Neurogranin in Alzheimer's disease and ageing: A human post-mortem study

HDAC4 Inhibits NMDA Receptor-mediated Stimulation of Neurogranin Expression

The coordination of neuronal wiring and activity within the central nervous system (CNS) is crucial for cognitive function, particularly in the context of aging and neurological disorders. Neurogranin (Ng), an abundant forebrain protein, modulates calmodulin (CaM) activity and deeply influences synaptic plasticity and neuronal processing. This study investigates the regulatory mechanisms of Ng expression, a critical but underexplored area for combating cognitive impairment. Utilizing both in vitro and in vivo hippocampal models, we show that Ng expression arises during late developmental stages, coinciding with the processes of synaptic maturation and neuronal circuit consolidation. We observed that Ng expression increases in neuronal networks with heightened synaptic activity and identified GluN2B-containing N-methyl-D-aspartate (NMDA) receptors as key drivers of this expression. Additionally, we discovered that nuclear-localized HDAC4 inhibits Ng expression, establishing a regulatory axis that is counteracted by NMDA receptor stimulation. Analysis of the Ng gene promoter activity revealed regulatory elements between the - 2.4 and - 0.85 Kbp region, including a binding site for RE1-Silencing Transcription factor (REST), which may mediate HDAC4's repressive effect on Ng expression. Further analysis of the promoter sequence revealed conserved binding sites for the myocyte enhancer factor-2 (MEF2) transcription factor, a target of HDAC4-mediated transcription regulation. Our findings elucidate the interplay between synaptic activity, NMDAR function, and transcriptional regulation in controlling Ng expression, offering insights into synaptic plasticity mechanisms and potential therapeutic strategies to prevent cognitive dysfunction.

The Cooperation of Neurogranin with Calmodulin Promotes the Treatment of Aging-Related Diseases via Regular Exercise

Research has demonstrated that engaging in regular exercise has the potential to enhance cognitive function, promote neuroplasticity, and mitigate the likelihood of experiencing cognitive decline. The underlying mechanisms responsible for these effects are intricate and encompass various pathways, including the interaction between neurogranin and calmodulin. The activation of calcium signaling pathways is a significant mechanism through which regular exercise facilitates the treatment of age-related diseases. The activation of neurogranin and calmodulin induced by exercise can provide protection against neurodegeneration by promoting neuronal survival, mitigating oxidative stress, and improving mitochondrial function through the regulation of calcium homeostasis and energy metabolism. In addition, there is evidence suggesting that engaging in regular exercise can lead to an upregulation of neurotrophic factors, specifically brain-derived neurotrophic factor (BDNF). These factors are crucial for the survival of neurons, the plasticity of synapses, and overall cognitive function. Researchers have discovered the involvement of neurogranin in the regulation of BDNF signaling, underscoring its significance in exercise-induced neuroprotection and cognitive enhancement. The current work offers valuable insights into how neurogranin/calmodulin cooperation, facilitated by regular exercise, promotes the treatment of aging-related diseases. The results suggest that regular exercise could enhance memory, learning, synaptic plasticity, and resilience to neurological damage; promote recovery after brain injury; and treat aging-related disorders such as Alzheimer's disease.

The Potential Role of Neurogranin in Alzheimer's Disease

Alzheimer's disease (AD) is the most common form of dementia and is characterized by the excessive deposition of amyloid-β (Aβ) plaques and the formation of neurofibrillary tangles. Numerous new studies also indicate that synaptic damage and loss play crucial roles in AD and form the basis of cognitive impairment. In recent years, synaptic-related proteins have emerged as important biomarkers for the early diagnosis of AD. Among these proteins, neurogranin (Ng), a postsynaptic protein widely present in the dendritic spines of the associative cortex in the brain, plays a significant role in memory, learning, synaptic plasticity, and long-term potentiation (LTP). This review aims to reveal the link between Ng and AD, as well as the potential for the diagnosis of AD, the prediction of the development of the disease, and the identification of a therapeutic target for AD.

Biomarkers of synaptic degeneration in Alzheimer's disease

Synapse has been considered a critical neuronal structure in the procession of Alzheimer's disease (AD), attacked by two pathological molecule aggregates (amyloid-β and phosphorylated tau) in the brain, disturbing synaptic homeostasis before disease manifestation and subsequently causing synaptic degeneration. Recently, evidence has emerged indicating that soluble oligomeric amyloid-β (AβO) and tau exert direct toxicity on synapses, causing synaptic damage. Synaptic degeneration is closely linked to cognitive decline in AD, even in the asymptomatic stages of AD. Therefore, the identification of novel, specific, and sensitive biomarkers involved in synaptic degeneration holds significant promise for early diagnosis of AD, reducing synaptic degeneration and loss, and controlling the progression of AD. Currently, a range of biomarkers in cerebrospinal fluid (CSF), such as synaptosome-associated protein 25 (SNAP-25), synaptotagmin-1, growth-associated protein-43 (GAP-43), and neurogranin (Ng), along with functional brain imaging techniques, can detect variations in synaptic density, offering high sensitivity and specificity for AD diagnosis. However, these methods face challenges, including invasiveness, high cost, and limited accessibility. In contrast, biomarkers found in blood or urine provide a minimally invasive, cost-effective, and more accessible alternative to traditional diagnostic methods. Notably, neuron-derived exosomes in blood, which contain synaptic proteins, show variations in concentration that can serve as indicators of synaptic injury, providing an additional, less invasive approach to AD diagnosis and monitoring.

Early-stage Alzheimer's disease profiling in blood achieved by multiplexing aptamer-SERS biosensors

Neurological disorders are the second leading cause of death globally, with Alzheimer's disease (AD) emerging as a significant contributor, responsible for 276 million cases in disability-adjusted life years. Conventional diagnostic methods are often invasive, costly, and place a considerable strain on global healthcare systems. In this study, we presented an innovative and efficient strategy for AD assessment through blood profiling using a multiwell glass chip integrated with aptamer-based surface-enhanced Raman scattering (SERS) biosensors. High-affinity aptamers were selected using capillary electrophoresis-based systematic evolution of ligands by exponential enrichment (CE-SELEX). A mouse brain injury model was employed to systematically investigate biomarkers indicative of physiological, vascular, and cellular damage, such as neurogranin (Nrgn), angiopoietin-2 (Angio-2), PRDX3, lactate dehydrogenase (L-LDH), and τ-441, which were quantified at atto-molar levels in blood samples. Additionally, with the aid of CT-scan imaging, an aptamer-SERS assay was developed to evaluate the dynamic regulation of AD biomarkers. The aptamer-SERS biosensor system was also applied to human samples, demonstrating its capability to multiplex AD biomarkers and establish a time-dependent correlation between percentage biomarker regulation and disease progression. The innovative design, fabrication of aptamer-SERS nanoprobes, and the bio-sensing outcomes illustrate the strong potential of this approach for selective, sensitive, and quantitative early-stage AD diagnosis in clinical applications.

Exploring peripheral fluid biomarkers for early detection of Alzheimer's disease in Down syndrome: A literature review

People with Down Syndrome (DS) are at high risk of developing Alzheimer's disease dementia (AD) and cerebral amyloid angiopathy, which is a critical factor contributing to dementia in sporadic AD. Predicting and monitoring the decline and onset of dementia is a diagnostic challenge and of essence in daily care and support for people with DS. In this literature scoping review, we first summarize the different blood-based biomarkers for AD in DS. Next, we describe urine-based biomarkers for AD in DS and finally, we explore various blood-based biomarkers in the general AD population. Apart from the classic amyloid beta and Tau biomarkers, we also discuss more out-of-the-box biomarkers such as neurofilament light chain, Dual-specificity tyrosine-regulated kinase 1A, and monoaminergic biomarkers. These potential biomarkers could be a valuable addition to the established panel of fluid biomarkers.

A multifactorial lens on risk factors promoting the progression of Alzheimer's disease

The prevalence of Alzheimer's disease (AD) among adults has continued to increase over the last two decades, which has sparked a significant increase in research that focuses on the topic of "brain health." While AD is partially determined by a genetic predisposition, there are still numerous pathophysiological factors that require further research. This research requirement stems from the acknowledgment that AD is a multifactorial disease that to date, cannot be prevented. Therefore, addressing and understanding the potential AD risk factors is necessary to increase the quality of life of an aging population. To raise awareness of critical pathways that impact AD progression, this review manuscript describes AD etiologies, structural impairments, and biomolecular changes that can significantly increase the risk of AD. Among them, a special highlight is given to inflammasomes, which have been shown to bolster neuroinflammation. Alike, the role of brain-derived neurotrophic factor, an essential neuropeptide that promotes the preservation of cognition is presented. In addition, the functional role of neurovascular units to regulate brain health is highlighted and contrasted to inflammatory conditions, such as cellular senescence, vascular damage, and increased visceral adiposity, who all increase the risk of neuroinflammation. Altogether, a multifactorial interventional approach is warranted to reduce the risk of AD.

Cumulative Socioeconomic Status Risk is Associated With Greater Increase in Serum Neurofilament Light Chain Levels Among Middle-Aged Black Adults

BACKGROUND

This study examined the longitudinal relationship between cumulative socioeconomic status (SES) risk and serum neurofilament light chain (NfL) levels to better understand the association between social factors and a biomarker of neurodegeneration.

METHODS

We used data from the Family and Community Health Study, collecting psychosocial and blood data at 2 waves (2008) and (2019) from 254 Black Americans (43 males and 211 females). Blood samples were analyzed at each wave for serum NfL concentrations. Regression analysis and mixed-effect modeling examined relationships between cumulative SES risk and serum NfL, controlling for covariates and assessing time effects.

RESULTS

Utilizing 11-year longitudinal data, serum NfL levels increased with age. Higher cumulative SES risk at baseline correlated with elevated serum NfL at the 11-year follow-up and predicted a greater increase in NfL levels. Clinically, NfL is a sensitive biomarker for axonal injury and neurodegeneration, commonly used to detect early and preclinical stages of conditions such as Alzheimer's disease, multiple sclerosis, and other neurodegenerative disorders.

CONCLUSIONS

Our results suggest that exposure to cumulative SES risk among Black adults may contribute to elevated levels of NfL, indicating potential early neurodegeneration. Given the established role of NfL in detecting neurodegenerative processes, these findings underscore the importance of interventions that bolster social safety nets and social connectedness to enhance brain health and mitigate neurodegenerative risks.

Cerebrospinal Fluid Neurofilaments Light-Chain Differentiate Patients Affected by Alzheimer's Disease with Different Rate of Progression (RoP): A Preliminary Study

Alzheimer's disease (AD) is the most common neurodegenerative disorder and a leading cause of dementia. One major challenge for clinicians is accurately assessing the rate of disease progression (RoP) early in the diagnostic process, which is crucial for patient management and clinical trial stratification. This study evaluated the role of cerebrospinal fluid biomarkers-Aβ42, t-Tau, pTau, Neurogranin (Ng), and Neurofilament light-chain (NF-L)-in predicting RoP at the time of AD diagnosis. We included 56 AD patients and monitored cognitive impairment using MMSE scores at diagnosis and during six-month follow-up visits. RoP scores were calculated based on these assessments. Our correlation analyses revealed significant associations between RoP and pTau, Aβ42/Ng ratio, and NF-L levels. When patients were stratified by median RoP values into low-to-moderate (L-M: <2) and upper-moderate (U-M: >2) groups, those in the U-M group had notably higher CSF NF-L levels compared to the L-M group. Logistic regression analysis further demonstrated that elevated CSF NF-L levels were predictive of a faster RoP. These findings highlight the potential of CSF NF-L as a prognostic biomarker for rapid disease progression in AD. By identifying patients at risk for accelerated cognitive decline, CSF NF-L could significantly enhance early intervention strategies and improve patient management in clinical settings.

Age-associated changes in innate and adaptive immunity: role of the gut microbiota

Aging is generally regarded as an irreversible process, and its intricate relationship with the immune system has garnered significant attention due to its profound implications for the health and well-being of the aging population. As people age, a multitude of alterations occur within the immune system, affecting both innate and adaptive immunity. In the realm of innate immunity, aging brings about changes in the number and function of various immune cells, including neutrophils, monocytes, and macrophages. Additionally, certain immune pathways, like the cGAS-STING, become activated. These alterations can potentially result in telomere damage, the disruption of cytokine signaling, and impaired recognition of pathogens. The adaptive immune system, too, undergoes a myriad of changes as age advances. These include shifts in the number, frequency, subtype, and function of T cells and B cells. Furthermore, the human gut microbiota undergoes dynamic changes as a part of the aging process. Notably, the interplay between immune changes and gut microbiota highlights the gut's role in modulating immune responses and maintaining immune homeostasis. The gut microbiota of centenarians exhibits characteristics akin to those found in young individuals, setting it apart from the microbiota observed in typical elderly individuals. This review delves into the current understanding of how aging impacts the immune system and suggests potential strategies for reversing aging through interventions in immune factors.

Inflammasome-Inhibiting Nanoligomers Are Neuroprotective against Space-Induced Pathology in Healthy and Diseased Three-Dimensional Human Motor and Prefrontal Cortex Brain Organoids

The microgravity and space environment has been linked to deficits in neuromuscular and cognitive capabilities, hypothesized to occur due to accelerated aging and neurodegeneration in space. While the specific mechanisms are still being investigated, spaceflight-associated neuropathology is an important health risk to astronauts and space tourists and is being actively investigated for the development of appropriate countermeasures. However, such space-induced neuropathology offers an opportunity for accelerated screening of therapeutic targets and lead molecules for treating neurodegenerative diseases. Here, we show a proof-of-concept high-throughput target screening (on Earth), target validation, and mitigation of microgravity-induced neuropathology using our Nanoligomer platform, onboard the 43-day SpaceX CRS-29 mission to the International Space Station. First, comparing 3D healthy and diseased prefrontal cortex (PFC, for cognition) and motor neuron (MN, for neuromuscular function) organoids, we assessed space-induced pathology using biomarkers relevant to Alzheimer's disease (AD), frontotemporal dementia (FTD), and amyotrophic lateral sclerosis (ALS). Both healthy and diseased PFC and MN organoids showed significantly enhanced neurodegeneration in space, as measured through relevant disease biomarkers, when compared to their respective Earth controls. Second, we tested the top two lead molecules, NI112 that targeted NF-κB and NI113 that targeted IL-6. We observed that these Nanoligomers significantly mitigate the AD, FTD, and ALS relevant biomarkers like amyloid beta-42 (Aβ42), phosphorylated tau (pTau), Kallikrein (KLK-6), Tar DNA-binding protein 43 (TDP-43), and others. Moreover, the 43-day Nanoligomer treatment of these brain organoids did not appear to cause any observable toxicity or safety issues in the target organoid tissue, suggesting good tolerability for these molecules in the brain at physiologically relevant doses. Together, these results show significant potential for both the development and translation of NI112 and NI113 molecules as potential neuroprotective countermeasures for safer space travel and demonstrate the usefulness of the space environment for rapid, high-throughput screening of targets and lead molecules for clinical translation. We assert that the use of microgravity in drug development and screening may ultimately benefit millions of patients suffering from debilitating neurodegenerative diseases on Earth.

Glial reactivity is linked to synaptic dysfunction across the aging and Alzheimer's disease spectrum

Previous studies have shown that glial and neuronal changes may trigger synaptic dysfunction in Alzheimer's disease(AD). However, the link between glial and neuronal markers and synaptic abnormalities in the living brain is poorly understood. Here, we investigated the association between biomarkers of astrocyte and microglial reactivity and synaptic dysfunction in 478 individuals across the aging and AD spectrum from two cohorts with available CSF measures of amyloid-β(Aβ), phosphorylated tau(pTau181), astrocyte reactivity(GFAP), microglial activation(sTREM2), and synaptic biomarkers(GAP43 and neurogranin). Elevated CSF GFAP levels were linked to presynaptic and postsynaptic dysfunction, regardless of cognitive status or Aβ presence. CSF sTREM2 levels were associated with presynaptic biomarkers in cognitively unimpaired and impaired Aβ + individuals and postsynaptic biomarkers in cognitively impaired Aβ + individuals. Notably, CSF pTau181 levels mediated all associations between GFAP or sTREM2 levels and synaptic dysfunction biomarkers. These results suggest that neuronal-related synaptic biomarkers could be used in clinical trials targeting glial reactivity in AD.

Exercise to Counteract Alzheimer's Disease: What Do Fluid Biomarkers Say?

Neurodegenerative diseases (NDs) represent an unsolved problem to date with an ever-increasing population incidence. Particularly, Alzheimer's disease (AD) is the most widespread ND characterized by an accumulation of amyloid aggregates of beta-amyloid (Aβ) and Tau proteins that lead to neuronal death and subsequent cognitive decline. Although neuroimaging techniques are needed to diagnose AD, the investigation of biomarkers within body fluids could provide important information on neurodegeneration. Indeed, as there is no definitive solution for AD, the monitoring of these biomarkers is of strategic importance as they are useful for both diagnosing AD and assessing the progression of the neurodegenerative state. In this context, exercise is known to be an effective non-pharmacological management strategy for AD that can counteract cognitive decline and neurodegeneration. However, investigation of the concentration of fluid biomarkers in AD patients undergoing exercise protocols has led to unclear and often conflicting results, suggesting the need to clarify the role of exercise in modulating fluid biomarkers in AD. Therefore, this critical literature review aims to gather evidence on the main fluid biomarkers of AD and the modulatory effects of exercise to clarify the efficacy and usefulness of this non-pharmacological strategy in counteracting neurodegeneration in AD.

TauP301L disengages from the proteosome core complex and neurogranin coincident with enhanced neuronal network excitability

Tauopathies are characterised by the pathological accumulation of misfolded tau. The emerging view is that toxic tau species drive synaptic dysfunction and potentially tau propagation before measurable neurodegeneration is evident, but the underlying molecular events are not well defined. Human non-mutated 0N4R tau (tauWT) and P301L mutant 0N4R tau (tauP301L) were expressed in mouse primary cortical neurons using adeno-associated viruses to monitor early molecular changes and synaptic function before the onset of neuronal loss. In this model tauP301L was differentially phosphorylated relative to tauwt with a notable increase in phosphorylation at ser262. Affinity purification - mass spectrometry combined with tandem mass tagging was used to quantitatively compare the tauWT and tauP301L interactomes. This revealed an enrichment of tauP301L with ribosomal proteins but a decreased interaction with the proteasome core complex and reduced tauP301L degradation. Differences in the interaction of tauP301L with members of a key synaptic calcium-calmodulin signalling pathway were also identified, most notably, increased association with CaMKII but reduced association with calcineurin and the candidate AD biomarker neurogranin. Decreased association of neurogranin to tauP301L corresponded with the appearance of enhanced levels of extracellular neurogranin suggestive of potential release or leakage from synapses. Finally, analysis of neuronal network activity using micro-electrode arrays showed that overexpression of tauP301L promoted basal hyperexcitability coincident with these changes in the tau interactome and implicating tau in specific early alterations in synaptic function.

Potential Application of MicroRNAs and Some Other Molecular Biomarkers in Alzheimer's Disease

Alzheimer's disease (AD) is the world's most common neurodegenerative disease, expected to affect up to one-third of the elderly population in the near future. Among the major challenges in combating AD are the inability to reverse the damage caused by the disease, expensive diagnostic tools, and the lack of specific markers for the early detection of AD. This paper highlights promising research directions for molecular markers in AD diagnosis, including the diagnostic potential of microRNAs. The latest molecular methods for diagnosing AD are discussed, with particular emphasis on diagnostic techniques prior to the appearance of full AD symptoms and markers detectable in human body fluids. A collection of recent studies demonstrates the promising potential of molecular methods in AD diagnosis, using miRNAs as biomarkers. Up- or downregulation in neurodegenerative diseases may not only provide a new diagnostic tool but also serve as a marker for differentiating neurodegenerative diseases. However, further research in this direction is needed.

Neuroinflammation driven by human immunodeficiency virus-1 (HIV-1) directs the expression of long noncoding RNA RP11-677M14.2 resulting in dysregulation of neurogranin in vivo and in vitro

Neuroinflammation and synaptodendritic damage represent the pathological hallmarks of HIV-1 associated cognitive disorders (HAND). The post-synaptic protein neurogranin (Nrgn) is significantly reduced in the frontal cortex of postmortem brains from people with HIV (PWH) and it is associated with inflammatory factors released by infected microglia/macrophages. However, the mechanism involved in synaptic loss have yet to be elucidated. In this study, we characterized a newly identified long non-coding RNA (lncRNA) transcript (RP11-677M14.2), which is antisense to the NRGN locus and is highly expressed in the frontal cortex of HIV-1 individuals. Further analysis indicates an inverse correlation between the expression of RP11-677M14.2 RNA and Nrgn mRNA. Additionally, the Nrgn-lncRNA axis is dysregulated in neurons exposed to HIV-1 infected microglia conditioned medium enriched with IL-1β. Moreover, in vitro overexpression of this lncRNA impacts Nrgn expression at both mRNA and protein levels. Finally, we modeled the Nrgn-lncRNA dysregulation within an HIV-1-induced inflammatory environment using brain organoids, thereby corroborating our in vivo and in vitro findings. Together, our study implicates a plausible role for lncRNA RP11-677M14.2 in modulating Nrgn expression that might serve as the mechanistic link between Nrgn loss and cognitive dysfunction in HAND, thus shedding new light on the mechanisms underlying synaptodendritic damage.

Molecular Biomarkers of Neurodegenerative Disorders: A Practical Guide to Their Appropriate Use and Interpretation in Clinical Practice

Neurodegenerative disorders (NDs) represent a group of different diseases characterized by the progressive degeneration and death of the nervous system's cells. The diagnosis is challenging, especially in the early stages, due to no specific clinical signs and symptoms. In this context, laboratory medicine could support clinicians in detecting and differentiating NDs. Indeed, biomarkers could indicate the pathological mechanisms underpinning NDs. The ideal biofluid for detecting the biomarkers of NDs is cerebrospinal fluid (CSF), which has limitations, hampering its widespread use in clinical practice. However, intensive efforts are underway to introduce high-sensitivity analytical methods to detect ND biomarkers in alternative nonivasive biofluid, such as blood or saliva. This study presents an overview of the ND molecular biomarkers currently used in clinical practice. For some diseases, such as Alzheimer's disease or multiple sclerosis, biomarkers are well established and recommended by guidelines. However, for most NDs, intensive research is ongoing to identify reliable and specific biomarkers, and no consensus has yet been achieved.

Biofluid biomarkers for Alzheimer's disease

Alzheimer's disease (AD) is a multifactorial neurodegenerative disease, with a complex pathogenesis and an irreversible course. Therefore, the early diagnosis of AD is particularly important for the intervention, prevention, and treatment of the disease. Based on the different pathophysiological mechanisms of AD, the research progress of biofluid biomarkers are classified and reviewed. In the end, the challenges and perspectives of future research are proposed.

Modulation of hippocampal protein expression by a brain penetrant biologic TNF-α inhibitor in the 3xTg Alzheimer's disease mice

BACKGROUND

Biologic TNF-α inhibitors (bTNFIs) can block cerebral TNF-α in Alzheimer's disease (AD) if these macromolecules can cross the blood-brain barrier (BBB). Thus, a model bTNFI, the extracellular domain of type II TNF-α receptor (TNFR), which can bind to and sequester TNF-α, was fused with a mouse transferrin receptor antibody (TfRMAb) to enable brain delivery via BBB TfR-mediated transcytosis. Previously, we found TfRMAb-TNFR to be protective in a mouse model of amyloidosis (APP/PS1) and tauopathy (PS19), and herein we investigated its effects in mice that combine both amyloidosis and tauopathy (3xTg-AD).

METHODS

Eight-month-old female 3xTg-AD mice were injected intraperitoneally with saline (n = 11) or TfRMAb-TNFR (3 mg/kg; n = 11) three days per week for 12 weeks. Age-matched wild-type (WT) mice (n = 9) were treated similarly with saline. Brains were processed for immunostaining and high-resolution multiplex NanoString GeoMx spatial proteomics.

RESULTS

We observed regional differences in proteins relevant to Aβ, tau, and neuroinflammation in the hippocampus of 3xTg-AD mice compared with WT mice. From 64 target proteins studied using spatial proteomics, a comparison of the Aβ-plaque bearing vs. plaque-free regions in the 3xTg-AD mice yielded 39 differentially expressed proteins (DEP) largely related to neuroinflammation (39% of DEP) and Aβ and tau pathology combined (31% of DEP). Hippocampal spatial proteomics revealed that the majority of the proteins modulated by TfRMAb-TNFR in the 3xTg-AD mice were relevant to microglial function (⁓ 33%). TfRMAb-TNFR significantly reduced mature Aβ plaques and increased Aβ-associated microglia around larger Aβ deposits in the 3xTg-AD mice. Further, TfRMAb-TNFR increased mature Aβ plaque-associated microglial TREM2 in 3xTg-AD mice.

CONCLUSION

Overall, despite the low visual Aβ load in the 11-month-old female 3xTg-AD mice, our results highlight region-specific AD-relevant DEP in the hippocampus of these mice. Chronic TfRMAb-TNFR dosing modulated several DEP involved in AD pathology and showed a largely microglia-centric mechanism of action in the 3xTg-AD mice.

Alzheimer's disease, aging, and cannabidiol treatment: a promising path to promote brain health and delay aging

Alzheimer's disease (AD) is the most common neurodegenerative disease characterized by progressive memory loss, neurodegeneration, and cognitive decline. Aging is one of the risk factors for AD. Although the mechanisms underlying aging and the incidence rate of AD are unclear, aging and AD share some hallmarks, such as oxidative stress and chronic inflammation. Cannabidiol (CBD), the major non-psychoactive phytocannabinoid extracted from Cannabis sativa, has recently emerged as a potential candidate for delaying aging and a valuable therapeutic tool for the treatment of aging-related neurodegenerative diseases due to its antioxidant and anti-inflammation properties. This article reviews the relevant literature on AD, CBD treatment for AD, cellular senescence, aging, and CBD treatment for aging in recent years. By analyzing these published data, we attempt to explore the complex correlation between cellular senescence, aging, and Alzheimer's disease, clarify the positive feedback effect between the senescence of neurocytes and Alzheimer's disease, and summarize the role and possible molecular mechanisms of CBD in preventing aging and treating AD. These data may provide new ideas on how to effectively prevent and delay aging, and develop effective treatment strategies for age-related diseases such as Alzheimer's disease.

Neuroinflammation driven by Human Immunodeficiency Virus-1 (HIV-1) directs the expression of long noncoding RNA RP11-677M14.2 resulting in dysregulation of Neurogranin in vivo and in vitro

Neuroinflammation and synaptodendritic damage represent the pathological hallmarks of HIV-1 associated cognitive disorders (HAND). The post-synaptic protein neurogranin (Nrgn) is significantly reduced in the frontal cortex of postmortem brains from people with HIV (PWH) and it is associated with inflammatory factors released by infected microglia/macrophages. However, the mechanism involved in synaptic loss have yet to be elucidated. In this study, we characterized a newly identified long non-coding RNA (lncRNA) transcript (RP11-677M14.2), which is antisense to the NRGN locus and is highly expressed in the frontal cortex of HIV-1 individuals. Further analysis indicates an inverse correlation between the expression of RP11-677M14.2 RNA and Nrgn mRNA. Additionally, the Nrgn-lncRNA axis is dysregulated in neurons exposed to HIV-1 infected microglia conditioned medium enriched with IL-1b. Moreover, in vitro overexpression of this lncRNA impact Nrgn expression at both mRNA and protein levels. Finally, we modeled the Nrgn-lncRNA dysregulation within an HIV-1-induced neuroinflammatory environment using brain organoids, thereby corroborating our in vivo and in vitro findings. Together, our study implicates a plausible role for lncRNA RP11-677M14.2 in modulating Nrgn expression that might serve as the mechanistic link between Nrgn loss and cognitive dysfunction in HAND, thus shedding new light on the mechanisms underlying synaptodendritic damage.

Biomarkers in Alzheimer's Disease: Are Olfactory Neuronal Precursors Useful for Antemortem Biomarker Research?

Alzheimer's disease (AD), as the main cause of dementia, affects millions of people around the world, whose diagnosis is based mainly on clinical criteria. Unfortunately, the diagnosis is obtained very late, when the neurodegenerative damage is significant for most patients. Therefore, the exhaustive study of biomarkers is indispensable for diagnostic, prognostic, and even follow-up support. AD is a multifactorial disease, and knowing its underlying pathological mechanisms is crucial to propose new and valuable biomarkers. In this review, we summarize some of the main biomarkers described in AD, which have been evaluated mainly by imaging studies in cerebrospinal fluid and blood samples. Furthermore, we describe and propose neuronal precursors derived from the olfactory neuroepithelium as a potential resource to evaluate some of the widely known biomarkers of AD and to gear toward searching for new biomarkers. These neuronal lineage cells, which can be obtained directly from patients through a non-invasive and outpatient procedure, display several characteristics that validate them as a surrogate model to study the central nervous system, allowing the analysis of AD pathophysiological processes. Moreover, the ease of obtaining and harvesting endows them as an accessible and powerful resource to evaluate biomarkers in clinical practice.

Association of region-specific hippocampal reduction of neurogranin with inflammasome proteins in post mortem brains of Alzheimer's disease

INTRODUCTION

Neurogranin (Ng) is considered a biomarker for synaptic dysfunction in Alzheimer's disease (AD). In contrast, the inflammasome complex has been shown to exacerbate AD pathology.

METHODS

We investigated the protein expression, morphological differences of Ng, and correlated Ng to hyperphosphorylated tau in the post mortem brains of 17 AD cases and 17 age- and sex-matched controls. In addition, we correlated the Ng expression with two different epitopes of apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC).

RESULTS

We show a reduction of Ng immunopositive neurons and morphological differences in AD compared to controls. Ng immunostaining was negatively correlated with neurofibrillary tangles, humanized anti-ASC (IC100) positive neurons and anti-ASC positive microglia, in AD.

DISCUSSION

The finding of a negative correlation between Ng and ASC speck protein expression in post mortem brains of AD suggests that the activation of inflammasome/ASC speck pathway may play an important role in synaptic degeneration in AD.

Highlights

We show the role that neurogranin plays on post-synaptic signaling in specific hippocampal regions.We demonstrate that there could be clinical implications of using neurogranin as a biomarker for dementia.We describe the loss of plasticity and neuronal scaffolding proteins in the present of AD pathology.We show the response of neuroinflammation when tau proteins phosphorylate in hippocampal neurons.We show that there is a potential therapeutic target for the inflammasome, and future studies may show that IC100, a humanized monoclonal antibody directed against ASC, may slow the progression of neurodegeneration.

Particulate matter exposure and neurodegenerative diseases: A comprehensive update on toxicity and mechanisms

Exposure to particulate matter (PM) has been associated with a range of health impacts, including neurological abnormalities that affect neurodevelopment, neuroplasticity, and behavior. Recently, there has been growing interest in investigating the possible relationship between PM exposure and the onset and progression of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease, and multiple sclerosis. However, the precise mechanism by which PM affects neurodegeneration is still unclear, even though several epidemiological and animal model studies have provided mechanistic insights. This article presents a review of the current research on the neurotoxicity of PM and its impact on neurodegenerative diseases. This review summarizes findings from epidemiological and animal model studies collected through searches in Google Scholar, PubMed, Web of Science, and Scopus. This review paper also discusses the reported effects of PM exposure on the central nervous system and highlights research gaps and future directions. The information presented in this review may inform public health policies aimed at reducing PM exposure and may contribute to the development of new treatments for neurodegenerative diseases. Further mechanistic and therapeutic research will be needed to fully understand the relationship between PM exposure and neurodegenerative diseases.