Plasma oxidative and inflammatory markers in patients with idiopathic Parkinson's disease

From Gut to Brain: Uncovering Potential Serum Biomarkers Connecting Inflammatory Bowel Diseases to Neurodegenerative Diseases

Inflammatory bowel diseases (IBDs) are characterized by chronic gastrointestinal inflammation due to abnormal immune responses to gut microflora. The gut-brain axis is disrupted in IBDs, leading to neurobiological imbalances and affective symptoms. Systemic inflammation in IBDs affects the brain's inflammatory response system, hormonal axis, and blood-brain barrier integrity, influencing the gut microbiota. This review aims to explore the association between dysregulations in the gut-brain axis, serum biomarkers, and the development of cognitive disorders. Studies suggest a potential association between IBDs and the development of neurodegeneration. The mechanisms include systemic inflammation, nutritional deficiency, GBA dysfunction, and the effect of genetics and comorbidities. The objective is to identify potential correlations and propose future research directions to understand the impact of altered microbiomes and intestinal barrier functions on neurodegeneration. Serum levels of vitamins, inflammatory and neuronal damage biomarkers, and neuronal growth factors have been investigated for their potential to predict the development of neurodegenerative diseases, but current results are inconclusive and require more studies.

Relationship between Parkinson's disease and cardio-cerebrovascular diseases: a Mendelian randomized study

Parkinson's disease (PD) and cardio-cerebrovascular diseases are related, according to earlier studies, but these studies have some controversy. Our aim was to assess the impact of PD on cardiocerebrovascular diseases using a Mendelian randomization (MR) method. The data for PD were single nucleotide polymorphisms (SNPs) from a publicly available genome-wide association study (GWAS) dataset containing data on 482,730 individuals. And the outcome SNPs data is were derived from five different GWAS datasets. The basic method for MR analysis was the inverse variance weighted (IVW) approach. We use the weighted median method and the MR-Egger method to supplement the MR analysis conclusion. Finally, We used Cochran's Q test to test heterogeneity, MR-PRESSO method and leave-one-out analysis method to perform sensitivity analysis. We used ratio ratios (OR) to assess the strength of the association between exposure and outcome, and 95% confidence intervals (CI) to show the reliability of the results. Our findings imply that PD is linked to a higher occurrence of coronary artery disease (CAD) (OR = 1.055, 95% CI 1.020-1.091, P = 0.001), stroke (OR = 1.039, 95% CI 1.007-1.072, P = 0.014). IVW analyses for stroke's subgroups of ischemic stroke (IS) and 95% CI 1.007-1.072, P = 0.014). IVW analyses for stroke's subgroups of ischemic stroke (IS) and cardioembolic stroke (CES) also yielded positive results, respectively (OR = 1.043, 95% CI 1.008-1.079, P = 0.013), (OR = 1.076, 95% CI 1.008-1.149, P = 0.026). There is no evidence of a relationship between PD and other cardio-cerebrovascular diseases. Additionally, sensitivity analysis revealed reliable outcomes. Our MR study analysis that PD is related with an elevated risk of CAD, stroke, IS, and CES.

C-reactive protein as the biomarker of choice to monitor the effects of exercise on inflammation in Parkinson's disease

Parkinson's disease (PD), a heterogeneous disease with no disease-modifying treatments available, is the fastest growing neurological disease worldwide. Currently, physical exercise is the most promising treatment to slow disease progression, with evidence suggesting it is neuroprotective in animal models. The onset, progression, and symptom severity of PD are associated with low grade, chronic inflammation which can be quantified by measuring inflammatory biomarkers. In this perspective, we argue that C-reactive protein (CRP) should be used as the primary biomarker for monitoring inflammation and therefore disease progression and severity, particularly in studies examining the impact of an intervention on the signs and symptoms of PD. CRP is the most studied biomarker of inflammation, and it can be detected using relatively well-standardized assays with a wide range of detection, allowing for comparability across studies while generating robust data. An additional advantage of CRP is its ability to detect inflammation irrespective of its origin and specific pathways, an advantageous characteristic when the cause of inflammation remains unknown, such as PD and other chronic, heterogeneous diseases.

Blood Biomarkers in Patients with Parkinson's Disease: A Review in Context of Anesthetic Care

Parkinson's disease (PD) is the second most common inflammatory neurodegenerative disorder after dementia. Preclinical and epidemiological data strongly suggest that chronic neuroinflammation slowly induces neuronal dysfunction. Activated microglia secrete several neurotoxic substances, such as chemokines and proinflammatory cytokines, which may promote blood-brain barrier (BBB) permeabilization. CD4⁺ T cells comprise proinflammatory cells such as T helper (Th) 1 and Th17 cells, as well as anti-inflammatory cells such as Th2 and T regulatory cells (Tregs). Th1 and Th17 cells can be detrimental to dopamine neurons, whereas Th2 and Tregs are neuroprotective. The results of studies on the serum levels of cytokines such as IFN-γ and TNF-α secreted by Th1 T cells, IL-8 and IL-10 secreted by Th2 T cells, and IL-17 secreted by Th17 cells in PD patients are not uniform. In addition, the relationships between serum cytokine levels and motor and non-motor symptoms of PD are controversial. Surgical stress and anesthesia induce inflammatory responses by disturbing the balance between pro- and anti-inflammatory cytokines, which may exacerbate the neuroinflammatory response in PD patients. Here we review studies on blood inflammatory biomarkers in PD patients and discuss the roles of surgery and anesthesia in PD progression.

Role of High-Sensitivity C-reactive Protein (Hs-CRP) in Non-communicable Diseases: A Review

Non-communicable diseases like cardiovascular diseases, cerebrovascular diseases, diabetes mellitus, and cancer are very common causes of death worldwide. Therefore, the need to search for novel, affordable, and easily accessible biomarkers and risk factors for non-communicable diseases continues, which can predict the future risk of having these diseases with greater accuracy and precision. In this context, among available biomarkers, high-sensitivity C-reactive protein (Hs-CRP) is considered to be the best-suited marker. Various drug intervention trials demonstrated positive results in reducing Hs-CRP in individuals with raised levels. Numerous pharmacological and non-pharmacologic interventions in the form of lifestyle modifications, exercise, and cessation of smoking are being investigated to study their effect on reducing serum C-reactive protein (CRP) levels.

This review article discusses the role of Hs-CRP and its isoforms in the pathogenesis of various disease conditions, factors affecting its serum concentration, its prognostic value, and its comparison with other risk factors. Further, its clinical significance in chronic inflammatory and degenerative diseases of the nervous system and other common non-communicable diseases, including recent advances in the management of various diseases, has also been discussed.

Long noncoding RNA SNHG14 knockdown exerts a neuroprotective role in MPP+-induced Parkinson's disease cell model through mediating miR-135b-5p/KPNA4 axis

BACKGROUND

Parkinson's disease (PD) is a neurodegenerative disease resulted from the loss of dopaminergic neurons. Here, we analyzed the role of long noncoding RNA (lncRNA) small nucleolar RNA host gene 14 (SNHG14) in PD using 1-methyl-4-phenyl pyridine (MPP⁺)-induced PD cell model.

METHODS

Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blot assay were performed to determine RNA and protein expression, respectively. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and flow cytometry (FCM) analysis were conducted to analyze cell viability and apoptosis. Enzyme-Linked Immunosorbent Assay (ELISA) was conducted to analyze the release of inflammatory cytokines. Cytotoxicity was assessed using reactive oxygen species (ROS) assay kit, superoxide dismutase (SOD) activity assay kit and lactate dehydrogenase (LDH) activity assay kit. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were performed to confirm the interaction between microRNA-135b-5p (miR-135b-5p) and SNHG14 or karyopherin subunit alpha 4 (KPNA4).

RESULTS

MPP⁺ treatment elevated the expression of SNHG14 in SK-N-SH cells in a dose and time-dependent manner. SNHG14 knockdown alleviated MPP⁺-induced apoptosis, inflammation, and cytotoxicity in SK-N-SH cells. SNHG14 interacted with miR-135b-5p, and SNHG14 silencing-mediated effects were partly overturned by miR-135b-5p knockdown in PD cell model. Besides, miR-135b-5p interacted with the 3' untranslated region (3'UTR) of KPNA4, and KPNA4 overexpression partly reversed miR-135b-5p overexpression-induced effects in PD cell model. SNHG14 knockdown reduced the protein level of KPNA4 partly by up-regulating miR-135b-5p in SK-N-SH cells.

CONCLUSION

SNHG14 promoted MPP⁺-induced neuro injury in PD cell model through mediating miR-135b-5p/KPNA4 axis.

MALAT1 lncRNA and Parkinson's Disease: The role in the Pathophysiology and Significance for Diagnostic and Therapeutic Approaches

Parkinson's disease (PD) is the second most common age-related neurodegenerative disorder. PD is characterized by progressive loss of dopamine-producing neurons in the substantia nigra (SN) region of brain tissue followed by the α-synuclein-based Lewy bodies' formation. These conditions are manifested by various motor and non-motor symptoms such as resting tremor, limb rigidity, bradykinesia and posture instability, cognitive impairment, sleep disorders, and emotional and memory dysfunctions. Long non-coding RNAs (lncRNAs) are closely related to protein-coding genes and are involved in various biological processes. Metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) lncRNA is involved in different pathways, including alternative splicing, transcriptional regulation, and post-transcriptional regulation, and also interacts with RNAs as a miRNA sponge. MALAT1 is highly expressed in brain tissues and several lines of evidence suggested it is probably involved in synapse generation and other neurophysiological pathways. This narrative review discussed all aspects of MALAT1-associated mechanisms involved in the PD pathogenesis, i.e., perturbed α-synuclein homeostasis, apoptosis and autophagy, and neuro-inflammation. Lastly, the possible applications of MALAT1 as a diagnostic biomarker and its importance to developing therapeutic strategies were highlighted. The literature search was conducted using neurodegeneration, neurodegenerative disorders, Parkinson's disease, lncRNA, and MALAT1 as search items in Google Scholar, Web of Knowledge, PubMed, and Scopus up to December 2021.

Propagation of age‐related diseases due to the changes of lipid peroxide and antioxidant levels in elderly people: A narrative review

Background and Aims

Lipid peroxidation end products are the major culprit for inducing chronic diseases in elderly people. Along with the elevated level of lipid peroxide biomarkers, there is a significant disruption of antioxidants balance, which combinedly propagate the diseases of elderly people. The aim of the present review is to bridge the connection of changes in lipid peroxides biomarkers and antioxidants level with age‐associated diseases in elderly people.

Methods

This narrative review was performed following a comprehensive search for suitable articles in multiple online databases, including PubMed, Google Scholar, EMBASE, Web of Science, Cochrane Library, and ScienceDirect using selected search terms. The most appropriate literature was included based on the selection criteria.

Results

From the review, it is found that many age‐related diseases propagated with an increased level of the end products of lipid peroxide and reduced levels of antioxidants in elderly people. When the end products of lipid peroxidation increase in the body, it creates oxidative stress, which ultimately leads to many complicated diseases, including cancers, cardiovascular and neurogenic diseases, and many other chronic inflammatory diseases. The oxidative stress induced by peroxidation can be assessed by different lipid peroxide end products such as malondialdehyde, oxidized low‐density lipoprotein, isoprostanes, neuroprostanes, lipoperoxides, oxysterols (7‐ketocholesterol, 7β‐hydroxycholesterol), and many more.

Conclusions

This study definitively answers the correlation between the changes in lipid peroxides and antioxidants level and age‐related diseases. Our narrative article recommends future investigations for elucidating the mechanisms rigorously to establish a compact correlation.

Biomarker of Neuroinflammation in Parkinson's Disease

Parkinson's disease (PD) is caused by abnormal accumulation of α-synuclein in dopaminergic neurons of the substantia nigra, which subsequently causes motor symptoms. Neuroinflammation plays a vital role in the pathogenesis of neurodegeneration in PD. This neuroinflammatory neurodegeneration involves the activation of microglia, upregulation of proinflammatory factors, and gut microbiota. In this review, we summarized the recent findings on detection of PD by using inflammatory biomarkers, such as interleukin (IL)-1β, IL-2, IL-6, IL-10, tumor necrosis factor (TNF)-α; regulated upon activation, normal T cell expressed and presumably secreted (RANTES) and high-sensitivity c-reactive protein (hsCRP); and radiotracers such as [11C]PK11195 and [18F]-FEPPA, as well as by monitoring disease progression and the treatment response. Many PD-causing mutations in SNCA, LRRK2, PRKN, PINK1, and DJ-1 are also associated with neuroinflammation. Several anti-inflammatory medications, including nonsteroidal anti-inflammatory drugs (NSAID), inhibitors of TNF-α and NLR family pyrin domain containing 3 (NLRP3), agonists of nuclear factor erythroid 2-related factor 2 (NRF2), peroxisome proliferator-activated receptor gamma (PPAR-γ), and steroids, have demonstrated neuroprotective effects in in vivo or in vitro PD models. Clinical trials applying objective biomarkers are required to investigate the therapeutic potential of anti-inflammatory medications for PD.

Role of exosomes in the pathogenesis of inflammation in Parkinson's disease

Inflammatory responses, including glial cell activation and peripheral immune cell infiltration, are involved in the pathogenesis of Parkinson’s disease (PD). These inflammatory responses appear to be closely related to the release of extracellular vesicles, such as exosomes. However, the relationships among different forms of glial cell activation, synuclein dysregulation, mitochondrial dysfunction, and exosomes are complicated. This review discusses the multiple roles played by exosomes in PD-associated inflammation and concludes that exosomes can transport toxic α-synuclein oligomers to immature neurons and into the extracellular environment, inducing the oligomerization of α-synuclein in normal neurons. Misfolded α-synuclein causes microglia and astrocytes to activate and secrete exosomes. Glial cell-derived exosomes participate in communications between glial cells and neurons, triggering anti-stress and anti-inflammatory responses, in addition to axon growth. The production and release of mitochondrial vesicles and exosomes establish a new mechanism for linking mitochondrial dysfunction to systemic inflammation associated with PD. Given the relevance of exosomes as mediators of neuron-glia communication in neuroinflammation and neuropathogenesis, new targeted treatment strategies are currently being developed that use these types of extracellular vesicles as drug carriers. Exosome-mediated inflammation may be a promising target for intervention in PD patients.

Blood and Cerebrospinal Fluid Biomarkers of Inflammation in Parkinson's Disease

Given the clear role of inflammation in the pathogenesis of Parkinson's disease (PD) and its impact on incidence and phenotypical characteristics, this review provides an overview with focus on inflammatory biofluid markers in blood and cerebrospinal fluid (CSF) in PD patient cohorts. In preparation for clinical trials targeting the immune system, we specifically address the following questions: 1) What evidence do we have for pro-inflammatory profiles in blood and in CSF of sporadic and genetic PD patients? 2) Is there a role of anti-inflammatory mediators in blood/CSF? 3) Do inflammatory profiles in blood reflect those in CSF indicative of a cross-talk between periphery and brain? 4) Do blood/CSF inflammatory profiles change over the disease course as assessed in repeatedly taken biosamples? 5) Are blood/CSF inflammatory profiles associated with phenotypical trajectories in PD? 6) Are blood/CSF inflammatory profiles associated with CSF levels of neurodegenerative/PD-specific biomarkers? Knowledge on these questions will inform future strategies for patient stratification and cohort enrichment as well as suitable outcome measures for clinical trials.

Parkinson's Disease-Related Biomarkers That May Appear in Amphetamine Abusers

Parkinson's disease (PD) is one of the most common neurodegenerative disorders. Amphetamine addiction may cause serious of psychotic and physical damage to humans. There is some evidence that shows that amphetamine may increase the risk of PD. Thus, this study is aimed at comparing the PD serum biomarkers between amphetamine addicts and PD patients and utilizing them as diagnostic biomarkers for the early detection of PD incidence among amphetamine addicts. In the current study, nineteen amphetamine addicts, aged <40, were recruited from the Al Amal Psychiatric hospital, Jazan, Saudi Arabia. Nineteen PD patients and 19 healthy controls, who have never taken amphetamine, were also recruited. Blood samples were withdrawn from all groups. A biomarker multiplex assay from MILLIPLEX was used to assess the levels of serum amyloid-P (SAP), complement C4, C-reactive protein (CRP), and CRP/albumin ratio in serum samples (Vitros 350® slide was used to assess the albumin). All data were statistically analyzed using one-way ANOVA. The results showed that SAP and CRP levels were significantly higher in amphetamine addicts compared to healthy controls (p = 0.0001 and p = 0.0001, respectively). The results of amphetamine addicts were comparable to PD levels. However, there are no significant differences between all studied groups concerning complement C4 level. Moreover, albumin levels were significantly decreased and CRP/Albumin ratio levels were significantly increased in amphetamine addicts (p = 0.01 and p = 0.041, respectively) in contrast with controls. These findings indicate that the increased level of these inflammatory biomarkers (SAP and CRP) in the amphetamine addicts may give a potential possibility of their serum level to be used as screening markers to detect PD development in the amphetamine addict. It may be useful to evaluate the changes in easily accessible and cost-effective parameters such as the serum CRP/albumin ratio.

The Effects of Aerobic Exercise on Oxidative Stress in Older Adults: A Systematic Review and Meta-Analysis

Background: Oxidative stress (OS) plays an important role in the progression of many aging-related diseases. Exercises can delay this kind of progress, but aerobic exercise is the most commonly used type of training among older adults; therefore, its influence needs to be further verified.

Methods: A literature search was conducted in eight electronic databases, including Cochrane, EMBASE, PubMed, Web of Science, China National Knowledge Infrastructure (CNKI), China Science and Technology Journal Database (VIP), Wanfang Date, and SinoMed from their inception to April 2020. Methodological quality was assessed using Cochrane RoB tool v2.0 for individual studies, and RevMan 5.3 software was used to perform the meta-analysis.

Results: The meta-analysis included 20 studies, involving 1,170 older adults. The results showed that regular aerobic exercise could reduce blood oxidant markers, including malondialdehyde (MDA; SMD=−1.80, 95% CI −2.46 to −1.14, p<0.001) and lipid peroxide (LPO; SMD=−1.12, 95% CI −2.03 to −0.22, p=0.02), and increase the levels of antioxidant factors, such as nitric oxide (NO; SMD=0.89, 95% CI 0.37–1.41, p<0.001), superoxide dismutase (SOD; SMD=0.63, 95% CI 0.25–1.01, p=0.001), and total antioxidant capacity (TAC; SMD=1.22, 95% CI 0.45–1.98, p=0.002), with clear statistical significance. It may also improve the levels of other OS markers, such as 8-OHdG, 8-isoPGF2, VE, and reduced glutathione/oxidized glutathione (GSH/GSSG).

Conclusion: Regular aerobic exercise may have a positive effect on the OS levels of older adults by reducing some oxidant markers and increasing antioxidant marker levels.

Increased YKL-40 but Not C-Reactive Protein Levels in Patients with Alzheimer's Disease

Neuroinflammation is a common feature in Alzheimer’s (AD) and Parkinson’s (PD) disease. In the last few decades, a testable hypothesis was proposed that protein-unfolding events might occur due to neuroinflammatory cascades involving alterations in the crosstalk between glial cells and neurons. Here, we tried to clarify the pattern of two of the most promising biomarkers of neuroinflammation in cerebrospinal fluid (CSF) in AD and PD. This study included cognitively unimpaired elderly patients, patients with mild cognitive impairment, patients with AD dementia, and patients with PD. CSF samples were analyzed for YKL-40 and C-reactive protein (CRP). We found that CSF YKL-40 levels were significantly increased only in dementia stages of AD. Additionally, increased YKL-40 levels were found in the cerebral orbitofrontal cortex from AD patients in agreement with augmented astrogliosis. Our study confirms that these biomarkers of neuroinflammation are differently detected in CSF from AD and PD patients.

Aiding and Abetting Anhedonia: Impact of Inflammation on the Brain and Pharmacological Implications

Exogenous administration of inflammatory stimuli to humans and laboratory animals and chronic endogenous inflammatory states lead to motivational deficits and ultimately anhedonia, a core and disabling symptom of depression present in multiple other psychiatric disorders. Inflammation impacts neurotransmitter systems and neurocircuits in subcortical brain regions including the ventral striatum, which serves as an integration point for reward processing and motivational decision-making. Many mechanisms contribute to these effects of inflammation, including decreased synthesis, release and reuptake of dopamine, increased synaptic and extrasynaptic glutamate, and activation of kynurenine pathway metabolites including quinolinic acid. Neuroimaging data indicate that these inflammation-induced neurotransmitter effects manifest as decreased activation of ventral striatum and decreased functional connectivity in reward circuitry involving ventral striatum and ventromedial prefrontal cortex. Neurocircuitry changes in turn mediate nuanced effects on motivation that include decreased willingness to expend effort for reward while maintaining the ability to experience reward. Taken together, the data reveal an inflammation-induced pathophysiologic phenotype that is agnostic to diagnosis. Given the many mechanisms involved, this phenotype represents an opportunity for development of novel and/or repurposed pharmacological strategies that target inflammation and associated cellular and systemic immunometabolic changes and their downstream effects on the brain. To date, clinical trials have failed to capitalize on the unique nature of this transdiagnostic phenotype, leaving the field bereft of interpretable data for meaningful clinical application. However, novel trial designs incorporating established targets in the brain and/or periphery using relevant outcome variables (e.g., anhedonia) are the future of targeted therapy in psychiatry. SIGNIFICANCE STATEMENT: Emerging understanding of mechanisms by which peripheral inflammation can affect the brain and behavior has created unprecedented opportunities for development of pharmacological strategies to treat deficits in motivation including anhedonia, a core and disabling symptom of depression well represented in multiple psychiatric disorders. Mechanisms include inflammation and cellular and systemic immunometabolism and alterations in dopamine, glutamate, and kynurenine metabolites, revealing a target-rich environment that nevertheless has yet to be fully exploited by current clinical trial designs and drugs employed.

Oxidative stress factors in Parkinson's disease

Parkinson's disease (PD) is the second most common cause of neurodegeneration. Over the last two decades, various hypotheses have been proposed to explain the etiology of PD. Among these is the oxidant-antioxidant theory, which asserts that local and systemic oxidative damage triggered by reactive oxygen species and other free radicals may promote dopaminergic neuron degeneration. Excessive reactive oxygen species formation, one of the underlying causes of pathology in the course of PD has been evidenced by various studies showing that oxidized macromolecules including lipids, proteins, and nucleic acids accumulate in brain tissues of PD patients. DNA oxidation may produce various lesions in the course of PD. Mutations incurred as a result of DNA oxidation may further enhance reactive oxygen species production in the brains of PD patients, exacerbating neuronal loss due to defects in the mitochondrial electron transport chain, antioxidant depletion, and exposure to toxic oxidized dopamine. The protein products of SNCA, PRKN, PINK1, DJ1, and LRRK2 genes are associated with disrupted oxidoreductive homeostasis in PD. SNCA is the first gene linked with familial PD and is currently known to be affected by six mutations correlated with the disorder: A53T, A30P, E46K, G51D, H50Q and A53E. PRKN encodes Parkin, an E3 ubiquitin ligase which mediates the proteasome degradation of redundant and disordered proteins such as glycosylated α-synuclein. Over 100 mutations have been found among the 12 exons of PRKN. PINK1, a mitochondrial kinase highly expressed in the brain, may undergo loss of function mutations which constitute approximately 1-8% of early onset PD cases. More than 50 PD-promoting mutations have been found in PINK1. Mutations in DJ-1, a neuroprotective protein, are a rare cause of early onset PD and constitute only 1% of cases. Around 20 mutations have been found in DJ1 among PD patients thus far. Mutations in the LRRK2 gene are the most common known cause of familial autosomal dominant PD and sporadic PD. Treatment of PD patients, especially in the advanced stages of the disease, is very difficult. The first step in managing progressive PD is to optimize dopaminergic therapy by increasing the doses of dopamine agonists and L-dopa. The next step is the introduction of advanced therapies, such as deep brain stimulation. Genetic factors may influence the response to L-dopa and deep brain stimulation therapy and the regulation of oxidative stress. Consequently, research into minimally invasive surgical interventions, as well as therapies that target the underlying etiology of PD is warranted.

Long non-coding RNA MALAT1 regulates cell proliferation and apoptosis via miR-135b-5p/GPNMB axis in Parkinson's disease cell model

Backgrounds

Parkinson’s disease (PD) is a common age-related neurodegenerative disorder worldwide. This research aimed to investigate the effects and mechanism underlying long non-coding RNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in PD.

Methods

SK-N-SH and SK-N-BE cells were treated with MPP⁺ to establish the MPP⁺-stimulated cell model of PD, and MALAT1 expression was determined. Then, the effects of MALAT1 depletion on cell proliferation and apoptosis were determined in the MPP⁺-stimulated cell model of PD. Besides, the correlations between microRNA-135b-5p (miR-135b-5p) and MALAT1 or glycoprotein nonmetastatic melanoma protein B (GPNMB) in MPP⁺-stimulated cell model of PD were explored.

Results

MALAT1 was increasingly expressed and downregulation of MALAT1 promoted cell proliferation while inhibited apoptosis in MPP⁺-stimulated cells. Besides, miR-135b-5p was a target of MALAT1 and directly targeted to GPNMB. Further investigation indicated that suppression of MALAT1 regulated cell proliferation and apoptosis by miR-135b-5p/GPNMB axis.

Conclusion

Our findings reveal that MALAT1/miR-135b-5p/GPNMB axis regulated cell proliferation and apoptosis in MPP⁺-stimulated cell model of PD, providing a potential biomarker and therapeutic target for PD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40659-021-00332-8.

The Impact of Air Pollution on Neurodegenerative Diseases

BACKGROUND

With the development of industrialization in human society, ambient pollutants are becoming more harmful to human health. Epidemiological and toxicological studies indicate that a close relationship exists between particulate matter with a diameter ≤2.5 µm (PM2.5) and neurodegenerative diseases such as Alzheimer's disease (AD) and Parkinson's disease (PD). To further confirm the relationship, we focus on possible relevant mechanisms of oxidative stress and neuroinflammation underlying the association between PM2.5 and neurodegenerative diseases in the review.

METHODS

A literature search was performed on the studies about PM2.5 and neurodegenerative diseases via PubMed. A total of 113 articles published were selected, and 31 studies were included.

RESULTS

PM2.5 can enter the central nervous system through 2 main pathways, the blood-brain barrier and olfactory neurons. The inflammatory response and oxidative stress are 2 primary mechanisms via which PM2.5 leads to toxicity in the brain. PM2.5 abnormally activates microglia, inducing the neuroinflammatory process. Inflammatory markers such as IL-1β play an essential role in neurodegenerative diseases such as AD and PD. Moreover, the association between lipid mechanism disorders related to PM2.5 and neurodegenerative diseases has been gaining momentum.

CONCLUSIONS

In conclusion, PM2.5 could significantly increase the risk of neurological disorders, such as AD and PD. Furthermore, any policy aimed at reducing air-polluting emissions and increasing air quality would be protective in human beings.

Effect of a High-Intensity Tandem Bicycle Exercise Program on Clinical Severity, Functional Magnetic Resonance Imaging, and Plasma Biomarkers in Parkinson's Disease

Rationale: The optimal modality, intensity, duration, frequency, and dose-response of exercise as a therapy for Parkinson's Disease (PD) are insufficiently understood. Objective: To assess the impact of a high-intensity tandem bicycle program on clinical severity, biomarkers, and functional MRI (fMRI) in PD. Methods: A single-center, parallel-group clinical trial was conducted. Thirteen PD patients aged 65 or younger were divided in two groups: a control group and an intervention group that incorporated a cycling program at 80% of each individual's maximum heart rate (HR) (≥80 rpm), three times a week, for 16 weeks. Both groups continued their conventional medications for PD. At baseline and at the end of follow-up, we determined in all participants the Unified Parkinson's Disease Rating Scale, anthropometry, VO₂max, PD biomarkers, and fMRI. Results: VO₂max improved in the intervention group (IG) (+5.7 ml/kg/min), while it slightly deteriorated in the control group (CG) (-1.6 ml/kg/min) (p = 0.041). Mean Unified Parkinson's Disease Rating Scale (UPDRS) went down by 5.7 points in the IG and showed a small 0.9-point increase in the CG (p = 0.11). fMRI showed activation of the right fusiform gyrus during the motor task and functional connectivity between the cingulum and areas of the frontal cortex, and between the cerebellar vermis and the thalamus and posterior temporal gyrus. Plasma brain-derived neurotrophic factor (BDNF) levels increased more than 10-fold in the IG and decreased in the CG (p = 0.028). Larger increases in plasma BDNF correlated with greater decreases in UPDRS (r = -0.58, p = 0.04). Conclusions: Our findings suggest that high-intensity tandem bicycle improves motor function and biochemical and functional neuroimaging variables in PD patients. Trial registration number: ISRCTN 13047118, Registered on February 8, 2018.

The Role of Oxidative Stress in Parkinson's Disease

Parkinson’s disease (PD) is caused by progressive neurodegeneration of dopaminergic (DAergic) neurons with abnormal accumulation of α-synuclein in substantia nigra (SN). Studies have suggested the potential involvement of dopamine, iron, calcium, mitochondria and neuroinflammation in contributing to overwhelmed oxidative stress and neurodegeneration in PD. Function studies on PD-causative mutations of SNCA, PRKN, PINK1, DJ-1, LRRK2, FBXO7 and ATP13A2 further indicate the role of oxidative stress in the pathogenesis of PD. Therefore, it is reasonable that molecules involved in oxidative stress, such as DJ-1, coenzyme Q10, uric acid, 8-hydroxy-2’-deoxyguanosin, homocysteine, retinoic acid/carotenes, vitamin E, glutathione peroxidase, superoxide dismutase, xanthine oxidase and products of lipid peroxidation, could be candidate biomarkers for PD. Applications of antioxidants to modulate oxidative stress could be a strategy in treating PD. Although a number of antioxidants, such as creatine, vitamin E, coenzyme Q10, pioglitazone, melatonin and desferrioxamine, have been tested in clinical trials, none of them have demonstrated conclusive evidence to ameliorate the neurodegeneration in PD patients. Difficulties in clinical studies may be caused by the long-standing progression of neurodegeneration, lack of biomarkers for premotor stage of PD and inadequate drug delivery across blood–brain barrier. Solutions for these challenges will be warranted for future studies with novel antioxidative treatment in PD patients.

Long noncoding RNA NEAT1 knockdown inhibits MPP+-induced apoptosis, inflammation and cytotoxicity in SK-N-SH cells by regulating miR-212-5p/RAB3IP axis

BACKGROUND

Some long non-coding RNAs (lncRNAs) have been suggested to play critical roles in Parkinson's disease (PD) pathogenesis, including nuclear enriched abundant transcript 1 (NEAT1). The purpose of this study was to further elucidate the molecular mechanism of NEAT1 in PD.

METHODS

The expression levels of NEAT1, miR-212-5p and RAB3A-interacting protein (RAB3IP) were determined by quantitative real-time polymerase chain reaction (qRT-PCR). Cell viability and apoptosis were evaluated by Cell Counting Kit-8 (CCK-8) assay and flow cytometry analysis, respectively. Western blot analysis was applied to detect the protein expression of IL-1β, TNF-α and RAB3IP. The LDH activity, ROS generation and SOD activity were measured by Lactate LDH activity assay kit, ROS assay kit, and SOD activity assay kit, respectively. Dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay were performed to verify the relationship between miR-212-5p and NEAT1 or mRNA of RAB3IP. 1-methyl-4-phenylpyridinium ion (MPP⁺)-treated SK-N-SH cells were used as an in vitro model of PD.

RESULTS

NEAT1 and RAB3IP were upregulated while miR-212-5p was downregulated in SK-N-SH cells treated with MPP⁺. NEAT1 knockdown or miR-212-5p overexpression inhibited MPP⁺-induced apoptosis, inflammation and cytotoxicity in SK-N-SH cells. Moreover, miR-212-5p was a direct target of NEAT1 and its downregulation reversed the eff ;ects caused by NEAT1 knockdown in MPP⁺-induced SK-N-SH cells. Furthermore, RAB3IP was a downstream target of miR-212-5p and its overexpression attenuated the effects of miR-212-5p restoration in MPP⁺-induced SK-N-SH cells. Besides, NEAT1 acted as a molecular sponge of miR-212-5p to regulate RAB3IP expression.

CONCLUSION

NEAT1 knockdown suppressed MPP⁺-induced apoptosis, inflammation and cytotoxicity in SK-N-SH cells through regulating miR-212-5p and RAB3IP expression, providing a possible therapeutic strategy for PD patients.

Understanding the links between cardiovascular disease and Parkinson's disease

Studies investigating the associations between genetic or environmental factors and Parkinson's disease (PD) have uncovered a number of factors shared with cardiovascular disease, either as risk factors or manifestations of cardiovascular disease itself. Older age, male sex, and possibly type 2 diabetes are examples. On the other hand, coffee consumption and physical activity are each associated with a lower risk of both PD and cardiovascular disease. This observation raises questions about the underlying pathophysiological links between cardiovascular disease and PD. There is evidence for common mechanisms in the areas of glucose metabolism, cellular stress, lipid metabolism, and inflammation. On the other hand, smoking and total/low-density lipoprotein cholesterol appear to have opposite associations with cardiovascular disease and PD. Thus, it is uncertain whether the treatment of cardiovascular risk factors will impact on the onset or progression of PD. The available data suggest that a nuanced approach is necessary to manage risk factors such as cholesterol levels once the associations are better understood. Ultimately, the choice of therapy may be tailored to a patient's comorbidity profile. This review presents the epidemiological evidence for both concordant and discordant associations between cardiovascular disease and PD, discusses the cellular and metabolic processes that may underlie these links, and explores the implications this has for patient care and future research. © 2019 International Parkinson and Movement Disorder Society.

Downregulation of miR-21 suppresses 1-methyl-4-phenylpyridinium-induced neuronal damage in MES23.5 cells

Accumulating evidence suggests that overproduction of oxidative stress, increases neuroinflammation and activates apoptosis. These two processes are associated with the development of Parkinson's disease (PD). The present study aimed to investigate the role of miR-21 in the development of PD. 1-Methyl-4-phenylpyridinium (MPP⁺) was used to induce a PD-like model in MES23.5 cells. The results of the reverse transcription-quantitative PCR assays indicated that miR-21 levels were markedly increased in MES23.5 cells following MPP⁺ treatment. Furthermore, MES23.5 cells were transfected with miR-21 inhibitor, mimics and/or relevant negative control, following MPP⁺ administration. The results of the functional assays revealed that downregulation of miR-21 significantly attenuated the induction of cell apoptosis and reactive oxygen species (ROS) production, while it enhanced the survival of MPP⁺-induced MES23.5 cells. Furthermore, downregulation of miR-21 increased the expression levels of tyrosine hydroxylase, whereas suppression of miR-21 inhibited the production of pro-inflammatory cytokines [interleukin (IL)-6, IL-1β and tumor necrosis factor-α] in MES23.5 cells. Western blot analysis further indicated that the Bcl-2/Bax protein expression ratio was significantly increased and double luciferase assay analysis confirmed that Bcl-2 was a direct target of miR-21. Taken collectively, the data demonstrated that downregulation of miR-21 protected cells from MPP⁺-mediated cytotoxicity by the inhibition of apoptosis induction, the reduction of the inflammatory response and the suppression of ROS production. The present findings may provide novel approaches for PD clinical treatment.

C-Reactive Protein and Risk of Parkinson's Disease: A Systematic Review and Meta-Analysis

Background: C-reactive protein (CRP) has been identified as a common inflammation-related cytokine. Although publications indicate that CRP is associated with the pathogenesis of neurological disorders and deemed to be a "risk factor" for Parkinson's disease (PD), the evidence exists still indefinitely. Here, we performed a systematic review with meta-analysis synthesizing all the eligible studies on serum, plasma, and cerebrospinal fluid (CSF) CRP levels and PD risk to investigate the potential relevance. Methods: A systematical search up to October 2018 was performed via PubMed, Embase, Science Direct, ISI Web of Science as well as three Chinese medical databases: China National Knowledge Infrastructure database (CNKI), VIP database and WanFang database. Risk was assessed by standardized mean difference (SMD) with 95% confidence interval (CI) to investigate the involvement of CRP levels in PD patients. Results: Twenty-three eligible case-control studies involving 4,598 individuals (2,646 PD patients and 1,932 healthy controls) were incorporated into this meta-analysis. Results have indicated significant increase of CRP levels in PD subjects when compared with control groups in serum (SMD = 1.115, 95% CI 0.619-1.61, P < 0.001), CSF (SMD = 1.127, 95% CI 0.133-2.120, P = 0.026) as well as whole blood (SMD = 1.071, 95% CI 0.715-1.426, P < 0.001). Conclusions: This meta-analysis revealed that PD is associated with an increase of CRP levels. CRP might be a risk factor for PD or PD leads to an inflammatory response.

Association between carotid plaque and Parkinson's disease

Background

Epidemiological studies show that patients with Parkinson's disease (PD) are prone to have a reduced incidence of ischemic cerebrovascular disease. Previous studies show the correlation between PD and the lipids serum levels. The PD,s patients are found with a reduced serum level of triglyceride and low-density lipoprotein cholesterol (LDL-C); thus, the level of serum uric acid (UA) is closely related to the occurrence and development of PD. Patients with low serum UA levels have a higher chance of developing PD than the ones who do not. However, the relationship between carotid plaques and PD is still unknown.

Methods

Our study was based on 68 patients with PD (known as the PD group) and 81 people without PD (known as the control group). Patients in the PD group were of the same age and gender. Both groups were recorded and analyzed for UA, LDL-C, and carotid plaques or intima-media thickness (IMT). The PD group was then divided into three subgroups: the stable plaque group, the unstable plaque group, and the non-plaque group.

Results

In the present study, the PD group showed a significantly lower level of UA and LDL-C than the control group (P<0.01); somehow there were no statistically significant differences in the IMT and plaque incidence between the two groups (P>0.05). There were also no significant differences (P>0.05) in both the LDL-C and UA levels in all subgroups, but there was a close relation in both age and duration of disease to IMT. According to the Hoehn and Yahr staging scale, serum levels of LDL-C were inversely correlated in PD patients, while UA was related to the duration of the disease.

Conclusions

Our study suggested that there were no differences in carotid artery arteriosclerosis plaque and IMT, but the PD progress was indeed correlated with IMT. Meanwhile, LDL-C and UA had different priorities in H&Y and disease progression.

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.

Retracted Article: LncRNA MALAT1 aggravates MPP-induced neuronal injury by regulating miR-212 in SH-SY5Y cells

Parkinson's disease (PD) is the most common neurodegenerative disease and its incidence is rising. Long noncoding RNAs (lncRNAs) have been reported to have essential roles in development of PD. LncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) is dysregulated in PD, while the role of MALAT1 and its mechanism in PD remain poorly understood. In this study, SH-SY5Y cells were exposed to 1-methyl-4-phenylpyridinium (MPP+) to induce a PD model in vitro. Then we explored the effect of MALAT1 on cell viability, apoptosis and inflammatory response as well as its interaction with miR-212 in MPP+-treated SH-SY5Y cells. The results showed that MALAT1 was up-regulated in MPP+-treated SH-SY5Y cells compared with that in the normal group. Overexpression of MALAT1 exacerbated MPP+-induced neuronal injury, uncovered by inhibition of cell viability and increase of cell apoptosis as well as inflammatory cytokine expressions in SH-SY5Y cells. However, knockdown of MALAT1 exerted the opposite effect in MPP+-treated SH-SY5Y cells. Moreover, MALAT1 was bound to miR-212 and negatively regulated the miR-212 level. Furthermore, addition of miR-212 ablated the regulatory effect of MALAT1 on MPP+-induced neuronal injury, as indicated by restoration of cell viability and lower apoptotic rate along with inflammatory cytokine levels in SH-SY5Y cells. Therefore, we concluded that MALAT1 exacerbated MPP+-induced neuronal injury through regulating cell viability, apoptosis and inflammatory cytokines by sponging miR-212, providing a novel theoretical foundation for application of MALAT1 in PD.

Systemic Inflammation in Lewy Body Diseases: A Systematic Review

Few studies have investigated the role of inflammation in Lewy body dementia (LBD) and variable results have been found. We systematically reviewed the literature for evidence of systemic inflammatory changes in dementia with Lewy bodies and Parkinson disease dementia. Owing to the low number of studies we also included Parkinson disease. Key terms were used to search the relevant databases. Titles and abstracts were screened and potentially relevant articles were reviewed in full. References of included studies and relevant reviews were searched. The database search returned 2166 results, 46 of which were finally included in the systematic review. These studies showed a general increase in inflammatory markers in the peripheral blood, most notably interleukin-1β (IL-1β), tumor necrosis factor-α, IL-6, and IL-10. Studies examining cerebrospinal fluid found IL-1β, IL-6, and transforming growth factor-β1 to be particularly increased, and interferon-γ decreased. C-reactive protein levels were increased, particularly in Parkinson disease dementia. These results provide evidence that LBD is associated with an increased inflammatory response. Furthermore, there may be a stronger general inflammatory response in LBD than in Parkinson disease, while complex changes occur in the individual cytokines.

The Clinical Significance and Potential Role of C-Reactive Protein in Chronic Inflammatory and Neurodegenerative Diseases

C-reactive protein (CRP) is an acute-phase protein synthesized by hepatocytes in response to pro-inflammatory cytokines during inflammatory/infectious processes. CRP exists in conformationally distinct forms such as the native pentameric CRP and monomeric CRP (mCRP) and may bind to distinct receptors and lipid rafts and exhibit different functional properties. It is known as a biomarker of acute inflammation, but many large-scale prospective studies demonstrate that CRP is also known to be associated with chronic inflammation. This review is focused on discussing the clinical significance of CRP in chronic inflammatory and neurodegenerative diseases, such as cardiovascular disease, type 2 diabetes mellitus, age-related macular degeneration, hemorrhagic stroke, Alzheimer’s disease, and Parkinson’s disease, including recent advances on the implication of CRP and its forms specifically on the pathogenesis of these diseases. Overall, we highlight the advances in these areas that may be translated into promising measures for the diagnosis and treatment of inflammatory diseases.

MiR-212 Attenuates MPP⁺-Induced Neuronal Damage by Targeting KLF4 in SH-SY5Y Cells

PURPOSE

Parkinson's disease (PD) is a common age-dependent neurodegenerative disease. MiR-212 has been demonstrated to exert protective effects in several neurological disorders. The present study aimed to investigate the role and underlying molecular mechanism of miR-212 in PD.

MATERIALS AND METHODS

1-methyl-4-phenylpyridinium (MPP+)-induced SH-SY5Y cells were applied as a PD model in vitro. RT-qPCR was used to measure the expression of miR-212 and Kruppel-like factor 4 (KLF4) mRNA. Western blot analysis was performed to detect the protein levels of KLF4, Notch1 and Jagged1. Cell viability and apoptosis were determined by the Cell Counting Kit-8 and flow cytometry, respectively. Quantitative analysis of caspase-3 activity, lactate dehydrogenase (LDH), reactive oxygen species (ROS), superoxide dismutase (SOD), tumor necrosis factor-α (TNF-α), and interleukin-1 beta (IL-1β) was conducted with corresponding ELISA kits. Dual-luciferase reporter assay was employed to evaluate the relationship between miR-212 and KLF4.

RESULTS

MiR-212 was downregulated in MPP⁺-induced SH-SY5Y cells. Also, miR-212 alleviated MPP⁺-induced SH-SY5Y cell damage, embodied by increased cell viability, decreased caspase-3 activity, LDH release, ROS production, TNF-α, and IL-1β expression, as well as elevated SOD levels. KLF4 was a direct target of miR-212, and miR-212 repressed KLF4 expression in a post-transcriptional manner. Moreover, miR-212-mediated protection effects were abated following KLF4 expression restoration in MPP⁺-induced SH-SY5Y cells, represented as lowered cell viability and enhanced apoptotic rate. Furthermore, Notch signaling was involved in the regulation of miR-212/KLF4 axis in MPP⁺-induced SH-SY5Y cells.

CONCLUSION

miR-212 might attenuate MPP⁺-induced neuronal damage by regulating KLF4/Notch signaling pathway in SH-SY5Y cells, a promising target for PD therapy.

Exposure to particulate matter air pollution and risk of multiple sclerosis in two large cohorts of US nurses

BACKGROUND

Air pollution is thought to raise the risk of neurological disease by promoting neuroinflammation, oxidative stress, glial activation and cerebrovascular damage. Multiple Sclerosis is a common auto-immune disorder, primarily affecting young women. We conducted, to a large prospective study of particulate matter (PM) exposure and multiple sclerosis (MS) risk in two prospective cohorts of women: the Nurses Health Study (NHS) and the Nurses Health Study II (NHS II).

METHODS

Cumulative average exposure to different size fractions of PM up to the onset of MS was estimated using spatio-temporal models. We used multivariable Cox proportional hazards models to estimate the hazard ratios (HR) and 95% confidence intervals (CI) of MS associated with each size fraction of PM independently. Participants were followed from 1998 through 2004 in NHS and from 1988 through 2007 for NHS II. We conducted additional sensitivity analyses stratified by smoking, region of the US, and age, as well as analyses restricted to women who did not move during the study. Analyses were adjusted for age, ancestry, smoking, body mass index at age 18, region, tract level population density, latitude at age 15, and UV index.

RESULTS

We did not observe significant associations between air pollution and MS risk in our cohorts. Among women in the NHS II, the HRs comparing the top vs. bottom quintiles of PM was 1.11 (95% Confidence Intervals (CI): 0.74, 1.66), 1.04 (95% CI: 0.73, 1.50) and 1.09 (95% CI: 0.73, 1.62) for PM₁₀ (≤10μm in diameter), PM_2.5 (≤2.5μm in diameter), and PM_2.5-10 (2.5 to 10μm in diameter) respectively, and tests for linear trends were not statistically significant. No association between exposure to PM and risk of MS was observed in the NHS.

CONCLUSIONS

In this study, exposure to PM air pollution was not related to MS risk.

Lipoic acid alleviates L‑DOPA‑induced dyskinesia in 6‑OHDA parkinsonian rats via anti‑oxidative stress

Levodopa (L‑DOPA) is the gold standard for symptomatic treatment of Parkinson's disease (PD); however, long‑term therapy is associated with the emergence of L‑DOPA‑induced dyskinesia (LID). Nigral dopaminergic cell loss determines the degree of drug exposure and time required for the initial onset of LID. Accumulating evidence indicates that α‑lipoic acid (ALA) decreases this nigral dopaminergic cell loss. However, until now, the precise mechanisms of ALA have only been partially understood in LID. Chronic L‑DOPA treatment was demonstrated to develop intense AIM scores to assess dyskinetic symptoms. Rats in the LID group were administrated twice daily with L‑DOPA + benserazide for 3 weeks to induce a rat model of dyskinesia. Moreover, other 6‑OHDA‑lesioned rats were treatment with ALA (31.5 mg/kg or 63 mg/kg) in combination with L‑DOPA treatment. Furthermore, the authors investigated the level of malondialdehyde (MDA) and glutathione (GSH) activity, as well as IBa‑1, caspase‑3 and poly (ADP-ribose) polymerase (PARP) in substantia nigra by the way of western blotting and immunofluorescence. ALA reduced LID in a dose‑dependent manner without compromising the anti‑PD effect of L‑DOPA. Moreover, ALA reduced the level of MDA and upregulated the GSH activity, as well as ameliorated IBa‑1 positive neurons in the substantia nigra. Finally, it was identified that ALA could reduce L‑DOPA‑induced cleaved‑caspase‑3 and PARP overexpression in the substantia nigra. Based on the present findings, ALA could be recommended as a promising disease‑modifying therapy when administered with L‑DOPA early in the course of PD. The exact mechanism for this action, although incompletely understood, appears to relate to anti‑oxidative stress and anti‑apoptosis.

Air Pollution and Risk of Parkinson's Disease in a Large Prospective Study of Men

BACKGROUND

Exposure to air pollution has been implicated in a number of adverse health outcomes, and the effect of particulate matter (PM) on the brain is beginning to be recognized.

OBJECTIVES

We aimed to examine whether exposure to PM air pollution is related to risk of Parkinson's disease (PD) in the Health Professionals Follow-up Study (HPFS), a large prospective cohort of U.S. men.

METHODS

We prospectively followed 50,352 men in the HPFS, a large prospective cohort of U.S. men, and identified 550 incident PD cases. Cumulative average exposure to various size fractions of PM [PM₁₀ (≤10μm microns in diameter), PM_2.5 (≤2.5μm in diameter), and PM_2.5-10 (between 2.5 and 10μm in diameter)] up to 2 years before the onset of PD was estimated using a spatiotemporal model by linking each participant's place of residence throughout the study with location-specific PM levels. We used multivariable Cox proportional hazards models to independently estimate the risk of PD associated with each size fraction of PM.

RESULTS

In models adjusted for age, smoking, region, and population density, we did not observe statistically significant associations between exposure to PM and PD risk. In analyses considering cumulative average PM exposure, the comparing the top to the bottom quintile of PM exposure was 0.85 [95% confidence interval (CI): (0.63, 1.15)] for PM₁₀, 0.97 [95% CI: (0.72, 1.32)] for PM_2.5, and 0.88 [95% CI: (0.64, 1.22)] for hazard ratio (HR) PM_2.5-10. The results did not change markedly when restricted to men who did not move during the study or when stratified by smoking status or population density.

CONCLUSIONS

In this study, we found no evidence that exposure to air pollution is a risk factor for PD in men. https://doi.org/10.1289/EHP259.

Integrated molecular landscape of Parkinson's disease

Parkinson’s disease is caused by a complex interplay of genetic and environmental factors. Although a number of independent molecular pathways and processes have been associated with familial Parkinson’s disease, a common mechanism underlying especially sporadic Parkinson’s disease is still largely unknown. In order to gain further insight into the etiology of Parkinson’s disease, we here conducted genetic network and literature analyses to integrate the top-ranked findings from thirteen published genome-wide association studies of Parkinson’s disease (involving 13.094 cases and 47.148 controls) and other genes implicated in (familial) Parkinson’s disease, into a molecular interaction landscape. The molecular Parkinson’s disease landscape harbors four main biological processes—oxidative stress response, endosomal-lysosomal functioning, endoplasmic reticulum stress response, and immune response activation—that interact with each other and regulate dopaminergic neuron function and death, the pathological hallmark of Parkinson’s disease. Interestingly, lipids and lipoproteins are functionally involved in and influenced by all these processes, and affect dopaminergic neuron-specific signaling cascades. Furthermore, we validate the Parkinson’s disease -lipid relationship by genome-wide association studies data-based polygenic risk score analyses that indicate a shared genetic risk between lipid/lipoprotein traits and Parkinson’s disease. Taken together, our findings provide novel insights into the molecular pathways underlying the etiology of (sporadic) Parkinson’s disease and highlight a key role for lipids and lipoproteins in Parkinson’s disease pathogenesis, providing important clues for the development of disease-modifying treatments of Parkinson’s disease.

Lipids and lipoproteins play a central role in four key biological processes underlying Parkinson’s disease (PD). Using bioinformatics and other extensive analyses of previously published data, Geert Poelmans, Cornelius Klemann and colleagues in The Netherlands, Germany and the USA have mapped the interactions of proteins that are encoded by genes associated with both familial and sporadic forms of PD. They identify the oxidative stress response, lysosomal function, endoplasmic reticulum stress response and immune response activation as the main mechanisms leading to the death of dopaminergic neurons. Lipid signaling is implicated in all four of these processes and the authors find a link between the levels of particular lipids and lipoproteins and the risk of PD. These findings suggest that compounds that regulate lipid or lipoprotein levels offer a potential new treatment strategy for PD.

NAD+ Supplementation Attenuates Methylmercury Dopaminergic and Mitochondrial Toxicity in Caenorhabditis Elegans

Methylmercury (MeHg) is a neurotoxic contaminant of our fish supply that has been linked to dopaminergic (DAergic) dysfunction that characterizes Parkinson's disease. We have previously shown that MeHg causes both morphological and behavioral changes in the Caenorhabditis elegans DAergic neurons that are associated with oxidative stress. We were therefore interested in whether the redox sensitive cofactor nicotinamide adenine dinucleotide (NAD(+)) may be affected by MeHg and whether supplementation of NAD( + )may prevent MeHg-induced toxicities. Worms treated with MeHg showed depletion in cellular NAD( + )levels, which was prevented by NAD( + )supplementation prior to MeHg treatment. NAD( + )supplementation also prevented DAergic neurodegeneration and deficits in DAergic-dependent behavior upon MeHg exposure. In a mutant worm line that cannot synthesize NAD( + )from nicotinamide, MeHg lethality and DAergic behavioral deficits were more sensitive to MeHg than wildtype worms, demonstrating the importance of NAD( + )in MeHg toxicity. In wildtype worms, NAD( + )supplementation provided protection from MeHg-induced oxidative stress and mitochondrial dysfunction. These data show the importance of NAD( + )levels in the response to MeHg exposure. NAD( + )supplementation may be beneficial for MeHg-induced toxicities and preventing cellular damage involved in Parkinson's disease.

Highly specific changes in antioxidant levels and lipid peroxidation in Parkinson's disease and its progression: Disease and staging biomarkers and new drug targets

There is evidence that immune-inflammatory, stress of reactive oxygen and nitrogen species (IO&NS) processes play a role in the neurodegenerative processes observed in Parkinson's disease (PD). The aim of the present study was to investigate peripheral IO&NS biomarkers in PD. We included 56 healthy individuals and 56 PD patients divided in two groups: early PD stage and late PD stage. Plasma lipid hydroperoxides (LOOH), malondialdehyde (MDA), nitric oxide metabolites (NOx), sulfhydryl (SH) groups, catalase (CAT) activity, superoxide dismutase (SOD) activity, paraoxonase (PON)1 activity, total radical trapping antioxidant parameter (TRAP) and C-reactive protein (CRP) were measured. PD is characterized by increased LOOH, MDA and SOD activity and lowered CAT activity. A combination of five O&NS biomarkers highly significantly predicts PD with a sensitivity of 94.5% and a specificity of 86.8% (i.e., MDA, SOD activity, TRAP, SH-groups and CAT activity). The single best biomarker of PD is MDA, while LOOH and SOD activity are significantly associated with late PD stage, but not early PD stage. Antiparkinson drugs did not affect O&NS biomarkers, but levodopa+carbidopa significantly increased CRP. It is suggested that MDA may serve as a disease biomarker, while LOOH and SOD activity are associated with late PD stage characteristic. New treatments for PD should not only target dopamine but also lipid peroxidation.

Relationship between soluble intercellular adhesion molecules and attention-deficit/hyperactivity disorder

OBJECTIVE

Attention-deficit/hyperactivity disorder (ADHD) is a common childhood-oneset psychiatric disease, characterized by excessive overactivity, inattention, and impulsiveness. In recent studies, it is emphasized that inflammation may have a role in ADHD. In this study, we aimed to investigate whether there are associations between ADHD and serum levels of soluble intercellular adhesion molecules (s-ICAMs) which have important role in inflammatory diseases. We also measured the levels of these molecules after treatment with oros-methylphenidate.

METHODS

Twenty-five patients diagnosed with ADHD according to Diagnostic and Statistical Manual of Mental Disorders-IV-TR criteria and 18 healthy volunteer controls were included in this study. The levels of sICAMs were measured in the serum of the patients and healthy volunteers by ELISA kit as described.

RESULTS

The levels of sICAM-1 and sICAM-2 were significantly higher in patients compared with controls. The level of sICAM-2 was decreased significantly in group treated with oros-methylphenidate.

CONCLUSIONS

This is the first study pointing out the relationship between sICAMs and ADHD. The changes in sICAM-2 level may have a role in the effect mechanism of oros-methylphenidate, used for the treatment of ADHD.

Peripheral administration of the selective inhibitor of soluble tumor necrosis factor (TNF) XPro®1595 attenuates nigral cell loss and glial activation in 6-OHDA hemiparkinsonian rats

BACKGROUND

Parkinson's disease (PD) is a complex multi-system age-related neurodegenerative disorder. Targeting the ongoing neuroinflammation in PD patients is one strategy postulated to slow down or halt disease progression. Proof-of-concept studies from our group demonstrated that selective inhibition of soluble Tumor Necrosis Factor (solTNF) by intranigral delivery of dominant negative TNF (DN-TNF) inhibitors reduced neuroinflammation and nigral dopamine (DA) neuron loss in endotoxin and neurotoxin rat models of nigral degeneration.

OBJECTIVE

As a next step toward human clinical trials, we aimed to determine the extent to which peripherally administered DN-TNF inhibitor XPro®1595 could: i) cross the blood-brain-barrier in therapeutically relevant concentrations, ii) attenuate neuroinflammation (microglia and astrocyte), and iii) mitigate loss of nigral DA neurons in rats receiving a unilateral 6-hydroxydopamine (6-OHDA) striatal lesion.

METHODS

Rats received unilateral 6-OHDA (20 μg into the right striatum). Three or 14 days after lesion, rats were dosed with XPro®1595 (10 mg/kg in saline, subcutaneous) every third day for 35 days. Forelimb asymmetry was used to assess motor deficits after the lesion; brains were harvested 35 days after the lesion for analysis of XPro®1595 levels, glial activation and nigral DA neuron number.

RESULTS

Peripheral subcutaneous dosing of XPro®1595 achieved plasma levels of 1-8 microgram/mL and CSF levels of 1-6 ng/mL depending on the time the rats were killed after final XPro®1595 injection. Irrespective of start date, XPro®1595 significantly reduced microglia and astrocyte number in SNpc whereas loss of nigral DA neurons was attenuated when drug was started 3, but not 14 days after the 6-OHDA lesion.

CONCLUSIONS

Our data suggest that systemically administered XPro®1595 may have disease-modifying potential in PD patients where inflammation is part of their pathology.

Contra-Directional Expression of Serum Homocysteine and Uric Acid as Important Biomarkers of Multiple System Atrophy Severity: A Cross-Sectional Study

HIGHLIGHTS

Serum Hcy was higher in MSA patients when compared to healthy subjects, particularly in male patients.Serum UA was lower in MSA patients when compared healthy subjects, particularly in male patients.Serum Hcy levels were significantly positively correlated with the severity of MSA.The ROC curve for the combination of Hcy and UA showed potential diagnostic value in discriminating MSA from healthy subjects.

AIM

There is evidence suggesting that inflammatory responses play a critical role in the pathogenesis of multiple system atrophy (MSA). Whether inflammatory mediators can be used as reliable biomarkers to detect the severity and progression of MSA remains largely unknown.

METHODS

We performed a cross-sectional study that included 47 patients with MSA and 50 healthy age-matched controls. Serum levels of homocysteine (Hcy), uric acid (UA), and C-reactive protein (CRP) were measured. These levels positively correlated with the severity of MSA, based on both motor and non-motor symptoms. Several scales were used to rate the severity of MSA, including the Unified multiple system atrophy rating scale, Parkinson's disease sleep scale, Non-motor Symptoms Scale, the Schwab & England activities of daily living scale, Webster Scale, modified Hoehn and Yahr staging scale, and the Mini-Mental State Examination. Receiver operating characteristic (ROC) curves was applied to map the diagnostic accuracy of MSA against healthy subjects.

RESULTS

Compared with healthy subjects, we found that serum Hcy was higher, UA was lower, and CRP levels were unchanged in MSA patients. These findings were especially prominent in male patients. No significant differences of serum Hcy and UA were observed between patients of MSA and PD. Interestingly, there was a significant correlation between Hcy levels and MSA severity such as movement dysfunction, declined cognition, and cardiovascular symptoms. Additionally, the ROC curve for the combination of Hcy and UA (AUC 0.736) showed potential diagnostic value in discriminating MSA from healthy subjects.

CONCLUSION

Our findings suggest that the inflammatory mediators Hcy and UA may play important roles in the pathogenesis of MSA. The measurement of serum Hcy and UA levels could then be a useful tool to accurately distinguish MSA from healthy subjects.

Particulate matter and risk of Parkinson disease in a large prospective study of women

BACKGROUND

Exposure to air pollution has been implicated in a number of adverse health outcomes and the effect of particulate matter (PM) on the brain is beginning to be recognized. Yet, no prospective study has examined the association between PM and risk of Parkinson Disease. Thus, our goal was assess if exposure to particulate matter air pollution is related to risk of Parkinson's disease (PD) in the Nurses' Health Study (NHS), a large prospective cohort of women.

METHODS

Cumulative average exposure to different size fractions of PM up to 2 years before the onset of PD, was estimated using a spatio-temporal model by linking each individual's places of residence throughout the study with location-specific air pollution levels. We prospectively followed 115,767 women in the NHS, identified 508 incident PD cases and used multivariable Cox proportional hazards models to estimate the risk of PD associated with each size fraction of PM independently.

RESULTS

In models adjusted for age in months, smoking, region, population density, caffeine and ibuprofen intake, we observed no statistically significant associations between exposure to air pollution and PD risk. The relative risk (RR) comparing the top quartile to the bottom quartile of PM exposure was 0.99 (95% Confidence Intervals (CI): 0.84,1.16) for PM10 (≤10 microns in diameter), 1.08 (95% CI: 0.81, 1.45) for PM2.5 (≤2.5 microns in diameter), and 0.92 (95% CI: 0.71, 1.19) for PM(10-2.5) (2.5 to 10 microns in diameter).

CONCLUSIONS

In this study, we found no evidence that exposure to air pollution is a risk factor for PD.

Molecular Effects of L-dopa Therapy in Parkinson's Disease

Parkinson’s disease (PD) is one of the most common neurological diseases in elderly people. The mean age of onset is 55 years of age, and the risk for developing PD increases 5-fold by the age of 70. In PD, there is impairment in both motor and nonmotor (NMS) functions. The strategy of PD motor dysfunction treatment is simple and generally based on the enhancement of dopaminergic transmission by means of the L-dihydroxyphenylalanine (L-dopa) and dopamine (DA) agonists. L-dopa was discovered in the early -60's of the last century by Hornykiewicz and used for the treatment of patients with PD. L-dopa treatment in PD is related to decreased levels of the neurotransmitter (DA) in striatum and ab-sence of DA transporters on the nerve terminals in the brain. L-dopa may also indirectly stimulate the receptors of the D1 and D2 families. Administration of L-dopa to PD patients, especially long-time therapy, may cause side effects in the form of increased toxicity and inflammatory response, as well as disturbances in biothiols metabolism. Therefore, in PD pa-tients treated with L-dopa, monitoring of oxidative stress markers (8-oxo-2’-deoxyguanosine, apoptotic proteins) and in-flammatory factors (high-sensitivity C-reactive protein, soluble intracellular adhesion molecule), as well as biothiol com-pounds (homocysteine, cysteine, glutathione) is recommended. Administration of vitamins B6, B12, and folates along with an effective therapy with antioxidants and/or anti-inflammatory drugs at an early stage of PD might contribute to improvement in the quality of the life of patients with PD and to slowing down or stopping the progression of the disease.