Shortened onset of action of antidepressants in major depression using acetylsalicylic acid augmentation: a pilot open-label study

The Role of Inflammation in Depression and Beyond: A Primer for Clinicians

PURPOSE OF REVIEW

We evaluate available evidence for the role of inflammation in depression. We reappraise literature involving systemic inflammation, neuroinflammation and neurotransmission and their association with depression. We review the connection between depression, autoimmunity and infectious diseases. We revise anti-inflammatory treatments used in depression.

RECENT FINDINGS

Peripheral inflammatory markers are present in a subset of patients with depression and can alter common neurotransmitters in this population but there is no clear causality between depression and systemic inflammation. Infectious conditions and autoimmune illnesses do not have a clear correlation with depression. Certain medications have positive evidence as adjunctive treatments in depression but studies are heterogenic, hence they are sparsely used in clinical settings. The current evidence does not fully support inflammation, infections or autoimmunity as possible etiologies of depression. The available studies have numerous confounders that obscure the findings. Anti-inflammatory agents may have potential for treatment of depression, but further research is needed to clarify their usefulness in routine clinical practice.

"Inflamed" depression: A review of the interactions between depression and inflammation and current anti-inflammatory strategies for depression

Depression is a common mental disorder, the effective treatment of which remains a challenging issue worldwide. The clinical pathogenesis of depression has been deeply explored, leading to the formulation of various pathogenic hypotheses. Among these, the monoamine neurotransmitter hypothesis holds a prominent position, yet it has significant limitations as more than one-third of patients do not respond to conventional treatments targeting monoamine transmission disturbances. Over the past few decades, a growing body of research has highlighted the link between inflammation and depression as a potential key factor in the pathophysiology of depression. In this review, we first summarize the relationship between inflammation and depression, with a focus on the pathophysiological changes mediated by inflammation in depression. The mechanisms linking inflammation to depression as well as multiple anti-inflammatory strategies are also discussed, and their efficacy and safety are assessed. This review broadens the perspective on specific aspects of using anti-inflammatory strategies for treating depression, laying the groundwork for advancing precision medicine for individuals suffering from "inflamed" depression.

Reviewing the neurobiology of electroconvulsive therapy on a micro- meso- and macro-level

BACKGROUND

Electroconvulsive therapy (ECT) remains the one of the most effective of biological antidepressant interventions. However, the exact neurobiological mechanisms underlying the efficacy of ECT remain unclear. A gap in the literature is the lack of multimodal research that attempts to integrate findings at different biological levels of analysis METHODS: We searched the PubMed database for relevant studies. We review biological studies of ECT in depression on a micro- (molecular), meso- (structural) and macro- (network) level.

RESULTS

ECT impacts both peripheral and central inflammatory processes, triggers neuroplastic mechanisms and modulates large scale neural network connectivity.

CONCLUSIONS

Integrating this vast body of existing evidence, we are tempted to speculate that ECT may have neuroplastic effects resulting in the modulation of connectivity between and among specific large-scale networks that are altered in depression. These effects could be mediated by the immunomodulatory properties of the treatment. A better understanding of the complex interactions between the micro-, meso- and macro- level might further specify the mechanisms of action of ECT.

Multi-omics reveals aspirin eugenol ester alleviates neurological disease

BACKGROUND

Exosomes play an essential role in maintaining normal brain function due to their ability to cross the blood-brain barrier. Aspirin eugenol ester (AEE) is a new medicinal compound synthesized by the esterification of aspirin with eugenol using the prodrug principle. Aspirin has been reported to have neuroprotective effects and may be effective against neurodegenerative diseases.

PURPOSE

This study wanted to investigate how AEE affected neurological diseases in vivo and in vitro.

EXPERIMENTAL APPROACH

A multi-omics approach was used to explore the effects of AEE on the nervous system. Gene and protein expression changes of BDNF and NEFM in SY5Y cells after AEE treatment were detected using RT-qPCR and Western Blot.

KEY RESULTS

The multi-omics results showed that AEE could regulate neuronal synapses, neuronal axons, neuronal migration, and neuropeptide signaling by affecting transport, inflammatory response, and regulating apoptosis. Exosomes secreted by AEE-treated Caco-2 cells could promote the growth of neurofilaments in SY5Y cells and increased the expression of BDNF and NEFM proteins in SY5Y cells. miRNAs in the exosomes of AEE-treated Caco-2 cells may play an important role in the activation of SY5Y neuronal cells.

CONCLUSIONS

In conclusion, AEE could play positive effects on neurological-related diseases.

Acetylsalicylic Acid and Mood Disorders: A Systematic Review

The effects of acetylsalicylic acid (ASA) on mood disorders (MD) and on inflammatory parameters in preclinical and clinical studies have not yet been comprehensively evaluated. The aim of this study was to systematically summarize the available knowledge on this topic according to PRISMA guidelines. Data from preclinical and clinical studies were analyzed, considering the safety and efficacy of ASA in the treatment of MD and the correlation of inflammatory parameters with the effect of ASA treatment. Twenty-one studies were included. Both preclinical and clinical studies found evidence indicating the safety and efficacy of low-dose ASA in the treatment of all types of affective episodes in MD. Observational studies have indicated a reduced risk of all types of affective episodes in chronic low-dose ASA users (HR 0.92, 95% CI: 0.88, 0.95, p < 0.0001). An association between ASA response and inflammatory parameters was found in preclinical studies, but this was not confirmed in clinical trials. Further long-term clinical trials evaluating the safety and efficacy of ASA in recurrent MD, as well as assessing the linkage of ASA treatment with inflammatory phenotype and cytokines, are required. There is also a need for preclinical studies to understand the exact mechanism of action of ASA in MD.

Current Perspectives on Pharmacological and Non-Pharmacological Interventions for the Inflammatory Mechanism of Unipolar Depression

Since depression remains a major public health issue there is a constant need for new and more efficient therapeutic strategies based on the mechanisms involved in the aetiology of depression. Thus, the pathogenic link between depression and inflammation is considered to play a potential key role in the development of such therapies. This review summarizes the results of various pharmacological (non-steroidal anti-inflammatory drugs, aspirin, cyclooxygenase inhibitors, cytokine inhibitors, corticosteroids, statins, minocycline, N-acetyl cysteine, omega-3 fatty acids and probiotics) and non-pharmacological interventions (electroconvulsive therapy, physical exercise and psychological therapy) and outlines their efficacy and discusses potential challenges. Both conventional and non-conventional anti-inflammatory drugs showed promising results according to the specific group of patients. The pre-existing pro-inflammatory status was, in most cases, a predictor for clinical efficacy and, in some cases, a correlation between clinical improvement and changes in various biomarkers was found. Some of the non-pharmacological interventions (physical exercise and electroconvulsive therapy) have also showed beneficial effects for depressive patients with elevated inflammatory markers. Treatments with anti-inflammatory action may improve clinical outcomes in depression, at least for some categories of patients, thus opening the way for a future personalised approach to patients with unipolar depression regarding the inflammation-related mechanism.

Effects of Dexamethasone and Pentoxifylline on Mania-like and Depression-like Behaviors in Rats

Several studies support the notion that inflammation plays a role in the pathophysiology and treatment approaches of psychiatric illnesses, particularly mood disorders. Congruently, classic anti-inflammatory drugs were found efficacious in randomized clinical trials of patients with mood disorders. Moreover, accumulating data indicate that psychotropic drugs exhibit some anti-inflammatory effects. This study was undertaken to examine the efficacy of dexamethasone (a potent corticosteroid) and pentoxifylline (a methylxanthine drug with proven anti-tumor necrosis factor-α inhibitory activity) in behavioral models in rats, which were treated intraperitoneally with either dexamethasone or pentoxifylline for two weeks and then subjected to a battery of behavioral tests. Treatment with pentoxifylline, but not dexamethasone, was associated with antidepressant-like and anti-manic-like effects. The beneficial behavioral effects of pentoxifylline were accompanied by a prominent reduction in pro-inflammatory mediator levels in the brain. For the first time, the current work proves the efficacy of pentoxifylline against both mania-like and depressive-like behaviors. These results suggest that pentoxifylline may be a promising therapeutic intervention for patients with mood disorders. Taking into account the excellent tolerability profile of pentoxifylline in humans, it is warranted to conduct randomized clinical trials to investigate its therapeutic efficacy in patients with psychiatric disorders.

Microglial Inflammatory-Metabolic Pathways and Their Potential Therapeutic Implication in Major Depressive Disorder

Increasing evidence supports the notion that neuroinflammation plays a critical role in the etiology of major depressive disorder (MDD), at least in a subset of patients. By virtue of their capacity to transform into reactive states in response to inflammatory insults, microglia, the brain's resident immune cells, play a pivotal role in the induction of neuroinflammation. Experimental studies have demonstrated the ability of microglia to recognize pathogens or damaged cells, leading to the activation of a cytotoxic response that exacerbates damage to brain cells. However, microglia display a wide range of responses to injury and may also promote resolution stages of inflammation and tissue regeneration. MDD has been associated with chronic priming of microglia. Recent studies suggest that altered microglial morphology and function, caused either by intense inflammatory activation or by senescence, may contribute to depression and associated impairments in neuroplasticity. In this context, modifying microglia phenotype by tuning inflammatory pathways might have important translational relevance to harness neuroinflammation in MDD. Interestingly, it was recently shown that different microglial phenotypes are associated with distinct metabolic pathways and analysis of the underlying molecular mechanisms points to an instrumental role for energy metabolism in shaping microglial functions. Here, we review various canonical pro-inflammatory, anti-inflammatory and metabolic pathways in microglia that may provide new therapeutic opportunities to control neuroinflammation in brain disorders, with a strong focus on MDD.

A Reciprocal Link Between Gut Microbiota, Inflammation and Depression: A Place for Probiotics?

Depression is a severe mental disorder that places a significant economic burden on public health. The reciprocal link between the trillions of bacteria in the gut, the microbiota, and depression is a controversial topic in neuroscience research and has drawn the attention of public interest and press coverage in recent years. Mounting pieces of evidence shed light on the role of the gut microbiota in depression, which is suggested to involve immune, endocrine, and neural pathways that are the main components of the microbiota-gut-brain axis. The gut microbiota play major roles in brain development and physiology and ultimately behavior. The bidirectional communication between the gut microbiota and brain function has been extensively explored in animal models of depression and clinical research in humans. Certain gut microbiota strains have been associated with the pathophysiology of depression. Therefore, oral intake of probiotics, the beneficial living bacteria and yeast, may represent a therapeutic approach for depression treatment. In this review, we summarize the findings describing the possible links between the gut microbiota and depression, focusing mainly on the inflammatory markers and sex hormones. By discussing preclinical and clinical studies on probiotics as a supplementary therapy for depression, we suggest that probiotics may be beneficial in alleviating depressive symptoms, possibly through immune modulation. Still, further comprehensive studies are required to draw a more solid conclusion regarding the efficacy of probiotics and their mechanisms of action.

Inflammation and serotonin deficiency in major depressive disorder: Molecular docking of antidepressant and antiinflammatory drugs to tryptophan and indoleamine 2,3-dioxygenases

The roles of the kynurenine pathway (KP) of tryptophan (Trp) degradation in serotonin deficiency in major depressive disorder (MDD) and the associated inflammatory state are considered in the present study. Using molecular docking in silico, we demonstrate binding of antidepressants to the crystal structure of tryptophan 2,3-dioxygenase (TDO), but not to indoleamine 2,3-dioxygenase (IDO). TDO is inhibited by a wide range of antidepressant drugs. The rapidly acting antidepressant ketamine does not dock to either enzyme, but may act by inhibiting kynurenine monooxygenase thereby antagonising glutamatergic activation to normalise serotonin function. Antidepressants with antiinflammatory properties are unlikely to act by direct inhibition of IDO, but may inhibit IDO induction by lowering levels of proinflammatory cytokines in immune-activated patients. Of 6 antiinflammatory drugs tested, only salicylate docks strongly to TDO and apart from celecoxib, the other 5 dock to IDO. TDO inhibition remains the major common property of antidepressants and TDO induction the most likely mechanism of defective serotonin synthesis in MDD.  TDO inhibition and increased free Trp availability by salicylate may underpin the antidepressant effect of aspirin and distinguish it from other nonsteroidal antiinflammatory drugs.  The controversial findings with IDO in MDD patients with an inflammatory state can be explained by IDO induction being overridden by changes in subsequent KP enzymes influencing glutamatergic function. The pathophysiology of MDD may be underpinned by the interaction of serotonergic and glutamatergic activities.

Antidepressant psychopharmacology: is inflammation a future target?

Raised inflammatory setpoints have been associated with major depression and its detrimental consequences on brain function, as they lead to increased production of cytokines, changes in gene expression and activated brain microglia. Three main lines of evidence support immune-inflammatory mechanisms as targets for the treatment of depression. First, higher inflammation hampers response to antidepressants, and effective antidepressant treatment decreases inflammation. Second, conventional antidepressants share immune-modulatory and anti-inflammatory properties, which could affect inflammation during the depression. Third, anti-inflammatory and immune-modulatory treatments proved superior to placebo in randomized controlled antidepressant trials. New targets and new pharmacologic treatment for immune-mediated inflammatory diseases have been identified and tested in several medical settings and interest is warranted for testing them as antidepressants.

Are Essential Trace Elements Effective in Modulation of Mental Disorders? Update and Perspectives

The emergence of mental disorders is associated with several risk factors including genetic and environmental susceptibility. A group of nutrients serves an especially important role in a number of essential neurodevelopmental processes through brain areas promoting the high degree of brain metabolism during early life, although almost all nutrients are needed. These include macronutrients and micronutrients (e.g., iron, magnesium, zinc, copper, selenium). Numerous nutritional psychiatry trials have been performed to examine the correlation of many individual nutrients with mental health, such as essential trace elements. The increased accumulation or lack of such components will facilitate an alternative metabolic pathway that can lead to many diseases and conditions of neurodevelopment. Mental functions have biochemical bases, so the impairment of such neurochemical mechanisms due to lack of trace elements can have mental effects. In psychological conditions such as depression, anxiety, schizophrenia, and autism, scientific studies demonstrate the putative role of trace element deficiency. Therefore, given the critical roles played by essential trace elements in the neurodevelopment and mental health, the effect of these elements' intake on the modulation of psychological functioning is reviewed.

Investigating the potential of fish oil as a nutraceutical in an animal model of early life stress

Background: Early life stress is a key predisposing factor for depression and anxiety disorders. Selective serotonin re-uptake inhibitors (SSRI) are frequently used as the first line of pharmacology treatment for depression but have several negative qualities, i.e. a delay or absence of effectiveness and negative side-effects. Therefore, there is a growing need for new nutraceutical-based strategies to blunt the effects of adverse-life events.Objectives: This study aimed to use the maternal separation model in rats to test the efficacy of fish oil dietary supplementation, on its own and in conjunction with the SSRI anti-depressant fluoxetine, as a treatment for depressive and anxiety-like symptoms associated with early life stress.Methods: Behavioural tests (open field test, elevated plus maze test and forced swim test) and biochemical markers (corticosterone, BDNF, brain fatty acids and short chain fatty acids) were used to analyse the effects of the dietary treatments. Gut microbial communities and relating metabolites (SCFA) were analysed to investigate possible changes in the microbiota-gut-brain axis.Results: Maternally separated rats showed depressive-like behaviours in the forced swim and open field tests. These behaviours were prevented significantly by fluoxetine administration and in part by fish oil supplementation. Associated biochemical changes reported include altered brain fatty acids, significantly lower plasma corticosterone levels (AUC) and reduced brain stem serotonin turnover, compared to untreated, maternally separated (MS) rats. Untreated MS animals had significantly lower ratios of SCFA producers such as Caldicoprobacteraceae, Streptococcaceae, Rothia, Lachnospiraceae_NC2004_group, and Ruminococcus_2, along with significantly reduced levels of total SCFA compared to non-separated animals. Compared to untreated MS animals, animals fed fish oil had significantly higher Bacteroidetes and Prevotellaceae and reduced levels of butyrate, while fluoxetine treatment resulted in significantly higher levels of Neochlamydia, Lachnoclostridium, Acetitomaculum and Stenotrophomonas and, acetate and propionate.Conclusion: Despite the limitations in extrapolating from animal behavioural data and the notable differences in pharmacokinetics between rodents and humans, the results of this study provide a further advancement into the understanding of some of the complex systems within which nutraceuticals and pharmaceuticals effect the microbiota-gut-brain axis.

Associations between Melatonin, Neuroinflammation, and Brain Alterations in Depression

Pro-inflammatory systemic conditions that can cause neuroinflammation and subsequent alterations in brain regions involved in emotional regulation have been suggested as an underlying mechanism for the pathophysiology of major depressive disorder (MDD). A prominent feature of MDD is disruption of circadian rhythms, of which melatonin is considered a key moderator, and alterations in the melatonin system have been implicated in MDD. Melatonin is involved in immune system regulation and has been shown to possess anti-inflammatory properties in inflammatory conditions, through both immunological and non-immunological actions. Melatonin has been suggested as a highly cytoprotective and neuroprotective substance and shown to stimulate all stages of neuroplasticity in animal models. The ability of melatonin to suppress inflammatory responses through immunological and non-immunological actions, thus influencing neuroinflammation and neurotoxicity, along with subsequent alterations in brain regions that are implicated in depression, can be demonstrated by the antidepressant-like effects of melatonin. Further studies that investigate the associations between melatonin, immune markers, and alterations in the brain structure and function in patients with depression could identify potential MDD biomarkers.

Augmentative Pharmacological Strategies in Treatment-Resistant Major Depression: A Comprehensive Review

Treatment resistant depression (TRD) is associated with poor outcomes, but a consensus is lacking in the literature regarding which compound represents the best pharmacological augmentation strategy to antidepressants (AD). In the present review, we identify the available literature regarding the pharmacological augmentation to AD in TRD. Research in the main psychiatric databases was performed (PubMed, ISI Web of Knowledge, PsychInfo). Only original articles in English with the main topic being pharmacological augmentation in TRD and presenting a precise definition of TRD were included. Aripiprazole and lithium were the most investigated molecules, and aripiprazole presented the strongest evidence of efficacy. Moreover, olanzapine, quetiapine, cariprazine, risperidone, and ziprasidone showed positive results but to a lesser extent. Brexpiprazole and intranasal esketamine need further study in real-world practice. Intravenous ketamine presented an evincible AD effect in the short-term. The efficacy of adjunctive ADs, antiepileptic drugs, psychostimulants, pramipexole, ropinirole, acetyl-salicylic acid, metyrapone, reserpine, testosterone, T3/T4, naltrexone, SAMe, and zinc cannot be precisely estimated in light of the limited available data. Studies on lamotrigine and pindolol reported negative results. According to our results, aripiprazole and lithium may be considered by clinicians as potential effective augmentative strategies in TRD, although the data regarding lithium are somewhat controversial. Reliable conclusions about the other molecules cannot be drawn. Further controlled comparative studies, standardized in terms of design, doses, and duration of the augmentative treatments, are needed to formulate definitive conclusions.

Cardiovascular Events After Partner Bereavement, What is the Role of Low Dose Aspirin and Beta-Blockers?

Bereavement due to loss of a partner is one of the most stressful life events, often leading to adverse physiological responses. Spousal loss has been associated with an increased morbidity and mortality, particularly from cardiovascular disease. Use of aspirin and/or beta adrenergic blockers have previously been suggested to play a role in cardiovascular risk associated with early bereavement. However, the available literature regarding this topic is limited. In this review article, we explore the potential beneficial role of aspirin and beta blockers in early bereavement. Our systematic review suggests that most studies have found aspirin and beta blockers to be beneficial in preventing adverse cardiovascular outcomes associated with early bereavement. Further randomized controlled long-term studies are warranted with adequate sample size to clearly establish the role of these medications on cardiovascular disease in late bereavement.

Efficacy and safety of pentoxifylline combination therapy in major depressive disorder: a randomized, double-blind, placebo-controlled clinical trial

In this randomized, double-blind, placebo-controlled clinical trial, we assessed the efficacy and safety of pentoxifylline combination therapy with sertraline in treatment of major depressive disorder (MDD). A total of 56 patients with MDD were assigned into two parallel groups to receive sertraline (100 mg/day) plus placebo or sertraline (100 mg/day) plus pentoxifylline (400 mg three times daily) for six weeks. Patients were evaluated with the Hamilton rating scale for depression (HAM-D) at baseline and weeks 2, 4 and 6. The sertraline plus pentoxifylline group demonstrated greater improvement in HAM-D scores from baseline to all three study time points (P = 0.013, 0.007 and 0.016 for week 2, 4 and 6, respectively). Response to treatment rate was also significantly higher in the sertraline plus pentoxifylline group compared to the sertraline plus placebo group at week 4 [57.1 vs. 21.4%, P = 0.013] and the study endpoint [96.4 vs. 57.1%, P = 0.001]. However, the remission rate, time to remission and time to treatment response did not show any significant difference between trial groups. Our findings support the efficacy and safety of pentoxifylline combination therapy in patients with MDD.

Childhood trauma determines different clinical and biological manifestations in patients with eating disorders

PURPOSE

There is a significant relationship between childhood trauma and the development of an eating disorder in adolescence or adulthood, possibly influenced by circulating levels of inflammatory parameters. The main objective is to identify and describe a subgroup of patients with eating disorders and a history of trauma in childhood or adolescence with differential clinical features.

METHODS

An observational study on a sample of 55 patients who met the diagnostic criteria for any DSM-5 eating disorder was carried out. Inflammatory parameters in white blood cells were examined. Patients underwent different assessments, including clinical and personality scales.

RESULTS

Patients with a history of trauma had higher scores in the delirious and narcissistic items of the Millon Clinical Multiaxial Inventory (MCMI-II) (p < 0.05) and a higher score in the paranoid item of the SCID-5 Personality Disorders Version (SCID-5-PD) (p < 0.05). Patients with distinguishing personality features were grouped according to the Childhood Trauma Questionnaire sexual subscale. Tumor necrosis alpha (TNF-α) showed a significant association with childhood trauma history.

CONCLUSIONS

There is a profile of patients with eating disorders who have increased activity in the inflammatory pathways that, if identified precociously, can benefit from specifically aimed interventions.

LEVEL OF EVIDENCE

Level V, observational study.

Brain-immune crosstalk in the treatment of major depressive disorder

A growing number of studies are pointing out the need for a conceptual shift from a brain-centered to a body-inclusive approach in mental health research. In this perspective, the link between the immune and the nervous system, which are deeply interconnected and continuously interacting, is one of the most important novel theoretical framework to investigate the biological bases of major depressive disorder and, more in general, mental illness. Indeed, depressed patients show high levels of inflammatory markers, administration of pro-inflammatory drugs triggers a depressive symptomatology and antidepressant efficacy is reduced by excessive immune system activation. A number of molecular and cellular mechanisms have been hypothesized to act as a link between the immune and brain function, thus representing potential pharmacologically targetable processes for the development of novel and effective therapeutic strategies. These include the modulation of the kynurenine pathway, the crosstalk between metabolic and inflammatory processes, the imbalance in acquired immune responses, in particular T cell responses, and the interplay between neural plasticity and immune system activation. In the personalized medicine approach, the assessment and regulation of these processes have the potential to lead, respectively, to novel diagnostic approaches for the prediction of treatment outcome according to the patient's immunological profile, and to improved efficacy of antidepressant compounds through immune modulation.

Postviral Depression

A previously healthy 68-year-old man rapidly developed a severe melancholic depression following influenza infection. There is an evolving understanding of the complex and possibly bidirectional relationship between depression and inflammation. We review the literature concerning this relationship in the context of viral infection and discuss possible implications for treatment.

Treatment-Resistant Depression Revisited: A Glimmer of Hope

Major Depressive Disorder (MDD) is a highly prevalent psychiatric disorder worldwide. It causes individual suffering, loss of productivity, increased health care costs and high suicide risk. Current pharmacologic interventions fail to produce at least partial response to approximately one third of these patients, and remission is obtained in approximately 30% of patients. This is known as Treatment-Resistant Depression (TRD). The burden of TRD exponentially increases the longer it persists, with a higher risk of impaired functional and social functioning, vast losses in quality of life and significant risk of somatic morbidity and suicidality. Different approaches have been suggested and utilized, but the results have not been encouraging. In this review article, we present new approaches to identify and correct potential causes of TRD, thereby reducing its prevalence and with it the overall burden of this disease entity. We will address potential contributory factors to TRD, most of which can be investigated in many laboratories as routine tests. We discuss endocrinological aberrations, notably, hypothalamic-pituitary-adrenal (HPA) axis dysregulation and thyroid and gonadal dysfunction. We address the role of Vitamin D in contributing to depression. Pharmacogenomic testing is being increasingly used to determine Single Nucleotide Polymorphisms in Cytochrome P450, Serotonin Transporter, COMT, folic acid conversion (MTHFR). As the role of immune system dysregulation is being recognized as potentially a major contributory factor to TRD, the measurement of C-reactive protein (CRP) and select immune biomarkers, where testing is available, can guide combination treatments with anti-inflammatory agents (e.g., selective COX-2 inhibitors) reversing treatment resistance. We focus on established and emerging test procedures, potential biomarkers and non-biologic assessments and interventions to apply personalized medicine to effectively manage treatment resistance in general and TRD specifically.

Drug repositioning for treatment-resistant depression: Hypotheses from a pharmacogenomic study

About 20-30% of patients with major depressive disorder (MDD) develop treatment-resistant depression (TRD) and finding new effective treatments for TRD has been a challenge. This study aimed to identify new possible pharmacological options for TRD. Genes in pathways included in predictive models of TRD in a previous whole exome sequence study were compared with those coding for targets of drugs in any phase of development, nutraceuticals, proteins and peptides from Drug repurposing Hub, Drug-Gene Interaction database and DrugBank database. We tested if known gene targets were enriched in TRD-associated genes by a hypergeometric test. Compounds enriched in TRD-associated genes after false-discovery rate (FDR) correction were annotated and compared with those showing enrichment in genes associated with MDD in the last Psychiatric Genomics Consortium genome-wide association study. Among a total of 15,475 compounds, 542 were enriched in TRD-associated genes (FDR p < .05). Significant results included drugs which are currently used in TRD (e.g. lithium and ketamine), confirming the rationale of this approach. Interesting molecules included modulators of inflammation, renin-angiotensin system, proliferator-activated receptor agonists, glycogen synthase kinase 3 beta inhibitors and the rho associated kinase inhibitor fasudil. Nutraceuticals, mostly antioxidant polyphenols, were also identified. Drugs showing enrichment for TRD-associated genes had a higher probability of enrichment for MDD-associated genes compared to those having no TRD-genes enrichment (p = 6.21e-55). This study suggested new potential treatments for TRD using a in silico approach. These analyses are exploratory only but can contribute to the identification of drugs to study in future clinical trials.

Inflammation, Hippocampal Volume, and Therapeutic Outcome following Electroconvulsive Therapy in Depressive Patients: A Pilot Study

INTRODUCTION

Electroconvulsive therapy (ECT) influences the concentration of peripheral inflammatory markers, such as interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). In which way this immune effect contributes to the impact of ECT on the central nervous system in depression remains unknown.

OBJECTIVE

The aim of this study was to examine whether the hippocampal volumetric increase in depressed patients treated with ECT is related to changes in peripheral IL-6 and TNF-α levels.

METHODS

IL-6 and TNF-α plasma levels were measured in 62 patients 1 week before and after an acute course of ECT. Hippocampal volumes were analyzed in a magnetic resonance imaging (MRI) subsample of 13 patients at the same time points.

RESULTS

A significant decrease in IL-6 levels was observed in the total sample and a significant increase in hippocampal volume in the MRI subsample. The reduction of peripheral IL-6 correlated with an increase in total hippocampal volume. A more limited decrease of TNF-α correlated with a more limited increase of both the total and left hippocampus volumes.

CONCLUSION

This pilot study is the first to highlight the link between peripheral immune changes and hippocampal volume increase following ECT. Further research is required to conclude whether ECT indeed exerts its central effect on the brain via changes of peripheral inflammatory markers.

Gender dysphoria: prejudice from childhood to adulthood, but no impact on inflammation. A cross-sectional controlled study

INTRODUCTION

Gender dysphoria (GD) is characterized by a marked incongruence between experienced gender and one's gender assigned at birth. Transsexual individuals present a higher prevalence of psychiatric disorders when compared to non-transsexual populations, and it has been proposed that minority stress, i.e., discrimination or prejudice, has a relevant impact on these outcomes. Transsexuals also show increased chances of having experienced maltreatment during childhood. Interleukin (IL)-1β, IL-6, IL-10 and tumor necrosis factor-alpha (TNF-α) are inflammatory cytokines that regulate our immune system. Imbalanced levels in such cytokines are linked to history of childhood maltreatment and psychiatric disorders. We compared differences in IL-1β, IL-6, IL-10 and TNF-α levels and exposure to traumatic events in childhood and adulthood in individuals with and without GD (DSM-5).

METHODS

Cross-sectional controlled study comparing 34 transsexual women and 31 non-transsexual men. They underwent a thorough structured interview, assessing sociodemographic information, mood and anxiety symptoms, childhood maltreatment, explicit discrimination and suicidal ideation. Inflammatory cytokine levels (IL-1β, IL-6, IL-10 and TNF-α) were measured by multiplex immunoassay.

RESULTS

Individuals with GD experienced more discrimination (p = 0.002) and childhood maltreatment (p = 0.046) than non-transsexual men. Higher suicidal ideation (p < 0.001) and previous suicide attempt (p = 0.001) rates were observed in transsexual women. However, no differences were observed in the levels of any cytokine.

CONCLUSIONS

These results suggest that transsexual women are more exposed to stressful events from childhood to adulthood than non-transsexual men and that GD per se does not play a role in inflammatory markers.

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.

Cyclooxygenase Inhibition Safety and Efficacy in Inflammation-Based Psychiatric Disorders

According to the World Health Organization, the major psychiatric and neurodevelopmental disorders include major depression, bipolar disorder, schizophrenia, and autism spectrum disorder. The potential role of inflammation in the onset and progression of these disorders is increasingly being studied. The use of non-steroidal anti-inflammatory drugs (NSAIDs), well-known cyclooxygenase (COX) inhibitors, combined with first-choice specific drugs have been long investigated. The adjunctive administration of COX inhibitors to classic clinical treatments seems to improve the prognosis of people who suffer from psychiatric disorders. In this review, a broad overview of the use of COX inhibitors in the treatment of inflammation-based psychiatric disorders is provided. For this purpose, a critical analysis of the use of COX inhibitors in the last ten years of clinical trials of the major psychiatric disorders was carried out.

Effect of Aspirin vs Placebo on the Prevention of Depression in Older People: A Randomized Clinical Trial

IMPORTANCE

Depression is associated with increased inflammation, which may precede its onset, especially in older people. Some preclinical data suggest potential antidepressant effects of aspirin, supported by limited observational data suggesting lower rates of depression in individuals treated with aspirin. There currently appears to be no evidence-based pharmacotherapies for the primary prevention of depression.

OBJECTIVE

To determine whether low-dose aspirin (100 mg) reduces the risk of depression in healthy older adults.

DESIGN, SETTING, AND PARTICIPANTS

This double-blinded, placebo-controlled randomized clinical trial was a substudy of the Aspirin in Reducing Events in the Elderly (ASPREE) trial, which examined if aspirin increased healthy life span, defined as survival free of dementia and disability. The prespecified secondary outcome was depression. Individuals of all races/ethnicities older than 70 years in Australia, as well as white individuals older than 70 years and black and Hispanic individuals older than 65 years in the United States, were included.

INTERVENTIONS

Participants were randomized to aspirin (100 mg daily) or placebo, with a median (interquartile range) follow-up of 4.7 (3.5-5.6) years.

MAIN OUTCOMES AND MEASURES

The primary outcome was a proxy measure of major depressive disorder defined as a score of 8 or more on the Center for Epidemiologic Studies Depression 10-item (CES-D-10) scale.

RESULTS

Of the 19 114 participants enrolled in the trial, 9525 received aspirin and 9589 received a placebo. The mean (SD) age was 75.2 (4.0) years in the aspirin group and 75.1 (4.5) years in the placebo group; 9531 (56.4%) were women. Participants' demographics and clinical characteristics at baseline were similar between groups. A total of 79 886 annual CES-D-10 measurements were taken, with a mean of 4.2 measurements per participant. There were no significant differences at annual visits in the proportions of CES-D-10 scores of 8 or more between the aspirin and placebo groups. The incidence rate of new CES-D-10 scores of 8 or more was 70.4 events per 1000 person-years in the aspirin group and 69.1 in the placebo group (hazard ratio, 1.02 [95% CI, 0.96-1.08]; P = .54).

CONCLUSIONS AND RELEVANCE

Low-dose aspirin did not prevent depression in this large-scale study of otherwise healthy older adults.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT01038583.

Reductions in anti-inflammatory gut bacteria are associated with depression in a sample of young adults

We assessed the gut microbiota of 90 American young adults, comparing 43 participants with major depressive disorder (MDD) and 47 healthy controls, and found that the MDD subjects had significantly different gut microbiota compared to the healthy controls at multiple taxonomic levels. At the phylum level, participants with MDD had lower levels of Firmicutes and higher levels of Bacteroidetes, with similar trends in the at the class (Clostridia and Bacteroidia) and order (Clostridiales and Bacteroidales) levels. At the genus level, the MDD group had lower levels of Faecalibacterium and other related members of the family Ruminococcaceae, which was also reduced relative to healthy controls. Additionally, the class Gammaproteobacteria and genus Flavonifractor were enriched in participants with MDD. Accordingly, predicted functional differences between the two groups include a reduced abundance of short-chain fatty acid production pathways in the MDD group. We also demonstrated that the magnitude of taxonomic changes was associated with the severity of depressive symptoms in many cases, and that most changes were present regardless of whether depressed participants were taking psychotropic medications. Overall, our results support a link between MDD and lower levels of anti-inflammatory, butyrate-producing bacteria, and may support a connection between the gut microbiota and the chronic, low-grade inflammation often observed in MDD patients.

State-of-the-Art: Inflammatory and Metabolic Markers in Mood Disorders

Mounting evidence highlights the involvement of inflammatory/immune systems and their relationships with neurotransmitters and different metabolic processes in mood disorders. Nevertheless, there is a general agreement that available findings are still inconclusive. Therefore, further investigations are required, aimed at deepening the role of possible alterations of biomarkers in the pathophysiology of mood disorders that might lead to more focused and tailored treatments. The present study is a comprehensive review on these topics that seem to represent intriguing avenues for the development of real innovative therapeutic strategies of mood disorders.

The association between aspirin use and depression: a systematic review and meta-analysis of observational studies

PURPOSE

Many clinical trials and observational studies have been conducted under the premise that the anti-inflammatory effect of aspirin may prevent depression. These studies, however, showed inconsistent results. To inspect the association between aspirin use and depression, we conducted a meta-analysis of observational studies.

METHODS

In August 2019, two authors independently searched PubMed, EMBASE, and PsycINFO to retrieve observational epidemiological studies presenting an association between aspirin use and depression. Case-control and cohort studies were included, and odds ratios (ORs) or relative risks (RRs) with 95% confidence intervals (CIs) for the risk of depression were estimated using a random-effects model. In addition, number needed to harm (NNH) was calculated to measure the rates of depression.

RESULTS

In total, 12 observational studies-five case-control studies and seven prospective cohort studies-were included in this meta-analysis. The random-effects model demonstrated a significant association between aspirin use and depression (OR/RR 1.10; 95% CI: 1.05-1.16) with insignificant heterogeneity (I² = 23.3%). The risk estimates of depression from prospective cohort studies were similar (RR 1.11; 95% CI: 1.08-1.14), and heterogeneity was not observed (I² = 0.0%). In the subgroup meta-analysis, a duration of aspirin use ≥5 years and a dosage ≥500 mg daily were also associated with depression. The NNH for depression with aspirin use >5 years was 103 (95% CI 91-111) indicating that observed event is rare.

CONCLUSIONS

Aspirin use was associated with depression in the present meta-analysis. One of the major limitations is the lack of detail and consistency with respect to exposure verification in the included papers. Another limitation is the lack of randomized controlled studies and prospective cohort studies.

Targeting Inflammatory-Mitochondrial Response in Major Depression: Current Evidence and Further Challenges

The prevalence of psychiatric disorders has increased in recent years. Among existing mental disorders, major depressive disorder (MDD) has emerged as one of the leading causes of disability worldwide, affecting individuals throughout their lives. Currently, MDD affects 15% of adults in the Americas. Over the past 50 years, pharmacotherapy, psychotherapy, and brain stimulation have been used to treat MDD. The most common approach is still pharmacotherapy; however, studies show that about 40% of patients are refractory to existing treatments. Although the monoamine hypothesis has been widely accepted as a molecular mechanism to explain the etiology of depression, its relationship with other biochemical phenomena remains only partially understood. This is the case of the link between MDD and inflammation, mitochondrial dysfunction, and oxidative stress. Studies have found that depressive patients usually exhibit altered inflammatory markers, mitochondrial membrane depolarization, oxidized mitochondrial DNA, and thus high levels of both central and peripheral reactive oxygen species (ROS). The effect of antidepressants on these events remains unclear. Nevertheless, the effects of ROS on the brain are well known, including lipid peroxidation of neuronal membranes, accumulation of peroxidation products in neurons, protein and DNA damage, reduced antioxidant defenses, apoptosis induction, and neuroinflammation. Antioxidants such as ascorbic acid, tocopherols, and coenzyme Q have shown promise in some depressive patients, but without consensus on their efficacy. Hence, this paper provides a review of MDD and its association with inflammation, mitochondrial dysfunction, and oxidative stress and is aimed at thoroughly discussing the putative links between these events, which may contribute to the design and development of new therapeutic approaches for patients.

Bexarotene Improve Depression-Like Behaviour in Mice by Protecting Against Neuro-inflammation and Synaptic Damage

The growing number of evidences suggest that neuroinflammation and synaptic damage are closely related to the onset of depression. Bexarotene (Bex), a retinoid X receptor agonist, is an U.S. Food and Drug Administration-approved drug for the treatment of cutaneous T-cell lymphoma that has recently been reported to have anti-inflammatory and neuroprotective effects in several models of neurological disease including Parkinson's disease, Alzheimer's disease, and so forth. However, the effect of Bex on depression remains unclear. In this study, we investigated effect of Bex on depression-like behaviour in mice induced by lipopolysaccharide (LPS) or corticosterone (CORT). Our results showed that treatment with Bex for 15 days significantly improved LPS-induced depression-like behaviour in social interaction test and CORT-induced depression-like behaviour in forced swimming test and tail suspension test in mice. We found that the Bex treatment depressed the increase in the number of activated microglia and astrocytes in the frontal cortex, and the increase in the levels of inflammatory cytokines TNF-α, IL-1β and IL-6 in LPS-injected mice. Furthermore, Bex treatment also rescued the decrease in the expression of BDNF, and inhibition of CREB/BDNF/ERK pathway, and improved the expression of synaptic related protein in CORT-induced mice. Based on these results, it is possible that Bex reversed depression-like behaviour in mice by reducing neuroinflammation and protecting against synaptic damage induced by LPS or CORT.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

TRIAL REGISTRATION

Clinicaltrials.gov ID: NCT01479829.

Electroacupuncture Relieves LPS-Induced Depression-Like Behaviour in Rats Through IDO-Mediated Tryptophan-Degrading Pathway

BACKGROUND

Neuroinflammation is an important pathological mechanism of depression that leads to an increase in indoleamine-2,3-dioxygenase (IDO) activity and NMDAR activation. This study aimed to observe the effects of electroacupuncture on depression-like behaviour in lipopolysaccharide (LPS)-treated rats and the underlying mechanism.

METHODS

Wistar rats were intraperitoneally administered LPS (0.5 mg/kg) for 7 consecutive days to establish a depression model. Electroacupuncture treatment was administered 1 hour after daily LPS injection. The open field test (OFT), forced swimming test (FST), and sucrose preference test (SPT) were used to evaluate the depressive-like behaviours. IL-1β, IL-6, and TNF-α levels were determined by enzyme-linked immunosorbent assay (ELISA); Trp, 5-hydroxytryptamine (5-HT), kynurenine (Kyn) and quinolinic acid (Quin) were detected by ultra-high-performance liquid chromatography-tandem mass spectrometry; and N-methyl-D-aspartate receptor (NMDAR) protein and mRNA were assessed by Western blot and real-time qPCR.

RESULTS

The results showed that electroacupuncture treatment successfully corrected LPS-induced depressive-like behaviour, reduced the inflammatory factor (IL-1β, IL-6 and TNF-α) levels in the blood and hippocampus, prevented IDO over-activation and recovered NR2B expression after challenge by LPS.

CONCLUSION

Electroacupuncture treatment provided protection against LPS-induced depressive-like behaviour, and the associated mechanisms may be related to inhibiting the inflammatory response, regulating the IDO-mediated tryptophan-degrading pathway, and inhibiting NR2B activation.

Depression as an Immunometabolic Disorder: Exploring Shared Pharmacotherapeutics with Cardiovascular Disease

Modern times have seen depression and cardiovascular disease (CVD) become notorious public health concerns, corresponding to alarming proportions of morbidity, mortality, decreased quality of life, and economic costs. Expanding comprehension of the pathogenesis of depression as an immunometabolic disorder has identified numerous pathophysiologic phenomena in common with CVD, including chronic inflammation, insulin resistance, and oxidative stress. These shared components could be exploited to offer improved alternatives in the joint management of these conditions. Abundant preclinical and clinical data on the impact of established treatments for CVD in the management of depression have allowed for potential candidates to be proposed for the joint management of depression and CVD as immunometabolic disorders. However, a large proportion of the clinical investigation currently available exhibits marked methodological flaws which preclude the formulation of concrete recommendations in many cases. This situation may be a reflection of pervasive problems present in clinical research in psychiatry, especially pertaining to study homogeneity. Therefore, further high-quality research is essential in the future in this regard.

An immune gate of depression - Early neuroimmune development in the formation of the underlying depressive disorder

The prevalence of depression worldwide is increasing from year to year and constitutes a serious medical, economic and social problem. Currently, despite multifactorial risk factors and pathways contributing to depression development, a significant aspect is attributed to the inflammatory process. Cytokines are considered a factor activating the kynurenine pathway, which leads to the exhaustion of tryptophan in the tryptophan catabolite (TRYCAT) pathway. This results in the activation of potentially neuroprogressive processes and also affects the metabolism of many neurotransmitters. The immune system plays a coordinating role in mediating inflammatory process. Beginning from foetal life, dendritic cells have the ability to react to bacterial and viral antigens, stimulating T lymphocytes in a similar way to adult cells. Cytotoxicity in the prenatal period shapes the predisposition to the development of depression in adult life. Allostasis, i.e. the ability to maintain the body's balance in the face of environmental adversity through changes in its behaviour or physiology, allows the organism to survive but its consequences may be unfavourable if it lasts too long. As a result, Th lymphocytes, in particular T helper 17 cells, which play a central role in the immunity of the whole body, contribute to the development of both autoimmune diseases and psychiatric disorders including depression, as well as have an impact on the differentiation of T CD4+ cells into Th17 cells in the later development of the child's organism, which confirms the importance of the foetal period for the progression of depressive disorders.

Roles of Toll-like receptor 2/4, monoacylglycerol lipase, and cyclooxygenase in social defeat stress-induced prostaglandin E2 synthesis in the brain and their behavioral relevance

Inflammation in the brain and periphery has been associated with stress-related pathology of mental illness. We have shown that prostaglandin (PG) E₂, an arachidonic acid-derived lipid mediator, and innate immune receptors Toll-like receptor (TLR) 2/4 are crucial for repeated stress-induced behavioral changes in rodents. However, how the stress induces PGE₂ synthesis in the brain and whether TLR2/4 are involved in the PGE₂ synthesis remain unknown. Using mice lacking TLR2 and TLR4 in combination, here we show that social defeat stress (SDS) induced the PGE₂ synthesis in subcortical, but not cortical, tissues in a TLR2/4-dependent manner. It is known that PGE₂ in the brain is mainly derived by monoacylglycerol lipase (MAGL)-mediated conversion of endocannabinoid 2-arachidonoylglycerol to free-arachidonic acid, a substrate for cyclooxygenase (COX) for PGE₂ synthesis. We found that TLR2/4 deletion reduced the mRNA expression of MAGL and COX1 in subcortical tissues after repeated SDS. Perturbation of MAGL and COX1 as well as COX2 abolished SDS-induced PGE₂ synthesis in subcortical tissues. Furthermore, systemic administration of JZL184, an MAGL inhibitor, abolished repeated SDS-induced social avoidance. These results suggest that SDS induces PGE₂ synthesis in subcortical regions of the brain via the MAGL-COX pathway in a TLR2/4-dependent manner, thereby leading to social avoidance.

Celecoxib, ibuprofen, and indomethacin alleviate depression-like behavior induced by interferon-alfa in mice

Background Interferon-α (IFNα) therapy causes psychiatric side effects, including depression that may result in poor compliance of therapy. It is important to find alternative therapies for the prevention of IFNα induced depression. Non-steroidal anti-inflammatory drugs (NSAIDs) have been useful in depressive disorder. Therefore the effects of celecoxib, ibuprofen, and indomethacin were evaluated following IFNα-induced depression in mice. Methods Male albino mice weighing 26 ± 2 g were used. Depression was induced by IFNα (16 × 105 IU/kg, SC) for six consecutive days. Animals were first subject to the locomotor test, then the splash test and finally the forced swimming test (FST) on the 7th day. The NSAIDs were administered (IP) either one single dose before the test, or simultaneously with IFNα. Results locomotor activity was only impaired by ibuprofen high dose (75 mg/kg), thus it was not further evaluated. Following IFNα therapy depression-like behaviors were observed; significant changes during the splash test (grooming time 24 ± 7 sec vs. control 63 ± 7 sec), the FST (immobility time 166  ± 15 sec vs. control 128  ± 6 sec), and sucrose preference reduced to 64 ± 0.8%. The NSAIDs noticeably reduced the immobility time in FST, while grooming time was increased. Celecoxib and indomethacin single doses were effective while ibuprofen showed better antidepressant effects when it was administered along with IFNα. Conclusions The NSAIDs were able to prevent IFNα induced depression in mice. NSAIDs administration with IFNα does not interfere with clinical benefit effects of IFNα and they could also be useful to prevent IFNα psychiatric side effects, thus further clinical trials are suggested.

Treating psychiatric symptoms and disorders with non-psychotropic medications

A few drugs prescribed in internal medicine, ie, non-psychotropic drugs, can be used to treat certain neuropsychiatric disorders. For most of these situations, the level of evidence remains low. But when sufficient data becomes available, these molecules are then included in official guidelines for the treatment of neuropsychiatric disorders. In this article we review interesting drugs which may be relevant from an evidence-based medicine point of view, and could become part of psychiatric practice in the future.


The role of inflammation and the gut microbiome in depression and anxiety

The study of the gut microbiome has increasingly revealed an important role in modulating brain function and mental health. In this review, we underscore specific pathways and mechanisms by which the gut microbiome can promote the development of mental disorders such as depression and anxiety. First, we review the involvement of the stress response and immune system activation in the development of depression and anxiety. Then, we examine germ-free murine models used to uncover the role of the gut microbiome in developing and modulating pertinent activity in the brain and the immune system. We also document multiple pathways by which stress-induced inflammation harms brain function and ultimately affects mental health, and review how probiotic and prebiotic treatments have shown to be beneficial. Lastly, we provide an overview of gut microbiome-derived compounds (short-chain fatty acids, tryptophan catabolites, microbial pattern recognition) and related mechanisms (vagal nerve activity and fecal microbiota transplants) involved in mediating the influence of the gut microbiome to mental health. Overall, a picture of the gut microbiome playing a facilitating role between stress response, inflammation, and depression, and anxiety is emerging. Future research is needed to firmly establish the microbiome's causal role, to further elucidate the mechanisms by which gut microbes influence brain function and mental health, and to possibly develop treatments that improve mental health through microbiotic targets.

Baseline serum C-reactive protein levels may predict antidepressant treatment responses in patients with major depressive disorder

BACKGROUND

Inflammation has been shown previously to predict antidepressant treatment response. This retrospective study was conducted to test if the baseline serum C-reactive protein (CRP) levels could predict antidepressant treatment responses in a Chinese sample.

METHODS

75 adult inpatients (26 male, 49 female) with major depressive disorder (MDD) diagnosed according to DSM-5 were included in this study. Sociodemographic and clinical features, baseline CRP levels, 17-item Hamilton Depression Rating Scale (HDRS-17) and Hamilton Anxiety Rating Scale (HARS) scores assessed at baseline and weeks 1, 2, 3 and 4 were then collected. Afterwards patients were divided into two groups: the low CRP group (baseline CRP < 1 mg/L, n = 47) and the high CRP group (baseline CRP ≥ 1 mg/L, n = 28). Depression severity and treatment response were compared between the two groups.

RESULTS

Repeated-measures ANOVA showed a significant group * assessments interaction in HDRS-17 scores (F = 4.754; p = 0.005). Post-hoc test showed that the two groups differed in HDRS-17 scores at week 4 (F = 6.698; p = 0.012), with the low CRP group having lower HDRS-17 scores than the high CRP group. Moreover, the low CRP group exhibited higher percent reduction in HDRS-17 scores at week 3 (F = 5.016; p = 0.028) and week 4 (F = 9.865; p = 0.003) as compared to the high CRP group. Cox proportional hazard model showed that the remission rate was higher in the low CRP group (p = 0.010).

LIMITATIONS

Patients received uncontrolled antidepressant therapy and the sample size was limited.

CONCLUSIONS

Baseline serum CRP levels may predict antidepressant treatment responses in patients with MDD and patients with higher levels of CRP were less likely to get remission.

Effects of Aspirin in Rats With Ouabain Intracerebral Treatment-Possible Involvement of Inflammatory Modulation?

Bipolar disorder (BD) is a chronic and refractory disease with high probability of morbidity and mortality. Although epidemiological studies have established a strong association between BD and immune dysfunction, the precise etiology is still debatable, and the underpinning mechanism remains poorly investigated and understood. In the present study, manic-like symptoms of BD were induced in rats after intracerebroventricular administration of ouabain. Aspirin, a commonly used anti-inflammatory agent, was used to treat the induced manic-like symptoms and inflammation. Concentrations of a spectrum of inflammatory cytokines were examined by enzyme-linked immunosorbent assay in both plasma and brain tissues, and expression of Toll-like receptors 3 and 4 were determined in rat brains. Locomotor activity was monitored with open-field test to assess the effects of ouabain challenge and to evaluate the treatment efficacy of aspirin. Ouabain administration recapitulated many mania-like features such as increased stereotypic counts, traveling distance in open-field test, and decreased expression of brain-derived neurotrophic factor, interferon gamma, and Toll-like receptor 3, which were frequently found in patients with BD. These abnormalities could be partially reversed by aspirin. Our findings suggest that aspirin could be used as a promising adjunctive therapy for BD.

International Union of Basic and Clinical Pharmacology CIV: The Neurobiology of Treatment-resistant Depression: From Antidepressant Classifications to Novel Pharmacological Targets

Major depressive disorder is one of the most prevalent and life-threatening forms of mental illnesses and a major cause of morbidity worldwide. Currently available antidepressants are effective for most patients, although around 30% are considered treatment resistant (TRD), a condition that is associated with a significant impairment of cognitive function and poor quality of life. In this respect, the identification of the molecular mechanisms contributing to TRD represents an essential step for the design of novel and more efficacious drugs able to modify the clinical course of this disorder and increase remission rates in clinical practice. New insights into the neurobiology of TRD have shed light on the role of a number of different mechanisms, including the glutamatergic system, immune/inflammatory systems, neurotrophin function, and epigenetics. Advances in drug discovery processes in TRD have also influenced the classification of antidepressant drugs and novel classifications are available, such as the neuroscience-based nomenclature that can incorporate such advances in drug development for TRD. This review aims to provide an up-to-date description of key mechanisms in TRD and describe current therapeutic strategies for TRD before examining novel approaches that may ultimately address important neurobiological mechanisms not targeted by currently available antidepressants. All in all, we suggest that drug targeting different neurobiological systems should be able to restore normal function but must also promote resilience to reduce the long-term vulnerability to recurrent depressive episodes.

Development of Fangjiomics for Systems Elucidation of Synergistic Mechanism Underlying Combination Therapy

The rapid development of omics technology provides an opportunity for fulfilling the understanding of the synergistic mechanism of combination therapy. However, a systems theory to analyze synergy remains an ongoing challenge. Fangjiomics is a novel systems science based on a holistic theory integrated with reductionism which has been utilized to systematically elucidate the synergistic mechanisms underlying combination therapy using multi-target-, pathway- or network-based quantitative methods. Besides, our ability to understand the polyhierarchical structure in synergy is driven based on multi-level omics data fusion in Fangjiomics. According to the basic principle of “Jun-Chen-Zuo-Shi”, further global integration across various omics platforms and phenotype-driven quantitative multi-scale modeling would accelerate development in Fangjiomics-based dissection of synergy in multi-drug combination therapies.

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Fangjiomics is a novel systems science based on a holistic theory integrated with reductionism.

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We developed the pathway-based analysis of synergistic mechanisms in Fangjiomics.

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The theory of network-based synergistic targets is proposed in Fangjiomics.

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The hierarchical relationship of synergy in multilevel omics is dissected in Fangjiomics.

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The principle of “Jun-Chen-Zuo-Shi” is proposed to accelerate the development in Fangjiomics-based dissection of synergy.

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.

Gentiopicroside abrogates lipopolysaccharide-induced depressive-like behavior in mice through tryptophan-degrading pathway

Targeting neuroinflammatory disturbances has been acknowledged as a potential strategy for treatment of depressive disorder in humans. Over-activation of tryptophan-degrading pathway by pro-inflammatory cytokines resulted in N-methyl-d-aspartate (NMDA)-mediated excitotoxicity, which is implicated in pathophysiology of depression. Gentiopicroside (Gent) has powerful anti-inflammatory property and exhibits promising antidepressant effect in an animal model of pain/depression dyad by down-regulating GluN2B-containing NMDA receptors. Therefore, the present study aimed to investigate the ability of Gent to abolish depressive-like behavior induced by lipopolysaccharide (LPS) in mice. Acute administration of LPS (0.5 mg/kg, i.p.) increased immobility time in both forced swimming test (FST) and tail suspension test (TST) without affecting spontaneous locomotor activity, indicative of depressive-like behavior. Gent (50 mg/kg, i.p.) administered once a day for three consecutive days prevented the development of depressive-like behavior induced by LPS. The antidepressant-like effect was paralleled with restoration of LPS-induced alterations in brain inflammatory mediators (i.e. IL-1β and TNF-α). In addition, Gent prevented over-activation of indoleamine 2,3-double oxygen enzyme (IDO) and recovered GluN2B subunit expression in the PFC challenged by LPS. In conclusion, our results suggested that Gent pretreatment provided protection against LPS-induced depressive-like behavior and the effect appeared to be demonstrated, at least partially, by blocking various steps of tryptophan-degrading pathway.