Viral parkinsonism

Manganese exposure in juvenile C57BL/6 mice increases glial inflammatory responses in the substantia nigra following infection with H1N1 influenza virus

Infection with Influenza A virus can lead to the development of encephalitis and subsequent neurological deficits ranging from headaches to neurodegeneration. Post-encephalitic parkinsonism has been reported in surviving patients of H1N1 infections, but not all cases of encephalitic H1N1 infection present with these neurological symptoms, suggesting that interactions with an environmental neurotoxin could promote more severe neurological damage. The heavy metal, manganese (Mn), is a potential interacting factor with H1N1 because excessive exposure early in life can induce long-lasting effects on neurological function through inflammatory activation of glial cells. In the current study, we used a two-hit model of neurotoxin-pathogen exposure to examine whether exposure to Mn during juvenile development would induce a more severe neuropathological response following infection with H1N1 in adulthood. To test this hypothesis, C57BL/6 mice were exposed to MnCl₂ in drinking water (50 mg/kg/day) for 30 days from days 21–51 postnatal, then infected intranasally with H1N1 three weeks later. Analyses of dopaminergic neurons, microglia and astrocytes in basal ganglia indicated that although there was no significant loss of dopaminergic neurons within the substantia nigra pars compacta, there was more pronounced activation of microglia and astrocytes in animals sequentially exposed to Mn and H1N1, as well as altered patterns of histone acetylation. Whole transcriptome Next Generation Sequencing (RNASeq) analysis was performed on the substantia nigra and revealed unique patterns of gene expression in the dual-exposed group, including genes involved in antioxidant activation, mitophagy and neurodegeneration. Taken together, these results suggest that exposure to elevated levels of Mn during juvenile development could sensitize glial cells to more severe neuro-immune responses to influenza infection later in life through persistent epigenetic changes.

COVID-19 and Body Iron: A Survey on Phenomenological and Genetic Correlations

To provide solid information about viral infection, disease, and body iron metabolism, the literature was surveyed for mutual correlations. Gender and age profiles of COVID-19 infection and disease correlate well with the profiles of serum iron and ferritin with correlation coefficients ≥ 0.75. There are further symptomatic hints that the ABO blood group system contributes to these correlations. Remarkably, the susceptibility to both the viral disease and iron dyshomeostasis can be traced back to the same gene loci of the ABO blood group system. The overlapping of susceptible gene loci together with the phenomenological correlations in gender and age are strong indicators for the interrelation of body iron dyshomeostasis with COVID-19 infection and disease.

Viruses as 'Truffle Hounds': Molecular Tools for Untangling Brain Cellular Pathology

The ability of viruses to evolve several orders of magnitude faster than their host cells has enabled them to exploit host cellular machinery by selectively recruiting multiprotein complexes (MPCs) for their catalyzed assembly and replication. This hijacking may depend on alternative, 'moonlighting' functions of host proteins that deviate from their canonical functions thereby inducing cellular pathology. Here, we posit that if virus-induced cellular pathology is similar to that of other, unknown (non-viral) causes, the identification and molecular characterization of the host proteins involved in virus-mediated cellular pathology can be leveraged to decipher the non-viral disease-relevant mechanisms. We focus on how virus-induced aberrant proteostasis and protein aggregation resemble the cellular pathology of sporadic neurodegenerative diseases (NDs) and how this can be exploited for drug discovery.

CNS implications of COVID-19: a comprehensive review

COVID-19 was first reported in December 2019 in the Wuhan city of China, and since then it has spread worldwide taking a heavy toll on human life and economy. COVID-19 infection is commonly associated with symptoms like coughing, fever, and shortness of breath, besides, the reports of muscle pain, anosmia, hyposmia, and loss of taste are becoming evident. Recent reports suggest the pathogenic invasion of the SARS-CoV-2 into the CNS, that could thereby result in devastating long term complications, primarily because some of these complications may go unnoticed for a long time. Evidence suggest that the virus could enter the CNS through angiotensin-converting enzyme-2 (ACE-2) receptor, neuronal transport, haematogenous route, and nasal route via olfactory bulb, cribriform plate, and propagates through trans-synaptic signalling, and shows retrograde movement into the CNS along nerve fiber. COVID-19 induces CNS inflammation and neurological degenerative damage through a diverse mechanism which includes ACE-2 receptor damage, cytokine-associated injury or cytokine storm syndrome, secondary hypoxia, demyelination, blood-brain barrier disruption, neurodegeneration, and neuroinflammation. Viral invasion into the CNS has been reported to show association with complications like Parkinsonism, Alzheimer's disorder, meningitis, encephalopathy, anosmia, hyposmia, anxiety, depression, psychiatric symptoms, seizures, stroke, etc. This review provides a detailed discussion of the CNS pathogenesis of COVID-19. Authors conclude that the COVID-19 cannot just be considered as a disorder of the pulmonary or peripheral system, rather it has a significant CNS involvement. Therefore, CNS aspects of the COVID-19 should be monitored very closely to prevent long term CNS complications, even after the patient has recovered from COVID-19.

Type B coxsackieviruses and central nervous system disorders: critical review of reported associations

Type B coxsackieviruses (CV-B) frequently infect the central nervous system (CNS) causing neurological diseases notably meningitis and encephalitis. These infections occur principally among newborns and children. Epidemiological studies of patients with nervous system disorders demonstrate the presence of infectious virus, its components, or anti-CV-B antibodies. Some experimental studies conducted in vitro and in vivo support the potential association between CV-B and idiopathic neurodegenerative diseases such as amyotrophic lateral sclerosis and psychiatric illness such as schizophrenia. However, mechanisms explaining how CV-B infections may contribute to the genesis of CNS disorders remain unclear. The proposed mechanisms focus on the immune response following the viral infection as a contributor to pathogenesis. This review describes these epidemiological and experimental studies, the modes of transmission of CV-B with an emphasis on congenital transmission, the routes used by CV-B to reach the brain parenchyma, and plausible mechanisms by which CV-B may induce CNS diseases, with a focus on potential immunopathogenesis.

Microorganisms that are related with increased risk for Parkinson's disease

Parkinson's disease is a neurodegenerative disorder that affects more than 7 million people worldwide. Its aetiology is unknown, although the hypothesis of a genetic susceptibility to environmental agents is accepted. These environmental agents include fungi, bacteria, and viruses. Three microorganisms are directly associated with a significantly increased risk of developing Parkinson's disease: the fungal genus Malassezia, the bacterium Helicobacter pylori, and the hepatitis C virus. If the host is vulnerable due to genetic susceptibility or immune weakness, these microorganisms can access and infect the nervous system, causing chronic neuroinflammation with neurodegeneration. Other microorganisms show an epidemiological association with the disease, including the influenza type A, Japanese encephalitis type B, St Louis, and West Nile viruses. These viruses can affect the nervous system, causing encephalitis, which can result in parkinsonism. This article reviews the role of all these microorganisms in Parkinson's disease.

Severe acute respiratory syndrome coronavirus 2 may be an underappreciated pathogen of the central nervous system

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causes a highly contagious respiratory disease referred to as COVID-19. However, emerging evidence indicates that a small but growing number of COVID-19 patients also manifest neurological symptoms, suggesting that SARS-CoV-2 may infect the nervous system under some circumstances. SARS-CoV-2 primarily enters the body through the epithelial lining of the respiratory and gastrointestinal tracts, but under certain conditions this pleiotropic virus may also infect peripheral nerves and gain entry into the central nervous system (CNS). The brain is shielded by various anatomical and physiological barriers, most notably the blood-brain barrier (BBB) which functions to prevent harmful substances, including pathogens and pro-inflammatory mediators, from entering the brain. The BBB is composed of highly specialized endothelial cells, pericytes, mast cells and astrocytes that form the neurovascular unit, which regulates BBB permeability and maintains the integrity of the CNS. In this review, potential routes of viral entry and the possible mechanisms utilized by SARS-CoV-2 to penetrate the CNS, either by disrupting the BBB or infecting the peripheral nerves and using the neuronal network to initiate neuroinflammation, are briefly discussed. Furthermore, the long-term effects of SARS-CoV-2 infection on the brain and in the progression of neurodegenerative diseases known to be associated with other human coronaviruses are considered. Although the mechanisms of SARS-CoV-2 entry into the CNS and neurovirulence are currently unknown, the potential pathways described here might pave the way for future research in this area and enable the development of better therapeutic strategies.

Neurological complications of coronavirus infection; a comparative review and lessons learned during the COVID-19 pandemic

INTRODUCTION

Coronavirus disease-19 (COVID-19) pandemic continues to grow all over the world. Several studies have been performed, focusing on understanding the acute respiratory syndrome and treatment strategies. However, there is growing evidence indicating neurological manifestations occur in patients with COVID-19. Similarly, the other coronaviruses (CoV) epidemics; severe acute respiratory syndrome (SARS-CoV-1) and Middle East respiratory syndrome (MERS-CoV) have been associated with neurological complications.

METHODS

This systematic review serves to summarize available information regarding the potential effects of different types of CoV on the nervous system and describes the range of clinical neurological complications that have been reported thus far in COVID-19.

RESULTS

Two hundred and twenty-five studies on CoV infections associated neurological manifestations in human were reviewed. Of those, 208 articles were pertinent to COVID-19. The most common neurological complaints in COVID-19 were anosmia, ageusia, and headache, but more serious complications, such as stroke, impairment of consciousness, seizures, and encephalopathy, have also been reported.

CONCLUSION

There are several similarities between neurological complications after SARS-CoV-1, MERS-CoV and COVID-19, however, the scope of the epidemics and number of patients are very different. Reports on the neurological complications after and during COVID-19 are growing on a daily basis. Accordingly, comprehensive knowledge of these complications will help health care providers to be attentive to these complications and diagnose and treat them timely.

The Potential Role of SARS-COV-2 in the Pathogenesis of Parkinson's Disease

Considering their current burden and epidemiological projections, nowadays Parkinson's disease and the COVID-19 pandemic are two key health problems. There is evidence of the pathogenic role of neurotropic viruses in neurodegenerative diseases and coronaviruses are neurotropic, with some of them selectively targeting the basal ganglia. Moreover, some authors demonstrated the longevity of these viruses in the affected cells of the nervous system for long periods. Coronavirus was detected in brain autopsies and SARS-CoV-2 has been isolated from the CSF of affected patients. The marked inflammatory response in some particular patients with COVID-19 with a consequent increase of pro-inflammatory cytokines is considered a prognostic factor. Immunologic changes are observed in patients with Parkinson's disease, possibly having a role in its pathogenesis. A dynamic pro-inflammatory state accompanies α-synuclein accumulation and the development and progression of neurodegeneration. Also, some viral infectious diseases might have a role as triggers, generating a cross autoimmune reaction against α-synuclein. In the past Coronaviruses have been related to Parkinson's disease, however, until now the causal role of these viruses is unknown. In this paper, our focus is to assess the potential relationship between SARS-CoV-2 infection and Parkinson's disease.

Neurological Damage by Coronaviruses: A Catastrophe in the Queue!

Neurological disorders caused by neuroviral infections are an obvious pathogenic manifestation. However, non-neurotropic viruses or peripheral viral infections pose a considerable challenge as their neuropathological manifestations do not emerge because of primary infection. Their secondary or bystander pathologies develop much later, like a syndrome, during and after the recovery of patients from the primary disease. Massive inflammation caused by peripheral viral infections can trigger multiple neurological anomalies. These neurological damages may range from a general cognitive and motor dysfunction up to a wide spectrum of CNS anomalies, such as Acute Necrotizing Hemorrhagic Encephalopathy, Guillain-Barré syndrome, Encephalitis, Meningitis, anxiety, and other audio-visual disabilities. Peripheral viruses like Measles virus, Enteroviruses, Influenza viruses (HIN1 series), SARS-CoV-1, MERS-CoV, and, recently, SARS-CoV-2 are reported to cause various neurological manifestations in patients and are proven to be neuropathogenic even in cellular and animal model systems. This review presents a comprehensive picture of CNS susceptibilities toward these peripheral viral infections and explains some common underlying themes of their neuropathology in the human brain.

Infections or Sepsis Preceding Clinically Diagnosed α-Synucleinopathies: A Case-Control Study

BACKGROUND

Several studies have proposed a role for infections to induce an inflammatory response triggering Parkinson's disease. This remains controversial and the influence of severe infections on other α-synucleinopathies (Dementia with Lewy Bodies, Parkinson's disease dementia, and Multiple System Atrophy) has not been adequately investigated.

OBJECTIVES

To assess the association between hospitalization-required infections or sepsis and risk of clinically diagnosed α-synucleinopathies.

METHODS

Using the medical records-linkage system (Rochester Epidemiology Project), we identified all α-synucleinopathy cases of in Olmsted County (1991-2010). Cases were matched by symptom-onset age and sex to controls. We reviewed complete medical records to detect hospital-required infections or sepsis preceding clinical-motor onset of α-synucleinopathies. We used conditional logistic regression to calculate the odds ratio of all α-synucleinopathies, adjusting for medications, coffee, and smoking.

RESULTS

There was no association between infection-related hospitalization (odds ratio: 1.05; 95% confidence interval: 0.78-1.40; P = 0.76) or sepsis (odds ratio: 0.86; 95% confidence interval: 0.40-1.85; P = 0.70) and all α-synucleinopathies in multivariable analyses. We did not identify any associations after stratifying for type of α-synucleinopathy, sex, and age at clinical-motor onset. We analyzed sepsis separately with similar results.

CONCLUSION

We did not observe any associations between infections leading to hospitalization or sepsis and development of any α-synucleinopathies. © 2020 International Parkinson and Movement Disorder Society.

Gut metagenomics-derived genes as potential biomarkers of Parkinson’s disease

Identification of the gut microbiome compositions associated with disease has become a research focus worldwide. Emerging evidence has revealed the presence of gut microbiota dysbiosis in Parkinson’s disease. In this study, we aimed to identify the gut microbiome associated with Parkinson’s disease and subsequently to screen and to validate potential diagnostic biomarkers of Parkinson’s disease. This case-control study investigated gut microbial genes in faeces from 40 volunteer Chinese patients with Parkinson’s disease and their healthy spouses using shotgun metagenomic sequencing. Furthermore, the identified specific gut microbial gene markers were validated with real-time PCR in an independent Chinese cohort of 78 Parkinson’s disease patients, 75 control subjects, 40 patients with multiple system atrophy and 25 patients with Alzheimer’s disease. We developed the first gut microbial gene catalogue associated with Parkinson’s disease. Twenty-five gene markers were identified that distinguished Parkinson’s disease patients from healthy control subjects, achieving an area under the receiver operating characteristic curve (AUC) of 0.896 (95% confidence interval: 83.1–96.1%). A highly accurate Parkinson’s disease index, which was not influenced by disease severity or Parkinson’s disease medications, was created. Testing these gene markers using quantitative PCR distinguished Parkinson’s disease patients from healthy controls not only in the 40 couples (AUC = 0.922, 95% confidence interval: 86.4–98.0%), but also in an independent group of 78 patients with Parkinson’s disease and 75 healthy control subjects (AUC = 0.905, 95% confidence interval: 86.0–95.1%). This classifier also performed a differential diagnosis power in discriminating these 78 patients with Parkinson’s disease from a cohort of 40 patients with multiple system atrophy and 25 patients with Alzheimer’s disease based on the panel of 25 biomarkers. Based on our results, the identified Parkinson’s disease index based on the gene set from the gut microbiome may be a potential diagnostic biomarker of Parkinson’s disease.

COVID-19 and possible links with Parkinson's disease and parkinsonism: from bench to bedside

This Viewpoint discusses insights from basic science and clinical perspectives on coronavirus disease 2019 (COVID-19)/severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection in the brain, with a particular focus on Parkinson's disease. Major points include that neuropathology studies have not answered the central issue of whether the virus enters central nervous system neurons, astrocytes or microglia, and the brain vascular cell types that express virus have not yet been identified. Currently, there is no clear evidence for human neuronal or astrocyte expression of angiotensin-converting enzyme 2 (ACE2), the major receptor for viral entry, but ACE2 expression may be activated by inflammation, and a comparison of healthy and infected brains is important. In contrast to the 1918 influenza pandemic and avian flu, reports of encephalopathy in COVID-19 have been slow to emerge, and there are so far no documented reports of parkinsonism apart from a single case report. We recommend consensus guidelines for the clinical treatment of Parkinson's patients with COVID-19. While a role for the virus in causing or exacerbating Parkinson's disease appears unlikely at this time, aggravation of specific motor and non-motor symptoms has been reported, and it will be important to monitor subjects after recovery, particularly for those with persisting hyposmia.

Review of Hereditary and Acquired Rare Choreas

Background:

Movement disorders are often a prominent part of the phenotype of many neurologic rare diseases. In order to promote awareness and diagnosis of these rare diseases, the International Parkinson’s and Movement Disorders Society Rare Movement Disorders Study Group provides updates on rare movement disorders.

Methods:

In this narrative review, we discuss the differential diagnosis of the rare disorders that can cause chorea.

Results:

Although the most common causes of chorea are hereditary, it is critical to identify acquired or symptomatic choreas since these are potentially treatable conditions. Disorders of metabolism and mitochondrial cytopathies can also be associated with chorea.

Discussion:

The present review discusses clues to the diagnosis of chorea of various etiologies. Authors propose algorithms to help the clinician in the diagnosis of these rare disorders.

COVID-19 Infection and Neurological Complications: Present Findings and Future Predictions

The present outbreak caused by SARS-CoV-2, an influenza virus with neurotropic potential, presents with neurological manifestations in a large proportion of the affected individuals. Disorders of the central and peripheral nervous system are all present, while stroke, ataxia, seizures, and depressed level of consciousness are more common in severely affected patients. People with these severe complications are most likely elderly with medical comorbidities, especially hypertension and other vascular risk factors. However, postinfectious complications are also expected. Neurological disorders as sequelae of influenza viruses have been repeatedly documented in the past and include symptoms, signs, and diseases occurring during the acute phase and, not rarely, during follow-up. Postinfectious neurological complications are the result of the activation of immune mechanisms and can explain the insurgence of immune-mediated diseases, including the Guillain-Barré syndrome and other diseases of the central and peripheral nervous system that in the past occurred as complications of viral infections and occasionally with vaccines. For these reasons, the present outbreak calls for the introduction of surveillance systems to monitor changes in the frequency of several immune-mediated neurological diseases. These changes will determine a reorganization of the measures apt to describe the interaction between the virus, the environment, and the host in areas of different dimensions, from local communities to regions with several millions of inhabitants. The public health system, mainly primary care, needs to be strengthened to ensure that research and development efforts are directed toward right needs and directions. To cope with the present pandemic, better collaboration is required between international organizations along with more research funding, and tools in order to detect, treat, and prevent future epidemics.

Antecedent presentation of neurological phenotypes in the Collaborative Cross reveals four classes with complex sex-dependencies

Antecedent viral infection may contribute to increased susceptibility to several neurological diseases, such as multiple sclerosis and Parkinson’s disease. Variation in clinical presentations of these diseases is often associated with gender, genetic background, or a combination of these and other factors. The complicated etiologies of these virally influenced diseases are difficult to study in conventional laboratory mouse models, which display a very limited number of phenotypes. We have used the genetically and phenotypically diverse Collaborative Cross mouse panel to examine complex neurological phenotypes after viral infection. Female and male mice from 18 CC strains were evaluated using a multifaceted phenotyping pipeline to define their unique disease profiles following infection with Theiler’s Murine Encephalomyelitis Virus, a neurotropic virus. We identified 4 distinct disease progression profiles based on limb-specific paresis and paralysis, tremors and seizures, and other clinical signs, along with separate gait profiles. We found that mice of the same strain had more similar profiles compared to those of different strains, and also identified strains and phenotypic parameters in which sex played a significant role in profile differences. These results demonstrate the value of using CC mice for studying complex disease subtypes influenced by sex and genetic background. Our findings will be useful for developing novel mouse models of virally induced neurological diseases with heterogenous presentation, an important step for designing personalized, precise treatments.

Case Report: Dengue Virus-Triggered Parkinsonism in an Adolescent

Dengue fever continues to be an important cause of morbidity and mortality in tropical and subtropical countries. A wide range of neurological manifestations including dengue encephalopathy, Guillain-Barre syndrome, acute disseminated encephalomyelitis, transverse myelitis, cranial nerve palsies, and myositis have been reported following dengue infection. But parkinsonism secondary to dengue virus infection is uncommon, with only three published case reports in adults and one in children. We describe a 13-year-old pre-morbidly normal boy, who presented with bradykinesia, bradyphonia, mask-like facies, and cogwheel rigidity while recovering from uncomplicated DF. He responded favorably to levodopa/carbidopa supplementation and had resolution of symptoms over the next 2 weeks. We also did a comparative review of all published cases of dengue-induced parkinsonism. Post-dengue, parkinsonism is uncommon, and treating clinicians should be aware of this uncommon but treatable neurological complication of a common arboviral infection.

The Parkinson's disease-associated kinase LRRK2 regulates genes required for cell adhesion, polarization, and chemotaxis in activated murine macrophages

Leucine-rich repeat kinase 2 (LRRK2) encodes a complex protein that includes kinase and GTPase domains. Genome-wide association studies have identified dominant LRRK2 alleles that predispose their carriers to late-onset idiotypic Parkinson's disease (PD) and also to autoimmune disorders such as Crohn's disease. Considerable evidence indicates that PD initiation and progression involve activation of innate immune functions in microglia, which are brain-resident macrophages. Here we asked whether LRRK2 modifies inflammatory signaling and how this modification might contribute to PD and Crohn's disease. We used RNA-Seq-based high-resolution transcriptomics to compare gene expression in activated primary macrophages derived from WT and Lrrk2 knockout mice. Remarkably, expression of a single gene, Rap guanine nucleotide exchange factor 3 (Rapgef3), was strongly up-regulated in the absence of LRRK2 and down-regulated in its presence. We observed similar regulation of Rapgef3 expression in cells treated with a highly specific inhibitor of LRRK2 protein kinase activity. Rapgef3 encodes an exchange protein, activated by cAMP 1 (EPAC-1), a guanine nucleotide exchange factor that activates the small GTPase Rap-1. Rap-1 mediates cell adhesion, polarization, and directional motility, and our results indicate that LRRK2 modulates chemotaxis of microglia and macrophages. Dominant PD-associated LRRK2 alleles may suppress EPAC-1 activity, further restricting motility and preventing efficient migration of microglia to sites of neuronal damage. Functional analysis in vivo in a subclinical infection model also indicated that Lrrk2 subtly modifies the inflammatory response. These results indicate that LRRK2 modulates the expression of genes involved in murine immune cell chemotaxis.

Parkinson's Disease: A Comprehensive Analysis of Fungi and Bacteria in Brain Tissue

Parkinson's disease (PD) is characterized by motor disorders and the destruction of dopaminergic neurons in the substantia nigra pars compacta. In addition to motor disability, many patients with PD present a spectrum of clinical symptoms, including cognitive decline, psychiatric alterations, loss of smell and bladder dysfunction, among others. Neuroinflammation is one of the most salient features of PD, but the nature of the trigger remains unknown. A plausible mechanism to explain inflammation and the range of clinical symptoms in these patients is the presence of systemic microbial infection. Accordingly, the present study provides extensive evidence for the existence of mixed microbial infections in the central nervous system (CNS) of patients with PD. Assessment of CNS sections by immunohistochemistry using specific antibodies revealed the presence of both fungi and bacteria. Moreover, different regions of the CNS were positive for a variety of microbial morphologies, suggesting infection by a number of microorganisms. Identification of specific fungal and bacterial species in different CNS regions from six PD patients was accomplished using nested PCR analysis and next-generation sequencing, providing compelling evidence of polymicrobial infections in the CNS of PD. Most of the fungal species identified belong to the genera Botrytis, Candida, Fusarium and Malassezia. Some relevant bacterial genera were Streptococcus and Pseudomonas, with most bacterial species belonging to the phyla Actinobacteria and Proteobacteria. Interestingly, we noted similarities and differences between the microbiota present in the CNS of patients with PD and that in other neurodegenerative diseases. Overall, our observations lend strong support to the concept that mixed microbial infections contribute to or are a risk factor for the neuropathology of PD. Importantly, these results provide the basis for effective treatments of this disease using already approved and safe antimicrobial therapeutics.

Immunopathology in the brain of mice following vertical transmission of Coxsackievirus B4

Coxsackie B viruses (CV-B) are associated with several central nervous system (CNS) disorders. These viruses are predominantly transmitted by fecal-oral route but vertical transmission can also occur. This work attempted to study the immune response ensuing vertical transmission of CV-B to the brain, and its eventual implementation in the brain pathogenesis. To this end, pregnant Swiss albino mice were inoculated with CV-B4 E2 or with sterile medium for control animals. At different ages after birth, brains were collected and analyzed for virus infection, histopathological changes and immune response. Infectious particles were detected in offspring's brain which demonstrates vertical transmission of the virus. This infection is persistent since the long lasting detection of viral RNA in offspring's brain. Some pathological signs including meningitis, edema and accumulation of inflammatory cells within and surrounding the inflammatory areas were observed. Immunoflorescence staining unveiled the presence of T lymphocytes and microgliosis in the sites of lesion for a long period after birth. Multiplex cytokines measurement upon supernatants of in vitro mixed brain cells and extracted mononuclear cells from offspring's brain has demonstrated an elevated secretion of the pro-inflammatory cytokines TNFα, IL-6 and IFNα and the chemokines RANTES and MCP-1. Hence, vertical transmission of CV-B4 and its persistence within offspring's brain can lead to pathological features linked to increased and sustained immune response.

Parkinsonism as a Third Wave of the COVID-19 Pandemic?

Since the initial reports of COVID-19 in December 2019, the world has been gripped by the disastrous acute respiratory disease caused by the SARS-CoV-2 virus. There are an ever-increasing number of reports of neurological symptoms in patients, from severe (encephalitis), to mild (hyposmia), suggesting the potential for neurotropism of SARS-CoV-2. This Perspective investigates the hypothesis that the reliance on self-reporting of hyposmia has resulted in an underestimation of neurological symptoms in COVID-19 patients. While the acute effect of the virus on the nervous system function is vastly overshadowed by the respiratory effects, we propose that it will be important to monitor convalescent individuals for potential long-term implications that may include neurodegenerative sequelae such as viral-associated parkinsonism. As it is possible to identify premorbid harbingers of Parkinson's disease, we propose long-term screening of SARS-CoV-2 cases post-recovery for these expressions of neurodegenerative disease. An accurate understanding of the incidence of neurological complications in COVID-19 requires long-term monitoring for sequelae after remission and a strategized health policy to ensure healthcare systems all over the world are prepared for a third wave of the virus in the form of parkinsonism.

Transient parkinsonism associated with acute Legionnaires’ disease

A 44-year-old right-handed man with a 5-day history of non-productive cough associated with subjective fevers/chills and night sweats presented to the emergency department with slurred speech. Radiography and urine antigen testing confirmed the diagnosis of Legionella pneumonia. The hospital course was complicated by acute hypoxic respiratory failure that required 7 days of invasive mechanical ventilation. Following extubation, the patient had dysarthria and developed new parkinsonism features. Brain imaging revealed a non-specific focal lesion in the left frontal lobe of unclear significance. Ciprofloxacin was decided as the final antibiotic of choice for its favourable central nervous system profile. Levodopa–carbidopa was initiated to help activate the basal ganglia. The patient had complete resolution of pneumonia and transient parkinsonism. He was able to regain most of his baseline functional status with intensive rehabilitation.

Antiviral Therapy in Patients With Chronic Hepatitis C Is Associated With a Reduced Risk of Parkinsonism

BACKGROUND

The risk of parkinsonism after antiviral treatment against chronic hepatitis C (CHC) is unclear.

OBJECTIVES

To investigate the association between CHC and parkinsonism and the efficacy of antiviral therapy.

METHODS

Using the National Health Insurance Research Database of Taiwan from 2004 to 2012, patients with and without CHC, patients receiving pegylated interferon-based antiviral therapy, and those without such therapy were matched by age, gender, and comorbidities by propensity scores and followed for new diagnoses of parkinsonism and Parkinson's disease (PD). Multivariable Cox proportional hazards regression analyses were performed.

RESULTS

Overall, 49,342 patients with CHC were matched with 49,342 non-CHC patients. After adjustment for confounding factors, there was a significantly increased risk (31%) of parkinsonism (hazard ratio [HR] 1.306; 95% confidence interval [CI], 1.208-1.412) in those with CHC and the risk of parkinsonism requiring anti-Parkinson medication (HR 1.323; 95% CI, 1.214-1.441). Furthermore, 23,647 untreated CHC patients were matched with 23,647 patients receiving antiviral therapy. Patients receiving antiviral therapy had a significantly lower risk of developing parkinsonism (38%; HR 0.618; 95% CI, 0.498-0.765) and a reduced risk of parkinsonism requiring anti-Parkinson medication (HR 0.651; 95% CI, 0.515-0.823). In sensitivity analyses, antiviral therapy significantly reduced the risk of parkinsonism and PD after adjustment for detection, selection, disease latency biases, and competing mortality. Our results suggest successful antiviral therapy associates with a reduced risk of hepatitis C virus-related parkinsonism compared with those with treatment failure.

CONCLUSIONS

CHC infection is associated with an increased risk of parkinsonism or PD. Antiviral therapy against CHC is associated with a reduced risk of parkinsonism or PD. © 2019 International Parkinson and Movement Disorder Society.

Secondary parkinsonism due to drugs, vascular lesions, tumors, trauma, and other insults

In addition to neurodegenerative disorders, there are many secondary forms of parkinsonism. The most common cause for secondary parkinsonism is the intake of distinct drugs. Neuroleptics and calcium channel blockers have been mainly described to induce parkinsonism, but also other drugs were suspected to cause or worsen parkinsonism. Another common cause for secondary parkinsonism are vascular lesions (i.e. vascular parkinsonism). Furthermore, also brain tumors have been described as rare causes for parkinsonism. Moreover, parkinsonism can be caused by chronic traumatic encephalopathy, which is a special case, since secondary insults to the brain leads to the occurrence of a neuropathologically defined disease. Other rare causes for secondary parkinsonism are lesions caused by infectious or immunological diseases as well as toxins or street drugs.

Catalpol Exerts a Neuroprotective Effect in the MPTP Mouse Model of Parkinson's Disease

The degeneration of dopaminergic (DA) neurons in Parkinson’s disease (PD) is related to inflammation and oxidative stress. Anti-inflammatory agents could reduce the risk or slow the progression of PD. Catalpol, an iridoid glycoside extracted from the roots of Rehmannia radix, has been reported to reduce the release of inflammatory factors and exert neuroprotective effects. 1-methyl-4-phenyl-1,2,3, 6-tetrahydropyridine (MPTP)-treated mice were used as the PD model and the roles of catalpol on DA neurons and its potential mechanism were investigated in this study. We found that catalpol administration mitigated the loss of DA neurons induced by MPTP and increased exploratory behavior along with tyrosine hydroxylase (TH) expression, which was accompanied by astrocyte and microglia activation. Importantly, catalpol administration significantly inhibited MPTP-triggered oxidative stress, restored growth-associated protein 43 (GAP43) and vascular endothelial growth factor (VEGF) levels. Further, we found that catalpol suppressed the activation of MKK4/JNK/c-Jun signaling, and reduced the pro-inflammatory factors and inflammasome in the mouse model of PD. Our results suggest that catalpol relieves MPTP-triggered oxidative stress, which may benefit to avoid the occurrence of chronic inflammatory reaction. Catalpol alleviates MPTP-triggered oxidative stress and thereby prevents neurodegenerative diseases-related inflammatory reaction, highlighting its therapeutic potential for the management of PD symptoms.

Infection with mosquito-borne alphavirus induces selective loss of dopaminergic neurons, neuroinflammation and widespread protein aggregation

Neuroinvasive infections with mosquito-borne alphaviruses such as Western equine encephalitis virus (WEEV) can cause post-encephalitic parkinsonism. To understand the mechanisms underlying these neurological effects, we examined the capacity of WEEV to induce progressive neurodegeneration in outbred CD-1 mice following non-lethal encephalitic infection. Animals were experientally infected with recombinant WEEV expressing firefly luciferase or dsRed (RFP) reporters and the extent of viral replication was controlled using passive immunotherapy. WEEV spread along the neuronal axis from the olfactory bulb to the entorhinal cortex, hippocampus and basal midbrain by 4 days post infection (DPI). Infection caused activation of microglia and astrocytes, selective loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and neurobehavioral abnormalities. After 8 weeks, surviving mice displayed continued loss of dopamine neurons in the SNpc, lingering glial cell activation and gene expression profiles consistent with a neurodegenerative phenotype. Strikingly, prominent proteinase K-resistant protein aggregates were present in the the entorhinal cortex, hippocampus and basal midbrain that stained positively for phospho-serine129 α-synuclein (SNCA). These results indicate that WEEV may cause lasting neurological deficits through a severe neuroinflammatory response promoting both neuronal injury and protein aggregation in surviving individuals.

Herpes simplex virus-1 (HSV-1) infection induces a potent but ineffective IFN-λ production in immune cells of AD and PD patients

Background

The sequential activation of immediate early (IE), early (E) and late (L) genes is required to allow productive herpes simplex virus type 1 (HSV-1) infection. Several evidences suggest that, together with inflammation, an immunological response incapable to counteract HSV-1 reactivation plays a role in the pathogenesis of Alzheimer’s (AD) and Parkinson’s (PD) diseases. IFN-lambda (IFN-λ), a cytokine endowed with a robust antiviral activity, contains HSV-1 reactivation. HSV-1-induced IFN-λ, IL-10 and IL-1β as well as the expression of viral IE, E and L genes were analyzed in vitro in peripheral blood mononuclear cells (PBMC) of AD and PD patients as well as of healthy controls (HC).

Methods

PBMC of AD, PD and HC were in vitro infected with one multiplicity of infection (1 MOI) HSV-1. IE, E, and L viral genes transcription as well as IFN-λ, IL-10 and IL-1β production were analyzed.

Results

In HSV-1-infected cells of AD and PD patients compared to HC: (1) transcription of IE (ICP0, ICP27) genes was reduced whereas that of E (UL41, UL29) and L (UL48, LAT) genes was increased; (2) IFN-λ mRNA expression was increased. IL-1β was augmented and IL-10 was reduced in unstimulated cells of AD and PD compared to HC; HSV-1 infection significantly increased IL-10 production in HC alone.

Conclusions

Data herein show that a proinflammatory condition is present in AD and PD, in whom attempts to obstacle viral replication via an initial, possibly more potent IFN-λ-mediated control of IE viral genes is unsuccessful.

Zika Virus and Other Emerging Arboviral Central Nervous System Infections

PURPOSE OF REVIEW

In recent years, we have observed the emergence and reemergence of a number of arthropod-borne viruses (arboviruses). Zika virus is the most recent addition to this group, first causing sporadic cases of uncomplicated febrile illness followed by sizeable outbreaks in the Pacific. However, the epidemiology and clinical features of Zika virus infection have changed rapidly and dramatically; it is now recognized as causing Guillain-Barré syndrome (GBS) in children and adults and congenital abnormalities in infected fetuses. This article reviews the epidemiology, clinical features, and diagnosis of Zika virus-associated neurologic illness and briefly reviews features of West Nile virus and Japanese encephalitis virus.

RECENT FINDINGS

Zika virus has emerged as a significant human pathogen in recent years. In 2015, it began to cause large outbreaks of febrile rash illness in South America and the Caribbean. During these large Zika virus outbreaks, a significant increase in the incidence of GBS was also observed in multiple countries/territories. Zika virus-associated GBS has several unique features, including a relatively short interval between febrile illness and GBS onset, an unusually high incidence among older people, and prominent cranial nerve abnormalities. Congenital Zika syndrome includes a myriad of abnormalities, including microcephaly, lissencephaly, hydrocephalus, arthrogryposis, and parenchymal calcifications. Currently, no treatment has been identified for Zika virus, although work on vaccines is under way.

SUMMARY

Arboviruses continue to surprise us with unexpected emergence in various locations, the nature of clinical illness, and outcomes. Zika virus presents a classic example of this type of emergence. Ongoing surveillance will be needed to evaluate the long-term pattern of Zika virus and related arboviruses.

Can infections trigger alpha-synucleinopathies?

As synucleinopathies, Parkinson's disease (PD) and multiple system atrophy (MSA) are neurodegenerative diseases that involve the spread of pathogenic alpha-synuclein (αSyn) throughout the brain. Recent studies have suggested a role for αSyn as an antimicrobial peptide in response to PD- and MSA-related infections of peripheral tissues, including those in the respiratory, gastrointestinal, and urogenital systems. In this chapter, we examine epidemiological and experimental evidence for a role of peripheral microbial infections in triggering alpha-synucleinopathies. We propose a model of how infectious triggers, in conjunction with inflammatory, environmental, and genetic facilitators, may result in transfer of pathogenic αSyn strains from the periphery to the brain, where they propagate and spread. Finally, we discuss future research challenges and programs necessary to clarify the role of infections as triggers of PD and MSA and, ultimately, to prevent the onset of these diseases by infectious triggers.

Infectious Etiologies of Parkinsonism: Pathomechanisms and Clinical Implications

Extensive research in recent decades has expanded our insights into the pathogenesis of Parkinson's disease (PD), though the underlying cause remains incompletely understood. Neuroinflammation have become a point of interest in the interconnecting areas of neurodegeneration and infectious diseases. The hypothesis concerning an infectious origin in PD stems from the observation of Parkinson-like symptoms in individuals infected with the influenza virus who then developed encephalitis lethargica. The implications of infectious pathogens have later been studied in neuronal pathways leading to the development of Parkinsonism and PD, through both a direct association and through synergistic effects of infectious pathogens in inducing neuroinflammation. This review explores the relationship between important infectious pathogens and Parkinsonism, including symptoms of Parkinsonism following infectious etiologies, infectious contributions to neuroinflammation and neurodegenerative processes associated with Parkinsonism, and the epidemiologic correlations between infectious pathogens and idiopathic PD.

Parkin Impairs Antiviral Immunity by Suppressing the Mitochondrial Reactive Oxygen Species-Nlrp3 Axis and Antiviral Inflammation

Although mitochondria are known to be involved in host defense against viral infection, the physiological role of mitophagy, a crucial mechanism for maintaining mitochondrial homeostasis, in antiviral immunity remains poorly defined. Here, we show that Parkin, a central player in mitophagy, has a vital function in regulating host antiviral responses. Parkin-knockout mice exhibit improved viral clearance and survival after viral infection. However, Parkin deficiency does not affect antiviral signaling and interferon production. Instead, Parkin deficiency augments innate antiviral inflammation by enhancing mitochondrial ROS (mtROS)-mediated NLRP3 inflammasome activation and promoting viral clearance. Loss of NLRP3 can reverse the enhanced antiviral responses in Parkin knockout mice. Furthermore, we find that Parkin expression is downregulated in peripheral blood mononuclear cells of patients infected with virus. Collectively, our results suggest that Parkin plays an important role in antiviral immunity by controlling mtROS-NLRP3 axis-mediated inflammation. These findings provide physiological insight of the importance of mitophagy in regulating host antiviral response.

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Loss of Parkin enhances viral clearance but does not affect type I IFN production

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Parkin deletion promotes antiviral inflammation in vivo

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Parkin deficiency enhances antiviral inflammation via the mtROS-NLRP3 axis

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The expression of Parkin is downregulated following viral infection

The Gut and Parkinson's Disease-A Bidirectional Pathway

Humans evolved a symbiotic relationship with their gut microbiome, a complex microbial community composed of bacteria, archaea, protists, and viruses, including bacteriophages. The enteric nervous system (ENS) is a gateway for the bidirectional communication between the brain and the gut, mostly through the vagus nerve (VN). Environmental exposure plays a pivotal role in both the composition and functionality of the gut microbiome and may contribute to susceptibility to neurodegenerative disorders, such as Parkinson's disease (PD). The neuropathological hallmark of PD is the widespread appearance of alpha-synuclein aggregates in both the central and peripheral nervous systems, including the ENS. Many studies suggest that gut toxins can induce the formation of α-syn aggregates in the ENS, which may then be transmitted in a prion-like manner to the CNS through the VN. PD is strongly associated with aging and its negative effects on homeostatic mechanisms protecting from inflammation, oxidative stress, and protein malfunction. In this mini-review, we revisit some landmark discoveries in the field of Parkinson's research and focus on the gut-brain axis. In the process, we highlight evidence showing gut-associated dysbiosis and related microbial-derived components as important players and risk factors for PD. Therefore, the gut microbiome emerges as a potential target for protective measures aiming to prevent PD onset.

Transient splenial lesion due to non-cirrhotic hyperammonaemia in dengue fever

Transient splenial lesion(TSL) is seen in a variety of conditions and is detectable only on MRI of the brain. Dengue fever (DF) is a common viral infection encountered in the tropics. The affected patients may face neurological complications like encephalopathy and intracranial haemorrhage, or even ischaemic stroke. Non-cirrhotic hyperammonaemia is a rare scenario; and its occurrence in DF is unknown. The patient being described had DF and developed dysarthria. His MRI brain showed splenial hyperintensity. Further evaluation revealed non-cirrhotic hyperammonaemia. To the best of our knowledge, TSL due to non-cirrhotic hyperammonaemia in DF is an unreported scenario.

The viral protein corona directs viral pathogenesis and amyloid aggregation

Artificial nanoparticles accumulate a protein corona layer in biological fluids, which significantly influences their bioactivity. As nanosized obligate intracellular parasites, viruses share many biophysical properties with artificial nanoparticles in extracellular environments and here we show that respiratory syncytial virus (RSV) and herpes simplex virus type 1 (HSV-1) accumulate a rich and distinctive protein corona in different biological fluids. Moreover, we show that corona pre-coating differentially affects viral infectivity and immune cell activation. In addition, we demonstrate that viruses bind amyloidogenic peptides in their corona and catalyze amyloid formation via surface-assisted heterogeneous nucleation. Importantly, we show that HSV-1 catalyzes the aggregation of the amyloid β-peptide (Aβ42), a major constituent of amyloid plaques in Alzheimer's disease, in vitro and in animal models. Our results highlight the viral protein corona as an acquired structural layer that is critical for viral-host interactions and illustrate a mechanistic convergence between viral and amyloid pathologies.

Mitochondrial Protein PINK1 Positively Regulates RLR Signaling

The serine/threonine kinase phosphatase and tensin homolog (PTEN)-induced putative kinase 1(PINK1) controls mitochondrial quality and plays a vital role in the pathogenesis of early-onset Parkinson's disease. However, whether PINK1 has functions in innate antiviral immunity is largely unknown. Here, we report that viral infection down regulates PINK1 expression in macrophages. PINK1 knockdown results in decreased cytokine production and attenuated IRF3 and NF-κB activation upon viral infection. PINK1 promotes the retinoic-acid-inducible gene I (RIG-I)-like receptors (RLR)-triggered immune responses in a kinase domain-dependent manner. Furthermore, PINK1 associates with TRAF3 via the kinase domain and inhibits Parkin-mediated TRAF3 K48-linked proteasomal degradation. In addition, PINK1 interacts with Yes-associated protein 1 (YAP1) upon viral infection and impairs YAP1/IRF3 complex formation. Collectively, our results demonstrate that PINK1 positively regulates RIG-I triggered innate immune responses by inhibiting TRAF3 degradation and relieving YAP-mediated inhibition of the cellular antiviral response.

Th17 cells: a promising therapeutic target for Parkinson's disease?

INTRODUCTION

Parkinson's disease (PD) is the most common neurodegenerative movement disorder caused by the progressive loss of neurons in the midbrain and other brain regions. Only symptomatic treatment is currently available. Mounting evidence suggests that T cells are a key contributor to PD pathogenesis and neurodegeneration by a mechanism that requires further elucidation. Areas covered: We discuss the evidence of imbalanced activation of effector T cell populations in PD and summarize the data of Th17 involvement and Th17-regulated mechanisms in PD pathology. Moreover, possible Th17-related molecular targets as possible neuroprotective immunomodulatory therapeutic targets for PD are examined. Expert Opinion: Existing data show that Th17 cells, their effector molecules, and signaling pathways are potentially effective therapeutic targets for neuroprotective immunomodulation in PD treatment. However, specificity of action within Th17-mediated signaling pathways for PD requires careful consideration.

Impact of infection on risk of Parkinson's disease: a quantitative assessment of case-control and cohort studies

Identifying modifiable risk factors for Parkinson's disease (PD) to help prevent this disease has attracted increasing interest in recent years for the limited effective drugs at present. Despite many studies indicated that infection acts as a risk factor for PD, there is no quantitative assessment of the impact of viral and bacterial infections on the risk of developing PD. The present study performed a meta-analysis on the basis of 38 datasets from 13 studies covering 287,773 PD cases and 7,102,901 controls to ascertain the association between PD and infection and the differences in the strength of the viral and bacterial infections. The overall meta-analytic results indicated that individuals with infection had a 20% increased risk of PD compared with controls (OR 1.20, 95%CI 1.07-1.32). The subgroup analysis according to the type of infection found that bacterial infection had a significant impact on increased risk of PD (OR 1.40, 95%CI 1.32-1.48). The present analysis indicated that infection could increase the risk of developing PD, and physician should be aware of the risk of developing PD in subjects with infection.

HIV-1-Associated Neurocognitive Disorders: Is HLA-C Binding Stability to β2-Microglobulin a Missing Piece of the Pathogenetic Puzzle?

AIDS dementia complex (ADC) and HIV-associated neurocognitive disorders (HAND) are complications of HIV-1 infection. Viral infections are risk factors for the development of neurodegenerative disorders. Aging is associated with low-grade inflammation in the brain, i.e., the inflammaging. The molecular mechanisms linking immunosenescence, inflammaging and the pathogenesis of neurodegenerative disorders, such as Alzheimer's disease (AD) and Parkinson's disease, are largely unknown. ADC and HAND share some pathological features with AD and may offer some hints on the relationship between viral infections, neuroinflammation, and neurodegeneration. β2-microglobulin (β2m) is an important pro-aging factor that interferes with neurogenesis and worsens cognitive functions. Several studies published in the 80-90s reported high levels of β2m in the cerebrospinal fluid of patients with ADC. High levels of β2m have also been detected in AD. Inflammatory diseases in elderly people are associated with polymorphisms of the MHC-I locus encoding HLA molecules that, by associating with β2m, contribute to cellular immunity. We recently reported that HLA-C, no longer associated with β2m, is incorporated into HIV-1 virions, determining an increase in viral infectivity. We also documented the presence of HLA-C variants more or less stably linked to β2m. These observations led us to hypothesize that some variants of HLA-C, in the presence of viral infections, could determine a greater release and accumulation of β2m, which in turn, may be involved in triggering and/or sustaining neuroinflammation. ADC is the most severe form of HAND. To explore the role of HLA-C in ADC pathogenesis, we analyzed the frequency of HLA-C variants with unstable binding to β2m in a group of patients with ADC. We found a higher frequency of unstable HLA-C alleles in ADC patients, and none of them was harboring stable HLA-C alleles in homozygosis. Our data suggest that the role of HLA-C variants in ADC/HAND pathogenesis deserves further studies. If confirmed in a larger number of samples, this finding may have practical implication for a personalized medicine approach and for developing new therapies to prevent HAND. The exploration of HLA-C variants as risk factors for AD and other neurodegenerative disorders may be a promising field of study.

Immunology of West Nile Virus Infection and the Role of Alpha-Synuclein as a Viral Restriction Factor

West Nile virus (WNV) is a single-stranded RNA flavivirus and is a major cause of viral encephalitis worldwide. Experimental models of WNV infection in mice are commonly used to define acute neuroinflammatory responses in the brain. Alpha-synuclein (Asyn) is a protein of primarily neuronal origin and is a major cause of Parkinson's disease (PD), a disorder characterized by loss of dopaminergic neurons. Both WNV and PD pathologies are largely mediated by inflammation of the central nervous system (neuroinflammation) and have overlapping inflammatory pathways. In this review, we highlight the roles of the immune system in both diseases while comparing and contrasting both protective and pathogenic roles of immune cells and their effector proteins. Additionally, we review the current literature showing that Asyn is an important mediator of the immune response with diverging roles in PD (pathogenic) and WNV disease (neuroprotective).

A 14-Year-Old Boy With Fevers, Cytopenias, and Neurocognitive Decline

A 14-year-old boy presented to our institution with a 1-month history of neurocognitive decline and intermittent fevers. His history was significant for fevers, headaches, and a 10-lb weight loss. Previous examinations by multiple medical providers were significant only for bilateral cervical lymphadenopathy. Previous laboratory workup revealed leukopenia, neutropenia, and elevated inflammatory markers. Despite improvement in his laboratory values after his initial presentation, his fevers persisted, and he developed slowed and "jerky" movements, increased sleep, slurred speech, delusions, visual hallucinations, and deterioration in his school performance. A brain MRI performed at an outside hospital before admission at our institution was concerning for patchy, increased T2 and fluid-attenuated inversion recovery signal intensity in multiple areas, including the basal ganglia. After transfer to our institution and admission to the pediatric hospital medicine team, the patient had an acute decompensation. Our subspecialists will discuss the initial evaluation, workup, differential diagnosis, definitive diagnosis, and subsequent management of this patient.

Persistent EcoHIV infection induces nigral degeneration in 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-intoxicated mice

The widespread use of antiretroviral therapy for treatment of human immunodeficiency virus (HIV) infections has dramatically improved the quality and duration of life for HIV-positive individuals. Despite this success, HIV persists for the life of an infected person in tissue reservoirs including the nervous system. Thus, whether HIV exacerbates age-related brain disorders such as Parkinson's disease (PD) is of concern. In support of this idea, HIV infection can be associated with motor and gait abnormalities that parallel late-stage manifestations of PD including dopaminergic neuronal loss. With these findings in hand, we investigated whether viral infection could affect nigrostriatal degeneration or exacerbate chemically induced nigral degeneration. We now demonstrate an additive effect of EcoHIV on dopaminergic neuronal loss and neuroinflammation induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine intoxication. HIV-1-infected humanized mice failed to recapitulate these EcoHIV results suggesting species-specific neural signaling. The results demonstrate a previously undefined EcoHIV-associated neurodegenerative response that may be used to model pathobiological aspects of PD.