Investigating the first genomic response to stress – insights into the etiology and pathophysiology of major depression
Ontology highlight
ABSTRACT: While exposure to adverse life events and subsequent dysregulation of the stress hormone response broadly confer risk for depression, the specific molecular mechanisms mediating this risk are poorly understood. Through pharmacologic activation of the stress hormone response in blood cells we demonstrate that common genetic variants in long-range enhancer elements moderate the immediate transcriptome response to stress, and that these genetic differences are associated with increased risk for depression in the context of early adversity. Using imaging genetics we then link these common risk variants with dysregulated amygdala reactivity, an important trigger of the stress hormone response. The transcripts regulated by these risk variants in peripheral blood were also responsive to stress and stress hormone receptor activation in murine brain. Network modeling approaches suggest that these differences in transcriptional activation may mediate stress-related risk for depression by altering a functional gene network related to proteasome degradation and synaptic plasticity. A Dexamethasone Suppression Test was performed in 160 male subjects. Baseline and stimulated (3 hours after 1.5 mg dexamethasone p.o.) whole blood samples were analyzed using Illumina Human HT-12 v3 arrays.
Project description:Depression risk is exacerbated by genetic factors and stress exposure; however, the biological mech- anisms through which these factors interact to confer depression risk are poorly understood. One putative biological mechanism implicates variability in the ability of cortisol, released in response to stress, to trigger a cascade of adaptive genomic and non-genomic processes through glucocorticoid receptor (GR) activation. Here, we demonstrate that common genetic variants in long-range enhancer elements modulate the immediate transcriptional response to GR activation in human blood cells. These functional genetic variants increase risk for depression and co-heritable psychiatric disorders. Moreover, these risk variants are associated with inappropriate amygdala reactivity, a transdiagnostic psychiatric endophenotype and an important stress hormone response trigger. Network modeling and animal experiments suggest that these genetic dif- ferences in GR-induced transcriptional activation may mediate the risk for depression and other psy- chiatric disorders by altering a network of function- ally related stress-sensitive genes in blood and brain.
Project description:Background: Sepsis, a leading cause of morbidity and mortality, is not a homogeneous disease but rather a syndrome encompassing many heterogeneous pathophysiologies. Patient factors including genetics predispose to poor outcomes, though current clinical characterizations fail to identify those at greatest risk of progression and mortality. Results: The Community Acquired Pneumonia and Sepsis Outcome Diagnostic study enrolled 1,152 subjects with suspected sepsis. We sequenced peripheral blood RNA of 129 representative subjects with systemic inflammatory response syndrome (SIRS) or sepsis (infection with SIRS), including 78 sepsis survivors and 28 sepsis nonsurvivors, who had previously undergone plasma proteomic and metabolomic profiling. The expression of 338 genes differed between subjects with SIRS and those with sepsis, primarily reflective of immune activation in sepsis. The expression of 1,238 genes differed with sepsis outcome: Nonsurvivors had lower expression of many immune function-related genes. Functional genetic variants associated with sepsis mortality were sought based on a common disease â rare variant hypothesis. VPS9D1, whose expression was increased in sepsis survivors, had a higher burden of missense variants in sepsis survivors, and these were associated with altered expression of 3,799 genes, primarily reflecting Golgi and endosome biology. Conclusions: Host response in sepsis survivors â activation of immune response-related genes â was muted in sepsis nonsurvivors. The association of sepsis survival with robust immune response and presence of missense variants in VPS9D1 warrants replication and further functional studies. We sequenced peripheral blood RNA of 129 representative subjects with systemic inflammatory response syndrome (SIRS, n=23) or sepsis (infection with SIRS), including 78 sepsis survivors and 28 sepsis nonsurvivors, who had previously undergone plasma proteomic and metabolomic profiling.
Project description:Although the specific functions of sleep have not been completely elucidated, the literature has suggested that sleep is essential for proper homeostasis. Sleep loss is associated with changes in behavioral, neurochemical, cellular, and metabolic functions as well as impaired immune response. We evaluated the gene expression profiles of healthy volunteers submitted to 48 hours of prolonged wakefulness (PW) followed by 12 hours of sleep recovery (SR) using high-resolution microarrays. Peripheral whole blood was collected in the morning before the initiation of sleep deprivation (baseline), after the second night of PW, and one night after SR. the identified differentially expressed genes were related to immune response, DNA damage and repair as well as inflammation. Examples of these include: killer cell lectin-like receptors family granzymes and T-cell receptors, which play important roles in host defense. These results support the idea that sleep loss can lead to alteration of molecular processes that drive perturbation of cellular immunity, induction of inflammatory response and homeostatic imbalance. Moreover, down-regulation of multiple genes after prolonged wakefulness (in comparison with baseline condition) and up-regulated after sleep recovery (in comparison with prolonged wakefulness condition) were observed, suggesting an attempt of the body to re-establish internal homeostasis. In silico validation of alterations in the expression of CETN3, DNAJC, IGFR2B and CEACAM genes, confirmed the previous findings related to the molecular effects of sleep deprivation. It is clear that confirmatory studies will be necessary to fully validate the potential candidate genes and functional networks identified. Nevertheless, the present findings confirm that the effects of sleep deprivation are not restricted to the brain and can occur intensely in peripheral tissues. The peripheral blood from each volunteer (nine individuals) were collected in the baseline night and every morning after PW and after the night of SR.
Project description:Whole genome gene expression data (baseline and following GR-stimulation with 1.5 mg dexamethasone p.o.) were analysed to identify glucocorticoid receptor (GR)-mediated changes in gene expression. A Dexamethasone Suppression Test was performed in 297 subjects. Baseline and stimulated (3 hours after 1.5 mg dexamethasone p.o.) whole blood samples were analyzed using Illumina Human HT-12 v3 and v4 arrays.
Project description:The aim of the experiment was to assign patients enrolled in the VANISH randomised trial to sepsis response signature (SRS) endotypes based on a previously published gene expression signature, in order to test for differential responses to treatment. VANISH was a double-blind randomised clinical trial in septic shock, with patients randomised to receive norepinephrine or vasopressin followed by hydrocortisone or placebo. We collected blood samples upon enrolment, extracted RNA and performed transcriptomic profiling using microarrays, allocated patients to SRS1 or SRS2 using a linear model (Davenport 2016), and tested for an association between sepsis endotype and response to either norepinephrine or vasopressin, or to corticosteroids. There was a significant interaction between treatment with hydrocortisone or placebo, and SRS endotype (p=0·02)
Project description:Depression, or major depressive disorder, poses a significant burden for both individuals and society, affecting approximately 10.8% of the general population. This psychiatric disorder leads to approximately 800,000 deaths per year. A combination of genetic and environmental factors such as early life stress (ELS) increase the risk for development of depression in humans, and a clear role for the hippocampus in the pathophysiology of depression has been shown. Nevertheless, the underlying mechanisms of depression remain poorly understood, resulting in a lack of effective treatments. To better understand the core mechanisms underlying the development of depression, we used a cross-species design to investigate shared hippocampal pathophysiological mechanisms in mouse ELS and human depression. Mice were subjected to ELS by a maternal separation paradigm, followed by RNA sequencing analysis of the adult hippocampal tissue. This identified persistent transcriptional changes linked to mitochondrial stress response pathways, with oxidative phosphorylation and protein folding emerging as the main mechanisms affected by maternal separation. Remarkably, there was a significant overlap between the pathways involved in mitochondrial stress response we observed and publicly available RNAseq data from hippocampal tissue of depressive patients. This cross-species conservation of changes in gene expression of mitochondria-related genes suggests that mitochondrial stress may play a pivotal role in the development of depression. Our findings highlight the potential significance of the hippocampal mitochondrial stress response as a core mechanism underlying the development of depression. Further experimental investigations are required to expand our understanding of these mechanisms
Project description:The host response in critically ill patients with sepsis, septic shock remains poorly defined. Considerable research has been conducted to accurately distinguish patients with sepsis from those with non-infectious causes of disease. Technological innovations have positioned systems biology at the forefront of biomarker discovery. Analysis of the whole-blood leukocyte transcriptome enables the assessment of thousands of molecular signals beyond simply measuring several proteins in plasma, which for use as biomarkers is important since combinations of biomarkers likely provide more diagnostic accuracy than the measurement of single ones or a few. Evidence suggests that genome-wide transcriptional profiling of blood leukocytes can assist in differentiating between infection and non-infectious causes of severe disease. Of importance, RNA biomarkers have the potential advantage that they can be measured reliably in rapid quantitative reverse transcriptase polymerase chain reaction (qRT-PCR)-based point of care tests. PAXgene blood RNA was isolated at intensive-care unit (ICU) admission and throughout ICU length-of-stay. Through the use of genome-wide microarrays we aimed to identify molecular features that enbale the adequate discrimination of infectious and non-infectious sources of critical illness. Moreover, biological pathway analysis was used to tease out the most relevant biological units in sepsis and septic shock.
Project description:Adjuvants are critical for the success of vaccines, and agonists for microbial pattern recognition receptors are promising new candidates. A mechanism for the immune enhancing role of adjuvants is to stimulate innate immunity. We studied the innate immune response in humans to synthetic double stranded RNA (poly ICLC), a ligand for TLR3 and MDA-5 cytosolic RNA helicase. Transcriptional analysis of blood samples from eight volunteers, after subcutaneous administration of poly ICLC showed upregulation of genes involved in multiple innate immune pathways in all subjects, including interferon and inflammasome signaling. Blocking of type I interferon receptor ex vivo significantly dampened the response to poly IC. Comparative transcriptional analysis showed that several innate pathways were similarly induced in volunteers immunized with the highly efficacious Yellow Fever Vaccine. Therefore a chemically defined microbial agonist like poly ICLC can be a reliable and authentic microbial mimic for inducing innate immunity, here for a live attenuated viral vaccine in humans. GSM813292-GSM813386: RNA expression obtained at different time points from Human blood after poly ICLC administration compared to RNA expression obtained from Human blood after placebo administration GSM813387-GSM813410: Blocking of type I interferon receptor ex vivo followed by poly IC stimulation
Project description:We hypothesized that microarray analyses of whole blood gene expression would identify patterns of gene expression useful in the diagnosis for sacroidosis and identify inflammatory mediators relevant to the underlying pathophysiology. We analyzed whole blood RNA from 37 patients with sarcoidosis, 20 healthy controls and 6 patients with hypersensitivity pneumonitis using genome-wide expression microarrays. We developed a classification algorithm using a derivation and validation subset approach, analyzed the most discriminative gene expression changes, and confirmed selected expression changes using flow-cytometry.
Project description:Here, we selected >1000 variants from over 30 depression-associated loci using brain epigenomic data, and functionally assayed them using in vivo functional assays in the mouse brain to examine sex-by-genotype interactions. We identify extensive sex-by-allele effects in mature hippocampus, suggesting genetic risk and thus disease mechanisms may be distinct between the sexes. Unbiased informatics approaches indicated a role for nuclear hormone receptors, which was supported by . Further, comparative analysis of allelic function in the neonatal mouse brain, during a key between developmental neonates during the masculinizing testosterone surge, and in the adult hippocampus—a region of interest in depression pathology—but not at 10 days old, a older hormonally quiescent developmental stage juveniles. Our study provides novel insights into depression genetics as influenced by age, biological sex, and cell type, and provides a framework for in vivo parallel assays at a scale not previously shown possible to functionally define interactions between sex and disease variation.