Gender differences in risk factors for high plasma homocysteine levels based on a retrospective checkup cohort using a generalized estimating equation analysis.

BACKGROUND: Hyperhomocysteinemia (HHcy) is associated with various health problems, but less is known about the gender differences in risk factors for high plasma homocysteine (Hcy) levels. METHODS: In this study, a retrospective study was carried out on 14,911 participants (7838 males and 7073 females) aged 16-102 years who underwent routine checkups between January 2012 and December 2017 in the Health Management Department of Xuanwu Hospital, China. Anthropometric measurements, including body mass index (BMI) and waist-to-hip ratio, were collected. Fasting blood samples were collected to measure the biochemical indexes. The outcome variable was Hcy level, and a generalized estimating equation (GEE) analysis was used to identify the associations of interest based on gender. RESULTS: Males exhibited increased Hcy levels (16.37 ± 9.66 vs 11.22 ± 4.76 µmol/L) and prevalence of HHcy (37.0% vs 11.3%) compared with females. Hcy levels and HHcy prevalence increased with age in both genders, except for the 16- to 29-year-old group. GEE analysis indicated that irrespective of gender, aspartate aminotransferase, creatinine, uric acid, low-density lipoprotein cholesterol and high-density lipoprotein cholesterol levels were positively correlated with Hcy levels, and alanine aminotransferase, total cholesterol and glucose were negatively correlated with Hcy levels. However, age, BMI and triglycerides (TGs) were positively correlated with Hcy levels exclusively in females. CONCLUSIONS: Gender differences in risk factors for high plasma Hcy levels were noted. Although common correlational factors existed in both genders, age, BMI and TGs were independent risk factors for Hcy levels specifically in females.

The Role of Iron in Amyotrophic Lateral Sclerosis.

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disorder characterized by the degeneration of motor neurons in the motor cortex, brainstem, and spinal cord. The etiology and pathogenesis of this devastating disease remain largely unknown. Increasing evidence suggests that iron accumulation is involved in the onset and progression of ALS. In this review, we discuss the regulation of iron homoeostasis in the brain, the misregulation of iron homeostasis in ALS, and its possible roles in the mechanism of the disease. Finally, we summarize the recent progress and problems with respect to iron chelator therapies on ALS, aiming to propose a new therapeutic strategy to ameliorate the progression of the disease.

Diallyl Trisulfide Protects Motor Neurons from the Neurotoxic Protein TDP-43 via Activating Lysosomal Degradation and the Antioxidant Response.

Amyotrophic lateral sclerosis (ALS) is a rapidly progressive motor neuron disease for which only limited effective therapeutics are available. Currently, TAR DNA-binding protein 43 (TDP-43) is recognized as a pathological and biochemical marker for ALS. Increases in the levels of aggregated or mislocalized forms of TDP-43 might result in ALS pathology. Therefore, clearance pathways for intracellular protein aggregates have been suggested as potential therapeutic targets for the treatment of ALS. Here we report that treatment of motor neuron-like NSC34 cells overexpressing TDP-43 with diallyl trisulfide (DATS) induced neuronal autophagy and lysosomal clearance of TDP-43 and C-terminal TDP-43 fragments. We also observed that the antioxidant transcription factor NF-E2-related factor 2 (Nrf2) was accumulated in the nucleus and the expression of the antioxidant enzymes heme oxygenase1 (HO-1) and NAD(P)H:quinone oxidoreductase (NQO1) was increased. Consequently, DATS suppressed the increase in the levels of reactive oxygen species induced by TDP-43 expression. This study extends the findings of prior reports indicating that lower doses of DATS mediate cell survival in part by inducing autophagy and activating the Nrf2/antioxidant response element pathway.

Widespread spinal cord transduction by intrathecal injection of rAAV delivers efficacious RNAi therapy for amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) causes motor neuron degeneration and paralysis. No treatment can significantly slow or arrest the disease progression. Mutations in the SOD1 gene cause a subset of familial ALS by a gain of toxicity. In principle, these cases could be treated with RNAi that destroys the mutant mRNA, thereby abolishing the toxic protein. However, no system is available to efficiently deliver the RNAi therapy. Recombinant adenoassociated virus (rAAV) is a promising vehicle due to its long-lasting gene expression and low toxicity. However, ALS afflicts broad areas of the central nervous system (CNS). A lack of practical means to spread rAAV broadly has hindered its application in treatment of ALS. To overcome this barrier, we injected several rAAV serotypes into the cerebrospinal fluid. We found that some rAAV serotypes such as rAAVrh10 and rAAV9 transduced cells throughout the length of the spinal cord following a single intrathecal injection and in the broad forebrain following a single injection into the third ventricle. Furthermore, a single intrathecal injection of rAAVrh10 robustly transduced motor neurons throughout the spinal cord in a non-human primate. These results suggested a therapeutic potential of this vector for ALS. To test this, we injected a rAAVrh10 vector that expressed an artificial miRNA targeting SOD1 into the SOD1G93A mice. This treatment knocked down the mutant SOD1 expression and slowed the disease progression. Our results demonstrate the potential of rAAVs for delivering gene therapy to treat ALS and other diseases that afflict broad areas of the CNS.

Global CNS transduction of adult mice by intravenously delivered rAAVrh.8 and rAAVrh.10 and nonhuman primates by rAAVrh.10.

Some recombinant adeno-associated viruses (rAAVs) can cross the neonatal blood-brain barrier (BBB) and efficiently transduce cells of the central nervous system (CNS). However, in the adult CNS, transduction levels by systemically delivered rAAVs are significantly reduced, limiting their potential for CNS gene therapy. Here, we characterized 12 different rAAVEGFPs in the adult mouse CNS following intravenous delivery. We show that the capability of crossing the adult BBB and achieving widespread CNS transduction is a common character of AAV serotypes tested. Of note, rAAVrh.8 is the leading vector for robust global transduction of glial and neuronal cell types in regions of clinical importance such as cortex, caudate-putamen, hippocampus, corpus callosum, and substantia nigra. It also displays reduced peripheral tissue tropism compared to other leading vectors. Additionally, we evaluated rAAVrh.10 with and without microRNA (miRNA)-regulated expressional detargeting from peripheral tissues for systemic gene delivery to the CNS in marmosets. Our results indicate that rAAVrh.8, along with rh.10 and 9, hold the best promise for developing novel therapeutic strategies to treat neurological diseases in the adult patient population. Additionally, systemically delivered rAAVrh.10 can transduce the CNS efficiently, and its transgene expression can be limited in the periphery by endogenous miRNAs in adult marmosets.

Bioinformatics analysis reveals multiple functional changes in astrocytes in temporal lobe epilepsy.

Epilepsy is a prevalent chronic neurological disorder characterized by recurrent seizures and brain dysfunction. Existing antiepileptic drugs (AEDs) mainly act on neurons and provide symptomatic control of seizures, but they do not modify the progression of epilepsy and may cause serious adverse effects. Increasing evidence suggests that reactive astrogliosis is critical in the pathophysiology of epilepsy. However, the function of reactive astrocytes in epilepsy has not been thoroughly explored. To provide a new perspective on the role of reactive astrocytes in epileptogenesis, we identified human astrocyte-specific genes and found 131 of these genes significantly differentially expressed in human temporal lobe epilepsy (TLE) datasets. Multiple astrocytic functions, such as cell adhesion, cell morphogenesis, actin filament-based process, apoptotic cell clearance and response to oxidative stress, were found to be promoted. Moreover, multiple altered astrocyte-specific genes were enriched in phagocytosis, perisynaptic astrocyte processes (PAPs), plasticity, and synaptic functions. Nine hub genes (ERBB2, GFAP, NOTCH2, ITGAV, ABCA1, AQP4, LRP1, GJA1, and YAP1) were identified by protein-protein interaction (PPI) network analysis. The correlation between the expression of these hub genes and seizure frequency, as well as epilepsy-related factors, including inflammatory mediators, complement factors, glutamate excitotoxicity and astrocyte reactivity, were analyzed. Additionally, upstream transcription factors of the hub genes were predicted. Finally, astrogliosis and the expression of the hub genes were validated in an epileptic rat model. Our findings reveal the various changes in astrocyte function associated with epilepsy and provide candidate astrocyte-specific genes that could be potential antiepileptogenic targets.

The Association Between the Composite Dietary Antioxidant Index and Frailty Symptoms: Mediating Effects of Oxidative Stress.

Background: There is growing evidence that an antioxidant diet is a protective factor against frailty. However, few studies have examined the effect of comprehensive dietary antioxidants on frailty symptoms. The aim of this study was to examine the relationships between the composite dietary antioxidant index (CDAI) and frailty and the underlying mechanisms involved. Methods: Based on the National Health and Nutrition Survey (NHANES) 2003-2018, this study included 11,277 older persons aged ≥60 years. In this study, frailty was defined as having a total score >0.21 on the 49-item frailty index. Six dietary antioxidants were selected for use in calculating the CDAI. A weighted multiple logistic regression model with subgroup analysis and restricted cubic splines (RCSs) were used to examine the association between the CDAI and frailty. To examine the role of oxidative stress, mediation analyses were also conducted. Results: The association between the CDAI score and frailty risk was significant according to the multivariate model. Compared with participants in tertile 1, participants in both tertile 2 and tertile 3 had lower odds of developing frailty symptoms (OR=0.86; 95% CI=0.75-0.97; P=0.02; and OR=0.81; 95% CI=0.70-0.93; P=0.003). According to the subgroup analyses, the differences in interactions were not statistically significant. There was also a potential nonlinear relationship between the CDAI score and frailty risk. The serum albumin concentration and uric acid concentration had significant mediating effects on the association between the CDAI score and frailty index, with 19.25% (P=0.002) and 21.26% (P < 0.001) of the total, respectively. Conclusion: Frailty is negatively associated with the CDAI score, which may be partially mediated by oxidative stress.

The modest impact of transcription factor Nrf2 on the course of disease in an ALS animal model.

Oxidative stress is associated with the pathogenesis of amyotrophic lateral sclerosis (ALS). Nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway is one of the major cellular defense mechanisms against oxidative stress. However, the role of Nrf2-mediated neuroprotection (antioxidant defense) in the disease development of ALS remains unclear. To further investigate the role of Nrf2 in ALS, we genetically eliminate the Nrf2 gene from SOD1-G93A mice, a commonly used ALS mouse model, by generating a double mutant (Nrf2-/- SOD1-G93A mice). We found that it only had a modest impact on the course of disease by knocking out Nrf2 gene in these mice. Further studies demonstrated that, among previously known Nrf2-regulated phase II enzymes, only NAD(P)H: quinone oxidoreductase 1 induction was significantly affected by the elimination of Nrf2 gene in SOD1-G93A mice. Taken together, our data suggested that Nrf2 is not the sole mediator for the induction of antioxidant genes in SOD1-G93A mice, and Nrf2-mediated neuroprotection is not the key protective mechanism against neurodegeneration in those mice.

Relationship of Klotho with cognition and dementia: Results from the NHANES 2011-2014 and Mendelian randomization study.

The relationships of Klotho levels with cognition and dementia are poorly understood. This study aimed to investigate the association between Klotho levels and cognitive function and to determine causality between Klotho and dementia using Mendelian randomization (MR). Based on data from the National Health and Nutrition Survey (NHANES) 2011-2014, this study consisted of 1875 older adults aged 60-79 years. Cognitive function was assessed by the digit symbol substitution test (DSST). We performed weighted multivariable-adjusted linear regression to assess the association between Klotho concentrations and cognitive function. Then, 2-sample MR was conducted to assess the causal relationship between Klotho and dementia. The inverse variance weighted (IVW) method was used as the primary analysis. We observed a positive association between serum Klotho concentrations and the results of the Digit Symbol Substitution test (DSST) (T2: ß 2.16, 95% CI: 0.30-4.01, P = 0.03, T3: ß 2.48, 95% CI: 0.38-4.57, P = 0.02) after adjusting for the covariates. Moreover, there was also a potential nonlinear relationship between Klotho and DSST. The IVW method showed that genetically predicted high Klotho levels were not significantly associate with any type of dementia, including Alzheimer's disease (OR = 1.03, 95% CI: 0.96-1.10, P = 0.46), vascular dementia (OR = 1.04, 95% CI: 0.87-1.25, P = 0.66), frontotemporal dementia (OR = 0.73, 95% CI: 0.47-1.14, P = 0.16), or dementia with Lewy bodies (OR = 1.03, 95% CI: 0.87-1.23, P = 0.73). In the cross-sectional observational study, Klotho and cognitive function were significantly correlated; however, findings from MR studies did not indicate a causal relationship between Klotho and dementia.

Factors Related to Plasma Homocysteine Concentration in Young Adults: A Retrospective Study Based on Checkup Populations.

The distribution profile of plasma homocysteine (Hcy) in young adults and its related factors are not well understood. We performed a generalized estimating equations (GEE) analysis for plasma-Hcy-correlated factors in 2436 young adults, aged 20-39 years, from a health checkup population. We observed that the mean Hcy concentration in males (16.7 ± 10.3 µmol/L) was significantly higher than that in females (10.3 ± 4.0 µmol/L), and hyperhomocysteinemia (HHcy) prevalence in males was 5.37 times than that in females (33.3% vs. 6.2%). A GEE analysis stratified by sex indicated that age (B = -0.398, p < 0.001) and LDL-C (B = -1.602, p = 0.043) were negatively correlated, while BMI (B = 0.400, p = 0.042) was positively correlated, with the Hcy level in young males. ALT (B = -0.021, p = 0.033), LDL-C (B = -1.198, p < 0.001) and Glu (B = -0.446, p = 0.006) were negatively correlated, while AST (B = 0.022, p = 0.048), CREA (B = 0.035, p < 0.001), UA (B = 0.004, p = 0.003) and TG (B = 1.042, p < 0.001) were positively correlated, with the Hcy level in young females. These results suggest that young males have a significantly higher plasma Hcy level and HHcy prevalence than young females; therefore, more attention should be paid to the reason for and effect of the higher HHcy prevalence in young males.

Proteomics analysis indicates the involvement of immunity and inflammation in the onset stage of SOD1-G93A mouse model of ALS.

Amyotrophic lateral sclerosis (ALS) is a fatal motor neuron degenerative disease, and the pathogenic mechanism that underlies ALS is still unclear. We analyzed the differentially expressed proteins (DEPs) in the spinal cord between SOD1-G93A transgenic mice at the onset stage and non-transgenic (NTG) littermates based on 4D label-free quantitative proteomics (4D-LFQ) with liquid chromatography-tandem mass spectrometry (LC-MS/MS). In our study, 189 DEPs were screened, of which 166 were up-regulated and 23 down-regulated. Clusters of Orthologous Groups (COG)/ EuKaryotic Orthologous Groups (KOG) classification, subcellular localization annotation, Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment, clustering analysis and protein-protein interaction (PPI) network analyses were performed. Parallel reaction monitoring (PRM) analysis validated 48 proteins from immunity and inflammation-related pathways of KEGG. We described the function and distribution of DEPs, most of which were involved in the following pathways: complement and coagulation cascades, antigen processing and presentation, NF-kappa B signaling pathway, Retinoic acid-inducible gene I (RIG) -I-like receptor signaling pathway, the extracellular matrix-receptor (ECM-receptor) interaction, focal adhesion, phagosome and lysosome. PPI network analysis identified Fn1, Fga, Serpina1e and Serpina3n as potential biomarkers. Our discoveries broaden the view and expand our understanding of immunity and inflammation in ALS. SIGNIFICANCE: This study gives a comprehensive description of DEPs in the spinal cord proteomics of SOD1-G93A mice at the onset period. Compared with a previous study focusing on progressive stage, we showed that immunity and inflammation play an important role at the onset stage of ALS. Several pathways validated by PRM bring new insight to the pathological mechanisms of ALS. The participation of RIG-I-like signaling pathway in ALS and potential biomarkers Fga, Fn1, Serpina1e and Serpina3n are supplements to existing knowledge.

Endothelin-1, over-expressed in SOD1G93A mice, aggravates injury of NSC34-hSOD1G93A cells through complicated molecular mechanism revealed by quantitative proteomics analysis.

Endothelin-1 (ET-1), a secreted signaling peptide, is suggested to be involved in multiple actions in various tissues including the brain, but its role in amyotrophic lateral sclerosis (ALS) remains unknown. In this study, we detected the expression changes as well as the cellular localization of ET-1, endothelin A (ET-A) and endothelin B (ET-B) receptors in spinal cord of transgenic SOD1-G93A (TgSOD1-G93A) mice, which showed that the two ET receptors (ET-Rs) expressed mainly on neurons and decreased as the disease progressed especially ET-B, while ET-1 expression was up-regulated and primarily localized on astrocytes. We then explored the possible mechanisms underlying the effect of ET-1 on cultured NSC34-hSOD1G93A cell model. ET-1 showed toxic effect on motor neurons (MNs), which can be rescued by the selective ET-A receptor antagonist BQ-123 or ET-B receptor antagonist BQ-788, suggesting that clinically used ET-Rs pan-antagonist could be a potential strategy for ALS. Using proteomic analysis, we revealed that 110 proteins were differentially expressed in NSC34-hSOD1G93A cells after ET-1 treatment, of which 54 were up-regulated and 56 were down-regulated. Bioinformatic analysis showed that the differentially expressed proteins (DEPs) were primarily enriched in hippo signaling pathway-multiple species, ABC transporters, ErbB signaling pathway and so on. These results provide further insights on the potential roles of ET-1 in ALS and present a new promising therapeutic target to protect MNs of ALS.

Low-level overexpression of wild type TDP-43 causes late-onset, progressive neurodegeneration and paralysis in mice.

Modestly increased expression of transactive response DNA binding protein (TDP-43) gene have been reported in amyotrophic lateral sclerosis (ALS), frontotemporal dementia (FTD), and other neuromuscular diseases. However, whether this modest elevation triggers neurodegeneration is not known. Although high levels of TDP-43 overexpression have been modeled in mice and shown to cause early death, models with low-level overexpression that mimic the human condition have not been established. In this study, transgenic mice overexpressing wild type TDP-43 at less than 60% above the endogenous CNS levels were constructed, and their phenotypes analyzed by a variety of techniques, including biochemical, molecular, histological, behavioral techniques and electromyography. The TDP-43 transgene was expressed in neurons, astrocytes, and oligodendrocytes in the cortex and predominantly in astrocytes and oligodendrocytes in the spinal cord. The mice developed a reproducible progressive weakness ending in paralysis in mid-life. Detailed analysis showed ~30% loss of large pyramidal neurons in the layer V motor cortex; in the spinal cord, severe demyelination was accompanied by oligodendrocyte injury, protein aggregation, astrogliosis and microgliosis, and elevation of neuroinflammation. Surprisingly, there was no loss of lower motor neurons in the lumbar spinal cord despite the complete paralysis of the hindlimbs. However, denervation was detected at the neuromuscular junction. These results demonstrate that low-level TDP-43 overexpression can cause diverse aspects of ALS, including late-onset and progressive motor dysfunction, neuroinflammation, and neurodegeneration. Our findings suggest that persistent modest elevations in TDP-43 expression can lead to ALS and other neurological disorders involving TDP-43 proteinopathy. Because of the predictable and progressive clinical paralytic phenotype, this transgenic mouse model will be useful in preclinical trial of therapeutics targeting neurological disorders associated with elevated levels of TDP-43.

Activation of nuclear factor erythroid 2-related factor 2 cytoprotective signaling by curcumin protect primary spinal cord astrocytes against oxidative toxicity.

Oxidative damage plays a critical role in many neurodegenerative diseases. Astrocytes are involved in supporting the survival and protection of neurons against oxidative damage. The dysfunction of antioxidant in astrocytes has been implicated in a variety of neurodegenerative disorders, such as amyotrophic lateral sclerosis (ALS), spinalmuscularatrophy (SMA). The loss of motor neuron in spinal cord has been attributed to deterioration of astrocytes. The activation of antioxidantive function in astrocytes may serve as a therapeutic strategy for neurodegenerative diseases. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a master transcriptional regulator of phase II antioxidantive genes. We report herein that curcumin significantly activates Nrf2 target genes in primary spinal cord astrocytes, decreases the level of intracellular reactive oxygen species (ROS), and attenuates oxidative damage and mitochondrial dysfunction.

Glutathione S-transferase Omega 2 DD genotype is associated with an increased risk of sporadic amyotrophic lateral sclerosis in Chinese men.

OBJECTIVE: To investigate whether GSTA1, GSTO2, and GSTZ1 are relevant to an increased risk of amyotrophic lateral sclerosis (ALS) in a Chinese population. METHODS: In this study, 143 sporadic ALS (sALS) patients (83 men, 60 women) and 210 age- and sex-matched healthy subjects were enrolled. Blood samples were collected by venipuncture. Genomic DNA was isolated by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) according to the manufacturer's instructions. The potential associations between ALS and GSTA1, GSTO2, and GSTZ1 polymorphisms were estimated using chi-squared analysis and unconditional logistic regression. RESULTS: The D allele and genotype frequencies of GSTO2 were increased in sALS patients compared with healthy subjects, indicating that the GSTO2 DD genotype was associated with an increased risk of sALS (odds ratio [OR] = 3.294, 95% confidence interval [CI] = 1.039-10.448). However, a significant association between the DD genotype and the risk of sALS was evident in men only (OR = 7.167, 95% CI = 1.381-37.202). CONCLUSION: This study revealed that the D allele and genotype frequencies of GSTO2 were increased in sALS patients. The GSTO2 DD genotype was associated with an increased risk of sALS in men in a Chinese population.

Oxymatrine Extends Survival by Attenuating Neuroinflammation in a Mouse Model of Amyotrophic Lateral Sclerosis.

Amyotrophic lateral sclerosis (ALS) is one of the leading causes of death associated with neurodegenerative diseases worldwide, and the progression of the disease is characteristically accompanied by severe neuroinflammation. Neuroprotective effects of oxymatrine (OMT) were shown to be due to reduced neuroinflammation in the mouse models of Alzheimer's disease and Parkinson's disease. The present study investigated whether OMT has a therapeutic potential in transgenic SOD1-G93A (TgSOD1-G93A) mice. Daily OMT treatment started at the age of 55 days until the end stage of the disease. Body weight and rotarod motor performance were assessed every 3 days starting from 70 days of age. Footprints were recorded to measure the stride length 40 days and 60 days after the initiation of the treatment. Some animals were sacrificed at the age of 115 days, and the lumbar spinal cord was harvested for immunofluorescence and quantitative real-time polymerase chain reaction (qRT-PCR) to evaluate the neuroinflammatory responses. The results indicated that treatment with OMT delayed body weight loss, improved motor performance, and prolonged the survival of SOD1-G93A mice. Mechanistically, OMT treatment enhanced motor neuronal survival and alleviated the activation of microglia and astrocytes compared with those in the vehicle-treated group. Furthermore, the expression of the proinflammatory mediators was downregulated, and the expression of the anti-inflammatory factors was upregulated in the OMT-treated group compared with those in the vehicle-treated group (P < 0.05). Thus, the treatment with OMT had neuroprotective effects, promoting neuronal survival and extending the lifetime of SOD1-G93A mice by suppressing neuroinflammation.

Protective effect of combination of sulforaphane and riluzole on glutamate-mediated excitotoxicity.

Threohydroxyaspartate (THA) causes glutamate excitotoxicity in motor neurons in organotypic culture of rat spinal cord. Some drugs, including sulforaphane (SF) and riluzole, can protect motor neuron against excitotoxicity. It has been demonstrated that SF is a potent inducer of Phase II enzymes, while riluzole is a classic anti-glutamate agent. The objective of the current study is to investigate whether the combination of SF and riluzole is superior to either one used alone. In our study, the combination of SF with riluzole not only stimulates the expression of nuclear factor erythroid 2-related factor 2 (Nrf2), reduced nicotinamide adenine dinucleotide phosphate (NADPH): quinone oxidoreductase 1 (NQO1) and heme oxygenase 1 (HO-1), but also reduces the extracellular accumulation of glutamate. When used at optimal doses, SF (10 microM) and riluzole (5 microM), either alone or in combination, all exert significant and similar neuroprotection, as measured by the number of motor neuron, medium malondialdehyde (MDA) level and lactate dehydrogenase (LDH) level. When used at low doses, the combination is better than each agent used alone. In conclusion, these results suggest the potential utility of combination use of SF and riluzole for protection of motor neuron against excitotoxicity.

Rofecoxib Attenuates the Pathogenesis of Amyotrophic Lateral Sclerosis by Alleviating Cyclooxygenase-2-Mediated Mechanisms.

Cyclooxygenase-2 (COX-2) is reported to be activated during the course of amyotrophic lateral sclerosis (ALS) development and progression. However, the roles of COX-2 in aggravating ALS and the underlying mechanism have been largely overlooked. To reveal the mechanisms, the canonical SOD1G93A mouse model was used as an experimental model for ALS in the current study. In addition, a specific inhibitor of COX-2 activity, rofecoxib, was orally administered to SOD1G93A mice. With this in vivo approach, we revealed that COX-2 proinflammatory signaling cascades were inhibited by rofecoxib in SOD1G93A mice. Specifically, the protein levels of COX-2, interleukin (IL)-1ß, and tumor necrosis factor (TNF)-α were elevated as a result of activation of astrocytes and microglia during the course of ALS development and progression. These proinflammatory reactions may contribute to the death of neurons by triggering the movement of astrocytes and microglia to neurons in the context of ALS. Treatment with rofecoxib alleviated this close association between glial cells and neurons and significantly decreased the density of inflammatory cells, which helped to restore the number of motor neurons in SOD1G93A mice. Mechanistically, rofecoxib treatment decreased the expression of COX-2 and its downstream signaling targets, including IL-1ß and TNF-α, by deactivating glial cells, which in turn ameliorated the progression of SOD1G93A mice by postponing disease onset and modestly prolonging survival. Collectively, these results provide novel insights into the mechanisms of ALS and aid in the development of new drugs to improve the clinical treatment of ALS.

Activation of the Notch Signaling Pathway and Cellular Localization of Notch Signaling Molecules in the Spinal Cord of SOD1-G93A ALS Model Mice.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disorder characterized by motor neuron loss and gliosis in the spinal cord, brain stem and cortex. The Notch signaling pathway has been reported to be dysfunctional in neurodegenerative diseases, including ALS. However, the exact mechanism is still unclear. Here, we detected Notch signaling activation in proliferating glial cells, Notch inactivation in motor neurons in the spinal cord of the SOD1-G93A model, and dramatic changes of cellular relocalization of Notch pathway signaling molecules, including activated Notch intracellular domain (NICD), Notch ligands (Jagged1 and DLL4) and the target gene Hes1. We found that Notch activation was universal in proliferating astrocytes and that the Notch ligand Jagged1 was uniquely upregulated in proliferating microglia, while DLL4 expression was increased in both activated astrocytes and degenerating oligodendrocytes. Our results indicate that microglia may play an important role in the intercellular receptor-ligand interaction of the Notch signaling pathway and contribute to the pathogenesis of motor neuron loss in ALS mice. Further experiments are required to clarify the exact mechanism responsible for Notch dysfunction in ALS.

Neuroprotective potential of phase II enzyme inducer diallyl trisulfide.

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease, selectively involving the upper and lower motor neurons. Glutamate excitotoxicity and oxidative stress are important mechanisms for the pathogenesis of ALS. Nuclear-factor erythroid 2-related factor 2 (Nrf2) is a master transcriptional regulator of many cytoprotective genes. Nrf2 signal pathway could induce a series of antioxidant enzyme, anti-inflammatory and antitoxic protein. The expression of these antioxidant enzymes and antioxidant proteins in nervous system exhibited broad neuroprotection against injury by glutamate. Diallyl trisulfide (DATS) was previously shown to induce many Nrf2 target genes in non-nervous cells. Our studies have shown that DATS at 50 microM caused activation of Nrf2 and Nrf2 target gene in rat spinal cord explants. DATS also protected motor neurons against glutamate-induced excitotoxicity. These have identified DATS as a promising neuroprotective agent and suggest that the activation of Nrf2 signal pathway may be a new strategy in neurodegeneration disease.