Mesenchymal stromal cell treatment attenuates repetitive mild traumatic brain injury-induced persistent cognitive deficits via suppressing ferroptosis.

The incidence of repetitive mild traumatic brain injury (rmTBI), one of the main risk factors for predicting neurodegenerative disorders, is increasing; however, its underlying mechanism remains unclear. As suggested by several studies, ferroptosis is possibly related to TBI pathophysiology, but its effect on rmTBI is rarely studied. Mesenchymal stromal cells (MSCs), the most studied experimental cells in stem cell therapy, exert many beneficial effects on diseases of the central nervous system, yet evidence regarding the role of MSCs in ferroptosis and post-rmTBI neurodegeneration is unavailable. Our study showed that rmTBI resulted in time-dependent alterations in ferroptosis-related biomarker levels, such as abnormal iron metabolism, glutathione peroxidase (GPx) inactivation, decrease in GPx4 levels, and increase in lipid peroxidation. Furthermore, MSC treatment markedly decreased the aforementioned rmTBI-mediated alterations, neuronal damage, pathological protein deposition, and improved cognitive function compared with vehicle control. Similarly, liproxstatin-1, a ferroptosis inhibitor, showed similar effects. Collectively, based on the above observations, MSCs ameliorate cognitive impairment following rmTBI, partially via suppressing ferroptosis, which could be a therapeutic target for rmTBI.

Increased Microglial Exosomal miR-124-3p Alleviates Neurodegeneration and Improves Cognitive Outcome after rmTBI.

Repetitive mild traumatic brain injury (rmTBI) is considered to be an important risk factor for long-term neurodegenerative disorders such as Alzheimer's disease, which is characterized by ß-amyloid abnormalities and impaired cognitive function. Microglial exosomes have been reported to be involved in the transportation, distribution, and clearance of ß-amyloid in Alzheimer's disease. However, their impacts on the development of neurodegeneration after rmTBI are not yet known. The role of miRNAs in microglial exosomes on regulating post-traumatic neurodegeneration was investigated in the present study. We demonstrated that miR-124-3p level in microglial exosomes from injured brain was significantly altered in the acute, sub-acute, and chronic phases after rmTBI. In in vitro experiments, microglial exosomes with upregulated miR-124-3p (EXO-124) alleviated neurodegeneration in repetitive scratch-injured neurons. The effects were exerted by miR-124-3p targeting Rela, an inhibitory transcription factor of ApoE that promotes the ß-amyloid proteolytic breakdown, thereby inhibiting ß-amyloid abnormalities. In mice with rmTBI, the intravenously injected microglial exosomes were taken up by neurons in injured brain. Besides, miR-124-3p in the exosomes was transferred into hippocampal neurons and alleviated neurodegeneration by targeting the Rela/ApoE signaling pathway. Consequently, EXO-124 treatments improved the cognitive outcome after rmTBI, suggesting a promising therapeutic strategy for future clinical translation.

Exogenous IGF-1 improves tau pathology and neuronal pyroptosis in high-fat diet mice with cognitive dysfunction.

Insulin-like growth factor-1 (IGF-1) improves obesity-induced cognitive dysfunction, but its mechanism is not fully clarified. The aim of the study was to reveal whether IGF-1 treated cognitive dysfunction by improving tau pathology and neuronal pyroptosis in high-fat diet mice. During in vitro experiment, C57BL/6J mice were fed with high-fat diet, and were treated with PEG-IGF-1, IGF-1 receptor blocker AXL1717, HO-1 blocker Znpp IX or their combinations. Cognitive function was evaluated using Morris water maze. Expression of Nrf2, HO-1, p-tau, NLRP3, caspase-1 and IL-1ß in hippocampus was determined using western blotting. Pyroptosis rate in hippocampus was measured using flow cytometry. During in vivo experiment, HN-h cells were treated with palmitic acid, pyroptosis blocker nonecrosulfonamide or their combinations. The expression of the proteins and rate of pyroptosis were also measured using western blotting and flow cytometry. During in vitro experiment, high-fat diet mice showed cognitive dysfunction, significant hyperphosphorylation of tau protein and neuronal pyroptosis in hippocampus compared with the sham mice. After exogenous IGF-1 treatment, these abnormalities were reversed and Nrf2/HO-1 signaling pathway was activated. Inhibition of the signaling pathway using AXL1717 or Znpp IX re-deteriorated cognitive function, tau pathology and neuronal pyroptosis in hippocampus. During in vivo experiment, inhibition of pyroptosis using nonecrosulfonamide improved tau pathology in palmitic acid-treated HN-h cells. Exogenous IGF-1 improved tau pathology induced by high-fat diet through inhibition of neuronal pyroptosis and activation of Nrf2/HO-1 signaling pathway.

Hydrogen exerts neuroprotection by activation of the miR-21/PI3K/AKT/GSK-3ß pathway in an in vitro model of traumatic brain injury.

Few studies have explored the effect of hydrogen on neuronal apoptosis or impaired nerve regeneration after traumatic brain injury, and the mechanisms involved in these processes are unclear. In this study, we explored neuroprotection of hydrogen-rich medium through activation of the miR-21/PI3K/AKT/GSK-3ß pathway in an in vitro model of traumatic brain injury. Such model adopted PC12 cells with manual scratching. Then, injured cells were cultured in hydrogen-rich medium for 48 hours. Expression of miR-21, p-PI3K, p-Akt, p-GSK-3ß, Bax and Bcl-2 was measured using RT-qPCR, Western blot analysis and immunofluorescence staining. Rate of apoptosis was determined using TUNEL staining. Neuronal regeneration was assessed using immunofluorescence staining. The results showed that hydrogen-rich medium improved neurite regeneration and inhibited apoptosis in the injured cells. Scratch injury was accompanied by up-regulation of miR-21, p-PI3K, p-Akt and p-GSK-3ß. A miR-21 antagomir inhibited the expression of these four molecules, while a PI3K blocker only affected the three proteins and not miR-21. Both the miR-21 antagomir and PI3K blocker reversed the protective effect of hydrogen. In conclusion, hydrogen exerted a neuroprotective effect against neuronal apoptosis and impaired nerve regeneration through activation of miR-21/PI3K/AKT/GSK-3ß signalling in this in vitro model of traumatic brain injury.

A Design Space for Surfacing Content Recommendations in Visual Analytic Platforms.

Recommendation algorithms have been leveraged in various ways within visualization systems to assist users as they perform of a range of information tasks. One common focus for these techniques has been the recommendation of content, rather than visual form, as a means to assist users in the identification of information that is relevant to their task context. A wide variety of techniques have been proposed to address this general problem, with a range of design choices in how these solutions surface relevant information to users. This paper reviews the state-of-the-art in how visualization systems surface recommended content to users during users' visual analysis; introduces a four-dimensional design space for visual content recommendation based on a characterization of prior work; and discusses key observations regarding common patterns and future research opportunities.

Small extracellular vesicles as potential theranostic tools in central nervous system disorders.

Small extracellular vesicles(sEVs), a subset of extracellular vesicles with a bilateral membrane structure, contain biological cargoes, such as lipids, nucleic acids, and proteins. sEVs are crucial mediators of intercellular communications in the physiological and pathological processes of the central nervous system. Because of the special structure and complex pathogenesis of the brain, central nervous system disorders are characterized by high mortality and morbidity. Increasing evidence has focused on the potential of sEVs in clinical application for central nervous system disorders. sEVs are emerging as a promising diagnostic and therapeutic tool with high sensitivity, low immunogenicity, superior safety profile, and high transfer efficiency. This review highlighted the development of sEVs in central nervous system disorder clinical application. We also outlined the role of sEVs in central nervous system disorders and discussed the limitations of sEVs in clinical translation.

IL-33/ST2 Axis: A Potential Therapeutic Target in Neurodegenerative Diseases.

Interleukin 33 (IL-33) belongs to the IL-1 family and is localized in the nucleus. IL-33 is primarily composed of three distinct domains, namely the N-terminal domain responsible for nuclear localization, the intermediate sense protease domain, and the C-terminal cytokine domain. Its specific receptor is the suppression of tumorigenicity 2 (ST2), which is detected in serum-stimulated fibroblasts and oncogenes. While most other cytokines are actively produced in cells, IL-33 is passively produced in response to tissue damage or cell necrosis, thereby suggesting its role as an alarm following cell infection, stress, or trauma. IL-33 plays a crucial role in congenital and acquired immunity, which assists in the response to environmental stress and maintains tissue homeostasis. IL-33/ST2 interaction further produces many pro-inflammatory cytokines. Moreover, IL-33 is crucial for central nervous system (CNS) homeostasis and the pathogenic mechanisms underlying CNS degenerative disorders. The present work summarizes the structure of IL-33, its fundamental activities, and its role in immunoregulation and neurodegenerative diseases. Therefore, this work proposes that IL-33 may play a role in the pathogenic mechanism of diseases and can be used in the development of treatment strategies.

Intranasal Delivery of Gene-Edited Microglial Exosomes Improves Neurological Outcomes after Intracerebral Hemorrhage by Regulating Neuroinflammation.

Neural inflammatory response is a crucial pathological change in intracerebral hemorrhage (ICH) which accelerates the formation of perihematomal edema and aggravates neural cell death. Although surgical and drug treatments for ICH have advanced rapidly in recent years, therapeutic strategies that target and control neuroinflammation are still limited. Exosomes are important carriers for information transfer among cells. They have also been regarded as a promising therapeutic tool in translational medicine, with low immunogenicity, high penetration through the blood-brain barrier, and ease of modification. In our previous research, we have found that exogenous administration of miRNA-124-overexpressed microglial exosomes (Exo-124) are effective in improving post-injury cognitive impairment. From this, we evaluated the potential therapeutic effects of miRNA-124-enriched microglial exosomes on the ICH mice in the present study. We found that the gene-edited exosomes could attenuate neuro-deficits and brain edema, improve blood-brain barrier integrity, and reduce neural cell death. Moreover, the protective effect of Exo-124 was abolished in mice depleted of Gr-1+ myeloid cells. It suggested that the exosomes exerted their functions by limiting the infiltration of leukocyte into the brain, thus controlling neuroinflammation following the onset of ICH. In conclusion, our findings provided a promising therapeutic strategy for improving neuroinflammation in ICH. It also opens a new avenue for intranasal delivery of exosome therapy using miRNA-edited microglial exosomes.

Inhibition of Exosome Release Alleviates Cognitive Impairment After Repetitive Mild Traumatic Brain Injury.

BACKGROUND: Repetitive mild traumatic brain injury (rmTBI) is closely associated with chronic traumatic encephalopathy (CTE). Neuroinflammation and neuropathological protein accumulation are key links to CTE progression. Exosomes play important roles in neuroinflammation and neuropathological protein accumulation and spread. Here, we explored the role of brain-derived exosomes (BDEs) in mice with rmTBI and how the inhibition of BDE release contributes to neuroprotection. METHODS: GW4869 was used to inhibit exosome release, and behavioural tests, PET/CT and western blotting were conducted to explore the impact of this inhibition from different perspectives. We further evaluated cytokine expression by Luminex and microglial activation by immunofluorescence in mice with rmTBI after exosome release inhibition. RESULTS: Inhibition of BDE release reversed cognitive impairment in mice with rmTBI, enhanced glucose uptake and decreased neuropathological protein expression. Inhibition of BDE release also changed cytokine production trends and enhanced microglial proliferation. CONCLUSION: In this study, we found that BDEs are key factor in cognitive impairment in mice with rmTBI and that microglia are the main target of BDEs. Thus, inhibition of exosome release may be a new strategy for improving CTE prognoses.

Potential blood biomarkers for chronic traumatic encephalopathy: The multi-omics landscape of an observational cohort.

Chronic traumatic encephalopathy (CTE) is a neurodegenerative disease associated with exposure to repetitive head impacts, which is susceptible in elderly people with declined mobility, athletes of full contact sports, military personnel and victims of domestic violence. It has been pathologically diagnosed in brain donors with a history of repetitive mild traumatic brain injury (rmTBI), but cannot be clinically diagnosed for a long time. By the continuous efforts by neuropathologists, neurologists and neuroscientists in recent 10 years, an expert consensus for the diagnostic framework of CTE was proposed in 2021 funded by the National Institute of Neurological Disorders and Stroke. The new consensus contributes to facilitating research in the field. However, it still needs to incorporate in vivo biomarkers to further refine and validate the clinical diagnostic criteria. From this, a single-center, observational cohort study has been being conducted by Tianjin Medical University General Hospital since 2021. As a pilot study of this clinical trial, the present research recruited 12 pairs of gender- and age-matched rmTBI patients with healthy subjects. Their blood samples were collected for exosome isolation, and multi-omics screening to explore potential diagnostic biomarkers in blood and its exosomes. The expression level of CHL1 protein, KIF2A mRNA, LIN7C mRNA, miR-297, and miR-1183 in serum and exosomes were found to be differentially expressed between groups. Besides, serum and exosomal CHL1, KIF2A, and miR-1183, as well as exosomal miR-297 were further verified as potential biomarkers for CTE by low-throughput assays. They are expected to contribute to establishing a novel set of CTE diagnostic signatures with classic neurodegenerative indicators in our future study, thereby updating the consensus diagnostic criteria for CTE by incorporating new evidence of the in vivo biomarkers.

Modafinil Reduces Neuronal Pyroptosis and Cognitive Decline After Sleep Deprivation.

Sleep deprivation (SD) induces systemic inflammation that promotes neuronal pyroptosis. The purpose of this study was to investigate the effect of an antioxidant modafinil on neuronal pyroptosis and cognitive decline following SD. Using a mouse model of SD, we found that modafinil improved learning and memory, reduced proinflammatory factor (IL-1ß, TNF-α, and IL-6) production, and increased the expression of anti-inflammatory factors (IL-10). Modafinil treatment attenuated inflammasome activity and reduced neuronal pyroptosis involving the NLRP3/NLRP1/NLRC4-caspase-1-IL-1ß pathway. In addition, modafinil induced an upregulation of brain-derived neurotrophic factor (BDNF) and synaptic activity. These results suggest that modafinil reduces neuronal pyroptosis and cognitive decline following SD. These effects should be further investigated in future studies to benefit patients with sleep disorders.

Inhibition of miR-129 Improves Neuronal Pyroptosis and Cognitive Impairment Through IGF-1/GSK3ß Signaling Pathway: An In Vitro and In Vivo Study.

Pyroptosis is a programmed cell death process which is accompanied by inflammation. The aims of this in vitro and in vivo study were to reveal whether miR-129 contributed to neuronal pyroptosis and cognitive impairment and to further explore its mechanism involved. PC-12 cells were treated with LPS, miR-129 antagomir, AXL1717 (IGF-1 receptor blocker), or SB216763 (GSK3ß blocker). After that, expression of miR-129 was measured using qRT-PCR. Relationship between miR-129 and IGF-1 was revealed using luciferase reporter assay. Protein expression of IGF-1, p-Ser9-GSK3ß, NLRP3, and Caspase-1 was determined using western blotting. Pyroptosis rate was measured using flow cytometry. Wistar rats were fed with high-fat diet to induce neural inflammation and were further treated with miR-129 antagomir through intracerebroventricular injection. Then, cognitive impairment was assessed by water maze test. Expression of the proteins mentioned above was measured again in midbrain and hippocampus of the rats. In the PC-12 cells, LPS-induced neuronal pyroptosis can be alleviated by miR-129 antagomir. IGF-1 was a specific target for miR-129. Up-regulation and down-regulation of IGF-1/GSK3ß signaling pathway separately alleviated and deteriorated neuronal pyroptosis in the cells. In the rats, high-fat diet caused cognitive impairment following with neuronal pyroptosis and down-regulation of IGF-1/GSK3ß signaling pathway in midbrain and hippocampus tissues. Also, miR-129 antagomir improved these abnormalities in the rats. Inhibition of miR-129 improved neuronal pyroptosis and cognitive impairment through IGF-1/GSK3ß signaling pathway.

IGF-1 Alleviates Mitochondrial Apoptosis through the GSK3ß/NF-κB/NLRP3 Signaling Pathway in LPS-Treated PC-12 Cells.

Inflammation contributes to mitochondrial dysfunction and neuronal apoptosis. The aim of this study was to determine whether insulin-like growth factor-1 (IGF-1) alleviates mitochondrial apoptosis in lipopolysaccharide (LPS)-treated PC-12 cells, and to further explore the mechanism involved. Prepared PC-12 cells were treated with IGF-1, Mdivi-1 (DRP1 blocker), LY294002 (PI3K blocker), betulinic acid (NF-κB activator) or their combinations. Mitochondrial membrane potential and ATP generation were then measured to assess mitochondrial function. The rate of apoptosis was determined using flow cytometry. The expression of several apoptosis proteins (i.e. Bax, cleaved caspase-9 and cleaved caspase-3) and signaling proteins (i.e. p-GSK3ß, NF-κB and NLRP3) was measured using western blotting. Compared with the control cells, the LPS-treated cells showed evidence of mitochondrial dysfunction, increased apoptosis and upregulation of apoptosis proteins, which were significantly alleviated by Mdivi-1. These findings indicate that neuronal apoptosis was activated partly through the mitochondrial pathway. IGF-1 treatment inhibited mitochondrial apoptosis in a dose-dependent manner in the LPS-treated cells. The reagent also increased the expression of p-GSK3ß and decreased the expression of NF-κB and NLRP3. Both LY294002 and betulinic acid reversed the protective effect of IGF-1. In addition, LY294002 affected the expression of the three signaling proteins, while betulinic acid only affected the expression of NF-κB and NLRP3. These findings indicated a GSK3ß/NF-κB/NLRP3 signaling pathway was existed and was involved in the protective mechanism of IGF-1. In conclusion, IGF-1 alleviated mitochondrial apoptosis through GSK3ß/NF-κB/NLRP3 signaling pathway in LPS-treated PC-12 cells.

Mesenchymal stem cell-derived exosome: a promising alternative in the therapy of Alzheimer's disease.

Alzheimer's disease (AD) has been a devastating public health with the development of global aging. Approaches for reducing the current AD epidemic are becoming a primary focus of human healthcare due to the lack of achieved lasting and complete remission strategies to treat AD with the characteristics of heterogeneity and complexity. Exosomes, which is the new emerging approach to intercellular communication, provide novel perspective on identified therapeutic strategies of AD. Mesenchymal stem cell-derived exosomes (MSC-exos) are emerging to be an appealing therapeutic tool for AD, with the donor-derived properties and the characteristics of minimal immunogenicity, effortless storage, nature delivery vehicles, and low risks of tumor formation based on the previous researches. In this review, we elaborate the mechanism of MSC-exos in the treatment of AD and discuss limitations in the clinical application.