Interleukin-18 from neurons and microglia mediates depressive behaviors in mice with post-stroke depression

Innate lymphoid cells in the brain: Focus on ischemic stroke

The innate immune system consists of a diverse set of immune cells, including innate lymphoid cells (ILCs), which are grouped into subsets based on their transcription factors and cytokine profiles. Among these are natural killer (NK) cells, group 1 ILCs, group 2 ILCs, group 3 ILCs, and lymphoid tissue inducers (LTi). Unlike T and B cells, ILCs do not express the diverse antigen receptors typically found on those cells. Although ILCs function in various systems, further research is needed to understand their role in the brain and their involvement in neurological diseases such as stroke. This review explores the general immunological aspects of ILCs, with a particular focus on their role in the central nervous system and the pathophysiology of ischemic stroke.

Therapeutic effects of exercise on depression: The role of microglia

Major depressive disorderadversely affects mental health. Traditional therapeutic approaches, including medication, psychological intervention, and physical therapy, exert beneficial effects on depression. However, these approaches are associated with some limitations, such as high cost, adverse reactions, recurrent episodes, and low patient adherence. Previous studies have demonstrated that exercise therapy can effectively mitigate depressive symptoms, although the underlying mechanism has not been elucidated. Recent studies have suggested that depression is a microglial disease. Microglia regulate the inflammatory response, synaptic plasticity, neurogenesis, kynurenine pathway and the activation of hypothalamic-pituitary-adrenal axis, all of which affect depression. Exercise therapy is reported to shift the balance of microglial M1/M2 polarization in the hippocampus, frontal lobe, and striatum, suppressing the release of pro-inflammatory factors and consequently alleviating behavioral deficits in animal models of depression. Further studies are needed to examine the specific effects of different exercise regimens on microglia to identify the exercise regimen with the best therapeutic effect.

Association between atherogenic index of plasma and post-stroke depression: a cross-sectional study

Background: Few studies have established a link between the atherogenic index of plasma (AIP) and post-stroke depression (PSD). This study aims to further investigate the potential relationship between the AIP and PSD, and to provide references for the prevention and prognosis management of patients with PSD.Methods: A cross-sectional study was conducted using data from participants in the National Health and Nutrition Examination Survey from 2005 to 2018. Inclusion criteria required complete data on the AIP, stroke history, and depression status. Weighted logistic regression models and restricted cubic splines (RCS) were employed to examine the association between the AIP and PSD. By subgroup and interaction analyses, the stability associated with AIP and PSD was assessed between different subgroups.Results: Among the 32,364 participants ultimately enrolled in the study, 482 were diagnosed with PSD. In the weighted multivariate logistic regression adjustment model 3, AIP, as a continuous variable, was positively associated with the risk of PSD [odds ratio (OR) = 1.85, 95% confidence interval (CI): 1.18, 2.91; P = 0.007]. After the quartile classification of AIP, the adjusted model 3 showed that the risk of PSD in group Q4 was significantly higher than that in group Q1 (OR = 1.61, 95%CI:1.10, 2.34; P = 0.006). In the RCS linearity test, AIP was positively associated with the risk of PSD (Pnon-linear = 0.357). The interaction test demonstrated that AIP only had an interaction with gender (Pinteraction = 0.031) and not with other variables (Pinteraction > 0.05).Conclusion: AIP was positively associated with the prevalence of PSD, suggesting that AIP may be a promising predictor of the risk of developing PSD. In addition, the interaction of AIP and gender differences combined to influence the incidence of PSD.

Interleukin-18 interacts with NKCC1 to mediate brain injury after intracerebral hemorrhage

Interleukin 18 (IL-18), a proinflammatory cytokine, has been implicated in various neurological disorders, including cerebrovascular disease and psychiatric disorders. In a previous study, IL-18 was observed to activate microglia and enhance the inflammatory response following intracranial hemorrhage (ICH). However, the underlying mechanism remains unclear. In the present study, we found that IL-18 and IL-18 receptor (IL-18 R) are primarily secreted by neurons during the early stages after ICH, with microglia becoming the predominant source at 12-24 h after ICH. Meanwhile, the expression level of IL-18 R increased following ICH, along with an augmentation in the binding affinity of IL-18 R to IL-18. Subsequently, the deficiency of IL-18 R mitigated neurological impairment and subsequent activation of inflammatory pathways in mice post-ICH. Moreover, our findings suggest that IL-18-induced neurological injury after ICH may be mediated by the interaction between IL18R and NKCC1. Significantly, the NKCC1 inhibitor rescued the neurologic injury after ICH. In conclusion, our study suggests that targeting the IL-18/IL-18R/NKCC1 pathway could be an effective therapeutic strategy to attenuate secondary brain injury after ICH.

Expression pattern of long non-coding RNAs in treatment-naïve and medicated schizophrenia patients

Schizophrenia is a disabling mental disorder that affects 1% of people over their lifetime. The etiology and mechanism of schizophrenia are very complex, and many genes are involved in many different signaling pathways in the etiology of this disease. According to recent studies, one of the important mechanisms altered in this disorder is the regulation of immune system and the inflammation mechanism. In the present study, we evaluated the peripheral blood expression pattern of four lncRNAs and three protein-coding genes in the treatment- naïve patients, and medicated patients compared with sex and age-matched controls. In the medicated-patients, expression levels of IFNG, IL18RAP, AC007278.2 were significantly up-regulated (P < 0.05); and the expression level of IFNG-AS1-001 was significantly down-regulated compared to healthy controls (P < 0.05). However, levels of IL18R1, AC007278.3 and IFNG-AS1-003 were not different between these groups. In the treatment-naïve patients, IFNG, IL18R1, IL18RAP, IFNG-AS1-001, AC007278.2, and AC007278.3 were significantly up-regulated compared to controls. On the other hand, IFNG-AS1-003 was significantly down-regulated in the treatment-naïve patients compared to controls. Based on the Spearman correlation matrix, there was a significant correlation between genes in the treatment-naïve patients. We also showed the high sensitivity and specificity of IFNG-AS1-003, IFNG, IL18R1, and AC007278.3 in the identification of treatment-naïve patients from controls. The current study contributes further evidence to the understanding of the role of lncRNAs in the pathogenesis of schizophrenia. Future research is necessary to establish the validity of lncRNAs as peripheral markers for this condition.

Association between non-high-density lipoprotein cholesterol to high-density lipoprotein cholesterol ratio (NHHR) and the risk of post-stroke depression: A cross-sectional study

BACKGROUND

Limited observational research has explored the relationship between the non-high-density lipoprotein cholesterol (non-HDL-C) to high-density lipoprotein cholesterol (HDL-C) ratio (NHHR) and the risk of post-stroke depression (PSD). This study aims to investigate the potential associations between NHHR and PSD.

METHODS

A cross-sectional study was conducted using data from stroke participants aged 20 and older, sourced from the National Health and Nutrition Examination Survey (NHANES) spanning 2005 to 2018. Depression was assessed using the PHQ-9 questionnaire. The association between NHHR and PSD risk was evaluated through weighted multivariate logistic regression and restricted cubic spline (RCS) models. Subgroup and sensitivity analyses were performed to validate the findings.

RESULTS

In the continuous model, the NHHR value for the PSD group (3.23±1.84) was significantly higher than that of the non-PSD group (2.79±1.40, p=0.015). Logistic regression analysis in the fully adjusted model revealed a positive association between NHHR and PSD (OR 1.16, 95 % CI 1.03-1.30, p=0.016). Interaction tests showed no significant differences across strata (p > 0.05 for interaction). Restricted cubic spline results indicated a linear dose-response relationship between NHHR and PSD risk (P for non-linearity = 0.6). This association persisted in various subgroup analyses.

CONCLUSION

NHHR was significantly correlated with an increased risk of PSD among U.S. adults. Further re-search on NHHR could contribute to the prevention and treatment of PSD.

Genetic association and drug target exploration of inflammation-related proteins with risk of major depressive disorder

BACKGROUND

In numerous observational studies, circulating inflammation-related proteins have been linked with major depressive disorder (MDD), yet the precise causal direction of this relationship remains unclear. This study aims to investigate the potential causal link between inflammation-related proteins and the risk of developing MDD.

METHODS

We utilized summary data from a genome-wide association study (GWAS) of 91 circulating inflammation-associated proteins in 14,824 individuals of European descent. Additionally, we incorporated findings from a substantial GWAS on MDD, which included 294,322 cases and 741,438 controls. Our analysis employed a two-sample bidirectional Mendelian randomization (MR) approach, with inverse variance weighting (IVW) as the primary method. We augmented this with two supplementary techniques (MR-Egger and weighted median approaches) to detect and address potential pleiotropy. Furthermore, to identify and evaluate possible drug targets, we conducted a thorough search within the Drug-Gene Interaction Database (DGIdb).

RESULTS

Analysis using MR unveiled significant and causative associations between genetically determined CASP-8 (odds ratio (OR): 0.97), CD40 (OR: 0.96), IL-18 (OR: 0.98), SLAMF1 (OR: 0.97), and uPA (OR: 0.98) with MDD. Conversely, reverse MR analysis indicated causal associations between MDD and CCL19 (OR: 1.15), HGF (OR: 1.15), IL-8 (OR: 1.10), IL-18 (OR: 1.11), IL20RA (OR: 1.12), TGFA (OR: 1.12) and TNFSF14 (OR: 1.16). Notably, a significant bidirectional causal link was observed between IL-18 and MDD. Gene-drug analysis identified CD40, HGF, IL-8, IL-18, SLAMF1, and TGFA as potential therapeutic targets.

CONCLUSIONS

We've pinpointed causal links between inflammation-related proteins and MDD, offering compelling and innovative evidence to enhance our understanding of the inflammatory mechanisms involved in MDD and to investigate potential targets for anti-MDD medications.

Facile engineered macrophages-derived exosomes-functionalized PLGA nanocarrier for targeted delivery of dual drug formulation against neuroinflammation by modulation of microglial polarization in a post-stroke depression rat model

Post-stroke depression (POSD) is a common difficulty and most predominant emotional syndrome after stroke often consequences in poor outcomes. In the present investigation, we have designed and studied the neurologically active celastrol/minocycline encapsulated with macrophages-derived exosomes functionalized PLGA nanoformulations (CMC-EXPL) to achieve enhanced anti-inflammatory behaviour and anti-depressant like activity in a Rat model of POSD. The animal model of POSD was established through stimulating process with chronic unpredictable mild stress (CUM) stimulations after procedure of middle cerebral artery occlusion (MCAO). Neuronal functions and Anti-inflammation behaviours were observed by histopathological (H&E) examination and Elisa analyses, respectively. The anti-depressive activity of the nanoformulations treated Rat models were evaluated by open-field and sucrose preference test methods. Microglial polarization was evaluated via flow-cytometry and qRT-PCR observations. The observed results exhibited that prepared nanoformulations reduced the POSD-stimulated depressive-like activities in rat models as well alleviated the neuronal damages and inflammatory responses in the cerebral hippocampus. Importantly, prepared CMC-EXPL nanoformulation effectively prevented the M1 pro-inflammatory polarization and indorsed M2 anti-inflammatory polarization, which indicates iNOS and CD86 levels significantly decreased and upsurged Arg-1 and CD206 levels. CMC-EXPL nanoformulation suggestively augmented anti-depressive activities and functional capability and also alleviated brain inflammation in POSD rats, demonstrating its therapeutic potential for POSD therapy.

Advancing Post-Stroke Depression Research: Insights from Murine Models and Behavioral Analyses

Post-stroke depression (PSD) represents a significant neuropsychiatric complication that affects between 39% and 52% of stroke survivors, leading to impaired recovery, decreased quality of life, and increased mortality. This comprehensive review synthesizes our current knowledge of PSD, encompassing its epidemiology, risk factors, underlying neurochemical mechanisms, and the existing tools for preclinical investigation, including animal models and behavioral analyses. Despite the high prevalence and severe impact of PSD, challenges persist in accurately modeling its complex symptomatology in preclinical settings, underscoring the need for robust and valid animal models to better understand and treat PSD. This review also highlights the multidimensional nature of PSD, where both biological and psychosocial factors interplay to influence its onset and course. Further, we examine the efficacy and limitations of the current animal models in mimicking the human PSD condition, along with behavioral tests used to evaluate depressive-like behaviors in rodents. This review also sets a new precedent by integrating the latest findings across multidisciplinary studies, thereby offering a unique and comprehensive perspective of existing knowledge. Finally, the development of more sophisticated models that closely replicate the clinical features of PSD is crucial in order to advance translational research and facilitate the discovery of future effective therapies.

Advances in biosensors for major depressive disorder diagnostic biomarkers

Depression is one of the most common mental disorders and is mainly characterized by low mood or lack of interest and pleasure. It can be accompanied by varying degrees of cognitive and behavioral changes and may lead to suicide risk in severe cases. Due to the subjectivity of diagnostic methods and the complexity of patients' conditions, the diagnosis of major depressive disorder (MDD) has always been a difficult problem in psychiatry. With the discovery of more diagnostic biomarkers associated with MDD in recent years, especially emerging non-coding RNAs (ncRNAs), it is possible to quantify the condition of patients with mental illness based on biomarker levels. Point-of-care biosensors have emerged due to their advantages of convenient sampling, rapid detection, miniaturization, and portability. After summarizing the pathogenesis of MDD, representative biomarkers, including proteins, hormones, and RNAs, are discussed. Furthermore, we analyzed recent advances in biosensors for detecting various types of biomarkers of MDD, highlighting representative electrochemical sensors. Future trends in terms of new biomarkers, new sample processing methods, and new detection modalities are expected to provide a complete reference for psychiatrists and biomedical engineers.

The impact of cytokines in neuroinflammation-mediated stroke

Cerebral stroke is ranked as the third most common contributor to global mortality and disability. The involvement of inflammatory mechanisms, both peripherally and within the CNS, holds significance in the pathophysiological cascades following the initiation of stroke. After the onset of acute stroke, predominantly ischemic, a subsequent phase of neuroinflammation ensues. It is a dual-effect process that not only exacerbates injury, leading to cell death, but paradoxically, it also serves a shielding role in facilitating recovery. Cytokines serve as pivotal mediators within the inflammatory cascade, actively contributing to the progression of ischemic damage. Stroke is followed by increased expression of pro-inflammatory cytokines including TNF-α, IL-1β, IL-6, etc. leading to the recruitment and stimulation of glial cells and peripheral leukocytes at the site of injury, promoting neuroinflammation. Cytokines can directly induce neuronal injury and death through various mechanisms, including excitotoxicity, oxidative stress, HPA-axis activation, secretion of matrix metalloproteinase and apoptosis. They can also amplify the inflammatory response, leading to further neuronal damage. Therapeutic strategies aimed at modulating cytokine release, immune response and cytokine signalling or activity are being explored as potential interventions to mitigate neuroinflammation and its detrimental effects in stroke. In this review, we have given a concise summary of our current knowledge of the function of various cytokines, brain inflammation and various signalling and molecular pathways including JAK/STAT3, TGF-β/Smad, MAPK, HMGB1/TLR and NF-κB modulated cytokines regulation in stroke. Therapeutic agents such as MCC950, genistein, edaravone, minocycline, etc. targeting various cytokines-associated signalling pathways have shown efficacy in preclinical and clinical trials reducing the pathophysiology of the illness were also addressed in this study.

Gut microbiota is necessary for pair-housing to protect against post-stroke depression in mice

The goal of this study is to investigate the role of microbiota-gut-brain axis involved in the protective effect of pair-housing on post-stroke depression (PSD). PSD model was induced by occluding the middle cerebral artery (MCAO) plus restraint stress for four weeks. At three days after MCAO, the mice were restrained 2 h per day. For pair-housing (PH), each mouse was pair housed with a healthy isosexual cohabitor for four weeks. While in the other PH group, their drinking water was replaced with antibiotic water. On day 35 to day 40, anxiety- and depression-like behaviors (sucrose consumption, open field test, forced swim test, and tail-suspension test) were conducted. Results showed pair-housed mice had better performance on anxiety- and depression-like behaviors than the PSD mice, and the richness and diversity of intestinal flora were also improved. However, drinking antibiotic water reversed the effects of pair-housing. Furthermore, pair-housing had an obvious improvement in gut barrier disorder and inflammation caused by PSD. Particularly, they showed significant decreases in CD8 lymphocytes and mRNA levels of pro-inflammatory cytokines (TNF-a, IL-1β and IL-6), while IL-10 mRNA was upregulated. In addition, pair-housing significantly reduced activated microglia and increased Nissl's body in the hippocampus of PSD mice. However, all these improvements were worse in the pair-housed mice administrated with antibiotic water. We conclude that pair-housing significantly improves PSD in association with enhanced functions of microbiota-gut-brain axis, and homeostasis of gut microbiota is indispensable for the protective effect of pair-housing on PSD.

A novel approach to treating post-stroke depression: administration of Botulinum Toxin A via local facial injection

Background

Post-stroke depression (PSD) is a frequent complication following a stroke, characterized by prolonged feelings of sadness and loss of interest, which can significantly impede stroke rehabilitation, increase disability, and raise mortality rates. Traditional antidepressants often have significant side effects and poor patient adherence, necessitating the exploration of more suitable treatments for PSD. Previous researchers and our research team have discovered that Botulinum Toxin A (BoNT-A) exhibits antidepressant effects. Therefore, our objective was to assess the efficacy and side effects of BoNT-A treatment in patients with PSD.

Methods

A total of 71 stroke patients meeting the inclusion criteria were allocated to the two group. 2 cases were excluded due to severe neurological dysfunction that prevented cooperation and 4 cases were lost follow-up. Ultimately, number of participants in the BoNT-A group (n = 32) and Sertraline group (n = 33). Treatment efficacy was evaluated 1, 2, 4, 8 and 12 weeks post-treatment.

Results

There were no significant differences in baseline characteristics between the two groups (p > 0.05). Both groups exhibited comparable treatment efficacy, with fewer side effects observed in the BoNT-A group compared to the Sertraline group. BoNT-A therapy demonstrated significant effects as early as the first week (p < 0.05), and by the 12th week, there was a notable decrease in neuropsychological scores, significantly lower than the baseline level. The analysis revealed significant differences in measurements of the Hamilton Depression Scale (HAMD) (F(770) = 12.547, p = 0.000), Hamilton Anxiety Scale (HAMA) (F(951) = 10.422, p = 0.000), Self-Rating Depression Scale (SDS) (F(1385) = 10.607, p = 0.000), and Self-Rating Anxiety Scale (SAS) (F(1482) = 11.491, p = 0.000).

Conclusion

BoNT-A treatment effectively reduces depression symptoms in patients with PSD on a continuous basis.

Repurposing Ketamine in the Therapy of Depression and Depression-Related Disorders: Recent Advances and Future Potential

Depression represents a prevalent and enduring mental disorder of significant concern within the clinical domain. Extensive research indicates that depression is very complex, with many interconnected pathways involved. Most research related to depression focuses on monoamines, neurotrophic factors, the hypothalamic-pituitary-adrenal axis, tryptophan metabolism, energy metabolism, mitochondrial function, the gut-brain axis, glial cell-mediated inflammation, myelination, homeostasis, and brain neural networks. However, recently, Ketamine, an ionotropic N-methyl-D-aspartate (NMDA) receptor antagonist, has been discovered to have rapid antidepressant effects in patients, leading to novel and successful treatment approaches for mood disorders. This review aims to summarize the latest findings and insights into various signaling pathways and systems observed in depression patients and animal models, providing a more comprehensive view of the neurobiology of anxious-depressive-like behavior. Specifically, it highlights the key mechanisms of ketamine as a rapid-acting antidepressant, aiming to enhance the treatment of neuropsychiatric disorders. Moreover, we discuss the potential of ketamine as a prophylactic or therapeutic intervention for stress-related psychiatric disorders.

Efficacy and safety of acupuncture treatment for post-stroke depression: A protocol for systematic review and meta-analysis

BACKGROUND

Post-stroke depression is a common complication of stroke, with a high incidence rate and low recognition rate. Many patients do not receive effective intervention at the onset, which affects subsequent treatment outcomes. Post-stroke depression not only impacts the patient's mental well-being but also increases the risk of stroke recurrence and poor prognosis. Therefore, it has become a significant public health concern. Acupuncture has gained significant popularity in the treatment of post-stroke depression. However, there are inconsistent clinical research results regarding its efficacy and safety. This systematic review aims to gather and critically assess all available evidence regarding the effectiveness and safety of acupuncture in the treatment of post-stroke depression in patients.

METHODS

We will conduct thorough searches for relevant studies in multiple electronic databases (PubMed, Embase, Cochrane Library, China National Knowledge Infrastructure, VIP Database, Wan-fang Data and China Biomedical Database). Our search scope will encompass studies published from the inception of each database until September 2023. To evaluate the potential bias in all the included studies, we will adhere to the guidelines offered in the Cochrane Handbook. The total effective rate will be the primary outcome. To conduct a systematic review, we will employ RevMan 5.4 software.

RESULTS

This study will obtain efficacy and safety of acupuncture for the treatment of post-stroke depression.

CONCLUSIONS

The conclusions of this study will provide evidence-based perspectives that can guide clinical decision-making regarding the practicality and recommended timing of using acupuncture to treat post-stroke depression. Furthermore, this study will help advance the clinical application of acupuncture treatment for post-stroke depression and enhance its efficacy while ensuring patient safety.

Clinical application of repetitive transcranial magnetic stimulation in improving functional impairments post-stroke: review of the current evidence and potential challenges

In recent years, the stroke incidence has been increasing year by year, and the related sequelae after stroke, such as cognitive impairment, motor dysfunction, and post-stroke depression, seriously affect the patient's rehabilitation and daily activities. Repetitive transcranial magnetic stimulation (rTMS), as a safe, non-invasive, and effective new rehabilitation method, has been widely recognized in clinical practice. This article reviews the application and research progress of rTMS in treating different functional impairments (cognitive impairment, motor dysfunction, unilateral spatial neglect, depression) after stroke in recent years, and preliminary summarized the possible mechanisms. It has been found that the key parameters that determine the effectiveness of rTMS in improving post-stroke functional impairments include pulse number, stimulated brain areas, stimulation intensity and frequency, as well as duration. Generally, high-frequency stimulation is used to excite the ipsilateral cerebral cortex, while low-frequency stimulation is used to inhibit the contralateral cerebral cortex, thus achieving a balance of excitability between the two hemispheres. However, the specific mechanisms and the optimal stimulation mode for different functional impairments have not yet reached a consistent conclusion, and more research is needed to explore and clarify the best way to use rTMS. Furthermore, we will identify the issues and challenges in the current research, explore possible mechanisms to deepen understanding of rTMS, propose future research directions, and offer insightful insights for better clinical applications.

Neuroinflammation and Post-Stroke Depression: Focus on the Microglia and Astrocytes

Post-stroke depression (PSD), a frequent and disabling complication of stroke, has a strong impact on almost thirty percent of stroke survivors. The pathogenesis of PSD is not completely clear so far. Neuroinflammation following stroke is one of underlying mechanisms that involves in the pathophysiology of PSD and plays an important function in the development of depression and is regarded as a sign of depression. During the neuroinflammation after ischemic stroke onset, both astrocytes and microglia undergo a series of morphological and functional changes and play pro-inflammatory or anti-inflammatory effect in the pathological process of stroke. Importantly, astrocytes and microglia exert dual roles in the pathological process of PSD due to the phenotypic transformation. We summarize the latest evidence of neuroinflammation involving in PSD in this review, focus on the phenotypic transformation of microglia and astrocytes following ischemic stroke and reveal the dual roles of both microglia and astrocytes in the PSD via modulating the neuroinflammation.

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

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

Mechanisms associated with post-stroke depression and pharmacologic therapy

Stroke is one of the most common cerebrovascular diseases, which is the cause of long-term mental illness and physical disability, Post-stroke depression (PSD) is the most common neuropsychiatric complication after stroke, and its mechanisms are characterized by complexity, plurality, and diversity, which seriously affects the quality of survival and prognosis of patients. Studies have focused on and recognized neurotransmitter-based mechanisms and selective serotonin-reuptake inhibitors (SSRIs) can be used to treat PSD. Neuroinflammation, neuroendocrinology, neurotrophic factors, and the site of the stroke lesion may affect neurotransmitters. Thus the mechanisms of PSD have been increasingly studied. Pharmacological treatment mainly includes SSRIs, noradrenergic and specific serotonergic antidepressant (NaSSA), anti-inflammatory drugs, vitamin D, ect, which have been confirmed to have better efficacy by clinical studies. Currently, there is an increasing number of studies related to the mechanisms of PSD. However, the mechanisms and pharmacologic treatment of PSD is still unclear. In the future, in-depth research on the mechanisms and treatment of PSD is needed to provide a reference for the prevention and treatment of clinical PSD.

Association of non-HDL-C and depression: a cross-sectional analysis of the NHANES data

Objectives

Non-high-density lipoprotein cholesterol (non-HDL-C) has attracted attention because it is associated with a variety of diseases and is easy to measure. However, the relationship between non-HDL-C and depression is still unclear. Our aim was to assess the relationship between non-HDL-C and depression using the cross-sectional NHANES survey from 2005 to 2018.

Methods

We examined the association between non-HDL-C and depression using weighted multivariable logistic regression models and subgroup analysis. Sensitivity analysis demonstrated the robustness of the results.

Results

There were 42,143 participants in this study and 8.6% had depression (weighted 7.53%). Non-HDL-C was higher in participants with depression compared to those without depression (weighted mean 3.64 vs. 3.73, p < 0.01). There was a positive association between non-HDL-C and depression with a 95% OR of 1.22 adjusted for multifactorial (95% CI,1.03-1.45). In subgroup analyses, non-HDL-C was positively associated with depression in men (OR, 1.31; 95% CI, 1.01-1.70), normal BMI (OR: 0.93; 95% CI: 0.66-1.32) and in participants without hypertension (OR, 1.29; 95% CI, 1.01-1.66).

Conclusion

Non-HDL-C positively correlated with depression, and further research may be better for clinical service.

Functional and structural brain reorganization in patients with ischemic stroke: a multimodality MRI fusion study

Understanding how structural and functional reorganization occurs is crucial for stroke diagnosis and prognosis. Previous magnetic resonance imaging (MRI) studies focused on the analyses of a single modality and demonstrated abnormalities in both lesion regions and their associated distal regions. However, the relationships of multimodality alterations and their associations with poststroke motor deficits are still unclear. In this study, 71 hemiplegia patients and 41 matched healthy controls (HCs) were recruited and underwent MRI examination at baseline and at 2-week follow-up sessions. A multimodal fusion approach (multimodal canonical correlation analysis + joint independent component analysis), with amplitude of low-frequency fluctuation (ALFF) and gray matter volume (GMV) as features, was used to extract the co-altered patterns of brain structure and function. Then compared the changes in patients' brain structure and function between baseline and follow-up sessions. Compared with HCs, the brain structure and function of stroke patients decreased synchronously in the local lesions and their associated distal regions. Damage to structure and function in the local lesion regions was associated with motor function. After 2 weeks, ALFF in the local lesion regions was increased, while GMV did not improve. Taken together, the brain structure and function in the local lesions and their associated distal regions were damaged synchronously after ischemic stroke, while during motor recovery, the 2 modalities were changed separately.

Catapol reduced the cognitive and mood dysfunctions in post-stroke depression mice via promoting PI3K-mediated adult neurogenesis

Adult hippocampal neurogenesis provides a regenerative resource for neural tissue and enhances neural plasticity, which is beneficial for brain functional rehabilitation post stroke. Recently, an increasing number of metabolic drugs have been reported to attenuate behavioral symptoms in neurodegeneration or psychiatric disorders via promoting adult hippocampal neurogenesis. Bioeffects of catapol show its potential as an antidiabetic though it has been previously widely indicated to perform the neuroprotective functions. However, the systematic evidence to support the behavioral effects of catapol to PSD model and what is the role of adult neurogenesis in such effects remains unexplored. In current study, we created the PSD model by combining MCAO procedure and CORT feeding. The treatment of catapol strikingly reduced the depressive/anxiety behavior in PSD model. Moreover, treatment of catapol also improved the cognitive functions. Immunofluorescence indicates that catapol could promote adult hippocampal neurogenesis in PSD model, and TMZ treatment further confirmed the role of the hippocampal neurogenesis in catapol's therapeutic effects to PSD. Cultural neurons also indicates that PI3K is the key signal in regulating catapol mediated neurogenesis. By administrating the PI3K specific inhibitor, we found that PI3K is the key to mediate the behavioral effects of catapol to PSD. In conclusion, catapol could perform as the effective drug to treat PSD via the PI3K mediated adult hippocampal neurogenesis.

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.

The Central Nervous System Source Modulates Microglia Function and Morphology In Vitro

The regional heterogeneity of microglia was first described a century ago by Pio del Rio Hortega. Currently, new information on microglia heterogeneity throughout central nervous system (CNS) regions is being revealed by high-throughput techniques. It remains unclear whether these spatial specificities translate into different microglial behaviors in vitro. We cultured microglia isolated from the cortex and spinal cord and analyzed the effect of the CNS spatial source on behavior in vitro by applying the same experimental protocol and culture conditions. We analyzed the microglial cell numbers, function, and morphology and found a distinctive in vitro phenotype. We found that microglia were present in higher numbers in the spinal-cord-derived glial cultures, presenting different expressions of inflammatory genes and a lower phagocytosis rate under basal conditions or after activation with LPS and IFN-γ. Morphologically, the cortical microglial cells were more complex and presented longer ramifications, which were also observed in vivo in CX3CR1^+/GFP transgenic reporter mice. Collectively, our data demonstrated that microglial behavior in vitro is defined according to specific spatial characteristics acquired by the tissue. Thus, our study highlights the importance of microglia as a source of CNS for in vitro studies.

CRS induces depression-like behavior after MCAO in rats possibly by activating p38 MAPK

Post-stroke depression (PSD) is a common neuropsychiatric complication of stroke, which seriously affects the quality of life and prognosis of patients. Nevertheless, the pathogenesis of PSD remains unclear. In our study, a PSD rat model was established by chronic restraint stress (CRS) combined with middle cerebral artery occlusion (MCAO). Depressive and anxiety-like behaviors were tested, as well as Neuronal loss and Apoptosis. The expression of synapse and p38 MAPK signaling pathway -relevant proteins was detected. Our data indicated that CRS combined with MCAO could induce depression-like and anxiety-like behaviors, which led to neuronal damage, apoptosis, and cellular loss in the left parietal cortex and left hippocampus. Furthermore, CRS combined with MCAO decreased synaptic plasticity in the parietal cortex and left hippocampus. We found that CRS combined with MCAO had activated the p38 MAPK signaling pathway, and decreased the expression of pathway-related proteins MKK6 and MKK3. These results suggested that CRS combined with MCAO could lead to depression-like behavior via neuronal damage, apoptosis and reduced synaptic plasticity, which might be related to the activation of the p38 MAPK pathway. Therefore, it provides novel ideas for the research on the intervention and prevention mechanisms of PSD.

Subanesthetic dose of S-ketamine improved cognitive dysfunction via the inhibition of hippocampal astrocytosis in a mouse model of post-stroke chronic stress

Post-stroke chronic stress (PSCS) is generally associated with the poorer recovery and more pronounced cognitive dysfunction. Recent evidence has implied that S-ketamine can reduce suicidal ideation in treatment-resistant depression. In this current study, we aimed to investigate whether the administration of S-ketamine ameliorated cognitive deficits under PSCS conditions, which was established by a model combining middle cerebral artery occlusion (MCAO) and chronic restraint stress. Our data suggested that mice exposed to PSCS exhibited depression-like behavior and cognitive impairment, which coincided with astrocytosis as indicated by increased GFAP-positive cells and impairment of long-time potentiation (LTP) in the hippocampal CA1. Subanesthetic doses (10 mg/kg) of S-ketamine have significantly mitigated depression-like behaviors, cognitive deficits and LTP impairment, reduced astrocytosis, excessive GABA, and inflammatory factors, including NLRP3 and IL-18 in astrocytes in the CA1. Besides, neuroprotective effects induced by S-ketamine administration were found in vitro but could be partially reversed by an agonist of the NLRP3 nigericin. Our current data also suggests that the subanesthetic doses of S-ketamine improved cognitive dysfunction via the inhibition of hippocampal astrocytosis in a mouse model of PSCS.

The NLRP3 inflammasome in depression: Potential mechanisms and therapies

Increasing evidence suggests that the failure of clinical antidepressants may be related with neuroinflammation. The NOD-, LRR- and pyrin domain-containing protein 3 (NLRP3) inflammasome is an intracellular multiprotein complex, and has been considered as a key contributor to the development of neuroinflammation. Inhibition of NLRP3 inflammasome is an effective method for depression treatment. In this review, we summarized current researches highlighting the role of NLRP3 inflammasome in the pathology of depression. Firstly, we discussed NLRP3 inflammasome activation in patients with depression and animal models. Secondly, we outlined the possible mechanisms driving the activation of NLRP3 inflammasome. Thirdly, we discussed the pathogenetic role of NLRP3 inflammasome in depression. Finally, we overviewed the current and potential antidepressants targeting the NLRP3 inflammasome. Overall, the inhibition of NLRP3 inflammasome activation may be a potential therapeutic strategy for inflammation-related depression.

Acute stress induces severe neural inflammation and overactivation of glucocorticoid signaling in interleukin-18-deficient mice

Interleukin-18 (IL18) is an inflammatory cytokine that is related to psychiatric disorders such as depression and cognitive impairment. We previously found that IL18 deficiency may cause hippocampal impairment, resulting in depression-like behavioral changes. However, the potential role of IL18 in stressful conditions remains uncertain. In the present study, we examined the effect of IL18 on neural inflammation and stress tolerance during acute stress. Littermate Il18^+/+ and Il18^-/- mice were exposed to a single restraint stress for 6 h, and all assessments were performed 18 h after the mice were released from the restraint. In Il18^-/- mice exposed to acute stress, the immobility times in both the forced swim test and tail suspension test were decreased, although no difference was observed in Il18^+/+ mice. Il1β, Il6, and Tnfα expression levels in the hippocampus of stressed Il18^-/- mice were significantly higher than those in the other groups. Moreover, the numbers of astrocytes and microglia, including those in the active form, were also increased compared with those in other groups. Regarding the molecular mechanism, the HSF5 and TTR genes were specifically expressed in stressed Il18^-/- mice. As a potential treatment, intracerebral administration of IL18 to Il18^-/- mice resulted in partial recovery of changes in behavioral assessments. Our results revealed that IL18-deficient mice were more sensitive and had a longer response to acute stress than that in normal mice. In addition, neural inflammation and augmentation of glucocorticoid signals caused by stress were more intense and remained longer in Il18^-/- mice, resulting in behavioral changes. In conclusion, IL18 might be an indispensable factor that modulates the stress response and maintains balance between neural inflammation and glucocorticoid signaling.

Microglia Involves in the Immune Inflammatory Response of Poststroke Depression: A Review of Evidence

Poststroke depression (PSD) does not exist before and occurs after the stroke. PSD can appear shortly after the onset of stroke or be observed in the weeks and months after the acute or subacute phase of stroke. The pathogenesis of PSD is unclear, resulting in poor treatment effects. With research advancement, immunoactive cells in the central nervous system, particularly microglia, play a role in the occurrence and development of PSD. Microglia affects the homeostasis of the central nervous system through various factors, leading to the occurrence of depression. The research progress of microglia in PSD has been summarized to review the evidence regarding the pathogenesis and treatment target of PSD in the future.

Oridonin relieves depressive-like behaviors by inhibiting neuroinflammation and autophagy impairment in rats subjected to chronic unpredictable mild stress

Major depressive disorder (MDD) is a severe life-threatening disorder with increasing prevalence. However, the mechanistic interplay between depression, neuroinflammation, and autophagy is yet to be demonstrated. This study investigated the effect of Oridonin on CUMS-induced depression, neuroinflammation, and autophagy impairment. Male 4-week-old Sprague-Dawley rats were subjected to chronic unpredictable mild stress (CUMS), some of which were injected with Oridonin, fluoxetine (FLX), or their combination at different durations of CUMS. CUMS significantly increased the levels of cytokines (IL-1β, IL-18, and caspase-1), reduced autophagy-related protein levels (Beclin-1, p62, Atg5, and LC3B), and caused microglia cells activation. Oridonin prevented and reversed the depressive-like behavior. Furthermore, it has a stronger and longer-lasting antidepressant effect than FLX. And the antidepressant effect of Oridonin in combination with fluoxetine was greater than that of high-dose fluoxetine alone. In addition, Oridonin significantly normalized autophagy-related protein levels, and reduced levels of cytokines by blocking the interaction between NLRP3 and NEK7. Similarly, Oridonin abolished levels of cytokines and reversed autophagy impairment in LPS-activated BV2 cells. All these results supported our hypothesis that Oridonin possesses potent anti-depressive action, which might be mediated via inhibition of neuroinflammation and autophagy impairment by blocking the interaction between NLRP3 and NEK7.

Interleukin-18 mediated inflammatory brain injury after intracerebral hemorrhage in male mice

Interleukin-18 (IL-18), a pro-inflammatory cytokine, is thought to be associated with inflammation in many neurological diseases such as ischemic stroke and poststroke depression, but the role of IL-18 in inflammatory injury after intracerebral hemorrhage (ICH) remains unclear. In this study, we established the ICH model in male mice and found that IL-18 expression including protein and mRNA levels was significantly increased in brain tissues after ICH. Meanwhile, exogenous IL-18 exacerbated cerebral hematoma and neurological deficits following ICH. In the IL-18 knockout group, the size of hematoma and neurological functions after ICH was decreased compared with the wild-type group, suggesting the critical role of IL-18 on the modulation of brain injury after ICH. Importantly, exogenous IL-18 increased microglial activation in brain tissues after ICH. Furthermore, IL-18 knockout resulted in the reduction of activated microglia after ICH. These results indicated that IL-18 may regulate the inflammatory response after ICH through the activation of microglia. Thus, IL-18 is expected to be a promising therapeutic target for secondary brain injury after ICH.

Alleviative effects of foraging exercise on depressive-like behaviors in chronic mild stress-induced ischemic rat model

BACKGROUND

Poststroke depression (PSD) is a common complication that seriously affects the functional recovery and prognosis of an individual. As some patients with PSD fail to respond to drug therapy, it is urgent to find a viable alternative treatment.

METHODS

An active exercise program known as foraging exercise (FE), using food as bait, was designed. First, focal ischemia and chronic unpredictable mild stress (CUMS) were used to establish a PSD model in rats. FE was then performed for 4 weeks. Body weight and behavioral assessments were conducted at the end of the 4^th and 8^th weeks.

RESULTS

After 8 weeks, the results revealed that, compared with the PSD group, the behavioral scores of the rats in the PSD/FE group were significantly improved, the expression of Iba-1 in the affected frontal lobe and striatum was decreased, and serum levels of IL-6 and the IL-6/IL-10 ratio were downregulated. However, the ratio of residual brain volume in rats that had experienced CUMS was significantly less than that in the stroke group.

CONCLUSION

FE can alleviate the behavioral scores of PSD rats, and its mechanism may be related to a modulation of the immune-inflammation response of microglia. Furthermore, chronic, persistent stress may increase the volume of cerebral infarction after stroke.

Differential expression analysis of microRNAs and mRNAs in the mouse hippocampus of post-stroke depression (PSD) based on transcriptome sequencing

To clarify the differential expressions of microRNAs and mRNAs in a PSD model, this study employed PSD mice for model construction by injecting vasoconstrictor ET-1 (angioendothelin-1) into the medial prefrontal cortex (mPFC) of mice. The animals underwent elevated plus maze test, open field test, tail suspension test, and forced swimming test subsequently. Transcriptome sequencing was performed to analyze the differentially expressed mRNAs and microRNAs. The results showed that open arm entries and time of PSD mice were markedly decreased. Times of the entry to center for mice in the model group were apparently decreased. The climbing time of mice in the model group was greatly decreased. The behavior of PSD mice indicated a marked change, and several indicators of the behavioral tests were significantly lower than those of the control group. Transcriptome sequencing analysis demonstrated that expressions of 1 206 genes and 21 microRNAs were markedly upregulated in model group, whereas expressions of 2 113 genes and 32 microRNAs were markedly downregulated. GO analysis revealed that the differentially expressed genes were mainly involved in regulatory pathways of single-multicellular organism process, developmental process, cell periphery, plasma membrane, and neuron projection. Meanwhile, KEGG analysis results indicated that the differentially expressed genes mostly participated in signaling pathways of neuroactive ligand-receptor interaction, calcium signaling pathway, and cytokine-cytokine receptor interaction. In conclusion, differentially expressed microRNAs and mRNAs were screened, which offers a theoretical foundation for further investigation of molecular mechanisms and novel insight for the early identification, prevention, and treatment of PSD.

Interleukins and Ischemic Stroke

Ischemic stroke after cerebral artery occlusion is one of the major causes of chronic disability worldwide. Interleukins (ILs) play a bidirectional role in ischemic stroke through information transmission, activation and regulation of immune cells, mediating the activation, multiplication and differentiation of T and B cells and in the inflammatory reaction. Crosstalk between different ILs in different immune cells also impact the outcome of ischemic stroke. This overview is aimed to roughly discuss the multiple roles of ILs after ischemic stroke. The roles of IL-1, IL-2, IL-4, IL-5, IL-6, IL-8, IL-9, IL-10, IL-12, IL-13, IL-15, IL-16, IL-17, IL-18, IL-19, IL-21, IL-22, IL-23, IL-32, IL-33, IL-34, IL-37, and IL-38 in ischemic stroke were discussed in this review.

Shugan Jieyu Capsule in Post-Stroke Depression Treatment: From Molecules to Systems

Post-stroke depression (PSD) is the most common non-cognitive neuropsychiatric complication after stroke, and about a third of patients with stroke have depression. Although a great deal of effort has been made to treat PSD, the efficacy thereof has not been satisfactory, due to the complex pathological mechanism underlying PSD. In Traditional Chinese Medicine (TCM) theory, PSD is considered to be a combination of “stroke” and “Yu Zheng.” The holistic, multi-drug, and multi-objective nature of TCM is consistent with the treatment concept of systems medicine for PSD. TCM has a very long history of being used to treat depression, and various TCM prescriptions have been clinically proven to be effective in improving depression. Among the numerous prescriptions for treating depression, Shugan Jieyu capsule (SG) is one of the classic prescriptions. Additionally, clinical studies have increasingly confirmed that using SG alone or in combination with Western medicine can significantly improve the psychiatric symptoms of PSD patients. Here, we reviewed the mechanism of antidepressant action of SG and its targets in PSD pathologic systems. This review provides further insights into the pharmacological mechanism, drug interaction, and clinical application of TCM prescriptions, as well as a basis for the development of new drugs to treat PSD.

Elevated Red Blood Cell Distribution Width Levels at Admission Predicts Depression After Acute Ischemic Stroke: A 3-Month Follow-Up Study

PURPOSE

Red blood cell distribution width (RDW) is closely related to inflammatory-related disease markers. The present study aimed to investigate the association between the red blood cell distribution width (RDW) and post-stroke depression (PSD).

PATIENTS AND METHODS

A total of 414 patients with acute ischemic stroke (AIS) admitted to our hospital from June 2018 to July 2021 were consecutively enrolled and received 3 months' follow-up. According to the 17-item Hamilton Depression Scale (HAMD) assessment, they were divided into PSD group and non-PSD group. Diagnosis of PSD was made in accordance with DSM-IV. RDW was recorded within 24 hours of admission.

RESULTS

Among the included 414 patients, 95 (22.95%) patients were diagnosed as having PSD at 3 months after stroke. The results showed significantly higher level of RDW in patients with depression (13.69 (IQR13.24-13.88) vs. 13.56 (IQR 12.67-13.77), P<0.001) at admission than patients without depression. After adjustment for potential confounding factors, the odds ratio of PSD was 5.707 (95% CI, 2.717-11.989) for the highest tertile of RDW compared with the lowest tertile. Moreover, based on the receiver operating characteristic (ROC) curve, the optimal cutoff of RDW levels as an indicator for the prediction of PSD was projected as 13.01, which yielded a sensitivity of 83% and a specificity of 41.0%, with an area under the curve (AUC) of 0.643 (95% CI, 0.585-0.701; P = 0.012).

CONCLUSION

Higher RDW levels at admission were found to be correlated with PSD 3 months after stroke.

Elevated monocyte-to-HDL cholesterol ratio predicts post-stroke depression

OBJECTIVES

Inflammation plays an important role in the development of depression after stroke. Monocyte-to-HDL Cholesterol Ratio (MHR) recently emerged as a novel comprehensive inflammatory indicator in recent years. This study aimed to investigate whether there is a relationship between MHR levels and post-stroke depression (PSD).

METHODS

From February 2019 to September 2021, patients with acute ischemic stroke (AIS) were recruited within 7 days post-stroke from the two centers and blood samples were collected after admission. The 17-item Hamilton Depression Scale (HAMD-17) was used to measure depressive symptoms at 3 months after stroke. Patients were given the DSM-V criteria for diagnosis of PSD.

RESULTS

Of the 411 enrolled patients, 92 (22.38%) patients were diagnosed with PSD at 3-months follow-up. The results also showed significantly higher level of MHR in patients with depression [0.81 (IQR 0.67-0.87) vs. 0.61 (IQR 0.44-0.82), P < 0.001] at admission than patients without depression. Multivariate logistic regression revealed that MHR (OR 6.568, 95% CI: 2.123-14.565, P = 0.015) was an independent risk factor for the depression at 3 months after stroke. After adjustment for potential confounding factors, the odds ratio of PSD was 5.018 (95% CI: 1.694-14.867, P = 0.004) for the highest tertile of MHR compared with the lowest tertile. Based on the ROC curve, the optimal cut-off value of MHR as an indicator for prediction of PSD was projected to be 0.55, which yielded a sensitivity of 87% and a specificity of 68.3%, with the area under the curve at 0.660 (95% CI: 0.683-0.781; P = 0.003).

CONCLUSION

Elevated level of MHR was associated with PSD at 3 months, suggesting that MHR might be a useful Inflammatory markers to predict depression after stroke.

Exposure to X-rays Causes Depression-like Behaviors in Mice via HMGB1-mediated Pyroptosis

The widespread application of ionizing radiation in industrial and medical fields leads to the increased brain exposure to X-rays. Radiation brain injury (RBI) seriously affects health of patients by causing cognitive dysfunction and neuroinflammation. However, the link between X-ray exposure and depressive symptoms and their detailed underlying mechanisms have not been well studied. Herein, we investigated the potential depression-like behaviors in mice exposed to X-rays and then explored the role of HMGB1 in this injury. We found that X-ray stimulation induced the generation of reactive oxygen species (ROS) in the prefrontal cortex in a dose-dependent manner, leading to the occurrence of depression-like behaviors of the mice. Moreover, X-ray exposure increased the expression of HMGB1, activated NLRP3 inflammasome signaling pathway and microglial cells, and then facilitated the release of pro-inflammatory cytokines, resulting in the pyroptosis and neuron loss both in vivo and in vitro. Additionally, glycyrrhizin (Gly), which is a HMGB1 inhibitor, reversed X-ray-induced behavioral changes and neuronal damage. Our findings indicated that HMGB1-mediated pyroptosis was involved in radiation-induced depression.

Acupuncture inhibits NLRP3 inflammasome activation in the prefrontal cortex of a chronic stress rat model of depression

The Nod-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome-driven inflammatory response plays a key role in the pathophysiology of depression. Mounting evidence suggests that acupuncture is an effective treatment for depression. In this study, we investigated the effects of acupuncture treatment at the acupoints Baihui (GV20) and Yintang (GV29) on NLRP3 inflammasome in the prefrontal cortex (PFC) of an animal model of depression. Rats that underwent chronic unpredictable mild stress (CUMS) for 6 weeks showed depressive-like behaviors, which were confirmed by sucrose preference and locomotor activity in the open field test. The protein levels of NLRP3, apoptotic speck-containing protein with a card (ASC), and cysteinyl aspartate specific proteinase-1 (Caspase-1) in the PFC were detected by Western blot analysis. The mRNA and protein expressions of interleukin-1β (IL-1β) and interleukin-18 (IL-18) in the PFC were measured by the real-time polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. Our results showed that the depressive-like behaviors in stressed rats were reversed by acupuncture treatment. Compared with control rats, the protein expression of NLRP3, ASC, and Caspase-1 and the mRNA and protein expressions of IL-1β and IL-18 in the PFC were markedly increased in CUMS rats. Acupuncture treatment significantly decreased the levels of NLRP3 inflammasome components and inflammatory cytokines in the PFC. Acupuncture treatment also reduced the number of TUNEL-positive cells in the PFC. These results suggested that acupuncture has antidepressant-like effects, and its mechanism appears to be involved in the inhibition of NLRP3 inflammasome activation and apoptosis in the PFC.

Pharmacological tools to target NKCC1 in brain disorders

The chloride importer NKCC1 and the chloride exporter KCC2 are key regulators of neuronal chloride concentration. A defective NKCC1/KCC2 expression ratio is associated with several brain disorders. Preclinical/clinical studies have shown that NKCC1 inhibition by the United States FDA-approved diuretic bumetanide is a potential therapeutic strategy in preclinical/clinical studies of multiple neurological conditions. However, bumetanide has poor brain penetration and causes unwanted diuresis by inhibiting NKCC2 in the kidney. To overcome these issues, a growing number of studies have reported more brain-penetrating and/or selective bumetanide prodrugs, analogs, and new molecular entities. Here, we review the evidence for NKCC1 pharmacological inhibition as an effective strategy to manage neurological disorders. We also discuss the advantages and limitations of bumetanide repurposing and the benefits and risks of new NKCC1 inhibitors as therapeutic agents for brain disorders.

The role of microglia in chronic pain and depression: innocent bystander or culprit?

Clinical evidence shows that chronic pain and depression often accompany each other, but the underlying pathogenesis of comorbid chronic pain and depression remains mostly undetermined. Biotechnology is gradually revealing the phenotype and function of microglia, with great progress regarding microglia's role in neurodegeneration, depression, chronic pain, and other conditions. This article summarizes the role of microglia in chronic pain, depression, and comorbidities, which is conducive to finding new targets to treat chronic pain and depression.

Inhibition of the NKCC1/NF-κB Signaling Pathway Decreases Inflammation and Improves Brain Edema and Nerve Cell Apoptosis in an SBI Rat Model

Surgical brain injury (SBI) triggers microglia to release numerous inflammatory factors, leading to brain edema and neurological dysfunction. Reducing neuroinflammation and protecting the blood-brain barrier (BBB) are key factors to improve the neurological function and prognosis after SBI. Na⁺-K⁺-Cl^– cotransporter 1 (NKCC1) and nuclear factor κB (NF-κB) have been implicated in the secretion of inflammatory cytokines by microglia in brain injury. This study aimed to establish the role of NKCC1 in inducing inflammation in SBI, as well as to determine whether NKCC1 controls the release of interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) via phosphorylation of NF-κB in microglia, thus affecting BBB permeability and neuronal cell apoptosis. Male Sprague-Dawley (SD) rats were used to establish an SBI model. This study revealed that compared with the sham group, the expression levels of p-NKCC1, p-p65-NF-κB, and related inflammatory factor proteins in SBI model group significantly increased. After p-NKCC1 was inhibited, p-p65-NF-κB, IL-6, IL-1β, and TNF-α were downregulated, and nerve cell apoptosis and BBB permeability were significantly reduced. These findings suggest that the SBI-induced increase in p-NKCC1 exacerbates neuroinflammation, brain edema, and nerve function injury, which may be mediated by regulating the activity of p65-NF-κB that in turn influences the release of inflammatory factors.

The Role of Tet2-mediated Hydroxymethylation in Poststroke Depression

Poststroke depression (PSD) is a common complication of stroke and has long been a serious threat to human health. PSD greatly affects neurological recovery, quality of life and mortality. Recent studies have shown that 5-hydroxymethylcytosine (5hmC), an important epigenetic modification, is enriched in the brain and associated with many neurological diseases. However, its role in PSD is still unclear. In this study, middle cerebral artery occlusion (MCAO) and spatial restraint stress were used to successfully induce a PSD mouse model and resulted in reduced 5hmC levels, which were caused by Tet2. Furthermore, genome-wide analysis of 5hmC revealed that differentially hydroxymethylated regions (DhMRs) were associated with PSD. DhMRs were enriched among genes involved in the Wnt signaling pathway, neuron development and learning or memory. In particular,DhMRs were strongly enriched in genes with lymphoid enhancer factor 1 (LEF1) binding motifs. Finally, we demonstrated that decreases in TET2 expression in the brain caused PSD by decreasing Wnt/β-catenin/LEF1 pathway signaling to promote inflammatory factor IL-18 expression. In conclusion, our data highlight the potential for 5hmC modification as a therapeutic target for PSD.

Targeting the WNK-SPAK/OSR1 Pathway and Cation-Chloride Cotransporters for the Therapy of Stroke

Stroke is one of the major culprits responsible for morbidity and mortality worldwide, and the currently available pharmacological strategies to combat this global disease are scanty. Cation-chloride cotransporters (CCCs) are expressed in several tissues (including neurons) and extensively contribute to the maintenance of numerous physiological functions including chloride homeostasis. Previous studies have implicated two CCCs, the Na+-K+-Cl- and K+-Cl- cotransporters (NKCCs and KCCs) in stroke episodes along with their upstream regulators, the with-no-lysine kinase (WNKs) family and STE20/SPS1-related proline/alanine rich kinase (SPAK) or oxidative stress response kinase (OSR1) via a signaling pathway. As the WNK-SPAK/OSR1 pathway reciprocally regulates NKCC and KCC, a growing body of evidence implicates over-activation and altered expression of NKCC1 in stroke pathology whilst stimulation of KCC3 during and even after a stroke event is neuroprotective. Both inhibition of NKCC1 and activation of KCC3 exert neuroprotection through reduction in intracellular chloride levels and thus could be a novel therapeutic strategy. Hence, this review summarizes the current understanding of functional regulations of the CCCs implicated in stroke with particular focus on NKCC1, KCC3, and WNK-SPAK/OSR1 signaling and discusses the current and potential pharmacological treatments for stroke.

Ion channels and transporters in microglial function in physiology and brain diseases

Microglial cells interact with all components of the central nervous system (CNS) and are increasingly recognized to play essential roles during brain development, homeostasis and disease pathologies. Functions of microglia include maintaining tissue integrity, clearing cellular debris and dead neurons through the process of phagocytosis, and providing tissue repair by releasing anti-inflammatory cytokines and neurotrophic factors. Changes of microglial ionic homeostasis (Na⁺, Ca²⁺, K⁺, H⁺, Cl^-) are important for microglial activation, including proliferation, migration, cytokine release and reactive oxygen species production, etc. These are mediated by ion channels and ion transporters in microglial cells. Here, we review the current knowledge about the role of major microglial ion channels and transporters, including several types of Ca²⁺ channels (store-operated Ca²⁺ entry (SOCE) channels, transient receptor potential (TRP) channels and voltage-gated Ca²⁺ channels (VGCCs)) and Na⁺ channels (voltage-gated Na⁺ channels (Nav) and acid-sensing ion channels (ASICs)), K⁺ channels (inward rectifier K⁺ channels (K_ir), voltage-gated K⁺ channels (K_V) and calcium-activated K⁺ channels (K_Ca)), proton channels (voltage-gated proton channel (Hv1)), and Cl^- channels (volume (or swelling)-regulated Cl^- channels (VRCCs) and chloride intracellular channels (CLICs)). In addition, ion transporter proteins such as Na⁺/Ca²⁺ exchanger (NCX), Na⁺-K⁺-Cl^- cotransporter (NKCC1), and Na⁺/H⁺ exchanger (NHE1) are also involved in microglial function in physiology and brain diseases. We discussed microglial activation and neuroinflammation in relation to the ion channel/transporter stimulation under brain disease conditions and therapeutic aspects of targeting microglial ion channels/transporters for neurodegenerative disease, ischemic stroke, traumatic brain injury and neuropathic pain.

Neuroinflammation and fibrosis in stroke: The good, the bad and the ugly

Stroke is the leading cause of death and the main cause of disability in surviving patients. The detrimental interaction between immune cells, glial cells, and matrix components in stroke pathology results in persistent inflammation that progresses to fibrosis. A substantial effort is being directed toward understanding the exact neuroinflammatory events that take place as a result of stroke. The initiation of a potent cytokine response, along with immune cell activation and infiltration in the ischemic core, has massive acute deleterious effects, generally exacerbated by comorbid inflammatory conditions. There is secondary neuroinflammation that promotes further injury, resulting in cell death, but conversely plays a beneficial role, by promoting recovery. This highlights the need for a better understanding of the neuroinflammatory and fibrotic processes, as well as the need to identify new mechanisms and potential modulators. In this review, we summarize several aspects of stroke-induced inflammation, fibrosis, and include a discussion of cytokine inhibitors/inducers, immune cells, and fibro-inflammation signaling inhibitors in order to identify new pharmacological means of intervention.