Homocysteine and Age-Related Central Nervous System Diseases: Role of Inflammation

Tectorigenin mitigates homocysteine-induced inflammation and ferroptosis in BV-2 microglial cells through promoting the SIRT1/SLC7A11 pathway

Ferroptosis and inflammation are central to the pathophysiology of hyperhomocysteinemia (HHcy)-associated neurological disorders. Tectorigenin, a natural flavonoid aglycone extracted from numerous plants, possesses antioxidant, anti-inflammatory, and neuroprotective properties. This study aimed to investigate whether tectorigenin mitigates elevated homocysteine (Hcy)-induced toxicity in BV-2 microglial cells, focusing on its effects on inflammation and ferroptosis. Cell viability, lactate dehydrogenase (LDH) release, and proliferation assays were employed to evaluate cell injury. Inflammatory cytokines levels were determined by ELISA. Ferroptosis markers, including reactive oxygen species (ROS), lipid ROS, malondialdehyde (MDA), 4-hydroxy-nonenal (4-HNE), mitochondrial membrane potential (MMP), ATP, Fe2 + content, antioxidant enzymes (superoxide dismutase [SOD] and catalase [CAT]) activities were evaluated. mRNA and protein expressions were analyzed by qRT-PCR and western blotting, respectively. Our findings revealed that tectorigenin pretreatment significantly alleviated Hcy-induced cell injury and inflammatory response in BV-2 microglial cells. Furthermore, tectorigenin pretreatment reduced lipid peroxidation, enhanced antioxidant capacity, and alleviated ferroptotic cell death in Hcy-treated cells. Importantly, ferroptosis inhibitor Fer-1 also alleviated Hcy-induced cell injury and inflammation. Mechanistically, tectorigenin pretreatment activated the SIRT1/SLC7A11 pathway, and silencing SIRT1 reversed its protective effects. Collectively, these results indicate that tectorigenin attenuates Hcy-induced microglial injury by inhibiting inflammation and ferroptosis through the activation of the SIRT1/SLC7A11 pathway.

Nicotinamide N-methyltransferase as a potential therapeutic target for neurodegenerative disorders: Mechanisms, challenges, and future directions

Neurodegenerative diseases (NDs), including Alzheimer's disease (AD), Parkinson's disease (PD), and Huntington's disease (HD), are characterized by progressive neuronal loss and functional decline, posing significant global health challenges. Emerging evidence highlights nicotinamide N-methyltransferase (NNMT), a cytosolic enzyme regulating nicotinamide (NAM) methylation, as a pivotal player in NDs through its dual impact on epigenetic regulation and metabolic homeostasis. This review synthesizes current knowledge on NNMT's role in disease pathogenesis, focusing on its epigenetic modulation via DNA hypomethylation and histone modifications, alongside its disruption of NAD+ synthesis and homocysteine (Hcy) metabolism. Elevated NNMT activity depletes NAD+, exacerbating mitochondrial dysfunction and impairing energy metabolism, while increased Hcy levels drive oxidative stress, neuroinflammation, and aberrant protein aggregation (e.g., Aβ, tau, α-synuclein). Notably, NNMT overexpression in AD and PD correlates with neuronal hypomethylation and neurotoxicity, as observed in postmortem brain studies and transgenic models. Mechanistically, NNMT consumes S-adenosylmethionine (SAM), limiting methyl donor availability for DNA methyltransferases (DNMTs) and histone methyltransferases (HMTs), thereby altering gene expression patterns critical for neuronal survival. Concurrently, NNMT-mediated NAD+ depletion disrupts sirtuin activity (e.g., SIRT1) and mitochondrial biogenesis, accelerating axonal degeneration. Therapeutic strategies targeting NNMT, such as RNA interference (RNAi), small-molecule inhibitors and exercise therapy, show promise in preclinical models by restoring NAD+ levels and reducing Hcy toxicity. However, challenges persist in achieving cellular specificity, optimizing blood-brain barrier penetration, and mitigating off-target effects. This review underscores NNMT's potential as a multifactorial therapeutic target, bridging metabolic and epigenetic dysregulation in NDs. Future research should prioritize elucidating tissue-specific NNMT interactions, refining inhibitor pharmacokinetics, and validating translational efficacy in clinical trials. Addressing these gaps could pave the way for novel disease-modifying therapies to combat the rising burden of neurodegeneration.

A cross-sectional observational study of the association between biochemistry profiles and the risk of age-related macular degeneration

This study aimed to explore the relationship between biochemical profiles and the risk of age-related macular degeneration (AMD) through a cross-sectional observational analysis. We examined data of U. S. population from the 2005-2008 National Health and Nutrition Examination Survey (NHANES) database. Student's t-test, multivariable logistic regression, Pearson's correlation, restricted cubic spline (RCS) model, and linear regression were applied to analyze the underlying relationship between biochemical profiles and the AMD risk, through comparing data between the non-AMD and AMD subgroups. Multivariable logistic regression, adjusted for age and demographic factors, showed no significant associations between the AMD risk and the levets of specific biochemical parameters (P > 0.05). Pearson's correlation revealed a positive linear relationship between age and total bilirubin, uric acid in the non-AMD subgroup (P < 0.05), but no such liner association was found in the AMD subgroup (P > 0.05). The RCS model confirmed no non-linear relationships presented between these variables in the AMD subgroup. In addition, without age adjustment, significant associations were found between total bilirubin, uric acid, and the AMD presence (P < 0.05). Biochemical profiles, after adjusting for age, did not significantly influence the AMD risk. However, total bilirubin and uric acid might potentially be related to the AMD presence. Our findings suggest a need for further research to clarify the role of these biomarkers in AMD development.

Serum homocysteine levels as a predictor of neurosyphilis among HIV-negative syphilis patients: A single-center retrospective study

This study investigates the differences in peripheral blood parameters between patients with non-neurosyphilis and neurosyphilis, aiming to identify potential serum biomarkers to predict the occurrence of neurosyphilis and avoid unnecessary lumbar punctures. A retrospective analysis was conducted on 110 HIV-negative syphilis patients in this study. We found that the serum homocysteine (Hcy) levels in the non-neurosyphilis group, asymptomatic neurosyphilis group, and symptomatic neurosyphilis group were 12.30 (10.45, 13.25), 17.50 (12.03, 26.28), and 15.70 (13.70, 20.20), respectively. The serum Hcy levels in the asymptomatic neurosyphilis group and symptomatic neurosyphilis group were significantly higher than those in the non-neurosyphilis group (P<0.05). The AUC for serum Hcy in diagnosing neurosyphilis was 0.861 (95% CI: 0.715-0.950), with a sensitivity and specificity of 98.47% and 71.43% respectively. The study indicated that serum Hcy levels serve as a potential biomarker to differentiate neurosyphilis from non-neurosyphilis.

Expression of Neuronal Nicotinic Acetylcholine Receptor and Early Oxidative DNA Damage in Aging Rat Brain-The Effects of Memantine

Aging and age-related neurodegenerative disorders are characterized by the dysfunction or loss of brain nicotinic acetylcholine receptors (nAChRs), and these changes may be related to other senescence markers, such as oxidative stress and DNA repair dysfunction. However, the mechanism of nAChR loss in the aging brain and the modification of this process by drugs (e.g., memantine, Mem) are not yet fully understood. To study whether the differences in nAChR expression in the rat brain occur due to aging or oxidative stress and are modulated by Mem, we analyzed nAChR subunits (at RNA and protein levels) and other biomarkers by real-time quantitative polymerase chain reaction (RQ-PCR) and Western blot validation. Twenty-one female Wistar rats were divided into four groups, depending on age, and the oldest group received injections of Mem or water with the use of intragastric catheters. We studied the cerebral grey matter (CGM), subcortical white matter (SCWM), and cerebellum (Ce). Results showed an age-related decrease of α7 nAChR mRNA level in SCWM. The α7 nAChR mRNA loss was accompanied by reduced expression of 8-oxoguanine DNA glycosylase 1 (OGG1) and an increased tumor necrosis factor alpha (TNFα) level. In the water group, we observed a higher level of α7 nAChR protein in the SCWM and Ce. Biomarker levels changed, but to a different extent depending on the brain area. Importantly, the dysfunction in antioxidative status was stopped and even regressed under Mem treatment. After two weeks of treatment, an increase in TP53 protein level and a decrease in 8-oxo-2'deoxyguanosine (8-oxo-2'dG) level were observed. We conclude that Mem administration may be protective against the senescence process by antioxidative mechanisms.

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.

CAMK2D and Complement Factor I-Involved Calcium/Calmodulin Signaling Modulates Sodium Iodate-Induced Mouse Retinal Degeneration

Purpose

To investigate the effect of Ca2+/calmodulin-dependent protein kinase II (CAMKII) δ subtypes (CAMK2D) on sodium iodate (NaIO3)-induced retinal degeneration in mice.

Methods

Bioinformatics analysis and Western blot experiments were used to screen the significantly differentially expressed genes in age-related macular degeneration (AMD) disease. CAMK2D knockdown and overexpression models were constructed by lentivirus (LV) infection of adult retinal pigment epithelial cell line-19 (ARPE-19) cells in vitro. Flow cytometry was used to detect ARPE-19 cell apoptosis induced by NaIO3. In vivo, CAMK2D knockdown and overexpression mouse models were generated by infecting mouse retinal pigment epithelium (RPE) with adeno-associated virus (AAV). Retinography, optical coherence tomography (OCT), and histological analysis (hematoxylin and eosin staining) were used to detect NaIO3-induced retinal structural changes in mice. Electroretinography (ERG) was used to detect NaIO3-induced retinal function changes in mice. TdT-mediated dUTP nick-end labeling (TUNEL) staining was used to detect the apoptosis of retinal cells induced by NaIO3. RNA sequencing (RNA-Seq) and bioinformatics analysis were used to screen for target genes affected by CAMK2D in CAMK2D-overexpressing ARPE-19 cells. And flow cytometry, OCT, and ERG were used to evaluate the regulatory effect of CAMK2D on target genes.

Results

Bioinformatics analysis found the expression of genes related to Ca2+ signal was significantly reduced in AMD patients. Western blot showed that in a mouse model of dry AMD induced by NaIO3, CAMK2D expression in RPE-Choroid tissue significantly lower than normal mice. In vitro, our results showed that overexpression of CAMK2D in ARPE-19 cells decreased apoptosis induced by NaIO3 and knockdown increased apoptosis. In vivo, CAMK2D overexpression in RPE cells can attenuate the retina degeneration induced by NaIO3 and CAMK2D knockdown aggravated degeneration. The bioinformatics analysis indicated that CAMK2D might affect AMD pathology through complement factor I (CFI). In vitro, knockdown of CFI in ARPE-19 cells increased apoptosis induced by NaIO3. In knockdown CFI ARPE-19 cells, overexpression of CAMK2D reduced the above apoptosis. In mice retina, CFI knockdown can aggravate the retina degeneration induced by NaIO3. In knockdown CFI mice, overexpression of CAMK2D in RPE can attenuate the above retina degeneration. Western blot confirmed that CAMK2D regulated the expression of CFI in mice.

Conclusions

CAMK2D can attenuate the retinal degeneration induced by NaIO3, which was achieved by regulating the CFI.

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.

Palmitoyl-L-carnitine induces tau phosphorylation and mitochondrial dysfunction in neuronal cells

Alzheimer's disease (AD) is characterized by cognitive decline and memory loss, involving mechanisms such as tau hyperphosphorylation and mitochondrial dysfunction. Increasing evidence suggests that age-related alterations in metabolite levels are crucial for the pathogenesis of AD. Here, we analyzed serum metabolites from mice of various ages (2, 4, 14, and 21 months old) using mass spectrometry. We identified palmitoyl-L-carnitine as a key metabolite with significantly increased levels in aged mice. In vitro experiments with SH-SY5Y neuronal cells demonstrated that palmitoyl-L-carnitine treatment enhanced tau phosphorylation, increased mitochondrial fission, and elevated intracellular calcium levels. Furthermore, the increased levels of tau phosphorylation were significantly reduced by the inhibition of GSK-3β, CDK5, and calpain, indicating that tau kinases activated by calcium overload are directly involved in the increase of tau phosphorylation. Considering that mitochondrial fission is related to mitochondrial dysfunction, we propose that the elevated level of serum palmitoyl-L-carnitine during aging contributes to AD pathology through these pathways. These findings highlight the significant role of lipid metabolism in neurodegeneration and offer potential therapeutic targets for age-related diseases, including AD.

Impact of smokeless tobacco on psychological and oxidative stress in unemployed indian youth

In India, tobacco (nicotine) addiction among youth has increased, leading to substantial socioeconomic burdens, mortality, and morbidity. While minimal short-term nicotine consumption may have antioxidant effects, chronic exposure results in various adverse health outcomes. This study examines the impact of chronic nicotine consumption on cellular oxidative stress and psychological stress, and their correlation with Homocysteine (Hcy) levels in unemployed tobacco consumers. This case-control study included 156 healthy, educated, unemployed male volunteers aged 20-40 years, divided into nicotine-addicted (n = 80) and non-addicted (n = 76) groups. Psychological stress was assessed using perceived stress scales (PSS) and coping self-efficacy (CSE) scales. Oxidative stress markers, including Malondialdehyde (MDA), Superoxide Dismutase (SOD), and Catalase, were measured. Hcy levels were quantified using high-performance liquid chromatography (HPLC). Nicotine-addicted participants exhibited significantly higher perceived stress (p = 0.0001) and lower coping self-efficacy (p = 0.0001) compared to non-addicted individuals. MDA levels in erythrocytes were significantly increased (p = 0.0006), while SOD (p = 0.0001) and Catalase (p = 0.02) activities were significantly decreased in the addicted group. Nicotine intake influenced Hcy concentrations, with 55% of addicted individuals falling into moderate, 27.5% into intermediate, and 7.5% into severe Hcy categories. Chronic nicotine intake also reflected the hematological parameters (WBCs, RBCs, HGB, and Platelets). Chronic tobacco consumption induces oxidative stress and perceived psychological stress, leading to elevated Hcy levels in nicotine consumers. The study highlights the detrimental effects of nicotine addiction on cellular defensive mechanisms, emphasizing the need for targeted interventions to address this growing health issue among unemployed Indian youth.

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.

Efficacy of Digital Dance on Brain Imagery, Cognition, and Health: Randomized Controlled Trial

BACKGROUND

Multidomain interventions have demonstrable benefits for promoting healthy aging, but self-empowerment strategies to sustain long-term gains remain elusive.

OBJECTIVE

This study evaluated the effects of digital somatosensory dance game participation on brain imagery changes as primary outcomes and other physical and mental health measures as secondary outcomes related to healthy aging.

METHODS

Between August 31, 2020, and June 27, 2021, this randomized controlled trial recruited 60 eligible participants older than 55 years with no recent engagement in digital dance games. A computer-generated randomization sequence was used to allocate participants 1:1, without stratification, to an intervention group (n=30) who underwent digital somatosensory dance game training or a control group (n=30). An anonymized code masked the intervention allocations from the investigators, and individuals who assigned the interventions were not involved in analyzing the study data. The intervention entailed two 30-minute dance game sessions per week for 6 months, and the control group received healthy aging education. Primary outcomes were brain imagery changes. All variables were measured at baseline and the 6-month follow-up, and intervention effects were estimated using t tests with intention-to-treat analyses.

RESULTS

Compared with the control group, intervention participants had significantly different brain imagery in the gray matter volume (GMV) of the left putamen (estimate 0.016, 95% CI 0.008 to 0.024; P<.001), GMV of the left pallidum (estimate 0.02, 95% CI 0.006 to 0.034; P=.004), and fractional amplitude of low frequency fluctuations of the left pallidum (estimate 0.262, 95% CI 0.084 to 0.439; P=.004). Additionally, the intervention group had different imagery in the cerebellum VI GMV (estimate 0.011, 95% CI 0.003 to 0.02; P=.01). The intervention group also had improved total Montreal Cognitive Assessment scores (estimate 1.2, 95% CI 0.27 to -2.13; P<.01), quality of life (estimate 7.08, 95% CI 2.35 to 11.82; P=.004), and time spent sitting on weekdays (estimate -1.96, 95% CI -3.33 to -0.60; P=.005). Furthermore, dance performance was significantly associated with cognitive performance (P=.003), health status (P=.14), resilience (P=.007), and demoralization (P<.001).

CONCLUSIONS

Digital somatosensory dance game participation for 6 months was associated with brain imagery changes in multiple regions involving somatosensory, motor, visual, and attention functions, which were consistent with phenotypic improvements associated with healthy aging.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05411042; https://clinicaltrials.gov/study/NCT05411042.

Novel homozygous ADK out-of-frame deletion causes adenosine kinase deficiency with rare phenotypes of sepsis, metabolites disruption and neutrophil dysfunction

Adenosine kinase deficiency (OMIM #614300) is a type of inborn errors of metabolism with multiorgan symptoms primarily neurological disorders, hepatic impairment, global developmental delay, and mild dysmorphism. The genetic causes of adenosine kinase deficiency are homozygous or compound heterozygous loss-of-function variants of ADK. To date, fewer than 25 cases of adenosine kinase deficiency have been reported worldwide and none have been reported in China. In this research, trio whole-exome sequencing (Trio-WES) identified a novel homozygous ADK (NM_001123.4) out-of-frame deletion, c.518_519delCA (p.Thr173Serfs*15), in a Chinese patient with rare phenotypes of sepsis, metabolites disruption and neutrophil dysfunction. This variant was dysfunctional, with marked reduction of ADK level in both the patient's peripheral blood and cells transfected with the corresponding variant. Additionally, metabolomics detected by high-throughput mass spectrometry showed disturbances in the methionine (Met) and energy pathway. RNA sequencing (RNA-seq) of the patient's peripheral blood suggested a defective anti-inflammatory response characterized by impaired neutrophil activation, migration, and degranulation, which might be the primary cause for the sepsis. To our knowledge, we identified the first Chinese patient of adenosine kinase deficiency with a novel homozygous out-of-frame deletion in ADK causing multiorgan disorders, metabolites disruption, rare phenotypes of sepsis, and neutrophil dysfunction. Our findings broaden the genetic spectrum and pathogenic mechanisms of adenosine kinase deficiency.

Repurposing effect of cardiovascular-metabolic drug to increase lifespan: a systematic review of animal studies and current clinical trial progress

With the increase in life expectancy, aging has emerged as a significant health concern. Due to its various mechanisms of action, cardiometabolic drugs are often repurposed for other indications, including aging. This systematic review analyzed and highlighted the repositioning potential of cardiometabolic drugs to increase lifespan as an aging parameter in animal studies and supplemented by information from current clinical trial registries. Systematic searching in animal studies was performed based on PICO: "animal," "cardiometabolic drug," and "lifespan." All clinical trial registries were also searched from the WHO International Clinical Trial Registry Platform (ICTRP). Analysis of 49 animal trials and 10 clinical trial registries show that various cardiovascular and metabolic drugs have the potential to target lifespan. Metformin, acarbose, and aspirin are the three most studied drugs in animal trials. Aspirin and acarbose are the promising ones, whereas metformin exhibits various results. In clinical trial registries, metformin, omega-3 fatty acid, acarbose, and atorvastatin are currently cardiometabolic drugs that are repurposed to target aging. Published clinical trial results show great potential for omega-3 and metformin in healthspan. Systematic Review Registration: crd.york.ac.uk/prospero/display_record.php?RecordID=457358, identifier: CRD42023457358.

N-homocysteinylation of DJ-1 promotes neurodegeneration in Parkinson's disease

DJ-1, also known as Parkinson's disease protein 7 (Park7), is a multifunctional protein that regulates oxidative stress and mitochondrial function. Dysfunction of DJ-1 is implicated in the pathogenesis of Parkinson's disease (PD). Hyperhomocysteinemia is associated with an increased risk of PD. Here we show that homocysteine thiolactone (HTL), a reactive thioester of homocysteine (Hcy), covalently modifies DJ-1 on the lysine 182 (K182) residue in an age-dependent manner. The N-homocysteinylation (N-hcy) of DJ-1 abolishes its neuroprotective effect against oxidative stress and mitochondrial dysfunction, exacerbating cell toxicity. Blocking the N-hcy of DJ-1 restores its protective effect. These results indicate that the N-hcy of DJ-1 abolishes its neuroprotective effect and promotes the progression of PD. Inhibiting the N-hcy of DJ-1 may exert neuroprotective effect against PD.

Association of Increased Homocysteine Levels with Impaired Folate Metabolism and Vitamin B Deficiency in Early-Onset Multiple Sclerosis

The contents of homocysteine (HCy), cyanocobalamin (vitamin B12), folic acid (vitamin B9), and pyridoxine (vitamin B6) were analyzed and the genotypes of the main gene polymorphisms associated with folate metabolism (C677T and A1298C of the MTHFR gene, A2756G of the MTR gene and A66G of the MTRR gene) were determined in children at the onset of multiple sclerosis (MS) (with disease duration of no more than six months), healthy children under 18 years (control group), healthy adults without neurological pathology, adult patients with MS at the onset of disease, and adult patients with long-term MS. A significant increase in the HCy levels was found in children at the MS onset compared to healthy children of the corresponding age. It was established that the content of HCy in children has a high predictive value. At the same time, an increase in the HCy levels was not accompanied by the deficiency of vitamins B6, B9, and B12 in the blood. The lack of correlation between the laboratory signs of vitamin deficiency and HCy levels may be due to the polymorphic variants of folate cycle genes. An increased HCy level should be considered as a marker of functional disorders of folate metabolism accompanying the development of pathological process in pediatric MS. Our finding can be used to develop new approaches to the prevention of demyelination in children and treatment of pediatric MS.

Effects of Aerobic Treadmill Training on Oxidative Stress Parameters, Metabolic Enzymes, and Histomorphometric Changes in Colon of Rats with Experimentally Induced Hyperhomocysteinemia

The aim of this study was to investigate the effects of aerobic treadmill training regimen of four weeks duration on oxidative stress parameters, metabolic enzymes, and histomorphometric changes in the colon of hyperhomocysteinemic rats. Male Wistar albino rats were divided into four groups (n = 10, per group): C, 0.9% NaCl 0.2 mL/day subcutaneous injection (s.c.) 2x/day; H, homocysteine 0.45 µmol/g b.w./day s.c. 2x/day; CPA, saline (0.9% NaCl 0.2 mL/day s.c. 2x/day) and an aerobic treadmill training program; and HPA, homocysteine (0.45 µmol/g b.w./day s.c. 2x/day) and an aerobic treadmill training program. The HPA group had an increased level of malondialdehyde (5.568 ± 0.872 μmol/mg protein, p = 0.0128 vs. CPA (3.080 ± 0.887 μmol/mg protein)), catalase activity (3.195 ± 0.533 U/mg protein, p < 0.0001 vs. C (1.467 ± 0.501 U/mg protein), p = 0.0012 vs. H (1.955 ± 0.293 U/mg protein), and p = 0.0003 vs. CPA (1.789 ± 0.256 U/mg protein)), and total superoxide dismutase activity (9.857 ± 1.566 U/mg protein, p < 0.0001 vs. C (6.738 ± 0.339 U/mg protein), p < 0.0001 vs. H (6.015 ± 0.424 U/mg protein), and p < 0.0001 vs. CPA (5.172 ± 0.284 U/mg protein)) were detected in the rat colon. In the HPA group, higher activities of lactate dehydrogenase (2.675 ± 1.364 mU/mg protein) were detected in comparison to the CPA group (1.198 ± 0.217 mU/mg protein, p = 0.0234) and higher activities of malate dehydrogenase (9.962 (5.752-10.220) mU/mg protein) were detected in comparison to the CPA group (4.727 (4.562-5.299) mU/mg protein, p = 0.0385). Subchronic treadmill training in the rats with hyperhomocysteinemia triggers the colon tissue antioxidant response (by increasing the activities of superoxide dismutase and catalase) and elicits an increase in metabolic enzyme activities (lactate dehydrogenase and malate dehydrogenase). This study offers a comprehensive assessment of the effects of aerobic exercise on colonic tissues in a rat model of hyperhomocysteinemia, evaluating a range of biological indicators including antioxidant enzyme activity, metabolic enzyme activity, and morphometric parameters, which suggested that exercise may confer protective effects at both the physiological and morphological levels.

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.

Homocysteine and Lp-PLA2 levels: Diagnostic value in coronary heart disease

Coronary heart disease (CHD) is the leading cause of mortality worldwide. Identifying effective diagnostic markers and understanding risk factors is crucial for prevention and management. This study aimed to investigate the levels of homocysteine (Hcy) and lipoprotein-associated phospholipase A2 (Lp-PLA2) in human plasma and their roles in the diagnosis and prognosis of CHD. A retrospective study was conducted on 232 patients with CHD, divided into Acute Myocardial Infarction, unstable angina pectoris, and stable angina pectoris groups, and a control group of 75 healthy adults. Blood samples were analyzed for serum Hcy and Lp-PLA2 levels using the cycling enzyme method and ELISA method, respectively. Statistical analyses were performed to evaluate the risk factors, and diagnostic efficacy was assessed using receiver operating characteristic (ROC) curves. No significant differences in age and sex were observed between the study and control groups, whereas marked disparities in risk factors such as obesity, hypertension, diabetes, and hyperlipidemia were noted. Significant differences in serum Hcy and Lp-PLA2 levels were identified among the CHD subgroups. Univariate and multivariate logistic regression analyses revealed that Hcy, Lp-PLA2, hypertension, and hyperlipidemia were significant risk factors for CHD. The combined diagnostic Area Under the Curve (AUC) for Hcy and Lp-PLA2 was found to be higher than that when using them individually. This study identified the elevation of Hcy and Lp-PLA2 levels as independent risk factors for CHD, and their conjoint analysis significantly enhanced clinical diagnostic efficacy. These findings provide valuable insights for CHD diagnosis, treatment, and prevention, highlighting the importance of these markers in CHD management.

The Role of Methionine-Rich Diet in Unhealthy Cerebrovascular and Brain Aging: Mechanisms and Implications for Cognitive Impairment

As aging societies in the western world face a growing prevalence of vascular cognitive impairment and Alzheimer's disease (AD), understanding their underlying causes and associated risk factors becomes increasingly critical. A salient concern in the western dietary context is the high consumption of methionine-rich foods such as red meat. The present review delves into the impact of this methionine-heavy diet and the resultant hyperhomocysteinemia on accelerated cerebrovascular and brain aging, emphasizing their potential roles in cognitive impairment. Through a comprehensive exploration of existing evidence, a link between high methionine intake and hyperhomocysteinemia and oxidative stress, mitochondrial dysfunction, inflammation, and accelerated epigenetic aging is drawn. Moreover, the microvascular determinants of cognitive deterioration, including endothelial dysfunction, reduced cerebral blood flow, microvascular rarefaction, impaired neurovascular coupling, and blood-brain barrier (BBB) disruption, are explored. The mechanisms by which excessive methionine consumption and hyperhomocysteinemia might drive cerebromicrovascular and brain aging processes are elucidated. By presenting an intricate understanding of the relationships among methionine-rich diets, hyperhomocysteinemia, cerebrovascular and brain aging, and cognitive impairment, avenues for future research and potential therapeutic interventions are suggested.

Appraising the Role of Astrocytes as Suppliers of Neuronal Glutathione Precursors

The metabolism and intercellular transfer of glutathione or its precursors may play an important role in cellular defense against oxidative stress, a common hallmark of neurodegeneration. In the 1990s, several studies in the Neurobiology field led to the widely accepted notion that astrocytes produce large amounts of glutathione that serve to feed neurons with precursors for glutathione synthesis. This assumption has important implications for health and disease since a reduction in this supply from astrocytes could compromise the capacity of neurons to cope with oxidative stress. However, at first glance, this shuttling would imply a large energy expenditure to get to the same point in a nearby cell. Thus, are there additional underlying reasons for this expensive mechanism? Are neurons unable to import and/or synthesize the three non-essential amino acids that are the glutathione building blocks? The rather oxidizing extracellular environment favors the presence of cysteine (Cys) as cystine (Cis), less favorable for neuronal import. Therefore, it has also been proposed that astrocytic GSH efflux could induce a change in the redox status of the extracellular space nearby the neurons, locally lowering the Cis/Cys ratio. This astrocytic glutathione release would also increase their demand for precursors, stimulating Cis uptake, which these cells can import, further impacting the local decline of the Cis/Cys ratio, in turn, contributing to a more reduced extracellular environment and subsequently favoring neuronal Cys import. Here, we revisit the experimental evidence that led to the accepted hypothesis of astrocytes acting as suppliers of neuronal glutathione precursors, considering recent data from the Human Protein Atlas. In addition, we highlight some potential drawbacks of this hypothesis, mainly supported by heterogeneous cellular models. Finally, we outline additional and more cost-efficient possibilities by which astrocytes could support neuronal glutathione levels, including its shuttling in extracellular vesicles.

Association of vitamins with hearing loss, vision disorder and sleep problem in the US general population

Based on nationally representative samples from US, we aimed to assess the associations of vitamins with hearing loss, vision disorder and sleep problem. A total of 25,312, 8425 and 24,234 participants were included in this study to investigate the relationship of vitamins with hearing loss, vision disorder and sleep problem from National Health and Nutrition Examination Survey, respectively. Vitamins including niacin, folic acid, vitamin B6, A, C, E and carotenoids were considered in our study. Logistic regression models were used to assess the associations between all included dietary vitamin intake concentrations and the prevalence of specific outcomes. Increased lycopene (odds ratio [OR]: 0.904, 95% confidence interval [CI]: 0.829-0.985) intake was associated with a deceased prevalence of hearing loss. Higher dietary intake of folic acid (OR: 0.637, 95% CI: 0.443-0.904), vitamin B6 (0.667, 0.465-0.947), alpha-carotene (0.695, 0.494-0.968), beta-carotene (0.703, 0.505-0.969) and lutein + zeaxanthin (0.640, 0.455-0.892) were associated with a decreased prevalence of vision disorder. The inversely associations of sleeping problem with niacin (OR: 0.902, 95% CI: 0.826-0.985), folic acid (0.882, 0.811-0.959), vitamin B6 (0.892, 0.818-0.973), vitamin C (0.908, 0.835-0.987), vitamin E (0.885, 0.813-0.963) and lycopene (0.919, 0.845-0.998) were also observed. Our findings provide evidence that increased specific vitamin intake is associated with decreased prevalence of hearing loss, vision disorder and sleep problem.

High Homocysteine Levels Are Associated with Cognitive Impairment in Patients Who Recovered from COVID-19 in the Long Term

In this study, we measured the levels of depression and cognition in people recovering from COVID-19. Moreover, we aimed to investigate the relationship between depression and cognition levels by measuring homocysteine concentrations. It included 62 people recovering from COVID-19 (at least 3 months after positive RT-PCR) and 64 people without COVID-19 (control group). At first, the homocysteine levels of participants were measured. Beck Depression Inventory (BDI) and Montreal Cognitive Assessment (MoCA) were performed to collect data. Homocysteine levels of the group recovering from COVID-19 (x- = 19.065 µmol/L) were higher than the control group (x- = 11.313 µmol/L). There was no significant difference between the groups for BDI scores. The MoCA scores of the group recovering from COVID-19 (x- = 20.774) were lower than the control group (x- = 24.297). There was a negative high (r = -0.705, p < 0.001) correlation between homocysteine levels and MoCA scores. Linear regression analysis is shown to be significant, and the MoCA explanatory value of the variables in the model is 58.6% (p < 0.0001). A 1 µmol/L observed increase in homocysteine level constituted a risk for a 0.765-point decrease in MOCA scores. In patients recovering from COVID-19, early interventions to high homocysteine levels may prevent cognitive impairments that may persist in the long term.

Diet's Role in Modifying Risk of Alzheimer's Disease: History and Present Understanding

Diet is an important nonpharmacological risk-modifying factor for Alzheimer's disease (AD). The approaches used here to assess diet's role in the risk of AD include multi-country ecological studies, prospective and cross-sectional observational studies, and laboratory studies. Ecological studies have identified fat, meat, and obesity from high-energy diets as important risk factors for AD and reported that AD rates peak about 15-20 years after national dietary changes. Observational studies have compared the Western dietary pattern with those of the Dietary Approaches to Stop Hypertension (DASH), Mediterranean (MedDi), and Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND) diets. Those studies identified AD risk factors including higher consumption of saturated and total fats, meat, and ultraprocessed foods and a lower risk of AD with higher consumption of fruits, legumes, nuts, omega-3 fatty acids, vegetables, and whole grains. Diet-induced factors associated with a significant risk of AD include inflammation, insulin resistance, oxidative stress, elevated homocysteine, dietary advanced glycation end products, and trimethylamine N-oxide. The molecular mechanisms by which dietary bioactive components and specific foods affect risk of AD are discussed. Given most countries' entrenched food supply systems, the upward trends of AD rates would be hard to reverse. However, for people willing and able, a low-animal product diet with plenty of anti-inflammatory, low-glycemic load foods may be helpful.

Isolation of Primary Mouse Retinal Pigmented Epithelium Cells

The retinal pigmented epithelium (RPE) layer lies immediately behind the photoreceptors and harbors a complex metabolic system that plays several critical roles in maintaining the photoreceptors' function. Thus, the RPE structure and function are essential to sustain normal vision. This manuscript presents an established protocol for primary mouse RPE cell isolation. RPE isolation is a great tool to investigate the molecular mechanisms underlying RPE pathology in the different mouse models of ocular disorders. Furthermore, RPE isolation can help in comparing primary mouse RPE cells isolated from wild-type and genetically modified mice, as well as testing drugs that can accelerate the development of therapy for visual disorders. The manuscript presents a step-by-step RPE isolation protocol; the entire procedure, from enucleation to seeding, takes approximately 4 hours. The media shouldn't be changed for 5-7 days after seeding, to allow the growth of the isolated cells without disturbance. This process is followed by the characterization of morphology, pigmentation, and specific markers in the cells via immunofluorescence. Cells can be passaged a maximum of three or four times.

Hyperhomocysteinemia and intracranial aneurysm: A mendelian randomization study

Objective

To investigate the link between genetic variants associated with plasma homocysteine levels and risk of intracranial aneurysm (IA) using two-sample Mendelian randomization.

Methods

We used single-nucleotide polymorphisms associated with human plasma homocysteine levels as instrumental variables for the primary analysis in a genome-wide association study of 44,147 subjects of European ancestry. Summary-level statistics were obtained for 79,429 individuals, including 7,495 IA cases and 71,934 controls. To enhance validity, five different Mendelian randomization methods (MR-Egger, weighted median, inverse variance weighted, simple mode, and weighted mode) were used for the analyses.

Results

The inverse variance weighted analysis method produced P-values of 0.398 for aneurysmal subarachnoid hemorrhage [odds ratio (OR): 1.104; 95% confidence interval (CI): 0.878–1.387], 0.246 for IA (OR: 1.124; 95% CI: 0.923–1.368), and 0.644 for unruptured IA (OR: 1.126; 95% CI: 0.682–1.858). The MR-Egger analysis showed no association between IAs and homocysteine, with all P > 0.05.

Conclusion

Using gene-related instrumental variables, the Mendelian randomization analyses demonstrated a lack of an association between plasma homocysteine levels and IAs or aneurysmal subarachnoid hemorrhage.

Special Issue Editorial: "Infections, Inflammation and Neurodegeneration in Alzheimer Disease" Infections, Neuronal Senescence, and Dementia

Alzheimer's disease (AD) is a complex chronic disease of the brain characterized by several neurodegenerative mechanisms and is responsible for most dementia cases in the elderly. Declining immunity during ageing is often associated with peripheral chronic inflammation, and chronic neuroinflammation is a constant component of AD brain pathology. In the Special Issue published in 2021 eight papers were collected regarding different aspects of neurodegeneration associated with AD. Five papers presented and discussed infectious agents involved in brain AD pathology and three discussed data regarding receptors regulation and possible treatment of the disease. Below I will discuss and further elaborate on topics related to infections, inflammation, and neurodegenerative pathways in AD and brain senescence. The topic presented here may contribute to early intervention protocols for preventing or slowing the progression of cognitive deterioration in the elderly.

Epigallocatechin-3-gallate Enhances Cognitive and Memory Performance and Protects Against Brain Injury in Methionine-induced Hyperhomocysteinemia Through Interdependent Molecular Pathways

Brain injury and cognitive impairment are major health issues associated with neurodegenerative diseases in young and aged persons worldwide. Epigallocatechin-3-gallate (EGCG) was studied for its ability to protect against methionine (Met)-induced brain damage and cognitive dysfunction. Male mice were given Met-supplemented in drinking water to produce hyperhomocysteinemia (HHcy)-induced animals. EGCG was administered daily concurrently with Met by gavage. EGCG attenuated the rise in homocysteine levels in the plasma and the formation of amyloid-β and tau protein in the brain. Cognitive and memory impairment in HHcy-induced mice were significantly improved by EGCG administration. These results were associated with improvement in glutamate and gamma-aminobutyric acid levels in the brain. EGCG maintained the levels of glutathione and the activity of antioxidant enzymes in the brain. As a result of the reduction of oxidative stress, EGCG protected against DNA damage in Met-treated mice. Moreover, maintaining the redox balance significantly ameliorated neuroinflammation evidenced by the normalization of IL-1β, IL-6, tumor necrosis factor α, C-reactive protein, and IL-13 in the same animals. The decreases in both oxidative stress and inflammatory cytokines were significantly associated with upregulation of the antiapoptotic Bcl-2 protein and downregulation of the proapoptotic protein Bax, caspases 3 and 9, and p53 compared with Met-treated animals, indicating a diminution of neuronal apoptosis. These effects reflect and explain the improvement in histopathological alterations in the hippocampus of Met-treated mice. In conclusion, the beneficial effects of EGCG may be due to interconnecting pathways, including modulation of redox balance, amelioration of inflammation, and regulation of antiapoptotic proteins.

Association of Homocysteine and Risks of Long-Term Cardiovascular Events and All-Cause Death among Older Patients with Obstructive Sleep Apnea: A Prospective Study

OBJECTIVES

This study aimed to assess whether raised baseline plasma tHcy concentrations increased the risks of major adverse cardiovascular events (MACE) and all-cause death outcomes in older patients with obstructive sleep apnea (OSA).

DESIGN

A multicenter, prospective, observational study.

SETTING

Beijing, Shandong Province, Gansu Province of China.

PARTICIPANTS

A total of 1, 290 OSA patients aged 60 to 96 years from sleep centers of six hospitals in China consecutively recruited between January 2015 and October 2017.

MEASUREMENTS

Cox proportional models assessed the association between tHcy and the risk of new-onset all events among Chinese older OSA patients.

RESULTS

The final analysis (60.1% male; median age, 66 years) used data from 1, 100 subjects during a median follow-up of 42 months, a total of 105 (9.5%) patients developed MACE and 42 (3.8%) patients died. Multivariable Cox regression analysis showed higher adjusted hazard ratios (aHRs) of MACE, myocardial infarction (MI), hospitalization for unstable angina, and composite of all events with tHcy levels in the 4th quartile (HR=5.93, 95% CI: 2.79-12.59; HR=4.72, 95% CI:1.36-4.61; HR=4.26, 95% CI:1.62-5.71; HR=4.17, 95% CI:2.23-7.81) and the 3rd quartile (HR=3.79, 95% CI:1.76-8.20; HR=3.65, 95% CI:1.04-2.98; HR=2.75, 95% CI:1.08-3.76; HR=2.51, 95% CI:1.31-4.83) compared to reference tHcy levels in quartile 1, respectively, while the aHRs (95% CIs) of all-cause death showed significantly higher only in the highest tHcy level quartile than in the lowest quartile (HR=3.20, 95% CI=1.16-8.84, P=0.025) with no significant differences in risks of cardiovascular death and hospitalisation for heart failure among groups (P>0.05).

CONCLUSIONS

tHcy, a marker of prognosis for older OSA patients, was significantly associated with the increased risk of MACE and all-cause death in this population independent of BMI, smoking status, and other potential risk factors, but not all clinical components events of MACE. New therapeutic approaches for older patients with OSA should mitigate tHcy-associated risks of MACE, and even all-cause death.