Results of a follow-up study to the randomized Alzheimer's Disease Anti-inflammatory Prevention Trial (ADAPT)

Neuroinflammation: A Driving Force in the Onset and Progression of Alzheimer's Disease

Background/Objectives: The goal of this commentary is to highlight several key components of the inflammatory process as it relates to amyloid toxicity in Alzheimer's disease (AD), including the role of neuroinflammatory factors and peripheral inflammatory events. Methods: Google Scholar and PubMed were used to find articles with the following keywords: Alzheimer's disease, amyloids, neuroinflammation, peripheral inflammation, microglia, cytokines, and treatments. Sources that were case reports, not peer-reviewed, or older than 30 years were excluded. Abstracts were reviewed first for their relevance before the full text was considered. Methods sections were reviewed to ensure the interventional papers included were randomized controlled trials, meta-analyses, or systematic reviews; however, several literature reviews were also included due to the relevance of their background information. Results: Based on the literature review, we chose to concentrate on microglia, cytokine signaling, and peripheral inflammation markers. We found that microglia activation and subsequent microglia-driven inflammation play a pivotal role in the pathomechanism of AD. Additionally, cytokines such as interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-a) appear to contribute to amyloid accumulation and cell damage. Finally, the increased permeability of the blood-brain barrier (BBB) allows for the peripheral inflammatory process to contribute to the inflammation of the central nervous system (CNS) and amyloid-beta (Aβ) accumulation. Conclusions: Current evidence suggests that the immune system plays a pivotal role in the pathogenesis of AD, both in the CNS and the periphery.

Metabolic and Immune System Dysregulation: Unraveling the Connections between Alzheimer's Disease, Diabetes, Inflammatory Bowel Diseases, and Rheumatoid Arthritis

Alzheimer's disease (AD), diabetes mellitus (DM), inflammatory bowel diseases (IBD), and rheumatoid arthritis (RA) are chronic conditions affecting millions globally. Despite differing clinical symptoms, these diseases share pathophysiological mechanisms involving metabolic and immune system dysregulation. This paper examines the intricate connections between these disorders, focusing on shared pathways such as insulin resistance, lipid metabolism dysregulation, oxidative stress, and chronic inflammation. An important aspect is the role of amyloid-beta plaques and tau protein tangles, which are hallmark features of AD. These protein aggregates are influenced by metabolic dysfunction and inflammatory processes similar to those seen in DM, RA, and IBD. This manuscript explores how amyloid and tau pathologies may be exacerbated by shared metabolic and immune dysfunction. Additionally, this work discusses the gut-brain axis and the influence of gut microbiota in mediating disease interactions. Understanding these commonalities opens new avenues for multi-targeted therapeutic approaches that address the root causes rather than merely the symptoms of these conditions. This integrative perspective could lead to more effective interventions and improved patient outcomes, emphasizing the importance of a unified approach in managing these interconnected diseases.

Exploring the Pathophysiology of Long COVID: The Central Role of Low-Grade Inflammation and Multisystem Involvement

Long COVID (LC), also referred to as Post COVID-19 Condition, Post-Acute Sequelae of SARS-CoV-2 Infection (PASC), and other terms, represents a complex multisystem disease persisting after the acute phase of COVID-19. Characterized by a myriad of symptoms across different organ systems, LC presents significant diagnostic and management challenges. Central to the disorder is the role of low-grade inflammation, a non-classical inflammatory response that contributes to the chronicity and diversity of symptoms observed. This review explores the pathophysiological underpinnings of LC, emphasizing the importance of low-grade inflammation as a core component. By delineating the pathogenetic relationships and clinical manifestations of LC, this article highlights the necessity for an integrated approach that employs both personalized medicine and standardized protocols aimed at mitigating long-term consequences. The insights gained not only enhance our understanding of LC but also inform the development of therapeutic strategies that could be applicable to other chronic conditions with similar pathophysiological features.

Rheumatoid arthritis is a protective factor against Alzheimer's disease: a bidirectional two-sample Mendelian randomization study

BACKGROUND

Epidemiological evidence suggests that there is an association between rheumatoid arthritis (RA) and Alzheimer's disease (AD). However, the causal relationship between RA and AD remains unclear. Therefore, this study aimed to investigate the causal relationship between RA and AD.

METHODS

Using publicly available genome-wide association study datasets, bidirectional two-sample Mendelian randomization (TSMR) was performed using the inverse-variance weighted (IVW), weighted median, MR‒Egger regression, simple mode, and weighted mode methods.

RESULTS

The results of MR for the causal effect of RA on AD (IVW, odds ratio [OR] = 0.959, 95% confidence interval [CI]: 0.941-0.978, P = 2.752E-05; weighted median, OR = 0.960, 95% CI: 0.937-0.984, P = 0.001) revealed a causal association between genetic susceptibility to RA and an increased risk of AD. The results of MR for the causal effect of AD on RA (IVW, OR = 0.978, 95% CI: 0.906-1.056, P = 0.576; weighted median, OR = 0.966, 95% CI: 0.894-1.043, P = 0.382) indicated that there was no causal association between genetic susceptibility to AD and an increased risk of RA.

CONCLUSIONS

The results of this two-way two-sample Mendelian randomization analysis revealed a causal association between genetic susceptibility to RA and a reduced risk of AD but did not reveal a causal association between genetic susceptibility to AD and an increased or reduced risk of RA.

Associations between the use of common nonsteroidal anti-inflammatory drugs, genetic susceptibility and dementia in participants with chronic pain: A prospective study based on 194,758 participants from the UK Biobank

OBJECTIVE

To investigate the potential relationship between common nonsteroidal anti-inflammatory drugs (NSAIDs), genetic susceptibility and all-cause dementia (ACD), Alzheimer's disease (AD), and vascular dementia (VD) among individuals experiencing chronic pain.

METHODS

This study was based on 194,758 chronic pain participants form UK biobank with a median follow-up of 13.7 years. Participants were categorized into different NSAIDs painkiller regimen groups: No NSAIDs group, Aspirin group, Ibuprofen group, Paracetamol group, and 2-3 NSAIDs group. Cox proportional risk models were used to examine the correlation between regular NSAIDs usage and the risk of ACD, AD, and VD. In addition, we further performed subgroup analyses and sensitivity analyses.

RESULTS

1) Compared to the No NSAIDs group, the aspirin group (HR = 1.12, 95% CI:1.01-1.24, P < 0.05), the paracetamol group (HR = 1.15, 95% CI:1.05-1.27, P < 0.01), and the 2-3 NSAIDs group (HR = 1.2, 95% CI:1.08-1.33, P < 0.05) showed a higher risk of ACD. Furthermore, the 2-3 NSAIDs group was also associated with a higher risk of VD (HR = 1.39, 95% CI: 1.08-1.33, P < 0.05). 2) At high dementia GRS participants with chronic pain, the paracetamol group (HR = 1.2, 95% CI: 1.03-1.43, P < 0.05) and the NSAIDs group (HR = 1.3, 95% CI: 1.07-1.59, P < 0.05) were associated with a higher risk of ACD compared to the no painkiller group. 3) There was no significant association between ibuprofen use and higher risk of dementia.

CONCLUSION

In individuals with chronic pain, the use of aspirin and paracetamol was associated with a higher risk of ACD, whereas the use of ibuprofen was not significantly associated with a higher risk of ACD.

Hydrocortisone Mitigates Alzheimer's-Related Cognitive Decline through Modulating Oxidative Stress and Neuroinflammation

Alzheimer's disease (AD), an age-related degenerative disorder, is characterized by β-amyloid deposition, abnormal phosphorylation of tau proteins, synaptic dysfunction, neuroinflammation, and oxidative stress. Despite extensive research, there are no medications or therapeutic interventions to completely treat and reverse AD. Herein, we explore the potential of hydrocortisone (HC), a natural and endogenous glucocorticoid known to have potent anti-inflammatory properties, in an Aβ1-42-induced AD mouse model. Our investigation highlights the beneficial effects of HC administration on cognitive impairment, synaptic function enhancement, and neuronal protection in Aβ1-42-induced AD mice. Notably, HC treatment effectively suppresses the hyperactivation of microglia and astrocytes, leading to a reduction in proinflammatory factors and alleviation of neuroinflammation. Furthermore, HC intervention demonstrates the capacity to mitigate the generation of ROS and oxidative stress. These compelling findings underscore the potential therapeutic application of HC in AD and present promising opportunities for its utilization in AD prevention and treatment. The implications drawn from our findings indicate that hydrocortisone holds promise as a viable candidate for adjunctive use with other anti-AD drugs for the clinical management of patients presenting with moderate to severe AD.

Unlocking Modifiable Risk Factors for Alzheimer's Disease: Does the Oral Microbiome Hold Some of the Keys?

Advancing age is recognized as the primary risk factor for Alzheimer's disease (AD); however approximately one third of dementia cases are attributable to modifiable risk factors such as hypertension, diabetes, smoking, and obesity. Recent research also implicates oral health and the oral microbiome in AD risk and pathophysiology. The oral microbiome contributes to the cerebrovascular and neurodegenerative pathology of AD via the inflammatory, vascular, neurotoxic, and oxidative stress pathways of known modifiable risk factors. This review proposes a conceptual framework that integrates the emerging evidence regarding the oral microbiome with established modifiable risk factors. There are numerous mechanisms by which the oral microbiome may interact with AD pathophysiology. Microbiota have immunomodulatory functions, including the activation of systemic pro-inflammatory cytokines. This inflammation can affect the integrity of the blood-brain barrier, which in turn modulates translocation of bacteria and their metabolites to brain parenchyma. Amyloid-β is an antimicrobial peptide, a feature which may in part explain its accumulation. There are microbial interactions with cardiovascular health, glucose tolerance, physical activity, and sleep, suggesting that these modifiable lifestyle risk factors of dementia may have microbial contributors. There is mounting evidence to suggest the relevance of oral health practices and the microbiome to AD. The conceptual framework presented here additionally demonstrates the potential for the oral microbiome to comprise a mechanistic intermediary between some lifestyle risk factors and AD pathophysiology. Future clinical studies may identify specific oral microbial targets and the optimum oral health practices to reduce dementia risk.

Microglia activation in central nervous system disorders: A review of recent mechanistic investigations and development efforts

Microglia are the principal resident immune cells in the central nervous system (CNS) and play important roles in the development of CNS disorders. In recent years, there have been significant developments in our understanding of microglia, and we now have greater insight into the temporal and spatial patterns of microglia activation in a variety of CNS disorders, as well as the interactions between microglia and neurons. A variety of signaling pathways have been implicated. However, to date, all published clinical trials have failed to demonstrate efficacy over placebo. This review summarizes the results of recent important studies and attempts to provide a mechanistic view of microglia activation, inflammation, tissue repair, and CNS disorders.

The gut microbiota in neurodegenerative diseases: revisiting possible therapeutic targets for cannabidiol

Understanding the pathophysiology of Alzheimer's disease (AD) is essential to improve the efficacy of treatments and, consequently, patients' lives. Unfortunately, traditional therapeutic strategies have not been effective. There is therefore an urgent need to discover or develop alternative treatment strategies. Recently, some pieces of the puzzle appear to emerge: on a hand, the gut microbiota (GM) has gained attention since intestinal dysbiosis aggravates and generates some of the pathological processes of AD; on the other hand, cannabidiol (CBD), a phytocannabinoid, attenuates intestinal inflammation and possesses neuroprotective properties. Intestinal dysbiosis (increased population of proinflammatory bacteria) in AD increases plasma lipopolysaccharide and Aβ peptide levels, both responsible for increasing the permeability of the blood-brain barrier (BBB). A leaky BBB may facilitate the entry of peripheral inflammatory mediators into the central nervous system and ultimately aggravate neuroinflammation and neuronal death due to chronic activation of glial cells. Studies investigating the GM reported a strong relationship between intestinal dysbiosis and AD. In this review we conjecture that the GM is a promising therapeutic target for CBD in the context of AD.

Vagus nerve stimulated by microbiota-derived hydrogen sulfide mediates the regulation of berberine on microglia in transient middle cerebral artery occlusion rats

Amelioration of neuroinflammation via modulating microglia is a promising approach for cerebral ischemia therapy. The aim of the present study was to explore gut-brain axis signals in berberine-modulating microglia polarization following cerebral ischemia. The potential pathway was determined through analyzing the activation of the vagus nerve, hydrogen sulfide (H₂ S) metabolism, and cysteine persulfides of transient receptor potential vanilloid 1 (TRPV1) receptor. The cerebral microenvironment feature was explored with a metabolomics assay. The data indicated that berberine ameliorated behavioral deficiency in transient middle cerebral artery occlusion rats through modulating microglia polarization and neuroinflammation depending on microbiota. Enhanced vagus nerve activity following berberine treatment was blocked by antibiotic cocktails, capsazepine, or sodium molybdate, respectively. Berberine-induced H₂ S production was responsible for vagus nerve stimulation achieved through assimilatory and dissimilatory sulfate reduction with increased synthetic enzymes. Sulfation of the TRPV1 receptor resulted in vagus nerve activation and promoted the c-fos and ChAT in the nucleus tractus solitaries with berberine. Sphingolipid metabolism is the primary metabolic characteristic with berberine in the cerebral cortex, hippocampus, and cerebral spinal fluid disrupted by antibiotics. Berberine, in conclusion, modulates microglia polarization in a microbiota-dependent manner. H₂ S stimulates the vagus nerve through TRPV1 is responsible for the berberine-induced gut-brain axis signal transmission. Sphingolipid metabolism might mediate the neuroinflammation amelioration following vagus afferent fiber activation.

Microglia Polarization From M1 to M2 in Neurodegenerative Diseases

Microglia-mediated neuroinflammation is a common feature of neurodegenerative diseases such as Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), and multiple sclerosis (MS). Microglia can be categorized into two opposite types: classical (M1) or alternative (M2), though there’s a continuum of different intermediate phenotypes between M1 and M2, and microglia can transit from one phenotype to another. M1 microglia release inflammatory mediators and induce inflammation and neurotoxicity, while M2 microglia release anti-inflammatory mediators and induce anti-inflammatory and neuroprotectivity. Microglia-mediated neuroinflammation is considered as a double-edged sword, performing both harmful and helpful effects in neurodegenerative diseases. Previous studies showed that balancing microglia M1/M2 polarization had a promising therapeutic prospect in neurodegenerative diseases. We suggest that shifting microglia from M1 to M2 may be significant and we focus on the modulation of microglia polarization from M1 to M2, especially by important signal pathways, in neurodegenerative diseases.

A tale of two systems: Lessons learned from female mid-life aging with implications for Alzheimer's prevention & treatment

Neurological aging is frequently viewed as a linear process of decline, whereas in reality, it is a dynamic non-linear process. The dynamic nature of neurological aging is exemplified during midlife in the female brain. To investigate fundamental mechanisms of midlife aging that underlie risk for development of Alzheimer's disease (AD) in late life, we investigated the brain at greatest risk for the disease, the aging female brain. Outcomes of our research indicate that mid-life aging in the female is characterized by the emergence of three phases: early chronological (pre-menopause), endocrinological (peri-menopause) and late chronological (post-menopause) aging. The endocrinological aging program is sandwiched between early and late chronological aging. Throughout the three stages of midlife aging, two systems of biology, metabolic and immune, are tightly integrated through a network of signaling cascades. The network of signaling between these two systems of biology underlie an orchestrated sequence of adaptative starvation responses that shift the brain from near exclusive dependence on a single fuel, glucose, to utilization of an auxiliary fuel derived from lipids, ketone bodies. The dismantling of the estrogen control of glucose metabolism during mid-life aging is a critical contributor to the shift in fuel systems and emergence of dynamic neuroimmune phenotype. The shift in fuel reliance, puts the largest reservoir of local fatty acids, white matter, at risk for catabolism as a source of lipids to generate ketone bodies through astrocytic beta oxidation. APOE4 genotype accelerates the tipping point for emergence of the bioenergetic crisis. While outcomes derived from research conducted in the female brain are not directly translatable to the male brain, the questions addressed in a female centric program of research are directly applicable to investigation of the male brain. Like females, males with AD exhibit deficits in the bioenergetic system of the brain, activation of the immune system and hallmark Alzheimer's pathologies. The drivers and trajectory of mechanisms underlying neurodegeneration in the male brain will undoubtedly share common aspects with the female in addition to factors unique to the male. Preclinical and clinical evidence indicate that midlife endocrine aging can also be a transitional bridge to autoimmune disorders. Collectively, the data indicate that endocrinological aging is a critical period "tipping point" in midlife which can initiate emergence of the prodromal stage of late-onset-Alzheimer's disease. Interventions that target both immune and metabolic shifts that occur during midlife aging have the potential to alter the trajectory of Alzheimer's risk in late life. Further, to achieve precision medicine for AD, chromosomal sex is a critical variable to consider along with APOE genotype, other genetic risk factors and stage of disease.

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.

Neuroinflammation and Oxidative Stress in Alzheimer's Disease; Can Nutraceuticals and Functional Foods Come to the Rescue?

Alzheimer's disease (AD), the most prevalent form of age-related dementia, is typified by progressive memory loss and spatial awareness with personality changes. The increasing socioeconomic burden associated with AD has made it a focus of extensive research. Ample scientific evidence supports the role of neuroinflammation and oxidative stress in AD pathophysiology, and there is increasing research into the possible role of anti-inflammatory and antioxidative agents as disease modifying therapies. While, the result of numerous preclinical studies has demonstrated the benefits of anti-inflammatory agents, these benefits however have not been replicated in clinical trials, necessitating a further search for more promising anti-inflammatory agents. Current understanding highlights the role of diet in the development of neuroinflammation and oxidative stress, as well as the importance of dietary interventions and lifestyle modifications in mitigating them. The current narrative review examines scientific literature for evidence of the roles (if any) of dietary components, nutraceuticals and functional foods in the prevention or management of AD. It also examines how diet/ dietary components could modulate oxidative stress/inflammatory mediators and pathways that are crucial to the pathogenesis and/or progression of AD.

The Current Landscape of Prevention Trials in Dementia

As the prevalence of dementia and Alzheimer's disease (AD) increases worldwide, it is imperative to reflect on the major clinical trials in the prevention of dementia and the challenges that surround them. The pharmaceutical industry has focused on developing drugs that primarily affect the Aβ cascade and tau proteinopathy, while academics have focused on repurposed therapeutics and multi-domain interventions for prevention studies. This paper highlights significant primary, secondary, and tertiary prevention trials for dementia and AD, overall design, methods, and systematic issues to better understand the current landscape of prevention trials. We included 32 pharmacologic intervention trials and 9 multi-domain trials. Fourteen could be considered primary prevention, and 18 secondary or tertiary prevention trials. Major categories were Aβ vaccines, Aβ antibodies, tau antibodies, anti-inflammatories, sex hormones, and Ginkgo biloba extract. The 9 multi-domain studies mainly focused on lifestyle modifications such as blood pressure management, socialization, and physical activity. The lack of validated drug targets, and the complexity of the diagnostic frameworks, eligibility criteria, and outcome measurements for trials, make it difficult to show efficacy for both pharmacological and multi-domain interventions. We hope that this summative analysis of trials will stimulate discussion for scientists and clinicians interested in reviewing and developing preventative interventions for AD.

Microglia in Alzheimer's Disease: a Key Player in the Transition Between Homeostasis and Pathogenesis

Immune activation accompanies the development of proteinopathy in the brains of Alzheimer's dementia patients. Evolving from the long-held viewpoint that immune activation triggers the pathological trajectory in Alzheimer's disease, there is accumulating evidence now that microglial activation is neither pro-amyloidogenic nor just a simple reactive process to the proteinopathy. Preclinical studies highlight an interesting aspect of immunity, i.e., spurring immune system activity may be beneficial under certain circumstances. Indeed, a dynamic evolving relationship between different activation states of the immune system and its neuronal neighbors is thought to regulate overall brain organ health in both healthy aging and progression of Alzheimer's dementia. A new premise evolving from genome, transcriptome, and proteome data is that there might be at least two major phases of immune activation that accompany the pathological trajectory in Alzheimer's disease. Though activation on a chronic scale will certainly lead to neurodegeneration, this emerging knowledge of a potential beneficial aspect of immune activation allows us to form holistic insights into when, where, and how much immune system activity would need to be tuned to impact the Alzheimer's neurodegenerative cascade. Even with the trove of recently emerging -omics data from patients and preclinical models, how microglial phenotypes are functionally related to the transition of a healthy aging brain towards progressive degenerative state remains unknown. A deeper understanding of the synergism between microglial functional states and brain organ health could help us discover newer interventions and therapies that enable us to address the current paucity of disease-modifying therapies in Alzheimer's disease.

Anti-Inflammatory Agents: An Approach to Prevent Cognitive Decline in Alzheimer's Disease

Systemic inflammation is an organism's response to an assault by the non-self. However, that inflammation may predispose humans to illnesses targeted to organs, including Alzheimer's disease (AD). Lesions in AD have pro-inflammatory cytokines and activated microglial/monocyte/macrophage cells. Up to this point, clinical trials using anti-amyloid monoclonal antibodies have not shown success. Maybe it is time to look elsewhere by combating inflammation. Neuroinflammation with CNS cellular activation and excessive expression of immune cytokines is suspected as the "principal culprit" in the higher risk for sporadic AD. Microglia, the resident immune cell of the CNS, perivascular myeloid cells, and activated macrophages produce IL-1, IL-6 at higher levels in patients with AD. Anti-inflammatory measures that target cellular/cytokine-mediated damage provide a rational therapeutic strategy. We propose a clinical trial using oral type 1 IFNs to act as such an agent; one that decreases IL-1 and IL-6 secretion by activating lamina propria lymphocytes in the gut associated lymphoid tissue with subsequent migration to the brain undergoing inflammatory responses. A clinical trial would be double-blind, parallel 1-year clinical trial randomized 1 : 1 oral active type 1 IFN versus best medical therapy to determine whether ingested type I IFN would decrease the rate of cognitive decline in mild cognitive impairment or mild AD. Using cognitive psychometrics, imaging, and fluid biomarkers (MxA for effective type I IFN activity beyond the gut), we can determine if oral type I IFN can prevent cognitive decline in AD.

Hydrophilic polymer driven crystallization self-assembly: an inflammatory multi-drug combination nanosystem against Alzheimer's disease

The hydrophobic polymer driven crystallization of self-assembled micelles is usually sufficient for their purposes in materials chemistry studies. However, with the state of smart drug delivery research, micelles alone are not enough. The principles of the self assembly driven by hydrophilic dextran brushes together with charged poly(3-acrylamidophenyl boronic acid) (PPBA) are uncovered in this study. A series of poly(ε-caprolactone)-block-poly(3-acrylamidophenyl boronic acid)-dextran (PCL-b-PPBA-Dex) micelles and vesicles are investigated as potential Alzheimer's disease (AD) treatments. Three inflammatory microenvironment responsive micelles, including celecoxib drug-loaded micelles (CEL), ibuprofen drug-loaded micelles (IBU) and telmisartan drug-loaded micelles (TEL), are developed. In vivo, CEL/IBU (mixture of CEL and IBU) and CEL/TEL (mixture of CEL and TEL) suppress the activation of glia and reduce the levels of inflammatory mediators through eliminating cyclooxygenase 2 (COX-2) signals. The CEL/TEL combination nanosystem is better at correcting neuroinflammation and improving the spatial memory ability of a senescence-accelerated mouse prone 8 model (SAMP8). We consider that the inflammation responsive combination nanosystem provides a new potential treatment for AD clinical patients.

Macrocyclic Immunoproteasome Inhibitors as a Potential Therapy for Alzheimer's Disease

Previously, we reported that immunoproteasome (iP)-targeting linear peptide epoxyketones improve cognitive function in mouse models of Alzheimer's disease (AD) in a manner independent of amyloid β. However, these compounds' clinical prospect for AD is limited due to potential issues, such as poor brain penetration and metabolic instability. Here, we report the development of iP-selective macrocyclic peptide epoxyketones prepared by a ring-closing metathesis reaction between two terminal alkenes attached at the P2 and P3/P4 positions of linear counterparts. We show that a lead macrocyclic compound DB-60 (20) effectively inhibits the catalytic activity of iP in ABCB1-overexpressing cells (IC50: 105 nM) and has metabolic stability superior to its linear counterpart. DB-60 (20) also lowered the serum levels of IL-1α and ameliorated cognitive deficits in Tg2576 mice. The results collectively suggest that macrocyclic peptide epoxyketones have improved CNS drug properties than their linear counterparts and offer promising potential as an AD drug candidate.

The informed road map to prevention of Alzheimer Disease: A call to arms

Alzheimer disease (AD) prevention trials hold the promise to delay or prevent cognitive decline and dementia onset by intervening before significant neuronal damage occurs. In recent years, the first AD prevention trials have launched and are yielding important findings on the biology of targeting asymptomatic AD pathology. However, there are limitations that impact the design of these prevention trials, including the translation of animal models that recapitulate key stages and multiple pathological aspects of the human disease, missing target validation in asymptomatic disease, uncertain causality of the association of pathophysiologic changes with cognitive and clinical symptoms, and limited biomarker validation for novel targets. The field is accelerating advancements in key areas including the development of highly specific and quantitative biomarker measures for AD pathology, increasing our understanding of the course and relationship of amyloid and tau pathology in asymptomatic through symptomatic stages, and the development of powerful interventions that can slow or reverse AD amyloid pathology. We review the current status of prevention trials and propose key areas of needed research as a call to basic and translational scientists to accelerate AD prevention. Specifically, we review (1) sporadic and dominantly inherited primary and secondary AD prevention trials, (2) proposed targets, mechanisms, and drugs including the amyloid, tau, and inflammatory pathways and combination treatments, (3) the need for more appropriate prevention animal models and experiments, and (4) biomarkers and outcome measures needed to design human asymptomatic prevention trials. We conclude with actions needed to effectively move prevention targets and trials forward.

Antimicrobial α-defensins as multi-target inhibitors against amyloid formation and microbial infection

Amyloid aggregation and microbial infection are considered as pathological risk factors for developing amyloid diseases, including Alzheimer's disease (AD), type II diabetes (T2D), Parkinson's disease (PD), and medullary thyroid carcinoma (MTC). Due to the multifactorial nature of amyloid diseases, single-target drugs and treatments have mostly failed to inhibit amyloid aggregation and microbial infection simultaneously, thus leading to marginal benefits for amyloid inhibition and medical treatments. Herein, we proposed and demonstrated a new "anti-amyloid and antimicrobial hypothesis" to discover two host-defense antimicrobial peptides of α-defensins containing β-rich structures (human neutrophil peptide of HNP-1 and rabbit neutrophil peptide of NP-3A), which have demonstrated multi-target, sequence-independent functions to (i) prevent the aggregation and misfolding of different amyloid proteins of amyloid-β (Aβ, associated with AD), human islet amyloid polypeptide (hIAPP, associated with T2D), and human calcitonin (hCT, associated with MTC) at sub-stoichiometric concentrations, (ii) reduce amyloid-induced cell toxicity, and (iii) retain their original antimicrobial activity upon the formation of complexes with amyloid peptides. Further structural analysis showed that the sequence-independent amyloid inhibition function of α-defensins mainly stems from their cross-interactions with amyloid proteins via β-structure interactions. The discovery of antimicrobial peptides containing β-structures to inhibit both microbial infection and amyloid aggregation greatly expands the new therapeutic potential of antimicrobial peptides as multi-target amyloid inhibitors for better understanding pathological causes and treatments of amyloid diseases.

Creating and validating a DNA methylation-based proxy for interleukin-6

Background

Studies evaluating the relationship between chronic inflammation and cognitive functioning have produced heterogeneous results. A potential reason for this is the variability of inflammatory mediators which could lead to misclassifications of individuals’ persisting levels of inflammation. DNA methylation (DNAm) has shown utility in indexing environmental exposures and could be leveraged to provide proxy signatures of chronic inflammation.

Method

We conducted an elastic net regression of interleukin-6 (IL-6) in a cohort of 875 older adults (Lothian Birth Cohort 1936; mean age: 70 years) to develop a DNAm-based predictor. The predictor was tested in an independent cohort (Generation Scotland; N = 7028 [417 with measured IL-6], mean age: 51 years).

Results

A weighted score from 35 CpG sites optimally predicted IL-6 in the independent test set (Generation Scotland; R² = 4.4%, p = 2.1 × 10⁻⁵). In the independent test cohort, both measured IL-6 and the DNAm proxy increased with age (serum IL-6: n = 417, β = 0.02, SE = 0.004, p = 1.3 × 10⁻⁷; DNAm IL-6 score: N = 7028, β = 0.02, SE = 0.0009, p < 2 × 10⁻¹⁶). Serum IL-6 did not associate with cognitive ability (n = 417, β = −0.06, SE = 0.05, p = .19); however, an inverse association was identified between the DNAm score and cognitive functioning (N = 7028, β = −0.16, SE = 0.02, p_FDR < 2 × 10⁻¹⁶).

Conclusions

These results suggest methylation-based predictors can be used as proxies for inflammatory markers, potentially allowing for further insight into the relationship between inflammation and pertinent health outcomes.

Ideational Fluency in Patients with Rheumatoid Arthritis

BACKGROUND

Neuropsychiatric symptoms have been well documented in several systemic inflammatory conditions, for example, systemic lupus erythematosus (SLE). Increased prevalence of cognitive decline and psychiatric issues has been reported in patients with rheumatoid arthritis (RA). However, there is limited evidence of which exact cognitive domains are affected and to what degree.

AIM

To test the performance of cognition in the domain of ideational fluency (Thing Categories Test in particular) in patients with RA and compare the results with the general population and to the results with cognitive and depression screening scores in both groups.

METHODS

Patient Health Questionnaire 9 (PHQ-9), Generalized Anxiety Disorder 7 (GAD-7) assessment, Montreal Cognitive Assessment (MoCA), and Thing Categories Test (TCT) were used to evaluate patients with RA, as well as the control group.

RESULTS

Twenty patients with RA and 20 controls were tested, with 7 and 4 men, and 13 and 16 women in the study and control group, respectively. Average scores in TCT at three minutes were 7.50 (IQR6.0-10.0) and 6.0 (IQR3.0-8.0) for category "blue"; 17.50 (IQR15.0-19.0) and 16.0 (10.0-18.0) for category "round" in the control and study group, respectively. A statistically significant difference was established between the study and the control group in TCT for the category "blue" (p<0.025). The average score for GAD7 was 2.0 (IQR 0.0-5.75) and 3.0 (IQR0.50-6.00) in the control and study group, respectively. The average score for PHQ-9 was 2.0 (IQR0.25-4.75) and 4.0 (IQR2.00-5.50) in the control and study group, respectively. Finally, the average score for the MoCA scale was 27.0 (IQR25.25-28.00) and 26.0 (IQR23.50-28.00) in the control and study group, respectively.

CONCLUSION

Preliminary evidence suggests that RA at least partially affects the cognitive domain of ideational fluency. However, further research with larger experimental groups is needed to provide more conclusive evidence.

Potential Roles of Myeloid Differentiation Factor 2 on Neuroinflammation and Its Possible Interventions

Neuroinflammation is the primary response by immune cells in the nervous system to protect against infection. Chronic and uncontrolled neuroinflammation triggers neuronal injury and neuronal death resulting in a variety of neurodegenerative disorders. Therefore, fine tuning of the immune response in the nervous system is now extensively considered as a potential therapeutic intervention for those diseases. The immune cells of the nervous system express Toll-like receptor 4 (TLR4) together with myeloid differentiation factor 2 (MD-2) to protect against the pathogens. Over the last 10 years, antagonists targeting the functional domains of MD-2 have become attractive pharmacological intervention strategies in pre-clinical studies into neuroinflammation and its associated brain pathologies. This review aims to summarize and discuss the roles of TLR4-MD-2 signaling pathway activation in various models of neuroinflammation. This review article also highlights the studies reporting the effect of MD-2 antagonists on neuroinflammation in in vitro and in vivo studies.

New hybrids of tacrine and indomethacin as multifunctional acetylcholinesterase inhibitors

A new series of hybrid compounds were designed, consisting of anti-AChE and BuChE activity components with an anti-inflammatory component. A series of 9-amino-1,2,3,4-tetrahydroacridine and indomethacin derivatives were synthesized. All compounds were created using alkyldiamine with different chain lengths as a linker. Various biological activities were evaluated, including inhibitory activity against AChE and BuChE. The tested compounds showed high inhibitory activities against cholinesterases. The IC50 values for all compounds ranging from 10 nM to 7 µM. The potency of inhibition was much higher than well-known AChE and BuChE inhibitors (tacrine and donepezil). Compound 3h had the strongest inhibitory activity; kinetic studies showed it to have a mixed-type of acetylcholinesterase inhibition properties. The cytotoxicity of the newly-synthesized compounds against HepG2 (hepatocarcinoma cells) and EA.hy96 (human vein endothelial cells) cell lines was determined using the MTT and MTS tests. All investigated compounds presented similar cytotoxic activity against HepG2 and EA.hy926 cell line, ranged in micromolar values. Compounds with longer linkers showed higher antioxidant activity. The most active compound was 3h. Docking studies confirmed interactions with important regions of AChE and BuChE. Its multifunctional properties, i.e. high activity against AChE and BuChE, antioxidant activity and low cytotoxicity, highlight 3h as a promising agent for the treatment of AD.

Anti-inflammatories in Alzheimer's disease-potential therapy or spurious correlate?

Epidemiological evidence suggests non-steroidal anti-inflammatory drugs reduce the risk of Alzheimer’s disease. However, clinical trials have found no evidence of non-steroidal anti-inflammatory drug efficacy. This incongruence may be due to the wrong non-steroidal anti-inflammatory drugs being tested in robust clinical trials or the epidemiological findings being caused by confounding factors. Therefore, this study used logistic regression and the innovative approach of negative binomial generalized linear mixed modelling to investigate both prevalence and cognitive decline, respectively, in the Alzheimer’s Disease Neuroimaging dataset for each commonly used non-steroidal anti-inflammatory drug and paracetamol. Use of most non-steroidal anti-inflammatories was associated with reduced Alzheimer’s disease prevalence yet no effect on cognitive decline was observed. Paracetamol had a similar effect on prevalence to these non-steroidal anti-inflammatory drugs suggesting this association is independent of the anti-inflammatory effects and that previous results may be due to spurious associations. Interestingly, diclofenac use was significantly associated with both reduce incidence and slower cognitive decline warranting further research into the potential therapeutic effects of diclofenac in Alzheimer’s disease.

Randomized placebo-controlled trial of the effects of aspirin on dementia and cognitive decline

OBJECTIVE

To determine the effect of low-dose aspirin vs placebo on incident all-cause dementia, incident Alzheimer disease (AD), mild cognitive impairment (MCI), and cognitive decline in older individuals.

METHODS

Aspirin in Reducing Events in the Elderly (ASPREE) was a double-blind, placebo-controlled trial of low-dose aspirin. In the United States and Australia, community-dwelling individuals aged ≥70 years (US minorities ≥65 years) and free of cardiovascular disease, physical disability, and diagnosed dementia were enrolled. Participants were randomized 1:1-100 mg daily aspirin or placebo. The Modified Mini-Mental State Examination, Hopkins Verbal Learning Test-Revised, Symbol Digit Modalities Test, and Controlled Oral Word Association Test assessed cognition at baseline and over follow-up. Additional cognitive testing was performed in participants with suspected dementia ("trigger") based on within-study assessments or clinical history. Dementia was adjudicated according to DSM-IV criteria. National Institute on Aging-Alzheimer's Association criteria were used for AD and MCI subclassification.

RESULTS

A total of 19,114 participants were followed over a median 4.7 years and 964 triggered further dementia assessments. There were 575 adjudicated dementia cases, and 41% were classified as clinically probable AD. There was no substantial difference in the risk of all dementia triggers (hazard ratio [HR], 1.03; 95% confidence interval [CI], 0.91-1.17), probable AD (HR, 0.96; 95% CI, 0.74-1.24), or MCI (HR, 1.12; 95% CI, 0.92-1.37) between aspirin and placebo. Cognitive change over time was similar in the aspirin and placebo groups.

CONCLUSIONS

There was no evidence that aspirin was effective in reducing risk of dementia, MCI, or cognitive decline. Follow-up of these outcomes after initial exposure is ongoing.

CLASSIFICATION OF EVIDENCE

This study provides Class II evidence that for healthy older individuals, low-dose aspirin does not significantly reduce the incidence of dementia, probable AD, MCI, or cognitive decline.

CLINICALTRIALSGOV IDENTIFIER

NCT01038583.

Deciphering Alzheimer's disease: predicting new therapeutic strategies via improved understanding of biology and pathogenesis

INTRODUCTION

There is no cure for Alzheimer's disease (AD). One explanation may pertain to the need to intervene as early as possible upstream from the accumulation of β-amyloid plaques and tau tangles.

AREAS COVERED

A PUBMED literature search was completed to review the biological or pathological changes at the basis of disease initiation; this includes neuroinflammation, oxidative stress, microbiome changes and glymphatic system dysfunction. Innovative therapeutic strategies based on these mechanisms are also discussed.

EXPERT OPINION

Improved understanding of the pathophysiological mechanisms that underly AD would assist in the identification of drug targets for clinical trials. Furthermore, pharmacokinetic and pharmacodynamic studies are key for the characterization of the properties of disease-modifying drugs and the improvement of their penetration of the blood-brain barrier. Drug targets can be examined at different stages of the disease, hence the importance of selecting and recruiting the appropriate participants, preferably at the earliest stage of AD. New trial designs should be established which primarily involve combination therapies that can work synergistically on common pathways. Going forward, innovative treatment strategies involving nanotechnology, young blood products transfusion and photobiomodulation also offer promise for the future.

Recruiting the innate immune system with GM-CSF to fight viral diseases, including West Nile Virus encephalitis and COVID-19

As the coronavirus disease 2019 (COVID-19) pandemic grows throughout the world, it is imperative that all approaches to ameliorating its effects be investigated, including repurposing drugs that show promise in other diseases. We have been investigating an approach to multiple disorders that involves recruiting the innate immune system to aid the body's healing and regenerative mechanism(s). In the case of West Nile Virus encephalitis and potentially COVID-19, the proposed intervention to stimulate the innate immune system may give the adaptive immune response the necessary time to develop, finish clearing the virus, and provide future immunity. Furthermore, we have found that GM-CSF-induced recruitment of the innate immune system is also able to reverse brain pathology, neuroinflammation and cognitive deficits in mouse models of Alzheimer's disease and Down syndrome, as well as improving cognition in normal aging and in human patients with cognitive deficits due to chemotherapy, both of which exhibit neuroinflammation. Others have shown that GM-CSF is an effective treatment for both bacterial and viral pneumonias, and their associated inflammation, in animals and that it has successfully treated pneumonia-associated Acute Respiratory Distress Syndrome in humans. These and other data strongly suggest that GM-CSF may be an effective treatment for many viral infections, including COVID-19.

A Path Toward Precision Medicine for Neuroinflammatory Mechanisms in Alzheimer's Disease

Neuroinflammation commences decades before Alzheimer's disease (AD) clinical onset and represents one of the earliest pathomechanistic alterations throughout the AD continuum. Large-scale genome-wide association studies point out several genetic variants—TREM2, CD33, PILRA, CR1, MS4A, CLU, ABCA7, EPHA1, and HLA-DRB5-HLA-DRB1—potentially linked to neuroinflammation. Most of these genes are involved in proinflammatory intracellular signaling, cytokines/interleukins/cell turnover, synaptic activity, lipid metabolism, and vesicle trafficking. Proteomic studies indicate that a plethora of interconnected aberrant molecular pathways, set off and perpetuated by TNF-α, TGF-β, IL-1β, and the receptor protein TREM2, are involved in neuroinflammation. Microglia and astrocytes are key cellular drivers and regulators of neuroinflammation. Under physiological conditions, they are important for neurotransmission and synaptic homeostasis. In AD, there is a turning point throughout its pathophysiological evolution where glial cells sustain an overexpressed inflammatory response that synergizes with amyloid-β and tau accumulation, and drives synaptotoxicity and neurodegeneration in a self-reinforcing manner. Despite a strong therapeutic rationale, previous clinical trials investigating compounds with anti-inflammatory properties, including non-steroidal anti-inflammatory drugs (NSAIDs), did not achieve primary efficacy endpoints. It is conceivable that study design issues, including the lack of diagnostic accuracy and biomarkers for target population identification and proof of mechanism, may partially explain the negative outcomes. However, a recent meta-analysis indicates a potential biological effect of NSAIDs. In this regard, candidate fluid biomarkers of neuroinflammation are under analytical/clinical validation, i.e., TREM2, IL-1β, MCP-1, IL-6, TNF-α receptor complexes, TGF-β, and YKL-40. PET radio-ligands are investigated to accomplish in vivo and longitudinal regional exploration of neuroinflammation. Biomarkers tracking different molecular pathways (body fluid matrixes) along with brain neuroinflammatory endophenotypes (neuroimaging markers), can untangle temporal–spatial dynamics between neuroinflammation and other AD pathophysiological mechanisms. Robust biomarker–drug codevelopment pipelines are expected to enrich large-scale clinical trials testing new-generation compounds active, directly or indirectly, on neuroinflammatory targets and displaying putative disease-modifying effects: novel NSAIDs, AL002 (anti-TREM2 antibody), anti-Aβ protofibrils (BAN2401), and AL003 (anti-CD33 antibody). As a next step, taking advantage of breakthrough and multimodal techniques coupled with a systems biology approach is the path to pursue for developing individualized therapeutic strategies targeting neuroinflammation under the framework of precision medicine.

Resveratrol promoted the M2 polarization of microglia and reduced neuroinflammation after cerebral ischemia by inhibiting miR-155

Purpose: Neuroinflammation was demonstrated to play an important role in the brain injury induced by cerebral ischemia, which was mainly mediated by microglia. MicroRNA-155 (MiR-155) was reported to promote the M1 polarization of microglia and increase neuroinflammation. Resveratrol was identified to have the ability to promote the M2 polarization of microglia and reduce inflammation. Whether resveratrol can promote the M2 polarization of microglia and further inhibit neuroinflammation after cerebral ischemia, and its correlation with miR-155 is unclear. To clarify this, we conducted this study to explore the potential of resveratrol as an effective strategy to treat cerebral ischemia induced neuroinflammation.Materials and methods:The cerebral ischemia mouse model was first constructed by middle cerebral artery occlusion (MCAO). Then resveratrol was intraperitoneally injected at 0 h, 8 h and 18 h after cerebral ischemia. Subsequently, the relative expression of miR-155 and the signature genes of M1 and M2 microglia in injured brain were measured by RT-PCR, and the concentration of pro-inflammatory and anti-inflammatory cytokines were detected by ELISA. Further, the in vitro experiments were also conducted to explore the effect of resveratrol on the inflammation mediated by LPS activated BV2 microglia.Results: Results indicated that the relative expression of miR-155 in ischemia brain and activated BV2 microglia was elevated, while resveratrol reduced the expression of miR-155. Resveratrol promoted the M2 polarization of microglia and reduced neuroinflammation in injured brain and activated BV2 microglia.Conclusions: In conclusion, this research indicated that resveratrol promoted the M2 polarization of microglia and reduced neuroinflammation after cerebral ischemia by inhibiting miR-155.

Prevalence of affective disorders and dementia in inflammatory polyarthropathies

Comorbid disorders are common in psychiatric diseases and understanding the risk of secondary diseases can aid successful clinical treatment. The objective of this study was to compare the frequency of comorbid dementia, affective disorders, and inflammatory polyarthropathies. Healthcare data obtained via the German Hospital Fees Act from two independent databases with more than 7.4 million cases were analyzed to compare the prevalence of comorbid disorders. Comorbid inflammatory polyarthropathy was observed in 2.27% of patients diagnosed with affective disorders and 1.35% of patients with dementia (p < 0.001). Among patients with a primary diagnosis of inflammatory polyarthropathy, 1.27% of patients were diagnosed with dementia, whereas 4.55% of age-matched patients without inflammatory polyarthropathies had comorbid dementia (p < 0.001). The opposite effect was demonstrated for affective disorders, as 5.77% of patients with a primary diagnosis of inflammatory polyarthropathy also had comorbid affective disorders, while 4.87% of age-matched patients without inflammatory polyarthropathy had an accompanying affective disease (p < 0.001). These findings show an association between the occurrence of inflammatory polyarthropathies, dementia, and affective disorders. This correlation might improve diagnosis and treatment for patients with comorbidities. Moreover, further exploration of the molecular pathophysiology underlying these relationships could be relevant for the development of novel treatment options.

Safety, tolerability, pharmacokinetics, and pharmacodynamics of low dose lysergic acid diethylamide (LSD) in healthy older volunteers

Research has shown that psychedelics, such as lysergic acid diethylamide (LSD), have profound anti-inflammatory properties mediated by 5-HT2A receptor signaling, supporting their evaluation as a therapeutic for neuroinflammation associated with neurodegenerative disease.

OBJECTIVE

This study evaluated the safety, tolerability, pharmacokinetics, and pharmacodynamics of orally repeated administration of 5 μg, 10 μg, and 20 μg LSD in older healthy individuals. In the current paper, we present safety, tolerability, pharmacokinetics, and pharmacodynamic measures that relate to safety, tolerability, and dose response.

METHODS

This was a phase 1 double-blind, placebo-controlled, randomized study. Volunteers were randomly assigned to 1 of 4 dose groups (5 μg, 10 μg, 20 μg LSD, and placebo), and received their assigned dose on six occasions (i.e., every 4 days).

RESULTS

Forty-eight older healthy volunteers (mean age = 62.9 years) received placebo (n = 12), 5 μg (n = 12), 10 μg (n = 12), or 20 μg (n = 12) LSD. LSD plasma levels were undetectable for the 5 μg group and peak blood plasma levels for the 10 μg and 20 μg groups occurred at 30 min. LSD was well tolerated, and the frequency of adverse events was no higher than for placebo. Assessments of cognition, balance, and proprioception revealed no impairment.

CONCLUSIONS

Our results suggest safety and tolerability of orally administered 5 μg, 10 μg, and 20 μg LSD every fourth day over a 21-day period and support further clinical development of LSD for the treatment and prevention of Alzheimer's disease (AD).

Influenza vaccination in early Alzheimer's disease rescues amyloidosis and ameliorates cognitive deficits in APP/PS1 mice by inhibiting regulatory T cells

Background

Alzheimer’s disease (AD) is a neurodegenerative disorder strongly correlated with a dysfunctional immune system. Our previous results demonstrated that inactivated influenza vaccine (IIV) facilitates hippocampal neurogenesis and blocks lipopolysaccharide (LPS)-induced cognitive impairment. However, whether IIV improves cognitive deficits in an AD mouse model remains unclear. In addition, early interventions in AD have been encouraged in recent years. Here, we investigated whether IIV immunization at the preclinical stage of AD alters the brain pathology and cognitive deficits in an APP/ PS1 mouse model.

Methods

We assessed spatial learning and memory using Morris water maze (MWM). The brain β-amyloid (Aβ) plaque burden and activated microglia were investigated by immunohistochemistry. Furthermore, flow cytometry was utilized to analyze the proportions of Treg cells in the spleen. A cytokine antibody array was performed to measure the alteration of cytokines in the brain and peripheral immune system.

Results

Five IIV immunizations activated microglia, reduced the Aβ burden and improved the cognitive impairment. Simultaneously, the IIV-induced immune response broke peripheral immunosuppression by reducing Foxp3⁺ regulatory T cell (Treg) activities, whereas the restoration of Treg level in the periphery using all-trans retinoic acid (ATRA) blunted the protective effects of IIV on Aβ burden and cognitive functions. Interestingly, IIV immunization might increase proinflammatory and anti-inflammatory cytokine expression in the brain of APP/PS1 mice, enhanced microglial activation, and enhanced the clustering and phagocytosis of Aβ, thereby creating new homeostasis in the disordered immune microenvironment.

Conclusions

Altogether, our results suggest that early multiple IIV immunizations exert a beneficial immunomodulatory effect in APP/PS1 mice by breaking Treg-mediated systemic immune tolerance, maintaining the activation of microglia and removing of Aβ plaques, eventually improving cognitive deficits.

A dual inhibitor of the proteasome catalytic subunits LMP2 and Y attenuates disease progression in mouse models of Alzheimer's disease

The immunoproteasome (iP) is a variant of the constitutive proteasome (cP) that is abundantly expressed in immune cells which can also be induced in somatic cells by cytokines such as TNF-α or IFN-γ. Accumulating evidence support that the iP is closely linked to multiple facets of inflammatory response, eventually leading to the development of several iP inhibitors as potential therapeutic agents for autoimmune diseases. Recent studies also found that the iP is upregulated in reactive glial cells surrounding amyloid β (Aβ) deposits in brains of Alzheimer’s disease (AD) patients, but the role it plays in the pathogenesis of AD remains unclear. In this study, we investigated the effects of several proteasome inhibitors on cognitive function in AD mouse models and found that YU102, a dual inhibitor of the iP catalytic subunit LMP2 and the cP catalytic subunit Y, ameliorates cognitive impairments in AD mouse models without affecting Aβ deposition. The data obtained from our investigation revealed that YU102 suppresses the secretion of inflammatory cytokines from microglial cells. Overall, this study indicates that there may exist a potential link between LMP2/Y and microglia-mediated neuroinflammation and that inhibition of these subunits may offer a new therapeutic strategy for AD.

Recommendations for Anti-inflammatory Treatments in Alzheimer's Disease: A Comprehensive Review of the Literature

Alzheimer’s disease (AD) is the most common cause of dementia in elderly patients, affecting individuals older than 60 years. It is a complex degenerative brain disease characterized by progressive cognitive impairment. AD constitutes a major global health concern. A central role for inflammation has been implicated in the pathogenesis of AD. Despite the understanding of multiple molecular pathways in the pathophysiology of AD, novel treatment agents with a possible role in modifying the disease activity are still lacking. Our article provides a comprehensive review of various observational studies and randomized trials encompassing the use of anti-inflammatory agents in the management of AD patients and utilizes the conclusions derived therefrom to give recommendations in this regard. 

Exploiting microglial and peripheral immune cell crosstalk to treat Alzheimer's disease

Neuroinflammation is considered one of the cardinal features of Alzheimer’s disease (AD). Neuritic plaques composed of amyloid β and neurofibrillary tangle-laden neurons are surrounded by reactive astrocytes and microglia. Exposure of microglia, the resident myeloid cell of the CNS, to amyloid β causes these cells to acquire an inflammatory phenotype. While these reactive microglia are important to contain and phagocytose amyloid plaques, their activated phenotype impacts CNS homeostasis. In rodent models, increased neuroinflammation promoted by overexpression of proinflammatory cytokines can cause an increase in hyperphosphorylated tau and a decrease in hippocampal function. The peripheral immune system can also play a detrimental or beneficial role in CNS inflammation. Systemic inflammation can increase the risk of developing AD dementia, and chemokines released directly by microglia or indirectly by endothelial cells can attract monocytes and T lymphocytes to the CNS. These peripheral immune cells can aid in amyloid β clearance or modulate microglia responses, depending on the cell type. As such, several groups have targeted the peripheral immune system to modulate chronic neuroinflammation. In this review, we focus on the interplay of immunomodulating factors and cell types that are being investigated as possible therapeutic targets for the treatment or prevention of AD.

Changing how we think about infectious diseases

As we learn more and more about the classes of organisms that infect humans, we are discovering that many organisms, including pathogenic organisms, may have a complex relationship with humans in which infection seldom results in the production disease. In some cases, infection may be just one biological event that occurs during a multievent process that develops sequentially, over time, and involves genetic and environmental factors that may vary among individuals. Consequently, the role of infectious organisms in the development of human disease may not meet all of the criteria normally required to determine when an organism can be called the cause of a disease. This chapter reviews the expanding role of infections in the development of human disease. We discuss prion diseases of humans, a fascinating example of an infectious disease-causing agent that is not a living organism. We also discuss the diseases of unknown etiology for which infectious organisms may play a role. In addition, this chapter reviews some of the misconceptions and recurring errors associated with the classification of infectious diseases that have led to misdiagnoses and have impeded our understanding of the role of organisms in the development of human diseases.

Inflammation: Bridging Age, Menopause and APOEε4 Genotype to Alzheimer's Disease

Neuro-inflammatory processes that contribute to development of Alzheimer’s are evident early in the latent prodromal phase and worsen during the course of the disease. Despite substantial mechanistic and clinical evidence of inflammation, therapeutic approaches targeting inflammation have failed to alter the course of the disease. Disparate results from epidemiological and clinical trials targeting inflammation, highlight the complexity of the inflammatory process. Herein we review the dynamics of the inflammatory process across aging, midlife endocrine transitions, and the APOEε4 genotype and their contribution to progression of Alzheimer’s disease (AD). We discuss the chronic inflammatory processes that are activated during midlife chronological and endocrine aging, which ultimately limit the clearance capacity of microglia and lead to immune senescence. Aging, menopause, and APOEε4 combine the three hits of a compromised bioenergetic system of menopause with the chronic low grade innate inflammation of aging with the APOEε4 dyslipidemia and adaptive immune response. The inflammatory immune response is the unifying factor that bridges across each of the risk factors for AD. Immune system regulators that are specific to stage of disease and inflammatory phenotype would provide a therapeutic strategy to disconnect the bridge that drives disease. Outcomes of this analysis provide plausible mechanisms underlying failed clinical trials of anti-inflammatory agents in Alzheimer’s patients. Further, they highlight the need for stratifying AD clinical trial cohorts based on inflammatory phenotype. Combination therapies that include targeted use of anti-inflammatory agent’s specific to the immune phenotype are considered.

Essential Dietary Bioactive Lipids in Neuroinflammatory Diseases

SIGNIFICANCE

Under physiological conditions, neurons and glia are in a healthy, redox-balanced environment; when injury perturbs this equilibrium, a neuroinflammatory state is established by activated microglia that triggers pro-inflammatory responses and alters the oxidant/antioxidant balance, thus leading to neuronal loss and neurodegeneration. In neurodegenerative diseases (such as Alzheimer's disease, Parkinson's disease, amyothrophic lateral sclerosis, and multiple sclerosis), the brain is in a constitutively self-sustaining cycle of inflammation and oxidative stress that prompts and amplifies brain damage. Recent Advances: Recently, an increasing amount of scientific data highlight the ability of specific nutrients to cross the blood-brain barrier, and to modulate inflammatory and oxidative pathways. Therefore, nutritional approaches may contribute to restore the lost equilibrium among factors accounting for neurodegeneration.

CRITICAL ISSUES

Herein, we critically examine how essential lipids (including fatty acids, liposoluble vitamins and phytosterols) might contribute to accelerate or prevent the onset and progression of such pathologies. In particular, we highlight that experimental and clinical findings, although promising, are still inadequate to draw definitive conclusions.

FUTURE DIRECTIONS

More research is warranted in order to establish the real impact of lipid intake on brain health, especially when redox balance and inflammatory responses have been already compromised. In the future, it would be hoped to gain a detailed knowledge of chemical modifications and dynamic properties of such nutrients, before planning to exploit them as potential therapeutics. Antioxid. Redox Signal. 29, 37-60.

Impact of the biological definition of Alzheimer's disease using amyloid, tau and neurodegeneration (ATN): what about the role of vascular changes, inflammation, Lewy body pathology?

BACKGROUND

The NIA-AA research framework proposes a biological definition of Alzheimer's disease, where asymptomatic persons with amyloid deposition would be considered as having this disease prior to symptoms.

DISCUSSION

Notwithstanding the fact that amyloid deposition in isolation is not associated with dementia, even the combined association of amyloid and tau pathology does not inevitably need to dementia over age 65. Other pathological factors may play a leading or an accelerating role in age-associated cognitive decline, including vascular small vessel disease, neuroinflammation and Lewy Body pathology.

CONCLUSION

Research should aim at understanding the interaction between all these factors, rather than focusing on them individually. Hopefully this will lead to a personalized approach to the prevention of brain aging, based on individual biological, genetic and cognitive profiles.

Celecoxib Prevents Cognitive Impairment and Neuroinflammation in Soluble Amyloid β-treated Rats

Recent findings suggest that soluble forms of amyloid-β (sAβ) peptide contribute to synaptic and cognitive dysfunctions in early stages of Alzheimer's disease (AD). On the other hand, neuroinflammation and cyclooxygenase-2 (COX-2) enzyme have gained increased interest as key factors involved early in AD, although the signaling pathways and pathophysiologic mechanisms underlying a link between sAβ-induced neurotoxicity and inflammation are still unclear. Here, we investigated the effects of selective COX-2 enzyme inhibition on neuropathological alterations induced by sAβ administration in rats. To this purpose, animals received an intracerebroventricular (icv) injection of predominantly monomeric forms of sAβ and, 7 days after, behavioral as well as biochemical parameters and neurotransmitter alterations were evaluated. During this period, rats also received a sub-chronic treatment with celecoxib. Biochemical results demonstrated that icv sAβ injection significantly increased both COX-2 and pro-inflammatory cytokines expression in the hippocampus (Hipp) of treated rats. In addition, the number of hypertrophic microglial cells and astrocytes were upregulated in sAβ-treated group. Interestingly, rats treated with sAβ showed long-term memory deficits, as confirmed by a significant reduction of discrimination index in the novel object recognition test, along with reduced brain-derived neurotrophic factor expression and increased noradrenaline levels in the Hipp. Systemic administration of celecoxib prevented behavioral dysfunctions, as well as biochemical and neurotransmitter alterations. In conclusion, our results suggest that sAβ neurotoxicity might be associated to COX-2-mediated inflammatory pathways and that early treatment with selective COX-2 inhibitor might provide potential remedies to counterbalance the sAβ-induced effects.

Involvement of Astrocytes in Alzheimer's Disease from a Neuroinflammatory and Oxidative Stress Perspective

Alzheimer disease (AD) is a frequent and devastating neurodegenerative disease in humans, but still no curative treatment has been developed. Although many explicative theories have been proposed, precise pathophysiological mechanisms are unknown. Due to the importance of astrocytes in brain homeostasis they have become interesting targets for the study of AD. Changes in astrocyte function have been observed in brains from individuals with AD, as well as in AD in vitro and in vivo animal models. The presence of amyloid beta (Aβ) has been shown to disrupt gliotransmission, neurotransmitter uptake, and alter calcium signaling in astrocytes. Furthermore, astrocytes express apolipoprotein E and are involved in the production, degradation and removal of Aβ. As well, changes in astrocytes that precede other pathological characteristics observed in AD, point to an early contribution of astroglia in this disease. Astrocytes participate in the inflammatory/immune responses of the central nervous system. The presence of Aβ activates different cell receptors and intracellular signaling pathways, mainly the advanced glycation end products receptor/nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway, responsible for the transcription of pro-inflammatory cytokines and chemokines in astrocytes. The release of these pro-inflammatory agents may induce cellular damage or even stimulate the production of Aβ in astrocytes. Additionally, Aβ induces the appearance of oxidative stress (OS) and production of reactive oxygen species and reactive nitrogen species in astrocytes, affecting among others, intracellular calcium levels, NADPH oxidase (NOX), NF-κB signaling, glutamate uptake (increasing the risk of excitotoxicity) and mitochondrial function. Excessive neuroinflammation and OS are observed in AD, and astrocytes seem to be involved in both. The Aβ/NF-κB interaction in astrocytes may play a central role in these inflammatory and OS changes present in AD. In this paper, we also discuss therapeutic measures highlighting the importance of astrocytes in AD pathology. Several new therapeutic approaches involving phenols (curcumin), phytoestrogens (genistein), neuroesteroids and other natural phytochemicals have been explored in astrocytes, obtaining some promising results regarding cognitive improvements and attenuation of neuroinflammation. Novel strategies comprising astrocytes and aimed to reduce OS in AD have also been proposed. These include estrogen receptor agonists (pelargonidin), Bambusae concretio Salicea, Monascin, and various antioxidatives such as resveratrol, tocotrienol, anthocyanins, and epicatechin, showing beneficial effects in AD models.

Xanthoceraside attenuates amyloid β peptide1-42-induced memory impairments by reducing neuroinflammatory responses in mice

Xanthoceraside, a novel triterpenoid saponin extracted from the husks of Xanthoceras sorbifolia Bunge, has neuroprotective effects in vivo and anti-inflammatory properties in vitro. However, the exact mechanism of xanthoceraside on anti-amyloid beta (Aβ)-induced neuroinflammatory responses has not been elucidated. Therefore, we used intracerebroventricular injection of amyloid _1-42 (Aβ_1-42) to establish a mouse model to test the effects of xanthoceraside on Aβ-induced cognitive impairments and the TLR2/NF-κB and MAPK pathways. The mice received xanthoceraside (0.02, 0.08 or 0.32mg/kg) or vehicle from the day of Aβ_1-42 injection. The Morris water maze test was performed 4 days after Aβ_1-42 injection. The levels of inflammatory cytokines (interleukin (IL)-6 and IL-4) were measured by enzyme-linked immunosorbent assay (ELISA). The expression levels of glial fibrillary acidic protein (GFAP) and cluster of differentiation 11b (CD11b) in the hippocampus were determined with an immunohistochemistry assay. Inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), nuclear factor κB (NF-κB) and mitogen-activated protein kinase (MAPK) were analysed by Western blotting; iNOS, COX-2 and Toll-like receptor 2 (TLR2) mRNA expression levels were measured by reverse transcription-polymerase chain reaction (RT-PCR). Here, we observed that xanthoceraside at doses of 0.08 and 0.32mg/kg significantly improved learning and memory impairments and significantly inhibited GFAP and CD11b overexpression induced by Aβ_1-42 in mice. ELISA results revealed that xanthoceraside suppressed IL-6 release and increased IL-4 levels. Western blotting results showed that xanthoceraside reduced iNOS and COX-2 protein levels in hippocampus; xanthoceraside also inhibited translocation of NF-κB p50 and p65 into the nucleus and phosphorylation of extracellular signal-regulated kinase (ERK), Jun N-terminal kinase (JNK) and p38. RT-PCR confirmed that xanthoceraside decreased iNOS, COX-2 and TLR2 mRNA levels. These results suggest that xanthoceraside inhibition of the TLR2 pathway and down-regulation of MAPK and NF-κB activities may be related to the improvement in learning and memory impairments.

NSAID Use and Incident Cognitive Impairment in a Population-based Cohort

Nonsteroidal anti-inflammatory drugs (NSAIDs) may prevent dementia, but previous studies have yielded conflicting results. This study estimated the association of prior NSAID use with incident cognitive impairment in the population-based Epidemiology of Hearing Loss Study (EHLS, n=2422 without cognitive impairment in 1998-2000). Prospectively collected medication data from 1988-1990, 1993-1995, and 1998-2000 were used to categorize NSAID use history at the cognitive baseline (1998-2000). Aspirin use and nonaspirin NSAID use were separately examined. Cox regression models were used to estimate the associations between NSAID use history at baseline and incident cognitive impairment in 2003-2005 or 2009-2010. Logistic regression analyses were used to estimate associations with a second outcome, mild cognitive impairment/dementia, available in 2009-2010. Participants using aspirin at baseline but not 5 years prior were more likely to develop cognitive impairment (adjusted hazard ratio=1.77; 95% confidence interval=1.11, 2.82; model 2), with nonsignificant associations for longer term use. Nonaspirin NSAID use was not associated with incident cognitive impairment or mild cognitive impairment/dementia odds. These results provided no evidence to support a potential protective effect of NSAIDs against dementia.