The erythropoietin-derived peptide MK-X and erythropoietin have neuroprotective effects against ischemic brain damage

Erythropoietin (EPO) has been well known as a hematopoietic cytokine over the past decades. However, recent reports have demonstrated that EPO plays a neuroprotective role in the central nervous system, and EPO has been considered as a therapeutic target in neurodegenerative diseases such as ischemic stroke. Despite the neuroprotective effect of EPO, clinical trials have shown its unexpected side effects, including undesirable proliferative effects such as erythropoiesis and tumor growth. Therefore, the development of EPO analogs that would confer neuroprotection without adverse effects has been attempted. In this study, we examined the potential of a novel EPO-based short peptide, MK-X, as a novel drug for stroke treatment in comparison with EPO. We found that MK-X administration with reperfusion dramatically reduced brain injury in an in vivo mouse model of ischemic stroke induced by middle cerebral artery occlusion, whereas EPO had little effect. Similar to EPO, MK-X efficiently ameliorated mitochondrial dysfunction followed by neuronal death caused by glutamate-induced oxidative stress in cultured neurons. Consistent with this effect, MK-X significantly decreased caspase-3 cleavage and nuclear translocation of apoptosis-inducing factor induced by glutamate. MK-X completely mimicked the effect of EPO on multiple activation of JAK2 and its downstream PI3K/AKT and ERK1/2 signaling pathways, and this signaling process was involved in the neuroprotective effect of MK-X. Furthermore, MK-X and EPO induced similar changes in the gene expression patterns under glutamate-induced excitotoxicity. Interestingly, the most significant difference between MK-X and EPO was that MK-X better penetrated into the brain across the brain-blood barrier than did EPO. In conclusion, we suggest that MK-X might be used as a novel drug for protection from brain injury caused by ischemic stroke, which penetrates into the brain faster in comparison with EPO, even though MK-X and EPO have similar protective effects against excitotoxicity.1

Refined prefrontal working memory network as a neuromarker for Alzheimer’s disease

Detecting Alzheimer’s disease (AD) is an important step in preventing pathological brain damage. Working memory (WM)-related network modulation can be a pathological feature of AD, but is usually modulated by untargeted cognitive processes and individual variance, resulting in the concealment of this key information. Therefore, in this study, we comprehensively investigated a new neuromarker, named “refined network,” in a prefrontal cortex (PFC) that revealed the pathological features of AD. A refined network was acquired by removing unnecessary variance from the WM-related network. By using a functional near-infrared spectroscopy (fNIRS) device, we evaluated the reliability of the refined network, which was identified from the three groups classified by AD progression: healthy people (N=31), mild cognitive impairment (N=11), and patients with AD (N=18). As a result, we identified edges with significant correlations between cognitive functions and groups in the dorsolateral PFC. Moreover, the refined network achieved a significantly correlating metric with neuropsychological test scores, and a remarkable three-class classification accuracy (95.0%). These results implicate the refined PFC WM-related network as a powerful neuromarker for AD screening. © 2021 Optical Society of America1

Region-specific amyloid-β accumulation in the olfactory system influences olfactory sensory neuronal dysfunction in 5xFAD mice

Background: Hyposmia in Alzheimer’s disease (AD) is a typical early symptom according to numerous previous clinical studies. Although amyloid-β (Aβ), which is one of the toxic factors upregulated early in AD, has been identified in many studies, even in the peripheral areas of the olfactory system, the pathology involving olfactory sensory neurons (OSNs) remains poorly understood. Methods: Here, we focused on peripheral olfactory sensory neurons (OSNs) and delved deeper into the direct relationship between pathophysiological and behavioral results using odorants. We also confirmed histologically the pathological changes in 3-month-old 5xFAD mouse models, which recapitulates AD pathology. We introduced a numeric scale histologically to compare physiological phenomenon and local tissue lesions regardless of the anatomical plane. Results: We observed the odorant group that the 5xFAD mice showed reduced responses to odorants. These also did not physiologically activate OSNs that propagate their axons to the ventral olfactory bulb. Interestingly, the amount of accumulated amyloid-β (Aβ) was high in the OSNs located in the olfactory epithelial ectoturbinate and the ventral olfactory bulb glomeruli. We also observed irreversible damage to the ectoturbinate of the olfactory epithelium by measuring the impaired neuronal turnover ratio from the basal cells to the matured OSNs. Conclusions: Our results showed that partial and asymmetrical accumulation of Aβ coincided with physiologically and structurally damaged areas in the peripheral olfactory system, which evoked hyporeactivity to some odorants. Taken together, partial olfactory dysfunction closely associated with peripheral OSN’s loss could be a leading cause of AD-related hyposmia, a characteristic of early AD. © 2021, The Author(s).1

Priorities for research on neuromodulatory subcortical systems in Alzheimer's disease: Position paper from the NSS PIA of ISTAART

The neuromodulatory subcortical system (NSS) nuclei are critical hubs for survival, hedonic tone, and homeostasis. Tau-associated NSS degeneration occurs early in Alzheimer's disease (AD) pathogenesis, long before the emergence of pathognomonic memory dysfunction and cortical lesions. Accumulating evidence supports the role of NSS dysfunction and degeneration in the behavioral and neuropsychiatric manifestations featured early in AD. Experimental studies even suggest that AD-associated NSS degeneration drives brain neuroinflammatory status and contributes to disease progression, including the exacerbation of cortical lesions. Given the important pathophysiologic and etiologic roles that involve the NSS in early AD stages, there is an urgent need to expand our understanding of the mechanisms underlying NSS vulnerability and more precisely detail the clinical progression of NSS changes in AD. Here, the NSS Professional Interest Area of the International Society to Advance Alzheimer's Research and Treatment highlights knowledge gaps about NSS within AD and provides recommendations for priorities specific to clinical research, biomarker development, modeling, and intervention. HIGHLIGHTS: Neuromodulatory nuclei degenerate in early Alzheimer's disease pathological stages. Alzheimer's pathophysiology is exacerbated by neuromodulatory nuclei degeneration. Neuromodulatory nuclei degeneration drives neuropsychiatric symptoms in dementia. Biomarkers of neuromodulatory integrity would be value-creating for dementia care. Neuromodulatory nuclei present strategic prospects for disease-modifying therapies

알츠하이머 병의 후각 신경계 내부 영역 특이적 수용성 베타-아밀로이드 축적에 관한 연구

Olfactory dysfunction, Alzheimer's disease, The primary olfactory pathway, Amyloid-β, Nasal dischargeAlzheimer’s disease (AD) is an incurable neurodegenerative disease, the precise cause of which remains unclear. Identifying the characteristic symptoms at the early stages of disease can provide clues to the cause of AD. Olfactory dysfunction, which is reported beginning in the mild cognitive impairment stage, is one of the most prevalent early symptoms of AD. However, precisely how the olfactory nervous system plays a role in the progression of olfactory dysfunction in AD has been overlooked. I have investigated the accumulation of soluble amyloid-β (Aβ) proteins in the primary olfactory system and the effect thereof, given that Aβ accumulation is the most typical early pathological symptom in AD patients. Considering that the primary olfactory system is the first neural component of olfactory signaling, I hypothesized that the features of the primary olfactory system may be involved in the progression of AD pathology, which may induce olfactory dysfunction in the early stages of disease. First, I identified that olfactory dysfunction result in partial anosmia early in the pathogenesis of AD. The abnormality was indicated by region-specific Aβ accumulation in the primary olfactory system. Next, I illustrated that multimodal damage using postmortem tissue from AD patients, including morphological alterations with Aβ accumulation concomitant with microgliosis and neurotransmitter deficits, was influenced by region-specific degeneration, even in the human olfactory glomerulus. Finally, based on these findings, I identified soluble Aβ from the olfactory epithelium in the nasal discharge, which could be used to predict cognitive decline in AD patients. Taken together, the results show that soluble Aβ, which accumulates in a region-specific manner in the primary olfactory nervous system, can be measured as a sign of olfactory neurodegeneration, which induces olfactory dysfunction in AD. Furthermore, I suggest that the primary olfactory nervous system can mirror and predict pathological mechanisms in the onset stage of AD.|본 논문은 알츠하이머 병의 초기에 흔히 나타나는 증상인 후각 장애의 특징과 원인에 대한 연구이다. 알츠하이머 병은 원인이 명확하지 않고 치료약이 전무하여, 병의 시작단계에서 나타나는 증상의 특징과 원인을 파악하는 것은 알츠하이머 병의 치료와 원인 규명에 단서를 제공할 수 있다. 후각 장애는 알츠하이머 발병 이전의 경도 인지 장애 단계서부터 보고되지만, 알츠하이머 병의 진행이 후각 손상에 미치는 영향과 그 특성에 대하여 후각 신경계가 어떤 역할을 하는지는 명확하지 않다. 본 논문은 수용성 베타-아밀로이드의 축적이 알츠하이머 환자에게서 관찰할 수 있는 일반적인 초기 병리학적 증상이라는 점에 착안하여 후각 신호처리의 첫번째 회로인 일차 후각 경로 내부의 베타-아밀로이드 단백질의 축적과, 그것이 후각 장애에 미치는 영향을 조사했다. 첫번째로, 후각장애가 알츠하이머 병의 초기 병리발생 단계에서 후각저하증으로 나타나는 것을 확인했다. 또한 이 증상은 일부 향에 특이적임을 관찰했다. 이러한 부분 후각 저하증은 일차 후각 신경계 내부에서 신경재생-사멸의 재구성이 활발한 영역-특이적으로 축적된 베타-아밀로이드와 연관성이 있음을 확인했다. 다음으로, 알츠하이머 병 환자 사후 조직 내부에서도 일차 후각신경계의 신경 접합부에서 영역 특이적 베타-아밀로이드의 축적과 베타-아밀로이드의 영향을 받는 마이크로글리아의 활성화 및 신경전달물질 결손을 포함한 조직 내 병변과 구조 손상을 확인했다. 더 나아가, 후각 상피에서 관찰할 수 있는 수용성 베타-아밀로이드의 존재를 바탕으로 알츠하이머 병 환자의 인지 저하를 예측할 수 있는 콧물 내 베타-아밀로이드의 유형을 확인함과 더불어 콧물 내 단백질 조성의 변화를 동정했다. 본 논문의 결과를 바탕으로 일차 후각 신경계 내부 영역 특이적으로 축적되는 수용성 베타-아밀로이드는 후각 신경계에 의존적인 신경퇴화의 징후임을 나타내며, 이는 알츠하이머 병의 후각 기능 장애를 유도한다. 더불어 일차 후각 신경계는 알츠하이머 병 시작 단계의 병리학적 기전을 반영할 수 있음을 시사한다.NI. Introduction 1 1.1 Preface 1 1.1.1 Olfaction: Alpha et Omega 1 1.2 Research background 1 1.2.1 Olfactory dysfunction in Alzheimer’s disease: early and partial deficits 1 1.2.2 Subzonal organization of the olfactory system 2 1.2.3 The olfactory glomerulus: the first synaptic interface in the primary olfactory system 6 1.2.4 Neuropathology of Alzheimer’s disease 7 1.2.5 Generation and physiology of amyloid-β protein in the nervous system 12 1.2.6 Amyloidopathy in the mouse olfactory system 13 1.2.7 Amyloidopathy in the human olfactory system 14 1.2.8 The amyloid hypothesis: a mouse model 15 1.2.9 Validation in human subjects: amyloid-β in the olfactory system 16 1.3 Research hypothesis 16 1.4 Overview of this thesis 17 II. Materials & Methods 18 2.1 Materials 18 2.1.1 Experimental animals 18 2.1.2 Human nasal discharge 18 2.1.2.1 Subject categorizing criteria 18 2.1.2.2 Nasal discharge collection 20 2.1.3 Human specimen 20 2.1.4 Antibody & Reagent 20 2.2 Methods 23 2.2.1 Animal behavioral tests 23 2.1.1.1 Morris water maze 23 2.1.1.2 Y-maze test 23 2.1.1.3 Food-seeking test 24 2.1.1.4 Odor detection (nose poke) test 25 2.2.2 Histological experiments 26 2.2.2.1 Tissue preparation 26 2.2.2.1.1 Mouse 26 2.2.2.1.2 Human 27 2.2.2.2 Immunohistochemistry 31 2.2.2.3 Immunofluorescence 31 2.2.2.3.1 Mouse 31 2.2.2.3.2 Human 32 2.2.2.4 TUNEL assay 32 2.2.2.5 DAB intensity measurement 33 2.2.2.6 Fluorescence density measurement 33 2.2.2.7 Subregional analysis of the olfactory glomerulus 34 2.2.2.7.1 Mouse 34 2.2.2.7.2 Human 34 2.2.2.8 Three-dimensional reconstruction 36 2.2.2.9 Evaluation of microglia morphology 36 2.2.3 Nasal discharge pre-treatment 37 2.2.4 Biochemical experiments 37 2.2.4.1 Immunoblot 37 2.2.4.2 Immunoprecipitation 38 2.2.4.3 BrdU assay 38 2.2.5 Olfactory sensory neuronal calcium imaging 39 2.2.5.1 Mouse preparation 39 2.2.5.2 Odor stimulation 39 2.2.5.3 Optical recording 40 2.2.5.4 Data analysis 40 2.2.6 Electron microscopy 41 2.2.7 Proteomics 42 2.2.7.1 Liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) 42 2.2.7.2 Mass spectrometry‐based quantitative proteomic analysis (TMT-LC-MS3) 44 2.2.8 Statistical analysis 45 III. Results 46 3.1 Region-specific olfactory dysfunction revealed by transgenic mouse research 46 3.1.1 hAPP-mutated transgenic mice exhibit olfactory dysfunction before se-vere cerebral dysfunction 46 3.1.2 hAPP transgenic mice exhibit high levels of Aβ oligomers in the olfactory epithelium 48 3.1.3 Aβ accumulation in specific regions of the olfactory system in the early stages of disease in Tg mice 50 3.1.4 Evidence of active amyloidosis in the olfactory sensory neurons project-ing to the ventral olfactory glomeruli in Tg mouse 52 3.1.5 hAPP/PS1-mutated Aβ overexpressing mice exhibit olfactory dysfunction before severe cerebral dysfunction 54 3.1.6 Atypical olfactory dysfunction in Tg mice 55 3.1.7 Aβ accumulation in a specific region of the olfactory system in the early stages of disease in of Tg mice 58 3.1.8 Impaired signal transduction with Aβ accumulation in the olfactory glomerulus 61 3.1.9 Region-specific structural damage by disrupted turnover of olfactory sen-sory neurons in Tg mice 73 3.2 Region-specific human olfactory neuropathology 83 3.2.1 Gross morphology of the human olfactory glomerulus in non-demented controls 83 3.2.2 Ventral region-specific alteration of the olfactory glomerulus in AD 83 3.2.3 Aβ accumulation in the ventral olfactory glomeruli in AD patients 87 3.2.4 Increased microgliosis in the ventral olfactory glomeruli in AD patients 87 3.2.5 Impaired signal transduction in the ventral olfactory glomeruli in AD pa-tients 93 3.2.6 Impaired structure of the olfactory glomerulus in AD patients 95 3.3 Identification of soluble Aβ in nasal-derived body fluid 98 3.3.1 Detection of soluble Aβ in nasal discharge in AD patients 98 3.3.2 Positive correlation between detection of soluble Aβ in human nasal dis-charge and cognitive decline in AD patients 105 3.3.3 Profiling of the high-throughput proteome in nasal discharge and associa-tion with soluble Aβ protein in AD progression 110 IV. Discussion 112 4.1 Summary 112 4.2 Olfactory dysfunction in early-stage AD 112 4.3 Features of olfactory neurodegeneration 117 4.4 Impact of region-specific Aβ accumulation in the olfactory system in AD 119 4.5 Features of β-amyloidosis in the olfactory system 123 4.6 Toxicity of oligomeric Aβ in the olfactory nervous system 124 4.7 Biomonitoring of AD progression using soluble Aβ in body fluid from the ol-factory system 127 4.8 Contributions of the olfactory system to AD research: the olfactory system, a window to the brain 131 V. Conclusion 132 5.1 Conclusion 132 References 요약문DoctordCollectio

Neuronal and glial vulnerability of the suprachiasmatic nucleus in tauopathies: evidence from human studies and animal models.

Tauopathies, a group of neurodegenerative diseases that includes Alzheimers disease, commonly lead to disturbances in sleep-wake patterns and circadian rhythm disorders. The circadian rhythm, a recurring 24-hour cycle governing human biological activity, is regulated by the hypothalamic suprachiasmatic nucleus (SCN) and endogenous transcriptional-translational feedback loops. Surprisingly, little attention has been given to investigating tauopathy-driven neuropathology in the SCN and the repercussions of SCN and circadian gene dysfunction in the human brain affected by tauopathies. This review aims to provide an overview of the current literature on the vulnerability of the SCN in tauopathies in humans. Emphasis is placed on elucidating the neuronal and glial changes contributing to the widespread disruption of the molecular circadian clock. Furthermore, this review identifies areas of knowledge requiring further investigation

Development of Alzheimer's disease biomarker using Aβ* 56 soluble oligomer in human nasal secretions

Background: Although soluble Aβ oligomer (AβO) might play a pivotal role in pathogenesis of Alzheimer's disease (AD), development of biomarker using detection of AβO might be limited due to its structural heterogeneity. Recently, we found the 56kDa soluble Aβ*56(Aβ*56) which is known to be involved in a very early sate of AD in human nasal secretion. The aim of this study is to explore diagnostic validity of Aβ*56 in nasal secretions in discriminating AD pathology. Method: A total of 28 patients (normal control (NC) = 9, amnestic mild cognitive impairment (aMCI) = 10, and AD = 9) were included in the study. They were dichotomized using 18F-Flutemetamol amyloid positron emission tomography (PET) into with and without detectable amyloid burden. Level of Aβ*56 in nasal secretions were measured using immune blotting. Group differences in nasal Aβ*56 level were analyzed and correlation between nasal Aβ*56 level and mean standardized uptake value ratio were also conducted. Result: There were no group differences in age, gender, and education. The nasal Aβ*56 level were significantly higher in aMCI and AD than NC group, but no group differences were found between aMCI and dementia. The nasal Aβ*56 level also had a positive correlation with cortical Aβ deposition on 18F-Flutemetamol PET. Conclusion: These results demonstrate that the nasal Aβ*56 level can be easily measured, and it may be utilized as a biomarker for the diagnosis of early AD including aMCI. The study also suggests that nasal Aβ*56 level may predict cortical deposition of Aβ.1

Non-Invasive Nasal Discharge Fluid and Other Body Fluid Biomarkers in Alzheimers Disease.

The key to current Alzheimers disease (AD) therapy is the early diagnosis for prompt intervention, since available treatments only slow the disease progression. Therefore, this lack of promising therapies has called for diagnostic screening tests to identify those likely to develop full-blown AD. Recent AD diagnosis guidelines incorporated core biomarker analyses into criteria, including amyloid-β (Aβ), total-tau (T-tau), and phosphorylated tau (P-tau). Though effective, the accessibility of screening tests involving conventional cerebrospinal fluid (CSF)- and blood-based analyses is often hindered by the invasiveness and high cost. In an attempt to overcome these shortcomings, biomarker profiling research using non-invasive body fluid has shown the potential to capture the pathological changes in the patients bodies. These novel non-invasive body fluid biomarkers for AD have emerged as diagnostic and pathological targets. Here, we review the potential peripheral biomarkers, including non-invasive peripheral body fluids of nasal discharge, tear, saliva, and urine for AD

Human nasal beta-amyloid 42 reflects cognition decline in Alzheimer's disease

Introduction: The key in Alzheimer's disease (AD) therapy is a timely and accurate diagnosis for prompt drug intervention. However, due to the high cost and invasiveness of conventional biomarker analyses, including brain positron emission tomography (PET) imaging and cerebrospinal fluid (CSF)-based assays, easy accessibility to these screening tests is often hindered. There is, therefore, a great need to develop a more accessible biomarker screening test using less invasive and cost-effective peripheral body fluid biomarkers. Previous studies examined the non-quantitative expression of beta-amyloid (Aβ) in normal and AD patients' nasal discharge fluid. They identified higher expression of oligomeric Aβ in AD patients, showing a correlation with cognitive decline. However, the quantitative measurements of nasal Aβ42 levels, including the full AD continuum, remain unknown. Here, we assessed whether quantified human nasal Aβ42 levels could identify patients with AD and differentiate them from non-AD patients. Methods: 161 subjects (cognitively normal (CN), n=32; preclinical, n=29; mild cognitive impairment (MCI), n=73; AD, n=27) underwent neuropsychological battery tests. Their nasal discharge samples were collected, and nasal Aβ42 levels were measured via enzyme-linked immunosorbent assay (ELISA). Results: We found that the second-highest quartile (Q3) group of nasal Aβ42 constituted the majority of patients with AD diagnosis (p=0.036). The Q3 group also outnumbered the other groups in the most cognitively impaired subjects in all three neuropsychological battery tests (p=0.023; p=0.008; p=0.037). Conclusions: Quantified nasal Aβ42 is strongly associated with cognition measurements. Nasal Aβ42 suggests the possibility for discriminating AD from non-AD. Funding Acknowledgments: Korea Health Industry Development Institute (HI18C0154) and Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2020R1A6A1A 03040516). FCOI Declarations: Non