Peripheral inflammation during abnormal mood states in bipolar I disorder

Niacin and its metabolites as master regulators of macrophage activation

Niacin is a broad-spectrum lipid-regulating drug used for clinical therapy of chronic high-grade inflammatory diseases. However, the mechanisms by which either niacin or the byproducts of its catabolism ameliorate these inflammatory diseases are not clear yet. Human circulating monocytes and mature macrophages were used to analyze the effects of niacin and its metabolites (NAM, NUA and 2-Pyr) on oxidative stress, plasticity and inflammatory response by using biochemical, flow cytometry, quantitative real-time PCR and Western blot technologies. Niacin, NAM and 2-Pyr significantly decreased ROS, NO and NOS2 expression in LPS-treated human mature macrophages. Niacin and NAM skewed macrophage polarization toward antiinflammatory M2 macrophage whereas a trend toward proinflammatory M1 macrophage was noted following treatment with NUA. Niacin and NAM also reduced the inflammatory competence of LPS-treated human mature macrophages and promoted bias toward antiinflammatory CD14⁺CD16⁺⁺ nonclassical human primary monocytes. This study reveals for the first time that niacin and its metabolites possess antioxidant, reprogramming and antiinflammatory properties on human primary monocytes and monocyte-derived macrophages. Our findings imply a new understanding of the mechanisms by which niacin and its metabolites favor a continuous and gradual plasticity process in the human monocyte/macrophage system.

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.

Growth factors as clinical biomarkers of prognosis and diagnosis in psychiatric disorders

The psychiatric disorders are one of the most disabling illnesses in the world and represent a major problem for public health. These disorders are characterized by neuroanatomical or biochemical changes and it has been suggested that such changes may be due to inadequate neurodevelopment. Diverse alterations in the gene expression and/or serum level of specific growth factors have been implicated in the etiology, symptoms and progression of some psychiatric disorders. Herein, we summarize the latest information regarding the role of brain-derived neurotrophic factor (BDNF), epidermal growth factor (EGF), fibroblast growth factor (FGF), Insulin-like growth factor (IGF-1), neuroregulin-1 (NGR-1), erythropoietin (EPO), vascular growth factor (VEGF), transforming growth factor beta (TGF-β), nerve growth factor (NGF) and others cytokines in the pathogenesis of schizophrenia, depression, bipolar and anxiety disorders. Focusing on the role of these growth factors and their relationship with the main impairments (cognitive, emotional and social) of these pathologies. Some of these signaling molecules may be suitable biological markers for diagnosis and prognosis in cognitive, mood and social disabilities across different mental disorders.

Mast cell activation disease and the modern epidemic of chronic inflammatory disease

A large and growing portion of the human population, especially in developed countries, suffers 1 or more chronic, often quite burdensome ailments which either are overtly inflammatory in nature or are suspected to be of inflammatory origin, but for which investigations to date have failed to identify specific causes, let alone unifying mechanisms underlying the multiple such ailments that often afflict such patients. Relatively recently described as a non-neoplastic cousin of the rare hematologic disease mastocytosis, mast cell (MC) activation syndrome-suspected to be of greatly heterogeneous, complex acquired clonality in many cases-is a potential underlying/unifying explanation for a diverse assortment of inflammatory ailments. A brief review of MC biology and how aberrant primary MC activation might lead to such a vast range of illness is presented.

A meta-analysis and systematic review of the comorbidity between irritable bowel syndrome and bipolar disorder

Irritable bowel syndrome (IBS) and bipolar disorder (BD) are 2 distinct diseases but may share a similar pathophysiology. However, the comorbidity rate of these 2 diseases is unclear. Also, the current practice guidelines suggest prescribing antidepressants to IBS patients. However, this practice may increase the risk of phase-shift to manic episodes in IBS patients comorbid with BD.This study aimed to determine the relationship between IBS and BD through a meta-analysis.Electronic research through PubMed, Medline, ScienceDirect online, ClinicalTrials.gov, and additional resources.The inclusion criteria were studies investigating the prevalence rate of BD in subjects with IBS and control subjects; and articles on clinical trials on humans.Data from included studies were pooled by a random effects model, and possible confounding variables were examined by meta-regression and subgroup analysis.The current study consists of a total of 177,117 IBS patients and 192,092 control subjects extracted from 6 included studies. The prevalence rate of BD was significantly higher in the IBS patients than in the controls (odds ratio = 2.48, 95% confidence interval: 2.35-2.61, P < 0.001). However, the significance persists only in studies from database research, but not from primary studies. In addition, there was no significant association between the prevalence rate of BD in IBS and several clinical variables, including age, female proportion, prevalence of comorbid diabetes, or hypertension.The total number of included studies is small. Moreover, apparently different results from database research and primary research limit the generalization of our findings to a broad population. Also, we could only perform meta-regression on limited clinical variables.Our results support a significantly higher prevalence rate of BD in IBS patients than in controls. Clinicians should be cautious about the risk of phase-shift to manic episodes when prescribing antidepressants in IBS patients under current practice guidelines.

Depressive symptoms and muscular fitness contribute independently to the ability to perform daily life activities in people with bipolar disorder

BACKGROUND

Compared with healthy controls, people with bipolar disorder experience muscle weakness. The extent to which muscle weakness influences the performance of daily life activities such as walking in people with bipolar disorder requiring hospitalization is unclear.

AIMS

The primary aim of the current study was to explore whether depressive symptoms and muscular fitness independently contribute to the walking capacity in people with bipolar disorder. A secondary aim was to identify variables that could explain the variability in muscular fitness.

METHODS

Forty-two inpatients with bipolar disorder performed a standing broad jump test (SBJ), a measure of muscular performance, and the six minute walk test (6MWT) in addition to the International Physical Activity Questionnaire (IPAQ), the Depressive Symptomatology Self Report (QIDS) and a full-fasting metabolic screening.

RESULTS

The correlation between the 6MWT (595.0 ± 127.3m) and SBJ (126.2 ± 48.6m) was high (r = 0.72, p < 0.001). In backward regression analyzes, 82.3% of the variance in 6MWT was explained by SJB, QIDS (7.6 ± 5.1) and the presence of metabolic syndrome (n = 16; 38%), while 83.0% of the variance in SBJ-score was explained by age, and the QIDS and IPAQ (1435.3 ± 1179.8 MET-min/week) scores.

CONCLUSIONS

Depressive symptoms and muscular fitness contribute independently to daily life functioning in people with bipolar disorder. Thus, muscular rehabilitation strategies might offer a strategy for improving performance of daily life activities in this group.

Cytokines, brain-derived neurotrophic factor and C-reactive protein in bipolar I disorder - Results from a prospective study

BACKGROUND

Peripheral blood brain-derived neurotrophic factor (BDNF) and inflammatory markers may reflect key pathophysiological mechanisms in bipolar disorder in relation to disease activity and neuroprogression.

AIMS

To investigate whether neutrophins and inflammatory marker vary with mood states and are increased in patients with bipolar disorder type I during euthymia as well as in all affective states as a group, compared to levels in healthy control subjects.

METHODS

In a prospective 6-12 months follow-up study, we investigated state specific, intra-individual alterations in levels of BDNF, hsCRP, IL-1β, IL-6, IL-8, IL-18 and TNF-α in 60 patients with bipolar I disorder with an acute severe manic index episode and in subsequent euthymic and depressive and manic states and compared with repeated measurements in healthy control subjects. Data were analysed with linear mixed effects model and with adjustment for gender, age, BMI, alcohol intake and smoking.

RESULTS

From inclusion to end of the 6-12 months follow-up, samples of blood were drawn from the 60 patients during a total of 180 affective states, comprising 57 manic, 11 mixed, 23 depressive and 89 states of euthymia. Further, 69 blood samples were drawn from 35 healthy control subjects with three months apart. In unadjusted mixed-model analysis, levels of IL-6 and IL-8 were increased 64% (b=1.64, 95% CI: 1.31-2.05, p=<0.0001) and 24% (b=1.24, 95% CI: 1.05-1.47, p=0.013), respectively in patients with bipolar disorder overall compared with healthy control subjects. However, in adjusted models, no statistically significant differences were found in any measure between patients and control individuals. Levels of hsCRP in depressive states were decreased with 40% (95% CI: 5-62%, p=0.029) compared with euthymia and with 48% (95% CI: 17-66%, p=0.006) when compared with hypomanic/manic states after adjustment. BDNF and the other inflammatory markers did not vary according to affective state in adjusted mixed models.

LIMITATIONS

Patients were all medicated, specifically with high doses of atypical antipsychotics during the manic index episodes.

CONCLUSIONS

In a sample recruited during hospitalization for acute mania, levels of hsCRP varied according to affective state with higher levels during manic states compared with depressive states.

Mean platelet volume in bipolar disorder: the search for an ideal biomarker

BACKGROUND

The pathophysiology of bipolar disorder (BD) remains a mystery. In this context, interest in the role of the immune and inflammatory systems in BD has been increasing. We aimed to compare the routine hemogram values of BD patients with those of the participants in the healthy control group, to assess the inflammation levels of the two groups. Mean platelet volume (MPV) can be obtained as routine hemogram parameters and may aid in the detection of systemic inflammation.

SUBJECTS AND METHODS

This study was conducted with BD (manic episode) inpatients (n=132) and healthy controls (n=135). Abnormally distributed variables (ie, neutrophil-lymphocyte ratio [NLR], platelet-lymphocyte ratio [PLR], neutrophils, lymphocytes, hemoglobin, hematocrit [HCT], mean corpuscular volume [MCV], mean corpuscular hemoglobin [MCH], mean corpuscular hemoglobin concentration [MCHC], red cell distribution width [RDW], MPV, and plateletcrit [PCT]) were compared using the Mann-Whitney U-test. Student's t-test was used to compare the mean ages and white blood cell, red blood cell, and platelet counts of the patients with BD against those of the participants in the control group.

RESULTS

The comparisons revealed that while the mean WBC and the median NLR, PLR, neutrophil, lymphocyte, MPV, and PCT values were significantly higher in the patients with BD (P<0.05), the median hemoglobin, RBC, HCT, and MCHC values were significantly higher in the control group (P<0.05).

CONCLUSION

Comparisons of hemogram values of patients with BD against those of the healthy control group revealed that inflammatory cells (absolute neutrophil count, platelet count, PCT, and MPV) and ratios (NLR, PLR) seem to be altered during manic episodes. These findings support the hypothesis that inflammatory activation occurs in BD during manic episodes. In addition to NLR and PLR, MPV may be useful in the detection of this activation. The most significant limitation in the study is that smokers were not excluded in both groups. The development of new preventive and therapeutic options can be facilitated through the understanding of this mechanism because through this mechanism, inflammation may pathologically affect brain function, as well as inducing and/or perpetuating BD.

The Neurobiology of Bipolar Disorder: An Integrated Approach

Bipolar disorder is a heterogeneous condition with myriad clinical manifestations and many comorbidities leading to severe disabilities in the biopsychosocial realm. The objective of this review article was to underline recent advances in knowledge regarding the neurobiology of bipolar disorder. A further aim was to draw attention to new therapeutic targets in the treatment of bipolar disorder. To accomplish these goals, an electronic search was undertaken of the PubMed database in August 2015 of literature published during the last 10 years on the pathophysiology of bipolar disorder. A wide-ranging evaluation of the existing work was done with search terms such as "mood disorders and biology," "bipolar disorder and HPA axis," "bipolar disorder and cytokines," "mood disorders and circadian rhythm," "bipolar disorder and oxidative stress," etc. This endeavor showed that bipolar disorder is a diverse condition sharing neurobiological mechanisms with major depressive disorder and psychotic spectrum disorders. There is convincing evidence of crosstalk between different biological systems that act in a deleterious manner causing expression of the disease in genetically predisposed individuals. Inflammatory mediators act in concert with oxidative stress to dysregulate hormonal, metabolic, and circadian homeostasis in precipitating and perpetuating the illness. Stress, whether biologically or psychologically mediated, is responsible for the initiation and progression of the diathesis. Bipolar spectrum disorders have a strong genetic component; severe life stresses acting through various paths cause the illness phenotype.