Inflammatory Proteins in Plasma Are Associated with Severity of Alzheimer’s Disease

Markers of Alzheimer’s disease (AD) are being widely sought with a number of studies suggesting blood measures of inflammatory proteins as putative biomarkers. Here we report findings from a panel of 27 cytokines and related proteins in over 350 subjects with AD, subjects with Mild Cognitive Impairment (MCI) and elderly normal controls where we also have measures of longitudinal change in cognition and baseline neuroimaging measures of atrophy. In this study, we identify five inflammatory proteins associated with evidence of atrophy on MR imaging data particularly in whole brain, ventricular and entorhinal cortex measures. In addition, we observed six analytes that showed significant change (over a period of one year) in people with fast cognitive decline compared to those with intermediate and slow decline. One of these (IL-10) was also associated with brain atrophy in AD. In conclusion, IL-10 was associated with both clinical and imaging evidence of severity of disease and might therefore have potential to act as biomarker of disease progression.     

Non-Motor Symptoms in Patients with Parkinson’s Disease – Correlations with Inflammatory Cytokines in Serum

Background

Parkinson’s Disease (PD) is the second most common neurodegenerative disorder of the central nervous system. Motor symptoms are the focus of pharmacotherapy, yet non-motor features of the disease (e.g. fatigue, mood disturbances, sleep disturbances and symptoms of anxiety) are both common and disabling for the patient. The pathophysiological mechanisms behind the non-motor symptoms in PD are yet to be untangled. The main objective of this study was to investigate associations between pro-inflammatory substances and non-motor symptoms in patients with PD.

Methods and Materials

We measured C-reactive protein, interleukin (IL)-6, soluble IL-2 receptor (sIL-2R) and tumor necrosis factor-α (TNF-α) in blood samples from PD patients (n = 86) and healthy controls (n = 40). Symptoms of fatigue, depression, anxiety and sleeping difficulties were assessed using the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT), the Hospital Anxiety and Depression Scale (HAD), and the Scales for Outcome in PD-Sleep Scale respectively.

Results

IL-6 was significantly higher in PD patients than in healthy controls. Compared to healthy controls, PD patients displayed significantly higher mean scores on HAD and lower scores on FACIT, thus indicating more severe symptoms as measured with these scales. Within the PD sample, high levels of both sIL-2R and TNF-α were significantly associated with more severe symptoms assessed by means of FACIT and HAD (depression and anxiety subscales). SIL-2-R levels were able to significantly predict FACIT and HAD scores after the effects of age, gender, anti-parkinsonian medications, and severity of motor symptoms were controlled for.

Discussion

We suggest that non-motor symptoms in PD patients, such as fatigue and depressive symptoms, might be generated via inflammatory mechanisms. This knowledge might contribute to the development of novel treatment options in PD, specifically targeting non-motor symptoms.     

Lyme Disease Associated with Alzheimer’s Disease

This case report discusses a patient with co-occurring neuroborreliosis and Alzheimer’s disease (AD). Although no claim is made for causality nor is there objective evidence that spirochetes are involved in AD, co-infection may exacerbate the symptoms of either neuroborreliosis or AD. Much is to be learned about the role of spirochetes in degenerative central nervous system disease.     

Relationship between Eating Disturbance and Dementia Severity in Patients with Alzheimer’s Disease

Background

Eating is one of the most important daily activities in managing patients with dementia. Although various eating disturbance occur as dementia progresses, to our knowledge, most of the studies focused on a part of eating disturbance such as swallowing and appetite. There have been few comprehensive studies including eating habits and food preference in patients with Alzheimer’s disease (AD). The aims of this study were to investigate almost all eating disturbance and to examine the relationship of eating disturbance to dementia stage in AD.

Methods

A total of 220 patients with AD and 30 normal elderly (NE) subjects were recruited. Eating disturbance was assessed by a comprehensive questionnaire that had been previously validated. Potential relationships between the characteristics of eating disturbance and dementia stage as classified by the Clinical Dementia Rating (CDR) were assessed.

Results

Overall, 81.4% of patients with AD showed some eating and swallowing disturbance, whereas only 26.7% of the NE subjects had such a disturbance. Even in an early stage, patients with AD had many types of eating disturbance; “Appetite change” was shown in nearly half of the mild AD patients (49.5%). In the moderate stage, the scores of “change of eating habits and food preference” were highest, and in the severe stage “swallowing disturbance” became critical.

Conclusion

In AD, the relationship of dementia stage to eating disturbance differs according to the type of eating disturbance. The relationships between various eating disturbance and the severity of dementia should be considered.     

The Inflammatory Marker YKL-40 Is Elevated in Cerebrospinal Fluid from Patients with Alzheimer’s but Not Parkinson’s Disease or Dementia with Lewy Bodies

A major difference in the revised diagnostic criteria for Alzheimer’s disease (AD) is the incorporation of biomarkers to support a clinical diagnosis and allow the identification of preclinical AD due to AD neuropathological processes. However, AD-specific fluid biomarkers which specifically distinguish clinical AD dementia from other dementia disorders are still missing. Here we aimed to evaluate the disease-specificity of increased YKL-40 levels in cerebrospinal fluid (CSF) from AD patients with mild to moderate dementia (n = 49) versus Parkinson’s disease (PD) (n = 61) and dementia with Lewy bodies (DLB) patients (n = 36), and non-demented controls (n = 44). Second we aimed to investigate whether altered YKL-40 levels are associated with CSF levels of other inflammation-associated molecules. When correcting for age, AD patients exhibited 21.3%, 27.7% and 38.8% higher YKL-40 levels compared to non-demented controls (p = 0.0283), DLB (p = 0.0027) and PD patients (p<0.0001). The AD-associated increase in YKL-40 was not associated with CSF P-tau, T-tau or Aβ42. No relationship between increased YKL-40 and levels of the astrocytic marker glial-fibrillary acidic protein (GFAP), interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1) and interferon gamma-induced protein 10 (IP-10) could be identified. Our results confirm previous reports of an age-associated increased in CSF YKL-40 levels and further demonstrate increased CSF YKL-40 in AD patients versus non-demented controls and patients with DLB or PD. The increase in YKL-40 levels in the AD patients was unrelated to the established CSF AD biomarkers and the inflammatory markers GFAP, MCP-1, IP-10 and IL-8, proposing YKL-40 as a marker of yet to be identified AD-related pathological processes.     

Inflammatory,Apoptotic, and Survival Gene Signaling in Alzheimer’s Disease

Aging is associated with an enhanced susceptibility to brain dysfunction, loss of memory, and cognitive decline and significantly influences the quality of life for the affected individual. Recent molecular–genetic approaches have provided powerful insights into common age-related diseases that are both progressive and multifactorial, such as Alzheimer’s disease (AD), and in vitro in AD models. These investigations have uncovered consistent deficits in brain gene signaling mechanisms and neurotrophic substances known to contribute to normal brain function. Inflammatory signaling pathways involving up-regulation of cytosolic phospholipase A₂ and the arachidonic acid cycle, the depletion of the brain-essential fatty acid docosahexaenoic acid (DHA) and DHA-derived neuroprotectin D1, and changes in the expression of key proapoptotic and antiapoptotic members of the Bcl-2 gene family are thought to be major contributors to pathogenic processes in degenerating brain tissue. This review will focus on the roles of stress genes, apoptosis-related genes, and inflammation in the molecular genetics of AD with emphasis on the interactive nature of inflammatory, neurotrophic, and apoptotic signaling and will highlight areas of rapid progress in the characterization of action of DHA and neuroprotectin D1 and address important research challenges. We also attempt to integrate these molecular, genetic, and neurochemical changes with cellular pathways involved in brain aging to formulate an integrated understanding of multifactorial age-related neurologic disease and pharmacotherapeutic strategies that may be useful in the restoration of homeostatic brain function.     

Increased Levels of Antigen-Bound β-Amyloid Autoantibodies in Serum and Cerebrospinal Fluid of Alzheimer’s Disease Patients

Recent studies have suggested a protective role of physiological β-amyloid autoantibodies (Aβ-autoantibodies) in Alzheimer’s disease (AD). However, the determination of both free and dissociated Aβ-autoantibodies in serum hitherto has yielded inconsistent results regarding their function and possible biomarker value. Here we report the application of a new sandwich enzyme-linked immunosorbent assay (ELISA) for the determination of antigen-bound Aβ-autoantibodies (intact Aβ-IgG immune complexes) in serum and cerebrospinal fluid (CSF) of a total number of 112 AD patients and age- and gender-matched control subjects. Both serum and CSF levels of Aβ-IgG immune complexes were found to be significantly higher in AD patients compared to control subjects. Moreover, the levels of Aβ-IgG complexes were negatively correlated with the cognitive status across the groups, increasing with declining cognitive test performance of the subjects. Our results suggest a contribution of IgG-type autoantibodies to Aβ clearance in vivo and an increased immune response in AD, which may be associated with deficient Aβ-IgG removal. These findings may contribute to elucidating the role of Aβ-autoantibodies in AD pathophysiology and their potential application in AD diagnosis.     

Mitochondrial Disorders in Alzheimer’s Disease

Biochemistry (Moscow) - Alzheimer’s disease is the most common age-related neurodegenerative disease. Understanding of its etiology and pathogenesis is constantly expanding. Thus, the...     

Glutamate Metabolizing Enzymes in Prefrontal Cortex of Alzheimer’s Disease Patients

Amounts of glutamate metabolizing enzymes such as glutamate dehydrogenase (GDH), glutamine synthetase (GS), GS-like protein (GSLP), and phosphate-activated glutaminase (PAG) were compared in prefrontal cortex of control subjects and patients with Alzheimer disease (AD). The target proteins were quantified by ECL-Western immunoblotting in extracts from brain tissue prepared by two different techniques separating enzymes preferentially associated with cytoplasm (GDH I and II isoenzymes, GS, and partially GSLP) and membrane (GDH III, PAG, and partially GSLP) fractions. Amounts of all listed enzymes were found significantly increased in the patient group compared with controls. Some links between the measured values were observed in the control, but not in the AD patient group. The results may suggest for the pathological interruption of regulatory relations between distinct enzymes of glutamate metabolism in brain of AD patients.     

Interleukin-6 Serum Levels in Patients with Parkinson’s Disease

Several lines of evidence suggest that neuroimmune mechanisms may be involved in the neurodegenerative process of Parkinson’s disease (PD). Interleukin-6 (IL-6) is increased in the nigrostriatal region and in the cerebrospinal fluid of patients with PD. IL-6 serum level was evaluated in PD patients. The effects of levodopa treatment and disease severity on IL-6 were also studied. The IL-6 levels were similar between PD patients (treated and not treated) and controls. However, there was a negative correlation of IL-6 levels and the activities of daily living scale (P < 0.05), indicating that patients with more severe disease have higher levels of this cytokine. No correlation involving levodopa treatment and IL-6 serum level was found. The results suggest that only marginal effects of IL-6 occur on the peripheral immune system, and that the role of IL-6 and others neuroimmune factors needs to be well elucidated on PD.     

Differential Expression of Proteins in Brain Regions of Alzheimer’s Disease Patients

Alzheimer’s disease (AD), a progressive neurodegenerative disorder and the most common form of dementia and cognitive impairment is usually characterized by neuritic amyloid plaques, cerebrovascular amyloidosis and neurofibrillary tangles. In order to find out the pathological protein expression, a quantitative proteome analysis of AD hippocampus, substantia nigra and cortex was performed and the extent of protein expression variation not only in contrast to age-matched controls but also among the understudied regions was analyzed. Expression alterations of 48 proteins were observed in each region along with significant co/contra regulation of malate dehydrogenase, lactate dehydrogenase B chain, aconitate hydratase, protein NipSnap homolog 2, actin cytoplasmic 1, creatine kinase U-type and glyceraldehyde-3-phosphate dehydrogenase. These differentially expressed proteins are mainly involved in energy metabolism, cytoskeleton integration, apoptosis and several other potent cellular/molecular processes. Interaction association network analysis further confirms the close interacting relationship between the co/contra regulated differentially expressed proteins among all the three regions. Elucidation of co/contra regulation of differentially expressed proteins will be helpful to understand disease progression and functional alterations associated with AD.     

Imaging Striatal Microglial Activation in Patients with Parkinson’s Disease

This study investigated whether the second-generation translocator protein 18kDa (TSPO) radioligand, [¹⁸F]-FEPPA, could be used in neurodegenerative parkinsonian disorders as a biomarker for detecting neuroinflammation in the striatum. Neuroinflammation has been implicated as a potential mechanism for the progression of Parkinson’s disease (PD). Positron Emission Tomography (PET) radioligand targeting for TSPO allows for the quantification of neuroinflammation in vivo. Based on genotype of the rs6791 polymorphism in the TSPO gene, 16 mixed-affinity binders (MABs) (8 PD and age-matched 8 healthy controls (HCs)), 16 high-affinity binders (HABs) (8 PD and age-matched 8 HCs) and 4 low-affinity binders (LABs) (3 PD and 1 HCs) were identified. Total distribution volume (V_T) values in the striatum were derived from a two-tissue compartment model with arterial plasma as an input function. There was a significant main effect of genotype on [¹⁸F]-FEPPA V_T values in the caudate nucleus (p = 0.001) and putamen (p < 0.001), but no main effect of disease or disease x genotype interaction in either ROI. In the HAB group, the percentage difference between PD and HC was 16% in both caudate nucleus and putamen; in the MAB group, it was -8% and 3%, respectively. While this PET study showed no evidence of increased striatal TSPO expression in PD patients, the current findings provide some insights on the possible interactions between rs6791 polymorphism and neuroinflammation in PD.     

More Delusions May Be Observed in Low-Proficient Multilingual Alzheimer’s Disease Patients

Background

Language impairment and behavioral symptoms are both common phenomena in dementia patients. In this study, we investigated the behavioral symptoms in dementia patients with different language backgrounds. Through this, we aimed to propose a possible connection between language and delusion.

Methods

We recruited 21 patients with Alzheimer’s disease (AD), according to the DSM-IV and NINCDS-ADRDA criteria, from the memory clinic of the Cardinal Tien Hospital in Taipei, Taiwan. They were classified into two groups: 11 multilinguals who could speak Japanese, Taiwanese and Mandarin Chinese, and 10 bilinguals who only spoke Taiwanese and Mandarin Chinese. There were no differences between age, education, disease duration, disease severity, environment and medical care between these two groups. Comprehensive neuropsychological examinations, including Clinical Dementia Rating (CDR), Mini-Mental Status Examination (MMSE), Cognitive Abilities Screening Instrument (CASI), Verbal fluency, Chinese version of the Boston naming test (BNT) and the Behavioral Pathology in Alzheimer’s Disease Rating Scale (BEHAVE-AD), were administered.

Results

The multilingual group showed worse results on the Boston naming test. Other neuropsychological tests, including the MMSE, CASI and Verbal fluency, were not significantly different. More delusions were noted in the multilingual group. Three pairs of subjects were identified for further examination of their differences. These three cases presented the typical scenario of how language misunderstanding may cause delusions in multilingual dementia patients. Consequently, more emotion and distorted ideas may be induced in the multilinguals compared with the MMSE-matched controls.

Conclusion

Inappropriate mixing of language or conflict between cognition and emotion may cause more delusions in these multilingual patients. This reminds us that delusion is not a pure biological outcome of brain degeneration. Although the cognitive performance was not significantly different between our groups, language may still affect their delusion.     

Human Hippocampal Neurogenesis Persists in Aged Adults and Alzheimer’s Disease Patients

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Expression of Novel Alzheimer’s Disease Risk Genes in Control and Alzheimer’s Disease Brains

Late onset Alzheimer’s disease (LOAD) etiology is influenced by complex interactions between genetic and environmental risk factors. Large-scale genome wide association studies (GWAS) for LOAD have identified 10 novel risk genes: ABCA7, BIN1, CD2AP, CD33, CLU, CR1, EPHA1, MS4A6A, MS4A6E, and PICALM. We sought to measure the influence of GWAS single nucleotide polymorphisms (SNPs) and gene expression levels on clinical and pathological measures of AD in brain tissue from the parietal lobe of AD cases and age-matched, cognitively normal controls. We found that ABCA7, CD33, and CR1 expression levels were associated with clinical dementia rating (CDR), with higher expression being associated with more advanced cognitive decline. BIN1 expression levels were associated with disease progression, where higher expression was associated with a delayed age at onset. CD33, CLU, and CR1 expression levels were associated with disease status, where elevated expression levels were associated with AD. Additionally, MS4A6A expression levels were associated with Braak tangle and Braak plaque scores, with elevated expression levels being associated with more advanced brain pathology. We failed to detect an association between GWAS SNPs and gene expression levels in our brain series. The minor allele of rs3764650 in ABCA7 is associated with age at onset and disease duration, and the minor allele of rs670139 in MS4A6E was associated with Braak tangle and Braak plaque score. These findings suggest that expression of some GWAS genes, namely ABCA7, BIN1, CD33, CLU, CR1 and the MS4A family, are altered in AD brains.     

Oxidative and Inflammatory Pathways in Parkinson’s Disease

Parkinson’s disease (PD) is the second most prevalent age-related neurodegenerative disease with physiological manifestations including tremors, bradykinesia, abnormal postural reflexes, rigidity and akinesia and pathological landmarks showing losses of dopaminergic neurons in the substantia nigra. Although the etiology of PD has been intensively pursued for several decades, biochemical mechanisms and genetic and epigenetic factors leading to initiation and progression of the disease remain elusive. Environmental toxins including (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) MPTP, paraquat and rotenone have been shown to increase the risk of PD in humans. Oxidative stress remains the leading theory for explaining progression of PD. Studies with cell and animal models reveal oxidative and inflammatory properties of these toxins and their ability to activate glial cells which subsequently destroy neighboring dopaminergic neurons. This review describes pathological effects of neurotoxins on cells and signaling pathways for production of reactive oxygen species (ROS) that underline the pathophysiology of PD. Special issue article in honor of Dr. George DeVries.     

Role of RAGE in Alzheimer’s Disease

Receptor for advanced glycation end products (RAGE) is a receptor of the immunoglobulin super family that plays various important roles under physiological and pathological conditions. Compelling evidence suggests that RAGE acts as both an inflammatory intermediary and a critical inducer of oxidative stress, underlying RAGE-induced Alzheimer-like pathophysiological changes that drive the process of Alzheimer’s disease (AD). A critical role of RAGE in AD includes beta-amyloid (Aβ) production and accumulation, the formation of neurofibrillary tangles, failure of synaptic transmission, and neuronal degeneration. The steady-state level of Aβ depends on the balance between production and clearance. RAGE plays an important role in the Aβ clearance. RAGE acts as an important transporter via regulating influx of circulating Aβ into brain, whereas the efflux of brain-derived Aβ into the circulation via BBB is implemented by LRP1. RAGE could be an important contributor to Aβ generation via enhancing the activity of β- and/or γ-secretases and activating inflammatory response and oxidative stress. However, sRAGE–Aβ interactions could inhibit Aβ neurotoxicity and promote Aβ clearance from brain. Meanwhile, RAGE could be a promoting factor for the synaptic dysfunction and neuronal circuit dysfunction which are both the material structure of cognition, and the physiological and pathological basis of cognition. In addition, RAGE could be a trigger for the pathogenesis of Aβ and tau hyper-phosphorylation which both participate in the process of cognitive impairment. Preclinical and clinical studies have supported that RAGE inhibitors could be useful in the treatment of AD. Thus, an effective measure to inhibit RAGE may be a novel drug target in AD.