The role of iron in brain ageing and neurodegenerative disorders

Iron depletion has different consequences on the growth and survival of Toxoplasma gondii strains

Toxoplasma gondii is an obligate intracellular parasite responsible for a pathology called toxoplasmosis, which primarily affects immunocompromised individuals and developing foetuses. The parasite can scavenge essential nutrients from its host to support its growth and survival. Among them, iron is one of the most important elements needed to sustain basic cellular functions as it is involved in a number of key metabolic processes, including oxygen transport, redox balance, and electron transport. We evaluated the effects of an iron chelator on the development of several parasite strains and found that they differed in their ability to tolerate iron depletion. The growth of parasites usually associated with a model of acute toxoplasmosis was strongly affected by iron depletion, whereas cystogenic strains were less sensitive as they were able to convert into persisting developmental forms that are associated with the chronic form of the disease. Ultrastructural and biochemical characterization of the impact of iron depletion on parasites also highlighted striking changes in both their metabolism and that of the host, with a marked accumulation of lipid droplets and perturbation of lipid homoeostasis. Overall, our study demonstrates that although acute iron depletion has an important effect on the growth of T. gondii, it has a more profound impact on actively dividing parasites, whereas less metabolically active parasite forms may be able to avoid some of the most detrimental consequences.

Ferroptosis mechanism and Alzheimer's disease

Regulated cell death is a genetically determined form of programmed cell death that commonly occurs during the development of living organisms. This process plays a crucial role in modulating homeostasis and is evolutionarily conserved across a diverse range of living organisms. Ferroptosis is a classic regulatory mode of cell death. Extensive studies of regulatory cell death in Alzheimer's disease have yielded increasing evidence that ferroptosis is closely related to the occurrence, development, and prognosis of Alzheimer's disease. This review summarizes the molecular mechanisms of ferroptosis and recent research advances in the role of ferroptosis in Alzheimer's disease. Our findings are expected to serve as a theoretical and experimental foundation for clinical research and targeted therapy for Alzheimer's disease.

Physical Exercise-Induced Activation of NRF2 and BDNF as a Promising Strategy for Ferroptosis Regulation in Parkinson's Disease

Parkinson's disease (PD) is a progressive neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra. Ferroptosis, an iron-dependent form of regulated cell death, may contribute to the progression of PD owing to an unbalanced brain redox status. Physical exercise is a complementary therapy that can modulate ferroptosis in PD by regulating the redox system through the activation of nuclear factor (erythroid-derived 2)-like 2 (NRF2) and brain-derived neurotrophic factor (BDNF) signaling. However, the precise effects of physical exercise on ferroptosis in PD remain unclear. In this review, we explored how physical exercise influences NRF2 and BDNF signaling and affects ferroptosis in PD. We further investigated relevant publications over the past two decades by searching the PubMed, Web of Science, and Google Scholar databases using keywords related to physical exercise, PD, ferroptosis, and neurotrophic factor antioxidant signaling. This review provides insights into current research gaps and demonstrates the necessity for future research to elucidate the specific mechanisms by which exercise regulates ferroptosis in PD, including the assessment of different exercise protocols and their long-term effects. Ultimately, exploring these aspects may lead to the development of improved exercise interventions for the better management of patients with PD.

Chronic dietary iron overload affects hepatic iron metabolism and cognitive behavior in Wistar rats

BACKGROUND

Iron accumulation in organs affects iron metabolism, leading to deleterious effects on the body. Previously, it was studied that high dietary iron in various forms and concentrations influences iron metabolism, resulting in iron accumulation in the liver and spleen and cognitive impairment. However, the actual mechanism and impact of long-term exposure to high dietary iron remain unknown. As a result, we postulated that iron overload caused by chronic exposure to excessive dietary iron supplementation would play a role in iron dyshomeostasis and inflammation in the liver and brain of Wistar rats.

METHODS

Animals were segregated into control, low iron (FAC-Ferric Ammonium Citrate 5000 ppm), and high iron dose group (FAC 20,000 ppm). The outcome of dietary iron overload on Wistar rats was evaluated in terms of body weight, biochemical markers, histological examination of liver and brain tissue, and cognitive-behavioral studies. Also, gene expression of rat brain tissue involving iron transporters Dmt1, TfR1, iron storage protein Fpn1, inflammatory markers Nf-kB, Tnf-α, Il-6, and hepcidin was performed.

RESULTS

Our data indicate that excess iron supplementation for 30 weeks leads to decreased body weight, increased serum iron levels, and decreased RBC levels in iron fed Wistar rats. Morris water maze (MWM) studies after 30 weeks showed increased escape latency in the high iron dose group compared with the control group. Histological studies of the high iron dose group showed an iron accumulation in the liver and brain loss of cellular architecture, and cellular degeneration was observed. Excess iron treatment showed upregulation of the Dmt1 gene in iron metabolism and a remarkable increase in the Nf-kB gene in rat brain tissue.

CONCLUSION

The results show chronic excess iron supplementation leads to iron accumulation in the liver, leading to inflammation in Wistar rats.

Cerebrospinal Fluid-In Gradient of Cortical and Deep Gray Matter Damage in Multiple Sclerosis

BACKGROUND AND OBJECTIVES

A CSF-in gradient in cortical and thalamic gray matter (GM) damage has been found in multiple sclerosis (MS). We concomitantly explored the patterns of cortical, thalamic, and caudate microstructural abnormalities at progressive distances from CSF using a multiparametric MRI approach.

METHODS

For this cross-sectional study, from 3T 3D T1-weighted scans, we sampled cortical layers at 25%-50%-75% depths from pial surface and thalamic and caudate bands at 2-3-4 voxels from the ventricular-GM interface. Using linear mixed models, we tested between-group comparisons of magnetization transfer ratio (MTR) and R2* layer-specific z-scores, CSF-in across-layer z-score changes, and their correlations with clinical (disease duration and disability) and structural (focal lesions, brain, and choroid plexus volume) MRI measures.

RESULTS

We enrolled 52 patients with MS (33 relapsing-remitting [RRMS], 19 progressive [PMS], mean age: 46.4 years, median disease duration: 15.1 years, median: EDSS 2.0) and 70 controls (mean age 41.5 ± 12.8). Compared with controls, RRMS showed lower MTR values in the outer and middle cortical layers (false-discovery rate [FDR]-p ≤ 0.025) and lower R2* values in all 3 cortical layers (FDR-p ≤ 0.016). PMS had lower MTR values in the outer and middle cortical (FDR-p ≤ 0.016) and thalamic (FDR-p ≤ 0.048) layers, and in the outer caudate layer (FDR-p = 0.024). They showed lower R2* values in the outer cortical layer (FDR-p = 0.003) and in the outer thalamic layer (FDR-p = 0.046) and higher R2* values in all 3 caudate layers (FDR-p ≤ 0.031). Both RRMS and PMS had a gradient of damage, with lower values closer to the CSF, for cortical (FDR-p ≤ 0.002) and thalamic (FDR-p ≤ 0.042) MTR. PMS showed a gradient of damage for cortical R2* (FDR-p = 0.005), thalamic R2* (FDR-p = 0.004), and caudate MTR (FDR-p ≤ 0.013). Lower MTR and R2* of outer cortical, thalamic, and caudate layers and steeper gradient of damage toward the CSF were significantly associated with older age, higher T2-hyperintense white matter lesion volume, higher thalamic lesion volume, and lower brain volume (β ≥ 0.08, all FDR-p ≤ 0.040). Lower MTR of outer caudate layer was associated with more severe disability (β = -0.26, FDR-p = 0.040). No correlations with choroid plexus volume were found.

DISCUSSION

CSF-in damage gradients are heterogeneous among different GM regions and through MS course, possibly reflecting different dynamics of demyelination and iron loss/accumulation.

Rethinking neurodegenerative diseases: neurometabolic concept linking lipid oxidation to diseases in the central nervous system

ABSTRACT

Currently, there is a lack of effective medicines capable of halting or reversing the progression of neurodegenerative disorders, including amyotrophic lateral sclerosis, Parkinson's disease, multiple sclerosis, or Alzheimer's disease. Given the unmet medical need, it is necessary to reevaluate the existing paradigms of how to target these diseases. When considering neurodegenerative diseases from a systemic neurometabolic perspective, it becomes possible to explain the shared pathological features. This innovative approach presented in this paper draws upon extensive research conducted by the authors and researchers worldwide. In this review, we highlight the importance of metabolic mitochondrial dysfunction in the context of neurodegenerative diseases. We provide an overview of the risk factors associated with developing neurodegenerative disorders, including genetic, epigenetic, and environmental factors. Additionally, we examine pathological mechanisms implicated in these diseases such as oxidative stress, accumulation of misfolded proteins, inflammation, demyelination, death of neurons, insulin resistance, dysbiosis, and neurotransmitter disturbances. Finally, we outline a proposal for the restoration of mitochondrial metabolism, a crucial aspect that may hold the key to facilitating curative therapeutic interventions for neurodegenerative disorders in forthcoming advancements.

Relationship Between a High-Fat Diet, Reduced Mobility, and Trace Element Overload in the Olfactory Bulbs of C57BL/6J and DBA/2J Mice

The dysregulation of trace elements in the brain, which can be caused by genetic or environmental factors, has been associated with disease and compromised mobility. Research regarding trace elements and motor function has focused mainly on the basal ganglia, but few studies have examined the olfactory bulb in this context. Diets high in fat have been shown to have consequences of dysregulated iron and manganese in the brain and disrupted motor activity. The aim of our study was to examine the relationship between mobility and trace element disruption in the olfactory bulb in male and female C57BL/6J and DBA/2J mice fed a high-fat diet. Mobility was significantly reduced in male C57BL/6Js, but the correlation between iron and manganese in the olfactory bulb with velocity, distance travelled, and habituation was not statistically significant. However, there appears to be an overall pattern of a high-fat diet having a statistically significant impact individually on elevated iron and manganese in the olfactory bulb, reduced velocity, reduced distance travelled, and reduced habituation mainly in the male C57BL/6J strain. We found similar trends within the scientific literature to suggest that dysregulated trace element status in the olfactory bulb may be related to motor function in both humans and animals and that males may be more susceptible to the negative outcomes. Our findings contribute new information regarding the impact of diet on the brain, behavior, and potential connection between trace element dysregulation in the olfactory bulb with mobility.

MRI-derived brain iron, grey matter volume, and risk of dementia and Parkinson's disease: Observational and genetic analysis in the UK Biobank cohort

BACKGROUND

Iron overload is observed in neurodegenerative diseases, especially Alzheimer's disease (AD) and Parkinson's disease (PD). Homozygotes for the iron-overload (haemochromatosis) causing HFE p.C282Y variant have increased risk of dementia and PD. Whether brain iron deposition is causal or secondary to the neurodegenerative processes in the general population is unclear.

METHODS

We analysed 39,533 UK Biobank participants of European genetic ancestry with brain MRI data. We studied brain iron estimated by R2* and quantitative susceptibility mapping (QSM) in 8 subcortical regions: accumbens, amygdala, caudate, hippocampus, pallidum, putamen, substantia nigra, and thalamus. We performed genome-wide associations studies (GWAS) and used Mendelian Randomization (MR) methods to estimate the causal effect of brain iron on grey matter volume, and risk of AD, non-AD and PD. We also used MR to test whether genetic liability to AD or PD causally increased brain iron (R2* and QSM).

FINDINGS

In GWAS of R2* and QSM we replicated 83% of previously reported genetic loci and identified 174 further loci across all eight brain regions. Higher genetically predicted brain iron, using both R2* and QSM, was associated with lower grey matter volumes in the caudate, putamen and thalamus (e.g., Beta-putamenQSM: -0.37, p = 2*10-46). Higher genetically predicted thalamus R2* was associated with increased risk of non-AD dementia (OR 1.36(1.16;1.60), p = 2*10-4) but not AD (p > 0.05). In males, genetically predicted putamen R2* increased non-AD dementia risk, but not in females. Higher genetically predicted iron in the caudate, putamen, and substantia nigra was associated with an increased risk of PD (Odds Ratio QSM ∼ substantia-nigra 1.21(1.07;1.37), p = 0.003). Genetic liability to AD or PD was not associated with R2* or QSM in the dementia or PD-associated regions.

INTERPRETATION

Our genetic analysis supports a causal effect of higher iron deposition in specific subcortical brain regions for Parkinson's disease, grey matter volume, and non-Alzheimer's dementia.

Alzheimer's disease approaches - Focusing on pathology, biomarkers and clinical trial candidates

The strategy for the development of new drugs for Alzheimer's disease (AD) recognizes that an effective therapy requires early therapeutic intervention and a multifactorial approach that considers the individual initiators of AD development. Current knowledge of AD includes the understanding of pathophysiology, risk factors, biomarkers, and the evolving patterns of biomarker abnormalities. This knowledge is essential in identifying potential molecular targets for new drug development. This review summarizes promising AD drug candidates, many of which are currently in phase 2 or 3 clinical trials. New agents are classified according to the Common Alzheimer's Disease Research Ontology (CADRO). The main targets of new drugs for AD are processes related to amyloid beta and tau neurotoxicity, neurotransmission, inflammation, metabolism and bioenergetics, synaptic plasticity, and oxidative stress. These interventions are aimed at preventing disease onset and slowing or eliminating disease progression. The efficacy of pharmacotherapy may be enhanced by combining these drugs with other treatments, antioxidants, and dietary supplements. Ongoing research into AD pathophysiology, risk factors, biomarkers, and the dynamics of biomarker abnormalities may contribute to the understanding of AD and offer hope for effective therapeutic strategies in the near future.

Emerging insights into Lipocalin-2: Unraveling its role in Parkinson's Disease

Parkinson's disease (PD) ranks as the second most prevalent neurodegenerative disorder globally, marked by a complex pathogenesis. Lipocalin-2 (LCN2) emerges as a crucial factor during the progression of PD. Belonging to the lipocalin family, LCN2 is integral to several biological functions, including glial cell activation, iron homeostasis regulation, immune response, inflammatory reactions, and oxidative stress mitigation. Substantial research has highlighted marked increases in LCN2 expression within the substantia nigra (SN), cerebrospinal fluid (CSF), and blood of individuals with PD. This review focuses on the pathological roles of LCN2 in neuroinflammation, aging, neuronal damage, and iron dysregulation in PD. It aims to explore the underlying mechanisms of LCN2 in the disease and potential therapeutic targets that could inform future treatment strategies.

Metal-containing nanoparticles in road dust from a Chinese megacity over the last decade: Spatiotemporal variation and driving factors

As a crucial sink of metal-containing nanoparticles (MNPs), road dust can record their spatiotemporal variations in urban environments. In this study, taking Shanghai as a representative megacity in China, a total of 272 dust samples were collected in the winter and summer of 2013 and 2021/2022 to understand the spatiotemporal variations and driving factors of MNPs. The number concentrations of Fe-, Ti-, and Zn-containing NPs were 3.8 × 106 - 8.4 × 108, 2.3 × 106-1.4 × 108, and 6.0 × 105-2.3 × 108 particles/mg, respectively, according to single particle (sp)ICP-MS analysis. These MNPs showed significantly higher number concentrations in summer than in winter. Hotspots of Fe-containing NPs were more concentrated in industrial and traffic areas, Zn-containing NPs were mainly distributed in the central urban areas, while Ti-containing NPs were abundant in areas receiving high rainfall. The structural equation model results indicates that substantial rainfall in summer can help remove MNPs from atmospheric PM2.5 into dust, while in winter industrial and traffic activities were the primary contributors for MNPs. Moreover, the contribution of traffic emissions to MNPs has surpassed industrial one over the last decade, highlighting the urgency to control traffic-sourced MNPs, especially those from non-exhaust emissions by electric vehicles.

Dopamine‑iron homeostasis interaction rescues mitochondrial fitness in Parkinson's disease

Imbalances of iron and dopamine metabolism along with mitochondrial dysfunction have been linked to the pathogenesis of Parkinson's disease (PD). We have previously suggested a direct link between iron homeostasis and dopamine metabolism, as dopamine can increase cellular uptake of iron into macrophages thereby promoting oxidative stress responses. In this study, we investigated the interplay between iron, dopamine, and mitochondrial activity in neuroblastoma SH-SY5Y cells and human induced pluripotent stem cell (hiPSC)-derived dopaminergic neurons differentiated from a healthy control and a PD patient with a mutation in the α-synuclein (SNCA) gene. In SH-SY5Y cells, dopamine treatment resulted in increased expression of the transmembrane iron transporters transferrin receptor 1 (TFR1), ferroportin (FPN), and mitoferrin2 (MFRN2) and intracellular iron accumulation, suggesting that dopamine may promote iron uptake. Furthermore, dopamine supplementation led to reduced mitochondrial fitness including decreased mitochondrial respiration, increased cytochrome c control efficiency, reduced mtDNA copy number and citrate synthase activity, increased oxidative stress and impaired aconitase activity. In dopaminergic neurons derived from a healthy control individual, dopamine showed comparable effects as observed in SH-SY5Y cells. The hiPSC-derived PD neurons harboring an endogenous SNCA mutation demonstrated altered mitochondrial iron homeostasis, reduced mitochondrial capacity along with increased oxidative stress and alterations of tricarboxylic acid cycle linked metabolic pathways compared with control neurons. Importantly, dopamine treatment of PD neurons promoted a rescue effect by increasing mitochondrial respiration, activating antioxidant stress response, and normalizing altered metabolite levels linked to mitochondrial function. These observations provide evidence that dopamine affects iron homeostasis, intracellular stress responses and mitochondrial function in healthy cells, while dopamine supplementation can restore the disturbed regulatory network in PD cells.

Polygonati Rhizoma: A review on the extraction, purification, structural characterization, biosynthesis of the main secondary metabolites and anti-aging effects

ETHNOPHARMACOLOGICAL RELEVANCE

Polygonati Rhizome (PR) is a plant that is extensively widespread in the temperate zones of the Northern Hemisphere. It is a member of the Polygonatum family of Asparagaceae. PR exhibits diverse pharmacological effects and finds applications in ethnopharmacology, serving as a potent tonic for more than two millennia. PR's compounds endow it with various pharmacological properties, including anti-aging, antioxidant, anti-fatigue, anti-inflammatory, and sleep-enhancing effects, as well as therapeutic potential for osteoporosis and age-related diseases.

AIM OF THE STUDY

This review seeks to offer a thorough overview of the processing, purification, extraction, structural characterization, and biosynthesis pathways of PR. Furthermore, it delves into the anti-aging mechanism of PR, using organ protection as an entry point.

MATERIALS AND METHODS

Information on PR was obtained from scientific databases (Google Scholar, Web of Science, ScienceDirect, SciFinder, PubMed, CNKI) and books, doctoral theses, and master's dissertations.

RESULTS

In this investigation, 49 polysaccharides were extracted from PR, and the impact of various processing, extraction, and purification techniques on the structure and activity of these polysaccharides was evaluated. Additionally, 163 saponins and 46 flavonoids were identified, and three key biosynthesis pathways of secondary metabolites were outlined. Notably, PR and Polygonat Rhizomai polysaccharides (PRP) exhibit remarkable protective effects against age-induced injuries to the brain, liver, kidney, intestine, heart, and vessels, thereby promoting longevity and ameliorating the aging process.

CONCLUSIONS

PR, a culinary and therapeutic herb, is rich in active components and pharmacological activities. Based on this review, PR plays a meaningful role in lifespan extension and anti-aging, which can be attributed to PRP. Future research should delve deeper into the structural aspects of PRP that underlie its anti-aging effects and explore potential synergistic interactions with other compounds. Moreover, exploring the potential applications of PR in functional foods and pharmaceutical formulations is recommended to advance the development of industries and resources focused on healthy aging.

Potential therapeutic natural compounds for the treatment of Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a complicated neurodegenerative disease with cognitive impairment occurring in the older people, in which extracellular accumulation of β-amyloid and intracellular aggregation of hyperphosphorylated tau are regarded as the prevailing theories. However, the exact AD mechanism has not been determined. Moreover, there is no effective treatment available in phase III trials to eradicate AD, which is imperative to explore novel treatments.

PURPOSE

A number of up-to-date pre-clinical studies on cognitive impairment is beneficial to clarify the pathology of AD. This review recapitulates several advances in AD pathobiology and discusses the neuroprotective effects of natural compounds, such as phenolic compounds, natural polysaccharides and oligosaccharides, peptide, and lipids, underscoring the therapeutic potential for AD.

METHODS

Electronic databases involving PubMed, Web of Science, and Google Scholar were searched up to October 2023. Articles were conducted using the keywords like Alzheimer's disease, pathogenic mechanisms, natural compounds, and neuroprotection.

RESULT

This review summarized several AD pathologies and the neuroprotective effects of natural compounds such as natural polysaccharides and oligosaccharides, peptide, and lipids.

CONCLUSION

We have discussed the pathogenic mechanisms of AD and the effect natural products on neurodegenerative diseases particularly in treating AD. Specifically, we investigated the molecular pathways and links between natural compounds and Alzheimer's disease such as through NF-κB, Nrf2, and mTOR pathway. Further investigation is necessary in exploring the bioactivity and effectiveness of natural compounds in clinical trials, which may provide a promising treatment for AD patients.

Altered Morpho-Functional Features of Neurogenesis in Zebrafish Embryos Exposed to Non-Combustion-Derived Magnetite

Neurogenesis is the process by which new brain cells are formed. This crucial event emerges during embryonic life and proceeds in adulthood, and it could be influenced by environmental pollution. Non-combustion-derived magnetite represents a portion of the coarse particulate matter (PM) contributing to air and water pollution in urban settings. Studies on humans have reported that magnetite and other iron oxides have significant damaging effects at a central level, where these particles accumulate and promote oxidative stress. Similarly, magnetite nanoparticles can cross the placenta and damage the embryo brain during development, but the impact on neurogenesis is still unknown. Furthermore, an abnormal Fe cation concentration in cells and tissues might promote reactive oxygen species (ROS) generation and has been associated with multiple neurodegenerative conditions. In the present study, we used zebrafish as an in vivo system to analyze the specific effects of magnetite on embryonic neurogenesis. First, we characterized magnetite using mineralogical and spectroscopic analyses. Embryos treated with magnetite at sub-lethal concentrations showed a dose-response increase in ROS in the brain, which was accompanied by a massive decrease in antioxidant genes (sod2, cat, gsr, and nrf2). In addition, a higher number of apoptotic cells was observed in embryos treated with magnetite. Next, interestingly, embryos exposed to magnetite displayed a decrease in neural staminal progenitors (nestin, sox2, and pcna markers) and a neuronal marker (elavl3). Finally, we observed significative increases in apoeb (specific microglia marker) and interleukin-1b (il1b), confirming a status of inflammation in the brain embryos treated with magnetite. Our study represents the very first in vivo evidence concerning the effects of magnetite on brain development.

Iron deposition participates in LPS-induced cognitive impairment by promoting neuroinflammation and ferroptosis in mice

Neuroinflammation is a common pathological feature and onset in multiple cognitive disorders, including postoperative cognitive dysfunction (POCD). Iron deposition was proved to participate in this process. But how iron mediates inflammation-induced cognitive deficits remains unknown. This study aimed to investigate the mechanism of iron through the neuroprotective effect of the iron chelator deferoxamine (DFO) in a mouse model of lipopolysaccharide (LPS)-induced cognitive impairment. Adult C57BL/6 mice were pretreated with 0.5 μg of DFO three days before intracerebroventricular microinjection of 2 μg of LPS. The mice showed memory deficits by showing decreased percentage of distance and the time within the platform-site quadrant, fewer platform-site crossings, and shortened swimming distance around the platform in the Morris water maze test, which were significantly mitigated by DFO pretreatment. Mechanistically, DFO prevented LPS-induced iron accumulation and modulated the imbalance of proteins expression related to iron metabolism, including elevated transferrin (TF) levels and reduced ferritin (Fth) caused by LPS. DFO attenuated the LPS-induced lipid peroxidation and oxidative stress, which is evidenced by the decrease of malondialdehyde (MDA) and lipid peroxidation (LPO) levels and the increase of superoxide dismutase (SOD) activity and glutathione (GSH) concentration. Moreover, DFO ameliorated ferroptosis-like mitochondrial damages in the hippocampus and also alleviated the expression of ferroptosis-related proteins in the hippocampus. Additionally, DFO attenuated microglial activation, alleviated LPS-induced inflammation, and reduced elevated levels of IL-6 and TNF-α in the hippocampus. Taken together, our findings suggested that DFO exerts neuroprotective effects by alleviating excessive iron participation in lipid peroxidation, reducing the occurrence of ferroptosis, inhibiting the vicious cycle between oxidative stress and inflammation, and ultimately ameliorating LPS-induced cognitive dysfunction, providing novel insights into the immunopathogenesis of inflammation-related cognitive dysfunction and future potential prevention options targeting iron.

NCOA4 initiates ferritinophagy by binding GATE16 using two highly avid short linear interaction motifs

Cells carefully regulate cytosolic iron, which is a vital enzymatic cofactor, yet is toxic in excess. In mammalian cells, surplus iron is sequestered in ferritin cages that, in iron limiting conditions, are degraded through the selective autophagy pathway ferritinophagy to liberate free iron. Prior work identified the ferritinophagy receptor protein NCOA4, which links ferritin and LC3/GABARAP-family member GATE16, effectively tethering ferritin to the autophagic machinery. Here, we elucidate the molecular mechanism underlying this interaction, discovering two short linear motifs in NCOA4 that each bind GATE16 with weak affinity. These binding motifs are highly avid and, in concert, support high-affinity NCOA4•GATE16 complex formation. We further find the minimal NCOA4383-522 fragment bearing these motifs is sufficient for ferritinophagy and that both motifs are necessary for this activity. This work suggests a general mechanism wherein selective autophagy receptors can distinguish between the inactive soluble pools of LC3/GABARAPs and the active membrane-conjugated forms that drive autophagy. Finally, we find that iron decreases NCOA4383-522's affinity for GATE16, providing a plausible mechanism for iron-dependent regulation of ferritinophagy.

Experimental verification about treatment of Bu-Shen-Yi-Jing-Fang in Alzheimer's disease by the analysis of the feasible signaling pathway of network pharmacology

CONTEXT

Bu-shen-yi-jing-fang (BSYJF) has been reported to reduce amyloid-β (Aβ)1-42 deposition in the brain of APP/PS1 mice and ameliorate cognitive function. However, its neuroprotective mechanism remains unclear.

OBJECTIVE

This study aims to investigate whether BSYJF exerts a protective effect on Aβ1-42-induced oxidative stress injury and explore its possible mechanism.

MATERIALS AND METHODS

The platform databases TCMSP, Swiss, TTD, DrugBank, and GeneCards were used to mine the targets of Alzheimer's disease (AD) and BSYJF. The platform databases STRING and Metascape were used to build the interaction network of the target protein, and Cytoscape software was used to analyze this network and screen out the key pathways. Aβ1-42-treated SKNMC cells were established to verify the mechanism of BSYJF and the key proteins. The downstream proteins and antioxidants as well as apoptosis and ferroptosis of the PI3K/AKT/Nrf2 signaling pathway were validated using an in vitro SKNMC cell model experiment. The expression levels of related proteins were detected using Western blotting. Flow cytometry and immunofluorescence staining were used to analyze apoptosis and ferroptosis.

RESULTS

Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis considered the key signal pathways, mainly involving the PI3K/AKT signaling pathway. Experimental validation demonstrated that BSYJF treatment markedly increased the activity of the PI3K/AKT pathway, which could exert anti-AD effects.

CONCLUSIONS

Our data provided compelling evidence that the protective effects of BSYJF might be associated with their regulation of the PI3K/AKT/Nrf2 signaling pathway. These studies offered a potential therapy for natural herbal medicine treatment of AD.

Tau accumulation is associated with dopamine deficiency in vivo in four-repeat tauopathies

PURPOSE

We hypothesized that severe tau burden in brain regions involved in direct or indirect pathways of the basal ganglia correlate with more severe striatal dopamine deficiency in four-repeat (4R) tauopathies. Therefore, we correlated [18F]PI-2620 tau-positron-emission-tomography (PET) imaging with [123I]-Ioflupane single-photon-emission-computed tomography (SPECT) for dopamine transporter (DaT) availability.

METHODS

Thirty-eight patients with clinically diagnosed 4R-tauopathies (21 male; 69.0 ± 8.5 years) and 15 patients with clinically diagnosed α-synucleinopathies (8 male; 66.1 ± 10.3 years) who underwent [18F]PI-2620 tau-PET and DaT-SPECT imaging with a time gap of 3 ± 5 months were evaluated. Regional Tau-PET signals and DaT availability as well as their principal components were correlated in patients with 4R-tauopathies and α-synucleinopathies. Both biomarkers and the residuals of their association were correlated with clinical severity scores in 4R-tauopathies.

RESULTS

In patients with 4R-tauopathies, [18F]PI-2620 binding in basal ganglia and midbrain regions was negatively associated with striatal DaT availability (i.e. globus pallidus internus and putamen (β =  - 0.464, p = 0.006, Durbin-Watson statistics = 1.824) in a multiple regression model. Contrarily, [18F]PI-2620 binding in the dentate nucleus showed no significant regression factor with DaT availability in the striatum (β = 0.078, p = 0.662, Durbin-Watson statistics = 1.686). Patients with α-synucleinopathies did not indicate any regional associations between [18F]PI-2620-binding and DaT availability. Higher DaT-SPECT binding relative to tau burden was associated with better clinical performance (β =  - 0.522, p = 0.011, Durbin-Watson statistics = 2.663) in patients with 4R-tauopathies.

CONCLUSION

Tau burden in brain regions involved in dopaminergic pathways is associated with aggravated dopaminergic dysfunction in patients with clinically diagnosed primary tauopathies. The ability to sustain dopamine transmission despite tau accumulation may preserve motor function.

The role of labile iron on brain proteostasis; could it be an early event of neurodegenerative disease?

Iron deposits in the brain are a natural consequence of aging. Iron accumulation, especially in the form of labile iron, can trigger a cascade of adverse effects, eventually leading to neurodegeneration and cognitive decline. Aging also increases the dysfunction of cellular proteostasis. The question of whether iron alters proteostasis is now being pondered. Herein, we investigated the effect of ferric citrate, considered as labile iron, on various aspects of proteostasis of neuronal cell lines, and also established an animal model having a labile iron diet in order to evaluate proteostasis alteration in the brain along with behavioral effects. According to an in vitro study, labile iron was found to activate lysosome formation but inhibits lysosomal clearance function. Furthermore, the presence of labile iron can alter autophagic flux and can also induce the accumulation of protein aggregates. RNA-sequencing analysis further reveals the upregulation of various terms related to proteostasis along with neurodegenerative disease-related terms. According to an in vivo study, a labile iron-rich diet does not induce iron overload conditions and was not detrimental to the behavior of male Wistar rats. However, an iron-rich diet can promote iron accumulation in a region-dependent manner. By staining for autophagic markers and misfolding proteins in the cerebral cortex and hippocampus, an iron-rich diet was actually found to alter autophagy and induce an accumulation of misfolding proteins. These findings emphasize the importance of labile iron on brain cell proteostasis, which could be implicated in developing of neurological diseases.

A commentary on studies of brain iron accumulation during ageing

Brain iron content is widely reported to increase during "ageing", across multiple species from nematodes, rodents (mice and rats) and humans. Given the redox-active properties of iron, there has been a large research focus on iron-mediated oxidative stress as a contributor to tissue damage during natural ageing, and also as a risk factor for neurodegenerative disease. Surprisingly, however, the majority of published studies have not investigated brain iron homeostasis during the biological time period of senescence, and thus knowledge of how brain homeostasis changes during this critical stage of life largely remains unknown. This commentary examines the literature published on the topic of brain iron homeostasis during ageing, providing a critique on limitations of currently used experimental designs. The commentary also aims to highlight that although much research attention has been given to iron accumulation or iron overload as a pathological feature of ageing, there is evidence to support functional iron deficiency may exist, and this should not be overlooked in studies of ageing or neurodegenerative disease.

Deferasirox exerts anti-epileptic effects by improving brain iron homeostasis via regulation of ITPRIP

Epilepsy constitutes a global health concern, affecting millions of individuals and approximately one-third of patients exhibit drug resistance. Recent investigations have revealed alterations in cerebral iron content in both epilepsy patients and animal models. However, the extant literature lacks a comprehensive exploration into the ramifications of modulating iron homeostasis as an intervention in epilepsy. This study investigated the impact of deferasirox, a iron ion chelator, on epilepsy. This study unequivocally substantiated the antiepileptic efficacy of deferasirox in a kainic acid-induced epilepsy model. Furthermore, deferasirox administration mitigated seizure susceptibility in a pentylenetetrazol-induced kindling model. Conversely, the augmentation of iron levels through supplementation has emerged as a potential exacerbating factor in the precipitating onset of epilepsy. Intriguingly, our investigation revealed a hitherto unreported discovery: ITPRIP was identified as a pivotal modulator of excitatory synaptic transmission, regulating seizures in response to deferasirox treatment. In summary, our findings indicate that deferasirox exerts its antiepileptic effects through the precise targeting of ITPRIP and amelioration of cerebral iron homeostasis, suggesting that deferasirox is a promising and novel therapeutic avenue for interventions in epilepsy.

PPP2CA Inhibition Promotes Ferroptosis Sensitivity Through AMPK/SCD1 Pathway in Colorectal Cancer

PURPOSE

Colorectal cancer (CRC) is a very common malignancy of the digestive system. Despite a variety of treatments including surgery, chemotherapeutic and targeted drugs, the prognosis for patients with CRC is still unsatisfactory and the mortality remains high. Protein phosphorylation plays an essential role in tumorigenesis and progression and is also crucial for protein to act with proper functions. Ferroptosis is found widely involved in various diseases especially tumors as a newly identified programmed cell death.

METHODS

In our study, we aimed at PPP2CA as a prospective target which may play a crucial role in CRC progression. In one hand, knockdown of PPP2CA significantly enhanced the malignant phenotype in HCT116. In the other hand, knockdown of PPP2CA significantly enhanced Erastin-induced ferroptosis as well.

RESULTS

Specifically, knockdown of PPP2CA in HCT116 significantly increased the relative level of malondialdehyde (MDA), reactive oxygen species (ROS) and Fe2+, and decreased GSH/GSSG ratio after the treatment of certain concentration of Erastin. Besides, we found that the inhibition of PPP2CA further led to the suppression of SCD1 expression in CRC cells in a AMPK-dependent way.

CONCLUSION

Ultimately, we conclude that PPP2CA may regulate Erastin-induced ferroptosis through AMPK/SCD1 signaling pathway.

Association of plasma lactoferrin levels with disease severity in glaucoma patients

Objective

To explore the relationship between plasma lactoferrin (Lf) and glaucoma, assessing the clinical utility of Lf in glaucoma.

Methods

A cross-sectional study involved 161 glaucoma patients and 115 healthy controls, with a follow-up of 14 subjects after approximately 2 years. Plasma Lf markers were quantified using ELISA, comparing levels between glaucoma patients and healthy controls, and analyzing plasma Lf across different glaucoma severity grades.

Results

Glaucoma patients had significantly elevated plasma Lf levels compared to healthy controls (p < 0.001). Higher plasma Lf levels correlated with more severe disease stages (HPA grades showed ρ = 0.435, p < 0.001; AGIS grades showed ρ = 0.436, p < 0.001) and reduced retinal nerve fiber layer (RNFL) thickness (RNFL thickness showed ρ = -0.204, p = 0.024). ROC curve analysis demonstrated the efficacy of glaucoma markers in differentiating early-stage from advanced glaucoma.

Conclusion

Plasma Lf levels are significantly associated with glaucoma severity and may be involved in the pathogenic progression of the disease.

Iron deposition in subcortical nuclei of Parkinson's disease: A meta-analysis of quantitative iron-sensitive magnetic resonance imaging studies

BACKGROUND

Iron deposition plays a crucial role in the pathophysiology of Parkinson's disease (PD), yet the distribution pattern of iron deposition in the subcortical nuclei has been inconsistent across previous studies. We aimed to assess the difference patterns of iron deposition detected by quantitative iron-sensitive magnetic resonance imaging (MRI) between patients with PD and patients with atypical parkinsonian syndromes (APSs), and between patients with PD and healthy controls (HCs).

METHODS

A systematic literature search was conducted on PubMed, Embase, and Web of Science databases to identify studies investigating the iron content in PD patients using the iron-sensitive MRI techniques (R2* and quantitative susceptibility mapping [QSM]), up until May 1, 2023. The quality assessment of case-control and cohort studies was performed using the Newcastle-Ottawa Scale, whereas diagnostic studies were assessed using the Quality Assessment of Diagnostic Accuracy Studies-2. Standardized mean differences and summary estimates of sensitivity, specificity, and area under the curve (AUC) were calculated for iron content, using a random effects model. We also conducted the subgroup-analysis based on the MRI sequence and meta-regression.

RESULTS

Seventy-seven studies with 3192 PD, 209 multiple system atrophy (MSA), 174 progressive supranuclear palsy (PSP), and 2447 HCs were included. Elevated iron content in substantia nigra (SN) pars reticulata (P <0.001) and compacta (P <0.001), SN (P <0.001), red nucleus (RN, P <0.001), globus pallidus (P <0.001), putamen (PUT, P = 0.009), and thalamus (P = 0.046) were found in PD patients compared with HCs. PD patients showed lower iron content in PUT (P <0.001), RN (P = 0.003), SN (P = 0.017), and caudate nucleus (P = 0.027) than MSA patients, and lower iron content in RN (P = 0.001), PUT (P <0.001), globus pallidus (P = 0.004), SN (P = 0.015), and caudate nucleus (P = 0.001) than PSP patients. The highest diagnostic accuracy distinguishing PD from HCs was observed in SN (AUC: 0.85), and that distinguishing PD from MSA was found in PUT (AUC: 0.90). In addition, the best diagnostic performance was achieved in the RN for distinguishing PD from PSP (AUC: 0.84).

CONCLUSION

Quantitative iron-sensitive MRI could quantitatively detect the iron content of subcortical nuclei in PD and APSs, while it may be insufficient to accurately diagnose PD. Future studies are needed to explore the role of multimodal MRI in the diagnosis of PD.

REGISTRISION

PROSPERO; CRD42022344413.

Could Alcohol-Related Cognitive Decline Be the Result of Iron-Induced Neuroinflammation?

Excessive and prolonged alcohol use can have long-term severe neurological consequences. The mechanisms involved may be complicated; however, new evidence seems to indicate the involvement of iron accumulation and neuroinflammation. Prolonged alcohol consumption has been linked to the accumulation of iron in specific regions of the brain. Evidence suggests that excess iron in the brain can trigger microglia activation in response. This activation leads to the release of pro-inflammatory cytokines and reactive oxygen species, which can cause damage to neurons and surrounding brain tissue. Additionally, iron-induced oxidative stress and inflammation can disrupt the blood-brain barrier, allowing immune cells from the periphery to infiltrate the brain. This infiltration can lead to further neuroinflammatory responses. Inflammation in the brain subsequently disrupts neuronal networks, impairs synaptic plasticity, and accelerates neuronal cell death. Consequently, cognitive functions such as memory, attention, and decision-making are compromised. Additionally, chronic neuroinflammation can hasten the development and progression of neurodegenerative diseases, further exacerbating cognitive impairment. Therefore, alcohol could act as a trigger for iron-induced neuroinflammation and cognitive decline. Overall, the mechanisms at play here seem to strongly link alcohol with cognitive decline, with neuroinflammation resulting from alcohol-induced iron accumulation playing a pivotal role.

Inflammation subsequent to mild iron excess differentially alters regional brain iron metabolism, oxidation and neuroinflammation status in mice

Iron dyshomeostasis and neuroinflammation, characteristic features of the aged brain, and exacerbated in neurodegenerative disease, may induce oxidative stress-mediated neurodegeneration. In this study, the effects of potential priming with mild systemic iron injections on subsequent lipopolysaccharide (LPS)-induced inflammation in adult C57Bl/6J mice were examined. After cognitive testing, regional brain tissues were dissected for iron (metal) measurements by total reflection X-ray fluorescence and synchrotron radiation X-Ray fluorescence-based elemental mapping; and iron regulatory, ferroptosis-related, and glia-specific protein analysis, and lipid peroxidation by western blotting. Microglial morphology and astrogliosis were assessed by immunohistochemistry. Iron only treatment enhanced cognitive performance on the novel object location task compared with iron priming and subsequent LPS-induced inflammation. LPS-induced inflammation, with or without iron treatment, attenuated hippocampal heme oxygenase-1 and augmented 4-hydroxynonenal levels. Conversely, in the cortex, elevated ferritin light chain and xCT (light chain of System Xc-) were observed in response to LPS-induced inflammation, without and with iron-priming. Increased microglial branch/process lengths and astrocyte immunoreactivity were also increased by combined iron and LPS in both the hippocampus and cortex. Here, we demonstrate iron priming and subsequent LPS-induced inflammation led to iron dyshomeostasis, compromised antioxidant function, increased lipid peroxidation and altered neuroinflammatory state in a brain region-dependent manner.

An automated hybrid approach via deep learning and radiomics focused on the midbrain and substantia nigra to detect early-stage Parkinson's disease

Objectives

The altered neuromelanin in substantia nigra pars compacta (SNpc) is a valuable biomarker in the detection of early-stage Parkinson's disease (EPD). Diagnosis via visual inspection or single radiomics based method is challenging. Thus, we proposed a novel hybrid model that integrates radiomics and deep learning methodologies to automatically detect EPD based on neuromelanin-sensitive MRI, namely short-echo-time Magnitude (setMag) reconstructed from quantitative susceptibility mapping (QSM).

Methods

In our study, we collected QSM images including 73 EPD patients and 65 healthy controls, which were stratified into training-validation and independent test sets with an 8:2 ratio. Twenty-four participants from another center were included as the external validation set. Our framework began with the detection of the brainstem utilizing YOLO-v5. Subsequently, a modified LeNet was applied to obtain deep learning features. Meanwhile, 1781 radiomics features were extracted, and 10 features were retained after filtering. Finally, the classified models based on radiomics features, deep learning features, and the hybrid of both were established through machine learning algorithms, respectively. The performance was mainly evaluated using accuracy, net reclassification improvement (NRI), and integrated discrimination improvement (IDI). The saliency map was used to visualize the model.

Results

The hybrid feature-based support vector machine (SVM) model showed the best performance, achieving ACC of 96.3 and 95.8% in the independent test set and external validation set, respectively. The model established by hybrid features outperformed the one radiomics feature-based (NRI: 0.245, IDI: 0.112). Furthermore, the saliency map showed that the bilateral "swallow tail" sign region was significant for classification.

Conclusion

The integration of deep learning and radiomic features presents a potent strategy for the computer-aided diagnosis of EPD. This study not only validates the accuracy of our proposed model but also underscores its interpretability, evidenced by differential significance across various anatomical sites.

General anesthetic agents induce neurotoxicity through oligodendrocytes in the developing brain

General anesthetic agents can impact brain function through interactions with neurons and their effects on glial cells. Oligodendrocytes perform essential roles in the central nervous system, including myelin sheath formation, axonal metabolism, and neuroplasticity regulation. They are particularly vulnerable to the effects of general anesthetic agents resulting in impaired proliferation, differentiation, and apoptosis. Neurologists are increasingly interested in the effects of general anesthetic agents on oligodendrocytes. These agents not only act on the surface receptors of oligodendrocytes to elicit neuroinflammation through modulation of signaling pathways, but also disrupt metabolic processes and alter the expression of genes involved in oligodendrocyte development and function. In this review, we summarize the effects of general anesthetic agents on oligodendrocytes. We anticipate that future research will continue to explore these effects and develop strategies to decrease the incidence of adverse reactions associated with the use of general anesthetic agents.

Putamen iron quantification in diseases with neurodegeneration: a meta-analysis of the quantitative susceptibility mapping technique

Quantitative susceptibility mapping (QSM) is an MRI technique that accurately measures iron concentration in brain tissues. This meta-analysis synthesized evidence from 30 studies that used QSM to quantify the iron levels in the putamen. The PRISMA statement was adhered to when conducting the systematic reviews and meta-analyses. We conducted a meta-analysis using a random-effects model, as well as subgroup analyses (disease type, geographic region, field strength, coil, disease type, age, and sex) and sensitivity analysis. A total of 1247 patients and 1035 controls were included in the study. Pooled results showed a standardized mean difference (SMD) of 0.41 (95% CI 0.19 to 0.64), with the strongest effect seen in Alzheimer's disease (AD) at 1.01 (95% CI 0.50 to 1.52). Relapsing-remitting multiple sclerosis (RRMS) also showed increased putaminal iron at 0.37 (95% CI 0.177 to 0.58). No significant differences were observed in Parkinson's disease (PD). No significant differences were found between subgroups based on geographic region, field strength, coil, disease type, age, and sex. The studies revealed significant heterogeneity, with field strength as the primary source, while other factors, such as disease type, location, age, sex, and coil type, may have contributed. The sensitivity analysis showed that these factors did not have a significant influence on the overall results. In summary, this meta-analysis supports abnormalities in putaminal iron content across different diseases with neurodegeneration, especially AD and RRMS, as measured by QSM. This highlights the potential of QSM as an imaging biomarker to better understand disease mechanisms involving disturbances in brain iron homeostasis.

In vitro heterochronic parabiosis identifies pigment epithelium-derived factor as a systemic mediator of rejuvenation by young blood

Several decades of heterochronic parabiosis (HCPB) studies have demonstrated the restorative impact of young blood, and deleterious influence of aged blood, on physiological function and homeostasis across tissues, although few of the factors responsible for these observations have been identified. Here we develop an in vitro HCPB system to identify these circulating factors, using replicative lifespan (RLS) of primary human fibroblasts as an endpoint of cellular health. We find that RLS is inversely correlated with serum donor age and sensitive to the presence or absence of specific serum components. Through in vitro HCPB, we identify the secreted protein pigment epithelium-derived factor (PEDF) as a circulating factor that extends RLS of primary human fibroblasts and declines with age in mammals. Systemic administration of PEDF to aged mice reverses age-related functional decline and pathology across several tissues, improving cognitive function and reducing hepatic fibrosis and renal lipid accumulation. Together, our data supports PEDF as a systemic mediator of the effect of young blood on organismal health and homeostasis and establishes our in vitro HCPB system as a valuable screening platform for the identification of candidate circulating factors involved in aging and rejuvenation.

Hybrid molecules synergistically mitigate ferroptosis and amyloid-associated toxicities in Alzheimer's disease

Alzheimer's disease (AD) is a neurodegenerative disorder characterized by the build-up of extracellular amyloid β (Aβ) plaques and intracellular neurofibrillary tangles (NFTs). Ferroptosis, an iron (Fe)-dependent form of cell death plays a significant role in the multifaceted AD pathogenesis through generation of reactive oxygen species (ROS), mitochondrial damage, lipid peroxidation, and reduction in glutathione peroxidase 4 (GPX4) enzyme activity and levels. Aberrant liquid-liquid phase separation (LLPS) of tau drives the growth and maturation of NFTs contributing to AD pathogenesis. In this study, we strategically combined the structural and functional properties of gallic acid (GA) and cyclic dipeptides (CDPs) to synthesize hybrid molecules that effectively target both ferroptosis and amyloid toxicity in AD. This innovative approach marks a paradigm shift from conventional therapeutic strategies. This is the first report of a synthetic small molecule (GCTR) that effectively combats ferroptosis, simultaneously restoring enzymatic activity and enhancing cellular levels of its master regulator, GPX4. Further, GCTR disrupts Fe3+-induced LLPS of tau, and aids in attenuation of abnormal tau fibrillization. The synergistic action of GCTR in combating both ferroptosis and amyloid toxicity, bolstered by GPX4 enhancement and modulation of Fe3+-induced tau LLPS, holds promise for the development of small molecule-based novel therapeutics for AD.

Nontargeted metabolomics reveals sequential changes in amino acid and ferroptosis-related metabolism in Parkinson's disease

Parkinson's disease (PD) is inseparable from metabolic disorders but lacks assessment of specific metabolite alteration. To explore the sequential metabolic changes in PD progression, we evenly divided 78 C57BL/6 mice (10 weeks) into six groups (one control group and five experimental groups) and collected the hippocampus tissue of mice after treating with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, and probenecid (twice a week) at five periods (1, 2, 3, 4, and 5 weeks) for metabolome analysis. Our study identified 567 differentially abundant metabolites (DAMs) (total 4348 metabolites). Compared with controls, 145, 146, 171, 208, and 213 DAMs were obtained from the five experimental groups, respectively. Notably, 40 shared DAMs were present in five experimental groups, of which 22 shared DAMs formed a new metabolic network based on amino acid metabolism. Compared with group W3, 84 DAMs were identified in group W5, including 12 unique DAMs. DAMs in different stages of PD were significantly enriched in amino acid metabolism pathway, lipid metabolism pathway, and ferroptosis pathway. l-Glutamine, spermidine, and l-tryptophan were the key hubs in the whole metabolic process of PD. N-Formyl-l-methionine gradually increased in abundance with PD progression, whereas 5-methylcytosine gradually decreased. The study emphasized the sequential changes in DAMs in PD progression, stimulating subsequent studies.

How close are we to a breakthrough? The hunt for blood biomarkers in Parkinson's disease diagnosis

Parkinson's disease (PD), being the second largest neurodegenerative disease, poses challenges in early detection, resulting in a lack of timely treatment options to effectively manage the disease. By the time clinical diagnosis becomes possible, more than 60% of dopamine neurons in the substantia nigra (SN) of patients have already degenerated. Therefore, early diagnosis or identification of warning signs is crucial for the prompt and timely beginning of the treatment. However, conducting invasive or complex diagnostic procedures on asymptomatic patients can be challenging, making routine blood tests a more feasible approach in such cases. Numerous studies have been conducted over an extended period to search for effective diagnostic biomarkers in blood samples. However, thus far, no highly effective biomarkers have been confirmed. Besides classical proteins like α-synuclein (α-syn), phosphorylated α-syn and oligomeric α-syn, other molecules involved in disease progression should also be given equal attention. In this review, we will not only discuss proposed biomarkers that are currently under investigation but also delve into the mechanisms underlying the disease, focusing on processes such as α-syn misfolding, intercellular transmission and the crossing of the blood-brain barrier (BBB). Our aim is to provide an updated overview of molecules based on these processes that may potentially serve as blood biomarkers.

Spatiotemporal patterns of brain iron-oxygen metabolism in patients with Parkinson's disease

OBJECTIVES

Iron deposition and mitochondrial dysfunction are closely associated with the genesis and progression of Parkinson's disease (PD). This study aims to extract susceptibility and oxygen extraction fraction (OEF) values of deep grey matter (DGM) to explore spatiotemporal progression patterns of brain iron-oxygen metabolism in PD.

METHODS

Ninety-five PD patients and forty healthy controls (HCs) were included. Quantitative susceptibility mapping (QSM) and OEF maps were computed from MRI multi-echo gradient echo data. Analysis of covariance (ANCOVA) was used to compare mean susceptibility and OEF values in DGM between early-stage PD (ESP), advanced-stage PD (ASP) patients and HCs. Then Granger causality analysis on the pseudo-time-series of MRI data was applied to assess the causal effect of early altered nuclei on iron content and oxygen extraction in other DGM nuclei.

RESULTS

The susceptibility values in substantia nigra (SN), red nucleus, and globus pallidus (GP) significantly increased in PD patients compared with HCs, while the iron content in GP did not elevate obviously until the late stage. The mean OEF values for the caudate nucleus, putamen, and dentate nucleus were higher in ESP patients than in ASP patients or/and HCs. We also found that iron accumulation progressively expands from the midbrain to the striatum. These alterations were correlated with clinical features and improved AUC for early PD diagnosis to 0.824.

CONCLUSIONS

Abnormal cerebral iron deposition and tissue oxygen utilization in PD measured by QSM and OEF maps could reflect pathological alterations in neurodegenerative processes and provide valuable indicators for disease identification and management.

CLINICAL RELEVANCE STATEMENT

Noninvasive assessment of cerebral iron-oxygen metabolism may serve as clinical evidence of pathological changes in PD and improve the validity of diagnosis and disease monitoring.

KEY POINTS

• Quantitative susceptibility mapping and oxygen extraction fraction maps indicated the cerebral pathology of abnormal iron accumulation and oxygen metabolism in Parkinson's disease. • Iron deposition is mainly in the midbrain, while altered oxygen metabolism is concentrated in the striatum and cerebellum. • The susceptibility and oxygen extraction fraction values in subcortical nuclei were associated with clinical severity.

New insights on neurodegeneration triggered by iron accumulation: Intersections with neutral lipid metabolism, ferroptosis, and motor impairment

Brain iron accumulation constitutes a pathognomonic indicator in several neurodegenerative disorders. Metal accumulation associated with dopaminergic neuronal death has been documented in Parkinson's disease. Through the use of in vivo and in vitro models, we demonstrated that lipid dysregulation manifests as a neuronal and glial response during iron overload. In this study, we show that cholesterol content and triacylglycerol (TAG) hydrolysis were strongly elevated in mice midbrain. Lipid cacostasis was concomitant with the loss of dopaminergic neurons, astrogliosis and elevated expression of α-synuclein. Exacerbated lipid peroxidation and markers of ferroptosis were evident in the midbrain from mice challenged with iron overload. An imbalance in the activity of lipolytic and acylation enzymes was identified, favoring neutral lipid hydrolysis, and consequently reducing TAG and cholesteryl ester levels. Notably, these observed alterations were accompanied by motor impairment in iron-treated mice. In addition, neuronal and glial cultures along with their secretomes were used to gain further insight into the mechanism underlying TAG hydrolysis and cholesterol accumulation as cellular responses to iron accumulation. We demonstrated that TAG hydrolysis in neurons is triggered by astrocyte secretomes. Moreover, we found that the ferroptosis inhibitor, ferrostatin-1, effectively prevents cholesterol accumulation both in neurons and astrocytes. Taken together, these results indicate that lipid disturbances occur in iron-overloaded mice as a consequence of iron-induced oxidative stress and depend on neuron-glia crosstalk. Our findings suggest that developing therapies aimed at restoring lipid homeostasis may lead to specific treatment for neurodegeneration associated with ferroptosis and brain iron accumulation.

Brain iron concentration in childhood ADHD: A systematic review of neuroimaging studies

Iron deficiency may play a role in the pathophysiology of Attention Deficit/Hyperactivity Disorder (ADHD). Due to its preponderant function in monoamine catecholamine and myelin synthesis, brain iron concentration may be of primary interest in the investigation of iron dysregulation in ADHD. This study reviewed current evidence of brain iron abnormalities in children and adolescents with ADHD using magnetic resonance imaging methods, such as relaxometry and quantitative susceptibility mapping, to assess brain iron estimates. The study was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. A literature search was performed for studies published between January 1, 2008 and July 7, 2023 in Medline, Scopus and Proquest. Regions of interest, brain iron index values and phenotypical information were extracted from the relevant studies. Risk of bias was assessed using a modified version of the National Heart, Lung, and Blood Institute quality assessment tool. Seven cross-sectional studies comparing brain iron estimates in children with ADHD with neurotypical children were included. Significantly reduced brain iron content in medication-naïve children with ADHD was a consistent finding. Two studies found psychostimulant use may increase and normalize brain iron concentration in children with ADHD. The findings were consistent across the studies despite differing methodologies and may lay the early foundation for the recognition of a potential biomarker in ADHD, although longitudinal prospective neuroimaging studies using larger sample sizes are required. Lastly, the effects of iron supplementation on brain iron concentration in children with ADHD need to be elucidated.

Child and Adolescent Manganese Biomarkers and Adolescent Postural Balance in Marietta CARES Cohort Participants

BACKGROUND

Manganese (Mn) plays a significant role in both human health and global industries. Epidemiological studies of exposed populations demonstrate a dose-dependent association between Mn and neuromotor effects ranging from subclinical effects to a clinically defined syndrome. However, little is known about the relationship between early life Mn biomarkers and adolescent postural balance.

OBJECTIVES

This study investigated the associations between childhood and adolescent Mn biomarkers and adolescent postural balance in participants from the longitudinal Marietta Communities Actively Researching Exposures Study (CARES) cohort.

METHODS

Participants were recruited into CARES when they were 7-9 y old, and reenrolled at 13-18 years of age. At both time points, participants provided samples of blood, hair, and toenails that were analyzed for blood Mn and lead (Pb), serum cotinine, hair Mn, and toenail Mn. In adolescence, participants completed a postural balance assessment. Greater sway indicates postural instability (harmful effect), whereas lesser sway indicates postural stability (beneficial effect). Multivariable linear regression models were conducted to investigate the associations between childhood and adolescent Mn biomarkers and adolescent postural balance adjusted for age, sex, height-weight ratio, parent/caregiver intelligence quotient, socioeconomic status, blood Pb, and serum cotinine.

RESULTS

CARES participants who completed the adolescent postural balance assessment (n = 123 ) were 98% White and 54% female and had a mean age of 16 y (range: 13-18 y). In both childhood and adolescence, higher Mn biomarker concentrations were significantly associated with greater adolescent sway measures. Supplemental analyses revealed sex-specific associations; higher childhood Mn biomarker concentrations were significantly associated with greater sway in females compared with males.

DISCUSSION

This study found childhood and adolescent Mn biomarkers were associated with subclinical neuromotor effects in adolescence. This study demonstrates postural balance as a sensitive measure to assess the association between Mn biomarkers and neuromotor function. https://doi.org/10.1289/EHP13381.

Iron retardation in lysosomes protects senescent cells from ferroptosis

Ferroptosis, an iron-triggered modality of cellular death, has been reported to closely relate to human aging progression and aging-related diseases. However, the involvement of ferroptosis in the development and maintenance of senescent cells still remains elusive. Here, we established a doxorubicin-induced senescent HSkM cell model and found that both iron accumulation and lipid peroxidation increase in senescent cells. Moreover, such iron overload in senescent cells has changed the expression panel of the ferroptosis-response proteins. Interestingly, the iron accumulation and lipid peroxidation does not trigger ferroptosis-induced cell death. Oppositely, senescent cells manifest resistance to the ferroptosis inducers, compared to the proliferating cells. To further investigate the mechanism of ferroptosis-resistance for senescent cells, we traced the iron flux in cell and found iron arrested in lysosome. Moreover, disruption of lysosome functions by chloroquine and LLOMe dramatically triggered the senescent cell death. Besides, the ferroitinophagy-related proteins FTH1/FTL and NCOA4 knockdown also increases the senescent cell death. Thus, we speculated that iron retardation in lysosome of senescent cells is the key mechanism for ferroptosis resistance. And the lysosome is a promising target for senolytic drugs to selectively clear senescent cells and alleviate the aging related diseases.

The role of ferroptosis as a regulator of oxidative stress in the pathogenesis of ischemic stroke

Ferroptosis is a unique form of cell death that was first described in 2012 and plays a significant role in various diseases, including neurodegenerative conditions. It depends on a dysregulation of cellular iron metabolism, which increases free, redox-active, iron that can trigger Fenton reactions, generating hydroxyl radicals that damage cells through oxidative stress and lipid peroxidation. Lipid peroxides, resulting mainly from unsaturated fatty acids, damage cells by disrupting membrane integrity and propagating cell death signals. Moreover, lipid peroxide degradation products can further affect cellular components such as DNA, proteins, and amines. In ischemic stroke, where blood flow to the brain is restricted, there is increased iron absorption, oxidative stress, and compromised blood-brain barrier integrity. Imbalances in iron-transport and -storage proteins increase lipid oxidation and contribute to neuronal damage, thus pointing to the possibility of brain cells, especially neurons, dying from ferroptosis. Here, we review the evidence showing a role of ferroptosis in ischemic stroke, both in recent studies directly assessing this type of cell death, as well as in previous studies showing evidence that can now be revisited with our new knowledge on ferroptosis mechanisms. We also review the efforts made to target ferroptosis in ischemic stroke as a possible treatment to mitigate cellular damage and death.

Genetic markers associated with ferroptosis in Alzheimer's disease

Objective

Ferroptosis is implicated in the pathogenesis of neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease, and vascular dementia, implying that it may have a regulatory effect on the progression of these diseases. However, the specific role of ferroptosis-related genes (FRGs) in Alzheimer's disease (AD) is not yet fully understood. The aim of the study was to detect ferroptosis related genes with regulatory functions in the disease and explore potential mechanisms in AD.

Methods

Hub FRGs were obtained through multiple algorithms based on the GSE5281 dataset. The screening process was implemented by R packages including limma, WGCNA, glm and SVM-RFE. Gene Ontology classification and pathway enrichment analysis were performed based on FRGs. Biological processes involved with hub FRGs were investigated through GSVA and GSEA methods. Immune infiltration analysis was performed by the R package CIBERSORT. Receiver operating characteristic curve (ROC) was utilized to validate the accuracy of hub FRGs. The CeRNA network attempted to find non-coding RNA transcripts which may play a role in disease progression.

Results

DDIT4, MUC1, KLHL24, CD44, and RB1 were identified as hub FRGs. As later revealed by enrichment analysis, the hub FRGs had important effects on AD through involvement in diverse AD pathogenesis-related pathways such as autophagy and glutathione metabolism. The immune microenvironment in AD shows increased numbers of resting NK cells, macrophages, and mast cells, with decreased levels of CD8 T cells when compared to healthy samples. Regulatory T cells were positively correlated with MUC1, KLHL24, and DDIT4 expression, while RB1 showed negative correlations with eosinophils and CD8 T cells, suggesting potential roles in modulating the immune environment in AD.

Conclusion

Our research has identified five hub FRGs in AD. We concluded that ferroptosis may be involved in the disease.

Integrated Short-TE and Hadamard-edited Multi-Sequence (ISTHMUS) for Advanced MRS

Background

To examine data quality and reproducibility using ISTHMUS, which has been implemented as the standardized MR spectroscopy sequence for the multi-site Healthy Brain and Child Development (HBCD) study.

Methods

ISTHMUS is the consecutive acquisition of short-TE PRESS (32 transients) and long-TE HERCULES (224 transients) data with dual-TE water reference scans. Voxels were positioned in the centrum semiovale, dorsal anterior cingulate cortex, posterior cingulate cortex and bilateral thalamus regions. After acquisition, ISTHMUS data were separated into the PRESS and HERCULES portions for analysis and modeled separately using Osprey. In vivo experiments were performed in 10 healthy volunteers (6 female; 29.5±6.6 years). Each volunteer underwent two scans on the same day. Differences in metabolite measurements were examined. T2 correction based on the dual-TE water integrals were compared with: 1) T2 correction based the default white matter and gray matter T2 reference values in Osprey; 2) shorter WM and GM T2 values from recent literature; and 3) reduced CSF fractions.

Results

No significant difference in linewidth was observed between PRESS and HERCULES. Bilateral thalamus spectra had produced significantly higher (p<0.001) linewidth compared to the other three regions. Linewidth measurements were similar between scans, with scan-to-scan differences under 1 Hz for most subjects. Paired t-tests indicated a significant difference only in PRESS NAAG between the two thalamus scans (p=0.002). T2 correction based on shorter T2 values showed better agreement to the dual-TE water integral ratio.

Conclusions

ISTHMUS facilitated and standardized acquisition and post-processing and reduced operator workload to eliminate potential human error.

Focusing on mitochondria in the brain: from biology to therapeutics

Mitochondria have multiple functions such as supplying energy, regulating the redox status, and producing proteins encoded by an independent genome. They are closely related to the physiology and pathology of many organs and tissues, among which the brain is particularly prominent. The brain demands 20% of the resting metabolic rate and holds highly active mitochondrial activities. Considerable research shows that mitochondria are closely related to brain function, while mitochondrial defects induce or exacerbate pathology in the brain. In this review, we provide comprehensive research advances of mitochondrial biology involved in brain functions, as well as the mitochondria-dependent cellular events in brain physiology and pathology. Furthermore, various perspectives are explored to better identify the mitochondrial roles in neurological diseases and the neurophenotypes of mitochondrial diseases. Finally, mitochondrial therapies are discussed. Mitochondrial-targeting therapeutics are showing great potentials in the treatment of brain diseases.

Abnormal mitochondrial iron metabolism damages alveolar type II epithelial cells involved in bleomycin-induced pulmonary fibrosis

Rationale: Pulmonary fibrosis is a chronic progressive lung disease with limited therapeutic options. We previously revealed that there is iron deposition in alveolar epithelial type II cell (AECII) in pulmonary fibrosis, which can be prevented by the iron chelator deferoxamine. However, iron in the cytoplasm and the mitochondria has two relatively independent roles and regulatory systems. In this study, we aimed to investigate the role of mitochondrial iron deposition in AECII injury and pulmonary fibrosis, and to find potential therapeutic strategies. Methods: BLM-treated mice, MLE-12 cells, and primary AECII were employed to establish the mouse pulmonary fibrosis model and epithelial cells injury model, respectively. Mitochondrial transplantation, siRNA and plasmid transfection, western blotting (WB), quantitative real-time polymerase chain reaction (RT-qPCR), polymerase chain reaction (PCR), immunofluorescence, immunoprecipitation (IP), MitoSOX staining, JC-1 staining, oxygen consumption rate (OCR) measurement, and Cell Counting Kit-8 (CCK8) assay were utilized to elucidate the role of mitochondrial iron deposition in cell and lung fibrosis and determine its mechanism. Results: This study showed that prominent mitochondrial iron deposition occurs within AECII in bleomycin (BLM)-induced pulmonary fibrosis mouse model and in BLM-treated MLE-12 epithelial cells. Further, the study revealed that healthy mitochondria rescue BLM-damaged AECII mitochondrial iron deposition and cell damage loss. Mitoferrin-2 (MFRN2) is the main transporter that regulates mitochondrial iron metabolism by transferring cytosolic iron into mitochondria, which is upregulated in BLM-treated MLE-12 epithelial cells. Direct overexpression of MFRN2 causes mitochondrial iron deposition and cell damage. In this study, decreased ubiquitination of the ubiquitin ligase F-box/LRR-repeat protein 5 (FBXL5) degraded iron-reactive element-binding protein 2 (IREB2) and promoted MFRN2 expression as well as mitochondrial iron deposition in damaged AECII. Activation of the prostaglandin E2 receptor EP4 subtype (EP4) receptor signaling pathway counteracted mitochondrial iron deposition by downregulating IREB2-MFRN2 signaling through upregulation of FBXL5. This intervention not only reduced mitochondrial iron content but also preserved mitochondrial function and protected against AECII damage after BLM treatment. Conclusion: Our findings highlight the unexplored roles, mechanisms, and regulatory approaches of abnormal mitochondrial iron metabolism of AECII in pulmonary fibrosis. Therefore, this study deepens the understanding of the mechanisms underlying pulmonary fibrosis and offers a promising strategy for developing effective therapeutic interventions using the EP4 receptor activator.

Role of NLRP3 in Parkinson's disease: Specific activation especially in dopaminergic neurons

Parkinson's disease (PD) is a neurodegenerative disorder with motor symptoms like bradykinesia, tremors, and balance issues. The pathology is recognized by progressively degenerative nigrostriatal dopaminergic neurons (DANs) loss. Its exact pathogenesis is unclear. Numerous studies have shown that nucleotide-binding oligomerization domain-like receptor protein 3 (NLRP3) contributes to the pathogenesis of PD. Previous studies have demonstrated that the over-activation of NLRP3 inflammasome in microglia indirectly leads to the loss of DANs, which can worsen PD. In recent years, autopsy analyses of PD patients and studies in PD models have revealed upregulation of NLRP3 expression within DANs and demonstrated that activation of NLRP3 inflammasome in neurons is sufficient to drive neuronal loss, whereas microglial activation occurs after neuronal death, and that inhibition of intraneuronal NLRP3 inflammasome prevents degeneration of DANs. In this review, we provide research evidence related to NLRP3 inflammasome in DANs in PD as well as focus on possible mechanisms of NLRP3 inflammasome activation in neurons, aiming to provide a new way of thinking about the pathogenesis and prevention of PD.

Associations of quantitative susceptibility mapping with cortical atrophy and brain connectome in Alzheimer's disease: A multi-parametric study

Aberrant susceptibility due to iron level abnormality and brain network disconnections are observed in Alzheimer's disease (AD), with disrupted iron homeostasis hypothesized to be linked to AD pathology and neuronal loss. However, whether associations exist between abnormal quantitative susceptibility mapping (QSM), brain atrophy, and altered brain connectome in AD remains unclear. Based on multi-parametric brain imaging data from 30 AD patients and 26 healthy controls enrolled at the China-Japan Friendship Hospital, we investigated the abnormality of the QSM signal and volumetric measure across 246 brain regions in AD patients. The structural and functional connectomes were constructed based on diffusion MRI tractography and functional connectivity, respectively. The network topology was quantified using graph theory analyses. We identified seven brain regions with both reduced cortical thickness and abnormal QSM (p < 0.05) in AD, including the right superior frontal gyrus, left superior temporal gyrus, right fusiform gyrus, left superior parietal lobule, right superior parietal lobule, left inferior parietal lobule, and left precuneus. Correlations between cortical thickness and network topology computed across patients in the AD group resulted in statistically significant correlations in five of these regions, with higher correlations in functional compared to structural topology. We computed the correlation between network topological metrics, QSM value and cortical thickness across regions at both individual and group-averaged levels, resulting in a measure we call spatial correlations. We found a decrease in the spatial correlation of QSM and the global efficiency of the structural network in AD patients at the individual level. These findings may provide insights into the complex relationships among QSM, brain atrophy, and brain connectome in AD.

Parkinson's disease and Parkinsonism syndromes: Evaluating iron deposition in the putamen using magnetic susceptibility MRI techniques - A systematic review and literature analysis

Magnetic resonance imaging (MRI) techniques, such as quantitative susceptibility mapping (QSM) and susceptibility-weighted imaging (SWI), can detect iron deposition in the brain. Iron accumulation in the putamen (PUT) can contribute to the pathogenesis of Parkinson's disease (PD) and atypical Parkinsonian disorders. This systematic review aimed to synthesize evidence on iron deposition in the PUT assessed by MRI susceptibility techniques in PD and Parkinsonism syndromes. The PubMed and Scopus databases were searched for relevant studies. Thirty-four studies from January 2007 to October 2023 that used QSM, SWI, or other MRI susceptibility methods to measure putaminal iron in PD, progressive supranuclear palsy (PSP), multiple system atrophy (MSA), and healthy controls (HCs) were included. Most studies have found increased putaminal iron levels in PD patients versus HCs based on higher quantitative susceptibility. Putaminal iron accumulation correlates with worse motor scores and cognitive decline in patients with PD. Evidence regarding differences in susceptibility between PD and atypical Parkinsonism is emerging, with several studies showing greater putaminal iron deposition in PSP and MSA than in PD patients. Alterations in putaminal iron levels help to distinguish these disorders from PD. Increased putaminal iron levels appear to be associated with increased disease severity and progression. Thus, magnetic susceptibility MRI techniques can detect abnormal iron accumulation in the PUT of patients with Parkinsonism. Moreover, quantifying putaminal susceptibility may serve as an MRI biomarker to monitor motor and cognitive changes in PD and aid in the differential diagnosis of Parkinsonian disorders.

SuanZaoRen decoction alleviates neuronal loss, synaptic damage and ferroptosis of AD via activating DJ-1/Nrf2 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

SuanZaoRen Decoction (SZRD), a famous herbal prescription, and has been widely proven to have positive therapeutic effects on insomnia, depression and Alzheimer's disease (AD). However, the anti-AD molecular mechanism of SZRD remains to be further investigated.

AIM OF THE STUDY

To elucidate the molecular mechanism of SZRD's improvement in AD's neuronal loss, synaptic damage and ferroptosis by regulating DJ-1/Nrf2 signaling pathway.

MATERIALS AND METHODS

LC-MS/MS was used to detect the active ingredients from SZRD. APP/PS1 mice was treated with SZRD and a ferroptosis inhibitor (Liproxstatin-1), respectively. Upon the completion of behavioral tests, Nissl staining, FJB staining, Golgi staining, immunofluorescence, immunohistochemistry, and transmission electron microscopy were preformed to evaluate the effects of SZRD on neuronal loss, synaptic damage, Aβ deposition. Iron staining, transmission electron microscopy, and iron assay kit was performed to estimate the effects of SZRD on ferroptosis. SOD kit, MDA kit, GSH kit, and GSH/GSSG kit were utilized to measure the oxidative stress levels in the hippocampus. The protein expression of TfR1, FTH1, FTL, FPN1, DJ-1, Nrf2, GPX4, SLC7A11, and ACSL4 were detected by Western blot.

RESULTS

A total of 16 active ingredients were identified from SZRD extract. SZRD SZRD significantly alleviated learning and memory impairment in APP/PS1 mice. SZRD improved the hippocampal neuronal loss and degenerated neurons in APP/PS1 mice via inhibiting the Aβ deposit. SZRD mitigated the hippocampal synaptic damage in APP/PS1 mice. SZRD inhibited iron accumulation, and alleviated the oxidative stress level in the hippocampus of APP/PS1 mice. Meanwhile, SZRD could up-regulate the protein expression level of FPN1, DJ-1, Nrf2, GPX4 and SLC7A11 in the hippocampus, and inhibit TfR1, FTH1, FTL, and ACSL4 protein expression.

CONCLUSION

SZRD alleviated neuronal loss, synaptic damage and ferroptosis in AD via activating DJ-1/Nrf2 signaling pathway.