[Ocular manifestations of viral diseases]

Varicella-zoster virus-related neurological complications: From infection to immunomodulatory therapies

The Varicella-zoster virus (VZV), classified as a neurotropic member of the Herpesviridae family, exhibits a characteristic pathogenicity, predominantly inducing varicella, commonly known as chickenpox, during the initial infectious phase, and triggering the reactivation of herpes zoster, more commonly recognized as shingles, following its emergence from a latent state. The pathogenesis of VZV-associated neuroinflammation involves a complex interplay between viral replication within sensory ganglia and immune-mediated responses that contribute to tissue damage and dysfunction. Upon primary infection, VZV gains access to sensory ganglia, establishing latent infection within neurons. During reactivation, the virus can spread along sensory nerves, triggering a cascade of inflammatory mediators, chemokines, and immune cell infiltration in the affected neural tissues. The role of both adaptive and innate immune reactions, including the contributions of T and B cells, macrophages, and dendritic cells, in orchestrating the immune-mediated damage in the central nervous system is elucidated. Furthermore, the aberrant activation of the natural defence mechanism, characterised by the dysregulated production of immunomodulatory proteins and chemokines, has been implicated in the pathogenesis of VZV-induced neurological disorders, such as encephalitis, myelitis, and vasculopathy. The intricate balance between protective and detrimental immune responses in the context of VZV infection emphasises the necessity for an exhaustive comprehension of the immunopathogenic mechanisms propelling neuroinflammatory processes. Despite the availability of vaccines and antiviral therapies, VZV-related neurological complications remain a significant concern, particularly in immunocompromised individuals and the elderly. Elucidating these mechanisms might facilitate the emergence of innovative immunomodulatory strategies and targeted therapies aimed at mitigating VZV-induced neuroinflammatory damage and improving clinical outcomes. This comprehensive understanding enhances our grasp of viral pathogenesis and holds promise for pioneering therapeutic strategies designed to mitigate the neurological ramifications of VZV infections.

ICP4-Associated Activation of Rap1b Facilitates Herpes Simplex Virus Type I (HSV-1) Infection in Human Corneal Epithelial Cells

The strong contribution of RAS-related protein 1b (Rap1b) to cytoskeleton remodeling determines intracellular and extracellular physiological activities, including the successful infection of viruses in permissive cells, but its role in the HSV-1 life cycle is still unclear. Here, we demonstrated that the HSV-1 immediate early (IE) gene ICP4 inhibits protein kinase A (PKA) phosphorylation to induce Rap1b-activation-mediated viral infection. Rap1b activation and membrane enrichment begin at the early stage of HSV-1 infection and remain active during the proliferation period of the virus. Treating the cells with Rap1b small interfering RNA (siRNA) showed a dose-dependent decrease in viral infection levels, but no dose-dependent increase was observed after Rap1b overexpression. Further investigation indicated that the suppression of Rap1b activation derives from phosphorylated PKA and Rap1b mutants with partial or complete prenylation instead of phosphorylation, which promoted viral infection in a dose-dependent manner. Furthermore, the PKA agonist Forskolin disturbed Rap1b activation in a dose-dependent manner, accompanied by a decreasing trend in viral infection. Moreover, the HSV-1 IE gene ICP4 induced PKA dephosphorylation, leading to continuous Rap1b activation, followed by cytoskeleton rearrangement induced by cell division control protein 42 (CDC42) and Ras-related C3 botulinum toxin substrate 1 (RAC1). These further stimulated membrane-triggered physiological processes favoring virus infection. Altogether, we show the significance of Rap1b during HSV-1 infection and uncover the viral infection mechanism determined by the posttranslational regulation of the viral ICP4 gene and Rap1b host protein.

The roles of autophagy and mitophagy in corneal pathology: current knowledge and future perspectives

The cornea is the clear dome that covers the front portion of the globe. The primary functions of the cornea are to promote the refraction of light and to protect the eye from invading pathogens, both of which are essential for the preservation of vision. Homeostasis of each cellular layer of the cornea requires the orchestration of multiple processes, including the ability to respond to stress. One mechanism whereby cells respond to stress is autophagy, or the process of "self-eating." Autophagy functions to clear damaged proteins and organelles. During nutrient deprivation, amino acids released from protein breakdown via autophagy are used as a fuel source. Mitophagy, a selective form of autophagy, functions to clear damaged mitochondria. Thus, autophagy and mitophagy are important intracellular degradative processes that sustain tissue homeostasis. Importantly, the inhibition or excessive activation of these processes result in deleterious effects on the cell. In the eye, impairment or inhibition of these mechanisms have been associated with corneal disease, degenerations, and dystrophies. This review summarizes the current body of knowledge on autophagy and mitophagy at all layers in the cornea in both non-infectious and infectious corneal disease, dystrophies, and degenerations. It further highlights the critical gaps in our understanding of mitochondrial dysfunction, with implications for novel therapeutics in clinical practice.

Ocular manifestations of COVID-19

COVID-19 is a disease caused by a SARS-CoV-2 viral infection, a disease that was first detected in December 2019 in Wuhan, Hubei Province, China. COVID-19, formerly known as 2019 Novel Coronavirus (2019-nCoV) respiratory disease, was officially named COVID-19 by the World Health Organization (WHO) in February 2020. By 25 May 2021, there were 33,579,116 confirmed cases with 599,109 COVID-19 deaths worldwide. The purpose of this review article is to provide an update on what is currently known about COVID-19 ocular symptoms in adults, the elderly, and children in the literature. Finally, this article will review the eye protection precautions that should be implemented in our clinics. To assess the current literature, PubMed was searched from December 2019 to 25 May 2021. Randomized trials, observational studies, case series or case reports, letters of research, and letters to editors were selected for confirmed cases of COVID-19. According to current scientific literature since the outbreak in December 2019, 205 articles have been published. Conjunctivitis, conjunctival hyperemia, and chemosis have been reported in adults with COVID-19. There have been few studies on children and elderly patients, and further research in these age groups is needed. Finally, wearing eye protection when seeing patients on a daily basis during the pandemic is essential.

Post COVID-19 Complications, Adjunct Therapy Explored, And Steroidal After Effects

For survivors of the COVID-19 disease, defeating the virus is just the beginning of a long road to recovery. The virus’s inducibility and catastrophic effects are distributed in multiple organs. The induction of cytokine storms in COVID-19 patients is due to the interaction of the SARS-CoV-2 virus and the host receptor, leading to various immunopathological consequences that might eventually lead to death. So far, it has hit tons of people across the world, but there is still no effective treatment. Patients facing the complications of COVID-19 after recovering have shown extensive clinical symptoms similar to previously circulating coronaviruses. Previous knowledge, and literature have opened up ways to treat this disease and manage post-COVID-19 complications, which poses a severe challenge to health system globally and may exacerbate the fragmentation of diseases. The use of steroids, as a treatment, showed various health problems and side-effects in COVID-19 patients. This review substantially discusses various post-COVID-19 complications observed, adjunctive therapies used along with common COVID-19treatment and spotlighted their side effects and consequences. This review provides latest literature on COVID-19 which emphasizes the subsequent complications in various organs, side-effects of drug, and alternative regimes that were used to treat COVID-19.