Neuroinflammation: The Pathogenic Mechanism of Neurological Disorders

Auraptene-ameliorating depressive-like behaviors induced by lipopolysaccharide combined with chronic unpredictable mild stress in mice mitigate hippocampal neuroinflammation mediated by microglia

An inflammatory response is one of the pathogeneses of depression. The anti-inflammatory and neuroprotective effects of auraptene have previously been confirmed. We established an inflammatory depression model by lipopolysaccharide (LPS) injection combined with unpredictable chronic mild stress (uCMS), aiming to explore the effects of auraptene on depressive-like behaviors in adult mice. Mice were divided into a control group, vehicle group, fluoxetine group, celecoxib group, and auraptene group. Then, behavioral tests were conducted to evaluate the effectiveness of auraptene in ameliorating depressive-like behavior. Cyclooxygenase-2 (COX-2), C-reactive protein (CRP), tumor necrosis factor (TNF-α), interleukin-6 (IL-6), and interleukin-1β (IL-1β) were examined by ELISA. Interleukin-10 (IL-10), interleukin-4 (IL-4), and transforming growth factor-β (TGF-β) were examined by protein chip technology. The morphology of microglia was observed by the immunohistochemical method. The data showed that, compared with the control group, the vehicle group mice exhibited a depressive-like behavioral phenotype, accompanied by an imbalance in inflammatory cytokines and the activation of microglia in the hippocampus. The depressive behaviors of the auraptene group's mice were significantly alleviated, along with the decrease in pro-inflammatory factors and increase in anti-inflammatory factors, while the activation of microglia was inhibited in the hippocampus. Subsequently, we investigated the role of auraptene in vitro-cultured BV-2 cells treated with LPS. The analysis showed that auraptene downregulated the expression of IL-6, TNF-α, and NO, and diminished the ratio of CD86/CD206. The results showed that auraptene reduced the excessive phagocytosis and ROS production of LPS-induced BV2 cells. In conclusion, auraptene relieved depressive-like behaviors in mice probably via modulating hippocampal neuroinflammation mediated by microglia.

Synergistic action of vitamin D3 and A on motor activity regulation in mice model of extrapyramidal syndrome: Correlational insights into astrocyte regulation, cytokine modulation, and dopaminergic activity

BACKGROUND

Extrapyramidal syndromes (EPS) represent neurological side effects of antipsychotic medications, characterized by motor disturbances. While previous studies have indicated the neuroprotective effects of vitamin D and A against EPS, the underlying mechanisms of this protection remain unclear.

METHODS

Twenty-four adult mice were categorized into four groups: positive and negative control groups, one receiving a dopamine antagonist, and the other receiving both a dopamine antagonist and vitamins D and A. Sections of the corticobasal loop, specifically the motor cortex (M1) and basal nuclei (CPu), were prepared for Immunohistochemistry (IHC) and stained with Glial Fibrillary Acidic Protein (GFAP) to visualize reactive astrocytes. ELISA assays for TNF-α, IL-6, IL-4, IL-13, and dopamine levels were performed on homogenized brain sections.

RESULTS

The EPS group exhibited a significant increase in TNF-α and IL-6 levels in M1 and CPu. Treatment with dopamine agonists and vitamin D&A resulted in significant reductions in IL-6 levels. Only the Vitamin D&A group showed a significant decline in TNF-α. The EPS group recorded significant decreases in IL-4 and IL-13, with IL-13 significantly elevated in the dopamine agonist and Vitamin D&A groups. IL-4 was notably increased in the Vitamin D&A groups. Dopamine concentration significantly declined in the EPS group, with improvements observed in the groups treated with dopamine agonists, and vitamin D&A. Reactive astrocytes were significantly expressed in the M1 and CPu of the EPS group but poorly expressed in other groups.

CONCLUSIONS

EPS is linked to astrocyte activation, an upsurge in pro-inflammatory cytokines, a decline in anti-inflammatory cytokines, and dopamine in the corticobasal loop. Administration of vitamin D3 and A was found to suppres pro-inflammatory cytokines and repress anti-inflammatory cytokines associated with astrocyte activation.

Imaging neuroinflammation in individuals with substance use disorders

Increasing evidence suggests a role of neuroinflammation in substance use disorders (SUDs). This Review presents findings from neuroimaging studies assessing brain markers of inflammation in vivo in individuals with SUDs. Most studies investigated the translocator protein 18 kDa (TSPO) using PET; neuroimmune markers myo-inositol, choline-containing compounds, and N-acetyl aspartate using magnetic resonance spectroscopy; and fractional anisotropy using MRI. Study findings have contributed to a greater understanding of neuroimmune function in the pathophysiology of SUDs, including its temporal dynamics (i.e., acute versus chronic substance use) and new targets for SUD treatment.

MoS2 2D materials induce spinal cord neuroinflammation and neurotoxicity affecting locomotor performance in zebrafish

MoS2 nanosheets belong to an emerging family of nanomaterials named bidimensional transition metal dichalcogenides (2D TMDCs). The use of such promising materials, featuring outstanding chemical and physical properties, is expected to increase in several fields of science and technology, with an enhanced risk of environmental dispersion and associated wildlife and human exposures. In this framework, the assessment of MoS2 nanosheets toxicity is instrumental to safe industrial developments. Currently, the impact of the nanomaterial on the nervous tissue is unexplored. In this work, we use as in vivo experimental model the early-stage zebrafish, to investigate whether mechano-chemically exfoliated MoS2 nanosheets reach and affect, when added in the behavioral ambient, the nervous system. By high throughput screening of zebrafish larvae locomotor behavioral changes upon exposure to MoS2 nanosheets and whole organism live imaging of spinal neuronal and glial cell calcium activity, we report that sub-acute and prolonged ambient exposures to MoS2 nanosheets elicit locomotor abnormalities, dependent on dose and observation time. While 25 μg mL-1 concentration treatments exerted transient effects, 50 μg mL-1 ones induced long-lasting changes, correlated to neuroinflammation-driven alterations in the spinal cord, such as astrogliosis, glial intracellular calcium dysregulation, neuronal hyperactivity and motor axons retraction. By combining integrated technological approaches to zebrafish, we described that MoS2 2D nanomaterials can reach, upon water (i.e. ambient) exposure, the nervous system of larvae, resulting in a direct neurological damage.

The role of neuroinflammation in neurodegenerative diseases: current understanding and future therapeutic targets

Neuroinflammation refers to a highly complicated reaction of the central nervous system (CNS) to certain stimuli such as trauma, infection, and neurodegenerative diseases. This is a cellular immune response whereby glial cells are activated, inflammatory mediators are liberated and reactive oxygen and nitrogen species are synthesized. Neuroinflammation is a key process that helps protect the brain from pathogens, but inappropriate, or protracted inflammation yields pathological states such as Parkinson's disease, Alzheimer's, Multiple Sclerosis, and other neurodegenerative disorders that showcase various pathways of neurodegeneration distributed in various parts of the CNS. This review reveals the major neuroinflammatory signaling pathways associated with neurodegeneration. Additionally, it explores promising therapeutic avenues, such as stem cell therapy, genetic intervention, and nanoparticles, aiming to regulate neuroinflammation and potentially impede or decelerate the advancement of these conditions. A comprehensive understanding of the intricate connection between neuroinflammation and these diseases is pivotal for the development of future treatment strategies that can alleviate the burden imposed by these devastating disorders.

Platelet Dynamics in Neurodegenerative Disorders: Investigating the Role of Platelets in Neurological Pathology

Background: Neurological disorders, particularly those associated with aging, pose significant challenges in early diagnosis and treatment. The identification of specific biomarkers, such as platelets (PLTs), has emerged as a promising strategy for early detection and intervention in neurological health. This systematic review aims to explore the intricate relationship between PLT dynamics and neurological health, focusing on their potential role in cognitive functions and the pathogenesis of cognitive disorders. Methods: Adhering to PRISMA guidelines, a comprehensive search strategy was employed in the PubMed and Scholar databases to identify studies on the role of PLTs in neurological disorders published from 2013 to 2023. The search criteria included studies focusing on PLTs as biomarkers in neurological disorders, their dynamics, and their potential in monitoring disease progression and therapy effectiveness. Results: The systematic review included 104 studies, revealing PLTs as crucial biomarkers in neurocognitive disorders, acting as inflammatory mediators. The findings suggest that PLTs share common features with altered neurons, which could be utilised for monitoring disease progression and evaluating the effectiveness of treatments. PLTs are identified as significant biomarkers for detecting neurological disorders in their early stages and understanding the pathological events leading to neuronal death. Conclusions: The systematic review underscores the critical role of PLTs in neurological disorders, highlighting their potential as biomarkers for the early detection and monitoring of disease progression. However, it also emphasises the need for further research to solidify the use of PLTs in neurological disorders, aiming to enhance early diagnosis and intervention strategies.

Advancements in Single-Cell RNA Sequencing Research for Neurological Diseases

Neurological diseases are a major cause of the global burden of disease. Although the mechanisms of the occurrence and development of neurological diseases are not fully clear, most of them are associated with cells mediating neuroinflammation. Yet medications and other therapeutic options to improve treatment are still very limited. Single-cell RNA sequencing (scRNA-seq), as a delightfully potent breakthrough technology, not only identifies various cell types and response states but also uncovers cell-specific gene expression changes, gene regulatory networks, intercellular communication, and cellular movement trajectories, among others, in different cell types. In this review, we describe the technology of scRNA-seq in detail and discuss and summarize the application of scRNA-seq in exploring neurological diseases, elaborating the corresponding specific mechanisms of the diseases as well as providing a reliable basis for new therapeutic approaches. Finally, we affirm that scRNA-seq promotes the development of the neuroscience field and enables us to have a deeper cellular understanding of neurological diseases in the future, which provides strong support for the treatment of neurological diseases and the improvement of patients' prognosis.

P2X7 receptors: a bibliometric review from 2002 to 2023

For many years, there has been ongoing research on the P2X7 receptor (P2X7R). A comprehensive, systematic, and objective evaluation of the scientific output and status of P2X7R will be instrumental in guiding future research directions. This study aims to present the status and trends of P2X7R research from 2002 to 2023. Publications related to P2X7R were retrieved from the Web of Science Core Collection database. Quantitative analysis and visualization tools were Microsoft Excel, VOSviewer, and CiteSpace software. The analysis content included publication trends, literature co-citation, and keywords. 3282 records were included in total, with the majority of papers published within the last 10 years. Based on literature co-citation and keyword analysis, neuroinflammation, neuropathic pain, gastrointestinal diseases, tumor microenvironment, rheumatoid arthritis, age-related macular degeneration, and P2X7R antagonists were considered to be the hotspots and frontiers of P2X7R research. Researchers will get a more intuitive understanding of the status and trends of P2X7R research from this study.

Polystyrene Nano- and Microplastic Particles Induce an Inflammatory Gene Expression Profile in Rat Neural Stem Cell-Derived Astrocytes In Vitro

Microplastics are considered an emerging environmental pollutant due to their ubiquitous presence in the environment. However, the potential impact of microplastics on human health warrants further research. Recent studies have reported neurobehavioral and neurotoxic effects in marine and rodent models; however, their impact on the underlying cellular physiology in mammals remains unclear. Herein, we exposed neural stem cells and neural stem cell-derived astrocytes, oligodendrocytes, and neurons to various sizes and concentrations of polystyrene nano- and microplastics. We investigated their cellular uptake, impact on cytotoxicity, and alteration of gene expression through transcriptome profiling. The cell type most affected by decreased viability were astrocytes after 7 days of repeated exposure. Transcriptional analysis showed that 1274 genes were differentially expressed in astrocytes exposed to 500 nm microplastics, but only 531 genes were altered in astrocytes exposed to 50 nm nanoplastics. Both canonical pathway and Kyoto Encyclopedia of Genes and Genomes analysis showed that upregulated pathways were involved in neuroinflammation, innate and adaptive immunity, cell migration, proliferation, extracellular matrix remodeling, and cytoskeleton structures. The downregulated pathways were involved in lipid metabolism, specifically fatty acid oxidation and cholesterol metabolism. Our results show that neural stem cell-derived astrocytes repeatedly exposed to nano- and microplastics for 7 days undergo changes that are hallmarks of astrogliosis.

Neuroinflammation and acquired traumatic CNS injury: a mini review

Acquired traumatic central nervous system (CNS) injuries, including traumatic brain injury (TBI) and spinal cord injury (SCI), are devastating conditions with limited treatment options. Neuroinflammation plays a pivotal role in secondary damage, making it a prime target for therapeutic intervention. Emerging therapeutic strategies are designed to modulate the inflammatory response, ultimately promoting neuroprotection and neuroregeneration. The use of anti-inflammatory agents has yielded limited support in improving outcomes in patients, creating a critical need to re-envision novel approaches to both quell deleterious inflammatory processes and upend the progressive cycle of neurotoxic inflammation. This demands a comprehensive exploration of individual, age, and sex differences, including the use of advanced imaging techniques, multi-omic profiling, and the expansion of translational studies from rodents to humans. Moreover, a holistic approach that combines pharmacological intervention with multidisciplinary neurorehabilitation is crucial and must include both acute and long-term care for the physical, cognitive, and emotional aspects of recovery. Ongoing research into neuroinflammatory biomarkers could revolutionize our ability to predict, diagnose, and monitor the inflammatory response in real time, allowing for timely adjustments in treatment regimens and facilitating a more precise evaluation of therapeutic efficacy. The management of neuroinflammation in acquired traumatic CNS injuries necessitates a paradigm shift in our approach that includes combining multiple therapeutic modalities and fostering a more comprehensive understanding of the intricate neuroinflammatory processes at play.

IL-1β disrupts blood-brain barrier development by inhibiting endothelial Wnt/β-catenin signaling

During neuroinflammation, the proinflammatory cytokine Interleukin-1β (IL-1β) impacts blood-brain barrier (BBB) function by disrupting brain endothelial tight junctions, promoting vascular permeability, and increasing transmigration of immune cells. Here, we examined the effects of Il-1β on the in vivo development of the BBB. We generated a doxycycline-inducible transgenic zebrafish model that drives secretion of Il-1β in the CNS. To validate the utility of our model, we showed Il-1β dose-dependent mortality, recruitment of neutrophils, and expansion of microglia. Using live imaging, we discovered that Il-1β causes a significant reduction in CNS angiogenesis and barriergenesis. To demonstrate specificity, we rescued the Il-1β induced phenotypes by targeting the zebrafish il1r1 gene using CRISPR/Cas9. Mechanistically, we determined that Il-1β disrupts BBB development by decreasing Wnt/β-catenin transcriptional activation in brain endothelial cells. Given that several neurodevelopmental disorders are associated with inflammation, our findings support further investigation into the connections between proinflammatory cytokines, neuroinflammation, and neurovascular development.

Lipids in Psychiatric Disorders: Functional and Potential Diagnostic Role as Blood Biomarkers

Lipids are a crucial component of the human brain, serving important structural and functional roles. They are involved in cell function, myelination of neuronal projections, neurotransmission, neural plasticity, energy metabolism, and neuroinflammation. Despite their significance, the role of lipids in the development of mental disorders has not been well understood. This review focused on the potential use of lipids as blood biomarkers for common mental illnesses, such as major depressive disorder, anxiety disorders, bipolar disorder, and schizophrenia. This review also discussed the impact of commonly used psychiatric medications, such as neuroleptics and antidepressants, on lipid metabolism. The obtained data suggested that lipid biomarkers could be useful for diagnosing psychiatric diseases, but further research is needed to better understand the associations between blood lipids and mental disorders and to identify specific biomarker combinations for each disease.

Microglia-derived TNF-α contributes to RVLM neuronal mitochondrial dysfunction via blocking the AMPK-Sirt3 pathway in stress-induced hypertension

BACKGROUND

Neuroinflammation in the rostral ventrolateral medulla (RVLM) has been associated with the pathogenesis of stress-induced hypertension (SIH). Neuronal mitochondrial dysfunction is involved in many pathological and physiological processes. However, the impact of neuroinflammation on neuronal mitochondrial homeostasis and the involved signaling pathway in the RVLM during SIH are largely unknown.

METHODS

The morphology and phenotype of microglia and the neuronal mitochondrial injury in vivo were analyzed by immunofluorescence, Western blot, RT-qPCR, transmission electron microscopy, and kit detection. The underlying mechanisms of microglia-derived tumor necrosis factor-α (TNF-α) on neuronal mitochondrial function were investigated through in vitro and in vivo experiments such as immunofluorescence and Western blot. The effect of TNF-α on blood pressure (BP) regulation was determined in vivo via intra-RVLM microinjection of TNF-α receptor antagonist R7050.

RESULTS

The results demonstrated that BP, heart rate (HR), renal sympathetic nerve activity (RSNA), plasma norepinephrine (NE), and electroencephalogram (EEG) power increased in SIH rats. Furthermore, the branching complexity of microglia in the RVLM of SIH rats decreased and polarized into M1 phenotype, accompanied by upregulation of TNF-α. Increased neuronal mitochondria injury was observed in the RVLM of SIH rats. Mechanistically, Sirtuin 3 (Sirt3) and p-AMPK expression were markedly downregulated in both SIH rats and TNF-α-treated N2a cells. AMPK activator A769662 upregulated AMPK-Sirt3 signaling pathway and consequently reversed TNF-α-induced mitochondrial dysfunction. Microinjection of TNF-α receptor antagonist R7050 into the RVLM of SIH rats significantly inhibited the biological activities of TNF-α, increased p-AMPK and Sirt3 levels, and alleviated neuronal mitochondrial injury, thereby reducing c-FOS expression, RSNA, plasma NE, and BP.

CONCLUSIONS

This study revealed that microglia-derived TNF-α in the RVLM impairs neuronal mitochondrial function in SIH possibly through inhibiting the AMPK-Sirt3 pathway. Therefore, microglia-derived TNF-α in the RVLM may be a possible therapeutic target for the intervention of SIH.

Beneficial effects of natural flavonoids on neuroinflammation

Neuroinflammation is the fundamental immune response against multiple factors in the central nervous system and is characterized by the production of inflammatory mediators, activated microglia and astrocytes, and the recruitment of innate and adaptive immune cells to inflammatory sites, that contributes to the pathological process of related brain diseases, such as Alzheimer’s disease, Parkinson’s disease, depression, and stroke. Flavonoids, as a species of important natural compounds, have been widely revealed to alleviate neuroinflammation by inhibiting the production of pro-inflammatory mediators, elevating the secretion of anti-inflammatory factors, and modulating the polarization of microglia and astrocyte, mainly via suppressing the activation of NLRP3 inflammasome, as well as NF-κB, MAPK, and JAK/STAT pathways, promoting Nrf2, AMPK, BDNF/CREB, Wnt/β-Catenin, PI3k/Akt signals and SIRT1-mediated HMGB1 deacetylation. This review will provide the latest and comprehensive knowledge on the therapeutic benefits and mechanisms of natural flavonoids in neuroinflammation, and the natural flavonoids might be developed into food supplements or lead compounds for neuroinflammation-associated brain disorders.