A skin-specific α-Synuclein seeding amplification assay for diagnosing Parkinson's disease.

The seeding amplification assay (SAA) has recently emerged as a valuable tool for detecting α-synuclein (αSyn) aggregates in various clinically accessible biospecimens. Despite its efficiency and specificity, optimal tissue-specific conditions for distinguishing Parkinson's disease (PD) from non-PD outside the brain remain underexplored. This study systematically evaluated 150 reaction conditions to identify the one with the highest discriminatory potential between PD and non-synucleinopathy controls using skin samples, resulting in a modified SAA. The streamlined SAA achieved an overall sensitivity of 92.46% and specificity of 93.33% on biopsy skin samples from 332 PD patients and 285 controls within 24 h. Inter-laboratory reproducibility demonstrated a Cohen's kappa value of 0.87 (95% CI 0.69-1.00), indicating nearly perfect agreement. Additionally, αSyn seeds in the skin were stable at -80 °C but were vulnerable to short-term exposure to non-ultra-low temperatures and grinding. This study thoroughly investigated procedures for sample preprocessing, seed amplification, and storage, introducing a well-structured experimental framework for PD diagnosis using skin samples.

Low and high doses of oral maslinic acid protect against Parkinson's disease via distinct gut microbiota-related mechanisms.

The use of oral agents that can modify the gut microbiota (GM) could be a novel preventative or therapeutic option for Parkinson's disease (PD). Maslinic acid (MA), a pentacyclic triterpene acid with GM-dependent biological activities when it is taken orally, has not yet been reported to be effective against PD. The present study found both low and high dose MA treatment significantly prevented dopaminergic neuronal loss in a classical chronic PD mouse model by ameliorating motor functions and improving tyrosine hydroxylase expressions in the substantia nigra pars compacta (SNpc) and increasing dopamine and its metabolite homovanillic acid levels in the striatum. However, the effects of MA in PD mice were not dose-responsive, since similar beneficial effects for low and high doses of MA were observed. Further mechanism studies indicated that low dose MA administration favored probiotic bacterial growth in PD mice, which helped to increase striatal serotonin, 5-hydroxyindole acetic acid, and γ-aminobutyric acid levels. High dose MA treatment did not influence GM composition in PD mice but significantly inhibited neuroinflammation as indicated by reduced levels of tumor necrosis factor alpha and interleukin 1ß in the SNpc; moreover, these effects were mainly mediated by microbially-derived acetic acid in the colon. In conclusion, oral MA at different doses protected against PD via distinct mechanisms related to GM. Nevertheless, our study lacked in-depth investigations of the underlying mechanisms involved; future studies will be designed to further delineate the signaling pathways involved in the interactive actions between different doses of MA and GM.

Synaptic potentiation of anterior cingulate cortex contributes to chronic pain of Parkinson's disease.

Parkinson's disease (PD) is a multi-system neurodegenerative disorder. Patients with PD often suffer chronic pain. In the present study, we investigated motor, sensory and emotional changes in three different PD mice models. We found that 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-treatment caused significant changes in all measurements. Mechanical hypersensitivity of PD model induced by MPTP peaked at 3 days and persisted for at least 14 days. Using Fos transgenic mice, we found that neurons in the anterior cingulate cortex (ACC) were activated after MPTP treatment. Inhibiting ACC by bilateral microinjection of muscimol significantly reduced mechanical hypersensitivity and anxiety-like responses. By contrast, MPTP induced motor deficit was not affected, indicating ACC activity is mostly responsible for sensory and emotional changes. We also investigated excitatory synaptic transmission and plasticity using brain slices of MPTP treated animals. While L-LTP was blocked or significantly reduced. E-LTP was not significantly affected in slices of MPTP treated animals. LTD induced by repetitive stimulation was not affected. Furthermore, we found that paired-pulse facilitation and spontaneous release of glutamate were also altered in MPTP treated animals, suggesting presynaptic enhancement of excitatory transmission in PD. Our results suggest that ACC synaptic transmission is enhanced in the animal model of PD, and cortical excitation may play important roles in PD related pain and anxiety.

Cellular and synaptic mechanisms for Parkinson's disease-related chronic pain.

Parkinson's disease is the second most common neurodegenerative disorder after Alzheimer's disease. Chronic pain is experienced by the vast majority of patients living with Parkinson's disease. The degeneration of dopaminergic neuron acts as the essential mechanism of Parkinson's disease in the midbrain dopaminergic pathway. The impairment of dopaminergic neurons leads to dysfunctions of the nociceptive system. Key cortical areas, such as the anterior cingulate cortex (ACC) and insular cortex (IC) that receive the dopaminergic projections are involved in pain transmission. Dopamine changes synaptic transmission via several pathway, for example the D2-adenly cyclase (AC)-cyclic AMP (cAMP)-protein kinase A (PKA) pathway and D1-G protein-coupled receptor kinase 2 (GRK2)-fragile X mental retardation protein (FMRP) pathway. The management of Parkinson's disease-related pain implicates maintenance of stable level of dopaminergic drugs and analgesics, however a more selective drug targeting at key molecules in Parkinson's disease-related pain remains to be investigated.

The outcome and burden of Chinese patients with neurodegenerative diseases: A 10-year clinical feature study.

BACKGROUND: As the Chinese population continues to age, the incidence of neurodegenerative diseases (NDDs) has increased dramatically, which results in heavy medical and economic burden for families and society. OBJECTIVE: The objective of this study was to evaluate NDDs in a southern Chinese hospital over a 10-year period and examine trends in demographics, outcome, length of stay (LOS) and cost. METHODS: Retrospective medical records of patients from January 2010 to December 2019 were collected, including 7231 patients with NDDs (as case group) and 9663 patients without any NDDs (as control group). The information of social demographic data, admission source, reasons for admission, outcomes, LOS, and cost were extracted and analysed. RESULT: The average hospitalisation age of the patients with NDDs is over 65 years (peak age 70-89 years). Compared with the control group, the case group had a longer LOS and a higher cost and the numbers of patients with NDDs increased yearly from 2010 to 2019. The LOS shortened while the cost increased. Clinical features affected LOS and cost. Patients suffering from infection, abnormal blood pressure and the imbalance of water-electrolyte homoeostasis as main reasons for admission were decreased; however, heart disease, cerebrovascular accident and mental diseases were significantly increased, the overall change trend of fracture/trauma remained stable. The rate of discharge to home care and mortality declined; discharge to other medical or community facilities increased over 10 years. CONCLUSION: The majority of NDDs patients tended to be older. During the last 10 years from 2010 to 2019, the numbers of NDDs patients increased yearly, the trend of LOS became shortening and the cost gradually increasing. The main reasons of admission and outcomes of hospital showed different trends.

Dopaminergic neurons show increased low-molecular-mass protein 7 activity induced by 6-hydroxydopamine in vitro and in vivo.

BACKGROUND: Abnormal expression of major histocompatibility complex class I (MHC-I) is increased in dopaminergic (DA) neurons in the substantia nigra (SN) in Parkinson's disease (PD). Low-molecular-mass protein 7 (ß5i) is a proteolytic subunit of the immunoproteasome that regulates protein degradation and the MHC pathway in immune cells. METHODS: In this study, we investigated the role of ß5i in DA neurons using a 6-hydroxydopamine (6-OHDA) model in vitro and vivo. RESULTS: We showed that 6-OHDA upregulated ß5i expression in DA neurons in a concentration- and time-dependent manner. Inhibition and downregulation of ß5i induced the expression of glucose-regulated protein (Bip) and exacerbated 6-OHDA neurotoxicity in DA neurons. The inhibition of ß5i further promoted the activation of Caspase 3-related pathways induced by 6-OHDA. ß5i also activated transporter associated with antigen processing 1 (TAP1) and promoted MHC-I expression on DA neurons. CONCLUSION: Taken together, our data suggest that ß5i is activated in DA neurons under 6-OHDA treatment and may play a neuroprotective role in PD.

Association Analysis of Proteasome Subunits and Transporter Associated with Antigen Processing on Chinese Patients with Parkinson's Disease.

BACKGROUND: Proteasome subunits (PSMB) and transporter associated with antigen processing (TAP) loci are located in the human leukocyte antigen (HLA) Class II region play important roles in immune response and protein degradation in neurodegenerative diseases. This study aimed to explore the association between single nucleotide polymorphisms (SNPs) of PSMB and TAP and Parkinson's disease (PD). METHODS: A case-control study was conducted by genotyping SNPs in PSMB8, PSMB9, TAP1, and TAP2 genes in the Chinese population. Subjects included 542 sporadic patients with PD and 674 healthy controls. Nine identified SNPs in PSMB8, PSMB9, TAP1, and TAP2 were genotyped through SNaPshot testing. RESULTS: The stratified analysis of rs17587 was specially performed on gender. Data revealed that female patients carry a higher frequency of rs17587-G/G versus (A/A + G/A) compared with controls. But there was no significant difference with respect to the genotypic frequencies of the SNPs in PSMB8, TAP1, and TAP2 loci in PD patients. CONCLUSION: Chinese females carrying the rs17587-G/G genotype in PSMB9 may increase a higher risk for PD, but no linkage was found between other SNPs in HLA Class II region and PD.

Dopamine Agonists Exert Nurr1-inducing Effect in Peripheral Blood Mononuclear Cells of Patients with Parkinson's Disease.

BACKGROUND: Nurr1 plays an essential role in the development, survival, and function maintenance of midbrain dopaminergic (DA) neurons, and it is a potential target for Parkinson's disease (PD). Nurr1 mRNA can be detected in peripheral blood mononuclear cells (PBMCs), but whether there is any association of altered Nurr1 expression in PBMC with the disease and DA drug treatments remains elusive. This study aimed to measure the Nurr1 mRNA level in PBMC and evaluate the effect of Nurr1 expression by DA agents in vivo and in vitro. METHODS: The mRNA levels of Nurr1 in PBMC of four subgroups of 362 PD patients and 193 healthy controls (HCs) using real-time polymerase chain reaction were measured. The nonparametric Mann-Whitney U-test and Kruskal-Wallis test were performed to evaluate the differences between PD and HC, as well as the subgroups of PD. Multivariate linear regression analysis was used to evaluate the independent association of Nurr1 expression with Hoehn and Yahr scale, age, and drug treatments. Besides, the Nurr1 expression in cultured PBMC was measured to determine whether DA agonist pramipexole affects its mRNA level. RESULTS: The relative Nurr1 mRNA levels in DA agonists treated subgroup were significant higher than those in recent-onset cases without any anti-PD treatments (de novo) (P < 0.001) and HC groups (P < 0.010), respectively. Furthermore, the increase in Nurr1 mRNA expression was seen in DA agonist and L-dopa group. Multivariate linear regression showed DA agonists, L-dopa, and DA agonists were independent predictors correlated with Nurr1 mRNA expression level in PBMC. In vitro, in the cultured PBMC treated with 10 µmol/L pramipexole, the Nurr1 mRNA levels were significantly increased by 99.61%, 71.75%, 73.16% in 2, 4, and 8 h, respectively (P < 0.001). CONCLUSIONS: DA agonists can induce Nurr1 expression in PBMC, and such effect may contribute to DA agonists-mediated neuroprotection on DA neurons.

Association analysis of HLA-DRA in Chinese patients with sporadic Parkinson's disease.

Our aim is to explore the linkage between single nucleotide polymorphisms (SNPs) in human leukocyte antigen (HLA)-DRA and Parkinson's disease (PD). 542 sporadic PD patients and 674 healthy controls were recruited to investigate this association in the Chinese population by the screening of 15 SNPs in HLA-DRA, and the association of rs3129882 was further re-evaluated by performing meta-analysis and meta-regression analysis. No SNPs in HLA-DRA were significantly associated with PD in the Chinese patients. Although the rs3129882 allele-G frequency in the Caucasian population was lower than that in Chinese population, meta-analysis showed no association of rs3129882 allele-G with PD in the Chinese or Caucasian population. In consideration of the heterogeneity (I(2)=78.6%, Q=66.33, p<0.000), subgroup analysis was performed, revealing a significant association between rs3129882 and PD in the Caucasian patients from the genome-wide association studies (OR=1.22, 95% CI: 1.16, 1.27); however, this association was not consistently observed in the studies performed using other DNA sequencing techniques. Meta-regression analysis, which accounted for 58.3% of the heterogeneity, revealed that the impact of the sequencing technique used was significant (p=0.027) compared with ethnicity. Regression analysis of the Caucasian population further showed that the sequencing technique used contributed to 71.2% of the heterogeneity (p=0.033). Our data support the absence of a linkage between the risk loci in HLA-DRA and PD in Chinese patients. The different DNA sequencing techniques used in PD studies may largely account for the controversial conclusions concerning rs3129882.

Association of serum uric acid levels with the progression of Parkinson's disease in Chinese patients.

BACKGROUND: Uric acid (UA) is suspected to play a neuro-protective role in Parkinson's disease (PD). This study aimed to evaluate whether the serum UA level was associated with the disease progression of PD in a relatively large population of Chinese patients. METHODS: Serum UA levels were measured from 411 Chinese PD patients and 396 age-matched controls; following the uric acid colorimetric method, the serum creatinine (Scr) levels were also measured to reduce the bias caused by possible differences in renal excretion function. The disease progression was scored by Hoehn and Yahr (H&Y) scales and disease durations; PD group was divided into 3 subgroups according to H&Y scales. Independent-samples t test was performed to analyze the differences between PD group and control group. Multiple analysis of covariance was performed to analyze the differences between PD subgroups. Spearman rank-correlation was performed to evaluate the associations between serum UA or Scr level and disease progression. RESULTS: PD patients were found to have significantly lower levels of serum UA than controls ((243.38 ± 78.91) vs. (282.97 ± 90.80) µmol/L, P < 0.01). As the disease progression, the serum UA levels were gradually reduced. There was a significantly inverse correlation of UA levels with H&Y scales (Rs = -0.429, P < 0.01) and disease duration (Rs = -0.284, P < 0.01) in PD patients of both females and males. No significant difference of the Scr level between PD patients and controls was found ((70.01 ± 14.70) vs. (69.84 ± 16.46) µmol/L), and the Scr level was not involved in disease progression. CONCLUSION: Lower serum UA levels may possess a higher risk of PD, which may be a potential useful biomarker to indicate the progression of PD.

Dual androgen-response elements mediate androgen regulation of MMP-2 expression in prostate cancer cells.

AIM: To characterize the matrix metalloproteinases (MMP)-2 promoter and to identify androgen response elements (AREs) involved in androgen-induced MMP-2 expression. METHODS: MMP-2 mRNA levels was determined by reverse transcription-polymerase chain reaction (RT-PCR). MMP-2 promoter-driven luciferase assays were used to determine the fragments responsible for androgen-induced activity. Chromatin-immunoprecipitation assay and electrophoretic mobility shift assays (EMSA) were used to verify the identified AREs in the MMP-2 promoter. RESULTS: Androgen significantly induced MMP-2 expression at the mRNA level, which was blocked by the androgen antagonist bicalutamide. Deletion of a region encompassing base pairs -1591 to -1259 (relative to the start codon) of the MMP-2 promoter led to a significant loss of androgen-induced reporter activity. Additional deletion of the 5'-region up to -562 bp further reduced the androgen-induced MMP-2 promoter activity. Sequence analysis of these two regions revealed two putative ARE motifs. Introducing mutations in the putative ARE motifs by site-directed mutagenesis approach resulted in a dramatic loss of androgen-induced MMP-2 promoter activity, indicating that the putative ARE motifs are required for androgen-stimulated MMP-2 expression. Most importantly, the androgen receptor (AR) interacted with both motif-containing promoter regions in vivo in a chromatin immunoprecipitation assay after androgen treatment. Furthermore, the AR specifically bound to the wild-type but not mutated ARE motifs-containing probes in an in vitro EMSA assay. CONCLUSION: Two ARE motifs were identified to be responsible for androgen-induced MMP-2 expression in prostate cancer cells.

Novel splicing variant of the human orphan nuclear receptor Nurr1 gene.

BACKGROUND: Nurr1 is a member of the nuclear receptor superfamily of transcription factors. The objective of the present study was to identify novel splicing variants of the gene in neuronal and non-neuronal tissues and determine their functions. METHODS: Reverse transcription-polymerase chain reaction (RT-PCR) analysis was used to screen for Nurr1 splice variants in the adult human central nervous system (CNS) and in other tissues such as lymphocytes, and liver, muscle, and kidney cells. Functional assays of the variants were performed by measuring Nurr1 response element (NuRE) transcriptional activity in vitro. RESULTS: In this study, the authors identified a novel splicing variant of Nurr1 within exon 5, found in multiple adult human tissues, including lymphocytes, and liver, muscle, and kidney cells, but not in the brain or spinal cord. Sequencing analysis showed the variant has a 75 bp deletion between nucleotides 1402 and 1476. A functional assay of the Nurr1-c splicing variant, performed by measuring NuRE transcriptional activity in vitro, detected a 39% lower level of luciferase (LUC) activity (P < 0.05). CONCLUSION: A novel splicing variant of Nurr1 exists in human non-neuronal tissues and functional assays suggest that the variant may act as an alternate transcription regulator.