Low plasma vascular endothelial growth factor (VEGF) associated with completed suicide

Association between peripheral plasma cytokine levels and suicidal ideation in first-episode, drug-naïve major depressive disorder

BACKGROUND

Inflammatory processes could potentially impact both mood and suicide risk, however, the relationship between cytokines and suicidal ideation remains unclear. This study aimed to investigate the association between plasma levels of cytokines and suicidal ideation in population with major depressive disorders (MDD).

METHODS

A cross-sectional study was performed to assess the peripheral plasma levels of interleukin-1β (IL-1β), IL-2, IL-6, IL-8, IL-10 and tumor necrosis factor-α (TNF-α) in 88 Chinese Han first-episode drug-naïve MDD patients. Suicidal ideation in the past week were identified using the Beck Scale for Suicide Ideation-Chinese Version (BSI-CV). The Hamilton Depression Rating Scale-17 (HAMD-17), the Hamilton Anxiety Rating Scale-14 (HAMA-14) and the Childhood Trauma Questionnaire (CTQ) was used to assess depression, anxiety and childhood trauma. Multivariable logistic regression models were used to estimate the association between cytokines and suicidal ideation. Interaction and stratified analyses were conducted according to age, sex, marital status, education, smoking status, BMI and physical activity.

RESULTS

Among the 88 participants, 42 individuals (47.7%) reported suicidal ideation within the past week. In the fully adjusted model, a statistically significant trend was observed in the association between IL-2 level and suicidal ideation (OR: 1.40, 95% CI: 1.00-1.97). The stratified analysis showed a statistically significant association between IL-6 level and suicidal ideation among younger people (OR: 1.17, 95% CI: 1.01-1.36) and a significant positive association between IL-8 (OR: 1.59, 95% CI: 1.03-2.44) and IL-10 (OR: 2.51, 95% CI: 1.27-4.96) levels and suicide ideation among higher educated populations.

LIMITATIONS

The cross-sectional design, residual confounding effects and small sample size CONCLUSION: Our findings indicate a significant positive association between plasma IL-2 level and suicidal ideation in MDD patients. IL-2 has the potential to be a biomarker of suicidal ideation in patients with depression.

Molecular Changes Associated with Suicide

Suicide is a serious global public health problem, with a worrying recent increase in suicide rates in both adolescent and adult populations. However, it is essential to recognize that suicide is preventable. A myriad of factors contributes to an individual's vulnerability to suicide. These factors include various potential causes, from psychiatric disorders to genetic and epigenetic alterations. These changes can induce dysfunctions in crucial systems such as the serotonergic, cannabinoid, and hypothalamic-pituitary-adrenal axes. In addition, early life experiences of abuse can profoundly impact an individual's ability to cope with stress, ultimately leading to changes in the inflammatory system, which is a significant risk factor for suicidal behavior. Thus, it is clear that suicidal behavior may result from a confluence of multiple factors. This review examines the primary risk factors associated with suicidal behavior, including psychiatric disorders, early life adversities, and epigenetic modifications. Our goal is to elucidate the molecular changes at the genetic, epigenetic, and molecular levels in the brains of individuals who have taken their own lives and in the plasma and peripheral mononuclear cells of suicide attempters and how these changes may serve as predisposing factors for suicidal tendencies.

Levels of IL-6 are Associated with Lifetime Attempted Suicide in Alcohol Use Disorder Patients

Background

Patients with alcohol use disorder (AUD) have an increased risk of suicide. Neuroimmunological measures, such as cytokines, are shown to deviate in people with attempted suicide. Few studies have investigated this among AUD patients.

Patients and Methods

One-hundred and fourteen patients undergoing residential treatment for AUD were interviewed on lifetime suicide attempts (SA) along with several other background variables and clinical characteristics. Serum blood samples were drawn for analysis of cytokines.

Results

Thirty-one patients (27%) reported at least one SA. These patients had more symptoms of current affective disorders and more severe dependence. In bivariate analysis only IL-6 and IL-10 appeared to be associated with lifetime SA but without reaching statistical significance. In multivariate linear regression, adjusting for sex, nicotine use, somatic illness, and the use of anti-inflammatory drugs, IL-6 was associated to SA (p = 0.033).

Conclusion

The cytokine IL-6 has repeatedly been found to be associated with suicidality. The present study concurs with this role of IL-6 in a naturalistic observational study of AUD patients.

Vascular Endothelial Growth Factor Polymorphism rs699947 Is Associated with Neurostructural Phenotypes in Youth with Bipolar Disorder

Background: Vascular endothelial growth factor (VEGF) may be relevant to bipolar disorder (BD) and brain structure. We evaluated VEGF rs699947 single-nucleotide polymorphism in relation to structural neuroimaging phenotypes in youth BD. Methods: We collected 3 T anatomical magnetic resonance images from 154 youth (79 BD and 75 healthy control [HC]) genotyped for VEGF rs699947. The participants were age (BD = 17.28 ± 1.40 and HC = 17.01 ± 1.83, t = -1.02, p = 0.31) and sex (BD = 63.3% females and HC = 52.0% females, χ2 = 2.01, p = 0.16) matched. Cortical thickness, surface area (SA), and volume were examined by region-of-interest (ROI) and vertex-wise analyses using general linear models (GLMs). ROI investigations selected for the prefrontal cortex (PFC), amygdala, and hippocampus. Vertex-wise analyses controlled for age, sex, and intracranial volume. Results: ROI results found lower PFC SA (p = 0.003, ηp2 = 0.06) and volume (p = 0.04, ηp2 = 0.03) in BD and a main effect of rs699947 on hippocampal volume (p = 0.03, ηp2 = 0.05). The latter two findings did not survive multiple comparisons. Vertex-wise analyses found rs699947 main effects on left postcentral gyrus volume (p < 0.001), right rostral anterior cingulate SA (p = 0.004), and right superior temporal gyrus thickness (p = 0.004). There were significant diagnosis-by-genotype interactions in the left superior temporal, left caudal middle frontal, left superior frontal, right fusiform, and right lingual gyri, and the left insular cortex. Posthoc analyses revealed the AA allele was associated with larger brain structures among HC, but smaller brain structures in BD for most clusters. Conclusions: Overall, we found preliminary evidence of divergent associations between BD and HC youth in terms of neurostructural correlates of VEGF rs699947 encompassing highly relevant frontotemporal regions.

Multiple serum biomarkers for predicting suicidal behaviours in depressive patients receiving pharmacotherapy

BACKGROUND

Predictive values of multiple serum biomarkers for suicidal behaviours (SBs) have rarely been tested. This study sought to evaluate and develop a panel of multiple serum biomarkers for predicting SBs in outpatients receiving a 12-month pharmacotherapy programme for depressive disorders.

METHODS

At baseline, 14 serum biomarkers and socio-demographic/clinical characteristics including previous suicidal attempt and present suicidal severity were evaluated in 1094 patients with depressive disorders without a bipolar diagnosis. Of these, 884 were followed for increased suicidal severity and fatal/non-fatal suicide attempt outcomes over a 12-month treatment period. Individual and combined effects of serum biomarkers on these two prospective SBs were estimated using logistic regression analysis after adjustment for relevant covariates.

RESULTS

Increased suicidal severity and fatal/non-fatal suicide attempt during the 12-month pharmacotherapy were present in 155 (17.5%) and 38 (4.3%) participants, respectively. Combined cortisol, total cholesterol, and folate serum biomarkers predicted fatal/non-fatal suicide attempt, and these with interleukin-1 beta and homocysteine additionally predicted increased suicidal severity, with clear gradients robust to adjustment (p values < 0.001).

CONCLUSIONS

Application of multiple serum biomarkers could considerably improve the predictability of SBs during the outpatient treatment of depressive disorders, potentially highlighting the need for more frequent monitoring and risk appraisal.

Fight the Fire: Association of Cytokine Genomic Markers and Suicidal Behavior May Pave the Way for Future Therapies

The fight against suicide is highly challenging as it may be one of the most complex and, at the same time, most threatening among all psychiatric phenomena. In spite of its huge impact, and despite advances in neurobiology research, understanding and predicting suicide remains a major challenge for both researchers and clinicians. To be able to identify those patients who are likely to engage in suicidal behaviors and identify suicide risk in a reliable and timely manner, we need more specific, novel biological and genetic markers/indicators to develop better screening and diagnostic methods, and in the next step to utilize these molecules as intervention targets. One such potential novel approach is offered by our increasing understanding of the involvement of neuroinflammation based on multiple observations of increased proinflammatory states underlying various psychiatric disorders, including suicidal behavior. The present paper overviews our existing understanding of the association between suicide and inflammation, including peripheral and central biomarkers, genetic and genomic markers, and our current knowledge of intervention in suicide risk using treatments influencing inflammation; also overviewing the next steps to be taken and obstacles to be overcome before we can utilize cytokines in the treatment of suicidal behavior.

Neurotrophic basis to the pathogenesis of depression and phytotherapy

Depression is a major neuropsychiatric disease that considerably impacts individuals’ psychosocial function and life quality. Neurotrophic factors are now connected to the pathogenesis of depression, while the definitive neurotrophic basis remains elusive. Besides, phytotherapy is alternative to conventional antidepressants that may minimize undesirable adverse reactions. Thus, further research into the interaction between neurotrophic factors and depression and phytochemicals that repair neurotrophic factors deficit is highly required. This review highlighted the implication of neurotrophic factors in depression, with a focus on the brain-derived neurotrophic factor (BDNF), glial cell line-derived neurotrophic factor (GDNF), vascular endothelial growth factor (VEGF), and nerve growth factor (NGF), and detailed the antidepressant activities of various phytochemicals targeting neurotrophic factors. Additionally, we presented future opportunities for novel diagnostic and therapeutic strategies for depression and provided solutions to challenges in this area to accelerate the clinical translation of neurotrophic factors for the treatment of depression.

The Role of Inflammation in the Pathophysiology of Depression and Suicidal Behavior: Implications for Treatment

Depression and suicidal behavior are 2 complex psychiatric conditions of significant public health concerns due to their debilitating nature. The need to enhance contemporary treatments and preventative approaches for these illnesses not only calls for distillation of current views on their pathogenesis but also provides an impetus for further elucidation of their novel etiological determinants. In this regard, inflammation has recently been recognized as a potentially important contributor to the development of depression and suicidal behavior. This review highlights key evidence that supports the presence of dysregulated neurometabolic and immunologic signaling and abnormal interaction with microbial species as putative etiological hallmarks of inflammation in depression as well as their contribution to the development of suicidal behavior. Furthermore, therapeutic insights addressing candidate mechanisms of pathological inflammation in these disorders are proposed.

Suicide and Inflammation

Suicide is a leading cause of death worldwide. Although the neurobiological dysfunction underlying suicidal behavior remains unclear, recent work suggests that the immune system may play a role in the pathophysiology of suicide. In this chapter, we discuss a nascent body of literature suggesting that peripheral and central nervous systems (CNS) inflammation are associated with suicidal behavior. Because early-life stress is a major risk factor for suicidal behavior and is also associated with immune dysregulation, we hypothesize that such immune dysregulation may be the mechanism by which childhood maltreatment leads to an increased risk of suicidal behavior and suicide. Targeting inflammatory processes may be a novel treatment strategy, especially in populations that have experienced childhood trauma and exhibit elevated inflammation. Future work should directly test the hypothesis that reducing inflammation would result in a reduction in suicidal behavior.

Inflammation, cognitive dysfunction, and suicidal ideation among patients with major depression

BACKGROUND

Dysregulated proinflammatory cytokines have been shown to be associated with suicidal behavior. Cognitive deficits in working memory and inhibitory control have been demonstrated in depressed patients and people with suicidal ideation (SI). However, the association between proinflammatory cytokines, SI, and cognitive deficits in patients with major depressive disorder (MDD) remains unclear.

METHODS

A total of 77 patients with MDD and age-/sex-matched 60 healthy individuals were recruited. MDD patients were divided into two groups: with SI (n = 36) and no SI (n = 41). SI was defined by a score of ≥2 in item 3 of the 17-item Hamilton Rating Scale for Depression. Levels of proinflammatory cytokines, including soluble interleukin-6 receptor, soluble tumor necrosis factor-α receptor type 1, and C-reactive protein (CRP), were measured, and cognitive function was assessed using 2-back task and Go/No-Go task.

RESULTS

Patients with SI had higher levels of CRP than those without SI and controls (P = .007). CRP was positively associated with SI (β = 0.21, P = .037), independent of cognitive function and depressive symptoms. Furthermore, SI was associated with cognitive deficits in working memory and inhibitory control after adjusting for confounding factors (P < .05).

CONCLUSION

Our findings suggest that higher levels of serum CRP and deficits in working memory and inhibitory control may be associated with higher SI among patients with MDD.

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.

Neurobiological Highlights of Cognitive Impairment in Psychiatric Disorders

This review is focused on several psychiatric disorders in which cognitive impairment is a major component of the disease, influencing life quality. There are plenty of data proving that cognitive impairment accompanies and even underlies some psychiatric disorders. In addition, sources provide information on the biological background of cognitive problems associated with mental illness. This scientific review aims to summarize the current knowledge about neurobiological mechanisms of cognitive impairment in people with schizophrenia, depression, mild cognitive impairment and dementia (including Alzheimer's disease).The review provides data about the prevalence of cognitive impairment in people with mental illness and associated biological markers.

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].

Plasma VEGF Concentrations and Ketamine's Effects on Suicidal Ideation in Depression With Suicidal Ideation

OBJECTIVES

Accumulating evidence supports a role for vascular endothelial growth factor (VEGF) in the pathogenesis of depression, but its relationship with the antisuicidal effects of ketamine is not clear. Our objective was to determine whether there was an association between the plasma VEGF (pVEGF) concentrations and the antisuicidal response to serial ketamine infusions.

METHODS

Six ketamine infusions (0.5 mg/kg) over a 12-day period were administered to sixty depressed individuals suffering from suicidal ideation. The Hamilton Depression Rating Scale (HAMD) suicide item, the Montgomery-Åsberg Depression Rating Scale (MADRS) suicide item, and the Beck Scale for Suicide Ideation (SSI-part I) were used to assess suicidal ideation at baseline, 1 day after the first infusion (day 1), 1 day following the last infusion (day 13), and again 2 weeks post-infusion (day 26). For this purpose, plasma was obtained at baseline, day 13 and 26.

RESULTS

The rates of antisuicidal response to ketamine were 61.7% (37/60), 81.7% (49/60), and 73.3% (44/60) at days 1, 13, and 26, respectively. The linear mixed model revealed significant time effects on suicidal ideation and pVEGF concentrations over time (all Ps < 0.05). Antisuicidal responders did not have significantly altered pVEGF concentrations compared with non-responders on day 13 and day 26 (all Ps > 0.05). No significant correlation was found between the baseline pVEGF concentration and suicidal ideation as measured by the SSI part 1, HAMD suicide item and MADRS suicide item on days 1, 13, and 26 (all ps > 0.05).

CONCLUSION

This preliminary finding does not support a role for VEGF in the antisuicidal effects of serial ketamine treatments in individuals with depression and suicidal ideation. Further research is needed to confirm and expand these findings.

Choroid plexus enlargement is associated with neuroinflammation and reduction of blood brain barrier permeability in depression

BACKGROUND

Recent studies have shown that choroid plexuses (CP) may be involved in the neuro-immune axes, playing a role in the interaction between the central and peripheral inflammation. Here we aimed to investigate CP volume alterations in depression and their associations with inflammation.

METHODS

51 depressed participants (HDRS score > 13) and 25 age- and sex-matched healthy controls (HCs) from the Wellcome Trust NIMA consortium were re-analysed for the study. All the participants underwent full peripheral cytokine profiling and simultaneous [11C]PK11195 PET/structural MRI imaging for measuring neuroinflammation and CP volume respectively.

RESULTS

We found a significantly greater CP volume in depressed subjects compared to HCs (t(76) = +2.17) that was positively correlated with [11C]PK11195 PET binding in the anterior cingulate cortex (r = 0.28, p = 0.02), prefrontal cortex (r = 0.24, p = 0.04), and insular cortex (r = 0.24, p = 0.04), but not with the peripheral inflammatory markers: CRP levels (r = 0.07, p = 0.53), IL-6 (r = -0.08, p = 0.61), and TNF-α (r = -0.06, p = 0.70). The CP volume correlated with the [11C]PK11195 PET binding in CP (r = 0.34, p = 0.005). Integration of transcriptomic data from the Allen Human Brain Atlas with the brain map depicting the correlations between CP volume and PET imaging found significant gene enrichment for several pathways involved in neuroinflammatory response.

CONCLUSION

This result supports the hypothesis that changes in brain barriers may cause reduction in solute exchanges between blood and CSF, disturbing the brain homeostasis and ultimately contributing to inflammation in depression. Given that CP anomalies have been recently detected in other brain disorders, these results may not be specific to depression and might extend to other conditions with a peripheral inflammatory component.

Psychoneuroimmunology: The new frontier in suicide research

Elucidating complex, multifactorial phenomena like suicide and suicidal behaviors (SSB) require multidisciplinary fields such as Psychoneuroimmunology (PNI). Indeed, our appreciation of the bidirectional communication channels between the brain and the rest of the body with its immune arsenal as the key player has positioned PNI as a promising field of research. We now know that major psychiatric, behavioral, and somatic disorders related to SSB accompany neuroimmune dysregulation. These disorders range from depression, emotional dysregulation, atopy, and epilepsy to certain viral and parasitic infections. By utilizing epidemiological, genetic, microbial, and molecular approaches, the PNI research community has excogitated novel biomarker candidates and pathways in support of SSB risk stratification at individual level. This remarkable progress in just two previous decades shall, if successful, help implement personalized prevention and treatment strategies, using PNI-assisted tools. The aims of this narrative review and opinion piece are to summarize important discoveries concerning the role of neuroimmune activation in SSB and to highlight important future directions for the field. Major caveats of the findings concerning methodological approaches, clinical reality of frequent comorbid psychopathology, and novel molecular targets are presented. Finally, this review calls on the PNI research community for increased attention towards factors that promote resilience to suicide, while accepting "consciousness" under its wing. Thus, PNI represents the new frontier in suicide research. Future breakthroughs in this discipline shall bring us closer to understanding the biological substrates of qualia i.e., subjective, and experiential meanings of life and death.

Electroconvulsive therapy increases temporarily plasma vascular endothelial growth factor in patients with major depressive disorder

OBJECTIVES

Vascular endothelial growth factor (VEGF) has been related to the etiology of major depressive disorder (MDD). The findings involving the effects of electroconvulsive therapy (ECT) on the VEGF levels have been conflicting. The aim was to examine the possible changes in the VEGF levels and their associations with clinical outcome in patients with MDD during ECT.

METHODS

The study comprised 30 patients suffering from MDD. Their plasma VEGF levels were measured at baseline and 2 and 4 hr after the first, fifth, and last ECT session. The severity of depression was quantified by the Montgomery-Asberg Depression Rating Scale (MADRS).

RESULTS

The VEGF levels increased between the 2-hr and 4-hr measurements during the first (p = .003) and the fifth (p = .017) sessions. The baseline VEGF levels between individual ECT sessions remained unchanged during the ECT series. No correlations were found between the increased VEGF levels and the clinical outcome.

CONCLUSIONS

Electroconvulsive therapy increased the VEGF levels repeatedly at the same time point in two different ECT sessions. These increases had no association with the response to ECT. Consequently, VEGF may act as a mediator in the mechanism of action of ECT.

Relationships between inflammatory markers and suicide risk status in major depression

Pro-inflammatory status has been implicated in depression and suicidal behaviors. Polyunsaturated fatty acids (PUFAs) and cytokines, two types of inflammatory biomarkers, have been associated with suicide, independent of depression severity. How these biomarkers relate to each other is less clear. We measured plasma phospholipid levels of arachidonic acid (AA%), docosahexaenoic acid (DHA%), and eicosapentaenoic acid (EPA%) as a percentage of total phospholipids, as well as serum interleukin-6 (IL-6), interleukin-1β (IL-1β) and tumor necrosis factor α (TNF-α), in 80 patients with major depressive disorder (MDD) and 24 healthy controls (HC). Individual PUFA and cytokine species were compared using ANOVA across four suicide risk-stratified groups: 1) highest-risk, recent (within 5 years) suicide attempters (n = 20); 2) high-risk, severe current suicidal ideators (having intent or plan) with no recent attempt history (n = 22); 3) low-risk, current non-ideators who were also lifetime non-attempters (n = 38); and 4) HC (n = 24). None of the participants were enrolled following an acute suicide attempt. Of biomarkers studied, only DHA% (p = 0.012) and IL-1β (p = 0.002) differed between groups. In post-hoc testing, DHA% was lower in attempters than ideators (p = 0.018) or MDD non-ideators (trend level, p = 0.073). IL-1β was lowest in attempters, differentiating them from ideators (p = 0.009) and HC (p = 0.004). Recent suicide attempt, one of the most powerful predictors of suicide risk, was also most closely tied to inflammatory indices in this study. Low DHA% as an indicator of suicide risk is consistent with previous reports; however, lower IL-1β was unexpected and may relate to acuity/chronicity of inflammation. There is a need for prospective studies of immune status with respect to suicidal behaviors.

Differential effects on blood and cerebrospinal fluid immune protein markers and kynurenine pathway metabolites from aerobic physical exercise in healthy subjects

Mounting evidence shows that physical exercise modulates systemic inflammation. However, its effect on cerebrospinal fluid (CSF) immune-marker profiles in man are largely unknown. We here report a study on healthy subjects (n = 27, males = 12, mean age 28.7, range 22-52) allocated to either an acute exercise setting over four consecutive days, or a training intervention over 4 weeks. Paired plasma and CSF samples collected at baseline, after 7 days of exercise abstention, and the day after completion of the exercise interventions, were analyzed for protein inflammation markers using a multiplex proximity extension assay and neurotransmitters and kynurenine pathway (KP) metabolites using liquid chromatography, respectively. Routine cell counts, and albumin, immunoglobulin G and neurofilament light chain concentrations in CSF remained unchanged in both paradigms, while several inflammatory proteins became upregulated after acute exercise. However, only changes in three CSF (vascular endothelial growth factor-A, interleukin-7 and matrix metalloproteinase-10) and 12 plasma proteins reached significance levels after adjustment for multiple comparisons and exclusion of less stable proteins. Similarly, KP metabolites only changed among participants after acute exercise, while neurotransmitter levels, except for increased CSF serine, remained stable. Both in plasma and CSF changes in KP metabolites and inflammatory proteins correlated, suggesting that these processes are functionally linked. These findings suggest that acute aerobic physical exercise affects immune markers and KP metabolites systemically and in the CSF.

The role of gene polymorphisms, and analysis of peripheral and central levels of interleukins in suicidal behavior: A systematic review

In terms of the physiological characteristics of suicidal behavior (SB) disorder, an increase inflammation response has been reported in these individuals. Therefore, the pro-inflammatory and anti-inflammatory activities of interleukins are adequate markers to research in order to understand the pathogenesis of SB. For that reason, the aim of this systematic review was to evaluate the role of interleukins in individuals with suicidal behavior disorder. A systematic search was performed in PubMed, Scopus and EBSCO databases up to July 2019. We used the words "interleukin" AND "suicide", "interleukin" AND "suicidal", and "IL-". Articles where interleukins concentrations were measured in individuals with SB and/or genetic studies addressing interleukins genes variants as possible markers to SB were included. A total of 54 articles were included. Articles that measured interleukin levels comprised 1111 cases and 1588 controls; whereas the genetic studies comprised 3082 cases and 5148 controls. These studies evaluated the concentrations of IL-1β, IL-2, IL-3, IL-4, IL-5, IL-6, IL-8, IL-10, sIL-2R in serum, plasma. The pro-inflammatory interleukins concentrations were higher in cases than in controls; however, we observed heterogeneity in the measurements and sample sources. Whereas, 9 polymorphisms of IL-1α, IL-1β, IL-6, IL-1β-8 genes were analyzed in association with suicide behavior disorder, though no conclusive outcomes were attained. Our results suggest that individuals with suicide risk undergo continuous stress that could trigger the release and circulation of pro-inflammatory interleukins and therefore their concentration in plasma. However, more studies are necessary in order to reach conclusively outcomes.

Examination and characterisation of the effect of amitriptyline therapy for chronic neuropathic pain on neuropeptide and proteomic constituents of human cerebrospinal fluid

INTRODUCTION

Amitriptyline is prescribed to reduce the intensity of chronic neuropathic pain. There is a paucity of validated in vivo evidence in humans regarding amitriptyline's mechanism of action. We examined the effect of amitriptyline therapy on cerebrospinal fluid (CSF) neuropeptides and proteome in patients with chronic neuropathic pain to identify potential mechanisms of action of amitriptyline.

METHODS

Patients with lumbar radicular neuropathic pain were selected for inclusion with clinical and radiological signs and a >50% reduction in pain in response to a selective nerve root block. Baseline (pre-treatment) and 8-week (post-treatment) pain scores with demographics were recorded. CSF samples were taken at baseline (pre-treatment) and 8 weeks after amitriptyline treatment (post-treatment). Proteome analysis was performed using mass spectrometry and secreted cytokines, chemokines and neurotrophins were measured by enzyme-linked immunosorbent assay (ELISA).

RESULTS

A total of 9/16 patients experienced a >30% reduction in pain after treatment with amitriptyline and GO analysis demonstrated that the greatest modulatory effect was on immune system processes. KEGG analysis also identified a reduction in PI3K-Akt and MAPK signalling pathways in responders but not in non-responders. There was also a significant decrease in the chemokine eotaxin-1 (p ​= ​0.02) and a significant increase in the neurotrophin VEGF-A (p ​= ​0.04) in responders.

CONCLUSION

The CSF secretome and proteome was modulated in responders to amitriptyline verifying many pre-clinical and in vitro models. The predominant features were immunomodulation with a reduction in pro-inflammatory pathways of neuronal-glia communications and evidence of a neurotrophic effect.

Serotonin Reuptake Inhibitors and the Gut Microbiome: Significance of the Gut Microbiome in Relation to Mechanism of Action, Treatment Response, Side Effects, and Tachyphylaxis

The monoamine hypothesis of psychopharmacology has been dominating the biological psychiatric research field for decades. Currently psychiatric research has increasingly appreciated psychiatric disorders and suicidal behavior as being highly complex and multi-etiological. In this pathway the gut microbiome and its interrelationship with the brain is gaining traction. The usage of selective serotonin reuptake inhibitors (SSRIs) is increasing in the general population. This is due to their effect on a broad range of psychiatric disorders, and their favorable side effect profile. Still, there are enigmatic aspects about SSRIs, such as the difficulty to predict effect in individual patients, inter-individual differences in side effect, tachyphylaxis (a sudden loss of response to a certain drug), and to date, uncertainties on how they exert their clinical effect. A majority of the serotonin in the human body is produced within the gut, and SSRIs affect enteric neurons. They also exhibit antimicrobial properties that comes with the potential of disrupting microbial hemostasis. We propose that the role of the gut-brain axis and the gut microbiome in relation to psychopharmacology should be more highlighted. With this article, together with similar articles, we would like to provide a hypothetical framework for future studies within this field. We believe that this would have the potential to provide a paradigm shift within the field of psychopharmacology, and result in findings that potentially could contribute to the development of a more personalized and tailored treatment.

Post-stroke depression: Chaos to exposition

Cerebral ischemia contributes to significant disabilities worldwide, impairing cognitive function and motor coordination in affected individuals. Stroke has severe neuropsychological outcomes, the major one being a stroke. Stroke survivors begin to show symptoms of depression within a few months of the incidence that overtime progresses to become a long-term ailment. As the pathophysiology for the progression of the disease is multifactorial and complex, it limits the understanding of the disease mechanism completely. Meta-analyses and randomized clinical trials have shown that intervening early with tricyclic antidepressants and selective serotonin receptor inhibitors can be effective. However, these pharmacotherapies possess several limitations that have given rise to newer approaches such as brain stimulation, psychotherapy and rehabilitation therapy, which in today's time are gaining attention for their beneficial results in post-stroke depression (PSD). The present review highlights numerous factors like lesion location, inflammatory mediators and genetic abnormalities that play a crucial role in the development of depression in stroke patients. Further, we have also discussed various mechanisms involved in post-stroke depression (PSD) and strategies for early detection and diagnosis using biomarkers that may revolutionize treatment for the affected population. Towards the end, along with the preclinical scenario, we have also discussed the various treatment approaches like pharmacotherapy, traditional medicines, psychotherapy, electrical stimulation and microRNAs being utilized for effectively managing PSD.

Prospective study on cytokine levels in medication-naïve adolescents with first-episode major depressive disorder

BACKGROUND

Evidence suggests that depression is correlated with immune-inflammatory responses, and efforts have been made to identify the relationships between depression and inflammatory markers. This study investigated the level of cytokines before and after treatment for major depressive disorder (MDD) in medication-naïve adolescents with first-episode MDD and compared them with the levels in healthy adolescents. The relationship between cytokine levels and the severity of depressive symptoms was also examined.

METHODS

Twenty-five adolescents with MDD and 25 healthy controls aged 13 to 18 years were included in the study. Blood samples were obtained, and depression severity was assessed twice in the MDD group before and after treatment and once in the healthy group.

RESULTS

When compared with healthy controls, adolescents with MDD had lower levels of interleukin 2 (IL-2), interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α) and IL-10 before treatment and higher levels of IL-2, IFN-γ, and IL-10 after treatment. In addition, the IFN-γ levels correlated with depressive severity scores in both the Children's Depression Inventory (CDI) and Hamilton Depression Rating Scale (HDRS). The IL-10 level correlated with depressive severity only on the HDRS.

LIMITATIONS

The sample size was small, and the 12-week follow-up time after treatment was relatively short.

CONCLUSION

IL-2, IFN-γ, TNF-α, and IL-10 levels in medication-naïve adolescents with first-episode MDD differed from those in healthy controls. The levels of IL-2, IFN-γ, and IL-10 were altered after antidepressant treatment. Further, the IFN-γ and IL-10 levels correlated with the severity of depressive symptoms.

A Specific Inflammatory Profile Underlying Suicide Risk? Systematic Review of the Main Literature Findings

Consistent evidence indicates the association between inflammatory markers and suicidal behavior. The burden related to immunological differences have been widely documented in both major affective disorders and suicidal behavior. Importantly, abnormally elevated pro-inflammatory cytokines levels have been reported to correlate with suicidal behavior but whether and to what extent specific inflammatory cytokines abnormalities may contribute to our understanding of the complex pathophysiology of suicide is unknown. The present manuscript aimed to systematically review the current literature about the role of pro-inflammatory cytokines in suicidal behavior. Most studies showed a link between abnormally higher interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-β1, vascular endothelial growth factor (VEGF), kynurenic acid (KYN), and lower IL-2, IL-4, and interferon (IFN)-γ levels in specific brain regions and suicidal behavior. Unfortunately, most studies are not able to exclude the exact contribution of major depressive disorder (MDD) as a mediator/moderator of the link between inflammatory cytokines abnormalities and suicidal behavior. The association between suicidal patients (both suicide attempters or those with suicidal ideation) and the altered immune system was documented by most studies, but this does not reflect the existence of a specific causal link. Additional studies are needed to clarify the immune pathways underlying suicidal behavior.

Suicide and suicide risk

Although recent years have seen large decreases in the overall global rate of suicide fatalities, this trend is not reflected everywhere. Suicide and suicidal behaviour continue to present key challenges for public policy and health services, with increasing suicide deaths in some countries such as the USA. The development of suicide risk is complex, involving contributions from biological (including genetics), psychological (such as certain personality traits), clinical (such as comorbid psychiatric illness), social and environmental factors. The involvement of multiple risk factors in conveying risk of suicide means that determining an individual's risk of suicide is challenging. Improving risk assessment, for example, by using computer testing and genetic screening, is an area of ongoing research. Prevention is key to reduce the number of suicide deaths and prevention efforts include universal, selective and indicated interventions, although these interventions are often delivered in combination. These interventions, combined with psychological (such as cognitive behavioural therapy, caring contacts and safety planning) and pharmacological treatments (for example, clozapine and ketamine) along with coordinated social and public health initiatives, should continue to improve the management of individuals who are suicidal and decrease suicide-associated morbidity.

Markers of central inflammation in major depressive disorder: A systematic review and meta-analysis of studies examining cerebrospinal fluid, positron emission tomography and post-mortem brain tissue

BACKGROUND

Increased peripheral inflammation has been consistently reported in patients with major depressive disorder (MDD). However, only few studies have explored markers of central (brain) inflammation in patients with MDD. The aim of this study is to systematically review in vivo and post-mortem markers of central inflammation, including studies examining cerebrospinal fluid (CSF), positron emission tomography, and post-mortem brain tissues in subjects suffering with MDD compared with controls.

METHODS

PubMed and Medline databases were searched up to December 2018. We included studies measuring cerebrospinal fluid (CSF) cytokines and chemokines, positron emission tomography (PET) studies; and post-mortem studies measuring cytokines, chemokines and cell-specific markers of microglia and astrocytes, all in MDD. A meta-analysis was performed only for CSF and PET studies, as studies on post-mortem markers of inflammation had different cell-specific markers and analysed different brain regions.

RESULTS

A total of 69 studies met the inclusion criteria. CSF levels of IL-6 and TNF-α were higher in patients with MDD compared with controls (standardised mean difference SMD 0.37, 95%CI: 0.17-0.57 and SMD 0.58, 95%CI 0.26-0.90, respectively). CSF levels of IL-6 were increased in suicide attempters regardless of their psychiatric diagnosis. Translocator protein, a PET marker of central inflammation, was elevated in the anterior cingulate cortex and temporal cortex of patients with MDD compared with controls (SMD 0.78, 95%CI: 0.41-1.16 and SMD 0.52, 95%CI: 0.19-0.85 respectively). Abnormalities in CSF and PET inflammatory markers were not correlated with those in peripheral blood. In post-mortem studies, two studies found increased markers of microglia in MDD brains, while four studies found no MDD related changes. Of the studies investigating expression of cell-specific marker for astrocytes, thirteen studies reported a decreased expression of astrocytes specific markers, two studies reported increased expression of astrocytes specific markers, and eleven studies did not detect any difference. Four out of six studies reported decreased markers of oligodendrocytes in the prefrontal cortex. Post-mortem brain levels of tumor necrosis alpha (TNF-α) were also found increased in MDD.

CONCLUSIONS

Our review suggests the presence of an increase in IL-6 and TNF-alpha levels in CSF and brain parenchyma, in the context of a possible increased microglia activity and reduction of astrocytes and oligodendrocytes markers in MDD. The reduced number of astrocytes may lead to compromised integrity of blood brain barrier with increased monocyte recruitment and infiltration, which is partly supported by post-mortem studies and by PET studies showing an increased TSPO expression in MDD.

Blood Vessels and Perivascular Phagocytes of Prefrontal White and Gray Matter in Suicide

Inflammatory processes may contribute to psychiatric disorders and suicide. Earlier, we reported greater densities of perivascular phagocytes in dorsal prefrontal white matter (DPFWM) in suicide than in non-suicide deaths. To distinguish between greater vascularity and greater coverage of vessels by perivascular phagocytes, and to determine whether the excess of perivascular phagocytes is derived from microglia or from non-parenchymal immune cells, we made stereological estimates of vascular surface area density (AVTOTAL) by staining for glucose transporter Glut-1, and the fraction of vascular surface area (AF) immunoreactive (IR) for CD163 (CD163 AF) in dorsal and ventral prefrontal white and gray matter. Manner of death or psychiatric diagnosis showed no association with CD163 AF in any region. Suicide was associated with a lower AVTOTAL compared with non-suicides in DPFWM (p = 0.018) but not with AVTOTAL in the 3 other regions of interest. Thus, the earlier observation of increased density of perivascular phagocytes in DPFWM after suicide cannot be attributed to infiltration by peripheral monocytes or to increased vascularity. Greater AVTOTAL ventrally than dorsally (p = 0.002) was unique to suicide and white matter.

Self-criticism, interpersonal conditions, and biosystemic inflammation in suicidal thoughts and behaviors within mood disorders: A bio-cognitive-interpersonal hypothesis

We review the theoretical and empirical literature on the role of self-concept in suicidal behavior in the context of mood disorders (i.e., unipolar depression and bipolar spectrum disorders). The main themes emanating from this review are then juxtaposed against (a) the Interpersonal-Psychological Theory of Suicide and (b) biological research on the role of inflammatory processes in suicidality. Such a juxtaposition paves the way for a bio-cognitive-interpersonal hypothesis. Pathologies of the self-concept-primarily self-criticism-propel mood disorder sufferers to generate interpersonal stress that culminates in two proximal causes of suicidality: thwarted belongingness and perceived burdensomeness. In turn, these two interpersonal conditions set in motion systemic biosystemic inflammation, serving as a proximal cause for suicidality in mood disorders. We conclude by describing a research project aimed at testing this hypothesis, and by outlining pertinent implications for assessment, treatment, and prevention.

Characterizing the course of suicidal ideation response to ketamine

BACKGROUND

No pharmacological treatments exist for active suicidal ideation (SI), but the glutamatergic modulator ketamine elicits rapid changes in SI. We developed data-driven subgroups of SI trajectories after ketamine administration, then evaluated clinical, demographic, and neurobiological factors that might predict SI response to ketamine.

METHODS

Data were pooled from five clinical ketamine trials. Treatment-resistant inpatients (n = 128) with DSM-IV-TR-diagnosed major depressive disorder (MDD) or bipolar depression received one subanesthetic (0.5 mg/kg) ketamine infusion over 40 min. Composite SI variable scores were analyzed using growth mixture modeling to generate SI response classes, and class membership predictors were evaluated using multinomial logistic regressions. Putative predictors included demographic variables and various peripheral plasma markers.

RESULTS

The best-fitting growth mixture model comprised three classes: Non-Responders (29%), Responders (44%), and Remitters (27%). For Responders and Remitters, maximal improvements were achieved by Day 1. Improvements in SI occurred independently of improvements in a composite Depressed Mood variable for Responders, and partially independently for Remitters. Indicators of chronic SI and self-injury were associated with belonging to the Non-Responder group. Higher levels of baseline plasma interleukin-5 (IL-5) were linked to Remitters rather than Responders.

LIMITATIONS

Subjects were not selected for active suicidal thoughts; findings only extend to Day 3; and plasma, rather than CSF, markers were used.

CONCLUSION

The results underscore the heterogeneity of SI response to ketamine and its potential independence from changes in Depressed Mood. Individuals reporting symptoms suggesting a longstanding history of chronic SI were less likely to respond or remit post-ketamine.

Baseline serum vascular endothelial growth factor levels predict treatment response to antipsychotic medication in patients with schizophrenia

Vascular endothelial growth factor (VEGF) is implicated in angiogenesis, blood flow, and neuroplasticity, which have previously been shown to contribute to schizophrenia and the mechanisms of action of antipsychotic medication. The aim of the present study was to investigate whether baseline serum VEGF levels predict treatment responses to antipsychotic medication. Drug-free adults with schizophrenia were administered monotherapy with atypical antipsychotic drugs for 6 weeks. Participants' psychiatric symptoms were assessed using the positive and negative symptom scale (PANSS) before and after treatment. Blood samples for VEGF measurements were collected from 201 participants comprising 83 healthy controls and 118 patients (i.e. only on admission). Baseline VEGF levels in adults with schizophrenia were significantly lower than those in the control group (t = 3.656, df = 199, P < 0.001). In particular, pretreatment VEGF levels were significantly higher in patients responding to drug treatment at follow-up (≥ 50% reduction in initial PANSS total) (t = 4.743, df = 116, P < 0.001). The predictive power of serum VEGF levels was investigated using receiver operating characteristic curves. The area under the curve was 0.774 (95% confidence interval 0.688-0.846); for fixed specificity of 78.8%, the corresponding sensitivity was 63.5%. Results from this preliminary experiment suggest high baseline serum concentrations of VEGF may predict a better response to antipsychotic medications in adults with schizophrenia. Further studies using larger sample sizes are needed to verify the findings.

Vascular endothelial growth factor: Potential predictor of treatment response in major depression

OBJECTIVES

The aim of the study was to evaluate baseline plasma VEGF levels as a potential predictor of response to antidepressant pharmacotherapy. The study also sought to determine whether baseline plasma VEGF would be useful in predicting treatment outcome when two pharmacodynamically diverse agents with established antidepressant efficacy, escitalopram and quetiapine, were administered monotherapeutically to MDD patients.

METHODS

Two groups of qualifying MDD subjects were enrolled. One group was treated with escitalopram and the other with quetiapine. Plasma concentrations of VEGF were measured using Randox Technologies at baseline, and at weeks 8 and 12 of treatment.

RESULTS

We stratified the MDD patients into those who remitted and those who failed to respond. Mean baseline VEGF for the remitters and non-responders was 9.61  and 5.40 pg/ml, respectively (P < 0.0005). Using optimal data analysis a cut score of 7.49 pg/ml for baseline plasma VEGF distinguished remitters from non-responders with a 63% overall accuracy. The remission rate was comparable for both drugs (73 and 81% for quetiapine and escitalopram, respectively). VEGF levels did not significantly change following antidepressant treatment with either escitalopram or quetiapine when measured at 8 and 12 weeks; this result held true for both remitters and non-responders.

CONCLUSIONS

Our results suggest that VEGF may predict response to antidepressant treatment and may ultimately prove to be a potential biomarker that can be measured with a routine blood draw at the point of service.

Neuropathology of suicide: recent findings and future directions

Suicide is a major public health concern and a leading cause of death in most societies. Suicidal behaviour is complex and heterogeneous, likely resulting from several causes. It associates with multiple factors, including psychopathology, personality traits, early-life adversity and stressful life events, among others. Over the past decades, studies in fields ranging from neuroanatomy, genetics and molecular psychiatry have led to a model whereby behavioural dysregulation, including suicidal behaviour (SB), develops as a function of biological adaptations in key brain systems. More recently, the unravelling of the unique epigenetic processes that occur in the brain has opened promising avenues in suicide research. The present review explores the various facets of the current knowledge on suicidality and discusses how the rapidly evolving field of neurobehavioural epigenetics may fuel our ability to understand, and potentially prevent, SB.

Biomarkers for depression: recent insights, current challenges and future prospects

A plethora of research has implicated hundreds of putative biomarkers for depression, but has not yet fully elucidated their roles in depressive illness or established what is abnormal in which patients and how biologic information can be used to enhance diagnosis, treatment and prognosis. This lack of progress is partially due to the nature and heterogeneity of depression, in conjunction with methodological heterogeneity within the research literature and the large array of biomarkers with potential, the expression of which often varies according to many factors. We review the available literature, which indicates that markers involved in inflammatory, neurotrophic and metabolic processes, as well as neurotransmitter and neuroendocrine system components, represent highly promising candidates. These may be measured through genetic and epigenetic, transcriptomic and proteomic, metabolomic and neuroimaging assessments. The use of novel approaches and systematic research programs is now required to determine whether, and which, biomarkers can be used to predict response to treatment, stratify patients to specific treatments and develop targets for new interventions. We conclude that there is much promise for reducing the burden of depression through further developing and expanding these research avenues.

Alterations in VEGF expression induced by antidepressant drugs in female rats under chronic social stress

Vascular endothelial growth factor (VEGF) is thought to serve a role in neurogenesis and the stress response. Although a definite link between the action of antidepressants and VEGF has not been identified, it is assumed that VEGF, as a neurotrophic factor, serves an important role in the effects of antidepressant treatment. To examine this, the present study subjected adult female rats to four weeks of social instability stress and measured the effect of antidepressant treatment on the expression of VEGF. Firstly, endocrine markers of stress and body weight were measured in parallel with behavioral tests prior to and following subjection to stress. Then, the effect of 28-day daily treatment with desipramine (DMI; 10 mg/kg), fluoxetine (5 mg/kg) or tianeptine (10 mg/kg) on the number of copies of VEGF mRNA in the amygdala, hippocampus and hypothalamus, and on serum VEGF protein levels, of rats subjected to chronic stress was determined. In addition, the weight of the adrenal glands was measured following subjection to stress. Exposure to chronic stress was found to increase the rats' sucrose preference, and diminish their tendency for general exploration and time spent in the open. The relative adrenal weights of the stressed rats were significantly increased compared with the control. Plasma concentrations of corticosterone and adrenocorticotropic hormone were not significantly augmented. In addition, the present study identified that stress elevated VEGF mRNA expression in all studied neural structures. Furthermore, the results identified that the stress-induced increase in VEGF mRNA expression in the amygdala and hypothalamus was attenuated by long-term administration of DMI. Conversely, a decrease in serum VEGF concentration was observed in stressed rats, which was not reversed by treatment with antidepressants. In conclusion, the current study suggests that under conditions of stress, VEGF serves a role in the mechanism of action of DMI, through modulating activity of the norepinephrine system.

VEGF-related polymorphisms identified by GWAS and risk for major depression

Depression is a common, severe, disabling mental disease that affects millions of people of all ages worldwide. Various studies have shown that neurotrophic/growth factors have a key role in depression and, more specifically, vascular endothelial growth factor (VEGF) is implicated in the pathogenesis of depression. The purpose of this study was to investigate the potential links between four VEGF-related single-nucleotide polymorphisms (SNPs), previously identified through a genome-wide association study (GWAS) and depression. The direct effects and epistatic interactions of the four VEGF-related SNPs (rs10738760, rs6921438, rs6993770 and rs4416670) on depression were investigated through a case-control study including 437 individuals diagnosed with depression and 477 healthy volunteers as controls. Gender, age and body mass index influence was additionally analyzed. The SNP rs4416670 was associated with increased risk for depression (OR: 1.60, P: 0.010). This result demonstrates the existence of relationships between VEGF genetic determinants and depression. This novel association reveals new molecular mechanisms suggesting the potential role of VEGF in depression development that could help to promote a personalized prediction for this severe common disease.

Prepubertal Ovariectomy Exaggerates Adult Affective Behaviors and Alters the Hippocampal Transcriptome in a Genetic Rat Model of Depression

Major depressive disorder (MDD) is a debilitating illness that affects twice as many women than men postpuberty. This female bias is thought to be caused by greater heritability of MDD in women and increased vulnerability induced by female sex hormones. We tested this hypothesis by removing the ovaries from prepubertal Wistar Kyoto (WKY) more immobile (WMI) females, a genetic animal model of depression, and its genetically close control, the WKY less immobile (WLI). In adulthood, prepubertally ovariectomized (PrePubOVX) animals and their Sham-operated controls were tested for depression- and anxiety-like behaviors, using the routinely employed forced swim and open field tests, respectively, and RNA-sequencing was performed on their hippocampal RNA. Our results confirmed that the behavioral and hippocampal expression changes that occur after prepubertal ovariectomy are the consequences of an interaction between genetic predisposition to depressive behavior and ovarian hormone-regulated processes. Lack of ovarian hormones during and after puberty in the WLIs led to increased depression-like behavior. In WMIs, both depression- and anxiety-like behaviors worsened by prepubertal ovariectomy. The unbiased exploration of the hippocampal transcriptome identified sets of differentially expressed genes (DEGs) between the strains and treatment groups. The relatively small number of hippocampal DEGs resulting from the genetic differences between the strains confirmed the genetic relatedness of these strains. Nevertheless, the differences in DEGs between the strains in response to prepubertal ovariectomy identified different molecular processes, including the importance of glucocorticoid receptor-mediated mechanisms, that may be causative of the increased depression-like behavior in the presence or absence of genetic predisposition. This study contributes to the understanding of hormonal maturation-induced changes in affective behaviors and the hippocampal transcriptome as it relates to genetic predisposition to depression.

Voluntary running improves depressive behaviours and the structure of the hippocampus in rats: A possible impact of myokines

This study investigated the impact of voluntary exercise on depressive behaviours, serum and hippocampal levels of myokines, and histopathological features of hippocampal formation in rats. Depressed rats were allowed to voluntarily run on a wheel for 3weeks. Locomotor activity was assessed by a forced swimming test and the myokine levels in sera and hippocampal homogenates were measured using Enzyme-linked Immunosorbent Assay. Brain sections were analysed for hippocampal structure and neuronal counts. Voluntary running produced significant increase in the distance moved by rats and significant decrease in immobility duration. After voluntary running, there were significant increases in serum and hippocampal brain-derived neurotrophic factor (BDNF) and macrophage migration inhibitory factor (MIF), significant increase in hippocampal vascular endothelial growth factor (VEGF), and significant decrease in serum interleukin-6 (IL-6). Significant correlation was detected between the serum levels of BDNF and MIF (r=0.276) as well as IL-6 (r=-0.340). In addition, significant correlation was observed between hippocampal BDNF levels and MIF (r=0.500) and VEGF levels (r=0.279). After voluntary running, there was significant decrease in number degenerated neurons in hippocampal areas and significant increase in number of healthy neurons in the upper limb of the dentate gyrus, but not in its lower limb, compared to depression group. This study showed the relation of myokines to the development and/or relief of depression, as well as the correlation between serum and hippocampal myokine levels. Attention should be paid to studying the biological effects of myokines on different hippocampal areas that could respond differently to treatments.

Inflammatory markers and suicidal attempts in depressed patients: A review

Major depressive disorder is a chronic and invalidating psychiatric illness and is associated with a greater risk of suicidal behaviors. In recent decades many data have supported a biological link between depressive states and inflammation. Pro-inflammatory cytokines have been found to rise, first of all TNF-α and IL-6. Suicidal behaviors have been consistently associated with increased levels of IL-6 and decreased levels of IL-2. The aim of this review is to investigate the relationship between inflammatory markers in depressed patients with or without suicidal attempts compared to healthy controls.

Neuroinflammation in suicide: Toward a comprehensive model

OBJECTIVES

Suicidal behaviour (SB) entered the DSM-5, underlying a specific biological vulnerability. Then, recent findings suggested a possible role of the immune system in SB pathogenesis. The objective of this review is to present these main immune factors involved in SB pathogenesis.

METHODS

We conducted a review using Preferred Reporting Items for Systematic reviews and Meta-Analysis criteria, and combined ("Inflammation") AND ("Suicidal ideation" OR "Suicidal attempt" OR "suicide").

RESULTS

Post mortem studies demonstrated associations between suicide and inflammatory cytokines in the orbitofrontal cortex, a brain region involved in suicidal vulnerability. Also, microgliosis and monocyte-macrophage system activation may be a useful marker of suicide neurobiology. Kynurenine may influence inflammatory processes, and related molecular pathways may be involved in SB pathophysiology. Few recent studies associated inflammatory markers with suicidal vulnerability: serotonin dysfunction, impulsivity and childhood trauma. Interestingly, the perception of threat that leads suicidal individuals to contemplate suicide may activate biological stress responses, including inflammatory responses.

CONCLUSIONS

Translational projects would be crucial to identify a specific marker in SB disorders, to investigate its clinical correlations, and the interaction between inflammatory cytokines and monoamine systems in SB. These researches might lead to new biomarkers and novel directions for therapeutic strategies.

Biological risk factors for suicidal behaviors: a meta-analysis

Prior studies have proposed a wide range of potential biological risk factors for future suicidal behaviors. Although strong evidence exists for biological correlates of suicidal behaviors, it remains unclear if these correlates are also risk factors for suicidal behaviors. We performed a meta-analysis to integrate the existing literature on biological risk factors for suicidal behaviors and to determine their statistical significance. We conducted a systematic search of PubMed, PsycInfo and Google Scholar for studies that used a biological factor to predict either suicide attempt or death by suicide. Inclusion criteria included studies with at least one longitudinal analysis using a biological factor to predict either of these outcomes in any population through 2015. From an initial screen of 2541 studies we identified 94 cases. Random effects models were used for both meta-analyses and meta-regression. The combined effect of biological factors produced statistically significant but relatively weak prediction of suicide attempts (weighted mean odds ratio (wOR)=1.41; CI: 1.09-1.81) and suicide death (wOR=1.28; CI: 1.13-1.45). After accounting for publication bias, prediction was nonsignificant for both suicide attempts and suicide death. Only two factors remained significant after accounting for publication bias-cytokines (wOR=2.87; CI: 1.40-5.93) and low levels of fish oil nutrients (wOR=1.09; CI: 1.01-1.19). Our meta-analysis revealed that currently known biological factors are weak predictors of future suicidal behaviors. This conclusion should be interpreted within the context of the limitations of the existing literature, including long follow-up intervals and a lack of tests of interactions with other risk factors. Future studies addressing these limitations may more effectively test for potential biological risk factors.

Role of trophic factors GDNF, IGF-1 and VEGF in major depressive disorder: A comprehensive review of human studies

RATIONALE

The neurotrophin hypothesis of major depressive disorder (MDD) postulates that this illness results from aberrant neurogenesis in brain regions that regulates emotion and memory. Notwithstanding this theory has primarily implicated BDNF in the neurobiology of MDD. Recent evidence suggests that other trophic factors namely GDNF, VEGF and IGF-1 may also be involved.

PURPOSE

The present review aimed to critically summarize evidence regarding changes in GDNF, IGF-1 and VEGF in individuals with MDD compared to healthy controls. In addition, we also evaluated the role of these mediators as potential treatment response biomarkers for MDD.

METHODS

A comprehensive review of original studies studies measuring peripheral, central or mRNA levels of GDNF, IGF-1 or VEGF in patients with MDD was conducted. The PubMed/MEDLINE database was searched for peer-reviewed studies published in English through June 2nd, 2015.

RESULTS

Most studies reported a reduction in peripheral GDNF and its mRNA levels in MDD patients versus controls. In contrast, IGF-1 levels in MDD patients compared to controls were discrepant across studies. Finally, most studies reported high peripheral VEGF levels and mRNA expression in MDD patients compared to healthy controls.

CONCLUSIONS

GDNF, IGF-1 and VEGF levels and their mRNA expression appear to be differentially altered in MDD patients compared to healthy individuals, indicating that these molecules might play an important role in the pathophysiology of depression and antidepressant action of therapeutic interventions.

Possible Biomarkers of Chronic Stress Induced Exhaustion - A Longitudinal Study

Background

Vascular endothelial growth factor (VEGF), epidermal growth factor (EGF) and monocyte chemotactic protein-1 (MCP-1) have previously been suggested to be potential biomarkers for chronic stress induced exhaustion. The knowledge about VEGF has increased during the last decades and supports the contention that VEGF plays an important role in stress and depression. There is scarce knowledge on the possible relationship of EGF and MCP-1 in chronic stress and depression. This study further examines the role of VEGF, EGF and MCP-1 in women with chronic stress induced exhaustion and healthy women during a follow-up period of two years.

Methods and Findings

Blood samples were collected from 105 women with chronic stress induced exhaustion on at least 50% sick leave for at least three months, at inclusion (T0), after 12 months (T12) and after 24 months (T24). Blood samples were collected at inclusion (T0) in 116 physically and psychiatrically healthy women. The plasma levels of VEGF, EGF and MCP-1 were analyzed using Biochip Array Technology. Women with chronic stress induced exhaustion had significantly higher plasma levels of VEGF and EGF compared to healthy women at baseline, T12 and at T24. There was no significant difference in plasma levels of MCP-1. Plasma levels of VEGF and EGF decreased significantly in women with chronic stress induced exhaustion during the two years follow-up.

Conclusions

The replicated findings of elevated levels of VEGF and EGF in women with chronic stress induced exhaustion and decreasing plasma levels of VEGF and EGF during the two years follow-up add important knowledge to the pathophysiology of chronic stress induced exhaustion.

Lipid peroxidation biomarkers in adolescents with or at high-risk for bipolar disorder

BACKGROUND

Prior work suggests that adult bipolar disorder (BD) is associated with increased oxidative stress and inflammation. This exploratory study examined markers of lipid and protein oxidation and inflammation in adolescents with and at varying risk for BD type I (BD-I).

METHODS

Blood was obtained from four groups of adolescents (9-20 years of age): (1) healthy comparison subjects with no personal or family history of psychiatric disorders (n=13), (2) subjects with no psychiatric diagnosis and at least one parent with BD-I ('high-risk', n=15), (3) subjects with at least one parent with BD-I and a diagnosis of depressive disorder not-otherwise-specified ('ultra-high-risk', n=20), and (4) first-episode patients exhibiting mixed or manic symptoms that received a diagnosis of BD-I (n=16). Plasma levels of lipid peroxidation (LPH, 4-HNE, 8-ISO), protein carbonyl, and inflammation (IL-1α-β, IL-6, IL-10, IFNγ, TNFα) were assessed using analysis of variance and covariance models.

RESULTS

LPH was lower in adolescents with fully syndromal BD than controls, while LPH levels in the at-risk groups were between healthy controls and fully syndromal BD. Post-hoc analysis showed a non-significant increase in the (4-HNE+8-ISO)/LPH ratio suggesting a potential conversion of LPH into late-stage markers of lipid peroxidation. There were no significant differences among protein carbonyl content and inflammatory markers.

CONCLUSIONS

In adolescents, fully syndromal BD is associated with significant reductions in LPH levels, and LPH levels decrease along the spectrum of risk for BD-I. Quantifying lipid peroxidation in longitudinal studies may help clarify the role of LPH in BD risk progression.

A Potential Contribution of Chemokine Network Dysfunction to the Depressive Disorders

In spite of many years of research, the pathomechanism of depression has not yet been elucidated. Among many hypotheses, the immune theory has generated a substantial interest. Up till now, it has been thought that depression is accompanied by the activation of inflammatory response and increase in pro-inflammatory cytokine levels. However, recently this view has become controversial, mainly due to the family of small proteins called chemokines. They play a key role in the modulation of peripheral function of the immune system by controlling immune reactions, mediating immune cell communication, and regulating chemotaxis and cell adhesion. Last studies underline significance of chemokines in the central nervous system, not only in the neuromodulation but also in the regulation of neurodevelopmental processes, neuroendocrine functions and in mediating the action of classical neurotransmitters. Moreover, it was demonstrated that these proteins are responsible for maintaining interactions between neuronal and glial cells both in the developing and adult brain also in the course of diseases. This review outlines the role of chemokine in the central nervous system under physiological and pathological conditions and their involvement in processes underlying depressive disorder. It summarizes the most important data from experimental and clinical studies.

The role of cytokines in the pathophysiology of suicidal behavior

OBJECTIVE

Immune dysregulation has been implicated in depression and other psychiatric disorders. What is less clear is how immune dysregulation can affect risk of suicidal behavior. We reviewed the scientific literature concerning cytokines related to suicidal ideation, suicidal behavior and suicide, and surveyed clinical and neurobiological factors associated with cytokine levels that may modulate effects of inflammation on suicide risk.

METHODS

We searched PubMed, Embase, Scopus and PsycINFO for relevant studies published from 1980 through February, 2015. Papers were included if they were written in English and focused on cytokine measurements in patients with suicidal behaviors.

RESULTS

The literature search yielded 22 studies concerning cytokines and suicidal ideation, suicide attempts or suicide completion. The most consistent finding was elevated interleukin (IL)-6, found in 8 out of 14 studies, in CSF, blood, and postmortem brain. In one study, IL-6 in CSF was also found to be higher in violent than nonviolent attempters and to correlate with future suicide completion. Low plasma IL-2 was observed in 2 studies of suicide attempters, while divergent results were seen for tumor necrosis factor (TNF)-α, interferon (IFN)-γ, transforming growth factor (TGF)-β, IL-4, and soluble Il-2 receptors.

CONCLUSIONS

Given the complexity suggested by the heterogenous cytokine findings, putative mediators and moderators of inflammation on suicidal behavior merit further study. Elevated IL-6 was the most robust cytokine finding, associated with suicidal ideation and both nonfatal suicide attempts and suicides. Future studies should evaluate the predictive value of high IL-6, consider how this may alter brain function to impact suicidal behavior, and explore the potential beneficial effects of reducing IL-6 on suicide risk.

[Biological basis of suicidal behavior]

Based on current clinical and classification concepts of suicidality, the biological parameters characteristic of suicidal behavior, completed and uncompleted suicides reported in the last few decades are discussed. The results obtained in the studies of neurotransmitter and other brain systems, immune system, lipid and other types of metabolism as well as data of neuroimaging brain studies and post-mortem investigation of brain structures are presented.

Insufficient glucocorticoid signaling and elevated inflammation in coronary heart disease patients with comorbid depression

Coronary heart disease (CHD) and depression are very common and often co-existing disorders. In addition to psychological and social morbidity, depression exacerbates adverse cardiac outcomes in CHD patients. Inflammation has been proposed as one of the mechanisms involved in the association between these two debilitating diseases. Therefore, the present study aimed to evaluate inflammatory responses as well as to investigate the pathophysiological mechanisms underlying the putative inflammatory activation in CHD patients with and without depression, by assessing the function of two important biological factors regulating inflammation, the hypothalamus-pituitary-adrenal (HPA) axis and the glucocorticoid receptor (GR). Eighty-three CHD patients with (n=28) and without (n=55) comorbid depression were recruited from primary care services in South London. Depression status was assessed by means of Clinical Interview Schedule Revised for diagnosis of depression, and Beck Depression Inventory for the presence of depressive symptoms. Serum C-reactive protein (CRP), plasma vascular endothelial growth factor (VEGF), and plasma and salivary cortisol were measured using commercially available ELISA kits. Gene expression of GR and interleukin-6 (IL-6) were conducted via qPCR. GR sensitivity was evaluated in vitro in isolated peripheral blood mononuclear cells using the dexamethasone inhibition of lipopolysaccharide-stimulated IL-6 levels. Serum levels of kynurenine pathway metabolites were measured using high performance liquid chromatography. Our results show that CHD patients with depression had higher levels of CRP, IL-6 gene expression, and VEGF compared with CHD non-depressed, as well as lower plasma and saliva cortisol levels. The CHD depressed group also exhibited a reduction in GR expression and sensitivity. Finally, tryptophan levels were significantly lower in patients with depression, who also showed an increased kynurenine/tryptophan ratio. In conclusion, CHD patients with depression had elevated levels of inflammation in the context of HPA axis hypoactivity, GR resistance, and increased activation of the kynurenine pathway. Reduced cortisol bioavailability and attenuated glucocorticoid responsiveness due to decreased expression and sensitivity of GR may lead to insufficient glucocorticoid signaling and thus elevation of inflammation in these patients.