The Role of Oxidative Stress in Amyotrophic Lateral Sclerosis and Parkinson’s Disease

We examined oxidative stress markers of 31 patients suffering from ALS, 24 patients suffering from PD and 30 healthy subjects were included. We determined the plasma levels of lipid peroxidation (malondialdehyde, MDA), of protein oxidative lesions (plasma glutathione, carbonyls and thiols) and the activity of antioxidant enzymes i.e. erythrocyte Cu,Zn-Superoxide dismutase (SOD), Glutathione peroxidase (GSH-Px) and catalase. MDA and thiols were significantly different in both neurodegenerative diseases versus control population. A trend for an enhancement of oxidized glutathione was noted in ALS patients. Univariate analysis showed that SOD activity was significantly decreased in ALS and GSH-Px activity was decreased in PD. After adjusting for demographic parameters and enzyme cofactors, we could emphasize a compensatory increase of SOD activity in PD. Different antioxidant systems were not involved in the same way in ALS and PD, suggesting that oxidative stress may be a cause rather than a consequence of the neuronal death.     

Neuroprotective Effects of Protocatechuic Aldehyde against Neurotoxin-Induced Cellular and Animal Models of Parkinson’s Disease

Protocatechuic aldehyde (PAL) has been reported to bind to DJ-1, a key protein involved in Parkinson’s disease (PD), and exerts potential neuroprotective effects via DJ-1 in SH-SY5Y cells. In this study, we investigated the neuroprotective pharmacological effects of PAL against neurotoxin-induced cell and animal models of PD. In cellular models of PD, PAL markedly increased cell viability rates, mitochondrial oxidation-reduction activity and mitochondrial membrane potential, and reduced intracellular ROS levels to prevent neurotoxicity in PC12 cells. In animal models of PD, PAL reduced the apomorphine injection, caused turning in 6-OHDA treated rats, and increased the motor coordination and stride decreases in MPTP treated mice. Meanwhile, in an MPTP mouse model, PAL prevented a decrease of the contents of dopamine (DA) and its metabolites in the striatum and TH-positive dopaminergic neuron loss in the substantia nigra (SN). In addition, PAL increased the protein expression of DJ-1 and reduced the level of α-synuclein in the SN of MPTP lesioned mice. PAL also increased the spine density in hippocampal CA1 neurons. The current study demonstrates that PAL can efficiently protect dopaminergic neurons against neurotoxin injury in vitro and in vivo, and that the potential mechanisms may be related to its effects in increasing DJ-1, decreasing α-synuclein and its growth-promoting effect on spine density.     

Icariin: A Potential Neuroprotective Agent in Alzheimer’s Disease and Parkinson’s Disease

Alzheimer’s disease (AD) and Parkinson’s disease (PD) are the most common neurodegenerative diseases worldwide. They are characterized by the loss of neurons and synapses in special parts of the central nervous system (CNS). There is no definitive treatment for AD and PD, but extensive studies are underway to identify the effective drugs which can slow the progression of these diseases by affecting the factors involved in their pathophysiology (i.e., aggregated proteins, neuroinflammation, and oxidative stress). Icariin, a natural compound isolated from Epimedii herba, is known because of its anti-inflammatory and anti-oxidant properties. In this regard, there are numerous studies indicating its potential as a natural compound against the progression of CNS disorders, such as neurodegenerative diseases. Therefore, this review aims to re-examine findings on the pharmacologic effects of icariin on factors involved in the pathophysiology of AD and PD.

     

The Neuroprotective Effect of Overexpression of Calbindin-D28k in an Animal Model of Parkinson’s Disease

Overexpression of calbindin-D_28k (CaBP-28 k) induces neurite outgrowth in dopaminergic neuronal cells and could provide some protection to dopaminergic neurons against the pathological process in Parkinson’s disease. Transgenic mice CaBP-28 k overexpression and the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced mouse models were generated, and the effect of midbrain dopamine neurons in ethology was also assessed. Tyrosine hydroxylase (TH)-immunoreactive neurons were counted, and the concentration of total protein and dopamine (DA) of striatum corpora was measured in four animal models. Results showed that the positive TH cells, content of DA, and ability of ethology in MPTP-induced transgenic mice were significantly higher than that in MPTP-induced wild-type mice. The findings demonstrate that overexpression of CaBP-28 k could provide protection for DA neurons from neurodegeneration. It would provide a potential strategy in the treatment of Parkinson’s diseases.     

The Neurobiology of LRRK2 and its Role in the Pathogenesis of Parkinson’s Disease

Leucine-rich repeat kinase 2 (LRRK2) is a large, widely expressed protein of largely unknown function. Mutations in the gene encoding LRRK2 have been linked to multiple diseases, including a prominent association with familial and sporadic Parkinson’s disease (PD), as well as inflammatory bowel disorders such as Crohn’s disease. The LRRK2 protein possesses both kinase and GTPase signaling domains, as well as multiple protein interaction domains. Experimental studies in both cellular and in vivo models of mutant LRRK2-induced neurodegeneration have given clues to potential function(s) of LRRK2, yet much remains unknown. For example, while it is known that intact kinase and GTPase activity are required for mutant forms of the protein to trigger cell death, the specific targets of these enzymatic activities that mediate the death of neurons are not known. In this review, we discuss the evidence linking LRRK2 to various cellular/neuronal activities such as extrinsic death and inflammatory signaling, lysosomal protein degradation, the cytoskeletal system and neurite outgrowth, vesicle trafficking, mitochondrial dysfunction, as well as multiple points of interaction with several other genes linked to the pathogenesis of PD. In order for more effective therapeutic strategies to be envisioned and implemented, the mechanisms underlying LRRK2-mediated neurodegeneration need to be better characterized. Furthermore, insights into LRRK2-associated PD pathogenesis can potentially advance our understanding of the more common sporadic forms of PD.     

A Novel GTP-Binding Inhibitor,FX2149, Attenuates LRRK2 Toxicity in Parkinson’s Disease Models

Leucine-rich repeat kinase-2 (LRRK2), a cytoplasmic protein containing both GTP binding and kinase activities, has emerged as a highly promising drug target for Parkinson’s disease (PD). The majority of PD-linked mutations in LRRK2 dysregulate its GTP binding and kinase activities, which may contribute to neurodegeneration. While most known LRRK2 inhibitors are developed to target the kinase domain, we have recently identified the first LRRK2 GTP binding inhibitor, 68, which not only inhibits LRRK2 GTP binding and kinase activities with high potency in vitro, but also reduces neurodegeneration. However, the in vivo effects of 68 are low due to its limited brain penetration. To address this problem, we reported herein the design and synthesis of a novel analog of 68, FX2149, aimed at increasing the in vivo efficacy. Pharmacological characterization of FX2149 exhibited inhibition of LRRK2 GTP binding activity by ~90% at a concentration of 10 nM using in vitro assays. Furthermore, FX2149 protected against mutant LRRK2-induced neurodegeneration in SH-SY5Y cells at 50-200 nM concentrations. Importantly, FX2149 at 10 mg/kg (i.p.) showed significant brain inhibition efficacy equivalent to that of 68 at 20 mg/kg (i.p.), determined by mouse brain LRRK2 GTP binding and phosphorylation assays. Furthermore, FX2149 at 10 mg/kg (i.p.) attenuated lipopolysaccharide (LPS)-induced microglia activation and LRRK2 upregulation in a mouse neuroinflammation model comparable to 68 at 20 mg/kg (i.p.). Our results highlight a novel GTP binding inhibitor with better brain efficacy, which represents a new lead compound for further understanding PD pathogenesis and therapeutic studies.     

The Potential Neuroprotection Mechanism of GDNF in the 6-OHDA-Induced Cellular Models of Parkinson’s Disease

The glial cell line-derived neurotrophic factor (GDNF) potential as a therapeutic agent for the treatment of Parkinson’s Disease (PD) has been extensively explored. However, the mechanism of the GDNF neuroprotective effects is still unclear. In this study, the neuroprotective mechanism of the GDNF in the PD cellular models, which was obtained by the 6-hydroxydopamine (6-OHDA)-induced dopaminergic (DA) cell line MN9D damage was investigated by microarray. Interestingly, 54 constitutively increased or decreased genes were detected, 17 of which have not been reported previously. The expression of 5 up-regulated and 5 down-regulated genes which displayed the most obvious changes compared to the no GDNF treatment cells and was previously proven to be related to cell survival was validated by real-time PCR and western blot. Moreover, the up-regulated gene Ager and down-regulated gene Ccnl2 which were related to the PI-3K/Akt signaling pathway, but not researched in the neuron-cells, were investigated by overexpression and RNA interference. Overexpression of Ager or knockdown the expression of Ccnl2 decreased the damage to MN9D cells caused by 6-OHDA and reduced their apoptosis. All these results suggested that the protective effects of the GDNF on the 6-OHDA damaged MN9D cells could be understood by enhancing the expression of the apoptosis inhibiting genes and decreasing the expression of the apoptosis promoting genes. Thus, this study might provide a number of specific candidates and potential targets to investigate the protective mechanism of GDNF in DA neurons.     

Olfaction in Three Genetic and Two MPTP-Induced Parkinson’s Disease Mouse Models

Various genetic or toxin-induced mouse models are frequently used for investigation of early PD pathology. Although olfactory impairment is known to precede motor symptoms by years, it is not known whether it is caused by impairments in the brain, the olfactory epithelium, or both. In this study, we investigated the olfactory function in three genetic Parkinson’s disease (PD) mouse models and mice treated with MPTP intraperitoneally and intranasally. To investigate olfactory function, we performed electro-olfactogram recordings (EOGs) and an olfactory behavior test (cookie-finding test). We show that neither a parkin knockout mouse strain, nor intraperitoneal MPTP treated animals display any olfactory impairment in EOG recordings and the applied behavior test. We also found no difference in the responses of the olfactory epithelium to odorants in a mouse strain over-expressing doubly mutated α-synuclein, while this mouse strain was not suitable to test olfaction in a cookie-finding test as it displays a mobility impairment. A transgenic mouse expressing mutated α-synuclein in dopaminergic neurons performed equal to control animals in the cookie-finding test. Further we show that intranasal MPTP application can cause functional damage of the olfactory epithelium.     

The Chemical Molecule B355252 is Neuroprotective in an In Vitro Model of Parkinson’s Disease

6-Hydroxydopamine (6-OHDA) is a neurotoxin frequently used to create in vitro and in vivo experimental models of Parkinson’s disease (PD), a chronic neurodegenerative disorder largely resulting from damage to the nigrostriatal dopaminergic pathway. No effective drugs or therapies have been developed for this devastating disorder, and current regimens of symptomatic therapeutics only alleviate symptoms temporarily. Therefore, effective treatments that reverse or cure this disorder are urgently needed. The aim of the study described in this report was to investigate the therapeutic impact of B355252, an aryl thiophene sulfonamide chemical entity, in the widely recognized in vitro model of PD, and to characterize the molecular signaling pathways. We show here that 6-OHDA-induced cell death in HT22, a murine neuronal cell model, through a pathway that involves the mitochondria by increasing the levels of reactive oxygen species (ROS), raising intracellular calcium ([Ca²⁺]i), enhancing the release of cytochrome c to the cytosol, and promoting activation of stress-activated protein kinase/c-Jun NH₂-terminal kinase (SAPK/JNK) signaling pathway. More importantly, we found that B355252 protected HT22 neurons against 6-OHDA toxin-induced neuronal cell death by significant attenuation of ROS production, blocking of mitochondrial depolarization, inhibition of cytochrome c release, sequestration of [Ca²⁺]i, modulation of JNK cascade, and strong inhibition of caspase 3/7 cleavage. Overall, this study demonstrates that death of neurons under toxic conditions characteristic of PD can be efficiently halted by B355252 and suggests that further development of the molecule could be potentially beneficial as a therapeutic prevention or treatment option for PD.     

Elevated Levels of IFN-γ in CSF and Serum of Patients with Amyotrophic Lateral Sclerosis

Objectives

To explore whether the levels of IFN-γ in cerebral spinal fluid (CSF) and serum are elevated in ALS patients and to analyze the correlations between the IFN-γ levels and disease progression.

Methods

CSF and serum samples were obtained from 52 ALS patients and 31 non-ALS patients. The levels of IFN-γ in CSF and serum were assessed, and disease progression parameters, including the disease interval (months from onset, MFO), the revised ALS Functional Rating Scale (ALSFRS-r) score and the disease progression rate (DPR) were analyzed by registered neurologists. All samples were measured using a commercial enzyme-linked immunosorbent assay. Statistical analyses were performed using Prism software.

Results

Compared to the non-ALS patients, the ALS patients displayed significantly increased levels of IFN-γ in both CSF and serum, and these values consistently correlated with disease progression.

Conclusions

These results demonstrated that IFN-γ in CSF may serve as a biomarker of ALS differentiation and progression. CSF IFN-γ was a more reliable biomarker of disease diagnosis and progression than serum IFN-γ.     

Metabolomics and In-Silico Analysis Reveal Critical Energy Deregulations in Animal Models of Parkinson’s Disease

Parkinson’s disease (PD) is a multifactorial disease known to result from a variety of factors. Although age is the principal risk factor, other etiological mechanisms have been identified, including gene mutations and exposure to toxins. Deregulation of energy metabolism, mostly through the loss of complex I efficiency, is involved in disease progression in both the genetic and sporadic forms of the disease. In this study, we investigated energy deregulation in the cerebral tissue of animal models (genetic and toxin induced) of PD using an approach that combines metabolomics and mathematical modelling. In a first step, quantitative measurements of energy-related metabolites in mouse brain slices revealed most affected pathways. A genetic model of PD, the Park2 knockout, was compared to the effect of CCCP, a complex I blocker. Model simulated and experimental results revealed a significant and sustained decrease in ATP after CCCP exposure, but not in the genetic mice model. In support to data analysis, a mathematical model of the relevant metabolic pathways was developed and calibrated onto experimental data. In this work, we show that a short-term stress response in nucleotide scavenging is most probably induced by the toxin exposure. In turn, the robustness of energy-related pathways in the model explains how genetic perturbations, at least in young animals, are not sufficient to induce significant changes at the metabolite level.     

The Expression and Release of Hsp60 in 6-OHDA Induced In Vivo and In Vitro Models of Parkinson’s Disease

In Parkinson’s disease, dopaminergic neuron damage/death causes the release of soluble substances that are selectively toxic to neighboring/additional dopaminergic neurons through the activation of microglia. Hsp60 can be released from injured cells of central nervous system to activate microglia. However, its expression and role in Parkinson’s disease has not been well understood. Here, we performed a 6-OHDA treated Parkinson’s disease model in adult rats. Western blot analysis showed a time-course expression of Hsp60, which decreased gradually and then rose back. Immunofluorescence staining showed that Hsp60 was decreased in dopaminergic neuron, and most Hsp60 located on the surface of activated microglia. Furthermore, in cellular Parkinson’s disease model, Hsp60 was obviously detected in the culture supernatants after 6-OHDA treatment, and a concomitant decrease in cell extracts. Taken together, our results suggested that Hsp60 could be released extracellularly to activate microglia in Parkinson’s disease model.     

The Inflammatory Marker YKL-40 Is Elevated in Cerebrospinal Fluid from Patients with Alzheimer’s but Not Parkinson’s Disease or Dementia with Lewy Bodies

A major difference in the revised diagnostic criteria for Alzheimer’s disease (AD) is the incorporation of biomarkers to support a clinical diagnosis and allow the identification of preclinical AD due to AD neuropathological processes. However, AD-specific fluid biomarkers which specifically distinguish clinical AD dementia from other dementia disorders are still missing. Here we aimed to evaluate the disease-specificity of increased YKL-40 levels in cerebrospinal fluid (CSF) from AD patients with mild to moderate dementia (n = 49) versus Parkinson’s disease (PD) (n = 61) and dementia with Lewy bodies (DLB) patients (n = 36), and non-demented controls (n = 44). Second we aimed to investigate whether altered YKL-40 levels are associated with CSF levels of other inflammation-associated molecules. When correcting for age, AD patients exhibited 21.3%, 27.7% and 38.8% higher YKL-40 levels compared to non-demented controls (p = 0.0283), DLB (p = 0.0027) and PD patients (p<0.0001). The AD-associated increase in YKL-40 was not associated with CSF P-tau, T-tau or Aβ42. No relationship between increased YKL-40 and levels of the astrocytic marker glial-fibrillary acidic protein (GFAP), interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1) and interferon gamma-induced protein 10 (IP-10) could be identified. Our results confirm previous reports of an age-associated increased in CSF YKL-40 levels and further demonstrate increased CSF YKL-40 in AD patients versus non-demented controls and patients with DLB or PD. The increase in YKL-40 levels in the AD patients was unrelated to the established CSF AD biomarkers and the inflammatory markers GFAP, MCP-1, IP-10 and IL-8, proposing YKL-40 as a marker of yet to be identified AD-related pathological processes.     

Intraventricular Sialidase Administration Enhances GM1 Ganglioside Expression and Is Partially Neuroprotective in a Mouse Model of Parkinson’s Disease

Background

Preclinical and clinical studies have previously shown that systemic administration of GM1 ganglioside has neuroprotective and neurorestorative properties in Parkinson’s disease (PD) models and in PD patients. However, the clinical development of GM1 for PD has been hampered by its animal origin (GM1 used in previous studies was extracted from bovine brains), limited bioavailability, and limited blood brain barrier penetrance following systemic administration.

Objective

To assess an alternative therapeutic approach to systemic administration of brain-derived GM1 to enhance GM1 levels in the brain via enzymatic conversion of polysialogangliosides into GM1 and to assess the neuroprotective potential of this approach.

Methods

We used sialidase from Vibrio cholerae (VCS) to convert GD1a, GD1b and GT1b gangliosides to GM1. VCS was infused by osmotic minipump into the dorsal third ventricle in mice over a 4-week period. After the first week of infusion, animals received MPTP injections (20 mg/kg, s.c., twice daily, 4 hours apart, for 5 consecutive days) and were euthanized 2 weeks after the last injection.

Results

VCS infusion resulted in the expected change in ganglioside expression with a significant increase in GM1 levels. VCS-treated animals showed significant sparing of striatal dopamine (DA) levels and substantia nigra DA neurons following MPTP administration, with the extent of sparing of DA neurons similar to that achieved with systemic GM1 administration.

Conclusion

The results suggest that enzymatic conversion of polysialogangliosides to GM1 may be a viable treatment strategy for increasing GM1 levels in the brain and exerting a neuroprotective effect on the damaged nigrostriatal DA system.     

BIN1 Is Decreased in Sporadic but Not Familial Alzheimer’s Disease or in Aging

Bridging integrator 1 (BIN1) has been implicated in sporadic Alzheimer’s disease (AD) by a number of genome wide association studies (GWAS) in a variety of populations. Here we measured BIN1 in frontal cortex samples from 24 sporadic AD and 24 age-matched non-dementia brains and correlated the expression of this protein with markers of AD. BIN1 was reduced by 87% (p=0.007) in sporadic AD compared to non-dementia controls, but BIN1 in sporadic AD did not correlate with soluble Aβ (r_s=-0.084, p=0.698), insoluble Aβ (r_s=0.237, p=0.269), Aβ plaque load (r_s=0.063, p=0.771) or phospho-tau load (r_s=-0.160, p=0.489). In contrast to our findings in sporadic AD, BIN1 was unchanged in the hippocampus from 6 cases of familial AD compared to 6 age-matched controls (p=0.488). BIN1 declined with age in a cohort of non-dementia control cases between 25 and 88 years but the correlation was not significant (r_s=-0.449, p=0.081). Although BIN1 is known to have a role in endocytosis, and the processing of the amyloid precursor protein (APP) to form amyloid-β (Aβ) peptides is dependent on endocytosis, knockdown of BIN1 by targeted siRNA or the overexpression of BIN1 in a human neuroblastoma cell line (SH-SY5Y) had no effect on APP processing. These data suggest that the alteration in BIN1 is involved in the pathogenesis of sporadic, but not familial AD and is not a consequence of AD neurodegeneration or the ageing process, a finding in keeping with the numerous GWAS that implicate BIN1 in sporadic AD. However, the mechanism of its contribution remains to be established.     

Melatonin as a Neuroprotective Agent in the Rodent Models of Parkinson’s Disease: Is it All Set to Irrefutable Clinical Translation?

Parkinson’s disease (PD), a neurodegenerative disorder, is characterized by the selective degeneration of the nigrostriatal dopaminergic neurons, continuing or permanent deficiency of dopamine, accretion of an abnormal form of alpha synuclein in the adjacent neurons, and dysregulation of ubiquitin proteasomal system, mitochondrial metabolism, permeability and integrity, and cellular apoptosis resulting in rigidity, bradykinesia, resting tremor, and postural instability. Melatonin, an indoleamine produced almost in all the organisms, has anti-inflammatory, anti-apoptotic, and anti-oxidant nature. Experimental studies employing 1-methyl 4-phenyl 1, 2, 3, 6-tetrahydropyridine (MPTP), 6-hydroxydopamine (6-OHDA), methamphetamine, rotenone, and maneb and paraquat models have shown an enormous potential of melatonin in amelioration of the symptomatic features of PD. Although a few reviews published previously have described the multifaceted efficacy of melatonin against MPTP and 6-OHDA rodent models, due to development and validation of the newer models as well as the extensive studies on the usage of melatonin in entrenched PD models, it is worthwhile to bring up to date note on the usage of melatonin as a neuroprotective agent in PD. This article presents an update on the usage and applications of melatonin in PD models along with incongruous observations. The impending implications in the clinics, success, limitations, and future prospective have also been discussed in this article.     

Cerebral Metabolic Differences Associated with Cognitive Impairment in Parkinson’s Disease

PurposeTo characterize cerebral glucose metabolism associated with different cognitive states in Parkinson’s disease (PD) using ¹⁸F-fluorodeoxyglucose (FDG) and Positron Emission Tomography (PET).MethodsThree groups of patients were recruited in this study including PD patients with dementia (PDD; n = 10), with mild cognitive impairment (PD-MCI; n = 20), and with no cognitive impairment (PD-NC; n = 30). The groups were matched for age, sex, education, disease duration, motor disability, levodopa equivalent dose and Geriatric Depression Rating Scale (GDS) score. All subjects underwent a FDG-PET study. Maps of regional metabolism in the three groups were compared using statistical parametric mapping (SPM5).ResultsPD-MCI patients exhibited limited areas of hypometabolism in the frontal, temporal and parahippocampal gyrus compared with the PD-NC patients (p < 0.01). PDD patients had bilateral areas of hypometabolism in the frontal and posterior parietal-occipital lobes compared with PD-MCI patients (p < 0.01), and exhibited greater metabolic reductions in comparison with PD-NC patients (p < 0.01).ConclusionsCompared with PD-NC patients, hypometabolism was much higher in the PDD patients than in PD-MCI patients, mainly in the posterior cortical areas. The result might suggest an association between posterior cortical hypometabolism and more severe cognitive impairment. PD-MCI might be important for early targeted therapeutic intervention and disease modification.     

The Lewy Body in Parkinson’s Disease and Related Neurodegenerative Disorders

The histopathological hallmark of Parkinson’s disease (PD) is the presence of fibrillar aggregates referred to as Lewy bodies (LBs), in which α-synuclein is a major constituent. Pale bodies, the precursors of LBs, may serve the material for that LBs continue to expand. LBs consist of a heterogeneous mixture of more than 90 molecules, including PD-linked gene products (α-synuclein, DJ-1, LRRK2, parkin, and PINK-1), mitochondria-related proteins, and molecules implicated in the ubiquitin–proteasome system, autophagy, and aggresome formation. LB formation has been considered to be a marker for neuronal degeneration because neuronal loss is found in the predilection sites for LBs. However, recent studies have indicated that nonfibrillar α-synuclein is cytotoxic and that fibrillar aggregates of α-synuclein (LBs and pale bodies) may represent a cytoprotective mechanism in PD.