New Target for Prevention and Treatment of Neuroinflammation: Microglia Iron Accumulation and Ferroptosis

Ferroptosis in the neurovascular unit after spinal cord injury

The mechanisms of secondary injury following spinal cord injury are complicated. The role of ferroptosis, which is a newly discovered form of regulated cell death in the neurovascular unit(NVU), is increasingly important. Ferroptosis inhibitors have been shown to improve neurovascular homeostasis and attenuate secondary spinal cord injury(SCI). This review focuses on the mechanisms of ferroptosis in NVU cells and NVU-targeted therapeutic strategies according to the stages of SCI, and analyzes possible future research directions.

Diosgenin ameliorating non-alcoholic fatty liver disease via Nrf2-mediated regulation of oxidative stress and ferroptosis

AIM

This study aimed to investigate the mechanisms through which diosgenin inhibits the pathogenesis of non-alcoholic fatty liver disease, focusing particularly on ferroptosis-related pathways and its reliance on nuclear factor erythroid 2-related factor 2.

MATERIALS AND METHODS

Using a rat model, we showed diosgenin's efficacy in reducing lipid deposition throughout the body and examined its impact on ferroptosis-related gene expression in vivo. Moreover, in vitro experiments using human hepatocellular liver carcinoma cell line cells were conducted to assess oxidative stress and ferroptosis levels.

RESULTS

Diosgenin decreased lipid accumulation and steatosis; lowered serum levels of total cholesterol, triglycerides, low-density lipoprotein cholesterol, glutamic pyruvic transaminase and glutamic oxaloacetic transaminase; reduced interleukin-1β and tumour necrosis factor-α; diosgenin decreased malondialdehyde levels; and increased serum superoxide dismutase levels in a rat model of high-fat diet-induced non-alcoholic fatty liver disease. Diosgenin upregulated the expression of nuclear factor erythroid 2-related factor 2 and its downstream ferroptosis-related genes to inhibit ferroptosis in the livers of rats with non-alcoholic fatty liver disease. Diosgenin decreased reactive oxygen species levels and enhanced the expression of ferroptosis-related genes in human hepatocellular liver carcinoma cells induced by free fatty acids, with its effects being dependent on nuclear factor erythroid 2-related factor 2.

CONCLUSIONS

This study highlights the potential of diosgenin from Dioscoreaceae plants in mitigating oxidative stress and ferroptosis levels through nuclear factor erythroid 2-related factor 2 regulation, offering novel insights into the treatment of non-alcoholic fatty liver disease and other metabolic disorders through traditional Chinese medicine.

Knockdown of microglial iron import gene, Slc11a2, worsens cognitive function and alters microglial transcriptional landscape in a sex-specific manner in the APP/PS1 model of Alzheimer's disease

BACKGROUND

Microglial cell iron load and inflammatory activation are significant hallmarks of late-stage Alzheimer's disease (AD). In vitro, microglia preferentially upregulate the iron importer, divalent metal transporter 1 (DMT1, gene name Slc11a2) in response to inflammatory stimuli, and excess iron can augment cellular inflammation, suggesting a feed-forward loop between iron import mechanisms and inflammatory signaling. However, it is not understood whether microglial iron import mechanisms directly contribute to inflammatory signaling and chronic disease in vivo. These studies determined the effects of microglial-specific knockdown of Slc11a2 on AD-related cognitive decline and microglial transcriptional phenotype.

METHODS

In vitro experiments and RT-qPCR were used to assess a role for DMT1 in amyloid-β-associated inflammation. To determine the effects of microglial Slc11a2 knockdown on AD-related phenotypes in vivo, triple-transgenic Cx3cr1Cre-ERT2;Slc11a2flfl;APP/PS1+or - mice were generated and administered corn oil or tamoxifen to induce knockdown at 5-6 months of age. Both sexes underwent behavioral analyses to assess cognition and memory (12-15 months of age). Hippocampal CD11b+ microglia were magnetically isolated from female mice (15-17 months) and bulk RNA-sequencing analysis was conducted.

RESULTS

DMT1 inhibition in vitro robustly decreased Aβ-induced inflammatory gene expression and cellular iron levels in conditions of excess iron. In vivo, Slc11a2KD APP/PS1 female, but not male, mice displayed a significant worsening of memory function in Morris water maze and a fear conditioning assay, along with significant hyperactivity compared to control WT and APP/PS1 mice. Hippocampal microglia from Slc11a2KD APP/PS1 females displayed significant increases in Enpp2, Ttr, and the iron-export gene, Slc40a1, compared to control APP/PS1 cells. Slc11a2KD cells from APP/PS1 females also exhibited decreased expression of markers associated with subsets of disease-associated microglia (DAMs), such as Apoe, Ctsb, Ly9, Csf1, and Hif1α.

CONCLUSIONS

This work suggests a sex-specific role for microglial iron import gene Slc11a2 in propagating behavioral and cognitive phenotypes in the APP/PS1 model of AD. These data also highlight an association between loss of a DAM-like phenotype in microglia and cognitive deficits in Slc11a2KD APP/PS1 female mice. Overall, this work illuminates an iron-related pathway in microglia that may serve a protective role during disease and offers insight into mechanisms behind disease-related sex differences.

Associations between quantitative susceptibility mapping with male obstructive sleep apnea clinical and imaging markers

PURPOSE

To quantitatively measure and compare whole-brain iron deposition between OSA patients and a healthy control group, we initially utilized QSM and evaluated its correlation with PSG results and cognitive function.

MATERIALS AND METHODS

A total of 28 OSA patients and 22 healthy control subjects matched in age, education level, and BMI were enrolled in our study. Each participant underwent scanning with 3D T1 and multi-echo GRE sequences. Additionally, PSG results were collected from OSA patients, and they underwent simple cognitive assessments. Finally, we analyzed the relationship between iron content in different brain regions, PSG results, and cognitive ability.

RESULTS

In OSA patients, iron content increased in the left temporal-pole-sup and right putamen, while it decreased in the left fusiform gyrus, left middle temporal gyrus, right inferior occipital gyrus, and right superior temporal gyrus. The correlation analysis between brain iron content and PSG results/cognitive scales is as follows: left fusiform gyrus and MMSE (r = -0.416, p = 0.028); right superior temporal gyrus and MMSE (r = 0.422, p = 0.025); left middle temporal gyrus and average oxygen saturation (r = -0.418, p = 0.027); left temporal-pole-sup and REM stage (rs = 0.466, p = 0.012); the right putamen and N1 stage (rs = 0.393. p = 0.039). Moreover, both MoCA (r = 0.598, p = 0.001) and MMSE (r = 0.456, p = 0.015) show a positive correlation with average oxygen saturation.

CONCLUSION

This study is the first to use QSM technology to show abnormal brain iron levels in OSA. Correlations between brain iron content, PSG, and cognition in OSA may reveal neuropathological mechanisms, aiding OSA diagnosis.

Matrine protects against experimental autoimmune encephalomyelitis through modulating microglial ferroptosis

Multiple sclerosis (MS) is an inflammatory demyelination neurodegenerative disease of the central nervous system (CNS). Ferroptosis has been implicated in a range of brain disorders, and iron-loaded microglia are frequently found in affected brain regions. However, the molecular mechanisms linking ferroptosis with MS have not been well-defined. The present study seeks to bridge this gap and investigate the impact of matrine (MAT), a herbal medicine with immunomodulatory capacities, on the regulation of oxidative stress and ferroptosis in the CNS of mice with experimental autoimmune encephalomyelitis (EAE), an animal model of MS. CNS of EAE mice contained elevated levels of ferroptosis-related molecules, e.g., MDA, LPCAT3 and PTGS2, but decreased expression of antioxidant molecules, including GSH and SOD, GPX4 and SLC7A11. This pathogenic process was reversed by MAT treatment, together with significant reduction of disease severity and CNS inflammatory demyelination. Furthermore, the expression of PTGS2 and LOX was largely increased in microglia of EAE mice, accompanied with increased production of IL-6 and TNF-α, indicating a proinflammatory phenotype of microglia that undergo oxidative stress/ferroptosis, and their expression was significantly reduced after MAT treatment. Together, our results indicate that ferroptosis/inflammation plays an important role in the pathogenesis of CNS autoimmunity, and inhibiting ferroptosis-induced microglial activation/inflammation could be a novel mechanism underlying the therapeutic effects of MAT on CNS inflammatory demyelination in EAE.

Iron deposition participates in LPS-induced cognitive impairment by promoting neuroinflammation and ferroptosis in mice

Neuroinflammation is a common pathological feature and onset in multiple cognitive disorders, including postoperative cognitive dysfunction (POCD). Iron deposition was proved to participate in this process. But how iron mediates inflammation-induced cognitive deficits remains unknown. This study aimed to investigate the mechanism of iron through the neuroprotective effect of the iron chelator deferoxamine (DFO) in a mouse model of lipopolysaccharide (LPS)-induced cognitive impairment. Adult C57BL/6 mice were pretreated with 0.5 μg of DFO three days before intracerebroventricular microinjection of 2 μg of LPS. The mice showed memory deficits by showing decreased percentage of distance and the time within the platform-site quadrant, fewer platform-site crossings, and shortened swimming distance around the platform in the Morris water maze test, which were significantly mitigated by DFO pretreatment. Mechanistically, DFO prevented LPS-induced iron accumulation and modulated the imbalance of proteins expression related to iron metabolism, including elevated transferrin (TF) levels and reduced ferritin (Fth) caused by LPS. DFO attenuated the LPS-induced lipid peroxidation and oxidative stress, which is evidenced by the decrease of malondialdehyde (MDA) and lipid peroxidation (LPO) levels and the increase of superoxide dismutase (SOD) activity and glutathione (GSH) concentration. Moreover, DFO ameliorated ferroptosis-like mitochondrial damages in the hippocampus and also alleviated the expression of ferroptosis-related proteins in the hippocampus. Additionally, DFO attenuated microglial activation, alleviated LPS-induced inflammation, and reduced elevated levels of IL-6 and TNF-α in the hippocampus. Taken together, our findings suggested that DFO exerts neuroprotective effects by alleviating excessive iron participation in lipid peroxidation, reducing the occurrence of ferroptosis, inhibiting the vicious cycle between oxidative stress and inflammation, and ultimately ameliorating LPS-induced cognitive dysfunction, providing novel insights into the immunopathogenesis of inflammation-related cognitive dysfunction and future potential prevention options targeting iron.

Amentoflavone attenuates homocysteine-induced neuronal ferroptosis-mediated inflammatory response: Involvement of the SLC7A11/GPX4 axis activation

Elevated homocysteine (Hcy) levels, referred to hyperhomocysteinemia, are associated with an increased risk of several neurological disorders. Ferroptosis and inflammation play a vital role in Hcy-induced neuronal dysfunction. Amentoflavone (AMF), an active natural biflavone compound, exhibits antioxidative, anti-inflammatory, and neuroprotective activities. This study aimed to explore the potential effects of AMF on Hcy-induced neuronal injury, with a particular focus on the underlying mechanisms involving ferroptosis and inflammation. We assessed neuronal damage in HT22 cells by measuring cell viability, lactate dehydrogenase (LDH) release, and proliferation rates. Additionally, we evaluated oxidative stress markers including the levels of reactive oxygen species (ROS), MitoSOX, mitochondrial membrane potential (MMP), malondialdehyde (MDA), and glutathione (GSH). Iron metabolism and ferroptosis-related gene expressions (Ptgs2, Tfr1, and Fth1) were quantified. TheSLC7A11/GPX4 axis was also detected. Our results showed that AMF treatment dramatically mitigated Hcy-induced neuronal injury by increasing cell viability, decreasing LDH release, and promoting cell proliferation. AMF treatment also reduced Hcy-induced oxidative stress and lipid peroxidation, as evidenced by reduced ROS, MitoSOX, MMP, and MDA levels, along with an increased GSH content in HT22 cells. In addition, AMF treatment reduced iron content and ferroptosis-related gene mRNA levels. However, Erastin, a ferroptosis inducer, blocked these neuroprotective effects of AMF. Ferroptosis inhibitor Ferrostatin-1 also attenuated Hcy-induced ferroptosis. Moreover, both AMF and Ferrostatin-1 effectively mitigated Hcy-induced inflammation, which was again antagonized by Erastin. Mechanistically, AMF treatment enhanced SLC7A11/GPX4 axis in Hcy-treated HT22 cells. In conclusion, these findings suggest that AMF possesses neuroprotection against Hcy-induced injury primarily by inhibiting ferroptosis-mediated inflammation, partly through the activation of SLC7A11/GPX4 axis.

Study on the involvement of microglial S100A8 in neuroinflammation and microglia activation during migraine attacks

BACKGROUND

Microglia is the primary source of inflammatory factors during migraine attacks. This study aims to investigate the role of microglia related genes (MRGs) in migraine attacks.

METHODS

The RNA sequencing results of migraineurs and the panglaodb database were used to obtain differentially expressed genes (DEGs) in migraine related to microglia. A migraine rat model was established for validating and localizing of the MRGs, and subsequent screening for target genes was conducted. A shRNA was designed to interference the expression of target genes and administered into the trigeminal ganglion (TG) of rats. Pain sensitivity in rats was evaluated via the hot water tail-flick (HWTF) and formalin-induced pain (FIP) experiments. ELISA was used to quantify the levels of inflammatory cytokines and CGRP. WB and immunofluorescence assays were applied to detect the activation of microglia.

RESULTS

A total of five DEGs in migraine related to microglia were obtained from RNA sequencing and panglaodb database. Animal experiments showed that these genes expression were heightened in the TG and medulla oblongata (MO) of migraine rats. The gene S100A8 co-localized with microglia in both TG and MO. The HWTF and FIP experiments demonstrated that interference with S100A8 alleviated the sense of pain in migraine rats. Moreover, the levels of TNFα, IL-1β, IL-6, and CGRP in the TG and MO of rats in the model rats were increased, and the expression of microglia markers IBA-1, M1 polarization markers CD86 and iNOS was upregulated. Significantly, interference with S100A8 reversed these indicators.

CONCLUSION

Interference with S100A8 in microglia increased the pain threshold during migraine attacks, and inhibited neuroinflammation and microglia activation.

Lactate: A New Target for Brain Disorders

Lactate in the brain is produced endogenously and exogenously. The primary functional cells that produce lactate in the brain are astrocytes. Astrocytes release lactate to act on neurons, thereby affecting neuronal function, through a process known as the astrocyte-neuron shuttle. Lactate affects microglial function as well and inhibits microglia-mediated neuroinflammation. Lactate also provides energy, acts as a signaling molecule, and promotes neurogenesis. This article summarizes the role of lactate in cells, animals, and humans. Lactate is a protective molecule against stress in healthy organisms and in the early stages of brain disorders. Thus, lactate may be a potential therapeutic target for brain disorders. Further research on the role of lactate in microglia may have great prospects. This article provides a new perspective and research direction for the study of lacate in brain disorders.

Albiflorin Attenuates Neuroinflammation and Improves Functional Recovery After Spinal Cord Injury Through Regulating LSD1-Mediated Microglial Activation and Ferroptosis

Spinal cord injury (SCI) is a serious, prolonged, and irreversible injury with few therapeutic options. Albiflorin (AF) possesses powerful pharmacodynamic properties and exerts protective effects against neuroinflammation. However, no research has examined the neuroprotective effect of AF following SCI. Rats were received laminectomy to establish SCI animal model and treated with AF (20 mg/kg and 40 mg/kg). Behavioral experiments were conducted to assess the impacts of AF on motor function after SCI in rats. Hematoxylin-eosin (HE) staining, Nissl staining, and Prussian Blue staining were performed to observe histological changes, neuronal damage, and iron deposition, respectively. Transmission electron microscope was adopted to observe the ultrastructure of spinal cord tissues. Immunofluorescence assay was performed to examine neurons and microglia. ELISA assay was used to examine the production of cytokines. Western blot assay was used to detect the expression level of ferroptosis-related proteins. Microglia BV-2 cells were induced by LPS to mimic the neuroinflammatory condition. Cell viability was assessed by CCK-8 assay, and lipid peroxidase level was measured by C11 BODIPY 581/591 staining. Molecular docking technology was utilized to confirm the relationship between AF and LSD1. AF improved the motor functional recovery after SCI in rats. Meanwhile, AF attenuated neuron apoptosis and microglia activation, reduced the production of pro-inflammatory cytokines and iron accumulation, and inhibited spinal cord ferroptosis following SCI in rats. LSD1 was verified to be a target protein of AF, and AF could concentration-dependently downregulate LSD1 expression in injured spinal cords in vivo and LPS-induced BV-2 cells in vitro. In addition, AF not only inhibited ferroptosis through reducing lipid peroxidase and iron levels and regulating ferroptosis-related proteins, but also inhibited microglial activation and reduced pro-inflammatory cytokines production in LPS-induced BV-2 cells; however, these changes were partly counteracted by LSD1 overexpression. AF could reduce microglial activation and ferroptosis, attenuate neuroinflammation, and improve functional recovery following SCI by downregulating LSD1, providing novel therapeutic strategies for the treatment of SCI.

Neuroinflammation in Parkinson's disease: focus on the relationship between miRNAs and microglia

Parkinson's disease (PD) is a prevalent neurodegenerative disorder that affects the central nervous system (CNS). Neuroinflammation is a crucial factor in the pathological advancement of PD. PD is characterized by the presence of activated microglia and increased levels of proinflammatory factors, which play a crucial role in its pathology. During the immune response of PD, microglia regulation is significantly influenced by microRNA (miRNA). The excessive activation of microglia, persistent neuroinflammation, and abnormal polarization of macrophages in the brain can be attributed to the dysregulation of certain miRNAs. Additionally, there are miRNAs that possess the ability to inhibit neuroinflammation. miRNAs, which are small non-coding epigenetic regulators, have the ability to modulate microglial activity in both normal and abnormal conditions. They also have a significant impact on promoting communication between neurons and microglia.

A critical appraisal of ferroptosis in Alzheimer's and Parkinson's disease: new insights into emerging mechanisms and therapeutic targets

Neurodegenerative diseases represent a pressing global health challenge, and the identification of novel mechanisms underlying their pathogenesis is of utmost importance. Ferroptosis, a non-apoptotic form of regulated cell death characterized by iron-dependent lipid peroxidation, has emerged as a pivotal player in the pathogenesis of neurodegenerative diseases. This review delves into the discovery of ferroptosis, the critical players involved, and their intricate role in the underlying mechanisms of neurodegeneration, with an emphasis on Alzheimer's and Parkinson's diseases. We critically appraise unsolved mechanistic links involved in the initiation and propagation of ferroptosis, such as a signaling cascade resulting in the de-repression of lipoxygenase translation and the role played by mitochondrial voltage-dependent anionic channels in iron homeostasis. Particular attention is given to the dual role of heme oxygenase in ferroptosis, which may be linked to the non-specific activity of P450 reductase in the endoplasmic reticulum. Despite the limited knowledge of ferroptosis initiation and progression in neurodegeneration, Nrf2/Bach1 target genes have emerged as crucial defenders in anti-ferroptotic pathways. The activation of Nrf2 and the inhibition of Bach1 can counteract ferroptosis and present a promising avenue for future therapeutic interventions targeting ferroptosis in neurodegenerative diseases.

Advances in research on immunocyte iron metabolism, ferroptosis, and their regulatory roles in autoimmune and autoinflammatory diseases

Autoimmune diseases commonly affect various systems, but their etiology and pathogenesis remain unclear. Currently, increasing research has highlighted the role of ferroptosis in immune regulation, with immune cells being a crucial component of the body's immune system. This review provides an overview and discusses the relationship between ferroptosis, programmed cell death in immune cells, and autoimmune diseases. Additionally, it summarizes the role of various key targets of ferroptosis, such as GPX4 and TFR, in immune cell immune responses. Furthermore, the release of multiple molecules, including damage-associated molecular patterns (DAMPs), following cell death by ferroptosis, is examined, as these molecules further influence the differentiation and function of immune cells, thereby affecting the occurrence and progression of autoimmune diseases. Moreover, immune cells secrete immune factors or their metabolites, which also impact the occurrence of ferroptosis in target organs and tissues involved in autoimmune diseases. Iron chelators, chloroquine and its derivatives, antioxidants, chloroquine derivatives, and calreticulin have been demonstrated to be effective in animal studies for certain autoimmune diseases, exerting anti-inflammatory and immunomodulatory effects. Finally, a brief summary and future perspectives on the research of autoimmune diseases are provided, aiming to guide disease treatment strategies.

Single-nucleus transcriptome unveils the role of ferroptosis in ischemic stroke

Multiple cell death pathways are involved in neuronal death in ischemic stroke (IS). However, the role of different cell death pathways in different cell types has not been elucidated. By analyzing three single-nucleus RNA sequencing (snRNA-seq) data of IS, we first found that a variety of programmed cell death (PCD) -related genes were significantly changed in different cell types. Based on machine learning and virtual gene knockout, we found that ferroptosis related genes, ferritin heavy chain 1 (Fth1) and ferritin light chain (Ftl1), play a key role in IS. Ftl1 and Fth1 can promote microglia activation, as well as the production of inflammatory factors and chemokines. Cell communication analysis showed that activated microglia could enhance chemotactic peripheral leukocyte infiltration, such as macrophages and neutrophils, through Spp1-Cd44 and App-Cd74 signaling, thereby aggravating brain tissue damage. Furthermore, real-time quantitative polymerase chain reaction (RT-qPCR) showed that P2ry12 and Mef2c were significantly decreased in oxygen-glucose deprivation (OGD) group, while Ftl1, Fth1, Apoe, Ctsb, Cd44 and Cd74 were significantly increased in OGD group. Collectively, our findings suggested targeted therapy against microglia Ftl1 and Fth1 might improve the state of microglia, reduce the infiltration of peripheral immune cells and tissue inflammation, and then improve the ischemic brain injury in mouse.

The antidepressant effects of protein arginine methyltransferase 2 involve neuroinflammation

Protein arginine methyltransferase (PRMT) 2 catalyzes the methylation of arginine residues in histones. Depression is associated with histone methylation; however, more comprehensive research is needed on how PRMT2 regulates depression. The present study aimed to investigate the effects and possible mechanism(s) of PRMT2 overexpression on depression-like behavior induced by chronic unpredictable mild stress (CUMS) in rats, and whether lentivirus-mediated PRMT2 overexpression in the hippocampus suppresses depression-like behavior. Furthermore, the PRMT2 inhibitor MS023 was administered to the animals to investigate whether the antidepressant effect of PRMT2 overexpression could be reversed. Behavioral experiments were performed to detect depression-like behavior in rats. Western blotting was used to determine protein expression levels of PRMT2, histone H3R8 asymmetric dimethylation (H3R8me2a), inducible nitric oxide synthase (iNOS), and arginase 1 (Arg1) in rat hippocampal tissues. Hippocampal microglia and PRMT2 were stained using immunofluorescence techniques. Enzyme-linked immunosorbent assay was used to determine the levels of various inflammatory factors in rat hippocampal tissue. Results of analysis revealed that PRMT2 overexpression in the hippocampus exerted an antidepressant effect. PRMT2 overexpression in the hippocampus reduced the proportion of activated microglia in the hippocampus, upregulated Arg1 and H3R8me2a expression, and downregulated iNOS expression. PRMT2 overexpression in the hippocampus inhibited the release of pro-inflammatory factors and promoted the release of anti-inflammatory factors. In summary, PRMT2 overexpression in the hippocampus promoted the conversion of microglia from the M1 to M2 type, resulting in an antidepressant effect. These results suggest that PRMT2 may be a potential therapeutic target to prevent and treat depression.

Emodin relieves morphine-stimulated BV2 microglial activation and inflammation through the TLR4/NF-κB/NLRP3 pathway

The objective of this study is to disclose the role of emodin, a natural anthraquinone derivative that has been proposed to suppress microglial activation and inflammation, in morphine tolerance. Here, cell counting kit-8 method assayed the viability of BV2 microglial cells treated by ascending concentrations of emodin. In emodin-pretreated BV2 microglial cells challenged with morphine with or without transfection of toll-like receptor 4 (TLR4) overexpression plasmids, transwell assay measured cell migration. Immunofluorescence staining and western blot detected the expression of microglial markers. Inflammatory levels were subjected to ELISA and western blot. BODIPY 581/591 C11 assay estimated lipid reactive oxygen species activity. Iron assay kit examined total iron content. Western blot tested the expression of ferroptosis- and TLR4/nuclear factor-kappaB (NF-κB)/NOD-like receptor 3 (NLRP3) pathway-associated proteins. Molecular docking predicted the binding affinity of emodin to TLR4. Emodin was noted to obstruct the migration, activation, inflammatory response, and ferroptosis of BV2 microglial cells induced by morphine. In addition, emodin had a high binding affinity with TLR4 and inactivated TLR4/NF-κB/NLRP3 pathway in morphine-challenged BV2 microglial cells. Upregulation of TLR4 partially countervailed the protective role of emodin against morphine-elicited BV2 microglial cell migration, activation, inflammation, and ferroptosis. Accordingly, emodin might target TLR4 and act as an inactivator of TLR4/NF-κB/NLRP3 pathway, thus inhibiting BV2 microglial activation and inflammation to mitigate morphine tolerance.

TRIM28 Fosters Microglia Ferroptosis via Autophagy Modulation to Enhance Neuropathic Pain and Neuroinflammation

This study explores the molecular underpinnings of neuropathic pain (NPP) and neuroinflammation, focusing on the role of TRIM28 in the regulation of autophagy and microglia ferroptosis. Leveraging transcriptomic data associated with NPP, we identified TRIM28 as a critical regulator of ferroptosis. Through comprehensive analysis, including Gene Ontology enrichment and protein-protein interaction network assessments, we unveiled GSK3B as a downstream target of TRIM28. Experimental validation confirmed the capacity of TRIM28 to suppress GSK3B expression and attenuate autophagic processes in microglia. We probed the consequences of autophagy and ferroptosis on microglia physiology, iron homeostasis, oxidative stress, and the release of proinflammatory cytokines. In a murine model, we validated the pivotal role of TRIM28 in NPP and neuroinflammation. Our analysis identified 20 ferroptosis regulatory factors associated with NPP, with TRIM28 emerging as a central orchestrator. Experimental evidence affirmed that TRIM28 governs microglial iron homeostasis and cell fate by downregulating GSK3B expression and modulating autophagy. Notably, autophagy was found to influence oxidative stress and proinflammatory cytokine release through the iron metabolism pathway, ultimately fueling neuroinflammation. In vivo experiments provided conclusive evidence of TRIM28-mediated pathways contributing to heightened pain sensitivity in neuroinflammatory states. The effect of TRIM28 on autophagy and microglia ferroptosis drives NPP and neuroinflammation. These findings offer promising avenues for identifying novel therapeutic targets to manage NPP and neuroinflammation.

Second Near-Infrared Macrophage-Biomimetic Nanoprobes for Photoacoustic Imaging of Neuroinflammation

Neuroinflammation is a significant pathological event involving the neurodegenerative process associated with many neurological disorders. Diagnosis and treatment of neuroinflammation in its early stage are essential for the prevention and management of neurological diseases. Herein, we designed macrophage membrane-coated photoacoustic (PA) probes (MSINPs), with targeting specificities based on naturally existing target-ligand interactions for the early diagnosis of neuroinflammation. The second near-infrared dye, IR1061, was doped into silica as the core and was encapsulated with a macrophage membrane. In vitro as well as in vivo, the MSINPs could target inflammatory cells via the inflammation chemotactic effect. PA imaging was used to trace the MSINPs in a neuroinflammation mouse model and showed a great targeted effect of MSINPs in the prefrontal cortex. Therefore, the biomimetic nanoprobe prepared in this study offers a new strategy for PA molecular imaging of neuroinflammation, which can enhance our understanding of the evolution of neuroinflammation in specific brain regions.

The Interplay between Ferroptosis and Neuroinflammation in Central Neurological Disorders

Central neurological disorders are significant contributors to morbidity, mortality, and long-term disability globally in modern society. These encompass neurodegenerative diseases, ischemic brain diseases, traumatic brain injury, epilepsy, depression, and more. The involved pathogenesis is notably intricate and diverse. Ferroptosis and neuroinflammation play pivotal roles in elucidating the causes of cognitive impairment stemming from these diseases. Given the concurrent occurrence of ferroptosis and neuroinflammation due to metabolic shifts such as iron and ROS, as well as their critical roles in central nervous disorders, the investigation into the co-regulatory mechanism of ferroptosis and neuroinflammation has emerged as a prominent area of research. This paper delves into the mechanisms of ferroptosis and neuroinflammation in central nervous disorders, along with their interrelationship. It specifically emphasizes the core molecules within the shared pathways governing ferroptosis and neuroinflammation, including SIRT1, Nrf2, NF-κB, Cox-2, iNOS/NO·, and how different immune cells and structures contribute to cognitive dysfunction through these mechanisms. Researchers' findings suggest that ferroptosis and neuroinflammation mutually promote each other and may represent key factors in the progression of central neurological disorders. A deeper comprehension of the common pathway between cellular ferroptosis and neuroinflammation holds promise for improving symptoms and prognosis related to central neurological disorders.

Functional identification of long non-coding RNAs induced by PM2.5 in microglia through microarray analysis

As a dominating air pollutant, atmospheric fine particulate matter within 2.5 μm in diameter (PM2.5) has attracted increasing attention from the researchers all over the world, which will lead to various adverse effects on the central nervous system (CNS), yet the potential mechanism is unclear. In this study, the microglia (BV2 cell line) were exposed to different concentrations of PM2.5 (5, 10 and 20 μg/cm2) for 24 h. It was found that PM2.5 could result in adverse effects on microglia such as decreased cell viability, structural damage and even cell death. And it was reported that long non-coding RNAs (lncRNAs) could participate in multitudinous neurological diseases. Therefore, the microarray analysis was conducted in order to disclose the underlying neurotoxicity mechanism of PM2.5 by ascertaining the differentially expressed lncRNAs (DElncRNAs). The consequences indicated that the DElncRNAs were enriched in various biological pathways, including ferroptosis, IL-17 signaling pathway and NOD-like receptor signaling pathway. Moreover, the cis- and trans-regulated mRNAs by DElncRNAs as well as the corresponding transcriptional factors (TFs) were observed, such as CEBPA, MYC, MEIS1 and KLF4. In summary, our study supplies some candidate libraries and potential preventive target against PM2.5-induced toxicity through targeting lncRNAs. Furthermore, the post-transcriptional regulation will contribute to the future research on PM2.5-induced neurotoxicity.

Research progress on ferroptosis in the pathogenesis and treatment of neurodegenerative diseases

Globally, millions of individuals are impacted by neurodegenerative disorders including Huntington's disease (HD), amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), and Alzheimer's disease (AD). Although a great deal of energy and financial resources have been invested in disease-related research, breakthroughs in therapeutic approaches remain elusive. The breakdown of cells usually happens together with the onset of neurodegenerative diseases. However, the mechanism that triggers neuronal loss is unknown. Lipid peroxidation, which is iron-dependent, causes a specific type of cell death called ferroptosis, and there is evidence its involvement in the pathogenic cascade of neurodegenerative diseases. However, the specific mechanisms are still not well known. The present article highlights the basic processes that underlie ferroptosis and the corresponding signaling networks. Furthermore, it provides an overview and discussion of current research on the role of ferroptosis across a variety of neurodegenerative conditions.

Role of ferroptosis pathways in neuroinflammation and neurological disorders: From pathogenesis to treatment

Ferroptosis is a newly discovered non-apoptotic and iron-dependent type of cell death. Ferroptosis mainly takes place owing to the imbalance of anti-oxidation and oxidation in the body. It is regulated via a number of factors and pathways both inside and outside the cell. Ferroptosis is closely linked with brain and various neurological disorders (NDs). In the human body, the brain contains the highest levels of polyunsaturated fatty acids, which are known as lipid peroxide precursors. In addition, there is also a connection of glutathione depletion and lipid peroxidation with NDs. There is growing evidence regarding the possible link between neuroinflammation and multiple NDs, such as Alzheimer's disease, amyotrophic lateral sclerosis, Parkinson's disease, Huntington's disease, and stroke. Recent studies have demonstrated that disruptions of lipid reactive oxygen species (ROS), glutamate excitatory toxicity, iron homeostasis, and various other manifestations linked with ferroptosis can be identified in various neuroinflammation-mediated NDs. It has also been reported that damage-associated molecular pattern molecules including ROS are generated during the events of ferroptosis and can cause glial activation via activating neuroimmune pathways, which subsequently leads to the generation of various inflammatory factors that play a role in various NDs. This review summarizes the regulation pathways of ferroptosis, the link between ferroptosis as well as inflammation in NDs, and the potential of a range of therapeutic agents that can be used to target ferroptosis and inflammation in the treatment of neurological disorders.

JE-133 Suppresses LPS-Induced Neuroinflammation Associated with the Regulation of JAK/STAT and Nrf2 Signaling Pathways

Neuroinflammation plays an important role in the pathogenesis of neurodegenerative diseases, and interrupting the microglial-mediated neuroinflammation has been suggested as a promising strategy to delay or prevent the progression of neurodegeneration. In this study, we investigated the effects of JE-133, an optically active isochroman-2H-chromene conjugate containing a 1,3-disubstituted isochroman unit, on lipopolysaccharide (LPS)-induced microglial neuroinflammation and underlying mechanisms both in vitro and in vivo. First, JE-133 treatment decreased LPS-induced overproduction of interleukin-1 beta (IL-1β), interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α), nitrite, and nitric oxide synthase (iNOS) in BV2 microglial cells. Further study revealed that JE-133 downregulated the phosphorylation level of JAK/STAT and upregulated the protein level of Nrf2/HO-1 in LPS-stimulated BV2 microglial cells and verified that JE-133 directly bound to Keap1 by a pull-down assay. Next, JE-133 administration also inhibited neuroinflammation in vivo, as indicated by a reduced CD11b protein level and an overexpressed mRNA level of the pro-inflammatory cytokine TNF-α in the hippocampus of LPS-injected mice. Moreover, the regulative effects of JE-133 on the JAK/STAT and Nrf2/HO-1 pathways were also verified in the hippocampus of LPS-injected mice. Taken together, our study for the first time reports that JE-133 exhibits inhibitory effects against LPS-stimulated neuroinflammation both in vitro and in vivo, which might be associated with the simultaneous regulation of the JAK/STAT and Nrf2 pathways. Our findings may provide important clues for the discovery of effective drug leads/candidates against neuroinflammation-associated neurodegeneration.

Research progress on mechanisms of ischemic stroke: Regulatory pathways involving Microglia

Microglia, as the intrinsic immune cells in the brain, are activated following ischemic stroke. Activated microglia participate in the pathological processes after stroke through polarization, autophagy, phagocytosis, pyroptosis, ferroptosis, apoptosis, and necrosis, thereby influencing the injury and repair following stroke. It has been established that polarized M1 and M2 microglia exhibit pro-inflammatory and anti-inflammatory effects, respectively. Autophagy and phagocytosis in microglia following ischemia are dynamic processes, where moderate levels promote cell survival, while excessive responses may exacerbate neurofunctional deficits following stroke. Additionally, pyroptosis and ferroptosis in microglia after ischemic stroke contribute to the release of harmful cytokines, further aggravating the damage to brain tissue due to ischemia. This article discusses the different functional states of microglia in ischemic stroke research, highlighting current research trends and gaps, and provides insights and guidance for further study of ischemic stroke.

Ferroptosis in Parkinson's disease: Molecular mechanisms and therapeutic potential

Parkinson's Disease (PD) is characterized by the progressive loss of dopaminergic neurons in the substantia nigra (SN), leading to motor and non-motor symptoms. While the exact mechanisms remain complex and multifaceted, several molecular pathways have been implicated in PD pathology, including accumulation of misfolded proteins, impaired mitochondrial function, oxidative stress, inflammation, elevated iron levels, etc. Overall, PD's molecular mechanisms involve a complex interplay between genetic, environmental, and cellular factors that disrupt cellular homeostasis, and ultimately lead to the degeneration of dopaminergic neurons. Recently, emerging evidence highlights ferroptosis, an iron-dependent non-apoptotic cell death process, as a pivotal player in the advancement of PD. Notably, oligomeric α-synuclein (α-syn) generates reactive oxygen species (ROS) and lipid peroxides within cellular membranes, potentially triggering ferroptosis. The loss of dopamine, a hallmark of PD, could predispose neurons to ferroptotic vulnerability. This unique form of cell demise unveils fresh insights into PD pathogenesis, necessitating an exploration of the molecular intricacies connecting ferroptosis and PD progression. In this review, the molecular and regulatory mechanisms of ferroptosis and their connection with the pathological processes of PD have been systematically summarized. Furthermore, the features of ferroptosis in PD animal models and clinical trials targeting ferroptosis as a therapeutic approach in PD patients' management are scrutinized.

Novel Mechanisms of Perioperative Neurocognitive Disorders: Ferroptosis and Pyroptosis

Perioperative neurocognitive disorders (PNDs) are some of the most common postoperative complications among the elderly and susceptible individuals, which significantly worsens the clinical outcome of patients. However, the prevention and treatment strategies of PNDs are difficult to determine and implement since the pathogenesis of PNDs is not well understood. The development of living organisms is associated with active and organized cell death, which is essential for maintaining the homeostasis of life. Ferroptosis is a programmed cell death (different from apoptosis and necrosis) mainly caused by an imbalance in the generation and degradation of intracellular lipid peroxides due to iron overload. Pyroptosis is an inflammatory cell death characterized by the creation of membrane holes mediated by the gasdermin (GSDM) family, followed by cell lysis and the release of pro-inflammatory cytokines. Ferroptosis and pyroptosis are involved in the pathogenesis of various central nervous system (CNS) diseases. Furthermore, ferroptosis and pyroptosis are closely associated with the occurrence and development of PNDs. This review summarizes the main regulatory mechanisms of ferroptosis and pyroptosis and the latest related to PNDs. Based on the available evidence, potential intervention strategies that can alleviate PNDs by inhibiting ferroptosis and pyroptosis have also been provided.

Metabolic reprogramming and polarization of microglia in Parkinson's disease: Role of inflammasome and iron

Parkinson's disease (PD) is a slowly progressive neurodegenerative disease characterized by α-synuclein aggregation and dopaminergic neuronal death. Recent evidence suggests that neuroinflammation is an early event in the pathogenesis of PD. Microglia are resident immune cells in the central nervous system that can be activated into either pro-inflammatory M1 or anti-inflammatory M2 phenotypes as found in peripheral macrophages. To exert their immune functions, microglia respond to various stimuli, resulting in the flexible regulation of their metabolic pathways. Inflammasomes activation in microglia induces metabolic shift from oxidative phosphorylation to glycolysis, and leads to the polarization of microglia to pro-inflammatory M1 phenotype, finally causing neuroinflammation and neurodegeneration. In addition, iron accumulation induces microglia take an inflammatory and glycolytic phenotype. M2 phenotype microglia is more sensitive to ferroptosis, inhibition of which can attenuate neuroinflammation. Therefore, this review highlights the interplay between microglial polarization and metabolic reprogramming of microglia. Moreover, it will interpret how inflammasomes and iron regulate microglial metabolism and phenotypic shifts, which provides a promising therapeutic target to modulate neuroinflammation and neurodegeneration in PD and other neurodegenerative diseases.

Extracellular Vesicles in Chronic Demyelinating Diseases: Prospects in Treatment and Diagnosis of Autoimmune Neurological Disorders

Extracellular vesicles (EVs) represent membrane-enclosed structures that are likely to be secreted by all living cell types in the animal organism, including cells of peripheral (PNS) and central nervous systems (CNS). The ability to cross the blood-brain barrier (BBB) provides the possibility not only for various EV-loaded molecules to be delivered to the brain tissues but also for the CNS-to-periphery transmission of these molecules. Since neural EVs transfer proteins and RNAs are both responsible for functional intercellular communication and involved in the pathogenesis of neurodegenerative diseases, they represent attractive diagnostic and therapeutic targets. Here, we discuss EVs' role in maintaining the living organisms' function and describe deviations in EVs' structure and malfunctioning during various neurodegenerative diseases.