Dectin-1/Syk signaling triggers neuroinflammation after ischemic stroke in mice

Baicalin liposomes ameliorate cerebral ischemia-reperfusion-induced acute lung injury by modulating the inflammatory response

Stroke is the leading cause of death globally, with stroke-associated pneumonia being a major contributor to its high mortality. Among these complications, cerebral ischemia-reperfusion injury-induced acute lung injury (CIR-ALI) is characterized by high morbidity and mortality rate, which causes a great economic burden to the society. The course of CIR-ALI is complex, in which the inflammatory cascade response plays a central role in the pathogenesis of CIR-ALI. Baicalin (BA), a flavonoid extracted from the natural plant Scutellaria baicalensis, exhibits diverse pharmacological effects, including anti-inflammatory and antioxidant properties. In this study, we investigated the therapeutic effects of baicalin and its delivery system baicalin liposome (BA-LP) on CIR-ALI injury. Using in vitro models of BV2 and Raw264.7 cells, as well as an in vivo model established via the wire bolus method, we measured inflammatory factors and pathological injuries in brain and lung tissues to evaluate the intervention effects of BA and BA-LP. In addition, the preliminary analysis of network pharmacology combined with experimental validation in this study preliminarily elucidated that BA and BA-LP may attenuate CIR-ALI by modulating the PI3K/AKT/mTOR pathway.

Inhibition of Dectin-1 alleviates inflammation in early diabetic retinopathy by regulating microglia phenotype

BACKGROUND

Diabetic retinopathy (DR) is a major factor in vision loss in diabetic patients, triggering a series of pathological changes. At present, the treatment methods for diabetic retinopathy are limited. There is an urgent need to further explore its mechanism to bring more treatment options to patients.There is increasing evidence that microglia activation plays a crucial role in inflammatory DR. The C type lectin receptor Dectin-1 is known to play an important role in the inflammatory regulation of microglia, however, its role and mechanism in DR remains unclear. This study aims to elucidate the possible mechanisms through which Dectin-1 influences the inflammatory response in high glucose(HG) stimulated microglia and its impact on retinal inflammation during the early stages of DR.

METHODS

Human microglial cells (HMC3) were stimulated with HG (25 mmol/L), and a streptozotocin (STZ)induced C57BL/6J mouse model was established to simulate DR. To investigate the role of Dectin-1 in HMC3 cells and its underlying molecular mechanisms, we employed western blotting, quantitative realtime PCR (qRT-PCR), hematoxylineosin (H&E) staining, and immunofluorescence analysis.

RESULTS

Our findings revealed that Dectin-1 levels were elevated in microglia stimulated by HG, playing a pivotal role in cell polarization and the induction of inflammatory factors in vitro. In vivo experiments conducted on STZ induced diabetic mice demonstrated an increased expression of Dectin-1 in retinal tissues. This elevation further promoted the expression of pro inflammatory factors, such as TNF-α, IL-1β, and iNOS, triggering an inflammatory response and causing damage to the retina. Notably, inhibiting Dectin-1 reversed these detrimental effects, ultimately contributing to the delay in the progression of DR. Our investigation also uncovered a significant interaction between Dectin-1 and the downstream pro-inflammatory pathway NF-κB. This interaction occurred through the activation of spleen tyrosine kinase (Syk), both in vitro and in vivo.

CONCLUSIONS

In summary, our research strongly suggests that Dectin-1 plays a crucial pro-inflammatory role in early DR. This mechanismis, at least in part, mediated through the Syk/NF-κB pathway. Consequently, inhibition of Dectin-1 is expected to become a potential therapeutic target for delaying DR.

Morus alba L. alleviates influenza viral pneumonia. Evidences of its mechanism of action

BACKGROUND

Viral pneumonia is an infection of the lungs caused by numerous different viruses, which can lead to severe respiratory distress and even life-threatening conditions. In the absence of specific treatments for viral pneumonia, natural traditional medicines offer an alternative in terms of innovative drug therapies. Morus alba L. (common name mulberry leaf) is a Chinese medicine that has been used clinically as an antiviral.

PURPOSE

The therapeutic effect of M. alba on viral pneumonia was investigated along with its mechanism of action.

METHODS

Network pharmacology and molecular docking were used to analyze the mechanism of action of M. alba in the treatment of viral pneumonia. Histology, immunofluorescence, Western blotting, qPCR, and flow cytometry were used to evaluate the protective effect of MLE (the ethanol extract of Morus alba L.) on PR8 (A/Puerto Rico/8/1934 H1N1, a murine lung-adapted influenza A virus strain)-induced viral pneumonia. SiRNA was used to validate the relationship between the therapeutic effects of MLE on viral pneumonia and the target Syk (a crucial non-receptor tyrosine kinase).

RESULTS

MLE alleviated PR8-induced viral pneumonia by reducing inflammatory factor expression in the lungs, decreasing NF-κB pathway activation, slowing oxidative damage in the lungs, and inhibiting lung tissue cell apoptosis. Meanwhile, MLE for viral pneumonia was significantly associated with Syk targets. Notably, knockdown of the Syk gene not only reduced the therapeutic effect of MLE, but also suppressed PR8-induced viral pneumonia.

CONCLUSION

MLE can alleviate PR8-induced viral pneumonia through inhibiting the Dectin-1/Syk pathway.

Dectin-1 participates in neuroinflammation and dopaminergic neurodegeneration through synergistic signaling crosstalk with TLR4

Neuroinflammation mediated by microglial activation plays a prominent role in the pathogenesis of Parkinson's disease (PD). Dendritic cell-associated C-type lectin-1 (Dectin-1) is a pattern recognition receptor that is involved in innate immunity. However, the role of Dectin-1 on dopaminergic neuronal damage remains unclear. Our results demonstrated that the expression of Dectin-1 was significantly increased in the microglia of the LPS-induced PD mouse model. Inhibition of Dectin-1 by laminarin (LAM) attenuated LPS-induced dopaminergic neuronal damage in substantia nigra (SN) and behavioral deficits and promoted the phenotypic transformation of microglia from M1 to M2. Moreover, inhibition or knockdown of Dectin-1 significantly decreased LPS-induced phosphorylation of Syk and P65 as well as the production of COX-2 and iNOS in BV2 cells. Knockdown of Syk also significantly decreased LPS-induced protein expressions of COX-2 and iNOS. Mechanistically, both TLR4 inhibitor and NF-κB inhibitor could antagonize LPS-induced Dectin-1 expression. Chromatin immunoprecipitation (ChIP) assays showed a physical binding of NF-κB/P65 to Dectin-1 promoter, which further indicated the regulatory effect of toll-like receptor 4 (TLR4)/NF-κB signaling pathway on Dectin-1 expression. Furthermore, the present study provided the first evidence that Dectin-1 activation by hot-alkali treated depleted zymosan (d-Zymosan) could induce dopaminergic neurotoxicity and motor dysfunction, and promote up-regulation of TLR4, iNOS and Iba-1 in C57BL/6J mice. In conclusion, Dectin-1-Syk synergistic signaling crosstalk with TLR4/NF-κB promotes and maintains inflammatory phenotypes of M1 microglia which induces dopaminergic neuronal damage in SN. These findings provide novel insights into the pivotal role of Dectin-1 in neuroinflammation, suggesting its potential as a novel therapeutic target for PD.

Rutin resists Aspergillus fumigatus keratitis by activating Nrf2/HO-1 pathway, inhibiting Dectin-1/p-Syk pathway and affecting fungal structures

Fungal keratitis (FK) is a severe vision-threatening eye disease. The fungal invasiveness and excessive inflammatory response contribute to corneal tissue damage. Rutin (RT) possesses anti-inflammatory, antimicrobial, antioxidant, and improved wound-healing characteristics. This study aimed to evaluate antifungal, anti-inflammatory, and therapeutic effects of RT in FK. The results showed that RT exerted antifungal effects by inhibiting fungal growth, altering hyphal morphology, destroying biofilm, and disrupting fungal cellular structures. RT exhibited anti-inflammatory benefits by suppressing the Dectin-1/p-Syk pathway, activating the Nrf2/HO-1 pathway, and decreasing the expression of inflammatory factors in vivo and in vitro. RT demonstrated therapeutic effects by reducing clinical scores, fungal load, macrophage recruitment, and neutrophil activity. In conclusion, RT exhibited anti-inflammatory, antifungal, and therapeutic effects in Aspergillus fumigatus keratitis, and has the potential to become a novel therapeutic strategy for FK.

Clec7a Signaling in Microglia Promotes Synapse Loss Associated with Tauopathy

Alzheimer's disease (AD) pathogenesis involves progressive synaptic degeneration, a process potentially driven by maladaptive microglial pruning activity. While synaptic loss is a hallmark of AD, the molecular signals triggering pathological microglia-mediated synaptic engulfment remain elusive. Clec7a-a key marker of disease-associated microglia (DAM)-is known to activate spleen tyrosine kinase (SYK) signaling, enhancing Aβ phagocytosis and neuroprotective functions in 5×FAD models. However, its role in regulating synapse-microglia interactions under tauopathic conditions remains undefined. Our analysis revealed a progressive activation of the Clec7a-SYK signaling axis in the hippocampus of PS19 tauopathy mice, correlating with disease progression. Spatial mapping demonstrated a significant co-localization of Clec7a with hippocampal microglia, suggesting cell-autonomous signaling. The pharmacological inhibition of Clec7a achieved multimodal therapeutic effects by attenuating microglial hyperreactivity, suppressing neuroinflammatory cytokine release, and restoring physiological synaptic turnover. Mechanistically, we identified MD2 as a synaptic "eat-me" signal on tauopathy-related synapses, recruiting Clec7a+ microglia to drive aberrant synaptic elimination in PS19 mice. Strikingly, Clec7a blockade rescued hippocampal-dependent memory deficits in behavioral tests. These findings position Clec7a as a context-dependent therapeutic target, with inhibition strategies showing particular promise for tauopathy-related synaptic degeneration.

A Fluorescent Probe for Imaging and Treating S-Nitrosation Stress in OGD/R Cells

Protein S-nitrosation, a redox post-translational modification elicited by nitric oxide (NO), is essential for modulating diverse protein functions and signaling pathways. Dysregulation of S-nitrosation is implicated in various pathological processes, including oxygen-glucose deprivation/reperfusion (OGD/R) injury, a widely used model for ischemia-reperfusion diseases. The dynamic changes in S-nitrosothiols (SNOs) during ischemia-reperfusion highlight the need for theranostic strategies to monitor and modulate SNO levels based on pathological progression. However, to date, no theranostic strategies have been reported for addressing dysregulated SNO in disease models, particularly in OGD/R conditions. Here, we report the development of a selective probe P-EHC, which could specifically react with SNOs to release EHC, not only exhibiting turn-on fluorescence with high quantum yield and good water solubility but also demonstrating macrophage migration inhibitory factor (MIF) inhibitory activity. In an OGD/R model of SH-SY5Y cells, we observed elevated SNO levels by using live-cell confocal imaging. Treatment of P-EHC significantly reduced intracellular reactive oxygen species (ROS), lowered total NOx species, and improved cell viability in the OGD/R model. In summary, the simplicity and versatility of P-EHC suggest its broad applicability for monitoring SNO in various biological models and therapeutic contexts, particularly in ischemia-reperfusion diseases.

Changes in border-associated macrophages after stroke: single-cell sequencing analysis

ABSTRACT

Border-associated macrophages are located at the interface between the brain and the periphery, including the perivascular spaces, choroid plexus, and meninges. Until recently, the functions of border-associated macrophages have been poorly understood and largely overlooked. However, a recent study reported that border-associated macrophages participate in stroke-induced inflammation, although many details and the underlying mechanisms remain unclear. In this study, we performed a comprehensive single-cell analysis of mouse border-associated macrophages using sequencing data obtained from the Gene Expression Omnibus (GEO) database (GSE174574 and GSE225948). Differentially expressed genes were identified, and enrichment analysis was performed to identify the transcription profile of border-associated macrophages. CellChat analysis was conducted to determine the cell communication network of border-associated macrophages. Transcription factors were predicted using the 'pySCENIC' tool. We found that, in response to hypoxia, border- associated macrophages underwent dynamic transcriptional changes and participated in the regulation of inflammatory-related pathways. Notably, the tumor necrosis factor pathway was activated by border-associated macrophages following ischemic stroke. The pySCENIC analysis indicated that the activity of signal transducer and activator of transcription 3 (Stat3) was obviously upregulated in stroke, suggesting that Stat3 inhibition may be a promising strategy for treating border-associated macrophages-induced neuroinflammation. Finally, we constructed an animal model to investigate the effects of border-associated macrophages depletion following a stroke. Treatment with liposomes containing clodronate significantly reduced infarct volume in the animals and improved neurological scores compared with untreated animals. Taken together, our results demonstrate comprehensive changes in border-associated macrophages following a stroke, providing a theoretical basis for targeting border-associated macrophages-induced neuroinflammation in stroke treatment.

Interleukin-1 Receptor-Associated Kinase-3 Aggravates Neuroinflammatory Injury After Intracerebral Hemorrhage via Activation NF-κB/IL-17A Pathway in Mice

Background

Neuroinflammatory reactions are crucial factors in secondary brain damage following intracerebral hemorrhage (ICH). Although previous studies have shown that IRAK3 is involved in immune responses, the potential effects of IRAK3 on ICH remain unclear.

Methods

Collagenase IV-induced ICH mouse model. Western blotting was used to determine the expression of IRAK3 at different time points following ICH. Immunofluorescence was used to investigate the cellular localization of IRAK3. The ICH model was treated with recombinant human IRAK3 (rh-IRAK3) or IRAK3 siRNA via an intracerebroventricular injection. The effect of IRAK3 on ICH mice was assessed by Western blotting and short-term and long-term neurological function evaluation. RNA-seq was performed to explore the mechanism by which IRAK3 promotes inflammation after ICH. The mechanisms of IRAK3 and neuroinflammation will be further investigated by Western blotting, qRT-PCR and immunofluorescence. Recombinant IL-17A was used to investigate the connection between IRAK3 and the NF-κB/IL-17A signaling pathway in vivo and in vitro experiments.

Results

The expression of IRAK3 increased, peaking at 24 h, followed by a subsequent decrease after ICH. IRAK3 is mainly expressed in the microglia. RNA-seq analysis revealed 1,797 differentially expressed genes around the perihematomal brain tissue after IRAK3 siRNA treatment, with multiple inflammatory pathways being downregulated. Rh-IRAK3 treatment resulted in upregulation of the levels of inflammatory cytokines around the perihematomal tissue and exacerbated neurological function deficits. Furthermore, IRAK3 siRNA treatment markedly decreased the expression of inflammatory cytokines and microglial activation via the NF-κB/IL-17A signaling pathway. Recombinant IL-17A exacerbated the inflammatory response in vivo and in vitro; however, IRAK3 knockdown reversed this process.

Conclusion

IRAK3 aggravates neuroinflammation by activating the NF-κB/IL-17A signaling pathway, thereby exacerbating neurological deficits following ICH. Therefore, inhibition IRAK3 may be a promising approach for treating ICH.

Ghrelin Induces Ferroptosis Resistance and M2 Polarization of Microglia to Alleviate Neuroinflammation and Cognitive Impairment in Alzheimer's Disease

Microglial polarization and ferroptosis are important pathological features in Alzheimer's disease (AD). Ghrelin, a brain-gut hormone, has potential neuroprotective effects in AD. This study aimed to explore the potential mechanisms by which ghrelin regulates the progression of AD, as well as the crosstalk between microglial polarization and ferroptosis. Mouse BV2 microglial cells and male mice were treated with beta-amyloid (Aβ) (1-42) to simulate the AD environment. Microglia ferroptosis was measured by detecting levels of ferroptosis-related proteins (SLC7A11, GPX4, FTL1, and FTH1), metabolic markers (ROS, MDA, GSH, SOD), and observing mitochondrial morphological changes. Microglial polarization was evaluated by measuring levels of inflammatory markers and surface markers. The impact of ghrelin on Aβ1-42-exposed microglia was assessed by coupling with the ferroptosis activator Erastin. Cognitive impairment in AD mice was evaluated through behavioral tests. Tissue staining was applied to determine neuronal damage. In Aβ1-42-exposed microglia, ghrelin upregulated the protein expression of SLC7A11, GPX4, FTL1 and FTH1, reduced ROS and MDA levels, and elevated GSH and SOD levels through the BMP6/SMAD1 pathway. Ghrelin alleviated mitochondrial structural damage. Additionally, ghrelin reduced levels of pro-inflammatory factors and CD86, while increasing levels of anti-inflammatory factors and CD206. Erastin reversed the effects of ghrelin on ferroptosis and phenotypic polarization in Aβ1-42-exposed microglia. In AD mice, ghrelin ameliorated abnormal behavior, neuroinflammation, and plaque deposition. Ghrelin attenuated iNOS/IBA1-positive expression and enhanced Arg-1/IBA1-positive expression in the hippocampus. Ghrelin induces microglial M2 polarization by inhibiting microglia ferroptosis, thereby alleviating neuroinflammation. Our results indicate that ghrelin may serve as a promising potential agent for treating cognitive impairment in AD.

Therapeutic potential of microglial SMEK1 in regulating H3K9 lactylation in cerebral ischemia-reperfusion

Acute ischemic stroke (AIS) triggers immune responses and neuroinflammation, contributing to brain injury. Histone lactylation, a metabolic stress-related histone modification, plays a critical role in various diseases, but its involvement in cerebral ischemia remains unclear. This study utilized a transient middle cerebral artery occlusion/reperfusion (MCAO/R) model and an oxygen-glucose deprivation/reoxygenation (OGD/R) model to investigate the role of microglial histone lactylation in ischemia-reperfusion injury. Lactate overload post-AIS increased histone lactylation, while reduced SMEK1 expression in microglia correlated with elevated lactate and neuroinflammation. Microglia-specific SMEK1 deficiency enhanced lactate production by inhibiting the pyruvate dehydrogenase kinase 3-pyruvate dehydrogenase (PDK3-PDH) pathway, increasing H3 lysine 9 lactylation (H3K9la), activating Ldha and Hif-1α transcription, and promoting glycolysis. SMEK1 overexpression improved neurological recovery in ischemic mice. This study highlights SMEK1 as a novel regulator of histone lactylation and a potential therapeutic target for mitigating neuroinflammation and enhancing recovery after AIS.

CLEC7A Knockdown Alleviates Ischemic Stroke by Inhibiting Pyroptosis and Microglia Activation

BACKGROUND

Ischemic stroke (IS) is the leading cause of mortality worldwide. Herein, we aimed to identify novel biomarkers and explore the role of C-type lectin domain family 7 member A (CLEC7A) in IS.

METHODS

Differentially expressed genes (DEGs) were screened using the GSE106680, GSE97537, and GSE61616 datasets, and hub genes were identified through construction of protein-protein interaction networks. An IS model was established by middle cerebral artery occlusion and reperfusion (MCAO/R). Neural function was assessed using triphenyl tetrazolium chloride, hematoxylin-eosin, and terminal deoxynucleotidyl transferase-mediated nick-end labeling. A cell counting kit was used to detect cell viability following oxygen-glucose deprivation/reperfusion (OGD/R). Inflammatory factors were detected using enzyme-linked immunosorbent assay. The mRNA and protein expression levels were detected using reverse transcription-quantitative polymerase chain reaction and western blotting, respectively.

RESULTS

Fc fragment of Immunoglobulin G (IgG) receptor IIIa (FCGR3A), Fc fragment of Immunoglobulin E (IgE) receptor Ig (FCER1G), Complement component 5a receptor 1 (C5AR1), CLEC7A, Plasminogen activator, urokinase (PLAU), and C-C motif chemokine ligand 6 (CCL6) were identified as important hub genes, from which CLEC7A was selected as the primary subject of this study. The activation of microglia and pyroptosis were observed in MCAO/R model with increased levels of interleukin (IL)-1β, IL-18, tumor necrosis factor-α, and lactate dehydrogenase. CLEC7A knockdown was found to promote cell viability in BV2 cells and inhibiting pyroptosis in HT22 cells. CLEC7A knockdown in microglia also decreased infarct volume and neurological deficit scores, and alleviated injury and neuronal apoptosis in IS rats. CLEC7A knockdown inhibited pyroptosis and microglial activation in the MCAO/R model. A pyroptosis activator reversed the effect of CLEC7A knockdown on the viability of OGD/R-treated HT22 cells.

CONCLUSION

CLEC7A is a promising biomarker of IS. CLEC7A knockdown alleviates IS by inhibiting pyroptosis and microglial activation.

Dectin-1 participates in the immune-inflammatory response to mouse Aspergillus fumigatus keratitis by modulating macrophage polarization

Aim

The aim of this study was to investigate whether Dectin-1 influences the immune-inflammatory response in A. fumigatus keratitis by modulating macrophage polarization.

Methods

1. The models of 1-day, 3-day, and 5-day of fungal keratitis were established in SPF C57BL/6 mice after stimulation by A. fumigatus. Dectin-1 agonist (curdlan) and antagonist (laminaran) were injected separately in the mouse subconjunctivae for 1 day in the established mouse model of A. fumigatus keratitis; PBS was used as the control. Inflammation of the mouse cornea was observed under a slit lamp to obtain a clinical score. 2. The expression of M1 (TNF-α, INOS, IL-6, IL-12) and M2 (Arg-1, IL-10, Fizz-1, Ym-1) cytokine-encoding mRNAs was quantified by RT-PCR. 3. Changes in the number of macrophages and expression of M1 and M2 macrophages in mouse corneas detected by immunofluorescence and flow cytometry. 4. Pre-treatment of RAW264.7 cells with MAPK cell signaling pathway inhibitors SB203580 (p38 inhibitor, 10µM), U0126 (ERK inhibitor, 20µM), SP600125 (JNK inhibitor, 10µM) and DMSO separately for 2 h, and stimulated by A. fumigatus for 12 h. Changes in the mRNA expression of M1 and M2 cytokines in the macrophages were quantified by RT-PCR.

Results

1. With curdlan pre-treatment, mouse corneal inflammation worsened, and the clinical score increased after infection. In contrast, in the laminaran pre-treated group, corneal inflammation was alleviated and the clinical score decreased significantly compared to the PBS group after infection. 2. Compared with the control group, the expression levels of macrophage phenotype-related M1 and M2 cytokine mRNAs increased significantly 1, 3, and 5 days after A. fumigatus infected the corneas of mice. 3. With curdlan pre-treatment, the expression of mRNAs encoding M1 cytokines increased, while those encoding M2 cytokines decreased in the cornea compared to the PBS group. In contrast, after infection, mRNA levels for M1 cytokines decreased significantly and those for M2 cytokines increased in the cornea of the laminaran pre-treated group compared to the PBS group. 4. The number of macrophages in the corneal stroma of mice in the curdlan pretreatment group increased significantly compared with the PBS group, while in the laminaran pretreatment group this number decreased significantly. 5. The results of flow cytometry showed that after 3 days of mouse corneal A. fumigatus infection, the number of macrophages in the mouse A. fumigatus model in the curdlan pretreatment group was increased (10.4%) and the number of macrophages in the mouse A. fumigatus model in the laminaran pretreatment group (6.31%), when compared with the AF+FBS group (7.91%). The proportion of M1-type macrophages was increased in the curdlan pretreated group (55.6%) compared to the AF+FBS group (51.2%), the proportion of laminaran pretreatment group had a decreased proportion of M1-type macrophages (46.8%); while M2-type macrophages were the opposite of M1-type: the proportion of M2-type macrophages was 49.2% in the AF+FBS group, the proportion of M2-type macrophages was decreased in the curdlan pretreatment group (44.0%), and the proportion of M2-type macrophages was increased in the laminaran pretreatment group (53.5%). 6. Expression of M1 and M2 cytokine-encoding mRNAs decreased and increased, respectively, after infection, in the RAW264.7 cells pre-treated with MAPK pathway inhibitors, compared to the control.

Conclusion

In a mouse model of A. fumigatus keratitis, Dectin-1 can affect macrophage recruitment and polarization, may regulate macrophage phenotype-associated factor changes through the MAPK signaling pathway.

Exploring the correlation between innate immune activation of inflammasome and regulation of pyroptosis after intracerebral hemorrhage: From mechanism to treatment

Stroke has emerged as the primary cause of disability and death globally in recent years. Intracerebral hemorrhage (ICH), a particularly severe kind of stroke, is occurring in an increasing number of people. The two main clinical treatments for ICH now in use are conservative pharmaceutical therapy and surgical intervention, both of which have risks and drawbacks. Consequently, it is crucial to look into the pathophysiology of ICH and consider cutting-edge therapeutic approaches. Recent research has revealed that pyroptosis is a newly identified type of cell death distinguished by the break of the cell membrane and the discharge of pro-inflammatory substances through different routes. Following ICH, glial cells experience pyroptosis, which worsens neuroinflammation. Hence, the onset and progression of ICH are strongly linked to pyroptosis, which is facilitated by different inflammasomes. It is essential to conduct a comprehensive investigation of ICH damage processes and uncover new targets for treatment. The impact and function of pyroptosis in ICH, as well as the activation and regulation of inflammasomes and their mediated pyroptosis pathways will be fully discussed in this review.

Transcriptomics and Metabolomics Unveil the Neuroprotection Mechanism of AnGong NiuHuang (AGNH) Pill Against Ischaemic Stroke Injury

As a famous prescription in China, AnGong NiuHuang (AGNH) pill exerts good neuroprotection for ischaemic stroke (IS), but its mechanism is still unclear. In this study, the neuroprotection of AGNH was evaluated in the rat IS model which were established with the surgery of middle cerebral artery occlusion (MCAO), and the potential mechanism was elucidated by transcriptomic analysis and metabolomic analysis. AGNH treatment obviously decreased the infarct volume and Zea-Longa 5-point neurological deficit scores, improved the survival percentage of rats, regional cerebral blood flow (rCBF), and rat activity distance and activity time. Transcriptomics showed that AGNH exerted its anti-inflammatory effects by affecting the regulatory network including Tyrobp, Syk, Tlr2, Myd88 and Ccl2 as the core. Integrating transcriptomics and metabolomics identified 8 key metabolites regulated by AGNH, including L-histidine, L-serine, L-alanine, fumaric acid, malic acid, and N-(L-arginino) succinate, 1-pyrroline-4-hydroxy-2-carboxylate and 1-methylhistamine in the rats with IS. Additionally, AGNH obviously reduced Tyrobp, Syk, Tlr2, Myd88 and Ccl2 at both the mRNA and protein levels, decreased IL-1β, KC-GRO, IL-13, TNF-α, cleaved caspase 3 and p65 nucleus translocation, but increased IκBα expression. Network pharmacology analysis showed that quercetin, beta-sitosterol, baicalein, naringenin, acacetin, berberine and palmatine may play an important role in protecting against IS. Taken together, this study reveals that AGNH reduced neuroinflammation and protected against IS by inhibiting Tyrobp/Syk and Tlr2/Myd88, as well as NF-κB signalling pathway and regulating multiple metabolites.

Knockout of Dectin-1 does not modify disease onset or progression in a MATR3 S85C knock-in mouse model of ALS

Microglia have been increasingly implicated in neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). Dectin-1, encoded by the Clec7a gene, is highly upregulated in a specific microglial response state called disease-associated microglia (DAM) in various neurodegenerative conditions. However, the role of Dectin-1 in ALS is undetermined. Here, we show that Clec7a mRNA upregulation occurs in central nervous system (CNS) regions that exhibit neurodegeneration in a MATR3 S85C knock-in mouse model (Matr3 S85C/S85C ) of ALS. Furthermore, a significant increase in the number of Dectin-1+ microglia coincides with the onset of motor deficits, and this number increases with disease progression. We demonstrate that the knockout of Dectin-1 does not affect survival, motor function, neurodegeneration, or microglial responses in Matr3 S85C/S85C mice. These findings suggest that Dectin-1 does not play a role in modifying ALS onset or progression.

The anti-inflammatory effects of itaconate and its derivatives in neurological disorders

Almost 16 % of the global population is affected by neurological disorders, including neurodegenerative and cerebral neuroimmune diseases, triggered by acute or chronic inflammation. Neuroinflammation is recognized as a common pathogenic mechanism in a wide array of neurological conditions including Alzheimer's disease, Parkinson's disease, postoperative cognitive dysfunction, stroke, traumatic brain injury, and multiple sclerosis. Inflammatory process in the central nervous system (CNS) can lead to neuronal damage and neuronal apoptosis, consequently exacerbating these diseases. Itaconate, an immunomodulatory metabolite from the tricarboxylic acid cycle, suppresses neuroinflammation and modulates the CNS immune response. Emerging human studies suggest that itaconate levels in plasma and cerebrospinal fluid may serve as biomarkers associated with inflammatory responses in neurological disorders. Preclinical studies have shown that itaconate and its highly cell-permeable derivatives are promising candidates for preventing and treating neuroinflammation-related neurological disorders. The underlying mechanism may involve the regulation of immune cells in the CNS and neuroinflammation-related signaling pathways and molecules including Nrf2/KEAP1 signaling pathway, reactive oxygen species, and NLRP3 inflammasome. Here, we introduce the metabolism and function of itaconate and the synthesis and development of its derivatives. We summarize the potential impact and therapeutic potential of itaconate and its derivatives on brain immune cells and the associated signaling pathways and molecules, based on preclinical evidence via various neurological disorder models. We also discuss the challenges and potential solutions for clinical translation to promote further research on itaconate and its derivatives for neuroinflammation-related neurological disorders.

Echinatin protects from ischemic brain injury by attenuating NLRP3-related neuroinflammation

BACKGROUND

Microglia-mediated neuroinflammation is the major contributor to the secondary brain injury of ischemic stroke. NLRP3 is one of the major components of ischemia-induced microglial activation. Echinatin, a chalcone found in licorice, was reported to have the activity of anti-inflammation and antioxidant. However, the relative study of echinatin in microglia or ischemic stroke is still unclear.

METHODS

We intravenously injected echinatin or vehicle into adult ischemic male C57/BL6J mice induced by 60-min transient middle cerebral artery occlusion (tMCAO). The intraperitoneal injection was performed 4.5 h after reperfusion and then daily for 2 more days. Infarct size, blood brain barrier (BBB) leakage, neurobehavioral tests, and microglial-mediated inflammatory reaction were examined to assess the outcomes of echinatin treatment. LPS and LPS/ATP stimulation on primary microglia were used to explore the underlying anti-inflammatory mechanism of echinatin.

RESULTS

Echinatin treatment efficiently decreased the infarct size, alleviated blood brain barrier (BBB) damage, suppressed microglial activation, reduced the production of inflammatory factors (e.g., IL-1β, IL-6, IL-18, TNF-α, iNOS, COX2), and relieved post-stroke neurological defects in tMCAO mice. Mechanistically, we found that echinatin could suppress the NLRP3 assembly and reduce the production of inflammatory mediators independently of NF-κB and monoamine oxidase (MAO).

CONCLUSION

Based on our study, we have identified echinatin as a promising therapeutic strategy for the treatment of ischemic stroke.

Activating transcription factor 6 alleviates secondary brain injury by increasing cystathionine γ-lyase expression in a rat model of intracerebral hemorrhage

BACKGROUND

Intracerebral hemorrhage (ICH) comprises primary and secondary injuries, the latter of which induces increased inflammation and apoptosis and is more severe. Activating transcription factor 6 (ATF6) is a type-II transmembrane protein in the endoplasmic reticulum (ER). ATF6 target genes could improve ER homeostasis, which contributes to cryoprotection. Hence, we predict that ATF6 will have a protective effect on brain tissue after ICH.

METHOD

The ICH rat model was generated through autologous blood injection into the right basal ganglia, the expression of ATF6 after ICH was determined by WB and IF. The expression of ATF6 was effectively controlled by means of intervention, and a series of measures was used to detect cell death, neuroinflammation, brain edema, blood-brain barrier and other indicators after ICH. Finally, the effects on long-term neural function of rats were measured by behavioral means.

RESULT

ATF6 was significantly increased in the ICH-induced brain tissues. Further, ATF6 was found to modulate the expression of cystathionine γ-lyase (CTH) after ICH. Upregulation of ATF6 attenuated neuronal apoptosis and inflammation in ICH rats, along with mitigation of ICH-induced brain edema, blood-brain barrier deterioration, and cognitive behavior defects. Conversely, ATF6 genetic knockdown induced effects counter to those aforementioned.

CONCLUSIONS

This study thereby emphasizes the crucial role of ATF6 in secondary brain injury in response to ICH, indicating that ATF6 upregulation may potentially ameliorate ICH-induced secondary brain injury. Consequently, ATF6 could serve as a promising therapeutic target to alleviate clinical ICH-induced secondary brain injuries.

Myeloid C-type lectin receptors in innate immune recognition

C-type lectin receptors (CLRs) expressed by myeloid cells constitute a versatile family of receptors that play a key role in innate immune recognition. Myeloid CLRs exhibit a remarkable ability to recognize an extensive array of ligands, from carbohydrates and beyond, and encompass pattern-associated molecular patterns (PAMPs), damage-associated molecular patterns (DAMPs), and markers of altered self. These receptors, classified into distinct subgroups, play pivotal roles in immune recognition and modulation of immune responses. Their intricate signaling pathways orchestrate a spectrum of cellular responses, influencing processes such as phagocytosis, cytokine production, and antigen presentation. Beyond their contributions to host defense in viral, bacterial, fungal, and parasitic infections, myeloid CLRs have been implicated in non-infectious diseases such as cancer, allergies, and autoimmunity. A nuanced understanding of myeloid CLR interactions with endogenous and microbial triggers is starting to uncover the context-dependent nature of their roles in innate immunity, with implications for therapeutic intervention.

Self-adjuvant Astragalus polysaccharide-based nanovaccines for enhanced tumor immunotherapy: a novel delivery system candidate for tumor vaccines

The study of tumor nanovaccines (NVs) has gained interest because they specifically recognize and eliminate tumor cells. However, the poor recognition and internalization by dendritic cells (DCs) and insufficient immunogenicity restricted the vaccine efficacy. Herein, we extracted two molecular-weight Astragalus polysaccharides (APS, 12.19 kD; APSHMw, 135.67 kD) from Radix Astragali and made them self-assemble with OVA257-264 directly forming OVA/APS integrated nanocomplexes through the microfluidic method. The nanocomplexes were wrapped with a sheddable calcium phosphate layer to improve stability. APS in the formed nanocomplexes served as drug carriers and immune adjuvants for potent tumor immunotherapy. The optimal APS-NVs were approximately 160 nm with uniform size distribution and could remain stable in physiological saline solution. The FITC-OVA in APS-NVs could be effectively taken up by DCs, and APS-NVs could stimulate the maturation of DCs, improving the antigen cross-presentation efficiency in vitro. The possible mechanism was that APS can induce DC activation via multiple receptors such as dectin-1 and Toll-like receptors 2 and 4. Enhanced accumulation of APS-NVs both in draining and distal lymph nodes were observed following s.c. injection. Smaller APS-NVs could easily access the lymph nodes. Furthermore, APS-NVs could markedly promote antigen delivery efficiency to DCs and activate cytotoxic T cells. In addition, APS-NVs achieve a better antitumor effect in established B16-OVA melanoma tumors compared with the OVA+Alum treatment group. The antitumor mechanism correlated with the increase in cytotoxic T cells in the tumor region. Subsequently, the poor tumor inhibitory effect of APS-NVs on the nude mouse model of melanoma also confirmed the participation of antitumor adaptive immune response induced by NVs. Therefore, this study developed a promising APS-based tumor NV that is an efficient tumor immunotherapy without systemic side effects.

Probucol protects against brain damage caused by intra-neural pyroptosis in rats with vascular dementia through inhibition of the Syk/Ros pathway

BACKGROUND

Neuronal injury in chronic cerebral hypoperfusion (CCH) is the main pathogenic factor of vascular dementia (VD). Clinically, there isn't a drug specifically for VD; instead, the majority of medications used to treat Alzheimer's disease (AD) are also used to treat VD. Based on the proven anti-inflammatory and antioxidant effects of Probucol, we hypothesized that it may have therapeutic effects on VD, but more research is required to determine its exact mechanism of action.

METHODS

In vivo experiment: We used SD rats and most commonly used bilateral carotid artery occlusion (2-VO) in VD for modeling. After successful modeling, SD rats were given Probucol 3.5 mg/kg/day for 8 weeks to evaluate the therapeutic effect. In vitro experiment: BV-2 microglia of rats were cultured and divided into Control group and Probucol group. Each group was treated with hypoxia-hypoglycemia, hypoxia-hypoglycemia hydrogen peroxide and hypoxia-hypoglycemia hydrogen peroxide Syk inhibitor respectively.

RESULTS

The results of immunofluorescence and Western blot showed that Probucol could significantly improve the cognitive impairment induced by CCH, and the neuronal damage was also attenuated. On the one hand, the underlying mechanism of Probucol was to reduce oxidative stress and cell apoptosis of hippocampal neurons by inhibiting the expression of phosphorylated spleen tyrosine kinase (P-Syk); On the other hand, it exerted a protective effect by reducing NLRP3-dependent cell pyroptosis and inhibiting neuroinflammation induced by microglia activation.

CONCLUSION

Probucol could reduce oxidative stress and cell apoptosis by inhibiting the Syk/ROS signaling pathway, thereby improving CCH-induced cognitive impairment in vitro and in vivo.

Methods for evaluating gait associated dynamic balance and coordination in rodents

Balance is the dynamic and unconscious control of the body's centre of mass to maintain postural equilibrium. Regulated by the vestibular system, head movement and acceleration are processed by the brain to adjust joints. Several conditions result in a loss of balance, including Alzheimer's Disease, Parkinson's Disease, Menière's Disease and cervical spondylosis, all of which are caused by damage to certain parts of the vestibular pathways. Studies about the impairment of the vestibular system are challenging to carry out in human trials due to smaller study sizes limiting applications of the results and a lacking understanding of the human balance control mechanism. In contrast, more controlled research can be performed in animal studies which have fewer confounding factors than human models and allow specific conditions that affect balance to be replicated. Balance control can be studied using rodent balance-related behavioural tests after spinal or brain lesions, such as the Basso, Beattie and Bresnahan (BBB) Locomotor Scale, Foot Fault Scoring System, Ledged Beam Test, Beam Walking Test, and Ladder Beam Test, which are discussed in this review article along with their advantages and disadvantages. These tests can be performed in preclinical rodent models of femoral nerve injury, stroke, spinal cord injury and neurodegenerative diseases.

Dectin1 contributes to hypertensive vascular injury by promoting macrophage infiltration through activating the Syk/NF-κB pathway

Vascular injury is an early manifestation leading to end-organ damage in hypertension pathogenesis, which involves a macrophage-associated immune response. Dendritic cell-associated C-type lectin-1 (Dectin1) is a pivotal player in regulating inflammation-mediated cardiovascular disease. However, its role in hypertension-induced vascular damage and the underlying mechanisms remain unclear. We hypothesized that Dectin1 might accelerate angiotensin II (Ang II)- or deoxycorticosterone acetate-salt (DOCA-salt)-induced vascular injury through proinflammatory actions in macrophages. Macrophage Dectin1 was upregulated in mouse aortic tissues stimulated with Ang II. In the peripheral blood, Ang II also increased CD11b+F4/80+ macrophages in mice. In our constructed Dectin1 knockout mice, Dectin1 deletion protected against Ang II-induced EB extravasation and aortic wall thickness. Deficiency of Dectin1 or its pharmacological inhibition considerably improved fibrosis and inflammation responses, accompanied by a reduction in M1 macrophage polarization as well as proinflammatory cytokines and chemokines induced by Ang II or DOCA-salt. Through the bone marrow (BM) transplantation assay, these effects were verified in the wild type mice reconstituted with Dectin1-deficient BM cells. Mechanistically, Ang II promoted Dectin1 homodimerization, thereby triggering the spleen tyrosine kinase/nuclear factor kappa B pro-inflammatory cascade to induce the expression of inflammatory factors and chemokines in vivo and in vitro. In conclusion, Dectin1 has an essential role in the pathogenic procedure of Ang II-stimulated or DOCA-salt-induced vascular damage in mice and represents a promising therapeutic target for cardiovascular diseases.

Identification of Clec7a as the therapeutic target of rTMS in alleviating Parkinson's disease: targeting neuroinflammation

Parkinson's disease (PD) is a neurodegenerative disease. Repetitive transcranial magnetic stimulation (rTMS) is a therapeutic tool in PD. High-throughput sequencing was performed to screen potential therapeutic targets in unilaterally 6-hydroxydopamine (6-OHDA)-lesioned rats. The candidate gene, Clec7a, was screened out and validated. Clec7a is a pattern recognition receptor involved in neuroinflammation. The higher expression of Clec7a was observed in the substantia nigra (SN) and striatum of PD rats with dopaminergic neurons damage and was mainly localized in the microglial. Adeno-associated virus (AAV)-mediated specific knockdown of Clec7a in microglial alleviated 6-OHDA induced motor deficits and nigrostriatal dopaminergic neuron damage of rats, as evidenced by the increase of tyrosine hydroxylase (TH) -positive neurons in SN, as well as dopaminergic nerve fibers in the striatum. Clec7a knockdown restrained the neuroinflammation by suppressing inflammatory factors (IFN-γ, TNF-α, IL-1β, IL-18, and IL-6) release in SN, which might result from enhanced Arg-1 expression (M2 polarization) and defective inducible nitric oxide synthase (iNOS) expression (M1 polarization). The same phenomena were also observed in the LPS inflammatory rat model of PD. In vitro, α-synuclein fibrils induced upregulation of Clec7a expression and microglia polarization to a pro-inflammatory state of BV2 cells, leading to increased release of cytokines. However, Clec7a knockdown reversed those changes and induced a shift to an anti-inflammatory phenotype in BV2 cells. In conclusion, our study suggested that Clec7a was involved in PD pathogenesis, and its inhibition might protect rats from PD by depressing neuroinflammation through microglial polarization.

Levo-tetrahydropalmatine ameliorates neuropathic pain by inhibiting the activation of the Clec7a-MAPK/NF-κB-NLRP3 inflammasome axis

BACKGROUND

Because of the complex pathogenesis of neuropathic pain (NP), the therapeutic efficacy of existing drugs is not satisfactory. Accumulating studies have indicated that neuroinflammation may play a key role in NP onset and progression. Levo-tetrahydropalmatine (l-THP) has been extensively used for relieving chronic pain for decades. However, its potential mechanisms against NP have not yet been fully elucidated.

PURPOSE

Exploring and elucidating the therapeutic effect and pharmacological mechanism of l-THP in treating NP.

METHODS

RNA-seq and bioinformatics analyses were carried out to identify effective target profiling of I-THP in chronic constrictive injury (CCI) rats. The I-THP related hub targets and signaling pathways were obtained via bioinformatics analysis, then subjected to in-depth analyses through experiments in vivo. A gain-of-function study further confirmed the role of Clec7a in l-THP-mediated pain relief. Finally, the interaction between l-THP and Clec7a was verified through molecular docking and surface plasmon resonance (SPR).

RESULTS

l-THP treatment effectively alleviated mechanical and thermal allodynia in NP model rats. Functionally, the I-THP effective targets were mainly enriched in inflammatory response-related pathways. Furthermore, Clec7a-MAPK/NF-κB-NLRP3 inflammasome axis was selected as one of the potential pathways of l-THP against NP. Mechanically, l-THP markedly reduced CCI-induced Clec7a overexpression, significantly inhibited the Clec7a-triggered phosphorylation of MAPK and NF-κB-p65, and decreased the expression of pyroptosis-related protein NLRP3 and Caspase-1-p20. The analgesic effect of l-THP on NP was partly eliminated when transfecting the overexpression vector virus pLVSO5Clec7a. Importantly, molecular docking and SPR data revealed that l-THP directly binds with the Clec7a protein.

CONCLUSION

This study is the first to indicate that l-THP may exert an analgesic effect through inhibiting neuroinflammation via the Clec7a-MAPK/NF-κB-NLRP3 inflammasome axis, supporting the clinical utility of l-THP in NP therapy.

Bioinformatics strategies to identify differences in molecular biomarkers for ischemic stroke and myocardial infarction

Ischemic strokes (ISs) are commonly treated by intravenous thrombolysis using a recombinant tissue plasminogen activator; however, successful treatment can only occur within 3 hours after the stroke. Therefore, it is crucial to determine the causes and underlying molecular mechanisms, identify molecular biomarkers for early diagnosis, and develop precise preventive treatments for strokes. We aimed to clarify the differences in gene expression, molecular mechanisms, and drug prediction approaches between IS and myocardial infarction (MI) using comprehensive bioinformatics analysis. The pathogenesis of these diseases was explored to provide directions for future clinical research. The IS (GSE58294 and GSE16561) and MI (GSE60993 and GSE141512) datasets were downloaded from the Gene Expression Omnibus database. IS and MI transcriptome data were analyzed using bioinformatics methods, and the differentially expressed genes (DEGs) were screened. A protein-protein interaction network was constructed using the STRING database and visualized using Cytoscape, and the candidate genes with high confidence scores were identified using Degree, MCC, EPC, and DMNC in the cytoHubba plug-in. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses of the DEGs were performed using the database annotation, visualization, and integrated discovery database. Network Analyst 3.0 was used to construct transcription factor (TF) - gene and microRNA (miRNA) - gene regulatory networks of the identified candidate genes. The DrugBank 5.0 database was used to identify gene-drug interactions. After bioinformatics analysis of IS and MI microarray data, 115 and 44 DEGS were obtained in IS and MI, respectively. Moreover, 8 hub genes, 2 miRNAs, and 3 TFs for IS and 8 hub genes, 13 miRNAs, and 2 TFs for MI were screened. The molecular pathology between IS and MI presented differences in terms of GO and KEGG enrichment pathways, TFs, miRNAs, and drugs. These findings provide possible directions for the diagnosis of IS and MI in the future.

Mechanisms of polydatin against spinal cord ischemia-reperfusion injury based on network pharmacology, molecular docking and molecular dynamics simulation

BACKGROUND

Polydatin has shown considerable pharmacological activities in ischemia-reperfusion injuries of various organs. However, its effects and mechanisms in spinal cord ischemia-reperfusion injury have not been fully established. In this study, the mechanisms of polydatin against spinal cord ischemia-reperfusion injury were investigated via network pharmacology, molecular docking and molecular dynamics simulation.

METHODS

Spinal cord ischemia-reperfusion injury-related targets were obtained from the GeneCards database, while polydatin-related action targets were obtained from the CTD and SwissTarget databases. A protein-protein interaction network of potential targets was constructed using the String platform. After selecting the potential key targets, GO functional enrichment and KEGG pathway enrichment analyses were performed via the Metascape database, and a network map of "drug-target-pathway-disease" constructed. The relationships between polydatin and various key targets were assessed via molecular docking. Molecular dynamics simulation was conducted for optimal core protein-compound complexes obtained by molecular docking.

RESULTS

Topological analysis of the PPI network revealed 14 core targets. GO functional enrichment analysis revealed that 435 biological processes, 12 cell components and 29 molecular functions were enriched while KEGG pathway enrichment analysis revealed 91 enriched signaling pathways. Molecular docking showed that polydatin had the highest binding affinity for MAPK3, suggesting that MAPK3 is a key target of polydatin against spinal cord ischemia-reperfusion injury. Molecular dynamics simulations revealed good binding abilities between polydatin and MAPK3.

CONCLUSIONS

Polydatin exerts its effects on spinal cord ischemia-reperfusion injury through multiple targets and pathways. MAPK3 may be a key target of polydatin in spinal cord ischemia-reperfusion injury.

Remote limb ischemic postconditioning inhibits microglia pyroptosis by modulating HGF after acute ischemia stroke

The repetitive inflation-deflation of a blood pressure cuff on a limb is known as remote limb ischemic postconditioning (RIPostC). It prevents brain damage induced by acute ischemia stroke (AIS). Pyroptosis, executed by the pore-forming protein gasdermin D (GSDMD), is a type of regulated cell death triggered by proinflammatory signals. It contributes to the pathogenesis of ischemic brain injury. However, the effects of RIPostC on pyroptosis following AIS remain largely unknown. In our study, linear correlation analysis confirmed that serum GSDMD levels in AIS patients upon admission were positively correlated with NIHSS scores. RIPostC treatment significantly reduced GSDMD level compared with patients without RIPostC at 3 days post-treatment. Besides, middle cerebral artery occlusion (MCAO) surgery was performed on C57BL/6 male mice and RIPostC was induced immediately after MCAO. We found that RIPostC suppressed the activation of NLRP3 inflammasome to reduce the maturation of GSDMD, leading to decreased pyroptosis in microglia after AIS. Hepatocyte growth factor (HGF) was identified using the high throughput screening. Importantly, HGF siRNA, exogenous HGF, and ISG15 siRNA were used to reveal that HGF/ISG15 is a possible mechanism of RIPostC regulation in vivo and in vitro.

Tau seeding and spreading in vivo is supported by both AD-derived fibrillar and oligomeric tau

Insoluble fibrillar tau, the primary constituent of neurofibrillary tangles, has traditionally been thought to be the biologically active, toxic form of tau mediating neurodegeneration in Alzheimer's disease. More recent studies have implicated soluble oligomeric tau species, referred to as high molecular weight (HMW), due to their properties on size-exclusion chromatography, in tau propagation across neural systems. These two forms of tau have never been directly compared. We prepared sarkosyl-insoluble and HMW tau from the frontal cortex of Alzheimer patients and compared their properties using a variety of biophysical and bioactivity assays. Sarkosyl-insoluble fibrillar tau comprises abundant paired-helical filaments (PHF) as quantified by electron microscopy (EM) and is more resistant to proteinase K, compared to HMW tau, which is mostly in an oligomeric form. Sarkosyl-insoluble and HMW tau are nearly equivalent in potency in HEK cell bioactivity assay for seeding aggregates, and their injection reveals similar local uptake into hippocampal neurons in PS19 Tau transgenic mice. However, the HMW preparation appears to be far more potent in inducing a glial response including Clec7a-positive rod microglia in the absence of neurodegeneration or synapse loss and promotes more rapid propagation of misfolded tau to distal, anatomically connected regions, such as entorhinal and perirhinal cortices. These data suggest that soluble HMW tau has similar properties to fibrillar sarkosyl-insoluble tau with regard to tau seeding potential, but may be equal or even more bioactive with respect to propagation across neural systems and activation of glial responses, both relevant to tau-related Alzheimer phenotypes.

Tau seeding and spreading in vivo is supported by both AD-derived fibrillar and oligomeric tau

Insoluble fibrillar tau, the primary constituent of neurofibrillary tangles, has traditionally been thought to be the biologically active, toxic form of tau mediating neurodegeneration in Alzheimer's disease. More recent studies have implicated soluble oligomeric tau species, referred to as high molecular weight (HMW) due to its properties on size exclusion chromatography, in tau propagation across neural systems. These two forms of tau have never been directly compared. We prepared sarkosyl insoluble and HMW tau from the frontal cortex of Alzheimer patients and compared their properties using a variety of biophysical and bioactivity assays. Sarkosyl insoluble fibrillar tau is comprised of abundant paired helical filaments (PHF) as quantified by electron microscopy (EM), and is more resistant to proteinase K, compared to HMW tau which is mostly in an oligomeric form. Sarkosyl insoluble and HMW tau are nearly equivalent in potency in a HEK cell bioactivity assay for seeding aggregates and their injection reveals similar local uptake into hippocampal neurons in PS19 Tau transgenic mice. However, the HMW preparation appears to be far more potent in inducing a glial response including Clec7a-positive rod-microglia in the absence of neurodegeneration or synapse loss and promotes more rapid propagation of misfolded tau to distal, anatomically connected regions, such as entorhinal and perirhinal cortices. These data suggest that soluble HMW tau has similar properties to fibrillar sarkosyl insoluble tau with regard to tau seeding potential but may be equal or even more bioactive with respect to propagation across neural systems and activation of glial responses, both relevant tau-related Alzheimer phenotypes.

A comparative study of the neuroprotective effects of dl-3-n-butylphthalide and edaravone dexborneol on cerebral ischemic stroke rats

INTRODUCTION

DL-3-n-butylphthalide (NBP) and edaravone dexborneol (Eda-Dex) are two promising reagents for stroke treatment. However, the impacts of NBP and Eda-Dex on poststroke mental deficits are still poorly understood. In this study, we aimed to investigate and compare the influences of NBP and Eda-Dex on neurological function and cognitive behavior in rats with ischemic stroke.

METHODS

An ischemic stroke model was established by middle cerebral artery occlusion (MCAO). After peritoneal administration of the drugs, the rats were subjected to neurological deficit evaluation, cerebral blood flow (CBF) assays, cerebral infarct area evaluations or behavioral tests. Brain tissues were collected and further analyzed by enzyme-linked immunosorbent assay (ELISA), western blotting or immunohistochemistry.

RESULTS

NBP and Eda-Dex significantly decreased the neurological score, reduced the cerebral infarct area and improved CBF. Behavioral changes as assessed in the sucrose preference test, novel object recognition test, and social interaction test were significantly alleviated by NBP and Eda-Dex in rats with ischemic stroke. Moreover, NBP and Eda-Dex significantly suppressed inflammation by targeting the nuclear factor kappa-B/inducible nitric oxide synthase (NF-κB/iNOS) pathway and significantly inhibited oxidative stress by targeting the kelch-1ike ECH-associated protein l/nuclear factor erythroid 2-related factor 2 (Keap1/Nrf2) pathway. In addition, NBP and Eda-Dex distinctly suppressed the activation of microglia and astrocytes and improved neuronal viability in the ischemic brain.

CONCLUSIONS

NBP and Eda-Dex improved neurological function and alleviated cognitive disorders in rats with ischemic stroke by synergistically inhibiting inflammation and oxidative stress.

Spleen tyrosine kinase (SYK) signals are implicated in cardio-cerebrovascular diseases

Post-translational modifications regulate numerous biochemical reactions and functions through covalent attachment to proteins. Phosphorylation, acetylation and ubiquitination account for over 90% of all reported post-translational modifications. As one of the tyrosine protein kinases, spleen tyrosine kinase (SYK) plays crucial roles in many pathophysiological processes and affects the pathogenesis and progression of various diseases. SYK is expressed in tissues outside the hematopoietic system, especially the heart, and is involved in the progression of various cardio-cerebrovascular diseases, such as atherosclerosis, heart failure, diabetic cardiomyopathy, stroke and others. Knowledge on the role of SYK in the progress of cardio-cerebrovascular diseases is accumulating, and many related mechanisms have been discovered and validated. This review summarizes the role of SYK in the progression of various cardio-cerebrovascular diseases, and aims to provide a theoretical basis for future experimental and clinical research targeting SYK as a therapeutic option for these diseases.

Dectin-1 deficiency alleviates diabetic cardiomyopathy by attenuating macrophage-mediated inflammatory response

Cardiovascular diseases are the primary cause of mortality in patients with diabetes and obesity. Hyperglycemia and hyperlipidemia in diabetes alters cardiac function, which is associated with broader cellular processes such as aberrant inflammatory signaling. Recent studies have shown that a pattern recognition receptor called Dectin-1, expressed on macrophages, mediates pro-inflammatory responses in innate immunity. In the present study, we examined the role of Dectin-1 in the pathogenesis of diabetic cardiomyopathy. We observed increased Dectin-1 expression in heart tissues of diabetic mice and localized the source to macrophages. We then investigated the cardiac function in Dectin-1-deficient mice with STZ-induced type 1 diabetes and high-fat-diet-induced type 2 diabetes. Our results show that Dectin-1 deficient mice are protected against diabetes-induced cardiac dysfunction, cardiomyocyte hypertrophy, tissue fibrosis, and inflammation. Mechanistically, our studies show that Dectin-1 is important for cell activation and induction of inflammatory cytokines in high-concentration glucose and palmitate acid (HG + PA)-challenged macrophages. Deficiency of Dectin-1 generate fewer paracrine inflammatory factors capable of causing cardiomyocyte hypertrophy and fibrotic responses in cardiac fibroblasts. In conclusion, this study provides evidence that Dectin-1 mediates diabetes-induced cardiomyopathy through regulating inflammation. Dectin-1 may be a potential target to combat diabetic cardiomyopathy.

Syk inhibitors protect against microglia-mediated neuronal loss in culture

Microglia are brain macrophages and play beneficial and/or detrimental roles in many brain pathologies because of their inflammatory and phagocytic activity. Microglial inflammation and phagocytosis are thought to be regulated by spleen tyrosine kinase (Syk), which is activated by multiple microglial receptors, including TREM2 (Triggering Receptor Expressed on Myeloid Cells 2), implicated in neurodegeneration. Here, we have tested whether Syk inhibitors can prevent microglia-dependent neurodegeneration induced by lipopolysaccharide (LPS) in primary neuron-glia cultures. We found that the Syk inhibitors BAY61-3606 and P505-15 (at 1 and 10 μM, respectively) completely prevented the neuronal loss induced by LPS, which was microglia-dependent. Syk inhibition also prevented the spontaneous loss of neurons from older neuron-glia cultures. In the absence of LPS, Syk inhibition depleted microglia from the cultures and induced some microglial death. However, in the presence of LPS, Syk inhibition had relatively little effect on microglial density (reduced by 0-30%) and opposing effects on the release of two pro-inflammatory cytokines (IL-6 decreased by about 45%, TNFα increased by 80%). Syk inhibition also had no effect on the morphological transition of microglia exposed to LPS. On the other hand, inhibition of Syk reduced microglial phagocytosis of beads, synapses and neurons. Thus, Syk inhibition in this model is most likely neuroprotective by reducing microglial phagocytosis, however, the reduced microglial density and IL-6 release may also contribute. This work adds to increasing evidence that Syk is a key regulator of the microglial contribution to neurodegenerative disease and suggests that Syk inhibitors may be used to prevent excessive microglial phagocytosis of synapses and neurons.

Dectin-1 plays a deleterious role in high fat diet-induced NAFLD of mice through enhancing macrophage activation

The innate immune response and inflammation contribute to hepatic steatosis and non-alcoholic fatty liver disease (NAFLD). Dectin-1 is a pathogen recognition receptor in innate immunity. In this study, we investigated the role of Dectin-1 in the pathogenesis of NAFLD. We first showed that Dectin-1 expression was significantly elevated in liver tissues of patients with NASH. NAFLD was induced in mice by feeding high fat diet (HFD) for 24 weeks. At the end of treatment, mice were sacrificed, and their blood and liver tissues were collected for analyses. We showed HFD feeding also increased liver Dectin-1 levels in mice, associated with macrophage infiltration. Either gene knockout or co-administration of a Dectin-1 antagonist laminarin (150 mg/kg twice a day, ip, from 16^th week to 24^th week) largely protected the livers from HFD-induced lipid accumulation, fibrosis, and elaboration of inflammatory responses. In primary mouse peritoneal macrophages (MPMs), challenge with palmitate (PA, 200 μM), an abundant saturated fatty acid found in NAFLD, significantly activated Dectin-1 signaling pathway, followed by transcriptionally regulated production of pro-inflammatory cytokines. Dectin-1 was required for hepatic macrophage activation and inflammatory factor induction. Condition media generated from Dectin-1 deficient macrophages failed to cause hepatocyte lipid accumulation and hepatic stellate activation. In conclusion, this study provides the primary evidence supporting a deleterious role for Dectin-1 in NAFLD through enhancing macrophage pro-inflammatory responses and suggests that it can be targeted to prevent inflammatory NAFLD.

Circulating MicroRNA Profiling Identifies Distinct MicroRNA Signatures in Acute Ischemic Stroke and Transient Ischemic Attack Patients

Transient ischemic attack (TIA) refers to a momentary neurologic deficit caused by focal cerebral, spinal or retinal ischemic insult. TIA is associated with a high risk of impending acute ischemic stroke (AIS), a neurologic dysfunction characterized by focal cerebral, spinal or retinal infarction. Understanding the differences in molecular pathways in AIS and TIA has merit for deciphering the underlying cause for neuronal deficits with long-term effects and high risks of morbidity and mortality. In this study, we performed comprehensive investigations into the circulating microRNA (miRNA) profiles of AIS (n = 191) and TIA (n = 61) patients. We performed RNA-Seq on serum samples collected within 24 hrs of clinical diagnosis and randomly divided the study populations into discovery and validation cohorts. We identified a panel of 11 differentially regulated miRNAs at FDR < 0.05. Hsa-miR-548c-5p, -20a-5p, -18a-5p, -484, -652-3p, -486-3p, -24-3p, -181a-5p and -222-3p were upregulated, while hsa-miR-500a-3p and -206 were downregulated in AIS patients compared to TIA patients. We also probed the previously validated gene targets of our identified miRNA panel to highlight the molecular pathways affected in AIS. Moreover, we developed a multivariate classifier with potential utilization as a discriminative biomarker for AIS and TIA patients. The underlying molecular pathways in AIS compared to TIA may be explored further in functional studies for therapeutic targeting in clinical translation.

TJ-M2010-5, a novel CNS drug candidate, attenuates acute cerebral ischemia-reperfusion injury through the MyD88/NF-κB and ERK pathway

Background: Cerebral ischemia-reperfusion injury (CIRI) inevitably occurs after vascular recanalization treatment for ischemic stroke. The accompanying inflammatory cascades have a major impact on outcome and regeneration after ischemic stroke. Evidences have demonstrated that TLR/MyD88/NF-κB signaling contributes to CIRI. This study aimed to investigate the druggability of MyD88 in the central nervous system (CNS) and the neuroprotective and anti-neuroinflammatory effects of the MyD88 inhibitor TJ-M2010-5 on CIRI. Methods: A middle cerebral artery occlusion (MCAO) model was used to simulate CIRI in mice. BV-2 cells were stimulated with oxygen glucose deprivation/reoxygenation (OGD/R) or lipopolysaccharide, and SH-SY5Y cells were induced by OGD/R in vitro. Neurological deficit scores and cerebral infarction volumes were evaluated. Immunofluorescence staining was performed to measure neuronal damage and apoptosis in the brain. The anti-neuroinflammatory effect of TJ-M2010-5 was evaluated by analyzing the expression of inflammatory cytokines, activation of microglia, and infiltration of peripheral myeloid cells. The expression of proteins of the MyD88/NF-κB and ERK pathway was detected by Simple Western. The concentrations of TJ-M2010-5 in the blood and brain were analyzed by liquid chromatography-mass spectrometry. Results: The cerebral infarction volume decreased in mice treated with TJ-M2010-5, with the most prominent decrease being approximately 80% of the original infarction volume. Neuronal loss and apoptosis were reduced following TJ-M2010-5 treatment. TJ-M2010-5 inhibited the infiltration of peripheral myeloid cells and the activation of microglia. TJ-M2010-5 also downregulated the expression of inflammatory cytokines and inhibited the MyD88/NF-κB and ERK pathway. Furthermore, TJ-M2010-5 showed good blood-brain barrier permeability and no neurotoxicity. Conclusion: TJ-M2010-5 has an excellent therapeutic effect on CIRI as a novel CNS drug candidate by inhibiting excessive neuroinflammatory responses.

Apelin-13 Improves Cognitive Impairment and Repairs Hippocampal Neuronal Damage by Activating PGC-1α/PPARγ Signaling

Alzheimer's disease (AD) is a complex neurodegenerative disease that is prevalent around the world. Both Apelin-13 and proliferator-activated receptor-γ (PPARγ)/PPARγ co-activator 1α (PGC-1α) are regarded as candidate targets for treating AD. The investigation examined whether Apelin-13 exerts neuroprotective effects via PGC-1α/PPARγ signaling. In this study, Apelin-13 improved cognitive deficits in AD mice, while SR-18,292 (a PGC-1α inhibitor) interfered with the therapeutic effects of Apelin-13. Mechanistically, Apelin-13, PGC-1α and PPARγ were decreased in AD mice and oxygen-glucose deprivation (OGD)-induced neuronal cells. Apelin-13 bound to PGC-1α and negatively regulated the expression of PGC-1α and PPARγ. In turn, PGC-1α accelerated the accumulation of Apelin-13 and PPARγ. Additionally, neuronal apoptosis was inhibited, and the abundance of apoptosis-related proteins (Bax, Bcl-2, and cleaved caspase 3) was induced. The content of reactive oxygen species (ROS), malondialdehyde (MDA) and superoxide dismutase (SOD) fluctuated. The level of inflammatory factors (interleukin-6, IL-6, IL-10, tumor necrosis factor-α, TNF-α) was regulated. In short, Apelin-13 exerted anti-apoptosis, anti-oxidant stress and anti-inflammatory effects. Interestingly, PGC-1α silencing promoted neuronal apoptosis, oxidant stress and inflammation, and overexpression of PGC-1α exhibited the opposite. More importantly, inhibition of PGC-1α attenuated Apelin-13-enhanced cognitive impairment and neuronal damage. Therefore, our findings suggested that Apelin-13 exerted neuroprotective effects in part via the PGC-1α/PPARγ pathway.

Disruption of C/EBPβ-Clec7a axis exacerbates neuroinflammatory injury via NLRP3 inflammasome-mediated pyroptosis in experimental neuropathic pain

BACKGROUND

Growing evidence shows that C-Type Lectin Domain Containing 7A (Clec7a) may be involved into neuroinflammatory injury of various neurological diseases. However, its roles in neuropathic pain remain unclear.

METHODS

A chronic constriction injury (CCI) rat model was constructed, and gene expression profilings in spinal cord tissues of CCI-insulted rats were detected by both microarray and RNA-seq studies. A series of bioinformatics analyses identified C/EBPβ-Clec7a to be a candidate axis involved into neuropathic pain. Then, its roles in mechanical allodynia, and pathological and molecular changes during CCI progression were determined by various gain-of-function and loss-of-function experiments in vivo and in vitro.

RESULTS

Significant upregulation of Clec7a at both mRNA and protein levels were verified in spinal cord tissues of CCI-insulted rats. Clec7a knockdown markedly attenuated CCI-induced mechanical allodynia, obstructed Syk, ERK and JNK phosphorylation, inhibited NLRP3 inflammasome and caspase-1 activation, GSDMD cleavage, and consequently reduced the release of pro-inflammatory cytokines (all P < 0.05). Mechanically, the rat Clec7a promoter was predicted to bind with transcription factor C/EBPβ, confirmed by Luciferase assay and ChIP-qPCR. Both in vivo and in vitro assays demonstrated that C/EBPβ knockdown significantly suppressed CCI- or LPS/ATP-induced Clec7a upregulation, and subsequently reduced Syk, ERK and JNK phosphorylation, NLRP3 oligomerization, caspase-1 activation, GSDMD expression and pyroptosis, which were markedly reversed by the co-transfection of Clec7a expression vector.

CONCLUSIONS

This pre-clinical investigation reveals that C/EBPβ-Clec7a axis may be a potential target for relieving neuropathic pain through alleviating neuroinflammation, paving its way for clinical translation as a promising approach for neuropathic pain therapy.

Comprehensive Analysis of Long Non-Coding RNAs N4-Acetylcytidine in Alzheimer's Disease Mice Model Using High-Throughput Sequencing

BACKGROUND

N4-acetylcytidine (ac4C), an important posttranscriptional modification, is involved in various disease processes. Long noncoding RNAs (lncRNAs) regulate gene expression mainly through epigenetic modification, transcription, and posttranscriptional modification. Alzheimer's disease (AD) is a neurodegenerative disease characterized by amyloidosis of the brain. However, the role of lncRNA ac4C modification in AD remains unclear.

OBJECTIVE

In this study, we investigated the association between ac4C modification and AD, and the underlying mechanisms of ac4C modification in AD.

METHODS

The male 9-month-old APP/PS1 double transgenic mice, age- and sex-matched wild type (WT) mice were used in this study. Then, ac4C-RIP-seq and RNA-seq were used to comprehensively analyze lncRNA ac4C modification in AD mice. The lncRNA-miRNA-mRNA regulatory networks using Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analyses showed the regulatory relationships among these three lncRNAs and AD.

RESULTS

The results showed that there were 120 significantly different ac4C peaks located on 102 lncRNAs in AD, of which 55 were hyperacetylated and 47 were hypoacetylated. Simultaneously, 231 differentially expressed lncRNAs were identified, including 138 upregulated lncRNAs and 93 downregulated lncRNAs. Moreover, 3 lncRNAs, lncRNA Gm26508, lncRNA A430046D13Rik, and lncRNA 9530059O14Rik, showed significant changes in both the ac4C and RNA levels using conjoint analysis.

CONCLUSION

The abundance of lncRNA ac4C modification is significantly different in AD and indicates that lncRNA ac4C is associated with the occurrence and development of AD, which could provide a basis for further exploration of the related regulatory mechanisms.

BDNF-overexpressing MSCs delivered by hydrogel in acute ischemic stroke treatment

Background

Ischemic stroke treatment is a challenge worldwide. The efficacy and safety of mesenchymal stem cells (MSCs) for stroke have been confirmed. However, poor survival of MSCs in the ischemic environment limits the therapy efficacy. Changes in MSC status in the ischemic environment after transplantation is difficult to monitor. This study aimed to deliver brain-derived neurotrophic factor (BDNF)-overexpressing MSCs by hydrogel (H-B-MSCs) to promote recovery after ischemic stroke.

Methods

MSCs were transfected with lentivirus carrying luc2 and BDNF cassette. The properties of hydrogel were tested after synthesis with thiolated gelatin (Gel-SH), thiolated hyaluronic acid (HA-SH), and polyethylene glycol diacrylate (PEGDA). Oxygen-glucose deprivation (OGD) test was carried out to confirm the protective effects of hydrogel in the ischemic environment. Three days after stroke induction, H-B-MSCs, hydrogel carrying MSCs (H-MSCs), or phosphate-buffered saline (PBS) was injected into the brains of mice, respectively. Bioluminescence imaging (BLI) was performed at 3, 7, 14, and 21 days post-cell-transplantation to monitor the dynamic status of MSCs. In the meantime, histology, quantitative polymerase chain reaction (qPCR), enzyme-linked immunosorbent assay (ELISA), western blot, and behavior tests were carried out at different time points.

Results

Hydrogel with good biocompatibility was synthesized. Lentivirus transfection significantly increased the expression of BDNF. BDNF-MSCs could be tracked by BLI in vitro. In vitro OGD/reperfusion (OGD/R) test results suggested that MSCs carried by hydrogel could survive longer in an environment with low oxygen and glucose. H-B-MSCs significantly improved functional recovery after ischemic stroke. Furthermore, H-B-MSCs treatment promoted neurogenesis, white matter recovery, and angiogenesis after ischemic stroke. MSC dynamics could be monitored in vivo with BLI.

Conclusions

We effectively established a robust MSC delivery system with hydrogel. Prolonged survival of transplanted BDNF-MSCs with a hydrogel delivery system could promote the recovery of ischemic stroke via the continuous release of BDNF.

Ginsenoside Rg1 Nanoparticles Induce Demethylation of H3K27me3 in VEGF-A and Jagged 1 Promoter Regions to Activate Angiogenesis After Ischemic Stroke

BACKGROUND

Compared with traditional drugs, nanomaterial drugs have the benefits of improving the solubility, bioavailability, and absorption rate of insoluble drugs. Nanoporous complexes can increase the efficiency with which drugs can penetrate the blood-brain barrier and reach target organs. Ginsenoside Rg1 is an effective drug that promotes angiogenesis. Ginsenoside Rg1 composite nanoparticles were employed to induce the expression of several key epigenetic enzymes and then activate the VEGF and Notch pathways after the onset of ischemic brain lesions.

METHODS

We constructed nanoparticles to fully encapsulate the therapeutic drug (ginsenoside Rg1), which can be transferred into brain tissue via the receptor-mediated transfer of drug-encapsulated nanoparticles. Evaluation of the therapeutic effect of ginsenoside Rg1 complex nanovesicles (CNV) was performed by in vitro and in vivo experiments. Real-time polymerase chain reaction (RT- PCR), Western blot, immunohistochemistry staining (IHC), and Co-immunoprecipitation (co-IP) were employed to screen for epigenetic enzymes with an up-regulated expression post ginsenoside Rg1-CNV intervention. RNA sequencing, shRNA knockdown, and chromatin Immunoprecipitation (ChIP) sequencing were performed to detect the target genes of ginsenoside Rg1-CNV that regulate angiogenesis. Then, bioinformatic analysis was performed to investigate the mechanism of action of epigenetic modifying enzymes in regulating target genes.

RESULTS

The average of the synthesized ginsenoside Rg1-CNV was 203.78±6.83 nm, the polydispersion index was 0.135±0.007, and the Zeta potential was 23.13±1.65 mV. Through in vivo and in vitro experiments, we found that it promotes the proliferation, migration, and tubular formation of brain microvascular endothelial cells (BMECs). Meanwhile, the intervention of ginsenoside Rg1-CNV promoted the demethylation of H3K27me3 within the promoter region of VEGF-A and Jagged1 genes and reduced the H3K27me3 modification within this region.

CONCLUSION

The ginsenoside Rg1 nanoparticles may be an available blood-brain barrier penetrating agent for ischemic stroke.

SYK coordinates neuroprotective microglial responses in neurodegenerative disease

Recent studies have begun to reveal critical roles for the brain's professional phagocytes, microglia, and their receptors in the control of neurotoxic amyloid beta (Aβ) and myelin debris accumulation in neurodegenerative disease. However, the critical intracellular molecules that orchestrate neuroprotective functions of microglia remain poorly understood. In our studies, we find that targeted deletion of SYK in microglia leads to exacerbated Aβ deposition, aggravated neuropathology, and cognitive defects in the 5xFAD mouse model of Alzheimer's disease (AD). Disruption of SYK signaling in this AD model was further shown to impede the development of disease-associated microglia (DAM), alter AKT/GSK3β-signaling, and restrict Aβ phagocytosis by microglia. Conversely, receptor-mediated activation of SYK limits Aβ load. We also found that SYK critically regulates microglial phagocytosis and DAM acquisition in demyelinating disease. Collectively, these results broaden our understanding of the key innate immune signaling molecules that instruct beneficial microglial functions in response to neurotoxic material.

Inhibition of Dectin-1 Alleviates Neuroinflammatory Injury by Attenuating NLRP3 Inflammasome-Mediated Pyroptosis After Intracerebral Hemorrhage in Mice: Preliminary Study Results

BACKGROUND

Neuroinflammation plays an important role following intracerebral hemorrhage (ICH). NLRP3 inflammasome-mediated pyroptosis contributes to the mechanism of neuroinflammation. It has been reported that dendritic cell-associated C-type lectin-1 (Dectin-1) activation triggers inflammation in neurological diseases. However, the role of Dectin-1 on NLRP3 inflammasome-mediated pyroptosis after ICH remains unclear. Here, we aimed to explore the effect of Dectin-1 on NLRP3 inflammasome-mediated pyroptosis and neuroinflammation after ICH.

METHODS

Adult male C57BL/6 mice were used to establish the ICH model. Laminarin, an inhibitor of Dectin-1, was administered for intervention. Expression of Dectin-1 was evaluated by Western blot and immunofluorescence. Brain water content and neurobehavioral function were tested to assess brain edema and neurological performance. Western blot was conducted to evaluate the level of GSDMD-N. ELISA kits were used to measure the levels of IL-1β and IL-18. qRT-PCR and Western blot were performed to evaluate the expressions of NLRP3 inflammasome, IL-1β, and IL-18.

RESULTS

The expression of Dectin-1 increased following ICH, and Dectin-1 was expressed on microglia. In addition, inhibition of Dectin-1 by laminarin decreased brain edema and neurological impairment after ICH. Moreover, inhibition of Dectin-1 decreased the expression of pyroptosis-related protein, GSDMD-N, and inflammatory cytokines (IL-1β and IL-18). Mechanistically, Dectin-1 blockade inhibits NLRP3 inflammasome activation, thereby alleviating neuroinflammatory injury by attenuating NLRP3 inflammasome-mediated pyroptosis both in vivo and in vitro.

CONCLUSION

Our study indicates that the inhibition of Dectin-1 alleviates neuroinflammation by attenuating NLRP3 inflammasome-mediated pyroptosis after ICH.

Histones of Neutrophil Extracellular Traps Induce CD11b Expression in Brain Pericytes Via Dectin-1 after Traumatic Brain Injury

The brain pericyte is a unique and indispensable part of the blood-brain barrier (BBB), and contributes to several pathological processes in traumatic brain injury (TBI). However, the cellular and molecular mechanisms by which pericytes are regulated in the damaged brain are largely unknown. Here, we show that the formation of neutrophil extracellular traps (NETs) induces the appearance of CD11b+ pericytes after TBI. These CD11b+ pericyte subsets are characterized by increased permeability and pro-inflammatory profiles compared to CD11b- pericytes. Moreover, histones from NETs by Dectin-1 facilitate CD11b induction in brain pericytes in PKC-c-Jun dependent manner, resulting in neuroinflammation and BBB dysfunction after TBI. These data indicate that neutrophil-NET-pericyte and histone-Dectin-1-CD11b are possible mechanisms for the activation and dysfunction of pericytes. Targeting NETs formation and Dectin-1 are promising means of treating TBI.

Molecular mechanisms for the prevention and promoting the recovery from ischemic stroke by nutraceutical laminarin: A comparative transcriptomic approach

Stroke is the second leading cause of death and a major cause of disability worldwide. Ischemic stroke caused by atherosclerosis accounts for approximately 87% of all stroke cases. Ischemic stroke is a preventable disease; therefore, a better understanding of the molecular mechanisms underlying its pathogenesis and recovery processes could provide therapeutic targets for drug development and reduce the associated mortality rate. Laminarin, a polysaccharide, is a nutraceutical that can be found in brown algae. Accumulating evidence suggests that laminarin could reduce the detrimental effects of neuroinflammation on brain damage after stroke. However, the molecular mechanism underlying its beneficial effects remains largely unknown. In the present study, we used a middle cerebral artery occlusion (MCAO) rat model and applied comparative transcriptomics to investigate the molecular targets and pathways involved in the beneficial effects of laminarin on ischemic stroke. Our results show the involvement of laminarin targets in biological processes related to blood circulation, oxygen supply, and anti-inflammatory responses in the normal brain. More importantly, laminarin treatment attenuated brain damage and neurodeficits caused by ischemic stroke. These beneficial effects are controlled by biological processes related to blood vessel development and brain cell death through the regulation of canonical pathways. Our study, for the first time, delineated the molecular mechanisms underlying the beneficial effects of laminarin on ischemic stroke prevention and recovery and provides novel therapeutic targets for drug development against ischemic stroke.

Markers of fungal translocation are elevated during post-acute sequelae of SARS-CoV-2 and induce NF-κB signaling

Long COVID, a type of post-acute sequelae of SARS-CoV-2 (PASC), has been associated with sustained elevated levels of immune activation and inflammation. However, the mechanisms that drive this inflammation remain unknown. Inflammation during acute coronavirus disease 2019 could be exacerbated by microbial translocation (from the gut and/or lung) to blood. Whether microbial translocation contributes to inflammation during PASC is unknown. We did not observe a significant elevation in plasma markers of bacterial translocation during PASC. However, we observed higher levels of fungal translocation - measured as β-glucan, a fungal cell wall polysaccharide - in the plasma of individuals experiencing PASC compared with those without PASC or SARS-CoV-2-negative controls. The higher β-glucan correlated with higher inflammation and elevated levels of host metabolites involved in activating N-methyl-d-aspartate receptors (such as metabolites within the tryptophan catabolism pathway) with established neurotoxic properties. Mechanistically, β-glucan can directly induce inflammation by binding to myeloid cells (via Dectin-1) and activating Syk/NF-κB signaling. Using a Dectin-1/NF-κB reporter model, we found that plasma from individuals experiencing PASC induced higher NF-κB signaling compared with plasma from negative controls. This higher NF-κB signaling was abrogated by piceatannol (Syk inhibitor). These data suggest a potential targetable mechanism linking fungal translocation and inflammation during PASC.

Role of Dectin-1 in peripheral nerve injury

Dectin-1, a C-type lectin receptor, plays a role in nerve injury in the central nervous system. However, whether it plays a role in the peripheral nervous system is not well understood. Our study showed the expression of Dectin-1 on the membrane of macrophages. We also used a sciatic nerve crushing injury model to demonstrate that there was a delay in nerve degeneration-related processes such as breakdown of injured myelinated nerve fibers and formation of myelin ovoid in groups injected with whole glucan particle soluble (WGPS), a Dectin-1 antagonist. There were also fewer intraneural blood vessels in the Dectin-1 antagonist treated group. Our study suggested inhibiting Dectin-1 delayed debris clearance, nerve degeneration, and angiogenesis after peripheral nerve injury.