Revisiting inflammation in bipolar disorder

Treatment-induced mood switching in affective disorders

Many patients under treatment for mood disorders, in particular patients with bipolar mood disorders, experience episodes of mood switching from one state to another. Various hypotheses have been proposed to explain the mechanism of mood switching, spontaneously or induced by drug treatment. Animal models have also been used to test the role of psychotropic drugs in the switching of mood states. We examine the possible relationship between the pharmacology of psychotropic drugs and their reported incidents of induced mood switching, with reference to the various hypotheses of mechanisms of mood switching.

ER-mitochondria communication is involved in NLRP3 inflammasome activation under stress conditions in the innate immune system

Endoplasmic reticulum (ER) stress and mitochondrial dysfunction, which are key events in the initiation and/or progression of several diseases, are correlated with alterations at ER-mitochondria contact sites, the so-called "Mitochondria-Associated Membranes" (MAMs). These intracellular structures are also implicated in NLRP3 inflammasome activation which is an important driver of sterile inflammation, however, the underlying molecular basis remains unclear. This work aimed to investigate the role of ER-mitochondria communication during ER stress-induced NLRP3 inflammasome activation in both peripheral and central innate immune systems, by using THP-1 human monocytes and BV2 microglia cells, respectively, as in vitro models. Markers of ER stress, mitochondrial dynamics and mass, as well as NLRP3 inflammasome activation were evaluated by Western Blot, IL-1β secretion was measured by ELISA, and ER-mitochondria contacts were quantified by transmission electron microscopy. Mitochondrial Ca2+ uptake and polarization were analyzed with fluorescent probes, and measurement of aconitase and SOD2 activities monitored mitochondrial ROS accumulation. ER stress was demonstrated to activate the NLRP3 inflammasome in both peripheral and central immune cells. Studies in monocytes indicate that ER stress-induced NLRP3 inflammasome activation occurs by a Ca2+-dependent and ROS-independent mechanism, which is coupled with upregulation of MAMs-resident chaperones, closer ER-mitochondria contacts, as well as mitochondrial depolarization and impaired dynamics. Moreover, enhanced ER stress-induced NLRP3 inflammasome activation in the immune system was found associated with pathological conditions since it was observed in monocytes derived from bipolar disorder (BD) patients, supporting a pro-inflammatory status in BD. In conclusion, by demonstrating that ER-mitochondria communication plays a key role in the response of the innate immune cells to ER stress, this work contributes to elucidate the molecular mechanisms underlying NLRP3 inflammasome activation under stress conditions, and to disclose novel potential therapeutic targets for diseases associated with sterile inflammation.

A serum proteomic study of two case-control cohorts identifies novel biomarkers for bipolar disorder

We set out to identify novel protein associations with potential as clinically viable biomarkers for bipolar disorder. To this end, we used proximity extension assay to analyze 201 unique proteins in blood serum from two independent cohorts comprising patients with bipolar disorder and healthy controls (total n = 493). We identified 32 proteins significantly associated with bipolar disorder in both case-control cohorts after adjusting for relevant covariates. Twenty-two findings are novel to bipolar disorder, but 10 proteins have previously been associated with bipolar disorder: chitinase-3-like protein 1, C-C motif chemokine 3 (CCL3), CCL4, CCL20, CCL25, interleukin 10, growth/differentiation factor-15, matrilysin (MMP-7), pro-adrenomedullin, and TNF-R1. Next, we estimated the variance in serum protein concentrations explained by psychiatric drugs and found that some case-control associations may have been driven by psychiatric drugs. The highest variance explained was observed between lithium use and MMP-7, and in post-hoc analyses and found that the serum concentration of MMP-7 was positively associated with serum lithium concentration, duration of lithium therapy, and inversely associated with estimated glomerular filtration rate in an interaction with lithium. This is noteworthy given that MMP-7 has been suggested as a mediator of renal tubulointerstitial fibrosis, which is characteristic of lithium-induced nephropathy. Finally, we used machine learning to evaluate the classification performance of the studied biomarkers but the average performance in unseen data was fair to moderate (area under the receiver operating curve = 0.72). Taken together, our serum biomarker findings provide novel insight to the etiopathology of bipolar disorder, and we present a suggestive biomarker for lithium-induced nephropathy.

Therapeutic Interventions to Mitigate Mitochondrial Dysfunction and Oxidative Stress–Induced Damage in Patients with Bipolar Disorder

Bipolar disorder (BD) is characterized by mood changes, including recurrent manic, hypomanic, and depressive episodes, which may involve mixed symptoms. Despite the progress in neurobiological research, the pathophysiology of BD has not been extensively described to date. Progress in the understanding of the neurobiology driving BD could help facilitate the discovery of therapeutic targets and biomarkers for its early detection. Oxidative stress (OS), which damages biomolecules and causes mitochondrial and dopamine system dysfunctions, is a persistent finding in patients with BD. Inflammation and immune dysfunction might also play a role in BD pathophysiology. Specific nutrient supplements (nutraceuticals) may target neurobiological pathways suggested to be perturbed in BD, such as inflammation, mitochondrial dysfunction, and OS. Consequently, nutraceuticals may be used in the adjunctive treatment of BD. This paper summarizes the possible roles of OS, mitochondrial dysfunction, and immune system dysregulation in the onset of BD. It then discusses OS-mitigating strategies that may serve as therapeutic interventions for BD. It also analyzes the relationship between diet and BD as well as the use of nutritional interventions in the treatment of BD. In addition, it addresses the use of lithium therapy; novel antipsychotic agents, including clozapine, olanzapine, risperidone, cariprazine, and quetiapine; and anti-inflammatory agents to treat BD. Furthermore, it reviews the efficacy of the most used therapies for BD, such as cognitive–behavioral therapy, bright light therapy, imagery-focused cognitive therapy, and electroconvulsive therapy. A better understanding of the roles of OS, mitochondrial dysfunction, and inflammation in the pathogenesis of bipolar disorder, along with a stronger elucidation of the therapeutic functions of antioxidants, antipsychotics, anti-inflammatory agents, lithium therapy, and light therapies, may lead to improved strategies for the treatment and prevention of bipolar disorder.

Inflammatory markers, brain-derived neurotrophic factor, and the symptomatic course of adolescent bipolar disorder: A prospective repeated-measures study

BACKGROUND

Numerous studies have found elevated pro-inflammatory markers and reduced brain-derived neurotrophic factor (BDNF) during symptomatic episodes of bipolar disorder (BD) in adults. There is a paucity of research examining these markers in youth with BD, or longitudinally in any BD age group.

METHODS

79 adolescents, ages 13-19 years, were enrolled, including 43 symptomatic adolescents with BD and 36 age-matched healthy controls (HC). Blood samples were collected from all participants at intake, and repeatedly from BD participants at pre-specified intervals over the course of two years. Serum was assayed for levels of pro-inflammatory markers (c-reactive protein [CRP], interleukin [IL]-6, tumor necrosis factor alpha [TNF-α]), BDNF and the anti-inflammatory marker, IL-10. Week-by-week severity of mood symptoms was assessed using semi-structured interviews.

RESULTS

Adolescents with BD provided an average of 4.6 blood samples, on average every 5.0 months. During the most severe symptomatic interval (i.e., highest sum of mood symptom scores) among BD adolescents, levels of CRP (p = 0.01) and pro- to anti-inflammatory ratios (CRP/IL-10; p < 0.001 and IL-6/IL-10; p = 0.046) were significantly greater, and IL-10 levels (p = 0.004) were significantly lower, vs. HC. There were no differences between BD and HC in IL-6, TNF-α or BDNF. Within BD participants, higher BDNF (p = 0.01) and IL-10 levels (p = 0.001) significantly predicted greater burden of mood symptoms over the subsequent epoch. Moreover, higher CRP levels (p = 0.009) at intake predicted greater time to recovery from the index symptomatic episode.

CONCLUSIONS

In the first repeated-measures study on this topic in adolescents with BD, we found evidence that CRP, an inexpensive and ubiquitous blood test, may be useful in predicting the prospective course of BD symptoms. Future larger studies are warranted.

Association of Bipolar Disorder With Major Adverse Cardiovascular Events: A Population-Based Historical Cohort Study

OBJECTIVE

This study aimed to assess the association of bipolar disorder (BD) with risk of major adverse cardiac events (MACEs) after adjusting for established cardiovascular disease (CVD) risk factors.

METHODS

We conducted a population-based historical cohort study using the Rochester Epidemiology Project. Patients older than 30 years with a clinical encounter from 1998 to 2000 with no prior MACE, atrial fibrillation, or heart failure were followed up through March 1, 2016. BD diagnosis was validated by chart review. Cox proportional hazards regression models were adjusted for established CVD risk factors, alcohol use disorder, other substance use disorders (SUDs), and major depressive disorder (MDD).

RESULTS

The cohort included 288 individuals with BD (0.81%) and 35,326 individuals without BD as the reference group (Ref). Median (interquartile range) follow-up was 16.5 (14.6-17.5) years. A total of 5636 MACE events occurred (BD, 59; Ref, 5577). Survival analysis showed an association between BD and MACE (median event-free-survival rates: BD, 0.80; Ref, 0.86; log-rank p = .018). Multivariate regression adjusting for age and sex also yielded an association between BD and MACE (hazard ratio [HR] = 1.93; 95% confidence interval [CI] = 1.43-2.52; p < .001). The association remained significant after further adjusting for smoking, diabetes mellitus, hypertension, high-density lipoprotein cholesterol, and body mass index (HR = 1.66; 95% CI = 1.17-2.28; p = .006), and for alcohol use disorder, SUD, and MDD (HR = 1.56; 95% CI = 1.09-2.14; p = .010).

CONCLUSIONS

In this study, BD was associated with an increased risk of MACE, which persisted after adjusting for established CVD risk factors, SUDs, and MDD. These results suggest that BD is an independent risk factor for major clinical cardiac disease outcomes.

Treatment-Resistant Bipolar Depression: Therapeutic Trends, Challenges and Future Directions

INTRODUCTION

Bipolar disorder (BD) is a chronic mental illness impacting 1-2% of the population worldwide and causing high rates of functional impairment. Patients with BD spend most of their time in depressive episodes and up to one-third of patients do not respond to adequate doses of medications. Although no consensus exists for definition of treatment-resistant bipolar depression (TRBD), failure of symptoms improvement despite an adequate trial of two therapeutic agents is a common theme of TRBD. In this paper, we review the evidence base of therapeutic interventions, challenges, and potential future directions for TRBD.

METHODS

We conducted a literature search for randomized controlled trials on PubMed for the treatment of TRBD and ongoing trials for the treatment of TRBD/bipolar depression on clinicaltrials.gov.

RESULTS

Several therapeutic agents have been investigated for TRBD. Adjunctive pramipexole and modafinil have data supporting short-term efficacy in TRBD, along with limited data for racemic intravenous ketamine. Celecoxib augmentation of escitalopram and treatment with metformin in patients with insulin resistance showed promising results. Right unilateral electroconvulsive therapy displayed statistically significant response rate and improvement, but not remission compared to pharmacotherapy. Trials for transcranial magnetic stimulation (TMS) have failed to show a significant difference from sham treatment in TRBD.

FUTURE TRENDS

Pharmacological treatments with novel mechanisms of actions like brexpiprazole and vortioxetine are being investigated following successes in unipolar depression. Modified TMS protocols such as accelerated TMS are under investigation. Innovative approaches like psychedelic-assisted psychotherapy, interleukin-2, fecal microbiota transplantation and multipotent stromal cells are being studied.

CONCLUSION

Evidence on current treatment modalities for TRBD is limited with low efficacy. More research is needed for successful treatment of TRBD. Effective therapies and innovative approaches to treatment are being investigated and could show promise.

Human Endogenous Retroviruses as Gene Expression Regulators: Insights from Animal Models into Human Diseases

The human genome contains many retroviral elements called human endogenous retroviruses (HERVs), resulting from the integration of retroviruses throughout evolution. HERVs once were considered inactive junk because they are not replication-competent, primarily localized in the heterochromatin, and silenced by methylation. But HERVs are now clearly shown to actively regulate gene expression in various physiological and pathological conditions such as developmental processes, immune regulation, cancers, autoimmune diseases, and neurological disorders. Recent studies report that HERVs are activated in patients suffering from coronavirus disease 2019 (COVID-19), the current pandemic caused by SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2) infection. In this review, we describe internal and external factors that influence HERV activities. We also present evidence showing the gene regulatory activity of HERV LTRs (long terminal repeats) in model organisms such as mice, rats, zebrafish, and invertebrate models of worms and flies. Finally, we discuss several molecular and cellular pathways involving various transcription factors and receptors, through which HERVs affect downstream cellular and physiological events such as epigenetic modifications, calcium influx, protein phosphorylation, and cytokine release. Understanding how HERVs participate in various physiological and pathological processes will help develop a strategy to generate effective therapeutic approaches targeting HERVs.

Alterations in plasma kynurenine pathway metabolites in children and adolescents with bipolar disorder and unaffected offspring of bipolar parents: A preliminary study

BACKGROUND

There has been growing scientific evidence in recent years that bipolar disorder (BD) is associated with alterations in the kynurenine (KYN) pathway. However, many of these studies have been limited by their focus on adults. Thus, this preliminary study investigated differences in the peripheral levels of KYN metabolites in children and adolescents with BD, unaffected offspring of parents with BD, and healthy controls (HCs).

METHODS

Plasma samples were collected from 49 youths with BD, 19 bipolar offspring, and 31 HCs. Tryptophan (TRP), KYN, and kynurenic acid (KYNA) were separated using electrospray ionization.

RESULTS

One-Way ANCOVA after controlling for age, gender, race, BMI-for-age, and smoking status showed that BD had lower levels of KYN, while unaffected high-risk offspring subjects had lower levels of TRP, KYN, and KYNA when compared to HCs. Moreover, we found that KYN, KYN/TRP, and KYNA/KYN levels predicted the severity of depressive symptoms, while the YMRS score was not associated with any metabolite.

CONCLUSIONS

In summary, this preliminary study has shown that KYN metabolites are decreased in both affected and unaffected subjects, strengthening the idea that the KYN pathway might underlie the familial risk of BD shown by high-risk offspring individuals. However, longitudinal studies are needed to examine whether the alterations observed in this study represent early markers of risk for later developing BD.

Therapeutic approaches employing natural compounds and derivatives for treating bipolar disorder: emphasis on experimental models of the manic phase

Bipolar disorder (BD) is a complex psychiatric disease characterized by mood swings that include episodes of mania and depression. Given its cyclical nature, BD is especially hard to model; however, the standard practice has been to mimic manic episodes in animal models. Despite scientific advances, the pathophysiology of BD is not fully understood, and treatment remains limited. In the last years, natural products have emerged as potential neuroprotective agents for the treatment of psychiatric diseases. Thus, the aim of this review was to explore the therapeutic potential of natural compounds and derivatives against BD, taking into account preclinical and clinical studies. Reliable articles indexed in databases such as PubMed, Web of Science and Science Direct were used. In clinical studies, treatment with herbal plants extracts, omega-3, inositol, n-acetylcysteine and vitamin D has been associated with a clinical improvement in symptoms of mania and depression in BD patients. In animal models, it has been shown that red fruits extracts, curcumin, quercetin, gallic acid, alpha-lipoic acid and carvone can modulate many neurochemical pathways involved in the pathophysiology of manic episodes. Thus, this review appointed the advances in the consumption of natural compounds and derivatives as an important therapeutic strategy to mitigate the symptoms of BD.

Evaluation of postmortem microarray data in bipolar disorder using traditional data comparison and artificial intelligence reveals novel gene targets

Large-scale microarray studies on post-mortem brain tissues have been utilized to investigate the complex molecular pathology of bipolar disorder. However, a major challenge in characterizing the dysregulation of gene expression in patients with bipolar disorder includes the lack of convergence between different studies, limiting comprehensive understanding from individual results. In this study, we aimed to identify genes that are both validated in published literature and are important classification features of unsupervised machine learning analysis of Stanley Brain Bank microarray database, followed by augmented intelligence method to identify distinct patient molecular subgroups. Through combining traditional literature approaches and machine learning, we identified TBL1XR1, SMARCA2, and CHMP5 to be replicated in 3 of the 4 studies included our analysis. The expression of these genes segregated unique subgroups of patients with bipolar disorder. Our study suggests the involvement of PPARγ pathway regulation in patients with bipolar disorder.

Human iPSC-Derived Glia as a Tool for Neuropsychiatric Research and Drug Development

Neuropsychiatric disorders such as schizophrenia or autism spectrum disorder represent a leading and growing burden on worldwide mental health. Fundamental lack in understanding the underlying pathobiology compromises efficient drug development despite the immense medical need. So far, antipsychotic drugs reduce symptom severity and enhance quality of life, but there is no cure available. On the molecular level, schizophrenia and autism spectrum disorders correlate with compromised neuronal phenotypes. There is increasing evidence that aberrant neuroinflammatory responses of glial cells account for synaptic pathologies through deregulated communication and reciprocal modulation. Consequently, microglia and astrocytes emerge as central targets for anti-inflammatory treatment to preserve organization and homeostasis of the central nervous system. Studying the impact of neuroinflammation in the context of neuropsychiatric disorders is, however, limited by the lack of relevant human cellular test systems that are able to represent the dynamic cellular processes and molecular changes observed in human tissue. Today, patient-derived induced pluripotent stem cells offer the opportunity to study neuroinflammatory mechanisms in vitro that comprise the genetic background of affected patients. In this review, we summarize the major findings of iPSC-based microglia and astrocyte research in the context of neuropsychiatric diseases and highlight the benefit of 2D and 3D co-culture models for the generation of efficient in vitro models for target screening and drug development.

Exploring real-world evidence to uncover unknown drug benefits and support the discovery of new treatment targets for depressive and bipolar disorders

BACKGROUND

Major depressive and bipolar disorders are associated with impaired quality of life and high economic burden. Although progress has been made in our understanding of the underlying pathophysiology and the development of novel pharmacological treatments, a large unmet need remains for finding effective treatment options. The purpose of this study was to identify potential new mechanisms of actions or treatment targets that could inform future research and development opportunities for major depressive and bipolar disorders.

METHODS

A self-controlled cohort study was conducted to examine associations between 1933 medications and incidence of major depressive and bipolar disorders across four US insurance claims databases. Presence of incident depressive or bipolar disorders were captured for each patient prior to or after drug exposure and incident rate ratios were calculated. Medications that demonstrated ≥50% reduction in risk for both depressive and bipolar disorders within two or more databases were evaluated as potential treatment targets.

RESULTS

Eight medications met our inclusion criteria, which fell into three treatment groups: drugs used in substance use disorders; drugs that affect the cholinergic system; and drugs used for the management of cardiovascular-related conditions.

LIMITATIONS

This study was not designed to confirm a causal association nor inform current clinical practice. Instead, this research and the methods employed intended to be hypothesis generating and help uncover potential treatment pathways that could warrant further investigation.

CONCLUSIONS

Several potential drug targets that could aid further research and discovery into novel treatments for depressive and bipolar disorders were identified.

Mini-review: The anti-aging effects of lithium in bipolar disorder

The medical use of lithium has grown since its initial introduction in the 1800s as a treatment for gout. Today, the divalent cation remains as the pharmacological gold standard in treatment of bipolar disorder (BD) with strong mood stabilizing effects. Lithium has demonstrated efficacy in the treatment of acute affective episodes, in the reduction of affective episode recurrence, and in significantly decreasing the risk of suicide in patients. BD has been consistently associated with clinical signs of accelerated aging, including increased rates of age-related diseases such as cardiovascular diseases, malignancies, and diabetes mellitus. This clinical scenario parallels accelerated aging mechanisms observed on a molecular basis, with studies reporting shortened telomeres, increased oxidative stress, and accelerated epigenetic aging in patients with BD compared to controls. Lithium has proved useful as a potential agent in slowing down this accelerated aging process in BD, potentially reversing effects induced by the disorder. This mini-review summarizes findings of anti-aging mechanisms associated with lithium use and provides a discussion of the clinical implications and perspectives of this evolving field. Despite many promising results, more studies are warranted in order to elucidate the exact mechanism by which lithium may act as an anti-aging agent and the extent to which these mechanisms are relevant to its mood stabilizing properties in BD.

Inflammatory signaling mechanisms in bipolar disorder

Bipolar disorder is a decidedly heterogeneous and multifactorial disease, with a high individual and societal burden. While not all patients display overt markers of elevated inflammation, significant evidence suggests that aberrant immune signaling contributes to all stages of the disease, and likely explains the elevated rates of comorbid inflammatory illnesses seen in this population. While individual systems have been intensely studied and targeted, a relative paucity of attention has been given to the interconnecting role of inflammatory signals therein. This review presents an updated overview of some of the most prominent pathophysiologic mechanisms in bipolar disorder, from mitochondrial, endoplasmic reticular, and calcium homeostasis, to purinergic, kynurenic, and hormonal/neurotransmitter signaling, showing inflammation to act as a powerful nexus between these systems. Several areas with a high degree of mechanistic convergence within this paradigm are highlighted to present promising future targets for therapeutic development and screening.

High-Sensitive c-Reactive Protein Levels in Euthymic Bipolar Patients: Case-Control Study

Bipolar disorder is a chronic, disabling disease that is characterized by the recurrence of thymic episodes. The role of the immune-inflammatory system in the etiopathogenesis of this affection arouses the interest of research. The aim of this work was to determine the plasma levels of the high sensitivity C reactive protein (hs-CRP) in patients with bipolar disorder in remission phase by comparing them to a control group.A case-control cross-sectional study was conducted from 56 subjects with bipolar disorder in clinical remission, and 56 volunteers and healthy control subjects.Mean plasma hs-CRP was significantly higher in patients with bipolar disorder than control subjects. In bipolar patients, a hs-CRP elevation was significantly associated with the disease severity item mean score.Through this study, bipolar disorder appears to be associated with a state of chronic inflammation. This should lead to randomized controlled trials evaluating the value of anti-inflammatory drugs in the management of bipolar disorder.

Human Endogenous Retrovirus as Therapeutic Targets in Neurologic Disease

Human endogenous retroviruses (HERVs) are ancient retroviral DNA sequences established into germline. They contain regulatory elements and encoded proteins few of which may provide benefits to hosts when co-opted as cellular genes. Their tight regulation is mainly achieved by epigenetic mechanisms, which can be altered by environmental factors, e.g., viral infections, leading to HERV activation. The aberrant expression of HERVs associates with neurological diseases, such as multiple sclerosis (MS) or amyotrophic lateral sclerosis (ALS), inflammatory processes and neurodegeneration. This review summarizes the recent advances on the epigenetic mechanisms controlling HERV expression and the pathogenic effects triggered by HERV de-repression. This article ends by describing new, promising therapies, targeting HERV elements, one of which, temelimab, has completed phase II trials with encouraging results in treating MS. The information gathered here may turn helpful in the design of new strategies to unveil epigenetic failures behind HERV-triggered diseases, opening new possibilities for druggable targets and/or for extending the use of temelimab to treat other associated diseases.

Impaired blood-brain barrier in the microbiota-gut-brain axis: Potential role of bipolar susceptibility gene TRANK1

Bipolar disorder (BD) is a common psychiatric illness with high prevalence and disease burden. Accumulating susceptibility genes for BD have been identified in recent years. However, the exact functions of these genes remain largely unknown. Despite its high heritability, gene and environment interaction is commonly accepted as the major contributing factor to BD pathogenesis. Intestine microbiota is increasingly recognized as a critical environmental factor for human health and diseases via the microbiota‐gut‐brain axis. BD individuals showed altered diversity and compositions in the commensal microbiota. In addition to pro‐inflammatory factors, such as interleukin‐6 and tumour necrosis factor‐α, type 1 interferon signalling pathway is also modulated by specific intestinal bacterial strains. Disruption of the microbiota‐gut‐brain axis contributes to peripheral and central nervous system inflammation, which accounts for the BD aetiology. Administration of type 1 interferon can induce the expression of TRANK1, which is associated with elevated circulating biomarkers of the impaired blood‐brain barrier in BD patients. In this review, we focus on the influence of intestine microbiota on the expression of bipolar gene TRANK1 and propose that intestine microbiota‐dependent type 1 interferon signalling is sufficient to induce the over‐expression of TRANK1, consequently causing the compromise of BBB integrity and facilitating the entrance of inflammatory mediators into the brain. Activated neuroinflammation eventually contributes to the occurrence and development of BD. This review provides a new perspective on how gut microbiota participate in the pathogenesis of BD. Future studies are needed to validate these assumptions and develop new treatment targets for BD.

Identification of potential plasma protein biomarkers for bipolar II disorder: a preliminary/exploratory study

The diagnostic peripheral biomarkers are still lacking for the bipolar II disorder (BD-II). We used isobaric tags for relative and absolute quantification technology to identify five upregulated candidate proteins [matrix metallopeptidase 9 (MMP9), phenylalanyl-tRNA synthetase subunit beta (FARSB), peroxiredoxin 2 (PRDX2), carbonic anhydrase 1 (CA-1), and proprotein convertase subtilisin/kexin type 9 (PCSK9)] for the diagnosis of BD-II. We analysed the differences in the plasma levels of these candidate proteins between BD-II patients and controls (BD-II, n = 185; Controls, n = 186) using ELISA. To establish a diagnostic model for the prediction of BD-II, the participants were divided randomly into a training group (BD-II, n = 149; Controls, n = 150) and a testing group (BD-II, n = 36; Controls, n = 36). Significant increases were found in all five protein levels between BD-II and controls in the training group. Logistic regression was analysed to form the composite probability score of the five proteins in the training group. Receiver-operating characteristic curve analysis revealed the diagnostic validity of the probability score [area under curve (AUC) = 0.89, P < 0.001]. The composite probability score of the testing group also showed good diagnostic validity (AUC = 0.86, P < 0.001). We propose that plasma levels of PRDX2, CA-1, FARSB, MMP9, and PCSK9 may be associated with BD-II as potential biomarkers.

COVID-19 vaccination for people with severe mental illness: why, what, and how?

Psychiatric disorders, and especially severe mental illness, are associated with an increased risk of severe acute respiratory syndrome coronavirus 2 infection and COVID-19-related morbidity and mortality. People with severe mental illness should therefore be prioritised in vaccine allocation strategies. Here, we discuss the risk for worse COVID-19 outcomes in this vulnerable group, the effect of severe mental illness and psychotropic medications on vaccination response, the attitudes of people with severe mental illness towards vaccination, and, the potential barriers to, and possible solutions for, an efficient vaccination programme in this population.

Gender Differences in Complete Blood Count and Inflammatory Ratios among Patients with Bipolar Disorder

Background: Evidence suggested that inflammation may be involved in the etiopathogenesis of bipolar disorder (BD), a chronic psychiatric condition affecting around 2–3% of the general population. However, little is known regarding potential gender differences in peripheral biomarkers of BD, such as neutrophil-to-lymphocyte (NLR), platelet-to-lymphocyte (PLR), and monocyte-to-lymphocyte (MLR) ratios. Methods: In total, 197 females and 174 males with BD in different phases (i.e., (hypo)mania, depression, euthymia) were recruited. A blood sample was drawn to perform a complete blood count (CBC). NLR, PLR, and MLR were subsequently calculated, and differences were computed according to the illness phase and gender. Results: PLR was consistently higher in (hypo)manic than depressed patients, in both males and females. No significant gender differences in PLR value were found when considering only (hypo)mania. Conversely, NLR was increased in (hypo)mania only among males, and gender differences were retrieved in the (hypo)manic subgroup. The findings related to MLR were only marginally significant. Higher platelets values were associated with (hypo)mania only in the female group. Basophils and eosinophils appeared gender- but not state-dependent. Conclusions: Our findings provide further evidence that increased PLR levels may be associated with (hypo)mania in bipolar patients, regardless of gender. Moreover, the usefulness of NLR as a peripheral biomarker of BD appeared limited to males while the role of platelets to females. As CBC represents a low-cost and easily accessible test, researchers should investigate in-depth its potential usefulness as a biomarker of BD and other psychiatric disorders.

Nutrition-based interventions for mood disorders

Introduction: 'Nutritional Psychiatry' is an emerging area of research that has great potential as an adjunctive tool for the prevention and treatment of diverse neuropsychiatric disorders. Several nutrition-related aspects, such as obesity, dietary patterns, gut microbiome composition and gut permeability, bioactive food compounds, and nutrients can influence pathways implicated in the pathophysiology of mood disorders.Areas covered: Here, the authors review the current evidence on nutrition-mood interaction and nutrition-based treatments for the two main mood disorders, i.e., major depressive disorder and bipolar disorder.Expert opinion: Consistent evidence from observational studies has pointed out the association between a 'healthy' diet, generally characterized by a higher intake of fruits, vegetables, legumes, nuts, whole grains, and good quality sources of protein (i.e. fish and/or seafood), and decreased risk of mood disorders and the parallel association between a 'Western' diet pattern and increased risk. However, only a few clinical trials have evaluated the effect of nutritional interventions on the treatment of these conditions. The bidirectional interaction between the brain and the gut, named 'brain-gut-microbiome axis' or 'gut-brain axis', plays a key role in the link between nutrition and mood disorders. Therefore, nutrition-based strategies for gut microbiota modulation are promising fields in mood disorders.

Mitochondrial dysfunction as a critical event in the pathophysiology of bipolar disorder

The understanding of the pathophysiology of bipolar disorder (BD) remains modest, despite recent advances in neurobiological research. The mitochondrial dysfunction hypothesis of bipolar disorder has been corroborated by several studies involving postmortem brain analysis, neuroimaging, and specific biomarkers in both rodent models and humans. Evidence suggests that BD might be related to abnormal mitochondrial morphology and dynamics, neuroimmune dysfunction, and atypical mitochondrial metabolism and oxidative stress pathways. Mitochondrial dysfunction in mood disorders is also associated with abnormal Ca2+ levels, glutamate excitotoxicity, an imbalance between pro- and antiapoptotic proteins towards apoptosis, abnormal gene expression of electron transport chain complexes, and decreased ATP synthesis. This paper aims to review and discuss the implications of mitochondrial dysfunction in BD etiology and to explore mitochondria as a potential target for novel therapeutic agents.

A comparison of inflammatory markers in manic and euthymic states of bipolar disorder

OBJECTIVES

The number of studies investigating inflammatory biomarkers in bipolar disorder has increased significantly in recent years. The neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), and monocyte to lymphocyte ratio (MLR) are inexpensive and easy to obtain values used to measure the level of inflammation. This study compared the NLR, PLR, and MLR values in the manic and euthymic phases of the same patients.

METHODS

Patients who met the inclusion criteria and were hospitalized due to bipolar affective disorder manic episodes at the Ondokuz Mayis University Faculty of Medicine inpatient psychiatry clinic between 01.01.2013 and 01.01.2019 were enrolled in the study. One hundred thirteen patients undergoing manic episodes were included. White blood cells, neutrophil, lymphocyte, platelet, and monocyte counts were retrospectively recorded from complete blood count data collected during the hospital stay, and NLR, PLR, and MLR values were calculated from these.

RESULTS

Neutrophil, platelet, and monocyte counts, as well as NLR, PLR, and MLR values were higher in the manic episodes of bipolar disorder compared to the control group. Decreased neutrophil and lymphocyte counts, and decreased NLR, PLR, and MLR were observed in the remission period after-treatment of the manic bipolar disorder episodes. In the euthymic phase of bipolar disorder, however, platelet and monocyte counts and MLR were higher than in the control group.

CONCLUSIONS

The study indicates that NLR and PLR may be used as state markers and that MLR may be used as a trait marker in bipolar disorder.

Gut-brain axis: A matter of concern in neuropsychiatric disorders…!

The gut microbiota is composed of a large number of microbes, usually regarded as commensal bacteria. It has become gradually clear that gastrointestinal microbiota affects gut pathophysiology and the central nervous system (CNS) function by modulating the signaling pathways of the microbiota-gut-brain (MGB) axis. This bidirectional MGB axis communication primarily acts through neuroendocrine, neuroimmune, and autonomic nervous systems (ANS) mechanisms. Accumulating evidence reveals that gut microbiota interacts with the host brain, and its modulation may play a critical role in the pathology of neuropsychiatric disorders. Recently, neuroscience research has established the significance of gut microbiota in the development of brain systems that are essential to stress-related behaviors, including depression and anxiety. Application of modulators of the MGB, such as psychobiotics (e.g., probiotics), prebiotics, and specific diets, may be a promising therapeutic approach for neuropsychiatric disorders. The present review article primarily focuses on the relevant features of the disturbances of the MGB axis in the pathophysiology of neuropsychiatric disorders and its potential mechanisms.

Doxycycline reverses cognitive impairment, neuroinflammation and oxidative imbalance induced by D-amphetamine mania model in mice: A promising drug repurposing for bipolar disorder treatment?

Immune-inflammatory mechanisms are involved in the pathophysiology of bipolar disorder. Tetracyclines present neuroprotective actions based on their anti-inflammatory and microglia suppressant effects. Doxycycline (DOXY) is a tetracycline that demonstrates a better usage profile with protective actions against inflammation and CNS injury. Here, we investigated the effects of DOXY against behavioral, neuroinflammatory, and pro-oxidative changes induced by the d-amphetamine mania model. Adult mice were given d-amphetamine 2.0 mg/kg or saline for 14 days. Between days 8 and 14, received lithium, DOXY (25 or 50 mg/kg), or their combination (lithium+DOXY) on both doses. We collected the brain areas prefrontal cortex (PFC), hippocampus, and amygdala to evaluate inflammatory and oxidative alterations. D-amphetamine induced hyperlocomotion and impairment in recognition and working memory. Lithium reversed hyperlocomotion but could not restore cognitive alterations. DOXY alone (at both doses) or combined with lithium reversed d-amphetamine-induced cognitive changes. DOXY, better than lithium, reversed the d-amphetamine-induced rise in TNFα, MPO, and lipid peroxidation. DOXY reduced the hippocampal expression of Iba1 (a marker of microglial activation), inducible nitric oxide synthase (iNOS), and nitrite. Combined with lithium, DOXY increased the phosphorylated (inactivated) form of GSK3β (Ser9). Therefore, DOXY alone or combined with lithium reversed cognitive impairment and neuroinflammation induced by the mice's d-amphetamine model. This study points to DOXY as a promising adjunctive tool for bipolar disorder treatment focused on cognition and neuroimmune changes. Our data provide the first rationale for clinical trials investigating DOXY therapeutic actions in bipolar disorder mania.

Neuroinflammation in Mood Disorders: Role of Regulatory Immune Cells

Mood disorders are associated with chronic low-grade systemic (sterile) inflammation, with increased plasma levels of pro-inflammatory mediators targeting all tissues including the brain. Importantly, pro-inflammatory cytokines (ex., tumor-necrosis factor alpha [TNF-α], interleukin [IL]-6) regulate mood behavior and cognition by influencing neurotransmitter levels, activating stress-responsive endocrine axes, among other effects. However, the mechanisms underlying this enhanced inflammation are not well understood. There is increasing evidence indicating that impaired immunoregulatory mechanisms may play a role in this context. Patients with mood disorders (major depression [MDD] and bipolar disorder [BD]) have reduced numbers of major regulatory cells of both innate (natural killer regulatory cells and myeloid-derived suppressor cells [MDSCs]) and adaptive immune responses (CD4+CD25+FoxP3+, B regulatory cells). Dysfunctional regulatory immune cells might contribute to systemic and neuroinflammation observed in mood disorders via different mechanisms, such as: (i) failure to develop adequate stress-related responses, (ii) indirectly through microglial activation, (iii) lack of trophic support and pro-cognitive functions of T cells in the brain, and (iv) dysbiosis. In conclusion, maladaptive immunoregulatory mechanisms seem to be involved with both onset and progression of mood disorders. A deeper understanding of these mechanisms may lead to the development of new therapeutic strategies.

COVID-19 impacts the expression of molecular markers associated with neuropsychiatric disorders

Coronavirus disease 2019 (COVID-19) was initially characterized due to its impacts on the respiratory system; however, many recent studies have indicated that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) significantly affects the brain. COVID-19 can cause neurological complications, probably caused by the induction of a cytokine storm, since there is no evidence of neurotropism by SARS-CoV-2. In line with this, the COVID-19 outbreak could accelerate the progression or affect the clinical outcomes of neuropsychiatric conditions. Thus, we analyzed differential gene expression datasets for clinical samples of COVID-19 patients and identified 171 genes that are associated with the pathophysiology of the following neuropsychiatric disorders: alcohol dependence, autism, bipolar disorder, depression, panic disorder, schizophrenia, and sleep disorder. Several of the genes identified are associated with causing some of these conditions (classified as elite genes). Among these elite genes, 9 were found for schizophrenia, 6 for autism, 3 for depression/major depressive disorder, and 2 for alcohol dependence. The patients with the neuropsychiatric conditions associated with the genes identified may require special attention as COVID-19 can deteriorate or accelerate neurochemical dysfunctions, thereby aggravating clinical outcomes.

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COVID-19 can impact the clinical outcomes of neuropsychiatric diseases (NP).

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Molecular markers of NP were differentially expressed in patients with COVID-19.

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Elite genes were found for schizophrenia, autism, depression and alcohol dependence.

Association of pro-inflammatory cytokines with clinical features in euthymic patients with Bipolar-I-Disorder

BACKGROUND

A chronic low-grade inflammatory state appears to be a relevant mechanism in the pathophysiology of bipolar disorder. Pro-inflammatory cytokines may influence disease course and individual symptomatology; and biological markers correlating with illness features may be of utility in clinical decision making during euthymia.

METHODS

51 euthymic outpatients with Bipolar-I-Disorder (BD-I) and 93 healthy controls (HC) were investigated. Comparisons between groups, and correlations with clinical features were performed. Serum concentrations of interleukin-1β (IL-1β), tumor necrosis factor-α (TNF-α), and soluble interleukin-6 receptor (sIL-6R) were evaluated by ELISA under highly standardized conditions. Clinical features included duration of illness, number of previous suicide attempts and mood episodes (manic, hypomanic, depressive), scores of the Young Mania Rating Scale (YMRS), the Inventory of Depressive Symptoms (IDS-30), the Pittsburg Sleep Quality Index (PSQI), and the Global Assessment of Functioning (GAF).

RESULTS

No significant difference in serum concentrations of IL-1β, TNF-α, and sIL-6R between BD-I euthymic patients and HC could be identified. Among euthymic BD-I patients, a positive correlation of r_s = 0.47 (p = 0.004) between levels of IL-1β and IDS-30 score was identified.

LIMITATIONS

The design was cross-sectional, most patients were receiving medication, only 3 cytokines were assessed, only euthymic BD-I patients were evaluated.

CONCLUSIONS

The findings suggest that elevated pro-inflammatory cytokine concentrations are likely state rather than trait markers of BD-I. It also seems unlikely that cytokine concentrations are clinically informative interepisode. An inflammatory component might possibly be involved in the pathophysiology of subsyndromic depression in BD-I, and conceivably of bipolar depression per se.

Neurobiology of bipolar disorders: a review of genetic components, signaling pathways, biochemical changes, and neuroimaging findings

Bipolar disorder (BD) is a chronic mental illness characterized by changes in mood that alternate between mania and hypomania or between depression and mixed states, often associated with functional impairment. Although effective pharmacological and non-pharmacological treatments are available, several patients with BD remain symptomatic. The advance in the understanding of the neurobiology underlying BD could help in the identification of new therapeutic targets as well as biomarkers for early detection, prognosis, and response to treatment in BD. In this review, we discuss genetic, epigenetic, molecular, physiological and neuroimaging findings associated with the neurobiology of BD. Despite the advances in the pathophysiological knowledge of BD, the diagnosis and management of the disease are still essentially clinical. Given the complexity of the brain and the close relationship between environmental exposure and brain function, initiatives that incorporate genetic, epigenetic, molecular, physiological, clinical, environmental data, and brain imaging are necessary to produce information that can be translated into prevention and better outcomes for patients with BD.

How to prevent the malignant progression of bipolar disorder

There is increasing recognition that, in a high percentage of cases, bipolar disorder is a progressive illness. Multiple types of sensitization (or increased reactivity to repetition of the same stimulus) drive illness progression. One of the clearest is that of episode sensitization, where increased numbers of prior episodes are associated with: faster recurrences; more dysfunction; disability; social, educational, and employment deficits; suicide; medical comorbidities; cognitive dysfunction; and an increased incidence of dementia in old age. Repetition of stressors and bouts of substance abuse can also result in sensitization. Each type of sensitization appears to have an epigenetic basis, such that preventing sensitization should minimize the accumulation of adverse epigenetic chemical marks on DNA, histones, and microRNA. New data emphasize the importance of early, consistent intervention after an initial manic episode. The cognitive dysfunction associated with a first episode improves only if there are no further episode recurrences during the next year. A randomized study has also shown that comprehensive multimodal prophylactic intervention for 2 years leads to improvements in illness course extending over a total of 6 years. Intensive treatment of the earliest stages of bipolar disorder can thus exert lasting positive effects on the course of illness.

Reactions of kynurenic acid with hypobromous acid and hypochlorous acid

Kynurenic acid, a tryptophan metabolite, acts as antagonist or agonist of several receptors. Hypobromous acid (HOBr) and hypochlorous acid (HOCl) are generated by eosinophils and neutrophils. At inflammation sites, kynurenic acid may encounter HOBr and HOCl to generate products. When kynurenic acid was incubated with HOBr under neutral conditions, kynurenic acid generated a single product almost exclusively. This was identified as 3-bromokynurenic acid. Kynurenic acid reacted with HOCl, generating two products. The major product was identified as 3-chlorokynurenic acid with its oxidative decarboxylation product, 3-chloro-4-hydroxy-2(1H)-quinolinone as a by-product. Free amino acids suppressed the reactions of kynurenic acid with HOBr and HOCl. Taurine suppressed the HOCl reaction but not the HOBr reaction. An eosinophil peroxidase system containing H₂O₂, NaCl, and NaBr reacted with kynurenic acid, generating 3-bromokynurenic acid under mildly acidic conditions. Although a myeloperoxidase system containing H₂O₂ and NaCl reacted with kynurenic acid to generate 3-chlorokynurenic acid under mildly acidic conditions, the product was altered to 3-bromokynurenic acid by addition of NaBr to the system. These results suggest that 3-bromokynurenic acid and 3-chlorokynurenic acid may be generated from kynurenic acid at inflammation sites in humans, although their formation will be suppressed by coexistent amino acids.

The relationship between epigenetics and microbiota in neuropsychiatric diseases

Microbiota might be considered as a pool for environmental epigenetic factors. Evidence is accumulating that environmental exposures - including microbes, diet, drugs - play a role in the pathogenesis of many neuropsychiatric disorders. Underlying mechanisms are complex, involving the sensitive interplay of genetics with epigenetics, neuroinflammation and the innate immune system. Modifications of microbiota affect neurogenesis and the maturation of microglia, influencing social behavior, stress-related responses and fear learning mechanisms. The excitatory neurons in the medial prefrontal cortex appear to play a key role. The mechanisms through which antibiotics administration may modulate microbiota and, therefore, behavior and neuropsychiatric disorders, may be influenced by several variables such as pre-existing gastrointestinal inflammation, the baseline microbiota composition, diet and stress perception. Probiotics, individualized diet, antibiotics and fecal transplantation could positively modulate the effects of epigenetic factors on neuropsychiatric disorders.

Chemokine alterations in bipolar disorder: A systematic review and meta-analysis

We aimed to perform a systematic review and meta-analysis of studies examining the levels of chemokines in peripheral blood of patients with bipolar disorder (BD) and healthy controls. Meta-analysis was based on random-effects models with Hedges' g as the effect size estimate. We included 13 eligible studies (1221 BD patients and 663 controls). The following chemokines were analysed: interleukin-8 (IL-8), monocyte-chemoattractant protein-1 (MCP-1), eotaxin-1, eotaxin-2 and interferon-γ-induced protein 10 (IP-10). The levels of IL-8 (N = 8, g = 0.26, 95%CI: 0.11-0.41, p < 0.001), MCP-1 (N = 8, g = 0.40, 95%CI: 0.18-0.63), eotaxin-1 (N = 3, g = 0.55, 95%CI: 0.21-0.89, p = 0.001) and IP-10 (N = 4, g = 0.95, 95%CI: 0.67-1.22, p < 0.001) were significantly higher in BD patients as compared with controls. Subgroup analyses revealed that elevated levels of IL-8 (N = 5, g = 0.75, 95%CI: 0.42-1.07, p < 0.001) and MCP-1 (N = 4, g = 0.57, 95%CI: 0.28-0.86, p < 0.001) appeared only in BD patients during their depressive phase. Illness duration was associated with significantly lower levels of IL-8 in meta-regression analysis. In turn, elevated levels of IP-10 were present during euthymia (N = 2, g = 0.76, 95%CI: 0.43-1.10, p < 0.001) but not depression (N = 2, g = 1.81, 95%CI: -0.16 to 3.77, p = 0.072). The analysis of eotaxin-1 levels was mainly based on studies of euthymic BD patients (N = 3). Our results suggest that chemokine alterations in BD might be related to mood state. Elevated levels of IL-8 and MCP-1 might be specific to depression. Available evidence indicates that increased levels of eotaxin-1 and IP-10 appear in euthymia; however, more studies are needed to address these alterations in other mood states.

Eotaxin-1/CCL11 correlates with left superior temporal gyrus in bipolar disorder: A preliminary report suggesting accelerated brain aging

BACKGROUND

Neuropsychiatric disorders have been linked to immune mechanisms. Altered peripheral levels of eotaxin-1/CCL11; a cytokine implicated in allergic reactions and aging process; have been reported in bipolar disorder (BD). Several brain areas, especially the temporal lobe, seem to display volume loss and accelerated aging in BD. This study aimed at exploring potential associations between eotaxins and brain volumes in patients with BD compared to controls.

METHODS

Twenty-two euthymic patients with BD and 22 controls were enrolled in this study. Serum levels of eotaxin-1/CCL11, eotaxin-2/CCL24 and eotaxin-3/CCL26 were determined alongside brain volumes.

RESULTS

There were no differences in the levels of eotaxins between patients and controls. A negative correlation was found between eotaxin-1/CCL11 levels and left-hemisphere's superior-temporal volume only in BD patients, which persisted with covariate adjusted model.

CONCLUSION

This study corroborates the emerging evidence of association between inflammation and brain volumes in BD. Our preliminary results also support the hypothesis of a possible role of eotaxin-1/CCL11 in accelerated brain aging in BD.

Neuroimmune Mechanisms and Sex/Gender-Dependent Effects in the Pathophysiology of Mental Disorders

Innate and adaptive immune mechanisms have emerged as critical regulators of CNS homeostasis and mental health. A plethora of immunologic factors have been reported to interact with emotion- and behavior-related neuronal circuits, modulating susceptibility and resilience to mental disorders. However, it remains unclear whether immune dysregulation is a cardinal causal factor or an outcome of the pathologies associated with mental disorders. Emerging variations in immune regulatory pathways based on sex differences provide an additional framework for discussion in these psychiatric disorders. In this review, we present the current literature pertaining to the effects that disrupted immune pathways have in mental disorder pathophysiology, including immune dysregulation in CNS and periphery, microglial activation, and disturbances of the blood-brain barrier. In addition, we present the suggested origins of such immune dysregulation and discuss the gender and sex influence of the neuroimmune substrates that contribute to mental disorders. The findings challenge the conventional view of these disorders and open the window to a diverse spectrum of innovative therapeutic targets that focus on the immune-specific pathophenotypes in neuronal circuits and behavior. SIGNIFICANCE STATEMENT: The involvement of gender-dependent inflammatory mechanisms on the development of mental pathologies is gaining momentum. This review addresses these novel factors and presents the accumulating evidence introducing microglia and proinflammatory elements as critical components and potential targets for the treatment of mental disorders.

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

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

Effects of inflammation on the kynurenine pathway in schizophrenia - a systematic review

Background

In the last decade, there has been growing evidence that an interaction exists between inflammation and the kynurenine pathway in schizophrenia. Additionally, many authors found microglial activation in cases of schizophrenia due to inflammatory mechanisms related mostly to an increase of pro-inflammatory cytokines. In order to gain new insights into the pathophysiology of schizophrenia, it is important to incorporate the latest published evidence concerning inflammatory mechanisms and kynurenine metabolism. This systematic review aims to collect reliable recent findings within the last decade supporting such a theory.

Methods

A structured search of electronic databases was conducted for publications between 2008 and 2018 to identify eligible studies investigating patients with schizophrenia/psychosis and the relationship between inflammation and kynurenine pathway. Applicable studies were systematically scored using the NIH Quality Assessment Tools. Two researchers independently extracted data on diagnosis (psychosis/schizophrenia), inflammation, and kynurenine/tryptophan metabolites.

Results

Ten eligible articles were identified where seven studies assessed blood samples and three assessed cerebrospinal fluid in schizophrenic patients.

Of these articles:

Four investigated the relationship between immunoglobulins and the kynurenine pathway and found correlations between IgA-mediated responses and levels of tryptophan metabolites (i.e., kynurenine pathway).

Five examined the correlation between cytokines and kynurenine metabolites where three showed a relationship between elevated IL-6, TNF-α concentrations, and the kynurenine pathway.

Only one study discovered correlations between IL-8 and the kynurenine pathway.

Two studies showed correlations with lower concentrations of IL-4 and the kynurenine pathway.

Moreover, this systematic review did not find a significant correlation between CRP (n = 1 study), IFN-γ (n = 3 studies), and the kynurenine pathway in schizophrenia.

Interpretation

These results emphasize how different inflammatory markers can unbalance the tryptophan/kynurenine pathway in schizophrenia. Several tryptophan/kynurenine pathway metabolites are produced which can, in turn, underlie different psychotic and cognitive symptoms via neurotransmission modulation. However, due to heterogeneity and the shortage of eligible articles, they do not robustly converge to the same findings. Hence, we recommend further studies with larger sample sizes to elucidate the possible interactions between the various markers, their blood vs. CSF ratios, and their correlation with schizophrenia symptoms.

Modulation of the inflammatory response benefits treatment-resistant bipolar depression: A randomized clinical trial

OBJECTIVE

The goal of this study was to reduce treatment resistance and enhance antidepressant response in patients with treatment-resistant bipolar depression (TRBDD) by modulating inflammatory activation.

METHODS

Forty-seven TRBDD patients completed a randomized, double-blind, placebo (PBO)-controlled two-arm study using celecoxib (CBX), a cyclooxygenase 2 (COX-2) inhibitor, in combination with escitalopram (ESC). The Hamilton Depression (17-Item) and the Hamilton Anxiety Rating Scales were used to quantify symptom severity. Self-rating instruments included BDI, BAI and QLES-Q questioner. An adverse events inventory was used, and the possibility of bleeding diathesis was monitored. Complete blood count (CBC), prothrombin time (PT), and activated partial thromboplastin time (APTT) were determined. Comparison of mood scores between the CBX and PBO groups were conducted using a mixed ANOVA and an Independent Sample Student t-test.

RESULTS

The CBX adjunctive treatment produced significantly more responders and remitters than the PBO arm. Compared to the PBO group (n = 20), the CBX group (n = 27) experienced lower depression severity through the entire course of the study, showing significant decrease in depression and anxiety scores as early as week 1. Except for initial mild nausea, no adverse events were reported and study medications were well tolerated.

CONCLUSIONS

Modulation of the inflammatory response through targeted inhibition of the enzyme COX-2 by means of CBX reduces TRBDD and augments and accelerates treatment response in an efficacious and safe manner. Future studies should replicate these findings and additionally investigate whether prolonged administration of CBX is required to maintain remission by adding a discontinuation phase to the study design.

TRIAL REGISTRATION

Clinicaltrials.gov ID: NCT01479829.

DNA damage and repair in neuropsychiatric disorders. What do we know and what are the future perspectives?

Over the past two decades, extensive research has been done to elucidate the molecular etiology and pathophysiology of neuropsychiatric disorders. In majority of them, including Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), bipolar disorder (BD), schizophrenia and major depressive disorder, increased oxidative and nitrosative stress was found. This stress is known to induce oxidative damage to biomolecules, including DNA. Accordingly, increased mitochondrial and nuclear DNA, as well as RNA damage, were observed in patients suffering from these diseases. However, recent findings indicate that the patients are characterised by impaired DNA repair pathways, which may suggest that these DNA lesions could be also a result of their insufficient repair. In the current systematic, critical review, we aim to sum up, using available literature, the knowledge about the involvement of nuclear and mitochondrial DNA damage and repair, as well as about damage to RNA in pathoetiology of neuropsychiatric disorders, i.e., AD, PD, ALS, BD, schizophrenia and major depressive disorder, as well as the usefulness of the discussed factors as being diagnostic markers and targets for new therapies. Moreover, we also underline the new directions to which future studies should head to elucidate these phenomena.

Coadministration of lithium and celecoxib attenuates the behavioral alterations and inflammatory processes induced by amphetamine in an animal model of mania

The present study evaluated the effects of the coadministration of lithium (Li) and Cel on inflammatory parameters in an animal model of mania induced by dextroamphetamine (D-amph). It was used Wistar rats 60 days old (250-350 g). The animals (n = 10 per group) received D-amph (2 mg/kg) or saline solution of NaCl 0.9% (Sal) intraperitoneally once a day for 14 days. From day eight until 14, the animals from the D-amph and Sal groups received Li (24 mg/kg), Cel (20 mg/kg), Li + Cel or water via gavage. Behavioral analyses were performed using the open-field test. The levels of IL-1β, IL-4, IL-10, and TNF-α were evaluated. The administration of D-amph induced hyperactivity in the rats, as well increased the IL-4, IL-10, and TNF-α levels in the serum, frontal cortex, and striatum of rats compared to those of the controls, and treatment with Li plus Cel reversed these alterations. In general, the administration of Li or Cel per se did not have effects on the behavioral and biochemical parameters. However, the treatment with Cel per se decreased only the IL-10 levels in the serum of animals. Besides, the treatment with Li or Cel decreased the IL-4 levels in the serum and reversed the effects of D-amph on this parameter in the frontal cortex. The treatment with Li reversed the effects of D-amph on the TNF-α levels in all tissues evaluated, and the administration of Cel reversed this alteration only in the striatum. It can be observed that treatment with Li plus Cel was more effective against damages caused by D-amph when compared to the administration of both treatments per se, suggesting that the coadministration can be more effective to treat BD rather than Li or Cel itself. The treatment with Li plus Cel was effective against the inflammation induced by D-amph.