Increased plasma levels of soluble TNF receptor I in patients with bipolar disorder

The Pathophysiological Underpinnings of Gamma-Band Alterations in Psychiatric Disorders

Investigating the biophysiological substrates of psychiatric illnesses is of great interest to our understanding of disorders' etiology, the identification of reliable biomarkers, and potential new therapeutic avenues. Schizophrenia represents a consolidated model of γ alterations arising from the aberrant activity of parvalbumin-positive GABAergic interneurons, whose dysfunction is associated with perineuronal net impairment and neuroinflammation. This model of pathogenesis is supported by molecular, cellular, and functional evidence. Proof for alterations of γ oscillations and their underlying mechanisms has also been reported in bipolar disorder and represents an emerging topic for major depressive disorder. Although evidence from animal models needs to be further elucidated in humans, the pathophysiology of γ-band alteration represents a common denominator for different neuropsychiatric disorders. The purpose of this narrative review is to outline a framework of converging results in psychiatric conditions characterized by γ abnormality, from neurochemical dysfunction to alterations in brain rhythms.

Plasma IGFBP-3 and IGFBP-5 levels are decreased during acute manic episodes in bipolar disorder patients

Introduction: Bipolar disorder (BD) is a recurrent and disabling psychiatric disorder related to low-grade peripheral inflammation and altered levels of the members of the insulin-like growth factor (IGF) family. The aim of this study was to evaluate the plasma levels of IGF-2, insulin-like growth factor-binding protein 1 (IGFBP-1), IGFBP-3, IGFBP-5, IGFBP-7, and inflammatory markers such as tumor necrosis factor α (TNF-α), monocyte chemoattractant protein 1 (MCP-1), and macrophage inflammatory protein 1β (MIP-1β). Methods: We used the Young Mania Rating Scale (YMRS) to determine the severity of the symptomatology, while proteins were measured by enzyme-linked immunosorbent assay (ELISA). We included 20 patients with BD who suffered a manic episode and 20 controls. Some BD patients (n = 10) were evaluated after a period (17 ± 8 days) of pharmacological treatment. Results: No statistical difference was found in IGF-2, IGFBP-1, IGFBP-7, TNF-α, and MIP-1β levels. However, IGFBP-3 and IGFBP-5 levels were found to be statistically decreased in BD patients. Conversely, the MCP-1 level was significantly increased in BD patients, but their levels were normalized after treatment. Intriguingly, only IGFBP-1 levels were significantly decreased after treatment. No significant correlation was found between the YMRS and any of the proteins studied either before or after treatment or between IGF proteins and inflammatory markers. Discussion: To some extent, IGFBP-3 and IGFBP-5 might be further explored as potential indicators of treatment responsiveness or diagnosis biomarkers in BD.

Monoclonal antibody precision therapy targeting inflammation for bipolar disorder: a narrative review

Bipolar disorder (BD) is a severe mental disorder with various hypotheses regarding its pathogenesis. This article provides a summary of numerous studies on the variations in inflammatory cytokine levels in patients with BD and the effects of treatment with antipsychotics, mood stabilizers, and antidepressants on these levels. In addition, patients with autoimmune diseases who use anti-inflammatory monoclonal antibodies experience symptoms, such as depression, anxiety, and insomnia. These pieces of evidence suggest a potential association between immune inflammation and BD and offer new possibilities for therapy. Building upon this relationship, the authors propose an innovative approach for treating BD through individualized and precise therapy using anti-inflammatory monoclonal antibody drugs. To support this proposal, the authors compile information on pharmacological effects and relevant studies, including trials of various anti-inflammatory therapeutic monoclonal antibody drugs (e.g. infliximab, tocilizumab, and canakinumab) for the potential treatment of BD and its associated side effects in psychiatry. The authors categorize these anti-inflammatory monoclonal antibody drugs into levels I-IV through a comprehensive analysis of their advantages and disadvantages. Their potential is examined, and the need for further exploration of their pharmaceutical effects is established.

Increased prefrontal cortical cells positive for macrophage/microglial marker CD163 along blood vessels characterizes a neuropathology of neuroinflammatory schizophrenia

Transcript levels of cytokines and SERPINA3 have been used to define a substantial subset (40%) of individuals with schizophrenia with elevated inflammation and worse neuropathology in the dorsolateral prefrontal cortex (DLPFC). In this study, we tested if inflammatory proteins are likewise related to high and low inflammatory states in the human DLFPC in people with schizophrenia and controls. Levels of inflammatory cytokines (IL6, IL1β, IL18, IL8) and a macrophage marker (CD163 protein) were measured in brains obtained from the National Institute of Mental Health (NIMH) (N = 92). First, we tested for diagnostic differences in protein levels overall, then we determined the percentage of individuals that could be defined as "high" inflammation using protein levels. IL-18 was the only cytokine to show increased expression in schizophrenia compared to controls overall. Interestingly, two-step recursive clustering analysis showed that IL6, IL18, and CD163 protein levels could be used as predictors of "high and low" inflammatory subgroups. By this model, a significantly greater proportion of schizophrenia cases (18/32; 56.25%; SCZ) were identified as belonging to the high inflammatory (HI) subgroup compared to control cases (18/60; 30%; CTRL) [χ2(1) = 6.038, p = 0.014]. When comparing across inflammatory subgroups, IL6, IL1β, IL18, IL8, and CD163 protein levels were elevated in both SCZ-HI and CTRL-HI compared to both low inflammatory subgroups (all p < 0.05). Surprisingly, TNFα levels were significantly decreased (-32.2%) in schizophrenia compared to controls (p < 0.001), and were most diminished in the SCZ-HI subgroup compared to both CTRL-LI and CTRL-HI subgroups (p < 0.05). Next, we asked if the anatomical distribution and density of CD163+ macrophages differed in those with schizophrenia and high inflammation status. Macrophages were localized to perivascular sites and found surrounding small, medium and large blood vessels in both gray matter and white matter, with macrophage density highest at the pial surface in all schizophrenia cases examined. A higher density of CD163+ macrophages, that were also larger and more darkly stained, was found in the SCZ-HI subgroup (+154% p < 0.05). We also confirmed the rare existence of parenchymal CD163+ macrophages in both high inflammation subgroups (schizophrenia and controls). Brain CD163+ cell density around blood vessels positively correlated with CD163 protein levels. In conclusion, we find a link between elevated interleukin cytokine protein levels, decreased TNFα protein levels, and elevated CD163+ macrophage densities especially along small blood vessels in those with neuroinflammatory schizophrenia.

Comparison of Executive Dysfunction, Proinflammatory Cytokines, and Appetite Hormones Between First-Episode and Multiple-Episode Bipolar Disorder

Background

Evidence has demonstrated associations of bipolar disorder (BD) with cognitive impairment, dysregulated proinflammatory cytokines, and appetite hormones.

Aim

To compare executive dysfunction, proinflammatory cytokines, and appetite hormones between patients with first-episode and multiple-episode BDs.

Methods

This cross-sectional study included young adults aged 18 to 39 years who were diagnosed as having type 1 BD in the first or recurrent episode and a group of age-/sex-matched healthy controls. Data regarding patient characteristics, clinical symptoms, cytokines (C-reactive protein [CRP], interleukin-6, and tumor necrosis factor [TNF]-α), appetite hormones (leptin, adiponectin, ghrelin, and insulin), and executive function evaluated using the Wisconsin Card Sorting Test (WCST) were collected.

Results

A total of 112 participants (38 patients in the multiple-episode BD group, 31 patients in the first-episode BD group, and 43 in the control group) were included. Multivariate analysis revealed that patients in the multiple-episode BD group performed significantly worse in the WCST (P < .05) and had higher levels of ghrelin (P = .002), and lower levels of CRP (P = .040) than those in the first-episode BD group. Patients with BD had significantly higher TNF-α and ghrelin levels compared with the healthy controls. No significant associations of CRP, TNF-α, and ghrelin levels with executive function were observed.

Conclusions

Profiles in proinflammatory cytokines and appetite hormones as well as executive function significantly differed between patients with first-episode and multiple-episode BDs and controls, which may suggest their potential roles in the clinical stages and pathophysiology of type 1 BD.

Cognition-immune interactions between executive function and working memory, tumour necrosis factor-alpha (TNF-alpha) and soluble TNF receptors (sTNFR1 and sTNFR2) in bipolar disorder

OBJECTIVES

This study examined cognition-immune interactions, specifically executive function, working memory, peripheral levels of tumour necrosis factor-alpha (TNF-α), and soluble tumour necrosis factor receptors-1 and -2 (sTNFR1 and 2) levels in bipolar disorder (BD) patients in comparison with controls.

METHODS

Thirty-one BD participants and twenty-seven controls participated in the study. The neurocognitive assessment was performed through three of CogState Research Battery^TM tasks for executive function and working memory. Plasma levels of TNF-α, sTNFR1, and sTNFR2 were measured after overnight fasting. Sociodemographic data and symptom severity of depression and mania were assessed.

RESULTS

BD presented a significantly worse performance in the working memory task (p = .005) and higher levels of TNF-α (p = .043) in comparison to controls. A trend level of significance was found for sTNFR1 between groups (p = .082). Among BD participants, there were significant correlations between sTNFR2 and neurocognitive tasks (Groton Maze Learning Task: ρ = .54, p = .002; Set-Shifting Task: ρ = .37, p = .042; and the Two-Back Task: ρ = -.49, p = .005), and between sTNFR1 and mania, depression and anxiety symptoms (respectively ρ = .37, p = .038; ρ = -.38, p = .037; and ρ = .42, p = .002).

CONCLUSION

TNF-α and its receptors might be an important variable in cognitive impairment in BD. Future studies might focus on the development of anti-inflammatory therapeutic targets for cognitive dysfunction in BD.

Are serum levels of inflammatory markers associated with the severity of symptoms of bipolar disorder?

BACKGROUND

To explore the relationship between serum levels of inflammatory markers and symptomatic severity of bipolar disorder (BD).

MATERIALS AND METHODS

A cross-sectional study was conducted on 126 BD patients with current depressive episode (BDD), 102 BD patients with current mixed or (hypo)manic episode (BDM) and 94 healthy controls (HC). All participants were drug-naïve and had no current active physical illness associated with inflammatory response or history of substance abuse. Fasting serum levels of CRP, leptin (LEP), adiponectin (ADP), visfatin (VIS), TNF-α, IL-2, IL-6, IL-10, IL-17), and monocyte chemoattractant protein-1 (MCP-1) were measured with enzyme-linked immunosorbent assay (ELISA). Symptomatic severity of BD was assessed with HAMD-17 and YMRS. Generalized linear model was used to determine the association between the serum levels of inflammatory markers and symptomatic severity of BD.

RESULTS

The serum levels of IL-6, IL-10 and IL-17, and the IL-6/IL-10 ratio were significantly lower in mild BDD than in HC. In moderate BDD, the serum levels of MCP, IL-6 and IL-17 were significantly lower than in HC. In severe BDD, the serum level of ADP, MCP-1, IL-10 and IL-17and the IL-17/IL-10 ratio were significantly lower than in HC. The serum levels of TNF-α and the IL-6/IL-10 ratio were significantly higher in mild BDM than in HC. In moderate BDM, the serum level of VIS, IL-2, and IL-17 were significantly higher than in HC, but the IL-6/IL-10 ratio was significantly lower than in control. In severe BDM, the serum levels of IL-6 and IL-17 and the ratios of IL-6/IL-10 and IL-17/IL-10 were significantly lower than in HC, but the neutrophil/lymphocyte ratio was significantly higher than in HC.

CONCLUSION

In BDD, immune-inhibition is persistently predominant, while in mild-to-moderate BDM, immune system is activated but inhibited in severe BDM. The dynamic change of serum inflammatory markers suggests that alteration of peripheral inflammatory markers in BD is state-dependent instead of trait-marked.

Peripheral levels of C-reactive protein, tumor necrosis factor-α, interleukin-6, and interleukin-1β across the mood spectrum in bipolar disorder: A meta-analysis of mean differences and variability

IMPORTANCE

It is unclear whether differences exist in the magnitude and variability of pro-inflammatory mediators in the different phases of bipolar disorder (BD) and among subjects with BD, as compared to healthy controls.

OBJECTIVE

To run a comparative meta-analysis of C-Reactive Protein (CRP), IL-1, IL-6, TNF-α in BD vs healthy controls, measuring mean and variability effects on all subjects. Sensitivity analyses include disease activity.

DATA SOURCES

Systematic review of observational studies in PubMed and PsycInfo up to February 2nd, 2020.

STUDY SELECTION

Case-control studies reporting inflammatory mediators' levels in BD and controls.

DATA EXTRACTION AND SYNTHESIS

Summary distribution measures of circulating CRP, IL-1β, IL-6, TNF-α in participants with BD and control groups were extracted. Random-effects multivariate meta-analyses were conducted based on individual study/mediator effect sizes (Hedge's g).

MAIN OUTCOMES AND MEASURES

Co-primary outcomes were inflammatory mediators' levels (Hedge's g) and variability (coefficient of variance ratio (CVR)) differences between participants with BD across the mood spectrum and controls.

RESULTS

Out of the initial 729 papers, 72 were assessed and then excluded after full-text review, and ultimately 53 studies were included in the systematic review, while 49 were included in the meta-analysis. The mean age was 36.96 (SD: 9.29) years, and the mean female percentage was 56.31 (SD: 16.61). CRP (g = 0.70, 95% CI 0.31-1.09, k = 37, BD = 2,215 vs HC = 3,750), IL-6 (g = 0.81, 95% CI 0.46-1.16, k = 45, BD = 1,956 vs HC = 4,106), TNF-α (g = 0.49, 95% CI 0.19-0.78, k = 49, BD = 2,231 vs HC = 3,017) were elevated in subjects with BD vs HC, but not IL-1β (g = -0.28, 95% CI -0.68-0.12, k = 4, BD = 87 vs HC = 66). When considering euthymic, depressive, and manic episodes separately, CRP and TNF-α were elevated in both depressive and manic episodes, but not in euthymia, while IL-6 remained elevated regardless of the disease state. No difference in CVR emerged for CRP, IL-1β, and TNF-α, while a lower CVR was observed for IL-6. When considering disease phases, CVR was higher in BD than in HCs for CRP during depressive episodes, lower for IL-6 during euthymia, and higher during manic episodes for CRP, IL-6, and TNF-α. Sensitivity analyses after excluding outliers identified with funnel plot visual inspection, low-quality studies, and considering only studies matched per body mass index confirmed the main results. Meta-regression showed that age (IL-6, TNF-α), gender (CRP), duration of illness (CRP) moderated elevated individual inflammatory levels.

CONCLUSIONS AND RELEVANCE

Peripheral pro-inflammatory marker elevations were confirmed in BD. CRP and TNF-α could represent state markers, as they were only elevated during mood episodes, while IL-6 appeared to be a trait marker for BD. Increased variability of specific inflammatory mediators in specific disease active states suggests that a subset of subjects with BD may exhibit elevated inflammation as part of a manic or depressive episode.

A peripheral inflammatory signature discriminates bipolar from unipolar depression: A machine learning approach

BACKGROUND

Mood disorders (major depressive disorder, MDD, and bipolar disorder, BD) are considered leading causes of life-long disability worldwide, where high rates of no response to treatment or relapse and delays in receiving a proper diagnosis (~60% of depressed BD patients are initially misdiagnosed as MDD) contribute to a growing personal and socio-economic burden. The immune system may represent a new target to develop novel diagnostic and therapeutic procedures but reliable biomarkers still need to be found.

METHODS

In our study we predicted the differential diagnosis of mood disorders by considering the plasma levels of 54 cytokines, chemokines and growth factors of 81 BD and 127 MDD depressed patients. Clinical diagnoses were predicted also against 32 healthy controls. Elastic net models, including 5000 non-parametric bootstrapping procedure and inner and outer 10-fold nested cross-validation were performed in order to identify the signatures for the disorders.

RESULTS

Results showed that the immune-inflammatory signature classifies the two disorders with a high accuracy (AUC = 97%), specifically 92% and 86% respectively for MDD and BD. MDD diagnosis was predicted by high levels of markers related to both pro-inflammatory (i.e. IL-1β, IL-6, IL-7, IL-16) and regulatory responses (IL-2, IL-4, and IL-10), whereas BD by high levels of inflammatory markers (CCL3, CCL4, CCL5, CCL11, CCL25, CCL27, CXCL11, IL-9 and TNF-α).

CONCLUSIONS

Our findings provide novel tools for early diagnosis of BD, strengthening the impact of biomarkers research into clinical practice, and new insights for the development of innovative therapeutic strategies for depressive disorders.

Concepts of Neuroinflammation and Their Relationship With Impaired Mitochondrial Functions in Bipolar Disorder

Bipolar disorder (BD) is a chronic psychiatric disease, characterized by frequent behavioral episodes of depression and mania, and neurologically by dysregulated neurotransmission, neuroplasticity, growth factor signaling, and metabolism, as well as oxidative stress, and neuronal apoptosis, contributing to chronic neuroinflammation. These abnormalities result from complex interactions between multiple susceptibility genes and environmental factors such as stress. The neurocellular abnormalities of BD can result in gross morphological changes, such as reduced prefrontal and hippocampal volume, and circuit reorganization resulting in cognitive and emotional deficits. The term "neuroprogression" is used to denote the progressive changes from early to late stages, as BD severity and loss of treatment response correlate with the number of past episodes. In addition to circuit and cellular abnormalities, BD is associated with dysfunctional mitochondria, leading to severe metabolic disruption in high energy-demanding neurons and glia. Indeed, mitochondrial dysfunction involving electron transport chain (ETC) disruption is considered the primary cause of chronic oxidative stress in BD. The ensuing damage to membrane lipids, proteins, and DNA further perpetuates oxidative stress and neuroinflammation, creating a perpetuating pathogenic cycle. A deeper understanding of BD pathophysiology and identification of associated biomarkers of neuroinflammation are needed to facilitate early diagnosis and treatment of this debilitating disorder.

Inflammation Biomarkers in Psychiatry

Introduction:

There has long been a need for diagnostic, theragnostic, and prognostic biomarkers for psychiatric disorders. Biomarkers help in reducing ambiguity and arbitrariness and increase objectivity. In this context, many candidates for hormonal, immunological, serological, and neuroimaging markers have been proposed, but none of these marker candidates alone nor a biomarker panel has been approved for any disease. The fact that almost all psychiatric disorders are heterogeneous makes this process challenging. However, strong biomarker candidates have been identified, especially in light of the large number of clinical and preclinical studies conducted within the last five years.

Objective:

The aim of this article was to compile and discuss the current information on immune biomarkers in major psychiatric disorders, such as schizophrenia, depression, bipolar disorder, and anxiety disorders.

Methods:

In this study, respected scientific databases were searched using key terms related to the subject, and the related literature was examined in detail.

Results:

There are many relationships between psychiatric disorders and immune system parameters. Evidence also suggests that neuroinflammation is involved in the etiopathogenesis of psychiatric disorders. Markers, such as proinflammatory cytokines, tumor necrosis factor alpha, and C-reactive protein have been associated with psychiatric disorders in numerous studies.

Conclusions:

The neuroinflammation hypothesis has an important place in the etiopathogenesis of psychiatric disorders. Uncertainty remains as to whether neuroinflammation is a cause or consequence of psychiatric disorders. Some researchers have indicated that intestinal microbiota composition disorders and dysbiosis are sources of neuroinflammation. Immune marker studies are of great importance in terms of eliminating this uncertainty and overcoming diagnostic and treatment difficulties in the clinic. In this review, biomarker studies on psychiatric disorders were examined from the viewpoint of the immune system and discussed in light of the current studies.

TNF-α and its soluble receptors mediate the relationship between prior severe mood episodes and cognitive dysfunction in euthymic bipolar disorder

BACKGROUND

Bipolar disorder (BD) is one of the most disabling mental health conditions in the world. Symptoms of cognitive impairment in BD contribute directly to occupational and social deficiencies and are very difficult to treat. Converging evidence suggests that BD patients have increased peripheral markers of inflammation. The hypothesis of neuroprogression in BD postulates that cognitive deficits develop over the course of the illness and are influenced by prior severe mood episodes, leading to wear-and-tear on the brain- however, there exists a paucity of data statistically testing a mediating role of immune molecules in cognitive dysfunction in BD.

METHODS

This is a cross-sectional study. We measured serum levels of tumor necrosis factor alpha (TNF-α), and soluble (s) TNF receptors one and two (sTNF-R1 and sTNF-R2) in 219 euthymic BD patients and 52 Healthy Controls (HCs). Structural equation modeling (SEM) was used for the primary purpose of assessing whether TNF markers (measured by the multiple indicators TNF-α, sTNF-R1 and sTNF-R2) mediate the effect or number of prior severe mood episodes (number of prior psychiatric hospitalizations) on cognitive performance.

RESULTS

BD and HC groups did not differ on circulating levels of TNF molecules in the present study. However, we found higher sTNF-R1 concentration in 'late-stage' BD illness (>1 prior psychiatric hospitalization) compared to those in early stage illness. In the subsequent SEM, we found that the model fits the data acceptably (Chi-square = 49.2, p = 0.3), and had a 'close fit' (RMSEA = 0.02, PCLOSE = 0.9). Holding covariates constant (age, sex, premorbid IQ, education, and race), we found that the standardized indirect effect was significant, p = 0.015, 90%CI [-0.07, -0.01], indicating that the estimated model was consistent with peripheral TNF markers partially mediating a causal effect of severe mood episodes on executive function.

CONCLUSIONS

Our results indicate that circulating levels of TNF molecules partially mediate the relationship between prior severe mood episodes and executive function in BD. These results may implicate TNF variables in the neuroprogressive course of BD and could point to novel interventions for cognition.

Role of gut microbiota in the GBR12909 model of mania-like behavior in mice

Growing evidence suggests a role for brain-gut-microbiota axis in affective disorders including major depression and bipolar disorder (BD). Herein, we aim to explore, by employing germ-free (GF) mice, the effect of the indigenous microbiota in the development of mania-like behavior. Conventional and GF mice were evaluated for the hyperlocomotion induced by the dopamine transporter inhibitor GBR12909 (15 mg/Kg), a validated model for mania-like behavior. Inflammatory mediators and neurotrophic factors were quantified in the prefrontal cortex, hippocampus and striatum. Mice lacking indigenous microbiota were less susceptible to the mania-like behavior induced by GBR12909. This effect was associated with decreased levels of inflammatory cytokines such as IL-6 and TNF-α, along with increased concentrations of anti- inflammatory cytokines (IL-10) and of neurotrophins (BDNF and NGF). We provided the first evidence that gut-microbiota-brain axis participates in the development of mania-like behavior in rodents, possibly through neuroimmunepathways.

Increased inflammatory biomarkers and changes in biological rhythms in bipolar disorder: A case-control study

BACKGROUND

Bipolar Disorder (BD) is a chronic psychiatric disorder characterized by mood disturbances that include depressive, manic, and hypomanic episodes. Despite the severity of the symptoms, there is still a gap in the literature on the precise neurobiology and treatment of BD. The investigations of inflammatory changes in BD has increased in the last decade, evincing the importance of its role in the pathophysiology of the disorder. The present study aimed to investigate the inflammatory role in BD, through the evaluation of biomarkers and their relation to biological rhythms.

METHODS

It was conducted a case-control study that included 36 BD and 46 healthy controls (HC). The Cyclooxygenase 2 (COX-2) enzyme, Arachidonic Acid (AA), interleukins (IL) IL-4, IL-5, IL-6, IL-10, IL-33, and Tumor Necrosis Factor Alpha (TNF-α) in the serum of individuals. It also was administered the Biological Rhythm Interview of Assessment in Neuropsychiatry (BRIAN) to the BD and healthy control groups.

RESULTS

The results indicated that the individuals with BD showed increased COX-2, AA, IL-6, and TNF-α levels in comparison to the HC without psychiatric disorders, as well as significant commitments in all domains evaluated by BRIAN.

LIMITATIONS

Uncontrolled pharmacotherapy used by the included bipolar participants, which had important effects on participants' inflammatory systems and the lack of cases with bipolar manic episodes.

CONCLUSIONS

The results of the present study reaffirm that inflammation has an important role in BD, as well as the significant changes in biological rhythms. It is still necessary to better characterize the inflammatory pathway of AA.

Hidradenitis Suppurativa and Bipolar Disorders: A Population-Based Study

BACKGROUND

Psychological comorbidities have been reported in patients with hidradenitis suppurativa (HS), yet only a few studies have investigated the possible association between HS and severe psychiatric disorders. The current study aimed to assess the association between HS and bipolar disorder, a major, chronic, psychiatric disease.

METHODS

A nationwide, population-based study was performed utilizing data from the Clalit Health Services (CHS) database in Israel. The study included 4,191 HS patients and 20,941 age- and gender-matched controls. A multivariate binary logistic regression, adjusted for demographic and behavioral risk factors, was performed.

RESULTS

A higher proportion of bipolar disorders was found among HS patients compared to controls (0.7 vs. 0.1%, respectively). There was an increased proportion of active smokers among HS patients than among controls (53.4 vs. 13.5%, respectively). In the multivariate analysis, adjusting for age, sex, and smoking, HS was found to be independently and positively associated with bipolar disorders (OR 2.12, 95% CI 1.21-3.27, p < 0.01), yet after controlling for body mass this association became nonsignificant.

CONCLUSIONS

Bipolar disorders are associated with HS. Future studies should explore whether cardiometabolic deficiencies might account for this association. Healthcare providers should consider this potential co-occurrence as it may impede patient compliance and require appropriate screening and treatment. Results also stress the need for a multidisciplinary approach to optimize management of the disease and its associated comorbidities.

Neuroinflammation in Bipolar Depression

Bipolar disorder (BD) is a leading cause of worldwide disability among mood disorders. Pathological mechanisms are still vastly unclear, and current treatments with conventional medications are often unsatisfactory in maintaining symptoms control and an adequate quality of life. Consequently, current research is focusing on shedding new light on disease pathogenesis, to improve therapeutic effectiveness. Recent evidence has suggested a prominent role of inflammation in mood disorders. Elevated levels of peripheral proinflammatory mediators have been reported in BD, as well as in other mood disorders, and people with systemic autoimmune diseases have an increased risk of developing BD. These immunological alterations are stable, and current medications are unable to alter peripheral concentrations even when clinical improvement is evident. These findings have also been replicated in the central nervous system (CNS) milieu, whereas genetic studies have shown that these immune alterations are not due to the disorder itself, being detectable before the illness onset. Moreover, these inflammatory modifications seem to be affected by and linked to other biomarkers of the disorder, such as alterations of white matter (WM) microstructure, metabolism, kynurenine pathway, and circadian rhythmicity. Finally, these immune variations seem to be useful as predictors of therapeutic responsiveness to medications, and in discriminating between clinically different outcomes. The objective of this review is to summarize available evidence on the connection between inflammation and BD, focusing on peripheral inflammatory markers and recent findings on their connection with other typical features of BD, to outline a general overview of the disorder. Moreover, it is meant to analyze the issues with data gathering and interpretation, given the partially contradictory and inconsistent nature of results.

Changes in inflammation with treatment for bipolar II depression: Pilot trial data on differential effects of psychotherapy and medication

OBJECTIVES

Limited prospective data, mostly focused on bipolar I disorder, suggests that pro-inflammatory cytokines are elevated in abnormal mood states. We evaluated whether treatment normalizes peripheral markers of inflammation in bipolar II disorder.

METHODS

Using data from a randomized clinical trial of Interpersonal and Social Rhythm Therapy (IPSRT) + quetiapine vs. IPSRT + placebo for bipolar II depression, we examined whether these treatments for bipolar II depression impact inflammatory cytokines and whether observed changes in cytokines are associated with changes in depressive symptomatology as measured by the Hamilton Rating Scale for Depression (HRSD-17).

RESULTS

Cytokine values were available for 33 participants who completed baseline and 20-week followup visits. After excluding those with CRP values >=10 mg/L, there were 27 patients available for analysis (IPSRT+quetiapine N=10, IPSRT+placebo N=17). Baseline measure of inflammation did not appear to moderate treatment response, nor was change in HRSD-17 score correlated with changes in cytokines. Those who received IPSRT+quetiapine had significantly greater increases in IL-6 (p=0.02) and TNF-α (p=0.04), even after adjusting for changes in body mass index, than the IPSRT alone group. Descriptively, the quetiapine group showed increases in pro-inflammatory and decreases in anti-inflammatory cytokines and the psychotherapy group showed reduced pro-inflammatory cytokines.

CONCLUSIONS

Despite both groups showing depression improvement, this small study suggests a more pro-inflammatory cytokine profile over time with quetiapine plus psychotherapy compared to psychotherapy alone. Elevated risk of cardiovascular morbidity and mortality among those with bipolar II disorder underscores the importance of delivering treatments that do not exacerbate these risk factors.

sVCAM-1, sICAM-1, TNF-α and IL-6 levels in bipolar disorder type I: Acute, longitudinal and therapeutic implications

OBJECTIVES

To explore the serum levels of soluble vascular cell adhesion molecule-1 (sVCAM-1), soluble intercellular cell adhesion molecule-1 (sICAM-1), tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in patients with bipolar disorder (BD), with regard to acute episode characteristics, course of the disorder and treatment.

METHODS

The study group consisted of 83 patients diagnosed with BD type I. The control group consisted of 73 healthy individuals, matched with the study group according to age, gender and body mass index. The serum levels of sVCAM-1, sICAM-1, TNF-α and IL-6 were measured by ELISA.

RESULTS

Compared with healthy controls, significantly elevated levels of IL-6 and sICAM-1 and significantly lower levels of TNF-α and sVCAM-1 were identified in acute and remission phases of BD. The acute serum levels of sVCAM-1 were associated with the type and severity of acute mood symptoms as well as with course of illness characteristics. TNF-α was associated with duration of untreated disorder and type of treatment.

CONCLUSIONS

BD is related to both acute and long-term alterations of immune mediators, including adhesion molecules. The potential immunomodulatory role of pharmacotherapeutic treatment is also to be considered in BD.

Peripheral blood lymphocyte subpopulations in patients with bipolar disorder type II

We investigated the phenotype of peripheral blood lymphocytes of patients with bipolar disorder type II in different phases of the disease in order to check whether there are specific changes in the immune parameters. Lymphocytes subpopulations were analyzed ex vivo with flow cytometry in patients in euthymic, depression or hypomanic phase of the disease and compared with healthy controls. All BD patients were characterized by lower percentage of CD3⁺CD4⁺ and CD3⁺CD8⁺ cells compared with healthy people. But only patients in depression and remission had higher percentage of B cells (CD19⁺ cells) compared with healthy people. The percentage of CD4⁺CD25⁺ and CD8⁺CD25⁺ cells was decreased in patients in hypomanic phase compared with healthy control. Patients in remission were characterized by increased concentrations of IL-6 and IL-10 and decreased level of TNF in blood serum. Significant correlations between immunologic parameters and the results of Hamilton or Young scale have also been found. Our results demonstrate that there are significant differences in lymphocyte subpopulations which depend on the phase of the disease the patient is currently in.

The association between low-grade inflammation and the clinical features of bipolar disorder in Han Chinese population

Variety of evidence suggests that low-grade inflammation may be involved in the pathophysiology of bipolar disorder (BD). However, the conclusion regarding the relationship between inflammation and BD has been inconsistent. In this study, we aimed to survey the prevalence of low-grade inflammation in a large Han Chinese population with BD and assess its impact on the clinical features of BD. 430 eligible cases were drawn from patients who were admitted or had ever been admitted for BD to the inpatient service of the psychiatric department of the Third Hospital of Sun Yat-sen University. Subjects with current active physical diseases or white blood count (WBC) >19.0 × 10⁹/L (2 times the upper reference) were excluded. Serum C-reactive protein (CRP) levels and WBC were measured with fast blood sample. Low-grade inflammation was defined as CRP>3 mg/L or WBC > 9.5 × 10⁹/L(the upper reference). Clinical features of BD were collected through semi-structural interview conducted by trained interviewers with background of psychiatric education. If defined as CRP>3 mg/L, the prevalence of low-grade inflammation among BD was 10.1% (41/404), it was positively associated with BMI (p = 0.012), comorbidity of glycolipid metabolic diseases(p = 0.018). After adjusting for BMI, it was found to be positively related to recent suicide attempt (p = 0.03), initiation with (hypo)manic episode(p = 0.047), leaden paralysis (p = 0.037) and family history of mental disorders(p = 0.012), while the association between comorbidity of glycolipid metabolic diseases and low-grade inflammation disappeared (p = 0.330). If defined as WBC > 9.5 × 10⁹/L, the prevalence of low-grade inflammation was 8.1% (33/409), it was positively associated with psychotic features (p = 0.011) and adverse life events before the onset of illness(p < 0.001), but was not significantly influenced by BMI (p = 0.077). A much lower prevalence of low-grade inflammation in BD is found among Han Chinese population than among western population. Low-grade inflammation of different definition impacts differentially on the clinical features of BD.

Neurotrophins, cytokines, oxidative stress mediators and mood state in bipolar disorder: systematic review and meta-analyses

BACKGROUND

A reliable biomarker signature for bipolar disorder sensitive to illness phase would be of considerable clinical benefit. Among circulating blood-derived markers there has been a significant amount of research into inflammatory markers, neurotrophins and oxidative stress markers.AimsTo synthesise and interpret existing evidence of inflammatory markers, neurotrophins and oxidative stress markers in bipolar disorder focusing on the mood phase of illness.

METHOD

Following PRISMA (Preferred Reporting Items for Systematic reviews and Meta-analyses) guidelines, a systematic review was conducted for studies investigating peripheral biomarkers in bipolar disorder compared with healthy controls. We searched Medline, Embase, PsycINFO, SciELO and Web of Science, and separated studies by bipolar mood phase (mania, depression and euthymia). Extracted data on each biomarker in separate mood phases were synthesised using random-effects model meta-analyses.

RESULTS

In total, 53 studies were included, comprising 2467 cases and 2360 controls. Fourteen biomarkers were identified from meta-analyses of three or more studies. No biomarker differentiated mood phase in bipolar disorder individually. Biomarker meta-analyses suggest a combination of high-sensitivity C-reactive protein/interleukin-6, brain derived neurotrophic factor/tumour necrosis factor (TNF)-α and soluble TNF-α receptor 1 can differentiate specific mood phase in bipolar disorder. Several other biomarkers of interest were identified.

CONCLUSIONS

Combining biomarker results could differentiate individuals with bipolar disorder from healthy controls and indicate a specific mood-phase signature. Future research should seek to test these combinations of biomarkers in longitudinal studies.Declaration of interestNone.

Cytokine, chemokine and BDNF levels in medication-free pediatric patients with obsessive-compulsive disorder

The aim of this study was to investigate whether the serum levels of IL-12, IL-17, TGFβ, TNF-alpha, sTNFR1, sTNFR2, IL-1β, CCL3, CCL24, CXCL8, and BDNF are associated with obsessive-compulsive disorder (OCD) in medication-free children. A total of 44 (22 boys/22 girls) medication-free children with OCD and 40 (23 boys/17 girls) healthy controls were included in this study. The severity of the OCD symptoms were assessed by the Children's Yale-Brown Obsessive-Compulsive Scale and the Maudsley Obsessive-Compulsive Inventory. The Children's Depression Inventory and the Screen for Child Anxiety-Related Emotional Disorders were applied to the children in order to determine depression and anxiety levels. IL-17, IL-12, TGF β, TNF-alpha, sTNFR1, sTNFR2, IL-1β, CCL3, CCL24, CXCL8, and BDNF levels were measured by enzyme-linked immunosorbent assay. Multivariate analysis of covariance (MANCOVA) revealed a significant main effect on both groups for the levels of serum cytokine, chemokine, and BDNF, an effect that was independent of severities of depression and anxiety [Pillai's Trace V = 0.371, F (11, 70) = 3.756, p < 0.001, hp² = 0.187]. Analysis of covariance (ANCOVA) indicated that serum TNF-alpha levels were significantly higher in the OCD group than in the control group (p < 0.001). In contrast, serum IL-12 levels were significantly lower in the OCD group than in the control group (p = 0.014). These findings suggest that TNF-alpha and IL-12 may play a role in the pathophysiology of OCD in children. The causal relationship between these proinflammatory cytokines and pediatric OCD requires further investigation.

Are there differences in lipid peroxidation and immune biomarkers between major depression and bipolar disorder: Effects of melancholia, atypical depression, severity of illness, episode number, suicidal ideation and prior suicide attempts

BACKGROUND

There is evidence that major depression (MDD) and bipolar disorder (BD) are accompanied by activated immune & oxidative (I&O) pathways.

METHODS

To compare I&O biomarkers between MDD and BD we assessed serum levels of thiobarbituric acid reactive substances (TBARS; a lipid peroxidation marker), soluble interleukin-2 receptor (sIL-2R), sIL-6R, IL-α, sIL-1R antagonist (sIL-1RA), tumor necrosis factor receptor 60kDa/80kDa (sTNFR60/R80) in 114 MDD and 133 BD patients, and 50 healthy controls. We computed z-unit weighted indices reflecting the 5 cytokine receptor levels (zCytR), cell-mediated immunity (zCMI) and I&O pathways (zCMI+TBARS).

RESULTS

There are no significant differences in biomarkers between MDD and BD. BD/MDD with atypical features is characterized by increased sIL-6R and TBARS, whereas melancholia is associated with higher TBARS and lower sTNFR60 levels. Severity of illness, as measured with the Hamilton Depression Rating Scale, is correlated with increased sIL-6R, sTNFR80, TBARS, zCytR and zCMI+TBARS. The number of episodes the year prior to blood sampling is positively associated with sTNFR80, TBARS, zCMI, zCMI+TBARS, while number of hospitalizations is positively associated with sIL-1RA. Prior suicidal attempts are associated with increased sIL-1RA, IL-1α, zCMI, TBARS and zCMI+TBARS, while TBARS is associated with current suicidal ideation.

CONCLUSIONS

There are no I&O biomarker differences between MDD and BD. Atypical depression is associated with increased IL-6 trans-signaling and lipid peroxidation. Severity of depression, number of episodes and suicidal attempts are associated with activated I&O pathways. Increased TBARS is the single best predictor of BD/MDD, atypical depression, melancholia and current suicidal ideation.

Proinflammatory Cytokines, Mood, and Sleep in Interepisode Bipolar Disorder and Insomnia: A Pilot Study With Implications for Psychosocial Interventions

OBJECTIVE

Proinflammatory cytokines are associated with bipolar disorder (BD), but less is known about how cytokines function during the interepisode period. This study examined cytokines, mood symptoms, and sleep in individuals with interepisode BD with complaints of insomnia. We also investigated the effects of a BD-specific modification of cognitive behavior therapy for insomnia (CBTI-BP) on cytokine levels.

METHODS

Twenty-two adults with interepisode BD type I and insomnia were drawn from a subset of a National Institute of Mental Health funded study. Participants were randomly allocated to CBTI-BP (n = 11) or psychoeducation (n = 11). Participants completed a sleep diary, rated self-report measures of mania and depression, and provided samples assayed for interleukin (IL)-6 and tumor necrosis factor soluble receptor 2 (sTNF-R2).

RESULTS

IL-6 was associated with mania symptoms (rs = 0.44, p = .041) and total sleep time (rs = -0.49, p = .026). IL-6 was related to depression symptoms at the trend level (rs = 0.43, p = .052). sTNF-R2 was not significantly related to mood or sleep measures. From pretreatment to posttreatment, CBTI-BP compared with psychoeducation was associated with a nonsignificant, large effect size decrease in IL-6 (z = -1.61, p = .13, d = -0.78) and a nonsignificant, small-medium effect size decrease in sTNF-R2 (z = -0.79, p = .44, d = -0.38).

CONCLUSIONS

These findings provide preliminary evidence that IL-6 is related to mania symptoms and shorter total sleep time in interepisode BD. A treatment that targets sleep in BD could potentially decrease IL-6 although replication is warranted.

Circulating cathelicidin LL-37 level is increased in euthymic patients with bipolar disorder

More and more data seems to imply that immune mechanisms are involved in the pathomechanism of bipolar disorder (BD). However, the primary role of cathelicidin LL-37 is defense against pathogens, more and more data indicated that this peptide strongly modulates immune system functioning and contributes to immune pathology of chronic and inflammatory diseases. No data is available on the level of LL-37 in bipolar patients. The aim of the study was to examine the circulating levels of cathelicidin LL-37 in euthymic patients with BD. Forty patients with BD and fifty-nine healthy volunteers were enrolled into the study. Concentration of LL-37 in serum was assessed using immunoenzymatic test ELISA. The mean LL-37 concentration in bipolar patients and in healthy subjects were 4.60 ± 7.65 ng/mL and 1.92 ± 2.89 ng/mL, respectively, and the difference was statistically significant (p = 0.035). Within the BD group LL-37 level was significantly higher in women than in men (p = 0.045). The evaluation of serum LL-37 concentration during stable 8 week treatment indicated that at baseline (T1) mean level of LL-37 was 5.82 ± 10.59 ng/mL; and after treatment (T2) was 4.33 ± 5.87 ng/mL; the difference between T1 and T2 was not significant. Elevated serum levels of LL-37 in bipolar patients may suggest the role of this peptide in the pathomechanism of BD.

Lipid Peroxidation and Immune Biomarkers Are Associated with Major Depression and Its Phenotypes, Including Treatment-Resistant Depression and Melancholia

To examine immune-inflammatory and oxidative (I&O) biomarkers in major depression (MDD) and its related phenotypes, we recruited 114 well-phenotyped depressed patients and 50 healthy controls and measured serum levels of interleukin (IL)-1α, soluble IL-1 receptor antagonist (sIL-1RA), soluble IL-2 receptor (sIL-2R), soluble IL-6 receptor (sIL-6R), soluble tumor necrosis factor receptor 60 and 80 kDa (sTNF-R1/R2), and thiobarbituric acid reactive substances (TBARS). Obtained results indicate that MDD is characterized by increased sIL-1RA, sTNF-R1, and TBARS concentrations. Melancholic depression is associated with increased sIL-6R but lowered IL-1α levels. A current episode of depression is accompanied by significantly increased sIL-6R compared to the remitted state. Treatment-resistant depression (TRD) is accompanied by increased sIL-6R and TBARS but lowered sTNF-R2 levels compared to non-TRD patients. These immune markers are not significantly correlated with Hamilton Depression Rating Scale (HDRS), Montgomery-Asberg Depression Scale (MADRS), number episodes, or age at onset. Our findings show that increased sIL-1RA, sTNF-R1, and TBARS levels may be trait markers of depression, while increased sIL-6R levels may be a state marker of melancholia and an acute phase of depression. MDD is accompanied by increased lipid peroxidation and simultaneous activation of immune pathways, and the compensatory anti-inflammatory reflex system (CIRS). TRD is characterized by highly increased oxidative stress and probably increased TNFα and IL-6 trans-signalling. Novel treatments for major depression should target oxidative stress pathways, while new treatments for TRD should primary target lipid peroxidation and also activated immune-inflammatory pathways.

Serum TNF-related weak inducer of apoptosis (TWEAK) and TNF-related apoptosis-inducing ligand (TRAIL) levels of patients with bipolar disorder in manic episode, in remission and healthy controls

TNF-related weak inducer of apoptosis (TWEAK) and TNF-related apoptosis-inducing ligand (TRAIL) are members of TNF superfamily, which has various roles in immunologic and inflammatory reactions in the organism. Pathophysiology in bipolar disorder is still under investigation and altered serum levels of cytokines are often encountered. Aim of this study is to detect serum TWEAK and TRAIL levels of patients with bipolar disorder and healthy controls. For this purpose, 55 patients with bipolar disorder -27 manic episode (ME), 28 remission (RE) and 29 healthy controls (HC) were included. TWEAK levels of ME and RE groups were significantly lower than HC. TWEAK levels of bipolar patients (BP) were also lower than HC. TRAIL levels of ME, RE, HC groups and BP, HC groups were statistically similar. In our knowledge, this is the first study concerning about TWEAK and TRAIL levels in bipolar disorder and our results pointed that TWEAK-related immune response might be impaired in bipolar disorder, but our study fails to eradicate the confounders such as medication, smoking and body mass index. Studies having larger samples and limited confounders are needed to be able to evaluate these changes better and detect possible alterations about TRAIL and other TNF superfamily members.

A systematic review of evidence for the role of inflammatory biomarkers in bipolar patients

Bipolar disorder (BD) is a neuropsychiatric disorder that is characterized by a phasic course of affective episodes interspersed with a euthymic state. Epidemiological, clinical, genetic, post-mortem and preclinical studies have shown that inflammatory reactions and immune modulation play a pivotal role in the pathophysiology of BD. It is conceptualized that biomarkers of inflammation and immune responses should be employed to monitor the disease process in bipolar patients. The objective of this systematic review is to analyse the inflammatory markers involved in human studies and to explore each individual marker for its potential clinical application and summarize evidence regarding their role in BD. A systematic review of human studies to measure inflammatory markers was conducted, and the studies were identified by searching PubMed/MEDLINE, PsycINFO, EMBASE, and Web of Science databases for peer-reviewed journals that were published until September 2015. In this review, we included peripheral markers, genetic, post-mortem and cell studies with inflammatory biomarker analysis in BD. One hundred and two (102) papers met the inclusion criteria. The pro-inflammatory cytokines were elevated and the anti-inflammatory cytokines were reduced in BD patients, particularly during manic and depressive phases when compared to the controls. These changes tend to disappear in euthymia, indicating that inflammation may be associated with acute phases of BD. Even though there are promising findings in this field, further clinical studies using more established detection techniques are needed to clearly show the benefit of using inflammatory markers in the diagnosis, follow-up and prognosis of patients with BD.

Plasma Levels of Tumor Necrosis Factor Superfamily Molecules Are Increased in Bipolar Disorder

Objective

Patients with bipolar disorder (BD) exhibit peripheral low-grade inflammation. The aim of the current study was to investigate the involvement of hitherto unexplored components of the tumor necrosis factor (TNF) superfamily in BD.

Methods

Eighty patients with type I BD and 50 healthy controls matched for age and gender were enrolled in this study. All subjects were assessed with the Mini-Plus to evaluate psychiatric comorbidities; the Young Mania Rating Scale and the Hamilton Depression Rating Scale to evaluate manic and depressive symptoms severity, respectively. TNF superfamily molecules (TNF, TNF-related weak inducer of apoptosis [TWEAK], TNF-related apoptosis-inducing ligand [TRAIL], soluble TNF receptor type 1 [sTNFR1], and soluble TNF receptor type 2 [sTNFR2]) levels were measured by ELISA.

Results

Patients with BD, regardless of mood state, presented increased plasma levels of sTNFR1 and TWEAK in comparison with controls.

Conclusion

These findings corroborate the view that TNF superfamily may play a role in BD pathophysiology.

Clinical staging and serum cytokines in bipolar patients during euthymia

AIMS

Changes in serum cytokines and altered neutrophin concentration have been associated with bipolar disorder (BD). Our aim here was to analyze peripheral blood biomarkers according to the clinical stages of BD.

METHOD

Euthymic BD-I patients were grouped according to their level of functioning in early-stage (n=25) and late-stage (n=23), and compared to healthy siblings (n=23) and genetically unrelated healthy controls (n=21). Neurotrophin (neurotrophin-3 and BDNF) concentration and biomarkers of inflammation, including cytokines (IL-6, IL-10 and TNF-α), leukocytes count and acute phase proteins, were measured.

RESULTS

IL-10 concentration was significantly increased in early-stage patients compared to late-stage patients, healthy siblings and controls whereas TNF-α concentration was significantly increased in late-stage patients compared to controls. Total leukocytes, neutrophil and monocyte count were significantly increased in late-stage patients compared to healthy siblings and controls. The concentration of IL-6, neurotrophin-3 and BDNF was unchanged in euthymia. Healthy siblings did not show significant changes in any biomarker.

CONCLUSIONS

The concentration of IL-10, TNF-α, neutrophil and monocytes subtype count in blood is altered in patients with BD during euthymic state. The link between peripheral inflammation and different stages in BD deserves further studies.

Biological hypotheses and biomarkers of bipolar disorder

The most common mood disorders are major depressive disorders and bipolar disorders (BD). The pathophysiology of BD is complex, multifactorial, and not fully understood. Creation of new hypotheses in the field gives impetus for studies and for finding new biomarkers for BD. Conversely, new biomarkers facilitate not only diagnosis of a disorder and monitoring of biological effects of treatment, but also formulation of new hypotheses about the causes and pathophysiology of the BD. BD is characterized by multiple associations between disturbed brain development, neuroplasticity, and chronobiology, caused by: genetic and environmental factors; defects in apoptotic, immune-inflammatory, neurotransmitter, neurotrophin, and calcium-signaling pathways; oxidative and nitrosative stress; cellular bioenergetics; and membrane or vesicular transport. Current biological hypotheses of BD are summarized, including related pathophysiological processes and key biomarkers, which have been associated with changes in genetics, systems of neurotransmitter and neurotrophic factors, neuroinflammation, autoimmunity, cytokines, stress axis activity, chronobiology, oxidative stress, and mitochondrial dysfunctions. Here we also discuss the therapeutic hypotheses and mechanisms of the switch between depressive and manic state.

Bipolar disorder moderates associations between linoleic acid and markers of inflammation

Dietary polyunsaturated fatty acids (PUFA) and inflammatory proteins associate with immune activation and have been implicated in the pathophysiology of mood disorders. We have previously reported that individuals with bipolar disorder (BPD) have decreased PUFA intake, including eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and arachidonic acid (AA); and decreased PUFA concentration of plasma EPA and linoleic acid (LA). We have also reported an association between plasma LA and its metabolites and burden of disease measures in BPD. In the current cross-sectional study we collected blood samples and diet records from both bipolar (n = 91) and control subjects (n = 75) to quantify plasma cytokine concentrations and dietary LA intake, respectively. Using multiple linear regression techniques, we tested for case control differences in plasma cytokine levels and associations between cytokines and dietary LA intake, adjusting for sex, age, BMI, and total energy intake. We found significantly higher plasma levels of interleukin 18 (IL-18) (p = 0.036), IL-18 binding protein (IL-18BP) (p = 0.001), soluble tumor necrosis factor receptor (sTNFR) 1 (p = 0.006), and sTNFR2 (p = 0.007) in BPD compared with controls. Moreover, BPD significantly moderated the associations of dietary LA intake with plasma levels of IL-18, sTNFR1 and sTNFR2, which were inverse associations in bipolar individuals and positive associations in controls (p for dietary LA x BPD diagnosis interaction < 0.05 for all three). These findings suggest potential dysregulation of LA metabolism in BPD, which may extend to a modified influence of dietary LA on specific inflammatory pathways in individuals with BPD compared to healthy controls.

Metabolic syndrome and adverse clinical outcomes in patients with bipolar disorder

BACKGROUND

Metabolic syndrome (MetS) is highly prevalent among patients with bipolar disorder. MetS may cause complications in the brain, but studies investigating MetS-associated clinical psychiatric outcomes remain scant.

METHODS

We enrolled clinically stable outpatients with bipolar disorder aged 18-65 years and performed anthropometric and fasting biochemical assessments to investigate MetS prevalence. We then performed clinical assessments by using the Young Mania Rating Scale for manic symptoms, the Montgomery-Åsberg Depression Rating Scale for depressive symptoms, the Positive and Negative Symptom Scale for psychotic symptoms, the Involuntary Movement Scale for tardive dyskinesia, the Barnes Akathisia Rating Scale for akathisia, the Udvalg for Kliniske Undersogelser for general side effects, the Schedule for Assessment of Insight for insight, the Global Assessment of Functioning scale for global functioning, and the Wisconsin Card Sorting Test (WCST) for cognitive executive function.

RESULTS

In total, 143 patients were enrolled and had a MetS prevalence of 29.4%. The patients treated with atypical antipsychotics plus mood stabilizers (36.3%) and atypical antipsychotics alone (36.0%) had a significantly higher prevalence of MetS than did those treated with mood stabilizers alone (10.5%; p = 0.012). According to multivariate regression analyses adjusted for age, sex, smoking status, bipolar disorder subtype (I or II), pharmacological treatment duration, and psychiatric medication, compared with patients without MetS, those with MetS had significantly more previous hospitalizations (p = 0.036), severer tardive dyskinesia (p = 0.030), poorer insight (p = 0.036), poorer global function (p = 0.046), and more impaired executive function (conceptual level response on the WCST; p = 0.042).

CONCLUSIONS

Our results indicated that patients with comorbid bipolar disorder and MetS have more adverse clinical outcomes than those without, with more hospitalizations, severer tardive dyskinesia, poorer insight, poorer global function, and more impaired executive function. Monitoring MetS is crucial for assessing not only physical burden, but also psychiatric outcomes.

Effect of Increased Neutrophil-to-Lymphocyte Ratio (NLR) and Decreased Mean Platelet Volume (MPV) Values on Inflammation in Acute Mania

INTRODUCTION

The neutrophil-to-lymphocyte ratio (NLR) and mean platelet volume (MPV) are simple, low-cost, and useful inflammatory markers detected in routine complete blood count (CBC), and their use has recently become widespread. In this study, we aimed to investigate the presence of an inflammatory state in manic patients on the basis of NLR and MPV values.

METHODS

This retrospective study was performed on 76 patients with acute mania who were admitted to the Inpatients Psychiatry Clinic of Afyon Kocatepe University Hospital in Turkey. Diagnoses were based on Diagnostic and Statistical Manuel of Mental disorder (DSM-IV). The control group consisted of 74 healthy individuals recruited from the community. They were age- and sex-matched with the study group.

RESULTS

NLR values of the manic patient group were 2.2±1.4 and those of the control group were 1.6±0.5. NLR values were significantly higher (p=0.004) and MPV values were significantly lower in the manic patient group than in the control group (10.0±1.2 vs. 10.9±2.3, p=0.027).

CONCLUSION

Increased NLR and decreased MPV levels may reflect inflammation in manic patients, and inflammation may play a role in the complex pathophysiology of acute mania.

The effect of mood-stabilizing drugs on cytokine levels in bipolar disorder: A systematic review

OBJECTIVES

Cytokine level alterations suggest a role for the immune system in the pathophysiology of bipolar disorder (BD). Pharmacotherapy is an important confounding factor in clinical research on cytokine levels. In this systematic review we collate the evidence on blood cytokine levels in medication-free BD and the effects of single mood-stabilizing drugs on these levels.

METHODS

A systematic review was conducted according to the PRISMA statement. We searched the Pubmed and Embase databases for clinical studies reporting either on cytokine levels in medication-free BD or on the effects of single mood-stabilizing drugs on cytokine levels in BD.

RESULTS

Of the 564 articles screened, 17 were included. Fourteen articles report on medication-free patients with BD and indicate state-related cytokine alterations. Six articles discuss the effect of lithium. Whereas no data on short-term effects of lithium were found, ≥2 months lithium use in euthymic populations is associated with normal cytokine levels. Two studies report no effect of valproate and no studies were found on carbamazepine, lamotrigine or antipsychotics.

LIMITATIONS

The available studies are characterized by a broad methodological heterogeneity and limited replication between studies.

CONCLUSIONS

This systematic review suggests the presence of state-related cytokine level alterations in medication-free BD with most evidence pointing to a proinflammatory cytokine response in mania. Euthymia and long-term lithium use are associated with normal cytokine levels. To improve our understanding of the impact of mood-stabilizing drugs on cytokine levels, longitudinal studies with medication-free baseline, randomized controlled single-drug treatment protocols and close mood state monitoring are needed.

Mania induced by adalimumab in a patient with ankylosing spondylitis

Objectives Monoclonal antibodies such as antagonists of tumor necrosis factor-alpha have been shown to have beneficial effects on the well-being of patients with inflammatory illnesses. However, mood episodes triggered by such agents have been reported. We herein report the case of mania induced by adalimumab treatment in an adult with ankylosing spondylitis, which later resolved once adalimumab was discontinued and mood stabilizers were initiated. Methods A 25-year-old man, with prior history of dysthymia, was diagnosed with ankylosing spondylitis and started on adalimumab. He gradually developed manic symptoms over seven to eight months, while maintained on adalimumab. As his condition did not improve with outpatient management, the patient was admitted to the Psychiatry inpatient unit. Results Valproate and aripiprazole were initiated, and adalimumab was substituted with non-steroidal anti-inflammatory agents. Mood symptoms resolved within days, and the patient was discharged. Upon follow-up, the patient was euthymic and compliant to his psychotropic medications. He was started on certolizumab, a different immunomodulatory, for his ankylosing spondylitis. Conclusions Immunological modulation might be a key factor in triggering, maintaining, or treating mood symptoms. Further research in this field is warranted to better understand the pathophysiology of mania. To our knowledge, manic symptoms induced by adalimumab have not been previously reported in the literature, which is why our case report can have an impact in recognizing this important clinical adverse effect.

The role of tumour necrosis factor alpha and soluble tumour necrosis factor alpha receptors in the symptomatology of schizophrenia

Background Immunological mechanisms may be responsible for the development and maintenance of schizophrenia symptoms. Aim The aim of this study is to measure tumour necrosis factor-alpha (TNF-α), soluble tumour necrosis factor-alpha receptor I (sTNF-αRI), and soluble tumour necrosis factor-alpha receptor II (sTNF-αRII) levels in patients with schizophrenia and healthy individuals, and to determine their relationship with the symptoms of schizophrenia. Methods Serum TNF-α, sTNF-αRI and sTNF-αRII levels were measured. The Positive and Negative Syndrome Scale (PANSS) was administered for patients with schizophrenia (n = 35), and the results were compared with healthy controls (n = 30). Hierarchical regression analyses were undertaken to predict the levels of TNF-α, sTNF-αRI and sTNF-αRII. Results No significant difference was observed in TNF-α levels, but sTNF-αRI and sTNF-αRII levels were lower in patients with schizophrenia. Serum sTNF-αRI and sTNF-αRII levels were found to be negatively correlated with the negative subscale score of the PANSS, and sTNF-αRI levels were also negatively correlated with the total score of the PANSS. Smoking, gender, body mass index were not correlated with TNF-α and sTNF-α receptor levels. Conclusions These results suggest that there may be a change in anti-inflammatory response in patients with schizophrenia due to sTNF-αRI and sTNF-αRII levels. The study also supports low levels of TNF activity in schizophrenia patients with negative symptoms.

Leptin is associated with mood status and metabolic homeostasis in patients with bipolar disorder

BACKGROUND

Patients with bipolar disorder are at a high risk for becoming obese. Adipokines are associated with depression and obesity via the inflammatory process. However, few studies have investigated the associations between depression and leptin, adiponectin and resistin levels in patients with bipolar disorder. We explored the associations between serum levels of leptin, adiponectin and resistin and mood and metabolic status in patients with bipolar disorder.

METHODS

Body mass index (BMI) and serum leptin, adiponectin and resistin levels were assessed in 94 Korean patients with bipolar disorder. The Hamilton Rating Scale for Depression-17 and the Young Mania Rating Scale were used to assess mood state.

RESULTS

Leptin (17.19 ± 13.08 vs. 10.47 ± 10.05 ng/ml; p = 0.008) and adiponectin (10.51 ± 8.37 vs. 5.91 ± 2.82 μg/ml; p = 0.001) levels were higher in female than in male patients. After adjusting for mood state, age, smoking, alcohol habit, and BMI in a multivariate analysis of covariance (MANCOVA), leptin (17.86 ± 1.22 vs. 10.05 ± 1.48 ng/ml; p < 0.001) and adiponectin (10.18 ± 0.98 vs. 6.40 ± 1.19 μg/ml; p = 0.027) levels were still higher in female than in male patients. Compared to euthymic patients, depressed patients had higher levels of leptin (17.37 ± 14.69 vs. 11.65 ± 9.04 ng/ml; p = 0.024), but there was no significant difference in adiponectin and resistin levels between the two groups. After adjusting for age, gender and BMI in the MANCOVA, leptin levels were also significantly higher in depressed (16.78 ± 1.34 ng/ml) than in euthymic patients (10.73 ± 1.22 ng/ml; p = 0.001).

CONCLUSION

Leptin is closely associated with the regulation of mood and metabolic homeostasis in patients with bipolar disorder.

Bipolar Disorder: Role of Inflammation and the Development of Disease Biomarkers

Bipolar disorder is a severe and enduring psychiatric condition which in many cases starts during early adulthood and follows a relapsing and remitting course throughout life. In many patients the disease follows a progressive path with brief periods of inter-episode recovery, sub-threshold symptoms, treatment resistance and increasing functional impairment in the biopsychosocial domains. Knowledge about the neurobiology of bipolar disorder is increasing steadily and evidence from several lines of research implicates immuno-inflammatory mechanisms in the brain and periphery in the etiopathogenesis of this illness and its comorbidities. The main findings are an increase in the levels of proinflammatory cytokines during acute episodes with a decrease in neurotrophic support. Related to these factors are glial cell dysfunction, neuro-endocrine abnormalities and neurotransmitter aberrations which together cause plastic changes in the mood regulating areas of the brain and neuroprogression of the bipolar diathesis. Research in the above mentioned areas is providing an opportunity to discover novel biomarkers for the disease and the field is reaching a point where major breakthroughs can be expected in the not too distant future. It is hoped that with new discoveries fresh avenues will be found to better treat an otherwise recalcitrant disease.

Nod-like receptor pyrin containing 3 (NLRP3) in the post-mortem frontal cortex from patients with bipolar disorder: A potential mediator between mitochondria and immune-activation

Mitochondrial complex I dysfunction, oxidative stress and immune-activation are consistently reported in bipolar disorder (BD). Mitochondrial production of reactive oxygen species was recently linked to activation of an inflammatory redox sensor, the nod-like receptor family pyrin domain-containing 3 (NLRP3). Upon its activation, NLRP3 recruits apoptosis-associated speck-like protein (ASC) and caspase-1 to form the NLRP3-inflammasome, activating IL-1β. This study aimed to examine if immune-activation may be a downstream target of complex I dysfunction through the NLRP3-inflammasome in BD. Post-mortem frontal cortex from patients with BD (N = 9), schizophrenia (N = 10), and non-psychiatric controls (N = 9) were donated from the Harvard Brain Tissue Resource Center. Levels of NLRP3, ASC and caspase-1 were measured by western blotting, ELISA and Luminex. While we found no effects of age, sex or post-mortem delay, lower levels of complex I (F2,25 = 3.46, p < 0.05) and NDUFS7, a subunit of complex I (F2,25 = 4.13, p < 0.05), were found in patients with BD. Mitochondrial NLRP3 (F2,25 = 3.86, p < 0.05) and ASC (F2,25 = 4.61, p < 0.05) levels were higher in patients with BD. However, levels of caspase 1 (F2,25 = 4.13, p < 0.05 for both), IL-1β (F2,25 = 7.05, p < 0.01), IL-6 (F2,25 = 5.48, p < 0.05), TNFα (F2,25 = 7.14, p < 0.01) and IL-10 (F2,25 = 5.02, p < 0.05) were increased in both BD and schizophrenia. These findings suggest that immune-activation in the frontal cortex may occur both in patients with BD and schizophrenia, while complex I dysfunction and NLRP3-inflammasome activation may be more specific to BD.

Inflammatory markers among adolescents and young adults with bipolar spectrum disorders

OBJECTIVE

Despite burgeoning literature in middle-aged adults, little is known regarding proinflammatory markers (PIMs) among adolescents and young adults with bipolar disorder. Similarly, few prior studies have considered potential confounds when examining the association between PIMs and bipolar disorder characteristics. We therefore retrospectively examined these topics in the Course and Outcome of Bipolar Youth (COBY) study.

METHOD

Subjects were 123 adolescents and young adults (mean [SD] = 20.4 ± 3.8 years; range, 13.4-28.3 years) in COBY, enrolled between October 2000 and July 2006. DSM-IV diagnoses were determined using the Schedule for Affective Disorders and Schizophrenia for School-Age Children (K-SADS). Clinical characteristics during the preceding 6 months, including mood, comorbidity, and treatment, were evaluated using the Longitudinal Interval Follow-Up Evaluation (LIFE). Serum levels of interleukin (IL)-6, tumor necrosis factor (TNF)-α, and high-sensitivity C-reactive protein (hsCRP) were assayed. Primary analyses examined the association of PIMs with bipolar disorder characteristics during the preceding 6 months.

RESULTS

Several lifetime clinical characteristics were significantly associated with PIMs in multivariable analyses, including longer illness duration (P = .005 for IL-6; P = .0004 for hsCRP), suicide attempts (P = .01 for TNF-α), family history of suicide attempts or completion (P = .01 for hsCRP), self-injurious behavior (P =.005 for TNF-α), substance use disorder (SUD) (P < .0001 for hsCRP), and family history of SUD (P = .02 for TNF-α; P = .01 for IL-6). The following bipolar disorder characteristics during the preceding 6 months remained significantly associated with PIMs in multivariable analyses that controlled for differences in comorbidity and treatment: for TNF-α, percentage of weeks with psychosis (χ(2) = 5.7, P =.02); for IL-6, percentage of weeks with subthreshold mood symptoms (χ(2)= 8.3, P = .004) and any suicide attempt (χ(2) = 6.1, P = .01); for hsCRP, maximum severity of depressive symptoms (χ(2) = 8.3, P =.004).

CONCLUSION

Proinflammatory markers may be relevant to bipolar disorder characteristics as well as other clinical characteristics among adolescents and young adults with bipolar disorder. Traction toward validating PIMs as clinically relevant biomarkers in bipolar disorder will require repeated measures of PIMs and incorporation of relevant covariates.

Abnormal gene expression of proinflammatory cytokines and their receptors in the lymphocytes of patients with bipolar disorder

OBJECTIVES

Abnormalities of protein levels of proinflammatory cytokines and their soluble receptors have been reported in plasma of patients with bipolar disorder (BP). In this study, we tested the hypothesis that the mRNA expression of membrane-bound receptors for proinflammatory cytokines will be altered in the lymphocytes of patients with BP.

METHODS

We determined protein and mRNA expression of proinflammatory cytokines, and mRNA expression of their receptors in the lymphocytes from 29 drug-free, hospitalized patients with BP and 30 drug-free normal control subjects. The subjects were diagnosed according to DSM-IV criteria. Plasma protein levels of cytokines were determined by enzyme-linked immunosorbent assay (ELISA); mRNA levels in lymphocytes were determined by the quantitative polymerase chain reaction (qPCR) method.

RESULTS

We found that mean mRNA levels of the proinflammatory cytokines interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α, and their receptors TNFR1, IL-1R1, and the antagonist IL-1RA were significantly higher in the lymphocytes of patients with BP compared with normal controls.

CONCLUSIONS

This study suggests that the observed abnormalities of membrane-bound cytokine receptors may alter the functional response of cytokines in BP and that the mRNA levels of these receptors could be a potential biomarker.