Cytokines and depression: the need for a new paradigm

Looking Back to Move Forward: Research in Stress, Behavior, and Immune Function

BACKGROUND

From the original studies investigating the effects of adrenal gland secretion to modern high-throughput multidimensional analyses, stress research has been a topic of scientific interest spanning just over a century.

SUMMARY

The objective of this review was to provide historical context for influential discoveries, surprising findings, and preclinical models in stress-related neuroimmune research. Furthermore, we summarize this work and present a current understanding of the stress pathways and their effects on the immune system and behavior. We focus on recent work demonstrating stress-induced immune changes within the brain and highlight studies investigating stress effects on microglia. Lastly, we conclude with potential areas for future investigation concerning microglia heterogeneity, bone marrow niches, and sex differences.

KEY MESSAGES

Stress is a phenomenon that ties together not only the central and peripheral nervous system, but the immune system as well. The cumulative effects of stress can enhance or suppress immune function, based on the intensity and duration of the stressor. These stress-induced immune alterations are associated with neurobiological changes, including structural remodeling of neurons and decreased neurogenesis, and these contribute to the development of behavioral and cognitive deficits. As such, research in this field has revealed important insights into neuroimmune communication as well as molecular and cellular mediators of complex behaviors relevant to psychiatric disorders.

Endoplasmic reticulum stress, autophagy, neuroinflammation, and sigma 1 receptors as contributors to depression and its treatment

The etiological factors contributing to depression and other neuropsychiatric disorders are largely undefined. Endoplasmic reticulum stress pathways and autophagy are well-defined mechanisms that play critical functions in recognizing and resolving cellular stress and are possible targets for the pathophysiology and treatment of psychiatric and neurologic illnesses. An increasing number of studies indicate the involvement of endoplasmic reticulum stress and autophagy in the control of neuroinflammation, a contributing factor to multiple neuropsychiatric illnesses. Initial inflammatory triggers induce endoplasmic reticulum stress, leading to neuroinflammatory responses. Subsequently, induction of autophagy by neurosteroids and other signaling pathways that converge on autophagy induction are thought to participate in resolving neuroinflammation. The aim of this review is to summarize our current understanding of the molecular mechanisms governing the induction of endoplasmic reticulum stress, autophagy, and neuroinflammation in the central nervous system. Studies focused on innate immune factors, including neurosteroids with anti-inflammatory roles will be reviewed. In the context of depression, animal models that led to our current understanding of molecular mechanisms underlying depression will be highlighted, including the roles of sigma 1 receptors and pharmacological agents that dampen endoplasmic reticulum stress and associated neuroinflammation.

Common protein networks for various drug regimens of major depression are associated with complement and immunity

BACKGROUND

Major depressive disorder (MDD) can present a variety of clinical presentations and has high inter-individual heterogeneity. Multiple studies have suggested various subtype models related to symptoms, etiology, sex, and treatment response. Employing different regimens is common when treating MDD, and identifying effective therapeutics requires time. Frequent treatment attempts and failures can lead to a diagnosis of treatment resistance, and the heterogeneity of treatment responses among individuals makes it difficult to understand and interpret the biological mechanisms underlying MDD.

AIM

This study explored the differentially expressed proteins and commonly altered protein networks across drug treatments by comparing the serum proteomes of patients with MDD treated with drug regimens (T-MDD, n = 20) and untreated patients (NT-MDD, n = 20).

METHODS

Differentially expressed proteins were profiled in non-drug-treated and drug-treated patients with depression using liquid chromatography-mass spectrometry. The common protein networks affected by different medications were studied.

RESULTS

Of the proteins profiled, 12 were significantly differentially expressed between the T-MDD and NT-MDD groups. Commonly altered proteins and networks of various drug treatments for depression were related to the complement system and immunity.

CONCLUSIONS

Our results provide information on common biological changes across different pharmacological treatments employed for depression and provide an alternative perspective for improving our understanding of the biological mechanisms of drug response in MDD with great heterogeneity in the background of the disease.

Changes in tryptophan breakdown associated with response to multimodal treatment in depression

Background

Research on depression showed that dysregulations in tryptophan (TRP), kynurenine (KYN), and its KYN pathway metabolites are key aspects in the development and maintenance of depressive symptoms. In our previous reports, we described sex-specific changes in TRP breakdown as well as changes in KYN and KYN/TRP in association with treatment response and inflammatory and metabolic parameters. However, results of treatment effects on KYN pathway metabolites as well as how pathway changes are related to treatment response remain sparse.

Objective

We investigated potential changes of KYN and KYN pathway metabolites in association with therapeutic response of individuals with depression during a six-week multimodal psychiatric rehabilitation program.

Methods

87 participants were divided into treatment responders and non-responders (48 responders, 39 non-responders; 38 male, 49 female; M age = 51.09; SD age = 7.70) using scores of psychological questionnaires. KYN pathway metabolites serum concentrations as well as their ratios were collected using high performance liquid chromatography. Changes over time (time of admission (t1) vs. time of discharge (t2)) were calculated using repeated measure analyses of (co)variance.

Results

Non-responders exhibited higher levels of 3-Hydroxyanthralinic acid (3-HAA), nicotinic acid (NA), and 3-HAA/KYN, independently of measurement time. NA levels decreased, while 3-HAA levels increased over time in both groups, independently of treatment response. 3-HK/KYN levels decreased, while KYN levels increased in non-responders, but not in responders over time.

Discussion

The results indicate that some compounds of the KYN pathway metabolites can be altered through multimodal long-term interventions in association with treatment response. Especially the pathway degrading KYN further down to 3-HAA and 3-HK/KYN might be decisive for treatment response in depression.

Exploring environmental exposomes and the gut-brain nexus: Unveiling the impact of pesticide exposure

This review delves into the escalating concern of environmental pollutants and their profound impact on human health in the context of the modern surge in global diseases. The utilisation of chemicals in food production, which results in residues in food, has emerged as a major concern nowadays. By exploring the intricate relationship between environmental pollutants and gut microbiota, the study reveals a dynamic bidirectional interplay, as modifying microbiota profile influences metabolic pathways and subsequent brain functions. This review will first provide an overview of potential exposomes and their effect to gut health. This paper is then emphasis the connection of gut brain function by analysing microbiome markers with neurotoxicity responses. We then take pesticide as example of exposome to elucidate their influence to biomarkers biosynthesis pathways and subsequent brain functions. The interconnection between neuroendocrine and neuromodulators elements and the gut-brain axis emerges as a pivotal factor in regulating mental health and brain development. Thus, manipulation of gut microbiota function at the onset of stress may offer a potential avenue for the prevention and treatment for mental disorder and other neurodegenerative illness.

Discovery and validation of protein biomarkers for monitoring the effectiveness of drug treatment for major depressive disorder

Major depressive disorder (MDD) has a high prevalence worldwide. Although the economic burden of depression increases annually, the proportion of patients with MDD receiving treatment did not increase between 2010 and 2018, suggesting an unmet treatment need. The burden of long-term treatment for depression is borne by patients. In this context, biomarkers associated with drug-treatment responses can be used as reference indicators to reduce unnecessary treatment and costs. Changes in biomolecules in response to drug treatment for depression and drug-treatment response markers have been studied extensively. The Hamilton Depression Rating Scale (HAM-D) is mainly used as an indicator of response and remission; however, it is difficult to determine whether the medication contributes to recovery when evaluating the effect of drug treatment for depression based on this assessment. Therefore, it is necessary to monitor the effect of medication compared to normal health conditions. Here, serum protein levels were compared using liquid chromatography-tandem mass spectrometry among a group of patients with depression who did not receive medication, a group of patients receiving medication, and a control group. Eight selected biomarkers, including Apolipoproteins A-I, Complement factor H, Complement C5, Complement C1q subcomponent subunit B, Alpha-2-HS-glycoprotein, Complement C1q subcomponent subunit C, Vitamin D-binding protein and Corticosteroid-binding globulin were distinguished between disease states, and protein levels in the drug-treated group were similar to those in the control group. These markers can be used to monitor the effectiveness of drug treatment.

A review of cytokine-based pathophysiology of Long COVID symptoms

The Long COVID/Post Acute Sequelae of COVID-19 (PASC) group includes patients with initial mild-to-moderate symptoms during the acute phase of the illness, in whom recovery is prolonged, or new symptoms are developed over months. Here, we propose a description of the pathophysiology of the Long COVID presentation based on inflammatory cytokine cascades and the p38 MAP kinase signaling pathways that regulate cytokine production. In this model, the SARS-CoV-2 viral infection is hypothesized to trigger a dysregulated peripheral immune system activation with subsequent cytokine release. Chronic low-grade inflammation leads to dysregulated brain microglia with an exaggerated release of central cytokines, producing neuroinflammation. Immunothrombosis linked to chronic inflammation with microclot formation leads to decreased tissue perfusion and ischemia. Intermittent fatigue, Post Exertional Malaise (PEM), CNS symptoms with "brain fog," arthralgias, paresthesias, dysautonomia, and GI and ophthalmic problems can consequently arise as result of the elevated peripheral and central cytokines. There are abundant similarities between symptoms in Long COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). DNA polymorphisms and viral-induced epigenetic changes to cytokine gene expression may lead to chronic inflammation in Long COVID patients, predisposing some to develop autoimmunity, which may be the gateway to ME/CFS.

Dopamine Transmission Imbalance in Neuroinflammation: Perspectives on Long-Term COVID-19

Dopamine (DA) is a key neurotransmitter in the basal ganglia, implicated in the control of movement and motivation. Alteration of DA levels is central in Parkinson’s disease (PD), a common neurodegenerative disorder characterized by motor and non-motor manifestations and deposition of alpha-synuclein (α-syn) aggregates. Previous studies have hypothesized a link between PD and viral infections. Indeed, different cases of parkinsonism have been reported following COVID-19. However, whether SARS-CoV-2 may trigger a neurodegenerative process is still a matter of debate. Interestingly, evidence of brain inflammation has been described in postmortem samples of patients infected by SARS-CoV-2, which suggests immune-mediated mechanisms triggering the neurological sequelae. In this review, we discuss the role of proinflammatory molecules such as cytokines, chemokines, and oxygen reactive species in modulating DA homeostasis. Moreover, we review the existing literature on the possible mechanistic interplay between SARS-CoV-2-mediated neuroinflammation and nigrostriatal DAergic impairment, and the cross-talk with aberrant α-syn metabolism.

How viral infections cause neuronal dysfunction: a focus on the role of microglia and astrocytes

In recent decades, a number of infectious viruses have emerged from wildlife or reemerged that pose a serious threat to global health and economies worldwide. Although many of these viruses have a specific target tissue, neurotropic viruses have evolved mechanisms to exploit weaknesses in immune defenses that eventually allow them to reach and infect cells of the central nervous system (CNS). Once in the CNS, these viruses can cause severe neuronal damage, sometimes with long-lasting, life-threatening consequences. Remarkably, the ability to enter the CNS and cause neuronal infection does not appear to determine whether a viral strain causes neurological complications. The cellular mechanisms underlying the neurological consequences of viral infection are not fully understood, but they involve neuroimmune interactions that have so far focused mainly on microglia. As the major immune cells in the brain, reactive microglia play a central role in neuroinflammation by responding directly or indirectly to viruses. Chronic reactivity of microglia leads to functions that are distinct from their beneficial roles under physiological conditions and may result in neuronal damage that contributes to the pathogenesis of various neurological diseases. However, there is increasing evidence that reactive astrocytes also play an important role in the response to viruses. In this review article, we summarize the recent contributions of microglia and astrocytes to the neurological impairments caused by viral infections. By expanding knowledge in this area, therapeutic approaches targeting immunological pathways may reduce the incidence of neurological and neurodegenerative disorders and increase the therapeutic window for neural protection.

Evolutionary Aspects of Diverse Microbial Exposures and Mental Health: Focus on "Old Friends" and Stress Resilience

The prevalence of inflammatory disease conditions, including allergies, asthma, and autoimmune disorders, increased during the latter half of the twentieth century, as societies transitioned from rural to urban lifestyles. A number of hypotheses have been put forward to explain the increasing prevalence of inflammatory disease in modern urban societies, including the hygiene hypothesis and the "Old Friends" hypothesis. In 2008, Rook and Lowry proposed, based on the evidence that increased inflammation was a risk factor for stress-related psychiatric disorders, that the hygiene hypothesis or "Old Friends" hypothesis may be relevant to psychiatric disorders. Since then, it has become more clear that chronic low-grade inflammation is a risk factor for stress-related psychiatric disorders, including anxiety disorders, mood disorders, and trauma- and stressor-related disorders, such as posttraumatic stress disorder (PTSD). Evidence now indicates that persons raised in modern urban environments without daily contact with pets, relative to persons raised in rural environments in proximity to farm animals, respond with greater systemic inflammation to psychosocial stress. Here we consider the possibility that increased inflammation in persons living in modern urban environments is due to a failure of immunoregulation, i.e., a balanced expression of regulatory and effector T cells, which is known to be dependent on microbial signals. We highlight evidence that microbial signals that can drive immunoregulation arise from phylogenetically diverse taxa but are strain specific. Finally, we highlight Mycobacterium vaccae NCTC 11659, a soil-derived bacterium with anti-inflammatory and immunoregulatory properties, as a case study of how single strains of bacteria might be used in a psychoneuroimmunologic approach for prevention and treatment of stress-related psychiatric disorders.

Assessment of Immune Status Using Inexpensive Cytokines: A Literature Review and Learning Approaches

The emergence of point-of-care (POC) testing has lately been promoted to deliver rapid, reliable medical tests in critical life-threatening situations, especially in resource-limited settings. Recently, POC tests have witnessed further advances due to the technological revolution in smartphones. Smartphones are integrated as reliable readers to the POC results to improve their quantitative detection. This has enabled the use of more complex medical tests by the patient him/herself at home without the need for professional staff and sophisticated equipment. Cytokines, the important immune system biomarkers, are still measured today using the time-consuming Enzyme-Linked Immunosorbent Assay (ELISA), which can only be performed in specially equipped laboratories. Therefore, in this study, we investigate the current development of POC technologies suitable for the home testing of cytokines by conducting a PRISMA literature review. Then, we classify the collected technologies as inexpensive and expensive depending on whether the cytokines can be measured easily at home or not. Additionally, we propose a machine learning-based solution to even increase the efficiency of the cytokine measurement by leveraging the cytokines that can be inexpensively measured to predict the values of the expensive ones. In total, we identify 12 POCs for cytokine quantification. We find that Interleukin 1β (IL-1β), Interleukin 3 (IL-3), Interleukin 6 (IL-6), Interleukin 8 (IL-8) and Tumor necrosis factor (TNF) can be measured with inexpensive POC technology, namely at home. We build machine-learning models to predict the values of other expensive cytokines such as Interferon-gamma (IFN-γ), IL-10, IL-2, IL-17A, IL-17F, IL-4 and IL-5 by relying on the identified inexpensive ones in addition to the age of the individual. We evaluate to what extent the built machine learning models can use the inexpensive cytokines to predict the expensive ones on 351 healthy subjects from the public dataset 10k Immunomes. The models for IFN-γ show high results for the coefficient of determination: R2 = 0.743. The results for IL-5 and IL-4 are also promising, whereas the predictive model of IL-10 achieves only R2 = 0.126. Lastly, the results demonstrate the vital role of TNF and IL-6 in the immune system due to its high importance in the predictions of all the other expensive cytokines.

CY-09 Alleviates the Depression-like Behaviors via Inhibiting NLRP3 Inflammasome-Mediated Neuroinflammation in Lipopolysaccharide-Induced Mice

Depression is a serious mental illness, mainly characterized as large mood swings and sleep, diet, and cognitive function disorders. NLPR3, one of the inflammasomes that can be activated by a variety of stimuli to promote the maturation and secretion of pro-inflammatory cytokines, has been considered to be involved in the pathophysiology of depression. In this study, the putative role of CY-09, a selective and direct inhibitor of NLRP3, was evaluated in the lipopolysaccharide (LPS)-induced mice. The results of the study indicated that CY-09 significantly decreased the levels of NLRP3 in the hippocampus of LPS-induced mice. In addition, CY-09 increased the sucrose preference and shortened the immobility time in LPS-induced mice, suggesting the antidepressant-like effects of inhibiting NLRP3 inflammasome. Biochemical analysis showed that LPS significantly activated the NLRP3/ASC/cytokine signaling pathway and caused microglial activation, while CY-09 prevented the changes. Moreover, CY-09 increased the brain-derived neurotrophic factor (BDNF) only in microglia but not in the whole hippocampus. Meanwhile, CY-09 did not promote neurogenesis in the hippocampus of LPS mice. In conclusion, the results of the study showed that the antidepressant-like effects of NLRP3 inhibitor CY-09 were mediated by alleviating neuroinflammation in microglia and independent of the neurotrophic function in the hippocampus.

Neutrophil-to-Lymphocyte Ratio, Platelet-to-Lymphocyte Ratio, and Monocyte-to-Lymphocyte Ratio in Depression: An Updated Systematic Review and Meta-Analysis

BACKGROUND

Research on neutrophil-to-lymphocyte ratio (NLR), platelet-to-lymphocyte ratio (PLR), and monocyte-to-lymphocyte ratio (MLR) in depression is still emerging and has increased 3-fold since the first meta-analysis. An updated meta-analysis with sufficient studies can provide more evidence for a potential relationship between NLR, PLR, MLR, and depression.

METHODS

We identified 18 studies from the PubMed, EMBASE, Cochrane library, and Web of Science databases. Meta-analyses were performed to generate pooled standardized mean differences (SMDs) and 95% confidence intervals (CIs) between patients with depression and controls. Sensitivity analysis, subgroup analysis, meta-regression, and publication bias were conducted.

RESULTS

A total of 18 studies including 2,264 depressed patients and 2,415 controls were included. Depressed patients had significantly higher NLR and PLR compared with controls (SMD = 0.33, 95% CI: 0.15-0.52, p < 0.001 and SMD = 0.24, 95% CI: 0.02-0.46, p < 0.05, respectively). MLR was slightly higher in depressed individuals compared to controls (SMD = 0.15, 95% CI: -0.26 to 0.55, p > 0.05), despite the absence of significance. Sensitivity analysis removing one study responsible for heterogeneity showed a higher and significant effect (SMD = 0.32, 95% CI: 0.20-0.44) of MLR. Three subgroup analyses of NLR, PLR, MLR, and depression revealed obvious differences in the inflammatory ratios between depressed patients and controls in China and the matched age and gender subgroup. Individuals with post-stroke depression (PSD) had higher NLR and MLR values as compared to non-PSD patients (SMD = 0.51, 95% CI: 0.36-0.67, p < 0.001 and SMD = 0.46, 95% CI: 0.12-0.79, p < 0.01, respectively). Meta-regression analyses showed that male proportion in the case group influenced the heterogeneity among studies that measured NLR values (p < 0.05).

CONCLUSIONS

Higher inflammatory ratios, especially NLR, were significantly associated with an increased risk of depression. In the subgroup of China and matched age and gender, NLR, PLR, and MLR were all elevated in depressed patients vs. controls. Individuals with PSD had higher NLR and MLR values as compared to non-PSD patients. Gender differences may have an effect on NLR values in patients with depression.

Alpha2-antiplasmin deficiency affects depression and anxiety-like behavior and apoptosis induced by stress in mice

OBJECTIVES

Depression is a psychiatric disorder that affects about 10% of the world's population and is accompanied by anxiety. Depression and anxiety are often caused by various stresses. However, the etiology of depression and anxiety remains unknown. It has been reported that alpha2-antiplasmin (α2AP) not only inhibits plasmin but also has various functions such as cytokine production and cell growth. This study aimed to determine the roles of α2AP on the stress-induced depression and anxiety.

METHODS

We investigated the mild repeated restraint stress-induced depressive and anxiety-like behavior in the α2AP^+/+ and α2AP^-/- mice using the social interaction test (SIT), sucrose preference test (SPT), and elevated plus maze (EPM).

RESULTS

The stresses such as the mild repeated restraint stress suppressed α2AP expression in the hippocampus of mice, and the treatment of fluoxetine (selective serotonin reuptake inhibitor [SSRI]) recovered the stress-caused α2AP suppression. We also showed that α2AP deficiency promoted the mild restraint stress-stimulated depression-like behavior such as social withdrawal and apathy and apoptosis in mice. In contrast, α2AP deficiency attenuated the mild restraint stress induced the anxiety-like behavior in mice.

CONCLUSIONS

α2AP affects the pathogenesis of depression and anxiety induced by stress.

Depression-like behavior associated with E/I imbalance of mPFC and amygdala without TRPC channels in mice of knockout IL-10 from microglia

Depression has a growing impact on public health. Accumulating evidence supports an association between depression and increased immune system activity. IL-10 is a key cytokine that inhibits excessive inflammatory responses and is related to the anti-inflammatory and protective functions of the central nervous system (CNS). Cx3cr1^CreERIL-10^-/- mice were used in our study. We aimed to identify the role of IL-10 in microglia in depression and anxiety-like behavior. We performed a series of behavioral tests on the mice; the Cx3cr1^CreERIL-10^-/- male mice showed depression- and anxiety-like behavior compared with the littermates. The expression of transient receptor potential canonical 5 (TRPC5) decreased in both the medial prefrontal cortex (mPFC) and amygdala regions. The cytokines IL-1β and IL-6 increased, and IL-10 was decreased by western blotting. The knockout mice showed different trends in the effects of synaptic proteins. In the mPFC, IL-10 knockout induced a decrease in NR2B and synaptophysin; in the amygdala region, there was a significant increase in NR2B and PSD95. IL-10 knockout from microglia induced a decrease in GAD67 and parvalbumin (Pv) in the mPFC, but not in the amygdala. Our results showed enhanced depression and anxiety-like behavior in the Cx3cr1^CreER IL-10^-/- mice, which could be related to an imbalance in local excitatory and inhibitory transmission, as well as neuroinflammation in the mPFC and amygdala. This imbalance was associated with increased local inflammation. Although many studies have demonstrated the role of TRPC channels in emotional responses, our study showed that TRPC was not involved in this process in Cx3cr1^CreERIL-10^-/- mice.

Effects of Antidepressant Treatment on Neurotrophic Factors (BDNF and IGF-1) in Patients with Major Depressive Disorder (MDD)

Major depressive disorder (MDD) remains the subject of ongoing research as a multifactorial disease and a serious public health problem. There is a growing body of literature focusing on the role of neurotrophic factors in pathophysiology of MDD. A neurotrophic hypothesis of depression proposes that abnormalities of neurotrophins serum levels lead to neuronal atrophy and decreased neurogenesis, resulting in mood disorders. Consequently, in accordance with recent findings, antidepressant treatment modifies the serum levels of neurotrophins and thus leads to a clinical improvement of MDD. The purpose of this review is to summarize the available data on the effects of various antidepressants on serum levels of neurotrophins such as brain-derived neurotrophic factor (BDNF) and insulin-like growth factor (IGF-1). In addition, the authors discuss their role as prognostic factors for treatment response in MDD. A literature search was performed using the PubMed database. Following the inclusion and exclusion criteria, nine original articles and three meta-analyses were selected. The vast majority of studies have confirmed the effect of antidepressants on BDNF levels. Research on IGF-1 is limited and insufficient to describe the correlation between different antidepressant drugs and factor serum levels; however, four studies indicated a decrease in IGF-1 after treatment. Preliminary data suggest BDNF as a promising predictor of treatment response in MDD patients. The role of IGF-1 needs further investigation.

Integrating the monoamine and cytokine hypotheses of depression: Is histamine the missing link?

Psychiatric diseases, like depression, largely affect the central nervous system (CNS). While the underlying neuropathology of depressive illness remains to be elucidated, several hypotheses have been proposed as molecular underpinnings for major depressive disorder, including the monoamine hypothesis and the cytokine hypothesis. The monoamine hypothesis has been largely supported by the pharmaceuticals that target monoamine neurotransmitters as a treatment for depression. However, these antidepressants have come under scrutiny due to their limited clinical efficacy, side effects, and delayed onset of action. The more recent, cytokine hypothesis of depression is supported by the ability of immune-active agents to induce "sickness behaviour" akin to that seen with depression. However, treatments that more selectively target inflammation have yielded inconsistent antidepressive results. As such, neither of these hypotheses can fully explain depressive illness pathology, implying that the underlying neuropathological mechanisms may encompass aspects of both theories. The goal of the current review is to integrate these two well-studied hypotheses and to propose a role for histamine as a potential unifying factor that links monoamines to cytokines. Additionally, we will focus on stress-induced depression, to provide an updated perspective of depressive illness research and thereby identify new potential targets for the treatment of major depressive disorder.

Comparative Analysis of Pathobiochemical Changes in Major Depression and Post-Traumatic Stress Disorder

Comparative analysis of available literature data on the pathogenetic neuroendocrine mechanisms of depression and post-traumatic stress disorder (PTSD) is provided in this review to identify their common features and differences. We discuss the multidirectional modifications of the activity of cortical and subcortical structures of the brain, levels of neurotransmitters and their receptors, and functions of the hypothalamic-pituitary-adrenocortical axis in depression and PTSD. The analysis shows that these disorders are examples of opposite failures in the system of adaptive stress response of the body to stressful psychotraumatic events. On this basis, it is concluded that the currently widespread use of similar approaches to treat these disorders is not justified, despite the significant similarity of their anxiety-depressive symptoms; development of differential therapeutic strategies is required.

Psychobiological mechanisms underlying the mood benefits of meditation: A narrative review

Psychological stressors can lead to distress and result in autonomic arousal and activation of a stress response. Ongoing or persistent stress can disrupt the stress response feedback mechanisms and result in elevated cortisol and pro-inflammatory cytokines which can cause damage to brain regions involved in the regulation of mood and emotion. We propose that the magnitude of the stress response experienced in response to psychological stressors depends on a number of modifiable psychological processes including an individual’s level of self-compassion, dispositional mindfulness, tendency to ruminate and attentional bias. We further propose that the stress response elected by psychological stressors can be meditated by influencing these modifiable psychological processes, and that meditation practices can decrease stress and improve mood by decreasing stress reactivity on a psychological, physiological and neurobiological level. We explore this in a narrative review.

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Meditation decreases blood pressure, heart rate, cortisol and cytokine levels.

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Meditation increases self-compassion, dispositional mindfulness and meta-cognition.

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Meditation improves attention and memory.

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Meditation results in brain changes in regions related to emotion regulation.

Effects of Antidepressant Treatment on Peripheral Biomarkers in Patients with Major Depressive Disorder (MDD)

Major depressive disorder (MDD) is one of the most prevalent mental illness and a leading cause of disability worldwide. Despite a range of effective treatments, more than 30% of patients do not achieve remission as a result of conventional therapy. In these circumstances the identification of novel drug targets and pathogenic factors becomes essential for selecting more efficacious and personalized treatment. Increasing evidence has implicated the role of inflammation in the pathophysiology of depression, revealing potential new pathways and treatment options. Moreover, convergent evidence indicates that MDD is related to disturbed neurogenesis and suggests a possible role of neurotrophic factors in recovery of function in patients. Although the influence of antidepressants on inflammatory cytokines balance was widely reported in various studies, the exact correlation between drugs used and specific cytokines and neurotrophins serum levels often remains inconsistent. Available data suggest anti-inflammatory properties of selective serotonin reuptake inhibitors (SSRIs), selective serotonin and noradrenaline inhibitors (SNRIs), and tricyclic antidepressants (TCAs) as a possible additional mechanism of reduction of depressive symptoms. In this review, we outline emerging data regarding the influence of different antidepressant drugs on a wide array of peripheral biomarkers such as interleukin (IL)-1ß, IL-2, IL-5, IL-6, IL-8, IL-10, C-reactive protein (CRP), or interferon (IFN)-γ. Presented results indicate anti-inflammatory effect for selected drugs or lack of such effect. Research in this field is insufficient to define the role of inflammatory markers as a predictor of treatment response in MDD.

Fish Hydrolysate Supplementation Containing n-3 Long Chain Polyunsaturated Fatty Acids and Peptides Prevents LPS-Induced Neuroinflammation

Neuroinflammation constitutes a normal part of the brain immune response orchestrated by microglial cells. However, a sustained and uncontrolled production of proinflammatory factors together with microglial activation contribute to the onset of a chronic low-grade inflammation, leading to neuronal damage and cognitive as well as behavioral impairments. Hence, limiting brain inflammatory response and improving the resolution of inflammation could be particularly of interest to prevent these alterations. Dietary n-3 long chain polyunsaturated fatty acids (LC-PUFAs) and low molecular weight peptides are good candidates because of their immunomodulatory and proresolutive properties. These compounds are present in a fish hydrolysate derived from marine-derived byproducts. In this study, we compared the effect of an 18-day supplementation with this fish hydrolysate to a supplementation with docosahexaenoic acid (DHA) on lipopolysaccharide (LPS)-induced inflammation in mice. In response to peripherally injected LPS, the fish hydrolysate supplementation decreased the hippocampal mRNA expression of the proinflammatory cytokines IL-6 (p < 0.001), IL-1β (p = 0.0008) and TNF-α (p < 0.0001), whereas the DHA supplementation reduced only the expression of IL-6 (p = 0.004). This decline in proinflammatory cytokine expressions was associated with an increase in the protein expression of IκB (p = 0.014 and p = 0.0054 as compared to the DHA supplementation and control groups, respectively) and to a modulation of microglial activation markers in the hippocampus. The beneficial effects of the fish hydrolysate could be due in part to the switch of the hippocampal oxylipin profile towards a more anti-inflammatory profile as compared to the DHA supplementation. Thus, the valorization of fish byproducts seems very attractive to prevent and counteract neuroinflammation.

Kynurenine and Tetrahydrobiopterin Pathways Crosstalk in Pain Hypersensitivity

Despite the identification of molecular mechanisms associated with pain persistence, no significant therapeutic improvements have been made. Advances in the understanding of the molecular mechanisms that induce pain hypersensitivity will allow the development of novel, effective, and safe therapies for chronic pain. Various pro-inflammatory cytokines are known to be increased during chronic pain, leading to sustained inflammation in the peripheral and central nervous systems. The pro-inflammatory environment activates additional metabolic routes, including the kynurenine (KYN) and tetrahydrobiopterin (BH4) pathways, which generate bioactive soluble metabolites with the potential to modulate neuropathic and inflammatory pain sensitivity. Inflammation-induced upregulation of indoleamine 2,3-dioxygenase 1 (IDO1) and guanosine triphosphate cyclohydrolase I (GTPCH), both rate-limiting enzymes of KYN and BH4 biosynthesis, respectively, have been identified in experimental chronic pain models as well in biological samples from patients affected by chronic pain. Inflammatory inducible KYN and BH4 pathways upregulation is characterized by increase in pronociceptive compounds, such as quinolinic acid (QUIN) and BH4, in addition to inflammatory mediators such as interferon gamma (IFN-γ) and tumor necrosis factor alpha (TNF-α). As expected, the pharmacologic and genetic experimental manipulation of both pathways confers analgesia. Many metabolic intermediates of these two pathways such as BH4, are known to sustain pain, while others, like xanthurenic acid (XA; a KYN pathway metabolite) have been recently shown to be an inhibitor of BH4 synthesis, opening a new avenue to treat chronic pain. This review will focus on the KYN/BH4 crosstalk in chronic pain and the potential modulation of these metabolic pathways that could induce analgesia without dependence or abuse liability.

Complement component 3 levels in the cerebrospinal fluid of cognitively intact elderly individuals with major depressive disorder

Late-life major depression (LLMD) is a risk factor for the development of mild cognitive impairment and dementia, including Alzheimer's disease (AD) and vascular dementia. Immune dysregulation and changes in innate immune responses in particular, have been implicated in the pathophysiology of both LLMD and AD. Complement system, a key component of the innate immune mechanism, is known to play an important role in synaptic plasticity and cognitive functions. However, its role in LLMD remains unknown. In the present study, we examined the levels of complement component 3 (C3, the convergence point of all complement activation pathways) in the cerebrospinal fluid (CSF) of elderly depressed subjects compared to healthy controls; as well as the relationship of CSF C3 levels with amyloid-beta (Aβ42 and Aβ40), total tau (T-tau) and phosphorylated tau (P-tau) proteins and cognition scores. CSF was obtained from 50 cognitively intact volunteers (major depression group, N = 30; comparison group, N = 20) and analyzed for levels of C3 by ELISA. C3 levels were marginally lower in the major depression group relative to the comparison group. We did not find any significant association of C3 with the AD biomarkers Aβ42 reflecting plaque pathology, P-tau related to tau pathology or the neurodegeneration biomarker T-tau. In contrast, C3 was positively correlated with CSF Aβ40, which may reflect Aβ deposition in cerebral vessel walls. We observed a negative correlation between C3 levels and Total Recall on the Buschke Selective Reminding Test (BSRT) for memory performance in the depressed subjects when controlling for education. This initial evidence on C3 status in LLMD subjects may have implications for our understanding of the pathophysiology of major depression especially in late life.

Is pain part of a systemic syndrome in head and neck cancer?

Head and neck cancers (HNC) represent 5% of all malignancies worldwide with about 180,000 cancer deaths per year. Patients with HNC are characterized by a systemic inflammatory state, generally associated with worse outcomes. Treatment-related toxicity is common among HNC patients and causes systemic consequences such as fatigue or cognitive dysfunction. The therapeutic treatments of HNC involve the release in circulation of inflammatory systemic mediators, whose effects trigger a vicious circle that may lead to functional and behavioral alterations. The areas of the head and neck are highly sensitive to pain. Literature data confirm that in HNC patients, pain is one of the most distressing symptoms across all the phases of treatment. Pain is associated with worse general conditions, depression, fatigue, impaired cognitive functions, and lower survival rate. The treatment of advanced HNC cases is multimodal and requires a multidisciplinary psycho-socio-pharmacological approach mediated by a team of experts. The pharmacological approach in management of HNC patients with pain is fundamental and involves the use of opioids, NSAIDs, steroids, or other drugs. Opioids in pain management therapy in patients with HNC could allow the pain level to be adequately monitored, thus improving quality of life. The integration of opioid and non-opioid therapy as well as non-pharmacological interventions is essential for the rehabilitation of physical, social, and psychological functions and to achieve pain control in patients with HNC. Opioid treatment is the mainstay for pain control, being used both for background and breakthrough cancer pain (BTcP) episodes. Fentanyl, easily absorbed and generally well tolerated, appears to be a possible choice due to its versatility. Non-pharmacological interventions, such as tailored yoga, physical exercise, and acupuncture, may have a role in pain management in patients with HNC.

Mitochondrial transplantation attenuates lipopolysaccharide- induced depression-like behaviors

The dysfunction of mitochondria plays important roles in the development of depression. Interestingly, increasing numbers of evidence show the therapeutic benefits of mitochondria transfer. Therefore, we hypothesized that injection of exogenous mitochondria would contribute to ameliorate depressive-like symptoms. In this study, the antidepressant-like effect of intravenous isolated mitochondria was evaluated on a lipopolysaccharide (LPS)- induced model of depression. The depressive-like behaviors were assessed using forced swim test (FST), tail suspension test (TST) and sucrose preference test. Besides, the neurogenesis, expression of brain-derived neurotrophic factor (BDNF), glial activation, neuroinflammation, oxidative stress and ATP production were determined in the hippocampus. The results showed that treatment of isolated mitochondria decreased the immobility time of mice in the FST and TST, and attenuated the decrease in sucrose preference test. Moreover, isolated mitochondria significantly reduced the activation of astrocyte and microglia as well as neuroinflammation (i.e. 1 L-1β, TNF-α and COX-2), increased BDNF expression and neurogenesis, restored the dysfunction of ATP production and oxidative stress in inflammation- induced depression. Taken together, the data suggested for the first time that injection of isolated mitochondria ameliorated LPS- induced depressive-like behaviors. The new discovery for the present study provides that mitochondrial transplantation might act as a new therapeutic strategy for MDD.

Immune control by amino acid catabolism during tumorigenesis and therapy

Immune checkpoints arise from physiological changes during tumorigenesis that reprogramme inflammatory, immunological and metabolic processes in malignant lesions and local lymphoid tissues, which constitute the immunological tumour microenvironment (TME). Improving clinical responses to immune checkpoint blockade will require deeper understanding of factors that impact local immune balance in the TME. Elevated catabolism of the amino acids tryptophan (Trp) and arginine (Arg) is a common TME hallmark at clinical presentation of cancer. Cells catabolizing Trp and Arg suppress effector T cells and stabilize regulatory T cells to suppress immunity in chronic inflammatory diseases of clinical importance, including cancers. Processes that induce Trp and Arg catabolism in the TME remain incompletely defined. Indoleamine 2,3 dioxygenase (IDO) and arginase 1 (ARG1), which catabolize Trp and Arg, respectively, respond to inflammatory cues including interferons and transforming growth factor-β (TGFβ) cytokines. Dying cells generate inflammatory signals including DNA, which is sensed to stimulate the production of type I interferons via the stimulator of interferon genes (STING) adaptor. Thus, dying cells help establish local conditions that suppress antitumour immunity to promote tumorigenesis. Here, we review evidence that Trp and Arg catabolism contributes to inflammatory processes that promote tumorigenesis, impede immune responses to therapy and might promote neurological comorbidities associated with cancer.

Old Friends, immunoregulation, and stress resilience

There is a considerable body of evidence indicating that chronic adverse experience, especially chronic psychosocial stress/trauma, represents a major risk factor for the development of many somatic and affective disorders, including inflammatory bowel disease (IBD) and posttraumatic stress disorder (PTSD). However, the mechanisms underlying the development of chronic stress-associated disorders are still in large part unknown, and current treatment and prevention strategies lack efficacy and reliability. A greater understanding of mechanisms involved in the development and persistence of chronic stress-induced disorders may lead to novel approaches to prevention and treatment of these disorders. In this review, we provide evidence indicating that increases in immune (re-)activity and inflammation, potentially promoted by a reduced exposure to immunoregulatory microorganisms ("Old Friends") in today's modern society, may be causal factors in mediating the vulnerability to development and persistence of stress-related pathologies. Moreover, we discuss strategies to increase immunoregulatory processes and attenuate inflammation, as for instance contact with immunoregulatory Old Friends, which appears to be a promising strategy to promote stress resilience and to prevent/treat chronic stress-related disorders.

Sex Specific Changes in Tryptophan Breakdown Over a 6 Week Treatment Period

Introduction: Despite the knowledge of sex differences concerning neurobiological parameters as well as clinical course of illness in individuals with mood disorders, the literature concerning tryptophan (Trp) breakdown, specific for women and men, is sparse to date. The current study aimed to evaluate sex differences in Trp, kynurenine (Kyn) and Kyn/Trp concentrations in general, as well as differences in changes of those concentrations over the course of a 6-week rehabilitation program in individuals with life-time unipolar affective disorder. For this purpose changes in Trp and Kyn as well as the Kyn/Trp concentrations between the time of admission (t1) and discharge (t2) were analyzed in dependence of sex. Furthermore, correlations between Trp and Kyn levels and clinical parameters were performed separately for male and female participants. Material and Methods: Results: For the current analysis 426 individuals with lifetime affective disorder completing a 6-week rehabilitation program were included. In both sexes, psychiatric symptoms decreased significantly over time. There was a significant difference between women (n = 242) and men (n = 184) regarding the changes in Trp, Kyn, and Kyn/Trp over time even if controlled for relevant covariates [multivariate: F _{(3, 380)} = 2.663, η² = 0.021, p = 0.048]. Kyn as well as Kyn/Trp concentrations increased significantly in men over time (Kyn F = 4.809, η² = 0.012, p = 0.029; Kyn/Trp F = 7.923, η² = 0.020, p = 0.005). Results remained the same when controlled for psychiatric symptoms. Discussion: The main finding of the present study is the significant difference between women and men regarding the change in Trp, Kyn, and Kyn/Trp over a 6-week psychiatric treatment period, while the depression severity scores as well as general psychiatric symptoms decreased. Sex specific changes in Trp-Kyn pathways have only been explored to a very small extent to date in the literature but are of high clinical relevance in the context of personalized medicine.

Inhibition of activated astrocyte ameliorates lipopolysaccharide- induced depressive-like behaviors

BACKGROUND

Numerous studies indicate that inflammation plays important roles in the development of depression. Astrocytes are crucial regulators of immune response in the central nervous system, and strongly activated by pro-inflammatory cytokines. We hypothesized that inhibition of activated astrocytes contributed to ameliorate depressive-like symptoms.

METHODS

This study evaluated the antidepressant-like effect of inhibition of activated astrocytes, by a well-established astrocyte inactivator fluorocitrate (FC), on a lipopolysaccharide (LPS)-induced model of depression. Forced swim test (FST), tail suspension test (TST) and sucrose preference test were used to assess depressive-like behaviors. The expression of fibrillary acidic protein (GFAP), brain-derived neurotrophic factor (BDNF) and neuroinflammation were determined in the hippocampus and cortex.

RESULTS

The results demonstrated that LPS increased immobility time in the TST and FST, reduced sucrose preference as well. LPS also enhanced the expression of IL-1β, TNF-α, iNOS and GFAP, accompanying with decreased expression of BDNF in the hippocampus and cortex. Inhibition of activated astrocytes by FC significantly prevented LPS- induced alteration in the FST, TST and sucrose preference test. Moreover, in the hippocampus and cortex, inhibition of activated astrocytes by FC significantly attenuated increases of neuroinflammation and GFAP whereas reversed decrease of BDNF in LPS- challenged depression.

CONCLUSIONS

Taken together, the results suggest that inhibition of activated astrocytes ameliorates LPS-induced depressive-like behavior, providing the first evidence that inhibition of activated astrocytes might represent a novel therapeutic target for depression.

Neuroimmune signaling in alcohol use disorder

Alcohol use disorder (AUD) is a widespread disease with limited treatment options. Targeting the neuroimmune system is a new avenue for developing or repurposing effective pharmacotherapies. Alcohol modulates innate immune signaling in different cell types in the brain by altering gene expression and the molecular pathways that regulate neuroinflammation. Chronic alcohol abuse may cause an imbalance in neuroimmune function, resulting in prolonged perturbations in brain function. Likewise, manipulating the neuroimmune system may change alcohol-related behaviors. Psychiatric disorders that are comorbid with AUD, such as post-traumatic stress disorder, major depressive disorder, and other substance use disorders, may also have underlying neuroimmune mechanisms; current evidence suggests that convergent immune pathways may be involved in AUD and in these comorbid disorders. In this review, we provide an overview of major neuroimmune cell-types and pathways involved in mediating alcohol behaviors, discuss potential mechanisms of alcohol-induced neuroimmune activation, and present recent clinical evidence for candidate immune-related drugs to treat AUD.

Antidepressant effects of direct-acting antivirals against hepatitis C virus-Results from a pilot study

BACKGROUND AND AIMS

The new direct-acting antiviral agents (DAA) have revolutionized the treatment of patients with chronic hepatitis C virus (HCV) infection. This study investigates to which extent DAA affect fatigue and mood and, if so, whether this results from changes to tryptophan (TRP) metabolism, as reflected by two critical biosynthetic pathways, serotonin (SRT) generation from TRP and TRP degradation through kynurenines (KYN) via indoleamine 2,3-dioxygenase (IDO).

METHODS

This study assessed 24 patients with chronic HCV infection, before (T1), during (T2: at 4 weeks) and 12 weeks post-treatment with DAA (T3) with respect to viral load, fatigue and depressive symptoms (BDI-II questionnaire), physical activity (actigraph) and plasma serotonin-tryptophan metabolites (LC/MS). The KYN:TRP ratio reflected IDO activity.

RESULTS

All participants achieved sustained virological response (SVR12) with DAA treatment (79% sofosbuvir-based). Fatigue (scores at T1:0.83 ± 0.70, T2:0.48 ± 0.70, T3:0.30 ± 0.50; P = 0.023) and depressive symptoms (scores at T1:9.8 ± 10.2, T2:6.0 ± 7.3, T3:5.0 ± 7.6; P = 0.005) improved significantly on therapy, whereas no changes were noted in five untreated controls. TRP plasma concentrations markedly decreased (T1:306 ± 179 mg/L, T2:283 ± 84 mg/L), whereas 5-HTP levels increased (T1:0.08 ± 0.01 mg/L, T2:0.10 ± 0.06 mg/L). KYN concentrations (T1:2.4 ± 2.0 mg/L, T2:3.7 ± 1.4 mg/L, P = 0.003) increased significantly during treatment, as did IDO activity (T1:0.008 ± 0.006 mg/L, T2:0.014 ± 0.004 mg/L; P < 0.001).

CONCLUSIONS

In this study, DAA exert positive and persistent effects on both fatigue and mood in patients with chronic HCV infection. These extrahepatic benefits are, at least in part, related to the modulation of TRP metabolism. The robust elevation of KYN concentrations challenges the current paradigm of low KYN levels as prerequisite for mental health.

Principles of inflammasome priming and inhibition: Implications for psychiatric disorders

The production of inflammatory proteins by the innate immune system is a tightly orchestrated procedure that allows the body to efficiently respond to exogenous and endogenous threats. Recently, accumulating evidence has indicated that disturbances in the inflammatory response system not only provoke autoimmune disorders, but also can have deleterious effects on neuronal function and mental health. As inflammation in the brain is primarily mediated by microglia, there has been an expanding focus on the mechanisms through which these cells initiate and propagate neuroinflammation. Microglia can enter persistently active states upon their initial recognition of an environmental stressor and are thereafter prone to elicit amplified and persistent inflammatory responses following subsequent exposures to stressors. A recent focus on why primed microglia cells are susceptible to environmental insults has been the NLRP3 inflammasome. Its function within the innate immune system is regulated in such a manner that supports a role for the complex in gating neuroinflammatory responses. The activation of NLRP3 inflammasome in microglia results in the cleavage of zymogen inflammatory interleukins into functional forms that elicit a number of consequential effects in the local neuronal environment. There is evidence to support the principle that within primed neuroimmune systems a lowered threshold for NLRP3 activation can cause persistent neuroinflammation or the amplified production of inflammatory cytokines, such as IL-1β and IL-18. Over the course of an individual's lifetime, persistent neuroinflammation can subsequently lead to the pathophysiological signatures that define psychological disorders. Therefore, targeting the NLRP3 inflammasome complex may represent an innovative and consequential approach to limit neuroinflammatory states in psychiatric disorders, such as major depressive disorder.

Changes in the tryptophan-kynurenine axis in association to therapeutic response in clinically depressed patients undergoing psychiatric rehabilitation

INTRODUCTION

In recent decades a number of studies have shown an association between the Tryptophan (Trp)-Kynurenine (Kyn) axis and neuropsychiatric disorders. However, the role of the Trp-Kyn pathway on the affective status in a general psychiatric cohort requires clarification. This study aimed to measure peripheral changes in Trp, Kyn and the Kyn/Trp-ratio as well as in the inflammatory markers high sensitive C-reactive protein (hsCRP) and interleukine-6 (IL-6) in individuals undergoing a six-week course of intensive treatment program comparing subgroups of treatment responders and non-responders.

METHODS

In this investigation 87 currently depressed individuals with a life-time history of depressive disorders were divided into treatment responders (n = 48) and non-responders (n = 39). The individuals were selected for an extreme group comparison out of 598 patients undergoing a 6-week psychiatric rehabilitation program in Austria. Responders were defined according to great changes in Becks Depression Inventory (BDI-II) between time of admission and discharge (BDI-II > 29 to BDI-II <14), while non-responders had no or minimal changes (BDI >20, max. 4 points change over time). Differences in the levels of Trp, Kyn, and the Kyn/Trp ratio as well as levels of hsCRP and IL-6, were compared between groups. Differences were analyzed at the time of admission as well as at discharge.

RESULTS

A significant group x time interaction was found for Kyn [F(1.82) = 5.79; p = 0.018] and the Kyn/Trp ratio [F(1.85) = 4.01, p = 0.048]. Importantly, Kyn increased significantly in the non-responder group, while the Kyn/Trp ratio decreased significantly in the responder group over time. Furthermore, changes in Kyn as well as hsCRP levels correlated significantly with changes in the body mass index over time (Kyn: r=0.24, p = 0.030; hsCRP: r=0.25, p = 0.021). No significant interactions were found for Trp and hsCRP, although they increased significantly over time.

DISCUSSION

Given the limitations of the study, we could show that the therapeutic response to a multimodal treatment in clinically depressed patients not receiving cytokine treatment is associated with changes in Kyn levels and the Kyn/Trp ratio as well as with hsCRP. However, it is too early to draw any causal conclusion. Future research should clarify relevant clinical and neurobiological parameters associated with changes in Kyn levels and Kyn/Trp ratio, especially in regard to clinical response.

Naringenin attenuates behavioral derangements induced by social defeat stress in mice via inhibition of acetylcholinesterase activity, oxidative stress and release of pro-inflammatory cytokines

The effects of naringenin; a dietary flavonoid, with potent anti-oxidant and anti-inflammatory activities on social defeat stress (SDS)-induced neurobehavioral and biochemical changes were evaluated in mice using resident-intruder paradigm. The intruder male mice were distributed into 6 groups (n = 6). Mice in group 1 (control) received vehicle (3% DMSO, i.p), group 2 (SDS-control) were also given vehicle, groups 3-5 received naringenin (10, 25 and 50 mg/kg, i.p.) while group 6 had ginseng (50 mg/kg, i.p) daily for 14 days. However, 30 min after treatment on day 7, mice in groups 2-6 were exposed to SDS for a period of 10 min confrontation with aggressive counterparts for 7 consecutive days. Neurobehavioral phenotypes: spontaneous motor activity (SMA), memory, anxiety and depression were then evaluated on day 14. Malondialdehyde (MDA), glutathione (GSH), catalase and superoxide dismutase (SOD) were then estimated in the brain tissues. Acetylcholinesterase (AChE) activity and the concentrations of tumor necrosis factor-alpha (TNF-α) and interleukin-1beta (IL-1β) were also determined. SDS-induced neurobehavioral deficits were significantly (p < 0.05) attenuated by naringenin. The increased brain level of MDA (13.00 ± 0.63 μmol/g tissue) relative to vehicle-control (6.50 ± 0.43 μmol/g tissue) was significantly (p < 0.05) reduced to 5.50 ± 0.22 μmol/g tissue by naringenin (50 mg/kg). Mice exposed to SDS had decreased brain GSH level (5.17 ± 0.40 μmol/g tissue) relative to control (11.67 ± 0.84 μmol/g tissue). However, naringenin (50 mg/kg) significantly (p < 0.05) elevated GSH content (13.33 ± 0.88 μmol/g tissue) in the brains of SDS-mice. Moreover, 50 mg/Kg of naringenin (38.13 ± 2.38 ρg/mL) attenuated (p < 0.05) increased TNF-α level when compared with SDS (49.69 ± 2.81 ρg/mL). SDS-induced increase in brain level of IL-1β (236.5 ± 6.92 ρg/mL) was significantly (p < 0.05) reduced by naringenin (219.90 ± 15.25 ρg/mL). Naringenin also elevated antioxidant enzymes and decreased AChE activity in the brains of mice exposed to SDS (p < 0.05). These findings suggest that naringenin attenuates SDS-induced neurobehavioral deficits through inhibition of acetylcholinesterase activity, oxidative stress and release of pro-inflammatory cytokines.

A review of brain insulin signaling in mood disorders: From biomarker to clinical target

Patients with mood disorders are at increased risk for metabolic dysfunction. Co-occurrence of the two conditions is typically associated with a more severe disease course and poorer treatment outcomes. The specific pathophysiological mechanisms underlying this bidirectional relationship between mood and metabolic dysfunction remains poorly understood. However, it is likely that impairment of metabolic processes within the brain play a critical role. The insulin signaling pathway mediates metabolic homeostasis and is important in the regulation of neurotrophic and synaptic plasticity processes, including those involved in neurodegenerative diseases like Alzheimer's. Thus, insulin signaling in the brain may serve to link metabolic function and mood. Central insulin signaling is mediated through locally secreted insulin and widespread insulin receptor expression. Here we review the preclinical and clinical data addressing the relationships between central insulin signaling, cellular metabolism, neurotrophic processes, and mood regulation, including key points of mechanistic overlap. These relationships have important implications for developing biomarker-based diagnostics and precision medicine approaches to treat severe mood disorders.

Complement component 3a receptor deficiency attenuates chronic stress-induced monocyte infiltration and depressive-like behavior

Major depressive disorder (MDD) is one of the most common and debilitating neuropsychiatric illnesses. Accumulating evidence suggests a potential role of the immune system in the pathophysiology of MDD. The complement system represents one of the major effector mechanisms of the innate immune system, and plays a critical role in inflammation. However, the role of complement components in MDD is not well understood. Here, we found significant increase in component 3 (C3) expression in the prefrontal cortex (PFC) of depressed suicide subjects. We tested the role of altered C3 expression in mouse model of depression and found that increased C3 expression in PFC as a result of chronic stress causes depressive-like behavior. Conversely, mice lacking C3 were resilient to stress-induced depressive-like behavior. Moreover, selective overexpression of C3 in PFC was sufficient to cause depressive-like behavior in mice. We found that C3a (activated product of C3) receptor, C3aR+ monocytes were infiltrated into PFC following chronic stress. However, C3aR knockout mice displayed significantly reduced monocyte recruitment into PFC and reduced levels of the proinflammatory cytokine IL-1β in PFC after chronic stress. In addition, C3aR knockout mice did not exhibit chronic stress-induced behavior despair. Similarly, chronic stress-induced increases in C3aR+ monocytes and IL-1β in PFC, and depressive-like behavior were attenuated by myeloid cell depletion. These postmortem and preclinical studies identify C3aR signaling as a key factor in MDD pathophysiology.

Methyl jasmonate attenuated lipopolysaccharide-induced depressive-like behaviour in mice

Depression is a recurrent neuropsychiatric disorder that affects millions of individuals worldwide and impact negatively on the patients' social functions and quality of life. Studies have shown that i.p injection of lipopolysaccharide (LPS) induces depressive-like behavior in rodents via induction of oxidative stress and neuroinflammation. Methyl jasmonate (MJ), an isolated compound from jasmine plant has gained reputation in aromatherapy for treatment of depression, nervousness and memory deficits. This study was designed to evaluate the effects of MJ on LPS-induced depressive-like behavior in mice. Mice were given MJ (5-20 mg/kg), imipramine (10 mg/kg) or vehicle (10 mL/kg) intraperitoneally for 7 consecutive days. On day 7, treatment was carried out 30 min prior to i.p injection of LPS (830 μg/kg). Twenty four hours after LPS administration, tail suspension, forced swim and sucrose preference tests were carried out. Thereafter, serum corticosterone levels were determined using ELISA. The levels of malondialdehyde (MDA), glutathione (GSH) and tumor necrosis factor-alpha (TNF-α) were determined in brain tissue homogenates. LPS significantly increased immobility time in the tail suspension and forced swim tests when compared with vehicle (p < 0.05), which indicates depressive-like syndromes. However, the increased immobility time was significantly reduced by MJ (5-20 mg/kg) when compared with LPS-treated group. LPS administration also altered the levels of MDA, GSH, corticosterone and TNF alpha in mice, which was significantly reversed by MJ. These findings suggest that attenuation of LPS-induced depressive-like behavior by MJ may be related to suppression of oxidative stress and release of TNF alpha.

Contributions of the adaptive immune system to mood regulation: Mechanisms and pathways of neuroimmune interactions

Clinical and basic studies of functional interactions between adaptive immunity, affective states, and brain function are reviewed, and the neural, humoral, and cellular routes of bidirectional communication between the brain and the adaptive immune system are evaluated. In clinical studies of depressed populations, lymphocytes-the principal cells of the adaptive immune system-exhibit altered T cell subtype ratios and CD4+ helper T cell polarization profiles. In basic studies using psychological stress to model depression, T cell profiles are altered as well, consistent with stress effects conveyed by the hypothalamic-pituitary-adrenal axis and sympathetic nervous system. Lymphocytes in turn have effects on behavior and CNS structure and function. CD4+ T cells in particular appear to modify affective behavior and rates of hippocampal dentate gyrus neurogenesis. These observations force the question of how such actions are carried out. CNS effects may occur via cellular and molecular mechanisms whereby effector memory T cells and the cytokine profiles they produce in the blood interact with the blood-brain barrier in ways that remain to be clarified. Understanding the mechanisms by which T cells polarize and interact with the brain to alter mood states is key to advances in the field, and may permit development of therapies that target cells in the periphery, thus bypassing problems associated with bioavailability of drugs within the brain.

Silybin supplementation during HCV therapy with pegylated interferon-α plus ribavirin reduces depression and anxiety and increases work ability

BACKGROUND

Hepatitis C virus infection and interferon treatment are often associated with anxiety, depressive symptoms and poor health-related quality of life. To evaluate the Silybin-vitamin E-phospholipids complex effect on work ability and whether health related factors (anxiety and depression) were associated with work ability in subjects with chronic hepatitis C treated with Pegylated-Interferon-α2b (Peg-IFN) and Ribavirin (RBV).

METHODS

Thirty-one patients (Group A) with chronic hepatitis and other 31 subjects in Group B were recruited in a randomized, prospective, placebo controlled, double blind clinical trial. Group A received 1.5 mg/kg per week of Peg-IFN plus RBV and placebo, while Group B received the same dosage of Peg-IFN plus RBV plus association of Silybin 94 mg + vitamin E 30 mg + phospholipids 194 mg in pills for 12 months. All subjects underwent to laboratory exams and questionnaires to evaluate depression (Beck Depression Inventory - BDI), anxiety (State-trait anxiety inventory - STAI) and work ability (Work ability Index - WAI).

RESULTS

The comparison between group A and group B showed significant differences after 6 months in ALT (P < 0.001), and viremia (P < 0.05), after 12 months in ALT (P < 0.001), and AST (P < 0.001), at follow up in AST (P < 0.05), and ALT (P < 0.001). Significant difference were observed after 1 month in WAI (p < 0.001) and BDI (P < 0.05), after 6 months in WAI (P < 0.05) and STAI (P < 0.05), after 12 months and at follow up in WAI, STAI and BDI (p < 0.01).

CONCLUSIONS

The supplementation with Silybin-vitamin E -phospholipids complex increased work ability and reduced depression and anxiety in patients treated with Peg-IFN and RBV.

TRIAL REGISTRATION

NCT01957319 , First received: September 25, 2013. Last updated: September 30, 2013 (retrospectively registered).

Antidepressant-like effect of pramipexole in an inflammatory model of depression

Pramipexole (PPX), a dopamine D2/3 receptor preferring agonist, is currently in use for the treatment of Parkinson's disease symptoms and restless legs syndrome. Recently, anti-inflammatory properties of PPX have been shown in an autoimmune model of multiple sclerosis, and case reports indicate PPX ameliorates depressive symptoms. Since peripheral inflammation is known to induce depression-like behavior in rodents, we assessed the potential antidepressant effect of PPX in an inflammatory model of depression induced by LPS. Repeated (daily for 7days, 1mg/kg, i.p.), but not acute (1h before LPS) treatment with PPX abolished the depression-like behavior induced by LPS (0.1mg/kg, i.p.) in the forced swim test, and the anhedonic behavior in the splash test. Interestingly, PPX per se decreased interleukin 1β levels and reversed LPS-induced increase in its content in mice hippocampus⋅ Repeated PPX treatment also prevented the increase in hippocampal levels of the 3-nitrotyrosine protein adducts induced by LPS. Haloperidol (0.2mg/kg, i.p.) and sulpiride (50mg/kg, i.p.) were unable to prevent the antidepressant-like effect of PPX in LPS-treated mice. Altogether, these results suggest that the observed antidepressant-like effect of PPX in LPS-treated mice may be dependent on its anti-inflammatory properties and may not be related to dopamine D2 receptor activation.

Integrating neuroimmune systems in the neurobiology of depression

Data from clinical and preclinical studies indicate that immune dysregulation, specifically of inflammatory processes, is associated with symptoms of major depressive disorder (MDD). In particular, increased levels of circulating pro-inflammatory cytokines and concomitant activation of brain-resident microglia can lead to depressive behavioural symptoms. Repeated exposure to psychological stress has a profound impact on peripheral immune responses and perturbs the function of brain microglia, which may contribute to neurobiological changes underlying MDD. Here, we review these findings and discuss ongoing studies examining neuroimmune mechanisms that influence neuronal activity as well as synaptic plasticity. Interventions targeting immune-related cellular and molecular pathways may benefit subsets of MDD patients with immune dysregulation.

T helper 17 cells may drive neuroprogression in major depressive disorder: Proposal of an integrative model

The exact pathophysiology of major depressive disorder (MDD) remains elusive. The monoamine theory, which hypothesizes that MDD emerges as a result of dysfunctional serotonergic, dopaminergic and noradrenergic pathways, has guided the therapy of this illness for several decades. More recently, the involvement of activated immune, oxidative and nitrosative stress pathways and of decreased levels of neurotrophic factors has provided emerging insights regarding the pathophysiology of MDD, leading to integrated theories emphasizing the complex interplay of these mechanisms that could lead to neuroprogression. In this review, we propose an integrative model suggesting that T helper 17 (Th17) cells play a pivotal role in the pathophysiology of MDD through (i) microglial activation, (ii) interactions with oxidative and nitrosative stress, (iii) increases of autoantibody production and the propensity for autoimmunity, (iv) disruption of the blood-brain barrier, and (v) dysregulation of the gut mucosa and microbiota. The clinical and research implications of this model are discussed.

Albumin and depression in elderly stroke survivors: An observational cohort study

BACKGROUND/OBJECTIVES

Post-stroke depression affects approximately one third of stroke survivors. In non-stroke affected populations, depressive symptomatology is associated with hypoalbuminemia. This is also common among stroke survivors and associated with poor outcome and increased mortality. The role of stroke-associated hypoalbuminemia in post-stroke depression is not clear. We aimed to explore the relationship between serum albumin and post-stroke depression, as measured 20 months post-stroke.

SUBJECTS/METHODS

Observational cohort study of elderly Swedish patients drawn from the 'Gothenburg 70+ Stroke Study' (n=149) and assessed at 20 months after stroke onset. Serum albumin was drawn from venous blood and analysed with gas chromatography/mass spectrometry. Depressive symptomatology was assessed using the Montgomery-Åsberg Depression Rating Scale (MADRS) and functional impairment was assessed using the Barthel Index.

RESULTS

Analysis of covariance analysis showed that serum albumin levels were associated with depressive symptoms at 20 months after stroke. Multivariate analysis of covariance showed that disability scores at 3 days were associated with depressive symptoms at 20 months after stroke and after accounting for the age covariate. Stroke survivors were not clinically deficient in serum albumin.

CONCLUSIONS

Low serum albumin appears to be associated with depressive symptoms in elderly individuals long term post-stroke.

Systemic Lupus Erythematous Presenting as Catatonia and its Response to Electroconvulie Therapy

Neuropsychiatric systemic lupus erythematous (SLE) encompasses various psychiatric and neurological manifestations that develop in SLE patients, secondary to involvement of central nervous system. Neuropsychiatric SLE, presenting as catatonia is very uncommon, and treatment of this condition is not well defined. Previously the role of benzodiazepines, immunosuppression, plasma exchange, and electroconvulsive therapy (ECT) has been described in its management. Here we describe a case of neuropsychiatric lupus presenting as catatonia that did not respond to benzodiazepines or immunosuppression. The symptoms of catatonia showed improvement with ECT. Furthermore, we have discussed the pathology of the disorder and the role of ECT in the treatment of cases of catatonia associated with SLE, who do not respond to benzodiazepines.

A systematic review of randomised control trials on the effects of yoga on stress measures and mood

Stress related disorders such as depression and anxiety are leading sources of disability worldwide, and current treatment methods such as conventional antidepressant medications are not beneficial for all individuals. There is evidence that yoga has mood-enhancing properties possibly related to its inhibitory effects on physiological stress and inflammation, which are frequently associated with affective disorders. However the biological mechanisms via which yoga exerts its therapeutic mood-modulating effects are largely unknown. This systematic review investigates the effects of yoga on sympathetic nervous system and hypothalamic pituitary adrenal axis regulation measures. It focuses on studies collecting physiological parameters such as blood pressure, heart rate, cortisol, peripheral cytokine expression and/or structural and functional brain measures in regions involved in stress and mood regulation. Overall the 25 randomised control studies discussed provide preliminary evidence to suggest that yoga practice leads to better regulation of the sympathetic nervous system and hypothalamic-pituitary-adrenal system, as well as a decrease in depressive and anxious symptoms in a range of populations. Further research is warranted to confirm these preliminary findings and facilitate implementation in clinical settings.