Using polymorphisms in FKBP5 to define biologically distinct subtypes of posttraumatic stress disorder: evidence from endocrine and gene expression studies

Reversibility of disturbed pituitary function in pediatric conditions with psychological stressors: implications for clinical practice

The complex communication network between the central nervous system and the hypothalamic-pituitary axis forms the basis of endocrine functional plasticity, which facilitates adaptation to changing internal and external conditions, but also makes it vulnerable to the negative effects of stressful psychological factors. Herein, clinical conditions such as functional hypothalamic amenorrhea, eating disorders, growth faltering, post-traumatic stress disorder, and pubertal disorders that may emerge during childhood or adolescence, their origin possibly including psychological stressors, are analyzed regarding their genetic susceptibility and reversibility of endocrine function. A discussion on the optimization of therapeutic management defined by managing stress and maximizing the degree and rate of reversibility follows.

Considering hormones as sex- and gender-related factors in biomedical research: Challenging false dichotomies and embracing complexity

The inclusion of sex and gender considerations in biomedicine has been increasing in light of calls from research and funding agencies, governmental bodies, and advocacy groups to direct research attention to these issues. Although the inclusion of both female and male participants is often an important element, overreliance on a female-male binary tends to oversimplify the interactions between sex- and gender-related factors and health, and runs a risk of being influenced by cultural stereotypes about sex and gender. When biomedical researchers are examining how hormones associated with gender and sex may influence pathways of interest, it is of crucial importance to approach this work with a critical lens on the rhetoric used, and in ways that acknowledge the complexity of hormone physiology. Here, we document the ways in which discourses around sex, gender and hormones shape our scientific thinking and practice in biomedical research, and review how the existing scientific knowledge about hormones reflects a complex and dynamic reality that is often not reflected outside of specialist niches of hormone biology. Where biomedical scientists take up sex- and gender-associated hormones as a way of addressing sex and gender considerations, it is valuable for us to bring a critical lens to the rhetoric and discourses used, to employ a sex contextualist approach in designing experimentation, and be rigorous and reflexive about the approaches used in analysis and interpretation of data. These strategies will allow us to design experimentation that goes beyond binaries, and grapples more directly with the material intricacies of sex, gender, and hormones.

IL-18 Signaling in the Rat Central Amygdala Is Disrupted in a Comorbid Model of Post-Traumatic Stress and Alcohol Use Disorder

Alcohol use disorder (AUD) and anxiety disorders are frequently comorbid and share dysregulated neuroimmune-related pathways. Here, we used our established rat model of comorbid post-traumatic stress disorder (PTSD)/AUD to characterize the interleukin 18 (IL-18) system in the central amygdala (CeA). Male and female rats underwent novel (NOV) and familiar (FAM) shock stress, or no stress (unstressed controls; CTL) followed by voluntary alcohol drinking and PTSD-related behaviors, then all received renewed alcohol access prior to the experiments. In situ hybridization revealed that the number of CeA positive cells for Il18 mRNA increased, while for Il18bp decreased in both male and female FAM stressed rats versus CTL. No changes were observed in Il18r1 expression across groups. Ex vivo electrophysiology showed that IL-18 reduced GABAA-mediated miniature inhibitory postsynaptic currents (mIPSCs) frequencies in CTL, suggesting reduced CeA GABA release, regardless of sex. Notably, this presynaptic effect of IL-18 was lost in both NOV and FAM males, while it persisted in NOV and FAM females. IL-18 decreased mIPSC amplitude in CTL female rats, suggesting postsynaptic effects. Overall, our results suggest that stress in rats with alcohol access impacts CeA IL-18-system expression and, in sex-related fashion, IL-18's modulatory function at GABA synapses.

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.

Glucocorticoid-based pharmacotherapies preventing PTSD

Posttraumatic stress disorder (PTSD) is a highly disabling psychiatric condition that may arise after exposure to acute and severe trauma. It is a highly prevalent mental disorder worldwide, and the current treatment options for these patients remain limited due to low effectiveness. The time window right after traumatic events provides clinicians with a unique opportunity for preventive interventions against potential deleterious alterations in brain function that lead to PTSD. Some studies pointed out that PTSD patients present an abnormal function of the hypothalamic-pituitary-adrenal axis that may contribute to a vulnerability toward PTSD. Moreover, glucocorticoids have arisen as a promising option for preventing the disorder's development when administered in the aftermath of trauma. The present work compiles the recent findings of glucocorticoid administration for the prevention of a PTSD phenotype, from human studies to animal models of PTSD. Overall, glucocorticoid-based therapies for preventing PTSD demonstrated moderate evidence in terms of efficacy in both clinical and preclinical studies. Although clinical studies point out that glucocorticoids may not be effective for all patients' subpopulations, those with adequate traits might greatly benefit from them. Preclinical studies provide precise insight into the mechanisms mediating this preventive effect, showing glucocorticoid-based prevention to reduce long-lasting behavioral and neurobiological abnormalities caused by traumatic stress. However, further research is needed to delineate the precise mechanisms and the extent to which these interventions can translate into lower PTSD rates and morbidity. This article is part of the Special Issue on 'Fear, Anxiety and PTSD'.

Regulatory Effects of Maternal Immune Activation and Environmental Enrichment on Glucocorticoid Receptor and FKBP5 Expression in Stress-sensitive Regions of the Offspring Brain

A mother's exposure to immune challenge during pregnancy is well known to be a detrimental factor to the development of the offspring's brain and an impetus for neuropsychiatric disorders. Previous studies have shown that these adverse events can dysregulate the stress response machinery. Two crucial components of the stress axis considered to be affected have been targets in these studies: the glucocorticoid receptor (GR), and FKBP5 which regulates GR activity. The implementation of interventions such as Environmental Enrichment (EE) have shown positive results in protecting the brain against the consequences associated with gestational insults. In light of this, we investigated the transcriptional regulation of GR and FKBP5 from six stress-sensitive brain regions of the offspring using a rat model of maternal immune activation (MIA). Furthermore, we analyzed the effect of an enriched environment on their expression. We found an increase in FKBP5 in MIA rats in five brain regions. RT-qPCR analysis of MIA's effect on GR yielded insignificant results. However, we found that EE increased GR expression in the medial preoptic area which could be indicative of a positive regulation by EE. This study provides evidence of the impact of both gestational insult and EE on the regulation of stress responsive genes in the developing brain.

Epigenetic Age Acceleration and Risk for Posttraumatic Stress Disorder following Exposure to Substantiated Child Maltreatment

OBJECTIVE

Child maltreatment is among the strongest predictors of posttraumatic stress disorder (PTSD). However, less than 40% of children who have been maltreated are ever diagnosed with PTSD, suggesting that exposure to child maltreatment alone is insufficient to explain this risk. This study examined whether epigenetic age acceleration, a stress-sensitive biomarker derived from DNA methylation, explains variation in PTSD diagnostic status subsequent to child maltreatment.

METHOD

Children and adolescents (N = 70; 65.7% female), 8-15 years of age (M = 12.00, SD = 2.37) and exposed to substantiated child maltreatment within the 12 months prior to study entry, were enrolled. Participants provided epithelial cheek cells via buccal swab for genotyping and quantification of epigenetic age acceleration within a case-control design. PTSD diagnostic status was determined using the Child PTSD Symptoms Scale according to the DSM-IV-TR algorithm.

RESULTS

Epigenetic age acceleration predicted current PTSD status, revealing an effect size magnitude in the moderate range, OR = 2.35, 95% CI: 1.22- 4.51, after adjusting for sample demographics, polygenic risk for PTSD, and lifetime exposure to other childhood adversities. Supplemental analyses demonstrated that epigenetic age acceleration was related to a greater severity of PTSD arousal symptoms (r =.29, p =.015). There were no differential effects for child maltreatment subtype on epigenetic age acceleration or PTSD status.

CONCLUSIONS

The biological embedding of child maltreatment may explain variation in PTSD diagnostic status and serve as a novel approach for informing selective prevention or precision-based therapeutics for those at risk for PTSD.

Invisible wounds: Suturing the gap between the neurobiology, conventional and emerging therapies for posttraumatic stress disorder

A sharp increase in the prevalence of neuropsychiatric disorders, including major depression, anxiety, substance use disorders and posttraumatic stress disorder (PTSD) has occurred due to the traumatic nature of the persisting COVID-19 global pandemic. PTSD is estimated to occur in up to 25% of individuals following exposure to acute or chronic trauma, and the pandemic has inflicted both forms of trauma on much of the population through both direct physiological attack as well as an inherent upheaval to our sense of safety. However, despite significant advances in our ability to define and apprehend the effects of traumatic events, the neurobiology and neuroanatomical circuitry of PTSD, one of the most severe consequences of traumatic exposure, remains poorly understood. Furthermore, the current psychotherapies or pharmacological options for treatment have limited efficacy, durability, and low adherence rates. Consequently, there is a great need to better understand the neurobiology and neuroanatomy of PTSD and develop novel therapies that extend beyond the current limited treatments. This review summarizes the neurobiological and neuroanatomical underpinnings of PTSD and discusses the conventional and emerging psychotherapies, pharmacological and combined psychopharmacological therapies, including the use of psychedelic-assisted psychotherapies and neuromodulatory interventions, for the improved treatment of PTSD and the potential for their wider applications in other neuropsychiatric disorders resulting from traumatic exposure.

Child maltreatment and hypothalamic-pituitary-adrenal axis functioning: A systematic review and meta-analysis

Alterations in hypothalamic-pituitary-adrenal (HPA) axis and its effector hormone cortisol have been proposed as one possible mechanism linking child maltreatment experiences to health disparities. In this series of meta-analyses, we aimed to quantify the existing evidence on the effect of child maltreatment on various measures of HPA axis activity. The systematic literature search yielded 1,858 records, of which 87 studies (k = 132) were included. Using random-effects models, we found evidence for blunted cortisol stress reactivity in individuals exposed to child maltreatment. In contrast, no overall differences were found in any of the other HPA axis activity measures (including measures of daily activity, cortisol assessed in the context of pharmacological challenges and cumulative measures of cortisol secretion). The impact of several moderators (e.g., sex, psychopathology, study quality), the role of methodological shortcomings of existing studies, as well as potential directions for future research are discussed.

Recalibrating the epigenetic clock after exposure to trauma: The role of risk and protective psychosocial factors

BACKGROUND

Epigenetic aging is associated with a plethora of negative health outcomes and increased mortality. Yet, the dynamicity of epigenetic age after exposure to trauma and the factors that influence epigenetic age are not fully understood. This research evaluated longitudinal changes in epigenetic age before and after exposure to work-related trauma among paramedicine students. We further investigated psychological and social risk (psychological distress, posttraumatic stress disorder/PTSD symptom severity, professional quality of life) and protective factors (social support and organisational membership) that drive epigenetic aging at both time points.

METHODS

The study comprised of 80 samples of University paramedicine students including 40 individuals at two time points - t0 (baseline) and t1 (post-trauma exposure). Epigenome-wide analysis was performed from t0 and t1 saliva using the Illumina EPIC arrays that cover >860k probes. Data analysis was performed using R via generalized regression models. The epigenetic age was calculated based on the Horvath algorithm, GrimAge and SkinBloodAge were calculated using the Horvath online calculator, and p-value for significance was corrected using the FDR method for multiple testing corrections.

RESULTS

The epigenetic age at t0 and t1 were highly correlated with chronological age and with each other (r = 0.84-0.94). Baseline epigenetic age and follow-up epigenetic age were significantly associated with risk factors of psychological distress and PTSD symptom severity. Among the protective factors, a sense of psychological organisational membership at the start of the paramedicine course as measured at baseline significantly reduced epigenetic age at baseline and post-trauma exposure. On the other hand, receiving social support acted as a protective factor only after exposure to trauma (follow-up), decreasing epigenetic aging at follow-up. GrimAge acceleration at follow-up was significantly associated with increased PTSD symptom severity at baseline and follow-up. Moreover, increased social support at baseline and follow-up was associated with reduced follow-up GrimAge acceleration.

CONCLUSION

These results demonstrate that epigenetic aging is dynamic and changes after exposure to trauma. Additionally, results demonstrate that different risk and protective factors influence epigenetic aging at different times. In conclusion, the research identified risk and protective factors associated with epigenetic aging pre- and post-trauma exposure, with implications for health and well-being among individuals exposed to trauma.

Integrated Analysis of miRNA and mRNA Expression Profiles Reveals the Molecular Mechanism of Posttraumatic Stress Disorder and Therapeutic Drugs

Purpose

Post-traumatic stress disorder (PTSD) is a result of trauma exposure and is related to psychological suffering as a long-lasting health issue. Further analysis of the networks and genes involved in PTSD are critical to the molecular mechanisms of PTSD.

Methods

In this study, we aimed to identify key genes and molecular interaction networks involved in the pathogenesis of PTSD by integrating mRNA and miRNA data.

Results

By integrating three high-throughput datasets, 5606 differentially expressed genes (DEGs) were detected, including five differentially expressed miRNAs (DEmiRNAs) and 5525 differentially expressed mRNAs (DEmRNAs). Nineteen upregulated and 46 downregulated DEmRNAs were identified in both GSE64813 and GSE89866 datasets, while five upregulated DEmiRNAs were found in the GSE87768 dataset. Functional annotations of these DEmRNAs indicated that they were mainly enriched in blood coagulation, cell adhesion, platelet activation, and extracellular matrix (ECM)-receptor interaction. Integrated protein-protein and miRNA-protein interaction networks among the DEGs were established with the help of 65 nodes and 121 interactions. Finally, 286 small molecules were obtained based on the Drug-Gene Interaction database (DGIdb). Three genes, prostaglandin-endoperoxide synthase 1 (PTGS1), beta-tubulin gene (TUBB1), and cyclin-dependent kinase inhibitor 1A (CDKN1A), were the most promising targets for PTSD therapy. Additionally, the present study also provided a higher performance diagnostic model for PTSD based on 17 DEmRNAs, which was validated in two independent datasets, GSE109409 and GSE63878.

Conclusion

Our data provides a new molecular aspect that ECM-receptor interaction and the platelet activation process could be the potential molecular mechanism of PTSD, and the genes involved in this process may be promising therapeutic targets. A higher-performance diagnostic model for PTSD has also been identified.

Gene Expression Analysis in Three Posttraumatic Stress Disorder Cohorts Implicates Inflammation and Innate Immunity Pathways and Uncovers Shared Genetic Risk With Major Depressive Disorder

Posttraumatic stress disorder (PTSD) is a complex psychiatric disorder that can develop following exposure to traumatic events. The Psychiatric Genomics Consortium PTSD group (PGC-PTSD) has collected over 20,000 multi-ethnic PTSD cases and controls and has identified both genetic and epigenetic factors associated with PTSD risk. To further investigate biological correlates of PTSD risk, we examined three PGC-PTSD cohorts comprising 977 subjects to identify differentially expressed genes among PTSD cases and controls. Whole blood gene expression was quantified with the HumanHT-12 v4 Expression BeadChip for 726 OEF/OIF veterans from the Veterans Affairs (VA) Mental Illness Research Education and Clinical Center (MIRECC), 155 samples from the Injury and Traumatic Stress (INTRuST) Clinical Consortium, and 96 Australian Vietnam War veterans. Differential gene expression analysis was performed in each cohort separately followed by meta-analysis. In the largest cohort, we performed co-expression analysis to identify modules of genes that are associated with PTSD and MDD. We then conducted expression quantitative trait loci (eQTL) analysis and assessed the presence of eQTL interactions involving PTSD and major depressive disorder (MDD). Finally, we utilized PTSD and MDD GWAS summary statistics to identify regions that colocalize with eQTLs. Although not surpassing correction for multiple testing, the most differentially expressed genes in meta-analysis were interleukin-1 beta (IL1B), a pro-inflammatory cytokine previously associated with PTSD, and integrin-linked kinase (ILK), which is highly expressed in brain and can rescue dysregulated hippocampal neurogenesis and memory deficits. Pathway analysis revealed enrichment of toll-like receptor (TLR) and interleukin-1 receptor genes, which are integral to cellular innate immune response. Co-expression analysis identified four modules of genes associated with PTSD, two of which are also associated with MDD, demonstrating common biological pathways underlying the two conditions. Lastly, we identified four genes (UBA7, HLA-F, HSPA1B, and RERE) with high probability of a shared causal eQTL variant with PTSD and/or MDD GWAS variants, thereby providing a potential mechanism by which the GWAS variant contributes to disease risk. In summary, we provide additional evidence for genes and pathways previously reported and identified plausible novel candidates for PTSD. These data provide further insight into genetic factors and pathways involved in PTSD, as well as potential regions of pleiotropy between PTSD and MDD.

Perinatal stress and epigenetics

Animal and humans exposed to stress early in life are more likely to suffer from long-term behavioral, mental health, metabolic, immune, and cardiovascular health consequences. The hypothalamus plays a nodal role in programming, controlling, and regulating stress responses throughout the life course. Epigenetic reprogramming in the hippocampus and the hypothalamus play an important role in adapting genome function to experiences and exposures during the perinatal and early life periods and setting up stable phenotypic outcomes. Epigenetic programming during development enables one genome to express multiple cell type identities. The most proximal epigenetic mark to DNA is a covalent modification of the DNA itself by enzymatic addition of methyl moieties. Cell-type-specific DNA methylation profiles are generated during gestational development and define cell and tissue specific phenotypes. Programming of neuronal phenotypes and sex differences in the hypothalamus is achieved by developmentally timed rearrangement of DNA methylation profiles. Similarly, other stations in the life trajectory such as puberty and aging involve predictable and scheduled reorganization of DNA methylation profiles. DNA methylation and other epigenetic marks are critical for maintaining cell-type identity in the brain, across the body, and throughout life. Data that have emerged in the last 15 years suggest that like its role in defining cell-specific phenotype during development, DNA methylation might be involved in defining experiential identities, programming similar genes to perform differently in response to diverse experiential histories. Early life stress impact on lifelong phenotypes is proposed to be mediated by DNA methylation and other epigenetic marks. Epigenetic marks, as opposed to genetic mutations, are reversible by either pharmacological or behavioral strategies and therefore offer the potential for reversing or preventing disease including behavioral and mental health disorders. This chapter discusses data testing the hypothesis that DNA methylation modulations of the HPA axis mediate the impact of early life stress on lifelong behavioral and physical phenotypes.

The Neurocircuitry of Posttraumatic Stress Disorder and Major Depression: Insights Into Overlapping and Distinct Circuit Dysfunction-A Tribute to Ron Duman

The neurocircuitry that contributes to the pathophysiology of posttraumatic stress disorder and major depressive disorder, psychiatric conditions that exhibit a high degree of comorbidity, likely involves both overlapping and unique structural and functional changes within multiple limbic brain regions. In this review, we discuss neurobiological alterations that are associated with posttraumatic stress disorder and major depressive disorder and highlight both similarities and differences that may exist between these disorders to argue for the existence of a shared neurobiology. We highlight the key contributions based on preclinical studies, emerging from the late Professor Ronald Duman's research, that have shaped our understanding of the neurocircuitry that contributes to both the etiopathology and treatment of major depressive disorder and posttraumatic stress disorder.

Myelination defects in the medial prefrontal cortex of Fkbp5 knockout mice

The hypothalamic-pituitary-adrenal (HPA) axis plays a principal role in stress response regulation and has been implicated in the etiology of stress-related disorders. The HPA axis regulates the normal synthesis and release of glucocorticoids; dysregulation of the HPA axis causes abnormal responses to stress. FK506-binding protein 5 (FKBP5), a co-chaperone of heat shock protein 90 in the glucocorticoid receptor (GR) molecular complex, is a key GR sensitivity regulator. FKBP5 single nucleotide polymorphisms are associated with dysregulated HPA axis and increased risk of stress-related disorders, including posttraumatic stress disorder (PTSD) and depression. In this study, we profiled the microRNAs (miRNAs) in the medial prefrontal cortex of Fkbp5 knockout (Fkbp5^-/- ) mice and identified the target genes of differentially expressed miRNAs using sequence-based miRNA target prediction. Gene ontology analysis revealed that the differentially expressed miRNAs were involved in nervous system development, regulation of cell migration, and intracellular signal transduction. The validation of the expression of predicted target genes using quantitative polymerase chain reaction revealed that the expression of axon development-related genes, specifically actin-binding LIM protein 1 (Ablim1), lemur tyrosine kinase 2 (Lmtk2), kinesin family member 5c (Kif5c), neurofascin (Nfasc), and ephrin type-A receptor 4 (Epha4), was significantly decreased, while that of brain-derived neurotrophic factor (Bdnf) was significantly increased in the brain of Fkbp5^-/- mice. These results suggest that axonal development-related genes can serve as potential targets in future studies focused on understanding the pathophysiology of PTSD.

Methyl-CpG binding protein 2 dysfunction provides stress vulnerability with sex- and zygosity-dependent outcomes

Stress vulnerability is a critical factor for the development of trauma-related disorders; however, its biological underpinnings are not clear. We demonstrated that dysfunctions in the X-linked epigenetic factor methyl-CpG binding protein 2 (MeCP2) provide trauma vulnerability in male mice. Given the prominent role of sex in stress outcomes, we explored the effects of MeCP2 hypofunctionality in females. Female mice carrying truncated MeCP2 (heterozygous and homozygous) and wild type controls (wt) were tested for fear memory. Stress-induced corticosterone release and brain expression of hypothalamic-pituitary-adrenal (HPA) axis regulatory genes were also evaluated in wt and mutant mice of both sexes. Although heterozygous females displayed a normal stress-related behavioural profile, homozygous mice showed enhanced memory recall for the threatening context compared to wt, thus recapitulating the phenotype previously evidenced in hemizygous males. Interestingly, MeCP2 truncation abolished the sex differences in stress-induced corticosterone release, which was found increased in mutant males, whereas blunted in mutant females in a zygosity-independent manner. Although heterozygous mice did not differ from controls, homozygous females and hemizygous males showed increased hypotalamic Crh and Avp mRNAs and a differentially altered expression of Fkbp5 in cortical areas. Present results demonstrate that in female mice carrying truncated MeCP2, altered stress responsivity is driven by homozygosity, whereas heterozygosity does not lead to maladaptive stress outcomes. MeCP2 dysfunctions thus provide stress vulnerability in mice with sex- and zygosity-dependent outcomes.

The Pathways between Cortisol-Related Regulation Genes and PTSD Psychotherapy

Post-traumatic stress disorder (PTSD) only develops after exposure to a traumatic event in some individuals. PTSD can be chronic and debilitating, and is associated with co-morbidities such as depression, substance use, and cardiometabolic disorders. One of the most important pathophysiological mechanisms underlying the development of PTSD and its subsequent maintenance is a dysfunctional hypothalamic-pituitary-adrenal (HPA) axis. The corticotrophin-releasing hormone, cortisol, glucocorticoid receptor (GR), and their respective genes are some of the mediators of PTSD's pathophysiology. Several treatments are available, including medication and psychotherapies, although their success rate is limited. Some pharmacological therapies based on the HPA axis are currently being tested in clinical trials and changes in HPA axis biomarkers have been found to occur in response not only to pharmacological treatments, but also to psychotherapy-including the epigenetic modification of the GR gene. Psychotherapies are considered to be the first line treatments for PTSD in some guidelines, even though they are effective for some, but not for all patients with PTSD. This review aims to address how knowledge of the HPA axis-related genetic makeup can inform and predict the outcomes of psychotherapeutic treatments.

Epigenetic landscape of stress surfeit disorders: Key role for DNA methylation dynamics

Chronic exposure to stress throughout lifespan alters brain structure and function, inducing a maladaptive response to environmental stimuli, that can contribute to the development of a pathological phenotype. Studies have shown that hypothalamic-pituitary-adrenal (HPA) axis dysfunction is associated with various neuropsychiatric disorders, including major depressive, alcohol use and post-traumatic stress disorders. Downstream actors of the HPA axis, glucocorticoids are critical mediators of the stress response and exert their function through specific receptors, i.e., the glucocorticoid receptor (GR), highly expressed in stress/reward-integrative pathways. GRs are ligand-activated transcription factors that recruit epigenetic actors to regulate gene expression via DNA methylation, altering chromatin structure and thus shaping the response to stress. The dynamic interplay between stress response and epigenetic modifiers suggest DNA methylation plays a key role in the development of stress surfeit disorders.

The glucocorticoid receptor-FKBP51 complex contributes to fear conditioning and posttraumatic stress disorder

Posttraumatic stress disorder (PTSD) can develop after exposure to severe psychological trauma, leaving patients with disabling anxiety, nightmares, and flashbacks. Current treatments are only partially effective, and development of better treatments is hampered by limited knowledge of molecular mechanisms underlying PTSD. We have discovered that the glucocorticoid receptor (GR) and FK506 binding protein 51 (FKBP51) form a protein complex that is elevated in PTSD patients compared with unaffected control subjects, subjects exposed to trauma without PTSD, and patients with major depressive disorder (MDD). The GR-FKBP51 complex is also elevated in fear-conditioned mice, an aversive learning paradigm that models some aspects of PTSD. Both PTSD patients and fear-conditioned mice had decreased GR phosphorylation, decreased nuclear GR, and lower expression of 14-3-3ε, a gene regulated by GR. We created a peptide that disrupts GR-FKBP51 binding and reverses behavioral and molecular changes induced by fear conditioning. This peptide reduces freezing time and increases GR phosphorylation, GR-FKBP52 binding, GR nuclear translocation, and 14-3-3ε expression in fear-conditioned mice. These experiments demonstrate a molecular mechanism contributing to PTSD and suggest that the GR-FKBP51 complex may be a diagnostic biomarker and a potential therapeutic target for preventing or treating PTSD.

Expression profile and bioinformatics analysis of circular RNA in intestinal mucosal injury and repair after severe burns

Circular RNA (circRNA) is a novel noncoding RNA that is mostly found in humans and animals. Although the flux of circRNA research has increased in recent years, its precise function is still unclear. Some studies demonstrate that circRNAs can function as microRNA (miRNA) sponges involved in the regulation of competitive endogenous RNAs networks and play a crucial role in many biological processes. Other studies show that circRNAs play multiple biological roles in gastrointestinal diseases. However, the expression characteristics and function of circRNA in intestinal mucosal injury and repair after severe burn have not been reported. This study aims to screen differentially expressed circRNAs in intestinal mucosal injury and repair after severe burns and understand their underlying mechanisms. To test our hypothesis that circRNA may play a role in promoting repair in intestinal mucosa injury after severe burns, we collected the intestinal tissues of three severely burned mice and three pseudo-scalded mice and evaluated the expression of circRNAs via microarray analysis. Quantitative real-time polymerase chain reaction was also used to validate the circRNA microarray data by selecting six based on different multiples, original values, and p values. The host genes of all differentially expressed circRNAs and the downstream target genes of six selected DEcircRNAs were identified by Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes pathway analysis. Meanwhile, we also created a circRNA-miRNA-mRNA network to predict the role and function of circRNAs in intestinal mucosal injury and repair after severe burns.

A Systematic Review of DNA Methylation and Gene Expression Studies in Posttraumatic Stress Disorder, Posttraumatic Growth, and Resilience

Most people will experience a traumatic event within their lifetime. One commonly recognized response to trauma exposure is posttraumatic stress disorder (PTSD). The biological underpinnings of PTSD, including epigenetic mechanisms of DNA methylation and gene expression, have been studied intensively. However, psychological posttrauma responses vary widely and can include positive outcomes, such as posttraumatic growth (PTG) and, more commonly, resilience. The aim of this systematic review was to summarize the current DNA methylation and gene expression data with respect to three potential posttrauma responses: PTSD, PTG, and resilience. A literature search identified 486 studies, 51 of which were deemed eligible for inclusion (total N = 10,633). All included studies examined PTSD and consistently implicated DNA methylation and gene expression changes in hypothalamic-pituitary-adrenal axis and inflammatory genes. Ten studies acknowledged resilience as a posttrauma response, but only two studies examined epigenetics and gene expression using a scale to measure resilience. Low resilience was associated with gene expression patterns in immune and dopamine genes, and high resilience was associated with a blunted inflammatory response. No studies examined epigenetic or gene expression changes associated with PTG. These findings highlight a focus on pathogenic research, which has failed to adequately acknowledge and measure positive posttrauma outcomes of PTG and resilience. Future research should examine DNA methylation and gene expression changes associated with PTG and resilience in addition to PTSD in order to gain a more comprehensive picture of an individual's well-being following exposure to trauma.

Epigenetics, Development, and Psychopathology

Epigenetic mechanisms govern the transcription of the genome. Research with model systems reveals that environmental conditions can directly influence epigenetic mechanisms that are associated with interindividual differences in gene expression in brain and neural function. In this review, we provide a brief overview of epigenetic mechanisms and research with relevant rodent models. We emphasize more recent translational research programs in epigenetics as well as the challenges inherent in the integration of epigenetics into developmental and clinical psychology. Our objectives are to present an update with respect to the translational relevance of epigenetics for the study of psychopathology and to consider the state of current research with respect to its potential importance for clinical research and practice in mental health.

The interaction between estradiol change and the serotonin transporter gene (5-HTTLPR) polymorphism is associated with postpartum depressive symptoms

Although estrogenic fluctuation is considered a major risk factor for postpartum depression (PPD), the effects of the interactions between the genetic background and estradiol (E2) change on PPD are not well understood. Here, a cohort study with 437 postpartum women was carried out to evaluate the role of a serotonin transporter gene polymorphism (5-HTTLPR) and E2 change on the risk of PPD symptoms. The participants were assessed using the Edinburgh Postnatal Depression Scale and the Self-Rating Depression Scale at 1 and 6 weeks after delivery. The PCR-based restriction fragment length polymorphism method was utilized to examine the genotype distribution of the 5-HTTLPR polymorphism, and the serum levels of E2 were determined in individuals in the third trimester of pregnancy and at 1 week postpartum. A significant association was observed between E2 change and PPD susceptibility in the late postpartum period (6 weeks) [P = 0.002, odds ratio (OR) = 2.341, 95% confidence interval (CI) = 1.361-4.027], but it was not observed in the early postpartum period (1 week). There was no significant association between the 5-HTTLPR genotype and PPD risk at both the early and late postpartum periods (P > 0.05). However, the interaction between E2 change and the 5-HTTLPR polymorphism could reasonably influence PPD risk. The women who carried the SS genotype with large decreases in E2 showed a significantly higher risk for PPD at both the early (P = 0.002, OR = 2.525, 95% CI = 1.384-4.059) and late postpartum periods (P < 0.001, OR = 3.108, 95% CI = 1.562-4.436) compared with those who carried the SL/LL genotype. This study suggests that there is an association between E2 change in the perinatal period with the 5-HTTLPR genotype and the occurrence of PPD.

An alternative theory for hormone effects on sex differences in PTSD: The role of heightened sex hormones during trauma

Women are at least twice as susceptible to developing post-traumatic stress disorder (PTSD) compared to men. Although most research seeking to explain this discrepancy has focussed on the role of oestradiol during fear extinction learning, the role of progesterone has been overlooked, despite relatively consistent findings being reported concerning the role of progesterone during consolidation of emotional and intrusive memories. In this review article, we outline literature supporting the role of progesterone on memory formation, with particular emphasis on potential memory-enhancing properties of progesterone when subjects are placed under stress. It is possible that progesterone directly and indirectly exerts memory-enhancing effects at the time of trauma, which is an effect that may not be necessarily captured during non-stressful paradigms. We propose a model whereby progesterone's steroidogenic relationship to cortisol and brain-derived neurotrophic factor in combination with elevated oestradiol may enhance emotional memory consolidation during trauma and therefore present a specific vulnerability to PTSD formation in women, particularly during the mid-luteal phase of the menstrual cycle.

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.

DNA methylation from germline cells in veterans with PTSD

In this study we investigated genome-wide sperm DNA methylation patterns in trauma-exposed Vietnam veterans. At the genome-wide level, we identified 3 CpG sites associated with PTSD in sperm including two intergenic and one CpG within the CCDC88C gene. Of those associated with PTSD in sperm at a nominal level, 1868 CpGs were also associated with PTSD in peripheral blood (5.6% overlap) including the RORA, CRHR1 and DOCK2 genes that have been previously implicated in PTSD. A total of 10 CpG sites were significantly associated with a reported history of a diagnosed mental health condition in children and reached genome-wide significance. CpGs associated with a history of a reported mental health condition in children were also enriched (90% of tested genes) for genes previously reported to be resistant to demethylation, making them strong candidates for transgenerational inheritance. In conclusion, our findings identify a unique sperm-specific DNA methylation pattern that is associated with PTSD.

Genome-wide gene expression in a pharmacological hormonal transition model and its relation to depressive symptoms

OBJECTIVES

Sensitivity to sex-steroid hormone fluctuations may increase risk for perinatal depression. We aimed to identify genome-wide biological profiles in women demonstrating sensitivity to pharmacological sex-hormone manipulation with gonadotrophin-releasing hormone agonist (GnRHa).

METHODS

Longitudinal gene expression (Illumina Human HT12.v4) and DNA methylation data (Infinium HumanMethylation450K BeadChip) from 60 women (30 GnRHa, 30 placebo) were generated (Trial ID: NCT02661789). Differences between baseline and two follow-up points (initial stimulation- and subsequent early suppression phase) in the biphasic ovarian hormone response to GnRHa were assessed using linear mixed effects models.

RESULTS

Genome-wide analysis revealed 588 probes differentially expressed from GnRHa intervention to first stimulatory phase follow-up (intervention group × time) after 10% fdr multiple testing correction. Of these, 54% genes were also significantly associated with estradiol changes over time (proxy for GnRHa response magnitude), 9.5% were associated with changes in depressive symptoms, and 38% were associated with changes in neocortical serotonin transporter binding. The genes were implicated in TGF beta signaling, adipogenesis, regulation of actin cytoskeleton, and focal adhesion pathways and enriched for DNA methylation changes (P = 0.006).

CONCLUSIONS

These findings point toward an altered peripheral blood transcriptomic landscape in a pharmacological model of sex-hormone-induced depressive symptoms.

Working memory reflects vulnerability to early life adversity as a risk factor for substance use disorder in the FKBP5 cortisol cochaperone polymorphism, rs9296158

Early life adversity (ELA) negatively affects health behaviors in adulthood, but pathways from ELA exposure to behavioral outcomes are poorly understood. ELA in childhood and adolescence may translate into adult outcomes by way of modified glucocorticoid signaling. The cortisol cotransporter, FKBP5 has a G-to-A substitution (rs9296158) that hinders cortisol trafficking within target cells, and this impaired glucocorticoid signaling may shape the long-term response to ELA. We used performance on the Stroop test to assess working memory in 546 healthy young adults who had experienced 0, 1, or > 1 forms of ELA in childhood and adolescence and were genotyped for the FKBP5 rs9296158 G-to-A polymorphism. We observed a robust Gene x Environment interaction (F = 9.49, p < .0001) in which increased ELA exposure led to progressively greater Stroop interference in persons carrying AG and AA genotypes of FKBP5 with no such effect in GG carriers. Further work is needed to explore the modification of cognitive function resulting from ELA. Impairments in working memory illustrate how ELA may use glucocorticoid pathways to influence working memory with potential implications for decision-making and risky behavior including substance use disorders.

Methyl-CpG binding protein 2 functional alterations provide vulnerability to develop behavioral and molecular features of post-traumatic stress disorder in male mice

Post-traumatic stress disorder (PTSD) is a mental disorder characterized by symptoms of persistent anxiety arising after exposure to traumatic events. Stress susceptibility due to a complex interplay between genetic and environmental factors plays a major role in the disease etiology, although biological underpinnings have not been clarified. We hypothesized that aberrant functionality of the methyl-CpG binding protein 2 (MECP2), a master regulator of experience-dependent epigenetic programming, confers susceptibility to develop PTSD-like symptomatology in the aftermath of traumatic events. Transgenic male mice expressing a truncated form of MeCP2 protein (MeCP2-308) were exposed at adulthood to a trauma in the form of high-intensity footshocks. The presence and duration of PTSD-like symptoms were assessed and compared to those of trauma-exposed wild type littermates and MeCP2-308 mice subjected to a mild stressor. The effects of fluoxetine, a prime pharmacological PTSD treatment, on PTSD-like symptomatology were also explored. Trauma-exposed MeCP2-308 mice showed long-lasting hyperresponsiveness to both correct and incorrect predictors of the trauma and persistent increased avoidance of trauma-related cues. Traumatized MeCP2-308 mice also displayed abnormal post-traumatic plasma levels of the stress hormone corticosterone and altered peripheral gene expression mirroring that of PTSD patients. Fluoxetine improved PTSD-like symptoms in trauma-exposed MeCP2-308 mice. These findings provide evidence that MeCP2 dysfunction results in increased susceptibility to develop PTSD-like symptoms after trauma exposure, and identify trauma-exposed MeCP2-308 mice as a new tool to investigate the underpinnings of PTSD vulnerability.

MicroRNAs in Post-traumatic Stress Disorder

Post-traumatic stress disorder (PTSD) is a psychiatric disorder that can develop following exposure to or witnessing of a (potentially) threatening event. A critical issue is to pinpoint the (neuro)biological mechanisms underlying the susceptibility to stress-related disorder such as PTSD, which develops in the minority of ~15% of individuals exposed to trauma. Over the last few years, a first wave of epigenetic studies has been performed in an attempt to identify the molecular underpinnings of the long-lasting behavioral and mental effects of trauma exposure. The potential roles of non-coding RNAs (ncRNAs) such as microRNAs (miRNAs) in moderating or mediating the impact of severe stress and trauma are increasingly gaining attention. To date, most studies focusing on the roles of miRNAs in PTSD have, however, been completed in animals, using cross-sectional study designs and focusing almost exclusively on subjects with susceptible phenotypes. Therefore, there is a strong need for new research comprising translational and cross-species approaches that use longitudinal designs for studying trajectories of change contrasting susceptible and resilient subjects. The present review offers a comprehensive overview of available studies of miRNAs in PTSD and discusses the current challenges, pitfalls, and future perspectives of this field.

Allele-specific DNA methylation level of FKBP5 is associated with post-traumatic stress disorder

BACKGROUND

FK506-binding protein 5 (FKBP5) binds to glucocorticoid receptors and modulates glucocorticoid sensitivity. The FKBP5 gene has been implicated in the dysregulation of human stress responses, contributing to the risk and treatment response of stress-related disorders. The present study examined whether epigenetic changes in FKBP5 are associated with chronic post-traumatic stress disorder (PTSD) status in the context of FKBP5 genetic variation (rs1360780 polymorphism) among male veterans exposed to combat trauma.

METHODS

Korean male veterans who served on active duty during the Vietnam War were categorized into 2 groups: with PTSD (n = 123) and without PTSD (n = 116). The genotype of FKBP5 rs1360780 and DNA methylation levels of two CpG sites at the FKBP5 intron 7 region were assessed in peripheral blood. Analysis of covariance was performed to examine main and interaction effects of PTSD status and FKBP5 genotype on FKBP5 DNA methylation level, with age, trauma levels, and alcohol use as covariates.

RESULTS

A significant main effect of FKBP5 rs1360780 and PTSD and an interaction effect between genotype and PTSD status were found on mean FKBP5 DNA methylation level. The T allele of rs1360780 was associated with lower FKBP5 methylation level. In addition, the PTSD group showed significantly higher methylation than did the non-PTSD group among veterans carrying the risk T allele (n = 96), while no group difference was observed on methylation levels among veterans with the CC genotype (n = 143). Among veterans carrying the T allele, FKBP5 methylation levels were positively correlated with the severity of PTSD symptoms.

CONCLUSIONS

The present study demonstrated different FKBP5 methylation levels in PTSD depending on FKBP5 genetic variation among veterans exposed to combat trauma. The present finding suggests that the genetic and epigenetic modulation of FKBP5 is involved in the pathophysiology of PTSD. Further longitudinal research involving people exposed to trauma is required to understand causal relationships of FKBP5 in the development and recovery of PTSD.

Single prolonged stress PTSD model triggers progressive severity of anxiety, altered gene expression in locus coeruleus and hypothalamus and effected sensitivity to NPY

PTSD is heterogeneous disorder that can be long lasting and often has delayed onset following exposure to a traumatic event. Therefore, it is important to take a staging approach to evaluate progression of biological mechanisms of the disease. Here, we begin to evaluate the temporal trajectory of changes following exposure to traumatic stressors in the SPS rat PTSD model. The percent of animals displaying severe anxiety on EPM increased from 17.5% at one week to 57.1% two weeks after SPS stressors, indicating delayed onset or progressive worsening of the symptoms. The LC displayed prolonged activation, and dysbalance of the CRH/NPY systems, with enhanced CRHR1 gene expression, coupled with reduced mRNAs for NPY and Y2R. In the mediobasal hypothalamus, increased CRH mRNA levels were sustained, but there was a flip in alterations of HPA regulatory molecules, GR and FKBP5 and Y5 receptor at two weeks compared to one week. Two weeks after SPS, intranasal NPY at 300 µg/rat, but not 150 µg which was effective after one week, reversed SPS triggered elevated anxiety. It also reversed SPS elicited depressive/despair symptoms and hyperarousal. Overall, the results reveal time-dependent progression in development of anxiety symptoms and molecular impairments in gene expression for CRH and NPY systems in LC and mediobasal hypothalamus by SPS. With longer time afterwards only a higher dose of NPY was effective in reversing behavioral impairments triggered by SPS, indicating that therapeutic approaches should be adjusted according to the degree of biological progression of the disorder.

Inflammation and post-traumatic stress disorder

While post-traumatic stress disorder (PTSD) is currently diagnosed based solely on classic psychological and behavioral symptoms, a growing body of evidence has highlighted a link between this disorder and alterations in the immune and inflammatory systems. Epidemiological studies have demonstrated that PTSD is associated with significantly increased rates of physical comorbidities in which immune dysregulation is involved, such as metabolic syndrome, atherosclerotic cardiovascular disease, and autoimmune diseases. In line with this, a number of blood biomarker studies have reported that compared to healthy controls, individuals with PTSD exhibit significantly elevated levels of proinflammatory markers, such as interleukin-1β, interleukin-6, tumor necrosis factor-α, and C-reactive protein. Moreover, various lines of animal and human research have suggested that inflammation is not only associated with PTSD but also can play an important role in its pathogenesis and pathophysiology. In this review, we first summarize evidence suggestive of increased inflammation in PTSD. We then examine findings that suggest possible mechanisms of inflammation in this disorder in terms of two different but interrelated perspectives: putative causes of increased proinflammatory activities and potential consequences that inflammation generates. Given that there is currently a dearth of treatment options for PTSD, possibilities of new therapeutic approaches using pharmacological and non-pharmacological treatments/interventions that have anti-inflammatory effects are also discussed. Despite the increasing attention given to the inflammatory pathology of PTSD, there remains much to be elucidated, including more detailed mechanisms of inflammation, potential usefulness of inflammatory biomarkers as diagnostic and prognostic markers, and efficacy of novel treatment strategies targeting inflammation.

Region- and time-dependent gene regulation in the amygdala and anterior cingulate cortex of a PTSD-like mouse model

Posttraumatic stress disorder is developed by exposure to a threatening and/or a horrifying event and characterized by the presence of anxiety, hyperarousal, avoidance, and sleep abnormality for a prolonged period of time. To elucidate the potential molecular mechanisms, we constructed a mouse model by electric foot shock followed by situational reminders and performed transcriptome analysis in brain tissues. The stressed mice acquired anxiety-like behavior after 2 weeks and exaggerated startle response after 4 weeks. Avoidance latency and freezing behavior were sustained up to 5 weeks post stress and abnormal static behavior was observed during the sleep period. RNA sequencing was performed in two of the emotional regulatory regions, anterior cingulate cortex and amygdala, at 2 and 5 weeks post stress. More than 1000 differentially expressed genes were identified at 2 weeks in both regions. The number of the regulated genes remained constant in amygdala at 5 weeks post stress, whereas those in anterior cingulate cortex were plummeted. Although synaptic remodeling and endocrine system were the most enriched signaling pathways in both anterior cingulate cortex and amygdala, the individual gene expression profile was regulated in a region- and time-dependent manner. In addition, several genes associated with PTSD involved in Hypothalamic-Pituitary-Adrenal axis were differentially regulated. These findings suggested that global gene expression profile was dynamically regulated in accordance with the disease development stage, and therefore targeting the distinct signaling molecules in different region and development stage might be critical for effective treatment to PTSD.

Glucocorticoids and Hippocampal Structure and Function in PTSD

This review examines the putative link between glucocorticoid and hippocampal abnormalities in posttraumatic stress disorder (PTSD). Increased glucocorticoid receptor (GR) sensitivity in PTSD may permit enhanced negative feedback inhibition of cortisol at the pituitary, hypothalamus, or other brain regions comprising the hypothalamic-pituitary-adrenal (HPA) axis and would be expected to affect other physiological systems that are regulated by glucocorticoids. Molecular and transcriptional studies of cortisol are consistent with the hypothesis that cortisol actions may be amplified in PTSD as a result of enhanced GR sensitivity in monocytes and some brain regions, although cortisol levels themselves are unchanged and oftentimes lower than normal. Concurrently, magnetic resonance imaging studies have demonstrated that individuals with PTSD have smaller hippocampal volume than individuals without PTSD. Initial hypotheses regarding the mechanism underlying hippocampal alterations in PTSD focused on elevated glucocorticoid levels in combination with extreme stress as the primary cause, but this explanation has not been well supported in human studies. Lack of data from neuroimaging studies preclude a firm link between PTSD onset and hippocampal volume changes. Rather, the available evidence is consistent with the possibility that smaller hippocampal volume (like reduced cortisol levels and enhanced GR sensitivity) may be a vulnerability factor for developing the disorder; limitations of hippocampal-based models of PTSD are described. We further review neuroimaging studies examining hippocampal structure and function following manipulation of glucocorticoid levels and also examining changes in the hippocampus in relationship to other brain regions. Evidence that the GR may be an important therapeutic target for the treatment of PTSD, especially for functions subserved by the hippocampus, is discussed. Implications of the current review for future research are described, with an emphasis on the need to integrate findings of glucocorticoid abnormalities with functional-imaging paradigms to formulate a comprehensive model of HPA-axis functioning in PTSD.

DNA methylation correlates of PTSD: Recent findings and technical challenges

There is increasing evidence that epigenetic factors play a critical role in posttraumatic stress disorder (PTSD), by mediating the impact of environmental exposures to trauma on the regulation of gene expression. DNA methylation is one epigenetic process that has been highly studied in PTSD. This review will begin by providing an overview of DNA methylation (DNAm) methods, and will then highlight two major biological systems that have been identified in the epigenetic regulation in PTSD: (a) the immune system and (b) the stress response system. In addition to candidate gene approaches, we will review novel strategies to study epigenome-wide PTSD-related effects, including epigenome-wide algorithms that distill information from many loci into a single summary score (e.g., measures of "epigenetic age" which have been associated with PTSD). This review will also cover recent epigenome wide association studies (EWAS) of PTSD, and biological pathway models used to identify gene sets enriched in PTSD. Finally, we address technical and methodological advances and challenges to the field, and highlight exciting directions for future research.

Glucocorticoid-induced enhancement of extinction-from animal models to clinical trials

Extensive evidence from both animal model and human research indicates that glucocorticoid hormones are crucially involved in modulating memory performance. Glucocorticoids, which are released during stressful or emotionally arousing experiences, enhance the consolidation of new memories, including extinction memory, but reduce the retrieval of previously stored memories. These memory-modulating properties of glucocorticoids have recently received considerable interest for translational purposes because strong aversive memories lie at the core of several fear-related disorders, including post-traumatic stress disorder and phobias. Moreover, exposure-based psychological treatment of these disorders relies on successful fear extinction. In this review, we argue that glucocorticoid-based interventions facilitate fear extinction by reducing the retrieval of aversive memories and enhancing the consolidation of extinction memories. Several clinical trials have already indicated that glucocorticoids might be indeed helpful in the treatment of fear-related disorders.

Animal models of PTSD: a challenge to be met

Recent years have seen increased interest in psychopathologies related to trauma exposure. Specifically, there has been a growing awareness to posttraumatic stress disorder (PTSD) in part due to terrorism, climate change-associated natural disasters, the global refugee crisis, and increased violence in overpopulated urban areas. However, notwithstanding the increased awareness to the disorder, the increasing number of patients, and the devastating impact on the lives of patients and their families, the efficacy of available treatments remains limited and highly unsatisfactory. A major scientific effort is therefore devoted to unravel the neural mechanisms underlying PTSD with the aim of paving the way to developing novel or improved treatment approaches and drugs to treat PTSD. One of the major scientific tools used to gain insight into understanding physiological and neuronal mechanisms underlying diseases and for treatment development is the use of animal models of human diseases. While much progress has been made using these models in understanding mechanisms of conditioned fear and fear memory, the gained knowledge has not yet led to better treatment options for PTSD patients. This poor translational outcome has already led some scientists and pharmaceutical companies, who do not in general hold opinions against animal models, to propose that those models should be abandoned. Here, we critically examine aspects of animal models of PTSD that may have contributed to the relative lack of translatability, including the focus on the exposure to trauma, overlooking individual and sex differences, and the contribution of risk factors. Based on findings from recent years, we propose research-based modifications that we believe are required in order to overcome some of the shortcomings of previous practice. These modifications include the usage of animal models of PTSD which incorporate risk factors and of the behavioral profiling analysis of individuals in a sample. These modifications are aimed to address factors such as individual predisposition and resilience, thus taking into consideration the fact that only a fraction of individuals exposed to trauma develop PTSD. We suggest that with an appropriate shift of practice, animal models are not only a valuable tool to enhance our understanding of fear and memory processes, but could serve as effective platforms for understanding PTSD, for PTSD drug development and drug testing.

Cumulative influence of parity-related genomic changes in multiple sclerosis

Pregnancy reduces the frequency of relapses in Multiple Sclerosis (MS) and parity also has a beneficial long term effect on disease outcome. We aimed to uncover the biological mechanisms underlying the beneficial long-term effects of parity in MS. Genome-wide gene expression revealed 574 genes associated with parity; 38.3% showed significant DNA methylation changes (enrichment p = 0.029). These genes overlapped with previous MS genes in humans and a rat MS model and were overrepresented within axon guidance (P = 1.6e-05), developmental biology (P = 0.0094) and cell-cell communication (P = 0.019) pathways. This gene regulation could provide a basis for a protective effect of parity on the long-term outcome of MS.

Association of rs1042522 SNP with Clinicopathologic Factors of Breast Cancer Patients in the Markazi Province of Iran

BACKGROUND:

The nucleotide changes in different genetic loci increased the incidence risk of breast cancer.

AIM:

The aim of present study was to investigate genotype distribution at codon 72 of the TP53 gene (rs1042522) in breast cancer patients to achieve a potential diagnostic marker related to some demographic feathers.

METHODS:

In our case-control study, blood samples were collected from a total of 34 patients harboured breast cancer. DNA was extracted, and nested-PCR was performed. Products were digested with AccII and subsequently were sequenced. Results were compared with samples characteristics.

RESULTS:

The PCR results indicated the correct implementation of extraction and amplification protocol. The genotypic distribution at codon 72 of TP53 in control group was 20%, 62.4% and 16.6% for Arg (wildtype), Arg/Pro (heterozygous) and Pro (homozygous variant) respectively. Also, this distribution in the patient group was 23.52% homozygous, 50% heterozygous, and 26.47% another homozygous variant (Adjusted odds ratio: 1.12 and 95%CI = 0.57 to 2.2, P = 0.03). The absence of Arg at codon 72 of TP53 is relevant with age higher than 40 years and metastasis to other organs.

CONCLUSION:

Polymorphism at codon 72 of TP53 was associated with high-grades of breast cancer risk and different responses to chemotherapy treatment. It is recommended genotype distribution of codon 72 of TP53 before chemotherapy.

Precision pharmacotherapy: psychiatry's future direction in preventing, diagnosing, and treating mental disorders

Mental disorders account for around one-third of disability worldwide and cause enormous personal and societal burden. Current pharmacotherapies and nonpharmacotherapies do help many patients, but there are still high rates of partial or no response, delayed effect, and unfavorable adverse effects. The current diagnostic taxonomy of mental disorders by the Diagnostic and Statistical Manual of Mental Disorders and the International Classification of Diseases relies on presenting signs and symptoms, but does not reflect evidence from neurobiological and behavioral systems. However, in the last decades, the understanding of biological mechanisms underlying mental disorders has grown and can be used for the development of precision medicine, that is, to deliver a patient-tailored individual treatment. Precision medicine may incorporate genetic variants contributing to the mental disorder and the response to pharmacotherapies, but also consider gene ¥ environment interactions, blood-based markers, neuropsychological tests, data from electronic health records, early life adversity, stressful life events, and very proximal factors such as lifestyle, nutrition, and sport. Methods such as artificial intelligence and the underlying machine learning and deep learning approaches provide the framework to stratify patients, initiate specific tailored treatments and thus increase response rates, reduce adverse effects and medical errors. In conclusion, precision medicine uses measurable health parameters to identify individuals at risk of a mental disorder, to improve the diagnostic process and to deliver a patient-tailored treatment.

Transcriptome analysis reveals novel genes and immune networks dysregulated in veterans with PTSD

BACKGROUND

Posttraumatic stress disorder (PTSD) is a serious condition that emerges following trauma exposure and involves long-lasting psychological suffering and health-issues. Uncovering critical genes and molecular networks is essential to understanding the biology of the disorder. We performed a genome-wide scan to identify transcriptome signatures of PTSD.

METHODS

Genome-wide peripheral blood transcriptomic data from 380 service personnel were investigated. This included a discovery sample of 96 Australian Vietnam War veterans and two independent pre and post-deployment replication samples of U.S. Marines (N = 188 and N = 96).

RESULTS

A total of 60 transcripts were differentially expressed between veterans with and without PTSD, surviving Bonferroni multiple testing correction. Genes within the cytokine-cytokine receptor interaction, Jak-STAT signaling and Toll-like receptor signaling pathways were enriched. For 49% of the genes, gene expression changes were also accompanied by DNA methylation changes. Using replication data from two U.S. Marine cohorts, we observed that of the differentially expressed genes, 71% genes also showed significant gene expression changes between pre and post-deployment. Weighted gene co-expression networks revealed two modules of genes associated with PTSD. The first module (67 genes, p-value = 6e-4) was enriched for genes within the 11p13 locus including BDNF. The second module (266 genes, p-value = 0.01) was enriched for genes in 17q11 including SLC6A4, STAT5A and STAT5B.

CONCLUSIONS

We identified novel transcriptomic loci and biological pathways for PTSD in service personnel. Network analysis revealed enrichment of loci harboring key candidate genes in PTSD. These findings highlight the role of transcriptional biomarkers in the molecular etiology of PTSD.

Problematic alcohol use associates with sodium channel and clathrin linker 1 (SCLT1) in trauma-exposed populations

Excessive alcohol use is extremely prevalent in the United States, particularly among trauma-exposed individuals. While several studies have examined genetic influences on alcohol use and related problems, this has not been studied in the context of trauma-exposed populations. We report results from a genome-wide association study of alcohol consumption and associated problems as measured by the alcohol use disorders identification test (AUDIT) in a trauma-exposed cohort. Results indicate a genome-wide significant association between total AUDIT score and rs1433375 [N = 1036, P = 2.61 × 10^-8 (dominant model), P = 7.76 × 10^-8 (additive model)], an intergenic single-nucleotide polymorphism located 323 kb upstream of the sodium channel and clathrin linker 1 (SCLT1) at 4q28. rs1433375 was also significant in a meta-analysis of two similar, but independent, cohorts (N = 1394, P = 0.0004), the Marine Resiliency Study and Systems Biology PTSD Biomarkers Consortium. Functional analysis indicated that rs1433375 was associated with SCLT1 gene expression and cortical-cerebellar functional connectivity measured via resting state functional magnetic resonance imaging. Together, findings suggest a role for sodium channel regulation and cerebellar functioning in alcohol use behavior. Identifying mechanisms underlying risk for problematic alcohol use in trauma-exposed populations is critical for future treatment and prevention efforts.

Targeting the FKBP51/GR/Hsp90 Complex to Identify Functionally Relevant Treatments for Depression and PTSD

Genetic and epigenetic alterations in FK506-binding protein 5 ( FKBP5) have been associated with increased risk for psychiatric disorders, including post-traumatic stress disorder (PTSD). Some of these common variants can increase the expression of FKBP5, the gene that encodes FKBP51. Excess FKBP51 promotes hypothalamic-pituitary-adrenal (HPA) axis dysregulation through altered glucocorticoid receptor (GR) signaling. Thus, we hypothesized that GR activity could be restored by perturbing FKBP51. Here, we screened 1280 pharmacologically active compounds and identified three compounds that rescued FKBP51-mediated suppression of GR activity without directly activating GR. One of the three compounds, benztropine mesylate, disrupted the association of FKBP51 with the GR/Hsp90 complex in vitro. Moreover, we show that removal of FKBP51 from this complex by benztropine restored GR localization in ex vivo brain slices and primary neurons from mice. In conclusion, we have identified a novel disruptor of the FKBP51/GR/Hsp90 complex. Targeting this complex may be a viable approach to developing treatments for disorders related to aberrant FKBP51 expression.

Hsp90 and FKBP51: complex regulators of psychiatric diseases

Mood disorders affect nearly a quarter of the world's population. Therefore, understanding the molecular mechanisms underlying these conditions is of great importance. FK-506 binding protein 5 (FKBP5) encodes the FKBP51 protein, a heat shock protein 90 kDa (Hsp90) co-chaperone, and is a risk factor for several affective disorders. FKBP51, in coordination with Hsp90, regulates glucocorticoid receptor (GR) activity via a short negative feedback loop. This signalling pathway rapidly restores homeostasis in the hypothalamic-pituitary-adrenal (HPA) axis following stress. Expression of FKBP5 increases with age through reduced DNA methylation. High levels of FKBP51 are linked to GR resistance and reduced stress coping behaviour. Moreover, common allelic variants in the FKBP5 gene are associated with increased risk of developing affective disorders like anxiety, depression and post-traumatic stress disorder (PTSD). This review highlights the current understanding of the Hsp90 co-chaperone, FKBP5, in disease from both human and animal studies. In addition, FKBP5 genetic implications in the clinic involving life stress exposure, gender differences and treatment outcomes are discussed.This article is part of the theme issue 'Heat shock proteins as modulators and therapeutic targets of chronic disease: an integrated perspective'.

Transcriptome Alterations in Posttraumatic Stress Disorder

Posttraumatic stress disorder (PTSD) is a debilitating psychiatric disorder with a lifetime prevalence of nearly 8% in the general population. While the underlying molecular and cellular mechanisms of PTSD remain unknown, recent studies indicate that PTSD is associated with aberrant gene expression in brain as well as peripheral blood cells. The advent of next-generation sequencing technologies will allow us to elucidate the gene expression changes occurring in both brain and blood of patients with PTSD. RNA sequencing allows for analysis of the amount of transcript being made as well as alternative splicing, novel transcript identification, microRNA, and noncoding RNA quantification. Here we provide an overview of the different types of transcriptomic technologies as well as the gene expression studies performed in human peripheral blood and animal models of PTSD, and review the human PTSD postmortem brain gene profiling studies performed to date.

Neurogenetic Approaches to Stress and Fear in Humans as Pathophysiological Mechanisms for Posttraumatic Stress Disorder

In this review article, genetic variation associated with brain responses related to acute and chronic stress reactivity and fear learning in humans is presented as an important mechanism underlying posttraumatic stress disorder. We report that genes related to the regulation of the hypothalamic-pituitary-adrenal axis, as well as genes that modulate serotonergic, dopaminergic, and neuropeptidergic functions or plasticity, play a role in this context. The strong overlap of the genetic targets involved in stress and fear learning suggests that a dimensional and mechanistic model of the development of posttraumatic stress disorder based on these constructs is promising. Genome-wide genetic analyses on fear and stress mechanisms are scarce. So far, reliable replication is still lacking for most of the molecular genetic findings, and the proportion of explained variance is rather small. Further analysis of neurogenetic stress and fear learning needs to integrate data from animal and human studies.

How to measure glucocorticoid receptor's sensitivity in patients with stress-related psychiatric disorders

Stress is a state of derailed homeostasis and a main environmental risk factor for psychiatric diseases. Chronic or uncontrollable stress may lead to a dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, which is a common feature of stress-related psychiatric disorders. One of the key mechanisms underlying a disturbed HPA axis is an impaired function of the glucocorticoid receptor (GR) with an enhanced or reduced feedback sensitivity for glucocorticoids and subsequently altered concentrations of peripheral cortisol. GR function is regulated by a multiprotein complex including the different expression of the hsp90 co-chaperone FK 506 binding protein 51 (FKBP5) that may be genetically determined or acquired in response to stressful stimuli. Specific patterns of a dysregulation of the HPA axis and GR function are found in different stress-related psychiatric entities e.g. major depression, job-related exhaustion or posttraumatic stress disorder. GR challenge tests like the dexamethasone-suppression test (DST), the dexamethasone-corticotropin-releasing hormone (dex-CRH) test or most recently the analysis of the dexamethasone-induced gene expression are employed to sensitively measure HPA axis activity in these disorders. They provide information for a stratification of phenotypic similar but neurobiological diverse psychiatric disorders. In this review we present a synopsis of GR challenge tests with a focus on the application of the DST, the CRH test and the dex-CRH test as well as the dexamethasone-induced gene expression in stress-related psychiatric entities.

Recent Genetics and Epigenetics Approaches to PTSD

PURPOSE OF REVIEW

Following a life-threatening traumatic exposure, about 10% of those exposed are at considerable risk for developing posttraumatic stress disorder (PTSD), a severe and disabling syndrome characterized by uncontrollable intrusive memories, nightmares, avoidance behaviors, and hyperarousal in addition to impaired cognition and negative emotion symptoms. This review will explore recent genetic and epigenetic approaches to PTSD that explain some of the differential risk following trauma exposure.

RECENT FINDINGS

A substantial portion of the variance explaining differential risk responses to trauma exposure may be explained by differential inherited and acquired genetic and epigenetic risk. This biological risk is complemented by alterations in the functional regulation of genes via environmentally induced epigenetic changes, including prior childhood and adult trauma exposure. This review will cover recent findings from large-scale genome-wide association studies as well as newer epigenome-wide studies. We will also discuss future "phenome-wide" studies utilizing electronic medical records as well as targeted genetic studies focusing on mechanistic ways in which specific genetic or epigenetic alterations regulate the biological risk for PTSD.

A Clinician's Guide to PTSD Biomarkers and Their Potential Future Use

No clinically validated biomarkers have yet been found to assist in the diagnosis and treatment of posttraumatic stress disorder (PTSD). Innovation in clinical trial design, however, has led to the study of biomarkers as part of testing new medications and psychotherapies. There may soon be viable biomarkers to assist in diagnosis of PTSD and prediction of illness trajectory, severity, and functional outcomes; subtyping; and treatment selection. Processes for the identification and validation of biomarker findings are complex, involving several stages of clinical testing before use. The authors provide an overview of issues regarding the clinical use of PTSD biomarkers and examine a set of genetic, epigenetic, and other blood-based markers along with physiological markers currently proposed as candidate tests for PTSD. Studies that have identified candidate biomarkers with relevance to treatment selection in PTSD are discussed as a promising area of research that may lead to changes in clinical practice.