Targeting Enolase in Reducing Secondary Damage in Acute Spinal Cord Injury in Rats

Evaluation and clinical significance of serum neurospecific enolase in children with pneumonia: a case-control study

BACKGROUND

Neurospecific Enolase (NSE), a multifunctional protein, is present in various tissues of the body and plays an important role in many disease processes, such as infection, inflammation, tumours, injury, and immunity. In recent years, the application of NSE in respiratory diseases has become increasingly widespread and a research hotspot.

OBJECTIVE

This study aims to explore the relationship between NSE and childhood pneumonia, providing assistance for the diagnosis and assessment of pneumonia.

METHODS

Using prospective research and case-control methods, We selected 129 children with pneumonia hospitalised in Weifang People's Hospital from September 2020 to April 2022 as the case group. Among them were 67 cases of Mycoplasma pneumoniae pneumonia (MP+), 62 cases of non-Mycoplasma pneumoniae pneumonia (MP -), and 21 cases of severe pneumonia. At the same time, 136 children who underwent outpatient health examinations were selected as the control group. The levels of NSE, ESR, CRP in cases group and NSE in control group were measured separately.

RESULT

The NSE levels in the MP + group were 17.86 (14.29-22.54) ng/mL, while those in the MP- group were 17.89 (14.10-21.66) ng/mL, both of which were higher than the control group's NSE levels of 13.26(12.18,14.44) ng/mL (H = 46.92, P = 0.000). There was no statistically significant difference in NSE levels between the MP + and MP - groups (P > 0.05). The NSE level in the severe pneumonia group was 27.38 (13.95-34.06) ng/mL, higher than that in the mild pneumonia group, which was 17.68 (14.27-21.04) ng/mL, (P = 0.024). The AUC values for diagnosing pneumonia are NSE0.714, CRP0.539, and ESR0.535, with NSE having the highest diagnostic value.

CONCLUSION

Serum NSE can serve as an inflammatory indicator for paediatric pneumonia, which has important clinical guidance significance for the diagnosis, condition evaluation, and prognosis of paediatric pneumonia.

Multifunctional roles of γ-enolase in the central nervous system: more than a neuronal marker

Enolase, a multifunctional protein with diverse isoforms, has generally been recognized for its primary roles in glycolysis and gluconeogenesis. The shift in isoform expression from α-enolase to neuron-specific γ-enolase extends beyond its enzymatic role. Enolase is essential for neuronal survival, differentiation, and the maturation of neurons and glial cells in the central nervous system. Neuron-specific γ-enolase is a critical biomarker for neurodegenerative pathologies and neurological conditions, not only indicating disease but also participating in nerve cell formation and neuroprotection and exhibiting neurotrophic-like properties. These properties are precisely regulated by cysteine peptidase cathepsin X and scaffold protein γ1-syntrophin. Our findings suggest that γ-enolase, specifically its C-terminal part, may offer neuroprotective benefits against neurotoxicity seen in Alzheimer's and Parkinson's disease. Furthermore, although the therapeutic potential of γ-enolase seems promising, the effectiveness of enolase inhibitors is under debate. This paper reviews the research on the roles of γ-enolase in the central nervous system, especially in pathophysiological events and the regulation of neurodegenerative diseases.

Regulation of enolase activation to promote neural protection and regeneration in spinal cord injury

Spinal cord injury (SCI) is a debilitating condition characterized by damage to the spinal cord resulting in loss of function, mobility, and sensation with no U.S. Food and Drug Administration-approved cure. Enolase, a multifunctional glycolytic enzyme upregulated after SCI, promotes pro- and anti-inflammatory events and regulates functional recovery in SCI. Enolase is normally expressed in the cytosol, but the expression is upregulated at the cell surface following cellular injury, promoting glial cell activation and signal transduction pathway activation. SCI-induced microglia activation triggers pro-inflammatory mediators at the injury site, activating other immune cells and metabolic events, i.e., Rho-associated kinase, contributing to the neuroinflammation found in SCI. Enolase surface expression also activates cathepsin X, resulting in cleavage of the C-terminal end of neuron-specific enolase (NSE) and non-neuronal enolase (NNE). Fully functional enolase is necessary as NSE/NNE C-terminal proteins activate many neurotrophic processes, i.e., the plasminogen activation system, phosphatidylinositol-4,5-bisphosphate 3-kinase/protein kinase B, and mitogen-activated protein kinase/extracellular signal-regulated kinase. Studies here suggest an enolase inhibitor, ENOblock, attenuates the activation of Rho-associated kinase, which may decrease glial cell activation and promote functional recovery following SCI. Also, ENOblock inhibits cathepsin X, which may help prevent the cleavage of the neurotrophic C-terminal protein allowing full plasminogen activation and phosphatidylinositol-4,5-bisphosphate 3-kinase/mitogen-activated protein kinase activity. The combined NSE/cathepsin X inhibition may serve as a potential therapeutic strategy for preventing neuroinflammation/degeneration and promoting neural cell regeneration and recovery following SCI. The role of cell membrane-expressed enolase and associated metabolic events should be investigated to determine if the same strategies can be applied to other neurodegenerative diseases. Hence, this review discusses the importance of enolase activation and inhibition as a potential therapeutic target following SCI to promote neuronal survival and regeneration.

Transplanting Human Neural Stem Cells with ≈50% Reduction of SOX9 Gene Dosage Promotes Tissue Repair and Functional Recovery from Severe Spinal Cord Injury

Neural stem cells (NSCs) derived from human pluripotent stem cells (hPSCs) are considered a major cell source for reconstructing damaged neural circuitry and enabling axonal regeneration. However, the microenvironment at the site of spinal cord injury (SCI) and inadequate intrinsic factors limit the therapeutic potential of transplanted NSCs. Here, it is shown that half dose of SOX9 in hPSCs-derived NSCs (hNSCs) results in robust neuronal differentiation bias toward motor neuron lineage. The enhanced neurogenic potency is partly attributed to the reduction of glycolysis. These neurogenic and metabolic properties retain after transplantation of hNSCs with reduced SOX9 expression in a contusive SCI rat model without the need for growth factor-enriched matrices. Importantly, the grafts exhibit excellent integration properties, predominantly differentiate into motor neurons, reduce glial scar matrix accumulation to facilitate long-distance axon growth and neuronal connectivity with the host as well as dramatically improve locomotor and somatosensory function in recipient animals. These results demonstrate that hNSCs with half SOX9 gene dosage can overcome extrinsic and intrinsic barriers, representing a powerful therapeutic potential for transplantation treatments for SCI.

The Relationship Between Neuron-Specific Enolase and Clinical Outcomes in Patients Undergoing Mechanical Thrombectomy

Purpose

Neuron-specific enolase (NSE) is considered a biomarker for the severity of nervous system diseases. We sought to explore whether serum NSE concentration in ischemic stroke patients undergoing mechanical thrombectomy (MT) is related to 3-month functional outcome and symptomatic intracranial hemorrhage (sICH).

Patients and Methods

We retrospectively collected the data of acute ischemic stroke patients with anterior circulation infarction receiving MT within 6 h in our stroke center. Favorable outcome and poor outcome at 3 months were defined as modified Rankin Scale (mRS) score 0-2 and 3-6, respectively. sICH was defined according to the Heidelberg bleeding classification. We used multivariate logistic regression model and receiver operating characteristic curves to investigate the correlation between NSE and clinical outcomes.

Results

Among the 426 patients enrolled, 40 (9.4%) patients developed sICH. Three-month favorable outcome in 160 (37.6%) and poor outcome in 266 (62.4%) patients were observed. Serum NSE levels was significantly correlated with 3-month mRS score (R = 0.473, P < 0.001). A cutoff value of 15.29 and 23.12 ng/mL for serum NSE was detected in discriminating 3-month poor outcome (area under the curve, 0.724) and sICH (area under the curve, 0.716), respectively. Multivariate analysis showed that high serum NSE levels were independently associated with 3-month poor outcome (odds ratio [OR] 5.049, 95% confidence interval [CI] 2.933-8.689, P<0.001) and sICH (OR 5.111, 95% CI 2.210-11.820, P < 0.001).

Conclusion

Our study demonstrated that high serum NSE levels after receiving MT were independently associated with 3-month poor outcome and sICH in acute ischemic stroke patients. Serum NSE levels could be a good predictor of clinical outcomes for patients receiving MT.

Exosomes derived from bone marrow mesenchymal stem cells protect the injured spinal cord by inhibiting pericyte pyroptosis

Mesenchymal stem cell (MSC) transplantation is a promising treatment strategy for spinal cord injury, but immunological rejection and possible tumor formation limit its application. The therapeutic effects of MSCs mainly depend on their release of soluble paracrine factors. Exosomes are essential for the secretion of these paracrine effectors. Bone marrow mesenchymal stem cell-derived exosomes (BMSC-EXOs) can be substituted for BMSCs in cell transplantation. However, the underlying mechanisms remain unclear. In this study, a rat model of T10 spinal cord injury was established using the impact method. Then, 30 minutes and 1 day after spinal cord injury, the rats were administered 200 μL exosomes via the tail vein (200 μg/mL; approximately 1 × 10⁶ BMSCs). Treatment with BMSC-EXOs greatly reduced neuronal cell death, improved myelin arrangement and reduced myelin loss, increased pericyte/endothelial cell coverage on the vascular wall, decreased blood-spinal cord barrier leakage, reduced caspase 1 expression, inhibited interleukin-1β release, and accelerated locomotor functional recovery in rats with spinal cord injury. In the cell culture experiment, pericytes were treated with interferon-γ and tumor necrosis factor-α. Then, Lipofectamine 3000 was used to deliver lipopolysaccharide into the cells, and the cells were co-incubated with adenosine triphosphate to simulate injury in vitro. Pre-treatment with BMSC-EXOs for 8 hours greatly reduced pericyte pyroptosis and increased pericyte survival rate. These findings suggest that BMSC-EXOs may protect pericytes by inhibiting pyroptosis and by improving blood-spinal cord barrier integrity, thereby promoting the survival of neurons and the extension of nerve fibers, and ultimately improving motor function in rats with spinal cord injury. All protocols were conducted with the approval of the Animal Ethics Committee of Zhengzhou University on March 16, 2019.

Implications of enolase in the RANKL-mediated osteoclast activity following spinal cord injury

Spinal Cord Injury (SCI) is a debilitating condition characterized by damage to the spinal cord, resulting in loss of function, mobility, and sensation. Although increasingly prevalent in the US, no FDA-approved therapy exists due to the unfortunate complexity of the condition, and the difficulties of SCI may be furthered by the development of SCI-related complications, such as osteoporosis. SCI demonstrates two crucial stages for consideration: the primary stage and the secondary stage. While the primary stage is suggested to be immediate and irreversible, the secondary stage is proposed as a promising window of opportunity for therapeutic intervention. Enolase, a metabolic enzyme upregulated after SCI, performs non-glycolytic functions, promoting inflammatory events via extracellular degradative actions and increased production of inflammatory cytokines and chemokines. Neuron-specific enolase (NSE) serves as a biomarker of functional damage to neurons following SCI, and the inhibition of NSE has been demonstrated to reduce signs of secondary injury of SCI and to ameliorate dysfunction. This Viewpoint article involves enolase activation in the regulation of RANK-RANKL pathway and summarizes succinctly the mechanisms influencing osteoclast-mediated resorption of bone in SCI. Our laboratory proposes that inhibition of enolase activation may reduce SCI-induced inflammatory response and decrease osteoclast activity, limiting the chances of skeletal tissue loss in SCI.

Protective Effects of Estrogen via Nanoparticle Delivery to Attenuate Myelin Loss and Neuronal Death after Spinal Cord Injury

Spinal cord injury (SCI) is associated with devastating neurological deficits affecting more than 11,000 Americans each year. Although several therapeutic agents have been proposed and tested, no FDA-approved pharmacotherapy is available for SCI treatment. We have recently demonstrated that estrogen (E2) acts as an antioxidant and anti-inflammatory agent, attenuating gliosis in SCI. We have also demonstrated that nanoparticle-mediated focal delivery of E2 to the injured spinal cord decreases lesion size, reactive gliosis, and glial scar formation. The current study tested in vitro effects of E2 on reactive oxygen species (ROS) and calpain activity in microglia, astroglia, macrophages, and fibroblasts, which are believed to participate in the inflammatory events and glial scar formation after SCI. E2 treatment decreased ROS production and calpain activity in these glial cells, macrophages, and fibroblast cells in vitro. This study also tested the efficacy of fast- and slow-release nanoparticle-E2 constructs in a rat model of SCI. Focal delivery of E2 via nanoparticles increased tissue distribution of E2 over time, attenuated cell death, and improved myelin preservation in injured spinal cord. Specifically, the fast-release nanoparticle-E2 construct reduced the Bax/Bcl-2 ratio in injured spinal cord tissues, and the slow-release nanoparticle-E2 construct prevented gliosis and penumbral demyelination distal to the lesion site. These data suggest this novel E2 delivery strategy to the lesion site may decrease inflammation and improve functional outcomes following SCI.

Alpha-Enolase: Emerging Tumor-Associated Antigen, Cancer Biomarker, and Oncotherapeutic Target

Alpha-enolase, also known as enolase-1 (ENO1), is a glycolytic enzyme that “moonlights” as a plasminogen receptor in the cell surface, particularly in tumors, contributing to cancer cell proliferation, migration, invasion, and metastasis. ENO1 also promotes other oncogenic events, including protein-protein interactions that regulate glycolysis, activation of signaling pathways, and resistance to chemotherapy. ENO1 overexpression has been established in a broad range of human cancers and is often associated with poor prognosis. This increased expression is usually accompanied by the generation of anti-ENO1 autoantibodies in some cancer patients, making this protein a tumor associated antigen. These autoantibodies are common in patients with cancer associated retinopathy, where they exert pathogenic effects, and may be triggered by immunodominant peptides within the ENO1 sequence or by posttranslational modifications. ENO1 overexpression in multiple cancer types, localization in the tumor cell surface, and demonstrated targetability make this protein a promising cancer biomarker and therapeutic target. This mini-review summarizes our current knowledge of ENO1 functions in cancer and its growing potential as a cancer biomarker and guide for the development of novel anti-tumor treatments.

A New Therapeutic Strategy Targeting Protein Deacetylation for Spinal Cord Injury

Lysine acetylation is a post-translational modification that regulates a diversity of biological processes. However, its implication in spinal cord injury (SCI) remains unclear. Here we investigated the acetylation events in injured spinal cords on a proteomic scale for the first time. Additionally, whether promoting acetylation could mitigate SCI was evaluated. A total of 268 differentially acetylated peptides were identified. Among them, 2 peptides were up-acetylated and 141 peptides were down-acetylated in the injured spinal cord tissues (Fold change >2 and P < 0.05). There were also 116 unique acetylated peptides in the sham group and 9 unique acetylated peptides in the SCI group. Functional enrichment analysis revealed that differently acetylated proteins were involved in multiple cellular processes and metabolic processes. Kyoto Encyclopaedia of Genes and Genomes analysis showed that several pathways, including cGMP-PKG signaling pathway and hypoxia-inducible factor-1 (HIF-1) signaling pathway, were predominantly presented. Moreover, promoting acetylation using glycerol triacetate (GTA) showed a therapeutic effect on SCI, with improved Basso-Beattie-Bresnahan scores and histologic morphology, and decreased neuronal apoptosis and inflammation. In conclusion, our data indicated that protein deacetylation might play crucial roles in the development of secondary injury of SCI, and promoting acetylation by GTA effectively mitigated SCI. Our data not only enhance our understanding on acetylproteome dataset in the spinal cord tissues, but also provide novel insights for the treatment of SCI.

Phosphoglycerate Mutase 1 Prevents Neuronal Death from Ischemic Damage by Reducing Neuroinflammation in the Rabbit Spinal Cord

Phosphoglycerate mutase 1 (PGAM1) is a glycolytic enzyme that increases glycolytic flux in the brain. In the present study, we examined the effects of PGAM1 in conditions of oxidative stress and ischemic damage in motor neuron-like (NSC34) cells and the rabbit spinal cord. A Tat-PGAM1 fusion protein was prepared to allow easy crossing of the blood-brain barrier, and Control-PGAM1 was synthesized without the Tat peptide protein transduction domain. Intracellular delivery of Tat-PGAM1, not Control-PGAM1, was achieved in a time- and concentration-dependent manner. Immunofluorescent staining confirmed the intracellular expression of Tat-PGAM1 in NSC34 cells. Tat-PGAM1, but not Control-PGAM1, significantly alleviated H₂O₂-induced oxidative stress, neuronal death, mitogen-activated protein kinase, and apoptosis-inducing factor expression in NSC34 cells. After ischemia induction in the spinal cord, Tat-PGAM1 treatment significantly improved ischemia-induced neurological impairments and ameliorated neuronal cell death in the ventral horn of the spinal cord 72 h after ischemia. Tat-PGAM1 treatment significantly mitigated the ischemia-induced increase in malondialdehyde and 8-iso-prostaglandin F2α production in the spinal cord. In addition, Tat-PGAM1, but not Control-PGAM1, significantly decreased microglial activation and secretion of pro-inflammatory cytokines, such as interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α induced by ischemia in the ventral horn of the spinal cord. These results suggest that Tat-PGAM1 can be used as a therapeutic agent to reduce spinal cord ischemia-induced neuronal damage by lowering the oxidative stress, microglial activation, and secretion of pro-inflammatory cytokines, such as IL-1β, IL-6, and TNF-α.

Multifunctional neuron-specific enolase: its role in lung diseases

Neuron-specific enolase (NSE), also known as gamma (γ) enolase or enolase-2 (Eno2), is a form of glycolytic enolase isozyme and is considered a multifunctional protein. NSE is mainly expressed in the cytoplasm of neurons and neuroendocrine cells, especially in those of the amine precursor uptake and decarboxylation (APUD) lineage such as pituitary, thyroid, pancreas, intestine and lung. In addition to its well-established glycolysis function in the cytoplasm, changes in cell localization and differential expression of NSE are also associated with several pathologies such as infection, inflammation, autoimmune diseases and cancer. This article mainly discusses the role and diagnostic potential of NSE in some lung diseases.

Calpain mediated expansion of CD4+ cytotoxic T cells in rodent models of Parkinson's disease

Parkinson's disease (PD), a debilitating progressive degenerative movement disorder associated with loss of dopaminergic (DA) neurons in the substantia nigra (SN), afflicts approximately one million people in the U.S., including a significant number of Veterans. Disease characteristics include tremor, rigidity, postural instability, bradykinesia, and at a cellular level, glial cell activation and Lewy body inclusions in DA neurons. The most potent medical/surgical treatments do not ultimately prevent disease progression. Therefore, new therapies must be developed to halt progression of the disease. While the mechanisms of the degenerative process in PD remain elusive, chronic inflammation, a common factor in many neurodegenerative diseases, has been implicated with associated accumulation of toxic aggregated α-synuclein in neurons. Calpain, a calcium-activated cysteine neutral protease, plays a pivotal role in SN and spinal cord degeneration in PD via its role in α-synuclein aggregation, activation/migration of microglia and T cells, and upregulation of inflammatory processes. Here we report an increased expression of a subset of CD4+ T cells in rodent models of PD, including MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) mice and DSP-4 [N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine hydrochloride]/6-hydroxydopamine rats, which produced higher levels of perforin and granzyme B - typically found in cytotoxic T cells. Importantly, the CD4+ cytotoxic subtype was attenuated following calpain inhibition in MPTP mice, suggesting that calpain and this distinct CD4+ T cell subset may have critical roles in the inflammatory process, disease progression, and neurodegeneration in PD.

Enolase inhibition alters metabolic hormones and inflammatory factors to promote neuroprotection in spinal cord injury

Enolase inhibition is a potential therapeutic strategy currently being investigated for treatment of spinal cord injury (SCI) as it reduces pro-inflammatory cytokines and chemokines, alters metabolic factors, and reduces gliosis in acute SCI. Herein, the role of enolase in SCI has been examined to better understand the effects of this enzyme on inflammation, metabolic hormones, glial cell activation, and neuroprotection under these shorter injury conditions. Immunohistochemical analyses of inflammatory markers vimentin, Cox-2, and caspase-1 indicated that enolase inhibition attenuated the elevated levels of inflammation seen following SCI. Iba1, GFAP, NFP, and CSPG staining indicated that enolase inhibition with prolonged administration of ENOblock reduced microglia/astrocyte activation and lead to enhanced neuroprotection in SCI. An analysis of metabolic hormones revealed that ENOblock treatment significantly upregulated plasma concentrations of peptide YY, glucagon-like peptide 1, glucose-dependent insulinotropic peptide, glucagon, and insulin hormones as compared to vehicle-treated controls (Mann-Whitney, p ≤ 0.05). ENOblock did not have a significant effect on plasma concentrations of pancreatic polypeptide. Interestingly, ENOblock treatment inhibited chondroitin sulfate proteoglycan (CSPG), which is produced by activated glia and serves to block regrowth of axons across the lesion site following injury. An increased level of NeuN and MBP with reduced caspase-1 was detected in SCI tissues after ENOblock treatment, suggesting preservation of myelin and induction of neuroprotection. ENOblock also induced improved motor function in SCI rats, indicating a role for enolase in modulating inflammatory and metabolic factors in SCI with important implications for clinical consideration.

S100B and NSE in Cluster Headache - Evidence for Glial Cell Activation?

OBJECTIVE

Neuronal-specific enolase (NSE) and protein S100B have gained considerable interest as the markers of CNS injury, glial cell activation, and/or blood-brain barrier (BBB) disruption. No studies have investigated NSE and S100B in cluster headache (CH), but these biomarkers could contribute to the understanding of CH.

METHODS

Patients with episodic CH in bout (eCHa), in remission (eCHr), and chronic CH (cCH) were included in this randomized, double-blind, placebo-controlled, 2-way cross-over provocation study carried out at the Danish Headache Center. The primary endpoints included (1) differences of NSE and S100B in between groups (eCHa, eCHr, and cCH) at baseline; (2) differences over time in plasma concentrations of NSE and S100B between patient developing an attack and those who did not; (3) differences in plasma concentrations over time of NSE and S100B between active day and placebo day. Baseline findings were compared to the historical data on migraine patients and healthy controls and presented with means ± SD.

RESULTS

Nine eCHa, 9 eCHr, and 13 cCH patients completed the study and blood samples from 11 CGRP-induced CH attacks were obtained. There were no differences in NSE levels between CH groups at baseline, but CH patients in active disease phase had higher levels compared with 32 migraine patients (9.1 ± 2.2 µg/L vs 6.0 ± 2.2 µg/L, P < .0001) and 6 healthy controls (9.1 ± 2.2 µg/L vs 7.3 ± 2.0 µg/L, P = .007). CGRP-infusion caused no NSE changes and, but a slight, non-significant, increase in NSE was seen in patients who reported a CGRP-induced CH attack (2.39 µg/L, 95% Cl [-0.26, 3.85], P = .061). At baseline S100B levels in eCHa patients were higher compared to cCH patients (0.06 ± 0.02 µg/L vs 0.04 ± 0.02 µg/L, P = .018). Infusion of CGRP and CGRP-induced attacks did not change S100B levels. Apart from induced CH-attacks no other adverse events were noted.

CONCLUSIONS

At baseline eCHa patients had higher S100B plasma levels than cCH patients and there was a slight, however not significant, NSE increase in response to CGRP-induced CH attack. Our findings suggest a possible role of an ictal activation of glial cells in CH pathophysiology, but further studies are warranted.

Neuropeptide system parameters in acute herpes zoster

The neuropeptides comprise an important part in the nervous system interacting with endocrine and immune systems. Peptide regulators are responsible for the continuity of communicating elements, which support homeostasis, however, despite abundant research examining neuropeptides, not all specific mechanisms and features of interacting proteins with cells and immune components have been uncovered. Objective: to perform a comprehensive assessment of neuropeptide system in patients with herpes zoster. Materials and methods: 106 in-hospital patients were examined diagnosed with herpes zoster within 2016–2019 period. Control group consisted of 30 healthy age- and sex-matched volunteers. Blood serum was collected after verifying diagnosis on day 1. After discharge, patients were monitored for signs of pain syndrome and overall state within 3 months. It allowed to divide patients into 3 groups retrospectively. Group 1 — patients with herpes zoster, accompanied by mild or moderate pain syndrome; group 2 — patients with herpes zoster, accompanied by severe pain; group 3 — patients with herpes zoster, complicated by postherpetic neuralgia. Level of serum protein s100B, myelin basic protein, nerve growth factor, brain-derived neurotrophic factor, neuron specific enolase was measured by using specific reagents purchased from “RD Diagnostics Inc.” (США). Results. it was found that level of serum protein S100B in all groups was significantly increased compared to control group, showing no inter-group differences. Amount of myelin basic protein in all study groups vs. control was significantly higher. Moreover, level of these parameters in group 2 vs. group 1 and 3 was significantly elevated. In addition, level of nerve growth factor was significantly increased in group 1 vs. groups 2 and 3, whereas in group 3 it was significantly lower than in control and group 2. Brain-derived neurotrophic factor was significantly decreased in all the study groups compared to control, showing no significant intergroup differences. Level of neuron-specific enolase was significantly increased in group 3 vs. control as well as group 1 and 2. The data obtained allowed to identify two parameters for assessing a risk of postherpetic neuralgia in acute herpes zoster, as well as provided deeper insights into the pathogenesis of neuroimmune disorders accompanying herpes zoster.

Protective effect of rhodioloside and bone marrow mesenchymal stem cells infected with HIF-1-expressing adenovirus on acute spinal cord injury

Rhodioloside has been shown to protect cells from hypoxia injury, and bone marrow mesenchymal stem cells have a good effect on tissue repair. To study the effects of rhodioloside and bone marrow mesenchymal stem cells on spinal cord injury, a rat model of spinal cord injury was established using the Infinite Horizons method. After establishing the model, the rats were randomly divided into five groups. Rats in the control group were intragastrically injected with phosphate buffered saline (PBS) (5 μL). PBS was injected at 6 equidistant points around 5 mm from the injury site and at a depth of 5 mm. Rats in the rhodioloside group were intragastrically injected with rhodioloside (5 g/kg) and intramuscularly injected with PBS. Rats in the mesenchymal stem cell (MSC) group were intramuscularly injected with PBS and intramuscularly with MSCs (8 × 10⁶/mL in a 50-μL cell suspension). Rats in the Ad-HIF-MSC group were intragastrically injected with PBS and intramuscularly injected with HIF-1 adenovirus-infected MSCs. Rats in the rhodioloside + Ad-HIF-MSC group were intramuscularly injected with MSCs infected with the HIF-1 adenovirus and intragastrically injected with rhodioloside. One week after treatment, exercise recovery was evaluated with a modified combined behavioral score scale. Hematoxylin-eosin staining and Pischingert’s methylene blue staining were used to detect any histological or pathological changes in spinal cord tissue. Levels of adenovirus IX and Sry mRNA were detected by real-time quantitative polymerase chain reaction and used to determine the number of adenovirus and mesenchymal stem cells that were transfected into the spinal cord. Immunohistochemical staining was applied to detect HIF-1 protein levels in the spinal cord. The results showed that: (1) compared with the other groups, the rhodioloside + Ad-HIF-MSC group exhibited the highest combined behavioral score (P < 0.05), the most recovered tissue, and the greatest number of neurons, as indicated by Pischingert’s methylene blue staining. (2) Compared with the PBS group, HIF-1 protein expression was greater in the rhodioloside group (P < 0.05). (3) Compared with the Ad-HIF-MSC group, Sry mRNA levels were higher in the rhodioloside + Ad-HIF-MSC group (P < 0.05). These results confirm that rhodioloside combined with bone marrow mesenchymal stem cells can promote the recovery of spinal cord injury and activate the HIF-1 pathway to promote the survival of bone marrow mesenchymal stem cells and repair damaged neurons within spinal cord tissue. This experiment was approved by the Animal Ethics Committee of Gansu University of Traditional Chinese Medicine, China (approval No. 2015KYLL029) in June 2015.

Neuroectodermal Stem Cells Grafted into the Injured Spinal Cord Induce Both Axonal Regeneration and Morphological Restoration via Multiple Mechanisms

Spinal cord contusion injury leads to severe loss of gray and white matter and subsequent deficit of motor and sensory functions below the lesion. In this study, we investigated whether application of murine clonal embryonic neuroectodermal stem cells can prevent the spinal cord secondary damage and induce functional recovery. Stem cells (NE-GFP-4C cell line) were grafted intraspinally or intravenously immediately or one week after thoracic spinal cord contusion injury. Control animals received cell culture medium or fibrin intraspinally one week after injury. Functional tests (Basso, Beattie, Bresnahan, CatWalk^®) and detailed morphological analysis were performed to evaluate the effects of grafted cells. Stem cells applied either locally or intravenously induced significantly improved functional recovery compared with their controls. Morphologically, stem cell grafting prevented the formation of secondary injury and promoted sparing of the gray and white matters. The transplanted cells integrated into the host tissue and differentiated into neurons, astrocytes, and oligodendrocytes. In intraspinally grafted animals, the corticospinal tract axons regenerated along the ventral border of the cavity and have grown several millimeters, even beyond the caudal end of the lesion. The extent of regeneration and functional improvement was inversely related to the amounts of chondroitin sulphate and ephrin-B2 molecules around the cavity and to the microglial and astrocytic reactions in the injured segment early after injury. The grafts produced glial cell derived neurotrophic factor, macrophage inflammatory protein-1a, interleukin (IL)-6 and IL-10 in a paracrine fashion for at least one week. Treating the grafted cords with neutralizing antibodies against these four factors through the use of osmotic pumps nearly completely abolished the effect of the graft. The non-significant functional improvement after function blocking is likely because the stem cell derivatives settled in the injured cord. These data suggest that grafted neuroectodermal stem cells are able to prevent the secondary spinal cord damage and induce significant regeneration via multiple mechanisms.

Enolase1 Alleviates Cerebral Ischemia-Induced Neuronal Injury via Its Enzymatic Product Phosphoenolpyruvate

Stroke is a leading cause of disability and the second leading cause of death among adults worldwide, while the mechanisms underlying neuronal death and dysfunction remain poorly understood. Here, we investigated the differential proteomic profiles of mouse brain homogenate with 3 h of middle cerebral artery occlusion (MCAO) ischemia, or sham, using Coomassie Brilliant Blue staining, followed by mass spectrometry. We identified enolase1 (ENO1), a key glycolytic enzyme, as a potential mediator of neuronal injury in MCAO ischemic model. Reverse transcription polymerase chain reaction and western blotting data showed that ENO1 was ubiquitously expressed in various tissues, distinct regions of brain, and different postnatal age. Immunohistochemical analysis revealed that ENO1 is localized in neuronal cytoplasm and dendrites. Interestingly, the expression level of ENO1 was significantly increased in the early stage, but dramatically decreased in the late stage, of cerebral ischemia in vivo. This dynamic change was consistent with our finding in cultured hippocampal neurons treated with oxygen/glucose deprivation (OGD) in vitro. Importantly, ENO1 overexpression in cultured neurons alleviated dendritic and spinal loss caused by OGD treatment. Furthermore, the enzymatic product of ENO1, phosphoenolpyruvate (PEP), was also synchronously changed along with the dynamic ENO1 level. The neuronal injury caused by OGD treatment in vitro or ischemia in vivo was mitigated by the application of PEP. Taken together, our data revealed that ENO1 plays a novel and protective role in cerebral ischemia-induced neuronal injury, highlighting a potential of ENO1 as a therapeutic target of neuronal protection from cerebral ischemia.

ENOblock inhibits the pathology of diet-induced obesity

Obesity is a medical condition that impacts on all levels of society and causes numerous comorbidities, such as diabetes, cardiovascular disease, and cancer. We assessed the suitability of targeting enolase, a glycolysis pathway enzyme with multiple, secondary functions in cells, to treat obesity. Treating adipocytes with ENOblock, a novel modulator of these secondary ‘moonlighting’ functions of enolase, suppressed the adipogenic program and induced mitochondrial uncoupling. Obese animals treated with ENOblock showed a reduction in body weight and increased core body temperature. Metabolic and inflammatory parameters were improved in the liver, adipose tissue and hippocampus. The mechanism of ENOblock was identified as transcriptional repression of master regulators of lipid homeostasis (Srebp-1a and Srebp-1c), gluconeogenesis (Pck-1) and inflammation (Tnf-α and Il-6). ENOblock treatment also reduced body weight gain, lowered cumulative food intake and increased fecal lipid content in mice fed a high fat diet. Our results support the further drug development of ENOblock as a therapeutic for obesity and suggest enolase as a new target for this disorder.

Identification of Proteins Differentially Expressed in the Striatum by Melatonin in a Middle Cerebral Artery Occlusion Rat Model-a Proteomic and in silico Approach

Ischemic stroke is characterized by permanent or transient obstruction of blood flow, which initiates a cascading pathological process, starting from acute ATP loss to subsequent membrane depolarization, glutamate excitotoxicity, and calcium overload. Melatonin is a potent antioxidant that exerts protective effects in different experimental stroke models. In this study, melatonin effects were demonstrated by a proteomic and in silico approach. The proteomic study identified differentially expressed proteins by 2D gel electrophoresis in the striatum 24 h after middle cerebral artery occlusion. Proteomic analysis revealed several proteins with aberrant expression and was validated by western blot and immunofluorescence analysis. Homology modeling was performed to build 3D structures for γ-enolase, thioredoxin (TRX), and heat shock 60 (HSP60) by the template crystal structures using a protein data bank as a sequence database. The structure refinement of each model was achieved by energy minimization via molecular dynamic simulation, and the generated models were further assessed for stability by Procheck and ProSA. The models were processed for docking analysis using AutoDock Vina, and post-docking analysis was determined by discovery studio. The proteomic study showed decreased expression of γ-enolase, TRX, and protein phosphatase 2A subunit B and increased expression of collapsin response mediator protein 2 and HSP60 in the striatum after ischemic injury. Treatment with melatonin modulated the expression profiles of these proteins. This study demonstrated the neuroprotective role of melatonin in the ischemic striatum using a proteomic and in silico approach. Collectively, melatonin may act in a multimechanistic way by modulating the expression of several proteins in the ischemic striatum.

Endoplasmic reticulum stress, autophagic and apoptotic cell death, and immune activation by a natural triterpenoid in human prostate cancer cells

Though the current therapies are effective at clearing an early stage prostate cancer, they often fail to treat late-stage metastatic disease. We aimed to investigate the molecular mechanisms underlying the anticancer effects of a natural triterpenoid, ganoderic acid DM (GA-DM), on two human prostate cancer cell lines: the androgen-independent prostate carcinoma (PC-3), and androgen-sensitive prostate adenocarcinoma (LNCaP). Cell viability assay showed that GA-DM was relatively more toxic to LNCaP cells than to PC-3 cells (IC₅₀ s ranged 45-55 µM for PC-3, and 20-25 µM for LNCaP), which may have occurred due to differential expression of p53. Hoechst DNA staining confirmed detectable nuclear fragmentation in both cell lines irrespective of the p53 status. GA-DM treatment decreased Bcl-2 proteins while it upregulated apoptotic Bax and autophagic Beclin-1, Atg5, and LC-3 molecules, and caused an induction of both early and late events of apoptotic cell death. Biochemical analyses of GA-DM-treated prostate cancer cells demonstrated that caspase-3 cleavage was notable in GA-DM-treated PC-3 cells. Interestingly, GA-DM treatment altered cell cycle progression in the S phase with a significant growth arrest in the G2 checkpoint and enhanced CD4 ⁺ T cell recognition of prostate tumor cells. Mechanistic study of GA-DM-treated prostate cancer cells further demonstrated that calpain activation and endoplasmic reticulum stress contributed to cell death. These findings suggest that GA-DM is a candidate for future drug design for prostate cancer as it activates multiple pathways of cell death and immune recognition.

Alpha-enolase regulates the malignant phenotype of pulmonary artery smooth muscle cells via the AMPK-Akt pathway

The molecular mechanisms underlying the metabolic shift toward increased glycolysis observed in pulmonary artery smooth muscle cells (PASMC) during the pathogenesis of pulmonary arterial hypertension (PAH) are not fully understood. Here we show that the glycolytic enzyme α-enolase (ENO1) regulates the metabolic reprogramming and malignant phenotype of PASMC. We show that ENO1 levels are elevated in patients with associated PAH and in animal models of hypoxic pulmonary hypertension (HPH). The silencing or inhibition of ENO1 decreases PASMC proliferation and de-differentiation, and induces PASMC apoptosis, whereas the overexpression of ENO1 promotes a synthetic, de- differentiated, and apoptotic-resistant phenotype via the AMPK-Akt pathway. The suppression of ENO1 prevents the hypoxia-induced metabolic shift from mitochondrial respiration to glycolysis in PASMC. Finally, we find that pharmacological inhibition of ENO1 reverses HPH in mice and rats, suggesting ENO1 as a regulator of pathogenic metabolic reprogramming in HPH.

New Insights into the Role of Neuron-Specific Enolase in Neuro-Inflammation, Neurodegeneration, and Neuroprotection

Neurodegeneration is a complex process that leads to irreversible neuronal damage and death in spinal cord injury (SCI) and various neurodegenerative diseases, which are serious, debilitating conditions. Despite exhaustive research, the cause of neuronal damage in these degenerative disorders is not completely understood. Elevation of cell surface α-enolase activates various inflammatory pathways, including the production of pro-inflammatory cytokines, chemokines, and some growth factors that are detrimental to neuronal cells. While α-enolase is present in all neurological tissues, it can also be converted to neuron specific enolase (NSE). NSE is a glycolytic enzyme found in neuronal and neuroendocrine tissues that may play a dual role in promoting both neuroinflammation and neuroprotection in SCI and other neurodegenerative events. Elevated NSE can promote ECM degradation, inflammatory glial cell proliferation, and actin remodeling, thereby affecting migration of activated macrophages and microglia to the injury site and promoting neuronal cell death. Thus, NSE could be a reliable, quantitative, and specific marker of neuronal injury. Depending on the injury, disease, and microenvironment, NSE may also show neurotrophic function as it controls neuronal survival, differentiation, and neurite regeneration via activation of phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) signaling pathways. This review discusses possible implications of NSE expression and activity in neuroinflammation, neurodegeneration, and neuroprotection in SCI and various neurodegenerative diseases for prognostic and therapeutic potential.