Efficacy of polyclonal antibodies for treatment of ocular herpes simplex infection.

PURPOSE: Herpes simplex virus (HSV) can cause corneal infections in humans and lead to permanent scarring, loss of vision, and blindness. Current treatment of epithelial HSV keratitis consists of using antiviral DNA analogs. In this study, we used in vitro and in vivo models to evaluate the efficacy of six polyclonal antibodies to HSV recombinant surface glycoprotein D in treating ocular epithelial HSV. METHODS: Confluent cultures of African Green monkey kidney fibroblasts (Vero cells) and normal 3-to 5-lb female New Zealand White rabbits were infected with HSV type 1, strain RE. In vitro virucidal and antiviral assays were performed, and the best of the compounds was chosen for the in vivo stage. Animals were carefully monitored until day 5 after HSV-1 inoculation, then arbitrarily divided into groups receiving, for 14 days, varying doses of: polyclonal antibodies four times a day, polyclonal antibodies three times a day, trifluorothymidine (current treatment of choice and the positive control) nine times a day, or 0.9% physiologic saline nine times a day. The animals were followed up in a masked fashion and carefully monitored for severity and resolution of the HSV infection by biomicroscopy (slit lamp) examination and viral cultures using standardized plaque assays. RESULTS: All six of the compounds tested were effective in vitro, but one compound in particular, SP-510-50, was superior. It was used for the in vivo testing and showed antiviral efficacy in a dose-dependent manner, and at dosing four times a day, it was of comparable efficacy to trifluorothymidine (nine times a day). CONCLUSIONS: We conclude that polyclonal antibodies to glycoprotein D appear to be effective antiviral agents in vitro and in vivo in a rabbit model of HSV-1 keratitis and show promise as a new antiviral treatment for ophthalmic use.

Recurrent ocular herpes simplex keratitis following excimer laser photorefractive keratectomy in a rabbit model.

PURPOSE: Reactivation of latent herpes simplex virus (HSV) by excimer laser photorefractive keratectomy(PRK) has been reported previously in the literature. This study evaluates the extent of such HSV reactivation and determines whether corneal de-epithelialization prior to PRK or the laser treatment itself induces this response. METHODS: Twenty three normal 1.5-2.5 kg New Zealand white rabbits were infected on the surface of the cornea with HSV-1, strain RE. The animals were monitored until resolution and then divided into two treatment groups: 1) de-epithelialization alone, and 2) de-epithelialization plus laser. Animals were evaluated in a masked fashion by clinical examination and viral cultures twice a week through day 28. RESULTS: The reactivation rate for group 1 (de-epithelization alone) was 0.0%, and for group 2 (PRK) was 67% by slit lamp biomicroscopy. Viral culture positivity rate matched these findings. CONCLUSIONS: Excimer laser (193 nm) treatment can trigger viral shedding and reactivation of herpetic ocular disease in the latently infected rabbit. De-epithelialization alone is not sufficient to cause such viral reactivation or keratitis. Our findings suggest that patients with a history of herpetic keratitis undergoing PRK are at increased risk of HSV reactivation as a result of exposure to the excimer laser.

Efficacy of cobalt chelates in the rabbit eye model for epithelial herpetic keratitis.

PURPOSE: A new class of antiviral agent, cobalt chelates (the CTC series), was evaluated for treating epithelial herpetic keratitis, consequent stromal disease being the major infectious cause of blindness in industrial nations. METHODS: Effects of CTC complexes were monitored in cell cultures and in a rabbit eye model, either infected with herpes simplex virus type 1 (HSV-1) or uninfected. Several antiviral concentrations of CTC complexes nontoxic to Vero cells were administered to rabbit eyes with HSV-1-induced keratitis. Corneal surface virus titers were measured, and corneal lesions of epithelial keratitis were monitored by slit-lamp microscopy and scored. Recovery rates and incidence were compared in eyes treated with CTC complexes, placebo, or clinically formulated trifluorothymidine (Viroptic), using nonparametric statistics. RESULTS: All CTC complexes inhibited HSV-1 replication in vitro, CTC-96 being best. CTC-96, CTC-23, and CTC-67 eliminated (<1 plaque-forming unit[pfu]) corneal surface HSV-1 (otherwise >10(5) pfu) in order of descending potency, but CTC-82 was ineffective. CTC-96 (either 5 microg/ml six times daily or 10 microg/ml five times daily) accelerated herpetic dendritic keratitis recovery better than or the same as trifluorothymidine (10 mg/ml nine times daily). CTC complexes were nontoxic to Vero cells continuously exposed to < or =25 microg/ml; 50 microg/ml of CTC 96 nine times daily did not irritate uninfected rabbit eyes. CONCLUSION: Topical CTC-96 applications were at least as effective as Viroptic in diminishing disease signs and corneal surface virus at concentrations less than one-thousandth that of Viroptic.

Effect of triggering epidermal Fc gamma receptors on the interleukin-2- and interleukin-6-induced upregulation of Ia antigen expression by murine epidermal Langerhans cells: the role of prostaglandins and cAMP.

Following incubation of murine epidermis in medium containing either interleukin-2 or interleukin-6, there is significant upregulation in the density of Ia+ epidermal Langerhans cells (to 159% and 175% of control, respectively). This cytokine-induced upregulation is abrogated by either rabbit or human IgG due to triggering of Fc gamma receptors. In contrast, human IgA does not inhibit the effect of interleukin-2 or interleukin-6. Using different isotypes of murine IgG, we have demonstrated that all subclasses are capable of inhibiting the cytokine-induced enhancement of Ia antigen, although IgG1 and IgG2b must be heat aggregated to be effective. The IgG-mediated events are dependent on prostaglandin synthesis because they can be blocked by the cyclooxygenase inhibitor indomethacin, 10 micrograms/ml. The responsible PG appears to be PGD2; in contrast to its known inhibitory effect on macrophages, PGE2 does not inhibit the upregulation of Ia antigen on Langerhans cells. In addition, these IgG-mediated events are dependent upon the generation of cAMP because they can be blocked by the adenylate cyclase inhibitor 2',5'-dideoxyadenosine, 1 mM. Despite the apparently central role of PGD2 and cAMP in this process, triggering of the Fc gamma R by different isotypes of IgG blocks upregulation of Ia via at least two different pathways. The inhibition caused by aggregated IgG1 or IgG2b, which bind to Fc gamma RII on Langerhans cells, is abrogated by para-bromophenacylbromide, an inhibitor of phospholipase A2. In contrast, the inhibition caused by monomeric IgG2a, which binds to Fc gamma RI most likely on keratinocytes, or monomeric IgG3, which probably binds to this same Fc gamma RI, is abrogated by staurosporine, an inhibitor of protein kinase C, as well as by W7, a calmodulin antagonist. Finally, 1,2 dioctanoyl-rac-glycerol, an activator of protein kinase C, mimics the Ig-mediated events. Based on these findings, as well as studies using monoclonal antibodies to the murine Fc gamma receptors I and II, we conclude that, as is the case in murine macrophages, triggering of an epidermal Fc gamma RI, most likely on keratinocytes, results in the generation of cAMP via a Ca(++)-dependent protein kinase C pathway, whereas triggering of an epidermal Fc gamma RII, most likely on Langerhans cells, results in the elevation of cAMP via a phospholipase A2-mediated pathway. In contrast to the situation for macrophages, PGD2 is a vital intermediate in both pathways, perhaps because Langerhans cells have receptors for only this prostaglandin.(ABSTRACT TRUNCATED AT 400 WORDS)

Immunosuppressive effects of transforming growth factor beta: inhibition of the induction of Ia antigen on Langerhans cells by cytokines and of the contact hypersensitivity response.

Recent reports show that transforming growth factor (TGF)-beta exerts a variety of immunosuppressive activities. The present study focuses on the effects of TGF-beta 1 on expression of Ia antigen by Langerhans cells. Although TGF-beta 1, in concentrations from 0.001 to 100 micrograms/ml, has no effect on constitutive expression of Ia antigen on these cells, the in vitro up-regulation of Ia antigen on the surface of LC by interleukin (IL)-1, tumor necrosis factor-alpha, interferon-gamma, IL-3, and granulocyte/macrophage-colony stimulating factor is inhibited by the concomitant addition of 1 microgram/ml TGF-beta 1. In contrast, TGF-beta 1 has no effect on the up-regulation induced by IL-2 or IL-6. In this report, the activity of TGF-beta closely resembles that of Cyclosporine A (CsA). Similar results are seen in vivo when either TGF-beta 1 (5 micrograms, intraperitoneally [ip], daily on days 0-3) or CsA (1 mg, subcutaneously [sc], twice daily on days 0-3) are given together with IL-2 (500 U, intraperitoneally [ip], twice daily on days 1-3) or interferon-gamma (4,000 U, ip, twice daily on days 1-3). Given the important role of Ia expression in cell-mediated immune reactions, the effect of TGF-beta on contact sensitivity was next investigated. In doses of 5 micrograms, ip, daily on days 6-8, TGF-beta inhibits the expression of contact reactivity in animals sensitized on day 0 and challenged on day 7. In contrast, no effect is observed on the induction of contact sensitivity in mice given TGF-beta 1 on days--1 to 2, sensitized on day 0, and challenged on day 7. The possible importance of antagonism between TGF-beta and other cytokines, especially IFN-gamma, involved in the elicitation of contact hypersensitivity reactions is discussed.

Enhancement by various cytokines or 2-beta-mercaptoethanol of Ia antigen expression on Langerhans cells in skin from normal aged and young mice. Effect of cyclosporine A.

The number of Ia+ Langerhans cells (LC) in skin from aged (16- to 18-mo old) BALB/c mice is approximately 40% lower than in skin from young (2- to 3-mo old) mice. Overnight incubation at 37 degrees C with a variety of cytokines, including IL-1, IL-2, IL-3, IL-4, IL-6, TNF-alpha, IFN-gamma, and granulocyte/macrophage-CSF, causes a significant increase in the Ia expression on LC and raises the number of Ia+ cells by at least 300/mm2 in skin from both young and old mice. At 1 to 5 x 10(-5) M, 2-ME has a similar effect. The percentage increment in Ia+ cells is much higher for skin from aged mice than from young mice, particularly with IL-3, which appears to reconstitute the number of Ia+ LC in skin from aged mice to that of IL-3 exposed skin from young mice. Under the incubation conditions of our experiments, neither keratinocytes nor Thy-1+ dendritic cells acquire Ia Ag. Addition of 10 micrograms/ml cyclosporine A to the medium abolishes the effect of 2-ME and of all of the cytokines except IL-2 and IL-6. These results demonstrate the presence of a significant population of Ia- LC in the epidermis of both young and aged mice. It is suggested that epidermal production of cytokines may be of importance in the maintenance of constitutive Ia expression on LC. The possible interaction between keratinocytes and LC and the effect of aging on this process are discussed.