Epothilone B Benefits Nigrostriatal Pathway Recovery by Promoting Microtubule Stabilization After Intracerebral Hemorrhage

Hypothermia protects the integrity of corticospinal tracts and alleviates mitochondria injury after intracerebral hemorrhage in mice

Disruption of corticospinal tracts (CST) is a leading factor for motor impairments following intracerebral hemorrhage (ICH) in the striatum. Previous studies have shown that therapeutic hypothermia (HT) improves outcomes of ICH patients. However, whether HT has a direct protection effect on the CST integrity and the underlying mechanisms remain largely unknown. In this study, we employed a chemogenetics approach to selectively activate bilateral warm-sensitive neurons in the preoptic areas to induce a hypothermia-like state. We then assessed effects of HT treatment on the integrity of CST and motor functional recovery after ICH. Our results showed that HT treatment significantly alleviated axonal degeneration around the hematoma and the CST axons at remote midbrain region, ultimately promoted skilled motor function recovery. Anterograde and retrograde tracing revealed that HT treatment protected the integrity of the CST over an extended period. Mechanistically, HT treatment prevented mitochondrial swelling in degenerated axons around the hematoma, alleviated mitochondrial impairment by reducing mitochondrial ROS accumulation and improving mitochondrial membrane potential in primarily cultured cortical neurons with oxyhemoglobin treatment. Serving as a proof of principle, our study provided novel insights into the application of HT to improve functional recovery after ICH.

Epothilone B loaded in acellular nerve allograft enhanced sciatic nerve regeneration in rats

BACKGROUND

Epothilone B (EpoB) is a microtubule-stabilizing agent with neuroprotective properties.

OBJECTIVES

This study examines the regenerative properties of ANA supplemented with EpoB on a sciatic nerve deficit in male Wistar rats.

METHODS

For this purpose, the 10 mm nerve gap was filled with acellular nerve allografts (ANAs) containing EpoB at 0.1, 1, and 10 nM concentrations. The sensorimotor recovery was evaluated up to 16 weeks after the operation. Real-time PCR, histomorphometry analysis, and electrophysiological evaluation were also used to evaluate the process of nerve regeneration.

RESULTS

ANA/EpoB (0.1 nM) significantly improved sensorimotor recovery in rats compared to ANA, ANA/EpoB (1 nM), and ANA/EpoB (10 nM) groups. This led to reduced muscle atrophy, improved sciatic functional index, and thermal paw withdrawal reflex latency, indicating nerve regeneration and target organ reinnervation. The electrophysiological and histomorphometry findings also confirmed the ANA/EpoB regenerative properties (0.1 nM). EpoB only enhanced ANA regenerative properties at 0.1 nM, with no therapeutic effects at higher concentrations.

CONCLUSION

Totally, we concluded that ANA loaded with 0.1 nM EpoB can effectively reconstruct the transected sciatic nerve in rats, likely by enhancing axonal sprouting and extension.

Contralesional Anodal Transcranial Direct Current Stimulation Promotes Intact Corticospinal Tract Axonal Sprouting and Functional Recovery After Traumatic Brain Injury in Mice

BACKGROUND

Anodal transcranial direct current stimulation (AtDCS), a neuromodulatory technique, has been applied to treat traumatic brain injury (TBI) in patients and was reported to promote functional improvement. We evaluated the effect of contralesional AtDCS on axonal sprouting of the intact corticospinal tract (CST) and the underlying mechanism in a TBI mouse model to provide more preclinical evidence for the use of AtDCS to treat TBI.

METHODS

TBI was induced in mice by a contusion device. Then, the mice were subjected to contralesional AtDCS 5 days per week followed by a 2-day interval for 7 weeks. After AtDCS, motor function was evaluated by the irregular ladder walking, narrow beam walking, and open field tests. CST sprouting was assessed by anterograde and retrograde labeling of corticospinal neurons (CSNs), and the effect of AtDCS was further validated by pharmacogenetic inhibition of axonal sprouting using clozapine-N-oxide (CNO).

RESULTS

TBI resulted in damage to the ipsilesional cortex, while the contralesional CST remained intact. AtDCS improved the skilled motor functions of the impaired hindlimb in TBI mice by promoting CST axon sprouting, specifically from the intact hemicord to the denervated hemicord. Furthermore, electrical stimulation of CSNs significantly increased the excitability of neurons and thus activated the mechanistic target of rapamycin (mTOR) pathway.

CONCLUSIONS

Contralesional AtDCS improved skilled motor following TBI, partly by promoting axonal sprouting through increased neuronal activity and thus activation of the mTOR pathway.

Selective HDAC6 inhibition protects against blood-brain barrier dysfunction after intracerebral hemorrhage

BACKGROUNDS

Blood-brain barrier (BBB) disruption after intracerebral hemorrhage (ICH) significantly induces neurological impairment. Previous studies showed that HDAC6 knockdown or TubA can protect the TNF-induced endothelial dysfunction. However, the role of HDAC6 inhibition on ICH-induced BBB disruption remains unknown.

METHODS

Hemin-induced human brain microvascular endothelial cells (HBMECs) and collagenase-induced rats were employed to investigated the underlying impact of the HDAC6 inhibition in BBB lesion and neuronal dysfunction after ICH.

RESULTS

We found a significant decrease in acetylated α-tubulin during early phase of ICH. Both 25 or 40 mg/kg of TubA could relieve neurological deficits, perihematomal cell apoptosis, and ipsilateral brain edema in ICH animal model. TubA or specific siRNA of HDAC6 inhibited apoptosis and reduced the endothelial permeability of HBMECs. HDAC6 inhibition rescued the degradation of TJ proteins and repaired TJs collapses after ICH induction. Finally, the results suggested that the protective effects on BBB after ICH induction were exerted via upregulating the acetylated α-tubulin and reducing stress fiber formation.

CONCLUSIONS

Inhibition of HDAC6 expression showed beneficial effects against BBB disruption after experimental ICH, which suggested that HDAC6 could be a novel and promising target for ICH treatment.

Chemogenetic stimulation of intact corticospinal tract during rehabilitative training promotes circuit rewiring and functional recovery after stroke

BACKGROUND

Neuromodulatory techniques have been proven to enhance functional recovery after stroke in patients and animals, such as repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS). However, the success and feasibility of these approaches were often variable, largely due to a lack of target specificity.

OBJECTIVE

We explored the effects of specific chemogenetic stimulation of intact corticospinal tract during rehabilitative training on functional recovery after stroke in mice.

METHODS

We developed a viral-based intersectional targeting approach that allows specific chemogentic activation of contralateral hindlimb corticospinal neurons (CSNs) in a photothrombotic stroke model.

RESULTS

We demonstrated that specific chemogenetic activation of CSNs, when combined with daily rehabilitation training, leads to significant skilled motor functional recovery via promoting corticospinal tract (CST) axons midline crossing sprouting from intact to the denervated spinal hemicord, and rewiring new functional circuits by new synapse formation. Mechanistically, we revealed that combined chemogenetic stimulation of CSNs and daily rehabilitation training significantly enhanced the mTOR activity of CSNs.

CONCLUSIONS

Our findings highlight the great potential of specific neural activation protocols in combination with motor training for the recovery of skilled motor functions after stroke.

Acetylated α-tubulin alleviates injury to the dendritic spines after ischemic stroke in mice

BACKGROUND AND AIM

Functional recovery is associated with the preservation of dendritic spines in the penumbra area after stroke. Previous studies found that polymerized microtubules (MTs) serve a crucial role in regulating dendritic spine formation and plasticity. However, the mechanisms that are involved are poorly understood. This study is designed to understand whether the upregulation of acetylated α-tubulin (α-Ac-Tub, a marker for stable, and polymerized MTs) could alleviate injury to the dendritic spines in the penumbra area and motor dysfunction after ischemic stroke.

METHODS

Ischemic stroke was mimicked both in an in vivo and in vitro setup using middle cerebral artery occlusion and oxygen-glucose deprivation models. Thy1-YFP mice were utilized to observe the morphology of the dendritic spines in the penumbra area. MEC17 is the specific acetyltransferase of α-tubulin. Thy1 Cre^ERT2-eYFP and MEC17^fl/fl mice were mated to produce mice with decreased expression of α-Ac-Tub in dendritic spines of pyramidal neurons in the cerebral cortex. Moreover, AAV-PHP.B-DIO-MEC17 virus and tubastatin A (TBA) were injected into Thy1 Cre^ERT2-eYFP and Thy1-YFP mice to increase α-Ac-Tub expression. Single-pellet retrieval, irregular ladder walking, rotarod, and cylinder tests were performed to test the motor function after the ischemic stroke.

RESULTS

α-Ac-Tub was colocalized with postsynaptic density 95. Although knockout of MEC17 in the pyramidal neurons did not affect the density of the dendritic spines, it significantly aggravated the injury to them in the penumbra area and motor dysfunction after stroke. However, MEC17 upregulation in the pyramidal neurons and TBA treatment could maintain mature dendritic spine density and alleviate motor dysfunction after stroke.

CONCLUSION

Our study demonstrated that α-Ac-Tub plays a crucial role in the maintenance of the structure and functions of mature dendritic spines. Moreover, α-Ac-Tub protected the dendritic spines in the penumbra area and alleviated motor dysfunction after stroke.

Metformin enhances neural precursor cells migration and functional recovery after ischemic stroke in mice

Resident neural precursor cells (NPCs) activation is a promising therapeutic strategy for brain repair. This strategy involves stimulating multiple stages of NPCs development, including proliferation, self-renewal, migration, and differentiation. Metformin, an FDA-approved diabetes drug, has been shown to promote the proliferation and differentiation of NPCs. However, it is still unclear whether metformin promotes the migration of NPCs. EVOS living cell imaging system was used for observing the migration for primary NPCs dynamically in vitro after metformin treatment. For in vivo study, a mouse model of ischemic stroke was established through middle cerebral artery occlusion (MCAO). To label the proliferating cell in subventricular zone, BrdU was injected intraperitoneally into the mice. After co-staining with BrdU and doublecortin (DCX), a marker for NPCs, the migration of Brdu and DCX double positive NPCs was detected along the rostral migratory stream (RMS) and around the infarct area using frozen brain sections. Finally, the rotarod test, corner test and beam walking were performed to evaluate the motor functions of the mice after stroke in different groups. The results showed that metformin enhanced NPCs migration in vivo and in vitro by promoting F-actin assembly and lamellipodia formation. What's more, metformin treatment also significantly reduced the infarct volume and alleviated functional dysfunction after stroke. Mechanistically, metformin promoted NPCs migration via up-regulating the CDC42 expression. Taken together, metformin represents an optimal candidate agent for neural repair that is capable of not only expanding the adult NPC population but also subsequently driving them toward the destination for neuronal differentiation.

A novel aged mouse model of recurrent intracerebral hemorrhage in the bilateral striatum

The current animal models of stroke primarily model a single intracerebral hemorrhage (ICH) attack, and there is a lack of a reliable model of recurrent ICH. In this study, we established 16-month-old C57BL/6 male mouse models of ICH by injecting collagenase VII-S into the left striatum. Twenty-one days later, we injected collagenase VII-S into the right striatum to simulate recurrent ICH. Our results showed that mice subjected to bilateral striatal hemorrhage had poorer neurological function at the early stage of hemorrhage, delayed recovery in locomotor function, motor coordination, and movement speed, and more obvious emotional and cognitive dysfunction than mice subjected to unilateral striatal hemorrhage. These findings indicate that mouse models of bilateral striatal hemorrhage can well simulate clinically common recurrent ICH. These models should be used as a novel tool for investigating the pathogenesis and treatment targets of recurrent ICH.

Cyclophilin D-induced mitochondrial impairment confers axonal injury after intracerebral hemorrhage in mice

The mitochondrial permeability transition pore is a nonspecific transmembrane channel. Inhibition of mitochondrial permeability transition pore opening has been shown to alleviate mitochondrial swelling, calcium overload, and axonal degeneration. Cyclophilin D is an important component of the mitochondrial permeability transition pore. Whether cyclophilin D participates in mitochondrial impairment and axonal injury after intracerebral hemorrhage is not clear. In this study, we established mouse models of intracerebral hemorrhage in vivo by injection of autologous blood and oxyhemoglobin into the striatum in Thy1-YFP mice, in which pyramidal neurons and axons express yellow fluorescent protein. We also simulated intracerebral hemorrhage in vitro in PC12 cells using oxyhemoglobin. We found that axonal degeneration in the early stage of intracerebral hemorrhage depended on mitochondrial swelling induced by cyclophilin D activation and mitochondrial permeability transition pore opening. We further investigated the mechanism underlying the role of cyclophilin D in mouse models and PC12 cell models of intracerebral hemorrhage. We found that both cyclosporin A inhibition and short hairpin RNA interference of cyclophilin D reduced mitochondrial permeability transition pore opening and mitochondrial injury. In addition, inhibition of cyclophilin D and mitochondrial permeability transition pore opening protected corticospinal tract integrity and alleviated motor dysfunction caused by intracerebral hemorrhage. Our findings suggest that cyclophilin D is used as a key mediator of axonal degeneration after intracerebral hemorrhage; inhibition of cyclophilin D expression can protect mitochondrial structure and function and further alleviate corticospinal tract injury and motor dysfunction after intracerebral hemorrhage. Our findings provide a therapeutic target for preventing axonal degeneration of white matter injury and subsequent functional impairment in central nervous diseases.

Docosahexaenoic Acid Alleviates Brain Damage by Promoting Mitophagy in Mice with Ischaemic Stroke

Mitophagy, the selective removal of damaged mitochondria through autophagy, is crucial for mitochondrial turnover and quality control. Docosahexaenoic acid (DHA), an essential omega-3 fatty acid, protects mitochondria in various diseases. This study aimed to investigate the neuroprotective role of DHA in ischaemic stroke models in vitro and in vivo and its involvement in mitophagy and mitochondrial dysfunction. A mouse model of ischaemic stroke was established through middle cerebral artery occlusion (MCAO). To simulate ischaemic stroke in vitro, PC12 cells were subjected to oxygen–glucose deprivation (OGD). Immunofluorescence analysis, western blotting (WB), electron microscopy (EM), functional behavioural tests, and Seahorse assay were used for analysis. DHA treatment significantly alleviated the brain infarction volume, neuronal apoptosis, and behavioural dysfunction in mice with ischaemic stroke. In addition, DHA enhanced mitophagy by significantly increasing the number of autophagosomes and LC3-positive mitochondria in neurons. The Seahorse assay revealed that DHA increased glutamate and succinate metabolism in neurons after ischaemic stroke. JC-1 and MitoSox staining, and evaluation of ATP levels indicated that DHA-induced mitophagy alleviated reactive oxygen species (ROS) accumulation and mitochondrial injury. Mechanistically, DHA improved mitochondrial dynamics by increasing the expression of dynamin-related protein 1 (Drp1), LC3, and the mitophagy clearance protein Pink1/Parkin. Mdivi-1, a specific mitophagy inhibitor, abrogated the neuroprotective effects of DHA, indicating that DHA protected neurons by enhancing mitophagy. Therefore, DHA can protect against neuronal apoptosis after stroke by clearing the damaged mitochondria through Pink1/Parkin-mediated mitophagy and by alleviating mitochondrial dysfunction.

The interconnections between the microtubules and mitochondrial networks in cardiocerebrovascular diseases: Implications for therapy

Microtubules, a highly dynamic cytoskeleton, participate in many cellular activities including mechanical support, organelles interactions, and intracellular trafficking. Microtubule organization can be regulated by modification of tubulin subunits, microtubule-associated proteins (MAPs) or agents modulating microtubule assembly. Increasing studies demonstrate that microtubule disorganization correlates with various cardiocerebrovascular diseases including heart failure and ischemic stroke. Microtubules also mediate intracellular transport as well as intercellular transfer of mitochondria, a power house in cells which produce ATP for various physiological activities such as cardiac mechanical function. It is known to all that both microtubules and mitochondria participate in the progression of cancer and Parkinson's disease. However, the interconnections between the microtubules and mitochondrial networks in cardiocerebrovascular diseases remain unclear. In this paper, we will focus on the roles of microtubules in cardiocerebrovascular diseases, and discuss the interplay of mitochondria and microtubules in disease development and treatment. Elucidation of these issues might provide significant diagnostic value as well as potential targets for cardiocerebrovascular diseases.

Modulation of the proteoglycan receptor PTPσ promotes white matter integrity and functional recovery after intracerebral hemorrhage stroke in mice

Background

Intracerebral hemorrhage (ICH) is associated with high morbidity and mortality rates. However, extant investigations have mainly focused on gray matter injury within the primary injury site after ICH rather than on white matter (WM) injury in the brain and spinal cord. This focus partly accounts for the diminished therapeutic discovery. Recent evidence suggests that chondroitin sulphate proteoglycans (CSPG), which can bind to the neural transmembrane protein tyrosine phosphatase-sigma (PTPσ), may facilitate axonal regrowth and remyelination by ameliorating neuroinflammation.

Methods

A clinically relevant ICH model was established using adult C57BL/6 mice. The mice were then treated systemically with intracellular sigma peptide (ISP), which specifically targets PTPσ. Sensorimotor function was assessed by various behavioral tests and electrophysiological assessment. Western blot was used to verify the expression levels of Iba-1 and different inflammatory cytokines. The morphology of white matter tracts of brain and spinal cord was evaluated by immunofluorescence staining and transmission electron microscopy (TEM). Adeno-associated virus (AAV) 2/9 injection was used to assess the ipsilateral axonal compensation after injury. Parallel in vitro studies on the effects of CSPG interference on oligodendrocyte–DRG neuron co-culture explored the molecular mechanism through which ISP treatment promoted myelination capability.

Results

ISP, by targeting PTPσ, improved WM integrity and sensorimotor recovery via immunomodulation. In addition, ISP administration significantly decreased WM injury in the peri-hematomal region as well as cervical spinal cord, enhanced axonal myelination and facilitated neurological restoration, including electrophysiologically assessed sensorimotor functions. Parallel in vitro studies showed that inhibition of PTPσ by ISP fosters myelination by modulating the Erk/CREB signaling pathway.

Conclusions

Our findings revealed for the first time that manipulation of PTPσ signaling by ISP can promote prolonged neurological recovery by restoration of the integrity of neural circuits in the CNS through modulation of Erk/CREB signaling pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-022-02561-4.

HOXC6 Regulates the Epithelial-Mesenchymal Transition through the TGF-β/Smad Signaling Pathway and Predicts a Poor Prognosis in Glioblastoma

Background

The HOX gene family of transcription factors, characterized by conserved homeodomains, is positively correlated with the resistance to chemotherapy drugs and poor prognosis, as well as the initiating potential of gliomas. However, there are few studies regarding the HOXC6 gene in glioma cells. Therefore, in the present study, we explored the regulatory roles and detailed mechanisms underlying the relationship between HOXC6 and the progression of GBM.

Methods

The expression levels and prognostic value of HOXC6 in GBM were evaluated using the data obtained from the GCCA, GEPIA, and ONCOMINE databases. The relationship between GBM prognosis and levels of HOXC6 was identified using Kaplan-Meier curves. The protein levels of HOXC6 in GBM and adjacent normal tissues were identified via Western blot and immunohistochemistry (IHC) staining methods. Lentiviruses containing full-length HOXC6 and HOXC6 specific siRNA sequences were used to overexpress and knock down, respectively, the expression of HOXC6 in U87 and U251 cells. The role of HOXC6 in the regulation of migration and proliferation of GBM cells was accessed using Transwell, wound healing, CCK-8, and colony formation assays. The activation of the TGF-β/Smad signaling pathway was detected via Western blotting.

Results

Compared to normal tissues and control cells, GBM tissues and cell lines showed higher expressions of HOXC6. The expression of HOXC6 was associated with disease-free and the overall survival of GBM patients. Additionally, positive correlations between the expression of HOXC6 and the migration and proliferation of GBM cells were observed in vitro. The mechanistic analyses indicated that HOXC6 exerts its promotive effect on the progression and invasion of glioma cells by promoting the activation of the EMT and TGF-β/Smad signaling pathways.

Conclusions

HOXC6 enhances the migration and proliferation of GBM by activating the EMT signaling pathway.

Microtubules as Regulators of Neural Network Shape and Function: Focus on Excitability, Plasticity and Memory

Neuronal microtubules (MTs) are complex cytoskeletal protein arrays that undergo activity-dependent changes in their structure and function as a response to physiological demands throughout the lifespan of neurons. Many factors shape the allostatic dynamics of MTs and tubulin dimers in the cytosolic microenvironment, such as protein–protein interactions and activity-dependent shifts in these interactions that are responsible for their plastic capabilities. Recently, several findings have reinforced the role of MTs in behavioral and cognitive processes in normal and pathological conditions. In this review, we summarize the bidirectional relationships between MTs dynamics, neuronal processes, and brain and behavioral states. The outcomes of manipulating the dynamicity of MTs by genetic or pharmacological approaches on neuronal morphology, intrinsic and synaptic excitability, the state of the network, and behaviors are heterogeneous. We discuss the critical position of MTs as responders and adaptative elements of basic neuronal function whose impact on brain function is not fully understood, and we highlight the dilemma of artificially modulating MT dynamics for therapeutic purposes.

MEC17-induced α-tubulin acetylation restores mitochondrial transport function and alleviates axonal injury after intracerebral hemorrhage in mice

Injury to long axonal projections is a central pathological feature at the early phase of intracerebral hemorrhage (ICH). It has been reported to contribute to persistent functional disability following ICH. However, the molecular mechanisms that drive axonal degeneration remain unclear. Autologous blood was injected into the striatum to mimic the pathology of ICH. Observed significant swollen axons with characteristic retraction bulbs were found around the striatal hematoma at 24 h after ICH. Electronic microscopic examination revealed highly disorganized microtubule and swollen mitochondria in the retraction bulbs. MEC17 is a specific α-tubulin acetyltransferase, ablation of acetylated α-tubulin in MEC17^-/- mice aggravated axonal injury, axonal transport mitochondria dysfunction, and motor dysfunction. In contrast, treatment with tubastatin A (TubA), which promotes microtubule acetylation, significantly alleviated axonal injury and protected the integrity of the corticospinal tract and fine motor function after ICH. Moreover, results showed that 41% mitochondria were preferentially bundled to the acetylated α-tubulin in identifiable axons and dendrites in primary neurons. This impaired axonal transport of mitochondria in primary neurons of MEC17^-/- mice. Given that opening of mitochondrial permeability transition pore (mPTP) induces mitochondrial dysfunction and impairs ATP supply thereby promoting axonal injury, we enhanced the availability of acetylated α-tubulin using TubA and inhibited mPTP opening with cyclosporin A. The results indicated that this combined treatment synergistically protected corticospinal tract integrity and promoted fine motor control recovery. These findings reveal key intracellular mechanisms that drive axonal degeneration after ICH and highlight the need to target multiple factors and respective regulatory mechanisms as an effective approach to prevent axonal degeneration and motor dysfunction after ICH.

Ambroxol Upregulates Glucocerebrosidase Expression to Promote Neural Stem Cells Differentiation Into Neurons Through Wnt/β-Catenin Pathway After Ischemic Stroke

Ischemic stroke has been becoming one of the leading causes resulting in mortality and adult long-term disability worldwide. Post-stroke pneumonia is a common complication in patients with ischemic stroke and always associated with 1-year mortality. Though ambroxol therapy often serves as a supplementary treatment for post-stroke pneumonia in ischemic stroke patients, its effect on functional recovery and potential mechanism after ischemic stroke remain elusive. In the present study, the results indicated that administration of 70 mg/kg and 100 mg/kg enhanced functional recovery by virtue of decreasing infarct volume. The potential mechanism, to some extent, was due to promoting NSCs differentiation into neurons and interfering NSCs differentiation into astrocytes through increasing GCase expression to activate Wnt/β-catenin signaling pathway in penumbra after ischemic stroke, which advanced basic knowledge of ambroxol in regulating NSCs differentiation and provided a feasible therapy for ischemic stroke treatment, even in other brain disorders in clinic.

Efficacy of epothilones in central nervous system trauma treatment: what has age got to do with it?

Central nervous system injury, specifically traumatic brain and spinal cord injury, can have significant long lasting effects. There are no comprehensive treatments to combat the injury and sequalae of events that occurring following a central nervous system trauma. Herein we discuss the potential for the epothilone family of microtubule stabilizing agents to improve outcomes following experimentally induced trauma. These drugs, which are able to cross the blood-brain barrier, may hold great promise for the treatment of central nervous system trauma and the current literature presents the extensive range of beneficial effects these drugs may have following trauma in animal models. Importantly, the effect of the epothilones can vary and our most recent contributions to this field indicate that the efficacy of epothilones following traumatic brain injury is dependent upon the age of the animals. Therefore, we present a case for a greater emphasis to be placed upon age when using an intervention aimed at neural regeneration and highlight the importance of tailoring the therapeutic regime in the clinic to the age of the patient to promote improved patient outcomes.

Targeting CYP2J2 to Enhance the Anti-Glioma Efficacy of Cannabinoid Receptor 2 Stimulation by Inhibiting the Pro-Angiogenesis Function of M2 Microglia

Enhancing the therapeutic efficacy of anti-tumor drugs is essential for cancer management. Although cannabinoid receptor 2 (CB2R) stimulation exerts anti-tumor action in glioma cells by regulating cellular proliferation, differentiation, or apoptosis, selective CB2R agonist alone does not achieve a satisfactory therapeutic outcome. Herein, we aimed to evaluate the possible strategy for enhancing the anti-glioma efficacy of JWH133, a selective CB2R agonist. In this study, immunofluorescence and qRT-PCR were used to investigate microglia polarization. Tumor growth was monitored via bioluminescent imaging using the IVIS Spectrum System. The angiogenesis of human brain microvascular endothelial cells (HBMECs) was detected by the tube formation assay. qRT-PCR was used to investigate cytochrome P450 2J2 (CYP2J2) and 11,12-epoxyeicosatrienoic acid (11,12-EET) expression. Our results showed that administration of JWH133 significantly promoted microglial M2 polarization both in vitro and in vivo. The medium supernatant of M2 microglia induced by JWH133 treatment facilitated angiogenesis of HBMECs. CYP2J2 expression and 11,12-EET release in the supernatant of JWH133-induced M2 microglia were significantly upregulated. Treatment with 11,12-EET prompted HBMEC angiogenesis and glioma growth. CYP2J2 knockdown restrained the release of 11,12-EET and significantly enhanced the anti-tumor effect of JWH133 on glioma. This study showed that targeting CYP2J2 might be a beneficial strategy to enhance the anti-glioma efficacy of JWH133 by inhibiting the pro-angiogenesis function of M2 microglia.

Protracted Morphological Changes in the Corticospinal Tract Within the Cervical Spinal Cord After Intracerebral Hemorrhage in the Right Striatum of Mice

Intracerebral hemorrhage (ICH) is associated with high morbidity and mortality rates. Currently, there is no promising treatment that improves prognosis significantly. While a thorough investigation of the pathological process within the primary site of injury in the brain has been conducted by the research field, the focus was mainly on gray matter injury, which partly accounted for the failure of discovery of clinically efficacious treatments. It is not until recent years that white matter (WM) injury in the brain after subcortical ICH was examined. As WM tracts form networks between different regions, damage to fibers should impair brain connectivity, resulting in functional impairment. Although WM changes have been demonstrated in the brain after ICH, alterations distant from the initial injury site down in the spinal cord are unclear. This longitudinal study, for the first time, revealed prolonged morphological changes of the contralesional dorsal corticospinal tract (CST) in the spinal cord 5 weeks after experimental ICH in mice by confocal microscopy and transmission electron microscopy, implying that the structural integrity of the CST was compromised extensively after ICH. Given the important role of CST in motor function, future translational studies targeting motor recovery should delineate the treatment effects on CST integrity.

Epothilone B Facilitates Peripheral Nerve Regeneration by Promoting Autophagy and Migration in Schwann Cells

The search for drugs that can facilitate axonal regeneration and elongation following peripheral nerve injury has been an area of increasing interest in recent years. Epothilone B (EpoB) is an FDA-approved antineoplastic agent, which shows the capacity to induce α-tubulin polymerization and to improve the stability of microtubules. Recently, it has been increasingly recognized that EpoB has a regenerative effect in the central nervous system. However, the information currently available regarding the potential therapeutic effect of EpoB on peripheral nerve regeneration is limited. Here, we used a rat sciatic crush injury model system to determine that EpoB strikingly improved axonal regeneration and recovery of function. Also, EpoB (1 nM) did not result in significant apoptosis in Schwann cells (SCs) and showed little effect on their viability either. Interestingly, EpoB (1 nM) significantly enhanced migration in SCs, which was inhibited by autophagy inhibitors 3-methyladenine (3-MA). Since PI3K/Akt signaling has been implicated in regulating autophagy, we further examined the involvement of PI3K/Akt in the process of EpoB-induced SC migration. We found that EpoB (1 nM) significantly inhibited phosphorylation of PI3K and Akt in SCs. Further studies showed that both EpoB-enhanced migration and autophagy were increased/inhibited by inhibition/activation of PI3K/Akt signaling with LY294002 or IGF-1. In conclusion, EpoB can promote axonal regeneration following peripheral nerve injury by enhancing the migration of SCs, with this activity being controlled by PI3K/Akt signaling-mediated autophagy in SCs. This underscores the potential therapeutic value of EpoB in enhancing regeneration and functional recovery in cases of peripheral nerve injury.

Artesunate promotes the proliferation of neural stem/progenitor cells and alleviates Ischemia-reperfusion Injury through PI3K/Akt/FOXO-3a/p27kip1 signaling pathway

Stroke is one of the leading causes of death worldwide that also result in long-term disability. Endogenous neural stem/progenitor cells (NSPCs) within subventricular (SVZ) and dentate gyrus (DG) zone, stimulated by cerebral infarction, can promote neural function recovery. However, the proliferation of eNSPCs triggered by ischemia is not enough to induce neural repair, which may contribute to the permanent disability in stroke patients. In this study, our results showed that following the treatment with artesunate (ART, 150 mg/kg), the functional recovery was significantly improved, the infarct volume was notably reduced, and the expression of Nestin, a proliferation marker of NSPCs in the infarcted cortex, was also increased. Additionally, the proliferative activity of NSPCs with or without oxygen-glucose deprivation/reperfusion was significantly promoted by ART treatment, and the therapeutic concentration was 0.8 μmol/L (without OGD/R) or 0.4 μmol/L (with OGD/R) in the in vitro model. Furthermore, the effects of ART can be abolished by the treatment of PI3K inhibitor wortmannin. The expression levels of related molecules in PI3K/Akt/FOXO-3a/p27^kip1 signaling pathway (p-AKT, p-FOXO-3a, p27^kip1) were examined using western blotting. The results suggested ART could inhibit the transcriptional function of FOXO-3a by inducing its phosphorylation, subsequently downregulating p27^kip1 and enhancing neural stem cell proliferation in the infarcted cortex via PI3K/AKT signaling, further alleviating ischemia-reperfusion injury after ischemic stroke.

Ambroxol Improves Neuronal Survival and Reduces White Matter Damage through Suppressing Endoplasmic Reticulum Stress in Microglia after Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) has been becoming a serious public health problem. Pneumonia, occurring in 43% of all ICH patients, is a common complication heavily influencing outcome and accounting for more than 1/3 of the overall mortality in patients with ICH. Ambroxol may be an effective additional treatment for ICH patients with pneumonia. But its effect and potential mechanism on functional recovery post-ICH still remain elusive. In the present study, the results indicated that 35 mg/kg and 70 mg/kg ambroxol facilitated neuronal survival and reduced white matter fiber bundle damage due to mitigating microglial activation and reducing proinflammatory cytokine accumulation in mice with ICH. The possible mechanism might be due to suppressing endoplasmic reticulum stress involving the IRE1α/TRAF2 signaling pathway, which paves a new path for the treatment of ICH and opens a new window for the use of ambroxol in clinical practice.

Naturally Occurring Antibodies to Tau Exists in Human Blood and Are Not Changed in Alzheimer's Disease

Hyperphosphorylated tau is an important pathological agent in Alzheimer's disease (AD). Tau effluxes from the brain to the blood could potentially stimulate the production of naturally occurring antibodies (NAbs). We aimed to investigate whether NAbs to tau (NAbs-tau) was generated in human blood and to figure out the alteration of plasma NAbs-tau level in AD patients. About 192 AD patients and 192 age-matched and non-demented controls (NC) were enrolled in the present study. Immunofluorescence staining and western blot assays were used to confirm the existence of NAbs-tau in human blood. The plasma level of NAbs-tau in NC and AD group was analyzed by ELISA. Immunofluorescence staining and western blot assays confirmed the existence of NAbs-tau in human blood. However, no significant difference in the plasma level of NAbs-tau was observed between NC and AD group. Furthermore, the plasma level of NAbs-tau had no significant correlation with MMSE scores. The present study confirmed that NAbs-tau exists in human blood but does not differ in level between the NC and AD group. Plasma NAbs-tau is not a reliable biomarker for AD.

Quantitative Iron Neuroimaging Can Be Used to Assess the Effects of Minocycline in an Intracerebral Hemorrhage Minipig Model

Iron-mediated toxicity is a key factor causing brain injury after intracerebral hemorrhage (ICH). This study was performed to investigate the noninvasive neuroimaging method for quantifying brain iron content using a minipig ICH model and assess the effects of minocycline treatment on ICH-induced iron overload and brain injury. The minipig ICH model was established by injecting 2 ml of autologous blood into the right basal ganglia, which were then subjected to the treatments of minocycline and vehicle. Furthermore, the quantitative susceptibility mapping (QSM) was used to quantify iron content, and diffusion tensor imaging (DTI) was performed to evaluate white matter tract. Additionally, we also performed immunohistochemistry, Western blot, iron assay, Perl's staining, brain water content, and neurological score to evaluate the iron overload and brain injury. Interestingly, we found that the ICH-induced iron overload could be accurately quantified by the QSM. Moreover, the minocycline was quite beneficial for protecting brain injury by reducing the lesion volume and brain edema, preventing brain iron accumulation, downsizing ventricle enlargement, and alleviating white matter injury and neurological deficits. In summary, we suggest that the QSM be an accurate and noninvasive method for quantifying brain iron level, and the minocycline may be a promising therapeutic agent for patients with ICH.

SVCT2 Promotes Neural Stem/Progenitor Cells Migration Through Activating CDC42 After Ischemic Stroke

Ischemic stroke is one of the most leading diseases causing death/long-term disability worldwide. Activating endogenous neural stem/progenitors cells (NSPCs), lining in the subventricular zone (SVZ) and dentate gyrus, facilitates injured brain tissue recovery in both short and long-term experimental settings. While, only a few proliferated NSPCs migrate toward the lesions to enhance endogenous repair after ischemia. Here, the results indicated that the functional recovery was evidently improved and the infarct volume was significantly reduced with ascorbic acid (AA) treatment in a dose-dependent manner from 125 to 500 mg/Kg, and the suitable therapeutic concentration was 250 mg/Kg. The possible mechanism might be due to activating sodium-vitamin C cotransporter 2 (SVCT2), which was down-regulated in SVZ after ischemia. Furthermore, immunostaining images depicted the number of migrated NSPCs from SVZ were significantly increased with 250 mg/Kg AA treatment or SVCT2 overexpression under the physiological and pathological condition in vivo. Besides, the data also represented that 250 mg/Kg AA or SVCT2 overexpression facilitated NSPCs migration via promoting F-actin assembling in the manner of up-regulating CDC42 expression using oxygen-glucose deprivation in vitro. Collectively, the present study indicates that SVCT2 promotes NSPCs migration through CDC42 activation to facilitate F-actin assembling, which enlarges the therapeutic scope of AA and the role of SVCT2 in NSPCs migration after brain injury.

Lactobacillus acidophilus Exerts Neuroprotective Effects in Mice with Traumatic Brain Injury

BACKGROUND

Traumatic brain injury (TBI) causes dysbiosis and intestinal barrier disruption, which further exacerbate brain damage via an inflammatory pathway. Gut microbiota remodeling by Lactobacillus acidophilus (LA) is a potential intervention.

OBJECTIVE

The aim of this study was to investigate the neuroprotective effects of LA in TBI and elucidated underlying mechanisms.

METHODS

C57BL/6 male mice (aged 8-9 wk) were subjected to weight-drop impact and gavaged with saline (TBI + vehicle) or LA (1 × 1010 CFU) (TBI + LA) on the day of injury and each day after for 1, 3, or 7 d. The sham + vehicle mice underwent craniotomy without brain injury and were gavaged with saline. Sensorimotor functions were determined pre-TBI and 1, 3, and 7 d postinjury. Indexes of neuroinflammation, peripheral inflammation, and intestinal barrier function were measured on days 3 and 7. Microbiota composition was measured 3 d postinjury. The data were mainly analyzed by 2-factor ANOVA.

RESULTS

Compared with sham + vehicle mice, the TBI + vehicle mice exhibited impairments in the neurological severity score (+692%, day 3; +600%, day 7) and rotarod test (-58%, day 3; -45%, day 7) (P < 0.05), which were rescued by LA. The numbers of microglia (total and activated) and astrocytes and concentrations of TNF-α and IL1-β in the perilesional cortex were elevated in the TBI + vehicle mice on day 3 or 7 compared with sham + vehicle mice (P < 0.05) and were normalized by LA. Compared with sham + vehicle mice, the TBI + vehicle mice exhibited increased serum concentrations of endotoxin and TNF-α, and intestinal barrier permeability (D-lactate) on days 3 and 7 (P < 0.05), and these changes were alleviated by LA. Three days postinjury, the microbiota composition was disrupted in the TBI + vehicle mice compared with sham + vehicle mice (P < 0.05), which was restored by LA.

CONCLUSION

Our results demonstrate that LA exerts neuroprotective effects that may be associated with gut microbiota remodeling in TBI mice.

TRPA1 Activation-Induced Myelin Degradation Plays a Key Role in Motor Dysfunction After Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a devastating disease that is characterized by high morbidity and high mortality. ICH has an annual incidence of 10-30/100,000 people and accounts for approximately 10%-30% of all types of stroke. ICH mostly occurs at the basal ganglia, which is rich in nerve fibers; thus, hemiplegia is quite common in ICH patients with partial sensory disturbance and ectopic blindness. In the clinic, those symptoms are considered to originate from the white matter injury in the area, but the exact mechanisms are unknown, and currently, no effective drug treatments are available to improve the prognosis. Clarifying the mechanisms will contribute to the development of new treatment methods for patients. The transient receptor potential ankyrin 1 (TRPA1) channel is a non-selective cation channel that plays a role in inflammatory pain sensation and nociception and may be a potential regulator in emotion, cognition and social behavior. Here, we report that TRPA1 is involved in myelin damage and oxidative stress injury in a mouse ICH model. Intervention with the TRPA1 channel may be a new method to improve the motor function of patients in the early stage of ICH.

Knockdown of Fidgetin Improves Regeneration of Injured Axons by a Microtubule-Based Mechanism

Fidgetin is a microtubule-severing protein that pares back the labile domains of microtubules in the axon. Experimental depletion of fidgetin results in elongation of the labile domains of microtubules and faster axonal growth. To test whether fidgetin knockdown assists axonal regeneration, we plated dissociated adult rat DRGs transduced using AAV5-shRNA-fidgetin on a laminin substrate with spots of aggrecan, a growth-inhibitory chondroitin sulfate proteoglycan. This cell culture assay mimics the glial scar formed after CNS injury. Aggrecan is more concentrated at the edge of the spot, such that axons growing from within the spot toward the edge encounter a concentration gradient that causes growth cones to become dystrophic and axons to retract or curve back on themselves. Fidgetin knockdown resulted in faster-growing axons on both laminin and aggrecan and enhanced crossing of axons from laminin onto aggrecan. Strikingly, axons from within the spot grew more avidly against the inhibitory aggrecan concentration gradient to cross onto laminin, without retracting or curving back. We also tested whether depleting fidgetin improves axonal regeneration in vivo after a dorsal root crush in adult female rats. Whereas control DRG neurons failed to extend axons across the dorsal root entry zone after injury, DRG neurons in which fidgetin was knocked down displayed enhanced regeneration of axons across the dorsal root entry zone into the spinal cord. Collectively, these results establish fidgetin as a novel therapeutic target to augment nerve regeneration and provide a workflow template by which microtubule-related targets can be compared in the future.SIGNIFICANCE STATEMENT Here we establish a workflow template from cell culture to animals in which microtubule-based treatments can be tested and compared with one another for their effectiveness in augmenting regeneration of injured axons relevant to spinal cord injury. The present work uses a viral transduction approach to knock down fidgetin from rat neurons, which coaxes nerve regeneration by elevating microtubule mass in their axons. Unlike previous strategies using microtubule-stabilizing drugs, fidgetin knockdown adds microtubule mass that is labile (rather than stable), thereby better recapitulating the growth status of a developing axon.

Epothilone B Benefits Nigral Dopaminergic Neurons by Attenuating Microglia Activation in the 6-Hydroxydopamine Lesion Mouse Model of Parkinson's Disease

Parkinson’s disease (PD) is characterized by loss of dopamine (DA) neurons in the substantia nigra pars compacta (SNc) and a subsequent reduction in striatal DA levels. Recent studies have shown that systemic administration of subtoxic doses of epothilone B (EpoB), a microtubule stabilizing agent, enhances axonal regeneration. However, the underlying alterations in cellular mechanisms remain undetermined. In the present study, we investigated the neuroprotective effects of EpoB on DA neurons in mouse model of PD induced by 6-hydroxyDA (6-OHDA) and in vitro. The results indicated that EpoB improved behavioral deficits, protected the nigrostriatal dopaminergic projections and restored DA level in the striatum of mice exposed to 6-OHDA. Meanwhile, EpoB attenuated microglia activation in the SNc of PD mice. Furthermore, EpoB treatment ameliorated 6-OHDA induced cytotoxicity to MN9D dopaminergic cells in a co-culture transwell system of BV2/MN9D cells, and redistributed the cytoskeleton of microglial BV2 and caused the morphological transition, inhibited the polarization to the M1 phenotype by suppressing expression of pro-inflammatory factors including interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF)-α. Overall, our study suggested that EpoB treatment protects nigral DA neurons and projections through limiting the cytotoxicity of activated microglia in 6-OHDA lesioned mice.

Stably maintained microtubules protect dopamine neurons and alleviate depression-like behavior after intracerebral hemorrhage

Mesolimbic dopamine (DA) system lesion plays a key role in the pathophysiology of depression, and our previous study demonstrated that reduced microtubule (MT) stability aggravated nigrostriatal pathway impairment after intracerebral hemorrhage (ICH). This study aimed to further investigate the occurrence regularity of depression-like behavior after ICH and determine whether maintaining MT stabilization could protect DA neurons in ventral tegmental area (VTA) and alleviate depression-like behavior after ICH. An intrastriatal injection of 20 μl of autologous blood or MT depolymerization reagent nocodazole (Noco) was used to mimic the pathology of ICH model in mice. The concentration of DA, number of DA neurons and acetylated α-tubulin (a marker for stable MT) in VTA were checked, and depression-related behavior tests were performed after ICH. A MT-stabilizing agent, epothilone B (EpoB), was administered to explore the effects of MT stabilization on DA neurons and depression-like behavior after ICH. The results showed that obvious depression-like behavior occurred at 7, 14, and 28 days (P < 0.01) after ICH. These time-points were related to significant decreases in the concentration of DA (P < 0.01) and number of DA neurons (P < 0.01) in VTA. Moreover, The decrease of acetylated α-tubulin expression after ICH and Noco injection contributed to DA neurons' impairment in VTA, and Noco injecton also aggravate ICH-induced depression-like behaviors and DA neurons' injury. Furthermore, EpoB treatment significantly ameliorated ICH and Noco-induced depression-like behaviors (P < 0.05) and increased the concentration of DA (P < 0.05) and number of DA neurons (P < 0.05) in VTA by increasing the level of acetylated α-tubulin. The results indicate that EpoB can protect DA neurons by enhancing MT stability, and alleviate post-ICH depressive behaviors. This MT-targeted therapeutic strategy shows promise as a bench-to-bedside translational method for treating depression after ICH.