Cornea

Chen Y, Chauhan SK, Tan X, Dana R. Interleukin-7 and -15 maintain pathogenic memory Th17 cells in autoimmunity. J Autoimmun 2017;77:96-103.Abstract

Th17 cells are principal mediators of many autoimmune conditions. Recently, memory Th17 cells have been revealed as crucial in mediating the chronicity of various refractory autoimmune disorders; however, the underlying mechanisms maintaining memory Th17 cells have remained elusive. Here, using a preclinical model of ocular autoimmune disease we show that both IL-7 and IL-15 are critical for maintaining pathogenic memory Th17 cells. Neutralization of these cytokines leads to substantial reduction of memory Th17 cells; both IL-7 and IL-15 provide survival signals via activating STAT5, and IL-15 provides additional proliferation signals via activating both STAT5 and Akt. Topical neutralization of ocular IL-7 or IL-15 effectively reduces memory Th17 cells at the inflammatory site and draining lymphoid tissues, while topical neutralization of IL-17 alone, the major pathogenic cytokine secreted by Th17 cells, does not diminish memory Th17 cells at the draining lymphoid tissues. Our results suggest that the effective removal of pathogenic memory Th17 cells via abolishing environmental IL-7 or IL-15 is likely to be a novel strategy in the treatment of autoimmune diseases.

Han K-Y, Tran JA, Chang J-H, Azar DT, Zieske JD. Potential role of corneal epithelial cell-derived exosomes in corneal wound healing and neovascularization. Sci Rep 2017;7:40548.Abstract

Specific factors from the corneal epithelium underlying the stimulation of stromal fibrosis and myofibroblast formation in corneal wound healing have not been fully elucidated. Given that exosomes are known to transfer bioactive molecules among cells and play crucial roles in wound healing, angiogenesis, and cancer, we hypothesized that corneal epithelial cell-derived exosomes may gain access to the underlying stromal fibroblasts upon disruption of the epithelial basement membrane and that they induce signaling events essential for corneal wound healing. In the present study, exosome-like vesicles were observed between corneal epithelial cells and the stroma during wound healing after corneal epithelial debridement. These vesicles were also found in the stroma following anterior stromal keratectomy, in which surgical removal of the epithelium, basement membrane, and anterior stroma was performed. Exosomes secreted by mouse corneal epithelial cells were found to fuse to keratocytes in vitro and to induce myofibroblast transformation. In addition, epithelial cell-derived exosomes induced endothelial cell proliferation and ex vivo aortic ring sprouting. Our results indicate that epithelial cell-derived exosomes mediate communication between corneal epithelial cells and corneal keratocytes as well as vascular endothelial cells. These findings demonstrate that epithelial-derived exosomes may be involved in corneal wound healing and neovascularization, and thus, may serve as targets for potential therapeutic interventions.

English JT, Norris PC, Hodges RR, Dartt DA, Serhan CN. Identification and Profiling of Specialized Pro-Resolving Mediators in Human Tears by Lipid Mediator Metabolomics. Prostaglandins Leukot Essent Fatty Acids 2017;117:17-27.Abstract

Specialized pro-resolving mediators (SPM), e.g. Resolvin D1, Protectin D1, Lipoxin A₄, and Resolvin E1 have each shown to be active in ocular models reducing inflammation. In general, SPMs have specific agonist functions that stimulate resolution of infection and inflammation in animal disease models. The presence and quantity of SPM in human emotional tears is of interest. Here, utilizing a targeted LC-MS-MS metabololipidomics based approach we document the identification of pro-inflammatory (Prostaglandins and Leukotriene B₄) and pro-resolving lipid mediators (D-series Resolvins, Protectin D1, and Lipoxin A₄) in human emotional tears from 12 healthy individuals. SPMs from the Maresin family (Maresin 1 and Maresin 2) were not present in these samples. Principal Component Analysis (PCA) revealed gender differences in the production of specific mediators within these tear samples as the SPMs were essentially absent in these female donors. These results indicate that specific SPM signatures are present in human emotional tears at concentrations known to be bioactive. Moreover, they will help to further appreciate the mechanisms of production and action of SPMs in the eye, as well as their physiologic roles in human ocular disease resolution.

Zhou C, Robert M-C, Kapoulea V, Lei F, Stagner AM, Jakobiec FA, Dohlman CH, Paschalis EI. Sustained Subconjunctival Delivery of Infliximab Protects the Cornea and Retina Following Alkali Burn to the Eye. Invest Ophthalmol Vis Sci 2017;58(1):96-105.Abstract

Purpose: Tumor necrosis factor (TNF)-α is upregulated in eyes following corneal alkali injury and contributes to corneal and also retinal damage. Prompt TNF-α inhibition by systemic infliximab ameliorates retinal damage and improves corneal wound healing. However, systemic administration of TNF-α inhibitors carries risk of significant complications, whereas topical eye-drop delivery is hindered by poor ocular bioavailability and the need for patient adherence. This study investigates the efficacy of subconjunctival delivery of TNF-α antibodies using a polymer-based drug delivery system (DDS). Methods: The drug delivery system was prepared using porous polydimethylsiloxane/polyvinyl alcohol composite fabrication and loaded with 85 μg of infliximab. Six Dutch-belted pigmented rabbits received ocular alkali burn with NaOH. Immediately after the burn, subconjunctival implantation of anti-TNF-α DDS was performed in three rabbits while another three received sham DDS (without antibody). Rabbits were followed with photography for 3 months. Results: After 3 months, the device was found to be well tolerated by the host and the eyes exhibited less corneal damage as compared to eyes implanted with a sham DDS without drug. The low dose treatment suppressed CD45 and TNF-α expression in the burned cornea and inhibited retinal ganglion cell apoptosis and optic nerve degeneration, as compared to the sham DDS treated eyes. Immunolocalization revealed drug penetration in the conjunctiva, cornea, iris, and choroid, with residual infliximab in the DDS 3 months after implantation. Conclusions: This reduced-risk biologic DDS improves corneal wound healing and provides retinal neuroprotection, and may be applicable not only to alkali burns but also to other inflammatory surgical procedures such as penetrating keratoplasty and keratoprosthesis implantation.

Lambiase A, Sullivan BD, Schmidt TA, Sullivan DA, Jay GD, Truitt ER, Bruscolini A, Sacchetti M, Mantelli F. A Two-Week, Randomized, Double-masked Study to Evaluate Safety and Efficacy of Lubricin (150 μg/mL) Eye Drops Versus Sodium Hyaluronate (HA) 0.18% Eye Drops (Vismed®) in Patients with Moderate Dry Eye Disease. Ocul Surf 2017;15(1):77-87.Abstract

PURPOSE: The objective of this clinical trial (NCT02507934) was to assess the efficacy and safety of recombinant human lubricin as compared to a 0.18% sodium hyaluronate (HA) eye drop in subjects with moderate dry eye disease (DED). METHODS: DEWS Grade 2-3 subjects were randomized to use lubricin (N=19, 51.9 ± 11.8 years) or HA (N=20, 61.8 ± 13.3 years). After a saline washout period, subjects administered BID therapy for 7 days, followed by instillation as needed (2-6 drops per eye) for 7 days. Visual analog scale (VAS) including foreign body sensation, burning/stinging, itching, pain, sticky feeling, blurred vision and photophobia were primary outcomes, with secondary endpoints of corneal fluorescein staining, Schirmer test, tear film breakup time (TFBUT), eyelid and conjunctival erythema and number of instillations compared at day 14. RESULTS: The primary endpoint was met. Lubricin supplementation achieved greater than a 72% reduction from baseline in foreign body sensation (P<.013), burning/stinging, pain, sticky feeling (P<.0432), blurred vision (P<.0013), and photophobia (P<.011) in at least one eye. Lubricin also showed significant improvement in fluorescein staining (OD/OS: 43.8%/50.0%, vs. 26.5%/23.3%, P<.0398, P<.0232), TFBUT (P<.010), SANDE frequency (P<.0435), eyelid erythema (P<.004), conjunctival erythema (P<.0013), and instillations (P<.04) as compared to HA. No treatment-related adverse events occurred during the investigation. CONCLUSIONS: Recombinant human lubricin was shown to produce significant improvement in both signs and symptoms of dry eye disease as compared to HA.

Ji YW, Mittal SK, Hwang HS, Chang E-J, Lee JH, Seo Y, Yeo A, Noh H, Lee HS, Chauhan SK, Lee HK. Lacrimal gland-derived IL-22 regulates IL-17-mediated ocular mucosal inflammation. Mucosal Immunol 2017;10(5):1202-1210.Abstract
Inflammatory damage of mucosal surface of the eye is a hallmark of dry eye disease (DED) and, in severe cases, can lead to significant discomfort, visual impairment, and blindness. DED is a multifactorial autoimmune disorder with a largely unknown pathogenesis. Using a cross-sectional patient study and a well-characterized murine model of DED, herein we investigated the immunoregulatory function of interleukin-22 (IL-22) in the pathogenesis of DED. We found that IL-22 levels were elevated in lacrimal fluids of DED patients and inversely correlated with severity of disease. Acinar cells of the lacrimal glands (LGs), not inflammatory immune cells, are the primary source of IL-22, which suppresses inflammation in ocular surface epithelial cells upon desiccating stress. Moreover, loss of function analyses using IL-22 knockout mice demonstrated that IL-22 is essential for suppression of ocular surface infiltration of Th17 cells and inhibition of DED induction. Our novel findings elucidate immunoregulatory function of LG-derived IL-22 in inhibiting IL-17-mediated ocular surface epitheliopathy in DED thus making IL-22 a new relevant therapeutic target.
Inomata T, Mashaghi A, Di Zazzo A, Lee S-M, Chiang H, Dana R. Kinetics of Angiogenic Responses in Corneal Transplantation. Cornea 2017;36(4):491-496.Abstract

PURPOSE: To delineate and compare the kinetics of corneal angiogenesis after high-risk (HR) versus low-risk (LR) corneal transplantation. METHODS: In mice, intrastromal sutures were placed in the recipient graft bed 2 weeks before allogeneic transplantation to induce angiogenesis and amplify the risk of graft rejection. Control (LR) graft recipients did not undergo suture placement, and thus the host bed remained avascular at the time of transplantation. Graft hemangiogenesis and opacity scores were evaluated for 8 weeks by slit-lamp biomicroscopy. Immunohistochemistry was used to measure CD31 (blood vessels) and LYVE-1 (lymphatic vessels) cells. RESULTS: Biphasic kinetics were observed for hemangiogenesis in both HR and LR transplant recipients using clinical and immunohistochemical assessments. The biphasic kinetics were composed of a rise-fall (phase 1) followed by a second rise (phase 2) in the degree of vessels. Compared with LR recipients, HR recipients showed higher hemangiogenesis (whole cornea and graft) throughout 8 weeks. Analyzing grafts revealed sustained presence of lymphatic vessels in HR recipients; however, lymphatic neovessels regressed in LR recipients 2 weeks posttransplantation. In contrast to HR host beds, the LR host bed microenvironment cannot sustain the growth of lymphatic neovessels in allografts, whereas it can sustain continued hemangiogenesis. CONCLUSIONS: The sustained presence of lymphatic vessels in HR host beds can facilitate host immunity against allografts and is likely associated with ongoing higher risk of rejection of these grafts in the long term, suggesting that therapeutic interventions targeting inflammation and lymphatic vessels need to be sustained long term in the HR corneal transplant setting.

Cruzat A, Qazi Y, Hamrah P. In Vivo Confocal Microscopy of Corneal Nerves in Health and Disease. Ocul Surf 2017;15(1):15-47.Abstract

In vivo confocal microscopy (IVCM) is becoming an indispensable tool for studying corneal physiology and disease. Enabling the dissection of corneal architecture at a cellular level, this technique offers fast and noninvasive in vivo imaging of the cornea with images comparable to those of ex vivo histochemical techniques. Corneal nerves bear substantial relevance to clinicians and scientists alike, given their pivotal roles in regulation of corneal sensation, maintenance of epithelial integrity, as well as proliferation and promotion of wound healing. Thus, IVCM offers a unique method to study corneal nerve alterations in a myriad of conditions, such as ocular and systemic diseases and following corneal surgery, without altering the tissue microenvironment. Of particular interest has been the correlation of corneal subbasal nerves to their function, which has been studied in normal eyes, contact lens wearers, and patients with keratoconus, infectious keratitis, corneal dystrophies, and neurotrophic keratopathy. Longitudinal studies have applied IVCM to investigate the effects of corneal surgery on nerves, demonstrating their regenerative capacity. IVCM is increasingly important in the diagnosis and management of systemic conditions such as peripheral diabetic neuropathy and, more recently, in ocular diseases. In this review, we outline the principles and applications of IVCM in the study of corneal nerves in various ocular and systemic diseases.

Arafat SN, Robert M-C, Abud T, Spurr-Michaud S, Amparo F, Dohlman CH, Dana R, Gipson IK. Elevated Neutrophil Elastase in Tears of Ocular Graft-Versus-Host Disease Patients. Am J Ophthalmol 2017;176:46-52.Abstract

PURPOSE: To investigate the levels of neutrophil elastase (NE), matrix metalloproteinases (MMPs), and myeloperoxidase (MPO) in tear washes of patients with ocular graft-vs-host disease (oGVHD). DESIGN: Case-control study. METHODS: Based on established criteria, oGVHD patients (n = 14; 28 eyes) and age-/sex-matched healthy controls (n = 14; 28 eyes) were enrolled. Tear washes were collected and analyzed for NE using a single-analyte enzyme-linked immunosorbent assay (ELISA). MMPs (1, 2, 3, 7, 8, 9, 12), MPO, and tissue inhibitor of matrix metalloproteinase (TIMP)-1 were analyzed using multianalyte bead-based ELISA assays. Total MMP activity was measured using a fluorimetric assay. Correlation studies were performed between NE, MMP-8, MMP-9, and MPO within study groups. RESULTS: NE, MMP-8, MMP-9, and MPO levels were elevated in oGVHD tears when compared with controls (P < .0001). NE was the most elevated analyte. MMP activity was higher and TIMP-1 levels were lower in oGVHD than in control (P < .0001). In oGVHD, NE significantly correlated with MMP-8 (r = 0.92), MMP-9 (r = 0.90), and MPO (r = 0.79) (P < .0001). MMP-8 correlated with MMP-9 (r = 0.96, P < .0001), and MPO (r = 0.60, P = .001). MMP-9 correlated with MPO (r = 0.55, P = .002). In controls, NE, MMP-9, and MPO significantly correlated with each other (P < .0001). CONCLUSIONS: The marked increase in NE in oGVHD tears that correlated strongly with elevated MMP-8, MMP-9, and MPO suggests a common neutrophilic source and provides evidence of neutrophil activity on the ocular surface of oGVHD patients.

Kobashi H, Kamiya K, Shimizu K. Randomized Comparison Between Rebamipide Ophthalmic Suspension and Diquafosol Ophthalmic Solution for Dry Eye After Penetrating Keratoplasty. J Ocul Pharmacol Ther 2017;33(1):13-18.Abstract

PURPOSE: To compare the ocular surfaces of patients treated with rebamipide (REB) ophthalmic suspension or diquafosol (DQS) ophthalmic solution for dry eye syndrome after penetrating keratoplasty (PK). METHODS: A total of 40 eyes of 40 patients who had dry eyes after undergoing PK were enrolled and randomly divided into an REB group and a DQS group. Both REB and DQS groups used each eye drop four times. The tear breakup time (TBUT), corneal fluorescein staining scores, and dry eye-related quality-of-life score (DEQS) were evaluated before treatment, 2 weeks after start of treatment and 4 weeks after start of treatment. RESULTS: We found a significant improvement in TBUT (P < 0.001, Dunnett's test) and fluorescein scores (P < 0.001) 4 weeks after treatment in the REB group. Similar results were obtained in the DQS group (P < 0.001 and P = 0.01, respectively). No significant improvements in DEQS were found 4 weeks after treatment in each group (P = 0.15 and P = 0.63, analysis of variance, respectively). No significant differences were seen in these variables and in the changes between the groups after treatment. CONCLUSIONS: REB and DQS may be effective for the management of dry eye syndrome after PK in terms of ocular surface findings. In our study, effects of REB appear to be equivalent to those of DQS in the patients.

Mikolajczak J, Zimmermann H, Kheirkhah A, Kadas EM, Oberwahrenbrock T, Muller R, Ren A, Kuchling J, Dietze H, Prüss H, Paul F, Hamrah P, Brandt AU. Patients with multiple sclerosis demonstrate reduced subbasal corneal nerve fibre density. Mult Scler 2017;23(14):1847-1853.Abstract
BACKGROUND: Many studies in multiple sclerosis (MS) have investigated the retina. Little, however, is known about the effect of MS on the cornea, which is innervated by the trigeminal nerve. It is the site of neural-immune interaction with local dendritic cells reacting in response to environmental stimuli. OBJECTIVE: This study aims to investigate the effect of MS on corneal nerve fibres and dendritic cells in the subbasal nerve plexus using in vivo confocal microscopy (IVCM). METHODS: We measured the corneal nerve fibre and dendritic cell density in 26 MS patients and matched healthy controls using a Heidelberg Retina Tomograph with cornea module. Disease severity was assessed with the Multiple Sclerosis Functional Composite, Expanded Disability Status Scale, visual acuity and retinal optical coherence tomography. RESULTS: We observed significant reduction in total corneal nerve fibre density in MS patients compared to controls. Dendritic cell density was similar in both groups. Reduced total nerve fibre density was associated with worse clinical severity but not with previous clinical trigeminal symptoms, retinal neuro-axonal damage, visual acuity or disease duration. CONCLUSION: Corneal nerve fibre density is a promising new imaging marker for the assessment of disease severity in MS and should be investigated further.
Hamrah P, Qazi Y, Shahatit B, Dastjerdi MH, Pavan-Langston D, Jacobs DS, Rosenthal P. Corneal Nerve and Epithelial Cell Alterations in Corneal Allodynia: An In Vivo Confocal Microscopy Case Series. Ocul Surf 2017;15(1):139-151.Abstract

PURPOSE: To investigate morphological changes of the corneal epithelium and subbasal nerves in patients with corneal allodynia using in vivo confocal microscopy (IVCM). DESIGN: Case-control study of patients with corneal allodynia and healthy controls. METHODS: Ten eyes of six patients were diagnosed with corneal allodynia at a single center and compared to fifteen healthy eyes. IVCM of the central cornea was performed on all subjects and controls. Images were retrospectively analyzed numbers of total corneal subbasal nerves, main trunks and branches, total nerve length and density, nerve branching, and tortuosity, superficial and basal epithelial cell densities, and superficial epithelial cell size. RESULTS: Corneal allodynia was seen in patients with dry eye disease, recurrent corneal erosion syndrome, exposure to ultraviolet radiation, and Accutane use. Compared to controls, patients with corneal allodynia had a significant decrease in the total numbers of subbasal nerves (P=.014), nerve branches (P=.006), total nerve length (P=.0029), total nerve density (P=.0029) and superficial and basal epithelial cell densities (P=.0004, P=.0036) with an increase in superficial epithelial cell size (P=.016). There were no statistically significant differences in the number of subbasal nerve main trunks (P=.09), nerve branching (P=.21), and nerve tortuosity (P=.05). CONCLUSIONS: Corneal IVCM enables near-histological visualization and quantification of the cellular and neural changes in corneal allodynia. Regardless of etiology, corneal allodynia is associated with decreased corneal epithelial cell densities, increased epithelial cell size, and decreased numbers and lengths of subbasal nerves despite an unremarkable slit-lamp examination. Therefore, IVCM may be useful in the management of patients with corneal allodynia.

Liu S, Veldman P. Evidence-Based Endothelial Rehabilitation. Semin Ophthalmol 2017;32(1):96-103.Abstract

Endothelial keratoplasty (EK) has replaced penetrating keratoplasty (PKP) as the preferred surgical therapy for corneal endothelial dysfunction. However, recent nationwide corneal graft registry data showed few advantages to EK relative to PKP with respect to graft survival and visual outcomes. This article compares the published outcomes and complications of EK to those of PKP. EK demonstrates superior spectacle corrected visual outcomes, fast recovery, less graft rejection, and higher patient satisfaction, particularly in studies performed by high-volume surgeons/centers. Endothelial cell loss in EK, while higher at early time points, was equivalent or superior at five-years' follow-up and graft survival was equivalent to or superior to PKP in these centers/studies. Continued standardization and simplification of EK procedures may allow surgeons who perform a lower volume of EK to achieve results that mirror those of high-volume centers/surgeons and close the potential gap in outcomes demonstrated in the registry data.

Palioura S, Colby K. Outcomes of Descemet Stripping Endothelial Keratoplasty Using Eye Bank-Prepared Preloaded Grafts. Cornea 2017;36(1):21-25.Abstract

PURPOSE: To evaluate the feasibility of Descemet stripping endothelial keratoplasty using grafts preloaded by an eye bank in a commercially available insertion device. METHODS: In this retrospective case series, a series of 35 eyes in 34 consecutive patients who underwent Descemet stripping endothelial keratoplasty for Fuchs endothelial dystrophy or previously failed full-thickness grafts at a single tertiary care center from March 2013 to March 2014 was included. The donor tissue had undergone pre-lamellar dissection, trephination, and loading into EndoGlide Ultrathin inserters at the Lions Eye Institute for Transplant and Research (Tampa, FL) and was shipped overnight in Optisol GS to the surgeon (K.C.). Surgery was performed within 24 hours from tissue preparation and loading by the eye bank. Donor and recipient characteristics, endothelial cell density (ECD), best-corrected visual acuity, and central corneal thickness were recorded. The main outcome measures were intraoperative and postoperative complications and ECD loss at 3, 6, and 12 months. RESULTS: One primary graft failure (2.8%), 2 rebubblings (5.7%), and 1 graft rejection (2.8%) occurred. Mean preoperative donor ECD was 2821 ± 199 cells/mm. Six months postoperatively, the mean endothelial cell loss was 25.3% ± 17.2% (n = 32), which remained stable at 1 year (31.5% ± 17.9%, n = 32). Mean best-corrected visual acuity improved from 20/100 preoperatively to 20/25 at a mean follow-up of 1 year (n = 32). Mean central corneal thickness was reduced from 711 ± 110 μm to 638 ± 66 μm at the last follow-up visit. CONCLUSIONS: Donor graft tissue preloaded by an eye bank can be used successfully for endothelial keratoplasty. Preloading reduces intraoperative tissue manipulation.

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