Journal of Alzheimer's Disease - Volume 94, issue s1

Authors: Li, Tianqi | Pappas, Colleen | Klinedinst, Brandon | Pollpeter, Amy | Larsen, Brittany | Hoth, Nathan | Anton, Faith | Wang, Qian | Willette, Auriel A.

Article Type: Research Article

Abstract: Background: Insulin-like growth factor (IGF)-1 plays an important role in Alzheimer’s disease (AD) pathogenesis and increases disease risk. However, prior research examining IGF-1 levels and brain neural network activity is mixed. Objective: The present study investigated the relationship between IGF-1 levels and 21 neural networks, as measured by functional magnetic resonance imaging (fMRI) in 13,235 UK Biobank participants. Methods: Linear mixed models were used to regress IGF-1 against the intrinsic functional connectivity (i.e., degree of network activity) for each neural network. Interactions between IGF-1 and AD risk factors such as Apolipoprotein E4 (APOE4 ) genotype, sex, …AD family history, and age were also tested. Results: Higher IGF-1 was associated with more network activity in the right Executive Function neural network. IGF-1 interactions with APOE4 or sex implicated motor, primary/extrastriate visual, and executive function related neural networks. Neural network activity trends with increasing IGF-1 were different in different age groups. Higher IGF-1 levels relate to much more network activity in the Sensorimotor Network and Cerebellum Network in early-life participants (40–52 years old), compared with mid-life (52–59 years old) and late-life (59–70 years old) participants. Conclusion: These findings suggest that sex and APOE4 genotype may modify the relationship between IGF-1 and brain network activities related to visual, motor, and cognitive processing. Additionally, IGF-1 may have an age-dependent effect on neural network connectivity. Show more

Keywords: Alzheimer’s disease, cognitive dysfunction, functional MRI, insulin-like growth factor-1

DOI: 10.3233/JAD-220608

Citation: Journal of Alzheimer's Disease, vol. 94, no. s1, pp. S309-S318, 2023

Authors: Basha, SK Chand | Ramaiah, Mekala Janaki | Kosagisharaf, Jagannatha Rao

Article Type: Review Article

Abstract: Alzheimer’s disease (AD) is a complex neurodegenerative disorder involving heterogenous pathophysiological characteristics, which has become a challenge to therapeutics. The major pathophysiology of AD comprises amyloid-β (Aβ), tau, oxidative stress, and apoptosis. Recent studies indicate the significance of Triggering receptor expressed on myeloid cells 2 (TREM2) and its mutant variants in AD. TREM2 are the transmembrane receptors of microglial cells that performs a broad range of physiological cell processes. Phagocytosis of Aβ is one of the physiological roles of TREM2, which plays a pivotal role in AD progression. R47H, a mutant variant of TREM2, increases the risk of AD by …impairing TREM2–Aβ binding. Inconclusive evidence regarding the TREM2 signaling cascade mechanism of Aβ phagocytosis motivates the current review to propose a new hypothesis. The review systematically assesses the cross talk between TREM2 and other AD pathological domains and the influence of TREM2 on amyloid and tau seeding. Disease associated microglia (DAM), a novel state of microglia with unique transcriptional and functional signatures reported in neurodegenerative conditions, also depend on the TREM2 pathway for its differentiation. DAM is suggested to have a neuroprotective role. We hypothesize that TREM2, along with its signaling adaptors and endogenous proteins, play a key role in ameliorating Aβ clearance. We indicate that TREM2 has the potential to ameliorate the Aβ burden, though with differential clearance ability and may act as a potential therapeutic target. Show more

Keywords: Alzheimer’s disease, amyloid-β, DAP10, DAP12, disease associated microglia, microglia, neurodegeneration, PLCγ2, DAM, R47H, TREM2

DOI: 10.3233/JAD-221070

Citation: Journal of Alzheimer's Disease, vol. 94, no. s1, pp. S319-S333, 2023

Authors: Huang, Wenhao | Xia, Qing | Zheng, Feifei | Zhao, Xue | Ge, Fangliang | Xiao, Jiaying | Liu, Zijie | Shen, Yingying | Ye, Ke | Wang, Dayong | Li, Yanze

Article Type: Review Article

Abstract: The neurovascular unit (NVU) is involved in the pathological changes in Alzheimer’s disease (AD). The NVU is a structural and functional complex that maintains microenvironmental homeostasis and metabolic balance in the central nervous system. As one of the most important components of the NVU, microglia not only induce blood-brain barrier breakdown by promoting neuroinflammation, the infiltration of peripheral white blood cells and oxidative stress but also mediate neurovascular uncoupling by inducing mitochondrial dysfunction in neurons, abnormal contraction of cerebral vessels, and pericyte loss in AD. In addition, microglia-mediated dysfunction of cellular components in the NVU, such as astrocytes and pericytes, …can destroy the integrity of the NVU and lead to NVU impairment. Therefore, we review the mechanisms of microglia-mediated NVU dysfunction in AD. Furthermore, existing therapeutic advancements aimed at restoring the function of microglia and the NVU in AD are discussed. Finally, we predict the role of pericytes in microglia-mediated NVU dysfunction in AD is the hotspot in the future. Show more

Keywords: Alzheimer’s disease, blood-brain barrier, microglia, neurovascular uncoupling, neurovascular unit, pericyte

DOI: 10.3233/JAD-221064

Citation: Journal of Alzheimer's Disease, vol. 94, no. s1, pp. S335-S354, 2023

Authors: Guo, Xiaodi | Zhang, Guoxin | Peng, Qinyu | Huang, Liqin | Zhang, Zhaohui | Zhang, Zhentao

Article Type: Review Article

Abstract: Meningeal lymphatic vessels (mLVs), the functional lymphatic system present in the meninges, are the key drainage route responsible for the clearance of molecules, immune cells, and cellular debris from the cerebrospinal fluid and interstitial fluid into deep cervical lymph nodes. Aging and ApoE4, the two most important risk factors for Alzheimer’s disease (AD), induce mLV dysfunction, decrease cerebrospinal fluid influx and outflux, and exacerbate amyloid pathology and cognitive dysfunction. Dysfunction of mLVs results in the deposition of metabolic products, accelerates neuroinflammation, and promotes the release of pro-inflammatory cytokines in the brain. Thus, mLVs represent a novel therapeutic target for treating …neurodegenerative and neuroinflammatory diseases. This review aims to summarize the structure and function of mLVs and to discuss the potential effect of aging and ApoE4 on mLV dysfunction, as well as their roles in the pathogenesis of AD. Show more

Keywords: Alzheimer’s disease, amyloid-β, Apolipoprotein E4, meningeal lymphatic vessels, tau

DOI: 10.3233/JAD-221016

Citation: Journal of Alzheimer's Disease, vol. 94, no. s1, pp. S355-S366, 2023

Authors: Zhang, Ruxin | Song, Yanrong | Su, Xuefeng

Article Type: Review Article

Abstract: Alzheimer’s disease (AD) is considered to be the most common neurodegenerative disease, with clinical symptoms encompassing progressive memory loss and cognitive impairment. Necroptosis is a form of programmed necrosis that promotes cell death and neuroinflammation, which further mediates the pathogenesis of several neurodegenerative diseases, especially AD. Current evidence has strongly suggested that necroptosis is activated in AD brains, resulting in neuronal death and cognitive impairment. We searched the PubMed database, screening all articles published before September 28, 2022 related to necroptosis in the context of AD pathology. The keywords in the search included: “necroptosis”, “Alzheimer’s disease”, “signaling pathways”, “Aβ”, Aβo”, …“Tau”, “p-Tau”, “neuronal death”, “BBB damage”, “neuroinflammation”, “microglia”, “mitochondrial dysfunction”, “granulovacuolar degeneration”, “synaptic loss”, “axonal degeneration”, “Nec-1”, “Nec-1s”, “GSK872”, “NSA”, “OGA”, “RIPK1”, “RIPK3”, and “MLKL”. Results show that necroptosis has been involved in multiple pathological processes of AD, including amyloid-β aggregation, Tau accumulation, neuronal death, and blood-brain barrier damage, etc. More importantly, existing research on AD necroptosis interventions, including drug intervention and potential gene targets, as well as its current clinical development status, was discussed. Finally, the issues pertaining to necroptosis in AD were presented. Accordingly, this review may provide further insight into clinical perspectives and challenges for the future treatment of AD by targeting the necroptosis pathway. Show more

Keywords: Alzheimer’s disease, granulovacuolar degeneration, mitochondrial dysfunction, MLKL, necroptosis, neurodegeneration, neuronal death, RIPK1, RIPK3

DOI: 10.3233/JAD-220809

Citation: Journal of Alzheimer's Disease, vol. 94, no. s1, pp. S367-S386, 2023

Authors: Krishna, Geethu | Santhoshkumar, Rashmi | Sivakumar, Palanimuthu Thangaraju | Alladi, Suvarna | Mahadevan, Anita | Dahale, Ajit B. | Arshad, Faheem | Subramanian, Sarada

Article Type: Research Article

Abstract: Background: Alzheimer’s disease (AD) and frontotemporal dementia (FTD) are pathologically distinct neurodegenerative disorders with certain overlap in cognitive and behavioral symptoms. Both AD and FTD are characterized by synaptic loss and accumulation of misfolded proteins, albeit, in different regions of the brain. Objective: To investigate the synaptic and organellar markers in AD and FTD through assessment of the levels of synaptic protein, neurogranin (Ng) and organellar proteins, mitofusin-2 (MFN-2), lysosomal associated membrane protein-2 (LAMP-2), and golgin A4 from neuronal exosomes. Methods: Exosomes isolated from the plasma of healthy controls (HC), AD and FTD subjects were characterized …using transmission electron microscopy. Neurodegenerative status was assessed by measurement of neurofilament light chain (NfL) using Simoa. The pooled exosomal extracts from each group were analyzed for Ng, MFN-2, LAMP-2, and golgin A4 by western blot analysis using enhanced chemiluminescence method of detection. Results: The densitometric analysis of immunoreactive bands demonstrated a 65% reduction of Ng in AD and 53% in FTD. Mitochondrial protein MFN-2 showed a significant reduction by 32% in AD and 46% in FTD. Lysosomal LAMP-2 and Golgi complex associated golgin A4 were considerably increased in both AD and FTD. Conclusion: Changes in Ng may reflect the ongoing synaptic degeneration that are linked to cognitive disturbances in AD and FTD. Importantly, the rate of synaptic degeneration was more pronounced in AD. Changes to a similar extent in both the dementia groups in organellar proteins indicates shared mechanisms of protein accumulation/degradation common to both AD and FTD. Show more

Keywords: Alzheimer’s disease, exosomes, frontotemporal dementia, golgin A4, immunoblotting, LAMP-2, MFN-2, neurogranin

DOI: 10.3233/JAD-220829

Citation: Journal of Alzheimer's Disease, vol. 94, no. s1, pp. S387-S397, 2023

Authors: Naren, Padmashri | Cholkar, Anjali | Kamble, Suchita | Khan, Sabiya Samim | Srivastava, Saurabh | Madan, Jitender | Mehra, Neelesh | Tiwari, Vinod | Singh, Shashi Bala | Khatri, Dharmendra Kumar

Article Type: Review Article

Abstract: Parkinson’s disease (PD) is the second most common neurodegenerative illness majorly affecting the population between the ages of 55 to 65 years. Progressive dopaminergic neuronal loss and the collective assemblage of misfolded alpha-synuclein in the substantia nigra, remain notable neuro-pathological hallmarks of the disease. Multitudes of mechanistic pathways have been proposed in attempts to unravel the pathogenesis of PD but still, it remains elusive. The convergence of PD pathology is found in organelle dysfunction where mitochondria remain a major contributor. Mitochondrial processes like bioenergetics, mitochondrial dynamics, and mitophagy are under strict regulation by the mitochondrial genome and nuclear genome. These …processes aggravate neurodegenerative activities upon alteration through neuroinflammation, oxidative damage, apoptosis, and proteostatic stress. Therefore, the mitochondria have grabbed a central position in the patho-mechanistic exploration of neurodegenerative diseases like PD. The management of PD remains a challenge to physicians to date, due to the variable therapeutic response of patients and the limitation of conventional chemical agents which only offer symptomatic relief with minimal to no disease-modifying effect. This review describes the patho-mechanistic pathways involved in PD not only limited to protein dyshomeostasis and oxidative stress, but explicit attention has been drawn to exploring mechanisms like organelle dysfunction, primarily mitochondria and mitochondrial genome influence, while delineating the newer exploratory targets such as GBA1, GLP, LRRK2, and miRNAs and therapeutic agents targeting them. Show more

Keywords: Autophagy, mitochondrial dysfunction, mitogenome, neuroinflammation, Parkinson’s disease, oxidative stress

DOI: 10.3233/JAD-220682

Citation: Journal of Alzheimer's Disease, vol. 94, no. s1, pp. S399-S428, 2023

Authors: Wong, Genper Chi-Ngai | Chow, Kim Hei-Man

Article Type: Review Article

Abstract: Chronological aging is by far the strongest risk factor for age-related dementia and Alzheimer’s disease. Senescent cells accumulated in the aging and Alzheimer’s disease brains are now recognized as the keys to describing such an association. Cellular senescence is a classic phenomenon characterized by stable cell arrest, which is thought to be applicable only to dividing cells. Emerging evidence indicates that fully differentiated post-mitotic neurons are also capable of becoming senescent, with roles in contributing to both brain aging and disease pathogenesis. The key question that arises is the identity of the upstream triggers and the molecular mechanisms that underly …such changes. Here, we highlight the potential role of persistent DNA damage response as the major driver of senescent phenotypes and discuss the current evidence and molecular mechanisms that connect DNA repair infidelity, cell cycle re-entry and terminal fate decision in committing neuronal cell senescence. Show more

Keywords: Alzheimer’s disease, brain aging, cell cycle re-entry, neuronal cell senescence, persistent DNA damage response

DOI: 10.3233/JAD-220203

Citation: Journal of Alzheimer's Disease, vol. 94, no. s1, pp. S429-S451, 2023

Authors: Chhimpa, Neeraj | Singh, Neha | Puri, Nikkita | Kayath, Hanuman Prasad

Article Type: Review Article

Abstract: Citrate synthase is a key mitochondrial enzyme that utilizes acetyl-CoA and oxaloacetate to form citrate in the mitochondrial membrane, which participates in energy production in the TCA cycle and linked to the electron transport chain. Citrate transports through a citrate malate pump and synthesizes acetyl-CoA and acetylcholine (ACh) in neuronal cytoplasm. In a mature brain, acetyl-CoA is mainly utilized for ACh synthesis and is responsible for memory and cognition. Studies have shown low citrate synthase in different regions of brain in Alzheimer’s disease (AD) patients, which reduces mitochondrial citrate, cellular bioenergetics, neurocytoplasmic citrate, acetyl-CoA, and ACh synthesis. Reduced citrate mediated …low energy favors amyloid-β (Aβ) aggregation. Citrate inhibits Aβ25–35 and Aβ1–40 aggregation in vitro . Hence, citrate can be a better therapeutic option for AD by improving cellular energy and ACh synthesis, and inhibiting Aβ aggregation, which prevents tau hyperphosphorylation and glycogen synthase kinase-3 beta. Therefore, we need clinical studies if citrate reverses Aβ deposition by balancing mitochondrial energy pathway and neurocytoplasmic ACh production. Furthermore, in AD’s silent phase pathophysiology, when neuronal cells are highly active, they shift ATP utilization from oxidative phosphorylation to glycolysis and prevent excessive generation of hydrogen peroxide and reactive oxygen species (oxidative stress) as neuroprotective action, which upregulates glucose transporter-3 (GLUT3) and pyruvate dehydrogenase kinase-3 (PDK3). PDK3 inhibits pyruvate dehydrogenase, which decreases mitochondrial-acetyl-CoA, citrate, and cellular bioenergetics, and decreases neurocytoplasmic citrate, acetyl-CoA, and ACh formation, thus initiating AD pathophysiology. Therefore, GLUT3 and PDK3 can be biomarkers for silent phase of AD. Show more

Keywords: Acetyl-CoA, acetylcholine, Alzheimer’s disease, amyloid-beta, APOE ɛ4, cellular bioenergetics, citrate, citrate synthase, GLUT3

DOI: 10.3233/JAD-220514

Citation: Journal of Alzheimer's Disease, vol. 94, no. s1, pp. S453-S472, 2023