FKBP5 polymorphisms and hypothalamic-pituitary-adrenal axis negative feedback in major depression and obsessive-compulsive disorder

The Role of HSP90 Molecular Chaperones in Depression: Potential Mechanisms

Major depressive disorder (MDD) is characterized by high rates of disability and death and has become a public health problem that threatens human life and health worldwide. HPA axis disorder and neuroinflammation are two common biological abnormalities in MDD patients. Hsp90 is an important molecular chaperone that is widely distributed in the organism. Hsp90 binds to the co-chaperone and goes through a molecular chaperone cycle to complete its regulation of the client protein. Numerous studies have demonstrated that Hsp90 regulates how the HPA axis reacts to stress and how GR, the HPA axis' responsive substrate, matures. In addition, Hsp90 exhibits pro-inflammatory effects that are closely related to neuroinflammation in MDD. Currently, Hsp90 inhibitors have made some progress in the treatment of a variety of human diseases, but they still need to be improved. Further insight into the role of Hsp90 in MDD provides new ideas for the development of new antidepressant drugs targeting Hsp90.

Downregulation of FKBP5 Promotes Atrial Arrhythmogenesis

BACKGROUND

Atrial fibrillation (AF), the most common arrhythmia, is associated with the downregulation of FKBP5 (encoding FKBP5 [FK506 binding protein 5]). However, the function of FKBP5 in the heart remains unknown. Here, we elucidate the consequences of cardiomyocyte-restricted loss of FKBP5 on cardiac function and AF development and study the underlying mechanisms.

METHODS

Right atrial samples from patients with AF were used to assess the protein levels of FKBP5. A cardiomyocyte-specific FKBP5 knockdown mouse model was established by crossbreeding Fkbp5flox/flox mice with Myh6MerCreMer/+ mice. Cardiac function and AF inducibility were assessed by echocardiography and programmed intracardiac stimulation. Histology, optical mapping, cellular electrophysiology, and biochemistry were employed to elucidate the proarrhythmic mechanisms due to loss of cardiomyocyte FKBP5.

RESULTS

FKBP5 protein levels were lower in the atrial lysates of patients with paroxysmal AF or long-lasting persistent (chronic) AF. Cardiomyocyte-specific knockdown mice exhibited increased AF inducibility and duration compared with control mice. Enhanced AF susceptibility in cardiomyocyte-specific knockdown mice was associated with the development of action potential alternans and spontaneous Ca2+ waves, and increased protein levels and activity of the NCX1 (Na+/Ca2+-exchanger 1), mimicking the cellular phenotype of chronic AF patients. FKBP5-deficiency enhanced transcription of Slc8a1 (encoding NCX1) via transcription factor hypoxia-inducible factor 1α. In vitro studies revealed that FKBP5 negatively modulated the protein levels of hypoxia-inducible factor 1α by competitively interacting with heat-shock protein 90. Injections of the heat-shock protein 90 inhibitor 17-AAG normalized protein levels of hypoxia-inducible factor 1α and NCX1 and reduced AF susceptibility in cardiomyocyte-specific knockdown mice. Furthermore, the atrial cardiomyocyte-selective knockdown of FKBP5 was sufficient to enhance AF arrhythmogenesis.

CONCLUSIONS

This is the first study to demonstrate a role for the FKBP5-deficiency in atrial arrhythmogenesis and to establish FKBP5 as a negative regulator of hypoxia-inducible factor 1α in cardiomyocytes. Our results identify a potential molecular mechanism for the proarrhythmic NCX1 upregulation in chronic AF patients.

Role of FKBP5 and its genetic mutations in stress-induced psychiatric disorders: an opportunity for drug discovery

Stress-induced mental health disorders are affecting many people around the world. However, effective drug therapy for curing psychiatric diseases does not occur sufficiently. Many neurotransmitters, hormones, and mechanisms are essential in regulating the body's stress response. One of the most critical components of the stress response system is the hypothalamus-pituitary-adrenal (HPA) axis. The FKBP prolyl isomerase 51 (FKBP51) protein is one of the main negative regulators of the HPA axis. FKBP51 negatively regulates the cortisol effects (the end product of the HPA axis) by inhibiting the interaction between glucocorticoid receptors (GRs) and cortisol, causing reduced transcription of downstream cortisol molecules. By regulating cortisol effects, the FKBP51 protein can indirectly regulate the sensitivity of the HPA axis to stressors. Previous studies have indicated the influence of FKBP5 gene mutations and epigenetic changes in different psychiatric diseases and drug responses and recommended the FKBP51 protein as a drug target and a biomarker for psychological disorders. In this review, we attempted to discuss the effects of the FKBP5 gene, its mutations on different psychiatric diseases, and drugs affecting the FKBP5 gene.

Human myeloid progenitor glucocorticoid receptor activation causes genomic instability, type 1 IFN- response pathway activation and senescence in differentiated microglia; an early life stress model

One form of early life stress, prenatal exposure to glucocorticoids (GCs), confers a higher risk of psychiatric and neurodevelopmental disorders in later life. Increasingly, the importance of microglia in these disorders is recognized. Studies on GCs exposure during microglial development have been limited, and there are few, if any, human studies. We established an in vitro model of ELS by continuous pre-exposure of human iPS-microglia to GCs during primitive hematopoiesis (the critical stage of iPS-microglial differentiation) and then examined how this exposure affected the microglial phenotype as they differentiated and matured to microglia, using RNA-seq analyses and functional assays. The iPS-microglia predominantly expressed glucocorticoid receptors over mineralocorticoid receptors, and in particular, the GR-α splice variant. Chronic GCs exposure during primitive hematopoiesis was able to recapitulate in vivo ELS effects. Thus, pre-exposure to prolonged GCs resulted in increased type I interferon signaling, the presence of Cyclic GMP-AMP synthase-positive (cGAS) micronuclei, cellular senescence and reduced proliferation in the matured iPS-microglia. The findings from this in vitro ELS model have ramifications for the responses of microglia in the pathogenesis of GC- mediated ELS-associated disorders such as schizophrenia, attention-deficit hyperactivity disorder and autism spectrum disorder.

Psycho-cognitive assessment and quality of life in older adults with chronic obstructive pulmonary disease-carrying the rs4713916 gene polymorphism (G/A) of gene FKBP5 and response to pulmonary rehabilitation: a proof of concept study

PURPOSE

Chronic obstructive pulmonary disease (COPD) is characterized by pulmonary and extra-pulmonary multi-morbidity including depression, anxiety and cognitive disorders. Several studies investigated the association of the FKBP5 gene polymorphisms with susceptibility to anxiety, depression, and behavioral disorders. The FKBP5 gene codifies the FKBP51 protein which modulates the glucocorticoid receptor in the adaptive stress response. Genetic variants of the FKBP5 gene have been associated to a higher risk of developing mental disorders. We analyzed the association of genetic variants and stress exposure investigating the susceptibility to psychological distress and the impact on cognitive balance and quality of life (QoL) of COPD patients carrying the rs4713916 polymorphism (G/A) and we examined its association, with COPD rehabilitative outcomes.

MATERIALS AND METHODS

A pilot study evaluated cognitive, psychological, clinical alterations/disorders, QoL, and coping strategies in 70 older adults with COPD, undergoing pulmonary rehabilitation, stratified according to the FKBP5 rs4713916 genotype (GG or GA).

RESULTS

Carriers of rs4713916 polymorphisms (G/A) show better cognitive performances, a higher degree of independence in the daily living activities, better QoL, no presence of depressive mood and anxiety symptoms, no family history of psychiatric disorders, more ability to cope with stressors by avoiding emotions but demanding emotional support, and lesser use of anti-anxiety, anti-depressant, anti-psychotic, hypnotic-sedative drugs. No difference was found in the number of comorbidities.

CONCLUSION

These results offer valuable insights into the role of FKBP5 in the complex network of mechanisms associated to clinical, psychological and behavioral features of COPD patients.

Proteomics Study Reveals the Anti-Depressive Mechanisms and the Compatibility Advantage of Chaihu-Shugan-San in a Rat Model of Chronic Unpredictable Mild Stress

Background: Chaihu-Shugan-San is a classical prescription to treat depression. According to the traditional Chinese medicine (TCM) principle, the 2 decomposed recipes in Chaihu-Shugan-San exert synergistic effects, including Shu Gan (stagnated Gan-Qi dispersion) and Rou Gan (Gan nourishment to alleviate pain). However, the specific mechanism of Chaihu-Shugan-San on depression and its compatibility rule remain to be explored.

Objective: We aimed to explore the anti-depression mechanisms and analyze the advantage of TCM compatibility of Chaihu-Shugan-San.

Methods: The chronic unpredictable mild stress (CUMS) rat model was established. Antidepressant effects were evaluated by sucrose preference test (SPT), and forced swimming test (FST). Tandem Mass Tag (TMT)-based quantitative proteomics of the hippocampus was used to obtain differentially expressed proteins (DEPs). Bioinformatics analysis including Gene Ontology (GO), pathway enrichment, and protein-protein interaction (PPI) networks was utilized to study the DEPs connections. At last, the achieved key targets were verified by western blotting.

Results: Chaihu-Shugan-San increased weight gain and food intake, as well as exhibited better therapeutic effects including enhanced sucrose preference and extended immobility time when compared with its decomposed recipes. Proteomics showed Chaihu-Shugan-San, Shu Gan, and Rou Gan regulated 110, 12, and 407 DEPs, respectively. Compared with Shu Gan or Rou Gan alone, the expression of 22 proteins was additionally changed by Chaihu-Shugan-San treatment, whereas the expression of 323 proteins whose expression was changed by Shu Gan or Rou Gan alone were not changed by Chaihu-Shugan-San treatment. Bioinformatics analysis demonstrated that Chaihu-Shugan-San affected neurotransmitter’s release and transmission cycle (e.g., γ-aminobutyric acid (GABA), glutamate, serotonin, norepinephrine, dopamine, and acetylcholine). GABA release pathway is also targeted by the 22 DEPs. Unexpectedly, only 2 pathways were enriched by the 323 DEPs: Metabolism and Cellular responses to external stimuli. Lastly, the expression of Gad2, Vamp2, and Pde2a was verified by western blotting.

Conclusions: Chaihu-Shugan-San treats depression via multiple targets and pathways, which may include regulations of 110 DEPs and some neurotransmitter’s transmission cycle. Compared with Shu Gan and Rou Gan, the 22 Chaihu-Shugan-San advanced proteins and the affected GABA pathway may be the advantages of Chaihu-Shugan-San compatibility. This research offers data and theory support for the clinical application of Chaihu-Shugan-San.

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.

Polymorphisms in the FKBP5 gene are associated with attention deficit and hyperactivity disorder in Korean children

Attention deficit hyperactivity disorder (ADHD) is a common and heritable childhood psychiatric disorder. Recently, many studies reported a down-regulated hypothalamus-pituitary-adrenal axis (HPA-axis) with low cortisol levels in children with ADHD. The FK506 binding protein 5 or FKBP5 gene regulates the negative feedback of the HPA-axis, and genetic variants in this gene showed an association with ADHD. We investigated the genetic association between FKBP5 gene polymorphisms and susceptibility to ADHD in Korean children. We conducted a case-control study with 150 ADHD children and 322 controls. Genotyping of FKBP5 rs9394309 and rs7748266 was performed by using polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP). Our results showed that rs7748266 polymorphism has significant genotype (p = 0.021) and allele (p = 0.009) frequency differences between children with ADHD and the control group. CT genotype [odds ratio (OR) 1.70, 95 % confidence interval (CI) 1.134-2.540, p = 0.010] and T allele (OR 1.54, 95 % CI 1.114-2.117, p = 0.009) were associated with increased risk of ADHD. In addition, dominant (p = 0.006) and over-dominant genetic (p = 0.016) models showed significant associations with ADHD. In the stratified analysis, a significant result was obtained from the girl samples (p = 0.048). The OR of the girls with ADHD with CT genotype was 2.29 (95 % CI 1.170-4.469, p = 0.014). In contrast to rs7748266 polymorphism, rs9394309 polymorphism did not show any significant result (p > 0.05). Haplotype analysis also revealed a significant difference of the TG haplotype for rs7748266 - rs9394309 (p = 0.028, global haplotype association p-value of 0.0091). Conclusively, we confirmed that FKBP5 gene polymorphisms were associated with ADHD in Korean children. These results suggested that FKBP5 may factor in the development of ADHD.

The role of childhood trauma, HPA axis reactivity and FKBP5 genotype on cognition in healthy individuals

Cognitive impairment has been associated with both childhood adversity and abnormalities of hypothalamic-pituitary-adrenal (HPA) axis function. An interaction exists between the functional polymorphism rs1360780 in the FKBP5 gene and childhood maltreatment, influencing a variety of clinical outcomes. Our goal was to study the relationship between different types of childhood trauma, HPA axis functionality, rs1360780 genotype and cognitive function in 198 healthy individuals who participated in the study. We obtained clinical data, childhood maltreatment scores and neurocognitive performance by clinical assessment; HPA negative feedback was analysed using the dexamethasone suppression test ratio (DSTR) after administration of 0.25 mg of dexamethasone; and the FKBP5 rs1360780 polymorphism was genotyped in DNA obtained from blood samples. The results showed a significant influence of physical neglect on measures of neurocognition as well as an interaction between the DSTR and physical and emotional neglect. Regarding social cognition, a significant association was found with sexual and physical abuse as well as with rs1360780 risk-allele carrier status. Moreover, an interaction between the rs1360780 genotype and the presence of physical abuse was significantly associated with social cognition results. Our results suggest a specific impact of different kinds of childhood maltreatment on measures of neurocognition and social cognition, which might be influenced by HPA axis reactivity and genetic variants in HPA axis-related genes such as FKBP5. Disentangling the relationship between these elements and their influence on cognitive performance might help identify susceptible individuals with higher stress vulnerability and develop preventive interventions.

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.

Paeoniflorin ameliorates depressive-like behavior in prenatally stressed offspring by restoring the HPA axis- and glucocorticoid receptor- associated dysfunction

BACKGROUND

Prenatal stress (PS) can increase the risk of nervous, endocrine and metabolic diseases and induce depression in offspring. Paeoniflorin (PA) is an amorphous glucoside isolated from the aqueous extract of roots of the peony plant (Paeonia lactiflora Pall.) and exerts various pharmacological effects in the nervous system.

METHODS

Male prenatally stressed offspring were used to investigate the antidepression-like effects and possible mechanism of PA. We measured animal behavior, HPA axis, Nissil staining, and Ng expression. Additionally, we assessed the modulation of hippocampal glucocorticoid receptors (GR) nuclear translocation and SNARE complex expression by western blotting.

RESULTS

The results showed that administration of PA (15, 30, and 60 mg/kg/day, i.g.) for 28 days markedly increased sucrose intake and decreased the immobility time and the total number of crossings, center crossings, rearing, and grooming in male PS offspring. Moreover, PA significantly reduced the serum corticosterone (CORT), adrenocorticotropin (ACTH), corticotropin-releasing hormone (CRH) and hippocampal glutamate (Glu) levels in male PS offspring, which were stimulated by an increase of GR nuclear translocation. Furthermore, PA markedly increased neurogranin (Ng) protein expression in the hippocampus CA3 region in offspring. PA also markedly decreased hippocampal Glu by inhibiting SNAP25, VAMP2, Syntaxin1a and related protein expression; SNARE complex formation; and EAAT2/3, NR1, NR2A, and FKBP5 protein expression.

CONCLUSIONS

Taken together, the results of this study show that PA has antidepression-like effects in male PS offspring, partially due to the HPA axis, GR dysfunction and Glu transport system.

Hypothalamic-pituitary-adrenal axis-related genes and cognition in major mood disorders and schizophrenia: a systematic review

Hypothalamic-pituitary-adrenal (HPA) axis dysregulation and cognitive deficits are two well-characterized endophenotypes present in different serious mental illnesses (SMIs), including major depressive disorder, bipolar disorder and schizophrenia. Our aim was to study the influence of genetic and epigenetic variations in HPA axis-related genes on cognitive performance in clinical samples, including patients with major mood disorders and schizophrenia. A systematic search was performed using PubMed (Medline), PsycINFO and Scopus databases. The systematic review identified 12 studies dealing with HPA-related genes and cognition in samples including patients with SMIs, focusing on single nucleotide polymorphism (SNP) variants, while no studies analysing epigenetic variations were found. The results suggest different and specific effects on the cognitive performance of SNP variants in the HPA axis-related genes studied, as well as interactions with traumatic experiences. There was high heterogeneity in the studied samples, genes analysed, and cognitive tasks evaluated. The relationship between HPA-related genes and cognition in SMIs is still largely unknown, and further studies including larger samples and epigenetic variations are needed.

Association of FKBP5 polymorphisms with patient susceptibility to coronary artery disease comorbid with depression

BACKGROUND

Coronary artery disease (CAD) and depression cause great burden to society and frequently co-occur. The exact mechanisms of this comorbidity are unclear. FK506-binding protein 51 (FKBP51) is correlated with cardiovascular disease and depression. The aim of this study was to determine the role of the seven single nucleotide polymorphisms (SNPs) of FKBP5 that code FKBP51, namely, rs1360780 (C>T), rs2817032 (T>C), rs2817035 (G>A), rs9296158 (G>A), rs9470079 (G>A), rs4713902 (T>C), and rs3800373 (C>T) in a patient's susceptibility to comorbid CAD and depression.

METHODS

We enrolled 271 Northern Chinese Han patients with CAD, including 123 patients with depression and 147 patients without depression. We also included 113 healthy controls that match the patients' sex and age. Genomic DNA from whole blood was extracted, and seven SNPs were assessed using MassArray method. Patient Health Questionnaire-9 was applied to access the depression.

RESULTS

The GA genotype for rs9470079 was associated with a significantly decreased risk of CAD (odds ratio = 0.506, 95% confidence interval = 0.316-0.810, P = 0.005) when the GG genotype was used as reference. A statistically significant difference was observed among females but not among males in the rs9470079 genotype and allele frequency. Patients with CAD were further divided into CAD+D and CAD-D groups according to the presence of comorbid depression and were compared with the controls. Significant differences were found regarding the genotype and allele frequency of rs2817035 and rs9470079 in CAD+H groups compared with the control subjects in all groups and the female groups (P < 0.05).

CONCLUSIONS

The current study found a remarkable association between FKBP5 gene variations and the risk of comorbid CAD and depression in a north Chinese population. rs9470079 may be a potential gene locus for the incidence of comorbid CAD and depression.

Salivary cortisol response to psychosocial stress in the late evening depends on CRHR1 genotype

The activation of the hypothalamus-pituitary-adrenal (HPA) axis is induced by stress. Imbalances in this system increase the risk of developing stress related disorders including mental illness. Variants in the single nucleotide polymorphism (SNP) rs110402 of the corticotropin-releasing hormone receptor type I (CRHR1) gene have been shown in interaction with childhood maltreatment to increase the vulnerability to develop depressive symptoms in adulthood. In this study, the direct contribution of polymorphism of the CRHR1 gene (rs110402) to the salivary cortisol response to stress independently from childhood adversity was investigated. Healthy young men between the ages of 18 and 30, free from childhood maltreatment and early trauma, were genotyped (n = 121). To increase the power of the genetic analysis, only homozygous carriers of the common C (n = 31) and of the rare T (n = 21) allele were selected for this study and exposed to a Trier Social Stress Test (TSST) in the late evening (22.30 to 22.40). Salivary samples for the assessment of cortisol and its inactive metabolite cortisone were taken early in the evening (20.00), just before (22.30) and immediately after (22.40) as well as 15 minutes after stress exposure (22.55). Participants with the TT genotype showed higher cortisol levels 15 minutes post stress compared to participants with the CC genotype. No genotype differences were found for cortisone. Interestingly, TT participants reported lower subjective perceived stress levels before the TSST, but not after stress exposure. These results confirm that variants of rs110402 in the CRHR1 gene contribute to an increased stress response. Contrary to previous findings, however, this effect could be observed in subjects reporting no exposure to childhood maltreatment or early trauma.

Correlation between hypothalamic-pituitary-adrenal axis gene polymorphisms and posttraumatic stress disorder symptoms

BACKGROUND

The hypothalamic-pituitary-adrenal (HPA) axis is the main neuroendocrine system that controls stress responses, including fear learning. To further understand the correlation between the HPA axis and stress- and fear-related symptoms in humans, the current study investigated the relationship between HPA axis gene polymorphisms and a stress- and fear-related disorder, posttraumatic stress disorder (PTSD). This is the first study that systematically investigates the correlations between HPA axis genes and distinct PTSD symptom clusters.

METHODS

Participants included 1132 Chinese earthquake survivors (772 women and 360 men). PTSD symptoms were measured by the PTSD Checklist for DSM-5 (PCL-5), and the severity (total symptoms) and symptom clusters were calculated according to the hybrid seven-factor model of DSM-5 PTSD. We genotyped eight single nucleotide polymorphisms (SNPs) of three HPA axis genes, including FKBP5, CRHR1 and CRHR2.

RESULTS

The main effects of the CRHR2 SNP rs2267715 were associated with PTSD severity (P = 0.0035) and all PTSD symptom clusters except dysphoric arousal (P ranging from 0.0011 to 0.048). In women, a gene-environment interaction (G × E) effect of FKBP5 (rs3800373 × trauma exposure) was correlated with PTSD severity (P = 0.038), externalizing behaviors, anxious arousal and dysphoric arousal symptoms (P ranging from 0.014 to 0.028); the G × E effect of CRHR1 (rs4458044 × trauma exposure) was associated with anxious arousal symptoms (P = 0.016). In men, a gene-gene interaction (G × G) effect of FKBP5-CRHR1 (rs9470080 × rs4458044) was associated with PTSD severity (P = 0.0091), intrusion, negative affect, externalizing behaviors and anxious arousal (P ranging 0.012-0.049).

CONCLUSION

Our results systematically revealed that the main effects and G × E and G × G effects of some genetic polymorphisms of HPA axis genes are involved in the severity and distinct symptom clusters of PTSD.

Role of the FKBP5 polymorphism rs1360780, age, sex, and type of surgery in weight loss after bariatric surgery: a follow-up study

BACKGROUND

Emerging evidence suggests that the FK506 binding protein 51 (FKBP5/FKBP51), encoded by the FKBP5 gene, influences weight and metabolic regulation. The T allele of a functional polymorphism in FKBP5 (rs1360780), has been associated with the expression of FKBP51 and weight loss after bariatric surgery.

OBJECTIVE

To examine the role of the FKBP5 rs1360780 polymorphism in relation to age, sex, and type of surgery in weight loss after bariatric surgery in patients with severe obesity.

SETTING

University Hospital in Spain METHODS: A cohort of 151 obese patients submitted to Roux-en-Y gastric bypass (62.3%) and sleeve gastrectomy (37.7%) were followed-up during 24-months (t_24m; loss to follow-up: 0%). During the postoperative period body mass index (BMI) and percentage of excess and total weight loss were evaluated.

RESULTS

The BMI analysis showed an effect of the interaction FKBP5 genotype by sex (P = .0004) and a tendency to the interaction genotype by surgery (P = .048), so that men carrying the T allele had higher BMI at t_24m than those without the T allele, and T-allele carriers that underwent sleeve gastrectomy had higher BMI at t_24m than the noncarriers. Additionally, we found an interaction between FKBP5 and age for the percentage of excess weight loss and BMI (P = .0005 and P = 1.5e-7, respectively), whereby individuals >48 years with the T allele displayed significant differences for the analyzed variables at t_24m compared with the homozygotes for the alternate C allele showing lower weight loss.

CONCLUSION

FKBP5 rs1360780 genotype has specific effects on weight loss outcomes after bariatric surgery depending on sex, age, and type of surgery, suggesting worse results in older males carrying the T allele who have undergone sleeve gastrectomy.

BDNF genetic variants and methylation: effects on cognition in major depressive disorder

Brain-derived neurotrophic factor (BDNF) gene regulation has been linked to the pathophysiology of major depressive disorder (MDD). MDD patients show cognitive deficits, and altered BDNF regulation has a relevant role in neurocognitive functions. Our goal was to explore the association between BDNF genetic and epigenetic variations with neurocognitive performance in a group of MDD patients and healthy controls considering possible modulating factors. The sample included 134 subjects, 64 MDD patients, and 70 healthy controls. Clinical data, childhood maltreatment, and neurocognitive performance were assessed in all participants. Eleven single nucleotide polymorphisms (SNPs) and two promoter regions in the BDNF gene were selected for genotype and methylation analysis. The role of interactions between BDNF genetic and epigenetic variations with MDD diagnosis, sex, and Childhood Trauma Questionnaire (CTQ) scores was also explored. We observed significant associations between neurocognitive performance and two BDNF SNPs (rs908867 and rs925946), an effect that was significantly mediated by methylation values at specific promoter I sites. We identified significant associations between neurocognitive results and methylation status as well as its interactions with MDD diagnosis, sex, and CTQ scores. Our results support the hypothesis that BDNF gene SNPs and methylation status, as well as their interactions with modulating factors, can influence cognition. Further studies are required to confirm the effect of BDNF variations and cognitive function in larger samples.

The cellular and molecular basis of major depressive disorder: towards a unified model for understanding clinical depression

Major depressive disorder (MDD) is considered a serious public health issue that adversely impacts an individual's quality of life and contributes significantly to the global burden of disease. The clinical heterogeneity that exists among patients limits the ability of MDD to be accurately diagnosed and currently, a symptom-based approach is utilized in many cases. Due to the complex nature of this disorder, and lack of precise knowledge regarding the pathophysiology, effective management is challenging. The aetiology and pathophysiology of MDD remain largely unknown given the complex genetic and environmental interactions that are involved. Nonetheless, the aetiology and pathophysiology of MDD have been the subject of extensive research, and there is a vast body of literature that exists. Here we overview the key hypotheses that have been proposed for the neurobiology of MDD and highlight the need for a unified model, as many of these pathways are integrated. Key pathways discussed include neurotransmission, neuroinflammation, clock gene machinery pathways, oxidative stress, role of neurotrophins, stress response pathways, the endocannabinoid and endovanilloid systems, and the endogenous opioid system. We also describe the current management of MDD, and emerging novel therapies, with particular focus on patients with treatment-resistant depression (TRD).