West Nile virus induces a post-infectious pro-inflammatory state that explains transformation of stable ocular myasthenia gravis to myasthenic crises

SARS-CoV-2 and the Eyes: A Review of the Literature on Transmission, Detection, and Ocular Manifestations

During the coronavirus disease 2019 (COVID-19) pandemic, numerous reports of ocular anomalies occurring in patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have emerged. The most frequently reported pathology is conjunctivitis, which may be the first or only clinical manifestation of the disease. Involvement of SARS-CoV-2 in development of alterations in other ocular structures was suggested, including the cornea, the retina, and blood vessels. Possible mechanisms include direct activity of the viral agent, as well as systemic inflammatory response with accompanying thromboembolic complications. Genetic material of SARS-CoV-2 was detected in ocular secretions of infected individuals, including asymptomatic patients. Moreover, angiotensin-converting enzyme 2 (ACE2), a receptor protein used by the virus to enter the cell, has been found on the surface of various structures of the eye, which indicates a risk of transmission through ocular tissues. Therefore, it is crucial to use eye protection by medical professionals having contact with potentially infected patients. This paper is a review of the literature regarding ocular manifestations of SARS-CoV-2 infection and a summary of the current state of knowledge about possibility of transmission from an ophthalmology point of view. For data collection, a thorough PubMed search was performed, using the key words: "COVID ocular", "COVID eye", "SARS-CoV-2 ocular", and "SARS-CoV-2 eye". Conclusions: SARS-CoV-2 infection may manifest itself in various ocular conditions. Eye protection should not be neglected, as recent studies suggest the eye as a potential route of transmission. Further search for adequate safety measures in ophthalmology practice is required.

Variations in West Nile Virus neuroinvasive infection: A case series of three patients in West Phoenix

West Nile Virus (WNV) is the most common mosquito-borne virus in the United States and North America. Although WNV disease occurs on a spectrum ranging from a relatively benign febrile illness to life-threatening neuroinvasive disease, the clinical presentations can vary widely and thus necessitates a high degree of suspicion. Here we describe three such cases where each individual presented with a unique constellation of symptoms that made the diagnosis challenging. It is essential for physicians to be well informed on the differing symptomology so early diagnosis and supportive management can mitigate poor prognosis.

The role of innate immunity in myasthenia gravis

Myasthenia gravis (MG) is a T cell-driven, B cell-mediated and autoantibody-dependent autoimmune disorder against neuromuscular junctions (NMJ). Accumulated evidence has emerged regarding the role of innate immunity in the pathogenesis of MG. In this review, we proposed two hypothesis underlying the pathological mechanism. In the context of gene predisposition, on the one hand, Toll-like receptors (TLRs) pathways were initiated by viral infection in the thymus with MG to generate chemokines and pro-inflammatory cytokines such as Type I interferon (IFN), which facilitate the thymus to function as a tertiary lymphoid organ (TLO). On the another hand, the antibodies against acetylcholine receptors (AChR) generated by thymus then activated the classical pathways on thymus and neuromuscular junction (NMJ). Futher, we also highlight the role of innate immune cells in the pathogenic response. Finally, we provide some future perspectives in developing new therapeutic approaches particularly targeting the innate immunity for MG.

Management of thymomatous myasthenia gravis - Case report of a rare Covid19 infection sequelae

Introduction

SARS CoV19 infection can predispose to many autoimmune and neurological conditions, thymomatous myasthenia gravis being one of them. The rarity of these case poses therapeutic dilemmas about their further management.

Presentation of case

A 61 year old gentleman who had covid19 infection 2 months back, presented with new onset myasthenia gravis and an anterior mediastinal mass. He was diagnosed as a case of anti acetyl choline receptor antibody positive thymomatous myasthenia gravis. The patient was posted for video assisted thoracoscopic excision of thymoma. The procedure was uneventful and patient was discharged with improvement in myasthenic symptoms. Histopathological examination confirmed the diagnosis of WHO Type A Spindle cell thymoma.

Discussion

SARS CoV19 infection is associated with an array of autoimmune disorders due to various proposed phenomenon including molecular mimicry and loss of immune tolerance. Post infectious thymomatous myasthenia gravis is extremely uncommon, and can be managed with open, minimally invasive or robotic approach.

Conclusion

This is the first documented case of post covid19 infection thymomatous myasthenia gravis to the best of our knowledge, managed with minimally invasive thoracoscopic surgery. Further research is required for documentation of the natural history of the disease and therapeutic outcomes.

The Roles of Osteopontin in the Pathogenesis of West Nile Encephalitis

Osteopontin (OPN), a multifunctional protein encoded by the secreted phosphoprotein-1 (Spp-1) gene in humans, plays important roles in a variety of physiological conditions, such as biomineralization, bone remodeling and immune functions. OPN also has significant roles in the pathogenesis of autoimmune, allergy and inflammatory diseases, as well as bacterial, fungal and viral infections. West Nile virus (WNV), a mosquito-transmitted flavivirus, is the leading agent for viral encephalitis in North America. Recent progress has been made in understanding both the biological functions of OPN and the pathogenesis of WNV. In this review article, we have summarized the current understanding of the biology of OPN and its vital roles in the pathogenesis of WNV encephalitis.

Detection of IgM and IgG Antibodies to Human Parvovirus B19 in Sera of Patients with Thymoma-Associated Myasthenia Gravis

Much uncertainty still exists about the viral etiology of myasthenia gravis (MG). To address this, we explored the relationship between human parvovirus B19 (PVB19) infection and MG by investigating the presence of PVB19-specific antibodies in serum. A total of 131 patients with MG (including 47 with thymoma-associated MG, 14 with hyperplasia-associated MG, and 70 with unknown thymic lesions) and 172 healthy volunteers were enrolled in this study. Enzyme linked immunosorbent assay was conducted to detect virus-specific antibodies in cell-free serum. The data were analyzed using Pearson chi-square (χ²) and Fisher's exact tests. In the 131 patients with MG, there was no significant difference between male (53.41 ± 14.65 years) and female (50.19 ± 15.28 years) groups regarding mean age (p > 0.05). Among all MG subgroups, the largest age group comprised participants aged 30-60 years. We found that the frequency of detecting immunoglobulin G (IgG) antibodies against PVB19 VP1 and VP2 was significantly higher among patients with MG (68.70%) than in healthy controls (41.86%) (p < 0.001). In particular, the positive rate for anti-PVB19 IgG in patients with thymoma-associated MG (35/47, 74.47%) was significantly higher than that in healthy participants (72/172, 41.86%; p < 0.001). The findings of this study indicate that PVB19 infection may play a role in the etiopathogenesis of MG, particularly in patients with thymoma-associated MG. The study protocol was registered at ClinicalTrials.gov with the identifier ChiCTR-1900023338.

New onset of ocular myasthenia gravis in a patient with COVID-19: a novel case report and literature review

The novel coronavirus outbreak of SARS-CoV-2 first began in Wuhan, China, in December 2019. The most striking manifestation of SARS-CoV-2 is atypical pneumonia and respiratory complications; however, various neurological manifestations are now well recognized. Currently, there have been very few case reports regarding COVID-19 in patients with a known history of myasthenia gravis. Myasthenia gravis (MG) causes muscle weakness, especially respiratory muscles, in high-risk COVID-19 patients, which can lead to severe respiratory compromise. There are few reported cases of severe myasthenia crisis following COVID-19, likely due to the involvement of the respiratory apparatus and the use of immunosuppressive medication. We report the first case of ocular MG developing secondary to COVID-19 infection in a 65-year-old woman. Two weeks prior to hospitalization, the patient suffered from cough, fever, and diarrhea and was found to be positive for COVID-19 via a nasopharyngeal RT-PCR swab test. The electrodiagnostic test showed decremental response over more than 10% on repetitive nerve stimulation test of orbicularis oculi. She tested positive for antibodies against acetylcholine receptor. COVID-19 is known to cause the release of inflammatory cytokines, leading to immune-mediated damage. MG is an immune-mediated disorder caused by molecular mimicry and autoantibodies against the neuromuscular junction.

Tumor Necrosis Factor-Alpha Signaling May Contribute to Chronic West Nile Virus Post-infectious Proinflammatory State

Background: West Nile virus (WNV) causes a spectrum of human disease ranging from a febrile illness (WNV fever) to severe neuroinvasive disease (meningitis, encephalitis, acute flaccid paralysis). Since WNV gained entry into North America in 1999, clinicians caring for WNV survivors have observed persistent neurological symptoms occurring long-after the production of neutralizing antibodies and clearance of the virus. Accordingly, alternative pathogeneses other than direct viral invasion have been hypothesized to explain these post-infectious symptoms. The dominant hypothesis is that antiviral inflammatory responses triggered initially to clear WNV may persist to promote a post-infectious proinflammatory state.

Methods: In 4 serologically-confirmed WNV patients with persistent post-infectious symptoms (3 WNV fever, 1 neuroinvasive disease), we ordered a comprehensive cytokine panel at weeks 8, 10, 12, and 36 months post-onset of illness, respectively, to better understand the pathophysiology of the protracted symptoms.

Results: All patients had abnormally elevated tumor necrosis factor alpha (TNF-α), a major molecule triggering antiviral cytokines and chronic inflammation in many human autoimmune diseases, but heretofore not reported to be upregulated in human WNV infection. Three patients also had elevations of other proinflammatory proteins. Major symptoms included fatigue, arthralgias, myalgias, generalized or multifocal pain or weakness, imbalance, headaches, cognitive problems, and symptoms of dysautonomia.

Conclusion: The findings provide support for an extended post-infectious proinflammatory state that may contribute to chronic inflammation and long-term morbidity in some WNV survivors and further suggest that TNF-α may play a pathogenic role in initiating this inflammatory environment. Clinical trials may be warranted to determine if TNF-α inhibitors or other immunosuppressive agents can improve patient outcomes.

Current Understanding of West Nile Virus Clinical Manifestations, Immune Responses, Neuroinvasion, and Immunotherapeutic Implications

West Nile virus (WNV) is the most common mosquito-borne virus in North America. WNV-associated neuroinvasive disease affects all ages, although elderly and immunocompromised individuals are particularly at risk. WNV neuroinvasive disease has killed over 2300 Americans since WNV entered into the United States in the New York City outbreak of 1999. Despite 20 years of intensive laboratory and clinical research, there are still no approved vaccines or antivirals available for human use. However, rapid progress has been made in both understanding the pathogenesis of WNV and treatment in clinical practices. This review summarizes our current understanding of WNV infection in terms of human clinical manifestations, host immune responses, neuroinvasion, and therapeutic interventions.

Differential Expression of Genes Related to Innate Immune Responses in Ex Vivo Spinal Cord and Cerebellar Slice Cultures Infected with West Nile Virus

West Nile virus (WNV) infection results in a spectrum of neurological symptoms, ranging from a benign fever to severe WNV neuroinvasive disease with high mortality. Many who recover from WNV neuroinvasive infection present with long-term deficits, including weakness, fatigue, and cognitive problems. While neurons are a main target of WNV, other cell types, especially astrocytes, play an important role in promoting WNV-mediated central nervous system (CNS) damage. Conversely, it has been shown that cultured primary astrocytes secrete high levels of interferons (IFNs) immediately after WNV exposure to protect neighboring astrocytes, as well as neurons. However, how intrinsic responses to WNV in specific cell types and different regions of the brain modify immune protection is not fully understood. Here, we used a mouse ex vivo spinal cord slice culture (SCSC) and cerebellar slice culture (CSC) models to determine the innate immune responses specific to the CNS during WNV infection. Slices were prepared from the spinal cord and cerebellar tissue of 7–9-day-old mouse pups. Four-day-old SCSC or CSC were infected with 1 × 10³ or 1 × 10⁵ PFU of WNV, respectively. After 12 h exposure to WNV and 3 days post-infection in normal growth media, the pooled slice cultures were processed for total RNA extraction and for gene expression patterns using mouse Affymetrix arrays. The expression patterns of a number of genes were significantly altered between the mock- and WNV-treated groups, both in the CSCs and SCSCs. However, distinct differences were observed when CSC data were compared with SCSC. CSCs showed robust induction of interferons (IFNs), IFN-stimulated genes (ISGs), and regulatory factors. Some of the antiviral genes related to IFN were upregulated more than 25-fold in CSCs as compared to mock or SCSC. Though SCSCs had twice the number of dysregulated genes, as compared CSCs, they exhibited a much subdued IFN response. In addition, SCSCs showed astrogliosis and upregulation of astrocytic marker genes. In sum, our results suggest that early anti-inflammatory response to WNV infection in CSCs may be due to large population of distinct astrocytic cell types, and lack of those specialized astrocytes in SCSC may make spinal cord cells more susceptible to WNV damage. Further, the understanding of early intrinsic immune response events in WNV-infected ex vivo culture models could help develop potential therapies against WNV.