The Ang-(1-7)/MasR axis ameliorates neuroinflammation in hypothermic traumatic brain injury in mice by modulating phenotypic transformation of microglia.

The Ang-(1-7)/MasR axis is critically involved in treating several diseases; For example, Ang-(1-7) improves inflammatory response and neurological function after traumatic brain injury and inhibits post-inflammatory hypothermia. However, its function in traumatic brain injury (TBI) combined with seawater immersion hypothermia remains unclear. Here, we used a mice model of hypothermic TBI and a BV2 cell model of hypothermic inflammation to investigate whether the Ang-(1-7)/MasR axis is involved in ameliorating hypothermic TBI. Quantitative reverse transcription PCR, western blotting assay, and immunofluorescence assay were performed to confirm microglia polarization and cytokine regulation. Hematoxylin-eosin staining, Nissl staining, and immunohistochemical assay were conducted to assess the extent of hypothermic TBI-induced damage and the ameliorative effect of Ang-(1-7) in mice. An open field experiment and neurological function scoring with two approaches were used to assess the degree of recovery and prognosis in mice. After hypothermic TBI establishment in BV2 cells, the Ang-(1-7)/MasR axis induced phenotypic transformation of microglia from M1 to M2, inhibited IL-6 and IL-1ß release, and upregulated IL-4 and IL-10 levels. After hypothermic TBI development in mice, intraperitoneally administered Ang-(1-7) attenuated histological damage and promoted neurological recovery. These findings suggest that hypothermia exacerbates TBI-induced damage and that the Ang-(1-7)/MasR axis can ameliorate hypothermic TBI and directly affect prognosis.

FGF21 attenuates neuroinflammation following subarachnoid hemorrhage through promoting mitophagy and inhibiting the cGAS-STING pathway.

BACKGROUND: Subarachnoid hemorrhage (SAH) represents a form of cerebrovascular event characterized by a notable mortality and morbidity rate. Fibroblast growth factor 21 (FGF21), a versatile hormone predominantly synthesized by the hepatic tissue, has emerged as a promising neuroprotective agent. Nevertheless, the precise impacts and underlying mechanisms of FGF21 in the context of SAH remain enigmatic. METHODS: To elucidate the role of FGF21 in inhibiting the microglial cGAS-STING pathway and providing protection against SAH-induced cerebral injury, a series of cellular and molecular techniques, including western blot analysis, real-time polymerase chain reaction, immunohistochemistry, RNA sequencing, and behavioral assays, were employed. RESULTS: Administration of recombinant fibroblast growth factor 21 (rFGF21) effectively mitigated neural apoptosis, improved cerebral edema, and attenuated neurological impairments post-SAH. Transcriptomic analysis revealed that SAH triggered the upregulation of numerous genes linked to innate immunity, particularly those involved in the type I interferon (IFN-I) pathway and microglial function, which were notably suppressed upon adjunctive rFGF21 treatment. Mechanistically, rFGF21 intervention facilitated mitophagy in an AMP-activated protein kinase (AMPK)-dependent manner, thereby preventing mitochondrial DNA (mtDNA) release into the cytoplasm and dampening the activation of the DNA-sensing cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) signaling pathway. Conditional knockout of STING in microglia markedly ameliorated the inflammatory response and mitigated secondary brain injuries post-SAH. CONCLUSION: Our results present the initial evidence that FGF21 confers a protective effect against neuroinflammation-associated brain damage subsequent to SAH. Mechanistically, we have elucidated a novel pathway by which FGF21 exerts this neuroprotection through inhibition of the cGAS-STING signaling cascade.

Dysregulated brain-gut axis in the setting of traumatic brain injury: review of mechanisms and anti-inflammatory pharmacotherapies.

Traumatic brain injury (TBI) is a chronic and debilitating disease, associated with a high risk of psychiatric and neurodegenerative diseases. Despite significant advancements in improving outcomes, the lack of effective treatments underscore the urgent need for innovative therapeutic strategies. The brain-gut axis has emerged as a crucial bidirectional pathway connecting the brain and the gastrointestinal (GI) system through an intricate network of neuronal, hormonal, and immunological pathways. Four main pathways are primarily implicated in this crosstalk, including the systemic immune system, autonomic and enteric nervous systems, neuroendocrine system, and microbiome. TBI induces profound changes in the gut, initiating an unrestrained vicious cycle that exacerbates brain injury through the brain-gut axis. Alterations in the gut include mucosal damage associated with the malabsorption of nutrients/electrolytes, disintegration of the intestinal barrier, increased infiltration of systemic immune cells, dysmotility, dysbiosis, enteroendocrine cell (EEC) dysfunction and disruption in the enteric nervous system (ENS) and autonomic nervous system (ANS). Collectively, these changes further contribute to brain neuroinflammation and neurodegeneration via the gut-brain axis. In this review article, we elucidate the roles of various anti-inflammatory pharmacotherapies capable of attenuating the dysregulated inflammatory response along the brain-gut axis in TBI. These agents include hormones such as serotonin, ghrelin, and progesterone, ANS regulators such as beta-blockers, lipid-lowering drugs like statins, and intestinal flora modulators such as probiotics and antibiotics. They attenuate neuroinflammation by targeting distinct inflammatory pathways in both the brain and the gut post-TBI. These therapeutic agents exhibit promising potential in mitigating inflammation along the brain-gut axis and enhancing neurocognitive outcomes for TBI patients.

Polyphyllin I alleviates neuroinflammation after cerebral ischemia-reperfusion injury via facilitating autophagy-mediated M2 microglial polarization.

Microglial activation and polarization play a central role in poststroke inflammation and neuronal damage. Modulating microglial polarization from pro-inflammatory to anti-inflammatory phenotype is a promising therapeutic strategy for the treatment of cerebral ischemia. Polyphyllin I (PPI), a steroidal saponin, shows multiple bioactivities in various diseases, but the potential function of PPI in cerebral ischemia is not elucidated yet. In our study, the influence of PPI on cerebral ischemia-reperfusion injury was evaluated. Mouse middle cerebral artery occlusion (MCAO) model and oxygen-glucose deprivation and reoxygenation (OGD/R) model were constructed to mimic cerebral ischemia-reperfusion injury in vivo and in vitro. TTC staining, TUNEL staining, RT-qPCR, ELISA, flow cytometry, western blot, immunofluorescence, hanging wire test, rotarod test and foot-fault test, open-field test and Morris water maze test were performed in our study. We found that PPI alleviated cerebral ischemia-reperfusion injury and neuroinflammation, and improved functional recovery of mice after MCAO. PPI modulated microglial polarization towards anti-inflammatory M2 phenotype in MCAO mice in vivo and post OGD/R in vitro. Besides, PPI promoted autophagy via suppressing Akt/mTOR signaling in microglia, while inhibition of autophagy abrogated the effect of PPI on M2 microglial polarization after OGD/R. Furthermore, PPI facilitated autophagy-mediated ROS clearance to inhibit NLRP3 inflammasome activation in microglia, and NLRP3 inflammasome reactivation by nigericin abolished the effect of PPI on M2 microglia polarization. In conclusion, PPI alleviated post-stroke neuroinflammation and tissue damage via increasing autophagy-mediated M2 microglial polarization. Our data suggested that PPI had potential for ischemic stroke treatment.

Oroxin A alleviates early brain injury after subarachnoid hemorrhage by regulating ferroptosis and neuroinflammation.

BACKGROUND: Subarachnoid hemorrhage (SAH), a severe subtype of stroke, is characterized by notably high mortality and morbidity, largely due to the lack of effective therapeutic options. Although the neuroprotective potential of PPARg and Nrf2 has been recognized, investigative efforts into oroxin A (OA), remain limited in preclinical studies. METHODS: SAH was modeled in vivo through filament perforation in male C57BL/6 mice and in vitro by exposing HT22 cells to hemin to induce neuronal damage. Following the administration of OA, a series of methods were employed to assess neurological behaviors, brain water content, neuronal damage, cell ferroptosis, and the extent of neuroinflammation. RESULTS: The findings indicated that OA treatment markedly improved survival rates, enhanced neurological functions, mitigated neuronal death and brain edema, and attenuated the inflammatory response. These effects of OA were linked to the suppression of microglial activation. Moreover, OA administration was found to diminish ferroptosis in neuronal cells, a critical factor in early brain injury (EBI) following SAH. Further mechanistic investigations uncovered that OA facilitated the translocation of nuclear factor erythroid 2-related factor 2 (Nrf-2) from the cytoplasm to the nucleus, thereby activating the Nrf2/GPX4 pathway. Importantly, OA also upregulated the expression of FSP1, suggesting a significant and parallel protective effect against ferroptosis in EBI following SAH in synergy with GPX4. CONCLUSION: In summary, this research indicated that the PPARg activator OA augmented the neurological results in rodent models and diminished neuronal death. This neuroprotection was achieved primarily by suppressing neuronal ferroptosis. The underlying mechanism was associated with the alleviation of cellular death through the Nrf2/GPX4 and FSP1/CoQ10 pathways.

Seipin Deficiency Leads to Energy Dyshomeostasis via Inducing Hypothalamic Neuroinflammation and Aberrant Expression of Neuropeptides.

Seipin is a key regulator of lipid metabolism, the deficiency of which leads to severe lipodystrophy. Hypothalamus is the pivotal center of brain that modulates appetite and energy homeostasis, where Seipin is abundantly expressed. Whether and how Seipin deficiency leads to systemic metabolic disorders via hypothalamus-involved energy metabolism dysregulation remains to be elucidated. In the present study, we demonstrated that Seipin-deficiency induced hypothalamic inflammation, reduction of anorexigenic pro-opiomelanocortin (POMC), and elevation of orexigenic agonist-related peptide (AgRP). Importantly, administration of rosiglitazone, a thiazolidinedione antidiabetic agent, rescued POMC and AgRP expression, suppressed hypothalamic inflammation, and restored energy homeostasis in Seipin knockout mice. Our findings offer crucial insights into the mechanism of Seipin deficiency-associated energy imbalance and indicates that rosiglitazone could serve as potential intervening agent towards metabolic disorders linked to Seipin.

Function and Mechanism of Abscisic Acid on Microglia-Induced Neuroinflammation in Parkinson's Disease.

Parkinson's disease (PD), as a neurologically implemented disease with complex etiological factors, has a complex and variable pathogenesis. Accompanying further research, neuroinflammation has been found to be one of the possible factors in its pathogenesis. Microglia, as intrinsic immune cells in the brain, play an important role in maintaining microenvironmental homeostasis in the brain. However, over-activation of neurotoxic microglia in PD promotes neuroinflammation, which further increases dopaminergic (DA) neuronal damage and exacerbates the disease process. Therefore, targeting and regulating the functional state of microglia is expected to be a potential avenue for PD treatment. In addition, plant extracts have shown great potential in the treatment of neurodegenerative disorders due to their abundant resources, mild effects, and the presence of multiple active ingredients. However, it is worth noting that some natural products have certain toxic side effects, so it is necessary to pay attention to distinguish medicinal ingredients and usage and dosage when using to avoid aggravating the progression of diseases. In this review, the roles of microglia with different functional states in PD and the related pathways inducing microglia to transform into neuroprotective states are described. At the same time, it is discussed that abscisic acid (ABA) may regulate the polarization of microglia by targeting them, promote their transformation into neuroprotective state, reduce the neuroinflammatory response in PD, and provide a new idea for the treatment of PD and the selection of drugs.

Experimental Models to Study Immune Dysfunction in the Pathogenesis of Parkinson's Disease.

Parkinson's disease (PD) is a chronic, age-related, progressive multisystem disease associated with neuroinflammation and immune dysfunction. This review discusses the methodological approaches used to study the changes in central and peripheral immunity in PD, the advantages and limitations of the techniques, and their applicability to humans. Although a single animal model cannot replicate all pathological features of the human disease, neuroinflammation is present in most animal models of PD and plays a critical role in understanding the involvement of the immune system (IS) in the pathogenesis of PD. The IS and its interactions with different cell types in the central nervous system (CNS) play an important role in the pathogenesis of PD. Even though culture models do not fully reflect the complexity of disease progression, they are limited in their ability to mimic long-term effects and need validation through in vivo studies. They are an indispensable tool for understanding the interplay between the IS and the pathogenesis of this disease. Understanding the immune-mediated mechanisms may lead to potential therapeutic targets for the treatment of PD. We believe that the development of methodological guidelines for experiments with animal models and PD patients is crucial to ensure the validity and consistency of the results.

[Research progress on the role of microglia in sepsis-associated encephalopathy].

Sepsis-associated encephalopathy (SAE) refers to diffuse brain dysfunction caused by sepsis, which is characterized by decreased attention, directional impairment, being prone to irritation, and in severe cases the patient will experience drowsiness and coma. The pathogenesis of SAE mainly includes neuroinflammation, damage of blood-brain barrier, cerebral vascular dysfunction, and neurometabolic changes, among which neuroinflammation is the core pathological process. Microglia are considered to be important immune cells of the central nervous system and play an important role in neuroinflammation. This article systematically describes the role of microglia in the development of SAE, and discusses the phenotype and related signaling pathways of microglia, in order to clarify the role of microglia in SAE and provide a theoretical basis for clinical treatment of SAE.

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-1ß, 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.

Long-Term Accumulation of T Cytotoxic 1, T Cytotoxic 17, and T Cytotoxic 17/1 Cells in the Brain Contributes to Microglia-Mediated Chronic Neuroinflammation After Ischemic Stroke.

Post-stroke neuroinflammation affects the damage and recovery of neurological functions. T cells including CD8+ T cells were present in the ipsilateral hemisphere in the subacute and late phases of ischemic stroke. However, the potential roles of CD8+ T cell subsets in the progression of neuroinflammation have not been characterized. In the current mouse transient middle cerebral artery occlusion model, we investigated the existence of CD8+ T cell subsets in the ipsilateral hemisphere in the subacute and late phases of stroke. We found that ipsilateral CD8+ T cells were present on post-stroke day 3 and increased on post-stroke day 30. The day-3 ipsilateral CD8+ T cells predominantly produced interferon-γ (IFN-γ), while the day-30 ipsilateral CD8+ T cells co-expressed IFN-γ and interleukin-17A (IL-17A). In addition, evaluation of cytokines and transcription factors of the day-30 ipsilateral CD8+ T cells revealed the presence of T cytotoxic 1 (Tc1), T cytotoxic 17 (Tc17), and T cytotoxic 17/1 (Tc17/1) cells. Furthermore, based on the expression of a series of chemokine/cytokine receptors, viable ipsilateral Tc1, Tc17, and Tc17.1 cells were identified and enriched from the day-30 ipsilateral CD8+ T cells, respectively. Co-culture of microglia with ipsilateral Tc1, Tc17, or Tc17.1 cells indicated that the three CD8+ T cell subsets up-regulated the expression of pro-inflammatory mediators by microglia, with Tc17.1 cells being the most potent cell in doing so. Collectively, this study sheds light on the contributions of Tc1, Tc17, and Tc17.1 cells to long-term neuroinflammation after ischemic stroke.

The emerging importance of skull-brain interactions in traumatic brain injury.

The recent identification of skull bone marrow as a reactive hematopoietic niche that can contribute to and direct leukocyte trafficking into the meninges and brain has transformed our view of this bone structure from a solid, protective casing to a living, dynamic tissue poised to modulate brain homeostasis and neuroinflammation. This emerging concept may be highly relevant to injuries that directly impact the skull such as in traumatic brain injury (TBI). From mild concussion to severe contusion with skull fracturing, the bone marrow response of this local myeloid cell reservoir has the potential to impact not just the acute inflammatory response in the brain, but also the remodeling of the calvarium itself, influencing its response to future head impacts. If we borrow understanding from recent discoveries in other CNS immunological niches and extend them to this nascent, but growing, subfield of neuroimmunology, it is not unreasonable to consider the hematopoietic compartment in the skull may similarly play an important role in health, aging, and neurodegenerative disease following TBI. This literature review briefly summarizes the traditional role of the skull in TBI and offers some additional insights into skull-brain interactions and their potential role in affecting secondary neuroinflammation and injury outcomes.

Adjudin protects blood-brain barrier integrity and attenuates neuroinflammation following intracerebral hemorrhage in mice.

Secondary brain injury exacerbates neurological dysfunction and neural cell death following intracerebral hemorrhage (ICH), targeting the pathophysiological mechanism of the secondary brain injury holds promise for improving ICH outcomes. Adjudin, a potential male contraceptive, exhibits neuroprotective effects in brain injury disease models, yet its impact in the ICH model remains unknown. In this study, we investigated the effects of adjudin on brain injury in a mouse ICH model and explored its underlying mechanisms. ICH was induced in male C57BL/6 mice by injecting collagenase into the right striatum. Mice received adjudin treatment (50 mg/kg/day) for 3 days before euthanization and the perihematomal tissues were collected for further analysis. Adjudin significantly reduced hematoma volume and improved neurological function compared with the vehicle group. Western blot showed that Adjudin markedly decreased the expression of MMP-9 and increased the expression of tight junctions (TJs) proteins, Occludin and ZO-1, and adherens junctions (AJs) protein VE-cadherin. Adjudin also decreased the blood-brain barrier (BBB) permeability, as indicated by the reduced albumin and Evans Blue leakage, along with a decrease in brain water content. Immunofluorescence staining revealed that adjudin noticeably reduced the infiltration of neutrophil, activation of microglia/macrophages, and reactive astrogliosis, accompanied by an increase in CD206 positive microglia/macrophages which exhibit phagocytic characteristics. Adjudin concurrently decreased the generation of proinflammatory cytokines, such as TNF-α and IL-1ß. Additionally, adjudin increased the expression of aquaporin 4 (AQP4). Furthermore, adjudin reduced brain cell apoptosis, as evidenced by increased expression of anti-apoptotic protein Bcl-2, and decreased expression of apoptosis related proteins Bax, cleaved caspase-3 and fewer TUNEL positive cells. Our data suggest that adjudin protects against ICH-induced secondary brain injury and may serve as a potential neuroprotective agent for ICH treatment.

APOE2 gene therapy reduces amyloid deposition and improves markers of neuroinflammation and neurodegeneration in a mouse model of Alzheimer disease.

Epidemiological studies show that individuals who carry the relatively uncommon APOE ε2 allele rarely develop Alzheimer disease, and if they do, they have a later age of onset, milder clinical course, and less severe neuropathological findings than people without this allele. The contrast is especially stark when compared with the major genetic risk factor for Alzheimer disease, APOE ε4, which has an age of onset several decades earlier, a more aggressive clinical course and more severe neuropathological findings, especially in terms of the amount of amyloid deposition. Here, we demonstrate that brain exposure to APOE ε2 via a gene therapy approach, which bathes the entire cortical mantle in the gene product after transduction of the ependyma, reduces Aß plaque deposition, neurodegenerative synaptic loss, and, remarkably, reduces microglial activation in an APP/PS1 mouse model despite continued expression of human APOE ε4. This result suggests a promising protective effect of exogenous APOE ε2 and reveals a cell nonautonomous effect of the protein on microglial activation, which we show is similar to plaque-associated microglia in the brain of Alzheimer disease patients who inherit APOE ε2. These data increase the potential that an APOE ε2 therapeutic could be effective in Alzheimer disease, even in individuals born with the risky ε4 allele.

Nrf2 activation by neferine mitigates microglial neuroinflammation after subarachnoid hemorrhage through inhibiting TAK1-NF-κB signaling.

Oxidative stress and neuroinflammation are two major causes leading to early brain injury after subarachnoid hemorrhage (SAH). Nuclear factor E2-related factor 2 (Nrf2) is a critical transcription factor that contributes to antioxidant responses. Additionally, Nrf2 could inhibit transforming growth factor beta-activated kinase 1 (TAK1), which plays a vital role in microglial activation-mediated neuroinflammation. Neferine (NE) exhibits considerable protective effects in diverse disease models. However, the detailed effect and mechanism of NE on SAH remain unknown. Our data showed that NE treatment significantly reduced behavior and cognitive impairment, and brain edema in the early period after SAH. In addition, NE mitigated SAH-induced oxidative damage, neuroinflammation, and neural death. Moreover, NE inhibited M1 microglial polarization and enhanced M2 phenotype microglia both in vivo and in vitro. Further investigations revealed that NE enhanced the Nrf2-antioxidant response element (ARE) signaling pathway and suppressed TAK1-NF-κB signaling. In contrast, depletion of Nrf2 by ML385 suppressed Nrf2-ARE signaling, induced TAK1-NF-κB activation, and further promoted M1 microglial polarization. Additionally, ML385 abated the neuroprotective effects of NE against SAH. Notably, LPS also aggravated TAK1-NF-κB activation and reversed the beneficial effects of NE after SAH. In summary, NE provides protection after SAH by inhibiting oxidative stress and modulating microglial polarization through Nrf2 activation and TAK1-NF-κB suppression.

Mood disturbances in newly diagnosed Parkinson's Disease patients reflect intrathecal inflammation.

In Parkinson's disease (PD), neuroinflammation may be involved in the pathogenesis of mood disorders, contributing to the clinical heterogeneity of the disease. The cerebrospinal fluid (CSF) levels of interleukin (IL)-1ß, IL-2, IL-6, IL-7, IL-8, IL-9, IL-12, IL-17, interferon (IFN)γ, macrophage inflammatory protein 1-alpha (MIP-1a), MIP-1b, granulocyte colony stimulating factor (GCSF), eotaxin, tumor necrosis factor (TNF), and monocyte chemoattractant protein 1 (MCP-1), were assessed in 45 newly diagnosed and untreated PD patients and in 44 control patients. Spearman's correlations were used to explore possible associations between CSF cytokines and clinical variables including mood. Benjamini-Hochberg (B-H) correction for multiple comparisons was applied. Linear regression was used to test significant associations correcting for other clinical variables. In PD patients, higher CSF concentrations of the inflammatory molecules IL-6, IL-9, IFNγ, and GCSF were found (all B-H corrected p < 0.02). Significant associations were found between BDI-II and the levels of IL-6 (Beta = 0.438; 95%CI 1.313-5.889; p = 0.003) and IL-8 (Beta = 0.471; 95%CI 0.185-0.743; p = 0.002). Positive associations were also observed between STAI-Y state and both IL-6 (Beta = 0.452; 95%CI 1.649-7.366; p = 0.003), and IL-12 (Beta = 0.417; 95%CI 2.238-13.379; p = 0.007), and between STAI-Y trait and IL-2 (Beta = 0.354; 95%CI 1.923-14.796; p = 0.012), IL-6 (Beta = 0.362; 95%CI 0.990-6.734; p = 0.01), IL-8 (Beta = 0.341; 95%CI 0.076-0.796; p = 0.019), IL-12 (Beta = 0.328; 95%CI 0.975-12.135; p = 0.023), and IL-17 (Beta = 0.334; 95CI 0.315-4.455; p = 0.025). An inflammatory CSF milieu may be associated with depression and anxiety in the early phases of PD, supporting a role of neuroinflammation in the pathogenesis of mood disturbances.

Neuroprotective effects of tetramethylpyrazine on spinal cord injury-Related neuroinflammation mediated by P2X7R/NLRP3 interaction.

OBJECTIVE: The inflammatory response is acknowledged as a crucial pathological aspect of spinal cord injury (SCI). Tetramethylpyrazine (TMP) has been demonstrated to possess neuroprotective properties within the central nervous system via its anti-inflammatory mechanisms. This study aims to investigate the molecular mechanism by which TMP alleviates SCI from an anti-inflammatory standpoint. METHODS: The SCI model was established using the MASCIS impactor device. The Basso-Beattie-Bresnahan (BBB) locomotor rating scale was utilised to assess rat locomotion. Nissl and Golgi staining were used to observe neuron and dendritic spine morphology, respectively. A transmission electron microscope was used to observe the microcosmic morphology of the axon. ELISA kits were used to measure the concentrations of IL-1ß and IL-18 in the spinal cord. Immunofluorescence staining was used to detect P2X7R+/IBA-1+ cells, and Western blot and RT-qPCR were used to analyze the protein and mRNA expression of P2X7R in the spinal cord. Additionally, Western blot was used to detect NLRP3 and Cleaved-Caspase-1 (p20), the critical proteins in the NLRP3 inflammasome pathway. RESULTS: TMP ameliorated the microcosmic morphology of the axon and had an inhibitory effect on the concentrations of IL-1ß and IL-18 after SCI. Furthermore, TMP inhibited the expression of both P2X7R and critical proteins of the NLRP3 inflammasome pathway on microglia after SCI. The aforementioned effects of TMP exhibit similarities to those of BBG (P2X7R antagonist); however, they can be effectively reversed by BzATP (P2X7R activator). CONCLUSION: TMP alleviated SCI via reducing tissue damage, neuroinflammation, and the expression of P2X7R, NLRP3, IL-1ß, and IL-18.

CD4 dim CD8 bright T cells are inversely associated with neuro-inflammatory markers among people with HIV.

OBJECTIVE: HIV-associated neuroinflammation persists in the brain despite suppressive combination antiretroviral therapy (cART). We evaluated associations between a subset of CD8 + T cells, termed CD4 dim CD8 bright T cells, and soluble markers of immune activation and/or neuroinflammation in the cerebrospinal fluid (CSF) and plasma of people with HIV (PWH). DESIGN: Fifteen cART-naive PWH were enrolled and underwent blood draw, lumbar puncture for CSF collection, and neuropsychological tests at week 0 (pre-cART) and 24 weeks after cART initiation. METHODS: CSF and peripheral blood T cells were evaluated with flow cytometry and soluble markers of immune activation were measured by multiplex and singleplex assays. Spearman bootstrap correlation coefficients with 10 000 resamples were computed and reported with corresponding 95% confidence intervals (CIs) for each marker of interest and T-cell type. RESULTS: The frequency of CSF CD4 dim CD8 bright T cells at week 0 was inversely related with CSF neopterin. In contrast, at week 24, CSF CD4 - CD8 + T cells were positively correlated with CSF s100ß, a marker of brain injury. In the blood, at week 0, CD4 dim CD8 bright T cells were inversely correlated with MCP-1, IP-10, IL-8, IL-6, G-CSF, and APRIL and positively correlated with plasma RANTES and MMP1. At week 0, the frequency of blood CD4 - CD8 + were positively correlated with CRP and BAFF. CONCLUSION: CD4 dim CD8 bright T cells are associated with some anti-inflammatory properties, whereas CD4 - CD8 + T cells may contribute to inflammation and injury. Assessing the contrast between these two cell populations in neuroHIV may inform targeted therapeutic intervention to reduce neuroinflammation and associated neurocognitive impairment.