Herpes simplex virus in the eye

The novel role of lymphatic vessels in the pathogenesis of ocular diseases

Historically, the eye has been considered as an organ free of lymphatic vessels. In recent years, however, it became evident, that lymphatic vessels or lymphatic-like vessels contribute to several ocular pathologies at various peri- and intraocular locations. The aim of this review is to outline the pathogenetic role of ocular lymphatics, the respective molecular mechanisms and to discuss current and future therapeutic options based thereon. We will give an overview on the vascular anatomy of the healthy ocular surface and the molecular mechanisms contributing to corneal (lymph)angiogenic privilege. In addition, we present (i) current insights into the cellular and molecular mechanisms occurring during pathological neovascularization of the cornea triggered e.g. by inflammation or trauma, (ii) the role of lymphatic vessels in different ocular surface pathologies such as dry eye disease, corneal graft rejection, ocular graft versus host disease, allergy, and pterygium, (iii) the involvement of lymphatic vessels in ocular tumors and metastasis, and (iv) the novel role of the lymphatic-like structure of Schlemm's canal in glaucoma. Identification of the underlying molecular mechanisms and of novel modulators of lymphangiogenesis will contribute to the development of new therapeutic targets for the treatment of ocular diseases associated with pathological lymphangiogenesis in the future. The preclinical data presented here outline novel therapeutic concepts for promoting transplant survival, inhibiting metastasis of ocular tumors, reducing inflammation of the ocular surface, and treating glaucoma. Initial data from clinical trials suggest first success of novel treatment strategies to promote transplant survival based on pretransplant corneal lymphangioregression.

The Identification and Treatment of Common Skin Infections

Skin conditions are a common problem addressed by medical providers. Up to 25% of individuals in the United States will seek attention for these conditions each year. The same problem occurs in the athletic training room, where athletes with infectious skin conditions can be seen. Most conditions are simple and can be treated without concern for spread to susceptible athletes. However, others can be quite serious and spread rapidly through a team and opponents during competition. Knowledge of the different types of skin infections is necessary to help treat these athletes and prevent spread to others. With proper diagnosis and treatment, certified athletic trainers can keep the athlete off the field of play for a minimum period and prevent transmission.

Cytokine profile and cytoskeletal changes after herpes simplex virus type 1 infection in human trabecular meshwork cells

Uveitis caused by herpes simplex virus (HSV)‐1 is characterized by increased intraocular pressure (IOP) in the presence of anterior chamber inflammation. Despite their clinical significance, the pathogenic changes associated with HSV‐1 infection in trabecular meshwork (TM) cells, the key cell type regulating IOP, have not been completely elucidated. In this study, cytokine array analyses showed a significant stepwise increase in monocyte chemoattractant protein (MCP)‐1 expression upon HSV‐1 infection in TM cells (p < 0.05). HSV‐1 infection led to downregulation of fibrogenic molecules (fibronectin, α‐smooth muscle actin, connective tissue growth factor and TGF‐β1). Notably, HSV‐1 infection caused a significant increase in actin stress fibres, with a twofold increase in active RhoA, which was enhanced by treatment with TGF‐β1 and inhibited by treatment with the Rho‐kinase inhibitor, Y‐27632. TM cells treated with MCP‐1 exhibited a dose‐dependent increase in actin stress fibres compared to untreated TM cells. Our study suggests that HSV‐1 infection in TM cells increases cell contractile activity rather than fibrotic changes in the extracellular matrix (ECM) components. Taken together, these observations demonstrate the enhanced expression of MCP‐1 and TM cell contractile activity upon HSV‐1 infection and events with potential implications for the pathobiology of abrupt IOP elevation in HSV‐1 anterior uveitis.

Herpes simplex virus infections in solid organ transplantation: Guidelines from the American Society of Transplantation Infectious Diseases Community of Practice

These updated guidelines from the Infectious Diseases Community of Practice of the American Society of Transplantation review the diagnosis, prevention, and management of HSV in the pre- and post-transplant period. A majority of transplant recipients are seropositive for HSV-1 or 2. Compared with immunocompetent persons, SOT recipients shed HSV more frequently, have more severe clinical manifestations, and are slower to respond to therapy. Most HSV infection is diagnosed on clinical grounds, but patients may present with atypical lesions and/or other clinical manifestations. Acquisition from the donor is rare. Polymerase chain reaction is the preferred diagnostic test unless culture is needed for resistance testing. For limited mucocutaneous lesions, oral therapy can be used; however, in severe, disseminated, visceral or CNS involvement, acyclovir doses of up to 10 mg/kg every 8 hours intravenously should be initiated. Acyclovir-resistant HSV is less common in SOT patients than in HSCT and can be treated with foscarnet, though other novel therapies are currently under investigation. HSV-specific prophylaxis should be considered for all HSV-1 and HSV-2-seropositive organ recipients who are not receiving antiviral medication for CMV prevention that has activity against HSV.

The relationship of graft survival and herpes simplex virus latency in recipient corneal buttons

PURPOSE

To demonstrate relationship between herpes simplex virus (HSV) corneal latency and graft survival.

METHODS

Prospective case control study. 28 recipient corneal buttons and donor cornea-scleral remnants were examined for HSV DNA with polymerase chain reaction (PCR). None of the recipient had a history of HSV infection. Serum samples of graft recipients were analyzed for the presence of anti-HSV IgG and IgM with enzyme-linked immunosorbent assay technique. All corneas were free of stromal scarring or epithelial defect before sampling and had an endothelial cell density of >2000 cells/mm(2).

RESULTS

In twenty three patients (82%) anti-HSV IgG was detected in serum. In none of the recipients anti-HSV IgM was positive. HSV DNA was positive in six out of twenty eight (21%) of the recipient corneal buttons and none of the donor cornea-scleral remnants. In eighteen-months follow-up period three out of six (50%) HSV DNA positive and one out of twenty-two (4.5%) HSV DNA negative patients experienced late endothelial failure that was statistically significantly different (p = 0.022).

CONCLUSION

Even without a history of HSV keratitis, presence of latent HSV virus in recipient cornea is an important risk factor for subsequent graft survival.

Topical treatment with nerve growth factor in an animal model of herpetic keratitis

BACKGROUND

In vitro and in vivo studies demonstrated the antiviral efficacy of nerve growth factor (NGF) and its cyto-protective effect in herpes simplex virus (HSV)-infected cells. The aims of this study were to evaluate the role of endogenous NGF in HSV corneal infection, and the effects of topical NGF treatment on herpetic keratitis.

METHODS

Herpetic keratitis was induced in 40 rabbits with the HSV-1 McKrae strain. Animals were divided into four groups, and treated with topical neutralizing anti-NGF antibodies, NGF, acyclovir or balanced salt solution (BSS) respectively. The clinical course of HSV keratitis was evaluated and scored by slit-lamp examination. In addition, biochemical (immunohistochemistry for glycoprotein D) and molecular (nested PCR for glycoprotein D) analyses were carried out to estimate viral replication.

RESULTS

Treatment with anti-NGF antibodies induced a more severe keratitis associated with increased biochemical and molecular markers of active viral replication. Two animals in this group developed lethal HSV encephalitis. Conversely, topical treatment with NGF induced a significant amelioration of clinical and laboratory parameters when compared to the BSS treated group (control). No significant differences were observed between NGF- and acyclovir-treated groups.

CONCLUSIONS

This study demonstrated the crucial role of endogenous NGF in herpetic keratitis. The comparable effects of NGF and acyclovir confirm the antiviral activity of NGF, and indicate a potential use of topical NGF in herpetic keratitis.

Epithelial herpetic simplex keratitis recurrence and graft survival after corneal transplantation in patients with and without atopy

PURPOSE

To compare the incidence of herpes simplex virus (HSV) epithelial recurrence and graft survival after penetrating keratoplasty (PK) in patients with and without self-reported atopy.

DESIGN

Retrospective cohort comparative study.

METHODS

SETTING

Cornea Service, Wills Eye Hospital.

STUDY POPULATION

Patients who presented with previously diagnosed ocular HSV between March 2003 and March 2004 and who underwent primary PK for ocular HSV at the Cornea Service. From the 58 patients invited, 49 patients (50 eyes) were included. Nine patients were ineligible in accordance with the exclusion criteria: no active classic HSV episode before PK, immunosuppression, less than one year of follow-up, previous history of PK before presentation at the Service. Eligible patients filled out a questionnaire regarding their history of atopic disease, considering: presence of allergic rhinitis, asthma, or atopic dermatitis. Ocular history was obtained through chart review. main outcome measures: Incidence of epithelial HSV recurrences and corneal graft survival in both groups.

RESULTS

Each group (atopic and nonatopic) included 25 eyes. The atopic patients had a mean incidence of 0.07 episode/eye year (SD +/- 0.9) compared with 0.12/eye year (standard deviation [SD] +/- 0.21) in the nonatopics (P = .002). At 10 years of follow-up, the survival rate in the atopics was of 92% and in the nonatopics was of 79% (P = .88).

CONCLUSIONS

Nonatopics had significantly more epithelial recurrences after PK compared to atopics; however, both groups presented low incidences of recurrences and high graft survival rates.

New onset of herpes simplex virus epithelial keratitis after penetrating keratoplasty

PURPOSE

To report a series of patients with no previous history of herpes simplex virus (HSV) infection who had new onset of herpetic keratitis after penetrating keratoplasty (PK).

DESIGN

Noncontrolled, retrospective case series.

METHODS

We included in the study the patients who had new onset of herpetic keratitis after penetrating keratoplasty for corneal diseases unrelated to HSV infection who were seen at the Cornea Service at Wills Eye Hospital (Philadelphia, Pennsylvania) from January 1996 to December 2002. The diagnosis of HSV epithelial keratitis was based on clinical characteristics of either a classic herpetic dendrite, a geographic ulcer, or a nonhealing epithelial defect that responded only to antiviral therapy.

RESULTS

Fourteen patients were included in the study. Eight of these (57%) had presented with a geographic ulcer whereas six patients (43%) had a classic dendrite. The most common primary corneal disease that led to PK was pseudophakic bullous keratopathy (36%), followed by keratoconus (29%), Fuchs dystrophy (21%), and corneal scar unrelated to HSV (14%).

CONCLUSIONS

The ophthalmologist should be aware of the possibility of herpetic keratitis in eyes after PK, even in patients with no previous history of HSV infection.

Cutaneous manifestations of disease in athletes

In this first part of a two part series, we will discuss infectious means of skin injury and contact sensation in regard to athletic participation. Part 2 will address mechanical means and environmental means of skin injury as well as performance enhancing drugs used in sports and their effects on the skin.

Caspase-3-dependent reactivation of latent herpes simplex virus type 1 in sensory neuronal cultures

Life-long latent herpes simplex virus type 1 (HSV-1) is harbored in sensory neurons where sporadic reactivation occurs. Reactivation stimuli may involve activation of apoptotic signaling in the neuron. Previous experiments have demonstrated that reactivation of latent HSV-1 in dorsal root ganglion (DRG) neuronal cultures occurred following nerve growth factor (NGF) deprivation. NGF deprivation stimulates apoptotic signaling by activating the proapoptotic proteolytic enzyme, caspase-3. When DRG neuronal cultures harboring latent HSV-1 were treated with a caspase-3-specific inhibitor, NGF deprivation-induced reactivation was significantly reduced. Interestingly, the caspase-3 inhibitor had no effect on productive HSV-1 infection. Furthermore, activation of caspase-3 with either C2-ceramide or a recombinant adenovirus expressing caspase-3 caused significant HSV-1 reactivation.

Capsaicin-induced reactivation of latent herpes simplex virus type 1 in sensory neurons in culture

Herpes simplex virus type 1 (HSV-1) produces a life-long latent infection in neurons of the peripheral nervous system, primarily in the trigeminal and dorsal root ganglia. Neurons of these ganglia express high levels of the capsaicin receptor, also known as the vanilloid receptor-1 (VR-1). VR-1 is a non-selective ion channel, found on sensory neurons, that primarily fluxes Ca(2+) ions in response to various stimuli, including physiologically acidic conditions, heat greater than 45 degrees C and noxious compounds such as capsaicin. Using an in vitro neuronal model to study HSV-1 latency and reactivation, we found that agonists of the VR-1 channel - capsaicin and heat - resulted in reactivation of latent HSV-1. Capsaicin-induced reactivation of HSV-1 latently infected neurons was dose-dependent. Additionally, activation of VR-1 at its optimal temperature of 46 degrees C caused a significant increase in virus titres, which could be attenuated with the VR-1 antagonist, capsazepine. VR-1 activation that resulted in HSV-1 reactivation was calcium-dependent, since the calcium chelator BAPTA significantly reduced reactivation following treatment with caspsaicin and forskolin. Taken together, these results suggest that activation of the VR-1 channel, often associated with increases in intracellular calcium, results in HSV-1 reactivation in sensory neurons.

The outcome of corneal grafting in patients with stromal keratitis of herpetic and non-herpetic origin

AIM

To evaluate the outcome of corneal grafting in patients with stromal keratitis of herpetic (HSK) and non-herpetic origin, using predefined diagnostic criteria and standardised postoperative therapeutic strategies.

METHODS

384 adult immunocompetent recipients of a corneal graft for herpetic (n = 186) or non-herpetic (n = 198) keratitis were followed up prospectively for up to 5 years.

RESULTS

The herpetic group displayed significantly more corneal vascularisation (p = 0.013), more epithelial defects (p = 0.049), lower corneal sensitivity (p <0.001), more graft rejection episodes (p = 0.002), and required larger grafts (p<0.001). However, the postoperative course of visual acuity, endothelial cell numerical density, and rate of graft failures were similar in both groups. After 5 years, cumulative probability of graft survival in HSK patients (40.85%) was similar to that observed in individuals with non-herpetic keratitis (50.15%; log rank = 0.874; relative risk: 1.04).

CONCLUSION

Despite a markedly higher preoperative risk profile in herpetic eyes, the functional outcomes of grafts in individuals with keratitis of herpetic or non-herpetic origin were similar. Probably the most important contribution is a consequent close follow up and a therapeutic strategy including systemic prophylaxis of viral recurrence and of graft rejection by well adopted local steroid therapy.

Detection of herpes simplex virus type 1, 2 and varicella zoster virus DNA in recipient corneal buttons

AIM

To study the value of polymerase chain reaction (PCR) analysis, to detect viral DNA in recipient corneal buttons taken at the time of penetrating keratoplasty (PKP) in patients with an initial diagnosis of herpetic stromal keratitis (HSK). Since HSK has a tendency to recur, an accurate diagnosis of previous HSK could be the reason to start antiviral treatment immediately, thereby possibly decreasing the number of graft failures due to recurrent herpetic keratitis.

METHODS

Recipient corneal buttons and aqueous humour (AH) samples were obtained at the time of PKP from HSK patients (n=31) and from other patients (n=78). Eye bank corneas were also used (n=23). Herpes simplex virus type 1 (HSV-1), type 2 (HSV-2), and varicella zoster virus (VZV) infection were assessed by PCR and antibody detection.

RESULTS

The clinical diagnosis HSK could be confirmed by PCR for HSV-1 in 10/31 (32%). In these corneal buttons HSV-2 DNA was detected in 1/31 (3%) and VZV DNA in 6/31 (19%). Intraocular anti-HSV antibody production was detected in 9/28 AH samples tested (32%). In the other patient derived corneas HSV-1 DNA was detected in 13/78 (17%), including eight failed corneal grafts without clinically obvious herpetic keratitis in the medical history. In clear eye bank corneas HSV-1 was detected in 1/23 (4%).

CONCLUSIONS

PCR of HSV-1 on corneal buttons can be a useful diagnostic tool in addition to detection of intraocular anti-HSV antibody production. Furthermore, the results were suggestive for the involvement of corneal HSV infection during allograft failure of corneas without previous clinical characteristic signs of herpetic keratitis.

Propranolol suppression of ocular HSV-1 recurrence and associated corneal lesions following spontaneous reactivation in the rabbit

PURPOSE

Hyperthermia has been shown to induce HSV-1 ocular shedding in mice. Systemic administration of propranolol significantly reduced the recovery of infectious virus in the tears, cornea, and trigeminal ganglia of mice subjected to hyperthermia. The present study was performed to determine the effects of systemic propranolol on ocular shedding and recurrent corneal epithelial lesions in the rabbit model.

METHODS

New Zealand white rabbits were infected with HSV-1 strain McKrae or 17Syn+. After latency was established, the animals were treated with systemic propranolol or saline (control) and examined by slit lamp biomicroscopy for corneal lesion. Tear film swabs were cultured to determine the frequency and duration of viral shedding.

RESULTS

Propranolol caused a significant reduction in the frequency and duration of ocular HSV-1 shedding and a reduction in the frequency of recurrent corneal epithelia disease, compared with saline treatment.

CONCLUSIONS

These results suggest that beta-adrenergic receptor blockers such as propranolol could be useful in suppressing HSV-1 ocular recurrences and corneal disease.

Size dependent variation in the fractal dimensions of herpes simplex epithelial keratitis

Dendritic ulcers, the commonest manifestation of herpes simplex epithelial keratitis (HSEK) are fractals. It is likely that their fractal properties alter if they progress to a geographic appearance. This study investigates the relationship of maximum ulcer diameter (Feret's diameter) to area (Dm) and perimeter fractal dimensions (Ds), parameters of the complexity of their areas and outlines respectively. For dendritic ulcers in the size range of 1.6-3.2 mm, Dm = 1.41 +/- 0.06 and Ds = 1.40 +/- 0.04 (mean +/- SD). With increasing ulcer size, a progressive divergence of the values of Dm and Ds occurred, such that values of 1.75 and 1.22 respectively were found at a maximum diameter of 8.4 mm. These results imply that as ulcers enlarge, their outlines become less irregular and they fill more of a 2-dimensional plane. Dm and Ds are useful parameters in quantifying the progression of HSEK from dendritic to amoeboid morphology and could have a role in the assessment of ulcer response to pharmacological intervention. A knowledge of the fractal properties of HSEK may increase understanding of the mechanisms of ulcer formation and viral spread.