Safety and efficacy of sargramostim (GM-CSF) in the treatment of Alzheimer's disease

Neuron loss in the brain starts in childhood, increases exponentially with age and is halted by GM-CSF treatment in Alzheimer's disease

Aging increases the risk of neurodegeneration, cognitive decline, and Alzheimer's disease (AD). Currently no means exist to measure neuronal cell death during life or to prevent it. Here we show that cross-sectional measures of human plasma proteins released from dying/damaged neurons (ubiquitin C-terminal hydrolase-L1/UCH-L1 and neurofilament light/NfL) become exponentially higher from age 2-85; UCH-L1 rises faster in females. Glial fibrillary acidic protein (GFAP) concentrations, indicating astrogliosis/inflammation, increase exponentially after age 40. Treatment with human granulocyte-macrophage colony-stimulating factor (GM-CSF/sargramostim) halted neuronal cell death, as evidenced by reduced plasma UCH-L1 concentrations, in AD participants to levels equivalent to those of five-year-old healthy controls. The ability of GM-CSF treatment to reduce neuronal apoptosis was confirmed in a rat model of AD. These findings suggest that the exponential increase in neurodegeneration with age, accelerated by neuroinflammation, may underlie the contribution of aging to cognitive decline and AD and can be halted by GM-CSF/sargramostim treatment.

Single-Cell RNA Sequencing Reveals Immunomodulatory Effects of Stem Cell Factor and Granulocyte Colony-Stimulating Factor Treatment in the Brains of Aged APP/PS1 Mice

Alzheimer's disease (AD) leads to progressive neurodegeneration and dementia. AD primarily affects older adults with neuropathological changes including amyloid-beta (Aβ) deposition, neuroinflammation, and neurodegeneration. We have previously demonstrated that systemic treatment with combined stem cell factor (SCF) and granulocyte colony-stimulating factor (G-CSF) (SCF+G-CSF) reduces the Aβ load, increases Aβ uptake by activated microglia and macrophages, reduces neuroinflammation, and restores dendrites and synapses in the brains of aged APPswe/PS1dE9 (APP/PS1) mice. However, the mechanisms underlying SCF+G-CSF-enhanced brain repair in aged APP/PS1 mice remain unclear. This study used a transcriptomic approach to identify the potential mechanisms by which SCF+G-CSF treatment modulates microglia and peripheral myeloid cells to mitigate AD pathology in the aged brain. After injections of SCF+G-CSF for 5 consecutive days, single-cell RNA sequencing was performed on CD11b+ cells isolated from the brains of 28-month-old APP/PS1 mice. The vast majority of cell clusters aligned with transcriptional profiles of microglia in various activation states. However, SCF+G-CSF treatment dramatically increased a cell population showing upregulation of marker genes related to peripheral myeloid cells. Flow cytometry data also revealed an SCF+G-CSF-induced increase of cerebral CD45high/CD11b+ active phagocytes. SCF+G-CSF treatment robustly increased the transcription of genes implicated in immune cell activation, including gene sets that regulate inflammatory processes and cell migration. The expression of S100a8 and S100a9 was robustly enhanced following SCF+G-CSF treatment in all CD11b+ cell clusters. Moreover, the topmost genes differentially expressed with SCF+G-CSF treatment were largely upregulated in S100a8/9-positive cells, suggesting a well-conserved transcriptional profile related to SCF+G-CSF treatment in resident and peripherally derived CD11b+ immune cells. This S100a8/9-associated transcriptional profile contained notable genes related to pro-inflammatory and anti-inflammatory responses, neuroprotection, and Aβ plaque inhibition or clearance. Altogether, this study reveals the immunomodulatory effects of SCF+G-CSF treatment in the aged brain with AD pathology, which will guide future studies to further uncover the therapeutic mechanisms.

Novel Therapeutic Strategies in Alzheimer's Disease: Pitfalls and Challenges of Anti-Amyloid Therapies and Beyond

Alzheimer's disease (AD) causes a significant challenge to global healthcare systems, with limited effective treatments available. This review examines the landscape of novel therapeutic strategies for AD, focusing on the shortcomings of traditional therapies against amyloid-beta (Aβ) and exploring emerging alternatives. Despite decades of research emphasizing the role of Aβ accumulation in AD pathogenesis, clinical trials targeting Aβ have obtained disappointing results, highlighting the complexity of AD pathophysiology and the need for investigating other therapeutic approaches. In this manuscript, we first discuss the challenges associated with anti-Aβ therapies, including limited efficacy and potential adverse effects, underscoring the necessity of exploring alternative mechanisms and targets. Thereafter, we review promising non-Aβ-based strategies, such as tau-targeted therapies, neuroinflammation modulation, and gene and stem cell therapy. These approaches offer new avenues for AD treatment by addressing additional pathological hallmarks and downstream effects beyond Aβ deposition.

Specific Binding of Alzheimer's Aβ Peptides to Extracellular Vesicles

Alzheimer's disease (AD) is the fifth leading cause of death among adults aged 65 and older, yet the onset and progression of the disease is poorly understood. What is known is that the presence of amyloid, particularly polymerized Aβ42, defines when people are on the AD continuum. Interestingly, as AD progresses, less Aβ42 is detectable in the plasma, a phenomenon thought to result from Aβ becoming more aggregated in the brain and less Aβ42 and Aβ40 being transported from the brain to the plasma via the CSF. We propose that extracellular vesicles (EVs) play a role in this transport. EVs are found in bodily fluids such as blood, urine, and cerebrospinal fluid and carry diverse "cargos" of bioactive molecules (e.g., proteins, nucleic acids, lipids, metabolites) that dynamically reflect changes in the cells from which they are secreted. While Aβ42 and Aβ40 have been reported to be present in EVs, it is not known whether this interaction is specific for these peptides and thus whether amyloid-carrying EVs play a role in AD and/or serve as brain-specific biomarkers of the AD process. To determine if there is a specific interaction between Aβ and EVs, we used isothermal titration calorimetry (ITC) and discovered that Aβ42 and Aβ40 bind to EVs in a manner that is sequence specific, saturable, and endothermic. In addition, Aβ incubation with EVs overnight yielded larger amounts of bound Aβ peptide that was fibrillar in structure. These findings point to a specific amyloid-EV interaction, a potential role for EVs in the transport of amyloid from the brain to the blood, and a role for this amyloid pool in the AD process.

A Trisomy 21-linked Hematopoietic Gene Variant in Microglia Confers Resilience in Human iPSC Models of Alzheimer's Disease

While challenging, identifying individuals displaying resilience to Alzheimer's disease (AD) and understanding the underlying mechanism holds great promise for the development of new therapeutic interventions to effectively treat AD. Down syndrome (DS), or trisomy 21, is the most common genetic cause of AD. Interestingly, some people with DS, despite developing AD neuropathology, show resilience to cognitive decline. Furthermore, DS individuals are at an increased risk of myeloid leukemia due to somatic mutations in hematopoietic cells. Recent studies indicate that somatic mutations in hematopoietic cells may lead to resilience to neurodegeneration. Microglia, derived from hematopoietic lineages, play a central role in AD etiology. We therefore hypothesize that microglia carrying the somatic mutations associated with DS myeloid leukemia may impart resilience to AD. Using CRISPR-Cas9 gene editing, we introduce a trisomy 21-linked hotspot CSF2RB A455D mutation into human pluripotent stem cell (hPSC) lines derived from both DS and healthy individuals. Employing hPSC-based in vitro microglia culture and in vivo human microglia chimeric mouse brain models, we show that in response to pathological tau, the CSF2RB A455D mutation suppresses microglial type-1 interferon signaling, independent of trisomy 21 genetic background. This mutation reduces neuroinflammation and enhances phagocytic and autophagic functions, thereby ameliorating senescent and dystrophic phenotypes in human microglia. Moreover, the CSF2RB A455D mutation promotes the development of a unique microglia subcluster with tissue repair properties. Importantly, human microglia carrying CSF2RB A455D provide protection to neuronal function, such as neurogenesis and synaptic plasticity in chimeric mouse brains where human microglia largely repopulate the hippocampus. When co-transplanted into the same mouse brains, human microglia with CSF2RB A455D mutation phagocytize and replace human microglia carrying the wildtype CSF2RB gene following pathological tau treatment. Our findings suggest that hPSC-derived CSF2RB A455D microglia could be employed to develop effective microglial replacement therapy for AD and other age-related neurodegenerative diseases, even without the need to deplete endogenous diseased microglia prior to cell transplantation.

Emerging Alzheimer's disease therapeutics: promising insights from lipid metabolism and microglia-focused interventions

More than 55 million people suffer from dementia, with this number projected to double every 20 years. In the United States, 1 in 3 aged individuals dies from Alzheimer's disease (AD) or another type of dementia and AD kills more individuals than breast cancer and prostate cancer combined. AD is a complex and multifactorial disease involving amyloid plaque and neurofibrillary tangle formation, glial cell dysfunction, and lipid droplet accumulation (among other pathologies), ultimately leading to neurodegeneration and neuronal death. Unfortunately, the current FDA-approved therapeutics do not reverse nor halt AD. While recently approved amyloid-targeting antibodies can slow AD progression to improve outcomes for some patients, they are associated with adverse side effects, may have a narrow therapeutic window, and are expensive. In this review, we evaluate current and emerging AD therapeutics in preclinical and clinical development and provide insight into emerging strategies that target brain lipid metabolism and microglial function - an approach that may synergistically target multiple mechanisms that drive AD neuropathogenesis. Overall, we evaluate whether these disease-modifying emerging therapeutics hold promise as interventions that may be able to reverse or halt AD progression.

Overlapping Neuroimmune Mechanisms and Therapeutic Targets in Neurodegenerative Disorders

Many potential immune therapeutic targets are similarly affected in adult-onset neurodegenerative diseases, such as Alzheimer's (AD) disease, Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and frontotemporal dementia (FTD), as well as in a seemingly distinct Niemann-Pick type C disease with primarily juvenile onset. This strongly argues for an overlap in pathogenic mechanisms. The commonly researched immune targets include various immune cell subsets, such as microglia, peripheral macrophages, and regulatory T cells (Tregs); the complement system; and other soluble factors. In this review, we compare these neurodegenerative diseases from a clinical point of view and highlight common pathways and mechanisms of protein aggregation, neurodegeneration, and/or neuroinflammation that could potentially lead to shared treatment strategies for overlapping immune dysfunctions in these diseases. These approaches include but are not limited to immunisation, complement cascade blockade, microbiome regulation, inhibition of signal transduction, Treg boosting, and stem cell transplantation.

IL-12 sensing in neurons induces neuroprotective CNS tissue adaptation and attenuates neuroinflammation in mice

Interleukin-12 (IL-12) is a potent driver of type 1 immunity. Paradoxically, in autoimmune conditions, including of the CNS, IL-12 reduces inflammation. The underlying mechanism behind these opposing properties and the involved cellular players remain elusive. Here we map IL-12 receptor (IL-12R) expression to NK and T cells as well as neurons and oligodendrocytes. Conditionally ablating the IL-12R across these cell types in adult mice and assessing their susceptibility to experimental autoimmune encephalomyelitis revealed that the neuroprotective role of IL-12 is mediated by neuroectoderm-derived cells, specifically neurons, and not immune cells. In human brain tissue from donors with multiple sclerosis, we observe an IL-12R distribution comparable to mice, suggesting similar mechanisms in mice and humans. Combining flow cytometry, bulk and single-nucleus RNA sequencing, we reveal an IL-12-induced neuroprotective tissue adaption preventing early neurodegeneration and sustaining trophic factor release during neuroinflammation, thereby maintaining CNS integrity in mice.

Alzheimer's Disease: Novel Targets and Investigational Drugs for Disease Modification

Novel agents addressing non-amyloid, non-tau targets in Alzheimer's Disease (AD) comprise 70% of the AD drug development pipeline of agents currently in clinical trials. Most of the target processes identified in the Common Alzheimer's Disease Research Ontology (CADRO) are represented by novel agents in trials. Inflammation and synaptic plasticity/neuroprotection are the CADRO categories with the largest number of novel candidate therapies. Within these categories, there are few overlapping targets among the test agents. Additional categories being evaluated include apolipoprotein E [Formula: see text] 4 (APOE4) effects, lipids and lipoprotein receptors, neurogenesis, oxidative stress, bioenergetics and metabolism, vascular factors, cell death, growth factors and hormones, circadian rhythm, and epigenetic regulators. We highlight current drugs being tested within these categories and their mechanisms. Trials will be informative regarding which targets can be modulated to produce a slowing of clinical decline. Possible therapeutic combinations of agents may be suggested by trial outcomes. Biomarkers are evolving in concert with new targets and novel agents, and biomarker outcomes offer a means of supporting disease modification by the putative treatment. Identification of novel targets and development of corresponding therapeutics offer an important means of advancing new treatments for AD.

Analysis of shared ceRNA networks and related-hub genes in rats with primary and secondary photoreceptor degeneration

Introduction

Photoreceptor degenerative diseases are characterized by the progressive death of photoreceptor cells, resulting in irreversible visual impairment. However, the role of competing endogenous RNA (ceRNA) in photoreceptor degeneration is unclear. We aimed to explore the shared ceRNA regulation network and potential molecular mechanisms between primary and secondary photoreceptor degenerations.

Methods

We established animal models for both types of photoreceptor degenerations and conducted retina RNA sequencing to identify shared differentially expressed long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and messenger RNAs (mRNAs). Using ceRNA regulatory principles, we constructed a shared ceRNA network and performed function enrichment and protein-protein interaction (PPI) analyses to identify hub genes and key pathways. Immune cell infiltration and drug-gene interaction analyses were conducted, and hub gene expression was validated by quantitative real-time polymerase chain reaction (qRT-PCR).

Results

We identified 37 shared differentially expressed lncRNAs, 34 miRNAs, and 247 mRNAs and constructed a ceRNA network consisting of 3 lncRNAs, 5 miRNAs, and 109 mRNAs. Furthermore, we examined 109 common differentially expressed genes (DEGs) through functional annotation, PPI analysis, and regulatory network analysis. We discovered that these diseases shared the complement and coagulation cascades pathway. Eight hub genes were identified and enriched in the immune system process. Immune infiltration analysis revealed increased T cells and decreased B cells in both photoreceptor degenerations. The expression of hub genes was closely associated with the quantities of immune cell types. Additionally, we identified 7 immune therapeutical drugs that target the hub genes.

Discussion

Our findings provide new insights and directions for understanding the common mechanisms underlying the development of photoreceptor degeneration. The hub genes and related ceRNA networks we identified may offer new perspectives for elucidating the mechanisms and hold promise for the development of innovative treatment strategies.

Plasma neurofilament light chain concentrations are elevated in youth-onset type 2 diabetes and associated with neuropathy

BACKGROUND AND AIMS

The lack of easily measurable biomarkers remains a challenge in executing clinical trials for diabetic neuropathy (DN). Plasma Neurofilament light chain (NFL) concentration is a promising biomarker in immune-mediated neuropathies. Longitudinal studies evaluating NFL in DN have not been performed.

METHODS

A nested case-control study was performed on participants with youth-onset type 2 diabetes enrolled in the prospective Treatment Options for Type 2 Diabetes in Adolescents and Youth (TODAY) study. Plasma NFL concentrations were measured at 4-year intervals from 2008 to 2020 in 50 participants who developed DN and 50 participants with type 2 diabetes who did not develop DN.

RESULTS

NFL concentrations were similar in the DN and no DN groups at the first assessment. Concentrations were higher in DN participants at all subsequent assessment periods (all p < .01). NFL concentrations increased over time in both groups, with higher degrees of change in DN participants (interaction p = .045). A doubling of the NFL value at Assessment 2 in those without DN increased the odds of ultimate DN outcome by an estimated ratio of 2.86 (95% CI: [1.30, 6.33], p = .0046). At the final study visit, positive Spearman correlations (controlled for age, sex, diabetes duration, and BMI) were observed between NFL and HbA1c (0.48, p < .0001), total cholesterol (0.25, p = .018), and low-density lipoprotein (LDL (0.30, p = .0037)). Negative correlations were observed with measures of heart rate variability (-0.42 to -0.46, p = <.0001).

INTERPRETATION

The findings that NFL concentrations are elevated in individuals with youth-onset type 2 diabetes, and increase more rapidly in those who develop DN, suggest that NFL could be a valuable biomarker for DN.

Alzheimer's disease and neuroinflammation: will new drugs in clinical trials pave the way to a multi-target therapy?

Despite extensive research, no disease-modifying therapeutic option, able to prevent, cure or halt the progression of Alzheimer's disease [AD], is currently available. AD, a devastating neurodegenerative pathology leading to dementia and death, is characterized by two pathological hallmarks, the extracellular deposits of amyloid beta (Aβ) and the intraneuronal deposits of neurofibrillary tangles (NFTs) consisting of altered hyperphosphorylated tau protein. Both have been widely studied and pharmacologically targeted for many years, without significant therapeutic results. In 2022, positive data on two monoclonal antibodies targeting Aβ, donanemab and lecanemab, followed by the 2023 FDA accelerated approval of lecanemab and the publication of the final results of the phase III Clarity AD study, have strengthened the hypothesis of a causal role of Aβ in the pathogenesis of AD. However, the magnitude of the clinical effect elicited by the two drugs is limited, suggesting that additional pathological mechanisms may contribute to the disease. Cumulative studies have shown inflammation as one of the main contributors to the pathogenesis of AD, leading to the recognition of a specific role of neuroinflammation synergic with the Aβ and NFTs cascades. The present review provides an overview of the investigational drugs targeting neuroinflammation that are currently in clinical trials. Moreover, their mechanisms of action, their positioning in the pathological cascade of events that occur in the brain throughout AD disease and their potential benefit/limitation in the therapeutic strategy in AD are discussed and highlighted as well. In addition, the latest patent requests for inflammation-targeting therapeutics to be developed in AD will also be discussed.

An open-label multiyear study of sargramostim-treated Parkinson's disease patients examining drug safety, tolerability, and immune biomarkers from limited case numbers

BACKGROUND

The clinical utility and safety of sargramostim has previously been reported in cancer, acute radiation syndrome, autoimmune disease, inflammatory conditions, and Alzheimer's disease. The safety, tolerability, and mechanisms of action in Parkinson's disease (PD) during extended use has not been evaluated.

METHODS

As a primary goal, safety and tolerability was assessed in five PD patients treated with sargramostim (Leukine®, granulocyte-macrophage colony-stimulating factor) for 33 months. Secondary goals included numbers of CD4+ T cells and monocytes and motor functions. Hematologic, metabolic, immune, and neurological evaluations were assessed during a 5-day on, 2-day off therapeutic regimen given at 3 μg/kg. After 2 years, drug use was discontinued for 3 months. This was then followed by an additional 6 months of treatment.

RESULTS

Sargramostim-associated adverse events included injection-site reactions, elevated total white cell counts, and bone pain. On drug, blood analyses and metabolic panels revealed no untoward side effects linked to long-term treatment. Unified Parkinson's Disease Rating Scale scores remained stable throughout the study while regulatory T cell number and function were increased. In the initial 6 months of treatment, transcriptomic and proteomic monocyte tests demonstrated autophagy and sirtuin signaling. This finding paralleled anti-inflammatory and antioxidant activities within both the adaptive and innate immune profile arms.

CONCLUSIONS

Taken together, the data affirmed long-term safety as well as immune and anti-inflammatory responses reflecting clinical stability in PD under the sargramostim treatment. Confirmation in larger patient populations is planned in a future phase II evaluation.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT03790670, Date of Registration: 01/02/2019, URL: https://clinicaltrials.gov/ct2/show/NCT03790670?cond=leukine+parkinson%27s&draw=2&rank=2 .

Treatment with Granulocyte-Macrophage Colony-Stimulating Factor Reduces Viral Titers in the Brains of West Nile Virus-Infected Mice and Improves Survival

West Nile virus (WNV) is the leading cause of epidemic arboviral encephalitis in the United States. As there are currently no proven antiviral therapies or licensed human vaccines, understanding the neuropathogenesis of WNV is critical for rational therapeutic design. In WNV-infected mice, the depletion of microglia leads to enhanced viral replication, increased central nervous system (CNS) tissue injury, and increased mortality, suggesting that microglia play a critical role in protection against WNV neuroinvasive disease. To determine if augmenting microglial activation would provide a potential therapeutic strategy, we administered granulocyte-macrophage colony-stimulating factor (GM-CSF) to WNV-infected mice. Recombinant human GM-CSF (rHuGMCSF) (sargramostim [Leukine]) is an FDA-approved drug used to increase white blood cells following leukopenia-inducing chemotherapy or bone marrow transplantation. Daily treatment of both uninfected and WNV-infected mice with subcutaneous injections of GM-CSF resulted in microglial proliferation and activation as indicated by the enhanced expression of the microglia activation marker ionized calcium binding adaptor molecule 1 (Iba1) and several microglia-associated inflammatory cytokines, including CCL2 (C-C motif chemokine ligand 2), interleukin 6 (IL-6), and IL-10. In addition, more microglia adopted an activated morphology as demonstrated by increased sizes and more pronounced processes. GM-CSF-induced microglial activation in WNV-infected mice was associated with reduced viral titers and apoptotic activity (caspase 3) in the brains of WNV-infected mice and significantly increased survival. WNV-infected ex vivo brain slice cultures (BSCs) treated with GM-CSF also showed reduced viral titers and caspase 3 apoptotic cell death, indicating that GM-CSF specifically targets the CNS and that its actions are not dependent on peripheral immune activity. Our studies suggest that stimulation of microglial activation may be a viable therapeutic approach for the treatment of WNV neuroinvasive disease. IMPORTANCE Although rare, WNV encephalitis poses a devastating health concern, with few treatment options and frequent long-term neurological sequelae. Currently, there are no human vaccines or specific antivirals against WNV infections, so further research into potential new therapeutic agents is critical. This study presents a novel treatment option for WNV infections using GM-CSF and lays the foundation for further studies into the use of GM-CSF as a treatment for WNV encephalitis as well as a potential treatment for other viral infections.

Fountain of youth—Targeting autophagy in aging

As our society ages inexorably, geroscience and research focusing on healthy aging is becoming increasingly urgent. Macroautophagy (referred to as autophagy), a highly conserved process of cellular clearance and rejuvenation has attracted much attention due to its universal role in organismal life and death. Growing evidence points to autophagy process as being one of the key players in the determination of lifespan and health. Autophagy inducing interventions show significant improvement in organismal lifespan demonstrated in several experimental models. In line with this, preclinical models of age-related neurodegenerative diseases demonstrate pathology modulating effect of autophagy induction, implicating its potential to treat such disorders. In humans this specific process seems to be more complex. Recent clinical trials of drugs targeting autophagy point out some beneficial effects for clinical use, although with limited effectiveness, while others fail to show any significant improvement. We propose that using more human-relevant preclinical models for testing drug efficacy would significantly improve clinical trial outcomes. Lastly, the review discusses the available cellular reprogramming techniques used to model neuronal autophagy and neurodegeneration while exploring the existing evidence of autophagy’s role in aging and pathogenesis in human-derived in vitro models such as embryonic stem cells (ESCs), induced pluripotent stem cell derived neurons (iPSC-neurons) or induced neurons (iNs).

Data-driven approach to integrating genomic and behavioral preclinical traumatic brain injury research

Understanding recovery from TBI is complex, involving multiple systems and modalities. The current study applied modern data science tools to manage this complexity and harmonize large-scale data to understand relationships between gene expression and behavioral outcomes in a preclinical model of chronic TBI (cTBI). Data collected by the Moody Project for Translational TBI Research included rats with no injury (naïve animals with similar amounts of anesthetic exposure to TBI and sham-injured animals), sham injury, or lateral fluid percussion TBI, followed by recovery periods up to 12 months. Behavioral measures included locomotor coordination (beam balance neuroscore) and memory and cognition assessments (Morris water maze: MWM) at multiple timepoints. Gene arrays were performed using hippocampal and cortical samples to probe 45,610 genes. To reduce the high dimensionality of molecular and behavioral domains and uncover gene-behavior associations, we performed non-linear principal components analyses (NL-PCA), which de-noised the data. Genomic NL-PCA unveiled three interpretable eigengene components (PC2, PC3, and PC4). Ingenuity pathway analysis (IPA) identified the PCs as an integrated stress response (PC2; EIF2-mTOR, corticotropin signaling, etc.), inflammatory factor translation (PC3; PI3K-p70S6K signaling), and neurite growth inhibition (PC4; Rho pathways). Behavioral PCA revealed three principal components reflecting the contribution of MWM overall speed and distance, neuroscore/beam walk, and MWM platform measures. Integrating the genomic and behavioral domains, we then performed a 'meta-PCA' on individual PC scores for each rat from genomic and behavioral PCAs. This meta-PCA uncovered three unique multimodal PCs, characterized by robust associations between inflammatory/stress response and neuroscore/beam walk performance (meta-PC1), stress response and MWM performance (meta-PC2), and stress response and neuroscore/beam walk performance (meta-PC3). Multivariate analysis of variance (MANOVA) on genomic-behavioral meta-PC scores tested separately on cortex and hippocampal samples revealed the main effects of TBI and recovery time. These findings are a proof of concept for the integration of disparate data domains for translational knowledge discovery, harnessing the full syndromic space of TBI.

Recombinant GM-CSF for diseases of GM-CSF insufficiency: Correcting dysfunctional mononuclear phagocyte disorders

Introduction

Endogenous granulocyte-macrophage colony-stimulating factor (GM-CSF), identified by its ability to support differentiation of hematopoietic cells into several types of myeloid cells, is now known to support maturation and maintain the metabolic capacity of mononuclear phagocytes including monocytes, macrophages, and dendritic cells. These cells sense and attack potential pathogens, present antigens to adaptive immune cells, and recruit other immune cells. Recombinant human (rhu) GM-CSF (e.g., sargramostim [glycosylated, yeast-derived rhu GM-CSF]) has immune modulating properties and can restore the normal function of mononuclear phagocytes rendered dysfunctional by deficient or insufficient endogenous GM-CSF.

Methods

We reviewed the emerging biologic and cellular effects of GM-CSF. Experts in clinical disease areas caused by deficient or insufficient endogenous GM-CSF examined the role of GM-CSF in mononuclear phagocyte disorders including autoimmune pulmonary alveolar proteinosis (aPAP), diverse infections (including COVID-19), wound healing, and anti-cancer immune checkpoint inhibitor therapy.

Results

We discuss emerging data for GM-CSF biology including the positive effects on mitochondrial function and cell metabolism, augmentation of phagocytosis and efferocytosis, and immune cell modulation. We further address how giving exogenous rhu GM-CSF may control or treat mononuclear phagocyte dysfunction disorders caused or exacerbated by GM-CSF deficiency or insufficiency. We discuss how rhu GM-CSF may augment the anti-cancer effects of immune checkpoint inhibitor immunotherapy as well as ameliorate immune-related adverse events.

Discussion

We identify research gaps, opportunities, and the concept that rhu GM-CSF, by supporting and restoring the metabolic capacity and function of mononuclear phagocytes, can have significant therapeutic effects. rhu GM-CSF (e.g., sargramostim) might ameliorate multiple diseases of GM-CSF deficiency or insufficiency and address a high unmet medical need.

Therapeutic anti-amyloid β antibodies cause neuronal disturbances

INTRODUCTION

Recent published clinical trial safety data showed that 41% of Alzheimer patients experienced amyloid-related imaging abnormalities (ARIA), marks of microhemorrhages and edema in the brain, following administration of Biogen's Aduhelm/aducanumab (amino acids 3-7 of the Aβ peptide). Similarly, Janssen/Pfizer's Bapineuzumab (amino acids 1-5 of the Aβ peptide) and Roche's Gantenerumab (amino acids 2-11/18-27 of the Aβ peptide) also displayed ARIA in clinical trials, including microhemorrhage and focal areas of inflammation or vasogenic edema, respectively. The molecular mechanisms underlying ARIA caused by therapeutic anti-Aβ antibodies remain largely unknown, however, recent reports demonstrated that therapeutic anti-prion antibodies activate neuronal allergenic proteomes following cross-linking cellular prion protein.

METHODS

Here, we report that treatment of human induced pluripotent stem cells- derived neurons (HSCN) from a non-demented donor, co-cultured with human primary microglia with anti-Aβ1-6, or anti-Aβ17-23 antibodies activate a significant number of allergenic-related proteins as assessed by mass spectrometry.

RESULTS

Interestingly, a large proportion of the identified proteins included cytokines such as interleukin (IL)-4, IL-12, and IL-13 suggesting a type-1 hypersensitivity response. Following flow cytometry analysis, several proinflammatory cytokines were significantly elevated following anti-Aβ1-6, or anti-Aβ17-23 antibody treatment.

DISCUSSION

These results justify further and more robust investigation of the molecular mechanisms of ARIA during immunotherapy study trials of AD.

HIGHLIGHTS

Allergenic-related proteins are often linked with Alzheimer's disease (AD). We investigated the effects of amyloid beta (Aβ) immunotherapy on stem cell derived neurons and primary neuronal cells co-cultured with microglia. Anti-Aβ antibody treatment of neurons or neurons co-cultured with microglia led to activation of a substantial number of allergenic-related genes. These allergenic-related genes are associated with endothelial dysfunction possibly responsible for ARIA.

Multipronged diagnostic and therapeutic strategies for Alzheimer's disease

Alzheimer's disease (AD) is a progressive neurodegenerative disorder and a major contributor to dementia cases worldwide. AD is clinically characterized by learning, memory, and cognitive deficits. The accumulation of extracellular amyloid β (Aβ) plaques and neurofibrillary tangles (NFTs) of tau are the pathological hallmarks of AD and are explored as targets for clinical diagnosis and therapy. AD pathology is poorly understood and there are no fully approved diagnosis and treatments. Notwithstanding the gap, decades of research in understanding disease mechanisms have revealed the multifactorial nature of AD. As a result, multipronged and holistic approaches are pertinent to targeting multiple biomarkers and targets for developing effective diagnosis and therapeutics. In this perspective, recent developments in Aβ and tau targeted diagnostic and therapeutic tools are discussed. Novel indirect, combination, and circulating biomarkers as potential diagnostic targets are highlighted. We underline the importance of multiplexing and multimodal detection of multiple biomarkers to generate biomarker fingerprints as a reliable diagnostic strategy. The classical therapeutics targeting Aβ and tau aggregation pathways are described with bottlenecks in the strategy. Drug discovery efforts targeting multifaceted toxicity involving protein aggregation, metal toxicity, oxidative stress, mitochondrial damage, and neuroinflammation are highlighted. Recent efforts focused on multipronged strategies to rationally design multifunctional modulators targeting multiple pathological factors are presented as future drug development strategies to discover potential therapeutics for AD.

Recent Treatment Strategies in Alzheimer's Disease and Chronic Traumatic Encephalopathy

Neurotrauma has been well linked to the progression of neurodegenerative disease. Much work has been done characterizing chronic traumatic encephalopathy, but less has been done regarding the contribution to Alzheimer's Disease. This review focuses on AD and its association with neurotrauma. Emerging clinical trials are discussed as well as novel mechanisms. We then address how some of these mechanisms are shared with CTE and emerging pre-clinical studies. This paper is a user-friendly resource that summarizes the emerging findings and proposes further investigation into key areas of interest. It is intended to serve as a catalyst for both research teams and clinicians in the quest to improve effective treatment and diagnostic options.

Monocyte biomarkers define sargramostim treatment outcomes for Parkinson's disease

Background

Dysregulation of innate and adaptive immunity heralds both the development and progression of Parkinson's disease (PD). Deficits in innate immunity in PD are defined by impairments in monocyte activation, function, and pro‐inflammatory secretory factors. Each influences disease pathobiology.

Methods and Results

To define monocyte biomarkers associated with immune transformative therapy for PD, changes in gene and protein expression were evaluated before and during treatment with recombinant human granulocyte‐macrophage colony‐stimulating factor (GM‐CSF, sargramostim, Leukine^®). Monocytes were recovered after leukapheresis and isolation by centrifugal elutriation, before and 2 and 6 months after initiation of treatment. Transcriptome and proteome biomarkers were scored against clinical motor functions. Pathway enrichments from single cell‐RNA sequencing and proteomic analyses from sargramostim‐treated PD patients demonstrate a neuroprotective signature, including, but not limited to, antioxidant, anti‐inflammatory, and autophagy genes and proteins (LRRK2, HMOX1, TLR2, TLR8, RELA, ATG7, and GABARAPL2).

Conclusions

This monocyte profile provides an “early” and unique biomarker strategy to track clinical immune‐based interventions, but requiring validation in larger case studies.

Foresee novel targets for Alzheimer's disease by investigating repurposed drugs

BACKGROUND

Alzheimer's Disease (AD) is the most rampant neurodegenerative disorder which has caused havoc worldwide. More than a century has passed since the first case of AD was reported, but still no stable treatment is known to mankind. The available medications only provide temporary relief and are not a cure for the disease. The hunt for advanced techniques in drug development has paved the way for drug repurposing, i.e., repositioning or reutilizing drugs as an innovative approach.

METHODOLOGY

Several drugs which were repurposed for AD were collected by following PRISMA 2020 systemic review. Databases like PubMed, ScienceDirect, JSTOR, and SciELO were used for data extraction. Further, Drugbank database was used to download all the identified drugs. Later, the Swiss Target Prediction tool was used to identify protein receptors for these drugs and the biological pathway followed by them.

RESULTS

Drugs like Zileuton, Salbutamol, Baricitinib, Carmustine, Paclitaxel, and Nilotinib were observed to be involved in regulation of neurotransmitters. Similarly, Metformin, Liraglutide, UDCA, and Bexarotene are involved in protein kinase cascades which also is one of the prime processes in metabolic disorders like AD. Furthermore, drugs like Rosiglitazone, Pioglitazone, and Lonafarnib are involved in interleukin-3 biosynthetic processes, which is again one of the most important processes studied in AD treatment.

CONCLUSION

The study concluded that the reviewed drugs that follow similar biological and molecular processes can be repurposed for AD if chosen judiciously with current medications and thus drug repurposing is a promising approach that can be utilized to find a cure for AD within a brief time and fewer resources compared to de novo drug synthesis. Although certain loopholes still need to be worked upon, the technique has great prospects. Furthermore, in silico methods can be utilized to justify the findings and identify the best drug candidate.

Altered Blood and Brain Expression of Inflammation and Redox Genes in Alzheimer's Disease, Common to APPV717I × TAUP301L Mice and Patients

Despite intensive research, the pathophysiology of Alzheimer’s disease (AD) is still not fully understood, and currently there are no effective treatments. Therefore, there is an unmet need for reliable biomarkers and animal models of AD to develop innovative therapeutic strategies addressing early pathologic events such as neuroinflammation and redox disturbances. The study aims to identify inflammatory and redox dysregulations in the context of AD-specific neuronal cell death and DNA damage, using the APP^V717I× TAU^P301L (AT) mouse model of AD. The expression of 84 inflammatory and 84 redox genes in the hippocampus and peripheral blood of double transgenic AT mice was evaluated against age-matched controls. A distinctive gene expression profile in the hippocampus and the blood of AT mice was identified, addressing DNA damage, apoptosis and thrombosis, complemented by inflammatory factors and receptors, along with ROS producers and antioxidants. Gene expression dysregulations that are common to AT mice and AD patients guided the final selection of candidate biomarkers. The identified inflammation and redox genes, common to AD patients and AT mice, might be valuable candidate biomarkers for preclinical drug development that could be readily translated to clinical trials.

Transcranial Electromagnetic Treatment “Rebalances” Blood and Brain Cytokine Levels in Alzheimer’s Patients: A New Mechanism for Reversal of Their Cognitive Impairment

Background

The immune system plays a critical role in the development and progression of Alzheimer’s disease (AD). However, there is disagreement as to whether development/progression of AD involves an over-activation or an under-activation of the immune system. In either scenario, the immune system’s cytokine levels are abnormal in AD and in need of rebalancing. We have recently published a pilot clinical trial (https://clinicaltrials.gov/ct2/show/NCT02958930) showing that 2 months of daily in-home Transcranial Electromagnetic Treatment (TEMT) was completely safe and resulted in reversal of AD cognitive impairment.

Methods

For the eight mild/moderate AD subjects in this published work, the present study sought to determine if their TEMT administration had immunologic effects on blood or CSF levels of 12 cytokines. Subjects were given daily in-home TEMT for 2 months by their caregivers, utilizing first-in-class MemorEM™ devices.

Results

For eight plasma cytokines, AD subjects with lower baseline cytokine levels always showed increases in those cytokines after both a single treatment or after 2-months of daily TEMT. By contrast, those AD subjects with higher baseline cytokine levels in plasma showed treatment-induced decreases in plasma cytokines at both time points. Thus, a gravitation to reported normal plasma cytokine levels (i.e., a “rebalancing”) occurred with both acute and long-term TEMT. In the CSF, TEMT-induced a similar rebalancing for seven measurable cytokines, the direction and extent of changes in individual subjects also being linked to their baseline CSF levels.

Conclusion

Our results strongly suggest that daily TEMT to AD subjects for 2-months can “rebalance” levels for 11 of 12 cytokines in blood and/or brain, which is associated with reversal of their cognitive impairment. TEMT is likely to be providing these immunoregulatory effects by affecting cytokine secretion from: (1) blood cells traveling through the head’s vasculature, and (2) the brain’s microglia/astrocytes, choroid plexus, or neurons. This rebalancing of so many cytokines, and in both brain and systemic compartments, appears to be a remarkable new mechanism of TEMT action that may contribute substantially to it’s potential to prevent, stop, or reverse AD and other diseases of aging.

Interleukin-2 expands neuroprotective regulatory T cells in Parkinson's disease

Background

Pharmacological approaches that boost neuroprotective regulatory T cell (Treg) number and function lead to neuroprotective activities in neurodegenerative disorders.

Objectives

We investigated whether low-dose interleukin 2 (IL-2) expands Treg populations and protects nigrostriatal dopaminergic neurons in a model of Parkinson's disease (PD).

Methods

IL-2 at 2.5 × 104 IU/dose/mouse was administered for 5 days. Lymphocytes were isolated and phenotype determined by flow cytometric analyses. To 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) intoxicated mice, 0.5 × 106 of enriched IL-2-induced Tregs were adoptively transferred to assess the effects on nigrostriatal neuron survival.

Results

IL-2 increased frequencies of CD4+CD25+CD127lowFoxP3+ Tregs that express ICOS and CD39 in blood and spleen. Adoptive transfer of IL-2-induced Tregs to MPTP-treated recipients increased tyrosine hydroxylase (TH)+ nigral dopaminergic neuronal bodies by 51% and TH+ striatal termini by 52% compared to control MPTP-treated animal controls.

Conclusions

IL-2 expands numbers of neuroprotective Tregs providing a vehicle for neuroprotection of nigrostriatal dopaminergic neurons in a pre-clinical PD model.

Tiny Toes to Tau Tangles: Down's Syndrome and Its Association With Alzheimer's Disease

Down’s syndrome (DS) is a common genetic condition caused by the trisomy of chromosome 21, which leads to the development of many multisystemic complications, early-onset Alzheimer’s disease (AD) being one of its most common complications. In this article, we have performed an intensive literature review that established a strong relationship between AD and DS. These two conditions are clubbed pathologically, clinically, and diagnostically to understand the association between AD and DS. This article focuses on understanding the impact of AD on a DS patient on both clinical and pathological levels and exploring some advanced treatment modalities. It has also emphasized the importance of early screening and diagnosis for AD in this group of patients to prevent AD development. Regular monitoring, early diagnosis, and a proper treatment plan can slow the AD occurrence in DS patients.

GM-CSF Promotes Immune Response and Survival in a Mouse Model of COVID-19

COVID-19 results in increased expression of inflammatory cytokines, but inflammation-targeting clinical trials have yielded poor to mixed results. Our studies of other disorders with an inflammatory component, including Alzheimer's disease, chemobrain, Down syndrome, normal aging, and West Nile Virus infection, showed that treatment with the 'pro-inflammatory' cytokine granulocyte-macrophage colony stimulating factor (GM-CSF) in humans or mouse models alleviated clinical, behavioral, and pathological features. We proposed that human recombinant GM-CSF (sargramostim) be repurposed to promote both the innate and adaptive immune responses in COVID-19 to reduce viral load and mortality1. Here, we report the results of a placebo-controlled study of GM-CSF in human ACE2 transgenic mice inoculated intranasally with SARS-CoV2 virus, a model of COVID-19. Infection resulted in high viral titers in lungs and brains and over 85% mortality. GM-CSF treatment beginning one day after infection increased anti-viral antibody titers, lowered mean lung viral titers proportionately (p=0.0020) and increased the odds of long-term survival by up to 5.8-fold (p=0.0358), compared to placebo. These findings suggest that, as an activator of both the innate and adaptive immune systems, GM-CSF/sargramostim may be an effective COVID-19 therapy with the potential to protect from re-infection more effectively than treatment with antiviral drugs or monoclonal antibodies.

Disease-Modifying Therapies for Alzheimer's Disease: More Questions than Answers

Scientific advances over the last four decades have steadily infused the Alzheimer's disease (AD) field with great optimism that therapies targeting Aβ, amyloid, tau, and innate immune activation states in the brain would provide disease modification. Unfortunately, this optimistic scenario has not yet played out. Though a recent approval of the anti-Aβ aggregate binding antibody, Aduhelm (aducanumab), as a "disease-modifying therapy for AD" is viewed by some as a breakthrough, many remain unconvinced by the data underlying this approval. Collectively, we have not succeeded in changing AD from a largely untreatable, inevitable, and incurable disease to a treatable, preventable, and curable one. Here, I will review the major foci of the AD "disease-modifying" therapeutic pipeline and some of the "open questions" that remain in terms of these therapeutic approaches. I will conclude the review by discussing how we, as a field, might adjust our approach, learning from our past failures to ensure future success.

Alzheimer's disease clinical trial update 2019-2021

The current clinical trial landscape targeting Alzheimer's disease (AD) is reviewed in the context of studies completed from 2019 to 2021. This review focuses on available data for observational and phase II/III clinical trial results, which will have the most impact on the field. ClinicalTrials.gov, the United States (US) comprehensive federal registry, was queried to identify completed trials. There are currently 226 interventional clinical trials and 51 observational studies completed, suspended, terminated, or withdrawn within our selected time frame. This review reveals that the role of biomarkers is expanding and although many lessons have been learned, many challenges remain when targeting disease modification of AD through amyloid and tau. In addition, to halt or slow clinical progression of AD, new clinical and observational trials are focusing on prevention as well as the role of more diverse biological processes known to influence AD pathology.

Innate Immune System Activation and Neuroinflammation in Down Syndrome and Neurodegeneration: Therapeutic Targets or Partners?

Innate immune system activation and inflammation are associated with and may contribute to clinical outcomes in people with Down syndrome (DS), neurodegenerative diseases such as Alzheimer's disease (AD), and normal aging. In addition to serving as potential diagnostic biomarkers, innate immune system activation and inflammation may play a contributing or causal role in these conditions, leading to the hypothesis that effective therapies should seek to dampen their effects. However, recent intervention studies with the innate immune system activator granulocyte-macrophage colony-stimulating factor (GM-CSF) in animal models of DS, AD, and normal aging, and in an AD clinical trial suggest that activating the innate immune system and inflammation may instead be therapeutic. We consider evidence that DS, AD, and normal aging are accompanied by innate immune system activation and inflammation and discuss whether and when during the disease process it may be therapeutically beneficial to suppress or promote such activation.

Sargramostim (rhu GM-CSF) as Cancer Therapy (Systematic Review) and An Immunomodulator. A Drug Before Its Time?

BACKGROUND

Sargramostim [recombinant human granulocyte-macrophage colony-stimulating factor (rhu GM-CSF)] was approved by US FDA in 1991 to accelerate bone marrow recovery in diverse settings of bone marrow failure and is designated on the list of FDA Essential Medicines, Medical Countermeasures, and Critical Inputs. Other important biological activities including accelerating tissue repair and modulating host immunity to infection and cancer via the innate and adaptive immune systems are reported in pre-clinical models but incompletely studied in humans.

OBJECTIVE

Assess safety and efficacy of sargramostim in cancer and other diverse experimental and clinical settings.

METHODS AND RESULTS

We systematically reviewed PubMed, Cochrane and TRIP databases for clinical data on sargramostim in cancer. In a variety of settings, sargramostim after exposure to bone marrow-suppressing agents accelerated hematologic recovery resulting in fewer infections, less therapy-related toxicity and sometimes improved survival. As an immune modulator, sargramostim also enhanced anti-cancer responses in solid cancers when combined with conventional therapies, for example with immune checkpoint inhibitors and monoclonal antibodies.

CONCLUSIONS

Sargramostim accelerates hematologic recovery in diverse clinical settings and enhances anti-cancer responses with a favorable safety profile. Uses other than in hematologic recovery are less-well studied; more data are needed on immune-enhancing benefits. We envision significantly expanded use of sargramostim in varied immune settings. Sargramostim has the potential to reverse the immune suppression associated with sepsis, trauma, acute respiratory distress syndrome (ARDS) and COVID-19. Further, sargramostim therapy has been promising in the adjuvant setting with vaccines and for anti-microbial-resistant infections and treating autoimmune pulmonary alveolar proteinosis and gastrointestinal, peripheral arterial and neuro-inflammatory diseases. It also may be useful as an adjuvant in anti-cancer immunotherapy.

Immunotherapies for Neurodegenerative Diseases

The current treatments for neurodegenerative diseases are mostly symptomatic without affecting the underlying cause of disease. Emerging evidence supports a potential role for immunotherapy in the management of disease progression. Numerous reports raise the exciting prospect that either the immune system or its derivative components could be harnessed to fight the misfolded and aggregated proteins that accumulate in several neurodegenerative diseases. Passive and active vaccinations using monoclonal antibodies and specific antigens that induce adaptive immune responses are currently under evaluation for their potential use in the development of immunotherapies. In this review, we aim to shed light on prominent immunotherapeutic strategies being developed to fight neuroinflammation-induced neurodegeneration, with a focus on innovative immunotherapies such as vaccination therapy.

Alzheimer and Purinergic Signaling: Just a Matter of Inflammation?

Alzheimer's disease (AD) is a widespread neurodegenerative pathology responsible for about 70% of all cases of dementia. Adenosine is an endogenous nucleoside that affects neurodegeneration by activating four membrane G protein-coupled receptor subtypes, namely P1 receptors. One of them, the A_2A subtype, is particularly expressed in the brain at the striatal and hippocampal levels and appears as the most promising target to counteract neurological damage and adenosine-dependent neuroinflammation. Extracellular nucleotides (ATP, ADP, UTP, UDP, etc.) are also released from the cell or are synthesized extracellularly. They activate P2X and P2Y membrane receptors, eliciting a variety of physiological but also pathological responses. Among the latter, the chronic inflammation underlying AD is mainly caused by the P2X7 receptor subtype. In this review we offer an overview of the scientific evidence linking P1 and P2 mediated purinergic signaling to AD development. We will also discuss potential strategies to exploit this knowledge for drug development.

Anti-Neurodegenerative Benefits of Acetylcholinesterase Inhibitors in Alzheimer's Disease: Nexus of Cholinergic and Nerve Growth Factor Dysfunction

Alzheimer's disease (AD) is a progressive neurodegenerative disorder that is increasingly viewed as a complex multi-dimensional disease without effective treatments. Recent randomized, placebo-controlled studies have shown volume losses of ~0.7% and ~3.5% per year, respectively, in the basal cholinergic forebrain (CBF) and hippocampus in untreated suspected prodromal AD. One year of donepezil treatment reduced these annualized rates of atrophy to about half of untreated rates. Similar positive although variable results have also been found in volumetric measurements of the cortex and whole brain in patients with mild cognitive impairment as well as more advanced AD stages after treatments with all three currently available acetylcholinesterase (AChE) inhibitors (donepezil, rivastigmine, and galantamine). Here we review the anti-neurodegenerative benefits of AChE inhibitors and the expected parallel disease-accelerating impairments caused by anticholinergics, within a framework of the cholinergic hypothesis of AD and AD-associated loss of nerve growth factor (NGF). Consistent with the "loss of trophic factor hypothesis of AD," we propose that AChE inhibitors enhance acetylcholine-dependent release and uptake of NGF, thereby sustaining cholinergic neuronal viability and thus slowing AD-associated degeneration of the CBF, to ultimately delay dementia progression. We propose that improved cholinergic therapies for AD started early in asymptomatic persons, especially those with risk factors, will delay the onset, progression, or emergence of dementia. The currently available competitive and pseudo- irreversible AChE inhibitors are not CNS-selective and thus induce gastrointestinal toxicity that limits cortical AChE inhibition to ~30% (ranges from 19% to 41%) as measured by in vivo PET studies in patients undergoing therapy. These levels of inhibition are marginal relative to what is required for effective symptomatic treatment of dementia or slowing AD-associated neurodegeneration. In contrast, because of the inherently slow de novo synthesis of AChE in the CNS (about one-- tenth the rate of synthesis in peripheral tissues), irreversible AChE inhibitors produce significantly higher levels of inhibition in the CNS than in peripheral tissues. For example, methanesulfonyl fluoride, an irreversible inhibitor reduces CNS AChE activity by ~68% in patients undergoing therapy and ~80% in cortical biopsies of non-human primates. The full therapeutic benefits of AChE inhibitors, whether for symptomatic treatment of dementia or disease-slowing, thus would benefit by producing high levels of CNS inhibition. One way to obtain such higher levels of CNS AChE inhibition would be by using irreversible inhibitors.