TNFalpha signaling in depression and anxiety: behavioral consequences of individual receptor targeting

Deletion of filamin A-interacting protein (FILIP) results in a weak grip strength and abnormal responses to nociceptive stimulation

Filamin A-interacting protein (FILIP in mice, FILIP1 in humans) was first identified as a protein that negatively controls neuronal migration in rodents, and was subsequently demonstrated to be pivotal for the development of the neocortex. In the previous study, we generated FILIP knockout mice to investigate the in vivo functions of FILIP in cortical development. Since FILIP mRNA is widely expressed in the body, we systematically examined FILIP-knockout mice to determine the functions of FILIP throughout the body. Our results showed that FILIP-knockout mice exhibited weak grip strength and sensory abnormalities. Interestingly, we also found that FILIP was expressed in a subset of neurons in the dorsal root ganglion (DRG). Recent research has reported that FILIP1 mutations lead to severe neurological and musculoskeletal abnormalities, resulting in the proposal of a new disease entity, termed FILIP1opathy. It is expected that our FILIP-knockout mice could be used as a model for the pathological investigation of FILIP1opathy.

A systematic approach to identify gaps in neuroimmunology: TNF-α and fear learning deficits, a worked example

BACKGROUND

The pathophysiology of several neurodegenerative and neuropsychiatric disorders is linked to an altered immune system. However, it is often unclear how the immune system specifically affects these disorders since neuroimmune interactions are very complex. In this paper, we introduce an adjusted version of the adverse outcome pathway (AOP) approach from toxicology to the field of neuroimmunology. A review of the effect of TNF-α on fear learning deficits is used as a worked example to demonstrate how an AOP approach can help identify gaps of knowledge and crucial steps in the pathophysiology of neuroimmunological disorders.

METHODS

The AOP was constructed in five steps. First, the adverse outcome was formulated clearly and specifically. Second, the link between the molecular initiating event and the adverse outcome was established with a preliminary literature search in the Medline database. Third, a systematic literature search was performed in which we identified 95 relevant articles. Fourth, the main biological processes and relevant key events were identified. Fifth, the links between key events were determined and an AOP network was constructed.

RESULTS

We identified three pathways through which TNF-α may affect fear learning. First, TNF-α receptor activation increases NF-κB levels which increases oxidative stress levels and reduces the activity of glutamate transporters. This alters the synaptic plasticity which is associated with impaired fear acquisition, consolidation, and fear extinction. Second, activation of TNF-α receptors increases the expression and capacity of the serotonin transporter which is linked to impaired fear acquisition, expression, and extinction. Third, TNF-α receptor 1 activation can induce necroptosis, leading to neuroinflammation which is linked to fear learning deficits.

CONCLUSION

To successfully apply the AOP approach in neuroimmunology we recommend defining adverse outcomes more precisely, establishing stronger connections between key events from various biological processes, incorporating feedforward and feedback loops, and identifying more mechanistic knowledge in later key events. These adjustments are needed to map the complex processes within the field of neuroimmunology and to identify gaps of knowledge.

Association between peripheral plasma cytokine levels and suicidal ideation in first-episode, drug-naïve major depressive disorder

BACKGROUND

Inflammatory processes could potentially impact both mood and suicide risk, however, the relationship between cytokines and suicidal ideation remains unclear. This study aimed to investigate the association between plasma levels of cytokines and suicidal ideation in population with major depressive disorders (MDD).

METHODS

A cross-sectional study was performed to assess the peripheral plasma levels of interleukin-1β (IL-1β), IL-2, IL-6, IL-8, IL-10 and tumor necrosis factor-α (TNF-α) in 88 Chinese Han first-episode drug-naïve MDD patients. Suicidal ideation in the past week were identified using the Beck Scale for Suicide Ideation-Chinese Version (BSI-CV). The Hamilton Depression Rating Scale-17 (HAMD-17), the Hamilton Anxiety Rating Scale-14 (HAMA-14) and the Childhood Trauma Questionnaire (CTQ) was used to assess depression, anxiety and childhood trauma. Multivariable logistic regression models were used to estimate the association between cytokines and suicidal ideation. Interaction and stratified analyses were conducted according to age, sex, marital status, education, smoking status, BMI and physical activity.

RESULTS

Among the 88 participants, 42 individuals (47.7%) reported suicidal ideation within the past week. In the fully adjusted model, a statistically significant trend was observed in the association between IL-2 level and suicidal ideation (OR: 1.40, 95% CI: 1.00-1.97). The stratified analysis showed a statistically significant association between IL-6 level and suicidal ideation among younger people (OR: 1.17, 95% CI: 1.01-1.36) and a significant positive association between IL-8 (OR: 1.59, 95% CI: 1.03-2.44) and IL-10 (OR: 2.51, 95% CI: 1.27-4.96) levels and suicide ideation among higher educated populations.

LIMITATIONS

The cross-sectional design, residual confounding effects and small sample size CONCLUSION: Our findings indicate a significant positive association between plasma IL-2 level and suicidal ideation in MDD patients. IL-2 has the potential to be a biomarker of suicidal ideation in patients with depression.

Natural History and Outcomes of Individuals With Functional Bowel Disorder: A 9-year Population-Based Longitudinal Study

INTRODUCTION

Long-term studies characterizing the natural history of functional bowel disorder (FBD) from community-based settings and exploring association with psychological factors are sparse. We aimed to evaluate the evolution of symptoms, health outcomes, and association of FBD with psychological disorders in Chinese population.

METHODS

Individuals identified from random sampling of residents of Hangzhou, China, participated in a baseline survey in January 2010. Follow-up phone survey was conducted in December 2018. FBD was diagnosed based on Rome III criteria.

RESULTS

Among 452 individuals (mean age 44.6 ± 15.3 years, 174 [38%] male) who completed the study, the prevalence of FBD was 36.3% (95% confidence interval [CI] 32.6-40.0%) at enrollment and 36.1% (95% CI 32.3-39.8%) at follow-up survey ( P = 0.94). However, 214 individuals (47%) had interval change in diagnosis. Although no difference in incidence of organic disease or death was observed, a higher proportion of patients with FBD (16/164, 9.8% vs 9/288, 3.1%; P = 0.003) compared with those without FBD received non-cancer-related abdominal and/or pelvic surgery during follow-up. FBD was associated with anxiety and/or depression at initial (adjusted odds ratio [AOR] = 1.7, 95% CI 1.7-2.7, P = 0.02) and follow-up (AOR = 8.0, 95% CI 3.2-20.0, P < 0.001) surveys. Diagnosis of FBD at baseline was associated with new-onset anxiety and/or depression at follow-up (AOR = 3.2, 95% CI 1.2-8.3, P = 0.01).

DISCUSSION

Although the prevalence of FBD remained stable, transformation of symptoms was common over time. Patients with FBD may have increased risk of receiving non-cancer-related abdominal and/or pelvic surgery. FBD symptoms at baseline increased the risk of new-onset anxiety and/or depression by 3.2-fold over the next 9 years.

Resocialization mitigates depressive behaviors induced by social isolation stress in mice: Attenuation of hippocampal neuroinflammation and nitrite level

BACKGROUND AND AIM

Social isolation stress (SIS) is a stressor known to trigger depressive behaviors. Psychiatric disorders are associated with neurobiological changes, such as neuroinflammation and an increase in nitric oxide (NO) signaling. Despite the well-established detrimental effects of SIS and the involvement of neuroinflammation and NO in depression, potential management strategies, especially resocialization, remain insufficiently explored. Our aim was to elucidate the effects of resocialization on depressive behaviors in socially isolated mice, with a focus on the possible involvement of neuroinflammation and nitrite in the hippocampus (HIP).

METHODS

We utilized 24 Naval Medical Research Institute male mice, maintained under both social and isolation conditions (SC and IC). After the isolation period, the mice were divided into two groups of eight, including the SIS group and a resocialized group. The SC group was kept without exposure to isolation stress. We conducted the open-field test, forced swimming test, and splash test to evaluate depressive behaviors. Additionally, nitrite levels, as well as the gene expression of interleukin (IL)-1β, tumor necrosis factor (TNF), and toll-like receptor 4 (TLR4) in the HIP, were measured.

RESULTS

The study found that resocialization significantly reduces depressive behaviors in SIS mice. The results suggest that the antidepressive effects of resocialization may be partially due to the modulation of the neuroinflammatory response and nitrite levels in the HIP. This is supported by the observed decrease in hippocampal gene expression of IL-1β, TLR4, and TNF, along with a reduction in nitrite levels following resocialization.

CONCLUSION

These insights could pave the way for new management strategies for depression, emphasizing the potential benefits of social interactions.

Systems biology dissection of PTSD and MDD across brain regions, cell types, and blood

The molecular pathology of stress-related disorders remains elusive. Our brain multiregion, multiomic study of posttraumatic stress disorder (PTSD) and major depressive disorder (MDD) included the central nucleus of the amygdala, hippocampal dentate gyrus, and medial prefrontal cortex (mPFC). Genes and exons within the mPFC carried most disease signals replicated across two independent cohorts. Pathways pointed to immune function, neuronal and synaptic regulation, and stress hormones. Multiomic factor and gene network analyses provided the underlying genomic structure. Single nucleus RNA sequencing in dorsolateral PFC revealed dysregulated (stress-related) signals in neuronal and non-neuronal cell types. Analyses of brain-blood intersections in >50,000 UK Biobank participants were conducted along with fine-mapping of the results of PTSD and MDD genome-wide association studies to distinguish risk from disease processes. Our data suggest shared and distinct molecular pathology in both disorders and propose potential therapeutic targets and biomarkers.

Niuhuang Qingxin Wan ameliorates depressive-like behaviors and improves hippocampal neurogenesis through modulating TrkB/ERK/CREB signaling pathway in chronic restraint stress or corticosterone challenge mice

Introduction: Chronic stress-associated hormonal imbalance impairs hippocampal neurogenesis, contributing to depressive and anxiety behaviors. Targeting neurogenesis is thus a promising antidepressant therapeutic strategy. Niuhuang Qingxin Wan (NHQXW) is an herbal formula for mental disorders in Traditional Chinese Medicine (TCM) practice, but its anti-depressant efficacies and mechanisms remain unverified. Methods: In the present study, we tested the hypothesis that NHQXW could ameliorate depressive-like behaviors and improve hippocampal neurogenesis by modulating the TrkB/ERK/CREB signaling pathway by utilizing two depression mouse models including a chronic restraint stress (CRS) mouse model and a chronic corticosterone (CORT) stress (CCS) induced mouse model. The depression-like mouse models were orally treated with NHQXW whereas fluoxetine was used as the positive control group. We evaluated the effects of NHQXW on depressive- and anxiety-like behaviors and determined the effects of NHQXW on inducing hippocampal neurogenesis. Results: NHQXW treatment significantly ameliorated depressive-like behaviors in those chronic stress mouse models. NHQXW significantly improved hippocampal neurogenesis in the CRS mice and CCS mice. The potential neurogenic mechanism of NHQXW was identified by regulating the expression levels of BDNF, TrkB, p-ERK (T202/T204), p-MEK1/2 (S217/221), and p-CREB (S133) in the hippocampus area of the CCS mice. NHQXW revealed its antidepressant and neurogenic effects that were similar to fluoxetine. Moreover, NHQXW treatment revealed long-term effects on preventing withdrawal-associated rebound symptoms in the CCS mice. Furthermore, in a bioactivity-guided quality control study, liquiritin was identified as one of the bioactive compounds of NHQXW with the bioactivities of neurogenesis-promoting effects. Discussion: Taken together, NHQXW could be a promising TCM formula to attenuate depressive- and anxiety-like behaviors against chronic stress and depression. The underlying anti-depressant mechanisms could be correlated with its neurogenic activities by stimulating the TrkB/ERK/CREB signaling pathway.

Investigating the Potential Mechanisms and Therapeutic Targets of Inflammatory Cytokines in Post-stroke Depression

Post-stroke depression (PSD) affects approximately one-third of stroke survivors, severely impacting general recovery and quality of life. Despite extensive studies, the exact mechanisms underlying PSD remain elusive. However, emerging evidence implicates proinflammatory cytokines, including interleukin-1β, interleukin-6, tumor necrosis factor-alpha, and interleukin-18, play critical roles in PSD development. These cytokines contribute to PSD through various mechanisms, including hypothalamic-pituitary-adrenal (HPA) axis dysfunction, neurotransmitter alterations, neurotrophic factor changes, gut microbiota imbalances, and genetic predispositions. This review is aimed at exploring the role of cytokines in stroke and PSD while identifying their potential as specific therapeutic targets for managing PSD. A more profound understanding of the mechanisms regulating inflammatory cytokine expression and anti-inflammatory cytokines like interleukin-10 in PSD may facilitate the development of innovative interventions to improve outcomes for stroke survivors experiencing depression.

Peripheral Blood Inflammatory Cytokine Factors Expressions are Associated with Response to Acupuncture Therapy in Postpartum Depression Patients

Background

Increasing evidences demonstrate that immune dysregulation can result in depression, and it is reported that persistent inflammatory response is related to the unresponsiveness of antidepressant treatment.

Purpose

This study aimed to explore the reason why some responded but some not responded to acupuncture in treating postpartum depression (PPD), and whether it related to the levels of inflammatory cytokines.

Patients and Methods

Women diagnosed with PPD were recruited in to accept 8-week acupuncture. All subjects were assessed the 17-item Hamilton Depression Rating Scale (HDRS17) at baseline, week 1, week 2, week 4 and week 8 during the treatment. A panel of 9 cytokines was measured at baseline and 8 weeks.

Results

Of the 121 participants, 96 completed the 8-week assessment and 46 completed the blood sample collection. HDRS17 scores of 96 subjects showed significant statistical reduction since the first week (P = 0.002) and reached to 5.31 (P < 0.000) at the end of therapy. And we divided the 46 subjects into responders and non-responders according to the response rate of HDRS17 scores. Responders and non-responders did not differ significantly between-group in changes in the 9 cytokines. In responders, IL-6, IL-10 and IFN-γ levels were statistically lower (P = 0.006; P = 0.033; P = 0.024), while TGF-β1 was statistically higher after 8 weeks treatment (P < 0.000). In non-responders, the levels of IL-5, TNF-α and TGF-β1 were statistically higher (P = 0.018; P < 0.000; P < 0.000), while IFN-γ was statistically lower (P = 0.005).

Conclusion

Acupuncture could alleviate depressive symptoms of patients with PPD and might through adjusting peripheral inflammatory response by up-regulating anti-inflammatory cytokines and down-regulating pro-inflammatory cytokines.

Fenofibrate Decreases Ethanol-Induced Neuroinflammation and Oxidative Stress and Reduces Alcohol Relapse in Rats by a PPAR-α-Dependent Mechanism

High ethanol consumption triggers neuroinflammation, implicated in sustaining chronic alcohol use. This inflammation boosts glutamate, prompting dopamine release in reward centers, driving prolonged drinking and relapse. Fibrate drugs, activating peroxisome proliferator-activated receptor alpha (PPAR-α), counteract neuroinflammation in other contexts, prompting investigation into their impact on ethanol-induced inflammation. Here, we studied, in UChB drinker rats, whether the administration of fenofibrate in the withdrawal stage after chronic ethanol consumption reduces voluntary intake when alcohol is offered again to the animals (relapse-type drinking). Furthermore, we determined if fenofibrate was able to decrease ethanol-induced neuroinflammation and oxidative stress in the brain. Animals treated with fenofibrate decreased alcohol consumption by 80% during post-abstinence relapse. Furthermore, fenofibrate decreased the expression of the proinflammatory cytokines tumor necrosis factor-alpha (TNF-α) and interleukins IL-1β and IL-6, and of an oxidative stress-induced gene (heme oxygenase-1), in the hippocampus, nucleus accumbens, and prefrontal cortex. Animals treated with fenofibrate showed an increase M2-type microglia (with anti-inflammatory proprieties) and a decrease in phagocytic microglia in the hippocampus. A PPAR-α antagonist (GW6471) abrogated the effects of fenofibrate, indicating that they are dependent on PPAR-α activation. These findings highlight the potential of fenofibrate, an FDA-approved dyslipidemia medication, as a supplementary approach to alleviating relapse severity in individuals with alcohol use disorder (AUD) during withdrawal.

Meta-analysis of soluble tumour necrosis factor receptors in severe mental illnesses

Tumour necrosis factor (TNF), as an innate immune defense molecule, functions through binding to TNF receptor 1 (TNFR1) or TNF receptor 2 (TNFR2). Peripheral levels of soluble TNFR1 (sTNFR1) and soluble TNFR2 (sTNFR2) were widely measured in severe mental illnesses (SMIs) including schizophrenia (SCZ), bipolar disorder (BD) and major depressive disorder (MDD) but inconsistencies existed. Hence, the present meta-analysis was conducted to identify the overall association between plasma/serum sTNFR1 and sTNFR2 levels and SMIs. Published studies were searched using Pubmed and Scopus. Data were analysed using Comprehensive Meta-Analysis version 2. Hedges's g effect sizes and 95% confidence intervals were pooled using fixed-effect or random-effects models. Heterogeneity, publication bias and study quality were assessed. Sensitivity analysis and subgroup analysis were performed. Our findings revealed that sTNFR1 level was significantly higher in SMI, particularly in BD. The sTNFR2 level significantly elevated in SMI but with smaller effect size. These findings further support the association between altered immune system and inflammatory abnormalities in SMI, especially in patients with BD. Subgroup analysis showed that younger age of onset, longer illness duration and psychotropic medication raised both sTNFR levels, especially sTNFR1, as these factors may contribute to the activation of inflammation. Future studies were suggested to identify the causality between TNFR pathway and SCZ, BD and MDD respectively using homogenous group of each SMI, and to determine the longitudinal effect of each psychotropic medication on TNFR pathway.

Guanosine treatment prevents lipopolysaccharide-induced depressive-like behavior in mice

Guanosine is a purinergic nucleoside that has been shown to have neuroprotective effects, mainly through its ability to modulate the glutamatergic system. An increase in pro-inflammatory cytokine levels triggers the activation of the enzyme indoleamine 2,3-dioxygenase 1 (IDO-1), leading to glutamatergic excitotoxicity, which has important roles in the pathophysiology of depression. The aim of this study was to investigate the possible antidepressant-like effects and underlying mechanisms of action of guanosine against lipopolysaccharide (LPS)-induced depression in a mouse model. Mice were orally pre-treated with saline (0.9% NaCl), guanosine (8 or 16 mg/kg), or fluoxetine (30 mg/kg) for 7 days before LPS (0.5 mg/kg, intraperitoneal) injection. One day after LPS injection, mice were subjected to the forced swim test (FST), tail suspension test (TST), and open field test (OFT). After the behavioral tests, mice were euthanized and the levels of tumor necrosis factor-α (TNF-α), IDO-1, glutathione, and malondialdehyde in the hippocampus were measured. Pretreatment with guanosine was able to prevent LPS- induced depressive-like behaviors in the TST and FST. In the OFT, no locomotor changes were observed with any treatment. Both guanosine (8 and 16 mg/kg/day) and fluoxetine treatment prevented the LPS-induced increase in TNF-α and IDO expression and lipid peroxidation as well as decrease of reduced glutathione levels in the hippocampus. Taken together, our findings suggest that guanosine may have neuroprotective effects against LPS-induced depressive-like behavior through preventing oxidative stress and the expression of IDO-1 and TNF-α in the hippocampus.

Blocking coprophagy increases the levels of inflammation and depression in healthy mice as well as mice receiving fecal microbiota transplantation from disease model mice donors

Rodents have been extensively used as animal models in microbiome studies. However, all rodents have a habitual nature called coprophagy, a phenomenon that they self-reinoculate feces into their gastrointestinal tract. Recent studies have shown that blocking coprophagy can alter rodents' diversity of gut microbiota, metabolism, neurochemistry, and cognitive behavior. However, whether rodents' coprophagy behavior affects the levels of inflammation and depression is unclear. In order to address this problem, we first blocked coprophagy in healthy mice. It displayed an increase in the levels of depression, verified by depressive-like behaviors and mood-related indicators, and inflammation, verified by the increased levels of the pro-inflammatory cytokine, in coprophagy-blocked mice. Furthermore, we transplanted fecal microbiota from chronic restraint stress (CRS) depression model mice and lipopolysaccharide (LPS) inflammation model mice to healthy recipient mice, respectively. It showed that the disease-like phenotypes in the coprophagy-blocked group were worse than those in the coprophagy-unblocked group, including severer depressive symptoms and higher levels of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α and IFN-γ) in serum, prefrontal cortex (PFC), and hippocampus (HIP). These findings showed that blocking coprophagy in mice not only increased the levels of inflammation and depression in healthy mice but also aggravated inflammation and depression induced by fecal microbiota from disease donors. The discovery may provide a vital reference for future research involving FMT in rodents.

Pristane induced lupus mice as a model for neuropsychiatric lupus (NPSLE)

BACKGROUND

The pristane-induced lupus (PIL) model is a useful tool for studying environmental-related systemic lupus erythematosus (SLE). However, neuropsychiatric manifestations in this model have not been investigated in detail. Because neuropsychiatric lupus (NPSLE) is an important complication of SLE, we investigated the neuropsychiatric symptoms in the PIL mouse model to evaluate its suitability for NPSLE studies.

RESULTS

PIL mice showed olfactory dysfunction accompanied by an anxiety- and depression-like phenotype at month 2 or 4 after pristane injection. The levels of cytokines (IL-1β, IFN-α, IFN-β, IL-10, IFN-γ, IL-6, TNF-α and IL-17A) and chemokines (CCL2 and CXCL10) in the brain and blood-brain barrier (BBB) permeability increased significantly from week 2 or month 1, and persisted throughout the observed course of the disease. Notably, IgG deposition in the choroid plexus and lateral ventricle wall were observed at month 1 and both astrocytes and microglia were activated. Persistent activation of astrocytes was detected throughout the observed course of the disease, while microglial activation diminished dramatically at month 4. Lipofuscin deposition, a sign of neuronal damage, was detected in cortical and hippocampal neurons from month 4 to 8.

CONCLUSION

PIL mice exhibit a series of characteristic behavioral deficits and pathological changes in the brain, and therefore might be suitable for investigating disease pathogenesis and for evaluating potential therapeutic targets for environmental-related NPSLE.

Anxiolytic and antidepressive potentials of rosmarinic acid: A review with a focus on antioxidant and anti-inflammatory effects

Depression and anxiety are the most prevalent neuropsychiatric disorders that have emerged as global health concerns. Anxiolytic and antidepressant drugs, such as benzodiazepines, selective serotonin reuptake inhibitors, monoamine oxidase inhibitors, and tricyclics, are the first line used in treating anxiety and depression. Although these drugs lack efficacy and have a delayed response time and numerous side effects, their widespread abuse and market continue to grow. Over time, traditional practices using natural and phytochemicals as alternative therapies to chemical drugs have emerged to treat many pathological conditions, including anxiety and depression. Recent preclinical studies have demonstrated that the phenolic compound, rosmarinic acid, is effective against several neuropsychiatric disorders, including anxiety and depression. In addition, rosmarinic acid showed various pharmacological effects, such as cardioprotective, hepatoprotective, lung protective, antioxidant, anti-inflammatory, and neuroprotective effects. However, the potentialities of the use of rosmarinic acid in the treatment of nervous system-related disorders, such as anxiety and depression, are less or not yet reviewed. Therefore, the purpose of this review was to present several preclinical and clinical studies, when available, from different databases investigating the effects of rosmarinic acid on anxiety and depression. These studies showed that rosmarinic acid produces advantageous effects on anxiety and depression through its powerful antioxidant and anti-inflammatory properties. This review will examine and discuss the possibility that the anxiolytic and anti-depressive effects of rosmarinic acid could be associated with its potent antioxidant and anti-inflammatory activities.

Exploring the role of biologics in depression

Depression is a chronic and prevalent neuropsychiatric disorder; clinical symptoms include excessive sad mood, anhedonia, increased anxiety, disturbed sleep, and cognitive deficits. The exact etiopathogenesis of depression is not well understood. Studies have suggested that tumor necrosis factor-alpha (TNF-α) and interleukins (ILs) perform vital roles in the pathogenesis and treatment of depression. Increasing evidence suggests the upregulation of TNF-α and ILs expression in patients with depression. Therefore, biologics like TNF inhibitors (etanercept, infliximab, adalimumab) and IL inhibitors (ustekinumab) have become key compounds in the treatment of depression. Interestingly, treatment with an antidepressant has been found to decrease the TNF-α level and improve depression-like behaviors in several preclinical and clinical studies. In the current article, we have reviewed the recent findings linking TNF-α and the pathogenesis of depression proving TNF-α inhibitors as potential new therapeutic agents. Animal models and clinical studies further support that TNF-α inhibitors are effective in ameliorating depression-like behaviors. Moreover, studies showed that peripheral injection of TNF-α exhibits depressive symptoms. These symptoms have been improved by treatment with TNF-α inhibitors. Hence suggesting TNF-α inhibitors as potential new antidepressants for the management of depressive disorder.

Central and cardiac stress resiliences consistently linked to integrated immuno-neuroendocrine responses across stress models in male mice

Stress resilience, and behavioural and cardiovascular impacts of chronic stress, are theorised to involve integrated neuro-endocrine/inflammatory/transmitter/trophin signalling. We tested for this integration, and whether behaviour/emotionality, together with myocardial ischaemic tolerance, are consistently linked to these pathways across diverse conditions in male C57Bl/6 mice. This included: Restraint Stress (RS), 1 hr restraint/day for 14 days; Chronic Unpredictable Mild Stress (CUMS), 7 stressors randomised over 21 days; Social Stress (SS), 35 days social isolation with brief social encounters in final 13 days; and Control conditions (CTRL; un-stressed mice). Behaviour was assessed via open field (OFT) and sucrose preference (SPT) tests, and neurobiology from frontal cortex (FC) and hippocampal transcripts. Endocrine factors, and function and ischaemic tolerance in isolated hearts, were also measured. Model characteristics ranged from no behavioural or myocardial changes with homotypic RS, to increased emotionality and cardiac ischaemic injury (with apparently distinct endocrine/neurobiological profiles) in CUMS and SS models. Highly integrated expression of HPA axis, neuro-inflammatory, BDNF, monoamine, GABA, cannabinoid and opioid signalling genes was confirmed across conditions, and consistent/potentially causal correlations identified for: i) Locomotor activity (noradrenaline, ghrelin; FC Crhr1, Tnfrsf1b, Il33, Nfkb1, Maoa, Gabra1; hippocampal Il33); ii) Thigmotaxis (adrenaline, leptin); iii) Anxiety-like behaviour (adrenaline, leptin; FC Tnfrsf1a; hippocampal Il33); iv) Depressive-like behaviour (ghrelin; FC/hippocampal s100a8); and v) Cardiac stress-resistance (noradrenaline, leptin; FC Il33, Tnfrsf1b, Htr1a, Gabra1, Gabrg2; hippocampal Il33, Tnfrsf1a, Maoa, Drd2). Data support highly integrated pathway responses to stress, and consistent adipokine, sympatho-adrenergic, inflammatory and monoamine involvement in mood and myocardial disturbances across diverse conditions.

Multi-strain Probiotic Formulation Reverses Maternal Separation and Chronic Unpredictable Mild Stress-Generated Anxiety- and Depression-like Phenotypes by Modulating Gut Microbiome-Brain Activity in Rats

Depression is a debilitating mental disorder that affects >322 million people worldwide. Despite the availability of several antidepressant agents, many patients remain treatment refractory. A growing literature study has indicated the role of gut microbiota in neuropsychiatric disorders. Herein, we examined the psychobiotic-like activity of multi-strain probiotic formulation in maternal separation (MS) and chronic unpredictable mild stress (CUMS) models of anxiety- and depression-like phenotypes in Sprague-Dawley rats. Early- and late-life stress was employed in both male and female rats by exposing them to MS and CUMS. The multi-strain probiotic formulation (Cognisol) containing Bacillus coagulans Unique IS-2, Lactobacillus plantarum UBLP-40, Lactobacillus rhamnosus UBLR-58, Bifidobacterium lactis UBBLa-70, Bifidobacterium breve UBBr-01, and Bifidobacterium infantis UBBI-01 at a total strength of 10 billion cfu along with l-glutamine was administered for 6 weeks via drinking water. Neurobehavioral assessment was done using the forced swim test (FST), sucrose preference test (SPT), elevated plus maze (EPM), and open field test (OFT). Animals were sacrificed after behavioral assessment, and blood, brain, and intestine samples were collected to analyze the levels of cytokines, metabolites, and neurotransmitters and histology. Animals exposed to stress showed increased passivity, consumed less sucrose solution, and minimally explored the open arms in the FST, SPT, and EPM, respectively. Administration of multi-strain probiotics along with l-glutamine for 6 weeks ameliorated the behavioral abnormalities. The locomotor activity of animals in the OFT and their body weight remained unchanged across the groups. Cognisol treatment reversed the decreased BDNF and serotonin levels and increased CRP, TNF-α, and dopamine levels in the hippocampus and/or frontal cortex. Administration of Cognisol also restored the plasma levels of l-tryptophan, l-kynurenine, kynurenic-acid, and 3-hydroxyanthranilic acid; the Firmicutes-to-Bacteroides ratio; the levels of acetate, propionate, and butyrate in fecal samples; the villi/crypt ratio; and the goblet cell count, which manifested in the restoration of intestinal functions. We suggest that the multi-strain probiotic and glutamine formulation (Cognisol) ameliorated the MS + UCMS-generated anxiety- and depression-like phenotypes by reshaping the gut microbiome-brain activity in both sexes.

The IL-1β, IL-6, and TNF cytokine triad is associated with post-acute sequelae of COVID-19

Post-acute sequelae of COVID-19 (PASC) is emerging as global problem with unknown molecular drivers. Using a digital epidemiology approach, we recruited 8,077 individuals to the cohort study for digital health research in Germany (DigiHero) to respond to a basic questionnaire followed by a PASC-focused survey and blood sampling. We report the first 318 participants, the majority thereof after mild infections. Of those, 67.8% report PASC, predominantly consisting of fatigue, dyspnea, and concentration deficit, which persists in 60% over the mean 8-month follow-up period and resolves independently of post-infection vaccination. PASC is not associated with autoantibodies, but with elevated IL-1β, IL-6, and TNF plasma levels, which we confirm in a validation cohort with 333 additional participants and a longer time from infection of 10 months. Blood profiling and single-cell data from early infection suggest the induction of these cytokines in COVID-19 lung pro-inflammatory macrophages creating a self-sustaining feedback loop.

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We report a post-COVID-19 digital epidemiology study with biomarker analysis (n = 651)

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PASC persists in 60% of participants up to 24 months after mild COVID-19

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PASC is associated with high IL-1β, IL-6, and TNF levels but not autoantibodies

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Overactivated monocytes/macrophages are likely the source of cytokine production

Dietary inflammatory index and depression risk in patients with chronic diseases and comorbidity

BACKGROUND

The coexistence of depression and chronic diseases can lead to greater disability and increased mortality. The objective of this study was to examine the association between Dietary Inflammatory Index (DII) and depression in patients with chronic diseases and comorbidity.

METHODS

Multivariable logistic regression analysis was used to investigate the relationship between DII and depression. Dose response relationship was analyzed using a generalized additive model with the smoothing plot.

RESULTS

A total of 7870 chronic diseases patients were enrolled. In multivariate model, the highest quintile of DII was associated with increased risk of depression in patients with diabetes (OR:1.73, 95CI%: 1.17, 2.57), hypertension (OR:1.93, 95CI%: 1.47, 2.52), coronary heart disease (OR:2.65, 95CI%: 1.18, 5.94). The dose response relationship curve suggested the DII tended to be linearly associated with depression in patients with chronic diseases and comorbidity, and the ORs for risk of depression increased with the increase of DII. Furthermore, in patients had at least one chronic comorbidity, the subgroup analysis results showed that those who age<60 years or male participants had higher risk of depression, with ORs (95% CIs) of 2.60 (1.81, 3.74) and 2.51 (1.65, 3.81), respectively.

CONCLUSION

The current study demonstrates that a higher DII is associated with an increased risk of depression in participants with chronic diseases and comorbidity, especially among those less than 60 years and men. Considering diet as a modifiable factor, limiting pro-inflammatory diet or encouraging anti-inflammatory diet may be an effective way to prevent depression and reduce depressive symptoms.

G721-0282 Exerts Anxiolytic-Like Effects on Chronic Unpredictable Mild Stress in Mice Through Inhibition of Chitinase-3-Like 1-Mediated Neuroinflammation

Chronic stress is thought to be a major contributor to the onset of mental disorders such as anxiety disorders. Several studies have demonstrated a correlation between anxiety state and neuroinflammation, but the detailed mechanism is unclear. Chitinase-3-like 1 (CHI3L1) is expressed in several chronic inflammatorily damaged tissues and is well known to play a major role in mediating inflammatory responses. In the present study, we investigated the anxiolytic-like effect of N-Allyl-2-[(6-butyl-1,3-dimethyl-2,4-dioxo-1,2,3,4-tetrahydropyrido[2,3-d]pyrimidin-5-yl)sulfanyl]acetamide (G721-0282), an inhibitor of CHI3L1, on mice treated with chronic unpredictable mild stress (CUMS), as well as the mechanism of its action. We examined the anxiolytic-like effect of G721-0282 by conducting several behavioral tests with oral administration of G721-0282 to CUMS-treated BALB/c male mice. We found that administration of G721-0282 relieves CUMS-induced anxiety. Anxiolytic-like effects of G721-0282 have been shown to be associated with decreased expressions of CUMS-induced inflammatory proteins and cytokines in the hippocampus. The CUMS-elevated levels of CHI3L1 and IGFBP3 were inhibited by treatment with G721-0282 in vivo and in vitro. However, CHI3L1 deficiency abolished the anti-inflammatory effects of G721-0282 in microglial BV-2 cells. These results suggest that G721-0282 could lower CUMS-induced anxiety like behaviors by regulating IGFBP3-mediated neuroinflammation via inhibition of CHI3L1.

Animal Model of Neonatal Immune Challenge by Lipopolysaccharide: A Study of Sex Influence in Behavioral and Immune/Neurotrophic Alterations in Juvenile Mice

INTRODUCTION

The prenatal/perinatal exposure to infections may trigger neurodevelopmental alterations that lead to neuropsychiatric disorders such as autism spectrum disorder (ASD). Previous evidence points to long-term behavioral consequences, such as autistic-like behaviors in rodents induced by lipopolysaccharide (LPS) pre- and postnatal (PN) exposure during critical neurodevelopmental periods. Additionally, sex influences the prevalence and symptoms of ASD. Despite this, the mechanisms underlying this influence are poorly understood. We aim to study sex influences in behavioral and neurotrophic/inflammatory alterations triggered by LPS neonatal exposure in juvenile mice at an approximate age of ASD diagnosis in humans.

METHODS

Swiss male and female mice on PN days 5 and 7 received a single daily injection of 500 μg/kg LPS from Escherichia coli or sterile saline (control group). We conducted behavioral determinations of locomotor activity, repetitive behavior, anxiety-like behavior, social interaction, and working memory in animals on PN25 (equivalent to 3-5 years old of the human). To determine BDNF levels in the prefrontal cortex and hippocampus, we used animals on PN8 (equivalent to a human term infant) and PN25. In addition, we evaluated iba-1 (microglia marker), TNFα, and parvalbumin expression on PN25.

RESULTS

Male juvenile mice presented repetitive behavior, anxiety, and working memory deficits. Females showed social impairment and working memory deficits. In the neurochemical analysis, we detected lower BDNF levels in brain areas of female mice that were more evident in juvenile mice. Only LPS-challenged females presented a marked hippocampal expression of the microglial activation marker, iba-1, and increased TNFα levels, accompanied by a lower parvalbumin expression.

DISCUSSION/CONCLUSION

Male and female mice presented distinct behavioral alterations. However, LPS-challenged juvenile females showed the most prominent neurobiological alterations related to autism, such as increased microglial activation and parvalbumin impairment. Since these sex-sensitive alterations seem to be age-dependent, a better understanding of changes induced by the exposure to specific risk factors throughout life represents essential targets for developing strategies for autism prevention and precision therapy.

How Inflammation Affects the Brain in Depression: A Review of Functional and Structural MRI Studies

This narrative review discusses how peripheral and central inflammation processes affect brain function and structure in depression, and reports on recent peripheral inflammatory marker-based functional and structural magnetic resonance imaging (MRI) studies from the perspective of neural-circuit dysfunction in depression. Chronic stress stimulates the activity of microglial cells, which increases the production of pro-inflammatory cytokines in the brain. In addition, microglial activation promotes a shift from the synthesis of serotonin to the synthesis of neurotoxic metabolites of the kynurenine pathway, which induces glutamate-mediated excitotoxicity in neurons. Furthermore, the region specificity of microglial activation is hypothesized to contribute to the vulnerability of specific brain regions in the depression-related neural circuits to inflammation-mediated brain injury. MRI studies are increasingly investigating how the blood levels of inflammatory markers such as C-reactive protein, interleukin (IL)-1β, IL-6, and tumor necrosis factor-α are associated with functional and structural neuroimaging markers in depression. Functional MRI studies have found that peripheral inflammatory markers are associated with aberrant activation patterns and altered functional connectivity in neural circuits involved in emotion regulation, reward processing, and cognitive control in depression. Structural MRI studies have suggested that peripheral inflammatory markers are related to reduced cortical gray matter and subcortical volumes, cortical thinning, and decreased integrity of white matter tracts within depression-related neural circuits. These neuroimaging findings may improve our understanding of the relationships between neuroinflammatory processes at the molecular level and macroscale in vivo neuralcircuit dysfunction in depression.

CKD-506: A novel HDAC6-selective inhibitor that exerts therapeutic effects in a rodent model of multiple sclerosis

Despite advances in therapeutic strategies for multiple sclerosis (MS), the therapy options remain limited with various adverse effects. Here, the therapeutic potential of CKD-506, a novel HDAC6-selective inhibitor, against MS was evaluated in mice with myelin oligodendrocyte glycoprotein35-55 (MOG35-55)-induced experimental autoimmune encephalitis (EAE) under various treatment regimens. CKD-506 exerted prophylactic and therapeutic effects by regulating peripheral immune responses and maintaining blood-brain barrier (BBB) integrity. In MOG35-55-re-stimulated splenocytes, CKD-506 decreased proliferation and downregulated the expression of IFN-γ and IL-17A. CKD-506 downregulated the levels of pro-inflammatory cytokines in the blood of EAE mice. Additionally, CKD-506 decreased the leakage of intravenously administered Evans blue into the spinal cord; CD4+ T cells and CD4-CD11b+CD45+ macrophage/microglia in the spinal cord was also decreased. Moreover, CKD-506 exhibited therapeutic efficacy against MS, even when drug administration was discontinued from day 15 post-EAE induction. Disease exacerbation was not observed when fingolimod was changed to CKD-506 from day 15 post-EAE induction. CKD-506 alleviated depression-like behavior at the pre-symptomatic stage of EAE. In conclusion, CKD-506 exerts therapeutic effects by regulating T cell- and macrophage-mediated peripheral immune responses and strengthening BBB integrity. Our results suggest that CKD-506 is a potential therapeutic agent for MS.

TNF signaling via TNF receptors does not mediate the effects of short-term exercise on cognition, anxiety and depressive-like behaviors in middle-aged mice

BACKGROUND

We recently reported that tumor necrosis factor (TNF) signaling via the TNFR1 and TNFR2 receptors mediates the effects of long-term exercise on locomotion, cognition and anxiety, but not depressive-like behavior. We now investigated whether the TNF signaling via its receptors also mediates the effects of short-term exercise on cognition, anxiety and depressive-like behaviors.

METHODS

Thirteen-month-old C57BL/6 (WT), TNF^-/-, TNFR1^-/-, and TNFR2^-/- mice were provided with 4 weeks of voluntary wheel running followed by behavioral testing using an established behavioral battery. Each genotype had a respective non-exercise control.

RESULTS

There was no interaction between genotype and exercise in any of the tests but the main effect of genotype, and not exercise, were found to be significant in the open field (OF), forced-swim test (FST) and Barnes maze (BM). In the OF, the control and exercise TNFR2^-/- mice spent significantly less time in the inner zone than mice in the control and exercise WT and TNF^-/- cohorts. In the FST, control and exercise WT mice showed significantly higher immobility time than their control and exercise TNF^-/-, TNFR1^-/- and TNFR2^-/- cohorts. In the BM, the latency to escape over 4 days of training was significantly higher in all KO groups compared to WT, irrespective of exercise. Also, the latency to escape to the original location during the probe trial was higher for control and exercise WT compared to corresponding TNFR1^-/- mice. In contrast, the latency to escape to the new location was lower for control and exercise WT compared to control and exercise TNFR1^-/- and TNFR2^-/- mice. The latency to escape to the new location in exercise groups was longer compared to control within all genotypes.

CONCLUSION

While TNF signaling via the TNF receptors mediates cognition, anxiety and depressive-like behaviors independently, it does not mediate the effects of short-term exercise on these behaviors in middle-aged mice.

Cognitive Impairment in SLE: Mechanisms and Therapeutic Approaches

A wide range of patients with systemic lupus erythematosus (SLE) suffer from cognitive dysfunction (CD) which severely impacts their quality of life. However, CD remains underdiagnosed and poorly understood. Here, we discuss current findings in patients and in animal models. Strong evidence suggests that CD pathogenesis involves known mechanisms of tissue injury in SLE. These mechanisms recruit brain resident cells, in particular microglia, into the pathological process. While systemic immune activation is critical to central nervous system injury, the current focus of therapy is the microglial cell and not the systemic immune perturbation. Further studies are critical to examine additional potential therapeutic targets and more specific treatments based on the cause and progress of the disease.

Melatonin-Pretreated Mesenchymal Stem Cells Improved Cognition in a Diabetic Murine Model

Diabetes mellitus (DM) is a multisystem endocrine disorder affecting the brain. Mesenchymal stem cells (MSCs) pretreated with Melatonin have been shown to increase the potency of MSCs. This work aimed to compare Melatonin, stem cells, and stem cells pretreated with Melatonin on the cognitive functions and markers of synaptic plasticity in an animal model of type I diabetes mellitus (TIDM). Thirty-six rats represented the animal model; six rats for isolation of MSCs and 30 rats were divided into five groups: control, TIDM, TIDM + Melatonin, TIDM + Stem cells, and TIDM + Stem ex vivo Melatonin. Functional assessment was performed with Y-maze, forced swimming test and novel object recognition. Histological and biochemical evaluation of hippocampal Neuroligin 1, Sortilin, Brain-Derived Neurotrophic Factor (BDNF), inducible nitric oxide synthase (iNOS), toll-like receptor 2 (TLR2), Tumor necrosis factor-alpha (TNF-α), and Growth Associated Protein 43 (GAP43). The TIDM group showed a significant decrease of hippocampal Neuroligin, Sortilin, and BDNF and a significant increase in iNOS, TNF-α, TLR2, and GAP43. Melatonin or stem cells groups showed improvement compared to the diabetic group but not compared to the control group. TIDM + Stem ex vivo Melatonin group showed a significant improvement, and some values were restored to normal. Ex vivo melatonin-treated stem cells had improved spatial working and object recognition memory and depression, with positive effects on glucose homeostasis, inflammatory markers levels and synaptic plasticity markers expression.

Ingestion of probiotic (Lactobacillus helveticus and Bifidobacterium longum) alters intestinal microbial structure and behavioral expression following social defeat stress

Social stress exacerbates anxious and depressive behaviors in humans. Similarly, anxiety- and depressive-like behaviors are triggered by social stress in a variety of non-human animals. Here, we tested whether oral administration of the putative anxiolytic probiotic strains Lactobacillus helveticus R0052 and Bifidobacterium longum R0175 reduces the striking increase in anxiety-like behavior and changes in gut microbiota observed following social defeat stress in Syrian hamsters. We administered the probiotic at two different doses for 21 days, and 16S rRNA gene amplicon sequencing revealed a shift in microbial structure following probiotic administration at both doses, independently of stress. Probiotic administration at either dose increased anti-inflammatory cytokines IL-4, IL-5, and IL-10 compared to placebo. Surprisingly, probiotic administration at the low dose, equivalent to the one used in humans, significantly increased social avoidance and decreased social interaction. This behavioral change was associated with a reduction in microbial richness in this group. Together, these results demonstrate that probiotic administration alters gut microbial composition and may promote an anti-inflammatory profile but that these changes may not promote reductions in behavioral responses to social stress.

Flare-up of cytokines in rheumatoid arthritis and their role in triggering depression: Shared common function and their possible applications in treatment (Review)

Chronic illnesses are associated with an increased risk of depression and anxiety. Rheumatoid arthritis (RA) is a chronic autoimmune disease that typically causes damage to the joints. RA extensively impacts patients, both physically and psychologically. Depression is a common comorbid disorder with RA, which leads to worsened health outcomes. There are several cytokines that are active in the joints of patients with RA. Inflammatory cytokines serve important roles in the key processes in the joints, which usually cause inflammation, articular damage and other comorbidities associated with RA. The key role of inflammatory cytokines could be attributed to their interactions within signaling pathways. In RA, IL-1, and the cytokines of TNF-α, IL-6 and IL-18 are primarily involved. Furthermore, depression is hypothesized to be strongly associated with systemic inflammation, particularly with dysregulation of the cytokine network. The present review summarizes the current state of knowledge on these two diseases from the perspective of inflammation and cytokines, and emphasizes the possible bridge between them by exploring the involvement of systemic cytokines in both conditions.

Immune activity at birth and later psychopathology in childhood

Disruption of neurodevelopmental trajectories can alter brain circuitry and increase the risk of psychopathology later in life. While preclinical studies have demonstrated that the immune system and cytokines influence neurodevelopment, whether immune activity and in particular which cytokines at birth are associated with psychopathology remains poorly explored in children. We used data and biological samples from 869 mother-child pairs participating in the French mother-child cohort EDEN. As proxies for immune activity at birth, we measured the levels of 27 cytokines in umbilical cord blood sera (CBS). We then explored the association between CBS cytokine levels and five psychopathological dimensions assessed in 5-year-old children using the Strengths and Difficulties Questionnaire (SDQ). Five cytokines were positively associated with psychopathology: C-X-C motif chemokine Ligand (CXCL)10, interleukin (IL)-10 and IL-12p40 with emotional symptoms, C–C motif chemokine Ligand (CCL)11 with conduct problems, and CCL11, and IL-17A with peer relationships problems. In contrast, seven cytokines were negatively associated with psychopathology: IL-7, IL-15 and Tumor Necrosis Factor (TNF)-β with emotional symptoms, CCL4 and IL-6 with conduct problems, CCL26 and IL-15 with peer relationships problems, and CCL26, IL-7, IL-15, and TNF-α with abnormal prosocial behavior. Without implying causation, these associations support the notion that cytokines influence neurodevelopment in humans and the risk of psychopathology later in life.

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Twelve cytokines at birth are associated with psychopathology in 5-year-old children.

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IL-7, IL-10, IL-12p40, IL-15, TNF-β and CXCL10 are associated with emotional symptoms.

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IL-6, CCL4 and CCL11 are associated with conduct problems.

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IL-15, IL-17A, CCL11 and CCL26 are associated with peer relationship problems.

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IL-7, IL-15, TNF-α and CCL26 are associated with prosocial behavior.

Does the Punishment Fit the Crime (and Immune System)? A Potential Role for the Immune System in Regulating Punishment Sensitivity

Although the criminal justice system is designed around the idea that individuals are invariant in their responses to punishment, research indicates that individuals exhibit a tremendous amount of variability in their punishment sensitivity. This raises the question of why; what are the individual- and situation-level variables that impact a person’s sensitivity to punishment? In the current research, we synthesize theory and research on inflammation, learning, and evolutionary biology to examine the relationship between inflammatory activity and sensitivity to punishment. These theories combine to predict that inflammatory activity – which is metabolically costly and reflects a context in which the net payoff associated with future oriented behaviors is diminished – will decrease sensitivity to punishment, but not rewards. Consistent with this hypothesis, Study 1 found that in U.S. states with a higher infectious disease burden (a proxy for average levels of inflammatory activity) exhibit harsher sentencing in their criminal justice systems. Studies 2 and 3 experimentally manipulated variables known to impact bodily inflammatory activity and measured subsequent punishment and reward sensitivity using a probabilistic selection task. Results revealed that (a) increasing inflammation (i.e., completing the study in a dirty vs. clean room) diminished punishment sensitivity (Study 2), whereby (b) administering a non-steroidal anti-inflammatory drug, suppressing inflammatory activity, enhanced it. No such changes were found for reward sensitivity. Together, these results provide evidence of a link between the activities of the immune system and punishment sensitivity, which may have implications for criminal justice outcomes.

Serum FAM19A5 levels: A novel biomarker for neuroinflammation and neurodegeneration in major depressive disorder

Chronic low-grade inflammation contributes to the pathophysiology of major depressive disorder (MDD). This study aimed to examine the association between serum levels of FAM19A5, a novel chemokine-like peptide that reflects reactive astrogliosis and inflammatory activation in the brain, and the neurodegenerative changes of MDD by investigating the correlation between serum FAM19A5 levels and cortical thickness changes in patients with MDD. We included 52 drug-naïve patients with MDD and 60 healthy controls (HCs). Serum FAM19A5 levels were determined in peripheral venous blood samples using a sandwich enzyme-linked immunosorbent assay. All participants underwent T1-weighted structural magnetic resonance imaging. Serum FAM19A5 levels were greater in patients with MDD than in HCs. In the MDD group, there were significant inverse correlations between serum FAM19A5 levels and cortical thickness in the prefrontal regions (i.e., the left inferior and right medial superior frontal gyri), left posterior cingulate gyrus, right cuneus, and both precunei, which showed significantly reduced thickness in patients with MDD compared to HCs. However, no correlation between serum FAM19A5 level and cortical thickness was observed in the HC group. The results of our study indicate that serum FAM19A5 levels may reflect reactive astrogliosis and related neuroinflammation in MDD. Our findings also suggest that serum FAM19A5 may be a potential biomarker for the neurodegenerative changes of MDD.

Hypothalamus-pituitary-adrenal axis imbalance and inflammation contribute to sex differences in separation- and restraint-induced depression

Whether social contact contributes to the underlying mechanisms of depression and the observed sex differences is unclear. In this study, we subjected young male and female mice to separation- and restraint-induced stress for 4 weeks and assessed behaviors, neurotransmitter levels, hormones, and inflammatory cytokines. Results showed that, compared with controls, male mice exposed to stress displayed significant decreases in body weight and sucrose preference after 1 week. In the fourth week, they exhibited a higher degree of anxiety (open field test) and depressive-like behavior (forced swim test). Moreover, the males showed significant decreases in monoamine neurotransmitters, including norepinephrine and dopamine in striatum, and an increase in pro-inflammatory cytokines, such as tumor necrosis factor α and interleukin 1β in serum. In contrast, females showed persistent loss of weight during stress and displayed significant decreases in sucrose preference after stress. Importantly, the females but not males showed activation of the hypothalamus-pituitary-adrenal (HPA) axis, with significantly higher levels adrenocorticotropic hormone. Additionally, mRNA level of c-fos and AVP showed there was significant interaction between stress and sex. Finally, we conclude that an imbalance of the HPA axis and inflammation might be important contributors to sex differences in separation/restraint-induced depressive behavior and that changes might be mediated by c-fos and AVP.

Enhanced conditioning of adverse memories in the mouse modified swim test is associated with neuroinflammatory changes - Effects that are susceptible to antidepressants

Deficient learning and memory are well-established pathophysiologic features of depression, however, mechanisms of the enhanced learning of aversive experiences associated with this disorder are poorly understood. Currently, neurobiological mechanisms of enhanced retention of aversive memories during depression, and, in particular, their relation to neuroinflammation are unclear. As the association between major depressive disorder and inflammation has been recognized for some time, we aimed to address whether neuroinflammatory changes are involved in enhanced learning of adversity in a depressive state. To study this question, we used a recently described mouse model of enhanced contextual conditioning of aversive memories, the modified forced swim model (modFST). In this model, the classic two-day forced swim is followed by an additional delayed session on Day 5, where increased floating behaviour and upregulated glycogen synthase kinase-3 (GSK-3) are context-dependent. Here, increased time spent floating on Day 5, a parameter of enhanced learning of the adverse context, was accompanied by hypercorticosteronemia, increased gene expression of GSK-3α, GSK-3β, c-Fos, cyclooxygenase-1 (COX-1) and pro-inflammatory cytokines interleukin-1 beta (IL-1β), tumor necrosis factor (TNF), and elevated concentrations of protein carbonyl, a marker of oxidative stress, in the prefrontal cortex and hippocampus. There were significant correlations between cytokine levels and GSK-3β gene expression. Two-week administration of compounds with antidepressant properties, imipramine (7 mg/kg/day) or thiamine (vitamin B1; 200 mg/kg/day) ameliorated most of the modFST-induced changes. Thus, enhanced learning of adverse memories is associated with pro-inflammatory changes that should be considered for optimizing pharmacotherapy of depression associated with enhanced learning of aversive memories.

The cytokine network in the pathogenesis of major depressive disorder. Close to translation?

Major depressive disorder (MDD) is a common condition that afflicts the general population across a broad spectrum of ages and social backgrounds. MDD has been identified by the World Health Organization as a leading cause of disability worldwide. Approximately 30% of patients are poor responsive to standard of care (SOC) treatment and novel therapeutic approaches are warranted. Since chronic inflammation, as it is often observed in certain cancers, type 2 diabetes, psoriasis and chronic arthritis, are accompanied by depression, it has been suggested that immunoinflammatory processes may be involved in the pathogenesis of MDD. Cytokines are a group of glycoproteins secreted from lymphoid and non-lymphoid cells that orchestrate immune responses. It has been suggested that a dysregulated production of cytokines may be implicated in the pathogenesis and maintenance of MDD. On the basis of their functions, cytokines can be subdivided in pro-inflammatory and anti-inflammatory cytokines. Since abnormal blood and cerebrospinal fluid of both pro and anti-inflammatory cytokines are altered in MDD, it has been suggested that abnormal cytokine homeostasis may be implicated in the pathogenesis of MDD and possibly to induction of therapeutic resistance. We review current data that indicate that cytokines may represent a useful tool to identify MDD patients that may benefit from tailored immunotherapeutic approaches and may represent a potential tailored therapeutic target.

Systemic Inhibition of Soluble Tumor Necrosis Factor with XPro1595 Exacerbates a Post-Spinal Cord Injury Depressive Phenotype in Female Rats

Spinal cord injury (SCI) is associated with a three-fold risk of major depressive disorder compared with the general population. Current antidepressant therapy is often not as effective in this patient population, suggesting the need for a more efficacious therapeutic target. The goal of this study was to elucidate the role of inflammatory cytokine tumor necrosis factor (TNF) in the dorsal raphe nucleus (DRN, the principle source of serotonin to the brain) in the development and possible treatment of depression after SCI. A depressive phenotype following moderate T9 contusion was identified in adult female rats using a battery of behavioral tests (forced swim test, sucrose preference test, novel object recognition test, open field locomotion, and social exploration). Data revealed two clusters of injured rats (58%) that exhibit increased immobility in the forced swim test, indicating depressive phenotype or a melancholic-depressive phenotype with concomitant decrease in sucrose preference. ElevatedTNF levels in the DRN of these two clusters correlated with increased immobility in the forced swim test. We then tested the efficacy of soluble TNF inhibition with XPro1595 treatment to prevent the depressive phenotype after SCI. Subcutaneous (s.c.) delivery of XPro1595 caused an exacerbation of depressive phenotype, with all treated clusters exhibiting increased forced swim immobility compared with saline-treated non-depressed rats. Intracerebroventricular (i.c.v.) administration of the drug did not prevent or enhance the development of depression after injury. These results suggest a complex role for TNF-based neuroinflammation in SCI-induced depression that needs to be further explored, perhaps in conjunction with a broader targeting of additional post-SCI inflammatory cytokines.

Depression's Unholy Trinity: Dysregulated Stress, Immunity, and the Microbiome

Depression remains one of the most prevalent psychiatric disorders, with many patients not responding adequately to available treatments. Chronic or early-life stress is one of the key risk factors for depression. In addition, a growing body of data implicates chronic inflammation as a major player in depression pathogenesis. More recently, the gut microbiota has emerged as an important regulator of brain and behavior and also has been linked to depression. However, how this holy trinity of risk factors interact to maintain physiological homeostasis in the brain and body is not fully understood. In this review, we integrate the available data from animal and human studies on these three factors in the etiology and progression of depression. We also focus on the processes by which this microbiota-immune-stress matrix may influence centrally mediated events and on possible therapeutic interventions to correct imbalances in this triune.

Depression increases the risk of inflammatory bowel disease, which may be mitigated by the use of antidepressants in the treatment of depression

OBJECTIVE

Depression is associated with IBD, but the effect of antidepressants on IBD has been sparsely studied. We assessed the impact of depression and antidepressant therapies on the development of IBD.

DESIGN

The Health Improvement Network (THIN) was used to identify a cohort of patients with new-onset depression from 1986 to 2012. THIN patients who did not meet the defining criteria for depression were part of the referent group. The outcome was incident Crohn's disease (CD) or ulcerative colitis (UC). Cox proportional hazards modelling was performed to evaluate the rate of Crohn's disease or UC development among patients with an exposure of depression after controlling for age, sex, socioeconomic status, comorbid conditions, smoking, anxiety and antidepressant use including atypical antidepressants, mirtazapine, monoamine oxidase inhibitors (MAOI), serotonin norepinephrine reuptake inhibitors (SNRI), selective serotonin reuptake inhibitors (SSRI), serotonin modulators; and tricyclic antidepressants (TCA).

RESULTS

We identified 403 665 (7.05%) patients with incident depression. Individuals with depression had a significantly greater risk of developing CD (adjusted HR=2.11, 95% CI 1.65 to 2.70) and UC (adjusted HR=2.23, 95% CI 1.92 to 2.60) after controlling for demographic and clinical covariates. SSRI and TCA were protective against CD, whereas mirtazapine, SNRI, SSRI, serotonin modulators and TCA were protective for UC.

CONCLUSION

Patients with a history of depression were more likely to be diagnosed with IBD. In contrast, antidepressant treatments were selectively protective for Crohn's disease and UC. These results may impact counselling and management of depression and IBD.

The enduring effects of early-life stress on the microbiota-gut-brain axis are buffered by dietary supplementation with milk fat globule membrane and a prebiotic blend

Nutritional interventions targeting the microbiota-gut-brain axis are proposed to modulate stress-induced dysfunction of physiological processes and brain development. Maternal separation (MS) in rats induces long-term alterations to behaviour, pain responses, gut microbiome and brain neurochemistry. In this study, the effects of dietary interventions (milk fat globule membrane [MFGM] and a polydextrose/galacto-oligosaccharide prebiotic blend) were evaluated. Diets were provided from postnatal day 21 to both non-separated and MS offspring. Spatial memory, visceral sensitivity and stress reactivity were assessed in adulthood. Gene transcripts associated with cognition and stress and the caecal microbiota composition were analysed. MS-induced visceral hypersensitivity was ameliorated by MFGM and to greater extent with the combination of MFGM and prebiotic blend. Furthermore, spatial learning and memory were improved by prebiotics and MFGM alone and with the combination. The prebiotic blend and the combination of the prebiotics and MFGM appeared to facilitate return to baseline with regard to HPA axis response to the restraint stress, which can be beneficial in times where coping mechanisms to stressful events are required. Interestingly, the combination of MFGM and prebiotic reduced the long-term impact of MS on a marker of myelination in the prefrontal cortex. MS affected the microbiota at family level only, while MFGM, the prebiotic blend and the combination influenced abundance at family and genus level as well as influencing beta-diversity levels. In conclusion, intervention with MFGM and prebiotic blend significantly impacted the composition of the microbiota as well as ameliorating some of the long-term effects of early-life stress.

Minocycline prevents the development of depression-like behavior and hippocampal inflammation in a rat model of Alzheimer's disease

RATIONALE

Considerable clinical and experimental studies have shown that depression-related disorders are the most common neuropsychiatric symptoms in Alzheimer's disease (AD), affecting as many as 20-40% of patients. An increasing amount of evidence shows that monoamine-based antidepressant treatments are not completely effective for depression treatment in patients with dementia. Minocycline, a second-generation tetracycline antibiotic, has been gaining research and clinical attention for the treatment of different neuropsychiatric disorders, and more recently depression symptom in humans.

METHODS

In the present study, we investigated the effects of Aβ1-42 administration alone or in combination with minocycline treatment on depression-like behaviors and anti/pro-inflammatory cytokines such as interleukin(IL)-10, IL-β, and tumor necrosis factor (TNF)-α in the hippocampus of rats.

RESULTS

Our results showed that Aβ1-42 administration increased depression-related behaviors in sucrose preference test, tail suspension test, novelty-suppressed feeding test, and forced swim test. We also found significant increases in IL-1β and TNF-α levels in the hippocampus of Aβ1-42-treated rats. Interestingly, minocycline treatment significantly reversed depression-related behaviors and the levels of hippocampal cytokines in Aβ1-42-treated rats.

CONCLUSION

These findings support the idea that there is a significant relationship among AD, depression-related symptoms, and pro-inflammatory cytokines in the brain, and suggest that antidepressant-like impacts of minocycline could be due to its anti-inflammatory properties. This drug could be of potential interest for the treatment of depression in patients with Alzheimer's disease.

The Association between Depression and Type 1 Diabetes Mellitus: Inflammatory Cytokines as Ferrymen in between?

The depression incidence is much higher in patients with diabetes mellitus (DM), and the majority of these cases remain under-diagnosed. Type 1 diabetes mellitus (T1D) is now widely thought to be an organ-specific autoimmune disease. As a chronic autoimmune condition, T1D is characterized by T cell-mediated selective loss of insulin-producing β-cells. The age of onset of T1D is earlier than T2D, and T1D patients have an increased vulnerability to depression due to its diagnosis and treatment burden occurring in a period when the individuals are young. The literature has suggested that inflammatory cytokines play a wide role in both diseases. In this review, the mechanisms behind the initiation and propagation of the autoimmune response in T1D and depression are analyzed, and the contribution of cytokines to both conditions is discussed. This review outlines the immunological mechanism of T1D and depression, with a particular emphasis on the role of tumor necrosis factor-α (TNF-α), IL-1β, and interferon-γ (IFN-γ) cytokines and their signaling pathways. The purpose of this review is to highlight the possible pathways of the cytokines shared by these two diseases via deciphering their cytokine cascades. They may provide a basic groundwork for future study of the possible mechanism that links these two diseases and to develop new compounds that target the same pathway but can conquer two diseases.

Exploring the Potential Antidepressant Mechanisms of TNFα Antagonists

Human and animal studies suggest an intriguing relationship between the immune system and the development of depression. Some peripherally produced cytokines, such as TNF-α, can cross the blood brain barrier and result in activation of brain microglia which produces additional TNF-α and fosters a cascade of events including decreases in markers of synaptic plasticity and increases in neurodegenerative events. This is exemplified by preclinical studies, which show that peripheral administration of pro-inflammatory cytokines can elicit depression-like behavior. Importantly, this depression-like behavior can be ameliorated by anti-cytokine therapies. Work in our laboratory suggests that TNF-α is particularly important for the development of a depressive phenotype and that TNF-α antagonists might have promise as novel antidepressant drugs. Future research should examine rates of inflammation at baseline in depressed patients and whether anti-inflammatory agents could be included as part of the treatment regimen for depressive disorders.

The effects of rotenone on TH, BDNF and BDNF-related proteins in the brain and periphery: Relevance to early Parkinson's disease

Loss of dopaminergic neurons in the substantia nigra (SN) is one of the pathological hallmarks in Parkinson's disease (PD). This neuron loss is accompanied by reduced protein and activity levels of tyrosine hydroxylase (TH), the rate-limiting enzyme of catecholamine synthesis. Reduced nigral brain-derived neurotrophic factor (BDNF) has been postulated to contribute to the loss of nigral dopaminergic neurons in PD by causing a lack of trophic support. Prior to this nigral cell loss many patients develop non-motor symptoms such as hyposmia, constipation and orthostatic hypotension. We investigated how TH, BDNF and BDNF related receptors are altered in the SN, olfactory bulb, adrenal glands and colon (which are known to be affected in PD) using rotenone-treated rats. Rotenone was administered to Sprague-Dawley rats at a dose of 2.75 mg/kg, 5 days/week for 4 weeks, via intraperitoneal injections. Rats underwent behavioural testing, and tissues were collected for western blot and ELISA analysis. This rotenone treatment induced reduced rears and distance travelled in the rearing and open field test, respectively but caused no impairments in forced movement (rotarod test). The SN had changes consistent with a pro-apoptotic state, such as increased proBDNF but no change in TH; whereas, the colon had significantly reduced TH and increased sortilin. Thus, our results indicate further investigation is warranted for this rotenone-dosing paradigm's capacity for reproducing the early stage of PD, as we observed impairments in voluntary movement and pathology in the colon without overt motor symptoms or nigral dopaminergic loss.

Atorvastatin prevents lipopolysaccharide-induced depressive-like behaviour in mice

Clinical and pre-clinical evidences indicate an association between inflammation and depression since increased levels of pro-inflammatory cytokines are associated with depression-related symptoms. Atorvastatin is a cholesterol-lowering statin that possesses pleiotropic effects including neuroprotective and antidepressant actions. However, the putative neuroprotective effect of atorvastatin treatment in the acute inflammation mice model of depressive-like behaviour has not been investigated. In the present study, we aimed to investigate the effect of atorvastatin treatment on lipopolysaccharide (LPS) induced depressive-like behaviour in mice. Mice were treated with atorvastatin (1 or 10 mg/kg, v.o.) or fluoxetine (30 mg/kg, positive control, v.o.) for 7 days before LPS (0.5 mg/kg, i.p.) injection. Twenty four hours after LPS infusion, mice were submitted to the forced swim test, tail suspension test or open field test. After the behavioural tests, mice were sacrificed and the levels of tumour necrosis factor-α (TNF-α), brain-derived neurotrophic factor (BDNF), glutathione and malondialdehyde were measured. Atorvastatin (1 or 10 mg/kg/day) or fluoxetine treatment prevented LPS-induced increase in the immobility time in the forced swim and tail suspension tests with no alterations in the locomotor activity evaluated in the open field test. Atorvastatin (1 or 10 mg/kg/day) or fluoxetine treatment also prevented LPS-induced increase in TNF-α and reduction of BDNF levels in the hippocampus and prefrontal cortex. Treatment with atorvastatin (1 or 10 mg/kg/day) or fluoxetine prevented LPS-induced increase in lipid peroxidation and the reduction of glutathione levels in the hippocampus and prefrontal cortex. The present study suggests that atorvastatin treatment exerted neuroprotective effects against LPS-induced depressive-like behaviour which may be related to reduction of TNF-α release, oxidative stress and modulation of BDNF expression.