Oxidative damage and cytogenetic analysis in leukocytes of Parkinson's disease patients

Novel Techniques for Mapping DNA Damage and Repair in the Brain

DNA damage in the brain is influenced by endogenous processes and metabolism along with exogenous exposures. Accumulation of DNA damage in the brain can contribute to various neurological disorders, including neurodegenerative diseases and neuropsychiatric disorders. Traditional methods for assessing DNA damage in the brain, such as immunohistochemistry and mass spectrometry, have provided valuable insights but are limited by their inability to map specific DNA adducts and regional distributions within the brain or genome. Recent advancements in DNA damage detection methods offer new opportunities to address these limitations and further our understanding of DNA damage and repair in the brain. Here, we review emerging techniques offering more precise and sensitive ways to detect and quantify DNA lesions in the brain or neural cells. We highlight the advancements and applications of these techniques and discuss their potential for determining the role of DNA damage in neurological disease.

Analysis of ADORA2A, MTA1, PTGDS, PTGS2, NSF, and HNMT Gene Expression Levels in Peripheral Blood of Patients with Early Stages of Parkinson's Disease

Parkinson's disease (PD) is a common chronic, age-related neurodegenerative disease. This disease is characterized by a long prodromal period. In this context, it is important to search for the genes and mechanisms that are involved in the development of the pathological process in the earliest stages of the disease. Published data suggest that blood cells, particularly lymphocytes, may be a model for studying the processes that occur in the brain in PD. Thus, in the present work, we performed an analysis of changes in the expression of the genes ADORA2A, MTA1, PTGDS, PTGS2, NSF, and HNMT in the peripheral blood of patients with early stages of PD (stages 1 and 2 of the Hoehn-Yahr scale). We found significant and PD-specific expression changes of four genes, i.e., MTA1, PTGS2, NSF, and HNMT, in the peripheral blood of patients with early stages of PD. These genes may be associated with PD pathogenesis in the early clinical stages and can be considered as potential candidate genes for this disease. Altered expression of the ADORA2A gene in treated PD patients may indicate that this gene is involved in processes affected by antiparkinsonian therapy.

In vitro evaluation of the cytotoxic and genotoxic effects of Al and Mn in ambient concentrations detected in groundwater intended for human consumption

Environmental exposure to metals can induce cytotoxic and genotoxic effects in cells and affect the health of the exposed population. To investigate the effects of aluminum (Al) and manganese (Mn), we evaluated their cytogenotoxicity using peripheral blood mononuclear cells (PBMCs) exposed to these metals at previously quantified concentrations in groundwater intended for human consumption. The cell viability, membrane integrity, nuclear division index (NDI), oxidative stress, cell death, cell cycle, and DNA damage were analyzed in PBMCs exposed to Al (0.2, 0.6, and 0.8 mg/L) and Mn (0.1, 0.3, 1.0, and 1.5 for 48 h. We found that Al induced late apoptosis; decreased cell viability, NDI, membrane integrity; and increased DNA damage. However, no significant alterations in the early apoptosis, cell cycle, and reactive oxygen species levels were observed. In contrast, exposure to Mn altered all evaluated parameters related to cytogenotoxicity. Our data show that even concentrations allowed by the Brazilian legislation for Al and Mn in groundwater intended for human consumption cause cytotoxic and genotoxic effects in PBMCs. Therefore, in view of the results found, a comprehensive approach through in vivo investigations is needed to give robustness and validity to the results obtained, thus broadening the understanding of the impacts of metals on the health of environmentally exposed people.

Immunosenescence as a convergence pathway in neurodegeneration

Immunity refers to the body's defense mechanism to protect itself against illness or to produce antibodies against pathogens. Senescence is a cellular phenomenon that integrates a sustainable growth restriction, other phenotypic abnormalities and including a pro-inflammatory secretome. It is highly involved in regulating developmental stages, tissue homeostasis, and tumor proliferation monitoring. Contemporary experimental reports imply that abolition of senescent cells employing evolved genetic and therapeutic approaches augment the chances of survival and boosts the health span of an individual. Immunosenescence is considered as a process in which dysfunction of the immune system occurs with aging and greatly includes remodeling of lymphoid organs. This in turn causes fluctuations in the immune function of the elderly that has strict relation with the expansion of autoimmune diseases, infections, malignant tumors and neurodegenerative disorders. The interaction of the nervous and immune systems during aging is marked by bi-directional influence and mutual correlation of variations. The enhanced systemic inflammatory condition in the elderly, and the neuronal immune cell activity can be modulated by inflamm-aging and peripheral immunosenescence resulting in chronic low-grade inflammatory processes in the central Nervous system known as neuro-inflammaging. For example, glia excitation by cytokines and glia pro-inflammatory productions contribute significantly to memory injury as well as in acute systemic inflammation, which is associated with high levels of Tumor necrosis factor -α and a rise in cognitive decline. In recent years its role in the pathology of Alzheimer's disease has caught research interest to a large extent. This article reviews the connection concerning the immune and nervous systems and highlights how immunosenescence and inflamm-aging can affect neurodegenerative disorders.

Upregulated DNA Damage-Linked Biomarkers in Parkinson's Disease Model Mice

SUMMARY STATEMENT

The present study examined expression of DNA damage markers in VMAT2 Lo PD model mice. The results demonstrate there is a significant increase in these DNA damage markers mostly in the brain regions of 18- and 23-month-old model mice, indicating oxidative stress-induced DNA lesion is an important pathologic feature of this mouse model.

Mitochondria - Nucleus communication in neurodegenerative disease. Who talks first, who talks louder?

Mitochondria - nuclear coadaptation has been central to eukaryotic evolution. The dynamic dialogue between the two compartments within the context of multiorganellar interactions is critical for maintaining cellular homeostasis and directing the balance survival-death in case of cellular stress. The conceptualisation of mitochondria - nucleus communication has so far been focused on the communication from the mitochondria under stress to the nucleus and the consequent signalling responses, as well as from the nucleus to mitochondria in the context of DNA damage and repair. During ageing processes this dialogue may be better viewed as an integrated bidirectional 'talk' with feedback loops that expand beyond these two organelles depending on physiological cues. Here we explore the current views on mitochondria - nucleus dialogue and its role in maintaining cellular health with a focus on brain cells and neurodegenerative disease. Thus, we detail the transcriptional responses initiated by mitochondrial dysfunction in order to protect itself and the general cellular homeostasis. Additionally, we are reviewing the knowledge of the stress pathways initiated by DNA damage which affect mitochondria homeostasis and we add the information provided by the study of combined mitochondrial and genotoxic damage. Finally, we reflect on how each organelle may take the lead in this dialogue in an ageing context where both compartments undergo accumulation of stress and damage and where, perhaps, even the communications' mechanisms may suffer interruptions.

Neuroinflammation and Parkinson's Disease-From Neurodegeneration to Therapeutic Opportunities

Parkinson’s disease (PD) is the second most prevalent neurodegenerative disorder worldwide. Clinically, it is characterized by a progressive degeneration of dopaminergic neurons (DAn), resulting in severe motor complications. Preclinical and clinical studies have indicated that neuroinflammation can play a role in PD pathophysiology, being associated with its onset and progression. Nevertheless, several key points concerning the neuroinflammatory process in PD remain to be answered. Bearing this in mind, in the present review, we cover the impact of neuroinflammation on PD by exploring the role of inflammatory cells (i.e., microglia and astrocytes) and the interconnections between the brain and the peripheral system. Furthermore, we discuss both the innate and adaptive immune responses regarding PD pathology and explore the gut–brain axis communication and its influence on the progression of the disease.

Alterations in Proteostasis System Components in Peripheral Blood Mononuclear Cells in Parkinson Disease: Focusing on the HSP70 and p62 Levels

Parkinson disease (PD) is attributed to a proteostasis disorder mediated by α-synuclein accumulating in a specific brain region. PD manifestation is often related to extraneuronal alterations, some of which could be used as diagnostic or prognostic PD biomarkers. In this work, we studied the shifts in the expression of proteostasis-associated chaperones of the HSP70 family and autophagy-dependent p62 protein values in the peripheral blood mononuclear cells (PBMC) of mild to moderate PD patients. Although we did not detect any changes in the intracellular HSP70 protein pool in PD patients compared to non-PD controls, an increase in the transcriptional activity of the stress-associated HSPA1A/B and HSPA6 genes was observed in these cells. Basal p62 content was found to be increased in PD patients’ PBMC, similarly to the p62 level in substantia nigra neural cells in PD. Moreover, the spontaneous apoptosis level was increased among PBMC and positively correlated with the p62 intracellular level in the PD group. A combined HSPA6- and p62-based analysis among 26 PD patients and 36 age-matched non-PD controls pointed out the diagnostic significance of these markers, with intermediate sensitivity and high specificity of this combination when observing patients diagnosed with PD.

An Eu3+-functionalized metal–organic framework (Eu@Zn-MOF) for the highly sensitive detection of rotenone in serum

An Eu3+-functionalized hybrid material (Eu@Zn-MOF) is successfully prepared by the postmodification of Eu3+ ions on its free sulfonic groups. Eu@Zn-MOF can serve as a visual probe to specifically recognize and detect rotenone on the basis of fluorescence quenching effect.

Reduced Immunosenescence of Peripheral Blood T Cells in Parkinson's Disease with CMV Infection Background

Immunosenescence is a process of remodeling the immune system under the influence of chronic inflammation during aging. Parkinson’s disease (PD) is a common age-associated neurodegenerative disorder and is frequently accompanied by neuroinflammation. On the other hand, cytomegalovirus (CMV), one of the most spread infections in humans, may induce chronic inflammation which contributes to immunosenescence, differentiation and the inflation of T cells and NK cells. Currently, there is no clear understanding of immunosenescence severity in PD patients infected with CMV. In this study, we analyzed differentiation stages and immunosenescence characteristics of T cells and NK cells in 31 patients with mild and moderate PD severity, 33 age-matched and 30 young healthy donors. The PD patients were 100% CMV-seropositive compared to 76% age-matched and 73% young CMV-infected healthy donors. The proportion of effector memory T cells re-expressing CD45RA, CD57⁺CD56⁻ T cells and CD57⁺CD56⁺ T cells was significantly reduced in PD patients compared with CMV-seropositive age-matched healthy individuals. The CD57⁺CD56⁻ T cell proportion in PD patients was similar to that of CMV-seropositive young healthy donors. Thus, PD is characterized by reduced peripheral blood T cell immunosenescence, even against the background of CMV infection.

Metabolic determinants of leukocyte pathogenicity in neurological diseases

Neuroinflammatory and neurodegenerative diseases are characterized by the recruitment of circulating blood-borne innate and adaptive immune cells into the central nervous system (CNS). These leukocytes sustain the detrimental response in the CNS by releasing pro-inflammatory mediators that induce activation of local glial cells, blood-brain barrier (BBB) dysfunction, and neural cell death. However, infiltrating peripheral immune cells could also dampen CNS inflammation and support tissue repair. Recent advances in the field of immunometabolism demonstrate the importance of metabolic reprogramming for the activation and functionality of such innate and adaptive immune cell populations. In particular, an increasing body of evidence suggests that the activity of metabolites and metabolic enzymes could influence the pathogenic potential of immune cells during neuroinflammatory and neurodegenerative disorders. In this review, we discuss the role of intracellular metabolic cues in regulating leukocyte-mediated CNS damage in Alzheimer's and Parkinson's disease, multiple sclerosis and stroke, highlighting the therapeutic potential of drugs targeting metabolic pathways for the treatment of neurological diseases.

Cell Cycle Deficits in Neurodegenerative Disorders: Uncovering Molecular Mechanisms to Drive Innovative Therapeutic Development

Cell cycle dysregulation has been implicated in the pathogenesis of neurodegenerative disorders. Specialised function obligates neuronal cells to subsist in a quiescent state of cell cycle once differentiated and therefore the circumstances and mechanisms underlying aberrant cell cycle activation in post-mitotic neurons in physiological and disease conditions remains an intriguing area of research. There is a strict requirement of concurrence to cell cycle regulation for neurons to ensure intracellular biochemical conformity as well as interrelationship with other cells within neural tissues. This review deliberates on various mechanisms underlying cell cycle regulation in neuronal cells and underscores potential implications of their non-compliance in neural pathology. Recent research suggests that successful duplication of genetic material without subsequent induction of mitosis induces inherent molecular flaws that eventually assert as apoptotic changes. The consequences of anomalous cell cycle activation and subsequent apoptosis are demonstrated by the increased presence of molecular stress response and apoptotic markers. This review delineates cell cycle events under normal physiological conditions and deficits amalgamated by alterations in protein levels and signalling pathways associated with cell-division are analysed. Cell cycle regulators essentially, cyclins, CDKs, cip/kip family of inhibitors, caspases, bax and p53 have been identified to be involved in impaired cell cycle regulation and associated with neural pathology. The pharmacological modulators of cell cycle that are shown to impart protection in various animal models of neurological deficits are summarised. Greater understanding of the molecular mechanisms that are indispensable to cell cycle regulation in neurons in health and disease conditions will facilitate targeted drug development for neuroprotection.

Regulation of Protein Synthesis and Apoptosis in Lymphocytes of Parkinson Patients: The Effect of Dopaminergic Treatment

BACKGROUND

Parkinson disease (PD) is a neurodegenerative disorder characterized by progressive degeneration of the dopaminergic neurons in the substantia nigra, presumably due to increased apoptosis. In previous studies, we showed altered expression of proteins involved in mammalian target of rapamycin (mTOR) antiapoptotic and double-stranded RNA-dependent protein kinase (PKR) apoptotic pathways of translational control in experimental cellular and animal models of PD.

RESULTS

In this work, our results showed clear modifications in the expression of kinases involved in mTOR and PKR apoptosis pathways, in lymphocytes of PD patients treated or not with anti-PD treatment (levodopa), which confirmed the role played by apoptosis in the pathogenesis of this disease and the positive effect of treatment with medication on this parameter. Others proteins involved in apo-ptosis were also evaluated in lymphocytes of patients as the expression of the peripheral benzodiazepine receptor and caspase-3.

CONCLUSION

Translational control is altered in PD and hence its evaluation in peripheral blood mononuclear cells may serve as an early marker of apoptosis and indicate the efficacy of the dopaminergic treatment.

Peripheral immune biomarkers and neurodegenerative diseases: A prospective cohort study with 20 years of follow-up

OBJECTIVE

To assess the associations of several blood immune biomarkers with the future risks of amyotrophic lateral sclerosis and Parkinson disease in a prospective cohort study with 20 years of follow-up.

METHODS

The Swedish Apolipoprotein-Related Mortality Risk study is a longitudinal cohort study including 812,073 participants with repeated blood biomarker measurements between 1985 and 1996 and a follow-up until 2011. Using a Cox model, we first estimated hazard ratios of amyotrophic lateral sclerosis and Parkinson disease in relation to leukocytes, immunoglobulin G, haptoglobin, and uric acid. We further described the temporal changes of these biomarkers during the 20 years prior to the diagnosis of these diseases.

RESULTS

A total of 585 incident cases of amyotrophic lateral sclerosis and 3,769 incident cases of Parkinson disease were identified during the follow-up. Increasing concentrations of leukocytes, haptoglobin, and uric acid were associated with a lower risk of Parkinson disease. No statistically significant association was, however, noted between the studied biomarkers and amyotrophic lateral sclerosis. Parkinson disease patients appeared to have lower levels of leukocytes and haptoglobin between 20 and 10 years before diagnosis and lower levels of uric acid during the 20 years before diagnosis, compared to controls, although statistically significant differences were only noted during parts of the respective time intervals after multivariable adjustment. No clear differences were noted between patients with amyotrophic lateral sclerosis and controls.

INTERPRETATION

If verified in studies of independent populations, our findings may suggest a different role of systemic inflammation on the risk of Parkinson disease compared to amyotrophic lateral sclerosis. ANN NEUROL 2019;86:913-926.

DNA damage and repair in neuropsychiatric disorders. What do we know and what are the future perspectives?

Over the past two decades, extensive research has been done to elucidate the molecular etiology and pathophysiology of neuropsychiatric disorders. In majority of them, including Alzheimer’s disease (AD), Parkinson’s disease (PD), amyotrophic lateral sclerosis (ALS), bipolar disorder (BD), schizophrenia and major depressive disorder, increased oxidative and nitrosative stress was found. This stress is known to induce oxidative damage to biomolecules, including DNA. Accordingly, increased mitochondrial and nuclear DNA, as well as RNA damage, were observed in patients suffering from these diseases. However, recent findings indicate that the patients are characterised by impaired DNA repair pathways, which may suggest that these DNA lesions could be also a result of their insufficient repair. In the current systematic, critical review, we aim to sum up, using available literature, the knowledge about the involvement of nuclear and mitochondrial DNA damage and repair, as well as about damage to RNA in pathoetiology of neuropsychiatric disorders, i.e., AD, PD, ALS, BD, schizophrenia and major depressive disorder, as well as the usefulness of the discussed factors as being diagnostic markers and targets for new therapies. Moreover, we also underline the new directions to which future studies should head to elucidate these phenomena.

DNA Laddering to Evaluate Cytogenetic Damage in Patients with Periodontitis

Background:

Inflammatory conditions show cytogenetic damage in peripheral blood leukocytes and this can be assessed using various tests. Cytogenetic damage as observed in the peripheral blood cells, is a marker of periodontal disease. DNA laddering is a sensitive assay which evaluates the cytogenetic damage. DNA laddering is a feature that can be observed when DNA fragments, resulting from apoptotic DNA fragmentation, are visualised after separation by gel electrophoresis which results in a characteristic “ladder” pattern.

Aim:

The aim of the present study is to investigate the cytogenetic damage in different forms of periodontitis in comparison with healthy controls.

Materials and Methods:

In this cross-sectional study, 15 systemically healthy subjects with moderate to severe chronic periodontitis (CGP), 15 systemically healthy subjects with generalised aggressive periodontitis(GAP) and 15 systemically healthy control subjects were recruited. Blood samples of the patients were drawn and evaluated for the cytogenetic damage by DNA laddering.

Results:

Apoptotic DNA fragmentation was observed as a “ladder” pattern at 180-200 BP intervals in both CGP and GAP groups indicating the DNA damage, in contrast with the healthy group where the ladder pattern was not observed suggesting of the healthy DNA.

Conclusion:

The results indicated that there are cytogenetic damages in both the chronic and aggressive periodontitis groups incontrast to the healthy controls.

Micronuclei and Their Association with Infertility, Pregnancy Complications, Developmental Defects, Anaemias, Inflammation, Diabetes, Chronic Kidney Disease, Obesity, Cardiovascular Disease, Neurodegenerative Diseases and Cancer

Micronuclei (MN) are a strong cytogenetic indicator of a catastrophic change in the genetic structure and stability of a cell because they originate from either chromosome breaks or whole chromosomes that have been lost from the main nucleus during cell division. The resulting genetic abnormalities can to lead to cellular malfunction, altered gene expression and impaired regenerative capacity. Furthermore, MN are increased as a consequence of genetic defects in DNA repair, deficiency in micronutrients required for DNA replication and repair and exposure to genotoxic chemicals and ultraviolet or ionising radiation. For all of these reasons, the measurement of MN has become one of the best-established methods to measure DNA damage in humans at the cytogenetic level. This chapter is a narrative review of the current evidence for the association of increased MN frequency with developmental and degenerative diseases. In addition, important knowledge gaps are identified, and recommendations for future studies required to consolidate the evidence are provided. The great majority of published studies show a significant association of increased MN in lymphocytes and/or buccal cells with infertility, pregnancy complications, developmental defects, anaemias, inflammation, diabetes, cardiovascular disease, kidney disease, neurodegenerative diseases and cancer. However, the strongest evidence is from prospective studies showing that MN frequency in lymphocytes predicts cancer risk and cardiovascular disease mortality.

Comet assay and its use for evaluating oxidative DNA damage in some pathological states

The comet assay, or single-cell gel electrophoresis (SCGE), is a sensitive, rapid, relatively simple and inexpensive method for detecting DNA strand breaks in individual cells. It is used in a broad variety of applications and as a tool to investigate DNA damage and repair. The sensitivity and specificity of the assay are greatly enhanced if the DNA incubated with an enzyme, whichrecognizes a specific kind of DNA damage. This damage induced by oxidative stress plays a pivotal role in many diseases and in aging. This article is a critical review of the possible application of the comet assay in some pathological states in clinical practice. Most of the studies relate to evaluating the response of an organism to chemotherapy or radiotherapy with statistically significant evidence of DNA damage in patients. Other useful applications have been demonstrated for patients with heart or neurodegenerative diseases. Only a few studies have been published on the use of this method in critically ill patients, although its use would be appropriate. There are also other scenarios where the comet assay could prove to be very useful in the future, such as in predicting the likelihood of certain pathological conditions.

Inflammation, Infectious Triggers, and Parkinson's Disease

Parkinson's disease is a neurodegenerative disorder characterized by progressive loss of dopaminergic neurons of the substantia nigra pars compacta with a reduction of dopamine concentration in the striatum. The complex interaction between genetic and environmental factors seems to play a role in determining susceptibility to PD and may explain the heterogeneity observed in clinical presentations. The exact etiology is not yet clear, but different possible causes have been identified. Inflammation has been increasingly studied as part of the pathophysiology of neurodegenerative diseases, corroborating the hypothesis that the immune system may be the nexus between environmental and genetic factors, and the abnormal immune function can lead to disease. In this review we report the different aspects of inflammation and immune system in Parkinson's disease, with particular interest in the possible role played by immune dysfunctions in PD, with focus on autoimmunity and processes involving infectious agents as a trigger and alpha-synuclein protein (α-syn).

Lymphoproliferation Impairment and Oxidative Stress in Blood Cells from Early Parkinson's Disease Patients

In Parkinson’s Disease (PD), the peripheral changes in the functional capacity and redox state of immune cells has been scarcely investigated, especially in the early PD stages. Aging is a risk factor for PD, and the age-related impairment of the immune system, based on a chronic-oxidative stress situation, is involved in the rate of aging. We analyzed several functions in isolated peripheral blood neutrophils and mononuclear cells from PD stage 2 patients, and compared the results to those in healthy elderly and adult controls. Several oxidative stress and damage parameters were studied in whole blood cells. The results showed an impairment of the lymphoproliferative response in stimulated conditions in the PD patients compared with age-matched controls, who also showed typical immunosenescence in comparison with adult individuals. Higher oxidative stress and damage were observed in whole blood cells from PD patients (lower glutathione peroxidase activity, and higher oxidized glutathione and malondialdehyde contents). Our results suggest an accelerated immunosenescence in PD stage 2, and that several of the parameters studied could be appropriate peripheral biomarkers in the early stages of PD.

Review: Somatic mutations in neurodegeneration

Somatic mutations are postzygotic mutations which may lead to mosaicism, the presence of cells with genetic differences in an organism. Their role in cancer is well established, but detailed investigation in health and other diseases has only been recently possible. This has been empowered by the improvements of sequencing techniques, including single-cell sequencing, which can still be error-prone but is rapidly improving. Mosaicism appears relatively common in the human body, including the normal brain, probably arising in early development, but also potentially during ageing. In this review, we first discuss theoretical considerations and current evidence relevant to somatic mutations in the brain. We present a framework to explain how they may be integrated with current views on neurodegeneration, focusing mainly on sporadic late-onset neurodegenerative diseases (Parkinson's disease, Alzheimer's disease and amyotrophic lateral sclerosis). We review the relevant studies so far, with the first evidence emerging in Alzheimer's in particular. We also discuss the role of mosaicism in inherited neurodegenerative disorders, particularly somatic instability of tandem repeats. We summarize existing views and data to present a model whereby the time of origin and spatial distribution of relevant somatic mutations, combined with any additional risk factors, may partly determine the development and onset age of sporadic neurodegenerative diseases.

Transplanted Human Neural Precursor Cells Migrate Widely but Show no Lesion-Specific Tropism in the 6-Hydroxydopamine Rat Model of Parkinson's Disease

Parkinson's disease (PD), while primarily associated with degeneration of nigrostriatal dopamine neurons, is now increasingly recognized to have more widespread cell loss and so the most effective cell replacement therapy should target all these neuronal losses. Neural precursor cells might be ideal in this regard as in certain circumstances they have been shown to migrate widely following transplantation into the CNS. The aim of this study was to investigate whether transplanted human expanded neural precursor cells (hENPs) could migrate to sites of established or evolving pathology in the adult brain using the 6-hydroxydopamine (6-OHDA) rat model of PD. hENPs were grafted into the striatum prior to, at the same time as, or after the animals received a 6-OHDA lesion to the medial forebrain bundle. The presence of donor cells was then assessed in a distant site of cell loss (substantia nigra) or sites where cell death would not be expected (frontal cortex and globus pallidus). Donor cells were found distant from the site of implantation but the migration of these hENPs was not significantly greater in the 6-OHDA-lesioned brain and the cells did not specifically target the site of cell loss in the substantia nigra. The temporal relationship of grafting relative to the lesion, and therefore dopaminergic cell death, did not affect the migration of hENPs nor their differentiation. We conclude that while transplanted hENPs are capable of migration away from the site of implantation, they show no specific tropism for sites of ongoing or established nigral dopaminergic cell loss in this lesion model. Therefore, the use of such cells to replace the range of neurons lost in PD is likely to require a deeper understanding of the migratory cues in the damaged adult brain and some manipulation of these cells prior to transplantation.

Peripheral Biomarkers of Parkinson's Disease Progression and Pioglitazone Effects

Pioglitazone, an oral hypoglycemic agent, recently failed to show promise as a disease-modifying agent in a 44-week phase 2 placebo-controlled study in 210 Parkinson's disease (PD) subjects. We analyzed peripheral biomarkers, including leukocyte PGC-1α and target gene expression, plasma interleukin 6 (IL-6) as a marker of inflammation, and urine 8-hydroxydeoxyguanosine (8OHdG) as a marker of oxidative DNA damage. Baseline or changes from baseline in biomarker levels were not associated with the rate of progression of PD. Pioglitazone did not significantly alter biomarker levels. Other agents that more effectively target these mechanisms remain of potential interest as disease modifying therapies in PD.

DNA damage in neurodegenerative diseases

Following the observation of increased oxidative DNA damage in nuclear and mitochondrial DNA extracted from post-mortem brain regions of patients affected by neurodegenerative diseases, the last years of the previous century and the first decade of the present one have been largely dedicated to the search of markers of DNA damage in neuronal samples and peripheral tissues of patients in early, intermediate or late stages of neurodegeneration. Those studies allowed to demonstrate that oxidative DNA damage is one of the earliest detectable events in neurodegeneration, but also revealed cytogenetic damage in neurodegenerative conditions, such as for example a tendency towards chromosome 21 malsegregation in Alzheimer's disease. As it happens for many neurodegenerative risk factors the question of whether DNA damage is cause or consequence of the neurodegenerative process is still open, and probably both is true. The research interest in markers of oxidative stress was shifted, in recent years, towards the search of epigenetic biomarkers of neurodegenerative disorders, following the accumulating evidence of a substantial contribution of epigenetic mechanisms to learning, memory processes, behavioural disorders and neurodegeneration. Increasing evidence is however linking DNA damage and repair with epigenetic phenomena, thereby opening the way to a very attractive and timely research topic in neurodegenerative diseases. We will address those issues in the context of Alzheimer's disease, Parkinson's disease, and Amyotrophic Lateral Sclerosis, which represent three of the most common neurodegenerative pathologies in humans.

Genome instability biomarkers and blood micronutrient risk profiles associated with mild cognitive impairment and Alzheimer's disease

Successful maintenance of metabolic systems relating to accurate DNA replication and repair is critical for optimal lifelong human health. Should this homeostatic balance become impaired, genomic instability events can arise, compromising the integrity of the genome, which may result in gene expression and human disease. Both genome instability and micronutrient imbalance have been identified and implicated in diseases associated with accelerated ageing which potentially leads to an increased risk for the future development of clinically defined neurodegenerative disorders. Cognitive decline leading to the clinical diagnosis of mild cognitive impairment (MCI) has been shown to predict an increased risk in later life of developing Alzheimer's disease (AD). Knowledge on the impact of dietary factors in relation to MCI and AD risk is improving but incomplete; in particular the role of nutrient combinations (i.e. nutriomes) has not been thoroughly investigated. Currently, there is a need for preventative strategies as well as the identification of robust and reproducible diagnostic biomarkers that will allow identification of those individuals with increased risk for neurodegenerative diseases. Growing evidence suggests cells originating from different somatic tissues derived from individuals that have been clinically diagnosed with neurodegenerative disorders exhibit elevated frequencies of DNA damage compared to tissues of cognitively normal individuals which could be due to malnutrition. The objective of this review is to discuss current evidence and identify knowledge gaps relating to genome instability biomarkers and blood micronutrient profiles from human studies of MCI and AD that may be specific to and contribute to the increased risk of these diseases. This is a vital step in order to create research strategies for the future development of diagnostics that are indicative of dementia risk and to inform preventative therapies.

DNA damage in non-communicable diseases: A clinical and epidemiological perspective

Non-communicable diseases (NCDs) are a leading cause of death and disability, representing 63% of the total death number worldwide. A characteristic phenotype of these diseases is the accelerated aging, which is the result of phenomena such as accumulated DNA damage, telomere capping loss and subcellular irreversible/nonrepaired oxidative damage. DNA damage, mostly oxidative, plays a key role in the development of most common NCDs. The present review will gather some of the most relevant knowledge concerning the presence of DNA damage in NCDs focusing on cardiovascular diseases, diabetes, chronic obstructive pulmonary disease, and neurodegenerative disorders, and discussing a selection of papers from the most informative literature. The challenge of comorbidity and the potential offered by new systems approaches for introducing these biomarkers into the clinical decision process will be discussed. Systems Medicine platforms represent the most suitable approach to personalized medicine, enabling to identify new patterns in the pathogenesis, diagnosis and prognosis of chronic diseases.

Homocysteine Level and Mechanisms of Injury in Parkinson's Disease as Related to MTHFR, MTR, and MTHFD1 Genes Polymorphisms and L-Dopa Treatment

An elevated concentration of total homocysteine (tHcy) in plasma and cerebrospinal fluid is considered to be a risk factor for Alzheimer's disease (AD) and Parkinson's disease (PD). Homocysteine (Hcy) levels are influenced by folate concentrations and numerous genetic factors through the folate cycle, however, their role in the pathogenesis of PD remains controversial. Hcy exerts a neurotoxic action and may participate in the mechanisms of neurodegeneration, such as excitotoxicity, oxidative stress, calcium accumulation, and apoptosis. Elevated Hcy levels can lead to prooxidative activity, most probably through direct interaction with N-methyl-D-aspartate (NMDA) receptors and sensitization of dopaminergic neurons to age-related dysfunction and death. Several studies have shown that higher concentration of Hcy in PD is related to long-term administration of levodopa (L-dopa). An elevation of plasma tHcy levels can also reflect deficiencies of cofactors in remethylation of Hcy to methionine (Met) (folates and vitamin B12) and in its transsulfuration to cysteine (Cys) (vitamin B6). It is believed that the increase in the concentration of Hcy in PD can affect genetic polymorphisms of the folate metabolic pathway genes, such as MTHFR (C677T, A1298C and G1793A), MTR (A2756G), and MTHFD1 (G1958A), whose frequencies tend to increase in PD patients, as well as the reduced concentration of B vitamins. In PD, increased levels of Hcy may lead to dementia, depression and progression of the disease.

Emerging candidate biomarkers for Parkinson's disease: a review

Parkinson's disease is a chronic neurodegenerative disorder leading to progressive motor impairment affecting more than 1% of the over-65 population. In spite of considerable progress in identifying the genetic and biochemical basis of PD, to date the diagnosis remains clinical and disease-modifying therapies continue to be elusive. A cornerstone in recent PD research is the investigation of biological markers that could help in identifying at-risk population or to track disease progression and response to therapies. Although none of these parameters has been validated for routine clinical practice yet, however some biochemical candidates hold great promise for application in PD patients, especially in the early stages of disease, and it is likely that in the future the diagnosis of PD will require a combination of genetic, imaging and laboratory data. In this review we discuss the most interesting biochemical markers for PD (including the "-omics" techniques), focusing on the methodological challenges in using ex vivo blood/CSF/tissue-based biomarkers and suggesting alternative strategies to overcome the difficulties that still prevent their actual use.

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.

The impact of reactive oxygen species and genetic mitochondrial mutations in Parkinson's disease

The exact pathogenesis of Parkinson's disease (PD) is still unknown and proper mechanisms that correspond to the disease remain unidentified. It is understood that PD is age-related; as age increases, the chance of onset responds accordingly. Although there are no current means of curing PD, the understanding of reactive oxygen species (ROS) provides significant insight to possible treatments. Complex I deficiencies of the respiratory chain account for the majority of unfavorable neural apoptosis generation in PD. Dopaminergic neurons are severely damaged as a result of the deficiency. Symptoms such as inhibited cognitive ability and loss of smooth motor function are the results of such impairment. The genetic mutations of Parkinson's related proteins such as PINK1 and LRRK2 contribute to mitochondrial dysfunction which precedes ROS formation. Various pathways are inhibited by these mutations, and inevitably causing neural cell damage. Antioxidants are known to negate the damaging effects of free radical overexpression. This paper expands on the specific impact of mitochondrial genetic change and production of free radicals as well as its correlation to the neurodegeneration in Parkinson's disease.

LC/MS characterization of rotenone induced cardiolipin oxidation in human lymphocytes: implications for mitochondrial dysfunction associated with Parkinson's disease

SCOPE

Rotenone is a toxicant believed to contribute to the development of Parkinson's disease.

METHODS AND RESULTS

Using human peripheral blood lymphocytes we demonstrated that exposure to rotenone resulted in disruption of electron transport accompanied by the production of reactive oxygen species, development of apoptosis and elevation of peroxidase activity of mitochondria. Employing LC/MS-based lipidomics/oxidative lipidomics we characterized molecular species of cardiolipin (CL) and its oxidation/hydrolysis products formed early in apoptosis and associated with the rotenone-induced mitochondrial dysfunction.

CONCLUSION

The major oxidized CL species - tetra-linoleoyl-CL - underwent oxidation to yield epoxy-C18:2 and dihydroxy-C18:2 derivatives predominantly localized in sn-1 and sn-2 positions, respectively. In addition, accumulation of mono-lyso-CL species and oxygenated free C18:2 were detected in rotenone-treated lymphocytes. These oxidation/hydrolysis products may be useful for the development of new biomarkers of mitochondrial dysfunction.

Cellular and molecular mediators of neuroinflammation in the pathogenesis of Parkinson's disease

Neuroinflammation is a host-defense mechanism associated with restoration of normal structure and function of the brain and neutralization of an insult. Increasing neuropathological and biochemical evidence from the brains of individuals with Parkinson's disease (PD) provides strong evidence for activation of neuroinflammatory pathways. Microglia, the resident innate immune cells, may play a major role in the inflammatory process of the diseased brain of patients with PD. Although microglia forms the first line of defense for the neural parenchyma, uncontrolled activation of microglia may directly affect neurons by releasing various molecular mediators such as inflammatory cytokines (tumor necrosis factor-α, interleukin [IL]-6, and IL-1β), nitric oxide, prostaglandin E2, and reactive oxygen and nitrogen species. Moreover, recent studies have reported that activated microglia phagocytose not only damaged cell debris but also intact neighboring cells. This phenomenon further supports their active participation in self-enduring neuronal damage cycles. As the relationship between PD and neuroinflammation is being studied, there is a realization that both cellular and molecular mediators are most likely assisting pathological processes leading to disease progression. Here, we discuss mediators of neuroinflammation, which are known activators released from damaged parenchyma of the brain and result in neuronal degeneration in patients with PD.

Neuroimmunological processes in Parkinson's disease and their relation to α-synuclein: microglia as the referee between neuronal processes and peripheral immunity

The role of neuroinflammation and the adaptive immune system in PD (Parkinson's disease) has been the subject of intense investigation in recent years, both in animal models of parkinsonism and in post-mortem PD brains. However, how these processes relate to and modulate α-syn (α-synuclein) pathology and microglia activation is still poorly understood. Specifically, how the peripheral immune system interacts, regulates and/or is induced by neuroinflammatory processes taking place during PD is still undetermined. We present herein a comprehensive review of the features and impact that neuroinflamation has on neurodegeneration in different animal models of nigral cell death, how this neuroinflammation relates to microglia activation and the way microglia respond to α-syn in vivo. We also discuss a possible role for the peripheral immune system in animal models of parkinsonism, how these findings relate to the state of microglia activation observed in these animal models and how these findings compare with what has been observed in humans with PD. Together, the available data points to the need for development of dual therapeutic strategies that modulate microglia activation to change not only the way microglia interact with the peripheral immune system, but also to modulate the manner in which microglia respond to encounters with α-syn. Lastly, we discuss the immune-modulatory strategies currently under investigation in animal models of parkinsonism and the degree to which one might expect their outcomes to translate faithfully to a clinical setting.

The role of innate and adaptive immunity in Parkinson's disease

In recent years, inflammation has become implicated as a major pathogenic factor in the onset and progression of Parkinson's disease. Understanding the precise role for inflammation in PD will likely lead to understanding of how sporadic disease arises. In vivo evidence for inflammation in PD includes microglial activation, increased expression of inflammatory genes in the periphery and in the central nervous system (CNS), infiltration of peripheral immune cells into the CNS, and altered composition and phenotype of peripheral immune cells. These findings are recapitulated in various animal models of PD and are reviewed herein. Furthermore, we examine the potential relevance of PD-linked genetic mutations to altered immune function and the extent to which environmental exposures that recapitulate these phenotypes, which may lead to sporadic PD through similar mechanisms. Given the implications of immune system involvement on disease progression, we conclude by reviewing the evidence supporting the potential efficacy of immunomodulatory therapies in PD prevention or treatment. There is a clear need for additional research to clarify the role of immunity and inflammation in this chronic, neurodegenerative disease.

Alterations in brain structure and function in breast cancer survivors: effect of post-chemotherapy interval and relation to oxidative DNA damage

Neuroimaging studies have begun to uncover the neural substrates of cancer and treatment-related cognitive dysfunction, but the time course of these changes in the years following chemotherapy is unclear. This study analyzed multimodality 3T MRI scans to examine the structural and functional effects of chemotherapy and post-chemotherapy interval (PCI) in a cohort of breast cancer survivors (BCS; n = 24; PCI mean 6, range 3-10 y) relative to age- and education-matched healthy controls (HC; n = 23). Assessments included voxel-based morphometry for gray matter density (GMD) and fMRI for activation profile during a 3-back working memory task. The relationships between brain regions associated with PCI and neuropsychological performance, self-reported cognition, and oxidative and direct DNA damage as measured in peripheral lymphocytes were assessed in secondary analyses. PCI was positively associated with GMD and activation on fMRI in the right anterior frontal region (Brodmann Areas 9 and 10) independent of participant age. GMD in this region was also positively correlated with global neuropsychological function. Memory dysfunction, cognitive complaints, and oxidative DNA damages were increased in BCS compared with HC. Imaging results indicated lower fMRI activation in several regions in the BCS group. BCS also had lower GMD than HC in several regions, and in these regions, GMD was inversely related to oxidative DNA damage and learning and memory neuropsychological domain scores. This is the first study to show structural and functional effects of PCI and to relate oxidative DNA damage to brain alterations in BCS. The relationship between neuroimaging and cognitive function indicates the potential clinical relevance of these findings. The relationship with oxidative DNA damage provides a mechanistic clue warranting further investigation.

Ogg1 null mice exhibit age-associated loss of the nigrostriatal pathway and increased sensitivity to MPTP

Cumulative damage to cellular macromolecules via oxidative stress is a hallmark of aging and neurodegenerative disease. Whether such damage is a cause or a subsequent effect of neurodegeneration is still unknown. This paper describes the development of an age-associated mild parkinsonian model in mice that lack the DNA repair enzyme 8-oxoguanine glycosylase 1 (Ogg1). Aged OGG1 knock-out (OGG1 KO) mice show a decreased spontaneous locomotor behavior and evidence a decrease in striatal dopamine levels, a loss of tyrosine hydroxylase (TH)-positive neurons in the substantia nigra (SN), and an increase in ubiquitin-positive inclusions in their remaining SN neurons. In addition, young OGG1 KO mice are more susceptible to the dopaminergic toxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) than their wild-type (WT) counterparts. Age-associated increases in 7,8-dihydro-2'-deoxyguanine (oxo(8)dG) have been reported in brain regions and neuronal populations affected in Parkinson's disease (PD), toxin-induced parkinsonian models, and mice harboring genetic abnormalities associated with PD. Because of these increased oxo(8)dG levels, the OGG1 KO mouse strain could shed light on molecular events leading to neuronal loss as a consequence of cumulative oxidative damage to DNA during aging and after toxicological challenge.

NADPH oxidase 1-mediated oxidative stress leads to dopamine neuron death in Parkinson's disease

AIM

Oxidative stress has long been considered as a major contributing factor in the pathogenesis of Parkinson's disease. However, molecular sources for reactive oxygen species in Parkinson's disease have not been clearly elucidated. Herein, we sought to investigate whether a superoxide-producing NADPH oxidases (NOXs) are implicated in oxidative stress-mediated dopaminergic neuronal degeneration.

RESULTS

Expression of various Nox isoforms and cytoplasmic components were investigated in N27, rat dopaminergic cells. While most of Nox isoforms were constitutively expressed, Nox1 expression was significantly increased after treatment with 6-hydroxydopamine. Rac1, a key regulator in the Nox1 system, was also activated. Striatal injection of 6-hydroxydopamine increased Nox1 expression in dopaminergic neurons in the rat substantia nigra. Interestingly, it was localized into the nucleus, and immunostaining for DNA oxidative stress marker, 8-oxo-dG, was increased. Nox1 expression was also found in the nucleus of dopaminergic neurons in the substantia nigra of Parkinson's disease patients. Adeno-associated virus-mediated Nox1 knockdown or Rac1 inhibition reduced 6-hydroxydopamine-induced oxidative DNA damage and dopaminergic neuronal degeneration significantly.

INNOVATION

Nox1/Rac1 could serve as a potential therapeutic target for Parkinson's disease.

CONCLUSION

We provide evidence that dopaminergic neurons are equipped with the Nox1/Rac1 superoxide-generating system. Stress-induced Nox1/Rac1 activation causes oxidative DNA damage and neurodegeneration. Reduced dopaminergic neuronal death achieved by targeting Nox1/Rac1, emphasizes the impact of oxidative stress caused by this system on the pathogenesis and therapy in Parkinson's disease.

Aging-associated alteration of telomere length and subtelomeric status in female patients with Parkinson's disease

A telomere is a repetitive DNA structure at chromosomal ends that stabilizes the chromosome structure and prevents harmful end-to-end recombinations. The telomere length of somatic cells becomes shorter with aging because of the "end replication problem." This telomere shortening is accelerated by pathophysiological conditions including daily mental stress. Living with Parkinson's disease (PD) causes physical and mental stress; therefore, the authors hypothesized that the telomere length of somatic cells was shortened excessively in patients with PD. In order to detect PD-associated somatic telomeric alterations, the telomere length and subtelomeric methylation status of peripheral leukocytes of PD patients were assessed by Southern blotting, using methylation-sensitive and -insensitive isoschizomers. The results demonstrated that the peripheral leukocytes of Japanese female patients with PD bore fewer long telomeres and a proportional increase of hypomethylated subtelomeres in short telomeres in comparison with the healthy controls. This study indicates that with the neurodegeneration associated with PD, telomeric and subtelomeric structural alterations occur. These structural telomere alterations most likely occur secondary to the acceleration of aging-associated telomeric changes and the accelerated loss of cells bearing short telomeres.

General anesthesia-associated DNA damage in peripheral blood mononuclear cells of surgical patients

OBJECTIVE

To evaluate retrospectively the effect of general anesthesia on DNA damage in the blood mononuclear cells (PBMCs) of surgical patients in order to provide evidence for a better nursing care during the procedure.

METHODS

Clinical charts of 76 patients who underwent operation under general anesthesia and 76 healthy control subjects with documented results of DNA damage extent in PBMCs from the single-cell gel electrophoresis (SCGE) or comet assay and serum contents of superoxide dismutase (SOD) and malondialdehyde (MDA) from biochemical analyses were reviewed. The percentage of comet PBMCs and tail DNA and serum contents of SOD and MAD were analyzed by student t-test.

RESULTS

Compared with healthy control subjects, generally anesthetized surgical patients had significantly higher % comet PBMCs and % tail DNA (P <0.05) and significantly lower serum concentrations of SOD (P<0.05) and significantly higher serum concentrations of MAD (P<0.05). Compared with levels before general anesthesia in surgical patients, % comet PBMCs, % tail DNA, and serum levels of MAD were significantly higher (P<0.05 or 0.01, and serum levels of SOD were significantly lower (P<0.05, after general anesthesia.

CONCLUSIONS

General anesthesia during surgery causes a certain degree of hypoxia and PBMC damage. Particular attention should be paid to monitoring and maintenance of blood oxygen saturation in patients undergoing surgery under general anesthesia.

Association of micronucleus frequency with neurodegenerative diseases

Micronuclei (MNi) can originate either from chromosome breakage or chromosome malsegregation events and are therefore ideal biomarkers to investigate genomic instability. Studies in peripheral lymphocytes of patients with neurodegenerative diseases, mainly Alzheimer's disease (AD) and Parkinson's disease (PD), revealed an increased micronucleus (MN) frequency in both disorders but originating mainly from chromosome malsegregation events in AD and from chromosome breakage events in PD. Studies in other neurodegenerative diseases are largely missing, and some data in premature ageing disorders characterised by neurodegeneration and/or neurological complications, such as Ataxia telangiectasia, Werner's syndrome, Down's syndrome (DS) and Cockayne's syndrome, indicate that MNi increase with ageing in cultured cells. An increased frequency of aneuploidy characterises several tissues of AD patients, as well as of individuals at increased risk to develop AD, such as mothers of DS individuals and DS subjects themselves. The use of the buccal MN cytome assay in AD and DS subjects allowed finding significant changes in the MN frequency as well as other cellular modifications reflecting reduced regenerative capacity compared to age- and gender-matched controls. These changes in buccal cytome ratios may prove useful as potential future diagnostics to identify individuals of increased risk for these disorders.

Nuclear damage in peripheral lymphocytes of obese and overweight Italian children as evaluated by the gamma-H2AX focus assay and micronucleus test

Childhood obesity, often characterized by a chronic low-grade inflammation, has been associated with an increased risk of developing some types of cancer later in life. Nuclear γ-H2AX foci represent the first detectable response of cells to DNA tumorigenesis lesions, such as the double-strand breaks (DSBs). An excess of micronucleated peripheral lymphocytes was found in subjects with cancer or inflammation-based diseases. We set out to investigate the expression of genome damage, from DNA lesions to chromosome mutations (micronuclei), in overweight and obese children. Using the γ-H2AX focus assay and micronucleus (MN) test, we analyzed peripheral lymphocytes from 119 Italian children classified as normal weight (n=38), overweight (n=20), or obese (n=61). Cultures treated with bleomycin (BLM) were also set up for each child in both assays to check functioning of the apparatus that ensures DNA integrity. We measured serum TNF-α, IL-6, and C-reactive protein (CRP) as markers of inflammation. Overweight and obese children had significantly higher levels of H2AX phosphorylation (0.0191±0.0039 and 0.0274±0.0029 γ-H2AXF/n) and increased MN frequencies (2.30±0.25 and 2.45±0.22‰) than normal-weight children (0.0034±0.0006 γ-H2AXF/n, and 0.92±0.12‰ MN), while all subjects responded to BLM induction, irrespective of their weight status. The fold increase of spontaneous MN frequencies in overweight and obese subjects was 2.5 and 2.7, respectively, well below the corresponding increase in the γ-H2AX foci (5.6- and 8.0-fold, respectively). IL-6 and CRP mean values were significantly higher in obese and overweight children than in controls. Here, we demonstrated that peripheral cells of overweight and obese children showed increased levels of DSBs, which were not completely repaired as part of them has been converted into micronuclei. Characterization of childhood obesity inflammation could be implemented using molecular markers of genome damage.

The role of the dopamine transporter in dopamine-induced DNA damage

The neurotransmitter dopamine causes DNA damage, oxidative stress and is involved in the pathology of neurological diseases. To elucidate this potential link we investigated the mechanism of dopamine-induced DNA damage. We studied the role of the dopamine transporter (DAT) in MDCK and MDCK-DAT cells, containing the human DAT gene. After treatment with dopamine, only MDCK-DAT cells showed elevated chromosomal damage and dopamine uptake. Although stimulation of dopamine type 2 receptor (D(2)R) with quinpirole in the absence of dopamine did not induce genotoxicity in rat neuronal PC12 cells, interference with D(2)R signaling by inhibition of G-proteins, phosphoinositide 3 kinase and extracellular signal-regulated kinases reduced dopamine-induced genotoxicity and affected the ability of DAT to take up dopamine. Furthermore, the D(2)R antagonist sulpiride inhibited the dopamine-induced migration of DAT from cytosol to cell membrane. To determine whether oxidation of dopamine by monoamine oxidase (MAO) is relevant in its genotoxicity, we inhibited MAO, which reduced the formation of micronuclei and of the oxidative DNA adduct 8-oxodG. Overall, dopamine exerted its genotoxicity in vitro upon transport into the cells and oxidation by MAO. D(2)R signaling was involved in the genotoxicity of dopamine by affecting activation and cell surface expression of DAT and hence modulating dopamine uptake.

Biomarkers for prediction and targeted prevention of Alzheimer's and Parkinson's diseases: evaluation of drug clinical efficacy

Neurodegenerative diseases like Parkinson’s disease (PD) and Alzheimer’s disease (AD) are considered disorders of multifactorial origin, inevitably progressive and having a long preclinical period. Therefore, the availability of biological markers or biomarkers (BMs) for early disease diagnosis will impact the management of AD and PD in several dimensions; it will 1) help to capture high-risk individuals before symptoms develop, a stage where prevention efforts might be expected to have their greatest impact; 2) provide a measure of disease progression that can be evaluated objectively, while clinical measures are much less accurate; 3) help to discriminate between true AD or PD and other causes of a similar clinical syndrome; 4) delineate pathophysiological processes responsible for the disease; 5) determine the clinical efficacy of novel, disease-modifying (neuroprotective) strategies. In the long run the availability of reliable BMs will significantly advance the research and therapeutics of AD and PD.

Peripheral biomarkers of Parkinson's disease as early reporters of central neurodegeneration

Parkinson's disease (PD) is the most common age-related movement disorder, with a prevalence of approximately 2% among people over 65 years of age. The diagnosis of PD is currently based on the clinical manifestations of the disease; therefore, the availability of peripheral biomarkers would have a great impact. In this review, we discuss and compare several attempts made to find peripheral biomarkers of PD to achieve early diagnosis, differential diagnosis, therapy assessment and classification of disease subtypes. Several investigators focused on proteins that are involved in PD pathogenesis. However, the best choice for a sensible biomarker-discovery procedure makes use of global approaches such as metabolomics and proteomics. In addition, the tissue or compartment where biomarkers are located, plays a basic role. In this context, lymphocytes are of particular interest because they are circulating dopaminergic cells, and display several functional modifications in PD.