A case of probable Parkinson's disease after SARS-CoV-2 infection

Infections in the Etiology of Parkinson's Disease and Synucleinopathies: A Renewed Perspective, Mechanistic Insights, and Therapeutic Implications

Increasing evidence suggests a potential role for infectious pathogens in the etiology of synucleinopathies, a group of age-related neurodegenerative disorders including Parkinson's disease (PD), multiple system atrophy and dementia with Lewy bodies. In this review, we discuss the link between infections and synucleinopathies from a historical perspective, present emerging evidence that supports this link, and address current research challenges with a focus on neuroinflammation. Infectious pathogens can elicit a neuroinflammatory response and modulate genetic risk in PD and related synucleinopathies. The mechanisms of how infections might be linked with synucleinopathies as well as the overlap between the immune cellular pathways affected by virulent pathogens and disease-related genetic risk factors are discussed. Here, an important role for α-synuclein in the immune response against infections is emerging. Critical methodological and knowledge gaps are addressed, and we provide new future perspectives on how to address these gaps. Understanding how infections and neuroinflammation influence synucleinopathies will be essential for the development of early diagnostic tools and novel therapies.

Neurological complications caused by SARS-CoV-2

SUMMARYSARS-CoV-2 can not only cause respiratory symptoms but also lead to neurological complications. Research has shown that more than 30% of SARS-CoV-2 patients present neurologic symptoms during COVID-19 (A. Pezzini and A. Padovani, Nat Rev Neurol 16:636-644, 2020, https://doi.org/10.1038/s41582-020-0398-3). Increasing evidence suggests that SARS-CoV-2 can invade both the central nervous system (CNS) (M.S. Xydakis, M.W. Albers, E.H. Holbrook, et al. Lancet Neurol 20: 753-761, 2021 https://doi.org/10.1016/S1474-4422(21)00182-4 ) and the peripheral nervous system (PNS) (M.N. Soares, M. Eggelbusch, E. Naddaf, et al. J Cachexia Sarcopenia Muscle 13:11-22, 2022, https://doi.org/10.1002/jcsm.12896), resulting in a variety of neurological disorders. This review summarized the CNS complications caused by SARS-CoV-2 infection, including encephalopathy, neurodegenerative diseases, and delirium. Additionally, some PNS disorders such as skeletal muscle damage and inflammation, anosmia, smell or taste impairment, myasthenia gravis, Guillain-Barré syndrome, ICU-acquired weakness, and post-acute sequelae of COVID-19 were described. Furthermore, the mechanisms underlying SARS-CoV-2-induced neurological disorders were also discussed, including entering the brain through retrograde neuronal or hematogenous routes, disrupting the normal function of the CNS through cytokine storms, inducing cerebral ischemia or hypoxia, thus leading to neurological complications. Moreover, an overview of long-COVID-19 symptoms is provided, along with some recommendations for care and therapeutic approaches of COVID-19 patients experiencing neurological complications.

COVID-19 and Parkinson's disease: a single-center study and Mendelian randomization study

To investigate the association between COVID-19 and Parkinson's disease (PD) via a single-center study and a Mendelian randomization (MR) study. A questionnaire-based survey was conducted among PD patients at a single center from December 7, 2022, to March 10, 2023. Logistic regression analysis was performed to identify the infection-related risk factors. Subsequently, bidirectional two-sample Mendelian randomization was employed to explore the association between COVID-19 and PD. In the cross-sectional analysis, it was found that the prevalence of COVID-19 infection in PD patients was 65.7%. Forty-eight (35.3%) PD patients experienced exacerbation of motor symptoms following COVID-19 infection. Long PD disease duration (≥ 10 years) (OR: 3.327, P = 0.045) and long time since last vaccination (> 12 m) (OR: 4.916, P = 0.035) were identified as significant risk factors related to infection. The MR analysis results supported that PD increases the COVID-19 susceptibility (β = 0.081, OR = 1.084, P = 0.006). However, the MR analysis showed that PD did not increases the COVID-19 severity and hospitalization, and no significant association of COVID-19 on PD was observed. The findings from this cross-sectional study suggest that individuals with PD may experience worsened motor symptoms following COVID-19 infection. Long disease duration (≥10 years) and long time since last vaccination (> 12 m) are identified as important risk factors for infection in these patients. Furthermore, our MR study provides evidence supporting an association between PD and COVID-19 susceptibility.

No genetic link between Parkinson's disease and SARS-CoV-2 infection: a two-sample Mendelian randomization study

Objective

Existing literature has not clearly elucidated whether SARS-CoV-2 infection increases the incidence of Parkinson's disease or if Parkinson's disease patients are more susceptible to the effects of SARS-CoV-2 infection. To clarify the issue, this study employs a genetic epidemiological approach to investigate the association.

Methods

This study utilizes a two-sample Mendelian randomization analysis. The primary analysis employs the inverse variance-weighted (IVW) method, supplemented by secondary analyses including MR-Egger regression, weighted median, IVW radial method, and weighted mode, to evaluate the bidirectional causal relationship between Parkinson's disease and SARS-CoV-2 infection.

Results

IVW results showed no genetic causality between SARS-CoV-2 susceptibility, hospitalization rate and severity and Parkinson's disease. (IVW method: p = 0.408 OR = 1.10 95% CI: 0.87 ~ 1.39; p = 0.744 OR = 1.11 95% CI: 0.94 ~ 1.09; p = 0.436 OR = 1.05 95% CI: 0.93 ~ 1.17). Parkinson's disease was not genetically associated with susceptibility to new crown infections, hospitalization rates, and severity (IVW method: p = 0.173 OR = 1.01 95% CI: 0.99 ~ 1.03; p = 0.109 OR = 1.05 95% CI: 0.99 ~ 1.12; p = 0.209 OR = 1.03 95% CI: 0.99 ~ 1.07). MR-Egger regression, weighted median, IVW radial method, and weighted mode results are consistent with the results of the IVW method.

Conclusion

This study does not support a genetic link between Parkinson's disease and SARS-CoV-2 infection, and the association observed in previous cohort studies and observational studies may be due to other confounding factors.

Potential convergence of olfactory dysfunction in Parkinson's disease and COVID-19: The role of neuroinflammation

Parkinson's disease (PD) is a prevalent neurodegenerative disorder that affects 7-10 million individuals worldwide. A common early symptom of PD is olfactory dysfunction (OD), and more than 90% of PD patients suffer from OD. Recent studies have highlighted a high incidence of OD in patients with SARS-CoV-2 infection. This review investigates the potential convergence of OD in PD and COVID-19, particularly focusing on the mechanisms by which neuroinflammation contributes to OD and neurological events. Starting from our fundamental understanding of the olfactory bulb, we summarize the clinical features of OD and pathological features of the olfactory bulb from clinical cases and autopsy reports in PD patients. We then examine SARS-CoV-2-induced olfactory bulb neuropathology and OD and emphasize the SARS-CoV-2-induced neuroinflammatory cascades potentially leading to PD manifestations. By activating microglia and astrocytes, as well as facilitating the aggregation of α-synuclein, SARS-CoV-2 could contribute to the onset or exacerbation of PD. We also discuss the possible contributions of NF-κB, the NLRP3 inflammasome, and the JAK/STAT, p38 MAPK, TLR4, IL-6/JAK2/STAT3 and cGAS-STING signaling pathways. Although olfactory dysfunction in patients with COVID-19 may be reversible, it is challenging to restore OD in patients with PD. With the emergence of new SARS-CoV-2 variants and the recurrence of infections, we call for continued attention to the intersection between PD and SARS-CoV-2 infection, especially from the perspective of OD.

Long COVID: From olfactory dysfunctions to viral Parkinsonism

Neurological and psychiatric complications continue to be a public health concern in long coronavirus disease 2019 (COVID-19). This varies from olfactory dysfunctions such as parosmia to cognitive and emotional challenges. Historically, the surge of neurological disorders followed the viral pandemics, for example, the emergence of Encephalitis Lethargica after the outbreak of Spanish Influenza. During and after COVID-19 infection, the problems associated with the sense of smell and the reports of affected olfactory and limbic brain areas are leading to a growing concern about the similarity with the symptoms and the pattern of degeneration observed at the onset of Parkinson's disease and Alzheimer's disease. These reports reveal the essentiality of long-term studies of olfactory and cognitive functions in the post-COVID era and the experiments using animal models to dissect the neural basis of these complications. In this manuscript, we summarize the research reporting the potential correlation between neurological disorders and viral pandemic outbreaks with a historical perspective. Further, we discuss the studies providing evidence of neurodegeneration due to severe acute respiratory syndrome coronavirus 2 infection by focusing on viral Parkinsonism.

Post-COVID parkinsonism: A scoping review

BACKGROUND

The clinical features and outcomes of post-COVID parkinsonism have not been organized systematically, and the possible correlations between COVID-19 and parkinsonism have not been elucidated. This scoping review addresses these two unmet needs.

METHODS

We searched two databases (Pubmed, Embase) for all published cases of post-COVID parkinsonism. Data were extracted from eligible studies using standardized forms and predefined inclusion and exclusion criteria. The patients' clinical features, their diagnosis and outcomes were assessed objectively.

RESULTS

Twenty-six cases of post-COVID parkinsonism were reported in 17 publications. Their presenting features were grouped into three clinical syndromes: typical parkinsonian motor syndrome (12 patients), parkinsonism with postural instability and gait disorder (three), or encephalopathy with parkinsonism (10). Patients had the following diagnoses: clinically established Parkinson's disease (PD, three cases), clinically probable PD (eight), clinically probable multiple system atrophy (one), acquired parkinsonism (six), unclassified parkinsonism (eight). Isolated parkinsonian motor syndromes typically followed uncomplicated COVID-19 illness or pneumonia; instead, encephalopathy with parkinsonism was observed following a wide spectrum of COVID-19-related presentations, including severe forms. PD cases mainly occurred following uncomplicated COVID-19, whereas acquired or unclassified parkinsonism were reported following different COVID-19 presentations.

CONCLUSIONS

Patients with uncomplicated COVID-19 are more likely to present PD and no signs of encephalopathy. There is no demonstration of a causative role of COVID-19, which can be coincidental in several cases. Patients with encephalopathy and parkinsonism constitute a distinct subset, suggesting a potentially different pathogenic role of SARS-CoV-2 infection. These findings provide a basis for further studies in the post-pandemic phase.

SARS-CoV-2 infection exacerbates the cellular pathology of Parkinson's disease in human dopaminergic neurons and a mouse model

While an association between Parkinson's disease (PD) and viral infections has been recognized, the impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) on PD progression remains unclear. Here, we demonstrate that SARS-CoV-2 infection heightens the risk of PD using human embryonic stem cell (hESC)-derived dopaminergic (DA) neurons and a human angiotensin-converting enzyme 2 (hACE2) transgenic (Tg) mouse model. Our findings reveal that SARS-CoV-2 infection exacerbates PD susceptibility and cellular toxicity in DA neurons pre-treated with human preformed fibrils (hPFFs). Additionally, nasally delivered SARS-CoV-2 infects DA neurons in hACE2 Tg mice, aggravating the damage initiated by hPFFs. Mice infected with SARS-CoV-2 display persisting neuroinflammation even after the virus is no longer detectable in the brain. A comprehensive analysis suggests that the inflammatory response mediated by astrocytes and microglia could contribute to increased PD susceptibility associated with SARS-CoV-2. These findings advance our understanding of the potential long-term effects of SARS-CoV-2 infection on the progression of PD.

Neuropathological assessment of the olfactory bulb and tract in individuals with COVID-19

The majority of patients with Parkinson disease (PD) experience a loss in their sense of smell and accumulate insoluble α-synuclein aggregates in their olfactory bulbs (OB). Subjects affected by a SARS-CoV-2-linked illness (COVID-19) also frequently experience hyposmia. We previously postulated that microglial activation as well as α-synuclein and tau misprocessing can occur during host responses following microbial encounters. Using semiquantitative measurements of immunohistochemical signals, we examined OB and olfactory tract specimens collected serially at autopsies between 2020 and 2023. Deceased subjects comprised 50 adults, which included COVID19 + patients (n = 22), individuals with Lewy body disease (e.g., PD; dementia with Lewy bodies (n = 6)), Alzheimer disease (AD; n = 3), and other neurodegenerative disorders (e.g., progressive supranuclear palsy (n = 2); multisystem atrophy (n = 1)). Further, we included neurologically healthy controls (n = 9), and added subjects with an inflammation-rich brain disorder as neurological controls (NCO; n = 7). When probing for microglial and histiocytic reactivity in the anterior olfactory nuclei (AON) by anti-CD68 immunostaining, scores were consistently elevated in NCO and AD cases. In contrast, microglial signals on average were not significantly altered in COVID19 + patients relative to healthy controls, although anti-CD68 reactivity in their OB and tracts declined with progression in age. Mild-to-moderate increases in phospho-α-synuclein and phospho-tau signals were detected in the AON of tauopathy- and synucleinopathy-afflicted brains, respectively, consistent with mixed pathology, as described by others. Lastly, when both sides were available for comparison in our case series, we saw no asymmetry in the degree of pathology of the left versus right OB and tracts. We concluded from our autopsy series that after a fatal course of COVID-19, microscopic changes in the rostral, intracranial portion of the olfactory circuitry -when present- reflected neurodegenerative processes seen elsewhere in the brain. In general, microglial reactivity correlated best with the degree of Alzheimer's-linked tauopathy and declined with progression of age in COVID19 + patients.

Long COVID and its association with neurodegenerative diseases: pathogenesis, neuroimaging, and treatment

Corona Virus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has presented unprecedented challenges to the world. Changes after acute COVID-19 have had a significant impact on patients with neurodegenerative diseases. This study aims to explore the mechanism of neurodegenerative diseases by examining the main pathways of central nervous system infection of SARS-CoV-2. Research has indicated that chronic inflammation and abnormal immune response are the primary factors leading to neuronal damage and long-term consequences of COVID-19. In some COVID-19 patients, the concurrent inflammatory response leads to increased release of pro-inflammatory cytokines, which may significantly impact the prognosis. Molecular imaging can accurately assess the severity of neurodegenerative diseases in patients with COVID-19 after the acute phase. Furthermore, the use of FDG-PET is advocated to quantify the relationship between neuroinflammation and psychiatric and cognitive symptoms in patients who have recovered from COVID-19. Future development should focus on aggressive post-infection control of inflammation and the development of targeted therapies that target ACE2 receptors, ERK1/2, and Ca2+.

The Influence of Microglia on Neuroplasticity and Long-Term Cognitive Sequelae in Long COVID: Impacts on Brain Development and Beyond

Microglial cells, the immune cells of the central nervous system, are key elements regulating brain development and brain health. These cells are fully responsive to stressors, microenvironmental alterations and are actively involved in the construction of neural circuits in children and the ability to undergo full experience-dependent plasticity in adults. Since neuroinflammation is a known key element in the pathogenesis of COVID-19, one might expect the dysregulation of microglial function to severely impact both functional and structural plasticity, leading to the cognitive sequelae that appear in the pathogenesis of Long COVID. Therefore, understanding this complex scenario is mandatory for establishing the possible molecular mechanisms related to these symptoms. In the present review, we will discuss Long COVID and its association with reduced levels of BDNF, altered crosstalk between circulating immune cells and microglia, increased levels of inflammasomes, cytokines and chemokines, as well as the alterations in signaling pathways that impact neural synaptic remodeling and plasticity, such as fractalkines, the complement system, the expression of SIRPα and CD47 molecules and altered matrix remodeling. Together, these complex mechanisms may help us understand consequences of Long COVID for brain development and its association with altered brain plasticity, impacting learning disabilities, neurodevelopmental disorders, as well as cognitive decline in adults.

The effect of SARS-CoV-2 on the development of Parkinson's disease: the role of α-synuclein

The current coronavirus disease 2019 (COVID-19) can lead to various neurological complications in infected people. These neurological effects include problems in both central nervous system (CNS) and peripheral nervous system (PNS). Hyposmia, a PNS symptom of COVID-19, frequently manifests in the early stages of Parkinson's disease (PD) and serves as an early warning sign of the condition. In addition, the olfactory system is recognized as an early site for the onset of α-synuclein pathology, the pathological hallmark of PD. PD is characterized by accumulation and aggregation of misfolded α-synuclein (α-Syn) into Lewy bodies and Lewy neurites, resulting in the degeneration of dopaminergic neurons in substantia nigra pars compacta (SNpc). Previous research has also shown the involvement of α-Syn in the innate immune response following viral infections. Consequently, the potential link between viral infections and development of PD has gained attention in recent years. However, it's still too early to definitively conclude whether COVID-19 can cause Parkinsonism. Nevertheless, we can explore the likelihood of this connection by examining past studies and possible mechanisms to better understand how COVID-19 might potentially lead to PD following the infection. Based on the various pieces of evidence discussed in this review, we can infer that SARS-CoV-2 promotes the aggregation of α-Syn and, ultimately, leads to PD through at least two mechanisms: the stable binding of the S1 protein to proteins prone to aggregation like α-Syn, and the upregulation of α-Syn as part of the immune response to the infection.

The impact of COVID-19 on pulmonary, neurological, and cardiac outcomes: evidence from a Mendelian randomization study

Background

Long COVID is a clinical entity characterized by persistent health problems or development of new diseases, without an alternative diagnosis, following SARS-CoV-2 infection that affects a significant proportion of individuals globally. It can manifest with a wide range of symptoms due to dysfunction of multiple organ systems including but not limited to cardiovascular, hematologic, neurological, gastrointestinal, and renal organs, revealed by observational studies. However, a causal association between the genetic predisposition to COVID-19 and many post-infective abnormalities in long COVID remain unclear.

Methods

Here we employed Mendelian randomization (MR), a robust genetic epidemiological approach, to investigate the potential causal associations between genetic predisposition to COVID-19 and long COVID symptoms, namely pulmonary (pneumonia and airway infections including bronchitis, emphysema, asthma, and rhinitis), neurological (headache, depression, and Parkinson's disease), cardiac (heart failure and chest pain) diseases, and chronic fatigue. Using two-sample MR, we leveraged genetic data from a large COVID-19 genome-wide association study and various disorder-specific datasets.

Results

This analysis revealed that a genetic predisposition to COVID-19 was significantly causally linked to an increased risk of developing pneumonia, airway infections, headache, and heart failure. It also showed a strong positive correlation with chronic fatigue, a frequently observed symptom in long COVID patients. However, our findings on Parkinson's disease, depression, and chest pain were inconclusive.

Conclusion

Overall, these findings provide valuable insights into the genetic underpinnings of long COVID and its diverse range of symptoms. Understanding these causal associations may aid in better management and treatment of long COVID patients, thereby alleviating the substantial burden it poses on global health and socioeconomic systems.

Nucleocapsid proteins from human coronaviruses possess phase separation capabilities and promote FUS pathological aggregation

The nucleocapsid (N) protein is an essential structural component necessary for genomic packaging and replication in various human coronaviruses (HCoVs), such as SARS-CoV-2 and MERS-CoV. Recent studies have revealed that the SARS-CoV-2 N protein exhibits a high capacity for liquid-liquid phase separation (LLPS), which plays multiple roles in viral infection and replication. In this study, we systematically investigate the LLPS capabilities of seven homologous N proteins from different HCoVs using a high-throughput protein phase separation assay. We found that LLPS is a shared intrinsic property among these N proteins. However, the phase separation profiles of the various N protein homologs differ, and they undergo phase separation under distinct in vitro conditions. Moreover, we demonstrate that N protein homologs can co-phase separate with FUS, a SG-containing protein, and accelerate its liquid-to-solid phase transition and amyloid aggregation, which is closely related to amyotrophic lateral sclerosis. Further study shows that N protein homologs can directly bind to the low complexity domain of FUS. Together, our work demonstrates that N proteins of different HCoVs possess phase separation capabilities, which may contribute to promoting pathological aggregation of host proteins and disrupting SG homeostasis during the infection and replication of various HCoVs.

SARS-CoV-2 N-protein induces the formation of composite α-synuclein/N-protein fibrils that transform into a strain of α-synuclein fibrils

The presence of deposits of alpha-synuclein (αS) fibrils in the cells of the brain is a hallmark of several α-synucleinopathies, including Parkinson's disease. As most disease cases are not familial, it is likely that external factors play a role in the disease onset. One of the external factors that may influence the disease onset is viral infection. It has recently been shown in in vitro assays that in the presence of SARS-Cov-2 N-protein, αS fibril formation is faster and proceeds in an unusual two-step aggregation process. Here, we show that faster fibril formation is not due to the SARS-CoV-2 N-protein-catalysed formation of an aggregation-prone nucleus. Instead, aggregation starts with the formation of a population of mixed αS/N-protein fibrils with low affinity for αS. Mixed amyloid fibrils, composed of two different proteins, have not been observed before. After the depletion of N-protein, fibril formation comes to a halt, until a slow transformation into fibrils with characteristics of a pure αS fibril strain occurs. This transformation into a strain of αS fibrils subsequently results in a second phase of fibril growth until a new equilibrium is reached. We hypothesize that this fibril strain transformation may be of relevance in the cell-to-cell spread of the αS pathology and disease onset.

Hydrogen sulfide: From a toxic gas to a potential therapy for COVID-19 and inflammatory disorders

COVID-19 has been shown to induce inflammatory disorders and CNS manifestations. Swift and efficient treatment strategies are urgently warranted for the management of COVID, inflammatory and neurological disorders. Hydrogen sulfide (H2S) has been associated with several clinical disorders due to its potential to influence a broad range of biological signalling pathways. According to recent clinical studies, COVID patients with lower physiological H2S had higher fatality rates. These findings clearly demonstrate an inverse correlation between H2S levels and the severity of COVID-19. H2S has been proposed as a protective molecule because of its antioxidant, anti-inflammatory, and antiviral properties. Various H2S-releasing prodrugs, hybrids and natural compounds have been tested for their therapeutic efficacy in viral infections and inflammatory disorders. In this review, I am highlighting the rationale for using H2S-based interventions for the management of COVID-19 and post-infection inflammatory disorders including neuroinflammation. I am also proposing therepurposing of existing H2S-releasing prodrugs, developing new NO-H2S-hybrids, targeting H2S metabolic pathways, and using H2S-producing dietary supplements as viable defensive strategies against SARS-CoV-2 infection and COVID-19 pathologies.

Rapid progression of probable Creutzfeldt-Jakob disease with concomitant COVID-19 infection

A previously healthy man in his 80s was admitted to a district general hospital with rapidly progressing dementia, gait abnormalities and myoclonus alongside COVID-19 infection. Investigations showed mild elevation of C-reactive protein and neutrophils, unremarkable CT head and mildly raised protein in cerebrospinal spinal fluid (CSF). Brain MRI revealed bilateral cortical and striatal diffusion restriction and electroencephalogram (EEG) findings showed diffuse activity slowing with high amplitude sharp/slow-wave complexes. He was diagnosed with probable sporadic Creutzfeldt-Jakob disease (CJD) and management prioritised comfort and care. He passed away two weeks following admission and a mere 8 weeks after the first onset of symptoms.We present the first documented case of probable CJD with concomitant COVID-19 infection in the UK. We identified six other cases worldwide identified in our literature review. These cases suggest a role of COVID-19 in the rapid progression of CJD and add to the growing evidence of its neuroinflammatory role in other forms of neurodegenerative diseases.

The SARS-CoV-2 spike glycoprotein interacts with MAO-B and impairs mitochondrial energetics

SARS-CoV-2 infection is associated with both acute and post-acute neurological symptoms. Emerging evidence suggests that SARS-CoV-2 can alter mitochondrial metabolism, suggesting that changes in brain metabolism may contribute to the development of acute and post-acute neurological complications. Monoamine oxidase B (MAO-B) is a flavoenzyme located on the outer mitochondrial membrane that catalyzes the oxidative deamination of monoamine neurotransmitters. Computational analyses have revealed high similarity between the SARS-CoV-2 spike glycoprotein receptor binding domain on the ACE2 receptor and MAO-B, leading to the hypothesis that SARS-CoV-2 spike glycoprotein may alter neurotransmitter metabolism by interacting with MAO-B. Our results empirically establish that the SARS-CoV-2 spike glycoprotein interacts with MAO-B, leading to increased MAO-B activity in SH-SY5Y neuron-like cells. Common to neurodegenerative disease pathophysiological mechanisms, we also demonstrate that the spike glycoprotein impairs mitochondrial bioenergetics, induces oxidative stress, and perturbs the degradation of depolarized aberrant mitochondria through mitophagy. Our findings also demonstrate that SH-SY5Y neuron-like cells expressing the SARS-CoV-2 spike protein were more susceptible to MPTP-induced necrosis, likely necroptosis. Together, these results reveal novel mechanisms that may contribute to SARS-CoV-2-induced neurodegeneration.

De Novo Movement Disorders Associated with COVID-19- A Systematic Review of Individual Patients

Background

COVID-19 infection is associated with neurological manifestations, including various types of movement disorders (MD). A thorough review of individual patients with COVID-19-induced MD would help in better understanding the clinical profile and outcome of these patients and in prognostication.

Objective

We conducted an individual patient-systematic review to study the clinical and imaging profile and outcomes of patients with COVID-19-associated MD.

Methods

A systematic literature search of PubMed, EMBASE, and Cochrane databases was conducted by two independent reviewers. Individual patient data COVID from case reports and case series on COVID-19-associated MD, published between December 2019 and December 2022, were extracted and analyzed.

Results

Data of 133 patients with COVID-19-associated MD from 82 studies were analyzed. Mean age was 55 ± 18 years and 77% were males. A mixed movement disorder was most commonly seen (41%); myoclonus-ataxia was the most frequent (44.4%). Myoclonus significantly correlated with age (odds ratio (OR) 1.02 P = 0.03, CI 1-1.04). Tremor had the longest latency to develop after SARS-CoV-2 infection [median (IQR) 21 (10-40) days, P = 0.009, CI 1.01-1.05]. At short-term follow-up, myoclonus improved (OR 14.35, P value = 0.01, CI 1.71-120.65), whereas parkinsonism (OR 0.09, P value = 0.002, CI 0.19-0.41) and tremor (OR 0.16, P value = 0.016, CI 0.04-0.71) persisted.

Conclusion

Myoclonus-ataxia was the most common movement disorder after COVID-19 infection. Myoclonus was seen in older individuals and usually improved. Tremor and parkinsonism developed after a long latency and did not improve in the short-term.

Spike Protein Fragments Promote Alzheimer's Amyloidogenesis

Alzheimer's disease (AD) is a major cause of dementia inducing memory loss, cognitive decline, and mortality among the aging population. While the amyloid aggregation of peptide Aβ has long been implicated in neurodegeneration in AD, primarily through the production of toxic polymorphic aggregates and reactive oxygen species, viral infection has a less explicit role in the etiology of the brain disease. On the other hand, while the COVID-19 pandemic is known to harm human organs and function, its adverse effects on AD pathobiology and other human conditions remain unclear. Here we first identified the amyloidogenic potential of 1058HGVVFLHVTYV1068, a short fragment of the spike protein of SARS-CoV-2 coronavirus. The peptide fragment was found to be toxic and displayed a high binding propensity for the amyloidogenic segments of Aβ, thereby promoting the aggregation and toxicity of the peptide in vitro and in silico, while retarding the hatching and survival of zebrafish embryos upon exposure. Our study implicated SARS-CoV-2 viral infection as a potential contributor to AD pathogenesis, a little explored area in our quest for understanding and overcoming Long Covid.

SARS-CoV-2 drives NLRP3 inflammasome activation in human microglia through spike protein

Coronavirus disease-2019 (COVID-19) is primarily a respiratory disease, however, an increasing number of reports indicate that SARS-CoV-2 infection can also cause severe neurological manifestations, including precipitating cases of probable Parkinson's disease. As microglial NLRP3 inflammasome activation is a major driver of neurodegeneration, here we interrogated whether SARS-CoV-2 can promote microglial NLRP3 inflammasome activation. Using SARS-CoV-2 infection of transgenic mice expressing human angiotensin-converting enzyme 2 (hACE2) as a COVID-19 pre-clinical model, we established the presence of virus in the brain together with microglial activation and NLRP3 inflammasome upregulation in comparison to uninfected mice. Next, utilising a model of human monocyte-derived microglia, we identified that SARS-CoV-2 isolates can bind and enter human microglia in the absence of viral replication. This interaction of virus and microglia directly induced robust inflammasome activation, even in the absence of another priming signal. Mechanistically, we demonstrated that purified SARS-CoV-2 spike glycoprotein activated the NLRP3 inflammasome in LPS-primed microglia, in a ACE2-dependent manner. Spike protein also could prime the inflammasome in microglia through NF-κB signalling, allowing for activation through either ATP, nigericin or α-synuclein. Notably, SARS-CoV-2 and spike protein-mediated microglial inflammasome activation was significantly enhanced in the presence of α-synuclein fibrils and was entirely ablated by NLRP3-inhibition. Finally, we demonstrate SARS-CoV-2 infected hACE2 mice treated orally post-infection with the NLRP3 inhibitory drug MCC950, have significantly reduced microglial inflammasome activation, and increased survival in comparison with untreated SARS-CoV-2 infected mice. These results support a possible mechanism of microglial innate immune activation by SARS-CoV-2, which could explain the increased vulnerability to developing neurological symptoms akin to Parkinson's disease in COVID-19 infected individuals, and a potential therapeutic avenue for intervention.

Neurological manifestations of COVID-19: a systematic review and detailed comprehension

The current pandemic caused by severe acute respiratory syndrome corona virus 2 (SARS-CoV-2) is accompanied with a rapid increase of reports and papers detailing its neurological effects and symptoms. The virus infection causes respiratory illness named by the world health organization as corona virus 19 (COVID-19).This systematic review aims to study and summarize the different neurological manifestations of this virus. All articles published and indexed via Pubmed, Medline and Google Scholar databases between January 1st 2020 and February 28th 2021 that reported neurological symptoms of SARS-CoV-2 are reviewed following the Preferred Reporting Items for Systemic review and Meta-Analysis (PRISMA) guidelines.We included data from 113 articles: eight prospective studies, 25 retrospective studies and the rest were case reports/series. COVID-19 can present with central nervous system manifestations, such as headache, encephalitis and encephalopathy, peripheral nervous system manifestations, such as anosmia, ageusia and Guillian Barre syndrome, and skeletal muscle manifestations, such as myalgia and myasthenia gravis. Our systematic review showed that COVID-19 can be manifested by a wide spectrum of neurological symptoms reported either in the early stage or within the course of the disease. However, a detailed comprehension of these manifestations is required and more studies are needed in order to improve our scientific knowledge and to develop preventive and therapeutic measures to control this pandemic.

COVID-19 and neurological disorders: what might connect Parkinson's disease to SARS-CoV-2 infection

SARS-CoV-2 infection leading to Coronavirus disease 19 (COVID-19) rapidly became a worldwide health emergency due to its elevated infecting capacity, morbidity, and mortality. Parkinson’s disease (PD) is the second most common neurodegenerative disorder and, nowadays the relationship between SARS-CoV-2 outbreak and PD reached a great interest. Apparently independent one from the other, both diseases share some pathogenetic and clinical features. The relationship between SARS-CoV-2 infection and PD is complex and it depends on the direction of the association that is which of the two diseases comes first. Some evidence suggests that SARS-CoV-2 infection might be a possible risk factor for PD wherein the exposure to SARS-CoV-2 increase the risk for PD. This perspective comes out from the increasing cases of parkinsonism following COVID-19 and also from the anatomical structures affected in both COVID-19 and early PD such as olfactory bulb and gastrointestinal tract resulting in the same symptoms such as hyposmia and constipation. Furthermore, there are many reported cases of patients who developed hypokinetic extrapyramidal syndrome following SARS-CoV-2 infection although these would resemble a post-encephalitic conditions and there are to date relevant data to support the hypothesis that SARS-CoV-2 infection is a risk factor for the development of PD. Future large, longitudinal and population-based studies are needed to better assess whether the risk of developing PD after COVID-19 exists given the short time span from the starting of pandemic. Indeed, this brief time-window does not allow the precise estimation of the incidence and prevalence of PD after pandemic when compared with pre-pandemic era. If the association between SARS-CoV-2 infection and PD pathogenesis is actually putative, on the other hand, vulnerable PD patients may have a greater risk to develop COVID-19 being also more prone to develop a more aggressive disease course. Furthermore, PD patients with PD showed a worsening of motor and non-motor symptoms during COVID-19 outbreak due to both infection and social restriction. As well, the worries related to the risk of being infected should not be neglected. Here we summarize the current knowledge emerging about the epidemiological, pathogenetic and clinical relationship between SARS-CoV-2 infection and PD.

Clinical characteristics and outcome of COVID-19 patients with Parkinson's disease: a hospital-based case-control study in Shanghai, China

Background

Clinical manifestations of Parkinson's disease (PD) after Corona Virus Disease 2019 (COVID-19) infection are poorly investigated.

Objective

We aimed to explore the clinical features and outcomes of hospitalized PD patients with COVID-19.

Methods

A total of 48 PD patients and 96 age-and sex-matched non-PD patients were included. Demographics, clinical characteristics and outcomes were compared between two groups.

Results

PD patients with COVID-19 were elderly (76.69 ± 9.21 years) with advanced stage (H-Y stage 3-5 as 65.3%). They had less clinical symptoms (nasal obstruction, etc.), more proportions of severe/critical COVID-19 clinical classification (22.9 vs. 1.0%, p < 0.001), receiving oxygen (29.2 vs. 11.5%, p = 0.011), antibiotics (39.6 vs. 21.9%, p = 0.031) therapies, as well as longer hospitalization duration (11.39 vs. 8.32, p = 0.001) and higher mortality (8.3% vs. 1.0%, p = 0.001) relative to those without PD. Laboratory results showed that the PD group had higher white blood cell counts (6.29 vs. 5.16*109, p = 0.001), neutrophil-to-lymphocyte ratio (3.14 vs. 2.11, p < 0.001) and C-reactive protein level (12.34 vs. 3.19, p < 0.001).

Conclusion

PD patients with COVID-19 have insidious clinical manifestation, elevated proinflammatory markers and are prone to the development of severe/critical condition, contributing to a relatively poor prognosis. Early identification and active treatment of COVID-19 are pivotal to advanced PD patients during the pandemic.

Parkinson disease following COVID-19: Report of six cases

BACKGROUND AND PURPOSE

Core clinical manifestations of COVID-19 include influenza-like and respiratory symptoms. However, it is now evident that neurological involvement may occur during SARS-CoV-2 infection, covering an extensive spectrum of phenotypical manifestations. A major challenge arising from this pandemic is represented by detecting emerging neurological complications following recovery from SARS-CoV-2 infection. To date, a few post-COVID-19-infected subjects diagnosed with Parkinson disease (PD) have been described, raising the possibility of a connection between the infection and neurodegenerative processes. Here, we describe a case series of six subjects who developed PD after COVID-19.

METHODS

Patients were observed at Scientific Institute for Research and Health Care Mondino Foundation Hospital, Pavia (Italy), and San Paolo University Hospital of Milan (Italy) between March 2021 and June 2022. In all subjects, SARS-CoV-2 infection was confirmed by means of reverse transcriptase polymerase chain reaction from a nasopharyngeal swab. Subjects underwent an accurate neurological evaluation, and neuroimaging studies were performed.

RESULTS

We describe six subjects who developed PD with an average time window after SARS-CoV-2 infection of 4-7 weeks. Apparently, no relationship with COVID-19 severity emerged, and no overt structural brain abnormalities were found. All subjects experienced unilateral resting tremor at onset and showed a satisfactory response to dopaminergic treatment.

CONCLUSIONS

Immune responses to SARS-CoV-2 infection have been shown to shape the individual susceptibility to develop long-term consequences. We hypothesize that, in these subjects, COVID-19 has unmasked a latent neurodegenerative process. Characterization of the neuroinflammatory signatures in larger cohorts is warranted, which might provide novel insights into the pathogenesis of PD.

SARS-CoV-2, aging, and Post-COVID-19 neurodegeneration

As the world continues to experience the effects of SARS-CoV-2, there is evidence to suggest that the sequelae of viral infection (the post-COVID-19 condition; PCC) at both an individual and population level will be significant and long-lasting. The history of pandemics or epidemics in the last 100 years caused by members of the RNA virus family, of which coronaviruses are a member, provides ample evidence of the acute neurological effects. However, except for the H1N1 influenza pandemic of 1918/1919 (the Spanish flu) with its associated encephalitis lethargica, there is little information on long-term neurological sequelae. COVID-19 is the first pandemic that has occurred in a setting of an aging population, especially in several high-income countries. Its survivors are at the greatest risk for developing neurodegenerative conditions as they age, rendering the current pandemic a unique paradigm not previously witnessed. The SARS-CoV-2 virus, among the largest of the RNA viruses, is a single-stranded RNA that encodes for 29 proteins that include the spike protein that contains the key domains required for ACE2 binding, and a complex array of nonstructural proteins (NSPs) and accessory proteins that ensure the escape of the virus from the innate immune response, allowing for its efficient replication, translation, and exocytosis as a fully functional virion. Increasingly, these proteins are also recognized as potentially contributing to biochemical and molecular processes underlying neurodegeneration. In addition to directly being taken up by brain endothelium, the virus or key protein constituents can be transported to neurons, astrocytes, and microglia by extracellular vesicles and can accelerate pathological fibril formation. The SARS-CoV-2 nucleocapsid protein is intrinsically disordered and can participate in liquid condensate formation, including as pathological heteropolymers with neurodegenerative disease-associated RNA-binding proteins such as TDP-43, FUS, and hnRNP1A. As the SARS-CoV-2 virus continues to mutate under the immune pressure exerted by highly efficacious vaccines, it is evolving into a virus with greater transmissibility but less severity compared with the original strain. The potential of its lingering impact on the nervous system thus has the potential to represent an ongoing legacy of an even greater global health challenge than acute infection.

Parkinson's Disease, SARS-CoV-2, and Frailty: Is There a Vicious Cycle Related to Hypovitaminosis D?

The literature has long established the association between aging and frailty, with emerging evidence pointing to a relationship between frailty and SARS-CoV-2 contagion. The possible neurological consequences of SARS-CoV-2 infection, associated with physical and cognitive frailty, could lead to a worsening of Parkinson's disease (PD) in infected patients or-more rarely-to an increase in the Parkinsonian symptomatology. A possible link between those clinical pictures could be identified in vitamin D deficiency, while the whole process would appear to be associated with alterations in the microbiota-intestine-brain axis that fall within the α-Synuclein Origin site and Connectome (SOC) model, and allow for the identification of a body-first PD and a brain-first PD. The model of care for this condition must consider intrinsic and extrinsic variables so that care by a multidisciplinary team can be successfully predicted. A multidimensional screening protocol specifically designed to identify people at risk or in the early stages of the disease should begin with the investigation of indices of frailty and microbiota-intestine-brain axis alterations, with a new focus on cases of hypovitaminosis D.

Dopamine Transmission Imbalance in Neuroinflammation: Perspectives on Long-Term COVID-19

Dopamine (DA) is a key neurotransmitter in the basal ganglia, implicated in the control of movement and motivation. Alteration of DA levels is central in Parkinson’s disease (PD), a common neurodegenerative disorder characterized by motor and non-motor manifestations and deposition of alpha-synuclein (α-syn) aggregates. Previous studies have hypothesized a link between PD and viral infections. Indeed, different cases of parkinsonism have been reported following COVID-19. However, whether SARS-CoV-2 may trigger a neurodegenerative process is still a matter of debate. Interestingly, evidence of brain inflammation has been described in postmortem samples of patients infected by SARS-CoV-2, which suggests immune-mediated mechanisms triggering the neurological sequelae. In this review, we discuss the role of proinflammatory molecules such as cytokines, chemokines, and oxygen reactive species in modulating DA homeostasis. Moreover, we review the existing literature on the possible mechanistic interplay between SARS-CoV-2-mediated neuroinflammation and nigrostriatal DAergic impairment, and the cross-talk with aberrant α-syn metabolism.

Gastrointestinal, Respiratory, and Olfactory Neurotropism of Sars-Cov2 as a Possible Trigger of Parkinson's Disease: Is a Multi-Hit Multi-Step Process on the Cards

Since the first emergence of COVID-19 on the global stage, there has been a wealth of evidence to suggest that SARS-Cov2 is not merely a pulmonary pathogen. This virus is unique in its ability to disrupt cellular pathways related to protein homeostasis, mitochondrial function, stress response, and aging. Such effects raise concerns about the long-term fate of survivors of COVID-19 infection, particularly regarding neurodegenerative diseases. The concept of interaction between environmental factors and alpha-synuclein formation in the olfactory bulb and vagal autonomic terminals with subsequent caudo-cranial migration has received much attention in the context of PD pathogenesis. Anosmia and gastrointestinal symptoms are two well-known symptoms of COVID-19, with evidence of an olfactory bulb and vagal infiltration by SARS-CoV2. This raises the possibility of the spread of the viral particles to the brain along multiple cranial nerve routes. Neurotropism, coupled with the ability of the SARS-Cov2 virion to induce abnormal protein folding and stress responses in the central nervous system, in presence of an inflammatory milieu, reinforced by hypoxia, coagulopathy, and endothelial dysfunction, reverberates the intriguing possibility of activation of a neurodegenerative cascade leading to the development of pathological alpha-synuclein aggregates and thus, triggering the development of PD in survivors of COVID19. This review attempts to summarize and critically appraise existing evidence from basic science research and clinical reports of links between COVID-19 and PD and explores the prospect of a multi-hit pathophysiological process, induced by SARS-Cov2 infection, ultimately converging on perturbed cellular protein homeostasis, which although is intriguing, presently lacks robust evidence for confirmation.

Continuous population-level monitoring of SARS-CoV-2 seroprevalence in a large European metropolitan region

Effective public health measures against SARS-CoV-2 require granular knowledge of population-level immune responses. We developed a Tripartite Automated Blood Immunoassay (TRABI) to assess the IgG response against three SARS-CoV-2 proteins. We used TRABI for continuous seromonitoring of hospital patients and blood donors (n = 72'250) in the canton of Zurich from December 2019 to December 2020 (pre-vaccine period). We found that antibodies waned with a half-life of 75 days, whereas the cumulative incidence rose from 2.3% in June 2020 to 12.2% in mid-December 2020. A follow-up health survey indicated that about 10% of patients infected with wildtype SARS-CoV-2 sustained some symptoms at least twelve months post COVID-19. Crucially, we found no evidence of a difference in long-term complications between those whose infection was symptomatic and those with asymptomatic acute infection. The cohort of asymptomatic SARS-CoV-2-infected subjects represents a resource for the study of chronic and possibly unexpected sequelae.

Appearance of extrapyramidal symptoms in adolescent psychiatry patients during COVID-19 infection

Since the start of the pandemic, there has been an increase in the incidence of psychiatric morbidity among those infected with coronavirus disease 2019 (COVID-19) and those indirectly affected by COVID-19. There has been a considerable increase in the number of individuals with such psychiatric conditions as depression, acute stress disorders, anxiety, and posttraumatic stress disorder (PTSD). About one-third of patients with COVID-19 are reported to have developed short and long-term neuropsychiatric conditions such as delirium, agitation, altered consciousness, hypoxic encephalopathy encephalitis, dysexecutive syndrome, cerebrovascular complications (e.g., stroke), hypoxic encephalopathy, convulsions, neuromuscular dysfunction, demyelinating processes, or parkinsonism through several pathophysiological mechanisms. Nevertheless, as the pandemic progressed, data on neuropsychiatric manifestations implied that the pathologic capacity of COVID-19 and its association with the onset and/or exacerbation of psychiatric morbidity indicate that COVID-19 is potentially related to neuropsychiatric involvement. Patients with existing mental disorders under psychotropic treatment exposed to the COVID-19 infection have been represented by an increased risk of worsened psychiatric symptoms and expanded drug side effects. The present study aimed to describe five pediatric patients with various psychiatric illness that experienced COVID-19 infection and had potentially associated neuropsychiatric involvement, such as exacerbation of underlying psychiatric symptoms and extrapyramidal side effects. To the best of our knowledge, the present study is the first to describe adolescents with COVID-19 infection that presented with a series of manifestations in the form of an increase in extrapyramidal symptoms (EPS)  during exacerbation of underlying psychiatric disease.

NLRP3 inflammasome in neurodegenerative disease

Neurodegenerative diseases are characterized by a dysregulated neuro-glial microenvironment, culminating in functional deficits resulting from neuronal cell death. Inflammation is a hallmark of the neurodegenerative microenvironment and despite a critical role in tissue homeostasis, increasing evidence suggests that chronic inflammatory insult can contribute to progressive neuronal loss. Inflammation has been studied in the context of neurodegenerative disorders for decades but few anti-inflammatory treatments have advanced to clinical use. This is likely due to the related challenges of predicting and mitigating off-target effects impacting the normal immune response while detecting inflammatory signatures that are specific to the progression of neurological disorders. Inflammasomes are pro-inflammatory cytosolic pattern recognition receptors functioning in the innate immune system. Compelling pre-clinical data has prompted an intense interest in the role of the NLR family pyrin domain containing 3 (NLRP3) inflammasome in neurodegenerative disease. NLRP3 is typically inactive but can respond to sterile triggers commonly associated with neurodegenerative disorders including protein misfolding and aggregation, mitochondrial and oxidative stress, and exposure to disease-associated environmental toxicants. Clear evidence of enhanced NLRP3 inflammasome activity in common neurodegenerative diseases has coincided with rapid advancement of novel small molecule therapeutics making the NLRP3 inflammasome an attractive target for near-term interventional studies. In this review, we highlight evidence from model systems and patients indicating inflammasome activity in neurodegenerative disease associated with the NLRP3 inflammasome's ability to recognize pathologic forms of amyloid-β, tau, and α-synuclein. We discuss inflammasome-driven pyroptotic processes highlighting the potential utility of evaluating extracellular inflammasome-related proteins in the context of biomarker discovery. We complete the report by pointing out gaps in our understanding of intracellular modifiers of inflammasome activity and mechanisms regulating the resolution of inflammasome activation. The literature review and perspectives provide a conceptual platform for continued analysis of inflammation in neurodegenerative diseases through the study of inflammasomes and pyroptosis, mechanisms of inflammation and cell death now recognized to function in multiple highly prevalent neurological disorders.

Links between COVID-19 and Parkinson's disease/Alzheimer's disease: reciprocal impacts, medical care strategies and underlying mechanisms

The impact of coronavirus disease 2019 (COVID-19) pandemic on patients with neurodegenerative diseases and the specific neurological manifestations of COVID-19 have aroused great interest. However, there are still many issues of concern to be clarified. Therefore, we review the current literature on the complex relationship between COVID-19 and neurodegenerative diseases with an emphasis on Parkinson's disease (PD) and Alzheimer's disease (AD). We summarize the impact of COVID-19 infection on symptom severity, disease progression, and mortality rate of PD and AD, and discuss whether COVID-19 infection could trigger PD and AD. In addition, the susceptibility to and the prognosis of COVID-19 in PD patients and AD patients are also included. In order to achieve better management of PD and AD patients, modifications of care strategies, specific drug therapies, and vaccines during the pandemic are also listed. At last, mechanisms underlying the link of COVID-19 with PD and AD are reviewed.

Genetic Predisposition to Neurological Complications in Patients with COVID-19

Several studies have identified rare and common genetic variants associated with severe COVID-19, but no study has reported genetic determinants as predisposition factors for neurological complications. In this report, we identified rare/unique structural variants (SVs) implicated in neurological functions in two individuals with neurological manifestations of COVID-19. This report highlights the possible genetic link to the neurological symptoms with COVID-19 and calls for a collective effort to study these cohorts for a possible genetic linkage.

Amyloid Protein Cross-Seeding Provides a New Perspective on Multiple Diseases In Vivo

Amyloid protein cross-seeding is a peculiar phenomenon of cross-spreading among different diseases. Unlike traditional infectious ones, diseases caused by amyloid protein cross-seeding are spread by misfolded proteins instead of pathogens. As a consequence of the interactions among misfolded heterologous proteins or polypeptides, amyloid protein cross-seeding is considered to be the crucial cause of overlapping pathological transmission between various protein misfolding disorders (PMDs) in multiple tissues and cells. Here, we briefly review the phenomenon of cross-seeding among amyloid proteins. As an interesting example worth mentioning, the potential links between the novel coronavirus pneumonia (COVID-19) and some neurodegenerative diseases might be related to the amyloid protein cross-seeding, thus may cause an undesirable trend in the incidence of PMDs around the world. We then summarize the theoretical models as well as the experimental techniques for studying amyloid protein cross-seeding. Finally, we conclude with an outlook on the challenges and opportunities for basic research in this field. Cross-seeding of amyloid opens up a new perspective in our understanding of the process of amyloidogenesis, which is crucial for the development of new treatments for diseases. It is therefore valuable but still challenging to explore the cross-seeding system of amyloid protein as well as to reveal the structural basis and the intricate processes.

Are patients with Parkinson's disease at a lower risk of catching the common cold? Propensity score matching

INTRODUCTION

Accumulating evidence indicating that inflammatory responses play crucial roles in Parkinson's disease (PD) development provided a hypothesis that physiological alpha-synuclein may contribute to inflammatory responses against infections during non-advanced stages of PD. Thus, we examined the risk of catching a common cold in patients with PD as compared to other common brain diseases.

METHODS

We extracted PD (non-advanced; without dementia) and control (AD: Alzheimer's disease, migraine, epilepsy, and ischemic stroke) patient data from insurance claim data available between 2010 and 2021. After confirming the clinical PD diagnosis, we investigated factors associated with cold diagnoses and used propensity score matching to identify differences in the incidence of colds between PD and control patients.

RESULTS

Diagnosis of colds in PD patients (n = 726) and controls (AD = 377, migraine = 1019, epilepsy = 3414, ischemic stroke = 6943) was found in 1186 (9.5%) patients, which was independently associated with being female (odds ratio: OR 1.59; 95%CI 1.41-1.79; P < 0.0001), follow-up by neurologists (OR 1.30; 95%CI 1.15-1.48; P < 0.0001), diagnosis of PD (OR 0.30; 95%CI 0.20-0.45; P < 0.0001) and COVID-19 pandemic period (OR 0.58; 95%CI 0.47-0.72; P < 0.0001). After propensity score matching, the incidence of colds was significantly lower in PD (3.4%) versus in controls; AD (9.8%; P < 0.0001), migraine (13.3%; P < 0.0001), epilepsy (11.0%; P < 0.0001), ischemic stroke (8.8%; P < 0.0001).

CONCLUSIONS

Patients with PD were less likely to be diagnosed with colds. However, several confounding factors will need to be examined. Moreover, alpha-synuclein may provide protective resistance to viral infections by activating the immune system due to chronic inflammation in non-advanced PD patients.

How Toll-like receptors influence Parkinson's disease in the microbiome-gut-brain axis

Recently, a large number of experimenters have found that the pathogenesis of Parkinson's disease may be related to the gut microbiome and proposed the microbiome-gut-brain axis. Studies have shown that Toll-like receptors, especially Toll-like receptor 2 (TLR2) and Toll-like receptor 4 (TLR4), are key mediators of gut homeostasis. In addition to their established role in innate immunity throughout the body, research is increasingly showing that the Toll-like receptor 2 and Toll-like receptor 4 signaling pathways shape the development and function of the gut and enteric nervous system. Notably, Toll-like receptor 2 and Toll-like receptor 4 are dysregulated in Parkinson's disease patients and may therefore be identified as the core of early gut dysfunction in Parkinson's disease. To better understand the contribution of Toll-like receptor 2 and Toll-like receptor 4 dysfunction in the gut to early α-synuclein aggregation, we discussed the structural function of Toll-like receptor 2 and Toll-like receptor 4 and signal transduction of Toll-like receptor 2 and Toll-like receptor 4 in Parkinson's disease by reviewing clinical, animal models, and in vitro studies. We also present a conceptual model of the pathogenesis of Parkinson's disease, in which microbial dysbiosis alters the gut barrier as well as the Toll-like receptor 2 and Toll-like receptor 4 signaling pathways, ultimately leading to a positive feedback loop for chronic gut dysfunction, promoting α-synuclein aggregation in the gut and vagus nerve.

Steroid administration for post-COVID-19 Parkinsonism: A case report

A 45-year-old man developed parkinsonism 3 weeks after being diagnosed with mild COVID-19. Levodopa and benserazide failed to improve his symptoms, necessitating ropinirole, and steroid treatment, which included a 5-day course of methylprednisolone followed by a 3-month oral prednisolone taper. One month after initiating steroid treatment, his symptoms improved significantly.

Investigating neurological symptoms of infectious diseases like COVID-19 leading to a deeper understanding of neurodegenerative disorders such as Parkinson's disease

Apart from common respiratory symptoms, neurological symptoms are prevalent among patients with COVID-19. Research has shown that infection with SARS-CoV-2 accelerated alpha-synuclein aggregation, induced Lewy-body-like pathology, caused dopaminergic neuron senescence, and worsened symptoms in patients with Parkinson's disease (PD). In addition, SARS-CoV-2 infection can induce neuroinflammation and facilitate subsequent neurodegeneration in long COVID, and increase individual vulnerability to PD or parkinsonism. These findings suggest that a post-COVID-19 parkinsonism might follow the COVID-19 pandemic. In order to prevent a possible post-COVID-19 parkinsonism, this paper reviewed neurological symptoms and related findings of COVID-19 and related infectious diseases (influenza and prion disease) and neurodegenerative disorders (Alzheimer's disease, PD and amyotrophic lateral sclerosis), and discussed potential mechanisms underlying the neurological symptoms and the relationship between the infectious diseases and the neurodegenerative disorders, as well as the therapeutic and preventive implications in the neurodegenerative disorders. Infections with a relay of microbes (SARS-CoV-2, influenza A viruses, gut bacteria, etc.) and prion-like alpha-synuclein proteins over time may synergize to induce PD. Therefore, a systematic approach that targets these pathogens and the pathogen-induced neuroinflammation and neurodegeneration may provide cures for neurodegenerative disorders. Further, antiviral/antimicrobial drugs, vaccines, immunotherapies and new therapies (e.g., stem cell therapy) need to work together to treat, manage or prevent these disorders. As medical science and technology advances, it is anticipated that better vaccines for SARS-CoV-2 variants, new antiviral/antimicrobial drugs, effective immunotherapies (alpha-synuclein antibodies, vaccines for PD or parkinsonism, etc.), as well as new therapies will be developed and made available in the near future, which will help prevent a possible post-COVID-19 parkinsonism in the 21st century.

Discovering Common Pathogenic Mechanisms of COVID-19 and Parkinson Disease: An Integrated Bioinformatics Analysis

Coronavirus disease 2019 (COVID-19) has emerged since December 2019 and was later characterized as a pandemic by WHO, imposing a major public health threat globally. Our study aimed to identify common signatures from different biological levels to enlighten the current unclear association between COVID-19 and Parkinson's disease (PD) as a number of possible links, and hypotheses were reported in the literature. We have analyzed transcriptome data from peripheral blood mononuclear cells (PBMCs) of both COVID-19 and PD patients, resulting in a total of 81 common differentially expressed genes (DEGs). The functional enrichment analysis of common DEGs are mostly involved in the complement system, type II interferon gamma (IFNG) signaling pathway, oxidative damage, microglia pathogen phagocytosis pathway, and GABAergic synapse. The protein-protein interaction network (PPIN) construction was carried out followed by hub detection, revealing 10 hub genes (MX1, IFI27, C1QC, C1QA, IFI6, NFIX, C1S, XAF1, IFI35, and ELANE). Some of the hub genes were associated with molecular mechanisms such as Lewy bodies-induced inflammation, microglia activation, and cytokine storm. We investigated regulatory elements of hub genes at transcription factor and miRNA levels. The major transcription factors regulating hub genes are SOX2, XAF1, RUNX1, MITF, and SPI1. We propose that these events may have important roles in the onset or progression of PD. To sum up, our analysis describes possible mechanisms linking COVID-19 and PD, elucidating some unknown clues in between.

A comprehensive mini-review on amyloidogenesis of different SARS-CoV-2 proteins and its effect on amyloid formation in various host proteins

Amyloidogenesis is the inherent ability of proteins to change their conformation from native state to cross β-sheet rich fibrillar structures called amyloids which result in a wide range of diseases like Parkinson's disease, Alzheimer's disease, Finnish familial amyloidosis, ATTR amyloidosis, British and Danish dementia, etc. COVID-19, on the other hand is seen to have many similarities in symptoms with other amyloidogenic diseases and the overlap of these morbidities and symptoms led to the proposition whether SARS-CoV-2 proteins are undergoing amyloidogenesis and whether it is resulting in or aggravating amyloidogenesis of any human host protein. Thus the SARS-CoV-2 proteins in infected cells, i.e., Spike (S) protein, Nucleocapsid (N) protein, and Envelope (E) protein were tested via different machinery and amyloidogenesis in them were proven. In this review, we will analyze the pathway of amyloid formation in S-protein, N-protein, E-protein along with the effect that SARS-CoV-2 is creating on various host proteins leading to the unexpected onset of many morbidities like COVID-induced Acute Respiratory Distress Syndrome (ARDS), Parkinsonism in young COVID patients, formation of fibrin microthrombi in heart, etc., and their future implications.

Pharmacological Potential of Flavonoids against Neurotropic Viruses

Flavonoids are a group of natural compounds that have been described in the literature as having anti-inflammatory, antioxidant, and neuroprotective compounds. Although they are considered versatile molecules, little has been discussed about their antiviral activities for neurotropic viruses. Hence, the present study aimed to investigate the pharmacological potential of flavonoids in the face of viruses that can affect the central nervous system (CNS). We carried out research from 2011 to 2021 using the Pubmed platform. The following were excluded: articles not in the English language, letters to editors, review articles and papers that did not include any experimental or clinical tests, and papers that showed antiviral activities against viruses that do not infect human beings. The inclusion criteria were in silico predictions and preclinical pharmacological studies, in vitro, in vivo and ex vivo, and clinical studies with flavonoids, flavonoid fractions and extracts that were active against neurotropic viruses. The search resulted in 205 articles that were sorted per virus type and discussed, considering the most cited antiviral activities. Our investigation shows the latest relevant data about flavonoids that have presented a wide range of actions against viruses that affect the CNS, mainly influenza, hepatitis C and others, such as the coronavirus, enterovirus, and arbovirus. Considering that these molecules present well-known anti-inflammatory and neuroprotective activities, using flavonoids that have demonstrated both neuroprotective and antiviral effects could be viewed as an alternative for therapy in the course of CNS infections.

Cytokine storm and neuropathological alterations in patients with neurological manifestations of COVID-19

The COVID-19 pandemic is caused by the severe acute respiratory syndrome coronavirus (SARS-CoV-2), a respiratory pathogen with neuroinvasive potential. Neurological COVID-19 manifestations include loss of smell and taste, headache, dizziness, stroke, and potentially fatal encephalitis. Several studies found elevated proinflammatory cytokines such as TNF-α, IFN-γ, IL-6 IL-8, IL-10 IL-16, IL-17A, and IL-18 in severely and critically ill COVID-19 patients, which may persist even after apparent recovery from infection. Biomarker studies on CSF and plasma and serum from COVID-19 patients have also shown a high level of IL-6, intrathecal IgG, neurofilament light chain (NFL), glial fibrillary acidic protein (GFAP), and tau protein. Emerging evidence on the matter has established the concept of COVID-19 associated neuroinflammation, in the context of COVID-19 associated cytokine storm. While the short-term implications of this condition are extensively documented, its long-term implications are yet to be understood. The association of the aforementioned cytokines with the pathogenesis of neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, Huntington disease, and amyotrophic lateral sclerosis, may increase COVID-19 patients' risk to develop neurodegenerative diseases. Analysis of proinflammatory cytokines and CSF biomarkers in patients with COVID-19 can contribute to the early detection of the disease's exacerbation, monitoring the neurological implications of the disease and devising risk scales, and identifying treatment targets.

Viruses, parkinsonism and Parkinson's disease: the past, present and future

Parkinsonism secondary to viral infections is not an uncommon occurrence and has been brought under the spotlight with the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. A variety of viruses have been described with a potential of inducing or contributing to the occurrence of parkinsonism and Parkinson's disease (PD), although the relationship between the two remains a matter of debate originating with the description of encephalitis lethargica in the aftermath of the Spanish flu in 1918. While some viral infections have been linked to an increased risk for the development of PD, others seem to have a causal link with the occurrence of parkinsonism. Here, we review the currently available evidence on viral-induced parkinsonism with a focus on potential pathophysiological mechanisms and clinical features. We also review the evidence on viral infections as a risk factor for developing PD and the link between SARS-CoV-2 and parkinsonism, which might have important implications for future research and treatments.

Post-COVID-19 Parkinsonism and Parkinson's Disease Pathogenesis: The Exosomal Cargo Hypothesis

Parkinson's disease (PD) is the second most prevalent neurodegenerative disease after Alzheimer's disease, globally. Dopaminergic neuron degeneration in substantia nigra pars compacta and aggregation of misfolded alpha-synuclein are the PD hallmarks, accompanied by motor and non-motor symptoms. Several viruses have been linked to the appearance of a post-infection parkinsonian phenotype. Coronavirus disease 2019 (COVID-19), caused by emerging severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection, has evolved from a novel pneumonia to a multifaceted syndrome with multiple clinical manifestations, among which neurological sequalae appear insidious and potentially long-lasting. Exosomes are extracellular nanovesicles bearing a complex cargo of active biomolecules and playing crucial roles in intercellular communication under pathophysiological conditions. Exosomes constitute a reliable route for misfolded protein transmission, contributing to PD pathogenesis and diagnosis. Herein, we summarize recent evidence suggesting that SARS-CoV-2 infection shares numerous clinical manifestations and inflammatory and molecular pathways with PD. We carry on hypothesizing that these similarities may be reflected in exosomal cargo modulated by the virus in correlation with disease severity. Travelling from the periphery to the brain, SARS-CoV-2-related exosomal cargo contains SARS-CoV-2 RNA, viral proteins, inflammatory mediators, and modified host proteins that could operate as promoters of neurodegenerative and neuroinflammatory cascades, potentially leading to a future parkinsonism and PD development.

Covid-19 and Parkinson's disease: Acute clinical implications, long-COVID and post-COVID-19 parkinsonism

The Coronavirus Disease 2019 (Covid-19), caused by the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), has led to unprecedented challenges for the delivery of healthcare and has had a clear impact on people with chronic neurological conditions such as Parkinson's disease (PD). Acute worsening of motor and non-motor symptoms and long-term sequalae have been described during and after SARS-CoV-2 infections in people with Parkinson's (PwP), which are likely to be multifactorial in their origin. On the one hand, it is likely that worsening of symptoms has been related to the viral infection itself, whereas social restrictions imposed over the course of the Covid-19 pandemic might also have had such an effect. Twenty cases of post-Covid-19 para-infectious or post-infectious parkinsonism have been described so far where a variety of pathophysiological mechanisms seem to be involved; however, a Covid-19-induced wave of post-viral parkinsonism seems rather unlikely at the moment. Here, we describe the interaction between SARS-CoV-2 and PD in the short- and long-term and summarize the clinical features of post-Covid-19 cases of parkinsonism observed so far.

SARS-CoV-2 impairs the disassembly of stress granules and promotes ALS-associated amyloid aggregation

The nucleocapsid (N) protein of SARS-CoV-2 has been reported to have a high ability of liquid-liquid phase separation, which enables its incorporation into stress granules (SGs) of host cells. However, whether SG invasion by N protein occurs in the scenario of SARS-CoV-2 infection is unknow, neither do we know its consequence. Here, we used SARS-CoV-2 to infect mammalian cells and observed the incorporation of N protein into SGs, which resulted in markedly impaired self-disassembly but stimulated cell cellular clearance of SGs. NMR experiments further showed that N protein binds to the SG-related amyloid proteins via non-specific transient interactions, which not only expedites the phase transition of these proteins to aberrant amyloid aggregation in vitro, but also promotes the aggregation of FUS with ALS-associated P525L mutation in cells. In addition, we found that ACE2 is not necessary for the infection of SARS-CoV-2 to mammalian cells. Our work indicates that SARS-CoV-2 infection can impair the disassembly of host SGs and promote the aggregation of SG-related amyloid proteins, which may lead to an increased risk of neurodegeneration.

New-onset Parkinsonism as a Covid-19 infection sequela: A systematic review and meta-analysis

Background

There remains a scarcity of literature regarding COVID-19 and its neurological sequelae. This study highlights Parkinsonism as a post-COVID-19 sequela and helps us understand a possible link between the two.

Methods

A literature search covering relevant databases was conducted for studies reporting the development of Parkinsonism in patients recovering from COVID-19 infection. A quality assessment tool developed by The Joanna Briggs Institute Critical Appraisal tools for the assessment of case reports was utilized. Fisher's exact test was used to explore the factors associated with COVID-19 and Parkinsonism as its complication.

Results

Ten studies were included in our study. The median age of patients was 60.0, with an interquartile range of 42.5–72.0. There were 8 males (61.5%) patients, and 53.8% of cases were reported to have at least one comorbidity. Cogwheel rigidity was the most common symptom of Parkinsonism in 11 patients. While the most standard treatment modality used was Levodopa in 76.9% of cases. Using the Fisher's Exact test, it was identified that 10 patients (76.9%) with bradykinesia made a full recovery.

Conclusion

Despite presumed “recovery” from COVID-19, patients still face a wide range of neurological complications. One of these complications presenting as Parkinsonism requires health care professionals to be on the lookout for the long-term effects of COVID-19. Hence, our study provides information on the possible likely hood of a link between COVID-19 and the development of Parkinsonism as post-COVID neurological sequelae.

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There have been well-documented reports about the occurrence of parkinsonism after viral infections.

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10 studies including 13 patients reported the development of parkinsonism in individuals who recovered from COVID-19 infection.

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The commonest symptom of parkinsonism reported in these individuals was cogwheel rigidity 84.6%.

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53.8% of individuals fully recovered and had their symptoms resolved after treatment.