An inflammatory review of Parkinson's disease

Glucagon-like peptide-1 class drugs show clear protective effects in Parkinson's and Alzheimer's disease clinical trials: A revolution in the making?

Parkinson's disease (PD) is a complex syndrome for which there is no disease-modifying treatment on the market. However, a group of drugs from the Glucagon-like peptide-1 (GLP-1) class have shown impressive improvements in clinical phase II trials. Exendin-4 (Bydureon), Liraglutide (Victoza, Saxenda) and Lixisenatide (Adlyxin), drugs that are on the market as treatments for diabetes, have shown clear effects in improving motor activity in patients with PD in phase II clinical trials. In addition, Liraglutide has shown improvement in cognition and brain shrinkage in a phase II trial in patients with Alzheimer disease (AD). Two phase III trials testing the GLP-1 drug semaglutide (Wegovy, Ozempic, Rybelsus) are ongoing. This perspective article will summarize the clinical results obtained so far in this novel research area. We are at a crossroads where GLP-1 class drugs are emerging as a new treatment strategy for PD and for AD. Newer drugs that have been designed to enter the brain easier are being developed already show improved effects in preclinical studies compared with the older GLP-1 class drugs that had been developed to treat diabetes. The future looks bright for new treatments for AD and PD.

Exploring the complex interplay between Parkinson's disease and BAG proteins

Parkinsons disease (PD) is a chronic fast growing neurodegenerative disorder of Central Nervous System (CNS) characterized by progressive loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and formation of Lewy bodies (LBs) which causes dopamine deficiency within basal ganglia leading to motor and non-motor manifestation. According to reports, many factors are responsible for pathogenesis of PD which includes environmental factors, genetic factors, and aging factors. Whereas death of dopaminergic neurons is also caused by oxidative stress, neuroinflammation, and autophagy disorder. Molecular chaperones/co-chaperones are proteins that binds to an unstable conformer of another protein and stabilizes it. Chaperones prevent incorrect interaction between non-native polypeptides which increases the yield but not the rate of reaction. The Bcl-2-associated athanogene (BAG) is a multifunctional group of proteins belonging to BAG family of co-chaperones. Recent studies demonstrates that chaperones interact with PD-related proteins. Co-chaperones like BAG family proteins regulate the function of chaperones. Molecular chaperones regulate the mitochondrial functions by interacting with the PD-related proteins associated with it. This review studies the contribution of chaperones and PD-related proteins in pathogenesis of PD aiming to provide an alternate molecular target for preventing the disease progression.

Exploring the Neuroprotective Potential of N-Methylpyridinium against LPS-Induced Neuroinflammation: Insights from Molecular Mechanisms

N-methylpyridinium (NMP) is produced through the pyrolysis of trigonelline during the coffee bean roasting process. Preliminary studies suggest that NMP may have health benefits, thanks to its antioxidant properties. Based on this background, the aim of this study was to evaluate whether NMP could have a protective effect against LPS-induced neuroinflammation in human glioblastoma cells (U87MG). With this aim, U87MG cells were pre-treated with NMP (0.5 μM) for 1 h and then exposed to LPS (1 μg/mL) for 24 h. Our findings show that NMP attenuates LPS-induced neuroinflammation by reducing the expression of pro-inflammatory cytokines, such as IL-1β, TNF-α and IL-6, through the inhibition of the NF-κB signaling pathway, which is critical in regulating inflammatory responses. NMP is able to suppress the activation of the NF-κB signaling pathway, suggesting its potential in preventing neuroinflammatory conditions. These outcomes support the notion that regular consumption of NMP, possibly through coffee consumption, may offer protection against neuroinflammatory states implicated in neurological disorders.

Study of molecular patterns associated with ferroptosis in Parkinson's disease and its immune signature

Parkinson's disease is the second most common neurodegenerative disease in the world. We downloaded data on Parkinson's disease and Ferroptosis-related genes from the GEO and FerrDb databases. We used WCGAN and Random Forest algorithm to screen out five Parkinson's disease ferroptosis-related hub genes. Two genes were identified for the first time as possibly playing a role in Braak staging progression. Unsupervised clustering analysis based on hub genes yielded ferroptosis isoforms, and immune infiltration analysis indicated that these isoforms are associated with immune cells and may represent different immune patterns. FRHGs scores were obtained to quantify the level of ferroptosis modifications in each individual. In addition, differences in interleukin expression were found between the two ferroptosis subtypes. The biological functions involved in the hub gene are analyzed. The ceRNA regulatory network of hub genes was mapped. The disease classification diagnosis model and risk prediction model were also constructed by applying hub genes based on logistic regression. Multiple external datasets validated the hub gene and classification diagnostic model with some accuracy. This study explored hub genes associated with ferroptosis in Parkinson's disease and their molecular patterns and immune signatures to provide new ideas for finding new targets for intervention and predictive biomarkers.

A Dual GLP-1/GIP Receptor Agonist Is More Effective than Liraglutide in the A53T Mouse Model of Parkinson's Disease

Parkinson's disease (PD) is a complex syndrome with many elements, such as chronic inflammation, oxidative stress, mitochondrial dysfunction, loss of dopaminergic neurons, build-up of alpha-synuclein (α-syn) in cells, and energy depletion in neurons, that drive the disease. We and others have shown that treatment with mimetics of the growth factor glucagon-like peptide 1 (GLP-1) can normalize energy utilization, neuronal survival, and dopamine levels and reduce inflammation. Liraglutide is a GLP-1 analogue that recently showed protective effects in phase 2 clinical trials in PD patients and in Alzheimer disease patients. We have developed a novel dual GLP-1/GIP receptor agonist that can cross the blood-brain barrier and showed good protective effects in animal models of PD. Here, we test liraglutide against the dual GLP-1/GIP agonist DA5-CH (KP405) in the A53T tg mouse model of PD which expresses a human-mutated gene of α-synuclein. Drug treatment reduced impairments in three different motor tests, reduced levels of α-syn in the substantia nigra, reduced the inflammation response and proinflammatory cytokine levels in the substantia nigra and striatum, and normalized biomarker levels of autophagy and mitochondrial activities in A53T mice. DA5-CH was superior in almost all parameters measured and therefore may be a better drug treatment for PD than liraglutide.

Rapid degeneration of iPSC-derived motor neurons lacking Gdap1 engages a mitochondrial-sustained innate immune response

Charcot-Marie-Tooth disease is a chronic hereditary motor and sensory polyneuropathy targeting Schwann cells and/or motor neurons. Its multifactorial and polygenic origin portrays a complex clinical phenotype of the disease with a wide range of genetic inheritance patterns. The disease-associated gene GDAP1 encodes for a mitochondrial outer membrane protein. Mouse and insect models with mutations in Gdap1 have reproduced several traits of the human disease. However, the precise function in the cell types affected by the disease remains unknown. Here, we use induced-pluripotent stem cells derived from a Gdap1 knockout mouse model to better understand the molecular and cellular phenotypes of the disease caused by the loss-of-function of this gene. Gdap1-null motor neurons display a fragile cell phenotype prone to early degeneration showing (1) altered mitochondrial morphology, with an increase in the fragmentation of these organelles, (2) activation of autophagy and mitophagy, (3) abnormal metabolism, characterized by a downregulation of Hexokinase 2 and ATP5b proteins, (4) increased reactive oxygen species and elevated mitochondrial membrane potential, and (5) increased innate immune response and p38 MAP kinase activation. Our data reveals the existence of an underlying Redox-inflammatory axis fueled by altered mitochondrial metabolism in the absence of Gdap1. As this biochemical axis encompasses a wide variety of druggable targets, our results may have implications for developing therapies using combinatorial pharmacological approaches and improving therefore human welfare. A Redox-immune axis underlying motor neuron degeneration caused by the absence of Gdap1. Our results show that Gdap1^-/- motor neurons have a fragile cellular phenotype that is prone to degeneration. Gdap1^-/- iPSCs differentiated into motor neurons showed an altered metabolic state: decreased glycolysis and increased OXPHOS. These alterations may lead to hyperpolarization of mitochondria and increased ROS levels. Excessive amounts of ROS might be the cause of increased mitophagy, p38 activation and inflammation as a cellular response to oxidative stress. The p38 MAPK pathway and the immune response may, in turn, have feedback mechanisms, leading to the induction of apoptosis and senescence, respectively. CAC, citric acid cycle; ETC, electronic transport chain; Glc, glucose; Lac, lactate; Pyr, pyruvate.

Inhibitory Effects of Thermolysis Transformation Products of Rotenone on Nitric Oxide Production

Rotenone, isolated from Derris, Lonchocarpus, and Tephrosia from the family Fabaceae, has been shown to have a variety of biological properties and is used in various agricultural industries as a potent biopesticide. However, recent reports have demonstrated that rotenone has the potential to cause several adverse effects such as a neurodegenerative disease. This study aimed to induce thermolysis of the biopesticide rotenone and enhance the functionality of the degraded products. Rotenone (1) was degraded after autoclaving for 12 h, and the thermolytic reactants showed enhanced anti-inflammatory capacity against nitric oxide (NO) production. The structures of the newly modified products were spectroscopically determined. The thermal reaction products included various isoflavonoid derivatives 2-6, whose structures were characterized as being produced via chemical reactions in rotenone at the C-12 positions. Among the degraded products, (-)-tubaic acid (6) exhibited significantly improved anti-inflammatory effects compared to the original rotenone. Quantitative LC-MS analysis of the major thermolysis products generated in Derris extract containing rotenone was performed using isolate 2-5 purified from autoclaved rotenone. These results suggest that the thermal transformation of rotenone can improve the functionality of anti-inflammatory agents.

Machine learning study: from the toxicity studies to tetrahydrocannabinol effects on Parkinson's disease

Aim: Investigating molecules having toxicity and chemical similarity to find hit molecules. Methods: The machine learning (ML) model was developed to predict the arylhydrocarbon receptor (AHR) activity of anti-Parkinson's and US FDA-approved drugs. The ML algorithm was a support vector machine, and the dataset was Tox21. Results: The ML model predicted apomorphine in anti-Parkinson's drugs and 73 molecules in FDA-approved drugs as active. The authors were curious if there is any molecule like apomorphine in these 73 molecules. A fingerprint similarity analysis of these molecules was conducted and found tetrahydrocannabinol (THC). Molecular docking studies of THC for dopamine receptor 1 (affinity = -8.2 kcal/mol) were performed. Conclusion: THC may affect dopamine receptors directly and could be useful for Parkinson's disease.

DA5-CH and Semaglutide Protect against Neurodegeneration and Reduce α-Synuclein Levels in the 6-OHDA Parkinson's Disease Rat Model

Insulin desensitization has been observed in the brains of patients with Parkinson's disease (PD), which is a progressive neurodegenerative disorder for which there is no cure. Semaglutide is a novel long-actingglucagon-likepeptide-1 (GLP-1) receptor agonist that is on the market as a treatment for type 2 diabetes. It is in a phase II clinical trial in patients with PD. Two previous phase II trials in PD patients showed good effects with the older GLP-1 receptor agonists, exendin-4 and liraglutide. We have developed a dual GLP-1/GIP receptor agonist (DA5-CH) that can cross the blood-brain barrier (BBB) at a higher rate than semaglutide. We tested semaglutide and DA5-CH in the 6-OHDA-lesion rat model of PD. Treatment was semaglutide or DA5-CH (25 nmol/kg, i.p.) daily for 30 days postlesion. Both drugs reduced the apomorphine-induced rotational behavior and alleviated dopamine depletion and the inflammation response in the lesioned striatum as shown in reduced IL-1β and TNF-α levels, with DA5-CH being more effective. In addition, both drugs protected dopaminergic neurons and increased TH expression in the substantia nigra. Furthermore, the level of monomer and aggregated α-synuclein was reduced by the drugs, and insulin resistance as shown in reduced pIRS-1ser312 phosphorylation was also attenuated after drug treatment, with DA5-CH being more effective. Therefore, while semaglutide showed good effects in this PD model, DA5-CH was superior and may be a better therapeutic drug for neurodegenerative disorders such as PD than GLP-1 receptor agonists that do not easily cross the BBB.

Molecular and Cellular Interactions in Pathogenesis of Sporadic Parkinson Disease

An increasing number of the population all around the world suffer from age-associated neurodegenerative diseases including Parkinson’s disease (PD). This disorder presents different signs of genetic, epigenetic and environmental origin, and molecular, cellular and intracellular dysfunction. At the molecular level, α-synuclein (αSyn) was identified as the principal molecule constituting the Lewy bodies (LB). The gut microbiota participates in the pathogenesis of PD and may contribute to the loss of dopaminergic neurons through mitochondrial dysfunction. The most important pathogenetic link is an imbalance of Ca²⁺ ions, which is associated with redox imbalance in the cells and increased generation of reactive oxygen species (ROS). In this review, genetic, epigenetic and environmental factors that cause these disorders and their cause-and-effect relationships are considered. As a constituent of environmental factors, the example of organophosphates (OPs) is also reviewed. The role of endothelial damage in the pathogenesis of PD is discussed, and a ‘triple hit hypothesis’ is proposed as a modification of Braak’s dual hit one. In the absence of effective therapies for neurodegenerative diseases, more and more evidence is emerging about the positive impact of nutritional structure and healthy lifestyle on the state of blood vessels and the risk of developing these diseases.

The Innate and Adaptive Immune Cells in Alzheimer’s and Parkinson’s Diseases

Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common neurodegenerative disorders of the central nervous system (CNS). Increasing evidence supports the view that dysfunction of innate immune cells initiated by accumulated and misfolded proteins plays essential roles in the pathogenesis and progression of these diseases. The TLR family was found to be involved in the regulation of microglial function in the pathogenesis and progression of AD or PD, making it as double-edged sword in these diseases. Altered function of peripheral innate immune cells was found in AD and PD and thus contributed to the development and progression of AD and PD. Alteration of different subsets of T cells was found in the peripheral blood and CNS in AD and PD. The CNS-infiltrating T cells can exert both neuroprotective and neurotoxic effects in the pathogenesis and progression. Here, we review recent evidences for the roles of innate and adaptive immune cells in the pathogenesis and progression of AD and PD.

Modulation of Inflammatory Mediators and Microglial Activation Through Physical Exercise in Alzheimer's and Parkinson's Diseases

Neuroinflammation is an inflammatory process in the central nervous system (CNS), in addition to being one of the main features of Alzheimer's disease (AD) and Parkinson's disease (PD). Microglia are known for their immune functions and have multiple reactive phenotypes related to the types of stages involving neurodegenerative diseases. Depending on the state of activation of microglia in the CNS, it can be neuroprotective or neurotoxic. In this context, AD is a neurodegenerative and neuroinflammatory disease characterized by the deposition of beta-amyloid plaques, formation of fibrillar tangles of tau protein, and loss of neurons due to neurotoxic activation of microglia. However, PD is characterized by the loss of dopaminergic neurons in the substantia nigra and accumulation of alpha-synuclein in the cortical regions, spinal cord, and brain stem, which occurs by microglial activation, contributing to the neuroinflammatory process. In this aspect, the activation of microglia in both pathologies triggers high levels of inflammatory markers, such as interleukins, and causes the neuroinflammatory process of the diseases. Thus, physical exercise is pointed out as neuroprotective, as it can act to strengthen neurogenesis and reduce the inflammatory process. Therefore, the present review addresses the neuroprotective effect of microglia after different types of physical exercise protocols and evaluates the activity and effects of inflammatory and anti-inflammatory parameters and mechanisms of AD and PD. This review will discuss the anti-inflammatory effects of physical exercise through microglia activation with neuroprotective activity and the role of pro-and anti-inflammatory cytokines in AD and PD.

Establishing gene regulatory networks from Parkinson's disease risk loci

The latest meta-analysis of genome-wide association studies identified 90 independent variants across 78 genomic regions associated with Parkinson's disease, yet the mechanisms by which these variants influence the development of the disease remains largely elusive. To establish the functional gene regulatory networks associated with Parkinson's disease risk variants, we utilized an approach combining spatial (chromosomal conformation capture) and functional (expression quantitative trait loci) data. We identified 518 genes subject to regulation by 76 Parkinson's variants across 49 tissues, whicih encompass 36 peripheral and 13 CNS tissues. Notably, one-third of these genes were regulated via trans-acting mechanisms (distal; risk locus-gene separated by >1 Mb, or on different chromosomes). Of particular interest is the identification of a novel trans-expression quantitative trait loci-gene connection between rs10847864 and SYNJ1 in the adult brain cortex, highlighting a convergence between familial studies and Parkinson's disease genome-wide association studies loci for SYNJ1 (PARK20) for the first time. Furthermore, we identified 16 neurodevelopment-specific expression quantitative trait loci-gene regulatory connections within the foetal cortex, consistent with hypotheses suggesting a neurodevelopmental involvement in the pathogenesis of Parkinson's disease. Through utilizing Louvain clustering we extracted nine significant and highly intraconnected clusters within the entire gene regulatory network. The nine clusters are enriched for specific biological processes and pathways, some of which have not previously been associated with Parkinson's disease. Together, our results not only contribute to an overall understanding of the mechanisms and impact of specific combinations of Parkinson's disease variants, but also highlight the potential impact gene regulatory networks may have when elucidating aetiological subtypes of Parkinson's disease.

Ethnomedicinal plants used for the treatment of neurodegenerative diseases in Himachal Pradesh, India in Western Himalaya

ETHNOPHARMACOLOGICAL RELEVANCE

Medicinal plants are considered as a healthcare resource and widely used by rural people in their traditional medicine system for curing neurodegenerative diseases. Neurodegenerative diseases refer to incurable and debilitating conditions that result in progressive degeneration/death of nerve cells or neurons in the human brain. This review is mainly focused on the usage of different ethnomedicinal plants in the treatment of different neurodegenerative diseases in Himachal Pradesh. Study reveals total of 73 ethnomedicinal plants, which are used for treating different neurological disorders in different areas of Himachal Pradesh. The data is compiled from the different sources that described the detailed information of plants in tabular form and highlights the significance of different phytochemicals on neuroprotective function. The present study also provides the scientific data and clinical (in-vivo and in-vitro) studies in support of ethnomedicinal use.

AIM OF THE STUDY

This review aims to provide information of ethnomedicinal plants which are used for the treatment of neurodegenerative diseases in Himachal Pradesh.

MATERIALS AND METHODS

Information on the use of ethnomedicinal plants to treat various neurological disorders has been gathered from a variety of sources, including various types of literature, books, and relevant publications in Google Scholar, Research Gate, Science Direct, Scopus, and Pub Med, among others. The collected data is tabulated, including the botanical names of plants, mode of use and the disease for which it is used for curing, etc. RESULTS: There are 73 ethnomedicinal plants that are used to cure various neurological disorders, with the most plants being used to treat epilepsy problem in Himachal Pradesh.

CONCLUSION

Numerous phytochemicals and extracts from diverse plants were found to have a protective effect against neurodegenerative diseases. Antioxidant activity is known to exist in a variety of herbal plants. The most common bioactive antioxidant chemicals having their significant impacts include flavonoids, flavones, coumarins, lignans, isoflavones, catechins, anthocyanins, and isocatechins.

Comparison of cognitive performance between patients with Parkinson's disease and dystonia using an intraoperative recognition memory test

Neuroscientific studies on the function of the basal ganglia often examine the behavioral performance of patients with movement disorders, such as Parkinson’s disease (PD) and dystonia (DT), while simultaneously examining the underlying electrophysiological activity during deep brain stimulation surgery. Nevertheless, to date, there have been no studies comparing the cognitive performance of PD and DT patients during surgery. In this study, we assessed the memory function of PD and DT patients with the Montreal Cognitive Assessment (MoCA) and the Mini-Mental State Examination (MMSE). We also tested their cognitive performance during the surgery using a continuous recognition memory test. The results of the MoCA and MMSE failed to reveal significant differences between the PD and DT patients. Additionally, no significant difference was detected by the intraoperative memory test between the PD and DT patients. The intraoperative memory test scores were highly correlated with the MMSE scores and MoCA scores. Our data suggest that DT patients perform similarly to PD patients in cognitive tests during surgery, and intraoperative memory tests can be used as a quick memory assessment tool during surgery.

Myeloid cells in retinal and brain degeneration

Retinal inflammation underlies multiple prevalent ocular and neurological diseases. Similar inflammatory processes are observed in glaucomatous optic neuropathy, age-related macular degeneration, retinitis pigmentosa, posterior uveitis, Alzheimer's disease, and Parkinson's disease. In particular, human and animal studies have demonstrated the important role microglia/macrophages play in initiating and maintaining a pro-inflammatory environment in degenerative processes impacting vision. On the other hand, microglia have also been shown to have a protective role in multiple central nervous system diseases. Identifying the mechanisms underlying cell dysfunction and death is the first step toward developing novel therapeutics for these diseases impacting the central nervous system. In addition to reviewing recent key studies defining important mediators of retinal inflammation, with an emphasis on translational studies that bridge this research from bench to bedside, we also highlight a promising therapeutic class of medications, the glucagon-like peptide-1 receptor agonists. Finally, we propose areas where additional research is necessary to identify mechanisms that can be modulated to shift the balance from a neurotoxic to a neuroprotective retinal environment.

Gasdermin D in pyroptosis

Pyroptosis is the process of inflammatory cell death. The primary function of pyroptosis is to induce strong inflammatory responses that defend the host against microbe infection. Excessive pyroptosis, however, leads to several inflammatory diseases, including sepsis and autoimmune disorders. Pyroptosis can be canonical or noncanonical. Upon microbe infection, the canonical pathway responds to pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs), while the noncanonical pathway responds to intracellular lipopolysaccharides (LPS) of Gram-negative bacteria. The last step of pyroptosis requires the cleavage of gasdermin D (GsdmD) at D275 (numbering after human GSDMD) into N- and C-termini by caspase 1 in the canonical pathway and caspase 4/5/11 (caspase 4/5 in humans, caspase 11 in mice) in the noncanonical pathway. Upon cleavage, the N-terminus of GsdmD (GsdmD-N) forms a transmembrane pore that releases cytokines such as IL-1β and IL-18 and disturbs the regulation of ions and water, eventually resulting in strong inflammation and cell death. Since GsdmD is the effector of pyroptosis, promising inhibitors of GsdmD have been developed for inflammatory diseases. This review will focus on the roles of GsdmD during pyroptosis and in diseases.

Lactobacillus paracasei ameliorates cognitive impairment in high-fat induced obese mice via insulin signaling and neuroinflammation pathways

Long-term consumption of a high-fat diet (HFD) can cause glucose and lipid metabolism disorders, damage the brain and nervous system and result in cognitive impairment. The objective of this study was to investigate the preventative effects of Lactobacillus paracasei (Jlus66, a probiotic extracted from cheese in Northeast China) on cognitive impairment associated with HFD. The water maze was used to compare memory changes in mice fed HFD with or without Jlus66. Hippocampal tissue morphology was examined using H&E staining. The expression of neurotrophic factors BDNF, PSD95 and SNAP25, insulin resistance related proteins IRS-1, AKT and GSK3β, and inflammatory related proteins JNK and p38 were detected using western blotting. The results showed that Jlus66 significantly increased the expression of BDNF, PSD95 and SNAP25 (p < 0.01, respectively), increased expression of p-AKT (p < 0.05), p-IRS-1Y612 and p-GSK3β (p < 0.01, respectively), and reduced the expression of p-IRS-1S307, p-JNK and p-p38 (p < 0.05) compared with the HFD group. We conclude that Jlus66 can ameliorate cognitive impairment via insulin signaling and neuroinflammation pathways.

The GLP-1/GIP dual-receptor agonist DA5-CH inhibits the NF-κB inflammatory pathway in the MPTP mouse model of Parkinson's disease more effectively than the GLP-1 single-receptor agonist NLY01

The GLP-1 receptor agonist exendin-4 has recently shown good effects in a phase II clinical trial in Parkinson's disease (PD) patients. Here, a comparison of the new GLP-1/GIP dual receptor agonist DA5-CH and NLY01, a 40 kDa pegylated form of exendin-4, on motor impairments and reducing inflammation in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) PD mouse model is provided. The drug groups received either DA5-CH or NLY01 (25 nmol/kg) i.p. after daily MPTP intraperitoneal injection. Both drugs showed improvements in motor activity, open field experiments, rotarod tests, and gait analysis, but DA5-CH was more potent. Tyrosine hydroxylase expression in dopaminergic neurons was much reduced by MPTP and improved by DA5-CH, while NLY01 showed weak effects. When analyzing levels of α-synuclein (α-Syn), DA5-CH reduced levels effectively while NLY01 had no effect. When measuring the levels of the inflammation markers Toll-like receptor 4 (TLR4), specific markers of microglia activation (Iba-1), the marker of astrocyte activation glial fibrillary acidic protein (GFAP), nuclear factor-κB (NF-κB), tumor necrosis factor (TNF-α), and transforming growth factor β1 (TGF-β1), DA5-CH was very effective in reducing the chronic inflammation response, while NLY01 did not show significant effects. Levels of key growth factors such as Glial cell-derived neurotrophic factor (GDNF) and Brain-derived neurotrophic factor (BDNF) were much reduced by MPTP, and DA5-CH was able to normalize levels in the brain, while NLY01 showed little effect. The levels of pro-inflammatory cytokines (IL-6 and IL-Iβ) were much reduced by DA5-CH, too, while NLY01 showed no effect. In a separate experiment, we tested the ability of the two drugs to cross the blood-brain barrier. After injecting fluorescin-labelled peptides peripherally, the fluorescence in brain tissue was measured. It was found that the pegylated NLY01 peptide did not cross the BBB in meaningful quantities while exendin-4 and the dual agonist DA5-CH did. The results show that DA5-CH shows promise as a therapeutic drug for PD.

Coriandrum sativum attenuates microglia mediated neuroinflammation and MPTP-induced behavioral and oxidative changes in Parkinson's disease mouse model

Coriandrum sativum Linn. (family: Umbelliferae; C. sativum), is a potential herb widely used as a spice and traditional medicine. In the present work, the effects of C. sativum fruit extract (CSE), against lipopolysaccharide (LPS)-stimulated BV-2 microglia-mediated neuroinflammation in vitro and 1-methyl-4 phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP)-induced Parkinson's disease (PD) animal model in vivo was investigated. LPS-stimulated increase in nitric oxide (NO), inducible NO synthase, cyclooxygenase-2, interleukin-6 and tumor necrosis factor-alpha were significantly (p < 0.05 ~ p < 0.001) inhibited by CSE (25, 50 and 100 μg/mL) in BV-2 microglial cells. Further, CSE inhibited the LPS-induced nuclear factor of kappa-beta activation and IκB-α phosphorylation in BV-2 microglia. In vivo studies, CSE (100, 200 and 300 mg/kg) ameliorated the MPTP (25 mg/kg, i.p.)-induced changes in locomotor, cognitive and behavior functions evaluated by rotarod, passive avoidance and open field test significantly (p < 0.05 ~ p < 0.001). The MPTP-induced changes in brain oxidative enzyme levels such as superoxide dismutase, catalase, and lipid peroxidation were significantly (p < 0.01 and p < 0.001 at 200 and 300 mg/kg, respectively) restored with CSE treatment. High-performance thin-layer chromatography fingerprinting analysis of CSE exhibited several distinctive peaks with quercetin and kaempferol-3O-glucoside as identifiable compounds. In conclusion, our study indicated that CSE attenuated neuroinflammatory processes in LPS-stimulated microglia in vitro and restored the MPTP-induced behavioral deficits and brain oxidative enzyme status in vivo proving its therapeutic potential in the treatment of neuroinflammatory and oxidative stress-mediated neurodegeneration seen in PD.

Allogeneic Bone Marrow-Derived Mesenchymal Stem Cell Safety in Idiopathic Parkinson's Disease

BACKGROUND

Neuroinflammation plays a key role in PD pathogenesis, and allogeneic bone marrow-derived mesenchymal stem cells can be used as an immunomodulatory therapy.

OBJECTIVE

The objective of this study was to prove the safety and tolerability of intravenous allogeneic bone marrow-derived mesenchymal stem cells in PD patients.

METHODS

This was a 12-month single-center open-label dose-escalation phase 1 study of 20 subjects with mild/moderate PD assigned to a single intravenous infusion of 1 of 4 doses: 1, 3, 6, or 10 × 10⁶ allogeneic bone marrow-derived mesenchymal stem cells/kg, evaluated 3, 12, 24, and 52 weeks postinfusion. Primary outcome safety measures included transfusion reaction, study-related adverse events, and immunogenic responses. Secondary outcomes included impact on peripheral markers, PD progression, and changes in brain perfusion.

RESULTS

There were no serious adverse reactions related to the infusion and no responses to donor-specific human leukocyte antigens. Most common treatment-emergent adverse events were dyskinesias (20%, n = 4) with 1 emergent and 3 exacerbations; and hypertension (20%, n = 4) with 3 transient episodes and 1 requiring medical intervention. One possibly related serious adverse event occurred in a patient with a 4-year history of lymphocytosis who developed asymptomatic chronic lymphocytic leukemia. Peripheral inflammation markers appear to be reduced at 52 weeks in the highest dose including, tumor necrosis factor-α (P < 0.05), chemokine (C-C motif) ligand 22 (P < 0.05), whereas brain-derived neurotrophic factor (P < 0.05) increased. The highest dose seems to have demonstrated the most significant effect at 52 weeks, reducing the OFF state UPDRS motor, -14.4 (P < 0.01), and total, -20.8 (P < 0.05), scores.

CONCLUSION

A single intravenous infusion of allogeneic bone marrow-derived mesenchymal stem cells at doses of 1, 3, 6, or 10 × 10⁶ allogeneic bone marrow-derived mesenchymal stem cells/kg is safe, well tolerated, and not immunogenic in mild/moderate PD patients. © 2021 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Alpha-Synuclein in the Regulation of Brain Endothelial and Perivascular Cells: Gaps and Future Perspectives

Misfolded proteins, inflammation, and vascular alterations are common pathological hallmarks of neurodegenerative diseases. Alpha-synuclein is a small synaptic protein that was identified as a major component of Lewy bodies and Lewy neurites in the brain of patients affected by Parkinson's disease (PD), Lewy body dementia (LBD), and other synucleinopathies. It is mainly involved in the regulation of synaptic vesicle trafficking but can also control mitochondrial/endoplasmic reticulum (ER) homeostasis, lysosome/phagosome function, and cytoskeleton organization. Recent evidence supports that the pathological forms of α-synuclein can also reduce the release of vasoactive and inflammatory mediators from endothelial cells (ECs) and modulates the expression of tight junction (TJ) proteins important for maintaining the blood-brain barrier (BBB). This hints that α-synuclein deposition can affect BBB integrity. Border associated macrophages (BAMs) are brain resident macrophages found in association with the vasculature (PVMs), meninges (MAMs), and choroid plexus (CPMs). Recent findings indicate that these cells play distinct roles in stroke and neurodegenerative disorders. Although many studies have addressed how α-synuclein may modulate microglia, its effect on BAMs has been scarcely investigated. This review aims at summarizing the main findings supporting how α-synuclein can affect ECs and/or BAMs function as well as their interplay and effect on other cells in the brain perivascular environment in physiological and pathological conditions. Gaps of knowledge and new perspectives on how this protein can contribute to neurodegeneration by inducing BBB homeostatic changes in different neurological conditions are highlighted.

Early low-dose ghrelin intervention via miniosmotic pumps could protect against the progressive dopaminergic neuron loss in Parkinson's disease mice

Ghrelin has been identified as a multifunctional peptide that has a potential application for treating Parkinson's disease (PD). The objective of this study was to assess the effects of subcutaneous administration of low-dose ghrelin via miniosmotic pumps on PD progression. The decreased levels of total and active ghrelin in plasma were rescued by ghrelin administration in PD mice. Interestingly, ghrelin did not affect weight gain in wild-type mice but improved weight loss in PD mice. We observed the attenuation of dopaminergic neuron loss in substantia nigra and a low level of dopamine content in the striatum in PD mice with ghrelin treatment. Ghrelin administration could improve the microenvironment of dopaminergic neurons by inhibiting microglial proliferation and proinflammatory cytokine expression and could enhance cell survival by upregulating Bcl-2/Bax ratio and superoxide dismutase1 protein level in the substantia nigra of PD mice. Subcutaneous administration of low-dose ghrelin could prevent the onset of the progression of PD and also provide a possible method for ghrelin application to cure PD.

Lactobacillus paracasei ameliorates cognitive impairment in high-fat induced obese mice via insulin signaling and neuroinflammation pathways

Long-term consumption of a high-fat diet (HFD) can cause glucose and lipid metabolism disorders, damage the brain and nervous system and result in cognitive impairment.

2-Hydroxy-4-Methylbenzoic Anhydride Inhibits Neuroinflammation in Cellular and Experimental Animal Models of Parkinson's Disease

Microglia-mediated neuroinflammation is one of the key mechanisms involved in acute brain injury and chronic neurodegeneration. This study investigated the inhibitory effects of 2-hydroxy-4-methylbenzoic anhydride (HMA), a novel synthetic derivative of HTB (3-hydroxy-4-trifluoromethylbenzoic acid) on neuroinflammation and underlying mechanisms in activated microglia in vitro and an in vivo mouse model of Parkinson’s disease (PD). In vitro studies revealed that HMA significantly inhibited lipopolysaccharide (LPS)-stimulated excessive release of nitric oxide (NO) in a concentration dependent manner. In addition, HMA significantly suppressed both inducible NO synthase and cyclooxygenase-2 (COX-2) at the mRNA and protein levels in LPS-stimulated BV-2 microglia cells. Moreover, HMA significantly inhibited the proinflammatory cytokines such as interleukin (IL)-1beta, IL-6, and tumor necrosis factor-alpha in LPS-stimulated BV-2 microglial cells. Furthermore, mechanistic studies ensured that the potent anti-neuroinflammatory effects of HMA (0.1, 1.0, and 10 μM) were mediated by phosphorylation of nuclear factor of kappa light polypeptide gene enhancer in B-cells inhibitor, alpha (IκBα) in LPS-stimulated BV-2 cells. In vivo evaluations revealed that intraperitoneal administration of potent neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, 20 mg/kg, four times a 1 day) in mice resulted in activation of microglia in the brain in association with severe behavioral deficits as assessed using a pole test. However, prevention of microglial activation and attenuation of Parkinson’s disease (PD)-like behavioral changes was obtained by oral administration of HMA (30 mg/kg) for 14 days. Considering the overall results, our study showed that HMA exhibited strong anti-neuroinflammatory effects at lower concentrations than its parent compound. Further work is warranted in other animal and genetic models of PD for evaluating the efficacy of HMA to develop a potential therapeutic agent in the treatment of microglia-mediated neuroinflammatory disorders, including PD.

Fibrinogen and risk of dementia: A systematic review and meta-analysis

BACKGROUND

The aim of this meta-analysis is to evaluate the association of fibrinogen with risk of dementia and its subtypes.

METHODS

Embase, Pubmed and Web of Science were retrieved systematically up to February 2019. Standard mean difference (SMD) with 95 % confidence intervals was estimated using random-effects models.

RESULTS

Sixteen studies involving 3,649 participants were summarized. Patients with all-cause dementia exhibited higher fibrinogen levels than those in non-dementia controls (SMD = 0.90 [0.43;1.36] p < 0.01). Further subgroup analysis revealed a positive association of fibrinogen with vascular dementia (VaD) (SMD = 1.11 [0.45;1.78] p < 0.01) rather than Alzheimer's disease (AD) (SMD = 0.01 [-0.17;0.19]) p = 0.92) and Parkinson's disease dementia (PDD) (SMD = 0.35 [-0.23;0.93] p = 0.24). This correlation was significant in Europeans (SMD = 0.92 [0.34;1.49] p < 0.01), but probably not in Asian based populations (SMD = 1.04 [-0.09;2.17] p = 0.07), and gradually declined with advancing age (60 ≤ age < 70: SMD = 1.22 [0.38;2.06] p < 0.01; 70 ≤ age < 80: SMD = 0.29 [0.04;0.53] p = 0.02; age ≥ 80: SMD = 0.01 [-0.12;0.15] p = 0.84).

CONCLUSIONS

Plasma fibrinogen is a potential risk factor for all-cause dementia and VaD under the age of 80, and is more obvious in cohorts with people of European descent.

Chronic Systemic Inflammation Exacerbates Neurotoxicity in a Parkinson's Disease Model

Systemic inflammation is a crucial factor for microglial activation and neuroinflammation in neurodegeneration. This work is aimed at assessing whether previous exposure to systemic inflammation potentiates neurotoxic damage by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and how chronic systemic inflammation participates in the physiopathological mechanisms of Parkinson's disease. Two different models of systemic inflammation were employed to explore this hypothesis: a single administration of lipopolysaccharide (sLPS; 5 mg/kg) and chronic exposure to low doses (mLPS; 100 μg/kg twice a week for three months). After three months, both groups were challenged with MPTP. With the sLPS administration, Iba1 staining increased in the striatum and substantia nigra, and the cell viability lowered in the striatum of these mice. mLPS alone had more impact on the proinflammatory profile of the brain, steadily increasing TNFα levels, activating microglia, reducing BDNF, cell viability, and dopamine levels, leading to a damage profile similar to the MPTP model per se. Interestingly, mLPS increased MAO-B activity possibly conferring susceptibility to MPTP damage. mLPS, along with MPTP administration, exacerbated the neurotoxic effect. This effect seemed to be coordinated by microglia since minocycline administration prevented brain TNFα increase. Coadministration of sLPS with MPTP only facilitated damage induced by MPTP without significant change in the inflammatory profile. These results indicate that chronic systemic inflammation increased susceptibility to MPTP toxic effect and is an adequate model for studying the impact of systemic inflammation in Parkinson's disease.

The therapeutic role of cannabinoid receptors and its agonists or antagonists in Parkinson's disease

Parkinson's disease (PD) is a neurodegenerative disease and its characteristic is the progressive degeneration of dopaminergic neurons within the substantia nigra (SN) of the midbrain. There is hardly any clinically proven efficient therapeutics for its cure in several recent preclinical advances proposed to treat PD. Recent studies have found that the endocannabinoid signaling system in particular the comprised two receptors, CB1 and CB2 receptors, has a significant regulatory function in basal ganglia and is involved in the pathogenesis of PD. Therefore, adding new insights into the biochemical interactions between cannabinoids and other signaling pathways may help develop new pharmacological strategies. Factors of the endocannabinoid system (ECS) are abundantly expressed in the neural circuits of basal ganglia, where they interact interactively with glutamatergic, γ-aminobutyric acid-ergic (GABAergic), and dopaminergic signaling systems. Although preclinical studies on PD are promising, the use of cannabinoids at the clinical level has not been thoroughly studied. In this review, we evaluated the available evidence and reviewed the involvement of ECS in etiologies, symptoms and treatments related to PD. Since CB1 and CB2 receptors are the two main receptors of endocannabinoids, we primarily put the focus on the therapeutic role of CB1 and CB2 receptors in PD. We will try to determine future research clues that will help understand the potential therapeutic benefits of the ECS in the treatment of PD, aiming to open up new strategies and ideas for the treatment of PD.

Effects of DCM Leaf Extract of Gnidia glauca (Fresen) on Locomotor Activity, Anxiety, and Exploration-Like Behaviors in High-Fat Diet-Induced Obese Rats

Obesity is the main component of metabolic syndromes involving distinct etiologies that target different underlying behavioral and physiological functions within the brain structures and neuronal circuits. An alteration in the neuronal circuitry stemming from abdominal or central obesity stimulates a cascade of changes in neurochemical signaling that directly or indirectly mediate spontaneously emitted behaviors such as locomotor activity patterns, anxiety, and exploration. Pharmacological agents available for the treatment of neurologic disorders have been associated with limited potency and intolerable adverse effects. These have necessitated the upsurge in the utilization of herbal prescriptions due to their affordability and easy accessibility and are firmly embedded within wider belief systems of many people. Gnidia glauca has been used in the management of many ailments including obesity and associated symptomatic complications. However, its upsurge in use has not been accompanied by empirical determination of these folkloric claims. The present study, therefore, is aimed at determining the modulatory effects of dichloromethane leaf extract of Gnidia glauca on locomotor activity, exploration, and anxiety-like behaviors in high-fat diet-induced obese rats in an open-field arena. Obesity was experimentally induced by feeding the rats with prepared high-fat diet and water ad libitum for 6 weeks. The in vivo antiobesity effects were determined by oral administration of G. glauca at dosage levels of 200, 250, and 300 mg/kg body weight in high-fat diet-induced obese rats from the 6^th to 12^th week. Phytochemical analysis was done using gas chromatography linked to mass spectroscopy. Results indicated that Gnidia glauca showed anxiolytic effects and significantly increased spontaneous locomotor activity and exploration-like behaviors in HFD-induced obese rats. The plant extract also contained phytocompounds that have been associated with amelioration of the main neurodegenerative mediators, viz., inflammation and oxidative stress. These findings provide “qualified leads” for the synthesis of new alternative therapeutic agents for the management of neurologic disorders. However, there is a need to conduct toxicity studies of Gnidia glauca to establish its safety profiles.

Utilization of the CRISPR-Cas9 Gene Editing System to Dissect Neuroinflammatory and Neuropharmacological Mechanisms in Parkinson's Disease

Chronic and debilitating neurodegenerative diseases, such as Parkinson's disease (PD), impose an immense medical, emotional, and economic burden on patients and society. Due to a complex interaction between genetic and environmental risk factors, the etiology of PD remains elusive. However, the cumulative evidence emerging from clinical and experimental research over the last several decades has identified mitochondrial dysfunction, oxidative stress, neuroinflammation, and dysregulated protein degradation as the main drivers of PD neurodegeneration. The genome-editing system CRISPR (clustered regularly interspaced short palindromic repeats) has recently transformed the field of biotechnology and biomedical discovery and is poised to accelerate neurodegenerative disease research. It has been leveraged to generate PD animal models, such as Parkin, DJ-1, and PINK1 triple knockout miniature pigs. CRISPR has also allowed the deeper understanding of various PD gene interactions, as well as the identification of novel apoptotic pathways associated with neurodegenerative processes in PD. Furthermore, its application has been used to dissect neuroinflammatory pathways involved in PD pathogenesis, such as the PKCδ signaling pathway, as well as the roles of novel compensatory or protective pathways, such as Prokineticin-2 signaling. This review aims to highlight the historical milestones in the evolution of this technology and attempts to illustrate its transformative potential in unraveling disease mechanisms as well as in the development of innovative treatment strategies for PD. Graphical Abstract.

Role of Catalase in Oxidative Stress- and Age-Associated Degenerative Diseases

Reactive species produced in the cell during normal cellular metabolism can chemically react with cellular biomolecules such as nucleic acids, proteins, and lipids, thereby causing their oxidative modifications leading to alterations in their compositions and potential damage to their cellular activities. Fortunately, cells have evolved several antioxidant defense mechanisms (as metabolites, vitamins, and enzymes) to neutralize or mitigate the harmful effect of reactive species and/or their byproducts. Any perturbation in the balance in the level of antioxidants and the reactive species results in a physiological condition called “oxidative stress.” A catalase is one of the crucial antioxidant enzymes that mitigates oxidative stress to a considerable extent by destroying cellular hydrogen peroxide to produce water and oxygen. Deficiency or malfunction of catalase is postulated to be related to the pathogenesis of many age-associated degenerative diseases like diabetes mellitus, hypertension, anemia, vitiligo, Alzheimer's disease, Parkinson's disease, bipolar disorder, cancer, and schizophrenia. Therefore, efforts are being undertaken in many laboratories to explore its use as a potential drug for the treatment of such diseases. This paper describes the direct and indirect involvement of deficiency and/or modification of catalase in the pathogenesis of some important diseases such as diabetes mellitus, Alzheimer's disease, Parkinson's disease, vitiligo, and acatalasemia. Details on the efforts exploring the potential treatment of these diseases using a catalase as a protein therapeutic agent have also been described.

The multiple roles of exosomes in Parkinson's disease: an overview

The extracellular vesicles (EVs) represent a relatively new field of research in neurodegenerative disease and they are thought to be one of the ways that neurodegenerative pathologies, such as Parkinson's Disease (PD), spread in the brain. EVs are membrane vesicles released from cells into the extracellular space and they are produced by all cells of the nervous tissue. The classification of the vesicle subtypes comprises exosomes, microvesicles/microparticles, apoptotic bodies. EVs change in number and content in response to environmental conditions and may function as shuttles for the delivery of cargo between cells. Recent data suggest that exosomes secreted by both activated microglia and neurons play an important role in α-synuclein (α-syn) spreading and increase of neuroinflammation, thus exacerbating neuronal dysfunction and disease progression. α-syn is a presynaptic protein secreted by neurons in small amounts, and it is the main component of Lewy bodies, one of the histopathological features of PD. Several factors have shown to induce and/or modulate α-syn structure and oligomerization in vitro. Under pathological conditions, progressive accumulation of α-syn and the formation of oligomers have been proposed to play a critical role in the pathogenesis of PD. This review gives an overview about the multiple roles of exosomes in PD, despite their role in the progression of neurodegeneration, exosomes could represent a specific drug delivery tool for a difficult target such as the brain, which poses an obstacle to most drugs and they could also represent new biomarkers to track the progression of PD.

Akt Phosphorylates NQO1 and Triggers its Degradation, Abolishing Its Antioxidative Activities in Parkinson's Disease

The oxidative metabolism of dopamine and consequent oxidative stress are implicated in dopaminergic neuronal loss, mediating the pathogenesis of Parkinson's disease (PD). The inducible detoxifying antioxidative enzyme Quinone oxidoreductase (NQO1) (NAD(P)H: quinone oxidoreductase 1), neuroprotective to counteract reactive oxidative species, is most prominent in the active stage of the disease and virtually absent at the end stage of the disease. However, the molecular mechanism dictating NQO1 expression oscillation remains unclear. Here we show that Akt phosphorylates NQO1 at T128 residues and triggers its polyubiquitination and proteasomal degradation, abrogating its antioxidative effects in PD. Akt binds NQO1 in a phosphorylation-dependent manner. Interestingly, Akt, but not PINK1, provokes NQO1 phosphorylation and polyubiquitination with Parkin as an E3 ligase. Unphosphorylatable NQO1 mutant displays more robust neuroprotective activity than WT NQO1 in suppressing reactive oxidative species and against MPTP-induced dopaminergic cell death, rescuing the motor disorders in both α-synuclein transgenic transgenic male and female mice elicited by the neurotoxin. Thus, our findings demonstrate that blockade of Akt-mediated NQO1 degradation may ameliorate PD pathogenesis.SIGNIFICANCE STATEMENT Dopaminergic neurodegeneration in Parkinson's disease (PD) is associated with the imbalance of oxidative metabolism of dopamine. Quinone oxidoreductase (NQO1), a potent antioxidant system, its expression levels are prominently increased in the early and intermediate stages of PD and disappeared in the end-stage PD. The molecular modification behavior of NQO1 after it is upregulated by oxidative stress in the early stage of PD, however, remains unclear. This study shows that Akt binds and phosphorylates NQO1 at T128 residue and promotes its ubiquitination and degradation, and Parkin acts as an E3 ligase in this process, which affects the antioxidant capacity of NQO1. This finding provides a novel molecular mechanism for NQO1 oscillation in PD pathogenesis.

Risk of Parkinson disease in Sjögren syndrome administered ineffective immunosuppressant therapies: A nationwide population-based study

To determine the incidence and risk of Parkinson disease (PD) in patients with Sjögren syndrome (SS) according to a nationwide population-based database.In total, 12,640 patients in the SS cohort and 50,560 in the non-SS cohort were enrolled from Taiwan's National Health Insurance Research Database from 2000 to 2010. We used the Cox multivariable proportional hazards model to determine the risk factors for PD in the SS cohort.We observed an increased incidence of PD in patients with SS, with a crude hazard ratio (HR) of 1.40 and an adjusted HR (aHR) of 1.23. The cumulative incidence of PD was 1.95% higher in the SS cohort than in the non-SS cohort. The SS cohort had an elevated HR under medication use, namely cevimeline and pilocarpine (crude HR, 1.28), hydroxychloroquine (crude HR, 1.43; aHR, 1.46), and methylprednisolone (crude HR, 2.21; aHR, 1.49). Patients receiving other non-hydroxychloroquine immunosuppressant therapies had a lower risk (aHR, 0.86) of PD. Furthermore, patients with SS aged 20 to 49 years had a 1.93-fold higher risk of PD than did those without SS (aHR, 1.93). The risk of PD was higher (aHR, 2.20) in patients with SS without comorbidities than in those with comorbidities. The aHR of PD significantly increased when the follow-up period exceeded 9 years (aHR, 1.93).We determined an increased risk of PD in patients with SS. Further investigation is warranted to determine the possible underlying mechanisms and the potential role of non-hydroxychloroquine immunosuppressants in ameliorating PD.

Inflammation, Infectious Triggers, and Parkinson's Disease

Parkinson's disease is a neurodegenerative disorder characterized by progressive loss of dopaminergic neurons of the substantia nigra pars compacta with a reduction of dopamine concentration in the striatum. The complex interaction between genetic and environmental factors seems to play a role in determining susceptibility to PD and may explain the heterogeneity observed in clinical presentations. The exact etiology is not yet clear, but different possible causes have been identified. Inflammation has been increasingly studied as part of the pathophysiology of neurodegenerative diseases, corroborating the hypothesis that the immune system may be the nexus between environmental and genetic factors, and the abnormal immune function can lead to disease. In this review we report the different aspects of inflammation and immune system in Parkinson's disease, with particular interest in the possible role played by immune dysfunctions in PD, with focus on autoimmunity and processes involving infectious agents as a trigger and alpha-synuclein protein (α-syn).

Theranostic applications of nanoparticles in neurodegenerative disorders

The preeminent treatments for neurodegenerative disease are often unavailable due to the poor accessibility of therapeutic drugs. Moreover, the blood–brain barrier (BBB) effectively blocks the transfer of cells, particles and large molecules, ie, drugs, across the brain. The most important challenge in the treatment of neurodegenerative diseases is the development of targeted drug delivery system. Theranostic strategies are known to combine therapeutic and diagnostic capabilities together. The aim of this review was to record the response to treatment and thereby improve drug safety. Nanotechnology offers a platform for designing and developing theranostic agents that can be used as an efficient nano-carrier system. This is achieved by the manipulation of some of the properties of nanoparticles (NPs), thereby enabling the attachment of suitable drugs onto their surface. The results provide revolutionary treatments by stimulation and thus interaction with targeted sites to promote physiological response with minimum side effects. This review is a brief discussion of the administration of drugs across the brain and the advantages of using NPs as an effective theranostic platform in the treatment of Alzheimer’s, Parkinson’s, epilepsy and Huntington’s disease.

In vivo quantification of glial activation in minipigs overexpressing human α-synuclein

Parkinson's disease is characterized by a progressive loss of substantia nigra (SN) dopaminergic neurons and the formation of Lewy bodies containing accumulated alpha-synuclein (α-syn). The pathology of Parkinson's disease is associated with neuroinflammatory microglial activation, which may contribute to the ongoing neurodegeneration. This study investigates the in vivo microglial and dopaminergic response to overexpression of α-syn. We used positron emission tomography (PET) and the 18 kDa translocator protein radioligand, [¹¹ C](R)PK11195, to image brain microglial activation and (+)-α-[¹¹ C]dihydrotetrabenazine ([¹¹ C]DTBZ), to measure vesicular monoamine transporter 2 (VMAT2) availability in Göttingen minipigs following injection with recombinant adeno-associated virus (rAAV) vectors expressing either mutant A53T α-syn or green fluorescent protein (GFP) into the SN (4 rAAV-α-syn, 4 rAAV-GFP, 5 non-injected control minipigs). We performed motor symptom assessment and immunohistochemical examination of tyrosine hydroxylase (TH) and transgene expression. Expression of GFP and α-syn was observed at the SN injection site and in the striatum. We observed no motor symptoms or changes in striatal [¹¹ C]DTBZ binding potential in vivo or striatal or SN TH staining in vitro between the groups. The mean [¹¹ C](R)PK11195 total volume of distribution was significantly higher in the basal ganglia and cortical areas of the α-syn group than the control animals. We conclude that mutant α-syn expression in the SN resulted in microglial activation in multiple sub- and cortical regions, while it did not affect TH stains or VMAT2 availability. Our data suggest that microglial activation constitutes an early response to accumulation of α-syn in the absence of dopamine neuron degeneration.

No effects without causes: the Iron Dysregulation and Dormant Microbes hypothesis for chronic, inflammatory diseases

Since the successful conquest of many acute, communicable (infectious) diseases through the use of vaccines and antibiotics, the currently most prevalent diseases are chronic and progressive in nature, and are all accompanied by inflammation. These diseases include neurodegenerative (e.g. Alzheimer's, Parkinson's), vascular (e.g. atherosclerosis, pre-eclampsia, type 2 diabetes) and autoimmune (e.g. rheumatoid arthritis and multiple sclerosis) diseases that may appear to have little in common. In fact they all share significant features, in particular chronic inflammation and its attendant inflammatory cytokines. Such effects do not happen without underlying and initially 'external' causes, and it is of interest to seek these causes. Taking a systems approach, we argue that these causes include (i) stress-induced iron dysregulation, and (ii) its ability to awaken dormant, non-replicating microbes with which the host has become infected. Other external causes may be dietary. Such microbes are capable of shedding small, but functionally significant amounts of highly inflammagenic molecules such as lipopolysaccharide and lipoteichoic acid. Sequelae include significant coagulopathies, not least the recently discovered amyloidogenic clotting of blood, leading to cell death and the release of further inflammagens. The extensive evidence discussed here implies, as was found with ulcers, that almost all chronic, infectious diseases do in fact harbour a microbial component. What differs is simply the microbes and the anatomical location from and at which they exert damage. This analysis offers novel avenues for diagnosis and treatment.

Association between Open-Angle Glaucoma and the Risks of Alzheimer's and Parkinson's Diseases in South Korea: A 10-year Nationwide Cohort Study

We aimed to investigate the risks of Alzheimer’s (AD) and Parkinson’s disease (PD) in the 10 years following diagnosis of open-angle glaucoma (OAG) using a nationwide cohort. This propensity score-matched retrospective cohort study included 1,025,340 subjects from the Korean National Health Insurance Service National Sample Cohort database. The OAG group (n = 1,469) included patients who were initially diagnosed with OAG between 2004 and 2007, and the subjects in the comparison group were matched in a 1:5 ratio using propensity scores. Cox regression analyses were performed to investigate the risks of developing AD or PD. The diagnosis of OAG was significantly associated with an increased incidence of AD (hazard ratio [HR] = 1.403, 95% confidence interval [CI] 1.180–1.669, p < 0.001), but not PD (HR = 0.995, 95% CI 0.620–1.595, p = 0.983) after adjusting for possible confounding factors. In subgroup analyses, participants with OAG aged ≥65 years were more likely to develop AD compared with those aged <65 years, and female OAG patients had a greater risk of developing AD than males. Patients diagnosed with OAG have a higher risk of developing AD, but not PD, and the risk differed according to age and sex.

Tolerogenic bone marrow-derived dendritic cells induce neuroprotective regulatory T cells in a model of Parkinson's disease

BACKGROUND

Administration of granulocyte-macrophage colony-stimulating factor (GM-CSF) increases regulatory T cell (Treg) number and function with control of neuroinflammation and neuronal protection in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) model of Parkinson's disease (PD). Recently, we demonstrated in an early phase 1 clinical trial that GM-CSF also improves motor skills in PD patients. However, the mechanisms of Treg induction and its effects on neuroprotective responses remain unknown. As GM-CSF induces tolerogenic dendritic cells (DCs) that in turn convert conventional T cells to Tregs, the pathways for DC induction of Tregs were assessed.

METHODS

Following differentiation, bone marrow-derived dendritic cells (BMDCs) were cultured in media or GM-CSF with or without post-culture stimulation with nitrated α-synuclein (N-α-Syn). Expression of cell surface co-stimulatory molecules and proinflammatory cytokines, and induction of Tregs were evaluated. The neuroprotective capacity of tolerogenic BMDCs was assessed by adoptive transfer to MPTP-intoxicated mice. The extent of neuroinflammation and numbers of surviving dopaminergic neurons were assessed in relation to Treg numbers.

RESULTS

Co-culture of differentiated BMDCs with conventional T cells led to Treg induction. Stimulation of BMDCs with N-α-Syn increased expression of co-stimulatory molecules and proinflammatory cytokines, with modest increases in Treg numbers. In contrast, continued culture of BMDCs with GM-CSF modestly altered expression of co-stimulatory molecules and proinflammatory cytokines and chemokines, but decreased Treg induction. Continued culture in GM-CSF and combined stimulation with N-α-Syn reduced Treg induction to the lowest levels. Adoptive transfer of tolerogenic BMDCs to MPTP-intoxicated mice increased splenic Tregs, attenuated neuroinflammatory responses, and protected nigrostriatal dopaminergic neurons.

CONCLUSIONS

GM-CSF acts broadly to differentiate DCs and affect immune transformation from effector to regulatory immune responses. DCs skew such immune responses by increasing Treg numbers and activities that serve to attenuate proinflammatory responses and augment neuroprotection.

Neuroprotective potential of crocin against malathion-induced motor deficit and neurochemical alterations in rats

In several epidemiological studies, an association between pesticide exposure and the incidence of Parkinson's disease (PD) has been reported. Increasing evidence showed that oxidative stress plays an important role in the pathogenesis of PD. The present study investigated the preventive effect of crocin, saffron active components, on malathion (an organophosphate pesticide (OP))-induced Parkinson-like behaviors in rat. Rats were divided into eight groups: control (normal saline), malathion (100 mg/kg/day, i.p), crocin (10, 20, or 40 mg/kg/day, i.p) plus malathion, levodopa (10 mg/kg/day, i.p) plus malathion, crocin (40 mg/kg/day, i.p), and PEG (vehicle of levodopa) groups. Treatments were continued for 28 days. The neurobehavioral tests which include open field, rotarod and catalepsy were performed on day 28. The activity of acetylcholinesterase (AChE) in serum, the levels of malondialdehyde (MDA), reduced glutathione (GSH), TNF-α, and IL-6 in striatum at the end of treatments were evaluated. Results showed that malathion induced neurobehavioral impairments together with elevation of MDA, TNF-α and IL-6 levels, reduction of GSH, and AChE activity. Crocin (10, 20, and 40 mg/kg) improved neurobehavioral impairments induced by malathion but not AChE activity. Crocin (10, 20, and 40 mg/kg) or levodopa plus malathion decreased MDA and increased GSH. Also crocin (10 mg/kg) decreased TNF-α and IL-6 levels in striatum. In summary, subchronic malathion exposure induced Parkinson-like behavior in rat. Crocin exhibited protective effects against malathion-induced Parkinson-like behavior through reducing lipid peroxidation, improvement of motor deficit and anti-inflammatory effects.

Purple sweet potato color attenuates high fat-induced neuroinflammation in mouse brain by inhibiting MAPK and NF-κB activation

Purple sweet potato color (PSPC) is a natural anthocyanin pigment that is derived from purple sweet potato storage roots. PSPC possesses a variety of biological activities, including antioxidant, anti‑inflammatory and neuroprotective effects; however, the detailed effects of PSPC on high‑fat diet (HFD)‑induced neuroinflammation remain to be determined. The aim of the present study was to investigate whether PSPC has a protective role in HFD‑associated neuroinflammation in the mouse brain and to provide novel insight into the mechanisms of the action. C57BL 6J mice were maintained on a normal diet (10 kcal% fat), a HFD (60 kcal% fat), a HFD with PSPC (700 mg/kg/day) or PSPC alone, which was administrated over 20 weeks. Open field and step‑through tests were used to evaluate the effects of HFD and PSPC on mouse behavior and memory function. Western blotting and ELISA analyses were used to assess the expression of inflammatory cytokines and the activation of mitogen‑activated protein kinase and nuclear factor‑κB (NF‑κB). The results demonstrated that PSPC treatment was able to significantly improve the HFD‑induced impairment of mouse behavior and memory function, and suppressed the increase in body weight, fat content, hyperlipemia and the level of endotoxin. PSPC treatment also markedly decreased the expression of cyclooxygenase‑2, inducible nitric oxide synthase, tumor necrosis factor‑α, interleukin (IL)‑1β and IL‑6, and increased the level of IL‑10 in the HFD‑treated mouse brain. In addition, PSPC inhibited the HFD‑induced phosphorylation of extracellular signal‑regulated kinase (ERK), c‑Jun N‑terminal kinase (JNK) and p38, and the activation of NF‑κB. These findings indicated that PSPC treatment may alleviate HFD‑induced neuroinflammation in the mouse brain by inhibiting ERK, JNK, p38 and NF-κB activation.

Achyranthes bidentata polypeptide protects dopaminergic neurons from apoptosis in Parkinson's disease models both in vitro and in vivo

BACKGROUND AND PURPOSE

Parkinson's disease (PD) is a neurodegenerative disorder closely associated with dopaminergic neuron loss. It is well documented that Achyranthes bidentata polypeptides (ABPP) are potent neuroprotective agents in several kinds of neurons. Therefore, we proposed that ABPP might play a beneficial role against PD by protecting dopaminergic neurons from apoptosis.

EXPERIMENTAL APPROACH

SH-SY5Y cells and primary rat dopaminergic neurons were pretreated with ABPP fraction k (ABPPk), a purified fraction of ABPP, and then the cells were exposed to 1-methyl-4-phenylpyridinium iodide (MPP⁺ ) to induce apoptosis. Cell viability, LDH activity, a Tunel assay and protein levels of Bcl-2 and Bax were analysed. In an in vivo PD model induced by MPTP, ABPPk was intranasally delivered to mice. Behavioural tests, immunohistochemistry, immunostaining, Nissl staining, qRT-PCR and Western blot were employed to evaluate the potential effects of ABPPk on PD in mice.

KEY RESULTS

The application of ABPPk markedly enhanced the viability of SH-SY5Y cells and primary dopaminergic neurons treated with neurotoxic agent MPP⁺ . In an in vivo MPTP-induced PD model, ABPPk significantly improved behavioural performances and prevented tyrosine hydroxylase loss in the substantia nigra pars compacta and striatum. Furthermore, we showed that MPTP-induced astrocyte and microglia activation were largely attenuated by ABPPk, leading to low levels of neuroinflammation and a downregulation of the apoptotic signalling pathway.

CONCLUSION AND IMPLICATIONS

Taken together, our data show that ABPPk protects dopaminergic neurons from apoptosis, suggesting that ABPPk might be an effective intervention for treating the neuron loss associated with disorders such as PD.

Vanishing cerebral vasculitis in a patient with Lewy pathology

Immune-mediated mechanisms are involved in the pathogenesis of both cerebral vasculitis and Parkinson's disease (PD, brainstem-predominant Lewy pathology), but the presentation of cerebral vasculitis with comorbid Lewy pathology has not yet been reported. Here we present a case of pathologically confirmed vasculitis in a 73-year-old male patient whose postmortem examination revealed Lewy pathology diagnostic of PD. This case study suggests a comorbidity of cerebral vasculitis and Lewy pathology, as well as potential pathogenic interactions between these two disorders with immune-mediated mechanisms.

Alterations in the Interplay between Neurons, Astrocytes and Microglia in the Rat Dentate Gyrus in Experimental Models of Neurodegeneration

The hippocampus is negatively affected by aging and neurodegenerative diseases leading to impaired learning and memory abilities. A diverse series of progressive modifications in the intercellular communication among neurons, astrocytes and microglia occur in the hippocampus during aging or inflammation. A detailed understanding of the neurobiological modifications that contribute to hippocampal dysfunction may reveal new targets for therapeutic intervention. The current study focussed on the interplay between neurons and astroglia in the Granule Layer (GL) and the Polymorphic Layer (PL) of the Dentate Gyrus (DG) of adult, aged and LPS-treated rats. In GL and PL of aged and LPS-treated rats, astrocytes were less numerous than in adult rats. In GL of LPS-treated rats, astrocytes acquired morphological features of reactive astrocytes, such as longer branches than was observed in adult rats. Total and activated microglia increased in the aged and LPS-treated rats, as compared to adult rats. In the GL of aged and LPS-treated rats many neurons were apoptotic. Neurons decreased significantly in GL and PL of aged but not in rats treated with LPS. In PL of aged and LPS-treated rats many damaged neurons were embraced by microglia cells and were infiltrated by branches of astrocyte, which appeared to be bisecting the cell body, forming triads. Reactive microglia had a scavenging activity of dying neurons, as shown by the presence of neuronal debris within their cytoplasm. The levels of the chemokine fractalkine (CX3CL1) increased in hippocampal homogenates of aged rats and rats treated with LPS, and CX3CL1 immunoreactivity colocalized with activated microglia cells. Here we demonstrated that in the DG of aged and LPS-treated rats, astrocytes and microglia cooperate and participate in phagocytosis/phagoptosis of apoptotic granular neurons. The differential expression/activation of astroglia and the alteration of their intercommunication may be responsible for the different susceptibility of the DG in comparison to the CA1 and CA3 hippocampal areas to neurodegeneration during aging and inflammation.

The Role of Microglia in Retinal Neurodegeneration: Alzheimer's Disease, Parkinson, and Glaucoma

Microglia, the immunocompetent cells of the central nervous system (CNS), act as neuropathology sensors and are neuroprotective under physiological conditions. Microglia react to injury and degeneration with immune-phenotypic and morphological changes, proliferation, migration, and inflammatory cytokine production. An uncontrolled microglial response secondary to sustained CNS damage can put neuronal survival at risk due to excessive inflammation. A neuroinflammatory response is considered among the etiological factors of the major aged-related neurodegenerative diseases of the CNS, and microglial cells are key players in these neurodegenerative lesions. The retina is an extension of the brain and therefore the inflammatory response in the brain can occur in the retina. The brain and retina are affected in several neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), and glaucoma. AD is an age-related neurodegeneration of the CNS characterized by neuronal and synaptic loss in the cerebral cortex, resulting in cognitive deficit and dementia. The extracellular deposits of beta-amyloid (Aβ) and intraneuronal accumulations of hyperphosphorylated tau protein (pTau) are the hallmarks of this disease. These deposits are also found in the retina and optic nerve. PD is a neurodegenerative locomotor disorder with the progressive loss of dopaminergic neurons in the substantia nigra. This is accompanied by Lewy body inclusion composed of α-synuclein (α-syn) aggregates. PD also involves retinal dopaminergic cell degeneration. Glaucoma is a multifactorial neurodegenerative disease of the optic nerve, characterized by retinal ganglion cell loss. In this pathology, deposition of Aβ, synuclein, and pTau has also been detected in retina. These neurodegenerative diseases share a common pathogenic mechanism, the neuroinflammation, in which microglia play an important role. Microglial activation has been reported in AD, PD, and glaucoma in relation to protein aggregates and degenerated neurons. The activated microglia can release pro-inflammatory cytokines which can aggravate and propagate neuroinflammation, thereby degenerating neurons and impairing brain as well as retinal function. The aim of the present review is to describe the contribution in retina to microglial-mediated neuroinflammation in AD, PD, and glaucomatous neurodegeneration.