Venlafaxine inhibits the upregulation of plasma tumor necrosis factor-alpha (TNF-α) in the Chinese patients with major depressive disorder: a prospective longitudinal study

Sertraline with desvenlafaxine and sertraline with mirtazapine as treatment initiation in MDD patients with moderate to severe depression and effect on inflammatory markers

BACKGROUND

This study evaluated the effect of sertraline with desvenlafaxine and sertraline with mirtazapine on HAM-D score and inflammatory markers (IL-6 and TNF-α levels) in major depressive disorder.

METHODS

Patients (18-60 years) with MDD diagnosed by DSM-V criteria and HAM-D score 18 or more were included (n = 60). Group A patients (n = 30) received sertraline 50 mg/day and desvenlafaxine 50 mg/day. Group B patients (n = 30) received sertraline 50 mg/day and mirtazapine 30 mg/day. All patients were followed up for 8 weeks for the evaluation of clinical efficacy, safety, serum IL-6, and TNF-α levels.

RESULTS

Our study showed a comparatively similar and statistically significant (p < 0.05) reduction in HAM-D score in both groups in the 4th and 8th week of the treatment. Both drug combinations significantly (p < 0.05) decreased serum IL-6 and TNF-α after 8 weeks of treatment.

CONCLUSION

The present study suggests that the combination therapy (as treatment initiation) with sertraline and desvenlafaxine, and sertraline with mirtazapine is effective and well tolerated in MDD patients with moderate to severe depression, and their therapeutic efficacy is accompanied by decreased inflammatory markers (serum IL-6 and TNF-α).

Major depressive disorder with suicidal ideation or behavior in Chinese population: A scoping review of current evidence on disease assessment, burden, treatment and risk factors

BACKGROUND

Identifying and managing major depressive disorder (MDD) patients with suicidal ideation or behavior (MDSI) is critical for reducing the disease burden. This scoping review aims to map the existing evidence related to MDSI in the Chinese population.

METHOD

A scoping review was conducted to summarize the published evidence regarding epidemiology or disease burden, evaluation, diagnosis, management, and prognosis of MDSI. The search strategy imposed restriction on English or Chinese publications between 1 January 2011 and 28 February 2022.

RESULTS

Of the 14,005 identified records, 133 met the eligibility criteria and were included for analysis. The included studies were characterized as high heterogeneity in evaluation of suicidal ideation or behavior. Compared with MDD patients without suicidal ideation or behavior, MDSI patients were more likely to suffer from psychological and somatic symptoms, social function impairment, and lower quality of life. Younger age, female gender, longer disease course, and comorbid psychological or physical symptoms were consistently found to be risk factors of suicidal ideation or behavior. Relevant research gaps remain regarding comprehensive evaluation of standard clinical diagnosis, disease burden, social-cultural risk factors, and effectiveness of interventions targeting MDSI. Studies with large sample size, representative population are warranted to provide high-quality evidence.

CONCLUSIONS

MDD patients with suicidal ideation or behavior should be prioritized in treatment and resource allocation. Heterogeneity exists in the definition and evaluation of MDSI in different studies. To better inform clinical practice, it is imperative to establish a unified standard for evaluation and diagnosis of suicidal ideation or behavior among MDD population.

Update in the understanding of new daily persistent headache

Background Accumulating evidence suggests various specific triggers may lead to new daily persistent headache (NDPH)-like presentations, suggesting that new daily persistent headache is a heterogenous syndrome, and challenging the concept that new daily persistent headache is a primary headache disorder.Method We searched the PubMed database up to August 2022 for keywords including persistent daily headache with both primary and secondary etiologies. We summarized the literature and provided a narrative review of the clinical presentation, diagnostic work-ups, possible pathophysiology, treatment response, and clinical outcomes.Results and conclusion New daily persistent headache is a controversial but clinically important topic. New daily persistent headache is likely not a single entity but a syndrome with different etiologies. The issue with past studies of new daily persistent headache is that patients with different etiologies/subtypes were pooled together. Different studies may investigate distinct subsets of patients, which renders the inter-study comparison, both positive and negative results, difficult. The identification (and removal) of a specific trigger might provide the opportunity for clinical improvement in certain patients, even when the disease has lasted for months or years. Nonetheless, if there is a specific trigger, it remains unknown or unidentified for a great proportion of the patients. We need to continue to study this unique headache population to better understand underlying pathogenesis and, most importantly, to establish effective treatment strategies that hopefully resolve the continuous cycle of pain.

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.

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.

The molecular pathophysiology of depression and the new therapeutics

Major depressive disorder (MDD) is a highly prevalent and disabling disorder. Despite the many hypotheses proposed to understand the molecular pathophysiology of depression, it is still unclear. Current treatments for depression are inadequate for many individuals, because of limited effectiveness, delayed efficacy (usually two weeks), and side effects. Consequently, novel drugs with increased speed of action and effectiveness are required. Ketamine has shown to have rapid, reliable, and long-lasting antidepressant effects in treatment-resistant MDD patients and represent a breakthrough therapy for patients with MDD; however, concerns regarding its efficacy, potential misuse, and side effects remain. In this review, we aimed to summarize molecular mechanisms and pharmacological treatments for depression. We focused on the fast antidepressant treatment and clarified the safety, tolerability, and efficacy of ketamine and its metabolites for the MDD treatment, along with a review of the potential pharmacological mechanisms, research challenges, and future clinical prospects.

Pumpkin seed oil and zinc attenuate chronic mild stress perturbations in the cerebral cortex of rats

Purpose

This study aims to investigate the potential of pumpkin seed oil (PSO) and zinc to attenuate oxidative stress and neuroinflammation caused by chronic mild stress (CMS) in the cerebral cortex of male rats.

Design/methodology/approach

The rats were submitted to stress for six weeks and then the behavior of the rats was tested by forced swimming test (FST) and novel cage test. The treated groups were given venlafaxine (20 mg/kg), pumpkin seed oil (40 mg/kg) and zinc (4 mg/kg). The cortex homogenate was used for the detection of the oxidative stress parameters, the concentration of neurotransmitters, tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β), Na+/K+-ATPase activity, and the expression of histamine N-methyltransferase (Hnmt) and tyrosine hydroxylase (Th).

Findings

CMS causes a significant increase in immobility time in the FST and a significant decrease in the number of rearing in the novel cage test. CMS group showed a significant increase in alanine aminotransferase (ALT) activity, levels of cortisol, TNF-α, IL-1β, nitric oxide and malondialdehyde. CMS caused a significant decrease in the concentrations of serotonin, GABA, norepinephrine, and the activities of glutathione peroxidase, catalase, superoxide dismutase and Na+/K+-ATPase. CMS caused a marked reduction in the expression of Hnmt and Th in the cortex. PSO and zinc attenuated the Na+/K+-ATPase activity, oxidative parameters and neuroinflammation induced by the CMS, and this was reflected by the elevation of the concentration of neurotransmitters and reduction of cortisol and ALT, in addition to the behavior normalization. PSO and zinc attenuated the CMS by improving the antioxidant milieu and anti-inflammatory status of the cerebral cortex.

Originality/value

There are no studies on the effect of pumpkin seed oil on depression

Exploring the role of biologics in depression

Depression is a chronic and prevalent neuropsychiatric disorder; clinical symptoms include excessive sad mood, anhedonia, increased anxiety, disturbed sleep, and cognitive deficits. The exact etiopathogenesis of depression is not well understood. Studies have suggested that tumor necrosis factor-alpha (TNF-α) and interleukins (ILs) perform vital roles in the pathogenesis and treatment of depression. Increasing evidence suggests the upregulation of TNF-α and ILs expression in patients with depression. Therefore, biologics like TNF inhibitors (etanercept, infliximab, adalimumab) and IL inhibitors (ustekinumab) have become key compounds in the treatment of depression. Interestingly, treatment with an antidepressant has been found to decrease the TNF-α level and improve depression-like behaviors in several preclinical and clinical studies. In the current article, we have reviewed the recent findings linking TNF-α and the pathogenesis of depression proving TNF-α inhibitors as potential new therapeutic agents. Animal models and clinical studies further support that TNF-α inhibitors are effective in ameliorating depression-like behaviors. Moreover, studies showed that peripheral injection of TNF-α exhibits depressive symptoms. These symptoms have been improved by treatment with TNF-α inhibitors. Hence suggesting TNF-α inhibitors as potential new antidepressants for the management of depressive disorder.

Correlation Between Serum High-Sensitivity C-Reactive Protein, Tumor Necrosis Factor-Alpha, Serum Interleukin-6 and White Matter Integrity Before and After the Treatment of Drug-Naïve Patients With Major Depressive Disorder

Background

Previous studies have noticed that systemic inflammation may alter the integrity of white matter. However, how the levels of serum cytokine affect the integrity of white matter in major depressive disorder (MDD) patients are unclear. Our study aimed to investigate the association between the inflammatory cytokine levels and white matter microstructure in drug-naïve patients with MDD pre- and post-treatment.

Method

In total, 29 MDD patients and 25 healthy controls (HC) were included in this study. Diffusion tensor imaging (DTI) was conducted in all subjects at baseline, and the MDD patients were reassessed after venlafaxine treatment, using a tract-based spatial statistics (TBSS) analysis. Morning serum interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and high-sensitivity C-reactive protein (hs-CRP) concentrations in MDD patients were also measured pre- and post-treatment.

Results

Significantly reduced fractional anisotropy (FA) values were found in the bilateral superior fronto-occipital fasciculus (SFO), posterior limb of the internal capsule (IC-PL), and fornix compared with the HC, and FA values in these regions in MDD patients have risen to normal levels except the bilateral SFO after treatment. The FA value of the left IC-PL was inversely correlated with the peripheral hs-CRP levels in both pre- and post-treatment MDD patients.

Conclusion

Our results suggested that the white matter integrity in the left IC-PL was significantly inversely correlated with the peripheral hs-CRP levels in both pre- and post-treatment MDD patients.

Update of New Daily Persistent Headache

Purpose of Review

The diagnostic criteria of new daily persistent headache (NDPH) have been revised since 2013. The current review focused on the progress of NDPH research over the last few years.

Recent Findings

Various new triggers and different NDPH mimics have been reported. The association with both cephalic and extracephalic pathologies suggests that NDPH is rather a syndrome with more than one disease mechanism. Recent clinical studies confirmed that migrainous headache remained the most prominent phenotype of NDPH, echoing the change of the diagnostic criteria in 2013. Diagnostic workup, including imaging studies, was unremarkable, except serving to exclude secondary etiologies. Studies on treatment options have yet shown promising targets, and randomized clinical trials are still lacking.

Summary

Multiple mechanisms, both cranial and systemic, may be involved synergically in the generation of NDPH-like headaches. The search for effective treatment options should base on better understanding of disease mechanisms.

Changes in glial gene expression in the prefrontal cortex in relation to major depressive disorder, suicide and psychotic features

BACKGROUND

To establish whether major depressive disorder (MDD), suicidal behaviors and psychotic features contribute to glial alterations in the human prefrontal cortex.

MATERIALS AND METHODS

We compared mRNA expression using real-time qPCR of 17 glia related genes in the dorsolateral prefrontal cortex (DLPFC) and the anterior cingulate cortex (ACC) between 24 patients with MDD and 12 well-matched controls without psychiatric or neurological diseases. The MDD group was subdivided into i) MDD who died of suicide (MDD-S) or natural causes (MDD-NS) and ii) MDD with or without psychotic features (MDD-P and MDD-NP). The results were followed up with confounder factor analysis.

RESULTS

Astrocyte gene aldehyde dehydrogenase-1 L1 (ALDH1L1) showed an increased expression in the DLPFC of MDD-NS and the ACC of MDD-NP. S100 calcium-binding protein B (S100B) was upregulated in the DLPFC of MDD compared to the controls. Microglial markers CD11B and purinergic receptor 12 (P2RY12) both showed decreased expression in the ACC of MDD-NS. CD68 was increased in the DLPFC of MDD in both, MDD-S and MDD-P, compared to the controls. In addition, there was increased translocator protein (TSPO) expression in the DLPFC of MDD, especially MDD-NS. In the ACC, this gene had a lower expression in MDD-P than in MDD-NP. Myelin basic protein (MBP) mRNA in the DLPFC increased in MDD, in relation to psychotic features, but not to suicide.

LIMITATIONS

Sample volumes are relatively small.

CONCLUSIONS

Different glial functions in MDD were related to specific brain area, suicide or psychotic features.

Potential usefulness of complete blood count parameters and inflammatory ratios as simple biomarkers of depression and suicide risk in drug-naive, adolescents with major depressive disorder

We determined whether an elevated neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and monocyte-to-lymphocyte ratio (MLR) were associated with depression in major depressive disorder (MDD), or suicide risk in MDD patients. A total of 137 adolescents with MDD who were antidepressant-naïve and 56 healthy controls (HC) were included. Recent suicidal behaviors were assessed. The NLR, PLR, and MLR were calculated from parameters obtained from a routine complete blood cell count parameters and compared between the MDD subgroups and HC. Cohen's d was calculated as a measure of effect size. The linear relationship between biomarkers with depression severity or suicidality severity was also analysed. Changes in CBC parameters and inflammatory ratios appeared to be more closely related to the suicidality severity than depressive severity. As compared with HC, the WBC count, neutrophil percentage, platelet count, NLR, and PLR were higher in MDD, whereas the lymphocyte percentage was lower. As compared to non-suicidal ideation (non-SI) MDD and HC, the lymphocyte percentage was decreased in MDD with suicidal attempts (SA), whereas monocyte count and MLR were increased. Suicidal attempts in MDD patients were associated with the lower lymphocytes percentage, as well as the elevated monocyte count and MLR.

Comorbid major depression in first-episode drug-naïve patients with schizophrenia: Analysis of the Depression in Schizophrenia in China (DISC) study

BACKGROUND

Depression is very common in patients with schizophrenia, but few studies have investigated the diagnosed major depressive episode (MDE) in first episode and drug naive (FEDN) schizophrenia. To our best knowledge, this is the first large sample study to examine the prevalence, clinical correlates and associated factors of diagnosed MDE in FEDN schizophrenia, as well as the relationship between depressive symptoms and psychopathological symptoms in these schizophrenia patients.

METHODS

A total of 996 FEDN schizophrenia patients were recruited. The 17-item Hamilton Depression Rating Scale (HAMD17) and Positive and Negative Syndrome Scale (PANSS) were used to assess the severity of depression and psychopathology, respectively.

RESULTS

Our results demonstrated that MDE coexisted in nearly half (49.30%) of FEDN schizophrenia patients. Male gender, smoking, PANSS general psychopathology and early age of onset were associated with MDE in patients with FEDN schizophrenia (all p<0.05). In schizophrenia patients with MDE, oridinal logistic regression showed that men (OR=6.65, 95%CI: 4.12-10.45, p<0.001) and smoking (OR=1.94, 95%CI: 1.25-3.01, p=0.003) were positively associated with severity category of depression (all p<0.05), while multivariate regression showed that HAMD17 total score was significantly associated with the PANSS general psychopathology (B=0.06, t=2.72, p=0.007) and total scores (B=0.04, t=2.57, p=0.01).

CONCLUSION

Our study shows that the prevalence of comorbid MDE is high in FEDN schizophrenia patients. Some demographic and clinical variables are associated with the severity of depression in these schizophrenia patients.

Effects of antidepressant drug therapy with or without physical exercise on inflammatory biomarkers in major depressive disorder: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

To conduct a systematic review and meta-analysis of the effects of antidepressant drug therapy (with or without physical exercise) on peripheral inflammatory markers in patients with major depressive disorder (MDD).

METHODS

MEDLINE, PyscINFO, Embase, and Google Scholar databases were searched until May 2020. Randomized trials that measured at least one inflammatory biomarker and included adult outpatients with MDD under antidepressant drug therapy (any drug) with or without physical exercise (any modality) were eligible. Results were summarized using the standardized mean difference (SMD) with 95% confidence intervals (95% CI) under a random-effects model. The Cochrane risk of bias tool (2010) was used to evaluate the risk of bias in the included trials.

RESULTS

Sixty-three trials were identified, encompassing data from 3482 patients, and 20 investigated biomarkers. Trials had biases across multiple domains, rising concerns primarily to selection bias/performance bias/detection bias/attrition bias. SMDs between pre- and post-results indicated a significant reduction in the levels of IL-2 (SMD, - 0.25; 95% CI, - 0.41 to - 0.09, P = 0.002), IL-6 (SMD, - 0.19; 95% CI, - 0.35 to - 0.025, P = 0.024), IL-10 (SMD, - 0.32; 95% CI, - 0.57 to - 0.07, P = 0.011), and serum cortisol (SMD, - 0.35; 95% CI, - 0.58 to - 0.12, P = 0.002). Evidence supporting the influence of physical exercise combined with antidepressant drugs on peripheral inflammatory markers in MDD is sparse and heterogeneous.

CONCLUSION

There is some evidence that antidepressant drug therapy is associated with an overall positive reduction in inflammatory markers, but the evidence is heterogeneous. Further research linking how inflammatory biomarkers modulate physiology related to antidepressant response is required.

TRIAL REGISTRATION

CRD42020220735.

Identification of key genes and crucial pathways for major depressive disorder using peripheral blood samples and chronic unpredictable mild stress rat models

BACKGROUND

Accurate diagnosis of major depressive disorder (MDD) remains difficult, and one of the key challenges in diagnosing MDD is the lack of reliable diagnostic biomarkers. The objective of this study was to explore gene networks and identify potential biomarkers for MDD.

METHODS

In the present study, we performed a comprehensive analysis of the mRNA expression profiles using blood samples of four patients with MDD and four controls by RNA sequencing. Differentially expressed genes (DEGs) were screened, and functional and pathway enrichment analyses were performed using the Database for Annotation, Visualization, and Integrated Discovery. All DEGs were inputted to the STRING database to build a PPI network, and the top 10 hub genes were screened using the cytoHubba plugin of the Cytoscape software. The relative expression of 10 key genes was identified by quantitative real-time polymerase chain reaction (qRT-PCR) of blood samples from 50 MDD patients and 50 controls. Plasma levels of SQSTM1 and TNFα were measured using an enzyme-linked immunosorbent assay in blood samples of 44 MDD patients and 44 controls. A sucrose preference test was used to evaluate depression-like behavior in chronic unpredictable mild stress (CUMS) model rats. Immunofluorescence assay and western blotting were performed to study the expression of proteins in the brain samples of CUMS model rats.

RESULTS

We identified 247 DEGs that were closely associated with MDD. Gene ontology analyses suggested that the DEGs were mainly enriched in negative regulation of transcription by RNA polymerase II promoter, cytoplasm, and protein binding. Moreover, Kyoto Encyclopedia of Genes and Genomes pathway analysis suggested that the DEGs were significantly enriched in the MAPK signaling pathway. Ten hub genes were screened through the PPI network, and qRT-PCR assay revealed that one and six genes were downregulated and upregulated, respectively; however, SMARCA2, PPP3CB, and RAB5C were not detected. Pathway enrichment analysis for the 10 genes showed that the mTOR signaling pathway was also enriched. A strong positive correlation was observed between SQSTM1 and TNFα protein levels in patients with MDD. LC3 II and SQSTM1 protein levels were increased in the CUMS rat model; however, p-mTOR protein levels were decreased. The sucrose preference values decreased in the CUMS rat model.

CONCLUSIONS

We identified 247 DEGs and constructed an MDD-specific network; thereafter, 10 hub genes were selected for further analysis. Our results provide novel insights into the pathogenesis of MDD. Moreover, SQSTM1, which is related to autophagy and inflammatory reactions, may play a key role in MDD. SQSTM1 may be used as a promising therapeutic target in MDD; additionally, more molecular mechanisms have been suggested that should be focused on in future in vivo and in vitro studies.

TNF-α Increase in a Cohort of Depressive Patients

Background

The model of neuroinflammation has been proposed as a possible explanation of depression. Investigations of serum levels of tumor necrosis factor-α (TNF-α) in depressed patients have previously shown contradictory results of increased and decreased levels of TNF-α during the treatment of depression.

Methods

We compared the serum levels of TNF-α in two cohorts of patients suffering from depression (ICD-10 criteria): one cohort from a psychotherapeutic unit (n = 18), where patients were treated with Cognitive Behavioral Analysis System of Psychotherapy (CBASP), and the other cohort from a psychiatric day care unit (n = 16). Both cohorts were investigated at the beginning and at the end of treatment. The intensity of depression was measured by means of the Beck Depression Inventory, 2nd edition (BDI-II) at both time points.

Results

We observed a statistically significant increase of TNF-α in the psychotherapeutic unit at time point 2 compared to time point 1 (T = -14.71, p < 0.001), but not in the psychiatric day care unit. In both cohorts, BDI-II scores at time point 2 were significantly decreased compared to time point 1 (psychiatric day care unit: T = 3.32, p = 0.005; psychotherapeutic unit: T = 6.22, p < 0.001). There was a significant correlation in the psychotherapeutic unit at time point 2 (r = -0.682, p = 0.02).

Conclusion

As TNF-α was increased at time point 2 in the psychotherapeutic unit but not in patients of the psychiatric day care unit, we propose the different durations of pretreatments in both cohorts and the associated processes of neuroinflammation as a possible explanation for our results. The lack of information about the time course of TNF-α in depression could in general explain the huge variety of TNF-α levels in different cohorts of depressed patients reported in the literature.

Major Depressive Disorder: Advances in Neuroscience Research and Translational Applications

Major depressive disorder (MDD), also referred to as depression, is one of the most common psychiatric disorders with a high economic burden. The etiology of depression is still not clear, but it is generally believed that MDD is a multifactorial disease caused by the interaction of social, psychological, and biological aspects. Therefore, there is no exact pathological theory that can independently explain its pathogenesis, involving genetics, neurobiology, and neuroimaging. At present, there are many treatment measures for patients with depression, including drug therapy, psychotherapy, and neuromodulation technology. In recent years, great progress has been made in the development of new antidepressants, some of which have been applied in the clinic. This article mainly reviews the research progress, pathogenesis, and treatment of MDD.

Time-Specific Associations of Tumor Necrosis Factor-α Levels and Polymorphisms (-850 C/T or -308 G/A) With Suicidal Ideation in Acute Coronary Syndrome Patients

Background: Considering the association of inflammation with suicide and acute coronary syndrome (ACS), we investigated the individual and interactive effects of serum tumor necrosis factor-alpha (sTNFα) levels and two polymorphisms (-850 C/T and -308 G/A) on suicidal ideation (SI) after ACS. Methods: The SI status using items on the Montgomery-Åsberg Depression Rating Scale (MADRS), related covariates including sociodemographic and clinical characteristics, sTNFα levels, and tumor necrosis factor-alpha (TNF-α) polymorphisms were evaluated in 969 patients within 2 weeks after ACS. Of the patients, 711 were evaluated 1 year later for SI. Multivariate logistic regression models were used to calculate individual and interactive associations after adjusting for the covariates. Results: Higher (vs. lower) sTNFα levels and the -850 C/T or T/T (vs. C/C) polymorphism were significantly associated with SI 2 weeks after ACS, while only higher sTNFα levels were significantly associated with SI after 1 year. Significant interactive effects were detected between sTNFα (higher) levels and the -850 C/T (C/C or C/T) polymorphism on SI 2 weeks after ACS and between the two (-850 CC or CT and -308 G/A or AA) polymorphisms on SI 1 year after ACS. Conclusions: The sTNFα level and two polymorphisms (-850C/T and -308 G/A), separately or in combination, could be time-specific biomarkers for SI in ACS. Focused interventions for ACS patients at risk of SI might reduce the suicidal burden in patients with ACS.

The anti-inflammatory role of SSRI and SNRI in the treatment of depression: a review of human and rodent research studies

RATIONALE

Depression has the topmost prevalence of all psychiatric diseases. It is characterized by a high recurrence rate, disability, and numerous and mostly unclear pathogenic mechanisms. Besides the monoamine or the neurotrophic hypothesis of depression, the inflammatory mechanism has begun to be supported by more and more evidence. At the same time, the current knowledge about the standard treatment of choice, the selective serotonin reuptake inhibitors (SSRIs) and serotonin and noradrenaline reuptake inhibitors (SNRIs), is expanding rapidly, adding more features to the initial ones.

OBJECTIVES

This review summarizes the in vivo anti-inflammatory effects of SSRIs and SNRIs in the treatment of depression and outlines the particular mechanisms of these effects for each drug separately. In addition, we provide an overview of the inflammation-related theory of depression and the underlying mechanisms.

RESULTS

SSRIs and SNRIs decrease the neuroinflammation through multiple mechanisms including the reduction of blood or tissue cytokines or regulating complex inflammatory pathways: nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), inflammasomes, Toll-like receptor 4 (TLR4), peroxisome proliferator-activated receptor gamma (PPARγ). Also, SSRIs and SNRIs show these effects in association with an antidepressant action.

CONCLUSIONS

SSRIs and SNRIs have an anti-neuroinflammatory role which might contribute the antidepressant effect.

Latent infection, inflammatory markers and suicide attempt history in depressive disorders

BACKGROUND

Numerous reports have described increased rates of exposure to Toxoplasma gondii levels in individuals with a history of suicide attempts in comparison with well controls, or psychiatrically ill individuals, with no suicide attempt history. Such findings suggest that the behavioral effects this parasite exerts on rodent hosts extends to humans though few studies have searched for underlying mechanisms.

METHODS

The present study compared 96 patients with an active depressive disorder and a history of at least two suicide attempts to 126 depressed patients with no history of suicide attempts by IgG and IgM levels of Toxoplasma gondii and cytomegalovirus (CMV). The groups were also compared by IL_1b, TNF-alpha, CRP, IL_6, and IL_1ra titers.

RESULTS

Toxoplasma gondii IgM levels were higher, and seropositivity more likely, in the suicide attempt group. CMV IgG levels were also higher among suicide attempters. Several of these immunoglobulin measures were more robustly associated with the number of suicide attempts than with the dichotomy of suicide attempter and non-attempter. These two antibody levels were also additive in their association with suicide attempter status. IL_1a levels were lower in suicide attempters and correlated negatively with levels of antibodies to Toxoplasma gondii and CMV.

LIMITATIONS

These include a sample size insufficient to explore differences across mood disorder diagnoses or demographic groupings.

CONCLUSIONS

These results indicate that exposure to common infectious agents such as Toxoplasma gondii and CMV are associated with increased risk of suicide attempts but the mechanism of association does not appear to involve the activation of cytokines. Elucidation of the mechanisms which define the relationship between infections and suicide attempts may lead to new methods for the prediction and prevention of suicide attempts.

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.

Peripheral cytokine levels and response to antidepressant treatment in depression: a systematic review and meta-analysis

Predicting antidepressant treatment response has been a clinical challenge for major depressive disorder (MDD). The inflammation hypothesis of depression suggests that cytokines play a key role in the pathophysiology of MDD and alterations in peripheral cytokine levels are associated with antidepressant treatment outcome. Present meta-analysis aimed to examine the association between baseline peripheral cytokine levels and the response to antidepressant treatment and to evaluate whether changes of cytokine levels were associated with the response to antidepressant treatment in patients with MDD. Human-based studies published in any language in peer-reviewed journals were systematically searched from the PubMed, Embase and Web of Science databases, from inception up to October 2018. The search terms included cytokine, depressive disorder and antidepressant and their synonyms. Case-control or case-case studies reporting on levels of IL-1β, IL-2, IL-4, IL-5, IL-6, IL-8, IL-10, IL-12, CRP, TNF-α, IFN-γ, GM-CSF, MIP-1α, and Eotaxin-1 in patients with MDD based on validated depression scales both before and after antidepressant treatment were included. Of 7408 identified records, 44 studies met inclusion. Standardized mean differences in each cytokine were evaluated, and random-effects meta-analyses were performed. MDD patients who responded to antidepressant treatment had lower baseline IL-8 levels than the nonresponders (Hedge's g = -0.28; 95%CI, -0.43 to -0.13; P = 0.0003; FDR = 0.004). Antidepressant treatment significantly decreased levels of TNF-α (Hedge's g = 0.60; 95%CI, 0.26-0.94; P = 0.0006; FDR = 0.004) only in responders, and responders showed significantly more decreased TNF-α levels compared with nonresponders (P = 0.046). These findings suggested that alterations in peripheral cytokine levels were associated with antidepressant treatment outcomes in MDD. Further investigations are warranted to elucidate sources of heterogeneity and examine the potentiality of using inflammatory cytokines as novel predictive markers for the pharmacological treatment of MDD.

Venlafaxine inhibits naloxone-precipitated morphine withdrawal symptoms: Role of inflammatory cytokines and nitric oxide

Opioid-induced neuroinflammation plays a role in the development of opioid physical dependence. Moreover, nitric oxide (NO) has been implicated in several oxidative and inflammatory pathologies. Here, we sought to determine whether treatment with venlafaxine during the development of morphine dependence could inhibit naloxone-precipitated withdrawal symptoms. The involvement of neuro-inflammation related cytokines, oxidative stress, and L-arginine (L-arg)-NO pathway in these effects were also investigated. Mice received morphine (50 mg/kg/daily; s.c.), plus venlafaxine (5 and 40 mg/kg, i.p.) once a day for 3 consecutive days. In order to evaluate the possible role of L-arg-NO on the effects caused by venlafaxine, animals received L-arg, L-NAME or aminoguanidine with venlafaxine (40 mg/kg, i.p.) 30 min before each morphine injection for 3 consecutive days. On 4^th day of experiment, behavioral signs of morphine-induced physical dependence were evaluated after i.p. naloxone injection. Then, brain levels of tissue necrosis factor-alpha (TNF-α), interleukin-1-beta (IL-1β), interleukin-6 (IL-6), interleukin-10 (IL-10), brain-derived neurotrophic factor (BDNF), NO and oxidative stress factors including; total thiol, malondialdehyde (MDA) contents and glutathione peroxidase (GPx) activity were determined. Co-administration of venlafaxine (40 mg/kg) with morphine not only inhibited the naloxone-precipitated withdrawal signs including jumping and weight loss, but also reduced the up-regulation of TNF-α, IL-1β, IL-6, NO and MDA contents in mice brain tissue. However, repeated administration of venlafaxine inhibited the decrease in the brain levels of BDNF, total thiol and GPx. Pre-administration of L-NAME and aminoguanidine improved, while L-arg antagonized the venlafaxine-induced effects. These results provide evidences that venlafaxine could be used as a candidate drug to inhibit morphine withdrawal through the involvement of inflammatory cytokines and l-arginine-NO in mice.

Resolution of new daily persistent headache by a tumor necrosis factor alpha antagonist, Venlafaxine

New daily persistent headache is a continuous, unremitting headache, notorious for its unresponsiveness to aggressive medical interventions. The underlying pathophysiology of new daily persistent headache is poorly understood resulting in unending, chronic pain. However, a prior study identified elevated tumor necrosis factor alpha within the cerebral spinal fluid of new daily persistent headache patients. Herein, we report on a patient who suffered with headache for 6 years failing to respond to over 20 different medical treatments, but found drastic improvement and eventual resolution with Venlafaxine. This drug binds to the 5-HT_2A receptor inhibiting tumor necrosis factor alpha signaling. Therefore, we hypothesize a chronic inflammatory mechanism driving new daily persistent headache pathology.

Effects of omega-3 fatty acids on metabolic syndrome in patients with schizophrenia: a 12-week randomized placebo-controlled trial

RATIONALE

Individuals with schizophrenia are at increased risk of developing metabolic syndrome (MetS) due to their lifestyle and antipsychotic treatment. Our previous study showed that patients with both schizophrenia and MetS present an increased expression and production of tumor necrosis factor-alpha (TNF-alpha). Omega-3 fatty acids have a documented role in suppressing TNF-alpha; therefore, we hypothesized that they may be of value in relieving inflammation and improving metabolic disturbance in patients with both schizophrenia and MetS.

OBJECTIVES

This study employed a randomized placebo-controlled trial to investigate the effects of omega-3 fatty acids on MetS in patients with schizophrenia.

METHODS

We recruited 80 patients with both schizophrenia and MetS who received long-term olanzapine monotherapy. The patients were randomly assigned to the OMG-3 group (n = 40) or the placebo group (n = 40).

RESULTS

Patients with both schizophrenia and MetS had significantly higher levels of TNF-alpha than the control subjects (Z = - 4.37, P < 0.01). There was a significant correlation between omega-3 fatty acid treatment and reduced triglyceride (TG) levels (F_{group × time} = 13.42; df = 1, 66; P < 0.01) when the patients completed this study. Along with metabolic improvement, omega-3 fatty acids decreased TNF-alpha levels after 12 weeks of treatment (F_{group × time} = 6.71; df = 1, 66; P = 0.012). We also found that the extent of TNF-alpha decrease was significantly correlated with that of TG decrease (r = 0.38, P = 0.001).

CONCLUSIONS

Our findings provide suggestive evidence that omega-3 fatty acids have beneficial effects on TG metabolism in patients with both schizophrenia and MetS that parallel decreased inflammation levels.

Impact, Diagnosis, Phenomenology, and Biology

This section provides summaries of the epidemiology, phenomenology, nosology, and the suspected biological substrates of the depressive disorders. It particularly emphasizes the historical evolution of the pertinent diagnostic constructs and the prognostic import both of the various diagnostic groupings and of the individual symptoms and symptom clusters.

Aggression, impulsivity and inflammatory markers as risk factors for suicidal behavior

BACKGROUND

Increased inflammatory markers have been linked to suicidal behavior in numerous studies. Measures of aggression and of impulsivity also comprise risks factors for suicidal behavior and there is evidence that inflammatory markers correlate with these traits. The following analyses compare suicide attempters and non-attempters to determine whether inflammatory markers mediate relationships between aggression or impulsivity and proclivities to suicidal behavior.

METHODS

Investigators at three academic centers recruited patients in major depressive episodes who had a history of two or more suicide attempts (n = 79), or who had no history of suicide attempts (n = 123). Analyses compared these groups by five inflammatory marker levels and by measures of aggression and of impulsivity.

RESULTS

These results did not confirm the hypotheses that cytokine levels would explain relationships between aggressive behavior and suicide attempt history. However, scores for aggressive behavior and for impulsivity were significantly higher among suicide attempters. One of five of the inflammatory markers, (IL-1β), distinguished the two groups with lower values in the suicide attempt group. IL-1β levels correlated inversely with measures of aggression but neither impulsivity or aggressive behavior appear to explain the association between IL-1β levels and suicide attempt status.

CONCLUSION

These results identify recent aggressive behavior, higher levels of impulsivity, and lower levels of IL-1β as risk factors for a history of multiple suicide attempts in a group suffering from major depressive episodes. These measures appear to be additive in their effects.

Different levels of pro- and anti-inflammatory cytokines in patients with unipolar and bipolar depression

BACKGROUND

Immune system dysregulation is critical in the physiopathology of major depressive disorder (MDD) and bipolar disorder (BD). However, it is unclear whether both diseases present the same inflammatory patterns during depressive episodes. We explored the differences in pro- and anti-inflammatory cytokines between unipolar and bipolar depression (BDD) and the trajectory of these cytokines after acute-phase treatment.

METHODS

Sixty-four MDD patients, 61 BDD patients, and 62 healthy controls (HCs) were enrolled. We assessed the clinical features and cytokines plasma levels at baseline and week 12. The pro-inflammatory cytokines (IL-6, TNF-α) and anti-inflammatory cytokines (IL-4, IL-13) of all subjects were assessed by multiplexed sandwich ELISA-based quantitative arrays.

RESULTS

Before acute-phase treatment, the initial levels of TNF-α and IL-13 were significantly lower in the BDD patients than in the MDD patients. The results demonstrated that there was no relationship between each cytokine level and clinical features of unipolar and bipolar depressions. After 12 weeks, TNF-α, IL-4, and IL-13 levels became lower in MDD patients than in the other two groups regardless of the patients' response to treatment while the levels of TNF-α and IL-4 increased only in the BDD responders.

LIMITATIONS

The effects of different drugs on inflammatory cytokines in MDD or BDD could not be explored further due to the relatively small sample size.

CONCLUSION

Even within the same depressive states, MDD and BDD patients present different inflammatory features, particularly in regard to pro-inflammatory TNF-α and anti-inflammatory IL-13. In addition, the fluctuations of cytokines induced by medication may provide a hint regarding the prediction of treatment response.

Effect of antidepressant treatment on peripheral inflammation markers - A meta-analysis

INTRODUCTION

Major Depressive Disorder (MDD) in accordance to the inflammatory concept is associated with complex immunological disturbances in the central nervous system (CNS). This is reflected by elevated plasma levels of inflammatory cytokines in depressed subjects. Although numerous studies report significant influence of antidepressants on pro-inflammatory/anti-inflammatory cytokines balance, the available data is often inconsistent regarding specific cytokines and drugs used. We aimed to perform a comprehensive meta-analysis of the effect of antidepressant treatment on a wide array of cytokines.

METHODS

We performed a systematic search of 6 databases, which yielded 32 studies measuring the levels of selected cytokines before and at a second time-point during antidepressant treatment. For meta-analysis of selected studies with a continuous measure we analysed variables containing the number of cases, mean and standard deviation of the level of IL-1ß, IL-2, IL-5, IL-6, IL-8, IL-10, CRP, TNF-α, IFN-γ levels observed in the different studies, in the intervention groups before and after antidepressant treatment.

RESULTS

Statistical analysis revealed significant decreases of IL-4, IL-6, and IL-10 in MDD subjects after antidepressant treatment. In case of IL-1ß the decrease was significant exclusively for SSRI drugs. We did not find any significant effect of antidepressant medication on IL-2, TNF-α IFN-γ and CRP.

CONCLUSIONS

Antidepressant treatment affects the levels of cytokines in depression. The immunological imbalance in MDD is complex and seems to be mediated by other factors yet to be elucidated. The credibility of our results is limited by high heterogeneity among studies and very few studies with a placebo-controlled design. Research with MDD subtypes, response to treatment status and cytokine associations with the kynurenine pathway taken into account pose a promising target for future studies.

Differences in immunomodulatory properties between venlafaxine and paroxetine in patients with major depressive disorder

Inflammatory processes play a crucial role in the pathophysiology of depression, and identifying the specific cytokines targeted by different antidepressants is important for personalized treatment. The aims of this study were to examine whether venlafaxine and paroxetine cause different immunomodulatory effects when used to treat patients with major depression and to clarify the relationships between plasma cytokine levels and the therapeutic effectiveness of these drugs. A total of 91 Han Chinese patients with major depression completed the 8-week paroxetine or venlafaxine treatment and 90 healthy controls were recruited. A multiplex assay was used to measure cytokines levels in patients with major depression before and after an 8-week venlafaxine and paroxetine treatment. Cytokine levels were measured in healthy controls at the baseline. The 21-item Hamilton Depression Rating Scale was used to assess the changes in psychopathological symptoms from the baseline to the end point in each patient. Venlafaxine treatment caused greater decreases in the levels of interferon gamma (IFN-γ), tumor necrosis factor alpha (TNF-α), interleukin 4 (IL-4), IL-5, IL-1β, and IL-8 than did paroxetine. Paroxetine treatment increased the levels of proinflammatory cytokines IFN-γ, TNF-α, and IL-6 and decreased Th2 cytokine levels. After paroxetine treatment, IL-6 levels increased more in the non-remitter group than in the remitter group. In the remitter group, IL-4 and IL-5 levels decreased to values seen in the healthy controls. After venlafaxine treatment in both the remitter and non-remitter groups, IL-1β levels decreased to values seen in the healthy controls. Our results suggest that venlafaxine and paroxetine have different immunomodulatory properties and that venlafaxine has greater anti-inflammatory effects than paroxetine.

Reduced ENA78 levels as novel biomarker for major depressive disorder and venlafaxine efficiency: Result from a prospective longitudinal study

Although lines of evidence demonstrated that cytokines play an important role in the pathogenesis of major depressive disorder (MDD), none of the them have been established as reliable biomarkers. We use our previous whole-genome cRNA microarray data to identify epithelial cell-derived neutrophil-activating peptide 78 (ENA78), the most differentially expressed cytokine in peripheral blood between MDD patients and healthy controls; and then we confirmed the result by the quantitative reverse transcription-polymerase chain reaction (RT-qPCR) and enzyme-linked immunosorbent assay (ELISA) for mRNA and protein level, respectively, in an independent drug-naïve first-episode sample set. In addition, to replicate the role of plasma ENA 78 in MDD, and determine the role of ENA78 on the venlafaxine efficiency, we further detected the plasma ENA78 in another independent 8- week follow-up sample set. We found that both of mRNA and plasma of ENA78 decreased in MDD patients, and displayed much lower after venlafaxine treatment. We also found that venlafaxine non-responders had lower level of peripheral plasma ENA78 prior to treatment than responders. Our findings for the first time provided strong evidence that the ENA78 may play a key role of mediator in pathogenesis of MDD and in the mechanism of vinlafaxine effects on MDD indicating that reduced ENA78 may be a potential biomarker for diagnosing of MDD and predicting of response to venlafaxine.

Clinical Phenotype of Depression Affects Interleukin-6 Synthesis

Major depressive disorder (MDD) is not a single disease, but a number of various ailments that form one entity. Psychomotor retardation, anhedonia, sleep disorders, an increased suicide risk, and anxiety are the main symptoms that often define the clinical diagnosis of depression. Interleukin-6 (IL-6), as one of the proinflammatory cytokines, seems to be overexpressed during certain mental disorders, including MDD. Overexpression of IL-6 in depression is thought to be a factor associated with bad prognosis and worse disease course. IL-6 may directly affect brain functioning and production of neurotransmitters; moreover, its concentration is correlated with certain clinical symptoms within the wide range of depressive symptomatology. Furthermore, there is a strong correlation between IL-6 synthesis and psychosomatic functioning of the patient. This article discusses potential sources and significance of IL-6 in the pathogenesis of depression.

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.

Pathogenetic and Therapeutic Applications of Tumor Necrosis Factor-α (TNF-α) in Major Depressive Disorder: A Systematic Review

Major depressive disorder (MDD) is characterized by mood, vegetative, cognitive, and even psychotic symptoms and signs that can cause substantial impairments in quality of life and functioning. Up to now, the exact pathogenesis of MDD remains poorly understood. Recent research has begun to reveal that the pro-inflammatory cytokines, particularly, tumor necrosis factor-α (TNF-α), play an integral role in the pathophysiology of depressive disorders and the mechanism of antidepressant treatment. On the base of several observations: it is found that subsets of MDD patients have enhanced plasma levels TNF-α; antidepressant treatments had linked with the decline of TNF-α; central administration of TNF-α gives rise to sickness behavior which shares features with depression; and a blockade of it can ameliorate depressive symptomatology in animal models and clinical trials. In this review article, we focus on recent evidence linking TNF-α and MDD looking at data from animal and clinical studies, illustrating the pathophysiological role, susceptibility and its therapeutic application in depression. We conclude by discussing future directions for research, in particular the opportunities for the development of novel therapeutics that target TNF-α. This will be very important for designing preventative strategies and for the identification of new drug targets and preventative strategies.

Modulatory Effects of Antidepressant Classes on the Innate and Adaptive Immune System in Depression

Current reviews exploring for unique immune-modulatory profiles of antidepressant classes are limited by focusing mainly on cytokine modulation only and neglecting other aspects of the innate and adaptive immune system. These reviews also do not include recent comparative clinical trials, immune-genetic studies and therapeutics with unique neurotransmitter profiles (e. g., agomelatine). This systematic review extends the established literature by comprehensively reviewing the effects of antidepressants classes on both the innate and adaptive immune system. Antidepressants appear, in general, to reduce pro-inflammatory factor levels, particularly C-reactive protein (CRP), tumour necrosis factor (TNF)-α, interleukin (IL)-1β and IL-6. We caution against conclusions as to which antidepressant possesses the greater anti-inflammatory effect, given the methodological heterogeneity among studies and the small number of comparative studies. The effects of antidepressant classes on adaptive immune factors are complex and poorly understood, and few studies have been conducted. Methodological heterogeneity is high among these studies (e. g., length of study, cohort characteristics, dosage used and immune marker analysis). We recommend larger, comparative studies - in clinical and pre-clinical populations.

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.

Cumulative meta-analysis of interleukins 6 and 1β, tumour necrosis factor α and C-reactive protein in patients with major depressive disorder

Cumulative meta-analyses are used to evaluate the extent to which further studies are needed to confirm or refute a hypothesis. We used this approach to assess observational evidence on systemic inflammation in individuals with major depressive disorder. We identified 58 studies of four common inflammatory markers in a literature search of PubMed, Embase and PsychInfo databases in May 2014. Pooled data from the earliest eight studies already showed an association between interleukin-6 concentrations and major depression; 23 more recent studies confirmed this finding (d=0.54, p<0.0001). A significant association between C-reactive protein levels and major depression was noted after 14 studies and this did not change after addition of six more studies (d=0.47, p<0.0001). For these two inflammatory markers, there was moderate heterogeneity in study-specific estimates, subgroup differences were small, and publication bias appeared to be an unlikely explanation for the findings. Sensitivity analyses including only high-quality studies and subjects free of antidepressant medication further verified the associations. While there was a link between tumour necrosis factor-α levels and major depression (d=0.40, p=0.002), the cumulative effect remained uncertain due to the extensive heterogeneity in study-specific estimates and inconsistencies between subgroups. No evidence was found for the association between interleukin-1β levels and major depression (d=-0.05, p=0.86). In conclusion, this cumulative meta-analysis confirmed higher mean levels of interleukin-6 and C-reactive protein in patients with major depression compared to non-depressed controls. No consistent association between tumour necrosis factor-α, interleukin-1β and major depression was observed. Future studies should clarify the specific immune mechanisms involved as well as continue testing anti-inflammatory therapies in patients suffering from major depression.

Meta-Analysis of Cytokines and Chemokines in Suicidality: Distinguishing Suicidal Versus Nonsuicidal Patients

BACKGROUND

Major psychiatric disorders are associated with inflammation. Aberrant cytokine and chemokine levels have been associated with psychiatric disorders and suicidal behavior. We performed a meta-analysis of cytokine and chemokine levels in patients with versus without suicidality and patients with suicidality versus healthy controls.

METHODS

We identified articles by searching MEDLINE, PsycINFO, and Thomson Reuters Web of Knowledge databases and the reference lists of identified studies.

RESULTS

Study inclusion criteria were met by 18 studies comprising 583 patients with suicidality, 315 patients without suicidality, and 845 healthy control subjects. Levels of interleukin (IL)-1β and IL-6 were significantly increased in blood and postmortem brain samples of patients with suicidality compared with both patients without suicidality and healthy control subjects (p < .05 for each). In vitro IL-2 production by peripheral blood mononuclear cells was significantly decreased in patients with suicidality compared with both patients without suicidality and healthy controls (p < .01 for each). Cerebrospinal fluid levels of IL-8 were significantly decreased in patients with suicidality versus control subjects (p < .05).

CONCLUSIONS

We found evidence for aberrant cytokine levels in blood, cerebrospinal fluid, and postmortem brain samples of patients with suicidality. Levels of IL-1β and IL-6 were most robustly associated with suicidality, and these cytokines may help distinguish suicidal from nonsuicidal patients. Rigorously designed longitudinal studies are needed to evaluate these associations further.

A meta-analysis of cytokines in suicidal behavior

BACKGROUND

We conducted the first meta-analysis of studies comparing the plasma and CSF concentrations of cytokines in suicidal patients vs. non-suicidal patients or healthy controls.

METHODS

We searched Medline, Web of Science, and PsycINFO from 1965 to November 2014 for relevant studies. Manual searches of references and unpublished data were also included. Suicidal patients included severe suicide ideators and suicide attempters.

RESULTS

Eleven articles were available for the meta-analysis, for a total sample size of 494 suicidal patients, 497 non-suicidal patients and 398 healthy controls. Levels of 6 independent plasma cytokines (IL2, IL6, TNFalpha, IFNgamma, IL4, TGFbeta) were meta-analyzed for plasma studies comparing suicidal vs. both controls. IL8 level was meta-analyzed for cerebrospinal fluid studies comparing suicidal patients with healthy controls. We reported with medium effect size, that suicidal patients had: (1) lower IL2 plasma levels than both non-suicidal patients and healthy controls (medium effect size); (2) lower IL4 and higher TGFbeta plasma levels than healthy controls.

CONCLUSION

Our results promote the hypothesis of altered inflammatory markers in suicidal patients, for both pro-inflammatory (IL2) and anti-inflammatory (IL4 and TGFbeta) cytokines.

Comparison of stress-induced and LPS-induced depressive-like behaviors and the alterations of central proinflammatory cytokines mRNA in rats

Although proinflammatory cytokine changes in depression have been studied widely, few investigations have searched for specific and common changes in cytokines. In the present study, two animal models of depression were compared: a chronic stress model using forced swim stress and an immune activation model using repeated central lipopolysaccharide (LPS) infusion. The levels of tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 mRNA were examined in the brain regions of the prefrontal cortex, amygdala, and hippocampus using real-time polymerase chain reaction (RT-PCR). It was found that both chronic swim stress and repeated central LPS infusion induced depressive-like behaviors, including decreased body weight, reduced saccharin preference, and increased immobility time or shortened latency of immobility in the tail suspension test. Central TNF-α mRNA expression was elevated in both models and central IL-6 mRNA expression was unchanged in both models. Central IL-1β mRNA expression was increased only in the chronic immune activation model. The findings from this study suggest that TNF-α may be a common risk factor for inflammation in depressive disorders.

The Involvement of TNF-α in Cognitive Dysfunction Associated with Major Depressive Disorder: An Opportunity for Domain Specific Treatments

Major depressive disorder is a highly prevalent, chronic and recurring disorder, associated with substantial impairment in cognitive and interpersonal functions. Accumulating evidence suggests that inflammatory processes play an important role in the etio-pathogenesis, phenomenology, comorbidity and treatment of MDD. Suboptimal remission rates and the persistence of cognitive deficits contribute to functional impairment in MDD inviting the need for the development of mechanistically novel and domain specific treatment approaches. The MEDLINE/ Pubmed database was searched from inception to February, 9th, 2014 with combinations of the following search terms: 'TNF-alpha', 'depression', 'infliximab', 'etanercept', 'adalimumab', 'golimumab' and 'certolizumab'. Preclinical and clinical evidence linking TNF-α to MDD pathophysiology were reviewed as well as the current status of TNF-α modulators as novel agents for the treatment of MDD. Experimental models and clinical studies provide encouraging preliminary evidence for the efficacy of TNF- α antagonists in mitigating depressive symptoms and improving cognitive deficits. Further studies are warranted to confirm these data in larger randomized controlled trials in primary psychiatric populations. Translational research provides a promising perspective that may aid the development and/or repurposing of mechanism-based treatments for depressive symptoms and cognitive impairment in MDD.

Increased plasma levels of soluble TNF receptors 1 and 2 in bipolar depression and impact of lithium treatment

OBJECTIVE

TNF system (TNF and its soluble receptors sTNFR1 and 2) has been investigated as a potential molecular target in bipolar disorder. The aim of the study was to compare plasma levels of these receptors in unmedicated bipolar depressed patients compared with healthy controls, and to evaluate the effects of a 6-week lithium treatment on sTNFR1 and sTNFR2 levels.

METHODS

The study enrolled 29 patients with unmedicated bipolar disorder in a major depressive episode and 27 matched controls. Patients had blood collected at baseline and after 6 weeks of lithium treatment. The concentration of sTNFRs was measured by ELISA.

RESULTS

sTNFR1 and sTNFR2 levels were significantly increased in bipolar depression in comparison with healthy subjects. Lithium treatment did not significantly change sTNFR1 and sTNFR2 levels from baseline to endpoint. There was no correlation between improvement in depressive symptoms and the change in sTNFR1 or sTNFR1 levels.

CONCLUSION

These results reinforce the involvement of an activated immune response system in the pathophysiology of bipolar disorder, with no impact of lithium treatment on the related biomarkers.

Brain-derived neurotrophic factor levels and bipolar disorder in patients in their first depressive episode: 3-year prospective longitudinal study

BACKGROUND

Early identification of patients with bipolar disorder during their first depressive episode is beneficial to the outcome of the disorder and treatment, but traditionally this has been a great challenge to clinicians. Recently, brain-derived neurotrophic factor (BDNF) has been suggested to be involved in the pathophysiology of bipolar disorder and major depressive disorder (MDD), but it is not clear whether BDNF levels can be used to predict bipolar disorder among patients in their first major depressive episode.

AIMS

To explore whether BDNF levels can differentiate between MDD and bipolar disorder in the first depressive episode.

METHOD

A total of 203 patients with a first major depressive episode as well as 167 healthy controls were recruited. After 3 years of bi-annual follow-up, 164 patients with a major depressive episode completed the study, and of these, 21 were identified as having bipolar disorder and 143 patients were diagnosed as having MDD. BDNF gene expression and plasma levels at baseline were compared among the bipolar disorder, MDD and healthy control groups. Logistic regression and decision tree methods were applied to determine the best model for predicting bipolar disorder at the first depressive episode.

RESULTS

At baseline, patients in the bipolar disorder and MDD groups showed lower BDNF mRNA levels (P<0.001 and P = 0.02 respectively) and plasma levels (P = 0.002 and P = 0.01 respectively) compared with healthy controls. Similarly, BDNF levels in the bipolar disorder group were lower than those in the MDD group. These results showed that the best model for predicting bipolar disorder during a first depressive episode was a combination of BDNF mRNA levels with plasma BDNF levels (receiver operating characteristics (ROC) = 0.80, logistic regression; ROC = 0.84, decision tree).

CONCLUSIONS

Our findings suggest that BDNF levels may serve as a potential differential diagnostic biomarker for bipolar disorder in a patient's first depressive episode.

Pro-inflammatory cytokine associated with somatic and pain symptoms in depression

BACKGROUND

More than two-thirds of depressed patients complain of somatic and pain symptoms, which are frequently regarded as a psychological reaction. Although there is a growing body of evidence showing that depression is related to immune abnormalities, few studies have investigated the association between inflammatory cytokines and somatic/pain symptoms.

METHOD

Patients with depressive disorder but without any medical disorders, and age/gender/body mass index (BMI)-matched healthy subjects were enrolled. All the subjects completed the self-rating scales of the Beck Depression Inventory-II and the Depression and Somatic Symptoms Scale, which was comprised of depressive, somatic, and pain subscales. Pro-inflammatory cytokines, including C-reactive protein (CRP), interleukin-2 receptor (sIL-2R), soluble interleukin 6 receptor (sIL-6R), soluble TNF-receptors (sTNF-R), soluble P-selectin (sP-selectin), monocyte chemotactic protein-1 (MCP-1), and adiponectin, were assessed by enzyme-linked immunosorbent assays.

RESULTS

In all, 109 patients with depressive disorder and 126 normal controls were enrolled. The patients with depressive disorder had significantly more severe depression, somatic and pain symptoms (all p<0.001), and higher levels of sIL-2R (p<0.0001), sTNF-R (p<0.001), and sP-selectin (p=0.005) than the normal control group. Using multivariate regression analysis with controlling of age, gender, BMI, and other pro-inflammatory cytokines, sIL-2R was the most significant predictor for depressive symptoms (p<0.0001); with further controlling of severity of depressive symptom, sP-selectin was the only predictor for somatic (p=0.002) and pain (p=0.059) symptoms.

CONCLUSION

The elevated sP-selectin associated with somatic symptoms in depression, may indicate early micro-vascular changes occur subtly, and provide neurobiological evidence for somatic and pain symptom in depression.

The role of inflammatory cytokines in suicidal behavior: a systematic review

There is growing evidence that inflammatory mediators play a critical role in the pathophysiology of both major depression and suicidal behavior. Immunological differences have been reported in both major affective disorders and suicidal behavior. Specifically, increased levels of pro-inflammatory cytokines have been shown to correlate with the severity of depression and various cytokines have been identified as potentially important in understanding the pathophysiology of major affective disorders/suicidality. We aimed to conduct a systematic review of the current literature to investigate the association between inflammatory cytokines and suicidal behavior. Only articles from peer-reviewed journals were selected for inclusion in the present review. Most studies documented the association between suicidality and IL2, IL-6, IL-8, TNF-α and VEGF levels that have been found altered in suicidal behavior. The presence of major depressive disorder (MDD) with suicidal ideation/attempts was associated with differences in inflammatory cytokine profile when compared to that without suicidal ideation/attempts. Most suicide attempters or subjects with suicidal ideation showed an imbalance of the immune system but this does not imply the existence of a causal link. Also, not all studies demonstrated a positive correlation between inflammatory cytokines and suicidal behavior. Further additional studies should elucidate the molecular mechanisms of the immune activation pathways underlying suicidality.