Effects of symptomatic severity on elevation of plasma soluble interleukin-2 receptor in bipolar mania

Pharmacotherapeutic value of inflammatory and neurotrophic biomarkers in bipolar disorder: A systematic review

BACKGROUND

The various pharmacological interventions, ranging from mood stabilizers and antipsychotics to antidepressants, reflect the diff/iculty of treating depressive/manic symptomatology of bipolar disorder (BD). Among a broad range of mechanisms implicated, immune dysregulation may contribute to the increased inflammation that influences the course of BD. Inflammatory, neurotrophic and oxidative stress factors may be identified as promising peripheral biomarkers in brain functioning, perhaps serving as predictors of an effective response to treatment for BD. The present systematic review aimed to examine the evidence supporting the pharmacotherapeutic value of inflammatory and neurotrophic biomarkers in BD.

METHODS

PubMed, PsychINFO, Scopus and Web of Science were searched from inception to May 2024 by two independent reviewers. A total of 40 studies with 3371 patients with diagnosis and intervention of BD were selected.

RESULTS

Inconsistencies in the effects of pharmacological treatments on the connection between the expected anti-inflammatory response and symptomatologic improvement were identified. Mood stabilizers (lithium), antipsychotics (quetiapine), antidepressants (ketamine) or their combination were described to increase both pro-inflammatory (TNFα, IL-6) and anti-inflammatory (IL-4, IL-8) factors. Other medications, such as memantine and dextromethorphan, autoimmune (infliximab) non-steroidal anti-inflammatory (aspirin, celecoxib) drugs, antidiabetics (pioglitazone), and even dietary supplementation (omega-3), or their combination, clearly decrease inflammatory factors (TNFα, IL-6, IL-1β, C-reactive protein) and/or increase the neurotrophic factor BDNF in BD patients.

CONCLUSION

Inflammation in BD requires further investigation to understand the underlying immunologic mechanism, to identify predictors of treatment response, and to make informed decisions about the use and development of more effective pharmacological interventions for BD.

Hormonal and inflammatory signatures of different mood episodes in bipolar disorder: a large-scale clinical study

BACKGROUND

Bipolar disorder (BD) is characterized by intensive mood fluctuations. While hormones imbalance plays important role in the mood swings, it is unknown whether peripheral hormones profiles could differentiate the manic and depressive mood episodes in BD. In this study, we investigated the changes of various hormones and inflammatory markers across distinct mood episodes of BD in a large clinical study to provide mood episode-specific peripheral biomarkers for BD.

METHODS

A total of 8332 BD patients (n = 2679 depressive episode; n = 5653 manic episode) were included. All patients were in acute state of mood episodes and need hospitalization. A panel of blood tests were performed for levels of sex hormones (serum levels of testosterone, estradiol, and progesterone), stress hormones (adrenocorticotropic hormone and cortisol), and an inflammation marker (C-reactive protein, CRP). A receiver operating characteristic (ROC) curve was used to analyze the discriminatory potential of the biomarkers for mood episodes.

RESULTS

In overall comparison between mood episodes, the BD patients expressed higher levels of testosterone, estradiol, progesterone, and CRP (P < 0.001) and lower adrenocorticotropic hormone (ACTH) level (P < 0.001) during manic episode. The episode-specific changes of testosterone, ACTH, and CRP levels remained between the two groups (P < 0.001) after correction for the confounding factors including age, sex, BMI, occupation, marital status, tobacco use, alcohol consumption, psychotic symptoms, and age at onset. Furthermore, we found a sex- and age-specific impact of combined biomarkers in mood episodes in male BD patients aged ≥ 45 years (AUC = 0.70, 95% CI, 0.634-0.747), not in females.

CONCLUSIONS

While both hormone and inflammatory change is independently associated with mood episodes, we found that the combination of sex hormones, stress hormones and CRP could be more effective to differentiate the manic and depressive episode. The biological signatures of mood episodes in BD patients may be sex- and age-specific. Our findings not only provide mood episode-related biological markers, but also better support for targeted intervention in BD treatments.

Immune marker levels in severe mental disorders: associations with polygenic risk scores of related mental phenotypes and psoriasis

Several lines of evidence implicate immune abnormalities in the pathophysiology of severe mental disorders (SMD) and comorbid mental disorders. Here, we use the data from genome-wide association studies (GWAS) of autoimmune diseases and mental phenotypes associated with SMD to disentangle genetic susceptibilities of immune abnormalities in SMD. We included 1004 patients with SMD and 947 healthy controls (HC) and measured plasma levels of IL-1Ra, sIL-2R, gp130, sTNFR-1, IL-18, APRIL, and ICAM-1. Polygenic risk scores (PRS) of six autoimmune disorders, CRP, and 10 SMD-related mental phenotypes were calculated from GWAS. General linear models were applied to assess the association of PRS with immune marker abnormalities. We found negative associations between PRS of educational attainment and IL-1Ra (P = 0.01) and IL-18 (P = 0.01). There were nominal positive associations between PRS of psoriasis and sgp130 (P = 0.02) and PRS of anxiety and IL-18 (P = 0.03), and nominal negative associations between PRS of anxiety and sIL-2R (P = 0.02) and PRS of educational attainment and sIL-2R (P = 0.03). Associations explained minor amounts of the immune marker plasma-level difference between SMD and HC. Different PRS and immune marker associations in the SMD group compared to HC were shown for PRS of extraversion and IL-1Ra ([interaction effect (IE), P = 0.002), and nominally for PRS of openness and IL-1Ra (IE, P = 0.02) and sTNFR-1 (IE, P = 0.04). Our findings indicate polygenic susceptibilities to immune abnormalities in SMD involving genetic overlap with SMD-related mental phenotypes and psoriasis. Associations might suggest immune genetic factors of SMD subgroups characterized by autoimmune or specific mental features.

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.

Transcriptomic Deconvolution of Dorsal Striata Reveals Increased Monocyte Fractions in Bipolar Disorder

Introduction

Accumulating evidence suggests a relationship between the immune system, neuroinflammation, and mood disorders such as bipolar disorder (BD). However, the immunological landscape of critical brain structures implicated with BD, such as the dorsal striatum, has yet to be characterized. This study sought to investigate the immunological composition of dorsal striata in patients with BD.

Methods

CIBERSORTx, an established RNA deconvolution algorithm, was applied on RNA-sequencing data developed from dorsal striata of 18 BD patients and 17 controls. A validated gene signature matrix for 22 human hematopoietic cell subsets was used to infer the relative proportions of immune cells that were present in the original brain tissue.

Results

Deconvolution of the bulk gene expression data showed that dorsal striata from BD subjects had a significantly greater relative abundance of monocytes compared to control samples.

Conclusion

Monocytes may play a role in the pathogenesis of BD in dorsal striata. Further studies are warranted to confirm the computational results presented herein.

The severity of inflammation in major neuropsychiatric disorders: comparison of neutrophil-lymphocyte and platelet-lymphocyte ratios between schizophrenia, bipolar mania, bipolar depression, major depressive disorder, and obsessive compulsive disorder

BACKGROUND

As non-specific markers of immune dysregulation, neutrophil-lymphocyte and platelet-lymphocyte ratios (NLR and PLR) have been consistently shown to be increased in major neuropsychiatric disorders. Although this increase seems to be trans-diagnostic, the extent to which its magnitude differs between disorders remains largely unclear.

AIM

The aim of this study was to directly compare the severity of inflammation (as reflected by NLR and PLR) between schizophrenia (Sch), bipolar mania (BD-M), bipolar depression (BD-D), major depressive disorder (MDD) and obsessive compulsive disorder (OCD).

METHODS

NLR and PLR were obtained for a total of 417 subjects (91 Sch, 70 BD-D, 37 BD-M, 93 MDD, 37 OCD, and 95 controls) and analyzed for group differences.

RESULTS

Sch, BD-M, BD-D and MDD presented with significantly higher NLR compared with both OCD and HC. NLR in BD-M was significantly higher than all the remaining groups, whereas Sch, BD-D and MDD presented with comparably elevated NLR. Moreover, BD-M, Sch and MDD had significantly higher PLR compared with HC.

CONCLUSION

These results suggest that the underlying inflammation may be most severe in BD-M, followed by Sch, BD-D and MDD. On the other hand, inflammation may be of negligible intensity in OCD, or at least undetectable by means of NLR or PLR.

Insulin Resistance and Blood-Brain Barrier Dysfunction Underlie Neuroprogression in Bipolar Disorder

Bipolar disorder (BD) often progresses to a more chronic and treatment resistant (neuroprogressive) course. Identifying which patients are at risk could allow for early intervention and prevention. Bipolar disorder is highly comorbid with metabolic disorders including type II diabetes mellitus (T2DM), hypertension, obesity, and dyslipidemia. Our studies have shown that insulin resistance (IR) is present in over 50% of patients with BD and that IR might underlie the progression of BD. While no confirmed predictors exist for identifying which patients with BD are likely to develop a more chronic course, emerging evidence including our own studies suggest that IR and related inflammatory pathways lead to impairments in blood-brain barrier (BBB) functioning. For the first time in living psychiatric patients, we have shown that the severity of BBB leakage is proportional to BD severity and is associated with IR. In this hypothesis paper we (i) highlight the evidence for a key role of IR in BD, (ii) show how IR in BD relates to shared inflammatory pathways, and (iii) hypothesize that these modulations result in BBB leakage and worse outcomes in BD. We further hypothesize that (iv) reversing IR through lifestyle changes or the actions of insulin sensitizing medications such as metformin, or optimizing BBB function using vascular protective drugs, such as losartan, could provide novel strategies for the prevention or treatment of neuroprogressive BD.

Resolvin D1 as a novel anti-inflammatory marker in manic, depressive and euthymic states of bipolar disorder

Background: Resolvin D1 (RvD1) is a soluble mediator, which is the metabolite of docosahexaenoic acid (DHA), an omega-3 fatty acid. It is thought that RvD1 may contribute to the etiology of bipolar disorder (BD) because of its anti-inflammatory and antidepressant effect. In this study, it was aimed to compare the serum RvD1 levels of patients with BD diagnosed manic-depressive-euthymic episodes with those of healthy subjects. The secondary objective of this study is to investigate the relationship between RvD1 measures and inflammatory markers.Methods: We included 121 male patients with BD type I, 44 in a mania, 35 in depression and 42 in euthymic state, and 41 healthy controls. Serum RvD1 levels and inflammation indicators (CRP, neutrophil, leukocyte, and albumin) were measured.Results: When the RvD1 values of patients were compared, the median (interquartile range) RvD1 value was 11.2 (5.2) for manic patients, 11.2 (6.6) for depressive patients, 9.6 (5.6) for euthymic patients and 8.4 (7.7) for the control group. There were statistically significant differences between the groups in terms of RvD1 values (p < .001). After adjustment for age and current state with ANCOVA, there were statistically significant differences between manic vs. control groups and depression vs. control groups (p < .001, p=.047). Also mean CRP measures (p=.029) and neutrophil counts (p=.009) were significantly correlated with log transformed RvD1 levels.Conclusions: Our results of increased anti-inflammatory RvD1 during manic and depressive states suggest RvD1 may serve as a delayed resolvent possibly improving inflammatory imbalance. Further research is needed to confirm our findings.

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.

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.

Proteomic Studies of Psychiatric Disorders

Many diseases result from programming effects in utero. This chapter describes recent advances in proteomic studies which have improved our understanding of the underlying pathophysiological pathways in the major psychiatric disorders, resulting in the development of potential novel biomarker tests. Such tests should be based on measurement of blood-based proteins given the ease of accessibility of this medium and the known connections between the periphery and the central nervous system. Most importantly, emerging biomarker tests should be developed on lab-on-a-chip and other handheld devices to enable point-of-care use. This should help to identify individuals with psychiatric disorders much sooner than ever before, which will allow more rapid treatment options for the best possible patient outcomes.

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.

State-dependent alterations of lipid profiles in patients with bipolar disorder

Objective Serum lipid levels may be associated with the affective severity of bipolar disorder, but data on lipid profiles in Asian patients with bipolar disorder and the lipid alterations in different states of opposite polarities are scant. We investigated the lipid profiles of patients in the acute affective, partial, and full remission state in bipolar mania and depression. Methods The physically healthy patients aged between 18 and 45 years with bipolar I disorder, as well as age-matched healthy normal controls were enrolled. We compared the fasting blood levels of glucose, cholesterol, triglyceride, low-density lipoprotein, and high-density lipoprotein of manic or depressed patients in the acute phase and subsequent partial and full remission with those of their normal controls. Results A total of 32 bipolar manic patients (12 women and 20 men), 32 bipolar depressed participants (18 women and 14 men), and 64 healthy control participants took part in this study. The mean cholesterol level in acute mania was significantly lower than that in acute depression (p < 0.025). The lowest rate of dyslipidemia (hypertriglyceridemia or low high-density lipoprotein cholesterol) was observed in acute bipolar mania. Conclusion Circulating lipid profiles may be easily affected by affective states. The acute manic state may be accompanied by state-dependent lower cholesterol and triglyceride levels relative to that in other mood states.

Factors affecting time to remission for inpatients with bipolar mania - A naturalistic Taiwanese study

BACKGROUND

Bipolar disorder is a complicated and chronic mental disorder. This study investigated factors affecting time to remission for inpatients with bipolar mania after 4 weeks of acute treatment.

METHODS

This naturalistic study recruited inpatients with bipolar mania for acute treatment. Symptom severity was assessed using the Young Mania Rating Scale (YMRS) at weeks 0, 1, 2, 3, and 4. Patients were included if they had had assessments at weeks 0 and 1 Remission was defined as an YMRS score ≤ 12. The Cox regression analysis was used to analyze factors associated with time to remission after 4 weeks of acute treatment.

RESULTS

Four hundred and forty-nine patients entered the analysis. Seventy-one of the 449 subjects (15.8%) reached symptomatic remission within 4 weeks of acute treatment. Using forward multivariate Cox regression analysis, comorbid substance use disorders, earlier age at onset, and greater manic symptom severity at baseline found to be statistically significant predictors of a longer time to reach remission after 4 weeks of treatment.

LIMITATIONS

As a retrospective chart review and naturalistic design, placebo effect and potentially confounding factors such as the possibility of missing records may have limited our results.

CONCLUSIONS

Early identification and intervention with integrated therapy is considered to shorten time to remission for patients at high risk of poor treatment outcome. More studies are needed in other real-world settings to generalize our results.

Proliferation and apoptosis of T lymphocytes in patients with bipolar disorder

The aim of the study was to evaluate proliferation capacity and susceptibility to apoptosis of T lymphocytes of patients with bipolar disorder (BD) and to investigate in vitro influence of two standard mood stabilizers: lithium and valproic acid on these parameters using flow cytometry. Our results show that T lymphocytes of BD patients, especially those treated with lithium, have reduced proliferation capacity compared to healthy people. In vitro studies showed that valproic acid reduces the number of cell divisions and percentages of proliferating cells regardless of health status but mainly in very high dose, while lithium has no significant influence on proliferation capacity of patients’ T lymphocytes. Lymphocytes of BD patients are also more prone to apoptosis compared with healthy individuals which is related to high expression of Bax, a pro-apoptotic protein. In vitro lithium protected patients’ lymphocytes from apoptosis proportionally to dose used. Valproic acid protected lymphocytes of patients from apoptosis mainly in therapeutic concentration. Our results show that mood stabilizers used to prevent relapses of the disease have anti-apoptotic effect on T lymphocytes of BD patients but they are not able to improve their proliferation capacity.

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.

Neuroimmune Biomarkers in Mental Illness

Exploration of neuroimmune mechanisms is vital to the understanding of the pathogenesis and pathophysiology of mental disorders. Inflammatory and immune mechanisms are increasingly understood to underpin a number of neuropsychiatric disorders, with an ever-expanding evidence base drawn from basic science to large-scale epidemiological data. Unravelling of these mechanisms should lead to biomarker discovery and potential new avenues for therapeutics that modulate immunological mechanisms. Identification of neuroimmune biomarkers is vital to improving diagnosis, stratification and treatment of mental disorders. There is an urgent clinical need for new therapeutic approaches with poor treatment response and treatment resistance a major problem for many psychiatric disorders including depression and schizophrenia. Neurodegenerative psychiatric disorders such as Alzheimer's also have clear neuroimmune underpinnings and manifest an urgent clinical need for improvements in diagnosis and research towards transformative disease-modifying treatments. This chapter provides some background on the role of the neuroimmune system in mental illness, exploring the role for biomarkers, in addition to reviewing the current state of knowledge in this exciting field. We also reflect on the inherent challenges and methodological pitfalls faced by research in this field, including the complexity of conceptualising multidimensional mental disorders and the dynamic shifting sands of the immune system.

Immune-based strategies for mood disorders: facts and challenges

INTRODUCTION

Inflammation seems to play a role in the pathophysiology of mood disorders, including major depressive disorder (MDD) and bipolar disorder (BD). In the last years several studies have shown increased levels of inflammatory and/or immune markers in patients with mood disorders. Accordingly, the immune system has become a target of interest for the development of biomarkers and therapeutics for mood disorders. Areas covered: Here, we review the evidence showing low-grade inflammation in mood disorders and the studies evaluating immune-based strategies for the treatment of these conditions. Expert commentary: Clinical trials with non-steroidal anti-inflammatory drugs, polyunsaturated acids, N-acetylcysteine, anti-cytokines, physical activity and probiotics have provided promising results in terms of antidepressant efficacy in patients with MDD and BD. Regarding stem cells, only studies with animal models have been performed so far with interesting pre-clinical results. Due to the preliminary nature of the results, most of the clinical studies need to be replicated and/or confirmed in larger clinical settings, embracing the highly heterogeneous pathophysiology of mood disorders.

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.

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.

A Randomized, Double-Blind Placebo-Controlled Trial on Effectiveness and Safety of Celecoxib Adjunctive Therapy in Adolescents with Acute Bipolar Mania

OBJECTIVE

Recent studies have focused on the role of inflammatory cascades as one of the possible etiologic factors of bipolar disorder. We hypothesize that celecoxib, through its anti-inflammatory properties, may have a therapeutic role in acute bipolar mania.

PATIENTS AND METHODS

Forty-two adolescent inpatients with the diagnosis of acute bipolar mania participated in a parallel, randomized, double-blind controlled trial, and 40 patients underwent an 8-week treatment with either celecoxib (100 mg twice daily) or placebo as an adjunctive treatment to lithium and risperidone. Patients were evaluated using Young Mania Rating Scale (YMRS) at baseline and weeks 2, 4, and 8. The primary outcome measure was to assess the efficacy of celecoxib compared with placebo in improving mania symptoms.

RESULT

General linear model repeated measures showed significant effect for time × treatment interaction on YMRS scores [F (2.54, 96.56) = 3.21, p = 0.03]. Significantly greater improvement was observed in YMRS scores in the celecoxib group compared with the placebo group from baseline YMRS score at week 8 (p = 0.04). Although a 35% greater response to treatment (considering a Clinical Global Impressions-Improvement score of ≤2, very much/much improved) was observed in the celecoxib group compared with the placebo group, the difference did not reach the statistical significance level (p = 0.09). No serious adverse event was reported.

CONCLUSIONS

Celecoxib may be an effective adjuvant therapy in treatment of manic episodes (without psychotic features) of adolescents with bipolar mood disorder. The mood-stabilizing role of this drug might be mediated through its action on inflammatory cascades.

Immune and Neuroendocrine Mechanisms of Stress Vulnerability and Resilience

Diagnostic criteria for mood disorders including major depressive disorder (MDD) largely ignore biological factors in favor of behavioral symptoms. Compounding this paucity of psychiatric biomarkers is a need for therapeutics to adequately treat the 30-50% of MDD patients who are unresponsive to traditional antidepressant medications. Interestingly, MDD is highly prevalent in patients suffering from chronic inflammatory conditions, and MDD patients exhibit higher levels of circulating pro-inflammatory cytokines. Together, these clinical findings suggest a role for the immune system in vulnerability to stress-related psychiatric illness. A growing body of literature also implicates the immune system in stress resilience and coping. In this review, we discuss the mechanisms by which peripheral and central immune cells act on the brain to affect stress-related neurobiological and neuroendocrine responses. We specifically focus on the roles of pro-inflammatory cytokine signaling, peripheral monocyte infiltration, microglial activation, and hypothalamic-pituitary-adrenal axis hyperactivity in stress vulnerability. We also highlight recent evidence suggesting that adaptive immune responses and treatment with immune modulators (exogenous glucocorticoids, humanized antibodies against cytokines) may decrease depressive symptoms and thus represent an attractive alternative to the current antidepressant treatments.

A meta-analysis of blood cytokine network alterations in psychiatric patients: comparisons between schizophrenia, bipolar disorder and depression

Schizophrenia, bipolar disorder and major depressive disorder (MDD) have all been associated with aberrant blood cytokine levels; however, neither the pattern of cytokine alterations nor the impact of clinical status have been compared across disorders. We performed a meta-analysis of blood cytokines in acutely and chronically ill patients with these major psychiatric disorders. Articles were identified by searching the PubMed, PsycInfo and Web of Science, and the reference lists of these studies. Sixty-eight studies met the inclusion criteria (40 schizophrenia, 10 bipolar disorder and 18 MDD) for acutely ill patients. Forty-six studies met the inclusion criteria (18 schizophrenia, 16 bipolar disorder and 12 MDD) for chronically ill patients. Levels of two cytokines (interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α)), one soluble cytokine receptor (sIL-2R), and one cytokine receptor antagonist (IL-1RA) were significantly increased in acutely ill patients with schizophrenia, bipolar mania and MDD compared with controls (P<0.01). Following treatment of the acute illness, IL-6 levels significantly decreased in both schizophrenia and MDD (P<0.01); sIL-2R levels increased in schizophrenia; and IL-1RA levels in bipolar mania decreased. In chronically ill patients, the levels of IL-6 were significantly increased in schizophrenia, euthymic (but not depressed) bipolar disorder and MDD compared with controls (P<0.01). The levels of IL-1β and sIL-2R were significantly increased in both chronic schizophrenia and euthymic bipolar disorder. Overall, there were similarities in the pattern of cytokine alterations in schizophrenia, bipolar disorder and MDD during acute and chronic phases of illness, raising the possibility of common underlying pathways for immune dysfunction. Effects of treatment on cytokines were more robust for schizophrenia and MDD, but were more frequently studied than for acute mania. These findings have important implications for our understanding of the pathophysiology and treatment of major psychiatric disorders.

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.

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.

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.

Peripheral inflammation during abnormal mood states in bipolar I disorder

BACKGROUND

Bipolar disorder carries a substantive morbidity and mortality burden, particularly related to cardiovascular disease. Abnormalities in peripheral inflammatory markers, which have been commonly reported in case-control studies, potentially link these co-morbidities. However, it is not clear whether inflammatory markers change episodically in response to mood states or are indicative of chronic pro-inflammatory activity, regardless of mood, in bipolar disorder.

METHODS

Investigations focused on comparing concentrations of specific inflammatory cytokines associated with immune activation status (primary outcome=tumor necrosis factor alpha (TNF-α)) in 37 participants with bipolar disorder across 3 mood states (mania N=15, depression N=9, normal mood N=13) and 29 controls without a psychiatric disorder (total N=66). Cytokine levels were also compared to T1ρ, a potential neuroimaging marker for inflammation, in select brain regions in a subsample (N=39).

RESULTS

Participants with bipolar disorder and healthy controls did not differ significantly in inflammatory cytokine concentrations. However, compared to cases with normal mood, cases with abnormal mood states (mania and depression) had significantly elevated levels of TNF-α, its soluble receptors (sTNFR1/sTNFR2), other macrophage-derived cytokines (interleukin 1β (IL-1β), IL-6, IL-10, and IL-18) in addition to IL-4, interferon-γ, monocyte chemotactic protein-1, fibroblast growth factor β, and vascular endothelial growth factor. Cytokine levels were not correlated with signals from T1ρ imaging in selected structures (amygdalae, hippocampi, hypothalamus, anterior cingulate gyrus, and middle frontal gyrus).

LIMITATIONS

Participants were not followed prospectively across mood states.

CONCLUSION

Activation of inflammatory markers was found in abnormal mood states of bipolar disorder. Longitudinal study of individuals with mood disorders is needed to confirm these findings and to elucidate the time course of any such changes.

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.

Multiplex immunoassay analysis of plasma shows differences in biomarkers related to manic or mixed mood states in bipolar disorder patients

BACKGROUND

The molecular understanding of bipolar disorder (BD) aetiology has advanced over the last years through the identification of peripheral disease biomarkers. Here, we have attempted to identify plasma biomarkers associated with distinct BD mood states.

METHODS

Plasma from BD patients with either a current manic (n=29) or mixed (n=17) mood state and healthy controls (n=53) were analysed using a multiplex immunoassay platform. A total of 145 hormones, growth factors, transport proteins and inflammatory factors were measured.

RESULTS

Plasma levels of the hormones C-peptide, progesterone and insulin, and the inflammatory protein cancer antigen 125 were altered in both mood states. The hormone peptide YY and the growth factor trafficking protein sortilin were changed only in mania patients. Finally, the inflammatory factors haptoglobin, chemokine CC4 and matrix metalloproteinase 7 were altered specifically in mixed mood patients.

LIMITATIONS

This study was limited by a small sample size, potential confounding effects of multiple drug treatments in the patient groups, and lack of dietary restrictions at sampling.

CONCLUSIONS

Plasma from mania and mixed mood BD patients revealed similar changes in proteins related to insulin signalling, suggesting that these could be trait biomarkers. However, mania patients showed specific changes in hormonal and growth factor functions and mixed mood patients had a higher number of changes in inflammation-related molecules. Further studies of these and other biomarker candidates will increase our understanding of the systemic biological pathways affected in different BD mood states. This could lead to the identification of differential surrogate readouts and potential new drug targets for improved treatment outcomes.

Celecoxib adjunctive therapy for acute bipolar mania: a randomized, double-blind, placebo-controlled trial

OBJECTIVES

Recent research has focused on the inflammatory cascade as a key culprit in the etiology of bipolar disorder. We hypothesized that celecoxib, via its anti-inflammatory properties, may have a therapeutic role in mood disorder.

METHODS

Forty-six inpatients with the diagnosis of acute bipolar mania without psychotic features participated in a parallel, randomized, double-blind, placebo-controlled trial, and underwent six weeks of treatment with either celecoxib (400 mg daily) or placebo as an adjunctive treatment to sodium valproate. Patients were evaluated using the Young Mania Rating Scale (YMRS) and Hamilton Depression Rating Scale (HDRS). The primary outcome measure with respect to efficacy was the mean decrease in YMRS score from baseline to the study endpoint, which was compared between the two groups.

RESULTS

A significant difference was observed in the change in YMRS scores on Day 42 compared to baseline in the two groups (p < 0.001). The changes at the endpoint compared to baseline were -29.78 ± 21.78 (mean ± standard deviation) and -21.78 ± 7.16 for the celecoxib and placebo groups, respectively. A significantly higher remission rate was observed in the celecoxib group (87.0%) than the placebo group (43.5%) at Week 6 (p = 0.005). General linear model repeated measures demonstrated a significant effect for the time × treatment interaction on the YMRS scores [F(2.27,99.98) = 6.67, p = 0.001].

CONCLUSIONS

Celecoxib is an effective adjuvant therapy in the treatment of manic episodes (without psychotic features) of bipolar mood disorder. The mood-stabilizing role of the drug might be mediated via its action on the inflammatory cascade.

The Potential Role of the NLRP3 Inflammasome as a Link between Mitochondrial Complex I Dysfunction and Inflammation in Bipolar Disorder

Mitochondrial dysfunction and activation of the inflammatory system are two of the most consistently reported findings in bipolar disorder (BD). More specifically, altered levels of inflammatory cytokines and decreased levels of mitochondrial complex I subunits have been found in the brain and periphery of patients with BD, which could lead to increased production of mitochondrial reactive oxygen species (ROS). Recent studies have shown that mitochondrial production of ROS and inflammation may be closely linked through a redox sensor known as nod-like receptor pyrin domain-containing 3 (NLRP3). Upon sensing mitochondrial release of ROS, NLRP3 assembles the NLRP3 inflammasome, which releases caspase 1 to begin the inflammatory cascade. In this review, we discuss the potential role of the NLRP3 inflammasome as a link between complex I dysfunction and inflammation in BD and its therapeutic implications.

Taking the fuel out of the fire: evidence for the use of anti-inflammatory agents in the treatment of bipolar disorders

BACKGROUND

Inflammation has emerged as a potentially important factor - and thus putative pharmacological target - in the pathology of bipolar disorders. However to date no systematic evaluations of the efficacy of add on anti-inflammatory treatment for the depressive and manic episodes have been carried out.

METHODS

Sixteen articles were ultimately identified - by computer searches of databases (including PsycINFO, MEDLINE, and EMBASE), supplemented by hand searches and personal communication - as meeting study inclusion criteria.

RESULTS

Anti-manic effects were evaluated in two trials, one of adjunctive n-acetyl cysteine (NAC), one of omega-3 fatty acids (O3FA), and significant improvements only emerged for NAC. Celecoxib had a rapid but short-lived antidepressant effect. Despite limited effects of O3FA on symptoms, imaging data demonstrated alterations in neuronal functioning that might have longer-term therapeutic effects. Evidence was strongest for adjunctive NAC in bipolar depression though conclusions are limited by small sample sizes.

LIMITATIONS

Definitive conclusions are limited by the paucity of data, small study sizes, and the variability in methodology used.

CONCLUSIONS

Current evidence for aspirin or celecoxib is insufficient though further investigation of the potential of celecoxib in early illness onset is warranted. Variable evidence exists for add-on O3FA though an indication of short-term treatment effects on membrane fluidity and neuronal activity suggest longer follow-up assessment is needed. The strongest evidence emerged for NAC in depression and future studies must address the role of illness duration and patients׳ baseline medications on outcomes. Careful consideration of lithium toxicity in the elderly and renal impaired is essential.

Antibody profiling of bipolar disorder using Escherichia coli proteome microarrays

To profile plasma antibodies of patients with bipolar disorder (BD), an E. coli proteome microarray comprising ca. 4200 proteins was used to analyze antibody differences between BD patients and mentally healthy controls (HCs). The plasmas of HCs and patients aged 18-45 years with bipolar I disorder (DSM-IV) in acute mania (BD-A) along with remission (BD-R) were collected. The initial samples consisting of 19 BD-A, 20 BD-R, and 20 HCs were probed with the microarrays. After selecting protein hits that recognized the antibody differences between BD and HC, the proteins were purified to construct BD focus arrays for training diagnosis committees and validation. Additional six BD-A, six BD-R, six HCs, and nine schizophrenic disorder (SZ, as another psychiatric control) samples were individually probed with the BD focus arrays. The trained diagnosis committee in BD-A versus HC combined top six proteins, including rpoA, thrA, flhB, yfcI, ycdU, and ydjL. However, the optimized committees in BD-R versus HC and BD-A versus BD-R were of low accuracy (< 0.6). In the single blind test using another four BD-A, four HC, and four SZ samples, the committee of BD-A versus HC was able to classify BD-A versus HC and SZ with 75% sensitivity and 80% specificity that both HC and SZ were regarded as negative controls. The consensus motif of the six proteins, which form the committee of BD-A versus HC, is [KE]DIL[AG]L[LV]I[NL][IC][SVKH]G[LV][VN][LV] by Gapped Local Alignment of Motifs. We demonstrated that the E. coli proteome microarray is capable of screening BD plasma antibody differences and the selected proteins committee was successfully used for BD diagnosis with 79% accuracy.

Persistent inflammation and its relationship to leptin and insulin in phases of bipolar disorder from acute depression to full remission

OBJECTIVE

A proinflammatory phase with various immunomodulatory mechanisms has been noted in bipolar mania and major depression. Weight gain and increased production of leptin may be associated with immunomodulation and insulin resistance in bipolar disorder. However, immunomodulation and its linkage with leptin and insulin in the depressive episode of bipolar disorder remain unclear. We investigated alterations in inflammatory markers and their relationship with leptin and insulin levels in patients with phases of bipolar disorder from acute depression to full remission.

METHODS

Thirty-two physically healthy bipolar I depressed patients aged <45 years and age- and sex-matched healthy controls participated in this study. We measured their circulating levels of leptin, insulin, high-sensitivity C-reactive protein (hs-CRP), soluble interleukin-2 receptor (sIL-2R), soluble interleukin-6 receptor (sIL-6R), soluble tumor necrosis factor receptor 1 (sTNF-R1), and interleukin-1 receptor antagonist (IL-1Ra) in three phases, i.e., acute depression, subsequent partial remission, and full remission.

RESULTS

In acute depression, subsequent partial remission, and full remission, patients with bipolar disorder had significantly higher mean levels of hs-CRP, IL-1Ra, sTNF-R1, and sIL-2R compared with control subjects. The IL-1Ra and sTNF-R1 levels in various affective phases were significantly correlated to body mass index, leptin level, circulating lipids, and medication status. The sIL-2R levels in the three affective phases were all independent of other inflammatory markers and clinical and laboratory variables. Patients showed no alteration of sIL-6R levels through the depressive episode.

CONCLUSIONS

Patients with bipolar disorder in depressive episodes may exhibit persistent inflammation with elevated levels of hs-CRP, IL-1Ra, sTNF-R1, and sIL-2R but not sIL-6R from the acute phases to full remission. Only sIL-2R production seems to be tightly linked with the pathophysiology of bipolar depression and is independent of insulin and leptin levels.

Common biological mechanisms between bipolar disorder and type 2 diabetes: Focus on inflammation

INTRODUCTION

Bipolar disorder (BD) patients present a 3-5 fold greater risk of developing type 2 diabetes (T2D) compared to general population. The underlying mechanisms for the increased prevalence of T2D in BD population are poorly understood.

OBJECTIVES

The purpose of this review is to critically review evidence suggesting that inflammation may have an important role in the development of both BD and T2D.

RESULTS

The literature covered in this review suggests that inflammatory dysregulation take place among many BD patients. Such dysregulated and low grade chronic inflammatory process may also increase the prevalence of T2D in BD population. Current evidence supports the hypothesis of dysregulated inflammatory processes as a critical upstream event in BD as well as in T2D.

CONCLUSIONS

Inflammation may be a factor for the development of T2D in BD population. The identification of inflammatory markers common to these two medical conditions will enable researchers and clinicians to better understand the etiology of BD and develop treatments that simultaneously target all aspects of this multi-system condition.

Depression and cardiovascular disease: an update on how course of illness may influence risk

Depression constitutes a novel and independent risk factor for cardiovascular disease, which despite extensive support in the literature has been underappreciated. While much of the evidence for depression as a risk factor for cardiovascular disease is based on studies following myocardial infarction, the elevated vascular risk conveyed by depression is not confined to periods following acute coronary syndromes. For that matter, the risk appears across mood disorders with evidence for even greater risk in bipolar disorder. This review summarizes the literature linking depressive disorders to cardiovascular mortality with a focus on how the course of illness of mood disorders may influence this risk. Mood disorders may influence risk over decades of illness in a dose-response to symptom burden, or the persistence of affective symptomatology. This may be mediated through changes in the activity of the autonomic nervous system, the hypothalamic-pituitary-adrenal axis, and inflammatory cytokines. Whether treatment of depression can mitigate this risk is not established although there are suggestions to support this contention, which could be better studied with more effective treatments of depression and larger standardized samples. Directions for future study of mechanisms and treatment are discussed. Regardless of causal mechanisms, persons with depressive disorders and other risk factors for vascular disease represent a neglected, high-risk group for cardiovascular events. In addition to the appropriate treatment for depression, screening and optimized management of traditional risk factors for cardiovascular diseases is necessary.

Cancer incidence in people with affective disorder: nationwide cohort study in Taiwan, 1997-2010

BACKGROUND

Cancer is a serious public health problem worldwide, and its relationship with affective disorders is not clear. Aims To investigate alcohol- and tobacco-related cancer risk among patients with affective disorders in a large Taiwanese cohort.

METHOD

Records of newly admitted patients with affective disorders from January 1997 through December 2002 were retrieved from the Psychiatric Inpatient Medical Claims database in Taiwan. Cancers were stratified by site and grouped into tobacco- or alcohol-related cancers. Standardised incidence ratios (SIRs) were calculated to compare the risk of cancer between those with affective disorders and the general population.

RESULTS

Some 10 207 patients with bipolar disorder and 9826 with major depression were included. The risk of cancer was higher in patients with major depression (SIR = 2.01, 95% CI 1.85-2.19) than in those with bipolar disorder (SIR 1.39, 95% CI 1.26-1.53). The elevated cancer risk among individuals ever admitted to hospital for affective disorders was more pronounced in tobacco- and/or alcohol-related cancers.

CONCLUSIONS

Elevated cancer risk was found in patients who had received in-patient care for affective disorders. They require holistic approaches to lifestyle behaviours and associated cancer risks.

Comparison of inflammatory cytokine levels among type I/type II and manic/hypomanic/euthymic/depressive states of bipolar disorder

OBJECTIVE

Inflammatory cytokines have been suggested to be the trait or state markers of bipolar disorder, but with inconsistent results. This may be related to small sample sizes and poor control of some important confounding factors.

METHODS

Gender/age-matched outpatients with bipolar disorder and normal controls were enrolled. The clinical symptoms were rated using the Montgomery Åsberg Depression Rating Scale and Young Mania Rating Scale. Inflammatory cytokines, including soluble interleukin-6 receptor (sIL-6R), soluble interleukin-2 receptor (sIL-2R), C-reactive protein (CRP), soluble tumor necrosis factor receptor type 1 (sTNF-R1), soluble P-selectin receptor (sP-selectin), and monocyte chemotactic protein-1 (MCP-1), were assessed by enzyme-linked immunosorbent assays.

RESULTS

In total, 130 patients with bipolar disorder and 130 normal subjects were enrolled. Among the patients with bipolar disorder, 77 (59.2%) had bipolar I disorder, 53 (40.8%) had bipolar II disorder; 75 (57.7%) were in a euthymic state, 14 (10.8%) were in a manic/hypomanic state, and 41 (31.5%) were in a depressive state. The 130 bipolar patients had significantly higher levels of all cytokines than the normal controls (all p<0.0001). Using multivariate regression analysis with controlling of age, gender, BMI, smoking, duration of illness, and medication grouping, the patients with bipolar II disorder had significantly lower levels of sTNF-R1 than the patients with bipolar I disorder (p=0.038); the patients in a depressive state had significantly lower levels of sTNF-R1 than the patients in manic/hypomanic and euthymic states (p=0.009).

CONCLUSION

The study supported the association of bipolar disorder with inflammatory dysregulation, and sTNF-R1 may be a potential biomarker for staging bipolar disorder.

Applications of blood-based protein biomarker strategies in the study of psychiatric disorders

Major psychiatric disorders such as schizophrenia, major depressive and bipolar disorders are severe, chronic and debilitating, and are associated with high disease burden and healthcare costs. Currently, diagnoses of these disorders rely on interview-based assessments of subjective self-reported symptoms. Early diagnosis is difficult, misdiagnosis is a frequent occurrence and there are no objective tests that aid in the prediction of individual responses to treatment. Consequently, validated biomarkers are urgently needed to help address these unmet clinical needs. Historically, psychiatric disorders are viewed as brain disorders and consequently only a few researchers have as yet evaluated systemic changes in psychiatric patients. However, promising research has begun to challenge this concept and there is an increasing awareness that disease-related changes can be traced in the peripheral system which may even be involved in the precipitation of disease onset and course. Converging evidence from molecular profiling analysis of blood serum/plasma have revealed robust molecular changes in psychiatric patients, suggesting that these disorders may be detectable in other systems of the body such as the circulating blood. In this review, we discuss the current clinical needs in psychiatry, highlight the importance of biomarkers in the field, and review a representative selection of biomarker studies to highlight opportunities for the implementation of personalized medicine approaches in the field of psychiatry. It is anticipated that the implementation of validated biomarker tests will not only improve the diagnosis and more effective treatment of psychiatric patients, but also improve prognosis and disease outcome.

Inflamed moods: a review of the interactions between inflammation and mood disorders

Mood disorders have been recognized by the World Health Organization (WHO) as the leading cause of disability worldwide. Notwithstanding the established efficacy of conventional mood agents, many treated individuals continue to remain treatment refractory and/or exhibit clinically significant residual symptoms, cognitive dysfunction, and psychosocial impairment. Therefore, a priority research and clinical agenda is to identify pathophysiological mechanisms subserving mood disorders to improve therapeutic efficacy. During the past decade, inflammation has been revisited as an important etiologic factor of mood disorders. Therefore, the purpose of this synthetic review is threefold: 1) to review the evidence for an association between inflammation and mood disorders, 2) to discuss potential pathophysiologic mechanisms that may explain this association and 3) to present novel therapeutic options currently being investigated that target the inflammatory-mood pathway. Accumulating evidence implicates inflammation as a critical mediator in the pathophysiology of mood disorders. Indeed, elevated levels of pro-inflammatory cytokines have been repeatedly demonstrated in both major depressive disorder (MDD) and bipolar disorder (BD) patients. Further, the induction of a pro-inflammatory state in healthy or medically ill subjects induces 'sickness behavior' resembling depressive symptomatology. Potential mechanisms involved include, but are not limited to, direct effects of pro-inflammatory cytokines on monoamine levels, dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis, pathologic microglial cell activation, impaired neuroplasticity and structural and functional brain changes. Anti-inflammatory agents, such as acetyl-salicylic acid (ASA), celecoxib, anti-TNF-α agents, minocycline, curcumin and omega-3 fatty acids, are being investigated for use in mood disorders. Current evidence shows improved outcomes in mood disorder patients when anti-inflammatory agents are used as an adjunct to conventional therapy; however, further research is needed to establish the therapeutic benefit and appropriate dosage.

Inflammatory biomarker profiles of mental disorders and their relation to clinical, social and lifestyle factors

In the last few decades, mental health research has increasingly provided evidence supporting the role of inflammation in pathogenesis, course and treatment of mental disorders. With such a steep incline of research, resulting in a wealth of emerged findings, it has become difficult to follow developments within the field. The present review sets out to present the recent developments and to give an overview of the inflammatory profiles of depression, psychosis and bipolar disorder, as well as variations within these disorders. Moreover, mediating factors such as social environment and childhood experience are discussed, both in terms of their potential in elucidating the complex interface between the inflammation and other closely related biological systems, as well as the possibly confounding impact of various lifestyle factors. Whilst many issues in this fascinating area of research remain to be fully understood and elaborated, all current evidence suggests that inflammation plays a key role in mental disorders and may open up novel avenues for clinical treatment.

Multiplex immunoassay analysis of plasma shows prominent upregulation of growth factor activity pathways linked to GSK3β signaling in bipolar patients

BACKGROUND

Our understanding of bipolar disorder (BD) aetiology has advanced in recent years but our ability to translate this to improve patient care in the clinic is still limited.

METHODS

In this study, we have measured the concentrations of 190 different molecules using sensitive multiplex immunoassays in plasma of 17 BD patients compared to 46 matched control subjects.

RESULTS

The analyses led to the identification of 26 dysregulated proteins in BD patients compared to controls. These molecules were comprised mostly of growth factors, hormones, lipid transport and inflammatory proteins. Decreased apolipoprotein A1 has previously been associated with BD patients and this was confirmed in our study.

LIMITATIONS

The present pilot study was limited by its small sample size, use of multiple drug treatments and the lack of dietary restrictions at the time of sampling.

CONCLUSIONS

Future studies may increase our understanding of BD which will help to pave the way for much-needed patient stratification for better treatment outcomes.

Toward clinically applicable biomarkers in bipolar disorder: focus on BDNF, inflammatory markers, and endothelial function

The importance of biomarkers to many branches of medicine is illustrated by their utility in diagnosis and monitoring treatment response and outcome. There is much enthusiasm in the field of mood disorders on the emergence of clinically relevant biomarkers with several potential targets. While there are generally accepted criteria to establish a biomarker, such approaches are premature for our field as we acquire evidence on the most relevant candidates. A number of components of the inflammatory pathway are supported by published data together with an increasing focus on brain-derived neurotrophic factor. These markers may have measurable impacts on endothelial function, which may be particularly amenable to study in clinical samples. The adolescent population is a key focus as identifying biomarkers before the onset of comorbid medical conditions and which may help direct early intervention seem especially promising. A systematic approach to biomarker development in mood disorders is clearly warranted.

Cytokines in bipolar disorder vs. healthy control subjects: a systematic review and meta-analysis

BACKGROUND

Bipolar disorder may be associated with peripheral immune system dysfunction; however, results in individual studies are conflicting. Our aim was to systematically review evidence of peripheral cytokine alterations in bipolar disorder integrating findings from various affective states.

METHODS

We conducted a meta-analysis of studies comparing peripheral cytokine concentrations in patients with bipolar disorder with healthy control subjects. Results were reported according to the PRISMA statement.

RESULTS

Eighteen studies with a total of 761 bipolar disorder patients and 919 healthy controls were included. Overall, concentrations of soluble Interleukin (IL)-2 receptor (sIL-2R), tumor necrosis factor-α (TNF-α), soluble tumor necrosis factor receptor type 1 (sTNFR1) (p < 0.001 each), sIL-6R (p = 0.01) and IL-4 (p = 0.04) were significantly higher in bipolar patients compared with healthy controls. There were no significant differences between bipolar disorder patients and healthy control subjects for IL-1, IL-2, IL-5, IL-6, IL-8, IL-10, IL-12, IL-1β, IL-1 receptor antagonist (IL-1RA), interferon-γ (IFN-γ), transforming growth factor-β1 (TGF-β1) and sTNFR2.

CONCLUSIONS

Employing a global approach, incorporating evidence across affective states, this meta-analysis found some support for peripheral inflammatory alterations in bipolar disorder. Results were limited by heterogeneity between studies, insufficient standardization and lacking control for confounders in individual studies. Further research exploring the role of the peripheral inflammatory system in relation to neuroinflammation is warranted.

Inflammation and schizophrenia: alterations in cytokine levels and perturbation in antioxidative defense systems

OBJECTIVE

Although several theories have been proposed including developmental/neurodegenerative processes, neurotransmitter abnormalities, viral infection, and immune dysfunction, the exact causative factor of schizophrenia is unclear. A relationship between inflammation and schizophrenia has been supported by abnormal cytokine production and altered antioxidant status. This study was aimed to examine the alterations in serum oxidative-antioxidative status and cytokine levels of schizophrenic patients.

METHODS

A total of 91 schizophrenic patients from Saudi Arabia and 50 age- and sex-matched healthy controls were enrolled in the present study. Fresh blood samples were collected to measure the levels of cytokines and markers of oxidative stress by spectrophotometric assays simultaneously.

RESULTS

We observed that there was a significant increase in the levels of tumor necrosis factor-α, interleukin (IL)-1β, and IL-6 and a decrease in the levels of interferon-γ. Lipid peroxides are elevated in serum, while total-sulfhydryl levels were decreased. Also, the activities of superoxide dismutase and glutathione peroxidase were decreased, while the activities of catalase, glutathione reductase, and myeloperoxidase were found to be elevated in serum.

CONCLUSION

We conclude that inflammation resulting from dysregulation of cytokines and altered antioxidant systems may play a critical role in the etiology of schizophrenia.

Cytokine alterations in bipolar disorder: a meta-analysis of 30 studies

BACKGROUND

We conducted a meta-analysis of studies comparing cytokine concentrations between patients with bipolar disorder (BD) and healthy control subjects (HCs).

METHODS

We searched ISI Web of Science, MEDLINE, BIOSIS Previews, Scopus, Current Contents Connect, and Biological Abstracts for relevant studies. Based on heterogeneity status, we used fixed-effect or restricted maximal likelihood model to perform meta-analysis.

RESULTS

Thirty studies with a total of 2599 participants (1351 BD and 1248 HCs) were eligible for the analysis. Concentrations of interleukin (IL)-4 (p = .008), IL-6 (p = .073), IL-10 (p = .013), soluble IL-2 receptor (sIL-2R; p < .001), sIL-6R (p = .021), tumor necrosis factor (TNF)-α (p = .010), soluble TNF receptor-1 (sTNFR1; p < .001), and IL-1 receptor antagonist (p value in mania < .001 and euthymia = .021) were significantly elevated in patients compared with HCs. Moreover, IL-1β (p = .059), and IL-6 (p = .073) tended to show higher values in patients. Levels of IL-2 (p = .156), interferon (INF)-γ (p = .741), C-C motif ligand 2 (p = .624), and IL-8 (p = .952) did not significantly differ between patients and HCs. Subgroup analysis based on mitogen stimulation status partially or completely resolved heterogeneity for most of the cytokines. Concentrations of IL-2, IL-4, sIL-6R, and INF-γ were unrelated to medication status. Phasic difference was present for TNF-α, sTNFR1, sIL-2R, IL-6, and IL-1RA, whereas it was absent for IL-4 and IL-10.

CONCLUSIONS

This meta-analysis provides evidence for significant elevation of proinflammatory, anti-inflammatory, and regulatory cytokines in BD.

Elevated immune-inflammatory signaling in mood disorders: a new therapeutic target?

Converging translational evidence has implicated elevated immune-inflammatory signaling activity in the pathoetiology of mood disorders, including major depressive disorder and bipolar disorder. This is supported in part by cross-sectional evidence for increased levels of proinflammatory eicosanoids, cytokines and acute-phase proteins during mood episodes, and prospective longitudinal evidence for the emergence of mood symptoms in response to chronic immune-inflammatory activation. In addition, mood-stabilizer and atypical antipsychotic medications downregulate initial components of the immune-inflammatory signaling pathway, and adjunctive treatment with anti-inflammatory agents augment the therapeutic efficacy of antidepressant, mood stabilizer and atypical antipsychotic medications. Potential pathogenic mechanisms linked with elevated immune-inflammatory signaling include perturbations in central serotonin neurotransmission and progressive white matter pathology. Both heritable genetic factors and environmental factors including dietary fatty-acid composition may act in concert to sustain elevated immune-inflammatory signaling. Collectively, these data suggest that elevated immune-inflammatory signaling is a mechanism that is relevant to the pathoetiology of mood disorders, and may therefore represent a new therapeutic target for the development of more effective treatments.