Stress-induced neuroinflammation: role of the Toll-like receptor-4 pathway

FGF2 gene's antisense protein, NUDT6, plays a depressogenic role by promoting inflammation and suppressing neurogenesis without altering FGF2 signalling

Fibroblast growth factor-2 (FGF2) is involved in the regulation of affective behaviour and shows antidepressant effects through the Akt and extracellular signal regulated kinase (ERK) 1/2 pathways. Nudix hydrolase 6 (NUDT6) protein is encoded from FGF2 gene's antisense strand and its role in the regulation of affective behaviour is unknown. Here, we overexpressed NUDT6 in the hippocampus and investigated its behavioural effects and the underlying molecular mechanisms affecting the behaviour. We showed that increasing hippocampal NUDT6 results in depression-like behaviour in rats without changing FGF2 levels or activating its downstream effectors, Akt and ERK1/2. Instead, NUDT6 acted by inducing inflammatory signalling, specifically by increasing S100 calcium binding protein A9 (S100A9) levels, activating nuclear factor-kappa B-p65 (NF-κB-p65), and elevating microglia numbers along with a reduction in neurogenesis. Our results suggest that NUDT6 could play a role in major depression by inducing a proinflammatory state. This is the first report of an antisense protein acting through a different mechanism of action than regulation of its sense protein. The opposite effects of NUDT6 and FGF2 on depression-like behaviour may serve as a mechanism to fine-tune affective behaviour. Our findings open up new venues for studying the differential regulation and functional interactions of sense and antisense proteins in neural function and behaviour, as well as in neuropsychiatric disorders. KEY POINTS: Hippocampal overexpression of nudix hydrolase 6 (NUDT6), the antisense protein of fibroblast growth factor-2 (FGF2), increases depression-like behaviour in rats. Hippocampal NUDT6 overexpression triggers a neuroinflammatory cascade by increasing S100 calcium binding proteinA9 (S100A9) expression and nuclear NF-κB-p65 translocation in neurons, in addition to microglial recruitment and activation. Hippocampal NUDT6 overexpression suppresses neurogenesis. NUDT6 exerts its actions without altering the levels or downstream signalling pathways of FGF2.

Toll-Like Receptor mRNA Levels in Schizophrenia: Association With Complement Factors and Cingulate Gyrus Cortical Thinning

BACKGROUND AND HYPOTHESES

Previous studies revealed innate immune system activation in people with schizophrenia (SZ), potentially mediated by endogenous pathogen recognition receptors, notably Toll-like receptors (TLR). TLRs are activated by pathogenic molecules like bacterial lipopolysaccharides (TLR1 and TLR4), viral RNA (TLR3), or both (TLR8). Furthermore, the complement system, another key component of innate immunity, has previously been linked to SZ.

STUDY DESIGN

Peripheral mRNA levels of TLR1, TLR3, TLR4, and TLR8 were compared between SZ and healthy controls (HC). We investigated their relationship with immune activation through complement expression and cortical thickness of the cingulate gyrus, a region susceptible to immunological hits. TLR mRNA levels and peripheral complement receptor mRNA were extracted from 86 SZ and 77 HC white blood cells; structural MRI scans were conducted on a subset.

STUDY RESULTS

We found significantly higher TLR4 and TLR8 mRNA levels and lower TLR3 mRNA levels in SZ compared to HC. TLRs and complemental factors were significantly associated in SZ and HC, with the strongest deviations of TLR mRNA levels in the SZ subgroup having elevated complement expression. Cortical thickness of the cingulate gyrus was inversely associated with TLR8 mRNA levels in SZ, and with TLR4 and TLR8 levels in HC.

CONCLUSIONS

The study underscores the role of innate immune activation in schizophrenia, indicating a coordinated immune response of TLRs and the complement system. Our results suggest there could be more bacterial influence (based on TLR 4 levels) as opposed to viral influence (based on TLR3 levels) in schizophrenia. Specific TLRs were associated with brain cortical thickness reductions of limbic brain structures.

Doxycycline-Loaded Calcium Phosphate Nanoparticles with a Pectin Coat Can Ameliorate Lipopolysaccharide-Induced Neuroinflammation Via Enhancing AMPK

Neuroinflammation occurs in response to different injurious triggers to limit their hazardous effects. However, failure to stop this process can end in multiple neurological diseases. Doxycycline (DX) is a tetracycline, with potential antioxidant and anti-inflammatory properties. The current study tested the effects of free DX, DX-loaded calcium phosphate (DX@CaP), and pectin-coated DX@CaP (Pec/DX@CaP) nanoparticles on the lipopolysaccharide (LPS)-induced neuroinflammation in mice and to identify the role of adenosine monophosphate-activated protein kinase (AMPK) in this effect. The present study was conducted on 48 mice, divided into 6 groups, eight mice each. Group 1 (normal control), Group 2 (blank nanoparticles-treated), Group 3 (LPS (untreated)), Groups 4, 5, and 6 received LPS, then Group 4 received free DX, Group 5 received DX-loaded calcium phosphate nanoparticles (DX@CaP), and Group 6 received DX-loaded calcium phosphate nanoparticles with a pectin coat (Pec/DX@CaP). At the end of the experimentation period, behavioral tests were carried out. Then, mice were sacrificed, and brain tissue was extracted and used for histological examination, and assessment of interleukin-6 positive cells in different brain areas, in addition to biochemical measurement of SOD activity, TLR-4, AMPK and Nrf2. LPS can induce prominent neuroinflammation. Treatment with (Pec/DX@CaP) can reverse most behavioral, histopathological, and biochemical changes caused by LPS. The findings of the current study suggest that (Pec/DX@CaP) exerts a significant reverse of LPS-induced neuroinflammation by enhancing SOD activity, AMPK, and Nrf2 expression, in addition to suppression of TLR-4.

Differential regulation of innate immune system in frontal cortex and hippocampus in a "double-hit" neurodevelopmental model in rats

Neurodevelopmental disorders (NDs) are neuropsychiatric conditions affecting central nervous system development, characterized by cognitive and behavioural alterations. Inflammation has been recently linked to NDs. Animal models are essential for understanding their pathophysiology and identifying therapeutic targets. Double-hit models can reproduce neurodevelopmental and neuroinflammatory impairments. Sixty-seven newborn rats were assigned to four groups: Control, Maternal deprivation (MD, 24-h-deprivation), Isolation (Iso, 5 weeks), and Maternal deprivation ​+ ​Isolation (MD ​+ ​Iso, also known as double-hit). Cognitive dysfunction was assessed using behavioural tests. Inflammasome, MAPKs, and TLRs inflammatory elements expression in the frontal cortex (FC) and hippocampus (HP) was analysed through western blot and qRT-PCR. Oxidative/nitrosative (O/N) evaluation and corticosterone levels were measured in plasma samples. Double-hit group was affected in executive and working memory. Most inflammasomes and TLRs inflammatory responses were increased in FC compared to the control group, whilst MAPKs were downregulated. Conversely, hippocampal inflammasome and inflammatory components were reduced after the double-hit exposure, while MAPKs were elevated. Our findings reveal differential regulation of innate immune system components in FC and HP in the double-hit group. Further investigations on MAPKs are necessary to understand their role in regulating HP neuroinflammatory status, potentially linking our MAPKs results to cognitive impairments through their proliferative and anti-inflammatory activity.

Clinical and preclinical evaluation of miR-144-5p as a key target for major depressive disorder

BACKGROUND

Neuronal abnormalities are closely associated with major depressive disorder (MDD). Available evidence suggests a role for microRNAs (miRNAs) in regulating the expression of genes involved in MDD. Hence, miRNAs that can be potential therapeutic targets need to be identified.

METHODS

A mouse model of chronic unpredictable stress (CUS) was used to evaluate the function of miRNAs in MDD. miR-144-5p was screened from the hippocampi of CUS mice based on sequencing results. Adenovirus-associated vectors were used to overexpress or knockdown miR-144-5p in mice. BpV(pic) and LY294002 were used to determine the relationship between miR-144-5p target genes PTEN and TLR4 in neuronal impairment caused by miR-144-5p deficiency. Western blotting, immunofluorescence, ELISA immunosorbent assay, and Golgi staining were used to detect neuronal abnormalities. Serum samples from healthy individuals and patients with MDD were used to detect miR-144-5p levels in the serum and serum exosomes using qRT-PCR.

RESULTS

miR-144-5p expression was significantly decreased within the hippocampal dentate gyrus (DG) of CUS mice. Upregulation of miR-144-5p in the DG ameliorated depression-like behavior in CUS mice and attenuated neuronal abnormalities by directly targeting PTEN and TLR4 expression. Furthermore, miR-144-5p knockdown in normal mice led to depression-like behavior via inducing neuronal abnormalities, including abnormal neurogenesis, neuronal apoptosis, altered synaptic plasticity, and neuroinflammation. miR-144-5p deficiency-mediated neuronal impairment was mediated by PI3K/Akt/FoxO1 signaling. Furthermore, miR-144-5p levels were downregulated in the sera of patients with MDD and associated with depressive symptoms. Consistently, serum exosome-derived miR-144-5p levels were decreased in patients with MDD.

CONCLUSION

miR-144-5p plays a vital role in regulating neuronal abnormalities in depression. Our findings provide translational evidence that miR-144-5p is a new potential therapeutic target for MDD.

Targeting inflammatory pathways for treatment of the major depressive disorder

Current treatments modalities for major depressive disorder (MDD) mainly target the monoaminergic neurotransmission. However, the therapeutic inadequacy and adverse effects confine the use of these conventional antidepressants to a limited subset of MDD patients. The classical antidepressants are increasingly proving unsatisfactory in tackling the treatment-resistant depression (TRD). Hence, the focus of treatment is shifting to alternative pathogenic pathways involved in depression. Preclinical and clinical evidences accumulated across the last decades have unequivocally affirmed the causative role of immuno-inflammatory pathways in the progression of depression. There is an upsurge in the clinical evaluations of the drugs having anti-inflammatory effects as antidepressants. This review highlights the molecular mechanisms connecting the inflammatory pathways to the MDD and current clinical status of inflammation modulating drugs in the treatment of MDD.

Prophylactic vs. Therapeutic Effect of Probiotics on the Inflammation Mediated by the NF-κB Pathway in Inflammatory Bowel Conditions

Probiotic supplements consumed adequately at the proper time can affect health by modulating inflammatory pathways in gastrointestinal epithelial cells and modifying the resultant inflammatory response. The current study applied in vitro models to investigate the effectiveness of probiotics in modulating inflammatory pathways and altering inflammatory gene expression in gastrointestinal epithelial cells, with the ultimate goal of promoting probiotic consumption as a therapeutic and preventive measure for chronic inflammatory bowel conditions. HT-29 cells were treated with Gram-negative bacteria to evaluate the changes in pathways related to inflammation activities before and after treatment with a Lactobacillus spp. cocktail (L. plantarum, L. rhamnosus, L. brevis, and L. ruteri) and a Bifidobacterium spp. cocktail (B. bifidum, B. langum, and B. breve) using the real-time PCR method and ELISA for IL-1β and IL-6 as pro-inflammatory cytokines. The results showed that the expression of NF-κB signaling pathway genes and IL-1β and IL-6 cytokines increased after exposure to Gram-negative components. In contrast, all probiotic combinations significantly decreased the expression of genes and the secretion of cytokines. However, this decrease was significantly smaller in cells that underwent probiotic treatment after inflammation induction. In addition, cocktails containing combined Lactobacillus and Bifidobacterium demonstrated robust anti-inflammatory activity relative to solo cocktails. Our observations confirm that probiotic consumption could positively impact inflammatory conditions and alleviate inflammatory symptoms; they can be particularly effective as a preventive measure. Our study provides preliminary evidence to support the lifetime consumption of probiotics.

Stressor control and regional inflammatory responses in the brain: regulation by the basolateral amygdala

Increasing evidence has connected the development of certain neuropsychiatric disorders, as well as neurodegenerative diseases, to stress-induced dysregulation of the immune system. We have shown that escapable (ES) and inescapable (IS) footshock stress, and memories associated with ES or IS, can differentially alter inflammatory-related gene expression in brain in a region dependent manner. We have also demonstrated that the basolateral amygdala (BLA) regulates stress- and fear memory-induced alterations in sleep, and that differential sleep and immune responses in the brain to ES and IS appear to be integrated during fear conditioning and then reproduced by fear memory recall. In this study, we investigated the role of BLA in influencing regional inflammatory responses within the hippocampus (HPC) and medial prefrontal cortex (mPFC) by optogenetically stimulating or inhibiting BLA in male C57BL/6 mice during footshock stress in our yoked shuttlebox paradigm based on ES and IS. Then, mice were immediately euthanized and RNA extracted from brain regions of interest and loaded into NanoString® Mouse Neuroinflammation Panels for compilation of gene expression profiles. Results showed differential regional effects in gene expression and activated pathways involved in inflammatory-related signaling following ES and IS, and these differences were altered depending on amygdalar excitation or inhibition. These findings demonstrate that the stress-induced immune response, or "parainflammation", is affected by stressor controllability and that BLA influences regional parainflammation to ES or IS in HPC and mPFC. The study illustrates how stress-induced parainflammation can be regulated at the neurocircuit level and suggests that this approach can be useful for uncovering circuit and immune interactions in mediating differential stress outcomes.

Latroeggtoxin-VI protects nerve cells and prevents depression by inhibiting NF-κB signaling pathway activation and excessive inflammation

Depression has a high incidence and seriously endangers human health. Accumulated evidence indicates that targeting neuroinflammation is a potential avenue for neuroprotection and thus depression prevention. Herein, the effects of latroeggtoxin-VI (LETX-VI), a bioactive protein from the eggs of spider Latrodectus tredecimguttatus, on lipopolysaccharide (LPS)-induced inflammation and depression were systematically investigated using RAW264.7 macrophages and depression mouse model. Pretreatment with LETX-VI suppressed LPS-evoked NF-κB signaling pathway activation, inhibited LPS-induced over-production of NO, iNOS, IL-6 and TNF-α; at the same time LETX-VI mitigated the inhibitory effect of LPS on the expression of anti-inflammatory factors such as Arg-1, thereby suppressing oxidative stress and excessive inflammation. Culture of PC12 cells with the conditioned medium of RAW264.7 cells pretreated with LETX-VI demonstrated the neuroprotective effect of LETX-VI due to its anti-inflammation effect. In the LPS-induced depression mouse model, pretreatment with LETX-VI improved the LPS-induced depression-like behaviors, inhibited the activation of microglia and astrocytes, prevented the down-regulation of Nurr1 expression and alleviated the LPS-caused adverse changes in the brain tissues. Taken together, these in vitro and in vivo findings provide powerful insights into the anti-inflammation-based neuroprotective and antidepressant mechanisms of LETX-VI, which is helpful to deeply reveal the biological effects and potential applications of LETX-VI.

Kaixin Jieyu Granule attenuates neuroinflammation-induced depressive-like behavior through TLR4/PI3K/AKT/FOXO1 pathway: a study of network pharmacology and experimental validation

BACKGROUND

Kaixin Jieyu Granule (KJG), an improved formula of Kai-xin-san and Si-ni-san, is a highly effective formula with demonstrated efficacy in preventing depression in previous studies. However, the underlying molecular mechanisms of KJG's antidepressant effects on inflammatory molecules remain unclear. This study aimed to explore the therapeutic effects of KJG on depression using network pharmacology and experimental validation.

METHODS

We employed a multi-faceted approach, combining high-performance liquid chromatography (HPLC), network pharmacology, and molecular docking, to unravel the underlying mechanisms of KJG's anti-depressant effects. To confirm our findings, we conducted at least two independent in vivo experiments on mice, utilizing both the chronic unpredictable mild stress (CUMS)-induced and lipopolysaccharide (LPS)-induced models. Furthermore, the results of in vivo experiments were verified by in vitro assays. Behavioral tests were utilized to evaluate depression-like behaviors, while Nissl staining was used to assess morphological changes in the hippocampus. Pro-inflammatory cytokines and pathway-related protein expressions were determined using a combination of immunofluorescence staining, enzyme-linked immunosorbent assay (ELISA), and Western Blotting (WB).

RESULTS

Our network-based approaches indicated that ginsenoside Rg1 (GRg1) and saikosaponin d (Ssd) are the major constituents of KJG that exert an anti-depressant effect by regulating TLR4, PI3K, AKT1, and FOXO1 targets through the toll-like receptor, PI3K/AKT, and FoxO pathways. In vivo, KJG can attenuate depression-like behaviors, protect hippocampal neuronal cells, and reduce the production of pro-inflammatory mediators (TNF-α, IL-6, and IL-1β) by repressing TLR4 expression, which was regulated by the inhibition of FOXO1 through nuclear exportation. Furthermore, KJG increases the expression levels of PI3K, AKT, p-PI3K, p-AKT, and p-PTEN. Our in vitro assays are consistent with our in vivo studies. On the other hand, the above effects can be reversed by applying TAK242 and LY294002.

CONCLUSION

Our findings suggest that KJG can exert anti-depressant effects by regulating neuroinflammation through the PI3K/AKT/FOXO1 pathway by suppressing TLR4 activation. The study's findings reveal novel mechanisms underlying the anti-depressant effects of KJG, presenting promising avenues for the development of targeted therapeutic approaches for depression.

Chronic stress, neuroinflammation, and depression: an overview of pathophysiological mechanisms and emerging anti-inflammatories

In a subset of patients, chronic exposure to stress is an etiological risk factor for neuroinflammation and depression. Neuroinflammation affects up to 27% of patients with MDD and is associated with a more severe, chronic, and treatment-resistant trajectory. Inflammation is not unique to depression and has transdiagnostic effects suggesting a shared etiological risk factor underlying psychopathologies and metabolic disorders. Research supports an association but not necessarily a causation with depression. Putative mechanisms link chronic stress to dysregulation of the HPA axis and immune cell glucocorticoid resistance resulting in hyperactivation of the peripheral immune system. The chronic extracellular release of DAMPs and immune cell DAMP-PRR signaling creates a feed forward loop that accelerates peripheral and central inflammation. Higher plasma levels of inflammatory cytokines, most consistently interleukin IL-1β, IL-6, and TNF-α, are correlated with greater depressive symptomatology. Cytokines sensitize the HPA axis, disrupt the negative feedback loop, and further propagate inflammatory reactions. Peripheral inflammation exacerbates central inflammation (neuroinflammation) through several mechanisms including disruption of the blood-brain barrier, immune cellular trafficking, and activation of glial cells. Activated glial cells release cytokines, chemokines, and reactive oxygen and nitrogen species into the extra-synaptic space dysregulating neurotransmitter systems, imbalancing the excitatory to inhibitory ratio, and disrupting neural circuitry plasticity and adaptation. In particular, microglial activation and toxicity plays a central role in the pathophysiology of neuroinflammation. Magnetic resonance imaging (MRI) studies most consistently show reduced hippocampal volumes. Neural circuitry dysfunction such as hypoactivation between the ventral striatum and the ventromedial prefrontal cortex underlies the melancholic phenotype of depression. Chronic administration of monoamine-based antidepressants counters the inflammatory response, but with a delayed therapeutic onset. Therapeutics targeting cell mediated immunity, generalized and specific inflammatory signaling pathways, and nitro-oxidative stress have enormous potential to advance the treatment landscape. Future clinical trials will need to include immune system perturbations as biomarker outcome measures to facilitate novel antidepressant development. In this overview, we explore the inflammatory correlates of depression and elucidate pathomechanisms to facilitate the development of novel biomarkers and therapeutics.

Inhibitory effects of fluoxetine on the secretion of inflammatory mediators and JAK/STAT3 and JNK/TLR4 gene expression

BACKGROUND

Selective serotonin reuptake inhibitors (SSRIs) are the most common class of medicines used for the treatment of major depression. Recent studies have reported an association between depression and inflammation and suggested the significant effects of SSRIs on inflammatory processes.

METHODS

The current study aimed to evaluate the effects of fluoxetine, an SSRI, on the level of inflammatory cytokines, including interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α), in the rat serum and RAW264.7 mouse macrophage cell line, using ELISA sandwich assays. Also, the expression of inflammatory genes, including JAK/STAT3 and TLR4/JNK, was examined in macrophages, using real-time quantitative reverse transcription PCR to determine the potential mechanism of fluoxetine in inflammation. The rats received fluoxetine (10, 20, and 40 mg/kg) 30 min before lipopolysaccharide (LPS) treatment for 90 min. The cells received different doses of fluoxetine (5, 10, and 20 µg/mL) before stimulation with LPS for 24 or 48 h.

RESULTS

The serum concentrations of IL-1β, IL-6, and TNF-α were reduced in rats and cells treated with fluoxetine. Following fluoxetine administration, the expression of JAK/STAT3 and TLR4/JNK genes was significantly decreased in the RAW264.7 cells treated with LPS for 24 h. However, after 48 h of treatment with LPS, fluoxetine failed to diminish the elevated expression of JAK and JNK genes, while it significantly decreased the expression of STAT3 and TLR4 genes.

CONCLUSION

The findings revealed that fluoxetine has anti-inflammatory properties, mainly due to the reduction of inflammatory cytokines and inhibition of JAK/STAT3 and TLR4/JNK gene expression in macrophages.

Cognitive dysfunction and neurometabolic alternations in major depressive disorder with gastrointestinal symptoms

BACKGROUND

Brain biochemical abnormalities have been associated with major depressive disorder (MDD) and cognitive impairments. However, the cognitive performance and neurometabolic alterations of MDD patients accompanied by gastrointestinal (GI) symptoms remain to be elucidated. We aimed to reveal the features and correlation between cognitive impairments and brain biochemical abnormalities of depressed patients with GI symptoms.

METHODS

Fifty MDD patients with GI symptoms (GI group), 46 patients without GI symptoms (NGI group) and 50 demographically matched healthy controls (HCs) underwent Measurement and Treatment Research to Improve Cognition in Schizophrenia (MATRICS) Consensus Cognitive Battery (MCCB) assessments. In addition, proton magnetic resonance spectroscopy (¹H-MRS) was used to obtain ratios of N-acetyl aspartate to creatine (NAA/Cr) and choline-containing compounds to creatine (Cho/Cr) in the thalamus, putamen and anterior cingulate cortex (ACC). Finally, association analysis was conducted to investigate the relationships of these measurements.

RESULTS

Compared to HCs, participants in both the GI and NGI groups had significantly reduced performance in the six MCCB cognitive domains (all p < 0.05), except for reasoning and problem solving. Higher Cho/Cr ratios in the right thalamus (p < 0.05) and lower NAA/Cr ratios in the left putamen (p < 0.05) were found in the NGI group than in the GI group. The severity of GI symptoms was negatively correlated with Cho/Cr ratios in the right ACC (r = -0.288, p = 0.037). In addition, the T-scores of visual learning were negatively correlated with NAA/Cr ratios in the right ACC (r = -0.443, p = 0.001) and right thalamus (r = -0.335, p = 0.015).

CONCLUSION

Our findings suggest that MDD patients with GI symptoms may exhibit greater neurometabolic alternations than those without GI symptoms, while both show similar cognitive dysfunction. In addition, neurometabolic alterations in the ACC and thalamus may underlie the neural basis of GI symptoms and cognitive impairment in MDD.

Modeling integrated stress, sleep, fear and neuroimmune responses: Relevance for understanding trauma and stress-related disorders

Sleep and stress have complex interactions that are implicated in both physical diseases and psychiatric disorders. These interactions can be modulated by learning and memory, and involve additional interactions with the neuroimmune system. In this paper, we propose that stressful challenges induce integrated responses across multiple systems that can vary depending on situational variables in which the initial stress was experienced, and with the ability of the individual to cope with stress- and fear-inducing challenges. Differences in coping may involve differences in resilience and vulnerability and/or whether the stressful context allows adaptive learning and responses. We provide data demonstrating both common (corticosterone, SIH and fear behaviors) and distinguishing (sleep and neuroimmune) responses that are associated with an individual's ability to respond and relative resilience and vulnerability. We discuss neurocircuitry regulating integrated stress, sleep, neuroimmune and fear responses, and show that responses can be modulated at the neural level. Finally, we discuss factors that need to be considered in models of integrated stress responses and their relevance for understanding stress-related disorders in humans.

Early Chronic Stress Induced Changes within the Locus Coeruleus in Sporadic Alzheimer's Disease

Chronic exposure to stress throughout the lifespan has been the focus of many studies on Alzheimer's disease (AD) because of the similarities between the biological mechanisms involved in chronic stress and the pathophysiology of AD. In fact, the earliest abnormality associated with the disease is the presence of phosphorylated tau protein in locus coeruleus neurons, a brain structure highly responsive to stress and perceived threat. Here, we introduce allostatic load as a useful concept for understanding many of the complex, interacting neuropathological changes involved in the AD degenerative process. In response to chronic stress, aberrant tau proteins that begin to accumulate within the locus coeruleus decades prior to symptom onset appear to represent a primary pathological event in the AD cascade, triggering a wide range of interacting brain changes involving neuronal excitotoxicity, endocrine alterations, inflammation, oxidative stress, and amyloid plaque exacerbation. While it is acknowledged that stress will not necessarily be the major precipitating factor in all cases, early tau-induced changes within the locus coeruleus-norepinephrine pathway suggests that a therapeutic window might exist for preventative measures aimed at managing stress and restoring balance within the HPA axis.

Influence of dietary Bacillus coagulans and/or Bacillus licheniformis-based probiotics on performance, gut health, gene expression, and litter quality of broiler chickens

Probiotics are non-pathogenic microorganisms that are potentially important non-antibiotic alternatives. This study aimed to compare novel multi-strain and single-strain Bacillus probiotics and their respective influences on broiler chickens' performance, gut health, litter quality, immune response, and NBN and TLR gene expression. A total of 1200 Arbor-Acres 1-day-old broiler chicks were randomly allocated into three treatments (T1 was a control, T2 was supplemented with a combined Bacillus coagulans (2 × 10⁹ cfu/g) and Bacillus licheniformis (8 × 10⁹ cfu/g) probiotic strains (0.2 kg/ton of feed), and T3 was supplemented with Bacillus licheniformis (3.2 × 10⁹ cfu/g) probiotic (0.5 kg/ton of feed) with eight replicas of each. Supplementing the broiler diet with either the single-strain (T3) or the multi-strain (T2) Bacillus-based probiotic raised the overall birds' body weight, body weight gain, feed conversion ratio, and European production efficiency factor compared to the control (T1), with a significant enhancement achieved by the multi-strain Bacillus product (P = 0.005). T2 and T3 exhibited significantly improved cholesterol, Alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, and alkaline phosphatase levels than the control (P ≤ 0.05). The transcript levels of both NBN and TLR genes were upregulated in the liver in the T2 and T3 groups. The T2 group experienced significant reductions in gut bacterial counts, especially for Clostridia, and recorded the lowest litter moisture and nitrogen. In conclusion, supplementing broiler diets with probiotics of multiple Bacillus strains increased production profitability by promoting bird growth, improving feed intake, enhancing gut mucosa and immune organs, and upregulating genes responsible for immunity. All these inhibit the overgrowth of enteric pathogens and sustain litter quality.

Stress- and drug-induced neuroimmune signaling as a therapeutic target for comorbid anxiety and substance use disorders

Stress and substance use disorders remain two of the most highly prevalent psychiatric conditions and are often comorbid. While individually these conditions have a debilitating impact on the patient and a high cost to society, the symptomology and treatment outcomes are further exacerbated when they occur together. As such, there are few effective treatment options for these patients, and recent investigation has sought to determine the neural processes underlying the co-occurrence of these disorders to identify novel treatment targets. One such mechanism that has been linked to stress- and addiction-related conditions is neuroimmune signaling. Increases in inflammatory factors across the brain have been heavily implicated in the etiology of these disorders, and this review seeks to determine the nature of this relationship. According to the "dual-hit" hypothesis, also referred to as neuroimmune priming, prior exposure to either stress or drugs of abuse can sensitize the neuroimmune system to be hyperresponsive when exposed to these insults in the future. This review completes an examination of the literature surrounding stress-induced increases in inflammation across clinical and preclinical studies along with a summarization of the evidence regarding drug-induced alterations in inflammatory factors. These changes in neuroimmune profiles are also discussed within the context of their impact on the neural circuitry responsible for stress responsiveness and addictive behaviors. Further, this review explores the connection between neuroimmune signaling and susceptibility to these conditions and highlights the anti-inflammatory pharmacotherapies that may be used for the treatment of stress and substance use disorders.

Assessment of Performance, Microbial Community, Bacterial Food Quality, and Gene Expression of Whiteleg Shrimp (Litopenaeus vannamei) Reared under Different Density Biofloc Systems

Biofloc shrimp culture, as a way of improving shrimp production, gains worldwide consideration. However, the effects of the biofloc system on shrimp culture at high densities could be a challenge. Here, this study is aimed at identifying a better stocking density of whiteleg shrimp (Litopenaeus vannamei) between two intensive biofloc systems of 100 and 300 org./m². Achieving that was done by comparing growth performance, water quality, feed utilization, microbial loads from water and shrimps, and gene expression of growth, stress, and immune-related genes. Shrimp postlarvae with a mean weight of 35.4 ± 3.7 mg were reared in six indoor cement tanks (36 m³ total capacity each) at two stocking densities (3 replicates each) for a rearing period of 135 days. Better final weight, weight gain, average daily weight gain, specific growth rate, biomass increase percentage, and survival rate were associated with lower density (100/m²), whereas high-density showed significantly higher total biomass. Better feed utilization was found in the lower density treatment. Lower density treatment enhanced water quality parameters, including higher dissolved oxygen and lower nitrogenous wastes. Heterotrophic bacterial count in water samples was recorded as 5.28 ± 0.15 and 5.11 ± 0.28 log CFU/ml from the high- and low-density systems, respectively, with no significant difference. Beneficial bacteria such as Bacillus spp. were identified in water samples from both systems, still, the Vibrio-like count was developed in the higher density system. Regarding shrimp food bacterial quality, the total bacterial count in the shrimp was recorded as 5.09 ± 0.1 log CFU/g in the 300 org./m² treatment compared to 4.75 ± 0.24 log CFU/g in the lower density. Escherichia coli was isolated from the shrimps in a lower density group while Aeromonas hydrophila and Citrobacter freundii were associated with shrimps from a higher density system. Immune-related genes including prophenoloxidase, superoxide dismutase (SOD), and lysozyme (LYZ) expressions were all significantly higher expressed in the shrimp from the lower density treatment. Toll receptor (LvToll), penaiedin4 (PEN4), and stress-related gene (HSP 70) showed a decreased gene expression in the shrimp raised in the lower density. Significant upregulation of growth-related gene (Ras-related protein-RAP) expression was associated with the lower stocking density system. In conclusion, the current study found that applying high stocking density (300 org./m²) contributes negatively to performance, water quality, microbial community, bacterial food quality, and gene expression of immune, stress, and growth-related genes when compared with the lower stocking density system (100 org./m²) under biofloc system.

Controllable and Uncontrollable Stress Differentially Impact Fear Conditioned Alterations in Sleep and Neuroimmune Signaling in Mice

Stress induces neuroinflammation and disrupts sleep, which together can promote a number of stress-related disorders. Fear memories associated with stress can resurface and reproduce symptoms. Our previous studies have demonstrated sleep outcomes can be modified by stressor controllability following stress and fear memory recall. However, it is unknown how stressor controllability alters neuroinflammatory signaling and its association with sleep following fear memory recall. Mice were implanted with telemetry transmitters and experienced escapable or inescapable footshock and then were re-exposed to the shuttlebox context one week later. Gene expression was assessed with Nanostring^® panels using RNA extracted from the basolateral amygdala and hippocampus. Freezing and temperature were examined as behavioral measures of fear. Increased sleep after escapable stress was associated with a down-regulation in neuro-inflammatory and neuro-degenerative related genes, while decreased sleep after inescapable stress was associated with an up-regulation in these genes. Behavioral measures of fear were virtually identical. Sleep and neuroimmune responses appear to be integrated during fear conditioning and reproduced by fear memory recall. The established roles of disrupted sleep and neuroinflammation in stress-related disorders indicate that these differences may serve as informative indices of how fear memory can lead to psychopathology.

The Relationship between Stress, Inflammation, and Depression

A narrative review about the relationship between stress, inflammation, and depression is made as follows: Chronic stress leads to various stress-related diseases such as depression. Although most human diseases are related to stress exposure, the common pathways between stress and pathophysiological processes of different disorders are still debatable. Chronic inflammation is a crucial component of chronic diseases, including depression. Both experimental and clinical studies have demonstrated that an increase in the levels of pro-inflammatory cytokines and stress hormones, such as glucocorticoids, substantially contributes to the behavioral alterations associated with depression. Evidence suggests that inflammation plays a key role in the pathology of stress-related diseases; however, this link has not yet been completely explored. In this study, we aimed to determine the role of inflammation in stress-induced diseases and whether a common pathway for depression exists. Recent studies support pharmacological and non-pharmacological treatment approaches significantly associated with ameliorating depression-related inflammation. In addition, major depression can be associated with an activated immune system, whereas antidepressants can exert immunomodulatory effects. Moreover, non-pharmacological treatments for major depression (i.e., exercise) may be mediated by anti-inflammatory actions. This narrative review highlights the mechanisms underlying inflammation and provides new insights into the prevention and treatment of stress-related diseases, particularly depression.

Puerarin Alleviates Depression-Like Behavior Induced by High-Fat Diet Combined With Chronic Unpredictable Mild Stress via Repairing TLR4-Induced Inflammatory Damages and Phospholipid Metabolism Disorders

Puerarin has been reported as a potential agent for neuro-inflammatory disorders. However, there have been no reports of using puerarin for the treatment of depression based on Toll-like receptor 4 (TLR4)–mediated inflammatory injury. In this study, we evaluated the protective effects of puerarin on depression-like rats induced by a high-fat diet (HFD) combined with chronic unpredictable mild stress (CUMS). The mechanism was screened by lipidomics and molecular docking and confirmed by in vivo tests. Puerarin treatment significantly improved 1% sucrose preference and ameliorated depression-like behavior in the open-field test. The antidepressive effects of puerarin were associated with decreased pro-inflammatory cytokine production, including interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), and increased anti-inflammatory cytokine levels (IL-10) in rat hippocampal tissues and plasma. Hematoxylin–eosin (H&E), immunofluorescence staining, and Western blotting results displayed that puerarin alleviated inflammatory injury by suppressing TLR4 expression and by repairing the intestine mucus barrier via enhancing the expression of claudin-1 and occludin. Non-targeted lipidomics analysis showed that the most significantly different metabolites modified by puerarin were phospholipids. Puerarin treatment–altered biomarkers were identified as PC (15:1/20:1), PE (15:1/16:1), and PI (18:2/20:1) in comparison with the HFD/CUMS group. Molecular docking modeling revealed that puerarin could bind with cytosolic phospholipase A2 (cPLA2) and cyclooxygenase-2 (COX-2), which play central roles in TLR4-mediated phospholipid metabolism. In vivo, puerarin treatment decreased the enzyme activities of cPLA2 and COX-2, resulting in lower production of prostaglandin E₂ (PGE₂) in hippocampal and intestinal tissues. In conclusion, puerarin treatment reverses HFD/CUMS-induced depression-like behavior by inhibiting TLR4-mediated intestine mucus barrier dysfunction and neuro-inflammatory damages via the TLR4/cPLA2/COX-2 pathway.

Inducible Nitric Oxide Synthase Inhibition in the Medial Prefrontal Cortex Attenuates the Anxiogenic-Like Effect of Acute Restraint Stress via CB1 Receptors

Stress exposure can result in several proinflammatory alterations in the brain, including overexpression of the inducible isoform of nitric oxide synthase (iNOS) in the medial prefrontal cortex (mPFC). These changes may be involved in the development of many psychiatric conditions. However, it is unknown if iNOS in mPFC plays a significant role in stress-induced behavioral changes. The endocannabinoid (ECB) system is also influenced by stress. Its activation seems to be a counter regulatory mechanism to prevent or decrease the stress-mediated neuroinflammatory consequences. However, it is unclear if the ECB system and iNOS interact to influence stress consequences. This study aimed to test the hypothesis that the anti-stress effect of iNOS inhibition in mPFC involves the local ECB system, particularly the CB₁ cannabinoid receptors. Male Wistar rats with guide cannula aimed at the mPFC were submitted to acute restraint stress (RS) for 2 h. In the following morning, rats received bilateral microinjections of vehicle, AM251 (CB₁ antagonist; 100 pmol), and/or 1400W (iNOS selective inhibitor; 10^-4, 10^-3, or 10^-2 nmol) into the prelimbic area of mPFC (PL-mPFC) before being tested in the elevated plus-maze (EPM). iNOS inhibition by 1400W prevented the anxiogenic-like effect observed in animals submitted to RS. The drug did not promote behavior changes in naive animals, demonstrating a stress-dependent effect. The 1400W-anti-stress effect was prevented by local pretreatment with AM251. Our data suggest that iNOS inhibition may facilitate the local endocannabinoid signaling, attenuating stress effects.

Gut microbiota, innate immune pathways, and inflammatory control mechanisms in patients with major depressive disorder

Although alterations in the gut microbiota have been linked to the pathophysiology of major depressive disorder (MDD), including through effects on the immune response, our understanding is deficient about the straight connection patterns among microbiota and MDD in patients. Male and female MDD patients were recruited: 46 patients with a current active MDD (a-MDD) and 22 in remission or with only mild symptoms (r-MDD). Forty-five healthy controls (HC) were also recruited. Psychopathological states were assessed, and fecal and blood samples were collected. Results indicated that the inducible nitric oxide synthase expression was higher in MDD patients compared with HC and the oxidative stress levels were greater in the a-MDD group. Furthermore, the lipopolysaccharide (an indirect marker of bacterial translocation) was higher in a-MDD patients compared with the other groups. Fecal samples did not cluster according to the presence or the absence of MDD. There were bacterial genera whose relative abundance was altered in MDD: Bilophila (2-fold) and Alistipes (1.5-fold) were higher, while Anaerostipes (1.5-fold) and Dialister (15-fold) were lower in MDD patients compared with HC. Patients with a-MDD presented higher relative abundance of Alistipes and Anaerostipes (1.5-fold) and a complete depletion of Dialister compared with HC. Patients with r-MDD presented higher abundance of Bilophila (2.5-fold) compared with HC. Thus, the abundance of bacterial genera and some immune pathways, both with potential implications in the pathophysiology of depression, appear to be altered in MDD, with the most noticeable changes occurring in patients with the worse clinical condition, the a-MDD group.

Acute Response of Stress System in Multiple Sclerosis

Background: It has long been suspected that exposure to stress is a major factor that can increase the risk of Multiple Sclerosis (MS) and exacerbate it, as a stress-related disorder. Therefore, we conducted this study to investigate the response of the hypothalamic-pituitary-adrenal (HPA) axis and sympathetic-adrenal-medullar (SAM) system to acute social stress. Methods: A total of 46 MS patients and 23 age-sex-matched healthy controls were recruited in the study. The Trier Social Stress Test (TSST) was used to induce acute psychosocial stress. We measured salivary cortisol (SC) to evaluate the HPA axis. In addition, electrocardiography (ECG) was recorded to evaluate the SAM system based on the linear and non-linear features of Heart Rate Variation (HRV). Then, SC and HRV were measured before and after the stress exposure. We also used the Depression Anxiety Stress Scale (DASS) and Emotional Visual Analog Scale (EVAS) to conduct the psychometric assessment and evaluate the perceived stress level, respectively. Results: The mean age of the MS group was 35.38 ± 15 years, with a mean disease duration of 7.4 ± 60. Besides, the HC group's mean age was 35.8 ± 9 years. There were no significant differences in demographic features and DASS scores between the two groups. In response to TSST, both MS and healthy individuals showed a significant increase in the SC levels and EVAS scores, as well as changes in the HRV indices. Notably, significant differences were also found between the two groups regarding the basic and post-stress SC levels, EVAS score, and HRV indices. Unlike the HC group, the SC level returned to its baseline after recovery in the MS group, and the sympathetic tone was more sensitive. Conclusions: Our results indicated that both MS and healthy individuals respond to acute stress regarding neuroendocrine assessment; however, patients with multiple sclerosis show some impairments in this response.

Effects of Toll-like receptor 4 inhibition on spatial memory and cell proliferation in male and female adult and aged mice

Toll-like receptors (TLRs) participate in the response to infection, stress, and injury by initiating an innate immune response. In addition, these receptors are expressed in many neural cell types and under physiological conditions are implicated in modulating cognitive function and neural plasticity in the adult and aged brain. Knockout of the Toll-like receptor 4 (TLR4) subtype enhances spatial memory and adult hippocampal neurogenesis through increasing proliferation and neuronal differentiation. Currently unknown is whether pharmacological inhibition of TLR4 produces similar enhancements in cognitive function and cell proliferation. The present study evaluated water maze performance, cytokine expression, and cell proliferation in the hippocampus of young and aged male and female C57BL6/J mice following treatment with the TLR4 antagonist, TAK-242. Further, alterations in the response to an acute stressor were evaluated in TAK-242-treated mice. Results showed that TAK-242 selectively enhanced spatial learning and memory in young females. Additionally, TAK-242 treatment reduced thigmotaxis in the water maze and lowered corticosterone levels following acute stress in females. TAK-242 decreased hippocampal interleukin (IL)-1β expression but had no effect on IL-6 or tumor necrosis factor-α (TNFα). Aged mice showed decreased cell proliferation compared to young mice, but TAK-242 administration had minimal effects on estimated Ki67 positive cell numbers. Findings indicate that pharmacological inhibition of TLR4 improves cognitive function in young females likely through attenuating stress reactivity.

Wuzi-Yanzong prescription alleviates spermatogenesis disorder induced by heat stress dependent on Akt, NF-κB signaling pathway

Akt and nuclear factor kappa B (NF-κB) signaling pathways are involved in germ cell apoptosis and inflammation after testicular heat stress (THS). We observed that after THS induced by the exposure of rat testes to 43 °C for 20 min, their weight decreased, the fraction of apoptotic testicular germ cells significantly increased, and the proliferation of germ cells was inhibited. In addition, THS lowered serum testosterone (T) level, whereas the levels of follicle stimulating hormone and luteinizing hormone were not significantly changed. The ultrastructure of the seminiferous tubules became abnormal after THS, the structure of the blood-testis barrier (BTB) became loose, and the Sertoli cells showed a trend of differentiation. The level of phosphorylated Akt was reduced, whereas the amount of phosphorylated NF-κB p65 was augmented by THS. Wuzi-Yanzong (WZYZ), a classic Chinese medicine prescription for the treatment of male reproductive dysfunctions, alleviated the changes induced by THS. In order to determine the mechanism of action of WZYZ, we investigated how this preparation modulated the levels of T, androgen receptor (AR), erythropoietin (EPO), EPO receptor, and Tyro-3, Axl, and Mer (TAM) family of tyrosine kinase receptors. We found that WZYZ activated the Akt pathway, inhibited the Toll-like receptor/MyD88/NF-κB pathway, and repaired the structure of BTB by regulating the levels of T, AR, TAM receptors, and EPO. In conclusion, these results suggest that WZYZ activates the Akt pathway and inhibits the NF-κB pathway by acting on the upstream regulators, thereby improving spermatogenesis deficit induced by THS.

Gut Microbiota and Pathophysiology of Depressive Disorder

BACKGROUND

Accumulating evidence has suggested that the bi-directional communication pathway, the microbiota-gut-brain axis, plays an important role in the pathophysiology of many neuropsychiatric diseases including major depressive disorder (MDD). This review outlines current evidence and promising findings related to the pathophysiology and treatment of MDD.

SUMMARY

There are at least 4 key biological molecules/systems underlying the pathophysiology of MDD: central dopamine, stress responses by the hypothalamic-pituitary-adrenal axis and autonomic nervous system, inflammation, and brain-derived neurotrophic factor. Animal experiments in several depression models have clearly indicated that gut microbiota is closely related to these molecules/systems and administration of probiotics and prebitotics may have beneficial effects on them. Although the results of microbiota profile of MDD patients varied from a study to another, multiple studies reported that bacteria which produce short-chain fatty acids such as butyrate and those protective against metabolic diseases (e.g., Bacteroidetes) were reduced. Clinical trials of probiotics have emerged, and the majority of the studies have reported beneficial effects on depression symptoms and related biological markers. Key Messages: The accumulating evidence suggests that research on the microbiota-gut-brain axis in major depressive disorder (MDD) is promising to elucidate the pathophysiology and to develop novel treatment of MDD, although there is still a long distance yet to reach the goals.

Neuroplastin in human cognition: review of literature and future perspectives

Synaptic glycoprotein neuroplastin is involved in synaptic plasticity and complex molecular events underlying learning and memory. Studies in mice and rats suggest that neuroplastin is essential for cognition, as it is needed for long-term potentiation and associative memory formation. Recently, it was found that some of the effects of neuroplastin are related to regulation of calcium homeostasis through interactions with plasma membrane calcium ATPases. Neuroplastin is increasingly seen as a key factor in complex brain functions, but studies in humans remain scarce. Here we summarize present knowledge about neuroplastin in human tissues and argue its genetic association with cortical thickness, intelligence, schizophrenia, and autism; specific immunolocalization depicting hippocampal trisynaptic pathway; potential role in tissue compensatory response in neurodegeneration; and high, almost housekeeping, level of spatio-temporal gene expression in the human brain. We also propose that neuroplastin acts as a housekeeper of neuroplasticity, and that it may be considered as an important novel cognition-related molecule in humans. Several promising directions for future investigations are suggested, which may complete our understanding of neuroplastin actions in molecular basis of human cognition.

Toll-like receptor 4 methylation grade is linked to depressive symptom severity

This study explores potential associations between the methylation of promoter-associated CpG sites of the toll-like receptor (TLR)-family, plasma levels of pro-inflammatory proteins and depressive symptoms in young female psychiatric patients. Ratings of depressive symptoms and blood samples were obtained from 92 young women seeking psychiatric care. Methylation of 32 promoter-associated CpG sites in TLR1 to TLR10 was analysed using the Illumina Infinium Methylation EPIC BeadChip. Expression levels of 91 inflammatory proteins were determined by proximity extension assay. Statistical correlations between depressive state, TLR1-10 methylation and inflammatory proteins were investigated. Four additional cohorts were studied to evaluate the generalizability of the findings. In the discovery cohort, methylation grade of cg05429895 (TLR4) in blood was inversely correlated with depressive symptoms score in young adults. After correction for multiple testing, plasma levels of macrophage inflammatory protein 1β (MIP-1β/CCL4) were associated with both TLR4 methylation and depressive symptom severity. A similar inverse association between TLR4 methylation in blood and affective symptoms score was also found in a cohort of 148 both males and females (<40 years of age) from the Danish Twin Registry. These findings were not, however, replicated in three other external cohorts; which differed from the first two cohorts by a higher age and mixed ethnicities, thus limiting the generalizability of our findings. However, TLR4 methylation inversely correlated with TLR4 mRNA expression in the Danish Twin Study indicating a functional significance of methylation at this particular CpG. Higher depression scores in young Scandinavian adults was associated with decreased methylation of TLR4 in blood.

How environmental enrichment balances out neuroinflammation in chronic pain and comorbid depression and anxiety disorders

Depression and anxiety commonly occur in chronic pain states and the coexistence of these diseases worsens outcomes for both disorders and may reduce treatment adherence and response. Despite the advances in the knowledge of chronic pain mechanisms, pharmacological treatment is still unsatisfactory. Research based on exposure to environmental enrichment is currently under investigation and seems to offer a promising low-cost strategy with no side effects. In this review, we discuss the role of inflammation as a major biological substrate and aetiological factor of chronic pain and depression/anxiety and report a collection of preclinical evidence of the effects and mechanisms of environmental enrichment. As microglia participates in the development of both conditions, we also discuss microglia as a potential target underlying the beneficial actions of environmental enrichment in chronic pain and comorbid depression/anxiety. We also discuss how alternative interventions under clinical guidelines, such as environmental enrichment, may improve treatment compliance and patient outcomes.

Immunoregulation and antidepressant effect of ketamine

Major depressive disorder (MDD) is a common mental health disorder that brings severe disease burden worldwide. Traditional antidepressants are mainly targeted at monoamine neurotransmitters, with low remission rates and high recurrence rates. Ketamine is a noncompetitive glutamate N-methyl-d-aspartate receptor (NMDAR) antagonist, and its rapid and powerful antidepressant effects have come to light. Its antidepressant mechanism is still unclarified. Research found that ketamine had not only antagonistic effect on NMDAR but also strong immunomodulatory effect, both of which were closely related to the pathophysiology of MDD. Although there are many related studies, they are relatively heterogeneous. Therefore, this review mainly describes the immune mechanisms involved in MDD and how ketamine plays an antidepressant role by regulating peripheral and central immune system, including peripheral inflammatory cytokines, central microglia, and astrocytes. This review summarizes the related research, finds out the deficiencies of current research, and provides ideas for future research and the development of novel antidepressants.

Maternal autoimmunity and inflammation are associated with childhood tics and obsessive-compulsive disorder: Transcriptomic data show common enriched innate immune pathways

Although genetic variation is a major risk factor of neurodevelopmental disorders, environmental factors during pregnancy and early life are also important in disease expression. Animal models demonstrate that maternal inflammation causes fetal neuroinflammation and neurodevelopmental deficits, and brain transcriptomics of neurodevelopmental disorders in humans show upregulated differentially expressed genes are enriched in immune pathways. We prospectively recruited 200 sequentially referred children with tic disorders/obsessive-compulsive disorder (OCD), 100 autoimmune neurological controls, and 100 age-matched healthy controls. A structured interview captured the maternal and family history of autoimmune disease and other pro-inflammatory states. Maternal blood and published Tourette brain transcriptomes were analysed for overlapping enriched pathways. Mothers of children with tics/OCD had a higher rate of autoimmune disease compared with mothers of children with autoimmune neurological conditions (p = 0.054), and mothers of healthy controls (p = 0.0004). Autoimmunity was similarly elevated in first- and second-degree maternal relatives of children with tics/OCD (p < 0.0001 and p = 0.014 respectively). Other pro-inflammatory states were also more common in mothers of children with tics/OCD than controls (p < 0.0001). Upregulated differentially expressed genes in maternal autoimmune disease and Tourette brain transcriptomes were commonly enriched in innate immune processes. Pro-inflammatory states, including autoimmune disease, are more common in the mothers and families of children with tics/OCD. Exploratory transcriptome analysis indicates innate immune signalling may link maternal inflammation and childhood tics/OCD. Targeting inflammation may represent preventative strategies in pregnancy and treatment opportunities for children with neurodevelopmental disorders.

Role of toll-like receptor 4 antagonist Lipopolysaccharide-Rhodobacter sphaeroides on acute stress-induced voluntary ethanol preference and drinking behaviour: In vivo Swiss Albino mouse model

The present study focused on investigating the effect of toll-like receptor 4 (TLR4) antagonist Lipopolysaccharide-Rhodobacter sphaeroides(LPS-RS) on acute, stress-induced voluntary ethanol preference and drinking behaviour, neuronal components activation, and gene expression associated with stress and addictive behaviour. This study involved the exposure of restraint stress and social isolation using Swiss Albino mice. Two-bottle choice ethanol preference analysis was used in the evaluation of voluntary ethanol seeking and drinking behaviour. Several behavioural assessments were carried out to assess fear and anxiety-like behaviour, neuromuscular ability, motor coordination and locomotion. Morphological and immunoreactivity analysis and gene expression analysis were done after the completion of behavioural assessments. TLR4 antagonist LPS-RS treated stressed-mice showed a significant decrease in ethanol drinking compared with stressed mice. Behavioural results showed that stress exposure induced fear and anxiety-like behaviour; however; no significant deficit was found on motor coordination, neuromuscular ability, locomotion and exploratory behaviour among groups. Morphological analysis showed no significant change in the prefrontal cortex and hippocampus among all groups, while immunoreactivity analysis showed higher expression of c-Fos in prefrontal cortex and hippocampus, higher TLR4 expression in the prefrontal cortex and glial fibrillary acidic protein (GFAP) in hippocampus among stressed-animals. Stressed-mice also showed significant increase in TLR4, Nuclear Factor-Kappa B (NF-kB), inducible nitric oxide synthase (iNOS), dopamine receptor D2 (DRD₂), cyclic adenosine monophosphate (cAMP) response element binding protein-1 (CREB-1) and opioid receptor MU-1 (OPRM-1) genes expression compared with control and LPS-RS treated stressed-mice. As a conclusion, the antagonism of TLR4 could provide therapeutic value in the treatment of stress-induced addiction.

Effects of Microbiota Imbalance in Anxiety and Eating Disorders: Probiotics as Novel Therapeutic Approaches

Anxiety and eating disorders produce a physiological imbalance that triggers alterations in the abundance and composition of gut microbiota. Moreover, the gut–brain axis can be altered by several factors such as diet, lifestyle, infections, and antibiotic treatment. Diet alterations generate gut dysbiosis, which affects immune system responses, inflammation mechanisms, the intestinal permeability, as well as the production of short chain fatty acids and neurotransmitters by gut microbiota, which are essential to the correct function of neurological processes. Recent studies indicated that patients with generalized anxiety or eating disorders (anorexia nervosa, bulimia nervosa, and binge-eating disorders) show a specific profile of gut microbiota, and this imbalance can be partially restored after a single or multi-strain probiotic supplementation. Following the PRISMA methodology, the current review addresses the main microbial signatures observed in patients with generalized anxiety and/or eating disorders as well as the importance of probiotics as a preventive or a therapeutic tool in these pathologies.

Ibuprofen Protection Against Restrained Chronic Stress-induced Depression in Male Rats

Introduction:

Stress predisposes organisms to depression and cognitive impairments, and seems to interact with metabolic homeostasis. The inflammatory response and the upregulation of proinflammatory cytokines are some of the consequences related to chronic stress. In this study, we investigated the preventive effect of chronic administration of ibuprofen, as an inhibitor of cyclooxygenases, on the cognitive and behavioral alterations and the weight gain reduction induced by simultaneous chronic restraint stress in rats.

Materials and Methods:

Male Wistar rats were subjected to chronic restraint stress and injected daily with the variable doses of ibuprofen or vehicle, for 21 consecutive days. Then, all animals were tested with the forced swim test and passive avoidance conditioning. Also, the weight of the animals was recorded before and after the interventions. Ultimately, plasma interleukin 6 (IL-6) levels were measured.

Results:

Chronic stress increased depressive-like behaviors, impaired learning, and disrupted the normal weight gain. However, the animals that received the highest dose of ibuprofen showed less depressive-like behaviors, a better avoidance memory, and a higher weight gain. However, the level of plasma IL-6 did not differ significantly between the study groups.

Conclusion:

The administration of ibuprofen prevents the cognitive and behavioral consequences of chronic stress. During the recovery, the plasma levels of IL-6 were not elevated by stress, and the IL-6 levels did not predict the behavioral performance of the stressed animals. The exact mechanisms of the protective effects of ibuprofen against chronic stress need to be further investigated.

Impact of Microbial Metabolites on Microbiota-Gut-Brain Axis in Inflammatory Bowel Disease

The complex bidirectional communication system existing between the gastrointestinal tract and the brain initially termed the "gut-brain axis" and renamed the "microbiota-gut-brain axis", considering the pivotal role of gut microbiota in sustaining local and systemic homeostasis, has a fundamental role in the pathogenesis of Inflammatory Bowel Disease (IBD). The integration of signals deriving from the host neuronal, immune, and endocrine systems with signals deriving from the microbiota may influence the development of the local inflammatory injury and impacts also more distal brain regions, underlying the psychophysiological vulnerability of IBD patients. Mood disorders and increased response to stress are frequently associated with IBD and may affect the disease recurrence and severity, thus requiring an appropriate therapeutic approach in addition to conventional anti-inflammatory treatments. This review highlights the more recent evidence suggesting that alterations of the microbiota-gut-brain bidirectional communication axis may concur to IBD pathogenesis and sustain the development of both local and CNS symptoms. The participation of the main microbial-derived metabolites, also defined as "postbiotics", such as bile acids, short-chain fatty acids, and tryptophan metabolites in the development of IBD-associated gut and brain dysfunction will be discussed. The last section covers a critical evaluation of the main clinical evidence pointing to the microbiome-based therapeutic approaches for the treatment of IBD-related gastrointestinal and neuropsychiatric symptoms.

Overtraining Syndrome as a Complex Systems Phenomenon

The phenomenon of reduced athletic performance following sustained, intense training (Overtraining Syndrome, and OTS) was first recognized more than 90 years ago. Although hundreds of scientific publications have focused on OTS, a definitive diagnosis, reliable biomarkers, and effective treatments remain unknown. The present review considers existing models of OTS, acknowledges the individualized and sport-specific nature of signs/symptoms, describes potential interacting predisposing factors, and proposes that OTS will be most effectively characterized and evaluated via the underlying complex biological systems. Complex systems in nature are not aptly characterized or successfully analyzed using the classic scientific method (i.e., simplifying complex problems into single variables in a search for cause-and-effect) because they result from myriad (often non-linear) concomitant interactions of multiple determinants. Thus, this review 1) proposes that OTS be viewed from the perspectives of complex systems and network physiology, 2) advocates for and recommends that techniques such as trans-omic analyses and machine learning be widely employed, and 3) proposes evidence-based areas for future OTS investigations, including concomitant multi-domain analyses incorporating brain neural networks, dysfunction of hypothalamic-pituitary-adrenal responses to training stress, the intestinal microbiota, immune factors, and low energy availability. Such an inclusive and modern approach will measurably help in prevention and management of OTS.

From "Leaky Gut" to Impaired Glia-Neuron Communication in Depression

In the last three decades, the robust scientific data emerged, demonstrating that the immune-inflammatory response is a fundamental component of the pathophysiology of major depressive disorder (MDD). Psychological stress and various inflammatory comorbidities contribute to such immune activation. Still, this is not uncommon that patients with depression do not have defined inflammatory comorbidities, and alternative mechanisms of immune activation need to take place. The gastrointestinal (GI) tract, along with gut-associated lymphoid tissue (GALT), constitutes the largest lymphatic organ in the human body and forms the biggest surface of contact with the external environment. It is also the most significant source of bacterial and food-derived antigenic material. There is a broad range of reciprocal interactions between the GI tract, intestinal microbiota, increased intestinal permeability, activation of immune-inflammatory response, and the CNS that has crucial implications in brain function and mental health. This intercommunication takes place within the microbiota-gut-immune-glia (MGIG) axis, and glial cells are the main orchestrator of this communication. A broad range of factors, including psychological stress, inflammation, dysbiosis, may compromise the permeability of this barrier. This leads to excessive bacterial translocation and the excessive influx of food-derived antigenic material that contributes to activation of the immune-inflammatory response and depressive psychopathology. This chapter summarizes the role of increased intestinal permeability in MDD and mechanisms of how the "leaky gut" may contribute to immune-inflammatory response in this disorder.

Endotoxemia coupled with heightened inflammation predicts future depressive symptoms

OBJECTIVE

Cross-sectional data have linked gut barrier abnormalities and endotoxemia with depression, even among those without gastrointestinal symptoms. This study examined longitudinal associations between endotoxemia markers and depressive symptoms, as well as the role of inflammation in this relationship.

DESIGN

At three annual visits, 315 women (n=209 breast cancer survivors, n = 106 non-cancer patient controls, M=55 years old) completed the Center for Epidemiological Studies Depression questionnaire (CES-D) and provided blood samples to assess inflammatory markers - interleukin-6, tumor necrosis factor-alpha, and C-reactive protein - and endotoxemia markers - lipopolysaccharide-binding protein (LBP), soluble CD14 (sCD14), and their ratio.

RESULTS

Adjusting for key demographic variables, health behaviors, visit 1 depressive symptoms, and cancer status and treatment, women with higher visit 1 LBP and LBP/sCD14 had more depressive symptoms at the two subsequent annual visits. Illustrating the notable impact, a woman at the 75th percentile for LBP or LBP/sCD14 at visit 1 was 18 % more likely to report clinically significant depressive symptoms (CES-D ≥16) at follow-up than a woman in the lowest quartile. Cancer status and treatment type did not modulate this relationship. In contrast, visit 1 depressive symptoms did not predict endotoxemia at follow-up. A significant interaction between LBP/sCD14 and inflammatory burden suggested that visit 1 endotoxemia fueled depressive symptoms only in the context of elevated inflammation.

CONCLUSION

These results suggest that endotoxemia, combined with systemic inflammation, can drive depressive symptoms. These findings may implicate bacterial endotoxin translocation from the gut to the bloodstream in depression etiology. Interventions that reduce endotoxemia and inflammation may lessen the risk of depression.

Crocin-I alleviates the depression-like behaviors probably via modulating "microbiota-gut-brain" axis in mice exposed to chronic restraint stress

BACKGROUND

Depressive disorder is rapidly advancing in the worldwide, and therapeutic strategy through "gut-brain" axis has been proved to be effective. Crocin, has been found to have antidepressant activity. However, there is no thorough research for the effects of crocin-I (a major active component of crocin) on depression and its underlying mechanism.

METHODS

We investigated the antidepressant effect of six-week oral administration of crocin-I in a mice model of depression induced by four-week CRS. Based on the "microbiota-gut-brain" axis, we determined the effects of crocin-I administration on gut microbiota, intestinal barrier function, short chain fatty acids and neurochemical indicators.

RESULTS

Administration of crocin-I at a dose of 40 mg/kg for six weeks mitigated depression-like behaviors of depressed mice as evidenced by behaviors tests. In addition, crocin-I reduced the levels of lipopolysaccharide (LPS), Interleukin-6and tumor necrosis factor-α (TNF-α) in serum and TNF-α expression in the hippocampus, and increased the hippocampal brain-derived neurotrophic factor. Besides, 16 s rRNA sequencing revealed that crocin-I mitigated the gut microbiota dysbiosis in depressed mice as represented by the decreased abundance of Proteobacteria and Bacteroidetes, Sutterella spp. and Ruminococcus spp. and increased abundances of Firmicutes, Lactobacillus spp. and Bacteroides spp. Moreover, gas chromatography-mass spectrometry revealed that crocin-I reversed the decreased levels of short-chain fatty acids (SCFAs) in feces of depressed mice. Furthermore, crocin-I improved the impaired intestinal barrier by increasing expression of Occludin and Claudin-1, which contributed to the decreased LPS leakage.

LIMITATIONS

Only the male mice were used; the dose-effect relationship should be observed.

CONCLUSION

These results suggested that crocin-I effectively alleviated depression-like behavior, likely depended on the gut microbiota and its modulation of intestinal barrier and SCFAs.

Naltrexone modulates contextual processing in depression

Context, the information surrounding an experience, can significantly alter the meaning and the affective responses to events. Yet the biological mechanisms through which context modulate experiences are not entirely understood. Here, we hypothesized that the µ-opioid system-extensively implicated in placebo effects, a clinical phenomenon thought to rely on contextual processing-modulates the effects of contextual information on emotional attributions in patients with depression. To test this hypothesis, 20 unmedicated patients with depression completed a randomized, double-blind, placebo-controlled, crossover study of one dose of 50 mg of naltrexone, or placebo immediately before completing two sessions of the Contextual Framing fMRI task. This task captures effects of valenced contextual cues (pleasant vs. unpleasant) on emotional attribution (the rating of subtle emotional faces: fearful, neutral, or happy). Behaviorally, we found that emotional attribution was significantly moderated by the interaction between contextual cues and subtle emotional faces, such that participants' ratings of valenced faces (fearful and happy), compared to neutral, were more negative during unpleasant, compared to pleasant context cues. At a neural level, context-induced blood-oxygen-level-dependent responses in the ventromedial prefrontal cortex, the dorsal anterior cingulate, the dorsolateral prefrontal cortex, and the lateral orbitofrontal cortex, significantly moderated the effects of context on emotional attribution, and were blunted by naltrexone. Furthermore, the effects of naltrexone on emotional attribution were partially abolished in more severely depressed patients. Our results provide insights into the molecular alterations underlying context representation in patients with depression, providing pivotal early data for future treatment studies.

The Changes in 1H-MRS Metabolites in Cuprizone-Induced Model of Multiple Sclerosis: Effects of Prior Psychological Stress

Stress is considered as an important risk factor in the progression and the onset of many disorders such as multiple sclerosis. However, metabolite changes as a result of demyelination under the detrimental effects of stress are not well understood. Thus, 36 female Wistar rats (i.e., groups (1) no-cuprizone (Cont), (2) no-stress + cuprizone-treated (Cup), (3) physical stress + cuprizone-treated (P-Cup), (4) psychological stress + cuprizone-treated (Psy-Cup), (5) physical stress + no-cuprizone-treated (P), (6) psychological stress + no-cuprizone-treated (Psy)) were used in this study. Following induction of repetitive stress, cuprizone treatment was carried out for 6 weeks to instigate demyelination in all groups except the control animal. Relative metabolite concentrations of the brain were investigated by single-voxel proton magnetic resonance spectroscopy (reporting N-acetyl-aspartate (NAA), glycerophosphocholine with phosphocholine (tCho) relative to total creatine (tCr)). According to ¹H-MRS, rats in the Cup group indicated a reduction in NAA/ tCr (p < 0.001) as well as tCho/ tCr (p < 0.05) compared with that in the Cont group. In contrast, in both stress + cuprizone-treated groups, NAA/tCr and tCho/tCr ratios remarkably increased versus the Cup group (p < 0.001) and the Cont group (p < 0.001 for the Psy-Cup group and p < 0.05 for the P-Cup group). Both P and Psy groups revealed normal metabolite concentrations similar to the Cont group 6 weeks post stress. Seemingly, in the case of cuprizone alone, decreased level of metabolites is mainly relevant to neuronal cell impairments. Meanwhile, as a result of oxidative stress enhancement due to stress exposure, oligodendrocyte becomes the main victim indicating the increased level of metabolite ratios.

Potential Roles of Myeloid Differentiation Factor 2 on Neuroinflammation and Its Possible Interventions

Neuroinflammation is the primary response by immune cells in the nervous system to protect against infection. Chronic and uncontrolled neuroinflammation triggers neuronal injury and neuronal death resulting in a variety of neurodegenerative disorders. Therefore, fine tuning of the immune response in the nervous system is now extensively considered as a potential therapeutic intervention for those diseases. The immune cells of the nervous system express Toll-like receptor 4 (TLR4) together with myeloid differentiation factor 2 (MD-2) to protect against the pathogens. Over the last 10 years, antagonists targeting the functional domains of MD-2 have become attractive pharmacological intervention strategies in pre-clinical studies into neuroinflammation and its associated brain pathologies. This review aims to summarize and discuss the roles of TLR4-MD-2 signaling pathway activation in various models of neuroinflammation. This review article also highlights the studies reporting the effect of MD-2 antagonists on neuroinflammation in in vitro and in vivo studies.

The innate immune toll-like-receptor-2 modulates the depressogenic and anorexiolytic neuroinflammatory response in obstructive sleep apnoea

The increased awareness of obstructive sleep apnoea’s (OSA) links to Alzheimer’s disease and major psychiatric disorders has recently directed an intensified search for their potential shared mechanisms. We hypothesised that neuroinflammation and the microglial TLR2-system may act as a core process at the intersection of their pathophysiology. Moreover, we postulated that inflammatory-response might underlie development of key behavioural and neurostructural changes in OSA. Henceforth, we set out to investigate effects of 3 weeks’ exposure to chronic intermittent hypoxia in mice with or without functional TRL2 (TLR2^+/+, C57BL/6-Tyrc-Brd-Tg(Tlr2-luc/gfp)Kri/Gaj;TLR2^−/−,C57BL/6-Tlr2tm1Kir). By utilising multimodal imaging in this established model of OSA, a discernible neuroinflammatory response was demonstrated for the first time. The septal nuclei and forebrain were shown as the initial key seed-sites of the inflammatory cascade that led to wider structural changes in the associated neurocircuitry. Finally, the modulatory role for the functional TLR2-system was suggested in aetiology of depressive, anxious and anorexiolytic symptoms in OSA.

Increased brain vitamin D receptor expression and decreased expression of cathelicidin antimicrobial peptide in individuals who died by suicide

Vitamin D deficiency is associated with immune dysregulation, increased vulnerability to infections, depression, and suicidal behavior. One mediator of vitamin D-dependent immune regulation and antimicrobial defense is the cathelicidin antimicrobial peptide (LL-37), encoded by the cathelicidin-related antimicrobial peptide (CRAMP) gene. We compared the mRNA expression of the CRAMP gene, the vitamin D receptor (VDR) gene, as well as the CYP27B1 and CYP24A1 genes (involved in vitamin D metabolism) in the dorsolateral prefrontal cortex (dlPFC) and anterior cingulate cortex (ACC) between depressed individuals who died by suicide (n = 15) and matched (age, gender, and post-mortem interval) non-psychiatric controls (n = 15). Gene expression was measured through qRT-PCR with TaqMan® primers and probes, with GAPDH and β-actin genes as endogenous controls. Statistical analyses included t-tests and Pearson correlations. CRAMP mRNA expression was downregulated and VDR mRNA expression was upregulated in both dlPFC and ACC in suicides relative to controls, with no significant differences in expression of CYP24A1 and CYP27B1. To our knowledge, this is the first study on brain cathelicidin expression in the human brain in relationship to suicide. Increased VDR and decreased CRAMP expression are consistent with previously reported associations between vitamin D deficiency, immune dysregulation, and suicidal behavior, and should lead to future studies uncovering novel interactive targets for suicide prevention.

Depletion of brain perivascular macrophages regulates acute restraint stress-induced neuroinflammation and oxidative/nitrosative stress in rat frontal cortex

The central nervous system can respond to peripheral immune stimuli through the activation of the neurovascular unit. One of the cellular types implicated are perivascular macrophages (PVMs), hematopoietic-derived brain-resident cells located in the perivascular space. PVMs have been implicated in the immune surveillance and in the regulation of the accumulation/trafficking of macromolecules in brain-blood interfaces. Recent studies suggested that the role of PVMs could vary depending on the nature and duration of the immune challenge applied. Here, we investigate the role of PVMs in stress-induced neuroinflammation and oxidative/nitrosative consequences. The basal phagocytic activity of PVMs was exploited to selectively deplete them by ICV injection of liposomes encapsulating the pro-apoptotic drug clodronate. Acute restraint stress-induced neuroinflammation and oxidative/nitrosative stress in rat brain frontal cortex samples were assessed by western blot and RT-PCR analyses. The depletion of PVMs: (1) decreased tumor necrosis-α levels (2) prevented the Janus kinase/signal transducers and activators of transcription pathway and increased interleukin-6 receptor protein-expression in stress conditions; (3) prevented the stress-induced Toll-like receptor 4/Myeloid differentiation primary response 88 protein signaling pathway; (4) down-regulated the pro-inflammatory nuclear factor κB/cyclooxygenase-2 pathway; (5) prevented stress-induced lipid peroxidation and the concomitant increase of the endogenous antioxidant mediators nuclear factor (erythroid-derived 2)-like 2, glutathione reductase 1 and Parkinsonism-associated deglycase mRNA expression. Our results point to PVMs as regulators of stress-induced neuroinflammation and oxidative/nitrosative stress. Much more scientific effort is still needed to evaluate whether their selective manipulation is promising as a therapeutic strategy for the treatment of stress-related neuropsychopathologies.

Cellular mechanisms and molecular signaling pathways in stress-induced anxiety, depression, and blood-brain barrier inflammation and leakage

Depression and anxiety are comorbid conditions in many neurological or psychopathological disorders. Stress is an underlying event that triggers development of anxiety and depressive-like behaviors. Recent experimental data indicate that anxiety and depressive-like behaviors occurring as a result of stressful situations can cause blood-brain barrier (BBB) dysfunction, which is characterized by inflammation and leakage. However, the underlying mechanisms are not completely understood. This paper sought to review recent experimental preclinical and clinical data that suggest possible molecular mechanisms involved in development of stress-induced anxiety and depression with associated BBB inflammation and leakage. Critical therapeutic targets and potential pharmacological candidates for treatment of stress-induced anxiety and depression with associated BBB dysfunctions are also discussed.

Stress-induced blood brain barrier disruption: Molecular mechanisms and signaling pathways

Stress is a nonspecific response to a threat or noxious stimuli with resultant damaging consequences. Stress is believed to be an underlying process that can trigger central nervous system disorders such as depression, anxiety, and post-traumatic stress disorder. Though the pathophysiological basis is not completely understood, data have consistently shown a pivotal role of inflammatory mediators and hypothalamo-pituitary-adrenal (HPA) axis activation in stress induced disorders. Indeed emerging experimental evidences indicate a concurrent activation of inflammatory signaling pathways and not only the HPA axis, but also, peripheral and central renin-angiotensin system (RAS). Furthermore, recent experimental data indicate that the HPA and RAS are coupled to the signaling of a range of central neuro-transmitter, -mediator and -peptide molecules that are also regulated, at least in part, by inflammatory signaling cascades and vice versa. More recently, experimental evidences suggest a critical role of stress in disruption of the blood brain barrier (BBB), a neurovascular unit that regulates the movement of substances and blood-borne immune cells into the brain parenchyma, and prevents peripheral injury to the brain substance. However, the mechanisms underlying stress-induced BBB disruption are not exactly known. In this review, we summarize studies conducted on the effects of stress on the BBB and integrate recent data that suggest possible molecular mechanisms and signaling pathways underlying stress-induced BBB disruption. Key molecular targets and pharmacological candidates for treatment of stress and related illnesses are also summarized.