Neurodegeneration and Inflammation-An Interesting Interplay in Parkinson's Disease

SIRT1 attenuates neuroinflammation by deacetylating HSPA4 in a mouse model of Parkinson's disease

As a deacetylase, SIRT1 plays essential roles in various physiological events, from development to lifespan regulation. SIRT1 has been shown neuroprotective effects in neurodegeneration disorders such as Parkinson's disease (PD). However, the underlying molecular mechanisms are still not well understood. Here, we generated transgenic mice with increased expression of Sirt1 in the brain and examined the potential roles of SIRT1 in PD. Our data showed that SIRT1 repressed proinflammatory cytokine expression both in microglia and astrocytes. In MPTP induced PD model mice, lower levels of microglia and astrocyte activation were observed in SIRT1 transgenic mice. Moreover, the tyrosine hydroxylase (TH) loss in the substantia nigra pars compacta (SNpc) and striatum induced by MPTP was also attenuated by SIRT1. As a consequence, the behavioral defects induced by MPTP were largely prevented in SIRT1 transgenic mice. Mechanistically, SIRT1 interacts with heat shock 70 kDa protein 4 (HSPA4) and deacetylates it at 305, 351 and 605 lysine residues. This deacetylation modification induces the nuclear translocation of HSPA4 and thus to repress proinflammatory cytokine expression. On the contrary, mutated HSPA4, in which 305/351/605 lysine residues were replaced with arginine, was mainly localized in the cytoplasm and losses its repression on proinflammatory cytokine expression. Taken together, our data indicate that SIRT1 plays beneficial roles in PD model mice, which is likely due to, at least in part, its anti-inflammation activity in glial cells by deacetylating HSPA4. Furthermore, HSPA4 might be a druggable target for developing novel agents for treating neuroinflammation associated disorders such as PD.

Myelin-associated oligodendrocyte basic protein rs616147 polymorphism as a risk factor for Parkinson's disease

BACKGROUND

The rs616147 polymorphism of the myelin-associated oligodendrocyte basic protein (MOBP) gene locus has been associated with amyotrophic lateral sclerosis (ALS). ALS and Parkinson's disease (PD) are two common neurodegenerative disorders that share features regarding their etiology, pathophysiology, and genetic backgrounds. While the MOBP rs616147 polymorphism has been associated with ALS, little is known about its role in PD.

OBJECTIVE

To assess the role of MOBP rs616147 on PD risk.

METHODS

This case-control comparison study consists of 358 PD-affected cases and 358 controls from the Neurology Clinic of the University Hospital of Larissa, University of Thessaly, Faculty of Medicine, in Greece. The diagnosis of PD was made by a specialist neurologist according to the UK Parkinson's Disease Society Brain Bank's clinical criteria. All the participants were genotyped for the MOBP rs616147. Furthermore, in order to validate our results, we genotyped 327 patients with Alzheimer's disease (AD) for MOBP rs616147 and compared them with the control group.

RESULTS

According to the univariate analysis, there was a significant association between rs616147 and PD in the dominant (OR [95% C.I.] = 0.70 [0.52-0.94], p = .018), the overdominant (OR [95% C.I.] = 0.68 [0.50-0.92], p = .011), and in the codominant (G/A VS G/G; OR [95% C.I.] = 0.66 [0.48-0.91], p = .035) modes of inheritance. In contrast, there was no association between the MOBP rs616147 polymorphism and AD.

CONCLUSIONS

We provide preliminary results associating MOBP rs616147 genetic variant with PD.

Environmental Impact on the Epigenetic Mechanisms Underlying Parkinson’s Disease Pathogenesis: A Narrative Review

Parkinson’s disease (PD) is the second most common neurodegenerative disorder with an unclear etiology and no disease-modifying treatment to date. PD is considered a multifactorial disease, since both genetic and environmental factors contribute to its pathogenesis, although the molecular mechanisms linking these two key disease modifiers remain obscure. In this context, epigenetic mechanisms that alter gene expression without affecting the DNA sequence through DNA methylation, histone post-transcriptional modifications, and non-coding RNAs may represent the key mediators of the genetic–environmental interactions underlying PD pathogenesis. Environmental exposures may cause chemical alterations in several cellular functions, including gene expression. Emerging evidence has highlighted that smoking, coffee consumption, pesticide exposure, and heavy metals (manganese, arsenic, lead, etc.) may potentially affect the risk of PD development at least partially via epigenetic modifications. Herein, we discuss recent accumulating pre-clinical and clinical evidence of the impact of lifestyle and environmental factors on the epigenetic mechanisms underlying PD development, aiming to shed more light on the pathogenesis and stimulate future research.

Gut-Brain Axis as a Pathological and Therapeutic Target for Neurodegenerative Disorders

Human lifestyle and dietary behaviors contribute to disease onset and progression. Neurodegenerative diseases (NDDs), considered multifactorial disorders, have been associated with changes in the gut microbiome. NDDs display pathologies that alter brain functions with a tendency to worsen over time. NDDs are a worldwide health problem; in the US alone, 12 million Americans will suffer from NDDs by 2030. While etiology may vary, the gut microbiome serves as a key element underlying NDD development and prognosis. In particular, an inflammation-associated microbiome plagues NDDs. Conversely, sequestration of this inflammatory microbiome by a correction in the dysbiotic state of the gut may render therapeutic effects on NDDs. To this end, treatment with short-chain fatty acid-producing bacteria, the main metabolites responsible for maintaining gut homeostasis, ameliorates the inflammatory microbiome. This intimate pathological link between the gut and NDDs suggests that the gut-brain axis (GBA) acts as an underexplored area for developing therapies for NDDs. Traditionally, the classification of NDDs depends on their clinical presentation, mostly manifesting as extrapyramidal and pyramidal movement disorders, with neuropathological evaluation at autopsy as the gold standard for diagnosis. In this review, we highlight the evolving notion that GBA stands as an equally sensitive pathological marker of NDDs, particularly in Alzheimer's disease, Parkinson's disease, amyotrophic lateral sclerosis and chronic stroke. Additionally, GBA represents a potent therapeutic target for treating NDDs.

Are We What We Eat? Impact of Diet on the Gut-Brain Axis in Parkinson's Disease

Parkinson’s disease is characterized by motor and non-motor symptoms, such as defects in the gut function, which may occur before the motor symptoms. To date, there are therapies that can improve these symptoms, but there is no cure to avoid the development or exacerbation of this disorder. Dysbiosis of gut microbiota could have a crucial role in the gut–brain axis, which is a bidirectional communication between the central nervous system and the enteric nervous system. Diet can affect the microbiota composition, impacting gut–brain axis functionality. Gut microbiome restoration through probiotics, prebiotics, synbiotics or other dietary means could have the potential to slow PD progression. In this review, we will discuss the influence of diet on the bidirectional communication between gut and brain, thus supporting the hypothesis that this disorder could begin in the gut. We also focus on how food-based therapies might then have an influence on PD and could ameliorate non-motor as well as motor symptoms.

Dengue Virus Infection and Risk of Parkinson's Disease: A Nationwide Longitudinal Study

Background: Increasing evidence suggests a potential relationship between viral infection and Parkinson’s disease (PD). Objective: Herein, we explore the association between infection by dengue virus and PD. Methods: Between 1997 and 2012, we recruited 1,422 patients with dengue fever and 14,220 matched controls (age, sex, time of enrollment, and medical and mental comorbidities) from the Taiwan National Health Insurance Research Database. We identified new onset of PD to the end of 2013. The Kaplan-Meier method was used to estimate the incidence rate of PD. Cox-regression analysis was applied to calculate the hazard ratios (HRs) with 95% confidence intervals (CIs) after adjustment for confounders. Results: During the follow up period, the dengue group had higher incidence of PD than the control group (1.2% vs. 0.4% , p = 0.001). Patients with dengue fever had a significantly higher risk of developing PD [HR, 2.59; 95% CI, 1.51–4.44] compared with the controls, after adjustments for demographic data, PD-related comorbidities, and all-cause clinical visits. The subgroup analysis, stratified by age and sex, found that higher risk for PD was statistically significant for male (HR, 3.51; 95% CI, 1.76–7.00) and patients aged >60 years (HR, 2.96; 95% CI, 1.62–5.41). Conclusion: The risk of PD was 2.59-fold higher in patients with dengue fever than in non-infected controls during the follow-up period. Clinicians need to monitor signs of PD during patient recovery from dengue fever. Additional studies are needed to confirm our results and investigate the mechanisms linking PD and dengue virus infection.

Therapeutic Strategies for Immune Transformation in Parkinson's Disease

Dysregulation of innate and adaptive immunity can lead to alpha-synuclein (α-syn) misfolding, aggregation, and post-translational modifications in Parkinson's disease (PD). This process is driven by neuroinflammation and oxidative stress, which can contribute to the release of neurotoxic oligomers that facilitate dopaminergic neurodegeneration. Strategies that promote vaccines and antibodies target the clearance of misfolded, modified α-syn, while gene therapy approaches propose to deliver intracellular single chain nanobodies to mitigate α-syn misfolding, or to deliver neurotrophic factors that support neuronal viability in an otherwise neurotoxic environment. Additionally, transformative immune responses provide potential targets for PD therapeutics. Anti-inflammatory drugs represent one strategy that principally affects innate immunity. Considerable research efforts have focused on transforming the balance of pro-inflammatory effector T cells (Teffs) to favor regulatory T cell (Treg) activity, which aims to attenuate neuroinflammation and support reparative and neurotrophic homeostasis. This approach serves to control innate microglial neurotoxic activities and may facilitate clearance of α-syn aggregates accordingly. More recently, changes in the intestinal microbiome have been shown to alter the gut-immune-brain axis leading to suppressed leakage of bacterial products that can promote peripheral inflammation and α-syn misfolding. Together, each of the approaches serves to interdict chronic inflammation associated with disordered immunity and neurodegeneration. Herein, we examine research strategies aimed at improving clinical outcomes in PD.

Role of the Cholinergic Anti-Inflammatory Reflex in Central Nervous System Diseases

In several central nervous system diseases, it has been reported that inflammation may be related to the etiologic process, therefore, therapeutic strategies are being implemented to control inflammation. As the nervous system and the immune system maintain close bidirectional communication in physiological and pathological conditions, the modulation of inflammation through the cholinergic anti-inflammatory reflex has been proposed. In this review, we summarized the evidence supporting chemical stimulation with cholinergic agonists and vagus nerve stimulation as therapeutic strategies in the treatment of various central nervous system pathologies, and their effect on inflammation.

Cognition, motor symptoms, and glycolipid metabolism in Parkinson's disease with depressive symptoms

Depressive symptoms and abnormal glycolipid metabolisms are common in patients with Parkinson's disease (PD), but their relationship has not been fully reported. It is not clear whether glycolipid impairments lead to poor cognitive and motor function, and aggravate depressive symptoms. Therefore, we aimed to explore the relationships between glycolipid variables, cognition, motor and depressive symptoms in PD patients cross-sectionally. Two hundred ten PD patients were recruited. Glycolipid parameters and Uric acid (UA) were measured. Depressive symptoms, cognitive function and motor symptoms were assessed using the Hamilton Depression Rating Scale-17 (HAMD-17), the Montreal Cognitive Assessment (MOCA) and the Movement Disorder Society Unified Parkinson's Disease Rating Scale Part-III (UPDRS-III). Depressive PD patients had significantly worse motor symptoms and higher levels of fasting plasma glucose (FPG) than those in non-depressive patients (F = 24.145, P < 0.001). Further, logistic regression analysis indicated that UPDRS-III (OR = 1.039, 95% CI 1.019-1.057, P = 0.044), FPG (OR = 1.447, 95% CI 1.050-1.994, P = 0.024) were independently associated with depression. In PD patients without depression, UA (β = - 0.068, t = - 2.913, P = 0.005) and cholesterol (CHOL) (β = - 3.941, t = - 2.518, P = 0.014) were independent predictors of the UPDRS-III score; in addition, UPDRS-III score was negatively associated with MOCA score (β = - 0.092, t = - 2.791, P = 0.007). FPG levels and motor symptoms were related to depressive symptoms in PD patients. Further, in non-depressive PD patients, UA and CHOL showed putative biomarkers of motor symptoms.

Alpha-Synuclein Induced Immune Cells Activation and Associated Therapy in Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disorder closely related to immunity. An important aspect of the pathogenesis of PD is the interaction between α-synuclein and a series of immune cells. Studies have shown that accumulation of α-synuclein can induce an autoimmune response that accelerates the progression of PD. This study discusses the mechanisms underlying the interaction between α-synuclein and the immune system. During the development of PD, abnormally accumulated α-synuclein becomes an autoimmune antigen that binds to Toll-like receptors (TLRs) that activate microglia, which differentiate into the microglia type 1 (M1) subtype. The microglia activate intracellular inflammatory pathways, induce the release of proinflammatory cytokines, and promote the differentiation of cluster of differentiation 4 + (CD4 +) T cells into proinflammatory T helper type 1 (Th1) and T helper type 17 (Th17) subtypes. Given the important role of α-synuclein in the immune system of the patients with PD, identifying potential targets of immunotherapy related to α-synuclein is critical for slowing disease progression. An enhanced understanding of immune-associated mechanisms in PD can guide the development of associated therapeutic strategies in the future.

The Emerging Scenario of the Gut-Brain Axis: The Therapeutic Actions of the New Actor Kefir against Neurodegenerative Diseases

The fact that millions of people worldwide suffer from Alzheimer’s disease (AD) or Parkinson’s disease (PD), the two most prevalent neurodegenerative diseases (NDs), has been a permanent challenge to science. New tools were developed over the past two decades and were immediately incorporated into routines in many laboratories, but the most valuable scientific contribution was the “waking up” of the gut microbiota. Disturbances in the gut microbiota, such as an imbalance in the beneficial/pathogenic effects and a decrease in diversity, can result in the passage of undesired chemicals and cells to the systemic circulation. Recently, the potential effect of probiotics on restoring/preserving the microbiota was also evaluated regarding important metabolite and vitamin production, pathogen exclusion, immune system maturation, and intestinal mucosal barrier integrity. Therefore, the focus of the present review is to discuss the available data and conclude what has been accomplished over the past two decades. This perspective fosters program development of the next steps that are necessary to obtain confirmation through clinical trials on the magnitude of the effects of kefir in large samples.

The etiopathogenetic and pathophysiological spectrum of parkinsonism

Parkinsonism is a syndrome characterized by bradykinesia, rigidity, and tremor. Parkinsonism is a common manifestation of Parkinson's disease and other neurodegenerative diseases referred to as atypical parkinsonism. However, a growing body of clinical and scientific evidence indicates that parkinsonism may be part of the phenomenological spectrum of various neurological conditions to a greater degree than expected by chance. These include neurodegenerative conditions not traditionally classified as movement disorders, e.g., dementia and motor neuron diseases. In addition, parkinsonism may characterize a wide range of central nervous system diseases, e.g., autoimmune diseases, infectious diseases, cerebrospinal fluid disorders (e.g., normal pressure hydrocephalus), cerebrovascular diseases, and other conditions. Several pathophysiological mechanisms have been identified in Parkinson's disease and atypical parkinsonism. Conversely, it is not entirely clear to what extent the same mechanisms and key brain areas are also involved in parkinsonism due to a broader etiopathogenetic spectrum. We aimed to provide a comprehensive and up-to-date overview of the various etiopathogenetic and pathophysiological mechanisms of parkinsonism in a wide spectrum of neurological conditions, with a particular focus on the role of the basal ganglia involvement. The paper also highlights potential implications in the diagnostic approach and therapeutic management of patients. This article is part of the Special Issue "Parkinsonism across the spectrum of movement disorders and beyond" edited by Joseph Jankovic, Daniel D. Truong and Matteo Bologna.

Dysregulation of the Adaptive Immune System in Patients With Early-Stage Parkinson Disease

Objective

To determine the activation status and cytokine profiles of CD4⁺ T cells, CD8⁺ T cells, and CD19⁺ B cells from patients with early-stage Parkinson disease (PD) compared with healthy controls (HCs).

Methods

Peripheral blood samples from 41 patients with early-stage PD and 40 HCs were evaluated. Peripheral blood mononuclear cells were analyzed by flow cytometry for surface markers and intracellular cytokine production. Correlations of immunologic changes and clinical parameters were analyzed.

Results

Adaptive immunity plays a role in the pathogenesis of PD, yet the contribution of T cells and B cells, especially cytokine production by these cells, is poorly understood. We demonstrate that naive CD4⁺ and naive CD8⁺ T cells are significantly decreased in patients with PD, whereas central memory CD4⁺ T cells are significantly increased in patients with PD. Furthermore, IL-17–producing CD4⁺ Th17 cells, IL-4–producing CD4⁺ Th2 cells, and IFN-γ–producing CD8⁺ T cells are significantly increased in patients with PD. Regarding B cells, we observed a decrease in naive B cells and an increase in nonswitched memory and double-negative B cells. As well, TNF-α–producing CD19⁺ B cells were significantly increased in patients with PD. Notably, some of the changes observed in CD4⁺ T cells and B cells were associated with clinical motor disease severity.

Conclusions

These findings suggest that alterations in the adaptive immune system may promote clinical disease in PD by skewing to a more proinflammatory state in the early-stage PD patient cohort. Our study may shed light on potential immunotherapies targeting dysregulated CD4⁺ T cells, CD8⁺ T cells, and CD19⁺ B cells in patients with PD.

JKAP relates to disease risk, severity, and Th1 and Th17 differentiation in Parkinson's disease

Objective

JNK pathway‐associated phosphatase (JKAP) is previously reported to regulate immune/inflammatory process via T‐cell signaling, and closely involves in neurological diseases, while its implication in Parkinson's disease (PD) is unknown. Therefore, this study aimed to investigate the correlation of JKAP with Th1/Th2/Th17 cells and their clinical roles in PD patients, and then further explore the effect of JKAP on regulating CD4⁺ T‐cell differentiation in PD.

Methods

Totally 50 PD patients and 50 age‐/gender‐matched controls were enrolled. Their blood samples were collected and proposed to ELISA and flow cytometry assays for JKAP, Th1, Th2, and Th17 measurements. In vitro, CD4⁺ T cells were isolated from PD patients then transfected with JKAP overexpression and knockdown Lentivirus, followed by detection of markers (CD25⁺ cell proportion, CD69⁺ cell proportion, IFN‐γ, IL10, and IL17).

Results

JKAP was downregulated in PD patients compared to controls, which also showed good potency to discriminate them. Besides, JKAP negatively correlated with Th1 and Th17 cell proportions, but did not associate with Th2 cell proportion in PD patients; Interestingly, JKAP did not correlated with Th1, Th2, or Th17 cell proportions in controls. Furthermore, JKAP correlated with some parts of unified Parkinson’s Disease Rating Scale (UPDRS) and Mini‐Mental State Examination (MMSE) score. In vitro, JKAP overexpression repressed CD4⁺ T‐cell activation and its differentiation into Th1 and Th17 cells in PD, while JKAP knockdown appeared opposite effect.

Interpretation

JKAP associates with disease risk and severity, correlates with Th1 and Th17 cells, and regulates CD4⁺ T‐cell activation/differentiation in PD.

Possible Link between SARS-CoV-2 Infection and Parkinson's Disease: The Role of Toll-Like Receptor 4

Parkinson's disease (PD) is the most common neurodegenerative motor disorder characterized by selective degeneration of dopaminergic neurons in the substantia nigra pars compacta (SNpc) of the midbrain, depletion of dopamine (DA), and impaired nigrostriatal pathway. The pathological hallmark of PD includes the aggregation and accumulation α-synuclein (α-SYN). Although the precise mechanisms underlying the pathogenesis of PD are still unknown, the activation of toll-like receptors (TLRs), mainly TLR4 and subsequent neuroinflammatory immune response, seem to play a significant role. Mounting evidence suggests that viral infection can concur with the precipitation of PD or parkinsonism. The recently identified coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of ongoing pandemic coronavirus disease 2019 (COVID-19), responsible for 160 million cases that led to the death of more than three million individuals worldwide. Studies have reported that many patients with COVID-19 display several neurological manifestations, including acute cerebrovascular diseases, conscious disturbance, and typical motor and non-motor symptoms accompanying PD. In this review, the neurotropic potential of SARS-CoV-2 and its possible involvement in the pathogenesis of PD are discussed. Specifically, the involvement of the TLR4 signaling pathway in mediating the virus entry, as well as the massive immune and inflammatory response in COVID-19 patients is explored. The binding of SARS-CoV-2 spike (S) protein to TLR4 and the possible interaction between SARS-CoV-2 and α-SYN as contributing factors to neuronal death are also considered.

Data-driven biomarker analysis using computational omics approaches to assess neurodegenerative disease progression

The complexity of biological systems suggests that current definitions of molecular dysfunctions are essential distinctions of a complex phenotype. This is well seen in neurodegenerative diseases (ND), such as Alzheimer's disease (AD) and Parkinson's disease (PD), multi-factorial pathologies characterized by high heterogeneity. These challenges make it necessary to understand the effectiveness of candidate biomarkers for early diagnosis, as well as to obtain a comprehensive mapping of how selective treatment alters the progression of the disorder. A large number of computational methods have been developed to explain network-based approaches by integrating individual components for modeling a complex system. In this review, high-throughput omics methodologies are presented for the identification of potent biomarkers associated with AD and PD pathogenesis as well as for monitoring the response of dysfunctional molecular pathways incorporating multilevel clinical information. In addition, principles for efficient data analysis pipelines are being discussed that can help address current limitations during the experimental process by increasing the reproducibility of benchmarking studies.

Neuroprotective and Anti-Inflammatory Effects of Evernic Acid in an MPTP-Induced Parkinson's Disease Model

Oxidative stress, mitochondrial dysfunction, and neuroinflammation are strongly associated with the pathogenesis of Parkinson's disease (PD), which suggests that anti-oxidative and anti-inflammatory compounds might provide an alternative treatment for PD. Here, we evaluated the neuroprotective effects of evernic aid (EA), which was screened from a lichen library provided by the Korean Lichen Research Institute at Sunchon National University. EA is a secondary metabolite generated by lichens, including Ramalina, Evernia, and Hypogymnia, and several studies have described its anticancer, antifungal, and antimicrobial effects. However, the neuroprotective effects of EA have not been studied. We found that EA protected primary cultured neurons against 1-methyl-4-phenylpyridium (MPP+)-induced cell death, mitochondrial dysfunction, and oxidative stress, and effectively reduced MPP+-induced astroglial activation by inhibiting the NF-κB pathway. In vivo, EA ameliorated MPTP-induced motor dysfunction, dopaminergic neuronal loss, and neuroinflammation in the nigrostriatal pathway in C57BL/6 mice. Taken together, our findings demonstrate that EA has neuroprotective and anti-inflammatory effects in PD models and suggest that EA is a potential therapeutic candidate for PD.

MicroRNA-3473b regulates the expression of TREM2/ULK1 and inhibits autophagy in inflammatory pathogenesis of Parkinson disease

Parkinson disease (PD) is a neurodegenerative disease characterized by selective loss of dopaminergic (DA) neurons in the midbrain. The regulatory role of a variety of microRNAs in PD has been confirmed, and our study is the first to demonstrate that miR-3473b is involved in the regulation of PD. In vitro, an miR-3473b inhibitor can inhibit the secretion of inflammatory factors (TNF-α and IL-1β) in moues microglia cell line (BV2) cells induced by lipopolysaccharide (LPS) and promote autophagy in BV2 cells. In vivo, miR-3473b antagomir can inhibit the activation of substantia nigra pars compacta (SNpc) microglia of C57BL/6 mice induced by 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) and promote autophagy. Deletion of TREM2, one of the most highly expressed receptors in microglia, leads to the occurrence and development of PD. ULK1 is a component of the Atg1 complex. Deletion of ULK1 aggravates the pathological reaction of PD. TREM2 and ULK1 are predicted potential targets of miR-3473b by Targetscan. Then, the results of our experiments indicate that transfection with a miR-3473b mimic can inhibit the expression of TREM2 and ULK1. Data from a double luciferase experiment indicate that the 3'-UTR of TREM2, but not ULK1, is the direct target of miR-3473b. Then we aim to investigate the regulation of TREM2 and ULK1 in PD. We found that the expression of p-ULK1 was significantly increased via up-regulation of TREM2. The increased expression of p-ULK1 can promote autophagy and inhibit the expression of inflammatory factors. The regulation of ULK1 by miR-3473b may be accomplished indirectly through TREM2. Thus, miR-3473b may regulate the secretion of proinflammatory mediators by targeting TREM2/ULK1 expression to regulate the role of autophagy in the pathogenesis of inflammation in Parkinson's disease, suggesting that mir-3473b may be a potential therapeutic target to regulate the inflammatory response in PD.