Mitochondrial Dysfunction: A Prelude to Neuropathogenesis of SARS-CoV-2

Focusing on mitochondria in the brain: from biology to therapeutics

Mitochondria have multiple functions such as supplying energy, regulating the redox status, and producing proteins encoded by an independent genome. They are closely related to the physiology and pathology of many organs and tissues, among which the brain is particularly prominent. The brain demands 20% of the resting metabolic rate and holds highly active mitochondrial activities. Considerable research shows that mitochondria are closely related to brain function, while mitochondrial defects induce or exacerbate pathology in the brain. In this review, we provide comprehensive research advances of mitochondrial biology involved in brain functions, as well as the mitochondria-dependent cellular events in brain physiology and pathology. Furthermore, various perspectives are explored to better identify the mitochondrial roles in neurological diseases and the neurophenotypes of mitochondrial diseases. Finally, mitochondrial therapies are discussed. Mitochondrial-targeting therapeutics are showing great potentials in the treatment of brain diseases.

Precision nutrition to reset virus-induced human metabolic reprogramming and dysregulation (HMRD) in long-COVID

SARS-CoV-2, the etiological agent of COVID-19, is devoid of any metabolic capacity; therefore, it is critical for the viral pathogen to hijack host cellular metabolic machinery for its replication and propagation. This single-stranded RNA virus with a 29.9 kb genome encodes 14 open reading frames (ORFs) and initiates a plethora of virus-host protein-protein interactions in the human body. These extensive viral protein interactions with host-specific cellular targets could trigger severe human metabolic reprogramming/dysregulation (HMRD), a rewiring of sugar-, amino acid-, lipid-, and nucleotide-metabolism(s), as well as altered or impaired bioenergetics, immune dysfunction, and redox imbalance in the body. In the infectious process, the viral pathogen hijacks two major human receptors, angiotensin-converting enzyme (ACE)-2 and/or neuropilin (NRP)-1, for initial adhesion to cell surface; then utilizes two major host proteases, TMPRSS2 and/or furin, to gain cellular entry; and finally employs an endosomal enzyme, cathepsin L (CTSL) for fusogenic release of its viral genome. The virus-induced HMRD results in 5 possible infectious outcomes: asymptomatic, mild, moderate, severe to fatal episodes; while the symptomatic acute COVID-19 condition could manifest into 3 clinical phases: (i) hypoxia and hypoxemia (Warburg effect), (ii) hyperferritinemia ('cytokine storm'), and (iii) thrombocytosis (coagulopathy). The mean incubation period for COVID-19 onset was estimated to be 5.1 days, and most cases develop symptoms after 14 days. The mean viral clearance times were 24, 30, and 39 days for acute, severe, and ICU-admitted COVID-19 patients, respectively. However, about 25-70% of virus-free COVID-19 survivors continue to sustain virus-induced HMRD and exhibit a wide range of symptoms that are persistent, exacerbated, or new 'onset' clinical incidents, collectively termed as post-acute sequelae of COVID-19 (PASC) or long COVID. PASC patients experience several debilitating clinical condition(s) with >200 different and overlapping symptoms that may last for weeks to months. Chronic PASC is a cumulative outcome of at least 10 different HMRD-related pathophysiological mechanisms involving both virus-derived virulence factors and a multitude of innate host responses. Based on HMRD and virus-free clinical impairments of different human organs/systems, PASC patients can be categorized into 4 different clusters or sub-phenotypes: sub-phenotype-1 (33.8%) with cardiac and renal manifestations; sub-phenotype-2 (32.8%) with respiratory, sleep and anxiety disorders; sub-phenotype-3 (23.4%) with skeleto-muscular and nervous disorders; and sub-phenotype-4 (10.1%) with digestive and pulmonary dysfunctions. This narrative review elucidates the effects of viral hijack on host cellular machinery during SARS-CoV-2 infection, ensuing detrimental effect(s) of virus-induced HMRD on human metabolism, consequential symptomatic clinical implications, and damage to multiple organ systems; as well as chronic pathophysiological sequelae in virus-free PASC patients. We have also provided a few evidence-based, human randomized controlled trial (RCT)-tested, precision nutrients to reset HMRD for health recovery of PASC patients.

The effects of urolithin A on poly I:C-induced microglial activation

Neuroinflammation can be triggered by various stimuli, including viral infections. Viruses can directly invade the brain and infect neuronal cells or indirectly trigger a "cytokine storm" in the periphery that eventually leads to microglial activation in the brain. While this initial activation of microglial cells is important for viral clearance, chronic activation leads to excessive inflammation and oxidative stress, which can be neurotoxic. Remarkebly, recent studies have shown that certain viruses such as influenza A virus, coronavirus, herpes virus and Epstein-Barr virus may be involved in the development of neurodegenerative diseases such as Parkinson's disease, Alzheimer's disease, and multiple sclerosis. Therefore, it is important to find therapeutic strategies against chronic neuroinflammation triggered by viral infections. Here, we investigated the effects of urolithin A (UA) on microglial activation in vitro induced by a viral mimetic, poly I:C, in a triple co-culture system of neurons, astrocytes and microglial cells. Immunocytochemistry was used to perform a comprehensive single-cell analysis of the morphological changes of microglia as an indicator of their reactive state. Treatment with UA significantly prevented the poly I:C-induced reactive state of microglia, which was characterized by increased expression of the microglial activation markers CD68 and IBA-1. UA restored the poly I:C-induced morphology by restoring microglial ramification. In addition, UA was able to reduce the release of the pro-inflammatory mediators CCL2, TNF-α, and IL-1β and showed a trend toward attenuation of cellular ROS production in poly I:C-treated cultures. Overall, this study suggests that UA as a component of a healthy diet may help prevent virus-induced neuroinflammation and may have therapeutic potential for future studies to prevent or treat neurodegenerative diseases by targeting the associated neuroinflammatory processes.

Investigating the Potential Shared Molecular Mechanisms between COVID-19 and Alzheimer's Disease via Transcriptomic Analysis

SARS-CoV-2 caused the COVID-19 pandemic. COVID-19 may elevate the risk of cognitive impairment and even cause dementia in infected individuals; it may accelerate cognitive decline in elderly patients with dementia, possibly in Alzheimer's disease (AD) patients. However, the mechanisms underlying the interplay between AD and COVID-19 are still unclear. To investigate the underlying mechanisms and associations between AD progression and SARS-CoV-2 infection, we conducted a series of bioinformatics research into SARS-CoV-2-infected cells, COVID-19 patients, AD patients, and SARS-CoV-2-infected AD patients. We identified the common differentially expressed genes (DEGs) in COVID-19 patients, AD patients, and SARS-CoV-2-infected cells, and these DEGs are enriched in certain pathways, such as immune responses and cytokine storms. We constructed the gene interaction network with the signaling transduction module in the center and identified IRF7, STAT1, STAT2, and OAS1 as the hub genes. We also checked the correlations between several key transcription factors and the SARS-CoV-2 and COVID-19 pathway-related genes. We observed that ACE2 expression is positively correlated with IRF7 expression in AD and coronavirus infections, and interestingly, IRF7 is significantly upregulated in response to different RNA virus infections. Further snRNA-seq analysis indicates that NRGN neurons or endothelial cells may be responsible for the increase in ACE2 and IRF7 expression after SARS-CoV-2 infection. The positive correlation between ACE2 and IRF7 expressions is confirmed in the hippocampal formation (HF) of SARS-CoV-2-infected AD patients. Our findings could contribute to the investigation of the molecular mechanisms underlying the interplay between AD and COVID-19 and to the development of effective therapeutic strategies for AD patients with COVID-19.

Human-derived air-liquid interface cultures decipher Alzheimer's disease-SARS-CoV-2 crosstalk in the olfactory mucosa

BACKGROUND

The neurological effects of the coronavirus disease of 2019 (COVID-19) raise concerns about potential long-term consequences, such as an increased risk of Alzheimer's disease (AD). Neuroinflammation and other AD-associated pathologies are also suggested to increase the risk of serious SARS-CoV-2 infection. Anosmia is a common neurological symptom reported in COVID-19 and in early AD. The olfactory mucosa (OM) is important for the perception of smell and a proposed site of viral entry to the brain. However, little is known about SARS-CoV-2 infection at the OM of individuals with AD.

METHODS

To address this gap, we established a 3D in vitro model of the OM from primary cells derived from cognitively healthy and AD individuals. We cultured the cells at the air-liquid interface (ALI) to study SARS-CoV-2 infection under controlled experimental conditions. Primary OM cells in ALI expressed angiotensin-converting enzyme 2 (ACE-2), neuropilin-1 (NRP-1), and several other known SARS-CoV-2 receptor and were highly vulnerable to infection. Infection was determined by secreted viral RNA content and confirmed with SARS-CoV-2 nucleocapsid protein (NP) in the infected cells by immunocytochemistry. Differential responses of healthy and AD individuals-derived OM cells to SARS-CoV-2 were determined by RNA sequencing.

RESULTS

Results indicate that cells derived from cognitively healthy donors and individuals with AD do not differ in susceptibility to infection with the wild-type SARS-CoV-2 virus. However, transcriptomic signatures in cells from individuals with AD are highly distinct. Specifically, the cells from AD patients that were infected with the virus showed increased levels of oxidative stress, desensitized inflammation and immune responses, and alterations to genes associated with olfaction. These results imply that individuals with AD may be at a greater risk of experiencing severe outcomes from the infection, potentially driven by pre-existing neuroinflammation.

CONCLUSIONS

The study sheds light on the interplay between AD pathology and SARS-CoV-2 infection. Altered transcriptomic signatures in AD cells may contribute to unique symptoms and a more severe disease course, with a notable involvement of neuroinflammation. Furthermore, the research emphasizes the need for targeted interventions to enhance outcomes for AD patients with viral infection. The study is crucial to better comprehend the relationship between AD, COVID-19, and anosmia. It highlights the importance of ongoing research to develop more effective treatments for those at high risk of severe SARS-CoV-2 infection.

The Ways of the Virus: Interactions of Platelets and Red Blood Cells with SARS-CoV-2, and Their Potential Pathophysiological Significance in COVID-19

The hematological effects of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are important in COVID-19 pathophysiology. However, the interactions of SARS-CoV-2 with platelets and red blood cells are still poorly understood. There are conflicting data regarding the mechanisms and significance of these interactions. The aim of this review is to put together available data and discuss hypotheses, the known and suspected effects of the virus on these blood cells, their pathophysiological and diagnostic significance, and the potential role of platelets and red blood cells in the virus's transport, propagation, and clearance by the immune system. We pay particular attention to the mutual activation of platelets, the immune system, the endothelium, and blood coagulation and how this changes with the evolution of SARS-CoV-2. There is now convincing evidence that platelets, along with platelet and erythroid precursors (but not mature erythrocytes), are frequently infected by SARS-CoV-2 and functionally changed. The mechanisms of infection of these cells and their role are not yet entirely clear. Still, the changes in platelets and red blood cells in COVID-19 are significantly associated with disease severity and are likely to have prognostic and pathophysiological significance in the development of thrombotic and pulmonary complications.

Mitochondrial Dysfunction and Apoptosis in Brain Microvascular Endothelial Cells Following Blast Traumatic Brain Injury

Blood brain barrier (BBB) breakdown is a key driver of traumatic brain injury (TBI), contributing to prolonged neurological deficits and increased risk of death in TBI patients. Strikingly, the role of endothelium in the progression of BBB breakdown has not been sufficiently investigated, even though it constitutes the bulk of BBB structure. In the current study, we investigate TBI-induced changes in the brain endothelium at the subcellular level, particularly focusing on mitochondrial dysfunction, using a combination of confocal imaging, gene expression analysis, and molecular profiling by Raman spectrometry. Herein, we developed and applied an in-vitro blast-TBI (bTBI) model that employs an acoustic shock tube to deliver injury to cultured human brain microvascular endothelial cells (HBMVEC). We found that this injury results in aberrant expression of mitochondrial genes, as well as cytokines/ inflammasomes, and regulators of apoptosis. Furthermore, injured cells exhibit a significant increase in reactive oxygen species (ROS) and in Ca2+ levels. These changes are accompanied by overall reduction of intracellular proteins levels as well as profound transformations in mitochondrial proteome and lipidome. Finally, blast injury leads to a reduction in HBMVEC cell viability, with up to 50% of cells exhibiting signs of apoptosis following 24 h after injury. These findings led us to hypothesize that mitochondrial dysfunction in HBMVEC is a key component of BBB breakdown and TBI progression.

Development of nanozymes for promising alleviation of COVID-19-associated arthritis

The COVID-19 pandemic caused by SARS-CoV-2 has been identified as a culprit in the development of a variety of disorders, including arthritis. Although the emergence of arthritis following SARS-CoV-2 infection may not be immediately discernible, its underlying pathogenesis is likely to involve a complex interplay of infections, oxidative stress, immune responses, abnormal production of inflammatory factors, cellular destruction, etc. Fortunately, recent advancements in nanozymes with enzyme-like activities have shown potent antiviral effects and the ability to inhibit oxidative stress and cytokines and provide immunotherapeutic effects while also safeguarding diverse cell populations. These adaptable nanozymes have already exhibited efficacy in treating common types of arthritis, and their distinctive synergistic therapeutic effects offer great potential in the fight against arthritis associated with COVID-19. In this comprehensive review, we explore the potential of nanozymes in alleviating arthritis following SARS-CoV-2 infection by neutralizing the underlying factors associated with the disease. We also provide a detailed analysis of the common therapeutic pathways employed by these nanozymes and offer insights into how they can be further optimized to effectively address COVID-19-associated arthritis.

Long COVID as a Tauopathy: Of "Brain Fog" and "Fusogen Storms"

Long COVID, also called post-acute sequelae of SARS-CoV-2, is characterized by a multitude of lingering symptoms, including impaired cognition, that can last for many months. This symptom, often called "brain fog", affects the life quality of numerous individuals, increasing medical complications as well as healthcare expenditures. The etiopathogenesis of SARS-CoV-2-induced cognitive deficit is unclear, but the most likely cause is chronic inflammation maintained by a viral remnant thriving in select body reservoirs. These viral sanctuaries are likely comprised of fused, senescent cells, including microglia and astrocytes, that the pathogen can convert into neurotoxic phenotypes. Moreover, as the enteric nervous system contains neurons and glia, the virus likely lingers in the gastrointestinal tract as well, accounting for the intestinal symptoms of long COVID. Fusogens are proteins that can overcome the repulsive forces between cell membranes, allowing the virus to coalesce with host cells and enter the cytoplasm. In the intracellular compartment, the pathogen hijacks the actin cytoskeleton, fusing host cells with each other and engendering pathological syncytia. Cell-cell fusion enables the virus to infect the healthy neighboring cells. We surmise that syncytia formation drives cognitive impairment by facilitating the "seeding" of hyperphosphorylated Tau, documented in COVID-19. In our previous work, we hypothesized that the SARS-CoV-2 virus induces premature endothelial senescence, increasing the permeability of the intestinal and blood-brain barrier. This enables the migration of gastrointestinal tract microbes and/or their components into the host circulation, eventually reaching the brain where they may induce cognitive dysfunction. For example, translocated lipopolysaccharides or microbial DNA can induce Tau hyperphosphorylation, likely accounting for memory problems. In this perspective article, we examine the pathogenetic mechanisms and potential biomarkers of long COVID, including microbial cell-free DNA, interleukin 22, and phosphorylated Tau, as well as the beneficial effect of transcutaneous vagal nerve stimulation.

Statin Use in Relation to COVID-19 and Other Respiratory Infections: Muscle and Other Considerations

Statins have been widely advocated for use in COVID-19 based on large favorable observational associations buttressed by theoretical expected benefits. However, past favorable associations of statins to pre-COVID-19 infection outcomes (also buttressed by theoretical benefits) were unsupported in meta-analysis of RCTs, RR = 1.00. Initial RCTs in COVID-19 appear to follow this trajectory. Healthy-user/tolerator effects and indication bias may explain these disparities. Moreover, cholesterol drops in proportion to infection severity, so less severely affected individuals may be selected for statin use, contributing to apparent favorable statin associations to outcomes. Cholesterol transports fat-soluble antioxidants and immune-protective vitamins. Statins impair mitochondrial function in those most reliant on coenzyme Q10 (a mevalonate pathway product also transported on cholesterol)-i.e., those with existing mitochondrial compromise, whom data suggest bear increased risks from both COVID-19 and from statins. Thus, statin risks of adverse outcomes are amplified in those patients at risk of poor COVID-19 outcomes-i.e., those in whom adjunctive statin therapy may most likely be given. High reported rates of rhabdomyolysis in hospitalized COVID-19 patients underscore the notion that statin-related risks as well as benefits must be considered. Advocacy for statins in COVID-19 should be suspended pending clear evidence of RCT benefits, with careful attention to risk modifiers.

Analytical Techniques for Single-Cell Biochemical Assays of Lipids

Lipids are essential cellular components forming membranes, serving as energy reserves, and acting as chemical messengers. Dysfunction in lipid metabolism and signaling is associated with a wide range of diseases including cancer and autoimmunity. Heterogeneity in cell behavior including lipid signaling is increasingly recognized as a driver of disease and drug resistance. This diversity in cellular responses as well as the roles of lipids in health and disease drive the need to quantify lipids within single cells. Single-cell lipid assays are challenging due to the small size of cells (∼1 pL) and the large numbers of lipid species present at concentrations spanning orders of magnitude. A growing number of methodologies enable assay of large numbers of lipid analytes, perform high-resolution spatial measurements, or permit highly sensitive lipid assays in single cells. Covered in this review are mass spectrometry, Raman imaging, and fluorescence-based assays including microscopy and microseparations.

Pathophysiological involvement of host mitochondria in SARS-CoV-2 infection that causes COVID-19: a comprehensive evidential insight

SARS-CoV-2 is a positive-strand RNA virus that infects humans through the nasopharyngeal and oral route causing COVID-19. Scientists left no stone unturned to explore a targetable key player in COVID-19 pathogenesis against which therapeutic interventions can be initiated. This article has attempted to review, coordinate and accumulate the most recent observations in support of the hypothesis predicting the altered state of mitochondria concerning mitochondrial redox homeostasis, inflammatory regulations, morphology, bioenergetics and antiviral signalling in SARS-CoV-2 infection. Mitochondria is extremely susceptible to physiological as well as pathological stimuli, including viral infections. Recent studies suggest that SARS-CoV-2 pathogeneses alter mitochondrial integrity, in turn mitochondria modulate cellular response against the infection. SARS-CoV-2 M protein inhibited mitochondrial antiviral signalling (MAVS) protein aggregation in turn hinders innate antiviral response. Viral open reading frames (ORFs) also play an instrumental role in altering mitochondrial regulation of immune response. Notably, ORF-9b and ORF-6 impair MAVS activation. In aged persons, the NLRP3 inflammasome is over-activated due to impaired mitochondrial function, increased mitochondrial reactive oxygen species (mtROS), and/or circulating free mitochondrial DNA, resulting in a hyper-response of classically activated macrophages. This article also tries to understand how mitochondrial fission-fusion dynamics is affected by the virus. This review comprehends the overall mitochondrial attribute in pathogenesis as well as prognosis in patients infected with COVID-19 taking into account pertinent in vitro, pre-clinical and clinical data encompassing subjects with a broad range of severity and morbidity. This endeavour may help in exploring novel non-canonical therapeutic strategies to COVID-19 disease and associated complications.

Possible Pathogenesis and Prevention of Long COVID: SARS-CoV-2-Induced Mitochondrial Disorder

Patients who have recovered from coronavirus disease 2019 (COVID-19) infection may experience chronic fatigue when exercising, despite no obvious heart or lung abnormalities. The present lack of effective treatments makes managing long COVID a major challenge. One of the underlying mechanisms of long COVID may be mitochondrial dysfunction. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections can alter the mitochondria responsible for energy production in cells. This alteration leads to mitochondrial dysfunction which, in turn, increases oxidative stress. Ultimately, this results in a loss of mitochondrial integrity and cell death. Moreover, viral proteins can bind to mitochondrial complexes, disrupting mitochondrial function and causing the immune cells to over-react. This over-reaction leads to inflammation and potentially long COVID symptoms. It is important to note that the roles of mitochondrial damage and inflammatory responses caused by SARS-CoV-2 in the development of long COVID are still being elucidated. Targeting mitochondrial function may provide promising new clinical approaches for long-COVID patients; however, further studies are needed to evaluate the safety and efficacy of such approaches.

Potential of Nano-Antioxidants and Nanomedicine for Recovery from Neurological Disorders Linked to Long COVID Syndrome

Long-term neurological complications, persisting in patients who cannot fully recover several months after severe SARS-CoV-2 coronavirus infection, are referred to as neurological sequelae of the long COVID syndrome. Among the numerous clinical post-acute COVID-19 symptoms, neurological and psychiatric manifestations comprise prolonged fatigue, "brain fog", memory deficits, headache, ageusia, anosmia, myalgias, cognitive impairments, anxiety, and depression lasting several months. Considering that neurons are highly vulnerable to inflammatory and oxidative stress damages following the overproduction of reactive oxygen species (ROS), neuroinflammation and oxidative stress have been suggested to dominate the pathophysiological mechanisms of the long COVID syndrome. It is emphasized that mitochondrial dysfunction and oxidative stress damages are crucial for the pathogenesis of neurodegenerative disorders. Importantly, antioxidant therapies have the potential to slow down and prevent disease progression. However, many antioxidant compounds display low bioavailability, instability, and transport to targeted tissues, limiting their clinical applications. Various nanocarrier types, e.g., liposomes, cubosomes, solid lipid nanoparticles, micelles, dendrimers, carbon-based nanostructures, nanoceria, and other inorganic nanoparticles, can be employed to enhance antioxidant bioavailability. Here, we highlight the potential of phytochemical antioxidants and other neuroprotective agents (curcumin, quercetin, vitamins C, E and D, melatonin, rosmarinic acid, N-acetylcysteine, and Ginkgo Biloba derivatives) in therapeutic strategies for neuroregeneration. A particular focus is given to the beneficial role of nanoparticle-mediated drug-delivery systems in addressing the challenges of antioxidants for managing and preventing neurological disorders as factors of long COVID sequelae.

Melatonin: Regulation of Viral Phase Separation and Epitranscriptomics in Post-Acute Sequelae of COVID-19

The relentless, protracted evolution of the SARS-CoV-2 virus imposes tremendous pressure on herd immunity and demands versatile adaptations by the human host genome to counter transcriptomic and epitranscriptomic alterations associated with a wide range of short- and long-term manifestations during acute infection and post-acute recovery, respectively. To promote viral replication during active infection and viral persistence, the SARS-CoV-2 envelope protein regulates host cell microenvironment including pH and ion concentrations to maintain a high oxidative environment that supports template switching, causing extensive mitochondrial damage and activation of pro-inflammatory cytokine signaling cascades. Oxidative stress and mitochondrial distress induce dynamic changes to both the host and viral RNA m6A methylome, and can trigger the derepression of long interspersed nuclear element 1 (LINE1), resulting in global hypomethylation, epigenetic changes, and genomic instability. The timely application of melatonin during early infection enhances host innate antiviral immune responses by preventing the formation of "viral factories" by nucleocapsid liquid-liquid phase separation that effectively blockades viral genome transcription and packaging, the disassembly of stress granules, and the sequestration of DEAD-box RNA helicases, including DDX3X, vital to immune signaling. Melatonin prevents membrane depolarization and protects cristae morphology to suppress glycolysis via antioxidant-dependent and -independent mechanisms. By restraining the derepression of LINE1 via multifaceted strategies, and maintaining the balance in m6A RNA modifications, melatonin could be the quintessential ancient molecule that significantly influences the outcome of the constant struggle between virus and host to gain transcriptomic and epitranscriptomic dominance over the host genome during acute infection and PASC.

Role of SARS-CoV-2 in Modifying Neurodegenerative Processes in Parkinson's Disease: A Narrative Review

The COVID-19 pandemic, caused by SARS-CoV-2, continues to impact global health regarding both morbidity and mortality. Although SARS-CoV-2 primarily causes acute respiratory distress syndrome (ARDS), the virus interacts with and influences other organs and tissues, including blood vessel endothelium, heart, gastrointestinal tract, and brain. We are learning much about the pathophysiology of SARS-CoV-2 infection; however, we are just beginning to study and understand the long-term and chronic health consequences. Since the pandemic's beginning in late 2019, older adults, those with pre-existing illnesses, or both, have an increased risk of contracting COVID-19 and developing severe COVID-19. Furthermore, older adults are also more likely to develop the neurodegenerative disorder Parkinson's disease (PD), with advanced age as the most significant risk factor. Thus, does SARS-CoV-2 potentially influence, promote, or accelerate the development of PD in older adults? Our initial focus was aimed at understanding SARS-CoV-2 pathophysiology and the connection to neurodegenerative disorders. We then completed a literature review to assess the relationship between PD and COVID-19. We described potential molecular and cellular pathways that indicate dopaminergic neurons are susceptible, both directly and indirectly, to SARS-CoV-2 infection. We concluded that under certain pathological circumstances, in vulnerable persons-with-Parkinson's disease (PwP), SARS-CoV-2 acts as a neurodegenerative enhancer to potentially support the development or progression of PD and its related motor and non-motor symptoms.