Increase in IL-6 levels among major depressive disorder patients after a 6-week treatment with duloxetine 60 mg/day: a preliminary observation

Anti-inflammatory properties of commonly used psychiatric drugs

Mental health and neurodevelopmental disorders are extremely common across the lifespan and are characterized by a complicated range of symptoms that affect wellbeing. There are relatively few drugs available that target disease mechanisms for any of these disorders. Instead, therapeutics are focused on symptoms and syndromes, largely driven by neurotransmitter hypotheses, such as serotonin or dopamine hypotheses of depression. Emerging evidence suggests that maternal inflammation during pregnancy plays a key role in neurodevelopmental disorders, and inflammation can influence mental health expression across the lifespan. It is now recognized that commonly used psychiatric drugs (anti-depressants, anti-psychotics, and mood stabilizers) have anti-inflammatory properties. In this review, we bring together the human evidence regarding the anti-inflammatory mechanisms for these main classes of psychiatric drugs across a broad range of mental health disorders. All three classes of drugs showed evidence of decreasing levels of pro-inflammatory cytokines, particularly IL-6 and TNF-α, while increasing the levels of the anti-inflammatory cytokine, IL-10. Some studies also showed evidence of reduced inflammatory signaling via nuclear factor- (NF-)κB and signal transducer and activator of transcription (STAT) pathways. As researchers, clinicians, and patients become increasingly aware of the role of inflammation in brain health, it is reassuring that these psychiatric drugs may also abrogate this inflammation, in addition to their effects on neurotransmission. Further studies are required to determine whether inflammation is a driver of disease pathogenesis, and therefore should be a therapeutic target in future clinical trials.

The efficacy and safety of esketamine in the treatment of major depressive disorder with suicidal ideation: study protocol for a randomized controlled trial

BACKGROUND

Major depressive disorder (MDD) is a high risk factor for suicide, with up to 20% of MDD patients attempting suicide during their lifetime. Current treatments for MDD are slow onset of action, low efficiency, and the inability to control suicidal behaviors quickly and effectively. Intravenous ketamine has been shown to have a rapid but transient antidepressant effect, but there is still lack evidence on the efficacy and safety of intravenous esketamine in reducing suicidal ideation and depressive symptoms in MDD patients with suicidal ideation. We designed a study to investigate the effect of short-term repeated intravenous infusion of esketamine three times in MDD patients with suicidal ideation.

METHODS

This study features a randomized, double-blind, placebo-controlled trial (RCT) comparing short-term repeated intravenous infusions of esketamine with placebo as a supplement to conventional antidepressants with an intervention period of 6 days and one infusion every other day, followed by 4 weeks of follow-up. These methods support the examination of the efficacy, safety, tolerability, and mechanism of action of short-term repeated intravenous infusions of esketamine in MDD patients with suicidal ideation.

DISCUSSION

This is the first RCT to explore the efficacy and safety of short-term repeated infusion of esketamine on suicidal ideation and depressive symptoms in MDD patients with suicidal ideation. If proven effective and tolerated, it will provide evidence for rapid and effective treatment of suicidal ideation and depressive symptoms in MDD individuals with suicidal ideation.

TRIAL REGISTRATION

Chinese Clinical Trial Register, ChiCTR2000041232 . Registered 22 December 2020.

Evaluation of Inflammatory Response System (IRS) and Compensatory Immune Response System (CIRS) in Adolescent Major Depression

Purpose

Nowadays, the role of two tightly interconnected systems, the inflammatory response system (IRS) and the compensatory immune response system (CIRS) in depression, is increasingly discussed. Various studies indicate pro-inflammatory activity in adolescent depression; however, there is an almost complete lack of findings about IRS and CIRS balance. Thus, we aimed to assess different IRS and CIRS indices, profiles, and IRS/CIRS ratios in drug-naïve MDD patients at adolescent age, with respect to sex.

Patients and Methods

One hundred MDD adolescents (40 boys, average age: 15.4±1.2 yrs.) and 60 controls (28 boys, average age: 15.3±1.5 yrs.) were examined. Evaluated parameters were 1. plasma levels of interleukin (IL)-1α, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, interferon gamma, tumor necrosis factor alpha (TNF-α), soluble receptor of IL-6 (sIL-6R), soluble receptors of TNF-α (sTNF-R1, sTNF-R2); 2. profiles: IL-6 trans-signaling, M1 macrophage signaling, helper T lymphocytes (Th) 1 profile, regulatory T lymphocytes (Treg)+Th2, allIRS, and allCIRS; 3. IRS vs CIRS activity ratios: TNF-α/TNF-R1, TNF-α/TNF-R2, TNF-α/sTNF-Rs (ie sTNF-R1+sTNF-R2), Th1/Th2, Th1/Treg, Th1/Th2+Treg, M1/Th2, M1/Treg, M1/Treg+Th2, allIRS/allCIRS.

Results

MDD patients showed increased IL-4, IL-10, TNF-α, sIL-6R, Treg+Th2, allIRS, allCIRS, and TNF-α/sTNF-Rs, and decreased Th1/Th2+Treg. MDD females showed increased IL-10 and TNF-α compared to control females. MDD males showed increased IL-4, IL-10, sIL-6R, Treg+Th2, and TNF-α/TNF-R1 compared to control males. Increased sTNF-R1 was found in MDD males compared to MDD females. Positive correlations were found between CDI score and sIL-6R and IL-10 in the total group and between CDI score and IL-10 in adolescent males.

Conclusion

Our study for the first time extensively evaluated IRS and CIRS interactions revealing enhanced pro-inflammatory TNF-α signaling and IL-6 trans-signaling in association with increased IL-10- and IL-4-mediated anti-inflammatory activity in first-episode depression at the adolescent age. Moreover, results reflect the sex-specific simultaneous activation of IRS and CIRS pathways in adolescent depression.

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.

Inflammatory Biomarker and Response to Antidepressant in Major Depressive Disorder: a Systematic Review and Meta-Analysis

Inadequate response to antidepressant treatment, in a significant proportion of patients diagnosed with Major Depressive Disorder, contributes to the large burden of disability associated with the disease; thus, predicting treatment response is one of the most important challenge for clinicians who deal with depressed patients. The cytokine hypothesis of depression suggests that altered pheripheral cytokine levels are involved in the pathophysiology of depressive disorder and in modulating response to treatment. Present meta-analysis aimed to investigate the association between cytokine levels at baseline and response to antidepressant therapies. Authors performed a systematic search of PubMed and Embase databases for studies published between 2010 and January 2021: of 3345 identified records, 31 studies met the inclusion criteria for the qualitative synthesis, whereas 19 studies were eligible for quantitative analysis. Patients who failed to respond to antidepressant had aberrant inflammatory process, namely higher baseline levels of C-Reactive Protein and Interleukine-8, which is associated with treatment outcome in Major Depressive Disorder. Despite these promising results, further investigations are needed in order to replicate the data and to examine the potential role of inflammatory marker as a novel predictive tool for pharmacological treatment of depressive disorder.

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.

Immune-Regulatory and Molecular Effects of Antidepressants on the Inflamed Human Keratinocyte HaCaT Cell Line

Allergic contact dermatitis (ACD) is a T cell-mediated type of skin inflammation resulting from contact hypersensitivity (CHS) to antigens. There is strong comorbidity between ACD and major depression. Keratinocytes release immunomodulatory mediators including pro-inflammatory cytokines and chemokines, which modulate skin inflammation and are crucial cell type for the development of CHS. Our previous studies showed that fluoxetine and desipramine were effective in suppressing CHS in different mouse strains. However, the immune and molecular mechanisms underlying this effect remain to be explored. The aim of the current study was to determine the immune and molecular mechanisms of action of antidepressant drugs engaged in the inhibition of CHS response in the stimulated keratinocyte HaCaT cell line. The results show that LPS, TNF-α/IFN-γ, and DNFB stimulate HaCaT cells to produce large amounts of pro-inflammatory factors including IL-1β, IL-6, CCL2, and CXCL8. HaCaT stimulation was associated with increased expression of ICAM-1, a cell adhesion molecule, and decreased expression of E-cadherin. Imipramine, desipramine, and fluoxetine suppress the production of IL-1β, CCL2, as well as the expression of ICAM-1. LPS and TNF-α/IFN-γ activate p-38 kinase, but antidepressants do not regulate this pathway. LPS decreases E-cadherin protein expression and fluoxetine normalizes these effects. In summary, the antidepressant drugs examined in this study attenuate the stimulated secretion of pro-inflammatory cytokines, chemokines, and modulate adhesion molecule expression by the HaCaT cell line. Therefore, antidepressants may have some clinical efficacy in patients with ACD and patients with comorbid depression and contact allergy.

Impact of Stress on Epilepsy: Focus on Neuroinflammation-A Mini Review

Epilepsy, one of the most common neurological disorders worldwide, is characterized by recurrent seizures and subsequent brain damage. Despite strong evidence supporting a deleterious impact on seizure occurrence and outcome severity, stress is an overlooked component in people with epilepsy. With regard to stressor duration and timing, acute stress can be protective in epileptogenesis, while chronic stress often promotes seizure occurrence in epilepsy patients. Preclinical research suggests that chronic stress promotes neuroinflammation and leads to a depressive state. Depression is the most common psychiatric comorbidity in people with epilepsy, resulting in a poor quality of life. Here, we summarize studies investigating acute and chronic stress as a seizure trigger and an important factor that worsens epilepsy outcomes and psychiatric comorbidities. Mechanistic insight into the impact of stress on epilepsy may create a window of opportunity for future interventions targeting neuroinflammation-related disorders.

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.

Inflammatory markers in depression: A meta-analysis of mean differences and variability in 5,166 patients and 5,083 controls

IMPORTANCE

The magnitude and variability of cytokine alterations in depression are not clear.

OBJECTIVE

To perform an up to date meta-analysis of mean differences of immune markers in depression, and to quantify and test for evidence of heterogeneity in immune markers in depression by conducting a meta-analysis of variability to ascertain whether only a sub-group of patients with depression show evidence of inflammation.

DATA SOURCES

Studies that reported immune marker levels in peripheral blood in patients with depression and matched healthy controls in the MEDLINE database from inception to August 29th 2018 were examined.

STUDY SELECTION

Case-control studies that reported immune marker levels in peripheral blood in patients with depression and healthy controls were selected.

DATA EXTRACTION AND SYNTHESIS

Means and variances (SDs) were extracted for each measure to calculate effect sizes, which were combined using multivariate meta-analysis.

MAIN OUTCOMES AND MEASURES

Hedges g was used to quantify mean differences. Relative variability of immune marker measurements in patients compared with control groups as indexed by the coefficient of variation ratio (CVR).

RESULTS

A total of 107 studies that reported measurements from 5,166 patients with depression and 5,083 controls were included in the analyses. Levels of CRP (g = 0.71; 95%CI: 0.50-0.92; p < 0.0001); IL-3 (g = 0.60; 95%CI: 0.31-0.89; p < 0.0001); IL-6 (g = 0.61; 95%CI: 0.39-0.82; p < 0.0001); IL-12 (g = 1.18; 95%CI: 0.74-1.62; p < 0.0001); IL-18 (g = 1.97; 95%CI: 1.00-2.95; p < 0.0001); sIL-2R (g = 0.71; 95%CI: 0.44-0.98; p < 0.0001); and TNFα (g = 0.54; 95%CI: 0.32-0.76; p < 0.0001) were significantly higher in patients with depression. These findings were robust to a range of potential confounds and moderators. Mean-scaled variability, measured as CVR, was significantly lower in patients with depression for CRP (CVR = 0.85; 95%CI: 0.75-0.98; p = 0.02); IL-12 (CVR = 0.61; 95%CI: 0.46-0.80; p < 0.01); and sIL-2R (CVR = 0.85; 95%CI: 0.73-0.99; p = 0.04), while it was unchanged for IL-3, IL-6, IL-18, and TNF α.

CONCLUSIONS AND RELEVANCE

Depression is confirmed as a pro-inflammatory state. Some of the inflammatory markers elevated in depression, including CRP and IL-12, show reduced variability in patients with depression, therefore supporting greater homogeneity in terms of an inflammatory phenotype in depression. Some inflammatory marker elevations in depression do not appear due to an inflamed sub-group, but rather to a right shift of the immune marker distribution.

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.

Plasma levels of IL-6 in patients with untreated major depressive disorder: comparison with catecholamine metabolites

OBJECTIVE

IL-6 and catecholamines play roles in the pathophysiology of major depressive disorder (MDD).

AIM

The present study investigated associations between plasma IL-6 and plasma catecholamine metabolites in patients with MDD.

PARTICIPANTS AND METHODS

A total of 148 patients (male/female 65/83, age 49.5±12.1 years) who met the criteria for MDD based on the Diagnostic and Statistical Manual of Mental Disorders IV and 40 participants as healthy controls (HC; male/female 23/17, age 44.0±10.5 years) were enrolled in the present study. Plasma levels of 3-methoxy-4-hydroxyphenylglycol (MHPG) and homovanillic acid (HVA) were analyzed using high-performance liquid chromatography, and plasma IL-6 levels were measured using ELISA.

RESULTS

No correlations were observed among plasma IL-6 levels, MHPG levels, and HVA levels in patients with MDD. Plasma IL-6 levels in patients with MDD were significantly higher than in the HC. A positive correlation was found between plasma IL-6 levels and Hamilton Rating Scale for Depression-17 scores.

CONCLUSION

No correlations existed between plasma IL-6 levels and plasma catecholamine metabolite levels in patients with MDD, and the severity of depressive state was related to plasma IL-6 levels in MDD.

Interleukin 6 as a pathogenic factor mediating clinical manifestations and a therapeutic target for rheumatic diseases and depressive disorders

The review summarizes current idea on the key role of interleukin 6 (IL-6) in the pathogenesis of rheumatic diseases (RDs) and depressive disorders. It considers in detail the mechanisms by which IL6 induces the clinical and laboratory manifestations of RDs and depression; the influence of precipitating and predisposing stress factors, including childhood mental traumas, which increase the risk of RDs and depression, on IL-6 production. Particular attention is paid to the consideration of prospects for using IL-6 inhibitors in the therapy of depression.

Inflammatory profiles of severe treatment-resistant depression

BACKGROUND

Treatment-resistant depression (TRD) contributes substantially to the burden of mood disorders and is undoubtedly an important subpopulation in whom there are clear unmet treatment needs. Despite a paucity of research focusing specifically on TRD, recent studies indicate that inflammatory activity may be particularly elevated in these patients.

METHODS

36 patients with TRD were investigated longitudinally before and after undertaking a specialist inpatient treatment program. 27 inflammatory proteins were compared between patients and a matched sample of non-depressed controls, as well as between treatment responders and non-responders. Treatment outcomes were calculated from depression severity scores before and after admission, and at a long-term follow-up 3-12 months after discharge.

RESULTS

TRD patients had higher levels of numerous inflammatory proteins than controls, and elevated interleukins 6 and 8, tumour necrosis factor, c-reactive protein and macrophage inflammatory protein-1 were associated with poorer treatment outcomes. A separate set of proteins (either anti-inflammatory in nature or attenuated at baseline) showed increases during treatment, regardless of clinical response. Participants with the greatest elevations in inflammation tended to be older, more cognitively impaired and more treatment-resistant at baseline.

LIMITATIONS

The small sample and large number of comparisons examined in this study must be taken into account when interpreting these results.

CONCLUSIONS

However, this study provides empirical support for theories that more severe, chronic or treatment-resistant depressive disorders are associated with dysregulated inflammatory activity. If a predictor or predictors of response in TRD are established, improved and targeted care might be more reliably provided to this vulnerable population.

Dl-3-n-Butylphthalide improves lipopolysaccharide-induced depressive-like behavior in rats: involvement of Nrf2 and NF-κB pathways

RATIONALE AND OBJECTIVES

Dl-3-n-Butylphthalide (NBP), a small molecule compound extracted from the seeds of Apium graveolens, possesses a large range of biological effects. Here, we attempted to explore the therapeutic effects of NBP on lipopolysaccharide (LPS)-induced major depressive disorder (MDD) and gain further insight into the underlying mechanisms of the antidepressant effects of NBP.

METHODS

We evaluated the effect of NBP against LPS-induced behavioral changes in rats. We also examined the inflammation, oxidative stress, and apoptosis markers and analyzed the Nrf2 and NF-κB pathways in the hippocampus of rats following repeated peripheral immune challenge by LPS for 2 weeks (500 μg/kg every other day).

RESULTS

Our results indicated that repeated LPS administration induced the rats to a depressive-like state and activated inflammatory response, oxidative stress, and apoptosis reactions in the hippocampus. NBP treatment attenuated the LPS-induced abnormal behavior and ameliorated pathogenic processes in rats with MDD. NBP reduced the inflammatory response with inhibited expression of pro-inflammatory cytokines including IL-1β and IL-6 and downregulated the NF-κB signal pathway. Concurrent with the anti-inflammation action, NBP reduced LPS-induced oxidative reactions in the hippocampus and enhanced Nrf2-targeted signals, as evidenced by increased transcription of antioxidant enzymes and decreased malondialdehyde (MDA) production. In addition, NBP inhibited LPS-induced neuronal apoptosis in the rat brain, as evidenced by decreased apoptosis marker Caspase-3 production and TUNEL assay.

CONCLUSIONS

These results provide more insight into pathogenesis of MDD and firstly demonstrated the potential antidepressant actions of NBP.

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.

Empirically Supported Use of Psychiatric Medications in Adolescents and Adults with IBD

BACKGROUND

The use of psychotropic medications, particularly antidepressants, is common in patients with inflammatory bowel disease (IBD) in spite of a lack of their robust efficacy in this population. This review provides an overview of the use trends of different classes of antidepressant and anti-anxiety medication and their effects on mood, nervous system function, gastrointestinal physiology and immunity drawing from the literature available in the general population, other medical conditions, and when available, patients with IBD. It also covers the evidence base for the actions, efficacy, and potential complications of antidepressants organized by different classes.

METHODS

We conducted a PubMed search of articles relating the different drug classes probed to the terms above in different populations of interest. All types of articles were accepted including case reports and series, open and randomized trials, reviews, and expert opinion. We also examined the reference lists of the publications found.

RESULTS

Selective serotonin reuptake inhibitors (SSRIs) and tricyclic antidepressants (TCAs) are the most commonly prescribed agents for anxiety and depression in patients with IBD, though their efficacy for these conditions in the general population are mild to moderate at best. SSRIs are generally well tolerated, though at higher doses, they, like most antidepressant classes, can be associated with activation, serotonergic syndrome, and increased suicidal ideation. TCAs have many more serious side effects but have some shown efficacy for functional GI symptoms. A newer class, the serotonin noradrenergic reuptake inhibitors (SNRIs), can be effective for refractory depression, anxiety and chronic pain syndromes with a side effect profile similar to both SSRIs and more mild manifestations of TCAs. Mirtazapine has moderate efficacy for depression if sedation and weight gain side effects are tolerated and some small support for use in nausea and vomiting. Bupropion targets dopamine and noradrenaline reuptake and has moderate efficacy for depression, and some small support for use in fatigue and smoking cessation. Buspirone has an indication for generalized anxiety disorder though studies show only a minimal benefit. It has some growing evidence for use in functional dyspepsia. Most of these agents have physiological effects on the brain, immune system, and gastrointestinal tract (with the exception of bupropion) hence their therapeutic and side effects manifested in these systems.

CONCLUSION

Antidepressant medications are frequently prescribed for depression, anxiety disorders, and chronic pain syndromes, but overall support for their efficacy is modest at best. Psychological interventions have growing support for having much more robust effects without the side effects of antidepressants and should be considered first-line treatment or at least an adjunct to psychotropic medications for these conditions.

Effects of psychotropic drugs on inflammation: consequence or mediator of therapeutic effects in psychiatric treatment?

RATIONALE

Current psychotropic medications have been shown to modulate immune activation. However, the effects of individual psychotropic agents on the immune system and how these might contribute to their efficacy remain largely unclear.

OBJECTIVE

This paper aims to review previous literature on the effects of antidepressants and antipsychotics on the immune system, with a systematic review of in vitro findings, and discuss the relevance of these effects for the response to treatment and future drug development.

RESULTS

Inflammatory markers have been associated with fluctuations in clinical status and with treatment response both in depression and psychosis. The in vitro literature on antidepressants shows that some antidepressants, such as clomipramine and fluoxetine, more consistently decrease pro-inflammatory cytokines (interleukin (IL)-6, interferon (IFN)-γ, tumour necrosis factor (TNF)-α), whilst others (mirtazapine and venlafaxine) tend to increase their levels. However, any overall conclusion is challenged by several inconsistent findings, which appear partly dependent on different methodological approaches used. The in vitro studies on antipsychotics are even less clear-cut showing pro- and anti-inflammatory activity for the same antipsychotic agent (haloperidol, clozapine, risperidone) across different studies. We also noted inconsistencies between in vivo and in vitro literature, which could partly be attributed to the interaction in vivo with various biological systems or lifestyle factors that can modulate the immune system.

CONCLUSIONS

Inflammatory markers seem to hold potential for developing more individualised treatment strategies in the future. In this context, further research disentangling the differential immunomodulatory effects of different drugs could be used for tailoring treatment to specific individuals, according to their immune endophenotypes.

Temporal comorbidity of mental disorder and ulcerative colitis

OBJECTIVES

Ulcerative colitis is an inflammatory bowel disease that rarely exists in isolation in affected patients. We examined the association of ulcerative colitis and International Classification of Diseases mental disorder, as well as the temporal comorbidity of three broad International Classification of Diseases groupings of mental disorders in patients with ulcerative colitis to determine if mental disorder is more likely to occur before or after ulcerative colitis.

METHODS

We used physician diagnoses from the regional health zone of Calgary, Alberta, for patient visits from fiscal years 1994 to 2009 for treatment of any presenting concern in that Calgary health zone (763,449 patients) to identify 5113 patients age younger than 1 year to age 92 years (2120 males, average age = 47 years; 2993 females, average age = 48 years) with a diagnosis of ulcerative colitis.

RESULTS

The 16-year cumulative prevalence of ulcerative colitis was 0.0058%, or 58 cases per 10,000 persons (95% confidence interval = 56-60 per 10,000). Although the cumulative prevalence of mental disorder in the overall sample was 5390 per 10,000 (53.9%), we found that 4192 patients with ulcerative colitis (82%) also had a diagnosis of a mental disorder. By annual rate of ulcerative colitis, patients with mental disorder had a significantly higher annual prevalence. The mental disorder grouping neuroses/depressive disorders was most likely to arise before ulcerative colitis (odds ratio = 1.87 for males; 2.24 for females).

CONCLUSIONS

A temporal association was observed between specific groups of International Classification of Diseases mental disorder and ulcerative colitis, indicating a possible etiologic relationship between the disorders or their treatments, or both.

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.

Inflammation and clinical response to treatment in depression: A meta-analysis

The depressive state has been characterised as one of elevated inflammation, which holds promise for better understanding treatment-resistance in affective disorders as well as for future developments in treatment stratification. Aiming to investigate alterations in the inflammatory profiles of individuals with depression as putative biomarkers for clinical response, we conducted meta-analyses examining data from 35 studies that investigated inflammation before and after treatment in depressed patients together with a measure of clinical response. There were sufficient data to analyse IL-6, TNFα and CRP. Levels of IL-6 decreased with antidepressant treatment regardless of outcome, whereas persistently elevated TNFα was associated with prospectively determined treatment resistance. Treatment non-responders tended to have higher baseline inflammation, using a composite measure of inflammatory markers. Our findings suggest that elevated levels of inflammation are contributory to treatment resistance. Combining inflammatory biomarkers might prove a useful tool to improve diagnosis and detection of treatment refractoriness, and targeting persistent inflammation in treatment-resistant depression may offer a potential target for the development of novel intervention strategies.

BDNF plasma levels variations in major depressed patients receiving duloxetine

It has been frequently reported that brain-derived neurotrophic factor (BDNF) plays an important role in the pathophysiology of major depressive disorder (MDD). Objective of the study was to investigate BDNF levels variations in MDD patients during antidepressant treatment with duloxetine. 30 MDD patients and 32 healthy controls were assessed using Hamilton Depression Scale (HAM-D) and monitored for BDNF plasma levels at baseline, week 6 and week 12 of duloxetine treatment (60 mg/day) and at baseline, respectively. According to early clinical response to duloxetine (defined at week 6 by reduction >50 % of baseline HAM-D score), MDD patients were distinguished in early responders (ER) and early non-responders (ENR), who reached clinical response at week 12. Laboratory analysis showed significant lower baseline BDNF levels among patients compared to controls. During duloxetine treatment, in ENR BDNF levels increased, reaching values not significantly different compared to controls, while in ER BDNF levels remained nearly unchanged. Lower baseline BDNF levels observed in patients possibly confirm an impairment of the NEI stress-adaptation system and neuroplasticity in depression, while BDNF increase and normalization observed only in ENR might suggest differential neurobiological backgrounds in ER vs. ENR within the depressive syndrome.

Effectiveness and tolerance of anti-inflammatory drugs' add-on therapy in major mental disorders: a systematic qualitative review

OBJECTIVE

To provide a systematic review of the literature regarding the efficacy of anti-inflammatory drugs in three major mental disorders [major depressive disorder (MDD), schizophrenia and bipolar disorders].

METHOD

Four databases were explored, without any year or language restrictions. The baseline search paradigm was limited to open-labelled clinical and randomized controlled trials (RCTs).

RESULTS

Four major classes of anti-inflammatory drugs were identified, namely polyunsaturated fatty acids (PUFAs), cyclooxygenase (COX) inhibitors, anti-TNFalpha and minocycline. Effectiveness and benefit/risk ratio of each class in MDD, bipolar disorders and schizophrenia was detailed when data were available. Several meta-analyses indicated effectiveness of PUFAs in MDD with a good tolerance profile. One meta-analysis indicated that COX-2 specific inhibitors showed effectiveness in schizophrenia. Anti-TNFalpha showed important effectiveness in resistant MDD with blood inflammatory abnormalities. Minocycline showed effectiveness in schizophrenia.

CONCLUSION

Polyunsaturated fatty acids seem to have the best benefit/risk ratio profile but proved their effectiveness only in MDD. A number of anti-inflammatory drugs are available as adjunct treatment for treatment-resistant patients with MDD, schizophrenia and bipolar disorder. If used with caution regarding their possible side-effects, they may be reasonable therapeutic alternatives for resistant symptomatology.

Targeting classical IL-6 signalling or IL-6 trans-signalling in depression?

INTRODUCTION

Increased IL-6 and soluble IL-6 receptor (sIL-6R) levels in depressed patients was first shown over 20 years ago. The pro-inflammatory effects of IL-6 are predominantly mediated by IL-6 trans-signalling via the sIL-6R, whereas IL-6R membrane signalling has anti-inflammatory effects.

AREAS COVERED

We review data on IL-6 and sIL-6R in inflammation, depression, animal models of depression and the effects of different classes of antidepressants. The biological context for IL-6 trans-signalling as a pathogenic factor in depression involves its role in the acute phase response, disorders in zinc and the erythron, hypothalamic-pituitary-adrenal axis activation, induction of the tryptophan catabolite pathway, oxidative stress, bacterial translocation, transition towards sensitisation, autoimmune processes and neuroprogression and the multicausal aetiology of depression, considering that psychosocial stressors and comorbid immune-inflammatory diseases are associated with the onset of depression.

EXPERT OPINION

The homeostatic functions of IL-6 imply that ubiquitous IL-6 inhibitors, for example, tocilizumab, may not be the optimal treatment target in depression. A more promising target may be to increase soluble glycoprotein 130 (sgp130) inhibition of IL-6 trans-signalling, while allowing the maintenance of IL-6R membrane signalling. Future research should delineate the effects of treatments with sgp130Fc in combination with antidepressants in various animal models of chronic depression.

VEGF plasma level variations in duloxetine-treated patients with major depression

BACKGROUND

The vascular endothelial growth factor (VEGF) signaling, which modulates angiogenesis and neurogenesis within the neurovascular unit, might play an important role in the neuro-endocrine-immune (NEI) stress-adaptation system. Recent evidence suggests that VEGF is involved in the pathophysiology of a number of diseases including major depressive disorder (MDD) and is affected by some treatments, including antidepressants. The objective of the study was to investigate the VEGF level variations in MDD patients during antidepressant treatment with duloxetine, a relatively new SNRI.

METHODS

A total of 30 MDD patients and 32 healthy controls were assessed using the Hamilton Depression Scale (HAM-D) and monitored for VEGF plasma levels at baseline, week 6 and week 12 of duloxetine treatment (60 mg/day) and at baseline, respectively.

RESULTS

According to early clinical response to duloxetine (defined at week 6 by reduction>50% of baseline HAM-D score), the MDD patients were divided into early responders (ER) and early non-responders (ENR). During duloxetine treatment, we found an opposite trend in the VEGF levels between ER and ENR: in ER the VEGF levels significantly increased in association with clinical response at W6, while in ENR the VEGF levels significantly decreased in association with an overall clinical response at W12.

LIMITATIONS

Small sample size.

CONCLUSIONS

The opposite trends in VEGF levels, increasing in ER and decreasing in ENR, might reflect differential Norepinephrine/Serotonin effects of duloxetine on differential neurobiological backgrounds of depressive syndromes. Overall, the modulation of VEGF signaling within the neurovascular unit during antidepressant treatment could hypothetically favor the remodeling of neural circuitry, contributing to adaptive adjustment of the NEI stress-adaptation system.

Dysregulated relationship of inflammation and oxidative stress in major depression

Chronic inflammation and oxidative stress have been implicated in the pathophysiology of Major Depressive Disorder (MDD), as well as in a number of chronic medical conditions. The aim of this study was to examine the relationship between peripheral inflammatory and oxidative stress markers in un-medicated subjects with MDD compared to non-depressed healthy controls and compared to subjects with MDD after antidepressant treatment. We examined the relationships between IL-6, IL-10, and the IL-6/IL-10 inflammatory ratio vs. F2-isoprostanes (F2-IsoP), a marker of oxidative stress, in un-medicated MDD patients (n=20) before and after 8 weeks of open-label sertraline treatment (n=17), compared to healthy non-depressed controls (n=20). Among the un-medicated MDD subjects, F2-IsoP concentrations were positively correlated with IL-6 concentrations (p<0.05) and were negatively correlated with IL-10 concentrations (p<0.01). Accordingly, F2-IsoP concentrations were positively correlated with the ratio of IL-6/IL-10 (p<0.01). In contrast, in the control group, there were no significant correlations between F2-IsoPs and either cytokine or their ratio. After MDD subjects were treated with sertraline for 8 weeks, F2-IsoPs were no longer significantly correlated with IL-6, IL-10 or the IL-6/IL-10 ratio. These data suggest oxidative stress and inflammatory processes are positively associated in untreated MDD. Our findings are consistent with the hypothesis that the homeostatic buffering mechanisms regulating oxidation and inflammation in healthy individuals become dysregulated in untreated MDD, and may be improved with antidepressant treatment. These findings may help explain the increased risk of comorbid medical illnesses in MDD.

Antidepressant therapy in epilepsy: can treating the comorbidities affect the underlying disorder?

There is a high incidence of psychiatric comorbidity in people with epilepsy (PWE), particularly depression. The manifold adverse consequences of comorbid depression have been more clearly mapped in recent years. Accordingly, considerable efforts have been made to improve detection and diagnosis, with the result that many PWE are treated with antidepressant drugs, medications with the potential to influence both epilepsy and depression. Exposure to older generations of antidepressants (notably tricyclic antidepressants and bupropion) can increase seizure frequency. However, a growing body of evidence suggests that newer ('second generation') antidepressants, such as selective serotonin reuptake inhibitors or serotonin-noradrenaline reuptake inhibitors, have markedly less effect on excitability and may lead to improvements in epilepsy severity. Although a great deal is known about how antidepressants affect excitability on short time scales in experimental models, little is known about the effects of chronic antidepressant exposure on the underlying processes subsumed under the term 'epileptogenesis': the progressive neurobiological processes by which the non-epileptic brain changes so that it generates spontaneous, recurrent seizures. This paper reviews the literature concerning the influences of antidepressants in PWE and in animal models. The second section describes neurobiological mechanisms implicated in both antidepressant actions and in epileptogenesis, highlighting potential substrates that may mediate any effects of antidepressants on the development and progression of epilepsy. Although much indirect evidence suggests the overall clinical effects of antidepressants on epilepsy itself are beneficial, there are reasons for caution and the need for further research, discussed in the concluding section.

Might different cytokine trends in depressed patients receiving duloxetine indicate differential biological backgrounds

BACKGROUND

Correlational studies investigating neurohormonal-cytokine modulation by antidepressants suggest, among others, variations in cytokines balances as state markers of different biological subtypes of major depressive disorder (MDD) and response predictors to specific treatments. Objective of the study was to investigate cytokines modulation by duloxetine, a relatively newer SNRI with "clean" dual serotonin/norepinephrine mechanism.

METHODS

30 MDD patients and 32 healthy controls were assessed using Hamilton Depression Scale (HAM-D) and monitored for levels of IL-1β, IL-2, IL-4, IL-10, IL-12, IFN-γ and TNF-α, at baseline, week 6 and week 12 of duloxetine treatment (60mg/day) and at baseline, respectively.

RESULTS

Early responders (ER: defined at week 6 by reduction >50% of baseline HAM-D score) and early non-responders (ENR) showed opposite trends in cytokine levels during duloxetine treatment: ENR were characterized by baseline Th2 shift compared to controls (lower IL-1β, IFN-γ and TNF-α) with increase in Th1 cytokines levels during treatment (increase of IL-1β, IL-12, IFN-γ, IL-1β/IL-10 and TNF-α/IL-10, decrease of IL-10), achieving clinical response at week 12; ER were characterized by baseline Th2-to-Th1 relative switch compared to ENR (higher IL-1β, IL-1β/IL-10 and TNF-α/IL-10) with reduction in Th1 cytokines levels during treatment (decrease of TNF-α and TNF-α/IL-10), achieving clinical response at week 6.

LIMITATIONS

Small sample size.

CONCLUSIONS

In accordance to early clinical response, duloxetine treatment could divide depressed patients into at least 2 subgroups characterized by clinical and laboratory differentiated behavior, suggesting different neurobiological background within depressive syndrome differentially sensitive to different drug components: pro-serotonergic effect and increase in Th1 cytokines in ENR vs. pro-noradrenergic effect and decrease in Th1 cytokines in ER.

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

Although tumor necrosis factor-alpha (TNF-α) has been recognized to be involved in the pathogenesis of major depressive disorder (MDD) for a long time, only few studies so far investigated the effects of antidepressant, venlafaxine on TNF-α and the results are inconsistent. Moreover, the association between plasma TNF-α levels and suicide accompanied with MDD is entirely unknown. To elucidate these relationships, in the present study, 64 first-episode drug-naïve MDD patients and 64 matched healthy controls were recruited. Total 61 MDD patients received 8-week venlafaxine treatment and they were divided into responders and non-responders according to the reduction rate of HRSD-17. Prior to venlafaxine treatment, both responders and non-responders shared a similar plasma TNF-α (p=0.33), which was significantly decreased following venlafaxine treatment (p<0.001, p=0.03, respectively). Compared to non-responders, the responder group had a greater reduction in TNF-α (p=0.01), which was associated with the greater reduction rate of HRSD-17 (B=1.02, p=0.01). In addition, the plasma TNF-α levels were equally higher in both suicidal and non-suicidal MDD patients (p=0.84) compared to the healthy controls on admission (p=0.001, p=0.03, respectively). Together, our data suggest that MDD per se rather than suicide is associated with the elevated plasma TNF-α, which can be inhibited with venlfaxine monotherapy. The extent of TNF-α reduction may be associated with the efficiency of venlafaxine.

Interleukin-6, C-reactive protein and interleukin-10 after antidepressant treatment in people with depression: a meta-analysis

BACKGROUND

Cross-sectional studies support an association between depression and inflammatory markers. However, little is known of their relationship in the context of antidepressant treatment. Our aim was to explore via meta-analysis whether antidepressant treatment is associated with a reduction in three inflammatory markers associated with depression.

METHOD

A computerized search of EMBASE, Medline, PsycINFO and Cochrane Library databases was completed using subject headings for depression and either interleukin-6, C-reactive protein or interleukin-10, selecting studies which reported circulating levels of inflammatory markers before and after antidepressant treatment for people with depression. Outcome and moderator variables were coded for analysis, including inflammatory marker change, depression severity change, age, gender ratio, assay brand, treatment response and weight change.

RESULTS

Pooled effect sizes showed a significant decrease in interleukin-6 (n=14, d=-0.42, p=0.02), marginally significant decrease in C-reactive protein (n=8, d=-0.57, p=0.05) and a non-significant decrease in interleukin-10 (n=3, d=-0.45, p=0.14) after treatment. High levels of heterogeneity were observed, which may be associated with clinical variations between the studies such as weight gain, anxiety, incomplete remission and other individual differences and co-morbidities.

CONCLUSIONS

The findings of this meta-analysis indicate that there may be a normalization of overactive inflammatory processes following antidepressant treatment.

Neuroimmunomodulation in unipolar depression: a focus on chronobiology and chronotherapeutics

The rising burden of unipolar depression along with its often related sleep disturbances, as well as increasing rates of sleep restriction in modern society, make the search for an extended understanding of the aetiology and pathophysiology of depression necessary. Accumulating evidence suggests an important role for the immune system in mediating disrupted neurobiological and chronobiological processes in depression. This review aims to provide an overview of the neuroimmunomodulatory processes involved with depression and antidepressant treatments with a special focus on chronobiology, chronotherapeutics and the emerging field of immune-circadian bi-directional crosstalk. Increasing evidence suggests that chronobiological disruption can mediate immune changes in depression, and likewise, immune processes can mediate chronobiological disruption. This may suggest a bi-directional relationship in immune-circadian crosstalk. Furthermore, given the immunomodulatory effects of antidepressants and chronotherapeutics, as well as their associated beneficial effects on circadian disturbance, we--and others--suggest that these therapeutic agents may exert their chronobiotic effects partially via the neuroimmune system. Further research is required to better elucidate the mechanisms of immune involvement in the chronobiology of depression.

The effect of antidepressant medication treatment on serum levels of inflammatory cytokines: a meta-analysis

Serum levels of inflammatory cytokines, for example, tumor necrosis factor alpha (TNFα), interleukin-6 (IL-6), and IL-1 beta (IL-1β), are elevated in subjects with major depressive disorder (MDD). The reason why this occurs is unclear. Elevated levels of inflammatory cytokines could be a result of brain dysfunction in MDD. It is also possible that inflammatory cytokines contribute to depressive symptoms in MDD. If the first assumption is correct, one would expect levels to normalize with resolution of the depressive episode after treatment. Several studies have measured changes in cytokine levels during antidepressant treatment; however, the results vary. The purpose of this study was to pool all available data on changes in serum levels of TNFα, IL-6, and IL-1β during antidepressant treatment to determine whether these levels change. Studies were included if they used an approved pharmacological treatment for depression, patients had a diagnosis of MDD, and serum levels of TNFα, IL-6, and/or IL-1β were measured before and after treatment. Twenty-two studies fulfilled these criteria. Meta-analysis of these studies showed that, overall, while pharmacological antidepressant treatment reduced depressive symptoms, it did not reduce serum levels of TNFα. On the other hand, antidepressant treatment did reduce levels of IL-1β and possibly those of IL-6. Stratified subgroup analysis by class of antidepressant indicated that serotonin reuptake inhibitors may reduce levels of IL-6 and TNFα. Other antidepressants, while efficacious for depressive symptoms, did not appear to reduce cytokine levels. These results argue against the notion that resolution of a depressive episode is associated with normalization of levels of circulating inflammatory cytokines; however, the results are consistent with the possibility that inflammatory cytokines contribute to depressive symptoms and that antidepressants block the effects of inflammatory cytokines on the brain.