The impact of neuroimmune dysregulation on neuroprotection and neurotoxicity in psychiatric disorders--relation to drug treatment

Neurotoxic effects of perinatal exposure to Bisphenol F on offspring mice

Bisphenols constitute a diverse group of endocrine-disrupting chemicals (EDCs) that impact hormone activity. Bisphenol F (BPF) is commonly used as a substitute for Bisphenol A (BPA). The disruption of the immune system by EDCs during embryonic brain development has been suggested as a plausible factor to neurodevelopmental disorders. We investigated the neurotoxic effects of perinatal exposure to BPF on offspring mice. Female mice were exposed to BPF through their drinking water on day 0.5 of pregnancy, and this exposure continued until the offspring mice were weaned, throughout the perinatal period. Our findings revealed that exposure to BPF hindered both growth and neurodevelopment in offspring mice, with a more pronounced effect observed in males. Additionally, transcriptomic analysis was conducted on the brains of male offspring mice exposed to high doses of BPF. In summary, our study indicates that perinatal exposure to BPF results in neurodevelopmental impairments in male offspring mice, linked to oxidative stress, inflammatory responses, and immune dysregulation. These findings underscore that BPF may not be a safe substitute for BPA. Thus, there is a pressing need to reevaluate the current regulation of BPF.

Individuals Who Had a Lifetime History of Suicide Attempts and Their Relationships With Inflammation, Severity of Depressive Symptoms, and Childhood Maltreatments

ABSTRACT

Lifetime history of suicide attempts is associated with inflammatory mechanisms, severity of depressive symptoms, and childhood trauma. This cross-sectional study enrolled 54 suicide attempters and 154 nonsuicide attempters. All individuals were assessed through a questionnaire, a structured clinical interview, scales, anthropometric measures, and laboratory biomarkers. Individuals with a history of lifetime suicide attempts showed significant positive correlations regarding soluble tumor necrosis factor receptor 1 and severity of depressive symptoms (p = 0.013), interleukin-1 receptor antagonist and severity of depressive symptoms (p = 0.04), and absenteeism from work and childhood physical abuse (p = 0.012). Suicide attempters also experienced more childhood trauma (sexual abuse, physical abuse, emotional abuse, emotional neglect, and physical neglect) compared with nonsuicide attempters. IL-4 levels were significantly lower in individuals who attempted suicide than in nonsuicidal individuals. Lifetime suicide attempts in major affective disorders were associated with childhood trauma and proinflammatory and anti-inflammatory cytokines.

The Impact of C-3 Side Chain Modifications on Kynurenic Acid: A Behavioral Analysis of Its Analogs in the Motor Domain

The central nervous system (CNS) is the final frontier in drug delivery because of the blood-brain barrier (BBB), which poses significant barriers to the access of most drugs to their targets. Kynurenic acid (KYNA), a tryptophan (Trp) metabolite, plays an important role in behavioral functions, and abnormal KYNA levels have been observed in neuropsychiatric conditions. The current challenge lies in delivering KYNA to the CNS owing to its polar side chain. Recently, C-3 side chain-modified KYNA analogs have been shown to cross the BBB; however, it is unclear whether they retain the biological functions of the parent molecule. This study examined the impact of KYNA analogs, specifically, SZR-72, SZR-104, and the newly developed SZRG-21, on behavior. The analogs were administered intracerebroventricularly (i.c.v.), and their effects on the motor domain were compared with those of KYNA. Specifically, open-field (OF) and rotarod (RR) tests were employed to assess motor activity and skills. SZR-104 increased horizontal exploratory activity in the OF test at a dose of 0.04 μmol/4 μL, while SZR-72 decreased vertical activity at doses of 0.04 and 0.1 μmol/4 μL. In the RR test, however, neither KYNA nor its analogs showed any significant differences in motor skills at either dose. Side chain modification affects affective motor performance and exploratory behavior, as the results show for the first time. In this study, we showed that KYNA analogs alter emotional components such as motor-associated curiosity and emotions. Consequently, drug design necessitates the development of precise strategies to traverse the BBB while paying close attention to modifications in their effects on behavior.

Association of Blood Metabolomics Biomarkers with Brain Metabolites and Patient-Reported Outcomes as a New Approach in Individualized Diagnosis of Schizophrenia

Given its polygenic nature, there is a need for a personalized approach to schizophrenia. The aim of the study was to select laboratory biomarkers from blood, brain imaging, and clinical assessment, with an emphasis on patients' self-report questionnaires. Metabolomics studies of serum samples from 51 patients and 45 healthy volunteers, based on the liquid chromatography-electrospray ionization-mass spectrometry (LC-ESI-MS/MS), led to the identification of 3 biochemical indicators (cortisol, glutamate, lactate) of schizophrenia. These metabolites were sequentially correlated with laboratory tests results, imaging results, and clinical assessment outcomes, including patient self-report outcomes. The hierarchical cluster analysis on the principal components (HCPC) was performed to identify the most homogeneous clinical groups. Significant correlations were noted between blood lactates and 11 clinical and 10 neuroimaging parameters. The increase in lactate and cortisol were significantly associated with a decrease in immunological parameters, especially with the level of reactive lymphocytes. The strongest correlations with the level of blood lactate and cortisol were demonstrated by brain glutamate, N-acetylaspartate and the concentrations of glutamate and glutamine, creatine and phosphocreatine in the prefrontal cortex. Metabolomics studies and the search for associations with brain parameters and self-reported outcomes may provide new diagnostic evidence to specific schizophrenia phenotypes.

Neuroprotective astroglial response to neural damage and its relevance to affective disorders

Astrocytes not only support neuronal function with essential roles in synaptic neurotransmission, action potential propagation, metabolic support, or neuroplastic and developmental adaptations. They also respond to damage or dysfunction in surrounding neurons and oligodendrocytes by releasing neurotrophic factors and other molecules that increase the survival of the supported cells or contribute to mechanisms of structural and molecular restoration. The neuroprotective responsiveness of astrocytes is based on their ability to sense signals of degeneration, metabolic jeopardy and structural damage, and on their aptitude to locally deliver specific molecules to remedy threats to the molecular and structural features of their cellular partners. To the extent that neuronal and other glial cell disturbances are known to occur in affective disorders, astrocyte responsiveness to those disturbances may help to better understand the roles astrocytes play in affective disorders. The astrocytic sensing apparatus supporting those responses involves receptors for neurotransmitters, purines, cell adhesion molecules and growth factors. Astrocytes also share with the immune system the capacity of responding to cytokines released upon neuronal damage. In addition, in responses to specific signals astrocytes release unique factors such as clusterin or humanin that have been shown to exert potent neuroprotective effects. Astrocytes integrate the signals above to further deliver structural lipids, removing toxic metabolites, stabilizing the osmotic environment, normalizing neurotransmitters, providing anti-oxidant protection, facilitating synaptogenesis and acting as barriers to contain varied deleterious signals, some of which have been described in brain regions relevant to affective disorders and related animal models. Since various of the injurious signals that activate astrocytes have been implicated in different aspects of the etiopathology of affective disorders, particularly in relation to the diagnosis of depression, potentiating the corresponding astrocyte neuroprotective responses may provide additional opportunities to improve or complement available pharmacological and behavioral therapies for affective disorders.

Positron Emission Tomography of Neuroimmune Responses in Humans: Insights and Intricacies

The brain's immune system plays a critical role in responding to immune challenges and maintaining homeostasis. However, dysregulated neuroimmune function contributes to neurodegenerative disease and neuropsychiatric conditions. In vivo positron emission tomography (PET) imaging of the neuroimmune system has facilitated a greater understanding of its physiology and the pathology of some neuropsychiatric conditions. This review presents an in-depth look at PET findings from human neuroimmune function studies, highlighting their importance in current neuropsychiatric research. Although the majority of human PET studies feature radiotracers targeting the translocator protein 18 kDa (TSPO), this review also considers studies with other neuroimmune targets, including monoamine oxidase B, cyclooxygenase-1 and cyclooxygenase-2, nitric oxide synthase, and the purinergic P2X7 receptor. Promising new targets, such as colony-stimulating factor 1, Sphingosine-1-phosphate receptor 1, and the purinergic P2Y12 receptor, are also discussed. The significance of validating neuroimmune targets and understanding their function and expression is emphasized in this review to better identify and interpret PET results.

C-Reactive protein and the kynurenic acid to quinolinic acid ratio are independently associated with white matter integrity in major depressive disorder

Kynurenic acid (KynA) and quinolinic acid (QA) are neuroactive kynurenine pathway (KP) metabolites that have neuroprotective and neurotoxic properties, respectively. At least partly as a result of immune activation, the ratio of KynA to QA in the blood is reduced in major depressive disorder (MDD) and has been reported to be positively correlated with gray matter volume in depression. This study examined whether the inflammatory mediator, C-reactive protein (CRP) and the putative neuroprotective index, KynA/QA, were associated with white matter integrity in MDD, and secondly, whether any such associations were independent of each other or whether the effect of CRP was mediated by KynA/QA. One hundred and sixty-six participants in the Tulsa 1000 study with a DSM-V diagnosis of MDD completed diffusion tensor imaging and provided a serum sample for the quantification of CRP, KynA, and QA. Correlational tractography was performed using DSI Studio to map the specific white matter pathways that correlated with CRP and KynA/QA. CRP was negatively related to KynA/QA (standardized beta coefficient, SBC = -0.35 with standard error, Std.E = 0.13, p < 0.01) after controlling for nine possible confounders, i.e., age, sex, body mass index (BMI), medication status, lifetime alcohol use, severity of depression, severity of anxiety, length of illness, and smoking status. Higher concentrations of CRP were associated with decreased white matter integrity (fractional anisotropy, FA) of the bilateral cingulum and fornix after controlling for the nine potential confounders (SBC = -0.43, Std.E = 0.13, p = 0.002). Greater serum KynA/QA was associated with increased white matter integrity of the bilateral fornix, bilateral superior thalamic radiations, corpus callosum, and bilateral cingulum bundles after controlling for the same possible confounders (SBC = 0.26, Std.E = 0.09, p = 0.005). The relationship between CRP and FA was not mediated by KynA/QA. Exploratory analyses also showed that KynA/QA but not CRP was associated with self-reported positive affect, attentiveness, and fatigue measured with the PANASX (SBCs = 0.17-0.23). Taken together, these results are consistent with the hypothesis that within a subgroup of MDD patients, a higher level of systemic inflammation alters the balance of KP metabolism but also raise the possibility that CRP and neuroactive KP metabolites represent independent molecular mechanisms underlying white matter alterations in MDD.

The role of microglia in neuropsychiatric disorders and suicide

This narrative review examines the possible role of microglial cells, first, in neuroinflammation and, second, in schizophrenia, depression, and suicide. Recent research on the interactions between microglia, astrocytes and neurons and their involvement in pathophysiological processes of neuropsychiatric disorders is presented. This review focuses on results from postmortem, positron emission tomography (PET) imaging studies, and animal models of schizophrenia and depression. Third, the effects of antipsychotic and antidepressant drug therapy, and of electroconvulsive therapy on microglial cells are explored and the upcoming development of therapeutic drugs targeting microglia is described. Finally, there is a discussion on the role of microglia in the evolutionary progression of human lineage. This view may contribute to a new understanding of neuropsychiatric disorders.

The role of immunomodulators in treatment-resistant depression: case studies

Depression is a common mental disorder affecting more than 264 million people worldwide. The first-line treatment for most cases of depression are selective serotonin reuptake inhibitors (SSRIs), such as sertraline, reboxetine and fluoxetine. Recently, it has been found that one-quarter of depressed patients have excessive activation of the immune system. This potentially warrants sub-categorisation of depressed patients into inflammatory and non-inflammatory subtypes. Such a sub-category of depression already exists for those not responding to various traditional antidepressants and is known as treatment-resistant depression. Those with treatment-resistant depression are far more likely to have raised inflammatory markers relative to those whose depression is treatment-responsive. Chronic, low-level inflammation seems to trigger depression via a multitude of mechanisms. These include kynurenine pathway and microglial cell activation, resulting in a reduction in hippocampal volume. Raised inflammatory cytokines also cause perturbations in monoaminergic signalling, which perhaps explains the preponderance of treatment resistance in those patients with inflammatory depression. Therefore, if treatment-resistant depression and inflammatory depression are semi-synonymous then it should follow that anti-inflammatory drugs will display high efficacy in both sub-types. Ketamine is a drug recently approved for use in depression in the USA and displays a particularly good response rate in those patients with treatment resistance. It has been suggested that the antidepressant efficacy of ketamine results from its anti-inflammatory effects. Ketamine seems to produce anti-inflammatory effects via polarisation of monocytes to M2 macrophages. Furthermore, another anti-inflammatory drug with potential use in treatment-resistant depression is Celecoxib. Celecoxib is a long-acting, selective COX-2 inhibitor. Early clinical trials show that Celecoxib has an adjuvant effect with traditional antidepressants in treatment-resistant patients. This paper highlights the importance of classifying depressed patients into inflammatory and non-inflammatory subtypes; and how this may lead to the development of more targeted treatments for treatment-resistant depression.

Water Extract of Ecklonia cava Protects against Fine Dust (PM2.5)-Induced Health Damage by Regulating Gut Health

To confirm the therapeutic effect of the water extract from Ecklonia cava (WEE) against PM_2.5 induced systemic health damage, we evaluated gut health with a focus on the microbiota and metabolites. Systemic damage in mice was induced through PM_2.5 exposure for 12 weeks in a whole-body chamber. After exposure for 12 weeks, body weight and food intake decreased, and WEE at 200 mg/kg body weight (mpk) alleviated these metabolic efficiency changes. In addition, PM_2.5 induced changes in the length of the colon and fecal water content. The administration of the WEE at 200 mpk oral dose effectively reduced changes in the colon caused by PM_2.5 exposure. We also attempted to confirm whether the effect of the WEE is mediated via regulation of the microbiota-gut-brain axis in mice with PM_2.5 induced systemic damage. We examined changes in the fecal microbiota and gut metabolites such as short-chain fatty acids (SCFAs) and kynurenine metabolites. In the PM_2.5 exposed group, a decrease in the abundance of Lactobacillus (Family: Lactobacillaceae) and an increase in the abundance of Alistipes (Family: Rikenellaceae) were observed, and the administration of the WEE showed a beneficial effect on the gut microbiota. In addition, the WEE effectively increased the levels of SCFAs (acetate, propionate, and butyrate). Furthermore, kynurenic acid (KYNA), which is a critical neuroprotective metabolite in the gut-brain axis, was increased by the administration of the WEE. Our findings suggest that the WEE could be used as a potential therapeutic against PM_2.5 induced health damage by regulating gut function.

Molecular Mechanisms of Psilocybin and Implications for the Treatment of Depression

Therapeutic deficiencies with monoaminergic antidepressants invites the need to identify and develop novel rapid-acting antidepressants. Hitherto, ketamine and esketamine are identified as safe, well-tolerated rapid-acting antidepressants in adults with treatment-resistant depression, and also mitigate measures of suicidality. Psilocybin is a naturally occurring psychoactive alkaloid and non-selective agonist at many serotonin receptors, especially at serotonin 5-HT_2A receptors, and is found in the Psilocybe genus of mushrooms. Preliminary studies with psilocybin have shown therapeutic promise across diverse populations including major depressive disorder. The pharmacodynamic mechanisms mediating the antidepressant and psychedelic effects of psilocybin are currently unknown but are thought to involve the modulation of the serotonergic system, primarily through agonism at the 5-HT_2A receptors and downstream changes in gene expression. It is also established that indirect effects on dopaminergic and glutamatergic systems are contributory, as well as effects at other lower affinity targets. Along with the direct effects on neurochemical systems, psilocybin alters neural circuitry and key brain regions previously implicated in depression, including the default mode network and amygdala. The aim of this review is to synthesize the current understanding of the receptor pharmacology and neuronal mechanisms underlying the psychedelic and putative antidepressant properties of psilocybin.

Biomarkers of Post-COVID Depression

The COVID-19 pandemic is spreading around the world and 187 million people have already been affected. One of its after-effects is post-COVID depression, which, according to the latest data, affects up to 40% of people who have had SARS-CoV-2 infection. A very important issue for the mental health of the general population is to look for the causes of this complication and its biomarkers. This will help in faster diagnosis and effective treatment of the affected patients. In our work, we focused on the search for major depressive disorder (MDD) biomarkers, which are also present in COVID-19 patients and may influence the development of post-COVID depression. For this purpose, we searched PubMed, Scopus and Google Scholar scientific literature databases using keywords such as 'COVID-19', 'SARS-CoV-2', 'depression', 'post-COVID', 'biomarkers' and others. Among the biomarkers found, the most important that were frequently described are increased levels of interleukin 6 (IL-6), soluble interleukin 6 receptor (sIL-6R), interleukin 1 β (IL-1β), tumor necrosis factor α (TNF-α), interferon gamma (IFN-γ), interleukin 10 (IL-10), interleukin 2 (IL-2), soluble interleukin 2 receptor (sIL-2R), C-reactive protein (CRP), Monocyte Chemoattractant Protein-1 (MCP-1), serum amyloid a (SAA1) and metabolites of the kynurenine pathway, as well as decreased brain derived neurotrophic factor (BDNF) and tryptophan (TRP). The biomarkers identified by us indicate the etiopathogenesis of post-COVID depression analogous to the leading inflammatory hypothesis of MDD.

The kynurenine pathway and bipolar disorder: intersection of the monoaminergic and glutamatergic systems and immune response

Dysfunction in a wide array of systems-including the immune, monoaminergic, and glutamatergic systems-is implicated in the pathophysiology of depression. One potential intersection point for these three systems is the kynurenine (KYN) pathway. This study explored the impact of the prototypic glutamatergic modulator ketamine on the endogenous KYN pathway in individuals with bipolar depression (BD), as well as the relationship between response to ketamine and depression-related behavioral and peripheral inflammatory markers. Thirty-nine participants with treatment-resistant BD (23 F, ages 18-65) received a single ketamine infusion (0.5 mg/kg) over 40 min. KYN pathway analytes-including plasma concentrations of indoleamine 2,3-dioxygenase (IDO), KYN, kynurenic acid (KynA), and quinolinic acid (QA)-were assessed at baseline (pre-infusion), 230 min, day 1, and day 3 post-ketamine. General linear models with restricted maximum likelihood estimation and robust sandwich variance estimators were implemented. A repeated effect of time was used to model the covariance of the residuals with an unstructured matrix. After controlling for age, sex, and body mass index (BMI), post-ketamine IDO levels were significantly lower than baseline at all three time points. Conversely, ketamine treatment significantly increased KYN and KynA levels at days 1 and 3 versus baseline. No change in QA levels was observed post-ketamine. A lower post-ketamine ratio of QA/KYN was observed at day 1. In addition, baseline levels of proinflammatory cytokines and behavioral measures predicted KYN pathway changes post ketamine. The results suggest that, in addition to having rapid and sustained antidepressant effects in BD participants, ketamine also impacts key components of the KYN pathway.

Personality classification enhances blood metabolome analysis and biotyping for major depressive disorders: two-species investigation

BACKGROUND

The relationship between depression and personality has long been suggested, however, biomarker investigations for depression have mostly overlooked this connection.

METHODS

We collected personality traits from 100 drug-free patients with major depressive disorders (MDD) and 100 healthy controls based on the Five-Factor Model (FFM) such as Neuroticism (N) and Extraversion (E), and also obtained 63 plasma metabolites profiles by LCMS-based metabolome analysis.

RESULTS

Partitional clustering analysis using the NEO-FFI data classified all subjects into three major clusters. Eighty-six subjects belonging to Cluster 1 (C1: less personality-biased group) constituted half of MDD patients and half of healthy controls. C2 constituted 50 subjects mainly MDD patients (N ^high + E ^low), and C3 constituted 64 subjects mainly healthy subjects (N ^low + E ^high). Using metabolome information, the machine learning model was optimized to discriminate MDD patients from healthy controls among all subjects and C1, respectively. The performance of the model for all subjects was moderate (AUC = 0. 715), while the performance was extremely improved when limited to C1 (AUC = 0. 907). Tryptophan-pathway plasma metabolites including tryptophan, serotonin and kynurenine were significantly lower in MDD patients especially among C1. We also validated metabolomic findings using a social-defeat mice model of stress-induced depression.

LIMITATIONS

A case-control study design and sample size is not large.

CONCLUSIONS

Our results suggest that personality classification enhances blood biomarker analysis for MDD patients and further translational investigations should be conducted to clarify the biological relationship between personality traits, stress and depression.

The Emerging Role of the Double-Edged Impact of Arachidonic Acid- Derived Eicosanoids in the Neuroinflammatory Background of Depression

Eicosanoids are arachidonic acid (AA) derivatives belonging to a family of lipid signalling mediators that are engaged in both physiological and pathological processes in the brain. Recently, their implication in the prolonged inflammatory response has become a focus of particular interest because, in contrast to acute inflammation, chronic inflammatory processes within the central nervous system (CNS) are crucial for the development of brain pathologies including depression. The synthesis of eicosanoids is catalysed primarily by cyclooxygenases (COX), which are involved in the production of pro-inflammatory AA metabolites, including prostaglandins and thromboxanes. Moreover, eicosanoid synthesis is catalysed by lipoxygenases (LOXs), which generate both leukotrienes and anti-inflammatory derivatives such as lipoxins. Thus, AA metabolites have double- edged pro-inflammatory and anti-inflammatory, pro-resolving properties, and an imbalance between these metabolites has been proposed as a contributor or even the basis for chronic neuroinflammatory effects. This review focuses on important evidence regarding eicosanoid-related pathways (with special emphasis on prostaglandins and lipoxins) that has added a new layer of complexity to the idea of targeting the double-edged AA-derivative pathways for therapeutic benefits in depression. We also sought to explore future research directions that can support a pro-resolving response to control the balance between eicosanoids and thus to reduce the chronic neuroinflammation that underlies at least a portion of depressive disorders.

Peripheral Markers of Depression

Major Depressive Disorder (MDD) is a leading cause of disability worldwide, creating a high medical and socioeconomic burden. There is a growing interest in the biological underpinnings of depression, which are reflected by altered levels of biological markers. Among others, enhanced inflammation has been reported in MDD, as reflected by increased concentrations of inflammatory markers-C-reactive protein, interleukin-6, tumor necrosis factor-α and soluble interleukin-2 receptor. Oxidative and nitrosative stress also plays a role in the pathophysiology of MDD. Notably, increased levels of lipid peroxidation markers are characteristic of MDD. Dysregulation of the stress axis, along with increased cortisol levels, have also been reported in MDD. Alterations in growth factors, with a significant decrease in brain-derived neurotrophic factor and an increase in fibroblast growth factor-2 and insulin-like growth factor-1 concentrations have also been found in MDD. Finally, kynurenine metabolites, increased glutamate and decreased total cholesterol also hold promise as reliable biomarkers for MDD. Research in the field of MDD biomarkers is hindered by insufficient understanding of MDD etiopathogenesis, substantial heterogeneity of the disorder, common co-morbidities and low specificity of biomarkers. The construction of biomarker panels and their evaluation with use of new technologies may have the potential to overcome the above mentioned obstacles.

Effect of immune activation on the kynurenine pathway and depression symptoms - A systematic review and meta-analysis

Dysregulated kynurenine (KYN) pathway has been implicated in the pathophysiology of depression. In this systematic review, we examined the relationship between kynurenine pathway metabolites (KYN, kynurenic acid KYNA, tryptophan TRP, quinolinic acid QUIN, KYN/TRP ratio) and depression symptoms in the context of pro-inflammatory activation and immune response. Out of 5,082 articles, fifteen studies were suitable; ten studies (N = 315 medically ill patients treated with interferon-alpha IFN-α) reported baseline and post-intervention plasma KYN, TRP and KYN/TRP ratios which were included in quantitative meta-analysis. Data from five studies were summarized (IFN-α, interferon-beta IFN-β, and lipopolysaccharide LPS). We found that IFN-α treatment in patients with chronic illnesses was associated with decreased TRP, increased levels of KYN and KYN/TRP ratio and depression scores from baseline to follow-up at both 4 and 24 weeks. Our findings suggest that increased risk of depression observed after immune-activating agents in patients with chronic medical illnesses is likely mediated by the kynurenine pathway. Further prospective studies are required to investigate the exact pathophysiology of the KYN pathway in depression.

Maternal high-fat diet stimulates proinflammatory pathway and increases the expression of Tryptophan Hydroxylase 2 (TPH2) and brain-derived neurotrophic factor (BDNF) in adolescent mice hippocampus

Maternal high-fat diet (HFD) consumption can promote a systemic inflammatory condition that may impair the offspring brain development, damaging memory and learning, when it reaches the hippocampus. This study aims to evaluate maternal HFD effects, during pregnancy and lactation, upon dams/mice offspring nutritional status, protein and gene expression of inflammatory pathway (JNK, pJNK and TNF-α), serotonin system molecules (Tryptophan Hydroxylase 2 (TPH2), key-enzyme of serotonin synthesis, serotonin transporter (SERT); 5-HT1A serotonergic receptor (5-HT1A)) and brain derived neurotrophic factor (BDNF) on recently weaned mice offspring hippocampus. Female Swiss mice were fed a control diet (CD, 11,5% fat) or a HFD (45.0% fat) from pre-mating to lactation. After weaning, the offspring received CD up to 28 post-natal days (PND28). Body weight and visceral adiposity (retroperitoneal and gonadal adipose tissue) of dams and offspring were measured. After euthanasia, the offspring hippocampus was dissected for evaluations of BDNF, inflammatory pathway and serotonergic system molecules protein and gene expression, through the techniques of Western Blotting, RTqPCR and ELISA. Our findings show that, during pregnancy, HFD-dams and HFD-offspring exhibited an increase in body weight gain and visceral adipose tissue compared to control animals. The hippocampus of HFD-offspring showed increased protein expression of TPH2, BDNF, pJNK and increased mRNA levels of TNF-α. However, the TPH2 increase in HFD-offspring did not alter hippocampal serotonin levels quantified through ELISA. Maternal HFD promoted an obesity phenotype in its offspring with increased body weight and visceral adiposity, increased protein and gene expression of the pro-inflammatory proteins pJNK and TNF-α. These changes were accompanied by increased TPH2 and BDNF protein expression. Thus, our findings show that maternal HFD during gestation and lactation increased pJNK and TNF-α expression in their offspring hippocampus indicating a pro-inflammatory state, with increased BDNF expression and alterations in its serotonergic system reflected by increased TPH2 expression.

A Specific Inflammatory Profile Underlying Suicide Risk? Systematic Review of the Main Literature Findings

Consistent evidence indicates the association between inflammatory markers and suicidal behavior. The burden related to immunological differences have been widely documented in both major affective disorders and suicidal behavior. Importantly, abnormally elevated pro-inflammatory cytokines levels have been reported to correlate with suicidal behavior but whether and to what extent specific inflammatory cytokines abnormalities may contribute to our understanding of the complex pathophysiology of suicide is unknown. The present manuscript aimed to systematically review the current literature about the role of pro-inflammatory cytokines in suicidal behavior. Most studies showed a link between abnormally higher interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, transforming growth factor (TGF)-β1, vascular endothelial growth factor (VEGF), kynurenic acid (KYN), and lower IL-2, IL-4, and interferon (IFN)-γ levels in specific brain regions and suicidal behavior. Unfortunately, most studies are not able to exclude the exact contribution of major depressive disorder (MDD) as a mediator/moderator of the link between inflammatory cytokines abnormalities and suicidal behavior. The association between suicidal patients (both suicide attempters or those with suicidal ideation) and the altered immune system was documented by most studies, but this does not reflect the existence of a specific causal link. Additional studies are needed to clarify the immune pathways underlying suicidal behavior.

The Impact of Nutrition and Intestinal Microbiome on Elderly Depression-A Systematic Review

The aim of this review is to systematically review the evidence whether proper nutrition has a positive impact on the prevention or decline of depressive symptoms among elderly people. In addition, possible connections between nutrition, microbiome, and serotonin molecules and its tryptophan precursor are discussed. The methodology follows the PRISMA guidelines, including the PRISMA flow chart. The authors systematically reviewed peer-review, English-written articles published in Web of Science and PubMed between 2013 and 2018. The findings of six original articles, detected on the set inclusion and exclusion criteria, indicate that there is an association between nutrition and depressive symptoms in the target group, i.e., that proper nutrition has a positive impact on the prevention or reduction of depressive symptoms among elderly people. The findings also reveal that there is a considerable correlation between the intakes of vitamin B and a decrease in the prevalence of depressive symptoms. Furthermore, sufficient nutrient intake of tryptophan appears to be an important factor in terms of nutrition and serotonin levels in the body. The authors consider it important to explore associations between the overall dietary intake and depression since diets are not consumed as individual nutrients. Returning to preventive approaches seems to be a rational way to promote the mental health of seniors. Future studies thus need to include interdisciplinary collaboration: from a good diagnosis of the disease by a psychiatrist, through an analysis of the need for nutrient metabolism by a biochemist to the development of a nutritional plan by a nutritional therapist. The limitations of this review consist in a relatively small number of the studies on this topic, including just few randomized controlled trials, which are a guarantee of efficacy and objectivity in comparison with cross-sectional studies.

Herbal medicine for psychiatric disorders: Psychopharmacology and neuroscience-based nomenclature

Objectives: Herbs are frequently and concurrently used with prescribed drugs by patients worldwide. While clinical trials have found some herbs to be as useful as standard psychiatric drugs, most clinicians are unaware of their pharmacological mechanisms.Methods: We searched English language and other language literature with English abstracts listed in PubMed website, supplemented by additional through Google Scholar's free academic paper abstract website for publications on herbs, focussing on their clinical use in mental disorders, their neurobiology and their pharmacology.Results: A major reason for herbs remaining outside of mainstream psychiatry is that the terminology and concepts in herbal medicine are not familiar to psychiatrists in general. Many publications regarding the use of herbal medicine for psychiatric disorders are deficient in details regarding diagnosis, criteria for response and the neurobiology details compared with publications on standard psychotropic drugs. Nomenclature for herbal medicine is usually confusing and is not conducive to an easy understanding of their mode of action in psychiatric disorders.Conclusions: The recent neuroscience-based nomenclature (NbN) for psychotropics methodology would be a logical application to herbal medicine in facilitating a better understanding of the use of herbal medicine in psychiatry.

Environmental Mechanisms of Neurodevelopmental Toxicity

PURPOSE OF REVIEW

With the incidence of neurodevelopmental disorders on the rise, it is imperative to identify and understand the mechanisms by which environmental contaminants can impact the developing brain and heighten risk. Here, we report on recent findings regarding novel mechanisms of developmental neurotoxicity and highlight chemicals of concern, beyond traditionally defined neurotoxicants.

RECENT FINDINGS

The perinatal window represents a critical and extremely vulnerable period of time during which chemical insult can alter the morphological and functional trajectory of the developing brain. Numerous chemical classes have been associated with alterations in neurodevelopment including metals, solvents, pesticides, and, more recently, endocrine-disrupting compounds. Although mechanisms of neurotoxicity have traditionally been identified as pathways leading to neuronal cell death, neuropathology, or severe neural injury, recent research highlights alternative mechanisms that result in more subtle but consequential changes in the brain and behavior. These emerging areas of interest include neuroendocrine and immune disruption, as well as indirect toxicity via actions on other organs such as the gut and placenta. Understanding of the myriad ways in which the developing brain is vulnerable to chemical exposures has grown tremendously over the past decade. Further progress and implementation in risk assessment is critical to reducing risk of neurodevelopmental disorders.

Pancreatic Cancer-Associated Depression: A Case Report and Review of the Literature

The prevalence of major depressive disorder (MDD) in pancreatic cancer (PC) has been reported up to 7 times higher than the general population. Despite repeated studies that show worse quality of life, survival outcomes, and treatment compliance in cancer patients with depression, baseline antidepressant use ranges from 15% to 27%. A meta-analysis of 6 prospective trials specific to PC estimates that 43% of patients with PC experience depression after diagnosis. This is especially alarming in patients with PC, who may experience a prodrome of symptoms including depression and loss of drive. In fact, this prodrome of symptoms may very well be due to an overexpression of indoleamine 2,3-dioxgenase, an enzyme in the kynurenine pathway that leads to serotonin depletion and the buildup of cytotoxic metabolites in the brain. In this literature review, we outline all previous studies pertinent to PC and depression, as well as the molecular underpinnings that may contribute to states of depression, and report on previous randomized control trials in cancer populations that investigate the use of antidepressants to treat depressive symptoms and improve quality of life both prophylactically and after the onset of major depressive disorder. In addition, we detail a case report outlining the precipitous decline in health in 1 patient with PC and depression.

Access to the CNS: Biomarker Strategies for Dopaminergic Treatments

Despite substantial research carried out over the last decades, it remains difficult to understand the wide range of pharmacological effects of dopaminergic agents. The dopaminergic system is involved in several neurological disorders, such as Parkinson's disease and schizophrenia. This complex system features multiple pathways implicated in emotion and cognition, psychomotor functions and endocrine control through activation of G protein-coupled dopamine receptors. This review focuses on the system-wide effects of dopaminergic agents on the multiple biochemical and endocrine pathways, in particular the biomarkers (i.e., indicators of a pharmacological process) that reflect these effects. Dopaminergic treatments developed over the last decades were found to be associated with numerous biochemical pathways in the brain, including the norepinephrine and the kynurenine pathway. Additionally, they have shown to affect peripheral systems, for example the hypothalamus-pituitary-adrenal (HPA) axis. Dopaminergic agents thus have a complex and broad pharmacological profile, rendering drug development challenging. Considering the complex system-wide pharmacological profile of dopaminergic agents, this review underlines the needs for systems pharmacology studies that include: i) proteomics and metabolomics analysis; ii) longitudinal data evaluation and mathematical modeling; iii) pharmacokinetics-based interpretation of drug effects; iv) simultaneous biomarker evaluation in the brain, the cerebrospinal fluid (CSF) and plasma; and v) specific attention to condition-dependent (e.g., disease) pharmacology. Such approach is considered essential to increase our understanding of central nervous system (CNS) drug effects and substantially improve CNS drug development.

Plasma Metabolites Predict Severity of Depression and Suicidal Ideation in Psychiatric Patients-A Multicenter Pilot Analysis

Evaluating the severity of depression (SOD), especially suicidal ideation (SI), is crucial in the treatment of not only patients with mood disorders but also psychiatric patients in general. SOD has been assessed on interviews such as the Hamilton Rating Scale for Depression (HAMD)-17, and/or self-administered questionnaires such as the Patient Health Questionnaire (PHQ)-9. However, these evaluation systems have relied on a person's subjective information, which sometimes lead to difficulties in clinical settings. To resolve this limitation, a more objective SOD evaluation system is needed. Herein, we collected clinical data including HAMD-17/PHQ-9 and blood plasma of psychiatric patients from three independent clinical centers. We performed metabolome analysis of blood plasma using liquid chromatography mass spectrometry (LC-MS), and 123 metabolites were detected. Interestingly, five plasma metabolites (3-hydroxybutyrate (3HB), betaine, citrate, creatinine, and gamma-aminobutyric acid (GABA)) are commonly associated with SOD in all three independent cohort sets regardless of the presence or absence of medication and diagnostic difference. In addition, we have shown several metabolites are independently associated with sub-symptoms of depression including SI. We successfully created a classification model to discriminate depressive patients with or without SI by machine learning technique. Finally, we produced a pilot algorithm to predict a grade of SI with citrate and kynurenine. The above metabolites may have strongly been associated with the underlying novel biological pathophysiology of SOD. We should explore the biological impact of these metabolites on depressive symptoms by utilizing a cross species study model with human and rodents. The present multicenter pilot study offers a potential utility for measuring blood metabolites as a novel objective tool for not only assessing SOD but also evaluating therapeutic efficacy in clinical practice. In addition, modification of these metabolites by diet and/or medications may be a novel therapeutic target for depression. To clarify these aspects, clinical trials measuring metabolites before/after interventions should be conducted. Larger cohort studies including non-clinical subjects are also warranted to clarify our pilot findings.

Serum IL-4 and IL-10 Levels Correlate with the Symptoms of the Drug-Naive Adolescents with First Episode, Early Onset Schizophrenia

OBJECTIVE

In this study, it was aimed to understand the underlying possible immunopathogenesis of first episode, early onset schizophrenia (EOS) through profiling the T helper 1 (Th₁) cell cytokines TNF-α, IFN-γ, and IL-2, Th₂ cell cytokines IL-4 and IL-10, Th₁₇ cell cytokine IL-17A, and inflammatory cytokine IL-6.

METHODS

The study included a total of 30 children, admitted to child psychiatry outpatient clinic aged between 10 and 17 years of age, who had not received prior therapy and were diagnosed with psychosis according to the Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) as the patient group, and 26 age- and gender-matched children as the control group. Structured psychiatric interviews (K-SADS-PL and PANSS) were conducted with all participants. The BD Cytokine Bead Array Human Th₁/Th₂/Th₁₇ Cytokine Kit is used for the measurement of serum cytokines, for example, IL-2, IL-4, IL-6, IL-10, IL-17A, TNF-α, and IFN-γ.

RESULTS

There was no significant difference between groups in terms of IL-2, IL-4, IL-6, IL-10, IL-17A, TNF-α, and IFN-γ levels (p > 0.05). However, there was a significant correlation between IL-10 and IL-4 with negative symptoms of EOS (r = -0.65, p = 0.02 and r = 0.67, p = 0.02, respectively).

CONCLUSION

IL4 and IL-10 levels have a relationship with negative symptoms of disease. Therefore, this study might suggest that immunological processes might have a role in the disease pathophysiology.

Prevention of unpredictable chronic stress-related phenomena in zebrafish exposed to bromazepam, fluoxetine and nortriptyline

RATIONALE

Several model organisms have been employed to study the impacts of stress on biological systems. Different models of unpredictable chronic stress (UCS) have been established in rodents; however, these protocols are expensive, long-lasting, and require a large physical structure. Our group has recently reported an UCS protocol in zebrafish with several advantages compared to rodent models. We observed that UCS induced behavioral, biochemical, and molecular changes similar to those observed in depressed patients, supporting the translational relevance of the protocol.

OBJECTIVES

Considering that a pharmacological assessment is lacking in this zebrafish model, our aim was to evaluate the effects of anxiolytic (bromazepam) and antidepressant drugs (fluoxetine and nortriptyline) on behavioral (novel tank test), biochemical (whole-body cortisol), and molecular parameters (cox-2, tnf-α, il-6, and il-10 gene expression) in zebrafish subjected to UCS.

RESULTS

We replicated previous data showing that UCS induces behavioral and neuroendocrine alterations in zebrafish, and we show for the first time that anxiolytic and antidepressant drugs are able to prevent such effects. Furthermore, we extended the molecular characterization of the model, revealing that UCS increases expression of the pro-inflammatory markers cox-2 and il-6, which was also prevented by the drugs tested.

CONCLUSIONS

This study reinforces the use of zebrafish as a model organism to study the behavioral and physiological effects of stress. The UCS protocol may also serve as a screening tool for evaluating new drugs that can be used to treat psychiatric disorders with stress-related etiologies.

Role of the Kynurenine Metabolism Pathway in Inflammation-Induced Depression: Preclinical Approaches

Physically ill patients with chronic inflammation often present with symptoms of depression. Our understanding of the pathophysiology of inflammation-associated depression has benefited from preclinical studies on the mechanisms of sickness and clinical studies on the symptoms of sickness and depression that develop in patients treated with immunotherapy. Sickness behavior develops when the immune system is activated by pathogen- or damage-associated molecular patterns. It is a normal biological response to infection and cell injury. It helps the organism to mobilize its immune and metabolic defenses to fight the danger. Depression emerges on the background of sickness when the inflammatory response is too intense and long lasting or the resolution process is deficient. The transition from sickness to depression is mediated by activation of the kynurenine metabolism pathway that leads to the formation of neurotoxic kynurenine metabolites including quinolinic acid, an agonist of N-methyl-D-aspartate receptors. The neuroimmune processes and molecular factors that have been identified in the studies of inflammation-associated depression represent potential new targets for the development of innovative therapies for the treatment of major depressive disorders.

Glial cells as key players in schizophrenia pathology: recent insights and concepts of therapy

The past decade has witnessed an explosion of knowledge on the impact of glia for the neurobiological foundation of schizophrenia. A plethora of studies have shown structural and functional abnormalities in all three types of glial cells. There is convincing evidence of reduced numbers of oligodendrocytes, impaired cell maturation and altered gene expression of myelin/oligodendrocyte-related genes that may in part explain white matter abnormalities and disturbed inter- and intra-hemispheric connectivity, which are characteristic signs of schizophrenia. Earlier reports of astrogliosis could not be confirmed by later studies, although the expression of a variety of astrocyte-related genes is abnormal in psychosis. Since astrocytes play a key role in the synaptic metabolism of glutamate, GABA, monoamines and purines, astrocyte dysfunction may contribute to certain aspects of disturbed neurotransmission in schizophrenia. Finally, increased densities of microglial cells and aberrant expression of microglia-related surface markers in schizophrenia suggest that immunological/inflammatory factors are of considerable relevance for the pathophysiology of psychosis. This review describes current evidence for the multifaceted role of glial cells in schizophrenia and discusses efforts to develop glia-directed therapies for the treatment of the disease.

Antidepressant-like effect of celecoxib piroxicam in rat models of depression

Beyond the current hypothesis of depression, several new biological substrates have been proposed for this disorder. The present study investigated whether the anti-inflammatory drugs celecoxib and piroxicam have antidepressant activity in animal models of depression. After acute administration, we observed antidepressant-like effects of celecoxib (10 mg/kg) and piroxicam (10 mg/kg) in the modified forced swim test in rats. Piroxicam increased serotonin and norepinephrine levels in the hippocampus. Prolonged (21-day) treatment with celecoxib (10 mg/kg) and piroxicam (10 mg/kg) rescued sucrose preference in a chronic mild stress model of depression. Additionally, the chronic mild stress-induced reduction of hippocampal glutathione was prevented by treatment with celecoxib and piroxicam. Superoxide dismutase in the hippocampus was increased after chronic mild stress compared with the non-stressed saline group. The non-stressed celecoxib and piroxicam groups and stressed piroxicam group exhibited an increase in hippocampal superoxide dismutase activity compared with the stressed saline group. Lipid hydroperoxide was increased in the stressed group treated with vehicle and non-stressed group treated with imipramine but not in the stressed groups treated with celecoxib and piroxicam. These results suggest that the antidepressant-like effects of anti-inflammatory drugs might be attributable to enhanced antioxidant defenses and attenuated oxidative stress in the hippocampus.

Inflammation and the two-hit hypothesis of schizophrenia

The high societal and individual cost of schizophrenia necessitates finding better, more effective treatment, diagnosis, and prevention strategies. One of the obstacles in this endeavor is the diverse set of etiologies that comprises schizophrenia. A substantial body of evidence has grown over the last few decades to suggest that schizophrenia is a heterogeneous syndrome with overlapping symptoms and etiologies. At the same time, an increasing number of clinical, epidemiological, and experimental studies have shown links between schizophrenia and inflammatory conditions. In this review, we analyze the literature on inflammation and schizophrenia, with a particular focus on comorbidity, biomarkers, and environmental insults. We then identify several mechanisms by which inflammation could influence the development of schizophrenia via the two-hit hypothesis. Lastly, we note the relevance of these findings to clinical applications in the diagnosis, prevention, and treatment of schizophrenia.

Susceptibility genes are enriched in those of the herpes simplex virus 1/host interactome in psychiatric and neurological disorders

Herpes simplex virus 1 (HSV-1) can promote beta-amyloid deposition and tau phosphorylation, demyelination or cognitive deficits relevant to Alzheimer's disease or multiple sclerosis and to many neuropsychiatric disorders with which it has been implicated. A seroprevalence much higher than disease incidence has called into question any primary causal role. However, as also the case with risk-promoting polymorphisms (also present in control populations), any causal effects are likely to be conditional. During its life cycle, the virus binds to many proteins and modifies the expression of multiple genes creating a host/pathogen interactome involving 1347 host genes. This data set is heavily enriched in the susceptibility genes for multiple sclerosis (P = 1.3E-99) > Alzheimer's disease > schizophrenia > Parkinsonism > depression > bipolar disorder > childhood obesity > chronic fatigue > autism > and anorexia (P = 0.047) but not attention deficit hyperactivity disorder, a relationship maintained for genome-wide association study data sets in multiple sclerosis and Alzheimer's disease. Overlapping susceptibility gene/interactome data sets disrupt signalling networks relevant to each disease, suggesting that disease susceptibility genes may filter the attentions of the pathogen towards particular pathways and pathologies. In this way, the same pathogen could contribute to multiple diseases in a gene-dependent manner and condition the risk-promoting effects of the genes whose function it disrupts.

Evidence for a neuroinflammatory mechanism in delayed effects of early life adversity in rats: relationship to cortical NMDA receptor expression

Postnatal maternal separation in rats causes a reduction of GABAergic parvalbumin-containing interneurons in the prefrontal cortex that first occurs in adolescence. This parvalbumin loss can be prevented by pre-adolescent treatment with a non-steroidal anti-inflammatory drug that also protects against excitotoxicity. Therefore, the neuropsychiatric disorders associated with early life adversity and interneuron dysfunction may involve neuroinflammatory processes and/or aberrant glutamatergic activity. Here, we aimed to determine whether delayed parvalbumin loss after maternal separation was due to inflammatory activity, and whether central administration of the anti-inflammatory cytokine interleukin (IL)-10 could protect against such loss. We also investigated the effects of maternal separation and IL-10 treatment on cortical NMDA receptor expression. Male rat pups were isolated for 4h/day between postnatal days 2-20. IL-10 was administered intracerebroventricularly through an indwelling cannula between P30 and 38. Adolescent prefrontal cortices were analyzed using Western blotting and immunohistochemistry for parvalbumin and NMDA NR2A subunit expression. We demonstrate that central IL-10 administration during pre-adolescence protects maternally separated animals from parvalbumin loss in adolescence. Linear regression analyses revealed that increased circulating levels of the pro-inflammatory cytokines IL-1β and IL-6 predicted lowered parvalbumin levels in maternally separated adolescents. Maternal separation also increases cortical expression of the NR2A NMDA receptor subunit in adolescence, which is prevented by IL-10 treatment. These data suggest that inflammatory damage to parvalbumin interneurons may occur via aberrant glutamatergic activity in the prefrontal cortex. Our findings provide a novel interactive mechanism between inflammation and neural dysfunction that helps explain deleterious effects of early life adversity on prefrontal cortex interneurons.

Explorando o componente inflamatório da esquizofrenia

A esquizofrenia é uma doença heterogênea caracterizada por um conjunto de manifestações clínicas. Um grande número de estudos ao longo dos últimos 20 anos apontou para anormalidades no sistema imune em pacientes que sofrem dessa condição. Em adição, tem sido mostrado que a psicose e a disfunção cognitiva associadas com a esquizofrenia estão ligadas a doenças autoimunes. Aqui, revisamos a evidência que sugere que um status pró-inflamatório do sistema imune induz sintomas psicopatológicos e pode estar envolvido na fisiopatologia dessa principal doença mental. Também propomos que futuros estudos pré-clínicos e clínicos deveriam levar em conta tais causas predefinidas e o status do componente inflamatório. Estratificação de pacientes e estratégias de medicina personalizadas baseadas no direcionamento ao componente inflamatório da doença poderiam ajudar na redução de sintomas e da progressão da doença. Por fim, isso poderia levar a novos conceitos na identificação de alvos moleculares em esquizofrenia e estratégias de descoberta de drogas.

Effect of celecoxib add-on treatment on symptoms and serum IL-6 concentrations in patients with major depressive disorder: randomized double-blind placebo-controlled study

BACKGROUND

It has been proposed that the mechanism of the antidepressant effect of celecoxib is linked to its anti-inflammatory action and particularly its inhibitory effect on pro-inflammatory cytokines (e.g. interleukin-6(IL-6)). We measured changes in serum IL-6 concentrations and depressive symptoms following administration of celecoxib in patients with major depressive disorder (MDD).

METHODS

In a randomized double-blind placebo-controlled study, 40 patients with MDD and Hamilton Depression Rating Scale-17 items (Ham-D) score ≥18 were randomly assigned to either celecoxib (200mg twice daily) or placebo in addition to sertraline (200mg/day) for 6 weeks. Outcome measures were serum IL-6 concentrations at baseline and week 6, and Ham-D scores at baseline and weeks 1, 2, 4, and 6.

RESULTS

The celecoxib group showed significantly greater reduction in serum IL-6 concentrations (mean difference (95%CI)=0.42(0.30 to 0.55) pg/ml, t(35)=6.727, P<0.001) as well as Ham-D scores (mean difference (95%CI)=3.35(1.08 to 5.61), t(38)=2.99, P=0.005) than the placebo group. The patients in the celecoxib group experienced more response (95%) and remission (35%) than the placebo group (50% and 5%, P=0.003 and 0.04 respectively). Baseline serum IL-6 levels were significantly correlated with baseline Ham-D scores (r=0.378, P=0.016). Significant correlation was observed between reduction of Ham-D scores and reduction of serum IL-6 levels at week 6 (r=0.673, P<0.001).

LIMITATIONS

We did not measure other inflammatory biomarkers.

CONCLUSIONS

We showed that the antidepressant activity of celecoxib might be linked to its capability of reducing IL-6 concentrations. Moreover, supporting previous studies we showed that celecoxib is both safe and effective as an adjunctive antidepressant (Registration number: IRCT138903124090N1).

Bridging the gap between the immune and glutamate hypotheses of schizophrenia and major depression: Potential role of glial NMDA receptor modulators and impaired blood-brain barrier integrity

OBJECTIVES

Previous studies have suggested that the pathogenesis of schizophrenia and major depression involves an altered peripheral immune system. It is not clear, however, whether such changes are associated with corresponding neuroinflammatory responses and disturbances of neurotransmission.

METHODS

This paper reviews the current state of knowledge about the involvement of immune alterations in schizophrenia and major depression and a possible link to disturbances of glutamatergic transmission.

RESULTS

Inflammatory endogenous modulators of the NMDA receptor, the kynurenine pathway metabolites, are potential candidates for such a link. Studies of the blood and cerebrospinal fluid have suggested a schizophrenia-related upregulation of the NMDA receptor antagonist kynurenic acid in astrocytes, analogous to the ketamine psychosis model. Conversely, it has been proposed that there is depression-related microglial synthesis of the NMDA receptor agonist quinolinic acid, which is consistent with the observation that ketamine has therapeutic effects in major depression. Few publications have studied NMDA receptor modulating kynurenines in the brain, however.

CONCLUSIONS

Future research on the cerebral cell-type specific distribution of kynurenine metabolites and their brain-regional concentration imbalances will be required to connect peripheral immune changes, the hypotheses of blood-brain barrier dysfunction and glial pathology with concepts of altered neurotransmission in schizophrenia and major depression.

Analysis of lead toxicity in human cells

BACKGROUND

Lead is a metal with many recognized adverse health side effects, and yet the molecular processes underlying lead toxicity are still poorly understood. Quantifying the injurious effects of lead is also difficult because of the diagnostic limitations that exist when analyzing human blood and urine specimens for lead toxicity.

RESULTS

We analyzed the deleterious impact of lead on human cells by measuring its effects on cytokine production and gene expression in peripheral blood mononuclear cells. Lead activates the secretion of the chemokine IL-8 and impacts mitogen-dependent activation by increasing the secretion of the proinflammatory cytokines IL-6 and TNF-α and of the chemokines IL-8 and MIP1-α in the presence of phytohemagglutinin. The recorded changes in gene expression affected major cellular functions, including metallothionein expression, and the expression of cellular metabolic enzymes and protein kinase activity. The expression of 31 genes remained elevated after the removal of lead from the testing medium thereby allowing for the measurement of adverse health effects of lead poisoning. These included thirteen metallothionein transcripts, three endothelial receptor B transcripts and a number of transcripts which encode cellular metabolic enzymes. Cellular responses to lead correlated with blood lead levels and were significantly altered in individuals with higher lead content resultantly affecting the nervous system, the negative regulation of transcription and the induction of apoptosis. In addition, we identified changes in gene expression in individuals with elevated zinc protoporphyrin blood levels and found that genes regulating the transmission of nerve impulses were affected in these individuals. The affected pathways were G-protein mediated signaling, gap junction signaling, synaptic long-term potentiation, neuropathic pain signaling as well as CREB signaling in neurons. Cellular responses to lead were altered in subjects with high zinc protoporphyrin blood levels.

CONCLUSIONS

The results of our study defined specific changes in gene and protein expression in response to lead challenges and determined the injurious effects of exposures to lead on a cellular level. This information can be used for documenting the health effects of exposures to lead which will facilitate identifying and monitoring efficacious treatments for lead-related maladies.

Cytokines in schizophrenia: possible role of anti-inflammatory medications in clinical and preclinical stages

AIMS

In this paper, we review the literature on the efficacy of anti-inflammatory agents as neuroprotectors in clinical and preclinical stages of schizophrenia.

METHOD

A synthetic and integrative approach was applied to review studies stemming from epidemiology, phenomenology, cognition, genetics and neuroimaging data. We provide conclusions and future directions of research on early-onset schizophrenia.

RESULTS

Abnormal inflammatory activation has been demonstrated in schizophrenia. Increases or imbalances in cytokines before birth or during childhood may impact neurodevelopment and produce vulnerability to schizophrenia. The specificity of inflammatory abnormalities in psychiatric disorders is controversial. Similar increases in pro-inflammatory cytokines have been described in other disorders, especially mood and anxiety disorders. One of the most important challenges at this point is the understanding of neurobiological correlates of prodromal stages of schizophrenia.

CONCLUSION

Although future research should investigate the exact role of different cytokines in pathophysiology of schizophrenia, these mediators emerge as promising molecular targets to its prevention and treatment.

Quinolinic Acid, an endogenous molecule combining excitotoxicity, oxidative stress and other toxic mechanisms

Quinolinic acid (QUIN), an endogenous metabolite of the kynurenine pathway, is involved in several neurological disorders, including Huntington’s disease, Alzheimer’s disease, schizophrenia, HIV associated dementia (HAD) etc. QUIN toxicity involves several mechanisms which trigger various metabolic pathways and transcription factors. The primary mechanism exerted by this excitotoxin in the central nervous system (CNS) has been largely related with the overactivation of N-methyl-D-aspartate receptors and increased cytosolic Ca²⁺ concentrations, followed by mitochondrial dysfunction, cytochrome c release, ATP exhaustion, free radical formation and oxidative damage. As a result, this toxic pattern is responsible for selective loss of middle size striatal spiny GABAergic neurons and motor alterations in lesioned animals. This toxin has recently gained attention in biomedical research as, in addition to its proven excitotoxic profile, a considerable amount of evidence suggests that oxidative stress and energetic disturbances are major constituents of its toxic pattern in the CNS. Hence, this profile has changed our perception of how QUIN-related disorders combine different toxic mechanisms resulting in brain damage. This review will focus on the description and integration of recent evidence supporting old and suggesting new mechanisms to explain QUIN toxicity.

Sub-chronic dietary tryptophan depletion--an animal model of depression with improved face and good construct validity

Sub-chronic tryptophan depletion (SCTD) is proposed as an animal model for depression. Aims were to test the hypothesis and optimise the time of SCTD-induced depression-related behaviour and associated biochemical changes. Sprague Dawley rats were treated with a low tryptophan (TRP) containing diet for 0, 7 or 14 days. Peripheral and central neurochemical markers were measured. SCTD-induced depression-related behaviour was assessed by the forced swim test (FST). Model sensitivity to antidepressants was tested by concomitant treatment with paroxetine. SCTD-induced significant reductions in weight gain and measures of peripheral and central TRP. Corticosterone, aldosterone and kynurenine (K), increased whilst kynurenic acid (KA), an NMDA antagonist decreased. 5-HT(2) receptor binding Bmax was enhanced but was reversed by paroxetine. Corticosterone and aldosterone were significantly negatively-correlated to weight gain. SCTD increased floating time and reduced swimming time in the FST but were reversed by paroxetine. Aldosterone was increased at 7 and 14 days, whereas other changes maximised at 14 days. Aldosterone may be an early marker or causal link for depression development. Increased corticosterone and brain tissue 5-HT-receptor density may be correlates of depressive behaviour. Consequential increases in NMDA signalling through increased K/KA ratios suggest the model may be useful for testing novel antidepressants.

A comprehensive network and pathway analysis of candidate genes in major depressive disorder

BACKGROUND

Numerous genetic and genomic datasets related to complex diseases have been made available during the last decade. It is now a great challenge to assess such heterogeneous datasets to prioritize disease genes and perform follow up functional analysis and validation. Among complex disease studies, psychiatric disorders such as major depressive disorder (MDD) are especially in need of robust integrative analysis because these diseases are more complex than others, with weak genetic factors at various levels, including genetic markers, transcription (gene expression), epigenetics (methylation), protein, pathways and networks.

RESULTS

In this study, we proposed a comprehensive analysis framework at the systems level and demonstrated it in MDD using a set of candidate genes that have recently been prioritized based on multiple lines of evidence including association, linkage, gene expression (both human and animal studies), regulatory pathway, and literature search. In the network analysis, we explored the topological characteristics of these genes in the context of the human interactome and compared them with two other complex diseases. The network topological features indicated that MDD is similar to schizophrenia compared to cancer. In the functional analysis, we performed the gene set enrichment analysis for both Gene Ontology categories and canonical pathways. Moreover, we proposed a unique pathway crosstalk approach to examine the dynamic interactions among biological pathways. Our pathway enrichment and crosstalk analyses revealed two unique pathway interaction modules that were significantly enriched with MDD genes. These two modules are neuro-transmission and immune system related, supporting the neuropathology hypothesis of MDD. Finally, we constructed a MDD-specific subnetwork, which recruited novel candidate genes with association signals from a major MDD GWAS dataset.

CONCLUSIONS

This study is the first systematic network and pathway analysis of candidate genes in MDD, providing abundant important information about gene interaction and regulation in a major psychiatric disease. The results suggest potential functional components underlying the molecular mechanisms of MDD and, thus, facilitate generation of novel hypotheses in this disease. The systems biology based strategy in this study can be applied to many other complex diseases.

Schizophrenia as a disorder of too little dopamine: implications for symptoms and treatment

Antipsychotics represent the first effective therapy for schizophrenia, with their benefits linked to dopamine D2 blockade. Schizophrenia was soon identified as a hyperdopaminergic disorder, and antipsychotics proved to be reasonably effective in controlling positive symptoms. However, over the years, schizophrenia has been reconceptualized more broadly, now defined as a heterogeneous disorder with multiple symptom domains. Negative and cognitive features, not particularly responsive to antipsychotic therapy, have taken on increased importance--current thinking suggests that these domains predate the onset of positive symptoms and are more closely tied to functional outcome. That they are better understood in the context of decreased dopamine activity suggests that schizophrenia may fundamentally represent a hypodopaminergic disorder. This shift in thinking has important theoretical implications from the standpoint of etiology and pathophysiology, but also clinically in terms of treatment and drug development.

Toxoplasma gondii antibody titers and history of suicide attempts in patients with schizophrenia

Toxoplasma gondii (T. gondii) a widespread neurotropic parasite, has been previously associated with schizophrenia and more recently with suicidal behavior. However, no previous study has examined the association of T. gondii with suicidal behavior in schizophrenia patients. 950 individuals diagnosed with schizophrenia by SCID were recruited from the Munich area of Germany. Solid-enzyme immunoassay methods were used to measure IgG plasma antibodies to T. gondii, other neurotropic pathogens and gliadin. Logistic regression models were developed to analyze the association of T. gondii seropositivity or serointensity with history of suicidal behavior. In those younger than the median age of the sample, 38, T. gondii serointensity was associated with history of suicidal behavior (p = 0.02), while in the older patients the relationship was not significant (p = 0.21). Seropositivity was also associated with history of suicide attempt in younger patients, odds ratio 1.59 (95% CI 1.06 to 2.40), p = 0.03. Seropositivity for CMV (p = 0.22), HSV-1 (p = 0.36) and gliadin (p = 0.92) was not related to history of suicide attempt in the entire sample or any age subgroup. T. gondii serology might become, with interaction with vulnerability genes, a candidate biomarker for a subgroup of schizophrenia patients prone to attempting suicide.

Inflammatory processes in schizophrenia: a promising neuroimmunological target for the treatment of negative/cognitive symptoms and beyond

Emerging evidence indicates that schizophrenia is associated with activated peripheral and central inflammatory responses. Such inflammatory processes seem to be influenced by a number of environmental and genetic predisposition factors, and they may critically depend on and contribute to the progressive nature of schizophrenic disease. There is also appreciable evidence to suggest that activated inflammatory responses can undermine disease-relevant affective, emotional, social, and cognitive functions, so that inflammatory processes may be particularly relevant for the precipitation of negative and cognitive symptoms of schizophrenia. Recent clinical trials of anti-inflammatory pharmacotherapy in this disorder provide promising results by showing superior beneficial treatment effects when standard antipsychotic drugs are co-administered with anti-inflammatory compounds, as compared with treatment outcomes using antipsychotic drugs alone. Given the limited efficacy of currently available antipsychotic drugs to ameliorate negative and cognitive symptoms, the further exploration of inflammatory mechanisms and anti-inflammatory strategies may open fruitful new avenues for improved treatment of symptoms undermining affective, emotional, social and cognitive functions pertinent to schizophrenic disease.

In animal models, psychosocial stress-induced (neuro)inflammation, apoptosis and reduced neurogenesis are associated to the onset of depression

Recently, the inflammatory and neurodegenerative (I&ND) hypothesis of depression was formulated (Maes et al., 2009), i.e. the neurodegeneration and reduced neurogenesis that characterize depression are caused by inflammation, cell-mediated immune activation and their long-term sequels. The aim of this paper is to review the body of evidence that external stressors may induce (neuro)inflammation, neurodegeneration and reduced neurogenesis; and that antidepressive treatments may impact on these pathways. The chronic mild stress (CMS) and learned helplessness (LH) models show that depression-like behaviors are accompanied by peripheral and central inflammation, neuronal cell damage, decreased neurogenesis and apoptosis in the hippocampus. External stress-induced depression-like behaviors are associated with a) increased interleukin-(IL)1β, tumor necrosis factor-α, IL-6, nuclear factor κB, cyclooxygenase-2, expression of Toll-like receptors and lipid peroxidation; b) antineurogenic effects and reduced brain-derived neurotrophic factor (BDNF) levels; and c) apoptosis with reduced levels of Bcl-2 and BAG1 (Bcl-2 associated athanogene 1), and increased levels of caspase-3. Stress-induced inflammation, e.g. increased IL-1β, but not reduced neurogenesis, is sufficient to cause depression. Antidepressants a) reduce peripheral and central inflammatory pathways by decreasing IL-1β, TNFα and IL-6 levels; b) stimulate neuronal differentiation, synaptic plasticity, axonal growth and regeneration through stimulatory effects on the expression of different neurotrophic factors, e.g. trkB, the receptor for brain-derived neurotrophic factor; and c) attenuate apoptotic pathways by activating Bcl-2 and Bcl-xl proteins, and suppressing caspase-3. It is concluded that external stressors may provoke depression-like behaviors through activation of inflammatory, oxidative, apoptotic and antineurogenic mechanisms. The clinical efficacity of antidepressants may be ascribed to their ability to reverse these different pathways.

Interferon-gamma-inducible kynurenines/pteridines inflammation cascade: implications for aging and aging-associated psychiatric and medical disorders

This review of literature and our data suggests that up-regulated production of interferon-gamma (IFNG) in periphery and brain triggers a merger of tryptophan (TRY)-kynurenine (KYN) and guanine-tetrahydrobiopterin (BH4) metabolic pathways into inflammation cascade involved in aging and aging-associated medical and psychiatric disorders (AAMPD) (metabolic syndrome, depression, vascular cognitive impairment). IFNG-inducible KYN/pteridines inflammation cascade is characterized by up-regulation of nitric oxide synthase (NOS) activity (induced by KYN) and decreased formation of NOS cofactor, BH4, that results in uncoupling of NOS that shifting arginine from NO to superoxide anion production. Superoxide anion and free radicals among KYN derivatives trigger phospholipase A2-arachidonic acid cascade associated with AAMPD. IFNG-induced up-regulation of indoleamine 2,3-dioxygenase (IDO), rate-limiting enzyme of TRY-KYN pathway, decreases TRY conversion into serotonin (substrate of antidepressant effect) and increases production of KYN associated with diabetes [xanthurenic acid (XA)], anxiety (KYN), psychoses and cognitive impairment (kynurenic acid). IFNG-inducible KYN/pteridines inflammation cascade is impacted by IFNG (+874) T/A genotypes, encoding cytokine production. In addition to literature data on KYN/TRY ratio (IDO activity index), we observe neopterin levels (index of activity of rate-limiting enzyme of guanine-BH4 pathway) to be higher in carriers of high (T) than of low (A) producers alleles; and to correlate with AAMPD markers (e.g., insulin resistance, body mass index, mortality risk), and with IFN-alpha-induced depression in hepatitis C patients. IFNG-inducible cascade is influenced by environmental factors (e.g., vitamin B6 deficiency increases XA formation) and by pharmacological agents; and might offer new approaches for anti-aging and anti-AAMPD interventions.

Immune activation by casein dietary antigens in bipolar disorder

OBJECTIVES

  Inflammation and other immune processes are increasingly linked to psychiatric diseases. Antigenic triggers specific to bipolar disorder are not yet defined. We tested whether antibodies to bovine milk caseins were associated with bipolar disorder, and whether patients recognized different epitopes of the casein protein than control individuals.

METHODS

  Anti-bovine casein immunoglobulin G (IgG) levels were measured with solid-phase immunoassays in 75 individuals with bipolar disorder and 65 controls. Epitope recognition was evaluated in immunoassays by cross neutralization with anti-bovine casein polyclonal antibodies of defined reactivity. Group-specific reactivity and associations with symptom severity scores were detected with age-, gender-, and race-controlled regression models.

RESULTS

  Individuals with bipolar disorder had significantly elevated anti-casein IgG (t-test, p ≤0.001) compared to controls. Casein IgG seropositivity conferred odds ratios of 3.97 for bipolar disorder [n=75, 95% confidence interval (CI): 1.31-12.08, p ≤0.015], 5.26 for the bipolar I subtype (n=56, 95% CI: 1.66-16.64, p ≤0.005), and 3.98 for bipolar disorder with psychosis (n=54, 95% CI: 1.32-12.00, p ≤0.014). Lithium and/or antipsychotic medication did not significantly affect anti-casein IgG levels. Casein IgG measures correlated with severity of manic (R(2) =0.15, 95% CI: 0.05-0.24, p ≤0.02) but not depressive symptoms. Unlike controls, sera from individuals with bipolar disorder did not inhibit binding of casein-reactive animal sera (t-test/χ(2) , p ≤0.0001).

CONCLUSIONS

  Anti-casein IgG associations with bipolar I diagnoses, psychotic symptom history, and mania severity scores suggest that casein-related immune activation may relate to the psychosis and mania components of this mood disorder. Case-control differences in epitope recognition implicate disease-related alterations in how the casein molecule is digested and/or how resulting casein-derived structures are rendered immunogenic.