Nanohydroxyapatite Coating Attenuates Fibrotic and Immune Responses to Promote Keratoprosthesis Biointegration in Advanced Ocular Surface Disorders.

Keratoprosthesis (KPro) implantation is frequently the only recourse for patients with severe corneal disease. However, problems arise due to inadequate biointegration of the KPro, particularly the PMMA optical cylinder, such as tissue detachment, tissue melting, or eye-threatening infection in the interface. Here, using the AuroKPro as a model prosthesis, a surface functionalization approach─coating the optical cylinder with nanohydroxyapatite (nHAp)─was trialed in rabbit eyes with and without a proceeding chemical injury. In chemically injured eyes, which simulated total limbal epithelial stem cell deficiency, clear benefits were conferred by the coating. The total modified Hackett-McDonald score and area of tissue apposition differences 12 weeks after implantation were 5.0 and 22.5%, respectively. Mechanical push-in tests revealed that 31.8% greater work was required to detach the tissues. These differences were less marked in uninjured eyes, which showed total score and tissue apposition differences of 2.5 and 11.5%, respectively, and a work difference of 23.5%. The improved biointegration could be contributed by the attenuated expression of fibronectin (p = 0.036), collagen 3A1 (p = 0.033), and α-smooth muscle actin (p = 0.045)─proteins typically upregulated during nonadherent fibrous capsule envelopment of bioinert material─adjacent to the optical cylinders. The coating also appeared to induce a less immunogenic milieu in the ocular surface tissue, evidenced by the markedly lower expression of tear proteins associated with immune and stimulus responses. Collectively, the level of these tear proteins in eyes with coated prostheses was 1.1 ± 13.0% of naïve eyes: substantially lower than with noncoated KPros (246.5 ± 79.3% of naïve, p = 0.038). Together, our results indicated that nHAp coating may reduce the risk of prosthesis failure in severely injured eyes, which are representative of the cohort of KPro patients.

IL-36γ Augments Ocular Angiogenesis by Promoting the Vascular Endothelial Growth Factor-Vascular Endothelial Growth Factor Receptor Axis.

Prevention of inflammatory angiogenesis is critical for suppressing chronic inflammation and inhibiting inflammatory tissue damage. Angiogenesis is particularly detrimental to the cornea because pathologic growth of new blood vessels can lead to marked vision impairment and even loss of vision. The expression of proinflammatory cytokines by injured tissues exacerbates the inflammatory cascade, including angiogenesis. IL-36 cytokine, a subfamily of the IL-1 superfamily, consists of three proinflammatory agonists, IL-36α, IL-36ß, and IL-36γ, and an IL-36 receptor antagonist (IL-36Ra). Data from the current study indicate that human vascular endothelial cells constitutively expressed the cognate IL-36 receptor. The current investigation, for the first time, characterized the direct contribution of IL-36γ to various angiogenic processes. IL-36γ up-regulated the expression of vascular endothelial growth factors (VEGFs) and their receptors VEGFR2 and VEGFR3 by human vascular endothelial cells, suggesting that IL-36γ mediates the VEGF-VEGFR signaling by endothelial cells. Moreover, by using a naturally occurring antagonist IL-36Ra in a murine model of inflammatory angiogenesis, this study demonstrated that blockade of endogenous IL-36γ signaling results in significant retardation of inflammatory angiogenesis. The current investigation on the proangiogenic function of IL-36γ provides novel evidence of the development of IL-36γ-targeting strategies to hamper inflammatory angiogenesis.

Analysis of Immune Cells on Donor Corneal Endothelium After Corneal Transplantation Using the HRT-Rostock Cornea Module.

PURPOSE: The aim of this study was to investigate the immune cells on corneal endothelium of the graft in patients who underwent penetrating keratoplasty (PK), Descemet-stripping endothelial keratoplasty (DSEK), and Descemet membrane endothelial keratoplasty (DMEK). METHODS: A total of 43 eyes of 43 patients who underwent PK (17 eyes), DSEK (13 eyes), and DMEK (13 eyes) and who did not show any sign of graft rejection were recruited for the study. Patients who underwent cataract surgery (26 eyes) served as controls. Immune cells on the corneal endothelium were examined with laser in vivo confocal microscopy. The associations between the corneal endothelial cell density, type of keratoplasty, aqueous flare, repeated keratoplasty, and time after surgery versus the density of immune cells were investigated. RESULTS: In vivo confocal microscopy visualized similar numbers of immune cells on the corneal endothelium in the PK, DSEK, and DMEK groups, whereas no immune cells were observed in any of the control patients. The numbers of immune cells tended to be higher in regraft eyes in the PK group (P = 0.00221) and in the DSEK group (P = 0.168) than those in the primary graft eyes. No significant association was found between the density of immune cells and corneal endothelial cell density in the PK, DSEK, and DMEK groups. CONCLUSIONS: Immune cells were observed to a similar extent in the eyes of PK, DSEK, and DMEK subjects even in the absence of any clinical sign of immune rejection. A further prospective longitudinal study will evaluate the effect of immune cells on long-term graft survival and the risk for graft rejection.

The cornea IV immunology, infection, neovascularization, and surgery chapter 1: Corneal immunology.

PURPOSE: of Review: This review offers an informed and up-to-date insight on the immune profile of the cornea and the factors that govern the regulation of such a unique immune environment. SUMMARY: The cornea is a unique tissue that performs the specialized task of allowing light to penetrate for visual interpretation. To accomplish this, the ocular surface requires a distinct immune environment that is achieved through unique structural, cellular and molecular factors. Not only must the cornea be able to fend off invasive infectious agents but also control the inflammatory response as to avoid collateral, and potentially blinding damage; particularly of post-mitotic cells such as the corneal endothelium. To combat infections, both innate and adaptive arms of the inflammatory immune response are at play in the cornea. Dendritic cells play a critical role in coordinating both these responses in order to fend off infections. On the other side of the spectrum, the ocular surface is also endowed with a variety of anatomic and physiologic components that aid in regulating the immune response to prevent excessive, potentially damaging, inflammation. This attenuation of the immune response is termed immune privilege. The balance between pro and anti-inflammatory reactions is key for preservation of the functional integrity of the cornea. RECENT FINDINGS: The understanding of the molecular and cellular factors governing corneal immunology and its response to antigens is a growing field. Dendritic cells in the normal cornea play a crucial role in combating infections and coordinating the inflammatory arms of the immune response, particularly through coordination with T-helper cells. The role of neuropeptides is recently becoming more highlighted with different factors working on both sides of the inflammatory balance.

Roles of Epithelial and Mesenchymal TRP Channels in Mediating Inflammatory Fibrosis.

The maintenance of normal vision is dependent on preserving corneal transparency. For this to occur, this tissue must remain avascular and its stromal architecture needs to be retained. Epithelial transparency is maintained provided the uppermost stratified layers of this tissue are composed of terminally differentiated non-keratinizing cells. In addition, it is essential that the underlying stromal connective tissue remains avascular and scar-free. Keratocytes are the source of fibroblasts that are interspersed within the collagenous framework and the extracellular matrix. In addition, there are sensory nerve fibers whose lineage is possibly either neural crest or mesenchymal. Corneal wound healing studies have been undertaken to delineate the underlying pathogenic responses that result in the development of opacification following chemical injury. An alkali burn is one type of injury that can result in severe and long- lasting losses in ocular transparency. During the subsequent wound healing process, numerous different proinflammatory cytokines and proteolytic enzymes undergo upregulation. Such increases in their expression levels induce maladaptive expression of sustained stromal inflammatory fibrosis, neovascularization, and losses in the smooth optical properties of the corneal outer surface. It is becoming apparent that different transient receptor potential channel (TRP) isoforms are important players in mediating these different events underlying the wound healing process since injury upregulates both their expression levels and functional involvement. In this review, we focus on the involvement of TRPV1, TRPA1 and TRPV4 in mediating some of the responses that underlie the control of anterior ocular tissue homeostasis under normal and pathological conditions. They are expressed on both different cell types throughout this tissue and also on corneal sensory nerve endings. Their roles have been extensively studied as sensors and transducers of environmental stimuli resulting from exposure to intrinsic modulators and extrinsic ligands. These triggers include alteration of the ambient temperature and mechanical stress, etc., that can induce pathophysiological responses underlying losses in tissue transparency activated by wound healing in mice losses in tissue transparency. In this article, experimental findings are reviewed about the role of injury-induced TRP channel activation in mediating inflammatory fibrotic responses during wound healing in mice.

Use of Panel-Reactive Antibody Testing in the Planning and Management of Ocular Surface Stem Cell Transplantation.

PURPOSE: Panel-reactive antibody (PRA) testing has been widely adopted in solid organ transplantation for risk assessment in potential allograft recipients but has not been studied in the context of ophthalmic transplantation. The purpose of this study is to evaluate outcomes in patients undergoing ocular surface stem cell transplantation (OSST) for limbal stem cell deficiency (LSCD) relative to preoperative PRA level. METHODS: This is retrospective chart review of all eyes with documented PRA level that underwent OSST for LSCD between May 2000 and March 2019 at a single institution. Eyes with stable ocular surface but <1 year of follow-up and eyes without updated PRA before repeat OSST were excluded. Eyes were grouped by PRA <80% and ≥80%. The primary outcome was ocular surface failure, whereas the secondary outcome was clinical allograft rejection. RESULTS: Sixty-nine surgeries met inclusion criteria, consisting of 54 living-related conjunctival limbal allografts, 5 keratolimbal allografts, and 10 combined living-related conjunctival limbal allografts/keratolimbal allografts (Cincinnati procedure). The most common etiologies for LSCD were aniridia (33%), chemical/thermal injury (28%), and contact lens associated (14%). Surface failure occurred in 5 of 12 eyes (58%) with PRA ≥80% versus 12 of 57 eyes (21%) with PRA <80% (P = 0.01). The relative risk for surface failure with PRA ≥80% was 2.8 [confidence interval (CI), 1.38-5.55]. There was no significant difference in acute rejection (P = 1). CONCLUSIONS: Pretransplant PRA level is an important prognostic factor for ocular surface stability in eyes undergoing OSST for LSCD, with implications for donor selection, perioperative management, and systemic immunosuppression.

ISOPT Clinical Hot Topic Panel Discussion on Cornea Anterior Segment Disease.

The cornea and its adnexa pose a unique situation of a tightly defined set of requirements for its function. This includes: transparency, perfect built to obtain appropriate refractive power, protective barrier from microbial invaders. Moreso, the cornea also endures extreme external physical conditions (temperature, high and low humidity, winds and alike). All these functions are maintained while preserving a constant state of homogenous wetting. Toward that end the cornea is equipped with an elaborated network of sensory neural network. While enabling the blinking reflex and maintaining the physiological steady state of wetting, this neural network also makes the cornea prone to the discomfort that with or without associated changes seen on medical examination. ISOPT Clinical 2018 discussion touched upon this hypercomplex situation, addressing the role of inflammation and its resulting discomfort in dry eye conditions. The discussion also engulfed the emerging neuropathic pain syndrome that is recently gaining more attention. Another related topic was the utilization of autologous serum tears and its ability to provide amelioration to desperate patients. Finally, the panel discussed the issue of treating corneal infection, including when and how to utilize steroids in the course of therapy. We assume the reader will find interest in this discussion that directly addresses issues seen day in and day out in our busy clinics.

Corneal vortex keratopathy in childhood-onset systemic lupus erythematosus (c-SLE).

OBJECTIVE: To describe the prevalence and risk factors associated with corneal vortex keratopathy in a childhood-onset systemic lupus erythematosus (c-SLE) cohort. MATERIAL AND METHODS: Consecutive outpatients with c-SLE were evaluated by a pediatric ophthalmologist and pediatric rheumatologist in an outpatient clinic setting in an urban Children's Hospital. Demographic, clinical, laboratory, and disease characteristics were documented for each patient. Cumulative drug dosage, Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), and Systemic Lupus Erythematosus International Collaborating Clinics/American College of Rheumatology damage index (SLICC/ACR-DI) scores were calculated. RESULTS: A total of 76 c-SLE patients (61 (80.26%) females; mean age = 17.9 (SD ± 3.07)) were included. Ophthalmologic abnormalities were observed in 36 (47.36%) patients of which 16 (21.10%) had corneal vortex keratopathy (p = 0.03). c-SLE patients with corneal vortex keratopathy were all female. We did not observe any additional clinical, laboratory, or treatment feature associated with corneal vortex keratopathy. DISCUSSION: We observed a high prevalence of corneal vortex keratopathy in female c-SLE. We hypothesize that this finding may be an initial, dose-related toxicity due to antimalarial use. Follow-up studies are necessary to determine if these changes are an early predictor of retinal toxicity due to antimalarial in c-SLE. KEY POINTS: • Corneal vortex keratopathy was frequently observed in female patients with c-SLE on a chloroquine medication. • Corneal vortex keratopathy may be an early marker of chloroquine retinopathy.

Corneal Manifestations of Systemic Sclerosis.

Purpose: Corneal involvement in systemic sclerosis (SSc) is rare, but due to rich collagen composition cornea is especially vulnerable to connective tissue diseases. Therefore, our aim was to evaluate corneal parameters of SSc patients. Methods: The study included 32 SSc patients and 39 control subjects with no ocular symptoms or ocular surface disorders. All study participants underwent Pentacam evaluation and objective signs of dry eye disease (DED), and clinical parameters were evaluated. Results: All pachymetric values, most of the corneal front surface, corneal volume, as well as anterior chamber depth measurements were significantly lower in the SSc group than in the control group (p < 0.05). Significant negative correlation was found between corneal parameters and age on the one hand, and disease duration on the other. Conclusions: Early recognition of corneal impairment, a possible extraintestinal manifestation of SSc, should be included in the check-up of the disease in order to reduce sight-threatening complications.

The feasibility and efficacy of preparing porcine Descemet's membrane endothelial keratoplasty (DMEK) grafts by two techniques: An ex-vivo investigation for future xeno-DMEK.

BACKGROUND: Descemet's membrane endothelial keratoplasty (DMEK) might be a promising technique for future xeno-corneal transplantation due to its ultrathin graft, extremely low rejection occurrence, suture-free graft fixation, and minimal immunosuppressive regime usage. The aim of this study is to explore the feasibility and efficacy of preparing porcine DMEK grafts by 2 techniques and investigate the graft ultrastructure. METHODS: Two mainstream techniques, mechanical stripping technique and liquid bubble technique, were modified to prepare the porcine DMEK grafts. In all, 40 corneas harvested from WZS-pigs (aged 10-12 months) were subjected to the techniques (20 corneas for each technique). The success rate, time consumption, and endothelial cell density (ECD) before and after preparation were recorded and compared between the 2 techniques. And the ultrastructure of the porcine DEMK graft was investigated by transmission electron microscope. In addition, 9 WZS-pigs with different ages were sacrificed to explore the correlation between the thickness of Descemet's membrane and porcine age. RESULTS: After modifying several technical details, the porcine DMEK grafts were successfully prepared by either mechanical stripping technique or liquid bubble technique, and the mark technique to distinguish the 2 sides of the graft was also explored. In all, 13 DMEK grafts (65%) were prepared successfully by the mechanical stripping technique, whereas 14 successful cases (70%) were prepared by the liquid bubble technique. The success rates between the 2 techniques showed no significant difference (P = .847). However, the mechanical stripping technique was significantly time-consuming when compared with the liquid bubble technique (P < .0001). The ECDs reduced significantly after preparation no matter what techniques were used (P < .0001), but the ECD after the liquid bubble preparation was significantly higher than the ECD after mechanical stripping (P = .032). The ECD reduction positively correlated to the time consumption for both mechanical stripping technique (P = .0014, R2  = 0.621) and liquid bubble technique (P = .013, R2  = 0.412). The ultrastructure showed the graft was comprised of stromal residuals, non-banded layer, and endothelial layer. Unlike human Descemet's membrane (DM), anterior banded layer was not observed. The thickness of porcine DM increased with the age, and a significant positive correlation between them was found (P < .0001, R2  = 0.949), and the predict equation was Y = 0.3764*X + 7.378 (Y indicates the thickness, whereas X indicates the age). CONCLUSIONS: Porcine DMEK grafts could be prepared either by mechanical stripping technique or liquid bubble technique, and the liquid bubble technique seems superior over the mechanical stripping technique regarding time consumption and ECD preservation. Although there are several technical barriers to overcome, xeno-DMEK might be a promising direction for future xeno-corneal transplantation.

Corneal Epithelial Cells Exhibit Myeloid Characteristics and Present Antigen via MHC Class II.

Purpose: To explore the impact of ocular surface insults on the immunomodulatory capacity and phenotype of corneal epithelial cells (CECs) with a focus on epithelial-mesenchymal transition (EMT). Methods: Corneas were harvested from mice 6 days following scratch injury, ragweed pollen-induced allergy, or herpes simplex virus type 1 (HSV-1) infection and compared to healthy tissue controls. Corneas were enzymatically digested and CECs phenotypically characterized using flow cytometry. CECs were defined as epithelial cell adhesion molecule (EpCAM)-positive CD45-negative cells. CECs were assessed by PCR to evaluate EMT-associated transcripts. Recombinant HSV-1 and transgenic mice were utilized to investigate the role of vascular endothelial growth factor A (VEGFA) on the phenotype observed. The immunomodulatory potential of CECs was assessed in coculture assays with ovalbumin-specific CD4 T cells. Results: Ectopic expression of classic "myeloid" antigens Ly6G, CCR2, and CX3CR1 was identified in CEC subsets from all groups with evidence supporting an underlying partial EMT event resulting from loss of cell-cell contacts. Corneal HSV-1 infection induced Ly6C expression and major histocompatibility complex (MHC)-II upregulation in CECs through a VEGFA-linked mechanism. These Ly6C+ MHC-II+ CECs were found to function as amateur antigen-presenting cells and induced CD4 T cell proliferation in vitro. Conclusions: This study characterizes a novel immunomodulatory CEC phenotype with possible implications for immune privilege, chronic inflammation, and tissue fibrosis. Moreover, the identification of CECs masquerading with multiple "myeloid" antigens warrants careful evaluation of flow cytometry data involving corneal digests.

Ocular manifestations of autoimmune polyendocrinopathy syndrome type 1.

PURPOSE OF REVIEW: The ocular manifestations in autoimmune polyendocrinopathy syndrome type 1 (APS1) are frequent and have a poor prognosis. The phenotype of these APS1-associated ocular features have been recently characterized in molecularly confirmed patients with APS1. RECENT FINDINGS: Keratopathy and retinopathy can be severe manifestations of APS1. Heterogeneous corneal involvement can be observed, ranging from minimal superficial punctate staining to severe stromal scarring with deep corneal neovascularization. This phenotypic heterogeneity, observed even in patients with identical AIRE mutations, is suggestive of a poor genotype-phenotype correlation. Similarly, in patients with retinopathy, peripheral pigmentary changes are noted in all cases, yet with heterogeneous severity, ranging from isolated patchy atrophy of the retinal pigment epithelium to a retinitis pigmentosa-like fundus. Macular atrophy with vision loss is found in most cases. The severity of ophthalmic findings is uncorrelated to that of systemic manifestations. An autoimmune origin with specific autoantibodies directed against corneal and/or retinal autoantigens is the main mechanism believed to be responsible for the ocular manifestations of APS1. SUMMARY: Progressive keratopathy and/or retinopathy can lead to severe visual loss and pain in patients with APS1. Although no treatment has shown efficacy regarding the APS1-associated ocular manifestations, ophthalmologic examinations are recommended in these patients.

IL-6 Contributes to Corneal Nerve Degeneration after Herpes Simplex Virus Type I Infection.

Herpes simplex virus type 1 (HSV-1) is a leading cause of neurotrophic keratitis characterized by decreased corneal sensation because of damage to the corneal sensory fibers. We and others have reported regression of corneal nerves during acute HSV-1 infection. To determine whether denervation is caused directly by the virus or indirectly by the elicited immune response, mice were infected with HSV-1 and topically treated with dexamethasone (DEX) or control eye drops. Corneal sensitivity was measured using a Cochet-Bonnet esthesiometer and nerve network structure via immunohistochemistry. Corneas were assessed for viral content by plaque assay, leukocyte influx by flow cytometry, and content of chemokines and inflammatory cytokines by suspension array. DEX significantly preserved corneal nerve structure and sensitivity on infection. DEX reduced myeloid and T-cell populations in the cornea and did not affect viral contents at 4 and 8 days post infection. The elevated protein contents of chemokines and inflammatory cytokines on infection were greatly suppressed by DEX. Subconjunctival delivery of neutralizing antibody against IL-6 to infected mice resulted in partial preservation of corneal nerve structure and sensitivity. Our study supports a role for the immune response, but not local virus replication in the development of HSV-1-induced neurotrophic keratitis. IL-6 is one of the factors produced by the elicited inflammatory response to HSV-1 infection contributing to nerve regression.

Both CD8+ and CD4+ T Cells Contribute to Corneal Clouding and Viral Clearance following Vaccinia Virus Infection in C57BL/6 Mice.

UNLABELLED: Vaccinia virus (VACV) keratitis is a serious complication following smallpox vaccination and can lead to blindness. The pathological mechanisms involved in ocular VACV infection are poorly understood. Previous studies have used rabbits, but the lack of immune reagents and transgenic or knockout animals makes them less suitable for mechanistic studies. We report that infection of C57BL/6 mice with 1 × 10(7) PFU of vaccinia virus strain WR results in blepharitis, corneal neovascularization, and stromal keratitis. The DryVax strain of VACV was completely attenuated. Infection required corneal scarification and replication-competent virus, and the severity of ocular disease was similar in 4- to 6-week-old and 1-year-old mice. Viral titers peaked at approximately 1 × 10(6) PFU on day 5 postinfection, and virus had not cleared by day 13 postinfection. Neutrophils were found in the peripheral cornea on day 1 after infection and then declined, followed by infiltration of both CD4(+) and CD8(+) T cells, which remained peripheral throughout the infection. Blood vessel growth extended 2 to 5 mm into the cornea from the limbus. Infection of CD4(-/-), CD8(-/-), or antibody-depleted mice resulted in similar disease severity and corneal clouding, indicating that both T-cell subsets were involved in the immunopathological response. Depletion of both CD4(+) and CD8(+) T cells resulted in significantly more severe disease and failure to clear the virus. On the basis of our results, the pathology of VACV keratitis is significantly different from that of herpes simplex virus keratitis. Further studies are likely to reveal novel information regarding virulence and immune responses to viral ocular infection. IMPORTANCE: Potentially blinding eye infections can occur after vaccination for smallpox. Very little is known about the pathological mechanisms that are involved, and the information that is available was generated using rabbit models. The lack of immunological reagents for rabbits makes such studies difficult. We characterized a mouse model of vaccinia virus ocular disease using C57BL/6 mice and strain WR and show that both CD4(+) and CD8(+) T-cell subsets play a role in the blinding eye disease and in controlling virus replication. On the basis of these results, vaccinia virus keratitis is significantly different from herpes simplex virus keratitis, and further studies using this model should generate novel insights into immunopathological responses to viral ocular infection.

Suppression of Allograft Rejection with Soluble VEGF Receptor 2 Chimeric Protein in a Mouse Model of Corneal Transplantation.

When a transparent cornea becomes opaque due to infectious diseases, trauma, or ophthalmic surgery, the impaired cornea is replaced with a donor cornea to improve visual function. In this corneal transplantation, the graft survival rate is comparatively high, partly because of lacking vascular and lymphatic vessel in cornea. However, the transplanted corneas sometimes become opaque if allograft rejection occurs. Suppression of allograft rejection is critical for favorable outcomes of corneal transplantation. The essential effects of endogenous monomeric soluble vascular endothelial growth factor receptors (VEGFRs) 1 and 2 have been reported in corneal angiogenesis and lymphangiogenesis. This study investigated the effects of dimeric soluble VEGFR2/Fc chimera protein on corneal allograft rejection for future clinical application. Allogeneic full-thickness corneal transplantation was performed in C57BL/6 to BALB/c mice. The recipients were treated by intrastromal injection of soluble VEGFR1/Fc chimera (sR1/Fc group), soluble VEGFR2/Fc chimera (sR2/Fc group), or human IgG1/Fc protein (IgG/Fc group) at 0, 7, and 14 days after surgery. Both hemangiogenesis and lymphangiogenesis were significantly suppressed in the corneas of the sR2/Fc group compared with the IgG/Fc group. All grafts failed due to corneal wound rupture in the sR1/Fc group. In the sR2/Fc group, respective donor-derived MHC class II(+)/CD11c(+) cells and CD11b-positive macrophage infiltration were reduced in the DLNs and the corneas showing a negative delayed-type hypersensitivity, compared with the IgG/Fc group. Our findings demonstrate that soluble VEGFR2/Fc chimera protein efficiently suppresses corneal allo-rejection, while reducing hemangiogenesis and lymhangiogenesis, and immune-competent cell-trafficking and may be a powerful tool for corneal allograft survival.

Laser Scanning In Vivo Confocal Microscopy of Clear Grafts after Penetrating Keratoplasty.

PURPOSE: To evaluate the changes of keratocytes and dendritic cells in the central clear graft by laser scanning in vivo confocal microscopy after penetrating keratoplasty (PK). METHODS: Thirty adult subjects receiving PK at Shandong Eye Institute and with clear grafts and no sign of immune rejection after surgery were recruited into this study, and 10 healthy adults were controls. The keratocytes and dendritic cells in the central graft were evaluated by laser scanning confocal microscopy, as well as epithelium cells, keratocytes, corneal endothelium cells, and corneal nerves (especially subepithelial plexus nerves). RESULTS: Median density of subepithelial plexus nerves, keratocyte density in each layer of the stroma, and density of corneal endothelium cells were all lower in clear grafts than in controls. The dendritic cells of five (16.7%) patients were active in Bowman's membrane and stromal membrane of the graft after PK. CONCLUSIONS: Activated dendritic cells and Langerhans cells could be detected in some of the clear grafts, which indicated that the subclinical stress of immune reaction took part in the chronic injury of the clear graft after PK, even when there was no clinical rejection episode.

Immunologic Mediators in Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis.

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are a spectrum of T-cell mediated immune disorders. While the contributory mechanisms leading to the apoptosis of epidermal cells in SJS/TEN remain unproven, the keratinocyte apoptosis seen in SJS/TEN is thought to occur through the T-cell mediated Fas-Fas ligand (FasL), perforin/granzyme B, and other immune mediators. Most recently, emphasis has been placed on the granulysin pathway as being the primary mediator of apoptosis and widespread epidermal necrosis in SJS/TEN. This article aims to review the proposed mechanisms by which these pathways work and the immunomodulatory therapies that have been developed in an attempt to target them.

Evaluation of Effect of Topical Tacrolimus Treatment on Herpetic Stromal Keratitis in a Rat Model.

OBJECTIVES: To investigate the effectiveness of topical tacrolimus treatment on herpetic stromal keratitis (HSK) in a rat model. METHODS: The development of HSK was monitored for 14 days after the inoculation of rats with herpes simplex type 1 virus. Rats that developed HSK were divided into four groups as follows: (1) topical antiviral treatment (control), (2) topical antiviral and 1% prednisolone acetate, (3) topical antiviral and 0.03% tacrolimus ointment, and (4) topical antiviral plus 0.1% tacrolimus ointment. After 14 days of treatment, the severity levels of HSK were scored and compared with the levels before the treatment. The expression of CD3, CD4, and CD8 was evaluated by flow cytometry. The development of the disease was evaluated clinically and histologically. RESULTS: Significant improvement in vascularization was observed in the groups with the drug treatment in addition to the antiviral agent (P<0.05), but there was no obvious difference within groups 2, 3, and 4 in the vascularization severity. The regression of corneal edema was 8.05%±6% in group 1, 25.17%±14.55% in group 2 (P=0.01), 36.40%±21.69% in group 3 (P=0.03), and 46.39%±14.96% in group 4 (P=0.00). A significant decrease in the number of inflammatory cells in the groups with the drug treatment was evaluated by immunohistochemical staining and confirmed by flow cytometry analysis. CONCLUSIONS: Topical tacrolimus treatment caused a significant decrease in corneal vascularization accompanied by a lower number of inflammatory cells in the experimental HSK corneal edema model. Therefore, topical tacrolimus has the potential to be used in the treatment of HSK.