACKGROUND

Previous gene-environment studies on depression have examined the interaction between FKBP5 gene and childhood trauma, but the results are inconsistent and few studies have focused on Asian adolescents. Psychological resilience may explain for the inconsistency. We examined the interaction between FKBP5 gene and childhood trauma on depressive symptoms in Chinese adolescents, and firstly explored the moderating role of resilience in the relationship.

METHODS

This study comprised 942 participants (448 males, 47.6%) randomly recruited from four senior schools in Wuhan, Hubei of China. Depressive symptoms, childhood trauma, and resilience were respectively evaluated by the Center for Epidemiological Studies Depression Scale (CES-D), the Childhood Trauma Questionnaire (CTQ) and the Connor-Davidson Resilience Scale (CD-RISC). Three potentially functional FKBP5 polymorphisms were selected for genotyping.

RESULTS

Participants carrying minor alleles of FKBP5 polymorphisms (rs3800373, rs1360780, and rs4713916) and a haplotype derived from these variants displayed higher CES-D scores when exposed to childhood physical abuse after adjusting for demographic characteristics and resilience (all P < 0.01). The three-way interactions of FKBP5 SNPs, physical abuse, and resilience on depressive symptoms all yielded statistical significance after adjusting for demographic characteristics (β = -0.282 to -0.236; all P < 0.001).

LIMITATIONS

Cross-sectional design, self- reported measurements and limited genotyped FKBP5 polymorphisms.

CONCLUSION

FKBP5 variants in combination with childhood physical abuse may increase more pronounced depressive symptoms among Chinese adolescents, while resilience plays a moderating role in the associations. Future research to examine the exact mechanism of resilience in these associations is needed.

Understanding the Complex of Suicide in Depression: from Research to Clinics

OBJECTIVE

Amongst psychiatric disorders, major depressive disorder (MDD) is the most prevalent, by affecting approximately 15-17% of the population and showing a high suicide risk rate equivalent to around 15%. The present comprehensive overview aims at evaluating main research studies in the field of MDD at suicide risk, by proposing as well as a schematic suicide risk stratification and useful flow-chart for planning suicide preventive and therapeutic interventions for clinicians.

METHODS

A broad and comprehensive overview has been here conducted by using PubMed/Medline, combining the search strategy of free text terms and exploded MESH headings for the topics of 'Major Depressive Disorder' and 'Suicide' as following: ((suicide [Title/Abstract]) AND (major depressive disorder [Title/Abstract])). All articles published in English through May 31, 2019 were summarized in a comprehensive way.

RESULTS

Despite possible pathophysiological factors which may explain the complexity of suicide in MDD, scientific evidence supposed the synergic role of genetics, exogenous and endogenous stressors (i.e., interpersonal, professional, financial, as well as psychiatric disorders), epigenetic, the hypothalamic-pituitary-adrenal stress-response system, the involvement of the monoaminergic neurotransmitter systems, particularly the serotonergic ones, the lipid profile, neuro-immunological biomarkers, the Brain-derived neurotrophic factor and other neuromodulators.

CONCLUSION

The present overview reported that suicide is a highly complex and multifaceted phenomenon in which a large plethora of mechanisms could be variable implicated, particularly amongst MDD subjects. Beyond these consideration, modern psychiatry needs a better interpretation of suicide risk with a more careful assessment of suicide risk stratification and planning of clinical and treatment interventions.

MicroRNA mediators of early life stress vulnerability to depression and suicidal behavior

Childhood environment can have a profound impact on brain structure and function. Epigenetic mechanisms have been shown to play a critical role in adaptive and maladaptive processes by regulating gene expression without changing the genome. Over the past few years, early life stress (ELS) has been established as a major risk factor for major depression and suicidal behavior along with other psychiatric illnesses in adulthood. In recent years, the emergence of small noncoding RNAs as a mega controller of gene expression has gained attention for their role in various disease processes. Among various noncoding RNAs, microRNAs (miRNAs) are the most studied and well characterized and have emerged as a major regulator of neural plasticity and higher brain functioning. More recently, although limited in number, studies are focusing on how miRNAs can play a role in the maladaptive processes associated with ELS both at adolescent and adult age and whether these processes are critical in developing depression and suicidal behavior. In this review, we critically evaluate how postnatal ELS relates to abnormalities in miRNA expression and functions from both animal and human literature and draw connections from these findings to depression and suicidal behavior later in life.

Gene-environment interactions between HPA-axis genes and childhood maltreatment in depression: a systematic review

OBJECTIVE

Gene-environment (GxE) interactions may comprise an important part of the aetiology of depression, and childhood maltreatment (CM), a significant stressor, has consistently been linked to depression. Hence, in this systematic review, we aimed to investigate the interaction between hypothalamus-pituitary-adrenal axis (HPA-axis) genes and CM in depression.

METHODS

We conducted a literature search using the Pubmed, Embase, and PsychINFO databases in adherence with the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. We included studies investigating GxE interactions between HPA-axis genes [Angiotensin Converting Enzyme (ACE), Arginine Vasopressin (AVP), Corticotrophin Releasing Hormone (CRH), Corticotrophin Releasing Hormone Receptor 1 (CRHR1), Corticotrophin Releasing Hormone Receptor 2 (CRHR2), FK506 binding protein (FKBP5), Nuclear Receptor subfamily 3 group C member 1 (NR3C1), Nuclear Receptor subfamily 3 group C member 2 (NR3C2)] and CM in depression.

RESULTS

The literature search identified 159 potentially relevant studies. Following screening, 138 of these were excluded. Thus, 21 studies, investigating a total of 51 single nucleotide polymorphisms, were included in the final study. The most prevalent genes in the current study were CRHR1 and FKBP5. Significant GxE interactions were reported in seven of eight studies for CRHR1:rs110402 and CM, and in five of eight studies for FKBP5:rs1360780 and CM. In summary, our results suggest possible GxE interactions between CRHR1, FKBP5, NR3C1, and NR3C2 and CM, respectively. For the remaining genes, no relevant literature emerged.

CONCLUSIONS

We find that genetic variation in four HPA-axis genes may influence the effects of CM in depression.

The Devastating Clinical Consequences of Child Abuse and Neglect: Increased Disease Vulnerability and Poor Treatment Response in Mood Disorders

A large body of evidence has demonstrated that exposure to childhood maltreatment at any stage of development can have long-lasting consequences. It is associated with a marked increase in risk for psychiatric and medical disorders. This review summarizes the literature investigating the effects of childhood maltreatment on disease vulnerability for mood disorders, specifically summarizing cross-sectional and more recent longitudinal studies demonstrating that childhood maltreatment is more prevalent and is associated with increased risk for first mood episode, episode recurrence, greater comorbidities, and increased risk for suicidal ideation and attempts in individuals with mood disorders. It summarizes the persistent alterations associated with childhood maltreatment, including alterations in the hypothalamic-pituitary-adrenal axis and inflammatory cytokines, which may contribute to disease vulnerability and a more pernicious disease course. The authors discuss several candidate genes and environmental factors (for example, substance use) that may alter disease vulnerability and illness course and neurobiological associations that may mediate these relationships following childhood maltreatment. Studies provide insight into modifiable mechanisms and provide direction to improve both treatment and prevention strategies.

FKBP5 Genotype Linked to Combined PTSD-Depression Symptom in Chinese Earthquake Survivors

BACKGROUND

Post-traumatic stress disorder (PTSD) and depression are common mental disorders in individuals experiencing traumatic events. To date, few studies have studied the relationship between genetic basis and phenotypic heterogeneity of traumatized individuals. The present study examined the effects of four FKBP5 SNPs (rs1360780, rs3800373, rs9296158, and rs9470080) in four postdisaster groups (low symptom, predominantly depressive, predominantly PTSD, and combined PTSD-depression symptom groups) as identified by latent profile analysis.

METHODS

A total of 1,140 adults who experienced the 2008 Wenchuan earthquake participated in our study. Earthquake-related trauma, PTSD, and depressive symptoms were measured using standard psychometric instruments. The four FKBP5 SNPs were genotyped using a custom-by-design 2 × 48-Plex SNP scan™ Kit.

RESULTS

After adjusting for covariates, the main and gene-environment interaction effects of rs9470080 were all significant when the combined PTSD-depression group was compared with the low symptoms, predominantly depression and predominantly PTSD groups. rs9470080 TT genotype carriers had a higher risk of developing high co-occurring PTSD and depression symptoms than the C allele carriers. However, when trauma exposure was severe, the TT genotype carriers and C allele carriers did not differ in the risk of developing high co-occurring PTSD and depressive symptoms. The other three SNPs demonstrated no significant effects. Moreover, the rs3800373-rs9296158-rs1360780-rs9470080 haplotype A-G-C-T was found significantly associated with combined PTSD-depression symptoms.

CONCLUSION

Our findings support the genetic basis of phenotypic heterogeneity in people exposed to trauma. Furthermore, the results reveal the possibility that the variants of FKBP5 gene may be associated with depression-PTSD comorbidity.

Genetics of Resilience: Gene-by-Environment Interaction Studies as a Tool to Dissect Mechanisms of Resilience

The identification and understanding of resilience mechanisms holds potential for the development of mechanistically informed prevention and interventions in psychiatry. However, investigating resilience mechanisms is conceptually and methodologically challenging because resilience does not merely constitute the absence of disease-specific risk but rather reflects active processes that aid in the maintenance of physiological and psychological homeostasis across a broad range of environmental circumstances. In this conceptual review, we argue that the principle used in gene-by-environment interaction studies may help to unravel resilience mechanisms on different investigation levels. We present how this could be achieved by top-down designs that start with gene-by-environment interaction effects on disease phenotypes as well as by bottom-up approaches that start at the molecular level. We also discuss how recent technological advances may improve both top-down and bottom-up strategies.

Epigenetics and Depression: An Update

OBJECTIVE

Depression is associated with various environmental risk factors such as stress, childhood maltreatment experiences, and stressful life events. Current approaches to assess the pathophysiology of depression, such as epigenetics and gene-environment (GxE) interactions, have been widely leveraged to determine plausible markers, genes, and variants for the risk of developing depression.

METHODS

We focus on the most recent developments for genomic research in epigenetics and GxE interactions.

RESULTS

In this review, we first survey a variety of association studies regarding depression with consideration of GxE interactions. We then illustrate evidence of epigenetic mechanisms such as DNA methylation, microRNAs, and histone modifications to influence depression in terms of animal models and human studies. Finally, we highlight their limitations and future directions.

CONCLUSION

In light of emerging technologies in artificial intelligence and machine learning, future research in epigenetics and GxE interactions promises to achieve novel innovations that may lead to disease prevention and future potential therapeutic treatments for depression.

Interactions between FKBP5 variation and environmental stressors in adolescent Major Depression

OBJECTIVE

Major Depression (MD) results from a complex interplay between environmental stressors and biological factors. Previous studies in adults have shown that adverse life events interact with genetic variation in FKBP5, a gene implicated in the stress-response system, to predict depressive symptoms and MD. This is the first study to investigate interactions between FKBP5 variants and a range of environmental stressors in adolescents with a clinical diagnosis of MD.

METHOD

148 male and female adolescents with MD and 143 typically developing (TD) controls (13-18 years) were included in the present study. For self-reported environmental stressors, subjective severity was assessed to allow a classification of these factors as mild, moderate and severe. Sociodemographic stressors were assessed via parental-report.

RESULTS

With a heightened number of sociodemographic, moderate and total number of stressors, participants carrying at least one copy of the FKBP5 CATT haplotype or at least one minor allele of various FKBP5 SNPs had the highest risk for being in the MD group. No genetic main effects were found. Sociodemographic stressors as well as self-reported mild, moderate, and severe stressors were more common in depressed than in TD adolescents.

CONCLUSION

This is the first study to show interactions between genetic variation in FKBP5 and environmental stressors in a sample of clinically depressed adolescents. The current study provides important starting-points for preventive efforts and highlights the need for a fine-grained analysis of different forms and severities of environmental stressors and their interplay with genetic variation for understanding the complex etiology of (youth) MD.

Clinical association to FKBP5 rs1360780 in patients with depression

The FKBP5 protein is of importance for the function of the glucocorticoid receptor. The purpose of the present study was to examine the possible association between the different genotypes of rs1360780 in the FKBP5 gene, and clinical symptoms in patients with unipolar depression. Seven hundred eighteen patients and 673 controls from the Danish Psychiatric Biobank were participated. No association was found between any genotype and diagnosis of unipolar depression. It was found that the group of depressed patients with the CC genotype showed significantly earlier start of treatment with medicine, had a significantly greater tendency to be treated with electroconvulsive therapy and showed a significantly higher frequency of family history of depression compared with the combined group of patients with the CT and TT genotypes. The only informations about controls were their sex and that they were recruited from the blood bank. The clinical data were not complete for all patients.

Chronic cocaine administration upregulates FKBP5 in the extended amygdala of male and female rats

BACKGROUND

Dysregulation of glucocorticoid receptors has been implicated in addiction and stress-related disorders. FKBP5 is a co-chaperone of the glucocorticoid receptor and regulates receptor sensitivity. While FKBP5 is known to be involved in mood- and stress-related disorders, less is known regarding FKBP5 and cocaine abuse. This study investigated the regulation of FKBP5 expression in the extended amygdala and paraventricular nucleus of the hypothalamus, regions important in the control of stress-responses and HPA axis function, following chronic and acute cocaine administration.

METHODS

Adult male and female rats received saline or cocaine three times per day for 1 or 14 days. Brain tissue was collected 30 min, 24 h, 48 h, 7 days or 14 days following the final injection. FKBP5 mRNA was measured by qRT-PCR in the central nucleus of the amygdala (CeA), bed nucleus of the stria terminalis (BNST) and paraventricular nucleus (PVN).

RESULTS

FKBP5 mRNA levels were significantly elevated as a result of chronic cocaine administration in both males and females in the PVN and BNST 30 min and 24 h after the final injection. In females, FKBP5 was also elevated in the CeA. Following acute cocaine, FKBP5 gene expression was unaltered except for elevated levels in the BNST of females 24 h later.

CONCLUSIONS

These results demonstrate that FKBP5 mRNA is regulated by cocaine administration. Increased FKBP5 expression may play a role in the dysregulation of the stress axis following chronic cocaine exposure, contributing to the negative affective symptoms of cocaine withdrawal.