Interleukin-10 (IL-10) ameliorates corneal disease in a mouse model of recurrent herpetic keratitis

The immunobiology of corneal HSV-1 infection and herpetic stromal keratitis

SUMMARYHuman alphaherpesvirus 1 (HSV-1) is a highly successful neurotropic pathogen that primarily infects the epithelial cells lining the orofacial mucosa. After primary lytic replication in the oral, ocular, and nasal mucosal epithelial cells, HSV-1 establishes life-long latency in neurons within the trigeminal ganglion. Patients with compromised immune systems experience frequent reactivation of HSV-1 from latency, leading to virus entry in the sensory neurons, followed by anterograde transport and lytic replication at the innervated mucosal epithelial surface. Although recurrent infection of the corneal mucosal surface is rare, it can result in a chronic immuno-inflammatory condition called herpetic stromal keratitis (HSK). HSK leads to gradual vision loss and can cause permanent blindness in severe untreated cases. Currently, there is no cure or successful vaccine to prevent latent or recurrent HSV-1 infections, posing a significant clinical challenge to managing HSK and preventing vision loss. The conventional clinical management of HSK primarily relies on anti-virals to suppress HSV-1 replication, anti-inflammatory drugs (such as corticosteroids) to provide symptomatic relief from pain and inflammation, and surgical interventions in more severe cases to replace damaged cornea. However, each clinical treatment strategy has limitations, such as local and systemic drug toxicities and the emergence of anti-viral-resistant HSV-1 strains. In this review, we summarize the factors and immune cells involved in HSK pathogenesis and highlight alternate therapeutic strategies for successful clinical management of HSK. We also discuss the therapeutic potential of immunoregulatory cytokines and immunometabolism modulators as promising HSK therapies against emerging anti-viral-resistant HSV-1 strains.

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.

Resolvin D1 Inhibits Corneal Inflammation in Staphylococcus Aureus Keratitis

PURPOSE

To investigate the role of lipid mediator, resolvin D1 (RvD1), in corneal inflammation.

METHODS

The anti-inflammatory effect of RvD1 on stimulated human corneal epithelial cells (HCECs) was assessed. C57BL/6 mice corneas were abraded and treated with RvD1 after stimulation with Staphylococcus aureus. Cytokine levels in the corneas, cervical drainage lymph nodes (DLNs), and spleens were measured. Anterior segment photography and optical coherence tomography quantified the changes in corneal thickness and haziness. Neutrophil infiltration in the cornea was examined by haematoxylin and eosin (H&E) staining and immunohistochemistry.

RESULTS

RvD1 significantly inhibited cytokine production in HCECs and mouse corneas, cervical DLNs, and spleens while stimulating interleukin-10 (IL-10) production. Corneal opacity development, thickening, and neutrophil infiltration significantly reduced in response to RvD1 stimulation in the S. aureus-infected mice corneas.

CONCLUSION

RvD1 inhibited S. aureus-induced corneal inflammation. These results potentiate RvD1 as an anti-inflammatory therapy for patients with corneal inflammation induced by bacterial keratitis.

Activation of the STAT5 Signaling Pathway by Yiqi Jiedu Formula Induces Regulatory T Cell-Mediated Alleviation of Corneal Immunopathological Damage in Mice With Recurrent Herpes Simplex Keratitis

This study aimed to investigate the effect of Yiqi Jiedu (YQJD) formula on the repair of corneal lesions in mice with recurrent herpes simplex virus keratitis (HSK). Sixty female BALB/c mice were randomly divided into three groups: a normal control group (Naive), a recurrence model group (Re), and a YQJD group. After inducing recurrence by ultraviolet irradiation, the ocular surfaces of different groups of mice were observed using a slit lamp and photographed, and ocular surface scores were calculated. The abundance of CD4⁺CD25⁺Foxp3⁺ regulatory T (Treg) cells was determined by flow cytometry in peripheral blood and spleen cells. The CD4⁺Foxp3⁺ Tregs were assessed by immunofluorescence in the cornea. The levels of the cytokines IL-10 and TGF-β in serum and splenocyte culture supernatants were detected by enzyme-linked immunosorbent assay. Furthermore, the activation status of the STAT5 signaling pathway was examined by protein blotting, and the effect of YQJD on Treg cells through inhibition of the STAT5 pathway was observed in vitro. YQJD alleviated corneal inflammation by enhancing the STAT5 signaling pathway, thereby promoting the differentiation of CD4⁺CD25⁺Foxp3⁺ Treg cells, increasing the levels of anti-inflammatory cytokines such as IL-10 and TGF-β, and maintaining immune tolerance. YQJD increased the proportion of CD4⁺Foxp3⁺ Treg cells; also, in the cornea, YQJD inhibited the aggregation of macrophages and CD4⁺ cells and reduced the proportion of Th17 cells and other pro-inflammatory cells. Moreover, YQJD promoted the secretion of IL-4 to protect the cornea, leading to the mitigation of corneal immunopathological damage. YQJD reduced corneal lesions in recurrent HSK mice by stimulating Treg cells, inducing immune tolerance, and inhibiting corneal immunopathological responses via modulation of the STAT5 signaling pathway.

Biomolecular evaluation of cryopreserved amniotic membranes for ophthalmological use by ELISA and RT-PCR at one and eighteen months

PURPOSE

To study the presence of certain proteins - EGF (epidermal growth factor), KGF (keratinocyte growth factor), IL-10 (interleukin 10), HGF (hepatocyte growth factor), Alpha2-macroglobulin and IL-1RA (interleukin 1 receptor antagonist) in cryopreserved amniotic membranes at 1 and 18 months and, as a secondary objective, to detect mRNA corresponding to KGF, IL-1Ra, Alpha2-macroglobulin, Fas Ligand, TGF beta (transforming growth factor beta) and Lumican by RT-PCR in membranes preserved at 1 and 18 months.

MATERIAL AND METHODS

Four samples of amniotic membrane were divided into 2 groups: the first group (N=2) cryopreserved for 1 month and the second group (N=2) cryopreserved for 18 months, in order to be studied by RT-PCR and ELISA.

RESULTS

RT-PCR detected KGF, IL-1Ra, Alpha2-macroglobulin, Fas Ligand, and Lumican. Of these, FAS Ligand mRNA was found in samples preserved for 1and 18 months. KGF, Lumican, and alpha2-microglobulin mRNA were found only at 1 month, and IL-1Ra mRNA was absent in both sample groups. RT-PCR for TGF-beta was inconclusive. ELISA was performed for detection and quantification of 6 proteins (EGF, KGF, IL-10, HGF, Alpha2-macroglobulin and IL-1Ra) in both amniotic membrane groups. All 6 proteins were found in all samples, with a lower concentration at 18 months compared to 1 month of preservation.

CONCLUSION

This study shows that membranes cryopreserved in 50% glycerol for 18 months do retain the proteins necessary for regeneration of the corneal surface, giving these membranes their biochemical properties.

Topical Administration of SLN-Based Gene Therapy for the Treatment of Corneal Inflammation by De Novo IL-10 Production

One of the main challenges in gene therapy is the issue of delivery, and it is especially relevant for the success of gene therapy in the cornea. In the present work, eye drops containing biocompatible non-viral vectors based on solid lipid nanoparticles (SLNs) as gene delivery systems to induce the expression of interleukin 10 (IL-10) were designed to address the treatment of corneal inflammation. Two kinds of SLNs combined with different ligands (protamine, dextran, or hyaluronic acid (HA)) and formulated with polyvinyl alcohol (PVA) were prepared. SLN-based vectors were characterized in terms of size, adhesiveness, viscosity, and pH, before topical administration to wild type and IL-10 knock out (KO) mice. The formulations showed a homogenous particle size below 400 nm and a positive surface charge to favor bioadhesion; the incorporation of PVA improved the corneal penetration. After three days of treatment by topical instillation, SLN-based vectors mainly transfected corneal epithelial cells, HA-formulations being the most effective ones. IL-10 was capable of reaching even the endothelial layer. Corneal sections showed no histological change and formulations seemed to be well tolerated after repeated topical administration. These promising results highlight the possible contribution of non-viral gene augmentation therapy to the future clinical approach of corneal gene therapy.

Pathogenesis of Herpes Stromal Keratitis: Immune Inflammatory Response Mediated by Inflammatory Regulators

Herpes stromal keratitis (HSK) is one of the primary diseases that cause vision loss or even blindness after herpes simplex virus (HSV)-1 infection. HSK-associated vision impairment is predominantly due to corneal scarring and neovascularization caused by inflammation. In the infected cornea, HSV can activate innate and adaptive immune responses of host cells, which triggers a cascade of reactions that leads to the release of inflammatory cytokines, chemokines, microRNA, and other regulatory factors that have stimulating or inhibitory effects on tissue. Physiologically, host cells show homeostasis. In this review, we summarize the factors involved in HSK pathogenesis from the perspective of immunity, molecules, and pathological angiogenesis. We also describe in detail the pathogenesis of chronic inflammatory lesions of the corneal stroma in response to HSV-1 infection.

Pigment Epithelium-derived Factor secreted by corneal epithelial cells regulates dendritic cell maturation in dry eye disease

PURPOSE

In this study, we quantify Pigment Epithelium-derived Factor (PEDF) secreted by corneal epithelial cells and evaluate its immunomodulatory functions in a murine model of dry eye disease (DED).

METHODS

We induced DED in female C57BL/6 mice using a controlled environment chamber for 14 days. We quantified mRNA expression of Serpinf1 gene and PEDF protein synthesis by corneal epithelial cells (CEpCs) using RT-PCR and ELISA. CEpCs from normal or DED mice were cultured with IFNγ-stimulated-dendritic cells (DCs) for 24 h, and expression of MHC-II and CD86 by DCs was determined using flow cytometry. Next, we either added recombinant PEDF (rPEDF) or anti-PEDF antibody to co-culture, and DC expression of the above maturation markers was quantified. Lastly, we treated DED mice with either topical rPEDF, anti-PEDF Ab or murine serum albumin (MSA), and DC maturation, expression of pro-inflammatory cytokines, and DED severity were investigated.

RESULTS

Serpinf1 mRNA expression and PEDF protein production levels by CEpCs were upregulated in DED. CEpCs from DED mice exhibited an enhanced suppressive effect on the expression of MHC-II and CD86 by DCs, compared to normal mice. This effect was abolished by blocking endogenous PEDF with anti-PEDF Ab or enhanced by supplementing with rPEDF. Treatment with anti-PEDF antibody blocked the effect of endogenous-PEDF and increased DC maturation, expression of pro-inflammatory cytokines in conjunctivae, and exacerbated disease severity in DED mice. Conversely, topical rPEDF enhanced the suppressive effect of endogenous PEDF on DC maturation, decreased expression of pro-inflammatory cytokines in conjunctivae, and reduced disease severity.

CONCLUSIONS

The results from our study elucidate the role of PEDF in impeding DC maturation, and suppression of ocular surface inflammation, explicating a promising therapeutic potential of PEDF in limiting the corneal epitheliopathy as a consequence of DED.

Urban air pollution induces redox imbalance and epithelium hyperplasia in mice cornea

The aim of the study was to evaluate the time course of the effects of urban air pollutants on the ocular surface, focusing on the morphological changes, the redox balance, and the inflammatory response of the cornea. 8-week-old mice were exposed to urban or filtered air (UA-group and FA-group, respectively) in exposure chambers for 1, 2, 4, and 12 weeks. After each time, the eyes were enucleated and the corneas were isolated for biochemical analysis. UA-group corneas exhibited a continuous increase in NADPH oxidase-4 levels throughout the exposure time, suggesting an increased production of reactive oxygen species (ROS). After 1 week, an early adaptive response to ROS was observed as an increase in antioxidant enzymes. After 4 weeks, the enzymatic antioxidants were decreased, meanwhile an increase of the glutathione was shown, as a later compensatory antioxidant response. However, redox imbalance took place, evidenced by the increased oxidized proteins, which persisted up to 12 weeks. At this time point, corneal epithelium hyperplasia was also observed. The inflammatory response was modulated by the increase in IL-10 levels after 1 week, which early regulates the release of TNF-α and IL-6. These results suggest that air pollution alters the ocular surface, supported by the observed cellular hyperplasia. The redox imbalance and the inflammatory response modulated by IL-10 play a key role in the response triggered by air pollutants on the cornea. Taking into account this time course study, the ocular surface should also be considered as a relevant target of urban air pollutants.

Targeting corneal inflammation by gene therapy: Emerging strategies for keratitis

Inflammation is the underlying process of several diseases within the eye, specifically in the cornea. Current treatment options for corneal inflammation or keratitis, and related neovascularization, are restricted by limited efficacy, adverse effects, and short duration of action. Gene therapy has shown great potential for the treatment of diseases affecting the ocular surface, and major efforts are being targeted to inflammatory mediators and neovascularization, in order to develop potential treatments for corneal inflammation. Gene therapy to treat ocular disorders is still starting, and current therapies are primarily experimental, with most human clinical trials still in research state, although some of them have already shown encouraging results. In this review, we focus on the progress and challenges of gene therapy to treat corneal inflammation. After introducing the inflammation process, we present the main nucleic acid delivery systems, including viral and non-viral vectors, and the most studied strategies to address the therapy: control of neovascularization and regulation of pro- and anti-inflammatory cytokines.

CXCL9 compensates for the absence of CXCL10 during recurrent Herpetic stromal keratitis

Herpetic stromal keratitis (HSK) is a disease that is typically associated with reactivation of a latent HSV-1 infection. This disease is driven, in part, by chemokines that recruit leukocytes to the cornea. Surprisingly, neutralization of CXCL10 significantly reduced disease, while B6-CXCL10-/- mice exhibited worse disease compared with similarly infected wild-type controls. We hypothesized that compensatory up-regulation of CXCL9 occurs in the absence of CXCL10. Analysis of CXCL9 expression in HSV-1-infected B6 mice and B6-CXCL10-/- mice revealed significantly more CXCL9 in B6-XCL10-/- mice. Treatment of B6 and B6-CXCL10-/- mice with neutralizing antibodies to CXCL9 reduced HSK scores in B6-CXCL10-/-, but not B6 mice. We conclude that CXCL10 production worsens HSK and that CXCL9 may compensate in CXCL10-deficient animals. These studies identify the critical role that CXCL10 plays in the pathogenesis of recurrent HSK, and that CXCL9 displays its importance when CXCL10 is absent.

Immunological aspects of acute and recurrent herpes simplex keratitis

Herpes simplex keratitis (HSK) belongs to the major causes of visual morbidity worldwide and available methods of treatment remain unsatisfactory. Primary infection occurs usually early in life and is often asymptomatic. Chronic visual impairment and visual loss are caused by corneal scaring, thinning, and vascularization connected with recurrent HSV infections. The pathogenesis of herpetic keratitis is complex and is still not fully understood. According to the current knowledge, corneal scarring and vascularization are the result of chronic inflammatory reaction against HSV antigens. In this review we discuss the role of innate and adaptive immunities in acute and recurrent HSV ocular infection and present the potential future targets for novel therapeutical options based on immune interventions.

Corneal lymphangiogenesis in herpetic stromal keratitis

Corneal lymphangiogenesis is the extension of lymphatic vessels into the normally alymphatic cornea, a process that compromises the cornea's immune-privileged state and facilitates herpetic stromal keratitis (HSK). HSK results most commonly from infection by herpes simplex virus-1 (HSV-1) and is characterized by immune- and inflammation-mediated damage to the deep layers of the cornea. Current research demonstrates the potential of anti-lymphangiogenic therapy to decrease and prevent herpes-induced lymphangiogenesis.

Broadening the repertoire of functional herpes simplex virus type 1-specific CD8+ T cells reduces viral reactivation from latency in sensory ganglia

A large proportion of the world population harbors HSV type 1 (HSV-1) in a latent state in their trigeminal ganglia (TG). TG-resident CD8(+) T cells appear important for preventing HSV-1 reactivation from latency and recurrent herpetic disease. In C57BL/6J mice, half of these cells are specific for an immunodominant epitope on HSV-1 glycoprotein B, whereas the other half are specific for 18 subdominant epitopes. In this study, we show that the CD8(+) T cell dominance hierarchy in the TG established during acute infection is maintained during latency. However, CD8(+) T cells specific for subdominant epitopes lose functionality, whereas those specific for the immunodominant epitope exhibit increased functionality in latently infected TG. Furthermore, we show that IL-10 produced by 16.4 ± 2.8% of TG-resident CD4(+) T cells maintains the immunodominance hierarchy in part through selective inhibition of subdominant CD8(+) T cell proliferation. Upon systemic anti-IL-10R Ab treatment, we observed a significant expansion of functional subdominant CD8(+) T cells, resulting in significantly improved protection from viral reactivation. In fact, systemic anti-IL-10R Ab treatment prevented viral reactivation in up to 50% of treated mice. Our results not only demonstrate that HSV-1 reactivation from latency can be prevented by expanding the repertoire of functional TG-resident CD8(+) T cells, but also that IL-10R blockade might have therapeutic potential to reduce or eliminate recurrent herpetic disease.

Recurrent herpetic stromal keratitis in mice, a model for studying human HSK

Herpetic eye disease, termed herpetic stromal keratitis (HSK), is a potentially blinding infection of the cornea that results in over 300,000 clinical visits each year for treatment. Between 1 and 2 percent of those patients with clinical disease will experience loss of vision of the infected cornea. The vast majority of these cases are the result of reactivation of a latent infection by herpes simplex type I virus and not due to acute disease. Interestingly, the acute infection is the model most often used to study this disease. However, it was felt that a recurrent model of HSK would be more reflective of what occurs during clinical disease. The recurrent animal models for HSK have employed both rabbits and mice. The advantage of rabbits is that they experience reactivation from latency absent any known stimulus. That said, it is difficult to explore the role that many immunological factors play in recurrent HSK because the rabbit model does not have the immunological and genetic resources that the mouse has. We chose to use the mouse model for recurrent HSK because it has the advantage of there being many resources available and also we know when reactivation will occur because reactivation is induced by exposure to UV-B light. Thus far, this model has allowed those laboratories using it to define several immunological factors that are important to this disease. It has also allowed us to test both therapeutic and vaccine efficacy.

Interleukin-17 enhanced immunoinflammatory lesions in a mouse model of recurrent herpetic keratitis

Interleukin-17 (IL-17), mainly produced by activated (memory) T cells, has been found in the corneas from herpetic stromal keratitis (HSK) patients. To better understand the role of IL-17 and to optimize fidelity to human recurrent HSK, in this study, we utilized a mouse model of recurrent HSK, examined the expression of IL-17 and Th17 cells, and determine the alterability of virus-induced corneal inflammation after anti-IL-17 antibody treatment during murine recurrent HSK. We found that Th17 cells were obviously up-regulated in both cornea and DLNs of recurrent mice. Peak IL-17 protein present in recurrent cornea in conjunction with peak opacity mediated by CD4(+) T cells. Systemic administration of anti-IL-17 antibody resulted in a diminished severity of corneal opacity, neovascularization, and CD4(+) T cells infiltration compared to control. Anti-IL-17 treatment down-regulated the mRNA and protein levels of TNF-α expression in recurrent corneas, and decreased HSV-specific DTH responses. Our results indicate that elevated IL-17 expression may be involved in the development of recurrent HSK. The likely mechanisms of action for IL-17 are through up-regulating TNF-α expression and promoting HSV-specific DTH responses. Thus, IL-17 might constitute a useful target for therapeutic intervention in recurrent HSK.

Recurrent herpetic stromal keratitis in mice: a model for studying human HSK

Herpes simplex virus 1 (HSV-1) infection of the cornea leads to a potentially blinding disease, termed herpetic stromal keratitis (HSK) that is characterized by lesions of an immunoinflammatory nature. In spite of the fact that HSK typically presents as a recurrent disease due to reactivation of virus which latently infects the trigeminal ganglia, most murine studies of HSK have employed a primary and not recurrent model of the disease. This report documents the several recurrent models of HSK that have been developed and how data generated from these models differs in some important aspects from data generated following primary infection of the cornea. Chief among these differences is the fact that recurrent HSK takes place in the context of an animal that has a preexisting anti-HSV immune response, while primary HSK occurs in an animal that is developing such a response. We will document both differences and similarities that derive from this fundamental difference in these models with an eye towards possible vaccines and therapies that demonstrate promise in treating HSK.

Delayed type hypersensitivity in the pathogenesis of recurrent herpes stromal keratitis

Recurrent herpes stromal keratitis (HSK) is one of the leading causes of blindness in the developed world. Cyokines characteristic of Th1 cells (in particular IFN-γ and IL-2) have been shown to dominate in HSK in addition to mechanisms by nonspecific, antigen-independent effector cells such as neutrophils, basophils, and monocytes. More recently, the migration and maturation of dendritic cells (DC) within the corneal stroma of patients with HSK have been recognized as contributors to recurrent disease, suggesting a role for delayed type hypersensitivity (DTH) in the immunopathogenesis of HSK. The role of DC and DTH in recurrent HSK has not been studied extensively and experimental models of recurrent HSK focusing on DTH as the pathogenesis and viral particles as the triggering antigen may contribute to better understanding of the disease.

Nona-D-arginine amide suppresses corneal cytokines in Pseudomonas aeruginosa keratitis

PURPOSE

Nona-D-arginine (D9R) amide suppressed interleukin 1β production during Pseudomonas aeruginosa corneal infection. The purpose of this study was to determine the cellular disposition of D9R and its effect on other inflammatory mediators induced by infection.

METHODS

Mouse eyes received 5 μL of either phosphate-buffered saline (PBS, pH 7.4) or 100-μM D9R hourly for 5 hours (total of 6 drops per eye) immediately after corneal wounding and infection with 1 × 10 colony-forming units (CFUs) of P. aeruginosa strain PAO1. At 6, 12, and 24 hours postinfection, eyes were scored on a scale of 0 (normal eye) to +4 (corneal perforation). After scoring, mice were killed and eyes enucleated. Whole eyes were used for determining viable CFUs per eye. Corneas were excised for quantitation of tumor necrosis factor α, interferon γ, interleukin 10, and granulocyte-macrophage colony-stimulating factor. The fate of D9R in cells was determined using a labeled peptide.

RESULTS

Eyes treated with D9R had significantly lower disease scores (P ≤ 0.001) and fewer CFUs (P ≤ 0.01) than those in PBS-treated eyes. No corneal cytokines were detected in any D9R-treated eyes. In contrast, beginning at 12 hours postinfection, increasing amounts of tumor necrosis factor alpha, interleukin 10, and granulocyte-macrophage colony-stimulating factor were detectible in corneas of PBS-treated eyes. Within 60 minutes, D9R accumulated in the cell nucleus and nucleolus and remained for over 24 hours.

CONCLUSION

D9R reduces the severity of P. aeruginosa ocular infection in part by reducing bacterial burden and in part by controlling a destructive proinflammatory response. D9R might be a useful alternative to steroids in treating other inflammation-mediated pathologies of the eye.

A novel p40-independent function of IL-12p35 is required for progression and maintenance of herpes stromal keratitis

PURPOSE. Interleukin (IL)-12p40 can couple with IL-12p35 or p19 chains to form the molecules IL-12p70 and IL-23, respectively, which promote T(H)1 cytokine responses. IL-12p35 can bind to EBI3 to form the anti-inflammatory molecule IL-35, but a proinflammatory function of IL-12p35 independent of IL-12p40 has not been described. Here such a function in a mouse model of herpes stromal keratitis (HSK), a CD4(+) T(H)1 cell-dependent corneal inflammation, is demonstrated. METHODS. Corneas of wild-type (WT), IL-12p40(-/-), IL-12p35(-/-), and IL-12p35(-/-)p40(-/-) (double knockout) mice were infected with the RE strain of HSV-1, and HSK was monitored based on corneal opacity, neovascularization, leukocytic infiltrate, and cytokine/chemokine levels. RESULTS. All mouse strains developed moderate HSK by 11 days after infection (dpi). However, from 11 to 21 dpi, HSK progressed in WT and IL-12p40(-/-) mice but regressed in IL-12p35(-/-) and IL-12p35(-/-)p40(-/-) mice. HSK regression was characterized by reductions in neutrophils and CD4(+) T cells and attenuation of blood vessels, which was associated with reduced levels of the chemokines KC (CXCL3), Mip-2 (CXCL2), and MCP-1 (CCL2) and the angiogenic factor vascular endothelial growth factor. CONCLUSIONS. HSK development does not require IL-12p40 and is thus independent of IL-12p70 and IL-23. However, late HSK progression does require a previously unrecognized IL-12p40-independent, proinflammatory function of IL-12p35.

Interferon gamma is not required for recurrent herpetic stromal keratitis

The role that interferon-gamma (IFNgamma) plays during herpetic stromal keratitis (HSK) has not been definitively determined. In primary HSK most reports suggest that IFNgamma may help control viral replication and contribute to corneal pathology. However, its role in recurrent HSK has not been directly addressed. The present study addresses its role in recurrent HSK by comparing HSK in latently infected normal and IFNgamma gene knockout (GKO) on the C57BL/6 background. We initially evaluated HSK following primary infection and observed that GKO mice had higher tear film virus titers, but virtually identical ocular disease as normal mice. In contrast, following reactivation of latent virus, GKO mice had a greater incidence and severity of opacity, neovascularization, and blepharitis. Interestingly, the incidence of reactivation after UV-B exposure was equivalent in GKO and normal mice, but virus shedding was increased in the GKO groups. We also observed diminished delayed-type hypersensitivity responses in GKO mice, as expected. These data indicate that IFNgamma is important for the control of virus replication in both primary and recurrent ocular HSV infection in C57BL/6 mice. The enhanced recurrent disease seen in GKO mice may be the result of increased viral titers and persistence in these mice which act to prolong the stimulation of an inflammatory response.

Lactoferrin Glu561Asp polymorphism is associated with susceptibility to herpes simplex keratitis

Lactoferrin plays an important role in the defense against infections, including herpes simplex virus (HSV) keratitis. We studied the impact of three single nucleotide polymorphisms in the human lactoferrin gene on the susceptibility to HSV infections of the eye and the severity of such infections. Lactoferrin gene polymorphisms were determined by PCR combined with restriction fragment length analysis in 105 HSV keratitis patients and 145 control subjects. Bilateral tear samples were harvested from 50 patients and 40 healthy controls and tear lactoferrin concentrations were determined by ELISA. Patients' records were used to acquire information about the severity of the HSV keratitis. The frequencies of the Glu561Asp polymorphism, but not those of the Ala11Thr and Lys29Arg polymorphisms, differed significantly between patients and control subjects with an under-representation of the Asp561 allele in the patient group. Furthermore, the values for best corrected visual acuity, frequency of recurrences since onset, and average duration of clinical episodes did not differ among patients with various lactoferrin genotypes. In addition, tear lactoferrin concentrations were the same in patients with HSV keratitis and healthy controls and also did not differ among patients with various lactoferrin genotypes. Lactoferrin Glu561Asp polymorphism is associated with the susceptibility to HSV keratitis with a protective role for lactoferrin variants comprising Asp561. However, no beneficial effects of this lactoferrin variant on the clinical outcome of ocular HSV keratitis were noted.