Inflammation Effects on Brain Glutamate in Depression: Mechanistic Considerations and Treatment Implications

The Role of Glutamate and Blood-Brain Barrier Disruption as a Mechanistic Link between Epilepsy and Depression

Epilepsy is associated with substantial neuropsychiatric impairments that persist long after the onset of the condition, significantly impacting quality of life. The goal of this review was to uncover how the pathological consequences of epilepsy, such as excessive glutamate release and a disrupted blood-brain barrier (BBB), contribute to the emergence of neuropsychiatric disorders. We hypothesize that epilepsy induces a dysfunctional BBB through hyperexcitation, which then further amplifies post-ictal glutamate levels and, thus, triggers neurodegenerative and neuropsychiatric processes. This review identifies the determinants of glutamate concentration levels in the brain and explores potential therapeutic interventions that restore BBB integrity. Our focus on therapeutic BBB restoration is guided by the premise that it may improve glutamate regulation, consequently mitigating the neurotoxicity that contributes to the onset of neuropsychiatric symptoms.

Pentoxifylline as a Novel Add-on Therapy for Major Depressive Disorder in Adult Patients: A Randomized, Double-Blind, Placebo-Controlled Trial

BACKGROUND

Evidence indicates an association between immune dysregulation and major depressive disorder (MDD). Pentoxifylline (PTX), a phosphodiesterase inhibitor, has been shown to reduce pro-inflammatory activities. The aim of this study was to evaluate changes in depressive symptoms and pro-inflammatory markers after administration of PTX as an adjunctive agent to citalopram in patients with MDD.

METHODS

One hundred patients were randomly assigned to either citalopram (20 mg/day) plus placebo (twice daily) (n=50) or citalopram (20 mg/day) plus PTX (400 mg) (twice daily) (n=50). The Hamilton Depression Rating Scale-17 (HAM-D-17) scores at baseline, weeks 2, 4, 6, 8, 10, and 12 and serum levels of interleukin1-β (IL-1-β), tumor necrosis factor-α, C-reactive protein, IL-6, serotonin, IL-10, and brain-derived neurotrophic factor (BDNF) at baseline and week 12 were evaluated.

RESULTS

HAM-D-17 score in the PTX group significantly reduced in comparison to the control group after weeks 4, 6, 8,10, and 12 ((LSMD): - 2.193, p=0.021; - 2.597, p=0.036; - 2.916, p=0.019; - 4.336, p=0.005; and - 4.087, p=0.008, respectively). Patients who received PTX had a better response (83%) and remission rate (79%) compared to the placebo group (49% and 40%, p=0.006 and p=0.01, respectively). Moreover, the reduction in serum concentrations of pro-inflammatory factors and increase in serotonin and BDNF in the PTX group was significantly greater than in the placebo group (p<0.001).

CONCLUSION

These findings support the safety and efficacy of PTX as an adjunctive antidepressant agent with anti-inflammatory effects in patients with MDD.

Comparing the effect of fluoxetine, escitalopram, and sertraline, on the level of BDNF and depression in preclinical and clinical studies: a systematic review

Brain-derived neurotrophic factor (BDNF) dysfunction is one of the most important mechanisms underlying depression. It seems that selective serotonin reuptake inhibitors (SSRIs) improve depression via affecting BDNF level. In this systematic review, for the first time, we aimed to review the effect of three SSRIs including fluoxetine, escitalopram, and sertraline, on both depression and BDNF level in preclinical and clinical studies. PubMed electronic database was searched, and 193 articles were included in this study. After reviewing all manuscripts, only one important difference was found: subjects. We found that SSRIs induce different effects in animals vs. humans. Preclinical studies showed many controversial effects, while human studies showed only two effects: improvement of depression, with or without the improvement of BDNF. However, most studies used chronic SSRIs treatment, while acute SSRIs were not effectively used and evaluated. In conclusion, it seems that SSRIs are reliable antidepressants, and the improvement effect of SSRIs on depression is not dependent to BDNF level (at least in human studies).

Anti-inflammatory Drugs in the Treatment of Depression

The last two decades have seen a flourishing of research into the immunobiology of psychiatric phenotypes, in particular major depressive disorder. Both preclinical and clinical data have highlighted pathways and possible mechanisms that might link changes in immunobiology, most especially inflammation, to clinically relevant behaviour. From a therapeutics perspective, a major impetus has been the action of Biologics, often monoclonal antibodies, that target specific cytokines acting as "molecular scalpels" helping to uncover the actions of those proteins. These interventions have been associated with improvements in mood and related symptoms. There are now enough studies and participants to permit meta-analytic analyses of the actions of these and other anti-inflammatory agents.In this chapter, the focus is on the evidence for the role of inflammation biology in depression and the meta-analytic data from trials. The putative mechanisms that might underpin the antidepressant effect of anti-inflammatory drugs are also explored. Lastly, I describe the more stubborn difficulties around heterogeneity, deep phenotyping and stratification as well as improved animal models and greater understanding of the biology that might be addressed by future studies.

Immune mechanisms of depression in rheumatoid arthritis

Depression is a common and disabling comorbidity in rheumatoid arthritis that not only decreases the likelihood of remission and treatment adherence but also increases the risk of disability and mortality in patients with rheumatoid arthritis. Compelling data that link immune mechanisms to major depressive disorder indicate possible common mechanisms that drive the pathology of the two conditions. Preclinical evidence suggests that pro-inflammatory cytokines, which are prevalent in rheumatoid arthritis, have various effects on monoaminergic neurotransmission, neurotrophic factors and measures of synaptic plasticity. Neuroimaging studies provide insight into the consequences of inflammation on the brain (for example, on neural connectivity), and clinical trial data highlight the beneficial effects of immune modulation on comorbid depression. Major depressive disorder occurs more frequently in patients with rheumatoid arthritis than in the general population, and major depressive disorder also increases the risk of a future diagnosis of rheumatoid arthritis, further highlighting the link between rheumatoid arthritis and major depressive disorder. This Review focuses on interactions between peripheral and central immunobiological mechanisms in the context of both rheumatoid arthritis and major depressive disorder. Understanding these mechanisms will provide a basis for future therapeutic development, not least in depression.

Discrimination exposure impacts unhealthy processing of food cues: crosstalk between the brain and gut

Experiences of discrimination are associated with adverse health outcomes, including obesity. However, the mechanisms by which discrimination leads to obesity remain unclear. Utilizing multi-omics analyses of neuroimaging and fecal metabolites, we investigated the impact of discrimination exposure on brain reactivity to food images and associated dysregulations in the brain-gut-microbiome system. We show that discrimination is associated with increased food-cue reactivity in frontal-striatal regions involved in reward, motivation and executive control; altered glutamate-pathway metabolites involved in oxidative stress and inflammation as well as preference for unhealthy foods. Associations between discrimination-related brain and gut signatures were skewed towards unhealthy sweet foods after adjusting for age, diet, body mass index, race and socioeconomic status. Discrimination, as a stressor, may contribute to enhanced food-cue reactivity and brain-gut-microbiome disruptions that can promote unhealthy eating behaviors, leading to increased risk for obesity. Treatments that normalize these alterations may benefit individuals who experience discrimination-related stress.

Psilocybin induces acute and persisting alterations in immune status in healthy volunteers: An experimental, placebo-controlled study

Patients characterized by stress-related disorders such as depression display elevated circulating concentrations of pro-inflammatory cytokines and a hyperactive HPA axis. Psychedelics are demonstrating promising results in treatment of such disorders, however the mechanisms of their therapeutic effects are still unknown. To date the evidence of acute and persisting effects of psychedelics on immune functioning, HPA axis activity in response to stress, and associated psychological outcomes is preliminary. To address this, we conducted a placebo-controlled, parallel group design comprising of 60 healthy participants who received either placebo (n = 30) or 0.17 mg/kg psilocybin (n = 30). Blood samples were taken to assess acute and persisting (7 day) changes in immune status. Seven days' post-administration, participants in each treatment group were further subdivided: 15 underwent a stress induction protocol, and 15 underwent a control protocol. Ultra-high field (7-Tesla) magnetic resonance spectroscopy was used to assess whether acute changes in glutamate or glial activity were associated with changes in immune functioning. Finally, questionnaires assessed persisting self-report changes in mood and social behavior. Psilocybin immediately reduced concentrations of the pro-inflammatory cytokine tumor necrosis factor-α (TNF-α), while other inflammatory markers (interleukin (IL)- 1β, IL-6, and C-reactive protein (CRP)) remained unchanged. Seven days later, TNF-α concentrations returned to baseline, while IL-6 and CRP concentrations were persistently reduced in the psilocybin group. Changes in the immune profile were related to acute neurometabolic activity as acute reductions in TNF-α were linked to lower concentrations of glutamate in the hippocampus. Additionally, the more of a reduction in IL-6 and CRP seven days after psilocybin, the more persisting positive mood and social effects participants reported. Regarding the stress response, after a psychosocial stressor, psilocybin did not significantly alter the stress response. Results are discussed in regards to the psychological and therapeutic effects of psilocybin demonstrated in ongoing patient trials.

Influence of HIV infection on cognition and overall intelligence in HIV-infected individuals: advances and perspectives

It is now well understood that HIV-positive individuals, even those under effective ART, tend to develop a spectrum of cognitive, motor, and/or mood conditions which are contemporarily referred to as HIV-associated neurocognitive disorder (HAND), and which is directly related to HIV-1 infection and HIV-1 replication in the central nervous system (CNS). As HAND is known to induce difficulties associated with attention, concentration, and memory, it is thus legitimate and pertinent to speculate upon the possibility that HIV infection may well influence human cognition and intelligence. We therefore propose herein to review the concept of intelligence, the concept of cells of intelligence, the influence of HIV on these particular cells, and the evidence pointing to differences in observed intelligence quotient (IQ) scores between HIV-positive and HIV-negative individuals. Additionally, cumulative research evidence continues to draw attention to the influence of the gut on human intelligence. Up to now, although it is known that HIV infection profoundly alters both the composition and diversity of the gut microbiota and the structural integrity of the gut, the influence of the gut on intelligence in the context of HIV infection remains poorly described. As such, we also provide herein a review of the different ways in which HIV may influence human intelligence via the gut-brain axis. Finally, we provide a discourse on perspectives related to HIV and human intelligence which may assist in generating more robust evidence with respect to this issue in future studies. Our aim is to provide insightful knowledge for the identification of novel areas of investigation, in order to reveal and explain some of the enigmas related to HIV infection.

Exploring the impact of ketogenic diet on multiple sclerosis: obesity, anxiety, depression, and the glutamate system

Background

Multiple sclerosis (MS) is a neurodegenerative disorder. Individuals with MS frequently present symptoms such as functional disability, obesity, and anxiety and depression. Axonal demyelination can be observed and implies alterations in mitochondrial activity and increased inflammation associated with disruptions in glutamate neurotransmitter activity. In this context, the ketogenic diet (KD), which promotes the production of ketone bodies in the blood [mainly β-hydroxybutyrate (βHB)], is a non-pharmacological therapeutic alternative that has shown promising results in peripheral obesity reduction and central inflammation reduction. However, the association of this type of diet with emotional symptoms through the modulation of glutamate activity in MS individuals remains unknown.

Aim

To provide an update on the topic and discuss the potential impact of KD on anxiety and depression through the modulation of glutamate activity in subjects with MS.

Discussion

The main findings suggest that the KD, as a source of ketone bodies in the blood, improves glutamate activity by reducing obesity, which is associated with insulin resistance and dyslipidemia, promoting central inflammation (particularly through an increase in interleukins IL-1β, IL-6, and IL-17). This improvement would imply a decrease in extrasynaptic glutamate activity, which has been linked to functional disability and the presence of emotional disorders such as anxiety and depression.

Combining inflammatory miRNA molecules as diagnostic biomarkers for depression: a clinical study

Background

Inflammation has been implicated in core features of depression pathophysiology and treatment resistance. Therefore, new challenges in the discovery of inflammatory mediators implicated in depression have emerged. MicroRNAs (miRNAs) have been found aberrantly expressed in several pathologies, increasing their potential as biomarkers and therapeutical targets. In this study, the aim was to assess the changes and biomarker potential of inflammation-related miRNAs in depression patients.

Methods

Depression diagnosis was performed according to the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5). 40 healthy controls and 32 depression patients were included in the study. The levels of inflammatory cytokines were measured in plasma, and expression levels of cytokines and inflammation-related miRNAs were evaluated in peripheral blood mononuclear cells (PBMCs).

Results

Depression patients were found to have a pro-inflammatory profile in plasma, with significantly higher levels of TNF-α and CCL2 compared with controls. In PBMCs of depression patients, TNF-α and IL-6 expression levels were significantly up and downregulated, respectively. Moreover, miR-342 levels were found upregulated, while miR-146a and miR-155 were significantly downregulated. miR-342 expression levels were positively correlated with TNF-α. Importantly, when analyzed as a diagnostic panel, receiver operating characteristics (ROC) analysis of miR-342, miR-146a, miR-155 in combination, showed to be highly specific and sensitive in distinguishing between depression patients and healthy controls.

Conclusion

In summary, these findings suggest that inflammation-related miRNAs are aberrantly expressed in depression patients. Moreover, we show evidences on the potential of the combination of dysregulated miRNAs as a powerful diagnostic tool for depression.

Shared biological mechanisms of depression and obesity: focus on adipokines and lipokines

Depression and obesity are both common disorders currently affecting public health, frequently occurring simultaneously within individuals, and the relationship between these disorders is bidirectional. The association between obesity and depression is highly co-morbid and tends to significantly exacerbate metabolic and related depressive symptoms. However, the neural mechanism under the mutual control of obesity and depression is largely inscrutable. This review focuses particularly on alterations in systems that may mechanistically explain the in vivo homeostatic regulation of the obesity and depression link, such as immune-inflammatory activation, gut microbiota, neuroplasticity, HPA axis dysregulation as well as neuroendocrine regulators of energy metabolism including adipocytokines and lipokines. In addition, the review summarizes potential and future treatments for obesity and depression and raises several questions that need to be answered in future research. This review will provide a comprehensive description and localization of the biological connection between obesity and depression to better understand the co-morbidity of obesity and depression.

α7 Nicotinic acetylcholine receptor: a key receptor in the cholinergic anti-inflammatory pathway exerting an antidepressant effect

Depression is a common mental illness, which is related to monoamine neurotransmitters and the dysfunction of the cholinergic, immune, glutamatergic, and neuroendocrine systems. The hypothesis of monoamine neurotransmitters is one of the commonly recognized pathogenic mechanisms of depression; however, the drugs designed based on this hypothesis have not achieved good clinical results. A recent study demonstrated that depression and inflammation were strongly correlated, and the activation of alpha7 nicotinic acetylcholine receptor (α7 nAChR)-mediated cholinergic anti-inflammatory pathway (CAP) in the cholinergic system exhibited good therapeutic effects against depression. Therefore, anti-inflammation might be a potential direction for the treatment of depression. Moreover, it is also necessary to further reveal the key role of inflammation and α7 nAChR in the pathogenesis of depression. This review focused on the correlations between inflammation and depression as well-discussed the crucial role of α7 nAChR in the CAP.

The role of early life adversity and inflammation in stress-induced change in reward and risk processes among adolescents

BACKGROUND

Early life adversity (ELA) has long been associated with increased risk for stress-related psychopathology, particularly depression. The neuroimmune network hypothesis posits that ELA increases sensitivity to psychosocial stress, moderating the association between increases in peripheral markers of inflammation and decreases in reward outcomes linked to anhedonia and risk-taking behaviors. The present study examined this hypothesis in a sample of adolescents by using acute psychosocial stress to probe the role of inflammatory signaling in behavioral measures of reward and risk processing.

METHOD

80 adolescents [13.86 years (SD = 1.54); 45 % female], oversampled for ELA, underwent the Trier Social Stress Test for Children while providing blood samples immediately before and 60-minutes after stress onset. Blood samples were assayed for plasma IL-6. One hour before stress onset, and then 60 min after, participants completed computer-administered behavioral tasks measuring reward (Pirate Task) and risk (Balloon Analog Risk Task).

RESULTS

ELA moderated the association between increases in IL-6 and decreases in risk tolerance in pursuit of rewards (p = 0.003) and reward response bias (p = 0.04). Stress-induced increases in IL-6 were associated with decreases in pumps for rewards among adolescents exposed to high, relative to little or no, ELA. Further, greater IL-6 increases were associated with increases in bias toward high relative to low value rewards among adolescents with low adversity exposure but not among those exposed to higher adversity.

CONCLUSIONS

The present study provides the first evidence in a pediatric sample that ELA may alter the role of stress-induced inflammation in reward and risk processing, and may extend our understanding of why stress leads to depression in this high-risk population.

Electroacupuncture attenuates LPS-induced depression-like behavior through kynurenine pathway

Background

A growing body of evidence suggests that inflammation and changes in glutamate neurotransmission are two pathophysiological mechanisms underlying depression. Electroacupuncture (EA) is a common therapeutic tool for the treatment of depression. However, the potential antidepressant mechanism of EA remains obscure. The change of the kynurenine pathway (KP) is the research priority of antidepressant mechanisms. This study will investigate the role of EA on lipopolysaccharide (LPS)-induced depression-like behavior and explore its possible mechanism of action.

Methods

Lipopolysaccharide was used to induce depression-like behavior, and EA was given at Hegu (L14) and Taichong (LR3) acupoints in C57BL/6J mice. Depression-like behaviors were measured by behavioral tests, including tail suspension test (TST), sucrose preference test (SPT), force swim test (FST), and open field test (OFT). The levels of inflammatory cytokines IL-1β, IL-6, and TNF-α, and KP enzyme IDO1 were measured by qPCR and enzyme-linked immunosorbent assay (ELISA), while high-performance liquid chromatography (HPLC) was performed to detect the content of prefrontal cortex and hippocampal as well as serum glutamate, tryptophan (TRP), kynurenic (KYN), and quinolinic acid (QA).

Results

The results showed that (1) as evidenced by increased spontaneous locomotor activities, decreased immobility duration, and a stronger preference for sucrose in the sucrose preference test, EA reversed LPS-challenged depressive-like behavior. (2) EA at L14 and LR3 decreased the levels of inflammatory cytokines, inhibited IDO1, and regulated KP metabolisms, as well as lowered the concentration of glutamate. (3) EA may exert anti-depression effects by acting on the kynurenine pathway.

Conclusion

This study evaluated the effects of EA on depression-like behaviors induced by lipopolysaccharide (LPS) and its regulation of inflammation and the glutamatergic system. Our results suggest that EA can ameliorate depression-like behaviors, lower the level of inflammation, and reduce the release of glutamate, possibly through the regulation of the kynurenine pathway in the brain.

Microbiota-Gut-Brain Axis in Major Depression: A New Therapeutic Approach

Major depression is impacted by the disruption of gut microbiota. Defects in gut microbiota can lead to microbiota-gut-brain axis dysfunction and increased vulnerability to major depression. While traditional chemotherapeutic approaches, such as antidepressant use, produce an overall partial therapeutic effect on depression, the gut microbiome has emerged as an effective target for better therapeutic outcomes. Recent representative studies on the microbiota hypothesis to explore the association between gut pathophysiology and major depression have indicated that restoring gut microbiota and microbiota-gut-brain axis could alleviate depression. We reviewed studies that supported the gut microbiota hypothesis to better understand the pathophysiology of depression; we also explored reports suggesting that gut microbiota restoration is an effective approach for improving depression. These findings indicate that gut microbiota and microbiota-gut-brain axis are appropriate new therapeutic targets for major depression.

How Oxidative Stress Induces Depression?

Depression increasingly affects a wide range and a large number of people worldwide, both physically and psychologically, which makes it a social problem requiring prompt attention and management. Accumulating clinical and animal studies have provided us with substantial insights of disease pathogenesis, especially central monoamine deficiency, which considerably promotes antidepressant research and clinical treatment. The first-line antidepressants mainly target the monoamine system, whose drawbacks mainly include slow action and treatment resistant. The novel antidepressant esketamine, targeting on central glutamatergic system, rapidly and robustly alleviates depression (including treatment-resistant depression), whose efficiency is shadowed by potential addictive and psychotomimetic side effects. Thus, exploring novel depression pathogenesis is necessary, for seeking more safe and effective therapeutic methods. Emerging evidence has revealed vital involvement of oxidative stress (OS) in depression, which inspires us to pursue antioxidant pathway for depression prevention and treatment. Fully uncovering the underlying mechanisms of OS-induced depression is the first step towards the avenue, thus we summarize and expound possible downstream pathways of OS, including mitochondrial impairment and related ATP deficiency, neuroinflammation, central glutamate excitotoxicity, brain-derived neurotrophic factor/tyrosine receptor kinase B dysfunction and serotonin deficiency, the microbiota-gut-brain axis disturbance and hypothalamic-pituitary-adrenocortical axis dysregulation. We also elaborate on the intricate interactions between the multiple aspects, and molecular mechanisms mediating the interplay. Through reviewing the related research progress in the field, we hope to depict an integral overview of how OS induces depression, in order to provide fresh ideas and novel targets for the final goal of efficient treatment of the disease.

Impact of polyphenols on stress and anxiety: a systematic review of molecular mechanisms and clinical evidence

Mental health is a global public concern that contributes raising disability and premature death. Anxiety undertakes around 3.6% of the global population, while psychological stress is a condition associated to anxiety with a prevalence of 36.5%. Treatment for both mental conditions consist mainly of psychological therapy and pharmacotherapy, but the long-term drugs use can trigger adverse effects. Growing evidence shows the effect of specific food compounds on stress and anxiety treatment. The aim of this systematic review is to describe the molecular mechanisms related to dietary polyphenols administration from food matrix (considering food, juices or herbal/food extracts) and their effects on stress and/or anxiety, as well as review the available clinical evidence. Search was based on PRISMA Guidelines using peer-reviewed journal articles sourced from PubMed and Web of Science. A total of 38 articles were considered as eligible. The major effects for anxiety management were: reduction of oxidative stress and inflammation; HPA axis modulation; and regulation of some serotonergic/adrenergic pathways. There is a very limited evidence to conclude about the real effect of dietary polyphenols on stress. Although pharmacological treatment for mood disorders is essential, alternative therapies are necessary using non-pharmacological compounds to improve the long-term treatment effectiveness.

Antidepressant-like activity, active components and related mechanism of Hemerocallis citrina Baroni extracts

Hemerocallis citrina Baroni [Asphodelaceae], which is traditional herbal medicine, has been widely used for treating depressive disorders in Eastern-Asia countries. However, the active compounds and corresponding mechanism of anti-depression are not yet completely clarified. In this study, the anti-depressive activities of six H. citrina extracts were primarily evaluated. The results showed that the water extract of H. citrina flowers (HCW) displays significant anti-depressive activity. A total of 32 metabolites were identified from HCW by high-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (HPLC-Q-TOF-MS) and nuclear magnetic resonance (NMR). And then, the anti-depressive activity of the high-level compound (rutin) in HCW was also estimated. The results indicated that rutin displayed significant anti-depressive activity and was one of the main active ingredients. Finally, the anti-depressive mechanisms of HCW and rutin were investigated based on the intestinal microorganisms. The results showed that HCW and rutin increase the diversity and richness of the intestinal flora and regulate the specific intestinal microorganisms such as Bacteroides and Desulfovibrio genera in depressed mice. This work marks the first comprehensive study of the active components, anti-depressive activities and corresponding mechanisms of different H. citrina extracts, which provide a potential possibility for developing new antidepressants.

Synergistic neuroprotective effect of saikosaponin A and albiflorin on corticosterone-induced apoptosis in PC12 cells via regulation of metabolic disorders and neuroinflammation

BACKGROUND

Saikosaponin A (SSA) and albiflorin (AF) are major bioactive compounds of Radix Bupleuri and Radix Paeoniae alba respectively, which possess antidepressant effects in pharmacological experiments. However, whether SSA and AF have synergistic neuroprotective effects and the synergistic mechanisms are still unknown.

METHODS AND RESULTS

The corticosterone-induced PC12 cells apoptosis model was employed to assess the neuroprotective effects of SSA and AF, and the synergistic effect was analyzed using three mathematical models. Meanwhile, cell metabolomics was used to detect the effects on metabolite regulation of SSA and AF. Furthermore, the key metabolites, metabolic enzymes, and cellular markers were verified by ELISA and Western blotting. The results showed that the combination of SSA and AF has a synergistic neuroprotective effect. Besides, the combination could regulate more metabolites than a single agent and possessed a stronger adjustment effect on metabolites. The TCA cycle was regulated by SSA and AF via improving mitochondrial function. The purine metabolism was regulated by SSA via inhibition xanthine oxidase activity and the glutamate metabolism was regulated by AF via inhibition glutaminase activity. Moreover, the oxidative stress induced by the purine metabolism was attenuated by SSA via a reduction in the ROS level. Additionally, the inflammation induced by the oxidative stress was attenuated by the SSA and AF via inhibition of the NLRP3 protein expression.

CONCLUSIONS

This study for the first time demonstrated the synergistic neuroprotective effects of SSA and AF, and the synergistic mechanisms were involved in metabolic disorders regulation and neuroinflammation inhibition.

An anti-inflammatory and low fermentable oligo, di, and monosaccharides and polyols diet improved patient reported outcomes in fibromyalgia: A randomized controlled trial

Background

Fibromyalgia (FM) has been associated with dysbiosis and low-grade inflammation. Studies have reported that diet influences clinical features in FM.

Objective

To evaluate the effect of an anti-inflammatory and low fermentable oligo, di, and monosaccharides and polyols (FODMAP) diet on clinical outcomes of patients with FM.

Methods

This two arms Randomized Controlled Trial (NCT04007705) included 46 female patients with FM. The intervention group (n = 22) adopted an anti-inflammatory diet for 3 months, excluding gluten, dairy, added sugar, and ultra-processed foods, along with a low FODMAPs diet in the first month. The control group (n = 24) followed general healthy eating recommendations. Both diets were applied by a certified dietitian. Before and after the intervention, participants were assessed regarding pain, fatigue, gastrointestinal symptoms, quality of sleep, and quality of life, through the Revised Fibromyalgia Impact Questionnaire (FIQR), Visual Analogue Pain Scale (VAS), Visual Analog Scale from gastrointestinal symptoms (VAS GI), Brief Pain Inventory (BPI), Pittsburg Sleep Quality Index (PSQI), Fatigue Severity Survey (FSS), and The Short Form Health Survey (SF-36). A blood sample was collected and high-sensitive C-Reactive Protein and Erythrocyte Sedimentation Rate were quantified. Paired Samples t-test/Wilcoxon and independent samples t-test/Mann−Whitney were used to compare variables between groups.

Results

After intervention, there was an improvement in intervention group scores of FIQR (p = 0.001), VAS (p = 0.002), BPI (p = 0.011), FSS (p = 0.042), VAS_GI (p = 0.002), PSQI (p = 0.048), and SF36 (p = 0.045) compared to control group. Inflammatory biomarkers (hs-CRP, ESR) did not change in both groups. The intervention was beneficial in the intervention group, regardless of age, disease duration, body mass index variation, and body fat change between baseline and post-intervention.

Conclusion

An anti-inflammatory and low-FODMAP diet improved clinical features in patients with FM and may be useful as a complement to pharmacological therapy.

Clinical Trial Registration

[https://clinicaltrials.gov/ct2/show/NCT04007705], identifier [NCT04007705].

Younger women are more susceptible to inflammation: A longitudinal examination of the role of aging in inflammation and depressive symptoms

BACKGROUND

The degree to which effects of inflammation on mood and behavior vary across the lifespan remains relatively unexplored despite well-established, age-related alterations in both the immune and central nervous systems. Further, the implications of this developmental process within different symptom domains warrants careful consideration.

METHODS

Women diagnosed with breast cancer (n = 188; ages 27-89) provided blood samples and reported depressive symptoms prior to adjuvant treatment, at the end of adjuvant treatment, and 6-, 12-, and 18-months after completing adjuvant treatment via the CES-D. Blood was assayed for C-reactive Protein (CRP) and interleukin (IL)-6. We used mixed linear effect models to estimate within- and between-person effects of CRP or IL-6 on 4 domains of depressive symptoms: depressed affect, low positive affect, somatic complaints, and interpersonal problems.

RESULTS

High average inflammation was associated with elevated somatic complaints (CRP p = .009, IL-6: p = .05), interpersonal problems (CRP p = .002, IL-6 p < .001), and positive affect (IL-6 p = .03), but only among the youngest women in the sample (age 50 or younger). Younger women also reported more depressed affect at assessments when inflammation was higher (CRP p = .045, IL-6 p = .09).

CONCLUSIONS

The association between inflammation and specific depressive symptoms is dynamic and varies across the lifespan, which may help clarify apparent inconsistencies in the extant literature as well as inform more precise interventions targeting this pathway.

The relationship between cannabis use and taurine: A MRS and metabolomics study

Taurine is an essential amino acid. It has been shown to be neuroprotective including protecting against the neurotoxic effects of glutamate. The goal of the current study was to examine the relationship between CB use and taurine measured in brain using magnetic resonance spectroscopy (MRS), and peripherally from a urine sample. Two experiments are presented. The first is a reanalysis of published data that examined taurine and glutamate in the dorsal anterior cingulate of a CB user group and non-user group using MRS. The second experiment, in a separate CB user group, used metabolomics analysis to measure taurine levels in urine. Because body composition has been associated with the pharmacokinetics of cannabis and taurine levels, a moderation model was examined with body composition included as the covariate. The MRS study found taurine levels were correlated with glutamate in both groups and taurine was correlated with frequency of CB use in the CB user group. The moderation model demonstrated significant effects of CB use and BMI; the interaction was marginally significant with lower BMI individuals showing a positive relationship between CB use and taurine. A similar finding was observed for the urine analysis. Both CB use and weight, as well as the interaction were significant. In this case, individuals with higher weight showed an association between CB use and taurine levels. This study shows the feasibility and potential importance of examining the relationship between taurine and CB use as it may shed light on a mechanism that underlies the neuroprotective effects of CB.

Cancer-related inflammation and depressive symptoms: Systematic review and meta-analysis

BACKGROUND

Depressive symptoms in patients with cancer are associated with poor quality of life and decreased survival. Although inflammation is reliably associated with depression in otherwise healthy individuals, the association in patients with cancer remains unclear. Given the high prevalence of cancer-related inflammation, the authors aimed to establish the relationship between inflammation and depression in cancer patients based on extant literature.

METHODS

A systematic review and meta-analysis was performed using Preferred Reporting Items for Systematic Reviews and Meta-Analyses 2020 guidelines and registered under Prospero ID CRD42021226743. Three databases were searched including PubMed, the Cochrane Library, and PsycINFO using the following criteria for inclusion: 1) measurement of a peripheral inflammatory marker, 2) use of a validated tool/scale to measure depression, and 3) a cancer diagnosis. Risk of publication bias was assessed by Funnel plot and Egger test.

RESULTS

Seventy-three studies were included in the systematic review and 54 studies (n = 5017) were included in meta-analyses. Associations with depressive symptoms were significant for peripheral blood interleukin (IL)-6 (standardized mean difference [SMD] = 0.59; 95% confidence interval [CI], 0.35-0.82), I²  = 57.9%; tumor necrosis factor (TNF) (SMD = 0.73; 95% CI, 0.35-1.11), I²  = 74.1%; and C-reactive protein (CRP) (SMD = 0.57; 95% CI, 0.27-0.87), I²  = 0%. IL-5, IL-13, albumin, and neutrophil-to-lymphocyte ratio were associated with depressive symptoms but based on fewer studies. Most cancer settings were represented; the number of studies per inflammatory marker varied from 1 to 52.

CONCLUSIONS

Although peripheral inflammatory markers were unevenly studied, the most studied markers (IL-6, TNF, and CRP) were associated with depressive symptoms in cancer patients and may be useful for management of depressive symptoms in the cancer setting.

LAY SUMMARY

Peripheral blood inflammatory markers (IL-6, TNF, and CRP) were associated with depressive symptoms in various cancer settings. Although further studies are warranted, these findings may help identify and manage depressive symptoms in patients with cancer.

Altered Metabolomics in Bipolar Depression With Gastrointestinal Symptoms

OBJECTIVE

Although gastrointestinal (GI) symptoms are very common in patients with bipolar disorder (BD), Few studies have researched the pathomechanism behind these symptoms. In the present study, we aim at elucidate the pathomechanism of GI symptoms in BD through metabolomic analysis.

METHOD

BD patients were recruited from Shanxi Bethune Hospital that divided into two groups, each group assessed with the 24-item Hamilton Depression Rating Scale (HAMD-24) according to the presence or absence of GI symptoms. Healthy controls were recruited from the medical examination center of the same hospital. Differential metabolites were identified and further analyzed using Metabo Analyst 3.0 to identify associated metabolic pathways.

RESULTS

There were significantly higher HAMD-24 scores in the GI symptoms group than that of non-GI symptoms group (p = 0.007). Based on metabolomic analysis results, we found that the common disturbances metabolic pathway of both two patients groups was ketone body metabolism, and the unique disturbances metabolic pathways of BD with GI symptoms were fatty acid biosynthesis and tyrosine metabolism, and these changes were independent of dietary habits.

CONCLUSION

BD patients with GI symptoms exhibited disturbances in fatty acid and tyrosine metabolism, perhaps suggesting that the GI symptoms in BD patients are related to disturbances of the gut microbiome. Both groups of patients jointly exhibit disturbances of ketone body metabolism, which may serve as a biomarker for the pathogenesis of BD patients.

Depression and anxiety increase the odds of developing delirium in ICU patients; a prospective observational study

BACKGROUND

Delirium is prevalent among hospitalised patients, especially in critically ill patients. Preventing delirium by recognising its modifiable risk factors could improve life quality, decrease mortality and restrain its devastating consequences.

METHOD

We investigated 50 patients who had been hospitalised in the general ICU and monitored them for developing delirium. We employed CAM and CAM-ICU Scales to assess delirium, RASS score to determine the consciousness level, HADS questionnaire for anxiety and depression, and the demographic data questionnaire.

RESULTS

We found that 20% of ICU patients developed delirium and found a meaningful correlation between the incident delirium, older ages, visual impairment, and higher anxiety and depression scores (HADS) of first and second days of hospitalisation. By utilising logistic regression, we found that older ages, visual impairment, higher anxiety and depression scores (HADS) of the first day of hospitalisation were statistically significant to predict the risk model of developing delirium.

CONCLUSION

Depressive and anxiety symptoms were associated with higher odds of transitioning to delirium; so, at the admission time, it may be useful to screen patients for the symptoms of affective disorders, particularly, who are at higher risks for developing delirium.

Immune targets for therapeutic development in depression: towards precision medicine

Over the past two decades, compelling evidence has emerged indicating that immune mechanisms can contribute to the pathogenesis of major depressive disorder (MDD) and that drugs with primary immune targets can improve depressive symptoms. Patients with MDD are heterogeneous with respect to symptoms, treatment responses and biological correlates. Defining a narrower patient group based on biology could increase the treatment response rates in certain subgroups: a major advance in clinical psychiatry. For example, patients with MDD and elevated pro-inflammatory biomarkers are less likely to respond to conventional antidepressant drugs, but novel immune-based therapeutics could potentially address their unmet clinical needs. This article outlines a framework for developing drugs targeting a novel patient subtype within MDD and reviews the current state of neuroimmune drug development for mood disorders. We discuss evidence for a causal role of immune mechanisms in the pathogenesis of depression, together with targets under investigation in randomized controlled trials, biomarker evidence elucidating the link to neural mechanisms, biological and phenotypic patient selection strategies, and the unmet clinical need among patients with MDD.

Double-blind, randomized, placebo-controlled pilot study of the phosphodiesterase-3 inhibitor cilostazol as an adjunctive to antidepressants in patients with major depressive disorder

AIMS

Cilostazol (CLS) has shown antidepressant effect in cardiovascular patients, post-stroke depression, and animal models through its neurotrophic and antiinflammatory activities. Consequently, we aimed to investigate its safety and efficacy in patients with MDD by conducting double-blind, randomized, placebo-controlled pilot study.

METHODS

80 participants with MDD (DSM-IV criteria) and Hamilton Depression Rating Scale (HDRS) score >20 were treated with CLS 50 mg or placebo twice daily plus escitalopram (ESC) 20 mg once daily for six weeks. Patients were evaluated by HDRS scores (weeks 0, 2, 4, and 6). Serum levels of CREB1, BDNF, 5-HT, TNF-α, NF- κB, and FAM19A5 were assessed pre- and post-treatment.

RESULTS

Co-administration of CLS had markedly decreased HDRS score at all-time points compared to the placebo group (p < 0.001). Early improvement, response, and remission rates after 6 weeks were significantly higher in the CLS group (90%, 90%, 80%, respectively) than in the placebo group (25%, 65%, 50% respectively) (p < 0.001). Moreover, the CLS group was superior to the placebo group in modulation of the measured neurotrophic and inflammatory biomarkers.

CONCLUSION

CLS is safe and effective short-term adjunctive therapy in patients with MDD with no other comorbid conditions. Trial registration ID:NCT04069819.

Distinct Effects of Escitalopram and Vortioxetine on Astroglial L-Glutamate Release Associated with Connexin43

It has been established that enhancement of serotonergic transmission contributes to improvement of major depression; however, several post-mortem studies and experimental depression rodent models suggest that functional abnormalities of astrocytes play important roles in the pathomechanisms/pathophysiology of mood disorders. Direct effects of serotonin (5-HT) transporter inhibiting antidepressants on astroglial transmission systems has never been assessed in this context. Therefore, to explore the effects of antidepressants on transmission associated with astrocytes, the present study determined the effects of the selective 5-HT transporter inhibitor, escitalopram, and the 5-HT partial agonist reuptake inhibitor, vortioxetine, on astroglial L-glutamate release through activated hemichannels, and the expression of connexin43 (Cx43), type 1A (5-HT1AR) and type 7 (5-HT7R) 5-HT receptor subtypes, and extracellular signal-regulated kinase (ERK) in astrocytes using primary cultured rat cortical astrocytes in a 5-HT-free environment. Both escitalopram and 5-HT1AR antagonist (WAY100635) did not affect basal astroglial L-glutamate release or L-glutamate release through activated hemichannels. Subchronic (for seven days) administrations of vortioxetine and the 5-HT7R inverse agonist (SB269970) suppressed both basal L-glutamate release and L-glutamate release through activated hemichannels, whereas 5-HT1AR agonist (BP554) inhibited L-glutamate release through activated hemichannels, but did not affect basal L-glutamate release. In particular, WAY100635 did not affect the inhibitory effects of vortioxetine on L-glutamate release. Subchronic administration of vortioxetine, BP554 and SB269970 downregulated 5-HT1AR, 5-HT7R and phosphorylated ERK in the plasma membrane fraction, but escitalopram and WAY100635 did not affect them. Subchronic administration of SB269970 decreased Cx43 expression in the plasma membrane but did not affect the cytosol; however, subchronic administration of BP554 increased Cx43 expression in the cytosol but did not affect the plasma membrane. Subchronic vortioxetine administration increased Cx43 expression in the cytosol and decreased it in the plasma membrane. WAY100635 prevented an increased Cx43 expression in the cytosol induced by vortioxetine without affecting the reduced Cx43 expression in the plasma membrane. These results suggest that 5-HT1AR downregulation probably increases Cx43 synthesis, but 5-HT7R downregulation suppresses Cx43 trafficking to the plasma membrane. These results also suggest that the subchronic administration of therapeutic-relevant concentrations of vortioxetine inhibits both astroglial L-glutamate and Cx43 expression in the plasma membrane via 5-HT7R downregulation but enhances Cx43 synthesis in the cytosol via 5-HT1AR downregulation. This combination of the downregulation of 5-HT1AR, 5-HT7R and Cx43 in the astroglial plasma membrane induced by subchronic vortioxetine administration suggest that astrocytes is possibly involved in the pathophysiology of depression.

Circulating Cytokines Predict 1H-Proton MRS Cerebral Metabolites in Healthy Older Adults

Background: Changes in both circulating cytokines and neurochemical concentrations have been observed in aging. Patterns of change across these factors are associated with age-related pathologies, including neurodegenerative disease. More evidence to define patterns of change that are characteristic of healthy aging is needed, as is an investigation into how age-related changes in blood cytokines and brain neurochemicals may relate to one another in a healthy older adult population.

Methods: Single voxel ¹H-proton magnetic resonance spectroscopy was collected in medial frontal and medial parietal regions. Phosphocholine and glycerophosphocholine (Cho), myo-inositol (MI), N-acetylaspertate and N-acetylasperglutamate (NAA), creatine and phosphocreatine (Cr), and glutamate and glutamine (Glx) were measured in a sample of 83 healthy, cognitively normal adults aged 52–89. Blood data were collected to quantify 12 cytokines: interleukins (IL-) 2, 5, 6, 7, 8, 10, 12, 13, IL-1 β, tumor necrosis factor α (TNF-α), interferon γ (IFN-γ), and IL-17 α. Correlation analyses were performed to assess age relationships between each of these factors. Backward linear regressions were performed. Cytokine data and age were used as predictors of each cerebrospinal fluid (CSF)-corrected metabolite concentration in both voxels.

Results: Associations were identified between a variety of cytokines and concentrations of frontal NAA, Cr, and Glx, and of parietal MI, Cho, NAA, and Cr. In the frontal voxel, NAA was predicted by more IL-1B and less TNF-α, Cr by less TNF-α and more IL-5, and Glx by less TNF-α. In the parietal voxel, MI was predicted by more IL-10 and IL-8 and less IL-2, Cho by more TNF-α and less IL-2, NAA by more IL-1B and TNF-α and less IL-13, IL-2, and IL-7, and Cr by more IL-10 and less IL-2.

Conclusions: Associations were identified between circulating cytokines and neurometabolite concentrations in this sample of older adults. The present results serve as the initial evidence of relationships between circulating cytokines and neurophysiology. Findings invite further investigation to understand the physiological consequences of aging, and how peripheral inflammatory markers may relate to neurochemical concentrations in healthy aging.

The efficacy of alpha-lipoic acid in improving oxidative, inflammatory, and mood status in women with episodic migraine in a randomised, double-blind, placebo-controlled clinical trial

AIM

Migraine is a common neurovascular disorder, which is associated with severe to moderate disabling headaches. Oxidative stress and inflammation might play a role in migraine pathogenesis and the mood disorders. Considering the antioxidant and anti-inflammatory properties of alpha-lipoic acid (ALA), this study was designed to investigate its effect on oxidative, inflammatory, and mood conditions in women with episodic migraine.

METHODS

In total, 92 women with episodic migraine participated in the study. The patients were randomly divided into two groups, receiving a 300-mg capsule of ALA or placebo twice daily for 3 months. To assess the oxidative and inflammatory status, the serum levels of total antioxidant capacity (TAC), total oxidant status (TOS), glutathione (GSH), malondialdehyde (MDA), oxidative stress index (OSI), and C-reactive protein (CRP) were determined at the beginning and at the end of the intervention. A depression, anxiety, stress scale (DASS-21-items) questionnaire was used to evaluate mood status.

RESULTS

Finally, 79 patients reached the final analysis stage. At the end of the intervention, a significant decrease in the serum levels of MDA (means difference [MD]: -0.83, 95% confidence intervals (CI): -1.04, -0.62 nmol/mL vs MD: -0.32, CI: -0.48, -0.15 nmol/mL; P < .001) and CRP (MD: -0.78, CI: -1.17, -0.39 mg/L vs MD: -0.63, CI: -1.80, 0.52 mg/L; P < .001) was observed in the ALA as compared with the placebo group, but changes in serum GSH (P = .086), TAC (P = .068), TOS (P = .225), and OSI (P = .404) were not statistically significant. In addition, depression, anxiety, and stress (with P < .001, in all cases) had significantly decreased in the intervention as compared with the control group.

CONCLUSION

The results of this study suggest that ALA supplementation for 3 months has beneficial effects on improving the oxidative, inflammatory, and mood conditions of patients suffering from episodic migraine.

Ketamine's effect on inflammation and kynurenine pathway in depression: A systematic review

BACKGROUND

Ketamine is a novel rapid-acting antidepressant with high efficacy in treatment-resistant patients. Its exact therapeutic mechanisms of action are unclear; however, in recent years its anti-inflammatory properties and subsequent downstream effects on tryptophan (TRP) metabolism have sparked research interest.

AIM

This systematic review examined the effect of ketamine on inflammatory markers and TRP-kynurenine (KYN) pathway metabolites in patients with unipolar and bipolar depression and in animal models of depression.

METHODS

MEDLINE, Embase, and PsycINFO databases were searched on October 2020 (1806 to 2020).

RESULTS

Out of 807 initial results, nine human studies and 22 animal studies on rodents met the inclusion criteria. Rodent studies provided strong support for ketamine-induced decreases in pro-inflammatory cytokines, namely in interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α and indicated anti-inflammatory effects on TRP metabolism, including decreases in the enzyme indoleamine 2,3-dioxygenase (IDO). Clinical evidence was less robust with high heterogeneity between sample characteristics, but most experiments demonstrated decreases in peripheral inflammation including in IL-1β, IL-6, and TNF-α. Preliminary support was also found for reduced activation of the neurotoxic arm of the KYN pathway.

CONCLUSION

Ketamine appears to induce anti-inflammatory effects in at least a proportion of depressed patients. Suggestions for future research include investigation of markers in the central nervous system and examination of clinical relevance of inflammatory changes.

Fibromyalgia and Depression in Women: An 1H-NMR Metabolomic Study

Fibromyalgia is a chronic and systemic syndrome characterized by muscle, bone, and joint pain. It is a gender-specific condition with a 9:1 incidence ratio between women and men. Fibromyalgia is frequently associated with psychic disorders affecting the cognitive and emotional spheres. In the reported work, we compared 31 female fibromyalgia patients to 31 female healthy controls. They were analyzed for biochemical clinical parameters, for autoimmune markers, and were subjected to 1H-NMR metabolomics analysis. To identify a correlation between the metabolomic profile and the psychic condition, a subset of 19 fibromyalgia patients was subjected to HAM-A and HAM-D Hamilton depression tests. Multivariate statistical analysis showed the dysmetabolism of several metabolites involved in energy balance that are associated with systemic inflammatory conditions. The severity of depression worsens dysmetabolic conditions; conversely, glycine and glutamate, known for their critical role as neuromodulators, appear to be potential biomarkers of fibromyalgia and are associated with different severity depression conditions.

Acupuncture Can Play an Antidepressant Role by Regulating the Intestinal Microbes and Neurotransmitters in a Rat Model of Depression

BACKGROUND Acupuncture, which has many good effects and few adverse effects, is widely recognized as an alternative therapy for depression in clinical practice. This study aimed to explore the mechanism of acupuncture in antidepressant treatment. MATERIAL AND METHODS In this experiment, Sprague-Dawley rats were randomly divided into 4 groups: control, chronic unpredictable mild stress (CUMS), acupuncture, and fluoxetine groups. The CUMS, acupuncture, and fluoxetine groups were orphaned and subjected to chronic unpredictable stress for 6 weeks, and the acupuncture and fluoxetine groups were treated with their respective intervention in weeks 4-6. The body weight of rats was monitored weekly. After behavioral tests were completed, serum, feces, and hippocampal tissue of rats were collected. RESULTS The results showed that the acupuncture and fluoxetine treatments could alleviate the behavioral changes caused by CUMS. The treatments increased the total distance of rat crossing in the open-field test, prolonged the activity time of the open cross maze in the open arm, and improved the rate of sucrose consumption in the sucrose preference test. In addition, both the decreased level of dopamine (DA) and 5-hydroxytryptamine (5-HT) in serum and hippocampus caused by CUMS were improved after the treatments with acupuncture and fluoxetine, and the decreased expression of brain-derived neurotrophic factor signaling and the astrocytes in the hippocampus caused by CUMS were increased after the treatments with acupuncture and fluoxetine. Acupuncture and fluoxetine also decreased the ß isoform of calmodulin-dependent protein kinase II in the hippocampus, which was increased by CUMS. Furthermore, acupuncture regulated intestinal microbial disorders caused by CUMS, which reduced the relative abundance ratio of Bacteroidetes/Firmicutes in rats. CONCLUSIONS Our experimental results indicate that acupuncture can alleviate depression-like performance in CUMS rats by regulating intestinal microbes and neurotransmitters.

A study protocol for a randomized controlled trial of an anti-inflammatory nutritional intervention in patients with fibromyalgia

Background

This study aims to analyze the effects of a potentially anti-inflammatory nutritional intervention in disease assessment parameters, inflammatory markers, and quality of life of fibromyalgia (FM) patients.

Methods

A sample of 100 female patients diagnosed with FM, followed up at Portuguese Institute of Rheumatology (IPR) in Lisbon, is being randomly allocated in two groups. Patients in the intervention group are adopting an anti-inflammatory diet, characterized by the exemption of the intake of foods containing gluten, dairy, sugar, and ultra-processed foods, during 3 months. During the first month, a low fermentable oligo-, di-, and monosaccharides and polyols (FODMAPs) diet is implemented, along with the anti-inflammatory diet, followed by the reintroduction of all fruits and vegetables over a consecutive period of 2 months. Patients in the control group are adopting a diet based on general recommendations for healthy eating. The outcomes are pain, fatigue, quality of sleep, quality of life, gastrointestinal symptoms, and inflammation. Before and after the 3 months intervention, and also 1 month after beginning the intervention, the following questionnaires are applied: Revised Fibromyalgia Impact Questionnaire, visual analog pain scale, Brief Pain Inventory,visual analog scale from a list of common gastrointestinal and extraintestinal symptoms in FM, Short Form 36, Fatigue Severity Survey, and Pittsburg Sleep Quality Index. Ultra-sensitive serum C-reactive protein, eritrocyte sedimentation rate, and interleukin-8 are determined. Age, physical activity, anthropometric parameters, and body composition are being collected. Student’s t test will assess the association between the disease evaluation parameters, the inflammatory markers, and the dietary interventions.

Discussion

The results of this study are expected to determine whether a change in patient nutrition helps to alleviate symptoms, which would optimize medical intervention.

Trial registration

www.ClinicalTrials.gov NCT04007705. Registered on July 5, 2019.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05146-3.

Effects of infliximab on brain neurochemistry of adults with bipolar depression

OBJECTIVES

To explore the relationship between inflammation and neuronal metabolism in bipolar disorder (BD) by evaluating the neurochemical effects of the tumor necrosis factor-α (TNF-α) antagonist infliximab among individuals with bipolar depression METHODS: This is a post-hoc, exploratory analysis from a 12-week, randomized, double-blind, placebo-controlled trial with infliximab for adults with bipolar depression. We assessed the effects of infliximab on concentration of metabolites in the prefrontal cortex, using proton-magnetic resonance spectroscopy (¹H-MRS), as well as its association with clinical outcomes (i.e. depressive symptom severity and cognitive function).

RESULTS

Eighteen participants in the placebo and 15 in the infliximab group were included in this analysis. In the pre-specified primary outcome, there were no significant effects of treatment on prefrontal concentrations of N-acetylaspartate (NAA; p = 0.712). In the secondary analyses, there was a significant treatment by time interaction for glutamate (Glx; p = 0.018), indicating that Glx levels decreased in infliximab-treated patients, relative to placebo. Treatment group significantly moderated the association between changes in Glx levels and changes in a neurocognitive test (i.e. Digit Symbol Substitution Test; p = 0.014), indicating that in infliximab-treated participants reductions in Glx were associated with cognitive improvement.

CONCLUSIONS

Treatment with infliximab did not affect prefrontal NAA concentration in adults with BD. Exploratory analysis suggested a potential effect of treatment on the glutamate system, a finding that should be confirmed and validated by additional studies.

Immunological Disturbances and Neuroimaging Findings in Major Depressive Disorder (MDD) and Alcohol Use Disorder (AUD) Comorbid Patients

Mood disorders and Major Depressive Disorder, in particular, appear to be some of the most common psychiatric disorders with a high rate of comorbidity most frequently of anxiety or substance abuse disorders (alcohol use disorder). In both cases - MDD and AUD, a number of immunological disturbances are observed, such as chronic mild inflammation response, increased level of cytokines, hypercortisolaemia, which lead to specific changes in brain neurotransmitter functions. Some of the contemporary brain imaging techniques are functional magnetic resonance imaging (fMRI) and magnetic spectroscopy which are most commonly used to assess the brain metabolism and functional connectivity changes such as altered responses to emotional stimuli in MDD or overactivation of ventromedial prefrontal areas during delayed and underactivation of dorsolateral prefrontal regions during impulsive reward decisions in AUD and dysfunction of gamma-aminobutyric acid (GABA) and/or glutamate neurotransmitter systems, low NAA and myo-Inositol in both MDD and AUD.

Higher Levels of Pro-inflammatory Cytokines Are Associated With Higher Levels of Glutamate in the Anterior Cingulate Cortex in Depressed Adolescents

Animal models of stress and related conditions, including depression, have shown that elevated peripheral levels of inflammatory cytokines have downstream consequences on glutamate (Glu) in the brain. Although studies in human adults with depression have reported evidence of higher inflammation but lower Glu in the anterior cingulate cortex (ACC), the extent to which peripheral inflammation contributes to glutamatergic abnormalities in adolescents with depression is not well-understood. It is also unclear whether antioxidants, such as ascorbate (Asc), may buffer against the effects of inflammation on Glu metabolism. Fifty-five depressed adolescents were recruited in the present cross-sectional study and provided blood samples, from which we assayed pro-inflammatory cytokines, and underwent a short-TE proton magnetic spectroscopy scan at 3T, from which we estimated Glu and Asc in the dorsal ACC. In the 31 adolescents with usable cytokine and Glu data, we found that IL-6 was significantly positively associated with dorsal ACC Glu (β = 0.466 ± 0.199, p = 0.029). Of the 16 participants who had usable Asc data, we found that at higher levels of dorsal ACC Asc, there was a negative association between IL-6 and Glu (interaction effect: β = -0.906 ± 0.433, p = 0.034). Importantly, these results remained significant when controlling for age, gender, percentage of gray matter in the dorsal ACC voxel, BMI, and medication (antidepressant and anti-inflammatory) usage. While preliminary, our results underscore the importance of examining both immune and neural contributors to depression and highlight the potential role of anti-inflammatory compounds in mitigating the adverse effects of inflammation (e.g., glutamatergic neuroexcitotoxicity). Future studies that experimentally manipulate levels of inflammation, and of ascorbate, and that characterize these effects on cortical glutamate concentrations and subsequent behavior in animals and in humans are needed.

The role of anthranilic acid in the increase of depressive symptoms and major depressive disorder during treatment for hepatitis C with pegylated interferon-α2a and oral ribavirin

BACKGROUND

Tryptophan metabolism via the kynurenine pathway is considered the link between the immune and endocrine systems. Dysregulation of serotonergic transmission can stem from the direct influence of interferon-α on the activity of serotonergic receptors 5-HT1A and 5-HT2A, and from its indirect effect on tryptophan metabolism. Induction of the kynurenine pathway increases the concentration of neurotoxic kynurenine metabolites, and the activity of kynurenine derivatives is linked to the onset of depression. The aim of our study was to evaluate the relationships between depressive symptoms and kynurenine, tryptophan, anthranilic acid and kynurenic acid concentrations, indolamine 2,3-dioxygenase (IDO) activity and tryptophan availability to the brain.

METHODS

The study followed a prospective longitudinal cohort design. We evaluated 101 patients with chronic hepatitis C who were treated with pegylated interferon-α2a, and 40 controls who were awaiting treatment. We evaluated the relationships between total score on the Montgomery-Åsberg Depression Rating Scale and kynurenine, tryptophan, anthranilic acid and kynurenic acid concentrations, IDO activity and tryptophan availability to the brain. A logistic regression model was adapted for the diagnosis of major depressive disorder at each time point, taking into account changes in parameters of the kynurenine pathway between a given time point and the baseline measurement.

RESULTS

Of the treated patients, 44% fulfilled the criteria for major depressive disorder at least once during the 24 weeks of treatment. Anthranilic acid concentrations were significantly increased compared to baseline for all time points except week 2. Tryptophan availability showed a significant decrease (β = -0.09, p = 0.01) only in week 12 of treatment. Over time, kynurenine, tryptophan and anthranilic acid concentrations, as well as IDO activity and tryptophan availability to the brain, were significantly associated with total score on the Montgomery-Åsberg Depression Rating Scale. A logistic regression model revealed that participants with decreased tryptophan availability to the brain at 12 weeks of treatment and participants with increased anthranilic acid concentrations at week 24 of treatment were at increased risk for diagnosis of major depressive disorder (odds ratios 2.92 and 3.59, respectively).

LIMITATIONS

This study had an open-label design in a population receiving naturalistic treatment.

CONCLUSION

The present study provides the first direct evidence of the role of anthranilic acid in the pathogenesis of inflammation-induced major depressive disorder during treatment for hepatitis C with pegylated interferon-α2a.

Sick for science: experimental endotoxemia as a translational tool to develop and test new therapies for inflammation-associated depression

Depression is one of the global leading causes of disability, but treatments remain limited and classical antidepressants were found to be ineffective in a substantial proportion of patients. Thus, novel effective therapies for the treatment of depression are urgently needed. Given the emerging role of inflammation in the etiology and pathophysiology of affective disorders, we herein illustrate how experimental endotoxemia, a translational model of systemic inflammation, could be used as a tool to develop and test new therapeutic options against depression. Our concept is based on the striking overlap of inflammatory, neural, and affective characteristics in patients with inflammation-associated depression and in endotoxin-challenged healthy subjects. Experimental administration of endotoxin in healthy volunteers is safe, well-tolerated, and without known long-term health risks. It offers a highly standardized translational approach to characterize potential targets of therapies against inflammation-associated depression, as well as to identify characteristics of patients that would benefit from these interventions, and, therefore, could contribute to improve personalization of treatment and to increase the overall rate of responders.

The intervention of unique plant polysaccharides - Dietary fiber on depression from the gut-brain axis

As an invisible organ of human body, the gut microbiota plays an important role in human life and has become a hot spot in the field of life science in recent years. Due to the increasing pressure of work and life, people are prone to depression. The in-depth mechanism studies indicated that the gut microbiota could improve the depression symptom through the gut-brain axis (GBA). As unique plant polysaccharides, dietary fiber can effectively modulate the intestinal flora disorders and its crucial role in orchestrating host-microbiota crosstalk has been confirmed. This review highlights the mechanisms that the gut microbiota affects the development of depression through GBA and focuses on dietary fiber intervention on the improvement of intestinal microbiota imbalance, which may provide new ideas for the prevention and treatment of depression.

The Possible Importance of Glutamine Supplementation to Mood and Cognition in Hypoxia from High Altitude

Hypoxia induced by low O₂ pressure is responsible for several physiological and behavioral alterations. Changes in physiological systems are frequent, including inflammation and psychobiological declines such as mood and cognition worsening, resulting in increased reaction time, difficulty solving problems, reduced memory and concentration. The paper discusses the possible relationship between glutamine supplementation and worsening cognition mediated by inflammation induced by high altitude hypoxia. The paper is a narrative literature review conducted to verify the effects of glutamine supplementation on psychobiological aspects. We searched MEDLINE/PubMed and Web of Science databases and gray literature by Google Scholar for English articles. Mechanistic pathways mediated by glutamine suggest potential positive effects of its supplementation on mood and cognition, mainly its potential effect on inflammation. However, clinical studies are scarce, making any conclusions impossible. Although glutamine plays an important role and seems to mitigate inflammation, clinical studies should test this hypothesis, which will contribute to a better mood and cognition state for several people who suffer from problems mediated by hypoxia.

Liquiritin protects PC12 cells from corticosterone-induced neurotoxicity via regulation of metabolic disorders, attenuation ERK1/2-NF-κB pathway, activation Nrf2-Keap1 pathway, and inhibition mitochondrial apoptosis pathway

Liquiritin, a flavone derived from the medicine food homology plant liquorice, possesses neuroprotective. However, the neuroprotective mechanism is not clear. In this study, metabolomics based LC-MS was performed to discover the metabolite changes in PC12 cells treated with corticosterone-induced neurotoxicity after liquiritin treatment. A total of 30 metabolites were identified as differential metabolites. Among them, 11 metabolites were regulated by liquiritin, and involved in the D-glutamine and D-glutamate metabolism, and glutathione metabolism, etc. Based on the results of metabolomics, three cell signaling pathways related to these metabolic pathways were verified. The results showed that the ERK1/2-NF-κB pathway related to the D-glutamine and D-glutamate metabolism was attenuated by liquiritin via down-regulation phospho-ERK1/2, phospho-IκBα, phospho-NF-κB protein expression levels. Furthermore, the Nrf2-Keap1 pathway related to glutathione metabolism was activated by liquiritin via up-regulation Nrf2, Keap1, HO-1, NQO1 protein expression levels, and increased SOD, CAT, GSH-PX enzyme activity, thus exerting antioxidant activity. Additionally, liquiritin inhibited the mitochondrial apoptosis by decreasing the Ca²⁺ concentration, improving MMP, up-regulating Bcl-2, and down-regulating Bax, cytochrome C, cleaved-Caspase-3 expression levels. These results suggest that the neuroprotective mechanisms of liquiritin are connected to the regulation of metabolic disorders, activation Nrf2/Keap1 pathway, attenuation ERK1/2/NF-κB pathway, and inhibition mitochondrial apoptosis pathway.

The Antidiabetic Metformin as an Adjunct to Antidepressants in Patients with Major Depressive Disorder: A Proof-of-Concept, Randomized, Double-Blind, Placebo-Controlled Trial

Metformin (MET) has been reported to have antidepressant effects in animal models and in diabetic patients with depression, owing to its anti-inflammatory, antioxidant, and neuroprotective activity. Accordingly, we proposed that MET would show antidepressant effects in patients with major depressive disorder (MDD) without other comorbidities. In this double-blind placebo-controlled study, 80 adult outpatients with MDD (DSM-IV criteria) and a Hamilton Depression Rating Scale (HAM-D) score >18 were randomized to receive fluoxetine 20 mg once daily plus placebo (n = 40) or fluoxetine 20 mg once daily plus MET 1000 mg once daily for 12 weeks. Patients were assessed by HAM-D score (weeks 0, 4, 8, and 12). The serum levels of TNF-α, IL-1β, IL-6, IGF-1, MDA, CRP, BDNF, and serotonin were measured before and after therapy. Mixed-effects model repeated-measures analysis of covariance was used to compare the HAM-D scores and the biological markers between the two groups. After 4, 8 and 12 weeks, patients in the MET group showed a statistically significant decline in HAM-D score relative to the placebo group (least squares mean difference [LSMD] -2.347, p = 0.000, LSMD -3.369, p = 0.000, and LSMD -3.454, p = 0.000, respectively). Response and remission rates were significantly higher in the MET group (89% and 81%, respectively) than in the placebo group (59% and 46%, respectively). Moreover, the MET group was superior in conserving the measured biological markers compared with the placebo group. Our findings suggest MET as a promising, effective, and safe short-term adjunctive approach in nondiabetic MDD patients. Trial registration ID: NCT04088448.

Alleviation of Depression by Glucagon-Like Peptide 1 Through the Regulation of Neuroinflammation, Neurotransmitters, Neurogenesis, and Synaptic Function

Depression has emerged as a major cause of mortality globally. Many studies have reported risk factors and mechanisms associated with depression, but it is as yet unclear how these findings can be applied to the treatment and prevention of this disorder. The onset and recurrence of depression have been linked to diverse metabolic factors, including hyperglycemia, dyslipidemia, and insulin resistance. Recent studies have suggested that depression is accompanied by memory loss as well as depressive mood. Thus, many researchers have highlighted the relationship between depressive behavior and metabolic alterations from various perspectives. Glucagon-like peptide-1 (GLP-1), which is secreted from gut cells and hindbrain areas, has been studied in metabolic diseases such as obesity and diabetes, and was shown to control glucose metabolism and insulin resistance. Recently, GLP-1 was highlighted as a regulator of diverse pathways, but its potential as the therapeutic target of depressive disorder was not described comprehensively. Therefore, in this review, we focused on the potential of GLP-1 modulation in depression.

The Safety, Efficacy, and Tolerability of Microbial Ecosystem Therapeutic-2 in People With Major Depression and/or Generalized Anxiety Disorder: Protocol for a Phase 1, Open-Label Study

BACKGROUND

The bidirectional signaling between the gut microbiota and the brain, known as the gut-brain axis, is being heavily explored in current neuropsychiatric research. Analyses of the human gut microbiota have shown considerable individual variability in bacterial content, which is hypothesized to influence brain function, and potentially mood and anxiety symptoms, through gut-brain axis communication. Preclinical and clinical research examining these effects suggests that fecal microbiota transplant (FMT) may aid in improving the severity of depression and anxiety symptoms by recolonizing the gastrointestinal (GI) tract with healthy bacteria. The microbial ecosystem therapeutic (ie, microbial ecosystem therapeutic-2 [MET-2]) used in this study is an alternative treatment to FMT, which comprises 40 different strains of gut bacteria from a healthy donor.

OBJECTIVE

The primary objective of this study is to assess subjective changes in mood and anxiety symptoms before, during, and after administration of MET-2. The secondary objectives of this study are to assess the changes in metabolic functioning and the level of repopulation of healthy gut bacteria, the safety and tolerability of MET-2, and the effects of early stress on biomarkers of depression/anxiety and the response to treatment.

METHODS

Adults experiencing depressive or anxiety symptoms will be recruited from the Kingston area. These participants will orally consume an encapsulated MET-2 once daily-containing 40 strains of purified and laboratory-grown bacteria from a single healthy donor-for 8 weeks, followed by a 2-week treatment-free follow-up period. Participants will undergo a series of clinical assessments measuring mood, anxiety, and GI symptoms using validated clinical scales and questionnaires. Molecular data will be collected from blood and fecal samples to assess metabolic changes, neurotransmitter levels, inflammatory markers, and the level of engraftment of the fecal samples that may predict outcomes in depression or anxiety.

RESULTS

Given the association between the gut bacteria and the risk factors of depression, we expect to observe an improvement in the severity of depressive and anxiety symptoms following treatment, and we expect that this improvement is mediated by the recolonization of the GI tract with healthy bacteria. The recruitment for this study has been completed, and the data obtained are currently being analyzed.

CONCLUSIONS

This is the first time MET-2 is being tested in psychiatric indications, specifically depression and anxiety. As such, this may be the first study to show the potential effects of microbial therapy in alleviating psychiatric symptoms as well as its safety and tolerability.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/17223.

Ketamine as an antidepressant: overview of its mechanisms of action and potential predictive biomarkers

Ketamine, a drug introduced in the 1960s as an anesthetic agent and still used for that purpose, has garnered marked interest over the past two decades as an emerging treatment for major depressive disorder. With increasing evidence of its efficacy in treatment-resistant depression and its potential anti-suicidal action, a great deal of investigation has been conducted on elucidating ketamine's effects on the brain. Of particular interest and therapeutic potential is the ability of ketamine to exert rapid antidepressant properties as early as several hours after administration. This is in stark contrast to the delayed effects observed with traditional antidepressants, often requiring several weeks of therapy for a clinical response. Furthermore, ketamine appears to have a unique mechanism of action involving glutamate modulation via actions at the N-methyl-D-aspartate (NMDA) and α -amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors, as well as downstream activation of brain-derived neurotrophic factor (BDNF) and mechanistic target of rapamycin (mTOR) signaling pathways to potentiate synaptic plasticity. This paper provides a brief overview of ketamine with regard to pharmacology/pharmacokinetics, toxicology, the current state of clinical trials on depression, postulated antidepressant mechanisms and potential biomarkers (biochemical, inflammatory, metabolic, neuroimaging sleep-related and cognitive) for predicting response to and/or monitoring of therapeutic outcome with ketamine.

Associations among peripheral and central kynurenine pathway metabolites and inflammation in depression

Kynurenine pathway (KP) metabolites are believed to be a link between inflammation and depression through effects on brain glutamate receptors. However, neither the relationship between plasma and cerebrospinal fluid (CSF) KP metabolites nor their association with inflammatory mediators is well-established in depression. Moreover, the clinical profile associated with combined activation of plasma inflammatory and kynurenine pathways is unknown. Accordingly, plasma and CSF-KP metabolites and inflammatory markers along with depressive symptoms and antidepressant treatment response were measured in 72 unmedicated depressed patients. Following bivariate analyses, component factors representing immune and kynurenine variables in the plasma and CSF were extracted and were used to examine directionality of associations in a path model. In addition, patients were clustered using individual markers that most accounted for the association between plasma immune and KP systems. Path analysis revealed a directional association extending from plasma inflammatory markers to plasma kynurenines, to CSF kynurenines. Among immune markers, plasma tumor necrosis factor (TNF) was robustly associated with plasma kynurenine (KYN) and KYN/tryptophan (TRP), which was in turn significantly associated with CSF KYN, kynurenic acid, and quinolinic acid. Clustering of patients based on plasma TNF and KYN/TRP yielded subgroups of high (N = 17) and low (N = 55) TNF-KYN/TRP groups. High TNF-KYN/TRP subjects exhibited greater depression severity, anhedonia, and treatment nonresponse. In conclusion, plasma-KP metabolites may mediate an inflammation-associated depressive symptom profile via CNS KP metabolites that can serve as a target for intervention at the level of inflammation, peripheral KYN metabolism, KYN transport to the brain, or effects of KP metabolites on glutamate receptors.

Proinflammatory Cytokines Predict Brain Metabolite Concentrations in the Anterior Cingulate Cortex of Patients With Bipolar Disorder

Bipolar disorder (BD) is a severe psychiatric illness characterized by abnormalities in the immune/inflammatory function and in brain metabolism. Evidences suggest that inflammation may affect the levels of brain metabolites as measured by single-proton magnetic resonance spectroscopy (¹H-MRS). The aim of the study was to investigate whether a wide panel of inflammatory markers (i.e., cytokines, chemokines, and growth factors) can predict brain metabolite concentrations of glutamate, myo-inositol, N-acetylaspartate, and glutathione in a sample of 63 bipolar patients and 49 healthy controls. Three cytokines influenced brain metabolite concentrations: IL-9 positively predicts glutamate, IL-1β positively predicts Myo-inositol, and CCL5 positively predicts N-acetylaspartate concentrations. Furthermore, patients showed higher concentrations of glutamate, Myo-inositol, and glutathione and lower concentrations of N-acetylaspartate in respect to healthy controls. Our results confirm that inflammation in BD alters brain metabolism, through mechanisms possibly including the production of reactive oxygen species and glia activation.