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EJNMMI Reports Jul 2024This study aimed to establish radiomics models based on positron emission tomography (PET) images to longitudinally predict transition from mild cognitive impairment...
BACKGROUND
This study aimed to establish radiomics models based on positron emission tomography (PET) images to longitudinally predict transition from mild cognitive impairment (MCI) to Alzheimer's disease (AD).
METHODS
In our study, 278 MCI patients from the ADNI database were analyzed, where 60 transitioned to AD (pMCI) and 218 remained stable (sMCI) over 48 months. Patients were divided into a training set (n = 222) and a validation set (n = 56). We first employed voxel-based analysis of 18F-FDG PET images to identify brain regions that present significant SUV difference between pMCI and sMCI groups. Radiomic features were extracted from these regions, key features were selected, and predictive models were developed for individual and combined brain regions. The models' effectiveness was evaluated using metrics like AUC to determine the most accurate predictive model for MCI progression.
RESULTS
Voxel-based analysis revealed four brain regions implicated in the progression from MCI to AD. These include ROI1 within the Temporal lobe, ROI2 and ROI3 in the Thalamus, and ROI4 in the Limbic system. Among the predictive models developed for these individual regions, the model utilizing ROI4 demonstrated superior predictive accuracy. In the training set, the AUC for the ROI4 model was 0.803 (95% CI 0.736, 0.865), and in the validation set, it achieved an AUC of 0.733 (95% CI 0.559, 0.893). Conversely, the model based on ROI3 showed the lowest performance, with an AUC of 0.75 (95% CI 0.685, 0.809). Notably, the comprehensive model encompassing all identified regions (ROI total) outperformed the single-region models, achieving an AUC of 0.884 (95% CI 0.845, 0.921) in the training set and 0.816 (95% CI 0.705, 0.909) in the validation set, indicating significantly enhanced predictive capability for MCI progression to AD.
CONCLUSION
Our findings underscore the Limbic system as the brain region most closely associated with the progression from MCI to AD. Importantly, our study demonstrates that a PET brain radiomics model encompassing multiple brain regions (ROI total) significantly outperforms models based on single brain regions. This comprehensive approach more accurately identifies MCI patients at high risk of progressing to AD, offering valuable insights for non-invasive diagnostics and facilitating early and timely interventions in clinical settings.
PubMed: 38945980
DOI: 10.1186/s41824-024-00206-8 -
Chemical & Pharmaceutical Bulletin 2024Alzheimer's disease (AD) is the leading cause of senile dementia, and the rapid increase in the frequency of AD cases has been attributed to population aging. However,... (Review)
Review
Alzheimer's disease (AD) is the leading cause of senile dementia, and the rapid increase in the frequency of AD cases has been attributed to population aging. However, current drugs have difficulty adequately suppressing symptoms and there is still a medical need for symptomatic agents. On the other hand, it has recently become clear that epigenetic dysfunctions are deeply involved in the development of cognitive impairments. Therefore, epigenetics-related proteins have attracted much attention as drug targets for AD. Early-developed epigenetic inhibitors were inappropriate for AD treatment because of their limited potential for oral administration, blood-brain barrier penetration, high target selectivity, and sufficient dose-limiting toxicity which are essential properties for small molecule drugs targeting chronic neurodegenerative diseases such as AD. In recent years, drug discovery studies have been actively performed to overcome such problems and several novel inhibitors targeting the epigenetics-related proteins are of interest as promising AD therapeutic agents. Here, we review the small molecule inhibitors of histone deacetylase (HDAC), lysine-specific demethylase 1 (LSD1) or bromodomains and extra-terminal domain (BET) protein, that enable memory function improvement in AD model mice.
Topics: Alzheimer Disease; Humans; Animals; Epigenesis, Genetic; Histone Deacetylase Inhibitors; Histone Demethylases; Histone Deacetylases
PubMed: 38945939
DOI: 10.1248/cpb.c23-00027 -
Chemical & Pharmaceutical Bulletin 2024Alzheimer's disease (AD) is a common form of dementia. Although the causal mechanisms of AD are not fully understood, intracerebral accumulation of amyloid beta (Aβ)... (Review)
Review
Alzheimer's disease (AD) is a common form of dementia. Although the causal mechanisms of AD are not fully understood, intracerebral accumulation of amyloid beta (Aβ) and tau aggregates seems to play an important role in disease development. Therefore, numerous experimental and clinical studies targeting the Aβ and tau proteins have been performed. However, these treatments have not achieved good clinical results. Additionally, recent findings have indicated that immune abnormalities contribute to the pathogenesis of AD. Several immune- and microglia-related genes have been identified as putative causative genes for the disease. Microglia, which are resident immune cells in the central nervous system (CNS), are key players that maintain brain homeostasis by communicating with other cells, such as astrocytes and immune cells, in or around the CNS. Furthermore, dysfunction of microglia and the immune system of the CNS could lead to chronic neuroinflammation and impairment of protective neuroimmune responses, which have been associated with the pathogenesis of AD and other forms of dementia. In this review, we assemble information regarding genetic evidence, imaging and biofluid biomarkers, and the pathophysiology of AD, especially highlighting bilateral (protective or detrimental) microglial functions, thus connecting neuroimmune dysfunction and AD. We also introduce candidate drugs to target neuroimmune dysfunction in AD. Finally, we discuss future therapeutic precision medicine approaches for AD, which could be achieved by identifying and targeting signals critical for AD pathogenesis through analyses of interactions between genetic risk factors, as well as identifying and modulating disease-relevant immune cell populations.
Topics: Humans; Alzheimer Disease; Microglia; Animals; Dementia; Amyloid beta-Peptides
PubMed: 38945938
DOI: 10.1248/cpb.c23-00464 -
Chemical & Pharmaceutical Bulletin 2024Agitation and psychosis are key behavioral and psychological symptoms of Alzheimer's disease (AD). For family and caregivers of patients, such symptoms are critical... (Review)
Review
Agitation and psychosis are key behavioral and psychological symptoms of Alzheimer's disease (AD). For family and caregivers of patients, such symptoms are critical factors of distress and increased burden, but medication to treat them is limited. In most cases, drugs for other neuropsychiatric diseases have been used to manage these symptoms in an off-label manner. Due to the complex pathological background of AD and limited clinical data, obtaining proof of concept for the treatment of these symptoms is challenging. However, in 2023, the U.S. Food and Drug Administration approved brexpiprazole as the first and only drug to treat agitation in AD. Several other compounds have been evaluated in clinical situations. This review highlights recent pipelines being developed for agitation and psychosis for patients living with AD.
Topics: Alzheimer Disease; Humans; Psychotic Disorders; Psychomotor Agitation; Antipsychotic Agents
PubMed: 38945937
DOI: 10.1248/cpb.c23-00416 -
Progress in Neurobiology Jun 2024Neuromyelitis optica (NMO) arises from primary astrocytopathy induced by autoantibodies targeting the astroglial protein aquaporin 4 (AQP4), leading to severe...
Neuromyelitis optica (NMO) arises from primary astrocytopathy induced by autoantibodies targeting the astroglial protein aquaporin 4 (AQP4), leading to severe neurological sequelae such as vision loss, motor deficits, and cognitive decline. Mounting evidence has shown that dysregulated activation of complement components contributes to NMO pathogenesis. Complement C3 deficiency has been shown to protect against hippocampal neurodegeneration and cognitive decline in neurodegenerative disorders (e.g., Alzheimer's disease, AD) and autoimmune diseases (e.g., multiple sclerosis, MS). However, whether inhibiting the C3 signaling can ameliorate cognitive dysfunctions in NMO remains unclear. In this study, we found that the levels of C3a, a split product of C3, significantly correlate with cognitive impairment in our patient cohort. In response to the stimulation of AQP4 autoantibodies, astrocytes were activated to secrete complement C3, which inhibited the development of cultured neuronal dendritic arborization. NMO mouse models exhibited reduced adult hippocampal newborn neuronal dendritic and spine development, as well as impaired learning and memory functions, which could be rescued by decreasing C3 levels in astrocytes. Mechanistically, we found that C3a engaged with C3aR to impair neuronal development by dampening β-catenin signalling. Additionally, inhibition of the C3-C3aR-GSK3β/β-catenin cascade restored neuronal development and ameliorated cognitive impairments. Collectively, our results suggest a pivotal role of the activation of the C3-C3aR network in neuronal development and cognition through mediating astrocyte and adult-born neuron communication, which represents a potential therapeutic target for autoimmune-related cognitive impairment diseases.
PubMed: 38945516
DOI: 10.1016/j.pneurobio.2024.102654 -
Neurobiology of Disease Jun 2024The temporal component of episodic memory has been recognized as a sensitive behavioral marker in early stage of Alzheimer's disease (AD) patients. However, parallel...
The temporal component of episodic memory has been recognized as a sensitive behavioral marker in early stage of Alzheimer's disease (AD) patients. However, parallel studies in AD animals are currently lacking, and the underlying neural circuit mechanisms remain poorly understood. Using a novel App knock-in (APP-KI) rat model, the developmental changes of temporal order memory (TOM) and the relationship with medial prefrontal cortex and perirhinal cortex (mPFC-PRH) circuit were determined through in vivo electrophysiology and microimaging technique. We observed a deficit in TOM performance during the object temporal order memory task (OTOMT) in APP-KI rats at 6 month old, which was not evident at 3 or 4 months of age. Alongside behavioral changes, we identified a gradually extensive and aggravated regional activation and functional alterations in the mPFC and PRH during the performance of OTOMT, which occurred prior to the onset of TOM deficits. Moreover, coherence analysis showed that the functional connectivity between the mPFC and PRH could predict the extent of future behavioral performance. Further analysis revealed that the aberrant mPFC-PRH interaction mainly attributed to the progressive deterioration of synaptic transmission, information flow and network coordination from mPFC to PRH, suggesting the mPFC dysfunction maybe the key area of origin underlying the early changes of TOM. These findings identify a pivotal role of the mPFC-PRH circuit in mediating the TOM deficits in the early stage of AD, which holds promising clinical translational value and offers potential early biological markers for predicting AD memory progression.
PubMed: 38945496
DOI: 10.1016/j.nbd.2024.106584 -
Gene Jun 2024Endosomal acid base balance functions as a master orchestrator within the cell, engaging with many cellular pathways to maintain homeostasis. Mutations in the endosomal...
Endosomal acid base balance functions as a master orchestrator within the cell, engaging with many cellular pathways to maintain homeostasis. Mutations in the endosomal pH regulator Na/H exchanger NHE6 may disrupt this delicate balancing act and cause monogenic Parkinsonism. Here, gene expression studies in post-mortem substantia nigra of Parkinson's disease (PD) patients and normal controls were performed to investigate whether NHE6 represents a pathophysiological link between monogenic and sporadic PD. The substantia nigra in PD displayed down-regulation of NHE6, coincident with a loss of expression of several SNARE signalling pathway members, suggesting impaired membrane fusion and vesicle-recycling. Increased abundance of related NHE9 was also identified in the parkinsonian nigra that could reflect compensatory changes or be a consequence of neuronal dysfunction. The current model suggests the possibility that neurons expressing low levels of NHE6 are more susceptible to injury in PD, potentially directly contributing to the loss of nigral dopaminergic neurons and the genesis of the disease. These results have important implications for disease-modifying therapies as they suggest that endosomal pH correctors, including epigenetic modifiers that regulate NHE6 expression, may be beneficial for PD. Thus, aberrant endosomal acidification in the nigrostriatal pathway is a possible unifying pathomechanism in both monogenic and sporadic PD, with implications for understanding and treating this disorder. Replication of these observations in the post-mortem brains of Alzheimer's disease and frontotemporal dementia patients supports a model of conserved mechanisms underlying injury and death of neurons.
PubMed: 38945311
DOI: 10.1016/j.gene.2024.148737 -
The American Journal of the Medical... Jun 2024
PubMed: 38945271
DOI: 10.1016/j.amjms.2024.06.028 -
Journal of Asian Natural Products... Jun 2024Histone deacetylase 6 (HDAC6) was a potential target for Alzheimer's disease (AD). In this study, a series of novel oxyevodiamine-based HDAC6 inhibitors with a variety...
Histone deacetylase 6 (HDAC6) was a potential target for Alzheimer's disease (AD). In this study, a series of novel oxyevodiamine-based HDAC6 inhibitors with a variety of linker moieties were designed, synthesized and evaluated. Compound with a benzyl linker was identified as a high potent and selective HDAC6 inhibitor. It inhibited HDAC6 with an IC value of 6.2 nM and was more than 200 fold selectivity over HDAC1. It also had lower cytotoxicity and higher anti-HO activity comparing with other derivatives. Compound might be a good lead as novel HDAC6 inhibitor for the treatment of AD.
PubMed: 38945152
DOI: 10.1080/10286020.2024.2362383 -
Chemical & Pharmaceutical Bulletin 2024Lysine demethylase 5 (KDM5) proteins are involved in various neurological disorders, including Alzheimer's disease, and KDM5 inhibition is expected to be a therapeutic...
Lysine demethylase 5 (KDM5) proteins are involved in various neurological disorders, including Alzheimer's disease, and KDM5 inhibition is expected to be a therapeutic strategy for these diseases. However, the pharmacological effects of conventional KDM5 inhibitors are insufficient, as they only target the catalytic functionality of KDM5. To identify compounds that exhibit more potent pharmacological activity, we focused on proteolysis targeting chimeras (PROTACs), which degrade target proteins and thus inhibit their entire functionality. We designed and synthesized novel KDM5 PROTAC candidates based on previously identified KDM5 inhibitors. The results of cellular assays revealed that two compounds, 20b and 23b, exhibited significant neurite outgrowth-promoting activity through the degradation of KDM5A in neuroblastoma neuro 2a cells. These results suggest that KDM5 PROTACs are promising drug candidates for the treatment of neurological disorders.
Topics: Proteolysis; Humans; Neuronal Outgrowth; Structure-Activity Relationship; Enzyme Inhibitors; Cell Line, Tumor; Molecular Structure; Retinoblastoma-Binding Protein 2; Animals; Mice; Dose-Response Relationship, Drug; Proteolysis Targeting Chimera
PubMed: 38945940
DOI: 10.1248/cpb.c23-00026