Histopathology of herpes simplex virus keratouveitis

Role of Herpes Simplex Envelope Glycoprotein B and Toll-Like Receptor 2 in Ocular Inflammation: An ex vivo Organotypic Rabbit Corneal Model

It has been recently reported, using in vitro studies, that the herpes simplex virus 1 (HSV-1) encoded envelope glycoprotein B (gB1) interacts with cell surface toll-like receptor 2 (TLR2) and induces the secretion of interleukin-8 (IL8), a representative marker of inflammatory cytokine activation. The purpose of this study is to investigate the role of gB1 in activating host inflammatory responses by using a secreted form of gB1 (gB1s) and an ex vivo organotypic rabbit corneal model. Abraded corneas exposed to gB1s alone or to the recombinant protein mixed with anti gB polyclonal antibody were cultured in an air-liquid interface. The corneas exposed to gB1s show the appearance of mydriasis and high levels of TLR2 and IL-8 mRNAs transcripts were detected in the superficial layer of corneal epithelial cells. Histological stain and immunohistochemical analyses revealed morphological changes in the epithelium of the treated corneas and variations in expression and localization of TLR2. Collectively these findings provide new insight into the pathogenesis of HSV-1 ocular infection by demonstrating the leading role of gB in activating an inflammatory response and in the appearance of mydriasis, a sign of HSV-1 anterior uveitis.

A synthetic glycosaminoglycan mimetic blocks HSV-1 infection in human iris stromal cells

Herpes simplex virus type-1 (HSV-1) is a significant pathogen that affects vision by targeting multiple regions in the human eye including iris. Using a focused library of synthetic non-saccharide glycosaminoglycan mimetics (NSGMs), we identified sulfated pentagalloylglucoside (SPGG) as a potent inhibitor of HSV-1 entry and cell-to-cell spread in the primary cultures of human iris stromal (HIS) cells isolated from eye donors. Using in vitro β-galactosidase reporter assay and plaque reduction assay, SPGG was found to inhibit HSV-1 entry in a dosage-dependent manner (IC₅₀ ∼6.0 μM). Interestingly, a pronounced inhibition in HSV-1 entry and spread was observed in HIS cells, or a cell line expressing specific gD-receptor, when virions were pre-treated with mimetics suggesting a possible interaction between SPGG and the HSV-1 glycoprotein. To examine the significance of gD-SPGG interaction, HIS cells were pretreated with SPGG, which showed a significant reduction in gD binding. Taken together, our results provide strong evidence of SPGG being a novel viral entry inhibitor against ocular HSV infection.

Presumed Herpetic Anterior Uveitis: A Study with Retrospective Analysis of 79 Cases

Purpose

To describe the clinical features, visual outcome, medical treatment, and complications of presumed herpetic anterior uveitis.

Methods

We retrospectively analyzed the clinical data related to 79 eyes of 77 patients with presumed herpetic anterior uveitis seen at the Uveitis Unit of the Ulucanlar Eye Training and Research Hospital from 1996 to 2011. Age at onset of disease, sex, follow-up duration, existence of corneal involvement, posterior synechiae, distorted pupil, iris atrophy, characteristic of keratic precipitates, elevated intraocular pressure (IOP), medical treatment, recurrence rate, complications, visual acuities (VA), and surgery for complications were recorded. The complication rates in patients with and without corneal involvement were compared.

Results

There were 38 (49.4%) female and 39 (50.6%) male patients. The mean age at presentation was 48.5 ± 14.8 (20–82) years. The follow-up period was 26.5 (2–127) months. Two patients had bilateral involvement. Ocular findings were a corneal scar or active keratitis in 37 (46.8%) eyes, secondary glaucoma in 14 (17.7%), iris atrophy in 39 (49.4%), distorted pupil in 16 (20.3%), posterior synechiae in 23 (29.1%), and granulomatous anterior uveitis in 30 (40%) eyes. Eight (10.1%) eyes had a posterior subcapsular cataract. Glaucoma surgery was required for uncontrolled IOP with maximum medical treatment in 2 (2.4%) eyes. Long-term oral acyclovir was used in 9 (11.3%) patients. Final VA was ≤ 0.1 in 8 (10.1%) eyes; of these, 6 had either corneal scarring or cataract and 2 preexisting amblyopia.

Conclusions

Presumed herpetic anterior uveitis with or without keratitis has characteristic clinical findings that enable the diagnosis. Long-term prophylactic antiviral therapy should be considered especially in patients <50 years old.

Susceptibility of human iris stromal cells to herpes simplex virus 1 entry

Ocular herpes simplex virus 1 (HSV-1) infection can lead to multiple complications, including iritis, an inflammation of the iris. Here, we use human iris stroma cells as a novel in vitro model to demonstrate HSV-1 entry and the inflammatory mediators that can damage the iris. The upregulated cytokines observed in this study provide a new understanding of the intrinsic immune mechanisms that can contribute to the onset of iritis.

Vasculitis and systemic infections

PURPOSE OF REVIEW

In recent years, many investigators have focused on potential associations between infections and vascular inflammation. We review the principal pathogenic mechanisms that have been implicated for possible roles in the vascular inflammation initiated by infectious agents. We also summarize the most important literature related to this topic.

RECENT FINDINGS

A novel theory known as autoantigen complementarity suggests that an infectious agent could trigger antineutrophil cytoplasmic antibody-associated vasculitis. Several recent studies investigating the presence of parvovirus B19 and herpesviruses in temporal arteries with giant cell arteritis have yielded contradictory results. A recent study has identified higher frequency of a novel human virus, the 'New Haven coronavirus', in respiratory secretions of children with Kawasaki disease. Many case reports have suggested potential relationships between human pathogens and vasculitis.

SUMMARY

There remains considerable interest in the possibilities of primary vasculitic syndromes caused in some fashion by infection. With the exception of a few well sustained associations - for example hepatitis B or C with known vasculitic syndromes - most of the purported links between microbial agents and primary vasculitides remain speculative.

Progressive subretinal fibrosis and blindness associated with multifocal granulomatous chorioretinitis: A variant of sympathetic ophthalmia

OBJECTIVE

To report a case of bilateral progressive subretinal fibrosis and blindness with multifocal granulomatous chorioretinitis occurring after intraocular surgery. We propose that this is a variant of sympathetic ophthalmia.

DESIGN

Clinicopathologic case report.

METHODS

The left enucleated globe was examined by histopathologic methods. The patient's sera were subjected to immunohistochemical studies against retinal antigens, and collagen 2 types in areas of fibrosis were identified. Polymerase chain reaction was used to test for herpes virus DNA in microdissected, formalin-fixed, paraffin-embedded tissue.

RESULTS

The enucleated globe demonstrated histopathologic features similar to an entity previously described as progressive subretinal fibrosis with multifocal granulomatous chorioretinitis. The patient's sera demonstrated antibodies directed against retinal photoreceptors and pigment epithelium. Polymerase chain reaction for herpes virus was negative. Immunohistochemical studies demonstrated types III, IV, V, and VI collagen in areas of fibrosis.

CONCLUSIONS

The clinical history along with the histopathologic and immunohistochemical findings suggest that progressive subretinal fibrosis with multifocal granulomatous chorioretinitis may represent a variant of sympathetic ophthalmia and that retinal autoimmunity may play a role in its pathogenesis.

Visual outcome in herpes simplex virus and varicella zoster virus uveitis: a clinical evaluation and comparison

PURPOSE

To compare clinical characteristics and outcomes in patients with uveitis caused by herpes simplex virus (HSV) and varicella zoster virus (VZV).

DESIGN

Retrospective comparative study.

PARTICIPANTS

Forty patients with HSV uveitis and 24 patients with VZV uveitis.

METHODS

A retrospective study of 40 patients with HSV and 24 patients with VZV uveitis was performed. The patients were followed between May 1987 and September 1999 (median follow-up time, 46 months). The diagnosis of HSV uveitis was made clinically and serologically, and the diagnosis of VZV uveitis was made clinically.

MAIN OUTCOME MEASURES

Clinical presentation of the disease, ocular complications, visual acuity, surgical and medical treatments needed.

RESULTS

Both populations were comparable for gender and age at disease onset. The course of the disease tended to be remitting and recurrent in HSV patients and chronic in VZV patients (P = 0.046). The most frequent ocular complication in both groups was secondary glaucoma (54% HSV, 38% VZV). Twenty-five percent of VZV patients developed posterior pole complications (cystoid macular edema, epiretinal membrane, papillitis, retinal fibrosis, and detachment) compared with 8% of HSV patients (P = 0.069). Treatment modalities selected were generally similar in the two groups, although periocular and systemic steroids were required more frequently in HSV patients (60% versus 25%; P = 0.01). Surgical procedures were required with similar frequency in both populations. The percentage of eyes that were legally blind at end of follow-up was also comparable (HSV, 20%; VZV, 21%). The visual outcome was similar in the studied populations.

CONCLUSIONS

This study represents the only direct comparison of HSV and VZV uveitis patients reported in the literature. HSV patients were more likely to be treated with periocular and systemic steroids, and VZV patients were more likely to develop posterior pole complications (a finding of borderline significance). Other parameters evaluated in this study were not statistically different in the two patient groups.

Recurrence rate of herpetic uveitis in patients on long-term oral acyclovir

We examined the recurrence rate of herpetic uveitis (HU) in 13 patients (group A) treated prophylactically with long-term systemic acyclovir (600-800 mg/day) and compared it with that of 7 patients with no prophylactic therapy (group B). HU was diagnosed on the basis of a history of dendritic or disciform keratitis accompanied by iridocyclitis and iris atrophy. The study population consisted of 12 men and 8 women with a mean age at onset of uveitis of 52.9 years (range 19-78 years). All patients were followed for at least 8 months. The mean follow-up time of patients on long-term oral acyclovir was 26.0 months. In this group, only one patient experienced a single recurrent episode of uveitis while on 600-800 mg/day of acyclovir therapy; two additional patients had recurrence of HU within 16.2 months after the acyclovir dose was tapered below 600 mg/day. In striking contrast, 16 recurrences occurred in the 7 patients of group B (p < 0.05). Of these, the initial recurrence occurred within an average of 4.3 months following cessation of therapy. There was a significant difference (p < 0.05) in the mean recurrence-free interval between patients in group A (24.6 months) and those in group B (3.4 months). Herpetic uveitis is a serious ocular disease in which recurrence of inflammation results in severe ocular complications. The long-term use of oral acyclovir may be of benefit in the prevention of recurrences, and hence may reduce the blinding complications of this disease. Efforts at completing a randomized, placebo-controlled trial on this matter by the Herpes Epithelial Disease Study Group were unsuccessful due to insufficient patient recruitment.

Intercellular Adhesion Molecule-1 (ICAM-1) and HLA-DR Antigens in Herpes Keratitis

PURPOSE

Intercellular adhesion molecule-1 (ICAM-1) is a cell surface glycoprotein that binds leukocyte function antigen-1 receptor on leukocytes, thereby regulating leukocyte trafficking and function at sites of inflammation. Recently, the authors demonstrated ICAM-1 in human corneas exposed to proinflammatory cytokines, but ICAM-1 has not been reported in corneal disease. In this study, the presence of ICAM-1 in human disciform herpes simplex virus (HSV) keratitis is investigated.

METHODS

Immunohistochemistry was performed for ICAM-1 on 4 keratoplasty specimens from patients with corneal scarring due to disciform HSV keratitis and 1 corneoscleral biopsy of a patient with active HSV keratoscleritis using specific, characterized monoclonal antibody to ICAM-1. Negative immunohistochemical controls included monoclonal antibodies to other vascular endothelial adhesion molecules or mouse serum.

RESULTS

All 5 specimens demonstrated intense ICAM-1 immunoreactivity of keratinocytes, stromal keratocytes, and endothelial cells, predominantly in regions of leukocytic infiltration. Diffuse, intense HLA-DR positivity was detected throughout the corneas. The specimens failed to react with control antibodies.

CONCLUSION

These results are the first to demonstrate ICAM-1 in human corneal disease and suggest important roles for ICAM-1 and HLA-DR co-expression in generating immune responses in HSV keratitis. Increased ICAM-1 expression in regions of leukocytic infiltration may regulate leukocyte-corneal cell binding, thereby promoting immune responses and damage by activated leukocytes.

Herpes simplex keratitis: role of viral infection versus immune response

The cumulative clinical and experimental data regarding the role of viral infection versus the immune response in the pathogenesis of herpes simplex stromal keratitis and central disciform endotheliitis are discussed. Ultrastructural and viral isolation studies have been performed in only a limited number of cases of human stromal keratitis and disciform endotheliitis. Virus has been isolated from the minority of corneas cultured, whereas viral particles have been demonstrated in selected cases of stromal keratitis, most of which had been treated with steroids at some point in time. The possibility of corneal latency in cases of quiescent herpetic stromal keratitis will require further systematic study. Review of the experimental and clinical findings suggests a dialectical role of the immune response in limiting viral infection, while contributing to corneal opacification and scar formation.

Anterior segment ischemia in chronic herpes simplex keratouveitis

Six patients with chronic herpes simplex keratouveitis developed a rapidly progressive ocular inflammation unresponsive to corticosteroid and antiviral therapy. Severe secondary glaucoma unresponsive to maximum medical therapy ensued and was treated by cyclocryotherapy in five patients. Ocular ischemia with secondary corneal and scleral calcification subsequently developed in all six patients. All had also received prolonged topical therapy with topical antiviral agents, corticosteroids, beta adrenergic blockers and epinephrine compounds. Three eyes eventually required enucleation for the relief of pain; one stabilized, and two others became phthisical. One of the phthisical eyes developed a secondary fungal endophthalmitis. Histopathologic examination of the three enucleated globes revealed extensive corneal, scleral and conjunctival calcification, secondary angle closure, iris and ciliary body necrosis, focal choroiditis, retinal necrosis and atrophy. The syndrome recognized in these patients appears to be a rare but devastating complication of herpes simplex keratouveitis, possibly exacerbated by the application of cyclocryotherapy and other factors.

Herpes simplex stromal and endothelial keratitis. Granulomatous cell reactions at the level of Descemet's membrane, the stroma, and Bowman's layer

Fifty-three (25%) of 215 keratectomy specimens of patients with herpes simplex stromal keratitis displayed granulomatous reactions at the level of Descemet's membrane (50/53), midstroma (13/53), and Bowman's layer (5/53). Using an immunoperoxidase technique, herpes simplex virus (HSV) antigens were detected in keratocytes, endothelial cells, and foci of epithelioid histiocytes and multinucleated giant cells around Descemet's membrane. Both granulomatous reactions and HSV antigens were identified significantly more often in specimens with ulcerative necrotizing stromal keratitis than in those from patients with stromal scarring or nonulcerative nonnecrotizing keratitis (P less than 0.00001 and P less than 0.005, respectively). Herpes simplex virus antigens also were present in endothelial cells adjacent to foci of granulomatous reactions around Descemet's membrane in association with disciform stromal scarring. To our knowledge, this is the first demonstration of HSV antigens in human corneal endothelial cells and in the granulomatous reactions at the level of Descemet's membrane.