Pathogenesis and management of herpes simplex virus keratitis

Bilateral Multiple Herpetic Epithelial Keratitis: A Case Report and Review of the Literature

Herpetic epithelial keratitis is a viral infection of the cornea caused by the herpes simplex virus (HSV). It typically presents as a unilateral disease. Bilateral involvement is a rare manifestation of herpetic epithelial keratitis, accounting for only a small percentage of cases. By sharing this case, we aim to contribute to the understanding of bilateral herpetic epithelial keratitis and stimulate further research in this area to optimize patient care and outcomes A 13-year-old child, a known case of atopy, presented to the ophthalmology clinic with a complaint of pain, photophobia, and redness in the right eye (OD) for three days. The patient was diagnosed as a case of bilateral herpetic epithelial keratitis; he was started on moxifloxacin eye drops four times a day, Artelac (sodium hyaluronate) every two hours, carbomer HS, ganciclovir ointment five times per day. Bilateral herpetic epithelial keratitis is a rare manifestation of HSV infection, and its management poses unique challenges compared to unilateral disease. The diagnosis of bilateral herpetic epithelial keratitis is primarily based on clinical findings, including bilateral dendritic or geographic ulcers on the cornea. Fluorescein staining is a valuable tool for visualizing corneal ulcers. In our case, the presence of bilateral dendritic ulcers in the absence of significant anterior chamber inflammation supported the diagnosis of bilateral herpetic epithelial keratitis Despite the limited literature on bilateral herpetic epithelial keratitis, the principles of management remain consistent with those of unilateral disease. Early recognition, prompt initiation of antiviral therapy, and close follow-up are crucial for successful outcomes.

Macrophage migration inhibitory factor receptor CD74 expression is associated with expansion and differentiation of effector T cells in COVID-19 patients

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused millions of COVID-19 cases and deaths worldwide. Severity of pulmonary pathologies and poor prognosis were reported to be associated with the activation non-virus-specific bystander T cells. In addition, high concentrations of the macrophage migration inhibitory factor (MIF) were found in serum of COVID-19 patients. We hypothesized that these two pathogenic factors might be related and analyzed the expression of receptors for MIF on T cells in COVID-19. T cells from PBMCs of hospitalized patients with mild and severe COVID-19 were characterized. A significantly higher proportion of CD4+ and CD8+ T cells from COVID-19 patients expressed CD74 on the cell surface compared to healthy controls. To induce intracellular signaling upon MIF binding, CD74 forms complexes with CD44, CXCR2, or CXCR4. The vast majority of CD74+ T cells expressed CD44, whereas expression of CXCR2 and CXCR4 was low in controls but increased upon SARS-CoV-2 infection. Hence, T cells in COVID-19 patients express receptors that render them responsive to MIF. A detailed analysis of CD74+ T cell populations revealed that most of them had a central memory phenotype early in infection, while cells with an effector and effector memory phenotype arose later during infection. Furthermore, CD74+ T cells produced more cytotoxic molecules and proliferation markers. Our data provide new insights into the MIF receptor and co-receptor repertoire of bystander T cells in COVID-19 and uncovers a novel and potentially druggable aspect of the immunological footprint of SARS-CoV-2.

Herpes simplex keratoconjunctivitis in the immediate postoperative period after strabismus surgery

The authors describe the case of bilateral herpes simplex keratoconjunctivitis (HSK) following uncomplicated 7 mm bilateral lateral rectus recessions in a 3-year-old child. The recovery was initially unremarkable, and the standard postoperative drops of dexamethasone and chloramphenicol (non-preservative free) were prescribed. The child presented 8 days postoperatively with fever, right upper lid swelling and ptosis. She was admitted for intravenous antibiotics for suspected pre-septal cellulitis. Over the next 2 days, she deteriorated with bilateral lid involvement. An examination under anesthesia (EUA) revealed bilateral corneal epithelial (dendritic and geographical) ulcers with conjunctival erosions and pseudo membranes prompting a diagnosis of HSK. This was confirmed by polymerase chain reaction (PCR) testing. The child recovered within 2 weeks after starting oral and topical antiviral medication. This case highlights the importance of EUA in infections not responding to standard treatment. Although HSK is known to occur after topical steroid use and ocular surgery, we were not able to find any other cases in the literature and believe this is the first reported case of bilateral HSK in the immediate postoperative period after strabismus surgery.

Bystander CD4+ T cells: crossroads between innate and adaptive immunity

T cells are the central mediators of both humoral and cellular adaptive immune responses. Highly specific receptor-mediated clonal selection and expansion of T cells assure antigen-specific immunity. In addition, encounters with cognate antigens generate immunological memory, the capacity for long-term, antigen-specific immunity against previously encountered pathogens. However, T-cell receptor (TCR)-independent activation, termed “bystander activation”, has also been found. Bystander-activated T cells can respond rapidly and secrete effector cytokines even in the absence of antigen stimulation. Recent studies have rehighlighted the importance of antigen-independent bystander activation of CD4⁺ T cells in infection clearance and autoimmune pathogenesis, suggesting the existence of a distinct innate-like immunological function performed by conventional T cells. In this review, we discuss the inflammatory mediators that activate bystander CD4⁺ T cells and the potential physiological roles of these cells during infection, autoimmunity, and cancer.

Immune cells that become activated in the absence of antigen stimulation could be harnessed in the fight against infection, autoimmunity, and cancer. Je-Min Choi and colleagues from Hanyang University in Seoul, South Korea, review how the immune system can deploy helper T cells through an unusual process called bystander activation. Most T cells become activated only after receptors on their surface bind to specific cognate antigen. In contrast, bystander T cells are activated non-specifically in response to cytokines and other pro-inflammatory mediators. Studies have shown that this cell population has a variety of protective and pathogenic functions, for example, guarding against multiple sclerosis, aggravating the symptoms of parasitic infections and promoting antitumor immunity. A better understanding of these immune cells could lead to new therapeutic options for these diseases.

HSV-1 infection and pathogenesis in the tree shrew eye following corneal inoculation

Herpes simplex virus type I (HSV-1) infection causes inflammation in the cornea known as herpes simplex virus keratitis (HSK), a common but serious corneal disease. It is not entirely clear whether the virus during recurring infection comes from the trigeminal ganglia or the eye tissue, including the retina and ciliary ganglion. Because the tree shrew is closely related to primates and tree shrew eye anatomic structures are similar to humans, we studied HSV-1 corneal infection in the tree shrew. We found that HSK symptoms closely mimic those found in human HSK showing typical punctiform and dendritic viral keratitis during the acute infection period. Following the HSV-specific lesions, complications such as stromal scarring, corneal thickening (primary infection), opacity, and neovascularization were observed. In the tree shrew model, following ocular inoculation, the cornea becomes infected, and viral protein can be detected using anti-HSV-1 antibodies in the epithelial layer and retina neuronal ganglion cells. The HSV-1 transcripts, ICP0, ICP4, and LAT can be detected at 3 days post-infection (dpi), peaking at 5 dpi. After 2 weeks, ICP4 and ICP0 transcripts are reduced to a basal level, but the Latency Associated Transcripts (LATs) continue to accumulate. Interestingly, after the acute infection, we still detected abundant active HSV-1 in tree shrew eyes. Further, we found HSV-1 persistent in the ciliary ganglion and cornea. These findings are discussed in support of the tree shrew as a non-human primate HSK model, which could be useful for mechanistic studies of HSK.

Approaches toward enhancing survival probability following deep anterior lamellar keratoplasty

The greatest advantage of deep anterior lamellar keratoplasty over full-thickness corneal transplantation is the elimination of graft failure caused by endothelial rejection. Despite this advantage, a deep anterior lamellar keratoplasty graft can fail because of several factors, such as complications related to the donor-recipient interface, graft epithelial abnormalities, graft vascularization, stromal graft rejection, and recurrence of herpetic keratitis. Increased deep anterior lamellar keratoplasty graft survival is mainly built upon optimization of the ocular surface to provide a hospitable environment for the graft. Any predisposing factors for graft epithelial abnormalities, corneal neovascularization, and preexisting vernal keratoconjunctivitis should be identified and treated preoperatively. Prompt recognition and appropriate treatment of interface-related complications and stromal graft rejection usually result in good anatomic outcomes, with no detrimental effects on vision.

Recurrent oral ulceration: Etiology, classification, management, and diagnostic algorithm

Recurrent oral ulcerations are manifestations of a heterogeneous set of both general and more-or-less specific oral diseases due to numerous potential etiologies, including, but not limited to, infections, medications, autoimmune disease, and other systemic disease. This review discusses the pathogenesis, clinical presentation, diagnosis, and management of the common causes of recurrent oral ulceration. The following types/etiologies of recurrent oral ulceration are covered: traumatic ulceration, chemical ulceration, recurrent aphthous stomatitis, medication-related ulceration, infectious ulceration, mucocutaneous disease, and autoimmune/systemic disease. A diagnostic algorithm for recurrent oral ulceration is also presented.

Eye Symptom Questionnaire to Evaluate Anterior Eye Health

OBJECTIVES

Ophthalmologists assess eye complaints with a careful history and eye examination; however, other types of physicians have limited tools to evaluate anterior segment (AS) eye diseases. We identified the eye symptom questions that providers should ask to help determine the presence and urgency of AS eye diseases.

METHODS

Persons with and without AS disease completed a self-report eye symptom questionnaire (ESQ) based on the National Institutes of Health Toolbox symptom items in an academic center's corneal and comprehensive eye clinics. Gold standard ophthalmic examination determined the presence and urgency of AS disease. The association between reported symptom severity and the probability of AS disease, or urgent AS disease, was evaluated using logistic regression models, and sensitivity and specificity of the ESQ were also calculated.

RESULTS

A total of 324 eyes of 162 subjects were included in the study. Of these, AS disease was present in 255 eyes (79%); of which, 111 eyes showed urgent disease. Increasing symptom severity for eye pain (odds ratio [OR]=2.58; P<0.001), glare (OR=2.61; P=0.001), and blurry vision (OR=1.98; P<0.001) were associated with increased odds of AS disease. Increasing symptom severity for eye pain (OR=2.02; P<0.001), eye redness (OR=1.69; P=0.02), and blurry vision (OR=1.41, P=0.01) were associated with increased odds of urgent AS disease. For the primary analysis with mild symptoms considered relevant, the sensitivity of the ESQ to detect AS disease was 83% and to detect urgent AS disease was 92%.

CONCLUSION

Symptoms of eye pain, glare, redness, and blurry vision indicate the presence and urgency of AS disease.

Epithelial Keratitis After Cataract Surgery

PURPOSE

To evaluate the incidence, related perioperative factors, clinical characteristics, and possible etiologies of epithelial keratitis after cataract surgery.

METHODS

A retrospective chart review of 666 eyes in 666 patients who underwent cataract surgery was performed to evaluate the incidence of epithelial keratitis and related factors in the postoperative period.

RESULTS

Postoperative epithelial keratitis developed in 15 eyes. Eleven of the 15 eyes were diagnosed with herpes simplex keratitis (HSK); 10 of the 11 eyes were diagnosed by polymerase chain reaction, and the remaining 1 eye by clinical diagnosis. All patients diagnosed with HSK had no previous clinical history of the infection before undergoing cataract surgery. Initially, the diagnosis of all 15 eyes was toxic keratitis, but the final diagnosis of 11 of the initial 15 was found to be epithelial herpes keratitis. The incision location was shown to be related to the occurrence of HSK in our study (P < 0.05).

CONCLUSIONS

HSK epithelial keratitis after cataract surgery is a relatively uncommon complication and can be misdiagnosed in its early disease course because of its relative rarity. This study explores the possibility that the temporal corneal penetrating incisional approach used in routine cataract surgery interrupts the corneal nerves and subsequently can trigger reactivation of HSK.

Application of our understanding of pathogenesis of herpetic stromal keratitis for novel therapy

HSV-1 ocular infection can cause herpes stromal keratitis (SK), an immunopathological lesion. Frequent recurrences can lead to progressive corneal scaring which can result in vision impairment if left untreated. Currently, the acute and epithelial forms of SK are usually controlled using anti-viral drugs. However, chronic forms of SK which are inflammatory in nature, require the addition of a topical corticosteroid to the anti-viral treatment regimen. In this review, we highlight the essential events involved in SK pathogenesis which can be targeted for improved therapy. We also examine some approaches which can be combined with the current treatments to effectively control SK.

Neonatal testicular cell transplantation restores murine spermatogenesis damaged in the course of herpes simplex virus-induced orchitis

Genital tract infection and inflammation may affect male fertility, causing germ and Sertoli cell loss. We determined if testicular cell transplantation is effective at repairing testicular injury induced by herpes simplex virus (HSV) orchitis. ROSA26 mice were used as donors and the recipients were C57BL/6 mice after HSV testicular inoculation; some of the recipients were treated with the antiviral drug acyclovir (ACV). ACV reduced the amount of HSV antigen in testes on Day 3 after transplantation and enhanced the efficacy of transplantation at Day 30. In recipient testes, donor Sertoli cells formed new seminiferous tubules; significantly more new tubules were observed in the testes of ACV-treated mice compared with mice not treated with ACV (17.8% vs 3.6%). Over half (50.4%) of new tubules in ACV-treated testes contained germ cells and round spermatids were detected in 14.2% of new tubules compared with 15.9% and 5.3% in testes not treated with ACV, respectively. At Day 150 the seminiferous epithelium was completely recovered in some donor tubules and elongated spermatids were observed inside it. Thus, our findings reveal the effectiveness of the combination of antiviral therapy with neonatal testis-cell transplantation for the restoration of spermatogenesis damaged by viral infection.

Reversible nerve damage and corneal pathology in murine herpes simplex stromal keratitis

Herpes simplex virus type 1 (HSV-1) shedding from sensory neurons can trigger recurrent bouts of herpes stromal keratitis (HSK), an inflammatory response that leads to progressive corneal scarring and blindness. A mouse model of HSK is often used to delineate immunopathogenic mechanisms and bears many of the characteristics of human disease, but it tends to be more chronic and severe than human HSK. Loss of blink reflex (BR) in human HSK is common and due to a dramatic retraction of corneal sensory nerve termini in the epithelium and the nerve plexus at the epithelial/stromal interface. However, the relationship between loss of BR due to nerve damage and corneal pathology associated with HSK remains largely unexplored. Here, we show a similar retraction of corneal nerves in mice with HSK. Indeed, we show that much of the HSK-associated corneal inflammation in mice is actually attributable to damage to the corneal nerves and accompanying loss of BR and can be prevented or ameliorated by tarsorrhaphy (suturing eyelids closed), a clinical procedure commonly used to prevent corneal exposure and desiccation. In addition, we show that HSK-associated nerve retraction, loss of BR, and severe pathology all are reversible and regulated by CD4(+) T cells. Thus, defining immunopathogenic mechanisms of HSK in the mouse model will necessitate distinguishing mechanisms associated with the immunopathologic response to the virus from those associated with loss of corneal sensation. Based on our findings, investigation of a possible contribution of nerve damage and BR loss to human HSK also appears warranted. Importance: HSK in humans is a potentially blinding disease characterized by recurrent inflammation and progressive scarring triggered by viral release from corneal nerves. Corneal nerve damage is a known component of HSK, but the causes and consequences of HSK-associated nerve damage remain obscure. We show that desiccation of the corneal surface due to nerve damage and associated loss of BR severely exacerbates and prolongs inflammation-induced pathology in mice. Preventing corneal desiccation results in a milder and more transient HSK with variable scarring that mirrors HSK seen in most humans. We further show that nerve damage is reversible and regulated by CD4(+) T cells. Thus, we provide a mouse model that more closely resembles typical human HSK and suggest nerve damage is an important but largely overlooked factor in human disease.

Functional hierarchy of herpes simplex virus type-1 membrane proteins in corneal infection and virus transmission to ganglionic neurons

PURPOSE

To determine the relative importance of viral glycoproteins gK, gM, gE and the membrane protein UL11 in infection of mouse corneas and ganglionic neurons.

METHODS

Mouse eyes were scarified and infected with herpes simplex virus (HSV)-1(F), gE-null, gM-null, gK-null, or UL11-null viruses. Clinical signs of ocular disease were monitored daily. Virus shedding was determined at 24, 48 and 72 h post infection. Viral DNA within trigeminal ganglia (TG) was quantified by quantitative PCR at 30 d post infection.

RESULTS

The gE-null virus replicated as efficiently as the parental virus and formed viral plaques approximately half-the-size in comparison with the HSV-1(F) wild-type virus. The UL11-null and gM-null viruses replicated approximately one log less efficiently than the wild-type virus, and formed plaques that were on average one-third the size and one-half the size of the wild-type virus, respectively. The gK-null virus replicated more than 3-logs less efficiently than the wild-type virus and formed very small plaques (5-10 cells). Mice infected with the wild-type virus exhibited mild clinical ocular symptoms, while mice infected with the mutant viruses did not show any significant ocular changes. The wild-type virus produced the highest virus shedding post infection followed by the gM-null, gE-null and UL11-null viruses, while no gK-null virus was detected at any time point. All TG collected from mice infected with the wild-type virus and 6-of-10 of TG retrieved from mice infected with the UL11-null virus contained high numbers of viral genomes. The gE-null and gM-null-infected ganglia contained moderate-to-low number of viral genomes in 4-of-10 and 2-of-10 mice, respectively. No viral genomes were detected in ganglionic tissues obtained from gK-null eye infections.

CONCLUSIONS

The results show that gK plays the most important role among gM, gE and UL11 in corneal and ganglionic infection in the mouse eye model.

A replication competent HSV-1(McKrae) with a mutation in the amino-terminus of glycoprotein K (gK) is unable to infect mouse trigeminal ganglia after cornea infection

PURPOSE

To determine the role of the amino terminus of herpes simplex virus-1 (HSV-1) glycoprotein K (gK) in corneal infection, neuroinvasion, and establishment of virus latency in trigeminal ganglia of mice.

METHODS

The recombinant virus HSV-1 (McKΔgK31-68) was constructed by engineering gK genes encoding gK lacking 38 amino acids immediately after the gK signal sequence. A rescued virus was also produced. Mouse eyes were scarified and infected with 10(5) plaque forming units (PFU) in each eye. Clinical signs of ocular disease were monitored daily. Thirty days postinfection trigeminal ganglia were collected and processed for quantitative PCR (qPCR) analysis of viral DNA and recovery of infectious virions by cell culture of ganglionic tissues.

RESULTS

Deletion of the amino terminus of gK encoded by the McKΔgK31-68 mutant virus did not substantially affect its replication kinetics on African green monkey kidney cells (Vero), while it reduced cell-to-cell spread. McK viral infection of scarified mouse corneas with 10(5) PFU produced severe ocular disease. In contrast, McKΔgK31-68 viral infection with 10(5) PFU produced no significant ocular disease symptoms. All ganglia from mice infected with the McK virus produced high numbers of infectious virions upon explant culture in Vero cells, in agreement with qPCR results detecting high number of HSV-1 viral DNA in ganglionic tissues. In contrast, qPCR failed to detect any viral genomes in McKΔgK31-68 ganglia, while two of the ten ganglia revealed the presence of low numbers of infectious virions upon explant culture in Vero cells.

CONCLUSIONS

The results show that the amino terminus of gK is essential for neuroinvasiveness and acute herpes keratitis in the mouse eye model. It is likely that gK is involved in efficient infection of axonal termini, since mouse eye scarification provided a direct access to the high density of neuronal axons innervating mouse corneas.

Effectiveness and safety of 0.15% ganciclovir in situ ophthalmic gel for herpes simplex keratitis - a multicenter, randomized, investigator-masked, parallel group study in Chinese patients

Objectives

Parallel comparison with 0.15% ganciclovir (GCV) ophthalmic gel to evaluate the effectiveness and safety of 0.15% GCV in situ ophthalmic gel for the treatment of herpes simplex keratitis (HSK).

Methods

This was a multicenter, randomized, investigator-masked, parallel group study. HSK patients were randomly divided into two groups, with the corresponding treatment of 0.15% GCV ophthalmic gel or 0.15% GCV in situ ophthalmic gel. Symptoms and signs were observed before administration, and 3 (±1), 7 (±1), 14 (±2), and 21 (±3) days after the administration. The clinical effective rate was considered as the primary outcome. The safety profile was evaluated by AEs, visual acuity, and ocular tolerance.

Results

The clinical effective rate in the per-protocol (PP) dataset for the treatment group and the control group were 95.10% and 93.00%, respectively (P = 0.5282). The noninferiority test showed significant differences (P = 0.000305, P < 0.025), indicating that the tested drug was noninferior to the control. Patients in the PP dataset of both groups experienced decreases in the total scores of clinical indicators. Ocular AEs were few but similar between the two groups. There were no significant differences between patients’ visions between the two groups before and after administration in the safety analysis set. In terms of drug tolerance, the rates of patients without transient blurred vision during all the visits in the treatment group were higher than those for the control group (P < 0.05). During the third and fourth visits, the rates of patients with eye itching were 4.08% and 1.22% in the treatment group, and 13.59% and 8.14% in the control group, respectively (P < 0.05). During the second visit, the rates of patients with eye irritation were 14.42% in the treatment group and 25.71% in the control group (P < 0.05).

Conclusion

The 0.15% GCV in situ ophthalmic gel was effective and safe for the treatment of HSK, and was not inferior to 0.15% GCV ophthalmic gel. The 0.15% GCV in situ ophthalmic gel presented superior ocular tolerance.

Bilateral herpetic keratitis presenting with unilateral neurotrophic keratitis in pemphigus foliaceus: a case report

INTRODUCTION

We report a case of bilateral herpetic keratitis developing after rapid oral corticosteroid tapering in a patient with pemphigus foliaceus, which was followed by unilateral neurotrophic keratitis that was treated with amniotic membrane transplantation.

CASE PRESENTATION

A 71-year-old Korean man developed bilateral herpetic keratitis one week after rapid tapering of systemic corticosteroid. He had been on high-dose oral corticosteroid and azathioprine therapy for six months for treatment of pemphigus foliaceus. Topical acyclovir ointment was prescribed. A week later, our patient's right eye had healed, but his left eye showed increased stromal edema with enlarged epithelial defects. He was prescribed oral acyclovir with topical broad-spectrum antibiotics applied to his left eye. The stromal edema cleared within a week but the epithelial defect remained unchanged. An amniotic membrane transplantation was performed on our patient's left eye, and his epithelial defect had totally healed three weeks later.

CONCLUSIONS

Patients with autoimmune disease or who are on immunosuppressive therapy have a higher chance of developing bilateral herpetic keratitis. Although rare, the condition may be followed by unilateral neurotrophic keratitis. Rapid corticosteroid tapering may act as a triggering factor for viral infection or reactivation of herpes.

Linear Corneal Epithelial Keratitis with a Horseshoe Pattern

PURPOSE

To report the treatment and follow-up of a linear epithelial keratitis with a horseshoe pattern.

METHODS

A 21-year-old Turkish soldier, who presented with epithelial keratitis with a horseshoe pattern that did not respond to immunosuppressive and multiple anti-microbial treatment, was studied clinically.

RESULTS

No microorganism was identified with different stains, cultures, and herpes simplex virus-polymerase chain reaction. The impression cytology revealed prominent polymorphonuclear leukocyte infiltration at the keratitis line. The keratitis did not respond to different antimicrobial treatment or local and systemic corticosteroids. After a fourth scraping was perfomed deeply with a disc-knife, the lesion healed and did not recur in six months.

CONCLUSION

Linear epitheliitis of cornea with a horseshoe pattern was not found to be associated with any microorganism or systemic disease.

Patterns of rejection after deep lamellar keratoplasty

PURPOSE

To describe 7 patients with keratoconus who underwent graft rejection after deep lamellar keratoplasty (DLK).

DESIGN

Retrospective case series and literature review.

PARTICIPANTS

Seven patients who underwent DLK for keratoconus between 1997 and 2001. These cases were compared with a previously reported case series of DLK for keratoconus between 1994 and 2001.

METHODS

The clinical records of patients with rejection after DLK for keratoconus were examined to obtain details of the surgery, the interval to the rejection episode and its treatment, best-corrected visual acuity (BCVA), and presence of potential risk factors for rejection. The clinical features and course of rejection were compared with reports of corneal graft rejection in the literature. Patient characteristics were compared with the reported series of patients who had DLK for keratoconus.

MAIN OUTCOME MEASURES

Final BCVA and number, type, and features of rejection episodes.

RESULTS

The mean age was 28 years, with a median follow-up of 40 months after DLK. Rejection occurred between 3 and 41 months postoperatively. Four patients were atopic, 4 had a penetrating keratoplasty in the fellow eye, and 1 had deep stromal vessels in the host cornea. Isolated epithelial rejection occurred in 1 patient and stromal rejection in 3 cases, and there were 3 cases of mixed stromal and epithelial rejection. Topical steroid therapy led to reversal of rejection in 5 cases. Two patients had progressive vascularization with graft failure and poor vision. The median final BCVA was 6/9 (range, 6/6-6/36).

CONCLUSIONS

Deep lamellar keratoplasty avoids the risk of endothelial rejection, but epithelial or stromal rejection may still occur. Recognition and appropriate treatment are needed to prevent graft failure with subsequent visual loss.

Enterovirus 70 binds to different glycoconjugates containing alpha2,3-linked sialic acid on different cell lines

Enterovirus 70 (EV70), the causative agent of acute hemorrhagic conjunctivitis, exhibits a restricted tropism for conjunctival and corneal cells in vivo but infects a wide spectrum of mammalian cells in culture. Previously, we demonstrated that human CD55 is a receptor for EV70 on HeLa cells but that EV70 also binds to sialic acid-containing receptors on a variety of other human cell lines. Virus recognition of sialic acid attached to underlying glycans by a particular glycosidic linkage may contribute to host range, tissue tropism, and pathogenesis. Therefore, we tested the possibility that EV70 binds to alpha2,3-linked sialic acid, like other viruses associated with ocular infections. Through the use of linkage-specific sialidases, sialyltransferases, and lectins, we show that EV70 recognizes alpha2,3-linked sialic acid on human corneal epithelial cells and on U-937 cells. Virus attachment to both cell lines is CD55 independent and sensitive to benzyl N-acetyl-alpha-D-galactosaminide, an inhibitor of O-linked glycosylation. Virus binding to corneal cells, but not U-937 cells, is inhibited by proteinase K, but not by phosphatidylinositol-specific phospholipase C treatment. These results are consistent with the idea that a major EV70 receptor on corneal epithelial cells is an O-glycosylated, non-glycosyl phosphatidylinositol-anchored membrane glycoprotein containing alpha2,3-linked sialic acid, while sialylated receptors on U-937 cells are not proteinaceous.

Early events in HSV keratitis--setting the stage for a blinding disease

The last decade has seen herpes simplex virus (HSV)-induced stromal keratitis (SK) research shift from being a topic only of interest to vision researchers to one that fascinates the general field of inflammatory disease. Studies on experimental mouse lesions have uncovered several fundamental processes that explain lesion development. In this model, the chronic immuno-inflammatory lesions are mainly orchestrated by CD4+ T cells, but multiple early events occur that set the stage for the subsequent pathology. These include virus replication, the production of key cytokines and chemokines, neovascularization of the avascular cornea and the influx of certain inflammatory cell types. Many of these early events are subject to modulation, providing an approach to controlling this important cause of human blindness. We also comment on events ongoing during chronic SK, debating whether or not these represent virus-induced or autoimmune lesions.

Counteracting corneal immunoinflammatory lesion with interleukin-1 receptor antagonist protein

Herpetic stromal keratitis (HSK) is a T cell-orchestrated, immunoinflammatory lesion that results from corneal Herpes simplex virus infection. Previous reports indicate an essential role for proinflammatory cytokine interleukin (IL)-1 in HSK pathogenesis. The present study evaluates the efficacy of IL-1 receptor antagonist (IL-1 ra) protein in the management of HSK. Mice receiving IL-1 ra had diminished disease severity. The administration of IL-1 ra was shown to reduce the influx into the cornea of cells of the innate and adaptive immune response. In addition, the treatment diminished corneal vascular endothelial growth factor levels, resulting in reduced angiogenic response. Our results show the importance of targeting early proinflammatory molecules such as IL-1 to counteract HSK and advocate IL-1 ra as an effective agent to achieve this.