Role of homocysteine in the development and progression of Parkinson's disease

Parkin characteristics and blood biomarkers of Parkinson's disease in WPBLC study

Background

The exact mechanisms of PD are unclear, but Parkin-mediated mitophagy dysfunction is believed to play a key role. We investigated whether blood levels of Parkin and other biomarkers are linked to the risk of developing PD.

Methods

Baseline blood measures of Parkin and other biomarkers, including Homocysteine, carcinoembryonic antigen, Urea, total proteins, total cholesterol, creatine kinase, and albumin, were collected from 197 clinically diagnosed Parkinson's disease participants and 107 age-matched healthy controls in Wenzhou Parkinson's Biomarkers and Living Characteristics study. We conducted bioinformatics analysis using three datasets from the GEO database: GSE90514 (Cohort 1: PD = 4, HC = 4), GSE7621 (Cohort 2: PD = 16, HC = 9), and GSE205450 (Cohort 3: PD = 69, HC = 81).

Results

Using a bioinformatic approach, we identified dysregulated biological processes in PD patients with PRKN mutations. Compared to controls, significant abnormalities were observed in blood levels of Parkin, Hcy, total proteins, urea, albumin, and CEA in PD patients. A model incorporating Parkin, Hcy, total proteins, and urea effectively distinguished PD from healthy controls, achieving a higher accuracy (AUC 0.841) than other biomarker combinations. Gene set enrichment analysis suggested that pathways such as PINK1-Parkin-mediated mitophagy, urea cycle, cysteine degradation, and riboflavin metabolism may be involved in PRKN mutation. Additionally, the link between Parkin and PD was partially mediated by CEA and albumin, not by Hcy, total proteins, or urea.

Conclusion

Our findings indicate that blood Parkin levels may be a minimally invasive biomarker for PD diagnosis. The model, which included Parkin, Hcy, total proteins, and urea, effectively distinguished PD from HC with greater accuracy.

Association Between Homocysteine and All-Cause Mortality Among Osteoarthritis Patients: A Cohort Study from the NHANES Database

This study explored the association between serum Hcy level and the all-cause mortality among osteoarthritis (OA) patients. This cohort study included patients diagnosed as OA from the National Health and Nutrition Examination Survey (NHANES) 1999-2006. Abbott Homocysteine assay, a fully automated fluorescence polarization immunoassay (FPIA) method, was used to measure the level of serum Hcy. Covariates included sociodemographic information, lifestyles, history of diseases and medications were extracted from the database. The weighted univariate, multivariate Cox proportional hazard models and restricted cubic splines (RCS) were utilized to explore the association between Hcy level and all-cause mortality in OA patients, with hazard ratios (HRs) and 95% confidence intervals (CIs). Subgroup analyses based on different age, gender, duration of OA, complications and C-reactive protein (CRP) were further assessed by this association. Totally 1384 OA patients were included in this study, of which 817 (59.03%) died by 31 December 2019. After adjusting all covariates, high Hcy level was associated with the high all-cause mortality among OA patients (HR=1.31, 95%CI: 1.02-1.67), especially in females (HR=1.43, 95%CI: 1.07-1.91), aged >60 years (HR=1.49, 95%CI: 1.14-1.94), duration of OA >10 years (HR=1.40, 95%CI: 1.01-1.95), with the history of hypertension (HR=1.37, 95%CI: 1.03-1.80), without the history of diabetes (HR=1.36, 95%CI: 1.01-1.82) or CRP >0.29 mg/l (HR=1.51, 95%CI: 1.04-2.19). High serum Hcy level was associated with high risk of all-cause mortality in OA patients. Our results suggest that serum Hcy is a promising biomarker for the prognosis of OA patients.

Safety, Tolerability and Pharmacokinetic-Pharmacodynamic Relationship of NX210c Peptide in Healthy Elderly Volunteers: Randomized, Placebo-Controlled, Double-Blind, Multiple Ascending Dose Study

INTRODUCTION

Blood-brain barrier (BBB) integrity is fundamental to brain homeostasis, enabling control of substance exchange and safeguarding neurons against harmful toxins, pathogens, and immune cells that lead to dysregulation and inflammation involved in ageing and neurodegenerative diseases (NDD). The cyclized peptide NX210c is a thrombospondin type 1 repeat analogue derived from subcommissural organ-spondin. It exerts beneficial effects in animal models of NDD owing to its effects on neurons and endothelial cells. NX210c demonstrated a good safety profile in a single ascending dose phase 1a clinical study. The present multiple ascending dose phase 1b study was performed to evaluate the tolerability and pharmacological effects of repeated doses of NX210c in healthy elderly (age: > 55 years) volunteers.

METHODS

This was a randomized, placebo-controlled, double-blind study (EudraCT No. 2022-002868-76), investigating safety/tolerability, pharmacokinetics, and pharmacodynamics (including blood and cerebrospinal fluid biomarkers). Participants received 5 or 10 mg/kg NX210c or placebo (10-min infusion) thrice weekly for 4 weeks in an ascending dose fashion. Follow-up was conducted 2 weeks after last dosing.

RESULTS

The investigation included 29 participants. No serious adverse events were recorded and all adverse events were mild. Dedicated central nervous system testing did not reveal neurotoxicity. Biomarker evaluation showed a statistically significant reduction in blood claudin-5 and a trend toward reduction of blood homocysteine. In silico data modelling revealed salient pharmacokinetic-pharmacodynamic relationships, including reduction of claudin-5, neurofilament light chain, and SPARC-like protein 1 release, and degradation of homocysteine.

CONCLUSION

Multiple doses of NX210c exhibited a good safety profile, showed non-cumulative pharmacokinetics, and exerted pharmacodynamic effects on biomarkers linked to BBB integrity. The effects of NX210c on claudin-5 and biomarkers influencing BBB integrity-and the overarching brain protection it offers-provide a novel therapeutic strategy targeting an underlying driver of neurodegenerative conditions for which disease-modifying treatments are limited or not available.

Multi-omics characterization of improved cognitive functions in Parkinson's disease patients after the combined metabolic activator treatment: a randomized, double-blinded, placebo-controlled phase II trial

Parkinson's disease is primarily marked by mitochondrial dysfunction and metabolic abnormalities. We recently reported that the combined metabolic activators improved the immunohistochemical parameters and behavioural functions in Parkinson's disease and Alzheimer's disease animal models and the cognitive functions in Alzheimer's disease patients. These metabolic activators serve as the precursors of nicotinamide adenine dinucleotide and glutathione, and they can be used to activate mitochondrial metabolism and eventually treat mitochondrial dysfunction. Here, we designed a randomized, double-blinded, placebo-controlled phase II study in Parkinson's disease patients with 84 days combined metabolic activator administration. A single dose of combined metabolic activator contains L-serine (12.35 g), N-acetyl-L-cysteine (2.55 g), nicotinamide riboside (1 g) and L-carnitine tartrate (3.73 g). Patients were administered either one dose of combined metabolic activator or a placebo daily for the initial 28 days, followed by twice-daily dosing for the next 56 days. The main goal of the study was to evaluate the clinical impact on motor functions using the Unified Parkinson's Disease Rating Scale and to determine the safety and tolerability of combined metabolic activator. A secondary objective was to assess cognitive functions utilizing the Montreal Cognitive Assessment and to analyse brain activity through functional MRI. We also performed comprehensive plasma metabolomics and proteomics analysis for detailed characterization of Parkinson's disease patients who participated in the study. Although no improvement in motor functions was observed, cognitive function was shown to be significantly improved (P < 0.0000) in Parkinson's disease patients treated with the combined metabolic activator group over 84 days, whereas no such improvement was noted in the placebo group (P > 0.05). Moreover, a significant reduction (P = 0.001) in Montreal Cognitive Assessment scores was observed in the combined metabolic activator group, with no decline (P > 0.05) in the placebo group among severe Parkinson's disease patients with lower baseline Montreal Cognitive Assessment scores. We showed that improvement in cognition was associated with critical brain network alterations based on functional MRI analysis, especially relevant to areas with cognitive functions in the brain. Finally, through a comprehensive multi-omics analysis, we elucidated the molecular mechanisms underlying cognitive improvements observed in Parkinson's disease patients. Our results show that combined metabolic activator administration leads to enhanced cognitive function and improved metabolic health in Parkinson's disease patients as recently shown in Alzheimer's disease patients. The trial was registered in ClinicalTrials.gov NCT04044131 (17 July 2019, https://clinicaltrials.gov/ct2/show/NCT04044131).

Space exploration and risk of Parkinson's disease: a perspective review

Systemic mitochondrial dysfunction, dopamine loss, sustained structural changes in the basal ganglia including reduced tyrosine hydroxylase, and altered gait- these effects observed in space-flown animals and astronauts mirrors Parkinson's disease (PD). Evidence of mitochondrial changes in space-flown human cells, examined through the lens of PD, suggests that spaceflight-induced PD-like molecular changes are important to monitor during deep space exploration. These changes, may potentially elevate the risk of PD in astronauts.

Homocysteine, neurodegenerative biomarkers, and APOE ε4 in neurodegenerative diseases

INTRODUCTION

Elevated plasma homocysteine (Hcy) is associated with an increased risk of developing neurodegenerative diseases; however, its relationship with the apolipoprotein E (APOE) ε4 allele has not been well characterized.

METHODS

Participants clinically diagnosed with Alzheimer's disease or mild cognitive impairment (AD/MCI), frontotemporal dementia, Parkinson's disease, or cerebrovascular disease were stratified by the presence of the APOE ε4 allele. Volumetric magnetic resonance imaging, plasma amyloid/tau/neurodegeneration biomarkers, and cognitive performance were quantified.

RESULTS

Across all diagnostic groups, Hcy was associated with lower brain parenchymal fraction and greater neurofilament light chain in APOE ε4 non-carriers only. In AD/MCI, Hcy was associated with phosphorylated tau 217 in APOE ε4 non-carriers, but not in carriers. Exploratory analyses revealed interactions between Hcy and APOE ε4 on memory and visuospatial function.

DISCUSSION

Hcy may contribute to neurodegeneration depending on the presence of the APOE ε4 allele and specific disease processes. Trials on vitamin B12 supplementation may consider stratifying by APOE genotype. Highlights Homocysteine (Hcy) was associated with neurodegenerative biomarkers across disease groups. Relationships with Hcy were predominantly found in apolipoprotein E (APOE) ε4 non-carriers. In Alzheimer's disease, associations between Hcy and phosphorylated tau 217 were found in APOE ε4 non-carriers only. Significant interactions existed between Hcy and APOE ε4 status on cognition.

Assessment of the Relationship Between Amino Acid Status and Parkinson's Disease: A Comprehensive Review and Meta-analysis

BACKGROUND

Parkinson's disease (PD) is characterized by the inability of dopamine production from amino acids. Therefore, changes in amino acid profile in PD patients are very critical for understanding disease development. Determination of amino acid levels in PD patients with a cumulative approach may enlighten the disease pathophysiology.

METHODS

A systematic search was performed until February 2023, resulting in 733 articles in PubMed, Web of Science and Scopus databases to evaluate the serum amino acid profile of PD patients. Relevant articles in English with mean/standard deviation values of serum amino acid levels of patients and their healthy controls were included in the meta-analysis.

RESULTS

Our results suggest that valine, proline, ornithine and homocysteine levels were increased, while aspartate, citrulline, lysine and serine levels were significantly decreased in PD patients compared to healthy controls. Homocysteine showed positive correlations with glutamate and ornithine levels. We also analyzed the disease stage parameters: Unified Parkinson's Disease Rating Scale III (UPDRS III) score, Hoehn-Yahr Stage Score, disease duration and levodopa equivalent daily dose (LEDD) of patients. It was observed that LEDD has a negative correlation with arginine levels in patients. UPDRS III score is negatively correlated with phenylalanine levels, and it also tends to show a negative correlation with tyrosine levels. Disease duration tends to be negatively correlated with citrulline levels in PD patients.

CONCLUSION

This cumulative analysis shows evidence of the relation between the mechanisms underlying amino acid metabolism in PD, which may have a great impact on disease development and new therapeutic strategies.

Neuroprotective Effects of Folic Acid: A Review

Folic acid also known as folate and vitamin B9 is of the class of B complex vitamins. It is crucial for homeostatic function of the biological system and is not endogenously produced. It is medically approved for the treatment of megaloblastic anemia. Neurological conditions describe a class of disease conditions that affect the brain, spinal cord and nerves impacting several important functions such as cognition, movement, emotion and sensation. They can arise from a number of causes which may include one or more of genetic factors, infections, injuries, toxins and degenerative process. Homocysteine, a neurotoxic amino acid converted by folic acid has been identified in the pathology of many neurological conditions while folic acid on the other hand has been investigated multiple times for its neuroprotective function and mechanism. Folic acid is involved in the neutralization of homocysteine to its nontoxic form. This article highlights some of the reports of the neuroprotective effect of folic acid against homocysteine toxicity, neurodegenerative diseases, neuropsychiatric conditions, fetal and neonatal neuronal health.

Exploring the causal link between serum amino acids and Parkinson's disease: a Mendelian randomization approach

This study aimed to explore the causal relationships between multiple blood amino acids (BAAs) and the Parkinson's disease (PD). We downloaded genome-wide association study (GWAS) data for BAAs and PD from the OpenGWAS database, screened single nucleotide polymorphisms (SNPs) from the data, and evaluated the causal relationship between BAA levels and PD using the inverse variance weighted (IVW) method. The sensitivity analysis was also conducted. After SNP screening, three amino acid indicators were identified: met-a-308 (phenylalanine), met-a-584 (X-12100 hydroxytryptophan), and met-a-337 (5-hydroxyproline), which showed significant causal relationship with the occurrence of PD. There was no significant heterogeneity or horizontal pleiotropy, and the results were stable. The multivariate MR analysis showed that the mediating effects generated by the introduction of multiple variables were not significant. In conclusion, phenylalanine, X-12,100 hydroxytryptophan, and 5-hydroxyproline have a causal relationship with the occurrence of PD and may be potential early screening biomarkers and blocking targets.

Linking homocysteine and ferroptosis in cardiovascular disease: insights and implications

Homocysteine (Hcy) is a metabolic intermediate product derived from methionine. Hyperhomocysteinemia is a condition associated with various diseases. Hcy is recognized as a risk factor for cardiovascular disease (CVD). Ferroptosis, a novel form of cell death, is primarily characterized by substantial iron accumulation and lipid peroxidation. Recent research indicates a close association between ferroptosis and the pathophysiological processes of tumors, neurological diseases, CVD, and other ailments. However, limited research has been conducted on the impact of Hcy on ferroptosis. Therefore, this paper aimed to investigate the potential roles and mechanisms of homocysteine and ferroptosis in the context of cardiovascular disease. By conducting comprehensive literature research and analysis, we aimed to summarize recent advancements in understanding the effects of homocysteine on ferroptosis in cardiovascular diseases. This research contributes to a profound understanding of this critical domain.

The Impact of the Blood-Brain Barrier and Its Dysfunction in Parkinson's Disease: Contributions to Pathogenesis and Progression

Parkinson's disease (PD) is a brain disorder in which neuronal cells responsible for the release of dopamine, a neurotransmitter that controls movement, are degenerated or impaired in the substantia nigra and basal ganglia. The disease typically affects people over the age of 5 and presents with a variety of motor and nonmotor dysfunctions, which are unique to each person. The impairment of the blood-brain barrier (BBB) and blood retinal barrier (BRB) due to age-related causes such as weakness of tight junctions or rare genetic factors allows several metabolic intermediates to reach and accumulate inside neurons such as Lewy bodies and α-synuclein, disrupting neuronal homeostasis and leading to genetic and epigenetic changes, e.g., damage to the DNA repair system. This perspective highlights the importance of blood barriers, such as the BBB and BRB, in the progression of PD, as the aggregation of Lewy bodies and α-synuclein disrupts neuronal homeostasis. Genetic and epigenetic factors, neuroinflammation, oxidative stress, and mitochondrial dysfunction play crucial roles in the progression of the disease. The implications of these findings are significant; identifying synaptic dysfunction could lead to earlier diagnosis and treatment, while developing targeted therapies focused on preserving synaptic function may slow or halt disease progression. Understanding the various genetic forms of PD could enable more personalized medicine approaches, and using patient-derived midbrain neurons for research may improve the accuracy of PD models due to the implications of an impaired BBB.

Association analyses of nutritional markers with Parkinson's disease and Alzheimer's disease

Introduction

Parkinson's disease (PD) and Alzheimer's disease (AD) are common neurodegenerative diseases with multifaceted etiology. Nutritional and metabolic abnormalities are frequently implicated in PD and AD. In this observational study, we analyzed a series of nutritional markers, and aimed to understand their association with AD and PD risk.

Methods

A total of 424 PD patients, 314 AD patients, and 388 healthy controls were included. Nutritional markers including Hemoglobin A1c, vitamin B12, folate, apolipoprotein B (ApoB), apolipoprotein A1 (ApoA1), low-density lipoprotein (LDL), high-density lipoprotein, triglyceride, total cholesterol (TC), uric acid and homocysteine (HCY) were measured. Significance for odds ratios examining was P < 0.0045 after bonferroni correction.

Results

Multifactor risk analysis showed that ApoB, LDL, and TC reduce PD risk, while HCY increase PD risk. ApoA1 and HCY are protective and risk factors for AD, respectively.

Conclusion

The cross-sectional study demonstrates that HCY and lipid metabolism markers are associated with PD and AD risks. Our findings support the involvement of one-carbon metabolism and lipid metabolism disturbance in PD and AD.

Association analysis of MTHFR (rs1801133 and rs1801131) gene polymorphism towards the development of type 2 diabetes mellitus in Dali area population from Yunnan Province, China

Background

Type 2 diabetes mellitus (T2DM) is a common complex metabolic disorder that exhibits a strong genetic predisposition. 5,10-methylenetetrahydrofolate reductase (MTHFR) regulates folate metabolism, which has been proposed to be associated with T2DM, although the relationship is inconsistent among different geographical areas. This study aimed to investigate the effects of MTHFR C677T (rs1801133) and A1298C (rs1801131) loci polymorphisms on T2DM susceptibility in the population of the Dali area in Yunnan Province, China.

Methods

This case-control study included 445 patients with T2DM and 272 healthy control individuals from the Dali area of Yunnan Province. Genotyping of the MTHFR gene polymorphisms was performed using the competitive allele-specific PCR (KASP) method. The effects of genetic variations of the MTHFR gene on T2DM risk were evaluated using odds ratios (OR) and 95% confidence intervals.

Results

The results of the present study revealed that the TT genotype (OR = 1.750, P = 0.030) and the T allele (OR = 1.252, P = 0.047) at the MTHFR C677T locus were considerably associated with the increased odds of developing T2DM. In addition, the CC genotype (OR = 3.132, P = 0.032) at the MTHFR A1298C locus also substantially increased the odds of developing T2DM. The T-A haplotype (OR = 1.305, P = 0.030) of MTHFR C677T and A1298C exhibited the increased odds of developing T2DM. Biochemical index analyses showed that patients with T2DM who carried the CT or TT genotype of MTHFR C677T expressed substantially higher levels of fasting blood glucose (FBG), homocysteine (Hcy), and tumor necrosis factor-alpha (TNF-α) than those of the CC genotype. Moreover, the FBG and Hcy levels were considerably higher in patients with T2DM who carried the CC or AC genotype of MTHFR A1298C than those of the AA genotype. No obvious association was observed between these MTHFR polymorphisms and cardiovascular risk in T2DM.

Conclusion

Our study suggests that the genetic variations of MTHFR C677T and A1298C are significantly associated with T2DM susceptibility in the population of the Dali area of Yunnan Province, China.

The Imbalance of Homocysteine, Vitamin B12 and Folic Acid in Parkinson Plus Syndromes: A Review beyond Parkinson Disease

While there is a link between homocysteine (Hcy), B12 and folic acid and neurodegeneration, especially in disorders like Parkinson's and Alzheimer's diseases, its role in Parkinson plus syndromes (PPS) has only been partially investigated. It appears that elevated Hcy, along with an imbalance of its essential vitamin cofactors, are both implicated in the development and progression of parkinsonian syndromes, which represent different disease pathologies, namely alpha-synucleinopathies and tauopathies. Attributing a potential pathogenetic role in hyperhomocysteinemia would be crucial in terms of improving the diagnostic and prognostic accuracy of these syndromes and also for providing a new target for possible therapeutic intervention. The scope of this review is to focus on vitamin imbalance in PPS, with a special emphasis on the role of Hcy, B12 and folic acid in the neurodegenerative process and their implication in the therapeutic approach of these disorders.

Amentoflavone attenuates homocysteine-induced neuronal ferroptosis-mediated inflammatory response: Involvement of the SLC7A11/GPX4 axis activation

Elevated homocysteine (Hcy) levels, referred to hyperhomocysteinemia, are associated with an increased risk of several neurological disorders. Ferroptosis and inflammation play a vital role in Hcy-induced neuronal dysfunction. Amentoflavone (AMF), an active natural biflavone compound, exhibits antioxidative, anti-inflammatory, and neuroprotective activities. This study aimed to explore the potential effects of AMF on Hcy-induced neuronal injury, with a particular focus on the underlying mechanisms involving ferroptosis and inflammation. We assessed neuronal damage in HT22 cells by measuring cell viability, lactate dehydrogenase (LDH) release, and proliferation rates. Additionally, we evaluated oxidative stress markers including the levels of reactive oxygen species (ROS), MitoSOX, mitochondrial membrane potential (MMP), malondialdehyde (MDA), and glutathione (GSH). Iron metabolism and ferroptosis-related gene expressions (Ptgs2, Tfr1, and Fth1) were quantified. TheSLC7A11/GPX4 axis was also detected. Our results showed that AMF treatment dramatically mitigated Hcy-induced neuronal injury by increasing cell viability, decreasing LDH release, and promoting cell proliferation. AMF treatment also reduced Hcy-induced oxidative stress and lipid peroxidation, as evidenced by reduced ROS, MitoSOX, MMP, and MDA levels, along with an increased GSH content in HT22 cells. In addition, AMF treatment reduced iron content and ferroptosis-related gene mRNA levels. However, Erastin, a ferroptosis inducer, blocked these neuroprotective effects of AMF. Ferroptosis inhibitor Ferrostatin-1 also attenuated Hcy-induced ferroptosis. Moreover, both AMF and Ferrostatin-1 effectively mitigated Hcy-induced inflammation, which was again antagonized by Erastin. Mechanistically, AMF treatment enhanced SLC7A11/GPX4 axis in Hcy-treated HT22 cells. In conclusion, these findings suggest that AMF possesses neuroprotection against Hcy-induced injury primarily by inhibiting ferroptosis-mediated inflammation, partly through the activation of SLC7A11/GPX4 axis.

H2S prevents the disruption of the blood-brain barrier in rats with prenatal hyperhomocysteinemia

Elevation of the homocysteine concentration in the plasma called hyperhomocysteinemia (hHCY) during pregnancy causes a number of pre- and postnatal developmental disorders. The aim of our study was to analyze the effects of H2S donors -NaHS and N-acetylcysteine (NAC) on blood-brain barrier (BBB) permeability in rats with prenatal hHCY. In rats with mild hHCY BBB permeability assessed by Evans Blue extravasation in brain increased markedly throughout life. Administration of NaHS or NAC during pregnancy attenuated hHCY-associated damage and increased endogenous concentrations of sulfides in brain tissues. Acute application of dl-homocysteine thiolactone induced BBB leakage, which was prevented by the NMDA receptor antagonist MK-801 or H2S donors. Rats with hHCY demonstrated high levels of NO metabolite - nitrites and proinflammatory cytokines (IL-1β, TNF-α, IL-6) in brain. Lactate dehydrogenase (LDH) activity in the serum was higher in rats with hHCY. Mitochondrial complex-I activity was lower in brain of hHCY rats. NaHS treatment during pregnancy restored levels of proinflammatory cytokines, nitrites and activity of the respiratory chain complex in brain as well as the LDH activity in serum. Our data suggest that H2S has neuroprotective effects against prenatal hHCY-associated BBB disturbance providing a potential strategy for the prevention of developmental impairments in newborns.

Progression of cognitive impairment in Parkinson's disease correlates with uric acid concentration

Introduction

This study assessed the relationship between the progression of Parkinson's disease (PD) with cognitive impairment and changes in serum uric acid (UA) and homocysteine (Hcy) concentrations and explored the factors influencing PD with cognitive impairment.

Methods

The study randomly selected 74 patients with PD and evaluated their cognitive function using the Montreal Cognitive Assessment Scale (MoCA). Patients with PD were divided into two subgroups: those with and without cognitive impairment. PD severity was evaluated and graded using the Hoehn and Yahr (H-Y) scale. Another 60 middle-aged and older individuals without PD during the same period were selected as a control group. Blood UA and Hcy concentrations in each group were measured to assess the relationship between PD, cognitive impairment, and changes in UA and Hcy concentrations.

Results

The PD group with cognitive impairment had a lower UA concentration and higher Hcy concentration. The UA concentration was significantly higher in the early PD stages than in the middle and late stages (P<0.05). A significant negative relationship between MoCA scores and serum UA levels was found in patients with PD, whereas a positive relationship existed between MoCA scores and serum Hcy concentrations. Regression analysis showed that a higher UA concentration was an independent protective factor for PD with cognitive impairment, while a higher Hcy concentration was a risk factor (P<0.05). A serum UA concentration of 212.9 mmol/L and Hcy concentration of 13.35 mmol/L could distinguish between patients with PD with or without cognitive impairment with a sensitivity of 93.2% and specificity of 43.3%.

Conclusion

PD and cognitive impairment were associated with a decrease in UA concentration; the later the H-Y stage was, the lower the UA concentration was. The increase in Hcy concentration was related to PD and its cognitive impairment, whereas it is not significantly correlated with PD progression.

Nonlinear Relationship Between Homocysteine and Mild Cognitive Impairment in Early Parkinson's Disease: A Cross-Sectional Study

Background

Cognitive impairment, a prevalent non-motor symptom in advanced Parkinson's disease (PD), has been associated with hyperhomocysteinemia, an important risk factor for PD progression and cognitive decline in PD. However, evidence regarding the association between homocysteine (Hcy) and cognitive function during early PD remains insufficient. Therefore, this study aims to examine the correlation between Hcy levels and cognitive function in the early stage of PD.

Methods

The study included 218 individuals in the early stages of PD who were consecutively admitted to the Suining Central Hospital Neurology Department. All the individuals completed the Parkinson's Disease Cognitive Rating Scale (PD-CDR). The Unified Parkinson's Disease Rating Scale part III (UPDRS-III) was employed for measuring the severity of motor symptoms, while the Hoehn-Yahr scale was used to measure the clinical symptom stage. Fasting venous blood samples were also drawn to measure the Hcy concentration, red blood cell folate, and vitamin B12.

Results

In this cross-sectional study, 47 (21.5%) patients with PD showed cognitive dysfunction. The serum Hcy levels were significantly higher in the cognitive impairment PD (PDCI) group compared with the cognitive normal PD group (P<0.001). The Generalized Additive Model (GAM) analysis revealed a nonlinear relationship between Hcy and the risk of PDCI. Multiple logistic regression analyses demonstrated a positive relationship between elevated Hcy and the risk of PDCI in the fully adjusted model ([OR]:3.1, 95% CI, 1.1-8.5, P=0.028). Segmented linear regression analysis showed that when Hcy levels were above 17.7 umol/l, the risk of PDCI increased by 1.6 times for every 1 unit elevated in Hcy (95% CI:1.1-2.2, P=0.008).

Conclusion

This study revealed a nonlinear positive correlation between the risk of PDCI and elevated serum Hcy levels in early PD patients, suggesting hyperhomocysteinemia as one of the treatable factors for cognitive impairment in the early stages of PD.

Metformin role in Parkinson's disease: a double-sword effect

Parkinson's disease (PD) is a common neurodegenerative disease developed due to the degeneration of dopaminergic neurons in the substantia nigra. There is no single effective treatment in the management of PD. Therefore, repurposing effective and approved drugs like metformin could be an effective strategy for managing PD. However, the mechanistic role of metformin in PD neuropathology was not fully elucidated. Metformin is an insulin-sensitizing agent used as a first-line therapy in the management of type 2 diabetes mellitus (T2DM) and has the ability to reduce insulin resistance (IR). Metformin may have a beneficial effect on PD neuropathology. The neuroprotective effect of metformin is mainly mediated by activating adenosine monophosphate protein kinase (AMPK), which reduces mitochondrial dysfunction, oxidative stress, and α-synuclein aggregation. As well, metformin mitigates brain IR a hallmark of PD and other neurodegenerative diseases. However, metformin may harm PD neuropathology by inducing hyperhomocysteinemia and deficiency of folate and B12. Therefore, this review aimed to find the potential role of metformin regarding its protective and detrimental effects on the pathogenesis of PD. The mechanistic role of metformin in PD neuropathology was not fully elucidated. Most studies regarding metformin and its effectiveness in PD neuropathology were observed in preclinical studies, which are not fully translated into clinical settings. In addition, metformin effect on PD neuropathology was previously clarified in T2DM, potentially linked to an increasing PD risk. These limitations hinder the conclusion concerning the therapeutic efficacy of metformin and its beneficial and detrimental role in PD. Therefore, as metformin does not cause hypoglycemia and is a safe drug, it should be evaluated in non-diabetic patients concerning PD risk.

Metabolic rescue of α-synuclein-induced neurodegeneration through propionate supplementation and intestine-neuron signaling in C. elegans

Microbial metabolites that can modulate neurodegeneration are promising therapeutic targets. Here, we found that the short-chain fatty acid propionate protects against α-synuclein-induced neuronal death and locomotion defects in a Caenorhabditis elegans model of Parkinson's disease (PD) through bidirectional regulation between the intestine and neurons. Both depletion of dietary vitamin B12, which induces propionate breakdown, and propionate supplementation suppress neurodegeneration and reverse PD-associated transcriptomic aberrations. Neuronal α-synuclein aggregation induces intestinal mitochondrial unfolded protein response (mitoUPR), which leads to reduced propionate levels that trigger transcriptional reprogramming in the intestine and cause defects in energy production. Weakened intestinal metabolism exacerbates neurodegeneration through interorgan signaling. Genetically enhancing propionate production or overexpressing metabolic regulators downstream of propionate in the intestine rescues neurodegeneration, which then relieves mitoUPR. Importantly, propionate supplementation suppresses neurodegeneration without reducing α-synuclein aggregation, demonstrating metabolic rescue of neuronal proteotoxicity downstream of protein aggregates. Our study highlights the involvement of small metabolites in the gut-brain interaction in neurodegenerative diseases.

The severity assessment of Parkinson's disease based on plasma inflammatory factors and third ventricle width by transcranial sonography

BACKGROUND

Predicting Parkinson's disease (PD) can provide patients with targeted therapies. However, disease severity can be roughly evaluated in clinical practice based on the patient's symptoms and signs.

OBJECTIVE

The current study attempted to explore the factors linked with PD severity and construct a predictive model.

METHOD

The PD patients and healthy controls were recruited from our study center while recording their basic demographic information. The serum inflammatory markers levels, such as Cystatin C (Cys C), C-reactive protein (CRP), RANTES (regulated on activation, normal T cell expressed and secreted), Interleukin-10 (IL-10), and Interleukin-6 (IL-6) were determined for all the participants. PD patients were categorized into early and mid-advanced groups based on the Hoehn and Yahr (H-Y) scale and evaluated using PD-related scales. LASSO logistic regression analysis (Model C) helped select variables based on clinical scale evaluations, serum inflammatory factor levels, and transcranial sonography measurements. The optimal harmonious model coefficient λ was determined via 10-fold cross-validation. Moreover, Model C was compared with multivariate (Model A) and stepwise (Model B) logistic regression. The area under the curve (AUC) of a receiver operator characteristic (ROC), brier score, calibration curve, and decision curve analysis (DCA) helped determine the discrimination and calibration of the predictive model, followed by configuring a forest plot and column chart.

RESULTS

The study included 113 healthy individuals and 102 PD patients, with 26 early and 76 mid-advanced patients. Univariate analysis of variance screened out statistically significant differences among inflammatory markers Cys C and RANTES. The average Cys C level in the mid-advanced stage was significantly higher than in the early stage (p < 0.001) but not for RANTES (p = 0.740). The LASSO logistic regression model (λ.1se = 0.061) associated with UPDRS-I, UPDRS-II, UPDRS-III, HAMA, PDQ-39, and Cys C as the included independent variables revealed that the Model C discrimination and calibration (AUC = 0.968, Brier = 0.049) were superior to Model A (AUC = 0.926, Brier = 0.079) and Model B (AUC = 0.929, Brier = 0.071) models.

CONCLUSION

The study results show multiple factors are linked with PD assessment. Moreover, the inflammatory marker Cys C and transcranial sonography measurement could objectively predict PD symptom severity, helping doctors monitor PD evolution in patients while targeting interventions.

Gut Symptoms, Gut Dysbiosis and Gut-Derived Toxins in ALS

Many pathogenetic mechanisms have been proposed for amyotrophic lateral sclerosis (ALS). Recently, there have been emerging suggestions of a possible role for the gut microbiota. Gut microbiota have a range of functions and could influence ALS by several mechanisms. Here, we review the possible role of gut-derived neurotoxins/excitotoxins. We review the evidence of gut symptoms and gut dysbiosis in ALS. We then examine a possible role for gut-derived toxins by reviewing the evidence that these molecules are toxic to the central nervous system, evidence of their association with ALS, the existence of biochemical pathways by which these molecules could be produced by the gut microbiota and existence of mechanisms of transport from the gut to the blood and brain. We then present evidence that there are increased levels of these toxins in the blood of some ALS patients. We review the effects of therapies that attempt to alter the gut microbiota or ameliorate the biochemical effects of gut toxins. It is possible that gut dysbiosis contributes to elevated levels of toxins and that these could potentially contribute to ALS pathogenesis, but more work is required.

Applications of Raman spectroscopy in the diagnosis and monitoring of neurodegenerative diseases

Raman scattering is an inelastic light scattering that occurs in a manner reflective of the molecular vibrations of molecular structures and chemical conditions in a given sample of interest. Energy changes in the scattered light can be assessed to determine the vibration mode and associated molecular and chemical conditions within the sample, providing a molecular fingerprint suitable for sample identification and characterization. Raman spectroscopy represents a particularly promising approach to the molecular analysis of many diseases owing to clinical advantages including its instantaneous nature and associated high degree of stability, as well as its ability to yield signal outputs corresponding to a single molecule type without any interference from other molecules as a result of its narrow peak width. This technology is thus ideally suited to the simultaneous assessment of multiple analytes. Neurodegenerative diseases represent an increasingly significant threat to global public health owing to progressive population aging, imposing a severe physical and social burden on affected patients who tend to develop cognitive and/or motor deficits beginning between the ages of 50 and 70. Owing to a relatively limited understanding of the etiological basis for these diseases, treatments are lacking for the most common neurodegenerative diseases, which include Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. The present review was formulated with the goal of briefly explaining the principle of Raman spectroscopy and discussing its potential applications in the diagnosis and evaluation of neurodegenerative diseases, with a particular emphasis on the research prospects of this novel technological platform.

2,5-Dihydroxyterephthalic Acid: A Matrix for Improved Detection and Imaging of Amino Acids

Amino acids (AAs), which are low-molecular-weight (low-MW) metabolites, serve as essential building blocks not only for protein synthesis but also for maintaining the nitrogen balance in living systems. In situ detection and imaging of AAs are crucial for understanding more complex biological processes. Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) is a label-free mass spectrometric imaging technique that enables the simultaneous detection and imaging of the spatial distribution and relative abundance of different endogenous/exogenous compounds in biological samples. The excellent efficiency of MALDI-MSI is attributed to the choice of the MALDI matrix. However, to the best of our knowledge, no matrix has been specifically developed for AAs. Herein, we report a MALDI matrix, 2,5-dihydroxyterephthalic acid (DHT), which can improve the detection and imaging of AAs in biological samples by MALDI-MS. Our results indicated that DHT exhibited strong ultraviolet-visible (UV-vis) absorption, uniform matrix deposition, and high vacuum stability. Moreover, the matrix-related ion signals produced from DHT were reduced by 50 and 71.8% at m/z < 500 compared to the commonly used matrices of 2,5-dihydroxybenzoic acid (DHB) and α-cyano-4-hydroxycinnamic acid (CHCA), respectively, in their respective organic solvents. In terms of quantitative performance, arginine, glutamic acid, glutamine, and proline can be detected with limits of detection of 6, 4, 6, and 4 ng/mL, respectively, using the DHT as the matrix. Using DHT as the matrix, all 20 protein AAs were successfully detected in human serum by MALDI-MS, whereas only 7 and 10 AAs were detected when DHB and CHCA matrices were used, respectively. Furthermore, 20 protein AAs and taurine were successfully detected and imaged in a section of edible Crassostrea gigas (oyster) tissue for the first time. Our study demonstrates that using DHT as a matrix can improve the detection and imaging of AAs in biological samples by MALDI-MS.

The Implication of a Polymorphism in the Methylenetetrahydrofolate Reductase Gene in Homocysteine Metabolism and Related Civilisation Diseases

Methylenetetrahydrofolate reductase (MTHFR) is a key regulatory enzyme in the one-carbon cycle. This enzyme is essential for the metabolism of methionine, folate, and RNA, as well as for the production of proteins, DNA, and RNA. MTHFR catalyses the irreversible conversion of 5,10-methylenetetrahydrofolate to its active form, 5-methyltetrahydrofolate, a co-substrate for homocysteine remethylation to methionine. Numerous variants of the MTHFR gene have been recognised, among which the C677T variant is the most extensively studied. The C677T polymorphism, which results in the conversion of valine to alanine at codon 222, is associated with reduced activity and an increased thermolability of the enzyme. Impaired MTHFR efficiency is associated with increased levels of homocysteine, which can contribute to increased production of reactive oxygen species and the development of oxidative stress. Homocysteine is acknowledged as an independent risk factor for cardiovascular disease, while chronic inflammation serves as the common underlying factor among these issues. Many studies have been conducted to determine whether there is an association between the C677T polymorphism and an increased risk of cardiovascular disease, hypertension, diabetes, and overweight/obesity. There is substantial evidence supporting this association, although several studies have concluded that the polymorphism cannot be reliably used for prediction. This review examines the latest research on MTHFR polymorphisms and their correlation with cardiovascular disease, obesity, and epigenetic regulation.

Transsulfuration pathway: a targeting neuromodulator in Parkinson's disease

The transsulfuration pathway (TSP) is a metabolic pathway involving sulfur transfer from homocysteine to cysteine. Transsulfuration pathway leads to many sulfur metabolites, principally glutathione, H2S, taurine, and cysteine. Key enzymes of the TSP, such as cystathionine β-synthase and cystathionine γ-lyase, are essential regulators at multiple levels in this pathway. TSP metabolites are implicated in many physiological processes in the central nervous system and other tissues. TSP is important in controlling sulfur balance and optimal cellular functions such as glutathione synthesis. Alterations in the TSP and related pathways (transmethylation and remethylation) are altered in several neurodegenerative diseases, including Parkinson's disease, suggesting their participation in the pathophysiology and progression of these diseases. In Parkinson's disease many cellular processes are comprised mainly those that regulate redox homeostasis, inflammation, reticulum endoplasmic stress, mitochondrial function, oxidative stress, and sulfur content metabolites of TSP are involved in these damage processes. Current research on the transsulfuration pathway in Parkinson's disease has primarily focused on the synthesis and function of certain metabolites, particularly glutathione. However, our understanding of the regulation of other metabolites of the transsulfuration pathway, as well as their relationships with other metabolites, and their synthesis regulation in Parkinson´s disease remain limited. Thus, this paper highlights the importance of studying the molecular dynamics in different metabolites and enzymes that affect the transsulfuration in Parkinson's disease.

Methylenetetrahydrofolate reductase polymorphisms in dental caries-induced pulp inflammation and regeneration of dentine-pulp complex: Future perspectives

Dental caries (DC)-induced pulp infections usually undergo the common endodontic treatment, root canal therapy (RCT). Endodontically treated teeth are devitalized, become brittle and susceptible for re-infection which eventually results in dental loss. These complications arise because the devitalized pulp losses its ability for innate homeostasis, repair and regeneration. Therefore, restoring the vitality, structure and function of the inflamed pulp and compromised dentin have become the focal points in regenerative endodontics. There are very few evidences, so far, that connect methylenetetrahydrofolate reductase single nucleotide polymorphisms (MTHFR-SNPs) and dental disorders. However, the primary consequences of MTHFR-SNPs, in terms of excessive homocysteine and folate deficiency, are well-known contributors to dental diseases. This article identifies the possible mechanisms by which MTHFR-SNP-carriers are susceptible for DC-induced pulp inflammation (PI); and discusses a cell-homing based strategy for in vivo transplantation in an orthotopic model to regenerate the functional dentine-pulp complex which includes dentinogenesis, neurogenesis and vasculogenesis, in the SNP-carriers.

Homocysteine, vitamin B metabolites, dopamine-substituting compounds, and symptomatology in Parkinson's disease: clinical and therapeutic considerations

Emerging studies suggest a correlation between elevated plasma homocysteine (hcy) levels and the risk of atherosclerosis, vascular disorders, and neurodegenerative diseases, including Parkinson's disease (PD). This narrative review delves into the intricate relationships between Hcy, vitamin B metabolites, dopamine-substituting compounds, and various symptoms of PD. Patients undergoing a long-term L-dopa/dopa-decarboxylase inhibitor (DDI) regimen, especially without a concurrent catechol-O-methyl transferase (COMT) inhibitor or methyl group-donating vitamin supplementation, such as vitamins B6 and B12, exhibit an elevation in Hcy and a decline in vitamin B metabolites. These altered concentrations appear to be associated with heightened risks of developing non-motor symptoms, including peripheral neuropathy and cognitive disturbances. The review underscores the impact of levodopa metabolism via COMT on homocysteine levels. In light of these findings, we advocate for the supplementation of methyl group-donating vitamins, notably B6 and B12, in patients undergoing a high-dose L-dopa/DDI regimen, particularly those treated with L-dopa/carbidopa intestinal gel (LCIG) infusion.

MDMA targets miR-124/MEKK3 via MALAT1 to promote Parkinson's disease progression

BACKGROUND

Parkinson's disease (PD) is a well-known neurodegenerative disease that is usually caused by the progressive loss of dopamine neurons and the formation of Lewy vesicles. 3,4-Methylenedioxymethamphetamine (MDMA) has been reported to cause damage to human substantia nigra neurons and an increased risk of PD, but the exact molecular mechanisms need further investigation.

METHODS

MPTP- and MPP+-induced PD cells and animal models were treated with Nissl staining to assess neuronal damage in the substantia nigra (SN) area; immunohistochemistry to detect TH expression in the SN; TUNEL staining to detect apoptosis in the SN area; Western blotting to detect the inflammatory factors NF-κB, TNF-α, IL-6 and mitogen-activated protein kinase kinase kinase 3 (MEKK3); Griess assay for NO; RT‒qPCR for metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) and miR-124 expression; Cell proliferation was assessed by CCK-8. Dual luciferase reporter genes were used to verify targeting relationships.

RESULTS

MDMA promoted MALAT1 expression, and knockdown of MALAT1 alleviated the MDMA-induced inhibition of SH-SY5Y cell proliferation, inflammation, NO release, SN neuronal injury, and TH expression inhibition. Both inhibition of miR-124 and overexpression of MEKK3 reversed the neuroprotective effects exhibited by knockdown of MALAT1.

CONCLUSION

MDMA promotes MALAT1 expression and inhibits the targeted downregulation of MEKK3 by miR-124, resulting in upregulation of the expression of MEKK3 and finally jointly promoting PD progression.

Defective quality control autophagy in Hyperhomocysteinemia promotes ER stress and consequent neuronal apoptosis through proteotoxicity

Homocysteine (Hcy), produced physiologically in all cells, is an intermediate metabolite of methionine and cysteine metabolism. Hyperhomocysteinemia (HHcy) resulting from an in-born error of metabolism that leads to accumulation of high levels of Hcy, is associated with vascular damage, neurodegeneration and cognitive decline. Using a HHcy model in neuronal cells, primary cortical neurons and transgenic zebrafish, we demonstrate diminished autophagy and Hcy-induced neurotoxicity associated with mitochondrial dysfunction, fragmentation and apoptosis. We find this mitochondrial dysfunction is due to Hcy-induced proteotoxicity leading to ER stress. We show this sustained proteotoxicity originates from the perturbation of upstream autophagic pathways through an aberrant activation of mTOR and that protetoxic stress act as a feedforward cues to aggravate a sustained ER stress that culminate to mitochondrial apoptosis in HHcy model systems. Using chemical chaperones to mitigate sustained ER stress, Hcy-induced proteotoxicity and consequent neurotoxicity were rescued. We also rescue neuronal lethality by activation of autophagy and thereby reducing proteotoxicity and ER stress. Our findings pave the way to devise new strategies for the treatment of neural and cognitive pathologies reported in HHcy, by either activation of upstream autophagy or by suppression of downstream ER stress. Video Abstract.

Multidimensional biomarkers for multiple system atrophy: an update and future directions

Multiple system atrophy (MSA) is a fatal progressive neurodegenerative disease. Biomarkers are urgently required for MSA to improve the diagnostic and prognostic accuracy in clinic and facilitate the development and monitoring of disease-modifying therapies. In recent years, significant research efforts have been made in exploring multidimensional biomarkers for MSA. However, currently few biomarkers are available in clinic. In this review, we systematically summarize the latest advances in multidimensional biomarkers for MSA, including biomarkers in fluids, tissues and gut microbiota as well as imaging biomarkers. Future directions for exploration of novel biomarkers and promotion of implementation in clinic are also discussed.

Bioinorganic Chemistry of Micronutrients Related to Alzheimer's and Parkinson's Diseases

Metal ions are fundamental to guarantee the regular physiological activity of the human organism. Similarly, vitamins play a key role in many biological functions of the metabolism, among which are coenzymes, redox mediators, and antioxidants. Due to their importance in the human organism, both metals and vitamins have been extensively studied for their involvement in neurodegenerative diseases (NDs). However, the full potential of the interaction between vitamins and metal ions has not been fully explored by researchers yet, and further investigation on this topic is needed. The aim of this review is to provide an overview of the scientific literature on the implications of vitamins and selected metal ions in two of the most common neurodegenerative diseases, Alzheimer's and Parkinson's disease. Furthermore, vitamin-metal ion interactions are discussed in detail focusing on their bioinorganic chemistry, with the perspective of arousing more interest in this fascinating bioinorganic field.

Vitamin B₁₂ deficiency and Parkinson’s disease

Parkinson’s disease (PD) is a progressive neurodegenerative disease with various clinical manifestations, its origin not always can be explained only by dopamine deficiency. Long-term treatment with levodopa (especially its intraduodenal administration), as well as clinical manifestations of polyneuropathy, cognitive deficits, postural disorders with freezing of gate, REM sleep behavioral disorders, are more often associated with vitamin B12 deficiency. Several reasons for this association and mechanisms of their development are discussed. Early detection of cobalamin deficiency in PD, especially in patients from high-risk groups, makes it possible to stop this pathological condition timely and prevent irreversible changes. Modern data on the use of high-dose (1000 μ g) oral vitamin B12 are presented, it has comparable clinical efficacy and significant advantages, compared with the parenteral form, in terms of the ease of use and the ability to avoid undesirable postinjection reactions.

Selected Biomarkers of Oxidative Stress and Energy Metabolism Disorders in Neurological Diseases

Neurological diseases can be broadly divided according to causal factors into circulatory system disorders leading to ischemic stroke; degeneration of the nerve cells leading to neurodegenerative diseases, such as Alzheimer's (AD) and Parkinson's (PD) diseases, and immune system disorders; bioelectric activity (epileptic) problems; and genetically determined conditions as well as viral and bacterial infections developing inflammation. Regardless of the cause of neurological diseases, they are usually accompanied by disturbances of the central energy in a completely unexplained mechanism. The brain makes up only 2% of the human body's weight; however, while working, it uses as much as 20% of the energy obtained by the body. The energy requirements of the brain are very high, and regulatory mechanisms in the brain operate to ensure adequate neuronal activity. Therefore, an understanding of neuroenergetics is rapidly evolving from a "neurocentric" view to a more integrated picture involving cooperativity between structural and molecular factors in the central nervous system. This article reviewed selected molecular biomarkers of oxidative stress and energy metabolism disorders such as homocysteine, DNA damage such as 8-oxo2dG, genetic variants, and antioxidants such as glutathione in selected neurological diseases including ischemic stroke, AD, PD, and epilepsy. This review summarizes our and others' recent research on oxidative stress in neurological disorders. In the future, the diagnosis and treatment of neurological diseases may be substantially improved by identifying specific early markers of metabolic and energy disorders.

Homocysteine-Potential Novel Diagnostic Indicator of Health and Disease in Horses

Homocysteine is an endogenous, non-protein sulfuric amino acid, an intermediate metabolite formed by the methionine transmethylation reaction. Its elevated serum concentration in humans, hyperhomocysteinemia, is a sensitive indicator and a risk factor for coagulation disorders, cardiovascular diseases and dementia. However, the role of homocysteine in veterinary species has not been unequivocally established. Although some research has been conducted in dogs, cats, cattle and pigs, relatively few studies on homocysteine have been conducted in horses. So far, it has been established in this species that homocysteine has an atherogenic effect, plays a role in early embryo mortality and is responsible for the induction of oxidative stress. These preliminary findings support establishing a reference range in a normal population of horses, including horses in training and merit further investigations into the role of this amino acid in health and disease in this species.

Controlling the Impact of Helicobacter pylori-Related Hyperhomocysteinemia on Neurodegeneration

Helicobacter pylori infection consists a high global burden affecting more than 50% of the world’s population. It is implicated, beyond substantiated local gastric pathologies, i.e., peptic ulcers and gastric cancer, in the pathophysiology of several neurodegenerative disorders, mainly by inducing hyperhomocysteinemia-related brain cortical thinning (BCT). BCT has been advocated as a possible biomarker associated with neurodegenerative central nervous system disorders such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, and/or glaucoma, termed as “ocular Alzheimer’s disease”. According to the infection hypothesis in relation to neurodegeneration, Helicobacter pylori as non-commensal gut microbiome has been advocated as trigger and/or mediator of neurodegenerative diseases, such as the development of Alzheimer’s disease. Among others, Helicobacter pylori-related inflammatory mediators, defensins, autophagy, vitamin D, dietary factors, role of probiotics, and some pathogenetic considerations including relevant involved genes are discussed within this opinion article. In conclusion, by controlling the impact of Helicobacter pylori-related hyperhomocysteinemia on neurodegenerative disorders might offer benefits, and additional research is warranted to clarify this crucial topic currently representing a major worldwide burden.

Metabolomic Footprint of Disrupted Energetics and Amino Acid Metabolism in Neurodegenerative Diseases: Perspectives for Early Diagnosis and Monitoring of Therapy

The prevalence of neurodegenerative diseases (NDs) is increasing due to the aging population and improved longevity. They are characterized by a range of pathological hallmarks, including protein aggregation, mitochondrial dysfunction, and oxidative stress. The aim of this review is to summarize the alterations in brain energy and amino acid metabolism in Alzheimer’s disease (AD), Parkinson’s disease (PD), and Huntington’s disease (HD). Based on our findings, we proposed a group of selected metabolites related to disturbed energy or mitochondrial metabolism as potential indicators or predictors of disease. We also discussed the hidden challenges of metabolomics studies in NDs and proposed future directions in this field. We concluded that biochemical parameters of brain energy metabolism disruption (obtained with metabolomics) may have potential application as a diagnostic tool for the diagnosis, prediction, and monitoring of the effectiveness of therapies for NDs. However, more studies are needed to determine the sensitivity of the proposed candidates. We suggested that the most valuable biomarkers for NDs studies could be groups of metabolites combined with other neuroimaging or molecular techniques. To attain clinically applicable results, the integration of metabolomics with other “omic” techniques might be required.

Two Faces of Catechol-O-Methyltransferase Inhibitor on One-Carbon Metabolism in Parkinson's Disease: A Meta-Analysis

Levodopa (L-dopa) and catechol-O-methyltransferase (COMT) inhibition are widely used therapeutics in Parkinson's disease (PD). Despite their therapeutic effects, it was raised that nutrients involved in one-carbon metabolism can be deteriorated by PD therapies. The aim of this meta-analysis was to investigate the impact of L-dopa and COMT inhibitors on levels of homocysteine (Hcy), vitamin B₁₂ and folate in patients with PD. A total of 35 case-control studies from 14 different countries were selected through PubMed, MEDLINE and Google Scholar and were meta-analyzed. In the L-dopa group, the Hcy level was higher compared to the PD without L-dopa group (SMD: 5.11 μmol/L, 95% CI: 3.56 to 6.66). Moreover, vitamin B₁₂ and folate levels in the L-dopa group were lower compared to the healthy control (SMD: -62.67 pg/mL, 95% CI: -86.53 to -38.81; SMD: -0.89 ng/mL, 95% CI: -1.44 to -0.33, respectively). The COMT inhibitor group showed lower levels of Hcy (SMD: -3.78 μmol/L, 95% CI: -5.27 to -2.29) and vitamin B₁₂ (SMD: -51.01 pg/mL, 95% CI: -91.45 to -10.57), but higher folate levels (SMD: 1.78 ng/mL, 95% CI: -0.59 to 4.15) compared to the L-dopa group. COMT inhibitors may ameliorate L-dopa-induced hyper-homocysteine and folate deficiency but exacerbate vitamin B₁₂ deficiency.

Profiling of Homocysteine Metabolic Pathway Related Metabolites in Plasma of Diabetic Mellitus Based on LC-QTOF-MS

Background: Homocysteine (Hcy) has been found to be closely related to the occurrence of diabetes mellitus (DM) and is considered as one of the risk factors of DM. However, Hcy alone is not enough as a factor to predict DM, and our study analyzed and determined the relationship between the main metabolites involved in the Hcy metabolic pathway and DM. Methods: A total of 48 clinical samples were collected, including 18 health control samples and 30 DM samples. All standards and samples were detected by LC-QTOF-MS. Multivariate statistical analysis and k-means cluster analysis were performed to screen and confirm the metabolites significantly correlated with DM. Results: A total of 13 metabolites of the Hcy metabolic pathway were detected in the samples. The content of Hcy, cysteine, taurine, pyridoxamine, methionine, and choline were significantly increased in the DM group (p < 0.05). Hcy, choline, cystathionine, methionine, and taurine contributed significantly to the probabilistic principal component analysis (PPCA) model. The odds ratios (OR) of Hcy, cysteine, taurine, methionine, and choline were all greater than one. K-means cluster analysis showed that the Hcy, taurine, methionine, and choline were significantly correlated with the distribution of glucose values (divided into four levels: 10.5−11.7 mmol/L, 7.7−9.7 mmol/L, 6.0−6.9 mmol/L, and 5.0−5.9 mmol/L, respectively). Conclusion: Hcy, taurine, methionine, and choline can be used as risk factors for diabetes diagnosis and are expected to be used for the assessment of diabetes severity.

Homocysteine levels, genetic background, and cognitive impairment in Parkinson's disease

BACKGROUND

Hyperhomocysteinemia is considered an independent risk factor for cognitive impairment.

OBJECTIVE

To study the correlation between homocysteine levels and cognitive impairment in patients with PD.

METHODS

We conducted a case-control study that included 246 patients with PD, of whom 32 were cognitively impaired. The levels of homocysteine, folate, and vitamin B12 were measured in peripheral blood. Multivariate logistic regression analysis was applied to determine differences in homocysteine levels between PD patients with and without cognitive impairment. A meta-analysis was performed to clarify the role of Hcy levels in PD with cognitive decline. Five polymorphisms in genes involved in Hcy metabolism, including MTHFR rs1801133 and rs1801131, COMT rs4680, MTRR rs1801394, and TCN2 rs1801198, were genotyped.

RESULTS

Our case-control study showed that homocysteine levels were associated with cognitive impairment in PD after adjusting for possible confounding factors such as levodopa equivalent daily dose. The results of our meta-analysis further supported the positive association between homocysteine levels and cognition in PD. We found that the MTHFR rs1801133 TT genotype led to higher homocysteine levels in PD patients, whereas the MTHFR rs1801131 CC genotype resulted in higher folate levels. However, the polymorphisms studied were not associated with cognitive impairment in PD.

CONCLUSIONS

Increased homocysteine levels were a risk factor for cognitive decline in PD. However, no association was found between polymorphisms in genes involved in homocysteine metabolism and cognitive impairment in PD. Large-scale studies of ethnically diverse populations are required to definitively assess the relationship between MTHFR and cognitive impairment in PD.

Quantitative and causal analysis for inflammatory genes and the risk of Parkinson's disease

Background

The dysfunction of immune system and inflammation contribute to the Parkinson's disease (PD) pathogenesis. Cytokines, oxidative stress, neurotoxin and metabolism associated enzymes participate in neuroinflammation in PD and the genes involved in them have been reported to be associated with the risk of PD. In our study, we performed a quantitative and causal analysis of the relationship between inflammatory genes and PD risk.

Methods

Standard process was performed for quantitative analysis. Allele model (AM) was used as primary outcome analysis and dominant model (DM) and recessive model (RM) were applied to do the secondary analysis. Then, for those genes significantly associated with the risk of PD, we used the published GWAS summary statistics for Mendelian Randomization (MR) to test the causal analysis between them.

Results

We included 36 variants in 18 genes for final pooled analysis. As a result, IL-6 rs1800795, TNF-α rs1799964, PON1 rs854560, CYP2D6 rs3892097, HLA-DRB rs660895, BST1 rs11931532, CCDC62 rs12817488 polymorphisms were associated with the risk of PD statistically with the ORs ranged from 0.66 to 3.19 while variants in IL-1α, IL-1β, IL-10, MnSOD, NFE2L2, CYP2E1, NOS1, NAT2, ABCB1, HFE and MTHFR were not related to the risk of PD. Besides, we observed that increasing ADP-ribosyl cyclase (coded by BST1) had causal effect on higher PD risk (OR[95%CI] =1.16[1.10-1.22]) while PON1(coded by PON1) shown probably protective effect on PD risk (OR[95%CI] =0.81[0.66-0.99]).

Conclusion

Several polymorphisms from inflammatory genes of IL-6, TNF-α, PON1, CYP2D6, HLA-DRB, BST1, CCDC62 were statistically associated with the susceptibility of PD, and with evidence of causal relationships for ADP-ribosyl cyclase and PON1 on PD risk, which may help understand the mechanisms and pathways underlying PD pathogenesis.

Analysis of Clinical Characteristics and Influencing Factors for H-Type Hypertension Complicated with Other Chronic Diseases in a Community in Beijing

Objective. The aim of the study is to analyze the clinical characteristics of patients with H-type hypertension complicated with other chronic diseases in a community in Beijing and to explore the influencing factors related to the occurrence of the disease by means of a case-control study. Methods. A questionnaire was designed. 362 residents with H-type hypertension in a community in Beijing were randomly enrolled from January 2020 to December 2021. The general data and clinical indexes of the patients were collected and their clinical characteristics were analyzed. According to the complications of other chronic diseases, they were divided into the simple hypertension group (n = 65) and the other chronic disease group (n = 297). Univariate and multivariate analyses were used to analyze the influencing factors for H-type hypertension patients with other chronic diseases. Results. Among the 362 H-type hypertension patients, 21 cases were aged 35–45 years, 35 cases were aged 45–55 years, and 127 cases were aged 55–65 years. The number of patients aged ≥65 years was 179, and the number of patients aged ≥55 years accounted for the highest proportion with a constituent ratio of 85.00%. Only 65 patients were patients with simple hypertension. The remaining 297 patients were complicated with different kinds of chronic diseases. The types of chronic diseases include malignant tumors, diabetes, rheumatoid arthritis, coronary heart disease, asthma, chronic obstructive pulmonary disease, systemic lupus erythematosus, and stroke. The proportion of H-type hypertension complicated with coronary heart disease, diabetes, and stroke is higher. Among the 297 patients, most of them were local, resident, and nonagricultural patients with a constituent ratio of 89.90%, 95.96%, and 98.98%, respectively. The prevalence rate of the male was 59.60% higher than that of the female at 40.40%. The blood types B and AB were more common. 90.57% of patients were married and the proportion of body mass index (BMI) was 45.79%. 60.61% of patients had a history of smoking, 55.56% had a history of drinking, 35.02% had a regular physical examination, 14.81% had regular exercise, and 37.71% had a light diet. There were significant differences in marital status, smoking, alcohol consumption, regular exercise, and light diet between the simple hypertension group and the chronic disease group ( $P<0.05$ ). The results of the logistic regression analysis showed that smoking, drinking, little exercise, and not eating lightly were the independent risk factors for other chronic diseases ( $P<0.05$ ). Conclusion. The incidence of H-type hypertension is higher in people ≥55 years old. Most of them are accompanied by three other chronic diseases: smoking, drinking, little exercise, and no light diet are also risk factors for chronic diseases.

The microbiome-gut-brain axis in Parkinson disease - from basic research to the clinic

Evidence for a close bidirectional link between the brain and the gut has led to a paradigm shift in neurology, especially in the case of Parkinson disease (PD), in which gastrointestinal dysfunction is a prominent feature. Over the past decade, numerous high-quality preclinical and clinical publications have shed light on the highly complex relationship between the gut and the brain in PD, providing potential for the development of new biomarkers and therapeutics. With the advent of high-throughput sequencing, the role of the gut microbiome has been specifically highlighted. Here, we provide a critical review of the literature on the microbiome-gut-brain axis in PD and present perspectives that will be useful for clinical practice. We begin with an overview of the gut-brain axis in PD, including the potential roles and interrelationships of the vagus nerve, α-synuclein in the enteric nervous system, altered intestinal permeability and inflammation, and gut microbes and their metabolic activities. The sections that follow synthesize the proposed roles of gut-related factors in the development and progression of, in responses to PD treatment, and as therapeutic targets. Finally, we summarize current knowledge gaps and challenges and delineate future directions for the field.

Does Parkinson's disease affect peripheral circulation and vascular function in physically active patients?

Previous studies demonstrated that aging, neurodegeneration, and the level of physical activity are associated with vascular alterations. However, in Parkinson's disease (PD) only cerebral vascular function has been investigated; instead, the contribution of PD on systemic vascular function and skeletal muscle circulation remains a matter of debate. In this study, the hyperemic response during the single passive leg movement test (sPLM), largely nitric oxide dependent, was examined at the level of the common femoral artery with an ultrasound Doppler system to assess systemic vascular function in 10 subjects with PD (PDG), compared with 10 aged-sex and physically active matched healthy elderly (EHG), and 10 physically active young healthy individuals (YHG). Interestingly, femoral blood flow at rest, normalized for the thigh volume, was similar in PDG (64±15 mL min^-1 L^-1), EHG (44±8 mL min^-1 L^-1) and YHG (58±11 mL min^-1 L^-1, all p > 0.05). The sPLM-induced hyperemic response appeared markedly lower in PDG and EHG compared to YHG (8.3±0.1 vs 9.8±0.8 vs 17.3±3.0 mL min^-1 L^-1; p < 0.05) but the difference between PDG and EHG was negligible (p > 0.05). The results of our study indicate that peripheral circulation and vascular function are not reduced in physically active patients with PD, suggesting that these vascular changes could resemble the physiological adjustments of aging, without any impact from the disease.

Elevation of Plasma Homocysteine and Minor Hallucinations in Parkinson’s Disease: A Cross-Sectional Study

Purpose

Minor hallucinations (MHs) are the most common psychotic phenomena in Parkinson's disease (PD), and it has important clinical and prognostic implications in PD. Plasma homocysteine (Hcy) has been reported to predict the outcome of PD; whether or not Hcy is associated with MH is not known. We aim to investigate the Hcy level and related factors in patients with PD and MH.

Methods

We conducted a cross-sectional study and included 99 patients with PD, 34 with MH, and 65 without any hallucinations. The clinical and demographic data of the patients with and without hallucinations were compared. Hcy-related clinical factors were also analyzed.

Results

The plasma Hcy level was higher in MH patients than in patients without hallucinations, and the result was more pronounced in male patients than in female patients. Differences were also observed when the groups were divided on the basis of levodopa equivalent daily dose and disease duration. The high Hcy concentration was correlated with some symptoms in patients with MH, including motor dysfunction and nonmotor symptoms, such as symptoms of the gastrointestinal tract, angiocarpy, sleep/fatigue, and poor visuospatial/executive function.

Conclusions

Results indicated a higher plasma Hcy concentration in MH patients than in their counterparts and revealed that Hcy is associated with certain motor and nonmotor symptoms in patients with MH. Hcy may be a marker of MH and have important therapeutic implications in PD.

Spontaneous posterior dislocation of the cataractous lens in a patient with Parkinson-plus syndrome

Purpose

To report a case of unilateral posterior dislocation of the cataractous lens and subluxation of the lens in the fellow eye of a patient with Parkinson-plus syndrome.

Observations

A 67-year-old-man who was a known case of Parkinson-plus syndrome on long-term dopamine agonists and anti-psychotic medications demonstrated apraxia of lid opening associated with moderate-to-severe blepharospasm. He had unilateral posterior dislocation of the cataractous lens and subluxation of the lens in the fellow eye with no prior history of trauma or other known ocular risk factors.

Conclusion and importance

This case may represent an unusual example of spontaneous lens dislocation secondary to apraxia of lid opening and concurrent blepharospasm, which is associated with Parkinson-plus syndrome.

One-Carbon Metabolism: Pulling the Strings behind Aging and Neurodegeneration

One-carbon metabolism (OCM) is a network of biochemical reactions delivering one-carbon units to various biosynthetic pathways. The folate cycle and methionine cycle are the two key modules of this network that regulate purine and thymidine synthesis, amino acid homeostasis, and epigenetic mechanisms. Intersection with the transsulfuration pathway supports glutathione production and regulation of the cellular redox state. Dietary intake of micronutrients, such as folates and amino acids, directly contributes to OCM, thereby adapting the cellular metabolic state to environmental inputs. The contribution of OCM to cellular proliferation during development and in adult proliferative tissues is well established. Nevertheless, accumulating evidence reveals the pivotal role of OCM in cellular homeostasis of non-proliferative tissues and in coordination of signaling cascades that regulate energy homeostasis and longevity. In this review, we summarize the current knowledge on OCM and related pathways and discuss how this metabolic network may impact longevity and neurodegeneration across species.

Opicapone Protects Against Hyperhomocysteinemia-Induced Increase in Blood-Brain Barrier Permeability

Hyperhomocysteinemia (HHcy)-related brain vascular disorders and brain endothelial dysfunction are important characteristics of the pathogeneses of subarachnoid hemorrhage and stroke. Upregulated homocysteine (Hcy) can impair the integrity of the blood-brain barrier (BBB). Opicapone has been recently licensed for the management of Parkinson's disease (PD); however, it is unknown whether it possesses a protective effect in brain vessels against HHcy. To investigate the beneficial effects of Opicapone on BBB permeability against HHcy, we carried out both in vivo and in vitro experiments. Mice were allocated into four groups: the Control, Opicapone, HHcy, and HHcy + Opicapone. Interestingly, we found that the administration of Opicapone attenuated the increased BBB permeability in Hcy-treated mice, as determined by sodium fluorescein staining. The immunofluorescence staining showed that Opicapone prevented homocysteine-induced reduction of claudin-2 in the mice cortices. The in situ zymography assay revealed that Opicapone suppressed homocysteine-increased matrix metalloproteinases (MMPs) activity in the cortices. In bEnd.3 brain endothelial cells, Opicapone treatment ameliorated homocysteine-induced lactate dehydrogenase (LDH) release and expression of matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP-9). Furthermore, Opicapone alleviated homocysteine-induced decrease in claudin-2 level in bEnd.3 cells. In summary, our results show that Opicapone protects against HHcy-induced BBB permeability by reducing the expression and gelatinase activity of MMPs, and increasing the expression of claudin-2.