F2 isoprostane levels in plasma and urine do not support increased lipid peroxidation in cognitively impaired Parkinson disease patients

Assessment of Lipid Peroxidation in Alzheimer's Disease Differential Diagnosis and Prognosis

Alzheimer’s disease (AD) and other dementias are becoming increasingly common in the older population, and the number of people affected is expected to increase in a few years. Nowadays, biomarkers used in early AD diagnosis are expensive and invasive. Therefore, this research field is growing. In fact, peroxidation by-products derived from the oxidation of brain lipids (arachidonic (AA), docosahexanoic (DHA) and adrenic acid (AdA)) could be potential biomarkers, participating in the mechanisms of inflammation, neurotoxicity and cell death in AD pathology. Previous studies have shown specificity between lipid peroxidation compounds and other dementias (e.g., Lewy bodies (DLB), frontotemporal dementia (FTD)), but more research is required. Lipid peroxidation compounds (prostaglandins, isoprostanes, isofurans, neuroprostanes, neurofurans, dihomo-isoprostanes and dihomo-isofurans) were analysed by liquid chromatography and mass spectrometry in plasma samples from participants classified into a healthy group (n = 80), a mild cognitive impairment due to AD group (n = 106), a mild dementia due to AD group (n = 70), an advanced dementia due to AD group (n = 11) and a group of other non-AD dementias (n = 20). Most of these compounds showed statistically significant differences between groups (p < 0.05), showing higher levels for the healthy and non-AD groups than the AD groups. Then, a multivariate analysis was carried out on these compounds, showing good diagnosis indexes (AUC 0.77, sensitivity 81.3%, positive predictive value 81%). Moreover, evaluating AD disease prognosis, two compounds (15-F2t-IsoP and 14(RS)-14-F4t-NeuroP) and three total parameters (isoprostanes, isofurans and neurofurans) showed significant differences among groups. Some compounds derived from the oxidation of AA, DHA and AdA have demonstrated their potential use in differential AD diagnosis. Specifically, 15-F2t-IsoP, 14(RS)-14-F4t-NeuroP and the total parameters for isoprostanes, isofurans and neurofurans have shown prognostic value for AD from its earliest stages to its most severe form.

Mitochondrial calcium uniporter as a potential therapeutic strategy for Alzheimer's disease

Alzheimer's disease (AD), a neurodegenerative disorder, is the leading cause of dementia in the world whose aetiology is still unclear. AD was always related to ageing though there have been instances where people at an early age also succumb to this disease. With medical advancements, the mortality rate has significantly reduced which also makes people more prone to AD. AD is rare, yet the prominent disease has been widely studied with several hypotheses trying to understand the workings of its onset. The most recent and popular hypothesis in AD is the involvement of mitochondrial dysfunction and calcium homeostasis in the development of the disease though their exact roles are not known. With the sudden advent of the mitochondrial calcium uniporter (MCU), many previously known pathological hallmarks of AD may be better understood. Several studies have shown the effect of excess calcium in mitochondria and the influence of MCU complex in mitochondrial function. In this article, we discuss the possible involvement of MCU in AD by linking the uniporter to mitochondrial dysfunction, calcium homeostasis, reactive oxygen species, neurotransmitters and the hallmarks of AD - amyloid plaque formation and tau tangle formation.

The Role of Lipids in Parkinson's Disease

Parkinson’s disease (PD) is a neurodegenerative disease characterized by a progressive loss of dopaminergic neurons from the nigrostriatal pathway, formation of Lewy bodies, and microgliosis. During the past decades multiple cellular pathways have been associated with PD pathology (i.e., oxidative stress, endosomal-lysosomal dysfunction, endoplasmic reticulum stress, and immune response), yet disease-modifying treatments are not available. We have recently used genetic data from familial and sporadic cases in an unbiased approach to build a molecular landscape for PD, revealing lipids as central players in this disease. Here we extensively review the current knowledge concerning the involvement of various subclasses of fatty acyls, glycerolipids, glycerophospholipids, sphingolipids, sterols, and lipoproteins in PD pathogenesis. Our review corroborates a central role for most lipid classes, but the available information is fragmented, not always reproducible, and sometimes differs by sex, age or PD etiology of the patients. This hinders drawing firm conclusions about causal or associative effects of dietary lipids or defects in specific steps of lipid metabolism in PD. Future technological advances in lipidomics and additional systematic studies on lipid species from PD patient material may improve this situation and lead to a better appreciation of the significance of lipids for this devastating disease.

Proteome characterization in various biological fluids of Trypanosoma brucei gambiense-infected subjects

Human African trypanosomiasis (HAT) is a neglected tropical disease that is endemic in sub-Saharan Africa. Control of the disease has been recently improved by better screening and treatment strategies, and the disease is on the WHO list of possible elimination. However, some physiopathological aspects of the disease transmission and progression remain unclear. We propose a new proteomic approach to identify new targets and thus possible new biomarkers of the disease. We also focused our attention on fluids classically associated with HAT (serum and cerebrospinal fluid (CSF)) and on the more easily accessible biological fluids urine and saliva. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) established the proteomic profile of patients with early and late stage disease. The serum, CSF, urine and saliva of 3 uninfected controls, 3 early stage patients and 4 late stage patients were analyzed. Among proteins identified, in CSF, urine and saliva, respectively, 37, 8 and 24 proteins were differentially expressed and showed particular interest with regards to their function. The most promising proteins (Neogenin, Neuroserpin, secretogranin 2 in CSF; moesin in urine and intelectin 2 in saliva) were quantified by enzyme-linked immunosorbent assay in a confirmatory cohort of 14 uninfected controls, 23 patients with early stage disease and 43 patients with late stage disease. The potential of two proteins, neuroserpin and moesin, with the latter present in urine, were further characterized. Our results showed the potential of proteomic analysis to discover new biomarkers and provide the basis of the establishment of a new proteomic catalogue applied to HAT-infected subjects and controls. SIGNIFICANCE: Sleeping sickness, also called Human African Trypanosomiasis (HAT), is a parasitic infection caused by a parasitic protozoan, Trypanosoma brucei gambiense or T. b. rhodesiense which are transmitted via an infected tsetse fly: Glossina. For both, the haemolymphatic stage (or first stage) signs and symptoms are intermittent fever, lymphadenopathy, hepatosplenomegaly, headaches, pruritus, and for T. b. rhodesiense infection a chancre is often formed at the bite site. Meningoencephalitic stage (or second stage) occurs when parasites invade the CNS, it is characterised by neurological signs and symptoms such as altered gait, tremors, neuropathy, somnolence which can lead to coma and death if untreated. first stage of the disease is characterizing by fevers, headaches, itchiness, and joint pains and progressive lethargy corresponding to the second stage with confusion, poor coordination, numbness and trouble sleeping. Actually, diagnosing HAT requires specialized expertise and significant resources such as well-equipped health centers and qualified staff. Such resources are lacking in many endemic areas that are often in rural locales, so many individuals with HAT die before the diagnosis is established. In this study, we analysed by mass spectrometry the entire proteome of serum, CSF, urine and saliva samples from infected and non-infected Angolan individuals to define new biomarkers of the disease. This work of proteomics analysis is a preliminary stage to the characterization of the whole proteome, of these 4 biological fluids, of HAT patients. We have identified 69 new biomarkers. Five of them have been thoroughly investigated by ELISA quantification. Neuroserpine and Moesin are respectively promising new biomarkers in CSF and urine's patient for a better diagnosis.

Translational approaches to restoring mitochondrial function in Parkinson's disease

There is strong evidence of a key role for mitochondrial dysfunction in both sporadic and all forms of familial Parkinson's disease (PD). However, none of the clinical trials carried out with putative mitochondrial rescue agents have been successful. Firm establishment of a wet biomarker or a reliable readout from imaging studies detecting mitochondrial dysfunction and reflecting disease progression is also awaited. We will provide an overview of our current knowledge about mitochondrial dysfunction in PD and related drug screens. We will also summarise previously undertaken mitochondrial wet biomarker studies and relevant imaging studies with particular focus on 31P-MRI spectroscopy. We will conclude with an overview of clinical trials which tested putative mitochondrial rescue agents in PD patients.

Oxidative Stress in Neurodegenerative Diseases

The pathophysiologies of neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), and Alzheimer's disease (AD), are far from being fully explained. Oxidative stress (OS) has been proposed as one factor that plays a potential role in the pathogenesis of neurodegenerative disorders. Clinical and preclinical studies indicate that neurodegenerative diseases are characterized by higher levels of OS biomarkers and by lower levels of antioxidant defense biomarkers in the brain and peripheral tissues. In this article, we review the current knowledge regarding the involvement of OS in neurodegenerative diseases, based on clinical trials and animal studies. In addition, we analyze the effects of the drug-induced modulation of oxidative balance, and we explore pharmacotherapeutic strategies for OS reduction.

Biomarkers for dementia and mild cognitive impairment in Parkinson's disease

Cognitive decline is one of the most frequent and disabling nonmotor features of Parkinson's disease. Around 30% of patients with Parkinson's disease experience mild cognitive impairment, a well-established risk factor for the development of dementia. However, mild cognitive impairment in patients with Parkinson's disease is a heterogeneous entity that involves different types and extents of cognitive deficits. Because it is not currently known which type of mild cognitive impairment confers a higher risk of progression to dementia, it would be useful to define biomarkers that could identify these patients to better study disease progression and possible interventions. In this sense, the identification among patients with Parkinson's disease and mild cognitive impairment of biomarkers associated with dementia would allow the early detection of this process. This review summarizes studies from the past 25 years that have assessed the potential biomarkers of dementia and mild cognitive impairment in Parkinson's disease patients. Despite the potential importance, no biomarker has as yet been validated. However, features such as low levels of epidermal and insulin-like growth factors or uric acid in plasma/serum and of Aß in CSF, reduction of cerebral cholinergic innervation and metabolism measured by PET mainly in posterior areas, and hippocampal atrophy in MRI might be indicative of distinct deficits with a distinct risk of dementia in subgroups of patients. Longitudinal studies combining the existing techniques and new approaches are needed to identify patients at higher risk of dementia. © 2016 International Parkinson and Movement Disorder Society.

Detection of inflammatory biomarkers in saliva and urine: Potential in diagnosis, prevention, and treatment for chronic diseases

Inflammation is a part of the complex biological response of inflammatory cells to harmful stimuli, such as pathogens, irritants, or damaged cells. This inflammation has been linked to several chronic diseases including cancer, atherosclerosis, rheumatoid arthritis, and multiple sclerosis. Major biomarkers of inflammation include tumor necrosis factor, interleukins (IL)-1, IL-6, IL-8, chemokines, cyclooxygenase, 5-lipooxygenase, and C-reactive protein, all of which are regulated by the transcription factor nuclear factor-kappaB. Although examining inflammatory biomarkers in blood is a standard practice, its identification in saliva and/or urine is more convenient and non-invasive. In this review, we aim to (1) discuss the detection of these inflammatory biomarkers in urine and saliva; (2) advantages of using salivary and urinary inflammatory biomarkers over blood, while also weighing on the challenges and/or limitations of their use; (3) examine their role(s) in connection with diagnosis, prevention, treatment, and drug development for several chronic diseases with inflammatory consequences, including cancer; and (4) explore the use of innovative salivary and urine based biosensor strategies that may permit the testing of biomarkers quickly, reliably, and cost-effectively, in a decentralized setting.

Microextraction by Packed Sorbent (MEPS) and Solid-Phase Microextraction (SPME) as Sample Preparation Procedures for the Metabolomic Profiling of Urine

For a long time, sample preparation was unrecognized as a critical issue in the analytical methodology, thus limiting the performance that could be achieved. However, the improvement of microextraction techniques, particularly microextraction by packed sorbent (MEPS) and solid-phase microextraction (SPME), completely modified this scenario by introducing unprecedented control over this process. Urine is a biological fluid that is very interesting for metabolomics studies, allowing human health and disease characterization in a minimally invasive form. In this manuscript, we will critically review the most relevant and promising works in this field, highlighting how the metabolomic profiling of urine can be an extremely valuable tool for the early diagnosis of highly prevalent diseases, such as cardiovascular, oncologic and neurodegenerative ones.

Dietary fat intake, pesticide use, and Parkinson's disease

BACKGROUND

Dietary fat intake may modify Parkinson's disease (PD) risk directly or by altering the response to environmental neurotoxicants including pesticides.

METHODS

We conducted a case-control study of PD nested in the Agricultural Health Study (AHS), a cohort of pesticide applicators and spouses. We evaluated diet and pesticide use before diagnosis in 89 PD cases, confirmed by movement disorder specialists, or a corresponding date in 336 frequency-matched controls. Associations were evaluated using multivariate logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

In the AHS, PD was inversely associated with N-3 polyunsaturated fatty acids (PUFAs) (OR 0.4, 95% CI 0.2-0.8 for highest vs. lowest tertile) and the N-3 precursor α-linolenic acid (0.4, 0.2-0.8). In a meta-analysis of nine studies, including the present one, PD was inversely associated with α-linolenic acid (0.81, 0.68-0.96). In the AHS, associations of PD with the pesticides paraquat and rotenone were modified by fat intake. The OR for paraquat was 4.2 (1.5-12) in individuals with PUFA intake below the median but 1.2 (0.4-3.4) in those with higher intake (p-interaction = 0.10). The OR for rotenone was 5.8 (2.3-15) in those with saturated fat intake above the median but 1.5 (0.5-4.2) in those with lower intake (p-interaction = 0.02).

CONCLUSIONS

PUFA intake was consistently associated with lower PD risk, and dietary fats modified the association of PD risk with pesticide exposure. If confirmed, these findings suggest that a diet high in PUFAs and low in saturated fats might reduce risk of PD.

Oxidative damage to macromolecules in human Parkinson disease and the rotenone model

Parkinson disease (PD), the most common neurodegenerative movement disorder, is associated with selective degeneration of nigrostriatal dopamine neurons. Although the underlying mechanisms contributing to neurodegeneration in PD seem to be multifactorial, mitochondrial impairment and oxidative stress are widely considered to be central to many forms of the disease. Whether oxidative stress is a cause or a consequence of dopaminergic death, there is substantial evidence for oxidative stress both in human PD patients and in animal models of PD, especially using rotenone, a complex I inhibitor. There are many indices of oxidative stress, but this review covers the recent evidence for oxidative damage to nucleic acids, lipids, and proteins in both the brain and the peripheral tissues in human PD and in the rotenone model. Limitations of the existing literature and future perspectives are discussed. Understanding how each particular macromolecule is damaged by oxidative stress and the interplay of secondary damage to other biomolecules may help us design better targets for the treatment of PD.

Blood-based protein biomarkers for diagnosis and classification of neurodegenerative diseases: current progress and clinical potential

Biomarker research is a rapidly advancing field in medicine. Recent advances in genomic, genetic, epigenetic, neuroscientific, proteomic, and metabolomic knowledge and technologies have opened the way to thriving research. In the most general sense, a biomarker refers to any useful characteristic that can be measured and used as an indicator of a normal biologic process, a pathogenic process, or a pharmacologic response to a therapeutic agent. Despite the extensive resources concentrated on this area, there are very few biomarkers currently available that qualify and are satisfactorily validated for mental disorders, and there is still a major lack of biomarkers for typifying neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease. This article provides an overview of this field of research and focuses on recent advances in biomarker research in Alzheimer's disease and Parkinson's disease.

Development of Parkinson's disease biomarkers

Parkinson's disease (PD) is the most common neurodegenerative movement disorder, affecting over 6 million people worldwide. It is anticipated that the number of affected individuals may increase significantly in the most populous nations by 2030. During the past 20 years, much progress has been made in identifying and assessing various potential clinical, biochemical, imaging and genetic biomarkers for PD. Despite the wealth of information, development of a validated biomarker for PD is still ongoing. It is hoped that reliable and well-validated biomarkers will provide critical clues to assist in the diagnosis and management of Parkinson's disease patients in the near future.

Problems associated with fluid biomarkers for Parkinson's disease

This article focuses on biochemical markers that may be used in the diagnostics of Parkinson's disease and associated disorders, and to identify early cases and stratify patients into subgroups. We present an updated account of some currently available candidate fluid biomarkers, and discuss their diagnostic performance and limitations. We also discuss some of the general problems with Parkinson's disease biomarkers and possible ways of moving forward. It may be concluded that a diagnostically useful fluid biomarker for Parkinson's disease is yet to be identified. However, some interesting candidates exist and may prove useful in the future, alone or when analyzed together in patterns.

Neurochemical biomarkers in the differential diagnosis of movement disorders

In recent years, the neurochemical analysis of neuronal proteins in cerebrospinal fluid (CSF) has become increasingly accepted for the diagnosis of neurodegenerative dementia diseases such as Alzheimer's disease and Creutzfeldt-Jakob disease. CSF surrounds the central nervous system, and in the composition of CSF proteins one finds brain-specific proteins that are prioritized from blood-derived proteins. Levels of specific CSF proteins could be very promising biomarkers for central nervous system diseases. We need the development of more easily accessible biomarkers, in the blood. In neurodegenerative diseases with and without dementia, studies on CSF and blood proteins have investigated the usefulness of biomarkers in differential diagnosis. The clinical diagnoses of Parkinson's disease, dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy, and corticobasal degeneration still rely mainly on clinical symptoms as defined by international classification criteria. In this article, we review CSF biomarkers in these movement disorders and discuss recent published reports on the neurochemical intra vitam diagnosis of neurodegenerative disorders (including recent CSF alpha-synuclein findings).

Cause and consequence: mitochondrial dysfunction initiates and propagates neuronal dysfunction, neuronal death and behavioral abnormalities in age-associated neurodegenerative diseases

Age-related neurodegenerative diseases are associated with mild impairment of oxidative metabolism and accumulation of abnormal proteins. Within the cell, the mitochondria appears to be a dominant site for initiation and propagation of disease processes. Shifts in metabolism in response to mild metabolic perturbations may decrease the threshold for irreversible injury in response to ordinarily sublethal metabolic insults. Mild impairment of metabolism accrue from and lead to increased reactive oxygen species (ROS). Increased ROS change cell signaling via post-transcriptional and transcriptional changes. The cause and consequences of mild impairment of mitochondrial metabolism is one focus of this review. Many experiments in tissues from humans support the notion that oxidative modification of the alpha-ketoglutarate dehydrogenase complex (KGDHC) compromises neuronal energy metabolism and enhances ROS production in Alzheimer's Disease (AD). These data suggest that cognitive decline in AD derives from the selective tricarboxylic acid (TCA) cycle abnormalities. By contrast in Huntington's Disease (HD), a movement disorder with cognitive features distinct form AD, complex II+III abnormalities may dominate. These distinct mitochondrial abnormalities culminate in oxidative stress, energy dysfunction, and aberrant homeostasis of cytosolic calcium. Cytosolic calcium, elevations even only transiently, leads to hyperactivity of a number of enzymes. One calcium-activated enzyme with demonstrated pathophysiological import in HD and AD is transglutaminase (TGase). TGase is a crosslinking enzymes that can modulate transcription, inactivate metabolic enzymes, and cause aggregation of critical proteins. Recent data indicate that TGase can silence expression of genes involved in compensating for metabolic stress. Altogether, our results suggest that increasing KGDHC via inhibition of TGase or via a host of other strategies to be described would be effective therapeutic approaches in age-associated neurodegenerative diseases.

Biomarkers for Parkinson's disease

With the advent of systems biological concepts there has been a surge of interest in biological factors, or biomarkers that can be measured and which allow the identification of individuals at risk. Biomarkers for Parkinson's disease have been identified which provide evidence of systemic metabolic dysregulation in this disorder. Such biomarkers can be studied in blood, serum and plasma but also in CSF and urine, and the study by Hoepken et al. in this issue has even made use of skin fibroblasts. The authors report on the induction of alpha-synuclein expression and suggest that the expression changes described might potentially allow objective PD patient diagnosis in an accessible, peripheral tissue. This mini-review aims to provide a broader perspective on PD functional genomics and seeks to illustrate in a systems biological context why the findings by Hoepken and colleagues are of clinical significance.