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Ma J, Chen M, Ai J, Young MJ, Ge J. Enhanced migration of engrafted retinal progenitor cells into the host retina via disruption of glial barriers. Mol Vis 2021;27:300-308.Abstract
Purpose: Migration and integration remain critical challenges for stem cell replacement therapy. Glial barriers play an important role in preventing cell migration and integration. The purpose of this study was to investigate the effect and mechanisms of chondroitinase ABC on the migration of murine retinal progenitor cells (mRPCs) transplanted into the subretinal space of B6 mice. Methods: mRPCs were harvested from the neural retinas of P1 enhanced green fluorescent protein (GFP) B6 mice. Two μl containing 2 × 105 expanded RPCs alone or combined with chondroitinase ABC in suspension were injected into the subretinal space of the recipient B6 mice. Immunohistochemistry was performed on the recipient B6 retinas to evaluate the glial barrier formation and migration of the mRPCs. Western blotting was also used to check the expression of the glial barriers. Results: Glial fibrillary acidic protein (GFAP) and vimentin could be seen around the transplanted mRPCs in the B6 mice. Formation of glial barriers prevented the migration of donor cells into the retinal layers. Chondroitinase ABC promoted the migration and survival rates of the engrafted retinal progenitor cells in the retinal layers of recipient B6 mice. Injection induced upregulation of GFAP, chondroitin, and CD44 expression. Chondroitinase ABC disrupted the glial barriers. The CD44 around the mRPCs was much lower in the chondroitinase group. However, the CD44 in the retinal layers was considerably higher in the chondroitinase group. With the employment of chondroitinase ABC, more cells migrated into the outer nuclear layer or inner nuclear layer. The chondroitin and CD44 expression decreased 3 weeks after transplantation in the chondroitinase ABC group. Conclusions: Chondroitinase ABC degraded glial barriers and enhanced the migration of transplanted mouse retinal progenitor cells. Chondroitinase ABC may also have induced activation of the CD44 signaling pathway to exert the effect.
Ferenchak K, Deitch I, Huckfeldt R. Antisense Oligonucleotide Therapy for Ophthalmic Conditions. Semin Ophthalmol 2021;36(5-6):452-457.Abstract
Antisense oligonucleotides (AON) are synthetic single-stranded fragments of nucleic acids that bind to a specific complementary messenger RNA (mRNA) sequence and change the final gene product. AON were initially approved for treating cytomegalovirus retinitis and have shown promise in treating Mendelian systemic disease. AON are currently being investigated as a treatment modality for many ophthalmic diseases, including inherited retinal disorders (IRD), inflammatory response and wound healing after glaucoma surgery, and macular degeneration. They provide a possible solution to gene therapy for IRD that are not candidates for adeno-associated virus (AAV) delivery. This chapter outlines the historical background of AON and reviews clinical applications and ongoing clinical trials.
Yin J. Advances in corneal graft rejection. Curr Opin Ophthalmol 2021;32(4):331-337.Abstract
PURPOSE OF REVIEW: Immune rejection after corneal transplantation is a major risk for graft failure. We aim to summarize recent advances in the understanding and management of graft rejection. RECENT FINDINGS: Immune rejection remains the leading cause of graft failure in penetrating keratoplasty (PKP). While ABO blood type and sex match between donor and recipient may reduce rejection, human leucocyte antigens class II matching in a randomized study did not reduce the risk of rejection in high-risk PKP. Compared with PKP, deep anterior lamellar keratoplasty, descemet stripping automated endothelial keratoplasty, and descemet membrane endothelial keratoplasty have lower immune rejection rates of 1.7-13%, 5-11.4%, and 1.7-2.8%, respectively, based on long-term (5 years and more) studies. Whether immune rejection is a major risk factor for graft failure in these lamellar keratoplasties is unclear. While there have not been major advances in the systemic management of graft rejection, topical nonsteroid agents such as tacrolimus and anti-vascular endothelial growth factor have shown promise in high-risk cases. SUMMARY: Immune rejection remains the leading cause of graft failure in PKP. Lamellar keratoplasties have significantly lower rejection rates compared with PKP. The significance of rejection in the failure of lamellar grafts warrants further investigation.
Chan CK, Mein CE, Glassman AR, Beaulieu WT, Calhoun CT, Jaffe GJ, Jampol LM, MacCumber MW, Maguire MG, Maturi RK, Salehi-Had H, Rofagha S, Sun JK, Martin DF, Martin DF. Pneumatic Vitreolysis with Perfluoropropane for Vitreomacular Traction with and without Macular Hole: DRCR Retina Network Protocols AG and AH. Ophthalmology 2021;128(11):1592-1603.Abstract
PURPOSE: To evaluate pneumatic vitreolysis (PVL) in eyes with vitreomacular traction (VMT) with and without full-thickness macular hole (FTMH). DESIGN: Two multicenter (28 sites) studies: a randomized clinical trial comparing PVL with observation (sham injection) for VMT without FTMH (Protocol AG) and a single-arm study assessing PVL for FTMH (Protocol AH). PARTICIPANTS: Participants were adults with central VMT (vitreomacular adhesion was ≤3000 μm). In Protocol AG, visual acuity (VA) was 20/32 to 20/400. In Protocol AH, eyes had a FTMH (≤250 μm at the narrowest point) and VA of 20/25 to 20/400. METHODS: Pneumatic vitreolysis using perfluoropropane (C3F8) gas. MAIN OUTCOME MEASURES: Central VMT release at 24 weeks (Protocol AG) and FTMH closure at 8 weeks (Protocol AH). RESULTS: From October 2018 through February 2020, 46 participants were enrolled in Protocol AG, and 35 were enrolled in Protocol AH. Higher than expected rates of retinal detachment and tear resulted in early termination of both protocols. Combining studies, 7 of 59 eyes (12% [95% CI, 6%-23%]; 2 eyes in Protocol AG, 5 eyes in Protocol AH) that received PVL developed rhegmatogenous retinal detachment (n = 6) or retinal tear (n = 1). At 24 weeks in Protocol AG, 18 of 23 eyes in the PVL group (78%) versus 2 of 22 eyes in the sham group (9%) achieved central VMT release without rescue vitrectomy (adjusted risk difference, 66% [95% CI, 44%-88%]; P< 0.001). The mean change in VA from baseline at 24 weeks was 6.7 letters in the PVL group and 6.1 letters in the sham group (adjusted difference, -0.8 [95% CI, -6.1 to 4.5]; P = 0.77). In Protocol AH, 10 of 35 eyes (29% [95% CI, 16%-45%]) achieved FTMH closure without rescue vitrectomy at 8 weeks. The mean change in VA from baseline at 8 weeks was -1.5 letters (95% CI, -10.3 to 7.3 letters). CONCLUSIONS: In most eyes with VMT, PVL induced hyaloid release. In eyes with FTMH, PVL resulted in hole closure in approximately one third of eyes. These studies were terminated early because of safety concerns related to retinal detachments and retinal tears.
Currant H, Hysi P, Fitzgerald TW, Gharahkhani P, Bonnemaijer PWM, Senabouth A, Hewitt AW, and Consortium UKBEV, and Consortium UKBEV, Atan D, Aung T, Charng J, Choquet H, Craig J, Khaw PT, Klaver CCW, Kubo M, Ong J-S, Pasquale LR, Reisman CA, Daniszewski M, Powell JE, Pébay A, Simcoe MJ, Thiadens AAHJ, van Duijn CM, Yazar S, Jorgenson E, Macgregor S, Hammond CJ, Mackey DA, Wiggs JL, Foster PJ, Patel PJ, Birney E, Khawaja AP. Genetic variation affects morphological retinal phenotypes extracted from UK Biobank optical coherence tomography images. PLoS Genet 2021;17(5):e1009497.Abstract
Optical Coherence Tomography (OCT) enables non-invasive imaging of the retina and is used to diagnose and manage ophthalmic diseases including glaucoma. We present the first large-scale genome-wide association study of inner retinal morphology using phenotypes derived from OCT images of 31,434 UK Biobank participants. We identify 46 loci associated with thickness of the retinal nerve fibre layer or ganglion cell inner plexiform layer. Only one of these loci has been associated with glaucoma, and despite its clear role as a biomarker for the disease, Mendelian randomisation does not support inner retinal thickness being on the same genetic causal pathway as glaucoma. We extracted overall retinal thickness at the fovea, representative of foveal hypoplasia, with which three of the 46 SNPs were associated. We additionally associate these three loci with visual acuity. In contrast to the Mendelian causes of severe foveal hypoplasia, our results suggest a spectrum of foveal hypoplasia, in part genetically determined, with consequences on visual function.
Rubinfeld RS, Gum GG, Talamo JH, Parsons EC. The Effect of Sodium Iodide on Stromal Loading, Distribution and Degradation of Riboflavin in a Rabbit Model of Transepithelial Corneal Crosslinking. Clin Ophthalmol 2021;15:1985-1994.Abstract
Purpose: To evaluate effects of sodium iodide (NaI) on riboflavin concentration in corneal stroma before and during ultraviolet A (UVA) light exposure using a novel transepithelial corneal collagen crosslinking (CXL) procedure (EpiSmart CXL system, CXL Ophthalmics, Encinitas CA). Methods: Riboflavin solutions with NaI (Ribostat, CXL Ophthalmics, Encinitas CA) and without NaI were used for CXL in rabbits using EpiSmart. A pilot study determined sufficient riboflavin loading time. Four rabbits were dosed and monitored. Riboflavin fluorescence intensity was assessed from masked slit-lamp photos. A 12 min loading time was selected. Sixteen additional rabbits received the two formulae in contralateral eyes for CXL. Riboflavin uptake was assessed at 0, 10, 15, 20, 25, and 30 min of UVA exposure using a scale for riboflavin fluorescence previously validated against stromal concentration. Post sacrifice, corneal stromal samples were analyzed for concentrations of riboflavin and riboflavin 5'-phosphate. Results: Eyes dosed with NaI riboflavin had higher riboflavin grades compared to eyes dosed with the NaI-free riboflavin formulation immediately after riboflavin loading and persisting throughout UVA exposure, with significantly higher (P < 0.01 to < 0.05) riboflavin grades from 15 through 25 min of UVA exposure. Riboflavin grades decreased more slowly in eyes dosed with NaI riboflavin through 25 minutes of UVA exposure. Minor conjunctival irritation was noted with or without NaI. Conclusion: The addition of NaI to riboflavin solution is associated with increased riboflavin concentration in corneal stroma throughout a clinically relevant time course of UVA exposure. This effect may be a combination of enhanced epithelial penetration and reduced riboflavin photodegradation and should enhance intrastromal crosslinking.
Sobrin L, Yu Y, Han S, Susarla G, Kempen JH, Hubbard RA, VanderBeek BL. Decreased risk of non-infectious anterior uveitis with statin therapy in a large healthcare claims database. Graefes Arch Clin Exp Ophthalmol 2021;259(9):2783-2793.Abstract
PURPOSE: The purpose of this study is to determine if statin therapy decreases the incidence of non-infectious uveitis (NIU) using a retrospective cohort study. METHODS: Patients enrolled in a national insurance plan who initiated statin (n = 711,734, statin cohort) or other lipid-lowering therapy (n = 148,044, non-statin cohort) were observed for NIU development. Incident NIU in the primary analysis was defined as a new diagnosis code for NIU followed by a second instance of a NIU code within 120 days. For the secondary outcome definition, a corticosteroid prescription or code for an ocular corticosteroid injection within 120 days of the NIU diagnosis code was used instead of the second NIU diagnosis code. Estimation of NIU incidence used multivariable Cox proportional hazards regression. The proportional hazards assumption was satisfied by creating two time periods of analysis, ≤ 150 and > 150 days. Subanalyses were performed by anatomic subtype. RESULTS: Overall, the primary outcome occurred 541 times over 690,465 person-years in the statin cohort and 103 times over 104,301 person-years in the non-statin cohort. No associations were seen in the ≤ 150-day analyses (p > 0.20 for all comparisons). However, after 150 days, the statin cohort was less likely to develop any uveitis [hazard ratio (HR) = 0.70, 95% confidence interval (CI): 0.51-0.97, P = 0.03] in the primary outcome analysis, but did not meet significance for the secondary outcome (HR = 0.85, 95% CI: 0.63-1.15, P = 0.30). Similarly, in the anatomic subtype analysis, after 150 days, the statin cohort was less likely to develop anterior uveitis (HR = 0.67, 95% CI: 0.47-0.97, P = 0.03) in the primary analysis, but the association did not reach significance for the secondary outcome (HR = 0.82, 95% CI: 0.56-1.20, P = 0.31). CONCLUSION: Our results suggest that statin therapy for > 150 days decreases the incidence of NIU.
Gupta PK, Venkateswaran N. The role of KPI-121 0.25% in the treatment of dry eye disease: penetrating the mucus barrier to treat periodic flares. Ther Adv Ophthalmol 2021;13:25158414211012797.Abstract
The tear film, which includes mucins that adhere to foreign particles, rapidly clears allergens and pathogens from the ocular surface, protecting the underlying tissues. However, the tear film's ability to efficiently remove foreign particles during blinking can also pose challenges for topical drug delivery, as traditional eye drops (solutions and suspensions) are cleared from the ocular surface before the drug can penetrate into the conjunctival and corneal epithelium. In the past 15 years, there has been an increase in the development of nanoparticles with specialized coatings that have reduced affinity to mucins and are small enough in size to pass through the mucus barrier. These mucus-penetrating particles (MPPs) have been shown to efficiently penetrate the mucus barrier and reach the ocular surface tissues. Dry eye disease (DED) is a common inflammatory ocular surface disorder that often presents with periodic flares (exacerbations). However, currently approved immunomodulatory treatments for DED are intended for long-term use. Thus, there is a need for effective short-term treatments that can address intermittent flares of DED. Loteprednol etabonate, an ocular corticosteroid, was engineered to break down rapidly after administration to the ocular surface tissues and thereby reduce risks associated with other topical steroids. KPI-121 is an ophthalmic suspension that uses the MPP technology to deliver loteprednol etabonate more efficiently to the ocular tissues, achieving in animal models a 3.6-fold greater penetration of loteprednol etabonate to the cornea than traditional loteprednol etabonate ophthalmic suspensions. In clinical trials, short-term treatment with KPI-121 0.25% significantly reduced signs and symptoms of DED compared with its vehicle (placebo). Recently approved KPI-121 0.25%, with its novel drug delivery design and ease of use, has the potential to effectively treat periodic flares of DED experienced by many patients.
Singh RB, Liu L, Yung A, Anchouche S, Mittal SK, Blanco T, Dohlman TH, Yin J, Dana R. Ocular redness - II: Progress in development of therapeutics for the management of conjunctival hyperemia. Ocul Surf 2021;21:66-77.Abstract
Conjunctival hyperemia is one of the most common causes for visits to primary care physicians, optometrists, ophthalmologists, and emergency rooms. Despite its high incidence, the treatment options for patients with conjunctival hyperemia are restricted to over-the-counter drugs that provide symptomatic relief due to short duration of action, tachyphylaxis and rebound redness. As our understanding of the immunopathological pathways causing conjunctival hyperemia expands, newer therapeutic targets are being discovered. These insights have also contributed to the development of animal models for mimicking the pathogenic changes in microvasculature causing hyperemia. Furthermore, this progress has catalyzed the development of novel therapeutics that provide efficacious, long-term relief from conjunctival hyperemia with minimal adverse effects.
Keffeler EC, Iyer VS, Parthasarathy S, Ramsey MM, Gorman MJ, Barke TL, Varahan S, Olson S, Gilmore MS, Abdullahi ZH, Hancock EN, Hancock LE. Influence of the Alternative Sigma Factor RpoN on Global Gene Expression and Carbon Catabolism in Enterococcus faecalis V583. mBio 2021;12(3)Abstract
The alternative sigma factor σ54 has been shown to regulate the expression of a wide array of virulence-associated genes, as well as central metabolism, in bacterial pathogens. In Gram-positive organisms, the σ54 is commonly associated with carbon metabolism. In this study, we show that the Enterococcus faecalis alternative sigma factor σ54 (RpoN) and its cognate enhancer binding protein MptR are essential for mannose utilization and are primary contributors to glucose uptake through the Mpt phosphotransferase system. To gain further insight into how RpoN contributes to global transcriptional changes, we performed microarray transcriptional analysis of strain V583 and an isogenic rpoN mutant grown in a chemically defined medium with glucose as the sole carbon source. Transcripts of 340 genes were differentially affected in the rpoN mutant; the predicted functions of these genes mainly related to nutrient acquisition. These differentially expressed genes included those with predicted catabolite-responsive element (cre) sites, consistent with loss of repression by the major carbon catabolite repressor CcpA. To determine if the inability to efficiently metabolize glucose/mannose affected infection outcome, we utilized two distinct infection models. We found that the rpoN mutant is significantly attenuated in both rabbit endocarditis and murine catheter-associated urinary tract infection (CAUTI). Here, we examined a ccpA mutant in the CAUTI model and showed that the absence of carbon catabolite control also significantly attenuates bacterial tissue burden in this model. Our data highlight the contribution of central carbon metabolism to growth of E. faecalis at various sites of infection.IMPORTANCE Hospital-acquired infections account for 2 billion dollars annually in increased health care expenses and cause more than 100,000 deaths in the United States alone. Enterococci are the second leading cause of hospital-acquired infections. They form biofilms at surgical sites and are often associated with infections of the urinary tract following catheterization. Nutrient uptake and growth are key factors that influence their ability to cause disease. Our research identified a large set of genes that illuminate nutrient uptake pathways in enterococci. Perturbation of the metabolic circuit reduces virulence in a rabbit endocarditis model, as well as in catheter-associated urinary tract infection in mice. Targeting metabolic pathways that are important in infection may lead to new treatments against multidrug-resistant enterococcal infections.
Williams IM, Pineda R, Neerukonda VK, Stagner AM. Mucopolysaccharidosis Type I-Associated Corneal Disease: A Clinicopathologic Study. Am J Ophthalmol 2021;231:39-47.Abstract
PURPOSE: To report the anterior segment clinical features and histopathologic and histochemical characteristics of explanted corneas from the largest reported cohort of patients with Hurler syndrome and other variants of mucopolysaccharidosis (MPS) I undergoing corneal transplantation. DESIGN: Retrospective observational case series. METHODS: This institutional study reviewed 15 corneas from 9 patients with MPS I spectrum disease who underwent corneal transplant to treat corneal clouding between May 2011 and October 2020. We reviewed the clinical data, hematoxylin-eosin-stained sections, and histochemical stains, including those for mucopolysaccharides (Alcian blue and/or colloidal iron). The main outcome measures were pathology observed under light microscopy and postsurgical clinical outcomes. RESULTS: Nine patients underwent 15 corneal transplants for corneal clouding (14/15 procedures were deep anterior lamellar keratoplasty). All corneas had mucopolysaccharide deposition visible on hematoxylin-eosin-stained sections, which was highlighted in blue with histochemical stains. All corneas also showed alterations in Bowman's layer and the majority also showed epithelial abnormalities. CONCLUSION: MPS I shows significant corneal clouding that is successfully treated with deep anterior lamellar keratoplasty. The excised corneas show characteristic epithelial changes, disruption or breaks in Bowman's membrane, and amphophilic collections of stromal granular mucopolysaccharides which are visible on hematoxylin-eosin-stained sections and highlighted by special histochemical stains (Alcian blue and collodial iron). These changes, although subtle, should alert the pathologist to the possibility of an underlying lysosomal storage disorder.
Ma KK, Ong Tone S, Chodosh J, Saeed HN. Ochrobactrum anthropi Keratitis in a Boston Type 1 Keratoprosthesis Recipient. Cornea 2021;40(5):662-663.Abstract
PURPOSE: To report a case of Ochrobactrum anthropi keratitis in an eye with a Boston type 1 keratoprosthesis. METHODS: This is a case report and review of the literature. RESULTS: A 78-year-old man with a history of implantation of a Boston type 1 keratoprosthesis in the left eye presented for a routine follow-up with no acute complaints. In the left eye, visual acuity was 20/60 and slit-lamp examination revealed a 1.5-mm inferotemporal corneal infiltrate adjacent to the optic stem. Corneal cultures grew abundant O. anthropi. After 7 weeks of topical antimicrobial therapy and placement of a temporary tarsorrhaphy, the keratitis resolved. CONCLUSIONS: Ochrobactrum anthropi is an organism associated with indwelling medical devices and can be pathogenic in eyes with implanted keratoprostheses.
Venkateswaran N, Sripawadkul W, Karp CL. The role of imaging technologies for ocular surface tumors. Curr Opin Ophthalmol 2021;32(4):369-378.Abstract
PURPOSE OF REVIEW: This review will discuss the utility of high-resolution anterior segment optical coherence tomography (HR-OCT), in-vivo confocal microscopy (IVCM) and ultrasound biomicroscopy (UBM) in characterizing and diagnosing various ocular surface tumors, namely ocular surface squamous neoplasia (OSSN), conjunctival lymphoma and conjunctival melanoma. The strengths and limitations of each imaging modality will be discussed along with the characteristics findings of each lesion on each imaging platform. RECENT FINDINGS: HR-OCT can consistently be utilized in the clinic setting to distinguish between epithelial ocular surface tumors such as OSSN as compared with subepithelial tumors such as conjunctival lymphoma and conjunctival melanoma given their distinctive findings. IVCM can be used as an adjunct to HR-OCT to obtain cellular and surface characteristics, whereas UBM can be used to assess tumor depth and thickness for larger and highly pigmented lesions as well as to detect intraocular invasion. SUMMARY: HR-OCT, IVCM and UBM are all helpful imaging modalities to diagnose and characterize various ocular surface tumors and can serve as valuable adjuncts to monitor treatment response and assess for recurrence ocular surface tumors.

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