Childhood trauma, suicide risk and inflammatory phenotypes of depression: insights from monocyte gene expression

Immunological alterations in patients with current and lifetime suicide ideation and attempts: Examining the relationship with depressive symptoms

Background

Suicidal ideation and attempt (SI/SA) have been associated with dysregulation of the immune response and inflammation. However, few studies have explored how innate and acquired cellular immunity impact on the peripheral immune response. Our study addresses this gap by examining the composition of peripheral immune cells and humoral markers among individuals with current SI/SA, individuals with a history of SI/SA, and healthy controls (HC). Additionally, we aim to explore whether depressive symptoms settle the relationship between inflammation and SI/SA.

Methods

This is a multicenter case-control study that included 105 participants. Clinical and demographic characterists together with hemogram parameters, soluble pro and anti-inflamatory factors, and specific innate and adaptive immune cell populations were compared among patients with current SI/SA (n = 21), a history of lifetime SI/SA (n = 42), and HC (n = 42).

Results

Patients with both current and lifetime SI/SA had a significant increase in the absolute count of monocytes and in the monocyte/lymphocyte ratio (MLR). Additionally, patients with current and lifetime SI/SA showed a significant increase in high-sensitivity C- reactive protein (hs-CRP), and patients with lifetime SI/SA also showed higher levels of Erythrocyte Sedimentation Rate (ESR). The cellular inflammatory status of patients with SI/SA was characterized by altered proportions of monocytes with higher levels of nonclassical and intermediate monocytes. No differences were observed in the number of lymphocytes and the proportion of CD4 and CD8 between patients and HC, but we found differences in markers of exhaustion of CD4 lymphocytes, with increased levels of Programmed cell death protein 1 (PD1) in Current SI/SA and Lymphocyte activation gene 3 (LAG3) in Current SI/SA and Lifetime SI/SA compared to HC. The plasmainflammatory status was marked by higher levels of soluble Triggering receptor expressed on myeloid cells 2 (sTREM2) in patients with lifetime SI/SA compared to HC. Finally, the multinomial analysis indicates that inflammation and depressive symptoms are independently associated with SI/SA.

Conclusion

This study highlights the association of immunological alterations with SI/SA. Furthremore, SI/SA is independently influenced by depressive symptoms and inflammation. This may have important therapeutic implications, as in these patients, it may be necessary to treat the inflammatory process beyond treating the depressive symptoms.

Peripheral blood cellular immunophenotype in suicidal ideation, suicide attempt, and suicide: a systematic review and meta-analysis

Previous meta-analyses have documented the association of immune-inflammatory pathways with the pathophysiology of Major Depressive Episode (MDE), as reflected by alterations in peripheral blood immune cell counts. However, it remains unclear whether these immunological changes are distinct in individuals experiencing suicidal ideation (SI) or suicidal behavior (SB), beyond the context of an MDE. This systematic review and meta-analysis aimed to examine peripheral immune cell profiles across samples with SI/SB and compare them to healthy controls or patients with MDE. A systematic literature search was conducted in MEDLINE, Embase, and PsycINFO for articles published from inception until June 12, 2023. Two independent reviewers screened the articles for inclusion, extracted data, and assessed the risk of bias using the Newcastle-Ottawa scale. Meta-analyses were performed using a random-effects model to calculate standardized mean differences (SMDs) and 95% confidence intervals (CIs) for immune cell counts or ratios between groups with and without SI/SB. Heterogeneity across studies was assessed using the restricted maximum-likelihood estimator for tau statistic and I2-statistic and tested by the Q test. Publication bias was evaluated using the Egger´s test and funnel plots. Meta-regression analyses were conducted to explore the potential moderating effects of age, gender, current or lifetime SI/SB, and the type of self-harming behavior (SI or SB). The study was registered with PROSPERO (CRD42023433089). The systematic review included 30 studies, with data from 19 studies included in the meta-analyses comprising 139 unique comparisons. Eleven different cell populations or ratios were included, comprising 1973 individuals with SI/SB and 5537 comparison subjects. White blood cell (WBC) and neutrophil counts were higher in individuals with SI/SB than in controls (WBC: SMD = 0.458; 95% CI = 0.367-0.548; p value ≤ 0.001; I2 = 0.002% and; Neutrophils: SMD = 0.581; 95% CI = 0.408-0.753; p < 0.001), indicating an inflammatory process. The neutrophil-to-lymphocyte ratio (NLR) emerged as a potential marker, demonstrating a notable elevation in individuals with SI/SB (SMD = 0.695; 95% CI = 0.054-1.335; p value = 0.033; I2 = 94.281%; Q test p value ≤ 0.001). The elevated NLR appears to be primarily driven by the increase in neutrophil counts, as no significant differences were found in lymphocyte counts between groups. Comparisons among participants with and without SI/SB and depression revealed similar trends with increased NLR, monocyte-to-lymphocyte ratio (MLR), and platelet-to-lymphocyte ratio (PLR) observed in depressed individuals with SI/SB compared to those without SI/SB. Broad alteration in the peripheral immune cell populations and their ratios were observed in individuals with SI/SB, indicating an immune activation or dysfunction. Notably, these immunological changes were also evident when comparing MDE individuals with and without SI/SB, suggesting that such immune dysfunction associated with suicidality cannot be solely attributed to or explained by depressive symptoms. The NLR, MLR, and PLR ratios, in combination with novel immune cellular and protein biomarkers, open new avenues in understanding the immunological underpinnings of SI/SB. These findings highlight the potential utility of immune markers as part of a multi-modal approach for risk stratification and therapeutic monitoring in SI/SB.

Evaluation of peripheral inflammatory parameters of cases with suicide attempts

PURPOSE

The purpose of the present study was to examine the inflammation markers of patients who have attempted suicide by comparing them with those of healthy controls. The leukocyte cell levels, Neutrophil/Lymphocyte Ratios (NLR), Basophil/Lymphocyte Ratios (BLR), Platelet/Lymphocyte Ratios (PLR), Monocyte/Lymphocyte Ratios (MLR), Systemic Inflammation Index (SII), Neutrophil/Albumin Ratios (NAR) values were compared with those of healthy controls.

METHOD

A total of 376 people were included in the study (276 patients who attempted suicide, and 100 healthy people (the control group)). The demographic data and laboratory parameters of the participants were analyzed from the hospital automation system.

RESULTS

The participants' female/male ratio was 158/118 (42.8%/57.1%) in the group of patients who attempted suicide and 41/59 (41/59%) in the control group. When the distribution of laboratory parameters was evaluated, although the NLR, BLR, NAR, SII, and MLR values, which are indicators of peripheral inflammation, were high in patients who attempted suicide (p = 0.049 for MLR, p = 0.000 for other values), the PLR (p = 0.586) value did not differ significantly between the groups. Patients who had attempted more than one suicide had elevated BLR (p = 0.007), SII (p = 0.003), and NAR (p = 0.003) values.

DISCUSSION

Based on the results obtained, it was considered that paying attention to inflammation parameters in patient follow-ups, and monitoring of SII, NLR, BLR, and NAR values of patients who had attempted suicide once would be beneficial in preventing future suicide attempts. These results strengthen the idea that inflammatory processes play roles in the pathophysiology of suicidal behavior. However, further studies are needed to elucidate the complex pathophysiological mechanisms of immune pathways underlying suicidal behavior.

Pro-inflammatory cytokines in stress-induced depression: Novel insights into mechanisms and promising therapeutic strategies

Stress-mediated depression is one of the common psychiatric disorders with a high prevalence and suicide rate, there is a lack of effective treatment. Accordingly, effective treatments with few adverse effects are urgently needed. Pro-inflammatory cytokines (PICs) may play a key role in stress-mediated depression. Thereupon, both preclinical and clinical studies have found higher levels of IL-1β, TNF-α and IL-6 in peripheral blood and brain tissue of patients with depression. Recent studies have found PICs cause depression by affecting neuroinflammation, monoamine neurotransmitters, hypothalamic pituitary adrenal axis and neuroplasticity. Moreover, they play an important role in the symptom, development and progression of depression, maybe a potential diagnostic and therapeutic marker of depression. In addition, well-established antidepressant therapies have some relief on high levels of PICs. Importantly, anti-inflammatory drugs relieve depressive symptoms by reducing levels of PICs. Collectively, reducing PICs may represent a promising therapeutic strategy for depression.

Adverse childhood experience and depression: the role of gut microbiota

Depression is the most common psychiatric disorder that burdens modern society heavily. Numerous studies have shown that adverse childhood experiences can increase susceptibility to depression, and depression with adverse childhood experiences has specific clinical-biological features. However, the specific neurobiological mechanisms are not yet precise. Recent studies suggest that the gut microbiota can influence brain function and behavior associated with depression through the "microbe-gut-brain axis" and that the composition and function of the gut microbiota are influenced by early stress. These studies offer a possibility that gut microbiota mediates the relationship between adverse childhood experiences and depression. However, few studies directly link adverse childhood experiences, gut microbiota, and depression. This article reviews recent studies on the relationship among adverse childhood experiences, gut microbiota, and depression, intending to provide insights for new research.

Decoding and reconstructing disease relations between dry eye and depression: a multimodal investigation comprising meta-analysis, genetic pathways and Mendelian randomization

INTRODUCTION

The clinical presentations of dry eye disease (DED) and depression (DEP) often comanifest. However, the robustness and the mechanisms underlying this association were undetermined.

OBJECTIVES

To this end, we set up a three-segment study that employed multimodality results (meta-analysis, genome-wide association study [GWAS] and Mendelian randomization [MR]) to elucidate the association, common pathways and causality between DED and DEP.

METHODS

A meta-analysis comprising 26 case-control studies was first conducted to confirm the DED-DEP association. Next, we performed a linkage disequilibrium (LD)-adjusted GWAS and targeted phenotype association study (PheWAS) in East Asian TW Biobank (TWB) and European UK Biobank (UKB) populations. Single-nucleotide polymorphisms (SNPs) were further screened for molecular interactions and common pathways at the functional gene level. To further elucidate the activated pathways in DED and DEP, a systemic transcriptome review was conducted on RNA sequencing samples from the Gene Expression Omnibus. Finally, 48 MR experiments were implemented to examine the bidirectional causation between DED and DEP.

RESULTS

Our meta-analysis showed that DED patients are associated with an increased DEP prevalence (OR = 1.83), while DEP patients have a concurrent higher risk of DED (OR = 2.34). Notably, cross-disease GWAS analysis revealed that similar genetic architecture (rG = 0.19) and pleiotropic functional genes contributed to phenotypes in both diseases. Through protein-protein interaction and ontology convergence, we summarized the pleiotropic functional genes under the ontology of immune activation, which was further validated by a transcriptome systemic review. Importantly, the inverse variance-weighted (IVW)-MR experiments in both TWB and UKB populations (p value <0.001) supported the bidirectional exposure-outcome causation for DED-to-DEP and DEP-to-DED. Despite stringent LD-corrected instrumental variable re-selection, the bidirectional causation between DED and DEP remained.

CONCLUSION

With the multi-modal evidence combined, we consolidated the association and causation between DED and DEP.

Understanding the Biological Relationship between Migraine and Depression

Migraine is a highly prevalent neurological disorder. Among the risk factors identified, psychiatric comorbidities, such as depression, seem to play an important role in its onset and clinical course. Patients with migraine are 2.5 times more likely to develop a depressive disorder; this risk becomes even higher in patients suffering from chronic migraine or migraine with aura. This relationship is bidirectional, since depression also predicts an earlier/worse onset of migraine, increasing the risk of migraine chronicity and, consequently, requiring a higher healthcare expenditure compared to migraine alone. All these data suggest that migraine and depression may share overlapping biological mechanisms. Herein, this review explores this topic in further detail: firstly, by introducing the common epidemiological and risk factors for this comorbidity; secondly, by focusing on providing the cumulative evidence of common biological aspects, with a particular emphasis on the serotoninergic system, neuropeptides such as calcitonin-gene-related peptide (CGRP), pituitary adenylate cyclase-activating polypeptide (PACAP), substance P, neuropeptide Y and orexins, sexual hormones, and the immune system; lastly, by remarking on the future challenges required to elucidate the etiopathological mechanisms of migraine and depression and providing updated information regarding new key targets for the pharmacological treatment of these clinical entities.

Embers of the Past: Early Childhood Traumas Interact with Variation in P2RX7 Gene Implicated in Neuroinflammation on Markers of Current Suicide Risk

Both early childhood traumatic experiences and current stress increase the risk of suicidal behaviour, in which immune activation might play a role. Previous research suggests an association between mood disorders and P2RX7 gene encoding P2X7 receptors, which stimulate neuroinflammation. We investigated the effect of P2RX7 variation in interaction with early childhood adversities and traumas and recent stressors on lifetime suicide attempts and current suicide risk markers. Overall, 1644 participants completed questionnaires assessing childhood adversities, recent negative life events, and provided information about previous suicide attempts and current suicide risk-related markers, including thoughts of ending their life, death, and hopelessness. Subjects were genotyped for 681 SNPs in the P2RX7 gene, 335 of which passed quality control and were entered into logistic and linear regression models, followed by a clumping procedure to identify clumps of SNPs with a significant main and interaction effect. We identified two significant clumps with a main effect on current suicidal ideation with top SNPs rs641940 and rs1653613. In interaction with childhood trauma, we identified a clump with top SNP psy_rs11615992 and another clump on hopelessness containing rs78473339 as index SNP. Our results suggest that P2RX7 variation may mediate the effect of early childhood adversities and traumas on later emergence of suicide risk.

The Impact of Complex Trauma on Occupations and Daily Functioning in Childhood: A Scoping Review

AIMS

To explore the impact of complex trauma on occupations and daily functioning in childhood through empirical studies and asses the extent and state of available evidence.

METHODS

The five-stage scoping review framework by Arksey and O'Malley and the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR: Tricco et al.) were followed. EMBASE, MEDLINE, CINAHL, PsychINFO, and Web of Science databases were systematically searched. Included studies were empirical research published in English up to December 2022, reporting on the impact of complex trauma on daily functioning or occupations in children experiencing such trauma, defined as prolonged exposure to interpersonal trauma arising within the primary caregiving system.

RESULTS

Eight studies were included. They reported impacts on personal and instrumental activities of daily living, sleep, education, work, play, leisure, and social participation. Some domains lacked comprehensive investigation, and studies lacked descriptions of specific effects on these areas.

CONCLUSIONS

The review reveals a lack of robust empirical evidence on the impact of complex trauma on occupations and daily functioning in childhood, with limited depth for comprehensive analysis on the extent of children's occupational life impact. Further research is warranted to address identified gaps.

Association of psychological distress and DNA methylation: A 5-year longitudinal population-based twin study

AIM

To identify the psychological distress (PD)-associated 5'-cytosine-phosphate-guanine-3' sites (CpGs), and investigate the temporal relationship between dynamic changes in DNA methylation (DNAm) and PD.

METHODS

This study included 1084 twins from the Chinese National Twin Register (CNTR). The CNTR conducted epidemiological investigations and blood withdrawal twice in 2013 and 2018. These included twins were used to perform epigenome-wide association studies (EWASs) and to validate the previously reported PD-associated CpGs selected from previous EWASs in PubMed, Embase, and the EWAS catalog. Next, a cross-lagged study was performed to examine the temporality between changes in DNAm and PD in 308 twins who completed both 2013 and 2018 surveys.

RESULTS

The EWAS analysis of our study identified 25 CpGs. In the validation analysis, 741 CpGs from 29 previous EWASs on PD were selected for validation, and 101 CpGs were validated to be significant at a false discovery rate <0.05. The cross-lagged analysis found a unidirectional path from PD to DNAm at 14 CpGs, while no sites showed significance from DNAm to PD.

CONCLUSIONS

This study identified and validated PD-related CpGs in a Chinese twin population, and suggested that PD may be the cause of changes in DNAm over time. The findings provide new insights into the molecular mechanisms underlying PD pathophysiology.

Peripheral Markers of Suicidal Behavior: Current Findings and Clinical Implications

Biomarkers of suicidal behavior (SB), particularly peripheral biomarkers, may aid in the development of preventive and intervention strategies. The peripheral biomarkers of SB should be easily accessible, cost-effective, and minimally invasive. To identify peripheral biomarkers of SB, we summarized the current knowledge related to SB biomarkers with a focus on suicidal outcomes (suicidal ideation [SI], suicide risk [SR], suicide attempt [SA], and suicide death [SD]), measured site (center or periphery), and study design (cross-sectional or longitudinal). We also evaluated the central findings to validate the findings of peripheral biomarkers of SB. We found reduced peripheral interleukin (IL)-2 levels in individuals with a recent SA, higher cerebrospinal fluid (CSF) IL-6 levels in patients with a current SR and future SD, higher CSF tumor necrosis factor-α levels for current and future SRs, higher high-sensitivity C-reactive protein levels and lower peripheral total cholesterol levels for recent SAs, lower peripheral 5-HT levels for present SR, and a lower folate level for future SR and SA within 1 year. Previous studies have shown inconsistent associations of low peripheral leptin levels with SR and recent SA; therefore, further study is required. Given the multiple determinants of SB and weak associations with single biological markers, combinations of potential biological markers rather than single markers may improve the screening, diagnosis, and prediction of SB.

Examining the Relationships between the Incidence of Infectious Diseases and Mood Disorders: An Analysis of Data from the Global Burden of Disease Studies, 1990-2019

Mood disorders are among the commonest mental disorders worldwide. Epidemiological and clinical evidence suggests that there are close links between infectious diseases and mood disorders, but the strength and direction of these association remain largely unknown. Theoretical models have attempted to explain this link based on evolutionary or immune-related factors, but these have not been empirically verified. The current study examined cross-sectional and longitudinal associations between the incidence of infectious diseases and mood disorders, while correcting for climate and economic factors, based on data from the Global Burden of Disease Studies, 1990-2019. It was found that major depressive disorder was positively associated with lower respiratory infections, while bipolar disorder was positively associated with upper respiratory infections and negatively associated with enteric and tropical infections, both cross-sectionally and over a period of 30 years. These results suggest that a complex, bidirectional relationship exists between these disorders. This relationship may be mediated through the immune system as well as through the gut-brain and lung-brain axes. Understanding the mechanisms that link these groups of disorders could lead to advances in the prevention and treatment of both.

Risk of Attempted Suicide Among Patients With IBD: A Nationwide Longitudinal Follow-up Study

BACKGROUND

Evidence suggests that IBD is related to an increased risk of depressive disorder and suicide.

OBJECTIVES

Whether IBD is an independent risk factor for suicide remains unclear.

DESIGN

A matched cohort study design.

SETTINGS

Taiwan National Health Insurance Research Database.

PATIENTS

A total of 3625 adults with IBD aged ≥20 years and 36,250 matched controls were selected between 1997 and 2013 and followed-up to the end of 2013.

MAIN OUTCOME MEASURES

Any suicide attempt was identified during the study period. Stratified Cox regression analysis was conducted on each matched pair to investigate the attempted suicide risk between the IBD and control groups.

RESULTS

The hazard ratio for any suicide attempt among the patients with IBD was 4.61 (95% CI, 3.29-6.48) compared with controls matched exactly for depressive disorder. No significant difference in suicide attempts was noted between patients with ulcerative colitis (HR, 4.12; 95% CI, 2.69-6.32) and patients with Crohn's disease (HR, 5.78; 95% CI, 3.27-10.22).

LIMITATIONS

The incidence of any suicide attempt may be underestimated.

CONCLUSION

IBD was an independent risk factor for attempted suicide. However, further studies are required to elucidate the definite pathomechanisms between IBD and suicide.

RIESGO DE INTENTO DE SUICIDIO ENTRE PACIENTES CON ENFERMEDAD INFLAMATORIA INTESTINAL UN ESTUDIO DE SEGUIMIENTO LONGITUDINAL A NIVEL NACIONAL

ANTECEDENTES: La evidencia sugiere que la enfermedad inflamatoria intestinal (EII) está relacionada con un mayor riesgo de trastornos depresivos y de suicidios.OBJETIVOS: Sin embargo, aún no está claro si la EII es un factor de riesgo independiente para llegar al suicidio.DISEÑO: Estudio de cohortes de tipo pareado.AJUSTES: Investigación en la base de datos del seguro nacional de salud de Taiwán.PACIENTES: Se seleccionaron un total de 3.625 adultos con EII de ≥20 años y 36.250 controes emparejados entre 1997 y 2013, se les dio un seguimiento hasta finales de 2013.PRINCIPALES MEDIDAS DE RESULTADO: Se identificó cualquier intento de suicidio durante el período del estudio. Se realizó un análisis de regresión de Cox estratificado en cada dupla apareada dentro la investigación del riesgo de intento de suicidio comparado entre los grupos de EII y el grupo control.RESULTADOS: El cociente de riesgo instantáneo (HR) para cualquier intento de suicidio entre los pacientes con EII fue de 4,61 (el intervalo de confianza [IC] del 95 %: 3,29-6,48) en comparación con los controles apareados exactamente en casos de trastorno depresivo. No se observaron diferencias significativas en los intentos de suicidio entre los pacientes con colitis ulcerosa (HR: 4,12, IC 95 %: 2,69-6,32) y enfermedad de Crohn (HR: 5,78, IC 95 %: 3,27-10,22).LIMITACIONES: La incidencia de cualquier intento de suicidio puede estar subestimada.CONCLUSIÓN: La EII fué un factor de riesgo independiente para el intento de suicidio. Sin embargo, se requieren más estudios para dilucidar los mecanismos patogénicos definitivos entre la EII y el suicidio. (Traducción-Dr. Xavier Delgadillo ).

Blood transcriptome analysis suggests an indirect molecular association of early life adversities and adult social anxiety disorder by immune-related signal transduction

Social anxiety disorder (SAD) is a psychiatric disorder characterized by severe fear in social situations and avoidance of these. Multiple genetic as well as environmental factors contribute to the etiopathology of SAD. One of the main risk factors for SAD is stress, especially during early periods of life (early life adversity; ELA). ELA leads to structural and regulatory alterations contributing to disease vulnerability. This includes the dysregulation of the immune response. However, the molecular link between ELA and the risk for SAD in adulthood remains largely unclear. Evidence is emerging that long-lasting changes of gene expression patterns play an important role in the biological mechanisms linking ELA and SAD. Therefore, we conducted a transcriptome study of SAD and ELA performing RNA sequencing in peripheral blood samples. Analyzing differential gene expression between individuals suffering from SAD with high or low levels of ELA and healthy individuals with high or low levels of ELA, 13 significantly differentially expressed genes (DEGs) were identified with respect to SAD while no significant differences in expression were identified with respect to ELA. The most significantly expressed gene was MAPK3 (p = 0.003) being upregulated in the SAD group compared to control individuals. In contrary, weighted gene co-expression network analysis (WGCNA) identified only modules significantly associated with ELA (p ≤ 0.05), not with SAD. Furthermore, analyzing interaction networks of the genes from the ELA-associated modules and the SAD-related MAPK3 revealed complex interactions of those genes. Gene functional enrichment analyses indicate a role of signal transduction pathways as well as inflammatory responses supporting an involvement of the immune system in the association of ELA and SAD. In conclusion, we did not identify a direct molecular link between ELA and adult SAD by transcriptional changes. However, our data indicate an indirect association of ELA and SAD mediated by the interaction of genes involved in immune-related signal transduction.

Reduced numbers of naïve CD4 + T cells and an altered CD4/CD8 balance in depressed common variable immune deficiency (CVID) patients. Is thymosin-α1 a possible treatment?

In the 1990's the macrophage-T-cell-theory of depression was posed stating that low grade inflammation and an abnormal T cell system destabilize the development and function of the emotional brain in such a way, that individuals become ultrasensitive to stress. Recently we gathered evidence that indeed higher frequencies of CD4+ memory T cells, lower frequencies of naive CD4 + T cells, higher frequencies of CD8 + T cells (the latter two in part elicited by Cytomegalovirus, CMV, infection) are a characteristic of Major Depressive Disorder (MDD). In MDD patients with a history of childhood trauma and severe depression monocytes are inflammatory activated. Low grade inflammation and T cell system defects have also been reported in patients with Common Variable Immune Deficiency (CVID) (next to antibody production defects). CVID patients show a higher prevalence of mild depression. The aim of this study was to determine T cell frequencies and monocyte inflammatory activation in CVID patients with and without depression. This study confirms that CVID patients have CMV independent decreases in the frequency of naïve CD4 + T cells and it de novo shows a CMV dependent increase in the expression of inflammatory genes in monocytes. CVID patients with depression are additionally characterized by a CMV independent increase in the frequency of naïve CD8 + T cells, while lacking monocyte inflammatory activation. In conclusion, depressed CVID patients have T cell abnormalities comparable to that of patients with regular MDD. These abnormalities are presently targeted by thymosin α1 in an open-label proof of concept trial.

Mycobacterium vaccae NCTC 11659, a Soil-Derived Bacterium with Stress Resilience Properties, Modulates the Proinflammatory Effects of LPS in Macrophages

Inflammatory conditions, including allergic asthma and conditions in which chronic low-grade inflammation is a risk factor, such as stress-related psychiatric disorders, are prevalent and are a significant cause of disability worldwide. Novel approaches for the prevention and treatment of these disorders are needed. One approach is the use of immunoregulatory microorganisms, such as Mycobacterium vaccae NCTC 11659, which have anti-inflammatory, immunoregulatory, and stress-resilience properties. However, little is known about how M. vaccae NCTC 11659 affects specific immune cell targets, including monocytes, which can traffic to peripheral organs and the central nervous system and differentiate into monocyte-derived macrophages that, in turn, can drive inflammation and neuroinflammation. In this study, we investigated the effects of M. vaccae NCTC 11659 and subsequent lipopolysaccharide (LPS) challenge on gene expression in human monocyte-derived macrophages. THP-1 monocytes were differentiated into macrophages, exposed to M. vaccae NCTC 11659 (0, 10, 30, 100, 300 µg/mL), then, 24 h later, challenged with LPS (0, 0.5, 2.5, 250 ng/mL), and assessed for gene expression 24 h following challenge with LPS. Exposure to M. vaccae NCTC 11659 prior to challenge with higher concentrations of LPS (250 ng/mL) polarized human monocyte-derived macrophages with decreased IL12A, IL12B, and IL23A expression relative to IL10 and TGFB1 mRNA expression. These data identify human monocyte-derived macrophages as a direct target of M. vaccae NCTC 11659 and support the development of M. vaccae NCTC 11659 as a potential intervention to prevent stress-induced inflammation and neuroinflammation implicated in the etiology and pathophysiology of inflammatory conditions and stress-related psychiatric disorders.

A machine learning approach on whole blood immunomarkers to identify an inflammation-associated psychosis onset subgroup

Psychosis onset is a transdiagnostic event that leads to a range of psychiatric disorders, which are currently diagnosed through clinical observation. The integration of multimodal biological data could reveal different subtypes of psychosis onset to target for the personalization of care. In this study, we tested the existence of subgroups of patients affected by first-episode psychosis (FEP) with a possible immunopathogenic basis. To do this, we designed a data-driven unsupervised machine learning model to cluster a sample of 127 FEP patients and 117 healthy controls (HC), based on the peripheral blood expression levels of 12 psychosis-related immune gene transcripts. To validate the model, we applied a resampling strategy based on the half-splitting of the total sample with random allocation of the cases. Further, we performed a post-hoc univariate analysis to verify the clinical, cognitive, and structural brain correlates of the subgroups identified. The model identified and validated two distinct clusters: 1) a FEP cluster characterized by the high expression of inflammatory and immune-activating genes (IL1B, CCR7, IL12A and CXCR3); 2) a cluster consisting of an equal number of FEP and HC subjects, which did not show a relative over or under expression of any immune marker (balanced subgroup). None of the subgroups was related to specific symptoms dimensions or longitudinal diagnosis of affective vs non-affective psychosis. FEP patients included in the balanced immune subgroup showed a thinning of the left supramarginal and superiorfrontal cortex (FDR-adjusted p-values < 0.05). Our results demonstrated the existence of a FEP patients' subgroup identified by a multivariate pattern of immunomarkers involved in inflammatory activation. This evidence may pave the way to sample stratification in clinical studies aiming to develop diagnostic tools and therapies targeting specific immunopathogenic pathways of psychosis.

The association between victimization and inflammation: A meta-analysis

BACKGROUND

To meta-analyze the existing studies examining the association of childhood and adulthood victimization with inflammation and to explore the moderating variables that affect these relationships.

METHODS

Relevant work published before 28th February 2021 was identified by searching five major databases. We analyzed the cross-sectional data extracted from cross-sectional and longitudinal studies using the random-effects model to estimate the correlation (r) as the pooled effect size and further conducted subgroup analyses and sensitivity analyses.

RESULTS

A total of 37 articles finally met the inclusion criteria, including studies for C-reactive protein (CRP) (k = 23; N_CRP = 11,780), interleukin-6 (IL-6) (k = 31; N_IL-6 = 8943), and tumor necrosis factor-alpha (TNF-α) (k = 14; N_TNF-α = 4125). Overall, victimization has a significantly positive association with inflammation, with a small effect size (r = 0.122). Specifically, effect sizes were the largest for TNF-a (r = 0.152), followed by IL-6 (r = 0.119), and CRP (r = 0.084). Additionally, the effect sizes for victimization against children were r = 0.145 (k = 6) for childhood victimization - childhood inflammation, and r = 0.139 (k = 27) for childhood victimization - adulthood inflammation, which appear to be larger than that of victimization against adults (r = 0.039; k = 2).

LIMITATIONS

Only a small number of studies on adult victimization were included. In addition, we only analyzed the cross-sectional relationship and did not have sufficient data to compare different types of victimization and single vs. multiple victimizations.

CONCLUSIONS

Victimization is associated with a heightened inflammatory response. As victimization against children may have a stronger effect than victimization against adults, prevention of victimization targeting the childhood period may be necessary. Studies with more robust methodologies (i.e., representative, longitudinal, and multi-country designs) are needed to confirm these findings and to unpack the underlying mechanisms.

The association between childhood adversity and the conserved transcriptional response to adversity (CTRA) in sexual minority men

Adverse childhood experiences (ACES) increase risk for mental and physical health disorders in adulthood, particularly in individuals from sexual and ethnic minority groups. The effects of ACES on health may be mediated by the immune system. The exact mechanisms by which an environmental exposure, such as childhood adversity, can affect the immune system are still unknown. The aim of this study was to determine whether early adversity predicts significant changes in the expression of a predefined set of immune-related genes, known as the conserved transcriptional response to adversity (CTRA), in a diverse group of sexual minority men (SMM). Participants included HIV positive and negative males from the mSTUDY. Expression data from 53 CTRA genes were obtained at baseline and 12-month follow-up. Childhood adversity was measured with the 10-item ACES questionnaire. Wilcoxon rank sum and chi-squared tests were used to assess differences in sociodemographic variables and HIV status between exposed (cumulative ACES ≥ 3) and unexposed groups (cumulative ACES ≤ 2). Linear mixed models were used to determine associations between ACES (cumulative score, dichotomous measure and subscales) and CTRA gene expression. There were no differences in age and employment status between the exposed and unexposed groups. A larger number of exposed participants were HIV positive than in the unexposed group (p = 0.03). There were no significant associations between any of the ACES variables and CTRA gene expression. A range of factors may have contributed to this unexpected finding. Further studies are needed to assess the biological effects of ACES in adulthood.

The PMN-MDSC - A key player in glucocorticoid resistance following combined physical and psychosocial trauma

Stress-associated somatic and psychiatric disorders are often linked to non-resolving low-grade inflammation, which is promoted at least in part by glucocorticoid (GC) resistance of distinct immune cell subpopulations. While the monocyte/macrophage compartment was in the focus of many clinical and preclinical studies, the role of myeloid-derived suppressor cells (MDSCs) in stress-associated pathologies and GC resistance is less understood. As GC resistance is a clear risk factor for posttraumatic complications in patients on intensive care, the exact interplay of physical and psychosocial traumatization in the development of GC resistance needs to be further clarified. In the current study we employ the chronic subordinate colony housing (CSC) paradigm, a well-characterized mouse model of chronic psychosocial stress, to study the role of myeloid cells, in particular of MDSCs, in innate immune activation and GC resistance following combined psychosocial and physical (e.g., bite wounds) trauma. Our findings support the hypothesis that stress-induced neutrophils, polymorphonuclear (PMN)-MDSCs and monocytes/monocyte-like (MO)-MDSCs get primed and activated locally in the bone marrow as determined by toll-like receptor (TLR)2 upregulation and increased basal and lipopolysaccharide (LPS)-induced in vitro cell viability. These primed and activated myeloid cells emigrate into the peripheral circulation and subsequently, if CSC is accompanied by significant bite wounding, accumulate in the spleen. Here, PMN-MDSCs and monocytes/MO-MDSCs upregulate TLR4 expression, which exclusively in PMN-MDSCs promotes NF-κB hyperactivation upon LPS-stimulation, thereby exceeding the anti-inflammatory capacities of GCs and resulting in GC resistance.

Interaction effect between childhood abuse and interleukin-1β levels on suicidality in depressed patients

INTRODUCTION

The roles of childhood abuse and interleukin (IL)-1β levels, a representative pro-inflammatory cytokine, in suicidal behavior are unclear. This study investigated the main and interactive effects of childhood abuse and IL-1β levels on suicidal behavior in patients with a depressive disorder before and after pharmacological treatment.

METHODS

At baseline, exposure to self-reported childhood abuse, including emotional, physical, and sexual abuse, before the age of 16 years, and IL-1β levels, were measured in 1,094 outpatients with a depressive disorder, 884 of whom were followed for 1 year. Suicidal behavior was evaluated, including previous suicide attempts (at baseline), suicidal ideation (at baseline and follow-up), and fatal/non-fatal suicide attempts (at follow-up). The main and interaction effects of self-reported childhood abuse and IL-1β level on the four types of suicidal behavior were analyzed using logistic regression after adjusting for covariates.

RESULTS

Individual associations of self-reported childhood abuse were significant only with previous suicidal attempt but not with other suicidal behaviors. There was no significant association of plasma IL-1β level with any suicidal behavior. There were significant interactive associations of self-reported childhood abuse and a high IL-1β level on previous suicide attempts, baseline suicidal ideation, and fatal/non-fatal suicidal attempts during follow-up.

CONCLUSION

Suicidal behavior in patients with a depressive disorder could be influenced by considering the interactive effect of childhood abuse and IL-1β levels. Our study suggests that childhood trauma and biochemical factors play roles in the pathology of suicide in depressed patients.

No evidence for intervention-associated DNA methylation changes in monocytes of patients with posttraumatic stress disorder

DNA methylation patterns can be responsive to environmental influences. This observation has sparked interest in the potential for psychological interventions to influence epigenetic processes. Recent studies have observed correlations between DNA methylation changes and therapy outcome. However, most did not control for changes in cell composition. This study had two aims: first, we sought to replicate therapy-associated changes in DNA methylation of commonly assessed candidate genes in isolated monocytes from 60 female patients with post-traumatic stress disorder (PTSD). Our second, exploratory goal was to identify novel genomic regions with substantial pre-to-post intervention DNA methylation changes by performing whole-genome bisulfite sequencing (WGBS) in two patients with PTSD. Equivalence testing and Bayesian analyses provided evidence against physiologically meaningful intervention-associated DNA methylation changes in monocytes of PTSD patients in commonly investigated target genes (NR3C1, FKBP5, SLC6A4, OXTR). Furthermore, WGBS yielded only a limited set of candidate regions with suggestive evidence of differential DNA methylation pre- to post-therapy. These differential DNA methylation patterns did not prove replicable when investigated in the entire cohort. We conclude that there is no evidence for major, recurrent intervention-associated DNA methylation changes in the investigated genes in monocytes of patients with PTSD.

A comprehensive approach to predicting weight gain and therapy response in psychopharmacologically treated major depressed patients: A cohort study protocol

Background

A subgroup of patients with Major Depressive Disorder shows signs of low-grade inflammation and metabolic abberances, while antidepressants can induce weight gain and subsequent metabolic disorders, and lacking antidepressant response is associated with inflammation.

Objectives

A comprehensive investigation of patient phenotypes and their predictive capability for weight gain and treatment response after psychotropic treatment will be performed. The following factors will be analyzed: inflammatory and metabolic markers, gut microbiome composition, lifestyle indicators (eating behavior, physical activity, chronotype, patient characteristics (childhood adversity among others), and polygenic risk scores.

Methods

Psychiatric inpatients with at least moderate Major Depressive Disorder will be enrolled in a prospective, observational, naturalistic, monocentric study using stratified sampling. Ethical approval was obtained. Primary outcomes at 4 weeks will be percent weight change and symptom score change on the Montgomery Asberg Depression Rating Scale. Both outcomes will also be binarized into clinically relevant outcomes at 5% weight gain and 50% symptom score reduction. Predictors for weight gain and treatment response will be tested using multiple hierachical regression for continuous outcomes, and multiple binary logistic regression for binarized outcomes. Psychotropic premedication, current medication, eating behavior, baseline BMI, age, and sex will be included as covariates. Further, a comprehensive analysis will be carried out using machine learning. Polygenic risk scores will be added in a second step to estimate the additional variance explained by genetic markers. Sample size calculation yielded a total amount of N = 171 subjects.

Discussion

Patient and physician expectancies regarding the primary outcomes and non-random sampling may affect internal validity and external validity, respectively. Through the prospective and naturalistic design, results will gain relevance to clinical practice. Examining the predictive value of patient profiles for weight gain and treatment response during pharmacotherapy will allow for targeted adjustments before and concomitantly to the start of treatment.

Associations of three major physiological stress systems with suicidal ideation and suicide attempts in patients with a depressive and/or anxiety disorder

BACKGROUND

People with depressive and/or anxiety disorders are at increased risk of suicidal ideation and suicide attempts, but biological correlates signaling such risk remain unclear. Independent and cumulative dysregulations in physiological stress systems, in particular the hypothalamic-pituitaryadrenal axis (HPA-axis), immune-inflammatory system, and autonomous nervous system (ANS), may contribute to this risk. However, findings have either been heterogeneous or absent thus far.

METHODS

Associations between individual markers and cumulative indices of the HPA-axis (cortisol awakening response and evening cortisol), immune-inflammatory system (C-reactive protein, interleukin-6 (IL-6), and tumor necrosis factor-α), and the ANS (heart rate, respiratory sinus arrhythmia, and pre-ejection period) and the outcomes no suicide ideation with suicide attempt (SI-SA+), suicide ideation without suicide attempt (SI+SA-) and suicide ideation with suicide attempt (SI+SA+) were investigated in 1749 persons with depressive and/or anxiety disorders from the Netherlands Study of Depression and Anxiety (NESDA).

RESULTS

High levels of CRP and IL-6 were associated with SI-SA+ and SI+SA+ respectively when compared to non-suicidal patients after adjusting for confounders and multiple testing. Also, cumulative immune-inflammatory dysregulations were positively associated with SI+SA+, suggesting a dose-response effect. No significant associations were found between HPA-axis or ANS indicators and suicide-outcomes and between immune-inflammatory system markers or cumulative stress system dysregulations and SI+SA-.

CONCLUSION

Although stress system markers could not differentiate between SI+SA- and non-suicidal patients, findings indicate that dysregulations of individual and cumulative immune-inflammatory markers are associated with suicide attempts in depressive and/or anxiety patients. Thus, immune-inflammatory system dysregulation may be involved in the pathophysiology of suicidal behavior, supporting further examination of the effects of anti-inflammatory interventions on suicidality.

P2X7 Receptor-Related Genetic Mouse Models – Tools for Translational Research in Psychiatry

Depression is a common psychiatric disorder and the leading cause of disability worldwide. Although treatments are available, only about 60% of treated patients experience a significant improvement in disease symptoms. Numerous clinical and rodent studies have identified the purinergic P2X7 receptor (P2X7R) as one of the genetic factors potentially contributing to the disease risk. In this respect, genetically engineered mouse models targeting the P2X7R have become increasingly important in studying designated immunological features and subtypes of depression in vivo. This review provides an overview of the P2X7R -related mouse lines currently available for translational psychiatric research and discusses their strengths, weaknesses, and potentials.

Inflammation biomarkers in suicide attempts and their relation to abuse, global functioning and cognition

OBJECTIVES

To explore the link between cytokines and suicide attempts and their relationship with the psychological aspects of this complex multifactorial phenomenon.

METHODS

96 participants, including 20 patients with a recent suicide attempt and diagnosis of Major Depression Disorder (MDD), 33 MDD patients with a lifetime history of suicide attempt, 23 non-attempter MDD patients, and 20 healthy controls underwent an assessment on depressive symptoms, global functioning, aggressive behaviour, presence of abuse and attention performance. Additionally, all participants had a blood extraction for IL-2, IL2-R, IL-4, IL-6, and TNF-α plasma levels analysis.

RESULTS

IL-6 levels were significantly different across groups (F(3,89)=3.690; p = 0.015), with higher concentrations in both recent (p = 0.04) and distant (p = 0.015) attempt in comparison to MDD non-attempters. IL-6 was associated with adult physical abuse (B = 2.591; p = 0.021), lower global functioning score (B = -0.512; p = 0.011), and poorer performance on attention (B = -0.897; p = 0.011).

CONCLUSIONS

Recent and distant suicidal behaviour is associated with elevated IL-6 levels, which may be influenced by stressful and traumatic experiences. Elevated concentrations of IL-6 could have a negative impact on attention, increasing suicide risk. More research is needed to clarify the role of cytokines in suicide-related features to explore novel treatments and more effective preventive interventions.

Navigating a complex landscape - A review of the relationship between inflammation and childhood trauma and the potential roles in the expression of symptoms of depression

Recent research has explored associations between depression and inflammation, and interactions between childhood trauma and both factors. Major Depressive Disorder (MDD) is a prevalent issue and with one third of patients not responding to standard antidepressant treatments, it is crucial to develop our understanding. While research delves into the complex landscape of the roles of both childhood trauma and inflammation in depression, it is customary for literature to explore effects on presence of depression. However, understanding if childhood trauma and inflammation may be affecting the symptom profiles of depression and what implications this may have, is lacking.

T cell responses in depressed mice induced by chronic unpredictable mild stress

BACKGROUND

The relationship between depression and adaptive immunity has gradually attracted increasing attentions. However, no consistent conclusions have been drawn about alterations in adaptive immunity in depression.

METHODS

Eight-week-old weight-matched male C57BL/6 mice were randomly divided into a chronic unpredictable mild stress (CUMS) model group and a control group, with twelve mice in each group. After 8-week CUMS modeling duration and depressive behavioral tests, T cell responses were evaluated at the cell, cytokine, and cell-specific transcription factor levels. Lymphocytes in the spleen were detected by flow cytometry; serum cytokines were assessed by enzyme-linked immunosorbent assays; expression levels of cytokines and cell-specific transcription factors in the hippocampus were determined by quantitative PCR.

RESULTS

CUMS exposure induced depression-like behaviors with decreased sucrose preference and longer immobility time in the tail suspension test and forced swim test. The CUMS group had a lower proportion of CD4+T cells than the control group. A decreased number of T helper 17 (Th17) cells in the spleen and down regulated serum interleukin (IL)-17 and hippocampal retinoid-related orphan receptor-γt levels were detected in the CUMS group. Depressed mice in the CUMS group showed increases in serum IL-1β and IL-6 and hippocampal IL-6 and IL-4 levels.

LIMITATION

The study was based on a mouse model. Further studies are needed to determine whether the results are applicable to patients with depression.

CONCLUSION

CUMS exposure can induce depression-like behaviors and decrease Th17 cell counts.

Genetic variations related to inflammation in suicidal ideation and behavior: A systematic review

BACKGROUND/OBJECTIVES

Immune-inflammatory changes have been found in all types of suicidal ideation and behavior (SIB), independently of associated mental disorders. Since several Single Nucleotide Polymorphisms (SNPs) affect the function of inflammation-related genes, we searched the literature for genetic variations potentially altering inflammatory processes in SIB.

METHODS

We included studies that looked for associations between SIB and SNPs in genes related to inflammatory processes. Case reports, literature reviews, and animal studies were excluded. Articles were retrieved from PubMed and PsycINFO databases, Google Scholar and GreySource Index until September 17th, 2022. Quality was assessed using Q-Genie.

RESULTS

We analyzed 32 studies. SIB has been associated with eighteen SNPs located in genes encoding for interleukin-8 (rs4073), C-reactive protein (rs1130864), tumor necrosis factor α (rs1800629, rs361525, and rs1099724), tumor necrosis factor receptor 2 (rs1061622), transforming growth factor β-1 (rs1982073), acid phosphatase 1 (rs7419262, rs300774), interleukin-10 (rs1800896), interferon γ (rs2430561), amino-carboxy muconate semialdehyde decarboxylase (rs2121337), interleukin 7 (rs10448044, rs10448042), macrophage migration inhibitory factor (rs755622), interleukin 1-α (rs1800587), and interleukin 1-β (rs1143634 and rs16944. A genome-wide association study reported one association at the threshold of significance with the rs300774 SNP, located in the 2p25 region containing ACP1 gene.

DISCUSSION

The studies included were methodologically and clinically diverse and of moderate quality. Their findings suggest that some inflammation-related SNPs could increase the likelihood of SIB but the evidence to date is insufficient. Further research using gene-gene (GxG) and gene-environment (GxE) approaches is warranted.

SYSTEMATIC REVIEW REGISTRATION

[https://www.crd.york.ac.uk], identifier [CRD42022296310].

Coexpression of Gene Transcripts with Monoamine Oxidase A Quantified by Human In Vivo Positron Emission Tomography

The monoamine oxidase A (MAO-A) is integral to monoamine metabolism and is thus relevant to the pathophysiology of various neuropsychiatric disorders; however, associated gene-enzyme relations are not well understood. This study aimed to unveil genes coexpressed with MAO-A. Therefore, 18 179 mRNA expression maps (based on the Allen Human Brain Atlas) were correlated with the cerebral distribution volume (VT) of MAO-A assessed in 36 healthy subjects (mean age ± standard deviation: 32.9 ± 8.8 years, 18 female) using [11C]harmine positron emission tomography scans. Coexpression analysis was based on Spearman's ρ, over-representation tests on Fisher's exact test with false discovery rate (FDR) correction. The analysis revealed 35 genes in cortex (including B-cell translocation gene family, member 3, implicated in neuroinflammation) and 247 genes in subcortex (including kallikrein-related peptidase 10, implicated in Alzheimer's disease). Significantly over-represented Gene Ontology terms included "neuron development", "neuron differentiation", and "cell-cell signaling" as well as "axon" and "neuron projection". In vivo MAO-A enzyme distribution and MAOA expression did not correlate in cortical areas (ρ = 0.08) while correlation was found in subcortical areas (ρ = 0.52), suggesting influences of region-specific post-transcriptional and -translational modifications. The herein reported information could contribute to guide future genetic studies, deepen the understanding of associated pathomechanisms and assist in the pursuit of novel therapeutic targets.

Monocyte mitochondrial dysfunction, inflammaging, and inflammatory pyroptosis in major depression

BACKGROUND

The macrophage theory of depression states that macrophages play an important role in Major Depressive Disorder (MDD).

METHODS

MDD patients (N = 140) and healthy controls (N = 120) participated in a cross-sectional study investigating the expression of apoptosis/growth and lipid/cholesterol pathway genes (BAX, BCL10, EGR1, EGR2, HB-EGF, NR1H3, ABCA1, ABCG1, MVK, CD163, HMOX1) in monocytes (macrophage/microglia precursors). Gene expressions were correlated to a set of previously determined and reported inflammation-regulating genes and analyzed with respect to various clinical parameters.

RESULTS

MDD monocytes showed an overexpression of the apoptosis/growth/cholesterol and the TNF genes forming an inter-correlating gene cluster (cluster 3) separate from the previously described inflammation-related gene clusters (containing IL1 and IL6). While upregulation of monocyte gene cluster 3 was a hallmark of monocytes of all MDD patients, upregulation of the inflammation-related clusters was confirmed to be found only in the monocytes of patients with childhood adversity. The latter group also showed a downregulation of the cholesterol metabolism gene MVK, which is known to play an important role in trained immunity and proneness to inflammation.

CONCLUSIONS

The upregulation of cluster 3 genes in monocytes of all MDD patients suggests a premature aging of the cells, i.e. mitochondrial apoptotic dysfunction and TNF "inflammaging", as a general feature of MDD. The overexpression of the IL-1/IL-6 containing inflammation clusters and the downregulation of MVK in monocytes of patients with childhood adversity indicates a shift in this condition to a more severe inflammation form (pyroptosis) of the cells, additional to the signs of premature aging and inflammaging.

Evaluation of the effects of altitude on biological signatures of inflammation and anxiety- and depressive-like behavioral responses

Over sixteen million people suffer from a depressive episode annually in the United States, with females affected at twice the rate of males. Little is known about the effects of exposure to high altitude on the risk of development of major depressive disorder, despite reports of higher suicide rates at higher altitudes. We hypothesize that exposure to hypobaric hypoxia at high altitude increases endophenotypes of self-directed suicidal violence, including biological signatures of chronic inflammation and vulnerability to anxiety-like and depressive-like behavioral responses in a sex-specific manner. Biological signatures of inflammation, including granulocyte:lymphocyte ratios, monocyte cell counts, and monocyte:lymphocyte ratios were assessed using complete blood count data, anhedonia, and anxiety- and depressive-like behavioral responses were evaluated. We assessed biological signatures of inflammation and behavioral responses in the open-field test, sucrose preference test, and modified Porsolt forced swim test in young adult male and female Long-Evans and Sprague Dawley rats. All tests were conducted near sea level (374 ft [114 m] elevation) and at moderate-high altitude (5430 ft [1655 m] elevation) during acclimation periods of one, two, three, four, and five weeks following shipment from a sea level animal breeding facility (N = 320, n = 8 per group). Exposure to moderate-high altitude induced a biological signature of increased inflammation, as evidenced by main effects of altitude for: 1) increased granulocyte:lymphocyte ratio; 2) increased count and relative abundance of circulating monocytes; and 3) increased monocyte:lymphocyte ratios. Exposure to moderate-high altitude also increased anhedonia as assessed in the sucrose preference test in both male and female rats, when data were collapsed across strain and time. Among male and female Long Evans rats, exposure to moderate-high altitude increased immobility in the forced swim test, without changing anxiety-like behaviors in the open-field test. Finally, granulocyte:lymphocyte ratios were correlated with anhedonia in the sucrose preference test. These data are consistent with the hypothesis that hypobaric hypoxia at moderate-high altitude induces persistent endophenotypes of self-directed suicidal violence including biological signatures of inflammation, anhedonia, and depressive-like behavioral responses.

Biological, Psychological, and Social Determinants of Depression: A Review of Recent Literature

Depression is one of the leading causes of disability, and, if left unmanaged, it can increase the risk for suicide. The evidence base on the determinants of depression is fragmented, which makes the interpretation of the results across studies difficult. The objective of this study is to conduct a thorough synthesis of the literature assessing the biological, psychological, and social determinants of depression in order to piece together the puzzle of the key factors that are related to this condition. Titles and abstracts published between 2017 and 2020 were identified in PubMed, as well as Medline, Scopus, and PsycInfo. Key words relating to biological, social, and psychological determinants as well as depression were applied to the databases, and the screening and data charting of the documents took place. We included 470 documents in this literature review. The findings showed that there are a plethora of risk and protective factors (relating to biological, psychological, and social determinants) that are related to depression; these determinants are interlinked and influence depression outcomes through a web of causation. In this paper, we describe and present the vast, fragmented, and complex literature related to this topic. This review may be used to guide practice, public health efforts, policy, and research related to mental health and, specifically, depression.

Rapidly Growing Mycobacterium Species: The Long and Winding Road from Tuberculosis Vaccines to Potent Stress-Resilience Agents

Inflammatory diseases and stressor-related psychiatric disorders, for which inflammation is a risk factor, are increasing in modern Western societies. Recent studies suggest that immunoregulatory approaches are a promising tool in reducing the risk of suffering from such disorders. Specifically, the environmental saprophyte Mycobacterium vaccae National Collection of Type Cultures (NCTC) 11659 has recently gained attention for the prevention and treatment of stress-related psychiatric disorders. However, effective use requires a sophisticated understanding of the effects of M. vaccae NCTC 11659 and related rapidly growing mycobacteria (RGMs) on microbiome–gut–immune–brain interactions. This historical narrative review is intended as a first step in exploring these mechanisms and provides an overview of preclinical and clinical studies on M. vaccae NCTC 11659 and related RGMs. The overall objective of this review article is to increase the comprehension of, and interest in, the mechanisms through which M. vaccae NCTC 11659 and related RGMs promote stress resilience, with the intention of fostering novel clinical strategies for the prevention and treatment of stressor-related disorders.

The genetic basis of major depression

Major depressive disorder (MDD) is a common, debilitating, phenotypically heterogeneous disorder with heritability ranges from 30% to 50%. Compared to other psychiatric disorders, its high prevalence, moderate heritability, and strong polygenicity have posed major challenges for gene-mapping in MDD. Studies of common genetic variation in MDD, driven by large international collaborations such as the Psychiatric Genomics Consortium, have confirmed the highly polygenic nature of the disorder and implicated over 100 genetic risk loci to date. Rare copy number variants associated with MDD risk were also recently identified. The goal of this review is to present a broad picture of our current understanding of the epidemiology, genetic epidemiology, molecular genetics, and gene-environment interplay in MDD. Insights into the impact of genetic factors on the aetiology of this complex disorder hold great promise for improving clinical care.

Activation and deactivation steps in the tryptophan breakdown pathway in major depressive disorder: A link to the monocyte inflammatory state of patients

It is unclear how the tryptophan (TRP) breakdown pathway relates to the activated inflammatory state of patients with major depressive disorder (MDD). We determined in two different cohorts of patients with MDD (n = 281) and healthy controls (HCs) (n = 206) collected for the EU-MOODINFLAME project: We then correlated outcomes to each other, and to the clinical characteristics of patients. Both cohorts of patients differed clinically; patients of the Munich cohort (n = 50) were less overweight, less medicated, were less in the current episode and showed a higher HAM-D 17 score as compared with patients of the Muenster cohort (n = 231). An increased expression of ICCGs was found in the circulating monocytes of patients of both cohorts; this was in particular evident in the Munich cohort. In contrast, ISGs monocyte expression levels tended to be reduced (both cohorts). TRP serum levels were linked to the pro-inflammatory (ICCGs) monocyte state of patients; a decrease in TRP serum levels was found in the Munich cohort; TRP levels correlated negatively to patient's HAM-D 17 score. Contrary to what expected, KYN serum levels were not increased in patients (both cohorts); and an increased KYN/TRP ratio was only found in the Munich patients (who showed the lowest TRP serum levels). IDO-1 monocyte expression levels were decreased in patients (both cohorts) and negatively associated to their pro-inflammatory (ICCGs) monocyte state. Thus, a depletion of TRP via an ICCGs-inflammatory IDO activation is not likely in MDD. Downstream from KYN, and regarding compounds influencing glutamate receptors (GR), reduced serum levels of KYNA (NMDA-R antagonist), 3-HK (NMDA-R agonist), and XA (mGlu2/3 agonist) were found in patients of both cohorts; PIC serum levels (NMDA-R antagonist) were increased in patients of both cohorts. Reduced QUIN serum levels (NMDA-R agonist) were found in patients of the Muenster cohort,only. 3-HK levels correlated to the monocyte inflammatory ICCG state of patients. The ultimate effect on brain glutamate receptor triggering of this altered equilibrium between peripheral agonists and antagonists remains to be elucidated.

Efficacy of Sertraline Plus Placebo or Add-On Celecoxib in Major Depressive Disorder: Macrophage Migration Inhibitory Factor as a Promising Biomarker for Remission After Sertraline-Results From a Randomized Controlled Clinical Trial

Introduction: Previous research delivers strong indications that inflammatory activation leads to treatment resistance in a subgroup of patients with Major Depressive Disorder (MDD). Thus, tailored interventions are needed. The present study aimed to find potential biomarkers that may enable patients to be stratified according to immune activation. Methods: A phase IIa randomized placebo-controlled trial was performed to assess levels of inflammatory compounds in responders/remitters and non-responders/non-remitters to sertraline plus celecoxib (n = 20) and sertraline plus placebo (n = 23). Levels of macrophage migration inhibitory factor, neopterin, and tumor necrosis factor alpha were determined by enzyme-linked immunosorbent assay; response and remission were measured by reduction of the Montgomery Åsberg Depression Rating Scale score. Results: Both treatment groups showed a significant decline in depression symptoms, but no difference was found between groups. A clear pattern emerged only for macrophage migration inhibitory factor: placebo remitters showed significantly lower baseline levels than non-remitters (a similar trend was seen in responders and non-responders) while celecoxib responders showed a trend for higher baseline levels than non-responders. Conclusion: Small subsample sizes are a notable limitation, wherefore results are preliminary. However, the present study provides novel insights by suggesting macrophage migration inhibitory factor as a promising biomarker for treatment choice. The trial was registered in EU Clinical Trials Register (EU-CTR): https://www.clinicaltrialsregister.eu/ctr-search/trial/2009-011990-34/DE, EudraCT-No.: 2009-011990-34.

Inflamed Mind: Multiple Genetic Variants of IL6 Influence Suicide Risk Phenotypes in Interaction With Early and Recent Adversities in a Linkage Disequilibrium-Based Clumping Analysis

Background: Understanding and predicting suicide remains a challenge, and a recent paradigm shift regarding the complex relationship between the immune system and the brain brought attention to the involvement of inflammation in neuropsychiatric conditions including suicide. Among cytokines, IL-6 has been most frequently implicated in suicide, yet only a few candidate gene studies and without considering the effect of stress investigated the role of IL6 in suicidal behaviour. Our study aimed to investigate the association of IL6 variation with a linkage disequilibrium-based clumping method in interaction with childhood adversities and recent stress on manifestations along the suicide spectrum. Methods: One thousand seven hundred and sixty-two participants provided information on previous suicide attempts, current suicidal ideation, thoughts of death, and hopelessness, and were genotyped for 186 variants in IL6. Early childhood adversities were recorded with an instrument adapted from the Childhood Trauma Questionnaire, recent life events were registered using the List of Threatening Life Events. Following a 3-step quality control, logistic and linear regression models were run to explore the effect of genotype and gene-environment interactions on suicide phenotypes. All regression models were followed by a clumping process based on empirical estimates of linkage disequilibrium between clumps of intercorrelated SNPs. Interaction effects of distinct types of recent life events were also analysed. Results: No clumps with significant main effects emerged, but we identified several clumps significantly interacting with childhood adversities on lifetime suicide attempts, current suicidal ideation, and current thoughts of death. We also identified clumps significantly interacting with recent negative life events on current suicidal ideation. We reported no clumps with significant effect on hopelessness either as a main effect or in interaction with childhood adversities or recent stress. Conclusion: We identified variant clumps in IL6 influencing suicidal behaviour, but only in interaction with childhood or recent adversities. Our results may bring us a step further in understanding the role of neuroinflammation and specifically of IL-6 in suicide, towards identifying novel biological markers of suicidal behaviour especially in those exposed to stressful experiences, and to fostering the adaptation of a new paradigm and identifying novel approaches and targets in the treatment of suicidal behaviour.