Regulation of therapeutic hypothermia on inflammatory cytokines, microglia polarization, migration and functional recovery after ischemic stroke in mice

Tirofiban mediates neuroprotective effects in acute ischemic stroke by reducing inflammatory response

Growing evidence suggests that neuroinflammation is a critical driver of the development, worsening, and cell death observed in acute ischemic stroke (AIS). While prior research has demonstrated that tirofiban enhances functional recovery in AIS patients by suppressing platelet aggregation, its impact and underlying mechanisms in AIS-related neuroinflammation remain elusive. The current study established an AIS mouse model employing photochemical techniques and assessed neurological function and brain infarct size using the modified neurological severity scale (mNSS) and 2,3,5-Triphenyltetrazolium chloride (TTC) staining, respectively. Tirofiban significantly reduced the volume of cerebral infarction in AIS mice, accompanied by an enhancement in their neurological functions. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assays along with experiments assessing oxidative stress showed that tirofiban mitigated oxidative damage and apoptosis in the ischemic penumbra post-AIS. Additionally, DNA microarray analysis revealed alterations in gene expression patterns in the ischemic penumbra after tirofiban treatment. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that most gene-level downregulated signaling pathways were closely related to the inflammatory response. Moreover, the protein microarray analysis revealed that tirofiban diminished the expression levels of inflammatory cytokines, such as interleukin-1 (IL-1), IL-6, and tumor necrosis factor-alpha, in the ischemic penumbra. Additionally, immunofluorescence staining showed that tirofiban regulated inflammatory responses by altering the state and phenotype of microglia. In conclusion, this study suggests that tirofiban reduces inflammatory response by regulating microglial state and phenotype and lowering the levels of inflammatory factors, providing neuroprotection in acute ischemic stroke.

Temperature control during pars plana vitrectomy

PURPOSE

To evaluate the impact of temperature-controlled pars plana vitrectomy (PPV) on structural and functional outcomes in a rabbit eye model in vivo.

METHODS

Ten healthy New Zealand White rabbits underwent temperature-controlled PPV in the right eye (group A), using a device specifically designed to heat the infusion fluid/air and integrated into the vitrectomy machine, and conventional PPV in the left eye (group B). Both eyes received ophthalmic examination and electroretinography (ERG) before and 1 week postoperatively. After 1-week ERG, rabbits were enucleated and then sacrificed. Histological and immunohistochemical examinations were performed on enucleated eyes and expression of glial fibrillary acidic protein (GFAP) and vimentin investigated.

RESULTS

Postoperatively, only group B showed significantly decreased amplitude and increased latency of a-wave at 3 cd·s/m2 (p = 0.001 and 0.005, respectively). Significant increase of b-wave latency at 0.01 cd·s/m2 was detected in both groups (p = 0.019 and 0.023, respectively). Postoperatively, amplitude of oscillatory potentials (OPs) increased significantly in group A (p = 0.023) and decreased in group B. In both groups, OPs latency significantly increased at 1-week test (P < 0.05). A greater number of eyes without structural retinal alterations was detected in group A compared to group B (6 vs 5, respectively). GFAP expression was higher in group B than group A, even if the difference was not statistically significant.

CONCLUSION

Temperature-controlled PPV resulted in more favorable functional and structural outcomes in rabbit eyes compared with conventional PPV, supporting the potential beneficial role of the intraoperative management of intraocular temperature in vitreoretinal surgery.

Facile engineered macrophages-derived exosomes-functionalized PLGA nanocarrier for targeted delivery of dual drug formulation against neuroinflammation by modulation of microglial polarization in a post-stroke depression rat model

Post-stroke depression (POSD) is a common difficulty and most predominant emotional syndrome after stroke often consequences in poor outcomes. In the present investigation, we have designed and studied the neurologically active celastrol/minocycline encapsulated with macrophages-derived exosomes functionalized PLGA nanoformulations (CMC-EXPL) to achieve enhanced anti-inflammatory behaviour and anti-depressant like activity in a Rat model of POSD. The animal model of POSD was established through stimulating process with chronic unpredictable mild stress (CUM) stimulations after procedure of middle cerebral artery occlusion (MCAO). Neuronal functions and Anti-inflammation behaviours were observed by histopathological (H&E) examination and Elisa analyses, respectively. The anti-depressive activity of the nanoformulations treated Rat models were evaluated by open-field and sucrose preference test methods. Microglial polarization was evaluated via flow-cytometry and qRT-PCR observations. The observed results exhibited that prepared nanoformulations reduced the POSD-stimulated depressive-like activities in rat models as well alleviated the neuronal damages and inflammatory responses in the cerebral hippocampus. Importantly, prepared CMC-EXPL nanoformulation effectively prevented the M1 pro-inflammatory polarization and indorsed M2 anti-inflammatory polarization, which indicates iNOS and CD86 levels significantly decreased and upsurged Arg-1 and CD206 levels. CMC-EXPL nanoformulation suggestively augmented anti-depressive activities and functional capability and also alleviated brain inflammation in POSD rats, demonstrating its therapeutic potential for POSD therapy.

Novel Therapeutic Mechanisms and Strategies for Intracerebral Hemorrhage: Focusing on Exosomes

Intracerebral hemorrhage (ICH) is a primary, non-traumatic cerebral event associated with substantial mortality and disability. Despite advancements in understanding its etiology and refining diagnostic techniques, a validated treatment to significantly improve ICH prognosis remains elusive. Exosomes, a subtype of extracellular vesicles, encapsulate bioactive components, predominantly microRNAs (miRNAs), facilitating and regulating intercellular communication. Currently, exosomes have garnered considerable interests in clinical transformation for their nanostructure, minimal immunogenicity, low toxicity, inherent stability, and the ability to traverse the blood-brain barrier. A wealth of studies has demonstrated that exosomes can improve the prognosis of ICH through anti-apoptosis, neurogenesis, angiogenesis, anti-inflammation, immunomodulation, and autophagy, primarily via the transportation or overexpression of selected miRNAs. More importantly, exosomes can be easily customized with specific miRNAs or bioactive compounds to establish delivery systems, broadening their potential applications. This review focuses on the therapeutic potential of exosomes in ICH, reviewing the mechanisms of molecular biology mediated by certain miRNAs, discussing the benefits, challenges, and future prospects in ICH treatment. We hope comprehensive understanding of exosomes based on miRNAs will provide new insights into the treatment of ICH and guide the translation of exosome's research from laboratory to clinical practice.

Application of artificial hibernation technology in acute brain injury

Controlling intracranial pressure, nerve cell regeneration, and microenvironment regulation are the key issues in reducing mortality and disability in acute brain injury. There is currently a lack of effective treatment methods. Hibernation has the characteristics of low temperature, low metabolism, and hibernation rhythm, as well as protective effects on the nervous, cardiovascular, and motor systems. Artificial hibernation technology is a new technology that can effectively treat acute brain injury by altering the body's metabolism, lowering the body's core temperature, and allowing the body to enter a state similar to hibernation. This review introduces artificial hibernation technology, including mild hypothermia treatment technology, central nervous system regulation technology, and artificial hibernation-inducer technology. Upon summarizing the relevant research on artificial hibernation technology in acute brain injury, the research results show that artificial hibernation technology has neuroprotective, anti-inflammatory, and oxidative stress-resistance effects, indicating that it has therapeutic significance in acute brain injury. Furthermore, artificial hibernation technology can alleviate the damage of ischemic stroke, traumatic brain injury, cerebral hemorrhage, cerebral infarction, and other diseases, providing new strategies for treating acute brain injury. However, artificial hibernation technology is currently in its infancy and has some complications, such as electrolyte imbalance and coagulation disorders, which limit its use. Further research is needed for its clinical application.

Bibliometric insights into the inflammation and mitochondrial stress in ischemic stroke

BACKGROUND

Research in the areas of inflammation and mitochondrial stress in ischemic stroke is rapidly expanding, but a comprehensive overview that integrates bibliometric trends with an in-depth review of molecular mechanisms is lacking.

OBJECTIVE

To map the evolving landscape of research using bibliometric analysis and to detail the molecular mechanisms that underpin these trends, emphasizing their implications in ischemic stroke.

METHODS

We conducted a bibliometric analysis to identify key trends, top contributors, and focal research themes. In addition, we review recent research advances in mitochondrial stress and inflammation in ischemic stroke to gain a detailed understanding of the pathophysiological processes involved.

CONCLUSION

Our integrative approach not only highlights the growing research interest and collaborations but also provides a detailed exploration of the molecular mechanisms that are central to the pathology of ischemic stroke. This synthesis offers valuable insights for researchers and paves the way for targeted therapeutic interventions.

Isobavachalcone alleviates ischemic stroke by suppressing HDAC1 expression and improving M2 polarization

Ischemic stroke is a serious cerebrovascular condition. Isobavachalcone (ISO) has been documented to exhibit an anti-inflammatory effect across a variety of diseases; however, its protective impact on ischemic stroke remains unexplored. In this study, we evaluated the influence of ISO in both transient middle cerebral artery occlusion/reperfusion (tMCAO/R) rat models and oxygen-glucose deprivation/reperfusion (OGD/R) cell models. We observed that pretreatment with 50 mg/kg ISO diminished the volume of brain infarction, reduced brain edema, and ameliorated neurological deficits in rats. A reduction in Nissl bodies was noted in the tMCAO/R group, which was reversed following treatment with 50 mg/kg ISO. TUNEL/NeuN double staining revealed a decrease in TUNEL-positive cells in tMCAO/R rats treated with ISO. Furthermore, ISO treatment suppressed the expression of cleaved caspase-3 and BAX, while elevating the expression of BCL-2 in tMCAO/R rats. The levels of CD86 and iNOS were elevated in tMCAO/R rats; conversely, ISO treatment enhanced the expression of CD206 and Arg-1. Additionally, the expression of TNF-α, IL-6, and IL-1β was elevated in tMCAO/R rats, whereas ISO treatment counteracted this effect. ISO treatment also increased the expression of TGF-β and IL-10 in the ischemic penumbra of tMCAO/R rats. It was found that ISO treatment hindered microglial M1 polarization and favored M2 polarization. Histone Deacetylase 1 (HDAC1) is the downstream target protein of ISO, with ISO treatment resulting in decreased HDAC1 expression in both tMCAO/R rats and OGD/R-induced cells. Overexpression of HDAC1 was shown to promote microglial M1 polarization and inhibit M2 polarization in OGD/R+ISO cells. Overall, ISO treatment mitigated brain damage following ischemic stroke by promoting M2 polarization and attenuated ischemic injury by repressing HDAC1 expression.

Bioactive materials from berberine-treated human bone marrow mesenchymal stem cells promote alveolar bone regeneration by regulating macrophage polarization

Alveolar bone regeneration has been strongly linked to macrophage polarization. M1 macrophages aggravate alveolar bone loss, whereas M2 macrophages reverse this process. Berberine (BBR), a natural alkaloid isolated and refined from Chinese medicinal plants, has shown therapeutic effects in treating metabolic disorders. In this study, we first discovered that culture supernatant (CS) collected from BBR-treated human bone marrow mesenchymal stem cells (HBMSCs) ameliorated periodontal alveolar bone loss. CS from the BBR-treated HBMSCs contained bioactive materials that suppressed the M1 polarization and induced the M2 polarization of macrophages in vivo and in vitro. To clarify the underlying mechanism, the bioactive materials were applied to different animal models. We discovered macrophage colony-stimulating factor (M-CSF), which regulates macrophage polarization and promotes bone formation, a key macromolecule in the CS. Injection of pure M-CSF attenuated experimental periodontal alveolar bone loss in rats. Colony-stimulating factor 1 receptor (CSF1R) inhibitor or anti-human M-CSF (M-CSF neutralizing antibody, Nab) abolished the therapeutic effects of the CS of BBR-treated HBMSCs. Moreover, AKT phosphorylation in macrophages was activated by the CS, and the AKT activator reversed the negative effect of the CSF1R inhibitor or Nab. These results suggest that the CS of BBR-treated HBMSCs modulates macrophage polarization via the M-CSF/AKT axis. Further studies also showed that CS of BBR-treated HBMSCs accelerated bone formation and M2 polarization in rat teeth extraction sockets. Overall, our findings established an essential role of BBR-treated HBMSCs CS and this might be the first report to show that the products of BBR-treated HBMSCs have active effects on alveolar bone regeneration.

Mild hypothermia reduces lipopolysaccharide-induced microglial activation via down-regulation of Tent5c

Microglial activation is a critical factor in the pathogenesis and progression of neuroinflammatory diseases. Mild hypothermia, known for its neuroprotective properties, has been shown to alleviate microglial activation. In this study, we explore the differentially expressed (DE) mRNAs and long non-coding RNAs (lncRNAs) in BV-2 microglial cells under different conditions: normal temperature (CN), mild hypothermia (YT), normal temperature with lipopolysaccharide (LPS), and mild hypothermia with LPS (LPS + YT). Venn analysis revealed 119 DE mRNAs that were down-regulated in the LPS + YT vs LPS comparison but up-regulated in the CN vs LPS comparison, primarily enriched in Gene Ontology terms related to immune and inflammatory responses. Furthermore, through Venn analysis of YT vs CN and LPS + YT vs LPS comparisons, we identified 178 DE mRNAs and 432 DE lncRNAs. Among these transcripts, we validated the expression of Tent5c at the protein and mRNA levels. Additionally, siRNA-knockdown of Tent5c attenuated the expression of pro-inflammatory genes (TNF-α, IL-1β, Agrn, and Fpr2), cellular morphological changes, NLRP3 and p-P65 protein levels, immunofluorescence staining of p-P65 and number of cells with ASC-speck induced by LPS. Furthermore, Tent5c overexpression further potentiated the aforementioned indicators in the context of mild hypothermia with LPS treatment. Collectively, our findings highlight the significant role of Tent5c down-regulation in mediating the anti-inflammatory effects of mild hypothermia.

Impact of immediate postrecanalization cooling on outcome in acute ischemic stroke patients with a large ischemic core: prospective cohort study

BACKGROUND

Patients with large acute ischemic strokes (AIS) often have a poor prognosis despite successful recanalization due to multiple factors including reperfusion injury. The authors aim to describe our preliminary experience of endovascular cooling in patients with a large AIS after recanalization.

METHODS

From January 2021 to July 2022, AIS patients presenting with large infarcts (defined as ASPECTS ≤5 on noncontrast CT or ischemic core ≥50 ml on CT perfusion) who achieved successful recanalization after endovascular treatment were analyzed in a prospective registry. Patients were divided into targeted temperature management (TTM) and non-TTM group. Patients in the TTM group received systemic cooling with a targeted core temperature of 33° for at least 48 h. The primary outcome is 90-day favorable outcome [modified Rankin Scale (mRS) 0-2]. The secondary outcomes are 90-day good outcome (mRS 0-3), mortality, intracranial hemorrhage and malignant cerebral edema within 7 days or at discharge.

RESULTS

Forty-four AIS patients were recruited (15 cases in the TTM group and 29 cases in the non-TTM group). The median Alberta Stroke Program Early CT Score (ASPECTS) was 3 (2-5). The median time for hypothermia duration was 84 (71.5-147.6) h. The TTM group had a numerically higher proportion of 90-day favorable outcomes than the non-TTM group (46.7 vs. 27.6%, P=0.210), and no significant difference were found regarding secondary outcomes (all P>0.05). The TTM group had a numerically higher rates of pneumonia (66.7 vs. 58.6%, P=0.604) and deep vein thrombosis (33.3 vs. 13.8%, P=0.138). Shivering occurred in 4/15 (26.7%) of the TTM patients and in none of the non-TTM patients (P=0.009).

CONCLUSIONS

Postrecanalization cooling is feasible in patients with a large ischemic core. Future randomized clinical trials are warranted to validate its efficacy.

Hypothermia and temperature modulation for intracerebral hemorrhage (ICH): pathophysiology and translational applications

Background

Intracerebral hemorrhage (ICH) still poses a substantial challenge in clinical medicine because of the high morbidity and mortality rate that characterizes it. This review article expands into the complex pathophysiological processes underlying primary and secondary neuronal death following ICH. It explores the potential of therapeutic hypothermia as an intervention to mitigate these devastating effects.

Methods

A comprehensive literature review to gather relevant studies published between 2000 and 2023.

Discussion

Primary brain injury results from mechanical damage caused by the hematoma, leading to increased intracranial pressure and subsequent structural disruption. Secondary brain injury encompasses a cascade of events, including inflammation, oxidative stress, blood-brain barrier breakdown, cytotoxicity, and neuronal death. Initial surgical trials failed to demonstrate significant benefits, prompting a shift toward molecular mechanisms driving secondary brain injury as potential therapeutic targets. With promising preclinical outcomes, hypothermia has garnered attention, but clinical trials have yet to establish its definitive effectiveness. Localized hypothermia strategies are gaining interest due to their potential to minimize systemic complications and improve outcomes. Ongoing and forthcoming clinical trials seek to clarify the role of hypothermia in ICH management.

Conclusion

Therapeutic hypothermia offers a potential avenue for intervention by targeting the secondary injury mechanisms. The ongoing pursuit of optimized cooling protocols, localized cooling strategies, and rigorous clinical trials is crucial to unlocking the potential of hypothermia as a therapeutic tool for managing ICH and improving patient outcomes.

Hypothermia is Associated with Improved Neurological Outcomes After Mechanical Thrombectomy

BACKGROUND

Acute ischemic stroke (AIS) is the second leading cause of death globally. Mechanical thrombectomy (MT) has improved patient prognosis but expedient treatment is still necessary to minimize anoxic injury. Lower intraoperative body temperature decreases cerebral oxygen demand, but the role of hypothermia in treatment of AIS with MT is unclear.

METHODS

We retrospectively reviewed patients undergoing MT for AIS from 2014 to 2020 at our institution. Patient demographics, comorbidities, intraoperative parameters, and outcomes were collected. Maximum body temperature was extracted from minute-by-minute anesthesia readings, and patients with maximal temperature below 36°C were considered hypothermic. Risk factors were assessed by χ2 and multivariate ordinal regression.

RESULTS

Of 68 patients, 27 (40%) were hypothermic. There was no significant association of hypothermia with patient age, comorbidities, time since last known well, number of passes intraoperatively, favorable revascularization, tissue plasminogen activator use, and immediate postoperative complications. Hypothermic patients exhibited better neurologic outcome at 3-month follow-up (P = 0.02). On multivariate ordinal regression, lower maximum intraoperative body temperature was associated with improved 3-month outcomes (P < 0.001), when adjusting for other factors influencing neurological outcomes. Other significant protective factors included younger age (P = 0.03), better revascularization (P = 0.03), and conscious sedation (P = 0.02).

CONCLUSIONS

Lower intraoperative body temperature during MT was independently associated with improved neurological outcome in this single center retrospective series. These results may help guide clinicians in employing therapeutic hypothermia during MT to improve long-term neurologic outcomes from AIS, although larger studies are needed.

Low-dose ionizing radiation promotes motor recovery and brain rewiring by resolving inflammatory response after brain injury and stroke

Traumatic brain injury (TBI) and stroke share a common pathophysiology that worsens over time due to secondary tissue injury caused by sustained inflammatory response. However, studies on pharmacological interventions targeting the complex secondary injury cascade have failed to show efficacy. Here, we demonstrated that low-dose ionizing radiation (LDIR) reduced lesion size and reversed motor deficits after TBI and photothrombotic stroke. Magnetic resonance imaging demonstrated significant reduction of infarct volume in LDIR-treated mice after stroke. Systems-level transcriptomic analysis showed that genes upregulated in LDIR-treated stoke mice were enriched in pathways associated with inflammatory and immune response involving microglia. LDIR induced upregulation of anti-inflammatory- and phagocytosis-related genes, and downregulation of key pro-inflammatory cytokine production. These findings were validated by live-cell assays, in which microglia exhibited higher chemotactic and phagocytic capacities after LDIR. We observed substantial microglial clustering at the injury site, glial scar clearance and reversal of motor deficits after stroke. Cortical microglia/macrophages depletion completely abolished the beneficial effect of LDIR on motor function recovery in stroke mice. LDIR promoted axonal projections (brain rewiring) in motor cortex and recovery of brain activity detected by electroencephalography recordings months after stroke. LDIR treatment delayed by 8 h post-injury still maintained full therapeutic effects on motor recovery, indicating that LDIR is a promising therapeutic strategy for TBI and stroke.

Microglia play an important role in PRV infection-induced immune responses of the central nervous system

Pseudorabies virus (PRV) can infect multiple hosts and lead to fatal encephalitis. There is a significant increase in the number of microglia in the brain of animals infected with PRV. However, whether and how microglia contribute to central nervous system damage in PRV infection remain unknown. In the present study, we elucidated that PRV infection can cause more severe inflammatory cell infiltration, thicker and more numerous vessel sleeve walls, and more severe inflammatory responses in the brains of natural hosts (pigs) than in those of nonnatural hosts (mice). In a mice infection model, activated microglia restricted viral replication in the early stage of infection. Acute neuroinflammation caused by microglia hyperactivation at late-stage of infection. Furthermore, in vitro experiments revealed that microglia restricted viral replication and decreased viral infectivity. This may be associated with the phagocytic ability of microglia because we observed a significant increase in the expression of the membrane receptor TREM2 in microglia, which is closely related to phagocytosis, we observed that depletion of microglia exacerbated neurological symptoms, blood-brain barrier breakdown, and peripheral lymphocyte infiltration. Taken together, we revealed the dual role of microglia in protecting the host and neurons from PRV infection.

Bioinformatic identification of hub genes Myd88 and Ccl3 and TWS-119 as a potential agent for the treatment of massive cerebral infarction

Background

Massive cerebral infarction (MCI) causes severe neurological deficits, coma and can even result in death. Here, we identified hub genes and pathways after MCI by analyzing microarray data from a murine model of ischemic stroke and identified potential therapeutic agents for the treatment of MCI.

Methods

Microarray expression profiling was performed using the GSE28731 and GSE32529 datasets from the Gene Expression Omnibus (GEO) database. Data from a sham group (n = 6 mice) and a middle cerebral artery occlusion (MCAO) group (n = 7 mice) were extracted to identify common differentially expressed genes (DEGs). After identifying gene interactions, we generated a protein-protein interaction (PPI) network with Cytoscape software. Then, the MCODE plug-in in Cytoscape was used to determine key sub-modules according to MCODE scores. Enrichment analyses were then conducted on DEGs in the key sub-modules to evaluate their biological functions. Furthermore, hub genes were identified by generating the intersections of several algorithms in the cytohubba plug-in; these genes were then verified in other datasets. Finally, we used Connectivity MAP (CMap) to identify potential agents for MCI therapy.

Results

A total of 215 common DEGs were identified and a PPI network was generated with 154 nodes and 947 edges. The most significant key sub-module had 24 nodes and 221 edges. Gene ontology (GO) analysis showed that the DEGs in this sub-module showed enrichment in inflammatory response, extracellular space and cytokine activity in terms of biological process, cellular component and molecular function, respectively. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that TNF signaling was the most enriched pathway. Myd88 and Ccl3 were identified as hub genes and TWS-119 was identified as the most potential therapeutic agent by CMap.

Conclusions

Bioinformatic analysis identified two hub genes (Myd88 and Ccl3) for ischemic injury. Further analysis identified TWS-119 as the best potential candidate for MCI therapy and that this target may be associated with TLR/MyD88 signaling.

ATP-induced hypothermia improves burn injury and relieves burn pain in mice

Thermal burn injury is a severe and life-threatening form of trauma that presents a significant challenge to clinical therapy. Therapeutic hypothermia has been shown to be beneficial in various human pathologies. Adenosine triphosphate (ATP) induces a hypothermic state that resembles hibernation-like suspended animation in mammals. This study investigates the potential protective role of ATP-induced hypothermia in thermal burn injury. Male C57BL/6 mice underwent a sham procedure or third-degree burn, and ATP-induced hypothermia was applied immediately or 1 h after burn injury. Our results show that ATP-induced hypothermia significantly improved burn depth progression and reduced collagen degradation. Moreover, hypothermia induced by ATP alleviated burn-induced hyperinflammatory responses and oxidative stress. Metabolomic profiling revealed that ATP-induced hypothermia reversed the shifts of metabolic profiles of the skin in burn mice. In addition, ATP-induced hypothermia relieved nociceptive and inflammatory pain, as observed in the antinociceptive test. Our findings suggest that ATP-induced hypothermia attenuates burn injury and provides new insights into first-aid therapy after thermal burn injury.

α-Tocopherol Protects Lipopolysaccharide-Activated BV2 Microglia

Microglia, the resident macrophage-like population in the central nervous system, play a crucial role in the pathogenesis of many neurodegenerative disorders by triggering an inflammatory response that leads to neuronal death. Neuroprotective compounds to treat or prevent neurodegenerative diseases are a new field of study in modern medicine. Microglia are activated in response to inflammatory stimuli. The pathogenesis of various neurodegenerative diseases is closely related to the constant activation of microglia due to their fundamental role as a mediator of inflammation in the brain environment. α-Tocopherol, also known as vitamin E, is reported to possess potent neuroprotective effects. The goal of this study was to investigate the biological effects of vitamin E on BV2 microglial cells, as a possible neuroprotective and anti-inflammatory agent, following stimulation with lipopolysaccharide (LPS). The results showed that the pre-incubation of microglia with α-tocopherol can guarantee neuroprotective effects during microglial activation induced by LPS. α-Tocopherol preserved the branched morphology typical of microglia in a physiological state. It also reduced the migratory capacity; the production of pro-inflammatory and anti-inflammatory cytokines such as TNF-α and IL-10; and the activation of receptors such as TRL4 and CD40, which modulate the PI3K-Akt signaling pathway. The results of this study require further insights and research, but they present new scenarios for the application of vitamin E as an antioxidant for the purpose of greater neuroprotection in vivo for the prevention of possible neurodegenerative diseases.

Protecting the injured central nervous system: Do anesthesia or hypothermia ameliorate secondary injury?

Traumatic injury to the central nervous system (CNS) and stroke initiate a cascade of processes that expand the area of tissue loss. The current review considers recent studies demonstrating that the induction of an anesthetic state or cooling the affected tissue (hypothermia) soon after injury can have a therapeutic effect. We first provide an overview of the neurobiological processes that fuel tissue loss after traumatic brain injury (TBI), spinal cord injury (SCI) and stroke. We then examine the rehabilitative effectiveness of therapeutic anesthesia across a variety of drug categories through a systematic review of papers in the PubMed database. We also review the therapeutic benefits hypothermia, another treatment that quells neural activity. We conclude by considering factors related to the safety, efficacy and timing of treatment, as well as the mechanisms of action. Clinical implications are also discussed.

Friends or foes: The mononuclear phagocyte system in ischemic stroke

Ischemic stroke (IS) is a major cause of disability and death in adults, and the immune response plays an indispensable role in its pathological process. After the onset of IS, an inflammatory storm, with the infiltration and mobilization of the mononuclear phagocyte system (MPS), is triggered in the brain. Microglia are rapidly activated in situ, followed by waves of circulating monocytes into the ischemic area. Activated microglia and monocytes/macrophages are mainly distributed in the peri-infarct area. These cells have similar morphology and functions, such as secreting cytokines and phagocytosis. Previously, the presence of the MPS was considered a marker of an exacerbated inflammatory response that contributes to brain damage. However, recent studies have suggested a rather complicated role of the MPS in IS. Here, we reviewed articles focusing on various functions of the MPS among different phases of IS, including recruitment, polarization, phagocytosis, angiogenesis, and interaction with other types of cells. Moreover, due to the characteristics of the MPS, we also noted clinical research addressing alterations in the MPS as potential biomarkers for IS patients for the purposes of predicting prognosis and developing novel therapeutic strategies.

Immunomodulatory Therapeutic Effects of Curcumin on M1/M2 Macrophage Polarization in Inflammatory Diseases

BACKGROUND

Due to their plasticity, macrophages exert critical effects on both promoting and suppressing inflammatory processes. Pathologic inflammatory conditions are frequently correlated with dynamic alterations in macrophage activation, with classically activated M1 cells associated with the promotion and maintenance of inflammation and M2 cells being linked to the resolution or smouldering of chronic inflammation. Inflammation deputes a common feature of various chronic diseases and the direct involvement in the insurgence and development of these conditions. Macrophages participate in an autoregulatory loop characterizing the inflammatory process, as they produce a wide range of biologically active mediators that exert either deleterious or beneficial effects during the inflammation. Therefore, balancing the favorable ratios of M1/M2 macrophages can help ameliorate the inflammatory landscape of pathologic conditions. Curcumin is a component of turmeric with many pharmacological properties.

OBJECTIVE

Recent results from both in-vivo and in-vitro studies have indicated that curcumin can affect polarization and/or functions of macrophage subsets in the context of inflammation-related diseases. There is no comprehensive review of the impact of curcumin on cytokines involved in macrophage polarization in the context of inflammatory diseases. The present review will cover some efforts to explore the underlying molecular mechanisms by which curcumin modulates the macrophage polarization in distant pathological inflammatory conditions, such as cancer, autoimmunity, renal inflammation, stroke, atherosclerosis, and macrophage-driven pathogenesis.

RESULTS

The accumulation of the findings from in vitro and in vivo experimental studies suggests that curcumin beneficially influences M1 and M2 macrophages in a variety of inflammatory diseases with unfavorable macrophage activation.

CONCLUSION

Curcumin not only enhances anti-tumor immunity (via shifting M polarization towards M1 phenotype and/or up-regulation of M1 markers expression) but ameliorates inflammatory diseases, including autoimmune diseases (experimental autoimmune myocarditis and Behcet's disease), nephropathy, chronic serum sickness, stroke, and atherosclerosis.

N6-methyladenosine RNA is modified in the rat hippocampus following traumatic brain injury with hypothermia treatment

Recent studies have suggested a role for N6-methyladenosine (m6A) modification in neurological diseases. Hypothermia, a commonly used treatment for traumatic brain injury, plays a neuroprotective role by altering m6A modifications. In this study, methylated RNA immunoprecipitation sequencing (MeRIP-Seq) was applied to conduct a genome-wide analysis of RNA m6A methylation in the rat hippocampus of Sham and traumatic brain injury (TBI) groups. In addition, we identified the expression of mRNA in the rat hippocampus after TBI with hypothermia treatment. Compared with the Sham group, the sequencing results of the TBI group showed that 951 different m6A peaks and 1226 differentially expressed mRNAs were found. We performed cross-linking analysis of the data of the two groups. The result showed that 92 hyper-methylated genes were upregulated, 13 hyper-methylated genes were downregulated, 25 hypo-methylated genes were upregulated, and 10 hypo-methylated genes were downregulated. Moreover, a total of 758 differential peaks were identified between TBI and hypothermia treatment groups. Among these differential peaks, 173 peaks were altered by TBI and reversed by hypothermia treatment, including Plat, Pdcd5, Rnd3, Sirt1, Plaur, Runx1, Ccr1, Marveld1, Lmnb2, and Chd7. We found that hypothermia treatment transformed some aspects of the TBI-induced m6A methylation landscape of the rat hippocampus.

Selective brain hypothermia attenuates focal cerebral ischemic injury and improves long-term neurological outcome in aged female mice

AIMS

This study aimed to investigate the effects of mild selective brain hypothermia on aged female ischemic mice.

METHODS

A distal middle cerebral artery occlusion (dMCAO) model was established in aged female mice, who were then subjected to mild selective brain hypothermia immediately after the dMCAO procedure. Neurological behavioral examinations were conducted prior to and up to 35 days post-ischemia. Infarct volume, brain atrophy, pro-inflammation, and anti-inflammation microglia/macrophages phenotype and white matter injury were evaluated by immunofluorescence staining. Correlations between neurological behaviors and histological parameters were evaluated by Pearson product linear regression analysis.

RESULTS

Sensorimotor and cognitive function tests confirmed the protective effect of mild selective brain hypothermia in elderly female ischemic mice. In addition, hypothermia decreased the infarct volume and brain atrophy induced by focal cerebral ischemia. Furthermore, hypothermia alleviated ischemia-induced short-term and long-term white matter injury, which was correlated with behavioral deficits. Finally, hypothermia suppressed the harmful immunological response by promoting the transformation of pro-inflammatory microglia/macrophages to anti-inflammatory phenotype. This polarization was negatively correlated with neuronal loss and white matter injury.

CONCLUSION

Mild selective brain hypothermia promoted long-term functional recovery by alleviating white matter damage in an aged female mouse model of ischemia.

The protective effects of nesfatin-1 in neurological dysfunction after spinal cord injury by inhibiting neuroinflammation

AIMS

Spinal cord injury (SCI) is one of the most severe neurological diseases. However, there is still no effective treatment for it. Nesfatin, a precursor neuropeptide derived from nucleobindin 2 (NUCB2), has displayed a wide range of protective effects in different types of cells and tissue. However, the effects of nesfatin-1 in SCI have not been reported before.

MATERIALS AND METHODS

A SCI model was established. The behavior of mice was assessed using the Basso, Beattie, and Bresnahan (BBB) assessment.

RESULTS

Here, we report that the administration of nesfatin-1 improved neurological recovery in SCI mice by increasing BBB scores, reducing lesion area volume and spinal cord water content. Also, nesfatin-1 ameliorated oxidative stress by reducing reactive oxygen species (ROS) levels and increasing superoxide dismutase (SOD) activity. We also found that nesfatin-1 prevented neuronal apoptosis in SCI mice by reducing caspase 3 activity and the expression of Bax, as well as increasing B-cell lymphoma-2 (Bcl-2). Additionally, nesfatin-1 reduced the levels of interleukin 6 (IL-6), interleukin-1β (IL-1β), and tumor necrosis factor-α (TNF-α). Nesfatin-1 also promoted microglia towards M2 polarization by increasing the marker CD206 but reducing CD16. Importantly, nesfatin-1 enhanced the phosphorylation of signal transducer and activator of transcription 1 (STAT1) but reduced the expression levels of toll-like receptor 4 (TLR4) and phosphorylated nuclear factor kappa-B p65 (p-NF-κB p65).

CONCLUSION

Our findings imply that nesfatin-1 exerts neuroprotective actions in SCI by promoting the activation of M2 microglia, and its underlying mechanisms might be related to the activation of STAT1 and inhibition of the TLR4/NF-κB signaling pathway.

Glycosaminoglycan scaffolding and neural progenitor cell transplantation promotes regenerative immunomodulation in the mouse ischemic brain

Ischemic stroke is a leading cause of morbidity and mortality, with limited treatments that can facilitate brain regeneration. Neural progenitor cells (NPCs) hold promise for replacing tissue lost to stroke, and biomaterial approaches may improve their efficacy to overcome hurdles in clinical translation. The immune response and its role in stroke pathogenesis and regeneration may interplay with critical mechanisms of stem cell and biomaterial therapies. Cellular therapy can modulate the immune response to reduce toxic neuroinflammation early after ischemia. However, few studies have attempted to harness the regenerative effects of neuroinflammation to augment recovery. Our previous studies demonstrated that intracerebrally transplanted NPCs encapsulated in a chondroitin sulfate-A hydrogel (CS-A + NPCs) can improve vascular regeneration after stroke. In this paper, we found that CS-A + NPCs affect the microglia/macrophage response to promote a regenerative phenotype following stroke in mice. Following transplantation, PPARγ-expressing microglia/macrophages, and MCP-1 and IL-10 protein levels are enhanced. Secreted immunomodulatory factor expression of other factors was altered compared to NPC transplantation alone. Post-stroke depression-like behavior was reduced following cellular and material transplantation. Furthermore, we showed in cultures that microglia/macrophages encapsulated in CS-A had increased expression of angiogenic and arteriogenic mediators. Neutralization with anti-IL-10 antibody negated these effects in vitro. Cumulatively, this work provides a framework for understanding the mechanisms by which immunomodulatory biomaterials can enhance the regenerative effects of cellular therapy for ischemic stroke and other brain injuries.

Browning of the white adipose tissue regulation: new insights into nutritional and metabolic relevance in health and diseases

Adipose tissues are dynamic tissues that play crucial physiological roles in maintaining health and homeostasis. Although white adipose tissue and brown adipose tissue are currently considered key endocrine organs, they differ functionally and morphologically. The existence of the beige or brite adipocytes, cells displaying intermediary characteristics between white and brown adipocytes, illustrates the plastic nature of the adipose tissue. These cells are generated through white adipose tissue browning, a process associated with augmented non-shivering thermogenesis and metabolic capacity. This process involves the upregulation of the uncoupling protein 1, a molecule that uncouples the respiratory chain from Adenosine triphosphate synthesis, producing heat. β-3 adrenergic receptor system is one important mediator of white adipose tissue browning, during cold exposure. Surprisingly, hyperthermia may also induce beige activation and white adipose tissue beiging. Physical exercising copes with increased levels of specific molecules, including Beta-Aminoisobutyric acid, irisin, and Fibroblast growth factor 21 (FGF21), which induce adipose tissue browning. FGF21 is a stress-responsive hormone that interacts with beta-klotho. The central roles played by hormones in the browning process highlight the relevance of the individual lifestyle, including circadian rhythm and diet. Circadian rhythm involves the sleep-wake cycle and is regulated by melatonin, a hormone associated with UCP1 level upregulation. In contrast to the pro-inflammatory and adipose tissue disrupting effects of the western diet, specific food items, including capsaicin and n-3 polyunsaturated fatty acids, and dietary interventions such as calorie restriction and intermittent fasting, favor white adipose tissue browning and metabolic efficiency. The intestinal microbiome has also been pictured as a key factor in regulating white tissue browning, as it modulates bile acid levels, important molecules for the thermogenic program activation. During embryogenesis, in which adipose tissue formation is affected by Bone morphogenetic proteins that regulate gene expression, the stimuli herein discussed influence an orchestra of gene expression regulators, including a plethora of transcription factors, and chromatin remodeling enzymes, and non-coding RNAs. Considering the detrimental effects of adipose tissue browning and the disparities between adipose tissue characteristics in mice and humans, further efforts will benefit a better understanding of adipose tissue plasticity biology and its applicability to managing the overwhelming burden of several chronic diseases.

Lomitapide ameliorates middle cerebral artery occlusion-induced cerebral ischemia/reperfusion injury by promoting neuronal autophagy and inhibiting microglial migration

AIMS

Stroke has a high incidence and is a disabling condition that can lead to severe cognitive, motor, and sensory dysfunction. In this study, we employed a drug repurposing strategy to investigate the neuroprotective effect of lomitapide on focal ischemic brain injury and explore its potential mechanism of action.

METHODS

Experimental cerebral ischemia was induced by middle cerebral artery occlusion (MCAO) in adult male C57BL/6 mice and simulated by oxygen-glucose deprivation in N2a-BV2 cells in co-cultivation.

RESULTS

Lomitapide significantly increased the survival rate, reduced the neuronal tissue loss, and improved the neurological function after MCAO. Furthermore, lomitapide could increase the expression of LC3-II, reduce the expression of P62 and LAMP2, promote autophagic flux, and inhibit apoptosis by increasing and inhibiting the expression of the apoptosis-associated proteins Bcl-2 and Bax, respectively. In addition, lomitapide inhibited the migration of pro-inflammatory microglia.

CONCLUSION

Lomitapide is a lipid-lowering drug, and this is the first study to explore its protective effect on ischemic nerve injury in vitro and in vivo. Our results suggest that lomitapide can be repositioned as a potential therapeutic drug for the treatment of stroke.

Consensus recommendations on therapeutic hypothermia after minimally invasive intracerebral hemorrhage evacuation from the hypothermia for intracerebral hemorrhage (HICH) working group

Background and purpose

Therapeutic hypothermia (TH), or targeted temperature management (TTM), is a classic treatment option for reducing inflammation and potentially other destructive processes across a wide range of pathologies, and has been successfully used in numerous disease states. The ability for TH to improve neurological outcomes seems promising for inflammatory injuries but has yet to demonstrate clinical benefit in the intracerebral hemorrhage (ICH) patient population. Minimally invasive ICH evacuation also presents a promising option for ICH treatment with strong preclinical data but has yet to demonstrate functional improvement in large randomized trials. The biochemical mechanisms of action of ICH evacuation and TH appear to be synergistic, and thus combining hematoma evacuation with cooling therapy could provide synergistic benefits. The purpose of this working group was to develop consensus recommendations on optimal clinical trial design and outcomes for the use of therapeutic hypothermia in ICH in conjunction with minimally invasive ICH evacuation.

Methods

An international panel of experts on the intersection of critical-care TH and ICH was convened to analyze available evidence and form a consensus on critical elements of a focal cooling protocol and clinical trial design. Three focused sessions and three full-group meetings were held virtually from December 2020 to February 2021. Each meeting focused on a specific subtopic, allowing for guided, open discussion.

Results

These recommendations detail key elements of a clinical cooling protocol and an outline for the roll-out of clinical trials to test and validate the use of TH in conjunction with hematoma evacuation as well as late-stage protocols to improve the cooling approach. The combined use of systemic normothermia and localized moderate (33.5°C) hypothermia was identified as the most promising treatment strategy.

Conclusions

These recommendations provide a general outline for the use of TH after minimally invasive ICH evacuation. More research is needed to further refine the use and combination of these promising treatment paradigms for this patient population.

Microglia-mediated neuroinflammation and neuroplasticity after stroke

Stroke remains a major cause of long-term disability and mortality worldwide. The immune system plays an important role in determining the condition of the brain following stroke. As the resident innate immune cells of the central nervous system, microglia are the primary responders in a defense network covering the entire brain parenchyma, and exert various functions depending on dynamic communications with neurons, astrocytes, and other neighboring cells under both physiological or pathological conditions. Microglia activation and polarization is crucial for brain damage and repair following ischemic stroke, and is considered a double-edged sword for neurological recovery. Microglia can exist in pro-inflammatory states and promote secondary brain damage, but they can also secrete anti-inflammatory cytokines and neurotrophic factors and facilitate recovery following stroke. In this review, we focus on the role and mechanisms of microglia-mediated neuroinflammation and neuroplasticity after ischemia and relevant potential microglia-based interventions for stroke therapy.

Hypothermia Protects against Ischemic Stroke through Peroxisome-Proliferator-Activated-Receptor Gamma

Ischemic stroke (IS) remains a global public health burden and requires novel strategies. Hypothermia plays a beneficial role in central nervous system diseases. However, the role of hypothermia in IS has not yet been elucidated. In this study, we determined the role of hypothermia in IS and explored its underlying mechanisms. The IS phenotype was detected based on infarct size, infarct volume, and brain edema in mice. Neuroinflammation was evaluated by the activation of microglial cells and the expression of inflammatory genes after ischemia/reperfusion (I/R) and oxygen-glucose deprivation/reperfusion (OGD/R). Neuronal cell apoptosis, cleaved caspase-3 and Bax/Bcl-2 expressions, cell viability, and lactate dehydrogenase (LDH) release were detected after I/R and OGD/R. Blood–brain barrier (BBB) permeability was calculated based on Evans blue extravasation, tight junction protein expression, cell viability, and LDH release after I/R and OGD/R. The expression of peroxisome proliferator-activated receptor gamma (PPARγ) was assessed after OGD/R. Our results suggested that hypothermia significantly reduced infarct size, brain edema, and neuroinflammation after I/R. Hypothermia increased PPARγ expression in microglial cells after OGD/R. Mechanistic studies revealed that hypothermia was a protectant against IS, including attenuated apoptosis of neuronal cells and BBB disruption after I/R and OGD/R, by upregulating PPARγ expression. The hypothermic effect was reversed by GW9662, a PPARγ inhibitor. Our data showed that hypothermia may reduce microglial cell-mediated neuroinflammation by upregulating PPARγ expression in microglial cells. Targeting hypothermia may be a feasible approach for IS treatment.

Non-mitogenic fibroblast growth factor 1 protects against ischemic stroke by regulating microglia/macrophage polarization through Nrf2 and NF-κB pathways

Microglia are immune cells in the central nervous system (CNS) that participate in response to pathological process after ischemic injury. Non-mitogenic fibroblast growth factor 1 (nmFGF1) is an effective neuroprotective factor that is also known as a metabolic regulator. The present study aimed to investigate the effects and mechanism of the neuroprotective ability of nmFGF1 on microglia in mice after photothrombosis (PT) stroke model, to determine whether it could ameliorate ischemic injury in stroke experiment. We discovered that the intranasal administration of nmFGF1 reduced infarct size and ameliorated neurological deficits in behavioral assessment by regulating the secretion of proinflammatory and anti-inflammatory cytokines. Furthermore, in the in vitro experiments, we found that nmFGF1 regulated the expression levels of proinflammatory and anti-inflammatory cytokines in oxygen-glucose deprivation (OGD) and lipopolysaccharide (LPS) stimulation. Evidence have shown that when nuclear factor erythroid 2-related factor 2 (Nfr2) is activated, it inhibits nuclear factor-kappa B (NF-κB) activation to alleviate inflammation. Interestingly, nmFGF1 treatment in vivo remarkably inhibited NF-κB pathway activation and activated Nrf2 pathway. In addition, nmFGF1 and NF-κB inhibitor (BAY11-7082) inhibited NF-κB pathway in LPS-stimulated BV2 microglia. Moreover, in LPS-stimulated BV2 microglia, the anti-inflammatory effect produced by nmFGF1 was knocked down by Nrf2 siRNA. These results indicate that nmFGF1 promoted functional recovery in experimental stroke by modulating microglia/macrophage-mediated neuroinflammation via Nrf2 and NF-κB signaling pathways, making nmFGF1 a potential agent against ischemic stroke.

The Role of CCL2/CCR2 Axis in Cerebral Ischemia-Reperfusion Injury and Treatment: From Animal Experiments to Clinical Trials

C-C motif chemokine ligand 2 (CCL2) is a member of the monocyte chemokine protein family, which binds to its receptor CCR2 to induce monocyte infiltration and mediate inflammation. The CCL2/CCR2 signaling pathway participates in the transduction of neuroinflammatory information between all types of cells in the central nervous system. Animal studies and clinical trials have shown that CCL2/CCR2 mediate the pathological process of ischemic stroke, and a higher CCL2 level in serum is associated with a higher risk of any form of stroke. In the acute phase of cerebral ischemia-reperfusion, the expression of CCL2/CCR2 is increased in the ischemic penumbra, which promotes neuroinflammation and enhances brain injury. In the later phase, it participates in the migration of neuroblasts to the ischemic area and promotes the recovery of neurological function. CCL2/CCR2 gene knockout or activity inhibition can reduce the nerve inflammation and brain injury induced by cerebral ischemia-reperfusion, suggesting that the development of drugs regulating the activity of the CCL2/CCR2 signaling pathway could be used to prevent and treat the cell injury in the acute phase and promote the recovery of neurological function in the chronic phase in ischemic stroke patients.

Post-ischemic protein restriction induces sustained neuroprotection, neurological recovery, brain remodeling, and gut microbiota rebalancing

BACKGROUND

Moderate dietary protein restriction confers neuroprotection when applied before ischemic stroke. How a moderately protein-reduced diet influences stroke recovery when administered after stroke, is a clinically relevant question. This question has not yet been investigated.

METHODS

Male C57BL6/J mice were exposed to transient intraluminal middle cerebral artery occlusion. Immediately after the stroke, mice were randomized to two normocaloric diets: a moderately protein-reduced diet containing 8% protein (PRD) or normal diet containing 20% protein (ND). Post-stroke neurological deficits were evaluated by a comprehensive test battery. Antioxidant and neuroinflammatory responses in the brain and liver were evaluated by Western blot and RTqPCR. Stroke-induced brain injury, microvascular integrity, glial responses, and neuroplasticity were assessed by immunohistochemistry. Fecal microbiota analysis was performed using 16S ribosomal RNA amplicon sequencing.

RESULTS

We show that PRD reduces brain infarct volume after three days and enhances neurological and, specifically, motor-coordination recovery over six weeks in stroke mice. The recovery-promoting effects of PRD were associated with increased antioxidant responses and reduced neuroinflammation. Histochemical studies revealed that PRD increased long-term neuronal survival, increased peri-infarct microvascular density, reduced microglia/macrophage accumulation, increased contralesional pyramidal tract plasticity, and reduced brain atrophy. Fecal microbiota analysis showed reduced bacterial richness and diversity in ischemic mice on ND starting at 7 dpi. PRD restored bacterial richness and diversity at these time points.

CONCLUSION

Moderate dietary protein restriction initiated post-ischemic stroke induces neurological recovery, brain remodeling, and neuroplasticity in mice by mechanisms involving antiinflammation and, in the post-acute phase, commensal gut microbiota rebalancing.

Post-stroke treatment with argon preserved neurons and attenuated microglia/macrophage activation long-termly in a rat model of transient middle cerebral artery occlusion (tMCAO)

In a previous study from our group, argon has shown to significantly attenuate brain injury, reduce brain inflammation and enhance M₂ microglia/macrophage polarization until 7 days after ischemic stroke. However, the long-term effects of argon have not been reported thus far. In the present study, we analyzed the underlying neuroprotective effects and potential mechanisms of argon, up to 30 days after ischemic stroke. Argon administration with a 3 h delay after stroke onset and 1 h after reperfusion demonstrated long-term neuroprotective effect by preserving the neurons at the ischemic boundary zone 30 days after stroke. Furthermore, the excessive microglia/macrophage activation in rat brain was reduced by argon treatment 30 days after ischemic insult. However, long-lasting neurological improvement was not detectable. More sensorimotor functional measures, age- and disease-related models, as well as further histological and molecular biological analyses will be needed to extend the understanding of argon’s neuroprotective effects and mechanism of action after ischemic stroke.

Calorie restriction or dietary restriction: how far they can protect the brain against neurodegenerative diseases?

Finding the correct nutritional intervention is one of the biggest challenges in treating patients with neurodegenerative diseases. In general, these patients develop strong metabolic alterations, resulting in lower treatment efficacy and higher mortality rates. However, there are still many open questions regarding the effectiveness of dietary interventions in neurodiseases. Some studies have shown that a reduction in calorie intake activates key pathways that might be important for preventing or slowing down the progression of such diseases. However, it is still unclear whether these neuroprotective effects are associated with an overall reduction in calories (hypocaloric diet) or a specific nutrient restriction (diet restriction). Therefore, here we discuss how commonly or differently hypocaloric and restricted diets modulate signaling pathways and how these changes can protect the brain against neurodegenerative diseases.

Protective Effect of Mild Hypothermia on Spinal Cord Ischemia-Induced Delayed Paralysis and Spinal Cord Injury

To explore the mechanism regarding the regulation of spinal cord ischemia (SCI) in rats by mild hypothermia. A SCI rat model was established through aorta occlusion, and in some cases, the rats were intervened with mild hypothermia, after which motor function, microglia activation, and M1/M2 polarization in rats were measured. Also, the expression of inflammatory cytokines (IL-1β, IL-6 and TNF-α) and neuronal apoptosis were examined. Lipopolysaccharide (LPS)-induced M1 microglia and IL-4-induced M2 microglia were intrathecally injected into rats to evaluate the effect of microglial polarization on SCI. In in vitro experiments, primary microglial cells were treated under hypothermic condition, in which M1/M2 polarization and microglia apoptosis, the levels of iNOS, CD86, CD206, Arg-1 and inflammatory cytokines were assessed. Western blot analysis detected the activation of the TLR4/NF-κB pathway to investigate the role of this pathway in M1/M2 polarization. SCI treatment impaired motor function, induced higher M1 microglia proportion, and increased the levels of pro-inflammatory cytokines in rats, and mild hypothermic treatment attenuated these trends. Moreover, injection of M1 microglia increased M1 microglia proportion and increased the levels of pro-inflammatory cytokines, while injection of M2 microglia induced the reverse results, i.e. decreased M1 microglia proportion and reduced pro-inflammatory cytokine levels. In LPS-induced microglial cells, mild hypothermia treatment increased M2 microglia proportion and decreased pro-inflammatory cytokine levels, relative to normothermia. Mild hypothermia inactivated the TLR4/NF-κB pathway in LPS-treated microglia. TLR4 overexpression reversed the function of mild hypothermia in LPS-stimulated microglia, and under normal condition, TLR4/NF-κB pathway suppressed microglial M2 polarization. Mild hypothermia inhibits TLR4/NF-κB pathway and promotes microglial M2 polarization, thus attenuating SCI-induced injury and inflammation.

Targeted temperature management in cardiac surgery: a systematic review and meta-analysis on postoperative cognitive outcomes

BACKGROUND

Postoperative cognitive decline occurs commonly after cardiac surgery. The available literature is inconclusive on the role of intraoperative causal or protective factors.

METHODS

We systematically reviewed studies evaluating delayed neurocognitive recovery (DNR), postoperative neurocognitive disorder (NCD), stroke, and the mortality rates among patients undergoing hypothermic or normothermic cardiopulmonary bypass (CPB). We further performed a subgroup analysis for age, surgery type (coronary artery bypass grafting [CABG], valve surgery, or combined), and the mean arterial blood pressure (MAP) during CPB, and conducted a proportion meta-analysis after calculation of single proportions and confidence intervals (CIs).

RESULTS

We included a total of 58 studies with 9609 patients in our analysis. Among these, 1906 of 4010 patients (47.5%) had DNR, and 2071 of 7160 (28.9%) had postoperative NCD. Ninety of 4625 patients (2.0%) had a stroke, and 174 of 7589 (2.3%) died. There was no statistically significant relationship between the considered variables and DNR, NCD, stroke, and mortality. In the subgroup analysis comparing hypothermic with normothermic CPB, we found higher NCD rates after combined surgery; for normothermic CPB cases only, the rates of DNR and NCD were lower after combined surgery compared with CABG surgery. A MAP >70 mm Hg compared with MAP=50-70 mm Hg during CPB was associated with a lower rate of DNR.

CONCLUSIONS

Temperature, MAP during cardiopulmonary bypass age, and surgery type were not associated with neurocognitive disorders, stroke, and mortality in cardiac surgery. Normothermic cardiopulmonary bypass, particularly when performed with MAP >70 mm Hg, may reduce the risk of postoperative neurocognitive decline after cardiac surgery.

PROSPERO REGISTRATION NUMBER

CRD42019140844.

Hypothermia modulates myeloid cell polarization in neonatal hypoxic-ischemic brain injury

Background

Neonatal encephalopathy due to hypoxia–ischemia (HI) is a leading cause of death and disability in term newborns. Therapeutic hypothermia (HT) is the only recommended therapy. However, 30% still suffer from neurological deficits. Inflammation is a major hallmark of HI pathophysiology with myeloid cells being key players, participating either in progression or in resolution of injury-induced inflammation. In the present study, we investigated the impact of HT on the temporal and spatial dynamics of microglia/macrophage polarization after neonatal HI in newborn mice.

Methods

Nine-day-old C57BL/6 mice were exposed to HI through occlusion of the right common carotid artery followed by 1 h hypoxia. Immediately after HI, animals were cooled for 4 h or kept at physiological body core temperature. Analyses were performed at 1, 3 and 7 days post HI. Brain injury, neuronal cell loss, apoptosis and microglia activation were assessed by immunohistochemistry. A broad set of typical genes associated with classical (M1) and alternative (M2) myeloid cell activation was analyzed by real time PCR in ex vivo isolated CD11b⁺ microglia/macrophages. Purity and composition of isolated cells was determined by flow cytometry.

Results

Immediate HT significantly reduced HI-induced brain injury and neuronal loss 7 days post HI, whereas only mild non-significant protection from HI-induced apoptosis and neuronal loss were observed 1 and 3 days after HI. Microglia activation, i.e., Iba-1 immunoreactivity peaked 3 days after HI and was not modulated by HT. However, ex vivo isolated CD11b⁺ cells revealed a strong upregulation of the majority of M1 but also M2 marker genes at day 1, which was significantly reduced by HT and rapidly declined at day 3. HI induced a significant increase in the frequency of peripheral macrophages in sorted CD11b⁺ cells at day 1, which deteriorated until day 7 and was significantly decreased by HT.

Conclusion

Our data demonstrate that HT-induced neuroprotection is preceded by acute suppression of HI-induced upregulation of inflammatory genes in myeloid cells and decreased infiltration of peripheral macrophages, both representing potential important effector mechanisms of HT.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02314-9.

Hypoxia Tolerant Species: The Wisdom of Nature Translated into Targets for Stroke Therapy

Human neurons rapidly die after ischemia and current therapies for stroke management are limited to restoration of blood flow to prevent further brain damage. Thrombolytics and mechanical thrombectomy are the available reperfusion treatments, but most of the patients remain untreated. Neuroprotective therapies focused on treating the pathogenic cascade of the disease have widely failed. However, many animal species demonstrate that neurons can survive the lack of oxygen for extended periods of time. Here, we reviewed the physiological and molecular pathways inherent to tolerant species that have been described to contribute to hypoxia tolerance. Among them, Foxo3 and Eif5A were reported to mediate anoxic survival in Drosophila and Caenorhabditis elegans, respectively, and those results were confirmed in experimental models of stroke. In humans however, the multiple mechanisms involved in brain cell death after a stroke causes translation difficulties to arise making necessary a timely and coordinated control of the pathological changes. We propose here that, if we were able to plagiarize such natural hypoxia tolerance through drugs combined in a pharmacological cocktail it would open new therapeutic opportunities for stroke and likely, for other hypoxic conditions.

Methanol extract of Ficus platyphylla decreases cerebral ischemia induced injury in mice

ETHNOPHARMACOLOGICAL RELEVANCE

Extracts of the stem bark of Ficus paltyphylla (FP) are used in the Nigerian traditional medicine to manage psychoses, depression, epilepsy, pain, and inflammation. Our previous studies revealed that the methanol extract of FP ameliorate body core temperature.

AIM OF THE STUDY

A number of pharmacological agents that utilize mechanisms that enhanced neuronal survival and/or neural regeneration have been developed for the treatment of stroke. Hypothermia protects the brain from damage caused by ischemia by attenuating destructive processes such as neuroinflammation, excitotoxicity, blood-brain barrier disruption, apoptosis, and free radical formation following cerebral ischemia. In the present study, we examined the neuroprotective potential of FP on permanent occlusion of the middle cerebral artery (MCAO)-induced ischemia in mice.

MATERIAL AND METHODS

C57Bl mice were subjected to MCAO. FP was administered 1 h prior to and immediately after surgery. The brains were collected 24 h later and infarct volumes were measured using immune-histochemical staining, DAPI, NeuN, synaptophysin, and NR2B were quantified.

RESULTS

Administration of FP prior to MCAO significantly reduced infarct volume, with no effect on infarct volume immediately after MCAO. Higher numbers of cells and neurons were observed in the peri-infarct area in both groups of mice. FP-induced hypothermia protected tissue in the peri-infarct region from synaptophysin reduction. NMDA receptor 2 (NR2B) immunoreactivity is enhanced by MCAO, with no difference observed in both sham-operated and FP-induced hypothermia groups of mice.

CONCLUSIONS

The data suggest that FP might be useful in the reduction of ischemia-induced infarct volume when administered prior to the initiation of ischemia with no effect observed after ischemia induction.

MiR-499a prevents astrocytes mediated inflammation in ischemic stroke by targeting PTEN

INTRODUCTION

Ischemic stroke (IS) is a common and severe neurological disorder and is associated with high rates of mortality and morbidity. Inflammatory reaction in astrocytes is one of the important pathological factors of stroke. Improved understanding of the underlying molecular mechanisms should aid better treatment of the disease. This study aimed to test our hypothesis that a miR-499a played an important role in the inflammatory response in astrocytes induced by IS targeting phosphatase and tensin homologue deleted on chromosome 10 (PTEN).

METHODS

This study was comprised of two models: oxygen-glucose deprivation (OGD) and reoxygenation model. Quantitative real-time PCR (qRT-PCR) and Western blot were used to examine gene expression levels, and MTT assay analysis were used to examine cell states. The relationships between miR-499a and PTEN were confirmed by luciferase reporter assay.

RESULTS

MiR-499a was robustly downregulated with OGD induced injury in astrocytes. Forced transient expression of miR-499a in OGD astrocytes nearly completely reversed the inflammatory response. Knockdown of miR-499a by its specific inhibitor in healthy astrocytes induced the inflammatory response resembling those produced by OGD. On the other hand, PTEN was markedly upregulated in OGD astrocytes, which was reciprocal to the expression of miR-499a. PTEN was experimentally validated as a direct target gene for miR-499a. Overexpression of PTEN was able to induce an inflammatory response of astrocytes. Moreover, PTEN siRNA counteracted the inflammatory response induced by OGD.

CONCLUSIONS

Taken together, our findings indicate miR-499a as an important factor to prevent inflammatory response and suggest miR-499a as a new molecule for the treatment of IS. The present study also demonstrated the relationship between miR-499a and PTEN, with PTEN as a downstream signaling mediator of miR-499a in the inflammatory response of astrocytes induced by IS.

VSIG4 alleviates intracerebral hemorrhage induced brain injury by suppressing TLR4-regulated inflammatory response

AIMS

Numerous evidence demonstrated that macrophage mediated inflammation contributed to brain injury following ICH, but the molecular mechanism had not been well studied. V-set immunoglobulin-domain-containing 4 (VSIG4), specifically expresses in resting tissue-resident macrophages, can deliver anti-inflammatory signals into various inflammatory diseases. However, the role of VSIG4 on ICH has not been reported.

METHODS

In the present study, we investigated the levels of VSIG4 in macrophages following ICH. Furthermore, Macrophage M1/M2 polarization, pro-inflammatory cytokine production, BBB disruption, brain water content and neurological function were examined in ICH mice. In addition, TLR4/NF-κβ downstream signals were also analyzed.

RESULTS

The results showed that VSIG4 levels of macrophage decreased following ICH, leading to macrophage M1 polarization. Up-regulation of VSIG4 inhibited macrophage M1 polarization, pro-inflammatory cytokine production, BBB disruption, as well as neurological deficits. Up-regulation of VSIG4 attenuated macrophage TLR4 levels following ICH. Co-IP demonstrated that VSIG4 could interact with TLR4 and inhibit its expression.

CONCLUSIONS

Our data demonstrated that VSIG4 was negatively correlated with TLR4 and involved in the pathogenesis of ICH, which prevented brain injury and attenuated deleterious inflammatory responses following ICH. In addition, the anti-inflammatory effect of VSIG4 was mainly through the blockage of TLR4/NF-κβ signaling.

Cross-Talk of Atherosclerosis and Ischemic Stroke: Dramatic Role of Neutrophils

Context: Current investigations illustrate the increasing prevalence of atherosclerosis (AS) through the aggravating role of inappropriate lifestyle patterns. Atherosclerosis is the cause of important vascular-related diseases such as ischemic stroke (IS). Understanding AS pathophysiology can help reduce the incidence of AS-mediated diseases like ischemic stroke. Evidence Acquisition: For this narrative review article, we used the five mega databases of PubMed, Google Scholar, Scopus, Springer, and Science Direct. We searched from 2010 Jan to 2020 Dec and based on keywords and inclusion criteria, 77 articles were enrolled. Results: Based on prior articles on atherosclerosis and ischemic stroke pathophysiology, local and systemic inflammation is a vigorous factor in both diseasesIndeed, the fundamental inflammatory pathway involved atherosclerosis, and ischemic stroke is associated with the toll-like receptor 4/myeloid differentiation primary response 88/nuclear factor-kappa B (TLR4/ Myd88/ NF-κB) cascade. The functional paw of these intricate mechanisms are pro-inflammatory mediators, such as interleukin-1 beta (IL-1β), tumor necrosis factor (TNF-α), and interleukin-18 (IL-18) incite inflammation. Besides, the essential structures termed inflammasomes (multi proteins components), and multiplicity of immune and non-immune cells (i.e., neutrophils, monocytes, platelets, and macrophages) are beneficial in the induction of inflammatory microenvironment. Conclusions: Neutrophils could be the most effective cells in the inflammation-based mechanism in IS and AS. It is clarified that neutrophils with the recruitment of own vesicles and granules can afford to amplify inflammatory conditions and be a key cell in AS and IS cross-talk. Therefore, utilizing methods to control neutrophils-mediated mechanisms could be an effective method for the prevention of AS and IS.

Transient Global Ischemia-Induced Brain Inflammatory Cascades Attenuated by Targeted Temperature Management

Sudden cardiac arrest leads to a significantly increased risk of severe neurological impairment and higher mortality rates in survivors due to global brain tissue injury caused by prolonged whole-body ischemia and reperfusion. The brain undergoes various deleterious cascading events. Among these damaging mechanisms, neuroinflammation plays an especially crucial role in the exacerbation of brain damage. Clinical guidelines indicate that 33 °C and 36 °C are both beneficial for targeted temperature management (TTM) after cardiac arrest. To clarify the mechanistic relationship between TTM and inflammation in transient global ischemia (TGI) and determine whether 36 °C produces a neuroprotective effect comparable to 33 °C, we performed an experiment using a rat model. We found that TTM at 36 °C and at 33 °C attenuated neuronal cell death and apoptosis, with significant improvements in behavioral function that lasted for up to 72 h. TTM at 33 °C and 36 °C suppressed the propagation of inflammation including the release of high mobility group box 1 from damaged cells, the activation and polarization of the microglia, and the excessive release of activated microglia-induced inflammatory cytokines. There were equal neuroprotective effects for TTM at 36 °C and 33 °C. In addition, hypothermic complications and should be considered safe and effective after cardiac arrest.

Targeted Temperature Management at 36 °C Shows Therapeutic Effectiveness via Alteration of Microglial Activation and Polarization After Ischemic Stroke

Ischemic injury leads to cell death and inflammatory responses after stroke. Microglia especially play a crucial role in this brain inflammation. Targeted temperature management (TTM) at 33 °C has shown neuroprotective effects against many acute ischemic injuries. However, it has also shown some adverse effects in preclinical studies. Therefore, we explored the neuroprotective effect of TTM at 36 °C in the ischemic brain. To confirm the neuroprotective effects of hypothermia, mice were subjected to a permanent stroke and then treated with one of the TTM paradigms at 33 and 36 °C. For comparison of TTM at 33 and 36 °C, we examined neuronal cell death and inflammatory response, including activation and polarization of microglia in the ischemic brain. TTM at 33 and 36 °C showed neuroprotective effects in comparison with normal body temperature (NT) at 37.5 °C. Mice under TTM at 33 and 36 °C showed ~ 45-50% fewer TUNEL-positive cells than those under NT. In IVIS spectrum CT, the activation of microglia/macrophage in CX3CR1^GFP mice reduced after TTM at 33 and 36 °C in comparison with that after NT on day 7 after ischemic stroke. The number of Tmem119-positive cells under TTM at 33 and 36 °C was ~ 45-50% lower than that in mice under NT. TTM at 33 and 36 °C also increased the ratio of CD206-/CD86-positive cells than the ratio of CD86-/CD206-positive cells by ~ 1.2-fold. Thus, TTM at 33 and 36 °C could equivalently decrease the expression of certain cytokines after ischemic stroke. Our study suggested that TTM at 33 or 36 °C produces equivalent neuroprotective effects by attenuating cell death and by altering microglial activation and polarization. Therefore, TTM at 36 °C can be considered for its safety and effectiveness in ischemic stroke.

Salvianolic Acids for Injection alleviates cerebral ischemia/reperfusion injury by switching M1/M2 phenotypes and inhibiting NLRP3 inflammasome/pyroptosis axis in microglia in vivo and in vitro

ETHNOPHARMACOLOGICAL RELEVANCE

After cerebral ischemia/reperfusion injury, pro-inflammatory M1 and anti-inflammatory M2 phenotypes of microglia are involved in neuroinflammation, in which activation of NLRP3 inflammasome and subsequent pyroptosis play essential roles. Salvianolic Acids for Injection (SAFI) is Chinese medicine injection which composed of multiple phenolic acids extracted from Radix Salviae Miltiorrhizae, and has been reported to generate neuroprotective effects after cerebral ischemic insult in clinical and animal studies.

AIM OF THE STUDY

The present study was designed to investigate whether SAFI exerts neuroprotective effects by switching microglial phenotype and inhibiting NLRP3 inflammasome/pyroptosis axis in microglia.

MATERIALS AND METHODS

The middle cerebral artery occlusion/reperfusion (MCAO/R) model in rats and oxygen-glucose deprivation/reoxygenation (OGD/R) model in co-cultured primary neurons and primary microglia were utilized. The neuroprotective effect of SAFI was evaluated through measuring neurological deficit scores, neuropathological changes, inflammatory factors, cell phenotype markers, and related proteins of NLRP3 inflammasome/pyroptosis axis.

RESULTS

The results showed that SAFI treatment was able to: (1) produce a significant increase in neurological deficit scores and decrease in infarct volumes, and alleviate histological injury and neuronal apoptosis in cerebral cortex in MCAO/R model; (2) increase neuronal viability and reduce neuronal apoptosis in the OGD model; (3) reshape microglial polarization patterns from M1-like phenotype to M2-like phenotype; (4) inhibit the activation of the NLRP3 inflammasome and the expression of proteins related to NLRP3 inflammasome/pyroptosis axis in vivo and in vitro.

CONCLUSION

These findings indicate that SAFI exert neuroprotective effect, probably via reducing neuronal apoptosis, switching microglial phenotype from M1 towards M2, and inhibiting NLRP3 inflammasome/pyroptosis axis in microglia.

Sinomenine activation of Nrf2 signaling prevents inflammation and cerebral injury in a mouse model of ischemic stroke

Sinomenine (SINO), which is used clinically to treat rheumatoid arthritis and neuralgia, is derived from the root and stems of Sinomenium acutum. SINO has been reported to exert analgesic, sedative and anti-inflammatory effects, and provides a protective role against shock and organ damage. Studies have suggested that SINO primarily exerts it anti-inflammatory function by inhibiting NF-κB signaling. There is also evidence to indicate that SINO may regulate inflammation Nuclear factor (erythroid-derived 2)-like 2 (Nrf2) signaling. The present study aimed to investigate whether the anti-inflammatory and cerebral protective effects of SINO were induced through Nrf2 both in vitro and in vivo. The results revealed that SINO significantly upregulated Nrf2 protein expression levels, increased Nrf2 nuclear translocation and the upregulated the protein expression levels of downstream factors. The treatment of a middle cerebral artery occlusion model mice with SINO effectively reduced cerebral damage and inflammation, and restored the balance in cerebral oxidative stress. In addition, SINO treatment also promoted Nrf2-dependent microglia M1/M2 polarization and inhibited the phosphorylation of IκBα as well as NF-κB nuclear translocation. This revealed an important upstream event that contributed to its anti-inflammatory and cerebral tissue protective effects. In conclusion, the findings of the present study identified a novel pathway through which SINO may exert its anti-inflammatory and cerebral protective functions, and provided a molecular basis for the potential applications of SINO in the treatment of cerebral inflammatory disorders.

Danhong Injection Attenuates Cerebral Ischemia-Reperfusion Injury in Rats Through the Suppression of the Neuroinflammation

Neuroinflammation is one of the major causes of damage of the central nervous system (CNS) and plays a vital role in the pathogenesis of cerebral ischemia, which can result in long-term disability and neuronal death. Danhong injection (DHI), a traditional Chinese medicine injection, has been applied to the clinical treatment of cerebral stoke for many years. In this study, we investigated the protective effects of DHI on cerebral ischemia-reperfusion injury (CIRI) in rats and explored its potential anti-neuroinflammatory properties. CIRI in adult male SD rats was induced by middle cerebral artery occlusion (MCAO) for 1 h and reperfusion for 24 h. Results showed that DHI (0.5, 1, and 2 ml/kg) dose-dependently improved the neurological deficits and alleviated cerebral infarct volume and histopathological damage of the cerebral cortex caused by CIRI. Moreover, DHI (0.5, 1, and 2 ml/kg) inhibited the mRNA expressions of tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), intercellular cell adhesion molecule-1 (ICAM-1), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) in ischemic brains, downregulated TNF-α, IL-1β, and monocyte chemotactic protein-1 (MCP-1) levels in serum, and reduced the neutrophil infiltration (myeloperoxidase, MPO) in ischemic brains, in a dose-dependent manner. Immunohistochemical staining results also revealed that DHI dose-dependently diminished the protein expressions of ICAM-1 and COX-2, and suppressed the activation of microglia (ionized calcium-binding adapter molecule 1, Iba-1) and astrocyte (glial fibrillary acidic protein, GFAP) in the cerebral cortex. Western blot analysis showed that DHI significantly downregulated the phosphorylation levels of the proteins in nuclear factor κB (NF-κB) and mitogen-activated protein kinas (MAPK) signaling pathways in ischemic brains. These results indicate that DHI exerts anti-neuroinflammatory effects against CIRI, which contribute to the amelioration of CNS damage.

Hypothermia Protects Mice Against Ischemic Stroke by Modulating Macrophage Polarization Through Upregulation of Interferon Regulatory Factor-4

Background

Therapeutic hypothermia (TH) has been proven to be protective in ischemic stroke (IS) due to its anti-inflammatory capacity. Recently, the interferon regulatory factor 4 (IRF4) has been characterized as a central regulator of neuroinflammation in IS. Here we aim to determine whether IFR4 contributes to the neuroprotective effects of TH in IS.

Methods

In the present study, IRF4 knockout (IRF4^−/-) and wild-type (IRF4^+/+) mice were treated with or without TH after IS. Cerebral IRF4 expression, the production of pro-inflammatory and anti-inflammatory cytokines and macrophage polarization were determined at 8 hours after reperfusion. In addition, cerebral infarct volume and neurological function were evaluated at 7 days after IS.

Results

TH attenuates IS together with enhanced IRF4 expression as well as reduced production of pro-inflammatory cytokines. In addition, TH increased M2 macrophage polarization while inhibited M1 macrophage polarization. However, IRF4 knockout worsens neurological outcomes of stoke mice. The expression of pro-inflammatory cytokines were markedly increased in IRF4^−/- mice as compared with IRF4^+/+ mice at 8 h after stroke. Moreover, IRF4 knockout driven the macrophage polarization toward M1phenotype at 8 h after stroke. Most importantly, IRF4 knockout abolished the neuroprotective and anti-inflammatory effects of TH in IS.

Conclusion

Together, we report for the first time that TH attenuates neuroinflammation following IS by modulating M1/M2 macrophage polarization through the upregulation of IRF4 expression.

Temperature Plays an Essential Regulatory Role in the Tumor Immune Microenvironment

In recent years, emerging immunotherapy has been included in various malignant tumor treatment standards. Temperature has been considered to affect different pathophysiological reactions such as inflammation and cancer for a long time. However, in tumor immunology research, temperature is still rarely considered a significant variable. In this review, we discuss the effects of room temperature, body temperature, and the local tumor temperature on the tumor immune microenvironment from multiple levels and perspectives, and we discuss changes in the body's local and whole-body temperature under tumor conditions. We analyze the current use of ablation treatment-the reason for the opposite immune effect. We should pay more attention to the therapeutic potential of temperature and create a better antitumor microenvironment that can be combined with immunotherapy.

Glial Cell-Based Vascular Mechanisms and Transplantation Therapies in Brain Vessel and Neurodegenerative Diseases

Neurodevelopmental and neurodegenerative diseases (NDDs) with severe neurological/psychiatric symptoms, such as cerebrovascular pathology in AD, CAA, and chronic stroke, have brought greater attention with their incidence and prevalence having markedly increased over the past few years. Causes of the significant neuropathologies, especially those observed in neurological diseases in the CNS, are commonly believed to involve multiple factors such as an age, a total environment, genetics, and an immunity contributing to their progression, neuronal, and vascular injuries. We primarily focused on the studies of glial involvement/dysfunction in part with the blood-brain barrier (BBB) and the neurovascular unit (NVU) changes, and the vascular mechanisms, which have been both suggested as critical roles in chronic stroke and many other NDDs. It has been noted that glial cells including astrocytes (which outnumber other cell types in the CNS) essentially contribute more to the BBB integrity, extracellular homeostasis, neurotransmitter release, regulation of neurogenic niches in response to neuroinflammatory stimulus, and synaptic plasticity. In a recent study for NDDs utilizing cellular and molecular biology and genetic and pharmacological tools, the role of reactive astrocytes (RACs) and gliosis was demonstrated, able to trigger pathophysiological/psychopathological detrimental changes during the disease progression. We speculate, in particular, the BBB, the NVU, and changes of the astrocytes (potentially different populations from the RACs) not only interfere with neuronal development and synaptogenesis, but also generate oxidative damages, contribute to beta-amyloid clearances and disrupted vasculature, as well as lead to neuroinflammatory disorders. During the past several decades, stem cell therapy has been investigated with a research focus to target related neuro-/vascular pathologies (cell replacement and repair) and neurological/psychiatric symptoms (paracrine protection and homeostasis). Evidence shows that transplantation of neurogenic or vasculogenic cells could be achieved to pursue differentiation and maturation within the diseased brains as expected. It would be hoped that, via regulating functions of astrocytes, astrocytic involvement, and modulation of the BBB, the NVU and astrocytes should be among major targets for therapeutics against NDDs pathogenesis by drug and cell-based therapies. The non-invasive strategies in combination with stem cell transplantation such as the well-tested intranasal deliveries for drug and stem cells by our and many other groups show great translational potentials in NDDs. Neuroimaging and clinically relevant analyzing tools need to be evaluated in various NDDs brains.