Levodopa-induced Dyskinesia in Parkinson's Disease: Plausible Inflammatory and Oxidative Stress Biomarkers.

BACKGROUND: Pathophysiology of levodopa-induced dyskinesia (LID) remains obscure. Increased dopamine metabolism due to prolonged levodopa treatment can exacerbate oxidative damage and neuroinflammatory pathology in Parkinson's disease (PD). Association of novel peripheral markers with LID severity might provide insight into LID pathomechanisms. OBJECTIVE: We aimed to study specific peripheral blood inflammatory-oxidative markers in LID patients and investigate their association with clinical severity of LID. METHOD: Motor, non-motor and cognitive changes in PD with and without LID compared to healthy-matched controls were identified. Within the same cohort, inflammatory marker (sLAG3, TOLLIP, NLRP3 and IL-1ß) levels and antioxidant enzyme activities were determined by ELISA and spectrophotometric methods. RESULTS: LID patients showed distinctly upregulated TOLLIP, IL-1ß levels with significant diminution of antioxidant activity compared to controls. Significant negative association of cognitive markers with oxidative changes was also observed. CONCLUSION: To our understanding, this is the first study that indicates the involvement of toll-like receptor-mediated distinct and low-grade inflammatory activation in LID pathophysiology.

Non-Motor Symptoms Assessed by Non-Motor Symptoms Questionnaire and Non-Motor Symptoms Scale in Parkinson's Disease in Selected Asian Populations.

BACKGROUND: Ethnic variations have been described in medical conditions, such as hypertension, diabetes, and multiple sclerosis. Whether ethnicity plays a role in Parkinson's disease (PD), particularly with regard to non-motor symptoms (NMS), remains unclear. Existing literature is diverse, controversial, and inadequately documented. This review aims to analyse and report the currently available literature on NMS, specifically in Asian PD patients. SUMMARY: We conducted a literature review using PubMed, searching for articles and currently available publications that reference and assess NMS in PD patients living in Asia using the validated NMS Questionnaire (NMS Quest) and NMS Scale (NMSS). In total, 24 articles were included: 12 using the NMS Quest and 12 using the NMSS. Symptoms of constipation, memory impairment, and nocturia were the most frequently self-reported symptoms (NMS Quest) in selected Asian populations, while symptoms within the domains sleep/fatigue, attention/memory, and mood/apathy were most prevalent when applying the health-professional completed NMSS. Key Messages: NMS are generally prevalent and highly burdensome within selected Asian PD populations living in countries included in this review. Our review suggests that NMS-driven phenotypic heterogeneity is present in Asian patients, and compared to Western PD populations there might be variations in assessed NMS.

SARM is required for neuronal injury and cytokine production in response to central nervous system viral infection.

Four of the five members of the Toll/IL-1R domain-containing adaptor family are required for signaling downstream of TLRs, promoting innate immune responses against different pathogens. However, the role of the fifth member of this family, sterile α and Toll/IL-1R domain-containing 1 (SARM), is unclear. SARM is expressed primarily in the CNS where it is required for axonal death. Studies in Caenorhabditis elegans have also shown a role for SARM in innate immunity. To clarify the role of mammalian SARM in innate immunity, we infected SARM(-/-) mice with a number of bacterial and viral pathogens. SARM(-/-) mice show normal responses to Listeria monocytogenes, Mycobacterium tuberculosis, and influenza virus, but show dramatic protection from death after CNS infection with vesicular stomatitis virus. Protection correlates with reduced CNS injury and cytokine production by nonhematopoietic cells, suggesting that SARM is a positive regulator of cytokine production. Neurons and microglia are the predominant source of cytokines in vivo, supporting a role for SARM as a link between neuronal injury and innate immunity.

Association of dopamine receptor D3 polymorphism with Levodopa-induced Dyskinesia: A study on Parkinson's disease patients from India.

INTRODUCTION: Levodopa-induced dyskinesia (LID) is a debilitating motor feature in a subset of patients with Parkinson's disease (PD) after prolonged therapeutic administration of levodopa. Preliminary animal and human studies are suggestive of a key role of dopamine type 3 (D3) receptor polymorphism (Ser9Gly; rs6280) in LID. Its contribution to development of LID among Indian PD patients has remained relatively unexplored and merits further investigation. METHODS AND MATERIALS: 200 well-characterised PD patients (100 without LID and 100 with LID) and 100 age-matched healthy controls were recruited from the outpatient department of Institute of Neurosciences Kolkata. MDS-UPDRS (Unified Parkinson's Disease Rating Scale from International Movement Disorder Society) Part III and AIMS (abnormal involuntary movement scale) were performed for estimation of severity of motor features and LID respectively in the ON state of the disease. Participants were analysed for the presence of Ser9Gly single nucleotide variant (SNV) (rs6280) by polymerase chain reaction followed by restriction fragment length polymorphism techniques. RESULTS: The frequency of AA genotype (serine type) was more frequently present in PD patients with LID compared to PD patients without LID (50 % vs 28 %; P = 0.002; OR = 2.57, 95 % CI: 1.43 - 4.62). The abnormal involuntary movement scale score was significantly higher in PD patients with AA genotype compared to carriers of glycine allele (AG + GG) (4.08 ± 3.35; P = 0.002). CONCLUSION: We observed a significant association of serine type SNV (rs6280) in D3 receptor gene in a cohort of PD patients with LID from India. More severe motor severity was found in patients with glycine substitution of the same SNV. The current study emphasised the role of D3 receptor in the pathogenesis of LID.

Characterizing gait and exploring neuro-morphometry in patients with PSP-Richardson's syndrome and vascular parkinsonism.

Gait differentiation in progressive supranuclear palsy (PSP) and vascular parkinsonism (VaP) is sometimes difficult to detect with the naked eye. Here, we compared specific gait parameters, neuro-morphometric indices, and their associations between patients with PSP Richardson's syndrome (PSP-RS) and VaP. A total of 18 PSP-RS and 13 VaP patients were recruited. Spatio-temporal gait parameters (GAITRite®) and neuroanatomical morphometry (FreeSurfer pipeline) were assessed. The groups were compared using unpaired t-tests involving 10000 random permutations after statistically controlling for total UPDRS-III and H&Y scores. Statistically significant differences between the groups were decided at < 5% Benjamini-Hochberg False Discovery Rate (FDR) for multiple-comparison related corrections. Spearman's correlations were performed to assess the significant associations (p < 0.05) between the gait parameters and morphometry indices. Among all the spatio-temporal gait parameters, PSP-RS patients displayed greater stride time, step time, swing time, and stance time variabilities compared to VaP. Morphometric analyses showed that thalamus, and caudate volumes were significantly lower, but cerebellar cortex, hippocampus, amygdala, accumbens, and putamen volumes were higher in PSP-RS than VaP. Moreover, the bilateral insula was significantly thinner in VaP than in PSP-RS. Correlation analyses support the involvement of limbic structures besides cerebellum in postural control during self-paced walking of PSP-RS patients. Our findings underline the importance of examining individual brain regions to understand the association of cortical and subcortical morphometric estimates and gait variability parameters in PSP-RS and VaP. This study suggests the involvement of the limbic system in addition to the classical neural structures for motor control and gait.

Dietary and Environmental Risk Factors in Parkinson's and Alzheimer's Disease: A Semi-Quantitative Pilot Study.

Objective: Environmental influence and dietary variations are well-known risk factors for various diseases including neurodegenerative disorders. Preliminary evidence suggests that diet in early-life and living environment might influence the incidence of Parkinson's disease (PD) in later phase of life. There have been limited epidemiologic studies on this aspect especially in India. In this hospital-based case-control study, we intended to identify dietary and environmental risk factors of PD. Methods: Patients with PD (n = 105), Alzheimer's disease (AD) (n = 53) and healthy individuals (n = 81) were recruited. Dietary intake and environmental exposures were assessed using a validated Food-Frequency and Environmental Hazard Questionnaire. Their demographic details and living environment were also recorded using the same questionnaire. Results: Pre-morbid consumption of carbohydrate and fat was significantly higher whereas dietary fiber and fruit content was significantly lesser in PD as compared to AD and healthy age-matched controls. Meat and milk intake was the highest among all the food groups in PD patients. Rural living and their habitation near water bodies were significantly more frequent in PD patients. Conclusion: We found that past intake of carbohydrate, fat, milk, and meat are associated with increased risk of PD. On the other hand, rural living and habitat near water bodies might be associated with incidence and severity of PD. Hence, preventive strategies related to dietary and environmental modulators in PD might be clinically useful in the future.

Effects of non-invasive vagus nerve stimulation on clinical symptoms and molecular biomarkers in Parkinson's disease.

Non-invasive vagus nerve stimulation (nVNS) is an established neurostimulation therapy used in the treatment of epilepsy, migraine and cluster headache. In this randomized, double-blind, sham-controlled trial we explored the role of nVNS in the treatment of gait and other motor symptoms in Parkinson's disease (PD) patients. In a subgroup of patients, we measured selected neurotrophins, inflammatory markers and markers of oxidative stress in serum. Thirty-three PD patients with freezing of gait (FOG) were randomized to either active nVNS or sham nVNS. After baseline assessments, patients were instructed to deliver six 2 min stimulations (12 min/day) of the active nVNS/sham nVNS device for 1 month at home. Patients were then re-assessed. After a one-month washout period, they were allocated to the alternate treatment arm and the same process was followed. Significant improvements in key gait parameters (speed, stance time and step length) were observed with active nVNS. While serum tumor necrosis factor- α decreased, glutathione and brain-derived neurotrophic factor levels increased significantly (p < 0.05) after active nVNS treatment. Here we present the first evidence of the efficacy and safety of nVNS in the treatment of gait in PD patients, and propose that nVNS can be used as an adjunctive therapy in the management of PD patients, especially those suffering from FOG. Clinical trial registration: identifier ISRCTN14797144.

Novel inflammasome and oxidative modulators in Parkinson's disease: A prospective study.

INTRODUCTION: The etiopathogenesis of Parkinson's disease (PD) is not clear. Yet, it seems likely that inflammation as well as oxidative stress plays a major role in the disease pathogenesis. Based on our previous findings, we aimed to investigate prospective changes in peripheral inflammasome and oxidative modulators in relation to the progression of motor symptoms and severity of PD. METHODS: Levels of inflammatory and oxidative markers in the serum of PD patients and healthy controls were estimated by quantitative ELISA and spectrophotometric methods at the baseline and at the end of one year. RESULTS: In PD patients, serum NLRP3 inflammasome and IL-1ß levels increased significantly over a year, compared to the baseline. The average enzymatic activity of serum SOD1 was also augmented at one-year follow-up. Alongside these serummarker changes, the mean motorseverity of this patient cohort worsened over the time period. CONCLUSION: This pioneering study identified a novel association of peripheral inflammatory and oxidative markers with the progression of PD. Correlation of these serum proteins with the central pathological changes in PD and disease severity in a prospective manner might be useful not only for prognostication, but for understanding disease mechanisms and for planning future therapeutic strategies.

Nigrosome and Neuromelanin Imaging as Tools to Differentiate Parkinson's Disease and Parkinsonism.

Parkinson's disease (PD) lacks a definitive diagnosis due to a lack of pathological validation of patients at antemortem. The risk of misdiagnosis is high in the early stages of PD, often eluded by atypical parkinsonian symptoms. Neuroimaging and laboratory biomarkers are being sought to aid in the clinical diagnosis of PD. Nigrosome imaging and neuromelanin (NM)-sensitive magnetic resonance imaging (MRI) are the new emerging tools, both technically simple plus cost-effective for studying nigral pathology, and have shown potential for authenticating the clinical diagnosis of PD. Visual assessment of the nigrosome-1 appearance, at 3 or 7 Tesla, yields excellent diagnostic accuracy for differentiating idiopathic PD from healthy controls. Moreover, midbrain atrophy and putaminal hypointensity in nigrosome-1 imaging are valid pointers in distinguishing PD from allied parkinsonian disorders. The majority of studies employed T2 and susceptibility-weighted imaging MRI sequences to visualize nigrosome abnormalities, whereas T1-weighted fast-spin echo sequences were used for NM imaging. The diagnostic performance of NM-sensitive MRI in discriminating PD from normal HC can be improved further. Longitudinal studies with adequate sampling of varied uncertain PD cases should be designed to accurately evaluate the sensitivity and diagnostic potential of nigrosome and NM imaging techniques. Equal weightage is to be given to uniformity and standardization of protocols, data analysis, and interpretation of results. There is tremendous scope for identifying disease-specific structural changes in varied forms of parkinsonism with these low-cost imaging tools. Nigrosome-1 and midbrain NM imaging may not only provide an accurate diagnosis of PD but could mature into tools for personally tailored treatment and prognosis.

Is peripheral alpha synuclein a marker for gait velocity in Parkinson's disease?

BACKGROUND: The extent of gait abnormality is non-uniform across motor phenotypes of Parkinson's disease (PD). The biological basis of this heterogeneity remains intriguing. Moreover, the relationship of gait impairment with various neurodegenerative protein markers in PD is not well established. OBJECTIVES: Here, we aimed to explore the interplay between gait parameters and specific serum protein markers in PD. METHODS: A total of 62 PD patients were consecutively recruited. Blood samples and gait data were acquired from 37 and 34 patients respectively. Two-dimensional spatio-temporal gait parameters were estimated using an electronic walkway (GAITRite®, CIR Systems Inc., USA). Serum phosphorylated alpha synuclein (p-Ser129-a-syn) and total a-syn levels were measured using commercially available ELISA kit. Data was analyzed using SPSS Version 20 (IBM). RESULTS: We found that phosphorylated a-syn levels were significantly higher in PD patients with postural instability and gait difficulty compared to tremor dominant variant. Significant reduction in gait velocity was also observed with increasing levels of this pathological form of a-syn. Regression modelling showed that phosphorylated a-syn is an independent predictor of gait velocity. DISCUSSION: Our findings indicate that concentrations of peripheral p-Ser129-a-syn but not total a-syn could be a potential contributor of gait impairment in PD. Further investigation on the systemic role of phosphorylated a-syn on gait would bridge the gap between central and peripheral mechanisms underlying phenotypic variability in PD.

Behavioral deficits and progressive neuropathology in progranulin-deficient mice: a mouse model of frontotemporal dementia.

Progranulin haploinsufficiency causes frontotemporal dementia with tau-negative, ubiquitin-positive neuronal inclusion pathology. In this study, we showed that progranulin-deficient mice displayed increased depression- and disinhibition-like behavior, as well as deficits in social recognition from a relatively young age. These mice did not have any deficit in locomotion or exploration. Eighteen-month-old progranulin-deficient mice demonstrated impaired spatial learning and memory in the Morris water maze. In addition to behavioral deficits, progranulin-deficient mice showed a progressive development of neuropathology from 12 mo of age, including enhanced activation of microglia and astrocytes and ubiquitination and cytoplasmic accumulation of phosphorylated TDP-43. Thus, progranulin deficiency induced FTD-like behavioral and neuropathological deficits. These mice may serve as an important tool for deciphering underlying mechanisms in frontotemporal dementia.

Soluble LAG-3 and Toll-interacting protein: Novel upstream neuro-inflammatory markers in Parkinson's disease.

INTRODUCTION: There is some evidence regarding the role of LAG-3, TLR mediated neuroinflammation in PD. METHODS: sLAG-3, TOLLIP, NLRP3 levels were measured in PD and healthy controls. RESULTS: These markers were significantly higher in PD and were associated with progression. CONCLUSION: sLAG3 and TOLLIP are involved in the NLRP3 mediated inflammatory activation in PD.

Do peripheral immune and neurotrophic markers correlate with motor severity of Parkinson's disease?

BACKGROUND: Inflammation along with oxidative stress alters neuroplasticity which might contribute to neurodegeneration in Parkinson's disease (PD). OBJECTIVES: We aimed to explore the correlation of inflammatory-oxidative and neurotrophic changes in PD and their association with clinical staging and motor severity. METHODS: Serum oxidative markers, pro and anti-inflammatory cytokines and BDNF levels were estimated by spectrophotometric and ELISA techniques. RESULTS: Redox-Inflammatory and neurotrophic markers significantly altered in PD and strongly correlated with motor severity and stagings of PD. CONCLUSION: This study establishes a link between peripheral immune-neurotrophic markers and disease severity in PD. This can lead to novel future therapeutics.

Semantic Fluency Predicts Gait Velocity in PSP.

Context: Progressive supranuclear palsy (PSP) is a large-scale network disease resulting in variable signs and symptoms including gait impairment and higher order cognitive dysfunction. Despite few studies showing the association of falls and cognitive dysfunction, the existing literature is yet to establish the exact relationship of discrete characteristics of gait with cognitive function in PSP. Aims: In this cross-sectional study, we aimed to characterize and explore the relationship of these two apparently distinct physiological phenomena in patients with PSP and across its different variants. Methods and Material: Quantitative assessment of two-dimensional gait parameters was measured using an electronic walkway (GAITRite®). Dementia Rating Scale-2 was used to assess global as well as higher order cognitive functions. Statistical Analysis Used: A regression model was used to interpret results. Results: We observed that the variability domain of gait was significantly impaired in PSP patients with severe cognitive impairment compared to that of intact cognition. Moreover, initiation/perseveration (I/P), a higher order cognitive process, and one of its specific components, i.e., complex verbal task (ß = 2.39, P < 0.001), significantly predict gait velocity in PSP [F (1, 40) = 16.102, P < 0.001]. Conclusions: Our findings indicate that the severity of cognitive functions affects gait variability, which might lead to frequent falls as observed in PSP. Furthermore, semantic fluency task of I/P function may act as a predictor of gait velocity. We suspect that higher order cognitive dysfunction through the damage of frontal lobe structure including dorsolateral prefrontal cortex or related network may influence gait in PSP.

Non-invasive vagus nerve stimulation improves clinical and molecular biomarkers of Parkinson's disease in patients with freezing of gait.

Non-invasive vagus nerve stimulation (nVNS) is an established neurostimulation therapy used in the treatment of epilepsy, migraine and cluster headache. In this randomized, double-blind, sham-controlled crossover trial we explored the role of nVNS in the treatment of gait and other motor symptoms in Parkinson's disease (PD) patients. In a subgroup of patients, we measured selected neurotrophin levels and markers of inflammation and oxidative stress in serum, before and after the experimental intervention. Thirty-three PD patients with associated freezing of gait were randomised to either nVNS or sham. After baseline assessments, patients were instructed to deliver 6 two-minute stimulations (total 12 min/day) of the nVNS/sham device (electroCore, Inc. USA) for one month at home. Patients were then re-assessed. After a washout period of one month, the same patients were allocated to the alternate treatment arm and the same process was followed. Significant improvements in key gait parameters were observed with nVNS, including walking speed, stance time and step length, compared to sham. Similarly, overall motor function (MDS-UPDRS III) also improved significantly following nVNS stimulation. Serum Tumor Necrosis Factor (TNF)-α and glutathione levels decreased and brain-derived neurotrophic factor (BDNF) levels increased significantly (p < 0.05) after treatment with nVNS. Here we present the first double-blind sham-controlled trial evidence of the efficacy and safety of nVNS in the treatment of gait and motor function in patients with PD.

Unexpected lack of hypersensitivity in LRRK2 knock-out mice to MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine).

Mutations in the leucine-rich repeat kinase 2 (LRRK2) gene are the most common known cause of Parkinson's disease (PD). Whether loss of LRRK2 function accounts for neurodegeneration of dopamine neurons in PD is not known, nor is it known whether LRRK2 kinase activity modulates the susceptibility of dopamine (DA) neurons to the selective dopaminergic toxin, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). To better understand the role of LRRK2 in DA neuronal survival and its role in the susceptibility of DA neurons to MPTP, we generated LRRK2 knock-out (KO) mice lacking the kinase domain of LRRK2. Here, we show that LRRK2 KO mice are viable and have no major abnormalities and live to adulthood. The dopaminergic system is normal in LRRK2 KO mice as assessed via HPLC for DA and its metabolites and via stereologic assessment of DA neuron number in young and aged mice. Importantly, there is no significant difference in the susceptibility of LRRK2 KO and wild-type mice to MPTP. These results suggest that LRRK2 plays little if any role in the development and survival of DA neurons under physiologic conditions. Thus, PD due to LRRK2 mutations are likely not due to a loss of function. Moreover, LRRK2 is not required for the susceptibility of DA neurons to MPTP.

Mitochondrial dysfunction in the limelight of Parkinson's disease pathogenesis.

Parkinson's disease (PD) is a progressive neurodegenerative movement disorder with unknown etiology. It is marked by widespread neurodegeneration in the brain with profound loss of A9 midbrain dopaminergic neurons in substantia nigra pars compacta. Several theories of biochemical abnormalities have been linked to pathogenesis of PD of which mitochondrial dysfunction due to an impairment of mitochondrial complex I and subsequent oxidative stress seems to take the center stage in experimental models of PD and in postmortem tissues of sporadic forms of illness. Recent identification of specific gene mutations and their influence on mitochondrial functions has further reinforced the relevance of mitochondrial abnormalities in disease pathogenesis. In both sporadic and familial forms of PD abnormal mitochondrial paradigms associated with disease include impaired functioning of the mitochondrial electron transport chain, aging associated damage to mitochondrial DNA, impaired calcium buffering, and anomalies in mitochondrial morphology and dynamics. Here we provide an overview of specific mitochondrial functions affected in sporadic and familial PD that play a role in disease pathogenesis. We propose to utilize these gained insights to further streamline and focus the research to better understand mitochondria's role in disease development and exploit potential mitochondrial targets for therapeutic interventions in PD pathogenesis.

Inflammasome and α-synuclein in Parkinson's disease: A cross-sectional study.

BACKGROUND: Alpha-synuclein and inflammatory pathology are evident in Parkinson's disease (PD) but, their link to disease pathogenesis needs further elucidation. OBJECTIVES: To explore α-synuclein-mediated inflammation in the serum of PD patients and its link with disease severity. METHODS: Serum levels of IL-1ß, NLRP3, total and phosphorylated α-synuclein were compared. RESULTS: IL-1ß, NLRP3 levels were significantly increased in PD. We also observed a linear correlation of NLRP3 with α-synuclein. Phosphorylated α-synuclein levels were significantly elevated in later stages of PD. CONCLUSIONS: The α-synuclein-NLRP3 mediated inflammation may underline the pathophysiology of PD and might serve as a novel therapeutic target in PD.

Ingress of blood-borne macrophages across the blood-brain barrier in murine HIV-1 encephalitis.

Blood-borne macrophage ingress into brain in HIV-1 associated neurocognitive disorders governs the tempo of disease. We used superparamagnetic iron-oxide particles loaded into murine bone marrow-derived macrophages (BMM) injected intravenously into HIV-1 encephalitis mice to quantitatively assess BMM entry into diseased brain regions. Magnetic resonance imaging tests were validated by histological coregistration and enhanced image processing. The demonstration of robust BMM migration into areas of focal encephalitis provide 'proof of concept' for the use of MRI to monitor macrophage ingress into brain.

Neuroprotective activities of CD4+CD25+ regulatory T cells in an animal model of Parkinson's disease.

Progressive loss of dopaminergic neurons in the substantia nigra pars compacta and their terminal connections in the striatum are central features in Parkinson's disease (PD). Emerging evidence supports the notion that microglia neuroinflammatory responses speed neurodegenerative events. We demonstrated previously that this can be slowed by adoptive transfer of T cells from Copolymer-1-immunized mice administered to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) recipients. The cellular basis for this neuroprotective response was the CD4+ T cell population, suggesting involvement of CD4+CD25+ regulatory T cells (Tregs), cells known to suppress immune activation and maintain immune homeostasis and tolerance. We show for the first time that adoptive transfer of CD3-activated Tregs to MPTP-intoxicated mice provides greater than 90% protection of the nigrostriatal system. The response was dose-dependent and paralleled modulation of microglial responses and up-regulation of glial cell-derived neurotrophic factor (CDNF) and TGF-beta. Interestingly, that adoptive transfer of effector T cells showed no significant neuroprotective activities. Tregs were found to mediate neuroprotection through suppression of microglial responses to stimuli, including aggregated, nitrated alpha-synuclein. Moreover, Treg-mediated suppression was also operative following removal of Tregs from culture prior to stimulation. This neuroprotection was achieved through modulation of microglial oxidative stress and inflammation. As Tregs can be modulated in vivo, these data strongly support the use of such immunomodulatory strategies to treat PD.