Therapeutic interventions for herpes simplex virus epithelial keratitis

Development of lacrimal gland inflammation in the mouse model of herpes stromal keratitis

Herpes stromal keratitis (HSK) is a chronic immunoinflammatory condition which develops in response to recurrent herpes simplex virus-1 (HSV-1) infection of the cornea. Patients with HSK often demonstrate the concurrence of corneal desiccation and the loss of blink reflex. However, the relationship between severity of HSK, level of basal tears and inflammation of the lacrimal gland is mostly unexplored. In this study, we compared these variables in extraorbital lacrimal gland (EoLG) after corneal HSV-1 infection in the C57BL/6J mouse model. Our results showed a significant reduction in the volume of tears in infected eyes during the development of HSK. Extensive architectural damage to EoLG, presumably caused by a massive influx of interferon-gamma secreting T cells, was observed during clinical disease period of HSK. A positive correlation between the decrease in tear volume, severity of HSK and the damage to EoLG were evident in infected mice. The presence of infectious virus measured in EoLG during pre-clinical, but not clinical disease period of HSK, suggested that viral cytopathic effects are not the major contributors of extensive damage seen in EoLG. Furthermore, topical administration of lacritin peptide delayed but did not prevent the decrease in tears in HSV-1 infected mice, and had no significant effect in either reducing the severity of HSK or T cell infiltration in EoLG of infected mice. Together, our results showed an interplay between the severity of HSK, inflammation of EoLG, and the reduced level of tears after corneal HSV-1 infection.

A systematic review and meta-analysis to compare the efficacy of acyclovir 3% ophthalmic ointment to idoxuridine in curing herpetic keratitis by Day 7 of treatment

BACKGROUND

This objective of the review and analysis is to demonstrate that acyclovir (ACV) 3% ophthalmic ointment is superior to idoxuridine (IDU) in treating herpetic keratitis (HK) presenting as dendritic and geographic ulcer sub-types.

METHODS

DATA SOURCES

Publications in human subjects were identified by searching the Ovid MEDLINE database through April 2011, combining medical subject headings (MESH) "Keratitis, Herpetic/" AND "Acyclovir/" limiting by the key words "topical" OR "ointment" and also restricted to MESH "Administration, Topical/" OR "Ointments/". The results were cross checked with the references used in the Cochrane Database Syst Rev. 1:1-134, 2009 and GlaxoSmithKline clinical documents related to acyclovir.

STUDY SELECTION

Randomized, double-masked studies in subjects diagnosed with HK with head to head comparator arms of ACV ophthalmic ointment and topical IDU that had actual or calculable healing rates at Day seven.

DATA EXTRACTION

Data independently extracted from identified articles by two authors of this manuscript.

DATA SYNTHESIS

Data from seven randomized, controlled trials (RCT) evaluating 432 subjects that met inclusion criteria (214 were treated with ACV and 218 were treated with IDU) and had Day seven healing rates calculable. All sub-classified lesions were identified as either dendritic ulcers (n = 185) or geographic ulcers (n = 35). The Cochran-Mantel-Haenszel (CMH) method in Biometrics 10:417-51, 1954 and JNCI 22:719-48, 1959, controlling for study, was performed as the primary analysis using SAS v9. Homogeneity was assessed using Breslow-Day-Tarone (BDT) test in IARC 1:1-32, 1980 and Biometrika 72:91-5, 1985. The analysis was performed with outliers removed to assess their impact.

RESULTS

ACV showed statistically significant greater odds of healing HK at Day seven in all subjects (Odds Ratio 3.95, 95% CI2.60, 6.00, p < 0.0001), in dendritic ulcers (Odds Ratio 4.22, 95% CI: 2.14, 8.32; p < 0.0001) and geographic ulcers (Odds Ratio 5.31, 95% CI: 1.09, 25.93; p = 0.0244).

CONCLUSION

ACV 3% ophthalmic ointment is a valuable intervention for dendritic and geographic corneal ulcers. ACV and IDU were generally well tolerated in the studies reviewed.

Antiviral treatment and other therapeutic interventions for herpes simplex virus epithelial keratitis

BACKGROUND

Eye disease due to herpes simplex virus (HSV) commonly presents as epithelial keratitis which, though usually self-limiting, may persist or progress without treatment.

OBJECTIVES

To compare the relative effectiveness of antiviral agents, interferon, and corneal debridement in the treatment of HSV epithelial keratitis.

SEARCH METHODS

We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (2014, Issue 12), PubMed (January 1946 to 31 December 2014), EMBASE (January 1980 to 31 December 2014), Latin American and Caribbean Health Sciences Literature Database (LILACS) (January 1982 to 31 December 2014), System for Information on Grey Literature in Europe (OpenGrey) (January 1995 to 31 December 2014), BIOSIS (January 1926 to 5 May 2014), Scopus (January 1966 to 31 December 2014), Japan Science and Technology Institute (J-Global) (January 1975 to 31 December 2014), China National Knowledge Infrastructure (CNKI) (January 1979 to 31 December 2014), British Library's Electronic Table of Contents (Zetoc) (January 1993 to 7 May 2014). We looked for trials listed on the the metaRegister of Controlled Trials (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov), the World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en), Chinese Clinical Trial Registry, the U.S. Food and Drug Administration (FDA) (www.fda.gov/), National Institute for Health and Clinical Excellence (NICE) (www.

EVIDENCE

nhs.uk) and the European Medicines Agency (EMA) (www.ema.europa.eu/ema/) as of 31 December 2014. There were no language or date restrictions in the search for trials. We also culled literature digests and conference proceedings as of 15 April 2014. There were no language or date restrictions in the search for trials.

SELECTION CRITERIA

Randomised and quasi-randomised trials of HSV dendritic or geographic epithelial keratitis were included that reported the proportion of eyes healed at one week, two weeks, or both after enrolment.

DATA COLLECTION AND ANALYSIS

We tabulated data on study characteristics, risk of bias, and outcomes and used direct comparisons to estimate a risk ratio (RR) and, when feasible, a hazard ratio (HR) with a 95% confidence interval (CI). Heterogeneity was assessed by an inconsistency index. A multiple treatment comparison meta-analysis consolidated direct and indirect comparisons of relative healing at 14 days.

MAIN RESULTS

One hundred thirty-seven studies involving 8333 eyes met the inclusion criteria. Placebo-controlled studies were heterogeneous in comparison with idoxuridine (RR 1.74; 95% CI 1.03 to 2.91) and few in number for vidarabine (RR 1.81; 95% CI 1.09 to 3.01), interferon (RR 1.32; 95% CI 1.06 to 1.64), and debridement. Vidarabine (RR 1.13; 95% CI 1.02 to 1.25), trifluridine (RR 1.30; 95% CI 1.18 to 1.43), acyclovir (RR 1.23; 95% CI 1.14 to 1.34), and brivudine (RR 1.34; 95% CI 1.18 to 1.51) were more effective than idoxuridine. Trifluridine (RR 1.17; 95% CI 1.03 to 1.32) and acyclovir (RR 1.11; 95% CI 1.03 to 1.19) were more effective than vidarabine. No significant differences in healing emerged among trifluridine, acyclovir, brivudine, and foscarnet although few studies compared brivudine or foscarnet with other antivirals. Any potential advantage of ganciclovir compared to acyclovir was mitigated by study heterogeneity and possible publication bias. Only one study evaluated the joint use of two topical antivirals. In a limited number of studies, oral acyclovir (RR 0.92; 95% CI 0.79 to 1.07) or the combination of oral acyclovir with a topical antiviral (RR 1.36; 95% CI 0.68 to 2.74) appeared as effective as a single topical antiviral agent. Compared to topical antiviral monotherapy, the combination of an antiviral with either interferon or debridement had inconsistent effects on expediting healing and improving outcome.

AUTHORS' CONCLUSIONS

Placebo-controlled studies of HSV epithelial keratitis are limited to superseded interventions. Trifluridine and acyclovir are more effective than idoxuridine or vidarabine and similar in therapeutic effectiveness. Brivudine and foscarnet do not substantially differ in effectiveness from trifluridine or acyclovir. Ganciclovir is at least as effective as acyclovir. The addition of interferon to a nucleoside antiviral agent and the combination of debridement with antiviral treatment need to be further assessed to substantiate any possible advantage in healing.

Ocular herpes simplex virus: how are latency, reactivation, recurrent disease and therapy interrelated?

Most humans are infected with herpes simplex virus (HSV) type 1 in early childhood and remain latently infected throughout life. While most individuals have mild or no symptoms, some will develop destructive HSV keratitis. Ocular infection with HSV-1 and its associated sequelae account for the majority of corneal blindness in industrialized nations. Neuronal latency in the peripheral ganglia is established when transcription of the viral genome is repressed (silenced) except for the latency-associated transcripts and microRNAs. The functions of latency-associated transcripts have been investigated since 1987. Roles have been suggested relating to reactivation, establishment of latency, neuronal protection, antiapoptosis, apoptosis, virulence and asymptomatic shedding. Here, we review HSV-1 latent infections, reactivation, recurrent disease and antiviral therapies for the ocular HSV diseases.

Antiviral treatment and other therapeutic interventions for herpes simplex virus epithelial keratitis

BACKGROUND

Eye disease due to herpes simplex virus (HSV) commonly presents as epithelial keratitis.

OBJECTIVES

To compare the relative effectiveness of antiviral agents, interferon, and corneal débridement in the treatment of acute HSV epithelial keratitis.

SEARCH STRATEGY

We searched CENTRAL (The Cochrane Library 2010, Issue 4), MEDLINE (January 1950 to October 2010), EMBASE (January 1980 to October 2010), Latin American and Caribbean Literature on Health Sciences (LILACS) (January 1982 to October 2010), Zetoc (British Library's Electronic Table of Contents), System for Information on Grey Literature in Europe (openSIGLE), Biosciences Information Service (BIOSIS), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov), Japan Information Center of Science and Technology (JICST-EPlus), and China Academic Journals database (CAJ) via China National Knowledge Infrastructure (CNKI) with citations confirmed using China/Asia On Demand (COAD). There were no language or date restrictions in the search for trials. All databases except CNKI and COAD were last searched on 27 October 2010, CNKI and COAD were searched on 1 April 2010. We also searched literature digests, conference proceedings and reference lists.

SELECTION CRITERIA

Of 152 eligible studies,106 comparative treatment trials involving 5872 eyes with dendritic or geographic epithelial keratitis were analysed for corneal healing over two weeks.

DATA COLLECTION AND ANALYSIS

Interventions were compared at 14 days after trial enrolment by calculating a risk ratio (RR) that was adjusted with indirect RR, assessed by an inconsistency index (I(2) ) and supplemented by a seven-day RR and a hazard ratio (HR).

MAIN RESULTS

Idoxuridine, though uncertainly better in healing outcome than control because of few trials with 14-day follow up, allowed earlier corneal re-epithelialisation. Vidarabine resulted in a significantly better outcome than placebo in one trial (RR 1.96; 95% CI 1.10 to 3.49). Compared to idoxuridine, in combined direct and indirect analyses, vidarabine (RR 1.11; 95% CI 1.03 to 1.19), trifluridine (RR 1.31; 95% CI 1.20 to 1.42), acyclovir (RR 1.23; 95% CI 1.16 to 1.31), brivudine (RR 1.38; 95% CI 1.18 to 1.61), and ganciclovir (RR 1.40; 95% CI 1.25 to 1.57) were significantly more effective. Trifluridine (RR 1.12; 95% CI 1.04 to 1.21) and acyclovir (RR 1.11; 95% CI 1.05 to 1.19) appeared more effective than vidarabine. No significant differences were found in comparisons between acyclovir, trifluridine and brivudine. The comparison of ganciclovir to acyclovir was limited by heterogeneity and possible publication bias. The joint use of two topical antivirals (RR 1.00; 95% CI 0.89 to 1.12) and the use of oral acyclovir alone (RR 0.92; 95% CI 0.79 to 1.07) or combined with a topical antiviral (RR 1.08; 95% CI 0.99 to 1.17) appeared as effective as topical antiviral therapy. Compared to antiviral monotherapy, the combination of an antiviral with interferon (RR 1.03; 95% CI 0.99 to 1.07) or with débridement (RR 1.04; 95% CI 0.95 to 1.14) did not yield significantly better outcomes but may have accelerated healing. The corneal epithelial healing outcome was improved when antiviral therapy was added to débridement (RR 1.21; 95% CI 1.04 to 1.42).

AUTHORS' CONCLUSIONS

Trifluridine and acyclovir are more effective than idoxuridine or vidarabine, and similar in therapeutic effectiveness. Brivudine and ganciclovir are at least as effective as acyclovir. While not improving outcome, the combination of interferon and an antiviral agent may speed healing. The effectiveness of corneal epithelial débridement is improved by an antiviral agent.

Topical ganciclovir in the treatment of acute herpetic keratitis

Herpetic keratitis is caused by herpes simplex virus (HSV) and is a common cause of corneal blindness. Following a primary ocular herpetic infection, latency of the virus occurs, followed by subsequent recurrences of herpetic keratitis. Such recurrences may lead to structural damage of the cornea. Recurrent herpetic keratitis is a common indication for corneal transplantation. Recurrences of herpetic keratitis in the corneal graft may lead to corneal graft rejection. Several antiviral agents for HSV are available, including the thymidine analogs. Prolonged use of thymidine analogs may lead to toxicity of the ocular surface, including epithelial keratitis, corneal ulcers, follicular conjunctivitis, and punctal occlusions. Availability of topical antiviral agents that are safe and effective in the treatment and prophylaxis of herpetic keratitis is highly desirable. Ganciclovir is a potent inhibitor of members of the herpes virus family. The drug has been used systemically for the treatment of cytomegalovirus (CMV) retinitis. Its hematologic toxicity secondary to systemic administration led to its limited use in herpetic infections. On the other hand, topical ganciclovir has been shown to be as safe and effective as acyclovir in the treatment of herpetic epithelial keratitis. Furthermore, topical ganciclovir can reach therapeutic levels in the cornea and aqueous humor following topical application. Several clinical trials have shown that topical ganciclovir 0.15% ophthalmic gel is safe and effective in the treatment and prophylaxis of herpetic epithelial disease. Long-term use of ganciclovir ophthalmic gel in patients with penetrating keratoplasty following herpetic keratitis has prevented recurrences of the disease. Topical ganciclovir ophthalmic gel is well tolerated, does not cause toxic effects on the ocular surface, and does not cause hematologic abnormalities. Clinical studies have underscored the potential role of ganciclovir ophthalmic gel in the treatment and prophylaxis of herpetic epithelial keratitis. Future randomized, controlled, multicenter, prospective clinical trials are needed to assess the long-term safety and efficacy of topical ganciclovir in the treatment and prevention of herpetic keratitis and uveitis.

Transcorneal permeation of L- and D-aspartate ester prodrugs of acyclovir: delineation of passive diffusion versus transporter involvement

PURPOSE

The aim of this study was to evaluate the contribution of amino acid transporters in the transcorneal permeation of the aspartate (Asp) ester acyclovir (ACV) prodrug.

METHODS

Physicochemical characterization, solubility and stability of acyclovir L-aspartate (L-Asp-ACV) and acyclovir D-aspartate (D-Asp-ACV) were studied. Transcorneal permeability was evaluated across excised rabbit cornea.

RESULTS

Solubility of L-Asp-ACV and D-Asp-ACV were about twofold higher than that of ACV. The prodrugs demonstrated greater stability under acidic conditions. Calculated pK(a) and logP values for both prodrugs were identical. Transcorneal permeability of L-Asp-ACV (12.1 +/- 1.48 x 10(-6) cm/s) was fourfold higher than D-Asp-ACV (3.12 +/- 0.36 x 10(-6) cm/s) and ACV (3.25 +/- 0.56 x 10(-6) cm/s). ACV generation during the transport process was minimal. L-Asp-ACV transport was sodium and energy dependent but was not inhibited by glutamic acid. Addition of BCH, a specific B(0,+) and L amino acid transporter inhibitor, decreased transcorneal L-Asp-ACV permeability to 2.66 +/- 0.21 x 10(-6) cm/s. L-Asp-ACV and D-Asp-ACV did not demonstrate significant difference in stability in ocular tissue homogenates.

CONCLUSION

The results demonstrate that enhanced transport of L-Asp-ACV is as a result of corneal transporter involvement (probably amino acid transporter B(0,+)) and not as a result of changes in physicochemical properties due to prodrug derivatization (permeability of D-Asp-ACV and ACV were not significantly different).