Herpes simplex virus keratitis: an update of the pathogenesis and current treatment with oral and topical antiviral agents

Viral Keratitis, Surgical Intervention in Viral Keratitis, Challenges in Diagnosis and Treatment of Viral Keratitis, HSV, HZV

Viral keratitis is a significant cause of ocular morbidity and visual impairment worldwide. In recent years, there has been a growing understanding of the pathogenesis, clinical manifestations, and diagnostic modalities for viral keratitis. The most common viral pathogens associated with this condition are adenovirus, herpes simplex (HSV), and varicella-zoster virus (VZV). However, emerging viruses such as cytomegalovirus (CMV), Epstein-Barr virus (EBV), and Vaccinia virus can also cause keratitis. Non-surgical interventions are the mainstay of treatment for viral keratitis. Antiviral agents such as Acyclovir, Ganciclovir, and trifluridine have effectively reduced viral replication and improved clinical outcomes. Additionally, adjunctive measures such as lubrication, corticosteroids, and immunomodulatory agents have alleviated symptoms by reducing inflammation and facilitating tissue repair. Despite these conservative approaches, some cases of viral keratitis may progress to severe forms, leading to corneal scarring, thinning, or perforation. In such instances, surgical intervention becomes necessary to restore corneal integrity and visual function. This review article aims to provide an overview of the current perspectives and surgical interventions in managing viral keratitis. The choice of surgical technique depends on the extent and severity of corneal involvement. As highlighted in this article, on-going research and advancements in surgical interventions hold promise for further improving outcomes in patients with viral keratitis.

Enhancement of HSV-1 cell-free virion release by the envelope protein gC

Glycoprotein C (gC), one of ∼12 HSV-1 envelope glycoproteins, carries out several important functions during infection, including the enhancement of virion attachment by binding to host cell heparan sulfate proteoglycans (HSPG). Here we report that gC can also enhance the release of cell-free progeny virions at the end of the infectious cycle. This activity was observed in multiple cellular contexts including Vero cells and immortalized human keratinocytes. In the absence of gC, progeny virions bound more tightly to infected cells, suggesting that gC promotes the detachment of virions from the infected cell surface. Given this finding, we analyzed the biochemical interactions that tether progeny virions to cells and report evidence for two distinct modes of binding. One is consistent with a direct interaction between gC and HSPG, whereas the other is gC-independent and likely does not involve HSPG. Together, our results i) identify a novel function for a long-studied HSV-1 glycoprotein, and ii) demonstrate that the extracellular release of HSV-1 virions is a dynamic process involving multiple viral and host components.

T Cell Surveillance during Cutaneous Viral Infections

The skin is a complex tissue that provides a strong physical barrier against invading pathogens. Despite this, many viruses can access the skin and successfully replicate in either the epidermal keratinocytes or dermal immune cells. In this review, we provide an overview of the antiviral T cell biology responding to cutaneous viral infections and how these responses differ depending on the cellular targets of infection. Much of our mechanistic understanding of T cell surveillance of cutaneous infection has been gained from murine models of poxvirus and herpesvirus infection. However, we also discuss other viral infections, including flaviviruses and papillomaviruses, in which the cutaneous T cell response has been less extensively studied. In addition to the mechanisms of successful T cell control of cutaneous viral infection, we highlight knowledge gaps and future directions with possible impact on human health.

Immunopathology of herpes simplex virus-associated neuroinflammation: Unveiling the mysteries

The immunopathology of herpes simplex virus (HSV)-associated neuroinflammation is a captivating and intricate field of study within the scientific community. HSV, renowned for its latent infection capability, gives rise to a spectrum of neurological expressions, ranging from mild symptoms to severe encephalitis. The enigmatic interplay between the virus and the host's immune responses profoundly shapes the outcome of these infections. This review delves into the multifaceted immune reactions triggered by HSV within neural tissues, intricately encompassing the interplay between innate and adaptive immunity. Furthermore, this analysis delves into the delicate equilibrium between immune defence and the potential for immunopathology-induced neural damage. It meticulously dissects the roles of diverse immune cells, cytokines, and chemokines, unravelling the intricacies of neuroinflammation modulation and its subsequent effects. By exploring HSV's immune manipulation and exploitation mechanisms, this review endeavours to unveil the enigmas surrounding the immunopathology of HSV-associated neuroinflammation. This comprehensive understanding enhances our grasp of viral pathogenesis and holds promise for pioneering therapeutic strategies designed to mitigate the neurological ramifications of HSV infections.

Corneal ring infiltrate- far more than Acanthamoeba keratitis: review of pathophysiology, morphology, differential diagnosis and management

OBJECTIVE

Ring infiltrates usually accompany numerous infectious and sterile ocular disorders. Nevertheless, systemic conditions, drugs toxicity and contact lens wear may present with corneal ring infiltrate in substantial part. Considering its detrimental effect on vision, detailed knowledge on etiology, pathophysiology, differential diagnosis, and management should be considered essential for every ophthalmologist.

METHODS

The PUBMED database was searched for "corneal ring infiltrate" and "ring infiltrate" phrases, "sterile corneal infiltrate" and "corneal infiltrate". We analyzed articles written in English on risk factors, pathophysiology, clinical manifestation, morphological features, ancillary tests (anterior-segment optical coherence tomography, corneal scraping, in vivo confocal microscopy), differential diagnosis and management of corneal ring infiltrate.

RESULTS

Available literature depicts multifactorial origin of corneal ring infiltrate. Dual immunological pathophysiology, involving both antibodies-dependent and -independent complement activation, is underlined. Furthermore, we found that the worldwide most prevalent among non-infectious and infectious ring infiltrates are ring infiltrates related to contact-lens wear and bacterial keratitis respectively. Despite low incidence of Acanthamoeba keratitis, it manifests with corneal ring infiltrate with the highest proportion of the affected patients (one third). However, similar ring infiltrate might appear as a first sign of general diseases manifestation and require targeted treatment. Every corneal ring infiltrate with compromised epithelium should be scraped and treat as an infectious infiltrate until not proven otherwise. Of note, microbiological ulcer might also lead to immunological ring and therefore require anti-inflammatory treatment.

CONCLUSION

Corneal ring infiltrate might be triggered not only by ocular infectious and non-infectious factors, but also by systemic conditions. Clinical assessment is crucial for empirical diagnosis. Furthermore, treatment is targeted towards the underlying condition but should begin with anti-infectious regimen until not proven otherwise.

Cell Intrinsic Determinants of Alpha Herpesvirus Latency and Pathogenesis in the Nervous System

Alpha herpesvirus infections (α-HVs) are widespread, affecting more than 70% of the adult human population. Typically, the infections start in the mucosal epithelia, from which the viral particles invade the axons of the peripheral nervous system. In the nuclei of the peripheral ganglia, α-HVs establish a lifelong latency and eventually undergo multiple reactivation cycles. Upon reactivation, viral progeny can move into the nerves, back out toward the periphery where they entered the organism, or they can move toward the central nervous system (CNS). This latency-reactivation cycle is remarkably well controlled by the intricate actions of the intrinsic and innate immune responses of the host, and finely counteracted by the viral proteins in an effort to co-exist in the population. If this yin-yang- or Nash-equilibrium-like balance state is broken due to immune suppression or genetic mutations in the host response factors particularly in the CNS, or the presence of other pathogenic stimuli, α-HV reactivations might lead to life-threatening pathologies. In this review, we will summarize the molecular virus-host interactions starting from mucosal epithelia infections leading to the establishment of latency in the PNS and to possible CNS invasion by α-HVs, highlighting the pathologies associated with uncontrolled virus replication in the NS.

Current clinical applications of anterior segment optical coherence tomography angiography: a review

Optical coherence tomography (OCT) is a revolutionary in vivo imaging technology that presents real-time information on ocular structures. Angiography based on OCT, known as optical coherence tomography angiography (OCTA), is a noninvasive and time-saving technique originally utilized for visualizing retinal vasculature. As devices and built-in systems have evolved, high-resolution images with depth-resolved analysis have assisted ophthalmologists in accurately localizing pathology and monitoring disease progression. With the aforementioned advantages, application of OCTA has extended from the posterior to anterior segment. This nascent adaptation showed good delineation of the vasculature in the cornea, conjunctiva, sclera, and iris. Thus, neovascularization of the avascular cornea and hyperemia or ischemic changes involving the conjunctiva, sclera, and iris has become prospective applications for AS-OCTA. Although traditional dye-based angiography is regarded as the gold standard in demonstrating vasculature in the anterior segment, AS-OCTA is expected to be a comparable but more patient-friendly alternative. In its initial stage, AS-OCTA has exhibited great potential in pathology diagnosis, therapeutic evaluation, presurgical planning, and prognosis assessments in anterior segment disorders. In this review of AS-OCTA, we aim to summarize scanning protocols, relevant parameters, and clinical applications as well as limitations and future directions. We are sanguine about its wide application in the future with the development of technology and refinement in built-in systems.

Role of IL-27 in HSV-1-Induced Herpetic Stromal Keratitis

Herpetic stromal keratitis (HSK) is a painful and vision-impairing disease caused by recurrent HSV-1 infection of the cornea. The virus replication in the corneal epithelium and associated inflammation play a dominant role in HSK progression. Current HSK treatments targeting inflammation or virus replication are partially effective and promote HSV-1 latency, and long-term use can cause side effects. Thus, understanding molecular and cellular events that control HSV-1 replication and inflammation is crucial for developing novel HSK therapies. In this study, we report that ocular HSV-1 infection induces the expression of IL-27, a pleiotropic immunoregulatory cytokine. Our data indicate that HSV-1 infection stimulates IL-27 production by macrophages. Using a primary corneal HSV-1 infection mouse model and IL-27 receptor knockout mice, we show that IL-27 plays a critical role in controlling HSV-1 shedding from the cornea, the optimum induction of effector CD4+ T cell responses, and limiting HSK progression. Using in vitro bone marrow-derived macrophages, we show that IL-27 plays an antiviral role by regulating macrophage-mediated HSV-1 killing, IFN-β production, and IFN-stimulated gene expression after HSV-1 infection. Furthermore, we report that IL-27 is critical for macrophage survival, Ag uptake, and the expression of costimulatory molecules involved in the optimum induction of effector T cell responses. Our results indicate that IL-27 promotes endogenous antiviral and anti-inflammatory responses and represents a promising target for suppressing HSK progression.

Herpes Simplex Virus-1 ICP27 Nuclear Export Signal Mutants Exhibit Cell Type-Dependent Deficits in Replication and ICP4 Expression

Herpes simplex virus type-1 (HSV-1) protein ICP27 is an essential immediate early (IE) protein that promotes the expression of viral early (E) and late (L) genes via multiple mechanisms. Our understanding of this complex regulatory protein has been greatly enhanced by the characterization of HSV-1 mutants bearing engineered alterations in the ICP27 gene. However, much of this analysis has been performed in interferon-deficient Vero monkey cells. Here, we assessed the replication of a panel of ICP27 mutants in several other cell types. Our analysis shows that mutants lacking ICP27's amino (N)-terminal nuclear export signal (NES) display a striking cell type-dependent growth phenotype, i.e., they grow semi-permissively in Vero and some other cells but are tightly blocked for replication in primary human fibroblasts and multiple human cell lines. This tight growth defect correlates with a failure of these mutants to replicate viral DNA. We also report that HSV-1 NES mutants are deficient in expressing the IE protein ICP4 at early times postinfection. Analysis of viral RNA levels suggests that this phenotype is due, at least in part, to a defect in the export of ICP4 mRNA to the cytoplasm. In combination, our results (i) show that ICP27's NES is critically important for HSV-1 replication in many human cells, and (ii) suggest that ICP27 plays a heretofore unappreciated role in the expression of ICP4. IMPORTANCE HSV-1 IE proteins drive productive HSV-1 replication. The major paradigm of IE gene induction, developed over many years, involves the parallel activation of the five IE genes by the viral tegument protein VP16, which recruits the host RNA polymerase II (RNAP II) to the IE gene promoters. Here, we provide evidence that ICP27 can enhance ICP4 expression early in infection. Because ICP4 is required for transcription of viral E and L genes, this finding may be relevant to understanding how HSV-1 enters and exits the latent state in neurons.

Can the triumph of mRNA vaccines against COVID-19 be extended to other viral infections of humans and domesticated animals?

The unprecedented success of mRNA vaccines in managing the COVID-19 pandemic raises the prospect of applying the mRNA platform to other viral diseases of humans and domesticated animals, which may lead to more efficacious vaccines for some agents. We briefly discuss reasons why mRNA vaccines achieved such success against COVID-19 and indicate what other virus infections and disease conditions might also be ripe for control using mRNA vaccines. We also evaluate situations where mRNA could prove valuable to rebalance the status of immune responsiveness and achieve success as a therapeutic vaccine approach against infections that induce immunoinflammatory lesions.

Effectiveness of Commonly Used Contact Lens Disinfectants Against SARS-CoV-2

OBJECTIVE

To assess the effect of commonly used contact lens disinfectants against severe acute respiratory syndrome corona virus 2 (SARS-CoV-2).

METHODS

The efficacy of five disinfectant solutions against SARS-CoV-2 was tested in the presence and absence of contact lenses (CLs). Three types of unused CLs (hard gas permeable, soft hydrogel, and soft silicone hydrogel) and worn silicone hydrogel CLs were tested. Contact lenses were infected with SARS-CoV-2 and disinfected at various times, with and without rubbing and rinsing, as per manufacturer's instructions. Reverse-transcriptase polymerase chain reaction (RT-PCR) and viability polymerase chain reaction (PCR) were applied to detect SARS-CoV-2 RNA and viral infectivity of SARS-CoV-2, respectively.

RESULTS

In the presence of SARS-CoV-2-infected CLs, no SARS-CoV-2 RNA could be detected when disinfectant solutions were used according to the manufacturer's instructions. When SARS-Co-V2-infected CLs were disinfected without the rub-and-rinse step, SARS-CoV-2 RNA was detected at almost each time interval with each disinfecting solution tested for both new and worn CLs. In the absence of CLs, viable SARS-CoV-2 was detected with all disinfectant solutions except Menicon Progent at all time points.

CONCLUSIONS

Disinfectant solutions effectively disinfect CLs from SARS-CoV-2 if manufacturer's instructions are followed. The rub-and-rinse regimen is mainly responsible for disinfection. The viability PCR may be useful to indicate potential infectiousness.

Ophthalmic Solutions with a Broad Antiviral Action: Evaluation of Their Potential against Ocular Herpetic Infections

HSV-1 can be associated with severe and recurrent eye infections characterized by a strong inflammatory response that leads to blepharoconjunctivitis, epithelial and stromal keratitis, and retinal necrosis. The incidence of HSV-1 keratitis is 1.5 million every year worldwide, including more than 40,000 new cases exhibiting serious visual failures. Generally, the therapy uses antiviral drugs to promote healing; however, there are currently no compounds that are able to completely eradicate the virus. In addition, the phenomenon of resistance is rapidly spreading among HSV-1 strains, creating mutants developing resistance to the common antiviral drugs; therefore, deep research on this issue is warranted. The efficacy of different ophthalmic solutions already on the market was evaluated for reducing HSV-1 infection. Different plaque assays were set up on epithelial cells, revealing that two ophthalmic solutions were able to inhibit viral replication in the early stages of infection. The data were further confirmed by molecular tests analyzing the expression levels of the principal genes involved in HSV-1 infection, and a strong reduction was observed after only 1 min of eye-drop treatment. Collectively, these results suggested the use of ophthalmic solutions as potential antiviral options for the treatment of ocular herpetic infection.

E3 ligase RNF5 inhibits type I interferon response in herpes simplex virus keratitis through the STING/IRF3 signaling pathway

Herpes simplex keratitis (HSK), caused by the herpes simplex virus 1 (HSV-1), is a major blinding disease in developed countries. HSV-1 can remain latent in the host for life and cannot be eradicated. The infection causes the secretion of various cytokines and aggregation of inflammatory cells. In the early stage of inflammation, mainly neutrophils infiltrate the cornea, and CD4⁺ T cells mediate the immunopathological changes in herpetic stromal keratitis in the subsequent progression. The STING/IRF3-mediated type I interferon (IFN) response can effectively inhibit viral replication and control infection, but the activity of STING is affected by various ubiquitination modifications. In this study, we found that the expression of RNF5 was elevated in corneal tissues and corneal epithelial cells after infection with HSV-1. Immunofluorescence staining confirmed that RNF5 was mainly expressed in the corneal epithelial layer. We silenced and overexpressed RNF5 expression in corneal epithelial cells and then inoculated them with HSV-1. We found that the expressions of STING, p-IRF3, p-TBK1, and IFN-β mRNA increased after RNF5 silencing. The opposite results were obtained after RNF5 overexpression. We also used siRNA to silence RNF5 in the mouse cornea and then established the HSK model. Compared with the siRNA-control group, the siRNA-RNF5 group showed significantly improved corneal inflammation, reduced clinical scores and tear virus titers, and significantly increased corneal IFN-β expression. In addition, the expressions of the proinflammatory cytokines IL-6 and TNF-α in the corneal tissue were significantly decreased, indicating that RNF5 silencing could effectively promote IFN-I expression, inhibit virus replication, alleviate inflammation, and reduce corneal inflammatory damage. In summary, our results suggest that RNF5 limits the type I IFN antiviral response in HSV corneal epithelitis by inhibiting STING/IRF3 signaling.

Infectious keratitis: A review

Globally, infectious keratitis is the fifth leading cause of blindness. The main predisposing factors include contact lens wear, ocular injury and ocular surface disease. Staphylococcus species, Pseudomonas aeruginosa, Fusarium species, Candida species and Acanthamoeba species are the most common causal organisms. Culture of corneal scrapes is the preferred initial test to identify the culprit organism. Polymerase chain reaction (PCR) tests and in vivo confocal microscopy can complement the diagnosis. Empiric therapy is typically commenced with fluoroquinolones, or fortified antibiotics for bacterial keratitis; topical natamycin for fungal keratitis; and polyhexamethylene biguanide or chlorhexidine for acanthamoeba keratitis. Herpes simplex keratitis is mainly diagnosed clinically; however, PCR can also be used to confirm the initial diagnosis and in atypical cases. Antivirals and topical corticosteroids are indicated depending on the corneal layer infected. Vision impairment, blindness and even loss of the eye can occur with a delay in diagnosis and inappropriate antimicrobial therapy.

A proof-of-concept study for the efficacy of dispirotripiperazine PDSTP in a rabbit model of herpes simplex epithelial keratitis

Herpes simplex keratitis is an important infectious cause of blindness worldwide. The mainstay of antiviral therapy is treatment with long-established nucleoside analogues orally or topically. However, the emergence of resistant strains may become a major health concern in the future. Therefore, the development of backup antiherpetic medicines is urgently needed. Small molecule PDSTP is known to be active against herpes simplex type 1 strains in vitro, affecting early host-pathogen interactions. Here, we evaluated its preclinical efficacy in a rabbit model of herpes simplex epithelial keratitis. The mean course of keratitis and the corneal lesions in the 1.0% PDSTP gel group was statistically significantly less than in the negative control group and was comparable to that in the aciclovir group. These findings open up new opportunities for the development of antiherpetic drugs with an original mechanism of action.

Optical coherence tomography angiography in herpetic leucoma

BACKGROUND

Herpes simplex virus (HSV) keratitis remains a leading infectious cause of blindness worldwide. Although all forms of HSV keratitis are commonly recurrent, the risk is greatest in stromal keratitis, which is the most likely to result in corneal scarring, thinning, and neovascularization. Recent studies showed the ability of Optical Coherence Tomography Angiography (OCTA) to detect and study vascular abnormalities in the anterior segment, including abnormal corneal vessels. This study intends to investigate the potential of OCTA device to image and describe quantitatively the vascularization in eyes diagnosed with herpetic leucoma and to discuss and review the usefulness of this technique in this pathology.

METHODS

A Cross-sectional study was made, including 17 eyes of 15 patients with leucoma secondary to herpetic keratitis. All eyes underwent anterior segment Slit-Lamp photography (SLP), and OCTA with en-face, b-scans and c-scans imaging. The vessel density (VD) was analyzed in the inferior, nasal and temporal corneal margin in all patients, and in the central area, in eyes with central corneal neovascularization (CoNV). The measurements were calculated after binarization with ImageJ software, using OCTA scans with 6 × 6 mm in a depth of 800 μm.

RESULTS

Patients included had a mean age 53.267 ± 21.542 (years ± SD). The mean total vessel area was 50.907% ± 3.435%. VD was higher in the nasal quadrant (51.156% ± 4.276%) but there were no significant differences between the three analyzed areas (p = 0.940). OCTA was able to identify abnormal vessels when SLP apparently showed no abnormal vessels; OCTA was able to distinguish between larger and smaller vessels even in central cornea; OCTA scans allowed the investigation of several corneal planes and the relation of them with clinical findings.

CONCLUSIONS

OCTA can be useful in both qualitative and quantitative follow-up of patients and may become a non-invasive alternative to objectively monitor treatment response in eyes with corneal vascularization due to herpetic infection.

Herpes Zoster Ophthalmicus: A Devastating Disease Coming Back with Vengeance or Finding Its Nemesis?

Herpes zoster ophthalmicus is a frequent, painful, and debilitating condition caused by the reactivation of the varicella-zoster virus alongside the ophthalmic branch of the trigeminal nerve. Twenty-five percent of adults will develop the disease during their lifetime with the risk increasing to one in two over the age of 50. Herpes zoster ophthalmicus presents with a plethora of ocular manifestations ranging from the characteristic rash in the distribution of the ophthalmic branch of the fifth cranial nerve to more severe keratouveitis, disciform keratitis, and even retinal necrosis. Up to 20% of affected patients develop post-herpetic neuralgia which can persist for years after the acute episode, resulting in potentially devastating consequences for the patient's social, financial, and professional circumstances, as well as their quality of life and daily activities. Shingles prevention studies indicated that the herpes zoster vaccine markedly reduces the burden of the disease, as well as the incidence of both infection and post-herpetic neuralgia. Here we review the vaccinations available for herpes zoster, the reasons behind their limited adoption so far, as well as the future perspectives and challenges associated with this debilitating disease in the era of herpes zoster vaccination and coronavirus disease pandemic.

Release of HSV-1 Cell-Free Virions: Mechanisms, Regulation, and Likely Role in Human-Human Transmission

Herpes simplex virus type 1, or HSV-1, is a widespread human pathogen that replicates in epithelial cells of the body surface and then establishes latent infection in peripheral neurons. When HSV-1 replicates, viral progeny must be efficiently released to spread infection to new target cells. Viral spread occurs via two major routes. In cell-cell spread, progeny virions are delivered directly to cellular junctions, where they infect adjacent cells. In cell-free release, progeny virions are released into the extracellular milieu, potentially allowing the infection of distant cells. Cell-cell spread of HSV-1 has been well studied and is known to be important for in vivo infection and pathogenesis. In contrast, HSV-1 cell-free release has received less attention, and its significance to viral biology is unclear. Here, I review the mechanisms and regulation of HSV-1 cell-free virion release. Based on knowledge accrued in other herpesviral systems, I argue that HSV-1 cell-free release is likely to be tightly regulated in vivo. Specifically, I hypothesize that this process is generally suppressed as the virus replicates within the body, but activated to high levels at sites of viral reactivation, such as the oral mucosa and skin, in order to promote efficient transmission of HSV-1 to new human hosts.

Nanomedicine based approaches for combating viral infections

Millions of people die each year from viral infections across the globe. There is an urgent need to overcome the existing gap and pitfalls of the current antiviral therapy which include increased dose and dosing frequency, bioavailability challenges, non-specificity, incidences of resistance and so on. These stumbling blocks could be effectively managed by the advent of nanomedicine. Current review emphasizes over an enhanced understanding of how different lipid, polymer and elemental based nanoformulations could be potentially and precisely used to bridle the said drawbacks in antiviral therapy. The dawn of nanotechnology meeting vaccine delivery, role of RNAi therapeutics in antiviral treatment regimen, various regulatory concerns towards clinical translation of nanomedicine along with current trends and implications including unexplored research avenues for advancing the current drug delivery have been discussed in detail.

Clinical outcomes of herpes simplex keratitis: Two-year experience from a quaternary eye care centre in Sydney, Australia

PURPOSE

To report anti-viral therapy and outcomes for patients with herpes simplex keratitis (HSK) in a quaternary centre in Sydney, Australia.

METHODS

A retrospective case review of patients who received anti-viral medications for any form of HSK was conducted. Cases were identified from pathology results, pharmacy records and hospital coding data from 2012 to 2013. Clinical details including initial anti-viral treatment and outcome were collated from the medical records. Outcome was determined from when initial anti-viral treatment was stopped or changed, and classified as either clinically resolved, partially resolved or worsened for therapeutic indication; or as either success or failure for prophylaxis.

RESULTS

Anti-viral therapy was given for therapeutic and prophylactic indications at presentation in 252 (85%) and 44 patients (15%), respectively. Topical aciclovir five times daily and valaciclovir in doses ranging from 500 mg to 1 g, one to three times daily were the preferred anti-viral therapies. One hundred and fourteen patients (n = 114/296, 38.5%) also received topical corticosteroids. An outcome was determined for 210/296 (71%) patients. For therapeutic indication, half of the patients (90/174) partially resolved within 8 days, with best outcomes achieved for endothelial HSK (8/11, 73%) and keratouveitis (21/36, 58%). Adverse events, observed in 20% (35/174) of patients, included corneal perforation (n = 8) and secondary bacterial keratitis (n = 6). Prophylaxis with antiviral therapy was successful in two-thirds of patients after 6 months.

CONCLUSIONS

Clinical and visual outcomes varied with the type of HSK and prescribed therapies. Diverse initial anti-viral therapies were identified; standardising them may improve outcomes.

Contact lenses coated with hybrid multifunctional ternary nanocoatings (Phytomolecule-coated ZnO nanoparticles:Gallic Acid:Tobramycin) for the treatment of bacterial and fungal keratitis

Contact lenses are widely used for visual corrections. However, while wearing contact lenses, eyes typically face discomforts (itching, irritation, burning, etc.) due to foreign object sensation, lack of oxygen permeability, and tear film disruption as opposed to a lack of wetting agents. Eyes are also prone to ocular infections such as bacterial keratitis (BK) and fungal keratitis (FK) and inflammatory events such as contact lens-related acute red eye (CLARE), contact lens peripheral ulcer (CLPU), and infiltrative keratitis (IK) caused by pathogenic bacterial and fungal strains that contaminate contact lenses. Therefore, a good design of contact lenses should adequately address the need for wetting, the supply of antioxidants, and antifouling and antimicrobial efficacy. Here, we developed multifunctional gallic acid (GA), phytomolecules-coated zinc oxide nanoparticles (ZN), and phytomolecules-coated zinc oxide nanoparticles + gallic acid + tobramycin (ZGT)-coated contact lenses using a sonochemical technique. The coated contact lenses exhibited significant antibacterial (>log₁₀ 5.60), antifungal, and antibiofilm performance against BK-causing multidrug resistant bacteria (Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia. coli) and FK-related pathogenic fungal strains (Candida albicans, Aspergillus fumigatus, and Fusarium solani). The gallic acid, tobramycin, and phytomolecules-coated zinc oxide nanoparticles have different functionalities (-OH, -NH₂, -COOH, -COH, etc.) that enhanced wettability of the coated contact lenses as compared to that of uncoated ones and further enabled them to exhibit remarkable antifouling property by prohibiting adhesion of platelets and proteins. The coated contact lenses also showed significant antioxidant activity by scavenging DPPH and good cytocompatibility to human corneal epithelial cells and keratinocytes cell lines. STATEMENT OF SIGNIFICANCE: • Multifunctional coated lenses were developed with an efficient sonochemical approach. • Lens surface was modified with nanocoatings of ZnO nanoparticles, gallic acid, and tobramycin. • This synergistic combination endowed the lenses with remarkable antimicrobial activity. • Coated lenses also showed noteworthy antifouling and biofilm inhibition activities. • Coated lenses showed good antioxidant, biocompatibility, and wettability characteristics.

NSC23766 and Ehop016 Suppress Herpes Simplex Virus-1 Replication by Inhibiting Rac1 Activity

Herpes simplex virus-1 (HSV-1) infection of the eyes leads to herpes simplex virus keratitis (HSK), the main cause of infectious blindness in the world. As the current therapeutics for HSV-1 infection are rather limited and prolonged use of acyclovir (ACV)/ganciclovir (GCV) and in immunocompromised patients lead to the rise of drug resistant mutants, it underlines the urgent need for new antiviral agents with distinct mechanisms. Our study attempted to establish ras-related C3 botulinum toxin substrate 1 (Rac1) as a new therapeutic target for HSV-1 infection by using Rac1-specific inhibitors to evaluate the in vitro inhibition of virus growth. Our results showed that increased Rac1 activity facilitated HSV-1 replication and inhibition of Rac1 activity by NSC23766 and Ehop016 significantly reduced HSV-1 replication. Thus, we identified NSC23766 and Ehop016 as possessing potent anti-HSV-1 activities by suppressing the Rac1 activity, suggesting that Rac1 is a potential target for treating HSV-1-related diseases.

Acyclovir-Loaded Nanoemulsions: Preparation, Characterization and Irritancy Studies for Ophthalmic Delivery

Objective: The main goal of the present work was to develop and evaluate nanoemulsions (NEs) containing acyclovir (ACV) for ophthalmic drug delivery.Method: Firstly, component screening was performed by determining ACV solubility in various oils, surfactants, and co-surfactants. Different NE formulations were developed based on pseudo-ternary phase diagrams, and physicochemical assets were evaluated. Selected formulations were subjected to the drug release efficacy, stability studies, and ex-vivo trans-corneal permeation test. The safety of NEs was investigated by the modified Draize test and hen's egg test-chorioallantoic membrane (HET-CAM).Results: Based on the solubility studies, Tween 20, Triacetin, and Tramsectol^®P were chosen to prepare NE formulations. Developed NEs showed desirable physiochemical properties, including a droplet size of less than 15 nm. Selected formulations (F1 and F2) exhibited a sustained drug release pattern compared to the control group (P < .001). ACV penetration from F1 and F2 to the excised bovine cornea was 2.85 and 2.9-fold more than the control, respectively. Furthermore, HET-CAM and modified Draize test confirmed that F1 and F2 were safe for ocular administration.Conclusion: Present investigation revealed that ACV-loaded NEs could be effective, and safe platform for ophthalmic delivery of ACV.

Quantitative real-time polymerase chain reaction analysis in herpes simplex virus keratitis with and without epithelial involvement

PURPOSE

To evaluate the quantitative real-time polymerase chain reaction (qRT-PCR) analysis in herpes simplex virus (HSV) keratitis with and without epithelial involvement.

METHODS

This cross-sectional study was performed on 70 patients with different HSV types and an active ocular lesion in Farabi Eye Hospital, Tehran, Iran. From these 70 patients, 171 samples were collected, including seventy tear samples and 33 scraping samples from involved eyes; and 68 samples from uninvolved fellow eyes. Samples were frozen at - 70 °C until DNA extraction was performed. Quantity of HSV was measured using qRT-PCR in all three samples.

RESULTS

The mean age of HSV patients was 52.19 ± 20.42 years (range, 4-85 years). Forty-one (58.6%) HSV patients had epithelial involvement, and 29 (41.4%) patients did not have epithelial involvement. In PCR-positive cases, the mean number of viruses in affected eyes' tears (8,831,234 ± 4,051,979) was significantly higher than uninvolved eyes' tears (182,603 ± 69,141) (P = 0.02). The mean of PCR in HSV patients with and without epithelial involvement was 10,320,269 ± 5,329,800 and 1,469,419 ± 1,070,396, respectively (P = 0.04). The qRT-PCR of involved tears in both groups (with and without epithelial involvement) was significantly higher than unaffected eyes' tears (P < 0.0001 and P = 0.01, respectively). In cases with and without epithelial involvement, the cutoff points of viral load in involved eyes' tears were 281,000 and 126,000 copies, respectively.

CONCLUSION

The results indicated that qRT-PCR is an excellent method for the detection of herpes simplex keratitis.

Novel Application of Hot Melt Extrusion Technology for Preparation and Evaluation of Valacyclovir Hydrochloride Ocular Inserts

The objective of this study was to investigate the processability of hot-melt extrusion (HME) to formulate ocular inserts of valacyclovir hydrochloride and evaluate the in vivo bioavailability of the formulation. To optimize the formulation of this drug, different physical mixtures of the polymers and plasticizer were prepared. The physical mixture was extruded through a co-rotating twin-screw extruder, and the obtained ocular inserts were cut with dimensions of 4 mm × 2 mm × 1 mm to enhance the formulation instillation in the eye. Ocular inserts were evaluated for drug content, weight variation, uniformity of thickness, in vitro drug release, and in vivo drug bioavailability. The ocular inserts were thermally characterized using differential scanning calorimetry (DSC). The attributes observed for the ocular inserts were within the target specifications. The ocular inserts of valacyclovir hydrochloride were successfully prepared using the HME. They provided sustained drug release along with enhanced drug permeation when compared with the eyedrop solution and dissolve completely in 8 h. Additionally, the obtained results demonstrated that the formulation of ocular inserts of valacyclovir hydrochloride using HME was reproducible, robust, and effective method.

Preventive Vaccination with Mesenchymal Stem Cells Protects Mice from Lethal Infection Caused by Herpes Simplex Virus 1

Herpes simplex viruses 1 and 2 (HSV-1 and HSV-2) infect almost all organs and tissues, cause genital herpes-the most common sexually transmitted disease-disorders of the central nervous system (CNS), and lead to severe complications in children. Despite the available drugs, the incidence of HSV-1/2 continues to rise. None of the prophylactic vaccine candidates have shown a protective effect in trials nor approval for use in clinical practice. We have investigated the protective properties of mesenchymal stem cells (MSC) isolated from the bone marrow of mice. A comparative analysis of the protective response to the introduction of primary and modified MSCs (mMSC) was carried out using the plasmid containing gene of the HSV and an inactivated virus in a model of lethal HSV-1 infection in mice. mMSCs were obtained by transfection of the Us6 gene encoding glycoprotein D (gD) of the HSV, the plasmid contained the same gene. After twofold immunization with primary MSCs, the formation of antibodies interacting with the viral antigen (according to enzyme immunoassay data) and neutralizing the infectious activity of HSV-1 in the reaction of biological neutralization was observed in the peripheral blood of mice. In addition, the introduction of primary MSCs induced the production of interferon gamma (INF-γ) which is detected in the peripheral blood of mice. After infection with HSV-1, the immunized mice showed significantly increased titers of virus-specific antibodies, an increased level of IFNγ, and were completely protected from lethal HSV-1 infection. The protective effect of the other three immunogens was lower and did not exceed 50-65%. Considering the wide availability of MSCs, the proven safety of intravenous administration, and the results obtained in this work on the ability to induce innate, adaptive and protective immunity to HSV-1, MSCs can be considered a promising basis for the development of new cellular vaccines for the prevention of herpesvirus and other viral infections.

Corneal Graft Success Rates in HSV Keratitis: A Systematic Review

Herpes Simplex Virus (HSV) has worldwide prevalence. The primary objective of this systematic review was to compare penetrating keratoplasty (PK) and deep anterior lamellar keratoplasty (DALK) regarding the efficacy and complications of the treatment of corneal scarring caused by herpes simplex keratitis. Out of the 469 articles identified during the combined search of the literature based on the PubMed and Cochrane libraries, 10 retrospective and 2 prospective studies published from January 2010 to December 2019 were included. The study outcomes indicated that both surgical approaches resulted in a comparable improvement of visual acuity (VA). However, DALK demonstrated fewer complications in the majority of studies. Higher graft survival rates were associated with higher acyclovir (ACV) doses (above 800 mg/day), topical steroid and antibiotic drops. In conclusion, in terms of postoperative VA, both PK and DALK demonstrate comparable efficacy. However, DALK, which is applied in less severe HSK cases, is associated with fewer complications and better graft survival rates. High dosages of ACV, topical steroids and antibiotics contribute significantly to improved postoperative outcomes.

Advancement on Sustained Antiviral Ocular Drug Delivery for Herpes Simplex Virus Keratitis: Recent Update on Potential Investigation

The eyes are the window to the world and the key to communication, but they are vulnerable to multitudes of ailments. More serious than is thought, corneal infection by herpes simplex viruses (HSVs) is a prevalent yet silent cause of blindness in both the paediatric and adult population, especially if immunodeficient. Globally, there are 1.5 million new cases and forty thousand visual impairment cases reported yearly. The Herpetic Eye Disease Study recommends topical antiviral as the front-line therapy for HSV keratitis. Ironically, topical eye solutions undergo rapid nasolacrimal clearance, which necessitates oral drugs but there is a catch of systemic toxicity. The hurdle of antiviral penetration to reach an effective concentration is further complicated by drugs’ poor permeability and complex layers of ocular barriers. In this current review, novel delivery approaches for ocular herpetic infection, including nanocarriers, prodrugs, and peptides are widely investigated, with special focus on advantages, challenges, and recent updates on in situ gelling systems of ocular HSV infections. In general congruence, the novel drug delivery systems play a vital role in prolonging the ocular drug residence time to achieve controlled release of therapeutic agents at the application site, thus allowing superior ocular bioavailability yet fewer systemic side effects. Moreover, in situ gel functions synergistically with nanocarriers, prodrugs, and peptides. The findings support that novel drug delivery systems have potential in ophthalmic drug delivery of antiviral agents, and improve patient convenience when prolonged and chronic topical ocular deliveries are intended.

Adverse Events of Intense Pulsed Light Combined With Meibomian Gland Expression Versus Meibomian Gland Expression in the Treatment of Meibomian Gland Dysfunction

BACKGROUND AND OBJECTIVE

To analyze the occurrence and causes of adverse events (AEs) in intense pulsed light (IPL) combined with meibomian gland expression (MGX) and MGX treatment alone for meibomian gland dysfunction (MGD).

STUDY DESIGN/MATERIALS AND METHODS

A retrospective study was conducted on MGD patients treated in Wuhan Aier Hankou Eye Hospital from February 2018 to October 2019 to compare the AEs between IPL-MGX and MGX groups. Relevant AEs that occurred during the treatment and within 1 month after the patients' last treatment were recorded and the causes of the AEs were analyzed.

RESULTS

A total of 2,282 patients received IPL-MGX and 1,407 received MGX treatment. No serious AEs occurred in both groups. There were 74 AEs in the IPL-MGX group, with an incidence of 3.24%, including 14 significant AEs (2 cases of epidemic keratoconjunctivitis, 1 recurrent herpes simplex keratitis (HSK), 9 new onsets of floaters, 1 recurrent glaucomatocyclitic crises, and 1 recurrent iridocyclitis). There were 27 AEs in the MGX group with a rate of 1.92%, including 4 significant AEs (2 cases of keratoconjunctivitis epidemic, 2 new cases of floaters). Compared with the IPL-MGX group, the incidence of AEs in the MGX group was lower (P = 0.017).

CONCLUSIONS

Both IPL-MGX and MGX treatment are safe therapies with low risk for AEs. IPL treatment is not recommended for young children (age 10 or less) as well as patients with anterior uveitis or glaucomatocyclitic crises. The previous history of HSK and eyes with high myopia are advised to exercise caution in IPL treatment. Lasers Surg. Med. © 2020 Wiley Periodicals LLC.

Ocular cytology: Diagnostic features and ongoing practices

Ocular cytology specimens are small, with limited options for a repeat biopsy. Appropriate handling of these specimens and triaging for ancillary testing can be taxing. In this article, the author reviews a selection of potentially challenging diagnoses and current common practices and methods used in diagnosing ocular diseases by cytology. The majority of cytology specimens submitted for evaluation of ocular diseases can be divided into 3 major categories: surface epithelial corneal and conjunctival cytology samples, intraocular fluids from the anterior (aqueous fluid) or posterior (vitreous fluid) chambers of the eye, and intraocular fine-needle aspiration specimens. The clinical findings, testing, and cytologic features of ocular surface epithelial infections, inflammations and neoplasia are discussed; and challenges in processing and diagnosing intraocular infections, chronic uveitis, and vitreoretinal lymphoma are reviewed. Novel molecular testing in the cytologic diagnosis and classification of uveal melanoma also is explored. Cytology evaluation of corneal epithelial and stromal cells, anterior chamber and vitreous samples, and fine-needle aspiration biopsies can provide detailed diagnostic findings to aid in the treatment and follow-up of patients with ocular diseases.

A synthetic stigmastane displays antiadenoviral activity and reduces the inflammatory response to viral infection

Although human adenovirus (ADV) infections are mild and self-limited in immunocompetent individuals, they can be severe and life-threatening in immunocompromised patients. Despite their significant clinical impact, there are not currently approved antiviral therapies for ADV infections. On the other hand, in some cases, the immune response induced by ADV infection can cause tissue damage. Even more, in the case of adenovirus vectors used in gene therapy, host immunity generally antagonize viral efficacy. Therefore, the need for searching an effective and safe therapy is increasing. In this work, we describe the antiadenoviral activity of the synthetic stigmastane (22S, 23S)-22,23-dihydroxystigmast-4-en-3-one (Compound 1) with already reported antiviral and antiinflammatory activities against other viruses of clinical importance. Compound 1 displayed no virucidal activity and did not affect ADV entry to the cells. The compound inhibited viral replication and it also reduced cytokine secretion in epithelial and inflammatory infected cells. Thus, Compound 1 would be a promissory drug potentially useful against adenoviral infections as well as an adjuvant of adenoviral vectors in gene therapy.

Imprinted Contact Lenses for Ocular Administration of Antiviral Drugs

A variety of ocular diseases are caused by viruses, and most treatments rely on the use of systemic formulations and eye drops. The efficient ocular barriers that oppose antiviral drug penetration have prompted the development of improved topical delivery platforms. The aim was to design hydrogel contact lenses endowed with an affinity for acyclovir (ACV) and its prodrug valacyclovir (VACV), first-choice drugs against herpes simplex virus (HSV) ocular keratitis, and that can sustain the release of therapeutic doses during daily wearing. Functional monomers suitable for interaction with these drugs were screened using computational modeling. Imprinted and non-imprinted hydrogels were prepared with various contents in the functional monomer methacrylic acid (MAA) and characterized in terms of swelling, transmittance, mechanical properties, and ocular compatibility (hen’s egg test on chorioallantoic membrane (HET-CAM) assay). The values were in the range typical of soft contact lenses. Compared to ACV, the capability to load VACV was remarkably higher due to stronger electrostatic interactions with MAA. The advantages of the imprinting technology were evidenced for VACV. Stability of VACV loading solution/hydrogels under steam heat sterilization and subsequent drug release was investigated. Permeability studies through bovine and porcine cornea and sclera of the drug released from the hydrogels revealed that VACV accumulates in the cornea and can easily cross the sclera, which may facilitate the treatment of both anterior and posterior eye segments diseases.

Recent progress and strategies to develop antimicrobial contact lenses and lens cases for different types of microbial keratitis

Although contact lenses are widely used for vision correction, they are also the primary cause of a number of ocular diseases such as microbial keratitis (MK), etc. and inflammatory events such as infiltrative keratitis (IK), contact lens acute red eye (CLARE), contact lens-induced peripheral ulcer (CLPU), etc. These diseases and infiltrative events often result from microbial contamination of lens care solutions and lens cases that can be exacerbated by unsanitary lens care and extended lens wear. The treatment of microbial biofilms (MBs) on lens cases and contact lenses are complicated and challenging due to their resistance to conventional antimicrobial lens care solutions. More importantly, MK caused by MBs can lead to acute visual damage or even vision impairment. Therefore, the development of lens cases, lens care solutions, and contact lenses with effective antimicrobial performance against MK will contribute to the safe use of contact lenses. This review article summarizes and discusses different chemical approaches for the development of antimicrobial contact lenses and lens cases employing passive surface modifications, antimicrobial peptides, free-radical fabricating agents, quorum sensing quenchers, antibiotics, antifungal drugs and various metals and coatings with antimicrobial nanomaterials. The benefits and shortcomings of these approaches are assessed, and alternative solutions for future developments are discussed.

Bacterial Pigment Prodigiosin Demonstrates a Unique Antiherpesvirus Activity That Is Mediated through Inhibition of Prosurvival Signal Transducers

Herpes simplex virus (HSV) is among the most prevalent viral infections worldwide and remains incurable. While nucleoside analogs are used to relieve symptoms of infection, they suffer from having serious adverse effects and are unable to abolish the virus from the host. Here, we demonstrate a unique antiviral effect of prodigiosin (PG), a natural secondary metabolite produced by Serratia marcescens, on HSV infection. We show that PG naturally exerts antiviral activity against HSV-1 and HSV-2 infections. PG treatment resulted in robust inhibition of viral replication in vitro and ex vivo in cultured porcine corneas. Additionally, PG protected against HSV-1 infection and disease progression in a murine model of ocular infection. In our quest to determine the molecular mechanisms of its antiviral activity, we show that PG specifically inhibits NF-κB and Akt signaling pathways and promotes accelerated cell death in HSV-infected cells. Our findings reveal novel antiviral properties of PG, suggesting its high potential as an alternative treatment for herpetic diseases. They also provide new information on antiviral effects of HSV-bacterial metabolite interactions.IMPORTANCE In this article, we provide a new role for a commonly found bacterial pigment in controlling herpes simplex virus infection, for which diverse and multimodal antiviral agents are needed to prevent drug resistance. Serratia marcescens is a red pigment (prodigiosin)-producing Gram-negative bacillus that is naturally found in soil and water. It is associated with many kinds of human infections, including wound and eye infections, and meningitis. Taking cues from previous studies on prodigiosin, including possible proapoptotic anticancer properties, we investigated how it might affect HSV infection. Interestingly, we found that it is a potent virucidal compound that disrupts host signaling pathways needed for HSV growth and survival. The mode of antiviral action suggests potentially broad activity against enveloped viruses. Our results also indicate that interactions with commensal bacteria may inhibit HSV infection, underscoring the importance of studying these microbial metabolites and their implications for viral pathogenesis and treatment.

Single AAV-Mediated CRISPR-SaCas9 Inhibits HSV-1 Replication by Editing ICP4 in Trigeminal Ganglion Neurons

Herpes simplex keratitis (HSK) is the most common cause of corneal blindness in developed nations, caused by primary or recurrent herpes simplex virus 1 (HSV-1) infection of the cornea. Latent infection of HSV-1, especially in the trigeminal ganglion (TG), causes recurrence of HSV-1 infection. As antiviral treatment is not effective on latent HSV-1, to test the possibility of inhibiting HSV-1 by SpCas9 (Streptococcus pyogenes Cas9) or SaCas9 (Staphylococcus aureus Cas9), ICP0 and ICP4, two important genes required for HSV-1 replication and reactivation, were chosen as targets. In Vero cells, SpCas9 and SaCas9 targeting ICP0 or ICP4 can effectively inhibit the proliferation of HSV-1 without affecting cell viability. No significant guide RNA (gRNA)-dependent off-targets were observed in the human genome by digenome sequencing and deep sequencing verification. Adeno-associated virus 1 (AAV1)-mediated delivery of SaCas9 inhibits HSV-1 replication by targeting ICP4 in mouse primary TG neuronal cells. SpCas9 and SaCas9 are able to inhibit HSV-1 infection in Vero cells and mouse TG neuronal cultures with high efficiency and good biosafety. AAV1-mediated delivery of SaCas9 shows great potential in treating HSK and inhibiting HSV-1 in TG neurons. Further investigations may be needed to test the inhibition of latent infections, which may result in the development of novel methods for treating viral diseases.

Shotgun sequencing to determine corneal infection

Purpose

To investigate if shotgun-sequencing method could be useful in detailed diagnosis of herpes simplex virus (HSV) infection and compare it with the conventional diagnostic method.

Observations

Using a sterile scraper, the infectious part of the ocular surface was scraped gently and placed on a glass slide for conventional diagnosis using PCR and histology and in RNA stabilizing reagent for shotgun sequencing respectively. Concentration of the DNA was determined using a sensitive fluorescence dye-based Qubit dsDNA HS Assay Kit. Shotgun-sequencing libraries were generated using the NEBNext DNA ultra II protocol. The samples were sequenced on the Illumina NextSeq 500 in high output mode with 2X150 bp paired-end sequencing. Taxonomic and functional profiles were generated.

Conventional diagnostic method suspected herpetic keratitis. The results indicated presence of an amplified product of 92 bp positive HSV-DNA. Conventional diagnostic method detected the presence of Herpes Simplex Virus DNA (type 1). Shotgun sequencing confirmed the diagnosis of HSV along with the taxonomical profiling of the virus. These results were achieved using 1.9 ng/μL of DNA concentration (114 ng in 60 μL) of the total sample volume.

Conclusions and importance

Shotgun sequencing is a hypothesis-free approach that identifies full taxonomic and functional profile of an organism. This technology is advantageous as it requires smaller sample size compared to conventional diagnostic methods.

Protective effect of total flavonoids from Ixeris Sonchifolia on herpes simplex virus keratitis in mice

Background

To investigate the protective effect of Ixeris Sonchifolia (Bae.) Hance (ISH) extract on herpes simplex virus keratitis (HSK) in mice.

Methods

A mouse model of HSK was established by inoculating 60 mice (60 right eyes) with herpes simplex virus type 1 (HSV-1) by corneal scratch. The other 15 mice as blank control only received corneal scratch but without HSV-1. From the 2nd day after the successful modeling, the experimental group was fed with ISH total flavonoids (50, 100 and 200 mg/kg) orally, twice a day for 14 days. The model group and control group were given the same amount of normal saline. The pathological changes of cornea were observed once a day by slit lamp microscopy combined with fluorescein staining. The corneal histopathological examination, the survival status and the serum levels of interleukin-2 (IL-2), IL-4 and interferon-gama (INF-γ) were performed at the end of the experiment.

Results

The result showed that ISH could significantly improve the corneal lesion degree, increase mice survival rate, and markedly increase the levels of IL-2 and INF-γ, reduce the levels of IL-4 in serum of mice.

Conclusions

ISH could increase the anti-virus ability, promote the healing of corneal inflammation and alleviate the pathological damage of cornea, which suggested that ISH has a potential and valuable therapeutic effect on the HSK.

Lipopolysaccharide enhances human herpesvirus 1 replication and IL-6 release in epithelial cells

OBJECTIVE

To investigate the effect of lipopolysaccharide (LPS) on human herpesvirus 1 (HHV-1) infection in epithelial cells.

METHODS

Two strains of HHV-1, HHV-1 F strain (HHV-1f) and HHV-1 strain-H129 with GFP knock-in (HHV-g4), were used to infect HCE-T and VERO cells at MOIs of 0.04 and 0.02, respectively. After 1 h, 0, 10, 50, and 100 μg/ml LPS was added to serum-free medium and the cells were cultured for up to 24 h. GFP fluorescence of HHV-g4 in cells was examined under a fluorescence microscope and imaged. HHV-1f titer was determined by quantitative real-time polymerase chain reaction (qPCR) in HCE-T cells and plaque assays in VERO cells. The expression of the viral ICP4 protein of HHV-1f was detected by Western blot assay. IL-6 and IL-10 levels in culture medium were determined by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Similar changes but at different degrees were found in HCE-T and VERO cells that were infected with HHV-1. GFP fluorescence of HHV-g4 and cell lesions increased in a dose-dependent manner. Virus titer was also enhanced by LPS stimulation in HCE-T and VERO cells. ICP4 expression was promoted at higher LPS concentrations (P = 0.04). In addition, viral infection resulted in increased expression of IL-6 in a dose-dependent manner at 12 and 24 h (P = 0.01), while IL-10 expression was unaffected by either HHV-1 infection or LPS stimulation.

CONCLUSION

LPS promotes HHV-1 infection in epithelial cells, which suggests that gram-negative bacteria on ocular surfaces may aggravate HHV-1 infection.

The Spectrum of Microbial Keratitis: An Updated Review

Background:

In microbial keratitis, infection of the cornea can threaten vision through permanent corneal scarring and even perforation resulting in the loss of the eye. A literature review was conducted by Karsten, Watson and Foster (2012) to determine the spectrum of microbial keratitis. Since this publication, there have been over 2600 articles published investigating the causative pathogens of microbial keratitis.

Objective:

To determine the current spectrum of possible pathogens implicated in microbial keratitis relative to the 2012 study.

Methods:

An exhaustive literature review was conducted of all the peer-reviewed articles reporting on microbial pathogens implicated in keratitis. Databases including MEDLINE, EMBASE, Scopus and Web of Science were searched utilising their entire year limits (1950-2019).

Results:

Six-hundred and eighty-eight species representing 271 genera from 145 families were implicated in microbial keratitis. Fungal pathogens, though less frequent than bacteria, demonstrated the greatest diversity with 393 species from 169 genera that were found to cause microbial keratitis. There were 254 species of bacteria from 82 genera, 27 species of amoeba from 11 genera, and 14 species of virus from 9 genera, which were also identified as pathogens of microbial keratitis.

Conclusion:

The spectrum of pathogens implicated in microbial keratitis is extremely diverse. Bacteria were most commonly encountered and in comparison, to the review published in 2012, further 456 pathogens have been identified as causative pathogens of microbial keratitis. Therefore, the current review provides an important update on the potential spectrum of microbes, to assist clinicians in the diagnosis and treatment of microbial keratitis.

Nerve growth factor inhibits TLR3-induced inflammatory cascades in human corneal epithelial cells

Background

In herpes simplex epithelial keratitis, excessive TLR3-induced cellular responses after virus infection evoke inflammatory cascades that might be destructive to the host cornea. Nerve growth factor (NGF), a pluripotent neurotrophic factor with immune regulatory effect, was proved to be effective in Herpes simplex keratitis (HSK) treatment, although the detailed mechanisms remain unclear. This study aims to investigate the effects of NGF on modulating inflammatory responses triggered by TLR3 activation in human corneal epithelial cells (HCECs) in vitro.

Methods

HCECs were stimulated with TLR3 agonist, poly(I:C), in the absence or presence of NGF. Cell viability and cytotoxicity were measured by a CCK-8 assay and LDH release assay, respectively. The activation of NF-κB signaling pathway was examined using immunofluorescence staining and western blotting. Levels of proinflammatory cytokines were determined by ELISA or RT-qPCR. ROS generation and 8-OHdG positive cells were examined by a fluorometric analysis.

Results

It was shown that NGF significantly inhibited the generation of proinflammatory cytokines in HCECs triggered by TLR3 activation (P < 0.05), probably via suppressing NF-κB activation. NGF also impeded the upstream signal to initiate NF-κB activation by scavenging ROS by approximately 50% (P < 0.05). In addition, 8-OHdG positive cells were substantially attenuated by NGF treatment (P < 0.01).

Conclusions

Taken together, this study indicates that NGF could inhibit TLR3-induced inflammatory cascades in HCECs, suggesting NGF as a potential therapeutic agent for HSK.

Topical Tacrolimus as an adjunct to Conventional Therapy for Stromal Herpetic Keratitis: a Randomized Clinical Trial

Purpose

This study investigates the effects of 0.05% topical tacrolimus as an adjunct therapy for patients with non-necrotizing herpetic stromal keratitis (HSK).

Methods

Patients with non-necrotizing HSK, referred to the Cornea Clinic at Hospital in Rasht, Iran, between September 2016 and February 2018, were randomly assigned to two groups. The case group (N = 25) and the control group (N = 25) received conventional treatment with systemic acyclovir and topical prednisolone. The case group (N = 25) additionally received 0.05% tacrolimus eye drops four times a day for one month. Complete ocular examinations, including best-corrected visual acuity (BCVA) assessment, intraocular pressure (IOP) measurement, slit lamp biomicroscopy, and photo slit lamp imaging, were performed before treatment, and 3, 7, 14, 21, and 28 days after the intervention.

Results

The mean age of the patients was 46.2 ± 12.9 years, and 70% of the patients were male. There was no difference between the groups in terms of age, sex, and baseline ocular measurements (P> 0.05). The case group had a lower mean logarithm of the minimum angle of resolution (LogMAR) for BCVA, lower grading scores, and steeper decreasing trends for corneal haziness, edema, neovascularization, and epitheliopathy compared to the control group after the second week (P< 0.05), while IOP remained unchanged between groups (P> 0.05).

Conclusion

The addition of 0.05% topical tacrolimus enhances visual acuity and reduces corneal inflammation, neovascularization, and scarring; thus, it can used as an appropriate adjunct treatment for patients with HSK.

Prior inhibition of AKT phosphorylation by BX795 can define a safer strategy to prevent herpes simplex virus-1 infection of the eye

PURPOSE

To evaluate the prophylactic antiviral efficacy, corneal tolerance and toxicity of topically dosed BX795, a non-nucleoside small-molecule inhibitor of herpes simplex virus type-1 (HSV-1).

METHODS

Prophylactic treatment with BX795 was performed both in-vitro on human corneal epithelial cells and in-vivo on mice prior to HSV-1 challenge. Viral burden was evaluated using a standard plaque assay. In a separate experiment, mice were treated topically 3-times daily for 4-weeks with BX795 to evaluate corneal tolerance and toxicity. Phenol-red thread measurements, fluorescein staining and optical coherence tomography (OCT) were used to evaluate tear production, dryness and corneal structural changes. Corneal sensitivity and intraocular pressure were measured using esthesiometery and tonometery respectively.

RESULTS

Both in-vitro and in-vivo results showed a robust suppression of HSV-1 infection when treated prophylactically with BX795. The fluorescein stain and phenol-red results for the BX795-treated eyes did not show signs of corneal surface dryness when compared to trifluridine (TFT), an FDA-approved topical antiviral. The OCT measurements showed no signs of structural changes to the cornea suggesting that BX795 treatment was well tolerated without any apparent signs of toxicity or inflammation. The corneal sensitivity of BX795-treated eyes was not significantly different from TFT-treated eyes. No significant increase in the intraocular pressure of BX795-treated mice was observed.

CONCLUSIONS

Prophylactic treatment with BX795 protects corneal cells from HSV-1 infection. The antiviral is well-tolerated on murine corneas without any detectable toxicity.