Cofilin Inhibition Restores Neuronal Cell Death in Oxygen-Glucose Deprivation Model of Ischemia

Age-dependent sex differences in cofilin1 pathway (LIMK1/SSH1) and its association with AD biomarkers after chronic systemic inflammation in mice

Chronic systemic inflammation (CSI) results in neuroinflammation and neurodegeneration. Cofilin1 is a stress protein that activates microglia and induces neuroinflammation, but its role in CSI at different aging stages remains unidentified. Therefore, the study aims to identify cofilin1 and its upstream regulators LIMK1 and SSH1 after CSI in young-, middle-, and advanced-aged mice. CSI was induced by injecting the male and female mice with a sub-lethal dose of Lipopolysaccharide weekly for six weeks. The results showed that normal male mice did not show cofilin pathway dysregulation, but a significant dysregulation was observed in CSI advanced-aged mice. In females, cofilin1 dysregulation was observed in healthy and CSI advanced-aged mice, while significant cofilin1 dysregulation was observed in middle-aged mice during CSI. Furthermore, cofilin1 pathway dysregulations correlated with Alzheimer's disease (AD) biomarkers in the brain and saliva, astrocyte activation, synaptic degeneration, neurobehavioral impairments, gut-microbiota abnormalities, and circulatory inflammation. These results provide new insights into cofilin1 sex and age-dependent mechanistic differences that might help identify targets for modulating neuroinflammation and early onset of AD.

α-Synuclein-mediated mitochondrial translocation of cofilin-1 leads to oxidative stress and cell apoptosis in PD

Parkinson's disease (PD) is characterized by the accumulation of misfolded α-synuclein protein and the loss of dopaminergic neurons in the substantia nigra. Abnormal α-synuclein aggregates form toxic Lewy bodies, ultimately inducing neuronal injury. Mitochondrial dysfunction was reported to be involved in the neurotoxicity of α-synuclein aggregates in PD. However, the specific mechanism by which abnormal α-synuclein aggregates cause mitochondrial disorders remains poorly defined. Previously, we found that cofilin-1, a member of the actin-binding protein, regulates α-synuclein pathogenicity by promoting its aggregation and spreading in vitro and in vivo. In this study, we further investigated the effect of cofilin-1 on α-synuclein induced mitochondrial damage. We discovered that α-synuclein aggregates accelerate the translocation of cofilin-1 to mitochondria, promote its combination with the mitochondrial outer membrane receptor Tom 20, and ultimately activate the oxidative damage and apoptosis pathway in mitochondria. All these results demonstrate the important regulatory role of cofilin-1 in the mitochondrial neurotoxicity of pathological α-synuclein during the progression of PD.

The Multifaceted Role of Cofilin in Neurodegeneration and Stroke: Insights into Pathogenesis and Targeting as a Therapy

This comprehensive review explores the complex role of cofilin, an actin-binding protein, across various neurodegenerative diseases (Alzheimer's, Parkinson's, schizophrenia, amyotrophic lateral sclerosis (ALS), Huntington's) and stroke. Cofilin is an essential protein in cytoskeletal dynamics, and any dysregulation could lead to potentially serious complications. Cofilin's involvement is underscored by its impact on pathological hallmarks like Aβ plaques and α-synuclein aggregates, triggering synaptic dysfunction, dendritic spine loss, and impaired neuronal plasticity, leading to cognitive decline. In Parkinson's disease, cofilin collaborates with α-synuclein, exacerbating neurotoxicity and impairing mitochondrial and axonal function. ALS and frontotemporal dementia showcase cofilin's association with genetic factors like C9ORF72, affecting actin dynamics and contributing to neurotoxicity. Huntington's disease brings cofilin into focus by impairing microglial migration and influencing synaptic plasticity through AMPA receptor regulation. Alzheimer's, Parkinson's, and schizophrenia exhibit 14-3-3 proteins in cofilin dysregulation as a shared pathological mechanism. In the case of stroke, cofilin takes center stage, mediating neurotoxicity and neuronal cell death. Notably, there is a potential overlap in the pathologies and involvement of cofilin in various diseases. In this context, referencing cofilin dysfunction could provide valuable insights into the common pathologies associated with the aforementioned conditions. Moreover, this review explores promising therapeutic interventions, including cofilin inhibitors and gene therapy, demonstrating efficacy in preclinical models. Challenges in inhibitor development, brain delivery, tissue/cell specificity, and long-term safety are acknowledged, emphasizing the need for precision drug therapy. The call to action involves collaborative research, biomarker identification, and advancing translational efforts. Cofilin emerges as a pivotal player, offering potential as a therapeutic target. However, unraveling its complexities requires concerted multidisciplinary efforts for nuanced and effective interventions across the intricate landscape of neurodegenerative diseases and stroke, presenting a hopeful avenue for improved patient care.

Cofilin Inhibitor Improves Neurological and Cognitive Functions after Intracerebral Hemorrhage by Suppressing Endoplasmic Reticulum Stress Related-Neuroinflammation

Neuroinflammation after intracerebral hemorrhage (ICH) is a crucial factor that determines the extent of the injury. Cofilin is a cytoskeleton-associated protein that drives neuroinflammation and microglia activation. A novel cofilin inhibitor (CI) synthesized and developed in our lab has turned out to be a potential therapeutic agent for targeting cofilin-mediated neuroinflammation in an in vitro model of ICH and traumatic brain injury. The current study aims to examine the therapeutic potential of CI in a mouse collagenase model of ICH and examine the neurobehavioral outcomes and its mechanism of action. Male mice were subjected to intrastriatal collagenase injection to induce ICH, and sham mice received needle insertion. Various concentrations (25, 50, and 100 mg/kg) of CI were administered to different cohorts of the animals as a single intravenous injection 3 h following ICH and intraperitoneally every 12 h for 3 days. The animals were tested for neurobehavioral parameters for up to 7 days and sacrificed to collect brains for hematoma volume measurement, Western blotting, and immunohistochemistry. Blood was collected for cofilin, TNF-α, and IL-1β assessments. The results indicated that 50 mg/kg CI improved neurological outcomes, reversed post-stroke cognitive impairment, accelerated hematoma resolution, mitigated cofilin rods/aggregates, and reduced microglial and astrocyte activation in mice with ICH. Microglia morphological analysis demonstrated that CI restored the homeostasis ramification pattern of microglia in mice treated with CI. CI suppressed endoplasmic reticulum stress-related neuroinflammation by inhibiting inflammasomes and cell death signaling pathways. We also showed that CI prevented synaptic loss by reviving the pre- and post-synaptic markers. Our results unveil a novel therapeutic approach to treating ICH and open a window for using CI in clinical practice.

Resveratrol Preconditioning Protects Against Ischemia-Induced Synaptic Dysfunction and Cofilin Hyperactivation in the Mouse Hippocampal Slice

Perturbations in synaptic function are major determinants of several neurological diseases and have been associated with cognitive impairments after cerebral ischemia (CI). Although the mechanisms underlying CI-induced synaptic dysfunction have not been well defined, evidence suggests that early hyperactivation of the actin-binding protein, cofilin, plays a role. Given that synaptic impairments manifest shortly after CI, prophylactic strategies may offer a better approach to prevent/mitigate synaptic damage following an ischemic event. Our laboratory has previously demonstrated that resveratrol preconditioning (RPC) promotes cerebral ischemic tolerance, with many groups highlighting beneficial effects of resveratrol treatment on synaptic and cognitive function in other neurological conditions. Herein, we hypothesized that RPC would mitigate hippocampal synaptic dysfunction and pathological cofilin hyperactivation in an ex vivo model of ischemia. Various electrophysiological parameters and synaptic-related protein expression changes were measured under normal and ischemic conditions utilizing acute hippocampal slices derived from adult male mice treated with resveratrol (10 mg/kg) or vehicle 48 h prior. Remarkably, RPC significantly increased the latency to anoxic depolarization, decreased cytosolic calcium accumulation, prevented aberrant increases in synaptic transmission, and rescued deficits in long-term potentiation following ischemia. Additionally, RPC upregulated the expression of the activity-regulated cytoskeleton associated protein, Arc, which was partially required for RPC-mediated attenuation of cofilin hyperactivation. Taken together, these findings support a role for RPC in mitigating CI-induced excitotoxicity, synaptic dysfunction, and pathological over-activation of cofilin. Our study provides further insight into mechanisms underlying RPC-mediated neuroprotection against CI and implicates RPC as a promising strategy to preserve synaptic function after ischemia.

Impaired Insulin Signaling Alters Mediators of Hippocampal Synaptic Dynamics/Plasticity: A Possible Mechanism of Hyperglycemia-Induced Cognitive Impairment

Alzheimer's disease (AD) is a neurological condition that affects the elderly and is characterized by progressive and irreversible neurodegeneration in the cerebral cortex [...].

Cofilin Inhibitor Protects against Traumatic Brain Injury-Induced Oxidative Stress and Neuroinflammation

Microglial activation and failure of the antioxidant defense mechanisms are major hallmarks in different brain injuries, particularly traumatic brain injury (TBI). Cofilin is a cytoskeleton-associated protein involved in actin binding and severing. In our previous studies, we identified the putative role of cofilin in mediating microglial activation and apoptosis in ischemic and hemorrhagic conditions. Others have highlighted the involvement of cofilin in ROS production and the resultant neuronal death; however, more studies are needed to delineate the role of cofilin in oxidative stress conditions. The present study aims to investigate the cellular and molecular effects of cofilin in TBI using both in vitro and in vivo models as well as the first-in-class small-molecule cofilin inhibitor (CI). An in vitro H2O2-induced oxidative stress model was used in two different types of cells, human neuroblastoma (SH-SY5Y) and microglia (HMC3), along with an in vivo controlled cortical impact model of TBI. Our results show that treatment with H2O2 increases the expression of cofilin and slingshot-1 (SSH-1), an upstream regulator of cofilin, in microglial cells, which was significantly reduced in the CI-treated group. Cofilin inhibition significantly attenuated H2O2-induced microglial activation by reducing the release of proinflammatory mediators. Furthermore, we demonstrate that CI protects against H2O2-induced ROS accumulation and neuronal cytotoxicity, activates the AKT signaling pathway by increasing its phosphorylation, and modulates mitochondrial-related apoptogenic factors. The expression of NF-E2-related factor 2 (Nrf2) and its associated antioxidant enzymes were also increased in CI-treated SY-SY5Y. In the mice model of TBI, CI significantly activated the Nrf2 and reduced the expression of oxidative/nitrosative stress markers at the protein and gene levels. Together, our data suggest that cofilin inhibition provides a neuroprotective effect in in vitro and in vivo TBI mice models by inhibiting oxidative stress and inflammatory responses, the pivotal mechanisms involved in TBI-induced brain damage.

Spatiotemporal Cofilin Signaling, Microglial Activation, Neuroinflammation, and Cognitive Impairment Following Hemorrhagic Brain Injury

Intracerebral hemorrhage (ICH) is a significant health concern associated with high mortality. Cofilin plays a crucial role in stress conditions, but its signaling following ICH in a longitudinal study is yet to be ascertained. In the present study, we examined the cofilin expression in human ICH autopsy brains. Then, the spatiotemporal cofilin signaling, microglia activation, and neurobehavioral outcomes were investigated in a mouse model of ICH. Human autopsy brain sections from ICH patients showed increased intracellular cofilin localization within microglia in the perihematomal area, possibly associated with microglial activation and morphological changes. Various cohorts of mice were subjected to intrastriatal collagenase injection and sacrificed at time points of 1, 3, 7, 14, 21, and 28 days. Mice suffered from severe neurobehavioral deficits after ICH, lasting for 7 days, followed by a gradual improvement. Mice suffered post-stroke cognitive impairment (PSCI) both acutely and in the chronic phase. Hematoma volume increased from day 1 to 3, whereas ventricle size increased from day 21 to 28. Cofilin protein expression increased in the ipsilateral striatum on days 1 and 3 and then decreased from days 7 to 28. An increase in activated microglia was observed around the hematoma on days 1 to 7, followed by a gradual reduction up to day 28. Around the hematoma, activated microglia showed morphological changes from ramified to amoeboid. mRNA levels of inflammatory [tumor necrosis factor-α (TNF-α), interleukin 1β (IL-1β), and interleukin-6 (IL-6) and anti-inflammatory markers [interleukin-10 (IL-10), transforming growth factor-β TGF-β, and arginase I (Arg1)] increased during the acute phase and decreased in the chronic phase. Blood cofilin levels increased on day 3 and matched the increase in chemokine levels. slingshot protein phosphatase 1 (SSH1) protein, which activates cofilin, was increased from day 1 to 7. These results suggest that microglial activation might be the sequel of cofilin overactivation following ICH, leading to widespread neuroinflammation and consequent PSCI.

Development and validation of LC-MS/MS method for determining the metabolic stability, pharmacokinetics, and dose proportionality of a novel anti-inflammatory cofilin inhibitor

A novel small molecule cofilin inhibitor (SZ-3) has recently become the focus of investigation for targeting neuroinflammation in different neurodegenerative diseases. In the present study, the metabolic stability, blood-brain barrier (BBB) penetration, and tissue concentration of SZ-3 were evaluated to support our future studies. In silico drug metabolism prediction was investigated using the StarDrop WhichP450 module. LC-MS/MS method was developed and validated to quantify the SZ-3 for in-vitro and in-vivo studies. The in-vitro metabolic stability was performed using human liver microsomes (HLMs), and the in-vivo pharmacokinetics were investigated in mice after a single intraperitoneal (IP) injection or oral (P.O.) administration, followed by a collection of blood and brain samples at different time points. The dose-proportionality was also evaluated after a single IP injection of three ascending doses (5, 10, and 25 mg/kg). In-vitro results showed that SZ-3 has a moderate intrinsic clearance (Clint) value of 17.42 ml/min/mg with a half-life (t1/2) value of 39.77 mins, indicative of good bioavailability. In vivo study revealed that SZ-3 was rapidly absorbed, entered the brain, and yielded a good concentration of the unbound drug after IP and oral administration. However, the higher maximum concentration (Cmax) values of IP and P.O. (2244 ng/ml and 1069 ng/g, respectively) revealed that the IP administration led to higher blood and brain concentrations than the P.O. Furthermore, Cmax and area under the curve (AUC) of SZ-3 increased in a dose-proportional manner between the three ascending doses. These results will guide us in optimizing the dosing regimen for future SZ-3 pharmacological studies targeting neuroinflammation.

Engineering Extracellular Vesicles to Modulate Their Innate Mitochondrial Load

Introduction

Extracellular vesicles (EVs) are promising carriers for the delivery of biotherapeutic cargo such as RNA and proteins. We have previously demonstrated that the innate EV mitochondria in microvesicles (MVs), but not exosomes (EXOs) can be transferred to recipient BECs and mouse brain slice neurons. Here, we sought to determine if the innate EV mitochondrial load can be further increased via increasing mitochondrial biogenesis in the donor cells. We hypothesized that mitochondria-enriched EVs ("mito-EVs") may increase the recipient BEC ATP levels to a greater extent than naïve MVs.

Methods

We treated NIH/3T3, a fibroblast cell line and hCMEC/D3, a human brain endothelial cell (BEC) line using resveratrol to activate peroxisome proliferator-activated receptor-gamma coactivator-1α (PGC-1α), the central mediator of mitochondrial biogenesis. Naïve EVs and mito-EVs isolated from the non-activated and activated donor cells were characterized using transmission electron microscopy, dynamic light scattering and nanoparticle tracking analysis. The effect of mito-EVs on resulting ATP levels in the recipient BECs were determined using Cell Titer Glo ATP assay. The uptake of Mitotracker Red-stained EVs into recipient BECs and their colocalization with recipient BEC mitochondria were studied using flow cytometry and fluorescence microscopy.

Results

Resveratrol treatment increased PGC-1α expression in the donor cells. Mito-MVs but not mito-EXOs showed increased expression of mitochondrial markers ATP5A and TOMM20 compared to naïve MVs. TEM images showed that a greater number of mito-MVs contained mitochondria compared to naïve MVs. Mito-MVs but not mito-EXOs showed a larger particle diameter compared to their naïve EV counterparts from the non-activated cells suggesting increased mitochondria incorporation. Mito-EVs were generated at higher particle concentrations compared to naïve EVs from non-activated cells. Mito-EVs increased the cellular ATP levels and transferred their mitochondrial load into the recipient BECs. Mito-MV mitochondria also colocalized with recipient BEC mitochondria.

Conclusions

Our results suggest that the pharmacological modulation of mitochondrial biogenesis in the donor cells can change the mitochondrial load in the secreted MVs. Outcomes of physicochemical characterization studies and biological assays confirmed the superior effects of mito-MVs compared to naïve MVs-suggesting their potential to improve mitochondrial function in neurovascular and neurodegenerative diseases.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12195-022-00738-8.

Cytoskeletal dysregulation and neurodegenerative disease: Formation, monitoring, and inhibition of cofilin-actin rods

The presence of atypical cytoskeletal dynamics, structures, and associated morphologies is a common theme uniting numerous diseases and developmental disorders. In particular, cytoskeletal dysregulation is a common cellular feature of Alzheimer’s disease, Parkinson’s disease, and Huntington’s disease. While the numerous activators and inhibitors of dysregulation present complexities for characterizing these elements as byproducts or initiators of the disease state, it is increasingly clear that a better understanding of these anomalies is critical for advancing the state of knowledge and plan of therapeutic attack. In this review, we focus on the hallmarks of cytoskeletal dysregulation that are associated with cofilin-linked actin regulation, with a particular emphasis on the formation, monitoring, and inhibition of cofilin-actin rods. We also review actin-associated proteins other than cofilin with links to cytoskeleton-associated neurodegenerative processes, recognizing that cofilin-actin rods comprise one strand of a vast web of interactions that occur as a result of cytoskeletal dysregulation. Our aim is to present a current perspective on cytoskeletal dysregulation, connecting recent developments in our understanding with emerging strategies for biosensing and biomimicry that will help shape future directions of the field.

Synthesis and Development of a Novel First-in-Class Cofilin Inhibitor for Neuroinflammation in Hemorrhagic Brain Injury

Intracerebral hemorrhage (ICH) is devastating among stroke types with high mortality. To date, not a single therapeutic intervention has been successful. Cofilin plays a critical role in inflammation and cell death. In the current study, we embarked on designing and synthesizing a first-in-class small-molecule inhibitor of cofilin to target secondary complications of ICH, mainly neuroinflammation. A series of compounds were synthesized, and two lead compounds SZ-3 and SK-1-32 were selected for further studies. Neuronal and microglial viabilities were assessed by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay using neuroblastoma (SHSY-5Y) and human microglial (HMC-3) cell lines, respectively. Lipopolysaccharide (LPS)-induced inflammation in HMC-3 cells was used for neurotoxicity assay. Other assays include nitric oxide (NO) by Griess reagent, cofilin inhibition by F-actin depolymerization, migration by scratch wound assay, tumor necrosis factor (TNF-α) by enzyme-linked immunosorbent assay (ELISA), protease-activated receptor-1 (PAR-1) by immunocytochemistry and Western blotting (WB), and protein expression levels of several proteins by WB. SK-1-32 increased neuronal/microglial survival, reduced NO, and prevented neurotoxicity. However, SZ-3 showed no effect on neuronal/microglial survival but prevented microglia from LPS-induced inflammation by decreasing NO and preventing neurotoxicity. Therefore, we selected SZ-3 for further molecular studies, as it showed potent anti-inflammatory activities. SZ-3 decreased cofilin severing activity, and its treatment of LPS-activated HMC-3 cells attenuated microglial activation and suppressed migration and proliferation. HMC-3 cells subjected to thrombin, as an in vitro model for hemorrhagic stroke, and treated with SZ-3 after 3 h showed significantly decreased NO and TNF-α, significantly increased protein expression of phosphocofilin, and decreased PAR-1. In addition, SZ-3-treated SHSY-5Y showed a significant increase in cell viability by significantly reducing nuclear factor-κ B (NF-κB), caspase-3, and high-temperature requirement (HtrA2). Together, our results support the novel idea of targeting cofilin to counter neuroinflammation during secondary injury following ICH.

A multimodal electrochemical approach to measure the effect of zinc on vesicular content and exocytosis in a single cell model of ischemia

Zinc ion is essential for normal brain function that modulates synaptic activity and neuronal plasticity and it is associated with memory formation. Zinc is considered to be a contributing factor to the pathogenesis of ischemia, but the association between zinc and ischemia on vesicular exocytosis is unclear. In this study, we used a combination of chemical analysis methods and a cell model of ischemia/reperfusion to investigate exocytotic release and vesicular content, as well as the effect of zinc alteration on vesicular exocytosis. Oxygen–glucose deprivation and reperfusion (OGDR) was used as an in vitro model of ischemia in a model cell line. Exocytotic release and vesicular storage of catecholamine content were increased following OGDR, resulting in a higher fraction of release during exocytosis. However, zinc eliminated these increases following OGDR and the fraction of release remained unchanged. Understanding the consequences of zinc accumulation on vesicular exocytosis at the early stage of OGDR should aid in the development of therapeutic strategies to reduce ischemic brain injury. As the fraction released has been suggested to be related to presynaptic plasticity, insights are gained towards deciphering ischemia related memory impairment.

Cofilin and Actin Dynamics: Multiple Modes of Regulation and Their Impacts in Neuronal Development and Degeneration

Proteins of the actin depolymerizing factor (ADF)/cofilin family are ubiquitous among eukaryotes and are essential regulators of actin dynamics and function. Mammalian neurons express cofilin-1 as the major isoform, but ADF and cofilin-2 are also expressed. All isoforms bind preferentially and cooperatively along ADP-subunits in F-actin, affecting the filament helical rotation, and when either alone or when enhanced by other proteins, promotes filament severing and subunit turnover. Although self-regulating cofilin-mediated actin dynamics can drive motility without post-translational regulation, cells utilize many mechanisms to locally control cofilin, including cooperation/competition with other proteins. Newly identified post-translational modifications function with or are independent from the well-established phosphorylation of serine 3 and provide unexplored avenues for isoform specific regulation. Cofilin modulates actin transport and function in the nucleus as well as actin organization associated with mitochondrial fission and mitophagy. Under neuronal stress conditions, cofilin-saturated F-actin fragments can undergo oxidative cross-linking and bundle together to form cofilin-actin rods. Rods form in abundance within neurons around brain ischemic lesions and can be rapidly induced in neurites of most hippocampal and cortical neurons through energy depletion or glutamate-induced excitotoxicity. In ~20% of rodent hippocampal neurons, rods form more slowly in a receptor-mediated process triggered by factors intimately connected to disease-related dementias, e.g., amyloid-β in Alzheimer’s disease. This rod-inducing pathway requires a cellular prion protein, NADPH oxidase, and G-protein coupled receptors, e.g., CXCR4 and CCR5. Here, we will review many aspects of cofilin regulation and its contribution to synaptic loss and pathology of neurodegenerative diseases.

Oxygen-glucose deprivation in neurons: implications for cell transplantation therapies

Cell replacement therapies hold the potential to restore neuronal networks compromised by neurodegenerative diseases (such as Parkinson's disease or Huntington's disease), or focal tissue damage (via a stroke or spinal cord injury). Despite some promising results achieved to date, transplanted cells typically exhibit poor survival in the central nervous system, thus limiting therapeutic efficacy of the graft. Although cell death post-transplantation is likely to be multifactorial in causality, growing evidence suggests that the lack of vascularisation at the graft site, and the resulting ischemic host environment, may play a fundamental role in the fate of grafted cells. Herein, we summarise data showing how the deprivation of either oxygen, glucose, or both in combination, impacts the survival of neurons and review strategies which may improve graft survival in the central nervous system.

Prediction of Neurological Recovery After Cardiac Arrest Using Neurofilament Light Chain is Improved by a Proteomics-Based Multimarker Panel

BACKGROUND

Continuous advances in resuscitation care have increased survival, but the rate of favorable neurological outcome remains low. We have shown the usefulness of proteomics in identifying novel biomarkers to predict neurological outcome. Neurofilament light chain (NfL), a marker of axonal damage, has since emerged as a promising single marker. The aim of this study was to assess the predictive value of NfL in comparison with and in addition to our established model.

METHODS

NfL was measured in plasma samples drawn at 48 h after cardiac arrest using single-molecule assays. Neurological function was recorded on the cerebral performance category (CPC) scale at discharge from the intensive care unit and after 6 months. The ability to predict a dichotomized outcome (CPC 1-2 vs. 3-5) was assessed with receiver operating characteristic (ROC) curves.

RESULTS

Seventy patients were included in this analysis, of whom 21 (30%) showed a favorable outcome (CPC 1-2), compared with 49 (70%) with an unfavorable outcome (CPC 3-5) at discharge. NfL increased from CPC 1 to 5 (16.5 pg/ml to 641 pg/ml, p < 0.001). The addition of NfL to the existing model improved it significantly (Wald test, p < 0.001), and the combination of NfL with a multimarker model showed high areas under the ROC curve (89.7% [95% confidence interval 81.7-97.7] at discharge and 93.7% [88.2-99.2] at 6 months) that were significantly greater than each model alone.

CONCLUSIONS

The combination of NfL with other plasma and clinical markers is superior to that of either model alone and achieves high areas under the ROC curve in this relatively small sample.

Propofol Attenuates Inflammatory Damage via Inhibiting NLRP1-Casp1-Casp6 Signaling in Ischemic Brain Injury

Stroke is a common cerebrovascular disease. Inflammation-induced neuronal death is one of the key factors in stroke pathology. Propofol has been shown to ameliorate neuroinflammatory injury, but the exact mechanism of its neuroprotective role remains to be fully elucidated. In the present study, we found that inflammation was activated in ischemic cortical neurons, and the expression of nucleotide-binding domain, leucine-rich-repeat containing family, pyrin domain-containing 1 (NLRP1), NLRP3 inflammasome and effectors in primary cortical neurons increased. However, we found that propofol could inhibit the increased expression of NLRP1 and NLRP3 inflammasome induced by oxygen-glucose deprivation (OGD). Furthermore, the effector molecule caspase-1 (casp1) was revealed to be the downstream target of NLRP1 and propofol repressed the activation of caspase-1 via inhibiting NLRP1 in cortical neurons. Moreover, propofol inhibits caspase-6 activation in neurons through the NLRP1-caspase-1 pathway. Once the expression of caspase6 increases, propofol reduced its neuroprotective effect in OGD-treated cortical neurons. In the stroke middle cerebral artery occlusion (MCAO) model, infusion of caspase-6 inhibitors enhanced the protective effect of propofol on infarct size and neurological function. In conclusion, our results suggest that propofol plays a neuroprotective role in stroke by inhibiting the inflammatory pathway of NLRP1-caspase-1-caspase-6. Overall, these data suggest that propofol plays a key role in the inflammatory-dependent pathway after stroke, providing an important evidence for propofol as an effective strategy for neuroprotection in stroke.

Electroacupuncture Attenuates Ischemic Brain Injury and Cellular Apoptosis via Mitochondrial Translocation of Cofilin

OBJECTIVE

To investigate the potential mechanisms of electroacupuncture (EA) to prevent ischemic stroke.

METHODS

The method of middle cerebral artery occlusion (MCAO) was employed to establish a rat model of ischemic stroke. Seventy-eight Sprague-Dawley rats were divided into the sham group, MCAO + EA control (EC) group, and MCAO + EA (EA) group according to a random number table (n=26 per group). EA was applied to the acupoints of Baihui (DU 20) and Shenting (DU 24) 5 min and 6 h, respectively after the onset of MCAO. Rats in the sham and EC groups received only light isoflurane anesthesia for 30 min after MCAO. The neuroprotective effects of EA were evaluated by rota-rod test, neurological deficit scores and infarct volumes. Additionally, Nissl staining and immunostaining were performed to examine brain damage, rod formation, cellular apoptosis, and neuronal loss induced by ischemia. The activities of caspase-3, and expression levels of cofilin and p-cofilin in mitochondria and cytoplasm after ischemic injury were determined by Western blot.

RESULTS

Compared with the EC group, EA significantly improved neuromotor function and cognitive ability after ischemic stroke (P<0.05 or P<0.01). Therapeutic use of EA also resulted in a significant decrease of cofilin rod formation and microtubule-associated protein-2 (MAP2) degradation in the cortical penumbra area compared with the EC rats (P<0.01). Furthermore, Western blot analysis showed that EA stimulation significantly inhibited mitochondrial translocation of cofilin and caspase-3 cleavage (P<0.05 or P<0.01). Additionally, brain damage (infarct volume and neuropathy), cellular apoptosis and neuronal loss induced by ischemia were remarkably suppressed by EA in the cortical penumbra of rats (P<0.05 or P<0.01).

CONCLUSION

EA treatment after ischemic stroke may attenuate ischemic brain injury and cellular apoptosis through the regulation of mitochondrial translocation of cofilin, a novel mechanism of EA therapy.

Cerebral Ischemia-Reperfusion Is Associated With Upregulation of Cofilin-1 in the Motor Cortex

Cerebral ischemia is one of the leading causes of death. Reperfusion is a critical stage after thrombolysis or thrombectomy, accompanied by oxidative stress, excitotoxicity, neuroinflammation, and defects in synapse structure. The process is closely related to the dephosphorylation of actin-binding proteins (e.g., cofilin-1) by specific phosphatases. Although studies of the molecular mechanisms of the actin cytoskeleton have been ongoing for decades, limited studies have directly investigated reperfusion-induced reorganization of actin-binding protein, and little is known about the gene expression of actin-binding proteins. The exact mechanism is still uncertain. The motor cortex is very important to save nerve function; therefore, we chose the penumbra to study the relationship between cerebral ischemia-reperfusion and actin-binding protein. After transient middle cerebral artery occlusion (MCAO) and reperfusion, we confirmed reperfusion and motor function deficit by cerebral blood flow and gait analysis. PCR was used to screen the high expression mRNAs in penumbra of the motor cortex. The high expression of cofilin in this region was confirmed by immunohistochemistry (IHC) and Western blot (WB). The change in cofilin-1 expression appears at the same time as gait imbalance, especially maximum variation and left front swing. It is suggested that cofilin-1 may partially affect motor cortex function. This result provides a potential mechanism for understanding cerebral ischemia-reperfusion.

LIM kinase inhibitor T56-LIMKi protects mouse brain from photothrombotic stroke

Primary Objective: In an ischemic stroke, the damage spreads from the infarction core to surrounding tissues. The present work was aimed at the search of effective neuroprotectors that restrict injury propagation. Research Design: We studied possible protective effects of inhibitors of protein kinases LIMK2 (T56-LIMKi), DYRK1A (harmine), and tryptophan hydroxylase (4-chlorophenylalanine) on infarction size and morphology of peri-infarct area after photothrombotic stroke (a model of ischemic stroke) in mouse brain. Methods and Procedures: Photothrombotic stroke was induced by laser irradiation of mouse cortex after administration of photosensitizer Bengal Rose, which does not penetrate cells and remains in blood vessels. Under light exposure, it induces vessel occlusion. Infarct volume and histological changes in the cerebral cortex were evaluated 3, 7 and 14 days after photothrombotic impact. Main Outcomes and Results: Harmine and 4-chlorophenylalanine did not influence infarct volume and morphology of peri-infarct area in the mouse brain cortex after photothrombotic stroke. However, LIMK2 inhibitor T56-LIMKi significantly reduced infarct volume 7 and 14 days after photothrombotic stroke. It also increased the percent of normochromic neurons and decreased the fraction of altered cortical cells (hypochromic, hyperchromic and pyknotic neurons). Conclusions: T56-LIMK2i may be considered as a promising anti-stroke agent.

The Role of ADF/Cofilin in Synaptic Physiology and Alzheimer's Disease

Actin-depolymerization factor (ADF)/cofilin, a family of actin-binding proteins, are critical for the regulation of actin reorganization in response to various signals. Accumulating evidence indicates that ADF/cofilin also play important roles in neuronal structure and function, including long-term potentiation and depression. These are the most extensively studied forms of long-lasting synaptic plasticity and are widely regarded as cellular mechanisms underlying learning and memory. ADF/cofilin regulate synaptic function through their effects on dendritic spines and the trafficking of glutamate receptors, the principal mediator of excitatory synaptic transmission in vertebrates. Regulation of ADF/cofilin involves various signaling pathways converging on LIM domain kinases and slingshot phosphatases, which phosphorylate/inactivate and dephosphorylate/activate ADF/cofilin, respectively. Actin-depolymerization factor/cofilin activity is also regulated by other actin-binding proteins, activity-dependent subcellular distribution and protein translation. Abnormalities in ADF/cofilin have been associated with several neurodegenerative disorders such as Alzheimer’s disease. Therefore, investigating the roles of ADF/cofilin in the brain is not only important for understanding the fundamental processes governing neuronal structure and function, but also may provide potential therapeutic strategies to treat brain disorders.

Proteomics-Enriched Prediction Model for Poor Neurologic Outcome in Cardiac Arrest Survivors

OBJECTIVES

Neurologic outcome prediction in out-of-hospital cardiac arrest survivors is highly limited due to the lack of consistent predictors of clinically relevant brain damage. The present study aimed to identify novel biomarkers of neurologic recovery to improve early prediction of neurologic outcome.

DESIGN

Prospective, single-center study, SETTING:: University-affiliated tertiary care center.

PATIENTS

We prospectively enrolled 96 out-of-hospital cardiac arrest survivors into our study.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Neurologic outcome was assessed by the Cerebral Performance Categories score. To identify plasma biomarkers for poor neurologic outcome (Cerebral Performance Categories score ≥ 3), we performed a three-step proteomics strategy of preselection by shotgun analyses, crosschecking in brain tissue samples, and verification by targeted proteomic analyses using a multistep statistical modeling approach. Sixty-three patients (66%) had a poor neurologic outcome. Out of a total of 299 proteins, we identified α-enolase, 14-3-3 protein ζ/δ, cofilin-1, and heat shock cognate 71 kDa protein as novel biomarkers for poor neurologic outcome. The implementation of these biomarkers into a clinical multimarker model, consisting of previously identified covariates associated to outcome, resulted in a significant improvement of neurologic outcome prediction (C-index, 0.70; explained variation, 11.9%; p for added value, 0.019).

CONCLUSIONS

This study identified four novel biomarkers for the prediction of poor neurologic outcome in out-of-hospital cardiac arrest survivors. The implementation of α-enolase, 14-3-3 protein ζ/δ, cofilin-1, and heat shock cognate 71 kDa protein into a multimarker predictive model along with previously identified risk factors significantly improved neurologic outcome prediction. Each of the proteomically identified biomarkers did not only outperform current risk stratification models but may also reflect important pathophysiologic pathways undergoing during cerebral ischemia.

Cofilin Inhibition by Limk1 Reduces Rod Formation and Cell Apoptosis after Ischemic Stroke

Cofilin, a cytoskeletal actin severing protein, is essential for the initiation phase of apoptosis. The formation of cofilin rods (containing 1:1 cofilin:actin) has been studied in cultured mammalian neurons under conditions of excessive glutamate, ATP depletion (ATP-D) or oxidative stress. These conditions simulate the pathologies occurring during ischemic stroke. In this study, we investigated the potential involvement of cofilin during ischemic-stroke induced apoptosis. Transient middle cerebral artery occlusion (tMCAO) was performed to establish an experimental model of ischemic stroke. We used 2,3,5-Triphenyltetrazolium Chloride (TTC) and immunostaining of the neuronal marker neuronal nuclei (NeuN) to evaluate the evolving phases of infarction in rats subjected tMCAO. Immunostaining and TdT-mediated dUTP Nick-End Labeling (TUNEL) apoptosis staining were collaboratively used to examine cofilin rod formation and cell apoptosis in response to ischemia at different time points (2 h, 8 h, 24 h and 7 d). Our results showed that infarct volume increased initially, between the first 2 h to 24 h and became stabilized 24 h to 7 d after tMCAO. The formation of cofilin rods significantly increased in the cortical core (from 2 h) and penumbra (from 8 h), peaking at 24 h and gradually diminishing 7 d after tMCAO. Progressive accumulation of cofilin rods subsequently induced microtubule-associated protein-2 (MAP2) degradation and ischemic cell apoptosis in the infarct cortex after stroke. To further corroborate the role of activated cofilin in ischemic stroke, inhibition of cofilin by LIM kinase (Limk1) over-expression was performed. Lmik1 reduced cofilin rod formation and MAP2 degradation, and consequently, attenuated cofilin mediated-apoptosis 24 h after tMCAO. From this evidence we conclude that cofilin plays a role in the onset of ischemic-induced apoptosis and may be efficacious in future studies as a drug target for ischemic stroke.

5-HT1AR alleviates Aβ-induced cognitive decline and neuroinflammation through crosstalk with NF-κB pathway in mice

The 5-hydroxytryptamine (5-HT) receptor is significant for the regulation of mood and memory. However, the role of 5-HT1AR in β-Amyloid protein (Aβ)-induced cognitive decline, neuroinflammation and the possible mechanism remains elusive. Thus, we aimed to evaluate the effects of 5-HT1AR on Aβ-induced learning and memory decline and neuroinflammation in mice. Novel object recognition and Morris water maze tests were performed to observe learning and memory behavior in mice. Protein levels of Iba1, GFAP, MAP2, TNF-α, Tβ4, C-fos, IKK-β, IKB-α, NF-κBp65, phospho-NF-κBp65 in the hippocampus were examined by immunostaining or western blotting. Aβ1-42-treatment inducing learning and memory decline was shown in novel object recognition and Morris water maze tests; neuroinflammation shown in immunostaining. Our study found out that 5-HT1AR inhibitor WAY100635 showed significant improvement in Aβ-induced learning and memory decline. Moreover, WAY100635 decreases levels of Iba1, GFAP, and TNF-α in the hippocampus, which were related to neuroinflammation. While treatment with 5-HT1AR agonist 8-OH-DPAT or ERK inhibitor U0126 exerted no effects or even aggravated Aβ-induced learning and memory decline. In addition, WAY100635 could downregulate phospho-NF-κB in the hippocampus of Aβ1-42-injected mice. These results provide new insight into the mechanism, for 5-HT1AR in Aβ-induced cognitive impairments through crosstalk with the NF-κB signaling pathway. Our data indicated that WAY100635 was involved in the protective effects against neuroinflammation and improvement of learning and memory in Alzheimer's disease.

Much More Than a Scaffold: Cytoskeletal Proteins in Neurological Disorders

Recent observations related to the structure of the cytoskeleton in neurons and novel cytoskeletal abnormalities involved in the pathophysiology of some neurological diseases are changing our view on the function of the cytoskeletal proteins in the nervous system. These efforts allow a better understanding of the molecular mechanisms underlying neurological diseases and allow us to see beyond our current knowledge for the development of new treatments. The neuronal cytoskeleton can be described as an organelle formed by the three-dimensional lattice of the three main families of filaments: actin filaments, microtubules, and neurofilaments. This organelle organizes well-defined structures within neurons (cell bodies and axons), which allow their proper development and function through life. Here, we will provide an overview of both the basic and novel concepts related to those cytoskeletal proteins, which are emerging as potential targets in the study of the pathophysiological mechanisms underlying neurological disorders.

The role of cofilin in age-related neuroinflammation

Aging brain becomes susceptible to neurodegenerative diseases due to the shifting of microglia and astrocyte phenotypes to an active “pro-inflammatory” state, causing chronic low-grade neuroinflammation. Despite the fact that the role of neuroinflammation during aging has been extensively studied in recent years, the underlying causes remain unclear. The identification of relevant proteins and understanding their potential roles in neuroinflammation can help explain their potential of becoming biomarkers in the aging brain and as drug targets for prevention and treatment. This will eventually reduce the chances of developing neurodegenerative diseases and promote healthier lives in the elderly. In this review, we have summarized the morphological and cellular changes in the aging brain, the effects of age-related neuroinflammation, and the potential role of cofilin-1 during neuroinflammation. We also discuss other factors contributing to brain aging and neuroinflammation.

Cofilin-actin rod formation in experimental stroke is attenuated by therapeutic hypothermia and overexpression of the inducible 70 kD inducible heat shock protein (Hsp70)

BACKGROUND AND PURPOSE

Cofilin-actin rods are covalently linked aggregates of cofilin-1 and actin. Under ischemic conditions, these rods have been observed in neuronal dendrites and axons and may contribute to the loss of these processes. Hypothermia (Hypo) and the 70 kD inducible heat shock protein (Hsp70) are both known to improve outcomes after stroke, but the mechanisms are uncertain. Here, we evaluated the effect of these factors on cofilin-actin rod formation in a mouse model of stroke.

MATERIALS AND METHODS

Mice were subjected to distal middle cerebral artery occlusion (dMCAO) and treated with Hypo using a paradigm previously shown to be neuroprotective. We similarly studied mice that overexpressed transgenic (Tg) or were deficient knockout (Ko) in the inducible 70 kDa heat shock protein (Hsp70), also previously shown to be protective by our group and others. Cofilin-actin rod formation was assessed by histological analysis at 4 and 24 h after dMCAO. Its expression was analyzed in three different regions, namely, infarct core (the center of the infarct), middle cerebral artery (MCA) borderzone (the edge of the brain regions supplied by the MCA), and the ischemic borderzone (border of ischemic lesion). Ischemic lesion size and neurological deficits were also assessed.

RESULTS

Both Hypo-treated and Hsp70 Tg mice had smaller lesion sizes and improved neurological outcomes, whereas Hsp70 Ko mice had larger lesion sizes and worsened neurological outcomes. Cofilin-actin rods were increased after stroke, but were reduced by therapeutic Hypo and in Hsp70 Tg mice. In contrast, cofilin-actin rods were increased in ischemic brains of Hsp70 Ko mice.

CONCLUSIONS

Cofilin-actin rod formation was suppressed under the conditions of neuroprotection and increased under circumstances where outcome was worsened. This suggests that cofilin-actin rods may act to participate in or exacerbate ischemic pathology and warrants further study as a potential therapeutic target.

IL-10 produces a dual effect on OGD-induced neuronal apoptosis of cultured cortical neurons via the NF-κB pathway

As a classic immunoregulatory cytokine, interleukin-10 (IL-10) can provide in vivo and in vitro neuroprotection respectively during cerebral ischemia and after the oxygen-glucose deprivation (OGD)-induced injury. However, its role in cortical neuronal survival at different post-ischemic phases remains unclear. The current study found that IL-10 had distinct effects on the neuronal apoptosis at different OGD stages: at an early stage after OGD, IL-10 promoted the OGD-induced neuronal apoptosis in the cultured primary cortical neurons by activating p65 subunit, which up-regulated Bax expression and down-regulated Bcl-xL expression; at a late OGD stage, however, it attenuated the OGD-induced neuronal apoptosis by activating c-Rel, which up-regulated Bcl-xL expression and down-regulated Bax expression. The early-stage pro-apoptosis and late-stage anti-apoptosis were both partly abolished by PDTC, an NF-κB inhibitor, and promoted by PMA, an NF-κB activator. The optimal anti-apoptotic effect appeared when the cultured neurons were treated with IL-10 at 9-24 h after OGD. Taken together, our findings suggest that IL-10 exerts a dual effect on the survival of the cultured neurons by activating the NF-κB pathway at different stages after OGD injury and that PMA treatment at a late stage can facilitate the IL-10-conferred neuroprotection against OGD-induced neuronal injury.

Brain ischemic insult induces cofilin rod formation leading to synaptic dysfunction in neurons

Ischemic stroke not only induces neuron death in the infarct area but also structural and functional damage of the surviving neurons in the surrounding peri-infarct area. In the present study, we first identified cofilin rod, a pathological rod-like aggregation, formed in neurons of in vivo ischemic stroke animal model and induced neuronal impairment. Cofilin rods formed only on the ipsilateral side of the middle cerebral artery occlusion and reperfusion (MCAO-R) rat brain and showed the highest density in peri-infarct area. Our real-time live cell imaging, immunostaining and patch clamp studies showed that cofilin rod formation in neurons led to dendritic mitochondrial transportation failure, as well as impairment of synaptic structure and functions. Overexpression of LIM kinase or activation of its upstream regulator Rho, suppressed ischemia-induced cofilin rod formation and showed protective effect on synaptic function and structure impairment in both cultured neurons and MCAO-R rat model. In summary, our results demonstrate a novel mechanism of ischemic stroke-induced neuron injury in peri-infarct area and provide a potential target for the protection of neuronal structure and function against brain ischemia insult.

Electroacupuncture protects rats from ischemic brain injury via coffilin in mice

BACKGROUND

This study aimed to study the expression level of cofilin after electroacupuncture (EA) pretreatment, using ischemic brain injury model in mice. In addition, infarct volume and neurological functions were measured to understand whether electroacupuncture stimulation could restore the functions of the brain.

METHODS

Total of 36 mice was randomly divided into three groups: sham group, middle cerebral artery occlusion model (MACO), and middle cerebral artery occlusion model pretreated with EA (MACO + EA). Mice were stimulated at "Baihui (G20)" and "Dazhui (G14)" 24 hours before focal cerebral ischemia. Infarct volume and neuronal function of brain tissue were scored among different experimental groups. The expression level of cofilin and phosphocofilin of brain tissue were evaluated by using Western blot analysis. TUNEL assay was performed to determine the degree of cell apoptosis.

RESULTS

Compared with the sham group, the level of cofilin was dramatically reduced in the MACO group. EA pretreatment could reduce the protein level of cofilin, while EA therapy could also upregulate the protein level of phosphocofilin. Improved neuronal function, smaller infarct volume, and reduced neuronal apoptosis were observed among the mice underwent EA before middle artery occlusion.

CONCLUSION

Our results from Western blot analysis and TUNEL assay might suggest that the upregulation of cofilin was concerned with the EA protects rats from ischemic brain injury. Cofilin might be a potential target for developing drugs against brain ischemia.

Mst1: Function and Mechanism in Brain and Myocardial Ischemia Reperfusion Injury

Mammalian STE20-like kinase-1 (Mst1) is a generally expressed apoptosis-promoting kinase and a key bridgebuilder of apoptotic signaling in the etiology of tissue injury. Despite the fact that the biological function of Mst1 and its role in the cell's signalling network have yet to be determined, however, there is a lot of evidence that Mst1 plays an important role in cell death which results from tissue injury. Previous studies have shown that Mst1 is not only a target for some apoptosis- related molecules such as caspase 3 and P53, but also act as an activator of these proteinases to magnify apoptosis signal pathways. This article reviews the role of Mst1 in the signaling pathways which is related with the neuronal cell apoptosis or microglia activation following myocardial and brain injury. Therefore, this work contributes to better understanding of the pathological process of myocardial and brain injury.

Cofilin-actin rod formation in neuronal processes after brain ischemia

Functional impairment after brain ischemia results in part from loss of neuronal spines and dendrites, independent of neuronal death. Cofilin-actin rods are covalently linked aggregates of cofilin-1 and actin that form in neuronal processes (neurites) under conditions of ATP depletion and oxidative stress, and which cause neurite degeneration if not disassembled. ATP depletion and oxidative stress occur with differing severity, duration, and time course in different ischemic conditions. Here we evaluated four mouse models of brain ischemia to define the conditions that drive formation of cofilin-actin rods. Three of the models provide early reperfusion: transient middle cerebral artery occlusion (MCAo), transient bilateral common carotid artery occlusion (CCAo), and cardiac arrest / cardiopulmonary resuscitation (CA/CPR). Early reperfusion restores ATP generating capacity, but also induces oxidative stress. The fourth model, photothrombotic cortical infarction, does not provide reperfusion. Cofilin-actin rods were formed in each of these models, but with differing patterns. Where acute reperfusion occurred, rod formation was maximal within 4 hours after reperfusion. Where infarction occurred, rods continued to form for at least 24 hours after ischemic onset, and extended into the adjacent non-ischemic tissue. Interventions that limit cofilin-actin rod formation may help to preserve integrity of neuronal processes in permanent ischemia.

A Bioactive Resveratrol Trimer from the Stem Bark of the Sri Lankan Endemic Plant Vateria copallifera

A new resveratrol trimer, vateriferol (1), having four cis-oriented methine protons and constituting four contiguous stereocenters, was isolated from the bark extract of Vateria copallifera by bioassay-guided fractionation using a combination of normal, reversed phase, and size exclusion column chromatography. The structure was established based on its spectroscopic data. Vateriferol (1) was evaluated in vitro for its antioxidant capacity, enzyme inhibitory activity, growth inhibitory activity on a number of cancer cell lines, neuroprotective activity, and anti-inflammatory activity. Vateriferol (1) exhibited AChE inhibitory activity (IC₅₀ 8.4 ± 0.2 μM), ORAC activity (2079 ± 0.20 TE/g), and neuroprotective activity at 1.5 μM using PC12 cells deprived of oxygen and glucose and lowered NO levels in lipopolysaccharide-stimulated SIM-A9 microglial cells at 14.7 and 73.6 μM. Vateriferol (1) exhibited weak cytotoxic potency (<50% growth inhibition) against the tested cell lines at 147.2 μM.

Cerebral Hypoperfusion and Other Shared Brain Pathologies in Ischemic Stroke and Alzheimer's Disease

Newly emerged evidence reveals that ischemic stroke and Alzheimer's disease (AD) share pathophysiological changes in brain tissue including hypoperfusion, oxidative stress, immune exhaustion, and inflammation. A mechanistic link between hypoperfusion and amyloid β accumulation can lead to cell damage as well as to motor and cognitive deficits. This review will discuss decreased cerebral perfusion and other related pathophysiological changes common to both ischemic stroke and AD, such as vascular damages, cerebral blood flow alteration, abnormal expression of amyloid β and tau proteins, as well as behavioral and cognitive deficits. Furthermore, this review highlights current treatment options and potential therapeutic targets that warrant further investigation.

Furoxans (Oxadiazole-4 N-oxides) with Attenuated Reactivity are Neuroprotective, Cross the Blood Brain Barrier, and Improve Passive Avoidance Memory

Nitric oxide (NO) mimetics and other agents capable of enhancing NO/cGMP signaling have demonstrated efficacy as potential therapies for Alzheimer's disease. A group of thiol-dependent NO mimetics known as furoxans may be designed to exhibit attenuated reactivity to provide slow onset NO effects. The present study describes the design, synthesis, and evaluation of a furoxan library resulting in the identification of a prototype furoxan, 5a, which was profiled for use in the central nervous system. Furoxan 5a demonstrated negligible reactivity toward generic cellular thiols under physiological conditions. Nonetheless, cGMP-dependent neuroprotection was observed, and 5a (20 mg/kg) reversed cholinergic memory deficits in a mouse model of passive avoidance fear memory. Importantly, 5a can be prepared as a pharmaceutically acceptable salt and is observed in the brain 12 h after oral administration, suggesting potential for daily dosing and excellent metabolic stability. Continued investigation into furoxans as attenuated NO mimetics for the CNS is warranted.

Neuroprotective Effects of Bioactive Compounds and MAPK Pathway Modulation in "Ischemia"-Stressed PC12 Pheochromocytoma Cells

This review surveys the efforts taken to investigate in vitro neuroprotective features of synthetic compounds and cell-released growth factors on PC12 clonal cell line temporarily deprived of oxygen and glucose followed by reoxygenation (OGD/R). These cells have been used previously to mimic some of the properties of in vivo brain ischemia-reperfusion-injury (IRI) and have been instrumental in identifying common mechanisms such as calcium overload, redox potential, lipid peroxidation and MAPKs modulation. In addition, they were useful for establishing the role of certain membrane penetrable cocktails of antioxidants as well as potential growth factors which may act in neuroprotection. Pharmacological mechanisms of neuroprotection addressing modulation of the MAPK cascade and increased redox potential by natural products, drugs and growth factors secreted by stem cells, in either undifferentiated or nerve growth factor-differentiated PC12 cells exposed to ischemic conditions are discussed for future prospects in neuroprotection studies.

Cofilin signaling in hemin-induced microglial activation and inflammation

Intracerebral hemorrhage (ICH) is the most severe form of stroke and is further exacerbated by the secondary injury involving inflammatory response due to the activation of microglia. This secondary injury is partly due to the toxic effects of hemin, an endogenous breakdown product of hemoglobin. Cofilin, an actin depolymerizing factor, controls actin dynamics and has been previously shown to be involved in mediating neuronal cell death in ischemic conditions and during bacterial lipopolysaccharide induced microglial activation. There are limited studies regarding the deleterious effects of extremely high concentrations of hemin released during ICH and its effects on microglia and subsequent cofilin response. Therefore, investigations were conducted to study the effects of hemin on microglial activation induced inflammation and the critical role of cofilin in mediating the response. We observed that hemin treated microglia had a concentration dependent increase in cofilin expression and NO production. There were increased levels of iNOS, TNF-α, HO1, Nrf2, Wfs-1, XBP-1 and spliced XBP-1 observed in response to hemin treatment and the signaling was found to be partly mediated by cofilin. Acute hemin treatment did not evoke Ca²⁺ signaling and long-term treatment of hemin also resulted in the failure of microglial response to acetylcholine-evoked Ca²⁺ signaling. Knockdown of cofilin by siRNA also reduced acetylcholine-evoked Ca²⁺ signaling. These studies demonstrate that cofilin signaling is important in hemin-induced inflammation, oxidative stress, ER stress, microglial migration, and the ability to evoke Ca²⁺ signaling. Therefore, cofilin inhibition could be a potential therapy in brain injuries triggered by hemin toxicity in conditions like ICH.

Cofilin Mediates LPS-Induced Microglial Cell Activation and Associated Neurotoxicity Through Activation of NF-κB and JAK-STAT Pathway

Microglial cells are activated in response to different types of injuries or stress in the CNS. Such activation is necessary to get rid of the injurious agents and restore tissue homeostasis. However, excessive activation of microglial cells is harmful and contributes to secondary injury. Pertinently, microglial cell activity was targeted in many preclinical and clinical studies but such strategy failed in clinical trials. The main reason behind the failed attempts is the complexity of the injury mechanisms which needs either a combination therapy or targeting a process that is involved in multiple pathways. Cofilin is a cytoskeleton-associated protein involved in actin dynamics. In our previous study, we demonstrated the role of cofilin in mediating neuronal apoptosis during OGD conditions. Previous studies on microglia have shown the involvement of cofilin in ROS formation and phagocytosis. However, additional studies are needed to delineate the role of cofilin in microglial cell activation. Therefore, in the current study, we investigated the role of cofilin in LPS-induced microglial cell activation using cofilin siRNA knockdown paradigms. The viability of differentiated PC12 cells was used as a measure of the neurotoxic potential of conditioned medium derived from cofilin siRNA-transfected and LPS-activated microglial cells. Cofilin knockdown significantly inhibited LPS-induced microglial cell activation through NF-κB and JAK-STAT pathways. The release of proinflammatory mediators (NO, TNF-α, iNOS, and COX2) as well as microglial proliferation and migration rates were significantly reduced by cofilin knockdown. Furthermore, differentiated PC12 cells were protected from the neurotoxicity induced by conditioned medium derived from cofilin-transfected and LPS-activated microglial cells. In conclusion, we demonstrated that cofilin is involved in the cascade of microglial cell activation and further validates our previous study on cofilin's role in mediating neuronal apoptosis. Together, our results suggest that cofilin could present a common target in neurons and microglial cells and might prove to be a promising therapy for different brain injury mechanisms including stroke.

Profiling of Signaling Proteins in Penumbra After Focal Photothrombotic Infarct in the Rat Brain Cortex

In ischemic stroke, cell damage propagates from infarct core to surrounding tissue. To reveal proteins involved in neurodegeneration and neuroprotection, we explored the protein profile in penumbra surrounding the photothrombotic infarct core induced in rat cerebral cortex by local laser irradiation after Bengal Rose administration. Using antibody microarrays, we studied changes in expression of 224 signaling proteins 1, 4, or 24 h after photothrombotic infarct compared with untreated contralateral cortex. Changes in protein expression were greatest at 4 h after photothrombotic impact. These included over-expression of proteins initiating, regulating, or executing various apoptosis stages (caspases, SMAC/DIABLO, Bcl-10, phosphatidylserine receptor (PSR), prostate apoptosis response 4 (Par4), E2F1, p75, p38, JNK, p53, growth arrest and DNA damage inducible protein 153 (GADD153), glutamate decarboxylases (GAD65/67), NMDAR2a, c-myc) and antiapoptotic proteins (Bcl-x, p63, MDM2, p21WAF-1, ERK1/2, ERK5, MAP kinase-activated protein kinase-2 (MAKAPK2), PKCα, PKCβ, PKCμ, RAF1, protein phosphatases 1α and MAP kinase phosphatase-1 (MKP-1), neural precursor cell expressed, developmentally down-regulated 8 (NEDD8), estrogen and EGF receptors, calmodulin, CaMKIIα, CaMKIV, amyloid precursor protein (APP), nicastrin). Phospholipase Cγ1, S-100, and S-100β were down-regulated. Bidirectional changes in levels of adhesion and cytoskeleton proteins were related to destruction and/or remodeling of penumbra. Following proteins regulating actin cytoskeleton were over-expressed: cofilin, actopaxin, p120CTN, α-catenin, p35, myosin Va, and pFAK were up-regulated, whereas ezrin, tropomyosin, spectrin (α + β), β_IV-tubulin and polyglutamated β-tubulin, and cytokeratins 7 and 19 were down-regulated. Down-regulation of syntaxin, AP2β/γ, and adaptin β1/2 indicated impairment of vesicular transport and synaptic processes. Down-regulation of cyclin-dependent kinase 6 (Cdk6), cell division cycle 7-related protein kinase (Cdc7 kinase), telomeric repeat-binding factor 1 (Trf1), and topoisomerase-1 showed proliferation suppression. Cytoprotection proteins AOP-1 and chaperons Hsp70 and Hsp90 were down-regulated. These data provide the integral view on penumbra response to photothrombotic infarct. Some of these proteins may be potential targets for antistroke therapy.

The Emerging Roles of the Calcineurin-Nuclear Factor of Activated T-Lymphocytes Pathway in Nervous System Functions and Diseases

The ongoing epidemics of metabolic diseases and increase in the older population have increased the incidences of neurodegenerative diseases. Evidence from murine and cell line models has implicated calcineurin-nuclear factor of activated T-lymphocytes (NFAT) signaling pathway, a Ca²⁺/calmodulin-dependent major proinflammatory pathway, in the pathogenesis of these diseases. Neurotoxins such as amyloid-β, tau protein, and α-synuclein trigger abnormal calcineurin/NFAT signaling activities. Additionally increased activities of endogenous regulators of calcineurin like plasma membrane Ca²⁺-ATPase (PMCA) and regulator of calcineurin 1 (RCAN1) also cause neuronal and glial loss and related functional alterations, in neurodegenerative diseases, psychotic disorders, epilepsy, and traumatic brain and spinal cord injuries. Treatment with calcineurin/NFAT inhibitors induces some degree of neuroprotection and decreased reactive gliosis in the central and peripheral nervous system. In this paper, we summarize and discuss the current understanding of the roles of calcineurin/NFAT signaling in physiology and pathologies of the adult and developing nervous system, with an emphasis on recent reports and cutting-edge findings. Calcineurin/NFAT signaling is known for its critical roles in the developing and adult nervous system. Its role in physiological and pathological processes is still controversial. However, available data suggest that its beneficial and detrimental effects are context-dependent. In view of recent reports calcineurin/NFAT signaling is likely to serve as a potential therapeutic target for neurodegenerative diseases and conditions. This review further highlights the need to characterize better all factors determining the outcome of calcineurin/NFAT signaling in diseases and the downstream targets mediating the beneficial and detrimental effects.

Actin dynamics and cofilin-actin rods in alzheimer disease

Cytoskeletal abnormalities and synaptic loss, typical of both familial and sporadic Alzheimer disease (AD), are induced by diverse stresses such as neuroinflammation, oxidative stress, and energetic stress, each of which may be initiated or enhanced by proinflammatory cytokines or amyloid-β (Aβ) peptides. Extracellular Aβ-containing plaques and intracellular phospho-tau-containing neurofibrillary tangles are postmortem pathologies required to confirm AD and have been the focus of most studies. However, AD brain, but not normal brain, also have increased levels of cytoplasmic rod-shaped bundles of filaments composed of ADF/cofilin-actin in a 1:1 complex (rods). Cofilin, the major ADF/cofilin isoform in mammalian neurons, severs actin filaments at low cofilin/actin ratios and stabilizes filaments at high cofilin/actin ratios. It binds cooperatively to ADP-actin subunits in F-actin. Cofilin is activated by dephosphorylation and may be oxidized in stressed neurons to form disulfide-linked dimers, required for bundling cofilin-actin filaments into stable rods. Rods form within neurites causing synaptic dysfunction by sequestering cofilin, disrupting normal actin dynamics, blocking transport, and exacerbating mitochondrial membrane potential loss. Aβ and proinflammatory cytokines induce rods through a cellular prion protein-dependent activation of NADPH oxidase and production of reactive oxygen species. Here we review recent advances in our understanding of cofilin biochemistry, rod formation, and the development of cognitive deficits. We will then discuss rod formation as a molecular pathway for synapse loss that may be common between all three prominent current AD hypotheses, thus making rods an attractive therapeutic target. © 2016 Wiley Periodicals, Inc.

Cofilin as a Promising Therapeutic Target for Ischemic and Hemorrhagic Stroke

Neurovascular unit (NVU) is considered as a conceptual framework for investigating the mechanisms as well as developing therapeutic targets for ischemic and hemorrhagic stroke. From a molecular perspective, oxidative stress, excitotoxicity, inflammation, and disruption of the blood brain barrier are broad pathophysiological frameworks on the basis on which potential therapeutic candidates for ischemic and hemorrhagic stroke could be discussed. Cofilin is a potent actin-binding protein that severs and depolymerizes actin filaments in order to generate the dynamics of the actin cytoskeleton. Although studies of the molecular mechanisms of cofilin-induced reorganization of the actin cytoskeleton have been ongoing for decades, the multicellular functions of cofilin and its regulation in different molecular pathways are expanding beyond its primary role in actin cytoskeleton. This review focuses on the role of cofilin in oxidative stress, excitotoxicity, inflammation, and disruption of the blood brain barrier in the context of NVU as well as how and why cofilin could be studied further as a potential target for ischemic and hemorrhagic stroke.