Aβ Amyloid Pathology Affects the Hearts of Patients With Alzheimer's Disease: Mind the Heart

Diastolic dysfunction in Alzheimer's disease model mice is associated with Aβ-amyloid aggregate formation and mitochondrial dysfunction

Alzheimer's Disease (AD) is a progressive neurodegenerative disease caused by the deposition of Aβ aggregates or neurofibrillary tangles. AD patients are primarily diagnosed with the concurrent development of several cardiovascular dysfunctions. While few studies have indicated the presence of intramyocardial Aβ aggregates, none of the studies have performed detailed analyses for pathomechanism of cardiac dysfunction in AD patients. This manuscript used aged APPSWE/PS1 Tg and littermate age-matched wildtype (Wt) mice to characterize cardiac dysfunction and analyze associated pathophysiology. Detailed assessment of cardiac functional parameters demonstrated the development of diastolic dysfunction in APPSWE/PS1 Tg hearts compared to Wt hearts. Muscle function evaluation showed functional impairment (decreased exercise tolerance and muscle strength) in APPSWE/PS1 Tg mice. Biochemical and histochemical analysis revealed Aβ aggregate accumulation in APPSWE/PS1 Tg mice myocardium. APPSWE/PS1 Tg mice hearts also demonstrated histopathological remodeling (increased collagen deposition and myocyte cross-sectional area). Additionally, APPSWE/PS1 Tg hearts showed altered mitochondrial dynamics, reduced antioxidant protein levels, and impaired mitochondrial proteostasis compared to Wt mice. APPSWE/PS1 Tg hearts also developed mitochondrial dysfunction with decreased OXPHOS and PDH protein complex expressions, altered ETC complex dynamics, decreased complex activities, and reduced mitochondrial respiration. Our results indicated that Aβ aggregates in APPSWE/PS1 Tg hearts are associated with defects in mitochondrial respiration and complex activities, which may collectively lead to cardiac diastolic dysfunction and myocardial pathological remodeling.

Unraveling the relationship among insulin resistance, IGF-1, and amyloid-beta 1-40: Is the definition of type 3 diabetes applicable in the cardiovascular field?

The concept of "type 3 diabetes" has emerged to define alterations in glucose metabolism that predispose individuals to the development of Alzheimer's disease (AD). Novel evidence suggests that changes in the insulin/insulin-like growth factor 1 (IGF-1)/growth hormone (GH) axis, which are characteristic of Diabetes Mellitus, are one of the major factors contributing to excessive amyloid-beta (Aβ) production and neurodegenerative processes in AD. Moreover, molecular findings suggest that insulin resistance and dysregulated IGF-1 signaling promote atherosclerosis via endothelial dysfunction and a pro-inflammatory state. As the pathophysiological role of Aβ1-40 in patients with cardiovascular disease has attracted attention due to its involvement in plaque formation and destabilization, it is of great interest to explore whether a paradigm similar to that in AD exists in the cardiovascular field. Therefore, this review aims to elucidate the intricate interplay between insulin resistance, IGF-1, and Aβ1-40 in the cardiovascular system and assess the applicability of the type 3 diabetes concept. Understanding these relationships may offer novel therapeutic targets and diagnostic strategies to mitigate cardiovascular risk in patients with insulin resistance and dysregulated IGF-1 signaling.

PICALM Regulating the Generation of Amyloid β-Peptide to Promote Anthracycline-Induced Cardiotoxicity

Anthracyclines are chemotherapeutic drugs used to treat solid and hematologic malignancies. However, life-threatening cardiotoxicity, with cardiac dilation and heart failure, is a drawback. A combination of in vivo for single cell/nucleus RNA sequencing and in vitro approaches is used to elucidate the underlying mechanism. Genetic depletion and pharmacological blocking peptides on phosphatidylinositol binding clathrin assembly (PICALM) are used to evaluate the role of PICALM in doxorubicin-induced cardiotoxicity in vivo. Human heart tissue samples are used for verification. Patients with end-stage heart failure and chemotherapy-induced cardiotoxicity have thinner cell membranes compared to healthy controls do. Using the doxorubicin-induced cardiotoxicity mice model, it is possible to replicate the corresponding phenotype in patients. Cellular changes in doxorubicin-induced cardiotoxicity in mice, especially in cardiomyocytes, are identified using single cell/nucleus RNA sequencing. Picalm expression is upregulated only in cardiomyocytes with doxorubicin-induced cardiotoxicity. Amyloid β-peptide production is also increased after doxorubicin treatment, which leads to a greater increase in the membrane permeability of cardiomyocytes. Genetic depletion and pharmacological blocking peptides on Picalm reduce the generation of amyloid β-peptide. This alleviates the doxorubicin-induced cardiotoxicity in vitro and in vivo. In human heart tissue samples of patients with chemotherapy-induced cardiotoxicity, PICALM, and amyloid β-peptide are elevated as well.

Alzheimer disease blood biomarkers: considerations for population-level use

In the past 5 years, we have witnessed the first approved Alzheimer disease (AD) disease-modifying therapy and the development of blood-based biomarkers (BBMs) to aid the diagnosis of AD. For many reasons, including accessibility, invasiveness and cost, BBMs are more acceptable and feasible for patients than a lumbar puncture (for cerebrospinal fluid collection) or neuroimaging. However, many questions remain regarding how best to utilize BBMs at the population level. In this Review, we outline the factors that warrant consideration for the widespread implementation and interpretation of AD BBMs. To set the scene, we review the current use of biomarkers, including BBMs, in AD. We go on to describe the characteristics of typical patients with cognitive impairment in primary care, who often differ from the patient populations used in AD BBM research studies. We also consider factors that might affect the interpretation of BBM tests, such as comorbidities, sex and race or ethnicity. We conclude by discussing broader issues such as ethics, patient and provider preference, incidental findings and dealing with indeterminate results and imperfect accuracy in implementing BBMs at the population level.

Amyloid-beta and tau protein beyond Alzheimer's disease

ABSTRACT

The aggregation of amyloid-beta peptide and tau protein dysregulation are implicated to play key roles in Alzheimer's disease pathogenesis and are considered the main pathological hallmarks of this devastating disease. Physiologically, these two proteins are produced and expressed within the normal human body. However, under pathological conditions, abnormal expression, post-translational modifications, conformational changes, and truncation can make these proteins prone to aggregation, triggering specific disease-related cascades. Recent studies have indicated associations between aberrant behavior of amyloid-beta and tau proteins and various neurological diseases, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis, as well as retinal neurodegenerative diseases like Glaucoma and age-related macular degeneration. Additionally, these proteins have been linked to cardiovascular disease, cancer, traumatic brain injury, and diabetes, which are all leading causes of morbidity and mortality. In this comprehensive review, we provide an overview of the connections between amyloid-beta and tau proteins and a spectrum of disorders.

Extracellular vesicles mediate inflammasome signaling in the brain and heart of Alzheimer's disease mice

Introduction

Alzheimer's disease (AD) is an inflammatory neurodegenerative disease characterized by memory loss and cognitive impairment that worsens over time. AD is associated with many comorbidities, including cardiovascular disease that are associated with poorer outcomes. Comorbidities, especially heart disease and stroke, play a significant role in the demise of AD patients. Thus, it is important to understand how comorbidities are linked to AD. We have previously shown that extracellular vesicle (EV)-mediated inflammasome signaling plays an important role in the pathogenesis of brain injury and acute lung injury after traumatic brain injury.

Methods

We analyzed the cortical, hippocampal, ventricular, and atrial protein lysates from APP/PS1 mice and their respective controls for inflammasome signaling activation. Additionally, we analyzed serum-derived EV for size, concentration, and content of inflammasome proteins as well as the EV marker CD63. Finally, we performed conditioned media experiments of EV from AD patients and healthy age-matched controls delivered to cardiovascular cells in culture to assess EV-induced inflammation.

Results

We show a significant increase in Pyrin, NLRP1, caspase-1, and ASC in the brain cortex whereas caspase-8, ASC, and IL-1β were significantly elevated in the heart ventricles of AD mice when compared to controls. We did not find significant differences in the size or concentration of EV between groups, but there was a significant increase of caspase-1 and IL-1β in EV from AD mice compared to controls. In addition, conditioned media experiments of serum-derived EV from AD patients and age-matched controls delivered to cardiovascular cells in culture resulted in inflammasome activation, and significant increases in TNF-α and IL-2.

Conclusion

These results indicate that EV-mediated inflammasome signaling in the heart may play a role in the development of cardiovascular diseases in AD patients.

Interactions between nanoparticles and pathological changes of vascular in Alzheimer's disease

Emerging evidence suggests that vascular pathological changes play a pivotal role in the pathogenesis of Alzheimer's disease (AD). The dysfunction of the cerebral vasculature occurs in the early course of AD, characterized by alterations in vascular morphology, diminished cerebral blood flow (CBF), impairment of the neurovascular unit (NVU), vasculature inflammation, and cerebral amyloid angiopathy. Vascular dysfunction not only facilitates the influx of neurotoxic substances into the brain, triggering inflammation and immune responses but also hampers the efflux of toxic proteins such as Aβ from the brain, thereby contributing to neurodegenerative changes in AD. Furthermore, these vascular changes significantly impact drug delivery and distribution within the brain. Therefore, developing targeted delivery systems or therapeutic strategies based on vascular alterations may potentially represent a novel breakthrough in AD treatment. This review comprehensively examines various aspects of vascular alterations in AD and outlines the current interactions between nanoparticles and pathological changes of vascular.

Unraveling the mechanisms of NK cell dysfunction in aging and Alzheimer's disease: insights from GWAS and single-cell transcriptomics

Background

Aging is an important factor in the development of Alzheimer's disease (AD). The senescent cells can be recognized and removed by NK cells. However, NK cell function is gradually inactivated with age. Therefore, this study used senescence as an entry point to investigate how NK cells affect AD.

Methods

The study validated the correlation between cognition and aging through a prospective cohort of the National Health and Nutrition Examination Survey database. A cellular trajectory analysis of the aging population was performed using single-cell nuclear transcriptome sequencing data from patients with AD and different ages. The genome-wide association study (GWAS) cohort of AD patients was used as the outcome event, and the expression quantitative trait locus was used as an instrumental variable. Causal associations between genes and AD were analyzed by bidirectional Mendelian randomization (MR) and co-localization. Finally, clinical cohorts were constructed to validate the expression of key genes.

Results

A correlation between cognition and aging was demonstrated using 2,171 older adults over 60 years of age. Gene regulation analysis revealed that most of the highly active transcription factors were concentrated in the NK cell subpopulation of AD. NK cell trajectories were constructed for different age populations. MR and co-localization analyses revealed that CHD6 may be one of the factors influencing AD.

Conclusion

We explored different levels of AD and aging from population cohorts, single-cell data, and GWAS cohorts and found that there may be some correlations of NK cells between aging and AD. It also provides some basis for potential causation.

Correlation of Plasmatic Amyloid Beta Peptides (Aβ-40, Aβ-42) with Myocardial Injury and Inflammatory Biomarkers in Acute Coronary Syndrome

Background/Objective: Amyloid beta (β) -40 levels increase with age and inflammation states and appear to be associated with clinical manifestations of acute coronary syndrome (ACS). We investigated the correlation of Aβ peptides with myocardial injury and inflammation biomarkers in patients with or without ST elevation myocardial infarction (STEMI, NSTEMI). Methods: This singe-center, cross-sectional, observational, and correlation study included 65 patients with ACS (n = 34 STEMI, 29 males, age = 58 ± 12 years; n = 31 NSTEMI, 22 males, age = 60 ± 12 years) who were enrolled in the coronary care unit within 12 h after symptom onset from February 2022 to May 2023. Aβ peptide levels and biochemical parameters were assessed. Results: NSTEMI patients had a higher prevalence of hypertension (p = 0.039), diabetes (p = 0.043), smoking (p = 0.003), and prior myocardial infarction (p = 0.010) compared to STEMI patients. We observed a higher level of Aβ-42 in NSTEMI (p = 0.001) but no difference in Aβ-40 levels. We also found a correlation between age and NT-proBNP with both Aβ peptides (Aβ-40, Aβ-42) (p = 0.001, p = 0.002 respectively). Conclusions: Our results show that patients with NSTEMI had a higher prevalence of cardiovascular risk factors (hypertension, diabetes, smoking, and prior myocardial infarction). Considering these results, we propose that Aβ-42 can add value to risk stratification in NSTEMI patients.

miR-429-3p mediates memory decline by targeting MKP-1 to reduce surface GluA1-containing AMPA receptors in a mouse model of Alzheimer's disease

Alzheimer's disease (AD) is a leading cause of dementia in the elderly. Mitogen-activated protein kinase phosphatase 1 (MKP-1) plays a neuroprotective role in AD. However, the molecular mechanisms underlying the effects of MKP-1 on AD have not been extensively studied. MicroRNAs (miRNAs) regulate gene expression at the post-transcriptional level, thereby repressing mRNA translation. Here, we reported that the microRNA-429-3p (miR-429-3p) was significantly increased in the brain of APP23/PS45 AD model mice and N2AAPP AD model cells. We further found that miR-429-3p could downregulate MKP-1 expression by directly binding to its 3'-untranslated region (3' UTR). Inhibition of miR-429-3p by its antagomir (A-miR-429) restored the expression of MKP-1 to a control level and consequently reduced the amyloidogenic processing of APP and Aβ accumulation. More importantly, intranasal administration of A-miR-429 successfully ameliorated the deficits of hippocampal CA1 long-term potentiation and spatial learning and memory in AD model mice by suppressing extracellular signal-regulated kinase (ERK1/2)-mediated GluA1 hyperphosphorylation at Ser831 site, thereby increasing the surface expression of GluA1-containing α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors (AMPARs). Together, these results demonstrate that inhibiting miR-429-3p to upregulate MKP-1 effectively improves cognitive and synaptic functions in AD model mice, suggesting that miR-429/MKP-1 pathway may be a novel therapeutic target for AD treatment.

Amyloid beta 42 alters cardiac metabolism and impairs cardiac function in male mice with obesity

There are epidemiological associations between obesity and type 2 diabetes, cardiovascular disease and Alzheimer's disease. The role of amyloid beta 42 (Aβ42) in these diverse chronic diseases is obscure. Here we show that adipose tissue releases Aβ42, which is increased from adipose tissue of male mice with obesity and is associated with higher plasma Aβ42. Increasing circulating Aβ42 levels in male mice without obesity has no effect on systemic glucose homeostasis but has obesity-like effects on the heart, including reduced cardiac glucose clearance and impaired cardiac function. The closely related Aβ40 isoform does not have these same effects on the heart. Administration of an Aβ-neutralising antibody prevents obesity-induced cardiac dysfunction and hypertrophy. Furthermore, Aβ-neutralising antibody administration in established obesity prevents further deterioration of cardiac function. Multi-contrast transcriptomic analyses reveal that Aβ42 impacts pathways of mitochondrial metabolism and exposure of cardiomyocytes to Aβ42 inhibits mitochondrial complex I. These data reveal a role for systemic Aβ42 in the development of cardiac disease in obesity and suggest that therapeutics designed for Alzheimer's disease could be effective in combating obesity-induced heart failure.

Oxysterols in Central and Peripheral Synaptic Communication

Cholesterol is a key molecule for synaptic transmission, and both central and peripheral synapses are cholesterol rich. During intense neuronal activity, a substantial portion of synaptic cholesterol can be oxidized by either enzymatic or non-enzymatic pathways to form oxysterols, which in turn modulate the activities of neurotransmitter receptors (e.g., NMDA and adrenergic receptors), signaling molecules (nitric oxide synthases, protein kinase C, liver X receptors), and synaptic vesicle cycling involved in neurotransmitters release. 24-Hydroxycholesterol, produced by neurons in the brain, could directly affect neighboring synapses and change neurotransmission. 27-Hydroxycholesterol, which can cross the blood-brain barrier, can alter both synaptogenesis and synaptic plasticity. Increased generation of 25-hydroxycholesterol by activated microglia and macrophages could link inflammatory processes to learning and neuronal regulation. Amyloids and oxidative stress can lead to an increase in the levels of ring-oxidized sterols and some of these oxysterols (4-cholesten-3-one, 5α-cholestan-3-one, 7β-hydroxycholesterol, 7-ketocholesterol) have a high potency to disturb or modulate neurotransmission at both the presynaptic and postsynaptic levels. Overall, oxysterols could be used as "molecular prototypes" for therapeutic approaches. Analogs of 24-hydroxycholesterol (SGE-301, SGE-550, SAGE718) can be used for correction of NMDA receptor hypofunction-related states, whereas inhibitors of cholesterol 24-hydroxylase, cholestane-3β,5α,6β-triol, and cholest-4-en-3-one oxime (olesoxime) can be utilized as potential anti-epileptic drugs and (or) protectors from excitotoxicity.

Folic Acid and Folinic Acid Protect Hearts of Aging Triple-transgenic Alzheimer's Disease mice via IGF1R/PI3K/AKT and SIRT1/AMPK Pathways

Patients with Alzheimer's disease have increased risk of developing heart disease, which therefore highlights the need for strategies aiming at reducing Alzheimer's disease-related cardiovascular disease. Folic acid and folinic acid are beneficial to the heart. We aimed to investigate the benefits of folic acid and folinic acid in heart of patients with late-stage Alzheimer's disease. Twelve 16-month-old mice of triple-transgenic late-stage Alzheimer's disease were divided into three groups: Alzheimer's disease group, Alzheimer's disease + folic acid group, and Alzheimer's disease + folinic acid group. The mice were administered 12 mg/kg folic acid or folinic acid once daily via oral gavage for 3 months. In the folic acid and folinic acid treatment groups, the intercellular space was reduced, compared with the Alzheimer's disease group. TUNEL assay and western blot images showed that the number of apoptotic cells and the apoptosis-related protein expression were higher in the Alzheimer's disease group than in other two treated groups. Folic acid and folinic acid induced the IGF1R/PI3K/AKT and SIRT1/ AMPK pathways in the hearts of mice with Alzheimer's disease. Our results showed that folic acid and folinic acid treatment increased survival and SIRT1 expression to reduce apoptotic proteins in the heart. The aging mice treated with folinic acid had more IGF1R and SIRT1/AMPK axes to limit myocardial cell apoptosis. In conclusion, folic acid and folinic acid promote cardiac cell survival and prevent apoptosis to inhibit heart damage in aging mice with triple-transgenic late-stage Alzheimer's disease. In particular, folinic acid provides a better curative effect than folic acid.

Assessment of brain-derived extracellular vesicle enrichment for blood biomarker analysis in age-related neurodegenerative diseases: An international overview

INTRODUCTION

Brain-derived extracellular vesicles (BEVs) in blood allows for minimally- invasive investigations of CNS-specific markers of age-related neurodegenerative diseases (NDDs). Polymer-based EV- and immunoprecipitation (IP)-based BEV-enrichment protocols from blood have gained popularity. We systematically investigated protocol consistency across studies, and determined CNS-specificity of proteins associated with these protocols.

METHODS

NDD articles investigating BEVs in blood using polymer-based and/or IP-based BEV enrichment protocols were systematically identified, and protocols compared. Proteins used for BEV-enrichment and/or post-enrichment were assessed for CNS- and brain-cell-type- specificity; extracellular domains (ECD+); and presence in EV-databases.

RESULTS

82.1% of studies used polymer-based (ExoQuick) EV-enrichment, and 92.3% used L1CAM for IP-based BEV-enrichment. Centrifugation times differed across studies. 26.8% of 82 proteins systematically identified were CNS-specific: 50% ECD+, 77.3% were listed in EV- databases.

DISCUSSION

We identified protocol steps requiring standardization, and recommend additional CNS-specific proteins that can be used for BEV-enrichment or as BEV-biomarkers.

Amyloid-β: A potential mediator of aging-related vascular pathologies

Aging is one of the most promising risk factors for vascular diseases, however, the precise mechanisms mediating aging-related pathologies are not fully understood. Amyloid beta (Aβ), a peptide produced by the proteolytic processing of amyloid precursor protein (APP), is known as a key mediator of brain damage involved in the pathogenesis of Alzheimer's disease (AD). Recently, it was found that the accumulation of Aβ in the vascular wall is linked to a range of aging-related vascular pathologies, indicating a potential role of Aβ in the pathogenesis of aging-associated vascular diseases. In the present review, we have updated the molecular regulation of Aβ in vascular cells and tissues, summarized the relevance of the Aβ deposition with vascular aging and diseases, and the role of Aβ dysregulation in aging-associated vascular pathologies, including the impaired vascular response, endothelial dysfunction, oxidative stress, and inflammation. This review will provide advanced information in understanding aging-related vascular pathologies and a new avenue to explore therapeutic targets.

Gamma secretase activating protein promotes end-organ dysfunction after bacterial pneumonia

Pneumonia elicits the production of cytotoxic beta amyloid (Aβ) that contributes to end-organ dysfunction, yet the mechanism(s) linking infection to activation of the amyloidogenic pathway that produces cytotoxic Aβ is unknown. Here, we tested the hypothesis that gamma-secretase activating protein (GSAP), which contributes to the amyloidogenic pathway in the brain, promotes end-organ dysfunction following bacterial pneumonia. First-in-kind Gsap knockout rats were generated. Wild-type and knockout rats possessed similar body weights, organ weights, circulating blood cell counts, arterial blood gases, and cardiac indices at baseline. Intratracheal Pseudomonas aeruginosa infection caused acute lung injury and a hyperdynamic circulatory state. Whereas infection led to arterial hypoxemia in wild-type rats, the alveolar-capillary barrier integrity was preserved in Gsap knockout rats. Infection potentiated myocardial infarction following ischemia-reperfusion injury, and this potentiation was abolished in knockout rats. In the hippocampus, GSAP contributed to both pre- and postsynaptic neurotransmission, increasing the presynaptic action potential recruitment, decreasing neurotransmitter release probability, decreasing the postsynaptic response, and preventing postsynaptic hyperexcitability, resulting in greater early long-term potentiation but reduced late long-term potentiation. Infection abolished early and late long-term potentiation in wild-type rats, whereas the late long-term potentiation was partially preserved in Gsap knockout rats. Furthermore, hippocampi from knockout rats, and both the wild-type and knockout rats following infection, exhibited a GSAP-dependent increase in neurotransmitter release probability and postsynaptic hyperexcitability. These results elucidate an unappreciated role for GSAP in innate immunity and highlight the contribution of GSAP to end-organ dysfunction during infection.NEW & NOTEWORTHY Pneumonia is a common cause of end-organ dysfunction, both during and in the aftermath of infection. In particular, pneumonia is a common cause of lung injury, increased risk of myocardial infarction, and neurocognitive dysfunction, although the mechanisms responsible for such increased risk are unknown. Here, we reveal that gamma-secretase activating protein, which contributes to the amyloidogenic pathway, is important for end-organ dysfunction following infection.

Amyloid β induces cardiac dysfunction and neuro-signaling impairment in the heart of an Alzheimer's disease model

Aims

Alzheimer's disease (AD) is a complex neurodegenerative disorder characterized by cerebral amyloid β (Aβ) deposition and tau pathology. The AD-mediated degeneration of the brain neuro-signaling pathways, together with a potential peripheral amyloid accumulation, may also result in the derangement of the peripheral nervous system, culminating in detrimental effects on other organs, including the heart. However, whether and how AD pathology modulates cardiac function, neurotrophins, innervation, and amyloidosis is still unknown. Here, we report for the first time that cardiac remodeling, amyloid deposition, and neuro-signaling dysregulation occur in the heart of Tg2576 mice, a widely used model of AD and cerebral amyloidosis.

Methods ad Results

Echocardiographic analysis showed significant deterioration of left ventricle function, evidenced by a decline of both ejection fraction and fraction shortening percentage in 12-month-old Tg2576 mice compared to age-matched WT littermates. Tg2576 mice hearts exhibited an accumulation of amyloid aggregates, including Aβ, an increase in interstitial fibrosis and severe cardiac nervous system dysfunction. The transgenic mice also showed a significant decrease in cardiac nerve fiber density, including both adrenergic and regenerating nerve endings. This myocardial denervation was accompanied by a robust reduction in NGF and BDNF protein expression as well as GAP-43 expression (regenerating fibers) in both the brain and heart of Tg2576 mice. Accordingly, cardiomyocytes and neuronal cells challenged with Aβ oligomers showed significant downregulation of BDNF and GAP-43, indicating a causal effect of Aβ on the loss of cardiac neurotrophic function.

Conclusions

Overall, this study uncovers possible harmful effects of AD on the heart, revealing cardiac degeneration induced by Aβ through fibrosis and neuro-signaling pathway deregulation for the first time in Tg2576 mice. Our data suggest that AD pathology can cause deleterious effects on the heart, and the peripheral neurotrophic pathway may represent a potential therapeutic target to limit these effects.

Deconvolution of Plasma Pharmacokinetics from Dynamic Heart Imaging Data Obtained by Single Positron Emission Computed Tomography/Computed Tomography Imaging

Plasma pharmacokinetic (PK) data are required as an input function for graphical analysis of single positron emission computed tomography/computed tomography (SPECT/CT) and positron emission tomography/CT (PET/CT) data to evaluate tissue influx rate of radiotracers. Dynamic heart imaging data are often used as a surrogate of plasma PK. However, accumulation of radiolabel in the heart tissue may cause overprediction of plasma PK. Therefore, we developed a compartmental model, which involves forcing functions to describe intact and degraded radiolabeled proteins in plasma and their accumulation in heart tissue, to deconvolve plasma PK of 125I-amyloid beta 40 (125I-Aβ 40) and 125I-insulin from their dynamic heart imaging data. The three-compartment model was shown to adequately describe the plasma concentration-time profile of intact/degraded proteins and the heart radioactivity time data obtained from SPECT/CT imaging for both tracers. The model was successfully applied to deconvolve the plasma PK of both tracers from their naïve datasets of dynamic heart imaging. In agreement with our previous observations made by conventional serial plasma sampling, the deconvolved plasma PK of 125I-Aβ 40 and 125I-insulin in young mice exhibited lower area under the curve than aged mice. Further, Patlak plot parameters extracted using deconvolved plasma PK as input function successfully recapitulated age-dependent plasma-to-brain influx kinetics changes. Therefore, the compartment model developed in this study provides a novel approach to deconvolve plasma PK of radiotracers from their noninvasive dynamic heart imaging. This method facilitates the application of preclinical SPECT/PET imaging data to characterize distribution kinetics of tracers where simultaneous plasma sampling is not feasible. SIGNIFICANCE STATEMENT: Knowledge of plasma pharmacokinetics (PK) of a radiotracer is necessary to accurately estimate its plasma-to-brain influx. However, simultaneous plasma sampling during dynamic imaging procedures is not always feasible. In the current study, we developed approaches to deconvolve plasma PK from dynamic heart imaging data of two model radiotracers, 125I-amyloid beta 40 (125I-Aβ 40) and 125I-insulin. This novel method is expected to minimize the need for conducting additional plasma PK studies and allow for accurate estimation of the brain influx rate.

CCND1 Overexpression in Idiopathic Dilated Cardiomyopathy: A Promising Biomarker?

Cardiomyopathy, a disorder of electrical or heart muscle function, represents a type of cardiac muscle failure and culminates in severe heart conditions. The prevalence of dilated cardiomyopathy (DCM) is higher than that of other types (hypertrophic cardiomyopathy and restrictive cardiomyopathy) and causes many deaths. Idiopathic dilated cardiomyopathy (IDCM) is a type of DCM with an unknown underlying cause. This study aims to analyze the gene network of IDCM patients to identify disease biomarkers. Data were first extracted from the Gene Expression Omnibus (GEO) dataset and normalized based on the RMA algorithm (Bioconductor package), and differentially expressed genes were identified. The gene network was mapped on the STRING website, and the data were transferred to Cytoscape software to determine the top 100 genes. In the following, several genes, including VEGFA, IGF1, APP, STAT1, CCND1, MYH10, and MYH11, were selected for clinical studies. Peripheral blood samples were taken from 14 identified IDCM patients and 14 controls. The RT-PCR results revealed no significant differences in the expression of the genes APP, MYH10, and MYH11 between the two groups. By contrast, the STAT1, IGF1, CCND1, and VEGFA genes were overexpressed in patients more than in controls. The highest expression was found for VEGFA, followed by CCND1 (p < 0.001). Overexpression of these genes may contribute to disease progression in patients with IDCM. However, more patients and genes need to be analyzed in order to achieve more robust results.

The electrophysiological and neuropathological profiles of cerebellum in APPswe /PS1ΔE9 mice: A hypothesis on the role of cerebellum in Alzheimer's disease

We propose the hypothesis that the cerebellar electrophysiology and sleep-wake cycles may be altered at the early stage of Alzheimer's disease (AD), proceeding the amyloid-β neuropathological hallmarks. The electrophysiologic characteristics of cerebellum thereby might be served as a biomarker in the prepathological detection of AD. Sleep disturbances are common in preclinical AD patients, and the cerebellum has been implicated in sleep-wake regulation by several pioneer studies. Additionally, recent studies suggest that the structure and function of the cerebellum may be altered at the early stages of AD, indicating that the cerebellum may be involved in the disease's progression. We used APPswe /PS1ΔE9 mice as a model of AD, monitored and analyzed electroencephalogram data, and assessed neuropathological profiles in the cerebellum of AD mice. Our hypothesis may establish a linkage between the cerebellum and AD, thereby potentially providing new perspectives on the pathogenesis of the disease.

Mendelian randomization study reveals a causal relationship between coronary artery disease and cognitive impairment

Background

Growing evidence suggests that Coronary artery disease (CAD) is associated with cognitive impairment. However, these results from observational studies was not entirely consistent, with some detecting no such association. And it is necessary to explore the causal relationship between CAD and cognitive impairment.

Objective

We aimed to explore the potential causal relationship between CAD and cognitive impairment by using bidirectional two-sample mendelian randomization (MR) analyses.

Methods

Instrument variants were extracted according to strict selection criteria. And we used publicly available summary-level GWAS data. Five different methods of MR [random-effect inverse-variance weighted (IVW), MR Egger, weighted median, weighted mode and Wald ratio] were used to explore the causal relationship between CAD and cognitive impairment.

Results

There was little evidence to support a causal effect of CAD on cognitive impairment in the forward MR analysis. In the reverse MR analyses, We detect causal effects of fluid intelligence score (IVW: β = -0.12, 95% CI of -0.18 to -0.06, P = 6.8 × 10^-5), cognitive performance (IVW: β = -0.18, 95% CI of -0.28 to -0.08, P = 5.8 × 10^-4) and dementia with lewy bodies (IVW: OR = 1.07, 95% CI of 1.04-1.10, P = 1.1 × 10^-5) on CAD.

Conclusion

This MR analysis provides evidence of a causal association between cognitive impairment and CAD. Our findings highlight the importance of screening for coronary heart disease in patients of cognitive impairment, which might provide new insight into the prevention of CAD. Moreover, our study provides clues for risk factor identification and early prediction of CAD.

Big tau aggregation disrupts microtubule tyrosination and causes myocardial diastolic dysfunction: from discovery to therapy

BACKGROUND

Amyloid plaques and neurofibrillary tangles, the molecular lesions that characterize Alzheimer's disease (AD) and other forms of dementia, are emerging as determinants of proteinopathies 'beyond the brain'. This study aims to establish tau's putative pathophysiological mechanistic roles and potential future therapeutic targeting of tau in heart failure (HF).

METHODS AND RESULTS

A mouse model of tauopathy and human myocardial and brain tissue from patients with HF, AD, and controls was employed in this study. Tau protein expression was examined together with its distribution, and in vitro tau-related pathophysiological mechanisms were identified using a variety of biochemical, imaging, and functional approaches. A novel tau-targeting immunotherapy was tested to explore tau-targeted therapeutic potential in HF. Tau is expressed in normal and diseased human hearts, in contradistinction to the current oft-cited observation that tau is expressed specifically in the brain. Notably, the main cardiac isoform is high-molecular-weight (HMW) tau (also known as big tau), and hyperphosphorylated tau segregates in aggregates in HF and AD hearts. As previously described for amyloid-beta, the tauopathy phenotype in human myocardium is of diastolic dysfunction. Perturbation in the tubulin code, specifically a loss of tyrosinated microtubules, emerged as a potential mechanism of myocardial tauopathy. Monoclonal anti-tau antibody therapy improved myocardial function and clearance of toxic aggregates in mice, supporting tau as a potential target for novel HF immunotherapy.

CONCLUSION

The study presents new mechanistic evidence and potential treatment for the brain-heart tauopathy axis in myocardial and brain degenerative diseases and ageing.

The Effects of Amyloid-β on Metabolomic Profiles of Cardiomyocytes and Coronary Endothelial Cells

BACKGROUND

An increasing number of experimental and clinical studies show a link between Alzheimer's disease and heart diseases such as heart failure, ischemic heart disease, and atrial fibrillation. However, the mechanisms underlying the potential role of amyloid-β (Aβ) in the pathogenesis of cardiac dysfunction in Alzheimer's disease remain unknown. We have recently shown the effects of Aβ 1 - 40 and Aβ 1 - 42 on cell viability and mitochondrial function in cardiomyocytes and coronary artery endothelial cells.

OBJECTIVE

In this study, we investigated the effects of Aβ 1 - 40 and Aβ 1 - 42 on the metabolism of cardiomyocytes and coronary artery endothelial cells.

METHODS

Gas chromatography-mass spectrometry was used to analyze metabolomic profiles of cardiomyocytes and coronary artery endothelial cells treated with Aβ 1 - 40 and Aβ 1 - 42. In addition, we determined mitochondrial respiration and lipid peroxidation in these cells.

RESULTS

We found that the metabolism of different amino acids was affected by Aβ 1 - 42 in each cell type, whereas the fatty acid metabolism is consistently disrupted in both types of cells. Lipid peroxidation was significantly increased, whereas mitochondrial respiration was reduced in both cell types in response to Aβ 1 - 42.

CONCLUSION

This study revealed the disruptive effects of Aβ on lipid metabolism and mitochondria function in cardiac cells.

Autonomic nervous system and cardiac neuro-signaling pathway modulation in cardiovascular disorders and Alzheimer's disease

The heart is a functional syncytium controlled by a delicate and sophisticated balance ensured by the tight coordination of its several cell subpopulations. Accordingly, cardiomyocytes together with the surrounding microenvironment participate in the heart tissue homeostasis. In the right atrium, the sinoatrial nodal cells regulate the cardiac impulse propagation through cardiomyocytes, thus ensuring the maintenance of the electric network in the heart tissue. Notably, the central nervous system (CNS) modulates the cardiac rhythm through the two limbs of the autonomic nervous system (ANS): the parasympathetic and sympathetic compartments. The autonomic nervous system exerts non-voluntary effects on different peripheral organs. The main neuromodulator of the Sympathetic Nervous System (SNS) is norepinephrine, while the principal neurotransmitter of the Parasympathetic Nervous System (PNS) is acetylcholine. Through these two main neurohormones, the ANS can gradually regulate cardiac, vascular, visceral, and glandular functions by turning on one of its two branches (adrenergic and/or cholinergic), which exert opposite effects on targeted organs. Besides these neuromodulators, the cardiac nervous system is ruled by specific neuropeptides (neurotrophic factors) that help to preserve innervation homeostasis through the myocardial layers (from epicardium to endocardium). Interestingly, the dysregulation of this neuro-signaling pathway may expose the cardiac tissue to severe disorders of different etiology and nature. Specifically, a maladaptive remodeling of the cardiac nervous system may culminate in a progressive loss of neurotrophins, thus leading to severe myocardial denervation, as observed in different cardiometabolic and neurodegenerative diseases (myocardial infarction, heart failure, Alzheimer's disease). This review analyzes the current knowledge on the pathophysiological processes involved in cardiac nervous system impairment from the perspectives of both cardiac disorders and a widely diffused and devastating neurodegenerative disorder, Alzheimer's disease, proposing a relationship between neurodegeneration, loss of neurotrophic factors, and cardiac nervous system impairment. This overview is conducive to a more comprehensive understanding of the process of cardiac neuro-signaling dysfunction, while bringing to light potential therapeutic scenarios to correct or delay the adverse cardiovascular remodeling, thus improving the cardiac prognosis and quality of life in patients with heart or neurodegenerative disorders.

Bioinformatic analysis of biological pathways in coronary heart disease and Alzheimer’s disease

Aim. Using bioinformatic tools, to perform a pathway enrichment analysis in Alzheimer’s disease and coronary heart disease (CHD).

Materials and methods. Genes contributing to susceptibility to CHD and Alzheimer’s disease were obtained from the public database DisGeNET (Database of Gene – Disease Associations). A pathway enrichment analysis was performed in the ClueGO Cytoscape plug-in (version 3.6.0) using hypergeometric distribution and the KEGG and Reactome databases.

Results. The identified genes contributing to susceptibility to Alzheimer’s disease and CHD are included in 69 common signaling pathways, grouped into the following subgroups: cell death signaling pathways (1); signaling pathways regulating immune responses (2); signaling pathways responsible for fatty acid metabolism (3); signaling pathways involved in the functioning of the nervous system (4), cardiovascular system (5), and endocrine system (6).

Conclusion. Following the performed analysis, we identified possible associations between processes involving genetic factors and their products in CHD and Alzheimer’s disease. In particular, we assumed that susceptibility genes involved in the implementation of these pathways regulate apoptosis, production of inflammatory cytokines and chemokines, lipid metabolism, β-amyloid formation, and angiogenesis.

Diminished α7 nicotinic acetylcholine receptor (α7nAChR) rescues amyloid-β induced atrial remodeling by oxi-CaMKII/MAPK/AP-1 axis-mediated mitochondrial oxidative stress

The potential coexistence of Alzheimer's disease (AD) and atrial fibrillation (AF) is increasingly common as aging-related diseases. However, little is known about mechanisms responsible for atrial remodeling in AD pathogenesis. α7 nicotinic acetylcholine receptors (α7nAChR) has been shown to have profound effects on mitochondrial oxidative stress in both organ diseases. Here, we investigate the role of α7nAChR in mediating the effects of amyloid-β (Aβ) in cultured mouse atrial cardiomyocytes (HL-1 cells) and AD model mice (APP/PS1). In vitro, apoptosis, oxidative stress and mitochondrial dysfunction induced by Aβ long-term (72h) in HL-1 cells were prevented by α-Bungarotoxin(α-BTX), an antagonist of α7nAChR. This cardioprotective effect was due to reinstating Ca²⁺ mishandling by decreasing the activation of CaMKII and MAPK signaling pathway, especially the oxidation of CaMKII (oxi-CaMKII). In vivo studies demonstrated that targeting knockdown of α7nAChR in cardiomyocytes could ameliorate AF progression in late-stage (12 months) APP/PS1 mice. Moreover, α7nAChR deficiency in cardiomyocytes attenuated APP/PS1-mutant induced atrial remodeling characterized by reducing fibrosis, atrial dilation, conduction dysfunction, and inflammatory mediator activities via suppressing oxi-CaMKII/MAPK/AP-1. Taken together, our findings suggest that diminished α7nAChR could rescue Aβ-induced atrial remodeling through oxi-CaMKII/MAPK/AP-1-mediated mitochondrial oxidative stress in atrial cells and AD mice.

Plasma Amyloid-β in Relation to Cardiac Function and Risk of Heart Failure in General Population

BACKGROUND

Amyloid-β (Aβ) may be related to cardiac function. However, there are limited data on the association of plasma Aβ with cardiac function and risk of heart failure (HF) in the general population.

OBJECTIVES

This study sought to determine the associations of plasma amyloid-β40 (Aβ40) and amyloid-β42 (Aβ42) with echocardiographic measurements of cardiac dysfunction and with incident HF in the general population.

METHODS

The study included 4,156 participants of the population-based Rotterdam Study (mean age: 71.4 years; 57.1% women), who had plasma Aβ samples collected between 2002 and 2005 and had no established dementia and HF at baseline. Multivariable linear regression models were used to explore the cross-sectional association of plasma Aβ with echocardiographic measures. Participants were followed up until December 2016. Cox proportional hazards models were used to assess the association of Aβ levels with incident HF. Models were adjusted for cardiovascular risk factors.

RESULTS

A per 1-SD increase in log-transformed plasma Aβ40 was associated with a 0.39% (95% CI: -0.68 to -0.10) lower left ventricular ejection fraction and a 0.70 g/m² (95% CI: 0.06-1.34) larger left ventricular mass indexed by body surface area. Aβ42 was not significantly associated with echocardiographic measures cross-sectionally. During follow-up (median: 10.2 years), 472 incident HF cases were identified. A per 1-SD increase in log-transformed Aβ40 was associated with a 32% greater risk of HF (HR: 1.32; 95% CI: 1.15-1.51), and the association was significant in men, but not in women. Higher plasma Aβ42 levels were associated with an increased risk of HF (HR: 1.12; 95% CI: 1.02-1.24), although the association was attenuated after further adjustment for concomitant Aβ40 (HR: 1.03; 95% CI: 0.92-1.16).

CONCLUSIONS

Higher levels of Aβ40 were associated with worse cardiac function and higher risk of new onset HF in the general population, in particular among men.

Ventricular Electrocardiographic Signatures Associated with Dementia and Plasma Alzheimer's Disease Biomarkers in Older Adults: A Population-Based Study

BACKGROUND

Evidence has emerged that altered ventricular electrocardiogram profiles are associated with dementia, but the neuropathological mechanisms underlying their associations are poorly understood.

OBJECTIVE

To investigate the interrelationships of ventricular electrocardiogram profiles with dementia and plasma Alzheimer's disease (AD) biomarkers among older adults.

METHODS

This population-based cross-sectional study included 5,153 participants (age ≥65 years; 57.3% women) living in rural communities in China; of these, 1,281 had data on plasma amyloid-β (Aβ)40, Aβ42, total-tau, and neurofilament light chain (NfL) protein. The QT, QTc, JT, JTc, QRS intervals, and QRS axis were derived from the 10-second electrocardiogram recording. The DSM-IV criteria were followed for clinical diagnosis of dementia, the NIA-AA criteria for AD, and the NINDS-AIREN criteria for vascular dementia (VaD). Data were analyzed using general linear models, multinomial logistic models, and restricted cubic splines.

RESULTS

Of the 5,153 participants, 299 (5.8%) were diagnosed with dementia, including 194 with AD and 94 with VaD. Prolonged QT, QTc, JT, and JTc intervals were significantly associated with all-cause dementia, AD, and VaD (p < 0.05). Left QRS axis deviation was significantly associated with all-cause dementia and VaD (p < 0.01). In the subsample of plasma biomarkers (n = 1,281), prolonged QT, JT, and JTc intervals were significantly associated with a lower Aβ42/Aβ40 ratio and higher plasma NfL concentrations (p < 0.05).

CONCLUSION

Alterations in ventricular repolarization and depolarization are independently associated with all-cause dementia, AD, VaD, and AD plasma biomarkers in older adults (age ≥65 years). Ventricular electrocardiogram parameters may be valuable clinical markers for dementia and the underlying AD pathologies and neurodegeneration.

Cerebral amyloid angiopathy-related cardiac injury: Focus on cardiac cell death

Cerebral amyloid angiopathy (CAA) is a kind of disease in which amyloid β (Aβ) and other amyloid protein deposits in the cerebral cortex and the small blood vessels of the brain, causing cerebrovascular and brain parenchymal damage. CAA patients are often accompanied by cardiac injury, involving Aβ, tau and transthyroxine amyloid (ATTR). Aβ is the main injury factor of CAA, which can accelerate the formation of coronary artery atherosclerosis, aortic valve osteogenesis calcification and cardiomyocytes basophilic degeneration. In the early stage of CAA (pre-stroke), the accompanying locus coeruleus (LC) amyloidosis, vasculitis and circulating Aβ will induce first hit to the heart. When the CAA progresses to an advanced stage and causes a cerebral hemorrhage, the hemorrhage leads to autonomic nervous function disturbance, catecholamine surges, and systemic inflammation reaction, which can deal the second hit to the heart. Based on the brain-heart axis, CAA and its associated cardiac injury can create a vicious cycle that accelerates the progression of each other.

Exercise Training Prevents the Loss of Wall Thickness and Lowers Expression of Alzheimer's Related Proteins in 3xTg Mouse Jejunum

Growing evidence has demonstrated the benefits of regular exercise on cardiovascular, neural, and cognitive function in humans with Alzheimer's disease (AD). However, the consequences of AD on gastrointestinal morphology and the effects of regular exercise, which plays an important role against the development of certain gastrointestinal-related diseases, are still poorly understood. Therefore, to assess the changes in intestinal structure in a mouse model of AD and the impact of exercise, 2-month-old 3xTg-AD male mice were subjected to treadmill running 5 days per week for a period of 5 months. Jejunum from 3xTg-AD mice analyzed by histochemical methods revealed significant alterations in morphology. Compared to age-matched wild-type (WT) mice, villi length and crypt depth were increased, and collagen content of jejunum was elevated in 3xTg-AD mice. Jejunum wall dimensions, expressed as total wall thickness, outer longitudinal thickness, and inner circular thickness were decreased in 3xTg-AD compared to WT. Smooth muscle actin expression in jejunal wall was decreased in 3xTg-AD. Most of these aberrations were improved with exercise. Western blot expression of cyclin dependent kinase 5 (CDK5, involved in neural cell death and hyperphosphorylation of tau), was elevated in 3xTg-AD jejunum. This was associated with a 4-fold increase in tau5 expression. Exercise prevented the increase in expression of CDK5 and tau5. Expression of caspase 3 (an apoptotic marker) was elevated in 3xTg-AD jejunum and exercise prevented this. The results of our study indicate that the abnormalities in jejunum of the 3xTg mouse model of AD were prevented with exercise training.

Apolipoprotein E Polymorphism, Cardiac Remodeling, and Heart Failure in the ARIC Study

BACKGROUND

β-Amyloid has recently been discovered in the myocardium of patients with Alzheimer's disease (AD). Whether genetic variation in apolipoprotein E (APOE) ɛ4, a common variant associated with Alzheimer's disease, is associated with incident heart failure (HF), N-terminal pro-B-type natriuretic peptide (NT-proBNP), and cardiac structure and function is unknown.

METHODS AND RESULTS

We studied 15,064 White and Black participants in the Atherosclerosis Risk in Communities, relating genotype status at visit 1 (1987-1989) to incident HF hospitalization using Cox regression. At visits 2, 4, and 5, we assessed NT-proBNP levels by genotype. At visits 3 and 5, we related Aβ peptides to incident HF. At visit 5 (2011-2013, n = 6251), we assessed the relationship of genotype with prevalent HF and echocardiographic parameters. The mean participant age was 54.7 ± 5.8 years, 45% were men, and 73% were White. At visit 5, there was no difference in prevalent HF by genotype. The APOE ε4 carriers did not have increased risk for HF hospitalization. The APOE ε4 genotype was not associated with cardiac structure and function or NT-proBNP levels. The Aβ peptides were not associated with incident HF after multivariable adjustment.

CONCLUSIONS

A genetic predisposition to Alzheimer's disease through APOE ε4 is not associated with an increased prevalence of HF, HF hospitalization, myocardial remodeling, or biochemical evidence of HF.

Associations of cognitive performance with cardiovascular magnetic resonance phenotypes in the UK Biobank

AIMS

Existing evidence suggests links between brain and cardiovascular health. We investigated associations between cognitive performance and cardiovascular magnetic resonance (CMR) phenotypes in the UK Biobank, considering a range of potential confounders.

METHODS AND RESULTS

We studied 29 763 participants with CMR and cognitive testing, specifically, fluid intelligence (FI, 13 verbal-numeric reasoning questions), and reaction time (RT, a timed pairs matching exercise); both were considered continuous variables for modelling. We included the following CMR metrics: left and right ventricular (LV and RV) volumes in end-diastole and end-systole, LV/RV ejection fractions, LV/RV stroke volumes, LV mass, and aortic distensibility. Multivariable linear regression models were used to estimate the association of each CMR measure with FI and RT, adjusting for age, sex, smoking, education, deprivation, diabetes, hypertension, high cholesterol, prior myocardial infarction, alcohol intake, and exercise level. We report standardized beta-coefficients, 95% confidence intervals, and P-values adjusted for multiple testing. In this predominantly healthy cohort (average age 63.0 ± 7.5 years), better cognitive performance (higher FI, lower RT) was associated with larger LV/RV volumes, higher LV/RV stroke volumes, greater LV mass, and greater aortic distensibility in fully adjusted models. There was some evidence of non-linearity in the relationship between FI and LV end-systolic volume, with reversal of the direction of association at very high volumes. Associations were consistent for men and women and in different ages.

CONCLUSION

Better cognitive performance is associated with CMR measures likely representing a healthier cardiovascular phenotype. These relationships remained significant after adjustment for a range of cardiometabolic, lifestyle, and demographic factors, suggesting possible involvement of alternative disease mechanisms.

Association Between Cholinesterase Inhibitors and New-Onset Heart Failure in Patients With Alzheimer's Disease: A Nationwide Propensity Score Matching Study

Background

Autonomic nervous dysfunction is a shared clinical feature in Alzheimer's disease (AD) and heart failure (HF). Cholinesterase inhibitors (ChEIs) are widely used autonomic modulators in patients with AD, but their primary preventive benefit on new-onset HF is still uncertain.

Objective

This study examined whether ChEIs have a primary preventive effect on new-onset HF in patients with AD.

Methods

This propensity score matching (PSM) study was conducted using data from the National Health Insurance Research Database of Taiwan for 1995 to 2017. Certificated patients with AD and without a history of HF were divided into ChEI (donepezil, rivastigmine, or galantamine) users or nonusers. The primary endpoint was new-onset HF, and the secondary endpoints were myocardial infarction and cardiovascular death after 10-year follow-up.

Results

After screening 16,042 patients, 7,411 patients were enrolled, of whom 668 were ChEI users and 1,336 were nonusers after 1:2 PSM. Compared with nonusers, ChEI users exhibited a significantly lower incidence of new-onset HF (HR 0.48; 95% CI 0.34–0.68, p < 0.001) and cardiovascular death (HR 0.55; 95% CI 0.37–0.82, p = 0.003) but not of myocardial infarction (HR 1.09; 95% CI 0.52–1.62, p = 0.821) after 10-year follow-up. The preventive benefit of ChEI use compared with Non-use (controls) was consistent across all exploratory subgroups without statistically significant treatment-by-subgroup interactions.

Conclusions

Prescription of ChEIs may provide a preventive benefit associated with lower incidence of new-onset HF in patients with AD after 10-year follow-up.

Beta-Amyloid Instigates Dysfunction of Mitochondria in Cardiac Cells

Alzheimer’s disease (AD) includes the formation of extracellular deposits comprising aggregated β-amyloid (Aβ) fibers associated with oxidative stress, inflammation, mitochondrial abnormalities, and neuronal loss. There is an associative link between AD and cardiac diseases; however, the mechanisms underlying the potential role of AD, particularly Aβ in cardiac cells, remain unknown. Here, we investigated the role of mitochondria in mediating the effects of Aβ_1-40 and Aβ_1-42 in cultured cardiomyocytes and primary coronary endothelial cells. Our results demonstrated that Aβ_1-40 and Aβ_1-42 are differently accumulated in cardiomyocytes and coronary endothelial cells. Aβ_1-42 had more adverse effects than Aβ_1-40 on cell viability and mitochondrial function in both types of cells. Mitochondrial and cellular ROS were significantly increased, whereas mitochondrial membrane potential and calcium retention capacity decreased in both types of cells in response to Aβ_1-42. Mitochondrial dysfunction induced by Aβ was associated with apoptosis of the cells. The effects of Aβ_1-42 on mitochondria and cell death were more evident in coronary endothelial cells. In addition, Aβ_1-40 and Aβ_1-42 significantly increased Ca²⁺ -induced swelling in mitochondria isolated from the intact rat hearts. In conclusion, this study demonstrates the toxic effects of Aβ on cell survival and mitochondria function in cardiac cells.

Effects of Alzheimer's disease of varying severity on cardiac and autonomic function

Alzheimer’s disease (AD) is one of the most common neurodegenerative diseases in the elderly. The aim of this study was to explore the effects of AD on cardiac function and autonomic nervous function, and the feasibility of electrocardiogram (ECG) in monitoring the development of AD. APP/PS1 double transgenic mice were used in the Morris water maze (MWM) experiment to evaluate the changes of cognitive ability of AD mice, then the non-invasive ECG acquisition system was used and the changes of ECG intervals and heart rate variability (HRV) were analyzed. AD mice already had cognitive dysfunction at the age of 5 months, reaching the level of mild dementia, and the degree of dementia increased with the course of disease. There were no significant changes in ECG intervals in the AD group at each month. The mean square of successive RR interval differences, percentage of intervals >6 ms different from preceding interval, and normalized high frequency power component in the AD group were decreased and low-to-high frequency power ratio and normalized low frequency power component were increased. Combined with the results of the MWM, it was shown that the regulation mechanism of sympathetic and parasympathetic nerves in mice was already imbalanced in early stage AD, which was manifested as the increase of excessive activity of sympathetic nerves and the inhibition of parasympathetic activities. Therefore, ECG-based analysis of HRV may become a means of daily monitoring of AD and provide an auxiliary basis for clinical diagnosis.

Mitochondrial aldehyde dehydrogenase (ALDH2) rescues cardiac contractile dysfunction in an APP/PS1 murine model of Alzheimer's disease via inhibition of ACSL4-dependent ferroptosis

Alzheimer's disease (AD) is associated with high incidence of cardiovascular events but the mechanism remains elusive. Our previous study reveals a tight correlation between cardiac dysfunction and low mitochondrial aldehyde dehydrogenase (ALDH2) activity in elderly AD patients. In the present study we investigated the effect of ALDH2 overexpression on cardiac function in APP/PS1 mouse model of AD. Global ALDH2 transgenic mice were crossed with APP/PS1 mutant mice to generate the ALDH2-APP/PS1 mutant mice. Cognitive function, cardiac contractile, and morphological properties were assessed. We showed that APP/PS1 mice displayed significant cognitive deficit in Morris water maze test, myocardial ultrastructural, geometric (cardiac atrophy, interstitial fibrosis) and functional (reduced fractional shortening and cardiomyocyte contraction) anomalies along with oxidative stress, apoptosis, and inflammation in myocardium. ALDH2 transgene significantly attenuated or mitigated these anomalies. We also noted the markedly elevated levels of lipid peroxidation, the essential lipid peroxidation enzyme acyl-CoA synthetase long-chain family member 4 (ACSL4), the transcriptional regulator for ACLS4 special protein 1 (SP1) and ferroptosis, evidenced by elevated NCOA4, decreased GPx4, and SLC7A11 in myocardium of APP/PS1 mutant mice; these effects were nullified by ALDH2 transgene. In cardiomyocytes isolated from WT mice and in H9C2 myoblasts in vitro, application of Aβ (20 μM) decreased cell survival, compromised cardiomyocyte contractile function, and induced lipid peroxidation; ALDH2 transgene or activator Alda-1 rescued Aβ-induced deteriorating effects. ALDH2-induced protection against Aβ-induced lipid peroxidation was mimicked by the SP1 inhibitor tolfenamic acid (TA) or the ACSL4 inhibitor triacsin C (TC), and mitigated by the lipid peroxidation inducer 5-hydroxyeicosatetraenoic acid (5-HETE) or the ferroptosis inducer erastin. These results demonstrate an essential role for ALDH2 in AD-induced cardiac anomalies through regulation of lipid peroxidation and ferroptosis.

Plasma Myeloperoxidase as a Potential Biomarker of Patient Response to Anti-Dementia Treatment in Alzheimer's Disease

BACKGROUND

Myeloperoxidase (MPO), a neutrophil-derived pro-inflammatory protein, co-localizes with amyloid-β (Aβ) plaques in Alzheimer's disease (AD). Anti-dementia treatment may facilitate efflux of Aβ and associated plaque proteins from the brain to the peripheral circulation, therefore providing potential biomarkers for the monitoring of donor response to drug treatment.

OBJECTIVE

We investigated the diagnostic utility of MPO as a biomarker of AD, and how anti-dementia treatment alters plasma MPO concentration.

METHODS

Thirty-two AD patients were recruited, and plasma collected pre-drug administration (baseline), and 1- and 6-months post-treatment. All patients received cholinesterase inhibitors (ChEIs). At baseline and 6 months, patients underwent neuropsychological assessment. Forty-nine elderly healthy individuals with normal cognitive status served as controls. Plasma MPO concentration was measured by ELISA.

RESULTS

AD drug naïve patients had similar plasma MPO concentration to their control counterparts (p > 0.05). Baseline MPO levels positively correlated with Neuropsychiatric Inventory score (r = 0.5080; p = 0.011) and carer distress (r = 0.5022; p = 0.012). Following 1-month ChEI treatment, 84.4% of AD patients exhibited increased plasma MPO levels (p < 0.001), which decreased at 6 months (p < 0.001). MPO concentration at 1 month was greatest in AD patients whose memory deteriorated during the study period (p = 0.028), and for AD patients with deterioration in Cornell assessment score (p = 0.044).

CONCLUSION

Whereas baseline MPO levels did not differentiate between healthy and AD populations, baseline MPO positively correlated with initial Neuropsychiatric Inventory evaluation. Post-treatment, transient MPO upregulation in ChEI-treated patients may reflect worse therapeutic outcome. Further studies are required to assess the potential of plasma MPO as an AD therapeutic biomarker.

Vascular Cognitive Impairment (VCI)

Vascular cognitive impairment (VCI) is predominately caused by vascular risk factors and cerebrovascular disease. VCI includes a broad spectrum of cognitive disorders, from mild cognitive impairment to vascular dementia caused by ischemic or hemorrhagic stroke, and vascular factors alone or in a combination with neurodegeneration including Alzheimer's disease (AD) and AD-related dementia. VCI accounts for at least 20-40% of all dementia diagnosis. Growing evidence indicates that cerebrovascular pathology is the most important contributor to dementia, with additive or synergistic interactions with neurodegenerative pathology. The most common underlying mechanism of VCI is chronic age-related dysregulation of CBF, although other factors such as inflammation and cardiovascular dysfunction play a role. Vascular risk factors are prevalent in VCI and if measured in midlife they predict cognitive impairment and dementia in later life. Particularly, hypertension, high cholesterol, diabetes, and smoking at midlife are each associated with a 20 to 40% increased risk of dementia. Control of these risk factors including multimodality strategies with an inclusion of lifestyle modification is the most promising strategy for treatment and prevention of VCI. In this review, we present recent developments in age-related VCI, its mechanisms, diagnostic criteria, neuroimaging correlates, vascular risk determinants, and current intervention strategies for prevention and treatment of VCI. We have also summarized the most recent and relevant literature in the field of VCI.

Do Neurotrophins Connect Neurological Disorders and Heart Diseases?

Neurotrophins (NTs) are one of the most characterized neurotrophic factor family members and consist of four members in mammals. Growing evidence suggests that there is a complex inter- and bi-directional relationship between central nervous system (CNS) disorders and cardiac dysfunction, so-called "brain-heart axis". Recent studies suggest that CNS disorders, including neurodegenerative diseases, stroke, and depression, affect cardiovascular function via various mechanisms, such as hypothalamic-pituitary-adrenal axis augmentation. Although this brain-heart axis has been well studied in humans and mice, the involvement of NT signaling in the axis has not been fully investigated. In the first half of this review, we emphasize the importance of NTs not only in the nervous system, but also in the cardiovascular system from the embryonic stage to the adult state. In the second half, we discuss the involvement of NTs in the pathogenesis of cardiovascular diseases, and then examine whether an alteration in NTs could serve as the mediator between neurological disorders and heart dysfunction. The further investigation we propose herein could contribute to finding direct evidence for the involvement of NTs in the axis and new treatment for cardiovascular diseases.

Genetic mutations of APOEε4 carriers in cardiovascular patients lead to the development of insulin resistance and risk of Alzheimer's disease

Type 2 diabetes mellitus and Alzheimer's disease (AD), both are chronic and progressive diseases. Many cardiovascular and genetic risk factors are considered responsible for the development of AD and diabetes mellitus (DM). Genetic risk factor such as apolipoprotein E (APOE) plays a critical role in the progression of AD. Specifically, APOEε4 is genetically the strongest isoform associated with neuronal insulin deficiency, altered lipid homeostasis, and metabolism, decreased glucose uptake, impaired gray matter volume, and cerebrovascular functions. In this article, we have summarized the mechanisms of cardiovascular disturbances associated with AD and DM, impact of amyloid-β aggregation, and neurofibrillary tangles formation in AD. Moreover, cardiovascular risk factors leading to insulin resistance (IR) and amyloid-β aggregation are highlighted along with the effects of APOE risk alleles on cerebral, lipid, and cholesterol metabolism leading to CVD-mediated IR. Correspondingly, the contribution of IR, genetic and cardiovascular risk factors in amyloid-β aggregation, which may lead to the late onset of AD and DM, has been also discussed. In short, IR is related to significantly lower cerebral glucose metabolism, which sequentially forecasts poorer memory performance. Hence, there will be more chances for neural glucose intolerance and impairment of cognitive function in cardiac patients, particularly APOEε4 carriers having IR. Hence, this review provides a better understanding of the corresponding crosstalk among different pathways. This will help to investigate the rational application of preventive measures against IR and cognitive dysfunction, specifically in APOEε4 carriers' cardio-metabolic patients.

The Emerging Role of Metabolism in Brain-Heart Axis: New Challenge for the Therapy and Prevention of Alzheimer Disease. May Thioredoxin Interacting Protein (TXNIP) Play a Role?

Alzheimer disease (AD) is the most frequent cause of dementia and up to now there is not an effective therapy to cure AD. In addition, AD onset occurs decades before the diagnosis, affecting the possibility to set up appropriate therapeutic strategies. For this reason, it is necessary to investigate the effects of risk factors, such as cardiovascular diseases, in promoting AD. AD shows not only brain dysfunction, but also alterations in peripheral tissues/organs. Indeed, it exists a reciprocal connection between brain and heart, where cardiovascular alterations participate to AD as well as AD seem to promote cardiovascular dysfunction. In addition, metabolic dysfunction promotes both cardiovascular diseases and AD. In this review, we summarize the pathways involved in the regulation of the brain-heart axis and the effect of metabolism on these pathways. We also present the studies showing the role of the gut microbiota on the brain-heart axis. Herein, we propose recent evidences of the function of Thioredoxin Interacting protein (TXNIP) in mediating the role of metabolism on the brain-heart axis. TXNIP is a key regulator of metabolism at both cellular and body level and it exerts also a pathological function in several cardiovascular diseases as well as in AD.

Abnormal amyloid beta metabolism in systemic abnormalities and Alzheimer's pathology: Insights and therapeutic approaches from periphery

Alzheimer's disease (AD) is an age-associated, multifactorial neurodegenerative disorder that is incurable. Despite recent success in treatments that partially improve symptomatic relief, they have failed in most clinical trials. Re-holding AD for accurate diagnosis and treatment is widely known as a challenging task. Lack of knowledge of basic molecular pathogenesis might be a possible reason for ineffective AD treatment. Historically, a majority of therapy-based studies have investigated the role of amyloid-β (Aβ peptide) in the central nervous system (CNS), whereas less is known about Aβ peptide in the periphery in AD. In this review, we provide a comprehensive summary of the current understanding of Aβ peptide metabolism (anabolism and catabolism) in the brain and periphery. We show that the abnormal metabolism of Aβ peptide is significantly linked with central-brain and peripheral abnormalities; the interaction between peripheral Aβ peptide metabolism and peripheral abnormalities affects central-brain Aβ peptide metabolism, suggesting the existence of significant communication between these two pathways of Aβ peptide metabolism. This close interaction between the central brain and periphery in abnormal Aβ peptide metabolism plays a key role in the development and progression of AD. In conclusion, we need to obtain a full understanding of the dynamic roles of Aβ peptide at the molecular level in both the brain and periphery in relation to the pathology of AD. This will not only provide new information regarding the complex disease pathology, but also offer potential new clues to improve therapeutic strategies and diagnostic biomarkers for the successful treatment of AD.

Pathophysiological pathways in patients with heart failure and atrial fibrillation

Aims

Atrial fibrillation (AF) and heart failure (HF) are two growing epidemics that frequently co-exist. We aimed to gain insights into the underlying pathophysiological pathways in HF patients with AF by comparing circulating biomarkers using pathway overrepresentation analyses.

Methods and results

From a panel of 92 biomarkers from different pathophysiological domains available in 1620 patients with HF, we first tested which biomarkers were dysregulated in patients with HF and AF (n = 648) compared with patients in sinus rhythm (n = 972). Secondly, pathway overrepresentation analyses were performed to identify biological pathways linked to higher plasma concentrations of biomarkers in patients who had HF and AF. Findings were validated in an independent HF cohort (n = 1219, 38% with AF). Patient with AF and HF were older, less often women, and less often had a history of coronary artery disease compared with those in sinus rhythm. In the index cohort, 24 biomarkers were up-regulated in patients with AF and HF. In the validation cohort, eight biomarkers were up-regulated, which all overlapped with the 24 biomarkers found in the index cohort. The strongest up-regulated biomarkers in patients with AF were spondin-1 (fold change 1.18, P = 1.33 × 10⁻¹²), insulin-like growth factor-binding protein-1 (fold change 1.32, P = 1.08 × 10⁻⁸), and insulin-like growth factor-binding protein-7 (fold change 1.33, P = 1.35 × 10⁻¹⁸). Pathway overrepresentation analyses revealed that the presence of AF was associated with activation amyloid-beta metabolic processes, amyloid-beta formation, and amyloid precursor protein catabolic processes with a remarkable consistency observed in the validation cohort.

Conclusion

In two independent cohorts of patients with HF, the presence of AF was associated with activation of three pathways related to amyloid-beta. These hypothesis-generating results warrant confirmation in future studies.