Sodium tanshinone IIA sulfonate suppresses microglia polarization and neuroinflammation possibly via regulating miR-125b-5p/STAT3 axis to ameliorate neuropathic pain

The spinal cord microglia play a pivotal role in neuroinflammation and neuropathic pain (NP). Sodium tanshinone IIA sulfonate (STS), a derivative of tanshinone IIA, has anti-inflammatory and anti-hyperalgesic effects. However, its underlying mechanism in NP remains unclear. This study aimed to investigate the effect of STS and elucidate possible mechanisms in a rat model of spared nerve injury. In vivo experiments, STS and AG490 were administered intraperitoneally once daily for 14 consecutive days after surgery. The results showed that the expression of miR-125b-5p in the spinal dorsal horn was substantially reduced, whereas signal transducer and activator of transcription 3 (STAT3) signaling was increased. After treatment with STS, the mechanical thresholds, expression of miR-125b-5p, and microglial M2 marker such as Arg-1 in the spinal cord horn increased significantly, whereas multiple pro-inflammatory cytokines and apoptosis were significantly reduced. Moreover, STAT3 pathway-related proteins and expression of the microglial M1 marker, CD68, were appreciably inhibited. In vitro, lipopolysaccharide (LPS) was used to induce an inflammatory response in BV-2 microglial cells. STS pretreatment inhibited LPS-stimulated pro-inflammatory cytokine secretion, reduced STAT3 pathway related-proteins and apoptosis, increased miR-125b-5p and proopiomelanocortin expression, and enhanced microglia transformation from M1 to M2 phenotype in BV-2 cells. These effects were reversed after the inhibition of miR-125b-5p expression in BV-2 cells. A dual-luciferase reporter assay confirmed that STAT3 binds to miR-125b-5p. In summary, these results suggest that STS exerts anti-hyperalgesic and anti-neuroinflammatory effects in rats with NP possibly via the miR-125b-5p/STAT3 axis.

Effects of novel GLT-1 modulator, MC-100093, on neuroinflammatory and neurotrophic biomarkers in mesocorticolimbic brain regions of male alcohol preferring rats exposed chronically to ethanol

Chronic ethanol consumption can lead to increased extracellular glutamate concentrations in key reward brain regions, such as medial prefrontal cortex (mPFC) and nucleus accumbens (NAc), and consequently leading to oxidative stress and neuroinflammation. Previous studies from our lab tested β-lactam antibiotics and novel beta-lactam non-antibiotic, MC-100093, and showed these β-lactam upregulated the major astrocytic glutamate transporter, GLT-1, and consequently reduced ethanol intake and normalized glutamate homeostasis. This present study tested the effects of novel synthetic β-lactam non-antibiotic drug, MC-100093, in chronic ethanol intake and neuroinflammatory and trophic factors in subregions of the NAc (NAc core and shell) and mPFC (Prelimbic, PL; and Infralimbic, IL) of male P rats. MC-100093 treatment reduced ethanol intake after 5-week drinking regimen. Importantly, MC-100093 attenuated ethanol-induced downregulation of brain derived neurotrophic factor (BDNF) expression in these brain regions. In addition, MC-100093 attenuated ethanol-induced upregulation of pro-inflammatory cytokines such as TNF-a and HMGB1 in all these brain regions. Furthermore, MC-100093 treatment attenuated ethanol-induced increase in RAGE in these brain regions. MC-100093 prevented neuroinflammation caused by ethanol intake as well as increased neurotrophic factor in mesocorticolimbic brain regions. MC-100093 treatment reduced ethanol intake and this behavioral effect was associated with attenuation of reduced trophic factors and increased pro-inflammatory factors. MC-100093 is considered a small molecule that may have potential therapeutic effects for the treatment of the effects of chronic exposure to ethanol.

Mitochondrial metabolism and neuroinflammation in the cerebral cortex and cortical synapses of rats: effect of milk intake through DNA methylation

Brain plasticity and cognitive functions are tightly influenced by foods or nutrients, which determine a metabolic modulation having a long-term effect on health, involving also epigenetic mechanisms. Breast milk or formula based on cow milk is the first food for human beings, who, throughout their lives, are then exposed to different types of milk. We previously demonstrated that rats fed with milk derived from distinct species, with different compositions and nutritional properties, display selective modulation of systemic metabolic and inflammatory profiles through changes of mitochondrial functions and redox state in liver, skeletal and cardiac muscle. Here, in a rat model, we demonstrated that isoenergetic supplementation of milk from cow (CM), donkey (DM) or human (HM) impacts mitochondrial functions and redox state in the brain cortex and cortical synapses, affecting neuroinflammation and synaptic plasticity. Interestingly, we found that the administration of different milk modulates DNA methylation in rat brain cortex and consequently affects gene expression. Our results emphasize the importance of nutrition in brain and synapse physiology, and highlight the key role played in this context by mitochondria, nutrient-sensitive organelles able to orchestrate metabolic and inflammatory responses.

A TNF-α inhibitor abolishes sepsis-induced cognitive impairment in mice by modulating acetylcholine and nitric oxide homeostasis, BDNF release, and neuroinflammation

Neurodegenerative disorders have a pathophysiology that heavily involves neuroinflammation. In this study, we used lipopolysaccharide (LPS) to create a model of cognitive impairment by inducing systemic and neuroinflammation in experimental animals. LPS was injected intraperitoneally at a dose of 0.5 mg/kg during the last seven days of the study. Adalimumab (ADA), a TNF-α inhibitor, was injected at a dose of 10 mg/kg a total of 3 times throughout the study. On the last two days of the experiment, 50 mg/kg of curcumin was administered orally as a positive control group. Open field (OF) and elevated plus maze tests (EPM) were used to measure anxiety-like behaviors. The tail suspension test (TST) was used to measure depression-like behaviors, while the novel object recognition test (NOR) was used to measure learning and memory activities. Blood and hippocampal TNF α and nitric oxide (NO) levels, hippocampal BDNF, CREB, and ACh levels, and AChE activity were measured by ELISA. LPS increased anxiety and depression-like behaviors while decreasing the activity of the learning-memory system. LPS exerted this effect by causing systemic and neuroinflammation, cholinergic dysfunction, and impaired BDNF release. ADA controlled LPS-induced behavioral changes and improved biochemical markers. ADA prevented cognitive impairment induced by LPS by inhibiting inflammation and regulating the release of BDNF and the cholinergic pathway.

mTOR and neuroinflammation in epilepsy: implications for disease progression and treatment

Epilepsy remains a major health concern as anti-seizure medications frequently fail, and there is currently no treatment to stop or prevent epileptogenesis, the process underlying the onset and progression of epilepsy. The identification of the pathological processes underlying epileptogenesis is instrumental to the development of drugs that may prevent the generation of seizures or control pharmaco-resistant seizures, which affect about 30% of patients. mTOR signalling and neuroinflammation have been recognized as critical pathways that are activated in brain cells in epilepsy. They represent a potential node of biological convergence in structural epilepsies with either a genetic or an acquired aetiology. Interventional studies in animal models and clinical studies give strong support to the involvement of each pathway in epilepsy. In this Review, we focus on available knowledge about the pathophysiological features of mTOR signalling and the neuroinflammatory brain response, and their interactions, in epilepsy. We discuss mitigation strategies for each pathway that display therapeutic effects in experimental and clinical epilepsy. A deeper understanding of these interconnected molecular cascades could enhance our strategies for managing epilepsy. This could pave the way for new treatments to fill the gaps in the development of preventative or disease-modifying drugs, thus overcoming the limitations of current symptomatic medications.

Acupuncture Ameliorates Depression-Like Behaviors Through Modulating the Neuroinflammation Mediated by TLR4 Signaling Pathway in Rats Exposed to Chronic Restraint Stress

Recently, emerging evidence has identified that stress-induced activation of neuroinflammation is considered to be one of the most prevalently precipitating factors in the pathogenesis of depression. Data from clinical trials and experimental findings has verified the efficacy and safety of acupuncture in the prevention and treatment of depression. However, the mechanism of the preventive effect of acupuncture for depression has not been fully elucidated. The current study aimed to investigate the preventive effect and mechanism of acupuncture through modulating the neuroinflammation mediated by toll-like receptor 4 (TLR4) signaling pathway in rats exposed to chronic restraint stress (CRS). All rats were subjected to CRS for 21 days, with the exception of rats in control group. One hour before CRS, rats in acupuncture group were exposed to acupuncture at Baihui (GV20) and Yintang (GV29). The depression-like behaviors were evaluated by body weight assessment and sucrose preference test at 0, 7, 14, and 21 days. The expression of activated microglia in hippocampus was detected by immunofluorescence. The expression of key proteins on TLR4 signaling pathway of TLR4, MyD88, TRAF6, NF-κB p65, TNF-α, and mRNA of TLR4 in the hippocampus was detected by western blot and real-time quantitative polymerase chain reaction to investigate the effect of acupuncture on stress-induced activation of neuroinflammation. The present study provided evidence that acupuncture exerted potential preventive effect that might be mediated in part by suppressing the neuroinflammation induced by TLR4 signaling pathway, which may be a promising treatment target to improve current treatments for depression.

Sigma-1 Receptor Inhibition Reduces Mechanical Allodynia and Modulate Neuroinflammation in Chronic Neuropathic Pain

Neuropathic pain is one of the most debilitating forms of chronic pain, resulting from an injury or disease of the somatosensory nervous system, which induces abnormal painful sensations including allodynia and hyperalgesia. Available treatments are limited by severe side-effects and reduced efficacy in the chronic phase of the disease. Sigma-1 receptor (σ1R) has been identified as a chaperone protein, which modulate opioid receptors activities and the functioning of several ion channels, exerting a role in pain transmission. As such, it represents a druggable target to treat neuropathic pain. This study aims at investigating the therapeutic potential of the novel compound (+)-2R/S-LP2, a σ1R antagonist, in reducing painful behaviour and modulating the neuroinflammatory environment. We showed that repeated administration of the compound significantly inhibited mechanical allodynia in neuropathic rats, increasing the withdrawal threshold as compared to CCI-vehicle rats. Moreover, we found that (+)-2R/S-LP2-mediated effects resolve the neuroinflammatory microenvironment by reducing central gliosis and pro-inflammatory cytokines expression levels. This effect was coupled with a significant reduction of connexin 43 (Cx43) expression levels and gap junctions/hemichannels mediated microglia-to-astrocyte communication. These results suggest that inhibition of σ1R significantly attenuates neuropathic pain chronicization, thus representing a viable effective strategy.

Effect of CTLA-4 Inhibition on Inflammation and Apoptosis After Spinal Cord Injury

Spinal cord injury (SCI) encompasses various pathological processes, notably neuroinflammation and apoptosis, both of which play significant roles. CTLA-4, a well-known immune molecule that suppresses T cell-mediated immune responses, is a key area of research and a focal point for targeted therapy development in treating tumors and autoimmune disorders. Despite its prominence, the impact of CTLA-4 inhibition on inflammation and apoptosis subsequent to SCI remains unexplored. This study aimed to investigate the influence of CTLA-4 on SCI. A weight-drop technique was used to establish a rat model of SCI. To examine the safeguarding effect of CTLA-4 on the restoration of motor function in rats with SCI, the Basso-Beattie-Bresnahan (BBB) scale and inclined plane test were employed to assess locomotion. Neuronal degeneration and apoptosis were assessed using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling (TUNEL) and Fluoro-Jade B labeling, respectively, and the activity of microglial cells was examined by immunofluorescence. To evaluate the impact of CTLA4 on SCI, the levels of inflammatory markers were measured. After treatment with the CTLA-4 inhibitor ipilimumab, the rats showed worse neurological impairment and more severe neuroinflammation after SCI. Furthermore, the combination therapy with ipilimumab and durvalumab after SCI had more pronounced effects than treatment with either inhibitor alone. These findings indicate that CTLA-4 contributes to neuroinflammation and apoptosis after SCI, presenting a promising new therapeutic target for this traumatic condition.

Increased levels and activation of the IL-17 receptor in microglia contribute to enhanced neuroinflammation in cerebellum of hyperammonemic rats

BACKGROUND

Patients with liver cirrhosis may show minimal hepatic encephalopathy (MHE) with mild cognitive impairment and motor incoordination. Rats with chronic hyperammonemia reproduce these alterations. Motor incoordination in hyperammonemic rats is due to increased GABAergic neurotransmission in cerebellum, induced by neuroinflammation, which enhances TNFα-TNFR1-S1PR2-CCL2-BDNF-TrkB pathway activation. The initial events by which hyperammonemia triggers activation of this pathway remain unclear. MHE in cirrhotic patients is triggered by a shift in inflammation with increased IL-17. The aims of this work were: (1) assess if hyperammonemia increases IL-17 content and membrane expression of its receptor in cerebellum of hyperammonemic rats; (2) identify the cell types in which IL-17 receptor is expressed and IL-17 increases in hyperammonemia; (3) assess if blocking IL-17 signaling with anti-IL-17 ex-vivo reverses activation of glia and of the TNFα-TNFR1-S1PR2-CCL2-BDNF-TrkB pathway.

RESULTS

IL-17 levels and membrane expression of the IL-17 receptor are increased in cerebellum of rats with hyperammonemia and MHE, leading to increased activation of IL-17 receptor in microglia, which triggers activation of STAT3 and NF-kB, increasing IL-17 and TNFα levels, respectively. TNFα released from microglia activates TNFR1 in Purkinje neurons, leading to activation of NF-kB and increased IL-17 and TNFα also in these cells. Enhanced TNFR1 activation also enhances activation of the TNFR1-S1PR2-CCL2-BDNF-TrkB pathway which mediates microglia and astrocytes activation.

CONCLUSIONS

All these steps are triggered by enhanced activation of IL-17 receptor in microglia and are prevented by ex-vivo treatment with anti-IL-17. IL-17 and IL-17 receptor in microglia would be therapeutic targets to treat neurological impairment in patients with MHE.

Neuroinflammation driven by human immunodeficiency virus-1 (HIV-1) directs the expression of long noncoding RNA RP11-677M14.2 resulting in dysregulation of neurogranin in vivo and in vitro

Neuroinflammation and synaptodendritic damage represent the pathological hallmarks of HIV-1 associated cognitive disorders (HAND). The post-synaptic protein neurogranin (Nrgn) is significantly reduced in the frontal cortex of postmortem brains from people with HIV (PWH) and it is associated with inflammatory factors released by infected microglia/macrophages. However, the mechanism involved in synaptic loss have yet to be elucidated. In this study, we characterized a newly identified long non-coding RNA (lncRNA) transcript (RP11-677M14.2), which is antisense to the NRGN locus and is highly expressed in the frontal cortex of HIV-1 individuals. Further analysis indicates an inverse correlation between the expression of RP11-677M14.2 RNA and Nrgn mRNA. Additionally, the Nrgn-lncRNA axis is dysregulated in neurons exposed to HIV-1 infected microglia conditioned medium enriched with IL-1β. Moreover, in vitro overexpression of this lncRNA impacts Nrgn expression at both mRNA and protein levels. Finally, we modeled the Nrgn-lncRNA dysregulation within an HIV-1-induced inflammatory environment using brain organoids, thereby corroborating our in vivo and in vitro findings. Together, our study implicates a plausible role for lncRNA RP11-677M14.2 in modulating Nrgn expression that might serve as the mechanistic link between Nrgn loss and cognitive dysfunction in HAND, thus shedding new light on the mechanisms underlying synaptodendritic damage.

Sex Dimorphism in Pain Threshold and Neuroinflammatory Response: The Protective Effect of Female Sexual Hormones on Behavior and Seizures in an Allergic Rhinitis Model

Our previous research demonstrated that allergic rhinitis could impact behavior and seizure threshold in male mice. However, due to the complex hormonal cycles and hormonal influences on behavior in female mice, male mice are more commonly used for behavioral tests. In this study, we aimed to determine whether these findings were replicable in female mice and to explore the potential involvement of sexual hormones in regulating neuroinflammation in an allergic model. Our results indicate that pain threshold was decreased in female mice with allergic rhinitis and the levels of IL-23/IL-17A/IL-17R were increased in their Dorsal root ganglia. However, unlike males, female mice with AR did not display neuropsychological symptoms such as learning and memory deficits, depression, and anxiety-like behavior. This was along with decreased levels of DNA methyl transferase 1 (DNMT1) and inflammatory cytokines in their hippocampus. Ovariectomized mice were used to mitigate hormonal effects, and the results showed that they had behavioral changes and neuroinflammation in their hippocampus similar to male mice, as well as increased levels of DNMT1. These findings demonstrate sex differences in how allergic rhinitis affects behavior, pain sensitivity, and seizure thresholds. Furthermore, our data suggest that DNMT1 may be influenced by sexual hormones, which could play a role in modulating inflammation in allergic conditions.

Matrilin-3 supports neuroprotection in ischemic stroke by suppressing astrocyte-mediated neuroinflammation

In the brain, the role of matrilin-3, an extracellular matrix component in cartilage, is unknown. Here, we identify that matrilin-3 decreased in reactive astrocytes but was unchanged in neurons after ischemic stroke in animals. Importantly, it declined in serum of patients with acute ischemic stroke. Genetic or pharmacological inhibition or supplementation of matrilin-3 aggravates or reduces brain injury, astrocytic cell death, and glial scar, respectively, but has no direct effect on neuronal cell death. RNA sequencing demonstrates that Matn3-/- mice display an increased inflammatory response profile in the ischemic brain, including the nuclear factor κB (NF-κB) signaling pathway. Both endogenous and exogenous matrilin-3 reduce inflammatory mediators. Mechanistically, extracellular matrilin-3 enters astrocytes via caveolin-1-mediated endocytosis. Cytoplasmic matrilin-3 translocates into the nucleus by binding to NF-κB p65, suppressing inflammatory cytokine transcription. Extracellular matrilin-3 binds to BMP-2, blocking the BMP-2/Smads pathway. Thus, matrilin-3 is required for astrocytes to exert neuroprotection, at least partially, by suppressing astrocyte-mediated neuroinflammation.

Pathological high intraocular pressure induces glial cell reactive proliferation contributing to neuroinflammation of the blood-retinal barrier via the NOX2/ET-1 axis-controlled ERK1/2 pathway

BACKGROUND

NADPH oxidase (NOX), a primary source of endothelial reactive oxygen species (ROS), is considered a key event in disrupting the integrity of the blood-retinal barrier. Abnormalities in neurovascular-coupled immune signaling herald the loss of ganglion cells in glaucoma. Persistent microglia-driven inflammation and cellular innate immune system dysregulation often lead to deteriorating retinal degeneration. However, the crosstalk between NOX and the retinal immune environment remains unresolved. Here, we investigate the interaction between oxidative stress and neuroinflammation in glaucoma by genetic defects of NOX2 or its regulation via gp91ds-tat.

METHODS

Ex vivo cultures of retinal explants from wildtype C57BL/6J and Nox2 -/- mice were subjected to normal and high hydrostatic pressure (Pressure 60 mmHg) for 24 h. In vivo, high intraocular pressure (H-IOP) was induced in C57BL/6J mice for two weeks. Both Pressure 60 mmHg retinas and H-IOP mice were treated with either gp91ds-tat (a NOX2-specific inhibitor). Proteomic analysis was performed on control, H-IOP, and treatment with gp91ds-tat retinas to identify differentially expressed proteins (DEPs). The study also evaluated various glaucoma phenotypes, including IOP, retinal ganglion cell (RGC) functionality, and optic nerve (ON) degeneration. The superoxide (O2-) levels assay, blood-retinal barrier degradation, gliosis, neuroinflammation, enzyme-linked immunosorbent assay (ELISA), western blotting, and quantitative PCR were performed in this study.

RESULTS

We found that NOX2-specific deletion or activity inhibition effectively attenuated retinal oxidative stress, immune dysregulation, the internal blood-retinal barrier (iBRB) injury, neurovascular unit (NVU) dysfunction, RGC loss, and ON axonal degeneration following H-IOP. Mechanistically, we unveiled for the first time that NOX2-dependent ROS-driven pro-inflammatory signaling, where NOX2/ROS induces endothelium-derived endothelin-1 (ET-1) overexpression, which activates the ERK1/2 signaling pathway and mediates the shift of microglia activation to a pro-inflammatory M1 phenotype, thereby triggering a neuroinflammatory outburst.

CONCLUSIONS

Collectively, we demonstrate for the first time that NOX2 deletion or gp91ds-tat inhibition attenuates iBRB injury and NVU dysfunction to rescue glaucomatous RGC loss and ON axon degeneration, which is associated with inhibition of the ET-1/ERK1/2-transduced shift of microglial cell activation toward a pro-inflammatory M1 phenotype, highlighting NOX2 as a potential target for novel neuroprotective therapies in glaucoma management.

Itaconate alleviates anesthesia/surgery-induced cognitive impairment by activating a Nrf2-dependent anti-neuroinflammation and neurogenesis via gut-brain axis

BACKGROUND

Postoperative cognitive dysfunction (POCD) is a common neurological complication of anesthesia and surgery in aging individuals. Neuroinflammation has been identified as a hallmark of POCD. However, safe and effective treatments of POCD are still lacking. Itaconate is an immunoregulatory metabolite derived from the tricarboxylic acid cycle that exerts anti-inflammatory effects by activating the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway. In this study, we investigated the effects and underlying mechanism of 4-octyl itaconate (OI), a cell-permeable itaconate derivative, on POCD in aged mice.

METHODS

A POCD animal model was established by performing aseptic laparotomy in 18-month-old male C57BL/6 mice under isoflurane anesthesia while maintaining spontaneous ventilation. OI was intraperitoneally injected into the mice after surgery. Primary microglia and neurons were isolated and treated to lipopolysaccharide (LPS), isoflurane, and OI. Cognitive function, neuroinflammatory responses, as well as levels of gut microbiota and their metabolites were evaluated. To determine the mechanisms underlying the therapeutic effects of OI in POCD, ML385, an antagonist of Nrf2, was administered intraperitoneally. Cognitive function, neuroinflammatory responses, endogenous neurogenesis, neuronal apoptosis, and Nrf2/extracellular signal-related kinases (ERK) signaling pathway were evaluated.

RESULTS

Our findings revealed that OI treatment significantly alleviated anesthesia/surgery-induced cognitive impairment, concomitant with reduced levels of the neuroinflammatory cytokines IL-1β and IL-6, as well as suppressed activation of microglia and astrocytes in the hippocampus. Similarly, OI treatment inhibited the expression of IL-1β and IL-6 in LPS and isoflurane-induced primary microglia in vitro. Intraperitoneal administration of OI led to alterations in the gut microbiota and promoted the production of microbiota-derived metabolites associated with neurogenesis. We further confirmed that OI promoted endogenous neurogenesis and inhibited neuronal apoptosis in the hippocampal dentate gyrus of aged mice. Mechanistically, we observed a decrease in Nrf2 expression in hippocampal neurons both in vitro and in vivo, which was reversed by OI treatment. We found that Nrf2 was required for OI treatment to inhibit neuroinflammation in POCD. The enhanced POCD recovery and promotion of neurogenesis triggered by OI exposure were, at least partially, mediated by the activation of the Nrf2/ERK signaling pathway.

CONCLUSIONS

Our findings demonstrate that OI can attenuate anesthesia/surgery-induced cognitive impairment by stabilizing the gut microbiota and activating Nrf2 signaling to restrict neuroinflammation and promote neurogenesis. Boosting endogenous itaconate or supplementation with exogenous itaconate derivatives may represent novel strategies for the treatment of POCD.

Anti-Neuroinflammatory Effects of a Macrocyclic Peptide-Peptoid Hybrid in Lipopolysaccharide-Stimulated BV2 Microglial Cells

Inflammation processes of the central nervous system (CNS) play a vital role in the pathogenesis of several neurological and psychiatric disorders like depression. These processes are characterized by the activation of glia cells, such as microglia. Clinical studies showed a decrease in symptoms associated with the mentioned diseases after the treatment with anti-inflammatory drugs. Therefore, the investigation of novel anti-inflammatory drugs could hold substantial potential in the treatment of disorders with a neuroinflammatory background. In this in vitro study, we report the anti-inflammatory effects of a novel hexacyclic peptide-peptoid hybrid in lipopolysaccharide (LPS)-stimulated BV2 microglial cells. The macrocyclic compound X15856 significantly suppressed Interleukin 6 (IL-6), tumor necrosis factor-α (TNF-α), c-c motif chemokine ligand 2 (CCL2), CCL3, C-X-C motif chemokine ligand 2 (CXCL2), and CXCL10 expression and release in LPS-treated BV2 microglial cells. The anti-inflammatory effects of the compound are partially explained by the modulation of the phosphorylation of p38 mitogen-activated protein kinases (MAPK), p42/44 MAPK (ERK 1/2), protein kinase C (PKC), and the nuclear factor (NF)-κB, respectively. Due to its remarkable anti-inflammatory properties, this compound emerges as an encouraging option for additional research and potential utilization in disorders influenced by inflammation, such as depression.

Prophylactic Administration of Gut Microbiome Metabolites Abrogated Microglial Activation and Subsequent Neuroinflammation in an Experimental Model of Japanese Encephalitis

Short-chain fatty acids (SCFAs) are gut microbial metabolic derivatives produced during the fermentation of ingested complex carbohydrates. SCFAs have been widely regarded to have a potent anti-inflammatory and neuro-protective role and have implications in several disease conditions, such as, inflammatory bowel disease, type-2 diabetes, and neurodegenerative disorders. Japanese encephalitis virus (JEV), a neurotropic flavivirus, is associated with life threatening neuro-inflammation and neurological sequelae in infected hosts. In this study, we hypothesize that SCFAs have potential in mitigating JEV pathogenesis. Postnatal day 10 BALB/c mice were intraperitoneally injected with either a SCFA mixture (acetate, propionate, and butyrate) or PBS for a period of 7 days, followed by JEV infection. All mice were observed for onset and progression of symptoms. The brain tissue was collected upon reaching terminal illness for further analysis. SCFA-supplemented JEV-infected mice (SCFA + JEV) showed a delayed onset of symptoms, lower hindlimb clasping score, and decreased weight loss and increased survival by 3 days (p < 0.0001) upon infection as opposed to the PBS-treated JEV-infected animals (JEV). Significant downregulation of inflammatory cytokines TNF-α, MCP-1, IL-6, and IFN-Υ in the SCFA + JEV group relative to the JEV-infected control group was observed. Inflammatory mediators, phospho-NF-kB (P-NF-kB) and iba1, showed 2.08 ± 0.1 and 3.132 ± 0.43-fold upregulation in JEV versus 1.19 ± 0.11 and 1.31 ± 0.11-fold in the SCFA + JEV group, respectively. Tissue section analysis exhibited reduced glial activation (JEV group─42 ± 2.15 microglia/ROI; SCFA + JEV group─27.07 ± 1.8 microglia/ROI) in animals that received SCFA supplementation prior to infection as seen from the astrocytic and microglial morphometric analysis. Caspase-3 immunoblotting showed 4.08 ± 1.3-fold upregulation in JEV as compared to 1.03 ± 0.14-fold in the SCFA + JEV group and TUNEL assay showed a reduced cellular death post-JEV infection (JEV-6.4 ± 1.5 cells/ROI and SCFA + JEV-3.7 ± 0.73 cells/ROI). Our study critically contributes to the increasing evidence in support of SCFAs as an anti-inflammatory and neuro-protective agent, we further expand its scope as a potential supplementary intervention in JEV-mediated neuroinflammation.

Novel Findings on CCR1 Receptor in CNS Disorders: A Pathogenic Marker Useful in Controlling Neuroimmune and Neuroinflammatory Mechanisms in Parkinson's Disease

Parkinson's disease (PD) is recognized as the second most common neurodegenerative disease worldwide. Even if PD etiopathogenesis is not yet fully understood, in recent years, it has been advanced that a chronic state of inflammation could play a decisive role in the development of this pathology, establishing the close link between PD and neuroinflammation. In the broad panorama of inflammation and its several signaling pathways, the C-C chemokine receptor type 1 (CCR1) could play a key pathogenic role in PD progression, and could constitute a valuable target for the development of innovative anti-PD therapies. In this study, we probed the neuroprotective properties of the CCR1 antagonist BX471 compound in a mouse model of MPTP-induced nigrostriatal degeneration. BX471 treatments were performed intraperitoneally at a dose of 3 mg/kg, 10 mg/kg, and 30 mg/kg, starting 24 h after the last injection of MPTP and continuing for 7 days. From our data, BX471 treatment strongly blocked CCR1 and, as a result, decreased PD features, also reducing the neuroinflammatory state by regulating glial activation, NF-κB pathway, proinflammatory enzymes, and cytokines overexpression. Moreover, we showed that BX471's antagonistic action on CCR1 reduced the infiltration of immune cells, including mast cells and lymphocyte T activation. In addition, biochemical analyses carried out on serum revealed a considerable increase in circulating levels of CCR1 following MPTP-induced PD. In light of these findings, CCR1 could represent a useful pathological marker of PD, and its targeting could be a worthy candidate for the future development of new immunotherapies against PD.

Cellular architecture of evolving neuroinflammatory lesions and multiple sclerosis pathology

Multiple sclerosis (MS) is a neurological disease characterized by multifocal lesions and smoldering pathology. Although single-cell analyses provided insights into cytopathology, evolving cellular processes underlying MS remain poorly understood. We investigated the cellular dynamics of MS by modeling temporal and regional rates of disease progression in mouse experimental autoimmune encephalomyelitis (EAE). By performing single-cell spatial expression profiling using in situ sequencing (ISS), we annotated disease neighborhoods and found centrifugal evolution of active lesions. We demonstrated that disease-associated (DA)-glia arise independently of lesions and are dynamically induced and resolved over the disease course. Single-cell spatial mapping of human archival MS spinal cords confirmed the differential distribution of homeostatic and DA-glia, enabled deconvolution of active and inactive lesions into sub-compartments, and identified new lesion areas. By establishing a spatial resource of mouse and human MS neuropathology at a single-cell resolution, our study unveils the intricate cellular dynamics underlying MS.

Two-Month Voluntary Ethanol Consumption Promotes Mild Neuroinflammation in the Cerebellum but Not in the Prefrontal Cortex, Hippocampus, or Striatum of Mice

Chronic ethanol exposure often triggers neuroinflammation in the brain's reward system, potentially promoting the drive for ethanol consumption. A main marker of neuroinflammation is the microglia-derived monocyte chemoattractant protein 1 (MCP1) in animal models of alcohol use disorder in which ethanol is forcefully given. However, there are conflicting findings on whether MCP1 is elevated when ethanol is taken voluntarily, which challenges its key role in promoting motivation for ethanol consumption. Here, we studied MCP1 mRNA levels in areas implicated in consumption motivation-specifically, the prefrontal cortex, hippocampus, and striatum-as well as in the cerebellum, a brain area highly sensitive to ethanol, of C57BL/6 mice subjected to intermittent and voluntary ethanol consumption for two months. We found a significant increase in MCP1 mRNA levels in the cerebellum of mice that consumed ethanol compared to controls, whereas no significant changes were observed in the prefrontal cortex, hippocampus, or striatum or in microglia isolated from the hippocampus and striatum. To further characterize cerebellar neuroinflammation, we measured the expression changes in other proinflammatory markers and chemokines, revealing a significant increase in the proinflammatory microRNA miR-155. Notably, other classical proinflammatory markers, such as TNFα, IL6, and IL-1β, remained unaltered, suggesting mild neuroinflammation. These results suggest that the onset of neuroinflammation in motivation-related areas is not required for high voluntary consumption in C57BL/6 mice. In addition, cerebellar susceptibility to neuroinflammation may be a trigger to the cerebellar degeneration that occurs after chronic ethanol consumption in humans.

Lack of Direct Effects of Neurotrophic Factors in an In Vitro Model of Neuroinflammation

Neuroinflammation is associated with several neurological disorders including temporal lobe epilepsy. Seizures themselves can induce neuroinflammation. In an in vivo model of epilepsy, the supplementation of brain-derived neurotropic factor (BDNF) and fibroblast growth factor-2 (FGF-2) using a Herpes-based vector reduced epileptogenesis-associated neuroinflammation. The aim of this study was to test whether the attenuation of the neuroinflammation obtained in vivo with BDNF and FGF-2 was direct or secondary to other effects, for example, the reduction in the severity and frequency of spontaneous recurrent seizures. An in vitro model of neuroinflammation induced by lipopolysaccharide (LPS, 100 ng/mL) in a mouse primary mixed glial culture was used. The releases of cytokines and NO were analyzed via ELISA and Griess assay, respectively. The effects of LPS and neurotrophic factors on cell viability were determined by performing an MTT assay. BDNF and FGF-2 were tested alone and co-administered. LPS induced a significant increase in pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) and NO. BDNF, FGF-2, and their co-administration did not counteract these LPS effects. Our study suggests that the anti-inflammatory effect of BDNF and FGF-2 in vivo in the epilepsy model was indirect and likely due to a reduction in seizure frequency and severity.

Mitochondrial complex I activity in microglia sustains neuroinflammation

Sustained smouldering, or low-grade activation, of myeloid cells is a common hallmark of several chronic neurological diseases, including multiple sclerosis1. Distinct metabolic and mitochondrial features guide the activation and the diverse functional states of myeloid cells2. However, how these metabolic features act to perpetuate inflammation of the central nervous system is unclear. Here, using a multiomics approach, we identify a molecular signature that sustains the activation of microglia through mitochondrial complex I activity driving reverse electron transport and the production of reactive oxygen species. Mechanistically, blocking complex I in pro-inflammatory microglia protects the central nervous system against neurotoxic damage and improves functional outcomes in an animal disease model in vivo. Complex I activity in microglia is a potential therapeutic target to foster neuroprotection in chronic inflammatory disorders of the central nervous system3.

Nutritional strategies cause memory damage and alter biochemical parameters without causing neuroinflammation

Obesity results from an energy imbalance and has been considered an epidemic due to its increasing rates worldwide. It is classified as a low-grade chronic inflammatory disease and has associated comorbidities. Different nutritional strategies are used for the purpose of weight loss, highlighting low-carbohydrate (LC) diets, ketogenic diets, and intermittent fasting (IF). These strategies can lead to metabolic and behavioral changes as they stimulate different biochemical pathways. Therefore, this study evaluated memory, energy metabolism, neuroinflammation, oxidative stress, and antioxidant defense parameters in mice subjected to an LC diet, ketogenic diet (KD), or IF. Eighty male Swiss mice, 60 days old, were divided into 4 groups: control, LC, KD, or IF. Body weight was measured weekly, and food intake every 48 h. After 15 days of nutritional interventions, the animals were subjected to the behavioral object recognition test and subsequently euthanized. Then, visceral fat was removed and weighed, and the brain was isolated for inflammatory and biochemical analysis. We concluded from this study that the LC and KD strategies could damage memory, IF improves the production of adenosine triphosphate (ATP), and the LC, KD, and IF strategies do not lead to neuroinflammatory damage but present damage at the level of oxidative stress.

4R-cembranoid suppresses glial cells inflammatory phenotypes and prevents hippocampal neuronal loss in LPS-treated mice

Chronic neuroinflammation has been implicated in neurodegenerative disease pathogenesis. A key feature of neuroinflammation is neuronal loss and glial activation, including microglia and astrocytes. 4R-cembranoid (4R) is a natural compound that inhibits hippocampal pro-inflammatory cytokines and increases memory function in mice. We used the lipopolysaccharide (LPS) injection model to study the effect of 4R on neuronal density and microglia and astrocyte activation. C57BL/6J wild-type mice were injected with LPS (5 mg/kg) and 2 h later received either 4R (6 mg/kg) or vehicle. Mice were sacrificed after 72 h for analysis of brain pathology. Confocal images of brain sections immunostained for microglial, astrocyte, and neuronal markers were used to quantify cellular hippocampal phenotypes and neurons. Hippocampal lysates were used to measure the expression levels of neuronal nuclear protein (NeuN), inducible nitrous oxide synthase (iNOS), arginase-1, thrombospondin-1 (THBS1), glial cell-derived neurotrophic factor (GDNF), and orosomucoid-2 (ORM2) by western blot. iNOS and arginase-1 are widely used protein markers of pro- and anti-inflammatory microglia, respectively. GDNF promotes neuronal survival, and ORM2 and THBS1 are astrocytic proteins that regulate synaptic plasticity and inhibit microglial activation. 4R administration significantly reduced neuronal loss and the number of pro-inflammatory microglia 72 h after LPS injection. It also decreased the expression of the pro-inflammatory protein iNOS while increasing arginase-1 expression, supporting its anti-inflammatory role. The protein expression of THBS1, GDNF, and ORM2 was increased by 4R. Our data show that 4R preserves the integrity of hippocampal neurons against LPS-induced neuroinflammation in mice.

AZD1390, an ataxia telangiectasia mutated inhibitor, attenuates microglia-mediated neuroinflammation and ischemic brain injury

AIMS

Excessive neuroinflammation mediated mainly by microglia plays a crucial role in ischemic stroke. AZD1390, an ataxia telangiectasia mutated (ATM) specific inhibitor, has been shown to promote radio-sensitization and survival in central nervous system malignancies, while the role of AZD1390 in ischemic stroke remains unknown.

METHODS

Real-time PCR, western blot, immunofluorescence staining, flow cytometry and enzyme-linked immunosorbent assays were used to assess the activation of microglia and the release of inflammatory cytokines. Behavioral tests were performed to measure neurological deficits. 2,3,5-Triphenyltetrazolium chloride staining was conducted to assess the infarct volume. The activation of NF-κB signaling pathway was explored through immunofluorescence staining, western blot, co-immunoprecipitation and proximity ligation assay.

RESULTS

The level of pro-inflammation cytokines and activation of NF-κB signaling pathway was suppressed by AZD1390 in vitro and in vivo. The behavior deficits and infarct size were partially restored with AZD1390 treatment in experimental stroke. AZD1390 restrict ubiquitylation and sumoylation of the essential regulatory subunit of NF-κB (NEMO) in an ATM-dependent and ATM-independent way respectively, which reduced the activation of the NF-κB pathway.

CONCLUSION

AZD1390 suppressed NF-κB signaling pathway to alleviate ischemic brain injury in experimental stroke, and attenuated microglia activation and neuroinflammation, which indicated that AZD1390 might be an attractive agent for the treatment of ischemic stroke.

Kdm6a-CNN1 axis orchestrates epigenetic control of trauma-induced spinal cord microvascular endothelial cell senescence to balance neuroinflammation for improved neurological repair

Cellular senescence assumes pivotal roles in various diseases through the secretion of proinflammatory factors. Despite extensive investigations into vascular senescence associated with aging and degenerative diseases, the molecular mechanisms governing microvascular endothelial cell senescence induced by traumatic stress, particularly its involvement in senescence-induced inflammation, remain insufficiently elucidated. In this study, we present a comprehensive demonstration and characterization of microvascular endothelial cell senescence induced by spinal cord injury (SCI). Lysine demethylase 6A (Kdm6a), commonly known as UTX, emerges as a crucial regulator of cell senescence in injured spinal cord microvascular endothelial cells (SCMECs). Upregulation of UTX induces senescence in SCMECs, leading to an amplified release of proinflammatory factors, specifically the senescence-associated secretory phenotype (SASP) components, thereby modulating the inflammatory microenvironment. Conversely, the deletion of UTX in endothelial cells shields SCMECs against senescence, mitigates the release of proinflammatory SASP factors, and promotes neurological functional recovery after SCI. UTX forms an epigenetic regulatory axis by binding to calponin 1 (CNN1), orchestrating trauma-induced SCMECs senescence and SASP secretion, thereby influencing neuroinflammation and neurological functional repair. Furthermore, local delivery of a senolytic drug reduces senescent SCMECs and suppresses proinflammatory SASP secretion, reinstating a local regenerative microenvironment and enhancing functional repair after SCI. In conclusion, targeting the UTX-CNN1 epigenetic axis to prevent trauma-induced SCMECs senescence holds the potential to inhibit SASP secretion, alleviate neuroinflammation, and provide a novel treatment strategy for SCI repair.

SKA2 regulated hyperactive secretory autophagy drives neuroinflammation-induced neurodegeneration

High levels of proinflammatory cytokines induce neurotoxicity and catalyze inflammation-driven neurodegeneration, but the specific release mechanisms from microglia remain elusive. Here we show that secretory autophagy (SA), a non-lytic modality of autophagy for secretion of vesicular cargo, regulates neuroinflammation-mediated neurodegeneration via SKA2 and FKBP5 signaling. SKA2 inhibits SA-dependent IL-1β release by counteracting FKBP5 function. Hippocampal Ska2 knockdown in male mice hyperactivates SA resulting in neuroinflammation, subsequent neurodegeneration and complete hippocampal atrophy within six weeks. The hyperactivation of SA increases IL-1β release, contributing to an inflammatory feed-forward vicious cycle including NLRP3-inflammasome activation and Gasdermin D-mediated neurotoxicity, which ultimately drives neurodegeneration. Results from protein expression and co-immunoprecipitation analyses of male and female postmortem human brains demonstrate that SA is hyperactivated in Alzheimer's disease. Overall, our findings suggest that SKA2-regulated, hyperactive SA facilitates neuroinflammation and is linked to Alzheimer's disease, providing mechanistic insight into the biology of neuroinflammation.

HIPK2 mediates M1 polarization of microglial cells via STAT3: A new mechanism of depression-related neuroinflammation

This study aimed to investigate the role of protein kinase HIPK2 in depression and its associated mechanism. The chronic unpredictable mild stress (CUSM) model was constructed to simulate mice with depression to detect the mouse behaviors. Moreover, by using mouse microglial cells BV2 as the model. After conditional knockdown of HIPK2, the depressive behavior disorder of mice was improved, meanwhile, neuroinflammation was alleviated, and the M1 cell proportion was reduced. Similar results were obtained after applying the HIPK2 inhibitor tBID or ASO-HIPK2 treatment. HIPK2 was overexpressed in BV2 cells, which promoted M1 polarization of cells, while tBID suppressed the effect of HIPK2 and reduced the M1 polarized level in BV2 cells. Pull-down assay results indicated that HIPK2 bound to STAT3 and promoted STAT3 phosphorylation. We found that HIPK2 can bind to STAT3 to promote its phosphorylation, which accelerates M1 polarization of microglial cells, aggravates the depressive neuroinflammation, and leads to abnormal behaviors. HIPK2 is promising as the new therapeutic target of depression.

Dexmedetomidine mitigates neuroinflammation in an Alzheimer's disease mouse model via the miR-204-3p/FBXL7 signaling axis

Alzheimer's disease (AD) is a prevalent neurodegenerative disorder characterized by neuroinflammation. Dexmedetomidine (Dex) is known for its neuroprotective properties in clinical settings. In this study, we investigated the potential of Dex in protecting against neuroinflammation in an AD mouse model induced by amyloid-beta (Aβ) injection. First, in the AD mouse model, Aβ injection were administered, and the model was confirmed through behavioral tests, including the Morris water maze and Y-maze. Neuroinflammatory states in Aβ-injected mice were assessed using hematoxylin and eosin staining and enzyme-linked immunosorbent assay. Expression levels of microRNA (miR)-204-3p and F-box/LRR-repeat protein 7 (FBXL7) in mouse tissues were determined through real-time quantitative polymerase chain reaction and Western blot. The binding interaction between miR-204-3p and FBXL7 was elucidated using dual-luciferase analysis. Aβ-injected mice exhibited cognitive impairment, neuroinflammation, and downregulated miR-204-3p. Upregulation of miR-204-3p reduced inflammatory infiltration and mitigated neuroinflammation in Aβ-injected mice. Dex treatment reduced inflammation in hippocampal tissues of Aβ-injected mice. Dex treatment upregulated miR-204-3p, leading to suppressed FBXL7 expression in tissues. Inhibition of miR-204-3p or overexpression of FBXL7 reversed the alleviating effect of Dex on neuroinflammation in Aβ-injected mice. Overall, Dex increased miR-204-3p expression, resulting in the inhibition of FBXL7, and subsequently alleviated neuroinflammation in Aβ-injected mice.

A20 regulates lymphocyte adhesion in murine neuroinflammation by restricting endothelial ICOSL expression in the CNS

A20 is a ubiquitin-modifying protein that negatively regulates NF-κB signaling. Mutations in A20/TNFAIP3 are associated with a variety of autoimmune diseases, including multiple sclerosis (MS). We found that deletion of A20 in central nervous system (CNS) endothelial cells (ECs) enhances experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. A20ΔCNS-EC mice showed increased numbers of CNS-infiltrating immune cells during neuroinflammation and in the steady state. While the integrity of the blood-brain barrier (BBB) was not impaired, we observed a strong activation of CNS-ECs in these mice, with dramatically increased levels of the adhesion molecules ICAM-1 and VCAM-1. We discovered ICOSL to be expressed by A20-deficient CNS-ECs, which we found to function as adhesion molecules. Silencing of ICOSL in CNS microvascular ECs partly reversed the phenotype of A20ΔCNS-EC mice without reaching statistical significance and delayed the onset of EAE symptoms in WT mice. In addition, blocking of ICOSL on primary mouse brain microvascular ECs impaired the adhesion of T cells in vitro. Taken together, we propose that CNS EC-ICOSL contributes to the firm adhesion of T cells to the BBB, promoting their entry into the CNS and eventually driving neuroinflammation.

Cytomegalovirus antibodies are associated with mood disorders, suicide, markers of neuroinflammation, and microglia activation in postmortem brain samples

Cytomegalovirus (CMV) is a common, neurotrophic herpesvirus that can be reactivated by inflammation and cause central nervous system disease. We hypothesize that CMV may contribute to the neuroinflammation that underlies some psychiatric disorders by (1) exacerbating inflammation through the induction of anti-viral immune responses, and (2) translating peripheral inflammation into neuroinflammation. We investigated whether the presence of anti-CMV antibodies in blood were associated with mental illness, suicide, neuroinflammation, and microglial density in the dorsolateral prefrontal cortex (DLPFC) in postmortem samples. Data (n = 114 with schizophrenia; n = 78 with bipolar disorder; n = 87 with depression; n = 85 controls) were obtained from the Stanley Medical Research Institute. DLPFC gene expression data from a subset of 82 samples were categorized into "high" (n = 30), and "low" (n = 52) inflammation groups based on a recursive two-step cluster analysis using expression data for four inflammation-related genes. Measurements of the ratio of non-ramified to ramified microglia, a proxy of microglial activation, were available for a subset of 49 samples. All analyses controlled for age, sex, and ethnicity, as well as postmortem interval, and pH for gene expression and microglial outcomes. CMV seropositivity significantly increased the odds of a mood disorder diagnosis (bipolar disorder: OR = 2.45; major depression: OR = 3.70) and among the psychiatric samples, of suicide (OR = 2.09). Samples in the upper tercile of anti-CMV antibody titers were more likely to be members of the "high" inflammation group (OR = 4.41, an effect driven by schizophrenia and bipolar disorder samples). CMV positive samples also showed an increased ratio of non-ramified to ramified microglia in layer I of the DLPFC (Cohen's d = 0.81) as well as a non-significant increase in this ratio for the DLPFC as a whole (d = 0.56). The results raise the possibility that the reactivation of CMV contributes to the neuroinflammation that underlies some cases of psychiatric disorders.

Spatiotemporal expression patterns of ZBP1 in the brain of mouse experimental stroke model

Z-DNA binding protein 1 (ZBP1) is a cytosolic nucleic acid sensor, functioning as a critical mediator of inflammation and cell death pathways. Since neuroinflammation could occur in response to damage-associated molecular patterns (DAMPs), ZBP1 might be involved in neuroinflammation after stroke. However, the spatiotemporal expression profile of ZBP1 in the post-stroke brain remains to be elucidated. The aim of this study is to demonstrate the spatiotemporal expression patterns of ZBP1 in the post-stroke brain using a mouse photothrombotic stroke model. Real-time PCR assays showed that ZBP1 is induced on days 3-14 post stroke. ZBP1 immunoreactivity was observed in Iba1-positive microglia/macrophages in peri-infarct regions by immunohistochemistry. ZBP1-positive cells were spread in layers surrounding the infarct core by 7-14 days post stroke. Interestingly, ZBP1 immunoreactivity was also detected in CD206-positive border-associated macrophages (BAMs) in the meninges. Furthermore, ZBP1-expressing cells were positive for antibodies against inflammatory mediators such as Toll-like receptor 4 (TLR4), Toll/IL-1R domain-containing adaptor-inducing IFN-β (TRIF), and receptor-interacting serine/threonine-protein kinase 1 (RIPK1). Morphological analysis with confocal microscopy showed that the co-localization signals of ZBP1 and its adaptor, TRIF, are increased by glucose oxidase (GOx) treatment, which has been reported to induce mitochondrial DNA (mtDNA) release. These results suggest that ZBP1 is induced in peri-infarct microglia/macrophages and may be involved in DAMPs-mediated neuroinflammation involving mtDNA in the post-infarct brain.

β-Caryophyllene decreases neuroinflammation and exerts neuroprotection of dopaminergic neurons in a model of hemiparkinsonism through inhibition of the NLRP3 inflammasome

INTRODUCTION

Parkinson's disease represents a neurodegenerative condition characterized by the progressive loss of dopaminergic neurons within the Substantia Nigra pars compacta (SNpc), resulting in diminished dopamine levels in the striatum (STR) and chronic neuroinflammation. Recent investigations have proposed the neuroprotective potential of the endocannabinoid system in neurodegenerative disorders. β-caryophyllene (BCP) is recognized for its antioxidant and anti-inflammatory properties, attributed to its activation of the type 2 cannabinoid receptor. This study aimed to assess the neuroprotective impact of BCP on dopaminergic neurons, with a particular focus on inhibiting the NLRP3 inflammasome.

METHODS

A model of hemiparkinsonism, induced by 6-hydroxydopamine (6-OHDA), served as the experimental framework. Motor function was evaluated using the cylinder test, and inflammasome inhibition was determined by assessing the expression of NLRP3, caspase-1, and the pro-inflammatory cytokine IL-1β in both the SNpc and STR through ELISA analysis. Furthermore, the evaluation of oxidative stress was facilitated by quantifying malondialdehyde (MDA) levels in the same regions.

RESULTS

BCP treatment demonstrated significant improvements in motor dysfunction, as assessed by the cylinder test (p=0.0011) and exhibited a neuroprotective effect on dopaminergic neurons within the SNpc (p=0.0017), as well as nerve fibers in the STR (p=0.0399). In terms of its ability to inhibit the inflammasome, BCP led to decreased expression levels of NLRP3 (p=0.0401 in STR and p = 0.0139 in SNpc), caspase-1 (p=0.0004 in STR), and MDA (p=0.0085 in STR and p=0.0414 in SNpc).

CONCLUSION

These results point to BCP's potential in mitigating the motor deficit, inhibiting NLRP3 inflammasome activation, and attenuating lipid peroxidation induced by 6-OHDA.

CHIT1-positive microglia drive motor neuron ageing in the primate spinal cord

Ageing is a critical factor in spinal-cord-associated disorders1, yet the ageing-specific mechanisms underlying this relationship remain poorly understood. Here, to address this knowledge gap, we combined single-nucleus RNA-sequencing analysis with behavioural and neurophysiological analysis in non-human primates (NHPs). We identified motor neuron senescence and neuroinflammation with microglial hyperactivation as intertwined hallmarks of spinal cord ageing. As an underlying mechanism, we identified a neurotoxic microglial state demarcated by elevated expression of CHIT1 (a secreted mammalian chitinase) specific to the aged spinal cords in NHP and human biopsies. In the aged spinal cord, CHIT1-positive microglia preferentially localize around motor neurons, and they have the ability to trigger senescence, partly by activating SMAD signalling. We further validated the driving role of secreted CHIT1 on MN senescence using multimodal experiments both in vivo, using the NHP spinal cord as a model, and in vitro, using a sophisticated system modelling the human motor-neuron-microenvironment interplay. Moreover, we demonstrated that ascorbic acid, a geroprotective compound, counteracted the pro-senescent effect of CHIT1 and mitigated motor neuron senescence in aged monkeys. Our findings provide the single-cell resolution cellular and molecular landscape of the aged primate spinal cord and identify a new biomarker and intervention target for spinal cord degeneration.

The protective effects of EGCG was associated with HO-1 active and microglia pyroptosis inhibition in experimental intracerebral hemorrhage

Intracerebral hemorrhage (ICH), which has high mortality and disability rate is associated with microglial pyroptosis and neuroinflammation, and the effective treatment methods are limited Epigallocatechin-3-gallate (EGCG) has been found to play a cytoprotective role by regulating the anti-inflammatory response to pyroptosis in other systemic diseases. However, the role of EGCG in microglial pyroptosis and neuroinflammation after ICH remains unclear. In this study, we investigated the effects of EGCG pretreatment on neuroinflammation-mediated neuronal pyroptosis and the underlying neuroprotective mechanisms in experimental ICH. EGCG pretreatment was found to remarkably improved neurobehavioral performance, and decreased the hematoma volume and cerebral edema in mice. We found that EGCG pretreatment attenuated the release of hemin-induced inflammatory cytokines (IL-1β, IL-18, and TNF-α). EGCG significantly upregulated the expression of heme oxygenase-1 (HO-1), and downregulated the levels of pyroptotic molecules and inflammatory cytokines including Caspase-1, GSDMD, NLRP3, mature IL-1β, and IL-18. EGCG pretreatment also decreased the number of Caspase-1-positive microglia and GSDMD along with NLRP3-positive microglia after ICH. Conversely, an HO-1-specific inhibitor (ZnPP), significantly inhibited the anti-pyroptosis and anti-neuroinflammation effects of EGCG. Therefore, EGCG pretreatment alleviated microglial pyroptosis and neuroinflammation, at least in part through the Caspase-1/GSDMD/NLRP3 pathway by upregulating HO-1 expression after ICH. In addition, EGCG pretreatment promoted the polarization of microglia from the M1 phenotype to M2 phenotype after ICH. The results suggest that EGCG is a potential agent to attenuate neuroinflammation via its anti-pyroptosis effect after ICH.

Chronic alcohol induced mechanical allodynia by promoting neuroinflammation: A mouse model of alcohol-evoked neuropathic pain

BACKGROUND AND PURPOSE

Chronic pain is considered a key factor contributing to alcohol use disorder (AUD). The mechanisms responsible for chronic pain associated with chronic alcohol consumption are unknown. We evaluated the development of chronic pain in a mouse model of alcohol dependence and investigate the role of neuroinflammation.

EXPERIMENTAL APPROACH

The chronic-intermittent ethanol two-bottle choice CIE-2BC paradigm generates three groups: alcohol-dependent with escalating alcohol intake, nondependent (moderate drinking) and alcohol-naïve control male and female mice. We measured mechanical allodynia during withdrawal and after the last voluntary drinking. Immunoblotting was used to evaluate the protein levels of IBA-1, CSFR, IL-6, p38 and ERK2/1 in spinal cord tissue of dependent and non-dependent animals.

KEY RESULTS

We found significant escalation of drinking in the dependent group in male and female compared with the non-dependent group. The dependent group developed mechanical allodynia during 72 h of withdrawal, which was completely reversed after voluntary drinking. We observed an increased pain hypersensitivity compared with the naïve in 50% of non-dependent group. Increased IBA-1 and CSFR expression was observed in spinal cord tissue of both hypersensitivity-abstinence related and neuropathy-alcohol mice, and increased IL-6 expression and ERK1/2 activation in mice with hypersensitivity-related to abstinence, but not in mice with alcohol-evoked neuropathic pain.

CONCLUSIONS AND IMPLICATIONS

The CIE-2BC model induces two distinct pain conditions specific to the type of ethanol exposure: abstinence-related hypersensitivity in dependent mice and alcohol-evoked neuropathic pain in about a half of the non-dependent mice.

Purinergic neurotransmission receptor P2X4 silencing alleviates intracerebral hemorrhage-induced neuroinflammation by blocking the NLRP1/Caspase-1 pathway

This study is performed to explore the role of P2X4 in intracerebral hemorrhage (ICH) and the association between P2X4 and the NLRP1/Caspase-1 pathway. The mouse ICH model was established via collagenase injection into the right basal ganglia. P2X4 expression in brain tissues was knocked down via intracerebroventricular injection with adeno-associated virus (AAV) harboring shRNA against shP2X4. The gene expression of P2X4 and protein levels related to NLRP1 inflammasome were detected using qRT-PCR and Western blot analysis, respectively. Muramyl dipeptide (an activator of NLRP1) was used to activate NLRP1 in brain tissues. ICH induced high expression of P2X4 in mouse brain tissues. The knockdown of P2X4 alleviated short- and long-term neurological deficits of ICH mice, as well as inhibited the tissue expression and serum levels of pro-inflammatory cytokines, including TNF-α, interleukin (IL)-6, and IL-1β. Additionally, the expressions of NLRP1, ASC, and pro-Caspase-1 were down-regulated upon P2X4 silencing. Moreover, neurological impairment and the expression and secretion of cytokines after P2X4 silencing were aggravated by the additional administration of MDP. P2X4 knockdown represses neuroinflammation in brain tissues after ICH. Mechanistically, P2X4 inhibition exerts a neuroprotective effect in ICH by blocking the NLRP1/Caspase-1 pathway.

Focal mu-opioid receptor activation promotes neuroinflammation and microglial activation in the mesocorticolimbic system: Alterations induced by inflammatory pain

Microglia participates in the modulation of pain signaling. The activation of microglia is suggested to play an important role in affective disorders that are related to a dysfunction of the mesocorticolimbic system (MCLS) and are commonly associated with chronic pain. Moreover, there is evidence that mu-opioid receptors (MORs), expressed in the MCLS, are involved in neuroinflammatory events, although the way by which they do it remains to be elucidated. In this study, we propose that MOR pharmacological activation within the MCLS activates and triggers the local release of proinflammatory cytokines and this pattern of activation is impacted by the presence of systemic inflammatory pain. To test this hypothesis, we used in vivo microdialysis coupled with flow cytometry to measure cytokines release in the nucleus accumbens and immunofluorescence of IBA1 in areas of the MCLS on a rat model of inflammatory pain. Interestingly, the treatment with DAMGO, a MOR agonist locally in the nucleus accumbens, triggered the release of the IL1α, IL1β, and IL6 proinflammatory cytokines. Furthermore, MOR pharmacological activation in the ventral tegmental area (VTA) modified the levels of IBA1-positive cells in the VTA, prefrontal cortex, the nucleus accumbens and the amygdala in a dose-dependent way, without impacting mechanical nociception. Additionally, MOR blockade in the VTA prevents DAMGO-induced effects. Finally, we observed that systemic inflammatory pain altered the IBA1 immunostaining derived from MOR activation in the MSCLS. Altogether, our results indicate that the microglia-MOR relationship could be pivotal to unravel some inflammatory pain-induced comorbidities related to MCLS dysfunction.

Arterial Baroreflex Dysfunction Promotes Neuroinflammation by Activating the Platelet CD40L/Nuclear Factor Kappa B Signaling Pathway in Microglia and Astrocytes

Arterial baroreflex (ABR) dysfunction has previously been associated with neuroinflammation, the most common pathological feature of neurological disorders. However, the mechanisms mediating ABR dysfunction-induced neuroinflammation are not fully understood. In the present study, we investigated the role of platelet CD40 ligand (CD40L) in neuroinflammation in an in vivo model of ABR dysfunction, and microglia and astrocyte activation in vitro. ABR dysfunction was induced in Sprague‒Dawley rats by sinoaortic denervation (SAD). We used ELSA and immunofluorescence to assess the effect of platelet CD40L on glial cell polarization and the secretion of inflammatory factors. By flow cytometry, we found that rats subjected to SAD showed a high level of platelet microaggregation and upregulation of CD40L on the platelet surface. The promotion of platelet invasion and accumulation was also observed in the brain tissues of rats subjected to SAD. In the animal model and cultured N9 microglia/C6 astrocytoma cells, platelet CD40L overexpression promoted neuroinflammation and activated M1 microglia, A1 astrocytes, and the nuclear factor kappa B (NFκB) signaling pathway. These effects were partially blocked by inhibiting platelet activity with clopidogrel or inhibiting CD40L-mediated signaling. Our results suggest that during ABR dysfunction, CD40L signaling in platelets converts microglia to the M1 phenotype and astrocytes to the A1 phenotype, activating NFκB and resulting in neuroinflammation. Thus, our study provides a novel understanding of the pathogenesis of ABR dysfunction-induced neuroinflammation and indicates that targeting platelet CD40L is beneficial for treating central nervous system (CNS) disorders associated with ABR dysfunction.

Central role of purinergic receptors with inflammation in neuropathic pain-related macrophage-SGC-neuron triad

Adenosine triphosphate (ATP) acts on P2 purinergic receptors as an extracellular signaling molecule. P2 purinergic receptors include P2X ionotropic receptors and P2Y metabotropic receptors. Satellite glial cells (SGCs) and macrophages express P2X and P2Y receptors. Inflammatory cytokines and pro-nociceptive mediators are released by activated macrophages and SGCs, which can act on neurons to promote excitability and firing. In the primary sensory ganglia, in response to signals of injury, SGCs and macrophages accumulate around primary sensory neurons, forming a macrophage-SGC-neuron triad. In addition to affecting the pathological alterations of inflammation-related neuropathic pain, inflammatory cytokines and pro-nociceptive mediators are released by the action of ATP on P2X and P2Y receptors in macrophages and SGCs. Macrophages and SGCs work together to enhance and prolong neuropathic pain. The macrophage-SGC-neuron triad communicates with each other through ATP and other inflammatory mediators and maintains and promotes the initiation and development of inflammation related-neuropathic pain. This article is part of the Special Issue on "Purinergic Signaling: 50 years".

Modulation of virus-induced neuroinflammation by the autophagy receptor SHISA9 in mice

Microglia and astrocytes are subgroups of brain glia cells that support and protect neurons within the central nervous system (CNS). At early stages of viral infection in the CNS, they are predominant responding cells and lead to recruitment of peripheral immune cells for viral clearance. Inhibitor of nuclear factor κB kinase subunit epsilon (IKKi) is critical for type I interferon signalling and inflammation, which modulate heterogenic immune responses during CNS infection. Balanced autophagy is vital to maintain brain integrity, yet regulation of autophagy and immune activity within brain glia cells is poorly understood. Here we identify SHISA9 as an autophagy cargo receptor that mediates the autophagy-dependent degradation of IKKi during herpes simplex virus type 1 infection. IKKi is recognized by SHISA9 through unanchored K48-linked poly-ubiquitin chains and bridged to autophagosome membrane components GABARAPL1. Single-cell RNA sequencing analysis shows that SHISA9 has temporal characteristics while modulating both antiviral and inflammatory responses in microglia and astrocytes at different stages during viral infection. We found that Shisa9-/- mice are highly susceptible to herpes simplex virus encephalitis, have pathogenic astrocytes and display more severe neuroinflammation compared with wild-type mice. Taken together, our study unravels a critical role of selective autophagy by orchestrating immune heterogeneity of different CNS resident cells through the SHISA9-IKKi axis.

ApoE isoform- and microbiota-dependent progression of neurodegeneration in a mouse model of tauopathy

Tau-mediated neurodegeneration is a hallmark of Alzheimer's disease. Primary tauopathies are characterized by pathological tau accumulation and neuronal and synaptic loss. Apolipoprotein E (ApoE)-mediated neuroinflammation is involved in the progression of tau-mediated neurodegeneration, and emerging evidence suggests that the gut microbiota regulates neuroinflammation in an APOE genotype-dependent manner. However, evidence of a causal link between the microbiota and tau-mediated neurodegeneration is lacking. In this study, we characterized a genetically engineered mouse model of tauopathy expressing human ApoE isoforms reared under germ-free conditions or after perturbation of their gut microbiota with antibiotics. Both of these manipulations reduced gliosis, tau pathology, and neurodegeneration in a sex- and ApoE isoform-dependent manner. The findings reveal mechanistic and translationally relevant interrelationships between the microbiota, neuroinflammation, and tau-mediated neurodegeneration.

Oxidative Stress-Induced HMGB1 Translocation in Myenteric Neurons Contributes to Neuropathy in Colitis

High-mobility group box 1 (HMGB1) is a damage-associated molecular pattern released by dying cells to stimulate the immune response. During cell death, HMGB1 is translocated from the nucleus to the cytoplasm and passively released. High levels of secreted HMGB1 are observed in the faeces of inflammatory bowel disease (IBD) patients, indicating its role in IBD pathophysiology and potential as a non-invasive IBD biomarker. HMGB1 is important in regulating neuronal damage in the central nervous system; its pathological activity is intertwined with oxidative stress and inflammation. In this study, HMGB1 expression in the enteric nervous system and its relevance to intestinal neuroinflammation is explored in organotypic cultures of the myenteric plexus exposed to oxidative stimuli and in Winnie mice with spontaneous chronic colitis. Oxidative stimuli induced cytoplasmic translocation of HMGB1 in myenteric neurons in organotypic preparations. HMGB1 translocation correlated with enteric neuronal loss and oxidative stress in the myenteric ganglia of Winnie mice. Inhibition of HMGB1 by glycyrrhizic acid ameliorated HMGB1 translocation and myenteric neuronal loss in Winnie mice. These data highlight modulation of HMGB1 signalling as a therapeutic strategy to reduce the consequences of enteric neuroinflammation in colitis, warranting the exploration of therapeutics acting on the HMGB1 pathway as an adjunct treatment with current anti-inflammatory agents.

Neuroinflammation and COVID-19 Ischemic Stroke Recovery—Evolving Evidence for the Mediating Roles of the ACE2/Angiotensin-(1–7)/Mas Receptor Axis and NLRP3 Inflammasome

Cerebrovascular events, notably acute ischemic strokes (AIS), have been reported in the setting of novel coronavirus disease (COVID-19) infection. Commonly regarded as cryptogenic, to date, the etiology is thought to be multifactorial and remains obscure; it is linked either to a direct viral invasion or to an indirect virus-induced prothrombotic state, with or without the presence of conventional cerebrovascular risk factors. In addition, patients are at a greater risk of developing long-term negative sequelae, i.e., long-COVID-related neurological problems, when compared to non-COVID-19 stroke patients. Central to the underlying neurobiology of stroke recovery in the context of COVID-19 infection is reduced angiotensin-converting enzyme 2 (ACE2) expression, which is known to lead to thrombo-inflammation and ACE2/angiotensin-(1–7)/mitochondrial assembly receptor (MasR) (ACE2/Ang-(1-7)/MasR) axis inhibition. Moreover, after AIS, the activated nucleotide-binding oligomerization domain (NOD)-like receptor (NLR) family pyrin domain-containing 3 (NLRP3) inflammasome may heighten the production of numerous proinflammatory cytokines, mediating neuro-glial cell dysfunction, ultimately leading to nerve-cell death. Therefore, potential neuroprotective therapies targeting the molecular mechanisms of the aforementioned mediators may help to inform rehabilitation strategies to improve brain reorganization (i.e., neuro-gliogenesis and synaptogenesis) and secondary prevention among AIS patients with or without COVID-19. Therefore, this narrative review aims to evaluate the mediating role of the ACE2/Ang- (1-7)/MasR axis and NLRP3 inflammasome in COVID-19-mediated AIS, as well as the prospects of these neuroinflammation mediators for brain repair and in secondary prevention strategies against AIS in stroke rehabilitation.

A novel targeted approach to delineate a role for estrogen receptor-β in ameliorating murine mammary tumor-associated neuroinflammation

PURPOSE

Circulating estrogens in breast cancer patients and survivors are often extremely low due to menopause and estrogen-reducing cancer treatments. Simultaneously, circulating inflammatory markers, and inflammatory proteins in brains of rodent tumor models, can be elevated and correlate with debilitating neurological and psychological comorbidities. Because estrogen has anti-inflammatory properties in the brain, we hypothesized that mammary tumor-induced neuroinflammation is driven, in part, by reduced brain estrogen signaling.

METHODS

An ovariectomized mouse model of postmenopausal breast cancer utilizing the ERα-positive 67NR mammary tumor cell line was used for these experiments. A novel, orally bioavailable, and brain penetrant ERβ agonist was administered daily via oral gavage. Following treatment, estrogen-responsive genes were measured in brain regions. Central and circulating inflammatory markers were measured via RT-qPCR and a multiplex cytokine array, respectively.

RESULTS

We present novel findings that peripheral mammary tumors alter estrogen signaling genes including receptors and aromatase in the hypothalamus, hippocampus, and frontal cortex. Mammary tumors induced peripheral and central inflammation, however, pharmacological ERβ activation was not sufficient to reduce this inflammation.

CONCLUSIONS

Data presented here suggest that compensating for low circulating estrogen with ERβ brain activation is not sufficient to attenuate mammary tumor-induced neuroinflammation, and is therefore not a likely candidate for the treatment of behavioral symptoms in patients. The novel finding that mammary tumors alter estrogen signaling-related genes is a clinically relevant advancement to the understanding of how peripheral tumor biology modulates neurobiology. This is necessary to predict and prevent behavioral comorbidities (e.g., cognitive impairment) prevalent in cancer patients and survivors.

Pharmacological Inhibition of Spermine Oxidase Suppresses Excitotoxicity Induced Neuroinflammation in Mouse Retina

Polyamine oxidation plays a major role in neurodegenerative diseases. Previous studies from our laboratory demonstrated that spermine oxidase (SMOX, a member of the polyamine oxidase family) inhibition using MDL 72527 reduced neurodegeneration in models of retinal excitotoxicity and diabetic retinopathy. However, the mechanisms behind the neuroprotection offered by SMOX inhibition are not completely studied. Utilizing the experimental model of retinal excitotoxicity, the present study determined the impact of SMOX blockade in retinal neuroinflammation. Our results demonstrated upregulation in the number of cells positive for Iba-1 (ionized calcium-binding adaptor molecule 1), CD (Cluster Differentiation) 68, and CD16/32 in excitotoxicity-induced retinas, while MDL 72527 treatment reduced these changes, along with increases in the number of cells positive for Arginase1 and CD206. When retinal excitotoxicity upregulated several pro-inflammatory genes, MDL 72527 treatment reduced many of them and increased anti-inflammatory genes. Furthermore, SMOX inhibition upregulated antioxidant signaling (indicated by elevated Nrf2 and HO-1 levels) and reduced protein-conjugated acrolein in excitotoxic retinas. In vitro studies using C8-B4 cells showed changes in cellular morphology and increased reactive oxygen species formation in response to acrolein (a product of SMOX activity) treatment. Overall, our findings indicate that the inhibition SMOX pathway reduced neuroinflammation and upregulated antioxidant signaling in the retina.

The histone deacetylase inhibitor belinostat ameliorates experimental autoimmune encephalomyelitis in mice by inhibiting TLR2/MyD88 and HDAC3/ NF-κB p65-mediated neuroinflammation

Multiple sclerosis (MS) is a Th cell-mediated inflammatory demyelinating autoimmune disease. MS cannot be cured, and long-term drug treatment is still needed for MS patients. In this study, we examined the effect of belinostat, a pan-histone deacetylase inhibitor (HDACi), on experimental autoimmune encephalomyelitis (EAE) and elucidated its mechanism of action. We found that belinostat alleviates the clinical symptoms, histopathological central nervous system (CNS) inflammation and demyelination outcomes in EAE mice. Compared to the MS oral drug dimethyl fumarate (DMF) (100 mg/kg), belinostat (30 mg/kg) treatment exhibited better efficacy in improving the clinical symptoms of EAE mice. Belinostat treatment significantly suppressed the activation of M1 microglia and the proinflammatory cytokine expression; but it had no effects on the M2 microglial polarization. Belinostat also decreased both NO and iNOS levels in LPS-stimulated BV2 microglia. Accordingly, belinostat treatment of EAE mice significantly inhibited activation of the TLR2/MyD88 signaling pathway and downregulated the expression of HDAC3 while upregulating the acetylated NF-κB p65 levels. Taken together, these data demonstrate for the first time that belinostat ameliorates EAE in mice through inhibiting neuroinflammation via suppressing M1 microglial polarization, and implicating belinostat as a potential candidate for the treatment of multiple sclerosis.

Fat and Protein Combat Triggers Immunological Weapons of Innate and Adaptive Immune Systems to Launch Neuroinflammation in Parkinson's Disease

Parkinson's disease (PD) is the second-most common neurodegenerative disease in the world, affecting up to 10 million people. This disease mainly happens due to the loss of dopaminergic neurons accountable for memory and motor function. Partial glucocerebrosidase enzyme deficiency and the resultant excess accumulation of glycosphingolipids and alpha-synuclein (α-syn) aggregation have been linked to predominant risk factors that lead to neurodegeneration and memory and motor defects in PD, with known and unknown causes. An increasing body of evidence uncovers the role of several other lipids and their association with α-syn aggregation, which activates the innate and adaptive immune system and sparks brain inflammation in PD. Here, we review the emerging role of a number of lipids, i.e., triglyceride (TG), diglycerides (DG), glycerophosphoethanolamines (GPE), polyunsaturated fatty acids (PUFA), sphingolipids, gangliosides, glycerophospholipids (GPL), and cholesterols, and their connection with α-syn aggregation as well as the induction of innate and adaptive immune reactions that trigger neuroinflammation in PD.

Neuroinflammatory Profiling in SIV-Infected Chinese-Origin Rhesus Macaques on Antiretroviral Therapy

The central nervous system (CNS) HIV reservoir is an obstacle to achieving an HIV cure. The basal ganglia harbor a higher frequency of SIV than other brain regions in the SIV-infected rhesus macaques of Chinese-origin (chRMs) even on suppressive combination antiretroviral therapy (ART). Since residual HIV/SIV reservoir is associated with inflammation, we characterized the neuroinflammation by gene expression and systemic levels of inflammatory molecules in healthy controls and SIV-infected chRMs with or without ART. CCL2, IL-6, and IFN-γ were significantly reduced in the cerebrospinal fluid (CSF) of animals receiving ART. Moreover, there was a correlation between levels of CCL2 in plasma and CSF, suggesting the potential use of plasma CCL2 as a neuroinflammation biomarker. With higher SIV frequency, the basal ganglia of untreated SIV-infected chRMs showed an upregulation of secreted phosphoprotein 1 (SPP1), which could be an indicator of ongoing neuroinflammation. While ART greatly reduced neuroinflammation in general, proinflammatory genes, such as IL-9, were still significantly upregulated. These results expand our understanding of neuroinflammation and signaling in SIV-infected chRMs on ART, an excellent model to study HIV/SIV persistence in the CNS.

Is There a Link between Oropharyngeal Microbiome and Schizophrenia? A Narrative Review

The study aimed to examine the impact of the oropharyngeal microbiome in the pathophysiology of schizophrenia and to clarify whether there might be a bidirectional link between the oral microbiota and the brain in a context of dysbiosis-related neuroinflammation. We selected nine articles including three systemic reviews with several articles from the same research team. Different themes emerged, which we grouped into 5 distinct parts concerning the oropharyngeal phageome, the oropharyngeal microbiome, the salivary microbiome and periodontal disease potentially associated with schizophrenia, and the impact of drugs on the microbiome and schizophrenia. We pointed out the presence of phageoma in patients suffering from schizophrenia and that periodontal disease reinforces the role of inflammation in the pathophysiology of schizophrenia. Moreover, saliva could be an interesting substrate to characterize the different stages of schizophrenia. However, the few studies we have on the subject are limited in scope, and some of them are the work of a single team. At this stage of knowledge, it is difficult to conclude on the existence of a bidirectional link between the brain and the oral microbiome. Future studies on the subject will clarify these questions that for the moment remain unresolved.

Erinacine A Prevents Lipopolysaccharide-Mediated Glial Cell Activation to Protect Dopaminergic Neurons against Inflammatory Factor-Induced Cell Death In Vitro and In Vivo

Hericium erinaceus (HE) is a common edible mushroom consumed in several Asian countries and considered to be a medicinal mushroom with neuroprotective effects. Erinacine A (EA) is a bioactive compound in Hericium erinaceus mycelium (HEM) that has been shown to have a neuroprotective effect against neurodegenerative diseases, e.g., Parkinson’s disease (PD). Although the etiology of PD is still unclear, neuroinflammation may play an important role in causing dopaminergic neuron loss, which is a pathological hallmark of PD. However, glial cell activation has a close relationship with neuroinflammation. Thus, this study aimed to investigate the anti-neuroinflammatory and neuroprotective effects of EA on lipopolysaccharide (LPS)-induced glial cell activation and neural damage in vitro and in vivo. For the in vitro experiments, glial cells, BV-2 microglial cells and CTX TNA2 astrocytes were pretreated with EA and then stimulated with LPS and/or IFN-γ. The expression of proinflammatory factors in the cells and culture medium was analyzed. In addition, differentiated neuro-2a (N2a) cells were pretreated with EA or HEM and then stimulated with LPS-treated BV-2 conditioned medium (CM). The cell viability and the amount of tyrosine hydroxylase (TH) and mitogen-activated protein kinases (MAPKs) were analyzed. In vivo, rats were given EA or HEM by oral gavage prior to injection of LPS into the substantia nigra (SN). Motor coordination of the rats and the expression of proinflammatory mediators in the midbrain were analyzed. EA pretreatment prevented LPS-induced iNOS expression and NO production in BV-2 cells and TNF-α expression in CTX TNA2 cells. In addition, both EA and HEM pretreatment significantly increased cell viability and TH expression and suppressed the phosphorylation of JNK and NF- κB in differentiated N2a cells treated with CM. In vivo, both EA and HEM significantly improved motor dysfunction in the rotarod test and the amphetamine-induced rotation test and reduced the expression of TNF-α, IL-1β and iNOS in the midbrain of rats intranigrally injected with LPS. The results demonstrate that EA ameliorates LPS-induced neuroinflammation and has neuroprotective properties.