The Eye Sees Eye to Eye With the Immune System: The 2019 Proctor Lecture

Exploitation of enhanced prime editing for blocking aberrant angiogenesis

INTRODUCTION

Aberrant angiogenesis plays an important part in the development of a variety of human diseases including proliferative diabetic retinopathy, with which there are still numerous patients remaining a therapeutically challenging condition. Prime editing (PE) is a versatile gene editing approach, which offers a novel opportunity to genetically correct challenging disorders.

OBJECTIVES

The goal of this study was to create a dominant-negative (DN) vascular endothelial growth factor receptor (VEGFR) 2 by editing genomic DNA with an advanced PE system to block aberrant retinal angiogenesis in a mouse model of oxygen-induced retinopathy.

METHODS

An advanced PE system (referred to as PE6x) was established within two lentiviral vectors, with one carrying an enhanced PE guide RNA and a canonical Cas9 nickase fused with an optimized reversal transcriptase, and the other conveying a nicking guide RNA and a DN-MLH1 to improve PE efficiency. Dual non-integrating lentiviruses (NILVs) produced with the two lentiviral PE6x vectors were then employed to create a mutation of VEGFR2 T17967A by editing the Mus musculus VEGFR2 locus in vitro and in vivo, leading to generation of a premature stop codon (TAG, K796stop) to produce DN-VEGFR2, to interfere with the wild type VEGFR2 which is essential for angiogenesis.

RESULTS

NILVs targeting VEGFR2 delivered into cultured murine vascular endothelial cells led to 51.06 % VEGFR2 T17967A in the genome analyzed by next generation sequencing and the production of DN-VEGFR2, which was found to hamper VEGF-induced VEGFR2 phosphorylation, as demonstrated by Western blot analysis. Intravitreally injection of the dual NILVs into postnatal day 12 mice in a model of oxygen-induced retinopathy, led to production of retinal DN-VEGFR2 in postnatal day 17 mice which blocked retinal VEGFR2 expression and activation as well as abnormal retinal angiogenesis without interfering with retinal structure and function, as assessed by electroretinography, optical coherence tomography, fundus fluorescein angiography and histology.

CONCLUSION

DN-VEGFR2 resulted from editing genomic VEGFR2 using the PE6x system can be harnessed to treat intraocular pathological angiogenesis.

The anterior chamber of the eye technology and its anatomical, optical, and immunological bases

The anterior chamber of the eye (ACE) is distinct in its anatomy, optics, and immunology. This guarantees that the eye perceives visual information in the context of physiology even when encountering adverse incidents like inflammation. In addition, this endows the ACE with the special nursery bed iris enriched in vasculatures and nerves. The ACE constitutes a confined space enclosing an oxygen/nutrient-rich, immune-privileged, and less stressful milieu as well as an optically transparent medium. Therefore, aside from visual perception, the ACE unexpectedly serves as an excellent transplantation site for different body parts and a unique platform for noninvasive, longitudinal, and intravital microimaging of different grafts. On the basis of these merits, the ACE technology has evolved from the prototypical through the conventional to the advanced version. Studies using this technology as a versatile biomedical research platform have led to a diverse range of basic knowledge and in-depth understanding of a variety of cells, tissues, and organs as well as artificial biomaterials, pharmaceuticals, and abiotic substances. Remarkably, the technology turns in vivo dynamic imaging of the morphological characteristics, organotypic features, developmental fates, and specific functions of intracameral grafts into reality under physiological and pathological conditions. Here we review the anatomical, optical, and immunological bases as well as technical details of the ACE technology. Moreover, we discuss major achievements obtained and potential prospective avenues for this technology.

Mannose-coupled AAV2: A second-generation AAV vector for increased retinal gene therapy efficiency

Inherited retinal diseases are a leading and untreatable cause of blindness and are therefore candidate diseases for gene therapy. Recombinant vectors derived from adeno-associated virus (rAAV) are currently the most promising vehicles for in vivo therapeutic gene delivery to the retina. However, there is a need for novel AAV-based vectors with greater efficacy for ophthalmic applications, as underscored by recent reports of dose-related inflammatory responses in clinical trials of rAAV-based ocular gene therapies. Improved therapeutic efficacy of vectors would allow for decreases in the dose delivered, with consequent reductions in inflammatory reactions. Here, we describe the development of new rAAV vectors using bioconjugation chemistry to modify the rAAV capsid, thereby improving the therapeutic index. Covalent coupling of a mannose ligand, via the formation of a thiourea bond, to the amino groups of the rAAV capsid significantly increases vector transduction efficiency of both rat and nonhuman primate retinas. These optimized rAAV vectors have important implications for the treatment of a wide range of retinal diseases.

Reactions to serum eye drops-New Zealand experience and review of the literature

BACKGROUND

Serum eye drops (SED) are used to treat ocular surface disease. Reactions to SED are poorly documented.

METHODS

We present our experience of self-reported reactions in New Zealand to SED (25%; autologous, allogeneic, or both) between 2003 and 2023, and a focused review of the literature.

RESULTS

In total, 1067 patients received SED treatment (562 autologous, 318 allogeneic, and 187 both). Three (0.5% of those treated with allogeneic SED) reported reactions. All appeared to be allergic. All were associated with allogeneic SED. We have information on two patients: one had an eye reaction; in the other, the gastrointestinal tract was involved. The literature contains few reports of reactions to SED. They have involved both autologous and allogeneic SED, and various SED concentrations. None appears to have been severe. Notably, no eye or systemic infections have been reported.

CONCLUSIONS

Information on the types and frequencies of reactions to SED is poor. This may be due to: serum being less likely to cause reactions; eyes being resistant to reactions; reactions being rare, and insufficient use of SED having occurred; under-reporting related to SED use at home and reactions being mild. More robust monitoring for reactions to SED is needed.

Signatures of adaptation in myopia-related genes on the sunlight exposure hypothesis

BACKGROUND

Myopia is a common eye disorder that results from gene-environment interactions. The prevalence of myopia varies across populations, and exposure to bright sunlight may prevent its development. We hypothesize that local adaptation to light environments during human migration played a role in shaping the genetic basis of myopia, and we aim to investigate how the environment influences the genetic basis of myopia.

METHOD

We utilized the whole-genome variant data of the 1000 Genomes Project for analysis. We searched myopia-associated loci that were under selection in Europeans using population branch statistics and the number of segregating sites by length statistics. The outliers of these statistics were enriched in the Kyoto Encyclopedia of Genes and Genomes pathways and the gene ontology biological process terms in searching for pathways that were under selection. We applied Bayesian inference to estimate the correlation between environmental factors and allele frequencies of the selected loci and performed causal inference of myopia using two-sample Mendelian randomization analysis.

RESULTS

We detected signatures of adaptation in vision and light perception pathways, supporting our hypothesis of sunlight adaptation. We discovered a strong correlation between latitude and allele frequencies in genes that are under significant selection, and we found pleiotropic effects of pigmentation or circadian rhythm genes on myopia, indicating that sunlight exposure influences the genetic diversity of myopia.

CONCLUSIONS

Myopia genes involved in light perception showed signs of selection. Local adaptation during human migration shaped the genetic basis of myopia and may have influenced its global prevalence distribution.

Looking beyond Self-Protection: The Eyes Instruct Systemic Immune Tolerance Early in Life

The eyes provide themselves with immune tolerance. Frequent skin inflammatory diseases in young blind people suggest, nonetheless, that the eyes instruct a systemic immune tolerance that benefits the whole body. We tested this premise by using delayed skin contact hypersensitivity (DSCH) as a tool to compare the inflammatory response developed by sighted (S) and birth-enucleated (BE) mice against oxazolone or dinitrofluorobenzene at the ages of 10, 30 and 60 days of life. Adult mice enucleated (AE) at 60 days of age were also assessed when they reached 120 days of life. BE mice displayed exacerbated DSCH at 60 but not at 10 or 30 days of age. AE mice, in contrast, show no exacerbated DSCH. Skin inflammation in 60-day-old BE mice was hapten exclusive and supported by distinct CD8+ lymphocytes. The number of intraepidermal T lymphocytes and migrating Langerhans cells was, however, similar between S and BE mice by the age of 60 days. Our observations support the idea that the eyes instruct systemic immune tolerance that benefits organs outside the eyes from an early age. The higher prevalence of inflammatory skin disorders reported in young people might then reflect reduced immune tolerance associated with the impaired functional morphology of the eyes.

Autoimmune Inflammatory Eye Disease: Demystifying Clinical Presentations for the Internist

PURPOSE OF REVIEW

Provide a framework for recognizing key symptoms and clinical findings in patients with autoimmune inflammatory eye disease.

RECENT FINDINGS

The most common manifestations of autoimmune inflammatory eye disease are episcleritis, scleritis, uveitis (anterior, intermediate, posterior, and panuveitis), and keratoconjunctivitis sicca. Etiologies can be idiopathic or in association with a systemic autoimmune condition. Referral of patients who may have scleritis is critical for patients presenting with red eyes. Referral of patients who may have uveitis is critical for patients presenting often with floaters and vision complaints. Attention should also be directed to aspects of the history that might suggest a diagnosis of a systemic autoimmune condition, immunosuppression, drug-induced uveitis, or the possibility of a masquerade condition. Infectious etiologies should be ruled out in all cases. Patients with autoimmune inflammatory eye disease may present with ocular or systemic symptoms alone, or in combination. Collaboration with ophthalmologists and other relevant specialists is vital to optimal long-term medical care.

Enhanced immune responses to vaccine antigens in the corneal stroma

To examine the widely accepted dogma that the eye is an immune-privileged organ that can suppress antigen immunogenicity, we explored systemic immune responses to a model vaccine antigen (tetanus toxoid) delivered to six compartments of the rodent eye (ocular surface, corneal stroma, anterior chamber, subconjunctival space, suprachoroidal space, vitreous body). We discovered that antigens delivered to corneal stroma induced enhanced, rather than suppressed, antigen-specific immune responses, which were 18- to 30-fold greater than conventional intramuscular injection and comparable to intramuscular vaccination with alum adjuvant. Systemic immune responses to antigen delivered to the other ocular compartments were much weaker. The enhanced systemic immune responses after intrastromal injection were related to a sequence of events involving the formation of an antigen "depot" in the avascular stroma, infiltration of antigen-presenting cells, up-regulation of MHC class II and costimulatory molecules CD80/CD86, and induction of lymphangiogenesis in the corneal stroma facilitating sustained presentation of antigen to the lymphatic system. These enhanced immune responses in corneal stroma suggest new approaches to medical interventions for ocular immune diseases and vaccination methods.

Aqueous Humor Cytokines in Non-Proliferative Diabetic Retinopathy

Background and Objectives: Cytokines are cell-signaling proteins whose identification may serve as inflammatory markers or early indicators for progressive disease. The aim of our study was to quantify several cytokines in aqueous humor (AH) and their correlations with biochemical parameters in diabetic eyes with non-proliferative diabetic retinopathy (NPDR). Materials and Methods: A total of 62 eyes from 62 patients were included in the study: 37 eyes from nondiabetic patients (group 1), 13 diabetic eyes with no retinopathy changes (group 2) and 12 diabetic eyes with early and moderate NPDR (group 3). AH samples were collected during uneventful cataract surgery. The cytokines IL-1β, IL-6, IL-8, IL-10, IL-12, IP-10, MCP-1, TNF-α and VEGF were quantified using multiplex bead-based immunoassay. Due to unreliable results, IL-1β, TNF-α, IL-10 and IL-12 were excluded. Concentrations were compared between groups. Biochemical parameters (fasting blood sugar, glycated hemoglobin, C-reactive protein) and the duration of diabetes were recorded. Results: VEGF levels were significantly different between groups (p = 0.001), while levels of IL-6, IL-8, IP-10 and MCP-1 were comparable across all groups (p > 0.05). IL-6 concentration correlated with VEGF in group 1 (rho = 0.651, p = 0.003) and group 3 (rho = 0.857, p = 0.007); no correlation could be proved between IL-6, IL-8, IP-10, MCP-1 or VEGF and biochemical parameters. Duration of diabetes was not correlated with the cytokine levels in groups 2 and 3. The receiver operating characteristic (ROC) curve revealed that VEGF concentrations could discriminate early and moderate NPDR from diabetes, with an area under the curve (AUC) of 0.897 (p = 0.001, 95% CI = 0.74−1.0). Conclusions: Diabetes mellitus induces significant intraocular changes in the VEGF expression in diabetic patients vs. normal subjects, even before proliferative complications appear. VEGF was increasingly expressed once the diabetes progressed from no retinopathy to early or moderate retinopathy.

Increased Complement-Associated Inflammation in Cytomegalovirus-Positive Hypertensive Anterior Uveitis Patients Based on the Aqueous Humor Proteomics Analysis

Herpetic anterior uveitis-associated ocular inflammation is commonly manifested with ocular hypertension and glaucoma. Relative to other viruses, cytomegalovirus (CMV) positive hypertensive anterior uveitis is associated with high recurrences of uveitis, as well as with uncontrolled intraocular pressure (IOP) and a subsequent higher requirement for future glaucoma surgery. To gain novel insights into the pathogenesis of ocular hypertension in these patients, we investigated the proteome changes of the aqueous humor (AH) derived from the CMV hypertensive anterior uveitis (CMV-HAU; n = 10) patients and non-glaucoma (cataract; n = 10) patients using liquid chromatography with tandem mass spectrometry. Among a total of 562 proteins identified, fifty and fifteen proteins were significantly elevated and decreased, respectively, in the AH of CMV-HAU patients compared to the control subjects by ≥2 fold. Gene ontology (GO) enrichment and network analyses of elevated proteins revealed that the enrichment of protein was involved in the complement activation, the humoral immune response mediated by the circulating immunoglobulins, proteolysis, and platelet degranulation. In the AH of CMV-HAU, GDF (growth/differentiation factor)-15, the inflammatory marker belonging to the TGF-β superfamily proteins, was significantly increased, while vasorin, an anti-TGF-β protein, levels were decreased. The trabecular meshwork cells infected with CMV exhibited a significantly increased expression of inflammatory markers. Collectively, these data indicate increased complement factor associated inflammation and humoral immunity in CMV-HAU associated ocular hypertension.

An Experimental Model of Neuro-Immune Interactions in the Eye: Corneal Sensory Nerves and Resident Dendritic Cells

The cornea is an avascular connective tissue that is crucial, not only as the primary barrier of the eye but also as a proper transparent refractive structure. Corneal transparency is necessary for vision and is the result of several factors, including its highly organized structure, the physiology of its few cellular components, the lack of myelinated nerves (although it is extremely innervated), the tightly controlled hydration state, and the absence of blood and lymphatic vessels in healthy conditions, among others. The avascular, immune-privileged tissue of the cornea is an ideal model to study the interactions between its well-characterized and dense sensory nerves (easily accessible for both focal electrophysiological recording and morphological studies) and the low number of resident immune cell types, distinguished from those cells migrating from blood vessels. This paper presents an overview of the corneal structure and innervation, the resident dendritic cell (DC) subpopulations present in the cornea, their distribution in relation to corneal nerves, and their role in ocular inflammatory diseases. A mouse model in which sensory axons are constitutively labeled with tdTomato and DCs with green fluorescent protein (GFP) allows further analysis of the neuro-immune crosstalk under inflammatory and steady-state conditions of the eye.

Tear Neuromediator and Corneal Denervation Following SMILE

PURPOSE

To investigate the changes in tear neuromediators and corneal subbasal nerve plexus following small incision lenticule extraction (SMILE) and to study its association with different refractive power of corrections.

METHODS

Thirty patients were included for tear neuromediator analysis (40 eyes) and corneal nerve analysis using in vivo confocal microscopy scans (20 eyes). Tear samples were collected preoperatively and 1 week and 1, 3, 6, and 12 months postoperatively and analyzed for the substance P, calcitonin gene-related peptide (CGRP), and nerve growth factor (NGF) concentrations using the enzyme-linked immunosor-bent assay (ELISA).

RESULTS

Corneal nerve fiber density (CNFD), corneal nerve fiber length (CNFL), and corneal nerve branch density (CNBD) decreased significantly postoperatively, then gradually increased from 3 months onward, but did not recover to the baseline levels at 12 months. Tear substance P and CGRP levels remained stable over 12 months. Tear NGF levels demonstrated a small peak at 1 week before decreasing significantly compared to preoperative levels at 6 months (P = .03) and 12 months (P = .007). The 1-month reduction in CNFL, tear substance P, and CGRP concentrations were significantly correlated with the corrected spherical equivalent (SE) (r = 0.71 for CNFL; r = -0.33 to -0.52 at different time points for substance P and CGRP, respectively, all P < .05). Compared to the low to moderate myopia group, the high myopia group (corrected SE greater than -6.00 diopters) had a significantly greater decrease in CNFD, significantly higher tear substance P concentrations at 1 week, 1 month, and 6 months, and significantly higher tear CGRP concentrations at 1 and 6 months.

CONCLUSIONS

These results provide new insight into the neurobiological responses and their potential implications in corneal nerve damage and recovery after SMILE. High myopia treatment was associated with greater corneal denervation and neuroinflammation. [J Refract Surg. 2021;37(8):516-523.].

"Corneal Nerves, CD11c+ Dendritic Cells and Their Impact on Ocular Immune Privilege"

The eye and the brain have limited capacities for regeneration and as such, immune-mediated inflammation can produce devastating consequences in the form of neurodegenerative diseases of the central nervous system or blindness as a result of ocular inflammatory diseases such as uveitis. Accordingly, both the eye and the brain are designed to limit immune responses and inflammation – a condition known as “immune privilege”. Immune privilege is sustained by physiological, anatomical, and regulatory processes that conspire to restrict both adaptive and innate immune responses.

Bilateral Corneal Perforation in a Patient Under Anti-PD1 Therapy

ABSTRACT

Immune checkpoint inhibition has improved the clinical outcomes for numerous patients with cancer. However, the downside is a whole new spectrum of immune-related adverse events. We report a 68-year-old man with a history of nonsmall cell lung cancer presenting with a spontaneous corneal perforation in the right eye after 22 cycles of pembrolizumab. In addition, a chronic central nonhealing epithelial defect developed after performing a penetrating keratoplasty. Treatment with autologous serum drops resulted in complete healing of the corneal ulcer, where other conventional therapies had no effect. One month after reinitiating pembrolizumab therapy, our patient presented again with a corneal perforation in the fellow eye. This case describes relapsing sterile ulcerations associated with pembrolizumab use and presents an unexpected cure.

Distinguishing Features of High- and Low-Dose Vaccine against Ocular HSV-1 Infection Correlates with Recognition of Specific HSV-1-Encoded Proteins

The protective efficacy of a live-attenuated HSV type 1 (HSV-1) vaccine, HSV-1 0∆ nuclear location signal (NLS), was evaluated in mice prophylactically in response to ocular HSV-1 challenge. Mice vaccinated with the HSV-1 0∆NLS were found to be more resistant to subsequent ocular virus challenge in terms of viral shedding, spread, the inflammatory response, and ocular pathology in a dose-dependent fashion. Specifically, a strong neutralizing Ab profile associated with low virus titers recovered from the cornea and trigeminal ganglia was observed in vaccinated mice in a dose-dependent fashion with doses ranging from 1 × 10³ to 1 × 10⁵ PFU HSV-1 0∆NLS. This correlation also existed in terms of viral latency in the trigeminal ganglia, corneal neovascularization, and leukocyte infiltration and expression of inflammatory cytokines and chemokines in infected tissue with the higher doses (1 × 10⁴-1 × 10⁵ PFU) of the HSV-1 0∆NLS-vaccinated mice, displaying reduced viral latency, ocular pathology, or inflammation in comparison with the lowest dose (1 × 10³ PFU) or vehicle vaccine employed. Fifteen HSV-1-encoded proteins were uniquely recognized by antisera from high-dose (1 × 10⁵ PFU)-vaccinated mice in comparison with low-dose (1 × 10³ PFU)- or vehicle-vaccinated animals. Passive immunization using high-dose-vaccinated, but not low-dose-vaccinated, mouse sera showed significant efficacy against ocular pathology in HSV-1-challenged animals. In summary, we have identified the minimal protective dose of HSV-1 0∆NLS vaccine in mice to prevent HSV-mediated disease and identified candidate proteins that may be useful in the development of a noninfectious prophylactic vaccine against the insidious HSV-1 pathogen.