Α-syn Levels Research Articles

Angiotensin-(1-7) relieves behavioral defects and α-synuclein expression through NEAT1/miR-153-3p axis in Parkinson's disease.

Parkinson's disease (PD) is the second most common neurodegenerative disorder, whose characteristic pathology involves progressive deficiency of dopaminergic neurons and generation of Lewy bodies (LBs). Aggregated and misfolded α-synuclein (α-syn) is the major constituent of LBs. As the newly discovered pathway of renin-angiotensin system (RAS), Angiotensin-(1-7) (Ang-(1-7)) and receptor Mas have attracted increasing attentions for their correlation with PD, but underlying mechanisms remain not fully clear. Based on above, this study established PD models of mice and primary dopaminergic neurons with AAV-hα-syn(A53T), then discussed the effects of Ang-(1-7)/Mas on α-syn level and neuronal apoptosis for these models combined with downstream long non-coding RNA (lncRNA) and microRNA (miRNA). Results showed that Ang-(1-7) alleviated behavioral impairments, rescued dopaminergic neurons loss and lowered α-syn expression in substantia nigra of hα-syn(A53T) overexpressed PD mice. We also discovered that Ang-(1-7) decreased level of α-syn and apoptosis in the hα-syn(A53T) overexpressed dopaminergic neurons through lncRNA NEAT1/miR-153-3p axis. Moreover, miR-153-3p level in peripheral blood is found negatively correlated with that of α-syn. In conclusion, our work not only showed neuroprotective effect and underlying mechanisms for Ang-(1-7) on α-syn in vivo and vitro, but also brought new hope on miR-153-3p and NEAT1 for diagnosis and treatment in PD.

Neuropathology in an α-synuclein preformed fibril mouse model occurs independent of the Parkinson's disease-linked lysosomal ATP13A2 protein

Loss-of-function mutations in the ATP13A2 (PARK9) gene are implicated in early-onset autosomal recessive Parkinson's disease (PD) and other neurodegenerative disorders. ATP13A2 encodes a lysosomal transmembrane P5B-type ATPase that is highly expressed in brain and specifically within the substantia nigra pars compacta (SNc). Recent studies have revealed its normal role as a lysosomal polyamine transporter, although its contribution to PD-related pathology remains unclear. Cellular studies report that ATP13A2 can regulate α-synuclein (α-syn) secretion via exosomes. However, the relationship between ATP13A2 and α-syn in animal models remains inconclusive. ATP13A2 knockout (KO) mice exhibit lysosomal abnormalities and reactive astrogliosis but do not develop PD-related neuropathology. Studies manipulating α-syn levels in mice lacking ATP13A2 indicate minimal effects on pathology. The delivery of α-syn preformed fibrils (PFFs) into the mouse striatum is a well-defined model to study the development and spread of α-syn pathology. In this study we unilaterally injected wild-type (WT) and homozygous ATP13A2 KO mice with mouse α-syn PFFs in the striatum and evaluated mice for neuropathology after 6 months. The distribution, spread and extent of α-syn aggregation in multiple regions of the mouse brain was largely independent of ATP13A2 expression. The loss of nigrostriatal pathway dopaminergic neurons and their nerve terminals induced by PFFs were equivalent in WT and ATP13A2 KO mice. Reactive astrogliosis was induced equivalently by α-syn PFFs in WT and KO mice but was already significantly higher in ATP13A2 KO mice due to pre-existing reactive gliosis. We did not identify asymmetric motor disturbances, microglial activation, or axonal damage induced by α-syn PFFs in WT or KO mice. Although α-syn PFFs induce an increase in lysosomal number in the SNc in general, TH-positive dopaminergic neurons did not exhibit either increased lysosomal area or intensity, regardless of genotype. Our study evaluating the spread of α-syn pathology reveals no exacerbation of α-syn pathology, neuronal loss, astrogliosis or motor deficits in ATP13A2 KO mice, suggesting that selective lysosomal abnormalities resulting from ATP13A2 loss do not play a major role in α-syn clearance or propagation in vivo.

Weak association between total alpha‐synuclein reflex tear levels and non‐motor symptoms burden in Parkinson's disease

AbstractBackgroundAlpha‐synuclein (αSyn) is critical to the pathogenesis of Parkinson's disease (PD). Recognition of non‐motor symptoms as clinical manifestations of PD suggests aggregation of αSyn in extranigral areas.AimThis study aimed to evaluate the association between total αSyn levels in reflex tears with non‐motor symptoms.MethodsThis cross‐sectional study included 25 people living with PD (PwP) and 38 age‐matched healthy controls (HC). Total αSyn reflex tear levels were measured using an enzyme‐linked immunosorbent assay. PwP were evaluated using the Non‐Motor Symptoms Scale (NMSS), the Movement Disorders Society Unified Parkinson's Disease Rating Scale (MDS‐UPDRS), Hoehn and Yahr Stage (HY), and Montreal Cognitive Assessment (MoCA).ResultsTotal αSyn reflex tear levels were significantly higher in PwP when compared with HC (1.77 pg/mL [IQR 1.75–1.79] vs. 1.73 pg/mL [IQR 1.70–1.75], p < 0.001). The urinary domain was negatively correlated with total αSyn levels in tears (r = −0.416, p = 0.048). No correlation was observed between total αSyn levels in reflex tears with MDS‐UPDRS, HY, or MoCA.ConclusionsTotal αSyn levels in reflex tears can differentiate PD from HC. In addition, total αSyn reflex tear levels were associated with the urinary domain of NMSS but are not associated with motor and cognitive symptoms, nor HY. Therefore, our findings suggest that it does not reflect ongoing dopaminergic neurodegeneration.

Effect of Preoperative Glucocorticoid Application on Vitreous Parthanatos-Related Protein Expression in Patients with Rhegmatogenous Retinal Detachment Associated with Choroidal Detachment

Purpose The protein concentrations of apoptosis inducing factor (AIF), macrophage migration inhibitory factor (MIF), interleukin-1β (IL-1β), poly ADP ribose polymerase-1 (PARP-1), poly (ADP-ribose) (PAR), α-synuclein (α-SYN), monocyte chemotactic protein‑1 (MCP-1) and tumor necrosis factor-α (TNF-α) in the vitreous of eyes with rhegmatogenous retinal detachment associated with choroidal detachment (RRDCD) were observed and analyzed. Methods A total of 57 patients’ samples were included. 30 patients with RRD were set as the control group, 27 patients with RRDCD were set as the experimental group (16 patients with preoperative glucocorticosteroid (GC+) and 11 patients without preoperative glucocorticosteroid (GC−)). The levels of AIF, MIF, IL-1β, PARP-1, PAR, α-SYN, MCP-1 and TNF-α in vitreous of patients in the control and experimental groups were detected by enzyme-linked immunosorbent assay (ELISA). Results The concentration of AIF in the vitreous was higher in the RRD group (9.96 ± 2.78 ng/ml) than in the RRDCD (GC+) group (7.65 ± 2.13 ng/ml, p = 0.006),the RRDCD (GC+) group was lower than the RRDCD (GC−) group (10.28 ± 2.81 ng/ml) (p = 0.013). The concentration of MIF in vitreous fluid was lower in the RRDCD (GC+) group (61.21 ± 17.56 ng/ml) than in the RRDCD (GC−) group (74.30 ± 9.66 ng/ml, p = 0.039). In the experimental group, the protein concentration of MCP-1 in the RRDCD (GC+) group was higher in the preoperative PVR grading C (284.93 ± 54.96 ng/ml) grade than in the D grade (225.94 ± 24.05 ng/ml) (p = 0.050); The protein concentration of MIF was lower in the RRDCD (GC+) group of patients with an ocular axis of <26 mm (56.19 ± 6.99 ng/ml) than in those with an ocular axis of ≥26 mm (76.26 ± 26.60 ng/ml, p = 0.043). Conclusion Low expression of Parthanatos-related proteins is present in the vitreous of patients with RRDCD (GC+), and preoperative treatment with glucocorticoids may reduce the expression of Parthanatos-related proteins.

Resveratrol and ceftriaxone encapsulated in hybrid nanoparticles to prevent dopaminergic neurons from degeneration for Parkinson's disease treatment

The purpose of this study is to evaluate the influence of phospholipid-polymer nanoparticles (PNPs) on mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) signaling of dopaminergic neurons in degenerated brain. Resveratrol (RES)- and ceftriaxone (CEF)-entrapped PNPs with surface leptin (Lep) and transferrin (Tf) were fabricated to rescue both 1-methyl-4-phenylpyridinium (MPP+)-insulted SH-SY5Y cells and Wistar rats. Based on PNPs, anti-apoptosis of RES and CEF, and targeting of Lep and Tf were investigated. Experimental results revealed that 20–30 % alginic acid (Alg) yielded the maximal particle size, physical stability and entrapment efficiency of CEF, and the minimal release percentage of CEF. Increasing Alg content in PNPs decreased the entrapment efficiency of RES, and facilitated the release of RES. Optimized PNP composition was about 40 % Alg, 15 % phosphatidylserine and 45 % poly-ε-caprolactone. Lep-Tf-PNPs ameliorated brain permeability of RES and CEF without jeopardizing the blood-brain barrier, and promoted the viability of MPP+-insulted SH-SY5Y cells. Immunofluorescence images and western blots of MPP+-insulted SH-SY5Y cells showed that Lep-Tf-RES-CEF-PNPs upregulated dopamine transporter, tyrosine hydroxylase, B-cell lymphoma 2 (Bcl-2), cyclic AMP response element-binding protein and ERK5 expressions, and downregulated Bcl-2-associated X protein (Bax), α-synuclein (α-syn), phosphorylated tau protein (p-tau), c-Jun N-terminal kinase and ERK1/2 expressions. Lep-Tf-RES-CEF-PNPs unveiled a strong capacity to recover Bcl-2, Bax, α-syn and p-tau levels from MPP+ injury in the substantia nigra of rats. Hence, Lep-Tf-RES-CEF-PNPs can retard α-syn fibril formation, prevent tau protein from phosphorylation, and moderate MAPK/ERK and phosphatidylinositol 3-kinase/protein kinase B, and are promising for brain- and neuron-targeted pharmacotherapy to manage Parkinson's disease.

Bee Venom Reduces Early Inflammation and Oxidative Stress Associated with Lipopolysaccharide-induced Alpha-synuclein in the Substantia Nigra-striatum Axis.

Neuroinflammation and oxidative stress are important features in the pathogenesis and development of synucleinopathies, the glial activation and upregulation of pro-inflammatory and oxidative mediators induce alpha-synuclein (α-syn) accumulation. Recent studies have shown that bee venom (BV) has beneficial effects on symptoms of these neurodegenerative diseases. BV is known to exert anti-inflammatory and anti-oxidative effects. Here, we investigated the effects of BV over the different inflammatory and oxidative markers, and in the expression of α-syn and tyrosine hydroxylase (TH) in a lipopolysaccharide (LPS)-induced rat model of synucleinopathies. We examined whether BV (1.5 mg/kg by acupoint injection ST36 six times every 48 h) could change the α-syn and TH expression measured by western blotting, also, observed the activation of microglia and astrocytes by immunofluorescence, quantified the proinflammatory cytokines levels of tumoral necrosis factor-α (TNF-α) and Interleukin-1β (IL-1β) by enzyme-linked immunosorbent assay (ELISA), and estimated the lipid peroxidation and the activity of superoxide dismutase (SOD) and catalase (CAT) by colorimetric kits in LPS-treated rats (2.5 µg by a single dose intranigral injection) in substantia nigra (SN) and striatum (STR) brain areas. In the LPS-injected rat brain, BV treatment reduced α-syn levels and increased the TH levels. In addition, we observed lower microglia and astrocyte activation in SN and STR. Furthermore, BV decreases IL-1β and lipid peroxidation and increases the CAT activity in the STR. These results indicate that BV can restore the α-syn and TH levels possibly by the inhibition of LPS-induced neuroinflammation and oxidation, also, these results suggest that BV could be a promising treatment option for synucleinopathies.

APOE contributes to longitudinal impulse control disorders progression in Parkinson’s disease

BackgroundImpulse control disorders (ICDs) are an increasingly recognized complication in Parkinson disease (PD). The pathogenesis of ICDs is currently unclear. Few genetic studies have been conducted in this area.ObjectiveWe aimed to ascertain the correlation between APOE and ICDs, and identify clinical predictors of ICDs in PD.MethodsThis study included 287 PD patients from the Parkinson’s Progression Markers Initiative. They were followed up to investigate the progression of ICDs over a period of 5 years. The cumulative incidence of ICDs and potential risk factors were evaluated using Kaplan-Meier and Cox regression analyses.Results44.3% (31/70) patients with APOE ɛ4 and 32.3% (70/217) patients without APOE ɛ4 developed ICDs during the five-year follow up period. There were significant differences between the PD with and without ICDs development group in age, MSEADLG score, ESS score, GDS score, and STAI score at baseline. In multivariable Cox regression analysis, APOE ε4 (HR = 1.450, p = 0.048) and STAI score (HR = 1.017, p = 0.001) were predictors of the development of ICDs. Patients with APOE ɛ4 group showed significantly lower CSF Aβ42 and CSF α-syn level than patients without APOE ɛ4 group at baseline. In patients with APOE ɛ4 group, the “low α-syn level” group and the “low ptau/tau ratio” group had a significantly higher incidence of ICDs, respectively.ConclusionsThis study provides important insights into the potential role of the APOE gene in the development of ICDs in PD. Further studies are needed to confirm our findings and to investigate the underlying mechanisms in more detail.

Motor deficits and brain pathology in the Parkinson's disease mouse model hA53Ttg.

Parkinson's disease (PD) is a debilitating neurodegenerative disorder characterized by the progressive loss of dopaminergic neurons and the accumulation of α-synuclein (α-syn) aggregates. The A53T missense point mutation occurs in autosomal dominant familial PD and has been found to promote the aggregation of α-syn. To investigate the role of the A53T mutation in PD, researchers have developed various mouse models with this mutation. We therefore conducted a comprehensive characterization of the tg(THY1-SNCA*A53T)M53Sud mouse model (hA53Ttg mice) for its motor and pathological features. hA53Ttg mice were tested for motor impairments in a series of motor tests at 2, 4 or 6 months of age. Human α-syn and α-syn pSer129, as well as GFAP and Iba1 signal were labeled and quantified in the cortex, hippocampus, and brainstem. Neurofilament light chain (NF-L) levels were measured in the cerebrospinal fluid (CSF) and plasma. Ex vivo analyses were performed at the age of 2, 4, 6, and 10 months. Behavioral tests revealed early muscle weakness and motor impairments that progressed with age. Immunohistochemical analyses demonstrated elevated levels of human α-syn and α-syn pSer129 in all evaluated brain regions. α-syn pSer129 labeling further revealed fiber-like structures in the cortex of older animals. Neuroinflammation was observed in an age-dependent manner. Biochemical evaluation revealed elevated NF-L levels in the plasma and CSF. Overall, our findings highlight the value of hA53Ttg mice in modeling PD-associated pathologies that closely resemble those observed in PD patients. Our results thus suggest that hA53Ttg mice are a useful tool for studying the underlying mechanisms of PD.

α-Synuclein species in plasma neuron-derived extracellular vesicles as biomarkers for iRBD.

Isolated REM sleep behavior disorder (iRBD) is considered as the strongest predictor of Parkinson's disease (PD). Reliable and accurate biomarkers for iRBD detection and the prediction of phenoconversion are in urgent need. This study aimed to investigate whether α-Synuclein (α-Syn) species in plasma neuron-derived extracellular vesicles (NDEVs) could differentiate between iRBD patients and healthy controls (HCs). Nanoscale flow cytometry was used to detect α-Syn-containing NDEVs in plasma. A total of 54 iRBD patients and 53 HCs were recruited. The concentrations of total α-Syn, α-Syn aggregates, and phosphorylated α-Syn at Ser129 (pS129)-containing NDEVs in plasma of iRBD individuals were significantly higher than those in HCs (p < 0.0001 for all). In distinguishing between iRBD and HCs, the area under the receiver operating characteristic (ROC) curve (AUC) for an integrative model incorporating the levels of α-Syn, pS129, and α-Syn aggregate-containing NDEVs in plasma was 0.965. This model achieved a sensitivity of 94.3% and a specificity of 88.9%. In iRBD group, the concentrations of α-Syn aggregate-containing NDEVs exhibited a negative correlation with Sniffin' Sticks olfactory scores (r = -0.351, p = 0.039). Smokers with iRBD exhibited lower levels of α-Syn aggregates and pS129-containing NDEVs in plasma compared to nonsmokers (pα-Syn aggregates = 0.014; ppS129 = 0.003). The current study demonstrated that the levels of total α-Syn, α-Syn aggregates, and pS129-containing NDEVs in the plasma of individuals with iRBD were significantly higher compared to HCs. The levels of α-Syn species-containing NDEVs in plasma may serve as biomarkers for iRBD.

Serum Alpha-synuclein in Restless Legs Syndrome.

To determine any correlation between serum alpha-synuclein (α-syn) concentrations and restless legs syndrome (RLS), and to explore the impact of intravenous iron supplementation on serum α-syn levels. We collected clinical data on 113 RLS patients in whom serum α-syn levels were quantified using an ELISA kit and compared to a group of 45 age matched controls. A subset of 9 RLS patients who received intravenous (IV) iron underwent pre- and post-treatment blood sampling to assess α-syn and ferritin response. Family history of RLS was reported by 62.8% of patients, and current dopaminergic augmentation was observed in 31.0%. Low serum ferritin levels below 75 μg/L were seen in 39.8%. Serum α-syn levels were found to be significantly decreased in RLS patients (mean: 7.7ng/ml) compared to controls (mean: 10.7ng/ml,), p<0.05. Stratification based on sex, age and age of onset, did not reveal significant differences in α-syn levels. In 9 RLS patients who received IV iron treatment, a linear correlation between fold change in α-syn and ferritin was observed (R: 0.7, p <0.05). The temporal relation between serum α-syn and IV iron treatment showed a gradual decline of α-syn and ferritin by time correlation (p = 0.023, R: -0.739). In our study of 113 RLS subjects, serum α-syn levels were decreased in RLS patients compared to healthy controls and increased in the 9 patients who received IV iron treatment in correlation with ferritin. This correlation could suggest a mechanism for reduced dopamine transmission in RLS.

Microglial and neuronal fates following inhibition of CSF-1R in synucleinopathy mouse model

Synucleinopathies are age-related neurological disorders characterized by the abnormal accumulation of α-synuclein (α-syn) in neuronal and non-neuronal cells. It has been proposed that microglial cells play an important role in synucleinopathy neuroinflammation, as well as homeostatically, such as in the clearance of α-syn aggregates in the brain. Here, we examined the effects of microglia on the pathogenesis of synucleinopathies by cell depletion in a mouse model of synucleinopathies. For this purpose, we treated non-transgenic (Non-tg) and α-synuclein transgenic (α-syn-tg) mice with pexidartinib (PLX3397), a tyrosine kinase inhibitor of colony-stimulating factor 1 receptor (CSF-1R). Neuropathological and immunoblot analysis confirmed that Iba-1 immunoreactive microglial cells were decreased by 95% following PLX3397 treatment in Non-tg and α-syn-tg mice. The level of total α-syn in the Triton X-insoluble fraction of brain homogenate was significantly decreased by microglial depletion in the α-syn-tg mice, while the level of Triton X-soluble human α-syn was not affected. Furthermore, the number of p-α-syn immunoreactive inclusions was reduced in α-syn-tg mice treated with PLX3397. Microglial depletion also ameliorated neuronal and synaptic degeneration in α-syn-tg mice, thereby resulted partially improving the motor behavioral deficit in α-syn-tg mice. Moreover, we demonstrated that microglia that survived post-PLX3397 treatment (PLX-resistant microglia) have lower expressions of CSF-1R, and microglial transcriptome analysis further elucidated that PLX-resistant microglia have unique morphology and transcriptomic signatures relative to vehicle-treated microglia of both genotypes; these include differences in definitive microglial functions such as their immune response, cell mobility, cell–cell communications, and regulation of neural homeostasis. Therefore, we suggest that microglia play a critical role in the pathogenesis of synucleinopathies, and that modulation of microglial status might be an effective therapeutic strategy for synucleinopathies.

Genetic spectrum features and diagnostic accuracy of four plasma biomarkers in 248 Chinese patients with frontotemporal dementia.

Frontotemporal dementia (FTD) is characterized by phenotypic and genetic heterogeneities. However, reports on the large Chinese FTD cohort are lacking. Two hundred forty-eight patients with FTD were enrolled. All patients and 2010 healthy controls underwent next generation sequencing. Plasma samples were analyzed for glial fibrillary acidic protein (GFAP), α-synuclein (α-syn), neurofilament light chain (NfL), and phosphorylated tau protein 181 (p-tau181). Gene sequencing identified 48 pathogenic or likely pathogenic mutations in a total of 19.4% of patients with FTD (48/248). The most common mutation was the C9orf72 dynamic mutation (5.2%, 13/248). Significantly increased levels of GFAP, α-syn, NfL, and p-tau181 were detected in patients compared to controls (all p<0.05). GFAP and α-syn presented better performance for diagnosing FTD. We investigated the characteristics of phenotypic and genetic spectrum in a large Chinese FTD cohort, and highlighted the utility of plasma biomarkers for diagnosing FTD. This study used a frontotemporal dementia (FTD) cohort with a large sample size in Asia to update and reveal the clinical and genetic spectrum, and explore the relationship between multiple plasma biomarkers and FTD phenotypes as well as genotypes. We found for the first time that the C9orf72 dynamic mutation frequency ranks first among all mutations, which broke the previous impression that it was rare in Asian patients. Notably, it was the first time the C9orf72 G4C2 repeat expansion had been identified via whole-genome sequencing data, and this was verified using triplet repeat primed polymerase chain reaction (TP-PCR). We analyzed the diagnostic accuracy of four plasma biomarkers (glial fibrillary acidic protein [GFAP], α-synuclein [α-syn], neurofilament light chain [NfL], and phosphorylated tau protein 181 [p-tau181]) at the same time, especially for α-syn being included in the FTD cohort for the first time, and found GFAP and α-syn had the highest diagnostic accuracy for FTD and its varied subtypes.

Possible regulation of the immune modulator tetraspanin CD81 by alpha-synuclein in melanoma

We probed the mechanism by which the Parkinson's disease-associated protein α-synuclein (α-syn)/SNCA promotes the pathogenesis and progression of melanoma. We found that the human melanoma cell line SK-MEL-28 in which SNCA is knocked out (SNCA-KO) has low levels of tetraspanin CD81, which is a cell-surface protein that promotes invasion, migration, and immune suppression. Analyzing data from the Cancer Genome Atlas, we show that SNCA and CD81 mRNA levels are positively correlated in melanoma; melanoma survival is inversely related to the levels of SNCA and CD81; and SNCA/CD81 are inversely related to the expression of key cytokine genes (IL12A, IL12B, IFN, IFNG, PRF1 and GZMB) for immune activation and immune cell-mediated killing of melanoma cells. We propose that high levels of α-syn and CD81 in melanoma and in immune cells drive invasion and migration and in parallel cause an immunosuppressive microenvironment; these contributing factors lead to aggressive melanomas.

Novel Therapeutic Horizons: SNCA Targeting in Parkinson's Disease.

Alpha-synuclein (αSyn) aggregates are the primary component of Lewy bodies, which are pathological hallmarks of Parkinson's disease (PD). The toxicity of αSyn seems to increase with its elevated expression during injury, suggesting that therapeutic approaches focused on reducing αSyn burden in neurons could be beneficial. Additionally, studies have shown higher levels of SNCA mRNA in the midbrain tissues and substantia nigra dopaminergic neurons of sporadic PD post-mortem brains compared to controls. Therefore, the regulation of SNCA expression and inhibition of αSyn synthesis could play an important role in the pathogenesis of injury, resulting in an effective treatment approach for PD. In this context, we summarized the most recent and innovative strategies proposed that exploit the targeting of SNCA to regulate translation and efficiently knock down cytoplasmatic levels of αSyn. Significant progress has been made in developing antisense technologies for treating PD in recent years, with a focus on antisense oligonucleotides and short-interfering RNAs, which achieve high specificity towards the desired target. To provide a more exhaustive picture of this research field, we also reported less common but highly innovative strategies, including small molecules, designed to specifically bind 5'-untranslated regions and, targeting secondary nucleic acid structures present in the SNCA gene, whose formation can be modulated, acting as a transcription and translation control. To fully describe the efficiency of the reported strategies, the effect of αSyn reduction on cellular viability and dopamine homeostasis was also considered.

Alzheimer's Disease Related Biomarkers Were Associated with Amnestic Cognitive Impairment in Parkinson's Disease: A Cross-Sectional Cohort Study.

Cognitive impairment is common in patients with Parkinson's disease (PD) and occurs through multiple mechanisms, including Alzheimer's disease (AD) pathology and the involvement of α-synucleinopathies. We aimed to investigate the pathological biomarkers of both PD and AD in plasma and neuronal extracellular vesicles (EVs) and their association with different types of cognitive impairment in PD patients. A total of 122 patients with PD and 30 healthy controls were included in this cross-sectional cohort study between March 2021 and July 2023. Non-dementia PD patients were divided into amnestic and non-amnestic groups according to the memory domain of a neuropsychological assessment. Plasma and neuronal EV biomarkers, including α-synuclein (α-syn), beta-amyloid (Aβ), total tau (T-tau), phosphorylated tau181 (p-tau181), and glial fibrillary acidic protein (GFAP), were measured using a single-molecule array and a chemiluminescence immunoassay, respectively. Neuronal EV but not plasma α-syn levels, were significantly increased in PD as compared to healthy controls, and they were positively associated with UPDRS part III scores and the severity of cognitive impairment. A lower plasma Aβ42 level and higher neuronal EV T-tau level were found in the amnestic PD group compared to the non-amnestic PD group. The results of the current study demonstrate that neuronal EV α-syn levels can be a sensitive biomarker for assisting in the diagnosis and disease severity prediction of PD. Both AD and PD pathologies are important factors in cognitive impairment associated with PD, and AD pathologies are more involved in amnestic memory deficit in PD.

Rotenone and Its Derivative, Rotenoisin A, Induce Neurodegeneration Differentially in SH-SY5Y Cells.

Rotenone (ROT), the most significant rotenoid, which has shown anticancer activity, has also been reported to be toxic to normal cells, inducing Parkinson's disease (PD)-like neuronal loss with aggregation of α-synuclein (α-syn). To reduce the adverse effects of ROT, its derivative, rotenoisin A (ROA), is obtained by directly irradiating a ROT solution in methanol using γ-rays, which has been reported for potential anticancer properties. However, its PD-inducing effects have not yet been researched or reported. This study sought to compare the activities of ROA and ROT on the aggregation of α-syn, apoptosis, and autophagy in SH-SY5Y cells. ROA decreased cell survival less when compared with ROT on SH-SY5Y cells at 48 h in a dose-dependent manner. ROT (0.5 and 1 μM) and ROA (4 and 5 μM) decreased the expression of tyrosine hydroxylase. Western blot analysis of the Triton X-100 insoluble fraction revealed that both ROT and ROA significantly increased the levels of oligomeric, dimeric, and monomeric phosphorylated Serine129 α-syn and total monomeric α-syn. Moreover, both compounds decreased the proportion of neuronal nuclei, the neurofilament-heavy chain, and β3-tubulin. The phosphorylation of ERK and SAPK were reduced, whereas ROA did not act on Akt. Additionally, the increased Bax/Bcl-2 ratio further activated the downstream caspases cascade. ROT promoted the LC3BII/I ratio and p62 levels; however, different ROA doses resulted in different effects on autophagy while inducing PD-like impairments in SH-SY5Y cells.

High frequency electrical stimulation reduces α-synuclein levels and α-synuclein-mediated autophagy dysfunction

Accumulation of α-synuclein (α-Syn) has been implicated in proteasome and autophagy dysfunction in Parkinson’s disease (PD). High frequency electrical stimulation (HFS) mimicking clinical parameters used for deep brain stimulation (DBS) in vitro or DBS in vivo in preclinical models of PD have been found to reduce levels of α-Syn and, in certain cases, provide possible neuroprotection. However, the mechanisms by which this reduction in α-Syn improves cellular dysfunction associated with α-Syn accumulation remains elusive. Using HFS parameters that recapitulate DBS in vitro, we found that HFS led to a reduction of mutant α-Syn and thereby limited proteasome and autophagy impairments due to α-Syn. Additionally, we observed that HFS modulates via the ATP6V0C subunit of V-ATPase and mitigates α-Syn mediated autophagic dysfunction. This study highlights a role for autophagy in reduction of α-Syn due to HFS which may prove to be a viable approach to decrease pathological protein accumulation in neurodegeneration.

Gba1 E326K renders motor and non-motor symptoms with pathologic α-syn, tau and glial activation.

Mutations in the GBA1 gene are common genetic risk factors for Parkinson's disease (PD), disrupting enzymatic activity and causing lysosomal dysfunction, leading to elevated α-synuclein (α-syn) levels. While GBA1's role in synucleinopathy is well-established, recent research underscores neuroinflammation as a significant pathogenic mechanism in GBA1 deficiency. This study investigates neuroinflammation in Gba1 E326K knock-in mice, a model associated with increased PD and dementia risk. At 9 and 24 months, we assessed GBA1 protein and activity, α-synuclein pathology, neurodegeneration, motor deficits, and gliosis in the ventral midbrain and hippocampus using immunohistochemistry (IHC), Western blot (WB), and GCase assays. Additionally, primary microglia from WT and GBA1E326K/E326K mice were treated with α-syn preformed fibrils (PFF) to study microglia activation, pro-inflammatory cytokines, reactive astrocyte formation, and neuronal death through qPCR, WB, and immunocytochemistry analyses. We also evaluated the effects of gut inoculation of α-syn PFF in Gba1 E326K mice at 7 months and striatal inoculation at 10 months, assessing motor/non-motor symptoms, α-syn pathology, neuroinflammation, gliosis, and neurodegeneration via behavioural tests, IHC, and WB assays. At 24 months, Gba1 E326K knock-in mice showed reduced GCase enzymatic activity and glucosylceramide build-up in the ventral midbrain and hippocampus. Increased pro-inflammatory cytokines and reactive astrocytes were observed in microglia and astrocytes from Gba1 E326K mice treated with pathologic α-syn PFF. Gut inoculation of α-syn PFF increased Lewy body accumulation in the hippocampal dentate gyrus, with heightened microglia and astrocyte activation and worsened non-motor symptoms. Intrastriatal α-syn preformed fibril injection induced motor deficits, reactive glial protein accumulation, and tauopathy in the prefrontal cortex and hippocampus of Gba1 E326K mice. GBA1 deficiency due to the Gba1 E326K mutation exacerbates neuroinflammation and promotes pathogenic α-synuclein transmission, intensifying disease pathology in PD models. This study enhances our understanding of how the Gba1 E326K mutation contributes to neuroinflammation and the spread of pathogenic α-syn in the brain, suggesting new therapeutic strategies for PD and related synucleinopathies.

Elucidating the molecular mechanisms behind the therapeutic impact of median nerve stimulation on cognitive dysfunction post-traumatic brain injury

ObjectiveFerroptosis represents a form of regulated cellular death dependent upon iron and lipid peroxidation derivatives, holding considerable implications for cerebral and neurologic pathologies. In the present study, we endeavored to elucidate the molecular mechanisms governing ferroptosis and appraise the therapeutic value of electrical stimulation of median nerve in addressing cognitive impairments following traumatic brain injury (TBI), employing a rodent model. MethodsIn this study, we established a rat model to investigate the cognitive impairments resulting from TBI, followed by the application of median nerve stimulation (MNS). Initially, rats received an intraperitoneal injection of Erastin (2 mg/kg) prior to undergoing MNS. After 24 h of MNS treatment, the rats were subjected to an open field test to evaluate their cognitive and motor functions. Subsequently, we conducted biochemical assays to measure the serum levels of GSH, MDA and SOD. The structural integrity and cellular morphology of hippocampal tissue were examined through H&E staining, Nissl staining and transmission electron microscopy. Additionally, we assessed the expression levels of proteins crucial for neuronal health and function in the hippocampus, including VEGF, SLC7A11, GPX4, Nrf2, α-syn, NEUN and PSD95. ResultsCompared to the control group, rats in the stimulation group demonstrated enhanced mobility, reduced levels of tissue damage, a decrease in MDA concentration, and increased levels of GSH and SOD. Additionally, there was a significant upregulation in the expression of proteins critical for cellular defense and neuronal health, including GPX4, SLC7A11, Nrf2, VEGF, α-syn, NEUN, and PSD95 proteins. Conversely, rats in the Erastin group demonstrated decreased mobility, exacerbated pathological tissue damage, elevated MDA concentration, and decreased levels of GSH and SOD. There was also a notable decrease in the expression of GPX4, SLC7CA11, Nrf2, and VEGF proteins. The expression levels of α-syn, NEUN, and PSD95 were similarly diminished in the Erastin group. Each of these findings was statistically significant, indicating that MNS exerts neuroprotective effect in the hippocampal tissue of rats with TBI by inhibiting the ferroptosis pathway. Conclusion(1) MNS may enhance the cognitive and behavioral performance of rats after TBI; (2) MNS can play a neuroprotective role by promoting the expression of nerve injury-related proteins, alleviating oxidative stress and ferroptosis process; (3) MNS may inhibit ferroptosis of neuronal cells by activating Nrf2/ GPX4 signaling pathway, thereby improving cognitive impairment in TBI rats.

Rab27b promotes lysosomal function and alpha-synuclein clearance in neurons.

Alpha-synuclein (αsyn) is the key pathogenic protein implicated in synucleinopathies including Parkinson's Disease (PD) and Dementia with Lewy Bodies (DLB). In these diseases, αsyn is thought to spread between cells where it accumulates and induces pathology; however, mechanisms that drive its propagation or aggregation are poorly understood. We have previously reported that the small GTPase Rab27b is elevated in human PD and DLB and that it can mediate the autophagic clearance and toxicity of αsyn in a paracrine αsyn cell culture neuronal model. Here, we expanded our previous work and further characterized a role for Rab27b in neuronal lysosomal processing and αsyn clearance. We found that Rab27b KD in this αsyn inducible neuronal model resulted in lysosomal dysfunction and increased αsyn levels in lysosomes. Similar lysosomal proteolytic defects and enzymatic dysfunction were observed in both primary neuronal cultures and brain lysates from Rab27b knockout (KO) mice. αSyn aggregation was exacerbated in Rab27b KO neurons upon treatment with αsyn preformed fibrils. We found no changes in lysosomal counts or lysosomal pH in either model, but we did identify defects in acidic vesicle trafficking in Rab27b KO primary neurons which may drive lysosomal dysfunction and promote αsyn aggregation. Rab27b OE enhanced lysosomal activity and reduced insoluble αsyn accumulation. Finally we found elevated Rab27b levels in human postmortem incidental Lewy Body Disease (iLBD) subjects relative to healthy controls. These data suggest a role for Rab27b in neuronal lysosomal activity and identify it as a potential therapeutic target in synucleinopathies.