Targeting IL-1 in depression

Post-COVID Trajectory of Pentraxin 3 Plasma Levels Over 6 Months and Their Association with the Risk of Developing Post-Acute Depression and Anxiety

BACKGROUND AND OBJECTIVES

Clinical manifestations of coronavirus disease 2019 (COVID-19) often persist after acute disease resolution. Underlying molecular mechanisms are unclear. The objective of this original article was to longitudinally measure plasma levels of markers of the innate immune response to investigate whether they associate with and predict post-COVID symptomatology.

METHODS

Adult patients with previous severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection during the first pandemic wave who underwent the 6-month multidisciplinary follow-up were included. Plasma levels of pentraxin 3 (PTX3), the complement components C3a and C5a, and chitinase-3 like-protein-1 (CHI3L1) were measured at hospital admission during acute disease (baseline) and at 1 and 6 months after hospital discharge. Associations with post-COVID-19 sequelae at 6 months were investigated using descriptive statistic and multiple regression models.

RESULTS

Ninety-four COVID-19 patients were included. Baseline PTX3, C5a, C3a, and CHI3L1 did not predict post-COVID-19 sequelae. The extent of the reduction of PTX3 over time (delta PTX3) was associated with lower depressive and anxiety symptoms at 6 months (both p < 0.05). When entering sex, age, need for intensive care unit or non-invasive ventilation during hospital stay, psychiatric history, and baseline PTX3 as nuisance covariates into a generalized linear model (GLM), the difference between baseline and 6-month PTX3 levels (delta PTX3) significantly predicted depression (χ2 = 4.66, p = 0.031) and anxiety (χ2 = 4.68, p = 0.031) at 6 months. No differences in PTX3 levels or PTX3 delta were found in patients with or without persistent or new-onset other COVID-19 symptoms or signs at 6 months. Plasma levels of C3a, C5a, and CHI3L1 did not correlate with PTX3 levels at either time point and failed to associate with residual or de novo respiratory or systemic clinical manifestations of the disease at 6 months.

CONCLUSIONS

A lower reduction of plasma PTX3 after acute COVID-19 associates with the presence of depression and anxiety, suggesting an involvement of inflammation in post-COVID-19 psychopathology and a potential role of PTX3 as a biomarker.

Annual Research Review: Neuroimmune network model of depression: a developmental perspective

Depression is a serious public health problem, and adolescence is an 'age of risk' for the onset of Major Depressive Disorder. Recently, we and others have proposed neuroimmune network models that highlight bidirectional communication between the brain and the immune system in both mental and physical health, including depression. These models draw on research indicating that the cellular actors (particularly monocytes) and signaling molecules (particularly cytokines) that orchestrate inflammation in the periphery can directly modulate the structure and function of the brain. In the brain, inflammatory activity heightens sensitivity to threats in the cortico-amygdala circuit, lowers sensitivity to rewards in the cortico-striatal circuit, and alters executive control and emotion regulation in the prefrontal cortex. When dysregulated, and particularly under conditions of chronic stress, inflammation can generate feelings of dysphoria, distress, and anhedonia. This is proposed to initiate unhealthy, self-medicating behaviors (e.g. substance use, poor diet) to manage the dysphoria, which further heighten inflammation. Over time, dysregulation in these brain circuits and the inflammatory response may compound each other to form a positive feedback loop, whereby dysregulation in one organ system exacerbates the other. We and others suggest that this neuroimmune dysregulation is a dynamic joint vulnerability for depression, particularly during adolescence. We have three goals for the present paper. First, we extend neuroimmune network models of mental and physical health to generate a developmental framework of risk for the onset of depression during adolescence. Second, we examine how a neuroimmune network perspective can help explain the high rates of comorbidity between depression and other psychiatric disorders across development, and multimorbidity between depression and stress-related medical illnesses. Finally, we consider how identifying neuroimmune pathways to depression can facilitate a 'next generation' of behavioral and biological interventions that target neuroimmune signaling to treat, and ideally prevent, depression in youth and adolescents.

The effect of Vortioxetine on the NLRP3 pathway and microglial activity in the prefrontal cortex in an experimental model of depression

BACKGROUND

Increasing evidence suggests that early life stress (ELS) and neuroinflammation are associated with the pathophysiology of depression. The purpose of this study was to determine the effects of Vortioxetine (VOR), a novel antidepressant, on ELS-induced behavioral changes and neuroinflammation.

METHOD

Wistar Albino 4-week-old male rats were divided into four groups: control; chronic unpredictable stress (CUMS), VOR, CUMS + VOR. Neurobehavioral assessment was performed on the first, 21st, and 42nd days. RT-PCR was used to detect the expression of P2X7, NLRP3, IL1β, IL18 in the prefrontal cortex. To assess the microglial activities of the prefrontal cortex, immunohistochemically stained CD68, and leukocyte common antigen (LCA) preparations were scanned with Manual WSI software, Basler camera, and scored.

RESULT AND DISCUSSION

Exposure to CUMS was associated with depression and anxiety-like behaviors, and administration of VOR led to improvement in these behaviors. NLRP3, IL-1β, and IL-18 were shown to be upregulated in the prefrontal cortex of CUMS rats, while their high expression was inhibited by VOR treatment. CD68 and LCA expressions were significantly higher in the CUMS group compared to the other groups.

CONCLUSION

According to these results, it may be considered that NLRP3 inflammasome-associated neuroinflammatory response and microglial activation may play a role in the etiopathogenesis of ELS.

Methamphetamine (MA) use and MA-induced psychosis are associated with increasing aberrations in the compensatory immunoregulatory system, interleukin-1α, and CCL5 levels

There are only a few studies reporting on the immunological profiles of methamphetamine (MA) use, MA dependency, or MA-induced psychosis (MAP). This study measured M1 macrophage, T helper (Th)-1, Th-2, growth factor, and chemokine profiles, as well as the immune inflammatory response system (IRS) and compensatory immunoregulatory system (CIRS) in peripheral blood samples from patients with MA use (n = 51), MA dependence (n = 47), and MAP (n = 43) in comparison with controls (n = 32). We discovered that persistent MA use had a robust immunosuppressive impact on all immunological profiles. The most reliable biomarker profile of MA use is the combination of substantial CIRS suppression and a rise in selected pro-inflammatory cytokines, namely CCL27 (CTACK), CCL11 (eotaxin), and interleukin (IL)-1α. In addition, MA dependency is associated with increased immunosuppression, as demonstrated by lower stem cell factor levels and higher IL-10 levels. MAP is related to a significant decrease in all immunological profiles, particularly CIRS, and an increase in CCL5 (RANTES), IL-1α, and IL-12p70 signaling. In conclusion, long-term MA use and dependency severely undermine immune homeostasis, whereas MAP may be the consequence of increased IL-1α - CCL5 signaling superimposed on strongly depleted CIRS and Th-1 functions. The widespread immunosuppression established in longstanding MA use may increase the likelihood of infectious and immune illness or exacerbate disorders such as hepatitis and AIDS. Furthermore, elevated levels of CCL5, CCL11, CCL27, IL-1α, and/or IL-12p70 may play a role in the peripheral (atherosclerosis, cutaneous inflammation, immune aberrations, hypospermatogenesis) and central (neuroinflammation, neurotoxic, neurodegenerative, depression, anxiety, and psychosis) side effects of MA use.

Identification of novel immune-related biomarker and therapeutic drugs in Parkinson disease via integrated bioinformatics analysis

BACKGROUND

The present study was designed to identify immune-related biomarker and candidate drugs for Parkinson disease (PD) by weighted gene co-expression network analysis.

METHODS

Differentially expressed genes were identified in PD and healthy samples in the Gene Expression Omnibus (GEO) database. Besides, immune-related genes were obtained from the immunology database. Then, a co-expression network was constructed by the weighted gene co-expression network analysis package. Diagnostic model for PD was constructed by Lasso and multivariate Cox regression. Furthermore, differentially expressed genes (DEGs) were used to establish PPI and competing endogenous RNA (ceRNA) networks. Functional enrichment and pathway analysis were performed. Drug-hub gene interaction analysis was performed via DGIdb database.

RESULTS

PD samples and normal samples were found to have 220 upregulated genes and 216 downregulated genes in the GSE6613 dataset. The differentially expressed genes contained 50 immune-related genes, with 40 upregulated genes and 10 downregulated genes. We obtained 7 hub genes by intersecting the DEGs and candidate hub genes. As potential diagnostic markers, 2 immune-related DEGs were identified among the 7 hub genes. According to functional enrichment analysis, these DEGs were mainly enriched in immune response, inflammatory response, and cytokine-cytokine receptor interactions. Totally, we obtained 182 drug-gene interaction pairs in Drug-Gene Interaction database (DGIdb).

CONCLUSION

Our results revealed crucial genes and candidate drugs for PD patients and deepen our understanding of the molecular mechanisms involved in PD.

Garlic essential oil ameliorates depression-like behaviors in unpredictable chronic mild stress by modulating the brain NLRP3 inflammasome pathway and influencing the gut barrier and microbiota

Depression is a severe mental disorder, with approximately 300 million people suffering from it. Recent studies have demonstrated that chronic neuroinflammation is significantly associated with intestinal flora and barrier function in depression. As a therapeutic herb, garlic (Allium sativum L.) has detoxification, antibacterial activity, and antiinflammatory functions; however, its antidepressant effect through gut microbiota and barrier function has not been reported yet. The present study investigated the effect of garlic essential oil (GEO) and its active constituent diallyl disulfide (DADS) on depressive behavior by attenuating the NLRP3 inflammasome, alternating intestinal barrier function and gut microbiota in an unpredictable chronic mild stress (US) model in rats. This study found that dopamine and serotonin turnover rates were reduced significantly with a low dose of GEO (25 mg per kg bw). The GEO groups effectively reversed sucrose preference and increased the total distance traveled in the behavioral test. Moreover, 25 mg per kg bw GEO inhibited the UCMS-induced activated inflammatory response, reflected by reduced expression in the frontal cortex of NLRP3, ASC, caspase-1, and its downstream IL-1β proteins, as well as the concentration of IL-1β and TNF-α in the serum. Supplementation with GEO increased the expression of occludin and ZO-1 and the concentration of short-chain fatty acids to influence the impact of intestinal permeability in depressive conditions. The results revealed that GEO administration caused significant changes in the α and β diversity and abundance of certain bacteria. At the genus level, GEO administration significantly increased the relative abundance, particularly beneficial SCFA-producing bacteria, and may improve depression-like behavior. In conclusion, these results indicated the antidepressant effects of GEO involved in the inflammatory pathway, short-chain fatty acids, intestinal integrity, and intestinal composition.

Beyond an inflammatory mediator: Interleukin-1 in neurophysiology

NEW FINDINGS

What is the topic of this review? This review focuses on the physiological role of the cytokine interleukin-1β in the CNS. What advances does it highlight? Traditionally, interleukin-1β is known as a key mediator of inflammation and immunity. This review highlights the more recent findings describing how interleukin-1β signalling is required to maintain homeostasis in the CNS.

ABSTRACT

Since its discovery in the early 1940s, the interleukin-1 (IL-1) cytokine family has been associated primarily with acute and chronic inflammation. The family member IL-1β is produced by different leucocytes, endothelial cells and epithelial cells. This cytokine has been characterized as a key modulator of inflammation and innate immunity because it induces the transcription of several downstream inflammatory genes. More recently, several groups have demonstrated that IL-1β production is also required to maintain homeostasis in several organ systems. This review focuses on providing an overview of the more recently characterized role of IL-1β in the physiology of the CNS. So far, IL-1β signalling has been implicated in neuronal survival, neurite growth, synaptic pruning, synaptic transmission, neuroplasticity and neuroendocrine functions.

Microglial NLRP3 inflammasome activation mediates diabetes-induced depression-like behavior via triggering neuroinflammation

BACKGROUND

Abundant evidence suggests that the prevalence and risk of depression in people with diabetes is high. However, the pathogenesis of diabetes-related depression remains unclear. Since neuroinflammation is associated with the pathophysiology of diabetic complications and depression, this study aims to elucidate the neuroimmune mechanism of diabetes-related depression.

METHODS

Male C57BL/6 mice were injected with streptozotocin to establish a diabetes model. After screening, diabetic mice were treated with the NLRP3 inhibitor MCC950. Then, metabolic indicators and depression-like behaviors were evaluated in these mice, as well as their central and peripheral inflammation. To explore the mechanism of high glucose-induced microglial NLRP3 inflammasome activation, we performed in vitro studies focusing on its canonical upstream signal I (TLR4/MyD88/NF-κB) and signal II (ROS/PKR/P₂X₇R/TXNIP).

RESULTS

Diabetic mice exhibited depression-like behaviors and activation of NLRP3 inflammasome in hippocampus. In vitro high-glucose (50 mM) environment primed microglial NLRP3 inflammasome by promoting NF-κB phosphorylation in a TLR4/MyD88-independent manner. Subsequently, high glucose activated the NLRP3 inflammasome via enhancing intracellular ROS accumulation, upregulating P₂X₇R, as well as promoting PKR phosphorylation and TXNIP expression, thereby facilitating the production and secretion of IL-1β. Inhibition of NLRP3 with MCC950 significantly restored hyperglycemia-induced depression-like behavior and reversed the increase in IL-1β levels in the hippocampus and serum.

CONCLUSION

The activation of NLRP3 inflammasome, probably mainly in hippocampal microglia, mediates the development of depression-like behaviors in STZ-induced diabetic mice. Targeting the microglial inflammasome is a feasible strategy for the treatment of diabetes-related depression.

Affective neural circuits and inflammatory markers linked to depression and anxiety symptoms in patients with comorbid obesity

Although we have effective treatments for depression and anxiety, we lack mechanistic understanding or evidence-based strategies to tailor these treatments in the context of major comorbidities such as obesity. The current feasibility study uses functional neuroimaging and biospecimen data to determine if changes in inflammatory markers, fecal short-chain fatty acids, and neural circuit-based targets can predict depression and anxiety outcomes among participants with comorbid obesity. Blood and stool samples and functional magnetic resonance imaging data were obtained at baseline and 2 months, during the parent ENGAGE-2 trial. From 30 participants with both biospecimen and fMRI data, this subsample study explored the relationship among changes in inflammatory markers and fecal short-chain fatty acids and changes in neural targets, and their joint relationship with depression and anxiety symptoms. Bivariate and partial correlation, canonical correlation, and partial least squares analyses were conducted, with adjustments for age, sex, and treatment group. Initial correlation analyses revealed three inflammatory markers (IL-1RA, IL-6, and TNF-α) and five neural targets (in Negative Affect, Positive Affect, and Default Mode Circuits) with significantly associated changes at 2 months. Partial least squares analyses then showed that changes in IL-1RA and TNF-α and changes in three neural targets (in Negative Affect and Positive Affect Circuits) at 2 months were associated with changes in depression and anxiety symptoms at 6 months. This study sheds light on the plausibility of incorporation of inflammatory and gastrointestinal biomarkers with neural targets as predictors of depression and comorbid anxiety outcomes among patients with obesity.

Major depressive disorder (mdd): emerging immune targets at preclinical level

BACKGROUND

Major depressive disorder is a mental health disorder that is characterized by a persistently low mood and loss of interest. MDD is affecting over 3.8% of the global population as a major health problem. Its etiology is complex, and involves the interaction between a number of factors, including genetic predisposition and the presence of environmental stresses.

AREAS COVERED

The role of the immune and inflammatory systems in depression has been gaining interest, with evidence suggesting the potential involvement of pro-inflammatory molecules like TNF, interleukins, prostaglandins, and other cytokines, among others, has been put forth. Along with this, the potential of agents, from NSAIDs to antibiotics, are being evaluated in therapy for depression. The current review will discuss emerging immune targets at the preclinical level.

EXPERT OPINION

With increasing evidence to show that immune and inflammatory mediators are implicated in MDD, increasing research toward their potential as drug targets is encouraged. At the same time, agents acting on these mediators and possessing anti-inflammatory potential are also being evaluated as future therapeutic options for MDD, and increasing focus toward non-conventional drugs which can act through these mechanisms is important as regards the future prospects of the use of anti-inflammatory agents in depression.

Graves' disease as a driver of depression: a mechanistic insight

Graves' disease (GD) is characterized by diffuse enlargement and overactivity of the thyroid gland, which may be accompanied by other physical symptoms. Among them, depression can dramatically damage patients' quality of life, yet its prevalence in GD has not received adequate attention. Some studies have established a strong correlation between GD and increased risk of depression, though the data from current study remains limited. The summary of mechanistic insights regarding GD and depression has underpinned possible pathways by which GD contributes to depression. In this review, we first summarized the clinical evidence that supported the increased prevalence of depression by GD. We then concentrated on the mechanistic findings related to the acceleration of depression in the context of GD, as mounting evidence has indicated that GD promotes the development of depression through various mechanisms, including triggering autoimmune responses, inducing hormonal disorders, and influencing the thyroid-gut-microbiome-brain axis. Finally, we briefly presented potential therapeutic approaches to decreasing the risk of depression among patients with GD.

Transcriptome Alterations Caused by Social Defeat Stress of Various Durations in Mice and Its Relevance to Depression and Posttraumatic Stress Disorder in Humans: A Meta-Analysis

The research on molecular causes of stress-associated psychopathologies is becoming highly important because the number of people with depression, generalized anxiety disorder and posttraumatic stress disorders (PTSDs) is steadily increasing every year. Investigation of molecular mechanisms in animal models opens up broad prospects for researchers, but relevant molecular signatures can differ significantly between patients and animal models. In our work, we for the first time carried out a meta-analysis of transcriptome changes in the prefrontal cortex of C57BL/6 mice after 10 and 30 days of social defeat stress (SDS). We then examined possible correlations of these alterations with transcriptome changes found in post-mortem samples from patients with depression or PTSD. Although transcriptional signatures of human psychiatric disorders and SDS did not overlap substantially, our results allowed us to identify the most reproducible changes seen after SDS of various durations. In addition, we were able to identify the genes involved in susceptibility to SDS after 10 days of stress. Taken together, these data help us to elucidate the molecular changes induced by SDS depending on its duration as well as their relevance to the alterations found in depression or PTSD in humans.

Inflammatory pathophysiological mechanisms implicated in postpartum depression

Postpartum Depression (PPD) is a serious psychiatric disorder of women within the first year after delivery. It grievously damages women's physical and mental health. Inflammatory reaction theory is well-established in depression, and also has been reported associated with PPD. This review summarized the inflammatory pathophysiological mechanisms implicated in PPD, including decreased T cell activation, increased proinflammatory cytokines secretion, active kynurenine pathway, and initiated NLRP3 inflammasome. Clinical and preclinical research are both gathered. Potential therapeutical alternatives targeting the inflammatory mechanisms of PPD were introduced. In addition, this review briefly discussed the differences of inflammatory mechanisms between PPD and depression. The research of inflammation in PPD is limited and seems just embarking, which indicates the direction we can further study. As a variety of risky factors contribute to PPD collectively, therapy for women with PPD should be comprehensive, and clinical heterogeneity should be taken into consideration. As PPD has a predictability, early clinical screening and interventions are also needed. This review aims to help readers better understand the inflammatory pathological mechanisms in PPD, so as to identify biomarkers and potential therapeutic targets in the future.

Repetitive Transcranial Magnetic Stimulation for the Treatment of Resistant Depression: A Scoping Review

Treatment-resistant depression (TRD) is associated with significant disability, and due to its high prevalence, it results in a substantive socio-economic burden at a global level. TRD is the inability to accomplish and/or achieve remission after an adequate trial of antidepressant treatments. Studies comparing repetitive transcranial magnetic stimulation (rTMS) with electroconvulsive therapy (ECT) and pharmacotherapy have revealed evidence of the therapeutic efficacy of rTMS in TRD. These findings suggest a crucial role for rTMS in the management of TRD. This article aims to conduct a comprehensive scoping review of the current literature concerning the use of rTMS and its therapeutic efficacy as a treatment modality for TRD. PubMed, PsycINFO, Medline, Embase, and Cinahl were used to identify important articles on rTMS for TRD. The search strategy was limited to English articles within the last five years of data publication. Articles were included if they reported on a completed randomized controlled trial (RCT) of rTMS intervention for TRD. The exclusion criteria involved studies with rTMS for the treatment of conditions other than TRD, and study and experimental protocols of rTMS on TRD. In total, 17 studies were eligible for inclusion in this review. The search strategy spanned studies published in the last five years, to the date of the data search (14 February 2022). The regional breakdown of the extracted studies was North American (n = 9), European (n = 5), Asian (n = 2) and Australian (n = 1). The applied frequencies of rTMS ranged from 5 Hz to 50 Hz, with stimulation intensities ranging from 80% MT to 120% MT. Overall, 16 out of the 17 studies suggested that rTMS treatment was effective, safe and tolerated in TRD. For patients with TRD, rTMS appears to provide significant benefits through the reduction of depressive symptoms, and while there is progressive evidence in support of the same, more research is needed in order to define standardized protocols of rTMS application in terms of localization, frequency, intensity, and pulse parameters.

Melatonergic Receptors (Mt1/Mt2) as a Potential Additional Target of Novel Drugs for Depression

A complex pathogenesis involving several physiological systems is theorized to underline the development of depressive disorders. Depression is accompanied by circadian regulation disruption and interaction with the functioning of both central and peripheral oscillators. Many aspects of melatonin function unite these systems. The use of drugs for circadian rhythm disorders could inspire a potential treatment strategy for depression. Melatonin plays an essential role in the regulation of circadian rhythms. It exerts effect by activating two types of melatonin receptors, type 1A (MT1) and 1B (MT2). These are G-protein-coupled receptors, predominantly located in the central nervous system. MT1/MT2 agonists could be a useful treatment approach according to all three prevalent theories of the pathogenesis of depression involving either monoamines, synaptic remodeling, or immune/inflammatory events. MT1/MT2 receptors can be a potential target for novel antidepressants with impact on concentrations of neurotrophins or neurotransmitters, and reducing levels of pro-inflammatory cytokines. There is an interesting cross-talk mediated via the physical association of melatonin and serotonin receptors into functional heteromers. The antidepressive and neurogenetic effects of MT1/MT2 agonists can also be caused by the inhibition of the acid sphingomyelinase, leading to reduced ceramide, or increasing monoamine oxidase A levels in the hippocampus. Compounds targeting MT1 and MT2 receptors could have potential for new anti-depressants that may improve the quality of therapeutic interventions in treating depression and relieving symptoms. In particular, a combined effect on MT1 and/or MT2 receptors and neurotransmitter systems may be useful, since the normalization of the circadian rhythm through the melatonergic system will probably contribute to improved treatment. In this review, we discuss melatonergic receptors as a potential additional target for novel drugs for depression.

Delirium due to hip fracture is associated with activated immune-inflammatory pathways and a reduction in negative immunoregulatory mechanisms

BACKGROUND

The objectives of this study were to delineate whether delirium in older adults is associated with activation of the immune-inflammatory response system (IRS) as indicated by activation of M1, T helper (Th)1, and Th17 profiles, and/or by reduced activities of the compensatory immunoregulatory system (CIRS), including Th2 and T regulatory profiles.

METHODS

We recruited 65 older adult patients with a low energy impact hip fracture who underwent hip fracture operation. The CAM-ICU and the Delirium Rating Scale, Revised-98-Thai version (DRS-R-98) were assessed pre-operatively and 1, 2 and 3 days after surgery. Blood samples (day 1 and 2) post-surgery were assayed for cytokines/chemokines using a MultiPlex assay and the neutrophil/lymphocyte ratio.

RESULTS

We found that delirium and/or the DRS-R-98 score were associated with IRS activation as indicated by activated M1, Th1, Th17 and T cell growth profiles and by attenuated CIRS functions. The most important IRS biomarkers were CXCL8, interleukin (IL)-6, and tumor necrosis factor-α, and the most important CIRS biomarkers were IL-4 and soluble IL-1 receptor antagonist. We found that 42.5% of the variance in the actual changes in the DRS-R-98 score (averaged from day 1 to day 3) was explained by T cell growth factors, baseline DRS-R-98 scores and age. An increase in the NLR reflects overall IRS, M1, Th1, Th17, and Th2 activation.

CONCLUSIONS

Post-hip surgery delirium is associated with activated IRS pathways and appears especially in patients with lowered CIRS functions.

Neuropsychiatric symptoms and seizure related with serum cytokine in epilepsy patients

Neuroinflammation contributes to epileptogenesis and ictogenesis. Various signals of neuroinflammation lead to neuronal hyper-excitability. Since an interplay between epilepsy, psychiatric comorbidities and neuroinflammation has been suggested, we explored psychiatric symptoms in epilepsy patients, and the relationship with neuroinflammation. We screened epilepsy patients who were admitted for video-EEG monitoring between July 2019 and December 2020. Enrolled patients were asked to respond to neuropsychiatric questionnaires (Hospital Anxiety and Depression Scale (HADS) and Neuropsychiatric Inventory-Questionnaire (NPI-Q)) on admission. Serum cytokines (IL-1β, IL-2, IL-6, IFN-γ, CCL2, and CCL5) were measured by ELISA on admission, and within 6 h after a seizure. We enrolled 134 patients, and 32 patients (23.9%) had seizures during monitoring. Cytokine levels did not change after seizures, but IL-2 and IL-6 increased in cases of generalized tonic–clonic seizures. The HADS-A score was lower in Q4 of CCL5 (p-value = 0.016) and anxiety was also less common in Q4 of CCL5 (p-value = 0.042). NPI-Q question 4 (depression) severity was higher in CCL2 (p-value = 0.024). This suggested that psychiatric symptoms may also be related to inflammatory processes in epilepsy patients. Further large, standardized studies are necessary to underpin the inflammatory mechanisms in epilepsy and psychiatric symptoms.

The Impact of SARS-CoV-2 Infection on Youth Mental Health: A Narrative Review

Background: COVID-19 pandemic has affected the physical health, psychological wellbeing, and mental health of the whole population. Young people are among those most at risk of developing mental health symptoms or disorders related to the pandemic. Purpose: the present narrative review is aimed at providing an updated overview of the current literature concerning the psychological impact of the SARS-CoV-2 infection but also of the COVID-19 outbreak, environmental restriction, and social distancing on mental health outcomes among the youth population aged between 15 and 25 years. Methods: in December 2021, an electronic search on this topic was performed on PubMed. Relevant publications from January 2020 until December 2021 were included. Findings: 53 cross-sectional studies, 26 longitudinal studies, 4 ecological studies, 1 qualitative study, and 1 systematic review were included. We found many methodological limitations in the studies included, especially poor choice of study samples and short follow-ups. Little literature was in support of a strong relationship between SARS-CoV-2 infection and consequences on youth mental health. On the contrary, many studies showed how extraordinary measures to limit the spread of the virus have impacted young people in terms of onset of new mental disorders and symptoms, suicidality, and access to emergency psychiatric services. Depressive and anxiety symptoms and disorders show the greatest increase in incidence, especially in girls and young women. Conclusions: it seems important to pay attention to the mental health of young people in relation to the consequences of the COVID-19 pandemic. However, studies with more robust methodologies and longer follow-ups are needed to establish precise indications for targeted interventions in this context.

No increase in inflammation in late-life major depression screened to exclude physical illness

Depression is a common and debilitating disorder in the elderly. Late-life depression (LLD) has been associated with inflammation and elevated levels of proinflammatory cytokines including interleukin (IL)-1β, tumor necrosis factor-alpha, and IL-6, but often depressed individuals have comorbid medical conditions that are associated with immune dysregulation. To determine whether depression has an association with inflammation independent of medical illness, 1120 adults were screened to identify individuals who had clinically significant depression but not medical conditions associated with systemic inflammation. In total, 66 patients with LLD screened to exclude medical conditions associated with inflammation were studied in detail along with 26 age-matched controls (HC). At baseline, circulating cytokines were low and similar in LLD and HC individuals. Furthermore, cytokines did not change significantly after treatment with either an antidepressant (escitalopram 20 mg/day) or an antidepressant plus a COX-2 inhibitor or placebo, even though depression scores improved in the non-placebo treatment arms. An analysis of cerebrospinal fluid in a subset of individuals for IL-1β using an ultrasensitive digital enzyme-linked immunosorbent assay revealed low levels in both LLD and HC at baseline. Our results indicate that depression by itself does not result in systemic or intrathecal elevations in cytokines and that celecoxib does not appear to have an adjunctive antidepressant role in older patients who do not have medical reasons for having inflammation. The negative finding for increased inflammation and the lack of a treatment effect for celecoxib in this carefully screened depressed population taken together with multiple positive results for inflammation in previous studies that did not screen out physical illness support a precision medicine approach to the treatment of depression that takes the medical causes for inflammation into account.

The role of alcohol use and adiposity in serum levels of IL-1RA in depressed patients

BACKGROUND

The role of Interleukin-1 Receptor antagonist (IL-1Ra), an innate antagonist to pro-inflammatory cytokine IL-1, has attracted increasing attention due to its potential pathogenic and therapeutic implications in depression. However, the role of alcohol and adiposity in modulating IL-1Ra cytokine pathway in depressed patients has remainned unknown. The aim of this study was to follow the changes in IL-1Ra serum levels in depressed patients with or without simultaneous alcohol use disorder (AUD) and different degrees of adiposity during 6 months of follow-up.

MATERIALS AND METHODS

A total of 242 patients with depression were followed for 6 months. At baseline 99 patients had simultaneous AUD. Levels of serum IL-1Ra and common mediators of inflammation (IL-6, hs-CRP) were measured. Clinical assessments included Body Mass Index (BMI), Montgomery-Asberg Depression Rating Scale (MADRS) and Alcohol Use Disorders Identification Test (AUDIT) scores.

RESULTS

Significant reductions in clinical symptoms and IL-1Ra were observed during 6-month follow-up. In hierarchical linear regression analysis, the effect of MADRS score, age, gender, and smoking had a combined effect of 2.4% in the model. The effect of AUDIT score increased the effect to 4.2% of variance (p = 0.08), whereas adding BMI increased the effect to 18.5% (p <  0.001).

CONCLUSION

Adiposity may influence the IL-1Ra anti-inflammatory response in depressed patients, whereas the effect of alcohol consumption in these patients seems insignificant. These findings should be considered in studies on the role of IL-1Ra in depression.

TRIAL REGISTRATION

Ostrobothnia Depression Study in ClinicalTrials.gov , Identifier NCT02520271 .

Microglia and their LAG3 checkpoint underlie the antidepressant and neurogenesis-enhancing effects of electroconvulsive stimulation

Despite evidence implicating microglia in the etiology and pathophysiology of major depression, there is paucity of information regarding the contribution of microglia-dependent molecular pathways to antidepressant procedures. In this study, we investigated the role of microglia in a mouse model of depression (chronic unpredictable stress-CUS) and its reversal by electroconvulsive stimulation (ECS), by examining the effects of microglia depletion with the colony stimulating factor-1 antagonist PLX5622. Microglia depletion did not change basal behavioral measures or the responsiveness to CUS, but it completely abrogated the therapeutic effects of ECS on depressive-like behavior and neurogenesis impairment. Treatment with the microglia inhibitor minocycline concurrently with ECS also diminished the antidepressant and pro-neurogenesis effects of ECS. Hippocampal RNA-Seq analysis revealed that ECS significantly increased the expression of genes related to neurogenesis and dopamine signaling, while reducing the expression of several immune checkpoint genes, particularly lymphocyte-activating gene-3 (Lag3), which was the only microglial transcript significantly altered by ECS. None of these molecular changes occurred in microglia-depleted mice. Immunohistochemical analyses showed that ECS reversed the CUS-induced changes in microglial morphology and elevation in microglial LAG3 receptor expression. Consistently, either acute or chronic systemic administration of a LAG3 monoclonal antibody, which readily penetrated into the brain parenchyma and was found to serve as a direct checkpoint blocker in BV2 microglia cultures, rapidly rescued the CUS-induced microglial alterations, depressive-like symptoms, and neurogenesis impairment. These findings suggest that brain microglial LAG3 represents a promising target for novel antidepressant therapeutics.

Role of amygdala in stress-induced upregulation of airway IL-1 signaling in asthma

Psychological stress, an important contributor to asthma morbidity, potentiates the immune response to allergen, but the brain mechanisms mediating this response are not fully understood. The amygdala is likely to play an important role, given its sensitivity to threat and connectivity with descending immune modulatory pathways. In this study, we recruited thirty asthmatic participants and examined glucose metabolism in the amygdala, using [F-18]fluorodeoxyglucose positron emission tomography, during a laboratory stressor. Stress hormone and airway inflammatory measurements were also acquired. Results showed that activity in the amygdala was significantly increased during the stressor, compared to a matched control task (p < .05 corrected). Moreover, the increase in amygdala activity was associated with a greater increase in sputum IL-1R1 mRNA and alpha amylase response (p < .05 corrected), which were also positively correlated (p = .01). These findings suggest that heightened amygdala reactivity may contribute to asthma morbidity via descending proinflammatory sympathetic signaling pathways.

A single dose of ketamine cannot prevent protracted stress-induced anhedonia and neuroinflammation in rats

Worldwide, millions of people suffer from treatment-resistant depression. Ketamine, a glutamatergic receptor antagonist, can have a rapid antidepressant effect even in treatment-resistant patients. A proposed mechanism for the antidepressant effect of ketamine is the reduction of neuroinflammation. To further explore this hypothesis, we investigated whether a single dose of ketamine can modulate protracted neuroinflammation in a repeated social defeat (RSD) stress rat model, which resembles features of depression. To this end, male animals exposed to RSD were injected with ketamine (20 mg/kg) or vehicle. A combination of behavioral analyses and PET scans of the inflammatory marker TSPO in the brain were performed. Rats submitted to RSD showed anhedonia-like behavior in the sucrose preference test, decreased weight gain, and increased TSPO levels in the insular and entorhinal cortices, as observed by [¹¹C]-PK11195 PET. Whole brain TSPO levels correlated with corticosterone levels in several brain regions of RSD exposed animals, but not in controls. Ketamine injection 1 day after RSD disrupted the correlation between TSPO levels and serum corticosterone levels, but had no effect on depressive-like symptoms, weight gain or the protracted RSD-induced increase in TSPO expression in male rats. These results suggest that ketamine does not exert its effect on the hypothalamic-pituitary-adrenal axis by modulation of neuroinflammation.

Significance of Brain Glucose Hypometabolism, Altered Insulin Signal Transduction, and Insulin Resistance in Several Neurological Diseases

Several neurological diseases share pathological alterations, even though they differ in their etiology. Neuroinflammation, altered brain glucose metabolism, oxidative stress, mitochondrial dysfunction and amyloidosis are biological events found in those neurological disorders. Altered insulin-mediated signaling and brain glucose hypometabolism are characteristic signs observed in the brains of patients with certain neurological diseases, but also others such as type 2 diabetes mellitus and vascular diseases. Thus, significant reductions in insulin receptor autophosphorylation and Akt kinase activity, and increased GSK-3 activity and insulin resistance, have been reported in these neurological diseases as contributing to the decline in cognitive function. Supporting this relationship is the fact that nasal and hippocampal insulin administration has been found to improve cognitive function. Additionally, brain glucose hypometabolism precedes the unmistakable clinical manifestations of some of these diseases by years, which may become a useful early biomarker. Deficiencies in the major pathways of oxidative energy metabolism have been reported in patients with several of these neurological diseases, which supports the hypothesis of their metabolic background. This review remarks on the significance of insulin and brain glucose metabolism alterations as keystone common pathogenic substrates for certain neurological diseases, highlighting new potential targets.

Anti-Inflammatory Effects of Curcumin in the Inflammatory Diseases: Status, Limitations and Countermeasures

Curcumin is a natural compound with great potential for disease treatment. A large number of studies have proved that curcumin has a variety of biological activities, among which anti-inflammatory effect is a significant feature of it. Inflammation is a complex and pervasive physiological and pathological process. The physiological and pathological mechanisms of inflammatory bowel disease, psoriasis, atherosclerosis, COVID-19 and other research focus diseases are not clear yet, and they are considered to be related to inflammation. The anti-inflammatory effect of curcumin can effectively improve the symptoms of these diseases and is expected to be a candidate drug for the treatment of related diseases. This paper mainly reviews the anti-inflammatory effect of curcumin, the inflammatory pathological mechanism of related diseases, the regulatory effect of curcumin on these, and the latest research results on the improvement of curcumin pharmacokinetics. It is beneficial to the further study of curcumin and provides new ideas and insights for the development of curcumin anti-inflammatory preparations.

The role of the host microbiome in autism and neurodegenerative disorders and effect of epigenetic procedures in the brain functions

Autism Spectrum Disorder (ASD) is a severe neurological/neurodegenerative syndrome that results in cognitive and communication disorders. The degree of dysbiosis is related to the severity of ASD signs. The gut is conferred with a variety of sensory receptors that cooperate with effector systems including the endocrine, nervous and gut immune systems of the intestine. Gut dysbiosis causes amplified inflammation, the launch of the HPA axis, changed levels of neurotransmitters and bacterial metabolites; these may donate to abnormal signaling throughout the Vagus nerve in ASD. Decreased integrity of the gastrointestinal barrier led to extreme leakage of substances as of the intestine in early life and inflammation followed by disruption of BBB integrity maybe increase the risk of ASD. Microbiota, by controlling the barrier permeability, regulate the quantity and types of bioactive materials that are transferred from the intestine to the brain. Exposure to metabolites and microbial products regulate significant procedures in the CNS, including glial cell role, myelination, synaptic pruning, and play a role in neurobehavioral, neurodegenerative, psychiatric, and metabolic syndrome.

Lycopene and Chrysin through Mitigation of Neuroinflammation and Oxidative Stress Exerted Antidepressant Effects in Clonidine-Induced Depression-like Behavior in Rats

Depression is a severely debilitating psychiatric disorder that influences more than 15% of the population worldwide. It has been demonstrated that it is associated with a high risk of developing other diseases such as cardiovascular diseases, diabetes, stroke, epilepsy, and cancer. The current study examines the possibility of chrysin and lycopene having an antidepressant effect in a rat model of depression induced by clonidine, as well as the mechanisms underlying this effect, including the role of neuroinflammation and oxidative stress. Rats were allotted into seven groups. The rats in group 1 served as a control. Group 2 received lycopene only. Group 3 was provided chrysin only. Group 4 was administered clonidine and served as the model. Group 5 was offered lycopene and clonidine. Group 6 was administered chrysin and clonidine. Group 7 was given FLX and clonidine and represented the standard. The experiment lasted two weeks, during which behavioral, biochemical, histopathological, and immunohistochemical measurements were performed. Lycopene and chrysin were used to correct the concentrations of noradrenaline and serotonin hippocampal tissue concentrations. These findings were also improved by immunohistochemical analysis of GFAP, VEGF, caspase3, and histopathological examinations, in which pretreatment of rats with lycopene and chrysin reversed all clonidine-induced alterations. The current research demonstrates that lycopene and chrysin have an auspicious antidepressant effect against clonidine that provoked behavioral hopelessness in rats. Manipulating oxidative stress, inflammation, and apoptosis may partially represent the corrective mechanism for the neuroprotective actions against the depressive effect of clonidine.

Glial PAMPering and DAMPening of Adult Hippocampal Neurogenesis

Adult neurogenesis represents a mature brain's capacity to integrate newly generated neurons into functional circuits. Impairment of neurogenesis contributes to the pathophysiology of various mood and cognitive disorders such as depression and Alzheimer's Disease. The hippocampal neurogenic niche hosts neural progenitors, glia, and vasculature, which all respond to intrinsic and environmental cues, helping determine their current state and ultimate fate. In this article we focus on the major immune communication pathways and mechanisms through which glial cells sense, interact with, and modulate the neurogenic niche. We pay particular attention to those related to the sensing of and response to innate immune danger signals. Receptors for danger signals were first discovered as a critical component of the innate immune system response to pathogens but are now also recognized to play a crucial role in modulating non-pathogenic sterile inflammation. In the neurogenic niche, viable, stressed, apoptotic, and dying cells can activate danger responses in neuroimmune cells, resulting in neuroprotection or neurotoxicity. Through these mechanisms glial cells can influence hippocampal stem cell fate, survival, neuronal maturation, and integration. Depending on the context, such responses may be appropriate and on-target, as in the case of learning-associated synaptic pruning, or excessive and off-target, as in neurodegenerative disorders.

Increased prevalence of attention-deficit hyperactivity disorder symptomatology in patients with familial Mediterranean fever

OBJECTIVES

Previous studies suggest that exposure to inflammation in infancy may increase the risk for attention-deficit and hyperactivity disorder (ADHD). We studied the ADHD manifestations among 124 familial Mediterranean fever (FMF) patients and examined the relationship between FMF patient characteristics and ADHD.

METHODS

Clinical, demographic, and genetic data were abstracted from patients' medical records and supplemented by information obtained during clinic visits. ADHD manifestations were assessed using the Diagnostic and Statistical Manual of Mental Disorders (5th ed.) questionnaire.

RESULTS

ADHD was diagnosed in 42 (32.8%) FMF patients, a rate significantly higher than in unselected populations (∼8%). A majority (n = 27, 64.3%) had combined inattentive, hyperactive-impulsive manifestations. Eight (19%) had predominantly hyperactive-impulsive, and seven (16.6%) had predominantly inattentive symptoms. FMF patients with severe manifestations reported more ADHD symptoms. FMF patients with ADHD symptoms were less adherent to their treatment regimen, with only 61.9% of the patients with ADHD symptoms adhering to colchicine therapy compared to 92.7% of the patients without ADHD symptoms.

CONCLUSION

The high prevalence of ADHD characteristics in children with FMF may support the neuroimmune hypothesis that chronic inflammation increases the risk for ADHD. Children with FMF should be screened for ADHD as its presence may adversely affect adherence to treatment.

Menhaden fish oil attenuates postpartum depression in rat model via inhibition of NLRP3-inflammasome driven inflammatory pathway

Background and aim

Postpartum depression (PPD) is a familiar problem which is associated with about 10–20% of women after child delivery. Fish oil (FO) has a therapeutic potentials to many diseases including mood disorders. However, there is paucity of data on the effects of FO supplementation on PPD rat model. Hence, this study aimed at investigating the potentials of FO in ameliorating depressive-like behaviors in PPD rat by evaluating the involvement of NLRP3-inflammasome.

Experimental procedure

Thirty six virgin adult female rats (n = 6) were randomly divided into six groups; Group 1–3 were normal control (NC), Sham (SHAM) and ovariectomized group (OVX) respectively whereas group 4–6 were PPD rats forced-fed once daily with distilled water (PPD), fish oil (PPD + FO; 9 g/kg) and Fluoxetine (PPD + FLX; 15 mg/kg) respectively from postpartum day 1 and continued for 10 consecutive days. Rats behaviors were evaluated on postpartum day 10 through open field test (OFT) and forced swimming test (FST), followed by biochemical analysis of NLRP3 inflammasome proteins pathway in their brain and determination of neutrophil to lymphocyte ratio (NLR).

Results

PPD-induced rats exhibited high immobility and low swimming time in FST with increased inflammatory status; NLR, IL-1β and NFкB/NLRP3/caspase-1 activity in their hippocampus. However, administration of FO or fluoxetine reversed the aforementioned abnormalities.

Conclusion

In conclusion, 10 days supplementation with FO ameliorated the depressive-like behaviors in PPD rats by targeting the NFкB/NLRP3/caspase-1/IL-1β activity. This has shed light on the potential of NLRP3 as a therapeutic target in treatment of PPD in rats.

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Pioneer study on 10 days effect of Menhaden fish oil in post partum depression rat model.

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Menhaden fish oil attenuates post partum depression in rat model.

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Menhanden fish oil acted through NLRP3 inflammasome pathways.

Statins: Neurobiological underpinnings and mechanisms in mood disorders

Statins (3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors) treat dyslipidaemia and cardiovascular disease by inhibiting cholesterol biosynthesis. They also have immunomodulatory and anti-inflammatory properties. Beyond cardiovascular disease, cholesterol and inflammation appear to be components of the pathogenesis and pathophysiology of neuropsychiatric disorders. Statins may therefore afford some therapeutic benefit in mood disorders. In this paper, we review the pathophysiology of mood disorders with a focus on pharmacologically relevant pathways, using major depressive disorder and bipolar disorder as exemplars. Statins are discussed in the context of these disorders, with particular focus on the putative mechanisms involved in their anti-inflammatory and immunomodulatory effects. Recent clinical data suggest that statins may have antidepressant properties, however given their interactions with many known biological pathways, it has not been fully elucidated which of these are the major determinants of clinical outcomes in mood disorders. Moreover, it remains unclear what the appropriate dose, or appropriate patient phenotype for adjunctive treatment may be. High quality randomised control trials in concert with complementary biological investigations are needed if the potential clinical effects of statins on mood disorders, as well as their biological correlates, are to be better understood.

Quercetin hinders microglial activation to alleviate neurotoxicity via the interplay between NLRP3 inflammasome and mitophagy

Activated microglia are an important type of innate immune cell in the brain, and they secrete inflammatory cytokines into the extracellular milieu, exert neurotoxicity to surrounding neurons and are involved in the pathogenesis of many brain disorders. Quercetin (Qu), a natural flavonoid, is known to have anti-inflammatory and antioxidant properties. Previous studies have shown that both increased reactive oxygen species (ROS) stress and decreased autophagy participate in the activation of microglial. In the current study, we showed that Qu significantly attenuated LPS-induced inflammatory factor production, cell proliferation and NF-κB activation of microglia. Importantly, Qu decreased the levels of NLR family, pyrin domain containing three (NLRP3) inflammasome and pyroptosis-related proteins, including NLRP3, active caspase-1, GSDMD N-terminus and cleaved IL-1β. Further study indicated that this anti-inflammatory effect of Qu was associated with mitophagy regulation. Importantly, Qu promoted mitophagy to enhance damaged mitochondrial elimination, which then reduced mtROS accumulation and alleviated NLRP3 inflammasome activation. Then, we confirmed that Qu treatment protected primary neurons against LPS-induced microglial toxicity and alleviated neurodegeneration in both depression and PD mouse models. Further IL-1β administration blunted these neuroprotective effects of Qu in vitro and in vivo. This work illustrated that Qu prevents neuronal injury via inhibition of mtROS-mediated NLRP3 inflammasome activation in microglia through promoting mitophagy, which provides a potential novel therapeutic strategy for neuroinflammation-related diseases.

Chronic ethanol exposure induced depressive-like behavior in male C57BL/6 N mice by downregulating GluA1

Chronic ethanol exposure can increase the risk of depression. The α-amino-3‑hydroxy-5-methyl-4-isoxazole-propionic acid (AMPA) receptor is a key factor in depression and its treatment. The study was conducted to investigate the depressive-like behavior induced by chronic ethanol exposure in mice and to explore the mechanism in cells. To establish the chronic ethanol exposure mouse model, male C57BL/6 N mice were administered 10% (m/V) and 20% (m/V) ethanol as the only choice for drinking for 60 days, 90 days and 180 days. Depressive-like behavior in mice was confirmed by the forced swimming test (FST). Ethanol-induced changes in the mouse hippocampus were indicated by Western blotting, qPCR and Fluoro-Jade C (FJC) staining. We confirmed that 90- and 180-day ethanol exposure can lead to depressive-like mouse behavior, cell apoptosis, neuronal degeneration, a reduction in GluA1 and brain-derived neurotrophic factor (BDNF) expression, and an increase in IL-6 and IL-1β in the mouse hippocampus. GluA1 silencing and overexpression models of SH-SY5Y cells were established for further investigation. The cells were treated with 100 mM and 200 mM ethanol for 24 h. Ethanol exposure decreased cell viability and the expression of BDNF and increased the cell apoptosis rate and the expression of BAX, cleaved caspase-3, IL-1β and IL-6. GluA1 silencing aggravated ethanol-induced changes in cell viability and apoptosis and the expression of BDNF, BAX and cleaved caspase-3, and GluA1 overexpression attenuated these changes. Neither the silencing nor overexpression of GluA1 had an effect on ethanol-induced increases in IL-1β and IL-6. Our results indicated that chronic ethanol exposure induced depressive-like behavior in male C57BL/6 N mice by downregulating GluA1 expression.

Astrocytic and Oligodendrocytic P2X7 Receptors Determine Neuronal Functions in the CNS

P2X7 receptors are members of the ATP-gated cationic channel family with a preferential localization at the microglial cells, the resident macrophages of the brain. However, these receptors are also present at neuroglia (astrocytes, oligodendrocytes) although at a considerably lower density. They mediate necrosis/apoptosis by the release of pro-inflammatory cytokines/chemokines, reactive oxygen species (ROS) as well as the excitotoxic (glio)transmitters glutamate and ATP. Besides mediating cell damage i.e., superimposed upon chronic neurodegenerative processes in Alzheimer’s Disease, Parkinson’s Disease, multiple sclerosis, and amyotrophic lateral sclerosis, they may also participate in neuroglial signaling to neurons under conditions of high ATP concentrations during any other form of neuroinflammation/neurodegeneration. It is a pertinent open question whether P2X7Rs are localized on neurons, or whether only neuroglia/microglia possess this receptor-type causing indirect effects by releasing the above-mentioned signaling molecules. We suggest as based on molecular biology and functional evidence that neurons are devoid of P2X7Rs although the existence of neuronal P2X7Rs cannot be excluded with absolute certainty.

Higher baseline interleukin-1β and TNF-α hamper antidepressant response in major depressive disorder

Raised pro-inflammatory immune/inflammatory setpoints, leading to an increased production of peripheral cytokines, have been associated with Major Depressive Disorder (MDD) and with failure to respond to first-line antidepressant drugs. However, the usefulness of these biomarkers in clinical psychopharmacology has been questioned because single findings did not translate into the clinical practice, where patients are prescribed treatments upon clinical need. We studied a panel of 27 inflammatory biomarkers in a sample of 108 inpatients with MDD, treated with antidepressant monotherapy for 4 weeks upon clinical need in a specialized hospital setting, and assessed the predictive effect of baseline peripheral measures of inflammation on antidepressing efficacy (response rates and time-lagged pattern of decrease of depression severity) using a machine-learning approach with elastic net penalized regression, and multivariate analyses in the context of the general linear model. When considering both categorical and continuous measures of response, baseline levels of IL-1β predicted non-response to antidepressants, with the predicted probability to respond being highly dispersed at low levels of IL-1β, and stratifying toward non-response when IL-1β is high. Significant negative effects were also detected for TNF-α, while IL-12 weakly predicted response. These findings support the usefulness of inflammatory biomarkers in the clinical psychopharmacology of depression, and add to ongoing research efforts aiming at defining reliable cutoff values to identify depressed patients in clinical settings with high inflammation, and low probability to respond.

N-Acetylcysteine Rescues Hippocampal Oxidative Stress-Induced Neuronal Injury via Suppression of p38/JNK Signaling in Depressed Rats

Progression of neuronal deterioration within specific brain regions is considered as one of the principal bases for the development of major depressive disorders. Therefore, protects and promotes the maintaining of normal structure and function of neurons might be a potential therapeutic strategy in the treatment of depression. Here, we report that the antioxidant, N-acetylcysteine (NAC), inhibited neuronal injury through its capacity to reduce oxidative stress and exerted antidepressant effects. Specifically, we show that antioxidant enzyme activity was significantly decreased in the hippocampal CA1 region of depressive rats, while treatment with NAC (300 mg/kg, i.p.) produced neuroprotective effects against mitochondrial oxidative stress injuries and oxidative DNA damage in CA1 neurons of these rats. Moreover, NAC treatment alleviated neuronal injury resulting from neuroinflammation and apoptosis in depressed rats, effects that were associated with reductions in dendritic spine atrophy, and synapse deficits. These effects appear to involve a down-regulation of p38 mitogen-activated protein kinase (MAPK)-JNK signaling along with an up-regulation of ERK signaling within the hippocampal CA1 region. Moreover, this NAC treatment significantly ameliorated depression-like behaviors as indicated by performance in the sucrose preference and forced swim tests (FST). Taken together, these results reveal the potential involvement of oxidative stress in the generation of depression. And, the antidepressant-like effects exerted by NAC may involve reductions in this oxidative stress that can result in neuronal deterioration. Such neuroprotective effects of NAC may indicate a potential therapeutic strategy for the treatment of stress-related depression.

Nonesterified Fatty Acids and Depression in Cancer Patients and Caregivers

BACKGROUND

Nonesterified fatty acids (NEFAs) are known to have inflammatory effects. The inflammatory hypothesis of depression suggests that omega-3 (ω-3) and omega-6 (ω-6) fatty acids might be negatively and positively correlated with depression, respectively.

OBJECTIVE

An exploratory study was conducted to determine the association between dietary free fatty acids and depressive symptoms in cancer patients and caregivers.

METHODS

Associations between depression and the NEFA pool were investigated in 56 cancer patients and 23 caregivers using a combination of nonparametric tests and regularized regression. Plasma NEFAs were measured using thin layer and gas chromatography with flame ionization detection. Depression was characterized both as a continuous severity score using the GRID-Hamilton Depression Rating Scale (GRID Ham-D), and as a categorical diagnosis of major depression by structured clinical interview.

RESULTS

Initial hypotheses regarding the relation between depression and omega-3 or omega-6 fatty acids were not well supported. However, elaidic acid, a trans-unsaturated fatty acid found in hydrogenated vegetable oils, was found to be negatively correlated with continuous depression scores in cancer patients. No significant associations were found in caregivers.

CONCLUSIONS

An unexpected negative association between elaidic acid and depression was identified, supporting recent literature on the role of G protein-coupled receptors in depression. Further research is needed to confirm this result and to evaluate the potential role of G protein agonists as therapeutic agents for depression in cancer patients.

Kynurenine regulates NLRP2 inflammasome in astrocytes and its implications in depression

Increased kynurenine (Kyn) metabolized from tryptophan (Try) is a biomarker in the immune dysfunction of depression. However, the mechanism by which Kyn change promotes depression is poorly defined. Astrocytes are involved in the neuroinflammation of depression. Among the numerous inflammatory cytokines, interleukin-1β (IL-1β) produced by astrocytic Nod-like receptor protein (NLRP) inflammasome is crucial in the pathogenesis of depression. In the present study, Kyn was shown to be a proinflammatory metabolite in the neuroimmune signaling network mediating depressive-like behavior. First, in chronic mild stress (CMS)-induced depressive mice, the level of Kyn notably increased in the hippocampus, accompanied by the activation of astrocytic NLRP2 inflammasome. Kyn treatment specifically upregulated Nod-like receptor protein 2 (NLPR2) expression in primary mouse astrocytes. Kyn + ATP activated NLRP2 inflammasome, evidenced by increased caspase-1 expression and IL-1β release. After Kyn treatment, nuclear factor kappa-B (NF-κB) could translocate to the nucleus and bind the promoter of NLRP2, subsequently increased NLRP2 transcription in cultured astrocytes in vitro. Intraperitoneal injection of Kyn activated NLRP2 inflammasome in astrocytes of hippocampus in mice, while NLRP2 knockdown in astrocytes abolished depressive-like behaviors in mice induced by Kyn, suggesting the critical role of NLRP2 in Kyn-induced depression. These findings demonstrate a novel mechanism that Kyn upregulates NLRP2 in an NF-κB-dependent pathway and provide a new strategy for treatment of depression.

Acute exposure to low-level light at night is sufficient to induce neurological changes and depressive-like behavior

The advent and wide-spread adoption of electric lighting over the past century has profoundly affected the circadian organization of physiology and behavior for many individuals in industrialized nations; electric lighting in homes, work environments, and public areas have extended daytime activities into the evening, thus, increasing night-time exposure to light. Although initially assumed to be innocuous, chronic exposure to light at night (LAN) is now associated with increased incidence of cancer, metabolic disorders, and affective problems in humans. However, little is known about potential acute effects of LAN. To determine whether acute exposure to low-level LAN alters brain function, adult male, and female mice were housed in either light days and dark nights (LD; 14 h of 150 lux:10 h of 0 lux) or light days and low level light at night (LAN; 14 h of 150 lux:10 h of 5 lux). Mice exposed to LAN on three consecutive nights increased depressive-like responses compared to mice housed in dark nights. In addition, female mice exposed to LAN increased central tendency in the open field. LAN was associated with reduced hippocampal vascular endothelial growth factor-A (VEGF-A) in both male and female mice, as well as increased VEGFR1 and interleukin-1β mRNA expression in females, and reduced brain derived neurotrophic factor mRNA in males. Further, LAN significantly altered circadian rhythms (activity and temperature) and circadian gene expression in female and male mice, respectively. Altogether, this study demonstrates that acute exposure to LAN alters brain physiology and can be detrimental to well-being in otherwise healthy individuals.

Pathological ATPergic Signaling in Major Depression and Bipolar Disorder

The mood disorders, major depression (MD) and bipolar disorder (BD), have a high lifetime prevalence in the human population and accordingly generate huge costs for health care. Efficient, rapidly acting, and side-effect-free pharmaceuticals are hitherto not available, and therefore, the identification of new therapeutic targets is an imperative task for (pre)clinical research. Such a target may be the purinergic P2X7 receptor (P2X7R), which is localized in the central nervous system (CNS) at microglial and neuroglial cells mediating neuroinflammation. MD and BD are due to neuroinflammation caused in the first line by the release of the pro-inflammatory cytokine interleukin-1β (IL-1β) from the microglia. IL-1β in turn induces the secretion of corticotropin-releasing hormone (CRH) and in consequence the secretion of adrenocorticotropic hormone (ACTH) and cortisol, which together with a plethora of further cytokines/chemokines lead to mood disorders. A number of biochemical/molecular biological measurements including the use of P2X7R- or IL-1β-deficient mice confirmed this chain of events. More recent studies showed that a decrease in the astrocytic release of ATP in the prefrontal cortex and hippocampus is a major cause of mood disorders. It is an attractive hypothesis that compensatory increases in P2X7Rs in these areas of the brain are the immediate actuators of MD and BD. Hence, blood-brain barrier-permeable P2X7R antagonists may be promising therapeutic tools to improve depressive disorders in humans.

The Neuroimmune and Neurotoxic Fingerprint of Major Neurocognitive Psychosis or Deficit Schizophrenia: a Supervised Machine Learning Study

No studies have examined the immune fingerprint of major neurocognitive psychosis (MNP) or deficit schizophrenia using M1 macrophage cytokines in combination with chemokines such as CCL2 and CCL11. The present study delineated the neuroimmune fingerprint of MNP by analyzing plasma levels of IL-1β, sIL-1RA, TNFα, sTNFR1, sTNFR2, CCL2, and CCL11 in 120 MNP versus 54 healthy controls in association with neurocognitive scores (as assessed with the Brief Assessment of Cognition in Schizophrenia) and PHEMN (psychotic, hostility, excitation, mannerism and negative) symptoms. MNP was best predicted by a combination of CCL11, TNFα, IL-1β, and sIL-1RA which yielded a bootstrapped (n = 2000) area under the receiver operating curve of 0.985. Composite scores reflecting M1 macrophage activity and neurotoxic potential including effects of CCL11 and CCL2 were significantly increased in MNP. A large part of the variance in PHEM (38.4-52.6%) and negative (65.8-74.4%) symptoms were explained by combinations of immune markers whereby CCL11 was the most important. The same markers explained a large part of the variance in the Mini-Mental State examination, list learning, digit sequencing task, category instances, controlled word association, symbol coding, and Tower of London. Partial least squares analysis showed that 72.7% of the variance in overall severity of schizophrenia was explained by the regression on IL-1β, sIL-1RA, CCL11, TNFα, and education. It is concluded that the combination of the abovementioned markers defines MNP as a distinct neuroimmune disorder and that increased immune neurotoxicity determines memory and executive impairments and PHEMN symptoms as well.

Chronic intrahippocampal interleukin-1β overexpression in adolescence impairs hippocampal neurogenesis but not neurogenesis-associated cognition

Both neuroinflammation and adult hippocampal neurogenesis (AHN) are implicated in many neurodegenerative disorders as well as in neuropsychiatric disorders, which often become symptomatic during adolescence. A better knowledge of the impact that chronic neuroinflammation has on the hippocampus during the adolescent period could lead to the discovery of new therapeutics for some of these disorders. The hippocampus is particularly vulnerable to altered concentrations of the pro-inflammatory cytokine interleukin-1β (IL-1β), with elevated levels implicated in the aetiology of neurodegenerative disorders such as Alzheimer's and Parkinson's, and stress-related disorders such as depression. The effect of acutely and chronically elevated concentrations of hippocampal IL-1β have been shown to reduce AHN in adult rodents. However, the effect of exposure to chronic overexpression of hippocampal IL-1β during adolescence, a time of increased vulnerability, hasn't been fully interrogated. Thus, in this study we utilized a lentiviral approach to induce chronic overexpression of IL-1β in the dorsal hippocampus of adolescent male Sprague Dawley rats for 5 weeks, during which time its impact on cognition and hippocampal neurogenesis were examined. A reduction in hippocampal neurogenesis was observed along with a reduced level of neurite branching on hippocampal neurons. However, there was no effect of IL-1β overexpression on performance in pattern separation, novel object recognition or spontaneous alternation in the Y maze. Our study has highlighted that chronic IL-1β overexpression in the hippocampus during the adolescent period exerts a negative impact on neurogenesis independent of cognitive performance, and suggests a degree of resilience of the adolescent hippocampus to inflammatory insult.

Novel neuroimmunologic therapeutics in depression: A clinical perspective on what we know so far

Depression, one of the most common mental health disorders, is among the leading causes of health-related disability worldwide. Although antidepressant treatment has been available for decades, depression remains largely refractory to the prevailing limited treatment approach of monoamine transmission modulation. Fortunately, recent evidence points to a link between depression and inflammatory factors within the innate and the adaptive immune system. The purpose of this review is to evaluate current and potential clinical immunotherapies for depression, as contextually focused by an immunologic lens of the pathophysiologic mechanisms of depression. The utility of pro-inflammatory cytokines (primarily interleukin-1β, interleukin -6 and tumor necrosis factor-α) is considered in their role as screening biomarkers in prediction of treatment response or nonresponse. The evidence base of numerous recent clinical studies is discussed as related to their antidepressant efficacy and favorable safety profile, with consideration of multiple agents that target inflammatory mechanisms linked to depression including nonsteroidal anti-inflammatory pathways (i.e., aspirin, celecoxib), cytokine antagonism (i.e., etanercept, infliximab), N-methyl-D-aspartate receptor (NMDA) receptor antagonism (i.e., ketamine), and modulation of kynurenine pathways (i.e., minocycline). Additionally, new and exciting directions in targeting inflammatory mechanisms in the treatment of depression are underway, and future investigation is also warranted to explore the utility of inflammation in diagnosing depression, guiding clinical treatment decision-making, and monitoring disease burden and relapse risk.

Interleukin-6: Its role and mechanisms in rescuing depression-like behaviors in rat models of depression

Neuronal injury within specific brain regions is considered a critical risk factor in the pathophysiology of depression. However, the underlying mechanisms of this process, and thus the potential for development of novel therapeutic strategies in the treatment of depression, remain largely unknown. Here, we report that Il-6 protects against neuronal anomalies related with depression, in part, by suppressing oxidative stress and consequent autophagic and apoptotic hyperactivity. Specifically, we show that IL-6 is downregulated within the CA1 hippocampus in two animal models of depression and upregulated by antidepressants. Increasing levels of IL-6 in the CA1 region result in pleiotropic protective actions including reductions in oxidative stress and modulation of autophagy, anti-immuno-inflammatory activation and anti-apoptotic effects in CA1 neurons, all of which are associated with the rescue of depression-like behaviors. In contrast, IL-6 downregulation exacerbates neuronal anomalies within the CA1 region and facilitates the genesis of depression phenotypes in rats. Interestingly, in addition to attenuating oxidative damage, the antioxidant, N-acetylcysteine (NAC), is also associated with significantly decreased neuronal deficits and the display of depressive behaviors in rats. These results suggest that IL-6 may exert neuroprotection within CA1 neurons via pleiotropic mechanisms and may serve as a potential therapeutic target for the treatment of depression.

The Role of Aberrations in the Immune-Inflammatory Response System (IRS) and the Compensatory Immune-Regulatory Reflex System (CIRS) in Different Phenotypes of Schizophrenia: the IRS-CIRS Theory of Schizophrenia

Several lines of evidence indicate that aberrations in immune-inflammatory pathways may contribute to the pathophysiology of schizophrenia spectrum disorders. Here, we propose a novel theoretical framework that was previously developed for major depression and bipolar disorder, namely, the compensatory immune-regulatory reflex system (CIRS), as applied to the neuro-immune pathophysiology of schizophrenia and its phenotypes, including first-episode psychosis (FEP), acute relapses, chronic and treatment-resistant schizophrenia (TRS), comorbid depression, and deficit schizophrenia. These schizophrenia phenotypes and manifestations are accompanied by increased production of positive acute-phase proteins, including haptoglobin and α2-macroglobulin, complement factors, and macrophagic M1 (IL-1β, IL-6, and TNF-α), T helper (Th)-1 (interferon-γ and IL-2R), Th-2 (IL-4, IL-5), Th-17 (IL-17), and T regulatory (Treg; IL-10 and transforming growth factor (TGF)-β1) cytokines, cytokine-induced activation of the tryptophan catabolite (TRYCAT) pathway, and chemokines, including CCL-11 (eotaxin), CCL-2, CCL-3, and CXCL-8. While the immune profiles in the different schizophrenia phenotypes indicate the activation of the immune-inflammatory response system (IRS), there are simultaneous signs of CIRS activation, including increased levels of the IL-1 receptor antagonist (sIL-1RA), sIL-2R and tumor necrosis factor-α receptors, Th-2 and Treg phenotypes with increased IL-4 and IL-10 production, and increased levels of TRYCATs and haptoglobin, α2-macroglobulin, and other acute-phase reactants, which have immune-regulatory and anti-inflammatory effects. Signs of activated IRS and CIRS pathways are also detected in TRS, chronic, and deficit schizophrenia, indicating that these conditions are accompanied by a new homeostatic setpoint between upregulated IRS and CIRS components. In FEP, increased baseline CIRS activity is a protective factor that may predict favorable clinical outcomes. Moreover, impairments in the CIRS are associated with deficit schizophrenia and greater impairments in semantic and episodic memory. It is concluded that CIRS plays a key role in the pathophysiology of schizophrenia by negatively regulating the primary IRS and contributing to recovery from the acute phase of illness. Therefore, components of the CIRS may offer promising therapeutic targets for schizophrenia.

Role of Chronic Administration of Antidepressant Drugs in the Prenatal Stress-Evoked Inflammatory Response in the Brain of Adult Offspring Rats: Involvement of the NLRP3 Inflammasome-Related Pathway

Evidence indicates that adverse experiences in early life may be a factor for immune disturbances leading to the depression in adulthood. Recently, a pivotal role in the pathogenesis of depression has been assigned to the activation of the brain Nod-like receptor pyrin-containing 3 (NLRP3) inflammasome. We investigated the impact of chronic treatment with antidepressant drugs on the behavioral disturbances and the levels of proinflammatory factors in the hippocampus and frontal cortex of adult male rats after prenatal stress exposure. Next, we explored the involvement of the NLRP3 inflammasome-related pathways in the mechanism of antidepressant action. Our study confirmed that chronic antidepressant treatment attenuated depression-like disturbances and exerted an anxiolytic action. All antidepressants diminished the prenatal stress-induced increase in IL-1β in both brain areas, while IL-18 only in the hippocampus. Moreover, tianeptine administration diminished the increase in CCR2 levels in both brain areas, while in the hippocampus, tianeptine, along with venlafaxine CCL2 and iNOS levels. Next, we observed that in the hippocampus, tianeptine and fluoxetine suppressed upregulation of TLR4. Furthermore, venlafaxine suppressed NFкB p65-subunit phosphorylation, while fluoxetine enhanced the IкB level. Importantly, in the hippocampus, all antidepressants normalized evoked by stress changes in caspase-1 level, while tianeptine and venlafaxine also affect the levels of ASC and NLRP3 subunits. Our results provide new evidence that chronic administration of antidepressants exerts anti-inflammatory effects more pronounced in the hippocampus, through suppression of the NLRP3 inflammasome activation. These effects are accompanied by an improvement in the behavioral dysfunctions evoked by prenatal stress.

Prophylactic Effects of Bifidobacterium adolescentis on Anxiety and Depression-Like Phenotypes After Chronic Stress: A Role of the Gut Microbiota-Inflammation Axis

Stress disturbs the balance of the gut microbiota and stimulates inflammation-to-brain mechanisms. Moreover, stress leads to anxiety and depressive disorders. Bifidobacterium adolescentis displays distinct anti-inflammatory effects. However, no report has focused on the anxiolytic and antidepressant effects of B. adolescentis related to the gut microbiome and the inflammation on chronic restraint stress (CRS) in mice. We found that pretreatment with B. adolescentis increased the time spent in the center of the open field apparatus, increased the percentage of entries into the open arms of the elevated plus-maze (EPM) and the percentage of time spent in the open arms of the EPM, and decreased the immobility duration in the tail suspension test as well as the forced swimming test (FST). Moreover, B. adolescentis increased the sequence proportion of Lactobacillus and reduced the sequence proportion of Bacteroides in feces. Furthermore, B. adolescentis markedly reduced the protein expression of interleukin-1β (IL-1β), tumor necrosis factor α (TNF-α), p-nuclear factor-kappa B (NF-κB) p65 and Iba1 and elevated brain derived neurotrophic factor (BDNF) expression in the hippocampus. We conclude that the anxiolytic and antidepressant effects of B. adolescentis are related to reducing inflammatory cytokines and rebalancing the gut microbiota.

NPY Receptor 2 Mediates NPY Antidepressant Effect in the mPFC of LPS Rat by Suppressing NLRP3 Signaling Pathway

Accumulated evidences show that neuroinflammation play a pivotal role in the pathogenesis of depression. Neuropeptide Y (NPY) and its receptors have been demonstrated to have anti-inflammative as well as antidepressant effects. In the present study, the ability of NPY to modulate depressive-like behaviors induced by lipopolysaccharides (LPS) in rats and the receptors and signaling mechanisms involved were investigated. Continuous injection LPS (i.p) for 4 days led to development of depressive-like behaviors in rats, accompanied with M1-type microglia activation and increased levels of IL-1β as well as decreased levels of NPY and Y2R expression in the mPFC selectively. Local injection of NPY into the medial prefrontal cortex (mPFC) ameliorated the depression-like behaviors and suppressed the NLRP3 inflammasome signaling pathway. Y2R agonist PYY (3-36) mimicked and Y2R antagonist BIIE0246 abolished the NPY effects in the mPFC. All these results suggest that NPY and Y2R in the mPFC are involved in the pathophysiology of depression and NPY plays an antidepressant role in the mPFC mainly via Y2R, which suppresses the NLRP3 signaling pathway, in LPS-induced depression model rats.