ASN NEURO最新文献

The mechanisms that govern whether T cells cross blood-brain barrier (BBB) endothelium by transcellular versus paracellular routes are unclear. Caveolin-1 is a membrane scaffolding and signaling protein associated with transcellular transmigration through the endothelial cytoplasm. Here, we report that the neuroinflammatory chemokine CXCL10 induced transcellular, caveolar transmigration of CXCR3+ CD4+ T cells. Specifically, data revealed that CXCL10-induced transcellular transmigration requires expression of Caveolin-1 and ICAM-1 in brain endothelial cells and of the CXCL10 receptor, CXCR3, and LFA-1 in T cells. Moreover, Caveolin-1 promoted CXCL10 aggregation into brain endothelial cytoplasmic stores, providing a mechanism for activation and recruitment of CXCR3+ T cells to migrate at cytoplasmic locations, distal to cell-cell junctions. Consistent with our in vitro data, genetic ablation of Caveolin-1 reduces infiltration of CXCR3+ CD4+ T cells into the CNS in experimental autoimmune encephalomyelitis. Our findings establish a novel mechanism by which brain endothelial cells utilize Caveolin-1 dependent CXCL10 intracellular stores to license T cells for transcellular migration across the blood-brain barrier.

People living with HIV (PLWH) experience HIV-associated neurocognitive disorders (HAND), even though combination antiretroviral therapy (cART) suppresses HIV replication. HIV-1 transactivator of transcription (HIV-1 Tat) contributes to the development of HAND through neuroinflammatory and neurotoxic mechanisms. C-C chemokine 5 receptor (CCR5) is important in immune cell targeting and is a co-receptor for HIV viral entry into CD4+ cells. Notably, CCR5 has been implicated in cognition unrelated to HIV infection. Inhibition of CCR5 has been shown to improve learning and memory. To test whether CCR5 is involved in cognitive changes in HAND, we used a non-infectious, transgenic model in which HIV-1 Tat is inducibly expressed. Well-powered cohorts of male and female mice were placed on a diet containing doxycycline to induce Tat expression for 8-wks. Males showed Tat-mediated deficits in the Barnes maze test of spatial learning and memory; females showed no impairments. Deficits in the males were fully reversed by the CCR5 antagonist, maraviroc (MVC). Tat-mediated deficits were not found in novel object recognition or contextual fear conditioning in either sex. Based on earlier work, we hypothesized that MVC might increase brain-derived neurotrophic factor (BDNF), which is essential in maintaining synaptodendritic function. MVC did increase the mBDNF to proBDNF ratio in males, perhaps contributing to improved cognition.

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that affects more than 50 million people worldwide. One of the hallmark features of AD is the accumulation of amyloid β-peptide (Aβ) protein in the brain. P-glycoprotein (P-gp) is a membrane-bound protein expressed in various tissues, including the cerebrovascular endothelium. It plays a crucial role in the efflux of toxic substances, including Aβ, from the brain. Aberrations in P-gp levels or activity have been implicated in the pathogenesis of AD by promoting the accumulation of Aβ in the brain. Therefore, modulating the P-gp function represents a promising therapeutic strategy for treating AD. P-gp has multiple substrate binding sites, creating the potential for substrates to fall into complementation groups based on these sites; two substrates in the same complementation group may compete with one other, but two substrates in different groups may exhibit cooperativity. Thus, a given P-gp substrate may interfere with Aβ efflux whereas another may promote clearance. These threats and opportunities, as well as other aspects of P-gp relevance to AD, are discussed here.

Proliferation of microglia represents a physiological process, which is accelerated in several neurodegenerative disorders including Alzheimer disease (AD). The effect of such neurodegeneration-associated microglial proliferation on function and disease progression remains unclear. Here, we show that proliferation results in profound alterations of cellular function by providing evidence that newly proliferated microglia show impaired beta-amyloid clearance in vivo. Through sorting of proliferating microglia of APP/PS1 mice and subsequent transcriptome analysis, we define unique proliferation-associated transcriptomic signatures that change with age and beta-amyloid accumulation and are characterized by enrichment of immune system-related pathways. Of note, we identify the DEAD-Box Helicase 3 X-Linked (DDX3X) as a key molecule to modulate microglia activation and cytokine secretion and it is expressed in the AD brain. Together, these results argue for a novel concept by which phenotypic and functional microglial changes occur longitudinally as a response to accelerated proliferation in a neurodegenerative environment.

Fragile X Syndrome (FXS) is a leading genetic cause of intellectual disability and autism-like behaviors. Glutamatergic mGluR5 receptors and matrix metalloproteinase-9 (MMP-9) are therapeutic targets to treat FXS, but clinical trials targeting each of these pathways have not been successful. Here, we tested if the electroencephalography (EEG) phenotypes associated with FXS are reversed with a novel combination of treatments affecting the two pathways. Fmr1 knockout (KO) mice were given 10 days of CTEP (mGluR5 antagonist) alone or in combination with minocycline (MMP-9 inhibitor). EEG was recorded during resting (no acoustic stimulation) and during sound presentations (to produce sound-evoked EEG) at 1 day and 10 days after the beginning of treatment administration to test acute effects and potential tachyphylaxis. In pre-treatment WT and KO mice comparisons, we replicated previously published Fmr1 KO mouse EEG phenotypes including elevated power in the resting gamma band, elevated single trial power, and reduced phase-locking to spectrotemporally dynamic auditory stimuli. We found that CTEP treatment alone did not show any benefit compared to vehicle in Fmr1 KO mice after either 1 or 10 days of treatment. CTEP + minocycline reduced resting gamma band power in the Fmr1 KO mice to a greater extent than vehicle at both treatment time points. There were no effects on sound-evoked responses. These data suggest that combined CTEP and minocycline treatment alters resting EEG measures while each treatment administered separately does not yield similar changes. High power in broadband gamma frequency correlates with irritability, stereotyped behaviors, and hyperactivity in FXS patients, suggesting a combination of drugs that reduce mGluR5 and MMP-9 activity may be beneficial in FXS.

Previous studies have shown that lanthionine ketimine ethyl ester (LKE) reduces clinical scores in the experimental autoimmune encephalomyelitis (EAE) mouse model of Multiple Sclerosis, induces differentiation of oligodendrocyte progenitor cells (OPCs) in vitro, and accelerates remyelination following cuprizone induced demyelination. In a search for derivatives with greater efficacy to induce OPC maturation or proliferation, we screened a panel of 2-alkyl and 3-phosphonate substituted LK derivatives. Incubation of Oli-neu oligodendrocyte cells with 2-n-butyl- or 2-n-hexyl-LKE-phosphonate reduced spontaneous cell death, increased proliferation, and increased maturation. These were associated with changes in corresponding mRNA levels of Olig2, PLP, and O4. These derivatives also reduced cell death and increased proliferation and maturation in primary mouse OPCs. The increased hydrophobicity of these derivatives suggests these will be better candidates for testing effects in animal models of Multiple Sclerosis and other demyelinating diseases.

Long-term effects of alcohol-related brain damage (ARBD) include neurocognitive and neurobehavioral dysfunctions with neurodegeneration. White matter (WM) is notably targeted across the lifespan yet relatively little is known about the stages, mechanisms, and consequences of myelin and axonal loss. In alcohol-related liver disease, early pathology is reversible, but with chronic heavy alcohol exposures, disease progresses with degeneration, and ultimately organ failure. Similarly, WM ARBD also develops in two broad stages. The early stages of WM ARBD are likely mediated by vascular dysfunction with tissue swelling, oligodendrocyte dysfunction, myelin loss, neuroinflammation, and oxidative stress. The chronic progressive stage is linked to metabolic dysfunction related to impairments in insulin and insulin-like growth factor signaling through Akt-mechanistic target of rapamycin (mTOR) pathways that mediate oligodendrocyte survival and function, myelin homeostasis, and blood-brain-barrier (BBB) integrity. We hypothesize that early-stage WM ARBD may be largely reversible by abstinence and anti-oxidant/anti-inflammatory measures, whereas late-stage ARBD requires strategies to restore WM/oligodendrocyte metabolic function via insulin sensitizer, antioxidant, anti-inflammatory, and myelin homeostasis/normalization support. Multi-pronged, overlapping but distinct therapeutic strategies are needed to reduce the impact and long-term health consequences of chronic progressive WM ARBD.

Parkinson's disease is the second most prevalent neurodegenerative disorder and is characterized by the degeneration of dopaminergic neurons. Significant improvements in gait balance, particularly in step length and velocity, were observed with less invasive wireless cortical stimulation. Transcriptome sequencing was performed to demonstrate the cellular mechanism, specifically targeting the primary motor cortex, where stimulation was applied. Our findings indicated that 38 differentially expressed genes (DEGs), initially downregulated following Parkinson's disease induction, were subsequently restored to normal levels after cortical stimulation. These 38 DEGs are potential targets for the treatment of motor disorders in Parkinson's disease. These genes are implicated in crucial processes, such as astrocyte-mediated blood vessel development and microglia-mediated phagocytosis of damaged motor neurons, suggesting their significant roles in improving behavioral disorders. Moreover, these biomarkers not only facilitate the rapid and accurate diagnosis of Parkinson's disease but also assist in precision medicine approaches.

Maintaining optimal brain metabolism supports neuronal function, synaptic communication, and cognitive processes. During ischemic stroke, brain metabolism and cellular bioenergetics within the neurovascular unit are disrupted, emphasizing the significance of understanding the physiology and pathology of the stroke brain. The objective of this study was to quantify and compare phase-dependent changes in glycolysis and oxidative phosphorylation following ischemic stroke by using the Seahorse XFe24 Analyzer. Since there are limited established methods to quantify glycolytic activity in brain tissue, we optimized the accuracy and reproducibility of extracellular acidification rate (ECAR) measurement by increasing the incubation time following exposure to each reagent. Following optimization, we quantified both ECAR and the oxygen consumption rate (OCR), a measure of oxidative phosphorylation, in cortical brain tissue punches corresponding to the penumbra from mice subjected to ischemic stroke. ECAR and OCR were quantified in tissue punches from the injured (ipsilateral) and the non-injured (contralateral) hemispheres at 48 hours, 7 days, and 14 days post-stroke. Normalized ECAR measurements showed elevated glycolytic activity in the ipsilateral and contralateral hemispheres at 7 days post-stroke compared to other time points. In contrast, normalized OCR measurements showed a modest increase in basal respiration within the ipsilateral hemispheres between 48 hours and 14 days post-stroke. In summary, the results demonstrate that ischemic stroke results in a distinct phase-dependent metabolic phenotype in both cortical hemispheres that persists up to 14 days after injury.

Hexanucleotide repeat expansion (HRE) in the non-coding region of the gene C9orf72 is the most prevalent mutation in amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). The C9orf72 HRE contributes to neuron degeneration in ALS/FTD through both cell-autonomous mechanisms and non-cell autonomous disease processes involving glial cells such as microglia. The molecular mechanisms underlying the contribution of C9orf72-HRE microglia to neuron death in ALS/FTD remain to be fully elucidated. In this study, we generated microglia from human C9orf72-HRE and isogenic iPSCs using three different microglia derivation methods. RNA sequencing analysis reveals a cell-autonomous dysregulation of extracellular matrix (ECM) genes and genes involved in pathways underlying inflammasome activation in C9orf72-HRE microglia. In agreement with elevated expression of inflammasome components, conditioned media from C9orf72-HRE microglia enhance the death of C9orf72-HRE motor neurons implicating microglia-secreted molecules in non-cell autonomous mechanisms of C9orf72 HRE pathology. These findings suggest that aberrant activation of inflammasome-mediated mechanisms in C9orf72-HRE microglia results in a pro-inflammatory phenotype that contributes to non-cell autonomous mechanisms of motor neuron degeneration in ALS/FTD.