Identifying the potential role of serum miR-20a as a biomarker for olfactory dysfunction in patients with Parkinson's disease.

INTRODUCTION: Olfactory dysfunction (OD), one of the most common non-motor symptoms in Parkinson's disease (PD), is a cardinal prodromal symptom that can appear years before the onset of motor symptoms. Ongoing studies have demonstrated that microRNAs (miRNAs) are suitable biomarkers for PD, while there is a lack of robust miRNAs that can serve as markers for OD in PD. METHODS: The concordantly differentially expressed miRNAs (DE miRNAs) in the damaged olfactory system were first identified in 2 OD-related Gene Expression Omnibus (GEO) datasets. Then, they were verified in another PD-related GEO dataset and only one miRNA (miR-20a) was found to be significantly altered. Serum levels of miR-20a were further measured by qPCR in 79 PD patients with OD (PD-OD), 52 PD patients without OD (PD-NOD), and 52 healthy controls (HC). Objective measure of OD was defined by 16-item Sniffin' Sticks odor identification test. All the participants underwent a demographic and comprehensive PD-related clinical assessment. RESULTS: Our results proved that miR-20a was significantly downregulated in PD-OD compared with PD-NOD and the area under curve (AUC) for OD detection by miR-20a was 0.803 (95% confidence interval, 0.724-0.883). In addition, PD-OD had higher scores of Movement Disorder Society-Unified Parkinson's Disease Rating Scale (UPDRS) II, Hoehn and Yahr stage (H-Y), Non-Motor Symptoms Scale (NMSS) 3, NMSS 5, NMSS 9, Hamilton Rating Scale for Depression (HAMD), Hamilton Anxiety Scale (HAMA), Activity of Daily Living (ADL), and lower scores of Mini-Mental State Examination (MMSE) and 39-item PD Quality of Life Questionnaire (PDQ-39) than PD-NOD. Binary regression model further presented that lower expressions of miR-20a and poorer cognitive function acted as promoting factors in the development of OD. CONCLUSION: Our results suggest that miR-20a could be a novel biomarker for OD in PD and PD-OD patients tend to have higher disease stage, poorer motor aspects of experiences of daily living, worse cognitive scores, and inferior quality of life, and were more likely to have mental disorders. Cognitive function, in particular, is strongly associated with OD in PD patients.

Protective Effects of Querectin against MPP+-Induced Dopaminergic Neurons Injury via the Nrf2 Signaling Pathway.

BACKGROUND: Parkinson's disease (PD) is a common selective and progressive neurodegenerative disorder of nigrostriatal dopaminergic (DA) neurons. Quercetin is a bioflavonoid with antioxidant, anti-inflammatory, anti-aging and anti-cancer properties. However, the exact mechanism by which quercetin exerts its protective effect on DAergic neurons remains unclear. PURPOSE: To investigate the underlying molecular mechanism of quercetin's protective effect on DA neurons using 1-methyl-4-phenylpyridinium (MPP+)-induced PD ferroptosis model in vitro. METHODS: MPP+ was used to induce cytotoxicity in SH-SY5Y/primary neurons. Cell viability and apoptosis were assessed by CCK-8 assay and flow cytometry. The expression levels of ferroptosis-related proteins (NCOA4, SLC7A11, Nrf2, and GPX4) were determined by Western blotting. Malondialdehyde (MDA), iron, and GPX4 levels were assesed using corresponding assay kits. Lipid peroxidation was assessed by C11-BODIPY staining. RESULTS: In the MPP+-induced ferroptosis model of SH-SY5Y cells, the expressions of SLC7A11 and GPX4 were inhibited, and the expression of NCOA4 protein was increased, causing the overproduction of MDA and lipid peroxidation. Quercetin can reduce the above changes caused by MPP+, that is, reduce the protein expression of NCOA4 in SH-SY5Y cells, increase SLC7A11 and GPX4 partially inhibited by MPP+, and reduce MDA overproduction and lipid peroxidation to protect DA neurons. Nrf2 inhibitor ML385 could inhibit quercetin-induced increase of GPX4 and SLC7A11 protein expression, indicating that the protective effect of quercetin was mediated through Nrf2. CONCLUSIONS: The results of this study suggest that quercetin regulates ferroptosis through Nrf2-dependent signaling pathways, thereby inhibiting MPP+-induced neurotoxicity in SH-SY5Y/primary neurons.

Development of gene model combined with machine learning technology to predict for advanced atherosclerotic plaques.

BACKGROUND: Atherosclerosis, as a major cause of stroke, is responsible for a quarter of deaths worldwide. In particular, rupture of late-stage plaques in large vessels such as the carotid artery can lead to serious cardiovascular disease. The aim of our study was to establish a genetic model combined with machining leaning techniques to screen out gene signatures and predict for advanced atherosclerosis plaques. METHODS: The microarray dataset GSE28829 and GSE43292 which were publicly obtained from the Gene Expression Omnibus database were utilized to screen for potential predictive genes. Differentially expressed genes (DEGs) were identified by using the "limma" R package. Gene Ontology (GO) and Kyoto Encyclopedia of Genes Genomes (KEGG) analyses of these DEGs were performed by Metascape. Later, Random Forest (RF) algorithm was applied to further screen out top-30 genes which contribute the most. The expression data of top 30-DEGs were converted into a "Gene Score". Finally, we developed a model based on artificial neural network (ANN) to predict advanced atherosclerotic plaques. The model later was validated in an independent test dataset GSE104140. RESULTS: A total of 176 DEGs were identified in the training datasets. GO and KEGG enrichment analysis revealed that these genes were enriched in leukocyte-mediated immune response, cytokine- cytokine interactions, and immunoinflammatory signaling. Further, top-30 genes (including 25 upregulated and 5 downregulated DEGs) were screened as predictors by RF algorithm. The predictive model was developed with a significantly predictive value (AUC = 0.913) in the training datasets, and was validated with an independent dataset GSE104140 (AUC = 0.827). CONCLUSION: In present study, our prediction model was established and showed satisfactory predictive power in both training and test datasets. In addition, this is the first study adopted bioinformatics methods combined with machine learning techniques (RF and ANN) to explore and predict for the advanced atherosclerotic plaques. However, further investigations were needed to verify the screened DEGs and predictive effectiveness of this model.

Targeting gut-brain axis through scalp-abdominal electroacupuncture in Parkinson's disease.

BACKGROUND: Evidence suggests that the pathogenesis of Parkinson's disease (PD) is initiated in the gut rather than in the brain. Thus, targeting the gut in early stages may have the potential to halt disease progression and alleviate symptoms. Various acupuncture techniques have been used to treat patients with PD and have shown promising results. However, previous acupuncture techniques focused on the brain and motor symptoms. We aimed to determine if targeting PD patients' gut-brain axis through electroacupuncture could be an effective, safe, and low-cost therapeutic option for management of non-motor and motor symptoms. METHODS: Thirty patients with mild to moderate PD were randomised into an intervention (n = 15) and a control group (n = 15). The intervention group received electroacupuncture twice a week for 30 min based on conventional drug treatment for 8 weeks. Conventional drug treatment was continued in the control group. The primary outcomes were changes in the score of clinical scales including the Non-motor Symptom Rating Scale (NMSS), PD Sleep Scale (PDSS), Bristol Stool Function Scale (BSFS), and Patient Associated Constipation and Quality of Life Scale (PAC-QOL). The secondary outcomes were the Unified PD Rating Scale (UPDRS) and Modified Hoehn-Yahr Staging Scale scores. Stool samples from the intervention group were collected before and after the procedure and were sent for gene sequencing. Adverse effects and personal impressions of the patients were noted during the course of the trial. RESULT: An 8-week course of scalp-abdominal electroacupuncture treatment was effective in improving the NMSS, PDSS, and UPDRS scores in patients with PD. Further, there was statistical significance in the two subdomains of NMSS, namely sleep/fatigue and miscellaneous, further implying the efficacy of acupuncture on sleep disturbance. However, although the current acupuncture treatment was gut targeted, it had no effect on BSFS or PAC-QOL. Apart from improved UPDRS motor scores and activities of daily living scores, acupuncture had no significant impact on scores of mentation, behaviour, mood, and therapy complications. Acupuncture did not alter the Hoehn and Yahr stage. Significant alterations in gut bacterial composition were detected in nine taxa at the genus level. The relative abundances of the genera Bacteroides and Parasutterella were significantly increased after the intervention, whereas the abundances of the genera Dialister, Hungatella, Barnesiella, Megasphaera, Allisonella, Intestinimon, and Moryella were significantly lower. CONCLUSION: An 8-week scalp-abdominal electroacupuncture treatment may be a complementary and alternative vehicle for PD patients. We detected nine taxa at the genus level which were significantly altered after treatment, emphasising the role of the gut-brain axis in the process.

The neuroprotective effects of paeoniflorin against MPP+-induced damage to dopaminergic neurons via the Akt/Nrf2/GPX4 pathway.

Paeoniflorin (PF), a water-soluble monoterpene glycoside extracted from the root of Paeonia lactiflora Pall, has been shown to exert neuroprotective effects against neurodegenerative diseases such as Parkinson's disease (PD). However, its underlying mechanisms remain unknown. Our results showed that at certain concentrations, PF alleviated 1-methyl-4-phenylpyridinium (MPP+)-induced morphological damage and inhibited neuronal ferroptosis. Moreover, our research indicated that the neuroprotective effect of PF could be partially blocked by ML385 (a nuclear factor erythroid-2-related factor 2 (Nrf2) inhibitor) and LY29400 (an Akt inhibitor). These findings suggest that PF protects against MPP+-induced neurotoxicity by preventing ferroptosis via activation of the Akt/Nrf2/Gpx4 pathway in vitro.

Diffusion Tensor Imaging Reveals Deep Brain Structure Changes in Early Parkinson's Disease Patients with Various Sleep Disorders.

Parkinson's disease (PD) is a progressive age-related movement disorder caused by dopaminergic neuron loss in the substantia nigra. Diffusion-based magnetic resonance imaging (MRI) studies­namely, diffusion tensor imaging (DTI)­have been performed in the context of PD, either with or without the involvement of sleep disorders (SDs), to deepen our understanding of cerebral microstructural alterations. Analyzing the clinical characteristics and neuroimaging features of SDs in early PD patients is beneficial for early diagnosis and timely invention. In our present study, we enrolled 36 early PD patients (31 patients with SDs and 5 patients without) and 22 healthy controls. Different types of SDs were assessed using the Rapid Eye Movement Sleep Behavior Disorder Questionnaire­Hong Kong, Epworth Sleepiness Scale, International Restless Legs Scale and PD Sleep Scale-2. Brain MRI examinations were carried out in all the participants, and a region-of-interest (ROI) analysis was used to determine the DTI-based fractional anisotropy (FA) values in the substantia nigra (SN), thalamus (Thal) and hypothalamus (HT). The results illustrate that SDs showed a higher prevalence in the early PD patients than in the healthy controls (86.11% vs. 27.27%). Early PD patients with nighttime problems (NPs) had longer courses of PD than those without (5.097 ± 2.925 vs. 2.200 ± 1.095; p < 0.05), and these patients with excessive daytime sleepiness (EDS) or restless legs syndrome (RLS) had more advanced Hoehn and Yahr stages (HY stage) than those without (1.522 ± 0.511 and 1.526 ± 0.513, respectively; both p < 0.05). Compared with the early PD patients without probable rapid eye movement sleep behavior disorder (pRBD), those with pRBD had longer courses, more advanced HY stages and worse motor and non-motor symptoms of PD (course(years), 3.385 ± 1.895 vs. 5.435 ± 3.160; HY stages, 1.462 ± 0.477 vs. 1.848 ± 0.553; UPDRS, 13.538 ± 7.333 vs. 21.783 ± 10.766; UPDRS, 6.538 ± 1.898 vs. 7.957 ± 2.345; all p < 0.05). In addition, the different number of SD types in early PD patients was significantly inversely associated with the severity of damage in the SN and HT. All of the early PD patients with various SDs had injuries in the SN, in whom the damage was more pronounced in patients with NP than those without. Moreover, early PD patients with NP, RLS or pRBD had worse degrees of HT damage than those without. The current study demonstrated the pathophysiological features and neuroimaging changes in early PD patients with various types of sleep disorders, which will help in early diagnosis and therapy.

Proteomics analysis of methylglyoxal-induced neurotoxic effects in SH-SY5Y cells.

Reactive carbonyl compounds contribute to aging, Alzheimer's disease (AD) and other neurodegenerative diseases. Among these compounds, methylglyoxal (MG) can yield advanced glycation end products (AGEs), which are crucial in AD pathogenesis. However, the molecular and biochemical mechanisms of MG neurotoxicity are not completely understood. In the present study, SH-SY5Y cells were treated with MG to induce cell death. 2-D Fluorescence Difference Gel Electrophoresis and matrix-assisted laser desorption/ionization-time of flight mass spectrometry were employed to determine the changes in protein levels in these cells compared with vehicle-treated cells. Proteomics analysis revealed that 49 proteins were differentially expressed in MG-treated SH-SY5Y cells, of which 16 were upregulated and 33 were downregulated. Among them, eight proteins were identified unambiguously. The significant changes in protein levels of actin, immunoglobulin lambda light chain and protein phosphatase 2 were noteworthy given their functional roles in AD pathogenesis. Taken together, our results suggest that multiple pathways are potentially involved in MG-induced neuron death.

Proteomics analysis of MPP+-induced apoptosis in SH-SY5Y cells.

Accumulating evidence suggests that oxidative stress plays a pivotal role in dopaminergic neurodegeneration. However, the kinds of proteins involved in the response to oxidative stress remain unclear. In the present study, SH-SY5Y cells were treated with neurotoxin 1-methyl-4-phenyl-pyridinium ion (MPP+) to induce apoptotic neuronal injury. 2D-DIGE followed by MALDI-TOF-MS was used to determine the changing protein levels. Proteomics analysis revealed that 22 proteins were differentially altered in MPP(+)-treated SH-SY5Y cells, of which 7 were up-regulated proteins and 15 were down-regulated proteins, respectively. Three protein spots were unambiguously identified as sorcin, annexin V, and ribosomal protein P0. The three proteins showed a significant increase in level, suggesting a role in MPP(+)-induced apoptosis. The functional roles of these three proteins collectively indicate that multiple mechanisms are pertinent in the underlying pathogenesis of Parkinson's disease (PD), such as apoptosis, calcium homeostasis, and DNA insults.

Identification of chaperones in a MPP+-induced and ATRA/TPA-differentiated SH-SY5Y cell PD model.

Parkinson's disease (PD) is characterized by the pathological accumulation of misfolded proteins. Molecular chaperones assist in the proper folding of proteins and removal of irreversibly misfolded proteins. This study aims to identify potential chaperones associated with protein misfolding and accumulation in PD. ATRA/TPA-differentiated SH-SY5Y cells were treated with 1 mM of MPP+ for 48 hours. Proteins were analyzed by 2D-DIGE followed by MALDI-ToF MS. The treatment of differentiated SH-SY5Y cells by MPP+ led to the unambiguous identification of 10 protein spots, which corresponds to six proteins. Among these six proteins, four were chaperone proteins including nucleophosmin (NPM1), chaperonin-containing TCP-1 subunit 2 (CCT2 or CCTß), heat shock 90 kDa protein 1 beta (HSP90AB1 or HSP90-ß), and tyrosin3/tryptopha5-monoxygenase activation protein, zeta polypeptide (14-3-3ζ, gene symbol: Ywhaz). To our knowledge, this is the first report that linked the upregulation of chaperones after MPP+ treatment with SH-SY5Y cells. However, the NPM1 protein was identified for the first time in the PD model. The upregulation of four chaperone proteins provided evidence that these chaperones have a complementary effect on protein misfolding in the pathogenesis of PD, and hold promise as a good therapeutic target for PD treatment.

HDAC6 α-tubulin deacetylase: a potential therapeutic target in neurodegenerative diseases.

Histone deacetylases (HDACs), or lysine deacetylases (KDAC), are epigenetic regulators that catalyze the removal of acetyl moieties from the tails of lysine residues of histones and other proteins. To date, eighteen HDAC family members (HDAC1-11 and SIRT1-7) have been identified and grouped into four classes according to their homology to yeast histone deacetylases. HDACs play an important role in regulating gene transcription as well as a variety of cellular functions. Recent studies have found that HDAC6 (α-tubulin deacetylase) has the novel ability to capture α-tubulin as a substrate and regulate the physiological level of its acetylated form. In addition, a growing body of evidence suggests that α-tubulin deacetylase plays a critical role in the cellular response to the accumulation of misfolded and aggregated proteins, which are a prominent pathological feature common to many age-related neurodegenerative disorders such as Alzheimer's, Parkinson's, and Huntington's diseases. Therefore, the role of α-tubulin deacetylase and its potential as a therapeutic target for neurodegenerative diseases are areas of rapidly expanding investigation. Here we review the research of the role played by HDAC6 in the regulation of tubulin modification and aggresome formation. We also summarize the specific inhibitors of HDAC6 and address reports that implicate HDAC6 in various neurodegenerative disorders.

SH-SY5Y human neuroblastoma cell line: in vitro cell model of dopaminergic neurons in Parkinson's disease.

OBJECTIVE: To evaluate the human neuroblastoma SH-SY5Y cell line as an in vitro model of dopaminergic (DAergic) neurons for Parkinson's disease (PD) research and to determine the effect of differentiation on this cell model. DATA SOURCES: The data of this review were selected from the original reports and reviews related to SH-SY5Y cells published in Chinese and foreign journals (Pubmed 1973 to 2009). STUDY SELECTION: After searching the literature, 60 articles were selected to address this review. RESULTS: The SH-SY5Y cell line has become a popular cell model for PD research because this cell line posses many characteristics of DAergic neurons. For example, these cells express tyrosine hydroxylase and dopamine-beta-hydroxylase, as well as the dopamine transporter. Moreover, this cell line can be differentiated into a functionally mature neuronal phenotype in the presence of various agents. Upon differentiation, SH-SY5Y cells stop proliferating and a constant cell number is subsequently maintained. However, different differentiating agents induce different neuronal phenotypes and biochemical changes. For example, retinoic acid induces differentiation toward a cholinergic neuronal phenotype and increases the susceptibility of SH-SY5Y cells to neurotoxins and neuroprotective agents, whereas treatment with retinoic acid followed by phorbol ester 12-O-tetradecanoylphorbol-13-acetate results in a DAergic neuronal phenotype and decreases the susceptibility of cells to neurotoxins and neuroprotective agents. Some differentiating agents also alter kinetics of 1-methyl-4-phenyl-pyridinium (MPP(+)) uptake, making SH-SY5Y cells more similar to primary mesencephalic neurons. CONCLUSIONS: Differentiated and undifferentiated SH-SY5Y cells have been widely used as a cell model of DAergic neurons for PD research. Some differentiating agents afford SH-SY5Y cells with more potential for studying neurotoxicity and neuroprotection and are thus more relevant to experimental PD research.