Translational Neurodegeneration最新文献

Background: Parkinson disease (PD) is characterized by progressive neuronal loss within defined brain regions, accompanied by α-synuclein (αSyn)-rich inclusions, termed Lewy pathology (LP). However, it is unclear which cellular factors render certain neuronal populations vulnerable, while others stay devoid of LP throughout the course of disease.

Methods: This study aimed to identify and compare the cellular architecture of vulnerable and non-vulnerable neurons exposed to αSyn pathology by using a projection-based retro-AAV approach in combination with an in vivo α-synucleinopathy mouse model. To do so, a set of viral genetic, immunohistochemical, and optical tools was used in combination with the preformed αSyn fibril (PFF) model.

Results: αSyn pathology propagated robustly into the input connectome of the pedunculopontine nucleus (PPN). However, we observed a marked mismatch between the anatomically expected and the actual distribution of pathology. While anatomically connected neurons in the bed nucleus of the stria terminalis (BST) and the central amygdala (CEA) accumulated substantial αSyn pathology, equally strong connected neurons of the substantia nigra pars reticulata (SNr), and the dentate nucleus (DN) were devoid of pathology. Second, cellular vulnerability and resilience were consistent and reproducible features. When PFFs were injected into alternative major output projection sites of BST, CEA, SNr, and DN, we observed similar patterns of αSyn accumulation. Third, projection-specific axonal mapping revealed that the αSyn-accumulating BST and CEA neurons possessed larger axonal arbors than the more resilient neurons in SNr and DN. Correspondingly, neurons in BST and CEA exhibited higher basal mitochondrial oxidation levels, indicating an increased bioenergetic burden. Finally, the site of initial seeding significantly influenced the extent of developing brain-wide pathology, suggesting that certain brain regions may function as "super-seeders", promoting widespread propagation of pathology, while others contribute relatively little to the global LP burden.

Conclusions: αSyn pathology propagates along anatomical pathways, but cell-autonomous factors determine if a neuron exposed to misfolded αSyn will develop Lewy-like pathology or not.

The intricate cellular architecture and dynamic molecular interplay in the nervous system have long challenged mechanistic studies of neurological diseases. Conventional approaches often miss the transient, low-affinity, or spatially confined interactions that underlie neural homeostasis and pathogenesis. Proximity labeling (PL) technologies overcome this limitation by enabling in situ capture of these elusive molecular events within living systems. Through spatially restricted biotinylation, PL methods, including engineered biotin ligases (e.g., TurboID), peroxidases (e.g., APEX2), and emerging photocatalytic platforms, allow high-resolution mapping of proteomes and interactomes within defined subcellular compartments, cell types, and cell-cell interfaces. In this review, we systematically outline the principles of PL and its transformative applications in constructing molecular atlases of the nervous system. We highlight how these tools are revolutionizing our understanding of brain function by elucidating pathophysiological mechanisms in Alzheimer's disease, Parkinson's disease and other neurological disorders. Furthermore, we discuss how PL accelerates the translation of basic research into clinical practice by facilitating the discovery of mechanistic biomarkers and druggable targets. Finally, we address current challenges and future directions, including integration with multi-omics and single-cell methodologies, and conclude that PL can advance precision neurology by bridging molecular neurobiology with therapeutic innovation.

Background: Antibody-based positron emission tomography (PET) imaging holds great promise for visualizing disease-related proteins in the brain. However, its clinical utility is limited by poor antibody penetration across the blood-brain barrier (BBB) and the requirement for long-lived radionuclides due to slow antibody pharmacokinetics. Pretargeted imaging strategies, in which antibody administration and radioligand injection are separated in time, enable the use of short-lived, high-resolution PET-compatible radionuclides such as fluorine-18.

Methods: A bispecific antibody, Bapi-Fab8D3, which targets both amyloid beta (Aβ) and the transferrin receptor (TfR) for TfR-mediated transport across the BBB, was conjugated with trans-cyclooctene (TCO) to enable in vivo click chemistry. Following antibody administration to Alzheimer's disease (AD) model mice and sufficient time for accumulation at intrabrain Aβ deposits, a fluorine-18-labeled tetrazine was injected to react in vivo with the TCO handles on the antibody. PET imaging, autoradiography, ex vivo quantification, and histological analyses were performed to evaluate the specificity and distribution of the imaging signal.

Results: Bapi-Fab8D3 retained its binding affinity for both Aβ and TfR after TCO-conjugation. In brain sections, reactive TCOs were detected up to three days after antibody injection, indicating successful transcytosis across the BBB and stable target engagement. Pretargeted PET imaging after fluorine-18-labeled tetrazine injection revealed significantly higher signals in AD mice that received TCO-Bapi-Fab8D3 compared to wild-type controls or AD mice that received the unmodified antibody. The uptake pattern corresponded to Aβ plaque distribution, and quantitative analysis showed increased signal in AD-relevant brain regions including the hippocampus and thalamus.

Conclusions: This study demonstrates successful pretargeted PET imaging of brain Aβ pathology using a systemically administered bispecific antibody capable of BBB penetration and a fluorine-18-labeled tetrazine. These findings establish a generalizable strategy for high-contrast in vivo imaging of brain protein targets using pretargeted PET, with the potential to expand molecular imaging to protein targets in the brain that are currently inaccessible.

Microfluidic systems are an innovative engineering solution that is increasingly being used in a wide range of scientific fields. These systems use fluids in microchannels (1 to 300 microns) to analyze extremely small volumes of sample and reagent, allowing precise delivery and mixing while maintaining accurate results. Parkinson's disease (PD) poses significant diagnostic challenges, with early detection being critical to improved treatment outcomes. A key pathological feature of PD is the presence of Lewy bodies composed of α-synuclein (αSyn) fibrils. Recent research has shown that αSyn oligomers can be toxic and contribute to neuronal loss. Therefore, microfluidics offers a promising approach for the diagnosis of different stages of αSyn pathology. This review comprehensively analyzes the application of microfluidics in single-cell analysis and protein aggregation studies. We discuss the concept of lab-on-a-chip analysis and examine different substrates for αSyn detection, citing relevant studies and expected protein concentrations and their correlations with disease progression and severity.

Background: Neurovascular biomarkers have the potential to enhance early diagnosis of Alzheimer's disease (AD) and AD-related dementias (ADRD), as cerebrovascular alterations often precede neurodegeneration. However, their clinical application remains challenging due to insufficient specificity, heterogeneity, and technical limitations.

Methods: Here, we report that vessel- and cortical layer-specific parameters exhibit promising diagnostic sensitivity for neurovascular impairments in an AD/ADRD mouse model, apolipoprotein E (APOE) 4 knock-in (KI), compared to APOE3-KI at 12 months of age. Using two in vivo imaging modalities, 3D capillary-resolution optical Doppler tomography and laser speckle contrast imaging, we measured 36 morphological and functional vascular parameters and evaluated their diagnostic performance using a machine-learning Support Vector Machine classifier.

Results: APOE4 mice showed significant alterations including reduced venular and arterial cerebral blood flow velocities and diameters, increased vascular tortuosity, layer-dependent decreases in vascular density, and impaired cerebrovascular reactivity. Venule- and microcirculation-related parameters and dynamic vasoactivity to brain stimuli demonstrated high diagnostic accuracy (~ 90%).

Conclusion: Together, these findings provide in vivo evidence for early, cortical layer-specific neurovascular dysfunction caused by APOE4 that increases the susceptibility to dementia and highlight the potential of combining neurovascular biomarkers from optical imaging with AI-based classifier for identification of increased AD/ADRD risk.

Background: Atg9-containing vesicles are enriched in synapses and undergo cycles of exo- and endocytosis similarly to synaptic vesicles, thereby linking presynaptic autophagy to neuronal activity. Dysfunction of presynaptic autophagy is a pathophysiological mechanism in motoneuron disease (MND), which leads to impaired synaptic integrity and function. Here, we asked whether boosting neuronal activity by physical exercise modulates the cellular and motor phenotypes of Plekhg5-deficient mice, an MND model with defective presynaptic autophagy.

Methods: To characterize the vesicle accumulations in Plekhg5-deficient mice, we performed immunohistochemical staining, electron microscopy, and super-resolution imaging. Following voluntary running wheel exercise, we quantified the histopathological changes within the spinal cord and at neuromuscular junctions using an unbiased machine-learning approach. Additionally, we analyzed the motor performance of the animals by measuring their grip strength. To assess changes in the autophagic flux upon physical exercise in vivo, we utilized mRFP-GFP-LC3 expressing mice. The presence of Atg9-containing vesicle clusters in SOD1^G93A was analyzed to examine the relevance of this pathological feature in a second MND model.

Results: We found marked accumulations of Atg9-containing vesicles at presynaptic sites of Plekhg5-deficient mice, which could be cleared by four weeks of voluntary running wheel exercise in young but surprisingly not in aged Plekhg5-deficient mice. However, physical exercise in aged mice led to synaptic vesicle sorting into the Atg9-containing vesicle accumulations without their removal. In line with these findings, short-term voluntary exercise triggered motoneuron autophagy in young but not old mice. Pointing to a broader role of Atg9-containing vesicles in the pathophysiology of MND, we also found Atg9-containing vesicle accumulations in SOD1^G93A mice, a well-established ALS model. Strikingly, physical exercise in presymptomatic SOD1^G93A mice resulted in a reduction of the vesicle accumulations.

Conclusions: Our data highlight the essential role of Atg9 in presynaptic autophagy and suggest that boosting autophagy by physical exercise provides a tool to maintain presynaptic function at the early but not late stages of Plekhg5-associated MND and possibly amyotrophic lateral sclerosis.

Background: Amyotrophic lateral sclerosis (ALS) is characterised by degeneration of motor neurons, leading to muscle weakness and progressive paralysis. Currently, no treatment is available to halt or reverse the progression of the disease. Oxidative stress, mitochondrial dysfunction, accumulation of unfolded proteins and inflammation are interconnected key actors involved in ALS. A potent therapeutic strategy would be to find molecules that break this vicious circle leading to neuronal dysfunction and death. Targeting sigma-1 receptor (S1R) could meet this objective, as this chaperone protein modulates many cell survival mechanisms. So far, the impact of S1R activation in ALS has been studied using specific agonists and mostly on the SOD1 mutation that represents only 2% of patients. In the present study, the impact of two different S1R activators, the reference agonist PRE-084 and the positive modulator OZP002, was compared on two key ALS genes: TDP43 and C9orf72.

Methods: The dissociation of S1R from Binding immunoglobulin Protein (BiP) was determined using ELISA. OZP002 toxicity was compared to PRE-084 on zebrafish larvae with increasing concentrations. The efficacy of OZP002 and PRE-084 was evaluated on the locomotor escape response of zebrafish expressing mutant TDP43 or one C9orf72 toxic dipeptide. Their effects on NRF2 target gene expression were studied by qPCR. The beneficial effect was further examined on the locomotor performances of TDP43^A315T mice using rotarod and beam walking tests. We also performed analysis on motor neuron loss and glial reactivity.

Results: OZP002 is a positive modulator of S1R, that increases the dissociation of the S1R-BiP complex induced by orthosteric agonists. S1R activation by both OZP002 and PRE-084 restored the locomotor response of ALS zebrafish expressing either TDP43 or one C9orf72 toxic dipeptide. The neuroprotection was due at least in part to the NRF2 cascade stimulation but not with a direct interaction. More importantly, OZP002 and PRE-084 prevented locomotor defects and degeneration of spinal motor neurons in TDP43^A315T transgenic mice. Astroglial and microglial reactivities were also reduced by both activators.

Conclusions: We here emphasize the therapeutic value of S1R activation in mitigating ALS pathology. Additionally, we show that the positive modulators pave the way for the development of new S1R-activating compounds for ALS treatment.

Lipofuscin, a marker of aging, is the accumulation of autofluorescent granules within microglia and postmitotic cells such as neurons. Lipofuscin has traditionally been regarded as an inert byproduct of cellular degradation. However, recent findings suggest that lipofuscin may play a role in modulating age-related neurodegenerative processes, and several questions remain unanswered. For instance, why do lipofuscin granules accumulate preferentially in aged neurons and microglia? What happens to these pigments upon neuronal demise? Particularly in neurodegenerative diseases like Alzheimer's disease (AD), why does amyloid β (Aβ) deposition usually begin in late adulthood or during aging? Why do lipofuscin and amyloid plaques appear preferentially in grey matter and rarely in white matter? In this review, we argue that lipofuscin should be revisited not as a simple biomarker of aging, but as a potential modulator of neurodegenerative diseases. We synthesize emerging evidence linking lipofuscin to lysosomal dysfunction, oxidative stress, lipid peroxidation and disease onset-mechanisms critically implicated in neurodegeneration. We also explore the potential interactions of lipofuscin with Aβ and their spatial location, and summarize evidence showing that lipofuscin may influence disease progression via feedback loops affecting cellular clearance and inflammation. Finally, we propose future research directions toward better understanding of the mechanisms of lipofuscin accumulation and improved lysosomal waste clearance in aging.

Parkinson's disease (PD) is increasingly recognized as a multisystem disorder involving pathological α-synuclein (α-syn) accumulation and widespread neuroimmune dysregulation. Microglia, the resident immune cells in the central nervous system (CNS), are pivotal mediators of the bidirectional communication between the CNS and peripheral systems. In addition to sensing neuronal injury and α-syn pathology, microglia dynamically respond to peripheral immune signals, including circulating cytokines, immune cell infiltration, and microbial metabolites, through pattern recognition receptors such as Toll-like and NOD-like receptors. Furthermore, microglia regulate blood-brain barrier integrity, modulate peripheral immune cell recruitment, interact with meningeal lymphatic vessels, and contribute to the propagation of α-syn within the CNS and along the gut-brain axis. However, a comprehensive framework encompassing their diverse roles in peripheral-central immune crosstalk remains underdeveloped. This review synthesizes recent advances elucidating how microglia link the CNS to peripheral immune and metabolic signals in PD. We further highlight microglial contributions to α-syn propagation along the gut-brain axis and discuss how their functional states influence disease progression. A deeper understanding of microglial involvement in this complex neuroimmune interface may inform the development of effective and system-level therapeutic strategies for PD.

Advancements in visualization methods have brought the meningeal lymphatic system (MLS) into the spotlight. The meningeal lymphatic vessels (mLVs) play a vital role in draining cerebrospinal fluid and immune cells, acting as a central hub for immune surveillance in the brain. Age-related morphological and functional declines of mLVs suggest their involvement in the pathogenesis of neurodegenerative disorders (NDDs). In this article, we summarize key discoveries about the MLS over the past decade, highlight the neuro-immune crosstalk in the meninges, and discuss the role of mLVs in both brain homeostasis and neurodegeneration. As a critical regulator of brain function and a potential therapeutic target, the MLS offers a promising avenue for the diagnosis and treatment of NDDs, particularly Alzheimer's Disease.