Ischemic stroke causes Parkinson's disease-like pathology and symptoms in transgenic mice overexpressing alpha-synuclein

Regulatory mechanism of miR-20a-5p in neuronal damage and inflammation in lipopolysaccharide-induced BV2 cells and MPTP-HCl-induced Parkinson's disease mice

BACKGROUND

Parkinson's disease (PD) is a prevailing neurodegenerative disorder increasingly affecting the elderly population. The involvement of microRNAs (miRNAs) in PD has been confirmed. We sought to explore the molecular mechanism of miR-20a-5p in PD.

METHODS

Lipopolysaccharide (LPS)-induced BV2 cell model and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine hydrochloride (MPTP-HCl)-induced PD mouse model were established. miR-20a-5p, inducible nitric oxide synthase (iNOS), interleukin (IL)-6, tumour necrosis factor (TNF)-α, transforming growth factor (TGF)-β1, and IL-10 expression in BV2 cells was examined by reverse transcription - quantitative polymerase chain reaction. Cell viability was assessed by MTT assay. The apoptotic rate and levels of Bcl-2, Bax, cleaved caspase-3, and signal transducer and activator of transmission (STAT)3 were examined by flow cytometry and Western blot. Bioinformatics software predicted the potential binding sites of miR-20a-5p and STAT3. Dual-luciferase experiment verified the binding relationship. Iba1-positive and tyrosine hydroxylase (TH)-positive cell numbers in substantia nigra pars compacta were detected by immunohistochemistry. The effect of miR-20a-5p on motor function in MPTP-induced PD mice was detected by Rota-rod test, Pole test, Traction test and Beam-crossing task.

RESULTS

miR-20a-5p was under-expressed in LPS-induced BV2 cells. Overexpression of miR-20a-5p increased the viability of LPS-induced BV2 cells and reduced apoptosis rates. Moreover, overexpression of miR-20a-5p reduced cleaved caspase-3, Bax, iNOS, IL-6, and TNF-α and increased Bcl-2 and TGF-β1, and IL-10. miR-20a-5p targeted STAT3. STAT3 overexpression partially reversed miR-20a-5p overexpression-mediated effects on LPS-induced BV2 cell viability, apoptosis, and inflammatory responses. miR-20a-5p overexpression inhibited MPTP-induced STAT3 and α-synuclein levels, microglia activation, and inflammatory response, and reduced the loss of TH-positive cells in mice. miR-20a-5p overexpression ameliorated MPTP-induced dyskinesia in PD model mice.

CONCLUSION

miR-20a-5p alleviates neuronal damage and suppresses inflammation by targeting STAT3 in PD.

Risk of Parkinson disease in stroke patients: A nationwide cohort study in South Korea

BACKGROUND AND PURPOSE

Previous studies have examined the risk of stroke in patients with Parkinson disease (PD), but the incidence of PD onset among stroke patients and its risk according to severity of poststroke disabilities have scarcely been investigated. This study aims to determine whether the risk of PD is increased among stroke patients using a retrospective cohort with a large population-based database.

METHODS

We used data collected by the Korean National Health Insurance Service from 2010 to 2018 and examined 307,361 stroke patients and 380,917 sex- and age-matched individuals without stroke to uncover the incidence of PD. Cox proportional hazards regression was used to calculate the hazard ratio (HR) and 95% confidence interval (CI), and the risk of PD was compared according to presence and severity of disability.

RESULTS

During 4.31 years of follow-up, stroke patients had a 1.67 times higher risk of PD compared to individuals without stroke (adjusted HR = 1.67, 95% CI = 1.57-1.78). The risk of PD was greater among stroke patients with disabilities than among those without disabilities, even after adjustment for multiple covariates (adjusted HR = 1.72, 95% CI = 1.55-1.91; and adjusted HR = 1.66, 95% CI = 1.56-1.77, respectively).

CONCLUSIONS

Our study demonstrated an increased risk of PD among stroke patients. Health professionals need to pay careful attention to detecting movement disorders as clues for diagnosing PD.

Increasing incidence of Parkinson's disease in patients with epilepsy: A Nationwide cohort study

BACKGROUND

Although epilepsy is an uncommon comorbidity of Parkinson's disease (PD), the exact incidence of PD among the patients with epilepsy is not clarified yet.

OBJECTIVES

We aimed to estimate the incidence of PD in patients with epilepsy and explore the association between epilepsy and PD.

METHODS

Epilepsy patients enrolled in the National Health Insurance Service Health Screening Cohort (NHIS-HealS) (2002-2013) between 2003 and 2007 were set up as the experimental group. The major outcome was the occurrence of PD. Non-epilepsy patients were obtained through Propensity Score Matching of 'greedy nearest neighbor' algorithm in 1:1 ratio. The Cox Proportional Hazards model was used to calculate PD incidence and hazard ratio (HR).

RESULTS

A total of 10,510 patients were finally included in the study, which contained 5255 patients in epilepsy and non-epilepsy groups, respectively. During the follow-up period, 85 patients with Parkinson's disease among 5255 patients with epilepsy and 57 patients with Parkinson's disease among 5255 patients without epilepsy occurred. The 10,000 Person-Year (PY), representing the number of PD patients per 10,000 per year, was 21.38 in the epilepsy group and 11.18 in the non-epilepsy group. When all variables were adjusted, it was found that the epilepsy group had a 2.19 times significantly higher risk of developing Parkinson's disease than the control group (The adjusted HR: 2.19 (95% CI, 1.55-3.12)).

CONCLUSION

This study indicates an increased risk of PD in patients with epilepsy. However, further research is needed to prove an exact causal relationship between these two brain disorders.

The contribution of β-amyloid, Tau and α-synuclein to blood-brain barrier damage in neurodegenerative disorders

Central nervous system (CNS) accumulation of fibrillary deposits made of Amyloid β (Aβ), hyperphosphorylated Tau or α-synuclein (α-syn), present either alone or in the form of mixed pathology, characterizes the most common neurodegenerative diseases (NDDs) as well as the aging brain. Compelling evidence supports that acute neurological disorders, such as traumatic brain injury (TBI) and stroke, are also accompanied by increased deposition of toxic Aβ, Tau and α-syn species. While the contribution of these pathological proteins to neurodegeneration has been experimentally ascertained, the cellular and molecular mechanisms driving Aβ, Tau and α-syn-related brain damage remain to be fully clarified. In the last few years, studies have shown that Aβ, Tau and α-syn may contribute to neurodegeneration also by inducing and/or promoting blood-brain barrier (BBB) disruption. These pathological proteins can affect BBB integrity either directly by affecting key BBB components such as pericytes and endothelial cells (ECs) or indirectly, by promoting brain macrophages activation and dysfunction. Here, we summarize and critically discuss key findings showing how Aβ, Tau and α-syn can contribute to BBB damage in most common NDDs, TBI and stroke. We also highlight the need for a deeper characterization of the role of these pathological proteins in the activation and dysfunction of brain macrophages, pericytes and ECs to improve diagnosis and treatment of acute and chronic neurological disorders.

Hypoxia Sensing and Responses in Parkinson's Disease

Parkinson's disease (PD) is associated with various deficits in sensing and responding to reductions in oxygen availability (hypoxia). Here we summarize the evidence pointing to a central role of hypoxia in PD, discuss the relation of hypoxia and oxygen dependence with pathological hallmarks of PD, including mitochondrial dysfunction, dopaminergic vulnerability, and alpha-synuclein-related pathology, and highlight the link with cellular and systemic oxygen sensing. We describe cases suggesting that hypoxia may trigger Parkinsonian symptoms but also emphasize that the endogenous systems that protect from hypoxia can be harnessed to protect from PD. Finally, we provide examples of preclinical and clinical research substantiating this potential.

Molecular mechanism of cognitive impairment associated with Parkinson's disease: A stroke perspective

Parkinson's disease (PD) is a common neurological illness that causes several motor and non-motor symptoms, most characteristically limb tremors and bradykinesia. PD is a slowly worsening disease that arises due to progressive neurodegeneration of specific areas of the brain, especially the substantia nigra of the midbrain. Even though PD has continuously been linked to a higher mortality risk in numerous epidemiologic studies, there have been significant discoveries regarding the connection between PD and stroke. The incidence of strokes such as cerebral infarction and hemorrhage is substantially associated with the development of PD. Moreover, cognitive impairments, primarily dementia, have been associated with stroke and PD. However, the underlying molecular mechanism of this phenomenon is still obscure. This concise review focuses on the relationship between stroke and PD, emphasizing the molecular mechanism of cognition deficit and memory loss evident in PD and stroke. Furthermore, we are also highlighting some potential drug molecules that can target both PD and stroke.

Impaired neuronal activity as a potential factor contributing to the underdeveloped cerebrovasculature in a young Parkinson's disease mouse model

Misfolding of α-synuclein (α-Syn) in the brain causes cellular dysfunction, leading to cell death in a group of neurons, and consequently causes the progression of Parkinson's disease (PD). Although many studies have demonstrated the pathological connections between vascular dysfunction and neurodegenerative diseases, it remains unclear how neuronal accumulation of α-Syn affects the structural and functional aspects of the cerebrovasculature to accelerate early disease progression. Here, we demonstrated the effect of aberrant α-Syn expression on the brain vasculature using a PD mouse model expressing a familial mutant form of human α-Syn selectively in neuronal cells. We showed that young PD mice have an underdeveloped cerebrovasculature without significant α-Syn accumulation in the vasculature. During the early phase of PD, toxic α-Syn was selectively increased in neuronal cells, while endothelial cell proliferation was decreased in the absence of vascular cell death or neuroinflammation. Instead, we observed altered neuronal activation and minor changes in the activity-dependent gene expression in brain endothelial cells (ECs) in young PD mice. These findings demonstrated that neuronal expression of mutant α-Syn in the early stage of PD induces abnormal neuronal activity and contributes to vascular patterning defects, which could be associated with a reduced angiogenic potential of ECs.

The Interplay between Mitochondrial Dysfunction and Ferroptosis during Ischemia-Associated Central Nervous System Diseases

Cerebral ischemia, a leading cause of disability and mortality worldwide, triggers a cascade of molecular and cellular pathologies linked to several central nervous system (CNS) disorders. These disorders primarily encompass ischemic stroke, Alzheimer's disease (AD), Parkinson's disease (PD), epilepsy, and other CNS conditions. Despite substantial progress in understanding and treating the underlying pathological processes in various neurological diseases, there is still a notable absence of effective therapeutic approaches aimed specifically at mitigating the damage caused by these illnesses. Remarkably, ischemia causes severe damage to cells in ischemia-associated CNS diseases. Cerebral ischemia initiates oxygen and glucose deprivation, which subsequently promotes mitochondrial dysfunction, including mitochondrial permeability transition pore (MPTP) opening, mitophagy dysfunction, and excessive mitochondrial fission, triggering various forms of cell death such as autophagy, apoptosis, as well as ferroptosis. Ferroptosis, a novel type of regulated cell death (RCD), is characterized by iron-dependent accumulation of lethal reactive oxygen species (ROS) and lipid peroxidation. Mitochondrial dysfunction and ferroptosis both play critical roles in the pathogenic progression of ischemia-associated CNS diseases. In recent years, growing evidence has indicated that mitochondrial dysfunction interplays with ferroptosis to aggravate cerebral ischemia injury. However, the potential connections between mitochondrial dysfunction and ferroptosis in cerebral ischemia have not yet been clarified. Thus, we analyzed the underlying mechanism between mitochondrial dysfunction and ferroptosis in ischemia-associated CNS diseases. We also discovered that GSH depletion and GPX4 inactivation cause lipoxygenase activation and calcium influx following cerebral ischemia injury, resulting in MPTP opening and mitochondrial dysfunction. Additionally, dysfunction in mitochondrial electron transport and an imbalanced fusion-to-fission ratio can lead to the accumulation of ROS and iron overload, which further contribute to the occurrence of ferroptosis. This creates a vicious cycle that continuously worsens cerebral ischemia injury. In this study, our focus is on exploring the interplay between mitochondrial dysfunction and ferroptosis, which may offer new insights into potential therapeutic approaches for the treatment of ischemia-associated CNS diseases.

Long-term behavioural alterations in mice following transient cerebral ischemia

Ischemic stroke is one of the leading causes of disability and mortality worldwide. Acute and chronic post-stroke changes have variable effects on the functional outcomes of the disease. Therefore, it is imperative to identify what daily activities are altered after stroke and to what extent, keeping in mind that ischemic stroke patients often have long-term post-stroke complications. Translational studies in stroke have also been challenging due to inconsistent study design of animal experiments. The objective of this study was to clarify whether and to what extent mouse behaviour was altered during a 6 months period after cerebral stroke. Experimental stroke was induced in mice by intraluminal filament insertion into the middle cerebral artery (fMCAo). Neurological deficits, recovery rate, motor performance, and circadian activity were evaluated following ischemia. We observed severe neurological deficits, motor impairments, and delay in the recovery rate of mice during the first 14 days after fMCAo. Aberrant circadian activity and distorted space map were seen in fMCAo mice starting one month after ischemia, similarly to altered new and familiar cage activity and sucrose preference using the IntelliCage, and was still evident 60- and 180- days following stroke in the voluntary running wheel using the PhenoMaster system. A preference towards ipsilateral side turns was observed in fMCAo mice both acutely and chronically after the stroke induction. Overall, our study shows the importance of determining time-dependent differences in the long-term post-stroke recovery (over 180 days after fMCAo) using multiple behavioural assessments.

An update on the role of Hippo signaling pathway in ischemia-associated central nervous system diseases

The most frequent reason of morbidity and mortality in the world, cerebral ischemia sets off a chain of molecular and cellular pathologies that associated with some central nervous system (CNS) disorders mainly including ischemic stroke, Alzheimer's disease (AD), Parkinson's disease (PD), epilepsy and other CNS diseases. In recent times, despite significant advancements in the treatment of the pathological processes underlying various neurological illnesses, effective therapeutic approaches that are specifically targeted to minimizing the damage of such diseases remain absent. Hippo signaling pathway, characterized by enzyme linked reactions between MSTI/2, LAST1/2, and YAP or TAZ proteins, controls cell division, survival, and differentiation, as well as being engaged in a variety of biological activities, such as the development and transformation of the nervous system. Recently, accumulating studies demonstrated that Hippo pathway takes part in the processes of ischemic stroke, AD, PD, etc., including but not limited to oxidative stress, inflammatory response, blood-brain barrier damage, mitochondrial disorders, and neural cells death. Thus, it's crucial to understand the molecular basis of the Hippo signaling pathway for determining potential new therapeutic targets against ischemia-associated CNS diseases. Here, we discuss latest advances in the deciphering of the Hippo signaling pathway and highlight the therapeutic potential of targeting the pathway in treating ischemia-associated CNS diseases.

CDR1as regulates α-synuclein-mediated ischemic brain damage by controlling miR-7 availability

Transient focal ischemia decreased microRNA-7 (miR-7) levels, leading to derepression of its major target α-synuclein (α-Syn) that promotes secondary brain damage. Circular RNA CDR1as is known to regulate miR-7 abundance and function. Hence, we currently evaluated its functional significance after focal ischemia. Transient middle cerebral artery occlusion (MCAO) in adult mice significantly downregulated both CDR1as and miR-7 levels in the peri-infarct cortex between 3 and 72 h of reperfusion. Interestingly, neither pri-miR-7a nor 7b was altered in the ischemic brain. Intracerebral injection of an AAV9 vector containing a CDR1as gene significantly increased CDR1as levels by 21 days that persisted up to 4 months without inducing any observable toxicity in both sham and MCAO groups. Following transient MCAO, there was a significant increase in miR-7 levels and CDR1as binding to Ago2/miR-7 in the peri-infarct cortex of AAV9-CDR1as cohort compared with AAV9-Control cohort at 1 day of reperfusion. CDR1as overexpression significantly suppressed post-stroke α-Syn protein induction, promoted motor function recovery, decreased infarct size, and curtailed the markers of apoptosis, autophagy mitochondrial fragmentation, and inflammation in the post-stroke brain compared with AAV9-Control-treated cohort. Overall, our findings imply that CDR1as reconstitution is neuroprotective after stroke, probably by protecting miR-7 and preventing α-Syn-mediated neuronal death.

Long Short-Term Memory-Based Deep Learning Models for Screening Parkinson's Disease Using Sequential Diagnostic Codes

BACKGROUND AND PURPOSE

It is challenging to detect Parkinson's disease (PD) in its early stages, which has prompted researchers to develop techniques based on machine learning methods for detecting PD. However, previous studies did not fully incorporate the slow progression of PD over a long period of time nor consider that its symptoms occur in a time-sequential manner. Contributing to the literature on PD, which has relied heavily on cross-sectional data, this study aimed to develop a method for detecting PD early that can process time-series information using the long short-term memory (LSTM) algorithm.

METHODS

We sampled 926 patients with PD and 9,260 subjects without PD using medical-claims data. The LSTM algorithm was tested using diagnostic histories, which contained the diagnostic codes and their respective time information. We compared the prediction power of the 12-month diagnostic codes under two different settings over the 4 years prior to the first PD diagnosis.

RESULTS

The model that was trained using the most-recent 12-month diagnostic codes had the best performance, with an accuracy of 94.25%, a sensitivity of 82.91%, and a specificity of 95.26%. The other three models (12-month codes from 2, 3, and 4 years prior) were found to have comparable performances, with accuracies of 92.27%, 91.86%, and 91.81%, respectively. The areas under the curve from our data settings ranged from 0.839 to 0.923.

CONCLUSIONS

We explored the possibility that PD specialists could benefit from our proposed machine learning method as an early detection method for PD.

Abnormal circadian blood pressure regulation and cognitive impairment in α-synucleinopathies

Circadian blood pressure (BP) rhythm is important for the maintenance of healthy daily life, and its disruption is associated with poor outcomes. Cardiovascular autonomic failure is often observed in older populations but has a greater impact on neurodegenerative disorders such as α-synucleinopathies. These BP abnormalities include orthostatic hypotension (OH), supine hypertension (SH), and a loss of nocturnal BP fall. OH not only causes falls or syncope but is also related to cognitive impairment in α-synucleinopathies. For example, OH doubles or triples the risk for the development of cognitive impairment in Parkinson's disease (PD). The diffuse central and peripheral neuropathology of α-synuclein may contribute to both OH and cognitive impairment. Moreover, repeated cerebral hypoperfusion in OH is thought to be related to cerebrovascular and neuronal damage, which may cause cognitive impairment. SH, which often coexists with OH, is also associated with cognitive impairment through cerebrovascular damage, such as white matter lesions and cerebral microbleeds. The reverse-dipping (riser) pattern on ambulatory BP monitoring is commonly observed in PD (∼56%), regardless of disease duration and severity. It is also related to cognitive impairment and more pronounced when coexisting with OH. These abnormal circadian BP profiles may be synergistically associated with cognitive impairment and poor outcomes in α-synucleinopathies. Although evidence for aggressive control of BP dysregulation improving cognitive impairment and outcomes is limited, regular BP monitoring appears to be important for total management of α-synucleinopathies.

Hypoxia and Alpha-Synuclein: Inextricable Link Underlying the Pathologic Progression of Parkinson's Disease

Parkinson's disease (PD) is the second most common neurodegenerative disease after Alzheimer's disease, with typical motor symptoms as the main clinical manifestations. At present, there are about 10 million patients with PD in the world, and its comorbidities and complications are numerous and incurable. Therefore, it is particularly important to explore the pathogenesis of PD and find possible therapeutic targets. Because the etiology of PD is complex, involving genes, environment, and aging, finding common factors is the key to identifying intervention targets. Hypoxia is ubiquitous in the natural environment and disease states, and it is considered to be closely related to the etiology of PD. Despite research showing that hypoxia increases the expression and aggregation of alpha-synuclein (α-syn), the most important pathogenic protein, there is still a lack of systematic studies on the role of hypoxia in α-syn pathology and PD pathogenesis. Considering that hypoxia is inextricably linked with various causes of PD, hypoxia may be a co-participant in many aspects of the PD pathologic process. In this review, we describe the risk factors for PD, and we discuss the possible role of hypoxia in inducing PD pathology by these risk factors. Furthermore, we attribute the pathological changes caused by PD etiology to oxygen uptake disorder and oxygen utilization disorder, thus emphasizing the possibility of hypoxia as a critical link in initiating or promoting α-syn pathology and PD pathogenesis. Our study provides novel insight for exploring the pathogenesis and therapeutic targets of PD.