The role of inflammation in sporadic and familial Parkinson's disease

SARS-CoV-2 Infection and Alpha-Synucleinopathies: Potential Links and Underlying Mechanisms

Alpha-synuclein (α-syn) is a 140-amino-acid, intrinsically disordered, soluble protein that is abundantly present in the brain. It plays a crucial role in maintaining cellular structures and organelle functions, particularly in supporting synaptic plasticity and regulating neurotransmitter turnover. However, for reasons not yet fully understood, α-syn can lose its physiological role and begin to aggregate. This altered α-syn disrupts dopaminergic transmission and causes both presynaptic and postsynaptic dysfunction, ultimately leading to cell death. A group of neurodegenerative diseases known as α-synucleinopathies is characterized by the intracellular accumulation of α-syn deposits in specific neuronal and glial cells within certain brain regions. In addition to Parkinson's disease (PD), these conditions include dementia with Lewy bodies (DLBs), multiple system atrophy (MSA), pure autonomic failure (PAF), and REM sleep behavior disorder (RBD). Given that these disorders are associated with α-syn-related neuroinflammation-and considering that SARS-CoV-2 infection has been shown to affect the nervous system, with COVID-19 patients experiencing neurological symptoms-it has been proposed that COVID-19 may contribute to neurodegeneration in PD and other α-synucleinopathies by promoting α-syn misfolding and aggregation. In this review, we focus on whether SARS-CoV-2 could act as an environmental trigger that facilitates the onset or progression of α-synucleinopathies. Specifically, we present new evidence on the potential role of SARS-CoV-2 in modulating α-syn function and discuss the causal relationship between SARS-CoV-2 infection and the development of parkinsonism-like symptoms.

Emerging perspectives on precision therapy for Parkinson's disease: multidimensional evidence leading to a new breakthrough in personalized medicine

PD is a prevalent and progressive neurodegenerative disorder characterized by both motor and non-motor symptoms. Genes play a significant role in the onset and progression of the disease. While the complexity and pleiotropy of gene expression networks have posed challenges for gene-targeted therapies, numerous pathways of gene variant expression show promise as therapeutic targets in preclinical studies, with some already in clinical trials. With the recognition of the numerous genes and complex pathways that can influence PD, it may be possible to take a novel approach to choose a treatment for the condition. This approach would be based on the symptoms, genomics, and underlying mechanisms of the disease. We discuss the utilization of emerging genetic and pathological knowledge of PD patients to categorize the disease into subgroups. Our long-term objective is to generate new insights for the therapeutic approach to the disease, aiming to delay and treat it more effectively, and ultimately reduce the burden on individuals and society.

SARS-CoV-2 Spike Protein 1 Causes Aggregation of α-Synuclein via Microglia-Induced Inflammation and Production of Mitochondrial ROS: Potential Therapeutic Applications of Metformin

Abnormal aggregation of α-synuclein is the hallmark of neurodegenerative diseases, classified as α-synucleinopathies, primarily occurring sporadically. Their onset is associated with an interaction between genetic susceptibility and environmental factors such as neurotoxins, oxidative stress, inflammation, and viral infections. Recently, evidence has suggested an association between neurological complications in long COVID (sometimes referred to as 'post-acute sequelae of COVID-19') and α-synucleinopathies, but its underlying mechanisms are not completely understood. In this study, we first showed that SARS-CoV-2 Spike protein 1 (S1) induces α-synuclein aggregation associated with activation of microglial cells in the rodent model. In vitro, we demonstrated that S1 increases aggregation of α-synuclein in BE(2)M-17 dopaminergic neurons via BV-2 microglia-mediated inflammatory responses. We also identified that S1 directly affects aggregation of α-synuclein in dopaminergic neurons through increasing mitochondrial ROS, though only under conditions of sufficient α-Syn accumulation. In addition, we observed a synergistic effect between S1 and the neurotoxin MPP+ S1 treatment. Combined with a low dose of MPP+, it boosted α-synuclein aggregation and mitochondrial ROS production compared to S1 or the MPP+ treatment group. Furthermore, we evaluated the therapeutic effects of metformin. The treatment of metformin suppressed the S1-induced inflammatory response and α-synucleinopathy. Our findings demonstrate that S1 promotes α-synucleinopathy via both microglia-mediated inflammation and mitochondrial ROS, and they provide pathological insights, as well as a foundation for the clinical management of α-synucleinopathies and the onset of neurological symptoms after the COVID-19 outbreak.

Functional connectivity in autism spectrum disorder evaluated using rs-fMRI and DKI

We evaluated functional connectivity (FC) in patients with adult autism spectrum disorder (ASD) using resting-state functional MRI (rs-fMRI) and diffusion kurtosis imaging (DKI). We acquired rs-fMRI data from 33 individuals with ASD and 33 healthy controls (HC) and DKI data from 18 individuals with ASD and 17 HC. ASD showed attenuated FC between the right frontal pole (FP) and the bilateral temporal fusiform cortex (TFusC) and enhanced FC between the right thalamus and the bilateral inferior division of lateral occipital cortex, and between the cerebellar vermis and the right occipital fusiform gyrus (OFusG) and the right lingual gyrus, compared with HC. ASD demonstrated increased axial kurtosis (AK) and mean kurtosis (MK) in white matter (WM) tracts, including the right anterior corona radiata (ACR), forceps minor (FM), and right superior longitudinal fasciculus (SLF). In ASD, there was also a significant negative correlation between MK and FC between the cerebellar vermis and the right OFusG in the corpus callosum, FM, right SLF and right ACR. Increased DKI metrics might represent neuroinflammation, increased complexity, or disrupted WM tissue integrity that alters long-distance connectivity. Nonetheless, protective or compensating adaptations of inflammation might lead to more abundant glial cells and cytokine activation effectively alleviating the degeneration of neurons, resulting in increased complexity. FC abnormality in ASD observed in rs-fMRI may be attributed to microstructural alterations of the commissural and long-range association tracts in WM as indicated by DKI.

HMGB1 Mediates Inflammation-Induced DMT1 Increase and Dopaminergic Neurodegeneration in the Early Stage of Parkinsonism

Both neuroinflammation and iron accumulation play roles in the pathogenesis of Parkinson's disease (PD). However, whether inflammation induces iron dyshomeostasis in dopaminergic neurons at an early stage of PD, at which no quantifiable dopaminergic neuron loss can be observed, is still unknown. As for the inflammation mediators, although several cytokines have been reported to increase in PD, the functions of these cytokines in the SN are double-edged and controversial. In this study, whether inflammation could induce iron dyshomeostasis in dopaminergic neurons through high mobility group protein B1 (HMGB1) in the early stage of PD is explored. Lipopolysaccharide (LPS), a toxin that primarily activates glia cells, and 6-hydroxydopamine (6-OHDA), the neurotoxin that firstly impacts dopaminergic neurons, were utilized to mimic PD in rats. We found a common and exceedingly early over-production of HMGB1, followed by an increase of divalent metal transporter 1 with iron responsive element (DMT1+) in the dopaminergic neurons before quantifiable neuronal loss. HMGB1 neutralizing antibody suppressed inflammation in the SN, DMT1+ elevation in dopaminergic neurons, and dopaminergic neuronal loss in both LPS and 6-OHDA administration- induced PD models. On the contrary, interleukin-1β inhibitor diacerein failed to suppress these outcomes induced by 6-OHDA. Our findings not only demonstrate that inflammation could be one of the causes of DMT1+ increase in dopaminergic neurons, but also highlight HMGB1 as a pivotal early mediator of inflammation-induced iron increase and subsequent neurodegeneration, thereby HMGB1 could serve as a potential target for early-stage PD treatment.

Banxia-Houpu decoction inhibits iron overload and chronic intermittent hypoxia-induced neuroinflammation in mice

ETHNOPHARMACOLOGICAL RELEVANCE

The Banxia-Houpu decoction (BHD), a renowned prescription documented in the Chinese medical book "The Synopsis of the Golden Chamber," has been proven to effectively mitigate inflammation within the central nervous system. Previous studies have demonstrated the efficacy of BHD in ameliorating symptoms in patients with obstructive sleep apnea (OSA). Nevertheless, the precise mechanisms and comprehensive effects of BHD on central system injury in OSA models have not been fully investigated.

AIM OF THE STUDY

To investigate whether BHD could inhibit neuroinflammation to decrease iron-induced neurotoxic injury in CIH mice.

MATERIALS AND METHODS

C57BL/6N mice were divided into the Con, CIH, and BHD groups. Mice were exposed to CIH (21%-5% FiO2, 3 min/cycle, 8 h/d), and BHD was administered by gavage (3.51, 7.01, and 14.02 g/kg). The polarization of microglia, inflammatory factors, hepcidin, and brain iron levels were determined.

RESULTS

The administration of BHD at a dosage of 7.01 g/kg demonstrated a significant reduction in neurobehavioral abnormalities, neuronal damage, and degeneration caused by CIH. BHD exhibited the ability to inhibit the transition of microglial polarization from M2 to M1 by upregulating CD163 expression and downregulating iNOS levels. Furthermore, BHD decreased pro-inflammatory factor levels and increased anti-inflammatory factor levels. Additionally, BHD was found to decrease hepcidin expression in astrocytes through the TLR4/MyD88/NF-κB signaling pathway. BHD reduced the total and neuronal iron levels by elevating FPN1 and reducing TfR1 levels. BHD exhibited positive effects on synapse and synaptic spine abnormalities, as well as an increase in the Bcl-2/Bax ratio, thereby mitigating neuronal damage induced by CIH.

CONCLUSIONS

Based on these findings, BHD holds potential as a therapeutic intervention for neural damage injuries, which offers a theoretical foundation for the treatment of patients with OSA in clinical.

Effect of Ganglioside combined with pramexol in the treatment of Parkinson's disease and its effect on motor function

Background

This study was aimed to evaluate the efficacy of pramipexole combined with ganglioside for PD treatment and pramipexole monotherapy, so as to provide reference for clinical practice.

Methods

61 PD patients selected from June 2019 to December 2020 at our hospital were divided into two groups. The control group (n=31) was given dopasizide oral treatment, and the treatment group (n=30) was given ganglioside combined with pramipexole. The clinical efficacy, adverse reactions, motor function scores, UPDRS scores, PDQ-39 scale scores, TNF-a levels, and related serum factor levels were measured in this study.

The applied value in brain gray matter nuclei of patients with early-stage Parkinson's disease : a study based on multiple magnetic resonance imaging techniques

PURPOSE

This study compares the observation efficiency of brain gray matter nuclei of patients with early-stage Parkinson's disease among various Magnetic Resonance Imaging techniques, which include susceptibility weighted imaging (SWI), quantitative susceptibility imaging (QSM), diffusion tensor imaging (DTI) and diffusion kurtosis imaging (DKI). Based on the findings, this study suggests an efficient combination of scanning techniques for brain gray matter nuclei observation, aiming to provide an opportunity to advance the understanding of clinical diagnosis of early-stage Parkinson's disease.

METHODS

Forty examinees, including twenty patients who were clinically diagnosed with early Parkinson's disease with a course of 0.5-6 years (PD group) and twenty healthy controls (HC group), underwent head MRI examination. Philips 3.0T (tesla) MR machine was used to measure the imaging indexes of gray matter nuclei in patients with early Parkinson's disease. SWI, QSM, DTI and DKI were used for diagnosis. SPSS (Statistical Product and Service Solutions) 21.0 was used for data analysis.

RESULTS

When SWI was used, fifteen PD patients and six healthy volunteers were diagnosed correctly. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic coincidence rate about the diagnosis of nigrosome-1 on imaging were 75.0%, 30.0%, 51.7%, 54.5% and 52.5% respectively. By contrast, when QSM was used, 19 PD patients and 11 healthy volunteers were diagnosed correctly. The sensitivity, specificity, positive predictive value, negative predictive value and diagnostic coincidence rate about the diagnosis of Nigrosome-one on imaging were 95.0%, 55.0%, 67.9%, 91.7% and 75.0% respectively. The mean kurtosis (MK) value within both the substantia nigra and thalamus, together with the mean diffusivity (MD) within both the substantia nigra and the head of caudate nucleus in PD group was greater than that of HC group. The susceptibility values within the substantia nigra, red nucleus, head of caudate nucleus and putamen of PD group was greater than that of HC group. The MD value in substantia nigra reveals the optimal diagnostic efficiency to distinguish the HC group and the PD group, followed by the MK value in substantia nigra. Specifically, the maximum area under ROC curve (AUC) of the MD value was 0.823, the sensitivity 70.0%, the specificity 85.0%, and the diagnostic threshold 0.414. The area under ROC curve (AUC) of the MK value was 0.695, the sensitivity 95.0%, the specificity 50.0%, and the diagnostic threshold was 0.667. Both of them were statistically significant.

CONCLUSIONS

In the early diagnosis of Parkinson's disease, QSM is more efficient than SWI in observing nigrosome-1 in substantia nigra. In the early diagnosis of Parkinson's disease, MD and MK values of substantia nigra in DKI parameters have higher diagnostic efficiency. The combined scanning of DKI and QSM has the highest diagnostic efficiency and provides imaging basis for clinical diagnosis of early Parkinson's disease.

Proof-of-Principle Study of Inflammasome Signaling Proteins as Diagnostic Biomarkers of the Inflammatory Response in Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disorder marked by the death of dopaminergic neurons in the midbrain, the accumulation of α-synuclein aggregates, and motor deficits. A major contributor to dopaminergic neuronal loss is neuroinflammation. The inflammasome is a multiprotein complex that perpetuates neuroinflammation in neurodegenerative disorders including PD. Increases in inflammasome proteins are associated with worsened pathology. Thus, the inhibition of inflammatory mediators has the potential to aid in PD treatment. Here, we investigated inflammasome signaling proteins as potential biomarkers of the inflammatory response in PD. Plasma from PD subjects and healthy age-matched controls were evaluated for levels of the inflammasome protein apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC), caspase-1, and interleukin (IL)-18. This was carried out using Simple Plex technology to identify changes in inflammasome proteins in the blood of PD subjects. The area under the curve (AUC) was obtained through calculation of the receiver operating characteristics (ROC) to obtain information on biomarker reliability and traits. Additionally, we completed a stepwise regression selected from the lowest Akaike information criterion (AIC) to assess how the inflammasome proteins caspase-1 and ASC contribute to IL-18 levels in people with PD. PD subjects demonstrated elevated caspase-1, ASC, and IL-18 levels when compared to controls; each of these proteins were found to be promising biomarkers of inflammation in PD. Furthermore, inflammasome proteins were determined to significantly contribute to and predict IL-18 levels in subjects with PD. Thus, we demonstrated that inflammasome proteins serve as reliable biomarkers of inflammation in PD and that inflammasome proteins provide significant contributions to IL-18 levels in PD.

Neurodegeneration and inflammation crosstalk: Therapeutic targets and perspectives

Glia, which was formerly considered to exist just to connect neurons, now plays a key function in a wide range of physiological events, including formation of memory, learning, neuroplasticity, synaptic plasticity, energy consumption, and homeostasis of ions. Glial cells regulate the brain's immune responses and confers nutritional and structural aid to neurons, making them an important player in a broad range of neurological disorders. Alzheimer's, ALS, Parkinson's, frontotemporal dementia (FTD), and epilepsy are a few of the neurodegenerative diseases that have been linked to microglia and astroglia cells, in particular. Synapse growth is aided by glial cell activity, and this activity has an effect on neuronal signalling. Each glial malfunction in diverse neurodegenerative diseases is distinct, and we will discuss its significance in the progression of the illness, as well as its potential for future treatment.

Impact of Sex on Neuroimmune contributions to Parkinson's disease

Parkinson's disease (PD) is the second most common neurodegenerative disorder after Alzheimer's disease. Inflammation has been observed in both the idiopathic and familial forms of PD. Importantly, PD is reported more often in men than in women, men having at least 1.5- fold higher risk to develop PD than women. This review summarizes the impact of biological sex and sex hormones on the neuroimmune contributions to PD and its investigation in animal models of PD. Innate and peripheral immune systems participate in the brain neuroinflammation of PD patients and is reproduced in neurotoxin, genetic and alpha-synuclein based models of PD. Microglia and astrocytes are the main cells of the innate immune system in the central nervous system and are the first to react to restore homeostasis in the brain. Analysis of serum immunoprofiles in female and male control and PD patients show that a great proportion of these markers differ between male and female. The relationship between CSF inflammatory markers and PD clinical characteristics or PD biomarkers shows sex differences. Conversely, in animal models of PD, sex differences in inflammation are well documented and the beneficial effects of endogenous and exogenous estrogenic modulation in inflammation have been reported. Targeting neuroinflammation in PD is an emerging therapeutic option but gonadal drugs have not yet been investigated in this respect, thus offering new opportunities for sex specific treatments.

An Update on Peripheral Blood Extracellular Vesicles as Biomarkers for Parkinson's Disease Diagnosis

Parkinson's disease (PD) is the world's second primary neurodegenerative disease, and the diagnosis and treatment of PD have become mainstream research. Over the past decades, several studies have identified potential biomarkers for diagnosing PD. Among them, extracellular vesicles (EVs) can carry specific biomarkers reflecting the physiological and pathological state of the body. Due to the blood-brain barrier (BBB) limitation, peripheral blood is limited in diagnosing neurodegenerative diseases. With the increasing research on EVs, their ability to pass through BBB indicated that peripheral blood could depict disease status like cerebrospinal fluid (CSF). Peripheral blood is a clinically available sample and has recently been widely used by researchers in various studies. In this review, we summarized previous studies on PD diagnosis biomarkers in peripheral blood EVs and evaluated their diagnostic value. Some EV surface markers were also described, which can extract EVs from specific cell origins. In addition, the combination of several biomarkers demonstrated good diagnostic performance in PD diagnosis compared with a single biomarker, suggesting the focus of future research.

The CXCL12/CXCR4/ACKR3 Response Axis in Chronic Neurodegenerative Disorders of the Central Nervous System: Therapeutic Target and Biomarker

There has been an increase in the incidence of chronic neurodegenerative disorders of the central nervous system, including Alzheimer's and Parkinson's diseases, over the recent years mostly due to the rise in the number of elderly individuals. In addition, various neurodegenerative disorders are related to imbalances in the CXCL12/CXCR4/ACKR3 response axis. Notably, the CXC Chemokine Ligand 12 (CXCL12) is essential for the development of the central nervous system. Moreover, the expression and distribution of CXCL12 and its receptors are associated with the aggravation or alleviation of symptoms of neurodegenerative disorders. Therefore, the current review sought to highlight the specific functions of CXCL12 and its receptors in various neurodegenerative disorders, in order to provide new insights for future research.

The Innate and Adaptive Immune Cells in Alzheimer’s and Parkinson’s Diseases

Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common neurodegenerative disorders of the central nervous system (CNS). Increasing evidence supports the view that dysfunction of innate immune cells initiated by accumulated and misfolded proteins plays essential roles in the pathogenesis and progression of these diseases. The TLR family was found to be involved in the regulation of microglial function in the pathogenesis and progression of AD or PD, making it as double-edged sword in these diseases. Altered function of peripheral innate immune cells was found in AD and PD and thus contributed to the development and progression of AD and PD. Alteration of different subsets of T cells was found in the peripheral blood and CNS in AD and PD. The CNS-infiltrating T cells can exert both neuroprotective and neurotoxic effects in the pathogenesis and progression. Here, we review recent evidences for the roles of innate and adaptive immune cells in the pathogenesis and progression of AD and PD.

Single-cell RNA sequencing of CSF reveals neuroprotective RAC1+ NK cells in Parkinson’s disease

Brain infiltration of the natural killer (NK) cells has been observed in several neurodegenerative disorders, including Parkinson’s disease (PD). In a mouse model of α-synucleinopathy, it has been shown that NK cells help in clearing α-synuclein (α-syn) aggregates. This study aimed to investigate the molecular mechanisms underlying the brain infiltration of NK cells in PD. Immunofluorescence assay was performed using the anti-NKp46 antibody to detect NK cells in the brain of PD model mice. Next, we analyzed the publicly available single-cell RNA sequencing (scRNA-seq) data (GSE141578) of the cerebrospinal fluid (CSF) from patients with PD to characterize the CSF immune landscape in PD. Results showed that NK cells infiltrate the substantia nigra (SN) of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD model mice and colocalize with dopaminergic neurons and α-syn. Moreover, the ratio of NK cells was found to be increased in the CSF of PD patients. Analysis of the scRNA-seq data revealed that Rac family small GTPase 1 (RAC1) was the most significantly upregulated gene in NK cells from PD patients. Furthermore, genes involved in regulating SN development were enriched in RAC1⁺ NK cells and these cells showed increased brain infiltration in MPTP-induced PD mice. In conclusion, NK cells actively home to the SN of PD model mice and RAC1 might be involved in regulating this process. Moreover, RAC1⁺ NK cells play a neuroprotective role in PD.

Nutrition and Gut–Brain Pathways Impacting the Onset of Parkinson’s Disease

An emerging body of literature suggests that long-term gut inflammation may be a silent driver of Parkinson’s disease (PD) pathogenesis. Importantly, specific nutritive patterns might improve gut health for PD risk reduction. Here, we review the current literature on the nutritive patterns and inflammatory markers as a predictor for early detection of PD. This knowledge might be used to foster the detection of early nutritive patterns and preclinical biomarkers to potentially alter PD development and progression.

Effects of Compounds Isolated from Lindera erythrocarpa on Anti-Inflammatory and Anti-Neuroinflammatory Action in BV2 Microglia and RAW264.7 Macrophage

Lindera erythrocarpa contains various constituents such as cyclopentenedione-, flavonoid-, and chalcone-type components. In this study, a novel bi-linderone derivative and 17 known compounds were isolated from the leaves of L. erythrocarpa by using various chromatographic methods. The structures of the components were determined from nuclear magnetic resonance and mass spectrometry data. All isolated compounds were tested for anti-inflammatory and anti-neuroinflammatory activities in lipopolysaccharide (LPS)-induced BV2 and RAW264.7 cells. Some of these compounds showed anti-inflammatory effects by inhibiting the nitric oxide (NO) produced by LPS. In particular, linderaspirone A (16), bi-linderone (17) and novel compound demethoxy-bi-linderone (18) showed significant inhibitory effects on the production of prostaglandin E2 (PGE₂), tumor necrosis factor-α, and interleukin-6. The three compounds also inhibited the expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2), which are pro-inflammatory proteins, and the activation of nuclear factor κB (NF-κB). Therefore, linderaspirone A (16), bi-linderone (17), and demethoxy-bi-linderone (18) isolated from the leaves of L. erythrocarpa have therapeutic potential in neuroinflammatory diseases.

DAT and TH expression marks human Parkinson's disease in peripheral immune cells

Parkinson's disease (PD) is marked by a loss of dopamine neurons, decreased dopamine transporter (DAT) and tyrosine hydroxylase (TH) expression. However, this validation approach cannot be used for diagnostic, drug effectiveness or investigational purposes in human patients because midbrain tissue is accessible postmortem. PD pathology affects both the central nervous and peripheral immune systems. Therefore, we immunophenotyped blood samples of PD patients for the presence of myeloid derived suppressor cells (MDSCs) and discovered that DAT+/TH+ monocytic MDSCs, but not granulocytic MDSCs are increased, suggesting a targeted immune response to PD. Because in peripheral immune cells DAT activity underlies an immune suppressive mechanism, we investigated whether expression levels of DAT and TH in the peripheral immune cells marks PD. We found drug naïve PD patients exhibit differential DAT+/TH+ expression in peripheral blood mononuclear cells (PBMCs) compared to aged/sex matched healthy subjects. While total PBMCs are not different between the groups, the percentage of DAT+/TH+ PBMCs was significantly higher in drug naïve PD patients compared to healthy controls irrespective of age, gender, disease duration, disease severity or treatment type. Importantly, treatment for PD negatively modulates DAT+/TH+ expressing PBMCs. Neither total nor the percentage of DAT+/TH+ PBMCs were altered in the Alzheimer's disease cohort. The mechanistic underpinning of this discovery in human PD was revealed when these findings were recapitulated in animal models of PD. The reverse translational experimental strategy revealed that alterations in dopaminergic markers in peripheral immune cells are due to the disease associated changes in the CNS. Our study demonstrates that the dopaminergic machinery on peripheral immune cells displays an association with human PD, with exciting implications in facilitating diagnosis and investigation of human PD pathophysiology.

Polydatin as a therapeutic alternative for central nervous system disorders: A systematic review of animal studies

Polydatin, or piceid, is a natural stilbene found in grapes, peanuts, and wines. Polydatin presents pharmacological activities, including neuroprotective properties, exerting preventive and/or therapeutic effects in central nervous system (CNS) disorders. In the present study, we summarize and discuss the neuroprotective effects of polydatin in CNS disorders and related pathological conditions in preclinical animal studies. A systematic review was performed by searching online databases, returning a total of 110 records, where 27 articles were selected and discussed here. The included studies showed neuroprotective effects of polydatin in experimental models of neurological disorders, including cerebrovascular disorders, Parkinson's disease, traumatic brain injuries, diabetic neuropathy, glioblastoma, and neurotoxicity induced by chemical agents. Most studies were focused on stroke (22.2%) and conducted in male rodents. The intervention protocol with polydatin was mainly acute (66.7%), with postdamage induction treatment being the most commonly used regimen (55.2%). Overall, polydatin ameliorated behavioral dysfunctions and/or promoted neurological function by virtue of its antioxidant and antiinflammatory properties. In summary, this review offers important scientific evidence for the neuroprotective effects and distinct pharmacological mechanisms of polydatin that not only enhances the present understanding but is also useful for the development of future preclinical and clinical investigations.

Parkinson's disease peripheral immune biomarker profile: a multicentre, cross-sectional and longitudinal study

BACKGROUND

Inflammations play crucial role in the pathogenesis of Parkinson's disease (PD), however, their possible value in the diagnosis or tracking of the progress of PD is still limited, because of discordant results in the literature and a lack of information regarding its reproducibility. Thus, overall longitudinal and cross-sectional studies are needed. This multicentre study was designed to investigate the association between multiple peripheral immune biomarkers and the development and progression of PD.

METHODS

This was a longitudinal and multicentre study. First, we measured the levels of five typical cytokines and five focused chemokines in 76 PD patients and 76 healthy controls (HCs) in a discovery cohort. Then, a validation cohort of 80 PD and 80 HC participants was recruited from four multicentre locations. In addition, a prospective follow-up of early-stage PD patients was performed with significant biomarkers. Finally, we performed further verification in an exploratory set of patients with idiopathic REM sleep behaviour disorder (iRBD).

RESULTS

In the discovery set, CXCL12, CX3CL1 and IL-8 levels were significantly higher in PD patients than in HCs (p < 0.05). The receiver-operating characteristic (ROC) curve for a combination of these three biomarkers produced a high area under the curve (AUC) of 0.89 (p < 0.001). Moreover, four biomarkers (the previous three and CCL15) were significantly associated with PD in the discovery and validation cohorts. Furthermore, in the prospective follow-up cohort, CX3CL1 levels were associated with motor progression after a mean interval of 43 months. In addition, CX3CL1 and IL-8 levels were higher in iRBD patients than in HCs.

CONCLUSION

We showed a correlation between a profile of four peripheral immune biomarkers and PD development and progression. Our findings may provide a basis whereby PD patients with abnormal inflammatory profiles can be identified and receive timely therapeutic interventions.

Pyroptosis in neurodegenerative diseases: What lies beneath the tip of the iceberg?

Neurodegenerative diseases gradually receive attention with a rapidly aging global population. The hallmark of them is a progressive neuronal loss in the brain or peripheral nervous system due to complex reasons ranging from protein aggregation, immune dysregulation to abnormal cell death. The death style of nerve cell is no longer restricted to apoptosis, autophagy and necrosis as confirmed before. With the successive discoveries of the gasdermin (GSDM) protein family and key caspase molecules in the past several decades, pyroptosis emerges as a novel kind of programmed cell death. A substantial body of evidence has recognized the close connection between pyroptosis and the occurrence and development of neurodegenerative diseases. In this review, we summarize molecular mechanisms of pyroptosis, evidences for pyroptosis involvement in neurodegenerative diseases and finally we hope to provide a novel angle for clinical decision-making.

Mutant LRRK2 in lymphocytes regulates neurodegeneration via IL-6 in an inflammatory model of Parkinson's disease

Mutations in a number of genes contribute to development of Parkinson’s disease (PD), including several within the LRRK2 gene. However, little is known about the signals that underlie LRRK2-mediated neuronal loss. One clue resides in the finding that the neurodegenerative cascades emanate from signals arising from the peripheral immune system. Here, using two chimeric mouse models, we demonstrate that: 1) the replacement of mutant LRRK2 with wt form of the protein in T- and B-lymphocytes diminishes LPS-mediated inflammation and rescues the SNpc DA neuron loss in the mutant LRRK2 brain; 2) the presence of G2019S or R1441G LRRK2 mutation in lymphocytes alone is sufficient for LPS-induced DA neuron loss in the genotypically wt brain; and 3) neutralization of peripheral IL-6 overproduction prevents the SNpc DA neuron loss in LPS-treated mutant LRRK2 mice. These results represent a major paradigm shift in our understanding of PD pathogenesis and suggest that immune dysfunction in some forms of familial PD may have primacy over the CNS as the initiating site of the disorder.

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.

Dapsone, More than an Effective Neuro and Cytoprotective Drug

BACKGROUND

Dapsone (4,4'-diamino-diphenyl sulfone) is a synthetic derivative of sulfones, with the antimicrobial activity described since 1937. It is also a drug traditionally used in dermatological therapies due to its anti-inflammatory effect. In recent years its antioxidant, antiexcitotoxic, and antiapoptotic effects have been described in different ischemic damage models, traumatic damage, and models of neurodegenerative diseases, such as Parkinson's (PD) and Alzheimer's diseases (AD). Finally, dapsone has proven to be a safe and effective drug as a protector against heart, renal and pulmonary cells damage; that is why it is now employed in clinical trials with patients as a neuroprotective therapy by regulating the main mechanisms of damage that lead to cell death ObjectiveThe objective of this study is to provide a descriptive review of the evidence demonstrating the safety and therapeutic benefit of dapsone treatment, evaluated in animal studies and various human clinical trials Methods: We conducted a review of PubMed databases looking for scientific research in animals and humans, oriented to demonstrate the effect of dapsone on regulating and reducing the main mechanisms of damage that lead to cell death ConclusionThe evidence presented in this review shows that dapsone is a safe and effective neuro and cytoprotective treatment that should be considered for translational therapy.

TNFα increases tyrosine hydroxylase expression in human monocytes

Most, if not all, peripheral immune cells in humans and animals express tyrosine hydroxylase (TH), the rate limiting enzyme in catecholamine synthesis. Since TH is typically studied in the context of brain catecholamine signaling, little is known about changes in TH production and function in peripheral immune cells. This knowledge gap is due, in part, to the lack of an adequately sensitive assay to measure TH in immune cells expressing lower TH levels compared to other TH expressing cells. Here, we report the development of a highly sensitive and reproducible Bio-ELISA to quantify picogram levels of TH in multiple model systems. We have applied this assay to monocytes isolated from blood of persons with Parkinson's disease (PD) and to age-matched, healthy controls. Our study unexpectedly revealed that PD patients' monocytes express significantly higher levels of TH protein in peripheral monocytes relative to healthy controls. Tumor necrosis factor (TNFα), a pro-inflammatory cytokine, has also been shown to be increased in the brains and peripheral circulation in human PD, as well as in animal models of PD. Therefore, we investigated a possible connection between higher levels of TH protein and the known increase in circulating TNFα in PD. Monocytes isolated from healthy donors were treated with TNFα or with TNFα in the presence of an inhibitor. Tissue plasminogen activator (TPA) was used as a positive control. We observed that TNFα stimulation increased both the number of TH+ monocytes and the quantity of TH per monocyte, without increasing the total numbers of monocytes. These results revealed that TNFα could potentially modify monocytic TH production and serve a regulatory role in peripheral immune function. The development and application of a highly sensitive assay to quantify TH in both human and animal cells will provide a novel tool for further investigating possible PD immune regulatory pathways between brain and periphery.

Neuroinflammation: An Integrating Overview of Reactive-Neuroimmune Cell Interactions in Health and Disease

The concept of central nervous system (CNS) inflammation has evolved over the last decades. Neuroinflammation is the response of reactive CNS components to altered homeostasis, regardless of the cause to be endogenous or exogenous. Neurological diseases, whether traumatic, neoplastic, ischemic, metabolic, toxic, infectious, autoimmune, developmental, or degenerative, involve direct and indirect immune-related neuroinflammation. Brain infiltrates of the innate and adaptive immune system cells appear in response to an infective or otherwise noxious agent and produce inflammatory mediators. Mediators of inflammation include local and recruited cells and signals. Processes derived from extrinsic and intrinsic CNS diseases also elicit the CNS inflammatory response. A deeper understanding of immune-related inflammation in health and disease is necessary to find potential therapeutic targets for preventing or reducing CNS damage. This review is aimed at discussing the innate and adaptive immune system functions and their roles in regulating brain cell responses in disease and homeostasis maintenance.

Back to the future: lessons from past viral infections and the link with Parkinson's disease

During the current coronavirus disease 2019 (COVID-19) pandemic, there has been noticeable increase in the reporting of neurological symptoms in patients. There is still uncertainty around the significance and long-term consequence of these symptoms. There are also many outstanding questions on whether the causative virus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) can directly infect the central nervous system (CNS). Given the long association between viral infections with neurodegenerative conditions such as Parkinson's disease (PD), it seems timely to review this literature again in the context of the COVID-19 pandemic and to glean some useful information from studies on similar viruses. In this commentary, we will consider the current knowledge on viral infections in the brain. In addition, we review the link between viral infection and neurodegeneration in PD, and review the recent literature on SARS infections, the potential link with PD and the potential areas of study in the future.

Anti-Apoptotic and Anti-Inflammatory Role of Trans ε-Viniferin in a Neuron-Glia Co-Culture Cellular Model of Parkinson's Disease

The polyphenol trans-ε-viniferin (viniferin) is a dimer of resveratrol, reported to hold antioxidant and anti-inflammatory properties. The aims of our study were to evaluate the neuroprotective potential of viniferin in the nerve growth factor (NGF)-differentiated PC12 cells, a dopaminergic cellular model of Parkinson's disease (PD) and assess its anti-inflammatory properties in a N9 microglia-neuronal PC12 cell co-culture system. The neuronal cells were pre-treated with viniferin, resveratrol or their mixture before the administration of 6-hydroxydopamine (6-OHDA), recognized to induce parkinsonism in rats. Furthermore, N9 microglia cells, in a co-culture system with neuronal PC12, were pre-treated with viniferin, resveratrol or their mixture to investigate whether these polyphenols could reduce lipopolysaccharide (LPS)-induced inflammation. Our results show that viniferin as well as a mixture of viniferin and resveratrol protects neuronal dopaminergic cells from 6-OHDA-induced cytotoxicity and apoptosis. Furthermore, when viniferin, resveratrol or their mixture was used to pre-treat microglia cells in our co-culture system, they reduced neuronal cytotoxicity induced by glial activation. Altogether, our data highlight a novel role for viniferin as a neuroprotective and anti-inflammatory molecule in a dopaminergic cellular model, paving the way for nutraceutical therapeutic avenues in the complementary treatments of PD.

Neuroprotective Effects of a GLP-2 Analogue in the MPTP Parkinson's Disease Mouse Model

BACKGROUND

Glucagon-like peptide 2 (GLP-2) is a peptide hormone derived from the proglucagon gene expressed in the intestines, pancreas and brain. Some previous studies showed that GLP-2 improved aging and Alzheimer's disease related memory impairments. Parkinson's disease (PD) is a progressive neurodegenerative disorder, and to date, there is no particular medicine reversed PD symptoms effectively.

OBJECTIVE

The aim of this study was to evaluate neuroprotective effects of a GLP-2 analogue in the 1-Methyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (MPTP) PD mouse model.

METHODS

In the present study, the protease resistant Gly(2)-GLP-2 (50 nmol/kg ip.) analogue has been tested for 14 days by behavioral assessment, transmission electron microscope, immunofluorescence histochemistry, enzyme-linked immunosorbent assay and western blot in an acute PD mouse model induced by MPTP. For comparison, the incretin receptor dual agonist DA5-CH was tested in a separate group.

RESULTS

The GLP-2 analogue treatment improved the locomotor and exploratory activity of mice, and improved bradykinesia and movement imbalance of mice. Gly(2)-GLP-2 treatment also protected dopaminergic neurons and restored tyrosine hydroxylase expression levels in the substantia nigra. Gly(2)-GLP-2 furthermore reduced the inflammation response as seen in lower microglia activation, and decreased NLRP3 and interleukin-1β pro-inflammatory cytokine expression levels. In addition, the GLP-2 analogue improved MPTP-induced mitochondrial dysfunction in the substantia nigra. The protective effects were comparable to those of the dual agonist DA5-CH.

CONCLUSION

The present results demonstrate that Gly(2)-GLP-2 can attenuate NLRP3 inflammasome-mediated inflammation and mitochondrial damage in the substantia nigra induced by MPTP, and Gly(2)-GLP-2 shows neuroprotective effects in this PD animal model.

Histamine-4 receptor antagonist ameliorates Parkinson-like pathology in the striatum

Growing evidence indicates that microglia activation and a neuroinflammatory trigger contribute to dopaminergic cell loss in Parkinson's disease (PD). Furthermore, increased density of histaminergic fibers and enhanced histamine levels have been observed in the substantia nigra of PD-postmortem brains. Histamine-induced microglial activation is mediated by the histamine-4 receptor (H4R). In the current study, gene set enrichment and pathway analyses of a PD basal ganglia RNA-sequencing dataset revealed that upregulation of H4R was in the top functional category for PD treatment targets. Interestingly, the H4R antagonist JNJ7777120 normalized the number of nigrostriatal dopaminergic fibers and striatal dopamine levels in a rotenone-induced PD rat model. These improvements were accompanied by a reduction of α-synuclein-positive inclusions in the striatum. In addition, intracerebroventricular infusion of JNJ7777120 alleviated the morphological changes in Iba-1-positive microglia and resulted in a lower tumor necrosis factor-α release from this brain region, as well as in ameliorated apomorphine-induced rotation behaviour. Finally, JNJ7777120 also restored basal ganglia function by decreasing the levels of γ-aminobutyric acid (GABA) and the 5-hydroxyindoleactic acid to serotonin (5-HIAA/5-HT) concentration ratios in the striatum of the PD model. Our results highlight H4R inhibition in microglia as a promising and specific therapeutic target to reduce or prevent neuroinflammation, and as such the development of PD pathology.

Assessment of the Telomere Length and Its Effect on the Symptomatology of Parkinson's Disease

Telomeres, which are repetitive sequences that cap the end of the chromosomes, shorten with each cell division. Besides cellular aging, there are several other factors that influence telomere length (TL), in particular, oxidative stress and inflammation, which play an important role in the pathogenesis of neurodegenerative brain diseases including Parkinson’s disease (PD). So far, the majority of studies have not demonstrated a significant difference in TL between PD patients and healthy individuals. However, studies investigating the effect of TL on the symptomatology and disease progression of PD are scarce, and thus, warranted. We analyzed TL of peripheral blood cells in a sample of 204 PD patients without concomitant autoimmune diseases and analyzed its association with several PD related phenotypes. Monochrome multiplex quantitative PCR (mmqPCR) was used to determine relative TL given as a ratio of the amount of DNA between the telomere and albumin as the housekeeping gene. We found a significant difference in the relative TL between PD patients with and without dementia, where shorter TL presented higher risk for dementia (p = 0.024). However, the correlation was not significant after adjustment for clinical factors (p = 0.509). We found no correlations between TLs and the dose of dopaminergic therapy when the analysis was adjusted for genetic variability in inflammatory or oxidative factors. In addition, TL influenced time to onset of motor complications after levodopa treatment initiation (p = 0.0134), but the association did not remain significant after adjustment for age at inclusion and disease duration (p = 0.0781). Based on the results of our study we conclude that TL contributes to certain PD-related phenotypes, although it may not have a major role in directing the course of the disease. Nevertheless, this expends currently limited knowledge regarding the association of the telomere attrition and the disease severity or motor complications in Parkinson’s disease.

ATP-sensitive potassium channel subunits in the neuroinflammation: novel drug targets in neurodegenerative disorders

Arachidonic acids and its metabolites modulate plenty of ligand-gated, voltage-dependent ion channels, and metabolically regulated potassium channels including ATP-sensitive potassium channels (KATP). KATP channels are hetero-multimeric complexes of sulfonylureas receptors (SUR1, SUR2A or SUR2B) and the pore-forming subunits (Kir6.1 and Kir6.2) likewise expressed in the pre-post synapsis of neurons and inflammatory cells, thereby affecting their proliferation and activity. KATP channels are involved in amyloid-β (Aβ)-induced pathology, therefore emerging as therapeutic targets against Alzheimer's and related diseases. The modulation of these channels can represent an innovative strategy for the treatment of neurodegenerative disorders; nevertheless, the currently available drugs are not selective for brain KATP channels and show contrasting effects. This phenomenon can be a consequence of the multiple physiological roles of the different varieties of KATP channels. Openings of cardiac and muscular KATP channel subunits, is protective against caspase-dependent atrophy in these tissues and some neurodegenerative disorders, whereas in some neuroinflammatory diseases benefits can be obtained through the inhibition of neuronal KATP channel subunits. For example, glibenclamide exerts an anti-inflammatory effect in respiratory, digestive, urological, and central nervous system (CNS) diseases, as well as in ischemia-reperfusion injury associated with abnormal SUR1-Trpm4/TNF-α or SUR1-Trpm4/ Nos2/ROS signaling. Despite this strategy is promising, glibenclamide may have limited clinical efficacy due to its unselective blocking action of SUR2A/B subunits also expressed in cardiovascular apparatus with pro-arrhythmic effects and SUR1 expressed in pancreatic beta cells with hypoglycemic risk. Alternatively, neuronal selective dual modulators showing agonist/antagonist actions on KATP channels can be an option.

Iron Dysregulation and Inflammagens Related to Oral and Gut Health Are Central to the Development of Parkinson's Disease

Neuronal lesions in Parkinson's disease (PD) are commonly associated with α-synuclein (α-Syn)-induced cell damage that are present both in the central and peripheral nervous systems of patients, with the enteric nervous system also being especially vulnerable. Here, we bring together evidence that the development and presence of PD depends on specific sets of interlinking factors that include neuroinflammation, systemic inflammation, α-Syn-induced cell damage, vascular dysfunction, iron dysregulation, and gut and periodontal dysbiosis. We argue that there is significant evidence that bacterial inflammagens fuel this systemic inflammation, and might be central to the development of PD. We also discuss the processes whereby bacterial inflammagens may be involved in causing nucleation of proteins, including of α-Syn. Lastly, we review evidence that iron chelation, pre-and probiotics, as well as antibiotics and faecal transplant treatment might be valuable treatments in PD. A most important consideration, however, is that these therapeutic options need to be validated and tested in randomized controlled clinical trials. However, targeting underlying mechanisms of PD, including gut dysbiosis and iron toxicity, have potentially opened up possibilities of a wide variety of novel treatments, which may relieve the characteristic motor and nonmotor deficits of PD, and may even slow the progression and/or accompanying gut-related conditions of the disease.

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

Parkinson's disease (PD) is a neurodegenerative disorder, caused by, so far, unknown pathogenetic mechanisms. There is no doubt that pro-inflammatory immune-mediated mechanisms are pivotal to the pathogenicity and progression of the disease. In this review, we highlight the binary role of microglia activation in the pathophysiology of the disorder, both neuroprotective and neuromodulatory. We present how the expression of several cytokines implicated in dopaminergic neurons (DA) degeneration could be used as biomarkers for PD. Viral infections have been studied and correlated to the disease progression, usually operating as trigger factors for the inflammatory process. The gut-brain axis and the possible contribution of the peripheral bowel inflammation to neuronal death, mainly dopaminergic neurons, seems to be a main contributor of brain neuroinflammation. The role of the immune system has also been analyzed implicating a-synuclein in the activation of innate and adaptive immunity. We also discuss therapeutic approaches concerning PD and neuroinflammation, which have been studied in experimental and in vitro models and data stemming from epidemiological studies.

Potential therapeutic and pharmacological effects of Wogonin: an updated review

Flavonoids are members of polyphenolic compounds, which are naturally presented in fruits, vegetables, and some medicinal plants. Traditionally, the root of Scutellaria baicalensis is widely used as Chinese herbal medicine and contains several major bioactive compounds such as Wogonin, Scutellarein, Baicalein, and Baicalin. Experimental and clinical evidence has been proving that Wogonin exhibits diverse biological activities such as anti-cancer, anti-inflammation, and treatment of bacterial and viral infections. In this review, we summarize and emphasize the benefits of Wogonin as a therapeutic adjuvant for anti-viral infection, anti-inflammation, neuroprotection as well as anxiolytic and anticonvulsant. Moreover, the molecular mechanism(s) how Wogonin mediates the cellular signal pathways and immune responses are also discussed and highlighted valuable properties of Wogonin in multiple therapies.

Iron and inflammation: in vivo and post-mortem studies in Parkinson's disease

In these present studies, in vivo and and post-mortem studies have investigated the association between iron and inflammation. Early-stage Parkinson's disease (PD) patients, of less than 5 years disease duration, showed associations of plasmatic ferritin concentrations with both proinflammatory cytokine interleukin-6 and hepcidin, a regulator of iron metabolism as well as clinical measures. In addition ratios of plasmatic ferritin and iron accumulation in deep grey matter nuclei assessed with relaxometry T2* inversely correlated with disease severity and duration of PD. On the hand, post-mortem material of the substantia nigra compacta (SNc) divided according to Braak and Braak scores, III-IV and V-VI staging, exhibited comparable microgliosis, with a variety of phenotypes present. There was an association between the intensity of microgliosis and iron accumulation as assayed by Perl's staining in the SNc sections. In conclusion, markers of inflammation and iron metabolism in both systemic and brain systems are closely linked in PD, thus offering a potential biomarker for progression of the disease.

Genome-Scale Expression Pattern of Long Non-Coding RNAs in Chinese Uyghur Patients with Parkinson's Disease

BACKGROUND Long non-coding RNAs (lncRNAs) are transcripts thought to regulate gene expression at the post-transcriptional level. Some lncRNAs are associated with Parkinson's disease (PD) and participate in pathological processes of PD. The incidence of PD is relatively high in members of the Uyghur minority living in Xingjiang province of China. This study measured the expression of lncRNAs in the peripheral blood cells of Chinese Uyghur individuals with and without PD and analyzed the possible function of these lncRNAs in the development of PD. MATERIAL AND METHODS Peripheral blood samples were collected from 55 Uyghur patients with PD and 55 healthy volunteers. Total RNA was extracted, and the levels of expression of whole-genome lncRNAs and mRNAs in 10 samples (5 PD and 5 controls) were determined by microarray method. The expression levels of lncRNAs in all 100 subjects were determined by qRT-PCR. The lncRNA expression profiles of PD patients were determined based on lncRNA microarray chip analysis, and differentially expressed lncRNAs were identified. The results of chip analysis were confirmed in a large clinical cohort. RESULTS Comparison of subjects with and without PD identified 32 significantly up-regulated and 18 significantly down-regulated lncRNAs in the PD group. GO analysis showed that mRNAs encoding proteins involved in the regulation of biological processes were differentially expressed, with the inflammatory immune response being the most significantly related pathway. CONCLUSIONS The expression of lncRNAs in peripheral blood differed significantly in PD patients and controls. These differentially expressed lncRNAs may play a role in the development of PD.

Nonsteroidal Anti-inflammatory Use and LRRK2 Parkinson's Disease Penetrance

BACKGROUND

The penetrance of leucine rich repeat kinase 2 (LRRK2) mutations is incomplete and may be influenced by environmental and/or other genetic factors. Nonsteroidal anti-inflammatory drugs (NSAIDs) are known to reduce inflammation and may lower Parkinson's disease (PD) risk, but their role in LRRK2-associated PD is unknown.

OBJECTIVES

The objective of this study is to evaluate the association of regular NSAID use and LRRK2-associated PD.

METHODS

Symptomatic ("LRRK2-PD") and asymptomatic ("LRRK2-non-PD") participants with LRRK2 G2019S, R1441X, or I2020T variants (definitely pathogenic variant carriers) or G2385R or R1628P variants (risk variant carriers) from 2 international cohorts provided information on regular ibuprofen and/or aspirin use (≥2 pills/week for ≥6 months) prior to the index date (diagnosis date for PD, interview date for non-PD). Multivariate logistic regression was used to evaluate the relationship between regular NSAID use and PD for any NSAID, separately for ibuprofen and aspirin in all carriers and separately in pathogenic and risk variant groups.

RESULTS

A total of 259 LRRK2-PD and 318 LRRK2-non-PD participants were enrolled. Regular NSAID use was associated with reduced odds of PD in the overall cohort (odds ratio [OR], 0.34; 95% confidence interval [CI], 0.21-0.57) and in both pathogenic and risk variant carriers (ORPathogenic , 0.38; 95% CI, 0.21-0.67 and ORRiskVariant , 0.19; 95% CI, 0.04-0.99). Similar associations were observed for ibuprofen and aspirin separately (ORIbuprofen , 0.19; 95% CI, 0.07-0.50 and ORAspirin , 0.51; 95% CI, 0.28-0.91).

CONCLUSIONS

Regular NSAID use may be associated with reduced penetrance in LRRK2-associated PD. The LRRK2 protein is involved in inflammatory pathways and appears to be modulated by regular anti-inflammatory use. Longitudinal observational and interventional studies of NSAID exposure and LRRK2-PD are needed to confirm this association. © 2020 International Parkinson and Movement Disorder Society.

Faecal Transplantation, Pro- and Prebiotics in Parkinson's Disease; Hope or Hype?

Abstract Faecal microbiome transplantation (FMT) is an attractive technique, because the administration is relatively simple and in general has a mild adverse effect pattern. Moreover, FMT consists of a broad mixture, which could be beneficial, because at this moment it is not known what type of changes in the microbiome are needed. However, except from a few cases no clinical data in Parkinson’s disease (PD) is available yet. There is some indication that FMT might be beneficial in severe constipated PD patients, but the clinical data to support this are very scarce. So, actually there are no good data in the public domain to support FMT at this moment in PD patients. FMT at this moment is a black box with too many unanswered questions, also with respect to safety concerns. Only the administration of species of Lactobacillus and Bifidobacterium over a time period of four to twelve weeks has repeatedly proven to be effective in treating constipation in PD. Also, no solid clinical data are available about the possible effects of probiotic treatment on motor symptoms or progression of PD. Therefore, also probiotic treatments in PD should wait until better clinical data become available, in order to select the right target populations and to have good estimates of the clinical effects to be expected.

Studying the Pathophysiology of Parkinson's Disease Using Zebrafish

Parkinson's disease is a common neurodegenerative disorder leading to severe disability. The clinical features reflect progressive neuronal loss, especially involving the dopaminergic system. The causes of Parkinson's disease are slowly being uncovered and include both genetic and environmental insults. Zebrafish have been a valuable tool in modeling various aspects of human disease. Here, we review studies utilizing zebrafish to investigate both genetic and toxin causes of Parkinson's disease. They have provided important insights into disease mechanisms and will be of great value in the search for disease-modifying therapies.

A novel multi-marker discovery approach identifies new serum biomarkers for Parkinson's disease in older people: an EXosomes in PArkiNson Disease (EXPAND) ancillary study

Dopaminergic nigrostriatal denervation and widespread intracellular α-synuclein accumulation are neuropathologic hallmarks of Parkinson's disease (PD). A constellation of peripheral processes, including metabolic and inflammatory changes, are thought to contribute to neurodegeneration. In the present study, we sought to obtain insight into the multifaceted pathophysiology of PD through the application of a multi-marker discovery approach. Fifty older adults aged 70+, 20 with PD and 30 age-matched controls were enrolled as part of the EXosomes in PArkiNson Disease (EXPAND) study. A panel of 68 circulating mediators of inflammation, neurogenesis and neural plasticity, and amino acid metabolism was assayed. Biomarker selection was accomplished through sequential and orthogonalized covariance selection (SO-CovSel), a multi-platform regression method developed to handle highly correlated variables organized in multi-block datasets. The SO-CovSel model with the best prediction ability using the smallest number of variables was built with seven biomolecules. The model allowed correct classification of 94.2 ± 3.1% participants with PD and 100% controls. The biomarker profile of older adults with PD was defined by higher circulating levels of interleukin (IL) 8, macrophage inflammatory protein (MIP)-1β, phosphoethanolamine, and proline, and by lower concentrations of citrulline, IL9, and MIP-1α. Our innovative approach allowed identifying and evaluating the classification performance of a set of potential biomarkers for PD in older adults. Future studies are warranted to establish whether these biomolecules could serve as biomarkers for PD as well as unveil new targets for interventions.

Single Inflammatory Trigger Leads to Neuroinflammation in LRRK2 Rodent Model without Degeneration of Dopaminergic Neurons

BACKGROUND

Leucine-rich repeat kinase 2 (LRRK2) mutations are the most common genetic risk factor for Parkinson's disease (PD). While the corresponding pathogenic mechanisms remain largely unknown, LRRK2 has been implicated in the immune system.

OBJECTIVE

To assess whether LRRK2 mutations alter the sensitivity to a single peripheral inflammatory trigger, with ultimate impact on dopaminergic integrity, using a longitudinal imaging-based study design.

METHODS

Rats carrying LRRK2 p.G2019S and non-transgenic (NT) littermates were treated peripherally with lipopolysaccharide (LPS). They were monitored over 10 months with PET markers for neuroinflammation and dopaminergic integrity, and with behavioral testing. Tyrosine hydroxylase and CD68 expression were assessed postmortem, 12 months after LPS treatment, in the striatum and substantia nigra.

RESULTS

Longitudinal [11C]PBR28 PET imaging revealed that LPS treatment caused inflammation in the brain, increasing over time, as compared to saline (corrected p = 0.008). LPS treated LRRK2 animals exhibited significantly increased neuroinflammation in the cortex and ventral-regions compared to saline treated animals (LRRK2 and NT) at 10 months post treatment, with the increase in [11C]PBR28 binding from baseline averaging 0.128±0.045 g/mL. For LPS treated NT animals, the increase was not significant. CD68 immunohistochemistry data supported the imaging results, but without reaching statistical significance. No dopaminergic degeneration was observed.

CONCLUSION

A single peripheral inflammatory trigger elicited long lasting, progressive neuroinflammation. A trend for an exacerbated inflammatory response in LRRK2 animals compared to NT controls was observed. Translationally, this implies that repeated exposure to inflammatory triggers may be needed for LRRK2 mutation carriers to develop active PD.

Mitochondrial clearance and maturation of autophagosomes are compromised in LRRK2 G2019S familial Parkinson's disease patient fibroblasts

This study utilized human fibroblasts as a preclinical discovery and diagnostic platform for identification of cell biological signatures specific for the LRRK2 G2019S mutation producing Parkinson's disease (PD). Using live cell imaging with a pH-sensitive Rosella biosensor probe reflecting lysosomal breakdown of mitochondria, mitophagy rates were found to be decreased in fibroblasts carrying the LRRK2 G2019S mutation compared to cells isolated from healthy subject (HS) controls. The mutant LRRK2 increased kinase activity was reduced by pharmacological inhibition and targeted antisense oligonucleotide treatment, which normalized mitophagy rates in the G2019S cells and also increased mitophagy levels in HS cells. Detailed mechanistic analysis showed a reduction of mature autophagosomes in LRRK2 G2019S fibroblasts, which was rescued by LRRK2 specific kinase inhibition. These findings demonstrate an important role for LRRK2 protein in regulation of mitochondrial clearance by the lysosomes, which is hampered in PD with the G2019S mutation. The current results are relevant for cell phenotypic diagnostic approaches and potentially for stratification of PD patients for targeted therapy.

Mitochondrial Signatures in Circulating Extracellular Vesicles of Older Adults with Parkinson's Disease: Results from the EXosomes in PArkiNson's Disease (EXPAND) Study

Systemic inflammation and mitochondrial dysfunction are involved in neurodegeneration in Parkinson’s disease (PD). Extracellular vesicle (EV) trafficking may link inflammation and mitochondrial dysfunction. In the present study, circulating small EVs (sEVs) from 16 older adults with PD and 12 non-PD controls were purified and characterized. A panel of serum inflammatory biomolecules was measured by multiplex immunoassay. Protein levels of three tetraspanins (CD9, CD63, and CD81) and selected mitochondrial markers (adenosine triphosphate 5A (ATP5A), mitochondrial cytochrome C oxidase subunit I (MTCOI), nicotinamide adenine dinucleotide reduced form (NADH):ubiquinone oxidoreductase subunit B8 (NDUFB8), NADH:ubiquinone oxidoreductase subunit S3 (NDUFS3), succinate dehydrogenase complex iron sulfur subunit B (SDHB), and ubiquinol-cytochrome C reductase core protein 2 (UQCRC2)) were quantified in purified sEVs by immunoblotting. Relative to controls, PD participants showed a greater amount of circulating sEVs. Levels of CD9 and CD63 were lower in the sEV fraction of PD participants, whereas those of CD81 were similar between groups. Lower levels of ATP5A, NDUFS3, and SDHB were detected in sEVs from PD participants. No signal was retrieved for UQCRC2, MTCOI, or NDUFB8 in either participant group. To identify a molecular signature in circulating sEVs in relationship to systemic inflammation, a low level-fused (multi-platform) partial least squares discriminant analysis was applied. The model correctly classified 94.2% ± 6.1% PD participants and 66.7% ± 5.4% controls, and identified seven biomolecules as relevant (CD9, NDUFS3, C-reactive protein, fibroblast growth factor 21, interleukin 9, macrophage inflammatory protein 1β, and tumor necrosis factor alpha). In conclusion, a mitochondrial signature was identified in circulating sEVs from older adults with PD, in association with a specific inflammatory profile. In-depth characterization of sEV trafficking may allow identifying new biomarkers for PD and possible targets for personalized interventions.

WITHDRAWN: Genetics of Parkinson's disease

The Publisher regrets that this article is an accidental duplication of an article that has already been published, DOI of original article: https://doi.org/10.1016/j.mcp.2016.11.001. The duplicate article has therefore been withdrawn. The full Elsevier Policy on Article Withdrawal can be found at https://www.elsevier.com/about/our-business/policies/article-withdrawal.

Anti-neuroinflammatory, protective effects of the synthetic microneurotrophin BNN-20 in the advanced dopaminergic neurodegeneration of "weaver" mice

BNN-20 is a synthetic microneurotrophin, long-term (P1-P21) administration of which exerts potent neuroprotective effect on the "weaver" mouse, a genetic model of progressive, nigrostriatal dopaminergic degeneration. The present study complements and expands our previous work, providing evidence that BNN-20 fully protects the dopaminergic neurons even when administration begins at a late stage of dopaminergic degeneration (>40%). Since neuroinflammation plays a critical role in Parkinson's disease, we investigated the possible anti-neuroinflammatory mechanisms underlying the pharmacological action of BNN-20. The latter was shown to be microglia-mediated, at least in part. Indeed, BNN-20 induced a partial, but significant, reversal of microglia hyperactivation, observed in the untreated "weaver" mouse. Furthermore, it induced a shift in microglia polarization towards the neuroprotective M2 phenotype, suggesting a possible beneficial shifting of microglia activity. This observation was further supported by morphometric measurements. Moreover, BDNF levels, which were severely reduced in the "weaver" mouse midbrain, were restored to normal even after short-term BNN-20 administration. Experiments in "weaver"/NGL (dual GFP/luciferase-NF-κВ reporter) mice using bioluminescence after a short BNN-20 treatment (P60-P74), have shown that the increase of BDNF production was specifically mediated through the TrkB-PI3K-Akt-NF-κB signaling pathway. Interestingly, long-term BNN-20 treatment (P14-P60) significantly increased dopamine levels in the "weaver" striatum, which seems to be associated with the improved motor activity observed in the treated mutant animals. In conclusion, our findings suggest that BNN-20 may serve as a lead molecule for new therapeutic compounds for Parkinson's disease, combining strong anti-neuroinflammatory and neuroprotective properties, leading to elevated dopamine levels and improved motor activity.

CXCL12 is involved in α-synuclein-triggered neuroinflammation of Parkinson's disease

BACKGROUND

The mechanisms underlying the pathogenesis and progression of Parkinson's disease (PD) remain elusive, but recent opinions and perspectives have focused on whether the inflammation process induced by microglia contributes to α-synuclein-mediated toxicity. Migration of microglia to the substantia nigra (SN) could precede neurodegeneration in A53T mice. We hypothesized that CXCL12 could be a mediator in the α-synuclein-induced migration of microglia.

METHODS

After establishing appropriate animal and cell culture models, we explored the relationship between α-synuclein and CXCL12 in A53T mice, primary microglia, and BV-2 cell lines. We also explored the mechanisms of these interactions and the signaling processes involved in neuroinflammation.

RESULTS

We confirmed the positive correlation between α-synuclein and CXCL12 in the postmortem brain tissue of PD patients and the upregulated CXCR4 expression in SN microglia of A53T mice. In addition, as expected, α-synuclein increased the production of CXCL12 in microglia via TLR4/IκB-α/NF-κB signaling. Importantly, CXCL12/CXCR4/FAK/Src/Rac1 signaling was shown to be involved in α-synuclein-induced microglial accumulation.

CONCLUSIONS

Our study suggests that CXCL12 could be a novel target for the prevention of α-synuclein-triggered ongoing microglial responses. Blocking CXCL12/CXCR4 may be a potential therapeutic approach for PD progression.

The potential role of necroptosis in inflammaging and aging

An age-associated increase in chronic, low-grade sterile inflammation termed "inflammaging" is a characteristic feature of mammalian aging that shows a strong association with occurrence of various age-associated diseases. However, the mechanism(s) responsible for inflammaging and its causal role in aging and age-related diseases are not well understood. Age-associated accumulation of damage-associated molecular patterns (DAMPs) is an important trigger in inflammation and has been proposed as a potential driver of inflammaging. DAMPs can initiate an inflammatory response by binding to the cell surface receptors on innate immune cells. Programmed necrosis, termed necroptosis, is one of the pathways that can release DAMPs, and cell death due to necroptosis is known to induce inflammation. Necroptosis-mediated inflammation plays an important role in a variety of age-related diseases such as Alzheimer's disease, Parkinson's disease, and atherosclerosis. Recently, it was reported that markers of necroptosis increase with age in mice and that dietary restriction, which retards aging and increases lifespan, reduces necroptosis and inflammation. Genetic manipulations that increase lifespan (Ames Dwarf mice) and reduce lifespan (Sod1-/- mice) are associated with reduced and increased necroptosis and inflammation, respectively. While necroptosis evolved to protect cells/tissues from invading pathogens, e.g., viruses, we propose that the age-related increase in oxidative stress, mTOR signaling, and cell senescence results in cells/tissues in old animals being more prone to undergo necroptosis thereby releasing DAMPs, which contribute to the chronic inflammation observed with age. Approach to decrease DAMPs release by reducing/blocking necroptosis is a potentially new approach to reduce inflammaging, retard aging, and improve healthspan.