Lipid and immune abnormalities causing age-dependent neurodegeneration and Parkinson's disease

Biogeography of intestinal mucus-associated microbiome: Depletion of genus Pseudomonas is associated with depressive-like behaviors in female cynomolgus macaques

INTRODUCTION

Depression is a debilitating and poorly understood mental disorder. There is an urgency to explore new potential biological mechanisms of depression and the gut microbiota is a promising research area.

OBJECTIVES

Our study was aim to understand regional heterogeneity and potential molecular mechanisms underlying depression induced by dysbiosis of mucus-associated microbiota.

METHODS

Here, we only selected female macaques because they are more likely to form a natural social hierarchy in a harem-like environment. Because high-ranking macaques rarely displayed depressive-like behaviors, we selected seven monkeys from high-ranking individuals as control group (HC) and the same number of low-ranking ones as depressive-like group (DL), which displayed significant depressive-like behaviors. Then, we collected mucus from the duodenum, jejunum, ileum, cecum and colon of DL and HC monkeys for shotgun metagenomic sequencing, to profile the biogeography of mucus-associated microbiota along duodenum to colon.

RESULTS

Compared with HC, DL macaques displayed noticeable depressive-like behaviors such as longer duration of huddle and sit alone behaviors (negative emotion behaviors), and fewer duration of locomotion, amicable and ingestion activities (positive emotion behaviors). Moreover, the alpha diversity index (Chao) could predict aforementioned depressive-like behaviors along duodenum to colon. Further, we identified that genus Pseudomonas was consistently decreased in DL group throughout the entire intestinal tract except for the jejunum. Specifically, there were 10, 18 and 28 decreased Pseudomonas spp. identified in ileum, cecum and colon, respectively. Moreover, a bacterial module mainly composed of Pseudomonas spp. was positively associated with three positive emotion behaviors. Functionally, Pseudomonaswas mainly involved in microbiota derived lipid metabolisms such as PPAR signaling pathway, cholesterol metabolism, and fat digestion and absorption.

CONCLUSION

Different regions of intestinal mucus-associated microbiota revealed that depletion of genus Pseudomonas is associated with depressive-like behaviors in female macaques, which might induce depressive phenotypes through regulating lipid metabolism.

Multiplatform Lipid Analysis of the Brain of Aging Mice by Mass Spectrometry

Lipids are critical to brain structure and function, accounting for approximately 50% of its dry weight. However, the impact of aging on brain lipids remains poorly characterized. To address this, here we applied three complementary mass spectrometry techniques: multiple reaction monitoring (MRM) profiling, untargeted liquid chromatography tandem mass spectrometry (LC-MS/MS), and desorption electrospray ionization-MS imaging (DESI-MSI). We used brains from mice of three age groups: adult (3-4 months), middle-aged (10 months), and old (19-21 months). Phospholipids such as phosphatidylcholine, phosphatidylethanolamine, and phosphatidylglycerol were more abundant, while phosphatidylinositol and phosphatidylserine were reduced in old mice compared to adults or middle-aged mice. Key lipids such as polyunsaturated fatty acids, including DHA, AA, HexCer, SHexCer, and SM, were among the most abundant lipids in aged brains. DESI-MSI revealed spatial lipid distribution patterns consistent with findings from MRM profiling and LC-MS/MS. Integration of lipidomic data with the recently published proteomics data from the same tissues highlighted changes in proteins and phosphorylation levels of several proteins associated with Cer, HexCer, FA, PI, SM, and SHexCer metabolism, aligning with the multiplatform lipid surveillance. These findings shed insight into age-dependent brain lipid changes and their potential contribution to age-related cognitive decline.

Effects of different exercises on improving gait performance in patients with Parkinson's disease: a systematic review and network meta-analysis

Objective

Gait disorder represents a characteristic symptom of Parkinson's disease (PD), and exercise has been established as an effective intervention for gait management in PD. However, the relative efficacy of various exercise types in improving gait among PD patients remains unclear. This study aimed to compare the effectiveness of different movement-based interventions in enhancing gait for individuals with PD through a network meta-analysis.

Methods

A comprehensive search was conducted across multiple databases, including PubMed, Cochrane Library, Embase, Web of Science, and CNKI. The methodological quality of included studies was evaluated using the Cochrane Bias risk tool. Data was extracted from these studies to compare the efficacy of 29 distinct exercise interventions on gait performance in patients with PD.

Results

The analysis encompassed 68 randomized controlled trials (RCTs), involving a total of 3,114 participants. The results of the network meta-analysis showed that DE is higher than CON (SMD, 2.11; 95% CI 1.07 to 3.15), WE (SMD, 2.16; 95% CI 0.90 to 3.43), HE (SMD, 2.19; 95% CI 0.95 to 3.44), OE (SMD, 2.66; 95% CI 1.16 to 4.16), TR (SMD, 2.62; 95% CI 1.45 to 3.79) to better improve Gait velocity in patients with Parkinson's disease. DE is superior to CON (SMD, 2.08; 95% CI 0.04 to 4.13) in improving Step length. FAE is superior to CON (SMD, 1.01; 95% CI 0.04 to 1.98), BDJ (SMD, 1.20; 95% CI 0.15 to 2.25), RAGT (SMD, 1.29; 95% CI 0.07 to 2.52), DE (SMD, 1.57; 95% CI 0.36 to 2.77), TR (SMD, 1.62; 95% CI 0.48 to 2.76), OE (1.76, 95% CI 0.57 to 2.94) in improving Gait velocity. RAGT is superior to CT (MD, 2.02; 95% CI 0.41 to 3.63), TR (MD, 2.51; 95% CI 1.17 to 3.84), AE (MD, 2.66; 95% CI 0.45 to 4.88), BDJ (MD, 2.77; 95% CI 0.93 to 4.61), CON (MD, 2.83; 95% CI 1.30 to 4.36), DTT (MD, 12.84; 95% CI 10.05 to 15.63) in improving 6MWT.

Conclusion

Our study found that DE improved gait speed and step length in patients with Parkinson's disease better than other forms of exercise. FAE and RAGT were more effective than other exercises in improving step length and 6MWT in patients with Parkinson's disease.

Cell type transcriptomics reveal shared genetic mechanisms in Alzheimer's and Parkinson's disease

Historically, Alzheimer's disease (AD) and Parkinson's disease (PD) have been investigated as two distinct disorders of the brain. However, a few similarities in neuropathology and clinical symptoms have been documented over the years. Traditional single gene-centric genetic studies, including GWAS and differential gene expression analyses, have struggled to unravel the molecular links between AD and PD. To address this, we tailor a pattern-learning framework to analyze synchronous gene co-expression at sub-cell-type resolution. Utilizing recently published single-nucleus AD (70,634 nuclei) and PD (340,902 nuclei) datasets from postmortem human brains, we systematically extract and juxtapose disease-critical gene modules. Our findings reveal extensive molecular similarities between AD and PD gene cliques. In neurons, disrupted cytoskeletal dynamics and mitochondrial stress highlight convergence in key processes; glial modules share roles in T-cell activation, myelin synthesis, and synapse pruning. This multi-module sub-cell-type approach offers insights into the molecular basis of shared neuropathology in AD and PD.

Biomarkers in Ataxia-Telangiectasia: a Systematic Review

Ataxia-Telangiectasia (A-T) is a very rare multisystem disease of DNA repair, associated with progressive disabling neurological symptoms, respiratory failure, immunodeficiency and cancer predisposition, leading to premature death. There are no curative treatments available for A-T but clinical trials have begun. A major limiting factor in effectively evaluating therapies for A-T is the lack of suitable outcome measures and biomarkers. We have performed a systematic review to collect the information currently available on biomarkers for A-T both in patients and preclinical studies. We have identified 56 reports discussing potential A-T biomarkers in both pre-clinical models and patients. These studies report on diagnostic biomarkers but prognostic biomarkers and responsive markers of clinical status are currently lacking. Some biomarkers of neurodegeneration in A-T show promise, including non-invasive neuroimaging biomarkers. Some biomarkers of oxidative stress and responsive markers to radiotherapy and steroid treatment have potential value in clinical trials. The formation of the A-T biomarker working group with international experts is an important step forward to facilitate the sharing of materials, data and expertise with the common goal of finding effective biomarkers for A-T.

FABP5 regulates ROS-NLRP3 inflammasome in glutamate-induced retinal excitotoxic glaucomatous model

Fatty acid binding proteins (FABPs) are a class of small molecular mass intracellular lipid chaperone proteins that bind to hydrophobic ligands, such as long-chain fatty acids. FABP5 expression was significantly upregulated in the N-methyl-d-aspartic acid (NMDA) model, the microbead-induced chronic glaucoma model, and the DBA/2J mice. Previous studies have demonstrated that FABP5 can mediate mitochondrial dysfunction and oxidative stress in ischemic neurons, but the role of FABP5 in oxidative stress and cell death in retina NMDA injury models is unclear. In this study, we found that FABP5 is significantly altered in a model of glutamate excitotoxicity and is regulated by Stat3. Inhibition of FABP5 alleviated oxidative stress imbalance and activation of NLRP3 inflammasome, reduced the release of inflammatory factors, and ultimately attenuated glutamate excitotoxicity-induced retinal ganglion cell loss. Meanwhile, caspase1 inhibitors could alleviate the retinal ganglion cell loss induced by glutamate excitotoxicity. In conclusion, FABP5 inhibition protects retina ganglion cells from excitotoxic damage by suppressing the ROS-NLRP3 inflammasome pathway. FABP5 maybe a promising new target for glaucoma diagnosis and treatment.

Selective diagnostics of Amyotrophic Lateral Sclerosis, Alzheimer's and Parkinson's Diseases with machine learning and miRNA

The diagnosis of neurological diseases can be expensive, invasive, and inaccurate, as it is often difficult to distinguish between different types of diseases with similar motor symptoms. However, the dysregulation of miRNAs can be used to create a robust machine-learning model for a reliable diagnosis of neurological diseases. We used miRNA sequence descriptors and gene target data to create machine-learning models that can be used as diagnostic tools. The top-performing machine-learning models, trained on filtered miRNA datasets for Amyotrophic Lateral Sclerosis, Alzheimer's and Parkinson's Diseases of this research yielded 94, 97, and 96, percent accuracies, respectively. Analysis of dysregulated miRNA in neurological diseases elucidated novel biomarkers that could be used to diagnose and distinguish between the diseases. Machine-learning models developed using sequence and gene target descriptors of miRNA biomarkers can achieve favorable accuracies for disease classification and attain a robust discerning capability of neurological diseases.

JZL-184 Alleviate Neurological Impairment through Regulation of Mitochondrial Transfer and Lipid Droplet Accumulation after Cardiac Arrest

Astrocytes are abundant glial cells in the central nervous system (CNS) that play important roles in brain injury following cardiac arrest (CA). Following brain ischemia, astrocytes trigger endogenous neuroprotective mechanisms, such as fatty acid transport. Lipid droplets (LDs) are cellular structures involved in neutral lipid storage and play essential roles in many biological processes. However, whether lipid droplet metabolism is related to the neurological prognosis after CA remains unclear. JZL-184 is a selective irreversible inhibitor of monoacylglycerol lipase (MAGL), and previous investigations revealed that JZL-184 confers neuroprotection in the brain following stroke. However, further investigations are warranted to explore the effect and mechanism of JZL-184 after CA. Here, we reveal that JZL-184 is neuroprotective after cardiac arrest, as it alleviates astroglial activation by upregulating the expression of transforming growth factor beta 1 (TGF-β1), promotes the transfer of mitochondria from astrocytes to neurons in the astrocyte‒neuron coculture system, and reduces lipid droplet accumulation in neurons. Mechanistically, this protective effect depends on the downstream genes DUSP4 and Rab27b. This study provides additional insights into strategies for inhibiting neurological impairment and suggests a potential therapeutic target after cardiac arrest.

Exploring the causal effects of serum lipids and lipidomes on lewy body dementia: a Mendelian randomization study

Background

Lewy body dementia (LBD) is a neurodegenerative disorder characterized by the accumulation of Lewy bodies, which primarily composed of misfolded alpha-synuclein (αS). The development of LBD and APOE4 subtypes is thought to be associated with disorders of lipid metabolism. In this study, we investigated the causal relationship between serum lipids, liposomes and LBD using a two-sample Mendelian randomization (TSMR) method.

Methods

A TSMR analysis of genome-wide association study (GWAS) data for 8 serum lipids, 179 lipidomes components, LBD and its subtypes was performed, using inverse variance weighted as the primary outcome. To ensure robustness, the sensitivity analyses including MR Pleiotropy RESidual Sum and Outlier, Cochran's test, leave-one-out method and funnel plots were performed.

Results

In this study, we found that low-density lipoprotein cholesterol (LDL-C) (OR=1.45, 95% CI=1.19-1.77, P<0.001) and remnant cholesterol (RC) (OR=2.64, 95% CI=1.64-4.28, P<0.001) had significant positive causal effects on LBD, and RC also had a positive effect on LBD in carriers of the APOE4 gene. The results of lipidome analysis showed that phosphatidylcholine (PC) (O-16:0_20:4) levels (OR=0.86, 95% CI=0.75-0.98, P=0.02) and PC (O-18:1_20:4) levels (OR=0.76, 95% CI=0.65-0.89, P <0.001) had negative causal effects on LBD, whereas phosphatidylinositol (PI) (18:1_20:4) levels had a positive causal effect on LBD (OR=1.19, 95% CI=1.02-1.39, P=0.03). For LBD with APOE4 carriers, high levels of PC (16:1_18:0) and PC (O-18:2_18:1) had a significant positive effect, while high levels of PC (O-16:1_18:0), phosphatidylethanolamine (PE) (O-18:2_18:1), sphingomyelin (SM) (d38:2), and triacylglycerol (TAG) (56:5) significantly reduced the risk. No heterogeneity and horizontal pleiotropy were observed in sensitivity analysis.

Conclusion

Elevated LDL-C and RC levels are significant risk factors for LBD, with RC also impacting APOE4-carrying LBD. Glycerophospholipids play a crucial role in the pathogenesis of LBD, but the specific components that play a role differ from those with the APOE4 carries. These findings highlight the importance of lipid metabolism in LBD and APOE4 subtypes.

Lysosomal dysfunction in α-synuclein pathology: molecular mechanisms and therapeutic strategies

In orchestrating cell signaling, facilitating plasma membrane repair, supervising protein secretion, managing waste elimination, and regulating energy consumption, lysosomes are indispensable guardians that play a crucial role in preserving intracellular homeostasis. Neurons are terminally differentiated post-mitotic cells. Neuronal function and waste elimination depend on normal lysosomal function. Converging data suggest that lysosomal dysfunction is a critical event in the etiology of Parkinson's disease (PD). Mutations in Glucosylceramidase Beta 1 (GBA1) and leucine-rich repeat kinase 2 (LRRK2) confer an increased risk for the development of parkinsonism. Furthermore, lysosomal dysfunction has been observed in the affected neurons of sporadic PD (sPD) patients. Given that lysosomal hydrolases actively contribute to the breakdown of impaired organelles and misfolded proteins, any compromise in lysosomal integrity could incite abnormal accumulation of proteins, including α-synuclein, the major component of Lewy bodies in PD. Clinical observations have shown that lysosomal protein levels in cerebrospinal fluid may serve as potential biomarkers for PD diagnosis and as signs of lysosomal dysfunction. In this review, we summarize the current evidence regarding lysosomal dysfunction in PD and discuss the intimate relationship between lysosomal dysfunction and pathological α-synuclein. In addition, we discuss therapeutic strategies that target lysosomes to treat PD.

Soluble LRP-1 in Parkinson's disease: clues for paradoxical effects

Background: Low density lipoprotein receptor-related protein-1 (LRP-1) is highly expressed in the central nervous system and plays a role in neurodegenerative disorders. The available data on this subject-matter seem to support the presence of a correlation between LRP-1 levels and abnormal aggregation of a plurality of proteins, including tau, amyloid, and α‑synuclein. Understanding the molecular mechanisms underlying Parkinson's disease (PD) is critical for development of new therapies.

Aim: To investigate serum soluble LRP-1 (sLRP-1) concentrations in patients with PD and explored their potential role as a biomarker in diagnosis and prognosis of disease.

Methods: Based on well-defined inclusion and exclusion criteria, we have included 133 PD patients and 45 healthy controls. The clinical severity was assessed using Hoehn Yahr and Unified PD Rating Scale (UPDRS). Following a fasting period, venous blood samples were taken, and centrifuged. Serum samples were stored until analysis. sLRP-1 was measured by ELISA assay.

Results: The median of serum sLRP-1 levels was higher in PD patients compared to that in healthy controls, but without reaching a statistical significance. There was a positive, but statistically insignificant, correlation between sLRP-1 levels and duration of disease. sLRP-1 levels had a significant correlation with UPDRS Parts I and IV. Patients with hypertension showed lower levels of sLRP-1.

Conclusion: The present study suggests that serum sLRP-1 concentrations are associated with the factors influencing prognosis of PD and disease severity. Further studies are needed to definitively determine whether or not sLRP-1 can be utilized as a diagnostic and prognostic biomarker for PD.

Effect of consumption of sheep and cow milk on rat brain fatty acid and phospholipid composition

The effect of sheep milk and cow milk on the lipid composition of rat brain was investigated in two feeding experiments of 28-days duration. Total lipids of the rat brain were extracted using ethanol-hexane, and the fatty acids and phospholipid contents analysed using gas chromatography with flame ionization detection (GC-FID) and phosphorus-31 nuclear magnetic resonance (31P NMR). Furthermore, freeze-dried pooled samples were analysed using attenuated total reflectance Fourier Transform Infrared and Fourier Transform Raman Spectroscopy and analysed with multivariate methods. A significantly (P < 0.05) higher C18:2 content was found in the cow milk group compared with sheep milk-treated groups in Study one. In Study two, a significantly (P < 0.05) lower C16:0 content was present in the sheep milk-treated group compared to the control low Ca/P group. No significant (P > 0.05) differences were observed in the spectroscopy analyses. It is concluded that sheep and cow milks fed to rats for 28-days had a low effect on the brain lipidome.

Upstream lipid and metabolic systems are potential causes of Alzheimer's disease, Parkinson's disease and dementias

Brain health requires circuits, cells and molecular pathways to adapt when challenged and to promptly reset once the challenge has resolved. Neurodegeneration occurs when adaptability becomes confined, causing challenges to overwhelm neural circuitry. Studies of rare and common neurodegenerative diseases suggest that the accumulation of lipids can compromise circuit adaptability. Using microglia as an example, we review data that suggest increased lipid concentrations cause dysfunctional inflammatory responses to immune challenges, leading to Alzheimer's disease, Parkinson's disease and dementia. We highlight current approaches to treat lipid metabolic and clearance pathways and identify knowledge gaps towards restoring adaptive homeostasis in individuals who are at-risk of losing cognition.

Effect of robot-assisted gait training on motor dysfunction in Parkinson's patients:A systematic review and meta-analysis

BACKGROUND

Robot-assisted gait training (RAGT) has been reported to treat motor dysfunction in patients with Parkinson's disease (PD) in the last few years. However, the benefits of RAGT for treating motor dysfunction in PD are still unclear.

OBJECTIVES

To investigate the efficacy of RAGT for motor dysfunction in PD patients.

METHODS

We searched PubMed, Web of Science, Cochrane Library, Embase, CNKI, Wanfang, Chinese Biomedical Literature Database (CBM), and Chinese VIP Database for randomized controlled trials investigating RAGT to improve motor dysfunction in PD from the databases' inception dates until September 1, 2022. The following outcome indexes were employed to evaluate motor dysfunction: the Berg Balance Scale (BBS), Activities-specific Balance Confidence Scale (ABC), 10-Meter Walk Test gait speed (10-MWT), gait speed, stride length, cadence Unified Parkinson Disease Rating Scale Part III (UPDRS III), 6-Minute Walk Test (6MWT), and the Timed Up and Go test (TUG). The meta-analysis was performed using the proper randomeffect model or fixed-effect model to evaluate the difference in efficacy between the RAGT and the control groups. The Cochrane Risk of Bias Tool was used for the included studies and Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) was used to interpret the certainty of the results.

RESULTS

The results consisted of 17 studies comprising a total of 670 participants. Six hundred and seven PD patients with motor dysfunction were included: 335 in the RAGT group and 335 in the control group. This meta-analysis results established that when compared with the control group, robot-assisted gait training improved the BBS results of PD patients (MD: 2.80, 95%CI: 2.11-3.49, P< 0.00001), ABC score (MD: 7.30, 95%CI: 5.08-9.52, P< 0.00001), 10-MWT (MD: 0.06, 95%CI: 0.03-0.10, P= 0.0009), gait speed (MD: 3.67, 95%CI: 2.58-4.76, P< 0.00001), stride length (MD: 5.53, 95%CI: 3.64-7.42, P< 0.00001), cadence (MD: 4.52, 95%CI: 0.94-8.10, P= 0.01), UPDRS III (MD: -2.16, 95%CI: -2.48--1.83, P< 0.00001), 6MWT (MD: 13.87, 95%CI: 11.92-15.82, P< 0.00001). However, RAGT did not significantly improve the TUG test result of patients with PD (MD =-0.56, 95% CI: -1.12-0.00, P= 0.05). No safety concerns or adverse reactions among robot-assisted gait training patients were observed.

CONCLUSION

Even though RAGT can improve balance function, walking function, and gait performance and has demonstrated positive results in several studies, there is currently insufficient compelling evidence to suggest that it can improve all aspects of lower motor function.

Effect of PLA2G6 and SMPD1 Variants on the Lipid Metabolism in the Cerebrospinal Fluid of Patients with Parkinson's Disease: A Non-targeted Lipidomics Study

INTRODUCTION

Sleep patterns are more frequently interrupted in patients with Parkinson's disease (PD), and it is still unclear whether genetic factors are involved in PD-related sleep disorders. In this study, we hypothesize that PD-associated genetic risk affects lipid metabolism, which in turn contributes to different types of sleep disorders.

METHODS

We used a non-targeted lipidomics to explore the lipid composition of cerebrospinal fluid (CSF) exosomes derived from patients with PD carrying phospholipase A2 Group VI (PLA2G6) and sphingomyelin phosphodiesterase 1 (SMPD1) mutations.

RESULTS

PLA2G6 mutations (c.1966C > G, Leu656Val; c.2077C > G, Leu693Val; c.1791delC, His597fx69) significantly increase the exosomal content of glycerophospholipids and lysophospholipids, specifically phosphatidylcholine (PC) and lysophosphatidylcholine (LPC). Exosome surface presence of melatomin receptor 1A (MTNR1A) was detectable only in patients with PLA2G6 mutations. We have further shown that, in patients with PD carrying PLA2G6 mutations, sleep latency was significantly longer compared to those carrying WT PLA2G6, and we speculate that functional PLA2G6 mutations lead to structural changes and lipid deregulation of exosomes, which in turn alters exosomal cargo and affects PD-related sleep disorders. In SMPD1, G508R variant-carrying patients with PD abundance of sphingomyelins was significantly higher and had significantly shorter rapid eye movement sleep.

CONCLUSIONS

Our study demonstrated that the disturbed composition and function of CSF-derived exosome lipidome during the pathological stage of PD may affect different types of sleep disorder in PD.

Loss of Lipid Carrier ApoE Exacerbates Brain Glial and Inflammatory Responses after Lysosomal GBA1 Inhibition

Tightly regulated and highly adaptive lipid metabolic and transport pathways are critical to maintaining brain cellular lipid homeostasis and responding to lipid and inflammatory stress to preserve brain function and health. Deficits in the lipid handling genes APOE and GBA1 are the most significant genetic risk factors for Lewy body dementia and related dementia syndromes. Parkinson's disease patients who carry both APOE4 and GBA1 variants have accelerated cognitive decline compared to single variant carriers. To investigate functional interactions between brain ApoE and GBA1, in vivo GBA1 inhibition was tested in WT versus ApoE-deficient mice. The experiments demonstrated glycolipid stress caused by GBA1 inhibition in WT mice induced ApoE expression in several brain regions associated with movement and dementia disorders. The absence of ApoE in ApoE-KO mice amplified complement C1q elevations, reactive microgliosis and astrocytosis after glycolipid stress. Mechanistically, GBA1 inhibition triggered increases in cell surface and intracellular lipid transporters ABCA1 and NPC1, respectively. Interestingly, the absence of NPC1 in mice also triggered elevations of brain ApoE levels. These new data show that brain ApoE, GBA1 and NPC1 functions are interconnected in vivo, and that the removal or reduction of ApoE would likely be detrimental to brain function. These results provide important insights into brain ApoE adaptive responses to increased lipid loads.

27-Hydroxycholesterol Drives the Spread of α-Synuclein Pathology in Parkinson's Disease

BACKGROUND

The accumulation and aggregation of α-synuclein (α-Syn) are characteristic of Parkinson's disease (PD). Epidemiological evidence indicates that hyperlipidemia is associated with an increased risk of PD. The levels of 27-hydroxycholesterol (27-OHC), a cholesterol oxidation derivative, are increased in the brain and cerebrospinal fluid of patients with PD. However, whether 27-OHC plays a role in α-Syn aggregation and propagation remains elusive.

OBJECTIVE

The aim of this study was to determine whether 27-OHC regulates α-Syn aggregation and propagation.

METHODS

Purified recombinant α-Syn, neuronal cultures, and α-Syn fibril-injected mouse model of PD were treated with 27-OHC. In addition, CYP27A1 knockout mice were used to investigate the effect of lowering 27-OHC on α-Syn pathology in vivo.

RESULTS

27-OHC accelerates the aggregation of α-Syn and enhances the seeding activity of α-Syn fibrils. Furthermore, the 27-OHC-modified α-Syn fibrils localize to the mitochondria and induce mitochondrial dysfunction and neurotoxicity. Injection of 27-OHC-modified α-Syn fibrils induces enhanced spread of α-Syn pathology and dopaminergic neurodegeneration compared with pure α-Syn fibrils. Similarly, subcutaneous administration of 27-OHC facilitates the seeding of α-Syn pathology. Genetic deletion of cytochrome P450 27A1 (CYP27A1), the enzyme that converts cholesterol to 27-OHC, ameliorates the spread of pathologic α-Syn, degeneration of the nigrostriatal dopaminergic pathway, and motor impairments. These results indicate that the cholesterol metabolite 27-OHC plays an important role in the pathogenesis of PD.

CONCLUSIONS

27-OHC promotes the aggregation and spread of α-Syn. Strategies aimed at inhibiting the CYP27A1-27-OHC axis may hold promise as a disease-modifying therapy to halt the progression of α-Syn pathology in PD. © 2023 International Parkinson and Movement Disorder Society.

Viral-like TLR3 induction of cytokine networks and α-synuclein are reduced by complement C3 blockade in mouse brain

Inflammatory processes and mechanisms are of central importance in neurodegenerative diseases. In the brain, α-synucleinopathies such as Parkinson's disease (PD) and Lewy body dementia (LBD) show immune cytokine network activation and increased toll like receptor 3 (TLR3) levels for viral double-stranded RNA (dsRNA). Brain inflammatory reactions caused by TLR3 activation are also relevant to understand pathogenic cascades by viral SARS-CoV-2 infection causing post- COVID-19 brain-related syndromes. In the current study, following regional brain TLR3 activation induced by dsRNA in mice, an acute complement C3 response was seen at 2 days. A C3 splice-switching antisense oligonucleotide (ASO) that promotes the splicing of a non-productive C3 mRNA, prevented downstream cytokines, such as IL-6, and α-synuclein changes. This report is the first demonstration that α-synuclein increases occur downstream of complement C3 activation. Relevant to brain dysfunction, post-COVID-19 syndromes and pathological changes leading to PD and LBD, viral dsRNA TLR3 activation in the presence of C3 complement blockade further revealed significant interactions between complement systems, inflammatory cytokine networks and α-synuclein changes.

Metabolomic profiling of a neurodegenerative retina following optic nerve transection

The degeneration of retinal ganglion cells (RGCs) often causes irreversible vision impairment. Prevention of RGC degeneration can prevent or delay the deterioration of visual function. The present study aimed to investigate retinal metabolic profiles following optic nerve transection (ONT) injury and identify the potential metabolic targets for the prevention of RGC degeneration. Retinal samples were dissected from ONT group and non‑ONT group. The untargeted metabolomics were carried out using liquid chromatography‑tandem mass spectrometry. The involved pathways and biomarkers were analyzed using Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis and MetaboAnalyst 5.0. In the ONT group, 689 disparate metabolites were detected, including lipids and lipid‑like molecules. A total of 122 metabolites were successfully annotated and enriched in 50 KEGG pathways. Among them, 'sphingolipid metabolism' and 'primary bile acid biosynthesis' were identified involved in RGC degeneration. A total of five metabolites were selected as the candidate biomarkers for detecting RGC degeneration with an AUC value of 1. The present study revealed that lipid‑related metabolism was involved in the pathogenesis of retinal neurodegeneration. Taurine, taurochenodesoxycholic acid, taurocholic acid (TCA), sphingosine, and galabiosylceramide are shown as the promising biomarkers for the diagnosis of RGC degeneration.

Sphingolipid abnormalities in encephalomyeloradiculoneuropathy (EMRN) are associated with an anti-neutral glycolipid antibody

Accumulating evidence suggests that various sphingolipids and glycosphingolipids can act as mediators for inflammation or signaling molecules in the nervous system. In this article, we explore the molecular basis of a new neuroinflammatory disorder called encephalomyeloradiculoneuropathy (EMRN), which affects the brain, spinal cord, and peripheral nerves; in particular, we discuss whether glycolipid and sphingolipid dysmetabolism is present in patients with this disorder. This review will focus on the pathognomonic significance of sphingolipid and glycolipid dysmetabolism for the development of EMRN and the possible involvement of inflammation in the nervous system.

More than meets the eye in Parkinson's disease and other synucleinopathies: from proteinopathy to lipidopathy

The accumulation of proteinaceous inclusions in the brain is a common feature among neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease (PD), and dementia with Lewy bodies (DLB). The main neuropathological hallmark of PD and DLB are inclusions, known as Lewy bodies (LBs), enriched not only in α-synuclein (aSyn), but also in lipid species, organelles, membranes, and even nucleic acids. Furthermore, several genetic risk factors for PD are mutations in genes involved in lipid metabolism, such as GBA1, VSP35, or PINK1. Thus, it is not surprising that mechanisms that have been implicated in PD, such as inflammation, altered intracellular and vesicular trafficking, mitochondrial dysfunction, and alterations in the protein degradation systems, may be also directly or indirectly connected through lipid homeostasis. In this review, we highlight and discuss the recent evidence that suggests lipid biology as important drivers of PD, and which require renovated attention by neuropathologists. Particularly, we address the implication of lipids in aSyn accumulation and in the spreading of aSyn pathology, in mitochondrial dysfunction, and in ER stress. Together, this suggests we should broaden the view of PD not only as a proteinopathy but also as a lipidopathy.

Neuroinflammation in Parkinson's Disease: From Gene to Clinic: A Systematic Review

Parkinson's disease is a neurodegenerative disease whose progression and clinical characteristics have a close bidirectional and multilevel relationship with the process of neuroinflammation. In this context, it is necessary to understand the mechanisms involved in this neuroinflammation-PD link. This systematic search was, hereby, conducted with a focus on the four levels where alterations associated with neuroinflammation in PD have been described (genetic, cellular, histopathological and clinical-behavioral) by consulting the PubMed, Google Scholar, Scielo and Redalyc search engines, including clinical studies, review articles, book chapters and case studies. Initially, 585,772 articles were included, and, after applying the inclusion and exclusion criteria, 84 articles were obtained that contained information about the multilevel association of neuroinflammation with alterations in gene, molecular, cellular, tissue and neuroanatomical expression as well as clinical-behavioral manifestations in PD.

Relationship of Apolipoprotein E with Alzheimer's Disease and Other Neurological Disorders: An Updated Review

Alzheimer's disease (AD) and other neurodegenerative diseases, for which there is no effective cure, cause great social burden. Apolipoprotein E (APOE) is an important lipid transporter, which has been shown to have a close relationship with AD and other neurological disorders in an increasing number of studies, suggesting its potential as a therapeutic target. In this review, we summarize the recent advances in clinical and basic research on the role of APOE in the pathogenesis of multiple neurological diseases, with an emphasis on the new associations between APOE and AD, and between APOE and depression. The progress of APOE research in Parkinson's disease (PD) and some other neurological diseases is briefly discussed.

The role of microRNA-485 in neurodegenerative diseases

Neurodegenerative diseases (NDDs) are age-related disorders characterized by progressive neurodegeneration and neuronal cell loss in the central nervous system. Neuropathological conditions such as the accumulation of misfolded proteins can cause neuroinflammation, apoptosis, and synaptic dysfunction in the brain, leading to the development of NDDs including Alzheimer's disease (AD) and Parkinson's disease (PD). MicroRNAs (miRNAs) are small noncoding RNA molecules that regulate gene expression post-transcriptionally via RNA interference. Recently, some studies have reported that some miRNAs play an important role in the development of NDDs by regulating target gene expression. MiRNA-485 (miR-485) is a highly conserved brain-enriched miRNA. Accumulating clinical reports suggest that dysregulated miR-485 may be involved in the pathogenesis of AD and PD. Emerging studies have also shown that miR-485 plays a novel role in the regulation of neuroinflammation, apoptosis, and synaptic function in the pathogenesis of NDDs. In this review, we introduce the biological characteristics of miR-485, provide clinical evidence of the dysregulated miR-485 in NDDs, novel roles of miR-485 in neuropathological events, and discuss the potential of targeting miR-485 as a diagnostic and therapeutic marker for NDDs.

A pilot study assessing sphingolipids and glycolipids dysmetabolism in idiopathic normal pressure hydrocephalus

Idiopathic normal pressure hydrocephalus usually exhibits triad of symptoms including gait disturbance, urinary incontinence, and dementia with ventriculomegaly. Currently, its pathogenesis remains to be fully elucidated. To provide a better understanding of this order, we examined whether dysmetabolism of sphingolipids as major lipid components in the brain present in cerebrospinal fluid (CSF) of the patients. Here, we measured various sphingolipidsincluding ceramide and sphingomyelin and glycolipids by electrospray ionization-tandem mass spectrometry in the cerebrospinal fluid of 19 consecutive idiopathic normal pressure hydrocephalus patients, 49 Parkinson's disease patients, and 17 neurologically normal controls. The data showed that there was a significant and specific reduction of all galactosylceramide subspecies levels in idiopathic normal pressure hydrocephalus patients compared with other groups, whereas ceramide and sphingomyelin levels as well as other neutral glycolipids such as glucosylceramide and lactosylceramide were similar in both disease states. Multiple regression analysis of sex and age did not show any correlation with galactosylceramide levels. We also examined whether MMSE scores are correlated with sphingolipid levels in iNPH patients. A specific subspecies of sphingomyelin (d18:1/18:0) only exhibited a statistically significant negative correlation (p = 0.0473, R = -0.4604) with MMSE scores but no other sphingolipids in iNPH patients. These data strongly suggest that myelin-rich galactosylceramide metabolism is severely impaired in idiopathic normal pressure hydrocephalus patients and might serve as the basis of biomarker for this disorder.

Differentiated Embryo-Chondrocyte Expressed Gene1 and Parkinson's Disease: New Insights and Therapeutic Perspectives

Differentiated embryo-chondrocyte expressed gene1 (DEC1), an important transcription factor with a basic helix-loop-helix domain, is ubiquitously expressed in both human embryonic and adult tissues. DEC1 is involved in neural differentiation and neural maturation in the central nervous system (CNS). Recent studies suggest that DEC1 protects against Parkinson's disease (PD) by regulating apoptosis, oxidative stress, lipid metabolism, immune system, and glucose metabolism disorders. In this review, we summarize the recent progress on the role of DEC1 in the pathogenesis of PD and provide new insights into the prevention and treatment of PD and neurodegenerative diseases.

Metabolomics of blood reveals age-dependent pathways in Parkinson’s Disease

Background

Parkinson’s Disease (PD) is the second most frequent degenerative disorder, the risk of which increases with age. A preclinical PD diagnostic test does not exist. We identify PD blood metabolites and metabolic pathways significantly correlated with age to develop personalized age-dependent PD blood biomarkers.

Results

We found 33 metabolites producing a receiver operating characteristic (ROC) area under the curve (AUC) value of 97%. PCA revealed that they belong to three pathways with distinct age-dependent behavior: glycine, threonine and serine metabolism correlates with age only in PD patients; unsaturated fatty acids biosynthesis correlates with age only in a healthy control group; and, finally, tryptophan metabolism characterizes PD but does not correlate with age.

Conclusions

The targeted analysis of the blood metabolome proposed in this paper allowed to find specific age-related metabolites and metabolic pathways. The model offers a promising set of blood biomarkers for a personalized age-dependent approach to the early PD diagnosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13578-022-00831-5.

QEEG indices are associated with inflammatory and metabolic risk factors in Parkinson's disease dementia: An observational study

BACKGROUND

Quantitative electroencephalography (QEEG) is a reliable and non-invasive diagnostic tool to quantify cortical synaptic injury or loss in the clinical assessment of neurodegenerative diseases, and may be able to differentiate various types of dementia. We investigated if QEEG indices can differentiate Parkinson's Disease (PD) with nondementia (PD-ND) from PD with dementia (PDD), and to determine if QEEG indices correlate with inflammation and lipid metabolism markers in PD.

METHODS

This clinical study collected data between July 1, 2018 and July 1, 2021 in Zhujiang Hospital of Southern Medical University in China and data was analysed. A total of 125 individuals comprising of 31 PDD, 47 patients with PD-ND and 47 healthy controls were included. We calculated the absolute spectral power (ASP) of frequency bands and the slow-to-fast frequency ratios of specific brain regions. Plasma levels of hypersensitive C-reactive protein (Hs-CRP), superoxide dismutase (SOD), and high-density lipoprotein cholesterol (HDL-C) were measured and correlations with QEEG indices were examined.

FINDINGS

A significantly higher ASP of delta frequency especially in the frontal region was observed in patients with PDD compared to PD-ND (P=0.004) and controls (P=0.000). Decreased HDL-C (OR=0.186, P=0.030), and increased Hs-CRP (OR =2.856, P=0.015) were associated with PDD. Frontal-delta ASP was negatively correlated with plasma HDL-C (r=-0.353, P=0.000) and SOD (r=-0.322, P=0.001), and positively correlated with Hs-CRP (r=0.342, P=0.000).

INTERPRETATION

We highlight novel correlations between QEEG indices and inflammation and lipid metabolism markers in PD-ND and PDD. QEEG indices, HDL-C and Hs-CRP are potentially useful for the evaluation of PDD. Our current findings suggest that peripheral inflammation might contribute to the pathogenesis of cognitive impairment and EEG slowing in PDD. The mechanism underlying frontal-delta ASP and its correlation with neuro-inflammatory and metabolic markers in PDD should be further investigated.

FUNDING

The National Natural Science Foundation of China (NO: 81873777, 82071414); the Scientific Research Foundation of Guangzhou (NO: 202206010005); the Science and Technology Program of Guangdong of China (NO: 2020A0505100037); the High-level Hospital Construction Research Project of Maoming People's Hospital (NO: xz2020009); the Science and Technology Program of Maoming City (NO: 2021S0026). Dr EK Tan is supported by the National Medical Research Council, Singapore.

APOE in the bullseye of neurodegenerative diseases: impact of the APOE genotype in Alzheimer's disease pathology and brain diseases

ApoE is the major lipid and cholesterol carrier in the CNS. There are three major human polymorphisms, apoE2, apoE3, and apoE4, and the genetic expression of APOE4 is one of the most influential risk factors for the development of late-onset Alzheimer's disease (AD). Neuroinflammation has become the third hallmark of AD, together with Amyloid-β plaques and neurofibrillary tangles of hyperphosphorylated aggregated tau protein. This review aims to broadly and extensively describe the differential aspects concerning apoE. Starting from the evolution of apoE to how APOE's single-nucleotide polymorphisms affect its structure, function, and involvement during health and disease. This review reflects on how APOE's polymorphisms impact critical aspects of AD pathology, such as the neuroinflammatory response, particularly the effect of APOE on astrocytic and microglial function and microglial dynamics, synaptic function, amyloid-β load, tau pathology, autophagy, and cell-cell communication. We discuss influential factors affecting AD pathology combined with the APOE genotype, such as sex, age, diet, physical exercise, current therapies and clinical trials in the AD field. The impact of the APOE genotype in other neurodegenerative diseases characterized by overt inflammation, e.g., alpha- synucleinopathies and Parkinson's disease, traumatic brain injury, stroke, amyotrophic lateral sclerosis, and multiple sclerosis, is also addressed. Therefore, this review gathers the most relevant findings related to the APOE genotype up to date and its implications on AD and CNS pathologies to provide a deeper understanding of the knowledge in the APOE field.

Neuroinflammation in Dementia—Therapeutic Directions in a COVID-19 Pandemic Setting

Although dementia is a heterogenous group of diseases, inflammation has been shown to play a central role in all of them and provides a common link in their pathology. This review aims to highlight the importance of immune response in the most common types of dementia. We describe molecular aspects of pro-inflammatory signaling and sources of inflammatory activation in the human organism, including a novel infectious agent, SARS-CoV-2. The role of glial cells in neuroinflammation, as well as potential therapeutic approaches, are then discussed. Peripheral immune response and increased cytokine production, including an early surge in TNF and IL-1β concentrations activate glia, leading to aggravation of neuroinflammation and dysfunction of neurons during COVID-19. Lifestyle factors, such as diet, have a large impact on future cognitive outcomes and should be included as a crucial intervention in dementia prevention. While the use of NSAIDs is not recommended due to inconclusive results on their efficacy and risk of side effects, the studies focused on the use of TNF antagonists as the more specific target in neuroinflammation are still very limited. It is still unknown, to what degree neuroinflammation resulting from COVID-19 may affect neurodegenerative process and cognitive functioning in the long term with ongoing reports of chronic post-COVID complications.

Parkinson-causing mutations in LRRK2 impair the physiological tetramerization of endogenous α-synuclein in human neurons

α-Synuclein (αSyn) aggregation in Lewy bodies and neurites defines both familial and 'sporadic' Parkinson's disease. We previously identified α-helically folded αSyn tetramers, in addition to the long-known unfolded monomers, in normal cells. PD-causing αSyn mutations decrease the tetramer:monomer (T:M) ratio, associated with αSyn hyperphosphorylation and cytotoxicity in neurons and a motor syndrome of tremor and gait deficits in transgenic mice that responds in part to L-DOPA. Here, we asked whether LRRK2 mutations, the most common genetic cause of cases previously considered sporadic PD, also alter tetramer homeostasis. Patient neurons carrying G2019S, the most prevalent LRRK2 mutation, or R1441C each had decreased T:M ratios and pSer129 hyperphosphorylation of their endogenous αSyn along with increased phosphorylation of Rab10, a widely reported substrate of LRRK2 kinase activity. Two LRRK2 kinase inhibitors normalized the T:M ratio and the hyperphosphorylation in the G2019S and R1441C patient neurons. An inhibitor of stearoyl-CoA desaturase, the rate-limiting enzyme for monounsaturated fatty acid synthesis, also restored the αSyn T:M ratio and reversed pSer129 hyperphosphorylation in both mutants. Coupled with the recent discovery that PD-causing mutations of glucocerebrosidase in Gaucher's neurons also decrease T:M ratios, our findings indicate that three dominant genetic forms of PD involve life-long destabilization of αSyn physiological tetramers as a common pathogenic mechanism that can occur upstream of progressive neuronal synucleinopathy. Based on αSyn's finely-tuned interaction with certain vesicles, we hypothesize that the fatty acid composition and fluidity of membranes regulate αSyn's correct binding to highly curved membranes and subsequent assembly into metastable tetramers.

The Relationship between Procyanidin Structure and Their Protective Effect in a Parkinson's Disease Model

This study evaluated the effect of grape seed-derived monomer, dimeric, and trimeric procyanidins on rat pheochromocytoma cell line (PC12) cells and in a zebrafish Parkinson’s disease (PD) model. PC12 cells were cultured with grape seed-derived procyanidins or deprenyl for 24 h and then exposed to 1.5 mm 1-methyl-4-phenylpyridinium (MPP⁺) for 24 h. Zebrafish larvae (AB strain) 3 days post-fertilization were incubated with deprenyl or grape seed-derived procyanidins in 400 µM 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) for 4 days. The results showed that the procyanidin dimers procyanidin B1 (B1), procyanidin B2 (B2), procyanidin B3 (B3), procyanidin B4 (B4), procyanidin B1-3-O-gallate (B1-G), procyanidin B2-3-O-gallate (B2-G), and the procyanidin trimer procyanidin C1 (C1) had a protective effect on PC12 cells, decreasing the damaged dopaminergic neurons and motor impairment in zebrafish. In PC12 cells and the zebrafish PD model, procyanidin (B1, B2, B3, B4, B1-G, B2-G, C1) treatment decreased the content of reactive oxygen species (ROS) and malondialdehyde (MDA), increased the activity of antioxidant enzymes glutathione peroxidase (GSH-Px), catalase (CAT), and superoxide dismutase (SOD), and upregulated the expression of nuclear factor-erythroid 2-related factor (Nrf2), NAD(P)H: quinone oxidoreductase 1 (NQO1), and heme oxygenase-1 (HO-1). These results suggest that in PC12 cells and the zebrafish PD model, the neuroprotective effects of the procyanidins were positively correlated with their degree of polymerization.

Loss of Drosophila NUS1 results in cholesterol accumulation and Parkinson's disease-related neurodegeneration

NgBR is the Nogo-B receptor, encoded by NUS1 gene. As NgBR contains a C-terminal domain that is similar to cis-isoprenyltransferase (cis-IPTase), NgBR was speculated to stabilize nascent Niemann-Pick type C 2 (NPC2) to facilitate cholesterol transport out of lysosomes. Mutations in the NUS1 were known as risk factors for Parkinson's disease (PD). In our previous study, it was shown that knockdown of Drosophila NUS1 orthologous gene tango14 causes decreased climbing ability, loss of dopaminergic neurons, and decreased dopamine contents. In this study, tango14 mutant flies were generated with a mutation in the C-terminal enzyme activity region using CRISPR/Cas9. Tango14 mutant showed a reduced lifespan with locomotive defects and cholesterol accumulation in Malpighian tubules and brains, especially in dopaminergic neurons. Multilamellar bodies were found in tango14 mutants using electron microscopy. Neurodegenerative-related brain vacuolization was also detected in tango14 knockdown flies in an age-dependent manner. In addition, tango14 knockdown increased α-synuclein (α-syn) neurotoxicity in α-syn-overexpressing flies, with decreased locomotive activities, dopamine contents, and the numbers of dopaminergic neurons in aging flies. Thus, these observations suggest a role of NUS1, the ortholog of tango14, in PD-related pathogenesis.

Association between ABCA7 gene polymorphisms and Parkinson's disease susceptibility in a northern Chinese Han population

OBJECTIVE

As a typical member of the ABC transporter superfamily, ABCA7 has been shown to play an important role in stalling the pathogenesis of neurodegenerative disorders through maintaining the normal microglial function, regulating cellular responses to inflammation and ER stress, and modulating lipid metabolism. Variants in the ABCA7 locus have been hypothesized to be correlated with the genetic predisposition of several neurodegenerative disorders. The goal of this study was to examine whether there is a link between three specific single nucleotide polymorphisms in the ABCA7 gene, namely, rs3764650, rs4147929, and rs3752246, with the risk of developing Parkinson's disease (PD) in a northern Chinese Han community.

METHODS

In this case-control study, we recruited 821 participants, including 411 patients with sporadic PD and 410 independent, healthy controls. A Polymerase Chain Reaction-Restriction Fragment Length Polymorphism genotyping assay was used to identify polymorphisms of the three selected single nucleotide polymorphisms (rs3764650, rs4147929, and rs3752246) of the ABCA7 gene. Sanger sequencing was further applied to identify the accuracy of the genotyping results. The chi-square test was used to compare the frequencies of alleles and genotypes in patients and controls. Odds ratios and 95% confidence intervals were calculated using logistic regression.

RESULTS

We found significant between-group differences in the alleles (A vs. G, nominal P = 0.014) and dominant models (AA + GA vs. GG, nominal P = 0.015) of rs4147929. Subgroup analysis showed that the frequency of the rs4147929 A allele in male patients with PD was significantly higher than that in male controls (nominal P = 0.036). For the rs3752246 polymorphism, the frequency of the G allele was significantly higher in patients with PD than in controls, and the dominant model fit the data best when considering the nominal P-values (nominal P = 0.019, nominal P = 0.033, respectively). Differences in G allele and genotypes frequencies between patients and controls remained significant in women (nominal P = 0.032 for allele, nominal P = 0.015 for genotype), as well as in individuals aged more than 50 years (nominal P = 0.044, nominal P = 0.020, respectively). No significant differences were observed in allele or genotype frequencies between patients with PD and healthy controls for rs3764650. The frequency of the TCG (rs3764650-rs3752246-rs4147929) haplotype was significantly lower in the PD group than in the healthy control group (odds ratio = 0.772; 95% confidence interval = 0.634-0.940; P = 0.011).

CONCLUSION

The rs4147929 polymorphism was significantly associated with PD susceptibility in the northern Chinese Han population. The A allele of rs4147929 was a risk factor for developing PD. The TCG haplotype presented a protective role in the pathogenesis of PD. Further studies using larger sample sizes, considering different clinical and biochemical parameters such as the cognitive status of subjects at the same time, are warranted to better clarify the effects of these common variants on the pathogenesis and development of PD.

Revisiting the miR-200 Family: A Clan of Five Siblings with Essential Roles in Development and Disease

Over two decades of studies on small noncoding RNA molecules illustrate the significance of microRNAs (miRNAs/miRs) in controlling multiple physiological and pathological functions through post-transcriptional and spatiotemporal gene expression. Among the plethora of miRs that are essential during animal embryonic development, in this review, we elaborate the indispensable role of the miR-200 family (comprising miR-200a, -200b, 200c, -141, and -429) in governing the cellular functions associated with epithelial homeostasis, such as epithelial differentiation and neurogenesis. Additionally, in pathological contexts, miR-200 family members are primarily involved in tumor-suppressive roles, including the reversal of the cancer-associated epithelial–mesenchymal transition dedifferentiation process, and are dysregulated during organ fibrosis. Moreover, recent eminent studies have elucidated the crucial roles of miR-200s in the pathophysiology of multiple neurodegenerative diseases and tissue fibrosis. Lastly, we summarize the key studies that have recognized the potential use of miR-200 members as biomarkers for the diagnosis and prognosis of cancers, elaborating the application of these small biomolecules in aiding early cancer detection and intervention.

The Role of miR-20 in Health and Disease of the Central Nervous System

Current understanding of the mechanisms underlying central nervous system (CNS) injury is limited, and traditional therapeutic methods lack a molecular approach either to prevent acute phase or secondary damage, or to support restorative mechanisms in the nervous tissue. microRNAs (miRNAs) are endogenous, non-coding RNA molecules that have recently been discovered as fundamental and post-transcriptional regulators of gene expression. The capacity of microRNAs to regulate the cell state and function through post-transcriptionally silencing hundreds of genes are being acknowledged as an important factor in the pathophysiology of both acute and chronic CNS injuries. In this study, we have summarized the knowledge concerning the pathophysiology of several neurological disorders, and the role of most canonical miRNAs in their development. We have focused on the miR-20, the miR-17~92 family to which miR-20 belongs, and their function in the normal development and disease of the CNS.

MicroRNA Alteration, Application as Biomarkers, and Therapeutic Approaches in Neurodegenerative Diseases

MicroRNAs (miRNAs) are essential post-transcriptional gene regulators involved in various neuronal and non-neuronal cell functions and play a key role in pathological conditions. Numerous studies have demonstrated that miRNAs are dysregulated in major neurodegenerative diseases, such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, amyotrophic lateral sclerosis, or Huntington’s disease. Hence, in the present work, we constructed a comprehensive overview of individual microRNA alterations in various models of the above neurodegenerative diseases. We also provided evidence of miRNAs as promising biomarkers for prognostic and diagnostic approaches. In addition, we summarized data from the literature about miRNA-based therapeutic applications via inhibiting or promoting miRNA expression. We finally identified the overlapping miRNA signature across the diseases, including miR-128, miR-140-5p, miR-206, miR-326, and miR-155, associated with multiple etiological cellular mechanisms. However, it remains to be established whether and to what extent miRNA-based therapies could be safely exploited in the future as effective symptomatic or disease-modifying approaches in the different human neurodegenerative disorders.

Chloramine-T-Enabled Mass Spectrometric Analysis of C═C Isomers of Unsaturated Fatty Acids and Phosphatidylcholines in Human Thyroids

Specific locations of carbon-carbon double bonds (C═C) in lipids often play an essential role in biological processes, and there has been a booming development in C═C composition analysis by mass spectrometry. However, a universal derivatization and fragmentation pattern for the annotation of C═C positions in lipids is still challenging and attractive. To expand this field in lipidomics, a flexible and convenient N-tosylaziridination method was developed, with high derivatization efficiency, sensitivity, and specificity. The derivatization was very fast (15 s), and C═C numbers as well as locations could be pinpointed specifically in tandem mass spectra. By qualitative and quantitative studies of paratumor and tumor thyroid tissues of human beings, the total content of unsaturated fatty acids was suggested to be increased in tumor tissues, and good correlations in and between lysophosphatidylcholines and phosphatidylcholines were revealed by Spearman analysis. Further studies of C═C isomers showed that n-6/n-3 ratios were closely associated with human thyroid tumorigenesis, and high ratios of n-6/n-3 isomers seemed to suffer a high risk of carcinogenesis. Other isomers were not very representative; however, C═C in n-9/n-7 could also be significant for oncology research. Generally, it is supposed that both total amounts and C═C isomer ratios were related to cancer, and N-tosylaziridine derivatization could provide an alternative strategy for the C═C isomer study of disease models.

Multiomics implicate gut microbiota in altered lipid and energy metabolism in Parkinson's disease

We aimed to investigate the link between serum metabolites, gut bacterial community composition, and clinical variables in Parkinson’s disease (PD) and healthy control subjects (HC). A total of 124 subjects were part of the study (63 PD patients and 61 HC subjects). 139 metabolite features were found to be predictive between the PD and Control groups. No associations were found between metabolite features and within-PD clinical variables. The results suggest alterations in serum metabolite profiles in PD, and the results of correlation analysis between metabolite features and microbiota suggest that several bacterial taxa are associated with altered lipid and energy metabolism in PD.

Relationship between Neuroprotective Effects and Structure of Procyanidins

This study evaluated the relationship between the neuroprotective effects of procyanidins and their structural characteristics. In vitro, a rat pheochromocytoma cell line (PC12) was exposed to the grape seed-derived procyanidin monomers: catechin (C), epicatechin (EC), and epicatechin gallate (ECG); the procyanidin dimers: procyanidin B1 (B1), procyanidin B2 (B2), procyanidin B3 (B3), procyanidin B4 (B4), procyanidin B1-3-O-gallate (B1-G), and procyanidin B2-3-O-gallate (B2-G); and the procyanidin trimers: procyanidin C1 (C1) and N-acetyl-l-cysteine (NAC) for 24 h. Cells were then incubated with 200 μM H₂O₂ for 24 h. In vivo, zebrafish larvae (AB strain) 3 days post-fertilization were incubated with NAC or procyanidins (C, EC, ECG, B1, B2, B3, B4, B1-G, B2-G, C1) in 300 µM H₂O₂ for 4 days. Different grape seed procyanidins increased the survival of PC12 cells challenged with H₂O₂, improved the movement behavior disorder of zebrafish caused by H₂O₂, inhibited the increase of ROS and MDA and the decrease of GSH-Px, CAT, and SOD activities, and up-regulated the Nrf2/ARE pathway. The neuroprotective effects of the procyanidin trimer C1 treatment group were greater than the other treatment groups. These results suggest that the neuroprotective effect of procyanidins is positively correlated with their degree of polymerization.

Direct Current Electric Field Coordinates the Migration of BV2 Microglia via ERK/GSK3β/Cofilin Signaling Pathway

Direct current electric field (DCEF) steers the migration of various neural cells. Microglia, as macrophage of the central nervous system (CNS), however, have not been reported to engage in electrotaxis. Here, we applied electric fields to an in vitro environment and found directional migration of BV2 microglia toward the cathode, in a DCEF strength-dependent manner. Transcriptome analysis then revealed significant changes in the mitogen-activated protein kinase cascades. In terms of mechanism, DCEF coordinated microglia movement by regulating the ERK/GSK3β/cofilin signaling pathway, and PMA (protein kinase C activator) reversed cell migration through intervention of the ERK/GSK3β/cofilin axis. Meanwhile, LiCl (GSK3β inhibitor) showed similar functions to PMA in the electrotaxis of microglia. Furthermore, pharmacological and genetic suppression of GSK3β or cofilin also modulated microglia directional migration under DCEF. Collectively, we discovered the electrotaxis of BV2 microglia and the essential role of the ERK/GSK3β/cofilin axis in regulating cell migration via modulation of F-actin redistribution. This research highlights new insight toward mediating BV2 directional migration and provides potential direction for novel therapeutic strategies of CNS diseases.

Defects of Nutrient Signaling and Autophagy in Neurodegeneration

Neurons are post-mitotic cells that allocate huge amounts of energy to the synthesis of new organelles and molecules, neurotransmission and to the maintenance of redox homeostasis. In neurons, autophagy is not only crucial to ensure organelle renewal but it is also essential to balance nutritional needs through the mobilization of internal energy stores. A delicate crosstalk between the pathways that sense nutritional status of the cell and the autophagic processes to recycle organelles and macronutrients is fundamental to guarantee the proper functioning of the neuron in times of energy scarcity. This review provides a detailed overview of the pathways and processes involved in the balance of cellular energy mediated by autophagy, which when defective, precipitate the neurodegenerative cascade of Parkinson's disease, frontotemporal dementia, amyotrophic lateral sclerosis or Alzheimer's disease.

Effect of LRRK2 protein and activity on stimulated cytokines in human monocytes and macrophages

Leucine-rich-repeat kinase 2 (LRRK2), a potential therapeutic target for the treatment of Parkinson's disease (PD), is highly expressed in monocytes and macrophages and may play a role in the regulation of inflammatory pathways. To determine how LRRK2 protein levels and/or its activity modulate inflammatory cytokine/chemokine levels in human immune cells, isogenic human induced pluripotent stem cells (iPSC) with the LRRK2-activating G2019S mutation, wild-type LRRK2, and iPSC deficient in LRRK2 were differentiated to monocytes and macrophages and stimulated with inflammatory toll-like receptor (TLR) agonists in the presence and absence of LRRK2 kinase inhibitors. The effect of LRRK2 inhibitors and the effect of increasing LRRK2 levels with interferon gamma on TLR-stimulated cytokines were also assessed in primary peripheral blood-derived monocytes. Monocytes and macrophages with the LRRK2 G2019S mutation had significantly higher levels of cytokines and chemokines in tissue culture media following stimulation with TLR agonists compared to isogenic controls. Knockout of LRRK2 impaired phagocytosis but did not significantly affect TLR-mediated cytokine levels. Interferon gamma significantly increased the levels of LRRK2 and phosphorylation of its downstream Rab10 substrate, and potentiated TLR-mediated cytokine levels. LRRK2 kinase inhibitors did not have a major effect on TLR-stimulated cytokine levels. Results suggest that the LRRK2 G2019S mutation may potentiate inflammation following activation of TLRs. However, this was not dependent on LRRK2 kinase activity. Indeed, LRRK2 kinase inhibitors had little effect on TLR-mediated inflammation under the conditions employed in this study.

Species-specific accumulation of ceramides in cerebrospinal fluid from encephalomyeloradiculoneurpathy patients associated with peripheral complement activation: A pilot study

Glycolipids are now known to be rapidly converted to mediators for inflammatory reactions or to signaling molecules that control inflammatory events in the nervous system. The present study aimed to explore whether disturbed glycolipids metabolism in the nervous system is present in patients with a neuroinflammatory disorder, encephalo-myelo-radiculo-neuropathy (EMRN), because most EMRN patients have been reported to exhibit autoantibodies against neutral glycolipids. Although molecular pathogenesis of this disorder remains unknown, we tried to search the immunochemical abnormalities in this disorder. ELISA for activated peripheral C5 complement and mass spectrometry analysis of cerebrospinal fluid clearly disclosed a significant upregulation of active C5 complement, C5a levels in sera as well as a significant accumulation of species-specific ceramides but not sphingomyelin in cerebrospinal fluid from EMRN patients. Furthermore, we confirmed the occurrence of anti-neutral glycolipids antibodies in all EMRN patients. Thus, the present study might indicate the pathophysiology of this disorder is the dysregulation of glycolipids metabolism and abnormal production of autoantibodies against neutral glycolipids resulting in the abnormal complement activation, although molecular basis for these sphingolipids dysregulation and the occurrence of autoantibodies against glycolipids remains to be elucidated at present. The present study implicates a new therapeutic strategy employing anti-ceramide and/or anti-complement therapy for this disorder.

Circular RNA circ_0070441 regulates MPP+-triggered neurotoxic effect in SH-SY5Y cells via miR-626/IRS2 axis

Circular RNAs (circRNAs) was suggested to play crucial regulatory roles in various human diseases, including Parkinson's disease (PD). This research aimed to investigate the function and potential mechanism of circ_0070441 in PD. MPP⁺ (1-methyl-4-phenylpyridinium)-treated SH-SY5Y cells was used as an in vitro cellular PD model. The expressions of circ_0070441, microRNA (miR)-626 and insulin receptor substrate 2 (IRS2) were measured by quantitative real-time polymerase chain reaction (RT-qPCR) or western blot. Cell Counting Kit-8 (CCK-8) assay, Cytotoxicity Detection Kit (Lactate Dehydrogenase), flow cytometry and Caspase-3 Assay Kit were used to detect cell viability, LDH release, cell apoptosis and caspase-3 activity, respectively. The levels of inflammation-related factors were detected by enzyme-linked immunosorbent assay (ELISA). The correlation among circ_0070441, miR-626 and IRS2 were confirmed by dual-luciferase reporter assay, RNA immunoprecipitation (RIP) assay and RNA pull-down assay. The levels of circ_0070441 and IRS2 were increased while miR-626 expression was decreased in MPP⁺-treated SH-SY5Y cells in dose- and time-dependent manners. Depletion of circ_0070441 alleviated MPP⁺-triggered neuronal damage by regulating cell apoptosis and inflammation. Circ_0070441 acted as a sponge for miR-626, and IRS2 was a target of miR-626. Besides, the neuroprotective effects of circ_0070441 knockdown or miR-626 overexpression were partly overturned by the suppression of miR-626 or IRS2 overexpression. Moreover, circ_0070441 upregulated IRS2 expression by interacting with miR-626. In summary, circ_0070441 aggravated MPP⁺-triggered neurotoxic effect in SH-SY5Y cells by regulating miR-626/IRS2 axis.

The neuroinflammatory role of glucocerebrosidase in Parkinson's disease

The lysosomal enzyme glucocerebrosidase (GCase), encoded by the GBA1 gene, is a membrane-associated protein catalyzing the cleavage of glucosylceramide (GlcCer) and glucosylsphingosine (GlcSph). Homologous GBA1 mutations cause Gaucher disease (GD) and heterologous mutations cause Parkinson's disease (PD). Importantly, heterologous GBA1 mutations are recognized as the second risk factor of PD. The pathological features of PD are Lewy neurites (LNs) and Lewy bodies (LBs) composed of pathological α-synuclein. Oxidative stress, inflammatory response, autophagic impairment, and α-synuclein accumulation play critical roles in PD pathogenic cascades, but the pathogenesis of PD has not yet been fully elucidated. What's more, PD treatment drugs can only relieve symptoms to a certain extent, but cannot alleviate neurodegenerative progression. Therefore, it's urgent to explore new targets that can alleviate the neurodegenerative process. Deficient GCase can cause lysosomal dysfunction, obstructing the metabolism of α-synuclein. Meanwhile, GCase dysfunction causes accumulation of its substrates, leading to lipid metabolism disorders. Subsequently, astrocytes and microglia are activated, releasing amounts of pro-inflammatory mediators and causing extensive neuroinflammation. All these cascades can induce neuron damage and death, eventually promoting PD pathology. This review aims to summarize these points and the potential of GCase as an original target to provide some ideas for elucidating the pathogenesis of PD.

Systems Biology to Address Unmet Medical Needs in Neurological Disorders

Neurological diseases are highly prevalent and constitute a significant cause of mortality and disability. Neurological disorders encompass a heterogeneous group of neurodegenerative conditions, broadly characterized by injury to the peripheral and/or central nervous system. Although the etiology of neurological diseases varies greatly, they share several characteristics, such as heterogeneity of clinical presentation, non-cell autonomous nature, and diversity of cellular, subcellular, and molecular pathways. Systems biology has emerged as a valuable platform for addressing the challenges of studying heterogeneous neurological diseases. Systems biology has manifold applications to address unmet medical needs for neurological illness, including integrating and correlating different large datasets covering the transcriptome, epigenome, proteome, and metabolome associated with a specific condition. This is particularly useful for disentangling the heterogeneity and complexity of neurological conditions. Hence, systems biology can help in uncovering pathophysiology to develop novel therapeutic targets and assessing the impact of known treatments on disease progression. Additionally, systems biology can identify early diagnostic biomarkers, to help diagnose neurological disease preceded by a long subclinical phase, as well as define the exposome, the collection of environmental toxicants that increase risk of certain neurological diseases. In addition to these current applications, there are numerous potential emergent uses, such as precision medicine.

Identification of blood-based biomarkers for diagnosis and prognosis of Parkinson's disease: A systematic review of proteomics studies

Parkinson's Disease (PD), a neurodegenerative disorder, is characterised by the loss of motor function and dopamine neurons. Therapeutic avenues remain a challenge due to lack of accuracy in early diagnosis, monitoring of disease progression and limited therapeutic options. Proteomic platforms have been utilised to discover biomarkers for numerous diseases, a tool that may benefit the diagnosis and monitoring of disease progression in PD patients. Therefore, this systematic review focuses on analysing blood-based candidate biomarkers (CB) identified via proteomics platforms for PD. This study systematically reviewed articles across six databases (EMBASE, Cochrane, Ovid Medline, Scopus, Science Direct and PubMed) published between 2010 and 2020. Of the 504 articles identified, 12 controlled-PD studies were selected for further analysis. A total of 115 candidate biomarkers (CB) were identified across selected 12-controlled studies, of which 23 CB were found to be replicable in more than two cohorts. Using the PANTHER Go-Slim classification system and STRING network, the gene function and protein interactions between biomarkers were analysed. Our analysis highlights Apolipoprotein A-I (ApoA-I), which is essential in lipid metabolism, oxidative stress, and neuroprotection demonstrates high replicability across five cohorts with consistent downregulation across four cohorts. Since ApoA-I was highly replicable across blood fractions, proteomic platforms and continents, its relationship with cholesterol, statin and oxidative stress as PD biomarker, its role in the pathogenesis of PD is discussed in this paper. The present study identified ApoA-I as a potential biomarker via proteomics analysis of PD for the early diagnosis and prediction of disease progression.

Prevalence of Parkinson's disease in China: a multicenter population-based survey

OBJECTIVE

Few data are available on the current prevalence of Parkinson's disease in China. The aim of this study was to determine the prevalence of Parkinson's disease in Chinese individuals aged 65 years and older and to analyze associated risk factors.

METHODS

We performed a population-based cross-sectional survey with a multistage cluster sampling design. Residents aged 65 and over were drawn from 11 urban districts and 10 rural counties across China. Data were entered into spreadsheets, and imported and analyzed using Statistical Package SPSS 24.

RESULTS

We identified 151 patients with Parkinson's disease among 8124 residents aged 65 and over, including 75 men (49.67%) and 76 women (50.33%). The overall prevalence of PD in the study population was 1.86% (95% confidence interval [CI]: 1.6%-2.2%), and the standardized prevalence of PD was 1.60%. The crude prevalence in men (2.12%) was higher than in women (1.66%), and standardized prevalence in urban areas (1.98%) was higher than in rural areas (1.48%). Logistic regression analysis showed that independent risk factors for PD were older age, heavy metal or pesticide exposure (odds ratio [OR]=3.83; 95% CI: 2.021-7.256), urban residence (OR=1.307; 95% CI: 1.041-1.642), rapid eye movement sleep behavior disorder (OR=1.450; 95% CI: 1.021-2.059), and heart disease (OR=2.431; 95% CI: 1.481-4.990). Conclusion：The prevalence of Parkinson's disease in individuals aged 65 and older in China has not increased significantly in recent years. The prevalence of Parkinson's disease is higher in men than in women and higher in urban areas than in rural areas.